JP6468995B2 - Gas separation method and equipment by pressure swing adsorption method - Google Patents

Gas separation method and equipment by pressure swing adsorption method Download PDF

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JP6468995B2
JP6468995B2 JP2015240723A JP2015240723A JP6468995B2 JP 6468995 B2 JP6468995 B2 JP 6468995B2 JP 2015240723 A JP2015240723 A JP 2015240723A JP 2015240723 A JP2015240723 A JP 2015240723A JP 6468995 B2 JP6468995 B2 JP 6468995B2
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gas
adsorption
cleaning
adsorption tower
adsorbent packed
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JP2017104808A (en
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伸行 紫垣
伸行 紫垣
茂木 康弘
康弘 茂木
たかし 原岡
たかし 原岡
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Jfeスチール株式会社
新日鐵住金株式会社
新日鉄住金エンジニアリング株式会社
株式会社神戸製鋼所
日新製鋼株式会社
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  The present invention relates to a gas separation method and a gas separation facility for separating and recovering a specific gas component from a raw material gas (mixed gas) by a pressure swing adsorption method (for example, separating and recovering carbon dioxide gas from an ironworks byproduct gas). Is.

  Conventionally, a pressure swing adsorption method (hereinafter referred to as PSA method) has been widely used as a method for separating and recovering a specific gas component contained in a source gas (mixed gas) (for example, Patent Document 1). The PSA method is a separation method that utilizes the fact that the amount of gas component adsorbed on the adsorbent varies depending on the gas species and its partial pressure, and a process for adsorbing a specific gas component on the adsorbent (adsorption process), A step of increasing the adsorption rate of the specific gas component (cleaning step), and a step of desorbing the adsorbed specific gas component from the adsorbent and recovering the gas (desorption step). Although this PSA method is applied to various fields, it is often used as a method for producing a high-concentration gas by adsorbing one component contained in a raw material gas. For example, chemical raw materials and carbon dioxide gas for dry ice are produced by the PSA method using boiler exhaust gas or combustion exhaust gas as raw material gas.

FIG. 10 shows a conventional facility for separating and recovering carbon dioxide gas (CO 2 ) from raw material gas by the PSA method. The PSA facility 30 includes three adsorption towers 41 to 43, and the adsorption towers 41 to 43 are filled with an adsorbent (for example, zeolite). Here, a method for separating and recovering CO 2 from a raw material gas (for example, blast furnace gas) will be described assuming that the adsorption tower 41 is performing an adsorption process, the adsorption tower 42 is performing a washing process, and the adsorption tower 43 is performing a desorption process. . In the drawing, V 1 to V 12 are open / close valves provided in the gas pipe, and the white valves indicate the open state and the black valves indicate the closed state.

In the adsorption tower 41 in which the adsorption process is performed, the valves V 1 and V 4 are opened, and the raw material gas C 0 is introduced through the raw material gas introduction pipe 44 by the blower 45. In the raw material gas C 0 , CO 2 is adsorbed by the adsorbent in the adsorption tower 41, and the off gas C 1 is discharged through the off gas exhaust pipe 47. At this stage, CO 2 is concentrated in the adsorption tower 41, but generally a sufficient concentration is not obtained. In the adsorption tower 43 in which the desorption process is performed, the valve V 11 is opened, the adsorbed CO 2 is desorbed from the adsorbent, and the concentrated CO 2 (gas C 2 ) is discharged by the vacuum pump 46. . Part of this high-concentration CO 2 (gas C 2 ) is discharged as a recovery gas C 3 through a recovery gas exhaust pipe 48, and the rest is used as a cleaning gas C 4 by a cleaning gas supply pipe 49 in the cleaning process. To be introduced. In the adsorption tower 42 in the cleaning process, the valves V 6 and V 8 are opened, the cleaning gas C 4 is introduced into the tower, and unnecessary gas components in the adsorption tower are discharged from the off-gas exhaust pipe 47 as off-gas C 5. Is done. By this washing step, gas components other than CO 2 remaining in a small amount are desorbed from the adsorbent and discharged from the adsorption tower 42, whereby high-concentration CO 2 remains in the adsorption tower 42. become. Each adsorption tower sequentially performs the above-described adsorption process, washing process, and desorption process, whereby high-concentration CO 2 can be continuously separated and recovered from the source gas C 0 as the recovery gas C 3 .

JP 2012-250215 A

Since power required for gas separation is large in the PSA method, it is necessary to reduce power consumption in the PSA in order to reduce the gas separation cost. In particular, when CO 2 is separated and recovered from the ironworks byproduct gas, the ironworks byproduct gas has a low CO 2 concentration (for example, about 22 vol% in the blast furnace gas), so that power consumption required for CO 2 separation is large. However, in the PSA facility using the conventional adsorption tower as shown in FIG. 10, it is difficult to reduce the power consumption because there are restrictions on the gas distribution method.

