Design And Analysis Of Drying System Mounted On Multifunctional Dredging And Dewatering Vehicle

Drying system serves as an important device for multifunctional dredging and dewatering vehicle.It aims to achieve sludge reduction and solve the time consuming and low efficiency problems of traditional dredging vehicles.A new vehicle-mounted drying system is designed in this thesis with hot air drying method which has the advantages of high drying intensity,fast drying,high thermal efficiency and compact structure,etc.So municipal pipes,sewers can be dredging fast.Firstly,the material balance,heat balance and stirred tank volume are calculated based on design requirements using Drying Apparatus Design Manual.After that,horizontal and vertical layout schemes are put forward according to the overall layout requirements of vehicle.By contrast,vertical layout scheme is an optimal scheme considering its characteristics.Then the key components including shaft,stirring teeth,deflector and unloader are designed.The appurtenances including air heaters,centrifugal fan,radiator and gear-motors are selected based on its calculation.Secondly,computational fluid dynamics model was established based on Fluent.The optimum installation angle and the optimum number of deflector are determined through single-phase flow analysis.By comparing the rotation direction,the conclusion that counter-rotating with deflectors' direction could get better cyclone is obtained.Besides,stirring tooth arrangements are evaluated using the MRF model by comparing the velocity and its components,it turns out that cross staggered arrangement is better.Meanwhile,by comparing the flow direction with different number of stirring teeth,the optimum number of stirring teeth is determined.Thirdly,numerical simulation of two-phase flow is calculated with the DPM model.The optimum inlet velocity is selected by researching the effect of inlet velocity to particles' trajectory.The transient temperature field distribution and movement of particles are obtained by means of multicomponent particle definition method and sliding mesh model.Drying process can be divided into three phases,including heating phase,fast drying phase and slow drying phase.The influence to drying of inlet temperature and inlet velocity are calculated,it turns out that speed at 16m/s is inflection point,and comes the conclusion that the relationship between drying effect and inlet temperature is linear.Fourthly,the strength of the key moving parts is verified through FSI model.The maximum stress and maximum strain are obtained based on air pressure and thermal stress.After that,the modal analysis which comes the conclusion that the main vibration frequency is above 70.81 Hz is conducted,so the excitation frequency can effectively avoid the inherent vibration frequency.Finally,two-dimensional drawings,trial manufacture and assembly work of drying system are completed according to the final structure.These work lay the foundation of mass production.The key technology and innovation of vehicle-mounted drying system are listed as follows: the highly integrated structure and the utilizing of radiator heat can solve the overall layout and energy saving problems.What's more,fluid analysis software which can get reasonable structure parameters,material movement and drying characteristics can reduce the cost of testing and provide a guideline for optimization.Technical difficulty is how to determine particles' properties and accurately simulate the drying process.