ENERGY CONSERVATION STRATEGIES IN COOLING

TOWERS

A Presentation by

Kunal Mukherjee

Vice President (South)

ENERGY CONSERVATION STRATEGIES IN COOLING

TOWERS

A Presentation by

Kunal Mukherjee

Vice President (South)

ENERGY CONSERVATION CHALLENGES

Optimal energy consumption during Cooling Tower operations

ANDAND

Efficient cooling performance to fac

ENERGY CONSERVATION CHALLENGES

Optimal energy consumption during Cooling Tower operations

ANDAND

facilitate process energy efficiencies

THE COOLING TOWERTHE COOLING TOWER

ENERGY CONSERVATION AVENUES1. WATER HANDLING ARRANGEMENTS

2. AIR HANDLING ARRANGEMENTS

3. HEAT TRANSFER SURFACES

4. DRIVE ARRANGEMENTS

ENERGY CONSERVATION AVENUESWATER HANDLING ARRANGEMENTS

AIR HANDLING ARRANGEMENTS

WATER HANDLINGIF WATER DISTRIBUTION IS NOT UNIFORM

IT MAY NOT AFFECT THE POWER CONSUMPTION OF THE COOLING TOWER

BUT

IT WILL AFFECT THE COOLING PERFORMANCE AND YIELD WARMER WATER

WHICH IN TURN

WILL AFFECT THE PROCESS EFFICIENCY

RESULTING IN

INCREASED ENERGY DEMAND FOR THE SAME PROCESS OUTPUT

WATER HANDLINGIF WATER DISTRIBUTION IS NOT UNIFORM

IT MAY NOT AFFECT THE POWER CONSUMPTION OF THE COOLING TOWER

BUT

IT WILL AFFECT THE COOLING PERFORMANCE AND YIELD WARMER WATER

WHICH IN TURN

WILL AFFECT THE PROCESS EFFICIENCY

RESULTING IN

INCREASED ENERGY DEMAND FOR THE SAME PROCESS OUTPUT

WATER HANDLING

properly designed

contribute tocontribute to

Thermal Performance

% in a typical

Cooling Tower.

WATER HANDLING

designed nozzle could

improving theimproving the

Performance by up

typical film-fill type

AIR HANDLINGIMPROVEMENTS / OPTIMISA

ADJUSTMENT OF BLADE PITCH ANGLE

USE OF VELOCITY RECOVERY FANDROP

CHANGE TO HIGHER RATEDCONFIGURATIONS

AIR HANDLINGISATION POSSIBLE THROUGH

ANGLE FOR SUPERIOR AIR DELIVERY

FAN CYLINDERS TO REDUCE PRESSURE

RATED AND/OR SPECIAL MOTORS

AIR HANDLINGAIR HANDLING

AIR HANDLINGTip Clearance Optimise to reducetake care to avoid mechanical interferenceexpansion of blades. Also Fancontracta create additional turbulencedropdrop

Vertical Location of Fan Planeallowing formation of vertical streamto contact with fan blades

Velocity Recovery Fan Stack To harnessvelocity pressure and minimizingoptimization also necessary to minimize

AIR HANDLINGreduce creation of air-vortex at tips BUT

interference especially due to thermaltips operating beyond the vena

turbulence and hence increase pressure

To maximize air-travel distancestream (for minimum energy loss) prior

harness the venturi effect, reducingstatic pressure drop. Stack height

minimize dead-load & wind load

HEAT TRANSFER SURFACESCooling tower works on the principle

The more efficiently it can extractthe more efficient the cooling tower

The fill surface is designed tomaximize heat transfer from everymaximize heat transfer from every

The fill configuration, design anddroplet profile inside the cooling tower

By maximizing the heat transfer areaevaporative cooling is achieved withair ..

And hence, optimize operating

HEAT TRANSFER SURFACESprinciple of evaporative heat transfer

extract heat from each droplet of water,tower is

manipulate input water flow toevery micro-droplet thereofevery micro-droplet thereof

