Application of CaO-Decorated Iron Ore for Inhibiting Chlorobenzene during In Situ Gasification Chemical Looping Combustion of Plastic Waste
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- 作者：Jinxing Wang ; Haibo Zhao
- 刊名：Energy & Fuels
- 出版年：2016
- 出版时间：July 21, 2016
- 年：2016
- 卷：30
- 期：7
- 页码：5999-6008
- 全文大小：563K
- 年卷期：0
- ISSN：1520-5029
文摘
Plastic waste has been considered as a renewable energy source, because of its high calorific value. Chemical looping combustion (CLC), with the characteristic of inherent CO2 separation, is a promising alternative for translating plastic wastes into energy with potential to drastically suppress the generation of PCDD/Fs, since it provides an O2-free combustion pattern to inhibit the de novo synthesis of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs). However, due to the existence of much chlorine element in plastic wastes, the generation of chlorobenzene during the CLC processes should be seriously addressed. CaO decoration to oxygen carrier (OC) has been identified as an effective in situ dechlorination route during the CLC processes. In this paper, an inexpensive material, natural iron ore, was considered as the OC. First, the CLC tests of HCl-containing syngas were carried out in a laboratory-scale fluidized bed to compare the difference of the decoration methods (wet impregnation method and ultrasonic impregnation method) and to determine the optimal CaO loading as well as CLC operational parameters. It was found that the ultrasonic impregnation can attain a higher dechlorination efficiency for the type of relatively dense OC material, i.e., natural iron ore. Then, the in situ gasification chemical looping combustion (iG-CLC) experiments of plastic wastes were conducted in the same reactor and the effect of supply oxygen to fuel ratio on combustion efficiency was investigated. Increasing the supply oxygen to fuel ratio can obviously improve combustion efficiency, and the adverse effect of CaO decoration on combustion efficiency can be obviously mitigated when the ratio of supply oxygen to fuel reaches 2.5. Lastly, the stability of CaO-decorated iron ore was evaluated through 10 continuous cyclic redox tests. The organic compounds, including chlorobenzene, were measured via gas chromatography–mass spectrometry (GC-MS). The combustion efficiency was well-maintained during the cyclic redox process and the emission of chlorobenzene was significantly inhibited in the iG-CLC processes. Overall, these results provide sound evidence for controlling chlorobenzene during the utilization processes of plastic waste.