Molten waste plastic pyrolysis in a vertical falling film reactor and the influence of temperature on the pyrolysis products

doi:10.1016/j.cjche.2017.08.001

Abstract

Abstract: Molten plastics are characterised with high viscosity and low thermal conductivity. Applying falling film pyrolysis reactor to deal with waste plastics can not only improve heat transfer efficiency, but also solve the flow problem. In this work, the pyrolysis process of molten polypropylene (PP) in a vertical falling film reactor is experimentally studied, and the influence of heating temperature on pyrolysis products is discussed. It has been found that with the temperature increases from 550℃ to 625℃, the yield of pyrolysis oil decreases from 74.4 wt% (±2.2 wt%) to 53.5 wt% (±1.3 wt%). The major compositions of the pyrolysis oil are C₉, C₁₂ and C₁₈, and β-scission reactions are predominant. The content of the light fraction C₆-C₁₂ of pyrolysis oil is 69.7 wt%. Compared with other pyrolysis reactors, the yield of oil from vertical falling film pyrolysis reactor is slightly higher than that from tubular reactor, equal to that from rotary kiln reactor, and slightly lower than that in medium fluidised-bed reactor.

Key words: Pyrolysis, Reactor, Molten plastic, Pyrolysis oil, Fractional condensation

摘要： Molten plastics are characterised with high viscosity and low thermal conductivity. Applying falling film pyrolysis reactor to deal with waste plastics can not only improve heat transfer efficiency, but also solve the flow problem. In this work, the pyrolysis process of molten polypropylene (PP) in a vertical falling film reactor is experimentally studied, and the influence of heating temperature on pyrolysis products is discussed. It has been found that with the temperature increases from 550℃ to 625℃, the yield of pyrolysis oil decreases from 74.4 wt% (±2.2 wt%) to 53.5 wt% (±1.3 wt%). The major compositions of the pyrolysis oil are C₉, C₁₂ and C₁₈, and β-scission reactions are predominant. The content of the light fraction C₆-C₁₂ of pyrolysis oil is 69.7 wt%. Compared with other pyrolysis reactors, the yield of oil from vertical falling film pyrolysis reactor is slightly higher than that from tubular reactor, equal to that from rotary kiln reactor, and slightly lower than that in medium fluidised-bed reactor.

关键词: Pyrolysis, Reactor, Molten plastic, Pyrolysis oil, Fractional condensation

Zechen Jin, Dezhen Chen, Lijie Yin, Yuyan Hu, Huangqing Zhu, Liu Hong. Molten waste plastic pyrolysis in a vertical falling film reactor and the influence of temperature on the pyrolysis products[J]. Chin.J.Chem.Eng., 2018, 26(2): 400-406.

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