Key Role of Reactor Internals in Hydroprocessing of Oil Fractions Anton Alvarez, † Sergio Ramı ´rez, † Jorge Ancheyta,* ,†,‡ and Luis M. Rodrı ´guez § Instituto Mexicano del Petro ´ leo, Eje Central La ´ zaro Ca ´ rdenas 152, Col. San Bartolo Atepehuacan, Me ´ xico D.F. 07730, Escuela Superior de Ingenierı ´a Quı ´mica e Industrias ExtractiVas (ESIQIE-IPN), Me ´ xico D.F. 07738, Pemex Refinacio ´ n, Gerencia de Ing. de Procesos, Subdireccio ´ n de Produccio ´ n. Me ´ xico D.F. ReceiVed December 21, 2006. ReVised Manuscript ReceiVed February 12, 2007 Several aspects of fixed-bed hydroprocessing reactor internals have been reviewed. Fundamentals of conventional and modern reactor internal hardware such as distributor trays and quench boxes are described, and examples of commercial systems are presented. The methods for detecting maldistribution and cases of successful revamping are also discussed. It was recognized that properly designed reactor internals improve substantially unit performance by increasing product quality and extending catalyst cycle length. 1. Introduction Most of the fixed-bed hydroprocessing reactors currently in operation in worldwide petroleum refineries have been built and designed over the past 30 years. 1 Traditionally, it has been of common practice that when refiners acquire hydroprocessing technologies from licensors reactor internal hardware design is also included. 2 New design of reactor internals along with the constant catalyst improvements has allowed these units to maintain an acceptable performance to meet the more stringent fuel specifications keeping catalyst cycle life and run length within economically attractive limits. However, those units have been experiencing underperformance with the increasing supply of heavier oils to the refineries and the tightening environmental legislations. The problems of constant changes of feedstock properties and product quality were partially solved with increases of reaction severity, which reduced considerably the catalyst cycle life due to enhanced catalyst deactivation. Mechanical constrains in reactor design and product demand were also other problems that refiners had to face when trying to increase reactor temperature and reduce feed flow rate (i.e., decrease space velocity), respectively. In addition, excessive pressure drops were present due to fouling caused by solids contained in the feed (iron scale, salts, coke fines, etc.) and reaction products (coke and metals). 3 All these problems drastically diminished the length of run due to premature shut downs required for replacing the catalyst with a consequent negative impact on the overall economics of the process and refinery. 4 Over the years, many strategies have been proposed to meet the product specifications dictated by the clean fuels challenge and at the same time to keep the catalyst cycle life at acceptable levels. Those strategies are based on the development of new highly active catalysts, tailoring reaction conditions (e.g., temperature, liquid-hourly space velocity (LHSV), hydrogen partial pressure), and designing new reactor configurations (e.g., multibed reactors with interstage quenching, reactors in series, and counterflow reactors); 5-7 for fouling abatement, improved procedures for catalyst loading, 8,9 low activity mesoporous materials, and graded bed designs were developed. 10 Extensive overviews and study cases of such strategies applied to the production of ultralow sulfur diesel via hydroprocessing have been presented over the past few years. 11-16 Figure 1 shows that, in a typical hydrodesulfurization (HDS) unit producing diesel with 2500 ppmw sulfur with a catalyst cycle life of more than 3 years, an increase of reaction temperature for achieving sulfur concentrations of ∼50 ppmw will reduce the catalyst cycle life by a factor of at least 3 17 or will require more than 4 times the original catalyst volume in order to keep constant the original catalyst cycle life. 12 This example gives a clear idea about how expensive modifications of current processes may be in order to produce environmental friendly fuels. All these studies agree that improving catalyst performance and maximizing its volume * Fax: (01-55) 9175-8429. E-mail: jancheyt@imp.mx. † Instituto Mexicano del Petro ´leo. ‡ Escuela Superior de Ingenierı ´a Quı ´mica e Industrias Extractivas (ESIQIE-IPN). § Pemex Refinacio ´n. (1) Swain, J.; Zonnevylle, M. Are You Really Getting the Most from Your Hydroprocessing Reactors? Presented at the European Technology Conference, Rome, November 15, 2000. (2) Jacobs, G. E.; Krenzke, L. D. Insights on Reactor Internals for ULSD - Performance of Existing New Hardware. In Proceedings of the NPRA Annual Meeting, San Antonio, TX, March 23-25, 2003; AM-03-92. (3) Chou, T. Pet. Technol. Q. 2004, 4, 79-85. (4) Sie, S. T. Appl. Catal. A 2001, 212, 129-151. (5) Sie, S. T. Fuel Proc. Technol. 1999, 61, 149-171. (6) Knudsen, K. G.; Cooper, B. H.; Topsøe, H. Appl. Catal. A 1999, 189, 205-215. (7) Song, C. Catal. Today 2003, 86, 211-263. (8) Sanford, E. C.; Kirchen, R. Oil Gas J. 1988, December 19, 35-41. (9) Criterion Catalyst and Technologies. Technical Bulletin: Hydrotreat- ing Catalyst Reactor Loading Guidelines. http://www.criterioncataysts.com (accessed Oct 2006). (10) Haldor Topsøe. Brochure: Pressure Drop Control. http://www.top- soe.com (accessed Oct 2006). (11) Hamilton, G. L.; Van der Linde, B.; DiCamillo, D. Hydrotreating Revamp Options for Improved Quality Diesel via Cocurrent/Countercurrent Reactor Systems. Presented at the AICHE Spring National Meeting, Atlanta, Georgia, March 5-9, 2000. (12) Bingham, E.; Christensen, P. Revamping HDS Units to Meet High Quality Diesel Specifications. Presented at the Asian Pacific Refining Technology Conference, Kuala Lumpur, Malaysia, March 8-10, 2000. (13) Bharvani, R. R.; Henderson, R. S. Hydrocarbon Process. 2002, 81, 61-64. (14) Torrisi, S.; DiCamillo, D.; Street, R.; Remans, T.; Svendsen, J. Proven Best Practices for ULSD Production, AM-02-35. In Proceedings of the NPRA Annual Meeting, San Antonio, TX, March 17-19, 2002; AM- 02-35. (15) Palmer, R. E.; Torrisi, S. Pet. Technol. Q. 2003, ReVamps, 15-18. (16) Turner, J.; Reisdorf, M. Hydrocarbon Process. 2004, March. (17) Yeary, D. L.; Wrisberg, J.; Moyse, M. Hydrocarbon Eng. 1997, September, 25-29. 1731 Energy & Fuels 2007, 21, 1731-1740 10.1021/ef060650+ CCC: $37.00 © 2007 American Chemical Society Published on Web 04/05/2007