有关锅炉英文文献

Controlling the Furnace Process in Coal-Fired BoilersThe unstable trends that exist in the market of fuel supplied to thermal power plants and the situations in which the parameters of their operation need to be changed (or preserved), as well as the tendency toward the economical and environmental requirements placed on them becoming more stringent, are factors that make the problem of controlling the combustion and heat transfer processes in furnace devices very urgent. The solution to this problem has two aspects. The first involves development of a combustion technology and,accordingly, the design of a furnace device when new installations are designed. The second involves modernization of already existing equipment. In both cases,the technical solutions being adopted must be properly substantiated with the use of both experimental and calculation studies.The experience Central Boiler-Turbine Institute Research and Production Association (Ts KTI) and Zi O specialists gained from operation of boilers and experimental investigations they carried out on models allowed them to propose several new designs of multicell and maneuverable—in other words, controllable—furnace devices that had been put in operation at power stations for several years. Along with this, an approximate zero-one-dimensional, zone wise calculation model of the furnace process in boilers had been developed at the Tsk Ti, which allowed Tsk Ti specialists to carry out engineering calculations of the main parameters of this process and calculate studies of furnaces employing different technologies of firing and combustion modes .Naturally, furnace process adjustment methods like changing the air excess factor, stack gas recirculation fraction, and distribution of fuel and air among the tiers of burners, as well as other operations written in the boiler operational chart, are used during boiler operation.However, the effect they have on the process is limited in nature. On the other hand, control of the furnace process in a boiler implies the possibility of making substantial changes in the conditions under which the combustion and heat transfer proceed in order to considerably expand the range ofloads, minimize heat losses, reduce the extent to which the furnace is contaminated with slag, decrease the emissions of harmful substances, and shift to another fuel. Such a control can be obtained by making use of the following three main factors:(i) the flows of oxidizer and gases being set to move in the flame in a desired aerodynamic manner;(ii) the method used to supply fuel into the furnace and the place at which it is admitted thereto;(iii) the fineness to which the fuel is milled.The latter case implies that a flame-bed method is used along with the flame method for combusting fuel.The bed combustion method can be implemented in three design versions: mechanical grates with a dense bed, fluidized-bed furnaces, and spouted-bed furnaces.As will be shown below, the first factor can be made to work by setting up bulky vorticisms transferring large volumes of air and combustion products across and along the furnace device. If fuel is fired in a flame, the optimal method of feeding it to the furnace is to admit it to the zones near the centers of circulating vorticisms, a situation especially typical of highly intense furnace devices. The combustion process in these zones features a low air excess factor (α< 1) and a long local time for which the components dwell in them, factors that help make the combustion process more stable and reduce the emission of nitrogen oxides .Also important for the control of a furnace process when solid fuel is fired is the fineness to which it is milled; if we wish to minimize incomplete combustion, the degree to which fuel is milled should be harmonized with the location at which the fuel is admitted into the furnace and the method for supplying it there, for the occurrence of unburned carbon may be due not only to incomplete combustion of large-size fuel fractions, but also due to fine ones failing to ignite (especially when the content of volatiles Daff < 20%).Owing to the possibility of pictorially demonstrating the motion of flows, furnace aerodynamics is attracting a great deal of attention of researchers and designers who develop and improve furnace devices. At the same time, furnace aerodynamics lies at the heart of mixing (mass transfer), a process the quantitativeparameters of which can be estimated only indirectly or by special measurements. The quality with which components are mixed in the furnace chamber proper depends on the number, layout, and momenta of the jets flowing out from individual burners or nozzles, as well as on their interaction with the flow of flue gases, with one another, or with the wall.It was suggested that the gas-jet throw distance be used as a parameter determining the degree to which fuel is mixed with air in the gas burner channel. Such an approach to estimating how efficient the mixing is may to a certain degree be used in analyzing the furnace as a mixing apparatus. Obviously, the greater the jet length (and its momentum), the longer the time during which the velocity gradient it creates in the furnace will persist there, a parameter that determines how completely the flows are mixed in it. Note that the higher the degree to which a jet is turbulence at the outlet from a nozzle or burner, the shorter the distance which it covers, and, accordingly, the less completely the components are mixed in the furnace volume. Once through burners have advantages over swirl ones in this respect.It is was proposed that the extent to which once through jets are mixed as they penetrate with velocity w2 and density ρ2 into a transverse (drift) flow moving with velocity w1 and having density ρ1 be correlated with the relative jet throw distance in the following wayWhere ks is a proportionality factor that depends on the “pitch” between the jet axes (ks= 1.5–1.8).The results of an experimental investigation in which the mixing of gas with air in a burner and then in a furnace was studied using the incompleteness of mixing as a parameter are reported in 5.A round once through jet is intensively mixed with the surrounding medium in a furnace within its initial section, where the flow velocity at the jet axis is still equal to the velocity w2 at the nozzle orifice of radius r0.The velocity of the jet blown into the furnace drops very rapidly beyond the confines of the initial section, and the axis it has in the case of wall-mounted burners bends toward the outlet from the furnace.One may consider that there are three theoretical models for analyzing the mixing of jets with flow rate G2 that enter into a stream with flow rate G1. The firstmodel is for the case when jets flow into a “free” space (G1= 0),the second model is for the case when jets flow into a transverse (drift) current with flow rate G1 G2，and the third model is for the case when jets flow into a drift stream with flow rateG1<G2. The second model represents mixing in the channel of a gas burner, and the third model represents mixing in a furnace chamber. We assume that the mixing pattern we have in a furnace is closer to the first model than it is to the second one, since 0 <G1/G2< 1, and we will assume that the throw distance h of the jet being drifted is equal to the length S0 of the “free” jet’s initial section. The ejection ability of the jet being drifted then remains the same as that of the “free” jet, and the length of the initial section can be determined using the well-known empirical formula of G.N. Amphibrachic [6] ：S0= 0.67r0/a, (2)where a is the jet structure factor and r0 is the nozzle radius.At a = 0.07, the length of the round jet’s initial section is equal to 10 r0 and the radius the jet has at the transition section (at the end of the initial section) is equal to 3.3 r0. The mass flow rate in the jet is doubled in this case. The corresponding minimum furnace cross-sectional area Ff for a round once through burner with the outlet cross-sectional area Fb will then be equal to and t he ratio Ff/Fb≈20. This value is close to the actual values found in furnaces equipped with once through burners. In furnaces equipped with swirl burners, a= 0.14 and Ff/Fb≈10. In both cases, the interval between the burners is equal to the jet diameter in the transition section d tr , which differs little from the value that has been established in practice and recommended in [7].The method traditionally used to control the furnace process in large boilers consists of equipping them with a large number of burners arranged in several tiers. Obviously, if the distance between the tiers is relatively small, operations on disconnecting or connecting them affect the entire process only slightly. A furnace design employing large flat-flame burners equipped with means for controlling the flame core position using the aerodynamic principle is a step forward. Additional possibilities for controlling the process in TPE-214 and TPE-215 boilers with a steam output of 670 t/h were obtained through the use of flat-flame burners arranged in two tiers with a large distance between the tiers; this made it possible not only to raise orlower the flame, but also to concentrate or disperse the release of heat in it [1]. A very tangible effect was obtained from installing multicell (operating on coal andopen-hearth, coke, and natural gases) flat-flame burners in the boilers of cogeneration stations at metallurgical plants in Ukraine and Russia.Unfortunately, we have to state that, even at present, those in charge of selecting the type, quantity, and layout of burners in a furnace sometimes adopt technical solutions that are far from being optimal. This problem should therefore be considered in more detail.If we increase the number of burners nb in a furnace while retaining their total cross-sectional area (ΣFb=idem) and the total flow rate of air through them, their equivalent diameters deq will become smaller, as will the jet momentums GB, resulting in a corresponding decrease in the jet throw distance Hb and the mass they eject. The space with high velocity gradients also becomes smaller, resulting in poorer mixing in the furnace as a whole. This factor becomes especially important when the emissions of Box and CO are suppressed right inside the furnace using staged combustio n (at αb < 1) under the conditions of a Fortinbras nonuniform distribution of fuel among the burners.In [1], a quantitative relationship was established between the parameters characterizing the quality with which once through jets mix with one another as they flow into a limited space with the geometrical parameter of concentration = with nb = idem and GB = idem. By decreasing this parameter we improve the mass transfer in the furnace; however, this entails an increase in the flow velocity and the expenditure of energy (pressure drop) in the burners with the same Fb. At the same time, we know from experience and calculations that good mixing in a furnace can be obtained without increasing the head loss if we resort to large long-range jets. This allows a much less stringent requirement to be placed on the degree of uniformity with which fuel must be distributed among the burners. Moreover, fuel may in this case be fed to the furnace location where it is required from process control considerations.For illustration purposes, we will estimate the effect the number of burners has on the mixing in a furnace at = = idem. schematically shows the plan views of two furnace chambers differing in the number of once through round nozzles (two andfour) placed in a tier (on one side of the furnace). The furnaces have the same total outlet cross-sectional areas of the nozzles (ΣF b) and the same jet velocities related to these areas (wb). The well-known swirl furnace of the TsKTI has a design close to the furnace arrangement under consideration. According to the data of [1], the air fraction βair that characterizes the mixing and enters through once through burners into the furnace volume beneath them can be estimated using the formula βair = 1 – (3) which has been verified in the range = 0.03–0.06 for a furnace chamber equipped with two frontal once through burners. Obviously, if we increase the number of burners by a factor of 2, their equivalent diameter, the length of the initial section of jets S0 and the area they “serve” will reduce by a factor of Then, for example, at = 0.05, the fraction βair will decrease from 0.75 to 0.65. Thus, Eq. (3) may be written in the following form for approximately assessing the effect of once through burners on the quality of mixing in a furnace:βair = 1 – 3.5f nb ' ,where is the number of burners (or air nozzles) on one wall when they are arranged in one tier both in onesided and opposite manners.The number of burners may be tentatively related to the furnace depth af (at the same = idem) using the expression (5)It should be noted that the axes of two large opposite air nozzles ( = 1)—an arrangement implemented in an inverted furnace—had to be inclined downward by more than 50° [8].One well-known example of a furnace device in which once through jets are used to create a large vortex covering a considerable part of its volume is a furnace with tangentially arranged burners. Such furnaces have received especially wide usein combination with pulverizing fans. However, burners with channels having a small equivalent diameter are frequently used for firing low-calorific brown coals with high content of moisture. As a result, the jets of air-dust mixture and secondary air that go out from their channels at different velocities(w2/w1 = 2–3) become turbulence and lose the ability to be thrown a long distance; as a consequence, the flame comes closer to the water walls and the latter are contaminated with slag. One method by which the tangential combustion scheme can be improved consists of organizing the so-called concentric admission of large jets of air-dust mixture and secondary air with the fueland air nozzles spaced apart from one another over the furnace perimeter, accompanied by intensifying the ventilation of mills [9, 10]. Despite the fact that the temperature level in the flame decreases, the combustion does not become less stable because the fuel mixes with air in a stepwise manner in a horizontal plane.V ortex furnace designs with large cortices the rotation axes of which are arranged transversely with respect to the main direction of gas flow have wide possibilities in terms of controlling the furnace process. In [1], four furnace schemes with a controllable flame are described, which employ the principle of large jets colliding with one another; three of these schemes have been implemented. A boiler with a steam capacity of 230 t/h has been retrofitted in accordance with one of these schemes (with an inverted furnace) . Tests of this boiler, during which air-dust mixture was fed at a velocity of 25–30 m/s from the boiler front using a high concentration dust system, showed that the temperature of gases at the outlet from the furnace had a fairly uniform distribution both along the furnace width and depth . A simple method of shifting the flame core over the furnace height was checked during the operation of this boiler, which consisted of changing the ratio of air flow rates through the front and rear nozzles;this allowed a shift to be made from running the furnace in adry-bottom mode to a slag-tap mode and vice Versace. A bottom-blast furnace scheme has received rather wide use in boilers equipped with different types of burners and mills. Boilers with steam capacities ranging from 50 to 1650 t/h with such an aerodynamic scheme of furnaces manufactured by ZiO and Bergomask have been installed at a few power stations in Russia and abroad . We have to point out that, so far as the efficiency of furnace process control is concerned, a combination of the following two aerodynamic schemes is of special interest: the inverted scheme and the bottom-blast one. The flow pattern and a calculation analysis of the furnace process in such a furnace during the combustion of lean coal are presented in [13].Below, two other techniques for controlling the furnace process are considered. Boilers with flame–stoker furnaces have gained acceptance in industrial power engineering, devices that can be regarded to certain degree as controllable ones owing to the presence of two zones in them . Very different kinds of fuel can be jointly combusted in these furnaces rather easily. An example of calculating such a furnacedevice is given in [2]. As for boilers of larger capacity, work on developing controllable two-zone furnaces is progressing slowly . The development of a furnace device using the so-called VIR technology (the transliterated abbreviation of the Russian introduction, innovation, and retrofitting) can be considered as holding promise in this respect. Those involved in bringing this technology to the state of industry standard encountered difficulties of an operational nature (the control of the process also presented certain difficulties). In our opinion, these difficulties are due to the fact that the distribution of fuel over fractions can be optimized to a limited extent and that the flow in the main furnace volume has a rather sluggish aerodynamic structure. It should also be noted that the device for firing the coarsest fractions of solid fuel in a spouting bed under the cold funnel is far from being technically perfect.Centrifugal dust concentrators have received acceptance for firing high-reactive coals in schemes employing pulverizing fans to optimize the distribution of fuel as to its flow rate and fractions. The design of one such device is schematically shown in [9]. Figure shows a distribution of fuel flow rates among four tiers of burners that is close to the optimum one. This distribution can be controlled if we furnish dust concentrators with a device with variable blades, a solution that has an adequate effect on the furnace process.燃煤锅炉的燃烧进程控制存在于火电厂的市场的燃料供应，某些操作参数需要改变（或保留）的情况下，以及经济和环境方面倾向的要求使他们变得更加严格的不稳定趋势是导致使控制燃烧与传热过程炉设备非常紧迫的主要因素。

