A LOW-NOx FUEL INJECTION FOR A HAIR BED

专利摘要:
One method delivers fuel gas to a furnace combustion chamber from a premix burner comprising a reaction zone having an outlet to the furnace combustion chamber. This includes the steps of injecting a premix of primary fuel gas and combustion air into the reaction zone, and burning the premix to provide combustion products comprising oxygen-poor combustion air into the reaction zone. Further steps include injecting staged fuel gas into the reaction zone separate from the premix, discharging the stepped fuel gas and deoxygenated combustion air from the reaction zone through the outlet to the furnace combustion chamber, and burning the stepped fuel combustion fuel gas and oxygen fuel combustion fuel. This makes it possible to achieve low-NO combustion in the furnace combustion chamber as a result of interacting the stepped fuel gas with the oxygen-poor combustion air in the reaction zone.
公开号:SE1450256A1
申请号:SE1450256
申请日:2012-08-10
公开日:2014-03-06
发明作者:Bruce E Cain；Thomas F Robertson；Mark C Hannum；Todd A Miller；Joseph P Brown
申请人:Fives North American Comb Inc；
IPC主号:

专利说明:

and then out of the oven 20. The process stations include drying, heating, and cooling stations. In this example, the drying stations include an upflow drying station 30 and a downflow drying station 32. The heating stations include preheating stations 34 and firing stations 36. First and second cooling stations 38 and 40 are located between firing stations 36 and the furnace outlet 42. Burners 44 are provided and preheating.
A blowing station system 50 drives air to circulate through the furnace 20 along flow paths indicated by the arrows shown in Fig. 1. As pelleted material 26 proceeds from the firing stations 36 toward the outlet 42, it is cooled by the incoming air at the first and second cooling stations 38. and 40. This causes the incoming air to heat up before it reaches the burners 44. The preheated air at the second cooling station 40 is directed through a duct system 52 to the upflow drying station 30 to begin drying the material 26 entering the furnace 20. The preheated the air at the first cooling station 38, which is hotter, is directed to the heating and preheating stations 36 and 34 through a manifold 54 and the downcomers 56 descending from the collecting duct 52. Some of the preheated air, together with combustion products from the heating stations 36, is circulated through the downflow drying station 32 before passing through a gas treatment station 58 and on to a chimney 60.
As shown in, for example, Fig. 2, each of the downcomers 54 defines a vertical passage 61 for directing a downward flow 63 from collection channel 52 to a nearby heating station 36. Each of burners 44 is arranged to project a flame 65 more specifically, each of burners 44 is mounted on a downcomer wall 66 in a position to project the flame 65 in a direction extending across the vertical passage 61 toward the heating station 36 to provide heat for the reaction. which hardens the pelleted material 26.
Burner 44 in Fig. 2 is a self-priming burner which injects fuel and primary air at ambient temperature. Some of the preheated air from downflow 63 is drawn in by the fuel and primary air through an injector 68. The fuel, primary air, and drawn in air form a fuel-rich diffusion-like flame which propagates into the downflow 63, where the high abundance of air in the downward flow 63 results in an overall ratio which is very low in fuel, and thus with a high oxygen content. This propagation of a fuel-rich diffusion-like flame into a strongly heated overflow of combustion air produces high levels of interaction NOX when the unmixed or substandardly mixed fuel interacts with downflow air having a high temperature in a fuel-poor atmosphere with a large abundance of oxygen.
SUMMARY OF THE INVENTION A method and apparatus provides low-NOX combustion of fuel gas in a furnace combustion chamber. In the preferred embodiment, the furnace combustion chamber is a downcomer in a curing oven.
The process delivers fuel gas to the furnace combustion chamber from a premix burner having a reaction zone with an outlet to the furnace combustion chamber. This includes the steps of injecting a premix of primary fuel gas and combustion gas into the reaction zone, preferably injecting radial fuel gas into the reaction zone in a direction radially outward from an axis, and burning those reactants to provide combustion products containing reflux oxygen-rich oxygen. Further steps include separately injecting staged fuel gas into the oxygen-poor combustion air in the reaction zone, discharging the stepped fuel gas and oxygen-poor combustion air from the reaction zone through the outlet to the furnace combustion chamber, and burning the combustion fuel to the combustion gas. This makes it possible to achieve low-NOX combustion in the furnace combustion chamber as a result of interacting the stepped fuel gas with the oxygen-poor combustion air in the reaction zone.
