负压差料斗中静态架拱机理实验研究

通过实验测量散体颗粒在负压差立管料斗中的静态拱宽度,验证本文模型的正确性,并分析了散体颗粒的无约束屈服强度、料斗形状、操作条件和延时效应对静态拱宽度的影响,提出负压差移动床立管料斗孔口最小直径的理论预测方法.     

负压差移动床立管料斗架拱实验研究

通过测量散体颗粒在负压差移动床立管料斗中静态拱宽度及分析散体性质、料斗形状和操作条件对料斗静态拱宽度的影响，得出当散体颗粒６４３．５ｋｇ／ｍ３≤ρｂ≤１０８５ｋｇ／ｍ３２６．７°≤θｒ≤３２．９°２２．４°≤δ≤３４．６°在负压差移动床立管的锥形料斗０°＜α≤２８．１°中形成静态拱时，其宽度可以通过下面的关联式求得：ＤｃａｌＤｓ＝０．２３８θｒδ０．１５８α－０．２７２（－ｄｐ／ｄｈ）ρｂｇ０．３８８     

负压差移移动床立管料斗架拱实验研究

通过测量散体颗粒在负压差移动床立管料斗中静态拱宽度及分析散体性质，料斗形状和操作条件对料斗静态拱宽度的影响，得出当散体颗粒６４３．５ｋｇ／ｍ＾３≤ρｂ≤１０８５ｋｇ／ｍ＾３ ２６．７°≤θｒ≤３２．９° ２２．４°≤δ≤３４．６°在负压差移动床立管的锥形料斗０°〈α≤２８．１°中形成静态时，其宽度可以通过下面的关联式坟得：（Ｄｃａｌ／Ｄｓ）＝０．２３８（θｒ／δ）＾０．１５８（α／Φ）＾－０．２７     

负压差立管中散体颗粒循环量突变对动态拱宽度的影响

以预测静态拱宽度模型为基础，结合立管中气固之间相互作用特征，推导出散体颗粒循环量突变对料斗中形成的动态拱宽度影响的理论模型．利用散体颗粒在无压差条件下通过孔口流落来模拟其循环量突变，实验证明模型可以预测立管中散体颗粒循环量突变时料斗中动态拱宽度，指出了今后工作的主要方向．     

漏斗-立管系统悬料区的压降计算方法

对于Ｇｅｌｄａｒｔ－Ｄ类颗粒在负压差漏斗－立管系统的悬料操作区的压降可以通过郭慕孙提出的气固移动床的公式求得。计算所得的压降大小与实验结果相比较误差在２０％的范围内;并且证明悬料区的总压降可以近似等于立管的压降。     

不同类型颗粒的振动流态化

在一种新型复合振动流化床中研究了不同振动参数（ｆ＝１０～６０ＨＺ），Ａ＝０．５５×１０（－３）～１．５×１０（－３）ｍ）及不同操作条件对Ｇｅｌｄａｒｔ分类中的Ａ、Ｂ和Ｄ类颗粒起始流化行为的影响。结果发现，振动的引入可以降低颗粒的起始流化速度，对于较细的颗粒降低幅度可达４５％左右；而对于较粗的颗粒，起始流化速度则降低幅度较小。另外，静床高度的增加将使振动效果减弱，使得起始流化速度下降幅度减小。在较宽的实验范围内，提出了振动条件下起始流化速度的经验关联式。     

单组分颗粒振动流化床的流体力学研究（2）——床层膨胀和起始流…

本文在振动流化床中研究床层膨胀和颗粒的起始流化速度，分别研究颗粒物性、振动特性（频率、振幅）和静止床层高度对它们的影响，根据不同的振动条件下Ｇｅｌｄａｒｔ’Ａ、Ｂ、Ｄ类１３种物料起始流化速度的实验结果，关联了实验条件下起始流化速度的计算式，此计算式对振动流化床的设计具有指导意义。     

单组分颗粒振动流化床的流体力学研究（2）──床层膨胀和起始流化速度

本文在振动流化床中研究床层膨胀和颗粒的起始流化速度,分别研究颗粒物性、振动特性（频率、振幅）和静止床层高度对它们的影响,根据不同的振动条件下Ｇｅｌｄａｒｔ’Ａ、Ｂ、Ｄ类１３种物料起始流化速度的实验结果,关联了实验条件下起始流化速度的计算式,此计算式对振动流化床的设计具有指导意义。     

负压差料斗中静态架拱现象

利用增湿ＦＣＣ催化剂的方法模拟粘性颗粒在负压差立管中形成的静态拱．分析了不同的漏斗半锥角、颗粒的流动函数、含水量和延时效应对拱宽度的影响，实验结果证明连续模型预测拱宽度比结构模型更准确．     

微细粉体振动流化床的流体力学行为研究

本文利用一种振动流化床装置实现了对Ｇｅｌｄａｒｔ２分类中Ｃ类粉体的正常流化，研究了不同振动参数对床膨胀，最小流化等流化行为的影响，提出了振动条件下最小流化速度的经验关联式。     

Effect of interparticle cohesive forces on the flow behaviour of powders

In a paper previously published in this journal [1], the author derived a theoretical model of the mechanical behaviour of cohesive powders which takes into account the forces acting at interparticle contacts. In particular, this theory considers the increase in the adhesive forces transmitted at interparticle contacts with increasing consolidation. An over-simplification inherent in the assumptions underlying the theory results, however, in incorrect predictions concerning the unconfined yield stress of a cohesive powder. In the present paper, this weakness in the previous theory is eliminated. Further development of the theory results in a graphic representation allowing immediate visualization of the basic theoretical parameters. Determination of the latter is possible directly, by means of shear tests on cohesive powders. The usefulness of this improved theory is demonstrated through the representation of unconfined yield stress characteristics of various powders.     

