Convert hot wall FCCU lines to cold wall design

Many refiners are seeing increasing financial advantages in raising the operating temperatures of their fluid catalytic cracking units (FCCU). Increasing demands for higher octane gasolines, the need to use heavier feedstocks and the availability of new, more tolerant and active catalysts for increased yields are forcing refiners to look at operating their units at higher temperatures. High temperature operation, however, has been a major cause of failure of FCCU equipment resulting in shorter run lengths, higher maintenance costs and increased downtime. Many operating FCC units were designed and built years ago when design temperatures were lower than those required for today's optimum operation. In a significant number of these units the catalyst transfer lines were designed for hot wall operation where the line wall temperatures are close to the fluid operating temperature. Hot wall transfer lines traditionally have required significant maintenance and may be one of the bottlenecks in upgrading some FCC units to higher operating temperatures. High maintenance of hot wall transfer lines is one of the major reasons owners are changing to cold wall designs.