GAS TURBINE POWER PLANT 297- There are no standby losses in the gas turbine power plant whereas in steam power plant these
losses occur because boiler is kept in operation even when the turbine is not supplying any
load. - The maintenance of the plant is easier and maintenance cost is low.
- The lubrication of the plant is easy. In this plant lubrication is needed mainly in compressor,
turbine main bearing and bearings of auxiliary equipment. - The plant does not require heavy foundations and building.
- There is great simplification of the plant over a steam plant due to the absence of boilers with
their feed water evaporator and condensing system.
9.14 Disadvantages
- Major part of the work developed in the turbine is used to derive the compressor. Therefore,
network output of the plant is low. - Since the temperature of the products of combustion becomes too high so service conditions
become complicated even at moderate pressures.
SOLVED EXAMPLES
Example 1. A gas turbine plant of 800 kW capacities takes the air at 1.01 bar and 15°C. The
pressure ratio of the cycle is 6 and maximum temperature is limited to 700°C. A regenerator of 75%
effectiveness is added in the plant to increase the overall efficiency of the plant. The pressure drop in the
combustion chamber is 0.15 bars as well as in the regenerator is also 0.15 bars. Assuming the isentropic
efficiency of the compressor 80% and of the turbine 85%, determine the plant thermal efficiency.
Neglect the mass of the fuel.
Solution. The arrangement of the components is shown in Fig. 9.30(a) and the processes are
represented on T-s diagram as shown in Fig. 9.30(b).
(^23)
2 ′
5 ′
1
5
4
P^
=^6
ba
r
2 5.^9
1 b
ar
1.^1
6 b
ar
P^ =
1.^0
1 b
ar
1
S
6 T
2
Exhaust Fuel
(^34) CC
5
GT
1
Regen.
C
(a)(b)
Fig. 9.30
The given data is
T 1 = 15 + 273 = 288 K
pl = 1.01 bar