宁东灵武矿区煤粉密相输送管道压降研究

采用Barth气力输送理论,通过实验在质量流率1 550—1 700 kg/h的输送范围内,研究了宁东灵武矿区煤粉密相输送的压降和表观气速的关系。结果表明:随着表观气速的增加,水平管道和竖直管道的压降都是先降低后升高,但竖直段的压降变化速度比水平段变化快,水平段的经济气速(4 m/s)小于竖直段的经济气速(7 m/s)。通过计算值与实验值比较,发现理论计算值与实验值偏差在30%以内,说明基于Barth附加压降法对宁东灵武矿区煤粉密相气力输送管阻力特性的计算具有较好的适应性。     

粉煤灰中浓度气力输送管道压降研究

对于粉体气力输送流动区域划出中等浓度区，使浓相输送与稀相输送的区分变得清楚、分析了粉体气力输送管道压降的主要影响因素，在量纲分析基础上，对中浓度气力输送提出一个比较简洁的管道压降关联式，与文献的实验数据进行拟合，结果表明该式可以很好地描述粉煤灰中浓度气力输送管道的总压降。对于给定的一个相图，该式的系数k、有一固定的数值；此值与物料质量流率（或气体质量流率）、料气比无关。     

气力输送系统中输送气体压力的计算

物料利用气体输送系统在输送过程中，输送气体压力的计算是最重要的输送参数之一。是能否稳定、正常输送的关键。本文通过物料在气力输送系统中输送压降的计算。为气力输送系统的设计提供了依据。     

竖直上升管中密相气力输送压降特性

研究了内径20 mm的竖直上升不锈钢管道中粉煤密相气力输送单位管长压降随输送参数的变化规律,并得到了Zenz相图。结果表明,在实验操作范围内管道压降主要由固相自身静压降和固相摩擦压降组成,气相产生的压降不超过总压降的1%;固相体积分数是影响压降变化的主要因素,并讨论了粉煤流速以及固相体积分数对固相静压降和摩擦压降的影响规律;考察了粉煤流速和固相体积分数对固相摩擦系数的影响,对实验数据拟合得到了固相摩擦系数的关系式,计算结果与实验值吻合较好。     

气力输送中弯管压力降的研究

讨论了气力输送中弯管的压力损失,详细阐述了输送过程中各种参数,如输送气速、料气比和弯管弯曲半径、弯管结构及形状对气力输送压降和输送能力的影响,指出不同的物料在弯管结构选择上也应不同。     

负压与低压压送气力输送系统的能耗分析

在相同的输送参数(管道结构、输送能力、压力降及料气比)下,计算出负压气力输送系统和低压压送气力输送系统的技术数据,并详细分析了负压气力输送系统能耗高的主要原因.认为采用低压压送气力输送系统比负压气力输送系统经济效果好,输送效率较高,输送起始速度远低于负压输送系统的起始速度,并可节约能源49%,因此,选用低压压送气力输送系统比负压气力输送系统更节约能耗及降低运行费用.     

基于Aspen Plus的煤粉高压气力输送压降研究

为研究煤粉高压气力输送的管道压降,对Aspen plus中气力输送模型的原理及应用进行了详细介绍,首先用Aspen Plus对纯气相压降进行了模拟计算,回归出气相摩擦因子,气相压降模拟值与实测值误差在10%以内,然后在气相压降计算准确的基础上,对DN10 mm、DN15 mm及DN25 mm三种不同管径的气固两相流压降进行模拟计算,回归出颗粒摩擦系数,气/固两相压降的模拟值与实测值误差在30%以内,最后对输送压力(g)为7 MPa的超高压气/固两相流压降进行了预测分析。     

气力输送系统中输送气体压力的计算

在利用气力输送物料过程中，输送气体压力的计算是最重要的输送参数之一，是能否稳定，正常输送的关键。文中通过物料在气力输送系统中输送压降的计算，为气力输送系统的设计提供了依据。     

基于量纲分析的气力输送压降模型研究

量纲分析法是建立数学计算模型的一种重要的方法。以实验室气力输送数据为基础,结合量纲分析法,建立了管道压降计算准数关联式,同时将计算结果与实验数据进行对比分析,实验值与计算值总体变化趋势基本相同,偏差较小,并对其中误差相对较大的公式进行了修正,所得准数关联式对化工气力输送中压降的估算具有实际意义。     

