充气水力雄流器内矿化气泡运动行为的研究

本文对充气水力旋流器内的矿化气泡（特指矿粒与气泡聚合体的总称）从形成处到进入泡沫柱区这一过程行为进行了全面的研究，采用快速摄像分析法测定了气泡的运动行为，从压力梯度的角度着手研究了矿化气泡运动过程中的推动力，还从理论上探讨了矿粒大小及离心力强度对矿化气泡运动行为的影响等。本研究结果使用充气水力旋流器内矿化气泡的运动行为得到了较为系统的描述，从而为揭示充气水力旋流器内的分选过程行为作出了重要贡献。     

充气水力旋流器内矿化气泡运行行为的研究

本文对充气水力旋流器内的矿化气泡（特指矿粒与气泡聚合体的总体）从形成处到进入泡沫柱区这一过程行为进行了全面的研究，采用快速摄像分析法测定了气泡的运动行为，从压力梯度的角度着手研究了矿化气泡运动过程中的推动力，还从理论上探讨了矿粒大小及离心力强度对矿化气泡运动行为的影响等，本研究结果使用充气水力旋流器内矿化气泡的运动行为得到了较为系统的描述，从而为揭示充气水力旋流器内的分选过程行为作出了重要贡献。     

螺旋构件强化排液的泡沫分离塔用于牛血清蛋白分离

引言 泡沫分离技术又称泡沫吸附分离技术[1],是以气泡作为分离介质,利用被分离组分在气液两相界面吸附性质的差异进行浓缩溶液中表面活性组分.在泡沫分离过程中,通过空气分布器在泡沫塔液相中产生气泡,气泡沿着轴向向上流动,被分离表面活性组分吸附在气泡的气液两相界面上,当吸附接近平衡后,气泡离开液相,在液相上方形成泡沫相.     

光电毛细管探头法测量搅拌槽中气泡大小分布的研究

本文以提供搅拌槽中气泡大小分布的测定方法为目的,对用光电毛细管探头法测量气泡大小分布过程中存在的关键问题:如何由毛细管内光电检测处的气泡长度正确地反映出搅拌槽中取样微元内的气泡大小分布,提出了较为合适的解决方法,具体包括:(1)保证进入取样微元内的大小气泡全被抽进毛细管;(2)避免气泡在毛细管的喇叭口内合并;(3)准确计算毛细管内轴向流体压力分布和气泡周围的液膜厚度。     

喷射环流三相流化床反应器轴向液速分布的研究

在喷射环流三相流化床反应器中，应用本文所开发的内热式热膜流体速率探头，获得了带有沉降分离区的夹套式环流反应器在不同压力、气量、流量条件下，不同轴向位置的液体速率分布规律。对于本文所述这类反应器，喷射区流体运动速率最大；自喷口向上，速率先是随距离的增大易急骤下降，然后逐渐向一渐近点逼近；当进入环隙转折口处时，由于气体的逸出及流道的变化液速急骤下降；凝固相进入环隙时，液速随距离的变化也存在渐近点。当采用变径结构时，流道面积突变处的液速变化率仅次于喷射入口区。在环流反应器中，液速主要取决于喷射动能及气提推动力，受液体进料量及压力的影响较小。     

气液外环流反应器中气泡行为的实验研究

详细考察了气液外环流反应器中上升管、下降管的气泡行为随轴向、径向的变化规律. 由于外环流反应器的结构特点,发现在上升管底部存在偏流,并对分布板区气泡行为随角向的变化规律进行了研究. 分析实验结果得出,气含率和气泡速度均随表观气速的升高而升高;在上升管内,气含率和气泡速度自中心向边壁逐渐降低,而沿轴向变化很小;在分布板区,由于受分布器及下降管的影响,使气含率和气泡速度在不同角向存在不同的径向分布. 在下降管中,气含率自中心向边壁逐渐降低,而气泡速度则基本不变;且下降管中的气体循环率随表观气速的升高而升高.     

