Mineral and chemical composition of fly ashes deriving from co-combustion of biomass with coal and its application

Introduction Improvement in the range of conventional raw materials balance for electricity production is possible through the use of renewable fuels. Such solutions result of the conditions prevailing in the in the European Union as well as sustainable production and consumption of mineral resources, including energy resources. Furthermore, they must be met conditions in the range environmental protection. Substitution of fossil fuels is usually brought to the use of biomass for power generation processes and heat. According to Regulation of Minister of Management on 14 August 2008 (Dz.U. nr156,poz.969) biomass is a solid or liquid substances of plant and animal, biodegradable, deriving from the products, waste and residue from agricultural production and forestry as well as industry of their products processing, as well as other waste, which is biodegradable waste. According to standard procedures co-combustion of biomass with coal is one of the simplest and cheapest solutions leading to an increase in the share of energy from renewable fuels. Co-combustion of these fuels have a number of advantages and drawbacks. The first include: − possibilities of usage of large amounts of biomass, − emission reducing of carbon dioxide, sulfur dioxide and NOx compared to fossil fuels, − diversification of energy sources, − logistical issues related to the conditions of supply of biomass for energy producer, − reducing the risk to the environment connected with obtaining fossil fuels, − it is important that the combustion process and the distribution of thermal load of the heating surfaces. The main disadvantages of co-combustion are due to technological criteria and the technical and economic. Among them are indicated: − different characteristics of biomass in relation to physical and chemical properties of coal, calorific value, which is lower for biomass per unit volume. The values for biomass use in domestic conditions are at the level 6–20 MJ/kg, − differences in contents of volatile matter in relation to their content in fossil fuels, − significantly higher volatile matter content significantly affects the ignition conditions and the process of co-combustion, − different softening and melting temperatures of ashes, which are connected with different chemical and mineral composition of biomass compared to coal.