System Design Study of a Membrane Reforming Hydrogen Production Plant Using a Small Sized Sodium Cooled Reactor

In phase II of a feasibility study on commercialized fast reactor cycle system of Japan Nuclear Cycle Development Institute, we are finding a concept of a multi-purpose small sized fast reactor with various requirements, such as, safety and improved economical competitiveness. In this study, a membrane reforming hydrogen production plant using a small sized sodium cooled reactor was designed as one of promising concepts. In the membrane reformer, methane and steam are reformed into carbon dioxide and hydrogen with sodium heat at a temperature 500deg-C. In the equilibrium condition, steam reforming proceeds with catalyst at a temperature more than 800deg-C. Using membrane reformers, the steam reforming temperature can be decreased from 800 to 500deg-C because the hydrogen separation membrane remove hydrogen selectively from catalyst area and the partial pressure of hydrogen is kept much lower than equilibrium condition. In this study, a hydrogen and electric co-production plant has been designed. The reactor thermal output is 375MW and 25% of the thermal output is used for hydrogen production (70000Nm³/h). The hydrogen production cost is estimated but it is still higher than the economical goal. The major reason of the high cost comes from the large size of hydrogen separation reformers because of the limit of hydrogen separation efficiency of palladium membrane. A new highly efficient hydrogen separation membrane is needed to reduce the cost of hydrogen production using membrane reformers. There is possibility of multi-tube failure in the membrane reformers. In future study, a design of measures against tube failure and elemental experiments of reaction between sodium and reforming gas will be needed.