www.electricpowerexpo.com May 15‐17, 2012 – Baltimore, MD

FLY ASH EROSIONFLY ASH EROSIONCONTROL & PREVENTIONCONTROL & PREVENTION

RECENT DEVELOPMENTSRECENT DEVELOPMENTS

JOHN DRENNEN, PEJOHN DRENNEN, PEDRENNEN ENGINEERING, INC.DRENNEN ENGINEERING, INC.

FLY ASH EROSION (FAE)FLY ASH EROSION (FAE)

LEADING CAUSE OF BTF

PREVENTABLE…IN MOST CASES

OLD TECHNOLOGY…& NEW TOOLS

FACTORS CONTRIBUTING FACTORS CONTRIBUTING TO INCREASED FAETO INCREASED FAE

GAPS, OPENINGSTURNS IN FLOW PATH

SOOTBLOWINGFUEL CHANGEHIGHER LOAD

PP CHANGESFUEL FIRING EQUIP

ASH PLUGGINGEROSION CONTROLS

LOWER FLOW RESISTANCECENTRIFUGAL SEPARATIONFLY ASH SURGES MORE ASHHIGHER FLOWPREFERENTIAL FLOWTIME-TEMP HISTORYDECREASE FLOW AREACAN MOVE PROBLEM

FAE EQUATIONFAE EQUATION

E = C x M x Vnx Cp

E – Erosion Rate C – Correlation Const. M – Mass Flux V – Gas Velocity n – exponent (2.5 - 3.5) Cp – Particle Size Adjustment

RELATIVE EROSIONRELATIVE EROSIONEE11/E/Eavgavg = (M= (M11/M/Maa) x (V) x (V11/V/Vaa))nn x (Cx (Cp1p1/C/Cpapa))

Relative Erosion Rates(E1/Eavg, n=2.4)

0.0

0.5

1.0

1.5

2.0

0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

Relative Velocity

Rel

ativ

e So

lide

Load

ing

(0.18) (0.47) (E1/Eavg=1.00)

(1.86)

(5.0)

LARGE BOILERLARGE BOILER>750 MW>750 MW

FAE AREAS:FAE AREAS:PERIMETERPERIMETER

ININ--BANK BANK

APPROACH:APPROACH:CAVTCAVTCOMPUTER MODELCOMPUTER MODEL

FAE

FLOW

FLOW

FLOW

FAE

MIDMID--SIZE BOILERSIZE BOILER200 200 -- 750 MW750 MW

FAE AREAS:FAE AREAS:REAR PASS NEARREAR PASS NEARREAR WALLREAR WALL

APPROACH:APPROACH:COMPUTER & PHYSICAL MODELCOMPUTER & PHYSICAL MODELFOLLOWFOLLOW--UP CAVTUP CAVT

SMALL BOILERSMALL BOILER< 200 MW< 200 MW

FAE AREA:FAE AREA:ECON NEARECON NEARREAR WALLREAR WALL

APPROACH:APPROACH:COMPUTER MODELCOMPUTER MODEL

STEAMDRUM

FLOW(FROM STOKER)

MUDDRUM

FAE

APPROACH TO FAE REDUCTIONAPPROACH TO FAE REDUCTION

IDENTIFY ROOT CAUSEGAS & ASH DISTRIBUTION, OTHER…

MEASURE / MODEL DISTRIBUTIONSCAVT, COMPUTER, PHYSICAL MODEL

REDISTRIBUTE FLOWSFLOW MODIFICATION BAFFLES

COLD AIR VELOCITY TESTCOLD AIR VELOCITY TEST

Measure Gas Flow DistributionFULL SCALE PHYSICAL MODEL

Testing in Unit w/ Fans RunningMultiple Teams Flow Visualization

COLD AIR VELOCITY TEST - Multiple Teams at Different Planes - One Person Measures, the Other Records Readings & Notes - Safety Person for Each Team Outside at Same Plane - Control Room Operator Sets and Monitors Flow and Other Equipment to Support Test.

Control Room

ni j k l mhgfedcba

COLD AIR VELOCITY TESTCOLD AIR VELOCITY TEST

FLOW VISUALIZATIONFLOW VISUALIZATION

FLOW VISUALIZATIONFLOW VISUALIZATION

CO

LD A

IR V

ELO

CIT

Y T

ES

TC

OLD

AIR

VE

LOC

ITY

TE

ST

n-Rear

mlkjihgfedcba-Front

Left2

34

56

Right

0.00

0.25

0.50

0.75

1.00

1.25

1.50

1.75

2.00

Nor

mal

ized

Vel

ocity

Front-to-Rear

Side-to-Side

Normalized Velocty vs. Position

Normalized Velocity vs. Position(Column Averages)

0.0

0.5

1.0

1.5

2.0

0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00

Relative Position (Left-to-Right)

Nor

mal

ized

Vel

ocity

Normalized Velocity vs. Position(Row Averages)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0.0 0.5 1.0 1.5 2.0

Normalized Velocities

Rel

ativ

e Po

sitio

n (F

ront

-to-

Rea

r)