毕业设计外文翻译题目（外文）：Electric boiler temperature control system题目（中文）：电锅炉温度控制系统出处：信息技术（Information technology）可以说，二十世纪跨越了三个“电”的时代，即电气时代、电子时代和现已进入的电脑时代。

不过，这种电脑，通常是指个人计算机，简称PC机，它由主机、键盘、显示器等组成。

还有一类计算机，大多数人却不怎么熟悉。

这种计算机就是把智能赋予各种机械的单片机（亦称微控制器）。

顾名思义，这种计算机的最小系统只用了一片集成电路，即可进行简单运算和控制。

因为它体积小，通常都藏在被控机械的“肚子”里。

它在整个装置中，起着有如人类头脑的作用，它出了毛病，整个装置就瘫痪了。

现在，这种单片机的使用领域已十分广泛，如智能仪表、实时工控、通讯设备、导航系统、家用电器等。

各种产品一旦用上了单片机，就能起到使产品升级换代的功效，常在产品名称前冠以形容词——“智能型”，如智能型洗衣机等。

现在有些工厂的技术人员或其它业余电子开发者搞出来的某些产品，不是电路太复杂，就是功能太简单且极易被仿制。

究其原因，可能就卡在产品未使用单片机或其它可编程逻辑器件上。

单片机的基本组成是由中央处理器（即CPU中的运算器和控制器）、只读存贮器（通常表示为ROM）、读写存贮器（又称随机存贮器通常表示为RAM）、输入/输出口（又分为并行口和串行口，表示为I/O口）等等组成。

实际上单片机里面还有一个时钟电路，使单片机在进行运算和控制时，都能有节奏地进行。

另外，还有所谓的“中断系统”，这个系统有“传达室”的作用，当单片机控制对象的参数到达某个需要加以干预的状态时，就可经此“传达室”通报给CPU，使CPU根据外部事态的轻重缓急来采取适当的应付措施。

1.单片机单片机即单片微型计算机，是把中央处理器、存储器、定时/计数器、输入输出接口都集成在一块集成电路芯片上的微型计算机。

工业锅炉节能中英文资料外文翻译文献专业英文资料Boiler energy savingIndustrial boiler energy saving technology related to many, what is the most important increase industrial furnace thermal utilization ratio of pot namely, increasing the thermal efficiency of the industrial boiler. This section from burning, transportation line maintenance, new technology and new equipment and the application of the industrial boiler auxiliary equipment of energy saving, pot boiler water processing, etc and the industrial boiler room way of energy saving is discussed in this paper.1. The furnace of industrial boiler furnace arch arch is very important. The role is to make arch furnace chamber of the mixture of gases and radiation and hot gas organization flow, to make the fuel and ignition and combustion when. Sua and at present industrial boiler with the actual YongQiLiang rated load are often not with horse, the use of coal changes greatly, and often have large design coal poor vision, so in actual use, often to furnace necessary improvement in arch coal need to be comfortable.For transformation of the former furnace arch situation, the existing problem is: for the use of coal and coal than design poor miscellaneous, boiler flue gas temperature appear the chamber exports low (about 700℃), more than 200 ℃ design low. The new coal fire late, often appear fire bed broken fire, fire from about 0.6 ~ coal disc 1 cm, furnace combustion is not strong, ash high carbon content. According to the problems furnace arch structure, from improving the ignition of fuel conditions and raise the temperature of boiler furnace to reform.After improvement furnace arch, in actual shipped in from the observed, the transformation effect is good, people away from coal furnace fuel after disc 0.3 MRP on fire, fire bed combustion intense, flame full of degree good, strong rotation. Due to the lower arch before, after extended arch, the arch of the throat and mouth shape between into space from the original 2 cm or so down to 1 cm. To strengthen the disturbance of the air mixed, to form the airflow, strengthen the furnace combustion, improve the efficiency of the district and the whole arch before furnace temperature, make its reach to 1400℃ above, improved the ignition of fuel conditions. Coal in the ignition, of furnace temperature rise, make the carbon content and ash significantly less. The flue gas mixture and strengthen the hydrocyclone separation of flue gas carbon particles needed to fall in the fire bed and new fuel layer further burns out.2. The reasonable air supply and regulationIn the chain furnace, the furnace, the furnace of reciprocating vibration, according to the different characteristics of the combustion process, reasonable air supply, to promote the furnace combustion is very important. As in the chain furnace, along with fuel keep movement, which in turn happen on fire, burning, and burn the stage. Burning along the length direction is the stoker stages, zoning, so along the length direction along the air quantity is also different. The preheating zone along the head and tail burn stage, air requirements small; The burning along the middle stage, air requirements. According to this13characteristic, must use block supply air, to meet the needs of the burning. The current domestic production of the boiler although all are to consider this one characteristic, with the wind in subsection room, and equipped with air inlet adjustment. But according to the survey.3.The secondary airSecond wind to strengthen the air combustion is very effective. Second wind have the following function:(1) strengthen the furnace of air disturbance and mixed, make the furnace of oxygen and flammable gas mixture evenly, make chemical don't fully burning loss and the chamber excess air coefficient reducing. (2) secondary air in furnace flue gas vortex formed, on the one hand, extended the suspension fine coal grain in the chamber of a stroke, increase the fine particles suspended furnace in the residence time of, make it have a full time to burn, make not complete combustion heat loss; Another result of air separation of spiral effect, make coal dust grain and the grain re-blows rejection within, and reduce the small fly ash escape from the quantity, the mechanical incomplete combustion heat loss.英译汉14锅炉的节能工业锅炉的节能技术涉及多方面 , 最主要是提高工业锅炉的热能利用率 , 即提高工业锅炉的热效率。

