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Ultra-Low Emission Burner for High Efficiency Boilers and Furnaces

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Presentation on theme: "Ultra-Low Emission Burner for High Efficiency Boilers and Furnaces"— Presentation transcript:

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

2 Presentation Outline LBNL’s Combustion Fluid Mechanics Research
Background of low-swirl burner (LSB) and technology development history Progress report on CIEE/DOE-OIT Multi-year Project Scaling to > 10 MMBtu/hr and commercialization Internal FGR development Advanced 2 ppm NOx LSB concept Laboratory demonstration in Sep. 01

3 Research Team Robert K. Cheng*, Senior Scientist
Ian G. Shepherd, Staff Scientist David Littlejohn*, Staff Scientist Larry Talbot, Prof. Mech. Eng., U.C. Berkeley Carlo Castaldini*, Participating Guest & Consultant Scott E. Fable*, Senior Research Associate Adrian Majeski*, Senior Research Associate Gary L. Hubbard*, Computer System Engineer Research Collaborators: 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 Conduct research on combustion fluid mechanics to provide a basis for new and improved energy technologies that have minimum negative impact on the environment Transfer basic knowledge to stationary heat and power generating systems

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

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

7 Our Emphasis: Premixed Combustion
Theoretical Significance Flame characteristics, flame speed and power density relate directly to turbulence scales and intensities Flame dynamics couple to near-field and far-field conditions Impact on Technology Significant NOx reduction by lean burn (excess air combustion) Important combustion technology for heat and power generation

8 Lean Premixed Combustion - Pollution Prevention Technology
Low NOx due to low flame temperatures NOx (NO and NO2) formation dominated by thermal generation Premixed flame temperature can be set by equivalence ratio No emission of particulate matter Challenges for developing lean premixed systems Stabilization, flame stability, noise, vibrations & safety NOx-CO trade-off Fuel flexibility Scaling Control

9 Projects Fundamental Flame Turbulence Interaction Processes
DOE SC-Basic Energy Sciences LBNL LDRD 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

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

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

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

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

14 DOE ER-LTR Supported LSB Development for Water Heaters
Initiated technology development of LSB Determined effects of enclosure and orientation Flame remains robust Downward firing feasible Found optimum operating condition NOx < 10 ppm without compromising efficiency Developed 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 O2

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

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

17 UCICL Furnace Simulator for Large (10.16 cm ID) Jet-LSB
To emission analyzers REACTANT AIR IN screens honeycomb air swirl air 80 cm fuel L premixing zone 10.16 cm

18 UCICL Burner Evaluation Facility for Small (5.28 ID) Jet-LSB
reactant air 5.28 cm fuel screens 40 cm premixing zone swirl air L

19 Comparison of Stability Regimes of Large and Small Jet-LSBs
Results verify constant velocity scaling for the LSB concept Increase in Sg for scaled up LSB is proportional to increase in swirler recess distance L. This indicates constant residence time scaling. 4 8 12 16 20 24 28 0.00 0.02 0.04 0.06 0.08 0.10 0.12 U, reference velocity (m/s) Geometric Swirl Number , Sg 106 kW 18 kW 146 kW 585 kW Stable Unstable 5 cm 10 cm

20 NOx Independent of Burner Size and Input Power
Firing rate (kW) for the 5 cm LSB NOx ppm (3% O2) 100 200 300 400 500 600 5 10 15 20 25 50 75 125 150 5 cm Burner 10 cm Burner Firing rate (kW) for 10 cm LSB This 4” diameter low-swirl burner firing at 1.5 MMbtu/hr in a furnace simulator emits NOx = 12 ppm, CO = 20 ppm and HC < 1 ppm

21 Chamber Size Affects CO
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 25 50 75 100 125 150 CO emissions in ppm (corr. to 3% O2) Firing rate (kW) for the 10 cm LSB LOG SCALE 200 300 400 500 600 1 10 1000 10000 5 cm, Ac / Ab = 15 5 cm, Ac / Ab = 142 10 cm, Ac / Ab = 733

22 UHC Limits Minimum Firing Rate
100 200 300 400 500 600 25 50 75 125 Firing rate (kW) for the 10 cm LSB UHC emissions in ppm (corr. to 3% O2) 2800 ppm at 17.5 kW 5 cm, Ac / Ab = 142 10 cm, Ac / Ab = 733 150 Firing rate (kW) for the 5 cm LSB UHC also depends on chamber/burner interaction. UHC drops below detectable limit at high firing

