用于燃煤电厂的低温省煤器前烟道流动及磨损特性

以低温省煤器及其管道为研究对象,采用数值模拟方法,对低温省煤器及其管道流动及磨损特性进行分析,采用添加导流板的方式对流场进行优化以降低磨损量。低温省煤器前方圆节的布置导致流场紊乱,低温省煤器入口截面速度分布均匀性较差,管束磨损区域与高速区相对应,冲蚀磨损主要集中在中心区域,第一排管束迎风区磨损量最大,后排管束磨损量依次降低;对方圆节内置导流板进行优化后,低温省煤器前流场速度标准偏差由34.9降低至15.2,均匀性提高,管束的最大冲蚀磨损量降低两个数量级,磨损程度大幅度降低,保障了低温省煤器的安全经济运行,为低温省煤器及其管道的优化设计及运行提供了理论参考与数据支持。     

锅炉省煤器磨损机理及防磨措施

从理论上分析了电站锅炉省煤器的磨损机理，解释了省煤器管子的磨损特征及主要的影响因素，分析主要影响因素后认为烟气速度对受热面的磨损起决定作用，并总结了造成烟气流速大于设计值的3点因素，提出并论证了减轻和防止省煤器磨损的6项措施和建议．     

锅炉省煤器磨损机理及防磨措施

从理论上分析了电站锅炉省煤器的磨损机理 ,解释了省煤器管子的磨损特征及主要的影响因素 ,分析主要影响因素后认为烟气速度对受热面的磨损起决定作用 ,并总结了造成烟气流速大于设计值的 3点因素 ,提出并论证了减轻和防止省煤器磨损的 6项措施和建议 .     

膜式省煤器磨损机理的探讨

通过某电厂光管式改造成膜式省煤器的运行实践和流场实验结果，建立了膜片间烟气的速度场和飞灰场分布曲线及函数关系式，阐述了膜式省煤器管外烟气流场的特点，分析，论证了采用传统方法计算膜式省煤器磨损量使用寿命的缺陷；提出了较切合实际的建议，对今后膜式省煤器的设计及应用，具有参考价值。     

锅炉采用膜式省煤器方案的研究

膜式省煤器在国内的应用刚刚起步,目前还存在不少有待研究解决的问题.本文简要地阐明了影响锅炉省煤器磨损的因素,介绍了膜式省煤器的特点,特别是根据国内外膜式受热面的研究结果和使用情况,提出了膜式省煤器设计和制造的若干建议,并据此针对一台220t/h锅炉进行了膜式省煤器方案设计,最后将设计计算的结果与原光管式省煤器进行了技术经济比较,得到了具有实际意义的结论.     

省煤器泄漏分析

针对对某电厂2号炉高温省煤器爆管.通过现场调查、对管材进行分析等工作,综合分析认为引起高温省煤器管爆漏的原因是磨损所致.产生磨损的原因与省煤器管局部烟气速度增高和局部的飞灰集中以及煤粉成份、细度有关.     

省煤器错排管束飞灰磨损情况的预测分析

针对电厂锅炉省煤器管等对流受热面的飞灰磨损问题,建立错列管束的物理模型,以贴体网格进行数值模拟计算,得省煤器管近壁处灰颗粒的流速分布,以预测省煤器管的磨损情况或进行磨损加速试验。本方法可用于电厂预测省煤器内部管束的磨损;在实施防磨时,直观地预测防磨效果,进行防磨方案的选优。     

膜式省煤器传热特性研究

以通辽发电总厂２号炉改造后膜式省煤器为例，对目前国内外用于膜式省煤器设计计算的若干公式计算的准确性进行了分析比较。并根据模化理论，对膜式省煤器进行了试验台试验，并对照工业性试验结果，提出了一种较为实用的灰污系数选取方法和这种典型膜式省煤器的放热特性关联式。     

SG400/140-50410型锅炉省煤器改造

省煤器区域烟道流通面积偏小 ,烟气流速高 ,加之燃用煤质含灰量高 ,所以省煤器磨损较快。对 #4炉省煤器改造 ,改造选用螺旋肋片管省煤器替换原光管省煤器 ,强化省煤器管外部传热。在保证传热量不变的情况下 ,减少管排数量 ,增大烟气流通面积 ,以降低烟气流速 ,减轻受热面磨损。肋片在管外还具有防磨作用 :引导气流均匀流动 ,防止飞灰直接冲刷管壁     

应用于低压省煤器的H型鳍片管传热分析

锅炉排烟温度过高会造成热损失,增设低压省煤器对于降低电厂排烟温度,提高电厂热经济性,保护空气预热器的安全运行具有重要意义。H型鳍片管是一种广泛应用于低压省煤器的换热元件。本文以一种H型鳍片管为例,通过数值模拟对其传热过程进行了分析,获得了H型鳍片管翅片侧表面传热系数和流动阻力随烟气流速和鳍片节距的变化规律。     

