CN109276973B - Method for separating and purifying hydrogen from refining vent gas - Google Patents

Method for separating and purifying hydrogen from refining vent gas Download PDF

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CN109276973B
CN109276973B CN201811166789.2A CN201811166789A CN109276973B CN 109276973 B CN109276973 B CN 109276973B CN 201811166789 A CN201811166789 A CN 201811166789A CN 109276973 B CN109276973 B CN 109276973B
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CN109276973A (en
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张辉
麦惠林
刘主金
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Fujian Kaimeite Gas Co.,Ltd.
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D53/00Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/02Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
    • B01D53/04Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography with stationary adsorbents
    • B01D53/047Pressure swing adsorption
    • CCHEMISTRY; METALLURGY
    • C01INORGANIC CHEMISTRY
    • C01BNON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B3/00Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
    • C01B3/50Separation of hydrogen or hydrogen containing gases from gaseous mixtures, e.g. purification
    • C01B3/56Separation of hydrogen or hydrogen containing gases from gaseous mixtures, e.g. purification by contacting with solids; Regeneration of used solids
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D2253/00Adsorbents used in seperation treatment of gases and vapours
    • B01D2253/10Inorganic adsorbents
    • B01D2253/102Carbon
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D2253/00Adsorbents used in seperation treatment of gases and vapours
    • B01D2253/10Inorganic adsorbents
    • B01D2253/104Alumina
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D2253/00Adsorbents used in seperation treatment of gases and vapours
    • B01D2253/10Inorganic adsorbents
    • B01D2253/106Silica or silicates
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D2259/00Type of treatment
    • B01D2259/40Further details for adsorption processes and devices
    • B01D2259/40011Methods relating to the process cycle in pressure or temperature swing adsorption
    • B01D2259/40058Number of sequence steps, including sub-steps, per cycle
    • B01D2259/40062Four

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Abstract

The invention discloses a method for separating and purifying hydrogen from refining and chemical vent gas, which provides a four-section pressure swing adsorption gas separation device and adopts a four-section pressure swing adsorption process. The method can separate and purify the fuel gas and the hydrogen with high heat value from the refining vent gas, so that the refining vent gas is fully utilized, great economic benefits are obtained, the pollution of the refining vent gas to the environment is reduced, and great social benefits are obtained.

Description

Method for separating and purifying hydrogen from refining vent gas
Technical Field
The invention relates to waste gas treatment, in particular to a method for separating and purifying hydrogen from refining vent gas.
Background
At present, because domestic refineries do not pay enough attention to tail gas utilization, most of tail gas is combusted and discharged through a flare pipe network to generate CO2、H2O、SO2And a small amount of unburned H2S, the main pollutant discharged is SO2And unburned H2S, on one hand, resource waste is caused to a little extent, and on the other hand, environmental pollution is caused.
Disclosure of Invention
The invention provides a method for separating and purifying hydrogen from refinery vent gas, aiming at solving the technical problems of resource waste and environmental pollution caused by directly burning and discharging refinery vent gas in China at present.
The invention provides a method for separating and purifying hydrogen from refining vent gas, which provides a four-section pressure swing adsorption gas separation device, adopts a four-section pressure swing adsorption process, and sequentially performs the following operations:
the method comprises the steps that a raw material gas enters a first-stage pressure swing adsorption (PSA-1) gas separation device after being pressurized by a compressor to perform a first-stage pressure swing adsorption process, the raw material gas firstly enters a first-stage gas-water separator to remove liquid water, then enters a first-stage desulfurizing tower to reduce the content of hydrogen sulfide in the raw material gas to less than 20ppm, then enters a first-stage adsorption tower in an adsorption state from the bottom of the first-stage adsorption tower, and easily-adsorbed components in the raw material gas, namely part of methane, nitrogen, carbon monoxide and most of C under the sequential selective adsorption of alumina, silica gel and special carbon KYA0232 of an adsorption bed layer2、C2 +The components are adsorbed and desorbed to obtain fuel gas with high heat valueBesides, the unadsorbed substances contain a large amount of nitrogen, hydrogen and a small amount of methane, carbon monoxide, carbon dioxide and C2、 C2 +The first section of middle mixed gas of the components flows out from the top of the adsorption tower in an adsorption state and enters a second section of pressure swing adsorption (PSA-1) gas separation device;
the first section of intermediate mixed gas entering a second section of pressure swing adsorption (PSA-2) gas separation device enters a second section of adsorption tower in an adsorption state from the bottom of the second section of adsorption tower to carry out a second section of pressure swing adsorption process, and the easily-adsorbed components in the first section of intermediate mixed gas, namely nitrogen, methane, carbon monoxide, carbon dioxide and C, are sequentially selected and adsorbed by activated carbon and molecular sieves in an adsorption bed layer2、C2 +The components are absorbed, and the components are returned to the raw material gas for recycling after being resolved, and the unadsorbed second-stage intermediate mixed gas containing a large amount of nitrogen, hydrogen, a small amount of methane and carbon monoxide flows out of the top of the adsorption tower in an adsorption state and enters a third-stage pressure swing adsorption (PSA-3) gas separation device;
the second section of intermediate mixed gas entering a third section of pressure swing adsorption (PSA-3) gas separation device enters a third section of adsorption tower in an adsorption state from the bottom of the third section of adsorption tower, a third section of pressure swing adsorption process is carried out, under the sequential selective adsorption of activated carbon and molecular sieves on an adsorption bed layer, the easily-adsorbed components, namely nitrogen, methane and carbon monoxide, in the second section of intermediate mixed gas are adsorbed and then are sent out of a boundary area as vent gas after being analyzed, and the third section of intermediate mixed gas which is not adsorbed and contains a large amount of hydrogen and a small amount of nitrogen flows out of the top of the adsorption tower in the adsorption state and enters a fourth section of pressure swing adsorption (PSA-4) gas separation device;
and (3) allowing the third-section intermediate mixed gas entering a fourth-section pressure swing adsorption (PSA-4) gas separation device to enter a fourth-section adsorption tower in an adsorption state from the bottom of the fourth-section adsorption tower, performing a fourth-section pressure swing adsorption process, allowing nitrogen which is a component easy to adsorb in the third-section intermediate mixed gas to be adsorbed under the sequential selective adsorption of the adsorbent bed special carbon KYA0232 and the molecular sieve, resolving and returning the nitrogen to the raw material gas for recycling, wherein the unadsorbed hydrogen flows out of the top of the adsorption tower in the adsorption state and is delivered to a boundary zone as a product with qualified purity.
The method for separating and purifying hydrogen from the refining vent gas adopts the four-stage pressure swing adsorption gas separation process to separate and purify the fuel gas and the hydrogen with high calorific value from the refining vent gas, so that the refining vent gas is fully utilized, great economic benefits are obtained, the pollution of the refining vent gas to the environment is reduced, and great social benefits are obtained.
Wherein, the first pressure swing adsorption process is an adsorption process of 6 adsorption towers and 2 adsorption towers, and raw gas entering the bottom of the 2 adsorption towers in an adsorption state sequentially enters the adsorption towers according to a scheduled time sequence.
Wherein, the regeneration process sequence of the adsorption tower in the adsorption state at the first section is as follows:
forward discharge pressure (PP) → Isolation (IS) → uniform drop (E1D) → uniform drop (E2D) → inverse discharge one (D1) → inverse discharge two (D2) → evacuation (V) → evacuation rinsing (VP) → pressure equilibrium rising 2(E2R) → pressure equilibrium rising 1(E1R) → final boosting (FR).
Wherein, the second section of pressure swing adsorption process is an adsorption process of 6 adsorption towers and 2 adsorption towers, and raw gas entering the bottom of the 2 adsorption towers in an adsorption state sequentially enters the adsorption towers according to a scheduled time sequence.
Wherein, the regeneration process sequence of the second section of adsorption tower in the adsorption state is as follows:
isolation (IS) → homogeneous drop (E1D) → homogeneous drop (E2D) → inverse discharge one (D1) → inverse discharge two (D2) → evacuation (V) → evacuation rinsing (VP) → homogeneous drop (E2R) → homogeneous drop (E1R) → Final Rise (FR).
Wherein, the third pressure swing adsorption process is an adsorption process of 6 adsorption towers and 2 adsorption towers, and raw gas entering the bottom of the 2 adsorption towers in an adsorption state sequentially enters the adsorption towers according to a scheduled time sequence.
Wherein, the regeneration process sequence of the adsorption tower in the adsorption state in the third section is as follows:
isolation (IS) → homogeneous drop (E1D) → homogeneous drop (E2D) → inverse discharge (D) → evacuation (V) → vacuum flushing (VP) → homogeneous drop (E2R) → homogeneous drop (E1R) → Final Rise (FR).
Wherein, the fourth pressure swing adsorption process is an adsorption process of 5 adsorption towers and 2 adsorption towers, and raw gas entering the bottom of the 2 adsorption towers in an adsorption state sequentially enters the adsorption towers according to a scheduled time sequence.
Wherein, the regeneration process sequence of the fourth section of adsorption tower in the adsorption state is as follows:
isolation (IS) → homogeneous drop (E1D) → homogeneous drop (E2D) → inverse discharge one (D1) → inverse discharge two (D2) → evacuation (V) → evacuation rinsing (VP) → homogeneous drop (E2R) → homogeneous drop (E1R) → Final Rise (FR).
Drawings
FIG. 1 is a schematic process flow diagram of a four-stage pressure swing adsorption gas separation unit of the present invention for separating and purifying hydrogen from refinery vent gases, with lines A, B and C in the upper portion of FIG. 1 communicating with lines A, B and C, respectively, in the lower portion of FIG. 1.
