CN111282397A - Pressure swing adsorption gas high-recovery-rate separation system and separation method thereof - Google Patents

Abstract

The invention discloses a separation system with high recovery rate of pressure swing adsorption gas and a separation method thereof, which solve the technical problem of low product gas recovery rate caused by small quantity of adsorption towers in the traditional medium and small-scale pressure swing adsorption system in the prior art. The system comprises a plurality of adsorption towers, N (N is more than or equal to 1) intermediate tanks, a plurality of program control valves and corresponding connecting pipelines, wherein in the circulation process, a certain pressure equalizing step is divided into N pressure equalizing steps, the pressure equalizing steps are sequentially performed on the adsorption towers with pressure equalizing and N intermediate tanks (from the 1 st to the Nth), the corresponding pressure equalizing step is divided into N pressure equalizing steps, and the adsorption towers with pressure equalizing steps are sequentially and reversely performed on the pressure equalizing and N intermediate tanks (from the Nth to the 1 st). The pressure equalizing method and the pressure equalizing device have the advantages that one pressure equalizing step is divided into N pressure equalizing steps, so that the pressure equalizing times of the pressure swing adsorption system are increased, the recovery rate of the device is improved, and the application range is expanded.

Description

Pressure swing adsorption gas high-recovery-rate separation system and separation method thereof

Technical Field

The invention belongs to the technical field of pressure swing adsorption gas separation, and particularly relates to a pressure swing adsorption gas high-recovery separation system and a separation method thereof.

Background

The pressure swing adsorption gas separation technology can separate hydrogen, helium, nitrogen, oxygen, methane, carbon monoxide and carbon dioxide gas from the mixed gas, and is widely applied to the fields of oil refining, chemical engineering, energy, metallurgy, environmental protection and the like.

The pressure swing adsorption hydrogen purification technology is the application technology which has the widest application, the largest scale and the most mature technology, can prepare hydrogen with the purity of 99 to 99.999 percent from various hydrogen-containing gas sources (such as reformed gas, low-pressure gas, shift gas, coke oven gas, methanol purge gas, synthetic ammonia purge gas and the like), and meets the requirements of various hydrogen-using scenes.

The pressure swing adsorption hydrogen purification technology generally adopts 4-16 tower process cycles, in the pressure swing adsorption cycle engineering, each adsorption tower sequentially completes an adsorption step, a pressure equalizing and reducing step, a forward discharging step, a reverse discharging step, a flushing step, a pressure equalizing and boosting step and a final boosting step, the flushing step is replaced by an evacuation step or an evacuation flushing step for the evacuation process, each adsorption tower is in different stages of the cycle in the cycle process, and the adsorption towers are mutually coupled to jointly complete a gas separation process.

The main performance indexes of the pressure swing adsorption device comprise the purity of product gas, the recovery rate of the product gas, the investment of the device and the like, the adsorption pressure of the common pressure swing adsorption hydrogen extraction is 0.6-6.0 MPag, the pressure equalizing frequency is 1-10 times, enough pressure equalizing frequency is needed to obtain higher hydrogen recovery rate, and 4-step pressure equalizing is generally adopted for the 2.5MPag shift gas.

In the conventional pressure swing adsorption method, a pressure equalizing and reducing step corresponds to a pressure equalizing and increasing step in a process cycle, and the pressure equalizing times are limited, for example, 2-step pressure equalizing is adopted in 4-tower process patents ZL00122638.X and US9695545B2, when one adsorption tower is in pressure equalizing and reducing, the adsorption tower in pressure equalizing and increasing corresponds to the adsorption tower, and 6 times of pressure equalizing, namely 10-1-6 processes, can be realized in a 10-tower process adopting the patent 200510020305. X. However, the more the number of adsorption columns, the more the programmed valves, the more complicated the system, and the higher the investment for medium and small-scale pressure swing adsorption equipment. The traditional pressure swing adsorption technology can not realize pressure equalization for many times on a small amount of adsorption tower process systems, thereby limiting the recovery rate of gas separation and purification.

