Design And Performance Study Of Secondary Crushing Device For Hydrate Slurry

As the 173th type of mineral in the China,natural gas hydrate is a highly efficient and clean energy source with abundant reserves.It is also an important direction of global energy developing in the future.Solid fluidization mining is a new idea for safe,green and efficient exploitation of submarined non-diagenetic hydrate in China.The re-crushing is the key that if hydrate slurry can be fluidized and the smooth implementation of subsequent separation process.As for the hydrate slurry particle after first extraction and recovery,this paper designed a method and device of re-crushing in the pipeline based on the theory and method of rock breaking.Through the combination of simulation analysis and experimental verification,the influence of parameters such as the number of cutter teeth,the diameter of the cutter teeth and the rotation speed of the motor on the re-crushing effect were studied.The main designing parameters of rotary cutting re-crushing device that meets the command of solid fluidization and subsequent separation process were determined primarily.Also,it built a foundation for the design and optimization of the follow-up natural gas hydrate re-crushing device.The main research work is as follows:(1)Based on the investigation of crushing theories and institutions at home and abroad,this paper provided a re-crushing method that rotary cutting hydrate slurry in the transporting pipes.This paper completed the structure design and three-dimension model building of the re-crushing device,and checked the main components in the strength.(2)Based on the solid fluidization mining working condition,the simulated analysis of rotary agitation fluid and particle moving rule in the crushing cavity was accomplished by coupling Fluent and EDEM as for designed re-crushing device.Therefore a set of method that can assess the performance of re-crushing device was built,and it can provide basis of optimizing related structure parameters in the crushing cavity.(3)Based on the established simulation models and analysis methods,the studies in the influence of the number of teeth,the diameter of the tool teeth,and the angle of the knife teeth on the flow field motion rule were carried out through orthogonal design,and the structure optimization of the re-crushing device was completed based on it.For the optimized structure parameters of the re-crushing device,the studies in the influence of the moor speed and inlet velocity of the crushing cavity on the particle moving speed and position were carried out.Finally,the optimal rotation speed and flow velocity range of the device structure were found and it can provide technology and equipment support for the solid fluidization process.(4)In order to verify the feasibility of the proposed crushing method and device,a set of secondary crushing experiment program was designed and an experimental bench was built.The experimental research on the crushing rate and particle size distribution after crushing was carried out under different conditions such as the number of cutter teeth,cutter and rotation speed.The experiment showed that the crushing rate of single cutter in one time can reach more than 60%when the particles passed the re-crushing device,and the crushing particle size decreased by 60%.So the experiment results verified that the crushing method and device can crush the large particles in the hydrate slurry effectively.The variation rules of the crushing rate and particle size distribution under different parameters were basically consistent with the simulation results.In summary,the principle of re-crushing of hydrate slurry proposed in this paper is feasible.The device designed is simple in structure and highly efficient in crushing.The optimized re-crushing device can provide slurry with different particle size distribution for the fluidization and subsequent separation of slurry in hydrate solid state fluidized production.The set of simulation models and analysis methods that established can provide new ideas for the design and optimization of re-crushing device in hydrate solid state fluidized production.