Answer / earnest

Boiler 3- element control system: (1)Boiler feed water (2)
drum level (3) steam flow

Answer / visakh ctjv

Boiler 3-element system consists of boiler feed water
system, drum level system and steam flow system. working of
this system is based on cascade control
ie, output of one system is use as setpoint of another

Answer / 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.

Answer / k.suresh

1)Boiler feed water 2)Drum level 3) Steam flow

Answer / naik muhammad

Most boilers of medium to high pressure today use a “3-
element” boiler control strategy. The term “3-element
control” refers to the number of process variables (PVs)
that are measured to effect control of the boiler feedwater
control valve. These measured PVs are:
▪ liquid level in the boiler drum,
▪ flow of feedwater to the boiler drum, and
▪ flow of steam leaving the boiler drum.

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