Gas adsorption apparatus and gas adsorption method

Abstract

To provide a technique which enable a heating medium to flow in an appropriate flowing direction according to amounts of treated gas to be adsorbed.SOLUTION: A gas adsorption device comprises: an adsorber that stores an adsorbing material for adsorbing specific gas to be adsorbed included in mixed gas; a purge gas supply part that supplies purge gas into the adsorber; a heating medium passage forming part that forms a heating medium passage through which a heating medium which exchanges heat with the adsorbing material flows; a heat medium feeding part that flows the heating medium into the heating medium passage and can change a flowing direction of the heating medium; and a control part that controls the gas adsorption device. The control part repeatedly executes an adsorbing step of making the adsorbing material adsorb the gas to be adsorbed, and a desorbing step of desorbing the gas to be adsorbed from the adsorbing material by supplying purge gas into the adsorber, which sets the flowing direction of the heating medium in the desorbing step in a flowing direction according to amounts of the treated gas to be adsorbed which gets in and out of the adsorber, after the adsorbing step is started until the desorbing step is finished.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a gas adsorption device and a gas adsorption method. [Background technology]

[0002] Conventionally, there are known techniques for using an adsorbent to adsorb and recover a specific adsorbed gas contained in a mixed gas. For example, Patent Document 1 discloses a technique for recovering an adsorbed gas by aligning the flow direction of a heat transfer medium in the opposite direction to the injection direction of hydrogen injected from a hydrogen injection unit to desorb the adsorbed gas from the adsorbent housed in an adsorber. Furthermore, Patent Document 2 discloses a technique for reducing power consumption by desorbing the adsorbed gas until the amount of adsorbed gas adsorbed in the adsorber reaches a target inventory amount during a desorption process. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6791177 [Patent Document 2] Patent Publication No. 2021-171727 Summary of the Invention [Problem to be solved by the invention]

[0004] However, there is still room for improvement in the desorption of adsorbed gas by flowing a heat transfer medium in Patent Document 1. The recovery by flow direction described in Patent Document 1 is effective when the amount of adsorbed gas entering and leaving the adsorber between the start of the adsorption process and the end of the desorption process is relatively large. However, when the amount of the adsorbed gas being processed is relatively small, the adsorbent may have a large unadsorbed portion after the desorption process. Because impurities can be adsorbed in the unadsorbed portion of the adsorbent, if the unadsorbed portion increases after the desorption process, the adsorbent is likely to have a large unadsorbed portion remaining after the adsorption process, which increases the possibility of impurities being mixed into the adsorbed gas recovered from the adsorbent. Furthermore, Patent Document 2 uses a heating device that circulates a heat transfer medium to desorb the adsorbed gas, but does not take into consideration the flow direction of the heat transfer medium.

[0005] The present invention has been made to solve at least some of the above-mentioned problems, and aims to provide a gas adsorption device that can circulate a heat transfer medium in an appropriate flow direction in accordance with the adsorption amount of the adsorbed gas. [Means for solving the problem]

[0006] The present invention has been made to solve at least part of the above-mentioned problems, and can be realized in the following aspects.

[0007] (1) According to one aspect of the present invention, there is provided a gas adsorption device comprising an adsorber containing an adsorbent that adsorbs a specific adsorbed gas contained in a mixed gas, a purge gas supply unit that supplies a purge gas into the adsorber, a heat medium flow path forming unit that forms a heat medium flow path through which a heat medium that exchanges heat with the adsorbent flows, a heat medium delivery unit that circulates the heat medium within the heat medium flow path and is capable of changing the flow direction of the heat medium, and a controller that controls the gas adsorption device, wherein the controller repeatedly executes an adsorption process in which the adsorbed gas is adsorbed by the adsorbent and a desorption process in which the purge gas is supplied into the adsorber to desorb the adsorbed gas from the adsorbent, and sets the flow direction of the heat medium in the desorption process to a flow direction that corresponds to the throughput of the adsorbed gas that flows in and out of the adsorber from the start of the adsorption process to the end of the desorption process.

[0008] According to this configuration, the flow direction of the heat medium in the desorption step is set to a flow direction corresponding to the amount of adsorbed gas entering and exiting the adsorber from the start of the adsorption step to the end of the desorption step. This flow direction includes a parallel direction, which is the same direction as the flow direction of the purge gas inside the adsorber, and a counter direction, which is the opposite direction to the flow direction of the purge gas inside the adsorber. When the amount of adsorbed gas being processed is relatively low under low load conditions, the recovery rate of the adsorbed gas is the same regardless of whether the heat medium is circulated in the parallel direction or the counter direction during the desorption step. However, flowing in the parallel direction can reduce the possibility of impurities being mixed into the recovered gas recovered from the adsorbent. On the other hand, when the amount of adsorbed gas being processed is relatively high under high load conditions, flowing the heat medium in the counter direction during the desorption step can increase the recovery rate of the adsorbed gas. Therefore, compared to a configuration in which the flow direction of the heat medium in the desorption process is constant regardless of the amount of adsorbed gas being processed, this configuration allows the flow direction of the heat medium in the desorption process to be changed to a parallel direction or an opposing direction depending on the amount of adsorbed gas being processed, so that the heat medium can be circulated in an appropriate flow direction that is in line with the amount of adsorbed gas being processed.

[0009] (2) In the gas adsorption device of the above configuration, the control unit may set the flow direction of the heat medium in the desorption process to one of a parallel direction that is the same direction as the flow direction of the purge gas inside the adsorber and a counter direction that is the opposite direction to the flow direction of the purge gas inside the adsorber, and then switch the flow direction to the other direction. When the heat transfer medium flows in the parallel direction, the amount of adsorbed gas desorbed from the adsorbent is smaller than when the heat transfer medium flows in the counter-flow direction. This reduces the amount of adsorbed gas remaining in the adsorbent after the desorption process (i.e., the unadsorbed portion where impurities can be adsorbed). As a result, the unadsorbed portion is further reduced after the subsequent adsorption process, reducing the possibility of impurities being mixed into the recovered gas from the adsorbent. However, the recovery rate of the adsorbed gas decreases as the load increases. On the other hand, when the heat transfer medium flows in the counter-flow direction, the amount of adsorbed gas desorbed from the adsorbent is greater than when the heat transfer medium flows in the parallel direction. However, this increases the amount of unadsorbed gas remaining in the adsorbent after the desorption process. This increases the likelihood of impurities being mixed into the recovered gas from the adsorbent. According to this configuration, by switching the flow direction of the heat transfer medium during the desorption process from one of the parallel direction and the opposing direction to the other, it is possible to reduce the unadsorbed portion in the adsorbent after the desorption process and to increase the recovery rate of the adsorbed gas during the desorption process.

