城市生活垃圾制备水泥窑用衍生燃料的性能分析

Analysis of the behaviors of the fuel for cement-making from the refuse left-over by the rural solid waste

由城市生活垃圾制备了衍生燃料(RDF),并对其性能进行了分析。结果表明,该燃料着火点低、燃烧速度快、燃烬时间短,其燃烧包括4个阶段:水分蒸发释放、挥发分释放与有机物的裂解、挥发物可燃组分的快速着火燃烧和焦炭物质的燃烧。垃圾衍生燃料主要由挥发分和灰分构成,热量主要来自于挥发分中的可燃物燃烧,热值不高。用联合质谱-热重分析了挥发分的释放特性及有害气体的产生过程。RDF燃烧后的灰分主要成分与水泥熟料矿物的化学成分一致。研究表明,可以利用水泥生产线对RDF进行工业化协同处理。

The article is aimed to introduce an analysis of the behav iors of the fuel for cementmaking from the refuse leftover by the ru ral solid waste. For this purpose, we have investigated a thermal be havior of the refusederived fuel （RDF） prepared from the rural mu niciple solid waste （MSW）in the combustion process by means of in tegrated thermal analysis （20 K/min, ranging from ambient tempera ture to 1 273 K） . We have also studied the combustion process and the characteristic features of RDF from the coal ignition and burnout. The results of our study indicates that it is the emission of the volatile matter that controls the combustion of RDF. In addition, the regions of RDF （with its four peaks） proves to be more complex than the coal itself （two peaks）. What is more, with the increase of temperature, the combustion process of RDF in the air can be divided into four stages, that is, the loss of free water （60 ℃ to 165 ℃ ）; the loss of the structural water, the generation and burning of the small molecules from the crack of large molecules with the generation of large amounts of harmful substances （230 ℃ to 360 ℃ ） ; the rapid ignition and combustion of the combustible components of the volatiles （380 ℃ to 530 ℃ ）; and, the coke combustion （620 ℃ to 740 ℃ ）. Another point to be mentioned is that since RDF has a lower ig nition temperature, it is necessary to experience a more intense com bustion process, a faster burning rate and shorter time for its comple tion. For example, the ignition temperature （ Ti ） should be set be tween 230 ℃ and 260 ℃, whereas the maximum combustion rate （DTGmax） should be 3.5%/min 5%/min with the corresponding temperature being from 280 ℃ to 300 ℃, that is, much higher than that for coal, but its calorific value needn＇ t be high for it is mainly done from the combustion of volatile. We have also studied the volatile release characteristics and the harmful gas release process by integrating the thermal analysis system coupled with a mass spectrom eter. And, finally, we have done an Xray fluorescence analysis for measuring the ash components of RDF and the main components of RDF ash （CaO, SiO2, Al2O3, Fe2O3, MgO）, which prove to be consistent with the cement clinker. From what has been mentioned above, it can be concluded that RDF proves to be feasible to be used as a fuel in the cement kiln to deal with the MSW, though the high content of sulfur, chlorine and alkali are likely to cause the abnormity of cement kiln and the quality of the cement.