Design And Analysis Of Vehicular Sludge Dehydrator

In view of the rapid growth of sludge production,the urgency and severity of sludge treatment,combined with the related policies,by comparing the advantages and disadvantages of different types of sludge dehydrators,based on the advanced experience of domestic and foreign scholars,on the basis of meeting the design goals,the vehicular sludge dehydrator has become an auxiliary or even replacement device for municipal sewage treatment in extreme weather conditions.First of all,the existing form of water in sludge is studied,and it is concluded that only the interstitial water can be removed by mechanical squeezing in four types of water contained in the sludge.In order to solve the problem that sludge is suspended in sewage and form stable colloid,which leads to dehydration,a scheme of flocculation treatment of sewage by using environment-friendly flocculant is put forward.In order to obtain the optimum flocculant and material parameters of actual floc in municipal sewage treatment,the calculation of sludge material balance and the dosage of flocculant together with the flocculation experiment of municipal sewage are carried out.Then,on the basis of TRIZ theory and axiomatic design,the screw shaft,screw blade and filter screen are designed and calculated,and the structure form and size parameters of the sludge dehydrator are obtained.The selection of motor reducer is completed after the power calculation of the screw shaft.The design of pressure cylinder control as the material outlet of vehicular sludge dehydrator is determined by comparing the advantages and disadvantages of two different outlet devices.Next,the influence factors of sludge dehydrator are simplified,and the fluid domain is contrasted and analyzed under different design parameters,the pressure distribution in different dimensions of the press chamber as well as the interaction between material and screw are obtained,at the same time the optimum design parameters of the vehicular sludge dehydrator are obtained.The sludge density at the outlet of the dehydrator is 1112kg/m~3 by analyzing the distribution curve of the material density in the press chamber,which meets the design goal of the moisture content of sludge,less than 80%after dewatering.Finally,the fatigue life prediction of vehicular sludge dehydrator is carried out.Based on the failure condition of high-cycle fatigue,the Miner linear cumulative damage theory is used to calculate the fatigue life of the screw and the running cycles under normal working conditions are obtained.After that,the finite element method is used to establish the screw numerical analysis model based on the S-N curve of 06Cr19Ni10 stainless steel;Strength analysis is performed by using the Static Structural module to determine the stress distribution of the screw combined with the load obtained in fluid simulation.At last,Fatigue Tool module is used to analyze the screw fatigue life according to the Soderberg average stress theory.The result shows:The theoretical calculation of the screw fatigue life satisfies the design goal of 10 years service life.The maximum stress position of the screw is distributed at the connection between the screw blade and the screw shaft.The error between theoretical calculation and simulation of fatigue life is 3.62%.