锅炉专业英语

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 Circulating fluidized bed CFB 循环流化床锅炉 Coal char 煤焦

Cogenerator 热电联产机组 Combustion 燃烧 Equalization 均衡，平衡 Erosive 侵蚀的，腐蚀的

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

Drum 汽包

Dwell time 保留时间 Economizer 省煤器 Embrittlement 脆性，脆化 Ingress进口，入口 In-line 顺列

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 Potassium 钾

Prandtl numbers 普朗特数 Prefabricated 预制的 Premium fuel 优质燃料

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 Slurry 水煤浆 Sodium 钠 Solvents 溶剂 Sootblower 吹灰器

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

Vulnerable 易损的，薄弱的 Wear磨损 Welded 焊接 Wingwall屏式凝渣管 Yttrim 釔

Abbreviations

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 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

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

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。

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 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

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 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 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 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 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 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.

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

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 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 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。

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（相对的有受压件pressure parts），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 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 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。在欧洲大陆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 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 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.

? 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(air compressors)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 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:

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.

效率为输出能量和输入能量的比值，以百分数的形式表示：

EF?100Output,% (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 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

教材39页

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.

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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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