JP6662658B2 - Carbon dioxide recovery method and gas separation membrane module - Google Patents

Description

  The present invention relates to a method for recovering carbon dioxide and a gas separation membrane module.

At present, in order to prevent global warming, which is a global problem, it is required to reduce the amount of greenhouse gas, mainly carbon dioxide gas generated from human activities, to the outside air. However, in terms of energy security, it is not realistic to rapidly change the direction of conventional energy production methods centered on fossil fuels. Therefore, technology development with high energy efficiency and low generation of carbon dioxide gas and its application are being sought.
As one of them, a method is proposed in which an integrated coal gasification combined cycle (IGCC) technology is combined with an efficient carbon dioxide separation and capture technology.

Among the carbon dioxide separation and capture technologies, as a promising technology, the technical development of an accelerated transport membrane, which is one of the gas separation membranes, is being performed. Efficient and selective separation of carbon dioxide from the mixed gas of hydrogen and carbon dioxide obtained mainly by gasification of coal by IGCC using the above-mentioned gas separation membrane, and the high-purity carbon dioxide is used as an industrial raw material, etc. In addition to utilization, use for EOR and carbon dioxide storage is being studied. The term “EOR” as used herein means an enhanced recovery technique represented by a CO ₂ injection method.
Also, it has been studied to efficiently perform hydrogen combustion power generation and power generation for a fuel cell using high-purity hydrogen gas, a non-permeate gas obtained by separating carbon dioxide gas. To this end, it is necessary to increase the selectivity (carbon dioxide selectivity) and the carbon dioxide permeability of the separation of carbon dioxide by the separation membrane, and to recover carbon dioxide at a high concentration and a high recovery rate.

Among the technologies for separating and recovering carbon dioxide, a gas separation membrane that is a facilitated transport membrane described in Patent Literature 1 is known as an expected technology. A gas separation membrane module is configured using the gas separation membrane, and a mixed gas containing water (steam) and carbon dioxide is supplied to one surface of the gas separation membrane. When the carbon dioxide is ionized by the gas separation membrane, the carbon dioxide selectively passes through the gas separation membrane.
The most important thing for this is to establish a technique for supplying an appropriate amount of water vapor to the facilitated transport membrane. There is a need to construct an optimal membrane element and membrane module structure, secure required gas properties, and provide a membrane system at an acceptable cost.

JP 2012-192316 A

The accelerated transport system that has been announced to date complies with its gas permeation performance and separation performance, and because of the necessity of supplying steam, the system uses a booster such as a compressor to compensate for the pressure drop of the permeate gas. This is a multi-stage membrane module system. Furthermore, a method of supplying steam by a sweep gas method to the permeation side for supplying steam has been adopted, and an operation at a high temperature of 100 ° C. or higher where the partial pressure of steam is high has been proposed.
However, in the current technology, the multi-stage membrane module requires input of external energy such as electric power by operating the compressor for the mixed gas as described above, so that the original purpose is to prevent global warming and reduce carbon dioxide. Would go backwards. Then, a large amount of power cost is generated, and the cost is not practical. A single-stage / all-parallel system may be considered in order to avoid the pressure increase of the separation gas in the middle, but it is out of the question because it is known that this system cannot achieve the target separation gas performance such as gas purity and gas recovery rate. Further, a technique for supplying an appropriate amount of water vapor to the facilitated transport membrane has not been established. For example, a method of simply introducing steam together with the mixed gas can be considered, but even if such a method is used, the supply amount of steam is not sufficient, and it is difficult to efficiently separate carbon dioxide.

Here, if the pressure of the steam is increased by supplying the steam to be supplied at a temperature higher than 100 ° C., the partial pressure of the steam is increased. For this reason, it becomes possible to sufficiently supply steam to the facilitated transport membrane, and it is possible to improve the separation efficiency of carbon dioxide.
However, in order to supply high-temperature steam, it is necessary to use a polymer material having a heat resistance of 100 ° C. or higher as a component for protecting the facilitated transport membrane or a material for forming the gas separation membrane. In this case, an expensive material must be used. Further, a larger energy for heating the steam is required. In the sweep method in which the swirling of the piping becomes complicated on the system, the operation becomes complicated, and the membrane performance tends to be reduced and the membrane area increases due to an increase in pressure loss in the permeate-side flow path. As a result, the system becomes unstable, leading to a problem that the device becomes complicated and the cost increases. For this reason, it has not been put to practical use until now, except for some special cases where the gas separation performance and cost need not be considered.

  The non-permeated gas of the mixed gas that has not been permeated through the gas separation membrane is exhausted after being appropriately processed. However, there is a demand for a method of recovering carbon dioxide that reduces the carbon dioxide gas in the non-permeated gas to be exhausted and improves the recovery rate of the carbon dioxide gas.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide a carbon dioxide recovery method and a gas separation membrane module capable of efficiently recovering carbon dioxide gas from a mixed gas. .

