| The “China manufacturing 2025” plan proposes the vigorous development of intelligent and green manufacturing and other advanced technologies;moreover,it emphasizes to solve the problems of low product grade,low utilization efficiency of resources and energy and environmental pollution.Bulk storage equipment belongs to the equipment manufacturing industry infrastructure.It is extensively applied in coal,food,chemical,storage and logistic fields.It reflects the development level of the equipment manufacturing industry and other related industries.The large flat-bottomed silo is one of bulk storage equipment,and exhibits high space utilization,precise control,greenization and security.It is relative lagging for China's high-end intelligent silo equipment development,the paucity of research on the conveying mechanism of the rotation/revolution free screw conveyor,discharge by screw-assisted,in a large flat-bottomed silo is one of the main reasons.For the first time,this study investigated the conveying mechanism of the rotation/revolution screw conveyor on a free surface,discharge by screw-assisted,in a large flat-bottomed silo through a combination of theoretical analysis and simulation.The research results and innovations are as follows:1.Based on the kinematics and dynamics of the bulk material on the flight,and by the rotation/revolution characteristics of the screw conveyor,a mathematical model of the horizontal axial velocity of the material on the screw flight was established.Through an EDEM simulation,a mathematical model of the horizontal axial conveying speed of the material along the free rotation/revolution screw conveyor length was constructed,and correction factor k = 0.2–0.5 was proposed.The problem of replacing the axial velocity of the material on the flight with the horizontal axial conveying speed of the material was solved.2.Based on analysing the mechanism of the free and screw-assisted flowing of the ideal bulk material and an EDEM simulation.A volume calculation scheme for material flow was developed,that is to say,the triangular stagnant zone formed by material flowing was used as a basis for the calculation of the minimum amount of transportation and volume of the material flowing from wedge and circular bodies.A mathematical model of the material volume by screw revolution and the screw rotation was built separately.By the rotation/revolution characteristics of the screw conveyor,a mathematical model of the volume of the material transported by the rotation/revolution free screw conveyor was likewise established,it provide a basis for the calculation of the material filling coefficient.3.After investigating the horizontal axial conveying speed and conveying volume of the material,and the material filling coefficient was analysed,a mathematical model of the average throughput was established with the rotation/revolution free screw conveyor.The accuracy of the mathematical model of throughput was verified through a simulation and experiment.It is a theoretical basis for the mathematical model to control the screw throughput.4.According to the rotation/revolution characteristics and transport properties of the screw conveyor,the matching relationship between the operating parameters of the screw conveyor is established.The quantity transported was used as the optimization target,and rotational/revolving speed was matched by using immune optimization theory,and the self-simulation and experiment verified the rationality of the screw operation parameter matching.The height of circular truncated cone was considered as the control value,and the lifting and rotation/revolution control of the screw conveyor and its driving idea were presented to stabilize and continuously control the material flow during the discharge process.The idea is a theoretical guide to apply to the engineering project.In this study,the key problem of conveying mechanism of the rotation/revolution free screw conveyor operation for discharge in a large flat-bottomed silo was solved through mechanism analysis,theoretical modelling,simulation analysis and experimental verification.The findings can be directly applied to China's high-end intelligent silo equipment research and development,design and manufacturing and could help fill gaps in the current research field.This study presents theoretical and practical significance in enhancing the technical level and application ability of modern warehousing equipment in China. |
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