GIEC OpenIR  > 中国科学院广州能源研究所
喷流-移动床的流体力学特性研究
陈平
导师陈勇
2000
学位授予单位中国科学院广州能源研究所
学位授予地点中国科学院广州能源研究所
学位名称硕士
学位专业热能工程
关键词喷流-移动床 最小喷动速度 喷动压降 颗粒循环流率
摘要RDF是一种城市生活垃圾经过分选、粉碎、干燥、混合及成型等工艺制成的新型固体燃料,它具有尺寸、密度和物性均匀、热值高、易储存、输运等优点。为实现RDF的有效和洁净燃烧,本文提出了一种新型反应器:喷流-移动床式RDF热解燃烧炉。该装置主体有两部分构成:热解室和燃烧室 。其原理是:RDF首先在热解室中在贫氧条件下部分燃烧并热解,热解产生的气体再进入燃烧室中在二次风作用下充分燃烧。作为热态实验的必要准备,我们首先在冷态实验条件下对喷流-移动床的基本流体力学特征进行了研究。本文在内径为190mm的有机玻璃喷流-移动床中,利用绿豆、小米、粗沙和尼龙棒等物料对不同床层高度、不同喷动气量、不同辅助气量下的喷流-移动床的最小喷动速度、喷动压降、操作相图及颗粒循环流动速度分布进行了研究,为热态实验设计和操作的一些重要参数提供了较可靠的数据基础。实验发现:(1)最小喷动速度随床层高度增加而增大,随颗粒密度、粒径增加而增大,随辅助气量增加而减小。加入辅助气量,在尚未达到喷动流化状态下,喷动所需总气量要比标准喷动床大而比最小流化所需气量小。(2)改变床层高度和辅助气量,可以看到喷动压降随床层高度和辅助气量增加而增大。喷动压降与床层高度的关系可用方程(2-5)来表达。(3)改变辅助气量和喷动气量,可观察到物料在床中存在四种不同的流动状态:固定床、稳定喷动床(充气喷动床)、射流流化床和脉动喷动床(喷动流化床)。(4)颗粒循环流率随喷动气速、辅助气量增加而增大;在轴向随床层高度降低而减小,大约在160mm左右减到最小而又增加;床层高度对颗粒循环流率没有影响。(5)对环流区中颗粒的流动,纯动力学模型给出了较满意的结果;而喷动区中,流体和颗粒的运动可利用气固两相流模型来描述。
其他摘要Refuse Derived Fuel (RDF) is a new-type solid fuel that is made by sorting, crushing, drying, blending and molding from municipal solid waste. It has following characteristics: 1) homogeneous dimension and physical-chemical characters; 2) high heating value (about 2/3 heating value of standard coal) and high volatile (about 70%); 3) easy to store and to transport. To achieve efficient and clean combustion of RDF, a spouting-moving bed reactor is proposed. It includes two chambers: pyrolysis chamber and combustion chamber. RDF was firstly pyrolyzed with scarce air and then the volatile combusted completely in combustion chamber with secondary air. As the preparation of high temperature experiment, the hydrodynamics of spouting-moving bed are firstly investigated at ambient temperature in a 190mm I.D. conical cylindrical perspex column. Our research mainly focuses on the following issues: (1) The minimum spouting velocity with different operation conditions and different bed materials; (2) The spout pressure-drop in the reactor (3) The region of steady spouting (4) The solids circulating flow rate with different operation conditions and different bed materials; According to the cold model test result, part of the parameters of hot model test reactor is determined. The results of cold test follow as: (1) Minimum spouting velocity increases as bed height, particle diameter and particle density increase, decreases as auxiliary gas velocity increases. When auxiliary gas is added, the total gas volume entering spouting-moving bed is larger than that of typical spouted bed but less than the minimum fluidizing velocity. (2) The spout pressure-drop will increase as bed height and auxiliary gas flowrate increase. The relationship of spout pressure-drop and bed height can be described by the Equation (2-5). (3) When auxiliary gas velocity and spouting gas velocity are varied, four different flow regimes are identified and mapped, which are fixed bed, steady spouted bed (spouting with aeration), jetting fluidized bed and spouted bed with pulsation (spout-fluid bed). (4) Solids circulation mass flow rate increases as spouting gas velocity and auxiliary gas velocity increases. At axial direction, solids circulation mass rate firstly decreases as bed height decreases until it reaches the minimum at 160mm (a little above the joint of column and cone) and then increases as bed height decreases the bed height has no effect on the solids ciuculation mass flowrate. (5) The particle flow pattern in the annular is successfully described by a pure dynamic model; the particle and gas flow pattern in the spout can be described by gas-solid phase flow model.
页数63
语种中文
文献类型学位论文
条目标识符http://ir.giec.ac.cn/handle/344007/3843
专题中国科学院广州能源研究所
推荐引用方式
GB/T 7714
陈平. 喷流-移动床的流体力学特性研究[D]. 中国科学院广州能源研究所. 中国科学院广州能源研究所,2000.
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