Question 72Steam Plants - Assistant Engineer

The correct answer is C) large and rapid changes in furnace temperature. The useful life of furnace refractory, which is the heat-resistant material lining the inside of a furnace, is most affected by large and rapid changes in furnace temperature. Sudden temperature fluctuations can cause the refractory material to expand and contract, leading to cracking, spalling, and accelerated deterioration. This is a key factor that impacts the lifespan of the refractory lining. The other options are incorrect because they do not have as direct an impact on the refractory as the rapid changes in furnace temperature. The quality of the fuel, improper boiler water treatment, and high steady steaming loads can affect other aspects of furnace operation, but they are not the primary drivers of refractory degradation.