Category: Steam Engine, Steam And Gas Turbines

Intercooling is added to reduce the compressor work. If multistage compressor is used, the air is cooled to initial temperature between each stage. Reheater is used to increase the temperature to initial inlet temperature between each expansion in turbines. Thus, intercooler and reheater are used to increase the work output of turbines. The flow diagram… Continue reading Gas Turbine Cycle with Reheating and Intercooling

Regenerator is a heat exchanger which is used to exchange the waste heat of gases exhausted from turbine to air after compression but before combustion as shown in Figure 5.25. Due to this fuel economy, the efficiency of plant increases. Figure 5.25 Gas Turbine with Regenerator It is theoretically possible to raise the temperature of the compressed air… Continue reading Gas Turbine Cycle with Regenerator

In the T–s diagram (Figure 5.22), Figure 5.22 Actual Brayton Cycle For maximum work done, Wnet should be differentiated with respect to c and equating to zero. Example 5.5: In a gas turbine plant, air is compressed from 1 bar and 15°C through a pressure ratio 6:1. It is then heated to 600°C in a combustion chamber and expanded back to atmospheric pressure… Continue reading Optimum Pressure Ratio for Maximum Specific Output

The actual turbine cycle differs from the theoretical cycle in the following manner. A T–s diagram for an actual Brayton cycle is shown in Figure 5.21. Figure 5.21 Actual Brayton Cycle 1 – 2 Isentropic compression 1 –2′ Actual compression 3 – 4 Isentropic expansion 3 – 4′ Actual expansion The compressor efficiency, where WT = Work done by turbine             WC =… Continue reading Actual Brayton Cycle

The air standard Brayton cycle or Joule cycle is most ideal thermodynamic cycle for a simple gas turbine plant. Its working is shown in Figure 5.19. Atmospheric air is compressed from pressure P1 to a high pressure P2 in the compressor and delivered to the combustion chamber where fuel is injected and burnt. The combustion process occurs nearly at constant pressure.… Continue reading Joule or Brayton Cycle

Gas turbines are used for the following purposes:

Gas turbines can be classified on the basis of thermodynamic cycles used and the path of working fluid. On the basis of thermodynamic cycle, there are two types of gas turbines: On the basis of path of the working fluid, gas turbine can be classified as

Governing of steam turbines is to control the speed of turbines irrespective of load. Following are the methods of governing: In throttle governing system, pressure of steam entering the turbine is reduced at part loads. It is used in only small turbines due to available heat loss in irreversible throttling process. In nozzle governing system,… Continue reading Governing of Steam Turbines

There may be two types of losses—internal loss and external loss. Internal loss includes all the losses the flow of steam inside the turbine, such as losses in regulating valves, nozzle friction loss, blade friction losses, disc friction losses, partial admission losses, land leakage losses, residual velocity losses, and carry over losses, whereas external loss… Continue reading Losses in Steam Turbines

There are some basic differences between impulse and reaction turbines as mentioned in Table 5.1.   Table 5.1 Differences Between Impulse and Reaction Turbines Impulse Turbines Reaction Turbines Pressure drops occur only in nozzles.It has constant blade channel area.It has profile type blades.It can be used for small power development.It has lower efficiency due to high losses.… Continue reading Differences Between Impulse and Reaction Turbines