In order to solve the above problems, the present invention proposes the following means.
The carbon dioxide recovery method of the present invention is a carbon dioxide recovery method for recovering carbon dioxide gas from a mixed gas containing carbon dioxide gas, wherein a suction hole is formed on an outer peripheral surface while extending in a direction along an axis. the collection tube were, first gas separation membrane and the second gas separation membrane is the gas separation membrane of carbon dioxide gas is selectively permeable to ions of the mixed gas by the supply of water, the said axis Supplying the mixed gas to one surface of the first gas separation membrane in a state where the mixed gas is provided so as to be wound around the outer peripheral surface of the collection pipe at intervals in a direction along the mixture; While collecting the carbon dioxide gas permeated by the first gas separation membrane out of the gas from the suction hole into the collection pipe, the non-gas of the mixed gas not permeated by the first gas separation membrane is removed. Transparent gas The supplying steam of a wet non-permeate gas, the second supplying the humidified non-permeate gas on one side of the gas separation membrane, wherein said carbon dioxide gas which is transmitted by the second gas separation membrane It is characterized in that it is collected from the suction hole into the collection pipe .
The collection pipe, the first gas separation membrane and the second gas separation membrane are arranged in a container body, and when supplying the mixed gas to the first gas separation membrane, the second gas separation membrane in the container body Conveying the mixed gas through a portion upstream of one gas separation membrane, and supplying the humidified non-permeate gas to the second gas separation membrane, the first gas separation membrane in the container body and the The humidified non-permeable gas may be transported through a portion between the second gas separation membrane and the second gas separation membrane.

Further, the gas separation membrane module of the present invention is a gas separation membrane module for recovering carbon dioxide gas from a mixed gas containing carbon dioxide gas, wherein the gas separation membrane module extends in the direction along the axis and has a suction hole formed on the outer peripheral surface. a collection tube was, in the collection tube, at intervals in a direction along said axis and provided so as to be wound around the outer peripheral surface of the collection tube, the carbon dioxide in the mixed gas by the supply of water A first gas separation membrane and a second gas separation membrane, which are gas separation membranes for ionizing and selectively transmitting a gas and collecting the carbon dioxide gas from the suction hole into the collection pipe; The mixed gas is supplied to one surface of the gas separation membrane, and the non-permeated gas that is not permeated by the first gas separation membrane in the mixed gas is transported, and one of the second gas separation membranes is transported. Front to face A transport unit that supplies a non-permeate gas, and a humidifier that supplies water vapor to the non-permeate gas before being supplied to the second gas separation membrane to make it a humidified non-permeate gas. And
The collecting pipe, the first gas separation membrane and the second gas separation membrane comprising a container body disposed therein, the transport unit, the container body upstream of the first gas separation membrane in the And a portion of the container body between the first gas separation membrane and the second gas separation membrane.

  According to these inventions, when the mixed gas is supplied to the first gas separation membrane, since the water vapor in the mixed gas permeates the first gas separation membrane, the relative humidity of the non-permeated gas becomes equal to the relative humidity of the mixed gas. It is lower than that. The selectivity (membrane performance) of carbon dioxide gas to hydrogen gas permeating the gas separation membrane is improved when the relative humidity of the supplied gas is relatively high. By supplying water vapor to the non-permeating gas to make it a humidified non-permeating gas, the relative humidity of the humidified non-permeating gas becomes higher than the relative humidity of the non-permeating gas.

Further, in the above-described method for recovering carbon dioxide, the amount of the water vapor supplied to the non-permeate gas may be adjusted so that the relative humidity of the humidified non-permeate gas becomes 50% or more and 80% or less.
Further, in the above gas separation membrane module, further comprising a humidity sensor for detecting the relative humidity of the humidified non-permeating gas, and a control unit for adjusting the flow rate of the water vapor supplied by the humidification unit, the control unit, The relative humidity of the non-humidified gas may be adjusted by the humidifying unit based on the detection result of the humidity sensor to be 50% or more and 80% or less.
According to these inventions, when the relative humidity of the gas to be passed through the gas separation membrane is 50% or more and 80% or less, the selectivity of the gas separation membrane is maximized.

Further, in the above method for recovering carbon dioxide, the temperature of the mixed gas supplied to the first gas separation membrane may be set to 100 ° C. or lower.
Further, in the gas separation membrane module described above, a temperature adjustment unit that adjusts the temperature of the mixed gas that the conveyance unit supplies to the first gas separation membrane, and the conveyance unit includes the first gas separation membrane. A temperature sensor for detecting the temperature of the mixed gas being supplied to the control unit, and a control unit for adjusting the temperature of the mixed gas, wherein the control unit adjusts the temperature based on a detection result of the temperature sensor. The temperature of the mixed gas may be adjusted so as to be 100 ° C. or less by a unit.
According to these inventions, since the gas separation membrane has the polymer membrane, when the temperature of the mixed gas exceeds 100 ° C., the decomposition of the molecular structure proceeds.

  Further, in the above-mentioned method for recovering carbon dioxide, water vapor is supplied to the mixed gas to adjust the relative humidity of the mixed gas to 50% or more and 80% or less, and then the mixed gas is supplied to the first gas separation membrane. May be supplied.

