DEPOSITED-BED BOILER AND METHOD FOR OPERATING SAME WITH REDUCED NITROGEN OXIDE EMISSIONS

摘要

A method for operating a boiler with a deposited fuel bed and a movable grate is disclosed. The method for operating the boiler (10) comprises determining the desired output power of the boiler (10) and the amount of fuel, while adjusting the flow rate of a primary air flow (18) depending on the output power and the measured stoichiometric excess of oxygen, incrementally adjusting the bed height and continuously adjusting the speed of the grate. The method further comprises determining a recycling rate for the flue gas (34) exiting the boiler, and mixing the collected flue gas with the primary air so that the resulting mixture flows at a rate corresponding to the recycling rate. The method is useful for reducing the nitrogen oxide (NOx) content of boiler flue gas.