水煤浆流经局部管件阻力特性研究

通过对水煤浆在局部管件中的流动阻力特性分析,采用量纲分析方法得出阻力准则式,用于计算水煤浆流经不同的渐缩管道以及突缩管道的阻力损失,并得出随着流速的增加渐缩段和突缩阻力损失系数逐渐 降低,最后趋于稳定.采用压降比与广义雷诺数的关系说明水煤浆流经不同弯曲率、不同管径弯管时的阻力特性,指出弯管段的阻力损失主要是由不规则流动和弯管轴线加长共同作用的结果.     

水煤浆流经局部管件的阻力损失和均配规律

在中试试验台上研究了水煤浆流经直管、渐缩管、突缩管以及90°水平弯管的阻力特性,分析了渐缩角、管径比以及弯径比对上述局部管件阻力损失和均配的影响.结果表明,渐缩角的增加使得渐缩管的局部阻力损失减少;水煤浆流经突缩管的局部阻力损失先下降然后迅速地增加,同时存在一个最佳弯径比,使得水平弯管的局部阻力损失最小.随着雷诺数的增加,渐缩管当量长度与管径比值(Le/D)逐渐下降然后趋于稳定;突缩管则先下降再增加,而对于弯管成线性增加.弯管的摩擦阻力损失之比随着De的增加而迅速增加.     

水煤浆流经渐缩管段的局部阻力特性

在中试试验台上研究了水煤浆流经渐缩管的局部阻力特性,分析了滑移产生的机理,采用一种新的滑移修正方法确定了水煤浆的真实流变模型,同时获得了水煤浆流经渐缩管时局部能量损失的计算方法.运用非均相流模型和量纲理论,提出了水煤浆流经渐缩管段时局部阻力系数的准则式,发现随着广义雷诺数的增加,渐缩管局部能量损失系数先下降然后逐渐趋于稳定,同时根据试验结果获得了计算局部能量损失系数的经验公式.     

90°水平弯管内水煤浆的阻力特性试验研究

在水煤浆综合输送中试试验台上,将管径为50mm的90°水平弯管配以不同弯径比,对神华煤水煤浆进行了阻力特性试验研究。根据试验结果,对弯管内水煤浆的局部压力损失、摩擦阻力损失及弯管内流动有效长度等方面的一些特性进行总结。结果表明:采用合理的定义及方法,水煤浆弯管内流动的一些特性存在较为明显的规律。     

高浓度水煤浆的流变特性和流动规律研究进展

综述了高浓度水煤浆的流变特性、流动特性、阻力特性和均质稳定输送等方面实验和理论研究的国内外最新进展.深入讨论和分析了水煤浆的流变学属性及影响因素,探讨了浆态非牛顿流体流变特性的理论和实验分析方法中涉及的某些不确定性问题和解决方案,阐述了水煤浆管内输送的滑移机理及其对流动的影响.结合非牛顿流体力学、液固两相流、数值模拟和分析以及模化实验等先进的研究手段,提出了高压、高浓度水煤浆在流变特性、流动特性、阻力特性和均配规律等方面进一步深化研究的设想和思路.     

竖直弯管内水煤浆局部阻力特性的研究

在中试试验台上对水煤浆流经竖直弯管的局部阻力特性进行了研究,分析了水煤浆在竖直弯管内流动的最佳弯径比,并利用多种阻力特性分析方法对试验结果进行了处理.结果表明:水煤浆流经竖直弯管时存在最佳弯径比;竖直弯管内的流动有效长度和摩擦阻力损失比存在较明显的变化趋势,且受弯径比影响较大;利用经验公式对竖直弯管内的局部阻力损失系数与雷诺数的关系进行拟合,尽管存在弯径比的影响,但拟合误差较小,能满足工程实际应用;将De改进为De′,对摩擦阻力损失与De′的关系进行拟合,可以很好地消除弯径比的影响,得出拟合误差更小、能更好地指导工程实际应用的经验公式.     