In the present invention, according to the method for recovering carbon dioxide according to claim 1 and the gas separation membrane module according to claim 6 , the relative humidity of the humidified non-permeated gas is higher than the relative humidity of the non-permeated gas. Thus, the carbon dioxide gas can be efficiently recovered from the mixed gas.
According to the method for recovering carbon dioxide according to the second aspect and the gas separation membrane module according to the seventh aspect , the selectivity of the gas separation membrane is increased, so that the carbon dioxide gas can be more efficiently removed from the mixed gas. Can be recovered.

According to the gas separation membrane module according to the recovery method and claim 8 of carbon dioxide according to claim 3, may be the molecular structure of the first gas separation membrane suppressed to decompose.
According to the method for recovering carbon dioxide according to claim 4 , the selectivity of the gas separation membrane in the first gas separation membrane is increased, so that the carbon dioxide gas can be more efficiently recovered from the mixed gas. it can.

It is a figure showing typically the gas separation membrane device using the gas separation membrane module of one embodiment of the present invention. It is the perspective view which made a part of the gas separation membrane module permeate. It is a perspective view which shows and fractures | ruptures some gas separation membrane elements. It is a flow chart which shows a carbon dioxide recovery method in one embodiment of the present invention.

  Hereinafter, an embodiment of a gas separation membrane module according to the present invention will be described with reference to FIGS. As shown in FIG. 1, a gas separation membrane device 1 using the present gas separation membrane module 10 is for recovering a carbon dioxide gas G1 from a mixed gas G0 containing a carbon dioxide gas.

As shown in FIG. 1, the gas separation membrane device 1 of the present embodiment is configured by connecting, for example, a gas separation membrane module 10 in which a plurality of gas separation membrane elements 11 are connected in series. The number of gas separation membrane elements 11 constituting one gas separation membrane module 10 is not particularly limited as long as it is plural. The number of the gas separation membrane modules 10 constituting the gas separation membrane device 1 may be one or two or more.
The number of the gas separation membrane elements 11 constituting the gas separation membrane module 10 and the number of the gas separation membrane modules 10 constituting the gas separation membrane device 1 depend on the amount of the mixed gas G0 processed by the gas separation membrane device 1 and the like. It is set according to.
Hereinafter, one gas separation membrane module 10 will be described with an example in which the gas separation membrane element 11 is a spiral membrane type.

The gas separation membrane module 10 shown in FIG. 2 is a module in which, for example, three gas separation membrane elements 11 are connected in series without increasing the pressure of the mixed gas G0 on the way by a booster such as a compressor as described later. is there. Such a configuration of the gas separation membrane module 10 is called a series division system. In FIG. 2, a container main body 35 described later is shown transparently.
For convenience of description, when the three gas separation membrane elements 11 are separately referred to, the gas separation membrane element 11A, the gas separation membrane element 11B, and the gas separation membrane element 11C are sequentially arranged from the upstream side D1 through which the mixed gas G0 flows to the downstream side D2. Called. The three gas separation membrane elements 11 are arranged at intervals in the longitudinal direction of the gas separation membrane module 10.

  The gas separation membrane module 10 includes a vessel 13, a collection pipe 14 and three gas separation membrane elements 11 arranged in the vessel 13, a first humidifier 16 provided in the vessel 13, and a second humidifier ( Humidifier 17), third humidifier 18, temperature controller 20, temperature sensor 22, first humidity sensor 24, second humidity sensor (humidity sensor) 25, third humidity sensor 26, fourth humidity It has a sensor 27 and a control unit 29 for controlling the humidifying units 16, 17, 18 and the temperature adjusting unit 20.

The vessel 13 includes a container body 35 formed in a cylindrical shape around the axis C, a first lid 36 that closes a first opening that is an opening on the upstream side D1 of the container body 35, and a container body 35. And a second lid portion 37 that closes a second opening that is an opening on the downstream side D2. The container body 35 can be formed of a steel pipe or the like, and the lids 36 and 37 can be formed of cast iron, cast steel, a steel plate, or the like.
The number of the gas separation membrane elements 11 arranged in the container body 35 is not limited to three, but may be one, two, or four or more.

Here, the configuration of the collection pipe 14 and the gas separation membrane element 11 will be described.
As shown in FIG. 3, the collection tube 14 is a tubular member extending in a direction along the axis C. A plurality of suction holes 14 a are formed on the outer peripheral surface of the collection pipe 14. The plurality of suction holes 14a are arranged separately from each other in a direction along the axis C, and communicate the inside and outside of the collection tube 14. The collection tube 14 is arranged in the container body 35 as shown in FIG.
The end of the collection tube 14 on the side of the second lid 37 is disposed inside the container body 35. On the other hand, the end of the collection tube 14 on the first lid 36 side penetrates the first lid 36.
In this example, the case where the carbon dioxide gas G1 which is the permeate gas is countercurrent to the mixed gas G0 which is the supply gas has been described. The end on the side of the lid 36 is disposed inside the container body 35. On the other hand, the end of the collection tube 14 on the second lid 37 side penetrates the second lid 37.

