how to compute for steam output to equivalent electricity?
If the total steam output of a boiler is fed to a steam turbine, what is the equivalent electricity produced? What are factors included in the calculations?
Fuel is used to boil the water. The pressure and temperature of the steam determines how much energy is in it. The steam goes to the turbine, giving up much of its energy to make mechanical energy, which generates electricity. The waste steam goes to a cooler that cools it back down to water. The water is then pumped back into the boiler.
Max efficiencies are somewhere around 38%. Higher pressure and temperatures for the steam, lower cooling temperature, more efficient boiler/turbine/pump improve efficiency.
The calculations use steam tables, which are lists of the properties of steam at different pressures and temperatures. Specifically, thermodynamic properties include enthalpy, entropy, internal energy.
In simple terms, take the enthalpy of the steam into the turbine & enthalpy out and subtract them. The BTU's per pound is the energy the turbine extracted. Typically, the turbine will be rated for particular pressures in & out (with a handy chart to help figure), so you'll know it's at 10 lb steam per kW out or whatever.
Efficiency is the difference between what would be produced with entropy staying the same & what's actually produced - usually, the temp leaving is usually lots hotter.
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Fuel is used to boil the water. The pressure and temperature of the steam determines how much energy is in it. The steam goes to the turbine, giving up much of its energy to make mechanical energy, which generates electricity. The waste steam goes to a cooler that cools it back down to water. The water is then pumped back into the boiler.
Max efficiencies are somewhere around 38%. Higher pressure and temperatures for the steam, lower cooling temperature, more efficient boiler/turbine/pump improve efficiency.
The calculations use steam tables, which are lists of the properties of steam at different pressures and temperatures. Specifically, thermodynamic properties include enthalpy, entropy, internal energy.
In simple terms, take the enthalpy of the steam into the turbine & enthalpy out and subtract them. The BTU's per pound is the energy the turbine extracted. Typically, the turbine will be rated for particular pressures in & out (with a handy chart to help figure), so you'll know it's at 10 lb steam per kW out or whatever.
Efficiency is the difference between what would be produced with entropy staying the same & what's actually produced - usually, the temp leaving is usually lots hotter.