PVC塑料流化床气化试验研究

Experiments of PVC gasification in a fluidized bed

为开发城市生活垃圾低污染流化床气化与旋风燃烧熔融技术,研究了垃圾中广泛存在的PVC塑料在流化床内的气化特性与污染物生成机理.不同温度和过量空气系数下进行了流化床PVC气化试验,分析了不同工况对PVC中Cl转化为HCl的影响.实验结果表明,反应高于600 ℃、过量空气系数大约0.4时,Cl转化为HCl的选择性达到95%以上;气化效率达到22%～25%,气化气热值达到2 000 kJ/m3～2 300 kJ/m3.反应高于700 ℃,PVC流化床气化生烟量明显减少,过量空气系数0.6时,生烟量减少到PVC质量的10%左右.提出的HCl析出与生烟机理较好地解释了试验结果,为城市生活垃圾气化熔融技术提供了相关基础数据与污染物生成及控制方法.

In order to develop a low emission municipal solid waste （MSW） fluidized-bed gasification and swirl-flow melting process, a fluidized bed gasifier was designed at the laboratory scale to research the gasification characteristics of PVC, which is widely existed in MSW and brings severe pollution and corrosion in MSW thermal disposal, especially the corrosion by HCI. The experiments were carried out at different excessive air ratios （0.2 ～ 0.8 ） and temperatures （400 ℃～700 ℃ ）. The products from PVC gasification were characterized by using the proximate and ultimate analyzer, gas chromatography analyzer and titration of AgNO3. When the temperature is over 600 ℃ and the excessive air ratio is about 0.4, the conversion of CI to HCl achieves over 95%. While the gasification efficiency reaches 22% ～ 25% and the LHV of product gas is only 2 000 kJ/m^3 ～ 2 300 kJ/m^3. Increasing the temperature or excessive air ratio is an effective way to reduce the yield of smoke. When the temperature is 700 ℃ and the excess air ratio is 0.6,the yield of smoke is decreased to about 10%.Based on the results of experiments, the forming mechanisms of HCl and smoke are proposed and explained.