Regarding the back pressure of the boiler furnace when selecting burners
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When selecting a burner, the back pressure in the furnace must be taken into account; what are the effects of varying levels of this value? What is the impact of combustion on efficiency or on other things?
This post was last edited by dongjiang1001 on 2012-4-7 at 18:46. Different back pressures in the furnace require specific choices for burners and fans; otherwise, it will be impossible to achieve the required power levels, or even ignition may not occur!
Abnormal back pressure in the furnace can lead to burner flashback, unstable combustion, safety issues, and failure to meet the requirements of the temperature field.
Back pressure is essentially the furnace resistance at full load. If the back pressure is too low, the resistance is small, and the burner can easily reach full load. However, the flame in the furnace tends to be longer. With low resistance, the flow velocity of the flue gas over the heat-exchanging surfaces is necessarily low, resulting in reduced heat transfer efficiency; hence, the efficiency is lower for the same heat exchange area. Excessively high back pressure results in high resistance; the burner may experience insufficient air flow due to this high resistance, which affects the load. Vibration and noise levels in the burner increase significantly, but generally the heat exchange efficiency remains high. However, it is also necessary to consider the change in flame shape when the back pressure changes. At high back pressures, the flame becomes thicker and shorter, resulting in poor filling of the furnace chamber, which in turn leads to a decrease in heat exchange efficiency.
The back pressure in the furnace is an important factor in selecting a burner; what corresponds to this is the burner’s head pressure. Only by choosing the right head pressure can the shape of the flame, the combustion power, and the flow rate of the flue gas be ensured.