Fast Pyrolysis Of Biomass For Bio-oil Production And Bio-oil Refining

Rational development and high efficiency utilization of biomass energy havegreat significance for energy structure optimization, energy saving, emissionreduction and environmental protection of our country. Bio-oil could be used asengine fuel via refining. Biomass fast pyrolysis for bio-oil production is a chemicalprocess under the reaction condition of oxygen isolation, normal pressure, highheating velocity, short gas stopping period in the reactor and moderate temperature,during the pyrolysis process volatile component releasing from the biomass to formpyrolysis gas, then the stream goes through cooling unit and yields the bio-oil. In thisthesis, experimental research of corn straw pyrolysis for bio-oil is performed in thefluidized bed reaction system designed on our own. The research contains the bio-oilproduction rate and gas composition against the reaction temperature’s variety,kinetics analysis of corn straw pyrolysis, process simulation with Aspen Plus,visbreaking and hydrotreatment of the bio-oil.The results of thermogravimetric analysis of the corn straw showed: dehydratingreaction appeared before110℃; the fast pyrolysis process appeared during250~400℃,70wt%of the biomass departed away, the second reaction velocity’smaximum value appeared during330~360℃; after400℃, biomass entered slowpyrolysis process. Via the analysis of the pyrolysis kinetics model set up based onArrhenius first order reaction euqation, correlative conclusions were carried out:along with the reaction velocity’s increasing, biomass pyrolysis mechanism waschanging from the first order reaction to the second order reaction.Experimental research of corn straw pyrolysis for bio-oil was performed in thefluidized bed reactor, calculation methods of experimental parameters and mathematicmodel of the optimal reaction temperature were derived. The effect of temperature onpyrolysis was: along with the reaction temperature’s increasing, solid yield wasdecreasing correspondingly and the bio-oil yield was increasing oppositely, yield ofCO and CO2followed complementary law. At550℃, bio-oil yield reached themaximum value of42.5wt%.Process simulation model according to biomass thermogravimetric experimentwas set up by Aspen Plus, as well as the simulation model according to biomass fast pyrolysis kinetics model given by Jasen, pyrolysis conditions researching and erroranalysis. Simulation calculation results showed that the model could described thepyrolysis process for bio-oil.Concerning the poor kinetic viscosity and high oxygen content of the bio-oilderived from fast pyrolysis, visbreaking and hydrotreatment experiments weredesigned and carried out in a high pressure reactor. Under the reaction parameters of150℃and1.0MPa, bio-oil’s kinetic viscosity was decreased around45%at40℃,50℃,80℃,100℃. Took the visbreaking bio-oil blended with C10H12in1:1massproportion, then light degree hydrotreatment process was carried out under differenttemperature and pressure in the reactor, at350℃and5MPa, the oxygen content of thebio-oil was decreased to14.28wt%from48.8wt%. Simulated distillation analysisshowed refined bio-oil’s boiling points distribution was changed, the temperature of50wt%distillate is decreased with57%.