OCR Text |
Show Superheating of the secondary stream to the desired temperature (ca 590 K) was accomplished by an electric heater. The flow rate of each gas tracer was controlled with a gas cylinder regulator to provide constant pressure upstream of a small choked flow nozzle. A hydrogen/air ignitor was used to light a methane/oxygen flame, which was then used to preheat the reactor walls and to ignite a coal/methane/oxygen mixture. Once ignition of the coal was achieved, the methane was turned off. The steam flow was then begun, the flows were adjusted to the desired levels, and the coal flame was allowed to burn for 5-10 minutes. After this time, approximately steady wall temperatures were achieved, and gas and particle samples were obtained from within the gasifier with the traversing sample probe. Sample collection times varied between 1-2 minutes at each of several radial locations. The exhaust stream from the gasifier was quenched with a water spray and exhausted through a scrubber. The coal was fed from a single solid-core auger at a rate of 24.5 kg/hr. An intromitter, which enclosed the feeder auger, and a six-vane stirrer were installed to keep the coal bed well stirred ana to provide a smooth coal feed rate. Probe and Sample Collection A single traversing water-quenched probe was installed in the probe test section. The probe was about 9.5 mm OD with 4.0 mm ID. Coolant water was injected into the sample port near the probe tip to quench the gas and particle reations by direct contact and to prevent particles from adhering to the probe walls. During the sampling period, the gas-liquid-solid samples from the probes were separated into gaseous and solid-liquid fractions. The dried gases were collected in commercial plastic gas collection bags for later chromatographic analysis. The char was filtered from the liquid and dried. The liquid samples were collected and analyzed for S=, SO3, CN", and NH3 products resulting from the hydrolysis reactions of water with H^S, SO2, HCN, and MHo gases. Sample Analysis Several techniques have been employed to analyze the effluents from the reactor (4,8-13) including permanent gases (CO, C02, H2, CH4, Ar, N2, 6-5 |