Method for continuously and stably recovering aniline in aniline wastewater

Abstract

The invention belongs to the technical field of organic chemical raw material preparation, and relates to a method for continuously and stably recovering aniline in aniline wastewater. The method is characterized in that an aniline wastewater flow automatic control device is arranged on an aniline wastewater recovery pipeline to control the water content of aniline in an aniline crude product entering an aniline refining system; the aniline crude product enters an aniline refining system to prepare an aniline pure product; and the aniline wastewater flow control device comprises a conductivity meter. The aniline in the aniline wastewater is accurately recycled through the conductivity meter, the water content of the aniline in the recycling process is reduced, and the influence on the operation condition of the aniline primary distillation tower due to mixing of the wastewater is completely eradicated; and the recovered aniline and the separated crude aniline enter an aniline primary distillation tower together for refining, so that the water content of the aniline entering the primary distillation tower is less than 2.0%, and the stable operation of an aniline refining system is ensured.

Description

technical field [0001] The invention belongs to the technical field of organic chemical raw material preparation, and relates to a method for continuously and stably recovering aniline in aniline wastewater. Background technique [0002] Aniline is an important organic chemical raw material and chemical product, mainly used in the production of MDI, rubber additives and pharmaceuticals, dyes, pigments and intermediates. [0003] The reactants obtained by gas-phase hydrogenation of nitrobenzene to produce aniline are condensed and separated to obtain aniline wastewater and aniline crude product, because the specific gravity difference between aniline wastewater and aniline crude product is small (aniline 1.02kg / m 3 ;Water 1.00kg / m 3 ), in most cases the aniline wastewater produced by physical separation will carry part of the aniline into the aniline wastewater storage tank and accumulate continuously at the bottom of the tank. In order to recycle this part of aniline, it ne...

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Problems solved by technology

[0003] The reactants obtained by gas-phase hydrogenation of nitrobenzene to aniline are condensed and separated to obtain aniline wastewater and aniline crude product, because the specific gravity difference between aniline wastewater and aniline crude product is small (aniline 1.02kg / m 3 ;Water 1.00kg / m 3 ), in most cases the aniline wastewater produced by physical separation will entrain part of the aniline into the aniline wastewater storage tank and accumulate at the bottom of the tank. In order to recycle this part of the aniline, it needs to be recycled every 12 hours and directly enters the aniline initial distillation tower The initial distillation operation is carried out, but the waste water in the aniline is inevitably brought into the aniline initial distillation tower during the recovery process, resulting in severe fluctuations in the operating parameters of the aniline initial distillation tower, a large number of control indicators and alarms, which seriously damage the aniline refining process. The continuity and stability of the system operation will cause the low boiling content in aniline to increase, which will seriously affect the product quality

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