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Ultra-Low Emission Burner for High Efficiency Boilers and Furnaces Presentation to CIEE January 3, 2000.

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Presentation on theme: "Ultra-Low Emission Burner for High Efficiency Boilers and Furnaces Presentation to CIEE January 3, 2000."— Presentation transcript:

1 Ultra-Low Emission Burner for High Efficiency Boilers and Furnaces Presentation to CIEE January 3, 2000

2 Presentation Outline oLBNL’s Combustion Fluid Mechanics Research oBackground of low-swirl burner (LSB) and technology development history oProgress report on CIEE/DOE-OIT Multi-year Project o Scaling to > 10 MMBtu/hr and commercialization o Internal FGR development o Advanced 2 ppm NO x LSB concept o Laboratory demonstration in Sep. 01

3 Research Team oRobert K. Cheng *, Senior Scientist oIan G. Shepherd, Staff Scientist oDavid Littlejohn *, Staff Scientist oLarry Talbot, Prof. Mech. Eng., U.C. Berkeley oCarlo Castaldini *, Participating Guest & Consultant oScott E. Fable *, Senior Research Associate oAdrian Majeski *, Senior Research Associate oGary L. Hubbard *, Computer System Engineer oResearch Collaborators: o C. Benson * (ADLittle), B. Slim * (Gasunie), R. Srinivassen (Honeywell), C. K. Chan (H.K. Poly. U.), P. Greenberg (NASA Glenn), N. Peters (RWTH-Aachen), G. S. Samuelsen * (UC Irvine), J. Lee (Solo Energy), K. O. Smith (Solar Turbines) * participants of CIEE/DOE-OIT project

4 Mission oConduct research on combustion fluid mechanics to provide a basis for new and improved energy technologies that have minimum negative impact on the environment oTransfer basic knowledge to stationary heat and power generating systems

5 Motivations oFluid mechanical processes such as turbulence control combustion efficiency, flame stability, formation of pollutants and transition to detonation oTurbulent combustion theories and predictive numerical models rely on fundamental understanding of flame- turbulence interactions oAdvances in high efficiency and low emission combustion devices require fundamental knowledge of combustion fluid mechanics phenomena

6 Programmatic Objectives oElucidate fundamental fluid mechanical processes that control flame propagation rate, flowfield dynamics and overall flame behavior oBuild an experimental foundation for developing and validating theoretical models oTransfer knowledge to advance combustion technologies

7 Our Emphasis: Premixed Combustion oTheoretical Significance o Flame characteristics, flame speed and power density relate directly to turbulence scales and intensities o Flame dynamics couple to near-field and far-field conditions oImpact on Technology o Significant NO x reduction by lean burn (excess air combustion) o Important combustion technology for heat and power generation

8 Lean Premixed Combustion - Pollution Prevention Technology oLow NO x due to low flame temperatures o NO x (NO and NO 2 ) formation dominated by thermal generation o Premixed flame temperature can be set by equivalence ratio o No emission of particulate matter oChallenges for developing lean premixed systems o Stabilization, flame stability, noise, vibrations & safety o NO x -CO trade-off o Fuel flexibility o Scaling o Control

9 Projects Advanced Combustion System Flame Coupling With Its Environment NASA Microgravity Combustion Burner & Combustor Development Cal. Inst. of Energy Efficiency DOE-OPT Adv. Turbine Systems DOE-OIT Combustion LBNL LDRD Fundamental Flame Turbulence Interaction Processes DOE SC-Basic Energy Sciences LBNL LDRD

10 Recent Accomplishments oFundamental Studies o Designed an experiment to investigate flame structures under intense turbulence to support and verify new theory o Reconciled turbulent flame speed with burning rate o Identified near-field and far-field effects of buoyancy oTechnology Transfer and Development o Scaled low-swirl burner to industrial size (1 MW) o Demonstrated low-swirl injector for gas turbine

11 History of the Low-Swirl Burner oNovel stabilization concept for premixed flames o Discovered in 1991 o Swirl intensity about 1/10 of conventional swirl burners s Does not need recirculation to anchor flame o Exploits propagating nature of premixed combustion oFound to support very lean to very rich flames oConfirmed low emission under lean operation oDeveloped small LSB (15 TO 120 KW) for pool-heaters (DOE-LTR) oScaled LSB to 1 MW (CIEE Multi-year Project) oDemonstrated for gas turbine combustors

