Distillation and Absorption

O Connell s correlations for bubble-cap tray efficiencies (a) distillation and (b) absorption. 

The correlation for distillation is based on limited data for systems of hydrocarbons and chlorinated hydrocarbons and that for absorption on the performance of hydrocarbon absorbers and the scrubbing of ammonia and carbon dioxide with water. is in units of centipoises H is in units of mole-fraction ratios and p L is the molar density of the liquid solvent (in lb mol/ft ). Note that the gas absorbers generally have much lower plate 

Mass Transfer and Separation Processes Principles and Applications 

Conservative Parameter Values for Batch Extraction Efficiencies of E 0.8 

The effectiveness of staged liquid extraction columns is prone to even greater xmcertainties E may vary from a few percent to 50% or higher. Vendor information and test data become a prerequisite in this case. 

---

As with distillation and absorption, when evaporators and dryers are chosen, no attempt should be made to carry out any optimization at this stage in the design. 

Gas-phase adsorption is widely employed for the large-scale purification or bulk separation of air, natural gas, chemicals, and petrochemicals (Table 1). In these uses it is often a preferred alternative to the older unit operations of distillation and absorption. 

The proper design of distillation and absorption columns depends on knowledge of vapor—Hquid equiHbrium, as do flash calculations used to determine the physical state of streams at given conditions of temperature, pressure, and composition. Detailed treatments of vapor—Hquid equiHbria are available (6,7). 

E. Distillation and absorption, counter-current, random packings, modification of Onda correlation, Bravo and Fair correlation... 

A study of industrial apphcatious by Taylor, Kooijmau, and Woodman [IChemE. Symp. Ser. Distillation and Absorption 1992, A415-A427 (1992)] concluded that rate-based models are particularly desirable when simulating or designing (1) packed columns, (2) systems with strongly uonide liquid solutions, (3) systems with trace compo-... 

Zanker gives this method for distillation and absorption column trays, which is stated to agree well with published data ... 

Reactors with a packed bed of catalyst are identical to those for gas-liquid reactions filled with inert packing. Trickle-bed reactors are probably the most commonly used reactors with a fixed bed of catalyst. A draft-tube reactor (loop reactor) can contain a catalytic packing (see Fig. 5.4-9) inside the central tube. Stmctured catalysts similar to structural packings in distillation and absorption columns or in static mixers, which are characterized by a low pressure drop, can also be inserted into the draft tube. Recently, a monolithic reactor (Fig. 5.4-11) has been developed, which is an alternative to the trickle-bed reactor. The monolith catalyst has the shape of a block with straight narrow channels on the walls of which catalytic species are deposited. The already extremely low pressure drop by friction is compensated by gravity forces. Consequently, the pressure in the gas phase is constant over the whole height of the reactor. If needed, the gas can be recirculated internally without the necessity of using an external pump. 

Sorensen, E., 1997, Distillation and Absorption International Symposium, Institution of Chemical Engineers, UK, p. 643. 

Cross-flow plates are the most common type of plate contactor used in distillation and absorption columns. In a cross-flow plate the liquid flows across the plate and the vapour... 

Packed columns are used for distillation, gas absorption, and liquid-liquid extraction only distillation and absorption will be considered in this section. Stripping (desorption) is the reverse of absorption and the same design methods will apply. 

Sieve plates are used, similar to those used for distillation and absorption. The stage efficiency for sieve plates, expressed in terms the height of an equivalent theoretical stage (HETS), will, typically, range from 1 to 2.5 m. 

Random packings are also used they are the same as those used in packed distillation and absorption columns. The properties of random packings are given in Table 11.3. Proprietary structured packing are also used. 

Mulet A, Corripio AB and Evans LB (1981) Estimate Costs of Distillation and Absorption Towers Via Correlations, Chem Eng, Dec 77. 

The mechanism of transfer of solute from one phase to the second is one of molecular and eddy diffusion and the concepts of phase equilibrium, interfacial area, and surface renewal are all similar in principle to those met in distillation and absorption, even though, in liquid-liquid extraction, dispersion is effected by mechanical means including pumping and agitation, except in standard packed columns. 

Revision of the nomenclature for the underflow streams of washing thickeners to bring it into line with that used for other stagewise processes, including distillation and absorption (Chapter 10). 

P. Mizsey and Z. Fonyo. Energy integrated distillation system design enhanced by heat pumping distillation and absorption. Inst. Chem,. Eng., pages B69-B75, 1992. 

Institution of Chemical Engineers, Distillation and absorption 92, EFCE Publications Series 94, Symposium Birmingham (September 1992). 

Distillation and absorption towers Distillation tray towers Absorption tray towers... 

Distillation and absorption towers, tray and packed (Evans et al., 1984) prices in ... 

L.B. Evans, A. Mulet, A.B. C orripio, and K.S. Chretien, Costs of pressure vessels, storage tanks, centrifugal pumps, motors, distillation and absorption towers, in Ref. 2, pp. 140-146, 177—183. 

---