浮选柱充气率的影响因素探讨

采用液位上升法,利用射流发泡器研究了充气速率和起泡剂浓度等操作参数对浮选柱充气率的影响规律。结果表明,浮选柱的充气率随着充气速率的增加急剧上升,随着起泡剂浓度的增加缓慢升高,两因素增加到一定值时,充气率达到最大值。     

硫化后充气压力和时间对航空轮胎性能的影响

选取27×7.7－15航空轮胎作为研究对象,通过分析轮胎胎体帘线张力与充气压力的关系以及帘线收缩率、收缩力与温度的关系,并通过热电偶测温法测量轮胎硫化后充气过程中温度随时间的变化情况,确定轮胎最小硫化后充气压力设为200 kPa,可以保证轮胎在胎体温度为160～170 ℃时出模胎体帘线不产生热收缩;硫化后充气时间设定为1个硫化周期,可以保证轮胎冷却至环境温度。成品轮胎充气外缘尺寸及动态模拟试验验证了后充气压力和时间选取的合理性。     

充气速率对全复合材料车用天然气气瓶强度的影响

以某全复合材料车用天然气气瓶为研究对象,针对气瓶充气过程中几种常见的速率,研究了充气速率对含缺陷在役气瓶强度的影响.首先,在气瓶的几个典型部位设计了不同长度和深度的损伤来模拟在役气瓶的缺陷,并建立了数值模型.然后运用子模型法,在不同的充气速率下对各个损伤部位进行计算和分析.结果表明,随着充气速率的增加,气瓶的应变率增大,损伤附近的等效应力明显增大.分析结果为今后充气速率的选取提供了一定的依据,同时也为气瓶强度的检验提供了参考.     

己二胺储罐充气顶升施工技术措施

文章介绍VN=3000m3己二胺不锈钢储罐施工的技术措施,储罐施工采用充气顶升倒装法,主要的施工设备为鼓风机装置。文章重点介绍了充气顶升法鼓风机的使用方法;密封装置和紧固装置的应用;以及储罐组对顺序和焊接过程的施工要点。与其它施工工艺相比:采用充气顶升倒装法施工方便快捷、节省手段用料、降低施工成本。     

10000m^3立式钢油罐的充气顶升安装

介绍了国内罕见的采用充气顶升法安装１００００ｍ＾３立式钢油罐的详情。     

充气中空玻璃评价方法及性能优势

介绍了充气中空玻璃的优势,以及热塑性暖边充气中空玻璃和槽铝式充气中空玻璃的测试标准和评价方法,其中热塑性暖边充气中空玻璃整体性能优于槽铝式充气中空玻璃。     

热力学第一定律在充气过程求解中的应用

运用热力学第一定律求解各种充气过程。根据被充气容器是否刚性,将容器分为刚性容器、柔性容器和弹性容器;根据被充气容器是否绝热,将充气过程分为绝热或等温充气等过程。通过对充气过程典型题型的分析,深入研究了各种充气过程的求解方法。对于工程热力学的课程教学和工程应用具有一定的参考价值。     

全球非充气轮胎市场概况及专利技术分析

非充气轮胎英文全称为Non-Pneumatic Tire,缩写为NPT。非充气轮胎具备不需充气、耐用、易翻新和防爆等特征。与标准子午线轮胎的工作效率和操纵性相比,非充气轮胎在高速行驶状况下会遭受较大的震动。非充气轮胎技术省去了充气轮胎在使用前检查胎压并经常充气的环节,其特殊的结构设计使轮胎原料成本大大削减,且具有优良的安全性能,解决了易被扎破甚或爆胎引发安全事故的缺陷问题,使非充气轮胎成为轮胎研究发展的又一亮点。     

充气压力对充气工况载重斜交轮胎影响的有限元分析

进行了充气压力对充气工况载重斜交轮胎影响的有限元分析.结果表明,充气工况下,充气压力对斜交轮胎外形轮廓尺寸影响明显,其外直径、断面宽度均随充气压力的增大而增加;充气压力的大小对胎圈接触应力分布影响很小,但胎圈最大接触应力随充气压力的增加而增大.     

