新型干法水泥生产中二恶英减排的环境技术经济研究

分析了水泥生产过程中多氯二苯并对二恶英和多氯二苯并呋喃(以下简称“二恶英”)的产生机理和国内外排放情况，针对我国部分新型干法水泥窑生产工艺二恶英排放偏高和窑炉能效偏低的问题，选择典型的新型干法水泥窑，开展了二恶英、常规污染物排放情况监测和能效检测及诊断，提出了二恶英协同减排措施，实施了有针对性的技术改造，并对改造后的排放和能效改进情况、环境和经济效益进行了系统评估. 结果表明:采用提高能效、充分燃烧、快速冷却废气及确保进入除尘器的废气温度低于200 ℃等二恶英减排最佳可行技术，烟气中二恶英的量降低了91.8%，单位熟料的能耗水平降低了2.08%；同时，颗粒物等常规污染物和二氧化碳等温室气体也实现了协同减排. 企业通过节能和余热利用获取了经济效益. 

Environmental and Economic Study on Dioxin Reduction during Cement Production in a New Dry Cement Rotary Kiln

Formation mechanisms of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) during cement production and their emission status at home and abroad were analyzed. Because relative higher dioxin emission concentrations and lower thermal energy efficiency were detected in some cement kilns, countermeasures to reduce dioxins and other conventional pollutants simultaneously were proposed based on the monitoring results of these pollutants as well as an energy audit and diagnosis in a typical new dry cement rotary kiln. The measures of simultaneous reduction for dioxins and other conventional pollutants were carried out. The changes in the emissions of dioxins and conventional pollutants as well as energy efficiency were evaluated, and the corresponding environmental and economic benefits were systematically analyzed. Results indicated that optimal and feasible reduction measures consisting of energy efficiency enhancement, sufficient combustion, quick cooling of flue gas and lowering the ESP entrance temperature of the flue gas below 200 ℃, etc., were able to enable dioxin reduction of 91.8% as well as reduction of 2.08% in energy consumption per unit clinker production. Conventional pollutants, such as particulates, and greenhouse gases, such as carbon dioxide, were reduced simultaneously. The retrofitted enterprise gained notable economic benefits by energy saving and heat recovery.