Chemical Engineering October 2015 - 75

tunity for any debris or water collection
at the low point (Figure 7).
Another way to reduce the piping
stress is to consider the use of a
spring hanger (which helps to reduce
or eliminate the external force from
the piping) near the drain nozzle. The
straight drain line is resisted by the
spring hanger at the top of the drain
nozzle of the molecular seal drum,
and the drain line at the bottom is
connected with flexible hose, which
can absorb some thermal expansion
and also can make it easier to carry
out steam blowing or cleaning.
Molecular seal drums are commonly
made of low-carbon steel,
therefore, the bottom and wall are
subjected to corrosion due to the
formation of condensate with corrosion
particles from the off-gas. In
this regard, the molecular seal drum
often requires preventive repairs,
as well as periodic checks of wall
thickness, and removal of condensate
and refractory debris from
the bottom.
In order to improve the strength
of the molecular seal drum, an ellipsoidal-type
bottom head can be
considered instead of the conventional
flat-plate type. This design
provides improved strength of the
weld joint, as well as less plugging
due to the configuration of the ellipsoidal
head.
Although most flares (Figure 8) actually
operate at a pressure less than
15 psig, it is not usually necessary to
consider the molecular seal drum as
a pressure vessel. Typically for this
design, the rules of the ASME Boiler
and Pressure Vessel code [5] can be
applied, and can be used as means
to ensure fabrication quality.
In order to improve operating
safety, protect personnel and the
environment, and avoid costly shutdowns,
it is critical to design, operate
and maintain molecular seal systems
properly. The failure cases discussed
here provide useful insight for improving
the design in order to reduce
losses and prevent shutdowns and
flare outages.
n
Edited by Suzanne Shelley
References
1. American Petroleum Institute, Guide for Pressure-relieving
and Depressing Systems, API Recommended Practice
521, 6th Ed., January 2014.
2. American Petroleum Institute, API Standard 537, Flare
Details for General Refinery and Petrochemical Service,
API Standard 537, Draft 3rd Ed., Sept. 2001.
3. John Zink Co., " The John Zink Hamworthy Combustion
Handbook, " Vol.3, Applications, Chapter 11: Flares, CRC
Press LLC, 2001.
4. Shore, David, Making the flare safe, J. Loss. Prev.Process
Ind., Vol. 9, No. 6, pp. 363-381, 1996.
5. ASME, ASME International Boiler and Pressure Vessel
Code, Sec. VIII, Div. 1, Pressure Vessels, 2015 Ed.
Author
Hyunjin Yoon is a master engineer
of fired equipment at SK Energy
(2, Sinyeocheon-ro, Nam-gu,
Ulsan 680-130, South Korea;
Email: hj.yoon@sk.com; Phone:
+82-10-3570-0106). He received
an M.S. degree in material science
and engineering from Stanford
University (Palo Alto, Calif.),
and a B.S. in mechanical engineering
from Hanyang University in South Korea. Yoon
has more than 27 years of petrochemical industry experience.
He has broad experience in fired-equipment
design, troubleshooting and maintenance. He is credited
with major roles and involvement in the development
of specifications and various maintenance procedures
for stationary equipment.
When it comes to harsh
operating environments...
Content Licensing for
Every Marketing Strategy
Marketing solutions fit for:
* Outdoor
* Direct Mail
* Print Advertising
* Tradeshow/POP Displays
* Social Media
* Radio & Television
Logo Licensing |
Reprints
Eprints | Plaques
Leverage branded content from Chemical Engineering
to create a more powerful and sophisticated statement
about your product, service, or company in your
next marketing campaign. Contact Wright's Media
to find out more about how we can customize your
acknowledgements and recognitions to enhance your
marketing strategies.
For more information, call Wright's Media at 877.652.5295
or visit our website at www.wrightsmedia.com
The NEW Chucket,
Chain Storage Bucket
We've got
you covered.
Roto Hammer is pleased to
offer another NEW product -
Stainless Steel Chain Wheels for:
* Harsh operating environments
* High moisture environments
We also offer galvanized chain wheels to
extend the life of the product in corrosive
environments.
Our entire CL Series line of chain wheels is
available in stainless steel. All components
of the chain wheel are constructed of 316
stainless steel.
Call us today toll free:
1-800-477-7686
918-446-3500 * rotohammer.com
®
Also available:
The NEW Chuckout
with Lockout/Tagout
feature - patent pending
INDUSTRIES
Since 1959
Circle 26 on p. 102 or go to adlinks.chemengonline.com/56202-26
ChemiCal engineering www.Chemengonline.Com oCtober 2015
75
NEW
NEW
http://www.rotohammer.com http://www.wrightsmedia.com http://adlinks.chemengonline.com/56202-26 http://www.Chemengonline.Com
Chemical Engineering October 2015

Table of Contents for the Digital Edition of Chemical Engineering October 2015
