Distillation columns spray contacting

Direct-contact condensers (Fig. 15.14f). These are used for minimizing pressure drop in vacuum condensation. To accomplish this, the direct-contact zone contains low-pressure-drop internals such as packings, or is a spray chamber. Another common application is intermediate heat removal ("pumparounds ) in refinery fractionators. Here the main purpose is to maximize heat recovery at the highest possible temperature levels. A third common application is intermediate heat removal from absorbers or reactive distillation columns in which an exothermic reaction takes places. In all these applications, condensation... 

Figure 2.1.2. Some examples of the nature of contact between various feed and product streams, (a) Membrane separates air into two product streams in a single-entry separator, which is a silicone membrane permeator for air separation, (b) Limited contact between vapor and liquid products in a sieve plate (the separator) in a distillation column, (c) Complete contact between a feed scrubbing liquid stream introduced as drops in a spray and the product gas stream after scrubbing.

Many chemically processed materials occur as a mixture of different components in gas, liquid, or solid phases. In order to ranove one or more components from its original mixtures, it must be contacted with another phase. There are several conventional and established methods used in the industry to separate them, which includes distillation, leaching, absorption, adsorption, ion exchange, chromatography, crystallization, and extraction [1], These established processes incorporate a variety of geometrical and flow configurations such as packed columns, spray columns, and bubble-tray columns in various phases, which include gas-liquid, liquid-liquid, vapor-liquid, or solid-Uquid phases. 

Heat transfer, dehunrtidification, absorption, distillation, and extraction operations in general involve two-film resistances. Where there is direct contact between the two fluid streams as in packed or spray columns, the use of an overall value of H.T.U. greatly simplifies calculations... the overall H.T.U. and resulting column height do not vary from one of these systems to another as much as might be supposed. 

A combination of flash evaporators, direct-contact condensers, and liquid-liquid exchangers has been described by Othmer (01). In this process water vapors, produced in a multistage flash distillation of heated sea water at successively reducing pressures, are condensed by direct contact with a recycle steam of product water. The heat is from the hot product water and is recovered by an immiscible petroleum oil in one spray column and transferred to the incoming sea water feed in a second spray column. 

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