Column hold-down plate type

The hold-down plates type HP-P [1] are used in combination with structured packings, lie on top of teem and are stayed at tee column wall. They are intended to prevent movement in tee packed bed. The liquid distributor used together with packing is supported on tee metal HP-P Hold-down plates by adjustable bolts, thus making a support ring structure unnecessary. 

Figure 1335. Packed column and internals, (a) Example packed column with a variety of internals [Chen, Chem. Eng. 40, (5 Mar. 1984)]. (b) Packing support and redistributor assembly, (c) Trough-type liquid distributor, (d) Perforated pipe distributor, (e) Rosette redistributor for small towers. (0 Hold-down plate, particularly for low density packing.

In some cases of accidentol flooding or motion due to pressure surges in the column, it is possible that a part of the packing, usually of the random one, is swept aw by the flow of the vapour. In order to pievmt such accidents special hold-down plates mounted over the packing, manufictured in metal and plastic are used. L er some constnictions of these types will be considered. 

The hold-down plate Raschig Grid type RG [1] presented in Figs. 21 and 22 is also offered for column diameters 500 to 3000 mm. 

The separation operation called distillation utihzes vapor and hquid phases at essentially the same temperature and pressure for the coexisting zones. Various lands of devices such as r andom or sti uctui ed packings and plates or tr ays are used to bring the two phases into intimate contact. Trays are stacked one above the other and enclosed in a cyhndrical shell to form a column. Pacldngs are also generally contained in a cyhndrical shell between hold-down and support plates. A typical tray-type distillation column plus major external accessories is shown schematically in Fig. 13-1. 

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