Conditions for Complete Combustion of Biomass in CFB Boilers
The sign of good combustion in a circulating fluidized bed boiler is that on the premise of no slagging in the furnace, the biomass fuel is combusted as close to complete as possible, while ensuring a faster combustion speed and obtaining the highest combustion efficiency.
1. Adequate supply and suitable air volume.
If the excess air coefficient is too small, that is, the air supply is insufficient, it will increase the solid incomplete combustion heat loss q4 and combustible gas incomplete combustion heat loss q3, which will reduce the combustion efficiency; if the excess air coefficient is too large, it will reduce the furnace temperature , Increase incomplete combustion heat loss. The optimal excess air coefficient makes the sum of q2+q3+q4 the minimum.
2. Increase the furnace temperature appropriately.
According to Arrhenius' law, the combustion reaction rate has an exponential relationship with temperature. On the premise of ensuring that the furnace does not build up slag, try to increase the furnace temperature as much as possible.
3. Good disturbance and mixing in the furnace.
In the fire and combustion phase, it is necessary to ensure that the air and fuel are fully mixed, and in the burnout phase, it is necessary to strengthen the disturbance mixing.
4. The fuel has enough residence time on the grate and in the furnace.
5. Maintain a reasonable flame front position. The flame front should be located in the area between the high-end grate and the middle grate, and the flame is well filled on the grate.
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