A method for improving the yield of pressure swing adsorption (PSA) products

Abstract

A method for improving pressure swing adsorption (PSA) product yield includes gas generation, high-pressure adsorption regeneration, and high- and low-pressure linked regeneration. The invention incorporates a venturi aspirator. This program ensures that when two PSA adsorption tanks are regenerating, when the pressure in the desorption tank of one adsorption tank is high, high-pressure desorption gas flows through the venturi aspirator to generate suction, extracting residual gas from the other adsorption tank in the late desorption stage (with slightly higher pressure and residual fuel gas pipeline network). This ensures thorough regeneration of the adsorbent without consuming product gas, thereby improving the yield of the PSA device.

Description

Technical Field

[0001] The present invention relates to a gas purification process, in particular to a process for purifying gas by non-stop pressure swing adsorption (PSA). Background Art

[0002] The principle of pressure swing adsorption is to separate gas mixtures by exploiting the differences in the adsorption properties of adsorbents for different gas molecules, thereby improving the purity of the target gas. Typically, when the adsorbent has absorbed a certain level of impurities, it needs to be regenerated. This is done by desorbing the adsorbent, typically by reducing the pressure in the adsorption tank. During the desorption process, the discharged gas contains a higher level of impurities than the feed gas. Typically, the desorbed gas enters the fuel gas pipeline and is incinerated as fuel gas.

[0003] Fuel gas pipelines in enterprises all have a certain pressure, typically 0.3 MPa(g). This results in the PSA adsorption tank being limited to the minimum pressure of the pipeline during the desorption process, resulting in incomplete desorption of the adsorbent in the PSA adsorption tank. The conventional solution is to perform a long backflush with product gas from other PSA production lines connected in parallel to ensure that the adsorbent desorption meets the requirements, but this backflush process wastes a large amount of product gas. Summary of the Invention

[0004] The purpose of this invention is to provide a method for improving the yield of pressure swing adsorption (PSA) products. By adding a venturi vacuum pump, the adsorbent is completely regenerated without consuming additional energy or product gas, and the PSA yield is increased from 75% to over 85% with high reliability.

[0005] The technical solution for achieving the purpose of the invention is a method for improving the yield of pressure swing adsorption (PSA) products, comprising gas generation, high-pressure adsorption regeneration, and high- and low-pressure linked regeneration;

[0006] In the gas generation step, the raw gas enters the first pressure swing adsorption (PSA) adsorption tank through the raw gas inlet pipeline for normal adsorption, the product gas enters the product gas pipeline through the first program-controlled valve, the second pressure swing adsorption (PSA) adsorption tank and the third pressure swing adsorption (PSA) adsorption tank close the raw gas inlet channel and close the corresponding second program-controlled valve and the third program-controlled valve;

[0007] The high-pressure adsorption regeneration step includes opening a feed gas inlet passage for a second pressure swing adsorption (PSA) adsorption tank, closing a second programmable valve, and raising the internal pressure of the second pressure swing adsorption (PSA) adsorption tank to a certain high-pressure value P. Thereafter, the high-pressure valve is opened and the feed gas inlet passage is closed. Under the action of the high pressure, the gas containing contaminants in the second pressure swing adsorption (PSA) adsorption tank is pressed into a high-pressure desorption gas pipeline and then enters a venturi aspirator through the high-pressure desorption gas pipeline. After a suction force is generated in the venturi aspirator, exhaust is exhausted through the desorption gas exhaust pipe. When the exhaust volume of the venturi aspirator is reduced to a set value, the high-pressure valve is closed.

[0008] The high-low pressure linkage regeneration is as follows: the raw gas inlet channel of the third pressure swing adsorption (PSA) adsorption tank is opened, the third programmable valve is closed, and when the internal pressure of the third pressure swing adsorption (PSA) adsorption tank is increased to a certain high pressure value P, its high-pressure valve is opened and the raw gas inlet channel is closed. Under the action of high pressure, the gas containing pollutants in the third pressure swing adsorption (PSA) adsorption tank is pressed into the high-pressure desorption gas pipeline and enters the venturi vacuum pump through the high-pressure desorption gas pipeline. After the suction force is generated in the venturi vacuum pump, the gas is exhausted through the desorption gas exhaust pipe. The desorption gas exhaust pipe is exhausted and the low-pressure valve of the second pressure swing adsorption (PSA) adsorption tank is opened at the same time. Under the suction pressure of the venturi vacuum pump, the remaining pollutant-containing gas in the second pressure swing adsorption (PSA) adsorption tank is discharged, thereby realizing the regeneration of the adsorbent in the second pressure swing adsorption (PSA) adsorption tank.

