Pressure correction for intermediate-pressure steam turbine efficiency

For the power generation industry equipment performance is a major concern. The information obtained is not only used to ascertain the current condition of any particular piece of equipment, it is also used to forecast equipment maintenance and reliability. The accuracy of this information is vital. Small fluctuations in turbine efficiency can have considerable financial implications over the lifespan of the turbine; therefore, accurately monitoring efficiency is financially prudent.;Consumers Energy was presented with a unique problem concerning the efficiency associated with the intermediate-pressure turbine section of a General Electric 160 MW reheat steam turbine. The intermediate-pressure turbine section generates approximately 45 MW of the total 160 MW generated. The enthalpy-drop method for calculating efficiency is very sensitive to fluctuation in exhaust steam pressure. For the particular turbine under consideration the sensitivity to pressure fluctuation is exasperated by the physical geometry of the exhaust duct. A pressure correction algorithm was developed using empirical data in conjunction with the fundamental conservation laws.