Detailed Description
The features and advantages of the process for separating purified hydrogen from refinery flare of this invention will become more apparent from the following detailed description of specific embodiments of the process for separating purified hydrogen from refinery flare of this invention with reference to the accompanying drawings.
The raw material gas is the recycled refining vent gas:
composition of H2 CH4 C2 C3 C4 C5+ N2 CO CO2
Content (V%) 30.76 1.64 3.53 10.03 1.88 0.47 44.16 4.95 0.96 100
The raw material gas contains 12000ppm of hydrogen sulfide and is less than 20ppm after desulfurization.
Pressure: about 0.05 MPa.
Temperature: is less than or equal to 40 ℃.
Referring to FIG. 1, the process for separating and purifying hydrogen from refinery off vent gas of the present invention employs a four-stage Pressure Swing Adsorption (PSA) gas separation unit, namely: a first pressure swing adsorption (PSA-1) gas separation device 100, a second pressure swing adsorption (PSA-2) gas separation device 200, a third pressure swing adsorption (PSA-3) gas separation device 300 and a fourth pressure swing adsorption (PSA-4) gas separation device 400.
The invention relates to a method for separating and purifying hydrogen from refining vent gas, which is a four-stage Pressure Swing Adsorption (PSA) process:
the first stage pressure swing adsorption (PSA-1) process is used for adsorbing easily-adsorbed components in the raw material gas, namely part of methane, nitrogen, carbon monoxide and most of C2、C2 +The fuel gas with high heat value obtained after the components are resolved is sent out, and the unadsorbed fuel gas contains a large amount of nitrogen, hydrogen and a small amount of methane, carbon monoxide, carbon dioxide and C2、C2 +The first section of the intermediate mixed gas of the components enters a second section of the pressure swing adsorption (PSA-2) process.
The second pressure swing adsorption (PSA-2) process is used for adsorbing easily-adsorbed components of the first-stage intermediate mixed gas, namely nitrogen, methane, carbon monoxide, carbon dioxide and C2、C2 +Returning the desorbed components to the raw material gas for recycling, and introducing the unadsorbed second-stage intermediate mixed gas containing a large amount of nitrogen, hydrogen, a small amount of methane and carbon monoxide into a third-stage pressure swing adsorption (PSA-3) process.
The third pressure swing adsorption (PSA-3) process is used for adsorbing easily-adsorbed components, namely nitrogen, methane and carbon monoxide, in the second-stage intermediate mixed gas, the components are analyzed and then are taken as vent gas to be sent out of a boundary region, and the unadsorbed third-stage intermediate mixed gas containing a large amount of hydrogen and a small amount of nitrogen enters the fourth-stage pressure swing adsorption (PSA-4) process.
The fourth stage of pressure swing adsorption (PSA-4) process is used for adsorbing nitrogen which is easy to adsorb components in the middle mixed gas of the third stage, the nitrogen is returned to the raw material gas for recycling after being analyzed, and the unadsorbed hydrogen is a product with qualified purity and is sent out of the battery limits.
First stage pressure swing adsorption (PSA-1) gas separation plant 100 and first stage pressure swing adsorption (PSA-1) Process:
the first-stage pressure swing adsorption (PSA-1) gas separation device 100 comprises 1 first-stage gas-water separator 101, 2 desulfurization towers 100A/B, 6 first-stage adsorption towers 101A-F, 1 first-stage pressure equalizing tank 102, 2 first-stage vacuum pumps (A, B and C are in a group, D, E and F are in a group), 1 first-stage heat exchanger 104, 1 first-stage high-pressure buffer tank 103A, 1 first-stage low-pressure buffer tank 103B, 1 compressor 105, valves, pipelines and the like.
The first stage pressure swing adsorption (PSA-1) process is used for adsorbing easily adsorbed components in the raw material gas, namely part of methane, nitrogen and carbon monoxide and most of C2 and C2+, the fuel gas with high heat value obtained after desorption is sent to the outside, and the unadsorbed fuel gas contains a large amount of nitrogen, hydrogen and a small amount of methane, carbon monoxide, carbon dioxide and C2、C2 +The first section of the intermediate mixed gas of the components enters a second section of pressure swing adsorption (PSA-2) process.
The raw material gas with the pressure of about 0.05MPa and the temperature of less than or equal to 40 ℃ is pressurized to 0.65MPa by a compressor 105 and then enters a first-stage pressure swing adsorption (PSA-1) gas separation device 100, firstly enters a first-stage gas-water separator 101 to remove liquid water, then enters a first-stage desulfurizing tower 100A/B to reduce the content of hydrogen sulfide in the raw material gas to less than 20ppm, and then enters a first-stage adsorption tower in an adsorption state from the bottoms of first-stage adsorption towers 101A-F.
The first stage pressure swing adsorption (PSA-1) gas separation device 100 is an adsorption process with 6 adsorption towers and 2 adsorption towers, and each adsorption tower sequentially experiences the following steps:
1. adsorption (A) → 2. forward discharge pressure (PP) → 3. Isolation (IS) → 4. mean-fall (E1D) → 5. mean-fall (E2D) → 6. reverse discharge pressure (D1) → 7. reverse discharge pressure (D2) → 8. evacuation (V) → 9. evacuation rinsing (VP) → 10. pressure equalization rise 2(E2R) → 11. pressure equalization rise 1(E1R) → 12. final boost pressure (FR).
1. Adsorption (a): raw material gas enters an adsorption tower from the bottom of 2 adsorption towers entering an adsorption state of a first-stage pressure swing adsorption (PSA-1) gas separation device 100 according to a scheduled time sequence, each adsorption tower of the 2 adsorption towers entering the adsorption state undergoes an adsorption step, and easily-adsorbed components in the raw material gas, namely part of methane, nitrogen, carbon monoxide and most of C, are selectively adsorbed in turn by an adsorption bed layer of aluminum oxide, silica gel and special carbon KYA02322、C2 +The component is adsorbed, and the unadsorbed component contains a large amount of nitrogen, hydrogen and a small amount of methane, carbon monoxide, carbon dioxide and C2、C2 +The mixed gas in the first section flows out from the top of the adsorption tower in the adsorption state and enters the second section to be changedA pressure adsorption (PSA-2) gas separation unit 200. When the adsorption step is carried out until the adsorption front reaches the initial position of the reserved section of the outlet of the adsorption bed layer, the tower bottom feeding program control valve and the tower top outlet program control valve of the adsorption tower in the adsorption step are closed to stop adsorption, so that a section of unused adsorbent is reserved near the top outlet end of the adsorption tower, and the adsorption front is pushed forward for uniform pressure drop.
2. Cis (PP): after the step (A) of adsorption, the unadsorbed gas containing a large amount of nitrogen, hydrogen and a small amount of methane, carbon monoxide, carbon dioxide and C with higher pressure in the adsorption tower is absorbed along the adsorption direction2、C2 +The mixed gas in the first section of the component is returned to the raw material gas for recycling.
3. Isolation (IS): keeping for a certain time under the state that the feeding program control valve at the bottom of the adsorption tower and the outlet program control valve at the top of the adsorption tower in the step of adsorption (A) are closed to stop adsorption.
The adsorption bed layer begins to shift to the regeneration process:
4. homoleptic (E1D): after the Isolation (IS) step IS finished, the unadsorbed high-pressure gas containing a large amount of nitrogen, hydrogen and a small amount of methane, carbon monoxide, carbon dioxide and C in the adsorption tower IS absorbed along the adsorption direction2、C2 +The first intermediate mixed gas of the components is put into an adsorption tower which is subjected to the step of uniform pressure rise (E1R) after the analysis is finished, the outlet pressure equalizing program control valves of the two adsorption towers are firstly communicated, and the pressure of the two adsorption towers is basically equal when the uniform pressure drop (E1D) is finished, and the two adsorption towers are both at higher intermediate pressure. In the step of uniform descending (E1D), the adsorption front advances forward, and the components which are easy to be adsorbed in the adsorption tower, namely part of methane, nitrogen, carbon monoxide and most of C2、C2 +The components are as follows.
5. Mean average drop (E2D): after the step of uniform descending (E1D) is finished, closing the outlet pressure equalizing program control valve of the adsorption tower which finishes the step of uniform ascending (E1R), opening the inlet program control valve of the first section pressure equalizing tank 102, communicating the adsorption tower with the first section pressure equalizing tank 102, and enabling the adsorption tower to have higher intermediate pressure which is not adsorbed and contains a large amount of nitrogen, hydrogen, a small amount of methane and carbon monoxideCarbon dioxide, C2、C2 +The mixed gas in the first section of the components is put into a first section of pressure equalizing tank 102 with micro-positive pressure along the adsorption direction, and the pressure of the adsorption tower is basically equal to that of the first section of pressure equalizing tank 102 when the pressure equalizing in the step of secondary equalizing (E2D) is finished, and the pressure is in a lower middle pressure. In the step of two average falling (E2D), the adsorption front advances again, and further the easily adsorbed components in the adsorption tower, namely part of methane, nitrogen, carbon monoxide and most of C2、C2 +And (4) adsorbing the components.
6. Inverse one (D1): closing the pressure equalizing program control valve at the outlet end of the adsorption tower and opening the reverse release program control valve at the inlet end of the adsorption tower to ensure that the unadsorbed adsorption tower contains a large amount of nitrogen, hydrogen and a small amount of methane, carbon monoxide, carbon dioxide and C2、C2 +The first-stage intermediate mixed gas of the components is discharged to the first-stage high-pressure buffer tank 103B in the direction opposite to the direction of the feed, and the pressure in the adsorption tower is reduced from the lower intermediate pressure to about 20 KPa.
