350 MW电站燃煤锅炉NOx反应特性研究

对350 MW电站四角切圆燃煤锅炉的NOx反应特性进行了试验和数值模拟.结果表明:燃烧器氧的体积分数从3%增大到5%,NOx排放体积分数从392×10-6上升到535×10-6(氧占6%),上升幅度为33.8%.出口氧量(体积分数)为4%时,锅炉的飞灰含碳量最小,燃烧效率最高.随着氧量的增大,炉膛中心温度、炉膛截面平均温度和炉膛截面最高温度等沿高度的分布有减小的趋势,氧量从3%增大到5%,炉膛中心火焰温度的最大减小幅度为180℃.而随着氧量的增大,炉膛中心NOx体积分数、炉膛截面平均NOx体积分数和炉膛截面最大NOx体积分数等沿高度的分布有增大的趋势.炉膛截面最高温度和最大NOx体积分数沿高度的分布出现在燃烧器区域.截面平均温度和截面平均NOx体积分数沿高度分布的最大值出现在燃烧器上方5~10 m处.燃烧器区域炉膛横截面上NOx最大值出现在旋转火焰的环形区域,中心和四周的NOx体积分数较小,炉膛纵截面上的NOx最大值出现在燃烧器组喷口附近.燃煤锅炉的NOx主要在燃烧器区域生成,燃烧器区域的NOx生成速率是燃尽区域的3~5倍.     

350MW超临界四角切圆锅炉燃烧数值模拟

为研究350 MW超临界热电联产四角切圆煤粉锅炉的炉内燃烧问题,基于Fluent6.3模拟软件,分析了炉内的温度和组分分布特性.结果表明:BMCR工况下温度在炉膛燃烧器区横截面上,低温区出现在炉膛中心,在炉壁附近出现局部高温.在炉膛中心纵截面,沿高度、温度呈先上升后下降分布,出口温度为1 138.11 K;炉内O2组分沿高度上升,CO组分先上升后下降,CO2组分先下降后上升.研究结果为超临界锅炉运行监测提供了可靠的理论依据.     

电站锅炉中煤粉燃烧的数值模拟与操作参数的优化

模拟了四角切圆锅炉中煤粉的燃烧过程 ,考虑了三种不同工况 .其一是改变二次风的分配方式 (包括正宝塔、腰鼓以及均等配风 ) ;其二是在水冷壁敷设卫燃带 ;最后是改变燃烧器的上下角度与燃烧器的排列顺序 .计算结果表明 :1#、3#角煤粉的着火距离较 2 #、4 #角长 ,这一结论与生产实践中所观察到的现象一致 ;与均等配风相比较 ,正宝塔与腰鼓配风有利于煤粉的着火 ,但不利于提高屏入口处的烟气温度 ;炉膛内敷设卫燃带显著提高烟气的温度 .     

锅炉炉膛结渣问题的研究攻关

针对一台130t/h切向燃烧锅炉炉膛出现的结渣问题,提出一种可以消除结渣的燃烧器结构和燃烧器配风方式。数值计算结果表明,改造后的燃烧器,锅炉炉内实际切圆直径减小,炉膛温度水平降低,上二次风喷口附近水冷壁壁面O2浓度增加,都有利于抑制和消除炉膛的结渣。改造后的炉膛结渣基本消除,锅炉高负荷运行稳定性提高,数值计算结果与现场实测数据基本吻合。     

浓淡煤粉燃烧器双通道速度差对NOx排放的影响

对350 MW电站四角切圆煤粉锅炉燃烧过程和煤粉燃烧器气固两相流的数值计算表明,常规浓淡煤粉燃烧器的双通道速度差为6～9 m·s-1,因此,提出了等速型浓淡煤粉燃烧器的概念.等速型浓淡煤粉燃烧器比常规直流煤粉燃烧器可减少21.8%的NOx排放,比常规浓淡煤粉燃烧器也可降低11.3%的NOx排放.     