Performance of cemented coal gangue backfill

Possibility of cemented gangue backfill was studied with gangue of Suncun Coal Mine, Xinwen Coal Group, Shandong, and fly ash of nearby thermal power plant, in order to treat enormous coal gangue on a large scale and to recovery safety coal pillars. The results indicate that coal gangue is not an ideal aggregate for pipeline gravity flow backfill, but such disadvantages of gangue as bad fluidity and serious pipe wear can be overcome by addition of fly ash. It is approved that quality indexes such as strength and dewatering ratio and piping feature of slurry can satisfy requirement of cemented backfill if mass ratio of cement to fly ash to gangue is 1：4：15 and mass fraction of solid materials reaches 72%-75%. Harden mechanism suggests that the cemented gangue fill has a higher middle and long term comprehensive strength.     

Paste-like self-flowing transportation backfilling technology based on coal gangue

A paste-like self-flowing pipeline transportation backfilling technology with coal gangue as aggregate is proposed to remove the potential damage caused by coal gangue piles. As well, the difficult problems of recovering high quality safety coal pillars and deep mining of the Suncun Coal Mine (SCM), Xinwen Coal Group, Shandong are resolved. The physical-chemical properties of coal gangue, optimized proportion of materials, backfilling system and craft in the SCM were studied in the laboratory and then an industrial test was carried out on high quality coal pillars under a town. The results show that finely crushed kaolinized and fresh gangue with granularity less than 5 mm can be used as aggregate with fly ash to replace part of the cement and a compos-ite water reducer as an additive, accounting for 1.0%-1.5% of the total amount of cement and fly ash. The recommended proportion is I(cement):4(fly ash): 15(coal gangue), with a mass fraction of 72%-75%, theological paste-like properties and a strength of more than 0.7 MPa at 7 d. The sequence of adding cement, fly ash, water reducer and then coal gangue ensures that the suspended state of the slurry, reducing the wear and jam of pipelines. The working face is advancing continuously by the alternating craft of building block walls with coal gangue and backfilling mined-out gobs with paste-like slurry. The recovery rate is as high as 90% with a backfilling cost of 36.9 Yuan/t, good utilization of coal gangue and no subsidence on the surface. This technology provides a good theoretical basis and application experience for coal mines, cement backfilling with paste-like slurry.     

Parametric study of electrostatic separation of South African fine coal

The fact that water requirements are a major problem for present and future developments in material beneficiation, and the construction of a new power plant in South Africa, forms the basis for the utilization of a Rotary Triboelectrostatic Separator (RTS) for beneficiation of South African pulverized coal. The cleaning potential of Majuba and Koorfontein coal was first evaluated using kinetic froth flotation tests on the -177μm coal fraction. The RTS tests were conducted under varied process parameters. Parameters such as applied separating voltage, air injection velocity, particle feed rate and splitter position were investigated. Two stage separation results show that the RTS reduced Majuba coal initially containing about 30% ash to a clean product of 14.30%, or 19.46%, ash at a combustible recovery of 15.10%, or 53.02%, respectively. Similar separation performance was also achieved with the Koorfontein coal. The mineral and organic compositions in the feed, after single stage and after the second stage separations were characterized using X-ray diffraction analysis. The results show a better separation for the second stage coal products.     

Direct-impact of sieving coal and gangue

Gangue from underground separation of coal can directly be used for filling mined out areas, saving transport capacity and reducing the amount of waste polluting the environment above the ground. We introduced a structure and operating principle of an underground direct-impact sieving device by which a separation experiment was carried out. By means of high speed conveyer belts, coal and gangue impacted the breaking board at high speeds ranging from 6 to 14 m/s. Given the differences of hardness between coal and gangue, after selective crushing, the gangue with the higher hardness was crushed less and coal with lower hardness crushed more, which could be separated by a 50 mm sieving plate. The material above the sieving plate was disposed of as gangue and the material below as coal. The results indicate that the crush ratio below the 50 mm sieving plate increases linearly with an increase in impact velocity and decays exponentially with an increase in hardness. Employing this equipment to separate coal and gangue, the hardness of coal f should be <2. This separation device provides relatively good effect in separating coal and gangue with a relatively wide difference of hardness.     

