CN113019071A - High CO2Recycled semi-barren solution circulation low-temperature methanol washing process - Google Patents

High CO2Recycled semi-barren solution circulation low-temperature methanol washing process Download PDF

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CN113019071A
CN113019071A CN202110265939.0A CN202110265939A CN113019071A CN 113019071 A CN113019071 A CN 113019071A CN 202110265939 A CN202110265939 A CN 202110265939A CN 113019071 A CN113019071 A CN 113019071A
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methanol
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管国锋
陈远
万辉
王磊
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Nanjing Tech University
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation 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
    • B01D53/14—Separation 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 absorption
    • B01D53/1425—Regeneration of liquid absorbents
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation 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
    • B01D53/14—Separation 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 absorption
    • B01D53/1418—Recovery of products
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation 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
    • B01D53/14—Separation 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 absorption
    • B01D53/1456—Removing acid components
    • B01D53/1468—Removing hydrogen sulfide
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation 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
    • B01D53/14—Separation 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 absorption
    • B01D53/1456—Removing acid components
    • B01D53/1475—Removing carbon dioxide
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/50—Carbon dioxide
    • 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
    • C10K1/002—Removal of contaminants
    • C10K1/003—Removal of contaminants of acid contaminants, e.g. acid gas removal
    • C10K1/004—Sulfur containing contaminants, e.g. hydrogen sulfide
    • 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
    • C10K1/005—Carbon dioxide
    • 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
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/151—Reduction of greenhouse gas [GHG] emissions, e.g. CO2
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals

Abstract

The invention relates to a high CO2A recycled semi-barren solution circulation low-temperature methanol washing process belongs to the field of gas purification in coal chemical industry. The apparatus involved in the process comprises an absorption column (T01), a medium pressure flash column (T02), CO2Desorber (T03), N2Stripper (T04) and methanol/CO2Flash tank (V01). On one hand, the process simultaneously feeds the sulfur-rich methanol and the carbon-rich methanol into a low-pressure desorption tower to desorb most of CO2Compared with the prior art CO2The recovery amount is increased by 65-85%, the carbon emission is reduced, and the environment is protected; on the other hand, on the basis of the absorption of the original pure barren solution, the semi-barren solution is added as the main washing methanol to be sent back to the fine decarburization section of the absorption tower for recyclingReducing the consumption of lean methanol by 30-50 percent, reducing the load of a thermal regeneration tower and N2The air stripping amount saves energy.

Description

High CO2Recycled semi-barren solution circulation low-temperature methanol washing process
Technical Field
The invention relates to a high CO2A recycled semi-barren solution circulation low-temperature methanol washing process belongs to the field of gas purification in coal chemical industry.
Background
With the development of economy, the total energy consumption of China in recent years is increased year by year, and the consumption of coal resources accounts for more than 50%. The coal chemical industry mainly comprises coal gasification, liquefaction, dry distillation, tar processing, calcium carbide acetylene chemical industry and the like. The gasification of coal plays an important role in coal chemical industry, is used for producing various gas fuels, and is clean energy. Some impurity gases are inevitably generated in the process of producing gas from coal. Therefore, gas cleaning is an important part of the coal chemical industry.
In the coal chemical industry, CO is mainly purified2、H2S, COS from CO and H2Separated and recovered. The low-temperature methanol washing method is a process capable of simultaneously finishing the decarbonization and the desulfurization, has the advantages of high efficiency and economy, and is widely applied to the gas purification industry of the coal chemical industry.
