Optimal synthesis and scheduling of hybrid dynamic/steady-state property integration networks

This paper introduces a new problem in the emerging area of property integration. The problem involves synthesizing a network of property-modifying units and scheduling operating schemes. Data and constraints for the process sources, sinks, and interceptors are given in terms of properties. Sources are process streams to be allocated. Sinks are process units that can accept the sources. Interceptors are new units to be added to the process to intercept the sources and adjust their properties to meet the sink requirements. The interceptors may be steady-state or dynamic units whose performance is expressed in terms of input–output relations for designated properties. In addition to flowrate bounds, the constraints on acceptable feeds to the sinks are described as lower and upper bounds on designated properties. A conceptual framework is first developed to serve as the basis for a mathematical program coordinating the synthesis of the interception and allocation networks as well as the operational scheduling of the system. A source–interception–sink representation is developed to embed structural configurations of interest. The time domain is decomposed into repeating episodes. Within each episode, the interceptors are allowed to modify properties of sources, remain idle, or undergo regeneration. The regeneration process restores the interceptor to its initial condition. A mixed-integer nonlinear programming formulation is developed to minimize the total annualized cost of the system, synthesize the network, and determine its optimal operating schedule. A case study is solved to demonstrate the new problem and the devised solution algorithm.