Dry Cooling Tower

8/3/2019 Dry Cooling Tower

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Air Cooled Condensor/adp 1

PLEASE REMEMBER

Only 2.5 % of the world’s water is fresh water.

And a tiny fraction (0.007%) of all water on earth

is accessible for direct human uses.

Wet Condenser cooling for 1000 MW plant

requires 3000 M3/ Hr water,which can feed Rural Population of ONE

Million.

WHY WATER CONSERVATION ?




Please Ponder

Power generators will benefit by water conservation

as local & regional supplies will last longer.

So future plant operation will be guaranteed.

Accelerated approval of construction permit.

Shortened project schedule.(No large barrage &

Pipelines or canals for raw water )Better economics and Siting options.




WATER WILL BE SCARCE & COSTLY

As water will become scares & costlier,TPS may be

compelled to go for RETROFIT dry cooling towers.

This will be an avoidable extra cost.

Dry cooling worldwide has grown 20 times in last 5years.

China already has 30,000 MW Dry cooling installations.

As per National Policy , USA is adopting Dry Cooling

Systems even for Non-Arid Regions.




V I D A R B H AJust think about 35000 – 40000 MW upcoming

Thermal Projects in Vidarbha.

H.C.S.D. system for ash disposal and

Dry Cooling can ensure water supply forDRINKING AND IRRIGATION

in this dry area.

The State can have POWER and save preciouswater for Drinking & Irrigation.

Water pollution will greatly reduce.




Water needs of a Thermal Power Station

A 210 MW TPS needs water for-

1. Boiler water make-up (D.M. Water-25 M3 / Hr)

2. Drinking Water ( 5.0 M3 / Hr)

3. Water for Wet Ash Handling – (750 M3 / Hr)

4. Cooling Tower water Make-up – ( 650 M3 / Hr)

5. Service Water – ( 10 M3 / Hr)

6. Total = 1440 M / Hr.




Air Cooled Condensor

A T.P.S. needs large quantity of Cooling Water.

Recently, during last summer(2010), six units of Chandrapur TPS were shut down due to water shortage.

Also, water is getting costlier and scarce.

An air cooled condenser overcomes these limitations.Site restrictions are also overcome.

No expenditure on chemicals for water treatment.

Life time cost of a dry cooling tower is surely less than

conventional evaporative cooling tower.

Dry cooling tower cost may be 2.5 times that of a

conventional evaporative cooling tower.




H.C.S.D. FOR WATER CONSERVATION

Typical lean slurry disposal has slurry

concentration of 15-20 % only.(20% ash in slurry).i.e. 100 M.T. of ash needs 400 M3 of Water.

But High Concentration Slurry Disposal system

need only 65-70 M3 of Water for 100 MT ash.

A reduction of 330 M3 of water consumption for

100 MT of Ash.

MORE THAN 80% SAVING OF WATER.

HCSD system is running successfully at

Khaperkheda TPS for last 11 years.




COOLING TOWER MAKE-UP

Conventional Cooling Tower cools the water byEvaporative Cooling.

Hourly evaporation = Hourly steam flow to condenser.

In addition, there are 2-3 % drift loss and

Blow down loss to maintain water quality.

The DRY AIR COOLING eliminates this water

consumption almost totally.

The make up reduces by 95 % or more.




Forced Draft Dry C.T.




Site selection and water clearances

The pragmatic developer may select dry cooling early in

a project because,

It increases plant siting options and,

Its use can significantly accelerate approval of

construction permits,

Because water use issues are taken off the table.

Shortening a project schedule by even six months can

completely change the economics of a project and,Easily balance the increased capital cost of dry cooling

options




Examples of EXTRA COST

1. Parli TPS – Huge barrage on Godavari and two

stage pumping of water. Reservoir at Naikotwadi.2. Paras TPS – Barrage.

3. Koradi & Khaperkheda TPS – 7 day reservoir and

22 Km long pipe line of 1600 mm dia.Bridges onKolar & Kanhan rivers.

4. Also construction of Salt Lagoons at all power

stations and Soften Water plants.

5. Chlorination plants. (Ozonization Plants.)

6. Serious damages to Cooling Towers and repair costs

at Nasik & Koradi TPS.