As shown in FIG. 3, the gas separation membrane element 11A is formed by stacking a first gas separation membrane 45A, which is a gas separation membrane, and a supply spacer 46A.
The gas separation membrane, which is a facilitated transport membrane, is a membrane that ionizes and selectively transmits carbon dioxide gas G1 in the mixed gas G0 or the like by supplying water. This gas separation membrane has a polymer membrane. Specifically, for example, it is a film formed from a polymer having a primary amino group and a vinyl alcohol-based polymer having a carboxyl group.
The gas separation membrane is not limited to this, and may be any membrane that requires water containing an amine compound and a polyvinyl alcohol-based polymer or a polyethylene glycol-based polymer. Further, the gas separation membrane may be a membrane containing an inorganic compound.

In this gas separation membrane, when the relative humidity of the supplied gas such as the mixed gas G0 is relatively high, the selectivity of carbon dioxide gas to hydrogen gas permeating the gas separation membrane is improved.
When the relative humidity of the gas is 50% or more and 80% or less, the gas separation membrane, which is the facilitated transport membrane of the present embodiment, has the highest selectivity of the gas separation membrane. The amount of water vapor supplied by the humidifying unit 16 or the like is set so that the relative humidity of the gas contacting the gas separation membrane is 50% or more and 80% or less in any part of the gas separation membrane of the gas separation membrane element 11A. It is preferable to decide.

The first gas separation membrane 45A and the supply spacer 46A are stacked in the radial direction of the collection pipe 14 to form a stacked member. That is, the first gas separation membrane 45A, the permeable spacer 49A, the first gas separation membrane 45A, and the supply spacer 46A are provided in this order so as to be wound around the outer peripheral surface of the collection tube 14 in a multiplex cylindrical shape. The gas separation membrane element 11A which is a laminated member is formed. When the mixed gas is supplied to the supply spacer 46A, the mixed gas G0 is supplied to one surface 45A1 of the first gas separation film 45A sandwiching both sides thereof. Further, the permeated gas that has passed through the first gas separation membrane 45A passes through the space of the permeation spacer 49A provided between the first gas separation membrane 45A and the first gas separation membrane 45A to the collection pipe 14. Conveyed.
The gas separation membrane element 11A, which is a cylindrical laminated member, is disposed in the container body 35, and the collection pipe 14 is inserted into the cylinder hole of the gas separation membrane element 11A. The mixed gas G0 is supplied to one surface 45A1, etc. of the first gas separation membrane 45A.

The gas separation membrane elements 11B and 11C have the same configuration as the gas separation membrane element 11A.
For example, the gas separation membrane element 11B shown in FIG. 3 uses a second gas separation membrane 45B, which is a gas separation membrane, instead of the first gas separation membrane 45A of the gas separation membrane element 11A. However, the second gas separation membrane 45B has the same configuration as the first gas separation membrane 45A.
A first humidified non-permeate gas G5 described later is supplied to one surface 45B1 and the like of the second gas separation membrane 45B.

The container body 35 will be described again.
As shown in FIG. 2, a gas supply pipe 39 and a steam supply pipe of the first humidifying unit 16 are provided in a first transport pipe 35 a, which is a part of the container main body 35 on the upstream side D1 from the gas separation membrane element 11 </ b> A. 16a is attached.
In addition, the part between the gas separation membrane element 11A and the gas separation membrane element 11B in the container main body 35 becomes the second transport pipe 35b. Similarly, a portion between the gas separation membrane element 11B and the gas separation membrane element 11C in the container body 35 becomes a third transfer pipe 35c, and a portion on the downstream side D2 of the gas separation membrane element 11C in the container body 35 is the third transport pipe 35c. This is the fourth transfer pipe 35d. The first transport pipe 35a and the second transport pipe 35b constitute a transport section 35e.

The gas supply pipe 39 is provided with the above-mentioned temperature controller 20. In general, the mixed gas G0 is supplied to the gas separation membrane device 1 at a temperature higher than 100 ° C. from a power generation facility or the like, and thus the temperature control unit 20 mainly uses a cooler. As the temperature control unit 20, for example, a known cooling circuit having a heat exchange medium can be used. The temperature control unit 20 controls the temperature of the mixed gas G0 supplied to the gas separation membrane element 11A (the first gas separation membrane 45A) by the first transfer pipe 35a.
The steam supply pipe 16a is provided with a first flow control valve 16b. Although not shown, a steam generating means such as a boiler or a heat exchanger is provided on the side of the steam supply pipe 16a opposite to the container body 35. The temperature controller 20 for cooling the mixed gas G0 may be used as steam generating means, and steam W may be generated by exchanging heat between the mixed gas G0 and water in the temperature controller 20. Alternatively, the mixed gas G0 and steam produced by another method may be mixed outside the container body 35.
The steam supply pipe 16a, the first flow rate control valve 16b, and the steam generation means constitute a first humidifier 16 for supplying steam W to the mixed gas G0 flowing in the first transport pipe 35a.

