Adjustable weir

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... 

Adjustable weir plate with slotted bolt holes Use 3-3/s 0 bolts See Detail B ... 

Adjustable weir plate w/slotted bolt holes... 

Adjustable weirs (Fig. 14-22 ) are used to provide additional flexibility. They are uncommon with conventional trays, but are used with some proprietary trays. Swept-back weirs (Fig. 14-22b) are used to extend the effective length of side weirs, either to help balance liquid flows to nonsymmetric tray passes or/and to reduce the tray liquid loads. Picket fence weirs (Fig. 14-22c) are used to shorten the effective length of a weir, either to help balance multipass trays liquid flows (they are used in center and off-center weirs) or to raise tray liquid load and prevent drying in low-liquid-load services. To be effective, the pickets need to be tall, typically around 300 to 400 mm (12 to 16 in) above the top of the weir. An excellent discussion of weir picketing practices was provided by Summers and Sloley (Hydroc. Proc., p. 67, January 2007). 

A flowing film was established by means of a plate of 400 mm length and 70 mm breadth which was installed inside of a revolving autoclave. The film thickness at liquid inlet could be varied by means of an adjustable weir. Depending on the inclination angle a of the plate the mean film thickness 8 yields... 

Adjustable weirs (Fig. 6.7a) were common in early designs. Their intent was to provide flexibility for interchanging capacity and efficiency, but their effectiveness was generally limited. This design is no longer recommended because experience has shown that maladjustments of the weirs outweigh the potential benefits (123, 211, 399). 

A4. Another type of weir not shown in Figure 10-6 is the adjustable weir. In an adjustable weir the height can be changed by loosening bolts, moving the weir, and retightening the bolts. List as many reasons as you can think of why this type of weir is generally not recommended. 

For transport around a process plant, gravity flow, rather than pumping of fluids, is an attractive option. There is no pump to fail. There are some very simple options for control, for example by regulated overflow over an adjustable weir - an attractive control option in the case of very abrasive slurries. 

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