Patent ID: 7832342

Claim:
A method for incinerating waste by combusting fuel in a furnace of a combustion plant having a fuel bed, a flue gas flow above the fuel bed, a combustion grate having a plurality of undergrate air zones and a plurality of independent primary gas supplies arranged beneath the combustion grate, the method comprising the steps of: introducing underfire combustion gas into the fuel bed from below; introducing overfire combustion gas into the flue gas flow; reducing oxygen mass flow of the underfire combustion gas and increasing oxygen mass flow of the overfire combustion gas upon an increase in reaction rate or combustion intensity in the furnace of the combustion plant, different quantities of oxygen being supplied to each of said plural undergrate air zones and different quantities of oxygen being supplied at different times and different locations of the furnace of the combustion plant; and introducing ambient air or internally re-circulated flue gas into the flue gas flow at an introduction level of approximately 6 to 9 meters above the combustion grate; wherein the increase of the oxygen mass flow in the overfire combustion gas substantially corresponds to the reduction of the oxygen mass flow in the underfire combustion gas; wherein the underfire combustion gas and overfire combustion gas are controlled so that the flue gas flow remains constant when the oxygen mass flow of the underfire combustion gas is reduced and oxygen mass flow of the overfire combustion gas is increased; and wherein combustion in the furnace of the combustion plant is controlled such that less oxygen is consumed above the combustion grate when a greater level of oxygen is supplied beneath the incineration grate and such that more oxygen is consumed above the combustion grate when a lower level of oxygen is supplied beneath the incineration grate to achieve optimum incineration of waste on the combustion grate; and wherein the fuel bed is formed on the combustion grate of the furnace.