The first flow control valve 16b controls the steam W in the steam supply pipe 16a from a fully closed state in which the steam W does not flow in the steam supply pipe 16a to a fully opened state in which the maximum flow rate of the steam W flows in the steam supply pipe 16a. Can be continuously adjusted. The first flow control valve 16b is connected to the control unit 29 and is controlled by the control unit 29.
The temperature sensor 22 and the first humidity sensor 24 are attached to a portion on the downstream side D2 of the portion where the gas supply pipe 39 and the first humidifying section 16 are attached to the first transport pipe 35a. The temperature sensor 22 detects the temperature of the mixed gas G0 supplied to the gas separation membrane element 11A by the first transfer pipe 35a. The first humidity sensor 24 detects the relative humidity of the mixed gas G0 supplied to the gas separation membrane element 11A.
The temperature sensor 22 and the first humidity sensor 24 are connected to the control unit 29 and transmit detection results to the control unit 29.

The second humidifier 17 and the third humidifier 18 are configured similarly to the first humidifier 16. That is, the second humidifying unit 17 includes a steam supply pipe 17a attached to the second transport pipe 35b, a second flow rate control valve 17b provided in the steam supply pipe 17a, and the above-described steam generation means. Have. The second humidifying unit 17 supplies water vapor W to a later-described first non-permeable gas G2 flowing in the second transport pipe 35b to be a later-described first humidified non-permeable gas G5.
The third humidifying section 18 has a steam supply pipe 18a attached to the third transport pipe 35c, a third flow rate control valve 18b provided in the steam supply pipe 18a, and the above-described steam generating means. ing.
The flow control valves 17b and 18b are connected to the control unit 29 and are controlled by the control unit 29.
Note that the configuration of the first humidifying unit 16 is not limited to this, and any configuration that can supply steam to the mixed gas G0 flowing in the first transport pipe 35a can be used. The same applies to the second humidifier 17 and the third humidifier 18.

The above-mentioned second humidity sensor 25 is attached to a portion of the second transport pipe 35b on the downstream side D2 from the portion where the second humidifying section 17 is attached. The second humidity sensor 25 detects a relative humidity of a first humidified non-permeable gas G5 described later.
The third humidity sensor 26 described above is attached to a portion of the third transport pipe 35c on the downstream side D2 from the portion where the third humidifying section 18 is attached. The third humidity sensor 26 detects a relative humidity of a second non-humidified gas G9 described later.
A fourth humidity sensor 27 and a gas exhaust pipe 40 are attached to the fourth transport pipe 35d. The fourth humidity sensor 27 detects a relative humidity of a third non-permeate gas G10 described later.
These humidity sensors 25, 26, and 27 are connected to the control unit 29 and transmit detection results to the control unit 29.

Although not shown, the control unit 29 has an arithmetic circuit, a memory, and the like. The memory stores a program and the like for controlling the arithmetic circuit.
The control unit 29 is connected to the temperature sensor 22 and the humidity sensors 24, 25, 26, and 27, and receives a detection result such as a temperature transmitted from the temperature sensor 22 or the like. The control unit 29 is connected to the flow control valves 16b, 17b, 18b and the temperature control unit 20. The control unit 29 adjusts the flow rate of the steam W supplied by the humidification units 16, 17, and 18. The control unit 29 controls the temperature of the mixed gas G0 by controlling the temperature control unit 20.

Next, the method for recovering carbon dioxide of the present embodiment will be described. FIG. 4 is a flowchart showing the carbon dioxide recovery method S of the present embodiment.
The mixed gas G0 is supplied from a power generation facility or the like to the gas separation membrane device 1 shown in FIG. At this time, the pressure of the mixed gas G0 is a pressure higher than the atmospheric pressure, for example, about 2 PMa (megapascal) to about 4 PMa. The temperature of the mixed gas G0 is several hundred degrees Celsius.
The mixed gas G0 supplied to the gas separation membrane device 1 is distributed to each gas separation membrane module 10.

First, in step S1 shown in FIG. 4, the control unit 29 sets the temperature of the mixed gas G0 supplied to the first gas separation membrane 45A, that is, the gas separation membrane element 11A, to 100 ° C. or less.
Specifically, the control unit 29 receives the temperature of the mixed gas G0 detected by the temperature sensor 22. Then, based on the received temperature, the temperature controller 20 adjusts the ability to cool the mixed gas G0. Then, the temperature of the mixed gas G0 detected by the temperature sensor 22 is adjusted to be 100 ° C. or less.

Next, in step S3, the relative humidity of the mixed gas G0 is detected by the first humidity sensor 24, and the relative humidity of the mixed gas G0 is adjusted to 50% or more and 80% or less.
Specifically, the water vapor W is supplied to the mixed gas G0 by adjusting the opening of the first flow rate control valve 16b of the first humidifying unit 16 based on the detection result of the first humidity sensor 24. . For example, when the detected relative humidity of the mixed gas G0 is 50%, the opening degree of the first flow control valve 16b is maximized, and when the detected relative humidity of the mixed gas G0 is 80%, the first flow control valve 16b is turned off. close.
At this time, it is preferable to make the relative humidity of the mixed gas G0 close to 80%.
In addition, a known dehumidifier may be provided in the first transport pipe 35a in case the relative humidity of the mixed gas G0 exceeds 80% when the temperature of the mixed gas G0 is cooled to 100 ° C. or less. In this case, the control unit 29 controls the dehumidifier to reduce the relative humidity of the mixed gas G0 to nearly 80%.