[0009] Furthermore, the method further comprises cyclic adsorption regeneration;

[0010] In the cyclic adsorption regeneration step, after the adsorbent in the second pressure swing adsorption (PSA) adsorption tank is regenerated, when the adsorbent in the first pressure swing adsorption (PSA) adsorption tank needs to be regenerated, the first program-controlled valve corresponding to the first pressure swing adsorption (PSA) adsorption tank is closed, and at the same time, the feed gas inlet channel and the second program-controlled valve of the second pressure swing adsorption (PSA) adsorption tank are opened. When the second pressure swing adsorption (PSA) adsorption tank is working normally, when the pressure of the first pressure swing adsorption (PSA) adsorption tank is increased to a certain high pressure value P, its high pressure valve is opened and the feed gas inlet channel is closed. Under high pressure, the gas containing pollutants in the first pressure swing adsorption (PSA) adsorption tank is pressed into the high-pressure desorption gas pipeline and enters the venturi vacuum pump through the high-pressure desorption gas pipeline. After the suction force is generated in the venturi vacuum pump, the gas is exhausted through the desorption gas exhaust pipe. The exhaust of the desorption gas exhaust pipe opens the low-pressure valve of the third pressure swing adsorption (PSA) adsorption tank at the same time. Under the action of the suction pressure of the venturi vacuum pump, the remaining pollutant-containing gas in the third pressure swing adsorption (PSA) adsorption tank is discharged, thereby achieving the regeneration of the adsorbent in the third pressure swing adsorption (PSA) adsorption tank.

[0011] PSA adsorption tank desorption is a process of gradually decreasing pressure. This invention incorporates a venturi aspirator. This program ensures that when two PSA adsorption tanks are regenerated, when the pressure in one tank is high, the high-pressure desorption gas flows through the venturi aspirator to generate suction, extracting the residual gas from the other tank (which is in the later stages of desorption, with slightly higher pressure and residual fuel gas pipelines), ensuring complete adsorbent regeneration without consuming product gas, thereby improving the yield of the PSA unit.

[0012] The beneficial effects of the present invention are as follows:

[0013] 1. Eliminates the PSA adsorbent regeneration and backflushing process. No product gas is consumed.

[0014] 2. It can control the decomposition pressure of PSA and ensure the regeneration effect of the adsorbent.

[0015] 3. No extra energy consumption, no increase in operating costs, and no need to stop during the regeneration process. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0017] Figure 1 Schematic diagram of a system for improving pressure swing adsorption (PSA) product yield.

[0018] As shown in the figure, there are raw material gas inlet pipeline 1, first pressure swing adsorption (PSA) adsorption tank 2-1, second pressure swing adsorption (PSA) adsorption tank 2-2, second pressure swing adsorption (PSA) adsorption tank 2-3, product gas pipeline 3, first program-controlled valve 4-1, second program-controlled valve 4-2, third program-controlled valve 4-3, high-pressure desorption gas pipeline 5, venturi vacuum pump 6, low-pressure desorption gas pipeline 7, desorption gas exhaust pipe 8, and adsorbent 9. DETAILED DESCRIPTION

[0019] The embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0020] like Figure 1In the invention, a system for improving the yield of pressure swing adsorption (PSA) products comprises a first pressure swing adsorption (PSA) adsorption tank 2-1, a second pressure swing adsorption (PSA) adsorption tank 2-2, and a third pressure swing adsorption (PSA) adsorption tank 2-3 connected to a raw material inlet pipeline 1, wherein the lower ends of the first pressure swing adsorption (PSA) adsorption tank 2-1, the second pressure swing adsorption (PSA) adsorption tank 2-2, and the third pressure swing adsorption (PSA) adsorption tank 2-3 are respectively connected to the raw material inlet pipeline 1, and the upper end of the first pressure swing adsorption (PSA) adsorption tank 2-1 is connected to the product gas pipeline 3 through a first program-controlled valve 4-1, and the upper end of the second pressure swing adsorption (PSA) adsorption tank 2-3 is connected to the product gas pipeline 3 through a first program-controlled valve 4-1. -2 is connected to the product gas pipeline 3 through the second program-controlled valve 4-2, and the upper end of the third pressure swing adsorption (PSA) adsorption tank 2-3 is connected to the product gas pipeline 3 through the third program-controlled valve 4-3. The first pressure swing adsorption (PSA) adsorption tank 2-1, the second pressure swing adsorption (PSA) adsorption tank 2-2, and the third pressure swing adsorption (PSA) adsorption tank 2-3 are each connected to the high-pressure desorption gas pipeline 5 through a high-pressure valve. The first pressure swing adsorption (PSA) adsorption tank 2-1, the second pressure swing adsorption (PSA) adsorption tank 2-2, and the third pressure swing adsorption (PSA) adsorption tank 2-3 are each connected to the low-pressure desorption gas pipeline 7 through a low-pressure valve.

