Gas treatment method and apparatus

Abstract

Aspects of the present invention relate to a gas treatment apparatus (1) for treating a process gas. The gas treatment apparatus (1) includes a primary treatment unit (2) and a secondary treatment unit (3), and the primary and secondary treatment units (2, 3) are configured to treat the process gas. The primary treatment unit (2) includes a primary process gas inlet (10) for receiving the process gas, first and second primary absorption towers (12, 13) for treating the process gas, and at least one primary process gas outlet for discharging the treated process gas from the first and second primary absorption towers (12, 13). The secondary treatment unit (3) includes a secondary process gas inlet (30) for receiving the process gas, at least one secondary absorption tower (32, 33) for treating the process gas, and at least one secondary process gas outlet (31) for discharging the treated process gas from the at least one secondary absorption tower (32, 33) to the primary treatment unit (2). The primary treatment unit (2) can be selectively set to a first operating mode and a second operating mode. When operating in the first operating mode, the primary process gas inlet (10) is connected to the first primary absorption tower (12), and the process gas is supplied to the first primary absorption tower (12) for treatment. The second primary absorption tower (13) is connected to at least one secondary process gas outlet (31), and receives the treated process gas from the secondary treatment unit (3) to regenerate the second primary absorption tower (13). When operating in the second operating mode, the primary process gas inlet (10) is connected to the second primary absorption tower (13), and the process gas is supplied to the second primary absorption tower (13) for treatment. The first primary absorption tower (12) is connected to at least one secondary process gas outlet (31), and receives the treated process gas from the secondary treatment unit (3) to regenerate the first primary absorption tower (12). Aspects of the present invention also relate to a method for controlling a gas treatment apparatus (1) for treating a process gas, and a liquid air energy storage plant.

Description

Technical Field

[0001] The present disclosure relates to a gas treatment method and a gas treatment apparatus. Aspects of the present invention relate to a gas treatment apparatus, a method for treating a process gas, a control unit, and a liquid air energy storage plant.

Background Art

[0002] An air purification unit (APU) is used to extract contaminants and undesirable compounds (hereinafter referred to as "contaminants") from an air stream and produce a "purified" air stream for processing. These typically operate using an adsorption process that adsorbs contaminants such as gases, water molecules, hydrocarbon particles, and other undesirable species onto the surface of an adsorbent. The adsorbent is carefully selected to preferentially adsorb the contaminants that the process designer desires to remove. There are two types of adsorption: physical adsorption and chemical adsorption.

[0003] APUs are well-known in the art of air liquefaction. These are used to produce a stream of clean and dry air to be liquefied, and in particular to prevent the process from being contaminated by the freezing of contaminants and to ensure a pure liquefied air product. Typically, the APU of an air liquefaction plant is configured to remove carbon dioxide, moisture, and hydrocarbons. The APU usually consists of a vessel containing a particle bed of adsorbent through which the process stream flows. Since the adsorption capacity of the adsorbent is finite, the APU operates in two main stages: adsorption and regeneration (also called desorption). Adsorption is an exothermic process that releases heat. Heat needs to be applied for desorption. Two of the main process parameters that affect adsorption are pressure and temperature, and by manipulating these, the equilibrium between the fluid and the adsorbent can be changed. In a physical adsorption process, adsorption increases with increasing pressure and decreases with increasing temperature. In a chemisorption process, the relationship with temperature is often more complex. For the sake of simplicity, the following description focuses on physical adsorption, but the principles of the present invention are equally applicable to chemisorption processes. Similarly, the following description focuses on the use of an APU for air liquefaction, but those skilled in the art will recognize that the principles of the present invention are applicable to any similar application.

[0004] During the adsorption process cycle, the pressure and temperature are controlled such that the adsorbent adsorbs during the adsorption stage and desorbs during the regeneration stage. In the pressure swing adsorption process, which is well known in the art, the pressure is controlled to be high during the adsorption stage and low during the regeneration stage. In the temperature swing adsorption process, which is well known in the art, the temperature is controlled to be low during adsorption and high during regeneration. In the combined cycle, during the adsorption stage, since the pressure of the process air flow is high and the temperature is low, contaminants are adsorbed onto the surface of the adsorbent. During the regeneration stage, a regeneration gas flow (which may be air or the like) at low pressure and high temperature flows through the bed. As a result, the equilibrium between the gas flow and the adsorbent changes, and the contaminants are desorbed from the adsorbent into the gas flow. The regeneration gas flow is typically then exhausted to the atmosphere to remove the contaminants from the system. The regeneration stage is usually followed by a cooling stage, where the adsorption bed is cooled to a lower temperature using a lower temperature gas flow before restarting the adsorption stage. The lower the temperature of the bed, the higher the adsorption efficiency. Since both the adsorption stage and the regeneration stage are required, the APU of the air separation plant is mainly composed of two containers so that purified air can flow continuously through the process. One container adsorbs while the other is regenerated and subsequently cooled. Once the effective capacity of the adsorption container is reached (saturation), the regeneration container becomes the adsorption container, and a valve system is used to switch the flow path so that the "full" container starts regeneration. During the regeneration stage, it is necessary to supply a regeneration gas. If the supply of the regeneration gas is insufficient or limited, it may be necessary to interrupt the process until the regeneration stage is completed. Summary of the Invention Problems to be Solved by the Invention

[0005] An object of the present invention is to address one or more of the drawbacks associated with the prior art. Means for Solving the Problems

[0006] As described in the appended claims, aspects and embodiments of the present invention provide a gas treatment device, a method for treating process gas, a control unit, and a liquid air energy storage plant.

[0007] According to one aspect of the present invention, there is provided a gas treatment device for treating process gas, the gas treatment device comprising a primary treatment unit and a secondary treatment unit, the primary treatment unit and the secondary treatment unit being configured to treat the process gas. The primary treatment unit includes a primary process gas inlet for receiving the process gas, a first primary absorption tower and a second primary absorption tower for treating the process gas, and at least one primary process gas outlet for discharging the process gas treated from the first primary absorption tower and the second primary absorption tower. The secondary treatment unit includes a secondary process gas inlet for receiving the process gas, at least one secondary absorption tower for treating the process gas, and at least one secondary process gas outlet for discharging the treated process gas from at least one secondary absorption tower to the primary treatment unit.

[0008] The process gas supplied to the primary treatment unit is treated by one of the first primary absorption tower and the second primary absorption tower in the first operating mode and the second operating mode, and the other of the first primary absorption tower and the second primary absorption tower can be regenerated. The regeneration of the first primary absorption tower or the second primary absorption tower can be performed by supplying the process gas treated from the secondary treatment unit.

[0009] In at least certain embodiments, the primary treatment unit can be selectively configured in at least one of the first operating mode and the second operating mode. In at least certain embodiments, the primary treatment unit can continue to treat the process gas when operating in the first operating mode and the second operating mode.

[0010] The process gas supplied to the primary processing unit can be processed by the first primary absorption tower when the primary processing unit is configured to operate in the first operating mode. The first primary absorption tower can be activated in the first operating mode.

[0011] The process gas can be processed by the second primary absorption tower when the primary processing unit is configured to operate in the second operating mode. The second primary absorption tower can be activated in the second operating mode.

[0012] When operating in the first operating mode, the first process gas inlet can be connected to the first primary absorption tower to supply the process gas to the first primary absorption tower for treatment. The first primary absorption tower can be configured to process the process gas when the primary processing unit is operating in the first operating mode. The second primary absorption tower can be regenerated when the primary processing unit is operating in the first operating mode. The second primary absorption tower can be connected to at least one secondary process gas outlet to receive the process gas processed by the secondary processing unit for regenerating the second primary absorption tower. The second primary absorption tower can be regenerated during part or all of the first operating mode. In a variant, the second primary absorption tower can be regenerated independently of the operating mode of the primary processing unit. For example, the second primary absorption tower can be regenerated when the first primary absorption tower is not operating to process the process gas supplied from the primary process gas inlet.

[0013] When operating in the second operating mode, the primary process gas inlet can be connected to the second primary absorption tower to supply process gas to the second primary absorption tower for processing. The second primary absorption tower can be configured to process the process gas when the primary processing unit is operating in the second operating mode. The first primary absorption tower can be regenerated when the primary processing unit is operating in the second operating mode. The first primary absorption tower can be connected to at least one secondary process gas outlet to receive the processed process gas from the secondary processing unit for regenerating the first primary absorption tower. The first primary absorption tower can be regenerated during part or all of the second operating mode. In a variant, at least one of the first primary absorption tower and the second primary absorption tower can be regenerated independently of the operating mode of the primary processing unit. For example, at least one of the first primary absorption tower and the second primary absorption tower can be regenerated when the primary processing unit is not operating to process the process gas supplied from the primary process gas inlet.

[0014] The primary processing unit may include a plurality of primary process gas outlets. The primary processing unit may include a first primary process gas outlet for discharging the processed process gas from the first primary absorption tower. The primary processing unit may include a second primary process gas outlet for discharging the processed process gas from the second primary absorption tower. Alternatively, one or more primary process gas outlets may be suitable for discharging the processed process gas from both the first primary absorption tower and the second primary absorption tower.

[0015] The secondary processing unit can include a plurality of secondary process gas outlets. The secondary processing unit can include a first secondary process gas outlet for supplying the processed process gas to the first primary absorption tower. The secondary processing unit may include a second secondary process gas outlet for supplying the processed process gas to the second primary absorption tower. Alternatively, one or more secondary process gas outlets may be suitable for supplying the processed process gas to both the first primary absorption tower and the second primary absorption tower.

[0016] In at least certain embodiments, the gas treatment device can purify the process gas. More specifically, the gas treatment device can remove contaminants from the process gas.

[0017] In use, the primary treatment unit can operate to remove contaminants from the process gas. In at least certain embodiments, the primary treatment unit can provide a primary purification unit. In at least certain embodiments, the primary treatment unit can consist of a primary air purification unit.

[0018] In use, the secondary treatment unit can operate to remove contaminants from the process gas. In at least certain embodiments, the secondary treatment unit can provide a secondary purification unit. In at least certain embodiments, the secondary treatment unit can consist of a secondary air purification unit.

[0019] In at least certain embodiments, the regeneration of the primary treatment unit can be carried out by supplying the treated process gas received exclusively (i.e., solely) from the secondary treatment unit. Thereby, the need for the primary treatment unit to supply gas for regenerating the first primary absorption tower and the second primary absorption tower can be reduced or eliminated. A primary compressor may be provided to supply untreated process gas to the first primary absorption tower and the second primary absorption tower. The primary compressor may be incorporated into the primary treatment unit or may be separated from the primary treatment unit. Since the regeneration stream for the primary treatment unit can be supplied from the secondary treatment unit, the primary compressor does not need to generate a regeneration stream for the first primary absorption tower and the second primary absorption tower. Usually, the regeneration stream is supplied from the supply stream from the primary compressor, which represents a reduction in the available stream for liquefaction in the downstream system. By supplying the regeneration stream from the secondary treatment unit, the discharge pressure of the primary compressor can be determined according to the required compression of the process gas for the purpose of supply to the primary treatment unit. Thereby, the optimization of the operation of the primary compressor is promoted, and in at least certain embodiments, the primary compressor can be operated more efficiently. This can also reduce or avoid the need to throttle the pressure of the process stream, which can result in energy losses.

[0020] The primary treatment unit and the secondary treatment unit can be arranged parallel to each other.

[0021] When operating in the first operating mode, the gas treatment device can be configured to arrange the first primary absorption tower in fluid communication with the primary process gas inlet and at least one primary process gas outlet. In use, the untreated (feed) process gas is supplied to the first primary absorption tower. The first primary absorption tower is configured to treat the process gas by adsorbing one or more contaminants present in the process gas. The treated process gas can be output from the first primary absorption tower to at least one primary process gas outlet. When operating in the first operating mode, the gas treatment device can be configured to arrange the second primary absorption tower in fluid communication with the secondary treatment unit. In use, the untreated (feed) process gas is supplied to the secondary treatment unit. At least one secondary absorption tower is configured to treat the process gas by adsorbing one or more contaminants present in the process gas. The treated process gas is output from the secondary treatment unit and regenerates the primary treatment unit. The treated process gas is supplied to the second primary absorption tower and regenerates the second primary absorption tower. In at least certain embodiments, the regeneration of the second primary absorption tower can be carried out simultaneously with the first primary absorption tower treating the process gas.

[0022] When operating in the second operating mode, the second primary absorption tower is configured to be arranged in fluid communication with the primary process gas inlet and at least one primary process gas outlet. In use, the untreated (feed) process gas is supplied to the second primary absorption tower. The second primary absorption tower is configured to treat the process gas by adsorbing one or more contaminants present in the process gas. The treated process gas can be output from the second primary absorption tower to at least one primary process gas outlet. The apparatus is configured to arrange the first primary absorption tower in fluid communication with the secondary treatment unit in the second operating mode. In use, the untreated (feed) process gas is supplied to the secondary treatment unit. The untreated (feed) process gas is supplied to the secondary treatment unit to adsorb one or more contaminants. The treated process gas is output from the secondary treatment unit to the primary treatment unit. The treated process gas is supplied to the first primary absorption tower to regenerate the first primary absorption tower. In at least certain embodiments, the regeneration of the first primary absorption tower can be carried out simultaneously with the second primary absorption tower treating the process gas.

[0023] When operating in the first operating mode, a portion of the treated process gas from the first primary absorption tower can be supplied to repressurize the second primary absorption tower after the regeneration of the second primary absorption tower.

[0024] When operating in the second operating mode, a portion of the treated process gas from the second primary absorption tower is supplied to repressurize the first primary absorption tower after the regeneration of the first primary absorption tower.

[0025] When operating in the first operating mode, the second primary absorption tower may be depressurized prior to the regeneration of the second primary absorption tower.

[0026] When operating in the second operating mode, the first primary absorption tower may be depressurized prior to the regeneration of the first primary absorption tower.

[0027] The gas treatment device may include a primary regeneration heater. The primary regeneration heater may be configured to heat the processed process gas from the secondary treatment unit before introducing it into the primary treatment unit.

[0028] The gas treatment device can be selectively configured to regenerate the secondary treatment unit.

[0029] At least one secondary absorption tower may include a first secondary absorption tower and a second secondary absorption tower for treating the process gas. In use, one of the first secondary absorption tower and the second secondary absorption tower is operatively selected to treat the process gas, and the other of the first secondary absorption tower and the second secondary absorption tower can be regenerated. A part of the processed process gas from the selected one of the first secondary absorption tower and the second secondary absorption tower can be output to regenerate the other of the first secondary absorption tower and the second secondary absorption tower.

[0030] The regeneration of the secondary treatment unit can be performed independently of the operating mode of the primary treatment unit. At least one secondary absorption tower may consist of a first secondary absorption tower and a second secondary absorption tower. In use, one of the first secondary absorption tower and the second secondary absorption tower can be operatively selected to treat the process gas supplied to the secondary treatment unit. The processed process gas is output from the secondary treatment unit to the primary treatment unit and can regenerate at least one of the first primary absorption tower and the second primary absorption tower. The other of the first secondary absorption tower and the second secondary absorption tower may be regenerated. The regeneration of the first secondary absorption tower and the second secondary absorption tower can be performed independently of the operation of the primary treatment unit. For example, the first secondary absorption tower and the second secondary absorption tower can periodically repeat one or more treatment (supply) operations and one or more regeneration operations independently of the operating mode of the primary treatment unit.

[0031] The regeneration of the secondary treatment unit can be carried out when the primary treatment unit is online (i.e., while process gas is being supplied to the primary treatment unit for processing), or when the primary treatment unit is offline (i.e., while process gas is not being supplied to the primary treatment unit for processing).

[0032] Alternatively, the regeneration of the secondary treatment unit may be executed in response to the operation of the primary treatment unit. The gas treatment apparatus may be configured to regenerate the secondary treatment unit while the primary treatment unit is operating in a first operating mode or a second operating mode.

[0033] The gas treatment apparatus may include a secondary regeneration heater. The secondary regeneration heater may be configured to heat the processed process gas to regenerate the other one of the first secondary absorption tower and the second secondary absorption tower.

[0034] The gas treatment apparatus can be provided with a primary compressor for compressing the process gas supplied to the primary process gas inlet of the primary treatment unit. Alternatively, or in addition, the gas treatment apparatus can be provided with a secondary compressor for compressing the process gas supplied to the secondary process gas inlet of the secondary treatment unit.

[0035] The gas treatment apparatus may include a primary outlet valve system. The primary outlet valve system can include at least one outlet valve for controlling the supply of the processed process gas from the primary treatment unit. The primary outlet valve system can be configured to selectively connect at least one of the first primary absorption tower and the second primary absorption tower to at least one primary process gas outlet.

[0036] The primary outlet valve system can be configured to selectively connect the secondary treatment unit to one of the first primary absorption tower and the second primary absorption tower to perform regeneration. When operating in the first operating mode, the primary outlet valve system can be configured to connect the first primary absorption tower to at least one primary process gas outlet. When operating in the second operating mode, the primary outlet valve system can be configured to connect the second primary absorption tower to at least one primary process gas outlet.

