Thermal coupling opportunities for floating natural gas liquefaction plants

•Thermal coupling for NGL fractionation in floating natural gas liquefaction plants.•A special dividing wall column (DS-DWC) saves energy, capital, plot area and weight.•A thermally coupled direct sequence (TCDS) with cryogenic condensation of ethane.•TCDS is a retrofit option for existing sequences of conventional distillation columns. In order to meet current carbon dioxide emissions reduction challenges, natural gas processing and refining industries have to find new ways to minimize energy requirements. Building on foundations laid down in a preceding effort, this paper shows that this could be achieved in a cost-effective way for the distillation section in natural gas liquids fractionation plants. A conventional demethanizer column, combined with either a thermally coupled direct sequence of deethanizer and propane–butane recovery columns or a dividing wall column, produces significant savings in capital and hot utilities costs as compared to conventional distillation with a direct sequence, without any temperature penalty on cold utilities side. The choice between available options will largely depend on important process considerations that may differ for offshore and onshore plants and specific site requirements.