第一篇：热能与动力工程专业英语翻译Ch 02 教案
Chapter 2 Boiler
第二章
锅炉
Air heater 空预器 Anchor 支座，固定 Anhydrous ammonia 无水氨 Anthracite 无烟煤 Atomized 雾化 Austenitic 奥氏体钢 Auxialiary 辅助机械 Axis 轴 Bagasse 甘蔗渣 Bare tube 光管 Bark 树皮 Beam 梁，横梁 Bituminous coal 烟煤 Blade 叶片 Blast 鼓风 Blowdown 排污 Boiler 锅炉 Bulk 大块的
Burner zone 燃烧器区域 Butane 丁烷 Calcination 煅烧 Capacity 出力 Carbon steel 碳钢 Cerium 铈 Chromium 铬 床锅炉 Coal char 煤焦
Cogenerator 热点联产机组 Combustion 燃烧
Dwell time 保留时间 Economizer 省煤器 Embrittlement 脆性，脆化
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Commissioning 试运行 Compressor 压缩机、压气机 Condenser 凝汽器 Containment 反应堆安全壳 Convection 对流 Coolant 制冷剂 Coordinated 坐标，定位 Corten低合金耐腐蚀钢 Counterflow 逆流（换热器）Creep strength 蠕变强度 Criterion 标准
Critical pressure 临界压力 Culm 煤屑
Cyclone furnace 旋风炉 Debris 残骸、有机残留物 Decane 癸烷 Decay 分解
Deposited 沉积，沉淀的 Deterioration 恶化 Diesel oil 柴油 Differential 差动，微分 Distillate 馏出物 Distortion 变形
Division wall 分隔墙，双面水冷壁 Drainage 疏水
Circulating fluidized bed CFB 循环流化Drum 汽包 Equalization 均衡，平衡 Erosive 侵蚀的，腐蚀的 Ethane 乙烷 Evaluate 评估，评价 Evaporate 蒸发 Excess air 过量空气 Extended surface 扩展受热面 Fatigue 疲劳 Feedwater 给谁 Ferrite 铁素体 Fin 鳍片，肋片 Flange 法兰 Flue gas 烟气 Fouling 沾污 Furnace 炉膛 Generator 发电机 Geological 地质的 Girth 环形 Govern 控制、调节 Gravity 重力 Header 联箱，集箱 Helical 螺旋状的 Helium 氦
Heterogeneous 不均匀的 Hopper 斗，料斗 Husk 壳，外壳
Hydraulic 水力的，液压的 Ignite 点火 Impurity 杂质 Inert 惰性
Inferior 低级的，劣质的 Ingredients 成分
Ingress进口，入口 In-line 顺列 Inorganic 无机的 Ion 离子 Jurisdiction 权限 Lignite 褐煤 Lime 石灰 Limestone 石灰石 Low alloy 低合金钢 Low-volatile 低挥发分的 Margin 裕量，安全系数 Matrix 矩阵 Membrane 膜 Methane 甲烷 Mill 磨煤机 Molecule 分子 Molten 熔化 Nitric oxide 氮氧化物 Nonpressure 非承压的 Nontoxic 无毒的 Organisms 有机体 Oxidation 氧化 Peat 泥煤
Pendants superheat platen 悬吊式屏式过热器 Pentane 戊烷
Petrochemical 石油化工制品 Petroleum 石油制品
Plasma spray coating 等离子喷涂Platen 屏 Polymer 聚合物 Pores 气孔，小孔 Porosity多空的
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Potassium 钾
Prandtl numbers 普朗特数 Prefabricated 预制的 Premium fuel 优质燃料 Pressure loss 压力损失 Primary air 一次风 Propane 丙烷
Proximate analysis 工业分析 Pulp 纸浆 Pyrites 黄铁矿 Radius 半径，范围 Rare earth element 稀土元素 Recuperator 间壁式换热器 Regenerator 回热器，蓄热器Regulate 控制，调节 Repercussions 反应 Reservoirs 储气罐 Residuale fuel oil 渣油 Resonant 共振 Retract缩回
Reynolds number 雷诺数 Rigid 刚性的，紧密地 Rollers 辊子 Scale 水垢，Seal 密封 Sedimentary 沉积 Serpentine tube 蛇形管 Shale 页岩 Silica 二氧化硅 Silt 淤泥 Single-phase 单相 Skin casing 外护板 Slag 结渣
Slurry 水煤浆 Sodium 钠 Solvents 溶剂 Sootblower 吹灰器 Sour gas 含硫气体 Specification 规格 Stable ignition 稳定着火 Stanton number 斯坦顿数 Saturated 饱和的 Straw 稻草
Steam line blowing 蒸汽管路吹灰 Steams 茎，杆
Stress corrosion 应力腐蚀 Structural formula 结构式 Stud 双头螺栓
Subbituminous 贫煤，次烟煤 Suction 真空，负压 Sulphur 硫 Superheater 过热器 Swamp 沼泽 Sweet gas 无硫气
Switchgear 配电装置，开关装置 Temperature-entropy 温熵图 Tenacious 黏的 Thermodynamics 热力学 Tube bundles 管束 Tubular 管状的 Turbine 汽轮机 Velocity 速度
Vertical spidle mill 中速磨，立轴磨Vessel 容器 Viscosity 黏度
Volumetric expansion 体膨胀
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Vulnerable 易损的，薄弱的 Wear磨损 Welded 焊接 Wingwall屏式凝渣管 Yttrim 釔
Abbreviations AFBC 常压流化床燃烧 AFCO 燃料自动切断 AFWC 给水自动切断 ASME 美国机械工程师协会 ATM 标准大气压 BFP 锅炉给水泵 BUT 按钮 BWC锅炉水浓度 BYP 旁路
CFBB 循环流化床锅炉 MCR 最大连续蒸发量 DAS 数据采集系统
2.1 Introduction
DEH 数字电液系统 DNB 偏离核态沸腾 FDF 送风机 FGD 烟气脱硫
FSSS 炉膛安全检测保护系统 HRB 回热锅炉 IDF 引风机
IGCC 整体煤气化联合循环 LMTD 对数平均温差 MFT 主燃料切断 MUF 锅炉补给水 NWL 正常水位 OFA 火上风，燃尽风 PFBC 增压流化床燃烧 SSC 刮板除渣机 TGA 热重分析仪 UBC 未燃烧 WFGD 湿法烟气脱硫
Boilers use heat to convert water into steam for a variety of applications.Primary among these are electric power generation and industrial process heating.Steam has become a key resource because of its wide availability, advantageous properties and non toxic nature.The steam flow rates and operating conditions can vary dramatically;from 1000lb/h(0.1kg/s)in one process use to more than 10 million lb/h(1260kg/s)in large electric power plant;from about 14.7 psi(1 bar)and 212ºF in some heating applications to more than 4500 psi(310bar)and 1100 ºF(593℃)in advanced cycle power plant.2.1 简介SSC 锅炉利用热量使水转变成蒸汽以进行各种利用。其中主要是发电和工业供热。由于蒸汽具有有利的参数和无毒特性，因此蒸汽作为一种关键的工质（资源）被广泛地应用。蒸汽流量和运行参数的变化很大：从某一过程里1000磅/小时（0.126kg/s）到大型电厂超过10×106
29-4 磅/小时（1260kg/s），压力从一些加热应用的14.7磅/ in2（1.0135bar）212F（100℃）到先进循环电厂的4500磅/ in2（310bar）1100F（593℃）。
Modern boilers can be classified by various criteria.These include end use, firing method, operating pressure, fuel and circulation method.现代锅炉可根据不同的标准分类。这些包括最终用途、燃烧方式、运行压力、燃料和循环方式。
Utility boilers are used primarily to generate electricity in large central power stations.They are designed to optimize overall thermodynamic efficiency at the highest possible availability.A key characteristic of newer units is the use of a reheater section to increase overall cycle efficiency.大型中心电站的电站锅炉主要用来发电。它们经过优化设计，可达到最高的热效率。新机组的关键特性是利用再热器提高整个循环效率。
A variety of additional systems also produce steam for power and process applications.These systems usually take advantage of low cost or free fuels, a combination of power cycles and process, and recovery of waste heat in order to reduce overall costs, examples of these include: 各种附加的系统也产生蒸汽用于发电及其他过程应用。这些系统常常利用廉价或免费燃料，联合动力循环和过程，以及余热回收，以减少总费用。这些例子包括：
Gas turbine combined cycle(CC)use advanced gas turbines with heat recovery steam generator as part of a base cycle to use waste heat recovery and increase thermal efficiency.燃气轮机联合循环（CC）：先进的燃气轮机，将余热锅炉作为基本循环的一部分，以利用余热并提高热效率。
Integrated Gasification Combined Cycle(IGCC)adds a coal gasifier to the CC to reduce fuel cost and minimize airborne emissions.整体煤气化联合循环（IGCC）：在CC基础上增加煤气化炉，以降低燃料费用并将污染排放降到最低。
Pressurized Fluidized-bed Combustion(PFBC)includes higher pressure combustion with gas cleaning and expansion of the combustion products through a gas turbine.增压循环流化床燃烧（PFBC）：在更高压力下燃烧，包括燃气净化，以及燃烧产物膨胀并通过燃气轮机做功。
29-5 Blast furnace hood heat recovery generates steam using the waste heat from a blast furnace.高炉排烟热量回收：利用高炉余热产生蒸汽。
Solar steam generator uses concentrators to collect and concentrate solar radiation and generate steam.太阳能蒸汽发生器：利用集热器收集太阳辐射热产生蒸汽。
2.2 Development of Utility Boiler The modern 660MW coal-fired boiler has some 6000 tons of pressure parts which include 500 km of tubing, 3.5 km of integral piping and 30,000 tube butt welds.It is the culmination
教材25页 of some fifty years development and while the basic concept of pulverized fuel firing into a furnace lined with evaporator tubes, with the combustion gases then passing over convection superheater and heat recovery surface, has remained unchanged, the advancement of steam conditions, increases in unit size and the properties of the fuel fired have required major changes in materials employed, fabrication techniques and operating procedures.2.2 电站锅炉的发展
现代660MW燃煤锅炉有大约6000吨的压力部件，其中包括500千米的受热面管材，3.5千米连接管，和30000个管接头焊口。这是经过大约50年发展的成果，并形成了至今未变的基本概念，即煤粉在布置有蒸发管束的炉膛内燃烧，然后烟气通过对流过热器和热回收表面。蒸汽参数的提高，机组容量的增大及燃料燃烧特性改进都要求在材料、制造技术和运行程序上相应发展。
In the years immediately following the second World War, is was customary to install in a power station, a greater number of boilers than turbines, the boilers feeding a range to which the turbines were connected.This arrangement reflected the inferior availability of boilers compared with turbines but increase in boiler availability in the late 1940s led to the acceptance of unitized boilers and turbines.The change to unitized boiler and turbine allowed reheat to become practical and, with the availability of high temperature steels, there followed a continuous advance in steaming conditions to the current standard cycle of 2400 lbf/in2(165.5bar), 568℃ with reheat to 568℃.To take full advantage of the more advanced steam conditions and to obtain the economies of size, the next fifteen years also saw a twenty-fold increase in unit size.二战后的一些年里，在电厂安装锅炉的数量多于汽轮机是很常见的，锅炉提供蒸汽到母管然后到汽机。这种布置反应了锅炉的可用性低于汽轮机。四十年代后期，随着锅炉可用性的提高，锅炉和汽机开始可以相互配套使用。这一变化使再热变得可行，而且随着高温钢材
29-6 可用性的提高，蒸汽参数不断变化，达到了当前的2400lbf/in2（165.5bar），568℃和568℃再热的标准循环。为充分利用更高的蒸汽参数和获得更大的经济性，在接下来的15年，机组容量又增加了20倍。
A utility normally procures plant from specialist manufactures who have responsibility for design, manufacture, erection and commissioning.While the manufactures carry out development of manufacturing process and continuously update their design methods, and change in operation conditions and size necessarily results in a new plant being of a prototype nature.While some new features can be tested in advance of construction the only real test of a new boiler design is in operation and with its associated turbine and generator.The commercial success of a new design is proved over the whole projected life of power station and utility, therefore, has to balance the immediate economic advantages of a new design in terms of improved efficiency, reduced capital costs, etc.against the risk of poor availability, need for major modifications, etc., which might result from a new development.A utility normally purchases plant against generating needs and the repercussions of poor initial availability are not only being unable to meet load demand but also having to use costly plant to make up the shortfall.This period of major advance in steam cycle and unit size therefore required quite exceptional interaction with manufacturers in design and fabrication area and development of operation and maintenance techniques to ensure that the economic gains did not prove illusory.电站设备一般向负责设计、制造、建设和调试的专业厂商购得。同时生产厂商实施生产过程的发展，不断修正设计方法，改变必要的运行参数和容量, 从而形成新电厂的原型。虽然一些新的特性可以在安装前进行测试，但一个新设计锅炉的真正测试是和汽轮发电机组配套运行后进行的。一个新的设计获得商业成功需要通过电站在整个设计寿命中的使用来证明。因此，需要平衡考虑由效率提高、投资成本减少等带来的直接经济效益，与新设计机组可能产生的可靠性低和需要大的改进等风险。公用事业公司一般依靠发电需求购买设备，并且最初可用性较低的影响不仅不能满足负荷需求，还需要使用昂贵设备以弥补不足。因此，在对蒸汽循环及机组容量进行较大改进的时期，必须和厂商在设计、制造领域，以及运行、维护技术领域密切合作，以保证经济利益的可靠。
