Oxidative pyrolysis process of dinitrotoluene wastewater

Abstract

The invention discloses an oxidative pyrolysis process of dinitrotoluene wastewater. The oxidative pyrolysis process comprises the following steps of: passing wastewater from a washing kettle through a buffer tank, a settling tank, a preheater, a high pressure pump, a pyrolytic preliminary heat exchanger, a pyrolytic hot oil heat exchanger, a pyrolysis reactor, a pyrolysis cooler and a buffer tank to be discharged, wherein an oxidant is added at an inlet of the settling tank and / or the pyrolytic preliminary heat exchanger; and the oxidant is added into the pyrolytic preliminary heat exchanger through pressurization. According to the process, the chromaticity of the wastewater processed by the oxidative pyrolysis process is reduced by 25-30 percent in comparison with the conventional process, the scaling in the heat exchanger of the system can be effectively reduced, the operation cost can be reduced, and the content of aromatic nitro compounds (dinitrotoluene, nitrocresol and the like) in the wastewater after treatment is reduced by 25-30 percent compared with that in the conventional process.

Description

technical field [0001] The invention specifically relates to a dinitrotoluene wastewater oxidation pyrolysis process. Background technique [0002] In the dinitrotoluene process, there is a stream of wastewater from the alkaline washing section of dinitrotoluene, containing aromatic nitro compounds or two or more mixtures thereof, such as: nitrocresol, dinitrocresol, three Nitrocresol, dinitrotoluene, mononitrotoluene, etc., the wastewater is heated to 150°C-300°C at pH 7-14, pressure 10-15MPa, anaerobic, air-free or oxygen-free. figure 1 As shown, the wastewater from the washing tank passes through the buffer tank, settling tank, preheater, high-pressure pump, pyrolysis pre-heat exchanger, pyrolysis heat oil heat exchanger, pyrolysis reactor, pyrolysis cooler, and the buffer tank is discharged . The final waste water contains 10 ppm of mononitrotoluene + dinitrotoluene, and 100-150 ppm of nitrocresols. [0003] Problems and shortcomings of the existing wastewater pyrolys...

AI Technical Summary

Problems solved by technology

[0004] 1. After treatment, the chroma of wastewater is still high

[0005] 2. Severe fouling in a heating heat exchanger during the operation of the original pyrolysis

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