Optimization of flow rate

Optimization of Flow Rates in a Liquid-Liquid Extraction Column.448... 

EXAMPLE 12.2 OPTIMIZATION OF FLOW RATES IN A LIQUID-LIQUID EXTRACTION COLUMN... 

The optimization of flow rate is best represented graphically. Thus a plot of HETP versus flow rate will generate a graph similar to that shown in Figure 2.3. 

HPLC and FIA. This design needs careful optimization of flow rate... 

The collection medium for gases can be liquid or solid sorbents, an evacuated flask, or a cryogenic trap. Liquid collection systems take the form of bubblers which are designed to maximize the gas-liquid interface. Each design is an attempt to optimize gas flow rate and collection efficiency. Higher flow rates permit shorter sampling times. However, excessive flow rates cause the collection efficiency to drop below 100%. 

Determine the optimal time to stop the reaction for a range of flow rates. Flow do the values of ki and k2 influence this ... 

First-dimension optimization The flow rate, elution time range, and the efficiency of the first-dimension column must be carefully controlled and matched to the second-dimension column, the sample loop volume, and the sampling rate. 

Consideration should be given to the flow rate of the sample through the detection cell. Shultz and co-workers have demonstrated the wide variability in reaction kinetics between ECL reactions, and hence the influence of flow rate on ECL intensity [60], For example, the rate constants (k) of the Ru(bpy)32+ ECL reactions of oxalate, tripropylamine, and proline were calculated to be 1.482, 0.071, and 0.011/s, respectively. Maximum ECL emission was obtained at low linear velocities for slow reactions ranging up to high linear velocities for fast reactions. That is, the flow rate and flow cell volume should be optimized such that the light-emitting species produced is still resident within the flow cell, in view of the light detector, when emission occurs. 

A detector plays an important part in achieving overall performance when optimizing for very short run times with reasonable peak capacities. The detector should match the optimized LC conditions in terms of flow rate and dispersion. The electronics must accurately capture the peak form produced by the column this is most important for quantitative analyses. The data quality may be limited by the laws of physics at high speed. The amount of data produced over time can become an issue. 

Application of 2 fractional factorial design allowed the optimization of the gradient HPLC proeednie for the determination of ibnprofen, pseudoephedrine HCl, ehlor-pheniramine maleate and nipagen in symp preparation. The optimum eonditions for this determination were found to be 3 of pH, 1.5 mL/min of flow rate, 85%, 55% and 40% of buffer eompositions of steps of gradient profde. 

Fig. 8. Optimal nitrogen flow rate for variable V. Reprinted with permission from Comp. Chem. Eng., 14, No. 10, 1083-1100, S. Vasantharajan and L. T. Biegler, Simultaneous Optimization of Differential/Algebraic Systems with Error Criterion Adjustment, Copyright 1990, Pergamon Press PLC.

Facilitated transport of penicilHn-G in a SLM system using tetrabutyl ammonium hydrogen sulfate and various amines as carriers and dichloromethane, butyl acetate, etc., as the solvents has been reported [57,58]. Tertiary and secondary amines were found to be more efficient carriers in view of their easy accessibility for back extraction, the extraction being faciUtated by co-transport of a proton. The effects of flow rates, carrier concentrations, initial penicilHn-G concentration, and pH of feed and stripping phases on transport rate of penicillin-G was investigated. Under optimized pH conditions, i. e., extraction at pH 6.0-6.5 and re-extraction at pH 7.0, no decomposition of peniciUin-G occurred. The same SLM system has been applied for selective separation of penicilHn-G from a mixture containing phenyl acetic acid with a maximum separation factor of 1.8 under a liquid membrane diffusion controlled mechanism [59]. Tsikas et al. [60] studied the combined extraction of peniciUin-G and enzymatic hydrolysis of 6-aminopenicillanic acid (6-APA) in a hollow fiber carrier (Amberlite LA-2) mediated SLM system. 

Temperature and pressure are rarely optimized in HPLC, but these parameters are very important in SFC, hence can alter retention, selectivity, and resolution. Toribio et al. [149] presented the chiral separation of ketoconazole and its precursors on Chiralpak AD and Chiralcel OD CSPs. The authors also reported that alcohol modifiers provided better separation than acetonitrile. Further, Wilson [143] studied the effects of composition, pressure, temperature, and flow rate of the mobile phase on the chiral resolution of ibuprofen on a Chiralpak AD CSP. It was observed that temperature affords the greatest change in resolution, followed by pressure and composition. An increase in methanol concentration, pressure, and temperature has resulted in poor chiral resolution. At first chiral resolution increased with an increase of flow rate (up to 1.5 mL/min) but then started to decrease. Contrary to this, Biermann et al. [135] described the... 

For absorption controlled by diffusion through a gas film, it is necessary to provide a large enough interface area the interface area depends on the liquid to gas flow rate ratio, VL/VG, essentially for a defined dispersity of the absorbent. On the other hand, increasing VJV,c must lead to increased power consumption so it is important to optimize the flow rate ratio.. The experimental results on the influence of VL/VG on the sulfur-removal efficiency are shown in Fig. 7.13. To keep the conditions of atomization essentially the same, all the experiments in this set were carried out at a fixed volumetric liquid flow rate, VL while the gas flow rate, VG, for each run varies according to the required liquid to gas flow rate ratio and, simultaneously, the corresponding concentration of Ca(OH)2 was used to keep the ratio of Ca/S the same as 1.4. 

Optimal operating conditions can be maintained over a wide range of flow rates and feed compositions. The high energy density that is generated reduces the chemical reaction time. This results in a short residence time for the reactants to be converted into products. A wide range of hydrocarbons can be used for the production of synthesis gas or hydrogen, with conversion of hydrocarbons close to 100%. 

The method of coordinatewise optimization was proposed for simultaneous choice of flow rates and pressure losses on the closed redundant schemes (Merenkov and Khasilev, 1985 Merenkov et al., 1992 Sumaro-kov, 1976). According to this method motion to the minimum point of the economic functional F(x, Pbr) is performed alternately along the concave (F(x)) and convex (F(Pbr)) directions. The convex problem is solved by the dynamic programming method and the concave one reduces to calculation of flow distribution. The pressure losses in this case are optimized on the tree obtained as a result of assumed flow shutoff at the end points of some branches. The concave problem is solved on the basis of entropy... 

Optimization of Pumping Rates in the Through-Flow System... 

We adopt the input/output data-based prediction model using the subspace identification technique. To find the correlation between the inputs and outputs, we need to obtain the input and output data. On the basis of the triangle Aeoiy[6], the optimal feed flow rate ratios at steady state are calculated. Then, the pseudo random binary input signal is generated on the basis of this optimal value. Figure 1 compares the output from the identified model (dot) with that from the first principles model (solid curve). Clearly, we observe that the identified model based on the subspace identification method shows an excellent prediction performance. The variance accounted for (VAF) indices for both outputs are higher than 99%. The detailed identification procedure can be founded in the literature [3,5,9,10]. 

Packings and Flooding As pointed out above, optimized mass and heat balances have been derived from a combination of experimental results with a con uter simulation of the process. The optimized balances can be used for the layout of a production plant A multi-purpose plant should be able not only to produce samples, but also to determine scaleup parameters. The scaleup parameters depend on the type of packing and its specific flooding point The ability to measure flooding points or to test different packings is restricted mainly by the range of flow rates. 

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