化工学报2019，Vol.70Issue(z2)：169-180,12.DOI:10.11949/0438-1157.20190138
喷嘴结构改进及其液体射流过程颗粒团聚研究
Nozzle structure improvement and study of particles agglomeration during liquid injection
摘要
Abstract
Reducing the reaction temperature during the raw liquid injection stage will lead to different viscosities of liquid, and result in particles adhesion forming agglomeration in different sizes, this hinders heat transfer to reacting liquid and slows the cracking reactions. Therefore, particles agglomeration is an important and challenging problem for thermal cracking in fluid cokers. In the present study, the gas shroud attachment was used to improve nozzle structure, and the particles agglomeration process during nozzle injection of multi-viscosity liquid was investigated in a fluidized bed operated at different conditions based on a conductance method using a water-sand system to simulate the hot bitumen-coke system at room temperature. The results show that the porous gas shroud attachment can create an ideal dilute phase environment for liquid injection and avoid the droplets accumulation in the injection cavity and particles exchange area. Different stages can be observed during the liquid injection dispersion throughout the bed, i. e., the wetting stage, the agglomerate formation stage, and the agglomerate segregation stage. A higher gas-liquid ratio (GLR) of the nozzle provides a method to prevent particles agglomeration, and the conditions at a high gas velocity allow a higher concentration of sucrose in the liquid injection compared with that at a low fluidizing gas velocity. This study provides a theoretical basis for on-line monitoring of particles agglomeration during liquid injection to guarantee perfect contact between the atomized droplets and the bed particles.关键词
喷嘴结构/黏度/流化床/液体射流/颗粒流Key words
nozzle structure/ viscosity/ fluidized bed/ liquid injection/ particles flow分类
能源科技引用本文复制引用
杨宁,周云龙,马书生..喷嘴结构改进及其液体射流过程颗粒团聚研究[J].化工学报,2019,70(z2):169-180,12.基金项目
吉林省产业技术开发专项(2019C056-2) （2019C056-2）
吉林省教育厅"十三五"科学技术研究项目(JJKH20180438KJ) （JJKH20180438KJ）
