Objectif To provide 90 % of total space heating and hot water requirements from pelletized refuse derived fuel (RDF) to at least 2,000 homes, the RDF being prepared from domestic waste. Total energy savings will be 3,300 TOE/y.Two new wet-back boilers with automatic de-ashing grates were installed alongside the existing fixed grate boiler. The boilers were modified to accommodate the de-ashing grates. The de-ashing facility was required for when the plant was fed with high-ash producing RDF.The grates comprised of four longitudinal sections, each one independently pivoted.During normal de-ashing operations the section was sequentially tipped to deposit a quarter of the firebed. The grate sections were cooled by pumping water through their hollow spindles.The new boilers were first fired in 1983 and initially they were to run on coal, eventually transferring to a coal/RDF mixture, or pure RDF. Immediately the new boilers were fired, problems arose with the cooling system for the automatic grates. The operation of the de-ashing grates also resulted in the emission of black smoke. This was due to insufficient turbulence within the combustion chamber. A compressed air-feed system failed to remedy the smoke problem. The most serious early problem with the boilers was the excessive erosion of the smoke tubes due to grit transportation. Protective ferrules were constructed to protect the smoke tubes where the erosion was most severe.The early and continuing problems limited the opportunities of burning RDF. However, when trials were carried out the RDF bunker feed screw itself suffered repeated jamming. The several test burns on RDF also resulted in a clinkering problem within the ash silos.Another problem was the inadequate ash control equipment. Dust emissions being excessive and unacceptable during normal operation. The addition of a wet scrubber after the high efficiency cyclone to clean the discharge air proved unsuccessful.Evidence of overheating was apparent in the two boilers, and excessive bulging had to be cut out and replaced. Cracking at the rear of the older fixed grate boiler was also discovered and to avoid catastrophic failure a decision was made to close down allthree boilers. Progress in identifying the causes of the boiler problems was halted due to the bankruptcy of the engineering company. However, the failure of the project can be attributed to boiler design faults and not to problems arising from the burning of RDF. The objective of the project, to provide space heating and hot water to 2,000 homes through the combustion of RDF, was not achieved as the plant was never fully commissioned. The plant is currently burning coal, but at less than full capacity. The tipping grates are being operated manually.The project features the construction of a 400 m2 extension to an existing 200 m2 boiler house and the installation of two new boilers adapted to cope with the high ash content of RDF. They have an automatic de-ashing grate and mechanism for removing ashes without depressurising. The RDF pellets are 18 mm in dia. 25-50 mm in length 600 kg/m3 in apparent density and 15 MJ/kg in calorific value.The monitoring programme includes RDF analysis, ash characterisation and detailed recording of plant operation. Programme(s) ENG-ENALT 1C - Programme (EEC) of financial support for projects to exploit alternative energy sources, 1979-1984 Thème(s) 1.8 - PRODUCTION AND USE OF REFUSE DERIVED FUEL (RDF) Appel à propositions Data not available Régime de financement DEM - Demonstration contracts Coordinateur CITY OF NEWCASTLE UPON TYNE Contribution de l’UE Aucune donnée Adresse CIVIC CENTRE BARRAS BRIDGE NE99 2BM UPON TYNE NEWCASTLE Royaume-Uni Voir sur la carte Coût total Aucune donnée
