Could anybody pls give ans of boiler 3 element control system?
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Answer Posted / ecxlsync
in boiler drum level control it uses the three elements
principle wherein it consist of Feed water Flow, actual drum
level and steam flow.
in the feed water line there are two Flow Control Valves (37%and 100%). the 37% is being controlled by single element
(single controller). the SP of single controller is the
actual pressure compensated drum level. if the steam flow
is more than 30% of its designed max flow, drum level
control will shift automatically to three elements control
which is in cascaded mode (two controllers). the output of
primary controller which is compensated by the steam flow
as feed forward control is being fed to the secondary
controller as setpoint for the feed water flow. the output
of secondary controller is sent to 100% FCV to manipulate
the feed water flow.
therefore, 3 elements control is to attain that feed water
flow will be equal to the Steam flow.
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