That is, when a multi-component mixed gas such as blast furnace gas is used as a raw material gas, the gas composition changes in the process of flowing the gas through the adsorbent packed bed, so the gas adsorption state on the adsorbent is not uniform. In particular, in the upper region of the adsorbent packed bed, the off-gas with a small amount of CO 2 after flowing through the lower region flows, so that the CO 2 adsorption amount decreases. Further, since the CO 2 is adsorbed in the lower region of the adsorbent filling layer, since the partial pressure of CO 2 other than the gas component in the off-gas (N 2, CO, etc.) is increased, other than CO 2 in the upper region The adsorption amount of the gas component increases, and the recovered CO 2 purity in the region decreases. Thus, in the conventional adsorption tower, due to the essential restrictions on the gas flowing through the adsorbent packed bed, the distribution of CO 2 adsorption amount and recovered CO 2 purity is inevitably generated in the adsorbent packed bed, For this reason, it is difficult to perform efficient gas separation and recovery with low power consumption.

  Accordingly, an object of the present invention is to provide a gas separation method and equipment capable of solving the above-described problems of the prior art and increasing the separation and recovery amount of the target gas component in the gas separation by the pressure swing adsorption method. is there. A further object of the present invention is to provide a gas separation method and equipment capable of efficiently performing gas separation by the pressure swing adsorption method with low power consumption.

The gist of the present invention for solving the above problems is as follows.
[1] In a gas separation facility for separating and recovering a specific gas component from a raw material gas by a pressure swing adsorption method, a plurality of components are provided between a gas inlet (1) at the bottom of the tower and a gas outlet (2) at the top of the tower. The adsorbent packed bed (3) is provided in series with the space (4) not filled with the adsorbent, and the gas inlet / outlet (5) for introducing or discharging gas from the space (4) is provided. A gas channel (B) communicating with a tower (A), a gas inlet part (1), a gas outlet part (2) and a gas inlet / outlet (5) of the adsorption tower (A), the gas channel (B) By switching the flow path with a plurality of on-off valves (6) provided in the gas, one or more adsorbent packed beds (3) can be bypassed to allow gas to flow through the adsorption tower (A). Gas separation equipment by pressure swing adsorption method.

[2] In the gas separation facility of [1], the gas flow path (B) includes a gas pipe (7) connected to the gas inlet part (1) and a gas pipe connected to the gas outlet part (2). (8), one end connected to the gas pipe (7) (11) and the other end connected to the gas pipe (8) (12), and one end connected to the gas inlet ( 5) Gas separation equipment by pressure swing adsorption method, characterized in that it has a gas pipe (10) connected to (13) in the middle of the gas pipe (9).

[3] In a gas separation method for separating and recovering a specific gas component from a raw material gas by a pressure swing adsorption method, the gas separation facility of [1] or [2] is used, and one or more raw material gases or cleaning gases are used. A gas separation method by a pressure swing adsorption method, wherein the adsorbent packed bed (3) is bypassed and circulated in the adsorption tower (A).
[4] In the gas separation method of the above [3], one or more adsorbent packed beds (only in a part of time zone) during one step of flowing the raw material gas or the cleaning gas into the adsorption tower (A) ( 3) A gas separation method by a pressure swing adsorption method, wherein the raw material gas or the cleaning gas is circulated in the adsorption tower (A) by bypassing 3).

[5] In the gas separation method of [3] or [4] above, an adsorbent packed bed that bypasses the source gas or the cleaning gas during one step of circulating the source gas or the cleaning gas into the adsorption tower (A) ( (3) A gas separation method by a pressure swing adsorption method, wherein the method is changed.
[6] In the gas separation method of the above [5], the raw material gas or the cleaning gas is circulated to all the adsorbent packed beds (3) in the adsorption tower (A) before the process is completed. A gas separation method by a pressure swing adsorption method.

According to the present invention, a plurality of adsorbent packed beds (3) are provided in multiple stages in the adsorption tower (A), and the raw material gas or the cleaning gas bypasses one or more arbitrary adsorbent packed beds (3). The adsorbent tower (A) can be circulated in the adsorption tower (A) by appropriately selecting and changing the adsorbent packed bed (3) through which the raw material gas or the cleaning gas is circulated in one process. It is possible to prevent the gas adsorption amount and the recovered gas purity from being distributed over the entire adsorbent packed bed. For this reason, gas separation by the pressure swing adsorption method can be performed efficiently, and the recovery amount of the target gas component can be increased.
Furthermore, gas separation by the pressure swing adsorption method can be efficiently performed with a small amount of power consumption, and the effect is particularly great when the method of the present invention is applied to a cleaning process. Thereby, for example, in the separation and recovery of carbon dioxide gas in a steelworks byproduct gas, it is possible to increase the amount of carbon dioxide gas recovered and reduce the power consumption required for recovery.

