Investigation of the behavior of the mineral matter of acid composition in high temperature combustion of coal

The main factor determining vaporization of the mineral matter of fuel is temperature, however the effect of this factor varies appreciably with temperature. At T < 2000 to 2200/sup 0/K, the amount of condensed phase (slag melt) becomes less than the amount of the initial ash by a small quantity, corresponding to the vaporization of compounds of potassium, sulfur and iron. Appreciable further decrease in the amount of condensed phase, associated with vaporization of SiO/sub 2/, starts at T approximately 2400 to 2500/sup 0/K and continues up to T approximately 3000/sup 0/K. Increase in pressure, other conditions being equal, reduces vaporization of the mineral matter, correspondingly the amount of condensed phase increases. Other conditions being equal, an increase in oxygen concentration in the oxidizer and change from shortage to excess of oxidizer decrease vaporization of the mineral part. This leads to a corresponding increase in the amount of the condensed phase. Under actual operational conditions of combustion plant with liquid slag removal, for which conditions T < 2200/sup 0/K, p = 0.1 MPa and (O/sub 2/) = 21% are always maintained, we do not expect any appreciable vaporization of SiO/sub 2/. Relatively strong vaporization of SiO/sub 2/ can take placemore » only in special high temperature combustion chambers operating at a pressure of several atmospheres and at T approximately 2800/sup 0/K. However, even in this limiting case the vaporized mineral matter will not exceed 30 to 40%.« less