Research On Strengthening Mechanism Of Fine Oil Shale Separation Process In Wide-scale Multi-component Pulsed Fluidized Bed

Oil resources carry the weight of the world’s economic development.In order to reduce oil dependence,many countries are actively trying to find and develop alternative energy sources.Oil shale has long been considered as a major alternative to crude oil.However,due to various factors such as the location,natural resource status and environmental awareness,the development of efficient dry benefication technology for oil shale has become an urgent need.Ideally,the pulsed gas-solid suspension system has a uniform and stable bed density.The mineral particles are completely separated in the system according to their own density;however,in practice,due to the inhomogeneity of the gas-solid inter-phase action,which leads to the simultaneous existence of bubble motion and particle remixing in the system,the system cannot maintain uniform and stable in time and space.The stratification process of mineral particles not only according to their own density differences,but also by the bubble entrainment,medium particle collision and other factors interference.Therefore,how to ensure the uniformity and stability of the pulsed fluidized bed and improve the quality of fluidization is one of the keys.In this thesis,based on the requirements of the particulate fluidization environment,the addition of fines was considered to realize the modification of the Geldart B particles,and the basic fluidization characteristics of the mixed medium were discussed in depth.It was found that:the upper limit of addition of fines to Geldart B particles was 12%-15%,and when the addition amount exceeded the upper limit,unfavorable fluidization phenomena such as channel flow and particle agglomeration appeared at the bottom of the bed;A prediction model of U_mf in pulsed fluidized bed was established;The law of bubble size,shape and quantity was systematically analyzed by combining image processing technology.A pulsed fluidized bed bubble growth model was established,which has the advantages of accurate prediction and less experimental deviation.The influence of operating gas velocity,pulsation frequency and fine particle content on the apparent viscosity of the bed was studied,and based on the viscosity test results,the pulsating energy enhanced fine particle beneficiation mechanism was revealed;A apparent viscosity prediction model of pulsed fluidized bed was established;medium resistance and bubble disturbance have a great influence on the settling behavior of large particles,so they cannot be ignored in the actual analysis process.The pulsed fluidized bed separation density model was derived on the basis of considering both,and its prediction accuracy is more accurate;On the basis of the previous theoretical study,the separating test was conducted on 6-3mm oil shale,and the effects of parameters such as pulsation frequency,fine content and operating gas velocity on the separating effect were investigated.The fine particles and appropriate pulsation frequency can improve the bed fluidization quality and reduce the bed density;By adding a certain amount of fine particles,the separating accuracy of 6-3mm oil shale by pulsed fluidized bed can be improved,and the best separation conditions were finally determined as 5%fine particle content,4Hz pulsation frequency,and 1.5Umf gas velocity;Finally,based on the machine learning random forest algorithm,the bed density change process during fluidized bed amplification was studied.It reveals the law that the prediction accuracy of the traditional model decreases with the continuous scale-up of the fluidized bed system size due to the constraints of technical theory and conditions.A new method was proposed to predict the bed density variation pattern in fluidized bed amplification process.There are 134 figures,12 tables and 229 references in this thesis.