[0037] When operating in the first operating mode, the primary outlet valve system can be configured to connect the secondary treatment unit to the second primary absorption tower. When operating in the second operating mode, the primary outlet valve system can be configured to connect the secondary treatment unit to the first primary absorption tower.

[0038] The gas treatment device may include a secondary outlet valve system. The secondary outlet valve system can include at least one outlet valve for controlling the supply of the treated process gas from the secondary treatment unit. The secondary outlet valve system can be configured to selectively connect at least one secondary absorption tower to at least one secondary process gas outlet.

[0039] The gas treatment device may include a primary inlet valve system. The primary inlet valve system can include at least one inlet valve for controlling the supply of the untreated process gas to the primary treatment unit. The primary inlet valve system can be configured to selectively connect the primary process gas inlet to at least one of the first primary absorption tower and the second primary absorption tower.

[0040] The primary inlet valve system can be configured to selectively connect the primary process gas inlet to one of the first primary absorption tower and the second primary absorption tower. The primary inlet valve system can be configured to selectively vent process gas from one of the first primary absorption tower and the second primary absorption tower to depressurize the first primary absorption tower and the second primary absorption tower.

[0041] The primary inlet valve system can be configured to connect the first primary absorption tower to the primary process gas inlet when operating in the first operating mode. The primary outlet valve system can be configured to vent the second primary absorption tower when operating in the first operating mode.

[0042] The primary inlet valve system can be configured to connect the second primary absorption tower to the primary process gas inlet when operating in the second operating mode. The primary outlet valve system can be configured to vent the first primary absorption tower when operating in the second operating mode.

[0043] The gas treatment device may include a secondary inlet valve system. The secondary inlet valve system can include at least one inlet valve for controlling the supply of untreated process gas to the secondary treatment unit. The secondary inlet valve system can be configured to selectively connect the secondary process gas inlet to at least one of the first secondary absorption tower and the second secondary absorption tower.

[0044] The secondary inlet valve system can be configured to selectively connect the secondary process gas inlet to one of the first secondary absorption tower and the second secondary absorption tower. The secondary inlet valve system can be configured to selectively vent the process gas from one of the first secondary absorption tower and the second secondary absorption tower. The process gas can be vented to depressurize the first primary absorption tower and the second primary absorption tower.

[0045] The primary treatment unit and the secondary treatment unit can be configured to remove carbon dioxide (CO2) and water (H2O) from the process gas.

[0046] The process gas supplied to the gas treatment device is usually untreated (supply) process gas. The process gas may be air. The air can be taken in from, for example, the atmosphere.

[0047] The primary treatment unit can provide a primary air treatment unit. In at least certain embodiments, the primary air treatment unit may be a primary air purification unit (PAPU).

[0048] The secondary treatment unit can provide a secondary air treatment unit. In at least certain embodiments, the secondary air treatment unit may be a secondary air purification unit (SAPU).

[0049] According to a further aspect of the present invention, a method for controlling a gas treatment apparatus for treating a process gas is provided. The gas treatment apparatus includes a primary treatment unit including a primary process gas inlet for receiving the process gas, a first primary absorption tower and a second primary absorption tower for treating the process gas, and at least one primary process gas outlet for discharging the process gas treated from the first primary absorption tower and the second primary absorption tower, and a secondary treatment unit including a secondary process gas inlet for receiving the process gas, at least one secondary absorption tower for treating the process gas, and at least one secondary process gas outlet for discharging the treated process gas from at least one secondary absorption tower to the primary treatment unit.

[0050] In at least certain embodiments, the method may include selectively operating the primary treatment unit in a first operating mode and a second operating mode.

[0051] When operating in the first operating mode, the first process gas inlet can be connected to the first primary absorption tower to supply untreated process gas to the first primary absorption tower for treatment. The second primary absorption tower can be connected to at least one secondary process gas outlet to receive the process gas treated from the secondary treatment unit for regenerating the second primary absorption tower.

[0052] When operating in the second operating mode, the primary process gas inlet can be connected to the second first absorption tower to supply process gas to the second primary absorption tower for processing. The first primary absorption tower can be connected to at least one secondary process gas outlet to receive the process gas processed by the secondary treatment unit to regenerate the first primary absorption tower.

[0053] The at least one secondary absorption tower can consist of a first secondary absorption tower and a second secondary absorption tower. In use, one of the first secondary absorption tower and the second secondary absorption tower can be operably selected to process the process gas supplied to the secondary treatment unit. The processed process gas is output from the secondary treatment unit to the primary treatment unit and can regenerate at least one of the first primary absorption tower and the second primary absorption tower. The other of the first secondary absorption tower and the second secondary absorption tower may be regenerated. The regeneration of the first secondary absorption tower and the second secondary absorption tower can be performed independently of the operation of the primary treatment unit. For example, the first secondary absorption tower and the second secondary absorption tower can periodically repeat one or more treatment (supply) operations and one or more regeneration operations independently of the operating mode of the primary treatment unit.

[0054] According to one aspect of the present invention, a gas treatment device for treating a process gas is provided. The gas treatment device includes a primary treatment unit and a secondary treatment unit, and the primary treatment unit and the secondary treatment unit are configured to treat the process gas.

[0055] The primary treatment unit includes a primary process gas inlet for receiving the process gas, a first primary absorption tower and a second primary absorption tower for treating the process gas, and at least one primary process gas outlet for discharging the process gas treated from the first primary absorption tower and the second primary absorption tower.

[0056] The secondary treatment unit includes a secondary process gas inlet for receiving the process gas, at least one secondary absorption tower for treating the process gas, and at least one secondary process gas outlet for discharging the treated process gas from the at least one secondary absorption tower to the primary treatment unit.

[0057] In use, the primary process gas inlet is connected to the first primary absorption tower to supply the process gas to the first primary absorption tower for treatment in the first operating mode, and the primary process gas inlet is connected to the second primary absorption tower to supply the process gas to the second primary absorption tower for treatment in the second operating mode.

[0058] In use, the secondary treatment unit is selectively connected to at least one of the first primary absorption tower and the second primary absorption tower, and supplies the treated process gas to at least one of the first primary absorption tower and the second primary absorption tower to regenerate it.

[0059] The gas treatment device can be configured to selectively operate the primary treatment unit in either the first operating mode or the second operating mode. Depending on the selected operating mode, either the first primary absorption tower or the second primary absorption tower can be operated to treat the process gas supplied from the primary process gas inlet.

[0060] The secondary treatment unit can be selectively connected to at least one of the first primary absorption tower and the second primary absorption tower. At least one of the first primary absorption tower and the second primary absorption tower can be regenerated by supplying the treated process gas from the secondary treatment unit.

[0061] The gas treatment device can be selectively configured to regenerate the secondary treatment unit. The regeneration of the secondary treatment unit can be performed independently of the operating mode of the primary treatment unit.

[0062] At least one secondary absorption tower can include a first secondary absorption tower and a second secondary absorption tower. During use, one of the first secondary absorption tower and the second secondary absorption tower is selectively operably selected to process the process gas supplied to the secondary treatment unit. The processed process gas is output from the secondary treatment unit to the primary treatment unit and can regenerate at least one of the first primary absorption tower and the second primary absorption tower. The other of the first secondary absorption tower and the second secondary absorption tower may be regenerated. The regeneration of the first secondary absorption tower and the second secondary absorption tower can be performed independently of the operation of the primary treatment unit. For example, the first secondary absorption tower and the second secondary absorption tower can periodically repeat one or more treatment (supply) operations and one or more regeneration operations independently of the operation mode of the primary treatment unit.

[0063] According to a further aspect of the present invention, a gas treatment device for treating a process gas is provided. The gas treatment device includes a primary treatment unit and a secondary treatment unit, and the primary treatment unit and the secondary treatment unit are configured to treat the process gas.

[0064] The primary treatment unit includes a primary process gas inlet for receiving the process gas, a first primary absorption tower and a second primary absorption tower for treating the process gas, and at least one primary process gas outlet for discharging the processed process gas from the first primary absorption tower and the second primary absorption tower.

[0065] The secondary treatment unit includes a secondary process gas inlet for receiving the process gas, at least one secondary absorption tower for treating the process gas, and at least one secondary process gas outlet for discharging the processed process gas from the at least one secondary absorption tower to the primary treatment unit.

[0066] In at least certain embodiments, the primary treatment unit may be selectively configurable in a first operating mode and a second operating mode.

[0067] When operating in the first operating mode, the first primary absorption tower can be arranged to be in fluid communication with a primary process gas inlet and at least one primary process gas outlet. The second primary absorption tower can be arranged to be in fluid communication with a secondary treatment unit.

[0068] When operating in the second operating mode, the second primary absorption tower can be arranged to be in fluid communication with a primary process gas inlet and at least one primary process gas outlet. The first primary absorption tower can be arranged to be in fluid communication with a secondary treatment unit.

[0069] According to a further aspect of the present invention, there is provided a method of controlling a gas treatment apparatus for treating a process gas. The gas treatment apparatus comprises a primary process gas inlet for receiving the process gas, a first primary absorption tower and a second primary absorption tower for treating the process gas, and at least one primary process gas outlet for discharging the process gas treated from the first primary absorption tower and the second primary absorption tower, which together form a primary treatment unit; a secondary process gas inlet for receiving the process gas, at least one secondary absorption tower for treating the process gas, and at least one secondary process gas outlet for discharging the process gas treated from the at least one secondary absorption tower to the primary treatment unit, which together form a secondary treatment unit. The method comprises in a first operating mode, connecting the primary process gas inlet to the first primary absorption tower to supply untreated process gas to the first primary absorption tower for treatment; in a second operating mode, connecting the primary process gas inlet to the second primary absorption tower to supply process gas to the second primary absorption tower for treatment; and connecting the secondary treatment unit to at least one of the first primary absorption tower and the second primary absorption tower to supply the treated process gas for regenerating at least one of the first primary absorption tower and the second primary absorption tower.

[0070] The method may include selectively operating the primary processing unit in either a first operating mode or a second operating mode. Depending on the selected operating mode, either the first primary absorption tower or the second primary absorption tower can be operated to process the process gas supplied from the primary process gas inlet.

[0071] The method may include selectively connecting the secondary processing unit to at least one of the first primary absorption tower and the second primary absorption tower. At least one of the first primary absorption tower and the second primary absorption tower can be regenerated by supplying the processed process gas from the secondary processing unit.

[0072] The at least one secondary absorption tower may consist of a first secondary absorption tower and a second secondary absorption tower. The method can include selecting one of the first secondary absorption tower and the second secondary absorption tower to process the process gas supplied to the secondary processing unit. The processed process gas is output from the secondary processing unit to the primary processing unit and can regenerate at least one of the first primary absorption tower and the second primary absorption tower. The other of the first secondary absorption tower and the second secondary absorption tower may be regenerated. The regeneration of the first secondary absorption tower and the second secondary absorption tower can be performed independently of the operation of the primary processing unit. For example, the first secondary absorption tower and the second secondary absorption tower can periodically repeat one or more processing (supply) operations and one or more regeneration operations independently of the operating mode of the primary processing unit.

[0073] According to a further aspect of the present invention, there is provided an electronic control unit configured to control a gas treatment apparatus to execute the method(s) described herein. The electronic control unit consists of at least one electronic processor and at least one memory device. A set of computing instructions is stored in the memory device. When executed by the at least one electronic processor, the computing instructions cause the at least one electronic processor to execute the method(s) described herein.

[0074] According to a further aspect of the present invention, there is provided a liquid air energy storage plant comprising the gas treatment apparatus described herein.

[0075] Unless otherwise indicated (either implicitly, explicitly, or due to incompatibility), references herein to components being connected to each other or in fluid communication with each other are understood to mean that the components are in fluid communication with each other such that fluid is transmitted between the components during use. The fluid may include, for example, one or more of untreated (feed) process gas, treated process gas, and regeneration gas. As an example, a reference to a process gas inlet being connected to or in fluid communication with an absorption tower (within a primary treatment unit or a secondary treatment unit) means that the process gas inlet is in fluid communication with the absorption tower and is capable of conveying process gas to the absorption tower. As a further example, a reference to an absorption tower (within a primary treatment unit or a secondary treatment unit) being connected to or in fluid communication with a process gas outlet means that the absorption tower is in fluid communication with the process gas outlet and is capable of conveying treated process gas to the process gas outlet. These examples are non-limiting, and other examples of components being fluidly connected to each other are within the scope of the present application.

[0076] The valves described herein are selectively operable to establish or inhibit fluid connections. Alternatively or in addition, the valves can effect variable or proportional control of the fluid. The valve can comprise, for example, a variable valve or a proportional valve for controlling the supply of fluid within the gas treatment apparatus.

[0077] The control unit or control device described in this specification may preferably consist of a computing device having one or more electronic processors. The system may consist of a single control unit or electronic control device, or alternatively, different functions of the control device may be embodied in, or alternatively, hosted by, different control units or control devices. As used herein, the terms "control device" or "control unit" are understood to include both a single control unit or control device and a plurality of control units or control devices that operate collectively to provide any control function. To configure the control device or control unit, a suitable set of instructions can be provided that, when executed, cause the control technology defined herein to be implemented in the control unit or computing device. The set of instructions can preferably be embedded in one or more electronic processors. Alternatively, the set of instructions can be provided as software stored on one or more memories associated with the control device so as to be executed on the computing device. The control unit or control device can be implemented in software executed on one or more processors. One or more other control units or control devices can be implemented in software executed on one or more processors, optionally the same one or more processors as the first control device. Other suitable configurations can also be used.

[0078] Within the scope of this application, it is explicitly intended that the various aspects, embodiments, examples, and alternatives described in the previous paragraphs, the claims, and / or the following description and drawings, particularly their individual features, can be taken independently or in any combination. That is, all embodiments and / or features of any embodiment can be combined in any way and / or combination, provided that such features are not incompatible. The applicant reserves the right to amend the originally filed claims or to file new claims accordingly. This also includes the right to amend the originally filed claims to depend on and / or incorporate features of other claims that were not originally claimed as such.

Brief Description of the Drawings

[0079]

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Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

[0080] Next, one or more embodiments of the present invention will be described by way of example only with reference to the accompanying drawings.

[0081] All values described in this specification for physical quantities such as pressure, temperature, mass flow rate, velocity, etc. are all exemplary and are intended to assist in the understanding of the present invention. Those skilled in the art will understand that a wide range of values for these physical quantities are possible depending on the specific scale or embodiment of the present invention and the requirements of the user, and that the present invention is not limited to the described values unless otherwise stated.

[0082] Hereinafter, a gas treatment device 1 for treating a process gas according to an embodiment of the present invention will be described with reference to the accompanying drawings. The gas treatment device 1 is configured to be used in a liquid air energy storage plant.

[0083] As described in this specification, the gas treatment device 1 is configured to treat a process gas, typically to remove contaminants by adsorbing the contaminants. In this embodiment, the process gas is air that is compressed at a pressure higher than atmospheric pressure and supplied to the gas treatment device 1. The gas treatment device 1 is configured to remove carbon dioxide (CO2) and water (H2O) in the air. In this specification, the process gas supplied to the gas treatment device 1 is referred to as an untreated (supply) process gas. In this specification, the process gas discharged from the gas treatment device 1 is referred to as a treated process gas. The untreated (supply) process gas may be referred to as a wet process gas, and the treated process gas may be referred to as a dry process gas. It will be understood that the process gas may undergo additional treatment processes before and / or after being supplied to the gas treatment device 1. It will be understood that the gas treatment device 1 and the treatment method described in this specification can also be used for treating process gases other than air.

[0084] As shown in FIG. 1, the gas treatment apparatus 1 comprises a primary treatment unit 2 and a secondary treatment unit 3. The primary treatment unit 2 is configured to operate as a primary air purification unit (PAPU), and the secondary air treatment unit 3 is configured to operate as a secondary air purification unit (SAPU). The primary treatment unit 2 is configured to receive untreated (supply) process gas. The primary treatment unit 2 functions as a primary air purification unit, and the secondary treatment unit 3 functions as a secondary air purification unit. The primary treatment unit 2 removes carbon dioxide (CO2) and water (H2O) from the untreated (supply) process gas and discharges the treated process gas. The secondary treatment unit 3 is configured to supply a regeneration gas for regenerating the primary treatment unit 2. The primary treatment unit 2 is configured to receive untreated (supply) process gas. The untreated (supply) gas is treated in the secondary treatment unit 3 to remove contaminants. In this embodiment, the regeneration gas is air treated to remove carbon dioxide (CO2) and water (H2O). In this embodiment, both the primary treatment unit 2 and the secondary treatment unit 3 are configured to treat the same process gas. The primary treatment unit 2 and the secondary treatment unit 3 can be configured to receive process gas from a common source, for example, the same compressor. In this embodiment, the primary treatment unit 2 and the secondary treatment unit 3 are configured to receive untreated (supply) process gas from separate sources. Thereby, the supply of untreated (supply) process gas to the primary treatment unit 2 and the secondary treatment unit 3 can be independently controlled, for example, it becomes possible to supply untreated (supply) process gas at different pressures.

