🔍 Key Concepts
• complete combustion requirements (correct fuel/air ratio, proper mixing, and time at temperature)
• role of forced draft fans in supplying air for combustion in marine boilers
• what actually determines when you can no longer increase firing rate safely without causing smoke, soot, or unburned fuel
💭 Think About
• When you increase boiler load (fire harder), which part of the system is most likely to become the bottleneck: the burner shape, the sprayer plate size, the fuel pressure, or the supply of air?
• Which choice, if limited, would first cause incomplete combustion (smoke, soot, black stack) when you try to increase firing rate?
• Think about which item, when at its maximum, prevents further safe increase in combustion rate, even if the others could still be increased.
✅ Before You Answer
• Identify which factor directly controls how much oxygen is available to burn additional fuel.
• Consider which item is usually adjustable (can be changed or swapped) versus which is a fixed system capacity limit on the boiler as installed.
• Ask: At high firing rates, what problem appears first in practice on a marine boiler: loss of proper burner shape, inability to increase fuel pressure, or insufficient air for clean combustion?