Next, in step S5, the mixed gas G0 is supplied to one surface 45A1 of the first gas separation membrane 45A of the gas separation membrane element 11A. Since the temperature of the mixed gas G0 is 100 ° C. or lower, the decomposition of the molecular structure of the polymer membrane is suppressed even if the first gas separation membrane 45A has a polymer membrane.
Of the mixed gas G0, the carbon dioxide gas G1 that has passed through the first gas separation membrane 45A is recovered through the suction hole 14a of the collection pipe 14, and is discharged from the end of the collection pipe 14 on the side of the first lid 36 to the outside. Conveyed. Not only the carbon dioxide gas G1 but also a small amount of water vapor W and hydrogen gas permeate the gas separation membrane element 11A.
No sweep gas is used for the gas separation membrane element 11A and the gas separation membrane elements 11B and 11C described later.
On the other hand, the first non-permeate gas (non-permeate gas) G2 of the mixed gas G0 that has not been permeated by the gas separation membrane element 11A (the first gas separation membrane 45A) is second from the gas separation membrane element 11A. It is transported to the transport pipe 35b.

Next, in step S7, water vapor W is supplied to the first non-permeate gas G2 before being supplied to the gas separation membrane element 11B (second gas separation membrane 45B) as shown in FIG. The humidified non-permeable gas (humidified non-permeable gas) G5. At this time, the amount of water vapor W supplied to the first non-permeable gas G2 is adjusted so that the relative humidity of the first humidified non-permeable gas G5 becomes 50% or more and 80% or less.
Specifically, the control unit 29 receives the humidity of the first humidified non-permeable gas G5 detected by the second humidity sensor 25. Then, based on the received humidity, the relative humidity of the first humidified non-permeable gas G5 is adjusted to 50% or more and 80% or less by adjusting the opening of the second flow rate control valve 17b of the second humidifying unit 17. Adjust so that Since the water vapor W permeates the gas separation membrane element 11A, the water vapor W is supplied in the second humidifier 17 as needed.

In order to increase the selectivity of the carbon dioxide gas in the first gas separation membrane 45A of the gas separation membrane element 11A, the relative humidity of the mixed gas G0 is set so that the relative humidity of the first non-permeate gas G2 becomes 50% or more. Preferably, the humidity is adjusted.
Since the first non-permeate gas G2 does not permeate the first gas separation membrane 45A, and more generally, the flow rate of the mixed gas G0 in the gas separation membrane element 11A is relatively slow, the first non-permeate gas G2 The pressure of G2 is hardly lower than the pressure of the mixed gas G0. For this reason, it is not necessary to increase the pressure of the first humidified non-permeate gas G5 by a pressure increasing means such as a compressor and then supply the gas to the gas separation membrane element 11B.

Next, in step S9, the first humidified non-permeate gas G5 is supplied to one surface 45B1 of the second gas separation membrane 45B of the gas separation membrane element 11B.
The carbon dioxide gas G1 that has passed through the gas separation membrane element 11B among the first humidified non-permeable gas G5 is recovered through the suction hole 14a of the collection pipe 14. In this case, the carbon dioxide gas G1 as the permeable gas is countercurrent to the first humidified non-permeable gas G5 as the supply gas. The flow direction of the carbon dioxide gas G1 inside is reversed.
On the other hand, of the first humidified non-permeate gas G5, the second non-permeate gas G6 not permeated by the gas separation membrane element 11B is transported from the gas separation membrane element 11B to the third transport pipe 35c.

Next, in step S11, as shown in FIG. 2, water vapor W is supplied to the second non-permeate gas G6 to form a second humidified non-permeate gas G9. At this time, the amount of water vapor W supplied to the second non-permeable gas G6 is adjusted so that the relative humidity of the second humidified non-permeable gas G9 is 50% or more and 80% or less.
Specifically, the control unit 29 receives the humidity of the second non-humidified gas G9 detected by the third humidity sensor 26. Then, based on the received humidity, the relative humidity of the second humidified non-permeable gas G9 is adjusted to 50% or more and 80% or less by adjusting the opening of the third flow rate control valve 18b of the third humidifying section 18. Adjust so that

Next, in Step S13, the second humidified non-permeable gas G9 is supplied to one surface of the third gas separation membrane of the gas separation membrane element 11C. Of the second humidified non-permeate gas G9, the carbon dioxide gas G1 that has passed through the third gas separation membrane is collected by the collection pipe 14.
On the other hand, of the second humidified non-permeate gas G9, the third non-permeate gas G10 not permeated by the third gas separation membrane is transported from the gas separation membrane element 11C to the fourth transport pipe 35d.
The humidity of the third non-permeate gas G10 detected by the fourth humidity sensor 27 is transmitted to the control unit 29. It is preferable that the relative humidity of the second humidified non-permeable gas G9 is set so that the relative humidity of the third non-permeable gas G10 becomes 50% or more.
The third non-permeate gas G10 is a gas from which most of the carbon dioxide gas G1 has been recovered. The third non-permeate gas G10 is conveyed to the outside from the gas discharge pipe 40 and exhausted.

