钢管在气力垃圾输送工程的应用及其防腐方法

简单介绍了气力垃圾输送管道的种类和材料。重点介绍了几种不同材质和工艺的钢管及其适用范围,并对其进行了比较,指出了螺旋焊管和直缝焊管各自的特点和优势;详细阐述了埋地气力输送钢管的土壤腐蚀类型及比较常见的防腐方法,重点介绍了目前已在气力输送工程中实际应用的3PE防腐、环氧涂层防腐和阴极保护防腐的工艺流程和特点;最后提出了气力垃圾输送管道应用中存在的一些问题和展望。     

炭黑在气力输送系统中的破碎原因的分析

分析了炭黑在气力输送过程中的破碎机理。通过实验,介绍了气力输送系统中炭黑的种类和炭黑的物性对炭黑的破碎的影响,指出气力输送系统的输送管路长度和布置以及输送参数如输送压力和输送速度等的变化直接影响着炭黑的破碎率的大小。为更好地解决炭黑在气力输送中存在的问题,优化炭黑气力输送系统的设计提供了依据。     

炭黑在气力输送系统中的破碎原因的分析

分析了炭黑在气力输送过程中的破碎机理．通过实验．介绍了气力输送系统中炭黑的种类和炭黑的物性对炭黑的破碎的影响．指出气力输送系统的输送管路长度和布置以及输送参数如输送压力和输送速度等的变化直接影响着炭黑的破碎率的大小．为更好地解决炭黑在气力输送中存在的问题,优化炭黑气力输送系统的设计提供了依据．     

文丘里管流量测量装置的校验和评价

介绍了文丘里管流量测量装置的校验方法,以检验测流装置是否满足使用要求。同时探讨校验中存在的问题。     

亚音速复式双文丘里管在电力、冶金行业气体流量测量中的应用

文章对电力、冶金行业中特殊安装位置气体流量测量中,当前存在的主要问题进行了分析,阐述了双文丘里管及插入式文丘里管的结构、组成、安装形式、特点及应用,特别是在工业领域大型管道的废气、烟气及各类脏污气体的流量测量中的应用优势.     

内文丘里管流量计及应用

本文介绍内文丘里管的工作原理、结构、技术性能及优缺点。内文丘里管(又称环形锥管),是新一代差压式流量测量仪表,是对传统文丘里管做了改型的异型文丘里管,它集经典文丘里管、环形孔板和耐磨孔板计量性能优点于一体,并且在能源计量工作中已取得良好的使用效果。     

基于砂丘模型的气力输送粒子运动特性

针对气力输送过程中存在严重能量损失问题,在水平管气力输送系统的粒子入口附近安装砂丘模型,探讨系统最小压力损失和最小输送速度;为了揭示砂丘模型的节能机理,采用粒子图像测速(PIV)技术和快速傅里叶变换(FFT)分别对各个工况加速区的粒子平均速度和粒子脉动速度进行测量与分析。结果表明:同样的空气输送速度下,安装砂丘模型进行输送时,粒子平均速度和粒子脉动速度的功率谱密度峰值明显大于传统气力输送系统,并且自相关系数呈现准周期变化;粒子脉动速度的两点相关系数明显大于传统的气力输送系统;在管顶部附近,粒子速度脉动强度大于传统的气力输送系统。     

橡胶厂炭黑气力输送系统设计

结合橡胶厂炭黑气力输送系统的使用情况,对输送管道、空气流量控制元件、供料装置、分离过滤设备等主要部件进行优选;对安全阀、减压阀、空气过滤器和Laval管喉径选择进行计算;对输送安全性控制要求和特殊品种炭黑如牌号为N772、N774的炭黑输送管道的选择进行阐述。结果表明,通过对气力输送系统主要设备的优选,可有效减小能耗,减少输送过程中出现的炭黑粒子破坏严重以及管道残余、阻塞、泄漏问题,确保输送系统可靠、平稳运行。     

粉体性能对浓相气力输送特性的影响

气力输送过程中物料性能是确定输送特性的重要因素,因此,粉料气力输送技术的实现要以对粉料的性能研究为基础。文中对影响气力输送的粉体基本性能及其相关参数做了较全面分析,其中粒子尺寸、粒径分布、形状是影响粉料是否可适用于浓相气力输送的关键参数,其它特性都与这3种特性相关联。介绍了几种应用广泛的粉料气力输送特性分组方法,并进行了简要评述,同时指出了今后的研究方向。     

