A comprehensive model for char particle conversion in environments containing O2 and CO2

Abstract

In this work, conversion of char is studied in a simulation code that includes a simplified heterogeneous adsorption-desorption reaction mechanism for char chemical reactivity and uses GRI-Mech 3.0 as the chemical kinetic mechanism that describes the impact of homogeneous reactions. Besides sub-models for the consequences of chemical reactions, a mode of char particle conversion sub-model is included that describes how particle size and apparent density vary with mass loss as well as a radiation sub-model that describes the radiant exchange of energy between the char particle and surrounding particles and walls. The code is transient and zero dimensional in space, and designed to be used both as a stand-alone gasification/combustion code and as a sub-model for heterogeneous reactions of solid particles in a CFD code.

The effect of turbulence on mass transfer rates between inertial polydisperse particles and fluid

“…An example of the complexity can be seen in the detailed conversion model for single point particle char as described in e.g. Haugen et al (2014Haugen et al ( , 2015. In order to make the results obtained in the following as general as possible, and to be able to isolate the effects of the turbulence alone, we will here use a simplified description of the chemical reactions.…”

Numerical Study of Hydrogen Inhibition of Char Gasification Using Detailed Hetero- and Homogeneous Chemical Kinetics

“…For more information on the model, the reader is referred to Haugen, Mitchell and Tilghman (2015) . 15 In the following, particles are assumed to be spherical and uniform in composition and morphology, while the ash is uniformly distributed throughout the particle volume.…”

“…For a full description of all relevant equations, the reader is referred to Haugen et al 15 The gas phase is defined by three governing equations describing the evolution of mass, species and temperature in the gas phase. The first equation describes the evolution of the mass of the gas phase m g ;…”

“…15 In the following, particles are assumed to be spherical and uniform in composition and morphology, while the ash is uniformly distributed throughout the particle volume. In addition, ash in the char can not react or be evaporated, and there is no exchange of mineral matter between the particle and the gas phase.…”

“…The molar rate of adsorbed species production is given by R spec, j while A is an active surface area 15 Species concentrations at the particle surface…”