Exam Question

### (a) Effects of Taking Fresh Water from Shore as Feedwater for Auxiliary Boilers
Taking fresh water from shore for use as boiler feedwater without adequate pre-treatment can introduce a range of harmful impurities into the boiler system, leading to severe operational issues and potential damage. The primary effects are due to the presence of dissolved solids, suspended solids, dissolved gases, and organic matter:
* **Scaling (Fouling)**:
* **Mechanism**: Shore fresh water often contains hardness salts, primarily calcium (Ca²⁺) and magnesium (Mg²⁺) carbonates, bicarbonates, sulfates, and chlorides. When heated inside the boiler, these salts precipitate out of solution, forming hard, adherent deposits (scale) on heat transfer surfaces (e.g., boiler tubes).