ELECTRIC POWER GENERATION BASED ON COAL SLURRY ELECTROLYSIS WITH SUBSEQUENT USAGE OF PRODUCED HYDROGEN IN FUEL CELLS

摘要

Current mining practice allows extracting slightly over one-half of commercial coal reserves, whereas the other half remains underground due to technological and technical reasons. Only 10 to 15 % of the coal extracted to the surface is used in electric power generation. The remaining part is lost with coal mining waste, coal improvement, and in ash dumps in the form of non-combusted carbon. But the major portion of energy extracted from coal is dissipated to no effect to the environment with combustion and condensation products because the efficiency of TPPs does not exceed 33 to 35 %. A known solution to this problem is creating and utilizing power installations with coal-fired fuel cells (FC). As a rule, coal is first gasified, and then the producer gas is fed to fuel cells. However, carbon oxide, which is formed by partial oxidation of coal and hydrocarbons, is an extremely unstable compound that recombines, under specific conditions, to solid carbon, i.e. fuel soot, which clogs the FC pores and damages the electrochemical equipment. Soot formation can be eliminated by increasing the gasification pressure to 15-20 MPa, and the temperature to 200-250℃. In so doing, shifting the reaction of interaction of carbon with water to formation of decomposition-resistant hydrogen and carbon dioxide is effected by coal slurry electrolysis. Electric current reduces the carbon activation energy, making it possible to run the gasification process at relatively low temperatures. Carbon dioxide is readily absorbed from the mixture with alkali solutions. Having separated carbon dioxide, pure hydrogen is fed to the fuel cell.