Research On Three-dimensional Characterization And Permeation Of Coal-Based Porous Carbon

With the entry of human society into the industrial age,the problem of environmental pollution has always intensified with the development of all walks of society and even science.The coal-based porous carbon is a porous material in which coking coal particles are used as a basement and coal pitch is bonded and fired together.As a typical porous medium,there are a large number of microscopic pores inside the coal-based porous carbon,and the large porosity factor has made it widely used in the field of adsorption purification.In this paper,the true pore structure of coal-based porous carbon was characterized,the structure and the variation of coal-based porous carbon pore appearance was obtained.Then,the flow of seepage in different pores was simulated by k-? turbulence model,and the influence of pore structure on seepage flow in coal-based porous carbon pores were analyzed and its mechanism was studied,in order to optimize the penetration effect of porosity.This thesis has certain significance for optimizing material related properties.(1)3D X-ray microscopic imaging system was used to scan the coal based porous carbon sample,and the 2D gray image was obtained.Then,Image processing was carried out by Image J software,and gray information of pore structure was acquired from the image.The boundary of the irregular phase in the image was detected and the largest regular area of the sample was divided.The threshold was divided by iterative method.The pore structure in the 2D images was characterized by Image J software based on the gray value and 2D characterization of pore structure was obtained.(2)3D reconstruction of pore was carried out based on high-precision 2D CT images,and 3D pore structure was characterized by Avizo software.The results of the characterization are compared with the 2D characterization.The 200×200×200 representative elementary volume was selected to derive the 3D structure.Repairing and meshing structure by ICEM software,the 3D model of coal-based porous carbon based on real pore structure is obtained.(3)One-way seepage simulation based on the standard k-? model of the 3D model by Fluent software.The results show that the seepage flows first into the long and narrow uncurved connected pore channels.The seepage velocity increases with the decrease of the pore size of the pore section and decreases gradually as the flow field diffuses to the wall surface.(4)Then,the multi-direction seepage simulation of the pore model was carried out,and the results obtained were compared with the unidirectional seepage flow.It can be seen that due to the increase of pressure outlet,the seepage flow would be more widely distributed in each pore,resulting in a slightly higher utilization rate of the multidirection flow on the pore structure of the model than that of the unidirectional flow.