A New Plasma Electro-Burner Concept for Biomass and Waste Combustion

Raw biomass resources and many wastes are composed of poor-LHV organic matter (LHV <20 MJ/kg). Their use as renewable fuels for heat or power generation is challenging, particularly when they are in solid form. Indeed, their combustion in air is critical and it is not possible to build autonomous burners independently of external conditions without assistance. Three main options are currently studied: (i) the co-combustion, in which the poor-LHV fuel flame is supported thanks to an additional rich fuel, (ii) the oxy-combustion (iii) the electro-combustion, consisting in the generation of thermal plasma for activating and assisting the combustion. This last option is highly interesting because it only requires electricity (having low carbon content if renewable electricity). Depending on the nature of the feedstock, the electric power of the plasma does not exceed 1–5% of the flame power. Most plasma electro-burners technologies today on the market use DC plasma torches. These technologies suffer from many drawbacks among which: limited electrodes lifetime, poor reliability, important water cooling needs, need of AC/DC transformers, etc. leading to high CAPEX and OPEX. With the objective to go over these limits and reduce OPEX and CAPEX while increasing reliability, the Center PERSEE MINES-ParisTech has been working in the development of an original three-phase AC plasma technology to be integrated in a plasma electro-burner. This paper presents the main achievements on the plasma technology with a special focus on the limitation of electrodes erosion thanks to an active thermochemical gas sheathing.