JP2022097832A - Gas separation system, and hydrocarbon manufacturing system - Google Patents

Abstract

To provide a technique for improving efficiency of carbon dioxide desorption by purge gas in a gas separation system.SOLUTION: A gas separation system comprises: connection flow passages that can connect a first adsorber and a second adsorber in series among a plurality of adsorbers; a purge gas supply flow passage that can supply a purge gas to the first adsorber; and a control unit that can simultaneously execute a first desorption step of causing the purge gas to be supplied to the first adsorber through the purge gas supply flow passage in a state where carbon dioxide is adsorbed on the first and second adsorbers, so as to desorb the carbon dioxide from the first adsorber, and a second desorption step of causing the first adsorber to connect with the second adsorber through the connection passages, causing the purge gas circulating in the first adsorber to flow into the second adsorber through the connection flow passages, so as to desorb the carbon dioxide from the second adsorber.SELECTED DRAWING: Figure 1

Description

The present invention relates to a gas separation system that separates carbon dioxide from a carbon dioxide-containing gas.

Conventionally, in a methane production device that produces methane from carbon dioxide and hydrogen, two adsorption towers that accommodate an adsorbent having carbon dioxide adsorption performance are provided, and each adsorption tower repeatedly adsorbs and desorbs carbon dioxide. A technique has been proposed in which carbon dioxide is separated from a carbon dioxide-containing gas, and methane is produced using the separated carbon dioxide and hydrogen used at the time of separation (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2019-142806

According to the technique described in Patent Document 1, hydrogen is used to purge the inside of the adsorption tower to desorb carbon dioxide, and then hydrogen used in the purge is used to generate methane, which is used for purging. The amount of hydrogen is limited. Therefore, it may not be possible to sufficiently obtain the desorption efficiency of carbon dioxide from the adsorption tower by the purge gas. Such a problem is a problem common not only to methane production equipment that uses hydrogen as a purge gas but also to a carbon dioxide separation system that separates carbon dioxide using an adsorbent.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a technique for improving the efficiency of carbon dioxide desorption by a purge gas in a gas separation system.

The present invention has been made to solve at least a part of the above-mentioned problems, and can be realized as the following forms.

(1) According to one embodiment of the present invention, there is provided a gas separation system including a plurality of adsorbers that internally contain an adsorbent capable of adsorbing carbon dioxide. This gas separation system includes a connection flow path capable of connecting the first adsorbent and the second adsorber in series among the plurality of adsorbers, and a purge gas supply flow path capable of supplying purge gas to the first adsorber. Then, with carbon dioxide adsorbed on the first adsorber and the second adsorber, the purge gas is supplied to the first adsorber via the purge gas supply flow path, and the purge gas is supplied from the first adsorber. The first desorption step of desorbing carbon dioxide and the purge gas flowing through the first adsorber by connecting the second adsorber to the first adsorber via the connection flow path are passed through the connecting flow. A control unit capable of simultaneously executing a second desorption step of flowing into the second adsorber through a path and desorbing carbon dioxide from the second adsorber is provided.

According to this configuration, since the purge gas that has passed through the first adsorber can flow into the adsorber, the second adsorber can also be desorbed at the same time. The mixed gas containing the purge gas from which carbon dioxide has been desorbed in the first adsorber has a high carbon dioxide concentration immediately after the start of the desorption step, but the carbon dioxide concentration gradually decreases thereafter. When this mixed gas flows into the second adsorber, the carbon dioxide in the second adsorber can also be desorbed. Therefore, the efficiency of carbon dioxide desorption by the purge gas can be improved.

(2) A carbon dioxide-containing gas in the above-described gas separation system capable of supplying a carbon dioxide-containing gas containing carbon dioxide to a third adsorbent different from the first adsorber and the second adsorber. The control unit further includes a supply flow path, and the control unit supplies the carbon dioxide-containing gas to the third adsorber via the carbon dioxide-containing gas supply flow path to adsorb the carbon dioxide. The first desorption step, the second desorption step, and the adsorption / desorption step including the adsorption step, which can be executed at the same time as the first desorption step and are simultaneously executed, are the first desorption step and the first desorption step. 2. The first adsorber, the second adsorber, and the third adsorber in which each of the desorption step and the adsorption step is executed may be changed and repeatedly executed.

According to this configuration, carbon dioxide-containing gas is supplied to the third adsorber, and carbon dioxide adsorbed in the first adsorber and the second adsorber while the carbon dioxide is adsorbed by the third adsorber. Carbon can be desorbed. That is, since the desorption step of the first adsorbent and the second adsorber is performed during the time of the adsorption step, it is possible to increase the amount of purge gas in a pseudo manner and lengthen the desorption time. As a result, a limited amount of purge gas can improve the efficiency of carbon dioxide desorption in a limited time.

(3) In the gas separation system of the above embodiment, the control unit transfers the purge gas flowing through the first adsorber through the connection flow path during a part of the second desorption step. It may flow into the second adsorber. By doing so, for example, it is expected that the carbon dioxide concentration of the mixed gas discharged from the first adsorber is low, and the carbon dioxide of the second adsorber is sufficiently desorbed by the purge gas circulating in the first adsorber. Only during this period, the purge gas that has flowed through the first adsorber can be appropriately reused, such as by flowing the purge gas into the second adsorber.

(4) In the gas separation system of the above embodiment, the purge gas may be hydrogen. In this way, for example, a hydrocarbon can be produced by using hydrogen as a purge gas discharged from the adsorber and desorbed carbon dioxide. By doing so, the purity of the hydrocarbon can be improved as compared with the case of using other purge gas.

(5) According to another embodiment of the present invention, a hydrocarbon production system is provided. This hydrocarbon production system uses a mixed gas of the gas separation system of the above embodiment, carbon dioxide separated by the gas separation system connected to the gas separation system, and hydrogen used as the purge gas. It includes a hydrocarbon generation unit that produces a hydrocarbon compound. According to this configuration, the hydrocarbon generation unit can generate a hydrocarbon compound by using a mixed gas having a high concentration of carbon dioxide and hydrogen. This makes it possible to produce a highly pure hydrocarbon compound. Further, in the gas separation system, since the desorption efficiency of carbon dioxide by the purge gas is improved by reusing the purge gas, the hydrocarbon generation efficiency in the hydrocarbon generation unit can be improved. In addition, the amount of surplus hydrogen in the production of methane in the hydrocarbon generation unit can be reduced.

The present invention can be realized in various aspects, for example, a gas separation method, a hydrogen production method, a gas separation system control method, a hydrocarbon production system control method, and a computer for controlling these methods. A computer program to be executed by a computer, a server device for distributing the computer program, a non-temporary storage medium for storing the computer program, a carbon dioxide circulation system, a fuel production system using hydrogen as fuel, etc. be able to.

It is explanatory drawing which shows the schematic structure of the gas separation system of 1st Embodiment. It is explanatory drawing of the switching timing of the adsorber in a gas separation system. It is explanatory drawing of the process 1 in a gas separation system. It is explanatory drawing of the process 2 in a gas separation system. It is explanatory drawing of the process 3 in a gas separation system. It is explanatory drawing which conceptually shows the adsorption amount of carbon dioxide at the start of process 1 to process 3. It is explanatory drawing which shows the schematic structure of the gas separation system of the comparative example. It is explanatory drawing of the switching timing of the adsorber in the gas separation system of the comparative example. It is a figure which shows the change of the carbon dioxide adsorption amount in the desorption step of the gas separation system of 1st Embodiment. It is a figure which shows the change of the carbon dioxide adsorption amount in the desorption process of the gas separation system of the comparative example. It is explanatory drawing which shows the schematic structure of the gas separation system of 2nd Embodiment. It is explanatory drawing of the switching timing of the adsorber in the gas separation system of 2nd Embodiment. It is explanatory drawing of the process 1A in the gas separation system of 2nd Embodiment. It is explanatory drawing of the switching timing of the adsorber in the gas separation system of 3rd Embodiment. It is explanatory drawing of the 2nd desorption step of the process 1B of 3rd Embodiment. It is explanatory drawing which shows the schematic structure of the gas separation system of 4th Embodiment. It is explanatory drawing of the switching timing of the adsorber in the gas separation system of 4th Embodiment. It is explanatory drawing of the 2nd desorption step of the process 1C of 4th Embodiment. It is explanatory drawing which shows the schematic structure of the hydrocarbon production system of 5th Embodiment.