2.3 Fuel and combustion
The fuels used in most boilers are coal, natural gas and oil.However, during the past few decades, nuclear energy has also begun to play a major role in at least the electric power generation area.Also, an increasing variety of biomass materials and process byproducts have become heat sources for steam generation.These include peat, wood and wood wasters, straw, coffee ground, corn husks, coal mine wastes(culm)[煤屑], waste heat from steelmaking
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29-7 furnaces and even solar energy.2.3 燃料及燃烧
大部分锅炉以煤、天然气和石油作为燃料。然而，在过去的几十年里，至少在发电领域核能开始扮演一个主要角色。同样，不断增加的各种生物质和工业副产品也成为生产蒸汽的热源。这些包括泥煤、木材及木材废弃物、麦秆、咖啡渣、玉米秆、煤矿废弃物（煤屑）、炼钢炉废热甚至太阳能。
The dominant fuel in modern U.S.central stations is coal, either bituminous, sub-bituminous or lignite.While natural gas or fuel oil may be the fuel of choice for selected future fossil fuel power plants, coal expected to continue its dominant role in supplying energy to new, base power utility power station boilers.现代美国中心电站以煤作为主要燃料，使用烟煤、次烟煤或褐煤。虽然天然气和燃油也许是未来化石燃料电厂的燃料选择，但对于带基本负荷的新电站，煤仍将是主要的锅炉燃料。
2.3.1 Coal classification
A coal classification system is needed because coal is a heterogeneous substance with a wide range of composition and properties.The properties of a typical China coal are showed in table 2-1.Coals are typically calssified by rank.This indicates the progressive alteration in the coalification process from lignite to subitiminous, bituminous and anthracite coals.The rank indicates a coal’s geological history and characteristics.表2-1（27页）
2.3.1 煤的分类
由于煤是一种不均匀的物质，且其组成和特性变动很大，所以建立煤的分类系统是很必要的。中国煤的性质如表2-1所示。以煤阶进行煤的分类是典型的做法。这表现为煤化程度的大小：从褐煤到贫煤、烟煤以及无烟煤。煤阶表明了煤的地质历史和主要特性。
The system used in the U.S.for classifying coal by rank was established by the American Society for Testing and Materials(ASTM).ASTM classification is a system which uses the volatile matter and fixed carbon(FC)results from the proximate analysis and the heating value of the coal as ranking criteria.This system aids in identifying commercial uses of coals and provides basic information regarding combustion characteristics.现在美国应用的煤分类标准是由美国材料试验学会（ASTM）建立的。其分类是通过煤的工业分析所确定的挥发分和固定碳的含量以及煤的发热量作为分类标准。这套系统目的在于确定煤的商业使用价值，并提供关于煤燃烧特性的基本信息。
2.3.2 Combustion systems
29-8 The combustion of fossil fuels within a boiler for steam raising purposes has been practised for many years.However, within the past two decades combustion techniques have been considerably refined in order to reduce atmospheric emissions and pollution to practicable minimum.2.3.2 燃烧系统
锅炉内化石燃料燃烧以产生蒸汽的技术已成熟多年。然而，在过去的二十多年中，为了将大气排放和污染降到可行的最低程度，燃烧技术得到了很大程度的提高。
Oil combustion systems Oil is burned in all utility boiler, in coal boiler to ignite the coal burners, to warm up the boiler and raise pressure before coal is admitted, and in oil fired boilers as the main load
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fuel.In general, the oil is residual Fuel Oil of 3500 sec.to 6500 sec.viscosity.In order to burn effectively this oil must be heated to 120-130℃ and divided or atomized into very small droplets.油燃烧系统
所有的电站锅炉都燃用油，在燃煤锅炉中点燃煤粉，在煤进入炉膛之前加热炉膛并升压，而在燃油锅炉中则作为主要负荷燃料。一般地，燃油都是粘度在3500 sec到6500sec的残渣燃料油。为了有效的燃烧，这些油必须被加热到120~130℃并被良好地分散或雾化成很小的微滴。
The use of this oil, cheaper than normal distillate(diesel/gas oil etc.)causes problems, amongst them, acid smuts and dust emissions.The smut problem is caused by the sulfur content of the oil, which may be up to 3%.In the early 1960s the utility undertook an intensive development program on oil burner design, which was aimed at removing the problems of oil fired emissions.This resulted in an oil burner, “the Standard Burner” which reduced emissions of carbon at very low excess air levels.Considerable work was also done in order to ensure that burner in a boiler received the same amount of air, and the current operating level for excess air in an oil fired unit is 2%.燃用渣油，要比一般的馏分油（柴油，汽油等）便宜，但又带来一些问题：酸性污染物和粉尘的排放。酸性污染问题是由石油中的硫产生的，硫分的含量有时可高达3%。在20世纪60年代早期，人们对油燃烧器设计进行了深入研究和开发，目的在于解决燃油的排放问题。由此诞生了一种油燃烧器——“标准燃烧器”，它可以在非常低的过量空气系数下减少碳排放。为保证锅炉中每个燃烧器获得同样多的空气也做了大量的工作。目前油燃烧过量空气系数运行水平为2%。
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Coal combustion systems Coal burners have been developed in a similar fashion to the oil burners, and considerable emphasis is placed upon feeding each burner with carefully regulated amounts of coal and oil.All coal fired boilers in the utility fire pulverized coal(produced by milling)which is very finely divided coal carried to the burner on a stream of air(primary air).The design effort directed at flow equalization has produced boilers which can be operated at lower excess air levels than previously, and thus have increased overall efficiency without increasing unburned carbon levels in the ash.煤燃烧系统 煤燃烧器的发展模式同油燃烧器类似，而且重点放在准确控制每只燃烧器煤和油的供给量。实际中所有的燃煤锅炉都是燃烧煤粉（由磨煤机生产），这些煤粉经过很好的粉碎，然后由空气流（一次风）送入燃烧器。同以前相比，在流动平衡上的设计成果现在已能使锅炉在较低的过量空气水平下运行，并在不增加飞灰含碳量水平的情况下提高了总的效率。
This, when combined with the development of low NOx burners will result in reduced gaseous emission in line with EEC directives and is the main objective of two boiler conversions(both complete)to establish the level to which NOx maybe reduced in the exhaust from 500MW coal fired boilers.A NOx reduction development trial is proposed on a third boiler design, 这样，结合低NOx燃烧器的开发，就使气体排放达到欧共体的标准，这也是两代锅炉转换（已完成）的主要目的，即设定500MW燃煤锅炉可能达到的NOx排放水平。在第三代锅炉的设计中进行了进一步降低NOx的开拓性试验。
The arrangement of coal-fired system components must be determined according to economic factors as well as the attributes of the coal.The performance in terms of product fineness, mill outlet temperature, and air-coal ratio must all be determined as part of overall combustion system design.煤燃烧系统部件的布置必须根据经济因素和煤的性质来确定。作为整个燃烧系统设计的性能参数，煤粉细度、磨煤机出口温度、空煤比等都必须达到要求。
Low NOx combustion systems The factors affecting NOx are the proportion of nitrogen chemically combined with the fuel, peak flame temperature, the available oxygen in the flame and the residence time of the gases within the system.Some of the coal bound nitrogen is released as volatiles as the chemical structure of the coal breaks down on entering the furnace.Nitric oxide produced from atmospheric nitrogen as “thermal NOx” can be
29-10 limited by minimizing residence times at high temperature, which limiting the amount of oxygen available to the fuel during the combustion stage results in the production of harmless nitrogen rather than NOx.低NOX燃烧系统
影响NOx生成的因素包括燃料含氮量、火焰峰值温度、火焰中的可用氧量以及气流在锅炉系统中的停留时间。当煤进入炉膛其化学结构被破坏时，一些煤中的化合氮就作为挥发分被释放出来。由大气中的氮生成的一氧化氮即“热力型NOx”可以通过减少烟气在高温区域的停留时间而得到控制，这样就会控制燃烧阶段中可用氧量，最后生成的是无害氮而不是NOx。
Since coal firing requires some excess oxygen in the combustion zone to achieve total carbon burnout and nitrogen free coal is unavailable, NOx reduction has to be performed by boiler and burner design.因为煤在燃烧区的燃烧需要一定的过量氧气以便使所有的碳燃尽，且不含氮的煤是难以获得的，因此NOx的减少必须依靠锅炉和燃烧器的设计来完成。
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Gas combustion systems Natural gas has been fired at power stations for main load purposes.However, gas has not been available to the utility for some years now and it is not envisaged that, as a premium fuel, it will ever be available again in any quantity.Propane is widely used in igniters for the oil burners in both main oil and coal fired boilers.天然气燃烧系统
天然气曾经作为电厂主要燃料。然而一些年来，没有太多的天然气可供电厂使用，并且人们没有正视这样的事实，即天然气作为一种优质燃料将会重新得到大量应用。
丙烷常常作为一种点火剂，广泛地应用于燃油锅炉和燃煤锅炉中的油燃烧器。
2.3.3 Fluidized-bed combustion A variation on PC combustion is fluidized bed combustion in which coal is burned with air in a fluid bed, typically a circulating fluidized bed(CFB).CFBs are best suited to low-cost waste fuels and low-quality or low heating value coals.Crushed coal and lime stone are fed into the bed, where the lime stone undergoes calcination to produce lime(CaO).The fluidized bed consist only of lime, with a few percent coal and recirculated coal char.The bed operates at significantly lower temperatures, about 427℃(800ºF), which thermodynamically favors low NOx formation and SO2 capture by reaction with CaO to form CaSO4.The steam cycle can be subcritical and potentially supercritical, as with PC combustion, and generating efficiencies are similar.The primary advantage of CFB technology is its capacity to
29-11 capture SO2 in the bed, and its flexibility to a wide range of coal properties, including coals with low heating value, high ash coals and low volatile coals, and changes in coal type during operation.Several lignite-burning CFB units have been constructed recently, and CFBs are well suited to co-firing biomass.2.3.3 流化床燃烧
