Distillation columns liquid distribution

The entrance of a liqmd-flashing vapor mixture into the distillation column feed location requires a specially designed distribution tray to separate the vapors from the liquid, w hich must drop onto the packing bed for that section in a uniform pattern and rate. 

Later we measured the concentrations of n-propyl, isobutyl, and the combined isoamyl and active amyl alcohols (3-methyl-l-butyl alcohol and 2-methyl-l-butyl alcohol) in distillation tray liquids using a gas chromatographic method with n-butyl alcohol as the internal standard. The distribution of the higher alcohols in the 14-tray concentrating section of a 12-inch pilot column during a run in which the product from tray 7 was 169° proof is shown in the upper portion of Figure 4. The... 

Traditionally, packings have not been used in distillation duties, except for small columns of less than 1 m diameter, and even less for high pressure service. The situation has changed over the last 10-15 years, partly through a better understanding of how packed towers work, particularly with respect to liquid distribution, but also through the development of new proprietary packings. 

The mixture to be separated and analyzed may be either a gas, liquid, or a solid in some instances. All that is required is that the materials be stable, have a vapor pressure of 0.1 torr at the operating temperature and interact with the column material (either a solid adsorbent or a liquid stationary phase) and the mobile phase (carrier gas). The result of this interaction is the differing distribution of the sample components between the two phases, resulting in the separation of the sample components into zones or bands. The principle that governs the chromatographic separation is the foundation of most physical methods of separation, for example, distillation and liquid-liquid extraction. 

The concept of plate theory was originally proposed for the performance of distillation columns (12). However, Martin and Synge (13) first applied the plate theory to partition chromatography. The theory assumes that the column is divided into a number of zones called theoretical plates. One determines the zone thickness or height equivalent to a theoretical plate (HETP) by assuming that there is perfect equilibrium between the gas and liquid phases within each plate. The resulting behavior of the plate column is calculated on the assumption that the distribution coefficient remains unaffected by the presence of other... 

Similarly, a distillation line map (DLM) shows the distribution of liquid composition on the stages of a continuous distillation column at infinite reflux and for infinite number of stages. DLM is obtained even simpler by computing successive dew and bubble points as described by the relation ... 

The last step regards the detailed design of the reactive-distillation column and of other operational units. The hydraulic design is consolidated taking into account the optimal traffic of liquid and vapor. Additional internals are provided to ensure uniform distribution of fluids and a sharp residence-time distribution. 

Extractive distillation is used because the components are distributed differently between contacting liquid and vapor phases in equilibrium when a high-boiling nonideal component is added to the mixture. The added component is introduced in the upper part of a distillation column above the feed and remains in appreciable concentration in the liquid on all of the lower trays. It is removed from the column with one of the components being separated as the bottoms product. Although a nonideal component is also introduced for azeotropic distillation, the added com-... 

Distillation columns often consist of a series of vertically distributed stages. Vapor flows upward and liquid flows downward between adjacent stages some of the liquid fed to each stage vaporizes, and some of the vapor fed to each stage condenses. A representation of the lop section of a distillation column is shown on the next page. (See Problem 4.26 for a more realistic representation.)... 

The performance of OCFS as mass transfer devices is heavily dependent on the quality of the distribution of the gas and liquid phases across the column upon entry to the packed section—irrespective of whether its function is purely rectification/stripping or chemical conversion also. Optimal liquid distribution is, however, of additional importance in catalytic distillation, in ensuring contacting of reactants with the catalyst. 

Gas absorption can be carried out in a column equipped with sieve trays or other types of plates normally used for distillation. A column with trays is sometimes chosen instead of a packed column to avoid the problem of liquid distribution in a large diameter tower and to decrease the uncertainty in scaleup. The number of theoretical stages is determined by stepping off plates on a y-x diagram, and the number of actual stages is then calculated using an average plate efficiency. The plate and local efficiencies are defined in the same way as for distillation [Eqs. 

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