Heat Rate Improvement Conference

Applying the Fundamentals for Best Heat Rate Performance of Pulverized Heat Rate Performance of Pulverized

Coal Fueled Boilers b i kby Dick Storm

Storm Technologies, Inc.

February 3-5, 2009Hyatt Regency Albuquerque, New Mexico

The Spread in Efficiency of the “Best” and the “Mediocre” Coal Plants

Source: NETL

There is potential for Improvement

Stealth Heat Rate Loss #1 – Air In-leakage

X gWall Fired Burner Evolution - High Intensity to Current

Low NOX Burner Design

Forgiving70’s High Intensity Burner

20’ FlamesIntensity Burner

SensitiveFirst Generation Low NOXBurner

Unforgiving2nd & 3rd Generation Low NOX

Burners w/ OFA / Staged C b ti

Challenging !

Combustion 60’ Flames

Modern Low NOX Burners should have Precise Fuel and Air Inputs

• Wall fired low NOX burners use the same fundamental principles.p p

• Furnace residence time for controlled, delayed mixing of air and fuel is finite.

• The 3 “T’s” can no longer be applied;The 3 T s can no longer be applied;• The 13 Essentials must be applied!

1960-70’s High I iIntensity Burner

This graph illustrates typical time requirements for combustion of coal. These times will vary with different coals & firing conditions

b t th b ti f b l i th t ti

Heating and Minor

but the combustion of carbon always requires the most time.

Heating and MinorDevolatilization

Ignition

MajorDevolatization

0 000 0 200 0 400 0 600 0 800 1 000

Burning ofCarbon

0.000 0.200 0.400 0.600 0.800 1.000Time (Seconds)

Note: This is why small particle sizing is important.

RESIDENCE TIME

Modern Pulverized Coal Plants Have at Least Three Major Airflow Paths

Combustion Air Required for Various Fuels

Combustion Air Required for Various Fuels

Fuel Source Moisture Vol. Matter Fixed Carbon Ash HHV

All at 110% of Theoretical Air Lbs/mmBtu's

Pennsylvania Bituminous 3.3 20.5 70 6.2 14000 842yOhio Bituminous 4.9 36.6 51.2 7.3 12500 838

W. Virginia Bituminous 2.4 33 60 4.6 14000 845Kentucky Bituminous 7.5 37.7 45.3 9.5 12000 851

Wyoming Sub- Bituminous 23.2 33.3 39.7 3.8 9400 833y g

N. Dakota Lignite 34.8 28.2 30.8 6.2 7000 825Texas Lignite 33.7 29.3 29.7 7.3 7000 827

Average 837

Highest 851 Lbs/mmBtu

Lowest 825 Lbs/mmBtuWithin ± 2 % of the mean

Comparisons of Eastern & Western Fuels

Total Air For Lb. Air/Lb. Fuel Required for % Primary % of

Airflow Requirements At Optimum Primary Airflow

Combustion lbs./mmBtu's

Required for Complete

Combustion

% Primary Air Secondary And

OFA

Typical PRB 832 7.1 25% 75%Typical PRB 832 7.1 25% 75%Typical Bituminous 838 11 16% 84%

Air FuelFuel

Burner Stoichiometry

From the Example:Burner Stoichiometry: no Leakage:

0.92 Averages9Burner Stoichiometry: 7% Leakage:

0.855

i h b l fWith Burner Imbalances of:5% Primary Air5% Secondary Air10% Fuel Flow

These imbalances are themaximum allowable. Most unitshave imbalances much higher!10% Fuel Flow

Maximum and minimum burner stoichiometry b d b b i b l

have imbalances much higher!

based on above burner imbalances

Lowest Possible Average Highest PossibleStoichiometry 0.738 0.855 0.997Stoichiometry

Excess Air0.738 0.855 0.997

-26.2% -14.5% -0.3%

g gTypical opportunities identified for Improvement as a

result of diagnostic testing

• Air in-leakage prior to the air heater• Air in-leakage prior to the air heater• Air heater leakage• A.H. Exit Gas Temperature (corrected for leakage)

higher than design• High Primary Airflow• High FEGT and Major Stratificaitons• High FEGT and Major Stratificaitons• Auxiliary Power is excessive due to high APH

differential and air in-leakageb l d f i hi h l i fl• Unbalanced furnace requires higher total airflow

• Burner tuning issues• NOX and/or LOI ImprovementsNOX and/or LOI Improvements

Air In-Leakage and X-Ratio

95% of Combustion Airflow (650°F)

20% of Combustion Airflow to Burner Compartment

Boiler Exit Flue Gas (720°F)

to Burner Compartment

20% of Combustion Airflow to Burner Compartment

20% of Combustion Airflow to Burner Compartment

20% of Combustion Airflow  Air Heatersto Burner Compartment

15% of Combustion Airflow to Pulverizers

Air Heater Leakage Paths

Airflow to Pulverizers5% of Tempering 

Airflow to Pulverizers

APH Flue Gas Exit & APH Leakage Air (267°F)(Corrected to No‐Leakage Temp of 305°F)