A conventional low-temperature methanol washing scheme is shown in FIG. 1, and is roughly as follows, wherein synthesis gas enters from the bottom of an absorption tower T01, purified gas is obtained from the top of the tower, and the upper part of the tower absorbs CO by using lean methanol2Middle part of the catalyst absorbs H by carbon-containing methanol2And S, absorbing impurities such as water and the like at the bottom by utilizing sulfur-containing rich methanol. Feeding the carbon-rich methanol at the bottom of the crude decarbonization section of the absorption tower T01 and the sulfur-rich methanol at the bottom of the desulfurization section into a medium-pressure flash tower T02, and extracting H from the top of the tower2The gases such as CO are sent back to the bottom of the pre-washing section of the absorption tower T01, and the liquid at the bottom of the tower respectively enters into the CO2Desorption columns T03 and N2Stripper T04. CO22Introducing the rich methanol at the bottom of the desorber T03 into N2Stripping column T04 with N at the bottom of T042Enhancement of CO2Desorption of and H2S is concentrated, sulfur-rich methanol extracted from the tower bottom enters a subsequent methanol thermal regeneration tower, poor methanol generated by thermal regeneration returns to the top of an absorption tower T01 for cyclic utilization after heat exchange, and gas extracted from the top of the thermal regeneration tower is condensed and flashed to recover H2S。
The above-mentioned traditional low temperature methanol washing process has the following disadvantages:
(1) the absorption tower only adopts poor methanol as an absorbent, which not only increases the consumption of methanol, but also causes the load of the following thermal regeneration tower to be greatly increased, and the required energy consumption is higher.
(2) To ensure CO2Sulfur content in recovered gasThe amount reaches the standard and the energy consumption is saved, and the desorption tower can only partially recover CO in the methanol-rich solution2Reduce CO2The carbon emission is increased.
Disclosure of Invention
In order to overcome the defects of the traditional low-temperature methanol washing process, the invention mainly aims to provide a high-CO methanol washing process2The recovered semi-barren solution is circulated and washed by low-temperature methanol.
In order to achieve the purpose of the invention, the technical scheme adopted by the invention is as follows:
semi-barren solution absorption and high CO2The low-temperature methanol washing process of yield is characterized in that devices involved in the process comprise an absorption tower T01, a medium-pressure flash tower T02, CO2Desorption tower T03, N2Stripper T04 and methanol/CO2Flash tank V01;
wherein the absorption tower T01 is divided into four sections, which are respectively a prewashing section 1, a desulfurizing section 2, a rough decarburization section 3 and a fine decarburization section 4 from bottom to top, purified gas B is discharged from the top of the fine decarburization section, and a bottom solution enters the upper part of the rough decarburization section after heat exchange; the carbon-rich methanol J1 of the absorption tower at the bottom of the coarse decarburization section 3 of the absorption tower is divided into three streams, one stream is sent to a prewashing section 1 of the absorption tower, the other stream is refluxed to the upper part of a desulfurization section 2 of the absorption tower after heat exchange, and the last stream is sent to an upper section 6 of a medium-pressure flash tower; sending the sulfur-rich methanol K at the bottom of the desulfurization section 2 of the absorption tower to the lower section of the medium-pressure flash tower; and (4) sending the tower bottom wastewater D of the prewashing section to a wastewater treatment tower.
The medium-pressure flash tower T02 is divided into a lower section 5 of the medium-pressure flash tower and an upper section 6 of the medium-pressure flash tower from bottom to top, the sulfur-rich methanol and the carbon-rich methanol in the absorption tower are subjected to sectional flash evaporation, and a small amount of CO and H in the methanol-rich solution are recovered2And the top gas of the upper section is connected with the bottom of the absorption tower and is used for recovering the feed gas A. Sending the sulfur-rich methanol at the bottom of the lower section 5 of the medium-pressure flash tower to CO2The lower section of the desorption tower; the carbon-rich methanol J2 at the bottom of the upper section 6 of the medium-pressure flash tower is divided into two parts, one part is sent to CO2The upper section of a desorber T03 is fed with the other stream to CO2The lower section of a desorption tower T03;
said CO2The desorber T03 divides into CO from bottom to top2Lower section of desorber 7 and CO2Upper section of desorber with 8 two stages, CO2Feeding the rich methanol at the bottom of the lower section 7 of the desorption tower into N2An upper section of a stripper column; CO22The semi-barren solution methanol at the bottom of the upper section 8 of the desorption tower is divided into two parts, one part of the semi-barren solution methanol M and the barren solution methanol C are sent to the top of the fine decarbonization section 4 of the absorption tower, and the other part is sent to N2An upper section of stripper column T04;
N2the stripper column T04 is divided into two sections, from bottom to top, N2Lower section 9 and N of the stripper2The upper section 10 of the stripping tower, the gas at the top of the upper section is sent to a wastewater washing tower, and the liquid at the bottom of the tower is sent to V01 for flash evaporation; feeding the lower-stage overhead gas into N2The solution at the bottom of the upper tower section of the stripping tower is sent to a methanol dehydration tower.