流化床燃烧是煤粉燃烧方式的一种，采用这种燃烧方式时煤在空气中的燃烧发生在流化床中，典型的是循环流化床。循环流化床最适合于燃烧低成本废弃燃料、低品质或低热量煤。将煤粒和石灰石投入到床中，石灰石在床内煅烧成石灰。流化床中主要是石灰和少量的煤，煤焦在其中循环。运行中的床温很低，只有427℃(800℉)，在这个温度下的热力学环境有利于减少NOx的形成和捕集SO2，使之与CaO 反应生成CaSO4。对于煤燃烧，蒸汽循环可以是亚临界，也可能是超临界，它们具有相近的发电效率。循环流化床技术的最大的优点是它在床中捕捉SO2的能力和它对煤质的广泛适应性，其中包括低热量煤、高灰分煤和低挥发分煤，并且在运行中可以改变煤种。循环流化床锅炉适合与生物质共燃，最近就新建了几台燃烧褐煤的循环流化床机组。
The most commonly used circulating fluidized bed combustor is shown in Fig.2-1.Coal and coal char are burned while the coal, coal char, coal ash and sorbent are carried up through the furnace by combustion air.The solid materials are separated from the flue gas in
图2-1 循环流化床锅炉设计布置实例 教材29页
the cyclone and pass through a convective section where heat is transferred to boiler tubes generating high-pressure steam.Additional steam is generated by removing heat from the hot solids in the fluidized bed heat exchange section before they are returned to the furnace.There are no boiler tubes in the lower furnace because the rapid moving solids cause excessive erosion.NOx is managed through low temperature and staged injection of the combustion air.SOx emission is controlled via the lime sorbent in the bed.This saves significant capital for flue gas cleanup, but low SOx emission require low-sulfur coal, and NOx emissions are limited by combustion chemistry.Extremely low emissions levels would require the addition of flue gas clean-up units with the attendant cost increase.The largest CFB unit is 330MWe in China, and 600MW units have been designed, but no unit of this size has been built.如图2-1所示，目前最常用的流化床技术是循环流化床燃烧技术。煤和煤焦燃烧的同时，空气携带煤、煤焦、煤灰和脱硫剂通过炉膛。固体材料通过旋风分离器从烟气中分离出来，然后通过对流烟道部分，烟气把热量传给炉管以产生高压蒸汽。另一部分蒸汽是由流化床中的高温固体在返回炉膛前放出热量产生的。炉膛内固体快速运动会引起过量的磨损，因此炉膛底部不安装炉管。通过低燃烧
29-12 温度和空气分级燃烧来控制NOx的生成。SOx排放通过床中石灰脱硫剂控制。这些为烟气净化节省了大笔的投资，但是低的SOx排放需要燃烧低硫分煤，并且NOx的排放受燃烧反应的限制。极低的排放需要额外的烟气净化设备，同时会增加相应的维护成本。在中国最大的流化床锅炉是330MWe，设计最大的锅炉是600 MWe，但是还没有投建。2.4 Pulverizing System The development and growth of coal pulverization closely parallels the development of pulverized coal-firing technology.In order to achieve efficient combustion in the boiler furnace the coal leaving the burner must be sized so that it can burn rapidly and this means that it must be in the form of small particles that can quickly be heated up to ignition temperature and get ready access to the combustion air.The job of the pulverizers is to grind the feed coal down to a suitable size for the above purposes.Early systems used ball-and-tube pulverizers to grind coal and holding bins to temporarily store the coal before firing.Evolution of the technology to eliminate the bins and direct fire the coal pneumatically transported from the pulverizers required more responsive and reliable grinding equipment.Vertical air-swept pulverizers met this need.2.4 制粉系统
煤粉制备与煤粉燃烧技术的发展是同步的。为了使煤在炉膛中有效燃烧，煤在离开燃烧器时必须被粉碎到一定的大小，这样才能迅速燃烧，这就意味着煤必须被加工成小颗粒，才能被迅速加热到着火温度并和空气良好混合。磨煤机的工作就是把煤磨碎到符合上述要求的合适的大小。较早的系统使用筒式球磨机磨煤粉，并且在燃烧前利用储仓暂时储存煤粉。如果对该技术进行改进，去掉中间储仓而将从磨煤机出来的煤粉直接送去燃烧，就会对磨煤机的可靠性有很高的要求。
On pressurized pulverizing systems the primary air fan which provides the pulverized fuel transport medium is situated before the pulverizer and there handle clean air and is not subject to erosive wear as is an exhaust fan.This is the chief advantage of the pulverizing system, however the pulverizer does need sealing air which is usually provided by a separate fan at a pressure higher than that of the pulverizer interior.正压制粉系统中，提供煤粉输送介质的一次风机位于磨煤机前，因而它运送的是清洁空气，不会像排粉风机一样受到侵蚀磨损。这是正压磨煤系统的主要优点。然而，磨煤机需要由单独风机提供高于磨煤机内部压力的密封空气。
A disadvantage of the pressure type pulverizer is that it must be absolutely air tight in order to avoid pulverised fuel leakage to the atmosphere.Conversely the standard of sealing on a suction pulverizer need not be so high, but it must not be
29-13 allowed to deteriorate too far as the inwards leakage, being cold air, will make it difficult to dry the wetter coals.This leakage air is also unmeasured as regards its quantity, and if excessive under certain conditions produces a high air/coal ratio which may be explosive should there be an ignition source.正压磨煤机的一个缺点是它必须完全由空气密封以避免煤粉泄露到大气中。相对来说，负压磨煤机的密封标准并不需要这样高，但也不允许漏入过多空气，因为冷空气难以干燥湿煤。这种方式泄露的空气量也无法测量，如果达到高的空/煤比，遇到明火则可能发生爆炸。
2.4.1 Vertical air-swept pulverizers
The roller passes over a layer of granular material, compressing it against a moving table.The movement of the roller causes motion between particles, while the roller pressure
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creates compressive loads between particles.Motion under applied pressure within the particle layer cause attrition(particle breakup by friction)which is the dominant size reduction mechanism.The compressed granular layer has a cushioning influence which reduces grinding effectiveness but also reduces the rate of roller wear dramatically.When working surfaces in a grinding zone are close together, near the dimensions of single product particles, wear is increased by three body contact(roller, particle and table).Wear rates can be three body contact has also been observed in operating mills when significant amounts of quarts bearing rock are present in sizes equal to or greater than the grinding layer thickness.2.4.1 中速磨
磨辊在一层耐磨层上滚动，通过移动的磨盘把煤压碎。磨辊的运动引起煤粒间的相互运动同时磨辊的压力在煤粒间形成压力负荷。一定压力下在煤粒层上的运动引起摩擦（煤粒依靠摩擦力破碎），这就是磨煤机的工作原理。耐磨层具有缓冲作用，虽然降低了磨的效率，但也大大降低了磨辊的磨损。当磨煤区的工作面间距离很近时，比如到了一个颗粒大小，三个部件（磨辊，颗粒，磨盘）间的磨损就会大大增加，磨损速率会是正常磨煤机的100倍。当带有石英的石头尺寸等于或大于磨层厚度时，也会在运行中发生三部件接触的磨损。
As grinding proceeds, fine particles are removed from the process to prevent excessive grinding, power consumption and wear.Fig.2-2 presents a simplified MPS vertical pulverizer, showing the essential elements of a vertical air-swept design.A table is turned from below and rollers, called tires, rotate against the table.Raw coal is fed into the mill from above and passes between the rollers and the rotating table.Each passage of the particles under the rollers reduces the size of coal.The combined effects of centrifugal force and displacement of the coal layer by the rollers spills partly ground coal off the outside edge of the table.An upward flow of air fluidizes
29-14 and entrains this coal.随着磨煤的进行，为了防止过度磨制和降低能耗及磨损，磨好的煤粉从磨煤机中排出。图2-2是MPS型中速磨的示意图，显示了中速磨煤机的基本组成。在磨煤机下部有一个转动的台面，称为辊胎的辊子在台面上滚动。原煤由上部的磨煤机给入，然后在磨辊和转动的磨盘间经过，磨辊下的煤就被磨碎了。离心力加上磨辊对煤层的沉降力共同作用，将部分磨好的煤粉挤出磨盘边缘，由上升的空气流流化并携带这些煤粉。
图2-2 磨煤机内部的颗粒循环
The point where air is introduced is often called the air port ring, nozzle ring or throat.Rising air flow, mixed with the coal particles, creastes a fluidized particle bed just above the throat.The air velocity is low enough so that it entrains only the smaller particles and percolates with them through the bed.The air-solids flow leaving the bed forms the initial stage of size separation or classification.The preheated air stream also dries the coal to enhance the combustion process.空气进入点一般称为进风环，喷嘴环或者喉部。上升的空气流与煤粒混合在进风环上面产生流化的颗粒床。空气的流速很低，以至于只能携带少部分的煤粒通过床层过滤。空气和煤粒离开流化床形成了第一步的分离。预热的空气同时干燥煤粉以保证煤粉的有效燃烧。
Vertical pulverizers are effective drying devices.Coal with moisture content up to 40% have been successfully handled in vertical mills.Higher moisture levels are possible, but the primary air temperature needed would required special structure materials and would increase the chance of pulverizer fires.A practical moisture limit is 40%, by weight, requiring air temperature to 750ºF(398℃).立式中速磨是有效的干燥装置。即使煤中水分到40%也能在中速磨中很好地得到干燥，干燥水分再高些的煤粉也是可能的，但是需要的一次风温度则要求使用特殊材料，并且增加了磨煤机着火的可能。实际运行的水分最大值是40%（质量），此时要求一次风温高达750℉。
As the air-solids mixture flows upward, the flow area increase and velocity decreases returning larger particles directly to the grinding zone.The final stage of size separation is
教材31页 provided by the classifier located at the top of the pulverizer.This device is a centrifugal separator.The coal-air mixture flows through openings angled to impart spin and induce centrifugal force.The coarser particles impact the perimeter, come out of suspension and fall back into the grinding zone.The finer particles remain suspended in the air mixture and exit to the fuel conduits.空气煤粉向上流动时，由于流动面积增大使流动速度降低，大粒径的煤粒就会回落到磨盘上。最后的煤粉分离采用磨煤机上部的粗粉分离器，粗粉分离器是利用离心力的分离装置。风粉混合物以一定角度进入，从而发生旋转并产生离心力。粗一点的煤粉冲击到分离器的周29-15 边，不再保持悬浮状态而回落到磨盘上。风粉混合物中的细煤粉颗粒保持悬浮状态，并最终上升进入煤粉管。
2.4.2 Low speed pulverizers The oldest pulverizer design still in frequent use is the ball and tube mill.This is a horizontal cylinder, partly filled with small diameter balls(Fig.2-3).The cylinder is lined with wear resistant material contoured to enhance the action of the tumbling balls and the balls fill 25% to 30% of the cylinder volume.The rational speed is 80% of that at which centrifugal force would overcome gravity and cause the balls to cling to the shell wall.Grinding is caused by the tumbling action which traps coal particles between balls as they impact.图2-3 典型的钢球磨制粉系统
2.4.2低速磨
筒式钢球磨是现在仍在使用的最早的磨煤机。它是一个卧式的筒体，里面装有小直径的钢球。筒体内衬耐磨材料以加强球的滚动，球占筒体总容积的25%到30%。转速取离心力可以克服重力时速度的80%，这样可以使钢球贴在筒体的内壁上。通过筒体转动时钢球的碰撞来实现煤粉的磨制。