二氧化碳泡沫封窜体系筛选与评价

CO_2泡沫控制气窜、改善流度比,是目前较热门的一种封窜方法。当泡沫在孔隙介质中渗流时,其渗流特性非常独特,能改善驱替流体在非均质油层内的流动状况,并有效地降低气体流度。实验采用CO_2气体充气法筛选出稳定起泡剂CY-I,并采用Ross-Miless法评价起泡体积为435ml,半衰期244min,用CO_2气体充气法评价,半衰期82min,体系表面张力30.3mN/m,界面张力0.41mN/m,表界面张力较低,能在地层中起到一定的驱油作用。实验结果表明:CY-I起泡剂与注入水配伍性好,经泡高仪Ross-Miles法和充气法检测,起泡能力强和半衰期长。     

The effects of air and particle density difference on segregation of powder mixtures during die filling

Segregation of mono-disperse binary mixtures with different particle densities during die filling in the presence of air was numerically analysed using a coupled discrete element method (DEM) and computational fluid dynamics (CFD) approach. Die filling with powders of different particle density ratios (i.e. the ratio of the heavy particles to the light particles) at various shoe speeds was simulated, in order to explore the effects of air and particle density difference on segregation. For die filling from a stationary shoe, the air can induce significant segregation by hindering the deposition of light particles (i.e., air-sensitive particles). As the particle density ratio increases, the light particles are deposited into the die at even lower speeds compared with the heavy ones due to the effect of air drag, resulting in an increase in the degree of segregation. For die filling with a moving shoe, segregation occurs due to different post-collisional velocities resulting from different particle inertia; and the degree of segregation increases as the particle density ratio increases due to the increasing difference in particle inertia. It is found that, as the shoe velocity increases, the powder flow pattern changes from nose flow dominated to bulk flow dominated and the degree of segregation generally decreases. The effect of air is limited for nose flow dominated die filling because the air can easily evacuate through the gap between the die walls and flowing powder stream. When bulk flow dominates in die filling, the air can be entrapped in the die, which has a significant impact on the powder flow and segregation behaviours. Finally, the effect of interparticle friction on segregation was investigated.     

A coupled DEM/CFD analysis of the effect of air on powder flow during die filling

Die filling from a stationary shoe in a vacuum and in the presence of air was numerically analyzed using an Eulerian‐Lagrangian model, which employs a discrete element method (DEM) for the particles and computational fluid dynamics (CFD) for the air with a two‐way air‐particle interaction coupling term. Monodisperse and polydisperse powder systems have been simulated to explore the effect of the presence of air on the die filling process. For die filling with monodisperse powders, the influences of particle size and density on the flow behavior were explored. The numerical simulations revealed that the presence of air has a significant impact on the powder flow behavior, especially for systems with smaller and/or lighter particles. Flow has been characterized in terms of a dimensionless mass flow rate, and it has been shown that for die filling in a vacuum this is constant. The flow characteristics for die filling in air can be classified into two regimes. There is an air‐inert regime in which the particle size and density are sufficiently large that the effect of air flow becomes negligible, and the dimensionless mass flow rate is essentially identical to that obtained for die filling in a vacuum. There is also an air‐sensitive regime, for smaller particle sizes and lower particle densities, in which the dimensionless mass flow rate increases as the particle size and density increase. The effects of particle‐size distribution and adhesion on the flow behavior have also been investigated. It was found that, in a vacuum, the dimensionless mass flow rate for polydisperse systems is nearly identical to that for monodisperse systems. In the presence of air, a lower dimensionless mass flow rate is obtained for polydisperse systems compared to monodisperse systems, demonstrating that air effects become more significant. Furthermore, it has been shown that, as expected, the dimensionless mass flow rate decreases as the surface energy increases (i.e., for more cohesive powders). © 2008 American Institute of Chemical Engineers AIChE J, 2009     

Determining the accuracy of batching during pneumatic blowing of refractory semidry bodies

Summary During the filling of molds with semidry refractory bodies from one batch with compressed air, we get quite accurate filling.The filling accuracy improves with increase in the ratio of height of the mold to its area in plane.The distribution of the results of filling corresponds to the normal law.When molds are filled with pneumatic blowing, the coefficient of densification is much higher than for other methods of filling.     

回转窑热工状况影响参数的数值模拟

以某炭素厂φ2.3 m×55 m的回转窑作为研究对象,运用流体模拟软件Fluent 和Matlab 分别对回转窑内气体空间和物料料层内的传热过程进行了模拟,预测了回转窑参数如二、三次供风量和位置、翻料装置、物料填充率、窑转速等对窑内温度场的影响。结果表明合理布置二、三次风供风量和位置、设定翻料装置的尺寸和个数能够有效提高窑内温度,进而提高煅后焦质量;合理增加物料填充率和提高窑转速既能够提高回转窑产能,又能够保证煅后焦质量。     

Effect of feed concentration and inlet air temperature on the properties of soymilk powder obtained by spray drying

