OCR Text |
Show from oil firing in the period 1977/78. With reliable operation demonstrated in over 25,000 operating hours the GP Worsley furnace range is being extended and applied to other products. A 15 MW furnace to supply hot gas for clay drying has been operated successfully at Ketton Cement, since 1980. Subsequently GPW have supplied an 18 MW coal fired furnace to Denmark for chalk drying, a 7.5 MW furnace to Amey Roadstone for stone drying and heating, and furnaces of 2 MW, 6 MW and two of 10 MW for coal drying. Fbc hot gas furnaces are also available from Energy Equipment, who have supplied units of 9 MW and 16 MW for grass drying. For products dried by clean hot gas, currently produced by firing natural gas or distillate oil, it is necessary to use a coal-fired air heater. A design incorporating a ceramic heat exchanger immersed in the bed is being developed by the NCB in collaboration with Encomech Engineering Services. Following the successful operation of a 200 kW prototype a 1.8 MW unit is being installed at the Bass Maltings, Mirfield, Yorkshire. To convert most industrial thermal processes, other than drying, to coal will inevitably require some redesign. An example of this is a prototype fbc gypsum calciner, which has demonstrated a substantial improvement in thermal efficiency in comparison with conventional designs. A larger commercial version is now being designed. 2.2.4 Electricity generation by fbc In the UK 70% of current coal output is used for electricity generation in pulverised fuel fired power stations. Although it is expected that nuclear power will provide an increasing proportion of the base load electricity supply, it is expected that new coal fired stations will be required to provide mid-merit and peak load supplies. Some of these new units may well be of a smaller scale than current power stations, located near cities so that the reject heat can be utilised. Fbc will provide an environmentally acceptable combustion system for this new generation of installations. 20-19 |