Explanatory drawing which shows one Embodiment of the gas separation equipment of this invention Explanatory drawing which shows other embodiment of the gas separation equipment of this invention. Explanatory drawing which shows other embodiment of the gas separation equipment of this invention. Explanatory drawing which shows one Embodiment of this invention method using the gas separation installation of FIG. Explanatory drawing which shows other embodiment of this invention method using the gas separation installation of FIG. Explanatory drawing which shows one Embodiment of this invention method using the gas separation installation of FIG. Explanatory drawing which shows other embodiment of this invention method using the gas separation installation of FIG. Explanatory drawing which shows other embodiment of this invention method using the gas separation installation of FIG. In an Example, the graph which shows the result of having measured the CO density | concentration of the off gas in a washing | cleaning process Explanatory drawing which shows an example of the gas separation equipment by the conventional pressure swing adsorption method

The gas separation facility of the present invention is a gas separation facility for separating and recovering a specific gas component (target gas component) from a raw material gas (mixed gas) by a pressure swing adsorption method.
FIG. 1 shows an embodiment of a gas separation facility according to the present invention. The gas separation facility includes an adsorption tower A and a gas flow path B for introducing and discharging the gas from the adsorption tower A. Usually, a plurality of adsorption towers A (generally three or more) are provided, and the adsorption process, washing process, and desorption process are sequentially performed in the plurality of adsorption towers A, and each of the above processes is always performed in any of the adsorption towers A. To be done.

A gas inlet portion 1 is provided at the lower end of the adsorption tower A, and a gas outlet portion 2 is provided at the upper end. Between the gas inlet portion 1 and the gas outlet portion 2, a plurality of adsorbent packed layers 3 are provided. It is provided in series (multi-stage) with a space 4 not filled with the adsorbent interposed therebetween. In this embodiment, two adsorbent packed layers 3 a and 3 b are provided. Between the adsorbent packed layers 3 a and 3 b , a gas inlet / outlet 5 for introducing or discharging gas from the space 4 is provided.
In addition, each adsorbent packed bed 3 is filled with an adsorbent between partition walls (not shown) having air permeability such as a net-like member, and the adsorbent packed bed passes through the partition walls. Gas circulates.

The gas pipe constituting the gas flow path B is connected to the gas inlet part 1, the gas outlet part 2 and the gas inlet / outlet 5 of the adsorption tower A, and the gas flow path B communicates with these gas inlets and outlets. On-off valves 6 are provided at essential points (plural places) of the gas flow path B, and one or more arbitrary adsorbent packed layers 3 (in this embodiment, filled with adsorbents) are switched by switching the flow paths by the open / close valves 6. Any one of the layer 3 a and the adsorbent packed layer 3 b ) is bypassed so that the gas can be circulated in the adsorption tower A.

Specifically, the gas flow path B includes a gas pipe 7 connected to the gas inlet part 1, a gas pipe 8 connected to the gas outlet part 2, and one end 11 connected in the middle of the gas pipe 7. The gas pipe 9 is connected to the gas pipe 8 at one end and connected to the gas inlet / outlet 5 at one end, and the gas pipe 10 is connected to the gas pipe 9 at the other end. The on-off valve 6 a in the pipe portion 70 between the gas inlet 1 and the connecting portion 11 of the gas pipe 7, on-off valve 6 b in the pipe portion 80 between the connection portions 12 and the gas outlet portion 2 of the gas piping 8 However, the opening / closing valve 6c is provided in the piping portion 90 between the connecting portion 11 and the connecting portion 13 in the gas piping 9, and the opening / closing valve 6d is provided in the piping portion 91 between the connecting portion 12 and the connecting portion 13 in the gas piping 9. Each is provided.

According to such a configuration, the gas is circulated in the adsorption tower A by bypassing the adsorbent packed bed 3 a or the adsorbent packed bed 3 b by switching the flow path by opening and closing the on-off valves 6 a to 6 d . be able to.
Although not shown, the gas pipe 7 is branched into a plurality of branch pipes, and one of the branch pipes is connected to a source gas supply system, as in the gas flow path of FIG. The other branch pipe leads to the gas piping of the other adsorption tower A so that the desorption gas desorbed in the other adsorption tower A can be supplied as a cleaning gas. This configuration is the same in the embodiments of FIGS.

There is no particular restriction on the number of adsorbent packed layers 3 provided in the adsorption tower A. However, if the number of layers is large, design restrictions such as the arrangement of on-off valves and piping layout increase. Is appropriate.
FIG. 2 shows an embodiment in which four adsorbent packed layers 3 are provided in the gas separation facility of the present invention.
Between the gas inlet part 1 and the gas outlet part 2 of the adsorption tower A, four layers of adsorbent packed layers 3 A to 3 D interpose spaces 4 A to 4 C not filled with the adsorbent. In series (multistage). Between adsorbent filling layer 3 adjacent the gas inlet and outlet 5 A to 5 C for introducing or discharging a gas are provided from each of the space portions 4 A to 4 C.

In the present embodiment, the gas pipe constituting a gas flow path B is connected to the gas inlet 1 and the gas outlet 2 and the gas inlet and outlet 5 A to 5 C of the adsorption tower A, the entrance of the gas flow path B these gases It communicates with. On-off valves 6 are provided at essential points (plural places) of the gas flow path B, and one or more arbitrary adsorbent packed layers 3 (for example, adsorbent packed layers 3) are switched by switching the flow paths by the open / close valves 6. one of a to 3 D, or adsorbent filling layer 3 a +3 B, the adsorbent packed layer 3 a +3 B +3 C, the gas in the adsorbent filling layer 3 C +3 D, etc.) pass to the adsorption tower a to It can be distributed.

