System and method for reclaiming hexanolactam from rearrangement mixture

Abstract

The invention relates to a system and a method for reclaiming hexanolactam from a rearrangement mixture, wherein the system comprises a neutralization unit, a buffer unit, a cache unit, a temporary extraction unit, an extraction unit and a reclaiming unit, wherein the buffer unit is used for receiving crude amide solution which is sent in by the neutralization unit and has the impurity content lower than a standard value; the cache unit is used for receiving the crude amide solution which is sent in by the neutralization unit and has the impurity content higher than the standard value; the temporary extraction unit is used for performing batch extraction and separating out first amide solution; the extraction unit is used for performing continuous extraction and separating out second amide solution; and the reclaiming unit is used for reclaiming the hexanolactam. The system sends the crude amide solution into the extraction unit to perform the continuous extraction or sends the crude amide solution into the temporary extraction unit for performing the batch extraction according to the quality of the crude amide solution respectively first so as to maintain the continuous operationof the process, improve the separation efficiency, reduce the raw material consumption, and simultaneously reduce the load of the subsequent purification steps.

Description

technical field [0001] The present invention relates to a system and method for recovering caprolactam from a rearrangement mixture, in particular to a system and method for recovering caprolactam from a rearrangement mixture of cyclohexanone oxime and sulfuric acid. Background technique [0002] Caprolactam (CPL for short) is an important raw material for the synthesis of chemical products such as nylon 6 and nylon 6.6, and also occupies a very important position in the modern organic chemical industry. The common industrial method uses cyclohexanone oxime to carry out liquid-phase Beckmann transposition reaction with oleum to produce caprolactam. After the reaction, it contains a mixed liquid of oleum and caprolactam, and then neutralizes it with ammonia water to generate ammonium sulfate. Ammonium sulfate and crude amide containing impurities are separated, and the crude amide is extracted with an organic solvent, followed by subsequent purification and separation to reco...

AI Technical Summary

Problems solved by technology

However, due to the high impurity content of the cyclohexanone oxime raw material or the incomplete reaction at the initial stage, inferior crude amide solution may be formed, so that in the subsequent organic solvent extraction process, an inseparable third layer is produced between the organic phase and the aqueous phase, resulting in The operation of the continuous extraction device is abnormal, and the inorganic liquid and impurities overflow to the subsequent purification steps along with the amide solution, resulting in a sudden increase in the load of the subsequent purification steps, a decrease in separation efficiency, and loss of raw materials, which further interrupt the continuous process operation and shut down

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