Combination method for deep desulfurization of liquefied gas

Abstract

The invention relates to a combination method for deep desulfurization of liquefied gas. The method comprises the steps that liquefied gas is fed into an extraction tower to contact with an alkali liquor counter flow, desulfurized liquefied gas and regenerated alkali liquor are fed into a static mixer to be mixed and then the obtained mixture is subjected to secondary extraction, mixed liquid is separated in a liquefied gas-alkali liquor separation tank, liquid gas is fed to be subjected to water washing, alkali liquor to be generated flowing out of the bottom of the extraction tower enters a flash tank, residual liquefied gas discharged from the top of the tank is conveyed to a gas system, alkali liquor to be generated obtained at the bottom of the tank, after being heated, enters a high gravity reactor to react with non-purified air, tail gas discharged from the high gravity reactor, after being subjected to alkali liquor removal by a coalescer, is fed back to the flash tank, the tail gas subjected to alkali liquor removal is fed into a diesel oil absorption tower to contact with a diesel oil counter flow, purified tail gas discharged from the top of the tower returns to the high gravity reactor to be recycled, rich diesel oil discharged from the bottom of the tower is conveyed to a diesel oil hydrogenation device, and the obtained regenerated alkali liquor is recycled. According to the method, the desulphurization depth is large, the regenerated alkali liquor quality is high, the equipment is simple and reliable, the cost is low, the emission amount of 'three wastes' is few, and the whole process conforms to the requirements of environmental protection.

Description

technical field [0001] The invention relates to a liquefied gas desulfurization process, in particular to a combined process for removing sulfur-containing components in liquefied gas by using lye, realizing regeneration of lye and reducing pollutant discharge. Background technique [0002] With the acceleration of the formulation and promotion of National V gasoline standards, the contradiction between the reduction of sulfur content in hydrogenated gasoline and insufficient octane number has gradually emerged. MTBE is a high-octane gasoline additive component. The sulfur content of the 19 refinery-type MTBE units of PetroChina is generally 100-400ppm, which is difficult to meet the National V gasoline standard (sulfur content is less than 10μg / g). The study found that the main reason for the excessive sulfur content of MTBE is the accumulation of carbon four sulfides in the raw material mixture, and these sulfides come from the regeneration unit of liquefied gas alkali elu...

AI Technical Summary

Problems solved by technology

[0003] (1) The oxidation in the regenerative oxidation tower is not complete, and the oxygen utilization rate is generally only 10-15%. Most of the oxygen only plays the role of fully mixing the gas and liquid and blowing off the disulfide, resulting in insufficient oxidation, and the sodium mercaptide has no Complete conversion to disulfide, a large amount of unoxidized sodium mercaptide in the regenerated lye inhibits the reaction between mercaptan and sodium hydroxide in the liquefied gas, resulting in a decrease in extraction capacity;

[0004] (2) Part of the disulfides produced by oxidation exist in the regenerated lye in the state of microemulsion. The separation of disulfide and lye is not complete, and the settling time of some devices is not enough to cause poor separation effect. high substance content;

The existing technology has taken a solution to this problem, but the control effect is not ideal, the sulfur content of the circulating lye is high, the lye consumption is large, the desulfurization depth of the liquefied gas is not enough, and disulfide is easy to produce secondary pollution

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