Study on the work mechanism of gas pulse ash remover

Chinese power plants burn a large amount of high-ash coal without washing, so the fouling problems are often serious, especially in the rear portion of the flue gas passage. For instance, the rotary air preheaters are often fouled up so badly that the furnace has to be stopped for mechanical cleaning of the gas passages. The ash deposits cause lowering of heat transfer capacity and rise in flow resistance, resulting in reduction of output and boiler efficiency. Ordinary steam jet blowers and ultra-sonic or infra-sonic devices are not effective against the hard deposits. The gas-explosion soot remover has been used in some Ukrainian power plants. We have developed similar apparatus and applied it to the air preheaters of 200-200 MW power plants with good results. The combustion process in such devices has been studied in our laboratory. The device consists of a combustion chamber for premixed fuel and air and output tube with openings for the gas jet pulse. The pressure rise and turbulent flame propagation in the prototype and a scaled-sown model have been measured with various fuel/air ratios and turbulence-generating setups as experimental parameter. It was found that all these parameters had important effects on the pressure pulse shape. This paper mainly gives results of the laboratory study, but also briefly describes the results of practical application.