(48e) Assessing Efficiency of a Condensing Steam Turbine with a Torque Measuring Coupling

Assessing steam turbine efficiency once was a tedious job but the advent of electronic steam tables have made the task much more streamlined. Information from process data historians can be downloaded into spreadsheets with thermodynamic properties defined and performance assessed.

While this is typically straightforward for a back-pressure steam turbine, it is more complicated for a condensing steam turbine given the under-defined nature of the solution. Without knowing the vapour fraction of the steam exiting the turbine it’s impossible to determine the outlet enthalpy, and thus the power.

This discussion will focus on how performance can be determined in back pressure and condensing sections of steam turbines. The solution presented involves measuring steam flow, section inlet and exhaust pressures and temperatures, as well as output power A worked example is included where efficiency improvement is quantified following an overhaul.