第一篇：熱能與動(dòng)力工程專業(yè)英語翻譯Ch 02 教案

Chapter 2 Boiler

第二章

鍋爐

Air heater 空預(yù)器 Anchor 支座，固定 Anhydrous ammonia 無水氨 Anthracite 無煙煤 Atomized 霧化 Austenitic 奧氏體鋼 Auxialiary 輔助機(jī)械 Axis 軸 Bagasse 甘蔗渣 Bare tube 光管 Bark 樹皮 Beam 梁，橫梁 Bituminous coal 煙煤 Blade 葉片 Blast 鼓風(fēng) Blowdown 排污 Boiler 鍋爐 Bulk 大塊的

Burner zone 燃燒器區(qū)域 Butane 丁烷 Calcination 煅燒 Capacity 出力 Carbon steel 碳鋼 Cerium 鈰 Chromium 鉻 床鍋爐 Coal char 煤焦

Cogenerator 熱點(diǎn)聯(lián)產(chǎn)機(jī)組 Combustion 燃燒

Dwell time 保留時(shí)間 Economizer 省煤器 Embrittlement 脆性，脆化

29-1

Commissioning 試運(yùn)行 Compressor 壓縮機(jī)、壓氣機(jī) Condenser 凝汽器 Containment 反應(yīng)堆安全殼 Convection 對(duì)流 Coolant 制冷劑 Coordinated 坐標(biāo)，定位 Corten低合金耐腐蝕鋼 Counterflow 逆流（換熱器）Creep strength 蠕變強(qiáng)度 Criterion 標(biāo)準(zhǔn)

Critical pressure 臨界壓力 Culm 煤屑

Cyclone furnace 旋風(fēng)爐 Debris 殘骸、有機(jī)殘留物 Decane 癸烷 Decay 分解

Deposited 沉積，沉淀的 Deterioration 惡化 Diesel oil 柴油 Differential 差動(dòng)，微分 Distillate 餾出物 Distortion 變形

Division wall 分隔墻，雙面水冷壁 Drainage 疏水

Circulating fluidized bed CFB 循環(huán)流化Drum 汽包 Equalization 均衡，平衡 Erosive 侵蝕的，腐蝕的 Ethane 乙烷 Evaluate 評(píng)估，評(píng)價(jià) Evaporate 蒸發(fā) Excess air 過量空氣 Extended surface 擴(kuò)展受熱面 Fatigue 疲勞 Feedwater 給誰 Ferrite 鐵素體 Fin 鰭片，肋片 Flange 法蘭 Flue gas 煙氣 Fouling 沾污 Furnace 爐膛 Generator 發(fā)電機(jī) Geological 地質(zhì)的 Girth 環(huán)形 Govern 控制、調(diào)節(jié) Gravity 重力 Header 聯(lián)箱，集箱 Helical 螺旋狀的 Helium 氦

Heterogeneous 不均勻的 Hopper 斗，料斗 Husk 殼，外殼

Hydraulic 水力的，液壓的 Ignite 點(diǎn)火 Impurity 雜質(zhì) Inert 惰性

Inferior 低級(jí)的，劣質(zhì)的 Ingredients 成分

Ingress進(jìn)口，入口 In-line 順列 Inorganic 無機(jī)的 Ion 離子 Jurisdiction 權(quán)限 Lignite 褐煤 Lime 石灰 Limestone 石灰石 Low alloy 低合金鋼 Low-volatile 低揮發(fā)分的 Margin 裕量，安全系數(shù) Matrix 矩陣 Membrane 膜 Methane 甲烷 Mill 磨煤機(jī) Molecule 分子 Molten 熔化 Nitric oxide 氮氧化物 Nonpressure 非承壓的 Nontoxic 無毒的 Organisms 有機(jī)體 Oxidation 氧化 Peat 泥煤

Pendants superheat platen 懸吊式屏式過熱器 Pentane 戊烷

Petrochemical 石油化工制品 Petroleum 石油制品

Plasma spray coating 等離子噴涂Platen 屏 Polymer 聚合物 Pores 氣孔，小孔 Porosity多空的

29-2

Potassium 鉀

Prandtl numbers 普朗特?cái)?shù) Prefabricated 預(yù)制的 Premium fuel 優(yōu)質(zhì)燃料 Pressure loss 壓力損失 Primary air 一次風(fēng) Propane 丙烷

Proximate analysis 工業(yè)分析 Pulp 紙漿 Pyrites 黃鐵礦 Radius 半徑，范圍 Rare earth element 稀土元素 Recuperator 間壁式換熱器 Regenerator 回?zé)崞鳎顭崞鱎egulate 控制，調(diào)節(jié) Repercussions 反應(yīng) Reservoirs 儲(chǔ)氣罐 Residuale fuel oil 渣油 Resonant 共振 Retract縮回

Reynolds number 雷諾數(shù) Rigid 剛性的，緊密地 Rollers 輥?zhàn)?Scale 水垢，Seal 密封 Sedimentary 沉積 Serpentine tube 蛇形管 Shale 頁巖 Silica 二氧化硅 Silt 淤泥 Single-phase 單相 Skin casing 外護(hù)板 Slag 結(jié)渣

Slurry 水煤漿 Sodium 鈉 Solvents 溶劑 Sootblower 吹灰器 Sour gas 含硫氣體 Specification 規(guī)格 Stable ignition 穩(wěn)定著火 Stanton number 斯坦頓數(shù) Saturated 飽和的 Straw 稻草

Steam line blowing 蒸汽管路吹灰 Steams 莖，桿

Stress corrosion 應(yīng)力腐蝕 Structural formula 結(jié)構(gòu)式 Stud 雙頭螺栓

Subbituminous 貧煤，次煙煤 Suction 真空，負(fù)壓 Sulphur 硫 Superheater 過熱器 Swamp 沼澤 Sweet gas 無硫氣

Switchgear 配電裝置，開關(guān)裝置 Temperature-entropy 溫熵圖 Tenacious 黏的 Thermodynamics 熱力學(xué) Tube bundles 管束 Tubular 管狀的 Turbine 汽輪機(jī) Velocity 速度

Vertical spidle mill 中速磨，立軸磨Vessel 容器 Viscosity 黏度

Volumetric expansion 體膨脹

29-3

Vulnerable 易損的，薄弱的 Wear磨損 Welded 焊接 Wingwall屏式凝渣管 Yttrim 釔

Abbreviations AFBC 常壓流化床燃燒 AFCO 燃料自動(dòng)切斷 AFWC 給水自動(dòng)切斷 ASME 美國(guó)機(jī)械工程師協(xié)會(huì) ATM 標(biāo)準(zhǔn)大氣壓 BFP 鍋爐給水泵 BUT 按鈕 BWC鍋爐水濃度 BYP 旁路

CFBB 循環(huán)流化床鍋爐 MCR 最大連續(xù)蒸發(fā)量 DAS 數(shù)據(jù)采集系統(tǒng)

2.1 Introduction

DEH 數(shù)字電液系統(tǒng) DNB 偏離核態(tài)沸騰 FDF 送風(fēng)機(jī) FGD 煙氣脫硫

FSSS 爐膛安全檢測(cè)保護(hù)系統(tǒng) HRB 回?zé)徨仩t IDF 引風(fēng)機(jī)

IGCC 整體煤氣化聯(lián)合循環(huán) LMTD 對(duì)數(shù)平均溫差 MFT 主燃料切斷 MUF 鍋爐補(bǔ)給水 NWL 正常水位 OFA 火上風(fēng)，燃盡風(fēng) PFBC 增壓流化床燃燒 SSC 刮板除渣機(jī) TGA 熱重分析儀 UBC 未燃燒 WFGD 濕法煙氣脫硫

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 簡(jiǎn)介SSC 鍋爐利用熱量使水轉(zhuǎn)變成蒸汽以進(jìn)行各種利用。其中主要是發(fā)電和工業(yè)供熱。由于蒸汽具有有利的參數(shù)和無毒特性，因此蒸汽作為一種關(guān)鍵的工質(zhì)（資源）被廣泛地應(yīng)用。蒸汽流量和運(yùn)行參數(shù)的變化很大：從某一過程里1000磅/小時(shí)（0.126kg/s）到大型電廠超過10×106

29-4 磅/小時(shí)（1260kg/s），壓力從一些加熱應(yīng)用的14.7磅/ in2（1.0135bar）212F（100℃）到先進(jìn)循環(huán)電廠的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.現(xiàn)代鍋爐可根據(jù)不同的標(biāo)準(zhǔn)分類。這些包括最終用途、燃燒方式、運(yùn)行壓力、燃料和循環(huán)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.大型中心電站的電站鍋爐主要用來發(fā)電。它們經(jīng)過優(yōu)化設(shè)計(jì)，可達(dá)到最高的熱效率。新機(jī)組的關(guān)鍵特性是利用再熱器提高整個(gè)循環(huán)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: 各種附加的系統(tǒng)也產(chǎn)生蒸汽用于發(fā)電及其他過程應(yīng)用。這些系統(tǒng)常常利用廉價(jià)或免費(fèi)燃料，聯(lián)合動(dòng)力循環(huán)和過程，以及余熱回收，以減少總費(fèi)用。這些例子包括：

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?xì)廨啓C(jī)聯(lián)合循環(huán)（CC）：先進(jìn)的燃?xì)廨啓C(jī)，將余熱鍋爐作為基本循環(huán)的一部分，以利用余熱并提高熱效率。

Integrated Gasification Combined Cycle(IGCC)adds a coal gasifier to the CC to reduce fuel cost and minimize airborne emissions.整體煤氣化聯(lián)合循環(huán)（IGCC）：在CC基礎(chǔ)上增加煤氣化爐，以降低燃料費(fèi)用并將污染排放降到最低。

Pressurized Fluidized-bed Combustion(PFBC)includes higher pressure combustion with gas cleaning and expansion of the combustion products through a gas turbine.增壓循環(huán)流化床燃燒（PFBC）：在更高壓力下燃燒，包括燃?xì)鈨艋约叭紵a(chǎn)物膨脹并通過燃?xì)廨啓C(jī)做功。

29-5 Blast furnace hood heat recovery generates steam using the waste heat from a blast furnace.高爐排煙熱量回收：利用高爐余熱產(chǎn)生蒸汽。

Solar steam generator uses concentrators to collect and concentrate solar radiation and generate steam.太陽能蒸汽發(fā)生器：利用集熱器收集太陽輻射熱產(chǎn)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頁 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 電站鍋爐的發(fā)展

