Waste Gasification by Thermal Plasma: A Review

This paper proposes an overview of waste-to-energy conversion by gasification processes based on thermal plasma. In the first part, basic aspects of the gasification process have been discussed: chemical reaction in gasification, main reactor configuration, chemical conversion performances, tar content in syngas and performances in function of the design and the operation conditions (temperature, pressure, oxidizing agent.). In the second part of the paper are compared the performances, available in the scientific literature, of various waste gasification processes based on thermal plasma (DC or AC plasma torches) at lab scale versus typical performances of waste autothermal gasification: LHV of the syngas, cold gas efficiency and net electrical efficiency. In the last part, a review has been done on the various torch technologies used for waste gasification by plasma at industrial scale, the major companies on this market and the perspectives of the industrial development of the waste gasification by thermal plasma. The main conclusions are that plasma technology is considered as a highly attractive route for the processing of waste-to-energy and can be easily adapted to the treatment of various wastes (municipal solid wastes, heavy oil, used car tires, medical wastes.). The high enthalpy, the residence time and high temperature in plasma can advantageously improve the conditions for gasification, which are inaccessible in other thermal processes and can allow reaching, due to low tar content in the syngas, better net electrical efficiency than autothermal processes.