Therefore, the invention designs a pressure swing adsorption gas high recovery rate separation system and a separation method thereof, and increases pressure equalizing for many times by adding the intermediate tank under the condition of unchanged number of adsorption towers, thereby realizing the pressure equalizing times which can be achieved by a plurality of adsorption towers with a small number of adsorption towers, and further improving the recovery rate of product gas to save investment. And when the number of times of pressure equalization is increased, the cycle time is kept unchanged, the efficiency is improved, a row of program control valves are shared by multiple times of pressure equalization, and the process is simpler.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: the separation system and the separation method thereof with high recovery rate of pressure swing adsorption gas are provided, and the technical problem of low product gas recovery rate caused by small number of adsorption towers in the traditional medium and small-scale pressure swing adsorption system in the prior art is solved.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a separation system with high recovery rate of pressure swing adsorption gas comprises a plurality of adsorption towers, a feed gas conveying pipeline and a desorption gas pipeline which are connected to the adsorption towers, a product gas outward conveying pipeline which is connected from the adsorption towers, and program control valves which are arranged on the feed gas conveying pipeline, the desorption gas pipeline and the product gas outward conveying pipeline; the adsorption tower is characterized by further comprising N middle tanks, pressure equalizing pipelines and flushing pipelines are connected to the adsorption tower, the pressure equalizing pipelines are respectively connected with the N middle tanks through pipelines, and the flushing pipelines are connected with at least one middle tank through pipelines.

Further, a final-rise pipeline is connected between the pressure-equalizing pipeline and the product gas output pipeline.

Furthermore, flow control valves are arranged on the desorption gas pipeline, the product gas outward conveying pipeline, the final lifting pipeline and the flushing pipeline; preferably, program control valves are arranged on pipelines which are respectively connected with the pressure equalizing pipelines of the N intermediate tanks.

Further, N is not less than 1; preferably, the N intermediate tanks are numbered sequentially from 1 st to nth, and the flushing line is connected with the nth intermediate tank through a pipe.

Further, the volume content of hydrogen in the raw gas conveyed by the raw gas conveying pipeline is not less than 40%, and the product gas conveyed by the product gas conveying pipeline is hydrogen.

Further, the pressure of the raw material gas conveyed by the raw material gas conveying pipeline is 1.2-6.0 MPag.

A separation method of a pressure swing adsorption gas high recovery rate separation system comprises the following steps:

step I, an adsorption step; step II, an unconventional uniform pressure drop step; step III, a conventional pressure equalizing and reducing step; step IV, reverse amplification; step V, a washing step; step VI, performing conventional pressure equalization rising; step VII, an unconventional pressure equalization rising step; and step VIII, and finally boosting.

Further, in the step II, the unconventional pressure equalizing and reducing step is that the adsorption tower and N intermediate tanks respectively perform pressure equalizing and reducing for N times when the adsorption tower is in pressure equalizing and reducing; preferably, when the adsorption tower performs pressure equalizing and reducing for N times, the pressure equalizing and reducing are performed from the 1 st intermediate tank to the Nth intermediate tank in sequence; further, in the step VII, the unconventional pressure equalization rising step is that the adsorption tower and N intermediate tanks are respectively subjected to pressure equalization rising for N times during pressure equalization rising; preferably, when the adsorption column is pressure-equalized N times, pressure equalization is performed in sequence from the nth intermediate tank to the 1 st intermediate tank.

Further, in the step V, the adsorption tower in the regeneration stage is washed and regenerated by gas in the Nth intermediate tank.

Furthermore, the gas in the Nth intermediate tank is only used for flushing and is not used for pressure equalization, the Nth pressure equalization and pressure drop step is changed into a sequential release step, and the sequential release step is carried out after the last pressure equalization and pressure drop step is adjusted.

