Modeling of a Single-Tube Steam Methane Reformer: Choice Between Flue Gas Heating and Infrared Burner

Abstract

The article provides a comparative assessment of two design cases of heat input for a compact single-tube steam methane reformer operating at 10 bar and a feed flow rate of 1–3 Nm³/h, filled with a granulated nickel catalyst, and equipped with a 5–15 kW propane–butane burner. In the first design case, the catalyst-filled tube was heated with a flue gas as it was injected from the flame burner (at an excess air ratio of 2.3) through an annular channel that enclosed the tube. In the second design case, the heat was provided by a cylindrical IR burner panel (at an excess air ratio of 1.05) that enclosed the tube. Using mathematical modeling, the performance of both reformer cases was compared, with all other parameters being equal. The IR-burner-based reformer exceeded its flue-gas-heated counterpart in terms of methane conversion, heat recovery efficiency (about twofold for both parameters), the percentage of radiant heat transfer (by a factor of about 2.3), and fuel enthalpy increase (6–7% higher in the second case). When the operating load was tripled, the reformer integrated with the IR burner exhibited a lesser performance drop (regarding all the parameters mentioned above) than the conventionally heated reformer (in particular, the methane conversion declined by 8% in the second design case and by 18% in the first). The parametric calculations based on the permeable burner panel model showed that a Peclet number greater than five (Pe > 5) was able to prevent the panel inlet surface from heating to an extent that could otherwise cause emergency autoignition of the fuel–air mixture at the panel inlet.