The gas pipe constituting the gas flow path B includes a gas pipe 7 connected to the gas inlet part 1, a gas pipe 8 connected to the gas outlet part 2, one end connected 11 in the middle of the gas pipe 7, and the other end The gas pipe 9 connected 12 in the middle of the gas pipe 8 is the same as in the embodiment of FIG. Gas flow path B of this embodiment further has one end connected to the gas inlet and outlet 5 A, a gas pipe 10 A connected 14 has been in the middle of the other end the gas pipe 9, one end is connected to the gas inlet and outlet 5 B has a gas pipe 10 B connected 15 to the middle of the other end the gas pipe 9, one end is connected to the gas inlet and outlet 5 C, the other end of the middle connected 16 gas pipe 10 C of the gas pipe 9 ing. An on-off valve 6 A is provided in a pipe portion 70 between the gas inlet portion 1 and the connecting portion 11 in the gas pipe 7, and an on-off valve 6 B is provided in a pipe portion 80 between the gas outlet portion 2 and the connecting portion 12 in the gas pipe 8. but off valve 6 C the pipe portion 92 between the connection portions 11 and the connecting portion 14 of the gas pipe 9, the on-off valve 6 D to the pipe portion 93 between the connection portions 14 and the connecting portion 15 of the gas pipe 9, off valve 6 E to the pipe portion 94 between the connection portions 16 and the connecting portion 15 of the gas pipe 9, the on-off valve 6 F in piping 95 between the connection portions 12 and the connecting portion 16 of the gas pipe 9, the gas pipe 10 on-off valve 6 G to a is on-off valve 6 H in the gas pipe 10 B is on-off valve 6 I in gas piping 10 C are respectively provided.
According to such a configuration, the gas can be circulated in the adsorption tower A by bypassing the one or more adsorbent packed beds 3 by switching the flow paths by opening and closing the on-off valves 6 A to 6 I.

FIG. 3 shows an embodiment in which three adsorbent packed layers 3 are provided in the gas separation facility of the present invention.
Between the gas inlet 1 and the gas outlet portion 2 of the adsorption tower A, the adsorbent packed layer 3 E to 3 G of three layers, is interposed between the space portion 4 D, 4 E adsorbent is not filled In series (multistage). Between adsorbent filling layer 3 adjacent each of the space 4 D, 4 gas inlet and outlet for introducing and discharging the gas from E 5 D, 5 E is provided.

In the present embodiment, the gas pipe constituting the gas passage B, the adsorption tower gas inlet portion of the A 1 and the gas outlet is connected to two gas entrance 5 D, 5 E, the gas flow path B is entrance of these gases It communicates with. On-off valves 6 are provided at essential points (plural places) of the gas flow path B, and one or more arbitrary adsorbent packed layers 3 (for example, adsorbent packed layers 3) are switched by switching the flow paths by the open / close valves 6. Any of E to 3 G , or the adsorbent packed bed 3 E +3 F , the adsorbent packed bed 3 F +3 G ) is bypassed so that the gas can be circulated in the adsorption tower A.

The gas pipe constituting the gas flow path B includes a gas pipe 7 connected to the gas inlet part 1, a gas pipe 8 connected to the gas outlet part 2, one end connected 11 in the middle of the gas pipe 7, and the other end The gas pipe 9 connected 12 in the middle of the gas pipe 8 is the same as in the embodiment of FIG. Gas flow path B of this embodiment further has one end connected to the gas inlet and outlet 5 D, the gas pipe 10 D connected 17 to the middle of the other end the gas pipe 9, one end is connected to the gas entrance 5 E and the other end has a connection 18 to the gas pipe 10 E in the middle of the gas pipe 9. An opening / closing valve 6 J is provided in a piping portion 70 between the gas inlet portion 1 and the connecting portion 11 in the gas piping 7, and an opening / closing valve 6 K is provided in a piping portion 80 between the gas outlet portion 2 and the connecting portion 12 in the gas piping 8. but off valve 6 L on the pipe portion 96 between the connection portions 11 and the connecting portion 17 of the gas pipe 9, the on-off valve 6 M in the pipe portion 97 between the connection portions 17 and the connecting portion 18 of the gas pipe 9, off valve 6 N to the pipe portion 98 between the connection portions 18 and the connecting portion 12 of the gas pipe 9, on-off valve 6 O in the gas pipe 10 D is, on-off valve 6 P in the gas pipe 10 E is provided, respectively Yes.
According to such a configuration, the gas can be circulated in the adsorption tower A by bypassing one or more arbitrary adsorbent packed beds 3 by switching the flow path by opening and closing the on-off valves 6 J to 6 P. it can.

Next, the gas separation method of the present invention will be described.
The gas separation method of the present invention is a gas separation method for separating and recovering a specific gas component (target gas component) from a raw material gas by a pressure swing adsorption method. The gas is circulated in the adsorption tower A by bypassing the one or more adsorbent packed beds 3. Hereinafter, a case where CO 2 is separated and recovered from the raw material gas will be described as an example. For convenience, illustration of most of the gas flow path B including the on-off valve 6 is omitted in FIGS.

