CN114345084A - Device and method for absorbing methyl chloride in waste gas by ionic liquid at low temperature and variable pressure - Google Patents

Device and method for absorbing methyl chloride in waste gas by ionic liquid at low temperature and variable pressure Download PDF

Info

Publication number
CN114345084A
CN114345084A CN202210051753.XA CN202210051753A CN114345084A CN 114345084 A CN114345084 A CN 114345084A CN 202210051753 A CN202210051753 A CN 202210051753A CN 114345084 A CN114345084 A CN 114345084A
Authority
CN
China
Prior art keywords
gas
flash tank
ionic liquid
chloromethane
absorbent
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202210051753.XA
Other languages
Chinese (zh)
Inventor
雷志刚
李国选
刘清华
桂成敏
张傑
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Beijing University of Chemical Technology
Original Assignee
Beijing University of Chemical Technology
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Beijing University of Chemical Technology filed Critical Beijing University of Chemical Technology
Priority to CN202210051753.XA priority Critical patent/CN114345084A/en
Publication of CN114345084A publication Critical patent/CN114345084A/en
Pending legal-status Critical Current

Links

Images

Classifications

    • 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
    • B01D53/1487—Removing organic compounds
    • 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
    • B01D53/1493—Selection of liquid materials for use as 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
    • B01D53/18—Absorbing units; Liquid distributors therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2252/00—Absorbents, i.e. solvents and liquid materials for gas absorption
    • B01D2252/30—Ionic liquids and zwitter-ions
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2257/00—Components to be removed
    • B01D2257/20—Halogens or halogen compounds
    • B01D2257/206—Organic halogen compounds
    • B01D2257/2064—Chlorine

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

A device and a method for absorbing chloromethane in waste gas by ionic liquid at low temperature and variable pressure belong to the technical field of fine chemical separation and purification. The method comprises the steps of adopting an ionic liquid absorbent, enabling chloromethane-containing waste gas to enter a gas absorption tower (T1) from the bottom of the tower through a low-temperature pressure swing absorption method, enabling the absorbent to enter the gas absorption tower (T1) from the top of the tower, enabling the bottom material flow of the gas absorption tower (T1) to be connected with the middle of a first flash tank (S1), emptying air containing trace chloromethane at the top of the first flash tank (S1), enabling the absorbent rich in chloromethane gas to enter the middle of a second flash tank (S2) from the bottom of the first flash tank (S1), extracting the product chloromethane gas at the top of the second flash tank (S2), extracting the absorbent at the bottom of the second flash tank (S2), exchanging heat through a heat exchanger (H1), and conveying the absorbent to the top of the gas absorption tower (T1) through a conveying pump (P1). Has the characteristics of low energy consumption, short flow, low equipment cost, large absorption capacity, recyclable absorbent and the like.

