Question 367Steam Plants - Assistant Engineer70% to pass
Calcium minerals in boiler water are precipitated out of solution by the use of which of the listed chemicals?
AI Explanation
The correct answer is C) Sodium phosphate.
Sodium phosphate is commonly used to precipitate calcium minerals, such as calcium carbonate and calcium sulfate, out of boiler water. These minerals can form scale on the inside of boiler tubes, reducing heat transfer efficiency and potentially leading to damage. By adding sodium phosphate to the boiler water, it reacts with the dissolved calcium ions to form an insoluble calcium phosphate precipitate that can be removed, preventing scale buildup.
The other options are incorrect because: A) Sodium hydroxide is used to raise the pH of boiler water, but does not specifically precipitate calcium minerals. B) Caustic soda is another name for sodium hydroxide. D) Phenolphthalein is an indicator dye used to determine pH, not a chemical used for water treatment.
Related Questions
#365 A water-tube boiler can be laid up either wet or dry. If it is to be laid up wet, you should _______________.#366 When a boiler water test indicates a pH value of 6, you should _______________.#368 Scale prevention in boiler water is accomplished by adding treatment chemicals to _______________.#369 The major reason dissolved gases are removed from boiler feed water is because they may cause _______________.#370 An adequate phosphate reserve should be maintained in boiler water to _______________.