13aph enhancements

8/9/2019 13APH Enhancements

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Air Preheater Enhancements

LEAKAGE


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HowdenWhat is leakage ?


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HowdenEffects of leakage drift on plant

Increase in fan power on all types of

boilers

Increased potential for down streamcorrosion

Higher flue gas volumes increase

emissions

Limited FD,ID and or PA fan power can

force reductions in output


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Cold end fouling

Normal deposits

Acid enhanced

Hot end fouling

Popcorn fouling

Example of bad hotend popcorn

fouling in a CUprofile


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0

100

200

300

400

Flue Gas Flow Direction

Steel PlatesSteel Plates

(Hot End Layer)(Hot End Layer)EnamelledEnamelled PlatesPlates

(Intermediate Layer)(Intermediate Layer)EnamelledEnamelled PlatesPlates

(Cold End Layer)(Cold End Layer)

HH22SOSO44 condensation bandcondensation band

Critical RangeCritical RangeMean Heating PlateMean Heating Plate

TemperatureTemperature

NHNH44HSOHSO44 condensation bandcondensation bandAirAir

HeaterHeater


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What causes leakage drift ?

Adjustable sealing plates with primary seals Erosion / Corrosion of primary seals

Primary seals fail under continuous movement

Poor maintenance

Incorrect setting of seals / control systems

Ineffective on-line sealing plate adjustermechanisms


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Problems with primary seals

Actuator

Sector-

plate

Primary

seals

Rotor tyre

Axial seal

plate

Ash

build-up

Rotortyre

Sectorplate


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Are their any solutions ?

YESWe can fit our new sealing system to

ANY OEMs design of air preheater.

Extent of enhancement

Fix all sealing plates

Modernise rotor to double sealing

Use effective leaf seal design

Ensure correct seal settings


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Research & Development


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Element thermal performance

Specific flow before elements Web (Kg/m2.s)

Thermalperformanceperunitlength

7

6

5

4

3

2.78DU

2 3 4 5 6 7 8 9

9.5/3CHB

9.5/3CU

2.5DU

FNC1m1m 1m1m

1m1m


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Double sealing & Fixed sealing plates

Before

After


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Why does double sealing work ?

Single sealed : Pd = Ps1 - Ps2Ps1 Ps2+ve (air)

-ve (gas)

+ve (air) -ve (gas)

Double sealed :

Pd = Ps1 - Ps2 = Ps2 - Ps3

so, Pd acting across each sealis equal to half that for a singlesealed rotor.

Ps1 Ps2 Ps3

reduction..

707.0,2

1

;

,

30%e

PdLPdL

so

PdLLeakage


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How do we operate without Primary seals?

ANSWER -

VN FIXED SEALING


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How do we fix the sealing plates ?

Fully weldedthicker static

primary seal


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Rotor modifications

Before

Typical 24 sector rotor design

After

Rotor modified to 48 sectors

New axial sealcarrying bars fitted


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Double sealing considerations

Cold end elementssupport grid

Cold end elementssupport bars


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Radial and axial seal type


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Reasons for shortfall in performance

Poor sealing system condition

Ingress of air to the boiler

Poor condition of heating surface elements

Higher than design pressure drops due to fouling

Changes in fuel being burned

Off design gas inlet temperatures and flows


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Thermal performance improvements

Sealing system overhaul/enhancement+elimination of internal & external gas & or air

bypass areas

Adoption of higher performance elements

Utilise any additional space in the rotor to

increase the total element height


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Peterhead Preheater Test Results

Parameter Before After

Gas out temp c 131.0 135.3

Air out tempc 285.8 285.8

% Leakage 10.0 5.0

Unit Output MW 630 640

ID fan power kw 2189 2078

ID fan volume m/s 453.2 441.1

ID fan head Mbar 42.1 39.9

ID fan tem c 127 130.8


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Shajiao Power Station, P.R. China


Leakage, % 30 6

Auxiliary Power

(FD & ID) kW

Datum -259

Boiler Efficiency

(fuel/annum) %

Datum +1.0

Tonnes Datum -6220

Unburnt Carbon, % 15 8

Unit output, MW 180 200

20 MW increase !


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Ince Power Station, England


Leakage, % 12 6.5

Boiler Efficiency, % Datum +0.65

Unit output, MW Datum +25Payback on

investment

Less than 2 years


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Peterhead Power Station, Scotland


