Study On Particle Flow And Discharge Characteristics In Eccentric Silos

Silos are storage and processing equipment for bulk materials,and are widely used in industries such as agriculture,mining,food,medicine and energy.The application of silos can simplify the loading and discharge process of bulk materials,save costs,facilitate mechanized and automated operations.One of the main problems is to obtain accurate discharge rate,and the difficulty lies in the complex flow characteristics of particles during silo discharge.Due to space limitations and practical production needs,eccentric silos are widely used.The changes in the position of the discharge orifice,the particle flow characteristics in the eccentric silo are further complicated,making it more difficult to predict the discharge rate.The design of eccentric silos mostly relies on traditional experiments,which cannot explore the interactions between particles or with the silo walls.The mechanism of the influence of the eccentricity of the discharge orifice on the movement characteristics of the particles in the silo and the discharge rate is still unclear.The research results can provide a theoretical basis for the design of eccentric silos and the prediction of discharge rate,and also contribute to enriching the theoretical research of granular flow.Therefore,studying the particle flow and discharge characteristics in eccentric silos has important engineering and scientific value.In this paper,the method of combining theory,experiment and simulation is used to analyze and explore the influence of the eccentricity of the discharge orifice on the flow characteristics of particles in the eccentric silo,the prediction and the change mechanism of the discharge rate,the influence of particle property parameters on the discharge flow state.The main research results are as follows:(1)The influence of the eccentricity of the discharge orifice on the macro and micro characteristics of the particle flow in the silo is revealed.The flow capacity of particles in eccentric silos is affected by eccentricity.With the change of eccentricity,the flow characteristics of particles are basically unchanged at first,and then change significantly.There is a critical value of eccentricity.(2)The mechanism of the influence of eccentricity on the discharge rate of the silo is revealed.The increase or decrease of the discharge rate is due to the change of the particle volume fraction and the vertical velocity of the particles at the discharge orifice with the eccentricity,that is,when the discharge orifice is greater than the critical eccentricity,the silo wall effect is enhanced and the sparse flow area above the discharge orifice is increased.The discharge rate model of the eccentric silo is revised and the calculation method of the critical eccentricity is established.(3)The law of the influence of particle properties on the flow state of discharge is clarified.The overall flow pattern of various types of grains in eccentric silos has similar characteristics.The physical parameters of grains have a significant impact on flow characteristics,with grains with a sphericity closer to 1 and a smaller bulk density having better discharge flow ability.The critical eccentricity decreases with the increase of the equivalent particle size.