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US20020064738A1 - Method and apparatus for furnace air supply enrichment - Google Patents

Method and apparatus for furnace air supply enrichment Download PDF

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Publication number
US20020064738A1
US20020064738A1 US09/903,382 US90338201A US2002064738A1 US 20020064738 A1 US20020064738 A1 US 20020064738A1 US 90338201 A US90338201 A US 90338201A US 2002064738 A1 US2002064738 A1 US 2002064738A1
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United States
Prior art keywords
fuel
oxygen
flow rate
air
plenum
Prior art date
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Abandoned
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US09/903,382
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English (en)
Inventor
John Hugens
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American Air Liquide Inc
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American Air Liquide Inc
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Publication date
Application filed by American Air Liquide Inc filed Critical American Air Liquide Inc
Priority to US09/903,382 priority Critical patent/US20020064738A1/en
Assigned to AMERICAN AIR LIQUIDE, INC. reassignment AMERICAN AIR LIQUIDE, INC. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: HUGENS, JR., JOHN R.
Publication of US20020064738A1 publication Critical patent/US20020064738A1/en
Abandoned legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23D—BURNERS
    • F23D14/00—Burners for combustion of a gas, e.g. of a gas stored under pressure as a liquid
    • F23D14/46—Details
    • F23D14/60—Devices for simultaneous control of gas and combustion air
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23D—BURNERS
    • F23D14/00—Burners for combustion of a gas, e.g. of a gas stored under pressure as a liquid
    • F23D14/46—Details
    • F23D14/62—Mixing devices; Mixing tubes
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
    • F23L7/00—Supplying non-combustible liquids or gases, other than air, to the fire, e.g. oxygen, steam
    • F23L7/007—Supplying oxygen or oxygen-enriched air
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N1/00—Regulating fuel supply
    • F23N1/02—Regulating fuel supply conjointly with air supply
    • F23N1/022—Regulating fuel supply conjointly with air supply using electronic means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N5/00—Systems for controlling combustion
    • F23N5/18—Systems for controlling combustion using detectors sensitive to rate of flow of air or fuel
    • F23N5/184—Systems for controlling combustion using detectors sensitive to rate of flow of air or fuel using electronic means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N5/00—Systems for controlling combustion
    • F23N5/18—Systems for controlling combustion using detectors sensitive to rate of flow of air or fuel
    • F23N2005/181—Systems for controlling combustion using detectors sensitive to rate of flow of air or fuel using detectors sensitive to rate of flow of air
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N5/00—Systems for controlling combustion
    • F23N5/18—Systems for controlling combustion using detectors sensitive to rate of flow of air or fuel
    • F23N2005/185—Systems for controlling combustion using detectors sensitive to rate of flow of air or fuel using detectors sensitive to rate of flow of fuel
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2235/00—Valves, nozzles or pumps
    • F23N2235/02—Air or combustion gas valves or dampers
    • F23N2235/06—Air or combustion gas valves or dampers at the air intake
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E20/00—Combustion technologies with mitigation potential
    • Y02E20/34—Indirect CO2mitigation, i.e. by acting on non CO2directly related matters of the process, e.g. pre-heating or heat recovery

Definitions

  • the invention relates in general to air-oxygen-fuel combustion processes. More particularly, the invention relates to an enrichment system for a supply of air, and a method of enriching the supply of air practiced thereby, adapted for use with a combustion burner of a furnace, such as, for example, the type used in the production of molten metals.
  • a majority of combustion processes use air as an oxidizer to combust a fuel such as natural gas, fuel oil, methane, propane, waste oils, and other hydrocarbons and the like. It is known that the performance of many air-fuel combustion processes may be improved by enriching the combustion air with oxygen. Enrichment of the combustion air results in a hotter flame and generally more thermal efficiency since combustion energy is not wasted on heating a large amount of tramp nitrogen. The cost of using oxygen to enrich the combustion air may be offset by the gains in productivity from the enhanced combustion.
  • Furnace combustion burner designs that do not premix the combustion air and the fuel gas prior to the injection of the gases into the burner are known as nozzle mix or non-premix burners. These types of burners operate with a lower adiabatic flame temperature than that of a premix burner, and thus do not attain the thermal efficiency of premix burners.
  • the present invention provides a method and system for enhancing the supply of air delivered to a conventional premix or non-premix combustion burner assembly to increase productivity and thermal efficiency of the burner while minimizing changes to the nominal combustion ratio of the burner.
  • Oxygen and fuel are introduced into an air plenum upstream of the burner assembly in controlled quantities to form a nonflammable premix of pressurized air, fuel, and oxygen in the air plenum.
  • the air plenum has an outlet that communicates the nonflammable premix of pressurized gases to the conventional premix or non-premix burner for combustion.
  • the nonflammable premix of pressurized gases has a predetermined percentage level of oxygen and a predetermined percentage level of fuel.
  • the predetermined percentage level of fuel is selected so that the percentage level of fuel is less than that required to create a flammable premix in the air plenum.
  • a pressurized flow of air is directed into an air plenum of a furnace.
  • a supply of pressurized oxygen is passed into the air plenum via a first inlet port and a supply of pressurized fuel is passed into the air plenum via a second inlet port.
  • the pressurized air, oxygen and fuel mix together in the plenum to form the nonflammable premix of gases in which the percentage level of fuel present within the nonflammable premix is not sufficient to support combustion.
  • the premix of pressurized gases exit through an outlet port of the air plenum and which is in communication with the burner, which burner may be of a conventional premix or non-premix design.
  • the above-described method may also include the steps of measuring a flow rate of the air supplied to the air plenum and determining, based on the measured flow rate of air, the flow rate of oxygen and fuel required to provide the desired predetermined percentage levels of fuel and oxygen in the nonflammable premix.
  • the method may also include the steps of regulating the supply of oxygen and the supply of fuel entering the air plenum so that the percentage level of oxygen exiting the air plenum is maintained at the predetermined level of oxygen, and so that the percentage level of fuel exiting the air plenum is maintained at the predetermined level of fuel.
  • FIG. 1 is a schematic view of a conventional combustion burner assembly connected to a fuel plenum for carrying a pressurized flow of fuel therein, and an air plenum for carrying a pressurized flow of air therein, the fuel plenum and the air plenum in fluid communication with the combustion burner assembly.
  • FIG. 2 is a schematic view of a first embodiment of an enrichment system for mixing oxygen and fuel into the flow of air to form a nonflammable premix of gases in an air plenum.
  • FIG. 3 is a schematic view of a second embodiment of an enrichment system for mixing oxygen, fuel, and a heat absorber into the flow of air to form a nonflammable premix of gases in an air plenum.
  • FIG. 4 is a schematic view of a third embodiment of an enrichment system for mixing oxygen and fuel into the flow of air to form a nonflammable premix of gases in an air plenum, the oxygen and fuel passing into the air plenum via a first and a second critical orifice.
  • FIG. 1 a schematic representation of the supply of combustion air and fuel to a typical combustion burner assembly 4 of a furnace 2 is shown.
  • a fuel plenum 20 and an air plenum 10 are in fluid communication with a combustion burner assembly 4 .
  • the combustion burner assembly 4 is of a conventional type which may be, for example, a premix combustion burner assembly or a non-premix combustion burner assembly.
  • Both the fuel plenum 20 and the air plenum 10 are of the conventional type that is used to duct a pressurized flow of a gas.
  • the fuel plenum 20 carries a pressurized flow of fuel from a source of pressurized fuel, and has an outlet port 22 that is adapted to be in fluid communication with the combustion burner assembly.
  • the air plenum 10 carries a pressurized flow of combustion air A from a blower 16 or fan to an outlet port 12 that is adapted to be in fluid communication with the combustion burner assembly 4 .
  • the air plenum 10 can have multiple outlet ports 12 if, for example, the air plenum 10 supplies two or more combustion burner assemblies 4 .
  • the housing of a premix combustion burner assembly generally defines a premixing chamber 6 .
  • the outlet ports 12 , 22 of the air plenum 10 and the fuel plenum 22 respectively, are in communication with the premixing chamber 6 .
  • streams of gas exiting from the outlets 12 , 22 of the respective air and fuel plenums 10 , 20 pass into the premixing chamber 6 and are mixed together to form a flammable premixed combustion gas stream which is subsequently ignited to provide the flame for the burner assembly.
  • FIG. 2 a first embodiment of the enrichment system of the present invention is shown.
  • a portion of the air plenum 10 having a plurality of inlet ports 10 is shown.
  • the plurality of inlet ports 30 includes at least a first inlet port 31 and a spaced second inlet port 32 .
  • An oxygen supply plenum 50 and a separate fuel supply plenum 70 are connected to the air plenum 10 .
  • the oxygen supply plenum 50 is adapted to be in fluid communication with a supply of pressurized oxygen 52 for supplying pressurized oxygen to the air plenum 10 .
  • the oxygen supply plenum 50 has a distal end 54 that is connected to the first inlet port 31 of the air plenum 30 .
  • the fuel supply plenum 70 is adapted to be in fluid communication with a supply of pressurized fuel 72 for supplying of pressurized fuel to the air plenum 70 .
  • the fuel supply plenum 70 thus has a distal end 74 that is connected to the second inlet port 32 of the air plenum 10 .
  • the pressurized oxygen and the pressurized fuel together with the pressurized combustion air previously placed into the air plenum 10 , mix together to form a non-flammable premix of pressurized gases M.
  • the oxygen and the fuel are introduced into the air plenum at different points along the air plenum 10 .
  • the first and the second inlet ports 31 , 32 are spaced apart at least one air plenum diameter D apart, and more preferably at least four air plenum diameters apart, and still more preferably, at least seven air plenum diameters apart.
  • the first inlet port 31 be positioned upstream of the second inlet port 32 so that the introduced oxygen is mixed with the combustion air prior to the introduction of the fuel into the air plenum 10 .
  • the inlet ports 30 are therefore spaced proximate to the outlet port 12 of the air plenum 10 , and are thus proximate to the combustion burner assembly 4 .
  • both fuel and oxygen are added to the air plenum 10 in particular predetermined percentage levels.
  • the non-flammable premix of pressurized gases exiting the outlet port 12 of the air plenum 10 has a predetermined percentage level of oxygen and a predetermined percentage level of fuel.
  • the predetermined percentage level of oxygen is greater than the percentage of oxygen available in the supply of the combustion air because of the addition of the oxygen into the air plenum 10 .
  • the oxygen enrichment of the gases that are delivered to the combustion burner assembly 4 therefore serves to increase the thermal efficiency of the burner 4 .
  • the addition of the fuel to the non-flammable premix of gases in the air plenum 10 aids in preventing the combustion ratio at the burner 4 from becoming excessively fuel lean. Accordingly, the amount of readjustment required on the burner 4 is minimized while also at the same time the combustion efficiency of the burner 4 is being increased.
  • the predetermined percentage level of the fuel is less than that required to create a flammable premix in the air plenum 10 .
  • the premix of air, oxygen, and fuel supplied to the outlet port 12 of the air plenum 10 is non-flammable. Only upon the addition of additional fuel at the combustion burner assembly 4 , through the separate fuel plenum 20 , will a combustible mixture of gases be formed.
  • the first embodiment of the enrichment system may also include an air flow rate sensing device 80 for measuring the flow rate of the air flowing through the air plenum 10 upstream of the first inlet port 31 , a control device 90 for controlling the percentage levels of oxygen and fuel exiting the air plenum 10 , an oxygen regulating device 100 for regulating the supply of pressurized oxygen passed through the first inlet port 31 , a fuel regulating device 120 for regulating the supply of pressurized fuel passed through the second inlet port 32 , an oxygen feedback device 110 for adjusting the oxygen regulating device 100 so that the percentage level of oxygen exiting the air plenum 10 is maintained at the predetermined percentage level of oxygen, and a fuel feedback device 130 for adjusting the fuel regulating device 110 so that the percentage level of fuel exiting the air plenum 10 is maintained at the predetermined percentage level of fuel.
  • an air flow rate sensing device 80 for measuring the flow rate of the air flowing through the air plenum 10 upstream of the first inlet port 31
  • a control device 90 for controlling the percentage levels of oxygen
  • the air flow rate sensing device 80 generates an air flow rate output signal 82 based on the measured flow rate of the air in the air plenum 10 .
  • the air flow rate sensing device 80 may, for example, comprise a conventional flow rate sensor coupled to the air plenum 10 upstream of the first inlet port 31 .
  • power readings such as for example, blower amps, from the combustion air blower 16 may be used to determine the flow rate of the air in the air plenum 10 .
  • the oxygen regulating device 100 and the fuel regulating device 120 are operably coupled to the respective oxygen supply plenum 50 and the fuel supply plenum 70 .
  • Each regulating device is in fluid communication with a respective one or two inlet ports of the air plenum 10 and is adapted to regulate the flow of the supply of gas in fluid communication with its respective inlet port 30 .
  • each regulating device 100 , 120 comprises a regulator defining a passage (not shown) through which a gas traverses, and a flow controlling device (not shown) for adjusting the passage to change the rate of flow of the gas therethrough.
  • the respective oxygen and fuel feedback device 100 , 120 adjust the flow controlling device of at least one regulator, if necessary, so that the percentage level of oxygen and the percentage level of fuel exiting the air plenum 10 through the outlet gas port 12 is established and maintained at the predetermined percentage levels.
  • the regulator may be electrically actuated or pneumatically actuated, as known in the art. Further, the regulator may be a binary regulator, which is in either a fully open or a fully closed position, or, more preferably, a proportional regulator, in which the passage is opened in different amounts corresponding to the various desired flow rates.
  • the control device 90 is primarily responsive to the air flow output signal 82 .
  • the control device 90 establishes a determined oxygen flow rate from the oxygen supply plenum 50 and a determined fuel flow rate from the fuel supply plenum 70 which, when combined with the flow rate of the pressurized combustion air, will provide the predetermined percentage level of oxygen and the predetermined percentage level of fuel within the nonflammable premix of pressurized gases in the air plenum 10 .
  • the determined oxygen flow rate level and the determined fuel flow rate level are preferably continuously determined and updated to reflect any changes to the flow rate of the combustion air so that the determined oxygen and fuel flow rate levels are sufficient to provide the desired percentage compositional mix of air, oxygen, and fuel in the non-flammable premix of gases.
  • the control device 90 Based on the determination of the respective determined oxygen and fuel flow rates, the control device 90 generates an oxygen meter signal 102 and a fuel meter signal 122 .
  • the control device 90 comprises a processor or microprocessor electrically coupled to the air flow rate sensor or blower output that is used as the air flow rate sensing device 80 .
  • the control device 90 in response to the air flow rate output signal 82 , may, as a safety measure, also compare the flow rate of the air to a predetermined air flow rate level and generate the oxygen meter signal 102 and the fuel meter signal 122 only if the measured flow rate of the air is at least equal to the predetermined air flow rate level. This ensures that pressurized oxygen and pressurized fuel are not added to the air plenum 10 if an obstruction exists in the air plenum 10 or the combustion burner assembly 4 downstream of the inlet ports 30 within the air plenum 10 . Thus, a minimum flow rate of air through the air plenum 10 is ensured before pressurized oxygen and pressurized fuel are passed into the air plenum 10 .
  • the control device 90 controls the percentage composition of the nonflammable premix of gases exiting the outlet port 12 of the air plenum 10 by correcting the flow rate of oxygen and fuel entering the air plenum 10 through the first and second inlet ports 31 , 32 .
  • This control process occurs using the oxygen feedback device 110 and the fuel feedback device 130 , which are responsive to the oxygen meter signal 102 and the fuel meter signal 122 , respectively.
  • the oxygen feedback device 110 adjusts the oxygen regulating device 100
  • the fuel feedback device 130 adjusts the fuel regulating device 120 so that the percentage level composition of oxygen and the percentage level composition of fuel in fluid communication at the outlet port 12 of the air plenum 10 is maintained at the predetermined percentage levels.
  • each feedback device 110 , 130 comprises a driver circuit electrically coupled to the microprocessor and to its respective regulating device, e.g., the flow controlling device.
  • the oxygen feedback device 110 comprises a first driver circuit 112 coupled to the microprocessor and to the oxygen regulating device 100
  • the fuel feedback device 130 comprises a second driver circuit 132 coupled to the microprocessor and to the fuel regulating device 120 .
  • the first and second driver circuits 112 , 132 adjust the respective oxygen and fuel regulating device 100 , 120 based on electrical signal received from the microprocessor, thus varying the percentage level composition of oxygen and fuel within the air plenum 10 .
  • the first embodiment of the enrichment system may also include an oxygen flow rate sensing device 150 for measuring the flow rate of oxygen exiting the oxygen supply plenum 50 , and a fuel flow rate sensing device 170 for measuring the flow rate of fuel exiting the fuel supply plenum 70 .
  • the oxygen flow rate sensing device 150 is preferably disposed adjacent the distal end 54 of the oxygen supply plenum 50 and in fluid communication with the first inlet port 31 .
  • the oxygen flow rate sensing device 150 generates an oxygen flow rate output signal 152 based on the measured oxygen flow rate.
  • the fuel flow rate sensing device 170 is preferably disposed adjacent the distal end 74 of the fuel supply plenum 70 and in fluid communication with the second inlet port 32 .
  • the fuel flow rate sensing device 170 generates a fuel flow rate output signal 172 based on the measured fuel flow rate.
  • Each fuel and oxygen flow rate sensing device 150 , 170 preferably comprises a conventional flow rate sensor. However, any sensor that is capable of determining the flow rate of gas exiting the respective oxygen and fuel supply plenums 50 , 70 and providing a signal representative of the measured flow rate may by substituted for the respective oxygen flow rate or fuel flow rate sensors.
  • the microprocessor of the control device 90 is electrically coupled to the oxygen flow rate sensor that is used as the oxygen flow rate sensing device 150 and to the fuel flow rate sensor that is used as the fuel flow rate sensing device 170 .
  • the control device 90 compares the output of the oxygen flow rate sensing device 150 to the determined oxygen flow rate and generates an oxygen response signal 104 based upon this comparison. Further, the control device 90 compares the output of the fuel flow rate sensing device 170 to the determined fuel flow rate level and generates a fuel response signal 124 based upon this second comparison.
  • the control device 90 controls the percentage composition of the non-flammable premix of gases exiting the outlet port 12 of the air plenum 10 by correcting the flow rate of oxygen and fuel entering the air plenum 10 through the first and second inlet ports 31 , 32 . This control process occurs by using the oxygen feedback device 110 and the fuel feedback device 130 , which are responsive to the oxygen response signal 104 and the fuel response signal 124 , respectively.
  • the oxygen feedback device 110 adjusts the oxygen regulating device 100 and the fuel feedback device 130 adjusts the fuel regulating device 120 so that the flow rates of oxygen and fuel entering the air plenum 10 are maintained at the determined oxygen and fuel flow rates, which then allows the percentage level composition of oxygen and the percentage level composition of fuel in fluid communication with the outlet port 12 of the air plenum 10 to be maintained at the predetermined percentage levels.
  • a sonic flow rate sensor such as known in the art, coupled to the distal ends 54 , 74 of the respective oxygen and fuel supply plenums 50 , 70 may be a suitable substitute for the described oxygen and/or the fuel flow rate sensors.
  • Each sonic flow rate sensor defines a critical orifice (not shown) which is in fluid communication with the air plenum 10 .
  • the distal end 54 of the oxygen supply plenum 50 may define a first critical orifice 56 in fluid communication with the air plenum 10
  • the distal end 74 of the fuel supply plenum 70 may define a second critical orifice 76 which is in fluid communication with the air plenum 10 .
  • the critical orifices 56 , 76 serve to mix the respective gases within the air plenum 10 due to the pressure wave fronts that propagate from the critical orifices 56 , 76 proximate the air plenum 10 .
  • a pressurized flow of air is directed into the air plenum 10 of the furnace 2 .
  • the supply of pressurized oxygen is passed into the air plenum 10 via the first inlet port 31
  • the supply of pressurized fuel is passed into the air plenum 10 via the second inlet port 32 .
  • the pressurized air, oxygen, and fuel mix together in the air plenum 10 to form the nonflammable premix of gases M in which the percentage level of fuel present within the nonflammable premix is not sufficient to support combustion.
  • the premix of pressurized gases exits thought the outlet port 12 of the air plenum 10 towards the combustion burner assembly 4 .
  • the method may also include the steps of measuring a flow rate of the air supplied to the air plenum 10 and determining, based thereon, the flow rate of oxygen and fuel required to provide the desired predetermined percentage levels of fuel and oxygen in the nonflammable premix.
  • the method may also include the steps of regulating the supply of oxygen and the supply of fuel entering the air plenum 10 so that the percentage level of oxygen exiting the air plenum 10 is maintained at the predetermined level of oxygen, and so that the percentage level of fuel exiting the air plenum 10 is maintained at the predetermined level of fuel.
  • the steps of measuring and regulating occur continuously when the non-flammable premix of pressurized gases is being supplied to the outlet port 12 of the air plenum 10 .
  • the method may also comprise the steps of comparing the air flow rate output signal 82 to the predetermined flow rate level of the air, and only supplying pressurized oxygen and pressurized fuel to the air plenum 10 when the air flow rate output signal 82 is at least equal to the predetermined flow rate level of the air.
  • the method may also include the steps of monitoring the flow rate of oxygen and the flow rate of fuel entering the air plenum 10 , comparing the measured oxygen flow rate to the determined oxygen flow rate and the measured fuel flow rate to the determined fuel flow rate, and regulating the supply of oxygen and the supply of fuel entering the air plenum 10 so that the flow rate of oxygen supplied to the air plenum 10 is maintained at the determined oxygen flow rate and so that the flow rate of fuel supplied to the air plenum 10 is maintained at the determined fuel flow rate.
  • these monitoring, comparing, and regulating steps occur continuously.
  • the lower limit of flammability of methane in oxygen or air is approximately 4% at room temperature. Therefore, a mixture of less than approximately 4% methane in air or oxygen will not support combustion. So, by introducing methane into the air plenum 10 at a predetermined 3% level, which is less than that required to create a flammable premix in the air plenum 10 , and by introducing oxygen into the air plenum at a predetermined 6% level, the amount of oxygen available in the resulting nonflammable premix of pressurized gases is increased by approximately 28% and the available nitrogen is decreased by approximately 13%. Additionally, the combustion ratio of the combustion burner assembly 4 will remain generally constant due to the addition of the methane to the non-flammable premix.
  • FIG. 3 a second embodiment of the present invention is shown.
  • This embodiment further comprises a pressurized heat absorber plenum 180 , a heat absorber regulator 184 , and a heat absorber driver circuit 186 .
  • the heat absorber plenum 180 has a distal end 182 connected to a third inlet port 33 of the air plenum 10 for supplying a pressurized heat absorber, such as, for example, vaporized water, ammonia, and the like, to the air plenum 10 .
  • the third inlet port 33 may be positioned where desired on the air plenum 10 , but is preferably positioned adjacent the second inlet port 32 .
  • the heat absorber regulator 184 is operatively coupled to the heat absorber plenum 180 and is in fluid communication with the third inlet port 33 of the air plenum 10 .
  • the heat absorber driver circuit 186 is operably coupled to the microprocessor and the heat absorber regulator 184 so that the flow rate of heat absorber supplied to the air plenum 10 is maintained at a predetermined heat absorber rate.
  • the addition of heat absorber to the air plenum 10 acts to increase the lower limit of flammability of the non-flammable premix of gases in the air plenum 10 .
  • FIG. 4 illustrates a third embodiment of the enrichment system of the present invention.
  • the distal end 54 of the oxygen supply plenum 50 defines a first critical orifice 56 of known dimension and the distal end 74 of the fuel supply plenum 70 defines a second critical orifice 76 of known dimension.
  • Critical orifices are known to those skilled in the art, and allow for the sonic or near sonic passage of a predetermined flow rate of a gas from, in this instance, the respective oxygen and fuel supply plenums 50 , 70 to the air plenum 70 .
  • the critical orifices 56 , 76 also serve to mix the respective gases within the air plenum 10 .
  • pressurized oxygen at a predetermined pressure is supplied to the first critical orifice 56 and is passed therethrough and into the air plenum 10 at a predetermined fuel flow rate.
  • Pressurized fuel at a predetermined pressure is supplied to the second critical orifice 76 and is passed therethrough and into the air plenum 10 at a predetermined fuel flow rate.
  • the streams of the combustion air, oxygen, and fuel supplied to the air plenum 10 mix together to form the non-flammable premix stream of pressurized gases which is directed toward, and exits from the outlet port 12 of the air plenum 10 .
  • This embodiment of the enrichment system may also include the oxygen flow rate sensing device 150 for measuring the flow rate of oxygen exiting the oxygen supply plenum 50 , the fuel flow rate sensing device 170 for measuring the flow rate of fuel exiting the fuel supply plenum 70 , a control device 90 for controlling the percentage levels of oxygen and fuel exiting the air plenum 10 , the oxygen regulating device 100 for regulating the supply of pressurized oxygen passed through the first inlet port 31 , the fuel regulating device 120 for regulating the supply of pressurized fuel passed through the second inlet port 32 , the oxygen feedback device 110 for adjusting the oxygen regulating device 100 so that the percentage level of oxygen exiting the air plenum 10 is maintained at the predetermined percentage level of oxygen, and the fuel feedback device 130 for adjusting the fuel regulating device 120 so that the percentage level of fuel exiting the air plenum 10 is maintained at the predetermined percentage level of fuel.
  • the oxygen flow rate sensing device 150 for measuring the flow rate of oxygen exiting the oxygen supply plenum 50
  • the oxygen flow rate sensing device 150 is in fluid communication with the first critical orifice 56 and the fuel flow rate sensing device 170 is in fluid communication with the second critical orifice 76 .
  • a sonic flow rate sensor of conventional design may be a suitable substitute for the oxygen and fuel flow rate sensors because the critical orifice 56 , 76 is defined within the sonic flow rate sensor.
  • conventional flow rate sensors may be used, as previously discussed.
  • control device 90 is primarily responsive to the oxygen flow rate signal 152 and the fuel flow rate signal 172 .
  • the control device 90 compares the output of the oxygen flow rate sensing device 150 to a predetermined oxygen flow rate level and generates an oxygen response signal 114 based upon the comparison. Further, the control device compares the output of the fuel flow rate sensing device 170 to a predetermined fuel flow rate level and generates a fuel response signal 124 based upon the comparison.
  • the predetermined oxygen and fuel flow rate levels are based on a substantially constant and known flow rate of the combustion air and are sufficient to provide the desired percentage compositional mix of air, oxygen, and fuel in the non-flammable premix of gases.
  • the control device 90 preferably comprises a processor or microprocessor electrically coupled to the oxygen flow rate sensor and the fuel flow rate sensor that are used as the respective oxygen and fuel flow rate sensing devices 150 , 170 .
  • the control device 90 controls the percentage level composition of the non-flammable premix of gases exiting the outlet port 12 of the air plenum 10 by correcting the flow rate of oxygen and fuel entering the air plenum 10 through the first and second inlet ports 31 , 32 .
  • This control occurs using the oxygen feedback device 110 and the fuel feedback device 130 , each of which are responsive to the oxygen response signal 114 and the fuel response signal 124 , respectively.
  • the oxygen feedback device 110 adjusts the oxygen regulating device 100 and the fuel feedback device 130 adjusts the fuel regulating device 120 so that the flow rate of oxygen and fuel entering the air plenum 10 is maintained at the desired predetermined oxygen and fuel flow rates and so that the percentage level composition of oxygen and the percentage level composition of fuel in fluid communication with the outlet port 12 of the air plenum 10 are maintained at the predetermined percentage levels.
  • the third embodiment of the enrichment system may also include the air flow rate sensing device 80 for measuring the flow rate of the combustion air through the air plenum 10 upstream of the first inlet port 31 .
  • the air flow rate sensing device generates an air flow rate output signal 82 based on the measured flow rate of the air.
  • the control device 90 of the third embodiment may be responsive to the air flow rate output signal 82 to compare the flow rate of the air to a predetermined air flow rate level and generate the oxygen response signal 114 and the fuel response signal 124 if the measured flow rate of the air is at least equal to the predetermined air flow rate level.
  • a minimum flow rate of air through the air plenum 10 is ensured before pressurized oxygen and pressurized fuel are added to the combustion air within the air plenum 10 .

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Regulation And Control Of Combustion (AREA)
US09/903,382 2000-07-11 2001-07-11 Method and apparatus for furnace air supply enrichment Abandoned US20020064738A1 (en)

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US21783000P 2000-07-11 2000-07-11
US09/903,382 US20020064738A1 (en) 2000-07-11 2001-07-11 Method and apparatus for furnace air supply enrichment

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2834780A1 (fr) * 2002-01-11 2003-07-18 Air Liquide Four a dopage oxycombustible et dispositif de commande
US20080280239A1 (en) * 2004-11-30 2008-11-13 Richard Carroni Method and Device for Burning Hydrogen in a Premix Burner
US20110059408A1 (en) * 2008-03-07 2011-03-10 Alstom Technology Ltd Method and burner arrangement for the production of hot gas, and use of said method
US20110079014A1 (en) * 2008-03-07 2011-04-07 Alstom Technology Ltd Burner arrangement, and use of such a burner arrangement

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Publication number Priority date Publication date Assignee Title
US8246343B2 (en) 2003-01-21 2012-08-21 L'air Liquide Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Device and method for efficient mixing of two streams

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Publication number Priority date Publication date Assignee Title
US3199977A (en) 1962-06-22 1965-08-10 American Smelting Refining Method and apparatus for melting copper
US3299940A (en) 1963-06-22 1967-01-24 American Smelting Refining Burner structure
US4536152A (en) 1983-04-04 1985-08-20 Asarco Incorporated High-velocity gas burners
US4547150A (en) * 1984-05-10 1985-10-15 Midland-Ross Corporation Control system for oxygen enriched air burner
US5145361A (en) * 1984-12-04 1992-09-08 Combustion Research, Inc. Burner and method for metallurgical heating and melting
US5040470A (en) * 1988-03-25 1991-08-20 Shell Western E&P Inc. Steam generating system with NOx reduction

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2834780A1 (fr) * 2002-01-11 2003-07-18 Air Liquide Four a dopage oxycombustible et dispositif de commande
US20080280239A1 (en) * 2004-11-30 2008-11-13 Richard Carroni Method and Device for Burning Hydrogen in a Premix Burner
US7871262B2 (en) * 2004-11-30 2011-01-18 Alstom Technology Ltd. Method and device for burning hydrogen in a premix burner
US20110059408A1 (en) * 2008-03-07 2011-03-10 Alstom Technology Ltd Method and burner arrangement for the production of hot gas, and use of said method
US20110079014A1 (en) * 2008-03-07 2011-04-07 Alstom Technology Ltd Burner arrangement, and use of such a burner arrangement
US8459985B2 (en) * 2008-03-07 2013-06-11 Alstom Technology Ltd Method and burner arrangement for the production of hot gas, and use of said method
US8468833B2 (en) 2008-03-07 2013-06-25 Alstom Technology Ltd Burner arrangement, and use of such a burner arrangement

Also Published As

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WO2002004863A1 (fr) 2002-01-17

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