<First Embodiment>
FIG. 1 is an explanatory diagram showing a schematic configuration of the gas separation system 1 of the first embodiment. The gas separation system 1 separates and recovers carbon dioxide contained in exhaust gas discharged from a combustion furnace, an internal combustion engine, or the like. The gas separation system 1 includes a plurality of adsorbers 11, 12, 13 (also simply referred to as an adsorber 10 when the adsorbers 11, 12, 13 are not distinguished), a carbon dioxide-containing gas supply flow path 20, and a purge gas. A purge gas supply flow path 70 that supplies hydrogen as a fuel, a connection flow path 80 (connection flow path 81, connection flow path 82, and connection flow path 83) that connects two adsorbers 10 in series, and a heat medium flow path. 30, a mixed gas flow path 60, a surge tank 40, and a control unit 55 are provided.

The plurality of adsorbers 11, 12, and 13 are formed in a cylindrical shape, and the adsorbents 11a, 12a, and 13a are housed therein. The adsorbents 11a, 12a, and 13a are materials having carbon dioxide occlusion performance, such as zeolite, activated carbon, and silica gel. A carbon dioxide-containing gas supply flow path 20, a purge gas supply flow path 70, a mixed gas flow path 60, and a heat medium flow path 30 are connected to each of the adsorbers 11, 12, and 13. Refrigerant flow paths (not shown) are also formed in each of the plurality of adsorbers 11, 12, and 13.

The carbon dioxide-containing gas supply flow path 20 is connected to an external exhaust gas supply device (for example, a combustion furnace, an internal combustion engine, etc.) that discharges exhaust gas as carbon dioxide-containing gas, and the exhaust gas discharged by the exhaust gas supply device flows. .. The exhaust gas flowing through the carbon dioxide-containing gas supply channel 20 is supplied to the adsorbers 11, 12, and 13 via the exhaust gas branch channels 21, 22, and 23. Exhaust gas inlet valves 21a, 22a, 23a are provided in the exhaust gas branch channels 21, 22, and 23, respectively. Each of the exhaust gas inlet valves 21a, 22a, and 23a controls the supply of exhaust gas to the inside of the adsorbers 11, 12, and 13 in response to a command from the control unit 55. In the present embodiment, the exhaust gas is exemplified as the carbon dioxide-containing gas, but the carbon dioxide-containing gas does not have to be the exhaust gas.

As shown in FIG. 1, the mixed gas flow path 60 is connected to each of the adsorbers 11, 12, and 13 via the mixed gas distribution flow paths 61, 62, and 63. A mixed gas containing carbon dioxide desorbed from the adsorbents 11a, 12a, 13a and hydrogen as a purge gas flows in the mixed gas flow path 60. The mixed gas may contain, for example, nitrogen, oxygen and the like. The mixed gas distribution channels 61, 62, 63 are provided with mixed gas outlet valves 61a, 62a, 63a. Each of the mixed gas outlet valves 61a, 62a, 63a controls the flow of the mixed gas from the adsorbents 11, 12, and 13 in response to a command from the control unit 55.

The purge gas supply flow path 70 supplies purge gas to the inside of the adsorbers 11, 12, and 13. In the purge gas supply flow path 70 connected to the external purge gas supply unit (for example, a hydrogen tank), the flow rate controller 70a adjusts the flow rate of hydrogen flowing through the purge gas supply flow path 70 in response to a command from the control unit 55. Is provided. Hydrogen flowing through the purge gas supply flow path 70 is supplied to the adsorbers 11, 12, and 13 via the purge gas distribution channels 71, 72, and 73. Purge gas inlet valves 71a, 72a, 73a are provided in the purge gas distribution channels 71, 72, and 73, respectively. Each of the purge gas inlet valves 71a, 72a, 73a controls the flow of hydrogen into the adsorbers 11, 12, and 13 in response to a command from the control unit 55.

The connection flow path 80 connects two adsorbers 10 in series, and supplies a mixed gas (mixed gas containing purge gas and carbon dioxide) discharged from one adsorber 10 to the other adsorber 10. Specifically, the connection flow path 81 connects the mixed gas branch flow path 61 and the purge gas branch flow path 72, and connects the adsorber 11 and the adsorber 12 in series. The connection flow path 82 connects the mixed gas branch flow path 62 and the purge gas branch flow path 73, and connects the adsorber 12 and the adsorber 13 in series. The connection flow path 83 connects the mixed gas branch flow path 63 and the purge gas branch flow path 71, and connects the adsorber 13 and the adsorber 11 in series. That is, the connection flow path 80 is a bypass flow path. The connection flow path 81, 82, and 83 are provided with connection flow path valves 81a, 82a, and 83a, respectively. Each of the connection flow path valves 81a, 82a, and 83a controls the gas flow in the connection flow path 80 in response to a command from the control unit 55.

The heat medium flow path 30 is connected to a heat medium tank (not shown), and the heat medium flows in the heat medium flow path 30. The heat medium flowing through the heat medium flow path 30 is supplied to the adsorbers 11, 12, and 13 via the heat medium distribution flow paths 31, 32, 33. As a result, heat is transferred to the adsorbents 11, 12, and 13 by the heat medium. The heat medium flow path 30 is provided with a heater 30a for heating the heat medium, and the temperature of the heat medium is controlled by the control unit 55 controlling the heater 30a. In this embodiment, oil is used as a heat medium, but in other embodiments, water, steam, gas, or the like may be used.

The heat medium distribution channels 31, 32, 33 are provided with heat medium inlet valves 31a, 32a, 33a. Each of the heat medium inlet valves 31a, 32a, 33a controls the flow of the heat medium to the adsorbents 11, 12, and 13 in response to a command from the control unit 55. The adsorbers 11, 12, and 13 in the present embodiment are double-shell tanks (double tubes), and the heat medium flows into the gap between the outer shell and the inner shell. As a result, heat is transferred into the adsorbers 11, 12, and 13 by the heat medium. In another embodiment, for example, the heat medium distribution channels 31, 32, 33 may be wound around the outer circumferences of the adsorbers 11, 12, 13, respectively. Even in this way, heat can be input into the adsorbents 11, 12, and 13 by the heat medium. In another embodiment, the adsorber 10 may be heated by using a heater provided in the adsorber 10 (for example, heating wire, warm air, light irradiation, etc.).

A mixed gas flow path 60 is connected to the surge tank 40. The surge tank 40 stores the mixed gas flowing through the mixed gas flow path 60.

The control unit 55 is a computer including a ROM, a RAM, and a CPU, and is a gas separation system 1 such as switching of the adsorbers 11, 12, and 13 in the gas separation process described later, and valve open / close control. Take control of the whole. The details of the control contents of the control unit 55 will be described later.

The program for realizing the gas separation process described above may be stored in advance in the control unit 55. Further, the program may be provided from the program provider side via a communication network. Further, the program may be stored in a portable storage medium that is commercially available and distributed. In this case, the portable storage medium may be set in an external or built-in reader, and the program may be read and executed by the control unit 55. As the portable storage medium, various types of storage media such as a CD-ROM, a DVD-ROM, a flexible disk, an optical disk, a magneto-optical disk, an IC card, and a USB memory device can be used. The program stored in such a storage medium is read by the reader.

FIG. 2 is an explanatory diagram of switching timing of the adsorber 10 in the gas separation system 1 of the present embodiment. In the gas separation process of the present embodiment, as shown in the figure, step 1, step 2, and step 3 are set as one cycle, and this cycle is repeated a plurality of times. In each step, the adsorption step, the second desorption step (heating + desorption), and the first desorption step are each performed in any of the three adsorbers 11, 12, and 13. Specifically, in step 1, the adsorption step is executed in the adsorber 13, the first desorption step is executed in the adsorber 11, and the second desorption step is executed in the adsorber 12. In step 2, the adsorption step is executed in the adsorber 11, the first desorption step is executed in the adsorber 12, and the second desorption step is executed in the adsorber 13. In step 3, the adsorber 12 executes the adsorption step, the adsorber 13 executes the first desorption step, and the adsorber 11 executes the second desorption step. In the gas separation system 1 of the present embodiment, in this way, carbon dioxide in the exhaust gas is adsorbed in one of the adsorbers, and at the same time, the adsorbed carbon dioxide is desorbed in the other two adsorbers. This makes it possible to constantly supply carbon dioxide-containing gas (exhaust gas). Each of steps 1, 2 and 3 in this embodiment is also referred to as a "suction / desorption step".

