Method and apparatus for drying process gas

Abstract

The present disclosure relates to an apparatus (10) for drying a process gas. The apparatus (10) includes a main adsorber (11) having an inlet (14) for receiving process gas from a compressor and an outlet (16) for discharging the process gas. The first auxiliary adsorber (12) has an adsorber for adsorbing moisture. The second auxiliary adsorber (13) also has an adsorber for adsorbing moisture. The apparatus (10) is configured to fluidly connect an outlet of the main adsorber (16) to at least one of the first auxiliary adsorber (12, 13) and the second auxiliary adsorber (12, 13). At least one of the first and second auxiliary adsorber (12, 13) is operable to adsorb moisture to dry the process gas discharged from the main adsorber. The present disclosure also relates to a method, a controller, and a non-transitory computer-readable medium for drying a process gas.

Description

Technical Field

[0001] The present disclosure relates to a method and apparatus for drying process gas. More particularly, the present invention relates to, but is not limited to, a method and apparatus for adsorbing moisture to reduce the dew point of process gas. Instead of, or in addition to, this, the method and apparatus may adsorb contaminants such as carbon dioxide (CO2) from the process gas.

Background Art

[0002] In certain industrial processes, it is desirable to lower the dew point of process gases such as air. This is particularly important, for example, in cryogenic processes involving cryogenic fluids. Cryogenic fluids are used, for example, in generating electrical energy from waste heat. The higher the dew point, the higher the frequency of defrosting of the plant, which can be costly to the operation of the plant. It is advantageous to configure the adsorber to produce a product stream with a much lower dew point (e.g., less than -70°C or less than -100°C). By lowering the dew point, the need for defrosting can be reduced. This can extend the operation of the plant between defrosts of the plant. There may also be other opportunities to reduce at least one of the operating costs and capital costs of the adsorber.

[0003] In at least certain embodiments, the present invention seeks to address or overcome limitations associated with prior art systems.

Summary of the Invention

Problems to be Solved by the Invention

[0004] Aspects of the present invention relate to the apparatus, method, and non-transitory computer-readable media recited in the appended claims.

Means for Solving the Problems

[0005] According to a further aspect of the present invention, an apparatus for drying process gas is provided, which apparatus A main adsorption unit having an inlet for receiving process gas from the compressor and an outlet for discharging process gas, The apparatus comprises a first auxiliary adsorption section containing an adsorbent for adsorbing moisture, and a second auxiliary adsorption section containing an adsorbent for adsorbing moisture, wherein the outlet of the main adsorption section is configured to be fluidly connected to at least one of the first auxiliary adsorption section and the second auxiliary adsorption section, and at least one of the first auxiliary adsorption section and the second auxiliary adsorption section is operable to adsorb moisture in order to dry the process gas discharged from the main adsorption section.

[0006] The process gas supplied from the compressor has a relatively high moisture content and is also called wet process gas. During use, the main adsorption unit dries the process gas supplied from the compressor. During use, at least one of the first auxiliary adsorption unit and the second auxiliary adsorption unit adsorbs moisture from the process gas discharged from the main adsorption unit. In this way, at least one of the first auxiliary adsorption unit and the second auxiliary adsorption unit performs auxiliary drying of the process gas. The process gas received from the compressor is also called wet process gas. The process gas discharged from at least one of the first auxiliary adsorption unit and the second auxiliary adsorption unit is also called dry process gas. Additional drying is performed to lower the dew point of the process gas. In at least certain embodiments, the apparatus can dry the process gas to lower the dew point to the following: -70°C (-94°F), -80°C (-112°F), -90°C (-130°F), or -100°C (-148°F).

[0007] Both the first and second auxiliary adsorption units can be operated to dry the process gas discharged from the main adsorption unit. For example, both the first and second auxiliary adsorption units can be connected in parallel or in series.

[0008] Alternatively, the apparatus may be configured to fluidly connect one of the first auxiliary adsorption section and the second auxiliary adsorption section to the outlet of the main adsorption section. The selected one of the first and second auxiliary adsorption sections can dry the process gas and discharge the dried process gas.

[0009] In at least certain embodiments, one of the first auxiliary adsorption section and the second auxiliary adsorption section is configured to dry the process gas, and the other of the first and second auxiliary adsorption sections is configured to regenerate. The apparatus can be reconfigured to alternately use the corresponding first and second auxiliary adsorption sections between drying and regeneration.

[0010] One or more adsorbents in the first auxiliary adsorption section may be molecular sieve adsorbents having a porous structure. The molecular sieve adsorbents may be crystalline aluminosilicate or zeolite. Multiple adsorbents may be arranged within the first auxiliary adsorption section. Multiple layers of adsorbents can be formed.

[0011] One or more adsorbents in the second auxiliary adsorption section may be molecular sieve adsorbents having a porous structure. The molecular sieve adsorbents may be crystalline aluminosilicate or zeolite. Each adsorbent may be arranged in a layer within the second auxiliary adsorption section. Multiple adsorbents can be arranged in the second auxiliary adsorption section. Multiple layers can be formed by the adsorbents.

[0012] The apparatus may be configured to supply a regenerating gas to the other of the first and second auxiliary adsorption sections in order to regenerate the adsorbent located in the other of the first and second auxiliary adsorption sections.

