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CN116904235A - Underground coal synthesis gas treatment process based on membrane separation technology - Google Patents

Underground coal synthesis gas treatment process based on membrane separation technology Download PDF

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Publication number
CN116904235A
CN116904235A CN202310947582.3A CN202310947582A CN116904235A CN 116904235 A CN116904235 A CN 116904235A CN 202310947582 A CN202310947582 A CN 202310947582A CN 116904235 A CN116904235 A CN 116904235A
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China
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communicated
synthesis gas
molar concentration
gas
heat exchanger
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CN202310947582.3A
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Chinese (zh)
Inventor
王涛
任丹
曾丽瑶
吴佳伟
丁锋
梁莉
袁国翠
王利畏
陈清涛
高继峰
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Sinopec Oilfield Service Corp
Sinopec Zhongyuan Petroleum Engineering Design Co Ltd
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Sinopec Oilfield Service Corp
Sinopec Zhongyuan Petroleum Engineering Design Co Ltd
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Priority to CN202310947582.3A priority Critical patent/CN116904235A/en
Publication of CN116904235A publication Critical patent/CN116904235A/en
Pending legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10K—PURIFYING OR MODIFYING THE CHEMICAL COMPOSITION OF COMBUSTIBLE GASES CONTAINING CARBON MONOXIDE
    • C10K1/00—Purifying combustible gases containing carbon monoxide
    • C10K1/20—Purifying combustible gases containing carbon monoxide by treating with solids; Regenerating spent purifying masses
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10K—PURIFYING OR MODIFYING THE CHEMICAL COMPOSITION OF COMBUSTIBLE GASES CONTAINING CARBON MONOXIDE
    • C10K1/00—Purifying combustible gases containing carbon monoxide
    • C10K1/002—Removal of contaminants
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10K—PURIFYING OR MODIFYING THE CHEMICAL COMPOSITION OF COMBUSTIBLE GASES CONTAINING CARBON MONOXIDE
    • C10K1/00—Purifying combustible gases containing carbon monoxide
    • C10K1/002—Removal of contaminants
    • C10K1/003—Removal of contaminants of acid contaminants, e.g. acid gas removal
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10K—PURIFYING OR MODIFYING THE CHEMICAL COMPOSITION OF COMBUSTIBLE GASES CONTAINING CARBON MONOXIDE
    • C10K1/00—Purifying combustible gases containing carbon monoxide
    • C10K1/02—Dust removal
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10K—PURIFYING OR MODIFYING THE CHEMICAL COMPOSITION OF COMBUSTIBLE GASES CONTAINING CARBON MONOXIDE
    • C10K1/00—Purifying combustible gases containing carbon monoxide
    • C10K1/08—Purifying combustible gases containing carbon monoxide by washing with liquids; Reviving the used wash liquors
    • C10K1/10—Purifying combustible gases containing carbon monoxide by washing with liquids; Reviving the used wash liquors with aqueous liquids
    • C10K1/12—Purifying combustible gases containing carbon monoxide by washing with liquids; Reviving the used wash liquors with aqueous liquids alkaline-reacting including the revival of the used wash liquors
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10K—PURIFYING OR MODIFYING THE CHEMICAL COMPOSITION OF COMBUSTIBLE GASES CONTAINING CARBON MONOXIDE
    • C10K1/00—Purifying combustible gases containing carbon monoxide
    • C10K1/08—Purifying combustible gases containing carbon monoxide by washing with liquids; Reviving the used wash liquors
    • C10K1/10—Purifying combustible gases containing carbon monoxide by washing with liquids; Reviving the used wash liquors with aqueous liquids
    • C10K1/12—Purifying combustible gases containing carbon monoxide by washing with liquids; Reviving the used wash liquors with aqueous liquids alkaline-reacting including the revival of the used wash liquors
    • C10K1/14—Purifying combustible gases containing carbon monoxide by washing with liquids; Reviving the used wash liquors with aqueous liquids alkaline-reacting including the revival of the used wash liquors organic
    • C10K1/143—Purifying combustible gases containing carbon monoxide by washing with liquids; Reviving the used wash liquors with aqueous liquids alkaline-reacting including the revival of the used wash liquors organic containing amino groups
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10K—PURIFYING OR MODIFYING THE CHEMICAL COMPOSITION OF COMBUSTIBLE GASES CONTAINING CARBON MONOXIDE
    • C10K1/00—Purifying combustible gases containing carbon monoxide
    • C10K1/34—Purifying combustible gases containing carbon monoxide by catalytic conversion of impurities to more readily removable materials

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Combustion & Propulsion (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Organic Chemistry (AREA)
