Cracker Feedstock Changes: From Naphtha to Ethane Cracker

Driven by the US shale gas boom, cracking ethane to ethylene became more attractive than cracking liquid feedstocks in the last years. Therefore owners of liquid crackers envisage to minimize liquid feedstocks or even to fully replace by ethane. The present paper briefly describes process unit by process unit which challenges in process engineering have to be met when changing from liquid to gaseous feedstocks.

Concepts and associated modifications in two key process units are explained in more detail:

• Quench oil column unit: the lack of liquid cracking products when cracking gas has to be compensated by importing hydrocarbons with similar boiling range and aromaticity.

• Demethanizer unit: to compensate the lack of methane when changing from liquid to gas cracking, several concepts like addition of expander/booster units or integration of an additional open LP methane refrigerant cycle are proposed.