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

该提案的重点是减少波特兰水泥生产过程中产生的有害空气污染物（HAP），如碳氢化合物、盐酸、多氯二苯并对二恶英和多氯呋喃（PCDD/F）。在预热和干燥过程中，原料中有机物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这些hap形成的主要原因。一些工艺改进，如原料的热预处理、碳氢化合物循环的消除、预热废气传输管道的温度降低、增加氧化和预热器条件的改进，可能有助于减少和/或防止HAP的形成。提出了一个实验方案，以确定哪种策略是最有效的，以及需要哪些精确的工艺修改来实现它们。高温流动反应器，在200至700℃范围内运行，将用于研究原料碳氢化合物和氯在含有水泥窑原料和NOx， O2和水的环境中的形态，分配和反应。这些数据应该能够使设计特定的工艺修改，以防止在不增加控制装置的情况下从波特兰水泥窑形成和排放HAPs。

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.