Further, there are 4 adsorption towers, and the adsorption towers perform gas adsorption separation by adopting a 16-cycle step sequence, wherein the 16-cycle step sequence is specifically shown in the following table:

wherein, A: adsorption; (1-N) ED: (1-N) average pressure drop; (N +1) ED: (N +1) th average pressure drop; (N +2) ED: (N +2) th average pressure drop; d: releasing pressure in the reverse direction; p: flushing; (N +2) ER: the (N +2) th pressure is increased; (N +1) ER: the (N +1) th pressure is increased; (1-N) ER: the (1-N) pressure equalization; FR: finally boosting the pressure; IS: isolating;

preferably, step 1 is 60S, step 2 is 30S, step 3 is 20S, step 4 is 30S, step 5 is 60S, step 6 is 30S, step 7 is 20S, step 8 is 30S, step 9 is 60S, step 10 is 30S, step 11 is 20S, step 12 is 30S, step 13 is 60S, step 14 is 30S, step 15 is 20S, and step 16 is 30S.

Further, there are 5 adsorption towers, and the adsorption towers perform gas adsorption separation by adopting a 20-cycle sequence, wherein the 20-cycle sequence is specifically shown in the following table:

step (ii) of	1 tower	2 towers	3 Tower	4 towers	5 towers
						⑴	A	IS	P	D	(1～N)ED
⑵	A	(N+1)ER	P	P	(N+1)ED
						⑶	A	(1～N)ER	(N+2)R	P	(N+2)ED
⑷	A	FR	IS	P	D
						⑸	(1～N)ED	A	IS	P	D
⑹	(N+1)ED	A	(N+1)ER	P	P
						⑺	(N+2)ED	A	(1～N)ER	(N+2)ER	P
⑻	D	A	FR	IS	P
						⑼	D	(1～N)ED	A	IS	P
⑽	P	(N+1)ED	A	(N+1)ER	P
						⑾	P	(N+2)ED	A	(1～N)ER	(N+2)ER
⑿	P	D	A	FR	IS
						⒀	P	D	(1～N)ED	A	IS
⒁	P	P	(N+1)ED	A	(N+1)ER
						⒂	(N+2)ER	P	(N+2)ED	A	(1～N)ER
⒃	IS	P	D	A	FR
						⒄	IS	P	D	(1～N)ED	A
⒅	(N+1)ER	P	P	(N+1)ED	A
						⒆	(1～N)ER	(N+2)ER	P	(N+2)ED	A
⒇	FR	IS	P	D	A

Wherein, A: adsorption; (1-N) ED: (1-N) average pressure drop; (N +1) ED: (N +1) th average pressure drop; (N +2) ED: (N +2) th average pressure drop; d: releasing pressure in the reverse direction; p: flushing; (N +2) ER: the (N +2) th pressure is increased; (N +1) ER: the (N +1) th pressure is increased; (1-N) ER: the (1-N) pressure equalization; FR: finally boosting the pressure; IS: isolating;

preferably, the step ⑴ is 30S, the step ⑵ is 12S, the step ⑶ is 30S, the step ⑷ is 22S, the step ⑸ is 30S, the step ⑹ is 12S, the step ⑺ is 30S, the step ⑻ is 22S, the step ⑼ is 30S, the step ⑽ is 12S, the step ⑵ 0 is 30S, the step ⑵ 1 is 22S, the step ⑵ 2 is 30S, the step ⑵ 3 is 12S, the step ⑵ 4 is 30S, the step ⑵ 5 is 22S, the step ⑵ 6 is 30S, the step ⑵ 7 is 12S, the step ⑵ 8 is 30S, and the step ⑵ 9 is 22S.

Compared with the prior art, the invention has the following beneficial effects:

the invention increases pressure equalizing for many times by adding the intermediate tank under the condition of not changing the number of the adsorption towers, thereby realizing the pressure equalizing times which can be achieved by a plurality of adsorption towers with a small number of adsorption towers, improving the recovery rate of the product gas and saving the investment. And when the number of times of pressure equalization is increased, the cycle time is kept unchanged, the efficiency is improved, a row of program control valves are shared by multiple times of pressure equalization, and the process is simpler.

Drawings

Fig. 1 is a system structure block diagram of the 4-tower process and the separation system with the N-2.

Fig. 2 is a system structure block diagram of the 4-tower process and the separation system when N is 5.

