OVERALL PERFORMANCE OF H_2/O_2 CYCLE POWER PLANTS BASED ON STEAM-METHANE REFORMING

摘要

In this paper the overall performance of a H_2/O_2 cycle has been evaluated. This typology of power plants requires a material and energetic integration with hydrogen and oxygen production systems. The steam-methane reforming, for the hydrogen-rich fuel production, and the cryogenic air separation, for the oxidiser production, have been investigated, quantifying all their thermal and mechanical requirements. At first, the thermodynamic performance of this cycle has been evaluated, considering the presence of incondensable gases, owing to the processes that provide H_2 from fossil fuels and O_2 from air. Then, the power plant has been integrated with the oxidiser and fuel production plants as well as with the fuel compression section. Including all the material and energetic flows, the overall performance has been evaluated. The final result is not very encouraging: in fact, even if the H_2/O_2 cycle has relevant thermodynamic performance if the energetic requirements for oxygen and hydrogen productions are neglected - the efficiency is over 62% -, the overall performance of H_2/O_2 cycle power plants based on steam-methane reforming is very low - the net efficiency attains only the 26%.