BOILER CONTROL SYSTEMS
TYPES OF CONTROLS:
Control systems may be pneumatic, analog, digital, or a
combination of the three.The present industry standard is for a
distributed control system (DCS), a programmable logic controller (PLC), or a direct
digital controller (DDC). These work based on the information gathered from sensors.

CONTROL SELECTION:
-Microprocessor digital type of controls (e.g. PLC, DDC, or DCS) are used where a large number of control loops are involved.
-Pneumatic control devices should be used in hazardous areas
-Analog logic devices are outdated.

Boiler level control system
a system for controlling the fluid level in a boiler drum has been described here. a feedwater controller is described where the steam flow measurement and water flow measurement are not recognized if they attained the equilibrium condition. the controller provides an improved response in attaining drum level equal to drum level set point. the feedwater control valve (FWCV) controls the level of water in the boiler drum in accordance with a signal output from a control station. Three-element control scheme is implemented. It can maintain water-flow input equal to feedwater demand. The Actual drum level (DL) is sensed by a level transmitter which is then subtracted from a drum level set point (DLSP) as determined by the plant operator.proportional K plus integral action is applied to the error between the drum level and its set point. The summation of the drum level error signal and the steam flow signal becomes the feedwater-demand signal.

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