Zhao Rongfang, Ye Shufeng, Xie Yusheng, Chen Yunfa
Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100080, China.
Huan Jing Ke Xue. 2003 Sep;24(5):28-33.
The co-pyrolysis processes of different proportions of coking-coal, plastic, metallurgical dust (MD) were investigated using thermal analyzer (Setaram Labsys) under a neutral atmosphere of N2 at the sweep rate of 30 mL/min, the linear heating rate and the final pyrolysis temperature were 5 degrees C/min and 1000 degrees C respectively in this study. The experimental results indicated that both the pyrolysis process of coking-coal and that of plastic were radical mechanism. In other word, within the relatively lower temperature range, a large amount of radicals were generated during their pyrolysis processes and stabilized through the intra-radical rearrangement reactions or inter-radical combination reactions. This means that sulfur containing in coal and plastic tends to formed gaseous sulfides, such as H2S, COS, CS2, etc. When co-existing with MD, these sulfides will react with metal oxides containing in MD to form metal sulfide with high stability and the cleaner coke oven gas (COG) were obtained. Within higher temperature interval of 500 degrees C-1000 degrees C, some of the gaseous products after pyrolysis (e.g. H2, CO and C) reinforce the reduction atmosphere that the coking reaction system needs and accelerate the reduction of metal oxides in MD and gasification of metal, which were conductive to the effective removal of sulfur in coke. Therefore, it is definitely feasible to adding waste plastic and MD into coking-coal to remove the sulfur in COG and coke simultaneously.
使用热分析仪（Setaram Labsys）在氮气中性气氛下，以30 mL/min的吹扫速率，研究了不同比例的焦煤、塑料、冶金粉尘（MD）的共热解过程。本研究中线性升温速率为5℃/min，最终热解温度为1000℃。实验结果表明，焦煤和塑料的热解过程均为自由基机理。换句话说，在相对较低的温度范围内，它们热解过程中会产生大量自由基，并通过自由基内重排反应或自由基间结合反应而稳定下来。这意味着煤和塑料中的硫倾向于形成气态硫化物，如H2S、COS、CS2等。当与MD共存时，这些硫化物会与MD中含有的金属氧化物反应，形成高稳定性的金属硫化物，并获得更清洁的焦炉煤气（COG）。在500℃ - 1000℃的较高温度区间内，热解后的一些气态产物（如H2、CO和C）强化了炼焦反应体系所需的还原气氛，加速了MD中金属氧化物的还原和金属的气化，有利于焦炭中硫的有效脱除。因此，将废塑料和MD添加到焦煤中同时脱除COG和焦炭中的硫绝对是可行的。