  When the relative humidity is lower than 50%, it was confirmed that the permeation speed of the carbon dioxide gas permeating the gas separation membrane was sharply reduced (decreased by one digit or more). Therefore, the lower limit of the relative humidity was set to 50%. did. Further, if the relative humidity becomes too high, the water stagnates after passing through the gas separation membrane and starts to hinder the passage of carbon dioxide gas. Therefore, the upper limit of the relative humidity was set to 80%.

As described above, according to the carbon dioxide recovery method S of the present embodiment and the gas separation membrane module 10 using the series division method, when the mixed gas G0 is supplied to the first gas separation membrane 45A, the mixed gas G0 Is transmitted through the first gas separation membrane 45A, the relative humidity of the first non-permeable gas G2 is lower than the relative humidity of the mixed gas G0. In the first gas separation membrane 45A, when the relative humidity of the supplied gas is higher to some extent, the selectivity of carbon dioxide gas to hydrogen gas permeating the first gas separation membrane 45A is improved. By supplying water vapor W to the first non-permeable gas G2 to form the first humidified non-permeable gas G5, the relative humidity of the first humidified non-permeable gas G5 is compared with the relative humidity of the first non-permeable gas G2. Humidity increases.
Therefore, the carbon dioxide gas G1 can be efficiently recovered from the mixed gas G0 by the second gas separation membrane 45B.

The amount of the water vapor W supplied to the first non-permeable gas G2 is adjusted so that the relative humidity of the first humidified non-permeable gas G5 becomes 50% or more and 80% or less. Since the selectivity of the gas separation membrane is maximized when the relative humidity of the gas to be permeated is 50% or more and 80% or less, the carbon dioxide gas G1 can be more efficiently recovered from the mixed gas G0. it can.
By setting the temperature of the mixed gas G0 supplied to the first gas separation membrane 45A to 100 ° C. or less, even if the first gas separation membrane 45A has a polymer membrane, the molecular structure of the polymer membrane can be reduced. Decomposition can be suppressed.
After adjusting the relative humidity of the mixed gas G0 to 50% or more and 80% or less, the mixed gas G0 is supplied to the first gas separation membrane 45A. By increasing the selectivity of the gas separation membrane G0 in the first gas separation membrane 45A, the carbon dioxide gas G1 can be more efficiently recovered from the mixed gas G0 by the first gas separation membrane 45A.

The gas separation membrane module 10 of the present embodiment does not use a booster and a sweep gas. By setting the temperature of the mixed gas G0 to 100 ° C. or lower, a relatively inexpensive gas separation membrane having low heat resistance can be used. Thus, the gas separation membrane module 10 can be configured at a low cost by suppressing the energy input.
This gas separation membrane module is capable of efficiently and realistically permitting the permeated gas and non-permeated gas properties of high purity and high recovery required from a mixed gas with a simple system and a simple structure. It is possible to provide a method of recovering carbon dioxide and a gas separation membrane module that can be recovered at a reduced cost. Based on the spiral membrane system, it is possible to provide a structure and a system that stably supplies and holds water vapor gas necessary for performing high performance and stable carbon dioxide permeation phenomenon with low external input energy and low cost. it can.

The present gas separation membrane module is based on a spiral membrane system and includes the following means (1) to (3) as a gas separation system.
(1) A single-stage system and a series-division system instead of the conventional multistage system with halfway boosting or a single-stage / all-parallel system.
(2) The method of supplying water vapor to the gas separation membrane element is a method of supplying an appropriate water vapor-containing raw material gas to the membrane element for each element divided in series by a cross-flow method instead of a sweep method.
(3) Operating the membrane module and the membrane equipment / system including the supply gas and the gas separation membrane element at 100 ° C. or lower.
These proposals (1) to (3) provide a significant improvement over the conventional carbon dioxide separation technology. It is possible to secure a predetermined gas separation property and to provide a low-cost system more suitable for practical use.
Other features of the present gas separation membrane module include the following (4) to (6).
(4) Cost reduction and environmental improvement by minimizing the input of external energy such as electric power and steam.
(5) Cost reduction by reducing the film area.
(6) Simplification of the system and piping around the membrane module, improvement of operability, and cost reduction.

As described above, one embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and the configuration can be changed, combined, or deleted without departing from the gist of the present invention. Etc. are also included.
For example, in the embodiment, the gas separation membrane module 10 does not need to include the humidity sensors 24, 25, 26, and 27. In this case, the amounts of the steam W supplied from the humidifying units 16, 17, and 18 are obtained in advance by experiments, simulations, and the like, based on conditions such as the amount of the mixed gas G0 supplied and the temperature. Then, the steam W may be supplied from the humidifiers 16, 17, 18 by the determined supply amount.

  If it is known that the relative humidity of the mixed gas G0 supplied to the gas separation membrane device 1 is 50% or more and 80% or less, the gas separation membrane module 10 does not need to include the first humidifier 16. Good.