[0013] The apparatus may be configured to establish a flow of process gas through the first auxiliary adsorption section and the second auxiliary adsorption section in a first direction. Regenerated gas can be supplied through the first and second auxiliary adsorption sections in the first direction (i.e., the same direction as the process gas). Alternatively, the regenerated gas may be supplied through the first and second auxiliary adsorption sections in a second direction. The second direction may be the opposite direction to the first direction.

[0014] The regenerated gas may include at least a portion of the drying process gas discharged from one of the first auxiliary adsorption unit and the second auxiliary adsorption unit, which is selected from the first.

[0015] The apparatus may include a transfer conduit for supplying a drying process gas to a selected one of a first auxiliary adsorption unit and a second auxiliary adsorption unit. A control valve may be provided to control the supply of the drying process gas between the first and second auxiliary adsorption units. Alternatively, or in addition to this, a flow limiter may be provided in the transfer conduit. The flow limiter may be a variable flow limiter.

[0016] The regeneration gas flow rate may be constant or variable. The regeneration gas flow rate can be increased or decreased over time. For example, substantially all of the drying process gas can be supplied for a predetermined period. Afterward, the drying process gas flow rate can be reduced.

[0017] The apparatus may include a heater for heating the regenerated gas. The heater may be configured to heat the drying process gas supplied from a selected one of the first and second auxiliary adsorption units before introducing it into the other of the first and second auxiliary adsorption units.

[0018] During the regeneration process, the heater is activated for a first period and then deactivated for a second period. Regeneration gas may be supplied throughout the regeneration process. The second period may be longer than the first period.

[0019] The apparatus may be configured to regenerate the adsorbents located in the other of the first and second auxiliary adsorption sections by introducing regenerating gas into the main adsorption section after it has been supplied to the other of the first and second auxiliary adsorption sections. The apparatus may also be provided with a return conduit for introducing the regenerating gas into the main adsorption section.

[0020] The apparatus may be equipped with a cooler for cooling the regenerated gas before introducing it into the main adsorption section. The cooler may consist of an appropriate cooling device.

[0021] The apparatus may also include a compressor for compressing the regenerated gas before introducing it into the main adsorption section.

[0022] This device can be configured to change one of the first and second auxiliary adsorption units so that the other of the first and second auxiliary adsorption units operates to dry the process gas and discharge the dried process gas.

[0023] This device can also be configured to change which of the first and second auxiliary adsorption sections is regenerated. The regenerated gas can be supplied to the other of the first and second auxiliary adsorption sections, regenerating the adsorbents placed within it.

[0024] A further aspect of the present invention provides a method for drying process gas, the method being: The steps include: discharging process gas from the main adsorption section, The method includes the steps of selectively supplying a process gas from a main adsorption unit to at least one of a first auxiliary adsorption unit and a second auxiliary adsorption unit, and drying the process gas by having at least one of the first auxiliary adsorption unit and the second auxiliary adsorption unit adsorb moisture.

[0025] The method may include the step of fluidly connecting one of the first auxiliary adsorption part and the second auxiliary adsorption part selected to the main adsorption part, and one of the first auxiliary adsorption part and the second auxiliary adsorption part selected dries the process gas and discharges the dried process gas.

[0026] The method may include the step of supplying a regeneration gas to the other of the first auxiliary adsorption part and the second auxiliary adsorption part to regenerate the adsorbent disposed in the other of the first auxiliary adsorption part and the second auxiliary adsorption part. The regeneration gas may include at least a part of the dried process gas discharged from one of the first auxiliary adsorption part and the second auxiliary adsorption part selected.

[0027] This method may include the step of heating the regeneration gas. This method may include the step of supplying the heated regeneration gas in a first period and supplying the unheated regeneration gas in a second period during the regeneration process. The second period may be longer than the first period.

[0028] This method may include the step of introducing the regeneration gas into the main adsorption part after being supplied to the other of the first auxiliary adsorption part and the second auxiliary adsorption part to regenerate the adsorbent disposed in the other of the first auxiliary adsorption part and the second auxiliary adsorption part.

[0029] This method may include the step of cooling the regeneration gas prior to introducing it into the main adsorption part.

[0030] This method may include the step of compressing the regeneration gas prior to introducing it into the main adsorption part.

[0031] The method may include the step of changing one of the first auxiliary adsorption part and the second auxiliary adsorption part selected, whereby the other of the first auxiliary adsorption part and the second auxiliary adsorption part operates to dry the process gas and discharge the dried process gas.

[0032] Furthermore, this method may include a step of changing which of the first auxiliary adsorption section and the second auxiliary adsorption section is regenerated. The regenerated gas can be supplied to the other of the first and second auxiliary adsorption sections to regenerate the adsorbents located in the other of the first and second auxiliary adsorption sections.

[0033] A further aspect of the present invention provides an apparatus for drying a process gas, comprising: a first adsorption section containing an adsorbent for adsorbing moisture; and a second adsorption section containing an adsorbent for adsorbing moisture; the apparatus is configured to supply a process gas to at least one of the first and second adsorption sections, and at least one of the first and second adsorption sections is operable to adsorb moisture for drying the process gas. The apparatus may be configured to supply the process gas to a selected one of the first and second adsorption sections for drying. In at least certain embodiments, one of the first and second adsorption sections is configured to dry the process gas, and the other of the first and second adsorption sections is configured to regenerate. The apparatus may be configured to supply a regenerating gas to the other of the first and second adsorption sections for regenerating an adsorbent located in the other of the first and second adsorption sections. The regenerated gas may contain at least a portion of the drying process gas discharged from one of the selected first and second adsorption sections. The apparatus can be reconfigured to alternately use the corresponding first and second adsorption sections between drying and regeneration.