煤质变化对锅炉燃烧的影响及应对措施贾海洋（河北工程大学科信学院，邯郸市，056038）摘要：目前，随着国内市场上煤炭价格的一路高歌猛进，对于燃煤的火电机组来说运行成本越来越来越高，很多电厂因此败下阵来。

各个电厂都在紧锣密鼓地进行着节能工作，尽可能地减少运行成本。

本文通过分析煤炭的燃烧过程、链条炉排的燃烧特点及其对煤质的要求以及煤质不同成分对锅炉燃烧的影响，提出了在煤质发生变化时的应对措施，来保证供热质量达标和安全平稳运行。

关键词：煤质；锅炉；燃烧；应对措施COAL CHANGE ON BOILER COMBUSTION INFLUENCE AND MEASURESJIA Haiyang(Kexin College Of Hebei Engineering University, Handan, 056038)Abstract:At present, the domestic market on coal price for all unconventional, coal-fired power units for the operation cost more and more higher, many power plants so hounest conviction. Each power plant are underway for energy conservation, as far as possible to reduce operation costs. Through analysis of coal combustion process, chain of combustion characteristics of quality of coal and coal quality requirements and different ingredients on the boiler combustion, puts forward the influence of coal changed when measures, to ensure quality and safety heating running smoothly.Keywords: Coal; Boiler; Combustion; Measures0 导言：近年来由于煤炭行业矿难频发，国家对煤矿的整顿进一步加大力度，随着我国内地一些小煤矿的关停，火电厂煤炭供应日趋紧张，煤源由原来单一的优质煤转向为以贫煤，焦煤为主的煤，煤炭质量较以往有很大的变化，煤种杂、煤质差，煤种质量严重偏离锅炉的设计煤种，引发了各供热车间司炉工劳动强度明显加大，锅炉及辅助设备故障显著增加，职工工作环境有所恶化，环境保护工作难度更加突出，造成锅炉燃烧运行困难，锅炉出口温度不能达标，严重影响了锅炉的正常供热。

