Energy efficiency of the cold train of an ethylene cracker

Ethylene cracking technology providers have continuously worked to improve the energy efficiency of their cracker designs. As a result, current designs are very complex and highly heat integrated. Although technology vendors claim that the three different designs for the cold section of a steam cracker, i. e. demethanizer first and the depropanizer first, have roughly the same energy efficiency, simulation results obtained with Aspen show that significant differences exist. For a naphtra steam cracker with an annual ethylene production capacity of 10(6) ton ethylene the demethanizer first design is slightly more energy efficient than a depropanizer or a deethanizer first design. Using front-end hydrogenation in combination with a demethanizer first cold train allows further reduction of the energy consumption per ton ethylene produced. However front-end hydrogenation has a disadvantage over backend configurations in that some valuable products such as butadiene can be partially lost.