Why does a control valve hunt?

Control valve hunting is a condition when the valve closes and opens at an uncontrolled rate. It denotes that the control valve is unable to find the correct position in order to maintain the set process conditions. In a closed loop this causes the process variable to move around its set point.

What are the factors that affect the performance of steam turbines?

The significant operating parameters of a steam turbine are the steam inlet temperature and pressure, and the exhaust back pressure or the vacuum drawn for condensing steam turbines. The variations in these parameters affect steam consumption and efficiency.

What is hunting in control systems?

In control system: Basic principles. overcorrect itself, a phenomenon called hunting may occur in which the system first overcorrects itself in one direction and then overcorrects itself in the opposite direction. Because hunting is undesirable, measures are usually taken to correct it.

What is bleeding of steam turbine?

Bleed steam is steam tapping taken from different stages of turbine according to the required temperature and pressure. They are many in numbers, such as bleed steam is used for high pressure and low pressure feedwater water heating, gland steam seals.

What are main components of steam turbine?

rotor
The main parts of a steam turbine are (1) the rotor that carries the blading to convert the thermal energy of the steam into the rotary motion of the shaft, (2) the casing, inside of which the rotor turns, that serves as a pressure vessel for containing the steam (it also accommodates fixed nozzle passages or stator …

What is actuator hunting?

When control loops are not properly tuned, actuators may fail prematurely, and the system can provide poor temperature or flow control. Space temperature changes occur slowly in a stable process.

What causes hunting oscillation?

A classical hunting oscillation is a swaying motion of a railway vehicle (often called truck hunting or bogie hunting) caused by the coning action on which the directional stability of an adhesion railway depends. It arises from the interaction of adhesion forces and inertial forces.