초록 ▼

A method and apparatus for reducing NO.sub.x emissions from the combustion of carbonaceous fuels using three stages of oxidation. In the first stage, a partial oxidation combustor is used to partially combust the fuel in the presence of heated combustion air. The fuel gas produced in the partial oxi

A method and apparatus for reducing NO.sub.x emissions from the combustion of carbonaceous fuels using three stages of oxidation. In the first stage, a partial oxidation combustor is used to partially combust the fuel in the presence of heated combustion air. The fuel gas produced in the partial oxidation process is passed to a second stage partial oxidation combustor while molten slag is removed and disposed of. A second preheated combustion air is introduced into the second stage combustor to produce a reducing flue gas. A third combustion air is mixed with the flue gas in a third stage combustor to substantially complete the combustion process. Preheated steam may be added at any or all of the combustion stages. The stochiometric ratios at each stage of combustion are controlled to minimize overall NO.sub.x emissions to acceptable levels. An excess air cyclone-fired furnace modified to operate in a three-stage combustor mode by adding a preheated air system, with air introduction into the furnace at the cyclone barrel re-entrant throat location followed by overfire air introduction in the upper part of the furnace can be utilized to provide the three stages of combustion.

대표청구항 ▼

[ What is claimed is:] [1.] A method for reducing nitrogen oxide (NO.sub.x) emissions formed during the combustion of a carbonaceous fuel, said method comprising the steps of:a) introducing a carbonaceous fuel containing fuel bound nitrogen into first stage partial oxidation unit, wherein primary ca

[ What is claimed is:] [1.] A method for reducing nitrogen oxide (NO.sub.x) emissions formed during the combustion of a carbonaceous fuel, said method comprising the steps of:a) introducing a carbonaceous fuel containing fuel bound nitrogen into first stage partial oxidation unit, wherein primary carrier air and preheated secondary air are added and mixed with the carbonaceous fuel to produce a fuel gas;b) introducing the fuel gas into a second stage of partial oxidation and introducing preheated tertiary air into the fuel gas;c) introducing the fuel gas and preheated tertiary air into a boiler furnace, flowing through a radiant section of the boiler furnace to produce a flue gas; andd) introducing said flue gas into a third stage of oxidation where preheated overfire air is introduced into the furnace boiler to substantially complete the combustion process.