Double Dimension Low NOx Combustion For Mixed Coal In Hengtai Power Plant

By meeting present global environmental regulations, a great effort has beendedicated to research and development. The thermal power plants urgently need a newtechnology to reduce the NOx emissions.At HengTai Power Plant, combustion designed for bituminous coal. But for theseyears, the coal mixed of bituminous coal and lean coal was used. The thermal values ofmixed coal were less than designed coal. It made that the boiler’s efficiency reduced andmore NOx emissions were made exceeding the emission standards. Only denitrifyingthe flue gas does reduce the boiler’s economy while results cannot be guaranteed. Bysolving these problems, a measure fitted for mixed coal was found. It needs low NOxcombustion in boiler first and then denitrifying the flue gas by existing equipment.Based on summary and analysis of low NOx and low nitrogen combustion technologyachievements at home and abroad, researches and transformations of low NOxcombustion were taken under the technology which was named as “double dimension”low NOx combustion. The transformations adopt lateral and vertical air classification,low NOx burner and low NOx function area, and other technical measures ofguaranteeing the boiler economy not reduced. Then, zoning optimization debuggingmethod was used after the transformation carrying out the optimal adjustment test forfurnace exit oxygen content, primary air volume, secondary air volume and burns outair volume. After the twice transformation,11more optimized experiments were carriesout. It was found that the emissions of NOx was decreased from700mg/Nm3to400mg/Nm3or less with doing low NOx combustion before denitrifying the flue gas.The researches and transformations of this paper were created due to the need forhigh efficiency, low NOx, and easy maintenance. The successful application of “doubledimension” low NOx combustion can provide a reference for other similar boilers’transformation.