The gas produced by cracking, which leaves the furnace at a temperature of around 850°C (1500°F), must be cooled down rapidly (quenching) after leaving the reaction zone of the furnace in order to prevent secondary reactions and to stabilize the gas composition in order to obtain the optimum product yield. In all modern ethylene processes this rapid cooling of the cracked gas is done with quench coolers (also known as transfer line exchangers or TLEs) thereby producing high pressure steam. The quench cooler system is located downstream to the cracking furnace and consists of one or more parallel coolers per furnace cell. The coolers are connected by riser and downcomer piping with one common, elevated steam drum. BORSIG “Tunnelflow” Transfer Line Exchangers (quench coolers) are the result of more than 40 years experience. A state of the art, tailored-to-practice design, modern manufacturing and testing methods and the specialized knowledge of the BORSIG Group ensures that high-quality quench coolers are produced that meets today’s requirements with regards to mechanical and operational reliability. The strengths and sound workmanship coupled with uncompromising performance earned the company a leading global position, have gained the BORSIG “Tunnelflow” quench cooler a high reputation at home and abroad.