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Keywords:

  • mass transfer;
  • mathematical modeling;
  • heat transfer;
  • reaction kinetics;
  • circulating fluidized beds

Abstract

The heat and mass-transfer phenomena occurring during the calcination of limestone particles was studied by means of modeling. The applicability of two modeling methods for calcination was compared under different conditions. An unsteady numerical particle model with mass, momentum, energy balance, and shrinking core models were chosen for the study. The influence of different phenomena (chemical kinetics, advective and diffusive mass transfer, and heat transfer) in different conditions was evaluated with the aid of dimensionless parameters, and their relative importance was shown in a regime chart. Especially, the significance of advection was studied and its importance in high CO2 concentration was observed. Local temperatures inside the particle were obtained by solving a dynamic energy balance in each particle layer including calcination reaction energy and conduction heat transfer. Noticeable temperature differences between constant ambient conditions and the particle were observed. © 2011 American Institute of Chemical Engineers AIChE J, 58: 2563–2572, 2012