孔隙结构特征对焦炭高温抗拉强度的影响

采用压汞仪测量焦炭与CO₂或H₂O反应后的孔隙结构特征,研究孔隙率、平均孔径、比表面积及孔径分布对焦炭高温抗拉强度的影响规律.焦炭孔隙率和平均孔径随反应率升高而增加.平均孔径小于30μm时气化反应以造孔为主,比表面积随反应率升高先增后减,大于30μm时以扩孔为主,随反应率升高而减小.与CO₂相比,H₂O反应后焦炭平均孔径小,比表面积大,抗拉强度高.焦炭抗拉强度随孔隙率和平均孔径增加而降低,平均孔径小于30μm时抗拉强度随比表面积增加而降低,大于30μm时随比表面积减小而降低.焦炭中小孔数量越多抗拉强度越高,大孔数量越多抗拉强度越低.相同反应率下,H₂O反应后焦炭中小孔数量增加,比表面积大,有利于保护气孔壁结构,抑制高温抗拉强度的降低. 

Influence of pore structure features on the high temperature tensile strength of coke

Through measuring the pore structure features of coke reacted with H₂O or CO₂ using a mercury porosimeter,the influence of average pore size,specific surface area and pore size distribution on the high temperature tensile strength of coke were studied in this paper. It is found that the porosity and average pore diameter of coke increase with the increase of reaction degree. When the average pore size is less than 30 μm,the gasification reaction is mainly pore-creating,and the surface area of coke increases firstly and then decreases with increasing reaction degree; but when the average pore size is more than 30 μm,the gasification reaction is mainly pore-expanding. Compared with CO₂,coke reacted with H₂O has a smaller average pore diameter,larger specific surface area and tensile strength. The tensile strength of coke decreases with the increase of porosity and average pore diameter. At an average pore diameter smaller than 30 μm,the tensile strength decreases with the increase of specific surface area; but at an average pore diameter larger than 30 μm,the tensile strength decreases with the decrease of specific surface area. The small pore increases the tensile strength of coke,while the large pore decreases the tensile strength. At the same reaction rate,coke reacted with H₂O has a large amount of small pores and large specific surface area,which are conducive to protect the structure of the air pore wall and to prevent from the reduction of tensile strength at high temperature.