4 and 5 each show an embodiment of the method of the present invention using the gas separation facility of FIG. 1, and the broken line shows a gas path.
In the embodiment of FIG. 4, the on-off valve 6 a and the on-off valve 6 d of FIG. 1 are closed, the on-off valve 6 b and the on-off valve 6 c are opened, and the gas (raw material gas or cleaning gas) is filled with the lower adsorbent. and it is circulated only in the upper part of the adsorbent filling layer 3 b bypassing the layers 3 a.
In the embodiment of FIG. 5, the on-off valve 6 b and the on-off valve 6 c of FIG. 1 are closed, the on-off valve 6 a and the on-off valve 6 d are opened, and gas (raw material gas or cleaning gas) is adsorbed in the upper stage. The adsorbent packed bed 3 b is bypassed and is circulated only to the lower adsorbent packed bed 3 a .

FIG. 6 shows an embodiment of the method of the present invention using the gas separation facility of FIG. 2, and in this case, a solid line and a broken line show gas paths that circulate in different embodiments, respectively. .
In the solid line embodiment, the on-off valve 6 B , on-off valve 6 C , on-off valve 6 D , on-off valve 6 G , on-off valve 6 I in FIG. 2 is closed, on-off valve 6 A , on-off valve 6 H , on-off valve 6 E , and the on-off valve 6 F in the open, the gas (raw material gas or cleaning gas) of upper two adsorbent filling layer 3 C, 3 bypassing the D and the adsorbent packed layer 3 of the lower two stages a, 3 B It is distributed only to.
2, the on-off valve 6 A , on-off valve 6 G , on-off valve 6 H , on-off valve 6 F are closed, on-off valve 6 C , on-off valve 6 D , on-off valve 6 E , on-off valve 6 I, and the on-off valve 6 B to open, the gas (raw material gas or cleaning gas) flow only to the adsorbent filling layer 3 D the uppermost bypassing the adsorbent filling layer 3 a to 3 C except uppermost I am letting.
The gas to be circulated in the adsorption tower A in the method of the present invention is desorbed in the raw material gas in the adsorption step (the raw material gas for which the specific gas component is to be adsorbed and separated) or in the cleaning step (in the desorption step of the other adsorption tower) Part of the desorption gas).

As described above, when a multi-component mixed gas such as blast furnace gas is used as the raw material gas, the gas composition changes during the flow of gas through the adsorbent packed bed, so the gas adsorption state on the adsorbent is uniform. It will not be. In a conventional adsorption tower having a single adsorbent packed bed, particularly in the upper region of the adsorbent packed bed, the off-gas with less CO 2 after flowing through the lower region flows, so the CO 2 adsorption amount decreases. Further, since the CO 2 is adsorbed in the lower region of the adsorbent filling layer, since the partial pressure of CO 2 other than the gas component in the off-gas (N 2, CO, etc.) is increased, other than CO 2 in the upper region The adsorption amount of the gas component increases, and the recovered CO 2 purity in the region decreases. Thus, in the conventional adsorption tower, due to the essential restrictions on the gas flowing through the adsorbent packed bed, the distribution of CO 2 adsorption amount and recovered CO 2 purity is inevitably generated in the adsorbent packed bed, For this reason, it is difficult to perform efficient gas separation and recovery with low power consumption.

On the other hand, according to the present invention, for example, the following methods (i) and (ii) can be adopted, and the above-mentioned problems of the prior art can be solved.
(I) During one process of circulating the raw material gas or the cleaning gas into the adsorption tower A, the raw material gas or the adsorption gas A is bypassed in the adsorption tower A by bypassing one or more adsorbent packed beds 3 only in a part of the time zone. The cleaning gas is circulated, and the raw material gas or the cleaning gas is circulated through all the adsorbent packed beds 3 in the adsorption tower A in other time zones. When the raw material gas or the cleaning gas is circulated through the adsorbent packed bed 3, the CO 2 in the gas is adsorbed by the adsorbent. However, when the gas circulation time becomes long, the CO 2 adsorption amount becomes close to the equilibrium adsorption amount, Of CO 2 is not adsorbed by the adsorbent. Even if the gas is circulated through the adsorbent packed bed 3 in such a situation, only an unnecessary pressure loss is generated, and it does not contribute to an increase in the CO 2 adsorption amount. Therefore, by changing the gas flow path according to the time, the gas flow can be promoted and the adsorbent can adsorb CO 2 more efficiently. In addition, since the raw gas having a high CO 2 concentration can be introduced as it is into the upper region of the adsorption tower where the CO 2 adsorption amount is small in the conventional adsorption tower, more CO 2 is adsorbed in the upper region of the adsorption tower. Can do.

(Ii) During one step of flowing the raw material gas or the cleaning gas into the adsorption tower A, the adsorbent packed bed 3 for bypassing the raw material gas or the cleaning gas is changed. In this case, the raw material gas or the cleaning gas can be circulated to all the adsorbent packed beds 3 in the adsorption tower A by the end of the process. The reason for adopting the method (ii) is basically the same as the reason for the method (i).
The above methods (i) and (ii) can be performed in combination. That is, in the above (i), when one or more adsorbent packed beds 3 are bypassed and the source gas or the cleaning gas is circulated in the adsorption tower A, the adsorbent packing for bypassing the source gas or the cleaning gas in the meantime. Layer 3 can be changed.

