Which of the following are applied (used) ways of compounding steam turbines?

1. Pressure compounding

2. Temperature compounding

3. Velocity compoundingThis question was previously asked in

ESE Mechanical 2020 Official Paper

Option 4 : 1 and 3 only

CT 3: Building Materials

2962

10 Questions
20 Marks
12 Mins

__Concept:__

There are three types of compoundings used in steam turbines which are:

(1) Pressure compounding

(2) Velocity compounding

(3) Pressure-Velocity compounding

Compounding is done to decrease the high rotational speed of simple impulse turbines to bring it down to the practical limit required for electricity generation. There are two ways of compounding i.e. pressure compounding and velocity compounding.

In pressure compounded impulse turbine (or Rateau turbine), the total pressure drop is planned for more than one stage and each stage consists of a set of nozzles and moving blades, as the enthalpy in each stage is decreased, it decreases the rotational speed.

Whereas in velocity compounded impulse turbine (or Curtis turbine), the total velocity drop is arranged in more than one stage and each stage consists of a set of fixed and moving blades. There is a single nozzle in which total pressure drop takes place and the high velocity obtained is converted into work in more than one stage.

How the pressure and velocity of steams drop for a pressure compounded and a velocity compounded impulse turbine can be seen from the following figure.