[0010] (3) In the gas adsorption device of the above aspect, the control unit may switch the flow direction of the heat medium in the desorption step from the parallel direction to the opposing direction. According to this configuration, the heat transfer medium is first circulated in a parallel direction to reduce the unadsorbed portion in the adsorbent, and then in a counter direction to increase the amount of adsorbed gas desorbed from the adsorbent. This makes it possible to simultaneously reduce the unadsorbed portion in the adsorbent after the desorption process and increase the recovery rate of the adsorbed gas in the desorption process.

[0011] (4) In the gas adsorption device of the above configuration, the control unit may be configured to increase the parallel period during which the heat medium is circulated in the parallel direction in the desorption process as the processing volume decreases, and increase the opposing period during which the heat medium is circulated in the opposing directions in the desorption process as the processing volume increases. With this configuration, the parallel period and the opposing period can be adjusted according to the amount of adsorbed gas being processed, making it possible to more accurately achieve both reducing the unadsorbed portion in the adsorbent after the desorption process and increasing the recovery rate of the adsorbed gas through the desorption process.

[0012] (5) The gas adsorption device of the above aspect further includes a desorption amount acquisition unit that acquires the amount of the adsorbed gas desorbed from the adsorbent, and the control unit is configured to The length of the row period and the length of the opposing period may be corrected in accordance with the amount of desorption. With this configuration, if the amount of adsorbed gas desorbed during the parallel period is less than expected, the parallel period can be shortened and the counter period can be lengthened.Also, if the amount of adsorbed gas desorbed during the counter period is more than expected, the counter period can be shortened and the parallel period can be lengthened.

[0013] The present invention can be realized in various forms, for example, a gas adsorption method, a method for controlling a gas adsorption apparatus, a computer program for controlling a gas adsorption apparatus, a hydrocarbon production system, a methane production system, a method for controlling these systems, a computer program for controlling these systems, a server device for distributing these computer programs, a non-transitory storage medium on which the computer program is stored, and the like. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is an explanatory diagram illustrating the configuration of a gas adsorption device according to a first embodiment. [Figure 2] FIG. 3 is an explanatory diagram showing the switching between the steps in the first to third adsorption devices. [Figure 3] FIG. 4 is an explanatory diagram showing the flow direction of the heat medium in the desorption process. [Figure 4] FIG. 10 is an explanatory diagram showing recovery rates depending on the flow direction of the heat medium. [Figure 5] FIG. 10 is an explanatory diagram showing the adsorption amounts at the end of the adsorption step and at the end of the desorption step. [Figure 6] FIG. 10 is an explanatory diagram showing the distribution of the heat transfer medium in the flow direction in the desorption process. [Figure 7] FIG. 10 is an explanatory diagram showing test results obtained by examining the parallel period and the opposing period during the desorption process. [Figure 8] 10 is a flowchart illustrating an example of a procedure for a flow direction adjustment process. DETAILED DESCRIPTION OF THE INVENTION

[0015] First Embodiment FIG. 1 is an explanatory diagram illustrating the configuration of a gas adsorption apparatus 1 according to one embodiment of the present invention. The gas adsorption apparatus 1 is an apparatus that recovers a specific adsorbate gas from a mixed gas by adsorbing and desorbing the adsorbate gas contained in the mixed gas. The gas adsorption apparatus 1 includes a first adsorption device 10, a second adsorption device 20, a third adsorption device 30, a combustion facility 40, an exhaust gas supply flow path 50, a hydrogen supply source 60, a hydrogen supply flow path 70, a raw material gas flow path 80, a hydrocarbon synthesis device 90, a heat transfer medium flow path 100, and a control unit 110. The first to third adsorption devices 10, 20, and 30 are also collectively referred to simply as adsorbers.

[0016] The first adsorber 10 is a device for recovering a specific adsorbed gas. The first adsorber 10 contains a first adsorbent 12 that adsorbs the specific adsorbed gas contained in the mixed gas. In the gas adsorption device 1, the mixed gas is exhaust gas discharged from a combustion facility 40, and carbon dioxide (CO2) is the specific adsorbed gas. Examples of the first adsorbent 12 include zeolite, activated carbon, and silica gel. The second adsorber 20 and the third adsorber 30 are adsorbers similar to the first adsorber 10. The second adsorber 20 and the third adsorber 30 contain a second adsorbent 22 and a third adsorbent 32, respectively, similar to the first adsorbent 12 corresponding to the first adsorber 10. The first to third adsorbents 12, 22, and 32 are also collectively referred to simply as adsorbents. The first to third adsorbents 10, 20, and 30 are provided with temperature and pressure sensors (not shown) for measuring the temperature and pressure within the adsorber.

[0017] The combustion equipment 40 is a combustion furnace in a factory. The exhaust gas discharged from the combustion equipment 40 contains O2, N2, H20, etc. in addition to CO2 adsorbed by the first to third adsorbents 12, 22, and 32. The exhaust gas supply flow path 50 is a gas flow path for supplying the exhaust gas discharged from the combustion equipment 40 to the first to third adsorbers 10, 20, and 30, and is formed by a plurality of pipes. The pipes forming the exhaust gas supply flow path 50 are provided with a first exhaust gas supply valve 51, a second exhaust gas supply valve 52, and a third exhaust gas supply valve 53. These valves control the flow rate in each pipe. The opening and closing of each of the first to third exhaust gas supply valves 51 to 53 is controlled by a control unit 110, which will be described later. In addition, the pipes forming the exhaust gas supply flow path 50 are provided with a temperature sensor, a pressure sensor, a flow rate sensor, and a CO2 concentration sensor (not shown) for measuring the temperature, pressure, flow rate, and CO2 concentration of the exhaust gas.

