Hopper Venting Options

It is frequently necessary to install a cyclone atop a solids receiving vessel or hopper. Often the solids within the hopper must be aerated so that they will freely flow out the bottom of the hopper and not compact. The issue which then arises is, How does one handle the vent gas As shown in Fig. 11.6.1, several options exist, and we shall briefly enumerate and discuss these below. 

B Pipe discharge into hopper with vent iine to overfiow 

E Direct discharge into hopper with wide cone opening 

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Vent to suitable filter unit - this can be optional on sealed units where the volume of air is low and the discharge is directly to a hopper by a sealed route. Otherwise the unit filters any entrained product from the air. The filtered material can be cleaned from the filter unit and discharged directly back into the process. 

Option C.—If one attempts to vent the hopper back to the cyclone s inlet pipe or duct two problems can occur. First, the higher pressure in the inlet piping will force some of the inlet gases and solids to flow down into the hopper. This gas, along with some fraction of the solids conveyed downwards... 

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