The process
A circulating fluidised bed boiler recirculates solids through a hot cyclone and loop seal. The primary air fan runs at high pressure to fluidise the bed, the secondary air fan stages combustion, and the ID fan handles the flue gas after the cyclone and ESP. Loop seal and fluidising blowers add high pressure duties around the furnace.
The gas at the fan
Circulating fluidised bed boilers return most solids through the cyclone, so the flue gas reaching the fan carries fine ash at moderate loading. Erosion is slower than on an AFBC unit but still sets the wheel design.
Selection for this duty
| Construction | Absorptive annular design in mild steel; stainless steel where the gas is wet or corrosive |
| Density at the fan | At about 150°C the gas density is close to 0.83 kg/m³, 69% of standard air. Pressure developed and power drawn fall in the same ratio, so the selection is made at this density and the motor is checked at cold start. |
Cuts the noise from steam or gas expanding from high pressure to atmosphere at safety valve outlets, start-up vents and blow-down lines. Client-stated blade types for the Vent Silencer in general: Silencer.
Industries
Other fans in cfbc boilers
Vent Silencer in other processes
Information needed to select or quote
- Gas volume and temperature. Actual flow at the inlet, normal and upset temperature, moisture.
- Dust or pollutant. Inlet loading, particle size distribution, whether it is abrasive, sticky, hygroscopic or combustible; for gases, the species and concentration.
- Required outlet. The emission limit or clean gas concentration the unit must meet.
- Site. Available space and height, material of construction preferences, and how the collected material is to be discharged.