The methanol/CO2Flash tank V01 located in CO2Desorption columns T03 and N2Between stripper columns T04. Flash tank V01 top gas entering CO2The bottom of the lower section of the desorption tower, the bottom liquid and N2The lower section of the gas stripping tower is connected to desorb CO preliminarily2The carbon-rich methanol is further flashed to improve CO2The recovery amount of (1).
Preferably, carbon-rich methanol accounting for 0.2 to 0.6 percent of the molar content of the carbon-rich methanol J1 in the absorption tower flows back to the prewashing section of the absorption tower; carbon-rich methanol accounting for 24.8-39.4% of the molar content of the carbon-rich methanol J1 in the absorption tower flows back to a desulfurization section of the absorption tower, and carbon-rich methanol accounting for 60.0-75.0% of the molar content of the carbon-rich methanol J1 in the absorption tower enters an upper section of a medium-pressure flash tower; wherein H in the carbon-rich methanol2The molar content of S is 1X 10-7～1×10-6。
Preferably, the carbon-rich methanol with 70 to 85 percent of the molar content of the carbon-rich methanol J2 in the medium-pressure flash tower is sent to CO2The upper section 8 of the desorption tower, the residual solution is sent into CO2The lower section 7 of the desorption tower absorbs sulfur in the gas; wherein the pressure range of the lower section 5 of the medium-pressure flash tower is 0.5MPa to 1MPa, the pressure range of the upper section 6 of the medium-pressure flash tower is 1MPa to 3MPa, and the temperature range is-40 ℃ to-20 ℃.
Preferably, the semi-barren solution methanol at the bottom of the upper section of the CO2 desorption tower is sent to the top of the fine decarbonization section of the absorption tower for recycling, wherein the molar ratio of the semi-barren solution methanol M to the barren solution methanol C is (0.4:1) - (1.2: 1); the mol content of CO2 in the semi-barren solution methanol is 7.0-11.5%.
Preferably, the pressure of the methanol/CO 2 flash tank (V01) is in the range of 0.05MPa to 0.5MPa, and the temperature is in the range of-50 ℃ to-25 ℃.
In the traditional process, only a part of sulfur-rich methanol at the bottom of a desulfurization section of an absorption tower is sent to a desorption tower, and part of CO2 is desorbed; and the liquid at the bottom of the desorption tower completely enters an N2 stripping tower and then enters a methanol thermal regeneration tower, so that the obtained lean methanol is returned to the top of the absorption tower for recycling, and the absorption is not promoted by adopting semi-lean liquid circulation, so that the energy is wasted.