110% of Total Combustion Airflow required (80°F) Force Draft Fans

Temp. of 305°F)10% Air Heater Leakage5% Tempering Airflow15% Pulverizer Hot Airflow80% Secondary Airflow to Burners110% of Total Combustion Airflow Requiredq

Notes:1.) The Boiler (APH) Exit Gas Temperature appears to be 38°F lower than

it actually is for calculating Boiler Efficiency.2.) Based on a typical Eastern Bituminous Fuel with a Primary Air/Fuel

ratio of 1.8/1.0 and 10% leakage of the Airheater

gImportance of Total Airflow Measurement Control and

Minimization of Air In-Leakage

While it’s not uncommonto find 50-100 Btu’s/kWhr

h i h i ’at the air heater, it’s notuntypical to identify highair in-leakage within thegboiler setting (bottom ashhopper to air heater)which can often yield anwhich can often yield anadditional 100-200Btu’s/kWhr in heat ratei timprovement

Examples of “Stealth” Losses by Air In-Leakage

gIdeal Leakage (in a perfect world) is about 7% total

leakage from furnace to stack

Air Heater Leakage Red ction

Gas In Air Out

Air Heater Leakage Reduction

Out

Air heater leakage should not exceed

10%Gas Out Air In

High Flue Gas Temperature Peaks

High flue gas temperature “peaks” and the corresponding peaks of individualtube temperatures. The point is, poor distribution of hot gas lanes, oftencorrespond with overheated tube circuits.

Unacceptable combustion with products of combustion

Secondary Superheater

Reheat

Primary Superheater

NOTE: Flame carryover into the superheater contributes to

slagging, overheated metal temperatures and sometimes high

carbon content in the flyash

with products of combustion reaching the superheater

Reheat Superheater

Economizer

Air Heater

/To Precip./ Bag House

Air Inlet

gApplying the fundamentals comprehensively

is effective and does get RESULTS!

Economizer Exit Gas Temp and Oxygen Traverse

Furnace Exit HVT T and Oxygen Traverse

Furnace Exit HVT T

Furnace Exit HVT T

Economizer Exit Gas Temp and Oxygen TraverseTraverse

Vertical Fuel Line Test Connections for:

and Oxygen TraverseTraverse

Vertical Fuel Line Test Connections for:

Traverse

Vertical Fuel Line Test Connections for:

Fuel FinenessFuel DistributionClean Air VelocityDirty Air Velocity

Air Heater Exit Flue Gas for Temp, Oxygen, and

Flyash Sampling

Fuel FinenessFuel DistributionClean Air VelocityDirty Air Velocity

Air Heater Exit Flue Gas for Temp, Oxygen, and

Flyash Sampling

Fuel FinenessFuel DistributionClean Air VelocityDirty Air Velocity

Air Heater Exit Flue Gas for Temp, Oxygen, and

Flyash Sampling

Secondary Air Velocity Traverse Locations: Each of 4 Corners

Primary Airflow Measurement

Secondary Air Velocity Traverse Locations: Each of 4 Corners

Primary Airflow Measurement

Secondary Air Velocity Traverse Locations: Each of 4 Corners

Primary Airflow Measurement

p pStealth Heat Rate Penalties that are Controllable by

boiler combustion and performance optimization

The Total System Approach to Performance OptimizationTramp Air in leakageTramp air in-leakage

High furnace exit gas temperatures contribute to high de-superheating spray water flows that are significant steam turbine cycle heat-rate penalties.

High furnace exit gas temperatures contribute to high desuperheating spray water flows that are significant steam turbine cycle heat rate penalties.

High furnace exit gas temperatures contribute to overheated metals, slagging, excessive sootblower operation, production of popcorn ash, fouling of SCR’s and APH’s

Tramp air in-leakage causes heat losses and auxiliary power waste.

Accurate secondary airflow measurement and control, contributes to optimum

b i i i l NO d

High furnace exit gas temperatures contribute to overheated metals, slagging, excessive sootblower operation, production of popcorn ash, fouling of SCR’s and APH’s.

Accurate secondary airflow measurement and control. Contribute to optimum combustion, minimal NOx and reduced

Tramp air in-leakage causes heat losses and auxiliary power waste

Yard crusher use

combustion, minimal NOx and reduced de- superheating spray water.

Bottom ash carbon content and bottom ash hopper air in-leakage

,de-superheating spray water.

Bottom ash carbon content and bottom ash hopper air in-leakage

Yard crusher use contribute to

Air in leakage after the Aphcontributes to wasted ID fan power and capacity.

contributes to protecting pulverizers and coal feeders from tramp metal and large rocks. Also increases fineness capability of the pulverizers, for a given size coal pulverizers.

Coal pulverizer spillage Fl h C b l

protecting pulverizers and coal feeder from tramp metal and large rocks. Also increases fineness capabilty of the pulverizers, for a given size of coal pulverizer.

Coal pulverizer spillage from

Air in-leakage after the APH contributes to wasted ID fan power and capacitypower and capacity.p p g

from pulverizer throats that are too large

Accurate primary airflow measurement and control is required for optimum furnace combustion and reduced upper furnace exit gas temperatures. Also, NOx reduction.

