多喷嘴对置式水煤浆气化炉内固体颗粒微观特性研究

气化炉内固体颗粒微观结构特性对气流床气化过程中熔渣、粗渣和细渣的形成具有重要影响。基于多喷嘴对置式水煤浆气化实验,对典型工况(O/C原子比为1.0)下气化炉轴向不同位置的固体颗粒进行取样,利用氮气等温吸附法和扫描电子显微镜对颗粒孔隙结构和微观形态进行研究。结果表明,气化炉内固体颗粒典型形态为不规则多孔状和规则球状,喷嘴平面有少量致密性不规则颗粒和中空颗粒。从喷嘴平面沿气化炉轴向向下,随着气化反应的进行,颗粒表面愈加粗糙,孔隙结构愈加发达。颗粒吸附曲线属于II型等温线,迟滞回线属于H3型回线,表明颗粒具有大量裂缝形孔和较连续的完整孔系统。比表面积和孔容积均随着与喷嘴平面距离的增加而增大,而平均孔径逐渐减小,在喷嘴平面附近变化幅度较大。孔结构以孔径小于10 nm的孔为主,随着气化反应的进行颗粒中小于10 nm的孔逐渐增多,而大于10 nm的孔分布状态变化不大。

Microscopic characteristics of solid pa rticle s in op posed multi-burner gasifier

The microscopic characteristics of solid particles have important influence on the formation of fluid slag, coarse slag and fine slag during entrained-flow gasification process. Based on the bench-scale opposed multi-burner (OMB) gasifier, solid particles were sampled at different axial distances along the gasifier chamber under typical operating conditions (oxygen and carbon atomic ratio at 1.0). The microscopic characteristics of solid particles were studied by using N₂ adsorption-desorption and scanning electron microscopy (SEM) methods. The results show that the solid particles are comprised mainly of porous irregular particle and spherical particle, and few solid particles generated at burner plane perform as dense irregular and hollow shape. As the gasification reaction proceeds along the axis of gasifier, the surface structure of particles becomes rougher, and the pore structure increases. The isotherms of particle samples are all type Ⅱ, and the particle samples consist of continuous and complete system of pores. The hysteresis loops are H3-type, and there are a large amount of fractured pores. BET surface area and pore volume increase with increasing distance from the burner plane, and average pore diameter gradually reduces, and larger changes occur in the vicinity of the burner plane. The mesopores less than 10 nm vary apparently and increase with increasing distances from the burner plane, while the pores larger than 10 nm are almost unchanged.