Focusing on one adsorber 10, the adsorption step, the second desorption step, and the first desorption step are repeated in this order. Hereinafter, the adsorber 13 will be described as an example. In the adsorption step, the exhaust gas as a carbon dioxide-containing gas is supplied to the adsorber 13, and the refrigerant is also supplied. By cooling the adsorber 13, carbon dioxide in the exhaust gas is adsorbed on the adsorbent 13a. After a predetermined adsorption time elapses, the process proceeds to the second desorption step. In the present embodiment, the adsorption time is set to the time required for the full amount of carbon dioxide to be adsorbed on the adsorbent 13a of the adsorber 13. The adsorption time can be obtained by experiment, calculation, simulation, or the like. In the gas separation process of the present embodiment, the length of each step is set to the same adsorption time.

In the second desorption step, a heat medium is supplied to the adsorber 13 and hydrogen as a purge gas is supplied. When the heat medium is supplied to the adsorber 13 and the temperature of the adsorbent 13a is raised, the carbon dioxide trapped in the adsorbent 13a is easily desorbed from the adsorbent 13a. In the second desorption step, a mixed gas containing carbon dioxide and a purge gas (hydrogen in the present embodiment) discharged from the adsorber 12 (step 2 in FIG. 2) in which the first desorption step is performed is an adsorber. It is supplied to 13. That is, the purge gas is supplied through the connection flow path 82 (FIG. 1). When the mixed gas containing the purge gas is supplied to the adsorber 13, the partial pressure of carbon dioxide inside the adsorber 13 decreases, so that the carbon dioxide adsorbed on the adsorbent 13a is desorbed from the adsorbent 13a. After the adsorption time elapses, the process proceeds to the first desorption step.

In the first desorption step, the purge gas is supplied to the adsorber 13 via the purge gas supply flow path 70. That is, in the first desorption step, purge gas is supplied from an external purge gas supply unit (for example, a hydrogen tank). Since the adsorber 13 is heated in the second desorption step (FIG. 2), carbon dioxide is easily desorbed from the adsorbent 13a. When the purge gas is supplied to the adsorber 13, the partial pressure of carbon dioxide inside the adsorber 13 decreases, so that the carbon dioxide adsorbed on the adsorbent 13a is desorbed from the adsorbent 13a. After the adsorption time elapses, the process returns to the adsorption step.

FIG. 3 is an explanatory diagram of step 1 in the gas separation system 1, FIG. 4 is an explanatory diagram of step 2 in the gas separation system 1, and FIG. 5 is an explanatory diagram of process 3 in the gas separation system 1. .. In the gas separation system 1, carbon dioxide is separated from the exhaust gas by sequentially supplying the exhaust gas (carbon dioxide-containing gas) to each of the three adsorbers 11, 12, and 13. In the gas separation system 1, two adsorbers 10 are connected in series via a connecting flow path 80. Then, the purge gas that has flowed through the adsorber 10 on which the first desorption step is executed is supplied to the adsorber 10 on which the second desorption step is executed. Here, in the adsorber 10 in the second desorption step, a heat medium is supplied and heated, and a purge gas (mixed gas) is supplied. In FIGS. 3 to 5, the flows of exhaust gas, heat medium, and purge gas (hydrogen) are shown by thick solid lines.

As shown in FIG. 3, in step 1 (FIG. 2), the adsorption step is performed by the adsorber 13, and the exhaust gas is supplied to the adsorber 13. Specifically, the exhaust gas inlet valve 23a is opened by the control unit 55, the exhaust gas inlet valve 21a and the exhaust gas inlet valve 22a are closed, and the exhaust gas inlet valve 21a and the exhaust gas inlet valve 22a are closed via the carbon dioxide-containing gas supply flow path 20 and the exhaust gas branch flow path 23. , Exhaust gas is supplied to the adsorber 13. In the adsorber 13, carbon dioxide contained in the exhaust gas is trapped by the adsorbent 13a, and most of the gas such as nitrogen and water that is not trapped by the adsorbent 13a is treated as off gas outside the gas separation system 1, for example. Released into the atmosphere.

The first desorption step is performed on the adsorber 11, and the purge gas is supplied to the adsorber 11. Specifically, the purge gas inlet valve 71a is opened by the control unit 55, the purge gas inlet valve 72a and the purge gas inlet valve 73a are closed, and the adsorber is closed via the purge gas supply flow path 70 and the purge gas branch flow path 71. Purge gas is supplied to 11. When the purge gas is supplied in the adsorber 11, the carbon dioxide adsorbed on the adsorbent 11a is desorbed from the adsorbent 11a. The carbon dioxide desorbed from the adsorbent 11a is mixed with the purge gas (hydrogen) inside the adsorber 11. In step 1, since the mixed gas outlet valve 61a is closed and the connection flow path valve 81a is opened, the mixed gas discharged from the adsorber 11 is the mixed gas branch flow path 61 and the connection flow path 81. , And flows into the adsorber 12 through the purge gas distribution channel 72.

The second desorption step is performed on the adsorber 12, and the heat medium and the above-mentioned mixed gas are supplied to the adsorber 12. Specifically, the control unit 55 controls the heater 30a so that the heat medium reaches a predetermined temperature (heat input amount), and the heat medium inlet valve 32a is opened. As a result, the heat medium flowing through the heat medium flow path 30 is supplied to the adsorber 12 via the heat medium distribution flow path 32. When the heat medium is supplied and the mixed gas containing the purge gas is supplied in the adsorber 12, the carbon dioxide adsorbed on the adsorbent 12a is desorbed from the adsorbent 12a. The carbon dioxide desorbed from the adsorbent 12a is mixed with the mixed gas including the purge gas inside the adsorber 12. Since the mixed gas outlet valve 62a is opened in step 1, the mixed gas discharged from the adsorber 12 is stored in the surge tank 40 through the mixed gas distribution flow path 62 and the mixed gas flow path 60. The adsorber 10 on which the first desorption step is performed is the "first adsorber", the adsorber 10 on which the second desorption step is performed is the "second adsorber", and the adsorber 10 on which the adsorption step is performed is the "third". When referred to as an "adsorber", in step 1, the adsorber 11 is a "first adsorber", the adsorber 12 is a "second adsorber", and the adsorber 13 is a "third adsorber".

As shown in FIG. 4, in step 2, an adsorption step is performed by the adsorber 11, and the exhaust gas is supplied to the adsorber 11 via the carbon dioxide-containing gas supply flow path 20 and the exhaust gas branch flow path 21. The first desorption step is performed on the adsorber 12, and the purge gas is supplied to the adsorber 12 via the purge gas supply flow path 70 and the purge gas distribution flow path 72. The second desorption step is performed on the adsorber 13, and carbon dioxide and purge gas discharged from the adsorber 12 are supplied to the adsorber 13 via the mixed gas flow path 62, the connection flow path 82, and the purge gas branch flow path 73. The mixed gas containing is supplied. The mixed gas discharged from the adsorber 13 is stored in the surge tank 40 through the mixed gas distribution channel 63 and the mixed gas flow path 60. In step 2, the adsorber 11 is a "third adsorber", the adsorber 12 is a "first adsorber", and the adsorber 13 is a "second adsorber".

As shown in FIG. 5, in step 3, an adsorption step is performed by the adsorber 12, and the exhaust gas is supplied to the adsorber 12 via the carbon dioxide-containing gas supply flow path 20 and the exhaust gas branch flow path 22. The first desorption step is performed on the adsorber 13, and the purge gas is supplied to the adsorber 13 via the purge gas supply flow path 70 and the purge gas distribution flow path 73. The second desorption step is performed on the adsorber 11, and the adsorber 11 has carbon dioxide and purge gas discharged from the adsorber 13 via the mixed gas branch flow path 63, the connection flow path 83, and the purge gas branch flow path 71. A mixed gas containing is supplied. The mixed gas discharged from the adsorber 11 is stored in the surge tank 40 through the mixed gas distribution channel 61 and the mixed gas flow path 60. In step 3, the adsorber 11 is the "second adsorber", the adsorber 12 is the "third adsorber", and the adsorber 13 is the "first adsorber". That is, in the gas separation system 1 of the present embodiment, the control unit 55 repeatedly executes the suction / desorption step by changing the first adsorber, the second adsorber, and the third adsorber.

