advanced sootblowing strategy using smartsootblower€¦ · advanced sootblowing strategy using...

© CBPG Clyde Bergemann Power Group 12.2005 - Rev. 10

Advanced Sootblowing StrategyUsing SmartSootblower

Danny TandraClyde Bergemann, Inc

Steam & Steam Power and Energy Cost Saving CommitteesPAPTAC

December 12 - 13, 2006

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Fouling

Plugging

Images are from the work of The University of Toronto – Pulp & Paper Centre

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Expectation Gap

Expectation

Current Sootblower Technology

Sootblower Performance

High Steam Consumption

SmartSootblowerTargeted Cleaning

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Background

The flow of a sootblower jet is supersonic (Mach ≈ 3)

“Flow disturbance” in the form of a shock wave is formed if a supersonic flow impinges on a solid object and is brought to a complete stop.

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Pitot tube immersed in stream of a supersonic flow

Mach = 1.5

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Sootblower Jet

Potential Core Supersonic region

Subsonic region

Platen - 1

Offset

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Background

The position of sootblower nozzles with respect to boiler banks has been known to have a great effect on the ability of the jet to exert force on deposits.

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Platen

PlatenPlaten

Platen

Platen

Platen

Sootblower needs to be designed in such a way that we may have the full knowledge on where the sootblower nozzles are positioned with respect to the boiler banks and full control on

the helix movement of the lance (Targeted Cleaning).

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Conventional Sootblower

Conventional sootblowers clean the heat exchanger tube surfaces with little or no knowledge of where the nozzles are positioned with respect to the boiler banks.

Helical motion of a conventional sootblower

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Conventional Sootblower

The helical movement produced by the conventional sootblower cannot be easily adjusted, which makes the sootblower cleans the entire tube surfaces with even intensity (over cleaning in some areas and under cleaning in others).

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Conventional SootblowerDownstream nozzle

no offset

Stroke I Stroke II

Stroke I: The sootblower jet is in direct collision with the boiler tube.In this case, the jet will not be able to penetrate deep into the bank

and exert significant force on the deposit.

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Advanced Strategy

SmartSootblower (DualMotor Sootblower) is equipped with two motors that independently control the transversingand rotating motion of the lance tube.

This independent movement of the lance allows the sootblower nozzles to be positioned in such a way as to minimize the jet-tube interaction, hence dedicating all the jet power to remove deposits.

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Targeted Cleaning

Dual motor

Conventional Sootblower

Stop & Rotate in the problematic area Long helix in the

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SmartSootblower & Low Pressure

Sootblowing Technology

to combat plugging in Recovery Boilers

and save energy

© CBPG Clyde Bergemann Power Group 12.2005 - Rev. 10

Low Pressure Sootblowing Technology

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HistoryIdea was originated from

A Pulp & Paper Consortium Meeting in 2001Organized by University of Toronto, Canada.

Boiler ManufacturersAlstom Power Inc.Andritz OyBabcock & Wilcox CompanyKvaerner Pulping Oy

Sootblower ManufacturerClyde Bergemann, Inc.

Pulp & Paper CompaniesAracruz Celulose S.A.Boise Cascade Corporation

Pulp & Paper CompaniesBowater Canadian Forest Products Inc.Daishowa Marubeni International Ltd.Domtar Inc.Georgia-Pacific CorporationInternational Paper CompanyIrving Pulp and Paper LimitedMeadWestvaco CorporationStora Enso Research ABTembec Inc.Votorantim Celulose e PapelWestvaco CorporationWeyerhaeuser CompanyWillamette Industries Inc.

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MotivationRecovery

Boiler

Steam Turbine

Poppet valve

Sootblowers~ 300 psig

High pressure steam600 -1500 psig

Low pressure steam to mill processes150 - 200 psig

Pressure Reducing Station

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Low Pressure SootblowingRecovery

Boiler

Steam turbine

Sootblowers150 - 200 psig

High pressure steam600-1500 psig

Low pressure steam to mill processes150 - 200 psig

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IncentiveUse less valuable-lower pressure steam for sootblowing.

Energy Savings:

Lower maintenance costs

Less noise

Longer jet penetration (> cleaning coverage)

High pressure sootblowing (900 psig ==> PRV => 300 psi )

Low pressure steam (150 - 200 psi)

Dollar saving = Difference in the steam cost

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Can low pressure steam provide a comparable amount of cleaning power as the high pressure steam ?

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Deposit removal mechanism

Deposit will be removed from the tube surface if

Fjet > Sadhesion. A contact area

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In order for the Low Pressure Jet to achieve the same cleaning power as the High Pressure Jet, the LP sootblower has to be designed to produce a comparable amount of force as the HP sootblower.

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Low Pressure BlowingCan low pressure steam provide a comparable amount of force as the high pressure steam ?

Fjet (Low Pressure) = Fjet (High Pressure)?

ή. M(lb/s). Vjet(ft/s)|LP = ή. M(lb/s). Vjet (ft/s) |HP?

Vjet |LP is always less than Vjet|HP

the flow rate M(lb/s) and nozzle efficiency (ή ) of LP have to be increased to match the force of HP.

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LP vs HP: A comparisonLP has larger nozzle Longer Jet PenetrationCFE-Low PressureBigger NozzleHigher nozzle efficiency: 4” lance tube

High Pressure Nozzle

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LP vs HP: A comparison

PIP (psi)

Deposit-Jet contact area (in2)

Peak Impact Pressure (PIP) of HP

PIP of HP > PIP of LP, but the area under the curve(force) => comparable.

The HP pushes the deposit with concentrated sharp jetwhile LP pushes the deposit with bigger and lessconcentrated pressure.

Peak Impact Pressure of LP

F = P (lbf/in2) . A (in2)

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Conclusion

Fluid Dynamic theoretical analysis supported by laboratory experiments, and CFD analysis suggest that LP sootblowing is feasible.

The capability of LP sootblower to control deposit accumulation has been confirmed by the success of the LP Field trial at Irving Pulp & Paper, Saint John, Canada.

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CB Low Pressure Installation

CB supplied LP sootblowers to a newly built Andritz Boilers:

• Weyerhaeuser Valliant, OK, USA (2005)

• Weyerhaeuser Campti, LA, USA (2006)

4” OD lance tube with two CFEIII LP nozzles are used.

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SmartSootblower & Low Pressure

Sootblowing Technology

to combat plugging in Recovery Boilers

and save energy

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Plugging Process

Flue gas

Flue gas

Flue gas

Flue gas

Flue gas

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Conventional Strategy

Windward

Flue gas

Leeward

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Advanced Strategy

Flue gasWindwardLeeward

Deposit

Leeward Windward

Minimize Jet-tube interaction by properlypositioning the nozzle – SmartSootblower.

Long jet penetration – Low Pressure Jet

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It has been known that the position of sootblower nozzles with respect to the boiler bank has a great effect on the ability of the jet to remove deposits.

The increase in sootblowing intensity using conventional sootblowers to combat local boiler fouling & plugging can promote sootblower-induced-tube-erosion (over cleaning in one area and under cleaning in others).

Summary

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SmartSootblower was developed with the main objective to suppress the jet-tube interaction and promote targeted cleaning by adjusting the sootblower transverse & rotational movements.

Low Pressure Sootblower, which has the capability to form a longer penetration jet, can be installed in the SmartSootblower to combat plugging and save energy.

Summary