Fig. 3 is a system structure block diagram of the 5-tower process and the separation system when N is 3.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the accompanying drawings. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation or be constructed and operated in a particular orientation, and thus, it should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; of course, mechanical connection and electrical connection are also possible; alternatively, they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

As shown in fig. 1-3, the separation system with high recovery rate for pressure swing adsorption gas provided by the present invention comprises a plurality of adsorption towers, a raw material gas delivery pipeline and a desorption gas pipeline connected to the adsorption towers, a product gas output pipeline connected from the adsorption towers, and program control valves installed on the raw material gas delivery pipeline, the desorption gas pipeline, and the product gas output pipeline; the adsorption tower is characterized by further comprising N middle tanks, pressure equalizing pipelines and flushing pipelines are connected to the adsorption tower, the pressure equalizing pipelines are respectively connected with the N middle tanks through pipelines, and the flushing pipelines are connected with at least one middle tank through pipelines.

A final-rise pipeline is connected between the pressure-equalizing pipeline and the product gas output pipeline. Flow control valves are arranged on the desorption gas pipeline, the product gas outward conveying pipeline, the final lifting pipeline and the flushing pipeline; preferably, program control valves are arranged on pipelines which are respectively connected with the pressure equalizing pipelines of the N intermediate tanks. N is not less than 1; preferably, the N intermediate tanks are numbered sequentially from 1 st to nth, and the flushing line is connected with the nth intermediate tank through a pipe. The volume content of hydrogen in the raw gas conveyed by the raw gas conveying pipeline is not less than 40%, and the product gas conveyed by the product gas conveying pipeline is hydrogen. The pressure of the raw material gas conveyed by the raw material gas conveying pipeline is 1.2-6.0 MPag.

A separation method of a pressure swing adsorption gas high recovery rate separation system comprises the following steps: step I, an adsorption step; step II, an unconventional uniform pressure drop step; step III, a conventional pressure equalizing and reducing step; step IV, reverse amplification; step V, a washing step; step VI, performing conventional pressure equalization rising; step VII, an unconventional pressure equalization rising step; and step VIII, and finally boosting.

In the step II, the unconventional pressure equalizing and reducing step is that the adsorption tower and N intermediate tanks respectively perform pressure equalizing and reducing for N times when the adsorption tower is in pressure equalizing and reducing; preferably, when the adsorption tower performs pressure equalizing and reducing for N times, the pressure equalizing and reducing are performed from the 1 st intermediate tank to the Nth intermediate tank in sequence; further, in the step VII, the unconventional pressure equalization rising step is that the adsorption tower and N intermediate tanks are respectively subjected to pressure equalization rising for N times during pressure equalization rising; preferably, when the adsorption column is pressure-equalized N times, pressure equalization is performed in sequence from the nth intermediate tank to the 1 st intermediate tank. In the step V, the gas in the Nth intermediate tank is used for flushing and regenerating the adsorption tower in the regeneration stage. Furthermore, the gas in the Nth intermediate tank is only used for flushing and is not used for pressure equalization, the Nth pressure equalization and pressure drop step is changed into a forward release step, and the forward release step is carried out after the last pressure equalization and pressure drop step is adjusted.

The number of the adsorption towers is 4, the gas adsorption separation is carried out by adopting a 16-cycle step sequence, and the 16-cycle step sequence is specifically shown in the following table:

step (ii) of	1 tower	2 towers	3 Tower	4 towers
					1	A	IS	P	(1～N)ED
2	A	(N+1)ER	P	(N+1)ED
					3	A	(1～N)ER	(N+2)ER	(N+2)ED
4	A	FR	IS	D
					5	(1～N)ED	A	IS	P
6	(N+1)ED	A	(N+1)ER	P
					7	(N+2)ED	A	(1～N)ER	(N+2)ER
8	D	A	FR	IS
					9	P	(1～N)ED	A	IS
10	P	(N+1)ED	A	(N+1)ER
					11	(N+2)ER	(N+2)ED	A	(1～N)ER
12	IS	D	A	FR
					13	IS	P	(1～N)ED	A
14	(N+1)ER	P	(N+1)ED	A
					15	(1～N)ER	(N+2)ER	(N+2)ED	A
16	FR	IS	D	A

