Boiler Water Level Control System

A three element boiler water level control system is shown in figure above.

Boiler water level control system.

A steam engine moving some sort of machine heating producing vacuums through the use of steam ejectors and augmenting chemical. However with single element proportional control the water level must fall for the feedwater control valve to open. The controller then generates an output signal telling the control valve to either introduce more or less water into the boiler to maintain the steam drum water level at setpoint. Since in a balanced situation steam flow must equal feed flow these two signals are compared in a differential relay.

This post explains the simple closed loop function with the example of boiler water level control system. This posts helpful to understand the basic principle of a control loop and its components. Boiler drum level control systems drum level control systems are used extensively throughout the process industries and the utilities to control the level of boiling water contained in boiler drums on process plant and help provide a constant supply of steam. This is because of the fact that as the steam demand increases the pressure in the boiler drops causing the water level to rise.

The control of water level is a major function in this process and it is achieved through a water steam interface established in a cylindrical vessel called the drum which is usually lying on its side and located near the top of the boiler. Common uses for steam in industry include doing mechanical work e g. Controlling the boiler drum level is complicated as the water level in a steam drum is actually a fairly unstable mixture of water and steam bubbles that shrinks and swells as the pressure changes. Fig boiler water level control a three element control system is shown in figure.

If the level is too high flooding of steam purification equipment can occur. The standard single element boiler water level control system with proportional control gives excellent control on the majority of boiler installations. The measured variables or elements are steam flow drum flow and feed water flow. Measured variables or elements are steam flow drum level and feed water flow.

Steam boilers are very common in industry principally because steam power is so useful.