Addition profile

Conversely, the optimization is now constrained to be at a fixed (optimized) temperature, but the chlorine addition profile optimized. Both the feed addition profile and the total chlorine feed are optimized. The optimum temperature reaches its upper bound of 150°C. Chlorine addition is 75.0 kmol and the batch cycle is 1.35 h. The resulting fractional yield of MBA from BA now reaches 97.4%. 

The final option is to allow both the chlorine addition profile and temperature profile to be varied through the batch. The optimization shows a further improvement of the objective to 99.8%. It requires 1.35 h of batch cycle time and 75.0 kmol of chlorine. The optimized profiles for reaction temperature and feed addition rate of chlorine are shown in Figure 14.5. 

The integral can be solved by Laplace transformation. With a given deactivation kinetics N (t) is then fixed at inversion of the solution of Eq. (5.85), the necessary addition profile is given by Eq. (5.86). 

This reference generated additive profiles for various test materials but did not specify the individual additives found. 

A difference Fourier map, calculated at this point, reveals an additional small electron density maximum in the tetrahedral cavity next to the partially occupied V2. Thus, it is reasonable to assume that the V2 site splits into two independent partially occupied positions with the coordinates, which distribute V atoms in a random fashion in two adjacent tetrahedral positions rather than being simply vanadium-deficient. We label these two sites as V2a (corresponding to the former V2) and V2b (corresponding to the Fourier peak). Refinement of this model slightly improves the fit. Subsequently, additional profile parameters (F, F , and sample displacement) were included in the refinement, followed by a typical procedure of refining the porosity in the Suortti approximation with fixed atomic coordinates and Ui o, and then fixing the porosity parameters for the remainder of the refinement. 

Figure 9-3 Addition rate profile for Unear (curve A) and programmed (curve B) antisoivent addition rates. The linear addition profile adds antisoivent to the batch solution linearly overtime. The programmed addition profile gradually increases the addition rate of antisoivent to the batch solution over time.

The crystallization is conducted at 55°C in a 92/8 v/v ethyl acetate/ethanol system. Table 10-2 outlines the different addition modes of reactant to demonstrate the impact of addition of reactant on the formation of nuclei. Figure 10-12 illustrates the linear and programmed (cubic) addition profiles. 

Semibatch reactive crystallization process. Maxinrization of weight mean size while minimizing coefficient of variation NSGA-n Dynamic optimization problems were solved to find the optimal feed addition profile. Sarkar et al. (2007)... 

At an industrial scale, heat removal is performed preferably under conditions of constant coolant temperature and flow-rate. Under these conditions, the rate of water addition is the only means of maintaining the reaction temperature within the desired range. To compensate for the diminished heat output as the reaction proceeds, the water addition rate can be increased accordingly. Ultimately, the coolant temperature must also be gradually increased when close to completion in order to maintain the desired working temperature. This mode of temperature control was demonstrated on a 50 L scale, and the temperature and rate of water addition profiles for this experiment are plotted in Fig. 27. Reaction completion is attained in 9 hours (ee=99%) with a potential yield of epichlorohydrin of 47% (94% of theory). These results are consistent with those predicted by the kinetic model (see Tab. 9). 

The chassis structure of the hybrid low-floor COBRA tram consists of a frame and a floor module, made of welded aluminum (hollow extrusions [3]) (Fig. 32.9). The composite sandwich roof panel is glued with elastic adhesives to the aluminum roof cant rail. All heavy aggregates are positioned on top of the composite roof panel. Due to the foam core, the loads had to be introduced by additional profiles (connected to the roof cant rail) to smoothen any local peaks. The GRP sidewall panels are joined to the aluminum pillars and the major longitudinal extrusions by long running layers of the elastic adhesive Sikaflex -254 Booster. The structural analysis of this tram vehicle proved the structural integrity of the new design for the load history specified. The stiffness of the structure has been sufficient to fulfill all the deformation criteria (Fig. 32.10). Based on these results, the preproduction series of the first six COBRA trams was produced and is in normal service operation an additional 68 trams will have followed by 2010. 