低速高能效的浓相气力输送技术

低速浓相输送装置的出现,解决了物料在输送过程中易破碎、堵塞和磨蚀管道等难题,降低了耗气量。本文中综述了低速浓相输送的几种定义和输送过程中的相图、物料流动形态及相应的判定、影响浓相气力输送特性的因素等技术参数,并介绍了输送过程中经常遇到的堵管和磨损现象以及气力输送过程中的检测和自动控制技术,指出了今后的研究方向。     

密相气力输送系统中几种气量控制方式的比较

从调压范围、压力特性和流量特性方面介绍了减压阀的主要性能,讨论了气力输送交流中减压阀的选择和调节,分析了密相气力输送系统中各种气量控制方法,对其各自的优缺点进行了详细讨论,重点分析减压阀及减压阀与拉法尔联合气量控制系统的优、缺点,表明可调式拉法尔管是今后气力输送气量控制发展的方向。     

CHARACTERISTICS OF A HORIZONTAL SWIRLING FLOW PNEUMATIC CONVEYING WITH A CURVED PIPE

In order to prevent flow blockage phenomenon and to reduce the impact of particles on the wall of the bend, an experimental study of the swirling flow pneumatic conveying system with a horizontal curved pipe was carried out in this work. The experiment was performed in a 90-deg pipe bend with pipe diameter 75 mm and centerline curvature ratio 12. The straight pipes with 75 mm inside diameter at the upstream and downstream of the bend were 1.3 m and 4.0 m in lengths, respectively. The initial swirl number was varied from 0.22 to 0.60, the mean air velocity from 10 to 20 m/s, and the solid mass flow rate from 0.07 to 0.68 kg/s. It is found that in the lower air velocity range, the overall pressure drop of the swirling flow pneumatic conveying shows a lower tendency than that of axial flow pneumatic conveying. The minimum air velocities can be decreased by using the swirling flow pneumatic conveying. From the visualization of particle flow patterns, the impact of particles on the wall of the bend can be reduced using the swirling flow.     

石灰长距离气力输送系统的试验研究

基于气力输送理论,通过石灰的长距离输送试验系统的建立,研究输送过程中耗气量、管道压力损失、物料输送前后的状态等重要输送特性。结果表明,将气力输送应用在长距离的石灰输送上是完全可行的,可解决钢铁行业的高粉尘污染问题,极大地改善工作环境。     

CHARACTERISTICS OF A HORIZONTAL SWIRLING FLOW PNEUMATIC CONVEYING WITH A CURVED PIPE

ABSTRACT

In order to prevent flow blockage phenomenon and to reduce the impact of particles on the wall of the bend, an experimental study of the swirling flow pneumatic conveying system with a horizontal curved pipe was carried out in this work. The experiment was performed in a 90-deg pipe bend with pipe diameter 75 mm and centerline curvature ratio 12. The straight pipes with 75 mm inside diameter at the upstream and downstream of the bend were 1.3 m and 4.0 m in lengths, respectively. The initial swirl number was varied from 0.22 to 0.60, the mean air velocity from 10 to 20 m/s, and the solid mass flow rate from 0.07 to 0.68 kg/s. It is found that in the lower air velocity range, the overall pressure drop of the swirling flow pneumatic conveying shows a lower tendency than that of axial flow pneumatic conveying. The minimum air velocities can be decreased by using the swirling flow pneumatic conveying. From the visualization of particle flow patterns, the impact of particles on the wall of the bend can be reduced using the swirling flow.     

Analysis of Gas-Solids Feeding and Slug Formation in Low-Velocity Pneumatic Conveying

Gas and solids feeding is a key operation in pneumatic conveying of particulate materials. This article presents an analysis of the interfacing effects between a nozzle gas supplier, a rotary valve solids feeder with dropout box, and the pipeline of a pneumatic conveying test rig for low-velocity dense-phase flow. Experiments were carried out to examine the flow pattern of slugs in different combinations of gas flow conditions and solids loading ratios. The effect of gas and solids feeding on the formation of slugs is analyzed by using both experimental data and computer-modeled results. Solids accumulation and sliding motion at the bottom of the dropout box and near the entrance of the downstream pipe, which happen prior to the bulk motion in the form of a slug, are found important in determining the size of a slug. Gas retention and pressure buildup characteristics in the feed section are also found crucial in influencing the flow patterns of slugs.     

