Power Plant Engineering

GAS TURBINE POWER PLANT 305

=

3600

117.4







× 25,000 kg/hr

=

(3600 25000)

(117.4 3600)

×

×

kg/s = 212.95 kg/s

THEORETICAL QUESTIONS

1.Given the advantages and limitations of gas turbine power plant.

2.Given the application of gas turbine power plants.

3.Name the major components of a gas turbine plant.

4.Draw a simple line diagram for a simple open cycle gas turbine plant.

5.Derive an expression for the thermal efficiency.

6.Define Air-rate and work-ratio.

7.What is regeneration? Flow it improves the thermal efficiency of a simple open cycle gas

turbine plant.

8.Define “effectiveness” of regeneration.

9.How “reheating” improves the thermal efficiency of a simple open cycle gas turbine plant?

10.Discuss combined steam and gas turbine power plants.

EXERCISES

1.A simple, constant pressure gas turbine is designed for a pressure ratio of 5 to 1, and a turbine

inlet temperature of 550°C. The adiabatic efficiency of compressing is 80% and that of ex-

pansion 85%, and there is a pressure loss of 0.0343bar through the combustion chamber.

Calculate

(a) the power per kg of air per sec.

(b) the overall efficiency.

Assuming the air to enter at 15°C and 1.01 bar. Take k = 1.4 and Cn = 1.047 for both air and

combustion gases. Neglect the additional mass flow due to the fuel. [Ans. 65.47, 14.27%]

2.A gas turbine has a pressure ratio of 6/1 and a maximum cycle temperature of 600°C. The

isentropic efficiencies of the compressor and turbine are 0.82 and 0.85 respectively. Calcu-

late the power output in kilowatts of an electric generator geared to the turbine when the air

enters the compressor at 15°C at the rate of 15 kg/s.

Take: cp = 1.005 kJ/kg K and y = 1.4 for the compression process, and take cp = 1.11 kJ/kg K

and y = 1.333 for the expansion process. [Ans. 920 kW]

3.In a gas turbine plant air at 10°C and 1.01 bar is compressed through a pressure ratio of 4:1.

In a heat exchanger and combustion chamber the air is heated to 700°C while its pressure

drops 0.14 bar. After expansion through the turbine the air passes through a heat exchanger,

which cools the air through, 75% of maximum range possible, while the pressure drops 0.14