Radian Corporation

The University of Texas System

Other

Radian Corporation and the Board of Regents

Ronald D Bell

Steven P Nichols

Ronald D Matthews

John R Howell

William C Gardiner

Mark M Koeroghlian

A process and system for low NO.sub.x cogeneration to produce electricity and useful heat. Fuel and oxygen are provided to an internal combustion engine connected to drive an electric generator, to thereby generate electricity. An exhaust stream is recovered from the engine at a temperature of about 500.degree. to 1000.degree. F. which includes from about 6 to 15 percent oxygen. Fuel is added to the exhaust stream to create a fuel-rich mixture, the quantity of fuel being sufficient to react with oxygen and reduce the NO.sub.x in said exhaust stream. The fuel-enriched stream is provided to an afterburner, and the fuel, NO.sub.x and available oxygen are reacted to provide a heated oxygen-depleted stream. The oxygen-depleted stream is cooled in a first heat exchanger. Conversion oxygen is admixed with the cooled stream which is then passed over a catalyst bed under overall reducing conditions. NO is converted to NO.sub.2 at the forward end of the bed, and the NO.sub.2 then reacts on the remainder of the bed with excess combustibles. The stream from the reducing catalyst bed is cooled from a temperature of 750.degree. to 1250.degree. F. to about 450.degree. to 650.degree. F. and air is added to produce a further cooled stream at 400.degree. to 600.degree. F. having a stoichiometric excess of oxygen, and the further cooled stream is passed over an oxidizing catalyst bed to oxidize remaining combustibles. The resultant low NO.sub.x stream can then be provided for venting.

Low NO.sub.x cogeneration process and system

A method and corresponding system are provided for reducing quantities of oxides of nitrogen, including N.sub.2 O, that are generated in a coal-fired fluidized bed boiler, the exhaust stream from the fluidized bed boiler being at a temperature of about 600.degree.-650.degree. F. and including from about 3 to 6% oxygen, from about 50 to 500 ppmv of NO.sub.x and from about 50 to 300 ppmv of N.sub.2 O. Pursuant to the invention, the exhaust stream is flowed through a thermal reaction zone at which fuel and air are burned, to provide a modified heated stream which includes small quantities of combustibles and of oxygen. The modified heated stream is passed over a first catalyst bed under overall reducing conditions, the quantity of oxygen in the stream being in stoichiometric excess of the amount of NO.sub.2 O and NO.sub.x, but less than the amount of said combustibles; whereby the N.sub.2 O and NO.sub.x are first oxidized to NO.sub.2, and then the NO.sub.2 is reduced by the excess combustibles. The stream from the first catalyst bed is cooled by passing it through a heat exchanger. Air is added to the resulting stream from the heat exchanger to produce a further cooled stream having a stoichiometric excess of oxygen. The further cooled stream is then passed over an oxidizing catalyst bed to oxidize remaining excess combustibles, to thereby provide an effluent stream having environmentally safe characteristics.

Low NO.sub.x combustion process and system

Apparatus for controlled low NO.sub.x combustion. First and second combustion zones are provided, each filled with a porous high temperature resistant matrix, the void spaces of which provide sites at which substantially all of the combustion occurs. The second zone is downstream of the first zone. Means are provided for mixing fuel and a gaseous source of oxygen and providing the resultant combustible mixture to the input end of the first combustion zone to establish fuel-lean conditions therein; and means for feeding the combustion products from the first zone to the second zone and augmenting same with further oxygen and sufficient additional fuel to create fuel-rich burning conditions therein to complete the oxidation of the products from the first zone. Cooling means are preferably mounted in proximity to the input end of the first combustion zone, for maintaining the temperature of the said combustible mixture at the input end below ignition temperature, thereby limiting the flame produced by combustion in the porous matrix to the downstream side of the cooling means. The corresponding method is also disclosed and claimed.

Apparatus and method for combustion within porous matrix elements

Burner apparatus for use in controlled low NO.sub.x combustion. Mixing and flow-directing means receive and mix fuel and air provided thereto and form a flow of the resulting combustible mixture. A combustion zone defined by a porous high temperature-resistant matrix includes an input end for receiving the combustible flow. Cooling means are mounted in proximity to the input end of the combustion zone, for maintaining the temperature of the flowing combustible mixture proximate the input end below ignition temperature, thereby limiting the flame produced by combustion in the porous matrix to the downstream side of the cooling means. The method for controlled low NO.sub.x combustion is also disclosed and claimed.

Low NO.sub.x combustion is effected by a method wherein a fuel, e.g., natural gas, and a source of oxygen, e.g., air, are mixed and the mixture is combusted in at least two successive combustion zones filled with a porous matrix, the void spaces of which provide sites at which substantially all of the said combustion occurs; viz. a first zone wherein the mixture is fuel-rich, and a second zone wherein the mixture is fuel-lean. Preferably, the method utilizes an additional combustion zone which precedes or is upstream of the first zone and is filled with a said porous matrix, wherein the mixture is fuel-lean. Apparatus for low NO.sub.x combustion is also provided which includes an arrangement for mixing fuel and oxygen, and at least first and second combustion zones filled with a said porous matrix, and means for providing a fuel-oxygen mixture to said first zone which is fuel rich, and for adjusting the resulting combustion products flowed to the second zone with additional fuel and oxygen as to provide a fuel-lean mixture therein. Preferably the apparatus also includes a zone or stage filled with a said porous matrix which precedes or is upstream of the first zone, to which the fuel and oxygen are initially provided as to establish fuel-lean conditions therein.