石灰石粉密相气流输送中试研究

用石灰石粉进行长度分别为62m和167m两种不同输送距离、管径为80mm的中试研究，通过获得的有关水平管、垂直管、弯管的压降数据及不同输送距离条件下的固气比数据，提出了密相技术输送这种粉料的压降的关联式和固气比关联式，再通过计算程序，可以较好地模拟实验过程，说明所获得的计算关联式可以用于石粉输送的工艺设计，为石粉的输送工程设计奠定了基础。     

Study of the pressure drop of dense phase gas-solid flow through nozzle

Pressure drops are measured on different nozzles of various pipe sizes in dense phase pulverized coal pneumatic conveying. From the experimental results, we conclude that the effect of the gas phase nozzle pressure drop is negligible when comparing with the solid phase pressure drop in the experimental range. The main influence factors contributing to the nozzle pressure drop are gas and solid mass flow rate, solids loading ratio, and the diameters of the nozzle inlet and outlet. A new model was developed to predict the nozzle pressure drop in dense phase pneumatic conveying of pulverized coal based on the Barth's pneumatic conveying theory. The pressure drop predictions from the model are in good agreement with the experimental values. The model quantified the important influence factors of the nozzle pressure drop.     

工业级水平管粉煤气力输送的最小压降速度和稳定性

采用压缩空气作为输送介质,在工业级水平管(内径50 mm)上开展了粉煤密相气力输送实验研究。在实验获得最小压降速度基础上,通过电容层析成像系统观察到,随着表观气速降低而存在分层流、沙丘流、移动床流以及栓塞流4种流型。不同流型压力信号的概率密度分布和功率谱密度分析表明,压力信号的波动特征与流型紧密联系;由于流动形态的变化,存在由稳定输送过渡到不稳定输送的临界气速,且该速度小于最小压降速度。     

Resistance Properties of a Bend in Dense‐Phase Pneumatic Conveying of Pulverized Coal under High Pressure

Experiments of high‐pressure dense‐phase pneumatic conveying of pulverized coal with different mean particle sizes using nitrogen were carried out in an experimental test facility with a conveying pressure of up to 4 MPa. The effects of three representative operating parameters (solids‐to‐gas mass flow ratio, conveying pressure, mean particle size) on the total pressure drop were examined. The pressure drops across the horizontal and vertical bends were analyzed by experimental and analytical calculation. The results show that the pressure drop due to gas friction is of much less significance, while the pressure drop due to the solids friction component of the total pressure drop dominates. There exists a relationship between the pressure drop due to solids kinetic energy loss and mass flux of solids.     

垂直稀相气力输送压降特征实验

对Geldart–D类颗粒在高度为18 m、内径为0.05 m的垂直管道中的稀相气力输送特征进行了实验,结果表明：Klinzing, Mathur, Yang和 Caric等提出的预测关联式可以准确预测fs值,135°上弯头、135°下弯头和45°斜管的压力梯度与垂直管道中的压力梯度之比分别为1.6, 2.0和4.0.     

Die Grundlagen der pneumatischen Förderung

Principles of pneumatic conveying . The design of pneumatic conveying systems is critically dependent upon a knowledge of the pressure drop and the minimum necessary velocity of the conveying gas. Starting from the areas of application of pneumatic conveying systems, the conveying states occurring are discussed and appropriately assigned to the diagram of state. The pressure loss equation is reported for conveying in form of a fully suspended flow and strand-type conveying and the theoretically predicted pressure losses are compared with experimental values for the conveying of coarse and finegrained materials. After mentioning the calculation of the pressure drops due to acceleration and to pipe bends, the article discusses the problem of pipe enlargement for long conveying distances. Equations are also given for the calculation of the so-called blocking limit and of the conveying gas velocity at which the minimum pressure drop occurs. The influence of the compressor on the choice of the operating point is also discussed. New calculation equations are then given for horizontal and vertical conveying in form of a fully suspended flow conveying and for horizontal strandtype conveying which permit reliable scale-up. Moreover, a new equation is reported for the blocking limit in horizontal conveying.     

Fluid dynamics characterization of a pneumatic bed using a spouted bed type solid feeding system

The development of a bed is reported, in which characteristics from spouted beds and pneumatic conveying are combined. The apparatus can be described as a pneumatic transport bed modified by the introduction of a recirculation process for inert materials, which leads to a final configuration akin to that of spouted beds. The dependency of the particle recirculation rates on the air flow rates and on the distance between the air inlet and the lower end of the central tube (z₀) was investigated. Also studied was the variation of the total pressure drop with air flow rate, for different loads of inert materials (glass spheres, d_p = 2.8 mm) and different z₀ values.