A circulating concentration device for dilute nitric acid produced by treating waste sulfuric acid in nitrotoluene

Abstract

The invention discloses a circulation concentrating device used for treating low-concentration diluted nitric acid generated from nitrotoluene waste sulfuric acid. The device includes a cooler, an auto-separator, a manual separator, a transition trough, a nitrogen oxide compression machine unit, and a nitrogen oxide absorption column, wherein the cooler, the auto-separator, the manual separator, the transition trough and the nitrogen oxide compression machine unit are successively connected through liquid pipelines. The outlet pipeline of the nitrogen oxide compression machine unit is dividedinto two paths, one is connected to the nitrogen oxide absorption column through a gas pipeline, and the other is continuously separated into two paths in parallel via liquid pipelines, one is connected to the auto-separator and the other is provided with a finish product outlet pipeline. The device is used for separation and concentration of nitrotoluene from the low-concentration diluted nitricacid during treatment of waste sulfuric acid, can increase usage value of the low-value diluted nitric acid and can solve problem of production balancing of the diluted nitric acid and increases economy of a waste sulfuric acid treatment device.

Description

technical field [0001] The invention relates to a chemical process for concentrating waste acid, in particular to a circulation concentrating device for dilute nitric acid produced by treating waste sulfuric acid from nitrotoluene. Background technique [0002] At present, the more advanced waste sulfuric acid treatment process in the world is the vacuum concentration of waste sulfuric acid and the pressure absorption of nitrogen oxides; the denitration process of waste sulfuric acid vacuum concentration generally produces condensed dilute nitric acid with a concentration of 15%-40%, such as waste sulfuric acid If it is nitrotoluene waste acid, the dilute nitric acid contains a large amount of free nitrotoluene; the nitrogen oxides produced in the waste sulfuric acid denitrification process are condensed and sent to the nitrogen oxide pressurized nitrogen oxide absorption tower for absorption, and the pressurized nitrogen oxide absorption tower generally adopts 0.65mPa worki...

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Problems solved by technology

[0003] Dilute nitric acid contains a lot of free nitro compounds; the density range of dilute nitric acid is 1.1kg / L-1.25kg / L, and the density of nitro compounds is about 1.19kg / L. The densities of the two materials are very similar, and it is difficult to achieve free Continuous separation of nitro compounds from dilute nitric acid; in the subsequent nitration production, a large amount of nitro compounds are wasted and combined side reactions produce

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