現(xiàn)代660MW燃煤鍋爐有大約6000噸的壓力部件，其中包括500千米的受熱面管材，3.5千米連接管，和30000個(gè)管接頭焊口。這是經(jīng)過大約50年發(fā)展的成果，并形成了至今未變的基本概念，即煤粉在布置有蒸發(fā)管束的爐膛內(nèi)燃燒，然后煙氣通過對(duì)流過熱器和熱回收表面。蒸汽參數(shù)的提高，機(jī)組容量的增大及燃料燃燒特性改進(jìn)都要求在材料、制造技術(shù)和運(yùn)行程序上相應(yīng)發(fā)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.二戰(zhàn)后的一些年里，在電廠安裝鍋爐的數(shù)量多于汽輪機(jī)是很常見的，鍋爐提供蒸汽到母管然后到汽機(jī)。這種布置反應(yīng)了鍋爐的可用性低于汽輪機(jī)。四十年代后期，隨著鍋爐可用性的提高，鍋爐和汽機(jī)開始可以相互配套使用。這一變化使再熱變得可行，而且隨著高溫鋼材

29-6 可用性的提高，蒸汽參數(shù)不斷變化，達(dá)到了當(dāng)前的2400lbf/in2（165.5bar），568℃和568℃再熱的標(biāo)準(zhǔn)循環(huán)。為充分利用更高的蒸汽參數(shù)和獲得更大的經(jīng)濟(jì)性，在接下來的15年，機(jī)組容量又增加了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.電站設(shè)備一般向負(fù)責(zé)設(shè)計(jì)、制造、建設(shè)和調(diào)試的專業(yè)廠商購(gòu)得。同時(shí)生產(chǎn)廠商實(shí)施生產(chǎn)過程的發(fā)展，不斷修正設(shè)計(jì)方法，改變必要的運(yùn)行參數(shù)和容量, 從而形成新電廠的原型。雖然一些新的特性可以在安裝前進(jìn)行測(cè)試，但一個(gè)新設(shè)計(jì)鍋爐的真正測(cè)試是和汽輪發(fā)電機(jī)組配套運(yùn)行后進(jìn)行的。一個(gè)新的設(shè)計(jì)獲得商業(yè)成功需要通過電站在整個(gè)設(shè)計(jì)壽命中的使用來證明。因此，需要平衡考慮由效率提高、投資成本減少等帶來的直接經(jīng)濟(jì)效益，與新設(shè)計(jì)機(jī)組可能產(chǎn)生的可靠性低和需要大的改進(jìn)等風(fēng)險(xiǎn)。公用事業(yè)公司一般依靠發(fā)電需求購(gòu)買設(shè)備，并且最初可用性較低的影響不僅不能滿足負(fù)荷需求，還需要使用昂貴設(shè)備以彌補(bǔ)不足。因此，在對(duì)蒸汽循環(huán)及機(jī)組容量進(jìn)行較大改進(jìn)的時(shí)期，必須和廠商在設(shè)計(jì)、制造領(lǐng)域，以及運(yùn)行、維護(hù)技術(shù)領(lǐng)域密切合作，以保證經(jīng)濟(jì)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

教材26頁

29-7 furnaces and even solar energy.2.3 燃料及燃燒

大部分鍋爐以煤、天然氣和石油作為燃料。然而，在過去的幾十年里，至少在發(fā)電領(lǐng)域核能開始扮演一個(gè)主要角色。同樣，不斷增加的各種生物質(zhì)和工業(yè)副產(chǎn)品也成為生產(chǎn)蒸汽的熱源。這些包括泥煤、木材及木材廢棄物、麥稈、咖啡渣、玉米稈、煤礦廢棄物（煤屑）、煉鋼爐廢熱甚至太陽能。

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.現(xiàn)代美國(guó)中心電站以煤作為主要燃料，使用煙煤、次煙煤或褐煤。雖然天然氣和燃油也許是未來化石燃料電廠的燃料選擇，但對(duì)于帶基本負(fù)荷的新電站，煤仍將是主要的鍋爐燃料。

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頁）

2.3.1 煤的分類

由于煤是一種不均勻的物質(zhì)，且其組成和特性變動(dòng)很大，所以建立煤的分類系統(tǒng)是很必要的。中國(guó)煤的性質(zhì)如表2-1所示。以煤階進(jìn)行煤的分類是典型的做法。這表現(xiàn)為煤化程度的大小：從褐煤到貧煤、煙煤以及無煙煤。煤階表明了煤的地質(zhì)歷史和主要特性。

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.現(xiàn)在美國(guó)應(yīng)用的煤分類標(biāo)準(zhǔn)是由美國(guó)材料試驗(yàn)學(xué)會(huì)（ASTM）建立的。其分類是通過煤的工業(yè)分析所確定的揮發(fā)分和固定碳的含量以及煤的發(fā)熱量作為分類標(biāo)準(zhǔn)。這套系統(tǒng)目的在于確定煤的商業(yè)使用價(jià)值，并提供關(guān)于煤燃燒特性的基本信息。

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 燃燒系統(tǒng)

鍋爐內(nèi)化石燃料燃燒以產(chǎn)生蒸汽的技術(shù)已成熟多年。然而，在過去的二十多年中，為了將大氣排放和污染降到可行的最低程度，燃燒技術(shù)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

教材27頁

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.油燃燒系統(tǒng)

所有的電站鍋爐都燃用油，在燃煤鍋爐中點(diǎn)燃煤粉，在煤進(jìn)入爐膛之前加熱爐膛并升壓，而在燃油鍋爐中則作為主要負(fù)荷燃料。一般地，燃油都是粘度在3500 sec到6500sec的殘?jiān)剂嫌汀榱擞行У娜紵@些油必須被加熱到120~130℃并被良好地分散或霧化成很小的微滴。

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，要比一般的餾分油（柴油，汽油等）便宜，但又帶來一些問題：酸性污染物和粉塵的排放。酸性污染問題是由石油中的硫產(chǎn)生的，硫分的含量有時(shí)可高達(dá)3%。在20世紀(jì)60年代早期，人們對(duì)油燃燒器設(shè)計(jì)進(jìn)行了深入研究和開發(fā)，目的在于解決燃油的排放問題。由此誕生了一種油燃燒器——“標(biāo)準(zhǔn)燃燒器”，它可以在非常低的過量空氣系數(shù)下減少碳排放。為保證鍋爐中每個(gè)燃燒器獲得同樣多的空氣也做了大量的工作。目前油燃燒過量空氣系數(shù)運(yùn)行水平為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.煤燃燒系統(tǒng) 煤燃燒器的發(fā)展模式同油燃燒器類似，而且重點(diǎn)放在準(zhǔn)確控制每只燃燒器煤和油的供給量。實(shí)際中所有的燃煤鍋爐都是燃燒煤粉（由磨煤機(jī)生產(chǎn)），這些煤粉經(jīng)過很好的粉碎，然后由空氣流（一次風(fēng)）送入燃燒器。同以前相比，在流動(dòng)平衡上的設(shè)計(jì)成果現(xiàn)在已能使鍋爐在較低的過量空氣水平下運(yùn)行，并在不增加飛灰含碳量水平的情況下提高了總的效率。

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, 這樣，結(jié)合低NOx燃燒器的開發(fā)，就使氣體排放達(dá)到歐共體的標(biāo)準(zhǔn)，這也是兩代鍋爐轉(zhuǎn)換（已完成）的主要目的，即設(shè)定500MW燃煤鍋爐可能達(dá)到的NOx排放水平。在第三代鍋爐的設(shè)計(jì)中進(jìn)行了進(jìn)一步降低NOx的開拓性試驗(yàn)。

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.煤燃燒系統(tǒng)部件的布置必須根據(jù)經(jīng)濟(jì)因素和煤的性質(zhì)來確定。作為整個(gè)燃燒系統(tǒng)設(shè)計(jì)的性能參數(shù)，煤粉細(xì)度、磨煤機(jī)出口溫度、空煤比等都必須達(dá)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燃燒系統(tǒng)

影響NOx生成的因素包括燃料含氮量、火焰峰值溫度、火焰中的可用氧量以及氣流在鍋爐系統(tǒng)中的停留時(shí)間。當(dāng)煤進(jìn)入爐膛其化學(xué)結(jié)構(gòu)被破壞時(shí)，一些煤中的化合氮就作為揮發(fā)分被釋放出來。由大氣中的氮生成的一氧化氮即“熱力型NOx”可以通過減少煙氣在高溫區(qū)域的停留時(shí)間而得到控制，這樣就會(huì)控制燃燒階段中可用氧量，最后生成的是無害氮而不是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?yàn)槊涸谌紵齾^(qū)的燃燒需要一定的過量氧氣以便使所有的碳燃盡，且不含氮的煤是難以獲得的，因此NOx的減少必須依靠鍋爐和燃燒器的設(shè)計(jì)來完成。

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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.天然氣燃燒系統(tǒng)

天然氣曾經(jīng)作為電廠主要燃料。然而一些年來，沒有太多的天然氣可供電廠使用，并且人們沒有正視這樣的事實(shí)，即天然氣作為一種優(yōu)質(zhì)燃料將會(huì)重新得到大量應(yīng)用。

丙烷常常作為一種點(diǎn)火劑，廣泛地應(yīng)用于燃油鍋爐和燃煤鍋爐中的油燃燒器。

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 流化床燃燒

流化床燃燒是煤粉燃燒方式的一種，采用這種燃燒方式時(shí)煤在空氣中的燃燒發(fā)生在流化床中，典型的是循環(huán)流化床。循環(huán)流化床最適合于燃燒低成本廢棄燃料、低品質(zhì)或低熱量煤。將煤粒和石灰石投入到床中，石灰石在床內(nèi)煅燒成石灰。流化床中主要是石灰和少量的煤，煤焦在其中循環(huán)。運(yùn)行中的床溫很低，只有427℃(800℉)，在這個(gè)溫度下的熱力學(xué)環(huán)境有利于減少NOx的形成和捕集SO2，使之與CaO 反應(yīng)生成CaSO4。對(duì)于煤燃燒，蒸汽循環(huán)可以是亞臨界，也可能是超臨界，它們具有相近的發(fā)電效率。循環(huán)流化床技術(shù)的最大的優(yōu)點(diǎn)是它在床中捕捉SO2的能力和它對(duì)煤質(zhì)的廣泛適應(yīng)性，其中包括低熱量煤、高灰分煤和低揮發(fā)分煤，并且在運(yùn)行中可以改變煤種。循環(huán)流化床鍋爐適合與生物質(zhì)共燃，最近就新建了幾臺(tái)燃燒褐煤的循環(huán)流化床機(jī)組。

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

圖2-1 循環(huán)流化床鍋爐設(shè)計(jì)布置實(shí)例 教材29頁

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.如圖2-1所示，目前最常用的流化床技術(shù)是循環(huán)流化床燃燒技術(shù)。煤和煤焦燃燒的同時(shí)，空氣攜帶煤、煤焦、煤灰和脫硫劑通過爐膛。固體材料通過旋風(fēng)分離器從煙氣中分離出來，然后通過對(duì)流煙道部分，煙氣把熱量傳給爐管以產(chǎn)生高壓蒸汽。另一部分蒸汽是由流化床中的高溫固體在返回爐膛前放出熱量產(chǎn)生的。爐膛內(nèi)固體快速運(yùn)動(dòng)會(huì)引起過量的磨損，因此爐膛底部不安裝爐管。通過低燃燒

