A kind of evaporation concentration method and equipment of cyclohexane oxidation waste lye

Abstract

Disclosed are a method and equipment for evaporating and concentrating waste lye from cyclohexane oxidation. The method of the present invention first uses water vapor to directly contact the spent lye of cyclohexane oxidation to carry out continuous stripping to obtain the gas phase and waste lye after stripping; After the extraction, the waste caustic liquid is combined with the circulating hot caustic liquid to obtain the tower bottom liquid, and steam for stripping is generated; finally, a part of the tower bottom liquid is discharged as a concentrated liquid, and enters the secondary concentration process, and another part of the tower bottom liquid is carried out heating to obtain the circulating hot lye; the inventive method can effectively separate and recover effective products such as hexamethylene, cyclohexanone and cyclohexanol in the hexanaphthene oxidation waste lye, and meanwhile, avoid inorganic salt scaling in the equipment, Improve the safety of long-term operation of equipment. The evaporation concentration equipment of the present invention is simple and reasonable in structure.

Description

technical field [0001] The invention belongs to the field of preparing cyclohexanol and cyclohexanone by oxidation of cyclohexane, and in particular relates to a method and equipment for evaporating and concentrating spent lye from cyclohexane oxidation. Background technique [0002] In the existing process of preparing cyclohexanone by oxidation of cyclohexane, it is necessary to use an alkaline heterogeneous decomposition process to improve the decomposition conversion rate of cyclohexyl hydroperoxide produced in the oxidation process in the oil phase of cyclohexane, and at the same time neutralize the oxidation By-product organic acids and saponified organic esters, which inevitably produce an aqueous liquid waste called cyclohexane oxidation spent lye. A set of 120,000 tons / year cyclohexane oxidation to prepare cyclohexanone traditional process will produce more than 24t / h of oxidized waste lye. In the latest generation of cyclohexane oxidation to prepare cyclohexanone, ...

AI Technical Summary

Problems solved by technology

However, although it is only necessary to concentrate the solid content of spent caustic soda to 25-30% in the primary evaporator, due to defects in the original process design, a large amount of fouling will still occur during the evaporation process, which will affect the safety of long-term operation of the equipment.

[0004] In addition, due to the high solid content and high viscosity of the oxidized spent caustic soda, if it is necessary to heat up to 110 in the evaporator o Above C to make it evaporate, the tube wall temperature of the evaporator needs to be as high as 120 o Above C, and heat-sensitive substances such as cyclohexanone contained in the oxidized waste caustic soda are prone to condensation reaction under the condition of high temperature and high alkalinity in the evaporator, resulting in unnecessary product loss; meanwhile, due to the traditional gas-liquid separation The device is only a tray to recover the effective components in the vapor phase of the waste caustic soda, and the recovery efficiency is only 50%

In order to reduce the content of effective components in concentrated spent caustic soda, it is necessary to consume a large amount of heating steam to increase the evaporation of spent caustic soda, but the recovery efficiency of effective components is limited.

To sum up, the traditional waste alkali evaporation method can no longer meet the increasing economic, environmental protection and safety requirements, and a more reasonable evaporation method is urgently needed to replace it.

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