A pressure swing adsorption oxygen generation system based on waste heat recovery

Abstract

The present application relates to pressure swing adsorption oxygen production system technical field, especially to a kind of based on waste heat recycling's pressure swing adsorption oxygen production system, including pressure swing adsorption oxygen production module, air compressor heat exchange module, constant temperature pretreatment module, temperature monitoring module and waste heat delivery control module, waste heat delivery control module is used to judge whether to open heat energy storage device to store energy according to current external environment temperature, the heat exchange sequence of heat exchange pipeline is judged based on external environment temperature, the current heat energy storage state of heat energy storage device, and the heat exchange amount of each heat exchange pipeline is adjusted according to the working efficiency of molecular sieve, the waste heat of compressor for pressurizing external air is all transferred to constant temperature pretreatment module and heat energy storage device in the present application, avoid using heater to heat compressed air again, reduce energy consumption.

Description

Technical Field

[0001] This invention relates to the field of pressure swing adsorption (PSA) oxygen generation systems, and more particularly to a PSA oxygen generation system based on waste heat recovery. Background Technology

[0002] Current pressure swing adsorption (PSA) oxygen generation systems mainly consist of two adsorption towers containing adsorbent materials and inlet valves, outlet valves, equalizing valves, and flushing valves installed within the towers. During the intake phase, the compressed air entering the towers is not dried, leading to the introduction of water molecules from the compressed air, which can cause the adsorbent materials to become ineffective. Furthermore, the waste heat generated by the air compressor and heat exchanger used to produce the compressed air is generally not effectively utilized, increasing the overall energy consumption of the oxygen generation system and resulting in energy waste. Therefore, developing a PSA oxygen generation system that can dry the compressed air entering the adsorption towers and recover waste heat is of significant practical importance.

[0003] Chinese Patent Publication No. CN115445386B discloses an energy-saving pressure swing adsorption (PSA) oxygen generation and constant temperature system, including a temporary storage tank, a finned heat exchange circuit, a gas pipe, an electric heater, an oxygen generator main unit, and a temperature sensor. It utilizes the waste heat from the air compressor and the electric heater to heat the standby raw gas, stabilizing its temperature within a set range. However, this energy-saving PSA oxygen generation and constant temperature system has the following problems: it still requires the electric heater to heat the standby raw gas, and it cannot fully utilize the waste heat generated by the air compressor in the oxygen pretreatment stage, increasing the energy consumption of the oxygen pretreatment stage. Summary of the Invention

[0004] Therefore, the present invention provides a pressure swing adsorption oxygen generation system based on waste heat recovery and utilization, in order to overcome the problem that the existing technology cannot make full use of waste heat.

[0005] To achieve the above objectives, the present invention provides a pressure swing adsorption oxygen generation system based on waste heat recovery, comprising:

[0006] A pressure swing adsorption oxygen generation module includes a molecular sieve for separating compressed air, a pressure swing chamber for containing the molecular sieve and the separated gas, a PSA valve group for controlling the working state of pressure swing adsorption, and a drying tank for drying the compressed air.

[0007] The air compressor heat exchange module, which is connected to the pressure swing adsorption oxygen generation module, includes a compressor for pressurizing the outside air, an air compressor heat exchanger disposed outside the compressor for exchanging heat with the compressor, and a thermal energy storage device for storing thermal energy, which is connected to the air compressor heat exchanger and the PSA valve group respectively.

[0008] The constant temperature pretreatment module is connected to the air compressor heat exchange module and includes several heat exchange pipelines for exchanging heat from the air compressor heat exchanger / heat storage device to the drying tank, the PSA valve group or the transformer chamber.

[0009] A temperature monitoring module is connected to the pressure swing adsorption oxygen generation module, the air compressor heat exchange module and the constant temperature pretreatment module respectively, and is used to obtain the external ambient temperature, the gas temperature in the pressure swing chamber, the temperature of the PSA valve group and the temperature of the compressed air, as well as the outer wall temperature of the compressor and the thermal energy stored in the thermal energy storage device.

[0010] The waste heat transfer control module is connected to the pressure swing adsorption oxygen generation module, the air compressor heat exchange module, the constant temperature pretreatment module, and the temperature monitoring module, respectively. It is used to determine whether to activate the thermal energy storage device for energy storage based on the current external ambient temperature, determine the heat exchange sequence of the heat exchange pipeline based on the external ambient temperature and the current thermal energy storage device, and adjust the heat exchange timing of the pressure swing chamber and the recovery trigger temperature according to the working efficiency of the molecular sieve.

