大型电厂2×1000MW机组间接空冷系统环境风影响分析

间接空冷系统作为一种有效的节水型火力发电冷却技术、是我国西北等缺水地区新建采用的主要电厂冷却系统形式之一.间接空冷系统在环境风特别是高温大风条件下的散热能力及变化规律值得深入研究.利用计算流体力学方法,对一个2×1 000MW大型电厂间接空冷系统实例进行了计算.通过对空冷塔及周围速度场温度等流场细节的分析,从经济型和安全性两个方面分析了系统散热能力的变化规律.结果表明,小风条件下间接空冷系统散热能力较好,背压波动幅度很小;大风条件下散热能力迅速恶化,高温大风条件下机组难以满发.     

直接空冷系统汽轮机运行背压的一种计算方法

直接空冷技术已经广泛应用在缺水地区的火电厂中,但环境风对空气冷凝器的安全稳定运行有很大影响。设计人员需要对空冷系统进行数值模拟,了解风场对空冷系统换热性能的影响程度。目前常规的空冷电厂数值模拟方法和工程计算软件只能给出空冷换热器的换热效率,无法直接计算出在环境风作用下的汽轮机运行背压。采用汽轮机乏汽管道内部流动换热与空冷系统所处风场的内外流场耦合计算方法,能够直接计算出各种环境条件下汽轮机的运行背压,并以某大型空冷电厂为实例进行了数值模拟验证。     

直接空冷机组冬季防冻技术研究

分析了直接空冷机组冬季冻结的主要原因,结合山西部分电厂运行经验与现场试验,从直接空冷系统运行方面提出了若干防冻建议,指出通过在直接空冷散热器表面加装温度测点及空冷百叶窗装置,采用红外成像仪对空冷机组表面进行温度监测,可有效防冻,确保机组的经济运行。     

浅谈直接空冷机组设计背压的选择

直接空冷机组背压的选择是直接空冷机组设计的重要技术问题之一。直接空冷电厂空冷机组设计背压选择,是低是高,不可一概而论。必须充分考虑影响运行背压的多种变化因素,要根据市场经济的要求在空冷系统ITD优化计算时,充分论证煤价的影响,并进行技术、经济比较。以便恰当掌握各种余度,确保空冷机组既安全可靠、经济合理。     

空冷平台提升换热效率装置的监测实验研究

电厂空冷机组的换热效率极易受所处环境风的影响,在其空冷平台下设置智能提升换热效率装置,将空冷平台下方全封闭,通过智能控制系统传感器识别环境风速、风向,根据程序计算由计算机通过执行机构自动完成对风障叶片单元模块的开启,最大限度满足轴流风机进风量,保证热量交换效率。监测加装空冷平台提升换热效率装置对空冷平台换热效率的影响,结果表明在大风条件下,汽轮机运行背压显著降低,稳定在正常背压,在小风条件下,改善了空冷平台周围的流场,背压稍有降低。所得结论空冷平台提升换热效率装置在不同风向下使机组风机平均流量差异不超过设计限额,使风机入口平均温度降低,降低背压,进而使冷凝器换热效率提升,提高发电量及发电的安全性,同时节能减排,大大减少电厂的煤炭消耗,为改善环境风工况下空冷平台性能提高及防风设计提供参考。     

机械通风间冷塔在电厂中的应用

本文以山西新建某2×330MW煤矸石电厂为例,就机械通风间冷塔系统设计特点、运行可靠性进行简单的分析介绍。结果表明在主机采用直接空冷火力发电厂,给水泵汽轮机采用机械通风间冷塔在技术上是可行的,为我国以后主机采用直接空冷发电厂,给水泵汽轮机冷却方式的选择上提供了一条新的选择路径。     

变频装置在电厂直接空冷系统中的应用

介绍了电厂直接空冷系统的原理及组成,阐述了直接空冷系统变频控制功能、设计选型要求、功能实现、应用实例及前景展望等.     

浅谈给水泵误动作切换时引起空冷风机跳闸的防范措施

变频器在电厂生产中起着举足轻重的作用,对于电厂来说空冷凝汽器系统空冷风机的变频器运行状况直接影响着机级的安全性、经济性.通过对几次空冷变频器大面积跳闸的原因进行分析总结,制定并采取了以下防范措施,有效的避免了空冷系统大面积停运恶性事件的发生.使得变频器有效利用率提高,同时也大大提高机组的安全性与经济性.     

大型直接空冷机组设计选型探讨

将不同类型的600MW等级大型的直接空冷机组的设计参数和实际运行的情况进行比较分析,从中总结出直接空冷机组的系统总容量和抗干扰能力进行选择的建议,分析了电厂的空冷机组设计和选型的方法,为电厂选型和设计的招标提供借鉴。     

600MW直接空机组主要技术经济指标分析

直接空冷是空冷技术的发展方向,分析直接空冷机组主要技术经济指标并进行节能降耗研究对提高直接空冷机组运行经济性具有重要意义。以内蒙古某发电有限公司600MW等级直接空冷机组为例,对供电煤耗率、厂用电率、汽轮机热耗、真空度、节水量等5个方面的指标进行了分析,初步指出了影响以上技术经济指标的因素,并结合直接空冷系统的特点提出了初步的防治措施,对提高直接空冷机组运行经济性有一定的指导作用。     

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.     

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     

Journal of Donghua University ( English Edition) Contents of Volume 31

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Brief Introduction to “Journal of Jilin University( Science Edition) ”

<正>"Journal of Jilin University(Science Edition)"is a comprehensive academic journal in the fields of science sponsored by Jilin University and administrated by the Ministry of Education of the Peoples Republic of China.The journal started publication in 1955.The original name at starting publication was"Journal of Natural Science of Northeast People University",which was changed into"Acta Scientiarum Naturalium Universitatis Jilinensis"in 1958 owing to the name change of the university.The present journal name has