29-12 溫度和空氣分級(jí)燃燒來控制NOx的生成。SOx排放通過床中石灰脫硫劑控制。這些為煙氣凈化節(jié)省了大筆的投資，但是低的SOx排放需要燃燒低硫分煤，并且NOx的排放受燃燒反應(yīng)的限制。極低的排放需要額外的煙氣凈化設(shè)備，同時(shí)會(huì)增加相應(yīng)的維護(hù)成本。在中國(guó)最大的流化床鍋爐是330MWe，設(shè)計(jì)最大的鍋爐是600 MWe，但是還沒有投建。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 制粉系統(tǒng)

煤粉制備與煤粉燃燒技術(shù)的發(fā)展是同步的。為了使煤在爐膛中有效燃燒，煤在離開燃燒器時(shí)必須被粉碎到一定的大小，這樣才能迅速燃燒，這就意味著煤必須被加工成小顆粒，才能被迅速加熱到著火溫度并和空氣良好混合。磨煤機(jī)的工作就是把煤磨碎到符合上述要求的合適的大小。較早的系統(tǒng)使用筒式球磨機(jī)磨煤粉，并且在燃燒前利用儲(chǔ)倉(cāng)暫時(shí)儲(chǔ)存煤粉。如果對(duì)該技術(shù)進(jìn)行改進(jìn)，去掉中間儲(chǔ)倉(cāng)而將從磨煤機(jī)出來的煤粉直接送去燃燒，就會(huì)對(duì)磨煤機(jī)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.正壓制粉系統(tǒng)中，提供煤粉輸送介質(zhì)的一次風(fēng)機(jī)位于磨煤機(jī)前，因而它運(yùn)送的是清潔空氣，不會(huì)像排粉風(fēng)機(jī)一樣受到侵蝕磨損。這是正壓磨煤系統(tǒng)的主要優(yōu)點(diǎn)。然而，磨煤機(jī)需要由單獨(dú)風(fēng)機(jī)提供高于磨煤機(jī)內(nèi)部壓力的密封空氣。

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.正壓磨煤機(jī)的一個(gè)缺點(diǎn)是它必須完全由空氣密封以避免煤粉泄露到大氣中。相對(duì)來說，負(fù)壓磨煤機(jī)的密封標(biāo)準(zhǔn)并不需要這樣高，但也不允許漏入過多空氣，因?yàn)槔淇諝怆y以干燥濕煤。這種方式泄露的空氣量也無法測(cè)量，如果達(dá)到高的空/煤比，遇到明火則可能發(fā)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

磨輥在一層耐磨層上滾動(dòng)，通過移動(dòng)的磨盤把煤壓碎。磨輥的運(yùn)動(dòng)引起煤粒間的相互運(yùn)動(dòng)同時(shí)磨輥的壓力在煤粒間形成壓力負(fù)荷。一定壓力下在煤粒層上的運(yùn)動(dòng)引起摩擦（煤粒依靠摩擦力破碎），這就是磨煤機(jī)的工作原理。耐磨層具有緩沖作用，雖然降低了磨的效率，但也大大降低了磨輥的磨損。當(dāng)磨煤區(qū)的工作面間距離很近時(shí)，比如到了一個(gè)顆粒大小，三個(gè)部件（磨輥，顆粒，磨盤）間的磨損就會(huì)大大增加，磨損速率會(huì)是正常磨煤機(jī)的100倍。當(dāng)帶有石英的石頭尺寸等于或大于磨層厚度時(shí)，也會(huì)在運(yùn)行中發(fā)生三部件接觸的磨損。

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.隨著磨煤的進(jìn)行，為了防止過度磨制和降低能耗及磨損，磨好的煤粉從磨煤機(jī)中排出。圖2-2是MPS型中速磨的示意圖，顯示了中速磨煤機(jī)的基本組成。在磨煤機(jī)下部有一個(gè)轉(zhuǎn)動(dòng)的臺(tái)面，稱為輥胎的輥?zhàn)釉谂_(tái)面上滾動(dòng)。原煤由上部的磨煤機(jī)給入，然后在磨輥和轉(zhuǎn)動(dòng)的磨盤間經(jīng)過，磨輥下的煤就被磨碎了。離心力加上磨輥對(duì)煤層的沉降力共同作用，將部分磨好的煤粉擠出磨盤邊緣，由上升的空氣流流化并攜帶這些煤粉。

圖2-2 磨煤機(jī)內(nèi)部的顆粒循環(huán)

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.空氣進(jìn)入點(diǎn)一般稱為進(jìn)風(fēng)環(huán)，噴嘴環(huán)或者喉部。上升的空氣流與煤粒混合在進(jìn)風(fēng)環(huán)上面產(chǎn)生流化的顆粒床。空氣的流速很低，以至于只能攜帶少部分的煤粒通過床層過濾。空氣和煤粒離開流化床形成了第一步的分離。預(yù)熱的空氣同時(shí)干燥煤粉以保證煤粉的有效燃燒。

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裝置。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，但是需要的一次風(fēng)溫度則要求使用特殊材料，并且增加了磨煤機(jī)著火的可能。實(shí)際運(yùn)行的水分最大值是40%（質(zhì)量），此時(shí)要求一次風(fēng)溫高達(dá)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頁 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.空氣煤粉向上流動(dòng)時(shí)，由于流動(dòng)面積增大使流動(dòng)速度降低，大粒徑的煤粒就會(huì)回落到磨盤上。最后的煤粉分離采用磨煤機(jī)上部的粗粉分離器，粗粉分離器是利用離心力的分離裝置。風(fēng)粉混合物以一定角度進(jìn)入，從而發(fā)生旋轉(zhuǎn)并產(chǎn)生離心力。粗一點(diǎn)的煤粉沖擊到分離器的周29-15 邊，不再保持懸浮狀態(tài)而回落到磨盤上。風(fēng)粉混合物中的細(xì)煤粉顆粒保持懸浮狀態(tài)，并最終上升進(jìn)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.圖2-3 典型的鋼球磨制粉系統(tǒng)

2.4.2低速磨

筒式鋼球磨是現(xiàn)在仍在使用的最早的磨煤機(jī)。它是一個(gè)臥式的筒體，里面裝有小直徑的鋼球。筒體內(nèi)襯耐磨材料以加強(qiáng)球的滾動(dòng)，球占筒體總?cè)莘e的25%到30%。轉(zhuǎn)速取離心力可以克服重力時(shí)速度的80%，這樣可以使鋼球貼在筒體的內(nèi)壁上。通過筒體轉(zhuǎn)動(dòng)時(shí)鋼球的碰撞來實(shí)現(xiàn)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.筒式鋼球磨有單進(jìn)單出和雙進(jìn)雙出兩種。對(duì)于單進(jìn)單出型，空氣和煤從一端進(jìn)入從另一端流出。雙進(jìn)雙出型磨煤機(jī)是空氣和原煤從兩端進(jìn)入，磨好的干燥的煤粉從兩端流出。對(duì)于這兩種類型，粗粉分離器布置于磨煤機(jī)的外部，粒徑過大的粗粉被送回到磨煤機(jī)與原煤混合。筒式鋼球磨不具有類似立式磨的流化床特點(diǎn)，同時(shí)由于空氣和煤粉的混合不均勻限制了干燥能力。如果筒式鋼球磨要磨的煤中水分高于20%，就必須使用輔助的干燥裝置，比如破碎干燥機(jī)。

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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對(duì)新建鍋爐來說，中速磨已經(jīng)大量的取代了筒式鋼球磨。相對(duì)于中速磨，筒式鋼球磨往往需要大的建筑空間和較高的能耗。同時(shí)，筒式鋼球磨難于控制且有較高的磨損速度。但是，筒式鋼球磨能很好的適應(yīng)極具磨損作用的、低水分的難磨燃料，比如石油焦。煤在其中較長(zhǎng)的停留時(shí)間可以實(shí)現(xiàn)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制粉系統(tǒng)

磨煤機(jī)只是龐大的制粉系統(tǒng)的一部分，制粉系統(tǒng)一般有直吹式和中儲(chǔ)式兩種。在直吹式系統(tǒng)中，從磨煤機(jī)出來的煤粉直接參與燃燒過程，同時(shí)參與的還有空氣、水蒸汽和通入磨煤機(jī)的熱能。中儲(chǔ)式系統(tǒng)把煤粉從空氣、水蒸汽和通入磨煤機(jī)的能量中分離開再去燃燒。儲(chǔ)倉(cāng)中的煤粉由新的一次風(fēng)輸送到燃燒設(shè)備。目前生產(chǎn)蒸汽的過程中很少采用中儲(chǔ)式制粉系統(tǒng)，但是很多特殊的場(chǎng)合仍然需要，比如煤氣化和高爐投煤。目前在美國(guó)運(yùn)行的中速磨大約有1000臺(tái)，其中99%以上的是直吹式系統(tǒng)。

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.直吹式系統(tǒng)的主要部件有：

(1)給煤機(jī)，通過煤倉(cāng)調(diào)節(jié)進(jìn)入磨煤機(jī)的給煤量。(2)熱源，用來預(yù)熱干燥煤粉的一次風(fēng)

29-17(3)一次風(fēng)機(jī)，典型的情況是作為鼓風(fēng)機(jī)布置于磨煤機(jī)之前（正壓系統(tǒng)），或作為排粉風(fēng)機(jī)位于磨煤機(jī)之后（負(fù)壓系統(tǒng)）

(4)磨煤機(jī)，作為正壓系統(tǒng)或負(fù)壓系統(tǒng)的主體部分。(5)管路，把煤和一次風(fēng)從磨煤機(jī)輸送到燃燒器(6)燃燒器，混合煤粉和平衡燃燒空氣(7)控制和調(diào)節(jié)裝置

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.根據(jù)工程的經(jīng)濟(jì)性，以上部件可以按照不同的形式布置。在正壓系統(tǒng)中，需要做出選擇，是采用熱一次風(fēng)風(fēng)機(jī)（每個(gè)磨一個(gè)風(fēng)機(jī)），還是采用冷風(fēng)風(fēng)機(jī)（布置在特定的空氣加熱器前面）。熱風(fēng)輸送系統(tǒng)初始投資費(fèi)用較低，因?yàn)椴恍枰囟ǖ目諝饧訜崞鳌?duì)大型機(jī)組而言，冷風(fēng)風(fēng)機(jī)系統(tǒng)具有較低的運(yùn)行費(fèi)用，可以補(bǔ)償較高的初始投資。

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.中速磨這個(gè)術(shù)語是指空氣引入到磨煤機(jī)中作為一次風(fēng)用來干燥和輸送煤粉。一次風(fēng)的控制對(duì)制粉系統(tǒng)的正常運(yùn)行是非常重要的。不管是直吹式還是中儲(chǔ)式制粉系統(tǒng)，也不管采用熱風(fēng)還是冷風(fēng)風(fēng)機(jī)系統(tǒng)都需要普遍的控制。必須控制一次風(fēng)量和磨煤機(jī)出口溫度，這個(gè)控制由三個(gè)相互聯(lián)系的節(jié)氣閥來實(shí)現(xiàn)。