12 Principle of Flame Stabilization by Low-Swirl Fuel/Air mixture Propagating against the divergent flow, the flame settles where the local velocity equals the flame speed Small air jets swirl the perimeter of the fuel/air mixture but leave the center core flow undisturbed Flow divergence (generated by low- swirl) above the burner tube is the key element for flame stabilization

13 Current Status of LSB oTwo versions: o Jet-LSB for research and scaling o Vane-LSB for development and commercialization oScaled 3” burner to 1 MW (3.5 MMBtu/hr) o Demonstrated potential for scaling to 10 MMBtu/hr oCollaborating with commercial boiler OEMs oLicensing discussion with industrial burner OEMs oLaboratory demonstration of external FGR oLaboratory demonstration with partially reformed gas oLaboratory demonstration with low Btu gas firing

14 DOE ER-LTR Supported LSB Development for Water Heaters oInitiated technology development of LSB oDetermined effects of enclosure and orientation o Flame remains robust o Downward firing feasible oFound optimum operating condition o NO x < 10 ppm without compromising efficiency oDeveloped patented vane-swirler LSB fitted to a 15kW (50,000 Btu/hr.) Telstar Spa Heater Computer monitoring of efficiency and concentrations of NO, CO and O 2

15 Vane-Swirler Is The Critical Component Of LSB Technology oAir-jet swirler is deemed too complicated for most applications oNovel design feature centerbody with bypass and angled guide vanes to induce swirling motion in annulus oScreen balances pressure drops between swirl and center flows oUS Patent awarded 1999 Vane-swirler RhRh R  Screen Premixture Exit tube Top view of patented vane-swirler

16 CIEE 70K Exploratory Project to Evaluate LSB for Large Commercial Systems oIncrease laboratory burner dimensions by factor of 2 oTested three jet LSBs at LBNL and at UC Irvine Combustion Laboratory o 5 cm LSB in LBNL water heater simulator (12 to 18 kW) o 5 cm LSB in UCICL burner chamber (18 kW to 106 kW) o 10 cm LSB in UCICL furnace simulator (150 to 600 kW) o Demonstrate high firing rates o Determine swirl requirement and emissions 10 cm LSB 5 cm LSB

17 UCICL Furnace Simulator for Large (10.16 cm ID) Jet-LSB To emission analyzers REACTANT AIR IN

18 UCICL Burner Evaluation Facility for Small (5.28 ID) Jet-LSB

19 Comparison of Stability Regimes of Large and Small Jet-LSBs oResults verify constant velocity scaling for the LSB concept oIncrease in S g for scaled up LSB is proportional to increase in swirler recess distance L. This indicates constant residence time scaling.

20 Firing rate (kW) for the 5 cm LSB NO x ppm (3% O 2 ) 100200300400500 600 5 10 15 20 25 5075100125150 5 cm Burner 10 cm Burner Firing rate (kW) for 10 cm LSB NO x Independent of Burner Size and Input Power This 4” diameter low-swirl burner firing at 1.5 MMbtu/hr in a furnace simulator emits NO x = 12 ppm, CO = 20 ppm and HC < 1 ppm

21 High CO at low firing due to burner/furnace ineraction CO concentrations level-off to 25 ppm at higher firing. Firing rate (kW) for the 5 cm LSB 255075100125150 CO emissions in ppm (corr. to 3% O 2 ) Firing rate (kW) for the 10 cm LSB LOG SCALE 100200300400500600 1 10 100 1000 10000 5 cm, A c / A b = 15 5 cm, A c / A b = 142 10 cm, A c / A b = 733 Chamber Size Affects CO

22 UHC also depends on chamber/burner interaction. UHC drops below detectable limit at high firing 100200300400500600 0 25 50 75 100 125 Firing rate (kW) for the 10 cm LSB UHC emissions in ppm (corr. to 3% O 2 ) 2800 ppm at 17.5 kW 5 cm, A c / A b = 142 10 cm, A c / A b = 733 255075100125150 Firing rate (kW) for the 5 cm LSB UHC Limits Minimum Firing Rate

23 California Institute of Energy Efficiency Multi-Year Program (6/99 - 9/00) oLBNL 100K, UCICL 50K oResearch Develop and Demonstrate high capacity low-swirl burners up to 5 MMBtu/hr o Determine stable operating conditions for NO x < 10ppm, CO < 20 ppm, and high combustion efficiency o Develop scaling laws for vane-LSB o Continue development of vane-swirler for LSB with FGR o Develop guidelines for burner engineers to adapt LSB to fit different boilers and furnaces oPublished a paper in Transactions of the Comb. Inst. oLed to expanded research on LSB with partial steam reformed natural gas

