Ultra-Low Emission Burner forHigh Efficiency Boilers and

Furnaces

Presentation to CIEE

January 3, 2000

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

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

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

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

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

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

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

Projects

Advanced Combustion System

Flame Coupling With Its Environment

NASA Microgravity Combustion

Burner & Combustor Development

Cal. Inst. of Energy EfficiencyDOE-OPT Adv. Turbine SystemsDOE-OIT Combustion LBNL LDRD

Fundamental Flame Turbulence Interaction Processes

DOE SC-Basic Energy SciencesLBNL LDRD

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

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

Principle of Flame Stabilization by Low-Swirl

Fuel/Airmixture

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

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

DOE ER-LTR SupportedLSB 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 HeaterComputer monitoring of efficiency and concentrations of NO, CO and O2

Vane-Swirler Is The Critical Component Of LSB Technology

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

Vane-swirler

Rh

R

Screen

Premixture

Exit tube

Top view of patented vane-swirler

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)

Demonstrate high firing rates

Determine swirl requirement and emissions

10 cm LSB

5 cm LSB

UCICL Furnace Simulator for Large (10.16 cm ID) Jet-LSB

screens

honeycomb

air

swirl air

80 cm

fuel

Lpremixing zone 10.16 cm

MIDDLESTACK

REARSTACKBURNER

CHILLWATERPIPES

SAMPLING PORTS

STACKDAMPER

To emissionanalyzers

REACTANTAIR IN

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

reactant air

5.28 cm

fuelfuel

screens40 cm

premixing

zone

swirl air

L

Comparison of Stability Regimes of Large and Small Jet-LSBs

0 4 8 12 16 20 24 280.00

0.02

0.04

0.06

0.08

0.10

0.12

U, reference velocity (m/s)

Ge

om

etr

ic S

wirl

Nu

mb

er

, Sg

106 kW

18 kW

146 kW

585 kW

StableUnstable

5 cm 10 cm

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.

Firing rate (kW) for the 5 cm LSB

NO

x p

pm

(3%

O2)

100 200 300 400 500 600

5

10

15

20

2525 50 75 100 125 150

5 cm Burner10 cm Burner

Firing rate (kW) for 10 cm LSB

NOx Independent of Burner Size and Input Power

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

• 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 LSB25 50 75 100 125 150

CO

em

issi

ons

in p

pm (

corr

. to

3% O

2)

Firing rate (kW) for the 10 cm LSB

LO

G S

CA

LE

100 200 300 400 500 6001

10

100

1000

10000

5 cm, Ac / Ab = 155 cm, Ac / Ab = 14210 cm, Ac / Ab = 733

Chamber Size Affects CO

• UHC also depends on chamber/burner interaction.• UHC drops below detectable limit at high firing

100 200 300 400 500 6000

25

50

75

100

125

Firing rate (kW) for the 10 cm LSB

UH

C e

mis

sion

s in

ppm

(co

rr. t

o 3%

O2)

2800 ppmat 17.5 kW

5 cm, Ac / Ab = 14210 cm, Ac / Ab = 733

25 50 75 100 125 150Firing rate (kW) for the 5 cm LSB

UHC Limits Minimum Firing Rate

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

Summary of Results6-99 to 9-00

Pursue More-science-less-art approach to burner design and scaling

Parametric Study of Vane LSB Burner radius, R

Swirler recess distance, L

Equivalence ratio, 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

2/)//( RmmU fuelfuelairair

2)m

m(

A

RR

totalgS

lhrWkmQ fuelfuel /1035.0*)/(

R = 2.63 and 3.8 cm, Rh/R = 0.776

Eight thin guide-vanes with = 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

Specifications of Two Vane-LSB

Prototypes

Defining a Swirl Number

S R rdr rdrR

R

R

h

= UWrdr U + U0

2 2

0

Rh

S

R R

R R U Uv

h

h c a

2

3

1

1 1

3

2 2tan

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

Defining A Swirl Number for Vane-LSB Parameters:

Vane angle Ratio of burner to center body radii Rh/R = R

centerbody/annular of mass flux ratio

For the 7.68 cm ID LSi = 37o, R = 0.8

m can be estimated from effective area ratio

mmm ac /

22222

3

])1/1([1

1tan3

2

RRmR

RS

Screen blockage m S74% 0.833 0.49271% 0.901 0.4769% 1 0.43

Velocity Measurement of Vane LSB Flowfield

Comparison 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 10 20 30 40 50

Axial Distance (mm)

