Reduction of nitrogen oxide emission from steam boilers - by burning coal dust with melt firing to evaporate nitrogen and sulphur before combustion

摘要

The process claimed in the parent patent for preheating coal dust fuel for steam boilers at 800 degrees C for 4 sec. with (part of) the gas produced being burnt in the steam boiler after purification and opt. reheating, is extended to cover steam boilers with melt-firing. The treated coal is used directly or stored. Around 50-75% of the nitrogen and the sulphur present in the coal pass into the gas phase during the preheating, with a corresp. reduction in emission of polluting gases from the boilers. This allows increased use of coal in place of oil e.g. in power stations.