  • Separation Using Semi-Permeable Membranes (AREA)
  • Gas Separation By Absorption (AREA)

Abstract

The invention relates to a process for treating underground coal synthesis gas based on membrane separation technology, which comprises the steps of removing solid impurities, coal tar and high-temperature saturated water from crude synthesis gas through a pretreatment unit to obtain synthesis gas, and inputting the synthesis gas into a membrane separation treatment unit for multistage membrane separation to realize C0 2 、H 2 And CH (CH) 4 Is separated to obtain decarbonized gas and mixed gas, and the decarbonized gas is subjected to CO removal and N removal 2 Liquefied LNG is obtained, and the mixed gas is input into an amine method for decarbonizationUnit separation of C0 2 And H with purity not less than 99% 2 ，H 2 Recovered, and C0 2 The liquid CO is obtained through pressurization, dehydration and liquefaction 2 The method comprises the steps of carrying out a first treatment on the surface of the The invention has the advantage of improving the economic benefit of the project on the basis of realizing the advanced treatment of the underground coal synthesis gas under the complex working condition.

Description

Underground coal synthesis gas treatment process based on membrane separation technology
Technical Field
The invention belongs to the technical field of underground coal synthesis gas treatment, and particularly relates to an underground coal synthesis gas treatment process based on a membrane separation technology.
Background
Underground gasification of coal (Underground Coal Gasification, UCG) is a technique for producing H by in situ controlled combustion of coal resources buried underground 2 、CH 4 The underground coal gasification technology not only can improve the exploitation and utilization efficiency of coal resources and overcome the negative influence of coal on the environment in exploitation and application, but also provides a new strategic direction for natural gas development.
The Chinese patent publication No. CN113862044A discloses a high-efficiency ground treatment process for underground coal synthesis gas, and the technical scheme specifically discloses that the underground coal synthesis gas is pretreated by raw gas and removed by MDEAIn the technical scheme, a single activated MDEA solution absorption method is used for a decarbonization unit of the synthetic gas, an activating agent used for activating the MDEA solution has a low boiling point, the activating agent is easy to be entrained in purified gas and regenerated gas, the loss is large, if the concentration of the activating agent is too high, equipment and equipment are easy to be corroded, and in addition, due to MDEA and CO, the activating agent is easy to be carried in the purified gas and the regenerated gas 2 The absorption reaction rate is slower, the increased circulation volume of the absorption liquid can cause high energy consumption and high operation cost, and the technical scheme can only finish decarburization of the synthesis gas, cannot realize recovery of hydrogen and causes waste of resources.
The Chinese patent publication No. CN113880092A discloses a CO 2 The technical scheme particularly discloses a combined process for CO by utilizing a low-temperature rectification and adsorption separation process 2 The technical scheme mainly comprises the procedures of multistage pressurization, desulfurization, dehydration and demercuration, fractionation and recovery, and the like, but the technology has higher energy consumption and higher equipment cost.
The invention discloses an integrated device and a method for co-producing carbon monoxide, methanol, hydrogen and refined synthetic gas by using coal-made synthetic gas, and particularly discloses an integrated device for co-producing carbon monoxide, methanol, hydrogen and refined synthetic gas by using coal-made synthetic gas.
The Chinese patent publication No. CN102191086A discloses a system for coupling hydrogen purification and wax oil hydrogenation in coal-to-gas production, and the technical scheme specifically discloses a purification technology of hydrogen in coal-to-gas by a membrane separation technology, and the device can realize separation of hydrogen and carbon dioxide and efficient utilization of hydrogen, but has complex synthesis gas components (CO 2 Content of>50％、H 2 Content of>20％、CH 4 Content of>20％Coal tar, dust-containing impurities, etc.), the membrane separation system cannot realize CO 2 、H 2 、CH 4 Thereby causing waste of resources.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide the underground coal synthesis gas treatment process based on the membrane separation technology, which improves the economic benefit of the project on the basis of realizing the deep treatment of the underground coal synthesis gas under complex working conditions.