Leakage, % 14 5

Output, MW Datum +10

Payback 15 Months


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Ensted Power Station, Denmark

Parameter Design Actual

Leakage, % 3.8 2.7

Gas outlet temperature 129.8C 131.8C

Air outlet temperature 309.4C 307.8C

Gas pressure drop 1.22 kPa 1.6 kPa

Air pressure drop 0.85 kPa 0.88 kPaWashing frequency

2 years operation- 6


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Benefits in FGD Plant Design

REHEATER SIZE

Air preheaterleakage, % ReheaterDiameter Price%

25 18m 100

7 16.25m 90

BOOSTER FAN SIZE

Air preheaterleakage, %

FanPower

Price%

25 100% 100

7 86% 66

ABSORBER SIZEAir preheater

leakage, %

25

7

Price

%

100

90


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Reduction in Maintenance

MaintenanceItem

ActuatedSealing

ModifiedSealing

Rotor seals,

actuators, sensors& linkages

100% 50%

Sector & axial

plate seals

100% 10%

Drives 100% 80%All maintenance 100% 60%


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Horizontal heaters

Centre drive unit

Sootblowers

Fire detectionprobes


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Horizontal heaters


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Results

Day 1leakage after

commissioning

or overhaulAdjustable heater

VN sealing


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SUMMARY

Upgrading sealing and reducing

leakage can

Increase MW output Improve boiler efficiency Reduce emissions Reduce fan power Reduce maintenance Reduce FGD plant costs

WITH SHORT PAYBACK PERIODS


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Air Preheater Enhancements

ADDITIONAL ENHANCEMENTS


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Centre drive unit

Centre drive enhancementalso requires replacement ofstub shaft & guide bearing.


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Centre drive unit enhancement : scope of supply

Shrink disk

drive coupling

Worm

gearbox

drive

Shrink diskcoupling

Rolling element

bearing

Cooling waterconnectionsRotor drive

shaft (stub shaft)


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Drive unit view

Gearbox

Shrink disk

coupling

Bearing

housing

Cooling

waterconnectio

ns

Rotor drive

shaft (stub

shaft)

Shrink disk

coupling cover


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Fire detection system


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Fire fighting system


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Fully retractable cleaning device

High pressure waterflexible hose reel

Medium pressure airand Low pressurewater supply line

Air sealed

wallbox collarCleaning Lance Hot End

RotorHeatingElements

( FULLY INSERTED )

( FULLY WITHDRAWN )

HeaterCasing

Cleaning Lance Cold End


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Cleaning Device

Steam

Low / HighPressure

Water or Air


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Benefits of Fully Retractable Sootblower

Maintenance on load gives good availability

Nozzle blockage is minimised

More effective cleaning with steam or aircompared to single nozzle designs

Devices are designed for off line and online high pressure washing


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Information required to prepare proposal

Enhancement Questionnaire

Air preheater design Performance (Test) Data

Operational Experience


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Importance of Site Testing to Selection Process

Site

tests

Analysisof

results

Heaterselection

program

RIGTESTS

BOILERDATA


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Reasons for Performance Testing

To determine performance ofheaters prior to enhancement

To verify heaterperformance forcomparison

with guarantees


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Air Preheater Guarantee Parameters

Thermal Performance

Any one of : Gas exit temperature

Air outlet temperature

Amount of heat transferred

Air to Gas leakage

Any one of :

Percentage of forced draught fan flow

Percentage of gas inlet mass flow O2 differential between gas inlet and outlet flows

Pressure Drop

Air side pressure drop

Gas side pressure drop


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Typical Measurement Instrument Tolerances

Thermal Performance

Gas exit temperature 2C

Air outlet temperature 2C

Amount of heat transferred 5 %

Air to Gas leakage

Percentage of gas inlet mass flow 22 % by O2 readings

O2 differential 0.2 %

Pressure Drop

Air side pressure drop 5 %

Gas side pressure drop 5 %


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Customer satisfaction


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SUMMARY

1. Increase MW output2. Improve boiler efficiency

3. Reduce emissions4. Reduce fan power5. Reduce maintenance6. Reduce FGD plant costs

1. Increase MW output2. Improve boiler efficiency

3. Reduce emissions4. Reduce fan power5. Reduce maintenance6. Reduce FGD plant costs

WITH SHORT PAYBACK PERIODS !

Our Enhancement Package can:-

13aph enhancements

Documents