Filtrate processing over

Results of test work with this filter, producing cakes of 1 mm thickness using a 3 mm clearance, have been pubUshed (33,34). The cake formed on the medium was generally stable, giving high filtration rates over long periods of time, and the precoat type cake did not blind with time. There was no evidence of any size selectivity of the process the only exception was conventional filter aids which were preferentially picked up by the rotating fluid. This... 

Belt Presses Belt presses were fiiUy described in the section on filtration. The description here is intended to cover only the parts and designs that apply expression pressure by a mechanism in adchtion to the normal compression obtained from tensioning the belts and pulling them over rollers of smaller and smaller diameters. The tension on the belt produces a squeezing pressure on the filter cake proportional to the diameter of the rollers. Normally, that static pressure is calculated as P = 2T/D, where P is the pressure (psi), T is the tension on the belts (Ib/hnear in), and D is the roller diameter. This calculation results in values about one-half as great as the measured values because it ignores pressure created by drive torque and some other forces [Laros, Advances in Filtration and Separation Technology, 7 (System Approach to Separation and Filtration Process Equipment), pp. 505-510 (1993)]. 

When the space above the suspension is subjected to compressed gas or the space under the filter plate is under a vacuum, filtration proceeds under a constant pressure differential (the pressure in the receivers is constant). The rate of filtration decreases due to an increase in the cake thickness and, consequently, flow resistance. A similar filtration process results from a pressure difference due to the hydrostatic pressure of a suspension layer of constant thickness located over the filter medium. 

For a constant pressure drop and temperature filtration process all the parameters in Equation 9, except V and x, are constant. Integrating Equation 9 over the limits of 0 to V, from 0 to x, we obtain ... 

Filtration constants K and C can be experimentally determined, from which the volume of filtrate obtained over a specified time interval (for a certain filter, at the same pressure and temperature) can be computed. If process parameters are changed, new constants K and C can be estimated from Equations 14 and 15. Equation 16 may be further simplified by denoting tg as a constant that depends on K and C ... 

In order to develop a continuous flux maintenance procedure, the present study examined the transmembrane flux values from the cross-flow filtration module with a filtration media area of 0.0198 m2 (0.213 ft2), a slurry density of approximately 0.69 g/cm3 at 200°C, 17 kg of simulated FT wax with a catalyst loading of 0.26 wt%, and a TMP between 0.68 and 1.72 bar (10-25 psig). The filtration process was run in a recycle mode, whereas clean permeate was added back to the slurry mixture, thus allowing the catalyst concentration to remain approximately constant over the course of the run (given minor adjustments for about 5 ml permeate and slurry samples collected throughout the test). 

Some mathematical models have been developed to predict the behavior of the pressure drop over the diesel particulate trap with time during the loading/regenera-tion cycles [62, 67-69], to calculate the effect of filter-medium properties on filter performance of fibrous filters [70] or to describe the flow and filtration process [71] and the regeneration process [72-75]. An illustrative example for the performance of such a pressure drop model is provided in Fig. 15.7. 

When first starting the filtration process, the vacuum will suck some of the product into the flask. The contents of the flask should then be re-filtered to ensure no product loss. The suction force is generated by a vacuum pump, which is commercially available in many styles and sizes hand driven pumps can be used as well. Note The suction force should not be too great. Placing your hand completely over the funnel until the suction grips your hand moderately indicates the proper suction. Never underestimate the power of a vacuum. 

For CMF to be deemed a successful replacement of traditional clarification methods for the main filtration process, a high beer flux is required (generally, a minimum of 100 L/(m h) is considered necessary), with power costs that do not exceed those associated with the traditional filter aids [37]. Gan [32] considered that an average flux rate of 40 kg/(m h) over 10 h of continuous filtration is of commercial interest. 

Besides validating the occurrence of ion exchange, the experimental results of Waley and Thompson also established the preference of soil toward ammonium and potassium over calcium—a phenomenon that helped explain how ion exchange plays a key role in plants uptake of nutrients from soils. In principle, the ion exchangers present in soil with varying sele-ctivities toward different ions opened a new avenue to separate dissolved species by a simple filtration process. 

Figure 11-11 shows the flowsheet of the two-filtration process with recycle of second filtration mother liquor. For the recycle process, at the beginning of the batch, the starting materials Iso and 7-chloro were charged to a reactor. The Iso charged included the recycled Iso from the previous batch and the fresh Iso. The batch was heated and aged at the desired reaction temperature. After the reaction was complete, the batch was transferred to a crystaUizer and cooled over a period of time. Both... 

The performance of membranes often decreases over time due to effects such as fouling and concentration polarization. This is seen as a decrease in flux (Figure 9.15). This performance decline is a major concern for filtration processes, but less so for gas separation processes. 

Table IV presents data from runs in which cell cultures were grown in a defined serum-free medium with relatively low total proteins. Cell-free culture supernatants were processed over a 100K dalton membrane with or without NaCl additions. Both high and low salt solutions showed some immunoglobulin in the filtrate.

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