[0034] A further aspect of the present invention provides a method for drying a process gas, comprising the step of selectively supplying the process gas to at least one of a first adsorption unit and a second adsorption unit, the first adsorption unit and the second adsorption unit adsorb moisture to dry the process gas. The method may also include the step of supplying the process gas to a selected one of the first adsorption unit and the second adsorption unit, the selected one of the first adsorption unit and the second adsorption unit drying the process gas. The method may also include the step of supplying a regenerating gas to the other of the first adsorption unit and the second adsorption unit to regenerate the adsorbent located in the other of the first adsorption unit and the second adsorption unit. The regenerating gas may include at least a portion of the dried process gas discharged from the selected one of the first adsorption unit and the second adsorption unit. The method may also include alternating between drying and regeneration of the corresponding first adsorption unit and the second adsorption unit.

[0035] A further aspect of the present invention provides a non-transient computer-readable medium that stores therein a set of instructions that, when executed, cause a processor to perform the method described herein.

[0036] In a further aspect of the present invention, a control unit is provided for controlling the operation of the apparatus described herein. The control unit may consist of one or more electronic processors and memory systems. The control unit may be configured to control the operation of a control valve in order to control the supply of process gas from the main adsorption unit to at least one of a first auxiliary adsorption unit and a second auxiliary adsorption unit. The control unit may also control the operation of at least one of a heater and a cooler.

[0037] The control units or control devices described herein may preferably consist of a computing device having one or more electronic processors. The system may consist of one control unit or electronic control device, or alternatively, different functions of the control device may be embodied in or hosted in different control units or control devices. As used herein, the terms “control unit” or “control device” are understood to include both one control unit or control device and multiple control units or control devices operating collectively, providing any control function. To constitute a control unit or control device, a suitable set of instructions can be provided that, when executed, causes the control unit or computing device to implement the control techniques defined herein.

[0038] The instruction set can preferably be embedded in one or more electronic processors. Alternatively, the instruction set may be provided as software stored in one or more memories associated with the control unit so as to be executed on the computing device. The control unit or control unit can be implemented as software running on one or more processors. One or more other control units or control units can be implemented as software running on one or more processors, optionally the same one or more processors as the first control unit. Other suitable arrangements may also be used.

[0039] Within the scope of this application, the various aspects, embodiments, examples, and alternatives, in particular their individual elements, described in the preceding paragraphs, claims, and / or the following specification and drawings are expressly intended to be taken independently or in any combination. That is, all embodiments and / or elements of any embodiment can be combined in any way and / or combination, provided that such elements are not incompatible. The applicant reserves the right to modify the claims originally filed, or to file new claims accordingly, including the right to amend the claims originally filed to include elements of other claims that were not originally claimed as such, but are dependent on and / or incorporate elements of other claims. [Brief explanation of the drawing]

[0040] [Figure 1] Figure 1 is a schematic diagram showing an apparatus according to an embodiment of the present invention in the first configuration. [Figure 2] Figure 2 is a schematic diagram showing the adsorption section of the device shown in Figure 1. [Figure 3] Figure 3 is a schematic diagram showing the apparatus shown in Figure 1 in a second configuration. [Figure 4] Figure 4 is a block diagram illustrating the operation of the apparatus according to an embodiment of the present invention. [Figure 5] Figure 5 is a schematic diagram showing the electronic control unit of the device shown in Figure 1. [Modes for carrying out the invention]

[0041] Next, one or more embodiments of the present invention will be described illustratively with reference to the accompanying drawings.

[0042] Next, an apparatus 10 for drying process gas according to one aspect of the present invention will be described with reference to the attached drawings. In this embodiment, the process gas is air. The apparatus 10 is configured to dry the process gas and remove moisture in order to lower the dew point of the process gas. The apparatus 10 of this embodiment is configured to dry the process gas to a dew point of at least -70°C (minus 70°C), preferably -100°C (minus 100°C). By reducing the dew point, the need for defrosting (removal of frost) of plant equipment downstream of the apparatus 10 can be reduced.