燃煤锅炉外文翻译外文文献英文文献中英翻译外文出处: A. A. Shatil’, N. S. K. A. A. S., & V. Kudryavtsev, A. (2008). Controllingthe furnace process in coal-fired boilers. Thermal Engineering, 55, 1, 72-77.Controlling the Furnace Process in Coal-Fired BoilersThe unstable trends that exist in the market of fuel supplied to thermal power plants and the situations in which the parameters of their operation need to be changed (or preserved), as well as the tendency toward the economical and environmental requirements placed on them becoming more stringent, are factors that make the problem ofcontrolling the combustion and heat transfer processes in furnace devices very urgent. The solution to this problem has two aspects. The first involves development of a combustion technology and,accordingly, the design of a furnace device when new installations are designed. The second involves modernization of already existing equipment. In both cases,the technical solutions being adopted must be properly substantiated with the use of both experimental and calculationstudies.The experience Central Boiler-Turbine Institute Research and Production Association (TsKTI) and ZiO specialists gained from operation of boilers and experimental investigations they carried out on models allowed them to propose several new designs of multifuel andmaneuverable—in other words, controllable—furnace devices that had been put in operationat power stations for several years. Along with this, an approximate zero-one-dimensional, zonewise calculation model of the furnace process in boilers had been developed at the TsKTI, which allowed TsKTI specialists to carry out engineering calculations of the main parameters of this process and calculate studies of furnaces employing different technologies of firing and combustion modes .Naturally, furnace process adjustment methods like changing the air excess factor, stack gas recirculation fraction, and distribution offuel and air among the tiers of burners, as well as other operations written in the boiler operational chart, are used during boiler operation.However, the effect they have on the process is limited in nature. On the other hand, control of the furnace process in a boiler implies the possibility of making substantial changes in the conditions under which the combustion and heat transfer proceed in order to considerably expand the range of loads, minimize heat losses, reduce the extent to which the furnace is contaminated with slag, decrease the emissions of harmful substances, and shift to another fuel. Such a control can be obtained by making use of the following three main factors:(i) the flows of oxidizer and gases being set to move in the flamein a desired aerodynamic manner;1(ii) the method used to supply fuel into the furnace and the placeat which it is admitted thereto;(iii) the fineness to which the fuel is milled.The latter case implies that a flame-bed method is used along withthe flame method for combusting fuel.The bed combustion method can be implemented in three design versions: mechanical grates with a dense bed, fluidized-bed furnaces, and spouted-bed furnaces.As will be shown below, the first factor can be made to work bysetting up bulky vortices transferring large volumes of air and combustion products across and along the furnace device. If fuel isfired in a flame, the optimal method of feeding it to the furnace is to admit it to the zones near the centers of circulating vortices, a situation especially typical of highly intense furnace devices. The combustion process in the se zones features a low air excess factor (α< 1) and a long local time for which the components dwell in them, factors that help make the combustion process more stable and reduce theemission of nitrogen oxides .Also important for the control of a furnace process when solid fuelis fired is the fineness to which it is milled; if we wish to minimize incomplete combustion, the degree to which fuel is milled should be harmonized with the location at which the fuel is admitted into the furnace and the method for supplying it there, for the occurrence of unburned carbon may be due not only to incomplete combustion of large-size fuel fractions, but also due to fine ones failing to ignite (especially when the content of volatiles Vdaf < 20%).Owing to the possibility of pictorially demonstrating the motion of flows, furnace aerodynamics is attracting a great deal of attention of researchers and designers who develop and improve furnace devices. At the same time, furnace aerodynamics lies at the heart of mixing (mass transfer), a process the quantitative parameters of which can be estimated only indirectly or by special measurements. The quality with which components are mixed in the furnace chamber proper depends on the number, layout, and momenta of the jets flowing out from individual burners or nozzles, as well as on their interaction with the flow of flue gases, with one another, or with the wall.It was suggested that the gas-jet throw distance be used as a parameter determining the degree to which fuel is mixed with air in the gas burner channel. Such an approach to estimating how efficient the mixing is may to a certain degree be used in analyzing the furnace as a mixing apparatus. Obviously, the greater the jet length (and its momentum), the longer the time during which the velocity gradient it creates in the furnace will persist there, a parameter that determines how completely the flows are mixed in it. Note that the higher the degree to which a jet is turbulized at the outlet from a nozzle or burner, the shorter the distance which it covers, and, accordingly, the less completely the components are mixed in2the furnace volume. Once through burners have advantages over swirl ones in this respect.It is was proposed that the extent to which once through jets are mixed as they penetrate with velocity w2 and density ρ2 into a transverse (drift) flow moving with velocity w1 and having density ρ1 be correlated with the relative jet throw distance in the following way Where ks is a proportionality factor tha t depends on the ―pitch‖ between the jet axes (ks=1.5–1.8).The results of an experimental investigation inwhich the mixing of gas with air in a burner and then in a furnace was studied using the incompleteness of mixing as a parameter are reported in 5.A round once through jet is intensively mixed with the surrounding medium in a furnace within its initial section, where the flow velocity at the jet axis is still equal to the velocity w2 at the nozzle orifice of radius r0.The velocity of the jet blown into the furnace drops very rapidly beyond the confines of the initial section, and the axis it has in the case of wall-mounted burners bends toward the outlet from the furnace.One may consider that there are three theoretical models for analyzing the mixing of jets with flowrate G2 that enter into a stream with flowrate G1. The first model is for the case when jets flow into a ―free‖ space (G1= 0),the second model is for the case when jets flowinto a transverse (drift) current with flowrate G1G2，and the third model is for the case ,when jets flow into a drift stream with flowrate G1<G2. The second model represents mixing in the channel of a gas burner, and the third model represents mixing in a furnace chamber. We assume that the mixing pattern we have in a furnace is closer to the first model than it is to the second one, since 0 <G1/G2< 1, and we will assume that the throw distance h of the jet being drifted is equal to the length S0 of the―free‖ jet’s initial section. The ejection ability of the jet being drifted then remains the same as that of the ―free‖ jet, and the length of the initialsection can be determined using the well-known empirical formula of G.N. Abramovich [6] :S0= 0.67r0/a, (2)where a is the jet structure factor and r0 is the nozzle radius.At a = 0.07, the length of the round jet’s initial section is equal to 10 r0 and the radius the jet has at the transition section (at the end of the initial section) is equal to 3.3 r0. The mass flowrate in the jet is doubled in this case. The corresponding minimum furnace cross-sectional area Ff for a round once through burner with the outlet cross-sectional area Fb will then be equal to and the ratio Ff/Fb?20. This value is close to the actual values found in furnacesequipped with once through burners. In furnaces equipped with swirl burners, a= 0.14 and Ff/Fb?10. In both cases, the interval between theburners is equal to the jet diameter in the transition section d tr , which differs little from the value that has been established inpractice and recommended in [7].3The method traditionally used to control the furnace process inlarge boilers consists of equipping them with a large number of burners arranged in several tiers. Obviously, if the distance between the tiers is relatively small, operations on disconnecting or connecting themaffect the entire process only slightly. A furnace design employinglarge flat-flame burners equipped with means for controlling the flame core position using the aerodynamic principle is a step forward. Additional possibilities for controlling the process in TPE-214 and TPE-215 boilers with a steam output of 670 t/h were obtained through the use of flat-flame burners arranged in two tiers with a large distance between the tiers; this made it possible not only to raise or lower the flame, but also to concentrate or disperse the release of heat in it [1].A very tangible effect was obtained from installing multifuel (operating on coal and open-hearth, coke, and natural gases) flat-flame burners in the boilers of cogeneration stations at metallurgical plants in Ukraine and Russia.Unfortunately, we have to state that, even at present, those in charge of selecting the type, quantity, and layout of burners in a furnace sometimes adopt technical solutions that are far from being optimal. This problem should therefore be considered in more detail.If we increase the number of burners nb in a furnace while retaining their total cross-sectional area (ΣFb=idem) and the total flowrate ofair through them, their equivalent diameters deq will become smaller, as willthe jet momentums Gbwb, resulting in a corresponding decrease in the jet throw distance hb and the mass they eject. The space with high velocity gradients also becomes smaller, resulting in poorer mixing in the furnace as a whole. This factor becomes especially important whenthe emissions of NOx and CO are suppressed right inside the furnaceusing staged combustion (at αb < 1) under the conditionsof a fortiori nonuniform distribution of fuel among the burners.In [1], a quantitative relationship was established between the parameters characterizing the quality with which once through jets mix with one another as they flow into a limited space with the geometrical parameter of concentration = with nb = idem and Gb = idem. By decreasing this parameter we improve the mass transfer in the furnace; however,this entails an increase in the flow velocity and the expenditure of energy (pressure drop) in the burners with the same Fb. At the same time, we know from experience and calculations that good mixing in a furnace can be obtained without increasing the head loss if we resort to large long-range jets. This allows a much less stringent requirement to be placed on the degree of uniformity with which fuel must be distributed among the burners. Moreover, fuel may in this case be fed to the furnace location where it is required from process control considerations.For illustration purposes, we will estimate the effect the number of burners has on the mixing in a furnace at = = idem. schematically shows the plan views of two furnace chambers4differing in the number of once through round nozzles (two and four) placed in a tier (on one side of the furnace). The furnaces have the same total outlet cross-sectional areas of the nozzles (ΣFb) and the same jet velocities related to these areas (wb). The well-known swirl furnace of the TsKTI has a design close to the furnace arrangement under consideration. According to the data of [1], the air fraction βair that characterizes the mixing and entersthrough once through burners into the furnace volume beneath themcan be estimated using the formula βair = 1 – (3) which has been verified in the range = 0.03–0.06 for a furnacechamber equipped with two frontal once through burners. Obviously,if we increase the number of burners by a factor of 2, their equivalent diameter, the length of the initial section of jets S0 and the area they ―serve‖ will reduce by a factor of Then, for example, at = 0.05, the raction βair will decreas e from 0.75 to 0.65. Thus, Eq. (3) may be written in the following fform for approximately assessing the effect of once through burners on the quality of mixing in a furnace:βair = 1 – 3.5f nb ' ,where is the number of burners (or air nozzles) on one wall when they are arranged in one tier both in onesided and opposite manners.The number of burners may be tentatively related to the furnacedepth af (at the same = idem) using the expression (5)It should be noted that the axes of two large opposite air nozzles ( = 1)—an arrangementimplemented in an inverted furnace—had to be inclined downward by more than 50? [8].One well-known example of a furnace device in which once throughjets are used to create a large vortex covering a considerable part of its volume is a furnace with tangentially arranged burners. Such furnaces have received especially wide use in combination with pulverizing fans. However, burners with channels having a small equivalent diameter are frequently used for firing low-calorific brown coals with high content of moisture. As a result, the jets of air-dust mixture and secondary air that go out from their channels at different velocities(w2/w1 = 2–3) become turbulized and lose the ability to be thrown a long distance; as a consequence, the flame comes closer to the waterwalls and the latter are contaminated with slag. One method by which the tangential combustion scheme can be improved consists of organizing the so-called concentric admission of large jets of air-dust mixture and secondary air with the fuel and air nozzles spaced apart from one another over the furnace perimeter, accompanied by intensifying the ventilation of mills [9, 10]. Despite the fact that thetemperature level in the flame decreases, the combustion does not become less stable because the fuel mixes with air in a stepwise manner in a horizontal plane.Vortex furnace designs with large vortices the rotation axes ofwhich are arranged transversely with respect to the main direction of gas flow have wide possibilities in terms of5controlling the furnace process. In [1], four furnace schemes with a controllable flame are described, which employ the principle of large jets colliding with one another; three of these schemes have been implemented. A boiler with a steam capacity of 230 t/h has been retrofitted in accordance with one of these schemes (with an inverted furnace) . Tests of this boiler, during which air-dust mixture was fed at a velocity of 25–30 m/s from the boiler frontusing a highconcentration dust system, showed that the temperatureof gases at the outlet from the furnace had a fairly uniformdistribution both along the furnace width and depth . A simple method of shifting the flame core over the furnace height was checked during the operation of this boiler, which consisted of changing the ratio of air flowrates through the front and rear nozzles;this allowed a shift to be made from running the furnace in a dry-bottom mode to a slag-tap mode and vice versa. A bottom-blast furnace scheme has received rather wide use in boilers equipped with different types of burners and mills. Boilers with steam capacities ranging from 50 to 1650 t/h with such anaerodynamic scheme of furnaces manufactured by ZiO and Sibenergomash have been installed at a few power stations in Russia and abroad . We have to point out that, so far as the efficiency of furnace process control is concerned, a combination of the following two aerodynamic schemes is of special interest: the inverted scheme and the bottom-blast one. The flow pattern and a calculation analysis of the furnace process in such a furnace during the combustion of lean coal are presented in [13].Below, two other techniques for controlling the furnace process are considered. Boilers with flame–stoker furnaces have gained acceptancein industrial power engineering, devices that can be regarded to certain degree as controllable ones owing to the presence of two zones in them . Very different kinds of fuel can be jointly combusted in these furnaces rather easily. An example of calculating such a furnace device is given in [2]. As for boilers of larger capacity, work on developing controllable two-zone furnaces is progressing slowly . The development of a furnace device using the so-called VIR technology (thetransliterated abbreviation of the Russian introduction, innovation, and retrofitting) can be considered as holding promise in this respect. Those involved in bringing this technology to the state of industry standard encountered difficulties of an operational nature (the control of the process also presented certain difficulties). In our opinion, these difficulties are due to the fact that the distribution of fuel over fractions can be optimized to a limited extent and that the flow inthe main furnace volume has a rather sluggish aerodynamic structure. It should also be noted that the device for firing the coarsest fractions of solid fuel in a spouting bed under the cold funnel is far from being technically perfect.Centrifugal dust concentrators have received acceptance for firing high-reactive coals in schemes employing pulverizing fans to optimize the distribution of fuel as to its flowrate and6fractions. The design of one such device is schematically shown in [9]. Figure shows a distribution of fuel flowrates among four tiers of burners that is close to the optimum one. This distribution can be controlled if we furnish dust concentrators with a device with variable blades, a solution that has an adequate effect on the furnace process.7燃煤锅炉的燃烧进程控制存在于火电厂的市场的燃料供应，某些操作参数需要改变(或保留)的情况下，以及经济和环境方面倾向的要求使他们变得更加严格的不稳定趋势是导致使控制燃烧与传热过程炉设备非常紧迫的主要因素。

电厂锅炉英文文献以下是一篇关于电厂锅炉的英文文献，供参考：Title: Boiler in Power Plant - A ReviewAbstract:Boilers play a crucial role in power plants, providing steam for electricity generation. This paper reviews the various types of boilers used in power plants, their working principle, and the challenges faced in their operation. It also discusses the importance of efficient boiler performance in ensuring reliable power generation.Introduction:Power plants heavily rely on boilers for steam generation, which in turn drives the turbines to generate electricity. Boiler technology has evolved significantly over the years, with advancements in efficiency, reliability, and environmental friendliness. This review provides a comprehensive overview of boiler technology in power plants, highlighting the key components and their functions. Types of Boilers:There are several types of boilers used in power plants, including pulverized coal-fired boilers, circulating fluidized bed boilers, and supercritical boilers. Each type has its unique characteristics and advantages. Pulverized coal-fired boilers are the most common type, where coal is ground into fine particles and burned in a furnace to produce steam. Circulating fluidized bed boilers use a bed of sand and fuel particles to achieve efficient combustion. Supercritical boilers operate at high pressures and temperatures toimprove efficiency.Working Principle:Boilers operate on the principle of heat transfer from the combustion of fuel to the working fluid, typically water or steam. Fuel is burned in the furnace, generating heat that is transferred to the water/steam in the boiler tubes. The heat transfer process is facilitated by convection and radiation. The resulting steam is then used to drive the turbines for electricity generation.Challenges in Boiler Operation:Boiler operation faces several challenges, including maintaining high efficiency, controlling emissions, and ensuring safety. Efficiency is crucial as it directly impacts the overall power plant performance. Design and operational factors affect boiler efficiency, and continuous monitoring and optimization are required to maximize efficiency. Emission control is also a significant challenge, as power plants are subject to strict environmental regulations. Lastly, safety considerations are paramount to prevent accidents and ensure the well-being of personnel.Conclusion:Boilers are vital components in power plants, responsible for steam generation and subsequently electricity production. Understanding the different types of boilers, their working principles, and the challenges in their operation is essential for efficient and reliable power generation. Ongoing research and development in boiler technology aim to further improve efficiency, reduce emissions, and enhance safety in power plant operations.。