23 California Institute of Energy Efficiency Multi-Year Program (6/99 - 9/00)
LBNL 100K, UCICL 50K Research Develop and Demonstrate high capacity low-swirl burners up to 5 MMBtu/hr Determine stable operating conditions for NOx < 10ppm, CO < 20 ppm, and high combustion efficiency Develop scaling laws for vane-LSB Continue development of vane-swirler for LSB with FGR Develop guidelines for burner engineers to adapt LSB to fit different boilers and furnaces Published a paper in Transactions of the Comb. Inst. Led 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
Burner radius, R Swirler recess distance, L Equivalence ratio, f Reference velocity Thermal input Swirl number, S For Jet-LSB R - swirl jet radius, A - total swirl jet area, m - swirl air flowrate For vane-LSB - developed new formula

26 Specifications of Two Vane-LSB Prototypes
R = 2.63 and 3.8 cm, Rh/R = 0.776 Eight thin guide-vanes with a = 37o and 45o Perforated plate screens with 60, 65, 70, and 75 % blockage L = 6.2 and 10 cm Designed and constructed LSBs with modular design for quick conversion

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

28 Defining A Swirl Number for Vane-LSB
Parameters: Vane angle a Ratio of burner to center body radii Rh/R = R centerbody/annular of mass flux ratio For the 7.68 cm ID LSi a = 37o, R = 0.8 m can be estimated from effective area ratio

29 Velocity Measurement of Vane LSB Flowfield
4 10 U= 2.5 m/s U= 10 m/s 2 8 U (m/s) Jet-LSB Vane-LSB Jet LSB 6 Vane LSB -2 4 U (m/s) 10 20 30 40 50 Axial Distance (mm) 2 Comparison of Centerline Velocity Profiles of Jet-LSB and Vane-LSB to understand the foundation of flame stabilization -2 -4 10 20 30 40 50 Axial Distance (mm)

30 Determine LSB Performance With Different Screens and Swirl Numbers
0.5 0.6 0.7 0.8 0.9 1.0 2 4 6 8 10 12 14 Reference velocity U (m/s) f at lean blow-off 60% 65% 70% 75% with 65% screen, f at lean blow off is not a strong function of U Vane-LSB design should have high turn-down Stable regime Blow-off

31 Emission target area for new burners
Tested Medium (7.68 cm ID) Vane-LSB in Boiler Simulator at Arthur D. Little Medium Vane-LSB 210 < Q < 280 kW 0.58 < f < 0.95 100 101 102 103 104 0.0 5.0 10.0 15.0 20.0 25.0 NOx ppm (3% O2) CO ppm (3% O2) 7.5 cm vane-LSB at 280 kW f = 0.95 f = 0.58 Emission target area for new burners

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

33 Emissions of vane-LSB match Best Available Control Technology
Reached 1 MW thermal input and found lower NOx emissions with CO < 25 ppm and UHC below detectable limit 0.0 10.0 20.0 30.0 40.0 0.60 0.70 0.80 0.90 1.00 1.10 1.20 Equivalence Ratio, f NOx ppm (3% O2) 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
Simple Low pressure drop design for ultra-lean premixed flames that is scalable to different capacities Accepts different fuel types and fuel blends High turndown (at least 60:1) Flame does not hum Flash back conditions can be predetermined Ignites easily from either upstream or downstream Burner does heat up during operation Flame is not sensitive to enclosure or constriction Further NOx reduction with FGR

35 Laboratory Demonstration of LSB with External FGR
1 10 100 1000 5 15 NOx (3% O2) CO (3% O2) f = 0.8 f = 0.825 f = 0.85 f = 0.835 No FGR With FGR 2” LSB with vane-swirler fitted to a Telstar heat exchanger Flue gas drawn at the chimney Tested at 6 to 16kW with FGR up to 30%

36 Discovered Advanced 2 ppm NOx LSB Concept

37 Barriers and Constraints to Reaching < 2 ppm NOx
Burner stability near lean limits High CO and HC emissions Flame out and light off Safety concerns Excessive external FGR compromises efficiency Require precise control Lack of fuel flexibility and modulation capability

38 Combustion Scheme Based on Partial Reformed Gas
Exploit combustion features of hydrogen enriched natural gas flames Presence of OH radical suppresses CO the ultra-lean combustion conditions that deliver < 5 ppm NOx H2 lowers the lean flammability limit of natural/air combustion system thereby increasing the stability margin Needs advanced lean premixed burner technology to capture these benefits

39 CnHM + nH2O  nCO + (n + m/2) H2 H = 226 kj/mole
Steam Reforming CnHM + nH2O  nCO + (n + m/2) H2 H = 226 kj/mole Proven Commercial Technology Vendors for large and small reformers Thermal recuperators demonstrated for gas turbines Typical Industrial applications Temperature = 14000F (800oC) Ni-based catalyst active at 300oC Added water to maximize H2 concentration Need research and development on partial reforming

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

41 Burning of Partially Reformed Gas Lowers NOx and CO
Widens NOx-CO valley NOx < 2 ppm, CO < 10 ppm at 0.75 < f < 0.8 with 23 % reformed gas Needs to optimize f with percentage of partially reformed gas 1000 Reformed Gas 0% 10% 20% 100 CO (3% O2) 10 1 2 4 6 8 10 12 NOx (3% O2)

