A point model for the design of a sulfur trioxide decomposer for the SI cycle and comparison with a CFD model

Operating under the harsh environment with the significant energy consumption, the sulfur trioxide decomposer is one of the most important components, yet challenging tasks for the designers of an efficient SI cycle. We developed a point model to provide important guidelines for designers of a sulfur trioxide decomposer through estimating outlet physical quantities, such as outlet decomposition ratio, outlet temperature, and pressure drop of a sulfur trioxide decomposer. Then, results of the point model were compared to independent predictions obtained using a CFD model over a wide range of conditions with good agreement. The model indicates that decomposition ratio is a function of the representative non-dimensional design parameter and inlet flow composition. As inlet flow composition rarely affects outlet decomposition ratio, we found out that outlet decomposition ratio can be approximated solely as a function of the non-dimensional design parameter. We demonstrated that the model can provide general guidelines for designers of a sulfur trioxide decomposer to achieve a target decomposition ratio with an economical design. It turns out that an increase in operating pressure and catalyst surface area leads to an increase in outlet decomposition ratio while the reverse is true for an increase in mass flow rate.