Exam Question
(a) Describe with the aid of a sketch an evaporator for the production of fresh water. (6)
(b) (i) Explain how scale is formed. (5)
(ii) State measures to reduce or remove scale.
(c) Show how the water is made potable. (5)
Class 4 (4th Engineer)
MEP
📅 Aug 2022
Reference Answer
### (a) Description of an Evaporator for Fresh Water Production
A marine freshwater generator (FWG) or evaporator produces high-quality distilled water from seawater using the principle of vacuum distillation. The core concept is that **reducing the pressure above a liquid lowers its boiling point**. By creating a high vacuum inside the evaporator shell, seawater can be boiled at a low temperature (typically 40-60°C), utilizing low-grade waste heat from the main engine's LT Central Cooling Water system.
**(Source: Based on Retrieved Context)**
**Key Components and Operation:**
A marine freshwater generator (FWG) or evaporator produces high-quality distilled water from seawater using the principle of vacuum distillation. The core concept is that **reducing the pressure above a liquid lowers its boiling point**. By creating a high vacuum inside the evaporator shell, seawater can be boiled at a low temperature (typically 40-60°C), utilizing low-grade waste heat from the main engine's LT Central Cooling Water system.
**(Source: Based on Retrieved Context)**
**Key Components and Operation:**
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