[0011] Furthermore, the waste heat transfer control module determines to activate the thermal energy storage device for energy storage based on the judgment result that the external ambient temperature is less than the preset operating temperature threshold, and determines the PSA valve group as the first heat exchange sequence object.

[0012] Furthermore, the waste heat transfer control module determines the drying tank as the first heat exchange sequence object based on the judgment result that the current heat storage energy of the heat storage device is greater than the preset energy storage threshold.

[0013] Furthermore, the waste heat transfer control module is used to determine the target heat exchange temperature of the compressed air in the drying tank based on the gas temperature fluctuation curve in the variable pressure chamber.

[0014] Furthermore, the waste heat transfer control module determines the oxygen production temperature fluctuation difference based on the gas temperature fluctuation curve inside the variable pressure chamber, and determines the heat exchange target temperature based on the oxygen production temperature fluctuation difference and the external ambient temperature.

[0015] Furthermore, the waste heat transfer control module determines the timing of heat recovery based on the gas temperature fluctuation curve inside the transformer chamber, and controls the corresponding heat exchange pipeline to perform heat exchange to adjust the temperature of the transformer chamber.

[0016] Furthermore, the waste heat transport control module determines the recovery trigger temperature of the heat recovery section based on the gas temperature fluctuation curve in the variable pressure chamber to determine the timing of heat recovery, and determines the energy storage sequence of redundant heat energy based on the redundant heat energy in the heat recovery section and the current heat storage energy.

[0017] The energy storage sequence includes a first heat exchange sequence object and a second heat exchange sequence object.

[0018] Furthermore, the waste heat transfer control module determines the working efficiency of the molecular sieve based on the oxygen production of the variable pressure chamber, so as to adjust the recovery trigger temperature of the variable pressure chamber.

[0019] Furthermore, the waste heat transfer control module adjusts the preset energy storage threshold according to the external ambient temperature to adjust the heat exchange sequence of the heat exchange pipeline.

[0020] Furthermore, the waste heat transfer control module adjusts the heat exchange target temperature based on the adjusted recovery trigger temperature.

[0021] The decrease in the recovery trigger temperature is positively correlated with the increase in the heat exchange target temperature.

[0022] Compared with the prior art, the beneficial effect of the present invention is that the pressure swing adsorption oxygen generation system based on waste heat recovery and utilization of the present invention transfers all the waste heat of the compressor that pressurizes the outside air to the constant temperature pretreatment module and the thermal energy storage device through the air compressor heat exchanger set in the air compressor heat exchange module, avoiding the need to use a heater to heat the compressed air again and reducing energy consumption.

[0023] Furthermore, the pressure swing adsorption oxygen generation system based on waste heat recovery of this invention uses a temperature monitoring module to monitor the temperature of all components in the pressure swing adsorption oxygen generation module and the ambient temperature in real time, and transmits the detection results to the waste heat delivery control module to control the heat exchange sequence and heat exchange of the constant temperature pretreatment module, thereby improving the overall intelligence level of the equipment. Attached Figure Description

[0024] Figure 1 This is a connection block diagram of the pressure swing adsorption oxygen generation system based on waste heat recovery and utilization according to the present invention;

[0025] Figure 2 This is a connection block diagram of the temperature monitoring module of the present invention;

[0026] Figure 3 This is a flowchart illustrating the process of determining whether to activate the thermal energy storage device for energy storage according to the present invention. Detailed Implementation

[0027] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0028] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0029] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0030] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0031] Please see Figure 1 The diagram shown is a connection block diagram of the pressure swing adsorption (PSA) oxygen generation system based on waste heat recovery according to the present invention. An embodiment of the present invention provides a PSA oxygen generation system based on waste heat recovery, comprising:

[0032] A pressure swing adsorption oxygen generation module includes a molecular sieve for separating compressed air, a pressure swing chamber for containing the molecular sieve and the separated gas, a PSA valve group for controlling the working state of pressure swing adsorption, and a drying tank for drying the compressed air.

[0033] The air compressor heat exchange module, which is connected to the pressure swing adsorption oxygen generation module, includes a compressor for pressurizing the outside air, an air compressor heat exchanger disposed outside the compressor for exchanging heat with the compressor, and a thermal energy storage device for storing thermal energy, which is connected to the air compressor heat exchanger and the PSA valve group respectively.

[0034] The constant temperature pretreatment module is connected to the air compressor heat exchange module and includes several heat exchange pipelines for exchanging heat from the air compressor heat exchanger / heat storage device to the drying tank, the PSA valve group or the transformer chamber.