锅炉专业英语中英文对照表火道锅炉Flame tube boiler疏水器、疏水阀steam trap饱和蒸汽saturated steam过热蒸汽superheated steam震动炉篦Oscillating bar grate链条炉蓖Chain grate, travelling grate省煤器economizer减速器speed reducer螺旋除渣机screw slag remover除尘器dust collectorcombustion air fan鼓风机exhausting fan上煤机coal conveyor尖端的、高科技的Hi-tech节能的energy-saving高效的high-efficiency低噪声的low noise耐用的、持久的durable蒸发evaporation额定的rated热效率thermal efficiency碳化物carbide碳化硅silicon carbidemonoxide一氧化碳carbon monoxide二氧化碳dioxide二氧化碳亚临界压力锅炉carbon dioxide subcritical pressure boiler燃煤锅炉coal-fired boiler启动锅炉 start-up boiler炉墙 furnace wall管束（排） tube bundle管屏tube platen下降管 downcomer上升管 riser省煤器管 economizer tube再热器管 reheater tube过热器管 superheated tube蛇形管 coil吊挂管 supporting tube水冷壁管 water wall tubesaturated steam pipe水冷壁 water wall鳍片管finned tube, fin tube, gilled tube 联箱 header锅炉本体 boiler proper锅炉机组 boiler unit炉膛 boiler framework燃烧器 furnace燃烧室 combustion chamber油枪 oil gun torch风门 damper管板 tube plate。

成绩：《文献检索与利用》实习报告论文题目：锅炉过热器姓名：陈磊班级：热动11301学号: 201124240141授课教师：于澄洁一、课题名称：中文题名：锅炉过热器英文题名：Boiler Superheater中文关键词：过热器英文关键词：Superheater二、课题概述：（约200～300字）锅炉过热器是把饱和蒸汽加热到额定过热温度的锅炉受热面部件。

回收锅炉烟气能量，使锅炉出来的蒸汽可以获得加热，变为干蒸汽，有利于提高锅炉热效率，也有利于蒸汽轮机避免水击。

过热器可根据布置位置和传热方式分为几类，一、对流式过热器，二、屏式过热器，三、辐射式过热器，四、炉顶过热器与包墙管过热器工业锅炉的过热器均为对流式过热器，现代大型电站锅炉的过热器则常由对流式，半辐射式和辐射式过热器组成。

三、《中国学术期刊全文数据库》（）列举出部分检索结果（含摘要）。

1、锅炉过热器动态特性数理分析及其状态观测器的鲁棒性【作者中文名】韩忠旭【作者英文名】HAN Zhong-xu~(1,2) (1.China Electric Power Research Institute, Beijing 1000 85, China; 2. Beijing Stage Power Zhishen Control Technology Ltd. Beijing 100085, China) 【机构】中国电力科学研究院北京100085 北京国电智深控制技术有限公司；北京100085；【摘要】该文以过热器蒸汽温度受控对象为例,剖析了单相受热管焓-温通道的几种集总参数数学模型,它们共同的特性是特征方程的解均为实数根,从而具有过阻尼的性质。

在此基础上,进一步揭示应用高阶等容惯性环节作为锅炉过热器蒸汽温度受控对象的状态观测器这一方法内在的数学与物理基础,进而得出在设计锅炉过热器蒸汽温度受控对象的状态观测器时,不必受对象阶数的限制,通过调整观测器的参数,同样可以很好地完成重构状态并进行极点配置,起到改善受控系统动态特性的设计效果。

