To address these limitations, we demonstrate a novel reactor construction utilizing metal-based walls that is both electromagnetically transparent and capable of sustaining elevated pressures. The key idea of our design is to disrupt the formation of eddy-current loops in the metallic vessel by machining axial slots along its length, allowing the electromagnetic field to penetrate into the interior of the reactor. We define key figures of merit (FoMs) for evaluating a metallized reactor body for efficient induction heating. The “volumetric ratio” describes how much power is dissipated in the susceptor versus the reactor body. The “coupling ratio” measures the apparent load presented to an induction coil with versus without the pressure vessel partially shielding the susceptor. We explore how various geometric parameters of our pressure vessel design impact these key FoMs and the mechanical behavior of our system using multiphysics analysis.
As a proof-of-concept demonstration, we fabricate a 95mm internal diameter reactor vessel from 304 stainless steel and machine a slot to enable electromagnetic field penetration. This slot is then sealed with a non-conductive ceramic based gasket material that is compressed by an additional stainless steel plate. We pressurize the system to 5 bars while performing induction heating of a silicon carbide foam up to a maximum temperature of 550°C. Under these conditions, the system shows leakage of less than 1% per hour, comparable to typical industrial chemical reactors. Additionally, we perform the reverse water gas shift (RWGS) reaction at 5 bars and 550°C and demonstrate performance in line with our multiphysics analysis. While these reaction conditions are fairly mild, they enable induction heating for any number of industrially relevant reactions such as catalytic reforming of naphtha and propane dehydrogenation. We will also present improvements to the mechanical design and construction of the system that should enable operation at reasonable pressures and temperatures up to approximately 25 bars and 800°C.
When designing novel reactor bodies, careful consideration must be given towards adherence to relevant industry standards such as ASME Section VIII, which describes requirements for the construction of pressure vessels. Compliance with these codes is essential for safe operation and is therefore required by many governing bodies for chemical plant installations. Our construction could be made compliant with ASME Section VIII Division 2. Further enhancements to the electromagnetics are described, and the necessary ASME code cases which would need to be accepted are presented.