Plate areas

The following areas terms are used in the plate design procedure  

An = net area available for vapour-liquid disengagement, normally equal to Ac — Ad, for a single pass plate, 

Afl = active, or bubbling, area, equal to Ac — 2Ad for single-pass plates, 

Ah = hole area, the total area of all the active holes, 

The flooding condition fixes the upper limit of vapour velocity. A high vapour velocity is needed for high plate efficiencies, and the velocity will normally be between 70 to 

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As of 1990, plastics are plated in fewer than 50 U.S. plants. The aimual electroless chemical costs range from 7—10 million for POP, and 5—7 million for REl shielding. Individual plants process from 4.6 x 10 to >1.3 x 10 /yr of plastic surface area. Automotive items make up over 50% of the market on a plated area basis the remainder is hardware, plumbing, electronics shielding, and decorative items. 

Ratio of slot (bubble cap), perforation (sieve), or full valve opening (valve plate) area A/, to active area A is 0.1 or greater. Otherwise the value of U j obtained from Fig. 14-25 should be corrected ... 

The fraction of plate area occupied by disengaging and distributing zones ranges from 5 to 20 percent of the cross section. For most sieve-plate designs, these zones are eliminated completely. 

The area that is theoretically available for separation is equal to the sum of the projected areas or all channels on the horizontal plane. Figure 18-88 shows the horizontally projected area A, of a single channel in a clarifier of unit width. If X is the uniform distance between plates (measured perpendicularly to the plate surface), the clarifier will contain sin Ci/X channels per unit length and an effective collection area per unit clarifier length of A, sin O/X, where Ot is the angle of inclination of the plates to the horizontal. It follows that the total horizontally projected plate area per unit volume of sludge in the clarifier Aj is... 

Erom C-1.1 the equation for capacitance of a parallel plate capacitor (plate area A, separation d) s ... 

S" = clear height above foam or froth (equals tray spacing minus foam height above tray floor), ft p = viscosity of liquid, centipoise a = surface tension of liquid, dynes/cm We = entrainment (based on assumed allowance) lbs liquid/ (ft free plate area) (hr) hf = height of top of foam above tray floor, in. 

Note All holes < 4-in. dia and about 10% of tray active hole area referred to plate area between weirs. 

From Figure 8-144 or by calculation determine the plate area required for the holes on the pitch selected. Several selections may be tried to be used with the tray layout. These should be checked to agree with the assumed per cent hole area of Step 3. 

Use Figure 8-144 to aid in the determination. If more plate area is required than is available, back-calculate the necessary maximum hole velocity. Check if this is reasonable (say not over twice the minimum). If so, the diameter is still acceptable or change the hole spacing to allow more or fewer holes to be placed in the given diameter of the tower. Use limiting values previously given on hole spacing. 

Plates are available with effective heat transfer area from 0.03 to 3.5 m and up to 700 can be contained within the frame of the largest plate-type heat exchanger, providing over 2400 m of surface area. Flow ports and associated pipework are sized in proportion to the plate area and control the maximum liquid throughput. 

Taking area 1 as that of the plate, area 2 as the underside of the hemisphere, area 3 as an imaginary cylindrical surface linking the plate and the underside of the dome which represents the black surroundings and area 4 as an imaginary disc sealing the hemisphere and parallel to the plate, then, from equation 9.134, the net radiation to the surface of the plate 1 is given by ... 

In the periphery at the mammalian neuromuscular junction each muscle fibre is generally influenced by only one nerve terminal and the one NT acts on one type of receptor localised to a specific (end-plate) area of the muscle. The system is fitted for the induction of the rapid short postsynaptie event of skeletal muscle fibre contraction and while the study of this synapse has been of immense value in elucidating some basic concepts of neurochemical transmission it would be unwise to use it as a universal template of synaptic transmission since it is atypical in many respects. 

The corrugations on the plates will increase the projected plate area, and reduce the effective gap between the plates. For rough sizing, where the actual plate design is not known, this increase can be neglected. The channel width equals the plate pitch minus the plate thickness. 

Select an effective plate area of 0.75 m2, effective length 1.5 m and width 0.5 m these are typical plate dimensions. The actual plate size will be larger to accommodate the gasket area and ports. 

Equation 9.61 is only approximate at best. For distillation trays with long flow paths across the active plate area, Equation 9.61 tends to underestimate the overall efficiency. 

A coal combustion pilot plant is used to obtain efficiency data on the collection of particulate matter by an electrostatics precipitator (ESP). The ESP performance is varied by changing the surface area of the collecting plates. Figure E2.2 shows the data collected to estimate the coefficients in a model to represent efficiency 17 as a function of the specific collection area A, measured as plate area/volumetric flow rate. 

Cp = cost per square foot of plate area, /ft2 A = column cross-sectional area, ft2 N = number of plates A min = minimum number of plates Cs = cost of shell, /ft3 H = distance between plates, ft Cf = cost of feed pump, ... 

Baffle-tube support plate area, in thermal design, 13 258 Bafilomycin A, 2 817 Bag and drum filling, industrial hygiene and, 14 209 Bagasse, 23 444, 447 burning, 23 449-450 uses for, 23 483 Bag cleaning... 

Substituting equations 3.26 and 3.27 into equation 3.29 results in an expression for the mass production rate per unit plate area, thus... 

Figure 3.10 Production rate of frozen peas per unit plate area as a function of bed height and bed length. From Vazquez and Calvelo (1983b), by permission of the Institute of Food Technologists, USA.

Figure 20.1 illustrates a third method of measuring the mercury level. The mercury in the dilatometer stem constitutes one plate of a capacitor and a metal sheath coaxially surrounding the dilatometer serves as the second plate. The capacitance changes with the mercury level due to the variation of the effective plate area. 

A voltage of 10 V is applied across a parallel-plate capacitor with a plate separation of 2 X 10 m and plate area of 6.45 x 10 m, both in vacnnm and then with a dielectric material placed between the plates. The polarization, P, dne to the presence of the dielectric material is 2.22 x 10 C/m. ... 

Contact plate areas vary from 24 to 30 cm. When swabbing is used in sampling, the area covered should be greater than or equal to 24 cm but no larger than 30 cm. ... 

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