Water use in nuclear & coal-fired power generation

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Could somebody give me some ballpark figures about water use in large nuclear & coal-fired power generation plants. Are there any benchmark figures, such as tonnes of water use per GW and hour of operation? What temperature increase can be expected in water temperature between water intake and after the cooling tower?


Ballpark figures for plants built in the late 1970’s:

  1. Coal , subcritical , steam turbine cycle heat rate = 7961 btu/kwhr ( 42.86% efficient, 57.14% of steam energy discharged to cooling tower)

  2. Nuclear turbine cycle heat rate about 10,623 btu/kw hr (32.12% efficient, 67.88% of steam energy discharged to cooling tower).

  3. The above are at full load , original equipment. As the unit ages, the heat rate gets worse. Some upgrades are possible ,especially better LP turbine blades.

  4. Newer plants will have better efficiencies, but they have to be built first.

  5. The cooling tower does not discharge directly to a river- the small blowdown may need to be treated first before discharge, so there is no relevance to the cooling tower DT- but for estimating purposes, the circulated water may have a 20F DT. (davefitz)

For your information guesses based on 400MWe lignite fired unit:

  1. Cooling Tower Water Consumption
    CW flow 10000kg/s
    Cooling range 12C
    Approach temp 8C
    DBT 30C, WBT 23.87C
    Low tech (4 concentrations, 0% reclaim of purge) 690tonnes/h
    High tech (8 concentrations, 60% reclaim) 640 tonnes/hour

  2. Boiler and demin
    Boiler steam flow 316kg/h
    Boiler blowdown 3% of steam flow
    Demin plant 34 tonnes/h with loss of 15%
    Low tech 0% blowdown recovery 53 tonnes/h
    High tech 50% blowdown recovery 35 tonnes/h

  3. Ash handling
    13kg/s ash
    20% bottom ash, 80% fly ash
    Bottom ash water 8kg/kg ash
    Fly ash water 3kg/kg ash
    Low tech (60% reclaim of ash water) 75 tonne/h
    High tech (100% dry ash removal) 0 tonnes/h

FGD loss 0.15 tonne/h per MW output
Domestic loss 0.01 tonne/h per person with 126 people
Service water 5 tonnes/h
Low/High tech 66 tonne/h

No information on nuclear (athomas236)

There are many plants, both coal and Nuke that run with cooling towers and zero discharge of water. They recycle and reuse the water until all that is left is solid waste. They have to make up what is lost to evaporation in the cooling towers, but that is it. There is a cooling tower institute that has information on typical water loss rates for various sizes/usage.

In plants that use once-through flow to cool the condensers have large numbers. Typical temperature rise is between 12F and 30F. Flow rates x temp rise will be based on plant capacity.
For example 1,000MW nuke plant is running 33,000kg/sec at 16C temp rise.
Or a 325MW coal fired plant is running 4,800 kg/sec at a 14C temp rise.
The range between plants is very large. It depends on a lot of factors.(EdStainless)

Murphy’s Law hits a turbine upgrade;
New Brunswick

‘Pain all around’ from turbine fall into harbour: NB Power CEO

CBC News · Posted: Oct 20, 2008 9:39 AM AT | Last Updated: October 20, 2008

The two turbines that plummeted to the bottom of Saint John Harbour last week are damaged and won’t be ready for when the Point Lepreau nuclear reactor comes online next year, said NB Power’s chief executive officer.

A team of engineers, divers and two cranes lifted the second of the two Siemens-manufactured 107-tonne turbines on Sunday after it had spent five days under 10 metres of water on the harbour floor.

David Hay, the president and chief executive officer of NB Power, said the damage inflicted on the rotors as a result of the plunge is easy to see, but the full extent of that damage, and that caused by exposure to salt water, isn’t known.


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