Slotted trays

Minor beam -- - support clamp Peripheral ring clamps (Note Slotted tray is frictionally held to promote breathing) Subsupport tray ring (used with angle ring)... 

One-Step Cameras and Processors. The eadiest one-step cameras used roU film and completed processing inside a dark chamber within the camera (9). The first instant color film, Polacolor, was provided in roU film format to fit these cameras. Flat-pack film cameras (Fig. 2), introduced in 1963, permitted the film to be drawn between processing rollers and out of the camera before processing was completed (10). Film holders for instant 10 X 13 cm (4x5 in.) film packets contain retractable rollers that permit the film to be loaded without mpturing the pod (11). For 20 x 25 cm (8 x 10 in.) films, the processing rollers are part of a tabletop processor. The exposed film, contained in a protective black envelope, and a positive sheet with pod attached are inserted into separate slots of a tray that leads into the processor. The film passes through the rollers into a covered compartment within which processing is completed. 

Fig. 11. Two-truck tray dryer. A, air inlet duct B, air-exhaust duct with damper C, axial flow fan D, fan motor, 2—15 kW E, air heaters F, air-distribution plenum G, distribution slots and H, wheeled tmcks and trays. The arrows iadicate air and vapor flow pattern.

HETP for a 2-in. slotted metal ring in a condensate stabilizer is about 36 in. This is slightly more than a typical tray design, which would require 34 in. (1.4 trays X 24-in. tray spacing) for one theoretical plate or stage. 

Vapor rises up through risers or up-takes into bubble cap, out through slots as bubbles into surrounding liquid on tray. Bubbling action effects contact. Liquid flows over caps, outlet weir and downcomer to tray below. Figures 8-63-67, 79, and 81. 

Figure 8-71B. Nutter LVG long, SVG short, and MVG tray slots. MVG tray slots are always placed in a triangular pattern. Used by permission, Nutter Engineering, Harsco Corp.

The height of an inlet weir, if used, should be 1 to l)f in. above the top of the slots of the bubble caps when installed on the tray. 

If inlet weirs are used they should have at least two slots %-in. by 1-in. flush with the tray floor to aid in flushing out any trapped sediment or other material. There should also be weep or drain holes below the downcomer to drain the weir seal area. The size should be set by the type of service, but a minimum of M-in. is recommended. 

The adjustable weir feature of many tray designs allows a standard tray to be utilized in different services by readjusting the weir height as needed. The fixed portion of the weir should never be lower than the top of the slots of the bubble caps. Depending upon service, the adjustable weir... 

A bubble tray blows when the vapor rate is extremely high, regardless of the liquid rate, causing large vapor streams or continuous bubbles to be blown through the liquid. The efficiency and contact is low and entrainment is usually high. Here also low slot seals contribute to the sensitivity of the tray to such action. 

A bubble tray cones when the liquid seal over the slot is low and the vapor rate is so high as to force the liquid completely away from the cap, thus bypassing the liquid entirely. Obviously, efficiency is unsatisfactory. The dynamic slot seals recommended in Table 8-18 normally will prevent such action. 

This is normally taken as the wet bubble cap pressure drop plus the mean dynamic slot seal in inches of clear or unaerated liquid on the tray. 

V = total vapor flow through tray, ft /sec Nc = number of caps per tray Ns = number of slots per cap Ws = width of slot (rectangular), in. 

The correcdon feictor, is obtained from Figure 8-115. Figure 8-115 applies to cap slots 1 in. through 2 in, and if slots are smaller (around A in.) the factor increases about 25% average (10-50%). The relation applies only to the pressure drop attributable to the conditions of liquid on the tray up to the top of the slots. 

The actual operating or dynamic slot seal is more indicative of conditions pertaining to the tray in operation and is [5] ... 

Tower shells may be ferrous, non-ferrous, stainless alloys or clad (such as monel-clad-steel). The trays are usually light gage metal consistent with the corrosion and erosion problems of the system. The velocity action of vapors flowing through holes and slots accentuates the erosion-corrosion problems, and often a carbon steel tower will use... 

Pressure drop through dry slots, in. liquid Static liquid seal on sieve tray, in. liquid Static slot seal, in. 

Total number of actual trays in tower Number of caps per tray Number of slots per bubble cap Valve density, number of valves per ft or Number of valve units on a valve tray Depth of notches in weir, in or Exponent defined by Equations 8-288 and 327 Dry tray pressure drop for 50% cut baffles, in. liquid per baffle or... 

V-GRID tray Tapered slot M Mod Med Med Med Fixed open, high... 

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