Rear

Front

Left Right

COMPUTER MODELINGCOMPUTER MODELINGCOMPUTER MODELING2-D OR 3-D

DEPENDS ON SYMMETRY

AMBIENT TEMPERATURE (CAVT)OPERATING CONDITIONS

W/ HEAT EXTRACTION

GROSS FLOW DISTRIBUTION GAS AND PARTICULATE

ESTIMATE RELATIVE FAE RATEDETAILED AREA MODELS

Inlet

Outlet

Nominal 1 Ft Wide Slice

Model

Div Wall

2-1/2-D CFD Model Geometry

HTSH

FLOW

FLOW

FLOW

FAE

3-D MODEL

PA DUCT EXTRACTIONASSYMETRIC

INLET

OUTLETTO AH

ECON BANKS

Gas Velocity3-Baffles

TEMPERATURE

INLET – 2350°FOUTLET – 700°F

PARTICULATE

30 & 53 MICRON

PARTICULATE

74, 88, 105 MICRON

PARTICULATE

177, 210 MICRON

0.0

1.0

2.0

3.0

4.0

5.0

0.000.100.200.300.400.500.600.700.800.901.00

Distance, Rear-to-Front (Ft)

Rel

ativ

e M

ass

& S

ize

Rat

io

No Baffles 3 Baffles

Relative Mass Loading w/ Size CorrectionRear Pass at Operating Conditions

40% REDUCTION

FrontRear

Uniform ash / size distribution = 1.0

FLOW

FLOW

FLOW

FAE

MIDMID--SIZE BOILERSIZE BOILER200 200 -- 750 MW750 MW

FAE AREAS:FAE AREAS:REAR PASS NEARREAR PASS NEARREAR WALLREAR WALL

APPROACH:APPROACH:COMPUTER & PHYSICAL MODELCOMPUTER & PHYSICAL MODELFOLLOWFOLLOW--UP CAVTUP CAVT

Hanger Tubes

Inlet

ScreenTubes

Outlet

LTSH

Nominal 1 Ft Wide Slice

Model

Div Wall

2-1/2-D CFD Model Geometry

HTSH

400 MW

INLET

BASELINEPARTICULATE: 10, 100, 150 MICRON

OUTLET

0

2

4

6

8

10

12

14

16

18

20

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0 13.0

Distance, Front-to-Rear (Ft)

Rel

ativ

e E

rosi

on R

ate

Mass Wtd. Mass & Part.

Adjustment to Account for Larger Particle Shift

to Rear of Pass

Peak at Wall Gap 21x Ideal

BASELINE

RELATIVE FAE TOP LTSH BANK INLET

FLOW

FLOW

1

2

3

5

4

6

7

CFD Model GeometryMAIN DIAGONAL SCREEN & TUBE BEND BAFFLES

Div Wall

LADDER VANEBAFFLE

EMS BAFFLE10, 23, 100 Particle Tracks

0.0

2.0

4.0

6.0

8.0

10.0

0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00 11.00 12.00 13.00

Distance, Front-to-Rear (Ft)

Real

itive

Ero

sion

Rat

e

Mass Wtd. Mass & Part.

Relative Erosion at Upper Rear LTSH Inlet

NEW FAE Controls

No Major Particle Shift to Rear

Rear Sect.Below Avg.

Peak in Front SectDue to Jet off Vanes

SMALL BOILERSMALL BOILER< 200 MW< 200 MW

FAE AREA:FAE AREA:ECON NEARECON NEARREAR WALLREAR WALL

APPROACH:APPROACH:COMPUTER MODELCOMPUTER MODEL

STEAMDRUM

FLOW(FROM STOKER)

MUDDRUM

FAE

FLOW VISUALIZATIONFLOW VISUALIZATION

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

10.0

11.0

12.0

13.0

14.0

15.0

16.0

17.0

18.0

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Economizer Tube Row Number

Nor

mal

ized

Ero

sion

Rat

e

Trajectories for 10 Micron Ash Particles

Economizer Inlet Plane

0.0

1.0

2.0

3.0

4.0

5.0

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Economizer Tube Row Number

Nor

mal

ized

Ero

sion

Rat

e

Trajectories for10 Micron Ash Particles

Economizer Inlet Plane

OTHER ISSUESOTHER ISSUES

IN BANK FAE

TUBE ALIGNMENT

PLUGGING

TEMPERATURE

Particle Tracks Through Bank

Particle Sizes Shown () :44, 62, 88, 125, 177, 250, 420

HighestParticle Impact

Zone

Particles are deflected off of top rowand then again by 4th row intoRows 5-8, where the most seriousFAE occurs.

FAE LOCATIONS

Particles are deflected by top rowand 4th row tubes into Row’s 5 - 8, where most serious FAE occurs.

Particle Tracks at Top of Bank

Particle Sizes Shown () :44, 62, 88, 125, 177, 250, 420

Flow

Sidewall

Offset SH tube

FLOW TO SIDEWALL GAP&

TUBE ALIGNMENT

PLUGGING DUE TO SOOTBLOWINGPLUGGING DUE TO SOOTBLOWING

PLUGGING DUE TO CARRYOVERPLUGGING DUE TO CARRYOVER

ASH DEFLECTION SCREENSASH DEFLECTION SCREENS

OVERHEATINGOVERHEATING

SUMMARYSUMMARYSTEPS TO REDUCE FAE

IDENTIFY LOCATIONS – FAE – ROOT CAUSE

GET FLOW DISTRIBUTIONSGAS AND FLY ASH

CAVT, COMPUTER OR PHYSICAL MODEL

CORRELATE FAE TO FLOW DISTRIBUTIONS

SELECT BAFFLES TO REDISTRIBUTE FLOW

GET MODIFIED DISTRIBUTIONS W/ BAFFLES

CAUTIONARY ITEMSPLUGGING, TEMPERATURE

FLY ASH EROSIONFLY ASH EROSIONCONTROL & PREVENTIONCONTROL & PREVENTION

J. DRENNENDRENNEN ENG, INC

QUESTIONS AND ANSWERS