Overview of Cooling Tower.pdf

7/27/2019 Overview of Cooling Tower.pdf

http://slidepdf.com/reader/full/overview-of-cooling-towerpdf 1/79

COOLING TOWER

Venue :POWER MANAGEMENT INSTITUTE

28 -30-JULY 2008

by

T.P.Chandrawanshi

DGM(OS-BoP)



- • Cooling tower is the most important equipment for closed

cycle water recirculation system.• The efficiency of cooling tower has direct effect on,

station.

• 1oC rise in cold water temperature in a 200MW unit

Rs 50-60 lakhs of loss per annum in terms of direct fuelcost.



-

•

monitoring and its proper operation andmaintenance is ver im ortant for theefficient and economic running of the

plant.• At present about 96 cooling towers are in

operation in NTPC and if only 1 deg. Cent.

mprovemen n co wa er can savecrores of rupees.



TYPES of TOWERS in NTPC

• NATURAL DRAUGHT



Scheme Of O en Recirculatin T e

C.W.System

CONDENSER

BLOW

DOWN

.

HstaticCOOLING

TOWER

C.W.SUMP

-



cooling tower.exe





IDCT Counter Flow





NATURAL DRAFT COOLING TOWERS (4 X 210 MW)



- Total 102 cooling towers installed as given below in

Induced Draught Cooling Towers

• Cross flow type 24

• Counter flow splash bar fill type 24

• Counter flow film fill type 44

Natural Draught Cooling Towers

.(Splash type 8 and Film type 4)

•



COOLING PRINCIPLE

•HOT WATER IS COOLED IN A COOLINGTOWER IN CONTACT WITH COLD AIR

DUE TO:EVAPORATION ABOUT 75%

BY MASS TRANSFER

•SENSIBLE HEAT TRANSFER ABOUT 25%



COOLING PRINCIPLE

MASS TRANSFER IS DUE TOFLOW OF WATER VAPOUR FROM

THE HOT WATER TO THE COLD AIR DEPENDING ON WET BULB

AIR.



COOLING PRINCIPLE

INCREASES AS THE WET BULBTEMPERATURE INCREASES.

• THE FILL WITHIN THE COOLING TOWER IS

THE CRITICAL THERMAL COMPONENT. INWET COOLING TOWERS IT IS THE MEDIUMOVER WHICH THE HOT WATER IS

.PRIMARY FUNCTION IS TO PROVIDE AN

TRANSFER .



FILL IS REQUIRED IN A COOLING TOWER

TO CREATE LARGE SURFACE AREA WHICHPROVIDES NECESSARY TIME OF

CONTACT BETWEEN AIR AND WATER



TYPES OF FILLS

SPLASH TYPE CONSISTING OF SPLASHBARS USED FOR CROSSFLOW AND

COUNTERFLOW.

• FILM TYPE CONSISTING OF THIN

SHEETS USED MOSTLY FOR



SPLASH FILLS

IN SPLASH FILL, THE HOT WATER STRIKES OVER THE BARS AND BREAKSUP INTO MANY SMALLER DROPS.





TYPES OF SPLASH FILLS USED IN NTPC

PROJECTS

• RCC BARS

• PVC PERFORATED V-SHAPED BAR

• PP GRID



TYPES OF SPLASH FILLS

RCC BARS

SPLASH FILL



TYPES OF SPLASH FILLS

PVC PERFORATED V-SHAPED BAR





FILM FILLS

FILM FILL CONSISTS OF FLAT OR FORMED

WHICH WATER AND AIR COME IN CONTACT

STRETCHES DROPLETS OF WATER INTO A

THIN FILMS AS THE WATER PROCEEDS VERTICALLY DOWNWARD THROUGH THECELLS, THEREBY MAXIMIZING THE

SURFACE AREA AND PERMITTING THE AVAILABLE CROSSFLOW OR COUNTERFLOW AIR TO COOL THE ENTIRE MORE RAPIDLY





FILM FILLS

FILM FILL CREATES A VERY LARGE

WATER DISPERSES ITSELF AS A THIN

TRAVELING THROUGH THE TOWER,

COOLING. FILM FILL IS MORE COMPACTTHAN SPLASH FILL AND CAN THEREBY BE MORE COST EFFECTIVE.

















