Method and apparatus for operating a fuel flexible furnace to reduce pollutants in emissions

A fuel flexible furnace, comprising:

• a main combustion zone;
• a reburn zone downstream from the main combustion zone;
• and
• a delivery system operably coupled to supplies of biomass and coal and configured to deliver the biomass and the coal as ingredients of first and reburn fuels to the main combustion zone and the reburn zone, with each fuel including flexible quantities of the biomass and/or the coal, wherein
• the flexible quantities variable with the furnace in an operating condition, wherein the delivery system comprises:
• burners, to be supplied with the first and the reburn fuels, which are configured to fire into the main combustion zone;
• at least one injector configured to inject the first and the reburn fuels into the reburn zone;
• a coal feed system to provide pulverized coal as the supply of the coal for the first fuel and the reburn fuel;
• and
• a biomass supply system to provide a mixture of the supply of the biomass and a carrier gas for the first fuel and the reburn fuel, wherein
• the supply of the biomass comprises biomass particles having sizes in a range from approximately 0.2 mm to approximately 2 mm in size, and
• the biomass supply system comprises storage devices, a particle size reducing apparatus, and a mixer, in which the biomass particles are mixed with the carrier gas,
• wherein the carrier gas comprises ambient air, preheated combustion air diverted from the main combustion zone, recirculated flue gas (RFG), steam, inert gas, and/or a combination thereof, and
• further comprising a thermocouple to measure a carrier gas temperature, the measurement being employed to determine a mixing ratio of ingredients of the carrier gas.