Stripping distillation

G. Absorption, stripping, distillation, counter-current. Hi, and Hq, random packings, Cornell et al. correlation, and Belles and Fair correlation... 

Stripping has the technical advantage that the expensive rhodium catalyst remains in the reactor and the disadvantage that the least volatile component (acetic acid) has the lowest concentration of all components in the gas removed by stripping. Distillation as a separation method has the advantage that acetic acid is the most abundant component in the liquid, but now rhodium will be circulated in the system and will remain in the bottom of the distillation unit and it should not precipitate anywhere ... 

However, in general, solvent recovery is an important step in the overall solvent extraction process. Solvent recovery from the raffinate (i.e., water phase) may be accomplished by stripping, distillation, or adsorption. The extract, or solute-laden solvent stream, may also be processed to recover solvent via removal of the solute. The solute removal and solvent recovery step may include reverse solvent extraction, distillation, or some other process. For example, an extraction with caustic extracts phenol from light oil, which was used as the solvent in dephenolizing coke plant wastewaters (4). The caustic changes the affinity of the solute (phenol) for the solvent (light oil) in comparison to water as will be explained in the equilibrium conditions section. Distillation is more common if there are no azeotropes. 

This chapter deals with the diffusional transfer of mass to and across a phase boundary. In particular, gas-liquid, gas-solid, and liquid-liquid phase combinations have been considered. Process applications include absorption, stripping, distillation, extraction, adsorption, and the diffusional aspects of chemical reactions on a solid surface. For steady-state transfer operations, the rates of mass transfer can be correlated by variations of Pick s first law, which states that the rate is directly proportional to the concentration driving force and the extent of interfacial area, and inversely proportional to the distance of movement of the mass to the interface. 

DISPOSAL AND STORAGE METHODS solutions of 1% phenol may be recovered by steam stripping, distillation, or carbon adsorption dilute large amounts with flooding quantities of water and feed to sewage organisms cautiously ignite small amounts store in a cool, dry location separate from oxidizers and acute fire hazards. 

FIGURE 31.24 Theoretical and experimental transport of Cs(I) through HFSLM feed Cs(I) in 3 M HNO3 strip distilled water carrier solvent varying concentrations of calix-naphthocrown-6 (CNC) in 80% NPOE + 20% n-dodecane flow rate 200 mL/min. (Reproduced from Kandwal, P. et al, Chem. Eng. J., 174,110, 2011. With permission.)... 

In the extractor (E) acetic acid, furfural, formic acid, and methanol are extracted from the organics through a polar organic solvent mix. The extractant is a mixture of tri-n-octylphosphineoxide (CAS 78-50-2) and imdecane (CAS 1120-21-4), which does not dissolve in the condensate. The solvent extraction step is able to remove 85—90% of the organic compotmds.The aqueous raffinate is purified and can be used as a fresh water substitute in the pulp mill. The solvent extract is transferred into a flash vessel where most of the water is removed. Afterward, the raw product is removed from the solvent extract by a stripping distillation (S). While the solvent is supplied to the extractor again, the acetic acid and furfural-rich overhead stream (raw product) is forwarded to a number of rectifying columns in which by-products are removed and the final product is purified to the required quality. ... 

For absorption or stripping distillation columns, the most commonly-used plates are perforated plates, because they are cheapest to make and of well-established design. 

The objective of the bottoms stripper is to strip distillate from the flash zone liquid, revaporize residual distillate that may be in the spent wash, and correction of bottoms flash. The bottom stripper typically has a design of 4 to 6 bubble cap trays or sieve trays. Some of the newer designs are using packing. Steam is used to reduce the hydrocarbon partial pressure to vaporize lighter molecules. A quench recycle is used to cool the stripped bottoms below 360°C (680°F) to reduce coking and cracking of the hydrocarbons. 

Updated and revised ihroughom, this standard reference describes recent advances in the design of tower packings and the commercial application of packed columns such as absorption, stripping, distillation, and extraction. It reflects current changes to improve energy efficiency and reduce the environmental impact of processing operations. 

There are a number of additional modes of operating a distillation column. These include partial condenser open steam introduced at the column bottom without a reboiler enriching distillation column stripping distillation column operation with a side stream, etc. We will briefly describe each one of these in the context of equilibrium stages/ plates and constant molal overflow. 

Figure 8.1.26. (a) Enriching distillation column (b) stripping distillation column. 

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