FIG. 6 is an explanatory diagram conceptually showing the amount of carbon dioxide adsorbed at the start of steps 1 to 3. In FIG. 6, the amount of carbon dioxide adsorbed is shown with dot hatching. In FIG. 6, if the adsorber 10 is hatched as a whole, it indicates that the amount of carbon dioxide adsorbed is 100%, and if the adsorber 10 is not hatched, the amount of carbon dioxide adsorbed is 100%. Indicates 0%. Here, 100% is the amount adsorbed by the adsorber 10 at the end of the adsorption process. As described above, in the gas separation system 1 of the present embodiment, paying attention to one adsorber 10, a plurality of cycles are repeated with the adsorption step → the second desorption step → the desorption step as one cycle (FIG. 2). FIG. 6 illustrates one cycle after a plurality of cycles have been performed.

As shown in FIG. 6A, at the start of step 1, carbon dioxide was not adsorbed on the adsorbent 13a of the adsorber 13 (the amount of carbon dioxide adsorbed was 0%), and the adsorbent 11a of the adsorber 11 Carbon dioxide is adsorbed on the adsorbent 12a of the adsorber 12. The amount of carbon dioxide adsorbed by the adsorber 12 is 100%, and the amount adsorbed by the adsorber 11 is smaller than that of the adsorber 12 (for example, about 10%). In the adsorber 11, the second desorption step is performed in the immediately preceding step 3, the adsorbent 11a is in a state of being heated in temperature, and a part of carbon dioxide is desorbed.

In step 1, the purge gas is supplied to the adsorber 11, and the carbon dioxide-containing gas is supplied to the adsorber 13. The adsorber 11 and the adsorber 12 are connected in series, and the purge gas circulating in the adsorber 11 and the mixed gas containing carbon dioxide desorbed from the adsorbent 11a in the adsorber 11 flow into the adsorber 12. do.

In step 1, all the carbon dioxide adsorbed on the adsorbent 11a of the adsorber 11 is desorbed, so that the amount of carbon dioxide adsorbed by the adsorber 11 is 0% at the start of step 2. That is, carbon dioxide is not adsorbed on the adsorber 11 (FIG. 6 (B)). Further, since the mixed gas supplied to the adsorber 12 in step 1 contains a purge gas and a part of carbon dioxide adsorbed on the adsorbent 12a of the adsorber 12 is desorbed in step 1, the step 2 At the start of the above, the amount of carbon dioxide adsorbed by the adsorber 12 is small (for example, about 10%) (FIG. 6 (B)). Further, in step 1, the carbon dioxide-containing gas is supplied to the adsorber 13, and carbon dioxide is adsorbed on the adsorbent 13a. Therefore, at the start of step 2, the amount of carbon dioxide adsorbed by the adsorber 13 is 100%. (FIG. 6 (B)).

As shown in FIG. 6B, in step 2, the purge gas is supplied to the adsorber 12, and the carbon dioxide-containing gas is supplied to the adsorber 11. The adsorber 12 and the adsorber 13 are connected in series, and the purge gas circulating in the adsorber 12 and the mixed gas containing carbon dioxide desorbed from the adsorbent 12a in the adsorber 12 flow into the adsorber 13. do.

In step 2, all of the remaining carbon dioxide adsorbed on the adsorbent 12a of the adsorber 12 is desorbed, so that the amount of carbon dioxide adsorbed by the adsorber 11 is 0% at the start of step 3. That is, carbon dioxide is not adsorbed on the adsorber 11 (FIG. 6 (C)). Further, since the mixed gas supplied to the adsorber 13 in step 2 contains a purge gas and a part of carbon dioxide adsorbed on the adsorbent 13a of the adsorber 13 is desorbed in step 2, the step 3 At the start of the above, the amount of carbon dioxide adsorbed by the adsorber 13 is small (for example, about 10%) (FIG. 6 (C)). Further, in the step 2, the carbon dioxide-containing gas is supplied to the adsorber 11, and the carbon dioxide is adsorbed on the adsorbent 11a. Therefore, at the start of the step 3, the amount of carbon dioxide adsorbed by the adsorber 11 is 100%. (FIG. 6 (C)).

In this way, by repeating steps 1, 2 and 3 as one cycle, the adsorption step → the second desorption step (heating + desorption) → the first desorption step is repeatedly performed in each adsorber 10. As described above, in the second desorption step (heating + desorption), most of the carbon dioxide adsorbed on the adsorber 10 can be desorbed, and the remaining carbon dioxide is desorbed by the subsequent first desorption step. Since it can be separated, all of the carbon dioxide adsorbed on each adsorbent can be desorbed.

As described above, in the gas separation system 1 of the present embodiment, two adsorbers 10 are connected in series, and a purge gas that circulates in one adsorber 10 to desorb carbon dioxide is used in the subsequent stage. The carbon dioxide in the adsorber 10 is desorbed. That is, since the purge gas is reused, the carbon dioxide desorption efficiency by the purge gas can be improved.

Next, the effect of this embodiment will be described in comparison with a comparative example.
FIG. 7 is an explanatory diagram showing a schematic configuration of the gas separation system 1P of the comparative example. The gas separation system 1P of the comparative example does not have the connection flow path 80 (connection flow paths 81, 82, 83) in the gas separation system 1 of the present embodiment. The gas separation system 1P has the same other configurations as the gas separation system 1 of the present embodiment. Hereinafter, the same configurations as those of the gas separation system 1 are designated by the same reference numerals, and the preceding description will be referred to.

FIG. 8 is an explanatory diagram of the switching timing of the adsorber 10 in the gas separation system 1P of the comparative example. In the gas separation treatment of the comparative example, as in the above embodiment, the step 1P, the step 2P, and the step 3P are set as one cycle, and this cycle is repeated a plurality of times. In each step performed in the gas separation system 1P of the comparative example, the adsorption step, the heating step, and the desorption step are each performed in any of the three adsorbers 11, 12, and 13. Specifically, in step 1P, the adsorption step is executed in the adsorber 13, the heating step is executed in the adsorber 12, and the desorption step is executed in the adsorber 11. In step 2P, the adsorption step is executed in the adsorber 11, the heating step is executed in the adsorber 13, and the desorption step is executed in the adsorber 12. In step 3P, the adsorption step is executed in the adsorber 12, the heating step is executed in the adsorber 11, and the desorption step is executed in the adsorber 13. In the gas separation system 1P of the comparative example, in this way, carbon dioxide in the carbon dioxide-containing gas (exhaust gas) is adsorbed by any one adsorber 10, and at the same time, the other adsorber 10 is heated and adsorbed. The temperature of the material is raised, and the adsorbed carbon dioxide is desorbed in another heated adsorber 10.

FIG. 9 is a diagram showing changes in the amount of carbon dioxide adsorbed in the desorption step of the gas separation system 1 of the present embodiment. FIG. 9 illustrates the amount of carbon dioxide adsorbed in the adsorber 11 (first desorption step) and the adsorber 12 (second desorption step) in the step 1 shown in FIG. In FIG. 9, the first desorption step is shown by a solid line, and the second desorption step is shown by a broken line. In this example, the time of one process is designed to be 2000 seconds. Since the adsorption step is performed in the previous step (step 3) of the adsorber 12, the adsorption amount at the start of step 1 shown in FIG. 9 is 100%. In the adsorber 11, the second desorption step (heating + desorption) is performed in the previous step (step 3), and about 90% is desorbed, so that the amount of carbon dioxide adsorbed is 10%. Degree. In this example, an amount of purge gas that reacts with a full amount of carbon dioxide in just proportion is flowed into the adsorber 11. The adsorber 11 and the adsorber 12 were connected in series, and the mixed gas discharged from the adsorber 11 was supplied to the adsorber 12 and discharged. As a result, as shown in the figure, the amount of carbon dioxide adsorbed by the adsorber 11 became almost 0, and the amount of carbon dioxide adsorbed by the adsorber 12 became about 10%.

In this way, all carbon dioxide is desorbed from the adsorber 12 by reusing the purge gas used for desorbing carbon dioxide in the adsorber 11 to desorb the carbon dioxide in the adsorber 12. Was made.