Has the advantages that:
(1) firstly, respectively extracting rich methanol at the bottoms of a decarbonization section and a desulfurization section of an absorption tower, feeding the rich methanol into the upper section of a medium-pressure flash tower, feeding the rich methanol into the lower section of the medium-pressure flash tower, carrying out flash evaporation in sections, and recovering a small amount of CO and H remained in a rich methanol solution2；
(2) Then, dividing the carbon-rich methanol at the bottom of the medium-pressure flash tower into two parts, and feeding one part into the upper section of a desorption tower for CO2Recovering gas, and feeding the rest to the lower stage for absorbing sulfur in gas to ensure CO2The sulfur content in the recovered gas is less than 10ppm, and simultaneously the sulfur-rich methanol is also sent to the lower section of the desorption tower to carry out full desorption on the sulfur-rich methanol and the carbon-rich methanol, thereby increasing CO2The carbon emission is reduced while the yield is increased;
(3) then, the desorption tower is divided into two sections, most of the half-barren solution methanol obtained in the upper section is sent to the top of the absorption tower for recycling, and the rest is sent to N2The stripping tower is used for removing sulfur in waste gas, and the lower-stage tower bottom rich methanol is also fed into N2The upper section of the stripper desorbs the waste gas, thereby reducing the entering N2The amount of methanol in the stripping column and the thermal regeneration column, the load on the thermal regeneration column and the stripping N2The consumption of the absorbent, namely the consumption of poor methanol and the energy consumption are saved;
(4) finally, adding a flash tank, N will be passed2Stripping of CO from a stripper2The carbon-rich methanol is further flashed to improve CO2And (4) recovering amount.
(5) The enthalpy value of the absorption tower of the traditional full lean solution flow and the absorption tower of the semi-lean solution flow provided by the invention are compared, and the enthalpy value difference of inlet and outlet streams needs to be balanced by cold outside the system, so that the enthalpy value difference can reflect the energy consumption of a local flow, and the result is shown in table 1.
Drawings
FIG. 1 is a flow diagram of a conventional low temperature methanol wash process;
FIG. 2 is a flow chart of the novel low temperature methanol washing process provided by the present invention;
wherein: t01: absorber, T02: medium pressure flash column, T03: CO22Desorber, T04: n is a radical of2Stripper, V01: methanol/CO2Flash tank, a: raw material gas, B: purified gas, C: lean methanol, D: wastewater, E: CO22Product gas, F: exhaust gas, G: dehydration column overhead gas, H: nitrogen, I: n is a radical of2Stripper bottoms sulfur-rich methanol, J1: absorber carbon-rich methanol, J2: medium-pressure flash tower carbon-rich methanol, K: sulfur-rich methanol, L: circulating gas, M: semi-lean methanol, 1: absorber prewashing section, 2: absorber desulfurization section, 3: crude decarbonization section of absorption tower, 4: fine decarburization section of the absorption tower, 5: lower section of medium pressure flash column, 6: upper section of medium-pressure flash column, 7: CO22Lower section of desorption column, 8: CO22Upper section of desorber, 9: n is a radical of2Lower section of the stripper, 10: n is a radical of2And an upper section of the stripper column.
Detailed Description
The present invention will be described in further detail with reference to examples. But the embodiments of the present invention are not limited thereto and conventional techniques may be referenced for process parameters not noted.
Comparative example 1
At 40 ℃, 3.08MPa, 17797.8kmol/H contains 20.35% of CO and 44.05% of H2，34.92％CO2，0.15％H2S，0.01％COS，0.31％N2，0.12％H2Raw material gas of O and 0.08 percent AR enters from the bottom of T01 tower for desulfurization and decarburization after heat exchange, and 11487.4kmol/H containing 31.29 percent of CO and 68.07 percent of H is obtained at the top of the tower2，0.02％CO2，0.48％N20.13% AR and a purge gas having a total sulfur content of less than 0.1 ppm. T01 rich methanol is sent to T02 to flash off part of CO, H2And CO2Then, the overhead gas is fed to the bottom of an absorption tower T01 for reabsorption, and the bottom liquid is fed to CO2The flash column T03 was desorbed to yield 2429.6kmol/H containing 0.58% CO, 0.44% H2，98.74％CO2，0.23％CH3OH and less than 10ppmH2S is recycled gas. The bottom liquid of T03 is fed into T04 for H2Concentrating S, and thermally regenerating in a methanol thermal regeneration tower to obtain 38000.0kmol/H containing 0.05% H2O，99.95％CH3OH-poor methanol is sent to the top of T01 tower to be used as a circulating absorbent, and H with the content of more than 25 percent is obtained at the top of the tower2The S gas is sent to the claus system.