CW PUMPING HEAD REQUIREMENTSFOR DIFF. TOWERS

•ND-SPLASH : 14 M

• ND-FILM : 10 M

• ID- SPLASH : 13 M

• ID-FILL : 9 M







• EFFECT OF FILL HEIGHT IN CT DESIGN

IF HEIGHT IS RESTRICTED TO APARTICULAR VALUE AIR FLOW IS TO BEINCREASED WHICH REQUIRES HIGHER

POWER CONSUMPTION. OTHERWISEPLAN AREA TO MAINTAIN FILL VOLUMEIS TO BE INCREASED WHICH CALLS FOR

.









•

NEW FILM FILLS HELP REDUCE OR ELIMINATE THE PROBLEM. GENERALLY,

AND THE CORRUGATIONS TEND TO BE.

VELOCITY APPEARS TO BE SIGNIFICANT IN

THE FILL SURFACE.











C f CT P P f



Cause of CT Poor Performance

6. Chocking of nozzle by OLTC balls.

. .

8. Hot water distribution pipe.

9. Fill clogging

. e .

11.Lot of trees/plants/bushes growth near

12.Poor quality of water (make-up)



Optimizing CT Performance



Optimizing CT Performance.

• Cleaning of civil structure annually and removal of algae from DE,Fills.

• Fan door and an other air in ress oint to be sealed.

• Regular condition monitoring of CT fans.

• Continuous chlorine dosing to be done.• Sludge disposal pump to be run once in a day minimum for 15

m nu es.

• Monthly checking of effectiveness of tower for comparisonpurpose and once checking of perf. during mansion as per OGN.

•about 1.5 meter height and both side about 2 meter wide brickpaving to be done to avoid any plant growth

• At CT outlet screen to be provided to remove any debris, plastic.

• To protect OLTC balls and any other material going to nozzles;nozzle protector to be provided which is a hollow steel pipeinserted into H.W.D. pipe with wire mesh.



• Fill clo in and su ort structure failure

• Sagging of PVC Drift Eliminators in counter flowtype: It has no support in between.

• ACB hot water distribution pipe failure.

• Growth of trees/bushes/plants near CT after c ean ng aga n an aga n.

• Civil structure reinforced steel exposed

o a mosp ere.• Algae growth in CT structure.







Best Practices in NTPC

• Quarterly film fill pack weight is taken to know the clogging status

during PM (Rihand, Sipat)

• All around CW-OAC, brick paving is done for about 4 meter and

nylon net is placed over to avoid growth of plants near POAC andfalling of suspended particle in OAC.

• At CT outlet screen is provided to remove any debris, plastic pieces

falling into the cold water basin.(Kh, TTPS)

• Civil structure is cleaned by bleaching powder during PM to keep itfree from algae (Rihand)

• To arrest the OLTC balls from going to nozzles, nozzle protector

sleeve with mesh is provided in hot water distribution pipes (RSTPP)

• CW duct cleaning and painting done in all 6 units of ST-I (VSTPP)



Algae Growth in the Intake Channel



Algae Growth in the Intake Channel

at Jhanor Gandhar

Al ae rowth

View of Chocked & clean PVC fills



e o C oc ed & c ea C s

Chocked PVC Fills



Deposited dust

articles



Deposited

dust articles



Clogging Of Fill Packs-TSTPS-II



gg g

Clogged Fills

PVC fill pack sagging-TSTPS-II



PVC fill pack sagging-TSTPS-IIxcess ve we ginitiating bending

of SS Supports

Sagging of SS supports of PVC fills



Sagging of SS supports of PVC fills

at TSTPS-II

PVC Fills resting on RCC beams after



PVC Fills resting on RCC beams after

sagging at TSTPS-II









Hub Seal Disctte tg-













PVC Fills resting on RCC beams



& temporary supports given







Hub Seal Disctte tg-





To be sealed

properly



Documents

Overview of Cooling Tower.pdf