Wherein, A: adsorption; (1-N) ED: (1-N) average pressure drop; (N +1) ED: (N +1) th average pressure drop; (N +2) ED: (N +2) th average pressure drop; d: releasing pressure in the reverse direction; p: flushing; (N +2) ER: the (N +2) th pressure is increased; (N +1) ER: the (N +1) th pressure is increased; (1-N) ER: the (1-N) pressure equalization; FR: finally boosting the pressure; IS: and (4) isolating. Preferably, step 1 is 60S, step 2 is 30S, step 3 is 20S, step 4 is 30S, step 5 is 60S, step 6 is 30S, step 7 is 20S, step 8 is 30S, step 9 is 60S, step 10 is 30S, step 11 is 20S, step 12 is 30S, step 13 is 60S, step 14 is 30S, step 15 is 20S, and step 16 is 30S.

The 4-tower pressure swing adsorption process of the invention has 16 steps in total, including 4 adsorption steps, 3 pressure equalizing and reducing steps, 1 reverse releasing step, 2 flushing steps, 3 pressure equalizing and increasing steps, 1 final boosting step and a cycle period of 560 seconds; wherein the 1 st pressure equalizing and reducing step is divided into N (N is more than or equal to 1) pressure equalizing and reducing steps, the adsorption tower is sequentially and respectively equalized with N intermediate tanks, and is firstly equalized with the 1 st pressure equalizing tank and is finally equalized with the Nth pressure equalizing tank; the 1 st pressure equalizing step is divided into N (N is more than or equal to 1) pressure equalizing steps, the adsorption tower is sequentially and respectively equalized with N intermediate tanks, and is firstly equalized with the Nth pressure equalizing tank and is finally equalized with the 1 st pressure equalizing tank; the regeneration purge gas comes from the nth intermediate tank. When the gas in the Nth intermediate tank only provides flushing gas and does not provide pressure equalization, the pressure equalization frequency of the process is N +1, the Nth pressure equalization and pressure drop step is changed into a sequential release step, and the sequential release step is carried out after the last pressure equalization and pressure drop step is adjusted.

The traditional 4-tower process only has 2 times of pressure equalization, while the 4-tower process of the invention circularly increases N times of pressure equalization, thereby not only improving the recovery rate of the 4-tower process, but also expanding the application pressure range of the 4-tower process from 1.6MPag to 6.0MPag, avoiding the increase of the pressure equalization times by increasing the number of adsorption towers in the traditional process, and further reducing the investment.

Fig. 1 is a system structure block diagram of a 4-1-4 cycle process, namely a 4-tower process, 4-step pressure equalization, and N is 2. The process consists of 4 adsorption towers, 2 intermediate tanks, 22 program control valves and 4 regulating valves, all the pressure equalizing process and the pressurizing process are completed by 4# valves, the process is simple, and the number of valves is small. In the 4-tower process, only 1 intermediate tank and 1 program control valve are added for pressure equalization every time. Fig. 2 is a system structure block diagram of a 4-1-6 cycle process, namely, a 4-tower process, 6-step pressure equalization, where N is 5, the gas in the 5 th intermediate tank is only used for a flushing step, the pressure equalization step of the adsorption tower and the 5 th intermediate tank is changed into a forward-placing step, that is, the unconventional pressure equalization frequency is 4, the conventional pressure equalization frequency is 2, the 6 th pressure equalization step is divided into two steps of pressure equalization and forward-placing, the pressure equalization is completed after the 6 th pressure equalization, and then the forward-placing step of the adsorption tower and the 5 th intermediate tank is performed.

