In this work, heat pumping (e.g. heat transfer to the reboiler from the compressed overhead vapour of a distillation column) has been considered in the design of separation sequences. It is illustrated how heat pumping exploits the trade-offs between separation operating conditions and heat integration opportunities. The work builds on previous research on distillation sequence synthesis and design, with and without heat integration. The approach includes simple and complex distillation configurations, various heat pumping configurations, as well as direct heat integration options.
The sequence synthesis problem is formulated as an optimisation problem that is solved using a genetic algorithm (a stochastic optimisation technique). Case studies consider the separation of ethylene cracker products and of other mixtures of light hydrocarbons. These case studies illustrate that the separation sequences generated by this approach can achieve significant reductions in costs, compared to conventional sequence and column configurations.