Coking tail gas treatment method

Abstract

The invention relates to a coked tail gas processing method. The method is characterized by including the following steps of cooling coked tail gas, separating out the liquid phase, transmitting obtained noncondensable gas to an absorption tower lower tower together with circulation methyl alcohol through a liquid-gas jet pump, discharging the mixture out of methyl alcohol at the bottom of the tower through bubbling, making the mixture make countercurrent contact with washing methyl alcohol entering the upper portion of the absorption tower lower tower between all layers of tower plates, washing and absorbing harmful substances, sending the rest of noncondensable gas to a methyl alcohol washing tower upper tower, further removing residual low-condensation organic hydrocarbon and benzene series, conducting emptying, heating and pressurizing on rich methyl alcohol coming out of a tower kettle at the bottom of the absorption tower lower tower, dividing rich methyl alcohol into two parts, sending one part to a biochemical device to metabolize and convert sulfur-containing harmful substances in rich methyl alcohol, dividing the other part of rich methyl alcohol into two streams, using the first stream as a pumping power source of the liquid-gas jet pump, cooling the second stream, mixing the second stream with fresh deficient methyl alcohol, and using the mixture as washing methyl alcohol to be sent to the absorption tower lower tower.

Description

technical field [0001] The invention relates to a method for treating a chemical tail gas, in particular to a method for treating a coking tail gas containing a large amount of water vapor, hydrocarbons and sulfides volatilized in the delayed coking cooling and cutting water of an oil refinery. Background technique [0002] Coking is one of the important processing methods for residual oil. The decoking technology of delayed coking in my country has reached the international advanced level, and hydraulic decoking is widely used. A large amount of cold coke water with a temperature of about 100 ℃, a large amount of coking tail gas volatilized during the high temperature reuse treatment process of these sewage, the generation of coking tail gas is directly related to the cold cut coke water treatment process adopted by the enterprise, domestic and foreign There are three kinds of treatment processes for cold-cut coke water: open treatment process, semi-open treatment process and...

AI Technical Summary

Problems solved by technology

The main problem of this method is that on the one hand, the absorbent needs to be pre-cooled, and it is operated under normal pressure. The absorption efficiency of low-temperature diesel oil itself is not high, the consumption of absorbent is large, and the cooling energy consumption is large. Moreover, the components in the coking tail gas are large. Part of it is water vapor, so that the rich liquid returned to the hydrogenation unit carries a large amount of water. In addition, the lye is used as the absorption solvent, there is regular consumption of lye and the waste lye usually contains 3% to 10% of free alkali, sodium sulfide and Sodium mercaptide ranges from thousands to tens of thousands of mg / m 3 between, recovery and regeneration are difficult, costly, and easily cause secondary pollution

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