Furnace apparatus and method

Claim 3

The method defined in claim 1 wherein the amount of air supplied in said first mixture is from about 50 to 90 percent of the stoichiometric amount of air.

Claim 4

The method defined in claim 1 wherein the carbonaceous fuel is solid fuel and wherein the amount of air supplied in said first mixture is from about 55 to 80 percent of the stoichiometric amount of air.

Claim 5

The method defined in claim 1 wherein the carbonaceous fuel is a liquid or gaseous hydrocarbon and wherein the amount of air supplied in said first mixture is from about 80 to 90 percent of the stoichiometric amount of air.

Claim 6

The method defined in claim 1 wherein the operating temperature of the catalyst is in the range from about 1700° to about 3200° F.

Claim 7

The method defined in claim 1 wherein the operating temperature of the catalyst is in the range from about 2000° to about 3000° F.

Claim 8

The method defined in claim 1 wherein at least a portion of the energy produced by said method is heat withdrawn from the gaseous effluent of the combustion taking place in the presence of the catalyst.

Claim 9

The method defined in claim 1 wherein said additional amount of air includes at least enough free oxygen to complete combustion to carbon dioxide and water of all the combustible components in the gaseous first effluent.

Claim 10

The method defined in claim 1 wherein at least some of the energy in the final combustion effluent of said method is recovered to preheat at least some of the air supplied in at least one of said first and second mixtures.

Claim 11

The method defined in claim 1 wherein the gaseous first effluent contains from about 10 to 30 volume percent carbon monoxide.

Claim 22

The method defined in claim 14, wherein the said combustion taking place in the presence of said catalyst is carried out under essentially adiabatic conditions.

Claim 25

The method defined in claim 17 wherein the adiabatic flame temperature of said second mixture is in the range from about 2000° to about 3000° F.

Claim 26

The method defined in claim 17 wherein a portion of the final combustion effluent of said method is recycled and admixed with said first combustion mixture.

Claim 27

The method defined in claim 17 wherein a portion of the final combustion effluent of said method is recycled to provide said inert gases for said second mixture.

Claim 28

The method defined in claim 17 wherein said combusting of at least a portion of said second mixture is carried out under essentially adiabatic conditions.

Claim 33

A furnace for burning solid carbonaceous fuel to produce energy in the form of heat comprising: a combustion housing having a solid fuel inlet port, a solid residue outlet port, and a gaseous effluent outlet port above the fuel inlet port and solid residue outlet port; conveyor means for conveying solid carbonaceous fuel disposed thereon through the combustion housing from said fuel inlet port to said solid residue outlet port; air inlet means for introducing into the combustion housing below said conveyor means an amount of air substantially less than that needed for complete combustion to carbon dioxide and water of all the combustible components in said fuel to effect thermal combustion of said solid carbonaceous fuel and produce a gaseous first effluent containing a substantial proportion of carbon monoxide; first heat transfer means associated with said combustion housing for withdrawing heat therefrom; means for forming a mixture of said gaseous first effluent and additional air, said mixture having an adiabatic flame temperature above the instantaneous auto-ignition temperature of said mixture; Additional combustion means including a solid oxidation catalyst for combusting at least a portion of said mixture in the presence of said catalyst operating at a temperature substantially above the instantaneous auto-ignition temperature of said second mixture but below a temperature that would result in any substantial formation of oxides of nitrogen to produce a gaseous second effluent; and second heat transfer means, associated with said second combustion means, for withdrawing heat from said gaseous second effluent.

Claim 34

A furnace for burning solid carbonaceous fuel to produce energy in the form of heat comprising: a combustion housing having a solid fuel inlet port, a solid residue outlet port, and a gaseous effluent outlet port above the fuel inlet port and solid residue outlet port; conveyor means for conveying solid carbonaceous fuel disposed thereon through the combustion housing from said fuel inlet port to said solid residue outlet port; air inlet means for introducing into the combustion housing below said conveyor means an amount of air substantially less than that needed for complete combustion to carbon dioxide and water of all the combustible components in said fuel to effect thermal combustion of said solid carbonaceous fuel and produce a gaseous first effluent containing a substantial proportion of carbon monoxide; first heat transfer means associated with said combustion housing for withdrawing heat therefrom; means for forming a mixture of said gaseous first effluent and additional air, said mixture having an adiabatic flame temperature above the instantaneous auto-ignition temperature of said mixture; Additional combustion means including a solid oxidation catalyst for combusting at least a portion of said mixture in the presence of said catalyst operating at a temperature substantially above the instantaneous auto-ignition temperature of said second mixture but below a temperature that would result in any substantial formation of oxides of nitrogen to produce a gaseous second effluent; and second heat transfer means, associated with said second combustion means, for withdrawing heat from said gaseous second effluent.

