Fossil and Nuclear power plant heat rejection...
Fossil and Nuclear power plant heat rejection...
(OP)
Hello,
For a fossil power plant and a nuclear power plant with the same capacity of power generation(i.e 700 MW)which plant would reject more heat to atmosphere and could you please say why?
For a fossil power plant and a nuclear power plant with the same capacity of power generation(i.e 700 MW)which plant would reject more heat to atmosphere and could you please say why?





RE: Fossil and Nuclear power plant heat rejection...
I don't think the nuclear plants are using as high superheat and reheat temperatures as the best combustion boilers can, but on the other hand, the nuclear plants aren't throwing heat out a chimney. It's likely a wash, but I'm open to seeing better information from others.
RE: Fossil and Nuclear power plant heat rejection...
Diablo Canyon appears to be similar: http
There are presumably others that are designed to dump their heat load into the atmosphere, like: http://www.nrc.gov/info-finder/reactor/susq1.html
TTFN
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RE: Fossil and Nuclear power plant heat rejection...
TTFN
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RE: Fossil and Nuclear power plant heat rejection...
If it's the latter, the question can't be answered, because there are examples of power plants regardless of power source that are cooled *directly* by varying combinations of seawater, lakewater, or atmosphere ... All that heat is going *somewhere*, though. One thing that can be stated is that the fossil fuel plants always have a chimney, and the nuclear plants don't (at least, not for the main power source).
RE: Fossil and Nuclear power plant heat rejection...
The question of heat to the environment is indeterminent. You would have to do a heat balance on each particulare plant to compare the benefits of superheat vs. not having combustion ineffeciencies vs. steam generator fouling. With two plants both operating within design, I would expect that the pluses and minuses would cancel and two 700 MW plants would each dump about the same amount of waste heat to the environment.
David
RE: Fossil and Nuclear power plant heat rejection...
In a PWR, the steam generation is done by a pressurized water system that is heated by the reactor. Thus, a potentially sizable portion of the reactor heat might be lost in the reactor, as well as in the primary pressurized water loop.
TTFN
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RE: Fossil and Nuclear power plant heat rejection...
Let me clarify my means: I would like compare the heat rejection of a CANDU nuclear plant(700 MW) with a coal-fired fossil plant(700MW) both via the main condenser to a cooling tower, just learn me which one has overally more heat rejection than the otherone.
RE: Fossil and Nuclear power plant heat rejection...
RE: Fossil and Nuclear power plant heat rejection...
TTFN
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RE: Fossil and Nuclear power plant heat rejection...
but using a SWAG I would "think" the conditions at the condensor indeed would be the same. However given the intial conditions are so much less for the Nuke, the steam flow to produce the same MW as the fossil would be more those more more BTUs/hour into and out of the condesor.
I should have heat balance charts, but I can't find them at this time. (since I never really cared, I don't recall where they might be packed away)
RE: Fossil and Nuclear power plant heat rejection...
What the nuclear reactor does with its excess capacity would be a different question. San Onofre and Diablo Canyon are both designed around 1100 MW generators, so there's hypothetically a design that would suit a 700 MW generator, although the overall cost/benefit might be too low for 700 MW, which is yet another question.
TTFN
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RE: Fossil and Nuclear power plant heat rejection...
RE: Fossil and Nuclear power plant heat rejection...
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(2B)+(2B)' ?
RE: Fossil and Nuclear power plant heat rejection...
byrdj,
Yes, thermodynamics is a creation of the devil.
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If we learn from our mistakes I'm getting a great education!
RE: Fossil and Nuclear power plant heat rejection...
David
RE: Fossil and Nuclear power plant heat rejection...
versus a drum at 2400 psig 1050F or
a once through at 3500 psig 1050F
and with 1000F reheat
RE: Fossil and Nuclear power plant heat rejection...
I agree with "electricpete", he got answer of my question.
RE: Fossil and Nuclear power plant heat rejection...
Hence a X hundred MW nuclear plant due to the fact that it operates at lower temperatures AND pressures requires MUCH more steam flow for the same MW output than a fossil plant (assume the highest efficiencies obtainable - ultra supercritical double reheat machines) would.
The steam flow that ultimately gets to the condenser(s) dictate what the heat rejection to the environment is.
I think if you can find a copy of the book STEAM by B&W, you will find some heat balances for similalr sized fossil and nuclear plants, if memory serves. I know they have heat balances for some fossil sized units about the size you mentioned.
rmw