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.其中的兩個(gè)是熱和冷的節(jié)氣閥，用來調(diào)節(jié)磨煤機(jī)的空氣溫度，這些節(jié)氣閥通常是相互關(guān)聯(lián)的，從而保證一個(gè)開啟另一個(gè)則關(guān)閉。第三個(gè)節(jié)氣閥是獨(dú)立的，用來控制空氣容積。一些生產(chǎn)商只采用兩個(gè)節(jié)氣閥，但是缺乏穩(wěn)定性，而變負(fù)荷時(shí)的低反應(yīng)能力抵消了初投資的減少帶來的好處。

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

圖2-4 燃煤鍋爐（機(jī)組）

2.5 系統(tǒng)布置和主要部件

現(xiàn)代鍋爐具有復(fù)雜的熱力—水力（蒸汽和水）受熱面結(jié)構(gòu)，以預(yù)熱和蒸發(fā)水，產(chǎn)生過熱蒸汽。這些受熱面是這樣布置的：（1）燃料在最小污染排放的情況下完全有效地燃燒；（2）按要求產(chǎn)生一定流量、壓力和溫度的蒸汽；（3）最大限度地回收能量。一個(gè)相對(duì)簡(jiǎn)單的燃煤電站鍋爐如圖2－4所示。產(chǎn)生蒸汽和熱量回收系統(tǒng)中的主要部件有：（1）爐膛和對(duì)流煙道（2）蒸汽過熱器（第一級(jí)和第二級(jí)）（3）蒸汽再熱器（4）產(chǎn)生蒸汽的管組（僅僅存在于工業(yè)鍋爐中）（5）省煤器（6）汽包（或鍋筒）（7）減溫器和蒸汽溫度控制系統(tǒng)（8）空氣預(yù)熱器

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爐膛

爐膛是一個(gè)四周封閉的開口大空間，燃料在其中燃燒，產(chǎn)生的煙氣在進(jìn)入對(duì)流煙道前得到冷卻。離開爐膛進(jìn)入管束的煙氣溫度過高則會(huì)導(dǎo)致煙塵微粒沉積在管壁上或使金屬管壁超溫。燃料和燃燒設(shè)備的類型對(duì)爐膛的幾何形狀和尺寸影響很大。在這種情況下，磨細(xì)的煤粉被送入爐膛懸浮燃燒。燃燒產(chǎn)物上升穿過爐膛上部。過熱器、再熱器和省煤器等受熱面被特定布置于鍋爐圍墻內(nèi)部的水平或垂直煙道內(nèi)（對(duì)流煙道）。

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.在現(xiàn)代蒸汽發(fā)生器中，爐膛和對(duì)流煙道的爐墻是由碳鋼或低合金鋼的汽冷或水冷壁組成，以維持爐墻的金屬溫度在允許的范圍內(nèi)。這些管子在頂部和底部由聯(lián)箱或母管連接在一起。這些聯(lián)箱用來分配或收集水、蒸汽或汽水混合物。在最現(xiàn)代化的機(jī)組中，爐墻管道也作為主要的產(chǎn)生蒸汽的部件或受熱面。這些管子用鋼條焊接在一起，組成氣密的、連續(xù)的、剛性的膜式墻。這些管道通常預(yù)制成可裝運(yùn)的膜板，并且板上留有燃燒器口、觀察孔、吹灰器口（鍋爐清潔設(shè)備）和燃?xì)鈬娙肟凇?/p>

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 過熱器和再熱器

過熱器和再熱器被專門設(shè)計(jì)成順列管束，用來提高飽和蒸汽的溫度。一般形式下，它們

29-20 是簡(jiǎn)單的單相換熱器，蒸汽在管道內(nèi)流動(dòng)，煙氣從外面經(jīng)過，通常二者是交叉流動(dòng)。由于其較高的運(yùn)行溫度，這些關(guān)鍵的部件一般用合金鋼制造。典型的布置通常有利于控制出口蒸汽的溫度，保持金屬溫度低于其可接受的極限和控制蒸汽流動(dòng)的壓力損失。

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.過熱器和再熱器的主要區(qū)別是蒸汽壓力。在典型的汽包鍋爐中，過熱器的出口壓力為2700psi（186bar），而再熱器的出口壓力為580psi（40bar）。受熱面的結(jié)構(gòu)設(shè)計(jì)和布置取決于所要求的出口溫度、吸熱量、燃料的灰分特性和清潔設(shè)備。這些受熱面可以呈水平或垂直布置。過熱器和有的再熱器經(jīng)常被分為幾段以利于控制蒸汽溫度和優(yōu)化熱量回收。

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.過熱器的類型 根據(jù)煙氣側(cè)的傳熱方式，過熱器可分為兩種基本類型。最初的一種是對(duì)流過熱器，從煙氣吸收的輻射熱量很小。在這樣的機(jī)組中，蒸汽溫度隨鍋爐負(fù)荷的增加而升高，這是因?yàn)闋t膛吸收單位輸入熱量的百分比下降。這導(dǎo)致過熱器吸收了更多的熱量。因?yàn)閷?duì)流傳熱速率幾乎與煙氣流率即鍋爐負(fù)荷成直線關(guān)系，因此，過熱器中每磅蒸汽的總吸熱量以及蒸汽的溫度都會(huì)隨鍋爐負(fù)荷而增長(zhǎng)（見圖2－5）。過熱器布置得離爐膛越遠(yuǎn)，進(jìn)入過熱器的煙氣溫度越低，這種效果越明顯。

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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圖2-5 布置有對(duì)流和輻射過熱器的在一定負(fù)荷范圍內(nèi)出口汽溫基本均勻 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.輻射式過熱器主要吸收來自爐膛的輻射熱，對(duì)流傳熱量很少。一般采用較大間距（24英寸或很大的側(cè)邊距）的屏式凝渣管或懸吊屏式過熱器的型式布置于爐膛中。有時(shí)這種過熱器和包墻管組合成一體。因?yàn)闋t膛受熱面吸熱不如鍋爐負(fù)荷增長(zhǎng)快，所以隨著鍋爐負(fù)荷的增長(zhǎng)輻射式過熱汽溫度反而下降，如圖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.某些情況下，在較大的負(fù)荷范圍內(nèi)，這兩條變化趨勢(shì)相反的曲線可由一系列聯(lián)合的輻射、對(duì)流過熱器疊加為平緩的過熱曲線，如圖2-4所示。一個(gè)單獨(dú)加熱的過熱器也能產(chǎn)生平緩的過熱曲線。

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.輻射和對(duì)流式過熱器的設(shè)計(jì)需要特別注意避免因蒸汽和煙氣流量分配不均而造成的管子超溫。一般過熱器中有100,000到1,000,000lb/hft(136到1356kg/ms)或更多的蒸汽質(zhì)量流量。這種設(shè)置是在允許壓降的范圍內(nèi)對(duì)管子內(nèi)部進(jìn)行充分的冷卻。質(zhì)量流量的選擇取決于蒸汽的壓力和溫度，還有過熱器的熱負(fù)荷。此外，高速下的高壓損會(huì)改善蒸汽側(cè)流場(chǎng)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 省煤器和空氣預(yù)熱器

省煤器和空氣預(yù)熱器在提高鍋爐總的熱效率方面發(fā)揮著重要作用, 它們回收了排入大氣前煙氣中的低品位熱量，也就是低溫?zé)崃俊煔獗皇∶浩骰蚩諝忸A(yù)熱器冷卻每40℉（22℃），總的鍋爐效率就會(huì)被提高大約1%。省煤器吸熱加熱鍋爐給水，空氣預(yù)熱器則是加熱燃燒空氣。熱空氣強(qiáng)化了多種燃料的燃燒，并保證了穩(wěn)定的著火。

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 省煤器是一種逆流布置的熱交換器，在流過過熱器或再熱器（如果使用）的煙氣中獲取能量。它提高了汽包進(jìn)水的溫度。其管束布置是一種典型的平行水平蛇形管束，水在管內(nèi)流動(dòng)而煙氣在外側(cè)反方向（逆流）流動(dòng)。管子間盡量緊密以強(qiáng)化傳熱，同時(shí)要求有足夠的管子表面清潔空間和合理的煙氣側(cè)壓損。根據(jù)設(shè)計(jì)，這些管子內(nèi)一般不會(huì)產(chǎn)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、最可靠的省煤器設(shè)計(jì)就是光管、順列、交叉流省煤器（如圖2-6）。煤燃燒后，飛灰就會(huì)產(chǎn)生一種高污垢、侵蝕的環(huán)境。相對(duì)于如圖2-6的錯(cuò)列布置，這些順列布置的光管就會(huì)盡可能減少飛灰粘附、侵蝕的可能性。這也是通過吹灰器保持清潔的最簡(jiǎn)單的幾何形狀。然而，這種布置的好處必須要結(jié)合它大重量、大空間以及造價(jià)進(jìn)行綜合評(píng)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.為減少投資，大多數(shù)鍋爐省煤器應(yīng)用了各種鰭片以強(qiáng)化煙氣側(cè)的傳熱效率。鰭片是廉價(jià)的非承壓物件，它可減少省煤器的總尺寸和造價(jià)。然而，成功的應(yīng)用對(duì)于煙氣環(huán)境是非常敏感的。表面的清潔能力是一關(guān)鍵因素。

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.空氣預(yù)熱器 空氣預(yù)熱器是利用經(jīng)過省煤器的鍋爐煙氣攜帶的熱量加熱燃燒空氣，并提供干燥煤粉的熱空氣。在燃煤電廠中，空氣預(yù)熱器的出口溫度受限于磨煤機(jī)的出口溫度和調(diào)溫風(fēng)系統(tǒng)容量，煙氣出口溫度則要考慮傳熱表面的污染和后面設(shè)備的腐蝕情況。

On older boiler tubular or plate recuperators [間壁式換熱器]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 [回轉(zhuǎn)式] are used.在較老的鍋爐中一般采用管式或板式空預(yù)器，體積大，很難清理，而且壞損的傳熱表面不易替換。現(xiàn)代鍋爐都采用回轉(zhuǎn)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.回轉(zhuǎn)式空氣預(yù)熱器的最大特點(diǎn)是顯著地節(jié)省了空間。回轉(zhuǎn)式空預(yù)器采用緊密的受熱面布置方式，必須采用性能良好的吹灰器使其保持清潔。

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.受熱面由壓制成特殊形狀的鋼板或考登鋼板組成。這些板子厚0.5到0.8mm，一般被壓緊并裝進(jìn)置于支撐結(jié)構(gòu)上的鋼制倉(cāng)體。這些板子的形狀經(jīng)過優(yōu)化，具有很高的傳熱效率，同時(shí)要在使用吹灰器充分保持清潔的情況下保證壓損最小。

