Modeling of Slurry-Phase Reactors

Sastri et al. (1983) modeled a three-phase noncatalytic but reactive system to produce industrial concentrations of zinc hydrosulfite (ZnS204) in an SBR. Three different approaches were proposed plug-flow, axial diffusion, and perfect mixing mathematical models. The authors compared the numerical solutions for the three models and noticed that the experimental data are well predicted by the axially dispersed plug-flow (diffusion) model, moderately predicted with the plug-flow model, and poorly predicted with the perfect mixing model. 

Vasco de Toledo et al. (2001) developed dynamic models for catalytic slurry reactors. Mass and energy balances, as well as an equation for a coolant fluid were proposed for the hydrogenation of o-cresol on Ni/Si02 to produce 2-methylcyclohexanol. 

Two heterogeneous models were reported. One of them takes into account the external and internal resistance for mass and heat transfer in the catalyst particle (Dynamic model I) and the other one considers only the external resistance to the catalyst (Dynamic model II). 

Numerical simulations allowed the reproduction of the reactor s dynamic behavior, mainly the thermal balance. Despite the differences between the models, both models reproduced almost in the same way in terms of the reactor and coolant fluid temperature dynamic profiles. Regarding the use of a specific model, the authors advise to take into account some points if the internal heat and mass-transfer coefficients of the catalyst particles are significant. Dynamic Model I is more suitable to represent the reactor dynamic behavior in case of difficulties in the measurement of such parameters. Dynamic Model II must be chosen. For design and simulation studies, where computational time and numeric difficulties for model solution are not limiting factors. Dynamic Model I is the most reliable however, if the same factors are limiting. Dynamic Model II should be the best alternative. 

Wama and Salmi (1996) developed dynamic models for three-phase slurry and trickle-bed reactors operating in nonisothermal conditions. The model equations for the gas, liquid, and catalyst phases consisted of parabolic partial differential equations (PDF) and ODEs expressed in terms of volumetric flow rates for concurrent and countercurrent flow. Oxidation of SO2 was chosen for the slurry reactor simulation. 

---