Method and apparatus for f toluene oxidation tail gas treatment

Abstract

The present invention relates to a method and an apparatus for toluene oxidation tail gas treatment. The apparatus comprises an adsorption device, an absorption tower, a desorption tower, a water washing tank, a decanter, an absorbent storage tank, a condensate decanter, a distillation tower, and a venting system. The toluene oxidation tail gas treatment process comprises that toluene oxidation tail gas and an absorbent are subjected to countercurrent contact in the absorption tower and mass transfer is performed, benzene-toluene-removing tail gas is adsorbed with active carbon in the adsorption device and then is vented, the absorbed liquid is subjected to water washing through the water washing tank, separation is performed with the decanter, the separated oil phase is desorbed in the desorption tower, the desorbed liquid phase reaches the absorbent storage tank and is recycled, the water phase reaches an environmental protection device and is treated, the gas phases of the desorption tower, the water washing tank and the decanter are separated in the condensate decanter, the separated light phase is distilled through the distillation tower, and the distilled gas is recovered in an aromatic hydrocarbon recovery unit. According to the present invention, the toluene oxidation tail gas is subjected to the absorption-desorption and adsorption-desorption combined treatment, the tail gas achieves the stable emission standard, the aromatic hydrocarbon is recovered, and the water washing tank and the decanter are additionally arranged so as to effectively prevent the clogging of the tower tray and the bed layer through the acid crystal.

Description

technical field [0001] The invention belongs to the technical field of recovery and treatment of chemical waste gas, and relates to the recovery and treatment of industrial tail gas produced by caprolactam, in particular to a method and device for treatment of toluene oxidation tail gas. Background technique [0002] The production of caprolactam by the toluene process uses toluene as a raw material, and the oxidation of toluene to produce benzoic acid is carried out in a tank reactor with air as an oxidant. Restricted by the reaction characteristics and system physical properties, the single-pass conversion rate of the toluene oxidation reactor is generally maintained at about 15%, the gas phase load is very large, the nitrogen in the air and the unreacted oxygen must be discharged from the tail gas system, and the benzene-toluene in the tail gas Content about 7~11g / Nm 3 , Direct discharge will cause serious air pollution, cause the enterprise's waste gas discharge to fail...

AI Technical Summary

Problems solved by technology

Due to the limited adsorption capacity of the adsorbent, short life (design life of 3 years), frequent regeneration and huge steam consumption, and the adsorption capacity of activated carbon will gradually decrease during the production process, the recovery rate of aromatics cannot be guaranteed

The content of benzene-toluene in the exhaust tail gas is about 0.9~1.5g / Nm 3 , can no longer meet the requirements of the "Comprehensive Emission Standard of Air Pollutants" (GB16297-1996)

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