Gas separation membrane operation method

Abstract

The present invention relates to a method for operating a gas separation membrane, the method including the steps of: (a) introducing an external gas into a separation membrane module through an inlet line; (b) separating the external gas into a permeable gas and an impermeable gas through the separation membrane module according to the permeability of the separation membrane, and delivering the permeable gas to a separation line and the impermeable gas to an outlet line; and (c) injecting at least a portion of the impermeable gas delivered to the outlet line into an inlet of the separation membrane module.

Description

[Technical field]

[0001] The present invention relates to a method of operating a gas separation membrane for scrubbing the gas separation membrane with gas separated by the gas separation membrane. [Background technology]

[0002] Gas separation membranes are used to separate various gases and have recently been increasingly used. However, conventional gas separation membrane technology has focused on membrane production technology, which is a manufacturing technology for separation membranes, and process design technology, and technological development for improving separation membrane contamination, which is a direct cause of reduced performance and lifespan of separation membranes, has been insufficient.

[0003] Conventionally, most methods have been to reduce membrane contamination by increasing the efficiency of exhaust gas pretreatment before supplying the exhaust gas to the separation membrane, and then to replace the contaminated separation membrane. However, this method can lead to problems such as reduced separation efficiency due to contamination or damage to the expensive separation membrane, or increased costs due to replacement.

[0004] To solve these problems, research is being conducted to improve separation efficiency by removing contamination of the separation membrane using external cleaning gases, water, chemicals, etc. However, the use of external cleaning gases and chemicals increases operating costs, pollutes the environment, and causes problems with secondary treatment.

[0005] Patent Document 1 discloses a method in which a gas used for cleaning the separation membrane is separately introduced from the outside. However, in this case, there is a problem that the cleaning cost increases. In addition, since a separate cleaning gas needs to be introduced from the outside, the gas separated by the gas membrane cannot be reused and must be discharged to the outside, and a separate structure is required to introduce the cleaning gas from the outside.

[0006] Patent Document 2 discloses a method of injecting water to wash the separation membrane and then injecting air to wash it back, but in this case, a separate structure is required to inject water, and there are problems in that wastewater is generated and the cost of treating it increases. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Republic of Korea Patent Publication No. 10-1911786 [Patent Document 2] Japanese Patent Publication No. 1995-136472 Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present invention is to provide a method for operating a gas separation membrane, which is capable of recycling gas that is separated by the gas separation membrane and discarded, to clean the gas separation membrane. [Means for solving the problem]

[0009] The present invention relates to a method for cleaning a gas separation membrane, the method including the steps of: (a) introducing an external gas into a separation membrane module through an inlet line; (b) separating the external gas into a permeable gas and a non-permeable gas through the separation membrane module according to its permeability through the separation membrane, and delivering the permeable gas to a separation line and the non-permeable gas to an outlet line; and (c) injecting at least a portion of the non-permeable gas delivered to the outlet line into an inlet of the separation membrane module.

[0010] According to an embodiment of the present invention, in step (c), the non-permeable gas may be stored in a cleaning tank connected to the outlet line, and the non-permeable gas stored in the cleaning tank may be injected into the inlet of the separation membrane module.

[0011] According to an embodiment of the present invention, in step (c), the non-permeable gas may be injected into the inlet of the separation membrane module through a cleaning line having one side connected to the cleaning tank and the other side connected to a side of the inlet line.

[0012] According to an embodiment of the present invention, in the step (c), the non-permeable gas may be circulated and injected multiple times without the inflow of the external gas. Effect of the Invention

[0013] According to the present invention, it is possible to prevent the accumulation of contamination sources inside the separation membrane, and to improve separation efficiency by releasing contamination from the separation membrane. It is also possible to ensure stability by utilizing gas flowing out from the separation membrane, and it is possible to extend the performance and lifespan of the gas separation membrane, thereby reducing the costs of operation and membrane replacement. [Brief description of the drawings]

[0014] [Figure 1] 1 is a side cross-sectional view showing a schematic diagram of a gas separation membrane cleaning device used for carrying out a gas separation membrane operating method according to the present invention; [Diagram 2] 1 is a flow chart illustrating a method for cleaning a gas separation membrane according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. In the description of the present invention, detailed descriptions of related known functions will be omitted if they are obvious to those skilled in the art and may unnecessarily obscure the gist of the present invention.

[0016] Fig. 1 is a side cross-sectional view showing a schematic diagram of a gas separation membrane cleaning apparatus used for carrying out a gas separation membrane operating method according to the present invention, and Fig. 2 is a flow chart showing a schematic diagram of a gas separation membrane cleaning method according to the present invention.