[0035] The temperature monitoring module is connected to the pressure swing adsorption oxygen generation module, the air compressor heat exchange module and the constant temperature pretreatment module respectively, and is used to obtain the external ambient temperature, the temperature of the gas in the pressure swing chamber, the temperature of the PSA valve group and the temperature of the compressed air, as well as the temperature of the outer wall of the compressor and the thermal energy storage status in the thermal energy storage device.

[0036] The waste heat transfer control module is connected to the pressure swing adsorption oxygen generation module, the air compressor heat exchange module, the constant temperature pretreatment module, and the temperature monitoring module, respectively. It is used to determine whether to activate the thermal energy storage device for energy storage based on the current external ambient temperature, determine the heat exchange sequence of the heat exchange pipeline based on the external ambient temperature and the current thermal energy storage status of the thermal energy storage device, and adjust the heat exchange capacity of each heat exchange pipeline according to the working efficiency of the molecular sieve.

[0037] The present invention is a pressure swing adsorption oxygen generation system based on waste heat recovery. By using an air compressor heat exchanger installed in the air compressor heat exchange module, all the waste heat from the compressor that pressurizes the outside air is transferred to the constant temperature pretreatment module and the thermal energy storage device, avoiding the need to use a heater to heat the compressed air again, and further reducing energy consumption.

[0038] Specifically, in the pressure swing adsorption (PSA) oxygen generation module, the molecular sieve is used to separate oxygen from other gases in the compressed air. For example, 13X or LiLSX molecular sieves are used to adsorb N2 and enrich O2. In practice, when the molecular sieve separates oxygen, the compressed air enters the molecular sieve at a specified flow rate. The molecular sieve filters the gas molecules in the compressed air, allowing oxygen molecules to pass through while adsorbing the remaining gas molecules inside the molecular sieve. Regeneration of the molecular sieve is achieved through depressurization or vacuum desorption.

[0039] Specifically, in the pressure swing adsorption oxygen generation module, the pressure swing chamber is designed to withstand negative pressure, with a maximum negative pressure of -65000Pa, and the molecular sieve is installed inside it.

[0040] In practice, before the molecular sieve performs oxygen separation, the pressure swing chamber should be evacuated to prevent other gases from entering and affecting the oxygen concentration within the chamber. After compressed air enters the chamber, the molecular sieve enriches O2. When the oxygen concentration in the chamber reaches a predetermined range, the molecular sieve suspends oxygen separation. After all the oxygen in the chamber has entered the next stage, the molecular sieve depressurizes or evacuates to desorb N2. After desorption, the next round of oxygen separation begins. The predetermined oxygen concentration range in the pressure swing chamber is 80%–95%.

[0041] Specifically, in the pressure swing adsorption oxygen generation module, the drying tank is filled with an adsorption desiccant connected to the molecular sieve to pre-adsorb moisture in the compressed air, thus avoiding affecting the separation effect of the molecular sieve.

[0042] During implementation, when the pressure inside the drying tank reaches the predetermined pressure range, the air intake of the drying tank should be stopped. After the molecular sieve has been working for 2 minutes, the air intake can be resumed to avoid excessive air pressure inside the drying tank and potential accidents.

[0043] Specifically, in the pressure swing adsorption (PSA) oxygen generation module, the PSA valve group is connected to the molecular sieve, the pressure swing chamber, and the drying tank, and is used to control the pressure of the molecular sieve, the pressure inside the pressure swing chamber, the inlet flow rate of the pressure swing chamber, the outlet flow rate of the pressure swing chamber, the inlet flow rate of the drying tank, and the outlet flow rate of the drying tank, thereby driving the PSA oxygen generation module to operate. The specific control process includes:

[0044] When the pressure swing adsorption (PSA) oxygen generation module generates oxygen, the vacuum function of the PSA chamber is activated. After a vacuum environment is reached in the PSA chamber, the air inlet flow rate of the drying tank is appropriately increased according to the pressure in the drying tank to dry the compressed air input to the drying tank. When the pressure in the drying tank reaches the predetermined pressure range, the air inlet flow rate of the drying tank is reduced and the air outlet flow rate of the drying tank is increased to input the dried compressed air into the PSA chamber. As the pressure in the PSA chamber increases with the input of compressed gas, the compressed air undergoes oxygen separation through the molecular sieve. The molecular sieve adsorbs N2 from the compressed air to achieve oxygen generation. After oxygen separation begins, the air inlet flow rate of the PSA chamber is increased to maintain a high-pressure environment in the high-pressure chamber. After pressure equilibrium is reached, the separated oxygen is output outside the PSA chamber. After oxygen separation is completed, the pressure in the PSA chamber is reduced or vacuum desorption is performed to discharge the adsorbed gas from the molecular sieve. The molecular sieve is regenerated, and one round of oxygen generation is completed.

