Steam Turbine Calculator

U.S. Dept. of Energy | Energy Efficiency & Renewable Energy

 

Click here to access the CALCULATOR.

U.S. Department of Energy Steam Turbine Calculator How-To

This calculator can be used to produce rough approximations of power and/or steam flow given a set of conditions.  Please note that this is a generic tool developed by the US Department of Energy, and that more precise results for Elliott steam turbine generators with controlled and/or uncontrolled extractions can be provided by contacting Elliott. 

There are 2 common methods of use for the U.S. Department of Energy Steam Turbine Calculator:

  1. Calculate Steam Turbine (Generator) Power, given:
    1. Inlet Pressure
    2. Inlet Temperature
    3. Steam Flow
    4. Exhaust Pressure

*This is the most typical method when calculating ST output. Please see the section below titled “1. Calculating Steam Turbine Power Given Steam Conditions and Flow” for directions.

  1. Calculate Steam Flow, given:
    1. Inlet Pressure
    2. Inlet Temperature
    3. Exhaust Pressure
    4. Desired Power (kWe)

* Please see the section below titled2. Calculating Steam Flow Given Steam Conditions and Power for directions.

Instructions

Please note:  The U.S. DOE steam turbine calculator uses units of PSIG and °F. Though it sometimes shows °C for temperature, it will calculate as if your input was in °F.

1. Calculating Steam Turbine Power Given Steam Conditions and Flow

  1. Set “Solve For” drop-down to Outlet Properties
  2. For Inlet Steam section:
    1. Enter Inlet Pressure (PSIG)
    2. Enter Inlet Temperature (°F)
  3. For Turbine Properties section:
    1. “Selected Turbine Property” drop-down to Mass Flow
    2. Enter Steam Mass Flow (klb/hr [e.g. 36,000 lbm/hr = 36.0 klbm/hr])
    3. Enter assumed isentropic efficiency (see Table 1 below)
    4. Enter assumed generator efficiency of 93% (takes gearbox losses and generator losses into account)
  4. For Outlet Steam section:
    1. Enter desired Exhaust Pressure (PSIG)
      1. If condensing exhaust condition, pressure units must be converted to PSIG (See Table 1 for basic conversions)

2. Calculating Steam Flow Given Steam Conditions and Power

  1. Set “Solve For” drop-down to Outlet Properties
  2. For Inlet Steam section:
    1. Enter Inlet Pressure (PSIG)
    2. Enter Inlet Temperature (°F)
  3. For Turbine Properties section:
    1. “Selected Turbine Property” drop-down to Power Out
    2. Enter assumed isentropic efficiency (see Table 1 below)
    3. Enter assumed generator efficiency of 93% (takes gearbox losses and generator losses into account)
    4. Enter desired power at the generator (kWe [electrical power])
  4. For Outlet Steam section:
    1. Enter desired Exhaust Pressure (PSIG)
      1. If condensing exhaust condition, pressure units must be converted to PSIG (See Table 1 for basic conversions)​​

Table 1: Exhaust Pressure Conversion Table

inHgA PSIG
4 -12.7354
6 -11.7561
8 -10.7708

 

 

 

 

Table 2: Estimated Isentropic Efficiencies of Steam Turbines

Turbine Type Exhaust Type Average (%)
Single Stage Back Pressure 53
Single Stage Condensing 57
Multi-Stage <10 MW BackPressure 60
Multi-Stage <10 MW Condensing 67
Multi-Stage > 10 MW Back Pressure 75
Multi-Stage > 10 MW Condensing 80

 

 

 

 

 

 

Note: Isentropic efficiencies of Steam Turbines can range from 20-90%. The efficiencies in Table 1 are simplified values for the purpose of estimating industrial type Steam Turbine Generators. For firm performance values please contact the Power Generation Team at Elliott Group.