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phillipwon
Associate

Join Date: Nov 2011
Posts: 42

Steam Turbine Power Output vs. Condenser Vaccum

09/27/2012 6:06 AM

Suppose that there is water cooled condenser in ST. TTD is 5 C, which is ST exhaust temperature is 47 C (0.01062 bar.ata) and cooling return water temperature to the cooling tower is 42 C. (cooling supply water temperature to the condenser is 32 C., anyway) At this design condition, if we just make more vacuum in the condenser using more vaccum pump, can we decrease ST exhaust temperature and TTD?
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Joshi
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Join Date: Oct 2007
Location: India
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#1

Re: Steam Turbine power output vs condenser vacuum

09/27/2012 6:26 AM

Could you please repost in this thread, with all acronyms in its full form?
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Joshi
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Join Date: Oct 2007
Location: India
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#2
In reply to #1

Re: Steam Turbine power output vs condenser vacuum

09/27/2012 6:39 AM

Please follow & read these:

Improvement Power Plant Efficiency with Condenser Pressure - IJMSE

Improve Steam Turbine Efficiency Understand the factors ... - IFFCO

Steam Turbines and Condensers - IAGT Committee
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PWSlack
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United Kingdom - Member - Indeterminate Engineering Fields - Control Engineering - New Member

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Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on.
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#3

Re: Steam Turbine power output vs condenser vaccum

09/27/2012 7:06 AM

The without any refrigeration unit in circuit, the vacuum in the condenser is a function of the local wet-bulb air temperature, for that is where the 'coolth' is coming from. The lower this temperature, the stronger the vacuum and the higher the power output from the turbine.

It is not possible to increase the vacuum beyond that indicated by the boiling pressure of water at the cooling fluid temperature. For values, see published Steam Tables.

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bigg
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Join Date: Jun 2010
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#4

Re: Steam Turbine Power Output vs. Condenser Vaccum

09/27/2012 10:12 AM

First, I think you meant 0.1062 bar atm (= 3.13 " Hg, 47 degC saturation temp.); 0.01062 bar gives saturation temperature of 45 degF, 7 degC.

The vacuum pump's purpose is to remove non-condensables (air) from the condenser. If your condenser's pressure corresponds to the condensing temperature (indicating no non-condensables present), adding more vacuum pumps will not improve the vacuum. If your condenser pressure is 0.1062 bar with 42 degC return water, I'd say that's pretty good. I would try to lower the return water temperature by improving condenser water flow and checking cooling tower performance. What is your wet bulb temperature?
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bigg
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Join Date: Jun 2010
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#5
In reply to #4

Re: Steam Turbine Power Output vs. Condenser Vaccum

09/27/2012 6:24 PM

By the way, what is your turbine's design exhaust pressure?
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maihahue
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Join Date: Sep 2012
Posts: 3
#6

Re: Steam Turbine Power Output vs. Condenser Vaccum

09/28/2012 4:31 AM

I agree with Bigg.

By the way can you inform me what is the turbine output rate in this condition? 100% or less then it?
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dhayanandhan
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Engineering Fields - Mechanical Engineering - New Member

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#7

Re: Steam Turbine Power Output vs. Condenser Vaccum

09/28/2012 1:10 PM

Dear Mr. philipwon,

The Vaccuumm in the condenser is governed by 2 Factors.

1. The Total and perfect condensing of the Steam, by removing the Latent Heat of the Steam entering the condenser, by optimising the Rate of Circulating Water in the condenser.

2. By removal of the NON-CONDENSIBLE AIR in the condenser.

More vaccuum creation- needs additional energy to be spent- and perhaps it may not be worth as we have to strike a balance for optimum result. Clear HEAT BALANCE will indicate the correct picture.

DHAYANANDHAN.S
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phillipwon
Associate

Join Date: Nov 2011
Posts: 42
#8

Re: Steam Turbine Power Output vs. Condenser Vaccum

09/30/2012 7:17 AM

Thanks everyone who answer my question. It really helps understand logic. Thanks!
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bigg (2); dhayanandhan (1); Joshi (2); maihahue (1); phillipwon (1); PWSlack (1)

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