The technical scheme of the invention is as follows:
an underground coal synthesis gas treatment process based on a membrane separation technology comprises the following steps:
s1: will contain CO 2 Molar concentration>50％、H 2 Molar concentration>20％、CH 4 Molar concentration>20% of crude synthesis gas containing coal tar and dust impurities and having the temperature of more than 200 ℃ is subjected to pretreatment unit to remove solid impurities, coal tar and high-temperature saturated water to obtain synthesis gas;
s2: the synthesis gas is input into a membrane separation treatment unit to be subjected to multistage membrane separation to realize C0 2 、H 2 And CH (CH) 4 Separating to obtain decarbonized gas and mixed gas;
s3: CO and N are removed from the decarbonized gas obtained in S2 2 And liquefied to obtain LNG;
s4: inputting the mixed gas obtained in the step S2 into an amine method decarburization unit to separate C0 2 And H with purity not less than 99% 2 ，H 2 Recovered, and C0 2 The liquid CO is obtained through pressurization, dehydration and liquefaction 2 。
Further, the pressure of the synthesis gas>3MPa, temperature>25℃、CO 2 Molar concentration>50% H2 molar concentration>20％、CH 4 Molar concentration>20％。
Further, the membrane separation treatment unit comprises a first membrane component communicated with the pretreatment unit, a second membrane component communicated with the first membrane component, a first compressor communicated with the first membrane component and the second membrane component, a first heat exchanger communicated with the first compressor and a third membrane component communicated with the first heat exchanger, wherein the third membrane component is communicated with the second compressor and the second heat exchanger in series, and the first heat exchanger is communicated with the first membrane component.
Further, the first membrane component, the second membrane component and the third membrane component are polyimide hollow fiber membranes subjected to heat treatment, the treatment temperature of the heat treatment is 250-350 ℃, the treatment time is 30-120 min, and the filling density of the hollow fiber membranes is 500-9000m 2 /m 3 。
Further, the membrane separation treatment unit comprises the following treatment steps:
s51: the synthesis gas enters the membrane component I to separate a first material flow and a second material flow, wherein H in the first material flow 2 The molar concentration of (C) is 0.5-1%, CO 2 The molar concentration of (2) is 50-60%, H in the second material flow 2 The molar concentration of (C) is 55-60%, CO 2 The molar concentration of (2) is 30-39%;
s52: separating the first stream into a membrane component to obtain decarbonized gas and a third stream, wherein the CO of the decarbonized gas 2 Molar concentration is less than or equal to 3%, CH 4 The molar concentration is 80-90%, and CO in the third material flow 2 The molar concentration of (2) is 80-90%;
s53: the second material flow and the third material flow are mixed to form a fourth material flow, the fourth material flow sequentially passes through a first compressor and a first heat exchanger to obtain a fifth material flow with the pressure of 1-1.5Mpa and the temperature of 25-35 ℃, and the fifth material flow is separated by a third membrane component to obtain the H-containing material 2 And CO 2 And stream six, wherein the molar concentration of CO2 is 38-41%, H 2 The molar concentration of (2) is 56-60%;
s54: the material flow six is treated by a compressor II and a heat exchanger II in sequence to be the pressure of more than 3MPa and the temperature of more than 25 ℃ and then enters a membrane assembly I for circulation.
Further, the amine method decarburization unit comprises a third compressor, a third heat exchanger, an absorption tower, a first separator, a rich liquid flash tank, a pump, a rich lean liquid heat exchanger, a second separator, a reboiler, a regeneration tower, a third separator, a hydrogen outlet and a carbon dioxide outlet, wherein the third compressor, the third heat exchanger and the absorption tower are communicated in series, two pipelines are arranged at the bottom of the absorption tower, one pipeline is communicated with the lower part of the side wall of the absorption tower, the other pipeline is communicated with the rich liquid flash tank, the upper side surface and the lower side surface of the rich liquid flash tank are respectively communicated with the second separator and the pump, the pump is communicated with the rich lean liquid heat exchanger, the upper, middle and lower parts of the rich lean liquid heat exchanger are respectively communicated with the reboiler, the upper part of the regeneration tower and the upper part of the absorption tower, the lower part of the regeneration tower is communicated with the reboiler, the upper part of the regeneration tower is communicated with the third separator, and the second separator and the third separator are respectively communicated with the carbon dioxide outlet;
the upper part of the absorption tower is communicated with a first separator, and the separator is communicated with a hydrogen outlet.