7. Inverse secondary (D2): completing the first step (D1), closing the inlet program control valve of the first section high-pressure buffer tank 103B, opening the inlet program control valve of the first section low-pressure buffer tank 103A, and making the unadsorbed substances in the adsorption tower contain a large amount of nitrogen, hydrogen and a small amount of methane, carbon monoxide, carbon dioxide and C2、C2 +The first-stage intermediate mixed gas of the components is discharged to a first-stage low-pressure buffer tank 103A in the direction opposite to the direction of the feed, and the pressure in the adsorption tower is reduced from 20KPa to the normal pressure.
8. Evacuation (V): completing the adsorption tower in the second reverse discharge step (D2), closing the reverse discharge program control valve, and evacuating the adsorption tower by switching the evacuation common program control valve and using 2 groups of vacuum pumps to reach-90 KPa, so that the components which are easy to be adsorbed, namely part of methane, nitrogen, carbon monoxide and most of C2、 C2 +The components are resolved from the adsorbent, enter a first section heat exchanger 104, and enter a first section low-pressure buffer tank 103A after being reduced to the normal temperature.
9. Evacuation rinse (VP): at the end of the evacuation (V), a small amount of gas is introduced from the pre-pressure boosting gas pipeline to enter from the top of the adsorption tower in the evacuation (V), and the adsorption tower is evacuated and flushed from top to bottom, so that the effect of thoroughly desorbing easily adsorbed components, namely part of methane, nitrogen, carbon monoxide and most of C2 and C2+ components from the adsorbent is enhanced.
10. Dimemor (E2R): finishing evacuating and flushing (VP) adsorption tower, opening the pressure equalizing program control valve at the outlet of the adsorption tower in the step of two-stage pressure equalization (E2R) and the inlet program control valve of the first stage pressure equalizing tank 102, communicating the adsorption tower with the first stage pressure equalizing tank 102, making the gas in the first stage pressure equalizing tank 102 enter the adsorption tower along the reverse adsorption direction, and when the pressure equalization of the step of two-stage pressure equalization (E2R) is finished, the pressure of the adsorption tower is basically equal to that of the first stage pressure equalizing tank 102 and the adsorption tower is all at a lower intermediate pressure.
11. One liter (E1R): and (3) completing the adsorption tower of the step of two uniform rises (E2R), closing an inlet program control valve of the first-stage pressure equalizing tank 102, opening an outlet pressure equalizing program control valve of the adsorption tower which is performing the step of one uniform pressure drop (E1D), communicating the two adsorption towers, and enabling the gas of the adsorption tower which is performing the step of one uniform pressure drop (E1D) to enter the adsorption tower which is performing the step of one uniform rise (E1R), wherein the pressures of the two adsorption towers are basically equal when the pressure equalizing of the step of one uniform rise (E1R) is finished, and the two adsorption towers are both at higher intermediate pressure.
12. Final liter (FR): the adsorption column, which completed a step of one-liter (E1R), was reversely pressurized to the adsorption pressure with the outlet gas of the adsorption column in the adsorption state. The adsorption front edge can be pushed to the feeding end of the bed layer by reverse pressurizing, and the concentration front edge is flattened as much as possible, which is beneficial to the next adsorption operation. The adsorption tower completes one cycle of operation after the end of the final lift (FR) step and is ready for the next cycle of adsorption operation.
The easily adsorbed components entering the first low-pressure buffer tank 103A, namely part of methane, nitrogen, carbon monoxide and most of C2、C2 +The components are sent out as fuel gas.
The whole operation process is carried out at the temperature of the raw material gas entering the tower.
First stage pressure swing adsorption (PSA-1) Process, time Unit Table (Table 1)
Figure BSA0000171567060000091
First stage pressure swing adsorption (PSA-1) Process, time Unit Table (Table 1)
Figure BSA0000171567060000101
First stage pressure swing adsorption (PSA-1) Process, time Unit Table (Table 1)
Figure BSA0000171567060000102
First stage pressure swing adsorption (PSA-4) Process, time Unit Table (Table 1)
Figure BSA0000171567060000103
First stage pressure swing adsorption (PSA-1) Process, time Unit Table (Table 1)
Figure BSA0000171567060000104
First stage pressure swing adsorption (PSA-1) Process, time Unit Table (Table 1)
Figure BSA0000171567060000111
First stage pressure swing adsorption (PSA-1) Process, time and pressure gauge (Table 2)
Figure BSA0000171567060000112
(II) second stage pressure swing adsorption (PSA-2) gas separation device 200 and second stage pressure swing adsorption (PSA-2) Process:
the second-stage pressure swing adsorption (PSA-2) gas separation device 200 comprises 6 second-stage adsorption towers 201A-201F, 1 second-stage pressure equalizing tank 201, 2 groups of second-stage vacuum pumps (A and B are one group, C is one group), 1 second-stage heat exchanger 204, 1 second-stage high-pressure buffer tank 202A, 1 second-stage low-pressure buffer tank 202B, valves, pipelines and other equipment.
The second pressure swing adsorption (PSA-2) process is used for adsorbing easily-adsorbed components of the first-stage intermediate mixed gas, namely nitrogen, methane, carbon monoxide, carbon dioxide and C2、C2 +Returning the desorbed second-stage intermediate mixed gas containing a large amount of nitrogen, hydrogen, a small amount of methane and carbon monoxide to the third-stage pressure swing adsorption (PSA-3) process.
The second stage pressure swing adsorption (PSA-2) gas separation device 200 is an adsorption process with 6 adsorption towers and 2 adsorption towers, and each adsorption tower successively experiences:
1. adsorption (A) → 2. Isolation (IS) → 3. homogeneous drop (E1D) → 4. homogeneous drop (E2D) → 5. inverse discharge one (D1) → 6. inverse discharge two (D2) → 7. evacuation (V) → 8. evacuation rinse (VP) → 9. homogeneous drop (E2R) → 10. homogeneous drop (E1R) → 11. final drop (FR).
1. Adsorption (a): unadsorbed gas from the first stage pressure swing adsorption (PSA-1) gas separation unit 100 contains a substantial amount of nitrogen, hydrogen, and a small amount of methane, carbon monoxide, carbon dioxide, C2、C2 +The mixed gas in the first section enters the adsorption tower from the bottom of the 2 adsorption towers in the adsorption state of the second pressure swing adsorption device 200 according to the scheduled time sequence, each adsorption tower in the 2 adsorption towers in the adsorption state undergoes the adsorption step, and the components which are easy to be adsorbed in the mixed gas in the first section, namely nitrogen, methane, carbon monoxide, carbon dioxide and C, are sequentially selected and adsorbed by the activated carbon and the molecular sieve in the adsorption bed layer2、C2 +The components are adsorbed, and the unadsorbed second-stage intermediate mixed gas containing a large amount of nitrogen, hydrogen, a small amount of methane and carbon monoxide flows out from the top of the adsorption tower in an adsorption state and enters a third-stage pressure swing adsorption (PSA-3) gas separation device 300. The adsorption step proceeds toWhen the adsorption front reaches the initial position of the reserved section of the outlet of the adsorption bed layer, the feeding program control valve at the bottom of the adsorption tower and the program control valve at the outlet of the tower top are closed to stop adsorption, so that a section of unused adsorbent is reserved near the outlet end of the tower top of the adsorption tower, and the adsorption front is pushed forward for uniform pressure drop.
2. Isolation (IS): keeping for a certain time under the state that the feeding program control valve at the bottom of the adsorption tower and the outlet program control valve at the top of the adsorption tower in the step of adsorption (A) are closed to stop adsorption.
The adsorption bed layer begins to shift to the regeneration process:
3. homoleptic (E1D): after the Isolation (IS) step IS finished, the second-stage intermediate mixed gas which IS not adsorbed in the adsorption tower and contains a large amount of nitrogen, hydrogen, a small amount of methane and carbon monoxide with higher pressure IS put into an adsorption tower which IS analyzed and IS in the step of uniform pressure rise (E1R), wherein the pressure equalizing program control valves at the outlets of the two adsorption towers are required to be communicated, and the pressures of the two adsorption towers are basically equal and are in the higher intermediate pressure when the pressure equalizing of the step of uniform pressure drop (E1D) IS finished. In the step of uniform descending (E1D), the adsorption front advances, and the components which are easy to be adsorbed in the adsorption tower, namely nitrogen, methane, carbon monoxide, carbon dioxide and C, are further adsorbed2、C2 +The components are as follows.
4. Mean average drop (E2D): after the step of uniform pressure reduction (E1D), closing an outlet pressure-equalizing program control valve for completing the step of uniform pressure reduction (E1R) of the adsorption tower, opening an inlet program control valve for the second-stage pressure-equalizing tank 201, communicating the adsorption tower with the second-stage pressure-equalizing tank 201, and enabling the second-stage intermediate mixed gas which is not adsorbed and contains a large amount of nitrogen, hydrogen, a small amount of methane and carbon monoxide and has higher intermediate pressure in the adsorption tower to enter the second-stage pressure-equalizing tank 201 with micro-positive pressure along the adsorption direction, wherein the pressures of the adsorption tower and the second-stage pressure-equalizing tank 201 are basically equal and are all at lower intermediate pressure when the step of uniform pressure reduction (E2D) is finished. The adsorption front is pushed forward again in the step of average falling (E2D), and the components which are easy to be adsorbed in the adsorption tower, namely nitrogen, methane, carbon monoxide, carbon dioxide and C are further absorbed2、C2 +And (4) adsorbing the components.