[0018] In the exhaust gas supplied from the combustion equipment 40 to the first adsorber 10 via the first exhaust gas supply valve 51, CO2 contained in the exhaust gas is adsorbed by the first adsorbent 12. The remaining components of the exhaust gas are released to the outside through the first exhaust flow path 54. A first exhaust valve 57 is provided in the piping forming the first exhaust flow path 54. Meanwhile, in the exhaust gas supplied from the combustion equipment 40 to the second and third adsorber 20 and 30 via the second and third exhaust gas supply valves 52 and 53, CO2 contained in the exhaust gas is adsorbed by the second and third adsorbents 22 and 32, respectively. The remaining components of the exhaust gas are released to the outside through the second and third exhaust flow paths 55 and 56, respectively. The piping forming the second and third exhaust flow paths 55 and 56 is provided with second and third exhaust valves 58 and 59, respectively. The opening and closing of each of the first to third exhaust valves 57 to 59 is controlled by a control unit 110, which will be described later.

[0019] The hydrogen supply source 60 is a water electrolysis device. The hydrogen supply flow path 70 is a gas flow path for supplying H2 supplied from the hydrogen supply source 60 to the first to third adsorption devices 10, 20, and 30, and is formed by multiple pipes. The pipes forming the hydrogen supply flow path 70 are provided with a first hydrogen supply valve 71, a second hydrogen supply valve 72, a third hydrogen supply valve 73, and a fourth hydrogen supply valve 74. These valves are capable of adjusting the flow rate in each pipe. The opening and closing of each of the first to fourth hydrogen supply valves 71 to 74 is controlled by a control unit 110, which will be described later. The H2 supplied from the hydrogen supply source 60 to the first to third adsorption devices 10, 20, and 30 via the first to third hydrogen supply valves 71 to 73 is used as a purge gas for desorbing CO2 adsorbed in the first to third adsorbents 12, 22, and 32. In other words, the hydrogen supply source 60 serves as a purge gas supply unit that supplies purge gas to the first to third adsorption devices 10, 20, and 30. Furthermore, H 2 is supplied from the hydrogen supply source 60 to a raw material gas flow passage 80 (described later) via a fourth hydrogen supply valve 74, and is added to the raw material gas flowing through the raw material gas flow passage 80.

[0020] The raw material gas flow path 80 is a gas flow path for supplying the raw material gas containing H and CO delivered from the first to third adsorbers 10, 20, and 30 to the hydrocarbon synthesis apparatus 90, and is formed by multiple pipes. The pipes forming the raw material gas flow path 80 are provided with a first raw material gas supply valve 81, a second raw material gas supply valve 82, and a third raw material gas supply valve 83. These valves are capable of adjusting the flow rate within each pipe. The pipes forming the raw material gas flow path 80 are also provided with a vacuum pump 85. The vacuum pump 85 can reduce the pressure inside any of the first to third adsorbers 10, 20, and 30 spatially connected to the vacuum pump 85 when any of the first to third raw material gas supply valves 81 to 83 is opened. The pipes forming the raw material gas flow path 80 are also provided with a temperature sensor, a pressure sensor, a flow rate sensor, and a CO concentration sensor (not shown) for measuring the temperature, pressure, flow rate, and CO concentration of the raw material gas.

[0021] The hydrocarbon synthesis apparatus 90 is an apparatus that synthesizes methane by a methanation reaction using a raw material gas supplied from the first to third adsorbers 10, 20, and 30 via a raw material gas flow path 80. The heat medium flow path 100 is a flow path through which a heat medium flows that exchanges heat with the first to third adsorbents 12, 22, and 32, and is formed by a plurality of pipes (heat medium flow path forming portions). Heat generated in the hydrocarbon synthesis apparatus 90 by the methanation reaction is supplied to the first to third adsorbers 10, 20, and 30 via the heat medium flowing through the heat medium flow path 100. The pipe that forms the heat medium flow path 100 is provided with a first flow path switching valve 104, a second flow path switching valve 105, a third flow path switching valve 106, and a fourth flow path switching valve 107. The first to fourth flow path switching valves 104 to 107 are all three-way valves, and the first flow path 101, The flow path through which the heat medium flows is switched between the second flow path 102 and the third flow path 103. The first to third flow paths 101 to 103 are flow paths that pass between the outer pipe and the inner pipe of the first to third adsorbers 10, 20, and 30, which are configured as double pipes. For example, when the flow path through which the heat medium flows is switched to the first flow path 101, heat is supplied from the heat medium flowing through the first flow path 101 to the first adsorbent 12 accommodated in the first adsorber 10. In FIG. 1 , the portion of the first adsorber 10 through which the heat medium passes is illustrated by dotted hatching. In addition, a pump 108 and a temperature adjustment unit 109 are provided in the piping that forms the heat medium flow path 100. The pump 108 is a heat medium delivery unit that circulates the heat medium through the heat medium flow path 100 via the flow paths that are spatially connected to the pump 108 by switching the first to fourth flow path switching valves 104 to 107 among the first to third flow paths 101 to 103, and that can change the flow direction of the heat medium. The temperature adjustment unit 109 is a device that can adjust the temperature of the heat medium, and when the temperature of the heat medium heated in the hydrocarbon synthesis unit 90 is higher than the set temperature, it adjusts the temperature by adding a room-temperature heat medium. Furthermore, when the temperature is lower than the set temperature, in addition to adjusting the flow rate, it may also heat the heat medium to the set temperature using a heater or the like.

[0022] The control unit 110 is a computer including a ROM, a RAM, and a CPU, and performs overall control of the gas adsorption apparatus 1. The control unit 110 is electrically connected to the various valves and sensors (temperature sensors, flow rate sensors, concentration sensors, etc.) provided in each of the above-mentioned flow paths, as well as the various pumps and the temperature adjustment unit 109, and controls the various valves, pumps, temperature adjustment unit 109, etc. based on measurements and the like from the various sensors. The control unit 110 controls the purge gas supply, adsorption process, desorption process, cooling process, and heat medium delivery, which will be described later, as control processes.

