moulton - biomass co-firing_pittsburgh

8/4/2019 Moulton - Biomass Co-Firing_Pittsburgh

1/42

Pittsburgh Technical SeminarAugust 23, 2011

Biomass Technologies & PC Co-FiringPresenter: Brad Moulton, PE

Director, Environmental Systems


2/42

1

Biomass Solutions for Existing Steam Generators

FW Biomass Gasifier in PC Co-fireApplication

Co-firing Direct Combustion Blend biomass on coal pile or separate

injection with or without burner modifications

5 10% by heat input

FW very active in EPRI and TVAdemonstration projects in the US

Co-Firing Gasification Substitute fuel for coal, oil, or gas fired boilers

Substitute fuel for HRSG firing duct burner

Over 50% by heat input

FW has supplied 8 gasifiers commercially

100% Biomass Conversions

Convert existing oil, gas, or pc unit intobubbling bed

Retrofit fuel delivery and combustion systemsto fire 100% biomass in existing units

FW has performed over 25 conversions


3/42

2

HEATING

VALUE,MJ/kg

20

35

0 1 2 5

5

10

10

PEAT

BARK

WOOD BIOMASS

DEMOLITIONWOOD

CHIP-BOARD

POLYOLEFINPLASTICS

(PE, PP, PC...)COLORED

OR PRINTEDPLASTICS,CLEAN

COLORED

OR PRINTEDMIXED

PLASTICSREF

PLY-WOOD

PVC

RDF

MSW

PVCCONSUMER

REF II -IIIMIXED

PLASTICS

PAPER &WOOD

BROWN COAL,LIGNITE

PETROLEUM COKE

CHICKENLITTER

DEINKINGSLUDGE SEWAGE

SLUDGEBIO &FIBERSLUDGE

REFPELLETS

WOOD&PLASTICS

COWMANURE

REF ICOMMERCIAL &

INDUSTRIAL

BITUMINOUSCOAL

ANTRACITECOAL

HEATING

VALUE,MJ/kg

20

35

0 1 2 5

5

10

10

WOOD BIOMASS

DEMOLITIONWOOD

CHIP-BOARD

POLYOLEFINPLASTICS

(PE, PP, PC...)COLORED

OR PRINTEDPLASTICS,CLEAN

COLORED

OR PRINTEDMIXED

PLASTICSREF

-

PVC

RDFMSW

PVCCONSUMER

REF II -IIIMIXED

PLASTICS

PAPER &WOOD

PETROLEUM COKE

MULTIPLECHALLENGES

SOMECHALLENGES

STANDARDDESIGN

CHICKENLITTER

DEINKINGSLUDGE SEWAGE

SLUDGEFIBERSLUDGE

REFPELLETS

WOOD &PLASTICS

COWMANURE

REF ICOMMERCIAL &

INDUSTRIAL

Oil Shale

Estonian Mid-East/

N. African

Peat w/HighCa,

Peat w/HighCa, Cl, Br

BITUMINOUSCOAL

ANTRACITE

COAL

BIO &

BROWN COAL,LIGNITE

PEAT

BARK

WOODPLY

GrateCombustionFluidized Bed Combustion

PC FuelRange

CFB FuelRange

FW has a Wide Solid Fuel Experience


4/42

3

Biomass Fuel Properties Vary Widely- Expertise is needed to Burn Reliably

Bark Wood ChipsForest

ResidueSaw Dust

WoodPellets

DemoWood*

Switchgrass Corn Stover Wheat Straw Bagasse*

HigherHeatingValue

Btu/Lb 4,400 4,340 6,230 3,659 6,230 4,080 5,430 7,700 8,400 5,720 6,800 7,400 6,800 7,400 6,290 7,150 7,320

Density lb/ft3 18 16 20 16 20 14 20 32 40 18.0 5.5 7.0** 8 12** n/a n/a

Moisture % a.r. 50 27.5 50 28 46.9 34.9 51.6 4 8.6 30.0 4 10 4 13 7 13 10.4

Ash % a.r. 1.45 0.4 0.6 0.6 14.48 0.3 0.7 0.25 11 4.0 2.1 8.9 0.8 10.2 3.89 8.31 2.19

N % a.r. 0.10 0.06 0.08 0.26 0.308 0.02 0.3 0.01 1.23 1.0 0.31 0.77 0.51 4.16 0.39 0.46 0.14

S % a.r. 0.10 0 0.01 0.01 0.03 0.01 0.03 0.02 0.27 0 0.01 0.22 0.1 0.94 0.14 0.26 0.04