气-固环流反应器内瞬态流体力学特性的数值模拟

采用双流体模型和颗粒动力学理论,并考虑颗粒团聚现象对气固相间曳力的影响,对气-固环流反应器内的流体力学特性进行了数值模拟。模拟的时均固含率和颗粒速度与实验数据具有较好一致性,验证了模拟方法的可靠性。模拟结果表明：气-固环流反应器内瞬态固含率的分布具有典型聚式流态化的非均匀特征;压力脉动沿床层轴向的分布在一定程度上定性反映了气泡运动的信息;颗粒速度的时间序列和概率密度分布函数表明,床层各径向位置均存在颗粒的向上、向下运动,颗粒主体在床层内向上运动的同时还存在微观的内循环运动,模拟值为颗粒时均速度的径向非均一性宏观分布提供了合理的微观解释。     

分布器对鼓泡塔中气泡直径分布的影响

采用电导探针测定了冷态鼓泡塔中不同气速下的气泡直径及气含率的轴向分布,考察了分布板对鼓泡塔操作性能的影响.结果表明:随着开孔率的减小,从均匀鼓泡区到过渡区的转变提前;在均匀鼓泡区,开孔率对气泡直径影响较小;在过渡区,开孔率大的分布器形成的稳定气泡直径较小、气含率较大;分布板开孔直径越大,形成的初始气泡直径越大,但对轴向气泡直径分布的影响仅限于分布器区.包含分布器影响的气泡直径经验关联式为d/D=140.2Bo-0.5Ga-0.12Fr0.099(h/D)-0.15T-0.34(0.5 cm/s＜ug＜7 cm/s).     

加压二维鼓泡床气固流动特性的数值模拟

采用欧拉双流体模型模拟了加压下二维鼓泡床内的气固流动特性,结果表明:在相同的表观气速下,加压使气泡体积分数增大,气泡相与乳化相间的分解越发明显,气固两相流动、混合剧烈;同时,床层中上部颗粒轴向速度的径向分布不均匀性增强:中心区颗粒速度增加,近壁区下降;随着操作压力变大,流化床膨胀高度增大,相应地,整体气含率增大,床层下部的颗粒浓度减小,而上部颗粒浓度增加,固含率在轴向上的分布更均匀;床层压力波动主要由两种成分构成:低频率高幅值和低幅值高频率成分.压力脉动强度随床高的增加呈现先增大后迅速减小的趋势;此外,加压下床层压力脉动强度变大,即床压波动更加剧烈;而且加压下颗粒拟温度增大,即颗粒速度脉动增强.     

排气管对旋风分离器轴向速度分布形态影响的数值模拟

采用数值模拟考察了排气管直径及结构对旋风分离器内轴向速度分布形态的影响。结果表明,改变排气管直径可使旋风分离器内轴向速度径向分布出现倒V形和M形两种不同的形态。排气管直径由小到大,轴向速度径向分布逐渐由倒V形转变为M形,轴向速度滞流最先产生于排气管内并不断向分离器下部空间扩展,排气管直径大到一定程度,轴向速度滞流甚至扩展至整个分离器空间。滞流区的径向范围亦随排气管直径的增大而增大;同时分离器中心轴向速度不断减小,滞流程度增加,甚至出现倒流。排气管下端扩口或缩口均可影响轴向速度的分布形态。上述轴向速度的分布形态与压力的轴向梯度相关,当排气管内能耗在总能耗中所占比例较小时,分离器中心压力的轴向梯度为正,从而使轴向速度产生滞流。     

A preliminary study of interfacial areas in vertical cocurrent,two-phase upflow

Pseudo-first order chemical absorption was used as the basis for determining the effective interfacial area available for mass transfer in gas-liquid, cocurrent, upward pipe flow. The study, which was performed in a 2.54 cm I.D. tube, encompassed the slug and froth flow regimes. The interfacial area displayed a strong dependence upon the coordinates of the flow regime map proposed by Oshinowo and Charles⁽¹⁶⁾. In addition, the systematic variation of surface area could be rationalized on the basis of flow regime geometry. Unfortunately the data could not be used to assess previous surface area models due to the unresolved diameter dependence of these models. Observations are also made concerning the apparently significant effect of chemical composition on interfacial surface area, and concerning the inadequacy of the popular methods used for estimating frictional pressure drop in vertical two-phase flows.     

