Method of introducing dry sulfur oxide absorbent material into a furnace

Claim 1

In a fossil fuel-fired steam generator having a vertically elongated furnace with a gas outlet, steam generating tubes lining the walls of said furnace, fuel injection ports located in a lower region of the furnace remote from the gas outlet thereof, windbox means associated with the fuel injection ports for supplying combustion air to the furnace, and a gas exit duct opening to the gas outlet of said furnace for conveying gases therefrom, a method of firing said furnace comprising: a. combusting a sulfur-bearing fuel in a first quantity of air in a first zone in the lower region of said furnace remote from the gas outlet thereof to generate hot product gases; b. dispersing a sulfur oxide absorbing particulate material in a second quantity of air; c. injecting the sulfur oxide absorbing particulate material dispersed in a second quantity of air into the product gases in a second zone in an upper region of said furnace between the first zone and the gas outlet of said furnace at at least a first and second elevation within the second zone through a plurality of air streams introduced at each elevation; and d. directing the sulfur oxide absorbing particulate material containing air streams introduced at the first elevation tangentially to a first imaginary circle within the second zone, and directing the sulfur oxide absorbing particulate material containing air streams introduced at the second elevation tangentially to a second imaginary circle within the second zone, the first and second imaginary circles having differing radii, the step of dispersing a sulfur oxide absorbing particulate material in a second quantity of air into the product gases in a second zone comprising splitting the second quantity of air into a plurality of air streams, the pluality of air streams subdivided into at least a first and a second portion disposed about the periphery of said furnace at the first and the second elevations respectively; entraining the sulfur oxide absorbing particulate material into a carrier gas; and dispersing a portion of the carrier gas with the entrained sulfur oxide absorbing particulate material into each of the plurality of air streams.