Pressure drop and heat transfer of ZoneFlowTM structured catalytic reactors and reference pellets for Steam Methane Reforming

Structured catalytic reactors have the potential to combine reduced pressure drop and improved heat transfer compared to conventional pellets. In the present study, the pressure drop and heat transfer coefficient between the tube wall and the process gas were measured experimentally for annular structured ZoneFlow reactors of different design and for two commercial reference pellets. The ZoneFlow reactors differ by the design of the central rod that supports the near-wall annular casing. The experiments were carried out in a 1 m long reactor, at atmospheric pressure and with air flow rates from 70 to 330 Nm/h. To measure the heat transfer coefficient, the furnace was set at a constant temperature that was varied in the range 100–500 °C and the axial profiles of the tube wall and gas temperatures were measured. Using the experimental data, correlations for the friction factor and the Nusselt number were derived and the introduced parameters estimated using non-linear regression. A correlation for the static contribution to heat transfer for the structured reactors was derived from 3D numerical simulations. The correlations were then used to evaluate the pressure drop–heat transfer advantage of the structured reactors compared to the reference pellets at typical industrial steam methane reforming conditions. The data show that ZoneFlow reactors can provide a roughly doubled heat transfer coefficient at comparable pressure drop than the tested reference pellets. Furthermore, modification of the central rod support structure was found an efficient way to balance the pressure drop–heat transfer advantage of ZoneFlow reactors using an identical design casing