Optimum mass integration strategies for condensation and allocation of multicomponent VOCs

Abstract

Multicomponent volatile organic compounds (VOCs) are among the most important species employed in the process industry. Their recovery and allocation, therefore, are critical tasks in many facilities. A key VOC recovery technology is condensation. This paper introduces a systematic procedure for the optimal design of condensation, mixing and routing of multicomponent VOCs. Mass integration strategies are employed as a holistic framework for addressing the problem. First, a mixed integer nonlinear program is developed to solve the problem. Because of the non-convexity of the problem coupled with the need to solve an inner minimization problem, a global optimization procedure is developed. This procedure is based on exploiting problem properties gained by insights, active constraint strategies and decomposition techniques. Furthermore, the solution strategy allows the use of non-ideal vapor liquid equilibrium calculations outside the optimization problem thereby significantly simplifying the calculations while still maintaining the rigor of the results. Using these concepts, the seemingly complicated design task is reduced to a far more tractable problem which is solved globally. A case study is presented to demonstrate the broad applicability and potential benefits of the approach along with its global optimization solution strategies.