Modified Discrete Random Pore Model Considering Pore Structure Evolution to Depict Coal Chars Combustion in O₂/CO₂

Abstract

The O 2 /CO 2 combustion of coal chars currently considered as one of the promising technologies has a remarkable effect on reducing greenhouse gas emissions, and it is of importance to investigate the mathematical model of pore evolution at char reaction process, while discrete random pore model (DRPM) can be usually considered as the mathematic modeling of pore evolution for effective prediction of char combustion at O 2 /CO 2 . In this work, pore structure variation of three chars during reaction at O 2 /CO 2 were presented by the N 2 isothermal adsorption/desorption method. The universally used assumption of proportional relation of superficial area and combustion rate was improved for application to coal chars, indicating true superficial area associated with the reaction rate should be corresponding to the pore superficial area 2πl(r 0 + θΔr/2). Therefore, a new pore structure model (MDRPM) was created to simulate carbon conversion of three coals combustion process in O 2 /CO 2 when chemical reaction is considered. Compared with the Liu model, the Struis model, as well as the Bhatia model (DRPM), carbon conversion calculated by the MDRPM was more consistent to experimental values for three char reaction process. According to these models, the combustion characteristic of coal chars in O 2 /CO 2 was investigated.

Reaction–Diffusion Model for Gasification of a Shrinking Single Carbon-Anode Particle

“…It simplifies the equations and lets us find the analytical solution with reasonable results. The influencing factors, such as pore characteristics and the superficial area of porous particles during gasification are taken into account. ,, t in MRPM represents the gasification time, and ψ and, ω are the structural parameter and the power-law constant, respectively. ω is the power-law constant that can be positive or negative that shows the effects of time on ks that is defined by [1 + (ω + 1)­(α t )].…”

First principle based rate equation (1pRE) for random pore model in Fe2O3 reduction reaction with CO

“…Bhatia and Vartak 17 introduced a discrete random pore model (DRPM) that considered the discrete nature of the solid phase in microporous materials, leading to necessary adjustments to the commonly held assumption of a direct proportionality between reaction rate and pore surface area. In a related development, Fei et al 18 extended this concept by creating a modified discrete random pore model (MDRPM) designed to simulate the conversion of carbonaceous materials, such as chars, during combustion in an O 2 /CO 2 environment. The model took into account the true superficial area associated with the reaction rate, which corresponded to the pore superficial area 2 πl ( r 0 + θ Δ r /2).…”