[0085] The electronic control unit 5 is provided to control the operation of the gas treatment device 1. As described in this specification, the primary treatment unit 2 of the gas treatment device 1 can be selectively operated in a first operation mode and a second operation mode. The electronic control unit 5 is selectively set so that the primary treatment unit 2 operates in the first operation mode and the second operation mode. As shown in FIG. 2, the electronic control unit 5 includes at least one electronic processor 6 and a system memory 7. The at least one electronic processor 6 has at least one input 8 and at least one output 9. The at least one electronic processor 6 is configured to output a control signal SOUT-n for controlling the operation of the gas treatment device 1. The control unit 5 may be a dedicated control device or a general-purpose arithmetic device that executes an application for controlling the operation of the gas treatment device 1. A set of calculation instructions is stored in the system memory 7. When executed by the at least one electronic processor 6, the calculation instructions cause the at least one electronic processor 6 to implement the method(s) described in this specification.

[0086] The regenerated gas supply conduit 4 is provided to supply regenerated gas from the secondary treatment unit 3 to the primary treatment unit 2. The primary treatment unit 2 includes a primary process gas inlet 10 for receiving untreated (supply) process gas, at least one primary process gas outlet 11 for discharging the treated process gas, a first primary absorption tower 12, and a second primary absorption tower 13. The first primary absorption tower 12 and the second primary absorption tower 13 are configured to treat the process gas. The first primary absorption tower 12 and the second primary absorption tower 13 are arranged in parallel with each other. The first primary absorption tower 12 consists of a first primary adsorption container 14-1 including a first primary adsorption bed 15-1. The second primary absorption tower 13 consists of a second primary adsorption container 14-2 including a second primary adsorption bed 15-2. In this embodiment, the first primary absorption tower 12 and the second primary absorption tower 13 have the same configuration. The configurations of the first primary absorption tower 12 and the second primary absorption tower 13 will be described in more detail in this specification with reference to FIGS. 3A and 3B.

[0087] As shown in FIG. 1, the primary processing unit 2 includes a primary inlet valve system 16 configured to selectively connect the primary process gas inlet 10 to the first primary absorption tower 12 and the second primary absorption tower 13, and a primary outlet valve system 19 configured to selectively connect the first primary absorption tower 12 and the second primary absorption tower 13 to the primary process gas outlet 11. In the first operating mode, the primary inlet valve system 16 is configured to connect the primary process gas inlet 10 to the first primary absorption tower 12 and connect the first primary absorption tower 12 to the primary process gas outlet 11. In the second operating mode, the primary inlet valve system 16 is configured to connect the primary process gas inlet 10 to the second primary absorption tower 13 and connect the second primary absorption tower 13 to the primary process gas outlet 11. The primary inlet valve system 16 consists of a plurality of primary inlet control valves 20-n, and the primary outlet valve system 19 consists of a plurality of primary outlet control valves 23-n.

[0088] The primary inlet control valve 20-n is configured to control the supply of untreated (feed) process gas from the primary process gas inlet 10 to the first primary absorption tower 12 and the second primary absorption tower 13. Each of the primary inlet control valves 20-n is independently controllable by the control unit 5. Each of the primary inlet control valves 20-n comprises an actuator such as a solenoid operable in response to a valve control signal. The primary inlet control valve 20-n is a two-way valve in this embodiment, but other types of valves may be used. For example, the primary inlet control valve 20-n may be a three-way valve. In this embodiment, the primary inlet valve system 16 consists of an array of six primary inlet control valves 20-n arranged in pairs for the first inlet branch 21-1, the second inlet branch 21-2, and the third inlet branch 21-3. The primary inlet valve system 16 may consist of any other configuration of the primary inlet control valves 20-n configured to control the supply of untreated (feed) process gas from the primary process gas inlet 10 to at least one of the first primary absorption tower 12 and the second primary absorption tower 13. The primary process gas inlet 10 is connected to the first inlet branch 21-1 between the first primary inlet control valve 20-1 and the second primary inlet control valve 20-2. The first primary inlet control valve 20-1 and the second primary inlet control valve 20-2 are selectively opened and closed to arrange the primary process gas inlet 10 in fluid communication with one (or both) of the first primary absorption tower 12 and the second primary absorption tower 13. The primary process gas vent 22 is connected to the second inlet branch 21-2 between the third primary inlet control valve 20-3 and the fourth primary inlet control valve 20-4. The primary process gas vent 22 is also connected to the third inlet branch 21-3 between the fifth primary inlet control valve 20-5 and the sixth primary inlet control valve 20-6. The first primary absorption tower 12 and the second primary absorption tower 13 can be controllably vented through the primary process gas vent 22. The primary inlet valve system 16 may consist of any other configuration of the primary inlet control valves 20-n configured to controllably vent the first primary absorption tower 12 and the second primary absorption tower 13 via the primary process gas vent 22. Various configurations of the primary inlet control valves 20-n are conceivable.For example, the fifth primary inlet control valve 20-5 and the sixth primary inlet control valve 20-6 may be omitted. The third primary inlet control valve 20-3 and the fourth primary inlet control valve 20-4 may be configured to reduce the pressure of the first primary absorption tower 12 and the second primary absorption tower 13.

[0089] Each primary inlet control valve 20-n has a valve flow coefficient (Cv) representing the flow rate capacity in the fully open operating state with respect to the pressure drop across the valve. In the present embodiment, the primary inlet control valves 20-n have different valve flow coefficients (Cv). The primary inlet control valves 20-n can be configured to implement different flow rate capabilities for different operating processes. In the present embodiment, the valve flow coefficients (Cv) of the third primary inlet control valve 20-3 and the fourth primary inlet control valve 20-4 are smaller than the valve flow coefficients (Cv) of the fifth primary inlet control valve 20-5 and the sixth primary inlet control valve 20-6. As described in this specification, the third primary inlet control valve 20-3 and the fourth primary inlet control valve 20-4 are opened to reduce the pressure of the corresponding first primary adsorption container 14-1 and the second primary adsorption container 14-2, and the fifth primary inlet control valve 20-5 and the sixth primary inlet control valve 20-6 are opened to purge (regenerate) the corresponding first primary adsorption bed 15-1 and the second primary adsorption bed 15-2. The smaller of the valve flow coefficients (Cv) of the third primary inlet control valve 20-3 and the fourth primary inlet control valve 20-4 maintains a low gas flow rate for pressure reduction. Thereby, a large downward force is applied to the first primary adsorption bed 15-1 and the second primary adsorption bed 15-2, and a high gas flow rate that may damage the support grid for supporting the adsorption beds 15-1, 15-2 can be avoided. The first primary adsorption bed 15-1 and the second primary adsorption bed 15-2 are preferably close to atmospheric pressure before starting regeneration. Otherwise, when the purge (regeneration) step valve is opened, the gas flow rate increases, so the temporary gas flow rate may become very large.

[0090] Alternatively, one or more of the primary inlet control valves 20-n may consist of variable control valves. The third primary inlet control valve 20-3 and the fourth primary inlet control valve 20-4 may each consist of a variable flow control valve operable to adjust or regulate the flow capacity. The third primary inlet control valve 20-3 and the fourth primary inlet control valve 20-4 can be configured to provide a first flow capacity for pressure reduction and a second flow capacity for purge (regeneration). The first flow capacity may be smaller than the second flow capacity. Alternatively, or in addition, the third primary inlet control valve 20-3 and the fourth primary inlet control valve 20-4 can be opened and closed pulsatingly (pulse width modulation) to adjust the flow capacity. The fifth primary inlet control valve 20-5 and the sixth primary inlet control valve 20-6 can be optionally omitted.

[0091] The primary outlet control valve 23-n is configured to control the supply of the processed process gas from at least one of the first primary absorption tower 12 and the second primary absorption tower 13 to at least one of the other primary absorption tower and the primary process gas outlet 11. Each of the primary outlet control valves 23-n can be independently controlled by the control unit 5. Each of the primary outlet control valves 23-n comprises an actuator such as a solenoid operable in response to a valve control signal. The primary outlet control valve 23-n is a two-way valve in this embodiment, but other types of valves may be used. For example, the primary outlet control valve 23-n may be a three-way valve. In this embodiment, the primary outlet valve system 19 consists of an array of five primary outlet control valves 23-n arranged at the first outlet branch 24-1, the second outlet branch 24-2, and the third outlet branch 24-3. The primary outlet valve system 19 may consist of any other configuration of the primary outlet control valve 23-n configured to control the supply of the processed process gas from at least one of the first primary absorption tower 12 and the second primary absorption tower 13 to at least one of the other primary absorption tower and the primary process gas outlet 11. The primary process gas outlet 11 is connected to the first outlet branch 24-1 between the first primary outlet control valve 23-1 and the second primary outlet control valve 23-2. The first primary outlet control valve 23-1 and the second primary outlet control valve 23-2 are opened and closed to arrange one (or both) of the first primary absorption tower 12 and the second primary absorption tower 13 in fluid communication with the primary process gas outlet 11. The regeneration gas supply conduit 4 is connected to the second outlet branch 24-2 between the third primary outlet control valve 23-3 and the fourth primary outlet control valve 23-4. The third primary outlet control valve 23-3 and the fourth primary outlet control valve 23-4 are selectively opened and closed to arrange the regeneration gas supply conduit 4 in fluid communication with one (or both) of the first primary absorption tower 12 and the second primary absorption tower 13. The third primary outlet control valve 23-3 and the fourth primary outlet control valve 23-4 can both be closed to suppress the supply of the processed process gas from the regeneration gas supply conduit 4 to the first primary absorption tower 12 and the second primary absorption tower 13.As described herein, the third primary outlet control valve 23-3 and the fourth primary outlet control valve 23-4 are activated to control the regeneration of the first primary absorption tower 12 and the second primary absorption tower 13. The third outlet branch 24-3 forms a re-pressurization conduit for selectively re-pressurizing the first primary absorption tower 12 and the second primary absorption tower 13. The fifth primary outlet control valve 23-5 is selectively provided in the third outlet branch 24-3 to establish fluid communication between the first primary absorption tower 12 and the second primary absorption tower 13. The fifth primary outlet control valve 23-5 is actuated to control re-pressurization of one of the first primary absorption tower 12 and the second primary absorption tower 13 from the other of the first primary absorption tower 12 and the second primary absorption tower 12, 13. The primary outlet valve system 19 may also consist of any other configuration of the primary outlet control valve 23-n arranged to fluidly communicate the regeneration gas supply conduit 4 with one (or both) of the first primary absorption tower 12 and the second primary absorption tower 13 and configured to establish fluid communication between the first primary absorption tower 12 and the second primary absorption tower 13.

[0092] The regeneration gas supply conduit 4 is provided with a primary regeneration heater 25 for heating the regeneration gas supplied to the primary treatment unit 2. In the present embodiment, the primary regeneration heater 25 is provided for heating the regeneration gas supplied from the secondary treatment unit 3. The first heater control device 26 is provided for controlling the operation of the primary regeneration heater 25. The first heater control device 26 includes at least one electronic processor having at least one electrical input for receiving a corresponding first primary temperature signal and a second primary temperature signal from the first temperature sensor 27 and the second first temperature sensor 28. The first heat control device 26 may be a separate control device or may be incorporated into the control unit 5. The first primary temperature sensor 27 is configured to measure the first operating temperature T1 of the first primary absorption tower 12, and the second primary temperature sensor 28 is configured to measure the second operating temperature T2 of the second primary absorption tower 13. The regeneration gas supply conduit 4 is provided with a primary regeneration control valve 29 for controlling the supply of the processed process gas from the secondary treatment unit 3. The primary regeneration control valve 29 is a two-way valve that can be selectively opened and closed. The primary regeneration control valve 29 is a pneumatic valve in the present embodiment.

[0093] The secondary treatment unit 3 includes a secondary process gas inlet 30 for receiving the untreated (supply) process gas, at least one secondary process gas outlet 31 for discharging the treated process gas, a first secondary absorption tower 32, and a second secondary absorption tower 33. The first secondary absorption tower 32 and the second secondary absorption tower 33 are configured to treat the process gas. As shown in FIG. 1, the first secondary absorption tower 32 and the second secondary absorption tower 33 are arranged in parallel. The first secondary absorption tower 32 comprises a first secondary adsorption container 34-1 including a first adsorption bed 35-1. The second secondary absorption tower 33 comprises a second secondary adsorption container 34-2 including a second adsorption bed 35-2. In this embodiment, the first secondary absorption tower 32 and the second secondary absorption tower 33 have a similar configuration. The first secondary absorption tower 32 and the second secondary absorption tower 33 have substantially the same configuration as the first primary absorption tower 12 and the second primary absorption tower 13 described in this specification. Optionally, the volumes of the first secondary absorption tower 32 and the second secondary absorption tower 33 may be smaller than the volumes of the first primary absorption tower 12 and the second primary absorption tower 13.

[0094] The secondary treatment unit 3 includes a secondary inlet valve system 36 configured to selectively connect the secondary process gas inlet 30 to the first secondary absorption tower 32 and the second secondary absorption tower 33, and a secondary outlet valve system 39 configured to selectively connect the first secondary absorption tower 32 and the second secondary absorption tower 33 to the secondary process gas outlet 31. The secondary inlet valve system 36 comprises a plurality of secondary inlet control valves 40-n, and the secondary outlet valve system 39 comprises a plurality of secondary outlet control valves 43-n.

[0095] The secondary inlet control valve 40-n is configured to control the supply of untreated (feed) process gas from the secondary process gas inlet 30 to the first secondary absorption tower 32 and the second secondary absorption tower 33. Each of the secondary inlet control valves 40-n can be independently controlled by the control unit 5. Each of the secondary inlet control valves 40-n comprises an actuator such as a solenoid operable in response to a valve control signal. The secondary inlet control valve 40-n is a two-way valve in this embodiment, but other types of valves may be used. For example, the secondary inlet control valve 40-n may be a three-way valve. In this embodiment, the secondary inlet valve system 36 comprises an array of six secondary inlet control valves 40-n arranged in pairs with respect to the first inlet branch 41-1, the second inlet branch 41-2, and the third inlet branch 41-3. The secondary inlet valve system 36 can consist of any other configuration of the secondary inlet control valves 40-n configured to control the supply of untreated (feed) process gas from the secondary process gas inlet 30 to the first secondary absorption tower 32 and the second secondary absorption tower 33. The secondary process gas inlet 30 is connected to the first inlet branch 41-1 between the first secondary inlet control valve 40-1 and the second secondary inlet control valve 40-2. The first secondary inlet control valve 40-1 and the second secondary inlet control valve 40-2 are selectively opened and closed and arranged to place the secondary process gas inlet 30 in fluid communication with one (or both) of the first secondary absorption tower 32 and the second secondary absorption tower 33. The secondary process gas vent 42 is connected to the second inlet branch 41-2 between the third secondary inlet control valve 40-3 and the fourth secondary inlet control valve 40-4. The secondary process gas vent 42 is also connected to the third inlet branch 41-3 between the fifth secondary inlet control valve 40-5 and the sixth secondary inlet control valve 40-6. The first secondary absorption tower 32 and the second secondary absorption tower 33 can be controllably vented through the secondary process gas vent 42. The secondary inlet valve system 36 can consist of any other configuration of the secondary inlet control valves 40-n configured to controllably vent the first secondary absorption tower 32 and the second secondary absorption tower 33 via the secondary process gas vent 42.

[0096] The secondary outlet control valve 43-n is configured to control the supply of the processed process gas from at least one of the first secondary absorption tower 32 and the second secondary absorption tower 33 to the other secondary absorption tower or the secondary process gas outlet 31. The secondary process gas outlet 31 is connected to the regenerated gas supply conduit 4 and, in use, is operable to supply the processed process gas from the secondary treatment unit 3 to the primary treatment unit 2 to regenerate the first primary absorption tower 12 and the second primary absorption tower 13. Each of the secondary outlet control valves 43-n is independently controllable by the control unit 5. Each of the secondary outlet control valves 43-n comprises an actuator such as a solenoid operable in response to a valve control signal. The secondary outlet control valve 43-n is a two-way valve in this embodiment, but other types of valves may be used. For example, the secondary outlet control valve 43-n may be a three-way valve. In this embodiment, the secondary outlet valve system 39 comprises an array of five secondary outlet control valves 43-n disposed at the first outlet branch 44-1, the second outlet branch 44-2, and the third outlet branch 44-3. The secondary outlet valve system 39 may be composed of any other arrangement of the secondary outlet control valves 43-n configured to control the supply of the processed process gas from at least one of the first secondary absorption tower 32 and the second secondary absorption tower 33 to the other secondary absorption tower or the secondary process gas outlet 31. The secondary process gas outlet 31 is connected to the first outlet branch 44-1 between the first secondary outlet control valve 43-1 and the second secondary outlet control valve 43-2. The first secondary outlet control valve 43-1 and the second secondary outlet control valve 43-2 are selectively opened and closed to arrange one (or both) of the first secondary absorption tower 32 and the second secondary absorption tower 33 in fluid communication with the secondary process gas outlet 31. The first secondary outlet control valve 43-1 and the second secondary outlet control valve 43-2 can both be closed to suppress the supply of the processed process gas to the primary treatment unit 2.