Macro-pore structure characteristics of a low-rank coal and its froth flotation fractions

A high pressure Mercury Porosimeter (M.P.) (max. oper. press: 2000 atm) and an optical microscope interfaced with a Quantimct image analyser were employed to investigate the internal macro-pore structure of froth flotation concentrates of low-rank coal. The objective of the froth flotation process is to produce a demineralized product from a pulverized low-rank feed coal suitable for use in industrial combustors as the solid component of a coal-oil mixture (COM). The effectiveness of the coal for this use is associated with a rapid rate of combustion for which a knowledge of macro-pore distribution is useful. It is also of interest to know whether the pore-size distribution of the treated coal influences in any way the froth flotation process, possibly leading to selective separation based on internal pore structure. The experimental distributions showed a bimodal configuration with maxima located at pore sizes of ≈ 10 and ≈ 5500 nm. Overall specific surface areas ranging between 3.50 and 11.80 m²/g_c are substantially higher in comparison with results from literature obtained by M.P. and N₂ adsorption at ?196 °C. M.P. hysteresis results are discussed and a low mercury entrapment of ≈ 5% of the ultimate detected porosity was observed on froth flotation tailings with an ash content approaching ≈ 77%.     

板式塔降液管的机械消泡研究

研究开发了板式塔降液管机械消泡板组件。在降液管中加设特制的新型消泡板组件,该组件由数列若干块相互平行的倒V字形波纹板垂直排列组成,倒V字形波纹板的开口端向下。消泡板组件半浸于降液管泡沫层中,越堰的泡沫液与波纹板碰撞,以及波动的泡沫层不停地与波纹板摩擦,都加速泡沫的破裂,促进降液管内气液分离,降低了泡沫层高度。开口端向下的倒V字形波纹板还对降液管内液体产生向下的作用力,降低了降液管清液层高度。试验结果表明,对易起泡物系,降液管机械消泡板组件能降低泡沫层高度13.1%—36.2%,降低清液层高度10.5%—32.5%。对不易起泡物系,消泡板组件能降低泡沫层高度7.1%—33.2%,降低清液层高度5.1%—24.6%。因此,该消泡板组件可以起到降低降液管液层高度和延缓降液管液泛的作用,具有良好的消泡效果。     

Is subcooling the right driving force for testing low-dosage hydrate inhibitors?

The degree of subcooling is usually used as the driving force for hydrate formation; however, it does not encompass the effect of pressure. A comprehensive driving force for hydrate formation is a function of pressure, temperature, and gas composition; however, its calculation is not as simple as that of subcooling. In this work, by application of the two latest driving force expressions for hydrate formation, the relationships between subcooling and the true driving force at different conditions for pure gas-water and natural gas-water systems are analysed. The effect of pressure on the induction time in the presence and absence of a kinetic inhibitor have been tested at similar degrees of subcooling.The results show that for pure gas-water systems subcooling is proportional to the driving force, with a good approximation over a wide pressure range at isothermal conditions. However, for multicomponent systems (e.g., natural gases), the driving force is more than that suggested by subcooling at some pressures. Changes of driving force with pressure at a constant degree of subcooling for the above systems have been presented. The results show that the pressure has no significant effect on the driving force (at a constant degree of subcooling) above a certain pressure range. The experimental results show that in a natural gas-water system at constant degree of subcooling the induction time is not significantly affected by pressure. However, in the presence of the kinetic inhibitor tested in this study, high-pressure conditions decreased the induction time.     