Ball-and-tube mills may be either single or double ended.In the former, air and coal enter through one end and exit the opposite.Double ended mills are fed coal and air at each end and ground-dried coal is extracted from each end.In both types, classifiers are external to the mill and oversize material is injected back to the mill with the raw feed.Ball-and-tube mills do not develop the fluidized bed which is characteristic of vertical mills and the poor mixing of air and coal limits the drying capability.When coal with moisture over 20% must be ground in ball-and-tube mills, auxiliary equipment, usually crusher dryers, must be used.筒式钢球磨有单进单出和双进双出两种。对于单进单出型，空气和煤从一端进入从另一端流出。双进双出型磨煤机是空气和原煤从两端进入，磨好的干燥的煤粉从两端流出。对于这两种类型，粗粉分离器布置于磨煤机的外部，粒径过大的粗粉被送回到磨煤机与原煤混合。筒式钢球磨不具有类似立式磨的流化床特点，同时由于空气和煤粉的混合不均匀限制了干燥能力。如果筒式钢球磨要磨的煤中水分高于20%，就必须使用辅助的干燥装置，比如破碎干燥机。
Ball-and-tube mills have largely been supplanted by vertical air-swept pulverizers for new boilers.They typically require larger building volume and higher specific power consumption than the vertical air-swept pulverizres.They are also more difficult to control and have higher metal wear rates.They are, however, well suited for grinding extremely abrasive, low moisture and difficult material such as petroleum coke.Their long time makes them effective for fine grinding.29-16
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对新建锅炉来说，中速磨已经大量的取代了筒式钢球磨。相对于中速磨，筒式钢球磨往往需要大的建筑空间和较高的能耗。同时，筒式钢球磨难于控制且有较高的磨损速度。但是，筒式钢球磨能很好的适应极具磨损作用的、低水分的难磨燃料，比如石油焦。煤在其中较长的停留时间可以实现有效的磨制。
2.4.3 Pulverizing systems
Pulverizers are part of lager systems, normally classified as either direct-fired or storage.In direct firing, coal leaving each mill goes directly to the combustion process.The air, evaporated moisture and the thermal energy which entered the mill, along with the ground coal, all become part of the combustion process.Storage systems separate the ground coal from the air, evaporated moisture and the thermal energy prior to the combustion process.Stored ground coal is then injected with new transport air to the combustion process.Bin storage systems are seldom used in steam generation today, but are still used with special technologies such as coal gasification and blast furnace coal injection.Of the 1000 or so MPS pulverizers in service in the U.S.more than 90% are used in direct-fired systems.2.4.3制粉系统
磨煤机只是庞大的制粉系统的一部分，制粉系统一般有直吹式和中储式两种。在直吹式系统中，从磨煤机出来的煤粉直接参与燃烧过程，同时参与的还有空气、水蒸汽和通入磨煤机的热能。中储式系统把煤粉从空气、水蒸汽和通入磨煤机的能量中分离开再去燃烧。储仓中的煤粉由新的一次风输送到燃烧设备。目前生产蒸汽的过程中很少采用中储式制粉系统，但是很多特殊的场合仍然需要，比如煤气化和高炉投煤。目前在美国运行的中速磨大约有1000台，其中99%以上的是直吹式系统。
The essential elements of a direct-fired system are:
(1)A raw coal feeder that regulates the coal flow from a silo or bunker to the pulverizer.(2)A heat source that preheat the primary air for coal drying.(3)A pulverizer(primary air)fan that is typically located ahead of the mill(pressurized mill)as a blower, or after the mill(suction mill)as an exhauster.(4)A pulverizer, configured as either a pressurized or suction unit.(5)Piping that directs the coal and primary air from the pulverizer to the burners.(6)Burners which mix the coal and balance of combustion air, and(7)Control and regulating devices.直吹式系统的主要部件有：
(1)给煤机，通过煤仓调节进入磨煤机的给煤量。(2)热源，用来预热干燥煤粉的一次风
29-17(3)一次风机，典型的情况是作为鼓风机布置于磨煤机之前（正压系统），或作为排粉风机位于磨煤机之后（负压系统）
(4)磨煤机，作为正压系统或负压系统的主体部分。(5)管路，把煤和一次风从磨煤机输送到燃烧器(6)燃烧器，混合煤粉和平衡燃烧空气(7)控制和调节装置
These components can be arranged in several ways on project economics.With pressurized pulverizers, the choice must be made between hot primary air fans with a dedicated fan for each mill, or cold fans located ahead of a dedicated air heater and a hot air supply systems have a lower capital cost because a dedicated primary air heater is not required.Cold fan systems have lower operating costs which, on larger systems, may offset the higher initial cost.根据工程的经济性，以上部件可以按照不同的形式布置。在正压系统中，需要做出选择，是采用热一次风风机（每个磨一个风机），还是采用冷风风机（布置在特定的空气加热器前面）。热风输送系统初始投资费用较低，因为不需要特定的空气加热器。对大型机组而言，冷风风机系统具有较低的运行费用，可以补偿较高的初始投资。
The terminology for air-swept pulverizers refers to the air introduced for drying and transport as primary air.Control of primary air is of vital importance to proper pulverizer system operation.For direct-fired or storage systems and hot fan and cold fan systems, common control elements are found.Primary air must be controlled for flow rate and pulverizer outlet temperature.This control is achieved by three interrelated dampers.中速磨这个术语是指空气引入到磨煤机中作为一次风用来干燥和输送煤粉。一次风的控制对制粉系统的正常运行是非常重要的。不管是直吹式还是中储式制粉系统，也不管采用热风还是冷风风机系统都需要普遍的控制。必须控制一次风量和磨煤机出口温度，这个控制由三个相互联系的节气阀来实现。
Two of these, hot and cold air dampers, regulate air temperature to the mill and these dampers are usually linked so that as one opens, the other closes.The third damper is independent and controls air volume.Some manufacturers use only two dampers, but lack of stability or slow load change response can offset the cost advantages.其中的两个是热和冷的节气阀，用来调节磨煤机的空气温度，这些节气阀通常是相互关联的，从而保证一个开启另一个则关闭。第三个节气阀是独立的，用来控制空气容积。一些生产商只采用两个节气阀，但是缺乏稳定性，而变负荷时的低反应能力抵消了初投资的减少带来的好处。
29-18
2.5 System Arrangement and Key Components.Modern boilers are a complex configuration of thermal-hydarulic(steam and water)sections which preheat and evaporate water, and superheat steam.These surfaces are arranged
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so that:1)the fuel can be burned completely and efficiently while minimizing emissions, 2)the steam is generated at the required flow rate, pressure and temperature, and 3)the maximum amount of energy is recovered.A relatively simple coal-fired utility boiler is illustrated in Fig.2-4.the major components in the steam generating and heat recovery system include:(1)Furnace and convection pass(2)Steam superheaters(primary and secondary)(3)Steam reheaters(4)Boiler or steam generating bank(industrial units only)(5)Economizer(6)Steam drum(7)Attemperator and steam temperature control system(8)Air heater
图2-4 燃煤锅炉（机组）
2.5 系统布置和主要部件
现代锅炉具有复杂的热力—水力（蒸汽和水）受热面结构，以预热和蒸发水，产生过热蒸汽。这些受热面是这样布置的：（1）燃料在最小污染排放的情况下完全有效地燃烧；（2）按要求产生一定流量、压力和温度的蒸汽；（3）最大限度地回收能量。一个相对简单的燃煤电站锅炉如图2－4所示。产生蒸汽和热量回收系统中的主要部件有：（1）炉膛和对流烟道（2）蒸汽过热器（第一级和第二级）（3）蒸汽再热器（4）产生蒸汽的管组（仅仅存在于工业锅炉中）（5）省煤器（6）汽包（或锅筒）（7）减温器和蒸汽温度控制系统（8）空气预热器
2.5.1 Furnace The furnace is a large enclosed open space for fuel combustion and for cooling of the flue gas before it enters the convection pass.Excessive gas temperatures leaving the furnace and entering the tube bundles could cause particle accumulation on the tubes or excessive tube metal temperature.The specific geometry and dimensions of the furnace are highly influenced the fuel and type of combustion equipment.In this case, finely ground or pulverized coal is blown into the furnace where it burns in suspension.The products of combustion then rise through the upper
29-19 furnace.The superheater, reheater and economizer surfaces are typically located in the horizontal and down-flow sections of the boiler enclosure(convection
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pass).2.5.1炉膛
炉膛是一个四周封闭的开口大空间，燃料在其中燃烧，产生的烟气在进入对流烟道前得到冷却。离开炉膛进入管束的烟气温度过高则会导致烟尘微粒沉积在管壁上或使金属管壁超温。燃料和燃烧设备的类型对炉膛的几何形状和尺寸影响很大。在这种情况下，磨细的煤粉被送入炉膛悬浮燃烧。燃烧产物上升穿过炉膛上部。过热器、再热器和省煤器等受热面被特定布置于锅炉围墙内部的水平或垂直烟道内（对流烟道）。
In modern steam generators, the furnace and convection pass walls are composed of steam-or-water cooler carbon steel or low alloy tubes to maintain wall metal temperatures within acceptable limits.These tubes are connected at the top and bottom by headers, or manifolds.These headers distribute or collect the water, steam or steam-water mixture.The furnace wall tubes in most modern units also serve as key steam generating components or surfaces.The tubes are welded together with steel bars to provide membrane wall panels which are gas-tight, continuous and rigid.The tubes are usually prefabricated into shippable membrane panels with openings for burners, observation doors, sootblowers(boiler cleaning equipment)and gas injection ports.在现代蒸汽发生器中，炉膛和对流烟道的炉墙是由碳钢或低合金钢的汽冷或水冷壁组成，以维持炉墙的金属温度在允许的范围内。这些管子在顶部和底部由联箱或母管连接在一起。这些联箱用来分配或收集水、蒸汽或汽水混合物。在最现代化的机组中，炉墙管道也作为主要的产生蒸汽的部件或受热面。这些管子用钢条焊接在一起，组成气密的、连续的、刚性的膜式墙。这些管道通常预制成可装运的膜板，并且板上留有燃烧器口、观察孔、吹灰器口（锅炉清洁设备）和燃气喷入口。
2.5.2 Superheaters and reheaters Superheaters and reheaters are specially designed inline tube bundles that increase the temperature of saturated steam.In general terms, they are simple-phase heat exchangers with steam flowing inside the tubes and the flue gas passing outside, generally in cross flow.These critical components are manufactured from steel alloy material because of their high operating temperature.They are typically configured to help control steam outlet temperatures, keep metal temperatures below acceptable and control steam flow pressure loss.2.5.2 过热器和再热器
过热器和再热器被专门设计成顺列管束，用来提高饱和蒸汽的温度。一般形式下，它们
29-20 是简单的单相换热器，蒸汽在管道内流动，烟气从外面经过，通常二者是交叉流动。由于其较高的运行温度，这些关键的部件一般用合金钢制造。典型的布置通常有利于控制出口蒸汽的温度，保持金属温度低于其可接受的极限和控制蒸汽流动的压力损失。
The main difference between superheaters and reheaters is the steam pressure.In a typical drum boiler, the superheater outlet pressure might be 2700 psi(186bar)while the reheater outlet might be only 580 psi(40bar).The physical design and location of the surfaces depends on the desired outlet temperatures, heat absorption, fuel ash characteristics and cleaning equipment.These surfaces can be either horizontal or vertical.The superheater and sometimes reheater are often divided into multiple sections to help control steam temperature and optimize heat recovery.过热器和再热器的主要区别是蒸汽压力。在典型的汽包锅炉中，过热器的出口压力为2700psi（186bar），而再热器的出口压力为580psi（40bar）。受热面的结构设计和布置取决于所要求的出口温度、吸热量、燃料的灰分特性和清洁设备。这些受热面可以呈水平或垂直布置。过热器和有的再热器经常被分为几段以利于控制蒸汽温度和优化热量回收。