[0045] Because the pressure-switching chamber involves pressurization and depressurization processes during oxygen production via molecular sieves, these pressure changes lead to temperature fluctuations within the chamber. This results in the molecular sieve operating in a temperature-fluctuating environment, affecting its oxygen production efficiency. Excessively high or low temperatures beyond the molecular sieve's operating range can negatively impact both the oxygen production rate and the sieve's lifespan. Therefore, temperature fluctuation control is typically necessary to ensure the molecular sieve functions properly and maintains high oxygen production efficiency and a long lifespan. This invention addresses this issue by rationally utilizing the temperatures at different oxygen production stages within the pressure-switching chamber, combined with the waste heat generated by the compressor during the oxygen production process. This efficient heat energy circulation within the oxygen production system effectively improves energy efficiency. Furthermore, by maintaining the pressure-switching chamber within a stable temperature range, the oxygen production efficiency and lifespan of the molecular sieve are further guaranteed.

[0046] Specifically, in the air compressor heat exchange module, the air compressor heat exchanger includes:

[0047] The air-compressed heat absorption pipeline is installed outside the compressor to exchange heat with the compressor and the compressed air.

[0048] The compressed air heat storage pipeline is connected to the compressed air heat absorption pipeline and the heat storage device respectively, and is used to exchange the heat energy in the compressed air heat absorption pipeline to the heat storage device for heat energy storage.

[0049] In practice, the air pressure heat exchanger may also include:

[0050] The heat exchanger housing is located outside the compressed air heat absorption pipeline to prevent heat exchange between the compressed air heat absorption pipeline and the external environment.

[0051] It is understandable that both the compressed air heat absorption pipeline and the compressed air heat storage pipeline are closed loop pipelines, which are filled with heat exchange medium (liquid) to carry out circulating heat exchange. The end of the compressed air heat absorption pipeline and the compressed air heat storage pipeline are coiled and arranged in contact inside the heat exchanger box to improve heat exchange efficiency.

[0052] In practice, when the compressor is working, the air pressure heat exchanger's air pressure heat absorption pipeline absorbs the working heat of the compressor and transfers it to the air pressure heat storage pipeline through heat exchange. The heat exchange medium in the air pressure heat exchange pipeline transfers the heat to one end of the heat storage device to exchange heat with the phase change energy storage material, and the phase change energy storage material stores the heat.

[0053] Specifically, in the air compressor heat exchange module, the thermal storage device includes:

[0054] Phase change energy storage materials are used to store or release heat exchanged in compressed air thermal storage pipelines through phase change. In this embodiment, the phase change energy storage material can be a paraffin-based phase change material or a composite phase change material with a phase change temperature of 30°C to 50°C. Preferably, the phase change temperature of the phase change energy storage material is set to 45°C.

[0055] A thermal energy storage enclosure is installed outside the PSA valve assembly to insulate the heat inside the thermal energy storage unit from the external environment.

[0056] The first heat circulation pipeline is a circulation pipeline filled with heat exchange medium, used to exchange heat with the phase change energy storage material to transfer heat to the drying tank.

[0057] In practice, the thermal energy storage device has two stages: energy storage and energy release. During energy storage, the air-compressed thermal energy storage pipeline exchanges the waste heat generated by the compressor to the phase change energy storage material for heat storage. During energy release, the first thermal circulation pipeline exchanges the heat of the phase change energy storage material to the drying tank to heat the compressed gas in the drying tank.

[0058] Specifically, in the constant temperature pretreatment module, the heat exchange pipeline includes:

[0059] The first heat exchange pipeline is a circulating pipeline filled with heat exchange medium. The two sides of the pipeline are connected to the air compressor heat exchanger and the drying tank, respectively, to exchange the heat in the air compressor heat exchanger's air compressor heat absorption pipeline to the drying tank to heat the dried compressed air.

[0060] The second heat exchange pipeline is a circulating pipeline filled with heat exchange medium. The pipeline is connected to the heat storage tank, the drying tank and the pressure transformer in sequence. It is used to exchange the heat of the heat storage tank to the drying tank and the pressure transformer in sequence, or to exchange the heat of the pressure transformer to the heat storage tank and the drying tank in sequence, so as to adjust the temperature of the drying tank and the pressure transformer.

