Cogeneration Power Plant for Processing Biomass with the Application of Solid Oxide Fuel Cells

Abstract

The relevance of the issues of using low-grade and wet organic fuels is determined by modern energy saving trends. In particular, this applies to the direction of involving low-grade fuels in the fuel energy balance and providing heat and electricity for the areas of decentralized energy supply. The paper deals with the process of high-temperature thermal decomposition of plant biomass waste by a combined pyrolysis-gasification method in a steam-air environment enriched with oxygen using solid oxide fuel cells (SOFC) to generate electricity. High enthalpy and high chemical activity of the gasifying agent allows the process of thermal decomposition to be carried out in an autothermal regime. The high-temperature regime and application of steam-air blast enriched with oxygen provides a high degree of conversion of waste from plant biomass to the combustible components of CO, CH4, H2, the resulting gas mixture. After the generation of electrical energy, the exhaust gases undergo complex purification from combustion products and cogeneration of residual thermal energy. In particular, purification from toxic nitrogen oxides (NOx) occurs, formation of dioxins, furans and other dangerous chlorinated derivatives of compounds is prevented. The potential acid components of the exhaust gases are neutralized. These components affect the kinetics of the process, oxidation-reduction reactions in SOFC and reduce its efficiency, as well as contamination of electrolyte membranes and degradation of electrode materials. The use of gasifying agents can significantly reduce the formation of toxic components in a mixture of combustible gases. The heat energy withdrawn at various sites of the plant is almost completely used for the needs of the cogeneration plant and its units, which allows achieving a total efficiency of at least 86%. The ability of the cogeneration unit to use variable gasifying agents allows to work on various types of solid waste and as a result to have a wide range of applications and operational capabilities.