Boiler Drum Level Control Loop

This diagram represents a single-element boiler drum level loop. Feedwater enters through V-101, while steam leaves the boiler outlet. LT-101 senses level in the boiler and transmits that value to LIC-101. The controller changes the diaphragm-operated feedwater valve to restore the target level. The fail-closed valve position is shown as part of the control design and should be reviewed against the plant safety philosophy. Single-element level control suits relatively steady loads and is a useful drawing for teaching the relationship between measurement, control, and the final element. A detailed boiler P&ID would also include shutdown trips, feed pumps, blowdown, safety valves, and additional instruments.

種類 P&ID規格 ANSI/ISA-5.1-2009 + ISO 10628-1:2014エンジン schematex-pid更新日 2026/9/24

依頼内容

“A steam boiler with a level transmitter on the drum, a level controller, and a fail-closed feedwater control valve feeding the boiler.”

次はこちらAdd a low-level alarm switchAdd a feedwater flow transmitter

この図に含まれるもの

図の背後にある意思決定を読み解く。

01Measured variable

Sense water level in the boiler drum.

02Manipulated variable

Adjust feedwater flow with V-101.

03Safe position

Close the feedwater valve on actuator failure.

04Signal path

Send level electrically to the controller and valve output pneumatically.

Use this simplified loop for a basic boiler feedwater concept; larger boilers may require three-element control.

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よくある質問

What is single-element drum control?

It controls feedwater from one measurement: the boiler drum level.

What does LIC-101 do?

It compares the measured level to its setpoint and moves the feedwater valve.

When is more control needed?

Fast-changing boiler loads often use steam-flow and feedwater-flow measurements as well.