Batch flux plot

Figure 33 Determination of interface and layer velocities from a batch flux plot...

For the batch flux plot shown in Figure 3W3.1, the sediment has a solids concentration of... 

Using this information we can plot the concentration profile in the test vessel 50 min after the start of the test. A sketch of the profile is shown in Figure 3W3.3. The shape of the concentration profile within the variable concentration zone may be determined by the following method. Recalling that the slope of the batch flux plot (Figure 3W3.1) at a value of suspension concentration C is the velocity of a layer of suspension of that concentration, we find the slope at two or more values of concentration and then determine the positions of these layers after 50 min ... 

Lines of slope F/A, L/A and —V/A drawn on the flux plot represent the fluxes in the feed, underflow and overflow, respectively (Figure 3W4.2). The total flux plot for the section below the feed point is found by adding the batch flux plot to the underflow flux line. The total flux plot for the section above the feed point is found by adding the batch... 

Use the batch flux plot in Figure 3E9.1 to answer the following questions. (Note that the sediment concentration is 0.44 volume fraction.)... 

The batch and continuous flux plots suppUed in Kgure 3E11.1 are for a thickener of area 200 handling a feed rate of 0.04 m /s and an underflow rate of 0.025 m /s. 

If a tangent is drawn from the point on the abscissa corresponding to the required underflow concentration C , it will meet the if curve at a concentration value CL at which fT has the minimum value (A/v. and will intersect the ordinate axis at a value equal to irTL. The construction is dependent on the fact that the slopes of the tangent and of the iru line are equal and opposite ( uu). Thus, in order to determine both Cl and (An, it is not necessary to plot the total-flux curve (ibatch sedimentation (if ) curve. The value of (A/ /, determined in this way is then inserted in equation 5.46 to obtain the required area A. 

Performance of a specific membrane with a particular feed is typically determined in a laboratory experiment. A heated quantity of feed is run over the membrane in a batch pervaporation test, and samples of feed and permeate are taken periodically and analyzed. Permeate rate is also measured. The temperature of the circulating liquid is thermostatically controlled and the permeate pressure is kept low, perhaps 5-lOmbar. Overall flux rates for permeating and nonpermeating components are determined by mass balance and plotted together with permeate composition against the feed composition. 

Between 1 and 4 grams of catalysts can be made in a batch using this set up. The amoimt of catalyst prepared is a function of the density of the support material, how well it tumbles, and volume of the SS cup. Metal loading is controlled by varying the deposition time, amount of support and the deposition rate. Calibration plots for each set of samples can be constructed in order to accurately control metal loadings. Typically loadings can be controlled to 0.05 wt%. Tlrere is some catalyst metal that does not land on the support material. The produced flux spreads out and deposits on the SS cups as well as the surrounding area. This excess material is collected and can be recycled. 

The curve shown in Figure 2.32 is a standard flux vs. concentration plot and holds true for almost all UF/MF cases. A slight variation of the plot for batch UF of a protein solution is shown in Figure 2.33 [50]. In this plot, gel polarisation seems to be a two-step process involving build-up and closing at low concentrations followed by compaction of the sublayer. The test run used three membranes DP06, an isotropic microfilter with a pore size of 6000 A PM-10, a polysulphone UF membrane with a MWCO = 10,000 Da and PM-30, a polysulphone UF membrane with a MWCO = 30,000 Da. The pure water... 

---