Introducing a hybrid oxy-fuel power generation and natural gas/ carbon dioxide liquefaction process with thermodynamic and economic analysis

Abstract

Oxy-fuel power generation and carbon dioxide capture as a downstream process is a near-zero emission energy system. The captured carbon dioxide can be liquefied but carbon dioxide liquefaction process needs considerable amounts of energy. Liquefied natural gas plays an important role in natural gas transportation. However, its production is known as an energy-intensive process. In this study, a novel integrated process of liquefied natural gas production, oxy-fuel electrical power generation cycle and cryogenic carbon dioxide capture and liquefaction is proposed and investigated by chemical process simulators. Effective operating parameters of the process and its components are thermodynamically analyzed. In this regard, effect of the turbine inlet temperature and pressure ratio, oxidant, oxygen and propane flow rates on the power generation and electrical efficiency of the oxy-fuel cycle, carbon dioxide liquefaction temperature and pressure and liquefied natural gas production rate are examined. The obtained results indicate that, the proposed process can be used to design of the actual plants with optimal operating performance. Specific power consumption of the liquefied natural gas process is about of 0.281 kWh/kg LNG. Also, to verify the accuracy of the process performance, the exergy analysis was performed for the process and all of its components. Through this analysis the exergy efficiency of the oxyfuel power cycle and natural gas liquefaction process are gained 69% and 51% respectively. Economic analysis of the process shows that prime cost of the product and period of return are 0.299US$/kgLNG and 2.392 years respectively.