[0021] The high-pressure desorbed gas pipeline 5 is connected to the air inlet of the venturi vacuum pump 6. The high-pressure desorbed gas pipeline 5 is connected to the air outlet of the venturi vacuum pump 6. The first pressure swing adsorption (PSA) adsorption tank 2-1, the second pressure swing adsorption (PSA) adsorption tank 2-2, and the third pressure swing adsorption (PSA) adsorption tank 2-3 are all filled with adsorbent 9. The desorbed gas exhaust pipe 8 is connected to the outlet of the venturi vacuum pump 6.

[0022] A method for improving the yield of pressure swing adsorption (PSA) products includes gas generation, high-pressure adsorption regeneration, high- and low-pressure linkage regeneration, and cyclic adsorption regeneration;

[0023] In the gas generation step, the raw gas enters the first pressure swing adsorption (PSA) adsorption tank 2-1 through the raw gas inlet pipeline 1 for normal adsorption, and the produced product gas enters the product gas pipeline 3 through the first program-controlled valve 4-1. The second pressure swing adsorption (PSA) adsorption tank 2-2 and the third pressure swing adsorption (PSA) adsorption tank 2-3 close the raw gas inlet channel and close the corresponding second program-controlled valve 4-2 and third program-controlled valve 4-3.

[0024] The high-pressure adsorption regeneration step includes opening the feed gas inlet passage of the second pressure swing adsorption (PSA) adsorption tank 2-2, closing the second programmable valve 4-2, and raising the internal pressure of the second pressure swing adsorption (PSA) adsorption tank 2-2 to a certain high-pressure value P. Thereafter, the high-pressure valve is opened and the feed gas inlet passage is closed. Under the action of the high pressure, the gas containing contaminants from the second pressure swing adsorption (PSA) adsorption tank 2-2 is pressed into the high-pressure desorption gas pipeline 5 and then enters the venturi exhauster 6 through the high-pressure desorption gas pipeline 5. After a suction force is generated in the venturi exhauster 6, exhaust is exhausted through the desorption gas exhaust pipe 8. When the exhaust volume of the venturi exhauster 6 is reduced to a set value, the high-pressure valve is closed.

[0025] The high-low pressure linkage regeneration is as follows: the raw gas inlet channel of the third pressure swing adsorption (PSA) adsorption tank 2-3 is opened, the third programmable valve 4-3 is closed, and when the internal pressure of the third pressure swing adsorption (PSA) adsorption tank 2-3 is increased to a certain high pressure value P, its high-pressure valve is opened and the raw gas inlet channel is closed. Under the action of high pressure, the gas containing pollutants in the third pressure swing adsorption (PSA) adsorption tank 2-3 is pressed into the high-pressure desorption gas pipeline 5, and enters the venturi vacuum pump 6 through the high-pressure desorption gas pipeline 5. After the suction force is generated in the venturi vacuum pump 6, the gas is exhausted through the desorption gas exhaust pipe 8. The desorption gas exhaust pipe 8 is exhausted and the low-pressure valve of the second pressure swing adsorption (PSA) adsorption tank 2-2 is opened at the same time. Under the suction pressure of the venturi vacuum pump 6, the remaining pollutant-containing gas in the second pressure swing adsorption (PSA) adsorption tank 2-2 is discharged, thereby achieving the regeneration of the adsorbent in the second pressure swing adsorption (PSA) adsorption tank 2-2.

