Data scaleup

Manufacturing approaches for selected bioproducts of the new biotechnology impact product recovery and purification. The most prevalent bioseparations method is chromatography (qv). Thus the practical tools used to initiate scaleup of process Hquid chromatographic separations starting from a minimum amount of laboratory data are given. 

Correlations of nucleation rates with crystallizer variables have been developed for a variety of systems. Although the correlations are empirical, a mechanistic hypothesis regarding nucleation can be helpful in selecting operating variables for inclusion in the model. Two examples are (/) the effect of slurry circulation rate on nucleation has been used to develop a correlation for nucleation rate based on the tip speed of the impeller (16) and (2) the scaleup of nucleation kinetics for sodium chloride crystalliza tion provided an analysis of the role of mixing and mixer characteristics in contact nucleation (17). Pubhshed kinetic correlations have been reviewed through about 1979 (18). In a later section on population balances, simple power-law expressions are used to correlate nucleation rate data and describe the effect of nucleation on crystal size distribution. 

The constant may depend on process variables such as temperature, rate of agitation or circulation, presence of impurities, and other variables. If sufficient data are available, such quantities may be separated from the constant by adding more terms ia a power-law correlation. The term is specific to the Operating equipment and generally is not transferrable from one equipment scale to another. The system-specific constants i and j are obtainable from experimental data and may be used ia scaleup, although j may vary considerably with mixing conditions. Illustration of the use of data from a commercial crystallizer to obtain the kinetic parameters i, andy is available (61). 

Knowledge of the mechanism will allow htting experimental data to a theoretical rate expression. This will presumably be more reliable on extrapolation or scaleup than an empirical ht. 

Confounded reactors are likely to stay confounded. Data correlations can produce excellent fits and can be useful for predicting the response of the particular system on which the measurements were made to modest changes in operating conditions. They are unlikely to produce any fundamental information regarding the reaction rate, and have very limited utility in scaleup calculations. 

What models should be used, either for scaleup or to correlate pilot-plant data Section 9.1 gives the preferred models for nonisothermal reactions in packed beds. These models have a reasonable experimental basis even though... 

Small steady-state reactors are fiequently the next stage of scaleup of a process from batch scale to full commercial scale. Consequently, it is common to follow batch experiments in the laboratory with a laboratory-scale continuous-reactor process. This permits one both to improve on batch kinetic data and simultaneously to examine more properties of the reaction system that are involved in scaling it up to commercial size. Continuous processes almost by definition use much more reactants because they run continuously. One quickly goes from small bottles of reactants to barrels in switching to... 

Data gathering to support scaleup to stirred tanks at different scales... 

The design procedure used by Kosters, of Shell Oil Co., who developed this equipment, requires pilot plant measurements on the particular system of HTU and slip velocity as functions of power input. The procedure for scaleup is summarized in Table 14.5, and results of a typical design worked out by Kosters (in Lo et al., 1983, pp. 391-405) are summarized in Example 14.11. Scaleup by this method is said to be reliable in going from 64 mm dia to 4-4.5 m dia. The data of Figure 14.18 are used in this study. 

For design of a large-scale commercial extractor, the pilot-scale extractor should be of Ihe same type as that to be used on the large scale Reliable scaleup for industrial-scale extractors still depends on correlations based on extensive performance data collected from both pilot-scale and large-scale extractors covering a wide range of liquid systems. Only limited data for a few types of large commercial extractors arc available in the literature,... 

The operations of the 250 T/D pilot plant are designed to demonstrate the operability of the EDS liquefaction section and obtain the scaleup data required for design of a commercial facility. Key objectives are demonstration of unit operability,... 

One type of system scaleup which can be done with confidence is extending efficiency data from one pressure to another. The small increase of efficiency with pressure (Sec. 7.3.4) can be allowed for using the O Connell correlation (Sec. 7.2.2). Caution is required when going to high pressures (> 150 psi), as vapor recycle may reduce efficiency, and this effect is difficult to predict. 

Scaleup from Oldershaw column. One laboratory-scale device that found wide application in supplying efficiency data is the Oldershaw column (Fig. 8.13 Ref. 207). This column is available from a number of laboratory supply houses and can be constructed from glass for atmospheric operation or from metal for superatmospheric separations. Small hole diameters and small tray spacings are used. Typical column diameters are 1 to 3 in. 

Fair et al. (203) investigated scaleup of Oldershaw column data to commercial columns. Over the region of practical interest (50 to 35 percent of flood), the commercial point efficiency was either equal to or slightly higher than the Oldershaw column efficiency. Fair et al. concluded that the Oldershaw column efficiency la essentially a point efficiency measurement, and recommend this point efficiency for the design of commercial columns. A mixing model can be used to convert the point efficiency to overall column efficiency. This will enhance the commercial column efficiency. In a later paper (145), Chan and Fair include an additional correction for weir height this correction will also enhance the commercial column efficiency. A conservative approach proposed by Fair et al. is to apply the Oldershaw cal urn n effi-... 

Was the column used to derive the data of the same scale (diameter, bed heights) as will he used in the new design If not, are there any scaleup effects that should be allowed for ... 

The flow regime plays a very important role in reactor scaleup. If the data obtained in the pilot-scale reactor are to be useful for a larger-scale reactor, the flow regime in these two reactors must be the same. The flow regimes in a variety of fixed-bed operations are described in Chaps. 6 to 8. 

Experimental RTD data from real commercial reactors is needed. This type of data would be very useful in examining the applicability of macromixing models discussed here to large-scale systems. Furthermore, with the help of such data, one could evaluate the usefulness of various models for scaleup purposes, and their applicability to systems other than air and water. 

Reactors to obtain accurate intrinsic kinetic rate data which are needed for design, scaleup, and optimization purposes. In these reactors the fluid dynamics and various heat and mass-transfer resistances are either known or amenable to rigorous calculations. 

Schematic diagrams of various types of fixed-bed reactors are shown in Fig. 1 -1. The reactor thus reproduces the industrial reactors on a small scale and it can be used to obtain the required data for reactor scaleup.

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