OCR Text |
Show experimental study in the dual- and - multiple-layer porous burner was performed at the Institute of Gas Technology (IGT) (21). Flames can be stabilized in a porous system in a relatively large range of firing rates. Very high combustion intensity, up to 500 X 103 Btu(h2_ft2 (1.6 MW/m2), was achieved. Based on the preliminary testing, a more extensive experimental study was further conducted in a modified porous burner system to define the range of stable combustion and to evaluate thermal performance as well as combustion emissions. In this paper, the major experimental results with emphasis on flame stabilizat-ion within the porous medium, radiant heat output from the burner, and combustion emissions will be presented. EXPERIMENTAL APPARATUS The purpose of the experimental study was to evaluate a bench-scale porous-combustion radiant burner for concept proof. Specifically, work efforts were aimed at exploration of combustion stabilization within the porous media, radiant heat transmission, and combustion emissions. SETUP A schematic diagram of the experimental setup, containing natural gas and combustion air supply, the test burner and the measurement system, is shown in Figure 2. The burner unit consists of five parts connected together • Natural gas/air mixture inlet plenum • Distribution screen and grate • Porous matrix bed • Exhaust plenum • Support frame with legs. Natural gas supplied from the central gas line in the laboratory and combustion air provided by an air compressor is mixed in a mixer, which is located quite far from the burner inlet plenum for perfect premixing. The mixture of gas and air is brought into the unit through a 2-1/2 inch inlet plenum. The mixture is then uniformly distributed through a honeycomb grate. The burner unit consists of a distribution grate placed at the bottom to support the matrix bed, porous bed, and a radiating surface put on top of the unit. An exhaust plenum is placed above the burner unit to provide a uniform flow stream for measurement of gas composition and temperature in the flue gas. Only ceramic materials are temperatures in the porous burner. capable of working at such high To examine the effect of the porous |