Exploration of co-gasification mechanism of sewage sludge and bituminous coal based on reactive force field molecular dynamics simulation

Abstract

The co-gasification of sewage sludge and coal not only facilitates industrial decarbonization but also provides a promising approach for sludge treatment. In this study, the mechanisms of sewage sludge and bituminous coal were explored by the molecular dynamic simulation and the reactive force field. Synergy analysis revealed that the co-gasification process enhanced the production of H₂ and CO by 2.1 % and 1.75 % respectively. The visualization results demonstrate that glyceryl triacetate, leucine, β-D-glucose and coal molecules decompose sequentially to produce fragments during the pyrolysis stage. In the initial gasification stage, a large number of OH radicals participate in the reactions, attacking the fragments into small-molecule highly reactive groups. While H radical is more readily react with the small reactive groups to generate gaseous products. Additionally, molecular cleavage is induced by high temperature and the interaction between OH radicals and molecular fragments is accelerated. More OH and H radicals are generated by using steam, further modulating the H₂/CO ratio. This study offers valuable molecular insights for optimizing the co-gasification process of sludge and coal and decarbonization goals.