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Show IDEAL COMBUSTION OF SOLID FUELS S. C. Ling and H. P. Pao The Catholic University of America Washington. D.C. 20064 ABSTRACT Paper No. 4 Unlike the unstable. runaway. combustion of micro-fuel particles, solid fuel in the reconstituted form of a specifically shaped charge was found to have stable and ideal combustion characteristics suitable for the automatic control of combustion rate and temperature. Consequently. most environmental and operational problems associated with the atomized-combustion process can be eliminated. The shaped-charge fuel is applicable for both large power generation as well as for small home heating. INTRODUCTION Historically, solid fuel was burnt mainly by the flat-bed combustion process. In the past two decades, solid fuel was replaced by liquid fue}. because liquid fuel is less labor intensive and is cleaner in operation. The liquid is burnt by the spraying technique through a high-speed nozzle to atomize the fuel. In recent years, as liquid fuel became too costly. the power plants were modified for both liquid and powdered solid-fuel combustion, retaining the spraying technique which was originally designed for the liquid fuel. For horne heating, liquid fuel is still in wide use, mainly due to the handling and pollution problems of solid fuel. Fundamentally, the combustion of both fine liquid and solid fuel particles is an unstable runaway form of combustion which takes place within 10 milliseconds1. It is next to impossible to control the reaction rate. The resulting high temperature of combustion promotes excessive production of CO. NO x , and SO x gases, and the production of corrosive and coating micro-flyash. These are key operational and environmental problems that have no easy solutions. Hence, it is imperative that we should start to search for a more fundamental solution to the combustion problem. Ironically, the ideal method for the combustion of solid fuels is not new; the burning of shaped-charge fuel used in a space rocket or a bazooka, and the ancient burning of reconstituted-coal briquette with venting holes are typical examples. Coal briquette with holes is extensively used in the Far East for home cooking and heating. For the new method of burning coal, it is proposed that pulverized coal be mixed with lime, clay, and other chemical additives and formed |