The number of the adsorption towers is 5, and the adsorption towers adopt 20 circulation steps for gas adsorption separation, wherein the 20 circulation steps are shown in the following table:

wherein, A: adsorption; (1-N) ED: (1-N) average pressure drop; (N +1) ED: (N +1) th average pressure drop; (N +2) ED: (N +2) th average pressure drop; d: releasing pressure in the reverse direction; p: flushing; (N +2) ER: the (N +2) th pressure is increased; (N +1) ER: the (N +1) th pressure is increased; (1-N) ER: the (1-N) pressure equalization; FR: finally boosting the pressure; IS: isolating;

preferably, the step ⑴ is 30S, the step ⑵ is 12S, the step ⑶ is 30S, the step ⑷ is 22S, the step ⑸ is 30S, the step ⑹ is 12S, the step ⑺ is 30S, the step ⑻ is 22S, the step ⑼ is 30S, the step ⑽ is 12S, the step ⑵ 0 is 30S, the step ⑵ 1 is 22S, the step ⑵ 2 is 30S, the step ⑵ 3 is 12S, the step ⑵ 4 is 30S, the step ⑵ 5 is 22S, the step ⑵ 6 is 30S, the step ⑵ 7 is 12S, the step ⑵ 8 is 30S, and the step ⑵ 9 is 22S.

The 5-tower pressure swing adsorption process of the invention circulates, and has 20 steps, including 4 adsorption steps, 3 pressure equalizing and reducing steps, 2 reverse releasing steps, 6 flushing steps, 3 pressure equalizing and increasing steps, 1 final boosting step and a circulation period of 470 seconds; wherein the 1 st pressure equalizing and reducing step is decomposed into N (N is more than or equal to 1) pressure equalizing and reducing steps, the adsorption tower is sequentially and respectively equalized with N intermediate tanks, and is firstly equalized with the 1 st pressure equalizing tank and is finally equalized with the Nth pressure equalizing tank; the 1 st pressure equalizing step is divided into N (N is more than or equal to 1) pressure equalizing steps, the adsorption tower is sequentially and respectively equalized with N intermediate tanks, and is firstly equalized with the Nth pressure equalizing tank and is finally equalized with the 1 st pressure equalizing tank; the regeneration purge gas comes from the nth intermediate tank.

When the gas in the Nth intermediate tank only provides flushing gas and does not provide pressure equalization rise, the pressure equalization time of the process is (N + 1).

Fig. 3 is a system structure block diagram of a 5-1-5 cycle process, namely a 5-tower process, 5-step pressure equalization, and N is 3. The process consists of 5 adsorption towers, 3 intermediate tanks, 22 programmable valves and 4 regulating valves, all the pressure equalizing process and the pressurizing process are completed by 4# valves, the process is simple, and the number of valves is small. Compared with the 4-tower process, the 5-tower process adds 1 adsorption tower, has shorter cycle period and is suitable for larger-scale devices.

The invention increases pressure equalizing for many times by adding the intermediate tank under the condition of not changing the number of the adsorption towers, thereby realizing the pressure equalizing times which can be achieved by a plurality of adsorption towers with a small number of adsorption towers, improving the recovery rate of the product gas and saving the investment. And when the number of times of pressure equalization is increased, the cycle time is kept unchanged, the efficiency is improved, a row of program control valves are shared by multiple times of pressure equalization, and the process is simpler.

The invention discloses a pressure swing adsorption gas separation method and a system, wherein hydrogen is preferably selected as a product gas, the system comprises a plurality of adsorption towers and N (N is more than or equal to 1) intermediate tanks, and the pressure equalizing frequency of the pressure swing adsorption system is increased by decomposing one pressure equalizing step into N pressure equalizing steps, so that the recovery rate of the device is improved, and the application range is expanded.

The invention adds N (N is more than or equal to 1) middle tanks besides the adsorption tower needed by circulation, decomposes a certain pressure equalizing step into N pressure equalizing steps, the adsorption tower with pressure equalizing and pressure equalizing are carried out with N middle tanks (from the 1 st middle tank to the Nth middle tank), and decomposes the corresponding pressure equalizing and pressure rising step into N pressure equalizing and rising steps, and the adsorption tower with pressure equalizing and rising are carried out with N middle tanks (from the Nth middle tank to the 1 st middle tank) in reverse direction.

The invention uses the gas in the Nth intermediate tank to wash and regenerate the adsorption tower in the regeneration stage; the gas in the Nth intermediate tank can be only used for flushing and is not used for pressure equalization rise, and the Nth pressure equalization drop step is converted into a sequential step; the pressure equalizing and final boosting are completed by one row of valves. Only 1 intermediate tank and 1 valve need to be added for each pressure equalization. The number of adsorption columns is equal to or greater than 3, preferably 4 and 5; the pressure of the raw material gas is 1.2-6.0 MPag; the volume content of the product in the raw material gas is more than or equal to 40 percent; the product gas is preferably hydrogen.

