Basic design and thermodynamic analysis of a high helium content natural gas-fuel cell power plant

Abstract

In this paper, a new developed integrated process for the production of power, helium, and liquefied natural gas (LNG) is proposed and analyzed. The proposed integrated process is composed of the following subsystems: helium recovery and LNG production unit, molten carbonate fuel cell (MCFC), absorption refrigeration system (ARS), as well as the steam power plant. Natural gas enters the helium recovery unit, in which crude helium and LNG are produced, and then, methane-rich natural gas with a higher heating value enters the MCFC cycle, which is responsible for generating power and supplying required heat duty of the system. The produced cooling in the ARS unit is also introduced to the helium recovery cycle to provide its necessary cooling. A comprehensive comparative study is employed to assess process performance. In addition, a sensitivity analysis is performed to investigate the effect of the main operating parameters such as current density, fuel utilization factor, fuel cell temperature, and feed flow rate on process efficiency. Based on the energy analysis results, the electrical efficiency of MCFC and the overall thermal efficiency of the process are 42.01% and 94.91%, respectively. Also, the integrated system produces helium and LNG, with helium extraction rate of 91.42% and specific power consumption (SPC) of 0.2086 kWh/kg LNG, respectively, in conjunction with 4793 MW net power.