英文文献翻译1；文献原文(1)Coal-Fired, Circulating Fluidized-Bed Boilers in ActionElectric utilities burning coal continueto search for cost-effective ways toincrease electricity generation whilestill meeting increasingly stringent emissionstandards. Over the last several years,fluidized-bed combustion has emerged as aviable option. One company with significant experience in the area of industrial andutility boiler design has developed a compact atmospheric internal recirculation circulating fluidized-bed (IR-CFB) boiler forcommercial application.Performance data for Babcock & WilcoxIR-CFB installations at Southern IllinoisUniversity (SIU) and an industrial facility inIndia are reported in a recent paper preparedby S. Kavidass and Mikhail Maryamchik ofBabcock & Wilcox (Barberton, Ohio),C. Price of SIU (Carbondale, Illinois), andA. Mandal of Kanoria Chemicals & Industries Ltd. (Renukoot, India). The paper, entitled ―B&W’s IR-CFB Coal-Fired BoilerOpe rating Experiences,‖ was presented atthe Fifteenth Annual International Pittsburgh Coal Conference, held September 14–18, 1998 inPittsburgh, Pennsylvania.IR-CFB Boiler DesignIn a fluidized-bed boiler, crushed coal isintroduced into a furnace containing a bedof either an inert material (like sand orcrushed limestone) or dolomite. Pressurizedair, fed into the bottom of the furnace, blowsupward through the bed and causes the coaland bed materials to ―fluidize‖ in a highlyturbulent, suspended state. Figure 1 profilesa typical IR-CFB furnace, demonstrating thechange in bed density with increasingheight. The turbulence of the fluidized-bedsystem allows prolonged contact betweenthe air and the particles of coal, resulting inmore complete combustion at a lower temperature than older systems (which reducesnitrogen oxides). If sorbent material such aslimestone is used as bed material, emissionsof sulfur dioxide are likewise reduced due toconversion to calcium sulfate. Further, because combustion occurs at a lower temperature, the process is relatively insensitiveto the type of fuel burned. This allows theuse of alternative fuels such as coal waste,biomass fuels, petroleum coke, and otherlower British thermal unit (Btu) material.A circulating fluidized bed captures thesolids carried out of the furnace and returnsthem to the primary combustion chamber.This recycling feature increases the fuel residence time in the furnace, which increasescombustion efficiency. The Babcock &Wilcox IR-CFB boiler provides two stagesof solids recirculation, maximizing fuelburnout and sulfur capture. Also, designvelocities at the furnace exit are relativelylow, which significantly reduces erosion ofthe upper furnace and primary solids separator.Unique Design FeaturesOne of the features of Babcock & Wilcox’s IR-CFB design is the use of a U-beamsolids separation system. As shown in Figure 2, the U-beam system consists of rowsof U-shaped vertical rods attached to theroof of the furnace that interrupt the flow ofthe gases exiting the furnace. Two rows ofU-beams are placed inside the furnace itself,and four rows of U-beams are installed behind the furnace rear wallplane. The in-furnace U-beams capture about 75% of thesolids, which slide down the length of thebeams back into the combustion chamber.The remaining solid particles captured in theexternal U-beams are collected in a particlestorage hopper, which is periodically emptied back into the furnace forreburning.Theflue gas velocity across the U-beams isaround 8 meters/second (26.5 ft/sec) or less,producing a relatively low gas-side pressuredrop (less than 1 inch of water column) ascompared to conventional cyclone-typeseparators (6 to 10 inches of water column).The IR-CFB furnace is made of gas-tightmembrane enclosure water-cooled wallswith studded tubing spaced every fourinches. The lower furnace walls (up to aheight of 7.3 meters [24 ft]) are protectedwith an ultra high-strength, abrasion-resistant, low-cement refractory material lessthan 1 inch in thickness, which is placedover the studs protruding from the coolingtubes. A band of metal spray is typicallyapplied to further protect against erosion atthe point where the refractory material ends.The very thin application of refractory material means faster startup and less maintenance cost.Other beneficial characteristics of the IR-CFB boiler design include:* Use of in-furnace surfaces (division andwing walls) for furnace temperature control;* Gravity fuel feed and simplified secondary ash recycle system;* Absence of hot expansion joints, allowingsignificantly reduced maintenance;* Smaller footprint, which allows retrofitinside existing structural steel.Operating Experience at Two InstallationsThe IR-CFB design has been installed attwo locations—one at SIU in Carbondale, Illinois, and the second at the KanoriaChemicals & Industries Ltd. (Kanoria) sitein Renukoot, India. The SIU installation is a35-megawatt (MW) boiler that burns high-sulfur, low-ash Illinois coal, while the 81-MW Kanoria unit uses low-sulfur, high-ashcoal. The SIU boiler has a crushed limestonebed to combat the higher sulfur content ofthe fuel, while the Kanoria boiler uses a sandbed.SIU Unit dataThe SIU boiler is located close to the OldBen II coal mine in southern Illinois. Theplant was completed in 1996 and startedoperation in mid-1997. Performance testingwas completed in September 1997. Table 1shows the design and performance data forthe SIU boiler.Raw coal, delivered by truck, is movedby drag chain conveyor to a crusher. A24-hour capacity silo stores the pulverizedcoal. The coal is introduced into the furnaceby one gravimetric feeder through the sidewall. Two 60-MMBtu/hr gas-fired, over-bed burners and two 25-MMBtu/hr gas-fired, in-bed lances provide heat for startup.A multi-cyclone dust collector is used as asecondary solids separator (downstreamfrom the U-beams). The overall solids collection efficiency exceeds 90% and solidscollected in the cyclone are returned to thefurnace via an air fluidized conveyor. Abaghouse provides final particulate control.The bed material is periodically drainedfrom the furnace to control bed solids build-up and to remove any oversized material.The SIU unit has a single 8-inchdiameterdrain pipe to remove the bed, which iscooled with a screw ash cooler using recirculated plant water supply.Cold startup to 100% maximum continuous rating (MCR) can be achieved withinfive hours and the observed boiler dynamicload response is 5%–6% per minute. Aboiler turndown of 5:1 has been achievedwithout auxiliary fuel (a turndown ratio of3.5:1 to 4:1 is guaranteed). Further, all majorequipment has performed reliably whilemeeting or surpassing permitted emissions.A soot blower installed at the horizontalconvection pass floor has experienced plugging with ash and residual moisture. Whilethe boiler can operate successfully withoutthe soot blower, more investigation isneeded to overcome this operational glitch.Kanoria Unit DataThe Kanoria facility is located within thestate of Utter Pradesh, India, in close proximity to the Singaroli coal mine. The boilerwas constructed in 1996 and began commercial operation in February 1997. Performance testing continued until September1997. Design and performance data for theKanoria boiler are also shown in Table 1.In contrast to the Illinois coal, the Kanoriafuel is erosive, low in sulfur, and high in ash.Crushed coal is introduced via two volumetric drag chain feeders through the front wallof the furnace. Two 60-MMBtu/hr oil-firedover-bed burners provide heat for startup.Solids collected by the U-beams are reinjected by gravity into the furnace at fourlocations. The Kanoria unit uses an electro-static precipitator for final particulate control. Bed draining is accomplished throughtwo bed drain pipes and ash coolers; finematerial is returned to the furnace, whileoversize particles are diverted to the ashdisposal system.The observed boiler efficiency of 88.8%is higher than originally anticipated andcombustion efficiency has exceeded 99%,due to very low unburned carbon and lowflue gas outlet temperatures. However, theerosive nature of the fuel initially causedtubing leaks in the water-cooled furnacewall, which have been remedied by applyingadditional metal spray at the refractory interface and adjusting the interface angle.Also, furnace temperature exceeded designvalue on several occasions due to insufficient upper furnace inventory caused by failures of the first fields of the electrostaticprecipitator and the ash conveying system.Adjustments to the precipitator rectifier andthe ash silo backpressure have solved theseproblems.In summary, two examples of IR-CFBboilers are successfully operating at 100%MCR with varying fuel types. IR-CFB appears reliable and incorporates several verylow-maintenance features that reduce operating costs.（2）Why Build a Circulating Fluidized Bed Boilerto Generate Steam and Electric PowerAbstractIn Asia, demand for electric power continues to rise steeplydue to population growth, economic development, and progres-sive substitution of alternate technologywith clean forms ofenergy generation. Atmospheric circulating fluidized bed (CFB)echnology has emerged as an environmentally acceptable technology for burning a wide range of solid fuels to generate steamand electricity power. CFB, although less than 20 years old, is amature technology with more than 400 CFB boilers in operation worldwide, ranging from 5 MW e to 250 MW e.Electric utilities and Independent Power Producers must nowselect a technology that will utilize a wide range of low-costsolid fuels, reduce emissions, reduce life cycle costs, and provide reliable steam generation for electric power generation.Therefore, CFB is often the preferred technology. Even thoughpulverized coal (PC) fired boilers continue to play a major roleworldwide, they have inherent issues such as fuel inflexibility,environmental concerns and higher maintenance costs.This paper discusses the benefits of CFB boilers for utilityand industrial applications. Specific emphasis is given to B&W’snternal Recirculation CFB (IR-CFB) technology, CFB technology comparisons, PC vs. CFB technology, emissions benefits,and economics including maintenance cost and boiler reliabilty. IntroductionBabcock & Wilcox (B&W) is a leading global supplier ofindustrial/utility boilers and has supplied more than 700 unitstotaling more than 270,000 MW e. Many of B&W’s CFB boilerdesign features have been adapted from vast experience designing and building boilers of all types and sizes for industrial andelectric utility applications. B&W’s design is an inherently compact, distinctive internal recirculation fluidized bed (IR-CFB)boiler featuring U-Beam solids separators. The furnace and convection pass of the IR-CFB boiler are within a single, gas–tightmembrane enclosure as commonly found in Pulverized Coal(PC) fired boilers. This CFB technology has been successfullyintroduced in the global market.To date, B&W, including B&W joint ventures and licenseecompanies, has sold 16 CFB boilers worldwide, shown in Table 1.B&W offers IR-CFB boilers up to 175 MWe, both reheat andnon-reheat, with full commercial guarantees and warranties. TheIR-CFB boiler is simple in configuration and compact, requiresa smaller boiler foot print, has minimal refractory, requires lowmaintenance, features quick startup, and provides high avail-ability.The modern way of burning solid fuels requires fuel flex-ibility and reliable technology, plus good combustion efficiencywith low emissions. CFB technology is well suited for a widerange of sold fuels. CFB technology is proven, mature and competitive.What is CFB technology?CFB technology utilizes the fluidized bed principle in whichcrushed (6 –12 mm x 0 size) fuel and limestone are injectedinto the furnace or combustor. The particles are suspended in astream of upwardly flowing air (60-70% of the total air) whichenters the bottom of the furnace through air distribution nozzles.The balance of combustion air is admitted above the bottom ofthe furnace as secondary air. While combustion takes place at840-900 C, the fine particles (<450 microns) are elutriated outof the furnace with flue gas velocity of 4-6 m/s. The particlesare then collected by the solidsseparators and circulated back into the furnace. This combustion process is called circulatingfluidized bed (CFB). The particles’ circulation provides efficient heat transfer to the furnace walls and longer residence timefor carbon and limestone utilization. Similar to PC firing, thecontrolling parameters in the CFB combustion process are temperature, residence time and turbulence.Designers and power plant operators have vast experience in PC-fired boiler design and operations. Adapting and under-standing CFB technology by those familiar with the PC environment requires time. CFB technology brings the capability ofdesigns for a wide range of fuels from low quality to high quality fuels, lower emissions, elimination of high maintenance pulverizers, low auxiliary fuel support and reduced life cycle costs.A PC vs. IR-CFB comparison is given in Table 2.The combustion temperature of a CFB (840-900 C) is muchlower than PC (1350-1500 C) which results in lower Nox for-mation and the ability to capture SO2with limestone injectionin the furnace. Even though the combustion temperature of CFBis low, the fuel residence time is higher than PC, which resultsin good combustion efficiencies comparable to PC. The PC pulverizers, which grind the coal to 70% less than 75 microns, require significant maintenance expenses. These costs are virtually eliminated in CFB because the coal is crushed to 12 - 6 mmx 0 size. Even though CFB boiler equipment is designed forrelatively lower flue gas velocities, the heat transfer coefficientof the CFB furnace is nearly double that of PC which makes thefurnace compact. In an IR-CFB, auxiliary fuel support is neededfor cold startup and operation below 25% versus 40-60% MCRwith PC. One of the most important aspects is that CFB boilers release very low levels of SO2 and NO x pollutants compared to PC, as shown in Table 2. PC units need a scrubber system, whichrequires additional maintenance.CFB is a fuel-driven and flexible technologyCFB can be the technology of choice for several reasons.The CFB can handle a wide range of fuels such as coal, wastecoal, anthracite, lignite, petroleum coke and agricultural waste,with low heating value (>1500 kcal/kg), high moisture content(< 55%), and high ash content (< 60%). The fuel flexibility provides use of opportunity fuels where uncertainty of fuel supplyexists and economics are an issue. If a CFB boiler is designedfor coal, the same boiler can be used to burn lignite or petroleum coke or anthracite. The material handling and feeding system should be properly designed to meet these fuel variations.Such fuel flexibility is not available in the competing conventional PC-fired boiler technologies. This is one of the importantfeatures of CFB that the customer needs to analyze carefullybefore selecting a technology.Environmental benefits of CFB technologyThe CFB combustion process facilitates steam generationfiring a wide range of fuels while meeting the required emissions such as sulfur dioxide (SO2 ) and nitrogen oxides (NO x)even more effectively than World Bank guidelines, as shown inTable 3.The major environmental benefit of selecting CFB technology is the removal of SO2(90-95%) and NO x(emission is lessthan 100 ppm) in the combustion process without adding postcombustion cleaning equipment such as wet or dry flue gasdesulfurization (FGD) systems and selective catalytic reduction(SCR) systems. When the limestone is injected into the furnace,the following reactions occur.