5. Inverse one (D1): and (3) closing the pressure equalizing program control valve at the outlet end of the adsorption tower and opening the reverse pressure releasing program control valve at the inlet end of the adsorption tower to discharge second-section intermediate mixed gas which is not adsorbed in the adsorption tower and contains a large amount of nitrogen, hydrogen, a small amount of methane and carbon monoxide to a second-section high-pressure buffer tank 202A in the direction opposite to the feeding direction, and reducing the pressure in the adsorption tower from the lower intermediate pressure to about 20 KPa.
6. Inverse secondary (D2): and (D1) finishing the adsorption tower in the first reverse release step, closing the inlet program control valve of the second section high-pressure buffer tank 202A, and opening the inlet program control valve of the second section low-pressure buffer tank 202B, so that the second section intermediate mixed gas which is not adsorbed and contains a large amount of nitrogen, hydrogen, a small amount of methane and carbon monoxide in the adsorption tower is discharged to the second section low-pressure buffer tank 202B in a direction opposite to the feeding direction, and the pressure in the adsorption tower is reduced to 10KPa from 20 KPa.
7. Evacuation (V): completing the adsorption tower in the second step of reverse discharge (D2), closing the inlet end reverse discharge program control valve, opening the evacuation program control valve, evacuating the adsorption tower by using 2 groups of vacuum pumps to reach-90 KPa, and allowing the components which are easy to be adsorbed, namely nitrogen, methane, carbon monoxide, carbon dioxide and C2、 C2 +The components are resolved from the adsorbent, enter the second section of heat exchanger 204, and enter the second section of low-pressure buffer tank 202B after being cooled to the normal temperature.
8. Evacuation rinse (VP): at the end of the evacuation (V), a small amount of gas is introduced from the pre-pressure gas line into the adsorption column from the top of the adsorption column in the evacuation (V), and the adsorption column is evacuated and flushed from the top to the bottom to reinforce the adsorbable components, i.e., nitrogen, methane, carbon monoxide, carbon dioxide, C2、C2 +The components are thoroughly resolved from the adsorbent.
9. Dimemor (E2R): finishing evacuating and flushing (VP) adsorption tower, opening the pressure equalizing program control valve at the outlet of the adsorption tower in the step of two-stage pressure equalization (E2R) and the inlet program control valve of the second-stage pressure equalization tank 201, communicating the adsorption tower with the second-stage pressure equalization tank 201, making the gas in the second-stage pressure equalization tank 201 enter the adsorption tower along the reverse adsorption direction, and when the pressure equalization of the step of two-stage pressure equalization (E2R) is finished, the pressure of the adsorption tower is basically equal to that of the second-stage pressure equalization tank 201, and the pressure is all at lower intermediate pressure.
10. One liter (E1R): and (3) completing the adsorption tower of the step of secondary pressure equalization (E2R), closing an inlet program control valve of the second section of pressure equalization tank 201, opening a pressure equalization program control valve of the adsorption tower which is performing the step of primary pressure equalization (E1D), communicating the two adsorption towers, and enabling the gas of the adsorption tower which is performing the step of primary pressure equalization (E1D) to enter the adsorption tower which is performing the step of primary pressure equalization (E1R), wherein the pressures of the two adsorption towers are basically equal when the pressure equalization of the step of primary pressure equalization (E1R) is finished, and the two adsorption towers are both at higher intermediate pressure.
11. Final liter (FR): the adsorption column, which completed a step of one-liter (E1R), was reversely pressurized to the adsorption pressure with the outlet gas of the adsorption column in the adsorption state. The adsorption front edge can be pushed to the feeding end of the bed layer by reverse pressurizing, and the concentration front edge is flattened as much as possible, which is beneficial to the next adsorption operation. The adsorption tower completes one cycle of operation after the end of the final lift (FR) step and is ready for the next cycle of adsorption operation.
The easily adsorbed components entering the second section of low-pressure buffer tank 202B are nitrogen, methane, carbon monoxide, carbon dioxide and C2、C2 +The components are returned to the raw material gas for recycling.
The whole operation process is carried out at the temperature of the raw material gas entering the tower.
Second stage pressure swing adsorption (PSA-2) Process, time Unit Table (Table 3)
Figure BSA0000171567060000151
Second stage pressure swing adsorption (PSA-2) Process, time Unit Table (Table 3)
Figure BSA0000171567060000152
Second stage pressure swing adsorption (PSA-2) Process, time Unit Table (Table 3)
Figure BSA0000171567060000153
Second stage pressure swing adsorption (PSA-2) Process, time Unit Table (Table 3)
Figure BSA0000171567060000154
Second stage pressure swing adsorption (PSA-2) Process, time Unit Table (Table 3)
Figure BSA0000171567060000161
Second stage pressure swing adsorption (PSA-2) Process, time Unit Table (Table 3)
Figure BSA0000171567060000162
Second stage pressure swing adsorption (PSA-2) Process, time and pressure gauge (Table 4)
Figure BSA0000171567060000163
(III) third stage pressure swing adsorption (PSA-3) gas separation device 300 and third stage pressure swing adsorption (PSA-3) Process:
the third-stage pressure swing adsorption (PSA-3) gas separation device 300 comprises 6 third-stage adsorption towers 301A-301F, 1 third-stage pressure equalizing tank 301, 2 groups of first-stage vacuum pumps (A, B and C are one group, D, E and F are one group), valves, pipelines and the like.
The third pressure swing adsorption (PSA-3) process is used for adsorbing easily-adsorbed components, namely nitrogen, methane and carbon monoxide, in the second-stage intermediate mixed gas, the components are analyzed and then sent out of a boundary area as vent gas, and the unadsorbed third-stage intermediate mixed gas containing a large amount of hydrogen and a small amount of nitrogen enters the fourth-stage pressure swing adsorption (PSA-4) process.
The third stage pressure swing adsorption (PSA-3) gas separation device 300 is an adsorption process with 6 adsorption towers and 2 adsorption towers, and each adsorption tower sequentially experiences:
1. adsorption (a) → 2. Isolation (IS) → 3. homogeneous drop (E1D) → 4. homogeneous drop (E2D) → 5. inverse discharge (D) → 6. evacuation (V) → 7. evacuation rinse (VP) → 8. homogeneous rise (E2R) → 9. homogeneous rise (E1R) → 10. Final Rise (FR).
1. Adsorption (a): the second-stage intermediate mixed gas containing a large amount of nitrogen, hydrogen and a small amount of methane and carbon monoxide, which is not adsorbed, from the second-stage pressure swing adsorption (PSA-2) gas separation device 200 enters the adsorption towers from the bottoms of the 2 adsorption towers entering the adsorption state of the third-stage pressure swing adsorption (PSA-3) gas separation device 300 according to a scheduled time sequence, each adsorption tower of the 2 adsorption towers entering the adsorption state undergoes an adsorption step, under the sequential selective adsorption of the activated carbon and the molecular sieve of the adsorption bed, the easily-adsorbed components, namely nitrogen, methane and carbon monoxide, in the second-stage intermediate mixed gas are adsorbed, and the unadsorbed third-stage intermediate mixed gas containing a large amount of hydrogen and a small amount of nitrogen flows out of the top of the adsorption tower in an adsorption state and enters a fourth-stage pressure swing adsorption (PSA-4) gas separation device 400. And (3) when the adsorption step is carried out until the adsorption front edge reaches the initial position of the reserved section of the outlet of the adsorption bed layer, closing the tower bottom feeding program control valve and the tower top outlet program control valve of the adsorption tower in the adsorption (A) step to stop adsorption, so that a section of unused adsorbent is reserved near the tower top outlet end of the adsorption tower for the forward propulsion of the adsorption front edge during uniform pressure drop.
2. Isolation (IS): keeping for a certain time under the state that the feeding program control valve at the bottom of the adsorption tower and the outlet program control valve at the top of the adsorption tower in the step of adsorption (A) are closed to stop adsorption.
The adsorption bed layer begins to shift to the regeneration process:
3. homoleptic (E1D): after the Isolation (IS) step IS finished, the hydrogen and nitrogen which are not adsorbed at higher pressure in the adsorption tower are put into an adsorption tower which IS analyzed and IS in a step of uniform pressure rise (E1R) at lower pressure along the adsorption direction, the outlet pressure equalizing program control valves of the two adsorption towers are communicated, and the pressure of the two adsorption towers IS basically equal and IS in higher intermediate pressure when the uniform pressure rise (E1D) step IS finished. In the step of uniformly dropping (E1D), the adsorption front advances, and the easily adsorbed components in the adsorption tower, namely nitrogen, methane and carbon monoxide, are further adsorbed.
4. Mean average drop (E2D): after the step of uniform reduction (E1D) is finished, closing an outlet pressure equalizing program control valve of the adsorption tower in the step of uniform reduction (E1R), opening an inlet program control valve of the third section pressure equalizing tank 301, communicating the adsorption tower with the third section pressure equalizing tank 301, putting hydrogen and nitrogen which are not adsorbed at higher intermediate pressure in the tower into the third section pressure equalizing tank 301 with slight positive pressure along the adsorption direction, and when the pressure equalizing in the step of second uniform reduction (E2D) is finished, the pressures of the adsorption tower and the third section pressure equalizing tank 301 are basically equal and are both at lower intermediate pressure. In the step of average descending (E2D), the adsorption front is pushed forward again, and the components which are easily adsorbed in the adsorption tower, namely nitrogen, methane and carbon monoxide, are adsorbed more thoroughly.