[0023] FIG. 2 is an explanatory diagram showing switching between the adsorption process, desorption process, and cooling process in the first to third adsorption devices 10, 20, and 30. In the gas adsorption device 1, each of the first to third adsorption devices 10, 20, and 30 executes an adsorption process in which the adsorbent adsorbs CO2, a gas to be adsorbed, on the adsorbent; a desorption process in which CO2 is desorbed from the adsorbent while supplying H2, a purge gas, into the adsorption device after the adsorption process; and a cooling process in which the adsorbent is cooled after the desorption process. As shown in FIG. 2, the first to third adsorption devices 10, 20, and 30 repeat different processes in the order of cycle 1, cycle 2, and cycle 3. In this embodiment, the length of each process is 1800 seconds. That is, the control unit 110 causes the first to third adsorption devices 10, 20, and 30 to repeatedly execute the adsorption process, desorption process, and cooling process. The heat medium at room temperature is supplied to the adsorber during the adsorption process and the cooling process through a flow path (not shown) (a flow path different from the heat medium flow path 100) formed in each of the first to third adsorber 10, 20, 30. On the other hand, the heat medium that is heated is supplied to the adsorber during the desorption process through the heat medium flow path 100. In other words, the control unit 110 executes heat medium delivery to circulate the heat medium through the adsorber during the desorption process.

[0024] When the first adsorber 10 is in the adsorption process, the first exhaust gas supply valve 51 and the first exhaust valve 57 are in an open state, and the first hydrogen supply valve 71 and the first raw material gas supply valve 81 are in a closed state. In this state, CO2 contained in the exhaust gas supplied from the combustion equipment 40 to the first adsorber 10 is adsorbed by the first adsorbent 12. The remaining components of the exhaust gas are then released to the outside through the first exhaust flow path 54. During the adsorption process, a room-temperature heat medium is supplied to the first adsorber 10 through a flow path (not shown in the figure, which is different from the heat medium flow path 100) formed in the first adsorber 10, thereby cooling the first adsorbent 12.

[0025] When the first adsorber 10 is in the desorption process, the first exhaust gas supply valve 51 and the first exhaust valve 57 are closed, and the first hydrogen supply valve 71 and the first raw material gas supply valve 81 are open. In this state, H2 supplied to the first adsorber 10 from the hydrogen supply source 60 acts as a purge gas to desorb CO2 adsorbed in the first adsorbent 12. The desorbed CO2 is sent to the raw material gas flow path 80 together with H2 as raw material gas. During this process, the vacuum pump 85 is operated to reduce the pressure inside the first adsorption device 10, and the first to fourth flow path switching valves 104 to 107 are switched to switch the flow path through which the heat medium circulates from the second flow path 102 to the first flow path 101 (see FIG. 2). At this time, heat is supplied to the first adsorbent 12 accommodated in the first adsorption device 10 from the heat medium circulating through the first flow path 101 by the pump 108.

[0026] When the first adsorption device 10 is in the cooling step, the first exhaust gas supply valve 51 and the first exhaust valve 57 are closed, and the first hydrogen supply valve 71 and the first raw material gas supply valve 81 are also closed. During the cooling step, the flow path through which the heat medium flows is switched from the first flow path 101 to the third flow path 103 by switching the first to fourth flow path switching valves 104 to 107 (see FIG. 2). During the cooling step, a room-temperature heat medium is supplied to the first adsorption device 10 through a flow path (not shown in the figure) formed in the first adsorption device 10 (a flow path different from the heat medium flow path 100) to cool the first adsorbent 12.

[0027] When the second and third adsorption devices 20, 30 are performing the adsorption process, desorption process, and cooling process, respectively, each process is carried out by opening, closing, and switching the various valves of the second and third adsorption devices 20, 30 corresponding to the various valves of the first adsorption device 10, in the same manner as the first adsorption device 10 when performing the adsorption process, desorption process, and cooling process described above.

[0028] FIG. 3 is an explanatory diagram showing the flow direction of the heat medium in the desorption process. The flow direction of the heat medium in the desorption process refers to the flow direction of the heat medium flowing through the heat medium flow path 100. In this embodiment, the control unit 110 determines the flow direction of the heat medium in the desorption process as a flow direction corresponding to the amount of CO2 that enters and leaves the adsorber from the start of the adsorption process to the end of the desorption process. This flow direction includes the parallel direction shown in FIG. 3(A) and the opposing direction shown in FIG. 3(B). FIGS. 3(A) and 3(B) illustrate the parallel direction and the opposing direction using an adsorber 10a (containing an adsorbent 12a) similar to the first adsorber 10 as an example. As shown in FIG. 3(A), the parallel direction refers to the same direction (broken arrow) as the flow direction of the purge gas (solid arrow) inside the adsorber 10a. On the other hand, as shown in FIG. 3(B), the opposing direction refers to the opposite direction (broken arrow) to the flow direction of the purge gas (solid arrow) inside the adsorber 10a.

[0029] The temperature of the heat medium supplied to the adsorber 10a is highest at position IN where it enters the adsorber 10a, and decreases as it approaches position OT where it is discharged from the adsorber 10a to the outside. Therefore, the closer to position IN within the adsorber 10a, the more CO2 desorption from the adsorbent 12a is promoted. On the other hand, the closer to position IJ where hydrogen supplied to the adsorber 10a enters the adsorber 10a, the more CO2 desorption from the adsorbent 12a is promoted. As shown in FIG. 3(A), the amount of CO2 desorbed from the adsorbent 12a tends to be smaller when the heat medium is circulated in parallel directions (positions IN and IJ are on the same side) than when the heat medium is circulated in counter directions (positions IN and IJ are on opposite sides).

[0030] Figure 4 is an explanatory diagram showing the CO2 capture rate depending on the flow direction of the heat transfer medium in the desorption process. In Figure 4, the horizontal axis represents the load, and the vertical axis represents the CO2 capture rate. The load refers to the amount of CO2 that enters and leaves the adsorber from the start of the adsorption process to the end of the desorption process. Since the load varies depending on the flow rate of the flue gas supplied to the adsorber from the combustion equipment 40, the numerical value representing the load is set to 1.0 when a certain flow rate of flue gas is supplied to the adsorber from the combustion equipment 40, and 0.4, 0.6, and 0.8 when flue gas is supplied at flow rates that are 40%, 60%, and 80% of that flow rate, respectively. In the following explanation, a load less than 0.6 is referred to as a low load, a load between 0.6 and 1.0 is referred to as a medium load, and a load of 1.0 or more is referred to as a high load. The CO2 capture rate is the amount of CO2 desorbed from the adsorber in the desorption process divided by the amount of CO2 supplied to the adsorber in the adsorption process immediately preceding the desorption process. The solid line in Figure 4 indicates the desorption rate. The dashed line in FIG. 4 shows the results when the heat transfer medium was circulated in parallel directions in the desorption process, and the dashed line in FIG. 4 shows the results when the heat transfer medium was circulated in opposite directions in the desorption process.