Flow Properties of Highly Dispersed Powders at Very Small Consolidation Stresses

With a modified standard ring shear tester yield loci of highly dispersed, dry powders were measured at preshear normal stresses down to 32 Pa and shear stresses down to 10 Pa. At small consolidation stresses stress, σ₁, (< 500 Pa) the values obtained for the unconfined yield strength, σ_c, are proportional to the consolidation stress, σ₁.     

水泥粉体流动行为及其与不同材质库壁粘附性研究

水泥粉体流动性与其储存、输送、给料、混合等操作密切相关.通过休止角、内摩擦角、粘聚力和无侧限抗压强度测试方法,研究了含水率对水泥粉体流动性的影响,对比了水泥粉体与砂浆、钢、涂料、防腐卷材四种壁面材料的壁摩擦角和附着力.结果表明:随着水泥粉体含水率增加,休止角、粘聚力和无侧限抗压强度增加,水泥粉体流动性变差.松散堆积水泥...     

被动围压下PBX的冲击动态力学性能

采用铝套筒和TATB基PBX,应用霍普金森压杆被动围压试验方法,研究了PBX在围压下的动态力学响应,得到了该PBX不同应变率下的屈服强度.结果表明,随着应变率的提高,屈服强度有所提高;围压状态下PBX承受的应力远高于无围压状态,变形从脆性向塑性转变,样品未发生明显的破坏.     

INVITED REVIEW: FLOW BEHAVIOUR OF COHESIVE MATERIALS

Many problems associated with solids handling originate in the influence of the cohesive forces on the flow behaviour of fine powders. Therefore first it is discussed why and under what conditions the property "cohesion" is of particular interest. The results of measurements relating the dependence of cohesive forces on previous compression are then reported. A theoretical model is derived which takes into account the forces acting in interparticle contacts. The theory especially considers the increase in the adhesion forces transmitted in interparticle contacts with increasing consolidation. Permitted simplification of the theory results in a graphic representation allowing immediate visualization of the basic theoretical parameters. Determination of the latter is possible directly, by means of shear tests on cohesive powders. The usefulness of the theory is demonstrated through the representation of unconfined yield stress characteristics of various powders.     

INVITED REVIEW: FLOW BEHAVIOUR OF COHESIVE MATERIALS

Many problems associated with solids handling originate in the influence of the cohesive forces on the flow behaviour of fine powders. Therefore first it is discussed why and under what conditions the property "cohesion" is of particular interest. The results of measurements relating the dependence of cohesive forces on previous compression are then reported. A theoretical model is derived which takes into account the forces acting in interparticle contacts. The theory especially considers the increase in the adhesion forces transmitted in interparticle contacts with increasing consolidation. Permitted simplification of the theory results in a graphic representation allowing immediate visualization of the basic theoretical parameters. Determination of the latter is possible directly, by means of shear tests on cohesive powders. The usefulness of the theory is demonstrated through the representation of unconfined yield stress characteristics of various powders.     

慢速热解对生物质粉体物性的影响

慢速热解方法可以有效地脱除生物质中的氧元素,提高生物质的能量密度,从而提高生物质气流床气化合成气的热值;并可以有效地改善生物质的物性,实现稳定连续的输送。使用直剪仪对不同粒径的生物质和不同热解温度的半焦进行物性分析,结果表明:热解后,半焦的休止角、内摩擦角和开放屈服强度都明显降低;堆积密度比原料的堆积密度大;从电镜图片分析得出表面结构的变化是物性发生变化的根本原因;400℃半焦的休止角为38.8°,堆积密度为269.4 kg/m3,开发屈服强度为26.8 kPa,并结合半焦气化合成气的热值得出400℃半焦作为气化原料比较合理。     

The influence of particle size distribution on the flow properties of limestone powders

The flow properties due to Jenike have been determined for several limestones powders of various particle size distributions. For cohesive powders, higher values for the unconfined yield strength, the effective angle of friction and the bulk porosity are attained than for free flowing powders. The particle size distributions by volume have been characterised by the average particle size, the variation coefficient and the skewness. Narrow particle size distributions were investigated in order to see the influence of the average particle size. Wide particle size distributions were studied to see the influence of the variation coefficient. The average particle size and the variation coefficient are suitable in making predictions of flowability.     

Characterization of powder flow: Static and dynamic testing

Many characterization techniques are available to determine the flow properties of powders; however, it is debated which method(s) are the most appropriate. In this study, sample fine powders with a medium particle size between 22 and 31 µm were characterized using a variety of techniques that tested powders under different stress states, ranging from static to dynamic. It was found that characterization techniques that were more dynamic such as fluidized bed expansion were best suited for predicting the fluidization performance while characterization techniques that were more static such as cohesion were better for predicting agglomeration. It was also found that results from static and dynamic characterization do not necessarily agree, where fine powders that showed good fluidization performance also displayed increased agglomeration, and vice versa. This suggests that flow properties are dependent upon the stress state and that no single technique is suitable for the full characterization of a powder. In other words, both static and dynamic characterization techniques must be employed to completely understand the flow properties of a powder and predict how it will behave under different process conditions.