Thermodynamic and Economic Analysis of an Ammonia Synthesis Process Integrating Liquified Natural Gas Cold Energy with Carbon Capture and Storage

Abstract

Ammonia, as a bulk chemical, is widely used in fertilizers and fuels and is also a promising hydrogen carrier. Aiming at reducing the high energy consumption of the ammonia synthesis process, this study innovatively proposed a low-carbon ammonia synthesis process based on the cold energy utilization of liquified natural gas regasification. In this process, the cold energy released from the regasification of liquified natural gas was used as the refrigeration source of the air separation unit and carbon capture and storage unit, which improves the comprehensive energy utilization efficiency of the whole process of synthetic ammonia. Based on Aspen Plus simulations, the process economy and exergy were comprehensively analyzed. The total efficiency of the low-carbon ammonia synthesis process was 42.69%, of which the ammonia production capacity was 35.07 t/h, and the total capital investment of the integrated process was 3.4 × 107 USD, and the product cost was 387.86 USD. Compared with three different ammonia plants, the levelized cost of ammonia in the low-carbon ammonia synthesis process was reduced to 324.03 USD/ton. The proposed process can well solve the problems of high energy consumption in the ammonia synthesis process and provide a valuable production route for the low-carbon ammonia synthesis process.