Column internals distributor

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. 

C. Liquid Distributor (see Figures 4-9). According to Strigle, This is the most important column internal from a process standpoint. A liquid distributor is required at all locations in the tower where an external liquid stream is introduced. High-performance distributors provide a flow rate variation per irrigation point that is a maximum of 5% of the average flow. The geometric uniformity of... 

The liquid distributor is the most important internal structure of a packed column. The distributor strongly influences packing efficiency. It must spread the liquid uniformly, resist plugging/fouling, provide free space for gas flow, and allow operating flexibility. 

Design the column internals plates, distributors, packing supports. 

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

As mentioned in Chapters 2 and 3, peak distortion is caused not only by non-ideal equipment outside but also inside the column. Although sophisticated measurements such as NMR (Tallarek et al., 1998) allow the investigation of the packed bed only, from a practical viewpoint the observable performance of a column always includes the effects of walls, internal distributors and filters. Using the method described in this chapter, these are always contained in an appropriate column parameter (e.g. Dm). The column manufacturer has to ensure a proper bed packing and flow distribution (Chapter 3) and, thus, their negative influence on column performance, and hence on Dm, can assumed to be small. However, these facts should be kept in mind when doing scale-up. 

A. Column Internals. The analogy of brine softening to water softening does not extend to mechanical design. The systems used to soften water are not suitable for our application, where exposure conditions are quite different. More robust construction is necessary. While chemical compatibility with brine is essential, it is not the only consideration. Mechanical and thermal stability is also important. Distortion of a distributor or collecting screen, for example, can allow loss of resin or channeling of fluid. 

The multiple phase contact inside the column is promoted by internal mass transfer equipment. Three groups of mass transfer equipment are commonly differentiated, which are separation trays, random packings and structured packings. Besides mass transfer equipment, further column internals are required in rectification to ensure the proper operation of the mass transfer equipment. Such internals may include support and hold-down plates, liquid distributors and redistributors, vapour distributor devices, gas-liquid phase separators and liquid collectors that usually do not participate on mass transfer. 

CARPT offers possibilities for mapping velocities and turbulence parameters for liquid and solids in bubble columns, ebulated beds, fluidized beds, slurry mixed systems, etc. It allows detection of stagnancies and assessment of distributor designs and column internals on flow pattern and mixing. The use of the technique in high pressure systems is feasible. 

The column internals are these important imte of the apparatus idiidi are cxmstructed to ensure i oper conditions fo oi ration of die packiii Ihere are support plates, hoU-4own phrtes, liquid distributors and redistributors, gas (vapour) distributors, gas-liquid phase separators, and liquid collators. As an additional type of column internals, combined devices rinch ensuring redistribution of the phases act also as mass transfer vices. 

FIG. 14-80 Cost of internal devices for columns containing dumped packings, a) Holddown plates and support plates, (h) Redistributors, (c) Liquid distributors. [Pikulik and Diaz, Cbem. Eng., 84(21), 106 (Oct. 10, 1977).]... 

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... 

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.

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