Chemical Engineering September 2021 - 32

In comparison to the author's
2010 work, the new minimum stability
factor can now have values
less than the 0.6 fixed value (as
given in 2010) when column operating
pressures are high. However,
when operating pressures are low,
stability factor values will more than
likely need to be higher than the
original 0.6 value.
Alternative equation
An alternative equation based on
surface tension for the minimum
stability factor can be used, as
expressed in Equation (9)
in the
CIC-10307 halfp page ad.qxd 3/25/07 6:19 PM Page 1
box. The parity plot for this equation,
Figure 12, is really no different
than the parity plot for Equation (8).
Therefore, for those people who
think that the controlling physical
property to best represent the
pressure effect is surface tension,
then Equation (9), shown in
the Stability Factor Expressions
box, is a satisfactory alternative. ■
Edited by Mary Page Bailey
Acknowledgement
The author would like to acknowledge
the help he received years ago from
Zane King of Sulzer. As an intern, he
was able to take the public domain
data from FRI and plot it into a usable
and visual form for the author so that
(after he retired from Sulzer) his work
was made so much easier. Also, the
author would like to acknowledge FRI
for 70 years of industrial distillation
data. FRI is a not-for-profit worldwide
consortium of approximately 85 companies
involved with distillation design
ranging from equipment manufacturers
to engineering companies to operating
companies. FRI offers important
deliverables to the distillation industry,
including: industrial-scale column operating
data; design and rating correlations
for both packings and trays;
and design practices handbooks.
References
1. Summers, D. R., Spiegel, L., and Kolesnikov, E., Tray Stability at
Low Vapor Load, Conference Proceedings of Distillation and
Absorption 2010, p. 611, Eindhoven, The Netherlands, September
12-15, 2010.
2. FRI Sieve Tray Database - Public Domain files, Oklahoma State
University Special Collections and University Archives.
3. Summers, D. R., Dry Tray Pressure Drop of Sieve Trays, Chem.
Eng., June 2009, pp 36¬39.
4. Summers, D. R., Cai, T. J. Dry Tray Pressure Drop of Sieve Trays
Revisited, Chem. Eng., August 2017, pp 38-41.
5. C. J. Colwell, Clear Liquid Height and Froth Density on Sieve
Trays, Ind. Eng. Process Design and Development, Vol. 20, pp
298-307, April 1981.
6. Summers, D. R., Bubble-Cap Tray Vapor Turndown, Chem. Eng.,
February 2018, pp 38-41.
Author
Dan Summers was (until 2021)
the Tray Technology manager for
Sulzer Chemtech. After graduating
from SUNY at Buffalo in 1977,
he started his career with Union
Carbide's Separations Design
group in West Virginia. He has
also worked for Union Carbide
Linde Division (now Linde plc),
UOP, Stone & Webster (now Technip
Energies), and Nutter Engineering. His entire career
has been focused exclusively on distillation. He is the
author of over 70 papers on distillation and is a listed
inventor on three U.S. patents. At present, Summers is
a consultant for FRI's Design Practices Committee, and
served as the chair of that committee for 12 years. He
is also a director and the awards co-chair of AIChE's
Separations Division. He is a registered professional
engineer in both New York and Oklahoma, and is a Fellow
of AIChE. He is also a recipient of the Gerhold
Award for outstanding work in the Application of Chemical
Separations Technology.
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