OCR Text |
Show oil meter, primary air meter, exhaust gas temperature, and the main exhaust gases: CO, CO , and 0 . 3. FUEL CHARACTERISTICS Three slurries from three independent sources have been used in these experiments. Their analyses are listed in Table 2. As the analyses show, they are relatively close in dry coal analysis and water composition. The table includes the relevant fuel oil data. For initial experiments, particularly for development of the slurry pumping loop, a site-made slurry was used. A semi-stable slurry was quite easily made using a standard grind coal (obtained by a skimmer downstream of the mill in a power station). Various surfactants were used including some domestic detergents as well as commercial stabilizers. This preparation was used while waiting for delivery of the commercially prepared slurries. It performed without particular problem in the low pressure pumping loop. However, it lacked the bimodal size distribution commonly recommended to aid stability, and contained too large a fraction of particle over 100 microns, both of which caused problems at high pressure. The slurry would pump adequately through a clean line in the high pressure loop but would sediment within minutes when pumping stopped which prevented a re-start without cleaning out the line. Atomization was always poor in the ME atomizers and they usually plugged quickly; the main problem here seems to have been the oversize fraction. This low grade slurry, however, was quite adequate for developing the pumping loops; these pumping problems did not occur with the commercial slurries. All the slurries were delivered in 55 gal drums. Because of timing of the deliveries nearly all the samples were left undisturbed for periods |