U (

m/s

)

Jet-LSB

Vane-LSB

-2

0

2

4

0 10 20 30 40 50

Axial Distance (mm)

U (

m/s

)

Jet LSBVane LSB

U= 2.5 m/s U= 10 m/s

Determine LSB Performance With Different Screens and Swirl Numbers

with 65% screen, at lean blow off is not a strong

function of U

Vane-LSB design should have high turn-down

0.5

0.6

0.7

0.8

0.9

1.0

0 2 4 6 8 10 12 14

Reference velocity U (m/s)

a

t le

an

blo

w-o

ff 60%65%

70%75%

Stable regime

Blow-off

Tested Medium (7.68 cm ID) Vane-LSB in Boiler Simulator at Arthur D. Little

Medium Vane-LSB

210 < Q < 280 kW

0.58 < < 0.95

100

101

102

103

104

0.0 5.0 10.0 15.0 20.0 25.0

NOx ppm (3% O2)

CO

pp

m (

3%

O2)

7.5 cm vane-LSB at 280 kW

= 0.95

= 0.58

Emission target area for new burners

LSB Demonstrated at 1 MW Extensive 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"

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 1.20Equivalence Ratio,

NO

x p

pm

(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

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

Laboratory Demonstration of LSB with External 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% 1

10

100

1000

0 5 10 15NOx (3% O2)

CO

(3%

O2)

= 0.8

= 0.825

= 0.85

= 0.8

= 0.835No FGR

With FGR

DiscoveredAdvanced 2 ppm NOx LSB Concept

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

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

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

LBNL Demonstration

Firing synthetic partially reformed gas with FGR at 60

kBtu/hr

Varied methane/air equivalence from 0.78 < < 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

Burning of Partially Reformed Gas Lowers NOx and CO

Widens NOx-CO

valley

NOx < 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

0 2 4 6 8 10 12

NOx (3% O2)

CO

(3%

O2)

0%

10%

20%

Reformed Gas

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

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)

Overall Strategy Build upon CIEE Burner Research Effort

Two synergistic cost-shared developmental programs CIEE Component

Develop scaling methods for large industrial LSBsBench 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?

Planned Schedule

10-00 to 9-01 10-01 to 9-02 10-02 to 9-03 10-03 to 9-04Burner research andengineering(continuation of LBNL CIEEmultiyear project)

Scale-up of vaneLSB to 10 MMBtu

Scale-up to> 10 MMBtu/hr

R&D on implementingpartially reformed gasscheme (LBNL, CMC)

Bench scaledemonstration(LBNL lead)

Demonstrationfor industrialsystems(CMClead)

Collaboratewith OEM forsystemoptimizationand control

Prototypedemonstrationfor smallindustrialtesting

R&D on scale up andcontrol of LSB with internalFGR(LBNL, ADL)

Concept Designand Evaluation(LBNL, ADL co-lead)

Design conceptscale up to 30MMBtu/hr (ADLlead)

Collaboratewith burnerOEM forproduct design

Prototypedemonstrationfor smallindustrialtesting

Commercialization Industrialburners < 5MMBtu/hr

Commercial demonstration ofLSB in large industrial systems

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

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)

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)

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)

Progress Report 10-00 to 1-01

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

Demonstrated Power Capacity of Low Swirl Stabilization Method

0.00

500.00

1000.00

1500.00

2000.00

2500.00

0.0 20.0 40.0 60.0 80.0 100.0

Bulk Velocity, U (m/s)

Po

we

r (k

W)

5 cm LSB, P = 1 atm

7.5 cm LSB, P = 1 atm

10 cm LSB, P = 1 atm

7.5 cm LSI, P = 5 atm

7.5 cm LSI, P = 10 atm

UCICL

Solar Turbines

Solo Energy

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 s 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

Engineering Analysis of Reformer Design, Heat transfer and Operation

PremixedBurner

Main Radiant furnace

Convective section of furnace

Stack

Nat. gas +flue gas +reformedgas

SteamReformer

Path of flue gas

Recirculated flue gas

Steam

Combustion airFan

Natural gas

Flue gas

Conceptual system design for industrial process heat

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

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

Activities on Partial Steam Reforming 9-00 to 6-01

Tasks: TECHNOLOGY ASSESSMENT PERFORMANCE ANALYSIS BENCH-SCALE TESTING ENGINEERING DESIGN TECHNICAL PRESENTATION

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

Progressing Towards Laboratory Demonstration

Developing an existing burner stations in 70-141 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

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

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