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頁

geometries and the effect of replacement element type which may be required because of fouling problems.一臺(tái)660MW的單元機(jī)組配有兩臺(tái)空氣預(yù)熱器，每臺(tái)直徑14.6m，重約500噸。傳熱元件的表面積總共約100,000平方米。燃煤電廠典型的溫度應(yīng)是煙氣進(jìn)口335℃，出口120℃，空氣進(jìn)口32℃，出口290℃。空氣預(yù)熱器的性能主要表現(xiàn)在傳熱效率、壓損以及空氣對(duì)煙氣側(cè)的泄漏上。前兩項(xiàng)能被理想的表示為一組無量綱數(shù)：雷諾數(shù)、普朗特?cái)?shù)和斯坦頓數(shù)的關(guān)系。通過實(shí)驗(yàn)室規(guī)模試驗(yàn)可以確立每種空氣預(yù)熱器組件的關(guān)系式。這就可以進(jìn)行優(yōu)化設(shè)計(jì)，估算新開發(fā)部件的幾何性能，以及評(píng)估由于灰污問題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 鍋爐在線吹灰

是否高效的燃燒化石燃料來生產(chǎn)電力很大程度上取決于蒸汽產(chǎn)生設(shè)備對(duì)煤燃燒產(chǎn)物（煤灰）的適應(yīng)性。吹灰器用來吹掃沉積在鍋爐受熱面上的積灰來保證有效地向蒸汽傳熱。在英國(guó)吹灰介質(zhì)大部分用蒸汽而在美國(guó)一般用空氣。

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)應(yīng)用蒸汽或空氣的爐膛吹灰器

按照要求，短伸縮式吹灰器在吹掃爐膛壁面時(shí)向前旋轉(zhuǎn)推進(jìn)，同時(shí)打開空氣或蒸汽。其總的行程大約200-250mm。根據(jù)設(shè)計(jì)要求，吹灰槍可以在120°范圍內(nèi)擺動(dòng)或者在限位開關(guān)下做整圈的運(yùn)動(dòng)，直到吹灰槍縮回。這種吹灰器的吹掃半徑為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.爐膛的吹掃介質(zhì)也可以用水，但實(shí)際中很少應(yīng)用。水通常用來在低速下清除爐膛內(nèi)頑固的熔融的渣。用變速馬達(dá)來保證噴水在受熱面上有相同的停留時(shí)間。

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)長(zhǎng)伸縮式吹灰器

長(zhǎng)伸縮式吹灰器用來吹掃過熱器、再熱器有時(shí)還有省煤器。當(dāng)吹灰器啟動(dòng)時(shí)，吹灰槍向前移動(dòng)，同時(shí)旋轉(zhuǎn)來保證對(duì)沖的射流形成螺旋狀的運(yùn)動(dòng)。當(dāng)利用噴口吹掃爐墻時(shí)，就打開吹灰介質(zhì)使其流向噴口。

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.當(dāng)吹灰槍行程達(dá)到最大時(shí)，吹灰槍旋轉(zhuǎn)90度角，這樣在返回時(shí)與進(jìn)入的吹灰部分錯(cuò)開。沒有支撐的吹灰槍長(zhǎng)度可達(dá)16.75m，因此鍋爐爐寬可以設(shè)計(jì)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)聲波吹灰器

聲波吹灰器在電站鍋爐不同位置進(jìn)行了試驗(yàn)。這個(gè)裝置是個(gè)壓縮空氣驅(qū)動(dòng)的低頻(20Hz)發(fā)聲器，產(chǎn)生共振頻率波，可以吹掃4900m3的空間。試驗(yàn)結(jié)果是個(gè)綜合效果，因此預(yù)言聲波吹灰器的應(yīng)用范圍還為時(shí)過早。

Until recently, steam was used exclusively for soot blowing.Air was first used in the USA.目前為止，一直采用蒸汽吹灰，空氣吹灰的首次應(yīng)用是在美國(guó)。

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頁

? 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.空氣吹灰有以下優(yōu)點(diǎn)：

? ? ? ? ? ? ? 在任何負(fù)荷下都可以得到有效的吹灰。

由于沒有凝結(jié)水、熱沖擊和對(duì)吹灰槍、噴嘴等部件的磨蝕，吹灰器的維護(hù)費(fèi)用大大降低。

對(duì)空氣管件不需要預(yù)熱，并且相對(duì)于蒸汽吹灰，凝結(jié)水的排放大大減小。管件不需要保溫。

由于爐管磨蝕造成的故障和停爐減少了50%或更多。空氣吹灰可以使空氣預(yù)熱器的受熱面壽命增加一倍。

相對(duì)于包括蒸汽減壓站的蒸汽吹灰系統(tǒng)，空氣壓縮機(jī)和吹灰器及系統(tǒng)的維護(hù)費(fèi)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.拋開以上優(yōu)點(diǎn)，空氣吹灰也有其他的一些附加初始費(fèi)用，如空壓機(jī)、馬達(dá)、開關(guān)設(shè)備、電纜和壓縮機(jī)房。但是，從500MW鍋爐的運(yùn)行數(shù)據(jù)上來看，兩種吹灰系統(tǒng)的能耗相當(dāng)。

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

由熱力學(xué)第一定律，蒸汽發(fā)生器系統(tǒng)的能量平衡如下所述： 進(jìn)入系統(tǒng)的能量-離開系統(tǒng)的能量 = 系統(tǒng)內(nèi)部能量的積累

因?yàn)檎羝l(fā)生器應(yīng)在穩(wěn)態(tài)下檢測(cè)，這樣積累的能量就為0，其方程為： 進(jìn)入系統(tǒng)的能量 = 離開系統(tǒng)的能量 進(jìn)入系統(tǒng)的能量就是進(jìn)入系統(tǒng)的質(zhì)量流所攜帶的能量，以及輔助設(shè)備的驅(qū)動(dòng)能量。離開系統(tǒng)的能量就是離開系統(tǒng)的質(zhì)量流所攜帶的能量，以及通過蒸汽發(fā)生器表面?zhèn)鬟f給環(huán)境的能量。

Efficiency is the ratio of energy output to energy input, expressed as a percentage:

EF?100Output,%(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.效率為輸出能量和輸入能量的比值，以百分?jǐn)?shù)的形式表示：

EF?100Output,%(2-1)

Input 當(dāng)輸入能量定義為燃料釋放的所有能量時(shí)，所得的效率通常稱為燃料效率。

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，采用能量損失和外來熱量來計(jì)算效率。能量平衡法是確定效率的首選方法。因?yàn)闇y(cè)量誤差僅影響著各項(xiàng)損失而不影響總能量，所以它一般情況下比輸入－輸出法更精確。例如：如總損失占總輸入能量的10%，則1%的測(cè)量誤差僅會(huì)導(dǎo)致0.1%的效率誤差，而在測(cè)量燃料流量中1%的誤差將會(huì)導(dǎo)致效率的1%的誤差。能量平衡法的另一個(gè)優(yōu)點(diǎn)就是可以確認(rèn)兩次效率測(cè)試結(jié)果不同的原因，另外，對(duì)于諸如燃料分析數(shù)據(jù)等試驗(yàn)條件的變化，該方法可以容易的將效率修正到基準(zhǔn)工況或保證工況。

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頁（第2章結(jié)束）

2.7.2 效率-輸入-輸出法（正平衡法）

根據(jù)輸入-輸出法計(jì)算的效率是基于測(cè)定燃料量和計(jì)算輸出能量所必需的鍋爐汽水側(cè)參數(shù)。該方法計(jì)算的效率的不確定度直接與燃料測(cè)量、樣本燃料分析和鍋爐輸出能量求取等的不確定度成正比。所以，要獲得可靠的結(jié)果，在精確測(cè)量上述各項(xiàng)時(shí)必須格外謹(jǐn)慎。

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第二篇：熱能與動(dòng)力工程專業(yè)英語翻譯Ch 01 教案

1.3 傳熱學(xué)基礎(chǔ)

傳熱學(xué)是一門研究在存在溫差的物體間發(fā)生能量傳遞的科學(xué)。熱力學(xué)中將這種方式傳遞的能量定義為熱量。傳熱學(xué)不僅可以解釋熱量傳遞是如何傳遞的，而且可以計(jì)算在特定條件下的傳熱速率。事實(shí)上，傳熱速率正是一個(gè)分析所期望的目標(biāo)，它指明了傳熱學(xué)和熱力學(xué)間的差別。熱力學(xué)處理的是平衡狀態(tài)下的系統(tǒng)，它可計(jì)算當(dāng)系統(tǒng)從一個(gè)平衡狀態(tài)過渡到另一個(gè)平衡狀態(tài)時(shí)所需要的能量，但不能解決系統(tǒng)處于過渡過程的非平衡狀態(tài)時(shí)能量變化的快慢程度。傳熱學(xué)提供了可用于計(jì)算傳熱速率的實(shí)驗(yàn)關(guān)聯(lián)式，從而對(duì)熱力學(xué)第一定律和第二定律進(jìn)行補(bǔ)充。這里，我們介紹熱量傳遞的三種方式和不同型式的換熱器。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

q???A?T

(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 熱傳導(dǎo)

當(dāng)物體內(nèi)部存在溫度梯度時(shí)，經(jīng)驗(yàn)表明，就有能量從高溫區(qū)向低溫區(qū)傳遞。我們說，此時(shí)的能量通過傳導(dǎo)進(jìn)行傳遞，單位面積上的傳熱速率與法向溫度梯度成正比，即q/A~?T/?x。引入比例系數(shù)，則有

q???A?T

(1-3)?x其中q是熱流量，?T/?x是熱流方向上的溫度梯度，正常數(shù)?稱為材料的導(dǎo)熱系數(shù)。方程中插入的負(fù)號(hào)表示熱傳導(dǎo)過程應(yīng)滿足熱力學(xué)第二定律，即熱量必須沿溫度降低的方向傳遞。式(1-3)稱為傅立葉導(dǎo)熱定律，以法國(guó)數(shù)理學(xué)家約瑟夫?傅立葉的名字命名，傅立葉在導(dǎo)熱的分析處理方面做出了極其重大的貢獻(xiàn)。值得注意的是，式(1-3)也是導(dǎo)熱系數(shù)的定義式，在典型的單位體系中，當(dāng)熱流量q的單位為W時(shí)，?的單位為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.圖1-8 對(duì)流換熱