Flyash Carbon losses

High primary airflows contribute to unnecessarily high dry gas losses. Also poor fuel distribution

and poor coal fineness.

p p gpulverizer throats that are too large

High primary airflow contribute to unnecessarily high dry gas losses. Also poor fuel distribution and poor fineness

Accurate primary airflow measurement and control is required for optimum furnace combustion and reduced upper furnace exit gas temperatures. Also, NOx reduction.

Flyash Carbon losses power and capacity

Case Study of Back to the Basics

Applying the fundamentals comprehensively is effective and does get RESULTS!

Furnace Exit Economizer Furnace Exit HVT Traverse

Economizer Exit gas Temp and Oxygen TraverseVertical Fuel

Line Test Air Heater Exit Flue Gas for Temp, Oxygen, and Flyash

Line Test Connections for:Fuel Fineness Fuel Distribution Cl Ai V l i and Flyash

SamplingClean Air Velocity Dirty Air Velocity

Secondary Air Velocity Traverse Locations: Each of 4 Corners

Primary Airflow Measurement

p p yNote Years 3 and 8: These are where boiler and

combustion performance was a priority

Getting Started: First Prepare to Test

Item  Description  Outage Provisions 

1.0  Pulverizer & Fuel Line Performance  

1.1   Clean Airflow Balance  

fl lTest Ports  Must be Installed  

1.2   Dirty Airflow Balance 

1.3   Fuel Flow Balance 

1.4   Air‐Fuel Ratios 

1.5   Pulverized Coal Fineness 

2 0 P i Ai fl C lib i2.0   Primary Airflow Calibration 

3.0  Secondary Airflow Distribution & Control  

Accessibility & Testing Ports  are Required  

4.0  Excess O2 Probe Measurement Accuracy

Multi‐point test probes are Preferred Accuracy 

p p

5.0  Furnace Exit Gas Temperature & Flue Gas Measurement   

Water & Air Supply Hoses & Fittings will need to beprepared; Safe Test Platforms; Test Ports (test ports ‐ bent tube openings with observation / test door assemblies)  

6.0  

Boiler Exit to Stack Flue Gas Measurements; Air Heater Performance; Boiler Efficiency & Total System Air In‐leakage Measurement  

Accessibility & Testing Ports  are Required  

7.0  Insitu Flyash Sampling & Analyses for Sizing & unburned carbon  

Accessibility & Testing Ports  are required; Multi‐Point Emission Sampling Systems by STORM TECHNOLOGIES are suggested for ease of testing/daily measurements  

Important Test Locations

PORT 6 PORT 1 PORT 2 PORT 3 PORT 5PORT 4 PORT 6

NORTH DUCT SOUTH DUCT

PORT 1 PORT 2 PORT 3 PORT 4 PORT 5

PORT 1 PORT 2 PORT 3 PORT 4

HVT

PORT 3PORT 1 PORT 2 PORT 4

Over fire Air Compartments

Economizer Outlet

Over fire Air Compartments

Main Secondary Air Ducts

PORT 2

PORT 3

PORT 4

PORT 5

PORT 6

PORT 6 PORT 6

PORT 5 PORT 5

NORTH DUCT

PORT 8

PORT 7

PORT 9

PORT 8

PORT 7

PORT 9

PORT 10 PORT 10

SOUTH DUCT

PORT 7

PORT 8

Wind box Compartments

PORT 1

PORT 1

PORT 2

PORT 1

PORT 2

PORT 4

PORT 3 PORT 3

PORT 4

PORT 1

PORT 2

PORT 3

PORT 4

PORT 5

PORT 6

PORT 1 PORT 2 PORT 3 PORT 4 PORT 5 PORT 6 PORT 7 PORT 8

Coal PipingPrimary Air

Venturis

PORT 1

PORT 2

PORT 3

Typical Opportunities for Improved Heat Rate

Controllable Variable Qualities

Air In‐Leakage 200 Btu/kWhAir In Leakage 200 Btu/kWhPrimary Airflow Optimization 50 Btu/kWhPulverizer Optimization and Improved Fuel Line B l 100 Bt /kWhBalance 100 Btu/kWhReducing Air Heater Leakage 80 Btu/kWhReduced Coal "Pyrites" Rejects 40 Btu/kWhReduced Carbon in Ash 50 Btu/kWhReduction of de‐superheating spray water flows 50 Btu/kWh

Total: 570 Btu/kWhTotal: 570 Btu/kWh

The key to successful application of the fundamentals:

T-E-A-M-W-O-R-K of all

yApply the fundamentals for a full year of performance

excellence in 2009 and beyond!

• “Best” Heat RateHi h C it F t • High Capacity Factor

• High Reliability• Lowest NOX Emissions• Burn Lowest Cost Fuels• Minimize Supporting

Flame Fuel (Oil and Gas)

Being the “Best in Class” means that all work groups MUST have thesame plan of action and agenda, due to the Inter-relationships ofcombustion factors on the total plant system. “Best” turbine

Thank You! Now please go performance requires “best” boiler performance!

p gApply the Fundamentals!