TWI797749B - PSA gas backflush system and PSA gas backflush method - Google Patents

Abstract

A pressure swing adsorption gas backflush system, comprising: a pressure swing adsorption device; a polymer membrane filter device, which is fluidly connected to the pressure swing adsorption device; and a gas backflush pipeline, which is connected to the pressure swing adsorption device It is fluidly connected with the polymer membrane filter device, and is used for backflushing the separated nitrogen gas filtered by the polymer membrane filter device to the pressure swing adsorption device. A pressure swing adsorption gas backflush method, comprising: (a) filtering a gas through a pressure swing adsorption device; (b) filtering the gas treated in step (a) through a polymer membrane; and (c) filtering the gas treated in step (a) through a polymer membrane; (b) The separated nitrogen is flushed back to the pressure swing adsorption device. The pressure swing adsorption gas backflush system and the pressure swing adsorption gas backflush method of the present invention are suitable for purifying hydrogen.

Description

PSA gas backflush system and PSA gas backflush method

The invention relates to a pressure swing adsorption gas back flushing system, in particular to a pressure swing adsorption gas back flushing system for back flushing separated nitrogen after filtration to a pressure swing adsorption device. The invention relates to a pressure swing adsorption gas back flushing method, in particular to a pressure swing adsorption gas back flushing method for back flushing separated nitrogen after filtration to a pressure swing adsorption device.

The interior of the pressure swing adsorption device in the traditional pressure swing adsorption system will be filled with molecular sieves. The surface of the molecular sieve will have many molecular pores (pores). When the pressure rises, the gas molecules will be forced into the molecular pores. However, the molecules Smaller gases are not affected and can freely shuttle between molecular spaces. After the pressure drops, the gas with larger molecules will still stay in the molecular pores. At this time, there are three traditional ways to discharge them: 1. Use part of the gas purified by the pressure swing adsorption system for purging to sweep out the gas with larger molecules from the pores. 2. Vacuum the front end to suck out the gas with larger molecules remaining in the molecular pores. 3. Heating causes the gas to escape from the molecular pores by absorbing energy and vibrating. This method usually needs to be purged with clean gas.

In addition to energy-consuming heating, these three methods also need to consume part of the gas purified by the pressure swing adsorption system for purging, which will reduce the recovery efficiency. As shown in Figure 1, a kind of pressure swing adsorption system 10 is proposed in the prior art, comprising: a pressure swing adsorption device 11; a gas backwash pipeline 13, which is fluidly connected with the pressure swing adsorption device 11, and is used The gas part after being processed by the pressure swing adsorption device 11 is partially backwashed to the pressure swing adsorption device 11; The unit SLPM is standard liter per minute (standard liter per minute). Wherein, the polymer membrane filter device 12 is suitable for filtering the gas treated by the pressure swing adsorption device 12 to separate hydrogen and nitrogen in the gas, thereby recovering the hydrogen in the gas. However, this system uses clean gas after pressure swing adsorption for purging. Although this method can desorb the molecular sieve in the pressure swing adsorption device 11, it has the disadvantage of greatly reducing the hydrogen recovery efficiency.

As mentioned above, the traditional pressure swing adsorption system has the disadvantage of greatly reducing the hydrogen recovery efficiency. Therefore, it is necessary to provide a novel system and method to improve the hydrogen recovery efficiency.

In view of the above deficiencies in the prior art, the present invention provides a PSA gas backflush system and a PSA gas backflush method to improve hydrogen recovery efficiency.

One of the main technical means adopted to achieve the above purpose is to make the aforementioned pressure swing adsorption gas backflush system, including: a pressure swing adsorption unit; a polymer membrane filtration unit fluidly connected to the pressure swing adsorption unit; and A gas backflush pipeline, which is fluidly connected with the pressure swing adsorption device and the polymer membrane filter device, and is used to backflush the separated nitrogen gas filtered by the polymer membrane filter device to the pressure swing adsorption device.

Another main technical means adopted to achieve the above purpose is to make the aforementioned pressure swing adsorption gas backflush method, including: (a) filtering a gas through a pressure swing adsorption device to remove impurities from the gas; (b) filtering the gas treated in step (a) through a polymer membrane to separate hydrogen and nitrogen in the gas; and (c) flushing the nitrogen separated in step (b) back to the pressure swing adsorption device to purge the molecular sieve in the pressure swing adsorption device.