[0097] The heater supply conduit 37 is provided to supply the process gas processed by the secondary regenerative heater 45 from one (or both) of the first secondary absorption tower 32 and the second secondary absorption tower 33. The heater supply conduit 37 forms a loop between the secondary process gas outlet 31 and the second outlet branch 44-2 of the secondary outlet valve system 39. The first end of the heater supply conduit 37 is connected to the second outlet branch 44-2 between the third secondary outlet control valve 43-3 and the fourth secondary outlet control valve 43-4, and the second end of the heater supply conduit 37 is connected to the secondary process gas outlet 44-2. The secondary regeneration control valve 49 is provided in the heater supply conduit 37 to control the supply of the processed process gas to the secondary regenerative heater 45. The supply of the processed process gas to the secondary regenerative heater 45 can be controlled to promote the regeneration of the first secondary absorption tower 32 and the second secondary absorption tower 33. Instead, the second end of the heater supply conduit 37 may be connected to an additional outlet branch (not shown) having a configuration similar to that of the first outlet branch 44-1 or the second outlet branch 44-2, and the second end of the heater supply conduit 37 may be connected between two additional outlet control valves in a configuration similar to the connection of the first end of the heater supply conduit 37 to the second outlet branch 44-2. The fifth secondary outlet control valve 43-5 is selectively provided in the third outlet branch 44-3 to establish fluid communication between the first secondary absorption tower 32 and the second secondary absorption tower 33. The fifth secondary outlet control valve 43-5 is operated to control the recompression of one of the first secondary absorption tower 32 and the second secondary absorption tower 33 from the other of the first secondary absorption tower 32 and the second secondary absorption tower 33. The secondary outlet valve system 39 may consist of any other configuration of the secondary outlet control valve 43-n configured to supply the processed process gas to the secondary regenerative heater 45 and establish fluid communication between the first secondary absorption tower 32 and the second secondary absorption tower 33.

[0098] The second heater control device 46 is provided to control the operation of the secondary regeneration heater 45. The second heater control device 46 may be provided integrally with the control unit 5 or may be an individual control device. The second heater control device 46 includes at least one electronic processor having at least one electrical input for receiving corresponding first and second secondary temperature signals from the first secondary temperature sensor 47 and the second secondary temperature sensor 48. The first secondary temperature sensor 47 is configured to measure the first operating temperature T1 of the first secondary absorption tower 32, and the second secondary temperature sensor 48 is configured to measure the second operating temperature T2 of the second secondary absorption tower 33.

[0099] The untreated (feed) process gas to the primary treatment unit 2 is cooled to the summer peak temperature of 33.4 °C and then supplied from the primary compressor 52, preferably at a supply pressure above the ambient pressure of 15 barg. The regeneration of the primary treatment unit 2 is carried out in a low-energy temperature swing mode using the regeneration gas depressurized from the secondary treatment unit 3 operating at a supply pressure of 3 barg to a pressure slightly higher than the ambient pressure. The secondary treatment unit 3 is supplied with ambient air compressed by a dedicated secondary compressor 53. The air to the primary treatment unit 2 and the secondary treatment unit 3 is independently cooled to 5 °C using a refrigerant cycle to reduce the moisture content. An economizer heat exchanger is used to suppress the power consumption. The primary treatment unit 2 and the secondary treatment unit 3 are provided to reduce the contents of carbon dioxide (CO2) and water (H2O) in the process gas. In the present embodiment, the primary treatment unit 2 and the secondary treatment unit 3 sufficiently reduce the contents of carbon dioxide (CO2) and water (H2O) in the process gas, for example, reducing or preventing freezing at a low temperature at the cold end of the process implemented by a storage plant.

[0100] The primary compressor 52 consists of a primary aftercooler 54. The process gas is discharged from the primary aftercooler 54 and guided into a primary cooler 55 (schematically shown in FIG. 4). The process gas is preferably saturated air and is first cooled by an economizer heat exchanger 56. As a result, the temperature of the process gas drops to about 17°C, and a part of the water vapor condenses. The process gas is further cooled to a temperature of about 5°C against the refrigerant in a refrigerant heat exchanger 57. The condensed water is separated using a lossless water separator / drain 58 and is discharged as waste from the gas treatment device 1 or recycled into another system installed in parallel with the gas treatment device 1. The cooled process gas returns through the opposite side of the economizer heat exchanger 56 and is reheated. As a result, the process gas is reheated and then sent to the primary treatment unit 2. The economizer heat exchanger 56 and the refrigerant heat exchanger 57 condense a considerable portion of water from the air and reduce the temperature below that discharged from the primary aftercooler 54. The warm end temperature difference ΔT of the economizer heat exchanger 56 is typically about 10°C. As an example, the peak (summer) temperature of 33.4°C from the aftercooler of the primary compressor 52 becomes the supply temperature of 23.4°C to the adsorption vessel 14-1. Therefore, the temperature of 23.4°C becomes the design temperature of the adsorption process performed in the primary treatment unit 2. If the economizer heat exchanger 56 is more efficient than expected and the temperature difference ΔT is less than 10°C, it results in savings in refrigerant duty. However, in this case, the temperature of the process gas supplied to the primary treatment unit 2 may be higher. In this scenario, a part of the process gas exiting the water separator / drain 58 is bypassed around the economizer heat exchanger 56 to achieve the target process gas temperature (about 23.4°C in this embodiment) of the primary treatment unit 2. A bypass valve 66 is provided to controllably bypass the economizer heat exchanger 56. The temperature of the process gas exiting the economizer heat exchanger 56 is measured by a temperature sensor 67 that communicates with a bypass control device 65 configured to open and close the bypass valve 66. The bypass valve 66 can be opened by the bypass control device 65 when the process gas temperature exceeds the target process gas temperature (e.g., 23.4°C).When the process gas temperature is below the target operating temperature, the bypass valve 66 is closed (or maintained in a closed state). Instead, the more effective performance of the economizer heat exchanger 56 can be utilized to reduce the heat load on the refrigerant heat exchanger 57. Fig. 4 shows the refrigerant loop 59 of the refrigerant heat exchanger 57. The refrigerant heat exchanger 57 is connected to a refrigerant liquid / vapor separator tank 60, a refrigerant compressor 61, a refrigerant bypass valve 62, an air-cooled refrigerant condenser 63, and an expansion valve 64.

[0101] When the temperature of the process gas supplied from the primary aftercooler 54 exceeds the target supply temperature (33.4 °C in this embodiment), the bypass valve 66 is opened to maintain the process gas temperature to the primary processing unit 2 at the target operating temperature of 23.4 °C. However, as a result, the temperature difference ΔT at the warm end of the economizer heat exchanger 56 may become larger than 10 °C. As a result, the load on the refrigerant loop 59 may increase. When the refrigerant duty is limited, the available cooling can be used to condense water rather than trying to cool the process gas temperature to the target operating temperature for supplying to the primary processing unit 2. If the refrigerant duty is too high, the temperature of the air after the moisture separator / drain 58 will clearly rise. The temperature of the process gas exiting the moisture separator / drain 58 may be measured by a temperature sensor 68 that communicates with the bypass control device 65. The determination that the temperature is rising can be used to ignore the bypass control device 65 to close the bypass valve 66. The bypass control device 65 can define a temperature setpoint of, for example, 7 °C. When the temperature exceeds the set temperature, the bypass control device 65 is configured to close the bypass valve 66.

[0102] The refrigerant loop 59 evaporates the refrigerant in the refrigerant heat exchanger 57 to cool the process gas. The gaseous refrigerant is subsequently compressed by the refrigerant compressor 61, then cooled and condensed with respect to the ambient air. The temperature of the refrigerant is subsequently further reduced by isenthalpic flash expansion via the expansion valve 64 before being returned to the refrigerant heat exchanger 57. The refrigerant bypass valve 62 is used to prevent the cooling by the refrigerant unit from becoming excessive at low loads and the water in the process gas in the refrigerant heat exchanger 57 from freezing. The feed-forward control of the refrigerant unit is provided when the process gas flow rate from the primary compressor 52 decreases rapidly to prevent subcooling and freezing of the water in the refrigerant heat exchanger 57.

[0103] The process gas from the primary cooler 55 is subsequently sent to the primary treatment unit 2. As described above, the primary treatment unit 2 is a two-bed low thermal energy adsorption process for removing water (H2O). As shown in FIG. 1, the primary treatment unit 2 consists of a first primary absorption tower 12 and a second primary absorption tower 13. In the present embodiment, the primary treatment unit 2 is configured to reduce the moisture (H2O) in the process gas to less than dew point -100 °C and the time-averaged carbon dioxide (CO2) to less than 0.1 ppb.

[0104] The first primary absorption tower 12 and the second primary absorption tower 13 of the primary treatment unit 2 have the same configuration. For the sake of brevity, the configuration of the first primary absorption tower 12 will be described in this specification. It will be understood that the second primary absorption tower 13 also has substantially the same configuration. The process gas from the primary cooler 55 is supplied to one of the first primary absorption tower 12 and the second primary absorption tower 13 at a time, during which the other of the first primary absorption tower 12 and the second primary absorption tower 13 is regenerated. The first primary absorption tower 12 consists of a first primary adsorption bed 15-1 disposed in the first primary adsorption vessel 14-1. The second primary absorption tower 13 consists of a second primary adsorption bed 15-2 disposed in the second primary adsorption vessel 14-2. The first adsorption bed 15-1 and the second adsorption bed 15-2 are configured to mainly remove water (H2O) and carbon dioxide (CO2) from the process gas. In practice, the first primary absorption tower 12 and the second primary absorption tower 13 can also at least partially remove one or more of the following Nox, Sox, HCl, C 4+ Other components including one or more of hydrocarbons and acetylene (C2H2) can also be removed at least partially. FIGS. 3A and 3B show two examples of the packed bed layer and the in-bed sensors in the vessel 70. The upward flow direction of the process gas through the first primary absorption tower 12 during processing is indicated by continuous arrows, and the downward flow direction of the regeneration gas through the first primary absorption tower 12 is indicated by intermittent arrows.

[0105] In the standard / default design shown in FIG. 3A, the first primary adsorption bed 15-1 is composed of at least one adsorption layer. In the present embodiment, the at least one adsorption layer is composed of a first adsorption layer 73 and a second adsorption layer 74. The first adsorption layer 73 is composed of beads of an adsorbent. The primary adsorption bed 15-1 may be composed of an additional layer of other materials such as ceramic beads (not shown). The ceramic beads can be provided at the bottom of the first primary adsorption bed 15-1 to knock out water droplets that may be present in the incoming air stream and prevent them from adhering to the adsorbent and damaging the active substance. Since the upstream primary cooler 55 makes the relative humidity of the air considerably lower than 100%, there should be no water droplets under normal operation. However, when the gas treatment apparatus 1 is started in a state where the ambient temperature is low (for example, less than 5°C), water may condense in the upstream piping before reaching the operating temperature, and water droplets may move onto the first primary adsorption bed 15-1.

[0106] In the present embodiment, the first adsorption layer 73 preferably consists of activated alumina. The main purpose of activated alumina is to remove water (H2O) from the process gas, and it is usually removed up to a maximum dew point of -40°C. Particularly when base-treated with potassium carbonate (K2CO3) or sodium carbonate (Na2CO3), activated alumina can also remove a part of carbon dioxide (CO2) from the process gas. Carbon dioxide (CO2) reacts with basic compounds in the presence of water (H2O) to convert carbonates to bicarbonates. The chemical reaction formula is as follows:

[0107]

Chemical formula

[0108] This chemical reaction becomes reversible by applying heat during the regeneration process, dissociating carbon dioxide (CO2) from the alumina.

[0109] The dried process gas that exits the activated alumina layer of the first primary adsorption bed 15-1 passes through the second adsorption layer 74. In the present embodiment, the second adsorption layer 74 is composed of a molecular sieve such as 13X molecular sieve, that is, it consists of a molecular sieve. The molecular sieve removes residual water to a level below the dew point of usually -100°C. The molecular sieve is preferably sized to remove carbon dioxide (CO2) to 100 ppb (0.1 ppm) of time-averaged breakthrough, with a peak concentration of 1 ppm or less. Carbon dioxide (CO2) is discharged from the molecular sieve exponentially over time.

[0110] One or more temperature sensors 77a may be provided in each of the first primary adsorption bed 15-1 and the second primary adsorption bed 15-2. Each temperature sensor can output a temperature signal to the electronic control unit 5 to facilitate the control of the regeneration process. The one or more temperature sensors 77a may be disposed inside any of the at least one adsorption layer. In the embodiment shown in FIG. 3A, the first temperature sensor 77A is disposed within the first adsorption layer 73 to measure the operating temperature of the process gas. The first temperature sensor 77A is a thermocouple in this embodiment. The implementation of the low-energy regeneration cycle is facilitated by measuring the operating temperature of the first adsorption layer 73. The first temperature sensor 77A can be disposed at a distance from the bottom of the first adsorption layer 73, for example, about 100 mm above the bottom of the alumina layer. The first temperature sensor 77A is preferably inserted radially from the side wall of the container 14-1, for example, at about 300 mm from the side wall. The first temperature sensor 77A is provided to enable in-bed measurement of the operating temperature of the first primary adsorption bed 15-1. Alternatively, or in addition to this, a temperature sensor may be provided at the top of the first primary adsorption bed 15-1 not only after the primary regenerator 25 but also to measure the temperature of the regeneration gas entering the adsorbent. This helps to determine the amount of heat loss between the heater and the adsorption bed. In the embodiment shown in FIG. 3B, the second temperature sensor 77B is provided at the interface between the first adsorption layer 73 and the second adsorption layer 74. In this embodiment, the second temperature sensor 77B is inserted radially from the side wall of the container 14-1, for example, at about 300 mm from the side wall. The second temperature sensor 77B is a thermocouple in this embodiment. The second temperature sensor 77B can be used to determine the amount of heat used to remove carbon dioxide (CO2) and the amount of heat remaining for desorbing water (H2O) from the activated alumina. The third temperature sensor 77C is provided in the second adsorption layer 74. In the illustrated arrangement, the third temperature sensor 77C is provided at the top of the second adsorption layer 74.

[0111] Each of the first primary absorption tower 12 and the second primary absorption tower 13 can optionally include at least one of at least one carbon dioxide (CO2) sensor 77D and at least one water (moisture) H2O sensor 77D. At least one of the carbon dioxide (CO2) sensor and the water (H2O) sensor 77D may be provided in the first adsorption layer 73. Alternatively or additionally, at least one of the carbon dioxide (CO2) sensor and the water (H2O) sensor 77D may be provided in the second adsorption layer 74. During use, the sensor 77D can monitor the content of at least one of water (H2O) and carbon dioxide (CO2) in the process gas in the first primary adsorption bed 15-1. One or more sensors 77D can be arranged in the second adsorption layer 74 below the top of the second adsorption layer 74, for example 100 mm below the top of the second adsorption layer. One or more sensors 77D can be configured to monitor carbon dioxide (CO2) in the second adsorption layer 74, for example, to determine how close carbon dioxide (CO2) is to breaking through the first primary adsorption bed 15-1 before the actual breakthrough occurs. One of the sensors 77D takes a sample of the process gas beside the side wall to check whether carbon dioxide (CO2) is flowing down the side of the container, and the other is arranged at a position spaced from the side wall, for example, within 300 mm of the side wall, to measure the bulk process gas. In the first adsorption layer 73, a similar set of sensors 77D can be provided so as to be able to monitor at least one of water (H2O) and carbon dioxide (CO2) traveling through the first adsorption layer 73, for example, located 100 mm below the top surface of the first adsorption layer 73. Alternatively or additionally, at least one of the carbon dioxide (CO2) sensor 77D and at least one water (moisture) H2O sensor 77D may be provided at the interface between the first adsorption layer 73 and the second adsorption layer 74. In this embodiment, the configuration of the sensor 77D is at least substantially the same in the first primary absorption tower 12 and the second primary absorption tower 13. It will be understood that the configuration of the sensor 77D may be different in the first primary absorption tower 12 and the second primary absorption tower 13.

