Types of Turbine Heat Rate

Turbine heat rate can be divided as two types:

Gross Turbine Heat Rate

Gross turbine heat rate can be obtained by dividing the heat energy or enthalpy added in steam boiler among the outlet of steam and the inlet of feedwater by the output of generator in kW (kilowatt). The gross turbine heat rate can be stated in kJ/kWh or Btu/kWh. Reheater can be utilized to add heat energy in the steam turbine and generate reheat cycle. The table 1 below is example of gross turbine heat rate values.

Net Turbine Heat Rate

The net turbine heat rate can be established similar to gross turbine heat rate, with the exception of the input power of boiler feed pump is taken away from the output power of generator previous to dividing towards the enthalpy (heat energy) which is added in steam boiler.

Turbine heat rate with regard to regenerative turbine is understood to be the heat energy usage of the turbine with regards to “enthalpy in steam” provided by the steam boiler, subtract the “enthalpy in the feedwater” when warmed up by the extraction in turbine, divided by the power output on the generator.

This description involves electrical and mechanical failure / losses of turbine and generator process, however excludes boiler ineffectiveness and pumping deficits. The turbine heat rate is helpful for doing economical evaluations of different turbine designs and also engineering.

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