Sensitivity analysis, economic optimization, and configuration design of mixed refrigerant cycles by NLP techniques

•Having presented a systematic method, the authors acquired optimized design configuration by non-linear programming techniques.•Economic optimization was developed through a combination of multi-stream exchanger design and optimized operation parameters.•Perturbations method was employed to undertake the sensitivity analysis.

Over the past decades, increasing attention has been paid to optimal design and operation of energy intensive industries. The purpose of this paper is to present a systematic method based on a combination of mathematical methods and thermodynamic viewpoints to acquire optimized design configuration by non-linear programming techniques. Economic optimization was developed through a combination of multi-stream exchanger design and optimized operation parameters. Next, perturbations method was applied for the sensitivity analysis in the discussed refrigeration cycles in the paper. Ultimately, the results showed the one-stage cascade of mixed refrigerant refrigeration cycle (MRRC) as the best option to replace pure ethylene cycle in the olefin plant of Tabriz Petrochemical Complex.