Experimental tests on steam reforming of natural gas in a reformer and membrane modules (RMM) plant

A reformer and membrane modules (RMM) test plant with a hydrogen capacity of 20 Nm3/h has been designed and built to investigate the performance of said innovative architecture at an industrial level. A major benefit of the proposed RMM configuration is the shift in the chemical equilibrium of the steam reforming reactions by removing the hydrogen produced at high temperatures, thanks to the integration of highly selective Pd-based membranes. In this way, the process can operate at a lower thermal level (below 650 °C in comparison to the 850–950 °C temperature needed in traditional plants). Four types of Pd-based membranes, three already installed and one yet to be assembled, with an active area in the range 0.12–0.4 m2, are tested in order to compare performance in terms of permeated hydrogen flux. Moreover, a noble metal catalyst supported on a SiC foam catalyst is placed inside the reactor in order to improve thermal transport inside the reforming tubes. Firstly, this paper introduces the plant design criteria: the process scheme, the construction engineering of reformers and membrane units and the control system implemented to maximize experimental outputs. The main experimental tests results are then reported and discussed, at least in a preliminary manner. About 1000 operating hours and more than 70 heating and cooling cycles were performed. The average H2 permeability for membranes tested are calculated and compared, and permeability expressions are reported. An overall feed conversion of 57.3% was achieved at 600 °C, about 26% higher than what can be achieved in a conventional reformer at the same temperature, thanks to the integration of selective membranes. The 20 Nm3/h RMM installation makes it possible to completely understand the potential of selective membrane application in industrial high-temperature chemical processes, and represents a unique installation worldwide.