Compared with the traditional pressure swing adsorption system and method, the pressure swing adsorption gas backflush system and the pressure swing adsorption gas backflush method of the present invention have better hydrogen recovery efficiency.

The implementation of the present invention is described below through specific examples, and those skilled in the art can understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various modifications and changes can be made to the details in this specification based on different viewpoints and applications without departing from the spirit of the present invention.

The "fluid connection" mentioned herein includes direct "fluid connection" and indirect "fluid connection". For example, the "fluid connection" between A device and B device may include: the direct "fluid connection" between A device and B device; The indirect "fluid connection" between the A device and the B device through a C device.

Example 1

As shown in Figure 2, the pressure swing adsorption gas back flushing system 20 of embodiment 1 comprises: a pressure swing adsorption device 21; a polymer membrane filter device 22, which is fluidly connected with the pressure swing adsorption device 21; and a The gas backflush pipeline 23 is fluidly connected with the pressure swing adsorption device 21 and the polymer membrane filter device 22, and is used for backflushing the separated nitrogen gas filtered by the polymer membrane filter device 22 to the pressure swing Adsorption device 21. Wherein, the flow unit SLPM shown in Fig. 2 is a standard liter per minute (standard liter per minute), it should be understood that the flow shown in Fig. 2 is only an example, the present invention is not limited thereto, the technical field of the present invention Those with common knowledge can adjust the appropriate flow rate according to actual needs.

Wherein, the pressure swing adsorption device 21 is suitable for filtering a gas to adsorb a large amount of impurities in the gas.

Wherein, the polymer membrane filter device 22 is suitable for filtering the gas treated by the pressure swing adsorption device 21 to separate hydrogen and nitrogen in the gas, thereby recovering the hydrogen in the gas.

Wherein, the gas backflush pipeline 23 is suitable for purging the molecular sieve in the pressure swing adsorption device 21 with the nitrogen separated after being filtered by the polymer membrane filter device 22 .

Contrasting with Fig. 1, the pressure swing adsorption gas back flushing system 20 of embodiment 1 is to use the nitrogen gas separated after filtering by the polymer membrane filter device 22 to purge the molecular sieve in the pressure swing adsorption device 21, so that it is compared with that in Fig. The pressure swing adsorption system 10 shown in 1 has at least the following two excellent technical effects: 1. The flow rate of the purging gas can be increased from the original 80SLPM to 120SLPM, which can reduce the purging time and increase the frequency of adsorption. 2. Because the purging gas is changed from the original mixed gas to the nitrogen separated after being filtered by the polymer membrane filter device 22, the waste of hydrogen can be reduced, and the recovery efficiency of hydrogen can be increased from the original 42% to 70%.

Example 2

As shown in Figure 3, the pressure swing adsorption gas back flushing system 30 of embodiment 2 comprises: a pressure swing adsorption device 31; a polymer membrane filter device 32, which is fluidly connected with the pressure swing adsorption device 31; and a The gas backflush pipeline 33 is fluidly connected with the pressure swing adsorption device 31 and the polymer membrane filter device 32, and is used for backflushing the separated nitrogen gas filtered by the polymer membrane filter device 32 to the pressure swing Adsorption device 31.

The pressure swing adsorption device 31 , the polymer membrane filter device 32 and the gas backflush pipeline 33 in Embodiment 2 are the same as those in Embodiment 1, and will not be repeated here.

Compared with Embodiment 1, the pressure swing adsorption gas backflushing system 30 of Embodiment 2 further includes: a purification device 34, which is fluidly connected with the pressure swing adsorption device 31 and the polymer membrane filter device 32, and uses The moisture and impurities in the gas treated by the pressure swing adsorption device 31 are further removed. The installation of the purification device 34 can prevent the moisture and impurities in the gas treated by the pressure swing adsorption device 31 from poisoning the polymer membrane in the polymer membrane filter device 32 , so as to improve the stability of the pressure swing adsorption gas backflush system 30 . For example, the purification device 34 may include desiccant for adsorbing moisture and activated carbon for adsorbing impurities, but the present invention is not limited thereto.

Example 3

As shown in Figure 4, the pressure swing adsorption gas backflushing method of embodiment 3 includes: (a) filtering a gas through a pressure swing adsorption device to remove the impurity S101 in the gas; (b) passing through a polymer Membrane filtering the gas treated in step (a) to separate hydrogen and nitrogen S102 in the gas; and (c) flushing the nitrogen separated in step (b) back to the pressure swing adsorption device to purge the transformer Molecular sieve S103 in a pressure adsorption device.