24 Summary of Results 6-99 to 9-00 Pursue More-science-less-art approach to burner design and scaling

25 Parametric Study of Vane LSB oBurner radius, R oSwirler recess distance, L  Equivalence ratio,  oReference velocity oThermal input oSwirl number, S o For Jet-LSB R  - swirl jet radius, A  - total swirl jet area, m  - swirl air flowrate o For vane-LSB - developed new formula

26 oR = 2.63 and 3.8 cm, R h /R = 0.776  Eight thin guide-vanes with  = 37 o and 45 o oPerforated plate screens with 60, 65, 70, and 75 % blockage oL = 6.2 and 10 cm oDesigned and constructed LSBs with modular design for quick conversion Specifications of Two Vane-LSB Prototypes

27 Defining a Swirl Number  Separate integrals for core and annulus  Expressed in terms of mean axial velocities in the core, U c and in the annulus, U a  A simpler form expressed in terms of volumetric mass flow ratio being validated

28 Defining A Swirl Number for Vane-LSB oParameters:  Vane angle  o Ratio of burner to center body radiiR h /R = R o centerbody/annular of mass flux ratio  For the 7.68 cm ID LSi  = 37 o, R = 0.8 om can be estimated from effective area ratio

29 Velocity Measurement of Vane LSB Flowfield oComparison of Centerline Velocity Profiles of Jet- LSB and Vane-LSB to understand the foundation of flame stabilization -4 -2 0 2 4 6 8 10 0 20304050 Axial Distance (mm) U (m/s) Jet-LSB Vane-LSB -2 0 2 4 01020304050 Axial Distance (mm) U (m/s) Jet LSB Vane LSB U  = 2.5 m/s U  = 10 m/s

30 Determine LSB Performance With Different Screens and Swirl Numbers  with 65% screen,  at lean blow off is not a strong function of U  oVane-LSB design should have high turn-down Stable regime Blow-off

31 Tested Medium (7.68 cm ID) Vane-LSB in Boiler Simulator at Arthur D. Little Medium Vane-LSB o210 < Q < 280 kW  0.58 <  < 0.95 10 0 10 1 10 2 10 3 10 4 NO x ppm (3% O 2 ) CO ppm (3% O 2 ) 7.5 cm vane-LSB at 280 kW  = 0.95  = 0.58 Emission target area for new burners

32 LSB Demonstrated at 1 MW oExtensive testing of 7.6 cm LSB at UC Irvine Combustion Lab. Fuel Line Inlet Main Air Line Mounting Flange Premixer Fuel Line Inlet Main Air Line Refractory sleeve Premixer 14.5"

33 Emissions of vane-LSB match Best Available Control Technology oReached 1 MW thermal input and found lower NO x emissions with CO < 25 ppm and UHC below detectable limit 0.0 10.0 20.0 30.0 40.0 0.600.700.800.901.001.101.20 Equivalence Ratio,  NO x ppm (3% O 2 ) 0.18 MW 0.3 MW 0.6 MW 0.9 MW 1 MW LSB operating in UCICL furnace at 0.6 MW

34 Attributes of LSB for Furnace and Boiler Applications oSimple Low pressure drop design for ultra-lean premixed flames that is scalable to different capacities oAccepts different fuel types and fuel blends oHigh turndown (at least 60:1) oFlame does not hum oFlash back conditions can be predetermined oIgnites easily from either upstream or downstream oBurner does heat up during operation oFlame is not sensitive to enclosure or constriction oFurther NO x reduction with FGR

35 Laboratory Demonstration of LSB with External FGR o2” LSB with vane- swirler fitted to a Telstar heat exchanger oFlue gas drawn at the chimney oTested at 6 to 16kW with FGR up to 30% 1 10 100 1000 051015 NO x (3% O 2 ) CO (3% O 2 )  = 0.8  = 0.825  = 0.85  = 0.8  = 0.835 No FGR With FGR

36 Discovered Advanced 2 ppm NO x LSB Concept

37 Barriers and Constraints to Reaching < 2 ppm NO x oBurner stability near lean limits oHigh CO and HC emissions oFlame out and light off oSafety concerns oExcessive external FGR compromises efficiency oRequire precise control oLack of fuel flexibility and modulation capability

38 Combustion Scheme Based on Partial Reformed Gas oExploit combustion features of hydrogen enriched natural gas flames o Presence of OH radical suppresses CO the ultra-lean combustion conditions that deliver < 5 ppm NO x o H 2 lowers the lean flammability limit of natural/air combustion system thereby increasing the stability margin o Needs advanced lean premixed burner technology to capture these benefits