水煤浆流经小曲率半径弯管的阻力特性研究

在自制试验台上研究了水煤浆流经小曲率半径90°水平弯管的局部阻力特性,分析了不同的曲率半径Rc对弯管的局部压力损失、压力损失系数以及摩擦阻力损失之比的影响.结果表明:随着雷诺数Re的增加,弯管的局部压力损失增大,而压力损失系数先降低后增加.考虑到曲率半径较小,弯管的局部压力损失由不规则流动损失与弯管轴线加长所产生的沿程阻力决定.弯管曲率半径越大,临界雷诺数就越大.弯管摩擦阻力损失之比随着Dean数的增加先降后升.Rc/T为4.0的弯管的局部压力损失、压力损失系数以及摩擦阻力损失之比均最小.     

基于场协同管件的局部阻力损失的CFD数值分析

针对管件局部阻力损失的问题,分别以突缩管、渐缩管、直管为研究对象,采用CFD技术对以水为流体的管件内流动的五种方案进行了数值模拟,获得各管件的压力场及速度场,基于场协同原理对其速度与压力梯度的协同效果进行分析和比较,获得管件内流体流动的局部阻力损失的影响因素及其机理,为工程上的设计和开发低流动阻力的管件提供了理论依据。     

直管内水煤浆流动阻力的数值实验

运用非牛顿流体模型对水煤浆流经直管进行数值模拟,通过压差实验值与计算值的比较验证计算模型的正确性.基于正确的计算模型,进行数值实验,研究沿程阻力系数.总结得出水煤浆流经直管时沿程阻力系数的经验公式.通过对速度场的分析,得出水煤浆流动的核心区.     

高浓度水煤浆的流动特性

讨论和分析了高浓度水煤浆的管内流动特性,阐述了影响水煤浆流动特性的若干因素,综述了水煤浆管内流动阻力特性的理论和计算方法。在分析探讨水煤浆“滑移层”的机理及其对管内流动影响和修正的基础上,介绍了表征水煤浆流动状态的相似准则数——广义雷诺数,可以应用于工程上的简化计算。     

Study on the slurrying and rheological properties of coal–oilfield wastewater–slurry

In this study, oilfield wastewater (OWW) was used to prepare coal–oilfield wastewater–slurry (COWS), and the apparent viscosity, solid concentration, and rheological curve were studied. Compared with original coal–water–slurry (CWS), the maximum solid concentration of COWS increased, and the viscosity decreased; therefore, the slurrying ability of the coal slurry was improved with the use of OWW. However, although the oil in OWW promoted the slurrying ability of the coal slurry, its effectiveness was insufficient, and a chemical additive was still needed to obtain a coal slurry with enhanced slurrying ability. Both COWS and CWS exhibited shear-thinning behavior, and the rheological index value of COWS was lower, which indicated that pseudoplasticity of COWS was more obvious, and OWW improved the rheological properties of coal slurry.     

CWS-II系列水煤浆燃烧器的研制

水煤浆作为一种有前途的煤基流体燃料,有着极为广泛的应用前景。“六五”期间开发的CWS-I系列工业炉窑水煤浆燃烧器在水煤浆的示范应用工程中,取得了一系列突破,但也存在磨损严重、寿命短等缺陷,从而限制了水煤浆技术在工业领域的进一步推广和应用。在分析了CWS-I系列水煤浆燃烧器存在主要问题的基础上,研制开发了CWS-II系列水煤浆专用燃烧器。     

废液水煤浆和精煤水煤浆煤灰熔融特性试验研究

对取自2台水煤浆锅炉3对各具代表性灰的熔融温度和熔融过程动态特性进行了深入研究。发现废液水煤浆中因含有Na2SO4、NaOH以及NaCl等无机成份,其煤灰熔融特性与精煤水煤浆和制浆原煤相比,更具独特性。     

水煤浆锅炉着火燃烧的影响因素分析

通过冷热态试验研究与数值模拟相结合的方法,分析了加入水煤浆雾矩前后对流场的影响以及水煤浆雾矩在冷热态流场中的差别,得出影响烟气回流形成的3个因素及其重要性:高温烟气受热膨胀以及水煤浆颗粒化学反应导致水煤浆雾矩刚性锐减,由中心向壁面扩散是回流形成的主要因素;水煤浆雾矩的高速射流对回流区形状产生重要影响;旋流燃烧器的旋转射流对回流的影响可以忽略不计.     

