| 气固环流燃烧器内颗粒流动行为 |
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| 引用本文： | 严超宇,卢春喜.气固环流燃烧器内颗粒流动行为[J].化工学报,2010,61(6):1357-1366. |
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| 作者姓名： | 严超宇 卢春喜 |
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| 作者单位： | 中国石油大学(北京)重质油国家重点实验室 |
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| 摘 要： | 针对石油焦及气化余焦的燃烧特点和流态化特性,提出了一种采用气固密相环流烧焦与快速床管式烧焦技术相组合的新型燃烧器结构。在不同操作条件(导流筒区表观气速0.772～1.674m.s-1,环隙区表观气速0.223～0.519m.s-1,装置系统的颗粒外循环强度40.8～229.4kg.m-2.s-1)及两类颗粒体系下,采用光纤测量仪对组合燃烧器环流段内颗粒流动特性进行了系统的实验研究。结果表明,两类颗粒体系的固含率和颗粒轴向速度在导流筒区、底部区和颗粒分流区床层内沿径向的分布规律为中心区小、边壁区大的环-核型分布,体现了气固流化床典型聚式流态化的非均一性特征;在环隙区,受环流段结构的影响,两类颗粒体系的固含率和颗粒轴向速度参数沿床层径向的分布相对较均匀;混合颗粒体系的固含率、颗粒轴向速度较单一石英砂颗粒体系的要小,细颗粒的加入在一定程度上能改善气固混合的均匀程度;两类颗粒体系在底部区和颗粒分流区的径向流动具有剪切破碎气泡的作用,有利于环流段内气固的充分混合接触。
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| 关 键 词： | 流化床 燃烧器 环流 气固两相 流动行为 |
| 收稿时间： | 2009-9-27 |
| 修稿时间： | 2010-2-5
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Fluidization behavior in gas-solid airlift loop combustor |
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| YAN Chaoyu,LU Chunxi.Fluidization behavior in gas-solid airlift loop combustor[J].Journal of Chemical Industry and Engineering(China),2010,61(6):1357-1366. |
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| Authors: | YAN Chaoyu LU Chunxi |
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| Abstract: | A gas-solid fluidized bed with novel structure is proposed for combustion of petroleum coke and residual coke produced in petroleum processes and coal gasification according to the combustion and fluidization characteristics.The overall circulating system of the fluidized bed mainly consists of a dense airlift loop section and a dilute riser section.The gas-solid flow characteristics are bubbling or turbulent fluidization in the airlift loop, while those are fast fluidization in the riser.The particle flow parameters, solid fraction and particle axial velocity, in the airlift loop section were measured by using optical fiber probe under different operation conditions.The superficial gas velocity ranged from 0.772 m·s-1 to 1.674 m·s-1 in the draft tube, and from 0.223 m·s-1 to 0.519 m·s-1 in the annulus.The solid circulation flux with respect to the cross-sectional area of the upper burning riser in the fluidized bed varied between 40.8 kg·m-2·s-1 and 229.4 kg·m-2·s-1.All experiments were carried out at atmospheric pressure and room temperature of approximate 25℃.Two kinds of solid particles were employed in this study.One was the sand with mean diameter of 78 μm and density of 2462 kg·s-3, and the other was a binary mixture of sand (90%，mass) and FCC powder (10%,mass).The mean diameter of the fine FCC powder was 30.9 μm and its density was 1500 kg·s-3.The experimental results show that the lateral distribution of solid fraction and particle velocity for the two kinds of particles is core-annulus or heterogeneous structure in the three regions (draft tube, bottom region and particle separation region), which embodies the common characteristic of aggregative fluidization similar to that in general fluidized beds.In the annulus, the solid fraction and the particle axial velocity exhibit a uniform lateral distribution, which is determined by the special structure of the airlift loop combustor.The solid fraction and the particle axial velocity of the binary mixture are smaller than those of the pure sand particles.The presence of fine powder in the binary mixture can improve the gas-solid mixing uniformity.The lateral movement of particles in the bottom region and particle separation region has the shearing effect for gas bubbles and makes them break into smaller ones, enhancing the gas-solid contacting. |
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| Keywords: | fluidized bed combustor loop flow gas-solid two phases flow behavior |
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