Each adsorption tower of the invention sequentially goes through the following steps in one cycle: an adsorption step; an unconventional pressure drop equalizing step, namely equalizing the pressure of the adsorption tower and N intermediate tanks, reducing the pressure of the adsorption tower and increasing the pressure of the intermediate tanks; a conventional pressure equalizing and reducing step, namely equalizing the pressure between the two adsorption towers; a reverse amplification step; a washing step; a conventional pressure equalizing and raising step, namely equalizing pressure between the two adsorption towers; an unconventional pressure equalizing step, namely, equalizing the pressure of the adsorption tower and N intermediate tanks, increasing the pressure of the adsorption tower and reducing the pressure of the intermediate tanks; and finally, boosting the pressure.

Finally, it should be noted that: the above embodiments are only preferred embodiments of the present invention to illustrate the technical solutions of the present invention, but not to limit the technical solutions, and certainly not to limit the patent scope of the present invention; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention; that is, the technical problems to be solved by the present invention, which are not substantially changed or supplemented by the spirit and the concept of the main body of the present invention, are still consistent with the present invention and shall be included in the scope of the present invention; in addition, the technical scheme of the invention is directly or indirectly applied to other related technical fields, and the technical scheme is included in the patent protection scope of the invention.

Claims (10)

1. A separation system with high recovery rate of pressure swing adsorption gas comprises a plurality of adsorption towers, a feed gas conveying pipeline and a desorption gas pipeline which are connected to the adsorption towers, a product gas outward conveying pipeline which is connected from the adsorption towers, and program control valves which are arranged on the feed gas conveying pipeline, the desorption gas pipeline and the product gas outward conveying pipeline; the adsorption tower is characterized by further comprising N middle tanks, pressure equalizing pipelines and flushing pipelines are connected to the adsorption tower, the pressure equalizing pipelines are respectively connected with the N middle tanks through pipelines, and the flushing pipelines are connected with at least one middle tank through pipelines.

2. The pressure swing adsorption gas high recovery separation system of claim 1, wherein a final lift line is connected between the pressure equalization line and the product gas export line;

preferably, flow control valves are arranged on the desorption gas pipeline, the product gas outward conveying pipeline, the final lifting pipeline and the flushing pipeline;

more preferably, program control valves are arranged on pipelines of the N intermediate tanks respectively connected with the pressure equalizing pipeline.

3. The pressure swing adsorption gas high recovery separation system of claim 1, wherein N is not less than 1;

preferably, the N intermediate tanks are numbered sequentially from 1 st to nth, and the flushing line is connected with the nth intermediate tank through a pipe.

4. The pressure swing adsorption gas high recovery separation system of claim 1, wherein the volume content of hydrogen in the feed gas conveyed by the feed gas conveying line is not less than 40%, and the product gas conveyed by the product gas conveying line is hydrogen.

5. The pressure swing adsorption gas high recovery separation system of claim 1, wherein the pressure of the feed gas conveyed by the feed gas conveying pipeline is 1.2-6.0 MPag.

6. The separation method of the pressure swing adsorption gas high recovery separation system according to any one of claims 1 to 5, wherein the adsorption tower circularly separates and purifies the gas according to the following steps:

step I, an adsorption step;

step II, an unconventional uniform pressure drop step;

step III, a conventional pressure equalizing and reducing step;

step IV, reverse amplification;

step V, a washing step;

step VI, performing conventional pressure equalization rising;

step VII, an unconventional pressure equalization rising step;

and step VIII, and finally boosting.

