BORSIG Process Heat Exchanger GmbH
More than 50 years of

„Tunnelflow“ Transfer Line Exchanger (shell & tube design)

The BORSIG “tunnelflow” transfer line exchangers rapidly cool down the cracked gas in ethylene plants.

A transfer line exchanger system consists of one cooler with a steam drum and riser and down comer line . It can be arranged vertical or horizontal into the plant.

We supply “tunnelflow” transfer line exchangers for every required mass flow and heat duty.

„Tunnelflow“ Transfer Line Exchanger
„Tunnelflow“ Transfer Line Exchanger

The design has the following benefits:

  • Tube bundle heat exchanger - large water volume, a robust shell around the bundle tubes
  • Thin reinforced tube sheet at the gas inlet for very efficient cooling - low material temperatures, low tension
  • Special tube-to-tube sheet welded seams - no sharp edges, full penetration weld
  • Guided water flow with a high water velocity across the thin inlet tube sheet - no deposits can settle down
  • No limits for the operating pressure on the water/ steam side
  • Only one or two risers/ down comers per exchanger
  • 0.5 Mo material - no post weld heat treatment required after welding process
  • Uniformly gas distribution of the gas to all bundle tubes due to special trumped shape design of inlet channel
  • Optional Erosion-protection shield - protects the inlet tube sheet against erosion
  • Possibility of blowdown via quick open valve
  • Easy maintenance



Ethylene is the basic product for the fabrication of plastics. Ethylene (C2H4) and some other byproducts like propylene are produced by thermal cracking of hydrocarbons in pyrolysis furnaces in the presence of steam. Predominantly ethane, naphtha and other mineral oil fractions are used as feedstocks.