共查询到20条相似文献,搜索用时 78 毫秒
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对导叶式旋风管内气、固两相进行数值模拟,从颗粒在排尘锥内不同位置的碰撞概率、返混情况、停留时间分布3个方面对颗粒的运动情况进行描述,研究不同流动参数下颗粒的运动变化。结果表明,在排尘锥两侧缝环面的重叠处,颗粒的碰撞概率达到最大值,此处结垢和磨损的可能性较大;随着颗粒粒径的增大,直接捕集的比例增大,排尘锥返混和灰斗返混的比例减小,并且排尘锥返混多于灰斗返混;在一定的流量范围内,随着流量的减小,颗粒返混现象加重,并且随着粒径的减小,相同粒径的颗粒在分离空间内和排尘锥内停留时间延长的幅度变大,返混现象更加明显。 相似文献
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试验测定和对比页岩灰和流化催化裂化三旋灰(FCC三旋灰)的旋风分离器性能,考察入口气速、入口浓度对分离效率和分离器压降的影响.结果表明,在相同操作条件下,同一台旋风分离器上,粒度小于75 μm的页岩灰与FCC三旋灰的分离效率和分离器压降曲线差别显著;页岩灰的分离效率与分离器压降都明显低于FCC三旋灰,且入口浓度增大,页岩灰分离器压降的下降幅度高于FCC三旋灰;页岩灰分离效率最高的入口气流速度也低于FCC三旋灰.颗粒特性对旋风分离器的分离性能有明显影响,页岩灰和三旋灰的颗粒特性与形状差别是导致其旋风分离特性不同的一个基本原因;油页岩旋风分离器的设计应当考虑油页岩颗粒特性的影响. 相似文献
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利用计算流体动力学软件FLUENT对旋风分离器内气固两相流动特性进行三维数值模拟,模拟气相流场采用雷诺应力模型,应用随机轨道模型模拟湍流流场中颗粒的运动轨迹,同时给出了不同抽气率下旋风分离器的速度、压力分布,计算出旋风器分级效率,模拟结果与文献实验数据吻合较好.结果表明,灰斗抽气可以提高锥体内旋转气流切向速度,轴向速度减少能够降低气流携带颗粒返混能力,并减小排气芯管下口短路流,提高旋风分离器分离效率.对于给定的旋风分离器,抽气率应有一最优值. 相似文献
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针对底部结构复杂的高危裂缝钢混烟囱爆破拆除复杂环境的情况,布设合理的爆破切口、定向窗、卸荷槽,并对底部门斗、灰斗、灰斗支架、烟道口立柱等进行预拆除;封堵爆破切口外出灰口,准确控制倒塌中心线方向。在待保护厂房及油罐处架设拦挡网,拦挡爆破产生的飞散物和烟囱倒塌引起的触地飞溅物;倒塌方向铺设5条柔性缓冲堤,用于降低烟囱塌落振动、减弱触地飞溅。切口及烟囱底部"井"字形横梁处炮孔起爆后,烟囱沿设计倒塌中心线方向倾倒,没有出现偏移与后座。爆破后烟囱解体充分、混凝土与钢筋分离度高、块度小,取得了较好的爆破效果。施工用时短,为后续工程的进行创造了条件,争取了时间。 相似文献
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针对旋风分离器顶部灰环逃逸现象,采取在升气管根部开孔直接导出顶灰环中颗粒的方法,以探究顸部灰环在环形空间的分布形态及粒径分布特性。实验在升气管圆周的8个位置分别开孔并试验,通过粗粉收率的变化判断顶灰环中颗粒的逃逸量,并分析了细粉中的粒径分布。发现顶灰环中颗粒逃逸的量是由于顶灰环在空间分布不均造成的,而且在空间的粒径含量和分布是一个动态平衡过程。实验数据袁明相对于升气管开孔前的收率下降了0.37%-5.5%,压降下降了20.1%-40%。最大效率可达97.47%,最低压降可达176.4Pa。 相似文献
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A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling. 相似文献
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Liebert A Wabnitz H Grosenick D Möller M Macdonald R Rinneberg H 《Applied optics》2003,42(28):5785-5792
A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue. 相似文献
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本文根据多年的实践检定经验 ,参照JJF1 0 59- 1 999《测量不确定度评定与表示》以及《测量不确定度表达 1 0讲》 ,对卧式金属罐容量的测量结果不确定度进行了评定。 相似文献
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An approximate analytical expression is derived for the velocity of the front of the wave of change of boiling modes on a
rod and on a plate. The impact of the Thomson effect and of the heater orientation in the gravity field is included. Adequate
agreement is demonstrated between the derived relations and experimental data. 相似文献
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Conventional methods for summation of direct measurement errors are considered. Conditions under which these methods provide consistent results are stated. It is proposed to utilize for characteristic of the total error, its interval estimator or the half-sum of the value obtained by adding up its arithmetic and geometric random errors.Translated from Izmeritel'naya Tekhnika, No. 4, pp. 10–12, April, 1995. 相似文献
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由于空压机进气侧轴承箱蜗壳温度探头密封效果不好,使空压机及其后续管道受到油污染。后将温度探头的O形圈密封改为骨架油封,杜绝了轴承箱漏油问题。文章简介空压机的结构和技术参数,详细介绍了骨架油封的制作和优点。 相似文献