[0112] Each of the first primary absorption tower 12 and the second primary absorption tower 13 has dimensions adapted to a supply time of 6 hours, and then regeneration is performed to remove adsorbed water (H2O) and carbon dioxide (CO2). The first primary absorption tower 12 and the second primary absorption tower 13 can be dimensioned according to different supply times, which may be longer or shorter than 6 hours. It will be understood that supply times less than 6 hours or greater than 6 hours are possible. Regeneration is achieved by opening and closing the primary inlet control valve 20-n of the primary inlet valve system 16 and the primary outlet control valve 23-n of the primary outlet valve system 19. As described herein, the first primary absorption bed 12 and the second primary absorption bed 13 are subjected to a plurality of operating steps. In this embodiment, the operating steps include supply, depressurization, heating, cooling, and repressurization. The heating process is performed to regenerate the first primary absorption bed 15-1. These processes are carried out by the first primary absorption bed 12 and the second primary absorption bed 13. To enable continuous operation of the gas treatment device 1, the first primary absorption bed 12 and the second primary absorption bed 13 operate in different cycles. In particular, while one of the first primary absorption bed 12 and the second primary absorption bed 13 is operating in the supply process, the other of the first primary absorption bed 12 and the second primary absorption bed 13 is regenerated. The different operating cycles of the first primary absorption bed 12 and the second primary absorption bed 13 are referred to herein as the first operating mode and the second operating mode.

[0113] The gas treatment device 1 is operated in the first operating mode and the second operating mode. The gas treatment device 1 is circulated between the first operating mode and the second operating mode. One of the first primary absorption bed 15-1 and the second primary absorption bed 15-2 is configured to process the process gas while the other of the first primary absorption bed 15-1 and the second primary absorption bed 15-2 is regenerated.

[0114] When operating in the first operating mode, the first primary adsorption bed 15-1 operates in the supply process, and untreated (supply) process gas is supplied from the primary process gas inlet 10. The first primary adsorption bed 15-1 discharges the treated process gas to the primary process gas outlet 11. In the first operating mode, the second primary adsorption bed 15-2 is connected to the secondary process gas outlet 31 and receives the process gas treated by the secondary treatment unit 3. The process gas from the secondary treatment unit 3 is supplied to the primary treatment unit 2 to regenerate the second primary absorption tower 15-2. The process gas supplied from the secondary treatment unit 3 can optionally be heated by the primary regeneration heater 25.

[0115] When operating in the second operating mode, the second primary adsorption bed 15-2 operates in the supply process, and untreated (supply) process gas is supplied from the primary process gas inlet 10. The second primary adsorption bed 15-2 discharges the treated process gas to the primary process gas outlet 11. In the second operating mode, the first primary adsorption bed 15-1 is connected to the secondary process gas outlet 31 and receives the process gas treated by the secondary treatment unit 3. The process gas from the secondary treatment unit 3 is supplied to the primary treatment unit 2 to regenerate the first primary absorption tower 15-1. The process gas supplied from the secondary treatment unit 3 can optionally be heated by the primary regeneration heater 25.

[0116] To achieve the circulation process by the first primary absorption tower 12 and the second primary absorption tower 13, the total time of all other operating steps is preferably the same as or less than the supply time for treating the process gas. In this embodiment, the following operating times are defined for each operating step: Supply: 360 minutes Decompression: 30 minutes Heating: 40 minutes Cooling: 40 minutes Re-pressurization: 30 minutes The above operating time is merely an example. It will be understood that different operating times may be applied for one or more operating processes. For example, different operating times can be implemented for the first primary absorption tower 12 and the second primary absorption tower 13 having different capacities.

[0117] Next, different operating steps will be described for the first primary absorption bed 12. It will be understood that similar operating steps are carried out by the second primary absorption bed 13.

[0118] During the supply step, the process gas passes upward through the first primary absorption bed 15-1 to remove unwanted contaminants. The treated process gas is subsequently sent to a downstream process unit. In the first operating mode, the supply step is carried out by the first primary absorption bed 15-1. In the second operating mode, the supply step is carried out by the second primary absorption bed 15-2.

[0119] In the configuration of the gas treatment apparatus 1 shown in FIG. 5, the second primary absorption tower 13 performs a supply step for treating the process gas. The flow of the process gas in this step is shown by a thick solid line in FIG. 5. The gas treatment apparatus 1 is configured to control the flow of the process gas by controlling the primary inlet control valve 20-n and the primary outlet control valve 23-n. In the arrangement shown in FIG. 5, the second primary inlet control valve 20-2 and the second primary outlet control valve 23-2 are open, and the fourth primary inlet control valve 20-4, the sixth primary inlet control valve 20-6, and the fourth primary outlet control valve 23-4 are closed. As described in this specification, the fifth primary outlet control valve 23-5 can be selectively opened to supply the treated process gas to the first primary absorption tower 12 to repressurize the first primary absorption tower 12. The primary process gas inlet 10 is connected to the second primary absorption tower 13. In particular, the primary inlet valve system 16 is configured to supply the untreated (feed) process gas to the second primary absorption tower 13. The second primary absorption tower 13 is arranged to be in fluid communication with the primary process gas inlet 10. In use, the untreated (feed) process gas is supplied from the primary process gas inlet 10 and passes through the second primary absorption bed 15-2 to remove water (H2O) and carbon dioxide (CO2). The treated process gas is discharged from the second primary absorption tower 13 to the primary process gas outlet 11. The second primary absorption tower 13 is arranged to be in fluid communication with the primary process gas outlet 11.

[0120] The primary outlet valve system 19 can be selectively configured to connect the second primary absorption tower 13 to the primary process gas outlet 11. In FIG. 5, the flow of the processed process gas from the second primary absorption tower 13 to the first primary absorption tower 12 is shown by a thick dashed line. The supply of the processed process gas to the first primary absorption tower 12 can be at least partially performed, for example, to repressurize the first primary adsorption vessel 14-1 (e.g., following the regeneration of the first primary adsorption bed 15-1). The first primary absorption tower 12 is arranged to be in fluid communication with the second primary absorption tower 13. The primary inlet valve system 16 is configured to close the inlet of the second primary absorption tower 13. The primary outlet valve system 19 opens the fifth primary outlet control valve 23-5, enabling the third branch 24-3 to function as a repressurization conduit. A portion of the processed process gas discharged from the second primary absorption tower 13 is guided into the first primary absorption tower 12. The processed process gas at least partially repressurizes the first primary adsorption vessel 14-1. The fifth primary outlet control valve 23-5 can be configured to control the ratio of the processed process gas discharged from the first primary absorption tower 12 to each of the primary process gas outlet 11 and the second primary absorption tower 12. The fifth primary outlet control valve 23-5 may be a variable flow control valve or a proportional control valve for controlling the supply of the processed process gas. The supply of the processed process gas to the first primary absorption tower 12 can be controlled independently of the operation of the second primary absorption tower 13 for processing the process gas.

[0121] Alternatively, or in addition, the first primary adsorption vessel 14-1 may be at least partially repressurized using the regeneration gas from the secondary treatment unit 3. The outlet of the first primary absorption tower 12 can be closed and the regeneration gas from the secondary treatment unit 3 can be at least partially supplied to repressurize the first primary adsorption vessel 14-1. In the present embodiment, the outlet of the first primary absorption tower 13 can be closed by closing the first primary inlet control valve 20-1, the third primary inlet control valve 20-3, and the fifth primary inlet control valve 20-5. Other valve structures can also be used to close the outlet of the first primary absorption tower 12. Alternatively, or in addition, the primary compressor 52 can supply untreated (feed) process gas to repressurize the first primary adsorption vessel 34-1.

[0122] A carbon dioxide (CO₂) analyzer 78 monitors the carbon dioxide (CO₂) concentration at the primary process gas outlet 11. The carbon dioxide (CO₂) analyzer 78 is configured to detect whether the carbon dioxide (CO₂) content of the processed process gas is greater than a predetermined carbon dioxide (CO₂) threshold. The preferred carbon dioxide (CO₂) threshold in this embodiment is defined as 1 ppm to prevent freezing of downstream equipment. The carbon dioxide (CO₂) analyzer 78 may optionally be configured to generate an alarm when the detected carbon dioxide (CO₂) is 0.2 ppm and / or 0.5 ppm. Standard air separation unit (ASU) CO₂ analyzers are typically calibrated to operate in the ppm range, and the detectable lower limit is close to 0.2 ppm. The carbon dioxide (CO₂) analyzer 78 may optionally be configured to measure carbon dioxide (CO₂) with an oxygen O₂ sample in which the carbon dioxide (CO₂) is concentrated to a level that is more easily detectable by a ppm analyzer. In this embodiment, the carbon dioxide (CO₂) analyzer 78 is a ppb analyzer for accurately measuring the target concentration. The carbon dioxide (CO₂) analyzer 78 may optionally be provided in a temperature-controlled cabinet to reduce variations due to changes in ambient temperature. The nitrogen (N₂) zero gas for the carbon dioxide (CO₂) analyzer 78 should contain carbon dioxide (CO₂) as close to zero as possible. A similar carbon dioxide (CO₂) analyzer 79 can be used to monitor the carbon dioxide (CO₂) concentration at the secondary process gas outlet 31.

[0123] A water (H₂O) analyzer may optionally be provided at the primary process gas outlet 11. However, when carbon dioxide (CO₂) has been removed, the processed process gas is generally too dry, and dew point measurement is meaningless. Therefore, there is no need to prepare a water (H₂O) analyzer.

[0124] In the modification, the supply process is continued until a breakthrough of carbon dioxide (CO2) is detected. However, accurate monitoring is preferred to avoid supplying water (H2O) to the second adsorption layer 74 (made of molecular sieve) before the CO2 breaks through. This can avoid the need to remove water (H2O) from the second adsorption layer 74, which can be proven to be difficult.

[0125] The primary treatment unit 2 shifts from the second operating mode to the first operating mode. The first primary absorption tower 12 performs a supply step for treating the process gas, and the untreated (supply) process gas is supplied to the first primary adsorption bed 15-1. The flow of the process gas in this step is shown by a thick dashed line in FIG. 6. The gas treatment device 1 is configured to control the primary inlet control valve 20-n and the primary outlet control valve 23-n to control the flow of the process gas. In the arrangement shown in FIG. 6, the first primary inlet control valve 20-1 and the first primary outlet control valve 23-1 are open, and the third primary inlet control valve 20-3, the fifth primary inlet control valve 20-5, and the third primary outlet control valve 23-3 are closed. As described herein, the fifth primary outlet control valve 23-5 can be opened to selectively supply the treated process gas to the second primary absorption tower 13. As shown in FIG. 6, the primary process gas inlet 10 is connected to the first primary absorption tower 12. The primary inlet valve system 16 is configured to supply the untreated (supply) process gas to the first primary absorption tower 12. The first primary absorption tower 12 is arranged to be in fluid communication with the primary process gas inlet 10. In use, the untreated (supply) process gas is supplied from the primary process gas inlet 10 and is treated at the first primary adsorption bed 15-1 to remove water (H2O) and carbon dioxide (CO2). The treated process gas is discharged from the first primary absorption tower 12 to the primary process gas outlet 11.

[0126] While the first primary adsorption bed 15-1 is being activated to process the process gas, the second primary adsorption bed 15-2 is regenerated. The second primary absorption tower 13 is first depressurized in a depressurization step, preferably to atmospheric pressure. The flow of the process gas in this step is shown by thick solid lines in FIG. 6. In this embodiment, the depressurization is performed over 30 minutes with the gas vented to the atmosphere. The third primary inlet control valve 20-3 and the fourth primary inlet control valve 20-4 are controlled to connect the second primary absorption tower 13 to the primary process gas vent 22. Since the second primary adsorption bed 15-2 preferentially adsorbs a small amount of N2 released during the depressurization step, the vented gas may have slightly less O2 compared to air. The vented gas may be captured by another system provided in the gas treatment device 1 and stored or utilized.

[0127] As shown in FIG. 7, the second primary adsorption bed 15-2 is subsequently regenerated in the regeneration step. The flow of the process gas in this step is shown by the thick solid line in FIG. 7. The gas treatment apparatus 1 is configured to control the flow of the process gas by controlling the primary inlet control valve 20-n and the primary outlet control valve 23-n. In the arrangement shown in FIG. 7, the sixth primary inlet control valve 20-6 and the fourth primary outlet control valve 23-4 are opened, and the second primary inlet control valve 20-2 and the fourth primary inlet control valve 20-4, as well as the second primary outlet control valve 23-2 and the fifth primary outlet control valve 23-5 are closed. The regeneration gas is supplied from the secondary treatment unit 3 to the second primary adsorption bed 15-2. The regeneration gas in this embodiment is the treated process gas. As described in this specification, the treated process gas consists of air treated to remove water (H2O) and carbon dioxide (CO2). The third primary outlet control valve 23-3 and the fourth primary outlet control valve 23-4 are configured to be arranged so as to put the regeneration gas supply conduit 4 in fluid communication with the second primary absorption tower 13. The second primary absorption tower 13 is in fluid communication with the primary process gas vent 22. The regeneration gas is the process gas treated in the secondary treatment unit 3. The regeneration gas substantially does not contain carbon dioxide (CO2) and water (H2O). The regeneration gas is passed through the primary regenerator 25 and heated to a predetermined target temperature. In this embodiment, the target temperature is 230° C., but this is set according to the specific design of the system and may vary depending on the design of the system. The heating of the regeneration gas is performed in the heating step. The heated regeneration gas flows through the depressurized first primary adsorption bed 15-1, desorbing water (H2O) and carbon dioxide (CO2) from the second primary adsorption bed 15-2 and vented through the primary process gas vent 22. The primary process gas vent 22 is preferably arranged distally from the inlets of the primary compressor 52 and the secondary compressor 53. The reason is that it is not desirable for carbon dioxide (CO2) to be concentrated in the exiting regeneration gas and returned to the gas treatment apparatus 1. Instead, the vented gas may be captured by another system provided in the gas treatment apparatus 1 and stored or utilized.As shown in FIG. 7, the gas treatment apparatus 1 is configured such that while the second primary absorption tower 13 is being regenerated, the first primary absorption tower 12 is operable to process untreated (feed) process gas supplied to the primary process gas inlet 10. The treated process gas from the first primary absorption tower 12 is discharged from the first primary absorption tower 12 to the primary process gas outlet 11.

[0128] The temperature at the outlet of the primary regenerator heater 25 is monitored and the electrical heat input is varied to maintain a target temperature of 230°C. Temperature measurements of the heater shell are taken to ensure that local overheating does not occur. The flow rate of the treated process gas from the secondary treatment unit 3 is monitored and the power to the primary regenerator heater 25 can be reduced or suppressed if the flow rate falls below a lower flow rate threshold.

[0129] In the present embodiment, the regeneration of the first primary absorption bed 15-1 and the second primary absorption bed 15-2 is performed in the downstream direction because the concentration of water (H2O) in the regeneration gas increases due to heating. The water (H2O) can be condensed by cooling at the outlet vessel head. By regenerating in the downstream direction, this condensed water is pushed out towards the primary process gas vent 22. In the case of upward flow, the condensed water may return and fall onto the adsorbent, causing problems of material degradation due to contact with liquid water. By using downstream regeneration, these problems may be reduced or improved.

[0130] After about 40 minutes, the primary regenerator heater 25 is turned off. However, the regeneration gas continues to be supplied to the second primary absorption bed 15-2 through the primary regenerator heater 25. Thereby, the residual heat in the primary regenerator heater 25 and the piping can be pushed into the first primary absorption tower 12. After the primary regenerator heater 25 has cooled, the supply of the regeneration gas continues to push down the heat through the second primary absorption bed 15-2 and continues to remove water (H2O) and carbon dioxide (CO2). Approximately 260 minutes after the switch of the primary regenerator heater 25 is turned off, the supply of the regeneration gas from the secondary treatment unit 3 is stopped. This is a signal indicating the end of the cooling step.

[0131] The regeneration of each of the first primary adsorption bed 15-1 and the second primary adsorption bed 15-2 can be performed independently of the operation of the other of the first primary adsorption bed 15-1 and the second primary adsorption bed 15-2. In at least certain embodiments, the regeneration of the first primary adsorption bed 15-1 can be carried out while the second primary adsorption bed 15-2 is operating to process the (untreated) process gas supplied from the primary process gas inlet 10. Similarly, the regeneration of the second primary adsorption bed 15-2 can be performed while the first primary adsorption bed 15-1 is operating to process the (untreated) process gas supplied from the primary process gas inlet 10.

[0132] As shown in FIG. 8, the second primary adsorption container 14-2 is repressurized in the repressurization step. The flow of the process gas in this step is shown by a thick solid line in FIG. 8. The gas treatment apparatus 1 is configured to control the flow of the process gas by controlling the primary inlet control valve 20-n and the primary outlet control valve 23-n. In the arrangement shown in FIG. 8, the first primary inlet control valve 20-1, and the first primary outlet control valve 23-1 and the fifth primary outlet control valve 23-5 are open. The second primary inlet control valve 20-2, the third primary inlet control valve 20-3, the fourth primary inlet control valve 20-4, the fifth primary inlet control valve 20-5, and the sixth primary inlet control valve 20-6, and the second primary outlet control valve 23-2, the third primary outlet control valve 23-3, and the fourth primary outlet control valve 23-4 are closed. The repressurization of the second primary adsorption container 14-2 can be performed, for example, over about 30 minutes. The repressurization in the present embodiment includes supplying a part of the treated process gas discharged from the first primary absorption tower 12 to the second primary absorption tower 13. In particular, it is a part of the treated process gas discharged from the first primary adsorption container 14-1 to the second primary adsorption container 14-2. The fifth primary outlet control valve 23-5 is opened to supply a part of the treated process gas from the first primary adsorption container 14-1 to the second primary adsorption container 14-2. The fifth primary outlet control valve 23-5 can be configured to control the ratio of the treated process gas discharged from the first primary absorption tower 12 to each of the primary process gas outlet 11 and the second primary absorption tower 12. The fifth primary outlet control valve 23-5 may be a variable flow rate control valve or a proportional control valve for controlling the supply of the treated process gas. Instead of this, a flow restrictor can also be provided to control the supply of the treated process gas. In the present embodiment, the first primary adsorption container 14-1 is repressurized from the top while flowing downward. In a modified example, the repressurization can also be performed from the bottom in the upward flow direction.

