Experimental Study And Modeling Of Biomass Gasification In Fluidized Bed

Biomass is an ideal renewable energy with advantages of abundance resources and neutral in greenhouse gas circulation. The aim of biomass gasification is to obtain combustible gas product, such as CO, H₂, CH₄, etc. In this paper, an experimental study on biomass atmospheric air gasification was performed in fluidized bed. From the pointview of mechanism, experiment and modeling, the gasification of biomass was comprehensive analyzed.Firstly, the investigations of pyrolysis and char gasification of three kinds of biomass (sawdust, peanut shell and rice straw) were preformed using Thermogravimetric analysis. Kinetic parameters were calculated based on TG-DTG curves. The results showed that the model of pyrolysis mechanism was first-order model. The model of char gasification was unreacted shrinking core model. The reactivity of sawdust char was obviously higher than rich straw with CO₂ as gasifying agent.Secondly, atmospheric air gasification of biomass was performed in pilot-scale fluidized bed. The main influencing factors (equivalence ratio, bed temperature, adding steam and adding catalyst) were studied in detail. The results showed that the gas yield was 1.1-1.6m³/kg, the heating value was 4.5-9.5MJ/m³, as the temperature at 850℃with equivalence ratio variant from 0.1 to 0.3. It was observed that the optimal range of ER is at 0.2-0.28. The heating value and gasification efficiency were decreased with equivalence ratio increasing. The CO content and carbon conversion efficiency were increased with temperature. It's favorable for H₂ upgrading with steam addition. The volume content of combustible gas was increased with the addition of dolomite.Thirdly, based on ASPEN PLUS, a biomass gasification model by the method of Gibbs free energy minimization was approached. Using the RYield block and RGibbs block, the model was modified by the restricted equilibrium of the RGIBBS reactor. It was found that the simulation results fit well with the experiment results. The model was proved reliable. Simultaneously, the model was used to simulate the pilot fluidized bed and gasification power plant, it's proved that the model can be applied widely.