Abstract
The author Classified the combuston of solid fuel from comparing the burning velocity into three types of (i) surface combustion, (ii) decomposing com-bustion and (iii) evaporating combustion.
Coke, anthracite, charcoal etc. have less volatile matter and their combustion be-longs to type (i).They are not pure carbons but rather a sort of carbon compounds nevertheless their initial reaction could be considered as one of the combustion of solid carbon.
In the decomposing combustion of solid fuel such as coal, lignite, wood etc., they are dehydrated at the initial stage, then slowly oxidized and finally ignited.They are thermally decomposed at the ignition point, then combustion of gases formed occurs accompanying the combustion of solid fuel material.These combustions are situated between those of solid carbon and hydrocarbon but the initial reactions may be simillar to that of higher hydrocarbon. Paraffin gives an evaporating combustion which is characteristic to the combustion of hydrocarbon.
The burning velocity of solid fuel is controlled by the rate of chemical reaction at low temperature and by the diffusion velocity of air at high temperature.These results have been showed by the other researches, but at higher temperature the greater parts of solid fuel must be changed to solid carbon and at the same time the graphitization of amorphous carbon must occur, so the mechanism of combustion at higher temperature must be entirely different from the one at low temperature and the burning velocity is again controlled by the reaction rate.The reaction has a tendency to be disturbed by the poisonous action of combustion products at more higher temperature.
