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Dynamic modeling and simulation of a flash clay calciner

Nicola Cantisani, Jan Lorenz Svensen, Ole Fink Hansen, John Bagterp Jørgensen

TL;DR

The paper delivers a dynamic, first-principles model of a flash clay calciner formulated as a system of PDAEs that couple kaolinite calcination kinetics $r = k c_{AB_2}^3$ with $k = k_0\exp(-E_A/(R T_s))$ and detailed thermodynamics, transport, and energy exchanges between solid and gas phases. Through spatial discretization, the PDAEs are transformed into a DAEs framework suitable for efficient simulation, enabling dynamic prediction under changing inputs and serving as a foundation for model-based control in green cement production. Key contributions include a modular block structure, rigorous thermodynamic constraints, and a finite-volume discretization yielding a scalable $10 N_z$-equation ODE/DAE system solvable with standard solvers. Simulation results demonstrate rapid transients and well-defined steady-state profiles, supporting design, optimization, and control development for electrified, CO$_2$-reduced calcination processes.

Abstract

We present a novel dynamic model of a flash clay calciner. The model consists of thermophysical properties, reaction kinetics and stoichiometry, transport, mass and energy balances, and algebraic constraints. This gives rise to a system of partial differential-algebraic equations (PDAE). Spatial discretization is performed to convert the PDAEs into a system of differential-algebraic equations (DAE). The model can be used, for example, to perform dynamic simulations with changing inputs, and process design and optimization. Moreover, it can be used to develop model-based control, which is relevant for flexible operation of a clay calcination plant for green cement production.

Dynamic modeling and simulation of a flash clay calciner

TL;DR

The paper delivers a dynamic, first-principles model of a flash clay calciner formulated as a system of PDAEs that couple kaolinite calcination kinetics with and detailed thermodynamics, transport, and energy exchanges between solid and gas phases. Through spatial discretization, the PDAEs are transformed into a DAEs framework suitable for efficient simulation, enabling dynamic prediction under changing inputs and serving as a foundation for model-based control in green cement production. Key contributions include a modular block structure, rigorous thermodynamic constraints, and a finite-volume discretization yielding a scalable -equation ODE/DAE system solvable with standard solvers. Simulation results demonstrate rapid transients and well-defined steady-state profiles, supporting design, optimization, and control development for electrified, CO-reduced calcination processes.

Abstract

We present a novel dynamic model of a flash clay calciner. The model consists of thermophysical properties, reaction kinetics and stoichiometry, transport, mass and energy balances, and algebraic constraints. This gives rise to a system of partial differential-algebraic equations (PDAE). Spatial discretization is performed to convert the PDAEs into a system of differential-algebraic equations (DAE). The model can be used, for example, to perform dynamic simulations with changing inputs, and process design and optimization. Moreover, it can be used to develop model-based control, which is relevant for flexible operation of a clay calcination plant for green cement production.
Paper Structure (18 sections, 49 equations, 4 figures, 2 tables)

This paper contains 18 sections, 49 equations, 4 figures, 2 tables.

Table of Contents

  1. Introduction
  2. Process description
  3. Flash clay calciner model
  4. Stoichiometry and kinetics
  5. Thermodynamic functions
  6. Solid phase
  7. Gas phase
  8. Transport model
  9. Velocity
  10. Viscosity
  11. Advection and diffusion
  12. Mass balance
  13. Energy balance
  14. Algebraic relations
  15. Summary
  16. ...and 3 more sections

Figures (4)

  • Figure 1: Clay pyro-activation loop. The process consists of a pre-heating zone with 2 cyclones, a calciner, an electric hot gas generator, a separation cyclone, and a gas recirculation loop. The right part shows a zoom of the calciner.
  • Figure 2: Finite volume discretization of the calciner.
  • Figure 3: States in time and space: concentrations, temperature of the solid and the gas, pressure.
  • Figure 4: Steady state: reaction kinetics and gas-solid temperature profile along the calciner.