1.3.2 對(duì)流換熱

眾所周知，與熱金屬板放置在靜止的空氣中相比，放置在轉(zhuǎn)動(dòng)的風(fēng)扇前的熱金屬板會(huì)更快地冷卻。我們說熱量通過對(duì)流進(jìn)行傳遞，稱此類換熱過程為對(duì)流換熱。對(duì)流這個(gè)術(shù)語給讀者提供了有關(guān)傳熱過程的直觀概念，然而，必須擴(kuò)展這種直觀概念，使我們可以達(dá)到對(duì)某一問題進(jìn)行充分的分析和處理。例如，我們知道流過熱平板的空氣速度會(huì)明顯影響其傳熱量，但它是以線性方式影響冷卻的嗎？即如果速度增加一倍，傳熱量也會(huì)增加一倍嗎？我們猜想，如果用水代替空氣冷卻熱平板，傳熱量可能有所不同，但是，二者的差異會(huì)有多少呢？這些問題在了解一些非常基本的分析后，可得以回答。現(xiàn)在，我們來簡(jiǎn)要描述對(duì)流換熱的物理機(jī)理，并且說明它和傳導(dǎo)過程的聯(lián)系。

圖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

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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.被加熱的平板如圖1-8所示，平板的溫度為Tw，流體的溫度為T∞。速度分布如圖所示，受黏性作用，平板上的速度減小為零。因?yàn)楸诿嫣幜鲃?dòng)薄層的速度為零，因此，在該點(diǎn)上熱量只能以導(dǎo)熱方式傳遞。因此，可以利用式(1-3)，以及壁面上的流體導(dǎo)熱系數(shù)和溫度梯度來計(jì)算傳熱量。如果熱量在該層經(jīng)導(dǎo)熱傳遞，那么，為什么我們要談及對(duì)流換熱以及需要考慮流體速度的影響呢？答案是，溫度梯度依賴于流體帶走熱量的速度，較高的流速將產(chǎn)生較大的溫度梯度。因此，壁面上的溫度梯度依賴于流場(chǎng)的變化，在以后的分析中，我們將建立這二者間的關(guān)系。然而，必須記住，壁面上傳熱的物理機(jī)理是一導(dǎo)熱過程。

To express the overall effect of convection.We use Newton’s law of cooling:

q?hA(Tw?T?)

(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.為描述對(duì)流換熱的整體效應(yīng)，應(yīng)用牛頓冷卻定律

q?hA(Tw?T?)

(1-4)這里，熱流量與壁面和流體間的整體溫度差以及表面積A有關(guān)。參數(shù)h稱為對(duì)流換熱系數(shù)，式(1-4)是其定義式。對(duì)某些傳熱過程，可獲得h的分析表達(dá)式，而復(fù)雜情形下的傳熱系數(shù)必須通過實(shí)驗(yàn)研究來確定。式(1-4)表明，當(dāng)熱流量的單位為W時(shí)，h的單位為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.如果將熱平板置于沒有外部風(fēng)源的房間空氣中，平板附近的密度梯度將造成空氣運(yùn)動(dòng)。我們稱此換熱過程為自然對(duì)流，以區(qū)別于風(fēng)扇吹掃平板表面時(shí)形成的強(qiáng)制對(duì)流。沸騰和凝結(jié)現(xiàn)象也屬于對(duì)流換熱的范疇。

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 輻射換熱

對(duì)于導(dǎo)熱和對(duì)流換熱，其熱量傳遞需要介質(zhì)才得以進(jìn)行，與此不同的是，熱量也可以在完全真空中傳遞，其傳熱機(jī)理是電磁輻射。我們將討論限定在由溫差導(dǎo)致的電磁輻射，即所謂的熱輻射。

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

qemitted??AT

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.熱力學(xué)研究表明，對(duì)于理想的熱輻射體或黑體，其輻射力正比于物體絕對(duì)溫度的四次方及其表面積，因此有

qemitted??AT4

(1-5)式中，?為比例系數(shù)，稱為斯忒藩－玻耳茲曼常數(shù)，其值為5.669×10-8 W/(m2·K4)。式(1-5)稱為熱輻射的斯忒藩－玻耳茲曼定律，該式僅適用于黑體。值得注意的是，該表達(dá)式僅適用于熱輻射，其它類型的電磁輻射要比該式復(fù)雜得多。

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頁

式(1-5)只能用于確定單個(gè)黑體的輻射能。兩個(gè)表面間的凈輻射換熱量與其絕對(duì)溫度四次方的差成正比，即

qnet　exchangeA??(T14?T24)

(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

q?F?FG?A(T14?T24)

(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).我們已經(jīng)提到，黑體是按四次方定律輻射能量的物體。因其黑色的表面我們稱之為黑體，如覆蓋炭黑的金屬片，就近似具有這種輻射特性。其它類型的表面，如有光澤的漆面或拋光的金屬板，并不具有黑體那樣大的輻射力，然而，這些物體的輻射力仍大致與T14成正比。為了考慮這些表面的“灰”特性，在式(1-5)引入另一個(gè)參數(shù)，稱為發(fā)射率ε，發(fā)射率將這些“灰”表面的輻射與理想黑體的表面輻射聯(lián)系起來。此外，我們必須考慮這樣一個(gè)事實(shí)，并非一個(gè)表面發(fā)出的所有輻射都可以到達(dá)到另一個(gè)表面，因?yàn)殡姶泡椛涫茄刂本€傳播的，將有部分能量散失到周圍環(huán)境中。因此，考慮到這兩種情況，式(1-5)引入另外兩個(gè)新的參數(shù)，則有

44q?FF?A(T?T)

(1-7)?G1

2式中，F(xiàn)ε是發(fā)射率函數(shù)，F(xiàn)G是幾何角系數(shù)。此時(shí)，值得提醒讀者的是，式(1-7)中的這兩個(gè)函數(shù)通常并不是相互獨(dú)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 [環(huán)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 換熱器的類型

最簡(jiǎn)單的換熱器是由兩個(gè)不同直徑的同心圓管組成，稱為套管式換熱器。套管換熱器中的一種流體流經(jīng)細(xì)管，另一種流體流經(jīng)兩管間的環(huán)形區(qū)域。套管換熱器中包括兩種不同類型的流動(dòng)方式：一種為順流，即冷、熱流體從同一端進(jìn)入換熱器，并沿同一方向流動(dòng)；另一種為逆流，即冷、熱流體從相反的兩端進(jìn)入換熱器，且沿相反方向流動(dòng)。

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.另一類換熱器，被專門設(shè)計(jì)成單位體積內(nèi)有很大的換熱面積，稱為緊湊式換熱器。換熱器的換熱面積與其體積之比稱為面積密度β。β＞700 m2/m3的換熱器歸為緊湊式換熱器。例如汽車散熱器（β≈1000 m2/m3）、燃?xì)廨啓C(jī)中的玻璃陶瓷換熱器（β≈6000 m2/m3）、斯特林機(jī)的回?zé)崞鳎é隆?5,000 m2/m3）以及人的肺部（β≈20,000 m2/m3）。緊湊式換熱器能實(shí)現(xiàn)小容積內(nèi)兩種流體的高換熱率，通常用于換熱器重量和容積受到嚴(yán)格限制的場(chǎng)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.圖1-9 緊湊式換熱器通過在分離兩種流體的壁面上附加間隔緊密的薄板或波紋翅片來擴(kuò)展其表面。緊湊式換熱器通常用于氣－氣和氣－液（或液－氣）換熱器，通過增加傳熱面積來抵消氣側(cè)低傳熱系數(shù)所帶來的影響。例如，汽車散熱器是水－氣緊湊式換熱器的典型例子，通常管子氣側(cè)表面裝有翅片。

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.圖1-9 管-殼式換熱器簡(jiǎn)圖

工業(yè)應(yīng)用中最常見的換熱器也許是管殼式換熱器，如圖1-9所示。管殼式換熱器外殼里封裝有大量的管束（有時(shí)為數(shù)百根），其軸線與外殼軸線平行。當(dāng)一種流體在管內(nèi)流動(dòng)，另一種流體在管外流動(dòng)并穿過殼體時(shí)，就進(jìn)行了熱交換。殼內(nèi)通常布置有擋板，用于使殼側(cè)流體沿殼流動(dòng)以強(qiáng)化傳熱，并保持均勻的管間距。雖然管殼式換熱器應(yīng)用廣泛，但因其相對(duì)較大的尺寸和重量，因而并不適用于汽車和航空器領(lǐng)域。注意，管殼式換熱器的管束兩側(cè)開口處的較大流動(dòng)區(qū)域稱為封頭，它位于殼體兩端，管側(cè)流體流入、流出管子前后都在此匯集。

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.管殼式換熱器依據(jù)所含管程和殼程的數(shù)目可進(jìn)一步分類。例如，換熱器殼內(nèi)的所有管束采用一個(gè)U型布置的稱為單殼程雙管程換熱器（1-2型換熱器）。同樣地，含有雙殼程和四管程的換熱器叫做雙殼程－四管程型換熱器（2-4型換熱器）。

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.一種廣泛使用的新型換熱器是板翅式（或板式）換熱器，它由一系列平板組成，并形成波紋狀的流動(dòng)通道。冷、熱流體在間隔的每個(gè)通道中流動(dòng)，每一股冷流體被兩股熱流體所包圍，因此換熱效果非常好。此外，板式換熱器可通過簡(jiǎn)單添加更多的平板來滿足增強(qiáng)換熱的需求。該類型換熱器非常適用于液－液式換熱場(chǎng)合，但需要冷、熱液流的壓強(qiáng)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頁 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.另一類冷、熱流體交替通過同一流動(dòng)面積的換熱器為蓄熱式換熱器。靜態(tài)型蓄熱式換熱器基本上由多孔介質(zhì)組成，其熱容量大，如陶瓷鐵絲網(wǎng)。冷、熱流體交替地流經(jīng)這些多孔介質(zhì)，熱量先由流過的高溫流體傳遞到換熱器的換熱基體，再由基體傳遞給接著流過的低溫流體。因此，基體充當(dāng)了臨時(shí)儲(chǔ)熱介質(zhì)的作用。動(dòng)態(tài)型蓄熱式換熱器內(nèi)有轉(zhuǎn)筒，冷、熱流體連續(xù)流動(dòng)通過轉(zhuǎn)筒的不同部分，使得轉(zhuǎn)筒的任一部分周期性地通過熱流體，存儲(chǔ)熱量，再通過冷流體，釋放存儲(chǔ)的熱量。轉(zhuǎn)筒作為熱量從熱流體傳遞到冷流體的媒介。

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頁

換熱器往往被賦予特定的名稱來反映它們的特定用途。例如，冷凝器是流體流經(jīng)它時(shí)會(huì)發(fā)生冷卻凝結(jié)的一種換熱器。鍋爐是另一類換熱器，流體在其內(nèi)吸熱并汽化。空間輻射器是以輻射方式將熱流體的熱量傳遞到周圍空間的換熱器。

第三篇：熱能與動(dòng)力工程專業(yè)介紹

熱能與動(dòng)力工程專業(yè)介紹

（工學(xué)、能源動(dòng)力類、專業(yè)代碼：080501）

一、專業(yè)簡(jiǎn)介

（一）培養(yǎng)目標(biāo)