Claim 35

The furnace defined in claim 24 wherein said additional combustion means, said oxidation catalyst included therein, and said second heat transfer means associated therewith are arranged for combusting at least said portion of said second mixture under essentially adiabatic conditions.

Claim 36

The furnace defined in claim 24 wherein said air inlet means further comprises: a plurality of air inlet ports spaced lengthwise of the conveyor means in the combustion housing; and air distribution means for distributing a predetermined portion of said amount of air to each of said air inlet ports.

Claim 37

The furnace defined in claim 24 further comprising heat exchange means for recovering some of the thermal energy in the final combustion effluent of said furnace to preheat the air supplied to said air inlet means.

Claim 38

The furnace defined in claim 24 further comprising heat exchange means for recovering some of the thermal energy in the final combustion effluent of said furnace to preheat the air supplied to the means for forming said mixture with said gaseous first effluent.

Claim 39

A furnace for burning carbonaceous fuel to produce energy in the form of heat comprising: first combustion means for thermally combusting a first mixture, formed of the carbonaceous fuel and an amount of air substantially less than that needed for complete combustion to carbon dioxide and water of all the combustible components in said fuel, to produce a gaseous first effluent containing a substantial proportion of carbon monoxide; first heat transfer means, associated with said first combustion means, for withdrawing heat from said first combustion means; means for forming a second mixture of said gaseous first effluent and additional air having an adiabatic flame temperature above the instantaneous auto-ignition temperature of said second mixture; second combustion means including a solid oxidation catalyst for combusting at least a portion of said second mixture in the presence of said catalyst operating at a temperature substantially above the instantaneous auto-ignition temperature of said second mixture but below a temperature that would result in any substantial formation of oxides of nitrogen to produce a gaseous second effluent. second heat transfer means, associated with said second combustion means, for withdrawing heat from said gaseous second effluent; and means for recycling a portion of the final combustion effluent of said furnace to said first combustion means.

Claim 40

A furnace for burning carbonaceous fuel to produce energy in the form of heat comprising: first combustion means for thermally combusting a first mixture, formed of the carbonaceous fuel and an amount of air substantially less than that needed for complete combustion to carbon dioxide and water of all the combustible components in said fuel, to produce a gaseous first effluent containing a substantial proportion of carbon monoxide; first heat transfer means, associated with said first combustion means, for withdrawing heat from said first combustion means; means for forming a second mixture of said gaseous first effluent and additional air having an adiabatic flame temperature above the instantaneous auto-ignition temperature of said second mixture; second combustion means including a solid oxidation catalyst for combusting at least a portion of said second mixture in the presence of said catalyst operating at a temperature substantially above the instantaneous auto-ignition temperature of said second mixture but below a temperature that would result in any substantial formation of oxides of nitrogen to produce a gaseous second effluent. second heat transfer means, associated with said second combustion means, for withdrawing heat from said gaseous second effluent; and means for recycling a portion of the final combustion effluent of said furnace to said first combustion means.

Claim 41

The furnace defined in claim 29 further comprising means for mixing the recycled final combustion effluent in predetermined proportion with the air to be supplied to said first mixture for combustion in the first combustion means.

Claim 42

A furnace for burning carbonaceous fuel to produce energy in the form of heat comprising: first combustion means for thermally combusting a first mixture, formed of the carbonaceous fuel and an amount of air substantially less than that needed for complete combustion to carbon dioxide and water of all the combustible components in said fuel, to produce a gaseous first effluent containing a substantial proportion of carbon monoxide; first heat transfer means, associated with said first combustion means, for withdrawing heat from said first combustion means; means for forming a second mixture of said gaseous first effluent and additional air, said second mixture having an adiabatic flame temperature above the instantaneous auto-ignition temperature of said second mixture; second combustion means including a solid oxidation catalyst for combusting at least a portion of said second mixture in the presence of said catalyst operating at a temperature substantially above the instantaneous auto-ignition temperature of said second mixture but below a temperature that would result in any substantial formation of oxides of nitrogen to produce a gaseous second effluent; second heat transfer means, associated with said second combustion means, for withdrawing heat from said gaseous second effluent; and means for recycling a portion of the final combustion effluent of the furnace by mixing said final effluent in predetermined proportion with said additional air supplied to said means for forming the second mixture.