Superheater types Two basic types of superheaters are available depending on the mode of heat transfer from the flue gas.The original type was the convection superheater, for gas temperatures where the portion of heat transfer by radiation from the flue gas is small.With a unit of this design, the steam temperature leaving the superheater increase with boiler output because of decreasing percentage of unit heat input that is absorbed in the furnace.This result in more heat available for superheater absorption.Because convection heat transfer rate are almost a direct function of gas flow rate and therefore boiler output, the total absorption in the superheater per pound of steam, and therefore steam temperature increase with boiler output(see Fig.2-5).This effect is increasingly pronounced the farther the superheater is located from the furnace and the lower the gas temperature entering the superheater.过热器的类型 根据烟气侧的传热方式，过热器可分为两种基本类型。最初的一种是对流过热器，从烟气吸收的辐射热量很小。在这样的机组中，蒸汽温度随锅炉负荷的增加而升高，这是因为炉膛吸收单位输入热量的百分比下降。这导致过热器吸收了更多的热量。因为对流传热速率几乎与烟气流率即锅炉负荷成直线关系，因此，过热器中每磅蒸汽的总吸热量以及蒸汽的温度都会随锅炉负荷而增长（见图2－5）。过热器布置得离炉膛越远，进入过热器的烟气温度越低，这种效果越明显。
A radiant superheater receives the energy primarily by thermal radiation from the furnace with little energy from convective heat transfer.It usually takes the form
29-21 of widely spaced [24 in.(609.6mm)] or large side spacing steam-cooled wingwalls or pendants superheat platens
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图2-5 布置有对流和辐射过热器的在一定负荷范围内出口汽温基本均匀 located in the furnace.It is some times incorporated into the furnace enclosure curtain walls.Because the heat absorption by furnace surfaces dose not increase as rapidly as boiler output, the radiant superheater outlet temperature declines with an increasing boiler output, as shown in Fig.2-5.辐射式过热器主要吸收来自炉膛的辐射热，对流传热量很少。一般采用较大间距（24英寸或很大的侧边距）的屏式凝渣管或悬吊屏式过热器的型式布置于炉膛中。有时这种过热器和包墙管组合成一体。因为炉膛受热面吸热不如锅炉负荷增长快，所以随着锅炉负荷的增长辐射式过热汽温度反而下降，如图2－5所示。
In certain cases the two opposite sloping curves have been coordinated by the series combination of radiant and convectional superheaters to give a flat superheat curve over a wide load range, as indicated in Fig.2-5.A separately fired superheater can also be used to produce a flat superheat curve.某些情况下，在较大的负荷范围内，这两条变化趋势相反的曲线可由一系列联合的辐射、对流过热器叠加为平缓的过热曲线，如图2-4所示。一个单独加热的过热器也能产生平缓的过热曲线。
The design of radiant and convective superheaters requires extra care to avoid steam and flue gas distribution difference which could lead to tube overheating.Superheaters generally have steam mass fluxes of 100,000 to 1,000,000 lb/h ft2[136 to 1356 kg/(m2·s)] or higher.These are set to provide adequate tube cooling while meeting allowable pressure drop limits.The mass flux selected depends upon the steam pressure and temperature as well as superheater thermal duty.In addition, the higher-pressure loss associated with higher velocities improves the steam side flow distribution.辐射和对流式过热器的设计需要特别注意避免因蒸汽和烟气流量分配不均而造成的管子超温。一般过热器中有100,000到1,000,000lb/hft(136到1356kg/ms)或更多的蒸汽质量流量。这种设置是在允许压降的范围内对管子内部进行充分的冷却。质量流量的选择取决于蒸汽的压力和温度，还有过热器的热负荷。此外，高速下的高压损会改善蒸汽侧流场分布。
222.5.3 Economizers and heaters.Economizers and air heaters perform a key function in providing high overall boiler thermal efficiency by recovering the low level, i.e., low temperature, energy from the flue gas before it is exhausted to the atmosphere.For each 40ºF(22℃)that
29-22 the flue gas is cooled by economizer or air heater, the overall boiler efficiency increases by approximately 1%.Economizers recover the energy by heating the boiler feedwater while air heaters heat the combustion air.Air heating also enhances the combustion of many fuels and ensuring stable ignition.2.5.3 省煤器和空气预热器
省煤器和空气预热器在提高锅炉总的热效率方面发挥着重要作用, 它们回收了排入大气前烟气中的低品位热量，也就是低温热量。烟气被省煤器或空气预热器冷却每40℉（22℃），总的锅炉效率就会被提高大约1%。省煤器吸热加热锅炉给水，空气预热器则是加热燃烧空气。热空气强化了多种燃料的燃烧，并保证了稳定的着火。
Economizers The economizer is a counterflow heat exchanger for recovering energy from the flue gas beyond the superheater and, if used, the reheater.It increases the temperature of the water entering the steam drum.The tube bundles are typically an arrangement of parallel horizontal serpentine tubes with the water flowing inside but in the opposite direction(counterflow)to the flue gas.Tube spacing is as tight as possible to promote heat transfer while still permitting adequate tube surface cleaning flue gas side pressure loss.By design, steam
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is usually not generated inside these tubes.省煤器 省煤器是一种逆流布置的热交换器，在流过过热器或再热器（如果使用）的烟气中获取能量。它提高了汽包进水的温度。其管束布置是一种典型的平行水平蛇形管束，水在管内流动而烟气在外侧反方向（逆流）流动。管子间尽量紧密以强化传热，同时要求有足够的管子表面清洁空间和合理的烟气侧压损。根据设计，这些管子内一般不会产生蒸汽。
The most common and reliable economizer design is the bare tube, in-line, crossflow type.When coal is fired, the flyash creates a high fouling and erosive environment.The bare tube, in-line arrangement minimizes the likelihood of erosion and trapping the ash as compared to a staggered arrangement.It is also the easiest geometry to be kept clean by sootblowers.However, these benefits must be evaluated against the possible larger weight, volume and cost of this arrangement.最普通、最可靠的省煤器设计就是光管、顺列、交叉流省煤器（如图2-6）。煤燃烧后，飞灰就会产生一种高污垢、侵蚀的环境。相对于如图2-6的错列布置，这些顺列布置的光管就会尽可能减少飞灰粘附、侵蚀的可能性。这也是通过吹灰器保持清洁的最简单的几何形状。然而，这种布置的好处必须要结合它大重量、大空间以及造价进行综合评估。
29-23 To reduce capital cost, most boiler manufacturers have built economizers with a variety of fin types top enhance the controlling gas side heat transfer rate.Fins are inexpensive nonpressure parts which can reduce the overall size and cost of an economizer.However, successful application is very sensitive to the flue gas environment.Surface clean ability is a key concern.为减少投资，大多数锅炉省煤器应用了各种鳍片以强化烟气侧的传热效率。鳍片是廉价的非承压物件，它可减少省煤器的总尺寸和造价。然而，成功的应用对于烟气环境是非常敏感的。表面的清洁能力是一关键因素。
Air heaters The air heater utilises the heat in the boiler flue gases leaving the economizer to heat the combustion air and provide hot air for drying coal.The air outlet temperature limit in coal fired plant is directed by the coal mill exit temperature and capacity of the tempering air system with the gas outlet temperature limited by considerations of fouling of the heat transfer surface and corrosion of downstream equipment.空气预热器 空气预热器是利用经过省煤器的锅炉烟气携带的热量加热燃烧空气，并提供干燥煤粉的热空气。在燃煤电厂中，空气预热器的出口温度受限于磨煤机的出口温度和调温风系统容量，烟气出口温度则要考虑传热表面的污染和后面设备的腐蚀情况。
On older boiler tubular or plate recuperators [间壁式换热器]were generally used which were large, difficult to clean and did not lend themselves to easy replacement of damaged heating surface.On all modern boilers regenerators [回转式] are used.在较老的锅炉中一般采用管式或板式空预器，体积大，很难清理，而且坏损的传热表面不易替换。现代锅炉都采用回转式。
The most significant feature of regenerative air heaters, is the marked saving in space compared with recuperative designs.This stems from the adoption of a closely packed heating surface matrix, which is permissible only if good soot-blowing facilities are available to keep it clean.回转式空气预热器的最大特点是显著地节省了空间。回转式空预器采用紧密的受热面布置方式，必须采用性能良好的吹灰器使其保持清洁。
The heat transfer surface consists of steel or Corten plates pressed to specific profile.The plates are 0.5 mm to 0.8 mm thick and are generally compressed and packed into solid steel containers which are then placed into the supporting structure.The profile of the plates is optimized to give high thermal performance with the minimum of pressure loss within the constraint of being adequately cleaned by
29-24 soot-blowing.受热面由压制成特殊形状的钢板或考登钢板组成。这些板子厚0.5到0.8mm，一般被压紧并装进置于支撑结构上的钢制仓体。这些板子的形状经过优化，具有很高的传热效率，同时要在使用吹灰器充分保持清洁的情况下保证压损最小。
For a 660MW unit there are two air heaters, each 14.6 m in diameter and weighing some 500 tons each.The surface area of the heat transfer surface is some 100,000m2 in total.For coal-fired plant the typical temperatures would be a gas inlet of 535℃ and outlet of 120℃ with an air inlet of 32℃ and outlet of 290℃.The performance of the air heater can be expressed in terms of the efficiency of heat transfer, pressure loss and air dimensional groups Reynolds, Prandtl and Stanton numbers.By carrying out laboratory scale rig test these relationships can be established for each type of air-heater element.This allows the possibility of optimizing designs, estimating the possible performance of newly developed element 教材37页
geometries and the effect of replacement element type which may be required because of fouling problems.一台660MW的单元机组配有两台空气预热器，每台直径14.6m，重约500吨。传热元件的表面积总共约100,000平方米。燃煤电厂典型的温度应是烟气进口335℃，出口120℃，空气进口32℃，出口290℃。空气预热器的性能主要表现在传热效率、压损以及空气对烟气侧的泄漏上。前两项能被理想的表示为一组无量纲数：雷诺数、普朗特数和斯坦顿数的关系。通过实验室规模试验可以确立每种空气预热器组件的关系式。这就可以进行优化设计，估算新开发部件的几何性能，以及评估由于灰污问题而需使用替代部件的效果。
2.6 On-load Cleaning Boilers The effective utilization of fossil fuels for power generation depends on a great extent on the capability of the steam generating equipment to accommodate the inert residuals of combustion, commonly known as ash.Soot-blowers are provided to remove combustion deposits from the boiler surface and ensure effective heat transfer to the steam.Steam is used almost exclusively as a blowing medium on the Continent but many air installations are in use in the USA.2.6 锅炉在线吹灰