Study of pyrolysis of brown coal and gasification of coal‐water slurry using the ReaxFF reactive force field

Based on the Wender coal model, the processes of brown coal pyrolysis and coal‐water slurry (CWS) gasification were studied by molecular dynamics simulations with the ReaxFF reactive force field. To examine the pyrolysis/gasification process and the initiation mechanism of brown coal and its CWS, some large‐scale reactive systems containing different numbers of brown coal and water were built in this work. A relatively high simulation temperature, which was proven reasonable in other studies, was used to control the simulation within an acceptable period of time. The products and the change of potential energy of the systems were analyzed. The related initial reaction mechanisms and factors were discussed. It was found that the pyrolysis of brown coal began with the rupture of bridge bonds, closely followed by the separation of some functional groups such as carboxyl, methoxyl, and methyl. Then, gas products were generated from the reactions between small intermediate structures. Some mechanisms of CO and H₂ generation were discussed in the article. It was observed that temperature significantly enhanced the reactions in the brown coal pyrolysis process and the yields of gas products. For the gasification of CWS, it was observed that the reaction started from the pyrolysis of coal, and then water reacted with the fragments. The effects of temperature and mass fraction were taken into consideration. It was found that gas products were hardly generated and the consumption of water was relatively less at low temperatures and that rising temperature could significantly enhance gas yield and water consumption. There was an inflection point in the curve of water consumption when the temperature is greater than 3000 K. The mass fraction could not affect the gasification process as great as temperature. However, an appropriate amount of water could enhance the yield of gas products and the CWS with 70% mass fraction could provide enough water for H₂ and CO generation. Some of the important reactions and intermediate structures agreed with other experimental data from the literature.     

水煤浆与煤粉燃烧脱硫比较

以煤代油是能源工业的发展方向。作为新型代油燃料,水煤浆有广阔的应用前景。从硫析出特点、脱硫影响因素（温度、Ｃａ／Ｓ比）以及烟尘排放等方面,研究了水煤浆燃烧脱硫与煤粉燃烧脱硫的异同。试验结果表明水煤浆燃烧脱硫优于煤粉,是值得推广的脱硫技术。     

Conversion of brown coal in supercritical water without and with addition of oxygen at continuous supply of coal-water slurry

A study of conversion of organic matter of brown coal in supercritical water (SCW) at 30 MPa, 400−760 °C and continuous supply of coal-water slurry (CWS) into a tubular reactor is presented. It was found that 48−63% (depending on the SCW temperature) of coal organic matter (COM) is ejected from CWS coal particles as liquid and gaseous products when they move through the reactor. We termed this stage of SCW conversion as dynamic conversion (DC) of coal. It turns out that the particles which underwent the DC stage did not aggregate in the reactor during static conversion (SC) within a coal layer due to continuous pumping through this layer. The experimental data on the composition of DC and SC products, degree of coal conversion, and the data on the degree of combustion of carbon in the presence of oxygen are given.     

水煤浆锅炉的能效分析

通过定量和定性计算分析水煤浆水分、磨煤电耗、锅炉运行热效率以及锅炉运行电耗对锅炉能效的影响,并与链条炉排锅炉和煤粉锅炉比较,指出水煤浆替代重油燃烧虽可取得明显的经济效益,但在能效方面却不及燃烧制浆原料煤的链条炉排锅炉或煤粉锅炉。