Study On Pyrolysis Kinetics And Mechanism Of Biomass Under Magnetic Field

Biomass is the only carbon-containing renewable energy resource that can be used to produce liquid fuels on a large scale.As a mainstream thermochemical conversion technology,rapid pyrolysis liquefaction of biomass can efficiently convert solid biomass into liquid fuel,bio-oil,which is easy to store,transport and has high energy density.At present,the bio-oil produced by biomass pyrolysis liquefaction process has some shortcomings,such as high moisture content,high oxygen content,high viscosity,low calorific value,low PH,complex components and unstable properties,which limit its application as high-grade power liquid fuel.It is necessary to optimize and innovate the existing biomass pyrolysis process and theory.In this paper,biomass-rapeseed was used as raw material to study the process of magnetized rapeseed pyrolysis,the process of rapeseed pyrolysis in magnetic field and the process of magnetized rapeseed pyrolysis oil in magnetic field.It is objective to find out a new way to improve the quality of pyrolysis products by optimizing the distribution of pyrolysis products.The main findings of this paper are summarized as follows:(1)In the experiment of pyrolysis of rapeseed after magnetization,it was found that the distribution of pyrolysis products of rapeseed after magnetization for a period of time in 0.45 T magnetic field was similar to that of non-magnetization,and the physical and chemical properties of the pyrolysis oil had no obvious change.The magnetic field has no effect on the structural characteristics of rapeseed,resulting in the change of pyrolysis products.(2)In the magnetization pyrolysis experiment,the pyrolysis temperature curve and cumulative gas production of Rapeseed under magnetic field environment have obvious changes.Under the influence of thermal magnetic convection,the heat transfer and heat transfer enhancement in the furnace lead to faster pyrolysis rate and more thorough pyrolysis reaction.The specific performance is that with the increase of magnetic induction intensity,the carbon yield decreases and the liquid yield basically maintains unchanged,the gas yield increased.The magnetic field promoted the pyrolysis of rapeseed and the reaction was more complete,which promoted the transformation of pyrolytic carbon to the direction of pyrolysis gas.On the other hand,the viscosity of pyrolysis oil is obviously reduced,the organic macromolecules in pyrolysis oil are reduced,and the organic small molecules are increased.Taking four Al-Ni-Co magnets in the furnace as an example,the 3D simulation of the magnetic field in the furnace is realized by Maxwell software.The analysis shows that the magnetic field in the furnace changes from small to large from the edge of the furnace to the center of the furnace,and then from large to small.(3)In the experiment of magnetized pyrolysis oil,it was found that the physical and chemical properties of pyrolysis oil changed at different time.The viscosity of pyrolysis oil decreased gradually with the increase of magnetization time.After magnetization for 4 hours,the viscosity decreased by 29.8%,and the water content decreased first and then increased with the extension of magnetization time.According to the change of chemical composition of pyrolysis oil in different time periods,the possible chemical reaction pathway and corresponding products of pyrolysis oil in magnetic field were deduced.It is speculated that the possible chemical reactions include nitrile hydrolysis,olefin addition reaction,reaction of toluene formation,esterification etc.