FIG. 7 shows one embodiment of the above method (i) using the gas separation facility of FIG. 1, and the solid line and the broken line each show the path of gas flowing in a certain time zone. In this embodiment, in one process (adsorption process or washing process) in which the same gas is circulated in the adsorption tower A, for example, the entire adsorption in the adsorption tower A as shown by a solid line in 50 seconds out of a process time of 100 seconds. Gas is passed through the adsorbent packed bed 3 (adsorbent packed beds 3 a , 3 b ), and in the remaining 50 seconds, the lower adsorbent packed bed 3 a is bypassed as shown by the broken line, and the upper adsorbent packed bed 3 b is bypassed. Only circulate gas.

As described above, in a conventional adsorption tower having a single adsorbent packed bed, the upper adsorbent packed bed has a lower CO 2 adsorption amount than the lower adsorbent packed bed, and recovered CO 2. purity decreases, but the method of FIG. 7, the distribution part of the time zone step, the gas only lower adsorbent filling layer 3 a bypass to the upper adsorbent filling layer 3 b as a dashed line since thereby, to prevent the CO 2 adsorption amount and recovering CO 2 purity of the upper adsorbent filling layer 3 b is lower than the lower adsorbent filling layer 3 a, the CO 2 adsorption amount distribution in the adsorption tower It can be made more uniform.

In the method (i) using the gas separation facility shown in FIG. 2, for example, gas is first circulated through all the adsorbent packed beds 3 in the adsorption tower A, and the adsorbent packed bed on the lower stage from the middle. By bypassing 3 A and 3 B , gas is circulated only to the adsorbent packed layers 3 C and 3 D on the upper stage side. Alternatively, the gas is first circulated through all the adsorbent packed beds 3 in the adsorption tower A, and the gas is circulated to the upper adsorbent packed bed by bypassing the lower adsorbent packed layer from the middle. At this time, the number of adsorbent packed layers for bypassing the gas is sequentially increased from the lower side. That is, first, the adsorbent packed layer 3 A and bypassing adsorbent filling layer 3 B, 3 C, 3 is circulated gas only D, then the adsorbent packed layer 3 A, 3 B a bypass to the adsorbent The gas is circulated only through the packed beds 3 C and 3 D , and then the gas is circulated only through the adsorbent packed bed 3 D , bypassing the adsorbent packed beds 3 A , 3 B and 3 C.
In the method (i) using the gas separation facility of FIG. 3, for example, gas is first circulated through all the adsorbent packed beds 3 in the adsorption tower A, and the lower adsorbent packed bed 3 is halfway through. E is bypassed, gas is circulated only through the middle and upper adsorbent packed beds 3 F and 3 G , and then the lower and middle adsorbent packed beds 3 E and 3 F are bypassed, and the upper adsorbent packed bed 3 Gas is distributed only to G.

FIG. 8 shows an embodiment of the above method (ii) using the gas separation facility of FIG. 1, and the solid line and the broken line show the paths of gas flowing in a certain time zone. In this embodiment, in one process (adsorption process or washing process) for circulating the same gas into the adsorption tower A, for example, the upper adsorbent packed bed 3 b as shown by a solid line in 50 seconds out of a process time of 100 seconds. the bypassing is circulated gas only in the lower part of the adsorbent filling layer 3 a, only the remaining upper adsorbent filling layer 3 b bypassing the lower adsorbent filling layer 3 a as shown by a broken line in 50 seconds Circulate gas. Thus, by circulating the gas for each adsorbent packed bed, it is possible to prevent the purity of CO 2 adsorbed in the upper region of the adsorption tower from being lowered by the off-gas having a high impurity concentration. That is, this method is a particularly effective method for preventing contamination of the upper region of the adsorption tower by the cleaning off gas (gas having a high impurity concentration) in the cleaning process.

In the method (ii) described above using a gas separation equipment 2, for example, the adsorbent packed layer 3 A to 3 circulating gas, one in the order with respect to D (the other three adsorbent filling layer 3 may be bypassed), or gas may be circulated only through the adsorbent packed layers 3 A and 3 B by first bypassing the adsorbent packed layers 3 C and 3 D , and then filled with the adsorbent. Bypassing the layers 3 A and 3 D , gas is circulated only in the adsorbent packed layers 3 B and 3 C , and then bypassing the adsorbent packed layers 3 A and 3 B , the adsorbent packed layers 3 C and 3 D The gas may be circulated only in the adsorbent, and finally the adsorbent packed bed 3 A , 3 B , 3 C may be bypassed and the gas may be circulated only in the adsorbent packed bed 3 D.

In the method (ii) described above using a gas separation equipment of Figure 3, for example, the adsorbent packed layer 3 E to 3 2 adsorbents packed layer one by one for circulating the gas in the order (other against G 3 may be bypassed), or the gas is first circulated only in the adsorbent packed layers 3 E and 3 F by bypassing the adsorbent packed layer 3 G , and then the adsorbent packed layer 3 E The gas is circulated only in the adsorbent packed layers 3 F and 3 G , and finally the gas is circulated only in the adsorbent packed layer 3 G by bypassing the adsorbent packed layers 3 E and 3 F. May be.

