Fan Retrofit And Enhancement0 pages
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nnnnRETROFITS CAN IMPROVE
nnnnEFFICIENCY, REDUCE NOISE
nnnnAND SAVE MONEY
nnnnHowden
nnnnFAN RETROFIT AND ENHANCEMENT
nnnnHOWDEN KNOW-HOW
nnnnTHERE ARE MANY POSSIBLE REASONS
nnnnFOR FAN RETROFITS. FANS IN POWER
nnnnPLANTS, FOR EXAMPLE, WERE OFTEN
nnnnOVERDESIGNED TO COMPENSATE FOR
nnnnAIR HEATER LEAKAGE. SOMETIMES,
nnnnSYSTEM RESISTANCE WAS SIMPLY
nnnnMISCALCULATED. CHANGES
nnnnOF ALL KINDS IN THE PLANT
nnnnAFFECT THE SYSTEM RESISTANCE.
nnnnFACTORS LIKE THESE HAVE A SERIOUS
nnnnIMPACT ON FAN EFFICIENCY AND
nnnnPERFORMANCE. AND EVEN WHERE
nnnnA FAN MEETS ITS OUTPUT TARGETS,
nnnnNOISE AND VIBRATION CAN CARRY
nnnnHEAVY COSTS AND CONTRIBUTE
nnnnTO MECHANICAL FAILURE.
nnnnTHERE ARE THREE MAIN WAYS IN
nnnnWHICH RETROFITS CAN BE APPLIED
nnnnTO EXISTING FAN INSTALLATIONS.
nnnnTHE FAN PERFORMANCE CAN BE
nnnnOPTIMISED WITHIN THE INSTALLATION.
nnnn• The existing impeller can be replaced
nnnnwith a high efficiency design, allowing
nnnnthe fan to run at its optimum loading
nnnnand highest efficiency.
nnnn• A tip can be added to the existing blade
nnnnto increase performance, typically by
nnnn10-12%. This is a practical way to increase
nnnnthe capacity of an induced draught fan
nnnnto cope with system resistance change.
nnnnCasings, fairings and scrolls can be
nnnnreplaced or modified to improve
nnnnaerodynamics or reduce noise.
nnnn• Inlet cone shape and clearance can
nnnnbe redesigned.
nnnn• The overall system, including the inlet
nnnnbox, RVC and differential louver, can
nnnnbe analysed and optimised.
nnnnTHE EXISTING FAN CAN BE REPLACED
nnnnWITH A DESIGN MATCHED PRECISELY
nnnnTO THE SYSTEM.
nnnn• This is a preferred response to changed
nnnnoperating conditions and a demand for
nnnnextra flow or pressure.
nnnn• It is an effective solution in situations
nnnnwhere severe erosion or corrosion is
nnnnpreventing safe operation of the fan.
nnnnIt is the clear preference where the
nnnnexisting fan is incorrectly matched to
nnnnits situation or application.
nnnnSYSTEM RELIABILITY NEEDS BE
nnnnINVESTIGATED AND IMPROVED.
nnnn• Bearings can be modified to cope
nnnnefficiently with the fan parameters, for
nnnnexample by replacing rolling elements
nnnnwith sleeve bearings to solve problems
nnnnarising from temperature issues.
nnnnOn-line automatic balancing gear can
nnnnbe fitted on a shaft to reduce vibration
nnnnduring operation. This is an effective
nnnnsolution where here is extensive
nnnncorrosion or dust.
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