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复合生物流化床流动特性研究 总被引:2,自引:1,他引:2
本文对具有导流简流化床与填料固定床相结合的复合生物流化床的床层流体力学特性、混合特性及传质特性进行了研究。复合床的流型可分为 PPBM,PFBM,PCBM,其中 PCBM 最适于流化操作,通过对不同固体颗粒的实验,对床层压降及摩擦因数、床层平均气含率、气泡下潜深度、液体的循环速率、床层混合特性及气-液传质系数进行了讨论和关联,并得出了相应的计算模型。 相似文献
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<正> 一、概 述 流化床反应器是化工部门常用的一种反应器,由于有许多优点而得到广泛使用。近年来,它作为干燥设备在化工,轻工和食品加工业中得到了广泛的使用。此外,它作为燃烧设备的流化床锅炉已成为锅炉的一个新的分支,并得到迅速发展。流化床反应器通常是在高温下或高于环境温度的状态下工作。流化床的床层温度(简称床温T_b)不同时,床层流动特性不同。这个问题以前没有引起足 相似文献
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分析了两种窄筛分D类颗粒在不同喷动-流化操作条件下的床层行为特征及床层总气流阻力,研究了平底型三维喷动-流化床内的气体流动模式,从而导出在固定床阶段床层总气流阻力的表达式,得出喷动-流化操作具有优越性的结论。 相似文献
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介绍了一种基于循环流化床的动力系统方案——循环流化床置换燃烧。这种燃烧系统能在没有能量损失的前提下,将CO2从燃烧产物中分离出来。本文设计建立了一套燃煤循环流化床置换燃烧冷态实验系统,以此为研究对象,选择具有代表性的实验物料,利用测试系统取得多种信号参数,获得反应装置之间的气固流动特性,总结出一定的规律,为以后的热态实验以及进一步探索奠定基础。 相似文献
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介绍了一种基于循环流化床的动力系统方案———循环流化床置换燃烧。这种燃烧系统能在没有能量损失的前提下,将CO2从燃烧产物中分离出来。本文设计建立了一套燃煤循环流化床置换燃烧冷态实验系统,以此为研究对象,选择具有代表性的实验物料,利用测试系统取得多种信号参数,获得反应装置之间的气固流动特性,总结出一定的规律,为以后的热态实验以及进一步探索奠定基础。 相似文献
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在含内置过滤器的三相流化床装置中,以空气、水、沙子三相为研究介质,对其过滤特性进行研究,考察了操作条件对过滤通量、反吹时间间隔、临界液速、最大液速的影响.结果表明:气速越大过滤通量越大;反吹时间间隔随液速增大明显减小,随气速增大而减小的慢;临界液速随气速增加而增大;最大液速随气速的增大而减小. 相似文献
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FCC细颗粒湍流流化床流体力学性能研究李俊,张蕴璧,闫遂宁(西安石油学院,西安710061)(西北大学)(洛阳石化公司)关键词:流化床,湍流,气泡,空隙率1前言湍流流化床有着广泛的工业背景。湍流流化床反应器存在着物质空间分布的不均匀现象,这种分布对湍... 相似文献
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In a liquid-solid fluidized bed, the apparently irregular or stochastic behavior of particles gives rise to various flow regimes depending on parameters such as the particle size, liquid flow rate, static bed height and axial position in the bed. It is highly plausible that this irregular behavior manifests itself as pressure fluctuations; thus, the effects of these parameters on the particle behavior or the particle flow regime were investigated through measurement and spectral analysis of the pressure fluctuations. The results indicate that the amplitude of pressure fluctuations exhibits a maximum and that the decay constant in the autocorrelation function attains its minimum at the intermediate liquid flow rate where the particle flow regime undergoes transition from the cluster circulation to the individual quasi random motion. The model composed of the periodic and stochastic components of pressure fluctuations, is in good accord with the experimental results in terms of both the autocorrelation and power spectral density functions. 相似文献
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论述了快速床区流体动力学的结构,研究了快速床区纵向和横向悬浮密度分布的规律及相应的计算公式。对影响快速床区动力学结构的主要因素,如固体颗粒的循环率、气体速度等进行了试验研究,对循环流化床锅炉的设计和运行有一定的指导意义。 相似文献
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研究了粗颗粒树脂加压流态化时气固混和物自由出料过程的物理模型,建立了出料气含率与流化床结构参数、操作条件之间的关系。计算表明出料气含率的理论预测值和测量值一致。运用此结论进一步计算了流化床乙烯聚合反应生产聚乙烯工业过程中乙烯的原料单耗值,为工业生产指标的分析计算提供了理论依据 相似文献
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Heat transfer coefficients were measured for 227 and 87 micron size particles of silica sand in a 102 mm dia. and 5.5 m tall circulating fluidized bed made of plexiglass. Effects of solid circulation rate, fluidization velocity, bed density and particle sizes were studied. The heat transfer coefficients were calculated from the temperatures measured along the axis of a 25 mm dia 100 mm long cylindrical heat flux meter. 相似文献
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Experiments were carried out to determine the gas-solid mass transfer coefficient for the air-naphthalene system under fast-fluidized conditions. The data were obtained under conditions of high voidage (as high as 98%) and high gas velocities (0·5 m/s-2·2 m/s). The results indicate that the correlation for the mass-transfer coefficient in a gas-solid fluidized bed under low voidage conditions established by previous investigators can be extended to the fast fluidization regime. Significantly lower mass transfer coefficients were, however, obtained under high voidage compared to low voidage conditions. 相似文献
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S. Heinrich M. Ihlow M. Henneberg M. Peglow E. Machnow Lothar M rl 《Drying Technology》2002,20(1):175-194
In general, drying processes are described by the quantity of air humidity of the exiting gases. This approach is not possible however by the drying medium of water in steam drying, since the air humidity naturally possesses a constant value of 100%. This paper presents a model which represents the drying processes on the basis of the observation of temperature profiles of the material and energetic balancing of all components involved as well as the wall of the apparatus. The modeling differentiates three intervals: the condensation phase, the 1st drying period and the 2nd drying period. In addition, a validation of the model on the basis of experiments in an experimental plant DN100 belonging to the university is dealt with. The satisfying concurrence of the theoretical and practical results shows that, with the help of the theoretical model, discontinuous steam drying processes can be theoretically described with sufficient accuracy. 相似文献
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Prabir Basu 《Chemical Engineering Communications》1985,39(1):297-308
The local void around a sphere in a packed bed or in the emulsion phase of a fluidized bed has been calculated theoretically; and measured as a function of the radial distance from the centre of the sphere. Effects of this distribution on the burning rate and Sherwood number have been investigated for two types of bed e.g. where inerts are of the same size as the carbon particle and where the inerts are smaller than the carbon particle. Even though the present analysis studies the effect on the diffusive component of the mass transfer alone, the results suggest that the distribution of voidage will yield Sherwood numbers higher than that calculated from the constant voidage assumption. The voidage distribution explains the increase in burning rate of carbon with increasing size of the inerts. 相似文献