The device comprises a burner structure defining a reaction zone with an outlet to the furnace combustion chamber. A mixing pipe 10 has an inlet connected to sources of primary fuel gas and combustion air, and has an outlet to the reaction zone. The device preferably further comprises a radial flame burner connected to sources of radial fuel gas and combustion air, and is arranged to be fired into the reaction zone. A stepped fuel injector is connected to a source of stepped fuel gas, and is arranged to inject the stepped fuel gas into the reaction zone separate from other injected reactants. Thus, the stepped fuel gas can interact with low oxygen combustion gas in the reaction zone to produce low NOX combustion in the furnace combustion chamber.
BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view of a pelletizing plant comprising a curing oven known from the prior art.
Fig. 2 is an enlarged partial view of parts of the curing oven in Fig. 1.
Figs. 3 and 4 are schematic views similar to those of Fig. 2, but showing embodiments of a curing oven which are not known from the prior art.
Figs. 5 to 8 are similar to Figs. 3 and 4, showing alternative embodiments of a curing oven.
Figs. 9 to 14 show other alternative embodiments of a curing oven with elements of the present invention.
DETAILED DESCRIPTION As partially shown in Fig. 3, a curing oven 100 is provided with burners 102, one of which is shown in the drawing. The furnace 100 also has a reactant supply and control system 104 for operating the burners 102. The furnace 100 is thus arranged according to the invention shown and claimed in co-pending US patent application 12 / 555,515, filed 09/02/2009, which is jointly owned by the applicant of the present patent application. The furnace 100 may otherwise be the same as the furnace 20 described above, with downcomers 110 defining vertical passages 111 for directing downward flow 113 from a collection duct to adjacent heating stations 114. As stated in the co-pending patent application, each of the burners 102 is mounted on a corresponding downcomer wall 116 in a position to project a premix flame 119 into the downstream flow 113 in the direction of the heating station 114. This provides heat for a reaction which cures the pelleted material 124 on a movable grid at the heating station 114.
In the illustrated embodiment, the flame 119 is pushed across the downcomer 110 toward a horizontal lower end section 125 of the vertical passage 111 terminating adjacent the heating station 114. Although the illustrated downcomer 110 has a predominantly vertical passage 111, any other suitable or combinations of different oriented passages to convey a preheated recirculation airflow to a core heating station are used.
The burners 102 are preferably arranged as premix burners with the structure shown in the drawings. This burner structure has a rear portion 140 which defines an oxidant chamber 141 and a fuel chamber 143.
The oxidant chamber 141 receives a stream of unheated atmospheric air from a blowing system 144. The fuel chamber 143 receives a stream of fuel from the natural gas plant supply 146.
Mixing tubes 148 are located within the oxidant chamber 141.
The mixing tubes 148 are preferably arranged in a circular arrangement centered on a longitudinal axis 149. Each of the mixing tubes 148 has an open inner end which receives a stream of combustion air directly from within the oxidant chamber 141. Each of the mixing tubes 148 also receives streams of fuel. from fuel lines 150 extending from the fuel chamber 143 into the mixing tube 148. These streams of fuel and combustion air flow through the mixing tubes 148 to form a combustible mixture known as a premix.
An outer portion 160 of the burner 102 defines a reaction zone 161 with an outlet port 163. The premix ignites in the reaction zone 161 as it exits the open outer ends of the mixing tubes 148.
Ignition is initially effected by means of an igniter before the reaction zone 161 reaches the self-ignition temperature of the premix.
Combustion proceeds when the premix is injected from the outlet port 163 adjacent the downcomer 110 to mix with the downflow 113. The fuel in the premix is then burned in a combustible mixture with both premix air and downflow air. By mixing the fuel with combustion air to form premix, the burner 102 avoids the production of interaction NOx that would occur if the fuel was unmixed or only partially mixed with combustion air before mixing into the downflow air.
As further shown in Fig. 3, the reactant inlets and control system 104 include a channel 180 through which the blower system 144 receives unheated air from the surrounding atmosphere. Another channel 182 extends from the blower system 144 to the oxidant chamber 141 at the burner 102. A fuel line 184 communicates the fuel source 146 with the fuel chamber 143 at the burner 102. Other parts of the system 104 include a controller 186, oxidant control valves 188, and fuel control valves 190.
The controller 186 has hardware and / or software arranged to operate the burner 102, and may include any suitable programmable logic controller or other controllable device, or combination of controllable devices, which are programmable or otherwise arranged to function as described and indicated. When the controller 186 executes the instructions, it operates valves 188 and 190 to initiate, control, and terminate flow of reactant streams that cause the burner 102 to fire a premix position 119 into the downcomer 110. The controller 186 is preferably arranged to operate the valves 188 and 190 as that the fuel and combustion air are supplied to the burner 102 in amounts which form a premix having a low fuel-to-oxidant ratio. The fuel-poor composition of premix helps prevent the production of interaction NOX in the downstream stream 113. Although the premix produces less interaction with NOX during combustion of the fuel-air mixture in the high temperature downstream stream 113, this has an efficiency consequence as it requires more fuel to heat. the atmospheric air in the premix. This efficiency gain can be reduced or avoided by means of an embodiment of the present invention which comprises preheated air in the premix. For example, in the embodiment shown in Fig. 4, the reactant inlets and the control system 104 include a duct 200 for supplying the burner 102 with preheated downflow air from the downcomer 110. As shown in the embodiment in Fig. 3, the control unit 186 in the embodiment of Fig. 4, preferably arranged to operate the arches 188 and 190 so that the fuel gas, the unheated air, and the preheated air are supplied to the burner 102 in amounts which form premix with a low fuel-to-oxidant ratio.
The embodiment of Fig. 5 also reduces the efficiency penalty caused by the premix in the embodiment of Fig. 3. In this embodiment, the reaction supply and control system 104 includes a fuel manifold 206 with a control valve 208. As schematically shown, the fuel manifold 206 terminates at a fuel injection port 210 as a separate injection port. downstream of the burner 102. The reaction supply and control system 104 are thus arranged to supply primary fuel gas and combustion air to the premix burner 102, and to separately inject the second stage fuel gas into the downcomer 110 without combustion air. The control unit 186 is preferably arranged to operate the valves 188, 190, 208 so that primary fuel and combustion air are supplied to the burner 102 in amounts which form premix with a low fuel-to-oxidant ratio, while at the same time supplying the branch line 206 with second stage fuel in an amount is stoichiometric with the premix provided to the burner 102. Since the premix in this embodiment comprises less than the total target rate of fuel, it may include a correspondingly smaller amount of unheated air to establish a low fuel-to-oxidant ratio. The smaller amount of unheated air in the premix causes a lower efficiency penalty.
A further NOX-suppressing feature of the invention is shown in Fig. 5 where the downcomer 110 is shown with a recessed wall portion 220. This portion 220 of the downcomer 110 defines a combustion zone 221 recessed from the vertical passage 111. The burner 102 is mounted on the recess of the downcomer 110. wall portion 220 for injecting premix directly into the vertical passage 111.
In the embodiment shown in Fig. 5, the premix flame 119 extends fully through the combustion zone 221 and into the vertical passage 111.
The control unit 186 could supply the burner 102 with fuel and combustion air at lower flow rates to cause the premix flame 119 to be only partially thrown through the combustion zone 221 and thereby produce less interaction NOX in the vertical passage 111. As shown in Figs. 6, a deeper combustion zone 225 can have the same effect without reducing reactant flow rates. Further suppression of interaction NOX can be accomplished with various incremental fuel injection openings along a recessed combustion zone. As shown in, for example, Fig. 7, these may include an opening 230 for injecting stepped fuel directly into the recessed combustion zone 225, an opening 232 for injecting stepped fuel directly into the vertical passage 111 upstream of the recessed combustion zone 225. and an opening 234 for injecting stepped fuel into the vertical passage 111 at a location downstream of the recessed combustion zone 225.
The embodiment of Fig. 8 has another alternative arrangement of stepwise fuel injector openings 236. These openings 236 are all arranged on the downcomer wall 116 in positions radially spaced from the burner opening 163, and are preferably arranged in a circular arrangement centered on a burner shaft shaft 149. includes a stepped fuel control valve 238 for diverting fuel to a manifold 240 which distributes the diverted fuel evenly to each port 236. The ports 236 together inject that fuel into the downcomer 110 in a circular array of other stepped streams. The openings 236 may be arranged to inject the second incremental fuel stream in directions parallel to and / or at an angle to the shaft 149.
The temperature of the preheated air in the downflow 113 is typically expected to be in the range of 1500 to 2000 degrees F, which is above the self-ignition temperature of the fuel gas. For natural gas, the self-ignition temperature is typically in the range of 1000 to 1200 degrees F.
Therefore, in the embodiments of Figs. 4-7, which use preheated downflow air together with ambient air to form premix with the fuel gas, the downflow air is mixed with the ambient air before it is mixed with the fuel gas. This cools the downflow air to a temperature below the self-ignition temperature to prevent the fuel from igniting inside the mixing tubes 146 before the premix enters the downcomer 110.
The pelletizing process typically requires temperatures closer to 2400 to 2500 degrees F. These process temperatures at the heating stations 114 could be provided by combustion with top low temperature 2500 to 2800 degrees F in nearby downcomers 110. These top low temperatures could be maintained by burning natural gas and preheated air. 1500-200 degrees F and 200% -600% excess air. Preheated air with that temperature and amount is available at the downflow 113. However, since the downflow air temperature at 1500-2000 degrees F is higher than the auto-ignition temperature, the downflow air can not form an ignited premix in the burners 102 unless first mixed with colder air as noted. above with respect to Figs. 4-7.
In the embodiment shown in Fig. 9, the furnace 100 includes an alternative premix burner 300. This burner 300 has many parts that are the same or substantially the same as corresponding parts of the burner 102 described above, and such parts are indicated by the same reference numerals in the drawings. The burner 300 thus has a rear portion 140 which defines an oxidant chamber 141 and a fuel chamber 143. The oxidant chamber 141 receives combustion air from the oxidant passage 182. The fuel chamber 143 receives fuel gas from the fuel line 184.
Like the burner 102, the burner 300 has mixing tubes 148 which are preferably arranged in a circular arrangement centered on a longitudinal axis 149. The mixing tubes 148 receive streams of combustion air from the oxidant chamber 141 and streams of fuel from fuel lines 150 reaching from the fuel chamber 143. 300 defines a reaction zone 161 having an outlet port 163 to the downcomer passage 111. The premix is injected from the open outer ends of the mixing tubes 148 into the reaction zone 161.
The burner 300 in Fig. 9 also includes a secondary fuel line 310 with an outlet port 311 centered on the shaft 149. The outlet port 311 is preferably provided as a high pressure nozzle, which may have any suitable configuration known from the prior art. The control unit 186 is arranged to operate a fuel supply valve 314 for the secondary fuel line 310 described above.
The burner 300 further includes a radial flame burner 320 concentrically located between the secondary outlet port 311 and the surrounding arrangement of mixing tubes 148. The radial flame burner 320 may function as a combustion anchor structure as described in U.S. Pat. U.S. Patent 6,672,862, which is incorporated herein by reference.
The radial flame burner 320 has a radial fuel line 322 which concentrically reaches over the secondary fuel line 310. A valve 324 supplies the radial fuel line 322 with fuel gas under the action of the control unit 186. As shown in the magnification of Fig. 9A, the outer end portion of the radial fuel line 322 fuel openings 325 which are directed radially outward. A radial combustion air passage 327 reaches concentrically over the radial fuel line 322. A spin plate 328 is located at the outer end of the passage 327, and a surrounding refractory surface 330 is tapered outwardly from the opening 327.
In operation of the embodiment of Fig. 9, a premix of primary fuel and primary combustion air is injected from the mixing tubes 148 adjacent to the reaction zone 161. Radial fuel is injected from the openings 325 into the reaction zone 161 in radially outward directions. Radial combustion air is injected from the passage 327 into the reaction zone 161 through the spin plate 328, which produces a vortex | which carries the radial fuel and the combustion air radially outwardly across the tapered refractory surface 330 against the injected streams premix. Combustion of these reactants in the reaction zone 161 then provides combustion products comprising oxygen-poor combustion air.
Secondary fuel is injected from the secondary fuel outlet port 311 in a jet which axially reaches across the reaction zone 161. The secondary fuel is mixed with the oxygen-poor combustion air in the reaction zone 161. Combustion continues as the contents of the reaction zone 161 move towards and through the outlet 16. the secondary fuel is mixed with oxygen-poor combustion air in the reaction zone 161 before interacting with the downflow 113, then less NOX is produced by further combustion of secondary fuel in the downflow 113 than it would have if the secondary fuel had been injected directly into the downflow 113 which described above with reference to the embodiments in Figs. 1-8.
The radial flame burner 320 will typically account for 1% to 3% of the total fuel supplied to the burner 300 except when the burner 300 fires at a high measuring range (typically 25% or less of maximum firing rate), in which case the proportion of the total fuel supplied by the radial flame burner 320 may be higher. In the best mode of operation, the proportion of the total fuel added to the premix, or primary, may be the fuel in a fuel-poor ratio of combustion air, and will result in a calculated premix adiabatic flame temperature in the range of 2600 ° to 3200 ° F. sufficient, when added to the primary and radial fuel as secondary fuel, to provide a stoichiometric ratio between the total fuel and the air supplied to the burner 10.
The control unit 186 may further be arranged to operate the burner 300 in Fig. 9 in a position in which a part of the secondary fuel is supplied to the radial flame burner 320 instead of the secondary fuel line 310.
The reaction zone 161 had then been provided with a total amount of fuel in four parts including some primary fuel at the mixing tubes 148, some fuel sufficient to perform the anchoring function at the radial flame burner 320, some secondary fuel also injected radially from the radial flame burner 320, and the remaining residue of the total amount as a portion of secondary fuel injected axially from the opening 311.
In the embodiment of Fig. 10, the curing oven 100 is equipped with a premix burner 400 which differs from the premix burner 300 in Fig. 9 by having a reaction zone 401 which is tapered radially outward, while the reaction zone 161 is tapered radially inward.
In the embodiment of Fig. 11, the curing oven 100 is equipped with a premix burner 600 that differs from the premix burner 300 of Fig. 9 by having multiple secondary fuel injectors 602, each of which is concentrically located within a respective mixing tube 148. Each mixing tube 148 is supplied with primary fuel by the premix lines 150 reaching from the premix fuel chamber 143. In the illustrated embodiment, the secondary fuel injectors 602 are supplied with fuel from a separate fuel chamber 604. A secondary fuel valve 606 is operated by the control unit 186 for the control unit 60. with secondary fuel separated from the primary fuel supplied to the premix fuel chamber 143.
The premix burner 700 in Figure 12 differs from the premix burner 600 in Figure 11 by having a reaction zone 705 which is tapered radially outward, while the reaction zone 161 in burner 600 is tapered radially inward.
The burner device 800 in Figure 13 includes a converging / diverging two-stage reaction zone 821 and one or more secondary fuel injectors 830. A portion of the fuel and all of the burner combustion air (except for a very small portion of the burner air supplied to the radial burner) are premixed in the mixing tube 14. as premix (also called primary fuel) will be in a fuel-poor ratio of burner combustion air, and will mostly burn in a primary combustion zone in reaction zone 821 converging sector 831. The products from the combustion of the poor premix will come from the converging sector 831, in the second, diverging step 833 of the reaction zone 830. The diverging section 833 of the reaction zone 821 may be arranged to minimize the entry of the furnace atmosphere with high oxygen content from the downcomer passage 111 by including a divergent taper at a 20 to 30 degree angle.
Secondary fuel can be introduced through the secondary fuel injectors 830 near the exit of the diverging section 833 of the reaction zone 821. This configuration will help minimize NOX by introducing the secondary fuel into the oxygen low combustion products from the premix fuel while helping to avoid high refractory temperatures. caused by combustion of near stoichiometric quantities of total fuel with preheated combustion air if the secondary fuel had been introduced into the converging zone 831 of the reaction zone 821.
This written description indicates the best mode of operation for carrying out the invention, and describes the invention for enabling the person skilled in the art to manufacture and use the invention, by presenting examples of elements recited in the claims. The patentable scope of the invention is defined by the claims, and may include examples other than those appearing to those skilled in the art. Such other examples, which may be available either before or after the filing date, are intended to be within the scope of the claims if they have elements which do not differ from the literal language of the claims, or if they have equivalent elements with insignificant differences from the literal language in patent claims.

权利要求:
Claims (36)
[1]
A method of effecting low NOx combustion of fuel gas in heated pelletizing process air, comprising: conveying pelleted material through a curing oven having a heating station and a passageway conducting heated process air to the heating station; drive heated process air through the passage in the direction of the heating station; and controlling a premix burner having a reaction zone with an outlet to the passage, comprising the steps of: injecting a premix of primary fuel gas and combustion air into the reaction zone; combining the premix to provide combustion products comprising oxygen-poor combustion air in the reaction zone; inject staged fuel gas into the reaction zone separate from the premix; discharging stepped fuel gas and oxygen-poor combustion air from the reaction zone through the outlet to the passage; and burning the stepped fuel gas and oxygen-poor combustion air in the heated process air in the passage, wherein low NOx combustion in the heated process air can be achieved as a result of interacting the stepped fuel gas with the oxygen-poor combustion air in the reaction zone.
[2]
The method of claim 1, wherein the premix is injected into the reaction zone in a low fuel state, wherein excess combustion air in the premix is available for oxygen reduction in the reaction zone.
[3]
The method of claim 1, wherein the reaction zone has a central axis, and stepped fuel gas is injected into the reaction zone as a jet centered around the axis. 10 15 20 25 30 15
[4]
The method of claim 1, wherein the stepped fuel gas is injected into the reaction zone from a high pressure nozzle.
[5]
The method of claim 1, wherein the premix is injected into the reaction zone of a mixing tube, and the stepped fuel gas is injected into the reaction zone of a stepwise fuel injector located in the mixing tube.
[6]
The method of claim 1, wherein the stepped fuel gas is injected into the reaction zone in a direction radially toward the axis.
[7]
A method of effecting low NOx combustion of fuel gas in a furnace combustion chamber, comprising: delivering fuel gas to the furnace combustion chamber from a premix burner having a reaction zone having an outlet to the furnace combustion chamber, comprising the steps of: blending and injecting into the reaction zone; injecting radial fuel gas into the reaction zone in a direction radially out of a shaft; burning the premix and the radial fuel gas to provide combustion products comprising oxygen-poor combustion air in the reaction zone; injecting stepped fuel gas into the reaction zone separate from the premix and the radial fuel gas; discharging stepped fuel gas and oxygen-poor combustion air from the reaction zone through the outlet to the furnace combustion chamber; and burning the stepped fuel gas and oxygen-poor combustion air in the furnace combustion chamber, wherein low NOx combustion in the furnace combustion chamber can be achieved as a result of interacting the stepped fuel gas with the oxygen-poor combustion air in the reaction zone. 10 15 20 25 30 16
[8]
The method of claim 7, wherein the premix is injected into the reaction zone in a low fuel state, wherein excess combustion air in the premix is available to reduce oxygen in the reaction zone.
[9]
The method of claim 7, wherein the stepped fuel gas is injected into the reaction zone as a jet centered around the axis.
[10]
The method of claim 7, wherein the stepped fuel gas is injected into the reaction zone from a high pressure nozzle.
[11]
The method of claim 7, wherein the premix is injected into the reaction zone of a mixing tube, and the stepped fuel gas is injected into the reaction zone of a stepwise fuel injector located in the mixing tube.
[12]
The method of claim 7, wherein the stepped fuel gas is injected into the reaction zone in a direction radially toward the axis.
[13]
Heated pelletizing process air, comprising: A method of effecting low NOx combustion in conveying pelleted material through a curing oven having a heating station and a passageway conducting heated process air to the heating station; drive heated process air through the passage in the direction of the heating station; and controlling a premix burner having a reaction zone with an outlet to the passage, comprising the steps of: injecting a premix of primary fuel gas and combustion air into the reaction zone; injecting radial fuel gas into the reaction zone in a direction radially out of a shaft; Incinerating the premix and the radial fuel gas in the reaction zone to provide combustion products comprising oxygen-poor combustion air in the reaction zone; injecting stepped fuel gas into the reaction zone separate from the premix and the radial fuel gas; discharging the stepped fuel gas and oxygen-poor combustion air from the reaction zone through the outlet to the passage; and burning the stepped fuel gas and oxygen-poor combustion air in the heated process air in the passage, wherein low NOx combustion in the heated process air can be achieved as a result of interacting the stepped fuel gas with the oxygen-poor combustion air in the reaction zone.
[14]
The reaction zone in a fuel-poor state, wherein excess combustion air in the Process of claim 12, wherein the premix is injected into the premix is available to reduce oxygen and to interact with the secondary fuel gas in the reaction zone.
[15]
The method of claim 12, wherein the stepped fuel gas is injected into the reaction zone as a jet centered around the shaft.
[16]
The method of claim 12, wherein the stepped fuel gas is injected into the reaction zone from a high pressure nozzle.
[17]
The reaction zone of a mixing pipe, and the stepped fuel gas. The method of claim 12, wherein the premix is injected into to be injected into the reaction zone from a stepwise fuel injector located in the mixing pipe.
[18]
The method of claim 12, wherein the stepped fuel gas is injected into the reaction zone in a direction radially toward the axis. 10 15 20 25 30 18
[19]
A heated pelletizing process air, comprising: An apparatus for effecting low NOX combustion in a curing oven structure defining a heating station, a conveyor belt conveying pelleted material to the heating station, and a passageway conducting heated pelletizing process air to the heating station; sources of primary fuel gas, combustion air, and stepped fuel gas; and a premix burner comprising: a structure defining a reaction zone having an outlet to the passage; a mixing pipe having an inlet which receives primary fuel gas and combustion air from the respective sources, and which has an outlet which discharges a premix of the primary fuel gas and combustion air into the reaction zone; and a stepwise fuel injector which receives stepped fuel gas from the respective source, and which injects the stepped fuel gas into the reaction zone separate from the premix, the stepped fuel gas being able to interact with oxygen-poor combustion air in the reaction zone to produce low NOx heat transfer process combustion.
[20]
The device of claim 19, wherein the reaction zone has a central axis, and the incremental fuel injector is centered on the axis.
[21]
The device of claim 19, wherein the stepwise fuel injector comprises a high pressure nozzle.
[22]
The device of claim 19, wherein the fuel injector is located in the mixing tube.
[23]
The device of claim 19, wherein the reaction zone comprises an inner end wall and a peripheral wall, and the stepwise fuel injector is located at a peripheral wall of the reaction zone. 10 15 20 25 30 19
[24]
The device of claim 19, wherein the reaction zone comprises a converging section into which the mixing tube and radial flame burner discharges reactants, and comprises a diverging zone including the outlet to the passage, and the stepwise fuel injector injects the stepped fuel gas into the reacting section diver.
[25]
An apparatus for effecting low NOx combustion of fuel gas in a furnace combustion chamber, comprising: sources of primary fuel gas, combustion air, radial fuel gas, and stepped fuel gas; a burner structure defining a reaction zone with an outlet to the furnace combustion chamber; a mixing tube having an inlet that receives primary fuel gas and combustion air from the respective sources, and has an outlet that discharges a premix of the primary fuel gas and combustion air into the reaction zone; a radial flame burner which receives radial fuel gas and combustion air from the respective sources, and which fires into the reaction zone; and a stepwise fuel injector which receives stepped fuel gas from the respective source, and which injects the stepped fuel gas into the reaction zone separate from the premix and the radial fuel, the stepped fuel gas being able to interact with oxygen-poor combustion air in the reaction zone to produce fuel for combustion. .
[26]
The device of claim 25, wherein the stepwise fuel injector is centered on a central axis of the radial flame burner.
[27]
The device of claim 25, wherein the stepwise fuel injector comprises a high pressure nozzle. 10 15 20 25 30 20
[28]
The device of claim 25, wherein the stepwise fuel injector is located in the mixing tube.
[29]
The device of claim 25, wherein the reaction zone comprises an inner end wall and a peripheral wall, and the stepwise fuel injector is located at a peripheral wall of the reaction zone.
[30]
The device of claim 25, wherein the reaction zone comprises a converging section into which the mixing tube and radial flame burner discharges reactants, and comprises a diverging zone comprising the outlet of the furnace combustion chamber, and the stepwise fuel injector injects the stepped fuel zone section gas into the stepped fuel zone.
[31]
An apparatus for effecting low NOx combustion in heated pelletizing process air, comprising: a hearth furnace structure defining a heating station, a conveyor belt conveying pelleted material to the heating station, and a passageway for conducting heated pelletizing process air to the heating station; sources of primary fuel gas, combustion air, radial fuel gas, and stepped fuel gas; and a premix burner comprising: a structure defining a reaction zone having an outlet to the passage; a mixing pipe having an inlet which receives primary fuel gas and combustion air from the respective sources, and which has an outlet which discharges a premix of the primary fuel gas and combustion air into the reaction zone; a radial flame burner which receives radial fuel gas and combustion air from the respective sources, and which fires into the reaction zone; and a stepwise fuel injector which receives stepped fuel gas from the respective source, and which injects the stepped fuel gas into the reaction zone separate from the premix and the radial fuel gas, the stepped fuel gas being able to interact with oxygen-poor combustion air in the reaction zone. -NOX combustion in the furnace combustion chamber.
[32]
The device of claim 31, wherein the stepwise fuel injector is centered on a central axis of the radial flame burner.
[33]
The device of claim 31, wherein the stepwise fuel injector comprises a high pressure nozzle.
[34]
The device of claim 31, wherein the stepwise fuel injector is located in the mixing tube.
[35]
The device of claim 31, wherein the reaction zone comprises an inner end wall and a peripheral wall, and the stepwise fuel injector is located at a peripheral wall of the reaction zone.
[36]
The device of claim 31, wherein the reaction zone comprises a converging section into which the mixing tube and radial flame burners discharge reactants, and comprises a diverging zone comprising the outlet to the passage, and the stepwise fuel injector injects the stepped fuel gas into the reacting section d.

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WO2015018438A1|2015-02-12|Burner assembly and method for combustion of gaseous or liquid fuel

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Cain et al.2012|Low NO x fuel injection for an indurating furnace

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同族专利:

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公开号 | 公开日

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US20130203003A1|2013-08-08|

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WO2013023116A1|2013-02-14|

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AU2012294314A1|2014-02-27|

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AU2012294314A8|2015-10-22|

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AU2012294314B8|2015-10-22|

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BR112014003143B1|2021-01-19|

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BR112014003143A2|2017-10-31|

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AU2012294314B2|2015-09-24|

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CA2844661A1|2013-02-14|

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法律状态:
2018-08-21| NAV| Patent application has lapsed|

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2018-09-18| NAV| Patent application has lapsed|

优先权:

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申请号 | 申请日 | 专利标题

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US201161521904P| true| 2011-08-10|2011-08-10|

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PCT/US2012/050245|WO2013023116A1|2011-08-10|2012-08-10|Low nox fuel injection for an indurating furnace|

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US13/571,424|US20130203003A1|2011-08-10|2012-08-10|Low NOx Fuel Injection for an Indurating Furnace|

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