[0017] 1 and 2, a gas separation membrane cleaning apparatus used to perform the gas separation membrane operating method according to the present invention includes a separation membrane module 10, a cleaning tank 20, a cleaning line 30, and a control unit 40. Hereinafter, each component of the gas separation membrane cleaning apparatus will be described, along with each step of the gas separation membrane operating method performed therethrough. The gas separation membrane operating method includes a separation process and a cleaning process.

[0018] The steps of the separation process in the operation of the gas separation membrane are as follows:

[0019] An inlet line 1 is connected to one side of the separation membrane module 10, and an outlet line 2 is connected to the other side. A separation line 3 is connected to the side of the separation membrane module 10. The inlet line 1, the outlet line 2, and the separation line 3 are provided in the form of tubes. The separation membrane module 10 is provided with a plurality of separation membranes 11, which are in the form of extended tubes and provided in a bundle. The separation membranes 11 are, for example, a membrane for separating CO 2 N 2 CO separated from 2 It may be a collection separation membrane.

[0020] One side of the inlet line 1 is connected to a gas injector (not shown) for injecting an external gas at high pressure, and the other side is connected to the separation membrane module 10. The control unit 40 controls a pump (not shown) to inject the external gas from the gas injector into the separation membrane module 10 through the inlet line 1 (s10). The external gas corresponds to a gas to be separated through a gas separation membrane in the separation process, and is different from a gas used for cleaning the separation membrane in a cleaning process described below.

[0021] Next, the external gas is separated into a permeable gas and a non-permeable gas according to the permeability through the separation membrane 11 through the separation membrane module 10, and the permeable gas is transferred to the separation line 3 and the non-permeable gas is transferred to the outlet line 2 (s20). The permeable gas is a gas that has a high permeability through the separation membrane 11 of the separation membrane module 10 and passes through the separation membrane 11, and the non-permeable gas is a gas that has a relatively lower permeability through the separation membrane 11 than the permeable gas.

[0022] The separation membranes 11 of the separation membrane module 10 are arranged in the horizontal direction in the drawing. The separation membrane module 10 is configured so that the permeable gas that has permeated the separation membranes 11 passes in a direction perpendicular to the direction in which the separation membranes 11 are arranged, and the non-permeable gas that has not been able to permeate the separation membranes 11 passes in the same direction as the direction in which the separation membranes 11 are arranged.

[0023] Each separation membrane 11 of the separation membrane module 10 is connected at one side to an inlet line 1 and at the other side to an outlet line 2. The outer space of the separation membrane 11 is connected to a separation line 3.

[0024] Of the inflow gas injected into inflow line 1, the permeate gas permeates through separation membrane 11 in the radial direction and is permeated into the space outside separation membrane 11. The permeate gas is separated into separation line 3 communicating with the space outside separation membrane 11.

[0025] Of the external gases injected into the inlet line 1, the non-permeable gas flows into the inside of the separation membrane 11, moves in the length direction of the separation membrane 11, and is delivered to the outlet line 2 connected to the other side of the separation membrane 11.

[0026] The main causes of contamination and damage of the separation membrane 11 are dust, moisture, NOx, SOx, etc., and small amounts of contamination sources remaining after pretreatment of the inflow gas accumulate inside the separation membrane module 10. These substances react with moisture over time to cause membrane contamination and damage, adversely affecting the separation efficiency of the separation membrane module 10. In addition, since NOx and SOx react with moisture to form acids, the accumulation of moisture, NOx, and SOx inside the separation membrane must be minimized.

[0027] The steps of the cleaning process in the operation of the gas separation membrane are as follows:

[0028] After the separation process of introducing the external gas into the separation membrane module 10 and separating the gas, a cleaning process is performed in which at least a portion of the non-permeable gas delivered to the outlet line 2 is injected into the inlet 12 of the separation membrane module 10 (s30).

[0029] The cleaning tank 20 is connected to the outflow line 2, and at least a portion of the non-permeable gas is stored in the cleaning tank 20. The cleaning tank 20 is provided at the rear end of the gas separation membrane cleaning device, and stores a certain amount of non-permeable gas that is separated and discarded from the separation membrane module 10. After the inflow gas is separated, the remaining non-permeable gas is mainly N 2 , O 2 , CO 2 , CO, etc., and are composed of gases with lower permeability than the permeating gas.

[0030] The non-permeable gas that is not stored in the cleaning tank 20 is discharged to the outside through the discharge line 4. The cleaning tank 20 does not store any gas supplied from the outside other than the non-permeable gas. As will be described later, when contamination of the separation membrane module 10 occurs, the cleaning tank 20 utilizes the non-permeable gas stored in the cleaning tank 20 to clean the separation membrane module 10, which will be described in detail as follows.

