Trapping method and trapping system for tar in coal gas

Abstract

The invention discloses a trapping method for tar in coal gas. The trapping method comprises steps as follows: gas-gas heat exchange: low-temperature gas exchanges heat with high-temperature coal gas, heat of the high-temperature gas is recovered, and the use amount of spray tar is reduced; trapping: low-temperature tar is sprayed on the high-temperature coal gas subjected to heat exchange, so that tar gas in the coal gas is condensed, separated out and recovered through trapping; defogging: tar fog drops about to escape are recovered gradually by use of a two-stage defogger. With the adoption of the tar trapping method, tar can be removed from the coal gas repeatedly, that is, the better tar recovery effect is realized in a tar washing manner. Compared with an existing technology for trapping tar through washing, firstly, the tar trapping method cannot produce a large amount of refractory wastewater, so that the investment, production and operation costs of wastewater treatment equipment are reduced; secondly, the trapping rate is high and secondary investment of an electrical tar precipitator is reduced. Besides, the invention further provides a trapping system for the tar in the coal gas.

Description

technical field [0001] The invention relates to the technical field of coal industry, in particular to a method and system for collecting tar in gas. Background technique [0002] Crude gas and raw pyrolysis gas (hereinafter collectively referred to as coal gas) produced during moving bed coal gasification and coal dry distillation pyrolysis usually contain a small amount of coal tar, and the tar in the gas needs to be recovered before entering the downstream process. [0003] At present, the recovery process of tar in gas usually adopts water washing method to wash, low temperature, oil-water separation of cooled oil-containing washing water to obtain coal tar, and regularly discharged washing wastewater is sent to sewage treatment plant after phenol and ammonia recovery. However, this tar recovery process often produces a large amount of refractory phenol and ammonia wastewater, resulting in high equipment investment and production and operation costs for wastewater treatm...

AI Technical Summary

Problems solved by technology

However, this tar recovery process often produces a large amount of refractory phenol and ammonia wastewater, resulting in high equipment investment and production and operation costs for wastewater treatment plants

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