Description

Device and method for absorbing methyl chloride in waste gas by ionic liquid at low temperature and variable pressure
Technical Field
The invention relates to a device and a method for absorbing methyl chloride in waste gas by ionic liquid at low temperature and variable pressure. The ionic liquid absorbent may be a single ionic liquid, a mixed ionic liquid, or a mixture of an ionic liquid and water. The invention belongs to the technical field of fine chemical engineering separation and purification.
Background
The unorganized emission of chlorine-containing waste gas generated in the industries of medicine, lithium battery diaphragms and the like threatens the life health of human bodies and the biological ecological environment. The traditional techniques such as activated carbon fiber adsorption have the problems of low adsorption capacity, inevitable secondary pollution, waste water discharge and the like. At present, in the production process of methyl chlorosilane and methane chloride, a large amount of chloromethane is contained in non-condensable gas of a condenser at the top of a separation tower, and if the gas is directly discharged, the atmosphere pollution is caused, the chloromethane gas cannot be recycled, and the resource waste is caused to a certain extent, so that the chloromethane tail gas needs to be recycled. At present, the chloromethane tail gas is treated by adopting an absorption tower to absorb the chloromethane tail gas and desorb and recover the chloromethane tail gas. However, the conventional absorbent (organic solvent) is volatile, which results in poor recovery effect and low recovery efficiency of methyl chloride tail gas, and is easy to cause secondary pollution. Furthermore, the organic solvent rich in methyl chloride requires a large amount of energy to be consumed in the desorption process. Therefore, the development of a novel green absorbent and an absorption device has important significance for recycling waste gas resources.
The ionic liquid is a salt consisting of organic cation and inorganic anion of nitrogen or phosphorus heterocycle, and is liquid at room temperature. The composite material has the advantages of high chemical stability, high thermodynamic stability, adjustable structure, difficult volatility, good conductivity and the like. The special structure and physical property characteristics bring wide development space for the application of the ionic liquid, and particularly the ionic liquid has good dissolving capacity on organic or inorganic compounds, so that the ionic liquid has great application potential in the aspect of treating gas pollution.
Chinese patent CN12717640A discloses an intelligent and efficient methyl chloride tail gas recovery device and a use method thereof, the system comprises an absorption tower, the change of methyl chloride tail gas circulation through a barrier disc can be realized through the overlapped area of a second gas hole groove and a first gas hole groove, the circulation of methyl chloride tail gas through the barrier disc becomes small, so that the time of methyl chloride tail gas remaining in the absorption tower is long, the sufficient reaction of the methyl chloride tail gas and absorption liquid is facilitated, the recovery effect of the methyl chloride tail gas is good, and the recovery efficiency is high.
Chinese patent CN112675667A discloses a system and a method for recovering and absorbing chloromethane in the production process of alkyl metal, which comprises a buffer tank, a vacuum pump, an elution tower, a solvent pump, a condenser, a recovery tank and a connecting pipeline, wherein the buffer tank is connected with the vacuum pump through the connecting pipeline, the vacuum pump is connected with the elution tower through the connecting pipeline, the elution tower is connected with the condenser through the connecting pipeline, the condenser is connected with the recovery tank through the connecting pipeline, and the upper end and the lower end of the elution tower are also connected with the solvent pump through the connecting pipeline. The invention solves the problems that the existing chloromethane absorption device is incomplete in absorption, cannot carry out integrated recovery operation, causes resource waste and greatly reduces the efficiency.
