Research On Particle Deformation And Deformation Mechanism In Biomass Thermal Pyrolysis

Biomass pyrolysis is one of the important ways to convert biomass feedstocks into liquid products bio-oil,which has been widely used.The core part of the pyrolysis process of biomass feedstock is the process conditions of the pyrolysis process.At present,there were few researches focusing on the deformation and its mechanism of raw material particles during pyrolysis of biomass,which results in a lower conversion efficiency of the biomass particles during the conversion process and wasting of resources.In this paper,a combination of experimental and simulation research method was used to study the deformation mechanism of biomass pyrolysis deformation.The purpose is to improve the coking state of the particles in the reactor,reduce industrial production costs and improve product yield.This paper has important guiding significance and provides a certain theoretical basis for industrialized production.On the basis of a horizontal tubular pyrolysis furnace reactor built in the laboratory,different types of biomass particles such as poplar wood chips,chlorella and spirulina were selected for pyrolysis experiments,the raw materials and the residue after pyrolysis were all characterized.Experiments were conducted at different pyrolysis temperatures(350-650 ℃)and pyrolysis times(10-70s),and shrinkage models were established from experimental data.The contraction rate,conversion rate,pyrolysis temperature,and other influencing factors obtained through experiments are related to the shrinkage model.Experiments were conducted by using different compositions of peanut oil,starch,soy protein powder and sodium chloride inorganic salt to simulate chlorella,spirulina and any other algae biomass materials.The pyrolysis mechanism of biomass with different composition was verified through different composition of model compounds,and the shrinkage model obtained from pyrolysis experiments of biomass raw materials was further verified.CFD fluidmechanics simulation software was used to simulate particle surface temperature under different pyrolysis conditions in the reactor,also the influence of heat transfer of the pyrolysis of biomass particles.The particle shrinkage model was further verified,and model parameters were optimized.Through experiments,the key parameters of the biomass pyrolysis shrinkage model were determined in this paper,such as biomass particle conversion rate X,the particle shrinkage d/d0 and the pyrolysis temperature T.The contraction rate correlation equation is (?),which a is a temperature-dependent function,a(10)(10)(28)cb TT2a.According to actual experimental data,the relevant parameters a,b,and c are in the range of 1×10-6-6×10-6,1×10-3-8×10-3,and-2.46~-3.88.The pyrolysis process of biomass particles was simulated and the optimum simulation temperature was determined as 873.15 K.The mass loss rate of the pyrolysis process of biomass feedstock in the reactor at this temperature was obtained.The results were in good agreement with the actual experimental data,and the shrinkage model of pyrolysis of biomass particles was optimized.The shrinkage model established in this project can accurately simulate the particle shrinkage process of biomass pyrolysis reaction under different conditions.This paper has guiding significance on the changing rules of the reaction process under different pyrolysis process conditions are obtained to design and optimize the reactor and reaction conditions.