Some Costing

Evaporative Cooling Tower- 270 MW unit – 22.0 Crores

Total Plant cost – 270 x 6.0 =1620.0 Cr.Dry Cooling Tower – 22 x 2.5 = 55.0 Cr.

Extra expenditure = 33.0 Cr.only

Salt consumption 2000 MT/Yr, @ Rs.2000 /MT,Cost Rs.40 lakhs/year.

25 years cost = 10 Cr.

There is saving in cost of salt lagoons, Godowns,

Softening plant etc.

Huge saving in annual cost of water itself.(Next slide)

No blow downs and water pollution.




COST OF MAKE-UP WATER

Unit Capacity MW 210 270 300 500 660

C.W. Make-up M3/Hr 500 643 714 1190 1571

ANNUAL-CW Make-up

in Mn. M34.38 5.63 6.26 10.43 13.77

Plant PLF 0.90 0.90 0.90 0.90 0.90

NET ANNUAL-CW

Make-up Mn. M33.94 5.07 5.63 9.39 12.39

RATE-Rs./Cub.Mtr 5 5 5 5 5

ANNUAL COST OFWATER in Rs.Cr

1.97 2.53 2.82 4.69 6.19

Water cost may escalate @ 4-5 % per year.




Life Cycle Cost

Considering all the costs,

HELLER cooling system cost can be as low as2/3rd of Conventional Wet Cooling System.






Natural Draft Dry Cooling Tower




Dry Steam Condenser or Dry C.T.

Steam may be condensed in the cooling tower .

OR,A surface(or Jet) condenser may be used and the

cooling water is cooled in the dry C.T.

In both cases Evaporative Water Loss is eliminated.Because the water circuit is a closed one and there is

no loss.

Just consider a modern car.Earlier the radiator had to

be topped up daily.

Now, one can travel thousands of miles without

topping up the radiator.




FREE COOLING

. An indirect dry-cooling system was installed at the 6 x

686-MW power plant in Kendal, South Africa.In this cooling system design, water is circulated from a

standard condenser to the tower, where it enters a series

of heat exchange elements on the base.

Air enters the bottom periphery of the tower, passingover heat exchange elements.

The heated air rises inside the tower, pulling in more cool

air.No fans are required.




Waterless condensing

Steam enters the air-cooled condenser at the top

(blue pipe) of the heat exchangers,flows downward through the heat exchanger

tubes,

and it condenses and is captured in pipes at thebase of the heat exchangers.

The condensate is then returned to the boiler

water system.Mechanical fans force air over the heat

exchangers.




DRY COOLING MAY BE N.D.C.T. OR I.D.C.T.

Heller system is an indirect dry cooling plant.

The Power Plant Waste Heat is initially transferred in

a Condenser (Preferably Jet Type) to a CLOSED

C.W.Circuit.

Heat pick-up by the C.W. Water is rejected to

Ambient Air in FIN TUBE type heat exchanger.

Air moving can be either Natural or Forced.

i.e. N.D.C.T. OR I.D.C.T.




Initial Temperature Difference

I.T.D. is the Temperature difference between CONDENSING

STEAM and Ambient Air.I.T.D. is the driving force for Heat Transfer in Dry Cooling.

Typical ITD value range : 28 – 36 Deg.C.

The difference between ITD values of DC Jet Condenser and

Surface Condenser is : 3.5 – 4.5 Deg.C.

This is about 15 % of the Driving Force.

Therefore, Dry Systems with SURFACE CONDENSER need a

LARGER COOLING TOWER.

[ water flow rate, heat exchanger surface area, mechanical

equipment,and civil construction.]

L t D C l d CCPP 3 770 MW GEBZE &




Largest Dry Cooled CCPP – 3 x 770 MW – GEBZE &

ADAPAZARI – 2002 – TURKEY.




HELLER SYSTEM (With Supplemental Spray)




Heller System (With assisting wet cells)




200 MW Trakya CCPP, Turkey (ABB)




2 x 600 MW coal fired – Yangcheng P.S. China.




Russia : Strogino Co-Gen CCPP , 2 x 200 MW. With

supplemental spray.




Modugno CCPP 800 MW, Italy (2008) IDCT.




Modugno CCPP 800 MW, Italy (2008) IDCT.

front view

































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Dry Cooling Tower