Design And Optimization Of Fluidized Reactor Adapting To Fine-grade Rich Titani?m Material

In foreign countries,the preparation of TiCl4 by fluidizing chlorination is a mature technology,It has more advantages than molten salt chlorination.However,due to the blockade of foreign technology,there is only one company which can prepare the TiCl4 by fluidizing chlorination in China.The main reason behind is that the high titanium slag in our country always contains high content of the calcium and magnesium,which make the gas distribution plate easy to be blocked in the process of fluiding chlorination.Some domestic scholars use acid leaching method to remove the harmful impurities such as calcium and magnesium.At some time,the particle size will be fine.As we all know,there is a strong force between the fine particles so that adhesion and coalescence occurs easily.In process of fluidization operation,channel flow,slugging or regiment is easy to form,which reduces the gas-solid contact efficiency,reaction kinetics conditions are not sufficient,affecting the gas-solid interface reaction process and efficiency of the reactor.In this study,the main mission is to solve the problem of high elutration rate and poor fluidity,the physical and chemical properties of fine grained rich titanium materials were analyzed and the rational furnace structure suitable for fine grained rich titanium material was designed and improved.Moreover,the suitable operating parameters of the furnace should be found.All above could provide reliable technicial support for the eqiupment technologyof the fuidizing chlorination.Firstly,the fluidity performance parameters of fine-grained hightitanium raw materials were measured by powder comprehensive tester.The particle size composition of fine-grained hightitanium raw materials was analyzed by laser particle size analyzer.the chemical composition and ore structure of fine-grained hightitanium raw materialscould be observed by means of the SEM and XRDAccording to the basic properties of fine-grained hightitanium raw materials,the fluidization operating velocity interval and circulating fluidization velocity of fine grained titanium rich material are calculated and these results aretested by the method of the experimental verification.In order to improve the fluidity of the fine-grained high titanium raw materials,the appropriate size range and the appropriate proportion of petroleum coke were added to the experimental process;The original fluidized bed model was optimized,and the circulating fluidization system,tangential two airinjection system,tangential air inlet gas distributor and bottom slag discharge system were added.The numerical simulation method was used to simulate the fluidized bed.From the macroscopic view,inthe radial direction,the bed shows the nuclear structure,which means that the center and edge of the structure arestrong.but in the axial direction,it shows the distribution pattern of the dilute and concentrated.This is in agreement with the experimental results.The pressure in fluidized bed is fluctuation in the start-up stage,whileafter stabilization,the pressure fluctuation is small.Three-dimensional simulation of the tangential inlet effect shows tangential air into the furnace can form tangential rotation flow.besides,the tangential velocity near the wall has a lager value.It can be seen that when the tangential velocity increases,the movement of the particles in the tangential direction will be strengthened,which will prolong the residence time in the bed and improve the reaction efficiency.Cold and hot state experiments were done on the optimized fluidized bed.The experimental results show that with the increase of the bottom flow rate,the elutriation rate increases gradually;Tangential secondary air injection can be a good way to reduce the elutriation rate,and found the best secondary air velocity.By adding a recirculating fluidization system,the fine-grained hightitanium raw materialsfrom the riser can be reintroduced into the riser,It can be a good way to reduce the elutration rate,the results is far less than the target value,At the same time,the bottom fluidized flow can be realized normal circulating fluidization in a wide range;The results of hot sate experiments show that with the increase of temperature,the elutration rate is gradually increased,but it is still within the reasonable requirements(1%).