[0031] As shown in Figure 4, at low loads (up to 0.6), the CO2 capture rate in the desorption process is the same regardless of whether the heat transfer medium is circulated in the parallel or counterflow direction. At medium to high loads (0.6 to 1.0), the CO2 capture rate decreases when the heat transfer medium is circulated in the parallel direction, but the CO2 capture rate is higher when the heat transfer medium is circulated in the counterflow direction compared to the parallel direction.

[0032] FIG. 5 is an explanatory diagram showing the CO2 adsorption amount in the adsorbent at the end of the adsorption process and the end of the desorption process. In FIG. 5, the horizontal axis represents the load, and the vertical axis represents the CO2 adsorption amount per weight of the adsorbent. FIG. 5(A) shows the results when the heat transfer medium was always circulated in parallel directions during the desorption process. FIG. 5(B) shows the results when the heat transfer medium was always circulated in counter directions during the desorption process. Points a1 to a8 shown in FIGS. 5(A) and 5(B) represent the CO2 adsorption amount at the end of the adsorption process, and points d1 to d8 represent the CO2 adsorption amount at the end of the desorption process. For example, the difference between points a1 and d1 represents the amount of CO2 recovered from the adsorber in the desorption process. The results shown in FIGS. 5(A) and 5(B) are averages of multiple results obtained by repeating the adsorption and desorption processes multiple times.

[0033] As explained in Figure 4, at low loads (up to 0.6), the CO2 capture rate during the desorption process is the same regardless of whether the heat transfer medium is flowed in the parallel or countercurrent direction. On the other hand, at low loads (up to 0.6), the CO2 adsorption amount at the end of the adsorption process when the heat transfer medium is always flowing in the parallel direction during the desorption process (points a1 and a2 in Figure 5(A)) is greater than the CO2 adsorption amount when the heat transfer medium is always flowing in the countercurrent direction during the desorption process (points a5 and a6 in Figure 5(B)). Therefore, the unadsorbed portion of the adsorbent (points d1 and d2 in Figure 5(A)) at the end of the desorption process is smaller (compared to points d5 and d6 in Figure 5(B)). (The unadsorbed portion here is represented by the length between the CO2 adsorption amount of 0.10 and points d1 and d2.) As explained in Figure 3, this is thought to be because CO2 is desorbed primarily from the adsorbent at one end compared to when the heat transfer medium is circulated in parallel (see Figure 3(A)) or counter-flow (see Figure 3(B)). Since impurities other than CO2 contained in the exhaust gas (e.g., nitrogen) may be adsorbed in the unadsorbed portion, the greater the unadsorbed portion, the greater the likelihood of impurities being mixed into the gas recovered from the adsorbent. Therefore, at low loads (up to 0.6), it is more advantageous to circulate the heat transfer medium in parallel during the desorption process in order to increase the CO2 purity of the gas recovered from the adsorbent.

[0034] As explained in FIG. 4, at medium to high loads (0.6 to 1.0), the CO2 capture rate decreases when the heat transfer medium is circulated in the parallel direction, whereas the CO2 capture rate is higher when the heat transfer medium is circulated in the counter direction compared to the parallel direction. Furthermore, as shown at point a8 in FIG. 5(B), at high loads (1.0), if the heat transfer medium is always circulated in the counter direction during the desorption process, the amount of CO2 adsorbed at the end of the adsorption process is somewhat higher, resulting in a smaller unadsorbed portion compared to low loads (up to 0.6) (points a5 and a6). Therefore, at high loads (1.0), it is advantageous to circulate the heat transfer medium in the counter direction during the desorption process in order to ensure the amount of CO2 captured from the adsorber while minimizing the unadsorbed portion. Thus, in the gas adsorption device 1, the control unit 110 controls the heat transfer medium flow direction during the desorption process to be parallel at low loads (up to 0.6) and counter at high loads (1.0). Next, the flow direction at a medium load (0.6 to less than 1.0) will be explained.

[0035] 6 is an explanatory diagram showing the distribution of the heat transfer medium in the flow direction in the desorption process. In FIG. 6, the horizontal axis indicates the load, and the vertical axis indicates the opposing period ratio. In FIG. 6, the opposing period ratio is The length of time per process is set to 1.0, and this is the ratio of the opposing period during which the heat medium flows in the opposing directions during the desorption process. For example, at low loads (up to 0.6), the heat medium always flows in the parallel period during the desorption process, and at high loads (1.0), the heat medium always flows in the opposing period during the desorption process. On the other hand, at medium loads (less than 0.6 to 1.0), as shown in FIG. 6, in the gas adsorption device 1, the control unit 110 controls the pump 108 to switch the heat medium flow direction during the desorption process from one of the parallel direction and the opposing direction to the other direction. That is, the control unit 110 changes the heat medium flow direction when delivering the heat medium during the desorption process. In this embodiment, the control unit 110 switches the heat medium flow direction during the desorption process from the parallel direction to the opposing direction. Furthermore, as shown in FIG. 6, at a medium load (between 0.6 and less than 1.0), the control unit 110 lengthens the parallel period as the amount of CO2 processed decreases (the load decreases), and lengthens the counter period as the amount of CO2 processed increases (the load increases).

[0036] Figure 7 is an explanatory diagram showing the test results when examining the parallel period and counter period during the desorption process at a medium load (0.8). In Figure 7, the horizontal axis represents the parallel period ratio, and the vertical axis represents the CO2 capture rate (similar to Figure 4) and the CO2 adsorption amount in the adsorbent after the adsorption process. In Figure 7, the parallel period ratio is the ratio of the parallel period during the desorption process, with the length of time per desorption process set to 1.0. For example, when the parallel period ratio is 1, the entire desorption process is a parallel period, and when the parallel period ratio is 0, the entire desorption process is a counter period. Furthermore, when the parallel period ratio is 0.5, the first half of the desorption process is a parallel period, and the second half is a counter period. In other words, Figure 7 shows results when the parallel period ratio during the desorption process increases toward the right side of the figure. The black circles represent the CO2 capture rate. The black rectangles represent the CO2 adsorption amount in the adsorbent after the adsorption process.

