Thermal transport model of a sorbent particle undergoing calcination–carbonation cycling

Abstract

A numerical model coupling transient radiative, convective, and conductive heat transfer, mass transfer, and chemical kinetics of heterogeneous solid-gas reactions has been developed for a semitransparent, nonuniform, and nonisothermal particle undergoing cyclic thermochemical transformations. The calcination-carbonation reaction pair for calcium oxide looping is selected as the model cycle because of its suitability for solar-driven carbon dioxide capture. The analyzed system is a single, porous particle undergoing thermochemical cycling in an idealized, reactor-like environment. The model is used to investigate two cases distinguished by the length of the calcination and carbonation periods. The calcination-carbonation process for a single particle is shown to become periodic after three cycles.

Kinetics of Solid-Gas Reactions and Their Application to Carbonate Looping Systems

“…The gas is the continuous phase instead of the solid phase as considered in the pore models. Grain models also consider convection heat transfer in the surface of the particle versus heat conduction in the particles [21] and numerical models have been developed to model conversion and reaction rates [36,37]. The changing grain size (CGS) model considers the system composed by a set of particles as non-porous spherical grains of uniform initial radius which change as the reaction progresses [83].…”

Thermal transport and chemical conversion in single reacting sorbent particles

“…In order to comprehensively model all pertinent transport phenomena and capture both calcination and carbonation reactions, a detailed numerical model of intra‐particle heat and mass transfer coupled to intrinsic chemical kinetics has been developed by Yue and Lipiński, 30‐32 and is used in the study presented here. The numerical model describes heat and mass transfer coupled to chemical kinetics within a single, heterogeneous particle, resolving spatial variation of solid and fluid phase composition, and temperature at different radial locations within the particle.…”

“…Development of such a tool is motivated by the need of aiding the choice of particle size and operating conditions of solar thermochemical reactors. The present study includes (1) characterization of the experimental sorbent material, (2) thermochemical cycling of single large particles of various sizes under various CO 2 atmospheres in a furnace, (3) analysis and discussion of experimental results, (4) reproduction of experimental results via the evaluation of medium characteristics using the previously developed numerical model, 30,31 and (5) comparison of numerical and experimental results during the first thermochemical cycle.…”

Pore and fractal descriptions of a modified CaO‐based sorbent for sequence SO2/CO2 capture behavior

“…Many models, such as the thermal transport model, pore model, grain model, and shrinking core model, have been developed to analyze the kinetic characteristics of CaO‐based adsorbents during the process of carbonation and calcination. The shrinking core model has been known for a long time and has been developed from a macro perspective to describe the kinetics of the hydration of CaO, the cyclic reaction characteristics of CaO with CO 2 , the simultaneous processes of calcination and sintering, and the kinetic characteristics of CaO‐based adsorbent reaction with SO 2 .…”