The effect of oscillating flow on a horizontal dilute-phase pneumatic conveying

ABSTRACT

A horizontal dilute-phase pneumatic conveying system using vertically oscillating soft fins at the inlet of the gas–particle mixture was studied to reduce the power consumption and conveying velocity in the conveying process. The effect of different fin lengths on horizontal pneumatic conveying was studied in terms of the pressure drop, conveying velocity, power consumption, particle velocity, and intensity of particle fluctuation velocity for the case of a low solid mass flow rate. The conveying pipeline consisted of a horizontal smooth acrylic tube with an inner diameter of 80 mm and a length of approximately 5 m. Two types of polyethylene particles with diameters of 2.3 and 3.3 mm were used as conveying materials. The superficial air velocity was varied from 10 to 17 m/s, and the solid mass flow rates were 0.25 and 0.20 kg/s. Compared with conventional pneumatic conveying, the pressure drop, MPD (minimum pressure drop), critical velocities, and power consumption can be reduced by using soft fins in a lower air velocity range, and the efficiency of fins becomes more evident when increasing the length of fins or touching particles stream by the long fins. The maximum reduction rates of the MPD velocity and power consumption when using soft fins are approximately 15% and 26%, respectively. The magnitude of the vertical particle velocity for different lengths of fins is clearly lower than that of the vertical particle velocity for a non-fin conveying system near the bottom of the pipeline, indicating that the particles are easily suspended. The intensities of particle fluctuation velocity of using fins are larger than that of non-fin. The high particle fluctuation energy implies that particles are easily suspended and are easily conveyed and accelerated.     

Particle dynamics analysis in bend in a horizontal-vertical pneumatic conveying system with oscillatory flow

The pneumatic system is frequently operated in the high air velocity region, which aggravates the power consumption and erosion of bend, and the intensive study of the particles motion characteristic on a horizontal-vertical pneumatic conveying in various curved 90° bends is necessary. This experimental study focuses on the particles motion characteristic of bend on the horizontal-vertical pneumatic conveying with oscillatory flow (generated by installing the oscillator) in terms of on pressure drop, powder consumption, the evolution of particle velocity and particle fluctuating intensity during flowing through bends. The results indicate that powder consumption can be reduced by using oscillatory flow, which is more obvious with a larger radius ratios bend. Meanwhile, the pressure drop proportion of bend is higher than average pressure drop of the system within the same distance. Otherwise, the total reduction particles velocity through bend is less while using oscillatory flow, which is more obvious using larger radius ratios bend. The particle velocity using oscillatory flow is higher than that of the conventional pneumatic conveying for the cases of larger radius ratios bend, and this effect is less evident while through a smaller radius bend.     

An experimental study on a horizontal-vertical pneumatic conveying system using oscillatory flow

To reduce the power consumption of a horizontal-vertical pneumatic conveying system, an oscillator is mounted with a 45° oblique plane through the pipe axis in this study. This experimental study focuses on the effect of oscillatory flow using the oscillator on the horizontal-vertical pneumatic conveying system in terms of the overall pressure drop of the system, power consumption, local pressure drop, and particle velocity. Compared with conventional pneumatic conveying (axial-flow), the pressure drop and power consumption can be reduced using the oscillatory flow in a lower air velocity range. Meanwhile, the particle axial velocity of the oscillatory flow is higher than that of the axial-flow near the bottom of pipe. This outcome indicates that the accelerating effect of oscillatory flow is obvious near the bottom of the pipe, and the particle vertical velocity of the oscillatory flow is positive, whereas the particle vertical velocity of the axial-flow is almost negative. This result shows that the particles of the oscillatory flow are suspended sufficiently, but the particles of the axial-flow have a tendency of deposition. Furthermore, the fluctuation intensity of the particle velocity of the oscillatory flow is higher than that of the axial-flow, especially near the bottom of the pipe.     

Minimum Transport for Dense-Phase Conveying of Granules

The minimum transport or capacity limitation boundary for low-velocity slug-flow pneumatic conveying affects the design and operation of conveying systems. Unfortunately, the relevant mechanisms involved with this boundary still lack full understanding and assessment. Investigations have been carried out to model the capacity limitation for the low-velocity slug-flow pneumatic conveying of poly granules through horizontal pipes. Pipeline diameter, air mass flow rate, and operating pressure have been found to affect the maximum slugging capacity of this material. A semiempirical equation has been established to predict the maximum solids mass flow rate for a given air mass flow rate and conveying pipeline. Good agreement has been achieved between the model predictions and the experimental results over a wide range of airflows and pressures.