Continuous recycling method of NMP (N-methyl pyrrolidone) solvent for polyphenylene sulfide production device

The invention discloses a novel continuous recycling method of an NMP (N-methyl pyrrolidone) solvent for a polyphenylene sulfide production device. The polyphenylene sulfide production device comprises three vacuum rectifying towers, a heat exchanger, a centrifuge machine, a storage tank, a pump and relevant pipelines. In an existing polyphenylene sulfide solvent recycling process, pipelines are easily blocked by salt crystals in a dehydration process, so that the halt maintenance needs to be frequently carried out, the rate of equipment utilization is low, and the solvent loss is high. According to the novel continuous recycling method of the NMP (N-methyl pyrrolidone) solvent for the polyphenylene sulfide production device, a novel technological process device is developed; by virtue of forced circulation of high-concentration salt fraction at the tower bottoms, solid salt formed after water and the solvent are removed can be adequately stirred and circulated, and the blockage, caused by the salt crystals, of valves of the pipelines is avoided, so that the heating efficiency of the column bottoms is increased, the yield of NMP is improved, the quality of an recycled NMP product can reach 99.5% or above, recycling requirements of a system are met, and meanwhile, the long-period, stable and efficient operation of the device are guaranteed.