FIG. 10 is a diagram showing changes in the amount of carbon dioxide adsorbed in the desorption step of the gas separation system 1P of the comparative example. FIG. 10 illustrates the amount of carbon dioxide adsorbed by the adsorber 11 in step 1P shown in FIG. In this example as well, the time of one step is designed to be 2000 seconds as in the example shown in FIG. In the adsorber 11, the adsorption step is performed in step 2, and then the heating step is performed in step 3. The adsorbed amount at the start of step 1 shown in FIG. 10 is 100%, and carbon dioxide is removed. It is in a state where it is easy to separate. In this example, the amount of purge gas that reacts with the full amount of carbon dioxide in just proportion is flowed into the adsorber 11 in the time of one step (2000 seconds), and then the same amount in the time of one step (2000 seconds). Purge gas was flowed and discharged. As shown in the figure, the amount of carbon dioxide adsorbed by the adsorber 11 becomes 0% in 3500 seconds to 4000 seconds, but about 7% of carbon dioxide remains in 2000 seconds (at the end of one step). As described above, in the gas separation system 1P of the comparative example, since the steps 1 to 3 are sequentially executed in each adsorber 10, the time of the desorption step cannot be extended. Therefore, at the end of the desorption step, about 7% of carbon dioxide remains in the adsorber 10. To desorb all carbon dioxide in the desorption step without changing the time of one step, for example, increase the energy for heating the adsorber 10 from the outside, connect the outlet of the adsorber 10 to a vacuum pump, etc. In addition, external energy must be input to accelerate desorption.

As described above, according to the gas separation system 1 of the present embodiment, the purge gas that has passed through one adsorber 10 can be reused and flowed into another adsorber 10, so that the two adsorbers can be used. 10 can be detached at the same time. The mixed gas containing purge gas and carbon dioxide discharged by desorbing carbon dioxide in the first adsorber 10 has a high carbon dioxide concentration immediately after the start of the desorption process, but the carbon dioxide concentration gradually increases thereafter. Go down. When this mixed gas flows into the second adsorber 10, the carbon dioxide in the second adsorber 10 can also be desorbed. Focusing on one adsorber 10, it is possible to increase the amount of purge gas in a pseudo manner and prolong the desorption time by desorbing carbon dioxide in the two steps of the second desorption step and the first desorption step. did it. In the gas separation system 1 of the present embodiment, the amount of purge gas and the time of one step are actually the same as those of the comparative example, so that the efficiency of carbon dioxide desorption by the purge gas can be improved as compared with the comparative example. I can say.

Further, according to the gas separation system 1 of the present embodiment, the outlet of the adsorber 10 which increases the energy for heating the adsorber 10 from the outside by connecting the two adsorbers 10 and reusing the purge gas is provided. Since the desorption efficiency of carbon dioxide can be improved without additionally inputting external energy such as by connecting to a vacuum pump, it is possible to suppress a decrease in energy efficiency.

According to the gas separation system 1 of the present embodiment, the desorption of carbon dioxide can be completed efficiently and in a short time by using a limited amount of purge gas, so that the size of the gas separation system 1 can be reduced. , Energy saving can be realized.

<Second Embodiment>
FIG. 11 is an explanatory diagram showing a schematic configuration of the gas separation system 1A of the second embodiment. The gas separation system 1A of the present embodiment further includes two adsorbers 14 and 15 and two connection flow paths 84 and 85 in addition to the configuration of the gas separation system 1 of the first embodiment. The adsorbers 14 and 15 have the same configuration as the adsorbers 11 to 13. The adsorber 13 is connected to the adsorber 14 via the connection flow path 83, the adsorber 14 is connected to the adsorber 15 via the connection flow path 84, and the adsorber 15 is connected to the adsorber 11 via the connection flow path 85. Is connected to. In the embodiments described below, the same configurations as those of the gas separation system 1 are designated by the same reference numerals, and the preceding description will be referred to.

FIG. 12 is an explanatory diagram of the switching timing of the adsorber 10 in the gas separation system 1A of the second embodiment. In the gas separation process of the present embodiment, as shown in the figure, step 1A, step 2A, step 3A, step 4A, and step 5A are set as one cycle, and this cycle is repeated a plurality of times. In each step, each of the adsorption step, the heating step, the first desorption step, the second desorption step, and the cooling step is performed in any of the five adsorbers 11, 12, 13, 14, and 15. .. Each of the steps 1A, 2A, 3A, 4A and 5A in the present embodiment is also referred to as a "suction / desorption step". Further, the adsorber 10 on which the first desorption step is performed is the "first adsorber", the adsorber 10 on which the second desorption step is performed is the "second adsorber", and the adsorber 10 on which the adsorption step is performed is "". Also called "third adsorber".

Specifically, in step 1A, the adsorption step is executed in the adsorber 11, the heating step is executed in the adsorber 12, the first desorption step is executed in the adsorber 13, and the second desorption step is executed in the adsorber 14. The process is executed and the cooling process is executed in the adsorber 15. In steps 2A, 3A, 4A and 5A, the adsorption / desorption step is performed by changing the adsorber 10 targeted for each of the adsorption step, the heating step, the first desorption step, the second desorption step, and the cooling step. Will be. In the gas separation system 1A of the present embodiment, carbon dioxide in the exhaust gas is adsorbed by any one adsorber 10, and at the same time, the other adsorber 10 is heated and adsorbed by the other two adsorbers 10. The carbon dioxide is desorbed and the other adsorber 10 is cooled.

Focusing on one adsorber 10, the adsorption step, the heating step, the first desorption step, the second desorption step, and the cooling step are repeated in this order. In the present embodiment, the heating step is provided independently of the desorption step, and heating is not performed in the second desorption step. Further, the cooling step is provided independently of the adsorption step.

FIG. 13 is an explanatory diagram of step 1A in the gas separation system 1A. In the gas separation system 1A, carbon dioxide is separated from the exhaust gas by sequentially supplying the exhaust gas (carbon dioxide-containing gas) to each of the five adsorbers 11, 12, 13, 14, and 15. In the gas separation system 1A as well, as in the first embodiment, the two adsorbers 10 are connected in series via the connection flow path 80, and the adsorber as the first adsorber in which the first desorption step is executed is executed. The purge gas flowing through the 10 is supplied to the adsorber 10 as the second adsorber on which the second desorption step is executed. In FIG. 13, the flow of the exhaust gas, the heat medium, and the purge gas (hydrogen) is shown by a thick solid line.

As shown in FIG. 13, in step 1A (FIG. 12), the adsorption step is performed by the adsorber 11, and the exhaust gas is supplied to the adsorber 11. Specifically, the exhaust gas inlet valve 21a is opened by the control unit 55, and the exhaust gas inlet valves 22a to 25a are closed, and the adsorber is opened via the carbon dioxide-containing gas supply flow path 20 and the exhaust gas branch flow path 21. Exhaust gas is supplied to 11. In the adsorber 11, carbon dioxide contained in the exhaust gas is trapped by the adsorbent 11a, and most of the gas such as nitrogen and water that is not trapped by the adsorbent 11a is treated as off gas outside the gas separation system 1, for example. Released into the atmosphere.

A heating step is performed on the adsorber 12, and a heat medium is supplied to the adsorber 12. Specifically, the heater 30a is controlled by the control unit 55 so that the heat medium reaches a predetermined temperature (heat input amount), the heat medium inlet valve 32a is opened, and the heat medium inlet valves 31a, 33a, 34a are opened. And 35a are closed and a heat medium is supplied. As a result, the heat medium flowing through the heat medium flow path 30 is supplied to the adsorber 12 via the heat medium distribution flow path 32. In the adsorber 12, when the heat medium is supplied, the temperature of the adsorbent 12a rises, and the carbon dioxide adsorbed on the adsorbent 12a is easily desorbed.

The first desorption step is performed on the adsorber 13, and the purge gas is supplied to the adsorber 13. Specifically, the purge gas inlet valve 73a is opened by the control unit 55, and the purge gas inlet valves 71a, 72a, 74a and 75a are closed and adsorbed via the purge gas supply flow path 70 and the purge gas branch flow path 73. Purge gas is supplied to the vessel 13. When the purge gas is supplied to the adsorber 13, the carbon dioxide adsorbed on the adsorbent 13a is desorbed from the adsorbent 13a. The carbon dioxide desorbed from the adsorbent 13a is mixed with the purge gas (hydrogen) inside the adsorber 13. In step 1A, since the mixed gas outlet valve 63a is closed and the connection flow path valve 83a is opened, the mixed gas discharged from the adsorber 13 is the mixed gas distribution flow path 63 and the connection flow path 83. , And flows into the adsorber 14 through the purge gas distribution channel 74.

