How Trays Work Flooding

There are two types of tray decks perforated trays and bubble-cap trays. In this chapter, we describe only perforated trays, examples of which are 

Possibly 90 percent of the trays seen in the plant are of these types. Perforated tray decks all have one feature in common they depend on the flow of vapor through the tray deck perforations, to prevent liquid from leaking through the tray deck. As we will see later, if liquid bypasses the outlet weir, and leaks through the tray deck onto the tray below, tray separation efficiency will suffer. 

Distillation trays in a fractionator operate between 10 and 90 percent efficiency. It is the process person s job to make them operate as close to 90 percent efficiency as possible. Calculating tray efficiency is sometimes 

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How about the 10 trays shown in Fig. 3.4 Calculate their average efficiency (answer is 10 percent). As the vapor temperature rising from the top tray equals the liquid temperature draining from the bottom tray, the 10 trays are behaving as a single perfect tray with 100 percent efficiency. But as there are 10 trays, each tray, on average, acts like one-tenth of a perfect tray. 

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