堆积参数对MSW生物干化的影响

Impact of the piling of parameters on the MSW drying process

采用生物干化技术来处理高含水率城市生活垃圾(Municipal Solid Waste,MSW),研究了堆积高度(0.75 m、1.0 m、1.2 m、1.5 m)、堆积密度(0.46×10~3~0.64×10~3kg/m^3)对城市生活垃圾生物干化的影响。通过生物干化装置和数据收集系统监测MSW生物干化过程中温度、含水率、挥发性固体(VS)质量分数、热值的情况。微生物发酵的产热量通过堆体内部温度的累积来表征。经过15 d的生物干化试验,当垃圾堆积高度为1.2 m、堆积密度为0.51×103kg/m^3时,垃圾的含水率降到最低,仅为33.6%,低位热值提高130%,达到12 264 k J/kg。试验产物的平均低位热值提高到10 973 k J/kg,达到制备垃圾衍生燃料的要求。结果表明,通过优化垃圾的堆积参数,可有效提高垃圾含水率下降幅度、单位质量垃圾水分去除率、单位质量垃圾有机物降解率和低位热值。

This paper is intended to present a bio-drying method to treat the municipal solid waste （MSW） with high grade of moisture. In the paper, we have made an investigation of the bio- drying process of MSW as well as that of the effect of the stacking heights（0.75 m, 1.0 m, 1.2 m and 1.5 m, respectively）in ad- dition to the stacking densities（0. 46 × 103 -0. 64 ×103 kg/m3 ）. Furthermore, what we have also wanted to detect is the tempera- ture for the drying process, the moisture content rate, the volatile solids （VS） and the minimal heating value （MHV） of the highmoisture content MSW via a biological drying device in combina- tion with a data acquisition device. The so-called bio-drying experiments the process involves can be divided into two groups, by one of which the stacking height can be controlled as a variable with the stacking density used as a constant. And, by the other group, the stacking density can be controlled as a variable, with the stacking height taken as a constant. When the bio-drying ex- periment has been done 15 days later, the stacking height would become equal to 1.2 m and the inner accumulated temperature of MSW stacking would reach its highest limit in the first experiment. On the contrast, the moisture content may tend to decrease by 34. 8% while the VS content tends to decrease to 78. 3%. And, simultaneously, the heat value may tend to increase to 11 158 kJ/kg. Furthermore, when the stacking density comes to 0. 51 × 10a kg/m3, the inner cumulated temperature of MSW stacking is likely to reach its highest limit in the second experiment, on the condition, when the moisture content may turn to decrease to 33.6%. Meanwile, the VS content which has been affected by the moisture content is likely to drop to 79% of its original with its heat value reaching 12 264 kJ/kg. Thus, in comparison with the original MSW, the average volume of the product LHV under the experimental condition would increase to 10 973 kJ/kg, which should be considered to be able to meet the requirements of the refuse-derived fuel （RDF） to be obtained. Thus, the results of our experiment prove to be effective to increase the MSW bio-drying efficiency through optimizing the stacking height and stacking density, which helps to reduce the water content of MSW and heighten the organic substance degradation rate in the average initial humid waste and LHV value.