Exam Question
With regards to Boiler water level Control, explain the following.
(a) Shrink and Swell phenomenon
(b) Cascade Control
(c) Split Control
(d) Condensing chamber - function and location.
Class 2 (2nd Engineer)
MEKG
📅 Mar 2018
Reference Answer
### (a) Shrink and Swell Phenomenon
The shrink and swell phenomenon refers to the false or misleading boiler drum water level indications caused by rapid changes in steam demand and the corresponding pressure fluctuations within the drum. A level control system that does not account for this can take incorrect corrective actions, leading to hazardous conditions.
**(i) Swell (Apparent Rise in Level)**
* **Cause**: A sudden increase in steam demand (e.g., during main engine maneuvering or start-up of a large consumer like a cargo pump turbine).
The shrink and swell phenomenon refers to the false or misleading boiler drum water level indications caused by rapid changes in steam demand and the corresponding pressure fluctuations within the drum. A level control system that does not account for this can take incorrect corrective actions, leading to hazardous conditions.
**(i) Swell (Apparent Rise in Level)**
* **Cause**: A sudden increase in steam demand (e.g., during main engine maneuvering or start-up of a large consumer like a cargo pump turbine).
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