Turbine condenser cooling water control

[whycurious]

We have steam turbines for power generation. For some of the process users, we need warm water for cooling. One option would be to use the steam turbine condenser outlet. This would need some temperature and flow control at cooling water outlet of condensers. The flow required for process users is 20 to 30 % of the total water flow from condenser. The water flow is a once through system.

Has someone used this type of control schemes or any other scheme, where control valve is used to regulate the cooling water flow to obtain water outlet in desired temperature range. There is some concern that any control device on water side will affect the dynamics of process and thus the vacuum in the condensers and in turn power generation.

 

[rmw]

The concern is well placed. If you throttle the water flow so as to raise the outlet temperature to obtain water for process purposes, the back pressure in the condenser will rise and the power generation turbines will be less efficient or will have less capacity.

The back pressure will rise for a variety of reasons having to do with the approach temperatures, the tube side velocity reduction due to throttling, and overall reduced water flow.

I haven't seen many power turbines that had a lot of excess condenser capacity. Usually the opposite is true.

I suggest that if you really need this heated water in your process, then you take the outflow of the condenser at whatever temperature it coms out, and take that to a heater using steam from another source (hopefully some form of waste steam) and heat the water to the temperature to what it needs to be. If your turbines are designed for it, you might be able to extract some steam for the heaters.

rmw