[0061] The third heat exchange pipeline is connected to the transformer chamber and the thermal energy storage device on both sides, respectively, to exchange the heat from the transformer chamber to the thermal energy storage device for heat storage.

[0062] It is understood that the PSA valve assembly also includes a pipeline regulating valve for controlling the opening and closing, on / off state, and flow rate of the aforementioned pipelines.

[0063] Please see Figure 2 The diagrams shown are connection block diagrams of the temperature monitoring module of the present invention. The temperature monitoring module includes:

[0064] The temperature detection unit includes several temperature sensors, which are respectively connected to the pressure swing adsorption oxygen generation module, the air compressor heat exchange module and the constant temperature pretreatment module, to obtain the external ambient temperature, the temperature of the gas in the pressure swing chamber, the temperature of the PSA valve group, the temperature of the compressed air in the drying tube and the temperature of the outer wall of the compressor.

[0065] A thermal energy storage detection unit, which includes an energy storage temperature sensor and a thermal energy storage calculation unit, is used to determine the heat storage capacity of the phase change energy storage material, which is recorded as thermal energy storage.

[0066] The oxygen generation detection unit is used to obtain the oxygen generation capacity and compressed air intake capacity of the transformer chamber.

[0067] A data collection unit, which is connected to the temperature detection unit and the thermal energy storage detection unit, is used to record and store the data obtained by the temperature detection unit and the thermal energy storage detection unit;

[0068] It is understandable that the heat storage capacity of phase change energy storage materials can be calculated using any of the existing technologies, and no limitations or further details are provided here.

[0069] Specifically, the waste heat transfer control module includes:

[0070] The waste heat transfer analysis unit is used to determine whether to activate the thermal energy storage device for energy storage based on the current external ambient temperature, determine the heat exchange sequence of the heat exchange pipeline based on the external ambient temperature and the current thermal energy storage of the thermal energy storage device, and adjust the heat exchange timing and recovery trigger temperature of the pressure shifting chamber according to the working efficiency of the molecular sieve.

[0071] The waste heat transfer control unit is connected to the pressure swing adsorption oxygen generation module, the air compressor heat exchange module, the constant temperature pretreatment module, and the temperature monitoring module, respectively. It is used to control the PSA valve group and the pipeline regulating valves on each pipeline to perform corresponding functions in order to realize the analysis results of the waste heat transfer analysis unit.

[0072] In implementation, the waste heat transfer control unit converts the control functions corresponding to the analysis results of the waste heat transfer analysis unit into instructions that the PSA valve group and pipeline regulating valve can execute, and controls the working status of the PSA valve group and pipeline regulating valve in real time.

[0073] Please see Figure 3 As shown, this is a flowchart illustrating the process of determining the heat exchange sequence according to an embodiment of the present invention. In this embodiment, the waste heat transfer control module determines the heat exchange sequence by including...

[0074] The waste heat transfer control module determines whether to activate the thermal energy storage device for energy storage based on the current external ambient temperature.

[0075] If the current external ambient temperature is greater than or equal to the preset operating temperature threshold, it is determined that the thermal energy storage device does not need to store energy.

[0076] If the current external ambient temperature is lower than the preset operating temperature threshold, the thermal energy storage device is determined to start energy storage, and the PSA valve group is determined to be the first heat exchange sequence object.

[0077] It is understandable that when the external ambient temperature is lower than the preset operating temperature threshold, the PSA valve assembly may be affected by the external ambient temperature, causing the PSA valve assembly temperature to be lower than the normal operating temperature of the valve assembly, thus affecting the working performance of the PSA valve assembly. In this embodiment, since a heat storage device is installed outside the PSA valve assembly, it can play a role in compensating and adjusting the temperature of the PSA valve assembly. Therefore, by turning on the heat storage device to store heat, the PSA valve assembly can be kept within an appropriate operating temperature range.

[0078] In this embodiment, the preset operating temperature threshold is determined based on the operating temperature range of the PSA valve assembly and its temperature fluctuation curve. It can be understood that the temperature fluctuation curve of the PSA valve assembly is a curve showing the temperature change of the PSA valve assembly over time within a preset time range prior to the current moment. If the curve segment prior to the current moment shows a decreasing temperature trend, the preset operating temperature threshold is the maximum value of the PSA valve assembly's operating temperature range; conversely, if the curve segment prior to the current moment shows a increasing temperature trend, the preset operating temperature threshold is the minimum value of the PSA valve assembly's operating temperature range. This preset time range is typically between 2 and 4 hours prior to the current moment.

