Numerical Investigation of Catalytic Tube Wall Failure
A hydrogen reformer furnace is used to convert natural gas into hydrogen through a series of catalytic reactions. The combustion process in the furnace provides the heat to maintain the chemical reaction inside the catalyst tubes.
Temperature control of the catalyst tubes is a fundamental design requirement of the hydrogen reformer furnace, as the temperature should be maintained in the range which could maximize catalyst reactivity while minimizing any damage to the catalyst pipes. However, there is clearly non-uniform heat distribution determined using IR thermography and also confirmed via inspection of the tubes during turnarounds. This has caused shortened tube life for the catalyst tubes in the hotter zones of the furnace.
In order to identify the cause of the non-uniform heat distribution problem therefore improve the furnace performance, Computational Fluid Dynamics (CFD) had been employed to model a hydrogen reformer furnace at a local plant. The flow characteristics in the furnace had been investigated. The temperature distribution on the catalyst tubes had been analyzed to assist in the definition of the overheating problem. The parametric study had also been conducted to provide insight into the optimization of heating process.
By analyzing the simulation results, the flame from the inner rows of burners impinges on the catalyst tubes, causing higher temperature condition near the tube tops. Hot spots had been identified at the bottom of the tubes by the exit. The tunnels located at the bottom have great impact on the temperature distribution on the catalyst tubes due to the changes in the hot flue gas flow pattern. The overheating problem could be partially solved by adjusting the opening areas at the bottom tunnels.
Click the movie below to see the Hydrogen Reformer in detail.
Faculty Collaborator: Dr. Chenn Q. Zhou