Column internal

The column inventory also can be reducdd by the use of low-holdup column internals, including the holdup in the column base. As the design progresses, other features can be included to reduce the inventory. Thermosyphon reboilers have a lower inventory than kettle reboilers. Peripheral equipment such as reboilers can be located inside the column. ... 

In the case of a packed column, the terms on the right-hand side should each be divided by the voidage, ie, the volume fraction not occupied by the soHd packing (71). In unpacked columns at low values of the sHp velocity approximates the terminal velocity of an isolated drop, but the sHp velocity decreases with holdup and may also be affected by column internals such as agitators, baffle plates, etc. The sHp velocity can generally be represented by (73) ... 

Aluminum geodesic dome roof tanks are becoming popular. These are often the economic choice. They offer superior corrosion resistance for a wide range of conditions, and are clear span stmctures not requiring internal supports. They can also be built to any required diameter. However, domes caimot handle more than a few inches of water column internal or external pressure. 

The mixture to be separated is clear, nonfouling, and free of solids, and cleaning of column internals will not be necessary. 

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. 

Typical packed column internals are shown in Figures 2-11. 

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... 

Figure 1. Packed column internals. (Reprinted by special permission from Chemical Engineering, March 5, 1984, copyright 1984 by McGraw-Hill, Inc.)...

Zister, H. Z., C. E. Refresher Column Internals Parts 1-7, Chem. Eng., Series beginning May 19, 1980. Branan, C. R., The Fractionator Analysis Pocket Handbook, Gulf Publishing Co., Houston, Texas, 1978. 

The column internals are housed within a vertical shell, and together with the condenser and reboiler, constitute a distillation column. A schematic of a typical distillation unit with a single feed and two product streams is shown in Figure 1. 

Column internals that minimize holdup without sacrificing operation efficiency (Dale, 1987). 

Column internal diameter Volumetric flow rate Injection volume UV-deteaor cell volume Sensitivity improvement... 

For a binary mixture the values of x and y can be obtained from the equilibrium curve. Select values of x and read the corresponding value of y from the equilibrium curve. Tabulate values of l/(y - x), and plot versus X], resulting in a graphical integration of the function dx (y - x) [130] between x and xj. This system would have no column internals and no reflux. 

To determine the column (with trays) diameter, an approach [130] is to (1) assume 0 hours (2) solve for V, Ib/hr vapor up the column at selected, calculated, or assumed temperature and pressure (3) calculate column diameter using an assumed reasonable vapor velocity for the type of column internals (see section in this volume on Mechanical Designs for Tray Performance ). 

Liquid mass velocity, Ib/hr-ft" based on superficial cross section of column Internal reflux ratio, dimensionless Weir length, in. 

Pareek, V., M.P. Brungs, and A.A. Adesina, Photocausticization of Spent Bayer liquor A Pilot-Scale Study. Advances in Environmental Research, 2003. 7(2) p. 411-420. Bertola, F., M. Vanni, and G. Baldi, Application of Computational Fluid Dynamics to Multiphase Flow in Bubble Columns. International journal of Chemical Reactor Engineering, 2003. 1 p. A3. 

INFLUENCE OF COLUMN INTERNAL DIAMETER ON EFFICIENCY AMD SEPARATION TIME FOR OPEN TUBUALR COLUMN SUPERCRITICAL FLUID CHROMATOGRAPHY. 

Column Column Internal Peak VarlMce Peak Volusn ... 

Design the column internals plates, distributors, packing supports. 

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

As an example, one very common retrofit situation is the replacement of distillation column internals to improve the performance of the column. The improvement in performance sought is often an increase in the throughput. This calls for existing internals to be removed and then to be replaced with the new internals. Table 2.8 gives typical... 

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