Process for reducing the emission of dust, SO2 and NOx of a steam generator having a flue gas denitration plant

摘要

In the operation of a steam generator having a flue gas desulphurization plant and denitration plant, in order to heat the desulphurized flue gases to a temperature optimal for the denitration without the use of an external heat supply being required, and at the same time to perform a primary NOx reduction by flue gas circulation and in the case of coal-dust-fired furnaces to inertize the mills and dust pipes, a part-stream of the flue gases is taken off from the combustion chamber or between the downstream heating surfaces of the steam generator, used for reheating the desulphurized flue gases prior to entry into the denitration plant and then, with or without the addition of cold air for temperature control, is introduced in whole or in part to the mills and/or in whole or in part above and/or beneath the burners and/or through the burners into the combustion chamber, the part-reheating of the desulphurized flue gases being carried out either by the flue gases taken off from the combustion chamber or between the downstream heating surfaces in a heat exchanger arranged between desulphurization plant and denitration plant or being carried out in a regenerative trisector clean gas preheater.