PLASMA STEAM-AIR CONVERSION OF SOLID BIOMASS AND THE PROBLEM OF EQUILIBRIUM ASSUMPTION IN THE GASIFICATION PROCESS

The acceptability of the approximation of the equilibrium state of plasma if it is used in gasification processes is discussed. The development of technologies for converting solid biomass as an available raw material for distributed electricity generation in Ukraine is carried out to obtain both energy and chemical products. The use of biomass gasification technologies and direct conversion of fuel gas energy into electricity in solid oxide fuel cells allows achieving electrical efficiency of power plants of 42 % or more. Plasma torches are used to produce hydrogen-rich gas with low content of high-molecular compounds, as well as to achieve operating gas temperatures before cells mentioned. The conversion of wood coal, wood waste, and walnut shells was studied at the plasma steam-air gasification unit. The use of a steam plasma torch for steam reforming of volatiles in the pyrolysis zone of an air-gas generator leads to the H2/CO molar ratio and H2 yield increase, as well as to the equivalence ratio and N2 concentration decrease in all cases of the selected biomass types. It was found that the yield of pure hydrogen could be increased by adding water shift reactors and membrane hydrogen separation to the existing plant. The production of pure H2 is 0.6 Nm3/h, the cold gas efficiency of H2 production is 47.7 %, and the electricity consumption is 27.75 kWh/kg of H2. Due to plasma steam-air gasification of solid biomass and CO conversion, the electricity consumption for H2 production will be 50.8 % less than the electricity consumption for water electrolysis. It is shown that compared to the latter case, the cost of H2 production by converting solid biomass, taking into account the costs of electricity, biomass, and water in Ukraine, is 39–44 % lower than the cost of hydrogen obtained by water electrolysis. Bibl. 52, Fig. 1, Tab. 9.