是否高效的燃烧化石燃料来生产电力很大程度上取决于蒸汽产生设备对煤燃烧产物（煤灰）的适应性。吹灰器用来吹扫沉积在锅炉受热面上的积灰来保证有效地向蒸汽传热。在英国吹灰介质大部分用蒸汽而在美国一般用空气。
Furnace Wall Blower Using Steam or Air As required the short lance rotates forward into the furnace and the air or steam
29-25 is turned on as the blowers clear the wall tubes.The total travel is about 200~250mm.Dependent on the design the lance either turns between an arc of 120ºor can make to several complete turns until a limit switch reserves the drive and reacts the lance.The cleaning radius is 1.5 m ~2.0m.(1)应用蒸汽或空气的炉膛吹灰器
按照要求，短伸缩式吹灰器在吹扫炉膛壁面时向前旋转推进，同时打开空气或蒸汽。其总的行程大约200-250mm。根据设计要求，吹灰枪可以在120°范围内摆动或者在限位开关下做整圈的运动，直到吹灰枪缩回。这种吹灰器的吹扫半径为1.5-2m。
Furnace wall blowers can also use water but few are in service.They are used for cleaning tenacious or molten slag from furnace walls with a low velocity jet.A variable speed motor ensures that the water jet impinge with a uniform dwell time on the tube surfaces.炉膛的吹扫介质也可以用水，但实际中很少应用。水通常用来在低速下清除炉膛内顽固的熔融的渣。用变速马达来保证喷水在受热面上有相同的停留时间。
Long Travel Blowers Long travel blowers are used to clean the superheater, reheater and sometimes the economizer surfaces.When the blower is initiated the lance moves forward and rotates simultaneously so that the oppose jets describe a helical motion.When the jets clear the boiler wall the blowing medium is turned on and passed to the jets.(2)长伸缩式吹灰器
长伸缩式吹灰器用来吹扫过热器、再热器有时还有省煤器。当吹灰器启动时，吹灰枪向前移动，同时旋转来保证对冲的射流形成螺旋状的运动。当利用喷口吹扫炉墙时，就打开吹灰介质使其流向喷口。
When the lance is at full travel, it turns through 90º thus tracing a helical path in the reverse direction which bisects the path in the forward direction.Unsupported lance lengths up to 16.75m are practical thus giving the boiler designer boiler widths up to 33.5m.当吹灰枪行程达到最大时，吹灰枪旋转90度角，这样在返回时与进入的吹灰部分错开。没有支撑的吹灰枪长度可达16.75m，因此锅炉炉宽可以设计到33.5m。
Sonic soot blowers Sonic soot blowers are on trial in a variety of positions on utility boilers.The device is a low frequency(20Hz)sound generator driven by compressed air, and produces resonant frequency waves, which will clean enclosures up to 4900 m3.Results of trials have been mixed and it is too early to predict the extent to which
29-26 sonic blowing will be used.(3)声波吹灰器
声波吹灰器在电站锅炉不同位置进行了试验。这个装置是个压缩空气驱动的低频(20Hz)发声器，产生共振频率波，可以吹扫4900m3的空间。试验结果是个综合效果，因此预言声波吹灰器的应用范围还为时过早。
Until recently, steam was used exclusively for soot blowing.Air was first used in the USA.目前为止，一直采用蒸汽吹灰，空气吹灰的首次应用是在美国。
Air has the following advantages: Effective soot blowing is available at all loads. Maintenance of soot blowing is considerably reduced due to the absence of condensate, thermal shock and erosion on mechanism, lance and nozzles.教材38页
No warming through of air pipe work etc.is required and drainage of the pipe work is considerably reduced when compared to steam blowing. Insulation of the pipe work is not required. The incidence of boiler tube erosion leading to tube failure and boiler outage is reduced by 50% or more. Air heater plates give twice the effective life when air blown. Maintenance of the compressors and soot blowers is less extensive and less costly than maintenance of an equivalent steam system including the steam pressure reducing stations.空气吹灰有以下优点：
在任何负荷下都可以得到有效的吹灰。
由于没有凝结水、热冲击和对吹灰枪、喷嘴等部件的磨蚀，吹灰器的维护费用大大降低。
对空气管件不需要预热，并且相对于蒸汽吹灰，凝结水的排放大大减小。管件不需要保温。
由于炉管磨蚀造成的故障和停炉减少了50%或更多。空气吹灰可以使空气预热器的受热面寿命增加一倍。
相对于包括蒸汽减压站的蒸汽吹灰系统，空气压缩机和吹灰器及系统的维护费用大大降低。
To set against these considerable advantages is the additional capital cost of the compressors, motors, switchgear, cables and compressor house.However, operational data from 500MW boilers indicates that the energy consumption of equivalent steam
29-27 and air systems are comparable.抛开以上优点，空气吹灰也有其他的一些附加初始费用，如空压机、马达、开关设备、电缆和压缩机房。但是，从500MW锅炉的运行数据上来看，两种吹灰系统的能耗相当。
2.7 Energy balance In accordance with the first law of thermodynamics the energy balance around the steam generator envelope can be stated as: Energy entering the system – Energy leaving the system = Accumulation energy in the system.Since a steam generator should be tested under steady-stated conditions, such that accumulation is zero, the equation is: Energy entering the system = Energy leaving the system Energy entering the system is the energy associated with the entering mass flow streams and auxiliary equipment motive power.Energy leaving the system is the energy associated with the leaving mass flow streams and heat transfer to the environment from the steam generator surfaces.2.7 能量守恒
由热力学第一定律，蒸汽发生器系统的能量平衡如下所述： 进入系统的能量-离开系统的能量 = 系统内部能量的积累
因为蒸汽发生器应在稳态下检测，这样积累的能量就为0，其方程为： 进入系统的能量 = 离开系统的能量 进入系统的能量就是进入系统的质量流所携带的能量，以及辅助设备的驱动能量。离开系统的能量就是离开系统的质量流所携带的能量，以及通过蒸汽发生器表面传递给环境的能量。
Efficiency is the ratio of energy output to energy input, expressed as a percentage:
EF100Output,%(2-1)
InputWhen input is defined as the total energy of combustion available from the fuel, the resulting efficiency is commonly referred to as fuel efficiency.效率为输出能量和输入能量的比值，以百分数的形式表示：
EF100Output,%(2-1)
Input 当输入能量定义为燃料释放的所有能量时，所得的效率通常称为燃料效率。
2.7.1 Efficiency-energy balance method
In the energy balance method, the energy closure losses and credits are used to calculate efficiency.The energy balance method is the preferred method for
29-28 determining efficiency.It is usually more accurate than the input-output method because errors impact the losses and credits rather than the total energy.For example, if the total losses and credits are 10% of the total input, a 1% measurement error would result in only a 0.1% error in efficiency, where a 1% error in measuring fuel flow results in a 1% error in efficiency.Another major advantage to the energy balance method is that reasons for variations in efficiency from
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one test to the next can be identified.Also, it is readily possible to correct the efficiency to reference or contract conditions for deviations from test conditions such as the fuel analysis.2.7.1 效率-能量平衡法（反平衡法）
在能量平衡法中，采用能量损失和外来热量来计算效率。能量平衡法是确定效率的首选方法。因为测量误差仅影响着各项损失而不影响总能量，所以它一般情况下比输入－输出法更精确。例如：如总损失占总输入能量的10%，则1%的测量误差仅会导致0.1%的效率误差，而在测量燃料流量中1%的误差将会导致效率的1%的误差。能量平衡法的另一个优点就是可以确认两次效率测试结果不同的原因，另外，对于诸如燃料分析数据等试验条件的变化，该方法可以容易的将效率修正到基准工况或保证工况。
2.7.2 Efficiency-Input-Output method
Efficiency calculated by the input-output method is based upon measuring the fuel flow and steam generator fluid side conditions necessary to calculate output.The uncertainty of efficiency calculated by the input-output method is directly proportional to the uncertainty of determining the fuel flow, a respective fuel analysis, and steam generator output.Therefore, to obtain reliable results, extreme care must be taken to determine these items accurately.教材40页（第2章结束）
2.7.2 效率-输入-输出法（正平衡法）
根据输入-输出法计算的效率是基于测定燃料量和计算输出能量所必需的锅炉汽水侧参数。该方法计算的效率的不确定度直接与燃料测量、样本燃料分析和锅炉输出能量求取等的不确定度成正比。所以，要获得可靠的结果，在精确测量上述各项时必须格外谨慎。
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第二篇：热能与动力工程专业英语翻译Ch 01 教案
1.3 传热学基础
传热学是一门研究在存在温差的物体间发生能量传递的科学。热力学中将这种方式传递的能量定义为热量。传热学不仅可以解释热量传递是如何传递的，而且可以计算在特定条件下的传热速率。事实上，传热速率正是一个分析所期望的目标，它指明了传热学和热力学间的差别。热力学处理的是平衡状态下的系统，它可计算当系统从一个平衡状态过渡到另一个平衡状态时所需要的能量，但不能解决系统处于过渡过程的非平衡状态时能量变化的快慢程度。传热学提供了可用于计算传热速率的实验关联式，从而对热力学第一定律和第二定律进行补充。这里，我们介绍热量传递的三种方式和不同型式的换热器。1.3.1 Conduction heat transfer When a temperature gradient exists in a body, experience has shown that there is an energy transfer from the high-temperature region to the low-temperature region.We say that the energy is transferred by conduction and that the heat transfer rate per unit area is proportional to the normal temperature gradient: q/A~T/x.When the proportionality constant is inserted
qAT
(1-3)xWhere q is the heat transfer rate and T/x is the temperature gradient in the direction of heat flow.The positive constant λ is called the thermal conductivity of the material, and the minus sign is inserted so that the second principle of thermodynamics will be satisfied;i.e., heat must flow downhill on the temperature scale.Equation(1-3)is called Fourier’s law of heat conduction after the French mathematical physicist Joseph Fourier, who made very significant contributions to the analytical treatment of conduction heat transfer.It is important to note that Equation(1-3)is the defining equation for the thermal conductivity and that λhas the units of watts per meter per Celsius degree in a typical system of units in which the heat flow is expressed in watts.1.3.1 热传导
当物体内部存在温度梯度时，经验表明，就有能量从高温区向低温区传递。我们说，此时的能量通过传导进行传递，单位面积上的传热速率与法向温度梯度成正比，即q/A~T/x。引入比例系数，则有
qAT
(1-3)x其中q是热流量，T/x是热流方向上的温度梯度，正常数称为材料的导热系数。方程中插入的负号表示热传导过程应满足热力学第二定律，即热量必须沿温度降低的方向传递。式(1-3)称为傅立叶导热定律，以法国数理学家约瑟夫傅立叶的名字命名，傅立叶在导热的分析处理方面做出了极其重大的贡献。值得注意的是，式(1-3)也是导热系数的定义式，在典型的单位体系中，当热流量q的单位为W时，的单位为W/(m℃)。
1.3.2 Convection heat transfer