本專業(yè)以能源工業(yè)為特色，培養(yǎng)德智體美全面發(fā)展，具有較扎實(shí)的理論基礎(chǔ)和專業(yè)技術(shù)知識(shí)，較好的綜合素質(zhì)與較強(qiáng)的工程技術(shù)應(yīng)用能力，受到工程師的基本訓(xùn)練。

熱力發(fā)電廠方向，主要從事熱能與動(dòng)力工程設(shè)備和系統(tǒng)的設(shè)計(jì)、運(yùn)行、管理、技術(shù)研究與開發(fā)，節(jié)能等方面的應(yīng)用型高級(jí)技術(shù)人才。

風(fēng)能與動(dòng)力工程方向，主要從事現(xiàn)代風(fēng)力發(fā)電場(chǎng)的運(yùn)行、管理、規(guī)劃、設(shè)計(jì)與施工、風(fēng)能資源測(cè)量與評(píng)估等方面的應(yīng)用型高級(jí)技術(shù)人才。

（二）專業(yè)內(nèi)容

熱力發(fā)電廠方向，是將常規(guī)能源（化石燃料、天然氣、石油）在鍋爐內(nèi)燃燒產(chǎn)生的化學(xué)能轉(zhuǎn)化成熱能，通過工質(zhì)推動(dòng)熱動(dòng)力設(shè)備做功，將熱能轉(zhuǎn)化為機(jī)械能，帶動(dòng)發(fā)電機(jī)將機(jī)械能轉(zhuǎn)化為電能。

風(fēng)能與動(dòng)力工程方向，是將空氣的動(dòng)能通過風(fēng)力機(jī)轉(zhuǎn)化成機(jī)械能，帶動(dòng)風(fēng)力發(fā)電機(jī)將機(jī)械能轉(zhuǎn)化為電能。

（三）專業(yè)特色

本專業(yè)以能源工業(yè)為特色，認(rèn)真貫徹黨的教育方針，堅(jiān)持專業(yè)建設(shè)以社會(huì)需求為導(dǎo)向的辦學(xué)思想，凸顯能源資源特色，以應(yīng)用型人才培養(yǎng)為目標(biāo)，構(gòu)建知識(shí)、能力與創(chuàng)新的課程體系，為寧夏及周邊區(qū)域能源資源建設(shè)提供所需的應(yīng)用型人力資源。

二、主干課程

熱力發(fā)電廠方向：工程熱物理、熱能動(dòng)力

主要課程：流體力學(xué)、工程熱力學(xué)、傳熱學(xué)、電工電子技術(shù)、電廠鍋爐、汽輪機(jī)原理、熱力發(fā)電廠、換熱器設(shè)計(jì)、理論力學(xué)、材料力學(xué)、熱工自動(dòng)化儀表、泵與風(fēng)機(jī)、機(jī)械設(shè)計(jì)基礎(chǔ)等。

風(fēng)能與動(dòng)力工程方向：風(fēng)能動(dòng)力

主要課程：流體力學(xué)、空氣動(dòng)力學(xué)、電工電子技術(shù)，理論力學(xué)、材料力學(xué)、自動(dòng)控制理論，風(fēng)力機(jī)原理，風(fēng)電機(jī)組設(shè)計(jì)制造，風(fēng)電場(chǎng)電氣工程、風(fēng)資源測(cè)量與評(píng)估、電機(jī)學(xué)、風(fēng)力發(fā)電場(chǎng)、機(jī)械設(shè)計(jì)基礎(chǔ)等。

三、就業(yè)方向

畢業(yè)生可在大型能源企業(yè)和相關(guān)公司，如熱力發(fā)電廠、風(fēng)力發(fā)電場(chǎng)、汽輪機(jī)廠、鍋爐制造廠、風(fēng)力機(jī)設(shè)備制造廠等，從事系統(tǒng)的設(shè)計(jì)、運(yùn)行、管理、技術(shù)研究與開發(fā)，新能源利用等方面的工作。

第四篇：熱能與動(dòng)力工程專業(yè)求職信

熱能與動(dòng)力工程專業(yè)求職信1

尊敬的公司領(lǐng)導(dǎo)：

您好！

非常感謝您在百忙之中翻閱我的自薦表。

畢業(yè)在即，貴公司良好的聲譽(yù)和工作環(huán)境深深吸引了我，我由衷地希望能夠成為你們的一員，共創(chuàng)輝煌。

在校期間，我始終把自身素質(zhì)的培養(yǎng)放在第一位，努力學(xué)習(xí)掌握科學(xué)文化知識(shí)和專業(yè)技能，學(xué)習(xí)成績(jī)和綜合積分居專業(yè)上游。以良好的成績(jī)，一次性的'通過了所有課程。在外語方面，通過了日語國(guó)家四級(jí)和日語國(guó)際二級(jí)，自修了大眾英語，已達(dá)初級(jí)水平。在計(jì)算機(jī)應(yīng)用方面，熟練掌握了cad制圖、office辦公軟件等，另對(duì)internet有一定的了解和認(rèn)識(shí)。另外，由于個(gè)人興趣，自學(xué)了管理、營(yíng)銷、金融等方面的知識(shí)。

學(xué)習(xí)之余，為鍛煉自己多方面的能力，積極參加了各種社會(huì)實(shí)踐活動(dòng)，每個(gè)假期都積極參加了社會(huì)實(shí)踐，對(duì)我國(guó)社會(huì)狀況和工業(yè)狀況有了初步的了解，下廠實(shí)習(xí)的時(shí)間多觀察，勤思考加強(qiáng)了理論同實(shí)際的結(jié)合，為適應(yīng)時(shí)代要求，參加了機(jī)動(dòng)車駕駛班，并拿到了機(jī)動(dòng)車駕駛c照，此外，還參加了很多的公益活動(dòng)。曾無償獻(xiàn)血一次，在九冬會(huì)期間，報(bào)名參加志愿者為九冬會(huì)獻(xiàn)了一份微薄之力。

尊敬的公司領(lǐng)導(dǎo)，如果您選擇了我，我會(huì)一步一個(gè)腳印，真真實(shí)實(shí)地走好每一步，用實(shí)際行動(dòng)來證明您的選擇是英明的。

衷心希望貴公司給我一個(gè)發(fā)展的機(jī)會(huì)！

祝愿貴公司事業(yè)蒸蒸日上！

熱能與動(dòng)力工程專業(yè)求職信2

尊敬的領(lǐng)導(dǎo)：

您好!

我是吉林大學(xué)汽車工程學(xué)院熱能與動(dòng)力工程專業(yè)97屆的一名學(xué)生，即將面臨畢業(yè)。

吉林大學(xué)南嶺校區(qū)是我國(guó)著名的汽車、機(jī)械等人才的重點(diǎn)培養(yǎng)基地，具有悠久的歷史和優(yōu)良的傳統(tǒng)，并且素以治學(xué)嚴(yán)謹(jǐn)、育人有方而著稱;吉林大學(xué)南嶺校區(qū)汽車學(xué)院則被譽(yù)為我國(guó)汽車工業(yè)的搖籃。在這樣的學(xué)習(xí)環(huán)境下，無論是在知識(shí)能力，還是在個(gè)人素質(zhì)修養(yǎng)方面，我都受益匪淺。

四年來，在師友的嚴(yán)格教益及個(gè)人的努力下，我具備了扎實(shí)的專業(yè)基礎(chǔ)知識(shí)，系統(tǒng)地掌握了熱能與動(dòng)力工程專業(yè)的有關(guān)理論;熟悉涉外工作常用禮儀;具備較好的英語聽、說、讀、寫、譯等能力;能熟練操作計(jì)算機(jī)辦公軟件。同時(shí)，我利用課余時(shí)間廣泛地涉獵了大量書籍，不但充實(shí)了自己，也培養(yǎng)了自己多方面的技能。更重要的是，嚴(yán)謹(jǐn)?shù)膶W(xué)風(fēng)和端正的學(xué)習(xí)態(tài)度塑造了我樸實(shí)、穩(wěn)重、創(chuàng)新的性格特點(diǎn)。

此外，我還積極地參加各種社會(huì)活動(dòng)，抓住每一個(gè)機(jī)會(huì)，鍛煉自己。大學(xué)四年，我深深地感受到，與優(yōu)秀學(xué)生共事，使我在競(jìng)爭(zhēng)中獲益;向?qū)嶋H困難挑戰(zhàn)，讓我在挫折中成長(zhǎng)。前輩們教我勤奮、盡責(zé)、善良、正直;吉林大學(xué)培養(yǎng)了我實(shí)事求是、開拓進(jìn)取的作風(fēng)。我熱愛貴單位所從事的事業(yè)，殷切地期望能夠在您的領(lǐng)導(dǎo)下，為這一光榮的事業(yè)添磚加瓦;并且在實(shí)踐中不斷學(xué)習(xí)、進(jìn)步。

收筆之際，鄭重地提一個(gè)小小的要求：無論您是否選擇我，尊敬的領(lǐng)導(dǎo)，希望您能夠接受我誠(chéng)懇的謝意!祝愿貴單位事業(yè)蒸蒸日上!

此致

敬禮!

求職者：

第五篇：熱能與動(dòng)力工程專業(yè)之我見

熱能與動(dòng)力工程專業(yè)之我見

一 專業(yè)概述

本專業(yè)培養(yǎng)具備熱能工程、傳熱學(xué)、流體力學(xué)、動(dòng)力機(jī)械、動(dòng)力工程等方面基礎(chǔ)知識(shí)，能在國(guó)民經(jīng)濟(jì)和部門，從事動(dòng)力機(jī)械(如熱力發(fā)動(dòng)機(jī)、流體機(jī)械、水力機(jī)械)的動(dòng)力工程(如熱電廠工程、水電動(dòng)力工程、制冷及低溫工程、空調(diào)工程)的設(shè)計(jì)、制造、運(yùn)行、管理、實(shí)驗(yàn)研究和安裝、開發(fā)、營(yíng)銷等方面的高級(jí)工程技術(shù)人才。

熱能與動(dòng)力工程專業(yè)可分成以下三個(gè)專業(yè)方向：

1.以熱能轉(zhuǎn)換與利用系統(tǒng)為主的熱能動(dòng)力工程（能源利用）；

2.以內(nèi)燃機(jī)及其驅(qū)動(dòng)系統(tǒng)為主的熱力發(fā)動(dòng)機(jī)及汽車工程方向（發(fā)動(dòng)機(jī)）；

3.以電能、熱能轉(zhuǎn)換為機(jī)械功為主的流體機(jī)械與制冷低溫工程方向（制冷、空調(diào)）；

培養(yǎng)要求

本專業(yè)主要學(xué)習(xí)動(dòng)力工程及工程熱物理的基礎(chǔ)理論，學(xué)習(xí)各種能量轉(zhuǎn)換及有效利用的理論和技術(shù)，受到現(xiàn)代動(dòng)力工程師的基本訓(xùn)練；具有進(jìn)行動(dòng)力機(jī)械與熱工設(shè)備設(shè)計(jì)、運(yùn)行、實(shí)驗(yàn)研究的基本能力。