The second desorption step is performed on the adsorber 14, and the above-mentioned mixed gas is supplied to the adsorber 14. When the mixed gas containing the purge gas is supplied to the adsorber 14, the carbon dioxide adsorbed on the adsorbent 14a is desorbed from the adsorbent 14a. The carbon dioxide desorbed from the adsorbent 14a is mixed with the mixed gas including the purge gas inside the adsorber 14. Since the mixed gas outlet valve 64a is opened in step 1A, the mixed gas discharged from the adsorber 14 is stored in the surge tank 40 through the mixed gas distribution flow path 64 and the mixed gas flow path 60.

A cooling step is performed on the adsorber 15, and a refrigerant is supplied to the adsorber 15 (not shown). When a heat medium having a relatively low temperature is supplied to the heat medium flow path of the adsorber 15, the adsorbent 15a is cooled and the temperature of the adsorbent 15a drops. As a result, the adsorbent 15a is in a state in which carbon dioxide is easily adsorbed. In step 1A of the present embodiment, the adsorber 11 is a "third adsorber", the adsorber 13 is a "first adsorber", and the adsorber 13 is a "second adsorber". Also in the gas separation system 1A of the present embodiment, the control unit 55 repeatedly executes the suction / desorption step by changing the first adsorber, the second adsorber, and the third adsorber.

As described above, also in the gas separation system 1A of the present embodiment, the purge gas that has passed through one adsorber 10 can be reused and flowed into another adsorber 10, so that carbon dioxide generated by the purge gas can be reused. Desorption efficiency can be improved.

<Third Embodiment>
The gas separation system of the third embodiment has the same configuration as the gas separation system 1A of the second embodiment, but the gas separation process by the control unit 55 is different from that of the second embodiment.

FIG. 14 is an explanatory diagram of the switching timing of the adsorber 10 in the gas separation system of the third embodiment. In the gas separation process of the present embodiment, as in the second embodiment, the process 1B, the process 2B, the process 3B, the process 4B, and the process 5B are set as one cycle, and this cycle is repeated a plurality of times. In each step, each of the adsorption step, the heating step, the first desorption step, the second desorption step, and the cooling step is performed in any of the five adsorbers 11, 12, 13, 14, and 15. .. Each of the steps 1B, 2B, 3B, 4B and 5B in the present embodiment is also referred to as a "suction / desorption step". Further, the adsorber 10 on which the first desorption step is performed is the "first adsorber", the adsorber 10 on which the second desorption step is performed is the "second adsorber", and the adsorber 10 on which the adsorption step is performed is "". Also called "third adsorber".

The difference between the gas separation treatment of the present embodiment and the gas separation treatment of the second embodiment is that the purge gas flowing through the first adsorber is passed through the connection flow path 80 during a part of the second desorption step. This is the point where the gas flows into the second adsorber. In the present embodiment, only in the latter half of the second desorption step, the purge gas flowing through the first adsorber is made to flow into the second adsorber via the connection flow path 80. In FIG. 14, “non-connected” is shown in the first half of the second desorption step, indicating that the first adsorber and the second adsorber are not connected and the purge gas is not supplied to the second adsorber. Shows. Further, "connection" is shown in the latter half of the second desorption step, indicating that the first adsorbent and the second adsorber are connected and the purge gas is supplied to the second adsorber.

FIG. 15 is an explanatory diagram of a second desorption step of step 1B of the third embodiment. FIG. 15 illustrates a part of the gas separation system of the third embodiment. FIG. 15A illustrates the first half (non-connecting step) of the second desorption step, and FIG. 15B illustrates the second half (connecting step) of the second decoupling step. In FIG. 15, the flow of purge gas (hydrogen) is shown by a thick solid line.

As shown in FIG. 14, in step 1B, the first desorption step is performed by the adsorbent 13, and the second desorption step is performed by the adsorber 14. Similar to the second embodiment, the purge gas is supplied to the adsorber 13 (FIG. 15). When the purge gas is supplied to the adsorber 13, the carbon dioxide adsorbed on the adsorbent 13a is desorbed from the adsorbent 13a, and the carbon dioxide desorbed from the adsorbent 13a is the purge gas (hydrogen) inside the adsorber 13. Is mixed with. As shown in FIG. 15A, in the first half of the second desorption step of step 1B, the mixed gas outlet valve 63a is opened and the connection flow path valve 83a is closed. That is, since the adsorber 13 as the first adsorber and the adsorber 14 as the second adsorber are not connected, the mixed gas discharged from the adsorber 13 is the mixed gas branch flow path 63 and the mixed gas flow. It passes through the road 60 and is stored in the surge tank 40.

In step 1B, when a predetermined time elapses, the process shifts to the connection step of the second desorption step. As shown in FIG. 15B, in the latter half of the second desorption step of step 1B, the mixed gas outlet valve 63a is closed and the connection flow path valve 83a is opened. That is, since the adsorber 13 as the first adsorber and the adsorber 14 as the second adsorber are connected, the mixed gas discharged from the adsorber 13 is the mixed gas branch flow path 63 and the connection flow path 83. , And flows into the adsorber 14 through the purge gas distribution channel 74. When the mixed gas containing the purge gas is supplied to the adsorber 14, the carbon dioxide adsorbed on the adsorbent 14a is desorbed from the adsorbent 14a and mixed with the mixed gas containing the purge gas inside the adsorber 14. Since the mixed gas outlet valve 64a is opened in the latter half of the step 1B, the mixed gas discharged from the adsorber 14 is stored in the surge tank 40 through the mixed gas distribution flow path 64 and the mixed gas flow path 60. To.

In the first half of the first desorption step, the carbon dioxide concentration of the mixed gas discharged from the first adsorber is high, so even if the mixed gas is passed through the second adsorber, the carbon dioxide desorption effect is small. Therefore, as in the gas separation process of the present embodiment, in the first half of the second desorption step, the first adsorber and the second adsorber are not connected, and the mixed gas having a high carbon dioxide concentration is stored in the surge tank 40. Then, in the latter half when the carbon dioxide concentration of the mixed gas discharged from the first adsorber decreases, the first adsorber and the second adsorber may be connected and the purge gas may be reused. Even in this way, the efficiency of carbon dioxide desorption by the purge gas can be improved.

<Fourth Embodiment>
FIG. 16 is an explanatory diagram showing a schematic configuration of the gas separation system 1C of the fourth embodiment. The gas separation system 1C of the present embodiment includes a vacuum pump 45 in addition to the configuration of the gas separation system 1A of the second embodiment. In the embodiments described below, the same configurations as those of the gas separation systems 1 and 1A are designated by the same reference numerals, and the preceding description will be referred to.

The vacuum pump 45 is provided in the decompression flow path 46 whose both ends are connected to the mixed gas flow path 60 between the adsorber 15 and the surge tank 40. The pressure reducing flow path 46 is provided with a switching valve 47 that controls the flow of the pressure reducing flow path 46 in response to a command from the control unit 55. Further, as shown in FIG. 16, a switching valve that controls the flow of the mixed gas flow path 60 in response to a command from the control unit 55 while both ends of the pressure reducing flow path 46 of the mixed gas flow path 60 are connected. 48 is provided. When the switching valve 48 is closed and the switching valve 47 is opened, the vacuum pump 45 is driven in response to a command from the control unit 55 to reduce the pressure inside the adsorber 10. In the gas separation system 1C of the present embodiment, the pressure in the adsorber 10 is reduced by the vacuum pump 45 during a part of the second desorption step.

In the fourth embodiment, as in the third embodiment, the purge gas flowing through the first adsorber flows into the second adsorber through the connection flow path 80 during a part of the second desorption step. Let me. In the present embodiment, unlike the third embodiment, only in the first half of the second desorption step, the purge gas flowing through the first adsorber is made to flow into the second adsorber through the connection flow path 80.

