thePetroStreet

How to evaluate the Hp and efficiency of a condensing turbine if this is a driver of a compressor?

There are several methods to do so
One is to calculate heat load rejected to cooling water + the enthalpy of condensate leaving condenser. Heat load of the condenser can be calculated by applying simple heat balance across cooling water side & enthalpy of the condensate (leaving Condenser) can be calculated at outlet temperature and pressure of steam condensate and
H2 (at turbine outlet) = (change in enthalpy of Cooling water) + Enthalpy of condensate at condenser outlet.
By comparison of (H2-H1) at operating conditions and in ideal conditions one can calculate hp as well as efficiency of condensing steam turbine.
Second could be to install a steam quality meter at the downstream of your steam turbine and directly evaluate the performance of your turbine by calculating change in enthalpy across it.

Thanks allot for the detailed reply......

Looking forward for your usual cooperation.

For condensing steam turbines, companies always refer to use torque meters, for accurate measure of horse power delivered. There meter are installed with the coupling in-between the turbine and compressor / any other driven equipment.
But if you are calculating horse power for comparison or for reference (where you should be precise rather than being accurate), you can assume a specific percentage of turbine hp as losses, as a fix. By doing that you can evaluate compressor horse power, and then by adding that fixed percentage of mechanical losses, you can be come up with turbine hp. By knowing other parameters along hp, you can easily calculate condensing turbine efficiency.
This method will give you precise measure of any efficiency drop, and off-course easy to do. But for both accurate and precise measure, you need to invest some money for installing torque meter.
hope you get your answer.