5. Reverse (D): and (3) closing the pressure-equalizing program control valve at the outlet end of the adsorption tower and opening the reverse-discharge program control valve at the inlet end of the adsorption tower to discharge the gas in the adsorption tower to the outside in the direction opposite to the feeding direction to be discharged.
6. Evacuation (V): and (D) closing the reverse-discharge program control valve at the inlet end of the adsorption tower, opening the pre-evacuation program control valve, evacuating the adsorption tower by using 2 groups of vacuum pumps to reach-90 KPa, resolving adsorbed components, namely nitrogen, methane and carbon monoxide, from the adsorbent, and discharging to the outside for evacuation.
7. Evacuation rinse (VP): and introducing a small amount of gas from a pre-pressure boosting gas pipeline from the top of the adsorption tower in the evacuation (V) step to the end of the evacuation (V) step, and evacuating and flushing the adsorption tower from top to bottom so as to enhance the effect of thoroughly desorbing the easily adsorbed components, namely nitrogen, methane and carbon monoxide, from the adsorbent.
8. Dimemor (E2R): after the step (V) of evacuation is completed, the adsorption tower is regenerated, but the adsorption tower at higher negative pressure must be pressurized to adsorption pressure for next adsorption operation, the pressure equalizing program control valve at the outlet of the adsorption tower and the inlet program control valve of the third section pressure equalizing tank 301 are opened, the adsorption tower is communicated with the third section pressure equalizing tank 301, so that gas in the third section pressure equalizing tank 301 enters the adsorption tower in the direction opposite to the adsorption direction, and when the pressure equalizing in the step (E2R) of second uniform rising is finished, the pressures of the adsorption tower and the third section pressure equalizing tank 301 are basically equal and are both at lower intermediate pressure.
9. One liter (E1R): and (3) completing the adsorption tower of the step of secondary pressure equalization (E2R), closing an inlet program control valve of a third section of pressure equalization tank 301, opening an outlet pressure equalization program control valve of the adsorption tower which is performing the step of primary pressure equalization (E1D), communicating the two adsorption towers, enabling the gas of the adsorption tower which is performing the step of primary pressure equalization (E1D) to enter the adsorption tower which is performing the step of primary pressure equalization (E1R), and enabling the pressures of the two adsorption towers to be basically equal when the pressure equalization of the step of primary pressure equalization (E1R) is finished and to be at a higher intermediate pressure.
10. Final liter (FR): the adsorption column, which completed a step of one-liter (E1R), was reversely pressurized to the adsorption pressure with the outlet gas of the adsorption column in the adsorption state. The adsorption front edge can be pushed to the feeding end of the bed layer by reverse pressurizing, and the concentration front edge is flattened as much as possible, which is beneficial to the next adsorption operation. The adsorption tower completes one cycle of operation after the end of the final lift (FR) step and is ready for the next cycle of adsorption operation.
The whole operation process is carried out at the temperature of the raw material gas entering the tower.
Third stage pressure swing adsorption (PSA-3) Process, time Unit Table (Table 5)
Figure BSA0000171567060000191
Third stage pressure swing adsorption (PSA-3) Process, time Unit Table (Table 5)
Figure BSA0000171567060000192
Third stage pressure swing adsorption (PSA-3) Process, time Unit Table (Table 5)
Figure BSA0000171567060000201
Third stage pressure swing adsorption (PSA-4) Process, time Unit Table (Table 5)
Figure BSA0000171567060000202
Third stage pressure swing adsorption (PSA-3) Process, time Unit Table (Table 5)
Figure BSA0000171567060000203
Third stage pressure swing adsorption (PSA-3) Process, time Unit Table (Table 5)
Figure BSA0000171567060000204
Third stage pressure swing adsorption (PSA-3) Process, time and pressure gauge (Table 6)
Figure BSA0000171567060000211
(IV) fourth stage pressure swing adsorption (PSA-4) gas separation unit 400 and fourth stage pressure swing adsorption (PSA-4) Process:
the fourth pressure swing adsorption (PSA-4) gas separation device 400 comprises 5 fourth adsorption towers 401A-401E, 1 fourth pressure equalizing tank 401, 1 fourth high-pressure buffer tank 402, 2 groups of first vacuum pumps (A and B are one group, C is one group), 1 fourth heat exchanger 404, valves, pipelines and other equipment.
And the fourth stage of pressure swing adsorption (PSA-4) process is used for adsorbing nitrogen which is easy to adsorb components in the middle mixed gas of the third stage, the nitrogen is returned to the raw material gas for recycling after being analyzed, and unadsorbed hydrogen is a product with qualified purity and is sent out of the battery limit.
The fourth pressure swing adsorption (PSA-4) gas separation device 400 is an adsorption process with 5 adsorption towers and 2 adsorption towers, and each adsorption tower successively experiences:
1. adsorption (A) → 2. Isolation (IS) → 3. homogeneous drop (E1D) → 4. homogeneous drop (E2D) → 5. inverse discharge one (D1) → 6. inverse discharge two (D2) → 7. evacuation (V) → 8. evacuation rinse (VP) → 9. homogeneous drop (E2R) → 10. homogeneous drop (E1R) → 11. final drop (FR).
1. Adsorption (a): the unadsorbed third section intermediate mixed gas containing a large amount of hydrogen and a small amount of nitrogen from the third section pressure swing adsorption (PSA-3) gas separation device 300 enters the adsorption towers from the bottoms of the 2 adsorption towers entering the adsorption state of the fourth section pressure swing adsorption (PSA-4) gas separation device 400 according to a scheduled time sequence, each adsorption tower of the 2 adsorption towers entering the adsorption state undergoes an adsorption step, nitrogen which is a component easy to be adsorbed in the third section intermediate mixed gas is adsorbed under the sequential selective adsorption of the adsorbent bed special carbon KYA0232 and a molecular sieve, and the unadsorbed hydrogen flows out from the top of the adsorption tower in the adsorption state and is sent out of a battery limit as a product with qualified purity. And (3) when the adsorption step is carried out until the adsorption front reaches the initial position of the reserved section of the outlet of the adsorption bed layer, the tower bottom feeding program control valve and the tower top outlet program control valve of the adsorption tower in the adsorption (A) step are closed to stop adsorption, so that a section of unused adsorbent is reserved near the top outlet end of the adsorption tower, and the adsorption front is pushed forward for use during uniform pressure drop.
2. Isolation (IS): keeping for a certain time under the state that the feeding program control valve at the bottom of the adsorption tower and the outlet program control valve at the top of the adsorption tower in the step of adsorption (A) are closed to stop adsorption.
The adsorption bed layer begins to shift to the regeneration process:
3. homoleptic (E1D): after the Isolation (IS) step IS finished, the hydrogen which IS not adsorbed at higher pressure in the adsorption tower IS put into the adsorption tower which IS in the step of uniform pressure rise (E1R) and has been analyzed and IS at lower pressure along the adsorption direction, the outlet pressure equalizing program control valves of the two adsorption towers are communicated, and the pressure of the two adsorption towers IS basically equal and IS at higher intermediate pressure when the uniform pressure rise (E1D) step IS finished. The adsorption front edge is pushed forward in the step of uniformly dropping (E1D), and the nitrogen which is easy to adsorb components in the tower is further adsorbed.
4. Mean average drop (E2D): after the step of uniform reduction (E1D), closing an outlet pressure equalizing program control valve for completing the step of uniform lifting (E1R) of the adsorption tower, opening an inlet program control valve for a fourth section pressure equalizing tank 401, communicating the adsorption tower with the fourth section pressure equalizing tank 401, putting hydrogen which is not adsorbed at higher intermediate pressure in the tower into the fourth section pressure equalizing tank 401 with slight positive pressure along the adsorption direction, and when the step of uniform reduction (E2D) is finished, keeping the pressures of the adsorption tower and the fourth section pressure equalizing tank 401 basically equal and keeping the pressures at lower intermediate pressure. In the step of averaging-down (E2D), the adsorption front advances again, and the nitrogen which is easy to be adsorbed by the adsorption component in the adsorption tower is adsorbed more thoroughly.
5. Inverse one (D1): and (3) closing the pressure equalizing program control valve at the outlet end of the adsorption tower and opening the reverse pressure releasing program control valve at the inlet end of the adsorption tower after the step of second average pressure reduction (E2D) is completed, so that the unadsorbed hydrogen in the adsorption tower is discharged to the fourth section of high-pressure buffer tank 402 in the direction opposite to the feeding direction, and the pressure in the adsorption tower is reduced to about 60KPa from the lower intermediate pressure.
6. Inverse secondary (D2): and (D1) finishing the reverse-releasing step, closing the inlet program control valve of the fourth section high-pressure buffer tank 402, and opening the inlet program control valve of the second section low-pressure buffer tank 202B, so that the unadsorbed hydrogen in the adsorption tower is discharged to the second section low-pressure buffer tank 202B in the direction opposite to the feeding direction, and the pressure in the adsorption tower is reduced to 20KPa from 60 KPa.
7. Evacuation (V): and (3) closing the reverse-discharge program control valve at the inlet end of the adsorption tower which finishes the second reverse-discharge step (D2), opening the pre-evacuation program control valve, evacuating the adsorption tower by using 2 groups of vacuum pumps to reach-90 KPa, so that nitrogen which is easy to be adsorbed components is resolved from the adsorbent, enters a fourth section of heat exchanger 404, and enters a second section of low-pressure buffer tank 202B after being reduced to normal temperature.