Further, the treatment steps of the amine decarbonization unit are as follows:
s71: will contain H 2 And CO 2 The mixed gas is treated by a third compressor and a third heat exchanger until the pressure is 3-4MPa and the temperature is 30-35 ℃, and then enters the absorption tower from the lower part of the absorption tower, so that the mixed gas is in countercurrent contact with the absorbent in the process of flowing upwards from the lower part of the absorption tower;
s72: CO in the mixed gas 2 Absorbing by the absorbent to obtain rich amine liquid, wherein the rich amine liquid flows out from the bottom of the absorption tower, and the residual gas is discharged from the top of the absorption tower and passes through a first separator to obtain H with purity more than or equal to 99 percent 2 ；
S73: the rich amine liquid flowing out from the bottom of the absorption tower is divided into rich amine liquid A accounting for 20-40% of the total amount of the rich amine liquid and rich amine liquid B accounting for 60-80% of the total amount of the rich amine liquid, the rich amine liquid A enters the absorption tower again to react with raw gas, the pre-absorption of the mixed gas is realized, and the rich amine liquid B enters a rich liquid flash tank to form semi-lean liquid and CO 2 Flash vapor, CO 2 The flash steam can obtain CO with partial purity more than or equal to 99 percent after passing through a second separator 2 ；
S74: pressurizing the semi-lean solution to 3-4MPa by a pump, then entering a regeneration tower through a rich lean solution heat exchanger, regenerating the semi-lean solution into lean solution under the action of a reboiler, and entering an absorption tower for recycling, wherein the heating temperature of the reboiler is 90-110 ℃, and regenerated CO 2 Collecting at the top of the regeneration tower, wherein the temperature of the top of the tower is 40-60 ℃, and the regenerated CO 2 CO with purity more than or equal to 99% obtained by the separator 3 2 。
Further, the mass ratio of the absorbent is 0.01-0.05% PZ:0.4-0.44% MDEA:0.55% H 2 O。
Compared with the prior art, the invention has the beneficial effects that:
the invention successfully separates and obtains decarbonizing gas (CH) by using the pressure of the synthesis gas through a membrane separation treatment unit 4 Content of>80%) and contain CO 2 And H 2 Wherein CO is 2 The molar concentration of (C) is 38-41%, H 2 56-60% by mole, followed by decarbonation unit by amine method to contain CO 2 And H 2 The mixed gas of (2) is separated to respectively prepare H with the purity more than or equal to 99 percent 2 And CO with purity not less than 99% 2 Gas, while decarbonizing gas is subjected to C0 removal and N removal 2 LNG after cooling and liquefying, and CO with purity more than or equal to 99 percent 2 The gas can be used for preparing liquid CO 2 Product H 2 The device can be used as clean energy for continuous use, so that the economic benefit of the project is improved on the basis of advanced treatment of underground coal synthesis gas under complex working conditions, and compared with the traditional treatment route, the device has the advantages of low construction cost and low running cost;
in a word, the invention has the advantage of improving the economic benefit of the project on the basis of realizing the advanced treatment of the underground coal synthesis gas under the complex working condition.
Drawings
FIG. 1 is a process flow diagram of the present invention;
FIG. 2 is a process flow diagram of the membrane separation processing unit of FIG. 1 according to the present invention;
FIG. 3 is a process flow diagram of the amine decarbonization unit of FIG. 1 of the present invention.