When it is known in advance that the temperature of the mixed gas G0 supplied to the gas separation membrane device 1 is 100 ° C. or less, the gas separation membrane module 10 does not need to include the temperature control unit 20. In this case, step S1 is not performed in the carbon dioxide recovery method S.
In the embodiment, the first gas separation membrane 45A is formed in a tubular shape so as to be wound. However, the shape of the first gas separation membrane is not particularly limited, and the first gas separation membrane may be a flat plate or a hollow fiber membrane. The same applies to the second gas separation membrane and the third gas separation membrane.

10 Gas separation membrane module 17 Second humidifier (humidifier)
Reference Signs List 20 temperature control unit 22 temperature sensor 25 second humidity sensor (humidity sensor)
29 control unit 35e transport unit 45A first gas separation membrane 45A1, 45B1 one surface 45B second gas separation membrane G0 mixed gas G1 carbon dioxide gas (permeated gas)
G2 First non-permeate gas (non-permeate gas)
G5 First humidified non-permeable gas (humidified non-permeable gas)
S CO2 recovery method W Steam

Claims (9)

A carbon dioxide recovery method for recovering carbon dioxide gas from a mixed gas containing carbon dioxide gas,
Collection tube suction holes are formed on the outer peripheral surface extends in a direction along the axis, first an the gas separation membrane of carbon dioxide gas is selectively permeable to ions of the mixed gas by the supply of water In a state where the gas separation membrane and the second gas separation membrane are provided so as to be wound around the outer peripheral surface of the collection tube at intervals in the direction along the axis,
The mixed gas is supplied to one surface of the first gas separation membrane, and the carbon dioxide gas permeated by the first gas separation membrane among the mixed gas is recovered from the suction hole into the collection pipe. While
By supplying water vapor to the non-permeate gas that has not been permeated by the first gas separation membrane of the mixed gas, to obtain a humidified non-permeate gas,
In that the said humidified non-permeate gas is supplied to one surface of the second gas separation membrane, recovering the carbon dioxide gas that is transmitted by the second gas separation membrane to the collecting pipe from the suction hole Characteristic carbon dioxide recovery method.   The method for recovering carbon dioxide according to claim 1, wherein the amount of the water vapor supplied to the non-permeable gas is adjusted so that the relative humidity of the humidified non-permeable gas is 50% or more and 80% or less. .   The method for recovering carbon dioxide according to claim 1, wherein the temperature of the mixed gas supplied to the first gas separation membrane is set to 100 ° C. or less.   2. The mixed gas is supplied to the first gas separation membrane after water vapor is supplied to the mixed gas to adjust the relative humidity of the mixed gas to 50% or more and 80% or less. The method for recovering carbon dioxide according to any one of claims 1 to 3.   The collection tube, the first gas separation membrane and the second gas separation membrane are arranged in a container body,
  When supplying the mixed gas to the first gas separation membrane, transport the mixed gas through a portion of the container body upstream of the first gas separation membrane,
  When supplying the humidified non-permeate gas to the second gas separation membrane, the humidified non-permeate gas is transported through a portion of the container body between the first gas separation membrane and the second gas separation membrane. The method for recovering carbon dioxide according to any one of claims 1 to 4, wherein: A gas separation membrane module for recovering carbon dioxide gas from a mixed gas containing carbon dioxide gas,
A collection tube extending in a direction along the axis and having a suction hole formed on the outer peripheral surface,
The collection tube, at intervals in a direction along said axis and provided so as to be wound around the outer peripheral surface of the collection tube, and ionizing the carbon dioxide gas in the mixed gas by the supply of water A first gas separation membrane and a second gas separation membrane that are selectively permeated and are gas separation membranes for recovering the carbon dioxide gas from the suction hole into the collection pipe .
The mixed gas is supplied to one surface of the first gas separation membrane, and the non-permeated gas of the mixed gas that is not permeated by the first gas separation membrane is transported, and the second gas separation membrane is provided. A transport unit that supplies the non-permeate gas to one surface of the
A humidifying unit that supplies water vapor to the non-permeating gas before being supplied to the second gas separation membrane and is a humidified non-permeating gas,
A gas separation membrane module comprising: A humidity sensor for detecting a relative humidity of the humidified non-permeating gas,
A control unit that adjusts the flow rate of the steam supplied by the humidifying unit,
With
7. The controller according to claim 6 , wherein the controller adjusts the relative humidity of the non-humidified gas to be 50% or more and 80% or less by the humidifier based on a detection result of the humidity sensor. 8. Gas separation membrane module. A temperature adjusting unit that adjusts the temperature of the mixed gas that the transporting unit supplies to the first gas separation membrane,
A temperature sensor that detects the temperature of the mixed gas that the transfer unit is supplying to the first gas separation membrane,
A control unit for adjusting the temperature of the mixed gas,
With
Wherein, based on a detection result of said temperature sensor, gas separation according to claim 6 or 7 the temperature of the mixed gas by the temperature control unit and adjusting to be 100 ° C. or less Membrane module.   The collection tube, the first gas separation membrane and the second gas separation membrane comprising a container body disposed therein,
  The transport unit, a portion of the container body upstream of the first gas separation membrane, and a portion between the first gas separation membrane and the second gas separation membrane in the container body, The gas separation membrane module according to any one of claims 6 to 8, comprising:

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