OCR Text |
Show quantitative result derived from these experiments was also and initial measure of the amount of propane required to atomize a unit of CWS. All tests but one were made with the pulse combustor in the mode shown in Fig. 6, with frequencies of 20-30 hertz and pressure rises of 20-30 psi. The one exception was a test in the aerovalve mode (Fig. 5), with a frequency of around 200 hertz and pressure amplitudes of near 5 psi. Tests were carried out using both injectors and several tailpieces. In a successful run a stable slurry flame was established in the can combustor. Combustion products included very fine ash or partially burned particles, and unfortunately, a small fraction of large particles. These large coal agglomerates traveled at high velocity through the can combustor and out, and some were observed to be still wet upon exiting the combustor. After initial problems with plugging at the injector tip it was found that similar atomization quality was obtained in two radically different tailpieces and with either of the two slurry injectors, so long as the combustor was run in the closed mode. Typical run conditions were a propane flow of .28 gis, an air flow of 4.3 gls to the pulse combustor, .slurry flow of 2 gis, and air to the slurry combustor at 13 g/s. This is an input of 36 kJ of propane to atomize 100 kJ of CWS. This is clea~ly not an optimum value, but the successful tests do show the potential of the method. In the aerovalve mode the slurry was not successfully atomized, but filled the tailpiece and eventually caused the pulse combustor to stall due to obstruction of the tailpiece. The motivation in going to this mode was to provide a higher frequency of pulses to prevent formation of |