In the figure, 1, a first membrane component, 2, a second membrane component, 3, a second heat exchanger, 4, a second compressor, 5, a third membrane component, 6, a first heat exchanger, 7, a first compressor, 8, a third compressor, 9, a third heat exchanger, 10, a first separator, 11, a third separator, 12, a regeneration tower, 13, a reboiler, 14, a lean-rich liquid heat exchanger, 15, a pump, 16, a rich liquid flash tank, 17, a second separator, 18, an absorption tower, 19, a hydrogen outlet, 20 and a carbon dioxide outlet.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
As shown in fig. 1, a process for treating underground coal synthesis gas based on membrane separation technology comprises the following steps:
s1: will contain CO 2 Molar concentration>50％、H 2 Molar concentration>20％、CH 4 Molar concentration>20% of crude synthesis gas containing coal tar and dust impurities and having the temperature of more than 200 ℃ is subjected to pretreatment unit to remove solid impurities, coal tar and high-temperature saturated water to obtain synthesis gas;
s2: the synthesis gas is input into a membrane separation treatment unit to be subjected to multistage membrane separation to realize C0 2 、H 2 And CH (CH) 4 Separating to obtain decarbonized gas and mixed gas;
s3: CO and N are removed from the decarbonized gas obtained in S2 2 And liquefied to obtain LNG;
s4: inputting the mixed gas obtained in the step S2 into an amine method decarburization unit to separate C0 2 And H with purity not less than 99% 2 ，H 2 Recovered, and C0 2 The liquid CO is obtained through pressurization, dehydration and liquefaction 2 。
The above steps utilize the pressure of the raw synthesis gas itself to successfully separate and obtain decarburization purified gas (CH) through a membrane separation treatment unit 4 Content of>80%) and contain CO 2 And H 2 Of (wherein CO) 2 The molar concentration of (C) is 38-41%, H 2 56-60% by mole) followed by decarbonation unit by amine method to contain CO 2 And H 2 The mixed gas of (2) is separated to respectively prepare H with the purity more than or equal to 99 percent 2 And CO with purity not less than 99% 2 The gas can be fed into a cold box for producing LNG after simple treatment, and the purity of CO is more than or equal to 99 percent 2 The gas can be used for preparingLiquid CO 2 Product H 2 The device can be used as clean energy for continuous use, has lower construction cost and lower operation cost compared with devices required by the traditional treatment route, and improves the economic benefit of projects on the basis of advanced treatment of underground coal synthesis gas under complex working conditions.
In this embodiment, as shown in fig. 2, the membrane separation treatment unit includes a first membrane module 1 connected to the pretreatment unit via a pipeline, a second membrane module 2 connected to the first membrane module 1 via a pipeline, a first compressor 7 connected to the first membrane module 1 and the second membrane module 2 via a pipeline, a first heat exchanger 6 connected to the first compressor 7 via a pipeline, and a third membrane module 5 connected to the first heat exchanger 6 via a pipeline, wherein the third membrane module 5 is connected in series with the second compressor 4 and the second heat exchanger 3 via a pipeline, the third heat exchanger 3 is connected to the first membrane module 1 via a pipeline, the first membrane module 1, the second membrane module 2, and the third membrane module 5 are Polyimide (PI) hollow fiber membranes subjected to heat treatment, the heat treatment temperature is 250-350 ℃, the treatment time is 30-120 min, and the filling density of the hollow fiber membranes is 500-9000m 2 /m 3 ；
The membrane separation treatment unit comprises the following treatment steps:
s51: the synthesis gas enters the membrane component I1 to separate a stream I and a stream II, wherein H in the stream I 2 The molar concentration of (C) is 0.5-1%, CO 2 The molar concentration of (2) is 50-60%, H in the second material flow 2 The molar concentration of (C) is 55-60%, CO 2 The molar concentration of (2) is 30-39%;
s52: separating the first stream into a second membrane component 2 to obtain decarbonized gas and a third stream, wherein the CO of the decarbonized gas 2 Molar concentration is less than or equal to 3%, CH 4 The molar concentration is 80-90%, and CO in the third material flow 2 The molar concentration of (2) is 80-90%;
s53: the second material flow and the third material flow are mixed to form a fourth material flow, the fourth material flow sequentially passes through a first compressor 7 and a first heat exchanger 6 to obtain a fifth material flow with the pressure of 1-1.5Mpa and the temperature of 25-35 ℃, and the fifth material flow is separated by a third membrane component 5 to obtain the H-containing material 2 And CO 2 And stream six, wherein C O2 The molar concentration of (2) is 38-41%,H 2 the molar concentration of (2) is 56-60%;
s54: the material flow six is treated into pressure of more than 3MPa and temperature of more than 25 ℃ by a second compressor 4 and a second heat exchanger 3 in sequence and then enters a first membrane module for 1 cycle.
