| OCR Text |
Show experiments had established the ignition temperature for a test fuel, the furnace would be preheated to that target temperature, the gas burner shut off, removed, its entry port plugged, and the desired steady-state pulverized coal feed established. Typical plane flame furnace ignition temperatures for the coals studied were in the 1000-1100°C range. The pulverized coal was pneumatically delivered to the furnace, after being metered via a commercially available vibrating screw-feeder system, at a rate of 8 pounds/hour, or 0.11 x 10 Btu/hour. The maximum deviation in the feed rate from the mean value during a given run was ± 5%. The coal/air stoichiometry was set at + 25% excess air for all the tests to be reported. Plane flame furnace combustion tests were conducted for the six different neat coals that have been prepared into coal-water slurries 6-9 and test burned to date, along with one very low volatile (devolati- 10 lized) bituminous coal that had been previously studied at the PSU-FCL. Samples of the coals were obtained from the Coal Sample and Data Bank at The Pennsylvania State University Coal Research Section. The proximate analyses of all 7 of the coals burned at the PSU-FCL are listed in Table IV as a function of decreasing volatile matter content. The first six neat coals have been labelled according to the names given them in the publications in which their respective coal-water combustion tests were reported. " The last coal studied, that labeled "JPL-PSU-FCL," consists of Pittsburgh #8 coal that had been selectively devolatilized via a patented Jet Propulsion Laboratory (JPL) sulfur-removal process known as chlorino-lysis/ hydrodesulfurization. In this chemical process, only the volatile matter and the sulfur content are changed (reduced). Since sulfur is not expected to play a major role in coal particle combustibility phenomena, it can be rather readily assumed that a direct measure of the role of volatile matter in the coal ignition event can be evaluated by burning the aforementioned pair of devolatilized coals, i.e., raw (36% volatile matter) and JPL-devolatilized Pittsburgh //8 (6.5% volatile matter). It should be noted that Pittsburgh #8 coal represents 32% of the total amount of domestic coal selected by the U.S.D.O.E. for use in coal-water slurry combustion, the neat coals were pulverized to a mass mean diameter of 53 microns. 17-12 |
