Coal combustion is a source of multiple pollutions:sulphur and nitrogen oxides, particles, mercury, cadmium, arsenicum, etc. It is difficult to remove contaminants from coal before burnning. Coal washing may create just an additional problem. Some modern technologies to control polutions still can not bring them to the environmentally save level.
Waste Derived fuels ( RDF/SRF) are produced by conversion of MSW to fuel by dehydrating and shredding the waste at the dedicated Mechanical Biological Treatment facility. The resulting product, comprised of combustible components of MSW, is a quality alternative fuel to fossil fuels such as coal. Non-combustible materials of MSW such as glass and metals are recycled.
Currently Waste Derived Fuels (WDF) are classified in categories of Refuse Derived Fuels (RDF) and Solid Recovered Fuels (SRF). The last one is more refined product, includes paper, plastics, wood, textile and has higher calorific value than RDF.
While WDF is a quality product, the environmental issues related to its utilization by means of combustion still remain. Thus, usage of modern alternative fuels requires efficient alternative technology such as pyrolysis.Energy of the pyrolysis products can be recovered in a waste-heat boiler with further use of generated steam for electricity production and/or for district heating repeating cycle used in coal power plant.
In year 2004 Institute of Applied Energy (Tokyo) performed an analysis of stoker incinerator and pyrolysis plants operating under the same conditions. The analysis revealed that at any production scale the pyrolysis process with a steam turbine has economic and performance advantages.RDF / SRF pyrolysis is a solution for partial conversion (cogeneration) or complete conversion of coal -fired power plants.