Multi-inlet cyclone

Mirzaie, H., and N. Syred. 1989. The use of multi inlet cyclone combustor to minimize NOj formations. 3rd Symposium (International) of Gas-Solid Flows— 1989 Proceedings. San Diego, CA (presented at the 3rd Joint ASCE/ASME Mechanics Conference). 

An integral CFB (ICFB) was thus proposed to combine the four major component parts in a single concentric-tube structure the fast bed, a circular V-valve (CV-valve), an internal multi-inlet cyclone and its dipleg (Liu, 1990 Kwauk et al, 1991). 

For the annular-fast-bed design shown in Fig. 35a, solid particles elutriated from the fast bed are separated in a multi-inlet cyclone (MIC) they then descend through a mildly fluidized dipleg and are recirculated to the fast bed via a circular V-valve (CV-valve). Fluidizing air is supplied separately to the fast bed and the dipleg. 

Figure 38 (Liu et al., 1990b) shows a four-inlet cyclone. Solids tend to be densified around the inlet region as the vertically entering solids-laden streams are suddenly diverted toward tangential flow in a horizontal plane. At inlet velocities exceeding 8.5 m/s, the overall separation efficiency for a typical FCC catalyst was found to be consistently above 99%, as shown in Fig. 39. This design, however, resulted in relatively high pressure drop unless the inlets were appropriately enlarged. The efficiency and pressure drop of this type of multi-inlet cyclones could be approximated by modifying the single-inlet cyclone expressions (Kou, 1987 Shi et al., 1987) ...

A second type of multi-inlet cyclone, shown in Fig. 38b, consists of radial vanes to direct solids issuing from a central fast bed in axial upflow (see Fig. 35b) peripherally into an annular dipleg. A single stage of such radial vanes often gives an efficiency of 95% for an FCC catalyst with an average particle size of 54 fim, and the pressure drop is low. For higher separation efficiency, a series of vanes could be employed. 

---