固体颗粒对固液搅拌槽中局部液相速度的影响

分别以粒径不同的树脂和玻璃珠为固相,以水为液相,采用双电导电极探头考察了固体颗粒粒径、固体颗粒浓度和颗粒密度对搅拌槽内固液悬浮体系的局部液相速度的影响.结果表明,加入不同密度和粒径的固体颗粒后,局部液相速度随着固体颗粒直径、固体颗粒体积浓度和密度的增大而减小;固体颗粒直径和密度对剪切速率和循环流量的影响不显著.     

啮合型同向旋转双螺杆挤塑螺槽非充满的固体输送的理论研究

本文依据作者建立的啮合型同向旋转双螺杆挤出非充满固体输送的理论模型，以区域型和边界型相结合的数值计算方法，对非充满螺槽的非塞流固体输送的应力场和程度场进行了求解，并了讨论子其影响因素。     

固液搅拌槽内液相速度的分布

在两个几何相似固 -液搅拌槽内 ,采用双电导探针测定了固体浓度较高的固液体系中液相速度的分布 .固相质量分数从 12 .5 %至 38.2 % (体积分数C_v 从 5 .4 %至 19.8% ) ,搅拌槽直径分别为Ф80 0mm与Ф16 0 0mm ,采用一种高效的长薄叶螺旋桨搅拌器 (CBY)向下泵送操作 .实验研究了固体浓度变化以及搅拌槽放大对液相速度分布的影响 .根据所测速度分布计算了不同直径槽内悬浮液中叶轮的流量准数.     

啮合型同向旋转双螺杆挤塑螺槽非充满的固体输送的理论研究(Ⅱ) 应力场和速度场的求解

本文依据作者建立的啮合型同向旋转双螺杆挤出非充满固体输送的理论模型,以区域型和边界型相结合的数值计算方法,对非充满螺槽的非塞流固体输送的应力场和速度场进行了求解,并讨论了其影响因素。     

密相气力输送水泥粉体流动特性研究

论文建立了工业级别1∶1正压旋转供料器气力输送实验系统。在本实验系统上以两种不同水泥粉体为输送物料进行气力输送研究,通过改变输送管道内的气体速度得出了固体输送能力、平均固气质量比、固体平均速度及单位长度压力损失等参数的变化规律,为该类型气力输送水泥粉体提供依据。     

专利技术

<正>一种制备氯化钾的方法本发明公布了一种制备氯化钾产品的新方法,具体步骤:1)以有较高含量氯化钾、氯化镁和氯化钠的光卤石盐为主的盐水为原料,经多级蒸发、浓缩除去卤水,分别得到第一固体和第一液体,第一固体主要含氯化钠,可优选通过离心或过滤分离除去;2)采用冷却水直接冷却,或者用盐水溶液、乙二醇溶液等冷却第一液体并按步骤(1)将其分离,得到第二固体和第二液体,第二固体中主要含氯化钾、氯化镁和氯化钠;3)富集并按步骤(1)分离除去第二固体,得到第三固体     

光信号互相关法测量循环流化床内颗粒速度的应用研究

光信号互相关方法被广泛地应用于流化床中固体颗粒速度测量.基于互相关原理,本文讨论了各种因素对计算结果的影响,详细地叙述了光纤信号的处理过程.计算窗口重叠法得到的颗粒速度能更详尽地反映固体颗粒的动态变化,而采用的中位数法确定的时均速度具有较强的数值稳定性.计算结果能够较好地反映循环流化床颗粒速度的径向分布特点,为循环流化床颗粒速度的测量提供可靠的数据.     

喜树碱-七元瓜环包合物的制备及溶解性的考察

采用共蒸发法制备了喜树碱一七元瓜环固体包合物,x-射线粉末衍射及红外光谱证实喜树碱与七元瓜环形成了固体包合物。通过紫外分光光度法考察了包合物的包合率、溶解度和溶出速度。包合物的产率和包合率都达到了80％以上,包合物能使药物的溶解度提高了近70倍,在pH=1．00介质中10min内药物即可达到100％的溶出。     

一种增加粗盐溶解速度的新方法

化盐工段是氯碱工业生产中的第一个工段,它是将原盐与蒸发工段送来的回收盐水、盐泥和回收的淡盐水按比例掺和,溶解成氯化钠的饱和水溶液,同时将溶液中的杂质除去的工段。化盐桶是化盐工段的一个重要设备,它的作用就是将固体原盐和其它回收的     

