Tandem ammonium sulfate crystallization method and device

Abstract

The invention discloses a tandem ammonium sulfate crystallization method and device, and belongs to the field of chemical engineering. According to the device, two crystallizers connected in series are used, a two-effect vacuum crystallization process is adopted, the first effect is neutralization evaporation, and the second effect is evaporation crystallization. An ammonium sulfate solution withthe concentration of about 40% neutralized and evaporated is fed into the second effect section of an evaporative crystallization system so that ammonium sulfate with a large-particle ammonium sulfateproportion is obtained. According to the device, gas ammonia dissolution heat and neutralization heat of sulfuric acid and ammonia neutralization reaction are fully utilized, and secondary steam of the neutralization evaporator is used as a heat source, so that the consumption of circulating water is reduced, the proportion of large-particle ammonium sulfate is increased, and meanwhile, the coating loss of caprolactam is reduced.

Description

Technical field: [0001] The invention relates to the field of chemical equipment, in particular to a series-connected ammonium sulfate crystallization method and a device thereof applied in a caprolactam equipment. Background technique [0002] Caprolactam is an important organic chemical raw material, mainly used in the production of nylon 6 engineering plastics and nylon 6 fibers. Nylon 6 engineering plastics are mainly used as components and components of automobiles, ships, electronic appliances, industrial machinery and consumer goods, etc. Nylon 6 fibers can be made into textiles, industrial yarns and carpet yarns, etc. Platelet drugs, the production of laurocaprazine, etc., have a wide range of uses. The main production methods of caprolactam are: [0003] 1. Cyclohexanone-hydroxylamine method [0004] This method is the main method of producing caprolactam with cyclohexanone as raw material. Among them, there are three production process routes of hydroxylamine, ...

AI Technical Summary

Problems solved by technology

[0024] a) In the single DTB type ammonium sulfate neutralization crystallizer widely used at present, most of the ammonium sulfate solid particles are 0.6-1.2mm, and the ratio of ammonium sulfate solid particle size above 2mm is less than 10%, usually at about About 5%, the proportion of ammonium sulfate crystals above 2mm is small, and the solid particle size is small. Because the price of large-grained ammonium sulfate crystals is about 30-45 US dollars / t ammonium sulfate higher than that of small-grained ammonium sulfate crystals, that is, about 200-300 RMB / t ammonium sulfate, ammonium sulfate caprolactam plant has a large output of ammonium sulfate, about 1.5t ammonium sulfate / t caprolactam, this technology with a small proportion of large ammonium sulfate particles results in poor economic efficiency of the ammonium sulfate crystallization plant

[0025] b) At present, the content of caprolactam in ammonium sulfate crystals is usually about 0.1%wt, resulting in the loss of caprolactam, and there is still room for reducing the loss of caprolactam in technology;

[0026] c) A single DTB type ammonium sulfate neutralizes the secondary steam generated at the top of the crystallization tower, which is generally cooled by circulating cooling water. The energy is not properly utilized, and the cooling water consumption is relatively large.

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