[0037] As shown by the black rectangles in Figure 7, the higher the parallel period ratio, the greater the CO2 adsorption amount in the adsorbent after the adsorption step; and the lower the parallel period ratio (the higher the proportion of the counter periods), the smaller the adsorption amount. On the other hand, as shown by the black circles in Figure 7, the higher the parallel period ratio, the smaller the CO2 capture rate, and the lower the parallel period ratio (the higher the proportion of the counter periods), the larger the CO2 capture rate. Based on the results shown in Figure 7, it is preferable to set the parallel period ratio in the desorption step at a medium load (0.8) within the range of 0.6 to 0.8. Within this range, the CO2 adsorption amount in the adsorbent after the adsorption step can be increased without decreasing the CO2 capture rate. Furthermore, if the CO2 adsorption amount in the adsorbent after the adsorption step is high, it is likely that the unadsorbed portion in the adsorbent after the desorption step can be reduced, reducing the possibility of impurities being mixed into the gas recovered from the adsorbent.

[0038] 8 is a flowchart showing an example of the procedure for the flow direction adjustment process. The flow direction adjustment process is a process in which the control unit 110 adjusts the flow direction of the heat medium in the desorption process in accordance with the CO2 processing amount entering and leaving the adsorber from the start of the adsorption process to the end of the desorption process. Therefore, the flow direction adjustment process is performed on the adsorber that starts the desorption process among the first to third adsorber 10, 20, 30. Hereinafter, in the description of the flow direction adjustment process, the adsorber that is the target of the flow direction adjustment process among the first to third adsorber 10, 20, 30 will be referred to as the target adsorber, and the adsorbent housed in the target adsorber will be referred to as the target adsorbent.

[0039] When the flow direction adjustment process is started, the control unit 110 first acquires the CO2 throughput Ga to be processed in the target adsorber (step S10). As described above, the CO2 throughput Ga is the amount of CO2 that flows in and out of the adsorber from the start of the adsorption process to the end of the desorption process. At this time, the control unit 110 uses information (information about the exhaust gas supplied from the combustion equipment 40 to the target adsorber) received from a temperature sensor, a pressure sensor, a flow rate sensor, and a CO2 concentration sensor (not shown) that are provided in the piping that forms the exhaust gas supply flow path 50 to acquire the CO2 throughput Ga. The CO2 throughput Ga to be processed by the target adsorber is calculated from a relational expression, map, etc. prepared in advance.

[0040] Next, the control unit 110 acquires the amount of CO2 used in the synthesis of methane by the hydrocarbon synthesis unit 90 (step S20). The control unit 110 acquires the amount of CO2 used in the synthesis of methane from a relational expression, map, or the like prepared in advance, with reference to the CO2 processing amount Ga acquired in step S10.

[0041] Next, the control unit 110 determines the desorption conditions (step S30). The desorption conditions include the amount of H supplied from the hydrogen supply source 60 to the target adsorber during the desorption step and the length of the operation period of the vacuum pump 85. The control unit 110 determines the desorption conditions according to the CO2 processing amount Ga acquired in step S10.

[0042] Next, the control unit 110 determines whether the CO2 throughput Ga is smaller than the reference throughput Gthr (step S40). The reference throughput Gthr is a reference value for distinguishing whether the CO2 throughput Ga is a medium load or lower or a high load (see FIG. 6). If the CO2 throughput Ga is larger than the reference throughput Gthr, i.e., if the CO2 throughput Ga is a high load (step S40: NO), the control unit 110 adjusts the flow direction of the heat medium in the target adsorber to the opposing direction (step S100), starts the desorption process in the target adsorber, and then ends the flow direction adjustment process. The heat medium continues to flow in the opposing direction until the next cooling process is started. In this embodiment, the length of each process is 1800 seconds. Therefore, if the CO2 throughput Ga is a high load (step S40: NO), the heat medium is circulated in the opposing direction for 1800 seconds.

[0043] On the other hand, if the CO2 treatment rate Ga is smaller than the reference treatment rate Gthr, i.e., if the CO2 treatment rate Ga is a low load or a medium load (step S40: YES), the control unit 110 acquires the switching timing Tthr (step S50). The switching timing Tthr is the timing when the heat medium first flows in the parallel direction after the desorption process is started, and then switches to flow in the counter direction. The control unit 110 acquires the switching timing Tthr corresponding to the CO2 treatment rate Ga from a memory unit (not shown). This switching timing Tthr is set so that the parallel period becomes longer as the CO2 treatment rate Ga becomes smaller (the load becomes lower). Note that if the CO2 treatment rate Ga is considered to be a low load, the corresponding switching timing Tthr is the timing to switch the flow direction from the parallel direction to the counter direction when the desorption process ends (i.e., the heat medium flows in the counter direction for 1800 seconds, and then switches to the counter direction). In this case, the time the heat medium flows in the counter direction is substantially zero. After acquiring the switching timing Tthr (step S50), the control unit 110 changes the flow direction of the heat medium in the target adsorber to the parallel direction (step S60), and causes the target adsorber to start the desorption process.

[0044] Next, the control unit 110 determines whether the desorption process elapsed period T has passed the switching timing Tthr (step S70). The desorption process elapsed period T is the period that has passed since the target adsorber started the desorption process. If the desorption process elapsed period T has passed the switching timing Tthr (step S70: YES), the control unit 110 switches the flow direction of the heat medium in the target adsorber to the opposing direction (step S100), and then ends the flow direction adjustment process. The heat medium continues to flow in the opposing direction until the next cooling process starts.

[0045] On the other hand, if the desorption process elapsed period T has not passed the switching timing Tthr (step S70: NO), the control unit 110 determines whether the actual desorption amount is less than the estimated desorption amount (step S80). The actual desorption amount is the actual amount of CO2 desorbed from the target adsorbent since the desorption process started. The control unit 110 receives information from a temperature sensor, a pressure sensor, a flow rate sensor, and a CO2 concentration sensor (not shown) that are provided in the piping that forms the raw material gas flow path 80. The actual desorption amount is calculated from a relational expression, map, etc. prepared in advance using the above. The expected desorption amount is the amount of CO2 desorption that is expected to be desorbed from the target adsorbent after the desorption process is started, and is set for each elapsed time after the start of the desorption process. The control unit 110 functions as a desorption amount acquisition unit, thereby acquiring the expected desorption amount corresponding to the elapsed time after the start of the desorption process from a memory unit (not shown), and determining whether the actual desorption amount is less than the expected desorption amount. If the actual desorption amount is greater than the expected desorption amount (step S80: NO), the control unit 110 executes the process of step S70 again.

