SYNTHESIS AND ANALYSIS OF FLEXIBLE ENERGY RECOVERY NETWORKS (HEAT EXCHANGER)

This thesis considers the problem of synthesis and analysis of flexible energy recovery networks. Firstly, the problem of generating automatically heat exchanger networks configurations for fixed operating conditions that feature minimum investment cost subject to minimum utility cost and fewest number of units is addressed. Based on the (LP) and (MILP) transshipment models for heat integration, a superstructure that has embedded many alternative configurations is proposed. This superstructure, has as units the matches predicted by the (MILP) transshipment model. Many of the implied stream connections in the superstructure are reduced to zero flow with a nonlinear programming formulation, that leads to realistic and practical designs. Theoretical properties as well as implementation aspects of the proposed procedure for the automtic generation of networks are presented.; Next, the problem of synthesizing networks that have the flexibility of coping with prespecified changes in flowrates, inlet temperatures and outlet temperatures in a finite sequence of time periods is considered. A multiperiod version of the mixed integer linear programming (MILP) transshipment model is presented. Based on this model, a systematic procedure is proposed for synthesizing networks that require minimum utility cost for each period of operation and involve the fewest number of units.; For the flexibility analysis of chemical processes, it is shown that by exploiting properties of limiting constraints for flexibility in a design, the Feasibility Test and Flexibility Index problems can be formulated as mixed-integer optimization problems. These formulations do not rely on the assumption that critical parameters are vertices, nor do they require exhaustive vertex searches. Efficient solution strategies and their theoretical properties are analyzed.; Finally, a systematic procedure is presented for the synthesis of flexible heat exchanger networks that involve specified uncertainties in the flowrates and inlet temperatures of the process streams. The problem is decomposed into two stages: prediction of matches, and derivation of the network configuration. At each stage, synthesis techniques are combined with a flexibility analysis to test the feasibility of operation of the design over the specified range of the uncertain parameters. It is shown that special properties can be exploited to efficiently perform the flexibility analysis. (Abstract shortened with permission of author.)...