8. Evacuation rinse (VP): and introducing a small amount of gas from a pre-pressurization gas pipeline from the top of the adsorption tower in the evacuation (V) step to the end of the evacuation (V) step, and evacuating and flushing the adsorption tower from top to bottom so as to enhance the effect of thoroughly desorbing the adsorbed component nitrogen from the adsorbent.
9. Dimemor (E2R): finishing the step of evacuating (V), the adsorption tower has finished regeneration, but the adsorption tower at higher negative pressure must be pressurized to adsorption pressure to carry out the next adsorption operation, opening the pressure equalizing program control valve at the outlet of the adsorption tower and the inlet program control valve of the fourth section pressure equalizing tank 401, communicating the adsorption tower with the fourth section pressure equalizing tank 401, enabling the gas in the fourth section pressure equalizing tank 401 to enter the adsorption tower in the direction opposite to the adsorption direction, and when the pressure equalizing of the step of two uniform lifting (E2R) is finished, the pressure of the adsorption tower is basically equal to that of the fourth section pressure equalizing tank 401, and the adsorption tower and the fourth section pressure equalizing tank are both at lower intermediate pressure.
10. One liter (E1R): and (3) completing the adsorption tower of the step of secondary pressure equalization (E2R), closing an inlet program control valve of a pressure equalization tank 401 at the fourth section, opening an outlet pressure equalization program control valve of the adsorption tower which is performing the step of primary pressure equalization (E1D), communicating the two adsorption towers, enabling the gas of the adsorption tower which is performing the step of primary pressure equalization (E1D) to enter the adsorption tower which is performing the step of primary pressure equalization (E1R), and enabling the pressures of the two adsorption towers to be basically equal when the pressure equalization of the step of primary pressure equalization (E1R) is finished and to be at a higher intermediate pressure.
11. Final liter (FR): the adsorption column, which completed a step of one-liter (E1R), was reversely pressurized to the adsorption pressure with the outlet gas of the adsorption column in the adsorption state. The adsorption front edge can be pushed to the feeding end of the bed layer by reverse pressurizing, and the concentration front edge is flattened as much as possible, which is beneficial to the next adsorption operation. The adsorption tower completes one cycle of operation after the end of the final lift (FR) step and is ready for the next cycle of adsorption operation.
The whole operation process is carried out at the temperature of the raw material gas entering the tower.
Fourth stage pressure swing adsorption (PSA-4) Process, time Unit Table (Table 7)
Figure BSA0000171567060000241
Fourth stage pressure swing adsorption (PSA-4) Process, time Unit Table (Table 7)
Figure BSA0000171567060000242
Fourth stage pressure swing adsorption (PSA-4) Process, time Unit Table (Table 7)
Figure BSA0000171567060000243
Fourth stage pressure swing adsorption (PSA-4) Process, time Unit Table (Table 7)
Figure BSA0000171567060000244
Fourth stage pressure swing adsorption (PSA-4) Process, time Unit Table (Table 7)
Figure BSA0000171567060000251
Fourth stage pressure swing adsorption (PSA-4) Process, time and pressure gauge (Table 8)
Figure BSA0000171567060000252
The present invention has been described in an illustrative and non-restrictive manner, according to embodiments thereof, but it is to be understood that variations and/or modifications may be effected by those skilled in the art without departing from the scope of the invention as defined in the appended claims.

Claims (1)

1. A method for separating and purifying hydrogen from refining vent gas provides a four-section pressure swing adsorption gas separation device, adopts a four-section pressure swing adsorption process, and sequentially carries out the following operations:
(1) the method comprises the steps that a raw material gas enters a first-stage pressure swing adsorption (PSA-1) gas separation device after being pressurized by a compressor to perform a first-stage pressure swing adsorption process, the raw material gas firstly enters a first-stage gas-water separator to remove liquid water, then enters a first-stage desulfurizing tower to reduce the content of hydrogen sulfide in the raw material gas to less than 20ppm, then enters a first-stage adsorption tower in an adsorption state from the bottom of the first-stage adsorption tower, and easily-adsorbed components in the raw material gas, namely the easily-adsorbed components in the raw material gas, are sequentially and selectively adsorbed by adsorption bed layers of aluminum oxide, silica gel and special carbon KYAO232Part of methane, nitrogen, carbon monoxide and most of C2、C2 +The components are adsorbed, the fuel gas with high heat value obtained after desorption is sent out, and the unadsorbed fuel gas contains a large amount of nitrogen, hydrogen and a small amount of methane, carbon monoxide, carbon dioxide and C2、C2 +The first section of middle mixed gas of the components flows out from the top of the adsorption tower in an adsorption state and enters a second section of pressure swing adsorption (PSA-2) gas separation device;
when the adsorption step (A) is carried out until the adsorption front reaches the initial position of the reserved section of the outlet of the adsorption bed layer, the feeding program control valve at the bottom of the adsorption tower and the program control valve at the outlet of the top of the adsorption tower in the adsorption step (A) are closed to stop adsorption, so that a section of unused adsorbent is reserved near the top outlet end of the adsorption tower, and the adsorption front is pushed forward for use during the first average descending (E1D) and the second average descending (E2D);
cis (PP): after the step (A) of adsorption, the unadsorbed substances in the adsorption tower containing a large amount of nitrogen, hydrogen and a small amount of methane, carbon monoxide, carbon dioxide and C are absorbed along the adsorption direction2、C2 +The first section of the mixed gas of the components is put back to the raw material gas for recycling;
isolation (IS): keeping for a certain time in the state that the adsorption tower bottom feeding program control valve and the tower top outlet program control valve in the adsorption (A) step are closed to stop adsorption;
homoleptic (E1D): after the Isolation (IS) step IS finished, the unadsorbed substances in the adsorption tower containing a large amount of nitrogen, hydrogen and a small amount of methane, carbon monoxide, carbon dioxide and C are absorbed along the adsorption direction2、C2 +The mixed gas in the first section of the component is put into an adsorption tower which is in a uniform rising (E1R) step after the resolution is finished, the outlet pressure equalizing program control valves of the two adsorption towers are firstly communicated, the pressure of the two adsorption towers is equal when the pressure equalizing in the uniform falling (E1D) step is finished, the adsorption front is pushed forward in the uniform falling (E1D) step, and the components which are easy to be adsorbed in the adsorption towers, namely part of methane, nitrogen, carbon monoxide and most of C2、C2 +Components (A);
mean average drop (E2D): after the end of the step of equalizing and dropping (E1D), closeFinishing the step of uniform rising (E1R), opening the inlet program control valve of the first section of pressure equalizing tank, communicating the adsorption tower with the first section of pressure equalizing tank, and making the unadsorbed substances in the adsorption tower contain a large amount of nitrogen, hydrogen and a small amount of methane, carbon monoxide, carbon dioxide and C2、C2 +The mixed gas in the middle of the first section of the component is put into a first section of pressure equalizing tank with micro-positive pressure along the adsorption direction, the pressure of the adsorption tower is equal to that of the first section of pressure equalizing tank when the pressure equalizing in the step of two-stage reduction (E2D) is finished, the adsorption front is pushed forward again in the step of two-stage reduction (E2D), and further the components which are easy to be adsorbed in the adsorption tower, namely part of methane, nitrogen, carbon monoxide and most of C2、C2 +Adsorbing the components;
inverse one (D1): closing the pressure equalizing program control valve at the outlet end of the adsorption tower and opening the reverse release program control valve at the inlet end of the adsorption tower to ensure that the unadsorbed substances in the adsorption tower contain a large amount of nitrogen, hydrogen and a small amount of methane, carbon monoxide, carbon dioxide and C2、C2 +Discharging the first-stage intermediate mixed gas of the components to a first-stage high-pressure buffer tank in a direction opposite to the feeding direction, and reducing the pressure in the adsorption tower to 20 KPa;
inverse secondary (D2): completing the first step D1, closing the inlet program control valve of the first section high pressure buffer tank, opening the inlet program control valve of the first section low pressure buffer tank to make the unadsorbed gas in the adsorption tower contain a large amount of nitrogen, hydrogen and a small amount of methane, carbon monoxide, carbon dioxide and C2、C2 +Discharging the first-stage intermediate mixed gas of the components to a first-stage low-pressure buffer tank in a direction opposite to the feeding direction, and reducing the pressure in the adsorption tower from 20KPa to normal pressure;
evacuation (V): completing the adsorption tower in the second reverse discharge step (D2), closing the reverse discharge program control valve, switching the evacuation common program control valve, evacuating the adsorption tower by using two groups of vacuum pumps to reach-90 KPa, and allowing the components which are easy to be adsorbed, namely part of methane, nitrogen, carbon monoxide and most of C2、C2 +The components are resolved from the adsorbent, enter a first section of heat exchanger, and enter a first section of low-pressure buffer tank after being reduced to normal temperature;
evacuation flushing (VP), wherein a small amount of gas is introduced from the pre-pressure gas pipeline from the top of the adsorption tower in the evacuation (V) step to the end of the evacuation (V) step, and the adsorption tower is flushed while being evacuated from top to bottom so as to enhance the effect of thoroughly resolving the easily adsorbed components, namely part of methane, nitrogen and carbon monoxide and most of components C2 and C2+ from the adsorbent;
dimemor (E2R): the adsorption tower completing the step of evacuation and flushing (VP) is opened, an outlet pressure equalizing program control valve of the adsorption tower in the step of two uniform rises (E2R) and an inlet program control valve of a first section of pressure equalizing tank are opened, the adsorption tower is communicated with the first section of pressure equalizing tank, so that gas in the first section of pressure equalizing tank enters the adsorption tower in the direction opposite to the adsorption direction, and the pressure of the adsorption tower is equal to that of the first section of pressure equalizing tank after the pressure equalizing in the step of two uniform rises (E2R) is finished;