Claim 43

A furnace for burning carbonaceous fuel to produce energy in the form of heat comprising: first combustion means for thermally combusting a first mixture, formed of the carbonaceous fuel and an amount of air substantially less than that needed for complete combustion to carbon dioxide and water of all the combustible components in said fuel, to produce a gaseous first effluent containing a substantial proportion of carbon monoxide; first heat transfer means, associated with said first combustion means, for withdrawing heat from said first combustion means; means for forming a second mixture of said gaseous first effluent and additional air, said second mixture having an adiabatic flame temperature above the instantaneous auto-ignition temperature of said second mixture; second combustion means including a solid oxidation catalyst for combusting at least a portion of said second mixture in the presence of said catalyst operating at a temperature substantially above the instantaneous auto-ignition temperature of said second mixture but below a temperature that would result in any substantial formation of oxides of nitrogen to produce a gaseous second effluent; second heat transfer means, associated with said second combustion means, for withdrawing heat from said gaseous second effluent; and means for recycling a portion of the final combustion effluent of the furnace by mixing said final effluent in predetermined proportion with said additional air supplied to said means for forming the second mixture.

Claim 44

A furnace for burning carbonaceous fuel to produce energy in the form of heat comprising: first combustion means for thermally combusting a first mixture, formed of the carbonaceous fuel and an amount of air substantially less than that needed for complete combustion to carbon dioxide and water of all the combustible components in said fuel, to produce a gaseous first effluent containing a substantial proportion of carbon monoxide; first heat transfer means, associated with said first combustion means, for withdrawing heat from said first combustion means; means for forming a second mixture of said gaseous first effluent and additional air sufficient to oxidize only a portion of the combustible components in said first effluent to carbon dioxide and water, said second mixture having an adiabatic flame temperature above the instantaneous auto-ignition temperature of said second mixture; second combustion means including a solid oxidation catalyst for combusting at least a portion of said second mixture in the presence of said catalyst operating at a temperature substantially above the instantaneous auto-ignition temperature of said second mixture but below a temperature that would result in any substantial formation of oxides of nitrogen to produce a gaseous second effluent; second heat transfer means associated with said second combustion means, for withdrawing heat from said gaseous second effluent; means for forming a third mixture of said gaseous second effluent and a further amount of air to produce a third mixture having an adiabatic flame temperature above the instantaneous auto-ignition temperature of said third mixture; third combustion means including a further solid oxidation catalyst for combusting at least a portion of said third mixture in the presence of said further catalyst at a temperature substantially above said instantaneous auto-ignition temperature of said third mixture but below a temperature that would result in any substantial formation of oxides of nitrogen to produce a gaseous third effluent; and third heat transfer means, associated with said third combustion means, for withdrawing heat from said gaseous third effluent.

Claim 45

A furnace for burning carbonaceous fuel to produce energy in the form of heat comprising: first combustion means for thermally combusting a first mixture, formed of the carbonaceous fuel and an amount of air substantially less than that needed for complete combustion to carbon dioxide and water of all the combustible components in said fuel, to produce a gaseous first effluent containing a substantial proportion of carbon monoxide; first heat transfer means, associated with said first combustion means, for withdrawing heat from said first combustion means; means for forming a second mixture of said gaseous first effluent and additional air sufficient to oxidize only a portion of the combustible components in said first effluent to carbon dioxide and water, said second mixture having an adiabatic flame temperature above the instantaneous auto-ignition temperature of said second mixture; second combustion means including a solid oxidation catalyst for combusting at least a portion of said second mixture in the presence of said catalyst operating at a temperature substantially above the instantaneous auto-ignition temperature of said second mixture but below a temperature that would result in any substantial formation of oxides of nitrogen to produce a gaseous second effluent; second heat transfer means associated with said second combustion means, for withdrawing heat from said gaseous second effluent; means for forming a third mixture of said gaseous second effluent and a further amount of air to produce a third mixture having an adiabatic flame temperature above the instantaneous auto-ignition temperature of said third mixture; third combustion means including a further solid oxidation catalyst for combusting at least a portion of said third mixture in the presence of said further catalyst at a temperature substantially above said instantaneous auto-ignition temperature of said third mixture but below a temperature that would result in any substantial formation of oxides of nitrogen to produce a gaseous third effluent; and third heat transfer means, associated with said third combustion means, for withdrawing heat from said gaseous third effluent.

