Question

A turbine with one extraction for regenerative feed water heating receives steam with

an enthalpy of 3373 kJ/kg and discharges it with an exhaust enthalpy of 2326 kJ/kg.

The ideal regenerative feed water heater receives 11,338 kg/h of extracted steam at

345kPa (whose h=2745kJ/kg). The feedwater (condensate from the condenser)

enters the heater with an enthalpy of 140kJ/kg and departs saturated at 345kPa

(hf=582kJ/kg). Calculate the turbine output in kW.

Answer 1

$\dot{x} =11338 kg/h=3.15kg/s$

$\dot{m} h_s=\dot{x} h_s +(\dot{m} -x)h_4$

$\dot{m} *582=3.15*2745 +(\dot{m} -3.15)140 \implies \dot{m}=18.565 kg/s$

Turbine output $\dot{m}(h_1-h_2)+(\dot{m}-\dot{x})(h_2-h_3)$

$18.565(3373-2745)+(18.565-3.15)(2745-2326)=18117.7 kW$