In this embodiment, as shown in fig. 3, the amine decarbonizing unit includes a third compressor 8, a third heat exchanger 9, an absorption tower 18, a first separator 10, a rich liquid flash tank 16, a pump 15, a rich lean liquid heat exchanger 14, a second separator 17, a reboiler 13, a regeneration tower 12, a third separator 11, a hydrogen outlet 19 and a carbon dioxide outlet 20, wherein the third compressor 8, the third heat exchanger 9 and the absorption tower 18 are connected in series through pipelines, two pipelines are arranged at the bottom of the absorption tower 18, one pipeline is connected to the lower side wall of the absorption tower 18, the other pipeline is connected to the rich liquid flash tank 16, the upper side surface and the lower side surface of the rich liquid flash tank 16 are respectively connected to the second separator 17 and the pump 15 through pipelines, the pump 15 is respectively connected to the rich lean liquid heat exchanger 14 through pipelines, the upper, the middle lower three parts of the rich lean liquid heat exchanger 14 are respectively connected to the reboiler 13, the upper part of the regeneration tower 12 is connected to the upper part of the absorption tower 18 through pipelines, the upper part of the regeneration tower 12 is connected to the reboiler 13 through pipelines, the upper part of the regeneration tower 12 is connected to the separator 11 through pipelines, the upper part of the reboiler 12 is connected to the separator 11 and the separator 17 is connected to the carbon dioxide outlet 20 through the third separator 17;
the upper part of the absorption tower 18 is communicated with the first separator 10 through a pipeline, and the first separator 10 is communicated with the hydrogen outlet 19 through a pipeline.
The treatment steps of the amine decarbonization unit are as follows:
s71: will contain H 2 And CO 2 After the mixed gas is treated by a third compressor 8 and a third heat exchanger 9 until the pressure is 3-4MPa and the temperature is 30-35 ℃, the mixed gas enters the absorption tower 18 from the lower part of the absorption tower 18, so that the mixed gas is in countercurrent contact with the absorbent in the process of flowing upwards from the lower part of the absorption tower 18;
s72: CO in the mixed gas 2 Absorbing by the absorbent to obtain rich amine liquid, wherein the rich amine liquid flows out from the bottom of the absorption tower 18, and the residual gas is discharged from the top of the absorption tower 18 and passes through the first separator 10 to obtain H with the purity more than or equal to 99 percent 2 ；
S73: self-supportingThe rich amine liquid flowing out from the bottom of the absorption tower 18 is divided into rich amine liquid A accounting for 20-40% of the total amount of the rich amine liquid and rich amine liquid B accounting for 60-80% of the total amount of the rich amine liquid, the rich amine liquid A enters the absorption tower 18 again to react with raw gas, the pre-absorption of the mixed gas is realized, and the rich amine liquid B enters the rich liquid flash tank 16 to form semi-lean liquid and CO 2 Flash vapor, CO 2 The flash steam can obtain CO with partial purity more than or equal to 99 percent after passing through the second separator 17 2 ；
S74: the semi-lean solution is pressurized to 3-4MPa by a pump and then enters a regeneration tower 12 through a rich lean solution heat exchanger 14, the semi-lean solution is regenerated into lean solution under the action of a reboiler 13 and enters an absorption tower 18 for recycling, wherein the heating temperature of the reboiler 13 is 90-110 ℃, and the regenerated CO 2 Collecting at the top of the regeneration tower 12, wherein the temperature of the top of the tower is 40-60 ℃, and regenerated CO 2 CO with purity more than or equal to 99% obtained by the separator 3 2 。
In the embodiment, the mass ratio of the absorbent is 0.01-0.05% PZ:0.4-0.44% MDEA:0.55% H 2 O, wherein PZ is: the carbonic anhydride catalyst, MDEA is: alcohol amine.
Example 2:
as shown in fig. 1-3, a process for treating underground coal synthesis gas based on membrane separation technology comprises the following steps:
S1：CO 2 content of>50％、H 2 Content of>20％、CH 4 Content of>20 percent of crude synthesis gas containing coal tar, dust impurities and having the temperature of more than 200 ℃ is pretreated by a pretreatment unit to remove solid impurities, coal tar and high-temperature saturated water to obtain the pressure of 3.35MPa and H 2 Synthesis gas with a content of 20.66%;
s2: separating a first stream and a second stream sequentially through a first membrane component 1, wherein CH in the first stream 4 ：30.04％，CO 2 ：57.25％，H 2 :0.83%, CH in stream two 4 ：0.84％，CO 2 ：36.3％，H 2 ：62.2％；
S3: the second material flow enters the membrane component 2 to obtain decarbonized gas and a third material flow, and the obtained second material flow is mixed with the third material flow to form a fourth material flow, and the fourth material flow entersThe mixture enters a membrane module III 5 for continuous separation, and the synthesis gas of a material flow IV is separated by the membrane module III 5 to obtain crude CO 2 Gas (CO) 2 : 93.3%) and contain CO 2 And H 2 Is composed of CO 2 ：40.38％，H 2 : 59.46%) and basically realize CO 2 /H 2 And CH (CH) 4 Wherein H is 2 The recovery rate was 99.5%, and the energy consumption required for the system was 0.27 kW.h/Nm 3.
