Dimpling

An obvious method of increasing the filtration area in the vessel is to stack several plates on top of each other the plates are operated in parallel. One design, known as the plate filter, uses circular plates and a stack that can be removed as one assembly. This allows the stack to be replaced after the filtration period with a clean stack, and the filter can be put back into operation quickly. The filter consists of dimpled plates supporting perforated plates on which filter cloth or paper is placed. The space between the dimpled plates and the cloth is coimected to the filtrate outlet, which is either into the hoUow shaft or into the vessel, the other being used for the feed. When the feed is into the vessel, a scavenger plate may have to be fitted because the vessel will be full of unfiltered slurry at the end of the filtration period. This type of filter is available with filtration areas up to 25 m and cakes up to 50 mm thick. 

P). Otherwise the baffles should be located iaside the cod helix. A conventional jacket consists of a vessel outside the main vessel with a gap for the flow of heat-transfer fluid. Half-pipe jackets are usefld for high pressures up to 4 MPa (600 psi). They are better for Hquid than for vapor service fluids and can be easdy 2oned. Dimple jackets are suitable for larger vessels and process conditions up to 2 MPa (300 psi) and 370°C. Internal cods can be either hehcal or baffle cods (Fig. 34). 

Enamel Defects. Characterization of defects in porcelain enamel surfaces frequently requites detailed examination via microscopy to determine the sources of the defects. Defects ate divided into processing and material defects. The greatest number of defects result from processing bhsters, pinholes, black specks, dimples, tool marks, and chipping. Defects often occur from unobserved sources at almost every stage of the enameling process, but they ate not recognizable until the ware is fired. Conscientious process control helps to minimize the incidents of unacceptable finishes. 

The half-pipe jacket is used when high jacket pressures are required. The flow pattern of a liquid heat-transfer fluid can be controlled and designed for effective heat transfer. The dimple jacket offers structural advantages and is the most economical for high jacket pressures. The low volumetric capacity produces a fast response to temperature changes. 

Pit interiors are characteristically smooth and distinctly hemispherical, but become rougher on less-noble alloys. Pits tend to cluster together, overlapping to form irregularly dimpled surfaces. Frequently, a lightly etched aureole surrounds the pit clusters. These etched areas are often produced by shallow corrosion beneath deposit and slime masses that covered the sulfate reducers in service (Figs. 6.3 and 6.4A and B). 

The equivalent diameter D,. in a dimpled jacket equals 0.66 m. the cross-sectional flow area equals 1.98 m." per foot of vessel circumference. 

The coefficients are not very accurate due to turbulence created by the dimples m the flow steam. 

The A, Aq, T and Tq valves can be supplied either with a flat periphery for tightest shutoff against liquid weepage at turndown rates or with a three-dimpled periphery to minimize contact with the tray deck for fouling or corrosive conditions. 

Figure 10-158A. Styles of Mueller Temp-Plate heat transfer plates. (1) Double-embossed surface, inflated both sides. Used in immersion applications, using both sides of the heat transfer plate. (2) Single-embossed surface, inflated one side, used for interior tank walls, conveyor beds. (3) Dimpled surface (one side), available MIG plugwelded or resistance spot welded. Used for interior tank walls, conveyor belts. (Used by permission Bui. TP-108-9, 1994. Paul Mueller Company.)...

The desire for cost savings starts with utilization of material. Is the continuous vertical rib necessary Interrupted rib versions [56] or so-called dimples [47] have been proposed repeatedly, but they have not succeeded because production or proc-... 

There are different techniques that have been used for over a century to increase the modulus of elasticity of plastics. Orientation or the use of fillers and/or reinforcements such as RPs can modify the plastic. There is also the popular and extensively used approach of using geometrical design shapes that makes the best use of materials to improve stiffness even though it has a low modulus. Structural shapes that are applicable to all materials include shells, sandwich structures, and folded plate structures (Fig. 3-8). These widely used shapes employed include other shapes such as dimple sheet surfaces. They improve the flexural stiffness in one or more directions. 

B. The direct identification of such microscopic fracture modes as transgranular cleavage, radial fracture, intergranular separation or ductile dimpled rupture, was shown to be considerably more dependable by SEM than by OM... 

Now consider adding a third layer of close-packed spheres. This new layer can be placed in two different ways because there are two sets of dimples in the second layer. Notice in Figure ll-29b that the view through one set of dimples reveals the maroon spheres of the first layer. If spheres in the third layer lie in these dimples, the third... 

In either of these close-packed structures, each sphere has 12 nearest neighbors 6 in the same plane, 3 in the dimples above, and 3 in the dimples below. The expanded views in Figure 11-30 show the different arrangements of the hexagonal and cubic close-packed crystalline types, hi the hexagonal close-packed structure, notice that the third layer lies directly above the first, the fourth above the second, and so on. The layers can be labeled ABAB. 

Breast Right Hard 2.4 x 3.0 cm mass in upper outer quadrant without associated erythema, dimpling, or skin changes, not fixed to skin, no ulceration. No palpable lymph nodes in axilla. Left Without masses or lymphadenopathy. 

Figure 12.72. Jacketed vessels, (a) Spirally baffled jacket (b) Dimple jacket (c) Half-pipe jacket (d) Agitation...

Dimpled jackets are similar to the conventional jackets but are constructed of thinner plates. The jacket is strengthened by a regular pattern of hemispherical dimples pressed into the plate and welded to the vessel wall, Figure 2.12b. 

In dimpled jackets a velocity of 0.6 m can be used to estimate the heat transfer coefficient. A method for calculating the heat transfer coefficient for dimpled jackets is given by Makovitz (1971). 

This equation gives the critical pressure required to cause general buckling local buckling can occur at a lower pressure. Karman and Tsien (1939) have shown that the pressure to cause a dimple to form is about one-quarter of that given by equation 13.59, and is given by ... 

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