2 replies to this topic

[Naeema]

Hi

I would like to know if there is a formula to calculate the cooling water required for a back pressure turbine. The plant is currently using 3 generators each producing 7MW. they would like to use them to produce the maximum of 12 MW each. I need to calculate the amount of extra cooling water that will be required

[jpm.chem]

Hi

I would like to know if there is a formula to calculate the cooling water required for a back pressure turbine. The plant is currently using 3 generators each producing 7MW. they would like to use them to produce the maximum of 12 MW each. I need to calculate the amount of extra cooling water that will be required

Hi Naeema,
Its a quite interesting topic.. First let me clarify ma doubts.. Whether they are using a back pressure turbine? Bcos if it is only a BP Turbine normally they ll be using the letdown steam as a process steam( either MP or LP Steam depending upon the requirement) and there is no requirement for cooling water.. If it is a Condensing type or an Extraction cum condensing type you can worry about the cooling water requirement.. Hope am not wrong..
So here comes the method:
1. Calculate the steam requirement for the power output.
2. Using the steam flowrate calculate the Heat duty. (Q = m*lamda)
3. Then for the required duty calculate the cooling water required. (Q= m*Cp* Dt)

Edited by jpm.chem, 14 August 2011 - 06:50 AM.

[pawan]

Rightly mentioned by jpm, Naeema it seems that you first need to understand exactly what type of process you are using in your turbine.

Backpressure - generally means only enthalpy / energy extraction from high pressure steam & outlet is low pressure steam. There is no condensation. Therefore, no cooling water required.

Condensing / Exhaust turbines - means whole steam is condensed at the outlet generally under vacuum. This requires maximum amount of cooling water.

Extraction cum condensing - Its a combination of both systems explained above i.e. some part is coming out as low pressure steam & remaining is condensed.

In all the cases, same principal applies of heat removal for condensation of steam should be equal to the energy gained by cooling water flow rate.