What are the differences between calcium carbide method PVC and petroleum method PVC?
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As early as 1835, French Regnauk had discovered vinyl chloride. It was not until 1912 to 1913 that German chemists F. Klate and E. Zacharis developed the industrial production methods of vinyl chloride and polyvinyl chloride. Large-scale emulsion polymerization was not realized by Bitterfeld until 1935. In 1940, the Goodrich Company in the United States created suspension polymerization. Since then, the PVC industry has begun to develop. The world's PVC technology has developed for more than 60 years, and China's PVC has experienced more than 40 years of development. China has developed from the absolute advantage of the petroleum method to the current dominance of the calcium carbide method (not to mention foreign countries). During this period, it has gone through many development processes. To this day, what are the differences between calcium carbide method PVC and petroleum method PVC in terms of production scale, process technology, control technology, resin quality and product quality? Please express your opinions!
The quality of petroleum method is better than that of calcium carbide method
The main reason is that the VCM process is different. The calcium carbide method uses calcium carbide to produce acetylene, which reacts with hydrogen chloride to produce vinyl chloride. The petroleum method uses petroleum to make ethylene, reacts with chlorine to form dichloroethane, and then oxidizes it to vinyl chloride. At present, there are two processes for producing acetylene by calcium carbide method: dry process and wet process. ； Hydrogen chloride and chlorine gas generally come from the chlor-alkali industry. The polymerization process of PVC is similar, and most of them now use the suspension method. The quality of PVC finished by the petroleum method is better than that of the calcium carbide method, and it has wider uses and a slightly higher price. In foreign countries, petroleum law is generally dominant, but a stable source of ethylene is required. Most of the domestic calcium carbide method is mainly used because the chlor-alkali capacity expansion has been too fast in recent years. In order to balance the downstream chlorine, it has to be used as a last resort because of the lack of enough ethylene. In fact, the calcium carbide method consumes a lot of energy, is highly polluting, and is highly dangerous, so it is not an ideal process.