OCR Text |
Show several modifications suggested by IGT toward facilitating the data collection and to allow optimization. In this particular cyclonic combustor design the low-Btu gases enter the combustor through a tangential nozzle and move down the length of the combustor in a cyclonic motion that is enhanced by an orifice. Combustion air is injected radially through several holes in the combustor wall as well as along the axis of the combustor. The cyclonic motion of the fuel combined with radial and axial air injection and relatively high residence times in contact with hot combustor walls result in good fuel/air mixing and stable flames. The experimental unit has several ports along its length and in the flue for inserting gas sampling and temperature measuring probes and also for measuring the flame length. EXPERIMENTAL SETUP The combustor manufactured by American Schack was tested using simulated low-Btu gases. The basic flow diagram for the tests is shown in Figure 4 and the combustor setup Is shown in Figure 5. The fuel gases for the combustion trials were made first by reacting a mixture of natural gas and steam in a natural gas reformer over a catalyst at 1800°F to generate hydrogen and carbon monoxide. The product gas containing H2, CO, C02, unconverted H20, and small quantities of unconverted natural gas was quenched in water-cooled heat exchangers. The resulting saturated mixture at around 100°F was compressed to 70 psig, and the condensed water was removed in a water separator. Nitrogen, natural gas, carbon dioxide, hydrogen, steam, ammonia, hydrogen sulfide and carbon disulfide were blended in downstream to achieve the required low-Btu gas composition. The higher hydrocarbons were substituted by methane. Combustion air and fuel were preheated in independent natural gas-fired preheaters. MEASUREMENTS AND INSTRUMENTATION A water-cooled probe was used for sampling of the hot gases. A section of heated Teflon tubing was provided at the end of the probe to heat the sample up to 190°F, followed by a Millipore filter to remove any particulates, and a Permapure dryer to reduce the dew point to below 32°F. The dried sample was sent to various analyzers through Teflon tubing. 5.7.7. I N S T I T U T E OF GAS T E C H N O L O GY |