With reference to Boiler feed regulation:
(a) Describe, with the aid of sketches, the operation of a boiler feed water regulator controlled by at least two other parameters besides water level in the drum.
(6)
(b) Give reasons for the inclusion of the other elements besides water level in controlling feed flow.
(6)
(c) Deduce the possible effects on the system when the drain valve in the constant leg in the level transmitter starts to leak.
(4)
Reference Answer
### (a) Operation of a Three-Element Boiler Feed Water Regulator A three-element boiler feed water regulator provides precise control of the boiler drum water level by measuring and comparing three critical parameters: **Drum Water Level**, **Steam Flow Rate**, and **Feed Water Flow Rate**. This system is essential for boilers subject to rapid or large load changes. **1. Components and Measurement:** * **Drum Level Transmitter:** A Differential Pressure (DP) transmitter measures the hydrostatic head difference between a 'constant leg' (a reference column of cooled condensate) and a 'variable leg' connected to the boiler drum. The measured DP is directly proportional to the water level.
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