Author: haroonkhan

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,…

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…

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.…

The velocity diagram for 50% reaction turbine is shown in Figure 5.15. Since, Also, β1 ≠ β2, the blades are unsymmetrical and ΔVa = 0. There is no axial thrust in 50% reaction turbine. However, there will be considerable tangential thrust produced due to the pressure difference across the blades in each rotor disc since there is pressure…

It is ratio of cumulative heat drops and isentropic heat drops in multistage turbine. The line which joins the actual points at the end of expansion in each stage is known as condition line (Figure 5.14). Figure 5.14 Enthalpy Drops in Multistage Turbine

If steam expands both in nozzle as well as in blades of turbine, i.e., pressure at inlet of the turbine is more than that of outlet, it is known as impulse-reaction turbine. In this case, expansion of steam in nozzle creates impulse on blades and reaction due to minor expansion of steam during passing through…

It is combination of pressure compounding and velocity compounding as shown in Figure 5.9a. There are two rotors and only two rows of moving blades are attached on each rotor because two row wheels are more efficient than three row wheels. The steam on passing through each row of moving blades reduces its velocity, but pressure remains…

In this compounding, whole pressure drop takes place in nozzle (only one row) and remains constant in fixed and moving blades. Velocity of steam remains constant in fixed blades and decreases in moving blades. Figure 5.12a shows a two rows Curtis or velocity staging having two rows of moving blades and one row of fixed blade…

Pressure compounding is splitting of whole pressure drop of steam from steam chest pressure to condenser pressure into series of small pressure drops across several stages of impulse turbine. The whole pressure drops occur in series of nozzles and there is no pressure drop in fixed blades as shown in Figure 5.11. The kinetic energy of steam…