Method for absorbing and separating light hydrocarbons from dry gas or industrial tail gas by utilizing ionic liquid

An ionic liquid and industrial tail gas technology, applied in separation methods, dispersed particle separation, petroleum industry, etc., can solve the problems of high energy consumption, difficult recycling, environmental and product pollution of cryogenic separation methods, and is suitable for industrialization. Production, favorable for mass transfer and diffusion, and the effect of less solvent consumption

Active Publication Date: 2015-01-14
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0010] Although the existing technology is relatively mature, the cryogenic separation method consumes a lot of energy and is generally suitable for the recovery of large-scale olefins, while the absorbent used in the absorption method is a molecular solvent, which has the disadvantages of being volatile and poor in thermal stability. Complete recycling and recycling, and easy to cause pollution to the environment and products

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0038] Absorbent composition: [P 4444 ][C 7 h 15 COO] Tetrabutylphosphonium n-octoate pure ionic liquid absorbent. Refinery dry gas composition (molar ratio): methane 23.0%, ethane 20.1%, ethylene 16.8%, propane 2.3%, propylene 5.2%, hydrogen 1.1%, nitrogen 22.4% and C 4 other components above.

[0039] The refinery dry gas is pressurized to 2.0MPa through the compressor, and the temperature is lowered to 10°C by cooling, and it is passed into the bottom of the absorption tower, and the absorbent is added to the top of the absorption tower to ensure that most of the C 2 ~C 4 Light hydrocarbons are absorbed, and the C-rich 2 ~C 4 The absorption liquid of light hydrocarbons, and insoluble nitrogen, hydrogen, methane and other residual tail gases are obtained from the top of the tower.

[0040] The absorption liquid at the bottom of the tower enters the desorption tower, adopts the method of temperature rise and desorption, the desorption temperature is controlled at 75°C,...

Embodiment 2

[0042] Absorbent composition: [N 4444 ][C 5 h 11 COO] Tetrabutylammonium n-hexanoate pure ionic liquid absorbent. Refinery dry gas composition: methane 24%, ethane 9.0%, ethylene 7.1%, propane 0.3%, propylene 1.2%, hydrogen 32%, air 19% and C 4 other components above.

[0043] As in Example 1, the dry gas and the absorbent are contacted and absorbed in countercurrent at 15°C and 2.0 MPa, and the absorbing liquid is desorbed at 70°C to produce C 2 ~C 4 Light hydrocarbons are recovered and recycled by the absorbent at the bottom of the tower. C 2 ~C 4 The comprehensive recovery rate of light hydrocarbons can reach 92.1%.

Embodiment 3

[0045] Absorbent composition: [bmpyrr][BuHPO 3 ]N,N-Butylmethylpyrrolidine phosphite butyl ionic liquid and C 6 For the mixed absorbent of hydrocarbons, the ionic liquid accounts for 80% (volume fraction). Dry gas composition: methane 19%, ethane 12.3%, ethylene 14.5%, propane 0.5%, propylene 1.3%, hydrogen 28%, air 18% and C 4 other components above.

[0046] As in Example 1, the dry gas and the absorbent are contacted and absorbed in countercurrent at 10°C and 3.5 MPa, and the absorbing liquid is heated and decompressed at 75°C and 0.2 MPa to desorb C 2 ~C 4 Light hydrocarbons are recovered and recycled by the absorbent at the bottom of the tower. C 2 ~C 4 The comprehensive recovery rate of light hydrocarbons can reach 96.3%.

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PUM

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Abstract

The invention discloses a method for absorbing and separating light hydrocarbons from dry gas or industrial tail gas by utilizing an ionic liquid. The ionic liquid or a mixed solvent of the ionic liquid and a molecular solvent is taken as an absorbent to be in contact with the dry gas or the industrial tail gas, an absorption liquid containing the light hydrocarbons is obtained by absorption and the light hydrocarbons are further obtained by desorption and separation; and the light hydrocarbons are alkanes or olefins which mainly contain C2-C4. The invention provides the method for absorbing and separating the light hydrocarbons from the dry gas or the industrial tail gas by utilizing the ionic liquid. The ionic liquid or the mixed solvent of the ionic liquid and the molecular solvent is taken as the absorbent, an absorption-desorption method is adopted for recovery and separation of the light hydrocarbons, and the absorbent has very high solubility of the light hydrocarbons and separation selectivity, so that efficient separation and recovery of the light hydrocarbons can be realized and the highest comprehensive recovery rate can achieve 98.5%.

Description

technical field [0001] The invention relates to the field of separation, recovery and purification of dry gas and industrial tail gas, in particular to a method for absorbing and separating light hydrocarbons from dry gas or industrial tail gas by using ionic liquid. Background technique [0002] Refinery dry gas produced by heavy oil catalytic cracking, thermal cracking, delayed coking, etc., as well as tail gas discharged from chemical equipment, etc., contain a certain amount of light hydrocarbon resources, but they are usually sent into the gas pipeline network as fuel gas, resulting in Low-grade utilization of resources. Therefore, the recovery of light hydrocarbons from dry gas and industrial tail gas has important practical and economic significance. [0003] At present, the industrial separation methods for hydrocarbon mixtures such as dry gas are mainly cryogenic separation method, solvent absorption method, absorption and rectification coupling separation method. ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C10G70/06C10G5/04B01D53/14
CPCB01D53/1412B01D53/1418C10G5/04C10G70/06C10G2300/10C10G2300/1003
Inventor 邢华斌赵旭杨启炜任其龙鲍宗必苏宝根张治国
Owner ZHEJIANG UNIV
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