600MW循环流化床锅炉水冷壁设置防磨梁后炉内气固流场的数值研究

针对600MW裤衩腿循环流化床锅炉水冷壁壁面上设置与不设置多阶式防磨梁情况,采用数值模拟方法研究了防磨梁对炉内颗粒平均质量浓度和颗粒轴向速度、壁面区域颗粒浓度和轴向速度分布的影响,并综合分析了颗粒流对壁面磨损的影响.结果表明:防磨梁的存在削弱了炉膛颗粒轴向速度呈"M"型分布的趋势;水冷壁壁面设置防磨梁后,稀相区下部区域颗粒平均质量浓度略有减小,上部区域略有增大;防磨梁破坏了高质量浓度贴壁颗粒下降流,使得回流区厚度和颗粒下降速度减小,且越靠近壁面,这种影响越明显;2层防磨梁之间特别是防磨梁向炉内凸起的高度范围内,贴壁回流颗粒的质量浓度和下降速度增加速度均比无防磨梁时大;加装防磨梁后,贴壁颗粒流对壁面的磨损量总体上有所减小,但防磨梁附近壁面区域的磨损量相对较大.     

IGCC废热锅炉工程结构特性研究

废热锅炉是IGCC系统高温气化合成气显热回收的关键部件,对IGCC系统运行的稳定性和提高发电效率起着至关重要的作用。通过对国内外典型IGCC系统废热锅炉的结构特点、运行工况等的对比与分析,结果表明:高温辐射废热锅炉的除渣、高温腐蚀、废锅入口堵渣等问题以及对流式废热锅炉的积灰、磨损是确保其可靠运行的关键问题。因此,应针对不同气化工艺流程选择不同的废热锅炉形式。     

1000MW超超临界锅炉水冷壁壁温计算

采用分区计算简化大容量高参数超超临界锅炉炉内辐射、对流传热模型,研究炉膛水冷壁热负荷及壁温的空间分布情况,并与试验数据进行了对比,计算结果与试验值之间的偏差较小,最大为5.72%.该模型与算法可给出不同锅炉负荷条件下,水冷壁壁面热负荷与壁温沿炉膛宽度方向的分布规律.结果表明,水冷壁热负荷与壁温均呈现出中间高两端低的弧形分布.四角切圆燃烧锅炉火焰位置对炉内传热有很大影响.模拟计算可为超超临界锅炉的运行提供参考,预测了在材料允许温度范围内,火焰中心偏斜最大不超过2 m.     

燃煤锅炉三维CFD数值模型水冷壁热边界条件设定方法

目前,燃煤锅炉三维CFD数值模拟中对炉膛水冷壁传热分布的预测大都基于给定的壁面温度边界条件。然而,此方法无法体现锅炉运行状态对壁面传热与壁温分布的影响。提出了一种基于锅炉烟气侧放热与汽水侧吸热间热平衡关系的壁面传热计算方法,并重点讨论了壁面传热系数的物理意义及取值方法。研究发现,壁面传热系数基本由壁面结渣状态决定,因此可根据壁面渣层的传热系数确定。本文方法将影响壁面传热的关键因素合理地体现在计算过程中,同时在模型复杂性与工程适用性之间保持了合理的平衡。采用此方法对一台320 MW锅炉的燃烧与传热分布进行了数值模拟,水冷壁吸热量的预测结果与锅炉运行数据吻合良好。     

循环流化床锅炉水冷壁磨损问题探讨

循环流化床锅炉水冷壁磨损在运行中存在的主要问题及采取有效的措施来降低水冷壁的磨损,提高了循环流化床锅炉运行安全性、稳定性和经济性。     

CFB锅炉水冷壁的防磨措施

针对某公司CFB锅炉掺烧后出现的水冷壁磨损问题,分析引发磨损的多种原因,采取针对性防磨措施,取得良好的效果,提高了锅炉运行的安全性和稳定性,对同类型的CFB锅炉预防水冷壁磨损具有一定的参考价值.     

CFB循环流化床锅炉磨损机理及对策

结合运行实际分析了颗粒浓度、流动形式以及燃料特性等因素对CFB锅炉炉膛磨损的影响,并进一步探讨了CFB循环流化床锅炉磨损的机理,提出了防止水冷壁磨损可以采用的技术措施以及产品研发和运行管理上用于预防磨损的建议.     

