INTRODUCTION

Fluid catalytic cracking (FCC) technology is a technology with more than 60 years of commercial operating experience. The process is used to convert higher-molecular-weight hydrocarbons to lighter, more valuable products through contact with a powdered catalyst at appropriate conditions. Historically, the primary purpose of the FCC process has been to produce gasoline, distillate, and C ₃/C ₄ olefins from low-value excess refinery gas oils and heavier refinery streams. FCC is often the heart of a modern refinery because of its adaptability to changing feedstocks and product demands and because of high margins that exist between the FCC feedstocks and converted FCC products. As oil refining has evolved over the last 60 years, the FCC process has evolved with it, meeting the challenges of cracking heavier, more contaminated feedstocks, increasing operating flexibility, accommodating environmental legislation, and maximizing reliability.

The FCC unit continuously circulates a fluidized zeolite catalyst that allows rapid cracking reactions to occur in the vapor phase. The KBR Orthoflow FCC unit (Fig. 3.1.1) consists of a stacked disengager-regenerator system that minimizes plot space requirements. The cracking reactions are carried out in an up-flowing vertical reactor-riser in which a liquid oil stream contacts hot powdered catalyst. The oil vaporizes and cracks to...