预脱氯处理PVC残渣和平朔煤共热解的协同效应研究

Synergistic effect of co-pyrolysis of pre-dechlorination treated PVC residue and Pingshuo coal

  • 摘要: 热解是煤炭清洁高效利用的有效途径,也是处理废旧塑料高效转化的重要方式。本文针对无害化处理困难的含氯塑料,以聚氯乙烯(PVC)和平朔煤为研究对象,提出将PVC先经预热处理脱除大部分氯,然后将预处理后的PVC残渣与煤进行共热解,并利用气相色谱(GC)、模拟蒸馏、GC-MS、元素分析、红外光谱及拉曼光谱等对热解产生的气体、焦油以及半焦的组成和性质进行分析表征。结果表明,预脱氯处理后的PVC和平朔煤的共热解过程存在协同效应,共热解对半焦和焦油的形成具有明显的正协同作用,焦油产率实验值比理论计算值最大高3.35%;而对热解水和气体的形成产生负协同作用,其中,CH4产率下降最多,即出现最强的负协同效应;共热解使焦油中轻质焦油含量提高,其中,萘类物质含量显著增加,沥青减少,当预脱氯处理PVC添加量为10%时,轻质焦油含量比理论计算值提高5个百分点。此外,共热解半焦表面更为光滑,结构变得更加有序,石墨化度提高。

     

    Abstract: Pyrolysis is an effective way for clean and efficient use of coal, as well as an important way for the efficient conversion of waste plastics. Polyvinyl chloride (PVC) and Pingshuo (PS) coal were used in this research object. A two-step treatment scheme was proposed for chlorine-containing plastics that are difficult to be treated harmlessly. The PVC was preheated to remove most of the chlorine, and then the pretreated PVC residue (DPVC) and coal were co-pyrolyzed. GC, simulated distillation, GC-MS, elemental analysis, FT-IR and Raman spectroscopy were used to analyze and characterize the composition and properties of pyrolysis gas, tar and char. The results showed that the co-pyrolysis process of DPVC and PS coal has a synergistic effect, and the co-pyrolysis has an obvious positive synergistic effect on the formation of char and tar. The experimental value of tar yield is higher than theoretical calculation and the maximum increasing value is 3.35%. There is a negative synergistic effect on the formation of pyrolysis water and gas, in which CH4 has the largest decrease in yield, meaning the strongest negative synergy. Co-pyrolysis increases the content of light tar, significantly increases the content of naphthalenes, and reduces the asphalt. When the DPVC addition was 10%, the content of light tar increases by 5 percentage points over the theoretical calculation value. In addition, the co-pyrolysis char surface is smoother, the structure becomes more orderly, and the graphitization degree increases.

     

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