Why is the thermal efficiency of condensing steam power plants so low?
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Why is the thermal efficiency of condensing steam power plants so low?
A condensing steam turbine is one in which the turbine’s exhaust steam is directly discharged into a condenser. A back-pressure turbine is one in which the turbine’s exhaust steam is used to supply heat to end-users under conditions of pressure higher than atmospheric pressure. When the exhaust steam is used as feed steam for other medium- or low-pressure turbines, it is referred to as a forward-pressure turbine. The calculation methods for efficiency differ slightly between units used for heating and those used purely for power generation, with heating units having a higher thermal efficiency.
Condensing steam turbines incur cooling loss, with 60% of the heat being released into the atmosphere.
In a condensing steam turbine, it must be steam that is discharged into the condenser; the latent heat of vaporization cannot be utilized, which results in low thermal efficiency.
Condensing thermal power plant: Boiler thermal efficiency 96%； The turbine efficiency is around 92%. The efficiency of the steam Rankine cycle is around 40% (the overall thermal efficiency of the pipes and other cycle components). The overall efficiency is only around 35%. Adding the losses from coal powder combustion and those inherent in the generator connected to the turbine, the overall power generation efficiency of the power plant is only about 1/3. Although there has been an improvement, it is still only around 35%. In terms of quantity, energy is primarily lost in the condenser, while in terms of quality, it is primarily lost on the boiler side. In condensing steam power plants, all the steam discharged by the turbines is condensed into water, resulting in significant energy loss; therefore, the energy consumption is very low