The literature (optimization analysis of the methyl chloride deep recovery process in the production of organic silicon, chemical management, volume 9 in 2020), discusses the optimization method of the methyl chloride recovery process in the production of organic silicon, and carries out different types of technical transformation on the basis of the existing process, including traditional condensation transformation, membrane separation transformation and absorption transformation. The technology reduces resource waste and production cost, but still has the problem of secondary pollution.
The invention realizes the high-efficiency separation of the waste gas containing the chloromethane (especially the waste gas which can be used in the production of the butyl rubber) by a low-temperature pressure swing absorption-flash evaporation method and adopting an absorbent based on the ionic liquid. The process has the characteristics of low energy consumption, short flow, low equipment cost, large absorption capacity, recyclable absorbent and the like, and is suitable for being popularized as a new technology for treating industrial chlorine-containing waste gas pollutants.
Disclosure of Invention
The invention aims to provide a device and a method for absorbing methyl chloride in waste gas by ionic liquid at low temperature and variable pressure. The method can reduce energy consumption and equipment cost in the process, shorten the process flow, and simultaneously has large absorption capacity for waste gas and recyclable absorbent.
The invention also aims to provide a device for absorbing methyl chloride by the method at low temperature and variable pressure.
It is another object of the present invention to provide the use of said method and apparatus to increase the separation efficiency of chloromethane containing waste gases and to increase the recovery of chloromethane products.
The invention is realized by the following technical scheme.
The device for absorbing methyl chloride in waste gas by ionic liquid at low temperature and variable pressure is characterized by mainly comprising the following parts:
a gas absorption tower (T1), a first flash tank (S1), a second flash tank (S2), a heat exchanger (H1) and a transfer pump (P1);
wherein the waste gas (G-CH) containing chloromethane3Cl) is connected with the lower part of a Gas absorption tower (T1) and enters a Gas absorption tower (T1), an ionic liquid absorbent (A1) is connected with the upper part of the Gas absorption tower (T1) and enters from the upper part, the bottom of the Gas absorption tower (T1) is connected with the middle part of a first flash tank (S1), an emptying pipe is arranged at the top of the first flash tank (S1) and is used for emptying Gas (Gas1) containing trace methyl chloride, the bottom of the first flash tank (S1) is connected with the middle part of a second flash tank (S2), so that an absorbent rich in methyl chloride Gas enters the middle part of the second flash tank (S2) from the bottom of the first flash tank (S1), a product methyl chloride Gas is extracted from the top of the second flash tank (S2), the absorbent is extracted from the bottom of the second flash tank (S2) and passes through a heat exchanger (H1), a transfer pump (P1) is connected with the upper part of the Gas absorption tower (T1), so that the absorbent is extracted from the bottom of the second flash tank (S2) and exchanges heat with the heat exchanger (S638), and then is conveyed back to the gas absorption tower (T1) by a conveying pump (P1) for recycling.
The pressure of the second flash tank (S2) is less than the pressure of the first flash tank (S1).
It is preferable that the pressure of the gas absorption column (T1) is not less than the pressure of the first flash tank (S1).
The first flash tank (S1) is mainly used to equalize the buffer pressure while releasing a small amount of Gas (Gas-2) at the top, which contains a small amount of methyl chloride.
The method for absorbing methyl chloride in waste gas by adopting the device and based on the ionic liquid absorbent under the condition of low temperature and pressure swing mainly comprises the following steps:
(1) chlorine-containing methane waste gas (G-CH)3Cl) enters the gas absorption tower (T1) from the lower part, the ionic liquid absorbent (A1) enters the gas absorption tower (T1) from the upper part of the tower, and the gas enters the gas absorption tower (T1)The bottom stream of the absorption tower (T1) is connected with the middle part of a first steaming tank (S1) for further separation;