[0079] Please continue reading. Figure 3 As shown, the current thermal energy storage is the quantified value (heat storage) of the current thermal energy storage state of the thermal energy storage device. In practice, the thermal energy storage device has a maximum heat storage capacity, which is recorded as the preset maximum thermal energy storage value.

[0080] Specifically, the waste heat transfer control module determines the heat exchange sequence of the heat exchange pipeline based on the external ambient temperature and the current heat storage state of the heat storage device, including:

[0081] S100, when the external ambient temperature is lower than the preset operating temperature threshold, the PSA valve group is determined as the first heat exchange sequence object, and the thermal energy storage device is activated to store energy. At this time, the air compressor heat absorption pipeline and the air compressor heat storage pipeline are activated to exchange the waste heat of the compressor to the thermal energy storage device for storage, so that the phase change material is maintained within a certain temperature range, so as to maintain the PSA valve group within the operating temperature range. The drying tank and the transformer chamber do not exchange heat temporarily.

[0082] S200 continuously monitors the current thermal energy storage capacity of the thermal energy storage device.

[0083] S300 When the current thermal energy storage of the thermal energy storage device is greater than the preset energy storage threshold (usually taken as 0.75 to 0.9 times the preset maximum thermal energy storage value), the dryer is determined to be the first heat exchange sequence object. At this time, the thermal energy storage device has maintained the PSA valve group in the working temperature range and generated redundant heat, and it is determined that the compressed air in the dryer can be heated.

[0084] When the drying tank is determined to be the first heat exchange object, the first heat circulation pipeline is controlled to start working, and the phase change energy storage material is used to exchange heat to the drying tank to heat the compressed air in the drying tank.

[0085] The S400 continuously monitors the temperature of the compressed gas in the drying tank.

[0086] When the temperature of the compressed gas rises (temperature rise ≥ 3℃) and remains stable (temperature fluctuation less than ± 2℃ within 10 minutes after the rise), it is determined that the residual heat supplied by the compressor is sufficient, the drying tank is determined as the first heat exchange sequence object, the variable pressure chamber is determined as the second heat exchange sequence object, and step S700 is executed.

[0087] When the temperature of the compressed gas does not rise sufficiently (temperature rise value < 3℃) or cannot be maintained in a stable state, it is determined that the residual heat supplied by the compressor is insufficient, the variable pressure chamber is added as the second energy supply object, the thermal energy storage device is determined as the first heat exchange sequence object, the drying tank is determined as the second heat exchange sequence object, and step S500 is executed.

[0088] S500, the waste heat transfer control module determines the timing of heat recovery based on the gas temperature fluctuation curve in the transformer chamber, so as to control the heat exchange pipeline to adjust the temperature of the transformer chamber.

[0089] In implementation, the waste heat conveying control module determines the heat recovery trigger temperature based on the duration of the gas temperature being greater than the preset first recovery temperature in the gas temperature fluctuation curve inside the transformer chamber, and determines the timing of heat recovery based on the recovery trigger temperature.

[0090] It is understandable that the gas temperature inside the variable pressure chamber is in an endothermic or exothermic state depending on the oxygen production stage. In this embodiment, the preset first recovery temperature Hc is calculated based on the sum of 0.1 times the maximum temperature value in the gas temperature fluctuation curve inside the variable pressure chamber and the minimum working temperature within the working temperature range of the molecular sieve. The duration during which the gas temperature inside the variable pressure chamber is continuously higher than the preset first recovery temperature is recorded as the characteristic duration. The temperature adjustment coefficient k is calculated based on the characteristic duration Ta and the standard duration T0 to determine the recovery trigger temperature He.

[0091] Among them, the temperature adjustment coefficient k = Ta / T0, the recovery trigger temperature He = Hc×k, and preferably, the standard duration T0 is taken as 5min to 15min according to the efficiency of heat energy exchange.

[0092] Therefore, when the current gas temperature in the variable pressure chamber is greater than or equal to the recovery trigger temperature He, as continuously monitored, it is determined that the heat recovery opportunity has been reached. The second heat exchange pipeline is then activated to exchange the waste heat generated in the oxygen production in the variable pressure chamber with the heat storage device for storage. This allows the heat storage device to continuously heat the compressed air in the drying tank. At the same time, due to heat exchange, the gas and molecular sieve in the variable pressure chamber can be maintained within a certain operating temperature range, avoiding the decrease in adsorption efficiency caused by large fluctuations in the molecular sieve temperature and improving the lifespan of the molecular sieve.