* Oxidation of sulfurS+O2 --> SO2* Limestone is calcined to form calcium oxideCaCO3--> CaO + CO2–425 kcal/kg (of CaCO3 )* Sulfur dioxide gas reacts with solid CaOSO2+ 1/2 O2 + CaO --> CaSO4 (Solid) +3740 kcal/kg (of S) The resulting calcium-sulfate-based ashes are chemicallystable and are easily disposed. This ash can be used as raw material for cement manufacturing, soil stabilization, concreteblocks, road base, structural fills, etc. Limestone injection isrequired for fuels with sulfur greater than >0.5%. Lime (CaO)and unburned carbon content must be considered in re-use applications, depending on the fuel being fired.NO x present in flue gas generally comes from two sources:the oxidation of nitrogen compounds in the fuel (fuel NO x) andreaction between the nitrogen and oxygen in the combustionair (thermal NO x). With low temperature and staged combustion,the oxidation of fuel nitrogen is suppressed resulting in verylow NO x emissions. NO x emissions are <100 ppm with CFB.CO and hydrocarbon emissions in the CFB boiler are wellcontrolled. In recent years, financial institutions have pushedthe power project developers to meet the World Bank emissionsrequirements. Therefore obtaining the project permit is less difficult with CFB technology.Design features of B&W IR-CFB Boiler technologyB&W IR-CFB technology is very comparable to PC-firedboilers in arrangement. The IR-CFB boiler design consists ofthe following major systems, shown in Fig. 1. The main CFBboiler components are:* Boiler furnace* Furnace bottom air distributor and nozzles* Primary solids separators and recirculation system* Secondary solids separators and recirculation system* Pendant superheater / reheater* Economizer and horizontal tubular air heater* Air assisted gravity fuel /limestone feed systemBoiler FurnaceThe furnace cross section is selected based on flue gas superficial velocity. B&W typically uses furnace depths of 3.7 m,4.6 m and 5.4 m, depending on the unit size. The furnace enclosure is made of gas-tight membrane water-cooled walls having63.5 mm or 76 mm tube diameters on 102 mm centers. The furnace primary zone is reduced in plan area cross section to provide good mixing and promote solids entrainment at low load.The auxiliary startup burners, fuel feed points and secondaryash re-injection (multicyclone/MDC) points are located in thisregion.A thin layer of refractory is applied on all lower furnace walls,including the lower portion of the division walls and wing wallnose to protect against corrosion and erosion. An ultra highstrength abrasion-resistant low cement alumina refractory 16-25 mm thick is applied over a dense pin studded pattern. B&Whas patented aRDZ TM reduced diameter zone feature that elimihas nates erosion concern at the furnace interface. The furnace temperature is precisely controlled by maintaining proper inventory and thus the combustion efficiency and the limestone utili-zation are maximized.Air Distrbutors and NozzlesThe furnace bottom air plenum or wind box is made of water-cooled panels or casing depending on startup air temperature. Bubble caps are fitted on the water-cooled distributor floorpanels as shown in Fig. 2. The bubble caps are designed to distribute air uniformly, prevent the back sifting of solids at lowload operation, and create good turbulence for fuel /sorbentmixing in the primary zone. The bubble caps are spaced 102mm x 117 mm with 60-70% of total combustion air admittedthrough the bottom. The balance 30-40% of total air is admittedthrough overfire nozzles (high velocity) in the front and rearfurnace walls.Primary Solids SeparatorsThe solids separation system is a key element of any CFBboiler design. The B&W separation system is designed for thelife of the unit without replacement, influencing life cycle costs.The B&W IR-CFB has a two stage primary solids separator asshown in Fig. 3, comprised of in-furnace U-Beam separatorsand external U-Beam separators. The in-furnace U-Beams (tworows) are able to collect nearly 75% of the solids. The remaining solids are collected by the four rows of external U-Beamsand are discharged from the hopper directly into the furnace throughthe transfer hopper located beneath the external U-Beams (See Fig.4). The flue gas velocity across the U-Beams is approximately 8-10 m/s, limiting the gas-side pressure drop to 0.25 kPa as compared with a typical cyclone separator’s pressure drop of 1.5 to 2.0kPa. A commercially available, high-grade stainless steel materialis used for the U-Beam separators.Secondary Solids SeparatorThe multicyclone dust collector (MDC) is located in the convective pass either upstream or downstream of the economizer.The MDC typically has a top inlet and top outlet as shown inFig. 5. The MDC tube diameter is normally 229 mm arrangedover the second pass entire cross section. The MDC providesoutstanding retainment of fine particles up to 50 microns. TheMDC collection tubes and spin vanes have high hardness (550BHN), designed for longer life and easy replacement duringplanned outages.The small quantities of fines which escape from the externalU-Beams are collected by the MDC. The collected fines arestored in the MDC hopper. Variable speed rotary feeders or inclinedscrews are used to control the ash recycle flow rate fromthe hopper. Precise furnace temperature control is achieved byadjusting the speed of the rotary feeders or inclined screws, taking the temperature signal from the furnace.The superheater may consist of vertical pendant type primary and secondary banks, located in the convection pass, aswell as surface in the furnace in the form of superheater wingwalls. An attemperator is used to control the final steam temperature over the design load range. The flue gas velocities arerelatively low and selected byconsidering the dust loading andash erosivity of the fuel. When required, the reheater is locatedin the convection pass, and steam bypass is recommended tocontrol the final reheater temperature.Economizer and Horizontal Tubular air heaterThe economizer is designed with tubes running front to backin an in-line arrangement. Flue gas velocities used consider thedust loading and ash erosivity of the fuel. If the MDC is locatedupstream of the economizer, higher velocities are used and boththe economizer and the air heater are located in an in-line arrangement to minimize ash fouling. The air heater is locatedafter the MDC and the economizer. The flue gas is outside thetubes and air is passed through the tubes. A hopper is providedat the bottom of the air heater and the ash collected in the hopper is purged to the ash disposal system. The tube material andflue gas velocities are selected by considering the dust loadingand the ash erosivity of the fuel. A steam coil air heater (SCAH)is used to protect the cold end of the air heater if required.Air-Assisted Gravity Fuel/Limestone Feed SystemFuel handling and feeding is one of the major challenges inCFB boiler operation, especially with waste fuels because ofhigh fines and moisture content. The crushed fuel (6-12 mm x0) is stored in the silo, usually located in front of the boiler asshown in Fig. 6. Fuel is fed to the boiler via down spout fromsilo discharge to feeder and a series of feeders and gravity feedchutes. The fuel chute will have at least a 65 degree angle fromhorizontal. Primary air is used to sweep the fuel into the furnace and as seal air to the feeders. The number of feed points isset to achieve even fuel distribution in the furnace.The limestone handling and feeding system is relativelysimple compared to the fuel feed system. Limestone is fed either pneumatically or mechanically into the CFB boiler. Thepneumatic system feeds the limestone directly into the furnacethrough furnace openings in the front and rear walls. In themechanical system, the limestone is fed into the discharge endof the fuel feeders via rotary feeders. The limestone falls bygravity down the fuel feed chute with the fuel into the furnace,and is a function of fuel velocity and required emissions.CFB Technology ComparisonVirtually all major boiler manufacturers are involved inCFB technology. Two distinct types of solids separation systems are used. One type is cyclone–based, which provides singlestage solids collection systems, and the second type is impactseparator-based, which provides a two-stage solids separationsystem. A comparison of B&W IR-CFB technology features withthose of other major commercial CFB technologies is given inTable 4.Advantages of the B&W IR-CFB Boiler technology*Boiler is compact with primary U-Beam separators andprovides internal solids recycle.* Boiler has a smaller foot print (up to 20 to 30% less building volume compared to a hot cyclone-based CFB boiler)* Boiler design is especially suitable for retrofitting of olderPC-fired boilers within the existing support steel.* Two-stage solids separation efficiency (>99.7%) provideshigher carbon efficiencies and better limestone utilization through higher solids residence time.* Wide turndown ratio (4:1) without auxiliary fuel is possible due to the selection of furnace velocity and control-lable solids recycle.* Less refractory in the boiler allows for quicker startupand lower maintenance costs.Economics of CFB TechnologyCFB technology can burn a wide range of low cost solidfuels and competes well with oil/gas fired plants. The decision-makers often ask, ―What are capital and operating costs andbenefits of a CFB boiler?‖ The experience in Europe and NorthAmerica suggests that for a sulfur fuel (>0.5%S) and less than150 MW, a CFB boiler has 8-15 percent lower capital costs aswell as 5-10% lower operating costs than a PC-fired boiler because of the FGD system. In general, CFB-based power plantsprovide low emissions control costs and low O&M costs, whichlead to lower life cycle costs. In the end, owner profit marginincreases and payback period improves as shown in Table 5.Costs not included in Table 5 are items such as land, projectdevelopment, permitting, escalation, taxes and owner’s costs,since these costs are common for both PC and CFB-based powerplants.Reliability of CFB TechnologyCFB boiler design is simple and proven, compared to othertechnologies. Experience indicates that operating and maintenance costs are relatively lower than PC-fired boilers becauseof the ability to burn lower rank fuels, thus reducing fuel costescalation uncertainty. Since maintenance areas are very minimal in the CFB boiler, the availability of the boiler is relativelyhigher. The CFB design allows emissions reduction without significant capital cost, since SO2 and NO x removal are inherentwithin the combustion process.ConculusionEven though a number of competing technologies areavailable in the market for steam and electric power generation, CFB is an excellent choice due to its fuel flexibility, widerturndown without support oil/gas, superior environmental performance, lower operating and maintenance costs, and safe, reliable and simple boiler operation. The B&W IR-CFB boilerdesign offers compact, superior performance due to two-stagesolids separation, and is cost effective for multiple fuel firingin both PC retrofit and greenfield applications.2；译文（1）燃煤循环流化床锅炉运行情况燃煤发电行业继续搜寻成本效益的方式,以增加发电量,同时达到日益严格的排放标准. 过去几年,流化床燃烧已成为一种可行的选择. 一个公司有重大领域的经验,工业及电站锅炉设计开发了紧凑型大气内部循环流化床(红外CFB )锅炉投入商业应用.Babcock & Wilcox的红外流化床装置, 最近在南伊利诺伊大学和印度的一个工业设施中，在一份由S.kavidass和米哈伊尔Maryamchik的Babcock &Wilcox (巴伯顿,俄亥俄州) , C.SIU(代尔,伊利诺州) ,和A的[27]卡诺里亚&化学工业有限公司( renukoot ,印度) 被报道 . 这份文件题为"巴威的红外循环流化床燃煤锅炉的操作经验" ,并提交于15年度国际匹兹堡煤炭会议于9月14-18 , 1998年在匹兹堡,宾夕法尼亚州.红外型循环流化床锅炉设计在循环流化床锅炉，煤粉被引入炉膛内的床上，其中包含或惰性物质（如砂或粉碎石灰石）或白云石。

