Chevron Collectors

Weir redistributors These are identical to notched-trough distributors. Because weir redistributors cannot collect liquid from the upper section, a liquid collector such as a chimney tray or chevron collector (Chap. 4) or a collecting support plate (e.g., the upper plate in Fig. 3.8c) is usually required above the redistributor. 

Chimney trays (Fig. 4.10a, 6) are used for withdrawing intermediate liquid streams from the column in a packed tower, they are also used as liquid collectors or vapor distributors. Alternative devices used for liquid withdrawal are downcomer trapouts in tray columns, chevron collectors, and some redistributors in packed columns. Compared to these alternative devices, chimney trays have the following advantages ... 

Chevron collectors are used in packed columns as liquid collectors for partial drawoff or for feeding to a redistributor which is not selfcollecting (e.g., a notched-trough redistributor). They are sometimes also used as total drawoffs, but are less suitable than chimney trays for this purpose. The chevron collector (Fig. 4.13) consists of evenly spaced chevron blades several inches high. Liquid collects at the bottom of the blades and runs into a draw pan. From there it can be taken out or fed to a redistributor. 

Figure 4.13 Chevron collector. (G. K. Chen, excerpted by special permission from Chemical Engineering, March 5, 1980, copyright by Mdlraw-Hill, Inc., New York, NY 10020.)...

The chevron collector features a high open area for vapor flow, and is therefore a low-pressure-drop device. Pressure drop is usually less than 0.1 in of water (74). This type of collector is most suitable for vacuum applications. This collector also acts as a vapor distributor accordingly, the distance required between the top of this collector and the support plate above is less than 12 in (74). The short vertical distance requirement of this device compared to the chimney tray often makes it less expensive than the chimney tray. 

Primary steam separators These devices are located horizontally, immediately above the top drum waterline and use baffles or chevrons and dry pipe collectors, or cyclone or centrifugal action to radically change the steam flow, resulting in the heavier water and contaminants separating out from the steam. 

Two channelplates in a Chevron mounting can be used as a position-sensitive detector (see Fig. 4.18) provided the collector anode is able to preserve the position information which then has to be transferred to suitable electronics. Position-sensitive detectors are used in electron spectrometry mainly for four different applications ... 

Liquid collectors are installed when liquid must be collected for redistribution or drawoff (e.g., for external cooling). The common device used is a chimney tray, which is similar to an orifice redistributor, but without perforations. Another common device is the Chevron-type collector, which is a series of Chevron blades, with liquid being collected at the bottom of the blades. 

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