(2) the gas containing trace chloromethane is emptied at the top of the first flash tank (S1), and the absorbent of the chloromethane-rich gas enters the middle part of the second flash tank (S2) from the bottom of the first flash tank (S1);
(3) the product chloromethane gas is extracted from the top of the second flash tank (S2), and the ionic liquid absorbent is extracted from the bottom of the second flash tank (S2);
(4) and the ionic liquid absorbent extracted from the bottom of the second flash tank (S2) is subjected to heat exchange through a heat exchanger (H1), and then is conveyed back to the top of the gas absorption tower (T1) by a conveying pump (P1) to be connected with the upper part of the gas absorption tower (T1) for recycling of the ionic liquid absorbent.
According to another preferred embodiment of the invention, the cation of the ionic liquid is one or more of imidazole, pyridine, amino and the like, and the anion is one or more of halide salt, F-containing acid, O-containing acid, halide and the like. The absorbent is single ionic liquid, mixed ionic liquid or a mixture of the ionic liquid and water.
The mass ratio of the total amount of the absorbent to the chloromethane-containing gas is 1-8: 1.
According to another preferred embodiment of the present invention, the gas absorption column (T1) is operated at a pressure of 0.5 to 10atm, preferably not less than 1atm, at an operating temperature of 20 to 100 ℃, with a theoretical plate number N of 3 to 15, preferably 5 to 10, and the chloromethane-containing off-gas is fed at the (N-1) th to N-th positions in the gas absorption column (T1) and at the absorbent feeding positions of 1 to 2 th positions.
According to another preferred embodiment of the present invention, the operating pressure of the first flash tank (S1) is 0.5 to 1atm, preferably 1atm, the flash temperature is 20 to 100 ℃, the operating pressure of the second flash tank (S2) is 0.01 to 0.8atm, the flash temperature is 20 to 140 ℃, and the operating pressure of the second flash tank (S2) is guaranteed to be lower than the operating pressure of the first flash tank (S1).
According to another preferred embodiment of the invention, the waste gas of the invention is especially waste gas in butyl rubber production, the content of the chloromethane and dimethyl ether in the waste gas is 0-50 wt%, the technology of the invention can separate chloromethane and dimethyl ether and achieve the purity of recycling, when the mass content of chloromethane in the waste gas is 5-40%, the content of chloromethane in the purified gas is less than 400ppm, and the recovery rate of chloromethane is 98.50-99.90%.
When the waste Gas of the invention is the waste Gas in the production process of butyl rubber, the dimethyl ether is basically discharged from the top of the first flash tank (S1), namely the dimethyl ether is discharged from the Gas (Gas1) containing trace methyl chloride, and the methyl chloride discharged from the top of the second flash tank does not contain dimethyl ether.
According to another preferred embodiment of the present invention, the low temperature means that the maximum temperature during the absorption-desorption operation is lower than 100 ℃, which is lower than the desorption operation temperature of the conventional absorption process, thereby saving the energy consumption of the process.
Compared with the prior art, the invention mainly has the following beneficial effects:
(1) the method has the advantages of simple process and convenient operation, successfully separates the waste gas containing the chloromethane, and improves the resource utilization rate of the chloromethane.
(2) The method adopts the absorbent based on the ionic liquid, strengthens the separation effect of the absorption process, has simple recovery process of the absorbent, reduces the energy consumption of the process and further reduces the cost of the process.
Drawings
FIG. 1 is a process flow diagram of a device and a method for absorbing methyl chloride in waste gas by ionic liquid at low temperature and variable pressure.
In the figure, T1-gas absorption column; s1-a first flash tank; s2-a second flash tank; h1-heat exchanger; p1-delivery pump.
G-CH3Cl-chloromethane-containing waste gas; a 1-ionic liquid absorbent; gas 1-Gas containing trace amounts of methyl chloride, a small amount of Gas being released at the top of the Gas-2 first flash tank (S1); CH3 Cl-methyl chloride gas.