42 Overcoming Barriers Burner stability near lean limits
H2 in partially reformed gas improves lean stability limit High CO and HC emissions High OH radical pool leading to faster CO burnout Flame out and light off LSB with partially reformed gas is stable beyond current burner limits Safety concerns Burning of partially reformed gas expands the boundaries of operation, improves margin of safety Excessive external FGR affects efficiency Operate with lower excess air, while preserving low emission Tight control LSB is resilient to rapid changes in mixture and flow conditions Use of partially reformed gas further alleviates control needs Rigid/complex design No change in LSB design seems necessary

43 CIEE/DOE-OIT Cost-Shared Program Launched in September 2000
Objective: 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 NOx (3% O2). Participants: CIEE Component: LBNL, CMC Engineering DOE-OIT Component: LBNL, A. D. Little Current Funding Level: CIEE 300K, DOE-OIT 500K (FY01)

44 Overall Strategy Build upon CIEE Burner Research Effort
Two synergistic cost-shared developmental programs CIEE Component Develop scaling methods for large industrial LSBs Bench and pilot scale development of integrated partial reformer and LSB technologies DOE-OIT Component Conceptual design and evaluation of LSB with internal FGR and scale up to large industrial size Planned 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
LSB scaling and demonstration for large industrial systems Bench and pilot-scale development and demonstration of LSB with FGR and partial reformer Tasks: Scale-up and testing of LSB with FGR at UCICL (LBNL) Computational modeling of reformer kinetics (LBNL, CMC) Engineering analysis of reformer design, heat transfer and operation and bench-scale simulation testing with LSB (CMC, LBNL) Commercialization of basic LSB for industrial applications

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

48 CIEE Component - Oct 01 to Sep 02
Demonstration of partial reformer concept for industrial systems at pilot scale Tasks: Select demonstration site and defining demonstration target (LBNL/OEM) Bench scale partial reformer fabrication and assembly (CMC) Economic and market assessment of ultra-low NOx systems (CMC/LBNL) Secure commercial manufacturing agreement and licensing for large industrial 5 ppm NOx natural gas fired LSBs (LBNL)

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

50 Progress Report to 1-01

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

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

53 Scale-up and testing of LSB with External FGR at UCICL
Planned testing in UCICL boiler simulator Facility commissioned in Oct. 2000 Available for LSB testing in first quarter of 2001 Test plan for 3” vane-LSB push firing rate to 5 MMBtu/hr explore emissions and efficiency with FGR at different fs optional velocity measurements Test plan for larger vane-LSB UCICL Boiler simulator limited to < 5 MMBtu/hr 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
Conceptual system design for industrial process heat 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 Combustion air Fan Natural gas Flue gas

55 DOE-OIT Supported Tasks ON Performance Criteria of LSB with Partially Reformed Gas
Optimization of H2/CO concentration and equivalence ratio to meet design goals (i.e. < 5 ppm NOx and < 10 ppm CO, no UHC) Effects of steam addition to hardware Combustion stability of flame with H2 enrichment and steam injection Optimization 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
Integrated heat transfer to reformer Conversion performance at low catalyst temperature Effects of variation in gas composition Minimum steam requirements Durability testing of catalyst Reactor size and volume Catalyst resistance to sulfur Optimize design to prevent carbon formation

57 Activities on Partial Steam Reforming 9-00 to 6-01
Tasks: TECHNOLOGY ASSESSMENT PERFORMANCE ANALYSIS BENCH-SCALE TESTING ENGINEERING DESIGN TECHNICAL PRESENTATION

58 Technology Assessment for Partial Reformer
COMPLETED REFORMER TECHNOLOGY SURVEY AND ASSESSMENT: Literature search to identify NiO as the efficient reform catalysts that will be resistant to poisoning from sulfur in natural gas Energy requirement for reforming can be offset by burner and boiler efficiency improvements Reactor in reformer sizing tradeoffs with H2 output, cost, and hardware integration Commercial interest in technology approach for flame stability LOCATED HARDWARE SUPPLIERS AND ESTABLISHED COMMERCIAL SMALL-SCALE SUPPORT Corning, Sud-Chemie, and Fraunhofer Institut contacted and expressed interest to collaborate

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

60 Computational Modeling of Reformer Kinetics
Completed Perfectly Stirred Reactor (PSR) analysis using Chemkin chemical kinetic model Employed GRI-Mech 3.0 nitrogen chemistry Confirmed benefit of H2 addition to reduce CO at extremely lean conditions Effects of FGR on lowering NOx confirmed Will use Chemkin to optimize the amount of partial reformed gas needed to address tradeoff of performance and cost Compare with laboratory results to be obtained from DOE-OIT effort Results needed to verify scale up efforts for highly premixed lean industrial flames

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


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