Conventional and advanced exergoeconomic analyses applied to ethylene refrigeration system of an existing olefin plant

Ethylene refrigeration system of a light olefins production plant was investigated using the conventional and advanced exergoeconomic analyses. In advanced analysis, investment and exergy destruction costs of system components are divided into endogenous/exogenous and avoidable/unavoidable parts to improve our knowledge about the refrigeration system. Results of the exergoeconomic analysis represent that the total cost of column T-1 (1217.67 $/h), compressor C-3 (864.88 $/h), compressor C-2 (250.43 $/h) and multi stream heat exchanger MSHE-1 (154.19 $/h) are larger than other components. Results of the advanced exergoeconomic analysis reveal that most of the total costs of components are endogenous and can be reduced only for column T-1 and compressor C-3. With increasing the efficiency of these two components, investment and exergy destruction costs has been decreased (1381.74 $/h). Large amounts of endogenous exergy destruction cost of components represent that the interactions between the components are not a main reason for exergy destruction. Therefore, an appropriate strategy for the enhancement of the system efficiency and profitability is to improve their performance. Based on the above results, column T-1 and compressor C-3 have the highest priority to improve the performance. Sensitivity of the analysis parameters to some important operating variables have also been investigated.