Detailed Description
The present invention will be further described with reference to examples, but the present invention is not limited to the following examples, and various examples are included in the technical scope of the present invention without departing from the spirit of the invention described above.
Example 1:
using a single ionic liquid (taking [ EMIM ] [ Ac ] as an example)
The feed flow of the waste gas containing the chloromethane is 100kg/h, 5 percent (mass fraction) of chloromethane, 1 percent (mass fraction) of water and 0.1 percent (mass fraction) of dimethyl ether are contained in the feed, and the balance is nitrogen. The theoretical plate number of the gas absorption tower (T1) is 8, the feeding position of the waste gas containing the chloromethane is 8, the single ionic liquid (taking [ EMIM ] [ Ac ] as an example) is fed from the position of the 1 st plate of the gas absorption tower (T1), the operating pressure and the temperature of the gas absorption tower (T1) are 2.2atm and 30 ℃, respectively, the feeding mass ratio of the ionic liquid and the waste gas containing the chloromethane in the absorption process is 2:1, the flash evaporation temperature of the first flash tank (S1) is 40 ℃, the operating pressure is 1atm, the flash evaporation temperature of the second flash tank (S2) is 40 ℃, the operating pressure is 0.02atm, the content of the chloromethane in the purified gas at the top of the gas absorption tower (T1) is lower than 390ppm, the recovery rate of the chloromethane is 99.6 percent, and the dimethyl ether in the gas at the top of the second flash tank (S2). The purity of the recycled ionic liquid is 99.99 percent (mass fraction).
Example 2:
adopts mixed ionic liquid (taking [ EMIM ] [ Ac ] 50% + [ EMIM ] [ BF4] 50% as an example)
The feed flow of the waste gas containing the chloromethane is 100kg/h, the feed contains 8 percent (mass fraction) of chloromethane, 1 percent (mass fraction) of water, 0.1 percent (mass fraction) of dimethyl ether, and the balance of nitrogen. The theoretical plate number of the gas absorption tower (T1) is 10, the feeding position of the waste gas containing chloromethane is 10, the mixed ionic liquid (for example, [ EMIM ] [ Ac ] 50% + [ EMIM ] [ BF4] 50%) is fed from the position of the 1 st plate of the gas absorption tower (T1), the operating pressure and temperature of the gas absorption tower (T1) are 2.5atm and 30 ℃, the feeding mass ratio of the ionic liquid to the waste gas containing chloromethane during absorption is 2:1, the flash temperature of the first flash tank (S1) is 50 ℃, the operating pressure is 1atm, the flash temperature of the second flash tank (S2) is 40 ℃, the operating pressure is 0.03atm, the content of chloromethane in the purified gas at the top of the gas absorption tower (T1) is lower than 320ppm, the recovery rate of chloromethane is 99.85%, and the gas at the top of the second flash tank (S2) does not contain dimethyl ether. The purity of the recycled ionic liquid is 99.99 percent (mass fraction).
Example 3:
using a mixture of ionic liquid and water (for example, [ EMIM ] [ Ac ] 90% + Water 10%)
The feed flow of the waste gas containing the chloromethane is 100kg/h, the feed contains 6 percent (mass fraction) of chloromethane, 1 percent (mass fraction) of water, 0.1 percent (mass fraction) of dimethyl ether, and the balance of nitrogen. The theoretical plate number of the gas absorption tower (T1) is 9, the feeding position of the waste gas containing chloromethane is 9, the operating pressure and temperature of the gas absorption tower (T1) are 2atm and 30 ℃, respectively, the ionic liquid and water mixture (taking [ EMIM ] [ Ac ] 90% + water 10% as an example) is fed from the position of the 1 st plate of the gas absorption tower (T1), the feeding mass ratio of the ionic liquid to the waste gas containing chloromethane in the absorption process is 3:1, the flash temperature of the first flash tank (S1) is 40 ℃, the operating pressure is 1atm, the flash temperature of the second flash tank (S2) is 50 ℃, the operating pressure is 0.03atm, the content of chloromethane in the purified gas at the top of the gas absorption tower (T1) is lower than 350ppm, the recovery rate of the chloromethane is 99.75%, and the gas at the top of the second flash tank (S2) does not contain dimethyl ether. The purity of the recycled ionic liquid is 99.99 percent (mass fraction).
Example 4:
adopts single ionic liquid (taking BMIM ] [ PF6] as an example)
The feed flow of the waste gas containing the chloromethane is 100kg/h, 5 percent (mass fraction) of chloromethane, 1 percent (mass fraction) of water and 0.1 percent (mass fraction) of dimethyl ether are contained in the feed, and the balance is nitrogen. The theoretical plate number of the gas absorption tower (T1) is 8, the feeding position of the waste gas containing chloromethane is 8, the single ionic liquid (taking BMIM ] [ PF6] as an example) is fed from the position of the 1 st plate of the gas absorption tower (T1), the operating pressure and temperature of the gas absorption tower (T1) are 2.5atm and 35 ℃, the feeding mass ratio of the ionic liquid and the waste gas containing chloromethane in the absorption process is 2:1, the flash evaporation temperature of the first flash tank (S1) is 40 ℃, the operating pressure is 1atm, the flash evaporation temperature of the second flash tank (S2) is 40 ℃, the operating pressure is 0.01atm, the content of chloromethane in the purified gas at the top of the gas absorption tower (T1) is lower than 360ppm, the recovery rate of the chloromethane is 99.5%, and the gas at the top of the second flash tank (S2) does not contain dimethyl ether. The purity of the recycled ionic liquid is 99.99 percent (mass fraction).
Example 5:
adopts mixed ionic liquid (taking BMIM ] [ BF4] 50% + [ BMIM ] [ PF6] 50% as an example)
The feed flow of the waste gas containing the chloromethane is 100kg/h, 5 percent (mass fraction) of chloromethane, 1 percent (mass fraction) of water and 0.1 percent (mass fraction) of dimethyl ether are contained in the feed, and the balance is nitrogen. The theoretical plate number of the gas absorption tower (T1) is 8, the feeding position of the waste gas containing chloromethane is 8, the mixed ionic liquid (for example, [ BMIM ] [ BF4] 50% + [ BMIM ] [ PF6] 50%) is fed from the position of the 1 st plate of the gas absorption tower (T1), the operating pressure and temperature of the gas absorption tower (T1) are 2.2atm and 25 ℃, respectively, the feeding mass ratio of the ionic liquid to the waste gas containing chloromethane during absorption is 2:1, the flash temperature of the first flash tank (S1) is 40 ℃, the operating pressure is 1atm, the flash temperature of the second flash tank (S2) is 50 ℃, the operating pressure is 0.01atm, the content of chloromethane in the purified gas at the top of the gas absorption tower (T1) is lower than 295ppm, the recovery rate of chloromethane is 99.55%, and the gas at the top of the second flash tank (S2) does not contain dimethyl ether. The purity of the recycled ionic liquid is 99.99 percent (mass fraction).
Example 6:
mixing the ionic liquid with water (for example, [ EMIM ] [ Ac ] 45% + [ EMIM ] [ BF4] 45% + water 10%)
The feed flow of the waste gas containing the chloromethane is 100kg/h, the feed contains 8 percent (mass fraction) of chloromethane, 1 percent (mass fraction) of water, 0.1 percent (mass fraction) of dimethyl ether, and the balance of nitrogen. The theoretical plate number of the gas absorption tower (T1) is 10, the feeding position of the waste gas containing chloromethane is 10, the water-containing mixed ionic liquid and (taking [ EMIM ] [ Ac ] 45% + [ EMIM ] [ BF4] 45% + water 10% as an example) are fed from the position of the 1 st plate of the gas absorption tower (T1), the operating pressure and temperature of the gas absorption tower (T1) are 2.8atm and 30 ℃ respectively, the feeding mass ratio of the ionic liquid to the waste gas containing chloromethane during absorption is 2:1, the flash evaporation temperature of the first flash evaporation tank (S1) is 50 ℃, the operating pressure is 1atm, the flash evaporation temperature of the second flash evaporation tank (S2) is 50 ℃, the operating pressure is 0.01atm, the content of chloromethane in the purified gas at the top of the gas absorption tower (T1) is lower than 260ppm, the recovery rate of the chloromethane is 99.8%, and the gas at the top of the second flash evaporation tank (S2) does not contain dimethyl ether. The purity of the recycled ionic liquid is 99.99 percent (mass fraction).
The data show that the product separated by the method has high purity and high recovery rate, the resource utilization rate of the waste gas containing the chloromethane is greatly improved, and the obtained high-purity chloromethane product can be used for downstream production.