[0046] If the actual desorption amount is less than the expected desorption amount (step S80: YES), the control unit 110 corrects the switching timing Tthr (step S90). Specifically, the control unit 110 corrects the switching timing Tthr so ​​that the parallel period is shorter than the switching timing Tthr initially acquired in step S50. In this way, the control unit 110 corrects the length of the parallel period corresponding to the CO2 treatment amount Ga and the length of the opposing period (the initially acquired switching timing Tthr) according to the actual desorption amount. Thereafter, the control unit 110 uses the corrected switching timing Tthr to determine whether the desorption process elapsed period T has passed the switching timing Tthr (step S70).

[0047] As described above, according to the gas adsorption device 1 of the first embodiment, the flow direction of the heat medium in the desorption process is set to a flow direction corresponding to the amount of CO2 entering and leaving the adsorber from the start of the adsorption process to the end of the desorption process. As described above, when the load is relatively low, that is, when the amount of CO2 being processed is relatively small, the recovery rate of the adsorbed gas is the same regardless of whether the heat medium is flowed in the parallel or countercurrent direction in the desorption process (see FIG. 4). However, flowing in the parallel direction reduces the possibility of impurities being mixed into the recovered gas recovered from the adsorbent (see FIG. 5). On the other hand, when the load is relatively high, that is, when the amount of CO2 being processed is relatively large, flowing the heat medium in the countercurrent direction in the desorption process can increase the CO2 recovery rate (see FIG. 4). Therefore, compared to a configuration in which the flow direction of the heat medium in the desorption process is constant regardless of the amount of CO2 being processed, this configuration allows the flow direction of the heat medium in the desorption process to be changed between the parallel direction and the countercurrent direction depending on the amount of CO2 being processed, thereby allowing the heat medium to flow in a flow direction appropriate to the amount of CO2 being processed. Specifically, in the gas adsorption device 1 of the first embodiment, the flow direction of the heat transfer medium in the desorption process is parallel at low loads (up to 0.6), counter at high loads (1.0), and then switches from parallel to counter at medium loads (less than 0.6 to 1.0) (see Figure 6).

[0048] Furthermore, in the gas adsorption device 1 of the first embodiment, when the CO2 treatment amount is a medium load, the flow direction of the heat transfer medium in the desorption process is first switched to one of the parallel direction and the counter-current direction, and then to the other direction. When the heat transfer medium is circulated in the parallel direction, the amount of CO2 desorbed from the adsorbent is smaller than when the heat transfer medium is circulated in the counter-current direction, thereby reducing the unadsorbed portion in the adsorbent after the desorption process (see FIG. 5). As a result, the unadsorbed portion is further reduced after the subsequent adsorption process, thereby reducing the possibility of impurities being mixed into the recovered gas recovered from the adsorbent. However, on the other hand, the CO2 capture rate decreases as the load increases (see FIG. 4). On the other hand, when the heat transfer medium is circulated in the counter-current direction, the amount of CO2 desorbed from the adsorbent is greater than when the heat transfer medium is circulated in the parallel direction, thereby increasing the CO2 capture rate (see FIG. 4). However, on the other hand, the unadsorbed portion in the adsorbent after the desorption process is larger, and it is likely that a large amount of unadsorbed portion will remain even after the subsequent adsorption process, thereby increasing the possibility of impurities being mixed into the recovered gas recovered from the adsorbent (see FIG. 5). In this regard, according to the gas adsorption device 1 of the first embodiment, by switching the flow direction of the heat transfer medium during the desorption process from one of the parallel direction and the opposing direction to the other, it is possible to simultaneously reduce the unadsorbed portion in the adsorbent after the desorption process and increase the CO2 recovery rate during the desorption process.

[0049] Regarding the switching of the flow direction in the gas adsorption device 1 of the first embodiment, specifically, when the CO2 processing amount is a medium load, the flow direction of the heat transfer medium in the desorption process is switched from the parallel direction to the counter direction. That is, first, the heat transfer medium is circulated in the parallel direction, which reduces the unadsorbed portion in the adsorbent, and then the heat transfer medium is circulated in the counter direction, which increases the amount of CO2 desorbed from the adsorbent, thereby achieving both of the above.

[0050] Furthermore, in the gas adsorption device 1 of the first embodiment, when switching the flow direction at a medium load, the smaller the amount of CO2 processed (the lower the load), the longer the parallel period, and the larger the amount of CO2 processed (the higher the load), the longer the counter period. Therefore, since the parallel period and the counter period can be adjusted according to the amount of CO2 processed (load), it is possible to more accurately reduce the unadsorbed portion in the adsorbent after the desorption step and increase the recovery rate of the adsorbed gas in the desorption step.

[0051] Furthermore, in the gas adsorption device 1 of the first embodiment, the switching timing Tthr obtained according to the CO2 processing amount is corrected according to the actual desorption amount. Therefore, if the CO2 desorption amount during the initial parallel period of the desorption process is smaller than expected, the parallel period can be shortened and the counter period can be lengthened.

[0052] Second Embodiment The gas adsorption device of the second embodiment is the same as the gas adsorption device 1 of the first embodiment except that, compared to the gas adsorption device 1 of the first embodiment, at a medium load (less than 0.6 to 1.0), the flow direction of the heat transfer medium in the desorption process is switched from an opposing direction to a parallel direction.

[0053] The flow direction adjustment process in the second embodiment differs from the first embodiment in the processing of steps S50, 60, 80, 90, and 100 (the processing of steps S10 to S40 and 70 is the same). In the flow direction adjustment process in the second embodiment, first, the switching timing Tthr acquired in step S50 is the timing when the desorption process is started, the heat medium first flows in the opposing direction, and then the heat medium flows in the parallel direction. Note that this switching timing Tthr is also set so that the parallel period becomes longer as the CO2 processing amount (load) decreases. Furthermore, in step S60, the flow direction of the heat medium in the target adsorber is set to the opposing direction, and in step S100, the flow direction of the heat medium in the target adsorber is set to the parallel direction. Furthermore, in step S80, it is determined whether the actual desorption amount is greater than the expected desorption amount. If the actual desorption amount is greater than the estimated desorption amount, the switching timing Tthr is corrected in step S90 so that the opposing period is shorter than the switching timing Tthr initially acquired in step S50.