Example 1
At 40 ℃, 3.08MPa, 17797.8kmol/H contains 20.35% of CO and 44.05% of H2，34.92％CO2，0.15％H2S，0.01％COS，0.31％N2，0.12％H2Raw material gas of O, 0.08% AR enters from the bottom of T01 tower to be desulfurized and decarbonized after heat exchange, and 43251.6kmol/H H of the bottom of fine decarbonization section tower2The molar content of S is 1X 10-739.4 percent of the carbon-rich methanol solution flows back to a desulfurization section, 60.0 percent of the carbon-rich methanol solution is sent to a medium-pressure flash tower, wherein the pressure of the lower section of the medium-pressure flash tower is 0.5MPa, the pressure of the upper section of the medium-pressure flash tower is 1MPa, the temperature of the upper section of the medium-pressure flash tower is minus 40 ℃, the rest 0.6 percent of the carbon-rich methanol solution flows back to a pre-washing section, 11522.2kmol/H obtained at the top of a fine decarburization section tower contains 31.21 percent of CO2，2.69％CO2，0.48％N20.13% AR and a purge gas having a total sulfur content of less than 0.1 ppm. The sulfur-rich methanol and the carbon-rich methanol of T01 are respectively sent to T02 to flash off small amounts of CO and H in the methanol-rich solution2Then the mixture is sent to the bottom of T01 for reabsorption, 70 percent of carbon-rich methanol at the bottom of the upper section of the T02 tower is sent to the upper section of T03, the rest carbon-rich methanol and sulfur-rich methanol are sent to the lower section of the T03 tower, and the desorption is carried out to obtain 4018.7kmol/H, wherein the CO content is 0.68 percent, and the H content is 0.45 percent2，98.64％CO2，0.20％N2，0.01％CH3OH and less than 10ppmH2S is recycled gas. Wherein the temperature of the flash tank V01 is-25 ℃ and the pressure is 0.05 MPa. The upper tower bottom of T03 was branched to 10857.1kmol/h containing 6.97% CO2，0.13％H2O，92.89％CH3The semi-lean methanol of OH is fed into the top of T01 tower to be usedAbsorbent, lower column bottoms liquid sent to T04 for H2Concentrating S, and thermally regenerating in a methanol thermal regeneration tower to obtain 27142.9kmol/H containing 0.14% H2O，99.86％CH3OH-depleted methanol is sent to the top of T01 tower (the molar ratio of semi-lean solution to lean solution is 0.4:1), and H with content more than 25% is obtained at the top of the tower2The S gas is sent to the claus system.
Finally, compared to comparative example 1, CO2The recovery amount is increased by 65 percent, the consumption of poor methanol is reduced by 29 percent, and the absorption energy consumption is reduced by 5.8 percent.
