Étude numérique de la production de gaz de synthèse par combustion riche du méthane dans un brûleur poreux

Abstract

Syngas is a valuable product used in the chemical industry to produce biofuels or methanol. The combustion of an air-fuel mixture at a high equivalence ratio in a porous medium enables the production of syngas. The objective of the present research is to numerically model the production of syngas in a porous burner, based on a diamond lattice structure, through the rich combustion of methane. The geometry of the porous matrix is derived from the one proposed by Samoilenko et al., 2019 to obtain regular porous matrices with a diamond lattice structure (obtainable by 3D printing) having similar properties (in terms of permeability and porosity) than industrial foam. The different parameters studied are the porosity and pore density. The novelty is the introduction of a burner having a graded geometry. Direct 3D simulation at the pore scale is used because of the geometrical complexity of the porous matrix. The combustion of an air-methane mixture with an equivalence ratio of 2 is modelled considering laminar flows. The flow rate is adjusted to stabilize the flame and study the nature of the so-produced syngas. The numerical model and the resolution are performed using the Star-CCM+ CFD software. The produced syngas exhibits a H2/CO ratio close to 1 in all the studied cases but the quantities of the syngas produced are different. The conversion efficiency varies from 41% for the reference case to 43% when the pore density increases. It rises up to 59% when the porosity decreases (divided by 2) and it even reaches 63% for the graded geometry. The study of soot precursors also shows a 10% decrease in the latter case. In any cases, the increase in the preheating efficiency results in an increase in the production of syngas. Also, the reaction takes place in one cell of the structure in all cases. The conversion to syngas is thus promoted by the recirculation of heat in the solid material (here SiSiC). To that end, the following parameters can be influenced: increasing the pore density or decreasing the porosity to maximize the exchange surface or having a variable geometry with dense pores in the preheating zone and more space in the reaction zone. The variable geometry represents an alternative to improve the conversion yields without requiring the use of catalyst materials. It can, moreover, be easily obtained by 3D printing.

Date	21 Sept 2022
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Patrice Seers (Supervisor) & Romain Lemaire (Co-supervisor)