[0043] As shown in Figure 1, the apparatus 10 consists of a main adsorption unit 11, a first adsorption unit 12, and a second auxiliary adsorption unit 13. The main adsorption unit 11 consists of an inlet port 14 connected to a supply line 15 for receiving process gas from a compressor (P), and an outlet port 16 for discharging process gas. An electronic control unit (ECU) (shown in Figure 5) is provided to control the operation of the apparatus 10. The process gas received from the compressor has a relatively high moisture content and may be called a humid process gas. In this embodiment, the main adsorption unit 11 is configured to partially dry the process gas supplied from the compressor. The process gas discharged from the main adsorption unit 11 can be called a partially dried process gas. The main adsorption unit 11 consists of one or more adsorbents for processing the process gas. The adsorbents of the main adsorption unit 11 may consist of molecular sieve adsorbents such as crystalline aluminosilicate (known as zeolite). Molecular sieve adsorbents have a porous structure suitable for adsorbing moisture from process gas. Molecular sieve adsorbents can also adsorb carbon dioxide (CO2) from process gases. A suitable molecular sieve is the 13X type adsorbent available from Zeochem®. The 13X type adsorbent is a sodium type of zeolite X with larger pore openings. Calcium X (CaX) is a calcium exchanger for the 13X type zeolite. Molecular sieve adsorbents are placed in one or more floor sections (not shown) of the main adsorption section 11 to adsorb moisture from the process gas. The main adsorption section 11 consists of a pressure vessel 17 configured to support an operating pressure exceeding atmospheric pressure. The pressure vessel 17 in this embodiment is approximately 3.6 meters in diameter and approximately 5 meters in length. The process gas discharged from the main adsorption section 11 has a time-averaged carbon dioxide (CO2) concentration of 1 ppm and a dew point of approximately -40°C (minus 40°C).

[0044] The main adsorption unit 11 is configured to dry the process gas to a target dew point of -70°C (minus 70°C). As described herein, the first auxiliary adsorption unit 12 and the second auxiliary adsorption unit 13 are configured to achieve a dew point that is -70°C (minus 70°C) or lower, and may be -100°C (minus 100°C) or lower. The first auxiliary adsorption unit 12 and the second auxiliary adsorption unit 13 are also effective in reducing the time-averaged carbon dioxide (CO2) concentration. In at least certain embodiments, the carbon dioxide (CO2) concentration in the process gas can be reduced from 1 ppm (parts per million) to 100 ppb (parts per billion). The process gas dried by at least one of the first auxiliary adsorption unit 12 and the second auxiliary adsorption unit 13 is output for use in industrial processes. The apparatus 10 is particularly suitable for drying process gas used for power generation from waste heat.

[0045] The first auxiliary adsorption section 12 and the second auxiliary adsorption section 13 are configured to perform auxiliary drying of the process gas. The first auxiliary adsorption section 12 and the second auxiliary adsorption section 13 may be called polishing adsorbents or auxiliary adsorbents, respectively. The first auxiliary adsorption section 12 and the second auxiliary adsorption section 13 have substantially the same structure as each other. The first auxiliary adsorption section 12 and the second auxiliary adsorption section 13 consist of corresponding first adsorption vessels 18 and second adsorption vessels 19. The first adsorption vessels 18 and the second adsorption vessels 19 have substantially the same diameter as the pressure vessel 17 of the main adsorption section 11. In this embodiment, the first adsorption vessels 18 and the second adsorption vessels 19 each have a diameter of approximately 3.6 meters and a length of approximately 1 meter. The first adsorption vessels 18 and the second adsorption vessels 19 can also be pressure vessels. However, in this embodiment, the first adsorption vessels 18 and the second adsorption vessels 19 are non-pressure vessels. The first adsorption container 18 and the second adsorption container 19 are configured to withstand temperature cycling. The first adsorption container 18 comprises a first process gas inlet 20A, a first process gas outlet 20B, a first regeneration gas inlet 21A, and a first regeneration gas outlet 21B. In this embodiment, the first process gas inlet 20A and the first regeneration gas outlet 21B are located at the bottom or on the bottom wall of the first adsorption container 18, and the first process gas outlet 20B and the first regeneration gas inlet 21B are located at the top or on the top wall of the first adsorption container 18. The second adsorption container 19 comprises a second process gas inlet 23A, a second process gas outlet 23B, a second regeneration gas inlet 24A, and a second regeneration gas inlet 24B. In this embodiment, the second process gas inlet 23A and the second regeneration gas outlet 24B are located at the bottom or on the bottom wall of the second adsorption container 19, and the second process gas outlet 23B and the second regeneration gas inlet 24A are located at the top or on the top wall of the second adsorption container 18.

[0046] The first auxiliary adsorption section 12 and the second auxiliary adsorption section 13 each consist of one or more adsorbents, or each adsorbent is configured to adsorb moisture present in the process gas discharged from the main adsorption section 11. One or more adsorbents can form one or more layers Ln in the corresponding first adsorption container 18 and second adsorption container 19. During use, the process gas flows through one or more adsorbents. Moisture in the process gas is adsorbed by one or more adsorbents, thereby drying the process gas. The first auxiliary adsorption section 12 and the second auxiliary adsorption section 13 undergo a periodic regeneration process to adsorb moisture.

[0047] In the regeneration process, a regeneration gas is supplied to regenerate the adsorbents in the first auxiliary adsorption section 12 and the second auxiliary adsorption section 13. As described herein, one of the first auxiliary adsorption section 12 and the second auxiliary adsorption section 13 is regenerated, while the other of the first auxiliary adsorption section 12 and the second auxiliary adsorption section 13 continues to dry the process gas from the main adsorption section 11. The regeneration gas consists of a dry gas supplied from a dedicated source. The regeneration gas may consist of air dried by, for example, a suitable dryer or individual adsorbents. In this embodiment, the regeneration gas consists of a dry process gas from one of the first auxiliary adsorption section 12 and the second auxiliary adsorption section 13.