Therefore, by adopting the above method (i) or / and (ii), it is possible to prevent the distribution of the CO 2 adsorption amount and the recovered CO 2 purity in the entire adsorbent packed bed, and the gas separation by the pressure swing adsorption method. Can be efficiently performed with low power consumption. For this reason, it is possible to increase the CO 2 recovery amount and reduce the power consumption required for the recovery.
7 and 8 is determined based on an off-gas composition (impurity concentration) analyzed by, for example, an infrared continuous gas analyzer or the like. The same applies to the case where the above-described methods (i) and (ii) are adopted using the gas separation facilities shown in FIGS.
Here, when the gas is circulated by bypassing a part of the adsorbent packed bed by the above methods (i) and (ii), the lower adsorbent packed bed is bypassed in the adsorption process, and the upper stage is washed in the cleaning process. The operation of bypassing the adsorbent packed bed is particularly effective.

The method of the present invention is most effective when a bypass operation is performed in the cleaning process (an operation in which a part of the adsorbent packed bed is bypassed and gas is circulated). In particular, the power consumption is reduced. It is effective. Therefore, from the viewpoint of the effect of the invention, it is more preferable to perform the bypass operation in the cleaning process or perform the bypass operation in both the adsorption process and the cleaning process.
The present invention can be used for separating and recovering a specific gas component (target gas component) from various source gases, and in particular, a facility for separating and recovering carbon dioxide gas in a steelworks byproduct gas (eg, blast furnace gas) and It is useful as a separation and recovery method, and enables an increase in the amount of carbon dioxide gas recovered and a reduction in power consumption required for recovery.

A demonstration test for separating and recovering CO 2 from blast furnace gas, which is a raw material gas, was performed using a PSA test apparatus (equipment including three adsorption towers A) having a configuration as shown in FIG. The adsorption tower A includes upper and lower two-stage adsorbent packed layers 3 a and 3 b, and has an inner diameter of 600 mm and an adsorbent packed layer thickness of 655 mm (× 2 stages). As the adsorbent, 240 kg / column of 13X zeolite which is a CO 2 adsorbent was used.
The test conditions were an adsorption pressure of 50 kPaG, a desorption pressure of -95 kPaG, a cycle time of 300 seconds, a recovered CO 2 concentration of 90 vol%, and a test was conducted with the gas flow form as shown in Table 1 to recover the recovered CO 2 amount and vacuum. The pump power intensity was evaluated. The results are shown in Table 1. In addition, although the implementation time of the adsorption process, the cleaning process, and the desorption process was 100 seconds each, in Table 1 and the following description, it is shown as the time in the implementation time (0 to 300 seconds) throughout the entire process. .

In Invention Example 1, in the adsorption step (0 to 100 seconds), first, the raw material gas was circulated through the lower and upper adsorbent packed beds 3 a and 3 b, and after 70 seconds from the start, the lower gas as shown in FIG. The adsorbent packed bed 3a was bypassed, and the source gas was circulated only to the upper adsorbent packed bed 3b .
In Invention Example 2, similarly to Invention Example 1, in the adsorption step (0 to 100 seconds), first, the raw material gas was circulated through the lower and upper adsorbent packed layers 3 a and 3 b, and after 70 seconds from the start, As shown in FIG. 4, the lower adsorbent packed bed 3a was bypassed, and the raw material gas was circulated only in the upper adsorbent packed bed 3b . Further, in the cleaning step (100 to 200 seconds), and the upper adsorbent filling layer 3 b by bypassed by flowing a raw material gas only in the lower part of the adsorbent filling layer 3 a as shown in FIG. 5 from the beginning.
In Comparative Example, since those that does not perform the bypass of gas to 3 b adsorbent filling layer 3 a or adsorbent filling layer at any step, using conventional adsorption tower with a single adsorbent filling layer It corresponds to the case.

According to Table 1, the inventive examples 1 and 2 have increased CO 2 recovery compared to the comparative example. In addition, among Invention Examples, Invention Example 2 in which the upper adsorbent packed bed is bypassed in the cleaning process has a reduced vacuum pump power consumption rate as compared with the Comparative Example.

FIG. 9 shows the CO concentration of off-gas in the cleaning process of Comparative Example and Inventive Example 2 (a process of refining CO 2 by reusing the desorption gas) using an infrared continuous gas analyzer. Results are shown. CO is an impurity component during CO 2 recovery. According to FIG. 9, it can be seen that Invention Example 2 has higher removal efficiency of CO, which is an impurity, than the Comparative Example. In the comparative example, the cleaning off-gas through which the lower adsorbent packed bed (which corresponds to the lower part of the adsorbent packed bed in the case of a single adsorbent packed bed as provided in a conventional adsorption tower) is continuously supplied to the upper stage In the upper adsorbent packed bed (which corresponds to the upper part of the adsorbent packed bed in the case of a single adsorbent packed bed provided in a conventional adsorption tower). It reattaches and this reduces the CO removal efficiency.