[0133] Alternatively, or in addition, the second primary adsorption vessel 14-2 may be at least partially repressurized using the regeneration gas from the secondary treatment unit 3. The outlet of the second primary absorption tower 13 may be closed and the regeneration gas from the secondary treatment unit 3 may be at least partially supplied to repressurize the second primary adsorption vessel 14-2. Alternatively, or in addition, the primary compressor 52 may supply untreated (feed) process gas to repressurize the second primary adsorption vessel 34-2. In the present embodiment, the outlet of the second primary absorption tower 13 can be closed by closing the second primary inlet control valve 20-2, the fourth primary inlet control valve 20-4, and the sixth primary inlet control valve 20-6. Other valve structures may also be used to close the outlet of the second primary absorption tower 13. Alternatively, or in addition, the primary compressor 52 may supply untreated (feed) process gas to repressurize the second primary adsorption vessel 34-2.

[0134] After the pressure in the container 14-1 becomes at least substantially equal to the pressure in the primary process gas inlet 10 supplied from the primary compressor 52, the primary processing unit 2 can change from the first operating mode to the second operating mode. The first primary absorption tower 12 and the second primary absorption tower 13 are switched so that the process gas is processed in the second primary absorption tower 13. The first primary absorption tower 12 can then be regenerated. In this embodiment, the supplied first primary absorption tower 12 undergoes regeneration starting from reduced pressure. The supplied second primary adsorption bed 15-2 is substantially in pressure equilibrium with the process gas supplied to the primary process gas inlet 10. When resetting the primary inlet valve system 16 to supply process gas from the primary compressor 52 when the pressures are not in equilibrium, the process gas may flow in suddenly. Due to this sudden change, the adsorbent may "hit" the air. As a result, abrasion and dust generation occur, the pressure loss increases, and the performance of the absorption tower deteriorates. The control device can confirm that the differential pressure between the two beds is sufficiently small before opening the primary inlet valve system 16. This differential pressure check is performed with respect to the supply inlet ends of the first primary adsorption container 14-1 and the second primary adsorption container 14-2. The reason is that the difference is the largest at this part.

[0135] The primary inlet control valve 20-n in this embodiment is a three-lever valve, which cannot be opened when the differential pressure is large. This can physically prevent the valve from opening when there is still a large differential pressure between the supplied process gas and the first primary adsorption bed 15-1 to be repressurized. An additional bypass valve may be provided to pressurize the first primary adsorption bed 15-1 at startup. Other types of valves can be used for the primary inlet control valve 20-n.

[0136] The second primary adsorption bed 15-2 is equalized on the process gas supply side. There is a pressure drop on the first primary adsorption bed 15-1 during supply due to the gas flow passing through the first primary adsorption bed 15-1, but the pressure drop on the second primary adsorption bed 15-2 is substantially zero during recompression. Therefore, the product (output) side pressures of the first primary adsorption bed 15-1 and the second primary adsorption bed 15-2 at the end of recompression are equal, but the supply (input) side pressures are not equal. When the pressure drop on the second primary adsorption bed 15-2 during supply is too large (for example, >200 mbar), the supply inlet pressure becomes higher than the pressure of the recompression bed. This means that the pressure loss on the primary inlet control valve 20-n on the supply side of the second primary adsorption bed 15-2 is too large. As a result, there is a possibility that the three-way valve cannot be opened. The pressure drop on the adsorption bed is maintained below the differential pressure threshold value that defines the upper limit at which the three-way valve is opened. Manually opening the bypass valve around the three-way valve on the supply side to reduce the differential pressure so that the three-way valve can be opened would be possible during operation.

[0137] The closing of the valve of the first primary adsorption bed 15-1 during supply is not started until it is determined that the valve of the second primary adsorption bed 15-2 during supply is fully open. This is to prevent the continuous flow through the process from stopping from the primary compressor 52.

[0138] The total time for heating and cooling during the above-described regeneration step is preferably specified as 5 hours, but the heating time may be changed during operation. The cooling time can be changed by an appropriate amount so that the total regeneration time becomes 5 hours. The heating time is preferably specified so as to achieve a peak temperature of 70 °C with the first temperature sensor 77A in the floor during the regeneration step. The heating time is calculated based on the amounts of water (H2O) and carbon dioxide (CO2) entering the container 14-1 during the supply step and a feedback loop of what the peak temperature was at this location in the previous regeneration cycle(s). When the concentrations of water (H2O) and carbon dioxide (CO2) in the feed do not change significantly, a sufficient indicator of the amount of contaminants in the container 14-1 can be obtained by measuring the cumulative amount of the process gas supplied to the first primary adsorption bed 15-1 during the supply step to the first primary adsorption bed 15-1 before regeneration. The heating time can be calculated as follows: Heating time = f(previous in-bed temperature peak) × supply time × supply flow rate The f element is the output of a proportional-integral controller that monitors the past in-bed temperature peak of the container 14-1 and targets a set value of 70 °C.

[0139] Figure 9 shows the first plot 100 of the simulated temperature inside the first primary adsorption bed 15-1 during regeneration. The first plot 105 represents the temperature at the top of the first primary adsorption bed 15-1 (after heat loss in the pipe from the heater) measured by the temperature sensor 77C. The second plot 110 represents the temperature at the interface between the first adsorption layer 73 and the second adsorption layer 74 measured by the temperature sensor 77B. The third plot 115 represents the in-bed temperature of the first adsorbent 73 (measured by the first temperature sensor 77A at a distance of 100 mm from the bottom of the first adsorption layer 73). The fourth plot 120 represents the outlet temperature from the first primary adsorption bed 15-1. As the heat pulse moves through the first primary adsorption bed 15-1, energy is consumed for the desorption of carbon dioxide (CO2) and water (H2O), causing the temperature to drop. At the outlet / bottom of the first primary adsorption bed 15-1, the maximum reached temperature is 45°C, indicating that a significant portion of the heat supplied by the primary regeneration heater 25 is used for the regeneration of the adsorbent within the first primary adsorption bed 15-1 and is hardly wasted for ventilation. It will be understood that such an operating mode of the first adsorption bed 15-1, similar to the pressure swing adsorption process, does not mean that all water (H2O) is removed from the absorption tower (activated alumina) during regeneration. However, by maintaining the same peak temperature at the in-bed temperature position for each regeneration, the long-term accumulation of water in the first primary adsorption bed 15-1 can be reduced and a steady state can be obtained.

[0140] How much water remains in the first primary adsorption bed 15-1 at the end of each cycle can be changed by varying the set value of the peak temperature inside the adsorption bed. The higher the value, the greater the energy input to the system and the less water on the first primary adsorption bed 15-1 at the end of regeneration. The lower the value, the less the energy input and the more water on the bed.

[0141] As described in this specification, the recompression of the first primary adsorption bed 15-1 uses a part of the treated process gas discharged from the second primary adsorption bed 15-2 in its supply step, as shown in FIG. 5, which means that there is a temporary decrease in the flow rate through the primary process gas outlet 11 to the cold end of the process. The gas flow rate for recompressing the first primary adsorption bed 15-1 is highest at the start of recompression when the flow through the fifth primary outlet control valve 23-5 is blocked. As an example, a flow rate of about 1700 Nm 3 / h corresponds to about 2.4% of the process gas flow rate. Over the duration of the recompression step (about 30 minutes in this embodiment), the cumulative loss of the treated process gas is about 1.8%, which corresponds to a loss of 0.15% when measured compared to the amount of treated process gas generated during the entire cycle. Not only is the treated process gas consumed, but the recompression step also significantly raises the temperature of the second adsorption layer 74 (which can consist of molecular sieves). This is because N2 and O2 are adsorbed during the recompression step and heat is released to the bed. In parallel, it is also possible to adopt a step of supplying both the first adsorption bed 15-1 and the second adsorption bed 15-2 for a certain period of time to mitigate the temperature change of the combined treated process gas. As an example, the parallel supply step may be performed for 40 minutes to reduce the temperature change. The potential disadvantage of adding the parallel step is that the time available for heating and cooling may be shortened, requiring a higher regeneration flow rate and thus a larger secondary treatment unit 3. The gas treatment apparatus 1 according to this embodiment operates without passing through the parallel supply step of the first adsorption bed 15-1 and the second adsorption bed 15-2.

[0142] In the recompression step, nitrogen N2 in the recompression gas is preferentially adsorbed over oxygen O2. This means that in the subsequent supply step, the treated process gas contains a higher concentration of oxygen O2 than air. The oxygen O2 concentration and nitrogen N2 concentration settle over a period of time, for example about 20 minutes, while the molecular sieve is cooled after recompression. During this time, additional nitrogen N2 in the supply gas is adsorbed, and the oxygen O2 concentration in the treated process gas becomes slightly higher than that in the untreated process gas.

[0143] Each time the adsorbent is thermally regenerated, a portion of the activated alumina in the first adsorption layer 73 changes from the basic state of aluminum oxide to aluminum hydroxide. The chemical formula is as follows:

[0144]

Chemical formula

[0145] This reaction is favorable for the formation of aluminum hydroxide at low temperatures but is kinetically limited. The reaction rate can only be evaluated during the regeneration step when the temperature of the first primary adsorption bed 15-1 is significantly higher than the supply temperature of the process gas. Since aluminum hydroxide has zero ability to adsorb water, the performance deteriorates. Although it is possible to convert aluminum hydroxide back to aluminum oxide, this requires a temperature in the range of 400°C to 600°C, which is much higher than the temperature practically achievable in situ. Therefore, the conversion to aluminum hydroxide should be considered irreversible, and if the process is operated long enough, all of the activated alumina will ultimately be lost in this way.

[0146] The design of the first adsorption bed 15-1 and the second adsorption bed 15-2 depends on putting a significant amount of additional activated alumina into the first adsorption layer 73 compared to the amount required to account for the "aging" of the material over time. This can reduce the number of times the material needs to be exchanged, but it is expected that the adsorbent will need to be reloaded at some point during the life of the process.

[0147] Since it is thermally driven, by operating at a lower regeneration temperature for the alumina layer in accordance with the cycle design of the regeneration process, the deterioration rate of the activated alumina can be reduced. If it is operated at a higher regeneration temperature or with a longer heating time, the aging rate of the adsorbent will increase, so it should be avoided except when dealing with excessive CO2 breakthrough.

[0148] The second adsorption layer 74 made of molecular sieve is only used for the removal of carbon dioxide (CO2) and generally does not deteriorate over time as long as it is not exposed to water. Nitrogen (N2), oxygen (O2), and carbon dioxide (CO2) hardly damage the structure of the molecular sieve even in the presence of heat. The performance of the molecular sieve may deteriorate when a significant amount of moisture from the first adsorption layer 73 begins to penetrate. Since water (H2O) is preferentially adsorbed, the CO2 adsorption capacity of the molecular sieve decreases, the amount that can be removed from the feed gas decreases, and the time until breakthrough is shortened.

[0149] Thermal regeneration removes water from the molecular sieve of the second adsorption layer 74 during each regeneration cycle. However, when the amount of water is significant, using a low-energy cycle means that multiple regeneration cycles are required to remove all the water. Operating with an extended heating time is also effective in this regard and can ultimately fully restore the carbon dioxide removal capacity of the molecular sieve.

[0150] The gas treatment device 1 can be configured to enable continuous operation. During the supply step, the untreated (feed) process gas is supplied to one of the first adsorption bed 15-1 and the second adsorption bed 15-2 for 6 hours, and the other of the first adsorption bed 15-1 and the second adsorption bed 15-2 is regenerated. Every 6 hours, the first adsorption bed 15-1 and the second adsorption bed 15-2 are swapped, and the process starts again.

[0151] The gas treatment device 1 can be configured to operate intermittently. At least one of the primary treatment unit 2 and the secondary treatment unit 3 can operate intermittently. In at least a specific embodiment, the primary treatment unit 2 or the secondary treatment unit 3 can operate independently of the other. The secondary treatment unit 3 can continue to operate to supply a regeneration gas for regenerating at least one of the first primary adsorption bed 15-1 and the second primary adsorption bed 15-2, for example, regardless of whether the other adsorption beds are undergoing a supply step, a recompression step, or a decompression step, when the primary treatment unit 2 is inoperable (e.g., offline). The adsorption process can be stopped when one of the first adsorption bed 15-1 and the second adsorption bed 15-2 is at the operating pressure. Mass transfer can occur through the adsorption bed by the diffusion of water (H2O) and carbon dioxide (CO2). When the adsorption bed is held under pressure, the spread of water (H2O) and carbon dioxide (CO2) may be relatively small. The total supply time achievable after being returned to the conduit may be close to the 6-hour design time described herein. Thus, assuming that the supply-side primary adsorption bed 15-1 is sealed when the liquid air energy storage plant stops and is returned to the conduit without hitting the adsorbent, intermittent operation can be performed without having a negligible impact on the performance of the supply process.

[0152] In the regeneration step, it is preferable to continue the heating and cooling steps once started. If the regeneration step is postponed, the heat pulse in the first primary adsorption bed 15-1 will disperse, which may cause problems, especially as water (H2O) desorbs and moves to a re-adsorbable location. For example, water (H2O) can be adsorbed onto the second adsorption layer 74. Due to the high diffusion rate at low pressure and high temperature and the low capacity of the adsorbent, there is little to prevent the movement of components around the bed. Keeping activated alumina in contact with water at a high temperature for a long time is also considered to contribute to the thermal hydrolysis aging of the adsorbent.

[0153] By holding the first primary adsorption bed 15-1 during regeneration, there is a possibility that thermal energy is dissipated due to heat loss from the wall of the container 14-1. Then, when regeneration resumes, the low-temperature regeneration gas may not be able to achieve the desired removal of carbon dioxide (CO2) and water (H2O). In that case, the supplyable time when the container 14-1 is supplied again is significantly shortened.

[0154] Since the regeneration gas of the primary treatment unit 2 is supplied from the independent secondary treatment unit 3, it is not necessary to stop the regeneration step even if the primary compressor 52 stops. Therefore, even when the main process is stopped, the regeneration step can be continuously executed. It is possible to sufficiently complete the regeneration of one of the first adsorption bed 15-1 and the second adsorption bed 15-2 before the other of the first adsorption bed 15-1 and the second adsorption bed 15-2 in supply finishes the supply process. The regenerated bed should preferably be repressurized as soon as possible. The repressurized bed is operable, which facilitates the replacement between the first adsorption bed 15-1 and the second adsorption bed 15-2, for example, when the diffusion of carbon dioxide (CO2) is detected. Preferably, the first adsorption bed 15-1 and the second adsorption bed 15-2 are not replaced until the activity of the first primary adsorption bed 15-1 and the second primary adsorption bed 15-2 in supply accumulates 6 hours of operation or until a CO2 breakthrough occurs. In this way, the active primary adsorption bed 15-1 is fully utilized before entering the regeneration cycle.

[0155] The regeneration gas for regenerating the first adsorption bed 15-1 and the second adsorption bed 15-2 of the primary treatment unit 2 is supplied from a secondary treatment unit 3 that generates a dried treated process gas substantially free of carbon dioxide CO2. In this embodiment, the regeneration gas for regenerating the first adsorption bed 15-1 and the second adsorption bed 15-2 is exclusively supplied from the secondary treatment unit 3. In a modified example, a part of the regeneration gas can also be supplied from an alternative source. As shown in FIG. 1, an untreated (supply) process gas is supplied to the secondary treatment unit 3 from a secondary compressor 53. The secondary compressor 53 can be composed of a two-stage compression package unit equipped with an intercooler and an aftercooler that use cooling water and ambient air. The secondary compressor 53 compresses ambient air to 3.5 barg at the outlet of the aftercooler 80. Since the regeneration gas flow rate required by the primary treatment unit 2 is not continuous, the secondary compressor 53 is configured to be reduced to substantially zero flow rate in order to save power. The change in the regeneration gas flow rate is not only because the primary treatment unit 2 operates intermittently, but also because the regeneration gas is supplied only intermittently, for example, for 300 minutes out of 360 minutes. The remaining time (60 minutes in this example) is spent on depressurization and repressurization of the first adsorption bed 15-1 and the second adsorption bed 15-2 of the primary treatment unit 2.

