Fan Retrofit And Enhancement0 pages

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www.howden.com

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RETROFITS CAN IMPROVE

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EFFICIENCY, REDUCE NOISE

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AND SAVE MONEY

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Howden

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FAN RETROFIT AND ENHANCEMENT

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HOWDEN KNOW-HOW

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THERE ARE MANY POSSIBLE REASONS

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FOR FAN RETROFITS. FANS IN POWER

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PLANTS, FOR EXAMPLE, WERE OFTEN

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OVERDESIGNED TO COMPENSATE FOR

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AIR HEATER LEAKAGE. SOMETIMES,

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SYSTEM RESISTANCE WAS SIMPLY

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MISCALCULATED. CHANGES

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OF ALL KINDS IN THE PLANT

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AFFECT THE SYSTEM RESISTANCE.

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FACTORS LIKE THESE HAVE A SERIOUS

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IMPACT ON FAN EFFICIENCY AND

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PERFORMANCE. AND EVEN WHERE

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A FAN MEETS ITS OUTPUT TARGETS,

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NOISE AND VIBRATION CAN CARRY

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HEAVY COSTS AND CONTRIBUTE

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TO MECHANICAL FAILURE.

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THERE ARE THREE MAIN WAYS IN

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WHICH RETROFITS CAN BE APPLIED

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TO EXISTING FAN INSTALLATIONS.

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THE FAN PERFORMANCE CAN BE

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OPTIMISED WITHIN THE INSTALLATION.

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• The existing impeller can be replaced

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with a high efficiency design, allowing

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the fan to run at its optimum loading

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and highest efficiency.

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• A tip can be added to the existing blade

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to increase performance, typically by

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10-12%. This is a practical way to increase

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the capacity of an induced draught fan

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to cope with system resistance change.

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Casings, fairings and scrolls can be

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replaced or modified to improve

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aerodynamics or reduce noise.

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• Inlet cone shape and clearance can

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be redesigned.

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• The overall system, including the inlet

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box, RVC and differential louver, can

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be analysed and optimised.

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THE EXISTING FAN CAN BE REPLACED

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WITH A DESIGN MATCHED PRECISELY

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TO THE SYSTEM.

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• This is a preferred response to changed

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operating conditions and a demand for

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extra flow or pressure.

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• It is an effective solution in situations

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where severe erosion or corrosion is

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preventing safe operation of the fan.

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It is the clear preference where the

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existing fan is incorrectly matched to

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its situation or application.

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SYSTEM RELIABILITY NEEDS BE

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INVESTIGATED AND IMPROVED.

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• Bearings can be modified to cope

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efficiently with the fan parameters, for

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example by replacing rolling elements

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with sleeve bearings to solve problems

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arising from temperature issues.

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On-line automatic balancing gear can

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be fitted on a shaft to reduce vibration

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during operation. This is an effective

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solution where here is extensive

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corrosion or dust.

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