燃煤锅炉-外文翻译-外文文献-英文文献-中英翻译毕业论文.doc
《燃煤锅炉-外文翻译-外文文献-英文文献-中英翻译毕业论文.doc》由会员分享,可在线阅读,更多相关《燃煤锅炉-外文翻译-外文文献-英文文献-中英翻译毕业论文.doc(13页珍藏版)》请在咨信网上搜索。
1、 外文出处: A. A. Shatil, N. S. K. A. A. S., & V. Kudryavtsev, A. (2008). Controllingthe furnace process in coal-fired boilers. Thermal Engineering, 55, 1, 72-77. Controlling the Furnace Process in Coal-Fired BoilersThe unstable trends that exist in the market of fuel supplied to thermal power plants and
2、 the situations in which the parameters of their operation need to be changed (or preserved), as well as the tendency toward the economical and environmental requirements placed on them becoming more stringent, are factors that make the problem of controlling the combustion and heat transfer process
3、es in furnace devices very urgent. The solution to this problem has two aspects. The first involves development of a combustion technology and,accordingly, the design of a furnace device when new installations are designed. The second involves modernization of already existing equipment. In both cas
4、es,the technical solutions being adopted must be properly substantiated with the use of both experimental and calculationstudies.The experience Central Boiler-Turbine Institute Research and Production Association (TsKTI) and ZiO specialists gained from operation of boilers and experimental investiga
5、tions they carried out on models allowed them to propose several new designs of multifuel and maneuverablein other words, controllablefurnace devices that had been put in operation at power stations for several years. Along with this, an approximate zero-one-dimensional, zonewise calculation model o
6、f the furnace process in boilers had been developed at the TsKTI, which allowed TsKTI specialists to carry out engineering calculations of the main parameters of this process and calculate studies of furnaces employing different technologies of firing and combustion modes .Naturally, furnace process
7、 adjustment methods like changing the air excess factor, stack gas recirculation fraction, and distribution of fuel and air among the tiers of burners, as well as other operations written in the boiler operational chart, are used during boiler operation.However, the effect they have on the process i
8、s limited in nature. On the other hand, control of the furnace process in a boiler implies the possibility of making substantial changes in the conditions under which the combustion and heat transfer proceed in order to considerably expand the range of loads, minimize heat losses, reduce the extent
9、to which the furnace is contaminated with slag, decrease the emissions of harmful substances, and shift to another fuel. Such a control can be obtained by making use of the following three main factors:(i) the flows of oxidizer and gases being set to move in the flame in a desired aerodynamic manner
10、;(ii) the method used to supply fuel into the furnace and the place at which it is admitted thereto;(iii) the fineness to which the fuel is milled.The latter case implies that a flame-bed method is used along with the flame method for combusting fuel.The bed combustion method can be implemented in t
11、hree design versions: mechanical grates with a dense bed, fluidized-bed furnaces, and spouted-bed furnaces.As will be shown below, the first factor can be made to work by setting up bulky vortices transferring large volumes of air and combustion products across and along the furnace device. If fuel
12、is fired in a flame, the optimal method of feeding it to the furnace is to admit it to the zones near the centers of circulating vortices, a situation especially typical of highly intense furnace devices. The combustion process in these zones features a low air excess factor ( 1) and a long local ti
13、me for which the components dwell in them, factors that help make the combustion process more stable and reduce the emission of nitrogen oxides .Also important for the control of a furnace process when solid fuel is fired is the fineness to which it is milled; if we wish to minimize incomplete combu
14、stion, the degree to which fuel is milled should be harmonized with the location at which the fuel is admitted into the furnace and the method for supplying it there, for the occurrence of unburned carbon may be due not only to incomplete combustion of large-size fuel fractions, but also due to fine
15、 ones failing to ignite (especially when the content of volatiles Vdaf 20%).Owing to the possibility of pictorially demonstrating the motion of flows, furnace aerodynamics is attracting a great deal of attention of researchers and designers who develop and improve furnace devices. At the same time,
16、furnace aerodynamics lies at the heart of mixing (mass transfer), a process the quantitative parameters of which can be estimated only indirectly or by special measurements. The quality with which components are mixed in the furnace chamber proper depends on the number, layout, and momenta of the je
17、ts flowing out from individual burners or nozzles, as well as on their interaction with the flow of flue gases, with one another, or with the wall.It was suggested that the gas-jet throw distance be used as a parameter determining the degree to which fuel is mixed with air in the gas burner channel.