one liter (E1R): completing the adsorption tower of the step of secondary pressure equalization (E2R), closing an inlet program control valve of a first section of pressure equalization tank, opening an outlet pressure equalization program control valve of the adsorption tower which is performing the step of primary pressure equalization (E1D), communicating the two adsorption towers, and enabling the gas of the adsorption tower which is performing the step of primary pressure equalization (E1D) to enter the adsorption tower which is performing the step of primary pressure equalization (E1R), wherein the pressures of the two adsorption towers are equal when the pressure equalization of the step of primary pressure equalization (E1R) is finished;
final liter (FR): the adsorption tower which completes the step of uniform rising (E1R) is reversely pressurized to the adsorption pressure by using the outlet gas of the adsorption tower in the adsorption state, the adsorption front edge can be pushed to the feed end of the bed layer by the reverse pressurization, and the concentration front edge is flattened as much as possible, which is beneficial to the next adsorption operation, and the adsorption tower completes a cycle operation after the step of Final Rising (FR) is finished and is ready for the next cycle of adsorption operation;
(2) the first section of intermediate mixed gas entering a second section of pressure swing adsorption (PSA-2) gas separation device enters a second section of adsorption tower in an adsorption state from the bottom of the second section of adsorption tower to carry out a second section of pressure swing adsorption process, and the easily-adsorbed components in the first section of intermediate mixed gas, namely nitrogen, methane, carbon monoxide, carbon dioxide and C, are sequentially selected and adsorbed by activated carbon and molecular sieves in an adsorption bed layer2、C2 +The components are absorbed and returned to the raw material gas for recycling after being resolved,the unadsorbed second-stage intermediate mixed gas containing a large amount of nitrogen, hydrogen, a small amount of methane and carbon monoxide flows out from the top of the adsorption tower in an adsorption state and enters a third-stage pressure swing adsorption (PSA-3) gas separation device;
when the adsorption step (A) is carried out until the adsorption front reaches the initial position of the reserved section of the outlet of the adsorption bed layer, the feeding program control valve at the bottom of the adsorption tower and the program control valve at the outlet of the top of the adsorption tower in the adsorption step (A) are closed to stop adsorption, so that a section of unused adsorbent is reserved near the top outlet end of the adsorption tower, and the adsorption front is pushed forward for use during the first average descending (E1D) and the second average descending (E2D);
isolation (IS): keeping for a certain time in the state that the adsorption tower bottom feeding program control valve and the tower top outlet program control valve in the adsorption (A) step are closed to stop adsorption;
homoleptic (E1D): after the Isolation (IS) step IS finished, the second-stage intermediate mixed gas which IS not adsorbed in the adsorption tower and contains a large amount of nitrogen, hydrogen, a small amount of methane and carbon monoxide IS placed into an adsorption tower which IS analyzed and IS in an equalizing rise (E1R) step along the adsorption direction, the outlet pressure equalizing program control valves of the two adsorption towers are communicated, the pressure of the two adsorption towers IS equal when the equalizing rise (E1D) step IS finished, the adsorption front IS pushed forward in the equalizing fall (E1D) step, and the components which are easily adsorbed in the adsorption tower, namely nitrogen, methane, carbon monoxide, carbon dioxide and C are further adsorbed2、C2 +Components (A);
mean average drop (E2D): after the step of uniform descending (E1D), closing an outlet pressure equalizing program control valve of the adsorption tower after the step of uniform ascending (E1R), opening an inlet program control valve of a second-stage pressure equalizing tank, communicating the adsorption tower with the second-stage pressure equalizing tank to ensure that second-stage intermediate mixed gas which is not adsorbed in the adsorption tower and contains a large amount of nitrogen, hydrogen, a small amount of methane and carbon monoxide enters the second-stage pressure equalizing tank with slight positive pressure along the adsorption direction, ensuring that the pressure of the adsorption tower is equal to that of the second-stage pressure equalizing tank when the pressure equalizing of the step of uniform descending (E2D) is finished, advancing the adsorption front again in the step of uniform descending (E2D), and further ensuring that components which are easily adsorbed in the adsorption tower, namely nitrogen, methane, carbon monoxide, carbon dioxide and C are easily adsorbed2、C2 +Adsorbing the components;
inverse one (D1): closing the pressure equalizing program control valve at the outlet end of the adsorption tower and opening the reverse release program control valve at the inlet end of the adsorption tower to discharge the second-section intermediate mixed gas which is not adsorbed and contains a large amount of nitrogen, hydrogen, a small amount of methane and carbon monoxide in the adsorption tower to a second-section high-pressure buffer tank in a direction opposite to the feeding direction, and reducing the pressure in the adsorption tower to 20 KPa;
inverse secondary (D2): the adsorption tower which finishes the first step (D1) of reverse release is closed, an inlet program control valve of a second section of high-pressure buffer tank is opened, an inlet program control valve of a second section of low-pressure buffer tank is opened, so that second section intermediate mixed gas which is not adsorbed and contains a large amount of nitrogen, hydrogen, a small amount of methane and carbon monoxide in the adsorption tower is discharged to the second section of low-pressure buffer tank in the direction opposite to the feeding direction, and the pressure in the adsorption tower is reduced to 10KPa from 20 KPa;
evacuation (V): completing the adsorption tower in the second step of reverse discharge (D2), closing the inlet end reverse discharge program control valve, opening the evacuation program control valve, evacuating the adsorption tower by using two groups of vacuum pumps to reach-90 KPa, and allowing the components which are easy to be adsorbed, namely nitrogen, methane, carbon monoxide, carbon dioxide and C2、C2 +The components are resolved from the adsorbent, enter a second section of heat exchanger, and enter a second section of low-pressure buffer tank after being cooled to normal temperature;
evacuation flushing (VP) by introducing a small amount of gas from the pre-pressurizing gas pipeline from the top of the adsorption tower in the evacuation (V) step to the end of the evacuation (V) step, and flushing the adsorption tower while evacuating from top to bottom to enhance the adsorbability of the components to be adsorbed, i.e. nitrogen, methane, carbon monoxide, carbon dioxide, C2、C2 +The components are thoroughly resolved from the adsorbent;
dimemor (E2R): the adsorption tower completing the step of evacuation and flushing (VP) is opened, an outlet pressure equalizing program control valve of the adsorption tower in the step of secondary pressure equalization (E2R) and an inlet program control valve of a second section of pressure equalizing tank are opened, the adsorption tower is communicated with the second section of pressure equalizing tank, so that gas in the second section of pressure equalizing tank enters the adsorption tower in the direction opposite to the adsorption direction, and the pressure of the adsorption tower is equal to that of the second section of pressure equalizing tank after the pressure equalization in the step of secondary pressure equalization (E2R);
one liter (E1R): completing the adsorption tower of the step of secondary pressure equalization (E2R), closing an inlet program control valve of a second section of pressure equalization tank, opening a pressure equalization program control valve of the adsorption tower which is performing the step of primary pressure equalization (E1D), communicating the two adsorption towers, and enabling the gas of the adsorption tower which is performing the step of primary pressure equalization (E1D) to enter the adsorption tower which is performing the step of primary pressure equalization (E1R), wherein the pressures of the two adsorption towers are equal when the pressure equalization of the step of primary pressure equalization (E1R) is finished;
final liter (FR): the adsorption tower which completes the step of uniform rising (E1R) is reversely pressurized to the adsorption pressure by using the outlet gas of the adsorption tower in the adsorption state, the adsorption front edge can be pushed to the feed end of the bed layer by the reverse pressurization, and the concentration front edge is flattened as much as possible, which is beneficial to the next adsorption operation, and the adsorption tower completes a cycle operation after the step of Final Rising (FR) is finished and is ready for the next cycle of adsorption operation;
(3) allowing the second-stage intermediate mixed gas entering a third-stage pressure swing adsorption (PSA-3) gas separation device to enter a third-stage adsorption tower in an adsorption state from the bottom of the third-stage adsorption tower, performing a third-stage pressure swing adsorption process, adsorbing easily-adsorbed components, namely nitrogen, methane and carbon monoxide, in the second-stage intermediate mixed gas under the sequential selective adsorption of activated carbon and molecular sieves on an adsorption bed layer, sending the desorbed components out of a boundary zone as vent gas, allowing the unadsorbed third-stage intermediate mixed gas containing a large amount of hydrogen and a small amount of nitrogen to flow out of the top of the adsorption tower in the adsorption state, and allowing the unadsorbed third-stage intermediate mixed gas to enter a fourth-stage pressure swing adsorption (PSA-4) gas separation device;
when the adsorption step (A) is carried out until the adsorption front reaches the initial position of the reserved section of the outlet of the adsorption bed layer, the feeding program control valve at the bottom of the adsorption tower and the program control valve at the outlet of the top of the adsorption tower in the adsorption step (A) are closed to stop adsorption, so that a section of unused adsorbent is reserved near the top outlet end of the adsorption tower, and the adsorption front is pushed forward for use during the first average descending (E1D) and the second average descending (E2D);
isolation (IS): keeping for a certain time in the state that the adsorption tower bottom feeding program control valve and the tower top outlet program control valve in the adsorption (A) step are closed to stop adsorption;
homoleptic (E1D): after the step of Isolating (IS) IS finished, putting unadsorbed hydrogen and nitrogen in the adsorption towers into an adsorption tower which IS analyzed and IS in a step of uniformly rising (E1R) along the adsorption direction, wherein outlet pressure equalizing program control valves of the two adsorption towers are required to be communicated firstly, when the pressure equalizing of the step of uniformly falling (E1D) IS finished, the pressure of the two adsorption towers IS equal, the adsorption front IS pushed forward in the step of uniformly falling (E1D), and the easily adsorbed components in the adsorption towers, namely nitrogen, methane and carbon monoxide, are further absorbed;
