High-efficiency Dechlorination of Waste by Selective Injection of Microwave Energy into Chemical Bonding between Chlorine and Hydrocarbon

本研究探讨了微波对垃圾中有机氯化合物的脱氯作用，认为微波对有机氯的选择性激发是有前景的。本文以聚氯乙烯（PVC）作为有机氯化合物的样品。为获得其热分解性能，对其进行了热重分析。分析结果表明，热分解反应为两步反应，第一步反应发生在483 ~ 573 K范围内。认为第一步主要是由脱氯反应引起的。研究了微波辐照和常规加热对PVC脱氯性能的影响。在463 ~ 493 K的恒温范围内测定了脱氯比。结果表明，在463 ~ 483 K范围内，微波脱氯反应速率和脱氯比均大于常规加热脱氯反应。采用具有微波透明性的玻璃微珠流化反应器作为实验设备，实现了聚氯乙烯的均匀微波辐照。考察了聚合度、反应器初始温度、微波辐照强度和气速对脱氯比和床层温度分布的影响。当初始反应器温度小于334 K时，脱氯反应未被确认。这就是为什么PVC在较低温度下的介电损耗太小而不能吸收微波能量的原因。而当初始温度大于334 K时，床层温度在450 K以上迅速升高，脱氯反应迅速。聚氯乙烯聚合度越小，在600 W微波下脱氯率越高。而在800w条件下，脱氯率与聚合度无关。

In this research work, dechlorination of organochlorine compound in waste by using microwave was discussed, as selective excitation of organochlorine by microwave was prospective. Here, Polyvinyl chloride(PVC) was used as sample of organochlorine compound. To obtain its thermal decomposition property, thermogravimetric analysis was carried out. From the results of the analysis, it was found that the thermal decomposition reaction was two-step and the first step took place in the range 483-573 K. It is consider that the first step is mainly caused by dechlorination reaction.Difference between dechlorination properties of PVC with microwave irradiation and with conventional heating was investigated. Dechlorination ratio was measured under several constant temperatures hi the range 463-493 K. It was indicated that both reaction rate and ratio of dechlorination with microwave was greater than those with conventional heating in the range 463-483 K.For uniform microwave irradiation of PVC, fluidized bed reactor using glass beads which had microwave transparency was applied to test equipment. The effect of degree of polymerization, initial reactor temperature, irradiation intensity of microwave and gas velocity on dechlorination ratio and temperature profile of bed was investigated. When the initial reactor temperature was less than 334 K, dechlorination reaction was not confirmed. That is the reason why the dielectric loss of PVC at the lower temperature is too small to absorb microwave energy. On the contrary, rapid rise of temperature in bed and dechlorination reaction was observed over 450 K when initial temperature was more than 334 K. The smaller degree of polymerization of PVC was, the higher dechlorination ratio was observed at 600 W of microwave. However, the dechlorination ratio was independent of the degree of polymerization under condition of 800 W.