Recent progress in CFD modeling of powder flow charging during pneumatic conveying

TL;DR

This paper reviews recent advances in CFD modeling of powder flow charging during pneumatic conveying, highlighting new models, their limitations, and future research directions to improve predictive capabilities.

Contribution

It introduces advanced models like the non-uniform charge model and discusses the transition from Eulerian-Lagrangian to Eulerian methods for better simulation efficiency.

Findings

Condenser models fail to predict key features of powder electrification.

New experiments led to the development of the non-uniform charge model.

Eulerian methods now successfully describe powder charging, enabling full-scale simulations.

Abstract

Thus far, Computational Fluid Dynamics (CFD) simulations fail to predict the electrostatic charging of particle-gas flows reliably. The lack of a predictive tool leads to powder operations prone to deposits and discharges, making chemical plants unsustainable and prime candidates for explosions. This paper reviews the rapid progress of numerical models in recent years, their limitations, and outlines future research. In particular, the discussion includes CFD models for the physics and chemistry of particle electrification. The condenser model is most popular today in CFD simulations of powder flow electrification but fails to predict most of its features. New experiments led to advanced models, such as the non-uniform charge model, which resolves the local charge distribution on non-conductive particle surfaces. Further, models relying on the surface state theory predicted bipolar charging of polydisperse particles made of the same material. While these models were usually implemented in CFD tools using an Eulerian-Lagrangian strategy, recently Eulerian methods successfully described powder charging. The Eulerian framework is computationally efficient when handling complete powders; thus, Eulerian methods can pave the way from academic studies to application, simulating full-scale powder processing units. Overall, even though CFD models for powder flow charging improved, major hurdles toward a predictive tool remain.