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

作　　者：杨宁[1,2] 周云龙 马书生[2] YANG Ning;ZHOU Yunlong;MA Shusheng(School of Energy and Power Engineering,Northeast Electric Power University,Jilin 132012,Jilin,China;National-Local Joint Engineering Laboratory of Multi-energy Efficient Energy Supply Management Technology,Jilin 132012,Jilin,China)

机构地区：[1]东北电力大学能源与动力工程学院,吉林省吉林市132012 [2]多能源互补高效供能管理技术国家地方联合工程实验室,吉林省吉林市132012

出　　处：《化工学报》2019年第A02期169-180,共12页CIESC Journal

基　　金：吉林省产业技术开发专项(2019C056-2);吉林省教育厅“十三五”科学技术研究项目(JJKH20180438KJ)

摘　　要：在重质原料液的射流阶段降低反应温度会导致液体呈现不同的黏度,促使颗粒聚集形成不同尺寸的团聚结构,阻碍了原料液的热量传递,减缓了裂化反应的速率,颗粒团聚是流体焦化反应工艺面临的一个重要而又具有挑战性的问题。选用水-沙系统模拟热态沥青-焦炭系统,利用气罩装置改进喷嘴结构,基于电导信号法测量多黏度液体射流过程的电导信号随时间的变化规律,研究不同条件下流化床内颗粒团聚过程。研究结果表明:多孔气罩装置可以为喷嘴射流创造理想的稀相环境,避免了液滴在射流空腔以及交换区域的聚集和压缩;液体射流在床层扩散过程中可以观察到不同的流化阶段,即颗粒润湿阶段、团聚形成阶段、团聚隔离阶段;较高的气液比可以有效地阻止颗粒团聚,相比于较低的流化气速,较高的气速条件允许高黏度糖水溶液参与液体射流。本研究为多黏度液体射流过程颗粒团聚现象的在线监测提供了理论研究基础,确保了流化床内射流液滴与颗粒表面的良好接触。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 

分 类 号：TK121[动力工程及工程热物理—工程热物理]