Anti-carbon Deposition Of CuFeAlO₄ In Coal Direct Chemicallooping Combustion On Hypoxic Dilution

Chemical Looping Combustion technology（CLC）is a technology that can efficiently capture carbon dioxide and achieve carbon reduction to support the"dual carbon"goal.Carbon deposition occurs in CLC of coal,which hinders the performance of oxygen carrier to transfer oxygen and heat,and reduces the combustion efficiency and carbon capture efficiency of the whole system.In order to control aromatic carbon deposition which is difficult to remove,CuFeAlO₄oxygen carrier was used in direct chemical chain combustion of coal in this paper.The influence of aromatic carbon generation of CuFeAlO₄oxygen carrier under different working conditions was studied,the performance of oxygen carrier was characterized,and the relationship between the formation reason of aromatic carbon deposition and combustion reaction conditions was explored.To search for feasible carbon deposition inhibition conditions and methods.The main results are as follows:（1）CuFeAlO₄oxygen carriers were prepared by two methods,and characterized and analyzed by XRD,SEM and FT-IR.The results show that both oxygen carriers have good spinel structure,good particle dispersion,abundant pore structure and strong thermal stability.After reduction reaction of CuFeAlO₄oxygen carrier prepared by sol-gel method,it can be seen that there is a small amount of carbon attached and obvious agglomeration phenomenon.（2）In the aspect of aromatic carbon deposition,it is analyzed that the carbon content,hydrogen carbon ratio and volatile matter of coal have great influence on the generation of aromatic hydrocarbons.（3）The effect of combustion ratio on the generation of aromatic hydrocarbons is as follows:with the increase of combustion ratio,the absolute amount of aromatic hydrocarbons decreases correspondingly.When the combustion ratio is 5:1,the absolute amount of aromatic hydrocarbons generated is the largest.When the combustion ratio is 20:1,the absolute amount of aromatic hydrocarbons generated is the smallest,and there is no significant difference between 25:1 and 20:1.（4）The effect of CO₂with different concentrations on the generation of aromatic hydrocarbons in different coals is as follows:at 60%CO₂concentration,the aromatic hydrocarbon generation of bituminous coal continues to decrease to the lowest value.The content of aromatic hydrocarbons produced by anthracite decreased firstly and then fluctuated slightly.The content of aromatic hydrocarbons produced by anthracite reached the lowest value at 40%CO₂concentration.According to the production amount of saturated hydrocarbon and aromatic hydrocarbon,the inhibition effect of aromatic carbon deposition produced by bituminous coal is the best under 60%CO₂concentration.The inhibition effect of aromatic carbon deposition produced by anthracite was the best at 40%CO₂concentration.（5）Under different CO₂concentrations,the effect of CuFeAlO₄oxygen carriers prepared by the two methods on aromatic carbon deposition is as follows:At 60%CO₂concentration,the inhibition effect of sol-gel CuFeAlO₄oxygen carriers on aromatic carbon deposition is the best.At 100%CO₂concentration,the inhibition effect of mechanical CuFeAlO₄oxygen carrier aromatic carbon deposition is the best.The results show that the carbon content,molar hydrogen carbon ratio and volatile matter in coal structure have different effects on the formation of aromatic carbon deposition.The increase of combustion ratio can reduce the formation of aromatic carbon deposition.Under the condition of low oxygen dilution（CO₂atmosphere）,the amount of aromatic hydrocarbons produced by bituminous coal and anthracite can be inhibited.In CO₂atmosphere,the amount of aromatic hydrocarbons produced by CuFeAlO₄oxygen carriers is less than that produced by CuFeAlO₄oxygen carriers without hypoxic dilution.Meanwhile,sol-gel CuFeAlO₄oxygen carriers have better carbon deposition resistance than mechanical oxygen carriers.