Apparatus and method of lowering NO.sub.x emissions using diffusion processes
AssigneeConsolidated Natural Gas Service Company, Inc.
InventorsBernard P. Breen, Steven E. Winberg, James E. Gabrielson, James C. McMichael
Life of this patent
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Abstract
An apparatus and method for reducing nitrogen oxide emissions from furnace flue gas is provided in which natural gas or other fluid fuel which has little or no fixed nitrogen is introduced into the upper portion of the furnace. The fuel diffuses by laminar or turbulent diffusion into oxygen-rich flue gas where it reacts with oxygen and nitric oxide to form CO.sub.2, H.sub.2 O and N.sub.2, thus reducing the nitrogen oxide emissions from the furnace. In this manner, the amount of nitrogen oxide in the flue gas is reduced. The apparatus and method can be easily applied to new furnaces or retrofitted on existing furnaces.
Claims40
An improved apparatus for reducing nitrogen oxide in flue gas in a combustion furnace burning at least one of coal and coke having a primary combustion zone wherein the improvement comprises:
- means forming at least one fuel introducing device attached to the furnace above the primary combustion zone which introduces into said flue gas a steady stream of fluid fuel which diffuses into said flue gas, said fluid fuel being selected from the group of fluids consisting of natural gas, hydrogen, C.sub.x H.sub.y compounds and C.sub.x H.sub.y O.sub.z compounds and mixtures of said fluids.
An improved apparatus for reducing nitrogen oxide in the flue gas in a furnace having a convective zone wherein the improvement comprises:
- means forming at least one-fuel introducing device in or after said convective zone which introduces into said flue gas a steady stream of fluid fuel which diffuses into said flue gas, said fluid fuel being selected from the group of fluids consisting of natural gas, hydrogen, C.sub.x H.sub.y compounds and C.sub.x H.sub.y O.sub.z compounds and mixtures of said fluids.
An in-furnace method for reducing oxygen in flue gas comprising the step of:
- injecting a stream of fluid fuel into said flue gas so it diffuses therein, said fluid fuel being selected from the group of fluids consisting of natural gas, hydrogen, C.sub.x H.sub.y compounds,
- C.sub.x H.sub.y O.sub.z compounds and mixtures primarily of those compounds, in sufficient quantity to promote a reaction between said nitrogen oxide in the flue gas and said fluid fuel, so as to substantially reduce said nitrogen oxide content of said flue gas.
An improved apparatus for reducing nitrogen oxide in flue gas in a combustion furnace having a primary combustion zone wherein the improvement comprises at least one porous device for introducing fuel attached to the furnace above the primary combustion zone which introduces into said flue gas a stream of fluid fuel which diffuses into said flue gas, said fluid fuel being selected from the group of fluids consisting of natural gas, hydrogen, C.sub.x H.sub.y compounds and C.sub.x H.sub.y O.sub.z compounds and mixtures of said fluids.
Dependencies are inferred from the claim text.