Alkaline desulfurization method and device for liquefied petroleum gas

Abstract

The invention provides an alkali lye desulfurization method and device of liquefied petroleum gas, the alkali lye desulfurization method is as follows: mixing alkali lye with hydrocarbon oil and a deoxidizing agent, separating oil phase, contacting with the liquefied petroleum gas for alkali lye desulfurization reaction, and collecting the liquefied petroleum gas product. The alkali lye desulfurization method and device can avoid or reduce the generation of disulfides and polysulfides, and significantly improves the desulfurization efficiency of the alkali lye desulfurization process, and after desulfurization, the sulfur content in the liquefied petroleum gas is dramatically reduced.

Description

technical field [0001] The invention relates to a method for desulfurizing liquefied petroleum gas, in particular to a method for desulfurizing lye in liquefied petroleum gas. Background technique [0002] As we all know, MTBE (methyl tert-butyl ether) is the largest non-hydrocarbon high-octane blending component in gasoline in my country, which can significantly improve gasoline quality. However, under the current production conditions, the output MTBE obviously contains sulfides, generally the sulfur content reaches 60-300 mg / kg, and the sulfur content of MTBE produced by some manufacturers is sometimes as high as 2000 mg / kg. [0003] MTBE can be synthesized from isobutene and methanol under acidic conditions, and the industry directly uses liquefied petroleum gas containing isobutene as a raw material, which greatly reduces the production cost of MTBE. However, the international standard for the sulfur content of civil liquefied petroleum gas has not changed over the yea...

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Problems solved by technology

The disadvantage of this process is that the energy consumption of re-distillation is high, and the second is that the boiling point of sulfide in C4 is not much different from that of light C4 such as isobutylene, so it is difficult to separate completely, and the sulfur content of the obtained MTBE is also difficult to remove to 10mg. / kg or less

However, in fact, the use of peroxides as oxidants or sources of oxygen in liquefied petroleum gas production plants has great potential safety hazards, and the mercaptans in liquefied petroleum gas are oxidized to disulfides and then distilled again. All the petroleum gas is gasified again. It is necessary to ensure the complete separation of the disulfides at the bottom of the tower. The energy consumption of the operation is very high, and there is also the problem that the disulfides or polysulfides are partially decomposed and then enter the evaporated liquefied petroleum gas again.

[0012] The existing liquefied petroleum gas desulfurization process has encountered a bottleneck: after the sulfur content is reduced to a certain level, no matter how much the cost is, the sulfur content will no longer be reduced or the improvement will be small, but it consumes doubled resources in vain: adding more devices, Use multiple additives, consume a large amount of lye and amine solution, and significantly increase the environmental protection treatment pressure of alkaline sewage

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