Wherein, step (a) can filter a gas through the pressure swing adsorption device as described in embodiment 1 and embodiment 2.

Wherein, step (b) can filter the gas treated by step (a) through the polymer membrane filter device as described in embodiment 1 and embodiment 2.

Wherein, step (c) can backflush the nitrogen separated in step (b) to the pressure swing adsorption device through the gas backflush pipeline as described in embodiment 1 and embodiment 2.

In one embodiment, the pressure swing adsorption gas backflush method in Example 3 may further include: (b-0) before passing through a polymer membrane to filter the gas treated in step (a), further pass through the purification device to Purification of the gas treated in step (a) to further remove water vapor and impurities in the gas treated by the pressure swing adsorption device, thereby avoiding high poisoning of water vapor and impurities in the gas treated by the pressure swing adsorption device Molecular film to improve the stability of PSA gas backflush method.

The purpose of the PSA gas backflush system and PSA gas backflush method of the present invention is to remove impurities such as ammonia and water in the gas, and also to remove nitrogen and recover hydrogen. Since the pressure swing adsorption device needs to be purged and regenerated, only using the pressure swing adsorption device to remove three gases such as ammonia, water and nitrogen will result in a large loss of hydrogen. Therefore, the PSA gas backflush system and the PSA gas backflush method of the present invention first use the PSA device to remove ammonia and water and other gases, then use the polymer membrane to remove nitrogen, and then use the polymer membrane The nitrogen gas separated after filtration is used to purge the molecular sieve in the pressure swing adsorption device. The PSA gas backflush system and PSA gas backflush method of the present invention can increase the hydrogen recovery rate from 42% to 70% by the above technical means.

The above-mentioned embodiments are only illustrative of the present invention, not intended to limit the present invention. Anyone skilled in the art can make modifications and changes to the above-mentioned embodiments without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the rights of the present invention should be set forth in the scope of patent application described later.

10 Pressure swing adsorption system 11 Pressure swing adsorption device 12 Polymer membrane filtration device 13 Gas backflush pipeline 20 PSA gas backflush system 21 Pressure swing adsorption device 22 Polymer membrane filtration device 23 Gas backflush pipeline 30 PSA gas backflush system 31 Pressure swing adsorption device 32 Polymer membrane filtration device 33 Gas backflush pipeline 34 Purification device S101 step S102 step S103 step

[Figure 1] is a schematic diagram of a traditional PSA system. [Figure 2] is a schematic diagram of the pressure swing adsorption gas backflush system in Example 1. [Fig. 3] is a schematic diagram of the PSA gas backflush system in Example 2. [Fig. 4] is a flow chart of the hydrogen purification method in Example 3.

20 PSA gas backflush system 21 Pressure swing adsorption device 22 Polymer membrane filtration device 23 Gas backflush pipeline

Claims (2)

A pressure swing adsorption gas backwashing system, comprising: a pressure swing adsorption device, which is used to filter a gas to remove impurities in the gas; a polymer membrane filter device, which is fluid with the pressure swing adsorption device connected to separate the hydrogen and nitrogen in the gas; a gas backflush pipeline, which is fluidly connected with the pressure swing adsorption device and the polymer membrane filter device, and is used to filter the The separated nitrogen is flushed back to the pressure swing adsorption device; and a purification device is fluidly connected with the pressure swing adsorption device and the polymer membrane filtration device, and the purification device includes a desiccant and activated carbon for further removing Moisture and impurities in the gas treated by the pressure swing adsorption device. A pressure swing adsorption gas backflushing method, comprising: (a) filtering a gas through a pressure swing adsorption device to remove impurities in the gas; (b-0) filtering through a polymer membrane through step (a) Before the treated gas, the gas treated in step (a) is further purified through a purification device, and the purification device includes a desiccant and activated carbon to further remove moisture and moisture in the gas treated by the pressure swing adsorption device. (b) filter the gas treated in step (a) through a polymer membrane to separate hydrogen and nitrogen in the gas; and (c) backflush the nitrogen separated in step (b) to the variable pressure Adsorption device to purge the molecular sieve in the pressure swing adsorption device.

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