18、 Such an approach to estimating how efficient the mixing is may to a certain degree be used in analyzing the furnace as a mixing apparatus. Obviously, the greater the jet length (and its momentum), the longer the time during which the velocity gradient it creates in the furnace will persist there, a
19、 parameter that determines how completely the flows are mixed in it. Note that the higher the degree to which a jet is turbulized at the outlet from a nozzle or burner, the shorter the distance which it covers, and, accordingly, the less completely the components are mixed in the furnace volume. Onc
20、e through burners have advantages over swirl ones in this respect.It is was proposed that the extent to which once through jets are mixed as they penetrate with velocity w2 and density 2 into a transverse (drift) flow moving with velocity w1 and having density 1 be correlated with the relative jet t
21、hrow distance in the following wayWhere ks is a proportionality factor that depends on the “pitch” between the jet axes (ks= 1.51.8).The results of an experimental investigation inwhich the mixing of gas with air in a burner and then in a furnace was studied using the incompleteness of mixing as a p
22、arameter are reported in 5.A round once through jet is intensively mixed with the surrounding medium in a furnace within its initial section, where the flow velocity at the jet axis is still equal to the velocity w2 at the nozzle orifice of radius r0.The velocity of the jet blown into the furnace dr
23、ops very rapidly beyond the confines of the initial section, and the axis it has in the case of wall-mounted burners bends toward the outlet from the furnace.One may consider that there are three theoretical models for analyzing the mixing of jets with flowrate G2 that enter into a stream with flowr
24、ate G1. The first model is for the case when jets flow into a “free” space (G1= 0),the second model is for the case when jets flow into a transverse (drift) current with flowrate G1G2,and the third model is for the case when jets flow into a drift stream with flowrate G1G2. The second model represen
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- 燃煤 锅炉 外文 翻译 文献 英文 毕业论文
1、咨信平台为文档C2C交易模式,即用户上传的文档直接被用户下载,收益归上传人(含作者)所有;本站仅是提供信息存储空间和展示预览,仅对用户上传内容的表现方式做保护处理,对上载内容不做任何修改或编辑。所展示的作品文档包括内容和图片全部来源于网络用户和作者上传投稿,我们不确定上传用户享有完全著作权,根据《信息网络传播权保护条例》,如果侵犯了您的版权、权益或隐私,请联系我们,核实后会尽快下架及时删除,并可随时和客服了解处理情况,尊重保护知识产权我们共同努力。
2、文档的总页数、文档格式和文档大小以系统显示为准(内容中显示的页数不一定正确),网站客服只以系统显示的页数、文件格式、文档大小作为仲裁依据,平台无法对文档的真实性、完整性、权威性、准确性、专业性及其观点立场做任何保证或承诺,下载前须认真查看,确认无误后再购买,务必慎重购买;若有违法违纪将进行移交司法处理,若涉侵权平台将进行基本处罚并下架。
3、本站所有内容均由用户上传,付费前请自行鉴别,如您付费,意味着您已接受本站规则且自行承担风险,本站不进行额外附加服务,虚拟产品一经售出概不退款(未进行购买下载可退充值款),文档一经付费(服务费)、不意味着购买了该文档的版权,仅供个人/单位学习、研究之用,不得用于商业用途,未经授权,严禁复制、发行、汇编、翻译或者网络传播等,侵权必究。
4、如你看到网页展示的文档有www.zixin.com.cn水印,是因预览和防盗链等技术需要对页面进行转换压缩成图而已,我们并不对上传的文档进行任何编辑或修改,文档下载后都不会有水印标识(原文档上传前个别存留的除外),下载后原文更清晰;试题试卷类文档,如果标题没有明确说明有答案则都视为没有答案,请知晓;PPT和DOC文档可被视为“模板”,允许上传人保留章节、目录结构的情况下删减部份的内容;PDF文档不管是原文档转换或图片扫描而得,本站不作要求视为允许,下载前自行私信或留言给上传者【胜****】。
5、本文档所展示的图片、画像、字体、音乐的版权可能需版权方额外授权,请谨慎使用;网站提供的党政主题相关内容(国旗、国徽、党徽--等)目的在于配合国家政策宣传,仅限个人学习分享使用,禁止用于任何广告和商用目的。
6、文档遇到问题,请及时私信或留言给本站上传会员【胜****】,需本站解决可联系【 微信客服】、【 QQ客服】,若有其他问题请点击或扫码反馈【 服务填表】;文档侵犯商业秘密、侵犯著作权、侵犯人身权等,请点击“【 版权申诉】”(推荐),意见反馈和侵权处理邮箱:1219186828@qq.com;也可以拔打客服电话:4008-655-100;投诉/维权电话:4009-655-100。