Device for removing nitrotoluene with dilute nitric acid after denitrification of nitrotoluene waste acid

Abstract

The invention relates to the technical field of nitrotoluene production, in particular to a device for removing nitrotoluene with dilute nitric acid after denitrification of nitrotoluene waste acid, comprising sequentially connected coolers, separators, collection tanks, nitrogen oxide compressor units, and nitrogen oxide The outlet pipeline of the compressor unit includes the gas pipeline leading to the nitrogen oxide absorption tower, the liquid pipeline leading to the separator through the regulating valve, and the flash evaporator; the separator is equipped with a nitrotoluene discharge pipe and a first density meter for detecting the density of nitric acid; The outlet of the nitrogen compressor unit is provided with a second density meter for detecting the density of nitric acid. The upper ends of the cooler, separator, and flash evaporator are connected to the smoke pipe through the gas pipeline, and the smoke pipe is connected to the inlet of the nitrogen oxide compressor unit. The structure of the invention is scientific. By adjusting the concentration of nitric acid produced by the nitrogen oxide compressor unit and returning it to the separator, the concentration of nitric acid in the separator is adjusted so that the density of nitric acid and nitrotoluene is different, thereby separating nitrotoluene.

Description

technical field [0001] The invention relates to the technical field, in particular to a device for removing nitrotoluene with dilute nitric acid after denitration of nitrotoluene waste acid. Background technique [0002] Nitrotoluene is an intermediate in the production of a variety of fine chemicals. It is widely used in industry. It is composed of three isomers of nitrotoluene, o-nitrotoluene and m-nitrotoluene. After separation, the three pure products are all It is an important raw material for organic chemical synthesis. [0003] In the process of producing nitrotoluene, a large amount of waste acid containing sulfuric acid and nitric acid is produced. At present, the more advanced waste acid treatment process in the world uses vacuum concentration of waste sulfuric acid and pressure absorption of nitrogen oxides. In the process of vacuum compression, denitrification The process generally produces condensed dilute nitric acid with a concentration of 15%-40%. The nitrog...

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Problems solved by technology

[0004] In the above process, the nitrotoluene contained in the waste acid enters the condensed dilute nitric acid with the denitrification process, resulting in a large amount of free nitrotoluene in the condensed dilute nitric acid. The density of the dilute nitric acid ranges from 1.1kg / L to 1.25 kg / L , the density of nitro compounds is about 1.19 kg / L, the density of the two materials is very similar, it is difficult to achieve continuous separation of free nitro compounds from dilute nitric acid

If the nitrotoluene is not removed, on the one hand, a large amount of nitro compounds will be wasted; on the other hand, side reactions and impurities will occur in the subsequent nitration production of the finished dilute nitric acid

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