Objetivo The aim of the action is to increase the boiler efficiency by reducing unburnt content in bottom ash in Unit 3 of Megalopolis Power Plant by installing a dry bottom ash postcombustor to strongly reduce the unburnt material still present : this post combustion will take place directly under the furnace in the stainless steel extraction belt by creating a high reactivity thanks to the high temperature and the oxidizing atmosphere.The high temperature is reached by properly insulating the zone under consideration and controlling the quantity of the incoming air (enough to have a zone reach in oxygen but not too much so as to avoid excessive cooling); at the same time the belt velocity will be controlled to have enough residence time for the ash to burn : the expected result is to reduce the unburnt material in bottom ash to 40% of the present value.The following results are expected from the application of the system :- boiler efficiency improvement of around 1.4% with the consequence of increasing the power generation during full load periods and reducing the fuel consumption during the reduced load periods- strong reduction of the water requirement from the power station, by the complete elimination of any water need from the system- strong reduction in the environmental pollution by complete elimination of any water discharge from the bottom ash system- reduction in the amount of solid byproduct (bottom ash) thanks to the reduction of water content and of the unburned carbon content- increase of the potential of ash reusing in the building industry thanks to the reduction in the unburned carbon- strong improvement of the bottom ash system reliability (presently low in Megalopolis)The project will be implemented in the Unit 3 of Megalopolis Power Station. The bottom ash is, in Megalopolis, presently extracted by means of a conventional Submerged Chain Conveyor (SCC), using water for ash cooldown. The innovative postcombuster where the described process is implemented.The process consists in using an innovative and patented technology of steel belt conveyor as a postcombustor by creating a hot zone under the boiler (inserting appropriate insulating surfaces, controlling the amount of postcombustion air and regulating the ash. The process is completed by cooling down the ash; the ash cooldown takes place in a separate section before ash unloading form the belt and is then completed by air in a direct contact cooler. At this point, a conventional ash handling system can be used to convey the ash to the final silo.The following subsystems can be identified :- postcombustion zone : this postcombustion zone is located underneath the furnace with a 3 meters extension towards the ash discharge to allow postcombustion of last ash particles fallen from the furnace.- cooling section : at the exit of the combustion zone, a first ash cooling is realized by cold air in countercurrent with the ash bed; in addition, a great contribution to the cooling is here obtained by radiation from the ash (hot) to the conveyor case (cold); the cooling of the casing is boosted by fins located in the top of the case itself.- ash conditioning/handling section : at the cooler discharge, the ash is discharged to an ash conditioner, where, at the same time, the required final ash humidity and temperature are achieved.- control system : The handling system is completed with a completely automatic control system. The control system is composed by the following subsystems :- Motor Control Center- System Supervision and Control System Ámbito científico engineering and technologyelectrical engineering, electronic engineering, information engineeringelectronic engineeringcontrol systemsnatural sciencesearth and related environmental sciencesenvironmental sciencespollutionengineering and technologyenvironmental engineeringenergy and fuels Programa(s) FP4-NNE-THERMIE C - Specific programme for research and technological development, including demonstration in the field of non-nuclear energy, 1994-1998 Tema(s) 5 - SOLID FUELS Convocatoria de propuestas Data not available Régimen de financiación DEM - Demonstration contracts Coordinador PUBLIC POWER CORPORATION (PPC) Aportación de la UE Sin datos Dirección HEP DEV. DEPT 56-58 AGISIALOU STR. 10436 Athens Grecia Ver en el mapa Coste total Sin datos
