Question 195Steam Plants - 1st Asst/Chief70% to pass
In a water-tube boiler, waterside scale formation is caused by _______________.
AI Explanation
The correct answer is C) calcium sulfate.
In a water-tube boiler, waterside scale formation is caused by the precipitation of dissolved minerals, primarily calcium sulfate (CaSO4), also known as gypsum. As the boiler water is heated, the solubility of calcium sulfate decreases, leading to its deposition on the boiler's internal surfaces, forming a hard, insulating scale.
The other options are incorrect because:
A) Sodium hydroxide (NaOH) is a caustic substance used to control the pH in boiler water, not a cause of scale formation.
B) Sodium phosphate is a water treatment chemical used to prevent scale, not a cause of it.
D) Magnesium phosphate is also a water treatment chemical, not a contributor to scale formation.
Related Questions
#193 Blisters developing on boiler tubes can be caused by _______________.#194 Boiler tube failures can result from _______________.#196 The formation of a pit in the surface of a boiler tube is most likely to occur when _______________.#197 Fireside burning of boiler tubes is usually the direct result of _______________.#198 Cratering and water tracking in boiler tubes is caused by _______________.