燃速测试中导电现象的研究及解决方法

叙述了含高氯酸铵、铝粉的固体推进剂,在线性恒压燃速测试过程中,出现的导电现象,往往使测试失败。在研究其导电原理后,采用了在记时系统中,适当改变连结第一靶、第二靶的电阻值,可使燃速测试成功率在90%以上。     

Application of high-speed centrifugation to studies of plastic spreads

Summary By means of the analytical ultracentrifuge the rate of separation of a plastic spread into liquid and solids phases was observed and the proportions of each phase determined. An estimate of the amount of true solids was complicated by the fact that the solids phase consisted of approximately one-half oil. In the preparative ultracentrifuge sufficient quantities of the oil phase were isolated for chemical analysis. Centrifugation at each of several temperatures and analysis of the oil and solids phases would yield a characterization of the different components which crystallize at various temperatures. By centrifuging the plastic spread with a layer of aqueous alcohol of density intermediate to the oil and solids, the solids phase was separated more nearly oil-free. The solids phase however still was not sufficiently pure to permit a chemical characterization representative of the solid component. Corrections can be made however for the effect of occluded oil. Presented at the American Oil Chemists' Society Meeting, New Orleans, La., May 4–6, 1953. One of the Branches of the Agricultural Research Service, U. S. Department of Agriculture.     

Effect of oil viscosity on the rheology of oil-in-water emulsions with added solids

This paper reports an experimental study on the effect of oil viscosity on the rheology of oil-in-water (o/w) emulsions with added solids. Four oils having a viscosity range of 0.0024 to 306 Pa . s were used. The size ratio of the solids to oil droplets was varied from 2 to 16. The addition of smaller size solids to the emulsions yielded a higher viscosity than that of larger solids at the same solids volume fraction. However, when the solids were sufficiently large such that the emulsions behaved as a continuous phase towards the solids, the viscosity of the emulsion-solids mixtures tended to be independent of the solids size. The critical size ratio of the solids to oil droplets, above which the emulsions behaved as a continuous phase towards the solids, increased with the oil viscosity. The critical size ratio varied between 3 and 10.     

大型循环流化床流动结构分析

采用双光路光纤密度探头和激光多普勒测速仪测量了内径418mm,高18m的大型循环流化床提升管和下行床中的瞬态颗粒浓度信号和颗粒速度信号.对瞬态颗粒浓度和颗粒速度的概率密度分布分析表明,下行床中存在着和提升管中不同的微观流动结构,在提升管内流动结构存在明显的两相：即颗粒团相和空穴相,两相的固含率分别为接近1-ε_mf和0.01～0.02.而在下行床中,虽然在边壁也存在着颗粒的团聚行为,但不能形成稳定的、固含接近于起始流化状态固含值的颗粒团相.这种流动结构的区别揭示了下行床中气固顺重力场运动和提升管逆重力场运动在流动机制上的差异.     

Characterization of dilute and dense phase vertical upflow gas-solid transport based on average concentration and velocity data

Dilute, ‘dense phase 1’, and possibly a third regime-‘dense phase 2’, were observed in a vertical 0.02 m diameter pneumatic conveyor using 210 μm sand particles. The transitions were marked by the alterations in the trend of the measured average solids hold-up while varying the solids mass flowrate at constant air velocity. Hydrodynamic characteristics together with the transition criteria for the various transport modes were established. A novel regime diagram based on average gas velocities and solids mass flowrates was developed to identify the operating conditions for these regimes, as well as the limiting solids carrying capacities of the present conveyor. A probable cause of the dilute to dense phase transition is speculated upon.     

Flow patterns in high-velocity fluidized beds and pneumatic conveying

Four flow patterns are identified for gas-solids vertical upward flows. Homogeneous dilute phase flow is characterized by the absence of both radial and axial solids segregation. Heterogeneous dilute phase flow (also called core-annulus flow) is characterized by the absence of axial solids segregation, with solids carried upward in the core and travelling downward near the outer wall due to the formation of particle streamers. Collapsed flow with a lower dense region and an upper dilute region is also referred to as the fast fluidization regime. In this case, the flow structure in the upper dilute region is similar to that in heterogeneous dilute phase flow, while the lower dense region resembles that in a turbulent fluidized bed. Dense phase flow can be reached when the riser is completely occupied by a relatively dense suspension with little axial density variation and no net solids downflow near the riser wall. The transition from fast fluidization to dense phase flow is still not clearly defined.     