[0031] The cleaning line 30 has one side connected to the inlet 12 of the separation membrane module 10 and the other side connected to the cleaning tank 20. The cleaning line 30 is provided in the form of a pipe. The impermeable gas stored in the cleaning tank 20 is supplied from the cleaning tank 20 to the cleaning line 30 at a pressure higher than the production pressure. The cleaning line 30 forms a path through which the impermeable gas supplied from the cleaning tank 20 is injected into the inlet 12 of the separation membrane module 10 through a valve 31. The control unit 40 injects the impermeable gas supplied from the cleaning tank 20 to the cleaning line 30 into the inlet 12 of the separation membrane module 10 through the valve 31.

[0032] One side of the washing line 30 may be connected to the inlet 12 of the separation membrane module 10 while communicating with the inlet line 1, so that the washing line 30 can be connected to the internal space of the separation membrane module 10 through the existing inlet line 1 without a need to separately connect the washing line 30 to the separation membrane module 10. However, the washing line 30 may also be connected to the inlet 12 of the separation membrane module 10 separately from the inlet line 1.

[0033] Meanwhile, in the cleaning process according to the present invention, the impermeable gas that has already been used in the above-mentioned separation process and stored in the cleaning tank 20 is circulated and injected multiple times into the inlet 12 of the separation membrane module 10 without the inflow of an external gas to be injected into the separation membrane module 10. The control unit 40 can control the valve 31, and the control unit 40 can control the impermeable gas to be circulated and injected into the inlet 12 of the separation membrane 11 at a predetermined period. Through this, the impermeable gas generated during the production process can be continuously supplied to the inlet 12 of the separation membrane 11, so that contamination sources within the separation membrane module 10 do not accumulate.

[0034] The non-permeable gas is injected into each separation membrane 11 of the separation membrane module 10 through the inlet 12 of the separation membrane module, thereby allowing contamination sources within the separation membrane module 10 to be desorbed and discharged.

[0035] As a result, the efficiency and lifespan of the separation membrane module 10 can be improved. In addition, since no separate chemicals are used, negative effects on the separation membrane 11 can be minimized, and since the impermeable gas is a gas generated during the production process, the impermeable gas can be smoothly circulated and supplied for cleaning the separation membrane module 10. For example, the separation membrane 11 according to the present invention can be used to 2 In the case of a collection and separation membrane, the non-permeable gas is mainly N 2 Since this is stable to the separation membrane 11, it is possible to improve the fouling of the separation membrane module 10 without a separate chemical stimulus.

[0036] According to the above-mentioned embodiment of the present invention, the present invention can minimize contamination and damage that occurs when gas is separated using a gas separation membrane, and can extend the life of the separation membrane. Unlike the conventional method that generally uses external gas or water, the present invention can reduce operating costs by recycling the gas that is discarded from the separated gas. That is, the present invention can recover and maintain the separation efficiency of the gas separation membrane that separates gas, and prevent contamination of the separation membrane module by utilizing the discarded gas.

[0037] It is to be noted again that the scope of protection of the present invention is not limited to the description and expression of the embodiments explicitly described above, and that the scope of protection of the present invention cannot be limited by obvious modifications or substitutions in the technical field to which the present invention belongs. [Explanation of symbols]

[0038] 1: Inlet line 2: Outflow line 3:Separation line 4: Discharge line 10: Separation membrane module 11: Separation membrane 12: Separation membrane module inlet 20: Cleaning tank 30: Washing line 31: Valve 40: Control unit

Claims

1. (a) introducing an external gas into a separation membrane module through an inlet line; (b) separating the external gas into a permeable gas and a non-permeable gas according to the permeability of the separation membrane through the separation membrane module, and delivering the permeable gas to a separation line and the non-permeable gas to an outlet line; (c) injecting the non-permeable gas stored in a cleaning tank into an inlet of the separation membrane module while preventing inflow of the external gas through the inlet line, thereby cleaning the separation membrane module.

2. The step (c) comprises:

2. The method of claim 1, wherein the non-permeable gas is stored in the cleaning tank connected to the outflow line, and the non-permeable gas stored in the cleaning tank is injected into the inlet of the separation membrane module.

3. The step (c) comprises:

3. The method of claim 2, wherein the non-permeable gas is injected into the inlet of the separation membrane module through a cleaning line having one side connected to the cleaning tank and the other side connected to a side of the inlet line.

4. The step (c) comprises:

2. The method for operating a gas separation membrane according to claim 1, wherein the non-permeable gas is circulated and injected a number of times.

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