OCR Text |
Show combustibility test has been mainly applied to the combustion characterization of the bituminous coals used in the preparation of coal-water slurry fuels [1]. This paper will report upon the effort to expand this combustion data base on pulverized bituminous coal to include information on different lignite coals and on various chars. One current drawback with the plane flame furnace combustibility technique is that it can only be conducted on dry, pulverized coal. In order to complement the combustibility method on neat pulverized coal, an ignition test has been established with a second combustor, with which all phases of fuel can be fired. Combustibility test results using this multiphase fuel furnace will also be reported in this paper. The ASTM volatile matter content of a coal is usually used as a measure of the ease of ignition of a pulverized coal [1,2]. It is also known that the ASTM volatile matter does not characterize very well the volatile matter content that is released upon rapid-heating to high temperatures in pyrolysis experiments [9-10]. Comparisons between experimental volatiles yields and those of ASTM proximate volatile matter reveal that upon rapid-heating to high temperatures: (a) as much as 85% more volatiles are released [10] and (b) as much as 70-80% of the original weight of the coal is converted to volatile matter [9]. Because of these results, it became apparent [2] that a new procedure for determining ignition quality could be devised in which pulverized coal was not burned at all, but only its volatiles. Homogeneous combustion would be exploited to evaluate heterogeneous combustion. This simple new standardized test, involving gaseous flames of coal volatiles, was meant to complement those coal ignition/burnout tests in which coal is burned (PSU-FCL-PFF), and not burned (dTGA). They were also meant to attempt to gain a chemical insight into the ignition mechanism of pulverized coal. 22-5 |