[0048] In this embodiment, the first auxiliary adsorption section 12 and the second auxiliary adsorption section 13 each contain activated alumina (alumina desiccant) or consist of an adsorbent made of activated alumina. Because the amount of impurities that need to be removed from the process gas is very small, the amount of adsorbent required is relatively small. In practice, the required depth of the adsorbent can be smaller than the depth of the adsorbent bed located in the main adsorption section 11. A smaller depth of the adsorbent allows for a better flow rate distribution. The activated alumina forms an adsorbent bed with a depth of approximately 0.5 meters. A minimum bed depth of 1 meter would be appropriate to achieve the required flow rate distribution. The activated alumina can be operated to adsorb moisture from the process gas and dry the process gas. The activated alumina can also be operated to adsorb carbon dioxide (CO2) from the process gas, thereby performing a cleaning function. The pressure drop in the first auxiliary adsorption section 12 and the second auxiliary adsorption section 13 can be about one-fifth of the pressure drop in the main adsorption section 11, for example, about 40 mbar. Alternatively, or in addition, the adsorbents of the first auxiliary adsorption section 12 and the second auxiliary adsorption section 13 may consist of molecular sieve adsorbents. The molecular sieve adsorbents may be of the type described herein with respect to the main adsorption section 11. The molecular sieve adsorbents may require further heating to regenerate the adsorbents. In a modified example, the first auxiliary adsorption section 12 and the second auxiliary adsorption section 13 may each consist of adsorbents containing or made of crystalline aluminosilicate.

[0049] As shown in Figure 2, the first auxiliary adsorption section 12 and the second auxiliary adsorption section 13 can each consist of a first adsorption layer L-1 containing or made of activated alumina and a second adsorption layer L-2 containing or made of molecular sieve adsorbents. The first adsorption layer L-1 and the second adsorption layer L-2 can each have a depth of approximately 0.5 meters. Each adsorbent in the first adsorption layer L-1 and the second adsorption layer L-2 must be sufficient to remove the required amount of water and carbon dioxide (CO2) from the process gas. The first auxiliary adsorption section 12 and the second auxiliary adsorption section 13 can be arranged so that the process gas flows through the activated alumina and then through the molecular sieve adsorbents of the second adsorption layer L-2.

[0050] The first adsorbent layer L-1 of activated alumina is located proximal to the corresponding first process gas inlet 20A and second process gas inlet 23A in the adsorption vessels 18 and 19. The second adsorbent layer L-2 of molecular sieve adsorbent is located proximal to the corresponding first regeneration gas inlet 21A and second regeneration gas inlet 24A in the adsorption vessels 18 and 19.

[0051] In the regeneration process, a second adsorbent layer L-2, made of molecular sieve adsorbent, is exposed to a higher temperature regeneration gas, thereby accelerating regeneration. This ensures the regeneration of the entire adsorbent layer, even near the walls of the first and second adsorption vessels 18 and 19, where higher heat loss may occur. In this configuration, the second adsorbent layer L-2 of molecular sieve adsorbent is located on top of the first adsorbent layer L-1 of activated alumina. The first adsorbent layer L-1 of activated alumina can be regenerated at a lower temperature, which is achieved as a result of its distal position from the regeneration gas inlets 21A and 24A. It will be understood that different adsorbents may be used for the first auxiliary adsorption section 12 and the second auxiliary adsorption section 13.

[0052] The apparatus 10 is selectively operable to configure one of the first auxiliary adsorption section 12 and the second auxiliary adsorption section 13 to process process gas discharged from the main adsorption section 11, and to configure the other of the first auxiliary adsorption section 12 and the second auxiliary adsorption section 13 for regeneration. In the configuration shown in Figure 1, the first auxiliary adsorption section 12 is configured to dry (or purify) the process gas discharged from the main adsorption section 11, and the second auxiliary adsorption section 13 is configured for regeneration. In this configuration, the dried process gas is discharged from the first auxiliary adsorption section 12. The dried process gas is used as a regeneration gas to regenerate the other of the first auxiliary adsorption section 12 and the second auxiliary adsorption section 13. At least a portion of the dried process gas is selectively supplied from the first auxiliary adsorption section 12 to the second auxiliary adsorption section 13 to carry out regeneration. This specification describes the operation of the apparatus 10 with respect to the configuration shown in Figure 1. As shown in Figure 3, the device 10 can be reconfigured to reverse the operation of the first auxiliary adsorption unit 12 and the second auxiliary adsorption unit 13.

[0053] A transfer conduit 26 is provided to supply drying process gas from the first auxiliary adsorption unit 12 to the second auxiliary adsorption unit 13 for the regeneration of the second auxiliary adsorption unit 13. A first control valve 27 is provided to control the supply of drying process gas in the transfer conduit 26. Regeneration of activated alumina at high pressure is generally avoided because it leads to rapid hydrothermal aging of the material, but the trace amounts of water present in the second auxiliary adsorption unit 13 are not expected to cause any particular problems in this regard. A flow limiter may optionally be provided in the transfer conduit 26 to control the flow rate. A heater 28 is provided to heat the drying process gas before introducing it into the second auxiliary adsorption unit 13. The heater 28 consists of, for example, an electric heater having one or more heating elements. The heater 28 is configured to heat the drying process gas to a regeneration temperature suitable for the regeneration of the adsorbents in the second auxiliary adsorption unit 13. The rated power of the heater 28 is approximately 115 kW in this embodiment. The heater 28 is configured to heat the drying process gas to a temperature of 200°C or higher. A regeneration temperature of 200°C is sufficient to regenerate the activated alumina (and molecular sieve adsorbents) by causing the activated alumina to release the trapped water. Due to the heating time and the regeneration temperature of 200°C, the input energy is considerably greater (about 20 times) than the energy theoretically required to remove CO2 and water from the floor. In a modified configuration, heaters may be directly provided inside the first adsorption section 12 and the second adsorption section 13 to heat the adsorbents.

