Optimization Of Clean Production Process For Polyvinyl Chloride Synthesis

Polyvinyl chloride(PVC) as an important plastic products, widely used in building materials, light industry, agriculture and packaging, etc. Polyvinyl chloride production was of high energy consumption, high material consumptions and high pollution problems, was one of the important industry of the national "three highs" control industries. Therefore, polyvinyl chloride industry was full of necessary to carry out the cleaner production research. Calcium carbide method had become a mainstream technology of polyvinyl chloride production in our country, and accounts for about 80% in the total capacity of PVC production in our country. This paper mainly study of Polyvinyl chloride cleaner production synthetic process by calcium carbide method.Through the comparative analysis about resources and energy consumption,production technology and equipment, pollutants and recycling of acetylene production section, vinyl chloride synthesis section and PVC polymerization section, select vinyl chloride synthesis section as the key section of PVC cleaner production evaluation.Using AHP-fuzzy mathematical comprehensive evaluation to evaluate the key section cleaner production level of one PVC production project in Heilongjiang province.Using Analytic Hierarchy Process(AHP) to establish the cleaner production evaluation index system of vinyl chloride section, and calculate the index weight. There were 5first grade indexes, production technology and equipment index weight was the largest(0.4158). And the pollutants index was followed, with the weight of 0.2470. Showed that the production technology and equipment index has the greatest impact on PVC cleaner production level. There are 19 secondary indicators, equipment automation degree index weight was the largest(0.2283). And the process selection reasonability,high boiling residual liquid comprehensive utilization and the total mercury in waste water index was followed, with the weight of 0.1035, 0.0945 and 0.0873 respectively.Indicated that equipment automation degree has the greatest influence on PVC cleaner production level.Using fuzzy mathematics comprehensive evaluation method to evaluate the key section cleaner production level. The comprehensive evaluation index was Y =(0.2715,0.2472, 0.4818). The maximum membership degree of vinyl chloride section cleaner production level was in the third grade(0.4818), showed that cleaner production level of the vinyl chloride section was in the domestic cleaner production basic level. The maximum membership degree of production technology and equipment indicator and environmental management requirements index were 0.8430, 0.6000 respectively, all in the third grade. The maximum membership degree of pollutants index was in the second level(0.4142). Showed that improving production technology and equipment,reduce pollutants and strengthen production process environmental management were the keys to improve the cleaner production level of vinyl chloride section.This paper puts forward main method optimizing production processes and equipment were as follows: optimized the process control parameters, choose mercuric chloride/ low-mercury catalyst active carbon catalyst which Hg Cl2 mass fraction was5.0%~6.0%, choose the compound bed vinyl chloride synthesis reactor instead the fixed bed reactor. The measures of reducing pollutants were as follows: mercury wastewater collected separately, using chemical precipitation process to deal with the mercury-containing wastewater. Acetylene clean by sodium hypochlorite clean technology optimized to the mass fraction of 98% sulfuric acid purity. The measures of strengthen the environmental management during production process were as follows:set up environment management organization and environmental monitoring institution with professional and technical personnel. Strengthen the management of environmental protection facilities, ensure pollutant discharging up to standard.Again used the AHP-fuzzy mathematics comprehensive evaluation method to evaluate the optimized vinyl chloride section clean production level. Thecomprehensive evaluation index was Y’ =(0.2884,0.4393,0.2724). The maximum membership degree of vinyl chloride section cleaner production level was in the second stage(0.4393). The maximum membership degree of vinyl chloride section cleaner production level increased from the third stage to the second stage. Showed that the optimized cleaner production level of the vinyl chloride section was in the domestic cleaner production advanced level.