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题名	隔板式生物质内循环流化床的流动特性研究; Experimental Study on Particle Flow Characteristics in a Claboard-type Internal Circulating Fluidized Bed Reactor
作者	黄立成
学位类别	硕士
答辩日期	2007-06-08
授予单位	中国科学院广州能源研究所
授予地点	广州能源研究所
导师	马隆龙
关键词	内循环流化床 流动特性 生物质气化
其他题名	Experimental Study on Particle Flow Characteristics in a Claboard-type Internal Circulating Fluidized Bed Reactor
中文摘要	The fluidized bed, as an efficient and high production capacity reactor, has desirable characteristics on biomass gasification. However, some factors lead to its low gasification efficiency, including: the fly ash from the circulating fluidized bed gasifier containe too much carbon; the residence time of biomass carbon in the furnace is relatively short and it is difficult to make the ash circulating. A new Clapboard-type Internal Circulating Fluidized Bed (ICFB) was designed to solve these problems. The fluidized bed was divided into fast bed and slow bed by a clapboard set vertically. The internal circulating fluidization of particles around the clapboard was realized. The slow bed was mainly gasification area, and the fast bed is mainly chark combustion area. A cold-state test was performed on a small-scale clapboard-type internal circulating fluidized bed gasifier for three kinds of bed materials, namely rice husk, quartz sand and sawdust. The effects of gas velocities, structural parameters and the amount of side air on the solid circulation rate were investigated. Besides, the mixed characteristics and internal circulating fluidization characteristics for mixture of rice husk、quartz sand and mixture of sawdust、quartz sand were studied in the clapboard-type internal circulating fluidized bed. The fluidization hydrodynamics of pure biomass particles and quartz sand was investigated, the experimental results showed: (1) because of the low density of rice husk and sawdust, it was hard to form good fluidization, channel and slugging could be observed in the slow bed, which made the fluidization worse. The operation gas velocity to obtain stable and fine internal circulation in the fluidized bed must satisfy conditions as follows: for rice husk, uL/umf>1.4，uH/umf>1.7；for quartz sand, uL/umf>1.0，uH/umf>1.9；for sawdust, uL/umf>1.2，uH/umf>2.1. (2) The solid circulation rate would be dramatically influenced by the gas velocities of two beds. When other conditions were kept constant, with the increasing of gas velocities of fast bed, the solid circulation rate and the pressure drops across the orifice increased first and then decreased, and there exited a maximum value which emerge at：for rice husk, uL/umf>1.4，uH/umf=2.2～2.4；for quartz sand, uL/umf>1.0，uH/umf=3.5～4.5；for sawdust, uL/umf>1.2，uH/umf=3.0～4.0. (3) The height of clapboard and the size of orifice also had great influence on the solid circulation rate. The circulation rate of solids first increased then decreased with increasing height of clapboard. The clapboard height should be nearly equal to the initial static bed height to obtain high solid circulation rate. The circulation rate of solids increased sharply first and then slowly with increasing the orifice height. The reasonable operation and design parameters were put forward to obtain high solid circulation rate: the height of orifice was between 0.12～0.2Hmf；the height of clapboard was between 0.9～1.2Hmf. (4) The side air could effectively improve the fluidization quality in slow bed. The solid circulation rate of solids increased sharply first and then slowly with increasing the amount of side air. (5) The correlation formulas to calculate the particle flow rate through the orifice for quartz sand、rice husk and sawdust were set up. The relative error between calculation results and experimental data were less than 6%、14% and 46% for quartz sand、rice husk and sawdust respectively. Quartz sand belongs to type-B particles which have desirable fluidization characteristics, and rice husk belongs to type-D particls, for these particles the empirical equation has showed good prediction ability. But for sawdust which is particle with low density and small average diameter, other more suitable empirical equation is required to achieve good prediction. Finally, the mixed characteristics and internal circulating fluidization characteristics for mixture of rice husk、quartz sand and mixture of sawdust、quartz sand were studied in the clapboard-type internal circulating fluidized bed. The results showed: (1) Due to the wrapping and covering of quartz sand, the mixture of biomass particle and quartz sand could form uniform mixing and stable internal circulating flow in the clapboard-type internal circulating fluidized bed. The operation gas velocity to obtain stable and fine internal circulation in the fluidized bed must satisfy conditions as follows: for the mixture of rice husk and quartz sand, uL/umf>1.2, uH/umf>2.0; for the mixture of sawdust and quartz sand, uL/umf>1.3, uH/umf>1.8. (2) The solid circulation rates of the two mixtures increased first then kept constant with increasing gas velocity of fast bed, which is similar to the trend of pressure drop across orifice. The addition of quartz sand could expand the operating specification of high solid circulation rate, and improve the internal circulating fluidization characteristics. The flow resisting force of the mixture is smaller and more stable than that of pure biomass particles.
语种	中文
公开日期	2011-07-10 ; 2011-07-15
页码	71
内容类型	学位论文
源URL	[http://ir.giec.ac.cn/handle/344007/4019]
专题	中国科学院广州能源研究所
推荐引用方式 GB/T 7714	黄立成. 隔板式生物质内循环流化床的流动特性研究, Experimental Study on Particle Flow Characteristics in a Claboard-type Internal Circulating Fluidized Bed Reactor[D]. 广州能源研究所. 中国科学院广州能源研究所. 2007.

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