Research On The Influence Of Moisture Content On The Densification Of Sand Shrubs Particles

With the increasing energy consumption in China,it is urgent to accelerate the development of the new energy industry.As a new renewable energy source,biomass energy will formally become an important option to replace fossil energy.Salix is one of the first-selected tree species for windbreak and sand fixation in northern my country.It has the characteristics of high calorific value,flat stubble and rejuvenation.Its branches have become important raw material resources for the development of biomass molding fuels.Therefore,it is of great practical significance to study the dense forming technology of Salix.Based on the discrete element method,this paper uses the software PFC3 D to facilitate the treatment of discontinuous media mechanical problems,so that the particles are not limited by the amount of deformation,and to reveal the inter-particle fracture and the effect of moisture in the adhesion during the compacting process of Salix.The model was established.Under the conditions of temperature 100℃ and pressure 100～180KN,single factor pressure compression simulation experiment and three groups(group A,group B,group C)compression simulation experiment with different water content were done.The main research was The particle movement,force chain evolution mechanism and energy change law are analyzed with reference to the simulation results.The results show that:(1)The influence of pressure on the compacting of Salix granules: The main influencing factor of the speed and displacement of the particles is pressure.From the change of speed and displacement,the direction of the force can be analyzed.(2)The influence of moisture on the compacting of Salix granules: It can effectively enhance the peak compressive strength of the model,increase the strength of the force chain,and prevent some weak force chains from being damaged to form fissures,thereby reducing the number of fissures;The particles can be fully extended,and the lignin can be softened to act as a binder;It can reduce boundary energy loss;It can act as a lubricant to effectively reduce the friction and energy loss between particles;It can generate sufficient capillary force on the surface of the particles to reduce the excess stress on the particles.(3)Characteristics of energy evolution in the process of dense forming of Salix granules: For the entire energy system,the proportion of kinetic energy is very small,and the change of kinetic energy is related to the gap and pressure between particles,and is linearly related to the strain of the whole particle.As the amount of strain gradually increases,the growth trend of bonding energy slows down,and the proportion of other energies gradually increases,such as friction energy,heat energy,and other dissipation energy.Before the compressive peak strength,the energy is mainly the accumulation of bonding energy and the release of other energy(for example: heat energy,kinetic energy,etc.);After the compressive peak strength,the internal structure of the Salix model undergoes a fundamental change,and the bond The proportion of energy in the boundary energy gradually decreases,and the energy dissipated begins to increase.In order to reduce energy loss,the strain value should be controlled within a smaller range.The use of particle flow discrete element method to simulate the dense forming of Salix provides a new idea for biomass research and provides certain guidance for the actual production of dense forming of Salix.