A production system and method for caprolactam dehydration

Abstract

The invention discloses a production system of dehydrated caprolactam and a method thereof. The system is characterized by comprising a first-efficiency heat exchanger, a first-efficiency evaporator, a second-efficiency heat exchanger, a second-efficiency evaporator, a third-efficiency heat exchanger and a third-efficiency evaporator which are sequentially connected and then connected with a rectifying tower. The production method comprises the following steps of: pre-heating the materials and then sending the materials to the first-efficiency evaporator for evaporation under the conditions of a temperature of 115-125 DEG C and a pressure range from 0.2 to 0.35MPaG; heating the materials and sending the materials to the second-efficiency evaporator for evaporation under the conditions of a temperature of 105-110 DEG C and a pressure range from 0.05 to 0.1MPaG; heating the materials and sending the materials to the third-efficiency evaporator for evaporation under the conditions of a temperature of 85-95 DEG C and a pressure range from 0.05 to 0.08MPaG; and sending the materials to the rectifying tower for rectification under the conditions of a temperature of 90 DEG C and a pressure range from 0.05 to 0.08MPaG, wherein the dehydrated caprolactam with less than 0.001% of water is obtained at the bottom of the rectifying tower. The invention has the advantages that multiple effective and gradient utilization of steam is realized through rational control of pressure and temperature, a large amount of cold and heat are saved, and the thermal decomposition of the caprolactam is reduced at a lower operating temperature.

Description

technical field [0001] The invention relates to a production system and method for caprolactam dehydration. Background technique [0002] Caprolactam (CPL for short) is one of the important organic chemical raw materials. Its main purpose is to produce polyamide chips (usually called nylon-6 chips or nylon-6 chips) through polymerization, which can be further processed into nylon fibers, engineering plastics, plastics, etc. film. The industrial production of caprolactam is to make cyclohexanone oxime undergo Beckmann rearrangement reaction under the condition of fuming sulfuric acid to generate caprolactam. After the rearrangement reaction, the mixed aqueous solution containing fuming sulfuric acid and caprolactam is neutralized with ammonia water to produce Ammonium sulfate, then separate and purify ammonium sulfate and crude amide. Usually, the organic solvent benzene is used for the first extraction, and then the water is used for the second extraction to release the ca...

AI Technical Summary

Problems solved by technology

[0003] The existing caprolactam dehydration process and production system are usually evaporation and flash evaporation, and the water in the caprolactam aqueous solution is evaporated and removed by the evaporator. However, as the water content of caprolactam decreases, the dehydration temperature required for the caprolactam material gradually increases. High, it will lead to the decomposition and deterioration of caprolactam, and at the same time, due to the change of water content, the heat grade required for evaporation will be different

Therefore, the temperature in the dehydration process of caprolactam should not be too high, and at the same time, the caprolactam material will dehydrate through heating, and the dehydrated moisture will be converted into steam to be condensed and cooled.

Therefore, the dehydration of caprolactam is only realized through the conventional evaporation process, which not only consumes a lot of energy, but also the water content of caprolactam is difficult to reach the standard, which may lead to the deterioration of caprolactam and affect the product quality

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