Study On Gas-solid Two-phase Dynamics In Pulsed Flow Pneumatic Conveying

Petroleum coke is a kind of cheap and highly polluted industrial raw material.It is an effective means to solve the pollution problem of petroleum coke transportation link to solve the closed transportation mode without interaction between petroleum coke and the environment.When the traditional pneumatic conveying system is applied to petroleum coke conveying,there are many problems,such as high energy consumption,particle breakage and pipe wall wear,due to the high airflow velocity required for conveying.On this basis,this thesis aimed at the physical properties of petroleum coke,in order to carry out environmental protection and energy saving short distance transportation of petroleum coke.In this thesis,a new type of energy saving pneumatic conveying method: pulse excited flow pneumatic conveying is presented.Firstly,the physical parameters of petroleum coke were studied by experiments and virtual calibration.The physical parameters such as petroleum coke density,recovery coefficient,size and shape were obtained through experiments.Through virtual calibration,combined with the central composite experiment,as well as the method of stepwise regression to build petroleum coke,petroleum coke rolling friction,static friction coefficient,petroleum coke,petroleum coke,petroleum coke-wall friction coefficient and three regression model between Angle of repose,into the real value of Angle of repose,to solve the model,so as to work out with calibration coefficient.Then the structure parameters of the pulsed flow were optimized by CFD-EDM.The structure parameters were optimized by orthogonal test,and the results of orthogonal test were analyzed by intuitive analysis and variance analysis.The results show that the order of the influence of the four structural parameters on the normalized comprehensive score of the system is: ?> L/B >S>? NB,where the influence of NB on the overall system can be almost ignored,while the other three structural parameters have significant influence.Deviation Angle is equal to 45°,eccentricity is equal to 0.4,aspect ratio is equal to 2.5,and the area is400mm2 are the optimal solution combination.Then the modulation of pulse flow field is studied by means of wavelet and POD decomposition techniques.The results show that there are a large number of small scale vortices in the pulsed excited flow field.With the development of the flow field,most of the small scale vortices have been completely transformed into large scale vortices,and the flow field tends to be stable area the action of the large scale vortices.Finally,the transport characteristics of multi-component mixed particles were studied.In the pulsed excited flow,the particles can speed up the particles to enter the stable area.In the stable area,the particles transported by the pulsed excited flow have lower dispersion coefficient and lower impact energy loss.In the process of pneumatic transport,the gas phase and the particle phase not only exchange information at low latitude,but also exchange mode at high latitude,which is particularly obvious in the pulsed excited flow.For the pulsed excited flow,the gas-solid coupling process is as follows: the decay of the original quasi-periodic and abrupt patterns of the pulsed torsion flow,and the generation of the quasi-periodic and abrupt patterns of particles.