Study On The Process And Influence Factors Of Coal And Biomass Co-gasification

In this paper,a new type of gasifier was built,and the oxygen enriched reaction performance of biomass gasification with biomass-coal co-gasification in the reactor were studied numerically on the basis of experiments.The 3D numerical model was established by FLUENT and the Eulerian-Lagrangian method was selected to describe the three phases flow.The gas was treated as continuous phase and the fuel particles were treated as discrete phases,respectively.The optimal reaction mechanism was obtained by optimization,and used for further numerical simulation.Simulation results show the flow characteristics,where the lower-stage of the reactor performs the characteristics of distributed entrained flow,and the upper-stage shows fluidized bed characteristics by fluid upward returning.In addition,the influencing factors of oxygen-carbon mass ratio(O/C)and oxygen concentration of oxygen enriched air,were studied based on the experiment.The results show that as the O/C increases,the content of H2 and CO2 in the syngas gradually decreases but the content of CO remains stable.The effect of O2 concentration on syngas composition is related to its O/C.The concentrations of CO and CO2 rise as the O2 concentration increases.However,for the O/C of 0.35?0.65,as the oxygen concentration increases,the H2 concentration shows a trend of firstly increase and then decrease.Finally,the co-gasification process of coal and biomass particles in the reactor was studied based on the simulation results of biomass gasification,the three-phase flow state in the reactor was analyzed,and the separation characteristics of coal and biomass was discovered.It is found that with the increase of the biomass blending ratio,the low heating value(LHV)of the syngas gradually decreases,and the cold gas efficiency shows a trend of first increasing and then decreasing.The maximum cold gas efficiency was reached when the biomass blending ratio was 67/33.With the increase of oxygen-enriched concentration,the LHV of syngas and its cold gas efficiency also increase.All the numerical and experimental results are in good agreement.