Membranes Perforated plates

Fig. 35.—Assembled osmometer of Weissberg and Hanks." (1) Solution and reference capillary (2) solution cell (3) osmometer base (4) pressure ring (5) perforated plate (perforations not shown) (6) semipermeable membrane (7) mercury seal (8) solvent container (9) solvent level (10) cover plate ...

A majority of membrane cells operate with the membrane resting on the anode. It is conceivable that the structure of the anode is an important design parameter. Asahi Chemical Industry claims to have optimized the structure of the anode by the use of a perforated plate. However, it is theoretically possible to design... 

Control of the back-pressure level required for efllbctive back-flushing has bear claimed with the use of flat perforated plate elements in the Cricket filter [Filtration and Separation, Sep/Oct., 1991]. Automatic, semicontinuous cleaning of tubular candle filters can also be realised by momentary reversal of the filtrate flow a resulting bump is defivered to the cake, which is dModged and Ds to the cone-shaped bottom of the unit, Bgure 11.53. The effectiveness of these filters is inproved by the use of filter media whkh can handle veiy dilute suspensions of fine (< 0.5 pm) particles, e.g. PIPE membranes). 

Almost all countercurrent extraction devices utilize dispersion of one immiscible phase as drops in another immiscible phase we will provide a brief introduction here. At the end, we will introduce porous hollow fiber membrane based nondispersive countercurrent solvent extraction devices. The dispersive devices may involve continuous agitation or no agitation at all. Dispersive devices without any agitation as such are of three types spray towers packed towers perforated plate towers. Spray towers were illustrated in Figure 8.1.2(b). 

In the CFD modelling of membrane filtration process, membranes are usually modelled as a porous wall while the flow within a membrane is usually solved using both Navier-Stokes and Darqr equations (Ghidossi et al, 2006). A porous media model is widely used for determining the pressure loss during flow through packed beds, filter papers, perforated plates, flow distributors and tube banks (ANSYS, 2010). A momentum source term is added to the governing momentum equations, which creates a pressure drop that is proportional to the fluid velocity ... 

Alternatively, the film is placed between two perforated lead plates and grafted with monomer M by the mutual method. After grafting, the film is now placed between the two perforated lead plates taking precautions that only the ungrafted portions of the grafted film are exposed to gamma radiations in the presence of monomer M2. Schematically, the preparation of the mosaic membrane is shown in Fig. 2. 

In such an osmometer the lateral walls on the depth of the half cells are made up of perforated brass plates the width and the depth of each groove in the plate are 1.5 mm and the distance between two adjacent groove is also 1.5 mm. The diameter of osmometer cell is 11.5 cm. The semi-permeable membrane is clamped between the two half-cells. The solution is placed in the glass-tube having a needle-type stopcock and is fitted with pure solvent. The volume of the osmometer cell is about 7 ml. The assembled osmometer is put in a double-walled air thermometer. The temperature fluctuations in the thermostate are 0.05°C. 

More popular and widely used these days are relatively small and simple osmometers based on the Zimm-Meyerson design (Zimm 1946), in which two membranes are held against a glass solution cell by means of perforated metal plates, as shown in figure below. 

The lateral surfaces of the osmometer cell are carefully ground with fine abrasive powders. It is very important that the wall surfaces of the cell be parallel. The semi-permeable membranes are applied to these surfaces and are tightly clamped with two ground brass plates, perforated with 1 -2 mm holes. The reference capillary shows the level of the solvent for this reason the inner diameters of two capillaries should be equal. 

Zhang, Advani, and Prasad [51,52] also used microfabrication techniques in order to develop a thin, perforated copper foil and use it as a cathode DL in a PEMLC. In addition to the metal DL, an "enhancement" layer was used that consisted of a porous material locafed befween the perforated copper foil and fhe LF plate (CLP was used in fhis study). This layer improved the overall short-term performance and wafer managemenf of fhe cell. Flowever, the authors did not discuss any possible long-term issues related to contaminahon of the membrane due to the use of a copper DL. 

Cell construction is mainly confined to two types, using either pocket plate electrodes (vented cells) or sintered , bonded or fibre plate electrodes (vented and sealed cells). In the former, the active materials are retained within pockets of finely perforated nickel-plated sheet steel which are interlocked to form a plate. Positive and negative plates are then interleaved with insulating spacers placed between them. In sintered plate electrodes, a porous sintered nickel mass is formed and the active materials are distributed within the pores. In sintered plate vented cells, cellulose or other membrane materials are used in combination with a woven nylon separator. In sealed or recombining cells, special nylon separators are used which permit rapid oxygen diffusion through the electrolyte layer. 

A special module design that is a hybrid between a plate and a spiral-wound module has been developed by the research institute GKSS in Germany. Here, two membrane sheets are welded together (by heat or ultrasonic welding) to a sandwich structure with a permeate spacer between the two membranes. A multitude of these sandwiches, each with a central hole, is arranged on a central perforated tube that removes the permeate. Each membrane sandwich is sealed from the feed to the permeate side at the central perforated permeate... 

Gas distributors used in BCs include (i) sintered, perforated, or porous plates (ii) membrane or ring-type distributors (iii) arm spargers or (iv) single-orifice nozzles. The sintered plate (Figure 7.12a), which is usually made out of glass... 

The principle discussed above has been used to develop an electronically adjustable miao chemostat valve allowing feedback control to keep constant concentration of certain species in solution. " The chemostat consists of silicon-based upper and bottom plates as well as a circuit card for the elertric connection to the PC-controlled power supply. The upper plate carries a platinum temperature sensor and contains a hydrogel chamber ((600 x 600 x SSOjpm ), which is covered by a perforated membrane. The bottom plate has similar con-stmction with an integrated platinrrm heating element (Figure 36(a)). ... 

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