In this study, soymilk powder was produced by spray drying. The inlet air temperature of spray dryer was varied from 200 to 280°C and the feed concentration was varied from 15 to 25% (w/v). Response surface methodology was used to examine the effects of these independent variables on the detailed characteristics in terms of physical, structural, functional properties of powder. Overall, results show that rising the inlet air temperature caused a decrease in tapped and loose bulk density, true density, filling rate, water holding capacity, and water content of powder; and an increase in compressibility, Hausner ratio, porosity, interstitial air volume, and wettability index. An increase in feed concentration led to an increase in true density, compressibility, Hausner ratio, porosity, interstitial air volume, and wettability index; and a decrease in tapped and loose bulk density, filling rate, water holding capacity, and water content; whereas oil holding capacity might be increased or decreased and it depended almost solely on the feed concentration.     

浅析低温液体运输车罐体的补砂工艺

根据低温液体运输车罐体的夹层补砂的技术问题。设计在补砂期间防止湿空气进人夹层的工艺。使补砂后抽空时间大大缩短。提高了补砂的工作质量和效率。     

Packaging of yield stress fluids: Flow patterns

The packaging or filling of a container with a non‐Newtonian fluid without quality failures is a current issue encountered at the final step of industrial product processes. In this work, the container filling of viscoplastic fluids is studied using an experimental laboratory plant able to reproduce the industrial transitory packaging conditions. First, a Newtonian validation was conducted to compare and to confirm our setup results with available literature data. Second five flow patterns including dripping, jet buckling, mounding, planar filling, and air entrainment were observed and characterized for the viscoplastic container filling. Most of them present different types of instabilities during the filling, except the planar filling, which seems to be ideal according to industrial specifications. A flow pattern distribution depending on relevant dimensionless numbers was developed. Finally, flow pattern transition criteria are determined highlighting the influence of rheological and process parameters on container filling. © 2017 American Institute of Chemical Engineers AIChE J, 64: 1117–1126, 2018     

Estimation of the air permeability of needlepunch materials

The effect of the structure of needlepunch materials on their air permeability is a function of the structural parameters and combinations of these parameters selected. The filling factor does not reflect the effect of the structure of the needlepunch materials on their air permeability; using it together with the surface density is optimum. The effect of the needlepunching conditions on the air permeability of materials is determined with combinations of the filling factor and thickness. __________ Translated from Khimicheskie Volokna, No. 6, pp. 23–25, November–December, 2007.     

改性磷石膏在低气压环境下的试验研究*

为了利用改性磷石膏制备磷石膏制品用于墙体充填材料中,本文研究了不同低气压和低气压养护时间对磷石膏密度、抗压强度、吸水率及渗透性的影响。结果表明,养护3 d和28 d磷石膏砂浆的密度都在0.7 kPa时相对最小,随着低气压养护时间延长磷石膏砂浆密度降低;在3 d和28 d,低气压养护下磷石膏砂浆抗压强度均高于气压为1 kPa时的抗压强度,在28 d,磷石膏砂浆的抗压强度在0.7 kPa时表现出最大的趋势;不同低气压和低气压养护时间下磷石膏砂浆的抗压强度均满足砂浆MU5.0的要求,但对吸水率和渗透性的影响均较小。因此,磷石膏制品不仅能作为房屋装饰材料,也能作为房屋墙体填充材料,且能有效减轻其荷载进而提高抗震能力。     

Numerical analysis of density-induced segregation during die filling

In this study, segregation behaviour of binary granular mixtures with the same particle size but different densities during die filling in the presence of air was investigated using a combined discrete element method (DEM) and computational fluid dynamics (CFD) approach, in which the kinematics of particles was modelled using DEM, the motion of air was analysed using CFD and a two-way coupling of the particles and the air was incorporated. The depositions of powder from stationary and moving shoes into the die cavities of different geometries were simulated and the corresponding segregation behaviours were analysed. It has been found that, for die filling from a stationary shoe, the concentration distributions of the heavy and light particles along the die width mainly depend on the initial spatial distribution of the granular mixture in the shoe. For die filling from a moving shoe, a low concentration of light particles on the leading side of the die (referring to the direction of the shoe motion) is observed for die filling with a square die, in which the process is dominated by nose flow. The density difference can cause segregation along the die depth with a low concentration of light particles at the bottom. The presence of air enhances this segregation tendency by resisting the flow of light particles into the bottom of the die and causes a higher concentration of the light particles at the top. Finally, the segregation index, defined as the volume weighted root-mean-square deviation in the content of light particles, was introduced to quantify the degree of segregation in the horizontal and vertical directions. It has been found that the degree of segregation is determined by the presence of air and also the powder flow pattern.