Claims (10)

1. The device for absorbing methyl chloride in waste gas by ionic liquid at low temperature and variable pressure is characterized by mainly comprising the following parts:
a gas absorption tower (T1), a first flash tank (S1), a second flash tank (S2), a heat exchanger (H1) and a transfer pump (P1);
wherein the waste gas (G-CH) containing chloromethane3Cl) is connected with the lower part of a Gas absorption tower (T1) and enters a Gas absorption tower (T1), an ionic liquid absorbent (A1) is connected with the upper part of the Gas absorption tower (T1) and enters from the upper part, the bottom of the Gas absorption tower (T1) is connected with the middle part of a first flash tank (S1), an emptying pipe is arranged at the top of the first flash tank (S1) and is used for emptying Gas (Gas1) containing trace methyl chloride, the bottom of the first flash tank (S1) is connected with the middle part of a second flash tank (S2), so that an absorbent rich in methyl chloride Gas enters the middle part of the second flash tank (S2) from the bottom of the first flash tank (S1), a product methyl chloride Gas is extracted from the top of the second flash tank (S2), the absorbent is extracted from the bottom of the second flash tank (S2) and passes through a heat exchanger (H1), a transfer pump (P1) is connected with the upper part of the Gas absorption tower (T1), so that the absorbent is extracted from the bottom of the second flash tank (S2) and exchanges heat with the heat exchanger (S638), and then is conveyed back to the gas absorption tower (T1) by a conveying pump (P1) for recycling.
2. The apparatus for the low-temperature pressure swing absorption of methyl chloride in an off-gas with an ionic liquid according to claim 1, wherein the first flash tank (S1) is mainly used for buffering the equilibrium pressure.
3. The apparatus for the low-temperature pressure swing absorption of methyl chloride in an off-gas with an ionic liquid according to claim 1, wherein the pressure of the second flash tank (S2) is lower than the pressure of the first flash tank (S1).
4. The apparatus for the low-temperature pressure swing absorption of methyl chloride in an off-gas with an ionic liquid according to claim 1, wherein the pressure of the gas absorption tower (T1) is not less than the pressure of the first flash tank (S1).
5. The method for carrying out low-temperature pressure swing absorption of methyl chloride in waste gas based on the ionic liquid absorbent by adopting the device of claim 1 is characterized by mainly comprising the following steps:
(1) chlorine-containing methane waste gas (G-CH)3Cl) enters a gas absorption tower (T1) from the lower part, an ionic liquid absorbent (A1) enters the gas absorption tower (T1) from the upper part of the tower, and the bottom stream of the gas absorption tower (T1) is connected with the middle part of a first distillation tank (S1) for further separation;
(2) the gas containing trace chloromethane is emptied at the top of the first flash tank (S1), and the absorbent of the chloromethane-rich gas enters the middle part of the second flash tank (S2) from the bottom of the first flash tank (S1);
(3) the product chloromethane gas is extracted from the top of the second flash tank (S2), and the ionic liquid absorbent is extracted from the bottom of the second flash tank (S2);
(4) and the ionic liquid absorbent extracted from the bottom of the second flash tank (S2) is subjected to heat exchange through a heat exchanger (H1), and then is conveyed back to the top of the gas absorption tower (T1) by a conveying pump (P1) to be connected with the upper part of the gas absorption tower (T1) for recycling of the ionic liquid absorbent.
6. The method according to claim 5, wherein the cation of the ionic liquid is one or more of imidazole, pyridine, amino and the like, and the anion is one or more of halide salt, F-containing acid, O-containing acid, halide and the like; the absorbent is single ionic liquid, mixed ionic liquid or a mixture of the ionic liquid and water.
7. The method according to claim 5, wherein the mass ratio of the total amount of the absorbent to the chloromethane-containing gas is 1 to 8: 1.
8. The process according to claim 5, wherein the gas absorption column (T1) is operated at a pressure of 0.5 to 10atm, preferably not less than 1atm, at an operating temperature of 20 to 100 ℃, with a theoretical plate number N of 3 to 15, preferably 5 to 10, and the chloromethane-containing off-gas is fed to the gas absorption column (T1) at a position (N-1) to N and at a position (1) to 2) as absorbent;
the operating pressure of the first flash tank (S1) is 0.5-1 atm, preferably 1atm, the flash temperature is 20-100 ℃, the operating pressure of the second flash tank (S2) is 0.01-0.8 atm, the flash temperature is 20-140 ℃, and the operating pressure of the second flash tank (S2) is lower than the operating pressure of the first flash tank (S1).
9. The method according to claim 5, characterized in that the waste gas is especially the waste gas in the production of butyl rubber, and the content of the chloromethane gas in the waste gas is 0-50 wt%; when the mass content of the methyl chloride in the waste gas is 5-40%, the content of the methyl chloride in the purified gas is lower than 400ppm, and the recovery rate of the methyl chloride is 98.50-99.90%.
10. The process according to claim 5, wherein when the off-Gas is an off-Gas from a process for producing butyl rubber, dimethyl ether is substantially discharged from the top of the first flash tank (S1) and is contained in the Gas (Gas1) containing a trace amount of methyl chloride, and dimethyl ether is not contained in the methyl chloride discharged from the top of the second flash tank.
CN202210051753.XA 2022-01-17 2022-01-17 Device and method for absorbing methyl chloride in waste gas by ionic liquid at low temperature and variable pressure Pending CN114345084A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202210051753.XA CN114345084A (en) 2022-01-17 2022-01-17 Device and method for absorbing methyl chloride in waste gas by ionic liquid at low temperature and variable pressure