[0054] During the regeneration process, the heater 28 is initially activated (energized) to heat the drying process gas supplied to the second auxiliary adsorption unit 13. The drying process gas supplied to the second auxiliary adsorption unit 13 is effective in heating the adsorbent in the second adsorption container 19 to a regeneration temperature suitable for adsorbent regeneration. Subsequently, the heater 28 is deactivated (energized). The supply of the drying process gas continues for the remainder of the regeneration process to cool the adsorbent. Regeneration is performed by heating the gas for a short time, and then supplying unheated regeneration drying process gas for a longer cooling period. During the cooling period, heat is pushed out through the floor, removing moisture and trace amounts of carbon dioxide (CO2). The heater 28 may be active to perform heating for a first period during the regeneration process, for example, 1 hour, and the cooling process may continue for a second period. The second period is longer than the first period. For example, the first period may be 1 hour and the second period 5 hours. In this embodiment, the total time of the regeneration process is 6 hours. This corresponds to the operating time of the first auxiliary adsorption unit 12, which dries the process gas discharged from the main adsorption unit 11.

[0055] A return conduit 30 is provided for returning the regenerated gas to the main adsorption unit 11. The return conduit 30 is connected upstream of the inlet port 14 so that the regenerated gas is supplied to the main adsorption unit 11. A cooler 31 is provided in the return conduit 30 to cool the regenerated gas before it is introduced into the main adsorption unit 11. A blower (or compressor) 32 is provided in the return conduit 30 to increase the pressure of the regenerated gas. A valve, such as a one-way valve, may be provided in the return conduit 30 to prevent the process gas supplied to the main adsorption unit 11 from being introduced into the return conduit 30. The main adsorption unit 11 is configured to process the regenerated gas. In this embodiment, the main adsorption unit 11 operates to remove moisture from the product gas. The regenerated gas that has left the adsorption unit being regenerated is cooled by the cooler 31 before the blower 32 returns the gas flow to the inlet of the main adsorption unit 11. Therefore, the water and carbon dioxide (CO2) removed by the second adsorption unit 13 are recycled back into the system via the main adsorption unit 11 and discharged from the system. There are no pressure change processes employed by the first adsorption unit 12 and the second adsorption unit 13. No net compressed air is lost from the system.

[0056] Assuming a constant flow rate for the gas used in the heating and cooling steps, the required amount is calculated to be 1800 Nm3 / h (normal cubic meters per hour). Assuming a pressure drop of 300 mbar over the main adsorption section 11 and 100 mbar over the first and second adsorption sections 12 and 13 (including the floor for supply and regeneration, and the heater and cooler), a 2 kW blower 32 is required at 70% efficiency. Therefore, the total time-averaged power required for the apparatus 20 is relatively low, at only 21 kW.

[0057] The first adsorption section 12 and the second adsorption section 13 are considered capable of operating with a supply gas composition containing carbon dioxide (CO2) up to a time-averaged 20 ppm at a dew point of -20°C (assuming no flow unevenness issues and that all one or more adsorbents are fully regenerated). Therefore, it will be understood that the first auxiliary adsorption section 12 and the second auxiliary adsorption section 13 described herein may be oversized to obtain desired operating characteristics. The length of the first auxiliary adsorption section 12 and the second auxiliary adsorption section 13 can be increased to reduce the size of the adsorbent bed in the main adsorption section 11 and allow more carbon dioxide (CO2) to pass through. However, the carbon dioxide (CO2) regenerated from the first adsorption section 12 and the second adsorption section 13 is sent back to the main adsorption section 11 and recaptured in the adsorption bed.

[0058] By using the blower 32 with the second adsorption unit 13, the regeneration of the adsorbent can be completed when the process running in the main adsorption unit 11 is offline. Although the heating time is only 1 hour, a cooling step of more than 5 hours is required to push the heat out through the container from the other end. Even if the main process is shut down during this time, the blower can circulate the flow in the system and maintain the flow rate of 1800 Nm3 / h required for regeneration. The regenerated floor can be kept offline until the supply floor sees 6 hours of supply gas, after which it can be switched over. During this offline regeneration, a small amount of external gas may need to be supplied to maintain the pressure in the system. Once the cooling step is performed, the reduction in floor temperature causes air to be adsorbed onto the adsorbent, reducing the pressure in the system. This is a very small flow rate and may not actually be necessary.

