Pyrolysis Characteristics of Excavated Waste and Generation Mechanism of Gas Products

With the initiatives of Circular Economy, the excavation of landfills provides an important opportunity for waste resource recovery. Currently, the research on the excavated waste mainly focuses on the physical composition, and less studies on excavated waste pyrolysis. Pyrolysis technology can not only reduce the amount of waste, but also obtain tar, pyrolysis gas and char with high calorific value and application characteristics. In this work, the pyrolysis properties of different components of excavated waste were studied, including the thermal characteristics, the distribution of pyrolysis products and the composition of pyrolysis gas. The results show that the pyrolysis activation energy of wood and textile was lower than that of plastics and rubber, and it was easier for the pyrolysis reaction to proceed. In the temperature range of 500-900℃, the pyrolysis gas gradually increased and the tar showed a decreasing trend. Plastic has the highest yield of tar, reaching 74.9%. The pyrolysis gas was determined by Micro GC, and the pattern of gas release during pyrolysis was also monitored. The main composition of pyrolysis gas was H₂, CO, CO₂, CH₄, and C₂-C₃ hydrocarbons. High temperature was more conducive to H2 production. In addition, the pyrolysis properties of excavated waste and raw waste was compared. Based on these findings, pyrolysis of excavated waste provides a possible avenue for municipal solid waste landfill extraction and utilization.