39 Steam Reforming C n H M + nH 2 O  nCO + (n + m/2) H 2  H = 226 kj/mole oProven Commercial Technology o Vendors for large and small reformers o Thermal recuperators demonstrated for gas turbines oTypical Industrial applications o Temperature = 1400 0 F (800 o C) o Ni-based catalyst active at 300 o C o Added water to maximize H 2 concentration oNeed research and development on partial reforming

40 LBNL Demonstration oFiring synthetic partially reformed gas with FGR at 60 kBtu/hr  Varied methane/air equivalence from 0.78 <  < 0.85 oVaried reformed gas ratio from 0 to 20% oVaried FGR from 0 to 30% oStable flame observed under all conditions with no flashback or blowoff oConfirm feasibility of LSB to implement this scheme

41 Burning of Partially Reformed Gas Lowers NO x and CO oWidens NO x -CO valley  NO x < 2 ppm, CO < 10 ppm at 0.75 <  < 0.8 with 23 % reformed gas  Needs to optimize  with percentage of partially reformed gas 1 10 100 1000 024681012 NO x (3% O 2 ) CO (3% O 2 ) 0% 10% 20% Reformed Gas

42 Overcoming Barriers oBurner stability near lean limits s H 2 in partially reformed gas improves lean stability limit oHigh CO and HC emissions s High OH radical pool leading to faster CO burnout oFlame out and light off s LSB with partially reformed gas is stable beyond current burner limits oSafety concerns s Burning of partially reformed gas expands the boundaries of operation, improves margin of safety oExcessive external FGR affects efficiency s Operate with lower excess air, while preserving low emission oTight control s LSB is resilient to rapid changes in mixture and flow conditions s Use of partially reformed gas further alleviates control needs oRigid/complex design s No change in LSB design seems necessary

43 CIEE/DOE-OIT Cost-Shared Program Launched in September 2000 oObjective: RD&D of commercial and industrial size LSBs with optional internal FGR capability that burn partial reformed natural to reach the ultimate performance target of 2 ppm NO x (3% O 2 ). oParticipants: CIEE Component: LBNL, CMC Engineering DOE-OIT Component: LBNL, A. D. Little oCurrent Funding Level: CIEE 300K, DOE-OIT 500K (FY01)

44 Overall Strategy oBuild upon CIEE Burner Research Effort oTwo synergistic cost-shared developmental programs o CIEE Component s Develop scaling methods for large industrial LSBs s Bench and pilot scale development of integrated partial reformer and LSB technologies o DOE-OIT Component s Conceptual design and evaluation of LSB with internal FGR and scale up to large industrial size oPlanned commercialization schedule < 25 ppm in 2001, < 5 ppm in 2003, < 2 ppm in 2007?

45 Planned Schedule

46 CIEE Component - Sep 00 to Sep 01 oLSB scaling and demonstration for large industrial systems oBench and pilot-scale development and demonstration of LSB with FGR and partial reformer oTasks: o Scale-up and testing of LSB with FGR at UCICL (LBNL) o Computational modeling of reformer kinetics (LBNL, CMC) o Engineering analysis of reformer design, heat transfer and operation and bench-scale simulation testing with LSB (CMC, LBNL) o Commercialization of basic LSB for industrial applications

47 DOE-OIT Component - Oct 00 to Sep 01 oDevelopment, design, scale-up, and evaluation of LSB with internal FGR capability oIntegration of LSB to commercial and industrial systems oTasks: o Determine optimum operating conditions for LSB with FGR and partially reformed natural gas (LBNL) o Design develop and evaluate premixer to enable internal FGR in LSB systems (ADLittle) o Demonstrate LSB with internal FGR to 2 MMBtu/hr (ADLittle/LBNL)

48 CIEE Component - Oct 01 to Sep 02 oDemonstration of partial reformer concept for industrial systems at pilot scale oTasks: o Select demonstration site and defining demonstration target (LBNL/OEM) o Bench scale partial reformer fabrication and assembly (CMC) o Economic and market assessment of ultra-low NO x systems (CMC/LBNL) o Secure commercial manufacturing agreement and licensing for large industrial 5 ppm NO x natural gas fired LSBs (LBNL)

49 DOE-OIT Component - Oct 01 to Sep 02 oScale up of LSB with internal FGR to > 10 MMBtu/hr oDevelopment of large LSB for internal FGR and optimized for partial reformed gas operation oPlan pilot scale testing of internal FGR LSB with demonstration partner oTasks: o Develop scaling parameters for LSBs with partial-reformed- gas and internal FGR capabilities (LBNL) o Perform pilot scale testing (LBNL, ADLiltte, OEM)