mean average drop (E2D): after the step of uniform descending (E1D), closing an outlet pressure equalizing program control valve of the adsorption tower after the step of uniform ascending (E1R), opening an inlet program control valve of a third section of pressure equalizing tank, communicating the adsorption tower with the third section of pressure equalizing tank, putting unadsorbed hydrogen and nitrogen in the tower into the third section of pressure equalizing tank with slight positive pressure along the adsorption direction, enabling the pressure of the adsorption tower to be equal to that of the third section of pressure equalizing tank when the pressure equalizing of the step of uniform descending (E2D) is finished, and pushing the adsorption front forward again in the step of uniform descending (E2D) so as to more thoroughly adsorb the adsorbed components, namely nitrogen, methane and carbon monoxide, in the adsorption tower;
reverse (D): closing the pressure equalizing program control valve at the outlet end of the adsorption tower and opening the reverse discharge program control valve at the inlet end of the adsorption tower to discharge the gas in the adsorption tower to the outside in the direction opposite to the feeding direction for emptying after the adsorption tower completes the step of second average descending (E2D);
evacuation (V): closing the reverse-discharge program control valve at the inlet end of the adsorption tower after the reverse-discharge step (D) is finished, opening the pre-evacuation program control valve, evacuating the adsorption tower by using two groups of vacuum pumps to reach-90 KPa, so that the components which are easy to be adsorbed, namely nitrogen, methane and carbon monoxide are analyzed from the adsorbent and discharged to the outside for evacuation;
evacuation flushing (VP), wherein a small amount of gas is introduced from the pre-pressure gas pipeline from the top of the adsorption tower in the evacuation (V) step to the end of the evacuation (V) step, and the adsorption tower is flushed while being evacuated from top to bottom so as to enhance the effect that the components which are easy to be adsorbed, namely nitrogen, methane and carbon monoxide, are thoroughly desorbed from the adsorbent;
dimemor (E2R): finishing the step V of evacuating, finishing regeneration of the adsorption tower, but carrying out next adsorption operation only by pressurizing the adsorption tower at negative pressure to adsorption pressure, opening an outlet pressure equalizing program control valve of the adsorption tower and an inlet program control valve of a third section of pressure equalizing tank, communicating the adsorption tower with the third section of pressure equalizing tank, enabling gas in the third section of pressure equalizing tank to enter the adsorption tower in a reverse adsorption direction, and equalizing the pressure of the adsorption tower and the pressure of the third section of pressure equalizing tank when the pressure equalizing of the step E2R is finished;
one liter (E1R): completing the adsorption tower in the step of secondary pressure equalization (E2R), closing an inlet program control valve of a third section of pressure equalization tank, opening an outlet pressure equalization program control valve of the adsorption tower in the step of primary pressure equalization (E1D), communicating the two adsorption towers, enabling the gas in the adsorption tower in the step of primary pressure equalization (E1D) to enter the adsorption tower in the step of primary pressure equalization (E1R), and enabling the pressures of the two adsorption towers to be equal when the pressure equalization in the step of primary pressure equalization (E1R) is finished;
final liter (FR): the adsorption tower which completes the step of uniform rising (E1R) is reversely pressurized to the adsorption pressure by using the outlet gas of the adsorption tower in the adsorption state, the adsorption front edge can be pushed to the feed end of the bed layer by the reverse pressurization, and the concentration front edge is flattened as much as possible, which is beneficial to the next adsorption operation, and the adsorption tower completes a cycle operation after the step of Final Rising (FR) is finished and is ready for the next cycle of adsorption operation;
(4) the third section of intermediate mixed gas entering a fourth section of pressure swing adsorption (PSA-4) gas separation device enters a fourth section of adsorption tower in an adsorption state from the bottom of the fourth section of adsorption tower, a fourth section of pressure swing adsorption process is carried out, nitrogen which is easy to adsorb components in the third section of intermediate mixed gas is adsorbed under the sequential selective adsorption of special carbon KYAO232 and a molecular sieve on an adsorption bed layer, the nitrogen is returned to feed gas for recycling after being analyzed, and unadsorbed hydrogen flows out from the top of the adsorption tower in the adsorption state and is sent out of a battery compartment as a product with qualified purity;
when the adsorption step (A) is carried out until the adsorption front reaches the initial position of the reserved section of the outlet of the adsorption bed layer, the feeding program control valve at the bottom of the adsorption tower and the program control valve at the outlet of the top of the adsorption tower in the adsorption step (A) are closed to stop adsorption, so that a section of unused adsorbent is reserved near the top outlet end of the adsorption tower, and the adsorption front is pushed forward for use during the first average descending (E1D) and the second average descending (E2D);
isolation (IS): keeping for a certain time in the state that the adsorption tower bottom feeding program control valve and the tower top outlet program control valve in the adsorption (A) step are closed to stop adsorption;
homoleptic (E1D): after the step of Isolating (IS) IS finished, putting unadsorbed hydrogen in the adsorption tower into an adsorption tower which IS analyzed and IS in a step of uniformly rising (E1R) along the adsorption direction, wherein outlet pressure-equalizing program control valves of the two adsorption towers are required to be communicated firstly, when the pressure equalization of the step of uniformly falling (E1D) IS finished, the pressure of the two adsorption towers IS equal, the adsorption front IS pushed forward in the step of uniformly falling (E1D), and the nitrogen which IS easily adsorbed and IS a component in the adsorption tower IS further adsorbed;
mean average drop (E2D): after the step of uniform descending (E1D), closing an outlet pressure equalizing program control valve of the adsorption tower in the step of uniform ascending (E1R), opening an inlet program control valve of a pressure equalizing tank at the fourth section, communicating the adsorption tower with the pressure equalizing tank at the fourth section, putting unadsorbed hydrogen in the tower into the pressure equalizing tank at the fourth section with slight positive pressure along the adsorption direction, equalizing the pressure of the adsorption tower with that of the pressure equalizing tank at the fourth section when the step of uniform descending (E2D) is finished, and pushing the adsorption front forward again in the step of uniform descending (E2D) so as to more thoroughly adsorb the adsorbed components in the adsorption tower by nitrogen;
inverse one (D1): closing the pressure equalizing program control valve at the outlet end of the adsorption tower and opening the reverse release program control valve at the inlet end of the adsorption tower to discharge the unadsorbed hydrogen in the adsorption tower to a fourth section of high-pressure buffer tank in the direction opposite to the feeding direction, and reducing the pressure in the adsorption tower to 60 KPa;
inverse secondary (D2): completing the adsorption tower in the first reverse release step (D1), closing the inlet program control valve of the fourth section of high-pressure buffer tank, opening the inlet program control valve of the second section of low-pressure buffer tank, discharging unadsorbed hydrogen in the adsorption tower to the second section of low-pressure buffer tank in a direction opposite to the feeding direction, and reducing the pressure in the adsorption tower from 60KPa to 20 KPa;
evacuation (V): closing the reverse-discharge program control valve at the inlet end of the adsorption tower completing the reverse-discharge step II (D2), opening the pre-evacuation program control valve, evacuating the adsorption tower to-90 KPa by using two groups of vacuum pumps, so that nitrogen which is a component easy to be adsorbed is resolved from the adsorbent, enters a fourth section of heat exchanger, and enters a second section of low-pressure buffer tank after being reduced to normal temperature;
evacuation flushing (VP), namely introducing a small amount of gas from the pre-pressure gas pipeline from the top of the adsorption tower in the evacuation (V) step to the end of the evacuation (V) step, and flushing the adsorption tower while evacuating from top to bottom so as to enhance the effect of thoroughly resolving the adsorbed component nitrogen from the adsorbent;
dimemor (E2R): finishing the step V of evacuating, finishing regeneration of the adsorption tower, but carrying out next adsorption operation only by pressurizing the adsorption tower at negative pressure to adsorption pressure, opening an outlet pressure-equalizing program control valve of the adsorption tower and an inlet program control valve of a fourth-section pressure-equalizing tank, communicating the adsorption tower with the fourth-section pressure-equalizing tank, enabling gas in the fourth-section pressure-equalizing tank to enter the adsorption tower in a reverse adsorption direction, and equalizing the pressure of the adsorption tower and the pressure of the fourth-section pressure-equalizing tank when the pressure equalization of the step E2R is finished;
one liter (E1R): completing the adsorption tower in the step of secondary pressure equalization (E2R), closing an inlet program control valve of a pressure equalization tank at the fourth section, opening an outlet pressure equalization program control valve of the adsorption tower in the step of primary pressure equalization (E1D), communicating the two adsorption towers, enabling the gas in the adsorption tower in the step of primary pressure equalization (E1D) to enter the adsorption tower in the step of primary pressure equalization (E1R), and enabling the pressures of the two adsorption towers to be equal when the pressure equalization in the step of primary pressure equalization (E1R) is finished;
final liter (FR): the adsorption tower completing the step of uniform rising (E1R) is reversely pressurized to the adsorption pressure by using the outlet gas of the adsorption tower in the adsorption state, the adsorption front edge can be pushed to the feed end of the bed layer by the reverse pressurization, and the concentration front edge is flattened as much as possible, so that the adsorption tower is beneficial to the next adsorption operation, completes one cycle operation after the step of Final Rising (FR) is finished, and is ready for the next cycle of adsorption operation.
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