Why do the intermediate and high burner nozzles have higher capacities than the primary burner nozzle in a boiler burner with three fixed capacity nozzles?

The intermediate and high burner nozzles have higher capacities than the primary burner nozzle primarily to enhance combustion efficiency. In a boiler burner system, the primary nozzle is designed to handle the lower power demands during initial operation or startup phases, while the intermediate and high nozzles are intended for more demanding conditions that require greater fuel flow to maintain optimal performance.

When a boiler operates at higher capacities, particularly during peak load conditions, the intermediate and high nozzles allow for a higher volume of fuel and air to be mixed and combusted. This is crucial for maintaining the right fuel-to-air ratio and ensuring complete combustion, which in turn maximizes the efficiency of the boiler. Enhanced combustion efficiency reduces unburned fuel, promotes better heat transfer within the boiler, and ultimately contributes to lower emissions and better overall operation.

Therefore, the design and capacity differences among nozzles in a multi-nozzle system are strategically made to ensure optimal performance across various operating conditions, focusing on effectiveness in combustion processes at different levels of boiler output.