Chemical Engineering May 2015 - 72

and (4) give 59,800 kJ/s or about 60
MW of power released by the flare.
This value drops to about 40 MW
with the introduction of a FGRU that
reduces the volume of gas flared by
about 40% (35.9 m.t./h).
For the same 40% reduction in
flare gas being flared, Equation (4)
shows a reduction in sound emissions
by about 6.8 dB.
Payback
Table 3 shows that the total investment
costs for the FGRU proposed
in Figure 5, which is capable of handling
a flare-gas stream of 90 m.t./h,
is about $30 million [13, 14].
Based on the installation of such a
FGRU after the cold flare drum, we
have calculated that 43.3 m.t./h of
ethylene and 10.8 m.t./h of fuel gas
can be recovered and returned to
the olefin plant. The value of the recovered
gases is roughly equivalent
to about $52,000/h.
According to monitoring studies,
this olefin plant has about 185 hours
of flaring per year during planned or
Table 3. invesTmenT cosTs for one
eThylene-planT fgrU
Cost
$16,900,000
$3,890,000
$997,000
$797,000
$5,980,000
$26,300
$29,800,000
Item
Equipment
Instrumentation
Piping
Electrical
Operation
Construction and installation
Total
unplanned shutdowns. This means
that about $9 million/yr of valuable
gases are returned to the plant and
the investment costs are recovered
after about three years of operation
of the FGRU. The environmental
benefits of reduced emissions of pollutants,
noise and thermal radiation
are an added bonus.
■
Edited by Gerald Ondrey
Acknowledgment
The authors would like to thank
Najem Beg and Sacha Sarshar from
Caltec Co., and Gholamreza Jokar
and Shapour Taghipour from Morvarid
Petrochemical Plant for their
support and guidance.
Refrences
1. Process Analytics in Ethylene Production Plants, Oil &
Gas Industry, 2007.
2. Ghadyanlou, F., " Flare Design, " 1st ed., Andishesara
Publishing Co., March, 2011.
3. Shahini, M., " Flare Gas Management, " Jahanno Publishing
Co., 2th Ed., March 2011.
4. Baukal, C.E. and Schwartz, R. E., " The John zink Combustion
Handbook, " 1st ed., CRC Press,March 27, 2001.
5. Falaqi, F. H., " The Miracle of Petrochemicals-Olefin Industry:
An In-Depth Look at Steam Crackers, " Universal
Publishers, Fla., 2009.
6. Liu, C., and Xu, Q., Emission Source Characterization
for Proactive Flare Minimization during Ethylene Plant
Start-ups, Ind. Eng. Chem. Res., 49, 2010, pp. 5,734-
5,741.
7. Yang, X, Xu, Q. and Li, K., Flare Minimization Strategy
for Ethylene Plants, Chem. Eng. Technology, 33, No. 7,
2010, pp. 1,059-1,065.
8. Page, J. E., " Reduction of Hydrocarbon Losses to Flare
Systems, " 1st Industry Technology Conference, Houston,
April 22-25,1979.
9. Zadakbar, O., Vatani, A. and Karimpour, K. Flare Gas Recovery
in Oil and Gas Refineries, Oil and Gas Science
and Technology, Rev. IFP, Vol. 63, No. 6, 2008, pp.
705-711.
10. Blanton, R. E., Environmentally and Economically Benefical
Flare Gas Recovery Projects in Petrochemical Facilities,
National Petroleum Refiner's Assn. Environmental Conference
West, San Antonio, Tex., September 2010.
11. AP-42, Compilation of Air Pollutant Emission Factors,
5th ed., U.S. Environmental Protection Agency, Washington,
D.C., www.epa.gov/ttnchie1/ap42.
12. VDI 3732 - Characteristic Noise Emissions Values of
Technical Sound Sources - Flares, VDI Guideline, Verein
Deutscher Ingenieure, Düsseldorf, Germany, 1990.
13. Trambouze, P., " Petroleum Refining - Material and
Equipment, " Vol. 4,Technip Editions, Paris, 1994.
14. M. Peters, M., Timmerhaos, K. and West, R. E., " Plant
Design and Economic for Chemical Engineers, " 5th ed.,
McGraw-Hill Co. New York, December 2002.
Authors
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70
Farhad Ghadyanlou is the
manager of the R&D Dept. of the
Morvarid Petrochemical Plant,
(Petrochemical Zone No 2 , Pars
Economical Energy Zone, Assaluyeh,
Iran; Phone: +98-7727293035,
Ext: 5086; Email:
ghadyanlou@gmail.com). He holds
an M.Sc. degree in chemical and
environmental engineering from
Islamic Azad University, South Branch of Tehran and a
B.Sc. in chemical engineering and the gas industries from
Islamic Azad University of Omidea (Khuzestan, Iran).
Ali Vatani is an associate professor
in the School of Chemical
Engineering, College of Engineering
at the University of Tehran
(Enghelab Ave., Tehran, Iran;
Phone: +98-21- 66461024;
Email: avatani@ut.ac.ir). Among
the many lecture courses he offers
are those dealing with oil-and-gas,
petrochemicals, gas processing
and distribution and two-phase fluid mechanics He holds
B.Sc. and M.Sc. degrees from the University of Tehran,
and a Ph.D. from the University of Leeds (U.K.).
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