330MW四角切圆锅炉低NO_x优化改造数值模拟

针对某电厂330MW四角切圆锅炉NOx排放质量浓度高、炉内结渣严重的问题,提出基于多空气分级低氮燃烧技术的燃烧器改造方案,运用FLUENT软件对改造前后锅炉燃烧状况进行数值模拟.分析计算和试验数据得出:改造后,浓相一次风反切对炉内燃烧有一定影响,煤粉气流对水冷壁冲刷减弱,结渣现象明显改善;煤粉着火稳燃得到强化,主燃区CO质量浓度增大,炉内还原性气氛增强;燃尽区下部形成的NOx还原区对降低NOx排放质量浓度有积极作用;炉内最高温度下降80℃左右,NOx排放质量浓度降幅达47%左右.     

煤粉孔隙率对四角切圆燃煤锅炉飞灰含碳量及结焦特性的影响

研究煤粉颗粒孔隙率对1 000 MW机组燃煤锅炉飞灰含碳量及结焦特性的影响。选定了25℃、75℃、110℃这三个干燥温度对煤粉进行干燥,测试了煤粉颗粒的水分和孔隙率。采用测试得出的孔隙率范围,利用FLUENT软件对该台四角切圆燃煤锅炉炉内燃烧进行了三维稳态数值模拟,其中,模拟焦炭的燃烧采用了intrinsic模型。研究结果表明:(1)煤粉颗粒的孔隙率、比表面积和孔径都随着煤粉加热温度的升高而增大;(2)煤粉颗粒孔隙率越大,炉膛火焰中心位置越低,燃尽风区域的温度也越低;(3)煤粉颗粒孔隙率越大,煤粉颗粒的碰壁率和炉膛出口的飞灰含碳量都会越小;(4)煤粉颗粒孔隙率越大,水冷壁越不易结焦。研究结果为燃煤锅炉运行实践、设计以及改造提供了依据。     

超超临界锅炉燃烧配风优化的三维数值模拟

建立了带二次风道的660 MW超超临界墙式切圆锅炉的三维数理模型,采用Realizable k-ε双方程湍流模型模拟气相湍流流动,采用P-1辐射模型来描述炉内辐射换热,采用混合分数/概率密度函数模型模拟气相湍流燃烧.研究了锅炉二次风风门挡板的阻力特性,并探究了附加燃尽风门挡板开度对660 MW墙式切圆锅炉燃烧与污染物排放特性的影响.结果表明:附加燃尽风风量与其风门开度阻力系数有关,当风门开度小于50%时,附加燃尽风风门阻力系数曲线斜率大幅增加,风量随开度变化的幅度增大;随着附加燃尽风门挡板开度增加,NOx浓度降低,但在炉膛上部煤粉发生二次燃烧,引起屏底烟气温度升高.     

300MW双炉膛锅炉中煤粉颗粒的运动轨迹

对某发电厂300MW单炉体双炉膛直流锅炉的煤粉颗粒运动轨迹进行了数值模拟研究,结果表明：小煤粉颗粒的运动轨迹与炉内旋转气流基本一致,而中、大煤粉颗粒因气流对其的作用力不足以提供做旋转运动的向心力,做在热角区域气流急剧转弯时撞击在水冷壁上;由此分析了该锅炉烟气侧水冷壁高温腐蚀的某些原因,提出了发行方案,模拟结果显示：降低一次风喷口高度、加宽喷口宽度、采用水平浓谈风煤粉燃烧器,可以提高一次风射流的刚性,避免煤粉颗粒撞击在热角区域的水冷壁上,从而减少高温腐蚀的发生,改造后的性能测试结果表明,改造方案切实可行,取得了良好的运行佳绩。     

电厂天然气锅炉富氧燃烧数值模拟

对传统燃烧方式下和应用富氧燃烧技术(O2/CO2燃烧技术)时电厂天然气锅炉内的燃烧特性进行数值模拟研究.结果表明随着氧气浓度的增大,整个炉膛的高温区分布趋于集中,烟气温度增加,火焰分布更为集中,充满度也越来越差.当氧气浓度为25%时,炉膛内的温度分布和烟气辐射特性与传统燃烧方式下最接近.当氧气浓度由21%上升到40%时,炉膛内烟气温度得到较大幅度的提高,燃烧器所在截面温度上升300 K以上,火焰充满度变差.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with