Packed columns, flow simulation

The design of simulated moving bed chromatography and its application to the separation of cycloheptanone and cyclopentanone as test substances to validate the system for subsequent chiral chromatography has been described.27 Briefly, eight silica-packed columns were hooked up in series to form a cyclic flow path. On the first pair, preliminary separation of the components was performed, with the less-retained raffinate being directed to waste. Following the second pair of columns, eluent was added. After the... 

However, by examining the adsorption behavior of polypeptides and proteins with comparable porous and nonporous particles in finite baths, packed columns and expanded or fluidized beds, an iterative simulation approach based on the heuristic principles described earlier and along the lines of the flow diagram shown in Fig. 32 can be developed, leading ultimately to the implementation of useful scale-up criteria. Along the way, computer simulations, generated from the analysis of the concentration-time... 

Similarly, when values of a, kija, and k(/i are known for the packed column, the variations in and k can be determined as functions of the respective flow rates and Mg, as discussed in Section IV,A. Various stirring speeds for each phase in the laboratory model can then be related to the phase flow rates (in the packed column) which have, respectively, identical ki and kc, as outlined in Fig. 34. Thus pairs of values ofi/ and Uq are simulated by each couple Nl and Nq. 

Yin et al. (2000) developed a computational model to simulate flow and mass transfer in randomly packed distillation columns. It is necessary to develop appropriate models for interphase drag and dispersion coefficients. The general approach is to represent the overall pressure drop for gas-liquid flows in a packed column in two parts, namely wet and dry ... 

Closure models, similar to those used by Yin et al. (2000), can also be used to simulate flows in trickle bed reactors. It must, however, be noted that in a packed column used for separations, packing element size is around 25 mm, while in trickle bed reactors, the particle sizes are typically in the range 0.5 to 6 mm. For large... 

The predicted correction term is approximately three-fold less than would be required to adjust the experimental values to their value at zero flew rate. This difference is likely due to the range of polymer thickness in packed columns rather than the homogeneous coverage used in the simulation or for capillary columns. However, the first moment yields Z values that are in excellent agreement with Zp values calculated at zero flow rate Table V. 

For the purposes of simulating a packed column the packing was divided into a number of sections each of which is modeled as a nonequilibrium stage as discussed above. The C4 splitter was modeled using 150 nonequilibrium sections, an equilibrium reboiler and a total condenser. The bottom product rate in molar units and the reflux ratio were fixed at the values observed in the plant tests. Additional specifications included the component feed flows and the column pressures. 

The laboratory column is filled (loose packed) with the test material and distilled water is pumped through the column to simulate rain or runoff percolation through the highway subsurface (flow rates of 5-50 cm/day) The contaminants are leached from the test material into the water under laminar flow conditions... 

One feature which must be retained is the same mode of operation (i.e. countercurrent in our case) thus for packed column simulation one has to think in terms of the liquid running down over some kind of surface, and gas flowing upwards. If the model has also the same flow patterns, that is plug flow of both phases it is easy to show that (69) ... 

The operation of gas absorption is mostly countercurrent, that is, the gas entering to the bottom of the column and the liquid flowing down from the top. There are two usual kinds of equipment for absorption packed column and tray column. The former is most frequently used in industries, and thus, it will be the object of simulation in this chapter. 

Ergun S (1952) Fluid flow through packed columns. Chem Eng Prog 48(2) 89-94 Himmelblau DM, Bischoff KB (1968) Process antilysis and simulation deterministic systems. Wiley, New York... 

To determine the influence of the differing of LJV flow ratios on the mass transfer efficiency of the packed column using a process simulator, the packed bed column can be subdivided into several parallel bed sections [149]. The mass transfer efficiency of these sections can be calculated according to the number of theoretical stages model. 

CO2 is absorbed into propylene carbonate in a packed column. The inlet gas stream is 20 mol% CO2 and 80 mol% methane. The gas stream flows at a rate of 7200 mVh and the column operates at 60°C and 60 atm. The inlet solvent flow is 2000 kmol/h. Use available software simulators to determine the concentration of CO2 (mol%) in the exit gas stream, the column height (m), and the column diameter (m). Compare simulating results to verify hand calculations. The column consists of 1 1/2 in. ceramic Intalox saddles packing material. The carbon dioxide in the exit stream should not exceed 0.4 mol%. Assume 60% flooding. 

Computational fluid dynamics (CFD) is rapidly becoming a standard tool for the analysis of chemically reacting flows. For single-phase reactors, such as stirred tanks and empty tubes, it is already well-established. For multiphase reactors such as fixed beds, bubble columns, trickle beds and fluidized beds, its use is relatively new, and methods are still under development. The aim of this chapter is to present the application of CFD to the simulation of three-dimensional interstitial flow in packed tubes, with and without catalytic reaction. Although the use of... 

The results described in the above sections were obtained in batch studies, which generally run for less than one day. Long-term effects of water quality on catalyst activity are better observed through continuous flow columns which can operate for months or years. These column experiments generally use packed bed reactors (as in the field) and provide better simulations of field conditions. However, because the Pd technology is relatively new, few column studies have been conducted thus far results of published studies are discussed in the following section in more detail. Note that for both the column and field studies, the most relevant parameters are residence time, conversion data and pore volumes treated. The residence... 

The proposed modeling approach has been validated for distillation of non-reactive mixtures. For this purpose, the use is made of the total reflux distillation data for the binary mixture chlorobenzene/ethylbenzene (CB/EB) and ternary mixture methanol/acetonitrile/water (MEOH/ACN/WATER) obtained by Pelkonen (1997) as well as for the ternary mixture methanol/ethanol/water (MeOH/EtOH/WATER) measured by Mori et al. (2006). The experiments of Pelkonen (1997) were carried out in a column of 100 mm diameter, equipped with Montz-Pak A3-500 structured packing. The measured concentrations, temperature and flow rates at the condenser outlet are used as input values for simulations. 

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