Prospectus

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DST-4 3-Pass Trays

Traditional Research Idea

Expected Benefit to Members: Improved design correlations would permit more accurate predictions of column capacity and efficiency. Multi-pass trays could be specified in lieu of two-pass trays to reduce column diameter or tray spacing for a given jet-flood and downcomer backup limit. Present Situation and Proposed Research: Multi-pass trays are typically specified for high liquid rate applications to reduce weir loadings and to mitigate the negative associated effects such as jet flooding, pressure drop, and downcomer backup. Design methods may be found in the open literature and in suppliers' know-how, but approaches are inconsistent. It is proposed that three-pass trays be tested in the 8-foot section of the low-pressure column. Tests would be performed using the iC4/nC4 system at 165 psia (the limit for the low-pressure column) as an example of a high liquid rate system where multi-pass trays would be considered. Data taken would include capacity and efficiency for the overall tray as well as for each panel to attempt to quantify the effects of varying L/V ratios. Prior to entering into the hardware design, a literature search will be conducted to assimilate the available philosophies and correlations dealing with the design of multi-pass trays. The literature search will also identify gaps in design approaches. Member companies will be surveyed to assess experiences (positive and negative) with multi-pass trays and to invite them to forward Trays would be commercially fabricated, 1/2-inch hole diameter 11% sieve trays with 2-inch weir height. Two different three-pass tray designs would be tested - 1) a design based on equal flow path length; and 2) a design based on equal bubbling area. All other parameters (weir height, hole size, fraction hole area, downcomer clearance, etc.) would remain the same for both designs. Estimated Unit Time: Three weeks per tray design, six weeks’ total. Estimated Additional Costs (Beyond Unit Time): To achieve high loadings in the 8-foot section, it is necessary to complete portions of the current capital upgrade program. any design methods they feel appropriate. Proposed Internals and Test System:

PROSPECTUS

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