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mol EG formed per mol EO converted

The base case configuration is a sieve tray with a 80 mm weir height, in which the liquid and vapor phases are both considered to be well mixed. The yield of EG is plotted on the x-axis and the yield of by-product diethylene glycol (DEG) is plotted on the y-axis. The performance of the base case configuration is indicated by the large black diamond. EG production is increased and DEG production is lowered when both the liquid and vapor phases are considered to be in plug flow (large black square). Increasing the weir height from 80 to 100 mm also has a beneficial effect of increasing EG yield while decreasing DEG yield. A clever choice of hardware can enhance conversion and selectivity in RD. We need to

Front view Weirview Top view

Front view Weirview Top view

Fig. 7.5 Simplified 'snapshots' of the front, 1.2 X 10~3 m3/s/m. An animation of the weir, and top views of sieve tray simulations at simulation can be viewed on our web site:

a superficial gas velocity, Uc = 0.7 m/s; weir http://ct-cr4.chem.uva.nl/sievetrayCFD. The height hw = 80 mm; liquid weir load Q_/W = arrows indicate the liquid velocity vectors

Fig. 7.5 Simplified 'snapshots' of the front, 1.2 X 10~3 m3/s/m. An animation of the weir, and top views of sieve tray simulations at simulation can be viewed on our web site:

a superficial gas velocity, Uc = 0.7 m/s; weir http://ct-cr4.chem.uva.nl/sievetrayCFD. The height hw = 80 mm; liquid weir load Q_/W = arrows indicate the liquid velocity vectors ensure plug flow of liquid, and vapor, phases on the tray and minimize the danger of liquid phase bypassing and dead zones. Such detailed information on flows is not usually available in the literature. One way to obtain this information is to use CFD simulations [8-11]. For a sieve tray of 0.3 m diameter operating at a superficial gas velocity of U = 0.7 m/s in the bubbly flow regime, CFD simulations [9] underline the chaotic behavior of the liquid and gas flows and show the existence of several recirculating liquid flow patterns, as sketched in Fig. 7.5. The liquid RTD is far removed from the plug-flow conditions desired in practice. One could envisage the installation of flow straighteners in the liquid path to suppress back-mixing. CFD simulations are invaluable aids in screening various hardware configurations because they are able to capture the circulation patterns. It is, however, essential to perform fully transient 3D simulations, which are computationally expensive.

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