Question

In the Rankine cycle of a steam power plant the turbine entry and exit enthalpies are 2803 kJ/kg and 1800 kJ/kg, respectively. The enthalpies of water at pump entry and exit are 121 kJ/kg and 124 kJ/kg, respectively. The specific steam consumption (in kg/kWh) of the cycle is ______.

Answer 1

Concept:

Specific Steam Consumption or Steam Rate (SSC) is the mass flow rate of steam required to produce 1 kW net work output.

Specific steam consumption  \(SSC = \frac{1}{{{W_{Net}}}}\frac{{kg}}{{kJ}} = \frac{{3600}}{{{W_{Net}}}}\;kg/kWh\)

Net Work = Turbine Work - Pump Work

Calculation:

W_T = 2803 – 1800 = 1003 kJ/Kg

W_P = 124 – 121 = 3 kJ/Kg

W_net = W_T – W_P = 1003 – 3 = 1000 kJ/Kg

\(SSC = \frac{{3600}}{{{W_{net}}}} = \frac{{3600}}{{1000}} = 3.6\frac{{Kg}}{{kWh}}\)