Study On Biomass Flash Explosion Modeling Technology Based On Volumetric Elongational Deformation

In order to alleviate the problems of exhaustion of petroleum resources and white pollution,researchers have prepared new composite materials with renewable,biodegradable biomass materials and plastic polymer materials.However,biomass materials often require pretreatment before use.Among various pretreatment methods,steam explosion has become the focus of research because of its advantages of non-pollution and high efficiency.Nevertheless,the steam explosion equipment currently on the market is mainly based on cooking.Most of the steam explosion equipment is batch processing with low efficiency,while the continuous equipment is mainly screw equipment,which has strong shearing effect and is easy to lead to degradation of biomass materials.In view of the shortcomings of traditional steam explosion methods and equipment,Professor Jin-ping Qu of South China University of Technology proposed a new method for biomass flash explosion based on volumetric elongational deformation.Compared with the traditional steam explosion method,the flash explosion process is dominated by volumetric elongational deformation,which has the advantages of high heat and mass transfer uniformity,strong material adaptability,high continuous production efficiency and low energy consumption.An eccentric rotor flash explosion modeling equipment was developed based on the design of eccentric rotor plasticized transport equipment in this study.The physical model and mathematical model were established according to the gas dynamics and energy conservation of the biomass material flash explosion process.With reasonable simplification and basic assumptions,the relationship between water content,release ratio and biomass flash explosion effective energy was obtained,which provided theoretical guidance for the process debugging and optimum design of the equipment for flash explosion of biomass materials based on volumetric elongational flow.The eccentric rotor flash explosion modeling equipment was used to carry out the flash explosion experiment on three kinds of plant fibers under different process parameters in this study.And the flash explosion of cotton rod fiber(CF),wheat straw fiber(WF)and rice straw fiber(RF)was successfully realized.The microscopic morphology and chemical composition and crystallization and thermal properties of the flash explosion product were tested and characterized.The influence of various process parameters of the eccentric rotor flash explosion modeling equipment on the performance of the flash explosion products was revealed.The experimental results show that after flash explosion in the eccentric rotor flash explosion modeling device,the diameter of the cotton rod fiber,wheat straw fiber and rice straw fiber was reduced.The fibers were separated from each other and the cellulose with spiral pattern was exposed to the fiber surface.As the rotor speed increased,the degree of fiber separation increased.The increase of flash explosion temperature and water content promoted the degradation of hemicellulose and improved the crystallization performance and thermal stability of the flash explosion product.Among the three fibers,the flash explosion effect of the cotton rod fiber was the strongest,and the performance improvement of its flash explosion product was also the most obvious.The compression deformation of biomass materials during the flash explosion process was beneficial to destroying its original structure and enhancing the subsequent flash explosion effect at the place where the volume was released The best flash explosion conditions of the cotton rod fiber were obtained from the experimental results: the water content was 50%,the rotor speed was 40 rpm,and the flash explosion temperature was 140°C.The successful development of the eccentric rotor flashing modelling equipment has realized the biomass materials flash explosion based on volumetric elongational deformation.And it solves the problem of excessive shear stress of the screw equipment leading to the degradation of biomass materials,and changes the continuous flash explosion of biomass materials by using screw equipment.The new method has important guiding significance for promoting the rapid development and wide application of biomass flash explosion methods and equipment.