[0026] In the cyclic adsorption regeneration step, after the adsorbent in the second pressure swing adsorption (PSA) adsorption tank 2-2 is regenerated, when the adsorbent in the first pressure swing adsorption (PSA) adsorption tank 2-1 needs to be regenerated, the first program-controlled valve 4-1 corresponding to the first pressure swing adsorption (PSA) adsorption tank 2-1 is closed, and at the same time, the feed gas entry channel and the second program-controlled valve 4-2 of the second pressure swing adsorption (PSA) adsorption tank 2-2 are opened. When the second pressure swing adsorption (PSA) adsorption tank 2-2 is working normally, when the pressure of the first pressure swing adsorption (PSA) adsorption tank 2-1 is increased to a certain high pressure value P, its high pressure valve is opened, the feed gas entry channel is closed, and the second program-controlled valve 4-2 is opened. The gas containing pollutants in the first pressure swing adsorption (PSA) adsorption tank 2-1 is pressed into the high-pressure desorption gas pipeline 5 under the action of high pressure, and enters the venturi vacuum pump 6 through the high-pressure desorption gas pipeline 5. After the suction force is generated in the venturi vacuum pump 6, the gas is exhausted through the desorption gas exhaust pipe (8). The desorption gas exhaust pipe 8 exhausts and at the same time opens the low-pressure valve of the third pressure swing adsorption (PSA) adsorption tank 2-3. Under the action of the suction pressure of the venturi vacuum pump 6, the remaining gas containing pollutants in the third pressure swing adsorption (PSA) adsorption tank 2-3 is discharged, thereby realizing the regeneration of the adsorbent in the third pressure swing adsorption (PSA) adsorption tank 2-3.

[0027] Repeat the above steps to achieve continuous regeneration without stopping the machine.

[0028] Use common scenarios:

[0029] The first pressure swing adsorption (PSA) adsorption tank 2-1 is in normal adsorption production, and the second pressure swing adsorption (PSA) adsorption tank 2-2 needs to be regenerated, and the third pressure swing adsorption (PSA) adsorption tank 2-3 cooperates;

[0030] The first pressure swing adsorption (PSA) adsorption tank 2-1 is in normal production. The raw gas enters the first pressure swing adsorption (PSA) adsorption tank 2-1 through valve FC3 (inlet valve) to produce 98%\3.0MPa hydrogen. After adsorption, 99.9%\2.98MPa product hydrogen is produced.

[0031] The second pressure swing adsorption (PSA) adsorption tank 2-2 is regenerated for adsorbent, the second programmable valve 4-2 is closed, and the inlet valve corresponding to the second pressure swing adsorption (PSA) adsorption tank 2-2 is opened to increase the pressure of 3.0MPa raw hydrogen. Then, the high-pressure valve corresponding to the second pressure swing adsorption (PSA) adsorption tank 2-2 is opened. The 3.0MPa raw hydrogen enters the 0.3MMPa fuel gas pipeline through the Venturi vacuum pump and generates suction to remove part of the impurity-containing gas, and then the corresponding high-pressure valve is closed.

[0032] The third PSA tank 2-3 cooperates with the second programmable valve 4-3 to close. The corresponding inlet valve of the third PSA tank 2-3 is opened, increasing the pressure of the raw hydrogen to 3.0 MPa. The inlet valve is then closed, and the corresponding high-pressure valve of the third PSA tank 2-3 is opened. The 3.0 MPa raw hydrogen enters the 0.3 MMPa fuel gas network through the Venturi extractor, generating suction. This simultaneously opens the low-pressure valve of the second PSA tank 2-2, and the gas is pumped into the second PSA tank 2-2 by the Venturi extractor 6 to -0.07 MPa. The impurities adsorbed by the adsorbent in the second PSA tank 2-2 are then desorbed. Subsequently, the low-pressure valve of the second PSA tank 2-2 is closed, and the pressure is equalized to 3.0 MPa, entering a standby state.

[0033] In the actual production process, adjustments can be made according to the actual production situation.

[0034] The above process and method ensures continuous and stable production of the PSA unit. Compared to conventional product gas backflush processes, the desorption pressure in the adsorption tank can be reduced to -0.07 MPa, resulting in thorough adsorbent regeneration and ensuring the PSA unit can consistently and stably produce the desired product purity. Because there is no product gas backflush step, the PSA yield can be increased to over 93%, compared to the conventional 80%.

