Cost-Optimal Heat Exchanger Network Synthesis Based on a Flexible Cost Functions Framework

Abstract

In this article an approach to incorporate a flexible cost functions framework into the cost-optimal design of heat exchanger networks (HENs) is presented. This framework allows the definition of different cost functions for each connection of heat source and sink independent of process stream or utility stream. Therefore, it is possible to use match-based individual factors to account for different fluid properties and resulting engineering costs. Layout-based factors for piping and pumping costs play an important role here as cost driver. The optimization of the resulting complex mixed integer nonlinear programming (MINLP) problem is solved with a genetic algorithm coupled with deterministic local optimization techniques. In order to show the functionality of the chosen approach one well studied HEN synthesis example from literature for direct heat integration is studied with standard cost functions and also considering additional piping costs. Another example is presented which incorporates indirect heat integration and related pumping and piping costs. The versatile applicability of the chosen approach is shown. The results represent designs with lower total annual costs (TAC) compared to literature.

Modified Mixed-Integer Linear Programming Formulation Implemented in Microsoft Excel to Synthesize a Heat Exchanger Network with Multiple Utilities to Compare Process Flowsheets

“…In the case of the match i-BFW, contrasting the heat of i streams per interval and BFW heat from the Grand Composite Curve, the U ij values were determined. Equation (7) guarantees that the utility heat introduced at all k intervals equals the value determined by the TI method or the Grand Composite Curve [1]. In this case, one equation per hot utility must be introduced into the m-MILP algorithm.…”

“…Likewise, Sun et al [6] communicated a stage-wise SST accounting for the generation and absorption processes from a compression-absorption cascade refrigeration system. Also, Rathjens and Fieg [7] used a genetic algorithm and deterministic local optimization techniques for solving the SST. In addition, the HEN obtention by solving a MINLP using results from the resolution of mixed-integer linear programming (MILP) problems of the same process-stream data has been claimed by Nemet et al [8], with optimization of the temperatures, flowrates, and areas associated with each match by Caballero et al [9].…”

Cost Reduction of Fluid Catalytic Cracking Unit in Kaduna Refining and Petrochemical Company using Pinch Technology

“…Here, the heat exchange was assumed to be "vertical" (pure counter-current heat exchange). Therefore, the surface area for each section ( ) was calculated using the following widely accepted heat exchanger equation defined in Rathjens and Fieg (2019)…”

Towards Efficient and Clean Process Integration: Utilisation of Renewable Resources and Energy-Saving Technologies

“…Jamaluddin et al [84] attempt to deal with the Heat and power at a total site by a trigeneration system and reached an extension of the methodology. Another contribution to a most studied issue dealing with this topic a cost-optimal heat exchanger network synthesis enhanced with flexible cost function network was presented by Rathjens et al [85]. The utilisation of an air-PCM heat exchanger in passive cooling of buildings was presented by a team from the VUT Brno Energy Institute [86].…”