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202210051753.XA CN114345084A (en) 2022-01-17 2022-01-17 Device and method for absorbing methyl chloride in waste gas by ionic liquid at low temperature and variable pressure

Publications (1)

Publication Number Publication Date
CN114345084A true CN114345084A (en) 2022-04-15

Family

ID=81091665

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202210051753.XA Pending CN114345084A (en) 2022-01-17 2022-01-17 Device and method for absorbing methyl chloride in waste gas by ionic liquid at low temperature and variable pressure

Country Status (1)

Country Link
CN (1) CN114345084A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117717878A (en) * 2024-01-31 2024-03-19 成都理工大学 Ionic liquid and method for efficiently absorbing toluene waste gas at normal pressure

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117717878A (en) * 2024-01-31 2024-03-19 成都理工大学 Ionic liquid and method for efficiently absorbing toluene waste gas at normal pressure

Similar Documents

Publication Publication Date Title
CN109126392B (en) Method for carrying out CO (carbon monoxide) in flue gas by adopting ionic liquid2Trapping device and process
CN102502498B (en) Method for separating and recovering chlorine and oxygen of hydrogen chloride oxidation gas mixture by use of PSA (Pressure Swing Adsorption) technology
CN112387071A (en) CO2Trapping method and apparatus
CN101337861B (en) Method for purifying and recovering methyl chloride of glyphosate byproduct
CN102101651A (en) Method and device for refining chlorine hydride byproduct and recovering trifluoromethane in production of monochlorodifluoromethane
CN105693452A (en) Purifying system and method for acetylene preparation from natural gas
CN107158888A (en) A kind of phase transformation traps SO2Absorbing liquid
CN108159842B (en) Method for reducing VOC content in tail gas generated by methane chloride device
CN105820846B (en) A kind of full temperature journey pressure swing adsorption purge method of coke-stove gas benzene-removal naphthalene-removal
CN1935319B (en) Oil gas adsorption recovering method and apparatus utilizing heating desorption
CN108404612A (en) A kind of rich solution multi-stage heat exchanger type carbon dioxide capture system and technique
CN110756003A (en) Method for separating tetrahydrofuran in waste gas by adopting membrane absorption treatment
CN114345084A (en) Device and method for absorbing methyl chloride in waste gas by ionic liquid at low temperature and variable pressure
CN107778124A (en) A kind of oil refinery dry gas recovery H2 and C2+ full temperature journey sorption extraction partition method
CN101890284A (en) Method and device for obtaining CO2 from discharged gas fume
CN215609428U (en) Device for purifying propane and propylene
CN113786711A (en) Method for recovering chlorine-containing volatile organic compounds in organic waste gas by using ionic liquid
CN100491245C (en) Method for preparing liquid carbon dioxide in foodstuff level by using tail gas of cement kiln
CN105214450B (en) A kind of selective absorbing SO2Absorbent and absorb SO2Process
CN109319736A (en) Ammonia tank periodic off-gases recyclable device and its technique
CN211585925U (en) Absorption system suitable for phase change absorbent absorbs CO2 in flue gas
CN217473105U (en) Device for absorbing methyl chloride in waste gas by ionic liquid at low temperature and variable pressure
CN104043316B (en) A kind of collecting carbonic anhydride of being coupled with low temperature multiple-effect distillation technology or piece-rate system
CN103113947A (en) Methane separation and purification device and method thereof for purifying methane by absorbing CO2 through alkaline method
CN107198967A (en) Multiple-effect membrane regeneration plant and method for gas purification solvent reclamation

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination