WO2012141982A1 - Brûleur à faible tourbillon et à tirage naturel - Google Patents

Brûleur à faible tourbillon et à tirage naturel Download PDF

Info

Publication number
WO2012141982A1
WO2012141982A1 PCT/US2012/032526 US2012032526W WO2012141982A1 WO 2012141982 A1 WO2012141982 A1 WO 2012141982A1 US 2012032526 W US2012032526 W US 2012032526W WO 2012141982 A1 WO2012141982 A1 WO 2012141982A1
Authority
WO
WIPO (PCT)
Prior art keywords
fuel
burner
air
nox
flow
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/US2012/032526
Other languages
English (en)
Inventor
Robert K. CHENG
David Littlejohn
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
University of California Berkeley
University of California San Diego UCSD
Original Assignee
University of California Berkeley
University of California San Diego UCSD
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by University of California Berkeley, University of California San Diego UCSD filed Critical University of California Berkeley
Priority to US14/111,161 priority Critical patent/US20140230701A1/en
Publication of WO2012141982A1 publication Critical patent/WO2012141982A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • 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
    • F23D14/02—Premix gas burners, i.e. in which gaseous fuel is mixed with combustion air upstream of the combustion zone
    • F23D14/04—Premix gas burners, i.e. in which gaseous fuel is mixed with combustion air upstream of the combustion zone induction type, e.g. Bunsen burner
    • F23D14/08—Premix gas burners, i.e. in which gaseous fuel is mixed with combustion air upstream of the combustion zone induction type, e.g. Bunsen burner with axial outlets at the burner head
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
    • F23C6/00—Combustion apparatus characterised by the combination of two or more combustion chambers or combustion zones, e.g. for staged combustion
    • F23C6/04—Combustion apparatus characterised by the combination of two or more combustion chambers or combustion zones, e.g. for staged combustion in series connection
    • F23C6/042—Combustion apparatus characterised by the combination of two or more combustion chambers or combustion zones, e.g. for staged combustion in series connection with fuel supply in stages
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23B—METHODS OR APPARATUS FOR COMBUSTION USING ONLY SOLID FUEL
    • F23B5/00—Combustion apparatus with arrangements for burning uncombusted material from primary combustion
    • F23B5/02—Combustion apparatus with arrangements for burning uncombusted material from primary combustion in main combustion chamber
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
    • F23C9/00—Combustion apparatus characterised by arrangements for returning combustion products or flue gases to the combustion chamber
    • 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
    • F23D14/02—Premix gas burners, i.e. in which gaseous fuel is mixed with combustion air upstream of the combustion zone
    • F23D14/04—Premix gas burners, i.e. in which gaseous fuel is mixed with combustion air upstream of the combustion zone induction type, e.g. Bunsen burner
    • 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
    • F23D14/64—Mixing devices; Mixing tubes with injectors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
    • F23C2202/00—Fluegas recirculation
    • F23C2202/10—Premixing fluegas with fuel and combustion air
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
    • F23C2900/00—Special features of, or arrangements for combustion apparatus using fluid fuels or solid fuels suspended in air; Combustion processes therefor
    • F23C2900/06043—Burner staging, i.e. radially stratified flame core burners
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
    • F23C2900/00—Special features of, or arrangements for combustion apparatus using fluid fuels or solid fuels suspended in air; Combustion processes therefor
    • F23C2900/09002—Specific devices inducing or forcing flue gas recirculation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23D—BURNERS
    • F23D2900/00—Special features of, or arrangements for burners using fluid fuels or solid fuels suspended in a carrier gas
    • F23D2900/14—Special features of gas burners
    • F23D2900/14701—Swirling means inside the mixing tube or chamber to improve premixing

Definitions

  • the present invention is directed at energy efficient burners with minimal environmental impact.
  • This invention relates generally to gas burners, and more particularly to burners using fuel that is premixed with air or other oxidizers. Further this invention relates to the flame stabilization of gas burners and to burners that minimize the formation of oxides of nitrogen (NOAPP). Stabilized flame burners are used for many heating purposes, including process heating and heating of air and gas streams in ducts.
  • This invention relates to low swirl burners, and more particularly to an improved low swirl burner for low emission flames in which fuel pressure is utilized in a way that allows operation of the unit without the need of electric fans or blowers. Further this invention relates to natural draft burners. BACKGROUND OF THE INVENTION
  • the swirling flow pattern coming out of the device has a rotation in a plane normal to the axis of the flow.
  • This flow pattern can be described by a non-dimensional swirl number, S, which is defined as the ratio of axial flux of angular momentum to the axial flux of linear momentum divided b the nozzle radius.
  • Equation (1) where R is the burner radius, and U and w are the mean axial and tangential components, respectively, of the flow velocity exiting from the swirl generator.
  • the equation can be modified for cases in which the swirling action is generated by appropriately oriented jets or by mechanical vanes.
  • equation (1) reduces to:
  • R is the ratio of the radii of the central hub and the full swirler assembly
  • angle a is the exit angle of the swirl vanes relative to the bulk flow axis
  • m is the ratio of the mass of the nonswirling center flow to the mass of the outer swirling flow.
  • the rotating flow causes the gases to expand radially outward after leaving the exit tube of the device. This expansion causes a decrease in the axial velocity of the flow. There is a well-defined axial velocity gradient from the exit of the burner as the flow spreads out. Premixed air-fuel blends burn with well-defined flame speeds, and the flame will settle at the location where the velocity out of the burner matches the flame speed.
  • the characteristic flow pattern created by the low swirl burner provides an excellent flame stabilization mechanism.
  • Flashback The circumstance in which the flame front burns back to the exit port of the fuel line from the flame stabilization point.
  • Fuel mixture The mixture of one or more types of fuel.
  • Fuel-air mixture The mixture of one or more types of fuel combined with oxygen-containing fluid such as air, where said mixture provides the reactants for combustion.
  • Premixed burner A burner in which the fuel is mixed with air or oxygen- containing fluid before entering the flame zone.
  • Flame speed The rate at which flame reactants are consumed in combustion.
  • Blowout The circumstance in which the fuel mixture velocity exceeds the flame speed and thus extinguishes the flame.
  • Equivalence ratio Measures the departure from a stoichiometric combustion reaction. It is the ratio of fuel to available oxygen divided by the ratio of fuel to stoichiometric oxygen. It is designated by ⁇ p. For example, for methane,
  • Fuel rich conditions ⁇ > 1
  • Fuel lean conditions ⁇ ⁇ 1
  • Flame temperature The temperature of the hottest part of the flame.
  • Axial flow Flow that is parallel to the long axis of the burner body.
  • Radial flow Flow that is perpendicular to the long axis of the burner body.
  • Rotational flow Flow that rotates around the long axis of the burner body, in a plane normal to the axial fuel flow, also called tangential velocity.
  • a low swirl burner that can be powered by the fuel pressure alone, without the need for electric fans or blowers, while at the same time reducing residual oxygen content to 3% or less, along with low levels below 10 ppm NOx.
  • the energy stored in the fuel as a result of its pressurization is thus used to induce (entrain) air to flow along with it, and mix with the fuel.
  • the burner inlet geometry has been modified to entrain flue gas (exhaust gas) into the air-fuel mixture that feeds into the low swirl burner.
  • flue gas acts as a diluent to reduce flame temperature and thus NOx (nitrogen oxides) emissions produced by the flame. This allows the burner to operate more efficiently (at low excess air) while satisfying air quality regulations that limit release of NOx in the exhaust.
  • an air entrainment system driven by one or more jets of fuel either combined with a suitable mechanical swirler or configured with an appropriate geometry so as to create a well-mixed fuel-air blend and establish a flow pattern with an appropriate swirl number that is associated with the low swirl burner design.
  • One embodiment of the invention incorporates a jet-driven venturi matched to a vane swirler assembly.
  • the swirler configuration is configured to minimize the backpressure to the flow out of the venturi so as to maximize the velocity out of the burner assembly.
  • the swirler is also configured to optimize the non-dimensional swirl number associated with the exiting flow.
  • Another embodiment of the invention can incorporate multiple Venturis to feed the inlet of a single swirler. This configuration is similar to the design described above, with the additional advantage of having multiple Venturis to allow the assembly to be fabricated in a more compact fashion.
  • Another embodiment of the invention incorporates one or more fuel jets oriented axially and radially in such a manner to establish a suitable swirl number and the characteristic flow pattern of the low swirl burner at the exit.
  • the jet orientation may differ from the air jet orientation of the original low swirl burner design.
  • the fuel jets optionally feed Venturis to optimize air entrainment.
  • Another embodiment of the invention involves modification of an air amplifier (a device that uses the Coanda effect to increase the overall flow rate of the supply gas) with vanes or patterns in the interior wall, and optionally, a central structure, to establish a suitable swirl number and the characteristic flow pattern of the low swirl burner at the burner exit.
  • an air amplifier a device that uses the Coanda effect to increase the overall flow rate of the supply gas
  • Figure 1 illustrates a natural draft slow swirl burner apparatus according to an embodiment of the invention.
  • Figures 2a and 2b are a cross sectional views of two alternative designs for the natural draft low swirl burner of the invention.
  • Figures 3a and 3b are a cross sectional views of two additional alternative designs for the natural draft low swirl burner of the invention.
  • Figure 4 illustrates the burner heat output and NOx output as a function of exit velocity.
  • Figure 5 illustrates flame position versus bulk velocity out of burner.
  • Figure 6 illustrates the burner NOx output as a function of % excess air.
  • Figure 7 illustrates the burner NOx output as a function of % excess air for natural draft and forced draft conditions.
  • Figure 8 illustrates a modified lower backpressure swirler according to an embodiment of the invention.
  • Figure 9 illustrates that for a given fuel flow (heat output), the modified lower backpressure swirler provides higher air entrainment and higher bulk velocity using the same venturi and fuel injection orifice.
  • Figure 10 illustrates the dry NOx emissions of the LSB with the lower backpressure swirler as compared with the emissions of the LSB in the original configuration.
  • Figure 1 1 illustrates simulated dry NOx emissions, corrected to 3% oxygen, plotted against excess air.
  • Figure 12 illustrates actual dry NOx emissions, corrected to 3% oxygen, plotted against excess air.
  • Figure 13 illustrates actual dry NOx emissions for commercial and simple Venturis plotted against excess air.
  • Figure 14 illustrates a modified natural draft slow swirl burner apparatus including a circular tube with a number of small holes placed around an exit cone according to an embodiment of the invention.
  • Embodimenls of the invention describe a novel bumer-mixer apparatus which burns an ultra-lean premixed fuel-air mixture with a stable flame that operates without a mechanical fan or blower to flow air through the burner apparatus.
  • One embodiment of the invention utilizes fuel pressure to induce air flow though the burner assembly and achieve good mixing of the air and fuel prior to burning (hereafter referred to as a natural draft burner).
  • An embodiment of the invention also establishes a weak swirl, or low swirl, on the fuel-air flow.
  • the exit flow has a swirl number between about 0.01 and 3.0.
  • the fuel pressure supplies the energy to create a well-mixed flow of air, fuel, and optionally, a diluent, to exit the system with adequate velocity and the exit flow has rotation in a plane normal to the axial flow.
  • the flame burning in the exit region performs in the manner of a low swirl flame described in U.S. patents 5,735,681 and 5,879,148 incorporated herein by reference as if fully set forth in their entirety.
  • the low swirl burner is adaptable for a number of applications, including industrial heating, boilers, and gas turbines.
  • the low swirl concept has been adapted to natural draft operation, in which the fuel pressure, instead of an electrically powered fan or blower, induces air flow through the burner.
  • Natural draft burners are used at petroleum refineries and other sites where flammable materials are processed to avoid the hazard of electric spark generation.
  • the low swirl burner design offers ultra-low emissions as well as good fuel flexibility and turndown.
  • the low swirl design has been adapted to operate in a natural draft configuration.
  • the burner and mixer components have been sized and oriented appropriately to provide good mixing, suitable air-fuel ratio, adequate LSB exit velocity, and a low swirl flow pattern.
  • NOx production increases with flame temperature and the fuel-air ratio.
  • the flame temperature is sufficiently high such that more than 10 ppm NOx is produced.
  • a diluent can be added to the fuel-air mix to reduce NOx production while maintaining low excess oxygen in the exhaust.
  • Flue gas recirculation (FGR) is an example of an effective NOx control strategy using diluent addition.
  • Flue gas recirculation was incorporated into various embodiments of the natural draft burner design by adding a flow path for the burner flue gas to the LSB mixer inlet. By adjusting the effective areas for air and flue gas into the LSB inlet, up to 30% flue gas recirculation may be achieved.
  • the addition of FGR to the LSB design provided significant NOx reduction, and a range of conditions were identified that can satisfy the requirement of less than 10 ppm NOx at 3% oxygen in the exhaust.
  • a natural draft low swirl burner has been developed that is capable of achieving the NOx emissions requirements for refineries. Additional embodiments address scale-up, performance optimization, fuel switching, and insuring stable operation at the full range of environmental conditions.
  • One application of an embodiment of the invention is for process heating in petroleum refineries.
  • refineries use natural draft burners in their petroleum refining operations.
  • the existing burners are capable of switching between operation with natural gas and with hydrogen-containing refinery gas, but their NOx emissions exceed the levels necessary to satisfy upcoming limits that are being implemented by air pollution control districts, particularly in California.
  • the only currently-available method for refineries to satisfy the emissions limits promulgated by air quality management districts in California is to install post-combustion control systems such as selective catalytic reduction (SCR).
  • SCR selective catalytic reduction
  • Embodiments of the invention can be scaled up to a much larger heat output, and the components will be optimized for the operating conditions found at refineries.
  • Embodiments of the invention have been tested to insure that the design has adequate durability, reliability, and sufficient margin of safety over the entire range of potential operating conditions.
  • the natural draft low swirl burner design can also be applied to devices that currently use natural draft burners, either alone or with induced draft exhaust. Potential applications include boilers, water heaters, and residential and commercial furnaces. Burners for some of these appliances are relatively close in heat output to embodiments of the invention and therefore should not be difficult to adapt the design to these systems.
  • An embodiment of the low swirl burner (LSB) design is suitable for natural draft operation with 30 psig gaseous fuel. The emissions, turndown, and flame stability of the LSB have been assessed with natural gas and hydrogen-methane blends. The emissions have been compared with predicted emissions levels for premixed flames.
  • Flue gas recirculation and fuel staging, techniques for emissions reduction at low excess air, have been incorporated into the natural draft low swirl burner to demonstrate the capability of achieving significant emissions reductions at low excess air levels.
  • Embodiment 1 Demonstration of natural draft operation with a small scale LSB with at least 3:1 turndown using the following fuels:
  • the low swirl burner is an innovative burner design for premixed flames that utilizes a unique flame stabilization mechanism (Littlejohn and Cheng, 2007).
  • the design has been commercialized for process heating by
  • Maxon/Honeywell is under development for gas turbines, as well as adaptation for residential and commercial appliances.
  • burner apparatus 100 includes a venturi system 102 attached to the inlet of a 2 inch (5 cm) diameter low swirl burner 104.
  • the venturi 102 uses a 0.043 inch (0.1 1 cm) diameter fuel jet 106 to entrain air into the burner 100. Larger fuel jets were found to have insufficient air entrainment for good flame stability with 30 psig methane.
  • the venturi 102 has air inlets 108 on the side and bottom. The air inlets 108 can be partially blocked to decrease the air/fuel ratio.
  • the burner system 100 is also shown schematically in Figure 2a. Methane and hydrogen are supplied by standard gas cylinders at 30 psig, and fuel flows are measured with rotameters and/or mass flow meters.
  • Emissions measurements were performed by enclosing the flame with a quartz cylinder (not shown) to prevent dilution of the exhaust gas with outside air.
  • a continuous gas sample was collected at the top of the quartz cylinder, cooled and dried and flowed through a Horiba PG250 multi-gas analyzer.
  • the analyzer measures NOx, CO, CO2 and O2.
  • the analyzer was calibrated daily with calibration gases.
  • NOx (1 MMBlu / flame Btu)*(air flow/hr)*(meas. NOx conc.)*(46 g mole/454 g/lb)
  • CH4 + 2 0 2 C0 2 + 2 H 2 0 and to obtain a fixed level of excess air, the volume of fuel increases as the fraction of hydrogen in the fuel increases.
  • the diameter of the fuel injection 106 orifice was fixed for these initial studies, and it was difficult to obtain low excess air levels with 42% hydrogen-58% methane fuel blends since the higher volumetric flow created choked flow conditions at the orifice.
  • a larger orifice may be used to assess LSB performance at low excess air and high hydrogen fuel content.
  • the Horiba analyzer uses a NDIR (non-dispersive infra-red) detection system for carbon monoxide. This type of detector is subject to interference from other gases in the exhaust system, which can result in negative signals when the CO concentration is low.
  • NDIR non-dispersive infra-red
  • a Bendix model 8501 NDIR CO analyzer was used to confirm this observation.
  • a report by Jernigan et al (2002) from Thermo Environmental Instruments discusses potential interference in NDIR CO systems in more detail.
  • the flame stabilization mechanism of the low swirl burner 100 limits the minimum velocity at which the burner can operate.
  • the flame stabilization is a result of the gas velocity downramp that occurs as the gases flow out of the burner 100.
  • the flame front settles to the location where the air/fuel velocity matches the flame speed. If the velocity out of the burner is too low, the flame will propagate back into the burner and attach to the swirler body 104.
  • the swirler 104 will then act as a mechanical flame holder, similar to conventional burner designs.
  • Figure 5 which illustrates flame position versus bulk velocity out of burner.
  • U 0 represents the bulk velocity out of burner
  • the flame position is the height above the burner exit.
  • SL represents laminar flame speed. Flame speed is dependent on the composition of the fuel. For example, hydrogen has a higher flame speed than methane. As shown in the Figure 5, a flame with a higher flame speed will propagate into the burner at a higher exit velocity than a flame with a lower flame speed.
  • This information may be utilized for designing a low swirl burner system that will have stable operation with all fuel types and fuel flows that the system will experience. Burner manufacturers prefer to build in a safety margin so the burners can tolerate off-normal conditions.
  • Embodiment 2 Obtaining baseline NOx emissions from the same burner in forced draft operation.
  • Another embodiment seeks to improve the performance of the natural draft burner by incorporating a commercially available venturi and testing swirlers with lower backpressures.
  • Commercial Venturis have been optimized for operation with natural draft burners.
  • Swirler designs that have been adapted to reduce backpressure should allow operation at higher bulk velocities, which should expand the range of stable operation.
  • This embodiment expands the operating range of the natural draft low swirl burner.
  • the improved LSB system is utilized for the studies on flue gas recirculation and fuel staging described below.
  • Embodiment 3 Optimization of natural draft LSB to improve performance. Vary injection and pre ixing configuration to optimize natural draft burner to achieve the same emissions as forced draft. LSB Swirler Optimization
  • the low swirl burner under natural draft operation demonstrated emissions that were comparable to those obtained under forced draft operation.
  • the burner was close to the flashback limit at the lowest range of exit velocities studied. To allow for at least 3: 1 turndown while maintaining a good safety margin to avoid flashback, it is desirable to operate at higher velocities than those described above. There is a limited amount of energy in the 30 psig fuel to entrain air and push it through the burner assembly, so an efficient venturi premixer and a low backpressure LSB are needed to optimize system performance.
  • a lower backpressure swirler for the LSB has been designed and fabricated.
  • the new swirler has fewer vanes with a more aerodynamic profile to provide less backpressure.
  • An illustration of the lower backpressure swirler is shown in Figure 8.
  • the original swirler described above has 8 overlapping vanes and significantly more backpressure.
  • a screen or other flow restriction is used in the center section of the swirler to obtain the proper flow split between the non-swirling core flow and the swirling annular flow.
  • An equation has been developed to define a swirl number based on the flows and geometry of the LSB (Johnson et al, 2005).
  • a swirl number of - 0.5 has found to work well for most applications.
  • Several center screens were tested with the new swirler. Screens with little blockage reduce the LSB backpressure but can result in unstable flames. A center screen with 32% open area was found to provide good flame stability and relatively low backpressure.
  • the screen can be replaced with a tapered central body to reduce the potential for flame attachment to the swirler.
  • the optimum fuel injection orifice for the venturi will provide good air entrainment, good air/fuel mixing, and accommodate a range of fuel compositions.
  • a parametric study of fuel injection orifice sizes with the existing venturi was performed. Fuel injection orifices with holes equivalent to #57, #53, and #52 drill sizes were tested. For a given fuel flow rate, the smallest orifice generated the highest burner exit velocity. However, the larger orifices allow operation at higher heat outputs at a given fuel supply pressure. An excessively small orifice will limit the fuel flow to unacceptably low values, while an excessively large orifice may not create adequate fuel/air mixing. Fuel injectors with orifices in the range of #57 to #55 drill size provide the best performance in the current venluri-LSB configuration.
  • the fuel heat content per unit volume varies.
  • natural gas has over three times the energy content of hydrogen on a volumetric basis. Therefore, to maintain steady heat input into a burner, it is necessary to modulate the fuel flow in conjunction with the hydrogen content of the fuel.
  • the fuel injection orifice must be capable of delivering a range of fuel flow rates in response to fuel composition and heating needs while supplying well-mixed air and fuel to the burner.
  • Embodiment 4 Conduct of simulated FGR studies with natural draft LSB. Simulated FGR Studies
  • Embodiment 5 Testing of The LSB With A Commercial Venturi/Inspirator
  • a commercial venturi inspirator sized for ⁇ 100 kBtu h burners was obtained from Fives North American. It was coupled with the low swirl burner assemblies used in the earlier testing and operated over a range of conditions. The LSBs displayed good performance when fed by the commercial venturi. Dry NOx emissions were comparable to those obtained in the earlier experiments, as shown in Figure 13. The red and blue symbols represent earlier measurements obtained with the simple venturi, and the green symbols represent new data obtained with the commercial venturi. This also confirms that the simple venturi is achieving adequate air/fuel mixing. The data obtained with the commercial venturi are compiled in Table 6.
  • the commercial venturi has been optimized to entrain combustion air and achieve good mixing. This was demonstrated by the firing rates and burner exit velocities obtained in testing the low swirl burners. It was possible to operate at 10% higher flow rates than those obtained with the simple venturi system. This will translate into better turndown capability and better flame stability.
  • the commercial venturi also allows for finer adjustment of the air-fuel ratios by use of a threaded flange to control the air inlet gap width.
  • FGR flue gas recirculation
  • LSB low swirl burner
  • Another strategy to control NOx emissions from combustion is fuel staging.
  • a system with fuel staging uses a lean primary flame to limit initial NOx production. The remainder of the fuel is injected into the primary flame exhaust to consume some of the residual oxygen, and the exhaust from the system can have 3% oxygen or less. Since the secondary flame is burning vitiated (oxygen-depleted) air, it can have lower NOx emissions than if it burned in non-vitiated air.
  • a rich (oxygen-deficient) primary combustion zone is created, and then blend in air to achieve the desired overall stoichiometry.
  • Such burner systems are sometimes called RQL burners, for Rich- Quench-Lean combustion, or Rich-Quick mix-Lean combustion.
  • the rich primary zone has a relatively low flame temperature and consequently does not produce high NOx levels.
  • the rich primary zone can produce high levels of CO and unburned hydrocarbons since there is not sufficient oxygen for complete combustion.
  • the addition of secondary air lowers the overall stoichiometry to the desired level of excess air.
  • Methane-hydrogen fuel blends have higher flame speeds than methane alone and it will be more difficult to establish a fuel staging system for these blends that provides significant emissions reduction.
  • Embodiments of the invention demonstrate that FGR appears to be significantly more promising than fuel staging for controlling NOx emissions.
  • the flue gas recirculation system can be built into the natural draft low swirl burner assembly to minimize heat loss and to utilize the induced draft from the fuel injection. With the low back pressure associated with the low swirl burner, a 30 psig fuel stream has sufficient energy to entrain both combustion air and flue gas, and the system will be capable of achieving low emissions and good turndown.
  • Adding FGR to a natural draft LSB is a matter of incorporating a suitable flow path for flue gas to be entrained into the burner inlet with the combustion air. Dampers with low actuation force can be incorporated into the inlet air and flue gas flows to control the FGR rate.
  • the low swirl burner integrated with a suitable venturi, works well in natural draft configuration when fuel is available at ⁇ 30 psig. For best performance, a low pressure drop swirler should be matched with the designed flow output of the venturi.
  • the emissions of the natural draft low swirl burner agree well with the emissions predicted by Leonard and Stegmaier (1994).
  • the natural draft LSB works well with both natural gas and natural gas-hydrogen blends.
  • NOx emissions increase as the system excess air is reduced and flame temperature increases. It is desirable to operate refinery process heaters at low excess air conditions to improve efficiency.
  • Techniques such as flue gas recirculation (FGR) or fuel staging can lower NOx emissions from burners operating at low excess air conditions.
  • FGR flue gas recirculation
  • the natural draft low swirl burner was operated with simulated and actual FGR and with fuel staging.
  • the LSB with fuel staging did not show any improvement in NOx emissions over the unstaged natural draft LSB.
  • tests with simulated and actual flue gas recirculation indicated that the low swirl burner can achieve single digit NOx levels at low excess air when 20-30% FGR is utilized.
  • Embodiments of the invention demonstrate that the natural draft low swirl burner has the capability to achieve low emissions at low excess air conditions, and are adaptable to a commercial product for process heating.
  • Table I Natural draft operation of test LSB with emissions measurements (including turndown).
  • Table 2 Forced draft operation of test LSB with ei lissions measurements.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)

Abstract

L'invention porte sur une nouvelle conception d'un brûleur à faible tourbillon dans lequel on utilise le tirage naturel plutôt qu'une pompe à moteur pour entraîner un mélange combustible-air à travers le brûleur. Ce nouveau modèle permet de brûler un gaz dans des raffineries dans un environnement dans lequel des moteurs électriques ne pourraient pas être utilisés en raison du risque d'étincelles, qui pourraient déclencher des explosions. Des modifications additionnelles apportées au brûleur, y compris l'introduction de gaz usés dans le brûleur permet de réduire les gaz NOx afin de respecter les critères actuels de contrôle des émissions, sans avoir besoin de systèmes de contrôle des émissions après combustion.
PCT/US2012/032526 2011-04-13 2012-04-06 Brûleur à faible tourbillon et à tirage naturel Ceased WO2012141982A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US14/111,161 US20140230701A1 (en) 2011-04-13 2012-04-06 Natural draft low swirl burner

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US201161475159P 2011-04-13 2011-04-13
US61/475,159 2011-04-13

Publications (1)

Publication Number Publication Date
WO2012141982A1 true WO2012141982A1 (fr) 2012-10-18

Family

ID=47009649

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2012/032526 Ceased WO2012141982A1 (fr) 2011-04-13 2012-04-06 Brûleur à faible tourbillon et à tirage naturel

Country Status (2)

Country Link
US (1) US20140230701A1 (fr)
WO (1) WO2012141982A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103822231A (zh) * 2014-03-10 2014-05-28 北京华清燃气轮机与煤气化联合循环工程技术有限公司 一种燃气轮机低旋流燃烧室喷嘴
ITMI20130643A1 (it) * 2013-04-19 2014-10-20 Ergo Design S R L Bruciatore
CN112066371A (zh) * 2020-09-02 2020-12-11 西安交通大学 一种基于值班火焰的氢气预混低氮燃烧器

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8753111B2 (en) * 2011-10-06 2014-06-17 Lincoln Global, Inc. Swirl combustion air fuel torch
TW201437563A (zh) * 2013-03-22 2014-10-01 Shang-Yuan Huang 節能燃氣系統
CN104832928A (zh) * 2015-05-22 2015-08-12 遵义市节庆机电有限责任公司 甲烷燃烧装置
US10054310B2 (en) 2016-01-20 2018-08-21 Burning Point, L.C. Fast-heating outdoor gas burner apparatus and method
DE102016001893A1 (de) * 2016-02-17 2017-08-17 Eisenmann Se Brennereinheit und Vorrichtung zum Temperieren von Gegenständen
US11788722B2 (en) 2020-02-24 2023-10-17 The Regents Of The University Of California Flame stabilizer for natural draft lean premixed burner apparatus
US11835228B2 (en) * 2020-07-13 2023-12-05 Gastech Engineering Llc Cylindrical burner apparatus and method
CA3102511A1 (fr) 2020-12-11 2022-06-11 De.Mission Inc. Bruleur a combustion comprenant des aubes fixes
WO2024047123A1 (fr) * 2022-08-30 2024-03-07 Katholieke Universiteit Leuven Réacteur à effet tourbillonnaire

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4419074A (en) * 1981-09-11 1983-12-06 Advanced Mechanical Technology, Inc. High efficiency gas burner
US5735681A (en) * 1993-03-19 1998-04-07 The Regents, University Of California Ultralean low swirl burner
US20030175634A1 (en) * 2002-03-16 2003-09-18 George Stephens Burner with high flow area tip
US20070107437A1 (en) * 2005-11-15 2007-05-17 Evulet Andrei T Low emission combustion and method of operation

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5879148A (en) * 1993-03-19 1999-03-09 The Regents Of The University Of California Mechanical swirler for a low-NOx, weak-swirl burner

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4419074A (en) * 1981-09-11 1983-12-06 Advanced Mechanical Technology, Inc. High efficiency gas burner
US5735681A (en) * 1993-03-19 1998-04-07 The Regents, University Of California Ultralean low swirl burner
US20030175634A1 (en) * 2002-03-16 2003-09-18 George Stephens Burner with high flow area tip
US20070107437A1 (en) * 2005-11-15 2007-05-17 Evulet Andrei T Low emission combustion and method of operation

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ITMI20130643A1 (it) * 2013-04-19 2014-10-20 Ergo Design S R L Bruciatore
CN103822231A (zh) * 2014-03-10 2014-05-28 北京华清燃气轮机与煤气化联合循环工程技术有限公司 一种燃气轮机低旋流燃烧室喷嘴
CN103822231B (zh) * 2014-03-10 2017-11-03 北京华清燃气轮机与煤气化联合循环工程技术有限公司 一种燃气轮机低旋流燃烧室喷嘴
CN112066371A (zh) * 2020-09-02 2020-12-11 西安交通大学 一种基于值班火焰的氢气预混低氮燃烧器
CN112066371B (zh) * 2020-09-02 2021-06-22 西安交通大学 一种基于值班火焰的氢气预混低氮燃烧器

Also Published As

Publication number Publication date
US20140230701A1 (en) 2014-08-21

Similar Documents

Publication Publication Date Title
WO2012141982A1 (fr) Brûleur à faible tourbillon et à tirage naturel
CA2636767C (fr) Bruleur de combustible gazeux a faibles emissions d'oxydes d'azote
US5735681A (en) Ultralean low swirl burner
US5879148A (en) Mechanical swirler for a low-NOx, weak-swirl burner
US5470224A (en) Apparatus and method for reducing NOx , CO and hydrocarbon emissions when burning gaseous fuels
CN105164471B (zh) 贫方位角火焰燃烧器
EP2251605A2 (fr) Système de combustion à faible émission de NOx avec buse de combustible secondaire à injection directe prémélangée
US20080083224A1 (en) Method and apparatus for reducing gas turbine engine emissions
CN101813315A (zh) 用于燃气轮机燃烧器的同轴式燃料和空气预混合器
EP1303726A2 (fr) Ensemble de tubes venturi, et bruleurs et procedes utilisant ces ensembles
CN121532600A (zh) 燃烧器和操作方法
CN117571913A (zh) 面向工业锅炉的实验级氨煤燃烧试验系统及燃烧控制方法
CA2167320C (fr) Appareil et methode de reduction des emissions de nox, de co et d'hydrocarbures lors de la combustion de gaz
RU2230257C2 (ru) Устройство для сжигания газообразного топлива
JP4264003B2 (ja) 改良型燃焼排ガス循環を使用するバーナーシステム
KR20230118889A (ko) 고정 베인이 있는 연소 버너
RU2324117C1 (ru) Устройство для сжигания жидкого и/или газообразного топлива в газовой турбине
EP3717832B1 (fr) Ensemble brûleur à double carburant et procédé de fonctionnement d'un ensemble brûleur à double carburant
Nemitallah et al. Investigation of hydrogen-enriched methane oxy-combustion in a swirl-stabilized gas turbine combustor
Ramadan et al. Design Procedure of a Novel Micro-Turbine Low NOx Conical Wire-Mesh Duct Burner
AU2024324725A1 (en) Dual-fuel burner and method of operation
TW202507202A (zh) 燃燒器及操作方法
Kamal Innovative study of co-axial normal and inverse diffusion flames
Li et al. Experimental study of flow patterns and reaction in a multiple swirl spray combustor
Kim et al. Effect of a Multi Air-staged Burner on NO x Formation and Heat Transfer in Furnace Adopted the Reburning Process

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 12771574

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

WWE Wipo information: entry into national phase

Ref document number: 14111161

Country of ref document: US

122 Ep: pct application non-entry in european phase

Ref document number: 12771574

Country of ref document: EP

Kind code of ref document: A1