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Pasindu Perera
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Join Date: Jul 2013
Posts: 3

Pressure Need to Maintain in Low Loads

07/07/2013 12:43 PM

My power plant is a 300MW power plant which operates in 16.7 MPa maximum pressure. How to find the correct pressure for low loads of the plant. Example: at 180 MW what is the most effective pressure.
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lyn
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Join Date: Oct 2008
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#1

Re: Pressure need to maintain in low loads

07/07/2013 1:23 PM

What does the operator's manual say?

What does the the factory rep say?

What does the the local power plant tech say?

What does your maintenance tech say?

What does the manufacturer's web site say?

What type of equipment is it?
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Pasindu Perera
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Join Date: Jul 2013
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#4
In reply to #1

Re: Pressure need to maintain in low loads

07/07/2013 1:33 PM

I cannot find any thing related to this in operators manual. Manufacturer is from china harbin turbine factory and it is very difficult to discuss with them in English. So the boiler is water tube type boiler.
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Fredski
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#2

Re: Pressure need to maintain in low loads

07/07/2013 1:24 PM

less than 16.7mPA
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lyn
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#3
In reply to #2

Re: Pressure need to maintain in low loads

07/07/2013 1:31 PM

300mW= 16.7 mPA.

180mW= about 10mPA, as I see it.

Maybe here:

The Boiler House : International site for Spirax Sarco
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Tornado
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#5

Re: Pressure need to maintain in low loads

07/07/2013 4:05 PM

Whatever pressure maintains the frequency within the desired range.

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dhayanandhan
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#6

Re: Pressure Need to Maintain in Low Loads

07/08/2013 4:36 AM

Dear Mr.PasinduPerera,

For varying loads, the Steam Flow alone should vary and not the Pressure, temp. etc.

The Velocity of Steam over the Blades whether it is moving blade or stationary stationary , is mainly dependent on the Specific Volume, secondly to the Flow Rate.

For low Pressure, the Sp.Volume of Steam will go up (as can be seen from the Steam Tables) and increase in Velocity beyond a limit will lead to problem in the Turbine.

DHAYANANDHAN.S
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Lalit Shukla
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#7

Re: Pressure Need to Maintain in Low Loads

07/08/2013 8:35 AM

If you run the turbine below the temp & pressure value chest pressure of turbine rise & also axial movement of turbine rotor increase which will damage your turbine rotor also.

So be careful doing anything .
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James Stewart
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#8

Re: Pressure Need to Maintain in Low Loads

07/08/2013 6:02 PM

1. Never exceed the OEM maximum pressure rating (your steam safety valves should lift just prior to this).

2. One primary concern relative to pressure of operation is the limitation imposed by silica in the boiler brine (if this boiler has a pressure steam drum). If here you have a "once-thru" boiler where all feed-water is vaporized immediately, then the requirements match those for the maximum allowable silica in steam which for any rotating equipment I know of is approximately 0.020 mg/L (20 ppb). This would be considered by many to fairly "dirty" steam, but still should not leave silica deposits on turbine blading.

3. Another primary concern is overall heat rate per MW at various pressures. You may need to analyze the heat balances to arrive at this.

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Users who posted comments:

dhayanandhan (1); Fredski (1); James Stewart (1); Lalit Shukla (1); lyn (2); Pasindu Perera (1); Tornado (1)

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