Study Of Cleaner Production Audit In Trichlorosilane Industry

Cleaner production is an advanced concept of pollution prevention, which involves a wide range of Pan-Wai and a lot of implementation modalities. The purpose of the cleaner production is to save energy and material consumption, and reduce pollution emissions, and increase production efficiency, which decided that cleaner production audit is the most important way to carry out cleaner production, especially for those manufacturers which consume much energy and material, or emit a large number of wastes. To further strengthen the cleaner production audit in major enterprises, in July2008, Department of Environmental Protection issued a notice which indicates that China has introduced a relatively comprehensive regulation system on clean production. Although trichlorosilane has a wide range of uses and a good prospect, its production process including many devices, high material and energy consumption, is somewhat complicated. In addition, the production process also involves many toxic and hazardous substances. Conducting cleaner production audit in trichlorosilane producing industry could achieve tremendous environmental, economical and social benefits at the same time.This thesis focuses on the cleaner production audit that a trichlorosilane producing enterprise in Henan Province has implemented, explores in which way the basic principles, ideas, and approaches of cleaner production audit could be used in the seven stages and35steps of the auditing process, and then summarizes the problems and suggestions encountered. The main content of the seven stages including work requirements, implementing methods, and auditing results, are as follows:â‘ The first stage details the overall work plan and Training status of all staff;â‘¡The second stage conducts a comprehensive survey on the state of the enterprise through the eight directions of cleaner production audit;â‘¢About the key part of this auditing progress, the third stage checks the material conservation, and analyzes the reasons for waste producing.â‘£The fourth stage describes the general approach, content, and procedures of program researching, based on one of the medium/high cost programs;⑤With an example which is the same as in stage four, the fifth stage illustrates the general approach of the feasibility analysis of medium/high cost programs;â‘¥The sixth stage introduces the implementing plans and results of all proposed programs;⑦The sixth stage elaborates the continuous cleaner production plan that the enterprise has formulated.In the audit process,46schemes were put forward. Of all the schemes, two are unfeasible, and the others which are feasible were fully implemented. The enterprise that was audited has made a lot of benefits some of which are as follows:The use efficiency of silicon and the conversion rate of trichlorosilane have both been improved.Steam consumption of per unit of product has been reduced from1.20t to1.06t, saving about5600t of steam each year.Silica residue emission of per unit of product has been reduced from13.1kg to5.55kg, which could lead to a decrease of328t/a in solid waste emission.Plant wastewater emission of per unit of product has been reduced from0.89t/t SiHCl3to0.85t/t SiHCl₃, which could reduce about1376t wastewater volume each year.Electricity consumption of per unit of product has dropped from200kWh to195kWh, which could reduce about10000kWh each year.In addition, the equipment failure rate has been cut down, and the production efficiency has been significantly improved.