Computer-aided analysis of critical technologies for hydrogen manufacture

Abstract

The development of new hampered by exhaustive researc several alternative production need for a tool which can prov guide the selection of the mos identify the critical areas of process most efficient. This hydrogen manufacture, consider future of synfuels technology, flowsheet simulation can fill

chemical processes is often h into many variations in methods. There is a real ide early information to help t promising routes and research to make the final study uses the example of ed very important for the to demonstrate how computer this need.

Three different hydrogen production processes were modeled with the ASPEN flowsheet simulation system. Steam reforming and partial oxidation of methane were studied separately and then compared. For each model the process efficiency, defined in terms of product purity, yield, and cost, was analyzed as a function of the operating conditions. Trends in behavior were plotted and methodologies for process optimization found. On comparing the processes, steam reforming was identified as the more cost effective process. Partial oxidation, although resulting in lower initial capital investment for the same size plant, has higher operating costs associated with the need for a pure oxygen feed. This process is competitive with steam reforming only if a very low cost source of oxygen is available.

The third process simulated was electrolysis of water. This demonstrated the method by which flowsheet simulation can be used to compare processes based on very different technologies. It was found that because of the cost of the large amount of electricity needed, electrolysis produces hydrogen at several times the cost as that of the steam reforming process. In addition, the capital expenditure for a large scale electrolysis plant is much higher than the same size steam reforming facility because of the high cost of the necessary electrolysis equipment. This suggests that electrolysis is not a viable alternative for hydrogen manufacture on the scale needed for future synfuels processes.