Thermal Assessment of a Micro Fibrous Fischer Tropsch Fixed Bed Reactor Using Computational Fluid Dynamics

Abstract

A two-dimensional (2D) Computational Fluid Dynamics (CFD) scale-up model of the Fischer Tropsch reactor was developed to thermally compare the Microfibrous-Entrapped-Cobalt-Catalyst (MFECC) and the conventional Packed Bed Reactor (PBR). The model implements an advanced predictive detailed kinetic model to study the effect of a thermal runaway on C5+ hydrocarbon product selectivity. Results demonstrate the superior capability of the MFECC bed in mitigating hotspot formation due to its ultra-high thermal conductivity. Furthermore, a process intensification study for radial scale-up of the reactor bed from 15 mm internal diameter (ID) to 102 mm ID demonstrated that large tube diameters in PBR lead to temperature runaway >200 K corresponding to >90% CO conversion at 100% methane selectivity, which is highly undesirable. While the MFECC bed hotspot temperature corresponded to <10 K at >30% CO conversion, attributing to significantly high thermal conductivity of the MFECC bed. Moreover, a noticeable improvement in C5+ hydrocarbon selectivity >70% was observed in the MFECC bed in contrast to a significantly low number for the PBR (<5%).

Proxy quality control of biomass particles using thermogravimetric analysis and Gaussian process regression models

“…Existing equations and models quantifying radial temperature distribution and the radial heat transfer problem of reactors are available as frameworks to reconcile with the predicted preparation temperature distribution. [59][60][61] Information about the radial spatial distribution of the biomass particles within the reactor would likely be necessary for this purpose. The resulting radial temperature gradient would correspond to the point at which the axial temperature gradient is greatest.…”

“…The next steps for this project could include using the predicted maximum experienced temperature distribution data as a basis for more rigorously quantifying the radial temperature distribution within the reactor used for the preparation of the biomass particles. Existing equations and models quantifying radial temperature distribution and the radial heat transfer problem of reactors are available as frameworks to reconcile with the predicted preparation temperature distribution 59–61 . Information about the radial spatial distribution of the biomass particles within the reactor would likely be necessary for this purpose.…”

An Overview of Low-Temperature Fischer–Tropsch Synthesis: Market Conditions, Raw Materials, Reactors, Scale-Up, Process Intensification, Mechanisms, and Outlook

“…With the development of computational tools, the study of mass, energy, and momentum transfer in these latest models through Computational Fluid Dynamics (CFD) is essential because it analyzes the system within a wide range of operating values and reduces costs by not having to manufacture new physical designs/prototypes for analysis. All of these phenomena have current relevance in process intensification and scaling − and can be analyzed through digital prototypes reducing time and cost. Through CFD, it is possible to simulate different turbulence modelsi.e., Direct Numerical Simulation (DNS), Large Eddy Simulation (LES), Reynolds-Averaged Navier–Stokes (RANS), Detached Eddy Simulation (DES)interfacial forcesi.e., drag, turbulent dispersion, and liftand multiphase flowsusing the Eulerian, Mixture, and Volume of Fluid Method (VOF) models.…”

Thermal Stability for the Continuous Production of γ-Valerolactone from the Hydrogenation of N-Butyl Levulinate in a CSTR

“…One way to decrease the thermal risk is to work in continuous mode in a steady-state regime [37]. Nevertheless, one needs to assess the thermal stability of such continuous reactor [38,39]. In the literature we can find studies about thermal stability, dynamic stability, and sensitivity assessments in continuous reactors for reactions such as the hydrolysis of acetic anhydride, polystyrene production in CSTRs, and light-cycle oil hydrotreatment [40][41][42][43].…”