Question 69Steam Plants - Assistant Engineer

The correct answer is A) rapid cooling. Boiler refractories that have been previously baked out and fired are most sensitive to rapid cooling. This is because the intense heating process causes the refractory materials to become hardened and brittle. Rapid cooling can cause thermal shock, leading to cracks, spalling, or other damage to the refractory lining. Sustained high furnace temperatures, radiant heat from the burner, and rapid heating are less likely to cause significant damage to these pre-fired refractories.