(161c) Transfer Line Exchangers in Ethylene Furnaces: Operating and Reliability Experience

Modern transfer line exchangers for ethylene cracking furnaces are either of multiple tube or linear exchanger design. The choice of the selected concept depends mostly on the cracking furnace outlet tube arrangement. Transfer line exchangers are highly thermally loaded and therefore require special design concepts to meet process needs. Continuous development taking into account operating history and experience in combination with research and development efforts are important to meet operators' requirements for long service life and reliability. Transfer line exchangers are connected either by flange or welded joints to the radiant coil outlets. Areas exposed to hot process gas but not cooled by water are internally insulated to guarantee moderate metal temperatures and low thermal loads. Parts without internal insulation are insulated on the outside for personnel protection and to minimize heat losses. The presentation will cover critical points in the operation of TLE's, their impact on the reliability and will highlight experiences with the different transfer line exchanger types.