Example 2
At 40 ℃, 3.08MPa, 17797.8kmol/H contains 20.35% of CO and 44.05% of H2，34.92％CO2，0.15％H2S，0.01％COS，0.31％N2，0.12％H2Raw material gas of O, 0.08% AR enters from the bottom of T01 tower to be desulfurized and decarbonized after heat exchange, and 43820.4kmol/H H of the bottom of fine decarbonization section tower2The molar content of S is 1X 10-624.8 percent of the carbon-rich methanol solution flows back to a desulfurization section, 75.0 percent of the carbon-rich methanol solution is sent to a medium-pressure flash tower, wherein the pressure of the lower section of the medium-pressure flash tower is 1MPa, the pressure of the upper section of the medium-pressure flash tower is 3MPa, the temperature of the medium-pressure flash tower is-20 ℃, the rest 0.2 percent of the carbon-rich methanol solution flows back to a pre-washing section, and 11648.6kmol/H containing 30.85 percent of CO and 67.19 percent of H is obtained at the top of2，1.35％CO2，0.48％N20.13% AR and a purge gas having a total sulfur content of less than 0.1 ppm. The sulfur-rich methanol and the carbon-rich methanol of T01 are respectively sent to T02 to flash off small amounts of CO and H in the methanol-rich solution2Then the mixture is sent to the bottom of T01 for reabsorption, 85 percent of carbon-rich methanol at the bottom of the upper section of the T02 tower is sent to the upper section of T03, the rest carbon-rich methanol and sulfur-rich methanol are sent to the lower section of the T03 tower, and the desorption is carried out to obtain 4486.9kmol/H, wherein the CO content is 0.47 percent, and the H content is 0.27 percent2，99.10％CO2，0.15％N2，0.01％CH3OH and less than 10ppmH2S is recycled gas. Wherein the temperature of the flash tank V01 is-50 ℃ and the pressure is 0.5 MPa. The bottom stream of the upper section of T03 tower contains 11.48% CO at 20727.3kmol/h2，0.11％H2O，88.41％CH3The semi-lean methanol of OH is fed into the top of T01 tower as absorbent, and the liquid at the bottom of the lower section is fed into T04 tower for H2S is concentrated and then fed into methanol for heatingThe crude column is thermally regenerated to obtain 17272.7kmol/H containing 0.15% H at the bottom of the column2O，99.85％CH3OH-depleted methanol is sent to the top of T01 tower (the molar ratio of semi-lean solution to lean solution is 1.2:1), and H with the content of more than 25% is obtained at the top of the tower2The S gas is sent to the claus system.
Finally, compared to comparative example 1, CO2The recovery amount is increased by 85 percent, the consumption of poor methanol is reduced by 53 percent, and the energy consumption of the absorption tower is reduced by 12.5 percent.
TABLE 1 comparison of enthalpy values of absorption towers in and out of the whole lean solution and the semi lean solution
Figure BDA0002972310840000061

Claims (5)

1. Semi-barren solution absorption and high CO2The low-temperature methanol washing process of yield is characterized in that the device involved in the process comprises an absorption tower (T01), a medium-pressure flash tower (T02), and CO2Desorber (T03), N2Stripper (T04) and methanol/CO2A flash tank (V01);
the absorption tower (T01) is divided into four sections, namely a prewashing section (1), a desulfurization section (2), a coarse decarburization section (3) and a fine decarburization section (4) from bottom to top, wherein the carbon-rich methanol (J1) in the absorption tower at the bottom of the coarse decarburization section (3) of the absorption tower is divided into three streams, one stream is sent to the prewashing section (1) of the absorption tower, the other stream is sent to the desulfurization section (2) of the absorption tower, and the last stream is sent to the upper section (6) of the medium-pressure flash tower; the sulfur-rich methanol (K) at the bottom of the desulfurization section (2) of the absorption tower is sent to the lower section of the medium-pressure flash tower;
the medium-pressure flash tower is divided into a lower section (5) of the medium-pressure flash tower and an upper section (6) of the medium-pressure flash tower from bottom to top, and sulfur-rich methanol at the bottom of the lower section (5) of the medium-pressure flash tower is sent to CO2The lower section of the desorption tower; the medium-pressure flash tower carbon-rich methanol (J2) at the bottom of the upper section (6) of the medium-pressure flash tower is divided into two parts, one part is sent to CO2The upper part of the desorber (T03) is fed with the other stream to CO2A lower section of a desorption tower (T03);
said CO2The desorption tower is divided into CO from bottom to top2The lower section (7) of the desorption tower and CO2Upper section of desorption tower(8) Two stages of, CO2Feeding the rich methanol at the bottom of the lower section (7) of the desorption tower into N2An upper section of a stripper column; CO22The semi-barren solution methanol at the bottom of the upper section (8) of the desorption tower is divided into two parts, one part of the semi-barren solution methanol (M) and the barren methanol (C) are sent to the top of the fine decarbonization section (4) of the absorption tower, and the other part is sent to N2An upper section of a stripper column (T04);
the methanol/CO2Flash tank (V01) is located in CO2Desorption column (T03) and N2Between the stripper columns (T04).
