ISSN:
0001-1541
Keywords:
Chemistry
;
Chemical Engineering
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Process Engineering, Biotechnology, Nutrition Technology
Notes:
Relationships are developed for establishing the most economic values of the major variables of a liquid-extraction process, including the concentrations of solute in recycled solvent and rejected raffinate, the solvent-to-feed ratio, and for mixer-settlers certain of the design features. Consideration is given to costs of extraction and solvent recovery, as well as to the value of unextracted solute and lost solvent. For the design of mixer settlers scale-up relationships are developed to permit prediction of the stage efficiency of a large extractor from experimental data taken on a small scale. These are expressed in terms of a scale-up index relating the relative size of the mixer with the volumetric rates of liquid flow. It is shown that the cost of multistage extractor increases with scale up in a different fashion from the stage efficiency, depending upon the scale-up index used. A detailed study of the costs for a typical case led to the development of economic scale-up indexes which, because they cover nearly a fivefold ratio of fixed to operating costs, are of fairly general utility. The common practice of scaling up with equal holding times on the large and small scale is shown to be amply safe from the point of view of stage efficiency to be realized on the large scale but usually uneconomic.Simplification of the complete system of equations permits rapid estimation of the most economic circumstances for any type of countercurrent extractor of which the cost per stage is proportional to Qg.
Additional Material:
9 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/aic.690050414
