Exergoeconomic analysis of an LNG integrated - air separation process

An integrated LNG regasification - air separation process is investigated using exergy and exergoeconomic analyses. The objective of developing this integrated process is to lower the calorific value of LNG by mixing regasified LNG with high purity nitrogen, while simultaneously recovering and utilizing valuable cryogenic energy from the LNG during its regasification to minimize the power consumption of the air separation unit (ASU) for nitrogen production. The overall exergy efficiency and exergy destruction of the integrated process are 76.47% and 28.52 MW, respectively, with the compression section causing the most exergy destruction. Further exergoeconomic analysis of the proposed process reveals that the air compressors have the highest capital investment (CI) and operating and maintenance (O&M) cost rates, the pumps for cooling water and LNG have the highest exergoeconomic factors, and the low-pressure column and a multistream heat exchanger have the highest exergy destruction cost rates. A parametric study is also conducted to examine the impact of economic variables including interest rate, plant life, and compressor performance on exergy destruction, CI and O&M cost rates, and exergoeconomic factor. The findings of this study offer valuable insight into the design and optimization of similar integrated processes, with potential benefits for the energy industry.