Engineering Scale up of Renewable Hydrogen Production by Catalytic Steam Reforming of Peanut Shells Pyrolysis Products

Renewable hydrogen may be produced in the near term at a cost that is competitive with natural gas reforming by integrating hydrogen production with existing industrial utilization of agricultural residues. A team of government, industrial, and academic organizations is developing a steam reforming process to be demonstrated on the gaseous byproducts from a process for making activated carbon from densified peanut shells [1]. The thermochemical user’s facility (TCUF) at NREL was the site for the initial shakedown of the scaled up reactor. It was interfaced with a 20-kg/hour fluidized-bed fast pyrolysis system to take advantage of process chemical analysis and computer control and monitoring capabilities. This paper reports the results from the shake down phase of this engineering demonstration project. After an initial problem with the heaters that required modification to the heater control strategy, the system passed mechanical shakedown tests and was integrated with the TCUF fluid bed pyrolysis system. The new control system developed to protect the reactor is based on 30 heater-monitoring thermocouples to prevent overheating in the case of heater malfunction. The 30-cm, catalytic, steam-reforming reactor was then successfully operated on methane and peanut shell pyrolysis products. Experiments with peanut pyrolysis vapor reforming duplicated the results in a 5-cm bench scale unit with the aqueous fraction of wood pyrolysis oil. This is the first time that the whole pyrolysis vapors have been processed in the fluid bed reforming process. Although peanut shells have a unique composition, containing high levels of lignin and protein, no problems were encountered in the reforming of the vapors. The only other significant problem uncounted was the plugging of the reformer distribution plate by fine char that acted as a nucleus for vapor deposition, slowly plugging the reactor. A hot gas filter was installed to remove the char and the reactor was operated for 30 hours without plugging The reformer has been shipped to the industrial site in Georgia where the shake down will continue with a 100 hours of run time. 1 Proceedings of the 2002 U.S. DOE Hydrogen Program Review NREL/CP-610-32405