Page 157 - DJJ20063- Thermodynamics 1

DJJ20063- Thermodynamics 1

Specific steam consumption

Another criterion of performance in steam plant is the specific steam consumption. It

relates the power output to the steam flow necessary to produce steam. The steam flow

indicates the size of plant with its component part, and the specific steam consumption is a
means whereby the relative sizes of different plants can be compared.

The specific steam consumption is the steam flow in kg/h required to develop 1 kW,

i.e. W x (specific steam consumption, s.s.c.) = 1 x 3600 kJ/h
(where W is in kJ/kg),

3600
i.e. s.s.c. = kg/kwh
W

3600
or. s.s.c. = kg/kwh (4.24)
(h − h 2 ) − (h − h 3 )
4
1

Example 4.4

A steam power plant operates between a boiler pressure of 42 bar and a condenser

pressure of 0.035 bar. Calculate for these limits the cycle efficiency, the work ratio,

and the specific steam consumption for a Rankine cycle with dry saturated steam at

entry to the turbine.

Solution to Example 4.4

The Rankine cycle is shown in the figure below.

42bar

5 1
526.2

4 0.035 bar
299.7 3
2

s
A B
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