S4: the CO is obtained after membrane separation 2 And H 2 Is composed of CO 2 ：40.38％，H 2 : 59.46%) is separated by an alcohol amine absorption unit to obtain hydrogen with purity more than or equal to 99%, when the reflux amount of the semi-lean solution is 30%, the minimum heat load of regeneration is 20710kW, and the energy consumption is 0.317 kW.h/Nm < 3 >.
Although the present invention has been described with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments described, or equivalents may be substituted for elements thereof, and any modifications, equivalents, improvements and changes may be made without departing from the spirit and principles of the present invention.

Claims (8)

1. An underground coal synthesis gas treatment process based on a membrane separation technology comprises the following steps:
s1: will contain CO 2 Molar concentration>50％、H 2 Molar concentration>20％、CH 4 Molar concentration>20% of crude synthesis gas containing coal tar and dust impurities and having the temperature of more than 200 ℃ is subjected to pretreatment unit to remove solid impurities, coal tar and high-temperature saturated water to obtain synthesis gas;
s2: the synthesis gas is input into a membrane separation treatment unit to be subjected to multistage membrane separation to realize C0 2 、H 2 And CH (CH) 4 Separating to obtain decarbonized gas and mixed gas;
s3: CO and N are removed from the decarbonized gas obtained in S2 2 And liquefied to obtain LNG;
s4: inputting the mixed gas obtained in the step S2 into an amine method for removingSeparation of C0 from carbon units 2 And H with purity not less than 99% 2 ，H 2 Recovered, and C0 2 The liquid CO is obtained through pressurization, dehydration and liquefaction 2 。
2. The underground coal synthesis gas treatment process based on membrane separation technology according to claim 1, wherein: the pressure of the synthesis gas>3MPa, temperature>25℃、CO 2 Molar concentration>50% H2 molar concentration>20％、CH 4 Molar concentration>20％。
3. The underground coal synthesis gas treatment process based on membrane separation technology according to claim 2, wherein: the membrane separation treatment unit comprises a first membrane component (1) communicated with the pretreatment unit, a second membrane component (2) communicated with the first membrane component (1), a first compressor (7) communicated with the first membrane component (1) and the second membrane component (2), a first heat exchanger (6) communicated with the first compressor (7) and a third membrane component (5) communicated with the first heat exchanger (6), wherein the third membrane component (5) is communicated with the second compressor (4) and the second heat exchanger (3) in series, and the first heat exchanger (3) is communicated with the first membrane component (1).
4. A process for treating underground coal synthesis gas based on membrane separation technology according to claim 3, wherein: the first membrane component (1), the second membrane component (2) and the third membrane component (5) are Polyimide (PI) hollow fiber membranes subjected to heat treatment, the heat treatment temperature is 250-350 ℃, the treatment time is 30-120 min, and the filling density of the hollow fiber membranes is 500-9000m 2 /m 3 。
5. The underground coal synthesis gas treatment process based on the membrane separation technology according to claim 4, wherein: the membrane separation treatment unit comprises the following treatment steps:
s51: the synthesis gas enters a membrane component I (1) to separate a material flow I and a material flow II, wherein H in the material flow I 2 The molar concentration of (C) is 0.5-1%, CO 2 The molar concentration of (2) is 50-60%, H in the second material flow 2 The molar concentration of (C) is 55-60%, CO 2 The molar concentration of (2) is 30-39%;
s52: separating decarbonized gas and a third stream from the first stream which enters the second membrane component (2), wherein CO of the decarbonized gas 2 Molar concentration is less than or equal to 3%, CH 4 The molar concentration is 80-90%, and CO in the third material flow 2 The molar concentration of (2) is 80-90%;
s53: the second material flow and the third material flow are mixed to form a fourth material flow, the fourth material flow sequentially passes through a first compressor (7) and a first heat exchanger (6) to obtain a fifth material flow with the pressure of 1-1.5Mpa and the temperature of 25-35 ℃, and the fifth material flow is separated by a third membrane component (5) to obtain the H-containing material 2 And CO 2 And stream six, wherein CO 2 The molar concentration of (C) is 38-41%, H 2 The molar concentration of (2) is 56-60%;
s54: the material flow six is processed into pressure of more than 3MPa and temperature of more than 25 ℃ by a second compressor (4) and a second heat exchanger (3) in sequence and then enters a first membrane module (1) for circulation.
