2 SPRING 2008 SAUDI ARAMCO JOURNAL OF TECHNOLOGY ABSTRACT High-severity fluid catalytic cracking (HS-FCC) is an emerging process for the conversion of heavy oils into lighter hydrocarbon products and light olefins. The HS-FCC project is a partnership in technology innovation from conception to full scale commercialization with Saudi Aramco, King Fahd University of Petroleum & Minerals (KFUPM), Nippon Oil Corporation and Japan Cooperation Center, Petroleum. This technology combines mechanical modifications with conventional fluid catalytic cracking (FCC), including changes in operating conditions and catalyst formulations. The process reaction scheme consists of a down-flow (downer) reactor and regenerator. Other features include a high reaction temperature, short contact time and high catalyst-to-oil ratio. The HS-FCC process has been successfully demonstrated in a 30 barrel per day (BPD) plant at Saudi Aramco’s Ras Tanura refinery and in a 500 BPD cold-flow model at Nippon Oil’s Yokohama refinery. Experimental runs were conducted using various catalysts, additives and feed oils. Pilot plant results demonstrated the advantage of the downer in suppressing back mixing, thus increasing the yield of light olefins and reducing dry gas and coke formation. Using paraffinic crude base vacuum gas oil (VGO), a propylene yield of 25 wt% was obtained under HS-FCC reaction conditions. INTRODUCTION Fluid catalytic cracking (FCC) continues to be the dominant conversion process for gasoline and light olefins production with a global capacity of 14.2 million BPD. The growing demand for naphtha and propylene is just one of the reasons why worldwide capacity continues to increase. While refiners are under pressure to process heavier crude, the FCC product slate is increasingly shifting towards light olefins production (mainly propylene). Currently, FCC supplies 30% of the world’s propylene, and the remaining is co-produced from ethylene steam cracking of naphtha or other feedstocks. Other sources of propylene in the refinery arise primarily from visbreaking and coking. Increasing the yield of the valuable light olefins, especially propylene and butylenes remain a major challenge for many refiners worldwide. The processing of propylene to polypropylene (PP) improves refinery margins and increases revenues because of the high value of PP 1, 2 . Increasing the yield of the valuable light olefins, especially propylene and butylene, remains a major challenge for many refiners. As global petrochemical demand for propylene continues to grow, opportunities for improved production routes will emerge. Propylene is used as a feedstock for a wide range of polymers, product intermediates and chemicals. Major propylene derivatives include polypropylene, acrylonitrile, propylene oxide, oxo-alcohols and cumene, and account for almost 90% of global propylene demand. The processing of propylene to polypropylene improves refinery margins and increases revenues because of the high value of polypropylene. Obviously, a need for an economical propylene generating process is required to meet these demands for light olefins (C 3 through C 5 ). Conventional FCC units typically produce about 3 wt% - 6 wt% propylene depending on feed type, operating conditions, and type of catalyst. Despite the options available to increase propylene yields and yields of other light olefins, intense research activity in this field is still being conducted. These options include the use of high-selective FCC catalysts, ZSM-5 olefin boosting catalyst additives, high-severity operation (higher reaction temperature), reprocessing (recycle) of FCC naphtha, and emerging propylene-oriented FCC processes. ZSM-5 additives can increase propylene to about 8 wt% while improvements in FCC catalysts, process design, hardware and operation severity can boost propylene yield from 5% to 25% or higher. Increasing the yield of the valuable light olefins, especially propylene and butylenes remain a major challenge for many refiners worldwide. This need for increased propylene production from FCC processes is key to future refinery development. Development of a Novel Refinery Process: From Laboratory Experiments to Commercial Applications Authors: Mohammad H. Al-Tayyar, Allan B. Fox, Christopher F. Dean, Yuichiro Fujiyama, Toshiaki Okuhara, Dr. Abdullah M. Aitani and Mian Rahat Saeed Table 1. Features of the HS-FCC process Down-Flow Reactor Short Contact Time High Catalyst/ Oil Ratio Minimizes back-mixing Reduces thermal cracking Compensates reduced conversion Reduces undesirable byproducts Reduces undesirable successive reactions Enhances catalytic cracking