High-efficiency and energy-saving caprolactam recovery technology

Abstract

The invention relates to an aqueous caprolactam solution concentration method. The method comprises steps as follows: 1), extract water is preheated through a heat exchanger by the aid of a pump I, and enters an evaporation pipe through a top inlet of a single-effect falling-film evaporator; 2), the extract water is distributed by an in-tower liquid distributor, is distributed in a heat exchange pipe in a film-like mode and is subjected to thin film evaporation through steam heating outside the pipe when entering a pipe cavity by the aid of gravity flow, and the extract water and secondary steam in the pipe flow down to the bottom of an effect body and enter a single-effect separation tank for liquid-steam separation; 3), a concentrated solution at the bottom of the effect body and the bottom of the separation tank is sent to the top of a two-effect falling-film evaporator through a pump II, and the concentrated solution of the two-effect falling-film evaporator is subjected to liquid-steam separation through a pump III, a pump IV and a two-effect separation tank; 4), the concentrated solution is sucked by a pump V from the bottom of the effect body and sent into the top of a three-effect falling-film evaporator for circulating concentration, and the technological requirement is met.

Description

technical field [0001] The invention relates to a high-efficiency and energy-saving caprolactam aqueous solution concentration process, which adopts a process route combining falling film evaporation with mechanical steam and compressor heating technical background [0002] The polymerization reaction of nylon 6 is an equilibrium reaction, and about 8% to 10% of monomer caprolactam and cyclic oligomers will inevitably be produced during production. These cyclic oligomers, especially cyclic dimers, will affect the polymerization process. Serious hazards are caused. In actual production, about 1:1 deionized water is used to extract and wash the polymerized nylon 6 slices. After extraction, the deionized water becomes extracted water containing about 10% caprolactam and oligomers. Concentrate and recycle. [0003] The traditional caprolactam water concentration process is generally a three-effect evaporation process. In the production process, 1.0MPa(G) steam is required as a ...

AI Technical Summary

Problems solved by technology

[0003] The traditional caprolactam water concentration process is generally a three-effect evaporation process. In the production process, 1.0MPa(G) steam is required as a heat source to directly heat the caprolactam aqueous solution.

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