Method for recycling methyl chloride tail gas in chemical production process

Abstract

The invention discloses a method for recycling methyl chloride tail gas in the chemical production process. The method comprises the steps that noncondensable gas which contains chloromethane and is discharged from a condenser of a separation tower enters the bottom of an absorption tower, and an absorbent methyl alcohol or methane chloride is injected from the top of the absorption tower, chloromethane gas in the noncondensable gas is absorbed, the gas coming out of the top of the absorption tower recycles the absorbent through the condenser, then tail gas is sent to a rear system, absorptionliquid which is rich in absorbent and comes out of the bottom of the absorption tower is sent to other devices for reuse. Accordingly, the difference of the volatility of all ingredients in noncondensable gas and the excellent selective absorption of the absorbent on the chloromethane gas under different temperature and pressure conditions are fully utilized, thechloromethane gas inthechloromethane tail gas can be fully recycled, the chloromethane recovery rate is larger than or equal to 95 wt%, the content of chloromethane in tail gas obtained after absorption is smaller than or equal to 0.1wt%, and the loss of the absorbent is smaller than or equal to 0.5 wt%, not only are valuable materials recycled to the greatest extent, but also energy consumption is low; meanwhile, the processingpressure of the rear system and environmental pollution are reduced, and the construction and operation cost of an industrial device is lowered.

Description

technical field [0001] The invention belongs to the technical field of chemical production, and in particular relates to a recovery method and equipment for methyl chloride tail gas in the chemical production process. Background technique [0002] In the production process of methylchlorosilane and methane chloride at present, except containing a large amount of non-condensable gases (such as: N 2 、CH 4 , HCl, C 2 h 6 ), also contains a large amount of methyl chloride (accounting for 20% ~ 55wt% of the total non-condensable gas). In the current industrial production, for the recovery of methyl chloride gas in the non-condensable gas, the conventional method of low-temperature condensation of methyl chloride + gas-liquid separation is mostly used. This method requires the use of cryogenic refrigerant, low operating temperature, high equipment investment, and chlorine The methane recovery effect is not high (recovery rate of methyl chloride ≤ 90%), resulting in higher ener...

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Problems solved by technology

[0004] Chinese patent CN 101870709B discloses a method for absorbing methyl chloride gas in noncondensable gas by using crude chlorosilane as an absorbent. This method can reduce the content of methyl chloride in noncondensable gas to ≤0.5wt%, but the absorption temperature is - 25~-40℃, the operating temperature is low, and the energy consumption and equipment investment are relatively large

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