[0093] S600 calculates the redundant thermal energy in the heat recovery section, obtains the current thermal storage energy, and determines the storage order of the redundant thermal energy based on the redundant thermal energy in the heat recovery section and the current thermal storage energy.

[0094] If the sum of the redundant thermal energy of the heat recovery section and the current thermal storage energy is greater than or equal to the preset energy storage threshold, the drying tank is determined as the first heat exchange sequence object, the variable pressure chamber is determined as the second heat exchange sequence object, and step S700 is executed.

[0095] If the sum of the redundant thermal energy of the heat recovery section and the current thermal storage energy is less than the preset energy storage threshold, the thermal storage device is determined as the first heat exchange sequence object, the drying tank is determined as the second heat exchange sequence object, and step S500 is executed.

[0096] S700, when the transformer chamber is determined to be the second heat exchange sequence object, the third heat exchange pipeline is started to work, and heat exchange compensation is performed on the low temperature period of the gas in the transformer chamber. The waste heat transfer control module determines the oxygen production temperature fluctuation difference according to the gas temperature fluctuation curve in the transformer chamber, and determines the heat exchange target temperature according to the oxygen production temperature fluctuation difference and the external ambient temperature. The heat exchange target temperature is the target temperature to which the gas in the transformer chamber is heated by the third heat exchange pipeline.

[0097] During implementation, the temperature of the gas inside the variable pressure chamber is continuously acquired to plot the gas temperature fluctuation curve inside the variable pressure chamber. The waste heat transfer control module determines the oxygen production temperature fluctuation difference based on the gas temperature fluctuation curve inside the variable pressure chamber, and determines the heat exchange target temperature based on the oxygen production temperature fluctuation difference and the external ambient temperature.

[0098] Specifically, the oxygen production temperature fluctuation difference ΔHz is the difference between the highest and lowest temperatures within the gas temperature fluctuation curve of the variable pressure chamber.

[0099] The heat exchange target temperature Hb = He - α × ΔHz - β × (Hw - Hw0), where α is the fluctuation coefficient, preferably 0.03 to 0.07, β is the environmental influence coefficient, preferably 0.05 to 0.1, Hw is the external ambient temperature, and Hw0 is the lowest external ambient temperature, usually -30℃.

[0100] S800: When the second or third heat exchange pipeline is in operation, the waste heat transfer control module determines the working efficiency of the molecular sieve based on the oxygen production of the variable pressure chamber, so as to adjust the recovery trigger temperature of the variable pressure chamber.

[0101] Specifically, the working efficiency of the molecular sieve is the ratio of the oxygen production of the pressure-switching chamber to the compressed air intake. The waste heat transfer control module has a preset working efficiency threshold for the molecular sieve (usually the average oxygen production rate of the molecular sieve). If the working efficiency of the molecular sieve is less than the working efficiency threshold, it is determined that the recovery trigger temperature of the pressure-switching chamber needs to be reduced to further reduce the temperature fluctuation of the pressure-switching chamber and keep the temperature of the molecular sieve within a smaller fluctuation range.

[0102] In practice, the reduction in the recovery trigger temperature per cycle is typically between (He-Hc)×0.1 and (He-Hc)×0.15.

[0103] Specifically, the waste heat transfer control module adjusts the heat exchange target temperature according to the adjusted recovery trigger temperature;

[0104] In practice, the decrease in the recovery trigger temperature is positively correlated with the increase in the heat exchange target temperature. As the recovery trigger temperature decreases, more heat energy is recovered. The smaller the decrease in the recovery trigger temperature, the less heat energy is recovered. Therefore, the amount of heat energy subsequently used to heat the low-temperature section is also less, and the amount of increase in the heat exchange target temperature that can heat the low-temperature section of the transformer chamber is also less.

[0105] The S900 continuously monitors the external ambient temperature. The waste heat transfer control module adjusts the preset energy storage threshold according to the external ambient temperature to adjust the heat exchange sequence of the heat exchange pipeline.

[0106] Specifically, if the external ambient temperature is higher than the preset energy storage adjustment temperature, the waste heat transfer control module will adjust the preset energy storage threshold to 0.7 times the currently set preset energy storage threshold.

[0107] If the external ambient temperature is less than or equal to the preset energy storage adjustment temperature, the waste heat transfer control module will not adjust the currently set preset energy storage threshold.

[0108] In practice, the energy storage adjustment temperature is set to 0.9 times the maximum value of the PSA valve group's operating temperature range.

