Structure Analysis And Optimization Of Agitator Shaft Stabilizer

Stirring tanks are widely used in coatings,medicine,building materials,chemicals,pigments,resins,food,scientific research,etc.It is a device for mixing,blending,homogenizing and other operations.Reasonable design of equipment structure,advanced technology and simple operation are the keys to safe operation of equipment.With the development of large-scale and high-parameter stirring tanks,the safety and reliability of equipment has become more and more important.Some failures may occur,such as seal failure,transmission member strength failure,stiffness failure,fatigue failure,resonance.Take,for example,large fermenter used in the fermentation industry has complex internal structure and the external foundation is huge.It is not only difficult to manufacture and install,but also has complex failure factors.In addition,the failure factors of this equipment are complicated,especially due to the large number of fermenter transmission components and the relatively long length of the transmission shaft.The bottom bearing and the intermediate bearing are installed,which becomes the dead zone of the stirring reaction kettle,which is easy to cause pollution to the products and seriously affects the product quality.Therefore,it is urgent to adopt a reasonable structure to avoid these effects.The literature shows that foreign fermenters rarely install intermediate or bottom bearings,and the stabilizers are often used to reduce the bending vibration of the agitator shaft.Not only the stable effect is good,but also the manufacturing is simple,the installation is convenient,and the dead zone pollution can be effectively avoided.Therefore,it has been widely used,but its theoretical research has not been reported in detail.The agitator shaft stabilizer has also been counterfeited in China,and it is still in the experimental stage.Therefore,it is of great application value to study the stability of the stirring shaft stabilizer and the influence on the stirring characteristics.Based on the research results of the agitator shaft stabilizer at home and abroad,this paper designs four stabilizers with a ratio of stabilizer diameter to agitator diameter of 0.7 for the six straight-blade open turbine agitator used in the experiment.The heights of the four stabilizers are 30 mm,40mm,50 mm,80mm.This paper studied the effect of the stabilizer on the stability of the agitator shaft,the flow field characteristics during the agitation reaction,and the power loss of the agitation system.This study used an eddy current sensor to design,install and commission a set of agitator shaft deflection measurement system based on MCGS(Monitor and Control Generated System).The system monitors the deflection of the agitator shaft in real time during the rotation of the agitator shaft,and uses the system to measure the deflection of the agitator shaft before and after the installation of the stabilizer.In addition,it analyzes the effect of the four different height stabilizers designed on the running stability of the mixing shaft.The experimental results show that when the speed is lower than 280 rpm,the stabilizer with a height of 40 mm has a relatively stable effect,and the stability effect varies with the speed;the stability of the stabilizer with a height of 30 mm,50 mm,and 80 mm is not obvious.PIV(Particle Image Velocimetry)technology was used to measure the flow field in the stirred tank before and after the stabilizer was installed,and compared with the flow field when the stabilizer was not installed.This study analyzed the effects of different height stabilizers on the flow field in the stirred tank from the aspects of fluid flow pattern,relative motion between fluids,and damage of cylindrical rotating zone.As the height of the stabilizer increases,the influence of the stabilizer on the flow field will become larger and larger.It will gradually change the flow pattern of the fluid,mainly transforming the fluid from a tangential flow to a radial flow and then to an axial flow.Combined with the results of the deflection test,it is concluded that the radial flow of the fluid in the flow field can produce an effective dampin65 g effect on the stabilizer.However,as the rotational speed increases,the flow pattern of the fluid gradually changes from tangential flow to radial flow,so the stabilizer has its maximum applicable speed.The torque during the rotation of the agitator shaft was measured by a torque coupler.According to P = T * n / 9550,the agitation power before and after the stabilizer was installed was calculated,and the trend of power with speed was obtained.When the rotation speed is 20 rpm~180 rpm,the installation stabilizer has no obvious influence on the stirring power;when the rotation speed is 180 rpm~250 rpm,the installation stabilizer will increase the stirring power;when the rotation speed is greater than 250 rpm,the installation stabilizer will reduce the stirring power.The study used the finite element software ANSYS to perform the structural analysis of the agitator shaft system.This experiment compares the results of the analytical simulation with the experimental measurements,without the stabilizer installed.The results show that the analytical simulation results are consistent with the experimental measurement results.