Claims

1. A method for improving the yield of pressure swing adsorption (PSA) products, characterized by: The method includes gas generation, high-pressure adsorption regeneration, and high- and low-pressure linkage regeneration; In the gas generation step, the raw gas enters the first pressure swing adsorption (PSA) adsorption tank (2-1) through the raw gas inlet pipeline (1) for normal adsorption, and the produced product gas enters the product gas pipeline (3) through the first program-controlled valve (4-1), and the second pressure swing adsorption (PSA) adsorption tank (2-2) and the third pressure swing adsorption (PSA) adsorption tank (2-3) close the raw gas inlet channel and close the corresponding second program-controlled valve (4-2) and the third program-controlled valve (4-3); The high-pressure adsorption regeneration step includes opening the raw gas inlet channel of the second pressure swing adsorption (PSA) adsorption tank (2-2) and closing the second programmable valve (4-2). When the internal pressure of the second pressure swing adsorption (PSA) adsorption tank (2-2) is increased to a certain high-pressure value P, opening its high-pressure valve and closing the raw gas inlet channel. Under the action of high pressure, the gas containing pollutants in the second pressure swing adsorption (PSA) adsorption tank (2-2) is pressed into the high-pressure decomposition gas pipeline (5) and enters the venturi vacuum pump (6) through the high-pressure decomposition gas pipeline (5). After the suction force is generated in the venturi vacuum pump (6), the gas is exhausted through the decomposition gas exhaust pipe (8). When the exhaust volume of the venturi vacuum pump (6) is reduced to a set value, the high-pressure valve is closed. The high-low pressure linkage regeneration is as follows: the raw gas inlet channel of the third pressure swing adsorption (PSA) adsorption tank (2-3) is opened, the third program-controlled valve (4-3) is closed, and when the internal pressure of the third pressure swing adsorption (PSA) adsorption tank (2-3) is increased to a certain high pressure value P, the high pressure valve is opened, and the raw gas inlet channel is closed. Under the action of high pressure, the gas containing pollutants in the third pressure swing adsorption (PSA) adsorption tank (2-3) is pressed into the high pressure analysis gas pipeline (5), and enters the venturi vacuum pump (6) through the high pressure analysis gas pipeline (5). After the suction force is generated in the venturi vacuum pump (6), the gas is exhausted through the analysis gas exhaust pipe (8). When the analysis gas exhaust pipe (8) is exhausted, the low pressure valve of the second pressure swing adsorption (PSA) adsorption tank (2-2) is opened. Under the action of the suction pressure of the venturi vacuum pump (6), the remaining pollutant-containing gas in the second pressure swing adsorption (PSA) adsorption tank (2-2) is discharged, thereby realizing the regeneration of the adsorbent in the second pressure swing adsorption (PSA) adsorption tank (2-2).

2. The method for improving the yield of pressure swing adsorption (PSA) products according to claim 1, characterized in that: The method also includes cyclic adsorption regeneration; In the cyclic adsorption regeneration step, after the adsorbent in the second pressure swing adsorption (PSA) adsorption tank (2-2) is regenerated, when the adsorbent in the first pressure swing adsorption (PSA) adsorption tank (2-1) needs to be regenerated, the first program-controlled valve (4-1) corresponding to the first pressure swing adsorption (PSA) adsorption tank (2-1) is closed, and at the same time, the raw gas inlet channel and the second program-controlled valve (4-2) of the second pressure swing adsorption (PSA) adsorption tank (2-2) are opened. When the second pressure swing adsorption (PSA) adsorption tank (2-2) is operating normally, when the pressure of the first pressure swing adsorption (PSA) adsorption tank (2-1) is increased to a certain high pressure value P, its high pressure valve is opened and the raw gas inlet channel is closed. Under the action of high pressure, the gas containing pollutants in the first pressure swing adsorption (PSA) adsorption tank (2-1) is pressed into the high-pressure analytical gas pipeline (5), and enters the venturi vacuum pump (6) through the high-pressure analytical gas pipeline (5). After the suction force is generated in the venturi vacuum pump (6), the gas is exhausted through the analytical gas exhaust pipe (8). The analytical gas exhaust pipe (8) is exhausted and the low-pressure valve of the third pressure swing adsorption (PSA) adsorption tank (2-3) is opened at the same time. Under the action of the suction pressure of the venturi vacuum pump (6), the remaining pollutant-containing gas in the third pressure swing adsorption (PSA) adsorption tank (2-3) is discharged, thereby realizing the regeneration of the adsorbent in the third pressure swing adsorption (PSA) adsorption tank (2-3).

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