A adsorption tower B gas flow path 1 a gas inlet 2 gas outlet 3,3 a, 3 b, 3 A , 3 B, 3 C, 3 D, 3 E, 3 F, 3 G adsorbent filling layer 4,4 A, 4 B, 4 C, 4 D, 4 E space 5,5 A, 5 B, 5 C , 5 D, 5 E gas entrance 6,6 a, 6 b, 6 c , 6 d, 6 A, 6 B, 6 C, 6 D , 6 E, 6 F, 6 G, 6 H, 6 I, 6 J, 6 K, 6 L, 6 M, 6 N off valve 7,8,9,10,10 A , 10 B , 10 C , 10 D , 10 E Gas piping 11, 12, 13, 14, 15, 16, 17, 18 Connection 70, 80, 90, 91, 92, 93, 94, 95, 96, 97 , 98 Piping part

Claims (9)

  1. An adsorption process in which a raw material gas is introduced into an adsorption tower and a specific gas component in the raw material gas is adsorbed, and a part of the desorption gas of another adsorption tower in which the desorption process is performed is completed. A cleaning process for introducing unnecessary gas components other than the specific gas components adsorbed on the adsorption tower and discharging them, and a specific gas adsorbed on the adsorption tower after the cleaning process is completed In a gas separation method for separating and recovering carbon dioxide gas , which is a specific gas component , from a steelworks byproduct gas, which is a raw material gas , by a pressure swing adsorption method having a component desorbed and recovered ,
    A gas separation facility for separating and recovering a specific gas component from a source gas by a pressure swing adsorption method, wherein a plurality of gas components are provided between a gas inlet part (1) at the lower end of the tower and a gas outlet part (2) at the upper end of the tower. An adsorbing tower provided with a gas inlet / outlet (5) for introducing or discharging gas from the space (4) while providing the adsorbent packed bed (3) in series with a space (4) not filled with the adsorbent. (A), a gas flow path (B) communicating with the gas inlet part (1), the gas outlet part (2), and the gas inlet / outlet (5) of the adsorption tower (A), and the gas flow path (B) A gas separation facility that allows one or more adsorbent packed beds (3) to bypass the gas in the adsorption tower (A) by switching the flow path using a plurality of open / close valves (6). Use
    The raw material gas in the adsorption step and / or the cleaning gas in the washing step is circulated in the adsorption tower (A) by bypassing one or more adsorbent packed beds (3) in at least part of the time zone in the step. A gas separation method using a pressure swing adsorption method.
  2.   The gas flow path (B) of the gas separation facility has a gas pipe (7) connected to the gas inlet part (1), a gas pipe (8) connected to the gas outlet part (2), and one end of the gas pipe. The gas pipe (9) connected (11) in the middle of (7) and the other end connected (12) in the middle of the gas pipe (8), one end connected to the gas inlet / outlet (5), and the other end The gas separation method according to claim 1, wherein the gas pipe (10) is connected (13) in the middle of the gas pipe (9).
  3.   During one process of flowing the raw material gas in the adsorption process and / or the cleaning gas in the cleaning process into the adsorption tower (A), one or more adsorbent packed beds (3) are bypassed only in a part of the time zone. 3. The gas separation method by pressure swing adsorption method according to claim 1 or 2, wherein the raw material gas in the adsorption step and / or the cleaning gas in the cleaning step is circulated in the adsorption tower (A).
  4.   The adsorbent packed bed (3) that bypasses the raw material gas in the adsorption step and / or the cleaning gas in the washing step during one step of flowing the raw material gas in the adsorption step and / or the washing gas in the washing step into the adsorption tower (A). The gas separation method by the pressure swing adsorption method according to any one of claims 1 to 3.
  5.   The raw material gas in the adsorption step and / or the cleaning gas in the cleaning step is distributed to all the adsorbent packed beds (3) in the adsorption tower (A) by the end of the step. 5. A gas separation method by the pressure swing adsorption method according to 4.
  6.   6. The pressure swing adsorption method according to claim 3, wherein the raw material gas in the adsorption step is circulated in the adsorption tower (A) by bypassing the lower adsorbent packed bed (3). Gas separation method.
  7.   The pressure swing adsorption method according to any one of claims 3 to 6, wherein the cleaning gas in the cleaning step is circulated in the adsorption tower (A) by bypassing the adsorbent packed bed (3) on the upper stage side. Gas separation method.
  8.   In one process of flowing the raw material gas in the adsorption process and / or the cleaning gas in the cleaning process into the adsorption tower (A), the off-gas composition is analyzed, and the gas path is switched based on the analysis result. The gas separation method by the pressure swing adsorption method in any one of Claims 3-7.
  9.   The cleaning gas in the cleaning process is circulated in the adsorption tower (A) by bypassing one or more adsorbent packed beds (3) in at least a part of the time zone in the process, or in the adsorption process The raw material gas is circulated in the adsorption tower (A) by bypassing one or more adsorbent packed beds (3) in at least a part of the time zone in the process, and the cleaning gas in the cleaning process is 9. At least part of the time zone in the process, one or more adsorbent packed beds (3) are bypassed and circulated in the adsorption tower (A). Gas separation method by pressure swing adsorption method.
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