循环流化床锅炉水冷壁管束的磨损及预防

循环流化床燃烧技术是近二十年迅速发展起来的一种洁净煤燃烧技术.循环流化床锅炉具有煤种适应性强、燃烧效率高、污染物排放低和负荷调节性能好等优点,是目前推广应用的炉型之一.但是,由于炉内有大量的床料及循环物料,煤在物化状态下低温循环燃烧,造成烟气中含有大量的飞灰颗粒,这些灰粒高速冲刷水冷壁管、对流受热面等部位,使其壁面受到剧烈磨损,发生局部的严重破坏,甚至导致停炉事故.目前随着过热器和省煤器防护技术的成熟,磨损得到较好的控制,但是水冷壁管束的磨损控制还在摸索中.因此,了解飞灰磨损规律,找出主要磨损部位及原因,选择合理的防磨措施,进行合理的技术改造,保持锅炉最佳方式运行,使磨损损害减少到最小程度,无论从安全或经济上都是非常必要和及时的.     

循环流化床锅炉中水冷壁的磨损原理及其预防

循环流化床锅炉水冷壁管的磨损是影响循环流化床锅炉运行的一个主要因素.总结了循环流化床锅炉中水冷壁管的磨损情况,根据其磨损机理分析了预防磨损的措施.磨损的根本原因是气固两相流场造成的,因此改善易磨损部位的流场可以减轻磨损.采用厚壁水冷壁管、降低流化速度,也可以有效防止磨损爆管.运行经验表明,这些措施能大大地改善磨损情况,延长水冷壁管的使用寿命.     

超临界四角切圆燃烧锅炉运行方式对水冷壁高温腐蚀影响的试验研究

针对某630 MW超临界四角切圆燃烧锅炉水冷壁存在的高温腐蚀问题,对水冷壁近壁面烟气成分(O2、CO及H2S)进行了测试,分析了运行O2体积分数、煤粉细度、入炉煤含硫量、紧凑燃尽风(CCOFA)风量、分离燃尽风(SOFA)风量及周界风量等因素对水冷壁高温腐蚀及NOx排放特性的影响.结果表明:高温腐蚀发生区域表现出明显的强还原性气氛;增大运行O2体积分数,同时保证风量沿炉膛高度方向上的合理分配可减弱水冷壁近壁面还原性气氛;煤粉细度对水冷壁近壁面还原性气氛的影响较小;随着入炉煤含硫量的增加,水冷壁近壁面H2S体积分数增大,O2和CO体积分数则变化不大;较小的CCOFA风量及适当的SOFA风量有利于减轻水冷壁高温腐蚀;周界风量对主燃烧区下部壁面区域还原性气氛的影响较大,运行时应适当减少周界风量.     

小型锅炉烟尘测试时锅炉出力的计算

锅炉烟尘测试时,必须对锅炉出力进行测试。但监测中,许多小型锅炉往往不具备相关的计量装置和仪表,为解决这一问题,文章提出了用烟气量和空气过剩系数来计算锅炉的出力的公式,在实际使用中,该方法简单易行,其结果和实测值具有很好的一致怀。     

Unerroric of control of mutual compliance of the efficiency of hydrogen engines of unmanned vehicles in the conditions of mass production

The issues related to the reliability of hydrogen engines of unmanned vehicles and increasing the efficiency of using hydrogen as fuel when using the method of its production during the decomposition of hydrogen-containing molecules of liquid-phase organic compounds in a plasma discharge under the action of intense ultrasonic exposure are considered. Experiments have shown that as a result of decomposition in the acoustoplasma discharge of liquid hydrocarbons, solid-phase carbon-containing products are formed, chemical transformations occur in the liquid phase and hydrogen-containing combustible gas is formed. Hydrogen-containing gas can be used as fuel immediately after synthesis, i.e. it does not require separation, since in addition to hydrogen it contains only impurities of CO₂ and water vapor. The purpose of the study is to formalize the basic conditions for tightening the control of mutual compliance with the efficiency of hydrogen engines of the same series in the conditions of their mass production. Methods of mathematical statistics and hardware-software modeling were used in the study. The term “unerroric of quality mutual compliance control” is introduced to describe a set of hardware and software tools for such control. The principle of in-depth testing of the technical condition of such engines of one series is described in a multidimensional formulation of the quality control problem for three of their operating parameters at once. The conditions for increasing the mutual correspondence of the measured values of such parameters in the conditions of serial production of hydrogen engines are formalized.     