wet-behavior optimizes the watertower

area achieved by each water droplet,with the minimum quantum of input

energy

HEAT TRANSFER SURFACESHEAT TRANSFER SURFACES

HEAT TRANSFER SURFACESWOOD

FLOW (USGPM) 15000

HWT (OF) 115HWT ( F) 115

CWT (OF) 90

WBT (OF) 78

FAN BHP 165

SAVINGS IN CONSUMED POWER > 18%

HEAT TRANSFER SURFACESWOOD LATH PVC V-BARS

15000 15000

115 115115 115

90 90

78 78

165 135

SAVINGS IN CONSUMED POWER > 18%

DRIFT ELIMINATORTO REDUCE DRIFT ANDPRESSURE DROP

TYPICAL TYPES WOOD LATH,TYPICAL TYPES WOOD LATH,EXTRUDED PVC, CELLULAR PVC

OPTIMAL CONFIGURATION LAST PASS SHOULD DIRECT AIRUPWARDS TO THE FAN TOAVOID FAN PLENUM LOSSES UPTO 8-10%

DRIFT ELIMINATOR

DRIVE ARRANGEMENTSUSE OF AUTOMATED ON-OFF CONTROLDESIRED RANGE

USE OF DUAL SPEED MOTOR BETTERLOADS

USE OF AUTO VARIABLE SPEED DRIVEFREQUENCY

DRIVE ARRANGEMENTSCONTROL MAINTAIN CWT WITHIN

BETTER UTILISATION OF OFF-SEASON

DRIVE AIR FLOW QQQQ RPM QQQQ SUPPLY

FAN POWER FACTS & FICTIONTHE FAN POWER EQUATION IS

FHP = V x Pt / (6356N), wherewhere

FHP = FAN HORSE-POWER

V = AIR FLOW RATE IN CFM

Pt = FAN PRESSURE DROP IN inWC

N = FAN EFFICIENCY

FACTS & FICTIONAGAIN, Pt = Ps + Pv, WHERE

Ps = STATIC PRESSURE

= f(CFM, CT Model)

Pv = VELOCITY PRESSUREPv = VELOCITY PRESSURE

= f(CFM, NDA)

THEREFORE FHP = f(CFM, N, NDA, CT Model), WHERE AGAIN

CT MODEL DEFINES THE HEAT TRANSFER CHARACTERISTICS

FAN POWER FACTS & FICTIONTHE POWER AT MOTOR TERMINALSLOSSES

ENTRY LOSS

SKIN FRICTIONAL LOSSSKIN FRICTIONAL LOSS

TIP CLEARANCE LOSS

TRANSMISSION LOSS (FOR GRDR /

MOTOR EFFICIENCY

BEARING LOSS

OF THESE, ONLY BEARING LOSS DEPENDS ON THE WEIGHT OF THE FAN

FACTS & FICTIONTERMINALS CONSIDERS THE FOLLOWING

BELTS)

OF THESE, ONLY BEARING LOSS DEPENDS ON THE WEIGHT OF THE FAN

FAN POWER FACTS & FICTION

Weight of each blade

Number of blades

Total blade weight

Weight of Fan HubWeight of Fan Hub

Total weight of Fan assembly

Co-efficient of friction for simple ball-bearing

Drive shaft diameter

Fan speed

Bearing Loss

THE FHP IN THIS EXAMPLE WAS 39 WHICH MEANS THE ADDITIONAL BEARING LOSS WAS ONLY

0.27%

FACTS & FICTIONALUMINIUM FRP

Kg 20 16

8 6

Kg 160 96

Kg 200 200Kg 200 200

Kg 360 296

Co-efficient of friction for simple ball-bearing 0.0015 0.0015

cm 10 10

RPM 260 260

HP 0.588 0.484

THE FHP IN THIS EXAMPLE WAS 39 WHICH MEANS THE ADDITIONAL BEARING LOSS WAS ONLY

0.27%

FAN POWER FACTS & FICTIONCLAIM : 30% REDUCTION IN FAN PO

Suppose original Fan efficiency = 75%

For 30% reduction in fan power, efficiency of new fan has to be =For 30% reduction in fan power, efficiency of new fan has to be =

0.75 x (1/0.7) = 1.07

i.e. 107%

FACTS & FICTIONN POWER WITH SAME AIR DELIVERY

Suppose original Fan efficiency = 75%

For 30% reduction in fan power, efficiency of new fan has to be =For 30% reduction in fan power, efficiency of new fan has to be =

0.75 x (1/0.7) = 1.07

i.e. 107%

FAN POWER FACTS & FICTIONCLAIMS OF 25-30% REDUCED FANNEW-AGE HOLLOW FRP BLADESSOME

USUALLY FAN CHANGES ARE MADETESTING OF SUCH CLAIMS IS DONEFITTINGFITTING

FAN CFM IS ADJUSTED TO CLAIMEDANGLES

SINCE WBT IS LOWER THAN DESIGNTOWER PERFORMANCE IS FOUNDCFM

FACTS & FICTIONFAN POWER CONSUMPTION BY USING

IS A SCAM BEING PERPETRATED BY

MADE DURING OFF-PEAK SEASONS ANDDONE IMMEDIATELY AFTER RETRO

CLAIMED BHP BY ADJUSTING PITCH

DESIGN WBT AT THIS TIME, COOLINGFOUND SATISFACTORY EVEN WITH LOWER

FAN POWER FACTS & FICTION IT IS ONLY DURING THE NEXT

TOWER PERFORMANCE INADEQUACIES

EMERGENCY CORRECTIVE ACTION

BLADE PITCH ANGLES WITH

INCREASESINCREASES

SUCH SITUATIONS ARE RARELY

UTILITIES ENGINEER, OR EVEN

ADMIT TO HAVING BEEN THE

TECHNOLOGY SCAM ?

FACTS & FICTIONNEXT SUMMER SEASON THAT

INADEQUACIES GET NOTICED

ACTION IS TAKEN BY ADJUSTING

WITH WHICH CONSUMED POWER

RARELY HIGHLIGHTED WHICH

EVEN CHIEF ENGINEER, WILL EVER

THE VICTIM OF AN ELABORATE

Mr. G. Venkataraman @ 99401

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99401 31973

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