The Pneumatically Actuated Pulse Feeder

The stop plate is adjusted to a height so that the angle its rim makes with that of the downcomer is always less than the angle of repose of the solids used. In this manner, the solids in this peripheral zone do not flow while no air issues from the central tube, and are splashed radially outward by air puffs during the on-period of the solenoid valve. 

It has been found that the solids feed rate is generally linear with the frequency of the solenoid valve, as shown by a typical calibration curve shown in Fig. 27. 

Normally the pneumatically controlled pulse feeder operates with limited pressure difference between the hopper and the stop plate. When the pressure difference is in the direction opposite to that of the downward solids flow, the downcomer needs to be lengthened in order to seal the solids, or else other modes of downcomer design must be resorted to. 

When two units of the ring internals were installed at H — 2.25 m and H = 4.75 m, the dense-phase region was cut into three layers with a dilute influence zones in between and was thereby itself extended upward, while the solids inventory remained the same. Voidages e for the dilute-phase region and ea for the dense-phase region remain essentially the same, as shown in Fig. 31. In the influence zone of the internals, the radial voidage distribution is considerably flattened, as shown in Fig. 32. Reduced solid concentration in an influence zone is instrumental in suppression of solids mixing between adjacent dense-phase layers. 

Primary cyclone Solids-gas disengager Gas pressure taps 

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