2. The process as claimed in claim 1, wherein the carbon-rich methanol with 0.2-0.6% molar content of the carbon-rich methanol (J1) in the absorption tower is refluxed to the pre-washing section of the absorption tower; the carbon-rich methanol accounting for 24.8 to 39.4 percent of the molar content of the carbon-rich methanol (J1) in the absorption tower flows back to the desulfurization section of the absorption tower, and the carbon-rich methanol accounting for 60.0 to 75.0 percent of the molar content of the carbon-rich methanol (J1) in the absorption tower enters the upper section of the medium-pressure flash tower; wherein H in the carbon-rich methanol2The molar content of S is 1X 10-7～1×10-6。
3. The process as claimed in claim 1, wherein the carbon-rich methanol (J2) is fed to the CO in an amount of 70 to 85 mol% based on the carbon-rich methanol (J2) in the medium-pressure flash column2The upper section (8) of the desorption tower, and the residual solution is fed into CO2The lower section (7) of the desorption tower absorbs sulfur in the gas; wherein the pressure range of the lower section (5) of the medium-pressure flash tower is 0.5MPa to 1MPa, the pressure range of the upper section (6) of the medium-pressure flash tower is 1MPa to 3MPa, and the temperature range is minus 40 ℃ to minus 20 ℃.
4. The process according to claim 1, characterized in that the molar ratio of semi-lean methanol (M) to lean methanol (C) is in the range of (0.4:1) to (1.2: 1); CO in semi-barren solution methanol2The molar content of (A) is 7.0-11.5%.
5. The process of claim 1, wherein the methanol/CO is methanol/CO2The pressure range of the flash tank (V01) is 0.05 MPa-0.5 MPa, and the temperature range is-50 ℃ to-25 ℃.
CN202110265939.0A 2021-03-11 2021-03-11 High CO2Recycled semi-barren solution circulation low-temperature methanol washing process Pending CN113019071A (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20120186296A1 (en) * 2009-06-12 2012-07-26 Nimalan Gnanendran Process and apparatus for sweetening and liquefying a gas stream
CN103468328A (en) * 2013-09-18 2013-12-25 中石化宁波工程有限公司 Novel low-temperature methanol washing process
CN106422672A (en) * 2016-10-26 2017-02-22 中石化宁波工程有限公司 Method for preventing low-temperature methanol washing heat regeneration system from being corroded
CN107297124A (en) * 2017-06-02 2017-10-27 西北大学 A kind of coproduction CO2Rectisol system and using its reclaim CO2Method
CN108310918A (en) * 2018-04-27 2018-07-24 北京石油化工工程有限公司 A kind of semi lean solution absorbs rectisol system and method

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20120186296A1 (en) * 2009-06-12 2012-07-26 Nimalan Gnanendran Process and apparatus for sweetening and liquefying a gas stream
CN103468328A (en) * 2013-09-18 2013-12-25 中石化宁波工程有限公司 Novel low-temperature methanol washing process
CN106422672A (en) * 2016-10-26 2017-02-22 中石化宁波工程有限公司 Method for preventing low-temperature methanol washing heat regeneration system from being corroded
CN107297124A (en) * 2017-06-02 2017-10-27 西北大学 A kind of coproduction CO2Rectisol system and using its reclaim CO2Method
CN108310918A (en) * 2018-04-27 2018-07-24 北京石油化工工程有限公司 A kind of semi lean solution absorbs rectisol system and method

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Application publication date: 20210625