Investigation On The Pyrolysis, Combustion Mechanism And Property Modification Of Acid-hydrolytic Biomass Residue

The stress of conventional energy depletion and environmental pollutionpromoted the extensive utilization of biomass energy. And producing liquid fuels suchas ethanol, furfural and levulinic acid through biomass hydrolysis process, is one ofthe important approach of biomass energy utilization. Hydrolysis process operateswith the environment temperature of200oC or so, which needs energy consume.While most of the cellulose and hemicelluloses are broken down, a large number oflignin residues will be produced. This kind of residue gets the the characteristics ofhigh calorific value, moisture content as well as acid value. In order to improve thebiomass utilization and reach the purpose of improving the overall energy efficiency,this paper puts forward the idea of using the high calorific value residues as fuel andproviding heat for hydrolysis process to maintain its continuous operation. This willnot only solve the problem of energy consumption during the hydrolysis process, butalso increase the biomass utilization. Thus, it can lead to a reduction of pollutioncaused by hydrolysis residue emission.Generally the hydrolysis process operates under the acid environment, so thehydrolysis residue is also acidic, this will give rise to a strong corrosion in thehydrolysis residue combustion equipment. Meanwhile, high acid content also make itimpossible to meet emissions standards during combustion. Therefore, a typicalsample of acid biomass residue-furfural residue is chosed in this paper, the methodsof both theoretical analysis and experimental study are adopted. With a depth study ofthe biomass residues pyrolysis combustion characteristic, certain theoretical basis aremade to give recommendations for the utilization of the hydrolysis residues. Based oninvestigations of acid residue regulation made by other researchers, an approach ofadding CaO is proposed.This paper mainly focuses on experimental study of the contents as follow:First, by changing the material particle size, moisture content, heating rate andother factors, the thermo gravimetric (tg)-differential thermal coupled apparatuswere used to conduct the furfural residue pyrolysis and combustion experiments respectively, and the influence of different factors on the pyrolysis was analyzed.Meanwhile, combustion process, the pyrolysis characteristic and combustion heatphysical and chemical properties of furfural residue were confirmed. Then, by addingCaO the acid value of furfural residue was adjusted, both pyrolysis and combustionexperiments were carried out again. Through the comparison and analysis, theinfluence of CaO content in pyrolysis raw materials during the combustion processwas valued. Finally, through the analysis of moisture content and the moldingpressure of furfural slag forming, the mechanism of furfural slag forming process aswell as the influencing factors were investigated; thereafter, the pyrolysis andcombustion tests on furfural slag particle were conducted to analyze the effect ofmolding pressure.,The research results show that the increase of raw material particle size can leadto a reduction in pyrolysis temperature, while high temperature after pyrolytic processwould widen the interval of weightlessness peak, as well as increasing the maximumweight loss rate; Within0~0.3mm, the particle size has little influences on theignition temperature, combustion temperature and maximum combustion rate, whilethe particle size is larger than0.3mm, there appeared a temperature jump phenomenaduring combustion process, which demonstrates accelerated pace of combustion.Increasing of moisture content and heating rate can lag various of typical workingpoint in pyrolysis process, raise not only pyrolysis initial temperature and finaltemperature, but also the combustion ignition temperature and burnout temperature,which demonstrates decelerated pace of combustion. Approach of adding CaO haslittle influences on parameters of pyrolysis initial and final temperature, combustionignition temperature and burnout temperature, while the increase of adding quantitydecreases pyrolysis and combustion reaction rate greatly. Furfural residue with theMoisture content of6%~10%, can meet the requirements of forming pellet fuelunder1mpa pressure. Increasing of molding pressure can lag the typical point ofpyrolysis process, raise the pyrolysis initial and final temperature, which leads to areduction of the maximum pyrolysis rate. Molding fuel has a higher combustion ratecomparing with molding material, appearing the temperature jump phenomenon. Also,the ignition temperature and burnout temperature will increase.