Scouring action

Scheuer-pulver, n. scouring powder, -trommel, /. scouring barrel, tumbling barrel, -wirkung, /. scouring action or effect. 

Steele, A., Scouring Action in Piping, Heating/Piping/Air Conditioning, May 1981, p. 89. 

The second approach assigns thermal resistance to a gaseous boundary layer at the heat transfer surface. The enhancement of heat transfer found in fluidized beds is then attributed to the scouring action of solid particles on the gas film, decreasing the effective film thickness. The early works of Leva et al. (1949), Dow and Jacob (1951), and Levenspiel and Walton (1954) utilized this approach. Models following this approach generally attempt to correlate a heat transfer Nusselt number in terms of the fluid Prandtl number and a modified Reynolds number with either the particle diameter or the tube diameter as the characteristic length scale. Examples are ... 

These are fine dental preparations used to help the scouring action to toothbrush mechanically. And, abrasion is defined as the wearing away of a substance or structure through a mechanical process, such as grinding, rubbing or scrapping. The abrasives is made into a paste and supplied in a tube. 

Abrasive cleaners arc used lo remove soils and stains from hard surfaces that are durable lo the scouring action. Such surfaces include stainless steel and porcelain plumbing fixtures, metal and ceramic cooking utensils, and various stone, metal, and ceramic building surfaces. Typically, these products consist of a very high level of abrasive (commonly silica flour) with moderate to low levels of a dry chlorine bleach (KDCC or chlorinaled trisodium phosphate) and low levels of surfactant (LAS) and builder (STP) for wetting action and improved stain removal... 

In theory, cross-flow is a continuous operation, as the scouring process keeps the membrane surface free of foulants. In practice, however, the scouring action of cross flow is not always enough to prevent all fouling and scaling. Periodically, the membranes will need to be taken off line and cleaned free of material that has accumulated at the surface. 

Another technique developed to minimize losses of compound on container surfaces is described by Chen and Dority ( ) and by de Klein (29), in which the sample is deposited in a capillary tube. The powdered potassium bromide can be added to the capillary tube either prior to the addition of the sample or afterwards mixing is accomplished in the latter case by shaking and letting the scouring action of the potassium bromide reduce residual tubing surface losses. 

A simple equation for ascertaining the relative cost of common sizes of screw conveyors is given as Formula 17, but the one for calculating the relative depreciation per year is complicated by the introduction of the depreciation factor necessarily entailed when the moving parts of the conveyor are in direct contact with the load in a manner which produces a destructive abrasive, or scouring, action. 

Granular activated carbon is mixed in with the CST feed, except when carbon from the HVAC system is being treated, to maintain scouring action in the CST and minimize charring during processing runs for DPE suit material. The CST discharge is screened to separate activated carbon from the ash, and the reusable carbon is recycled to the feed end. 

Nonetheless, the construction of a dam across a river can lead to other problems. It decreases the peak discharge and reduces the quantity of bedload through the river channel. The width of a river may be reduced downstream of a dam as a response to the decrease in flood peaks. Moreover, scour normally occurs immediately downstream of a dam. Removal of the finer fractions of the bed material by scouring action may cause... 

Abrasion/Erosion Wearing avray of the surface by the scouring action of the process environment... 

Bacterial polysaccharides have other roles in the natural environment that depend less on their antigenic specificity. Polysaccharide slime secreted by bacteria can serve as an adhesive, allowing microbial exo-systerns to resist the scouring action of water flow. The maintenance of good crumb structure in soils depends upon the exopolysaccharides of bacterial origin. 

Oil-based compounds with abrasives (such as sand) to achieve a dry scouring action where much soil or dirt is present. 

Several catalyst systems have recently been developed that re.sist poisoning by chlorine. An example is the ARI International Econ-Abator system, which uses chromia-alumina catalyst granules in a shallow fluidized or moving bed (ARI International, 1992). The catalyst is formulated by impregnating chromia throughout a porous gamma alumina substrate. The catalyst particles are kept clean by the scouring action of the fluidized bed, which continuously exposes fresh active catalyst to the gas stream (Parkinson, 1991). 

A major development in filtration, which came with the first, reverse osmosis membrane process, was the fact that the flow of the fluid at the membrane snrface is tangential to it, rather than perpendicular to that surface. This has become known as cross-flow filtration (see Figure 2.21), and almost all membrane processes now operate in crossflow rather than through flow mode. Further scouring action is achieved by having the membrane medium move relative to the hquid flow, either rotating close to a stator, or vibrating. 

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