CAPITULO I. ANTECEDENTES
1.1. Origen y Naturaleza de las contribuciones
44SEPTEMBER 2012 | HydrocarbonProcessing.com
Refining Developments
endpoint on octane, calculated from narrow-boiling-range oc- tane data for three different FCC situations operating with a
variety of feedstocks, catalysts and operating conditions.10
In many cases, seasonal demand swings are accommodated with changes in the FCC gasoline cutpoint, with no change to the true (430°F) FCC conversion level, as this strategy works to preserve the LPG production, octane and total liquid vol- ume associated with the higher-conversion operations.
Crude distillation. Another common practice is maximiz-
ing diesel production from the crude distillation processes so that losses of potential diesel to the FCC feed are minimized. There are intermediate swing cuts from some crude distillation operations that can be routed to the FCC unit when gasoline is demanded, and routed to diesel production when the objec-
tive is maximizing diesel. As a side benefit, keeping the diesel
out of the FCC feed also improves FCC gasoline octane.11
Pilot plant data have shown that, in moderate or high-se- verity FCC operations, most of the straight-run diesel will be converted to gasoline and lighter products with only 20%–30% leaving the FCC in the LCO product. The data have also shown that the LCO made from the distillate will have cetane values 10 to 15 numbers below that of the distillate feed, but still higher than that of typical FCC LCO.
Beyond standard operating adjustments, there may be in- vestment opportunities in crude distillation hardware that can achieve a sharper separation between the diesel product and FCC feed streams, reducing the loss of potential diesel to the FCC feed.
A survey of over 100 refineries indicated that FCC feed typi-
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TABLE 3. Examples of calculated incremental diesel production
Base case Additional diesel recovery options
Atmospheric tower revamp
Add standard diesel draw to VDU
Add high-recovery diesel draw to VDU
Install gas oil tower in front of VDU
Install vacuum prefl ash tower in front of VDU Install LVGO splitter tower Incremental diesel, vol% of crude 1.3 3.0* 3.2* 2.2* 2.3* 3.4* Number of additional fractionation stages between diesel and gasoil
5 2 6 4 4 12
*Incremental yield of selected option relative to base case
Hydrocarbon Processing | SEPTEMBER 201245
Refining Developments
cally contains between 10 vol% and 15 vol% of material, mostly
diesel, boiling below 650°F.12 In environments where gasoline
production is maximized, the loss of diesel to the FCC unit has little negative impact. However, if the objective is diesel maxi- mization, better crude fractionation efficiency between diesel and FCC feed can be economically justified.
There are a number of ways to reduce the loss of virgin die-
sel to the FCC feed.13 Some of these options are listed below:
• Revamp the atmospheric distillation column to increase the degree of fractionation between the diesel and atmospheric gasoil products
• Revamp the vacuum column to produce a diesel product • Add a gasoil tower or a vacuum preflash tower between the atmospheric and vacuum distillation columns, and recover diesel from the vacuum tower feedstock
• Add a splitter column to process the light vacuum gasoil (LGVO) and produce a diesel stream.
TABLE 3 shows examples of calculated incremental diesel
production that were reported for some of these options.13
The best options for a given refinery are a function of the site
specifics of the application, but the data in TABLE 3 indicate
the magnitude of diesel production increases that are possible.
Part 2 of this article, to be published in October, will ex-
plore the selection of FCC catalysts, methods for hydropro- cessing LCO, and the production of diesel fuel from FCC by- products, among other topics.
LITERATURE CITED
1 Eskew, B., “The Diesel Challenge and Other Issues Facing US Refiners,” NPRA
Q&A and Technology Forum, Champions Gate, Florida, October 2008.
2 Flinn, N. and S. P. Torrisi Jr., “LCO Upgrading Options: From Simple to
Progressive Solutions,” Russia and CIS Refining Technology Conference and Exhibition, Moscow, Russia, September 2008.
3 Unzelman, G. H., “Potential Impact of Cracking on Diesel Fuel Quality,”
Katalistiks Fourth Annual Fluid Cat Cracking Symposium, Amsterdam, The Netherlands, May 1983.
4 Hunt, D., R. Hu, H. Ma, L. Langan and W.-C. Cheng, “Recycle Strategies and
MIDAS-300® for Maximizing FCC Light Cycle Oil,” Catalagram 105, W. R. Grace & Co., Spring 2009.
5 Peterson, R. B., C. Santner and M. Tallman, US Patent No. 7,153,479.
6 Gilbert, M. F., M. J. Tallman, W. C. Petterson and P. K. Niccum, “Light Olefin
Production from SUPERFLEXSM and MAXOFINTM FCC Technologies,” ARTC
Petrochemical Conference, Malaysia, February 2001.
7 Miller, R., T. Johnson, C. Santner, A. Avidan and D. Johnson, “FCC Reactor
Product-Catalyst Separation—Ten Years of Commercial Experience with Closed Cyclones,” NPRA Annual Meeting, San Francisco, California, March 1995.
8 Pillai, R. and P. K. Niccum, “FCC Catalyst Coolers Open Window to Increased
Propylene,” Grace Davison FCC Conference, Munich, Germany, September 2011.
9 Melin, M., C. Baillie and G. McElhiney, “Salt Deposition in FCC Gas
Concentration Units,” Catalagram 107, W. R. Grace & Co., 2010.
10 Akbar, M., B. Claverin, M. Borley and H. Otto, “Some Experiences with FCC
Octane Enhancement,” Ketjen Catalysts Symposium, Scheveningen, The Netherlands, May 1986.
11 Fletcher, R., Meeting Transcript, 1997 NPRA Q&A Session: Refining and
Petrochemical Technology, New Orleans, Louisiana, October 1997.
12 Sloley, A. W., “FCC Network News,” Refinery Process Services Inc., Vol. 35, January 2010. 13 Sloley, A. W., “Increase diesel recovery,” Hydrocarbon Processing, June 2008.
PHILLIP NICCUM joined KBR Inc.’s fluid catalytic cracking (FCC) team in 1989 following nine years of FCC-related work for a major oil company. Since that time, he has held various FCC-related positions at KBR Inc., including process engineering manager, technology manager, chief technology engineer of FCC, and now director of FCC technology. Mr. Niccum’s professional activities have included engineering management, process engineering, project engineering, marketing, and licensing. Areas of technical strength include FCC unit design, precommissioning and startup, troubleshooting and economic optimization of FCC unit operations.
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