It is well known that a hot plate of metal will cool faster when placed in front of a fan then when exposed to still air.We say that heat is convected away;and we call the process convection heat transfer.The term convection provides the reader with an intuitive notion concerning the heat-transfer process;however, this intuitive notion must be expanded to enable one to arrive at anything like an adequate analytical treatment of the problem.For example, we know that the velocity at which the air blows over the hot plate obviously influences the heat transfer rate.But does it influence the cooling in a linear way;i.e., if the velocity is doubled, will the heat transfer double? We should suspect that the heat transfer rate must be different if we cooled the plate with water instead of air, but, again, how much difference would there be? These questions may be answered with the aid of some rather basic analyses.For now, we sketch the physical mechanism of convection heat transfer and show its relation to the conduction process.图1-8 对流换热
1.3.2 对流换热
众所周知，与热金属板放置在静止的空气中相比，放置在转动的风扇前的热金属板会更快地冷却。我们说热量通过对流进行传递，称此类换热过程为对流换热。对流这个术语给读者提供了有关传热过程的直观概念，然而，必须扩展这种直观概念，使我们可以达到对某一问题进行充分的分析和处理。例如，我们知道流过热平板的空气速度会明显影响其传热量，但它是以线性方式影响冷却的吗？即如果速度增加一倍，传热量也会增加一倍吗？我们猜想，如果用水代替空气冷却热平板，传热量可能有所不同，但是，二者的差异会有多少呢？这些问题在了解一些非常基本的分析后，可得以回答。现在，我们来简要描述对流换热的物理机理，并且说明它和传导过程的联系。
图1-8
Consider the heat transfer plate shown in Fig.1-8.The temperature of the plate is Tw and the temperature of the fluid is T∞.The velocity of the flow will appear as shown, being reduced to zero at the plate as a result of viscous action.Since the velocity of the fluid layer at the wall will be zero, the heat must be transferred only by conduction at that point.Thus we might compute the
教材12页
heat transfer, using Equation(1-3), with the thermal conductivity of the fluid and the fluid temperature gradient at the wall.Why, then, if the heat flows by conduction in this layer, do we speak of convection heat transfer and need to consider the velocity of the fluid? The answer is that the temperature gradient is dependent on the rate at which the fluid carries the heat away;a high velocity produces a large temperature gradient, and so on.Thus the temperature gradient at the wall depends on the flow field, and we must develop in our later analysis an expression relating the two quantities.Nevertheless, it must be remembered that the physical mechanism of heat transfer at the wall is a conduction process.被加热的平板如图1-8所示，平板的温度为Tw，流体的温度为T∞。速度分布如图所示，受黏性作用，平板上的速度减小为零。因为壁面处流动薄层的速度为零，因此，在该点上热量只能以导热方式传递。因此，可以利用式(1-3)，以及壁面上的流体导热系数和温度梯度来计算传热量。如果热量在该层经导热传递，那么，为什么我们要谈及对流换热以及需要考虑流体速度的影响呢？答案是，温度梯度依赖于流体带走热量的速度，较高的流速将产生较大的温度梯度。因此，壁面上的温度梯度依赖于流场的变化，在以后的分析中，我们将建立这二者间的关系。然而，必须记住，壁面上传热的物理机理是一导热过程。
To express the overall effect of convection.We use Newton’s law of cooling:
qhA(TwT)
(1-4)Here the heat-transfer rate is related to the overall temperature difference between the wall and fluid and the surface area A.The quantity h is called the convection of heat-transfer coefficient, and Equation(1-4)is the defining equation.An analytical calculation of h may be made for some systems.For complex situations it must be determined experimentally.From Equation(1-4)we note that the units of h are in watts per square meter per Celsius degree when the heat flow is in watts.为描述对流换热的整体效应，应用牛顿冷却定律
qhA(TwT)
(1-4)这里，热流量与壁面和流体间的整体温度差以及表面积A有关。参数h称为对流换热系数，式(1-4)是其定义式。对某些传热过程，可获得h的分析表达式，而复杂情形下的传热系数必须通过实验研究来确定。式(1-4)表明，当热流量的单位为W时，h的单位为W/(m2℃)。
If a heat plate were exposed to ambient room air without an external source of motion, a movement of the air would be experienced as a result of the density gradients near the plate.We call this natural, or free, convection as opposed to forced convection, which is experienced in the case of the fan blowing air over a plate.Boiling and condensation phenomena are also grouped under the general subject of convection heat transfer.如果将热平板置于没有外部风源的房间空气中，平板附近的密度梯度将造成空气运动。我们称此换热过程为自然对流，以区别于风扇吹扫平板表面时形成的强制对流。沸腾和凝结现象也属于对流换热的范畴。
1.3.3 Radiation heat transfer In contrast to the mechanisms of conduction and convection, where energy transfer through a material medium is involved, heat may also be transferred through regions where a perfect vacuum exists.The mechanism in this case is electromagnetic radiation.We shall limit our discussion to electromagnetic radiation which is propagated as a result of a temperature difference;this is called thermal radiation.1.3.3 辐射换热
对于导热和对流换热，其热量传递需要介质才得以进行，与此不同的是，热量也可以在完全真空中传递，其传热机理是电磁辐射。我们将讨论限定在由温差导致的电磁辐射，即所谓的热辐射。
Thermodynamic considerations show that an ideal thermal radiator, or blackbody, will emit energy at a rate proportional to the fourth power of the absolute temperature of the body and directly proportional to its surface area.Thus
qemittedAT
4(1-5
Where is σ the proportionality constant and is called the Stefan-Boltzmann constant with the value of 5.669×10-8W/(m2·K4).Equation(1-5)is called the Stefan-Boltzmann law of thermal radiation, and it applied only to blackbodies.It is important to note that this equation is valid only for thermal radiation;other types of electromagnetic radiation may not be treated so simply.热力学研究表明，对于理想的热辐射体或黑体，其辐射力正比于物体绝对温度的四次方及其表面积，因此有
qemittedAT4
(1-5)式中，为比例系数，称为斯忒藩－玻耳兹曼常数，其值为5.669×10-8 W/(m2·K4)。式(1-5)称为热辐射的斯忒藩－玻耳兹曼定律，该式仅适用于黑体。值得注意的是，该表达式仅适用于热辐射，其它类型的电磁辐射要比该式复杂得多。
Equation(1-5)governs only relation emitted by a blackbody.The net radiant exchange between two surfaces will be proportional to the difference in absolute temperatures to the fourth power;i.e.教材13页
式(1-5)只能用于确定单个黑体的辐射能。两个表面间的净辐射换热量与其绝对温度四次方的差成正比，即
qnet exchangeA(T14T24)
(1-6)We have mentioned that a blackbody is a radiate energy according to the T4 law.We call such a body black because black surface, such as a piece of metal converted with carbon black, approximate this type of behavior.Other types of surfaces, such as a glossy painted surface or a polished metal plate, do not radiate as much energy as the blackbody;however, the total radiation emitted by these bodies will generally follow the T41 proportionality.To take account of the “gray” nature of such surfaces we introduce another factor into Equation(1-5), called the emissivity ε, which relates the radiation of the “gray” surface to that of an ideal black surface.In addition, we must take into account the fact that not all the radiation leaving one surface will reach the other surface since electromagnetic radiation travels in straight lines and some will be lost to the surroundings.We therefore introduce two new factors in Equation(1-5)to take into account both situations, so that
qFFGA(T14T24)
(1-7)Where Fε is an emissivity function and FG is a geometric “view factor” function.It is important to alter the reader at this time, however, to the fact that these functions usually are not independent of one another as indicated in equation(1-7).我们已经提到，黑体是按四次方定律辐射能量的物体。因其黑色的表面我们称之为黑体，如覆盖炭黑的金属片，就近似具有这种辐射特性。其它类型的表面，如有光泽的漆面或抛光的金属板，并不具有黑体那样大的辐射力，然而，这些物体的辐射力仍大致与T14成正比。为了考虑这些表面的“灰”特性，在式(1-5)引入另一个参数，称为发射率ε，发射率将这些“灰”表面的辐射与理想黑体的表面辐射联系起来。此外，我们必须考虑这样一个事实，并非一个表面发出的所有辐射都可以到达到另一个表面，因为电磁辐射是沿直线传播的，将有部分能量散失到周围环境中。因此，考虑到这两种情况，式(1-5)引入另外两个新的参数，则有
44qFFA(TT)
(1-7)G1
2式中，Fε是发射率函数，FG是几何角系数。此时，值得提醒读者的是，式(1-7)中的这两个函数通常并不是相互独立的。
1.3.4 Types of heat exchangers
The simplest type of heat exchanger consists of two concentric pipes of different diameters, called the double-pipe heat exchanger.One fluid in a double pipe heat exchanger flows through the smaller pipe while the other fluid flows through the annular [环形] space between the two pipes.Two types of flow arrangement are possible in a double pipe heat exchanger;in parallel flow, both the hot and cold fluid enters the heat exchanger at the same end and move in the same direction.In counter flow, on the other hand, the hot and cold fluids enter the heat exchanger at opposite ends and flow in opposite directions.1.3.4 换热器的类型
最简单的换热器是由两个不同直径的同心圆管组成，称为套管式换热器。套管换热器中的一种流体流经细管，另一种流体流经两管间的环形区域。套管换热器中包括两种不同类型的流动方式：一种为顺流，即冷、热流体从同一端进入换热器，并沿同一方向流动；另一种为逆流，即冷、热流体从相反的两端进入换热器，且沿相反方向流动。
Another type of heat exchanger, which is specifically designed to realize a large heat transfer surface area per unit volume, is the compact heat exchanger.The ratio of the heat transfer surface area of a heat exchanger to its volume is called the area density β.A heat exchanger with β>700m2/m3 is classified as being compact.Example of compact heat exchangers are car radiators(β≈1000m2/m3), glass ceramic gas turbine heat exchangers(β≈6000m2/m3), the regenerator of a Stifling engine(β≈15,000m2/m3), and human lung(β≈20,000m2/m3).Compact heat exchangers enable us to achieve high heat transfer rates between two fluids in a small volume, and they are commonly used in applications with strict limitations on the weight and volume of heat exchangers.另一类换热器，被专门设计成单位体积内有很大的换热面积，称为紧凑式换热器。换热器的换热面积与其体积之比称为面积密度β。β＞700 m2/m3的换热器归为紧凑式换热器。例如汽车散热器（β≈1000 m2/m3）、燃气轮机中的玻璃陶瓷换热器（β≈6000 m2/m3）、斯特林机的回热器（β≈15,000 m2/m3）以及人的肺部（β≈20,000 m2/m3）。紧凑式换热器能实现小容积内两种流体的高换热率，通常用于换热器重量和容积受到严格限制的场合。
The large surface area in compact heat exchangers is obtained by attaching closely spaced thin plate or corrugated fins to the walls separating the two fluids.Compact heat exchangers are commonly used in gas-to-gas and gas-to-liquid(or liquid-to-gas)heat exchangers to counteract the low heat transfer coefficient associated with gas flow with increased surface area.In a car radiator, which is a water-to-air compact heat exchanger, for example, it is no surprise
