OCR Text |
Show coalfield in Nova Scotia is particularly amenable to this combination of processes and shows promise of good yields with mineral matter in the 1.5 to 3 percent range and with about two-thirds of the original sulphur removed. Several estimates have indicated that deposition of slag on the tubes of boilers tightly designed for oil firing would contribute very substantially to boiler derating which could be as much as 50 percent when coal is used as fuel. The site chosen for preliminary tests was again the generating station at Chatham, New Brunswick since it has two boilers originally designed to burn coal but recently adapted to burn oil, one front-wall fired and one tangentially fired, and of 12 and 23 MW(e) capacity respectively. The results obtained at Chatham, where coal-liquid-mixture burners will replace oil nozzles, will yield, at a small utility scale, virtually all the data required to assess burners and fuel without risk of damaging a bigger furnace or of seriously interrupting electricity supply. Objectives of Present Program The ultimate objective of the coal-liquid-mixture program is to derive enough data concerning the fuels and how to burn them that potential users will be able to make decisions to replace oil, based on economics and without technical risk. An essential sub-objective is the establishment of a quality-cost-price relationship. Obviously it costs more to prepare a high quality (i.e. low sulphur, low ash) mixture than a low quality one. Research into the application of oil agglomeration to coal-oil-water mixtures has indicated the costs in terms of light oil addition for various levels of rejection of mineral matter including sulphur. Depending on the fineness of grind and mineral content needed, light oil requirements may vary from 1 to 5 percent of coal weight. For coal-water mixtures, conventional cleaning applied to the highest quality coal can reduce mineral 12-11 |