What should the inlet pressure of the turbine condensate pump be?
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The pressure inside the turbine condenser is negative, i.e., it is a vacuum. There is a liquid level in the heat well; so, what should be the inlet pressure of the condensate pump? Is it positive pressure or negative pressure?
It is approximately the gravitational pressure difference from the hot well level to the inlet of the condensate pump, and it is a positive pressure.
What the poster is asking is: if there is a pressure gauge in this area, should it indicate positive pressure or negative pressure? ? Firstly, whether it is positive pressure or negative pressure here doesn’t make much of a difference, as an adequate liquid level in front of the pump ensures proper fluid intake. The pump is also located within this sealed vacuum system, so it’s sufficient to ensure that the relative pressure is normal! Firstly, if a pressure gauge is used for measurement, the static hydraulic pressure at the pump inlet can be calculated using a formula to be around 30 KPA. Adding the vacuum level at the liquid surface (which is usually above -60), the resulting value is -30 KPA; thus, it is indeed in a negative pressure state under normal conditions!
I agree with the admin on the 3rd floor; the inlet of the condensate pump is indeed under negative pressure, (*^__^*) hehe… I’ve tested it myself.
I feel that whether it’s positive pressure or negative pressure, it doesn’t make much difference for the entire system. But if you really need to do the calculations, you can use the formula P=ρgh. The density of water decreases as temperature rises; you can look up the corresponding density for the condensate temperature in your facility, calculate the static pressure, and then add the vacuum level of your facility’s vacuum system to get the final value
It should be that the exhaust pressure of the turbine minus the static pressure due to the level of the hot well fluid equals the inlet pressure of the condensate pump! If the static pressure at the pump inlet due to the hot well fluid level is 50 kPa (5 meters), and the exhaust pressure of the turbine is -90 kPa, then the pump inlet pressure must be -40 kPa! !
There are vacuum balance valves at the inlet and outlet of the condensate pump; the entire system is part of the turbine’s vacuum system. As long as the vacuum balance system is not disrupted, the relative pressure can reach the inlet pressure of the pump.