FIG. 17 is an explanatory diagram of the switching timing of the adsorber 10 in the gas separation system of the fourth embodiment. In the gas separation process of the present embodiment, as in the third embodiment, the process 1C, the process 2C, the process 3C, the process 4C, and the process 5C are set as one cycle, and this cycle is repeated a plurality of times. In each step, each of the adsorption step, the heating step, the first desorption step, the second desorption step, and the cooling step is performed in any of the five adsorbers 11, 12, 13, 14, and 15. .. Each of the steps 1C, 2C, 3C, 4C and 5C in the present embodiment is also referred to as a "suction / desorption step". Further, the adsorber 10 on which the first desorption step is performed is the "first adsorber", the adsorber 10 on which the second desorption step is performed is the "second adsorber", and the adsorber 10 on which the adsorption step is performed is "". Also called "third adsorber".

In FIG. 17, similarly to FIG. 14, the process in which the purge gas is supplied to the second adsorber is illustrated as “connected”, and the process in which the purge gas is not supplied to the second adsorber is illustrated as “non-connected”. In the present embodiment, as described above, the first adsorbent and the second adsorber are connected in the first half of the second desorption step, and the purge gas is supplied to the second adsorber. At this time, the vacuum pump 45 is not driven. In the latter half of the second desorption step, the first adsorber and the second adsorber are not connected, and the purge gas is not supplied to the second adsorber. At this time, the vacuum pump 45 is driven. As described above, in the present embodiment, the vacuum pump 45 is not driven in the first half of the second desorption step, and the vacuum pump 45 is driven in the second half of the second desorption step.

FIG. 18 is an explanatory diagram of a second desorption step of step 1C of the fourth embodiment. FIG. 18 illustrates a part of the gas separation system 1C. FIG. 18A illustrates the first half (connecting step) of the second desorption step, and FIG. 18B illustrates the second half (non-connecting step) of the second decoupling step. As shown in the figure, the vacuum pump 45 is not driven in the first half of the second desorption step, and the vacuum pump 45 is driven in the second half of the second desorption step. In FIG. 18, the flow of purge gas (hydrogen) is shown by a thick solid line.

As shown in FIG. 17, in step 1C, the first desorption step is performed by the adsorbent 13, and the second desorption step is performed by the adsorber 14. Similar to the second embodiment, the purge gas is supplied to the adsorber 13 (FIG. 18). When the purge gas is supplied to the adsorber 13, the carbon dioxide adsorbed on the adsorbent 13a is desorbed from the adsorbent 13a, and the carbon dioxide desorbed from the adsorbent 13a is the purge gas (hydrogen) inside the adsorber 13. Is mixed with. As shown in FIG. 18A, in the first half of the second desorption step of step 1C, the mixed gas outlet valve 63a is closed and the connection flow path valve 83a is opened. Further, the switching valve 47 is closed, the vacuum pump 45 is stopped, and the switching valve 48 is opened. That is, since the adsorber 13 as the first adsorber and the adsorber 14 as the second adsorber are connected, the mixed gas discharged from the adsorber 13 is the mixed gas branch flow path 63 and the connection flow path 83. , And flows into the adsorber 14 through the purge gas distribution channel 74. When the mixed gas containing the purge gas is supplied to the adsorber 14, the carbon dioxide adsorbed on the adsorbent 14a is desorbed from the adsorbent 14a and mixed with the mixed gas containing the purge gas inside the adsorber 14. Since the mixed gas outlet valve 64a is opened in the first half of step 1C, the mixed gas discharged from the adsorber 14 is stored in the surge tank 40 through the mixed gas distribution channel 64 and the mixed gas flow path 60. To.

In step 1C, when a predetermined time elapses, the process shifts to the connection step of the second desorption step. As shown in FIG. 18B, in the latter half of the second desorption step of step 1C, the mixed gas outlet valve 63a is opened and the connection flow path valve 83a is closed. Further, the switching valve 47 is opened, the vacuum pump 45 is driven, and the switching valve 48 is closed. That is, since the adsorber 13 as the first adsorber and the adsorber 14 as the second adsorber are not connected, the mixed gas discharged from the adsorber 13 is the mixed gas branch flow path 63 and the mixed gas flow path. 60, it is stored in the surge tank 40 through the decompression flow path 46.

In the present embodiment, in the latter half of the second desorption step, the vacuum pump 45 is used to assist the desorption of carbon dioxide. In this case, if the adsorber 13 and the adsorber 14 are connected, the desorption of carbon dioxide in the adsorber 14 as the second adsorber will be assisted, and the carbon dioxide in the adsorber 13 as the first adsorber will be assisted. Cannot be efficiently desorbed. In the present embodiment, in the first half of the second desorption step, the first adsorber and the second adsorber are connected to reuse the purge gas to improve the desorption efficiency of carbon dioxide by the purge gas, and the second desorption is performed. In the latter half of the desorption step, the first adsorber and the second adsorber are not connected, and the vacuum pump 45 is used to improve the carbon dioxide desorption rate of the first adsorber. Even in this way, the efficiency of carbon dioxide desorption by the purge gas can be improved.

<Fifth Embodiment>
FIG. 19 is an explanatory diagram showing a schematic configuration of the hydrocarbon production system 5 of the fifth embodiment. The hydrocarbon production system 5 of the present embodiment is an apparatus for producing methane (CH ₄ ) using a mixed gas of carbon dioxide (CO ₂ ) and hydrogen (H ₂ ), and is a gas separation system 1 and a hydrocarbon. A generation unit 8 is provided. In addition, this embodiment can be applied to a hydrocarbon production apparatus for producing a hydrocarbon compound other than methane, for example, a compound composed of carbon and hydrogen such as ethane and propane, and mainly carbon such as methanol. It can also be applied to a "hydrocarbon production apparatus" that produces a compound composed of hydrogen and hydrogen as a "hydrocarbon compound".

In the present embodiment, the surge tank 40 temporarily stores the mixed gas flowing through the mixed gas flow path 60. The mixed gas stored in the surge tank 40 is sent to the hydrocarbon generation unit 8. The hydrocarbon generation unit 8 produces methane using a mixed gas of carbon dioxide and hydrogen supplied by the surge tank 40. The produced methane is supplied to an external device of the hydrocarbon production system 5.

As described above, the hydrocarbon production system 5 of the present embodiment includes the gas separation system 1 and uses carbon dioxide separated from the exhaust gas by the gas separation system 1 and hydrogen as a purge gas as a hydrocarbon. Produces methane. Therefore, a hydrocarbon compound having high purity can be produced. Further, as described above, since the gas separation system 1 has improved the carbon dioxide desorption efficiency by the purge gas by reusing the purge gas, the hydrocarbon generation efficiency in the hydrocarbon generation unit 8 can be improved. .. In addition, the amount of surplus hydrogen in the production of methane in the hydrocarbon generation unit 8 can be reduced.

<Modified example of this embodiment>
The present invention is not limited to the above embodiment, and can be carried out in various embodiments without departing from the gist thereof, and for example, the following modifications are also possible.

-In the above embodiment, a gas other than hydrogen may be used as the purge gas. For example, a rare gas such as helium or neon, water vapor, methane, or a mixed gas containing at least one of them can be used. When a gas other than hydrogen is used as the purge gas in the hydrocarbon production system 5 of the fifth embodiment, a hydrogen supply unit that supplies hydrogen to the hydrocarbon generation unit 8 may be provided. However, it is preferable to use hydrogen as the purge gas because high-purity hydrocarbons can be generated in the hydrocarbon generation unit 8.

-The number of the adsorbers 10 is not limited to the above embodiment, and may be 4 or less, or 6 or more.

