Clogging resistance

With internally unstable soils, the decision has to be made if the migrating fines should be retained or are allowed to pass. Retaining fine particles may lead to an increase in water pressure on the filter. Passing should be allowed only if this process does not affect the stability of the base soil. For soils with Cu 3 and low hydraulic gradients under steady flow conditions, CFEM (2006) recommends a minimal opening size to allow fines passing O90 3-di5 of the base. 

Usually, a large pore volume and sufficient thickness of the geotextile filter allow for a sufficient number of three-dimensional flow paths through the impregnated fabric. In this sense, the following requirements should be met  

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Trommel inclination, which usually varies between 2 and 5 degrees, affects the residence time of the waste material in the drum, as well as the trommel throughput. Other factors that affect the throughput are trommel diameter and filhng factor. Trommel screen is a valuable item of many solid waste-processing plants, as it appears to be a clogging resistant screen. 

The relationship of O95 with djs is used because the clogging resistance criterion is generally smaller (for silt/clay size particles) than the O95 value for soil retention. 

Takemasa, K. Kakino, R. Fabrication of presensitized lithographic plates and clogging-resistant photocurable inks therefor. Jpn. Kokai Tokkyo Koho JP 2008075056, 2008 Chem. Abstr. 2008, 148, 390923. 

As a dynamic Alter, the ECP must have sufficient durability to survive installation and he selected to have compatible openings and permeability to ensure clogging resistance. 

Doloma-based refractories have been applied to the continuous caster to prevent alumina clogging when casting aluminum killed steel grades. Tundish nozzles based on doloma have been used at BOF shops that cast a variety of aluminum killed steel grades. It was found that the sulfur content of the steel was critical with maintaining the clogging resistance of the doloma nozzles. 

Compared with traditional plate-and-frame exchangers, this design relies on a more loosely corrugated chevron pattern, which provides exceptional resistance to clogging. The plates are designed with few, if any, contact points between adjacent plates to trap fibers or solids. Some styles of this exchanger use wide-gap plates on the process side and conventional chevron patterns on the coolant... 

Nonwoven filter media are mostly used for filter medium filtration with pore clogging. Because of the relatively low cost of this medium, it is often replaced after pore clogging. In some cases, nonwoven media are used for cake filtration. In this case, cake removal is so difficult that it must be removed altogether from the filter medium. Nonwoven filter media can be prepared so that pore sizes decrease in the direction from the surface of the filter media contacting suspension to the surface contacting the supporting device. This decreases the hydraulic resistance of... 

Care must be taken with both sintered glass and porous base crucibles to avoid attempting the filtration of materials that may clog the filter plate. A new crucible should be washed with concentrated hydrochloric acid and then with distilled water. The crucibles are chemically inert and are resistant to all solutions which do not attack silica they are attacked by hydrofluoric acid, fluorides, and strongly alkaline solutions. 

Compact, ready-prepared calomel electrodes are available commercially and find wide application especially in conjunction with pH meters and ion-selective meters. A typical electrode is shown in Fig. 15.1(h). With time, the porous contact disc at the base of the electrode may become clogged, thus giving rise to a very high resistance. In some forms of the electrode the sintered disc may be removed and a new porous plate inserted, and in some modern electrodes an ion exchange membrane is incorporated in the lower part of the electrode which prevents any migration of mercury(I) ions to the sintered disc and thus... 

The most common technical problem is clogging of wells. Clogging is defined as an increased flow resistance for water to enter the well (or be disposed... 

The figure illustration shows occurrence of clogging by plotting data from an observation well (OW) and compare that to the production well (PW). In this case the production well shows a decreased specific capacity while the observation well shows a steady level versus time. The only explanation is then that the resistance for water to enter the production well is increasing. The increased resistance will lower the drawdown inside the well, while the groundwater table outside the well is kept constant. This will increase the hydraulic gradient (the driving force) between the well and the aquifer and hence maintain a constant flow rate. 

The new regulations also require that LCRSs be chemically resistant to waste and leachate, have sufficient strength and thickness to meet design criteria, and be able to function without clogging. 

In the second type of filtration, depth or deep-bed filtration, the particles penetrate into the pores of the filter medium, where impacts between the particles and the surface of the medium are largely responsible for their removal and retention. This configuration is commonly used for the removal of fine particles from very dilute suspensions, where the recovery of the particles is not of primary importance. Typical examples here include air and water filtration. The filter bed gradually becomes clogged with particles, and its resistance to flow eventually reaches an unacceptably high level. For continued operation, it is therefore necessary to remove the accumulated solids, and it is important that this can be readily achieved. For this reason, the filter commonly consists of a bed of particulate solids, such as sand, which can be cleaned by back-flushing, often accompanied by... 

System s polymer film properties and free oscillation as a fluidized array resists biofouling and iron clogging... 

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