Back-End Modifications of Portland Cement Plants to Reduce Emissions of Hazardous Air Pollutant

摘要9613422西德湖这项建议的重点是减少在波特兰水泥生产中产生的有害空气污染物，如碳氢化合物、盐酸、多氯二苯并对二恶英和多氯呋喃。原料中有机物在预热和干燥过程中的挥发以及空气污染控制(APC)装置和传输管道区域的条件似乎是形成这些HAP的主要原因。一些工艺改进，如原料的热预处理，取消碳氢循环，降低预热尾气输送管道的温度，增加氧化，以及改变预热器条件，可能有助于减少和/或防止这种HAP的形成。提出了一个实验计划，以确定这些策略中的哪一种最有效，以及需要进行哪些精确的流程修改才能实施它们。在200至700摄氏度范围内运行的高温流动反应器将用于研究生料碳氢化合物和氯在包含水泥窑原料和NOx、O2和水的环境中的形态、分配和反应。这些数据应该能够设计具体的工艺修改，以防止在不增加控制设备的情况下从波特兰水泥窑中形成和排放HAP。

Abstract 9613422 Sidhu This proposal focuses on the reduction of hazardous air pollutants (HAP) such as hydrocarbons, hydrochloric acid, and polychlorinated dibenzo-p-dioxins and polychlorinated furans (PCDD/F), produced in the production of Portland cement. Volatilization of organics from the feed stock during preheating and drying and conditions in the Air Pollution Control (APC) device and in the transfer ducting zones appear to be primarily responsible for the formation of these HAPs. Several process modifications such as the thermal pretreatment of feed stock, elimination of hydrocarbon recycle, temperature reduction in the preheat off-gas transfer duct, increased oxidation, and modification of preheater conditions may help reduce and/or prevent this HAP formation. An experimental program is proposed in order to determine which of these strategies is most effective and what precise process modifications are necessary to implement them. A high temperature flow reactor, operating in the range of 200 to 700 C will be used to study the speciation, partitioning, and reaction of raw meal hydrocarbons and chlorine in an environment containing cement kiln feed stock and NOx, O2, and water. This data should enable the design of specific process modifications to prevent the formation and emission of HAPs from Portland cement kilns without the addition of control devices.