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that fins are attached to the air side of the tube surface.图1-9 紧凑式换热器通过在分离两种流体的壁面上附加间隔紧密的薄板或波纹翅片来扩展其表面。紧凑式换热器通常用于气－气和气－液（或液－气）换热器，通过增加传热面积来抵消气侧低传热系数所带来的影响。例如，汽车散热器是水－气紧凑式换热器的典型例子，通常管子气侧表面装有翅片。
Perhaps the most common type of heat exchanger in industrial applications is the shell-and-tube heat exchanger, shown in Fig.1-9.Shell-and-tube heat exchangers contain a large number of tubes(sometimes several hundred)packed in a shell with their axes parallel to that of the shell.Heat transfer takes place as one fluid flows inside the tube while the other fluid flows outside the tubes through the shell.Baffles are commonly placed in the shell to force the shell-side fluid to flow across the shell to enhance heat transfer and to maintain uniform spacing between the tubes.Despite their widespread use, shell-and-tube heat exchangers are not suitable for use in automotive and aircraft applications because of their relatively large size and weight.Note that the tubes in a shell-and-tube heat exchanger open to some large flow areas called headers at both ends of the shell, where the tube-side fluid accumulates before entering the tubes and after leaving them.图1-9 管-壳式换热器简图
工业应用中最常见的换热器也许是管壳式换热器，如图1-9所示。管壳式换热器外壳里封装有大量的管束（有时为数百根），其轴线与外壳轴线平行。当一种流体在管内流动，另一种流体在管外流动并穿过壳体时，就进行了热交换。壳内通常布置有挡板，用于使壳侧流体沿壳流动以强化传热，并保持均匀的管间距。虽然管壳式换热器应用广泛，但因其相对较大的尺寸和重量，因而并不适用于汽车和航空器领域。注意，管壳式换热器的管束两侧开口处的较大流动区域称为封头，它位于壳体两端，管侧流体流入、流出管子前后都在此汇集。
Shell-and-tube heat exchangers are further classified according to the number of shell and tube passes involved.Heat exchangers in which all the tubes make one U-turn in the shell, for example, are called one-shell-pass and two-tube-passes heat exchangers.Likewise, a heat exchanger that involves two passes in the shell and four passes in the tubes is called a two-shell-passes and four-tube-passes heat exchanger.管壳式换热器依据所含管程和壳程的数目可进一步分类。例如，换热器壳内的所有管束采用一个U型布置的称为单壳程双管程换热器（1-2型换热器）。同样地，含有双壳程和四管程的换热器叫做双壳程－四管程型换热器（2-4型换热器）。
An innovative type of heat exchanger that has found widespread use is the plate and frame(or just plate)heat exchangers, which consist of a series of plates with corrugated flat flow passages.The hot and cold fluids flow in alternate passages and thus each cold fluid stream is surrounded by two hot fluid streams, resulting in very effective heat transfer.Also, plate heat exchangers can grow with increasing demand for heat transfer by simply mounting more plates.They are well suited for liquid-to-liquid heat exchange application provided that the hot and cold fluid streams are at about the same pressure.一种广泛使用的新型换热器是板翅式（或板式）换热器，它由一系列平板组成，并形成波纹状的流动通道。冷、热流体在间隔的每个通道中流动，每一股冷流体被两股热流体所包围，因此换热效果非常好。此外，板式换热器可通过简单添加更多的平板来满足增强换热的需求。该类型换热器非常适用于液－液式换热场合，但需要冷、热液流的压强大致相等。
Another type of heat exchanger that involves the alternate passage of the hot and cold fluid stream through the same flow area is the regenerative heat exchanger.The static-type regenerative heat exchanger is basically a porous mass that has a large heat storage capacity, such as a ceramic wire mesh.Hot and cold fluid to the matrix of the regenerator during the flow of the hot fluid, and from the matrix to the cold fluid during the flow of the cold fluid.Thus, the matrix serves as a temporary heat storage medium.The dynamic-type regenerator involves a rotating drum and continuous flow of the hot and cold fluid through different portions of the drum so that any portion of the drum passes periodically through the hot
教材15页 stream, storing heat, and then through the cold stream, rejecting this stored heat.Again the drum serves as the medium to transport the heat from the hot to the cold fluid stream.另一类冷、热流体交替通过同一流动面积的换热器为蓄热式换热器。静态型蓄热式换热器基本上由多孔介质组成，其热容量大，如陶瓷铁丝网。冷、热流体交替地流经这些多孔介质，热量先由流过的高温流体传递到换热器的换热基体，再由基体传递给接着流过的低温流体。因此，基体充当了临时储热介质的作用。动态型蓄热式换热器内有转筒，冷、热流体连续流动通过转筒的不同部分，使得转筒的任一部分周期性地通过热流体，存储热量，再通过冷流体，释放存储的热量。转筒作为热量从热流体传递到冷流体的媒介。
Heat exchangers are often given specific names to reflect the specific application for which they are used.For example, a condenser is a heat exchanger in which one of the fluids is cooled and condenses as it flows through the heat exchanger.A boiler is another heat exchanger that transfers heat from the hot fluid(flue gas)to the surrounding space by radiation.教材16页
换热器往往被赋予特定的名称来反映它们的特定用途。例如，冷凝器是流体流经它时会发生冷却凝结的一种换热器。锅炉是另一类换热器，流体在其内吸热并汽化。空间辐射器是以辐射方式将热流体的热量传递到周围空间的换热器。
第三篇：热能与动力工程专业介绍
热能与动力工程专业介绍
（工学、能源动力类、专业代码：080501）
一、专业简介
（一）培养目标
本专业以能源工业为特色，培养德智体美全面发展，具有较扎实的理论基础和专业技术知识，较好的综合素质与较强的工程技术应用能力，受到工程师的基本训练。
热力发电厂方向，主要从事热能与动力工程设备和系统的设计、运行、管理、技术研究与开发，节能等方面的应用型高级技术人才。
风能与动力工程方向，主要从事现代风力发电场的运行、管理、规划、设计与施工、风能资源测量与评估等方面的应用型高级技术人才。
（二）专业内容
热力发电厂方向，是将常规能源（化石燃料、天然气、石油）在锅炉内燃烧产生的化学能转化成热能，通过工质推动热动力设备做功，将热能转化为机械能，带动发电机将机械能转化为电能。
风能与动力工程方向，是将空气的动能通过风力机转化成机械能，带动风力发电机将机械能转化为电能。
（三）专业特色
本专业以能源工业为特色，认真贯彻党的教育方针，坚持专业建设以社会需求为导向的办学思想，凸显能源资源特色，以应用型人才培养为目标，构建知识、能力与创新的课程体系，为宁夏及周边区域能源资源建设提供所需的应用型人力资源。
二、主干课程
热力发电厂方向：工程热物理、热能动力
主要课程：流体力学、工程热力学、传热学、电工电子技术、电厂锅炉、汽轮机原理、热力发电厂、换热器设计、理论力学、材料力学、热工自动化仪表、泵与风机、机械设计基础等。
风能与动力工程方向：风能动力
主要课程：流体力学、空气动力学、电工电子技术，理论力学、材料力学、自动控制理论，风力机原理，风电机组设计制造，风电场电气工程、风资源测量与评估、电机学、风力发电场、机械设计基础等。
三、就业方向
毕业生可在大型能源企业和相关公司，如热力发电厂、风力发电场、汽轮机厂、锅炉制造厂、风力机设备制造厂等，从事系统的设计、运行、管理、技术研究与开发，新能源利用等方面的工作。
第四篇：热能与动力工程专业求职信
热能与动力工程专业求职信1
尊敬的公司领导：
您好！
非常感谢您在百忙之中翻阅我的自荐表。
毕业在即，贵公司良好的声誉和工作环境深深吸引了我，我由衷地希望能够成为你们的一员，共创辉煌。
在校期间，我始终把自身素质的培养放在第一位，努力学习掌握科学文化知识和专业技能，学习成绩和综合积分居专业上游。以良好的成绩，一次性的'通过了所有课程。在外语方面，通过了日语国家四级和日语国际二级，自修了大众英语，已达初级水平。在计算机应用方面，熟练掌握了cad制图、office办公软件等，另对internet有一定的了解和认识。另外，由于个人兴趣，自学了管理、营销、金融等方面的知识。
学习之余，为锻炼自己多方面的能力，积极参加了各种社会实践活动，每个假期都积极参加了社会实践，对我国社会状况和工业状况有了初步的了解，下厂实习的时间多观察，勤思考加强了理论同实际的结合，为适应时代要求，参加了机动车驾驶班，并拿到了机动车驾驶c照，此外，还参加了很多的公益活动。曾无偿献血一次，在九冬会期间，报名参加志愿者为九冬会献了一份微薄之力。
尊敬的公司领导，如果您选择了我，我会一步一个脚印，真真实实地走好每一步，用实际行动来证明您的选择是英明的。
衷心希望贵公司给我一个发展的机会！
祝愿贵公司事业蒸蒸日上！
热能与动力工程专业求职信2
尊敬的领导：
您好!
我是吉林大学汽车工程学院热能与动力工程专业97届的一名学生，即将面临毕业。
吉林大学南岭校区是我国著名的汽车、机械等人才的重点培养基地，具有悠久的历史和优良的传统，并且素以治学严谨、育人有方而著称;吉林大学南岭校区汽车学院则被誉为我国汽车工业的摇篮。在这样的学习环境下，无论是在知识能力，还是在个人素质修养方面，我都受益匪浅。
四年来，在师友的严格教益及个人的努力下，我具备了扎实的专业基础知识，系统地掌握了热能与动力工程专业的有关理论;熟悉涉外工作常用礼仪;具备较好的英语听、说、读、写、译等能力;能熟练操作计算机办公软件。同时，我利用课余时间广泛地涉猎了大量书籍，不但充实了自己，也培养了自己多方面的技能。更重要的是，严谨的学风和端正的学习态度塑造了我朴实、稳重、创新的性格特点。
此外，我还积极地参加各种社会活动，抓住每一个机会，锻炼自己。大学四年，我深深地感受到，与优秀学生共事，使我在竞争中获益;向实际困难挑战，让我在挫折中成长。前辈们教我勤奋、尽责、善良、正直;吉林大学培养了我实事求是、开拓进取的作风。我热爱贵单位所从事的事业，殷切地期望能够在您的领导下，为这一光荣的事业添砖加瓦;并且在实践中不断学习、进步。
收笔之际，郑重地提一个小小的要求：无论您是否选择我，尊敬的领导，希望您能够接受我诚恳的谢意!祝愿贵单位事业蒸蒸日上!
此致
敬礼!
求职者：
第五篇：热能与动力工程专业之我见
热能与动力工程专业之我见
一 专业概述
本专业培养具备热能工程、传热学、流体力学、动力机械、动力工程等方面基础知识，能在国民经济和部门，从事动力机械(如热力发动机、流体机械、水力机械)的动力工程(如热电厂工程、水电动力工程、制冷及低温工程、空调工程)的设计、制造、运行、管理、实验研究和安装、开发、营销等方面的高级工程技术人才。
热能与动力工程专业可分成以下三个专业方向：
1.以热能转换与利用系统为主的热能动力工程（能源利用）；
2.以内燃机及其驱动系统为主的热力发动机及汽车工程方向（发动机）；
3.以电能、热能转换为机械功为主的流体机械与制冷低温工程方向（制冷、空调）；
培养要求
本专业主要学习动力工程及工程热物理的基础理论，学习各种能量转换及有效利用的理论和技术，受到现代动力工程师的基本训练；具有进行动力机械与热工设备设计、运行、实验研究的基本能力。
毕业生应获得以下几方面的知识和能力：
1.具有较扎实的自然科学基础，较好的人文、艺术和社会科学基础及正确运用本国语言、文字的表达能力；
2.较系统地掌握本专业领域宽广的技术理论基础知识，主要包括工程力学、机械学、工程热物理、流体力学、电工与电子学、控制理论、市场经济及企业管理等基础知识；
3.获得本专业领域的工程实践训练，具有较强的计算机和外语应用能力；
4.具有本专业领域内某个专业方向所必要的专业知识，了解其科学前沿及发展趋势；
5.具有较强的自学能力、创新意识和较高的综合素质。
培养目标
本专业主要培养能源转换与利用和热力环境保护领域具有扎实的理论基础，较强的实践、适应和创新能力，较高的道德素质和文化素质的高级人才，以满足社会对该能源动力学科领域的科研、设计、教学、工程技术、经营管理等各方面的人才需求。学生应具备宽广的自然科学、人文和社会科学知识，热学、力学、电学、机械、自动控制、系统工程等宽厚理论基础、热能动力工程专业知识和实践能力，掌握计算机应用与自动控制技术方面的知识。毕业生能从事能源与动力工程及相关方面的研究、教学、开发、制造、安装、检修、策划、管理和营销等工作。
我校提出卓越工程师计划，旨在培养理论基础扎实，有较强的研究能力，技术过硬，有很强的动手能力的复合型人才。
主干学科
动力工程与工程热物理、机械工程
主要课程
工程力学、机械设计基础、电工与电子技术、工程热力学、流体力学、传热
学、控制理论、测试技术等主要实践性教学环节：包括军训、金工、电工、电子实习、认识实习、生产实习、社会实践、课程设计、毕业设计(论文)等，一般应安排40周以上。
主要专业实验
传热学实验、工程热力学实验、动力工程测试技术实验等
知识结构要求
工具性知识：比较系统地掌握一门外语，掌握外文科技写作知识。掌握计算机软、硬件技术的基本知识，具有在本专业与相关领域的计算机应用与开发能力；掌握通过网络获取信息的知识、方法与工具。能够进行中外文文献检索。
自然科学知识：掌握高等数学、大学物理、工程化学、生命科学、环境科学等方面的知识。
学科技术基础知识：掌握工程制图、工程数学、理论力学、材料力学、机械原理、机械设计基础、金属工艺学、电工学、CAE有限元设计、液压传动、电子技术基础、工程流体力学、工程热力学、传热学、计算机原理与应用、自动控制原理等方面的知识(对水利水电动力工程方向，工程热力学、传热学知识要求可适当降低)。
专业知识：根据本专业人才培养目标和培养规格，因专业方向的不同而有所差别。
（1）热能转换系统工程(能源利用)主要掌握热能与动力测试技术、锅炉原理、汽轮机原理、能源概论、燃烧污染与环境、动力机械设计、热力发电厂、热工自动控制、传热传质数值计算、流体机械、内燃机设计等知识。
（2）热力发动机及汽车工程方向（发动机）掌握内燃机（或透平机）原理、结构，设计，测试，燃料和燃烧，热力发动机排放与环境工程，能源工程概论，内燃机电子控制，热力发动机传热和热负荷，汽车工程概论、汽车理论、汽车制造工艺学等方面的知识。
（3）制冷低温工程与流体机械方向（制冷空调）掌握制冷、低温原理、人工环境自动化、暖通空调系统、低温技术学、热工过程自动化、流体机械原理、流体机械系统仿真与控制等方面的知识。使学生掌握该方向所涉及的制冷空调系统、低温系统，制冷空调与低温各种设备和装置，各种轴流式、离心式压缩机和各种容积式压缩机的基本理论和知识。
也就是说，本专业学生应具有如下知识和能力，并根据培养规格的不同而有所侧重：
（1）具有较扎实的自然科学基础，熟练掌握高等数学、工程数学、大学物理、工程化学等基础性课程的基本理论和应用方法；具有较好的人文、艺术和社会科学基础及正确应用本国语言、文字的表达能力。
（2）掌握一门外国语，具有较好的听、说、读、写能力，能较顺利地阅读本专业的外文书籍和资料。若外语为英语应达到国家四级以上水平（含四级）。
（3）系统地掌握本专业必需的技术基础理论，主要包括力学理论（理论力学、材料力学、流体力学），热学理论（热力学、传热学等），机械设计基本理论，电工与电子基本理论，自动控制理论，能源动力工程基础理论等。
（4）熟悉本专业领域内1～2个专业方向或有关方面的专业知识，了解其学
科前沿和发展趋势。
（5）具有本专业必需的制图、计算、测试、调研、查阅文献和基本工艺、操作、运行等基本技能。
（6）具有一定计算机相关知识和较强的计算机应用能力，较熟练使用计算机工具，解决工程中的有关问题。
（7）具有较强的自学能力、分析能力和创新意识。
二 个人学习方向
本人倾向能源利用和发动机这两个方向
全球资源紧张，环境持续恶化，为了保证人们越来越高的物质享受，我们必须提高能源的利用率，同时寻找新的替代能源——节源、开流——节源是开流的缓冲阶段，为开流争取时间。所以个人倾向能源利用这一方向。
发动机可为能源利用的研究提供资料，是两个相辅相成的专业方向。
三 学习计划
拟在大一完成上述工具性知识的学习以及初步了解专业理论知识和发展动向 拟在大二完成专业理论知识的学习，熟练专业方向所需的技能，具有初步理论论证、设计能力
拟在大三深入专业理论知识，同时具备较强的动手操作能力
拟在大四具备独立的研究能力及熟练的专业实践能力，有较强的社会生存能力
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