Barracuda Virtual Reactor technology is designed from the ground up to address issues unique to fluidized beds and other fluid-particle systems. It augments traditional R&D and engineering practices, and complements other computational tools such as Computational Fluid Dynamics (CFD), Discrete Element Modeling (DEM) and process simulation.
Do you not currently simulate your fluid-particles systems? Then you have a lot in common with most of our customers. Before Barracuda Virtual Reactor, only the largest R&D groups had initiatives aimed at customizing CFD or other tools to gain insights into specific aspects of fluid-particle flows.
Today, Barracuda Virtual Reactor is used to augment traditional R&D, technology commercialization, industrial scale-up and trouble-shooting activities across multiple application areas including FCCU/refining, petrochemicals, advanced recycling / chemical recycling of plastics, waste-to-energy processes, gasification, pyrolysis, cement calcination, polysilicon manufacture, titanium dioxide production, materials processing, chemicals, power generation, clean technologies, renewables, general/applied fluidization research and more. The Virtual Reactor technology can be utilized via software licensing or a variety of services and technology transfer options that are customizable to meet your needs.
Do you already utilize simulation technology? If so, Virtual Reactor will be a great addition to your toolkit. Many of our customers also use process simulation, CFD, and/or DEM for situations best-suited for those tools, and Virtual Reactor for fluid-particle flow applications.
Process Simulation is a powerful tool used to simulate flows through a complex system such as a chemical plant. The performance of individual unit operations (e.g. a fluidized bed reactor) is described via a model of the unit as a whole. Well-tuned process simulation models are typically well suited for interpolation and limited extrapolation from the conditions under which the model was developed.
Barracuda Virtual Reactor provides complementary information to the outputs of process simulation models. Process simulation tells you how an existing unit or process will respond to incremental changes in operating conditions. The Barracuda technology addresses what can be expected if you make changes to the unit or process itself. Virtual reactor is suitable to answer questions about changes to unit geometry, internals, inlets and/or outlets, particle properties, flow rates, operating conditions, etc.
CFD, or computational fluid dynamics, is a proven technology for the simulation of fluid flows. Fluidized beds, and other fluid-particle systems, often exhibit characteristics typical of fluid flow, so CFD is necessary for simulations of these systems… necessary, but not generally sufficient. Barracuda Virtual Reactor was designed to complement CFD for systems where both the fluid and particle phases are important.
Fluidized beds generally contain trillions of discrete particles (or more!), so the biggest challenge for adapting general-purpose CFD for fluid-particle flows relates to the numeric approach for including the particulate phase. A few of the more common approaches include:
- Two-Fluid Models
Two Fluid Model (TFM) is a common term used to describe Eulerian multiphase approaches aimed at resolving both the fluid and particulate phases on the grid/mesh used by the CFD models. The conservation equations (mass, momentum, energy) for both the fluid and particle phases are spatially discretized on the underlying Eulerian grid, with closure models (typically drag and granular temperature) used to couple the phases to each other. However, there are a few very significant challenges inherent in this approach. Namely:
- Each Eulerian phase captures average particle properties only. Thus, the approach is akin to modeling mono-size particles and other uniform properties in the cell (one temperature, composition, etc.).
- Additional size bins can be added by added additional Eulerian phases. But each phase also adds considerable computational cost. At most a few discrete sizes are typically captured with the method.
- Mapping to the Eulerian framework assumes a continuum, which can pose challenges for discrete particles.
- It’s generally recommended that the cell size be limited to a small multiple of the particle size (e.g. 10x), which often limits the practical 3D modeling of industrial-scale systems.
- Discrete Phase
Discrete Phase Model (DPM) is a common term used to describe Eulerian-Lagrangian multiphase approaches. The continuum fluid equations are solved on the underlying Eulerian grid while the particles remain discrete. Unfortunately, most DPM models are limited to cases where the particle field is very dilute. Often it is assumed that the fluid drags the particles, but the particles have no (or limited) influence on the fluid phase. Thus many DPM models are not applicable to fluidized beds.
- Lattice Boltzmann Method
The Lattice Boltzmann Method (LBM) is an attractive numerical approach because the motions of discrete particles are fully resolved. The fluid flow profiles around each particle result in pressure imbalances which move the particles without the need for drag closure models. Unfortunately, the high resolution of the LBM generally limits its use to small subsets of systems with very few particles, 2D approximations, or both. For this reason, LBM is not typically applicable for industrial-scale fluid-particle systems.
General-purpose CFD is an amazing technology, but attempts to use it for industrial fluid-particle systems are often found lacking. For this reason, the Barracuda technology was designed from the ground up to complement your in-house CFD capabilities by addressing issues unique to fluidized beds and other fluid-particle systems.
Frederik Zafiryadis, Aerotak, compares Barracuda Virtual Reactor with DEM
The discrete element method, or DEM, is a standard technology addressing engineering problems related to granular flows. DEM focuses on the motion, collisions and contacts between discrete particles, and is generally applicable for situations where the engineering outcome is primarily dependent upon individual particle collisions.
For fluid-particle flows, however, both the fluid and particulate fields contribute to the overall system dynamics. It is possible to couple DEM with CFD for applications with small physical scales or limited numbers of particles but the computational expense (from large particle counts and small time steps required to resolve collisions) generally makes CFD/DEM coupled approaches impractical for industrial applications involving fluidization.
Barracuda Virtual Reactor complements DEM for systems involving fluidized beds and other applications where both the fluid and particle fields are important. Virtual reactor retains the discrete, Lagrangian formulation of the particulate phase, but is natively formulated to extend to industrial-scale systems with trillions of particles (or more!), plus computes fluid flow, heat balance and chemical reactions in an efficient solution scheme.
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