[0054] As with the first embodiment, the gas adsorption device of the second embodiment described above allows the heat transfer medium to flow in an appropriate flow direction according to the amount of CO2 to be processed. Furthermore, it is possible to simultaneously reduce the unadsorbed portion of the adsorbent after the desorption process and increase the CO2 recovery rate in the desorption process. Furthermore, with the gas adsorption device of the second embodiment, if the amount of CO2 desorbed during the initial opposing period of the desorption process is greater than expected, the opposing period can be shortened and the parallel period can be lengthened.

[0055] <Modification of this embodiment> The present invention is not limited to the above-described embodiment, and can be embodied in various forms without departing from the spirit of the invention. For example, the following modifications are also possible.

[0056] [Variation 1] In the above embodiment, carbon dioxide (CO2) is used as the specific adsorbed gas, but this is not limiting. For example, the specific adsorbed gas may be water (H2O), nitrogen oxides (NO2), or the like. X ), sulfur oxidation SO X ) etc.

[0057] [Variation 2] In the above embodiment, the hydrogen supply source 60 is a water electrolysis device, but is not limited to this. For example, the hydrogen supply source 60 may be a gas tank that stores hydrogen gas.

[0058] [Variation 3] In the above embodiment, the flow direction of the heat medium in the desorption process is the parallel direction at low load, the opposing direction at high load, and the parallel direction or the opposing direction at medium load, and then switched to the other direction. However, this is not limited to this. For example, the flow direction may be switched at low load and high load. In this case, at low load, the parallel period is used for most of the desorption process, and the opposing period is used for the remaining period. At high load, the opposing period is used for most of the desorption process, and the parallel period is used for the remaining period.

[0059] [Variation 4] In the first embodiment, the switching timing Tthr is corrected during the desorption process according to the actual desorption amount after the first parallel period starts in the desorption process (step S60), but this is not limited to this. For example, the switching timing Tthr may not be corrected during the desorption process, but may be corrected during a period other than the desorption process (such as the adsorption process or the cooling process), and the corrected switching timing Tthr may be used for the subsequent desorption process. The actual desorption amount used for this correction may be the actual desorption amount calculated in the immediately preceding desorption process, or may be a plurality of actual desorption amounts accumulated by repeating the desorption process.

[0060] This aspect has been described above based on embodiments and modifications. However, the above-described embodiments are intended to facilitate understanding of this aspect and are not intended to limit this aspect. This aspect may be modified or improved without departing from the spirit and scope of the claims, and equivalents thereof are included in this aspect. Furthermore, if a technical feature is not described as essential in this specification, it may be deleted as appropriate. [Explanation of symbols]

[0061] 1...Gas adsorption device 10...First adsorption device 12...First adsorbent 20…Second adsorption device 22…Second adsorbent 30…Third adsorption device 32...Third adsorbent 40...Combustion equipment 50...Exhaust gas supply passage 51...First exhaust gas supply valve 52...Second exhaust gas supply valve 53...Third exhaust gas supply valve 54...First discharge flow path 55...Second discharge flow path 56...Third discharge flow path 57...First exhaust valve 58...Second exhaust valve 59...Third exhaust valve 60...Hydrogen source 70...Hydrogen supply channel 71...First hydrogen supply valve 72...Second hydrogen supply valve 73...Third hydrogen supply valve 74...Fourth hydrogen supply valve 80...raw material gas flow path 81...First raw material gas supply valve 82...Second raw material gas supply valve 83...Third source gas supply valve 85...Vacuum pump 90...Hydrocarbon synthesis unit 100...heat medium flow path 101...First flow path 102...Second flow path 103...Third flow path 104...First flow path switching valve 105...Second flow path switching valve 106...Third flow path switching valve 107...Fourth flow path switching valve 108...Pump 109…Temperature adjustment section 110...Control unit

Claims

1. 1. A gas adsorption apparatus comprising: an adsorber containing an adsorbent that adsorbs a specific adsorbed gas contained in the mixed gas; a purge gas supply unit that supplies a purge gas into the adsorber; a heat medium flow path forming portion that forms a heat medium flow path through which a heat medium that exchanges heat with the adsorbent flows; a heat medium delivery unit that allows the heat medium to flow through the heat medium flow path and is capable of changing the flow direction of the heat medium; a control unit that controls the gas adsorption device, The control unit an adsorption step of adsorbing the adsorbed gas onto the adsorbent and a desorption step of supplying the purge gas into the adsorber to desorb the adsorbed gas from the adsorbent are repeatedly performed; a flow direction of the heat medium in the desorption step that corresponds to the processing amount of the adsorbed gas that flows in and out of the adsorber from the start of the adsorption step to the end of the desorption step.

2. 2. The gas adsorption device according to claim 1, the control unit sets the flow direction of the heat medium in the desorption step to one of a parallel direction that is the same direction as the flow direction of the purge gas inside the adsorber and a counter direction that is the opposite direction to the flow direction of the purge gas inside the adsorber, and then switches the flow direction to the other direction.

3. 3. The gas adsorption device according to claim 2, The control unit switches the flow direction of the heat medium in the desorption step from the parallel direction to the opposing direction.

4. The gas adsorption apparatus according to claim 2 or 3, The control unit the smaller the processing amount, the longer the parallel period during which the heat medium is circulated in the parallel direction in the desorption step; The gas adsorption device, wherein the opposing period during which the heat medium is circulated in the opposing directions in the desorption step is made longer as the processing amount increases.

5. The gas adsorption apparatus according to claim 4, further comprising: a desorption amount acquisition unit that acquires the amount of the adsorbed gas desorbed from the adsorbent, The control unit corrects the length of the parallel period and the length of the opposing period according to the processing amount, in accordance with the desorption amount.

6. 1. A gas adsorption method comprising: a purge gas supply step of supplying a purge gas into an adsorber containing an adsorbent that adsorbs a specific adsorbed gas contained in the mixed gas; a heat medium sending step of circulating the heat medium in a heat medium flow path through which the heat medium that exchanges heat with the adsorbent flows and changing the flow direction of the heat medium; a control step of controlling the purge gas supply step and the heat medium delivery step, In the control step, an adsorption step of adsorbing the adsorbed gas onto the adsorbent and a desorption step of desorbing the adsorbed gas from the adsorbent by carrying out the purge gas supply step, The flow direction of the heat medium in the heat medium sending step executed in the desorption step a flow direction corresponding to a processing amount of the adsorbed gas flowing in and out of the adsorber from the start of the adsorption step to the end of the desorption step.

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