No-mix and ideal separation cascades

Journal Article · Tue Nov 01 04:00:00 EST 1994 · Separation Science and Technology

DOI:https://doi.org/10.1080/01496399408003175· OSTI ID:35558

Herbst, R S ^[1]; McCandless, F P ^[2]

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1. Westinghouse Idaho Nuclear Co., Inc., Idaho Falls, ID (United States)
2. Montana State Univ., Bozeman, MT (United States)

Ideal countercurrent recycle cascades are characterized by two properties: (1) The compositions of heads and tails streams forming the feed stream to individual stages are the same, and (2) the heads separation factor for each stage is constant. When the two criteria are met, the heads and tails separation factors are constant and equal to the square root of the stage separation factor. The mixing of streams with different compositions within a separation cascade obviously constitutes an inefficiency since it is precisely the reverse of this process that is desired, hence Condition 1, which is often referred to as the no-mix criterion. Separation cascades for which both criteria are valid are termed ideal. However, the ramifications of Condition 2 are not obvious and it is possible to design no-mix cascades which do not meet the second condition. Mathematical relationships between ideal and no-mix separation cascades are derived to quantify these differences. It is shown that Condition 2 minimizes the total interstage flow required to make a given separation for any no-mix cascade design, i.e., it is an ideal cascade by definition. Finally, the required number of ideal stages necessary to perform specific separation with no-mix cascades are evaluated and compared to those of the ideal cascade.

• Sponsoring Organization: USDOE
• OSTI ID: 35558
• Journal Information: Separation Science and Technology, Journal Name: Separation Science and Technology Journal Issue: 17 Vol. 29; ISSN 0149-6395; ISSN SSTEDS
• Country of Publication: United States
• Language: English

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