[0059] The first auxiliary adsorption unit 12 and the second auxiliary adsorption unit 13 are interchangeable. The apparatus 10 is reconfigured to change (or swap) the operation of the first auxiliary adsorption unit 12 and the second auxiliary adsorption unit 13. In particular, the apparatus 10 is reconfigured so that the second auxiliary adsorption unit 13 dries (and / or cleans) the process gas discharged from the main adsorption unit 11 and the first auxiliary adsorption unit 12 is regenerated. Figure 3 shows a schematic diagram of the apparatus 10 in this configuration. In this configuration, the drying process gas is discharged from the second auxiliary adsorption unit 13. To perform regeneration, at least a portion of the drying process gas can be selectively supplied from the second auxiliary adsorption unit 13 to the first auxiliary adsorption unit 12. The apparatus 10 can be reconfigured automatically or semi-automatically. For example, one or more control valves can be provided to control the fluid connection between the main adsorption unit 11 and each of the first auxiliary adsorption unit 12 and the second auxiliary adsorption unit 13. Each control valve may consist of an actuator, such as a solenoid or electromechanical actuator, to control its opening and closing. The supply of the drying process gas through the transfer conduit 26 may be reversed to carry out regeneration of the first auxiliary adsorption unit 12. In this configuration, the heater 28 can be used to heat the drying process gas discharged from the second auxiliary adsorption unit 13.

[0060] Next, the operation of the apparatus 10 will be described with reference to the first block diagram 100 shown in Figure 4. The process gas is supplied to the main adsorption unit 11 by a compressor (block 105). In this embodiment, the process gas is air. The main adsorption unit 11 dries the process gas (block 110). The process gas is discharged from the main adsorption unit 11 to the first auxiliary adsorption unit 12 (block 115). The first auxiliary adsorption unit 12 performs auxiliary drying of the process gas (block 120). The dried process gas is discharged from the first auxiliary adsorption unit 12 for use downstream (block 125). A portion of the dried process gas is transferred to the second auxiliary adsorption unit 13 (block 130). The heater 28 operates to heat the dried process gas during the heating stage (block 135).

[0061] The heater 28 heats the drying process gas to a predetermined temperature, for example, 200°C (block 140). The heated drying process gas is supplied to the second auxiliary adsorption unit 13, heating the adsorbents within it (block 145). The supply of heated drying process gas is maintained for a first period, for example, 1 hour. The heater 28 stops operating (block 150). The (unheated) drying process gas is supplied to the second auxiliary adsorption unit 13 (block 155). The supply of (unheated) drying process gas is maintained for a second period, for example, 5 hours. The regenerated gas from the second auxiliary adsorption unit 13 is cooled and returned to the inlet of the main adsorption unit 11 (block 160). Once the regeneration of the second auxiliary adsorption unit 13 is complete, the apparatus 10 is reconfigured to regenerate the first auxiliary adsorption unit 12 (block 165). The process gas is supplied from the main adsorption unit 11 to the second auxiliary adsorption unit 13 (block 170). The second auxiliary adsorption unit 13 operates to dry the process gas while the first auxiliary adsorption unit 12 is being regenerated (block 175). The process continues to alternate between the first auxiliary adsorption unit 12 and the second auxiliary adsorption unit 13 in different functions to maintain effective drying (and cleaning) of the process gas.

[0062] Figure 5 shows a schematic diagram of the ECU. The ECU consists of at least one electronic processor 33 and a memory system 34. A set of calculation instructions 35 are stored on the memory system 34. The electronic control unit ECU includes one or more inputs 36A for receiving one or more input signals SIN-n from, for example, one or more sensors (not shown), and one or more outputs 36B for outputting one or more output signals SOUT-n. When the calculation instructions 35 are executed, the electronic control unit ECU causes the electronic control unit ECU to perform one or more methods described herein. The electronic control unit ECU controls the apparatus 10 to perform at least one of regeneration and drying of the process gas. In particular, the electronic control unit ECU is operable to configure the apparatus 10 so that either the first auxiliary adsorption unit 12 or the second auxiliary adsorption unit 13 is fluidly connected to the main adsorption unit 11. The electronic control unit ECU can reconfigure the apparatus 10 by, for example, outputting a control signal SOUT-n to a control valve. The electronic control unit (ECU) is configured to output a control signal Sn for controlling the operation of the heater 28, the cooler 31, and the blower 32. The electronic control unit (ECU) is connected to a human-machine interface (HMI) 37 and can receive user input. The electronic control unit (ECU) may be implemented in a proprietary system or in a general-purpose arithmetic unit.

[0063] It will be understood that various modifications can be made to one or more embodiments described herein without departing from the scope of the attached claims. Apparatus 10 circulates the process gas between a first auxiliary adsorption unit 12 and a second auxiliary adsorption unit 13 for drying. Each adsorption unit alternately repeats drying (adsorption) and regeneration. It will be understood that apparatus 10 may comprise two or more adsorption units, for example, a first adsorption unit, a second adsorption unit, and a third adsorption unit. Apparatus 10 can circulate between the first adsorption unit, the second adsorption unit, and the third adsorption unit.

[0064] It has been explained that the first auxiliary adsorption unit 12 and the second auxiliary adsorption unit 13 are provided within the corresponding first container 18 and second container 19. It will be understood that the first auxiliary adsorption unit 12 and the second auxiliary adsorption unit 13 may be located within the same container, for example, within the corresponding first chamber and second chamber. Furthermore, the first auxiliary adsorption unit 12 and the second auxiliary adsorption unit 13 may also be combined with the main adsorption unit 11, for example, in separate chambers.

