EXPERIMENTAL MEASUREMENT OF COLUMN PROFILES

To address this concern, one needs to have some sort of experimental procedure that allows one to measure column profiles at finite reflux. One could decide to erect a pilot scale distillation column to do this, but this has the drawback that it may be difficult to start-up and control, potentially wasting valuable engineering time without getting the needed insight, not to mention the huge costs involved. In 

Understanding Distillation Using Column Profile Maps, First Edition. Daniel Beneke, Mark Peters, David Glasser, and Diane Hildebrandt. 

In this chapter we introduce techniques that modify the batch experiment, in order to allow one to assimilate information regarding a finite reflux column. Numerous papers from the COMPS group have been published on this topic for both rectifying and stripping CSs, and have been shown to be extremely useful in validating the theoretical node-shifting predicted through CPMs, as well as to compare different thermodynamic models at finite reflux [1 6]. 

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Modise, T., et al. Experimental measurement of the saddle node region in a distillation column profile map by using a batch apparatus. Chemical Engineering Research and Design, 2007, 85(1) 24 30. 

Figure 4.17 Profiles of (a) Fe(II), (b) Fe(III) and (c) pH in columns of reduced soil exposed to O2 at one end for different times. Points are experimentally measured lines are predicted using the model described in the text with independently estimated parameter values (Kirk and Solivas, 1994). Reproduced by permission of Blackwell Publishing...

As confirmed by the experimental studies, the border profile corresponds to the cylindrical model only at the final stage of the drainage process when the capillary pressure in borders is close to the equilibrium value. That is why Eq. (5.37) can be used to calculate Cexp reached at the final drainage stage. However, it must be kept in mind that the pressure should be measured with a micromanometer at the foam column top. 

The available data were correlated by Ueyama and Miyauchi (U5), who found that the normalized velocity profile Eq. (3-18) represents the data reasonably well. Figure 28 illustrates the experimentally measured velocity profile of water containing bubbles from a single-nozzle gas-distributor (Y2). The bubble column was 25 cm in diameter operating in the recirculation flow regime at a superficial gas velocity Uq of 5.2 cm/sec. Estimated values of Mo = 45 cm/sec and mw = 26 cm/sec, arrived at by trial, give the best fit of the normalized profile data, and Eq. (3-18) provides a reasonable approximation. 

Results from oceanic depth profile measurements of flavins In the Tongue of Ocean, Figure 8, Indicate that during the afternoon, RF Is at relatively low concentrations In the upper 25 meters, which Is In agreement with the diurnal study. In the deeper water (> 300 m), the only detectable flavin Is RF suggesting that LC and LF are solely derived from photochemical processes, not microbial processes. In addition, the profiles also suggest that lumlchrome is more stable than lumlflavln In the water column, as lumlchrome Is advected to greater depths, which supports our preliminary experimental results on flavin stabilities. 

Experimental confirmation of MSS in RD was provided by Thiel et al. [23] and by Rapmund et al. [24]. Mohl et al. [1] used a pilot scale column to produce MTBE and TAME. MSS were found experimentally when the column was used to produce TAME, but not in the MTBE process. The measured steady state temperature profiles for the low and high steady states for the TAME process are shown in... 

We have developed a non equilibrium model for multi component reactive separation techniques. This model is solved numerically by a sure and stable strategy. The originalities of this model are the Maxwell Stefan formulation which is solved in this complete formulation and the absence of restrictive assumptions concerning the reaction. To validate the model, an experimental pilot has been developed. It is a part of column where inlet flux are controlled, and local accurate temperatures and compositions profiles are measured. For each experiments, which concern the production of methyl acetate, the results of steady state simulation are in good agreement with the experimental data and demonstrate the importance to take into account the reaction in the diffiisionnal layer. So, the non equilibrium model seems to be a well adapted toll for the simulation, design and optimisation of reactive distillation. 

Reprinted with permission from Ind.Eng. Chem Fundamentals,14> 75-91(1975). Copyright 1975 American Chemical Society, profiles in the bed coupled with hydrodynamic measurements (38,39), selectivity determinations coupled with careful kinetic characterization (36,37), or unsteady state tracer measurements in columns of different scale (40). A comparison between experimental concentration profiles determined by Chavarie and Grace (38) and the three-phase (i.e. bubble, cloud and emulsion) (20) and two phase (19) bubbling bed models appears in Figure 7. 

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