Packing support

Packing supports must perform the following functions  

Incorporate sufficient open area in order to permit unrestricted flow of liquid and vapor 

Packing supports therefore must provide both a high fraction of open area and the required mechanical strength. 

Open areas provided by modem packing supports are usually of the order of 70 to 100 percent of the column cross-sectional area (74, 257, 305). The open area depends on the materials of construction and the column diameter some common designs in ceramic, carbon, and plastic have open areas smaller than 65 percent (214, 257, 305). 

In mildly corrosive applications it often pays to fabricate the packing support from stainless steel, even when carbon steel is satisfactory for the packing. This prevents localized corrosion that can puncture holes in the support, resulting in downward migration of packings. One service where this technique is commonly applied is in natural gas plant glycol-regeneration stills (84). 

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An advantage of pack carburizing is that the charcoal pack supports the workload which minimizes distortion. However, the components must be removed from the pack for quenching, or the mass cooled to room temperature and then the components reaustenitized and quenched. 

As indicated above, packed column internals include hqiiid distributors, packing support plates, redistributors (as needed), and holddown plates (to prevent movement of packing under flow conditions). Costs of these internals for columns with random packing are given in Fig. 14-80, based on early 1976 prices, and a Marshall and Swift cost index of 460. 

Figure 2. Multibeam packing support plate. (Courtesy of Norton Chemical Process Products Corporation.)...

Figure 14, Cross-partition rings used as packing supports.

Adsorbers, distillation colunuis, and packed lowers are more complicated vessels and as a result, the potential exists for more serious hazards. These vessels are subject to tlie same potential haz. uds discussed previously in relation to leaks, corrosion, and stress. However, llicse separation columns contain a wide variety of internals or separation devices. Adsorbers or strippers usually contain packing, packing supports, liquid distributors, hold-down plates, and weirs. Depending on tlie physical and chemical properties of the fluids being passed tlirough tlie tower, potential liazards may result if incompatible materials are used for llie internals. Reactivity with llie metals used may cause undesirable reactions, which may lead to elevated temperatures and pressures and, ullinialely, to vessel rupture. Distillation columns may contain internals such as sieve trays, bubble caps, and valve plates, wliicli are also in conlacl with tlie... 

Pressure Drop Across Packing Supports and Redistribution Plates... 

Useful correlated information on pressure drop across packing supports and redistribution plates is practically not available. Some order of magnitude guide data is given in Figures 9-37-41. 

This bed should be in three sections (two might be acceptable under some circumstances, or if different packing were used) thereby requiring two intermediate combined packing supports and redistribution plates and one bottom support plate. 

The packing support consists of a floor grating material with bar openings spaced to give 57.5% free void area of cross-section. 

Design the column internals plates, distributors, packing supports. 

Select and design the column internal features packing support, liquid distributor, redistributors. 

The best design of packing support is one in which gas inlets are provided above the level where the liquid flows from the bed such as the gas-injection type shown in Figure 11.46... 

A full redistributor combines the functions of a packing support and a liquid distributor a typical design is shown in Figure 11.52. 

An estimate of the amount of liquid held up in the packing under operating conditions is needed to calculate the total load carried by the packing support. The liquid hold-up will depend on the liquid rate and, to some extent, on the gas flow-rate. The packing manufacturers design literature should be consulted to obtain accurate estimates. As a... 

Cost of solvent extraction auxiliaries Cost of absorbtion and distillation column packing, supports and distributors Cost of tanks (surge, etc.)... 

Effect of bed support. The structure of the bed, and hence K", is markedly influenced by the nature of the support. For example, the initial condition in a filtration may affect the whole of a filter cake. Figure 4.3 shows the difference in orientation of two beds of cubical particles. The importance of the packing support should not be overlooked in considering the drop in pressure through the column since the support may itself form an important resistance, and by orientating the particles as indicated may also affect the total pressure drop. 

If the vessel s internal packing supports can handle the additional weight, create a shallow pool of water above the packing and below the work area by using plastic sheeting appropriately supported by metal sheets cut to fit the interior of the vessel. 

Anaerobic Filter. An anaerobic filter consists of packed support media that traps biomass as well as facilitates attached growth of biomass as a biofilm (Fig. 8). Such a reactor configuration helps in the retention of suspended biomass as well as gas-liquid-solid separation. The flow of liquid can be upward or downward, and treatment occurs due to attached and suspended biomass. Treated effluent is collected at the bottom or top of the reactor for discharge and recycling. Gas produced in the media is collected underneath the bioreactor cover and transported for storage or use. Volumetric loading rates vary from 5 to 20 kg COD/m day with HRT values of 0.5-4 days. 

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