Evaluation of an Integrated Cryogenic Natural Gas Process with the Aid of Advanced Exergy and Exergoeconomic Analyses

In this study, an integrated structure of the air separation unit, natural gas liquids recovery equipped with nitrogen removal unit is developed. In this regard, advanced exergy and exergoeconomic analyses are used to examine the irreversibility, possible improvements and the cost of the inefficiencies of the process. The exergy analysis presents information on the origin of the irreversibility as well as the amount of irreversibility of each component. The results of advanced exergy analysis show that HX۲, HX۳, C۱, C۲, C۳, AC۱, AC۳ equipment have the highest amount of the irreversibility due to endogenous exergy destruction, whereas the highest amount of the irreversibility in the rest of the equipment is because of exogenous exergy destruction. Furthermore, avoidable exergy destruction of equipment is more than the unavoidable exergy destruction in the C۱, C۲, and C۳. This issue shows that with the improvement of the efficiency of the equipment, it is feasible to reduce the irreversibility of these systems. In addition, the results of advanced exergoeconomic analysis show that the priority to improve the performance of the system should be devoted to the HX۲, HX۳, C۱, C۳, AC۱, AC۳ equipment, respectively. The AC۱ air cooler and the C۳ compressor have the highest amounts of investment cost of avoidable endogenous exergy destruction, respectively. The heat exchanger HX۳ and air cooler AC۲ and AC۳ have the lowest investment cost of avoidable endogenous exergy destruction.

Keywords:

Natural gas liquids , non-standard nitrogen separation , air separation unit , Advanced exergy analysis , Advanced exergoeconomic analysis