Combustion method and apparatus for staged combustion within porous

A process and system for low NO.sub.x cogeneration to produce electricity and useful heat. Fuel and oxygen are provided to an internal combustion engine connected to drive an electric generator, to thereby generate electricity. An exhaust stream is recovered from the engine at a temperature of about 500.degree. to 1000.degree. F. which includes from about 6 to 15 percent oxygen. Fuel is added to the exhaust stream to create a fuel-rich mixture, the quantity of fuel being sufficient to react with the oxygen and reduce the NO.sub.x in said exhaust stream. The fuel-enriched stream is provided to an afterburner, and the fuel, NO.sub.x and available oxygen are reacted to provide a heated oxygen-depleted stream. The oxygen-depleted stream is cooled in a heat exchanger. Conversion oxygen is admixed with the cooled stream which is then passed over a catalyst bed under overall reducing conditions. NO is converted to NO.sub.2 at the forward end of the bed, and the NO.sub.2 then reacts on the remainder of the bed with excess combustibles. Air is added to the resulting stream from the catalyst bed to produce a cooled stream having a stoichiometric excess of oxygen, and the cooled stream is passed over an oxidizing catalyst bed to oxidize remaining combustibles. The resultant low NO.sub.x stream can then be provided for venting.

A process for low NOX incineration which involves incinerating hazardous waste to produce a gaseous stream, adding combustible material to produce a combustible gas stream having combustible material in excess of the oxygen in the combustible gas stream, incinerating the combustible gas stream in a reducing atmosphere to produce a heated oxygen-depleted gaseous stream, converting at least a portion of the heat in the oxygen depleted stream into steam, adding air to the oxygen depleted stream to produce a stoichiometric excess of oxygen in the resultant stream relative to combustible material present in the resultant stream, passing the resultant stream over an oxidizing catalyst to produce an oxidized gaseous stream, removing heat from the oxidized stream, and venting the resultant cooled stream. A system for carrying out the foregoing process is also provided.

Low NOX incineration process

A process for low NOX combustion which involves combusting an oxygen-containing combustible gas stream having fuel material in excess of the oxygen in the combustible gas stream, whereby the combustible gas stream is combusted in a reducing atmosphere to produce a heated oxygen-depleted gaseous stream, converting at least a portion of the heat in the oxygen-depleted depleted stream into steam, adding air to the oxygen-depleted stream to produce a stoichiometric excess of oxygen in the resultant stream relative to fuel material present in the resultant stream, passing the resultant stream over the oxidizing catalyst to produce an oxidized gaseous stream, optionally removing heat from the oxidized stream, and venting the resultant cooled stream. A system for carrying out the foregoing process is also provided.

Low NOX combustion process

A process for low NOX cogeneration to produce electricity and heat which involves combusting fuel to produce a gaseous stream of combustion products, passing the gaseous stream through a turbine to generate electricity, and to produce a gaseous exhaust stream, adding additional fuel to the exhaust stream, to provide a fuel-rich gas stream having fuel in excess of the oxygen in the combustible gas stream, treating the fuel-rich gas stream in a reducing atmosphere to produce a heated oxygen-depleted gaseous stream, converting at least a portion of the heat in the oxygen depleted stream into steam, adding air to the oxygen-depleted stream to produce a stoichiometric excess of oxygen in the resultant stream relative to fuel present in the resultant stream, passing the resultant stream over an oxidizing catalyst to produce an oxidized gaseous stream, removing heat from the oxidized stream, and venting the resultant cooled stream, the process further providing for cycling to the combusting step at least some of the oxidized gaseous stream. An apparatus system for carrying out this process is also provided.

Low NOX cogeneration process

A process for low NOX cogeneration to produce electricity and heat which involves combusting fuel to produce a gaseous stream of combustion products, passing the gaseous stream through a turbine to generate electricity, and to produce a gaseous exhaust stream, adding additional fuel to the exhaust stream, to provide a gas stream having fuel in excess of the oxygen in the fuel-rich gas stream, catalytically treating the gas stream in a reducing atmosphere to produce a treated gaseous stream, converting at least a portion of the heat in the treated stream into steam, adding air to the treated stream to produce a stoichiometric excess of oxygen in the resultant stream relative to fuel present in the resultant stream, passing the resultant stream over an oxidizing catalyst to produce an oxidized gaseous stream, removing heat from the oxidized stream, and venting the resultant cooled stream. An apparatus system for carrying out this process is also provided.

Growing community of inventors

Austin, TX, United States of America

Ronald D Bell