6. The underground coal synthesis gas treatment process based on membrane separation technology according to claim 1, wherein: the amine method decarburization unit comprises a compressor III (8), a heat exchanger III (9), an absorption tower (18), a separator I (10), a rich liquid flash tank (16), a pump (15), a rich lean liquid heat exchanger (14), a separator II (17), a reboiler (13), a regeneration tower (12), a separator III (11), a hydrogen outlet (19) and a carbon dioxide outlet (20), wherein the compressor III (8), the heat exchanger III (9) and the absorption tower (18) are communicated in series, two pipelines are arranged at the bottom of the absorption tower (18), one pipeline is communicated with the lower side wall of the absorption tower (18), the other pipeline is communicated with the rich liquid flash tank (16), the upper side surface and the lower side surface of the rich liquid flash tank (16) are respectively communicated with the separator II (17) and the pump (15), the pump (15) is communicated with the rich lean liquid heat exchanger (14), the upper part, the middle part and the lower part of the rich lean liquid heat exchanger (14) are respectively communicated with the reboiler (13), the upper part of the regeneration tower (12) and the upper part of the absorption tower (18), one pipeline is communicated with the lower part of the regeneration tower (12), and the lower part of the regeneration tower (12) is communicated with the separator III (11), and the separator II (11) is communicated with the separator III;
the upper part of the absorption tower (18) is communicated with a first separator (10), and the separator (10) is communicated with a hydrogen outlet (19).
7. The underground coal synthesis gas treatment process based on membrane separation technology according to claim 6, wherein: the treatment steps of the amine decarbonization unit are as follows:
s71: will contain H 2 And CO 2 After the mixed gas is processed by a third compressor (8) and a third heat exchanger (9) to the pressure of 3-4MPa and the temperature of 30-35 ℃, the mixed gas enters an absorption tower (18) from the lower part of the absorption tower (18), so that the mixed gas is in countercurrent contact with an absorbent in the process of flowing upwards from the lower part of the absorption tower (18);
s72: CO in the mixed gas 2 Absorbing by the absorbent to obtain rich amine liquid, wherein the rich amine liquid flows out from the bottom of the absorption tower (18), and the residual gas is discharged from the top of the absorption tower (18) and passes through the first separator (10) to obtain H with the purity more than or equal to 99 percent 2 ；
S73: the rich amine liquid flowing out from the bottom of the absorption tower (18) is divided into rich amine liquid A accounting for 20-40% of the total amount of the rich amine liquid and rich amine liquid B accounting for 60-80% of the total amount of the rich amine liquid, the rich amine liquid A enters the absorption tower (18) again to react with raw gas, the pre-absorption of the mixed gas is realized, and the rich amine liquid B enters a rich liquid flash tank (16) to form semi-lean liquid and CO 2 Flash vapor, CO 2 The flash steam can obtain CO with partial purity more than or equal to 99 percent after passing through a second separator (17) 2 ；
S74: the semi-lean solution is pressurized to 3-4MPa by a pump and then enters a regeneration tower (12) through a rich lean solution heat exchanger (14), the semi-lean solution is regenerated into lean solution under the action of a reboiler (13) and enters an absorption tower (18) for recycling, wherein the heating temperature of the reboiler (13) is 90-110 ℃, and the regenerated CO 2 Collecting at the top of the regeneration tower (12), wherein the temperature of the top of the tower is 40-60 ℃, and regenerated CO 2 CO with purity more than or equal to 99% obtained by the separator 3 2 。
8. The underground coal synthesis gas treatment process based on membrane separation technology according to claim 7, wherein: the absorbent is ofThe mass ratio is 0.01-0.05%PZ:0.4-0.44% MDEA:0.55% H 2 O。
CN202310947582.3A 2023-07-29 2023-07-29 Underground coal synthesis gas treatment process based on membrane separation technology Pending CN116904235A (en)

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