50 Progress Report 10-00 to 1-01

51 Commercialization of Vane-LSB for Industrial Applications oDevelopment and commercialization partners o Aerco International - packaged boilers < 2 MMBtu/hr s demonstrated on-site o Vapor Corporation - packaged steam boilers < 5 MMBtu/hr s demonstrated in-boiler, product development in progress o Maxon Corporation - industrial burners < 20 MMBtu/hr s demonstrated on-site, prototype developed, licensing discussion o Eclipse Combustion - process heat burners < 10 MMBtu/hr s on-site demonstration in progress o Gasunie - water heaters < 15 MMBtu/hr s collaboration discussion, interested in scaling to 6” i.d. o Coen Company - industrial burners s initial information exchange and discussion

52 Demonstrated Power Capacity of Low Swirl Stabilization Method UCICL Solar Turbines Solo Energy

53 Scale-up and testing of LSB with External FGR at UCICL oPlanned testing in UCICL boiler simulator o Facility commissioned in Oct. 2000 o Available for LSB testing in first quarter of 2001 oTest plan for 3” vane-LSB o push firing rate to 5 MMBtu/hr  explore emissions and efficiency with FGR at different  s o optional velocity measurements oTest plan for larger vane-LSB o UCICL Boiler simulator limited to < 5 MMBtu/hr o Construction and testing of 4” to 6” LSBs will depend on commercialization partners’ interests and plans

54 Engineering Analysis of Reformer Design, Heat transfer and Operation Premixed Burner Main Radiant furnace Convective section of furnace Stack Nat. gas + flue gas + reformed gas Steam Reformer Path of flue gas Recirculated flue gas Steam Combustion air Fan Natural gas Flue gas oConceptual system design for industrial process heat

55 DOE-OIT Supported Tasks ON Performance Criteria of LSB with Partially Reformed Gas oOptimization of H 2 /CO concentration and equivalence ratio to meet design goals (i.e. < 5 ppm NO x and < 10 ppm CO, no UHC) oEffects of steam addition to hardware oCombustion stability of flame with H 2 enrichment and steam injection oOptimization of burner to accept different ratios of FGR, reformed gas, equivalence ratio for large and small systems

56 CIEE Supported Technical Development Plan For Partial Reformer oIntegrated heat transfer to reformer oConversion performance at low catalyst temperature oEffects of variation in gas composition oMinimum steam requirements oDurability testing of catalyst oReactor size and volume oCatalyst resistance to sulfur oOptimize design to prevent carbon formation


58 Technology Assessment for Partial Reformer oCOMPLETED REFORMER TECHNOLOGY SURVEY AND ASSESSMENT: o Literature search to identify NiO as the efficient reform catalysts that will be resistant to poisoning from sulfur in natural gas o Energy requirement for reforming can be offset by burner and boiler efficiency improvements o Reactor in reformer sizing tradeoffs with H 2 output, cost, and hardware integration o Commercial interest in technology approach for flame stability oLOCATED HARDWARE SUPPLIERS AND ESTABLISHED COMMERCIAL SMALL-SCALE SUPPORT o Corning, Sud-Chemie, and Fraunhofer Institut contacted and expressed interest to collaborate

59 Progressing Towards Laboratory Demonstration oDeveloping an existing burner stations in 70-141 for testing the LSB with synthetic reform gas and FGR o Eventual use with a bench-scale reformer prototype with in situ FGR oDeveloping a reform catalyst testing and evaluation facility o Will evolve into a bench-scale reformer for use with the LSB oDeveloping computer controlled monitoring systems o Small oven for steam generation and monitoring o Electronic flow controllers for generation of simulated FGR and reformer gases

60 Computational Modeling of Reformer Kinetics oCompleted Perfectly Stirred Reactor (PSR) analysis using Chemkin chemical kinetic model o Employed GRI-Mech 3.0 nitrogen chemistry o Confirmed benefit of H 2 addition to reduce CO at extremely lean conditions o Effects of FGR on lowering NO x confirmed oWill use Chemkin to optimize the amount of partial reformed gas needed to address tradeoff of performance and cost o Compare with laboratory results to be obtained from DOE-OIT effort oResults needed to verify scale up efforts for highly premixed lean industrial flames

61 Demonstration to CIEE and DOE- OIT in Sep 2001 oBench-scale validation of LSB operating with FGR and a partial reformer concept prototype at LBNL

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