CPFD Simulation of Enhanced Cement Raw Meal Fluidization Through Mixing with Coarse, Inert Particles

EasyChair Preprint 4624

Abstract

Computational particle fluid dynamics (CPFD) simulations are used to study an electrically heated bubbling fluidized bed (BFB) used as a calciner in a cement manufacturing process, applying a binary-particle fluidization system. Owing to the fine particle size (0.2–180µm) of the limestone in the cement kiln process, a conventional BFB may be difficult to apply due to particle cohesion causing poor flowability of particles. To enhance the fluidization of raw meal particles, mixing them with inert Geldart B particles was proposed. The inert particles may provide a homogeneous distribution of the limestone particles and help to fluidize them. After the raw meal particles have been calcined, they must be separated from the inert particles. This can be done by increasing the velocity of the CO2 used for fluidization to a value sufficiently high to entrain the raw meal particles, but still sufficiently low that the inert particles are not entrained. This means that the fluidized bed calciner process is designed as a semi-batch process operating in two modes: the calcination mode (with a low gas velocity) and the entrainment mode (with a higher velocity). The CPFD software Barracuda was used for simulations to study suitable operational conditions at 1173K, such as the particle size distribution of the inert particles and the fluidization gas velocity. Inert particles with a diameter in the range 550–800µm, an average minimum fluidization velocity of 0.129m/s and a terminal settling velocity of 3.24m/s appeared as suitable for the calciner operation. The impact of gas velocity variation on the fluidization of the particle mixture was studied, and a suitable range of velocities for the calcination and entrainment modes could be determined. The simulations revealed that mixing raw meal particles with inert coarse particles could enhance the flowability in the FB reactor, indicating it is possible to apply the concept in a full-scale calcination process

Keyphrases: Barracuda, CPFD, Limestone, calciner, electrification, fluidized bed

@booklet{EasyChair:4624,
  author    = {Nastaran Ahmadpour Samani and Chameera K. Jayarathna and Lars-Andre Tokheim},
  title     = {CPFD Simulation of Enhanced Cement Raw Meal Fluidization Through Mixing with Coarse, Inert Particles},
  howpublished = {EasyChair Preprint 4624},
  year      = {EasyChair, 2020}}