Filtrate motion

Filtration frequently is accompanied by hindered or free gravitational sedimentation of solid particles. The directions of action of gravity force and filtrate motion may be cocurrent, countercurrent or cross current, depending on the orientation of the... 

Figure 1. Direction of gravity force action and filtrate motion in filters A-cocurrent B-countercurrent C-crosscurrent solid arrow-direction of gravity force action dashed arrow- direction of filtrate motion 1-filter plate 2-cake 3-sludge 4-filtrate 5-clear liquid.

In an attempt to organize the almost overwhelming number of different types of filtration equipment, two classification schemes have evolved for continuous operations. The first scheme is based on operating pressure differentials and is provided in Table 1. The second scheme is based on the relative difference between gravity force and filtrate motion. Three orientations are possible forces acting in... 

Cocurrent or top-feed filters employ flat and cylindrical filtering media. In flat designs, the angle between the directions of gravity force and filtrate motion is 0°, but... 

Lineal diffusion and undiffusion examples. For simplicity, consider the fresh-to-saline water invasion problem, where mudcake forms and grows at the inlet entrance. At first, mud filtrate motions are extremely rapid, and fluid movements dominate the convection-diffusion process. However, as mudcake forms, the influx of filtrate decreases rapidly with time, and eventually, diffusion dominates the dynamics. For simplicity, we first study lineal flows where the effects of radial geometric spreading are unimportant. In our examples, because fluid convection is negligible, we consider K 5 C/5x = < ) 5C/5t. For numerical purposes, we fix the left-side (x = 1) concentration at C = 10%, while the right (x = 11) is held at C = 90%. For visual clarity, all concentrations to the left side of X = 6 are initially 10%, while those values to the right are 90%. 

For the HCI salt Do exactly as above except use 6N Hydrochloric Acid. 6N HCI may be produced by diluting 60.4mL of "Muriatic Acid" to lOOmL with distilled water. Evaporate the bubbler solution to dryness then add 15ml of water, lOmL 10% NaOH soln. and heat gently to a boil with constant motion until dense white fumes appear. This will remove the Ammonium Chloride. Remove from heat while stirring as it cools down. Pulverize the dry residue, then reflux with absolute Ethanol for several minutes. Filter the refluxed soln. on a heated Buchner or Hirsch funnel, then distill the alcohol off the filtrate until crystals just begin to form. Allow the soln. to cool naturally to room temperature, then cool further in an ice bath. Filter the solution on a chilled Buchner funnel with suction. The yield of Meth iamine Hydrochloride should be around 55% of the theoretical. 

Diffusional interception or Brownian motion, ie, the movement of particles resulting from molecular collisions, increases the probability of particles impacting the filter surface. Diffusional interception also plays a minor role in Hquid filtration. The nature of Hquid flow is to reduce lateral movement of particles away from the fluid flow lines. 

In reverse osmosis membranes, the pores are so smaH, in the range 0.5— 2 nm in diameter, that they ate within the range of the thermal motion of the polymer chains. The most widely accepted theory of reverse osmosis transport considers the membrane to have no permanent pores at aH. Reverse osmosis membranes are used to separate dissolved microsolutes, such as salt, from water. The principal appHcation of reverse osmosis is the production of drinking water from brackish groundwater or seawater. Figure 25 shows the range of appHcabHity of reverse osmosis, ultrafiltration, microfiltration, and conventional filtration. 

Diffusion filtration is another contributor to the process of sand filtration. Diffusion in this case is that of Brownian motion obtained by thermal agitation forces. This compliments the mechanism in sand filtration. Diffusion increases the contact probability between the particles themselves as well as between the latter and the filter mass. This effect occurs both in water in motion and in stagnant water, and is quite important in the mechanisms of agglomeration of particles (e.g., flocculation). 

A circulating tank is recommended, the motion being required to prevent skinning, creaming and sedimentation. Screening or filtration is also provided to retain air bubbles, and any coagulum. The tank contents need to be maintained at a constant temperature and the tank is equipped with a lid to prevent evaporation of water when not in use. 

In-line extrusion, 19 543 In-line filtration, 15 827 Inline motionless mixers, 16 711-716 In-motion checkweighers, 26 245 Inner-Helmholtz plane (IHP), 3 419 Inner transition-metal perchlorates, 18 278 Inner tubes, butyl rubber for, 4 434, 453 Innohep, 4 95t 5 175... 

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