VOC gas and nitrogen separation and recovery system in calcium carbide method polyvinyl chloride production process

The invention belongs to the technical field of separation and recovery of exhaust gas in the industry of PVC (polyvinyl chloride) production by a calcium carbide method, and particularly relates to a system for separating and recovering VOC (volatile organic compound) gas and nitrogen in the PVC production process by the calcium carbide method. The system comprises a gas holder inlet pipeline, a buffer gas holder, a compressor inlet pipeline, a compressor, a compressor outlet pipeline, a front cooler, a pipeline between coolers, an aftercooler, a cooler outlet pipeline and a pressure swing adsorption separation device which are communicated with one another, and a purified gas outlet of the system is sequentially communicated with a nitrogen output pipeline and a nitrogen buffer tank; and a recovered gas outlet of the gas recovery device is sequentially communicated with a VC and acetylene gas output pipeline and a VC and acetylene buffer tank. According to the invention, the exhaust gas containing VC, acety