聚乙烯在连续给料外热式回转窑内的热解研究

Study on Polyethylene Pyrolysis in Continuous-Feeding External-heating Rotary Kiln

在连续给料外热式回转窑试验台上,以聚乙烯为试验物料进行了热解产气特性、质量平衡以及能量净收益的试验研究。产气特性试验结果表明:温度一定、延长停留时间,或者停留时间一定、提高温度都会促进热解进行,不仅可以提高热解的产气份额,而且还可以提高热解气体的热值。在选定热解停留时间为31.58min、温度为500℃和600℃的2种工况下进行了质量平衡试验,并对此进行了热解前后总热值对比和热解能量的净收益率分析,结果表明:500℃的热解吸热量是其热解产物总热值的1.18%;600℃的热解吸热量是其热解产物总热值的6.34%。与热解温度为600℃时相比,500℃的热解吸热量仅是600℃的18.39%,但是,500℃的热解效率却是600℃的38.23%;500℃热解能量的净收益率是600℃的1.06倍。如果对废弃聚乙烯采用热解-焚烧技术处理,那么,其中热解部分选择500℃作为热解温度是合理可行的。

By the continuous-feeding external-heating rotary kiln, the experimental studies on the gas yield characteristics, mass balance and net energy income of the polyethylene pyrolysis were performed. Through the gas yield characteristics experiments, it was concluded that longer residence time and higher pyrolysis temperature are advantageous to improving the gas yield percentage and the heat value of the pyrolysis gas. In the mass balance experiments, the residence time of 31.58min and pyrolysis temperatures of 500℃ and 600℃ were employed. Based on these experiments, the total heat values before and after pyrolysis were compared, and the net pyrolysis energy income ratio was analyzed. It indicates that the ratio of pyrolysis heat absorption capacity to total heat value of pyrolysis product at 500℃ is 1.18%, while that at 600℃ is 6.34%. Although the pyrolysis heat absorption capacity at 500℃ is only 18.39% of that at 600℃, the pyrolysis efficiency at 500~C is 38.23% of that at 600℃, and the net pyrolysis energy income ratio at 500℃ is as 1.06 times as that at 600℃. If the waste polyethylene is treated by pyrolysis-incineration technology, it is reasonable and feasible that 500℃ is adopted as the operation temperature for the pyrolysis stage.