MINLP SOLUTION FOR AN OPTIMAL ISOTOPE-SEPARATION SYSTEM

This paper deals with designing of cryogenic distillation systems for the separation of hydrogen isotopes in a thermonuclear fusion process. The design must minimize the tritium inventory in the distillation co lumns and satisfy the separation requirements. This induces the optimi zation of both the structure and the operating conditions of the colum ns. Such a problem is solved by use of a Mixed-Integer NonLinear Progr amming (MINLP) tool coupled to a process simulator. The MINLP procedur e is based on the iterative and alternative treatment of two subproble ms : a NLP problem which is solved by a reduced-gradient method, and a MILP problem, solved with a Branch and Bound method coupled to a simp lexe. The formulation of the problem and the choice of an appropriate superstructure are here detailed, and results are finally presented, c oncerning the optimal design of a specific isotope separation system.