Experimental investigation of plasma assisted combustion of low Heating Value biomass with a three phase AC plasma torch

International audienceA wide array of applications exist for mid-range power plasma torches (tens of kW) starting from municipal waste gasification to the synthesis of chemical products. The majority of commercialized plasma torches are working in inert or reductive environments. Recent feasibility study demonstrated the economic profitability of the plasma assisted combustion for the start-up of coal and biomass thermal power plants. In order to prove the technical feasibility of this application, a three phase plasma torch working with consumable graphite electrodes and operating with air at 100 kWe, has been developed. Hereafter, the specifications of this plasma torch are detailed along with a briefing on the early CFD simulation and the main technical challenges encountered. A set of experiments are performed to validate the concept and characterize the torch, first, without combustion, and then, with the injection of a biomass sample. Different feeding rates are also tested. First results showed excellent combustion efficiency. Burned gases are analyzed using gas chromatograph and non-dispersive infrared sensor. In addition, a high speed camera (up to 1 million fps) showed particle behavior inside the plasma and graphite electrode erosion process. The overall results confirmed the technical feasibility of the plasma assisted combustion for the tested sample and the reliability of the developed three phase plasma torch