Study On Pyrolysis Characteristics And Simulation Of Three Components Of Biomass Driven By Concentrated Solar Energy

Biomass,the only clean energy that is carbon neutral throughout its life cycle,has low sulfur and ash content to be used as an ideal renewable energy.Biomass pyrolysis is a common biomass conversion method with high energy efficiency and abundant products.Combining concentrated solar energy with biomass pyrolysis technology can greatly enhance the application potential of biomass energy and solar energy.In this paper,experiments and simulations were carried out on the pyrolysis of three components of biomass in a micro fluidized bed directly driven by concentrated solar energy,and the influence of biomass raw material characteristics on the pyrolysis process driven by concentrated solar energy was clarified.The main contents are as follows:The pyrolysis of three components of biomass driven by concentrated solar energy were studied at the reaction temperatures of 400℃,500℃,600℃,700℃,800℃and900℃.The highest tar yield（45%）occurred in the pyrolysis of cellulose at 600℃,and the coke yield of lignin at 400℃was 61.2%.The pyrolysis gaseous products are mainly composed of CO,CO₂,H₂and CH₄.The yield of CO₂ does not fluctuate with temperature,and the three components are stable at 15%（cellulose）,14.5%（hemicellulose）and 22%（lignin）,respectively.Cellulose has the highest CO yield,36.6%at 900℃.The highest yield of H₂ and CH₄ was xylan,and the highest yield（900℃）was 3.8%and 2.2%,respectively.At 400℃,83%of the tar generated by cellulose pyrolysis is sugar,of which71.9%is levoguloglucan.At low temperature,the pyrolysis tar of lignin contains 77.3%phenols,while at high temperature,most of them are aromatic compounds such as naphthalene and anthracene.The thermostatic kinetics of concentrated solar energy driven biomass pyrolysis was study on a micro fluidized bed reaction platform.Three common gas-solid reaction mechanism functions that have good fitting effect on the pyrolysis of biomass three components are G（3）;G（4）and G（16）.The CO and CO₂ generated by cellulose pyrolysis can be described by G（16）and G（4）,and the activation energies are 19.16k J/mol and21.06k J/mol.The production characteristics of the two gases in lignin are more suitable to be described by G（16）,and the activation energies are 37.71 kJ/mol and 18.15kJ/mol,respectively.In xylan,G（4）is more suitable to describe,and the activation energies are29.08 and 33.47k J/mol.The reaction kinetics measured in the concentrated solar energy driven micro fluidized bed reactor is more inclined to the intrinsic reaction kinetics of sample pyrolysis,and the value is smaller.Based on the pyrolysis mechanism of biomass three components,a particle model of biomass three components pyrolysis mechanism under the direct drive of concentrated solar energy and a micro fluidized bed reactor model were developed.The pyrolysis model was verified in CFD simulation.The developed pyrolysis mechanism model was used to verify and compare the experimental results.By simulating the scale pyrolysis of the reactor,some abnormal results of the experiment and simulation were verified and supplemented.On this basis,some suggestions on the optimization of the reactor design were put forward.