Packing vapor injection support

A vapor-distributing support (Fig. 3.10) is a flat perforated plate containing perforated vapor risers. Liquid descends through the floor perforations, while vapor rises through the riser perforations. The bottom portion of the vapor risers is unperforated, so that vapor is injected above the liquid pool on the plate. Sumps are optional and recommended (289) where liquid inventory is to be reduced. The vapor-distributing support combines two internals (a vapor distributor and a support plate) into one. Compared to a vapor distributor, this saves both vertical space and internals costs. On the other hand, obstruction of perforations by pieces of packing and possible liquid overflow into risers may make its vapor distribution quality somewhat lower. 

One design of vapor-distributing support plate uses vapor orifices beneath perforated gas risers (see Figure 10-5). The liquid phase will pool on the horizontal deck to a depth equal to the pressure drop causing flow through the liquid orifices plus the gas-phase pressure drop through the plate. The gas phase will be injected into the packed bed through the perforations in the upper part of the gas risers. The lower part of the gas risers is left unperforated to accommodate the liquid pool. 

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