Method for removing sulfide and light dydrocarbon from natural gas by utilizing ionic liquid

A technology of ionic liquid and natural gas, which is applied in the field of desulfurization and light hydrocarbon removal, can solve the problem of no separation effect of light hydrocarbon components, and achieve the effects of low saturated vapor pressure, high separation efficiency and good thermal stability

Active Publication Date: 2015-01-07
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This patent purifies natural gas with ethanol solution of conventional imidazole type ionic liquid, but this method can only remove

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0038] Absorbent composition: [P 4444 ][C 5 h 11 COO] Tetrabutylphosphonium n-hexanoate pure ionic liquid absorbent. Raw natural gas composition (molar ratio): methane 79.8%, ethane 1.9%, propane 7.6%, butane 5.6%, hydrogen sulfide 1.1%, sulfide 305mg / m 3 , Mercaptan 421mg / m 3 and other components.

[0039] The raw natural gas is pressurized to 1.0MPa through the compressor, and the temperature is lowered to 15°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 Hydrocarbons and organic sulfides are absorbed, and the C-rich 2 ~C 4 Absorption liquid of hydrocarbons and organic sulfides, methane-rich gas and a small amount of almost insoluble H in the absorbent are obtained at the top of the tower 2 , CO, N 2 Wait for gas.

[0040] The absorption liquid at the bottom of the tower enters the light hydrocarbon desorption tower, adopts the method of temper...

Embodiment 2

[0042] Absorbent composition: [N 4444 ][C 7 h 15 COO] tetrabutylammonium octanoate pure ionic liquid absorbent. Raw natural gas composition (molar ratio): 81.5% methane, 8.5% ethane, 8.5% propane, 5.1% butane, 1.0% hydrogen sulfide and other components.

[0043] As in Example 1, the raw natural gas and the absorbent are contacted and absorbed in countercurrent at 5°C and 2.5 MPa, and the light hydrocarbon components are desorbed by the absorption liquid at a temperature of 50°C. Hydrogen sulfide is desorbed at 0.1MPa, and the absorbent is recovered and recycled at the bottom of the tower. Hydrogen sulfide removal rate: 97.6%, ethane removal rate: 91.4%, propane removal rate: 95.2%, butane removal rate: 97.7%.

Embodiment 3

[0045] Absorbent composition: [bmpyrr][Bu 2 PO 4 ] N, N-butyl methylpyrrolidone phosphate dibutyl ionic liquid, N-methylpyrrolidone mixed absorbent, the ionic liquid accounts for 95% (volume fraction). Raw natural gas composition (molar ratio): methane 88.2%, ethane 5.9%, propane 2.0%, butane 0.9%, hydrogen sulfide 1.2% and other components.

[0046] As in Example 1, the raw natural gas and the absorbent are contacted and absorbed in countercurrent at 10°C and 1.8 MPa, and the light hydrocarbon components are desorbed by raising the temperature of the absorbing liquid at 55°C, and the absorbing liquid is then desorbed through a sulfide desorption tower at 85°C and 85°C. Hydrogen sulfide is desorbed at 0.05MPa, and the absorbent is recovered and recycled at the bottom of the tower. Hydrogen sulfide removal rate: 97.5%, ethane removal rate: 92.1%, propane removal rate: 96.7%, butane removal rate: 97.1%.

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Abstract

The invention discloses a method for removing sulfide and light dydrocarbon from natural gas by utilizing ionic liquid. The method comprises the following steps: taking the ionic liquid or a mixed solvent of the ionic liquid and a molecular solvent as an absorbent to contact with the natural gas and absorb the sulfide, the light dydrocarbon and the carbon dioxide in the natural gas so as to obtain absorption liquid and residual tail gas, wherein the light dydrocarbon is alkane or alkene containing C2-C4; and carrying out two-stage desorption on the absorption liquid so as to desorb the light dydrocarbon and the sulfide in sequence, wherein the absorbent obtained through the desorption is recycled. The method provided by the invention is used for removing the sulfide and the light dydrocarbon from the natural gas by taking the ionic liquid or the mixed solvent of the ionic liquid and the molecular solvent as the absorbent. The designed ionic liquid, the negative ion of which contains a long alkyl side chain, has high selective dissolving capacity for the gas such as hydrogen sulfide and light dydrocarbon and the selective dissolving capacity is superior to that of the conventional ionic liquid, so that the efficient removal of the sulfide and the recovery of the light dydrocarbon are realized.

Description

technical field [0001] The invention relates to the field of separation and purification of natural gas, in particular to a method for desulfurizing and delighting hydrocarbons from natural gas by using ionic liquid. Background technique [0002] As an important resource material, natural gas is also a particularly important basic raw material gas in the chemical industry. Due to the needs of some downstream processes and the recovery and utilization of resources, it is necessary to desulfurize natural gas and recover light hydrocarbons. At present, the absorption method is mostly used for desulfurization and light hydrocarbon removal in natural gas. [0003] The Chinese patent document with publication number CN101016492A discloses a low-temperature methanol washing process for decarbonization and desulfurization of natural gas raw material gas. Full contact, the hydrogen sulfide and carbon dioxide in the feed gas are absorbed by lean methanol, and the methanol-rich liqui...

Claims

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Application Information

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IPC IPC(8): C10L3/10B01D53/14
Inventor 赵旭邢华斌任其龙杨启炜苏宝根张治国鲍宗必苏云
Owner ZHEJIANG UNIV
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