[0156] The secondary treatment unit 3 consists of a secondary cooler 81 for receiving the untreated (supply) process gas supplied from the secondary compressor 53 to the secondary process gas inlet 30. The secondary cooler 81 may be substantially equivalent to the cooler 55 of the primary treatment unit 2 described above. Two or more secondary coolers 81 can also be provided to cool the required amount of process gas. The plurality of secondary coolers 81 can operate in parallel. Similar to the primary cooler 55, the secondary cooler 81 may consist of a bypass valve (not shown) that can be operated to preemptively cut off the refrigerant loop to prevent freezing of the water in the refrigerant heat exchanger. The secondary cooler 81 can have the following exemplary operating parameters: Pressure: 3 barg Temperature: 26.3 °C Dew point: 5 °C CO2: 470 ppm As described herein, the secondary treatment unit 3 shares many of the characteristics of the primary treatment unit 2. Next, the main differences between the secondary treatment unit 3 and the primary treatment unit 2 will be described.

[0157] The primary treatment unit 2 requires a supply of regeneration gas for 5 hours, while the secondary treatment unit 3 has a maximum supply time of 6 hours until regeneration of one of the first primary adsorption beds 15-1 and the second primary adsorption beds 15-2 is required, and is preferably designed to be consistent with the primary treatment unit 2. The preferred cycle time of the secondary treatment unit 3 is as follows: Supply: 360 minutes Pressure reduction: 15 minutes Heating: 60 minutes Cooling: 270 minutes Re-pressurization: 15 minutes The above operating times are merely examples. It will be understood that different operating times may be applied for one or more operating processes.

[0158] Since the pressure change within the secondary treatment unit 3 is lower, preferably only between 3 barg and atmospheric pressure, the time for pressure reduction and re-pressurization is shorter than that of the primary treatment unit 2. In the secondary treatment unit 3, even when the dew point is the same, the amount of moisture in the inflowing gas is larger at this supply pressure, so the heating time becomes longer.

[0159] The secondary treatment unit 3 is regenerated periodically. In particular, the first secondary absorption tower 32 and the second secondary absorption tower 33 are regenerated periodically. The regeneration of the secondary treatment unit 3 can be carried out independently of the operation of the primary treatment unit 2. For example, the secondary treatment unit 3 can be regenerated while the primary treatment unit 2 is online (i.e., operating) or offline (not operating). One or both of the first secondary absorption beds 35-1 and the second secondary absorption beds 35-2 of the secondary treatment unit 3 can be regenerated before the primary treatment unit 2 goes online or after it goes offline, i.e., before or after the primary treatment unit 2 is configured to process the (untreated) process gas supplied from the primary gas inlet 10. Alternatively, or in addition, the regeneration of the secondary treatment unit 3 can also be carried out in parallel with the operation of the primary treatment unit 2. One or both of the first secondary absorption beds 35-1 and the second secondary absorption beds 35-2 of the secondary treatment unit 3 can be regenerated while the primary treatment unit 2 is online, i.e., while one of the first primary absorption beds 15-1 and the second primary absorption beds 15-2 of the primary treatment unit 2 is operating to process the (untreated) process gas supplied from the primary gas inlet 10. At least one of the first secondary absorption beds 35-1 and the second secondary absorption beds 35-2 of the secondary treatment unit 3 can be regenerated when the primary treatment unit 2 is operating in at least one of the first operating mode and the second operating mode described herein. As described herein, while regenerating one of the first secondary absorption tower 32 and the second secondary absorption tower 33, the other of the first secondary absorption tower 32 and the second secondary absorption tower 33 can be operated to process the untreated (supply) process gas supplied from the secondary process gas inlet 30. At least in certain embodiments, this allows the supply of the treated process gas from the secondary treatment unit 3 to continue while one of the first primary absorption beds 15-1 and the second primary absorption beds 15-2 is being regenerated.

[0160] The regeneration of the secondary treatment unit 3 can be executed according to the operating mode of the primary treatment unit 2. Among the first secondary adsorption bed 35-1 and the second secondary adsorption bed 35-2, the first one can be regenerated when the primary treatment unit 2 is operating in the first operating mode, and the second one among the first secondary adsorption bed 35-1 and the second secondary adsorption bed 35-2 can be regenerated when the primary treatment unit 2 is operating in the second operating mode. Alternatively, the regeneration of the secondary treatment unit 3 can also be performed independently of the operating mode of the primary treatment unit 2. The first secondary adsorption bed 35-1 and the second secondary adsorption bed 35-2 can be regenerated regardless of whether the primary treatment unit 2 is operating in the first operating mode or the second operating mode. Thereby, the secondary treatment unit 3 can operate independently of the primary treatment unit 2. In at least a specific embodiment, this improves the flexibility for controlling the operation of the gas treatment device 1.

[0161] The regeneration of the secondary treatment unit 3 uses, in the same manner as the primary treatment unit 2, a part of the processed process gas from one of the first secondary adsorption beds 35-1 and the second secondary adsorption beds 35-2 for supply. Preferably, even when the flow to the primary treatment unit 2 is not necessary for regeneration, once the regeneration is started, it is not stopped. For this purpose, it is necessary to supply the processed process gas to either one of the first secondary adsorption beds 35-1 and the second secondary adsorption beds 35-2, but only supply an amount sufficient to supply the regeneration gas to the secondary treatment unit 3. A variable speed compressor may be provided in the secondary compressor 53. The variable speed compressor can be controlled to change the flow rate of the untreated (supply) process gas, for example, according to whether the regeneration is being executed for at least one of the secondary treatment unit 3 and the primary treatment unit 2. The regenerated secondary adsorption containers 34-1, 34-2 are repressurized after cooling. At least one of the first secondary adsorption container 34-1 and the second secondary adsorption container 34-2 may be at least partially repressurized by supplying a part of the regeneration gas from the other of the first secondary adsorption container 34-1 and the second secondary adsorption container 34-2. Instead of or in addition to this, the processed process gas from the primary treatment unit 2 may be supplied to repressurize at least one of the first secondary adsorption container 34-1 and the second secondary adsorption container 34-2. Instead of or in addition to this, the secondary compressor 53 may supply the untreated (supply) process gas to repressurize at least one of the first secondary adsorption container 34-1 and the second secondary adsorption container 34-2. Thereby, the regeneration of one of the first primary adsorption bed 15-1 and the second primary adsorption bed 15-2 of the primary treatment unit 2 becomes possible. Next, the operation of the secondary treatment unit 3 for regenerating the first primary adsorption bed 15-1 and the second primary adsorption bed 15-2 will be described with reference to FIGS. 10 to 15.

[0162] As shown in FIG. 10, the second secondary absorption tower 33 performs a supply step for treating the untreated (supply) process gas supplied from the secondary process gas inlet 30. The flow of the process gas in this step is shown by a thick dashed line in FIG. 10. The gas treatment apparatus 1 is configured to control the secondary inlet control valve 40-n and the secondary outlet control valve 43-n to control the flow of the process gas. In the arrangement shown in FIG. 10, the second secondary inlet control valve 40-2 and the second secondary outlet control valve 43-2 are open, and the fourth secondary inlet control valve 40-4, the sixth secondary inlet control valve 40-6, and the fourth secondary outlet control valve 43-4 are closed. The secondary inlet valve system 36 is configured to supply the untreated (supply) process gas from the secondary process gas inlet 30 to the second secondary absorption tower 33. In use, the untreated (supply) process gas is supplied from the secondary process gas inlet 30 and passes through the second secondary absorption bed 35-2 to remove water (H2O) and carbon dioxide (CO2). The treated process gas is discharged from the second secondary absorption tower 33 to the secondary process gas outlet 31. The second secondary absorption tower 33 is arranged to be in fluid communication with the secondary process gas outlet 31. Various configurations of the secondary inlet control valve 40-n are conceivable. For example, the fifth secondary inlet control valve 40-5 and the sixth secondary inlet control valve 40-6 can be omitted. The third secondary inlet control valve 40-3 and the fourth secondary inlet control valve 40-4 can be configured to depressurize the first secondary absorption tower 32 and the second secondary absorption tower 33.

[0163] Each of the secondary inlet control valves 40-n has a valve flow coefficient (Cv) that represents the flow capacity in the fully open operating state with respect to the pressure drop across the valve. In the present embodiment, the secondary inlet control valves 40-n have different valve flow coefficients (Cv). The secondary inlet control valves 40-n can be configured to implement different flow capacities for different operating processes. In the present embodiment, the valve flow coefficients (Cv) of the third secondary inlet control valve 40-3 and the fourth secondary inlet control valve 40-4 are smaller than the valve flow coefficients (Cv) of the fifth secondary inlet control valve 40-5 and the sixth secondary inlet control valve 40-6. As described in this specification, the third secondary inlet control valve 40-3 and the fourth secondary inlet control valve 40-4 are opened to depressurize the corresponding first secondary adsorption vessel 34-1 and second secondary adsorption vessel 34-2, and the fifth secondary inlet control valve 40-5 and the sixth secondary inlet control valve 40-6 are opened to purge (regenerate) the corresponding first secondary adsorption bed 35-1 and second secondary adsorption bed 35-2. The smaller the valve flow coefficients (Cv) of the third secondary inlet control valve 40-3 and the fourth secondary inlet control valve 40-4, the lower the gas flow rate for depressurization is maintained. This can help avoid a high gas flow rate that could potentially cause damage to the support grids for supporting the adsorption beds 35-1, 35-2 by imposing a large downward force on the first secondary adsorption bed 35-1 and the second secondary adsorption bed 35-2. The first secondary adsorption bed 35-1 and the second secondary adsorption bed 35-2 are preferably in a state close to atmospheric pressure before starting regeneration. Otherwise, when the purge (regeneration) step valve is opened, the gas flow rate increases, so the transient gas flow rate could become very large.

[0164] Alternatively, one or more secondary inlet control valves 40-n may consist of variable control valves. The third secondary inlet control valve 40-3 and the fourth secondary inlet control valve 40-4 may each consist of a variable flow control valve operable to regulate or adjust the flow capacity. The third secondary inlet control valve 40-3 and the fourth secondary inlet control valve 40-4 may be configured to provide a first flow capacity for pressure reduction and a second flow capacity for purge (regeneration). The first flow capacity may be smaller than the second flow capacity. Alternatively, or in addition, the third secondary inlet control valve 40-3 and the fourth secondary inlet control valve 40-4 can be opened and closed pulsatingly (pulse width modulation) to regulate the flow capacity. The fifth secondary inlet control valve 40-5 and the sixth secondary inlet control valve 40-6 can be optionally omitted.

[0165] While the second secondary adsorption bed 35-2 is active for processing the process gas, the first secondary absorption tower 32 can be depressurized, preferably to atmospheric pressure, in a depressurization step. The flow of the process gas at this step is shown by a thick solid line in FIG. 10. The first secondary inlet control valve 40-1, the fourth secondary inlet control valve 40-4, the fifth secondary inlet control valve 40-5, and the sixth secondary inlet control valve 40-6 are closed, and the fifth secondary inlet control valve 40-5 is opened to arrange the first secondary absorption tower 32 in fluid communication with the secondary vent 42.

[0166] As shown by the thick solid line in FIG. 11, the second secondary absorption tower 33 executes a regeneration step of subsequently supplying a part of the processed process gas from the second secondary absorption tower 33 to the first secondary absorption tower 32 to regenerate the first secondary absorption bed 35-1. The first secondary outlet control valve 43-1 and the fourth secondary outlet control valve 43-4 are closed, and the third secondary outlet control valve 43-3 is opened to connect the first secondary absorption tower 32 to the secondary process gas outlet 31. The fifth secondary outlet control valve 43-5 is closed. The first secondary inlet control valve 40-1, the third secondary inlet control valve 40-3, the fourth secondary inlet control valve 40-4, and the sixth secondary inlet control valve 40-6 are closed, and the third secondary inlet control valve 40-3 is opened to arrange the first secondary absorption tower 32 to be in fluid communication with the secondary vent 42. A part of the processed process gas from the second secondary absorption tower 33 is supplied to the first secondary absorption tower 32 via the heater supply conduit 37. The secondary regeneration control valve 49 can be controlled to control the supply of the processed process gas for regeneration. The secondary regeneration heater 45 can be controlled to adjust the heating of the processed process gas before introducing it into the first secondary absorption tower 32 to regenerate the first secondary absorption bed 35-1. The second heater control device 46 can control the secondary regeneration heater 45, for example, according to the second operating temperature T2 measured by the second secondary temperature sensor 48. The depressurization of the first secondary absorption tower 32 and the supply of the processed process gas for regenerating the first secondary absorption tower 32 are described as being executed as separate steps. It will be understood that the depressurization and regeneration may be performed simultaneously. For example, the first secondary absorption tower 32 can be arranged to be in fluid communication with the secondary vent 42 substantially simultaneously with or after starting the supply of the regeneration gas. This control strategy can be adopted during the regeneration of other absorption towers described in this specification, for example, during the regeneration of the first primary absorption tower 12 and the second primary absorption tower 13.

[0167] After the regeneration of the first adsorption bed 35-1, the first secondary adsorption container 34-1 is repressurized. The first secondary adsorption container 34-1 can be repressurized by closing the first secondary inlet control valve 40-1, the third secondary inlet control valve 40-3, and the fifth secondary inlet control valve 40-5 while continuing to supply the processed process gas via the heater supply conduit 37. In the present embodiment, as shown in FIG. 12, the fifth secondary outlet control valve 43-5 is used to control the supply of the processed process gas from the second secondary absorption tower 33 in order to repressurize the first secondary adsorption container 34-1. The gas treatment device 1 is configured to control the secondary inlet control valve 40-n and the secondary outlet control valve 43-n to repressurize the first secondary adsorption container 34-1. The second secondary inlet control valve 40-2 and the second secondary outlet control valve 43-2 are opened. The first secondary inlet control valve 40-1, the third secondary inlet control valve 40-3, the fourth secondary inlet control valve 40-4, the fifth secondary inlet control valve 40-5, and the sixth secondary inlet control valve 40-6, as well as the first secondary outlet control valve 43-1, the third secondary outlet control valve 43-3, and the fourth secondary outlet control valve 43-4 are closed. The fifth secondary outlet control valve 43-5 is opened to supply a part of the processed process gas from the second secondary absorption tower 33 to the first secondary absorption tower 32, as shown by the thick solid line in FIG. 12. The fifth secondary outlet control valve 43-5 can be selectively opened to supply the processed process gas to the first secondary absorption tower 32 to repressurize the first secondary absorption tower 32. The repressurization of the first secondary adsorption container 34-2 can be performed, for example, over about 30 minutes. The repressurization in the present embodiment includes supplying a part of the treated process gas discharged from the second secondary absorption tower 32 to the first secondary absorption tower 33. The fifth secondary outlet control valve 43-5 may be a variable flow control valve or a proportional control valve for controlling the supply of the processed process gas. Alternatively, a flow restrictor can be provided to control the supply of the processed process gas. In the present embodiment, the first secondary adsorption container 34-1 is repressurized from the top while flowing downward. In a modified example, the repressurization can also be performed from the bottom in the upward flow direction.

[0168] As shown in FIG. 13, the first secondary absorption tower 32 executes a supply step for treating the process gas in which the untreated (supply) process gas is supplied to the first secondary absorption bed 35-1. The flow of the process gas in this step is shown by a thick dashed line in FIG. 13. The gas treatment apparatus 1 is configured to control the secondary inlet control valve 40-n and the secondary outlet control valve 43-n to control the flow of the process gas. In the arrangement shown in FIG. 13, the first secondary inlet control valve 40-1 and the first secondary outlet control valve 43-1 are open, and the third secondary inlet control valve 40-3, the fifth secondary inlet control valve 40-5, and the third secondary outlet control valve 43-3 are closed. The secondary process gas inlet 30 is configured to supply the untreated (supply) process gas to the first secondary absorption tower 32. In use, the untreated (supply) process gas is supplied from the secondary process gas inlet 30 and is treated by the first secondary absorption bed 35-1 to remove water (H2O) and carbon dioxide (CO2). The treated process gas is discharged from the first secondary absorption tower 32 to the secondary process gas outlet 31.

[0169] While the first secondary absorption bed 35-1 is active in treating the process gas, the second secondary absorption tower 33 can be depressurized, preferably to atmospheric pressure, in a depressurization step. The flow of the process gas in this step is shown by a thick solid line in FIG. 13. The second secondary inlet control valve 40-2, the third secondary inlet control valve 40-3, the fifth secondary inlet control valve 40-5, and the sixth secondary inlet control valve 40-6 are closed, and the sixth secondary inlet control valve 40-6 is opened to arrange the second secondary absorption tower 33 in fluid communication with the secondary vent 42, as shown by the thick solid line in FIG. 13.

[0170] As shown by the thick solid line in FIG. 14, the second secondary absorption tower 33 executes a regeneration step of subsequently supplying a part of the processed process gas from the first secondary absorption tower 32 to the second secondary absorption tower 33 to regenerate the second secondary absorption bed 35-2. The second secondary outlet control valve 43-2 and the third secondary outlet control valve 43-3 are closed, and the fourth secondary outlet control valve 43-4 is opened to connect the second secondary absorption tower 33 to the secondary process gas outlet 31. The fifth secondary outlet control valve 43-5 is closed. The second secondary inlet control valve 40-2, the third secondary inlet control valve 40-3, the fourth secondary inlet control valve 40-4, and the fifth secondary inlet control valve 40-5 are closed, and the fourth secondary inlet control valve 40-4 is opened to arrange the second secondary absorption tower 33 to be in fluid communication with the secondary vent 42. A part of the processed process gas from the first secondary absorption tower 32 is supplied to the second secondary absorption tower 33 via the heater supply conduit 37. The secondary regeneration control valve 49 can be controlled to control the supply of the processed process gas for regeneration. The secondary regeneration heater 45 can be controlled to adjust the heating of the processed process gas before introducing it into the second secondary absorption tower 33 to regenerate the second secondary absorption bed 35-2. The second heater control device 46 can control the secondary regeneration heater 45, for example, according to the first operating temperature T1 measured by the first secondary temperature sensor 47. The depressurization of the second secondary absorption tower 33 and the supply of the processed process gas for regenerating the second secondary absorption tower 33 are described as being executed as separate steps. It will be understood that the depressurization and regeneration may be performed simultaneously. For example, the second secondary absorption tower 33 can be arranged to be in fluid communication with the secondary vent 42 substantially simultaneously with or after starting the supply of the regeneration gas. This control strategy can be adopted during the regeneration of other absorption towers described in this specification, for example, during the regeneration of the first primary absorption tower 12 and the second primary absorption tower 13.

[0171] After the regeneration of the second adsorption bed 35-1, the second secondary adsorption vessel 34-2 is repressurized. The second secondary adsorption vessel 34-2 can be repressurized by closing the second secondary inlet control valve 40-2, the fourth secondary inlet control valve 40-4, and the sixth secondary inlet control valve 40-6 while continuing to supply the processed process gas through the heater supply conduit 37. In the present embodiment, as shown in FIG. 15, the fifth secondary outlet control valve 43-5 is used to control the supply of the processed process gas from the first secondary absorption tower 32 in order to repressurize the second secondary adsorption vessel 34-2. The gas treatment apparatus 1 is configured to control the secondary inlet control valve 40-n and the secondary outlet control valve 43-n to repressurize the secondary adsorption vessel 34-2. The first secondary inlet control valve 40-1 and the first secondary outlet control valve 43-1 are opened. The second secondary inlet control valve 40-2, the third secondary inlet control valve 40-3, the fourth secondary inlet control valve 40-4, the fifth secondary inlet control valve 40-5, and the sixth secondary inlet control valve 40-6, and the second secondary outlet control valve 43-2, the third secondary outlet control valve 43-3, and the fourth secondary outlet control valve 43-4 are closed. The fifth secondary outlet control valve 43-5 is opened to supply a part of the processed process gas from the first secondary absorption tower 32 to the second secondary absorption tower 33 as shown by the thick solid line in FIG. 15. The fifth secondary outlet control valve 43-5 can be selectively opened to supply the processed process gas to the second secondary absorption tower 33. The repressurization of the second secondary adsorption vessel 34-2 can be performed, for example, over about 30 minutes. The repressurization in the present embodiment includes supplying a part of the processed process gas discharged from the first secondary absorption tower 32 to the second secondary absorption tower 33. The fifth secondary outlet control valve 43-5 may be a variable flow rate control valve or a proportional control valve for controlling the supply of the processed process gas. Instead of this, a flow restrictor can also be provided to control the supply of the processed process gas. In the present embodiment, the first secondary adsorption vessel 34-1 is repressurized from the top while flowing downward. In a modified example, the repressurization can also be performed from the bottom in the upward flow direction.

[0172] As shown in FIGS. 10 and 12, the regeneration of the first secondary adsorption bed 35-1 and the second secondary adsorption bed 35-2 in this embodiment is performed in the downstream direction. Water (H2O) can be condensed by cooling at the outlet vessel head. By regenerating in the downstream direction, this condensed water is pushed toward the secondary process gas vent 22.

[0173] Regarding carbon dioxide (CO2) removal, the design of the secondary treatment unit 3 is consistent with that of the primary treatment unit 2 in the sizing of the adsorbent to obtain a preferred peak breakthrough of 1 ppm and a time average of less than 100 ppb. Alternatively, the primary treatment unit 2 may require that the carbon dioxide (CO2) partial pressure at the outlet be at most 1.6 Pa or less and less than 0.16 Pa on average. That is, the amount of CO2 in the regeneration gas also needs to be less than these values on a partial pressure basis. This corresponds to a maximum CO2 partial pressure of about 5 Pa and an average of about 0.5 Pa at the outlet from the secondary treatment unit 3 before the pressure drops close to atmospheric pressure. When the operating pressure is 3 barg, this corresponds to a maximum allowable breakthrough of 12 ppm and a time average of 1.2 ppm, that is, a breakthrough allowable amount more than one order of magnitude larger than that for which the secondary treatment unit 3 is designed.

[0174] Prior to the first startup, the primary adsorption vessels 14-1, 14-2 and the secondary adsorption vessels 34-1, 34-2 are filled with the required amount of adsorbent. This needs to be done in a dry state because moisture in the ambient air can adsorb to the material and liquid moisture can damage the structure of the material.

[0175] The secondary treatment unit 3 starts earlier than the primary treatment unit 2. The secondary compressor 53 and the secondary cooler 81 are turned on to raise the supply of the process gas to the operating pressure and reduce the temperature of the refrigerant in the secondary cooler 81. The compressed process gas is subsequently bypassed around the supply inlet valve of one of the selected first secondary adsorption bed 35-1 and the second secondary adsorption bed 35-2 and slowly raised to a predetermined pressure. Once this is achieved, the inlet supply valve is opened. The processed process gas from one of the selected first secondary adsorption bed 35-1 and the second secondary adsorption bed 35-2 is used following the regeneration of the other of the first secondary adsorption bed 35-1 and the second secondary adsorption bed 35-2. It is recommended to extend the heating time by 6 hours and then cool it. The regenerated secondary adsorption beds 35-1, 35-2 are subsequently repressurized, switched for supply, and the other of the first secondary adsorption bed 35-1 and the second secondary adsorption bed 35-2 is regenerated. Here too, the heating time is set to 6 hours and it is recommended to cool it afterwards. This process needs to be repeated by switching the beds until the gas coming from the product sides of both the first secondary adsorption bed 35-1 and the second secondary adsorption bed 35-2 is moderately dried and free of carbon dioxide (CO2). Since the regeneration air from the first bed may contain water and carbon dioxide (CO2) to be discharged from the system, it may take more than one cycle to achieve this.

[0176] The adsorbent may be shipped from the vendor containing up to 1.5 weight% (wt%) of moisture and may also take in moisture in the atmosphere during filling. Therefore, lengthening the heating time is to ensure that the adsorbent is as dry as possible.

[0177] When the secondary treatment unit 3 is in the normal playback mode, the processed process gas from the secondary treatment unit 3 can be supplied as a regeneration gas for regenerating both the first primary adsorption bed 15-1 and the second primary adsorption bed 15-2 of the primary treatment unit 2. Also in this case, after the 6-hour heating step, both the first primary adsorption bed 15-1 and the second primary adsorption bed 15-2 are cooled. Since the gas sent to regenerate the first primary adsorption bed 15-1 and the second primary adsorption bed 15-2 is clean, one regeneration is sufficient.

[0178] The primary compressor 52 starts together with the primary cooler 55. The process gas bypasses one of the supply inlet valves and is sent to one of the first primary adsorption bed 15-1 and the second primary adsorption bed 15-1 and recompressed. The processed process gas is then taken out from the first adsorption container 14-1, and the dryness and the carbon dioxide (CO2) content can be confirmed. If this is too high, the first primary adsorption bed 15-1 can be depressurized and regenerated again using the regeneration gas supplied from the secondary treatment unit 3. This can be repeated until the required carbon dioxide (CO2) and water (H2O) are satisfied. Once this is done for one of the first primary adsorption bed 15-1 and the second primary adsorption bed 15-2, this process can be repeated for the other of the first primary adsorption bed 15-1 and the second primary adsorption bed 15-2.

[0179] It will be understood that various changes and modifications can be made to the present invention without departing from the scope of the present application.

Claims

1. A gas treatment device for treating a process gas, the gas treatment device comprising a primary treatment unit and a secondary treatment unit, the primary treatment unit and the secondary treatment unit being configured to treat the process gas, The primary treatment unit includes a primary process gas inlet for receiving the process gas, a first primary absorption tower and a second primary absorption tower for treating the process gas, and at least one primary process gas outlet for discharging the process gas treated from the first primary absorption tower and the second primary absorption tower, The secondary treatment unit includes a secondary process gas inlet for receiving the process gas, at least one secondary absorption tower for treating the process gas, and at least one secondary process gas outlet for discharging the treated process gas from the at least one secondary absorption tower to the primary treatment unit, The primary treatment unit is selectively configurable in a first operating mode and a second operating mode, When operating in the first operating mode, the primary process gas inlet is connected to the first primary absorption tower to supply the process gas to the first primary absorption tower for treatment, and the second primary absorption tower is connected to the at least one secondary process gas outlet to receive the process gas treated from the secondary treatment unit to regenerate the second primary absorption tower, When operating in the second operating mode, the primary process gas inlet is connected to the second primary absorption tower to supply the process gas to the second primary absorption tower for treatment, and the first primary absorption tower is connected to the at least one secondary process gas outlet to receive the process gas treated from the secondary treatment unit to regenerate the first primary absorption tower. A gas treatment device for treating a process gas.

2. The gas treatment device according to claim 1, wherein when operating in the first operating mode, after the regeneration of the second primary absorption tower, a part of the process gas treated from the first primary absorption tower is supplied for repressurizing the second primary absorption tower.

3. When operating in the second operating mode, after the regeneration of the first primary absorption tower, a part of the processed process gas from the second primary absorption tower is supplied for repressurizing the first primary absorption tower, the gas treatment device according to claim 1 or 2.

4. When operating in the first operating mode, before the regeneration of the second primary absorption tower, the second primary absorption tower is depressurized, the gas treatment device according to any one of claims 1 to 3.

5. When operating in the second operating mode, before the regeneration of the first primary absorption tower, the first primary absorption tower is depressurized, the gas treatment device according to any one of claims 1 to 4.

6. Comprising a primary regeneration heater for heating the processed process gas from the secondary treatment unit before introducing it into the primary treatment unit, the gas treatment device according to any one of claims 1 to 5.

7. The gas treatment device is selectively configurable to regenerate the secondary treatment unit, and the regeneration of the secondary treatment unit is carried out independently of the operating mode of the primary treatment unit, the gas treatment device according to any one of claims 1 to 6.

8. The at least one secondary absorption tower consists of a first secondary absorption tower and a second secondary absorption tower for treating the process gas, the gas treatment device according to any one of claims 1 to 7.

9. In use, one of the first secondary absorption tower and the second secondary absorption tower is operatively selected to treat the process gas, and the other of the first secondary absorption tower and the second secondary absorption tower is regenerated, the gas treatment device according to claim 8.

10. The regeneration includes outputting a part of the processed process gas from the selected one of the first secondary absorption tower and the second secondary absorption tower to regenerate the other of the first secondary absorption tower and the second secondary absorption tower, the gas treatment device according to claim 9.

11. Comprising a secondary regeneration heater for heating the processed process gas to regenerate the other of the first secondary absorption tower and the second secondary absorption tower, the gas treatment device according to claim 10.

12. A primary compressor for compressing the process gas supplied to the primary process gas inlet of the primary treatment unit, and The gas treatment device according to any one of claims 1 to 11, comprising at least one of secondary compressors for compressing the process gas supplied to the secondary process gas inlet of the secondary treatment unit.

13. Comprising a primary outlet valve system configured to selectively connect one of the first primary absorption tower and the second primary absorption tower to the at least one primary process gas outlet. The primary outlet valve system is configured to selectively connect the secondary treatment unit to one of the first primary absorption tower and the second primary absorption tower for performing regeneration. The gas treatment device according to any one of claims 1 to 12.

14. The gas treatment device according to any one of claims 1 to 13, comprising a secondary outlet valve system configured to selectively connect one of the first secondary absorption tower and the second secondary absorption tower to at least one secondary process gas outlet.

15. Comprising a primary inlet valve system configured to selectively connect the primary process gas inlet to one of the first primary absorption tower and the second primary absorption tower. The primary inlet valve system is configured to selectively vent process gas from one of the first primary absorption tower and the second primary absorption tower to depressurize the first primary absorption tower and the second primary absorption tower. The gas treatment device according to any one of claims 1 to 14.

16. Comprising a secondary inlet valve system configured to selectively connect the secondary process gas inlet to one of the first secondary absorption tower and the second secondary absorption tower. The secondary inlet valve system is configured to selectively vent process gas from one of the first secondary absorption tower and the second secondary absorption tower to depressurize the first primary absorption tower and the second primary absorption tower. The gas treatment device according to any one of claims 1 to 15.

17. The primary processing unit and the secondary processing unit are configured to remove carbon dioxide (CO ２ ) and water (H ２ O) from the process gas. The gas treatment apparatus according to any one of claims 1 to 16.

18. The gas treatment device according to any one of claims 1 to 17, wherein the process gas is air.

19. A method for controlling a gas treatment device for treating a process gas, wherein the gas treatment device is A primary process gas inlet for receiving the process gas, a first primary absorption tower and a second primary absorption tower for processing the process gas, and at least one primary process gas outlet for discharging the process gas processed from the first primary absorption tower and the second primary absorption tower, comprising a primary processing unit; A secondary process gas inlet for receiving the process gas, at least one secondary absorption tower for processing the process gas, and at least one secondary process gas outlet for discharging the processed process gas from the at least one secondary absorption tower to the primary processing unit, comprising a secondary processing unit; Comprising; The method includes the step of selectively operating the primary processing unit in a first operating mode and a second operating mode, When operating in the first operating mode, the primary process gas inlet is connected to the first primary absorption tower to supply the unprocessed process gas to the first primary absorption tower for processing, and the second primary absorption tower is connected to the at least one secondary process gas outlet to receive the process gas processed from the secondary processing unit to regenerate the second primary absorption tower, When operating in the second operating mode, the primary process gas inlet is connected to the second primary absorption tower to supply the process gas to the second primary absorption tower for processing, and the first primary absorption tower is connected to the at least one secondary process gas outlet to receive the process gas processed from the secondary processing unit to regenerate the first primary absorption tower, a method for controlling a gas treatment device for processing a process gas.

20. A gas treatment device for processing a process gas, the gas treatment device comprising a primary processing unit and a secondary processing unit, the primary processing unit and the secondary processing unit being configured to process the process gas, The primary processing unit includes a primary process gas inlet for receiving the process gas, a first primary absorption tower and a second primary absorption tower for processing the process gas, and at least one primary process gas outlet for discharging the process gas processed from the first primary absorption tower and the second primary absorption tower, The secondary treatment unit includes a secondary process gas inlet for receiving the process gas, at least one secondary absorption tower for treating the process gas, and at least one secondary process gas outlet for discharging the treated process gas from the at least one secondary absorption tower to the primary treatment unit. In use, the primary process gas inlet is connected to the first primary absorption tower to supply the process gas to the first primary absorption tower for treatment in a first operating mode, and the primary process gas inlet is connected to the second primary absorption tower to supply the process gas to the second primary absorption tower for treatment in a second operating mode. In use, the secondary treatment unit is selectively connected to at least one of the first primary absorption tower and the second primary absorption tower, and is a gas treatment device for supplying a treated process gas to at least one of the first primary absorption tower and the second primary absorption tower to regenerate it.

21. A method for controlling a gas treatment device for treating a process gas, the gas treatment device comprising: a primary treatment unit comprising a primary process gas inlet for receiving the process gas, a first primary absorption tower and a second primary absorption tower for treating the process gas, and at least one primary process gas outlet for discharging the treated process gas from the first primary absorption tower and the second primary absorption tower; a secondary treatment unit comprising a secondary process gas inlet for receiving the process gas, at least one secondary absorption tower for treating the process gas, and at least one secondary process gas outlet for discharging the treated process gas from the at least one secondary absorption tower to the primary treatment unit; The method comprises: connecting the primary process gas inlet to the first primary absorption tower to supply the untreated process gas to the first primary absorption tower for treatment in a first operating mode; connecting the primary process gas inlet to the second primary absorption tower to supply the process gas to the second primary absorption tower for treatment in a second operating mode; Connecting the secondary treatment unit to at least one of the first primary absorption tower and the second primary absorption tower to supply a process gas that has been treated to regenerate at least one of the first primary absorption tower and the second primary absorption tower; A method of controlling a gas treatment apparatus for treating a process gas, comprising:

22. An electronic control unit configured to control a gas treatment apparatus so as to execute the method according to claim 19 or 21.

23. A liquid air energy storage plant comprising the gas treatment apparatus according to any one of claims 1 to 18 or 20.

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