Calculation of turbine efficiency and Rankine cycle efficiency for the given plant.

 

Steam Turbine efficiency

 

Efficiency= Energy output/ Energy input

 

Heat input = Steam inlet flow in TPH * Enthalpy of inlet steam (Kca/Kg)

                = 168*811

                = 136248 Kcal

 

Heat out put  = Power in MW* Heat equivalent of Power

                =30*860

                =25,800 Kcal

 

 

Efficiency of Steam Turbine =   Heat output/ Heat input

                                             = 25,800/136248

                                              = 18.93%

 

 

 

Rankine cycle efficiency for given plant:

 

W1=30 MW

 

W2= 1MW (assumed)

 

Q1= Heat input to a Boiler

     =m*(h1-h4)

     =336*(811-150)   (where 336 is total steam generation in Boilers)                                                     .    =222096

     =246773 Kcal(assuming Boiler efficiency of 90%) .

 

In a power plant that produces both Steam and power, we must give credit to Steam export also

 

Useful output as steam export= Steam export flow*Heat value (Kcal/Kg) 

                                            =150* 760

                                            =114000 Kcal                                                      

 

Efficiency of cycle is = ((W1-W2)+( Heat value of export steam)) /Q1

                                 =((60-2)*860)+114000)/ (246773) 

                                  =66.40%