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

鉴于微波选择性激发有机氯化合物的前景，本研究探讨了利用微波对有机氯化合物进行脱氯处理。采用聚氯乙烯(PVC)作为有机氯化合物的样品。为了解其热分解性能，对其进行了热重分析。分析结果表明，在483~573K温度范围内，聚氯乙烯的热分解反应为两步反应，第一步反应主要由脱氯反应引起，考察了微波辐射和常规加热对聚氯乙烯脱氯性能的影响。在463~493K温度范围内，测定了几种恒温条件下的脱氯率，结果表明，在463~483K温度范围内，微波加热的反应速率和脱氯率均大于常规加热的反应速率和脱氯率。为使聚氯乙烯得到均匀的微波辐照，试验装置采用了具有微波透明性的玻璃微珠流化床反应器。考察了聚合度、反应器初始温度、微波辐射强度和气速对脱氯率和床层温度分布的影响。当反应器初始温度低于334K时，脱氯反应不确定。这就是为什么聚氯乙烯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。相反，当初始温度大于334K时，在450K以上可以观察到床层温度的快速升高和脱氯反应，聚合度越小的PVC在600W微波下的脱氯率越高。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.