Claim 46

The furnace defined in claim 32 wherein said second combustion means, said third combustion means, and said oxidation catalysts associated individually therewith are arranged for combustion in said respective combustion means under essentially adiabatic conditions.

Claim 47

A furnace for burning carbonaceous fuel to produce energy in the form of heat comprising: first combustion means for thermally combusting a first mixture, formed of the carbonaceous fuel and an amount of air substantially less than that needed for complete combustion to carbon dioxide and water of all the combustible components in said fuel, to produce a gaseous first effluent containing a substantial proportion of carbon monoxide; first heat transfer means, associated with said first combustion means, for withdrawing heat from said first combustion means; means for forming a second mixture of said gaseous first effluent and an amount of additional air at least sufficient for combustion to carbon dioxide and water of all the combustible components in all of said first effluent, said second mixture having an adiabatic flame temperature above the instantaneous auto-ignition temperature of said second mixture; second combustion means including a solid oxidation catalyst for combusting at least a portion of said second mixture in the presence of said catalyst operating at a temperature substantially above the instantaneous auto-ignition temperature of said second mixture but below a temperature that would result in any substantial formation of oxides of nitrogen to produce a gaseous second effluent; second heat transfer means, associated with said second combustion means, for withdrawing heat from said gaseous second effluent; means for forming a third mixture of said gaseous second effluent and at least a portion of the gaseous first effluent not supplied in said second mixture, said third mixture having an adiabatic flame temperature above the instantaneous auto-ignition temperature of said third mixture; third combustion means including a further solid oxidation catalyst for combusting at least a portion of said third mixture in the presence of said further catalyst at a temperature substantially above said instantaneous auto-ignition temperature of said third mixture but below a temperature that would result in any substantial formation of oxides of nitrogen to produce a gaseous third effluent; and third heat transfer means, associated with said third combustion means, for withdrawing heat from said gaseous third effluent.

Claim 48

A furnace for burning carbonaceous fuel to produce energy in the form of heat comprising: first combustion means for thermally combusting a first mixture, formed of the carbonaceous fuel and an amount of air substantially less than that needed for complete combustion to carbon dioxide and water of all the combustible components in said fuel, to produce a gaseous first effluent containing a substantial proportion of carbon monoxide; first heat transfer means, associated with said first combustion means, for withdrawing heat from said first combustion means; means for forming a second mixture of said gaseous first effluent and an amount of additional air at least sufficient for combustion to carbon dioxide and water of all the combustible components in all of said first effluent, said second mixture having an adiabatic flame temperature above the instantaneous auto-ignition temperature of said second mixture; second combustion means including a solid oxidation catalyst for combusting at least a portion of said second mixture in the presence of said catalyst operating at a temperature substantially above the instantaneous auto-ignition temperature of said second mixture but below a temperature that would result in any substantial formation of oxides of nitrogen to produce a gaseous second effluent; second heat transfer means, associated with said second combustion means, for withdrawing heat from said gaseous second effluent; means for forming a third mixture of said gaseous second effluent and at least a portion of the gaseous first effluent not supplied in said second mixture, said third mixture having an adiabatic flame temperature above the instantaneous auto-ignition temperature of said third mixture; third combustion means including a further solid oxidation catalyst for combusting at least a portion of said third mixture in the presence of said further catalyst at a temperature substantially above said instantaneous auto-ignition temperature of said third mixture but below a temperature that would result in any substantial formation of oxides of nitrogen to produce a gaseous third effluent; and third heat transfer means, associated with said third combustion means, for withdrawing heat from said gaseous third effluent.