Cl % a.r. 0.01 0 0.005 0 0.005 0 0.01 0 0.09 0.01 0.01 0.15 0.05 0.25 0.13 1.79 0.03

K2O % a.r. 0.09 0.11 1.09 0.08 1.46 0.03 0.07 0.00 1.80 0.28 0.05 1.75 0.12 2.81 1.32 2.36 0.09

Na2O % a.r. 0.02 0.00 0.16 0.00 0.17 0.00 0.02 0.00 0.36 0.04 0.01 0.15 0.01 1.24 0.04 0.93 0.02

* Indicates representative values** Indicates unconsolidated density. In pellet form treat as 40 lb/ cu ft. Revised per D. Tillman 012710


5/42

BiomassProperties

Peat Saw DustRecycled

Wood

Timber

Pellets

Timber

ChipsGrass RDF Bagasse Straw

Moisture % 50 45-60 25 5-10 20-50 13 25 8 12

MJ/kg 9.3 6-10 14 17 7.5-13.9 17 13 16 14.7

Btu/lbm 4000 2580-4300 6020 7310 3225-5975 7310 5590 6875 6320

Bulk Density kg/m3 340 300-350 300-400 650 130-280 650 650 650 650

Bulk Density lb/ft3 21 19-22 19-25 41 8-17 40 40 40 40

MWh/m3 0.9 0.45-0.7 1.3 3 0.55 3 2.3 2.9 2.7

Ash % ka 5.1 0.4-0.5 5 0.9 0.4-5.3 3 12 6 7

S % ka 0.22


6/42


7/426

Impacts to Steam Generators by Bio Type


8/42

Biomass Annual Flows

Unit Size in Megawatts Electric Annual Biomass Flows In Tons

25 186,944

50 373,888

75 560,832

100 747,776

200 1,495,551

300 2,243,327

7

Note: Fuel moisture @ 40% with 85% annual capacity factor


9/42

PC Biomass Co-Firing


10/42

Introduction

Co-firing of biomass with coal gaining increased interest in utilityindustry

Cost-effective option for utilities to address increasing renewable portfoliostandards

Generally considered a renewable fuel

Carbon neutral

Biomass co-firing in US began in early 1990s as part of

government funded projects

Foster Wheeler participation included

Primary contractor to EPRI in development of biomass utilizationtechnologies

Participated in numerous tests and demonstrations

Recently evaluated conversion of numerous generating stations to co-firinginstallations


11/42

Foster Wheeler Past Experience

Plant Owner Firing Method FWNAC Role

Allen Fossil Plant TVA Cyclone Led test program

Kingston Fossil Plant TVA T-fired PC Supported tests

Colbert Fossil Plant TVA Wall-fired PC Led test program

Michigan City Generating Station NiSources (NIPSCO) Cyclone Led test program

Bailly Generating Station NiSources (NIPSCO) Cyclone Led demonstration program

Seward Generating Station GPU Genco Wall-fired PC Led demonstration program

Shawville Generating Station GPU GencoWall-fired PC

T-fired PCLed test program

Albright Generating StationAllegheny Energy Supply

Co., LLCT-fired PC Led demonstration program

Willow Island Generating Station Allegheny Energy SupplyCo., LLC

Cyclone Led demonstration program

Blount St. Station Madison Gas & Electric Wall-fired PC Supported test program

Plant Gadsden Southern Co. T-fired PC Supported test program

Ottumwa Generation Station Alliant Energy T-fired PCSupported test program with

preliminary engineering


12/42


13/42


14/42

Reduces Greenhouse Gas Emissions

Reduces SO2 Emissions

Reduces Mercury Emissions Reduces NOx Emissions in Most Cases

13

Biomass Co-firing Environmental Benefits


15/42

Important Fuel Differences between Biomassand Coals

Important Differences between Biomass and Coals

Higher Moisture

Reduced Heat Content

Higher Volatility (FC/VM Ratio)

Increasing concentration of available and reactive alkali metalsand alkaline earth elements

Increasing concentration of halogens (e.g., Cl, Br)

Bulk density differences

Biomass

Fibrous, shred along fiber lines

Consequently, do not pulverize well using traditional techniques


16/42

Example of Biomass Properties

Proximate Analysis (weight %, asrecd)

Sawdust(spruce) Switchgrass Olive Residues

EasternBituminous

(Pitts#8)

Powder RiverBasin

(Rochelle/N. Ant.)