[0109] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A pressure swing adsorption oxygen generation system based on waste heat recovery, characterized in that, include: A pressure swing adsorption oxygen generation module includes a molecular sieve for separating compressed air, a pressure swing chamber for containing the molecular sieve and the separated gas, a PSA valve group for controlling the working state of pressure swing adsorption, and a drying tank for drying the compressed air. The air compressor heat exchange module, which is connected to the pressure swing adsorption oxygen generation module, includes a compressor for pressurizing the outside air, an air compressor heat exchanger disposed outside the compressor for exchanging heat with the compressor, and a thermal energy storage device for storing thermal energy, which is connected to the air compressor heat exchanger and the PSA valve group respectively. The constant temperature pretreatment module is connected to the air compressor heat exchange module and includes several heat exchange pipelines for exchanging heat from the air compressor heat exchanger / heat storage device to the drying tank, the PSA valve group or the transformer chamber. A temperature monitoring module is connected to the pressure swing adsorption oxygen generation module, the air compressor heat exchange module and the constant temperature pretreatment module respectively, and is used to obtain the external ambient temperature, the gas temperature in the pressure swing chamber, the temperature of the PSA valve group and the temperature of the compressed air, as well as the outer wall temperature of the compressor and the thermal energy stored in the thermal energy storage device. The waste heat transfer control module is used to determine whether to activate the thermal energy storage device for energy storage based on the current external ambient temperature, determine the heat exchange sequence of the heat exchange pipeline based on the external ambient temperature and the current thermal energy storage of the thermal energy storage device, and adjust the heat exchange timing and recovery trigger temperature of the variable pressure chamber according to the working efficiency of the molecular sieve.

2. The pressure swing adsorption oxygen generation system based on waste heat recovery and utilization according to claim 1, characterized in that, The waste heat transfer control module determines to activate the thermal energy storage device for energy storage based on the judgment result that the external ambient temperature is less than the preset operating temperature threshold, and determines the PSA valve group as the first heat exchange sequence object.

3. The pressure swing adsorption oxygen generation system based on waste heat recovery and utilization according to claim 1, characterized in that, The waste heat transfer control module determines the drying tank as the first heat exchange sequence object based on the judgment result that the current heat storage energy of the heat storage device is greater than the preset energy storage threshold.

4. The pressure swing adsorption oxygen generation system based on waste heat recovery and utilization according to claim 3, characterized in that, The waste heat transfer control module is used to determine the target heat exchange temperature of the compressed air in the drying tank based on the gas temperature fluctuation curve in the variable pressure chamber.

5. The pressure swing adsorption oxygen generation system based on waste heat recovery and utilization according to claim 4, characterized in that, The waste heat transfer control module determines the oxygen production temperature fluctuation difference based on the gas temperature fluctuation curve inside the variable pressure chamber, and determines the heat exchange target temperature based on the oxygen production temperature fluctuation difference and the external ambient temperature.

6. The pressure swing adsorption oxygen generation system based on waste heat recovery and utilization according to claim 5, characterized in that, The waste heat transfer control module determines the timing of heat recovery based on the gas temperature fluctuation curve inside the transformer chamber, and controls the corresponding heat exchange pipeline to exchange heat and adjust the temperature of the transformer chamber.

7. The pressure swing adsorption oxygen generation system based on waste heat recovery and utilization according to claim 6, characterized in that, The waste heat transport control module determines the recovery trigger temperature of the heat recovery section based on the gas temperature fluctuation curve in the transformer chamber to determine the timing of heat recovery, and determines the energy storage sequence of redundant heat energy based on the redundant heat energy of the heat recovery section and the current heat storage energy. The energy storage sequence includes a first heat exchange sequence object and a second heat exchange sequence object.

8. The pressure swing adsorption oxygen generation system based on waste heat recovery and utilization according to claim 5 or 7, characterized in that, The waste heat transfer control module determines the working efficiency of the molecular sieve based on the oxygen production of the variable pressure chamber, so as to adjust the recovery trigger temperature of the variable pressure chamber.

9. The pressure swing adsorption oxygen generation system based on waste heat recovery and utilization according to claim 8, characterized in that, The waste heat transfer control module adjusts the preset energy storage threshold according to the external ambient temperature to adjust the heat exchange sequence of the heat exchange pipeline.

10. The pressure swing adsorption oxygen generation system based on waste heat recovery and utilization according to claim 8, characterized in that, The waste heat transfer control module adjusts the heat exchange target temperature according to the adjusted recovery trigger temperature. The decrease in the recovery trigger temperature is positively correlated with the increase in the heat exchange target temperature.

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