-In the above embodiment, the purge gas is supplied to the first adsorber, the mixed gas containing the purge gas and carbon dioxide discharged from the first adsorber is supplied to the second adsorber, and the mixture is discharged from the second adsorber. Although the example in which the gas is stored in the surge tank 40 is shown, a plurality of adsorbers may be connected in series to the second adsorber. For example, when the 4th adsorber, the 5th adsorber, and the 6th adsorber are connected in series after the 2nd adsorber, the mixed gas discharged from the 2nd adsorber is supplied to the 4th adsorber. , The mixed gas containing the desorbed carbon dioxide in the 4th adsorber and discharged from the 4th adsorber is supplied to the 5th adsorber, and the 5th adsorber containing the desorbed carbon dioxide in the 5th adsorber. The mixed gas discharged from the sixth adsorber is supplied to the sixth adsorber, and the mixed gas containing the carbon dioxide desorbed in the sixth adsorber and discharged from the sixth adsorber is stored in the surge tank 40. By doing so, although the amount of carbon dioxide desorbed in one step becomes smaller in the later stage, the carbon dioxide in the adsorber 10 can be desorbed by reusing the purge gas, so that the carbon dioxide is desorbed by the purge gas. The release efficiency can be improved. However, when the mixed gas discharged from the upper adsorber 10 is saturated with carbon dioxide, carbon dioxide cannot be desorbed by the latter adsorber 10, so that the adsorbers are connected in series in the desorption step. It is preferable that the number of the vessels 10 is appropriately set so that carbon dioxide can be desorbed even in the adsorbent 10 in the subsequent stage according to the supply amount of the purge gas and the time of one step.

-In the above embodiment, an example is shown in which carbon dioxide is desorbed by performing a so-called temperature swing that raises the temperature of the adsorbent in addition to flowing the purge gas, but the purge gas is flowed without performing the temperature swing. Carbon dioxide may be desorbed only by this. Further, in addition to the supply of the purge gas, the pressure may be reduced by using a vacuum pump, or a temperature swing may be performed.

-In the third embodiment, in the latter half of the second desorption step, an example in which the purge gas flowing through the first adsorber is made to flow into the second adsorber through the connection flow path is shown, and the fourth embodiment is described. In the first half of the second desorption step, an example in which the purge gas flowing through the first adsorber flows into the second adsorber through the connection flow path is shown, but the first adsorber and the second adsorber are shown. The period for reusing the purge gas by connecting to the above embodiment is not limited to the above embodiment. For example, the second desorption step is divided into three periods, the first half, the middle half, and the second half. In the first half, the first adsorber and the second adsorber are not connected, and only the first adsorber desorbs carbon dioxide. In the middle period, the first adsorber and the second adsorber are connected (multi-staged), carbon dioxide is desorbed by the first adsorber and the second adsorber, and the first adsorber is used again in the latter period. The connection with the second adsorber may be disconnected and carbon dioxide may be desorbed only by the first adsorber.

-In the third and fourth embodiments, the presence or absence of the connection of the adsorber in the second desorption step is switched according to the passage of time, but the present invention is not limited to this. For example, the connection is switched according to the carbon dioxide concentration of the mixed gas discharged from the first adsorber, such as connecting (multi-stage) when the carbon dioxide concentration of the mixed gas discharged from the first adsorber is low. You may. Further, the presence or absence of connection may be switched according to the carbon dioxide desorption rate, such as disconnecting the connection when the carbon dioxide desorption rate from the adsorber is high (single adsorber).

In the above embodiment, an example is shown in which the mixed gas branch flow path and the purge gas branch flow path are connected by a connection flow path 80 as a bypass flow path, but the connection flow path is not limited to the above embodiment. For example, the connection flow path 80 may be provided separately from the mixed gas branch flow path and the purge gas branch flow path. When the connection flow path 80 is provided separately from the mixed gas branch flow path and the purge gas branch flow path, the flow direction of the purge gas in the first adsorber and the flow direction of the purge gas in the second adsorber are the same as in the above embodiment. They may be connected so as to be the same (for example, the lower side of the drawing of the first adsorber and the second adsorber are connected by the connection flow path 80), or the flow direction of the purge gas in the first adsorber and the second. The flow direction of the purge gas in the adsorber may be different from that of the flow direction, and the gas may be connected so as to turn (for example, the lower side of the drawing of the first adsorber and the lower side of the drawing of the second adsorber are connected by the connection flow path 80. ).

-It is not necessary to provide the surge tank in the above embodiment. If there is a surge tank, the ratio of hydrogen and carbon dioxide in the mixed gas can be stabilized, and the ratio of hydrogen and carbon dioxide can be kept within the target range without adjusting the flow rate of hydrogen sequentially. ,preferable.

-As another embodiment, a carbon dioxide cycle system or a hydrocarbon-fueled fuel production system may be configured. For example, the carbon dioxide circulation system is supplied from the hydrocarbon production system 5 of the fifth embodiment, methane supplied from the hydrocarbon generation unit 8 of the hydrocarbon production system 5, and the surge tank 40 of the hydrocarbon production system 5. A combustor using the carbon dioxide produced and the air in the atmosphere is provided, and the carbon dioxide is circulated by supplying the exhaust gas discharged from the combustor to the hydrocarbon production system 5. Further, the fuel production system includes the hydrocarbon production system 5 of the fifth embodiment and the fuel production unit, and produces fuel by using the hydrocarbon produced by the hydrocarbon production system 5.

Although the present invention has been described above based on the embodiments and modifications, the embodiments of the above-described embodiments are for facilitating the understanding of the present invention and do not limit the present invention. The present invention may be modified or improved without departing from the spirit and claims, and the present invention includes an equivalent thereof. Further, if the technical feature is not described as essential in the present specification, it may be deleted as appropriate.

1, 1A, 1C, 1P ... Gas separation system 5 ... Hydrocarbon production system 8 ... Hydrocarbon generator 10, 11, 12, 13, 14, 15 ... Adsorber 11a, 12, 13a, 14a, 15a ... Adsorbent 20 ... Carbon dioxide-containing gas supply flow path 21, 22, 23 ... Exhaust gas distribution channel 21a, 22a, 23a ... Exhaust gas inlet valve 30 ... Heat medium flow path 30a ... Heater 31, 32 ... Heat medium distribution flow path 31a, 32a ... Heat medium inlet Valve 40 ... Surge tank 45 ... Vacuum pump 46 ... Decompression flow path 47, 48 ... Switching valve 55 ... Control unit 60 ... Mixed gas flow path 61, 62, 63, 64 ... Mixed gas branch flow path 61a, 62a, 63a, 64a ... Mixing gas outlet valve 70 ... Purge gas supply flow path 70a ... Flow controller 71, 72, 73, 74 ... Purge gas distribution flow path 71a, 72a, 73a ... Purge gas inlet valve 80, 81, 82, 83, 84, 85 ... Connection flow path 81a, 82a, 83a, 84a, 85a ... Connection flow path valve

Claims (5)

It is a gas separation system equipped with a plurality of adsorbers that house an adsorbent capable of adsorbing carbon dioxide inside.
Of the plurality of adsorbers, a connection flow path capable of connecting the first adsorber and the second adsorber in series, and
A purge gas supply flow path capable of supplying the purge gas to the first adsorbent,
With carbon dioxide adsorbed on the first adsorber and the second adsorber, the purge gas is supplied to the first adsorber via the purge gas supply flow path, and carbon dioxide is supplied from the first adsorber. The second adsorber is connected to the first adsorber via the first desorption step and the connection flow path, and the purge gas flowing through the first adsorber is passed through the connection flow path. A control unit that can simultaneously execute the second desorption step of flowing into the second adsorber and desorbing carbon dioxide from the second adsorber.
To prepare
Gas separation system. The gas separation system according to claim 1.
Further provided with a carbon dioxide-containing gas supply channel capable of supplying the carbon dioxide-containing gas containing carbon dioxide to the first adsorbent and the third adsorber different from the second adsorber.
The control unit
The adsorption step of supplying the carbon dioxide-containing gas to the third adsorber and adsorbing the carbon dioxide through the carbon dioxide-containing gas supply flow path can be executed at the same time as the first desorption step.
The first desorption step, the second desorption step, and the adsorption / desorption step including the adsorption step, which are simultaneously executed, are carried out by each of the first desorption step, the second desorption step, and the adsorption step. The first adsorber, the second adsorber, and the third adsorber to be executed can be changed and repeatedly executed.
Gas separation system. The gas separation system according to claim 1 or 2.
The control unit
During a part of the period of the second desorption step, the purge gas flowing through the first adsorber is made to flow into the second adsorber through the connection flow path.
Gas separation system. The gas separation system according to any one of claims 1 to 3.
The purge gas is hydrogen.
Gas separation system. It ’s a hydrocarbon production system.
The gas separation system according to claim 4 and
It comprises a hydrocarbon generator that is connected to the gas separation system and uses a mixed gas of carbon dioxide separated by the gas separation system and hydrogen used as the purge gas to generate a hydrocarbon compound.
Hydrocarbon production system.

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