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题名	U阀流态化排料数学模型的建立
作者	彭莉
学位类别	硕士
答辩日期	2012-06-04
授予单位	中国科学院研究生院
导师	朱庆山 ;    李洪钟
关键词	U阀 排料速率 数学模型
其他题名	Hydrodynamic Modeling of U-valve under Fluidization Discharging Mode
学位专业	化学工程
中文摘要	循环流化床是一种处理多相反应的高效反应器，广泛应用于能源、资源领域。返料系统是循环流化床的重要组成部件，是循环流化床实现连续运行的关键。返料系统一般由立管和返料阀组成，由于U阀具有可靠性高、输送压力低、易于实现负荷调节等优点，因而成为目前工业中应用最为广泛的一种返料装置。影响U阀运行的因素众多，例如联通U阀供料室和排料室的孔口尺寸、物料颗粒的特征尺寸和密度、流化风、松动风和侧吹风等，然而现有研究只是针对单一影响因素进行分析，难以获得U阀运行规律的全貌，且实验研究不能从根本上理解U阀的运行规律。本文通过搭建循环流化床实验平台，研究了瓶颈道口控制排料、流态化排料和供料室控制排料状态下U阀的排料特性。主要结论如下：（1）瓶颈道口控制排料和流态化排料状态下，U阀排料量都出现先增大后恒定的趋势，前者达到最大排料量是因为瓶颈道口的限制，后者是因为供料室供料能力达到最大所致。（2）供料室控制排料的状态下，伴随松动风的增大U阀排料量增大，但是当松动风增大到一定值时，立管内物料由移动床转变为流化床，立管料柱料封作用被打破，U阀转变为流通阀，失去对颗粒物料排料量的调节作用。（3）通过比较瓶颈道口控制排料、流态化排料和供料室控制排料三种状态下的U阀排料可以看出，瓶颈道口控制排料时，U阀排料能力太小，而供料室控制排料时U阀排料调节范围小，且立管料柱料封作用容易被打破，因而流态化排料为U阀排料最佳状态。本文针对U阀流态化排料状态建立了以力平衡为基础的数学模型，用来计算排料速率等运行参数，得到的主要结论如下：（1）排料室压降随排料室表观气速增加而减小，而排料速率随排料室表观气速增加而增加。（2）排料室压降的计算值与实验数据相比，排料室压降平均计算误差为±2%。（3）排料速率的计算值与实验数据相比，排料速率平均计算误差为±7%。（4）计算结果与实验结果吻合较好，证明本数学模型可用于U阀流态化排料的设计与计算。
英文摘要	Circulating fluidized beds (CFB) are widely used in energy, resources and other fields. The returning system, consisting of a standpipe and a discharging valve, is the key component of CFB to achieve continuous operation. The U-valve is the most widely used discharging valve in industry because of its reliability, low pressure drop and easy adjustment. Many factors affect the operation of the U-valve such as the open size connecting the supply chamber and the discharging chamber, particle diameter, superficial gas veloity of the supply and the discharging chambers, which makes the modelling of the U-valve difficult due to the complex coupling among different parameters. It is therefore also hard to fully understand the characteristic of the U-valve only through experiments. In the present study a circulating fluidized bed with a U-valve was established and operated to study the performance of the U-valve, the discharge of the U-valve under bottleneck control mode, fluidization discharging mode and supply chamber control were investgated. The main conclusions are as follows. (1) The solid flow rate of the U-valve increases first with increasing superficial gas velocity and reaches a plateau when the superficial gas velocity exceeds certain value under the bottleneck control and fluidization discharging mode, which was caused by the limited open siez for the bottleneck control mode and by reaching powder supply limit of the supply chamber for the fluidization discharging mode. (2) When the discharging is controlled by the supply chamber, the solid flow rate of the U-valve increased with increasing the superficial gas velocity till the superficial gas velocity in the supply chamber reaches the minmium fluidization velocity, where the U-valve loses the seal capability and becomes a passby type valve. (3) The discharge ability of U-valve was too small under bottleneck control mode while the adjustment range was limited under the supply chamber control, so the best condition of U-valve was under fluidization discharging mode. A hydrodynamic model for the U-valve has been proposed based on the theory of Newton's second law to predict solid flow rate under the fluidization discharging mode. The calculated values were compared with those experimental data. The simulated pressure drop and solid flow rate are in good agreement with those experimental data, where the deviation was ±2% for the pressure drop across the discharging chamber, and ±7% for the solid flow rate, demonstrating the validity of the newly established model.
语种	中文
公开日期	2013-09-25
内容类型	学位论文
源URL	[http://ir.ipe.ac.cn/handle/122111/1790]
专题	过程工程研究所_研究所（批量导入）
推荐引用方式 GB/T 7714	彭莉. U阀流态化排料数学模型的建立[D]. 中国科学院研究生院. 2012.

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