Active Bypass Design for Optimal Operation of Heat Exchanger Networks

Optimal operation space of heat exchanger networks (HENs) is largely influenced by either their hard constraints or limitation of operation margin when a bypass or utility unit is selected as a manipulated variable (MV), but previous methods generally focused on solving the identification of inactive bypasses and active pairings in sequence, wherein the inactive bypasses features hard constraints or even saturation during adjustment, and these can result in overly conservative solutions. To improve the operation space of HENs, this paper proposes a feasible solution of bypass design to simultaneously find the inactive bypasses and their active pairings with auxiliary bypasses. In a given network containing disturbance information, they are expressed by mixed integer non-linear programming (MINLP) with the objective function providing minimum control action and utility consumption. A case is subsequently studied to analyse the feasibility of the above framework. The principal orientations and contents of the proposed method lay the groundwork for the integration of HENs synthesis and control.