畢業(yè)生應(yīng)獲得以下幾方面的知識(shí)和能力：

1.具有較扎實(shí)的自然科學(xué)基礎(chǔ)，較好的人文、藝術(shù)和社會(huì)科學(xué)基礎(chǔ)及正確運(yùn)用本國(guó)語言、文字的表達(dá)能力；

2.較系統(tǒng)地掌握本專業(yè)領(lǐng)域?qū)拸V的技術(shù)理論基礎(chǔ)知識(shí)，主要包括工程力學(xué)、機(jī)械學(xué)、工程熱物理、流體力學(xué)、電工與電子學(xué)、控制理論、市場(chǎng)經(jīng)濟(jì)及企業(yè)管理等基礎(chǔ)知識(shí)；

3.獲得本專業(yè)領(lǐng)域的工程實(shí)踐訓(xùn)練，具有較強(qiáng)的計(jì)算機(jī)和外語應(yīng)用能力；

4.具有本專業(yè)領(lǐng)域內(nèi)某個(gè)專業(yè)方向所必要的專業(yè)知識(shí)，了解其科學(xué)前沿及發(fā)展趨勢(shì)；

5.具有較強(qiáng)的自學(xué)能力、創(chuàng)新意識(shí)和較高的綜合素質(zhì)。

培養(yǎng)目標(biāo)

本專業(yè)主要培養(yǎng)能源轉(zhuǎn)換與利用和熱力環(huán)境保護(hù)領(lǐng)域具有扎實(shí)的理論基礎(chǔ)，較強(qiáng)的實(shí)踐、適應(yīng)和創(chuàng)新能力，較高的道德素質(zhì)和文化素質(zhì)的高級(jí)人才，以滿足社會(huì)對(duì)該能源動(dòng)力學(xué)科領(lǐng)域的科研、設(shè)計(jì)、教學(xué)、工程技術(shù)、經(jīng)營(yíng)管理等各方面的人才需求。學(xué)生應(yīng)具備寬廣的自然科學(xué)、人文和社會(huì)科學(xué)知識(shí)，熱學(xué)、力學(xué)、電學(xué)、機(jī)械、自動(dòng)控制、系統(tǒng)工程等寬厚理論基礎(chǔ)、熱能動(dòng)力工程專業(yè)知識(shí)和實(shí)踐能力，掌握計(jì)算機(jī)應(yīng)用與自動(dòng)控制技術(shù)方面的知識(shí)。畢業(yè)生能從事能源與動(dòng)力工程及相關(guān)方面的研究、教學(xué)、開發(fā)、制造、安裝、檢修、策劃、管理和營(yíng)銷等工作。

我校提出卓越工程師計(jì)劃，旨在培養(yǎng)理論基礎(chǔ)扎實(shí)，有較強(qiáng)的研究能力，技術(shù)過硬，有很強(qiáng)的動(dòng)手能力的復(fù)合型人才。

主干學(xué)科

動(dòng)力工程與工程熱物理、機(jī)械工程

主要課程

工程力學(xué)、機(jī)械設(shè)計(jì)基礎(chǔ)、電工與電子技術(shù)、工程熱力學(xué)、流體力學(xué)、傳熱

學(xué)、控制理論、測(cè)試技術(shù)等主要實(shí)踐性教學(xué)環(huán)節(jié)：包括軍訓(xùn)、金工、電工、電子實(shí)習(xí)、認(rèn)識(shí)實(shí)習(xí)、生產(chǎn)實(shí)習(xí)、社會(huì)實(shí)踐、課程設(shè)計(jì)、畢業(yè)設(shè)計(jì)(論文)等，一般應(yīng)安排40周以上。

主要專業(yè)實(shí)驗(yàn)

傳熱學(xué)實(shí)驗(yàn)、工程熱力學(xué)實(shí)驗(yàn)、動(dòng)力工程測(cè)試技術(shù)實(shí)驗(yàn)等

知識(shí)結(jié)構(gòu)要求

工具性知識(shí)：比較系統(tǒng)地掌握一門外語，掌握外文科技寫作知識(shí)。掌握計(jì)算機(jī)軟、硬件技術(shù)的基本知識(shí)，具有在本專業(yè)與相關(guān)領(lǐng)域的計(jì)算機(jī)應(yīng)用與開發(fā)能力；掌握通過網(wǎng)絡(luò)獲取信息的知識(shí)、方法與工具。能夠進(jìn)行中外文文獻(xiàn)檢索。

自然科學(xué)知識(shí)：掌握高等數(shù)學(xué)、大學(xué)物理、工程化學(xué)、生命科學(xué)、環(huán)境科學(xué)等方面的知識(shí)。

學(xué)科技術(shù)基礎(chǔ)知識(shí)：掌握工程制圖、工程數(shù)學(xué)、理論力學(xué)、材料力學(xué)、機(jī)械原理、機(jī)械設(shè)計(jì)基礎(chǔ)、金屬工藝學(xué)、電工學(xué)、CAE有限元設(shè)計(jì)、液壓傳動(dòng)、電子技術(shù)基礎(chǔ)、工程流體力學(xué)、工程熱力學(xué)、傳熱學(xué)、計(jì)算機(jī)原理與應(yīng)用、自動(dòng)控制原理等方面的知識(shí)(對(duì)水利水電動(dòng)力工程方向，工程熱力學(xué)、傳熱學(xué)知識(shí)要求可適當(dāng)降低)。

專業(yè)知識(shí)：根據(jù)本專業(yè)人才培養(yǎng)目標(biāo)和培養(yǎng)規(guī)格，因?qū)I(yè)方向的不同而有所差別。

（1）熱能轉(zhuǎn)換系統(tǒng)工程(能源利用)主要掌握熱能與動(dòng)力測(cè)試技術(shù)、鍋爐原理、汽輪機(jī)原理、能源概論、燃燒污染與環(huán)境、動(dòng)力機(jī)械設(shè)計(jì)、熱力發(fā)電廠、熱工自動(dòng)控制、傳熱傳質(zhì)數(shù)值計(jì)算、流體機(jī)械、內(nèi)燃機(jī)設(shè)計(jì)等知識(shí)。

（2）熱力發(fā)動(dòng)機(jī)及汽車工程方向（發(fā)動(dòng)機(jī)）掌握內(nèi)燃機(jī)（或透平機(jī)）原理、結(jié)構(gòu)，設(shè)計(jì)，測(cè)試，燃料和燃燒，熱力發(fā)動(dòng)機(jī)排放與環(huán)境工程，能源工程概論，內(nèi)燃機(jī)電子控制，熱力發(fā)動(dòng)機(jī)傳熱和熱負(fù)荷，汽車工程概論、汽車?yán)碚摗⑵囍圃旃に噷W(xué)等方面的知識(shí)。

（3）制冷低溫工程與流體機(jī)械方向（制冷空調(diào)）掌握制冷、低溫原理、人工環(huán)境自動(dòng)化、暖通空調(diào)系統(tǒng)、低溫技術(shù)學(xué)、熱工過程自動(dòng)化、流體機(jī)械原理、流體機(jī)械系統(tǒng)仿真與控制等方面的知識(shí)。使學(xué)生掌握該方向所涉及的制冷空調(diào)系統(tǒng)、低溫系統(tǒng)，制冷空調(diào)與低溫各種設(shè)備和裝置，各種軸流式、離心式壓縮機(jī)和各種容積式壓縮機(jī)的基本理論和知識(shí)。

也就是說，本專業(yè)學(xué)生應(yīng)具有如下知識(shí)和能力，并根據(jù)培養(yǎng)規(guī)格的不同而有所側(cè)重：

（1）具有較扎實(shí)的自然科學(xué)基礎(chǔ)，熟練掌握高等數(shù)學(xué)、工程數(shù)學(xué)、大學(xué)物理、工程化學(xué)等基礎(chǔ)性課程的基本理論和應(yīng)用方法；具有較好的人文、藝術(shù)和社會(huì)科學(xué)基礎(chǔ)及正確應(yīng)用本國(guó)語言、文字的表達(dá)能力。

（2）掌握一門外國(guó)語，具有較好的聽、說、讀、寫能力，能較順利地閱讀本專業(yè)的外文書籍和資料。若外語為英語應(yīng)達(dá)到國(guó)家四級(jí)以上水平（含四級(jí)）。

（3）系統(tǒng)地掌握本專業(yè)必需的技術(shù)基礎(chǔ)理論，主要包括力學(xué)理論（理論力學(xué)、材料力學(xué)、流體力學(xué)），熱學(xué)理論（熱力學(xué)、傳熱學(xué)等），機(jī)械設(shè)計(jì)基本理論，電工與電子基本理論，自動(dòng)控制理論，能源動(dòng)力工程基礎(chǔ)理論等。

（4）熟悉本專業(yè)領(lǐng)域內(nèi)1～2個(gè)專業(yè)方向或有關(guān)方面的專業(yè)知識(shí)，了解其學(xué)

科前沿和發(fā)展趨勢(shì)。

（5）具有本專業(yè)必需的制圖、計(jì)算、測(cè)試、調(diào)研、查閱文獻(xiàn)和基本工藝、操作、運(yùn)行等基本技能。

（6）具有一定計(jì)算機(jī)相關(guān)知識(shí)和較強(qiáng)的計(jì)算機(jī)應(yīng)用能力，較熟練使用計(jì)算機(jī)工具，解決工程中的有關(guān)問題。

（7）具有較強(qiáng)的自學(xué)能力、分析能力和創(chuàng)新意識(shí)。

二 個(gè)人學(xué)習(xí)方向

本人傾向能源利用和發(fā)動(dòng)機(jī)這兩個(gè)方向

全球資源緊張，環(huán)境持續(xù)惡化，為了保證人們?cè)絹碓礁叩奈镔|(zhì)享受，我們必須提高能源的利用率，同時(shí)尋找新的替代能源——節(jié)源、開流——節(jié)源是開流的緩沖階段，為開流爭(zhēng)取時(shí)間。所以個(gè)人傾向能源利用這一方向。

發(fā)動(dòng)機(jī)可為能源利用的研究提供資料，是兩個(gè)相輔相成的專業(yè)方向。

三 學(xué)習(xí)計(jì)劃

擬在大一完成上述工具性知識(shí)的學(xué)習(xí)以及初步了解專業(yè)理論知識(shí)和發(fā)展動(dòng)向 擬在大二完成專業(yè)理論知識(shí)的學(xué)習(xí)，熟練專業(yè)方向所需的技能，具有初步理論論證、設(shè)計(jì)能力

擬在大三深入專業(yè)理論知識(shí)，同時(shí)具備較強(qiáng)的動(dòng)手操作能力

擬在大四具備獨(dú)立的研究能力及熟練的專業(yè)實(shí)踐能力，有較強(qiáng)的社會(huì)生存能力