Energy Efficient Techniques for Air Preheater · Firing poor quality coal makes the layers of APH...

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www.geeco.in GEECO Enercon Pvt Ltd.,

Energy Efficient Techniques

for

Air Preheater

Presented by:

V.Rajagopal

GEECO, Trichy, India

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Designation of Air Preheater

29 VI T SM RC 78 (82)

Size of APH

VI - Vertical Inverted

Tri - Sector

Element Depth, in

inches Semi Modular Future Element

Round Casing

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LAP 13494 / 1800

Ljungstrom

APH

Diameter of Rotor,

mm

Element Depth, mm

Designation of Air Preheater

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• The efficiency of boiler is increased by reduction in Gas Outlet Temperature (for every 20°C drop in flue gas temperature, the boiler efficiency increases by 1%). Leads to fuel saving.

• Reduction of APH leakage decreases Fan loading. • Reduced Gas outlet temperature reduces flue gas

volume and that results in improving ESP efficiency.

Role of Air Preheater in a Boiler

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Innovative Concepts

Resulted in • Improved Thermal Performance • Improved Fan Margin • Increased Reliability in operation • Less down time and Increased availability of

Air preheater • Less Maintenance cost • Increased Life of APH Internals

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Profiles

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Conventional Element Profiles

Double Undulated (DU)

Notched Flat (NF)

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Conventional Element Profiles

FNC

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Conventional Element Profiles

DUN

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Upgraded Heating Element Profile

Recent times the quality of coal has deteriorated – Low Calorific Value, High Ash and Sulphur.

Firing poor quality coal makes the layers of APH heating elements susceptible to fouling. Hence, there is a need to upgrade profile to minimise

fouling with consistent performance.

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Upgraded Heating Element Profile

* GEECO’s answer is the modified and improved profiles.

* The results are verified by CFD simulations & Wind

Tunnel Testing

* Implemented and the results confirms to CFD and Wind Tunnel Testing

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Upgraded Heating Element Profile

Solution for Improved Thermal Performance

GHT®

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Equal thermal performance

Lower pressure drop

6% higher heat transfer area

Reduced fouling or choking

Easy to clean under soot blowing

operation

Sustained performance

Increased life

Short Payback

MERITS of GHT® over FNC

Upgraded Heating Element Profile

FNC

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Herringbone Profiles

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AREA REDUCTION DUE TO CLEARANCE BETWEEN BASKETS & DIAPHRAGM PLATES

APH : 27 VIT DOUBLE SEALING IF GAP BETWEEN DIAPHRAGM PLATE & BASKETS IS 20mm ON BOTH SIDES:

REDUCTION IN AREA : 4.94%

IF GAP BETWEEN DIAPHRAGM PLATE & BASKETS IS 10mm ON BOTH SIDES: REDUCTION IN AREA : 2.46%

Dimensioning of Baskets

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Increase in Heat Transfer Area

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Increasing the height of APH to accommodate

Increase in Element height from 57.5’’ to 67.5” (1460 to 1715 mm)

Increasing the Size of APH

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Increasing the Size of APH

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Increasing both diameter and

height of Rotor

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Solution for Improved Thermal Performance @ lesser DP

MAXTRA®

Increasing the Size of APH

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Maxtra resulted in improving the boiler efficiency from 1.5 to 2%

Maxtra resulted in reducing the leakage level

Maxtra

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Placement of Bigger Size APH in

3rd Pass of the Boiler

Maxtra

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Maxtra

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CFD

Computational Fluid Dynamics

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Even distribution Gas and Air

at Entry

CFD

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CFD

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Flue Gas Inlet – Velocity Magnitude

Large flow Separation downstream of the

ash hopper that creates an uneven

flow distribution

Reduced the flow Separation

downstream of the ash hopper by addition of a

guide deflector vane

Added Vane

47

CFD

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Introduction of Sacrificing

Baskets at Gas Entry

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Sacrificing Element

Hot Intermediate

Hot End

Cold End

Sacrificing Baskets

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Soft Touch Seal

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Soft Touch Seal

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Liner Plate on Sealing Surface

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Liner Plates

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Single Sealing

----

Double Sealing

----

Triple Sealing

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Solution for Reduced Leakage and Improved Fan Margin

DOUBLE / TRIPLE SEALING

MODIFIED RADIAL AND AXIAL SEALING

ARRANGEMENT WITH MODULAR ROTOR

Improvements

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Before Typical 12 sector rotor design

After Rotor modified to 24 sectors

New axial seal carrying bars fitted

Improvements

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Modular Rotor

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Modular Rotor

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Leakage Control System

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Solution for Reduced Leakage and Improved Fan Margin

GLRS®

LEAKAGE CONTROL SYSTEM

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Talcon Seal

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Solution for Increased Reliability

PERIPHERAL DRIVE SYSTEM

INTRODUCTION OF PERIPHERAL DRIVE SYSTEM

FOR AIR PREHEATERS

Reliability

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Solution to prevent more ash carry over to Air Preheater

ECO - HOPPER

Reliability

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Solution for Increased Reliability

APH MONITORING SYSTEM

SCADA BASED ONLINE APH PERFORMANCE

MONITORING & FIRE SENSING SYSTEM

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Solution for Increased Reliability

Conversion of TAPH to RAPH

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Thank You