[0065] [Table 1]

Claims

1. A device (10) for drying process gas, A main adsorption unit (11) comprising one or more adsorbents for processing process gas, wherein the main adsorption unit (11) has an inlet (14) for receiving the process gas from a compressor (P) and an outlet (16) for discharging the process gas, A first auxiliary adsorption section (12) containing an adsorbent for adsorbing moisture, A second auxiliary adsorption section (13) containing an adsorbent for adsorbing moisture, Equipped with, The apparatus (10) is configured to fluidly connect the outlet (16) of the main adsorption unit (11) to a selected one of the first auxiliary adsorption unit (12) and the second auxiliary adsorption unit (13), and the selected one of the first auxiliary adsorption unit (12) and the second auxiliary adsorption unit (13) is operable to adsorb moisture to dry the process gas discharged from the main adsorption unit (11) and to discharge the dried process gas. The apparatus (10) is configured to supply a regeneration gas to the other of the first auxiliary adsorption section (12) and the second auxiliary adsorption section (13) in order to regenerate the adsorbent disposed in the other of the first auxiliary adsorption section (12) and the second auxiliary adsorption section (13). The apparatus (10) is configured to dry a process gas, wherein, after the regenerated gas has been supplied to the other of the first auxiliary adsorption section (12) and the second auxiliary adsorption section (13), the regenerated gas is introduced into the inlet (14) of the main adsorption section (11) to regenerate the adsorbent disposed in the main adsorption section (11).

2. The apparatus (10) according to claim 1, wherein the regenerated gas includes at least a portion of the drying process gas discharged from one of the first auxiliary adsorption unit (12) and the second auxiliary adsorption unit (13).

3. The apparatus (10) according to claim 2, further comprising a transfer conduit (26) for supplying the drying process gas to a selected one of the first auxiliary adsorption unit (12) and the second auxiliary adsorption unit (13).

4. The apparatus (10) according to any one of claims 1, 2, or 3, further comprising a heater (28) for heating the regenerated gas.

5. The apparatus (10) according to claim 4, wherein during the regeneration process, the heater (28) is activated for a first period to heat the regeneration gas, and then deactivated for a second period, and the regeneration gas is supplied throughout the regeneration process.

6. The apparatus (10) according to claim 5, wherein the second period is longer than the first period.

7. The apparatus (10) according to claim 1, further comprising a cooler for cooling the regenerated gas prior to its introduction into the main adsorption section (11).

8. The apparatus (10) according to claim 1 or 7, further comprising a compressor (32) for compressing the regenerated gas prior to its introduction into the main adsorption section (11).

9. The apparatus (10) according to any one of claims 1, 2, 3, or 7, wherein the apparatus (10) is configured to change the selected one of the first auxiliary adsorption unit (12) and the second auxiliary adsorption unit (13) so that the other of the first auxiliary adsorption unit (12) and the second auxiliary adsorption unit (13) operates to dry the process gas and discharge the dried process gas.

10. A method for drying process gases, The steps include supplying process gas to the inlet (14) of a main adsorption section (11) which includes one or more adsorbents for processing the process gas, The steps include: discharging the process gas from the main adsorption unit (11); The main adsorption unit (11) is fluidly connected to a selected one of a first auxiliary adsorption unit (12) and a second auxiliary adsorption unit (13), and the process gas is selectively supplied from the main adsorption unit (11) to at least one of the first auxiliary adsorption unit (12) and the second auxiliary adsorption unit (13), the selected one of the first auxiliary adsorption unit (12) and the second auxiliary adsorption unit (13) adsorbs moisture to dry the process gas, and the dried process gas is discharged. The steps include supplying a regenerating gas to the other of the first auxiliary adsorption section (12) and the second auxiliary adsorption section (13) to regenerate the adsorbent disposed in the other of the first auxiliary adsorption section (12) and the second auxiliary adsorption section (13), After being supplied to the other of the first auxiliary adsorption unit (12) and the second auxiliary adsorption unit (13), the regenerated gas is introduced into the inlet (14) of the main adsorption unit (11) to regenerate the adsorbent placed in the main adsorption unit (11), A method for drying process gases, including [the specified substance].

11. The method according to claim 10, wherein the regenerated gas comprises at least a portion of the drying process gas discharged from one of the first auxiliary adsorption unit (12) and the second auxiliary adsorption unit (13).

12. The method according to claim 10 or 11, further comprising the step of heating the regenerated gas.

13. The method according to claim 12, further comprising the step of supplying heated regeneration gas for a first period and unheated regeneration gas for a second period during the regeneration process.

14. The method according to claim 13, wherein the second period is longer than the first period.

15. The method according to claim 10, further comprising the step of cooling the regenerated gas before introducing it into the main adsorption section (11).

16. The method according to claim 10 or 15, further comprising the step of compressing the regenerated gas prior to introducing it into the main adsorption section (11).

17. The method according to any one of claims 10, 11, or 15, further comprising the step of modifying a selected one of the first auxiliary adsorption unit (12) and the second auxiliary adsorption unit (13) so that the other of the first auxiliary adsorption unit (12) and the second auxiliary adsorption unit (13) operates to dry the process gas and discharge the dried process gas.

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