Moisture 34.93 15.00 6.00 3.50 27.30

Volatile Matter 55.03 65.18 73.10 38.60 32.10

Fixed Carbon 9.34 12.19 16.84 48.00 36.20

Ash 0.69 7.63 4.06 9.90 4.40

Ultimate Analysis (weight %, asrecd)

Carbon 32.06 39.68 49.33 71.20 51.45

Hydrogen 3.86 4.95 7.39 4.70 3.50

Nitrogen 0.26 0.65 2.00 1.20 0.65

Sulfur 0.01 0.16 0.05 2.60 0.21

Oxygen 28.14 31.74 30.91 6.80 12.49

Higher Heating Value (Btu/lb, asrecd) 5,431 6,601 8,990 12,730 8,800

Chlorine (%, as recd) 0.05 0.19 0.26 0.10 < 0.01

Chlorine Loading (lb Cl/106 Btu) 0.092 0.288 0.289 0.079 0.011

Sodium Loading (lb Na/109 Btu) 29 67 23 30 95

Potassium Loading (lb K/109 Btu) 125 1,341 1,564 155 15


17/42

Nitrogen and Volatile Evolution for DifferentBiomass Fuels

0 500 1000 1500 2000 2500 3000 3500

VolatileYield,

%

Temperature, F

Nitrogen (Sawdust)

Volatiles (Sawdust)

Nitrogen (Switchgrass)

Volatiles (Switchgrass)


18/42

Methods of Co-Firing

Can be divided into three categories

Direct Co-Firing

Indirect Co-Firing

Parallel Combustion

Indirect co-firing and parallel combustion are recognized more in Europe,

however direct Co-Firing still appears to be favored. Direct Co-Firing is

primarily the method of biomass utilization within the U.S.

Direct Co-Firing can be further subdivided

Co-mingled with coal upstream of the feeders typically in the coal yard

Biomass is handled and processed separately within the confines of the existing firingsystem (e.g., co-axial with coal nozzles)


19/42

Co-Mingling of Biomass

Co-Mingling

Pushed around on the pile

Generally successful with less than 5% biomass (by weight)

Higher percentages through coal milling system has demonstrated

significant impacts on pulverizer performance

Lower capacity due higher moisture content

Mill plugging / bed build-up due to biomass particle high aspect ratio

Recent experience has shown little impact with up to 10% biomass (by

weight) At 15% biomass (by weight) low mill temperatures and high mill bowl

pressures caused a 5% load derate


20/42

Separate Injection of Biomass

Separate Handling & Injection

Higher percentage of biomass

Allows careful management of low bulk density fuels that may not

blend well with coals Mitigates pluggage of pulverizers caused by high aspect ratio

biomass particles

Higher capital costs


21/42

Co-firing Biomass Fuels in Coal Boilers

Increased volatility of biofuels is among the most criticalconsideration

Biofuel particles volatize earlier and independently of the fossilfuel particles

Causes some key changes in fuel particle-particle interactions;reducing the ignition temperature of the fuel mass

Most co-firing applications on PC combustion systems useseparate injection of fuel and biomass

Blending of biomass and/or other fuels in the coal yard can be utilized at

minimal biomass percentages At >10% biomass (mass basis), separate is most applicable and at times,

necessary


22/42

PC Firing Injection System is a Key

For tangentially-fired boilers, injectors are welldeveloped Injector placement at center of fireball works well for flame

stabilization, creating internal reducing zone

Transport velocities and transport air ratios are important

For wall-fired boilers, common system utilized Injection of biomass (typically and mostly easily managed is

sawdust) in the center of coal flame; modification of existing

burners Burner design concepts exist for multi-fuel co-firing, maximizing

NOx reduction


23/42


24/42

Co-Firing in Tangential Boilers (Contd)

Separated OverfireAir Windbox

MainWindbox

Warm-Up Compartment

Ideal locations are auxiliary air

nozzles between the middlecoal elevations


25/42

Co-Firing in Tangential Boilers (Contd)

Large, round openingin center

Biomass transport and

discharge velocities

typically 80 90 ft/s

Peripheral air

controlled by windbox

dampers; however

should be designed for

velocities between

80 120 ft/s


26/42

Co-Firing in Wall-Fired Boilers

Methods of Biomass Introduction

Mixed with coal upstream (co-

mingled)

Co-axial with the coal nozzles

Injection through biomass

nozzles replacing coal nozzles

Injection through separate,

dedicated furnace waterwallopenings


27/42

Co-Firing in Wall-Fired Boilers (contd)

Most experience to date has beenwith coaxial injection

Air requirements for biomass are

very different as compared to coal

Wholesale conversion of entireburners to fire biomass presents

the following challenges:

Controlling air to each burner

Possible windbox modifications


28/42

Typical Wall-Fired Burner Configuration forBiomass Co-firing


29/42

Wall-Fired Biomass Injectors

Biomass Injection Diffuser for Center FiredApplication

Rapidly disperse biomass in center of flame

Flame within Flame


30/42


31/42

Biomass Effects for Burners

Biomass can enhance burner stability with the early release ofvolatiles particularly when co-firing with low volatile coals

Low nitrogen and high volatile matter content of biomass cansignificantly enhance NOx reduction

Volatile matter is a key factor in creating low NOxcombustion conditions in flames

When tri-firing with low volatile fuels such as petcoke, biomasscan potentially offset negative impacts of these opportunity

fuels


32/42

Example of Low NOx Burner Flame TemperaturesWithout and With Co-axial Biomass Injection

Coal Only CaseTwo distinct area of high reaction rates:

a) The zone near the burner nozzlewhere volatiles are released surroundedby

b) A larger and longer zone where charoxidation occurs

Biomass Co-firing Case1) Two strong zones of volatile releasefrom biomass jet on burner axis

2) Flame is longer and has lower releaserates of coal volatiles and charoxidation

Although there is appreciable quantityof unreacted biomass volatile, thesevolatiles will readily react in the burnerinteraction region and above burnerzone

Co-combustion demonstrations haveshown modest and often favorableimpact of biomass on unburned carbon


33/42

Summary of NOx Reduction from Cofiring

NOx Reduction From Cofiring: Compilation of All Tests

0

5

10

15

20

25

30

0 5 10 15 20 25

Cofiring Percentage, Mass Basis

NOxReductionfromB

aseline,

Percentage

Line Indicates 1% reduction in NOx for every 1%

reduction in fuel nitrogen


34/42

Biomass and Fuels Management Considerations

Biomass can be used to increase total fuel volatility

High volatile fuel (typically >50%)

Low ash fuel (typically


35/42

34

Recognize that biomass transport lines are subject topluggage

High aspect ratios

Low air/fuel ratios [1.7 2.0 lb air/lb fuel]

Must be incorporated into design

Frequent clean-out provisions

Provisions for rapid identification where pluggage occurs



36/42

35


Keep transport velocities above the flame speed ofbiomass

Flame speed of biomass is > 5000 ft/min (83ft/sec)

Design of systems needs to consider thisparameter

Transport velocities of ~ 110 120 ft/sec have

proven to be useful


37/42

36


Particle sizing is important

Cyclones

- x 0 proves to be ideal

-Sizing up to x 0 or x 0 also works-Larger particles are typically assumed to work;particles will actually skip across the slag pooland fly through the boiler plugging up air heaters

PC firing-1/8 x 0 is ideal

- x 0 is acceptable


38/42

Example of Aspect Ratio


39/42

38


When biomass is moving, keep it moving

Avoid allowing biomass material to settle

e.g. filling biomass bunker at night while cofiring is

not used Settled material can become very difficult to move,

requiring excessive manpower


40/42

Co-firing Capacity Implications

Capacity Implications:

Cyclone boilers capacity limitations not experienced at orbelow 15% co-firing key issue is feeder speeds

PC boilers capacity derates can come quickly with

blended fuels- limitations result from pulverizer performance if the plant ispulverizer limited

- if spare pulverizer capacity exists, then fuel fineness maybecome an issue

PC boilers - capacity is not limited with separate injection provided sufficient ID fan capacity exists

Co-firing (PC boilers) can be utilized to recover some lostcapacity when there are wet coal issues


41/42

Typical Capital Costs

Direct Combustion/woody fuel:

$200 - $250/kW or Typically $1.5 - 2.0 Million

Direct Combustion/herbaceous fuel:

>$300/kW or Typically $2.0 - 3.0 Million

Gasification:

$500 600/kW or Typically $10 - 15 million

Capital Costs do not Vary Significantly by Boiler Type

O&M Costs are Highly Variable

40

Biomass Co-firing System Costs


42/42

Conclusions

Recent experience has demonstrated that biomass co-firing can

be successfully utilized in coal-fired boilers as an effective

means of reducing greenhouse gases

Renewable energy portfolio standards and possible tax

incentives may increase the opportunity for biomass co-firing

with coal

Co-firing solutions are available for tangential & wall-fired

boilers

Differences in biomass characteristics with respect to the co-

fired coal must be considered

moulton - biomass co-firing_pittsburgh

Documents