Application of Image Processing and Adaptive Neuro-fuzzy System for Estimation of the Metallurgical Parameters of a Flotation Process

It is a well-known fact in the literature and practice that flotation froth features are closely related to process conditions and performance. The authors have already developed some reliable algorithms for measurement of the froth surface visual parameters such as bubble size distribution, froth color, velocity and stability. Furthermore, the metallurgical parameters of a laboratory flotation cell were successfully predicted from the extracted froth features.

In this research study, the fuzzy c-mean clustering technique is utilized to classify the froth images (collected under different process conditions) based on the extracted visual characteristics. The classification of the images is actually necessary to determine the ideal froth structure and the target set-points for a machine vision control system. The results show that the captured froth images are well-classified into five categorizes on the basis of the extracted features. The correlation between the visual properties of froth (in different classes) and the metallurgical parameters is discussed and modeled by the adaptive neuro-fuzzy inference system (ANFIS). The promising results illustrate that the performance of the existing batch flotation system can be satisfactorily estimated from the measured froth characteristics. Therefore, the outputs from the current machine vision system can be inputted to a process control system.     

基于图像空间结构统计分布的浮选泡沫状态识别

通过泡沫图像统计建模,实现了基于图像空间结构感知的浮选泡沫状态自动识别与客观评价。首先,采用Weibull分布建立了泡沫图像各方向边缘响应结构的统计分布模型,有效获取了泡沫图像空间结构的统计分布细节;然后,通过统计学习获得各典型工况状态下的泡沫图像边缘响应统计分布的混合高斯（MoG）模型;最后,通过简单的贝叶斯推理推断出测试泡沫图像对应的工况状态。结果表明：所提出的方法因有效获取了与浮选生产性能直接相关的泡沫空间结构的统计分布特征,可以实时监视泡沫空间结构的变化情况,泡沫生产状态识别准确率高。     

Hydrodynamics study of two different inverse fluidized reactors for the application of wastewater treatment

We investigated the hydrodynamic characteristics of two types of inverse fluidized bed reactors having different driving force for fluidization: aeration and centrifugal force. In the first reactor, only an upward gas flow allows floating low-density polyethylene beads to sink down into liquid phase and to be uniformly distributed over the entire column. The gas velocity at which the solid concentration is uniform throughout the bed expansion decreases with increasing particle loads. In the second reactor, the particle loads do not greatly affect the critical rotating velocity for the homogeneous distribution of solid particles while the geometry of reactor spacing and the type of impeller are more important for the distribution of particles. For the application of waste-water treatment, the inverse fluidized bed with aeration was found to be more efficient than the second type of reactor.     

子午线轮胎接触变形的非线性有限元分析

建立了９．００Ｒ２０子午线轮胎的有限元分析模型,从轮胎的材料非线性、几何非线性、橡胶帘线复合材料的各向异性,以及橡胶材料的不可压缩性等方面探讨了轮胎与地面的静态接触问题,分析了下沉量、充气压力及静摩擦系数等对轮胎静态接地面内应力应变场的影响。结果表明,在一定的充气压力下,随着下沉量逐渐增大,轮胎接地形状从圆形逐渐变为椭圆形、矩形、接地区应力分布由内高外低逐力下,随着下沉量逐渐增大,轮胎接地形状从圆     

超临界CO2萃取生姜油实验研究与数值模拟

利用自建的超临界流体萃取实验装置,以CO2为萃取剂,考察了萃取压力、温度、流体流量及原料颗粒度等因素对生姜油累积萃取率的影响,由此确定了较佳的萃取工艺条件。基于萃取器微分单元质量守恒原理,建立了数学模型,并利用直线推动力近似理论拟合了总传质推动力及平衡吸收常数,对实验结果进行了数值模拟。