Design extraction equipment

Proprietary Extractors. Manufacturers or proprietary design extraction equipment (such as the Podbielniak Centrifugal Extractor or the RTL (raining bucket) Contactor) provide catalogs listing the relative capacities of the various sizes of equipment which are offered. Pilot equipment is usually available for determining extraction performance, and the manufacturer utilizes both the pilot data and experience with similar systems to provide assured commercial designs. 

The kfr here is for use with a driving force expressed as Aca. To obtain a suitaUe fi>r use with Axa, the right-hand side of Eq. (7.1-31) must be multiplied by (plM) for the disperse phase between I and 2. Equation (7.i-3I) is used in the design extraction equipment such as spn colnmns, perforated plate... 

The other common objective for calculating the number of countercurrent theoretical stages (or mass-transfer units) is to evaluate the performance of hquid-liquid extraction test equipment in a pilot plant or to evaluate production equipment in an industrial plant. Most liq-uid-hquid extraction equipment in common use can oe designed to achieve the equivalent of 1 to 8 theoretical countercurrent stages, with some designed to achieve 10 to 12 stages. 

The design procedure for extracting equipment requires the evaluation of the following ... 

During recent years pilot scale equipment, smaller than the prototype pilot plants described and capable of operating with exceedingly high efficiency, has been designed. Such equipment as the York-Scheibel solvent extraction tower and the Podbielniak countercurrent centrifugal mixer and extractor are typical. Data from this equipment may be correlated with commercial performance. 

SOLVENT extraction (liquid-liquid extraction) is the separation and/or concentration of the components of a solution by distribution between two immiscible liquid phases. A particularly valuable feature is its power to separate mixtures into components according to their chemical type. Solvent extraction is widely used in the chemical industry. Its applications range from hydrometallurgy, e.g., reprocessing of spent nuclear fuel, to fertilizer manufacture and from petrochemicals to pharmaceutical products. Important factors in industrial extraction are the selection of an appropriate solvent and the design of equipment most suited to the process requirements. 

T. Misek, General Hydrodynamic Design Basis for Columns, in Hquid-Liquid Extraction Equipment,... 

It was necessary, because of economic restraints, to locate the americium extraction battery in the same canyon as the mainline PRF TBP extraction equipment. Compromises in americium extraction equipment design and hydraulics were mandated to accommodate the americium extraction system in this existing facility. In particular, all the columns had to be shortened from the optimum heights recommended by the pilot plant studies. The hydraulics of the installed system were such that the organic flowrate to the extraction column (WE-1 Column) was inadequate with the result that the extraction factor was too low to permit quantitative extraction of all the 21tlAm. Furthermore, the combination of a short extraction column and a 1-inch air pulse leg sometimes led to a hydraulic upset whereby the entire column contents were lost recovery from such hydraulic upsets required an hour or more. 

Pratt, H. R. C., and Stevens, G. W. (1992). Selection, design, pilot-testing, and scale-up of extraction equipment. In Science and Practice of Liquid-Liquid Extraction (J. D. Thornton, ed.), Vol. 1, pp. 492-589. Oxford University Press, New York. 

At the heart of a leaching plant design at any level—conceptual, preliminary, firm engineering, or whatever—is unit-operations and process design of the extraction unit or line. The major aspects that are particular for the leaching operation are the selection of process and operating conditions and the sizing of the extraction equipment. 

In the process industries, material balances assist in the planning for process design, in the economic evaluation of proposed and existing processes, in process control, and in process optimization. For example, in the extraction of soybean oil from soybeans, you could calculate the amount of solvent required per ton of soybeans or the time needed to fill up the filter press, and use this information in the design of equipment or in the evaluation of the economics of the process. All sorts of raw materials can be used to produce the same end product, and quite a few different types of processing can achieve the same end result, so that case studies (simulations) of the processes can assist materially in the financial decisions that must be made. 

Information on the system design Draw off vapours directly at the point of generation and exhaust from the work area. In the case of regular work, provide bench-mounted extraction equipment. 

Identify useful equipment options for liquid-liquid contacting and liquid-liquid phase separation, estimate approximate equipment size, and outline preliminary design specifications. (See Extractor Selection under Liquid-Liquid Extraction Equipment. ) Where appropriate, consult with equipment vendors. Using small-scale experiments, determine whether sludgelike materials are likely to accumulate at the liquid-liquid interface (called formation of a rag layer). If so, it will be important to identify equipment options that can tolerate accumulation of a rag layer and allow the rag to be drained or otherwise purged periodically. 

Because the extraction factor is a dimensionless variable, its value should be independent of the units used in Eq. (15-11), as long as they are consistently applied. Engineering calculations often are carried out by using mole fraction, mass fraction, or mass ratio units (Bancroft coordinates). The flow rates S and F then need to be expressed in terms of total molar flow rates, total mass flow rates, or solute-free mass flow rates, respectively. In the design of extraction equipment, volume-based units often are used. Then the appropriate concentration units are mass or mole per unit volume, and flow rates are expressed in terms of the volumetric flow rate of each phase. 

In the design of extraction equipment with complex flows, mass-transfer coefficients are determined by experiment and then correlated as a function of molecular diffusivity and system properties. The available theories provide an approximate framework for the data. The correlation constants vary depending upon the type of equipment and operating conditions. In most cases, the dominant mass-transfer resistance resides in the feed (raffinate) phase, since... 

The use of process simulation software for process design is discussed by Seider, Seader, and Lewin [Product and Process Design Principles Synthesis, Analysis, and Evaluation, 2d ed. (Wiley, 2004)] and by Turton et al. [Analysis, Synthesis, and Design of Chemical Processes, 2d ed. (Prentice-Hall, 2002)]. Various computational procedures for extraction simulation are discussed by Steiner [Chap. 6 in Liquid-Liquid Extraction Equipment, Godfrey and Slater, eds. (Wiley, 1994)]. In addition, a number of authors have developed specialized methods of analysis. For example, Sanpui, Singh, and Khanna [AlChE J., 50(2), pp. 368-381 (2004)] outline a computer-based approach to rate-based, nonisothermal modeling of extraction processes. Harjo,... 

---