Flow rates, variations

C. Liquid Distributor (see Figures 4-9). According to Strigle, This is the most important column internal from a process standpoint. A liquid distributor is required at all locations in the tower where an external liquid stream is introduced. High-performance distributors provide a flow rate variation per irrigation point that is a maximum of 5% of the average flow. The geometric uniformity of... 

Errors in the molecular weight data from HPSEC are usually due to improperly prepared samples, column dispersity, or flow rate variations. The sample to be analyzed should be completely dissolved in the mobile phase and filtered prior to injection onto the column. A plugged column inlet frit will invalidate results. In addition, do not load the column with excess sample. Column overloading affects the accuracy of data by broadening peaks, reducing resolution, and increasing elution volume. For best results, the concentration of the injected sample should be as low as possible while still providing adequate... 

Calibration curves for PS and PMMA are shown in Figs. 15.3-15.5. The slight differences in courses of calibration curves for PS in THF, chloroform, and toluene, as well as the curve for PMMA in THF (Fig. 15.3), can be explained by the flow rate variations for different pumping systems and by the hydrodynamic volume effects, respectively. The calibration curves for PMMA in mixed eluents THF/toluene are shown in Fig. 15.4. Three percent of THF in toluene assured a reasonable SEC elution of PMMA. However, more chloroform was needed to obtain a good SEC elution of PMMA in mixed eluent chloroform/toluene... 

Minutes/hours for example, storms affecting sewer systems, punctual discharges, river flow rate variations due to hydroelectric plants, residence time in a WWTP, etc. 

The detector was calibrated by pxm ing solutions of sodium dichromate of known absorbance through the sample port of the detector. The solutions were prepared in the carrier fluid which served as reference. The recorder response was measured as the ultimate height reached on the chart paper above the baseline when the sample fluid was switched to a sodiiam dichromate solution of known absorbance. The calibration was insensitive to flow-rate variations. 

Bly, D. D., Yau, W. W., and Stoklosa, H. J., Siphon counter techniques for minimizing molecular weight errors caused by flow-rate variation in high performance liquid exclusion chromatography, Anal. Chem., 48, 1256, 1976. 

Wall excursion with possible flow oscillation Cyclic flow regime transitions and flow rate variations... 

The Waters Model 244 liquid chromatograph Is not equipped with a thermostated oven and, therefore, operates at ambient temperature. We have observed some variations In flow rate due to laboratory temperature changes. Flow rate variations can be Illustrated by comparing the cyclic trlmer elution volume In... 

Flow rate variations cause three types of sampling errors ... 

A recycle valve was provided around the pump to enable discharge pressure regulation and flow-rate variation. This, however, combined with shearing across the individual separator level-control valves, was probably responsible for a large percentage of droplet breakup, casting some uncertainty on the effectiveness of the pump. 

By switching the cooler from stream Sh2 to ShJ the network can be made resilient (Fig. le). In all exchangers the approach temperatures exceed 10 K over the whole range of flow rate variations 1 < s 1.85 kW/K and therefore capital costs remain reasonable. The example shows that... 

Flexible refers to a process which remains feasible for every value of the uncertain variables in the uncertainty range despite desired changes to the process (e.g., supply temperature and flow rate variations due to feedstock changes). 

Figure l. Observed CFSTR flow rates during the course of the desorption experiments for selected CFSTRs. For the 30 mg/L Tween 20 CFSTR. the cubic spline interpolation of the flow rate variations is shown. 

Detector configuration arrangement of multiple detectors in series or in parallel can cause additional peak broadening, flow rate variations, back pressure variations,... 

Figure 7 shows the dependence of axial voidage profiles on solids inventory, which was first recognized by Weinstein et al. (1983), for system FCC/air (pp = 1,450 kg/m3, dp = 59 /im). Two kinds of voidage profile curves are shown. The curves for / = 15, 20 kg in Fig. 7a and / = 15, 20, 22 kg in Fig. 7b are S-shaped, with the co-existence of two regions, and transition occurring inside the unit, while solids can be fed at the bottom of the bed at saturation flow rates. Variation of solids inventory / does not result in any change of... 

The coated wafer was placed in a petri dish and enough tetrahydrofuran was added to completely cover the wafer. The tetrahydrofuran dissolved the MP2400 resist film and the resulting solution was collected in a 5 cc volumetric flask and brought to the mark with additional solvent. Prior to the solution addition, a known constant volume of benzene solution was pipetted into the volumetric flask. The benzene serves two purposes first it acts as a marker to correct for flow rate variations and secondly its calculated area serves to normalize injection variations. 

In the field of flow rate variations defined in this way, i.e., outside the area of Newtonian behaviour and the transition zone between Newtonian and power law behavior, Kc and n may also be determined from the flow curves by comparing relations (6) and (7) (cf Fig. 3c). 

Our results show that the Varicol and the PowerFeed operations improve the performance of the SMB process, particularly when the total number of columns is small and the separations are difficult. The optimal design of the Varicol and PowerFeed processes can be replaced by the optimal design of the corresponding SMB process given by the equilibrium theory, followed by the search of the optimal ports switching and flow rates variation schemes within the switching period, respectively. 

Membrane-assisted solvent extraction processes have known an increasing number of applications in the last decades [1 ]. This technique not only overcomes the limitations of conventional liquid extraction, such as flooding, intimate mixing, limitations on phase flow rate variations, and requirement of density difference but also provides a large surface area of mass transfer per volume of contactor [5]. Excellent reviews of the technology and its applications were presented by Ho and Sirkar in 1992 [6], and by Gabelman and Hwang [7]. 

Individual mass-transfer coefficients of solute species in the feed, carrier, and strip interfacial boundary layers are determined experimentally by feed, carrier, and strip flow rate variations, using Eq. (20). 

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