In the group of Guillot [25], Kong used combinations of surface end-group characterization techniques to reveal the influence of the monomer addition profiles on the distribution of SOa" and COO groups. 

In copolymerization, control of the copolym composiricm can be obtained when applying monomer addition profiles. These monomer addition profiles either can be based on the direct translation of on-line measurements to monomer addition steps (controlled ccxnposiritxi reactor) or the profiles can be predicted by emulsion copolymoization models on a conversion basis. The required conversion-time relation is then obtained by on-line measurements. 

Fig. 17.21 Radar-echo measurements across the Reckling Moraine at 1,000 W (Fig. 17.16) reveal that the ice is flowing across a bedrock ridge which apparently deflects basal ice to the surface where it forms a supraglacial moraine. The presence of this ridge was confirmed by two additional profiles across the Reckling Moraine. The thickness of the ice over the ridge is only about 100 m, whereas the adjacent valley is filled with ice that is more than 400 m thick (Faure and Buchanan 1987 Faure 1990c Faure et al. 1993)...

Figure 18 Zeta potential of skin, as a function of pH, in the presence of various additives. Profile for hair eontrol is ineluded. (From Refs. 12, 40.)...

Consistent with the postulated hydrophobic association in aqueous media, addition of organic solvents such as DMSO, DMF and acetone at constant polymer concentration causes a drop in Brookfield viscosity. This behavior is illustrated in Fig. 7.8 for the addition of acetone. There is no effect until about 5% by volume and then there is a dramatic 3-30 fold decrease at an acetone concentration of 15%. Similar effects are observed for the addition of urea and ionic and nonionic surfactants (Fig. 7.9). In the latter case however, the viscosity vs additive profile is more complicated. There is a sharp initial decrease followed by an increase. The nature of this increase at higher surfactant concentration is unclear at present. The sharp decrease is consistent with association of the... 

Optimal addition profile. Arzamendi etal. (1989) developed a so-called optimal monomer addition strategy. By using this method they demonstrated that within a relatively short period of time homogeneous vinyl acetate (VAc)-methyl acrylate (MA) emulsion copolymers can be prepared in spite of the large difference between the reactivity ratios. The reactor was initially charged with all of the less reactive monomer (viz., VAc) plus the amoimt of the more reactive monomer (viz., MA) needed to initially form a copolymer of the desired composition. Subsequently, the more reactive monomer (MA) was added at a computed (time variable) flow rate (optimal addition profile) in such a way as to ensure the formation of a homogeneous copolymer. 

Figure 3.6 CCDs, experimentally determined with HPLC, of three styrene/methyl acrylate emulsion copolymers, all with Fs = 0.25 and (M/W)o = 0.2 (g/g). (a) conventional batch process (3h) (b) semi-continuous, starved conditions (32 h) (c) semi-continuous, optimal addition profile (5 h). (Reproduced with permission from G.H.J. van Doremaele, Ph.D. thesis, Model Prediction, Experimental Determination, and Control of Emulsion Copolymer Microstructure, Eindhoven University of Technology, The Netherlands, 1990.)...

Even if an iterated monomer addition profile as described in the previous section, is used, deviations from the desired copolymer composition may be found in a latex production plant. These deviations may be found if disturbances show-up that are not considered in the model. A typical example is the unexpected inhibition due to changes of the inhibitor content in the monomer feedstock. 

Figure 4.15 shows the master curves necessary to produce a homogeneous BA-MMA copolymer containing 50 mol% BA and 50 mol% MMA at a temperature of 70°C. The master curves are calculated for two different monomer swelling values (constraint 2). The master curves show the amounts of monomer BA and MMA that must be added into the reactor as a function of conversion. The values at zero conversion represent the monomer that must be initially present in the reactor. The plot also shows that the addition of the less reactive monomer must end at a lower conversion than the more reactive monomer. This difference in the optimal monomer addition profiles calculated for case (a) (a limit is imposed in the free amount of BA in the particles) and case (b) (saturation limit) show that the complete addition of the monomers can be achieved at lower overall conversion (in less process time) when a higher limit is imposed in the concentration of monomer in the polymer particles. 

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