两种煤配煤降低淮南煤高灰熔融性温度的研究

通过两两配煤的方法,对高灰熔融性淮南煤与4种灰熔融性温度较低煤进行配加,可以显著降低淮南煤的高灰熔融性温度,基本符合Texaco气化炉液态排渣要求。配煤灰熔融性温度的变化不是两种单煤灰熔融性温度简单的加和关系,而是非线形的关系,这与灰熔融过程中结晶矿物形成的种类不同有关。通过X-衍射分析,初步探讨灰熔融性机理。     

成灰温度对生物质与煤混烧中灰熔融性的影响

燃料的灰熔融性对受热面的结渣起着关键作用.生物质与煤的灰熔融性测定借用煤的测定标准,难以真实评判灰的熔融特性.在不同成灰温度下,利用HR-3C灰熔融性测定仪,以稻秆、白杨木屑、稻壳和煤在不同配比下混合燃烧的灰分作为研究对象,研究了成灰温度对生物质与煤混合燃烧的熔融特性.研究表明:不同的成灰温度对生物质与煤混合燃料的灰熔融性特征参数有着明显的影响,根据生物质中无机元素的特性和实际锅炉燃烧情况,对生物质与煤混燃成灰方法,借用ASTM E1755-01规定的低温成灰标准更能够准确反应其灰的熔融性.     

成灰温度对生物质与煤混烧中灰熔融性的影响

燃料的灰熔融性对受热面的结渣起着关键作用.生物质与煤的灰熔融性测定借用煤的测定标准,难以真实评判灰的熔融特性.在不同成灰温度下,利用HR-3C灰熔融性测定仪,以稻秆、白杨木屑、稻壳和煤在不同配比下混合燃烧的灰分作为研究对象,研究了成灰温度对生物质与煤混合燃烧的熔融特性.研究表明：不同的成灰温度对生物质与煤混合燃料的灰熔融性特征参数有着明显的影响,根据生物质中无机元素的特性和实际锅炉燃烧情况,对生物质与煤混燃成灰方法,借用ASTM E1755-01规定的低温成灰标准更能够准确反应其灰的熔融性.     

新疆石煤料团流化床焙烧提钒试验研究

在一台小型流化床燃烧试验台上对新疆石煤料团进行了焙烧特性的试验,着重考察了焙烧温度、焙烧时间、流化风速、添加剂种类对焙烧成球率的影响,并对飞灰、底渣、床料进行收集采样,利用水浸、质量分数为2%的Na2CO3溶液、6%的H2SO4溶液、10%的H2SO4溶液对各种样品浸取提钒,研究了焙烧温度、焙烧时间、浸取方式对转浸率的影响.结果表明:采用水泥为添加剂,温度为930℃,焙烧时间为90min,采用质量分数为10%的H2SO4溶液酸浸,可得较高焙烧成球率和转浸率,钒总回收率约为55.1%,同时可有效回收石煤热能,用于产汽发电.     

Lowering ash slagging and fouling tendency of high-alkali coal by hydrothermal pretreatment

High-alkali species in coal are notorious for causing ash slagging and fouling incidents. In this paper, four high-alkali coals were individually subject to hydrothermal pretreatment(HTP), within a batch-type autoclave at 300 °C for 1 h, and the treated coals were analyzed, along with the oxygen-containing functional groups determined by Fourier transform infrared spectrometer(FT-IR). Then the alkali species and other components in the coal ash were quantified by X-ray fluorescence(XRF) for evaluating the ash slagging and fouling tendency. Apart from this, FactSage was adopted to simulate the occurrence and transformation of alkali species during coal thermal conversion ending at various temperatures. The findings indicate that the treated coals are superior to the parent ones in terms of certain remarkable changes via HTP. The moisture, oxygen and sulfur of the hydrothermally treated coals decline obviously, while the calorific value rises sharply. HTP could reduce the alkali species to less than 2%(%, by weight, equivalent to Na_2 O in dry ash), with a maximum removal ratio of 88.9%, lowering the ash slagging and fouling tendency. The proposed mechanism of HTP was that the alkali species in coal matrix became released due to the breakage of the coal functional groups and micropores during HTP.     

添加剂对高碱煤灰渣流动特性及钠捕获效率的影响

为了给液态排渣锅炉安全燃烧准东高碱煤提供理论依据,在水平管式炉上利用刚玉斜坡对添加不同质量分数 SiO₂、CaO、Fe₂O₃和MgO的准东煤灰渣在空气气氛下的流动性能进行研究. 利用XRF技术对煤灰渣的钠质量分数进行分析,并通过钠捕获效率来表征煤灰渣的固钠效果. 研究表明：SiO₂和Fe₂O₃能够促进准东煤灰熔融.当SiO₂的质量分数为10% 时,煤灰渣由结晶渣逐渐转变为玻璃体渣,流动性能大大提高;而CaO和MgO则会抑制煤灰熔融,导致流动性能降低. 随着SiO₂添加比例的增加,灰渣对钠的捕获效率逐渐升高,当SiO₂的质量分数达10%时,钠捕获效率由原先的23%上升至30%;而随着Fe₂O₃添加比例的增加,钠捕获效率缓慢降低. 因此,当SiO₂的质量分数为10%时即可有效改善煤灰渣的流动性能,又能提高钠的捕获效率.