中国煤炭地下气化技术的发展

本文综述了煤炭地下汽化技术的国内外发展现状,对我国“长通道、大断面”煤炭地下气化新工艺给予了技术经济评述,并提出了发展煤炭地下汽化技术的政策建议。     

Review of theory of distortion and disintegration of liquid streams

Linear and nonlinear analyses of the instabilities and distortion of liquid streams injected into a gaseous media are discussed. The various fundamental mechanisms and the predictive capabilities for the distortions are emphasized. Round jets, planar sheets, annular sheets, and conical sheets are discussed in detail. The balance between capillary and inertial forces is primarily examined. The method for simplifying the analyses in the case of thin liquid sheets is discussed. The capabilities for representing the droplet size distribution that follows the stream disintegration are outlined.     

MgO膨胀剂细度对MgO水化和水泥浆体膨胀的影响

基于《水工混凝土掺用氧化镁技术规范》中的Ⅰ型氧化镁（MgO）,研究了该型MgO膨胀剂（MEA）细度对掺粉煤灰水泥浆体膨胀性能的影响。即采用X射线衍射分析(XRD)及同步热分析（TG DSC）分析了掺MEA水泥浆体中MgO的水化性。结果表明,养护温度相同时,MEA的细度对水泥浆体内MEA中MgO的水化和水泥浆体的膨胀无显著影响,产生的膨胀均能补偿水泥浆体的收缩;MEA的细度可从试验设计采用的45 μm筛筛余15%左右增加到30%左右,这将有利于MEA生产企业的节能降耗。     

机车车轮多轴疲劳强度安全评定的研究

使用ANSYS8.0软件对高速列车车轮进行了三维有限元分析,计算出车轮在直线、曲线和道岔条件下牵引、制动共6种工况时孔边薄弱部位的应力,分别通过Mises等效平均应力方法、Sines平均主应力方法和应力分量中考虑平均应力方法计算出应力在极值位置时的等效应力幅、等效平均应力,从而进一步算出车轮的安全系数,对其疲劳强度进行评定,并对3种方法进行了比较研究。     

Constructal optimization of the geometry of an array of micro-channels

This paper documents the geometric optimization of an array of circular and non-circular ducts. The optimization was carried out numerically using finite volume method. As optimal dimensions were independent of the array configuration, the numerical simulation was performed on a unit cell. Numerical optimization for circular, square and isosceles right triangle cross-sections of channels was performed. Based on the results of this investigation, some correlations were proposed to predict the optimal hydraulic diameter and dimensionless heat transfer per unit volume. In addition to examining the effect of pressure drop on these parameters, it was showed that among the different geometries of this study, square cross-section has the most efficiency for a given volume. The numerical results of the present study were compared with approximate results reported in the literature which a good agreement was observed.     

固体热辐射Yong性能分析

本文对漫灰均温物体在常物性条件下对外辐射传热的Ｙｏｎｇ值计算建立了数学模型。通过与物体内能Ｙｏｎｇ公式的数值计算比较,得出了辐射能量的Ｙｏｎｇ值不大于内能Ｙｏｎｇ值的结论。从初步的热射Ｙｏｎｇ值计算公式发现。Ｙｏｎｇ与物体表面辐射率有关。     

Measurements of concentration distribution of hydrogen jet using deflection of center of the laser spot

The main purpose of this work is to propose a new method to evaluate the concentration distribution of the hydrogen jet by using a He–Ne laser through the jet. This research attempts to apply the expression of concentration Gaussian distribution, the refraction formula of inhomogeneous refractive index medium, and the concentration inversion function to disclose the displacement of the center of the laser spot at different heights in the gas jet. The spot images of the laser beam passing through the gas jet at three vertical heights z = 10d, 20d, 30d, and different radial positions are obtained. The radial spatial asymmetry of the gas jet is also found in the experiment. Finally, the calculated concentration distribution curve and the fluent simulation curve, it is found that the two results are very similar. Our findings show that the error between the concentration distribution of this method and the simulated concentration distribution reaches 2.43%.     

Heat of vaporization of mixtures

General expressions for the heat of vaporization of mixtures at constant pressure; at constant temperature; and at constant pressure, temperature, and composition are proposed. The last one is related to the liquid-vapor interface where steady vaporization or condensation is taking place. Numerical examples by the proposed expressions are shown for binary mixtures of HCFC22(R22) and (HCFC123(R123) © 1997 Scripta Technica, Inc. Heat Trans Jpn Res, 25(1): 12–24, 1996