Short-cut flow

In a real stirred tank with bypassing or short-cut flow (Fig. 3.22), highly concentrated tracer comes out early, and the residence time distribution depends on the fraction a of the flow in the bypass (Fig. 3.23). The tailing of the response curve is caused by the perfect mixing in the main part of the tank. 

In the dialyzed batch start-up phase and the subsequent continuous operation a substantial increase in viable cell density and monoclonal antibody (MAb) titer was observed compared to a conventional suspension culture. The raw data, profiles of the viable cell density, viability and monoclonal antibody titer during the batch start-up and the continuous operation with a dialysis flow rate of 5 L/d are shown in Figures 17.6 and 17.7. The raw data are also available in tabular form in the corresponding input file for the FORTRAN program on data smoothing for short cut methods provided with the enclosed CD. 

Appendix 2 is an example of the way in which the transfer function of a flow-mixing system may be used to predict the conversion of reactant which will be achieved in that system when a reaction with first-order kinetics is occurring. This short-cut route is used extensively later in this chapter. 

Short Cut Approaches. In most normal chemical processes we are concerned with the same sets of intentions in pipe-lines (flow, pressure, temperature, composition, viscosity) and it is possible to come up with a ready made list of common deviations. This is easier than returning each time to first principles - but it should always be borne in mind that for unconventional processes this approach could miss important deviations. 

Model column B2 in Figure 6.8 using a short-cut, DSTWU block. The inlet stream has a temperature of 138.7 I-, pressure of 51 psia, and molar flow rates as shown in Table 6.6. 

Generalized function mostly unit operations like continuous stirred tank reactor or plug flow reactor for react and distillation column or evaporator for separate" and also new combined operations assumptions are necessary due to lack of some data in advance calculations with linear mass- and energy balances short-cut methods ... 

Additionally, the history of 5 O or 5D from the ice core can be used as a short cut to interpreting the borehole-temperature record (Paterson and Clarke 1978 Cuffey et al. 1992, 1994, 1995 Johnsen et al. 1995, Cuffey and Clow 1997 Johnsen et al. 1997 also see Beltrami and Taylor 1995). The records of ice from GISP2 and GRIP were used for central Greenland. A provisional relation between the of ice formed from accumulated snow and the surface temperature translates the record of the ice core into a provisional surface-temperature history, which is used to drive a time-dependent heat- and ice-flow model to predict modern temperature versus depth in the ice sheet. The provisional relation between of ice and temperature is then adjusted to optimize... 

Equipment specifications were prepared and illustrated in Chap. 4. Table 6-22 could thus be worked out, using individual equipment cost estimates from this book and others. The installed cost on a 1958 basis for the process equipment alone was 216,570. Table 6-24 was next prepared from figures available from the process flow sheet and other reasonable economic facts as discussed in here. Note that short-cut methods were employed where possible since only comparative economies were desired for this type of profitability analysis. Results show that a crude BHC plant at the production level recommended is unprofitable and definitely should not be considered further. 

Froment et al. [5,6] proposed a short-cut method for the first estimate of E, which turned out to be extremely efficient. Consider two experiments carried out in an isobaric flow reactor, one at a reference temperature T the other at the reference temperature, T2 and let the conditions be such that the temperature difference AT = T, — Tj is the same over the whole length of the reactor. The reaction taking place is homogeneous and of the type A B. If the feed rates are adjusted so that equal conversions are obtained then the conversion x or the pjt versus V... 

The inside diameter of the vortex finder is also often used to control the capacity and cut size. This is done by using the above-mentioned replaceable cyclone tops or by inserting different sized nozzles into the vortex finder. The shape of the vortex finder is not subject to much variation the only significant feature is the occasional use of skirts or discs at the bottom edge to counter the short circuit flow down the outside of the vortex finder. This is relatively rare, however, as the benefit is doubtfid and possibly not worthwhile in view of the manufacturing or casting complications. 

This stronger convection loops that are calculated with the hybrid model are not only quantitative in nature, but they also lead to a short-eut flow. Sueh short-cuts are mostly hard to detect from velocity plots or animations. But the traeing of many passive... 

Flow, H., Short Cut F itnafibn of Welded Prtnies, Vessels, Chem. January, 1948, p. 122. 

Construction of guidance bunds in the pond in order to increase the retention time of the discharge water in the pond (prevent short cuts for the flow). Such bunds will, however, also increase the flow velocity. It is therefore important to optimize such arrangements. 

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