7. The separation method according to claim 6, wherein in the step II, the unconventional pressure equalizing and reducing steps are respectively performed with N intermediate tanks for equalizing and reducing pressure N times when the adsorption tower is in equalizing and reducing pressure; preferably, when the adsorption tower performs pressure equalizing and reducing for N times, the pressure equalizing and reducing are performed from the 1 st intermediate tank to the Nth intermediate tank in sequence;

further, in the step VII, the unconventional pressure equalization rising step is that the adsorption tower and N intermediate tanks are respectively subjected to pressure equalization rising for N times during pressure equalization rising; preferably, when the adsorption column is pressure-equalized N times, pressure equalization is performed in sequence from the nth intermediate tank to the 1 st intermediate tank.

Further, in the step V, the adsorption tower in the regeneration stage is subjected to flushing regeneration by using the gas in the Nth intermediate tank.

8. The separation process of claim 6 wherein the gas in the nth tundish is used for flushing only and not for pressure equalization, and wherein the nth pressure equalization step is switched to a sequential release step which is adjusted to follow the last pressure equalization.

9. The separation process according to claim 6, wherein there are 4 adsorption columns for gas adsorption separation in a 16 cycle sequence, said 16 cycle sequence being specified in the following table:

wherein, A: adsorption; (1-N) ED: (1-N) average pressure drop; (N +1) ED: (N +1) th average pressure drop; (N +2) ED: (N +2) th average pressure drop; d: releasing pressure in the reverse direction; p: flushing; (N +2) ER: the (N +2) th pressure is increased; (N +1) ER: the (N +1) th pressure is increased; (1-N) ER: the (1-N) pressure equalization; FR: finally boosting the pressure; IS: isolating;

preferably, step 1 is 60S, step 2 is 30S, step 3 is 20S, step 4 is 30S, step 5 is 60S, step 6 is 30S, step 7 is 20S, step 8 is 30S, step 9 is 60S, step 10 is 30S, step 11 is 20S, step 12 is 30S, step 13 is 60S, step 14 is 30S, step 15 is 20S, and step 16 is 30S.

10. The separation process according to claim 6, wherein there are 5 adsorption columns for gas adsorption separation in 20 cycle steps, said 20 cycle steps being specified in the following table:

step (ii) of 1 tower 2 towers 3 Tower 4 towers 5 towers ⑴ A IS P D (1～N)ED ⑵ A (N+1)ER P P (N+1)ED ⑶ A (1～N)ER (N+2)R P (N+2)ED ⑷ A FR IS P D ⑸ (1～N)ED A IS P D ⑹ (N+1)ED A (N+1)ER P P ⑺ (N+2)ED A (1～N)ER (N+2)ER P ⑻ D A FR IS P ⑼ D (1～N)ED A IS P ⑽ P (N+1)ED A (N+1)ER P ⑾ P (N+2)ED A (1～N)ER (N+2)ER ⑿ P D A FR IS ⒀ P D (1～N)ED A IS ⒁ P P (N+1)ED A (N+1)ER ⒂ (N+2)ER P (N+2)ED A (1～N)ER ⒃ IS P D A FR ⒄ IS P D (1～N)ED A ⒅ (N+1)ER P P (N+1)ED A ⒆ (1～N)ER (N+2)ER P (N+2)ED A ⒇ FR IS P D A

Wherein, A: adsorption; (1-N) ED: (1-N) average pressure drop; (N +1) ED: (N +1) th average pressure drop; (N +2) ED: (N +2) th average pressure drop; d: releasing pressure in the reverse direction; p: flushing; (N +2) ER: the (N +2) th pressure is increased; (N +1) ER: the (N +1) th pressure is increased; (1-N) ER: the (1-N) pressure equalization; FR: finally boosting the pressure; IS: isolating;

preferably, the step ⑴ is 30S, the step ⑵ is 12S, the step ⑶ is 30S, the step ⑷ is 22S, the step ⑸ is 30S, the step ⑹ is 12S, the step ⑺ is 30S, the step ⑻ is 22S, the step ⑼ is 30S, the step ⑽ is 12S, the step ⑵ 0 is 30S, the step ⑵ 1 is 22S, the step ⑵ 2 is 30S, the step ⑵ 3 is 12S, the step ⑵ 4 is 30S, the step ⑵ 5 is 22S, the step ⑵ 6 is 30S, the step ⑵ 7 is 12S, the step ⑵ 8 is 30S, and the step ⑵ 9 is 22S.

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