Question 170Steam Plants - 1st Asst/Chief

The correct answer is C) vanadium and sodium. The most harmful slag forming compounds found in fuel oils are vanadium and sodium. These compounds can lead to the formation of deposits and slag in the engine, which can cause significant damage and operational issues. Vanadium and sodium are known to be highly corrosive and can cause fouling of engine components, leading to decreased efficiency and increased maintenance requirements. The other options are incorrect because calcium and silica (A) are not the primary slag-forming compounds, while iron and sulfur (D) are not as problematic as vanadium and sodium in terms of slag formation. Potassium and nickel (B) are not the most significant slag-forming compounds in fuel oils.