Prospectus

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DST-6 System Limit on Trays Expected Benefit toMembers: With the rise in popularity of high-capacity trays, the system limit is often approached. The tray designer needs additional information on this limit and factors that affect it on trays. Present Situation and Proposed Research: FRI only has a handful of data on system limit in trays with downcomers. Recent changes to FRI’s system limit correlation produced prediction differences as high as 30-50% for sieve trays. The current tiny system limit data bank provides an insufficient basis to confirm or deny even such large differences in prediction. There is an absence of data showing how system limit on downcomer trays is affected by liquid rate, hole diameter, and horizontal blowing such as that experienced on several high-capacity trays. There is a debate going on whether the system limit is a function of the superficial or free area in a tray with downcomers - a very large difference! Again, the existing data bank is too tiny to provide an answer. Simulator work is proposed using air-Isopar™ at several tray spacings starting at 36 inches, increasing the tray spacing until capacity no longer increases. Tests are proposed with sieve trays of different hole sizes, hole areas, downcomer top areas, one valve tray, and one proprietary tray (already tested by FRI) with horizontal vapor flow. Proposed Internals and Test System: Traditional Research Idea

Estimated Unit Time: Four operating weeks for each tray, total eight weeks. Estimated Additional Costs (Beyond Unit Time): Simulator work will likely be contracted out ($50,000).

Two tray designs will subsequently be developed and tested at 36 or 48-inch tray spacing in the high-pressure column with systems over the entire pressure range.

Background and Discussion: The proposed program will give insight into the nature of system limit on downcomer trays and into the factors that affect the limit. It will give engineers an idea as to when increasing tray spacing can be used for tower debottlenecking. It will also provide an answer on when a high capacity tray can provide capacities that exceed the system limits in conventional trays. It may also point out regions where use of some high capacity trays may be of limited benefit.

PROSPECTUS

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