Hydrodynamics of an annulus airlift reactor

The hydrodynamics of an annulus airlift reactor (AALR) was studied and compared with that of a slurry bubble column reactor (SBCR) with silica sands of 75-125 μm in size as solids, city tapping water as liquid phase, and air as gas phase in the present investigation. The effects of superficial gas velocity and solids concentration on gas holdup and solids distributions were investigated. The results showed that the local average gas holdup decreased along the column height, and the average gas holdup decreased with the increasing solids concentration, but this tendency became less at higher solids concentrations. It was found that the effect of superficial gas velocity on axial solids distribution was negligible over the gas velocity range investigated, as long as the solids in the column could be suspended. Increasing solids concentration led to flatter axial solids holdup profiles. The axial distributions of solids concentration and gas holdup in the AALR were much more uniform than those in the SBCR, and slurry circulation in the AALR damped the effects of increasing solids concentration on the hydrodynamics. These advantages of an AALR over a SBCR are especially important for some catalytic reaction processes in three-phase systems such as Fischer-Tropsch synthesis and methanol synthesis.     

Phase distributions in a gas–liquid–solid circulating fluidized bed riser

The distributions of the three phases in gas–liquid–solid circulating fluidized beds (GLSCFB) were studied using a novel measurement technique that combines electrical resistance tomography (ERT) and optical fibre probe. The introduction of gas into a liquid–solid circulating fluidized bed (LSCFB), thus forming a GLSCFB, caused the increase of solids holdup due to the significantly decreased available buoyancy with the lower density of the gas, even with a somewhat increased liquid velocity due to the decreased liquid holdup giving space for the gas holdup. The gas passed through the riser in the form of bubbles, which tended to flow more through the central region of the riser, leading to more radial non‐uniformity in radial holdup of the phases. The gas velocity has the most significant effect on the gas phase holdup. While the gas velocity also has an obvious effect to the solids holdups, the liquid flow rate had a much more considerable effect on the phase holdups. The solids circulation rate also had a significant effect on the phase holdups, with increasing solids circulation rate causing much more increased solids holdup in the central region than close to the wall. A correlation was developed for the relative radial distributions of solids holdup in GLSCFB, as such radial profiles were found similar over a wide range of operating conditions, like those in a typical gas–solid circulating fluidized beds (GSCFB). Finally, the axial solids profiles in a GLSCFB was found to be much closer to those in an LSCFB which are very uniform, than those found in a GSCFB which are less uniform and sometime having a S shape. Water was used as the continuous and conductive phase, air was the gas phase and glass bead and lava rock particles were used as the solid and non‐conductive phase.     

液固环管反应器中液固两相轴向扩散特性的研究

液固环管反应器中液固两相轴向扩散特性的研究梁五更，俞芷青，金涌，汪展文，陈靖（清华大学化学工程系，北京１０００８４）关键词：环管反应器，液固系统，轴向扩散１前言混合特征是反应器的基本流体力学性质。有关环管反应器的混合行为已有一些研究，但都集中于气－液...     

石油焦燃烧器环流混合段内床层的轴向密度分布

采用气-固环流反应器与输送床烧焦管相结合的结构形式,建立了一套适应石油焦或气化余焦燃烧要求的大型冷态实验装置. 在不同操作条件下,采用差压变送器测定了环流混合段内环区及外环区内床层轴向压力梯度及密度的分布规律. 结果表明,内环床层密度分布可分为底部密相区和上部湍流扩散区;内环颗粒循环强度对底部密相区的密度分布影响较小,只对导流筒上部湍流扩散区有影响;随着内环表观气速的增大,整个内环床层密度均降低. 外环床层密度分布与内环的表观气速、颗粒循环强度和外环床层密相料位高度有关. 利用实验数据回归出了内环和外环轴向颗粒密度分布的经验模型,其计算值与实验值吻合较好.     

连续内环流三相反应器局部流动特性

在φ200 mm×2500 mm连续内环流三相反应器内，考察了空气 水 玻璃珠体系反应器内局部流动参数随操作条件的变化规律。结果表明，导流筒内截面平均气含率随表观气速的增大而增大，较之气液两相流，在低固含率时，加入固体对气含率影响不明显，而在较高固含率下，气含率有明显降低，但固体再增加时对气含率变化影响不大。在较低表观气速下，进料浆速对导流筒内气含率轴向分布趋势有一定的影响，但在较高表观气速下影响不大，导流筒内的气含率大于环隙内的气含率且随气速增大差别更加明显，浆相连续有利于气相分散并增大环隙内的气含率。导流筒内循环浆速径向分布呈抛物状，中心高、近壁处低，受进料浆速和入口固含率影响都不大。浆相循环强度最低为20，高可达180。固含率轴、径向分布受表观气速和进料浆速的影响，固含率轴、径向分布基本均匀，随进料浆速增加，反应器内固含率降低。