A Large-Capacity Pressurized-Fluidized-Bed-Combustion-Boiler Combined-Cycle Power PlantOVERVIEW: To improve the thermal efficiency and environmental characteristics of coal-fired power-generation systems, The Chugoku Electric Power Co., Inc. and the Hitachi Group developed the first commercial 250-MW PFBC (pressurized fluidized bed combustion) combined-cycle powerplant in Osaki. The Osaki PFBC plant was commissioned, and its commercial operation began on Nov. 30, 2000. We will describe the main features of the equipment and several trial-operation results of the Osaki PFBC plant. The plant has a combined-cycle arrangement with the gas turbine and steam turbine producing an output of approximately 15 and 85%, respectively, of the total electricity. It also has a pressurized-fluidized-bed-combustion boiler,which generates steam to drive the steam turbine. The gas from the boiler is directed to a two-stage multi-cyclone, which drives the gas turbine. The boiler consists of two vessels with two furnaces.INTRODUCTIONAS global environmental problems are becoming animportant matter of international concern, the demandfor coal-fired thermal power stations that can reducethe CO2 emissions through the improvement of their thermal efficiency and minimize the emissions of SOx, NOx, soot, and dust from the boilers is increasing.This can be achieved by the development of a new power-generation system. Recently, the Hitachi Group supplied the Osaki Power Station of The Chugoku Electric Power Co.,Inc., with a 250-MW pressurized-fluidized-bedcombustion (PFBC)-boiler combined-cycle powerFig. 1—250-MW Pressurized-Fluidized-Bed-Combustion-Boiler Combined-Cycle Power Plant Delivered to Osaki PowerStation of The Chugoku Electric Power Co., Inc. (Series 1, Unit1-1).plant as Unit 1-1. This is a compact, efficient, and environmentally friendly coal-fired thermal-power plant. To develop this power plant, from its design and fabrication to installation and test operation, the Hitachi Group led comprehensive discussions with The Chugoku Electric Power Co., Inc., that included a joint study at the 4-MW test plant of the Thermal Power Generation Technical Center of the company. Following the completion of the installation that took some 40 months after the start of theconstruction work in November 1995, the overall test operation began in March, 1999. The plant was put into commercial operation in November, 2000.This article describes the 250-MW PFBC powerplant project and the results of the test operation of the plant 1,2).Fig. 1 sh ows a bird’s-eye view of The Chugoku Electric’s Osaki Power Station that houses the main equipment fabricated by the Hitachi Group. Figs. 2 and 3 show the main equipment.The boiler is a twin-furnace type. The steam turbine and gas turbine are laid out in a T shape.250-MW PFBC PLANT EQUIPMENT General System Configuration The general system configuration of the plant is shown in Fig. 4, and the principal specifications of the plant are listed in Table 1. Unit 1-1 that was delivered to The Chugoku Electric’s Osaki Power Station is a combined-cyclepower-generation system, in which the steam turbine is driven by steam generated by a PFBC boiler housed in a pressure vessel and the gas turbine is driven by gas from which the dust is removed by two series of 12 two-stage cyclones (a multi-cyclone housed in an exclusive pressure vessel). By using limestone as the boiler-bed material, we could desulfurize the furnace gas and significantly reduce the SOx emissions. The boiler is a twin-furnace, twin-tower type, and the gas turbine is a single-shaft type. The fuel coal is fed intothe boiler in the form of coal-water paste (CWP), a mixture of coal, limestone that serves as the desulfurizing agent and bed material, and water.The Main Equipment BoilerThe fuel is burned under an in-furnace pressure of approximately 1 MPa, whereby the hearth load is increased and the required furnace cross-section area is reduced (i.e., the furnace is compact). Appropriate steps were taken to ensure uniform flow, stability, temperature uniformity, and so on, of the fluidized bed. They include the use of inclined front- and rear-end walls, a uniform arrangement of the heat-exchanger tubes in the furnace, and the installation of many airdistribution nozzles in the hearth at equal intervals3). In the fuel-supply system, a mixture of fuel coal, limestone, and water (CWP), prepared outside the pressure vessel, is fed into the fluidized-bedcombustion furnace inside the pressure vessel. This system reduced the number of through pipes in the pressure vessel and improved the safety of the furnace. To enable good controllability of the boiler operation and easy transportation and installation of the boiler (the project site is located on an island in the Inland Sea of Seto), we developed a twin-furnace, twin-tower boiler (“W.B.”). This boiler was shipped in the formof modules from the Kure Works of Babcock-Hitachi K.K.Fig. 3—Steam Turbine (Bottom) and Gas Turbine (Top) of the Power Station.The fluidized-bed temperature is 865°C. The bedheight varies from 2.5 to 4.0 m to enable changing theeffective area of the heat-exchanger tubes laid out inthe bed and adjusting the amount of steam generatedby the boiler. The flue gas from the boiler is first cleaned from soot and dust by two-stage cyclones until the soot and dust concentration drops below 1,000 mg/ m3N and is then fed to the gas turbine.Sulfur oxides (SOx) in the furnace gas aredesulfurized by the limestone in the furnace and thelimestone fed into the furnace together with coal. The formation of nitrogen oxides (NOx) is prevented by low-temperature combustion and the emissions of NOx are reduced by the use of flue-gas denitrification equipment (catalytic and non-catalytic denitrification). Thus, the boiler is environmentally friendly.Gas turbine and steam turbineThe gas turbine is similar to the one installed at The Chugoku Electric’s Yanai Power Station but was modified for PFBC. To ensure that the turbine blades can withstand the coal-ash-bearing hot gas (approximately 840°C) from the boiler, the thickness of both the rotating blades and stationary blades was increased and the blade coating characteristics were improved. A combination of an exclusive motor and exclusive combustors is used to start the gas turbine. The amount of air fed into the boiler is controlled by a compressor inlet pressure-reducing valve installed in the gas-turbine-compressor air-inlet duct and a guide vane installed at the compressor air inlet.The steam turbine uses a heat cycle whereby the gas-turbine waste heat is recovered by the steamturbine condensate and feed-water system. In addition, to improve the plant thermal efficiency, a TCDF-33.5 steam turbine that can be operated under large loads wasadopted.Fig. 4—General System Configuration of the 250-MW PFBC Power Plant. Fuel, compressed air, and water are fed into the twin-furnace, twin-tower boiler. As the fuel burns in the boiler, steam and high-pressure gas are generated.TABLE 1. Principal Specifications of the 250-MW PFBC Power Plant This plant uses a “two stage cyclone + bag filter” system, not a conventional ceramic-filter system, to remove soot and dust from the boiler flue gas.Fig. 5—Central Control Room. The central control room contains an automation panel, a large screen, and auxiliary panels for independent operation(1) The control system is composed of a central monitor panel, computers, and controls. The central monitor panel consists of an automation panel equipped with five CRT displays, a large screen, and auxiliary panels for independent operation. Centralized operations, including the operation of electrical equipment, are all performed by means of the CRT displays. To enable handling huge volumes of monitor information, we used a high-function, highperformanceCRT processor (see Fig. 5).(2)In automating the control operations, the control functions were distributed between the control computers and control devices for optimum results All plant operations, from the start of the seawater system to the operation of the plant under a full load to the shut-down of the plant, were made sequential on a system-by-system basis to implement a fullyautomated plant based on control computers. For routine operations, we adopted a remote, sequential control to minimize labor costs in plant operation.(3) For the main control equipment, such as the boiler control, turbine control, and sequence control, the HIACS-7000 system was used to configure horizontally-distributed control systems. The integration of controls by using a large-capacity, highperformance controller and the use of a high-speed data-transmission network (100 Mbit/s) enabled implementing a CRT-based operation of the entire plant and establishing a good human interface.(4) Instead of a conventional wired interlock of auxiliary devices, a programmable control module (PCM) and a remote process-input-and-output (PI/O) device were used. This significantly reduced the number of auxiliary relay panels and converter panels and enabled flexible response to field modifications. Because the remote PI/O devices were installed in thefield, the cable work could be reduced dramatically.TEST-OPERATION RESULTSPlant Performance To evaluate the plant performance during the hours of a season in which the atmospheric temperature at the site of the plant is almost the same as the atmospheric temperature for which the plant was designed, in May 2000, the plant was subjected to test operation under a rated output of 250 MW. We found that every piece of equipment of the plant met its planned output and efficiency. All the functions of the PFBC boiler worked as planned, including the infurnace desulfurization, non-catalytic denitrification (injection of an ammonia gas into the hot gas pipe at the furnace outlet), dust removal by two series of twostage multicyclones, etc. The planned figures for the emissions of NOx, SOx, and soot and dust were met completely (see Table 2).Plant Starting/Stopping The characteristics of the process of starting the plant in a cold mode, from the start of the gas turbine to the attainment of a rated load, are shown in Fig. 6.TABLE 2. Plant Performance (Planned Figures vs. Measured Results) Both the environmental-performance and thermal-efficiency results met the planned figurescompletely.Fig. 6— Measured Cold-Start Characteristics (Nov. 9-10, 2000). After the gas turbine is started, fuel is fed into the boiler to generate steam, which drives the steamturbine.Fig. 7— Plant Behavior at Load Change (May 11, 2000).One of the characteristics of the process of starting a PFBC plant is that once the plant equipment is synchronized with the electric power system, the gas turbine generator is operated as a synchronous motor by the electric power from the system, whereby the gas-turbine compressor is driven to feed the combustion air into the furnace. As the fuel is fed intothe furnace and the temperature and height of the fluidized bed increase, the boiler generates steam and hot gas from the burning coal. In this process of a load increase, the gas turbine generator switches from the synchronous motor to a synchronous generator.Change in Plant LoadIn a PFBC boiler, both the bed temperature and the main-steam temperature change according to the change in the fuel-feed rate. Therefore, to protect the equipment, it is necessary to maintain both temperatures within a certain range on a stable basis. In the present boiler, the bed height and the fuelfeed rate are adjusted to enable stable control of the bed and main-steam temperatures. When the bed height is changed, the area of contact between the heat exchanger and fluidized bed in the furnace changes, causing the quantity of the heat transferred from the furnace to the steam to change. As a result, both the bed temperature and the steam temperature change. Therefore, a PFBC plant needs a control system capable of keeping the bed and main-steam temperatures within the prescribed limits by controlling the fuel-feed rate and the bed height simultaneously. The present PFBC plant uses a system that controls the main steam temperature by the fuelfeed rate, which enables comparatively good plant operability and bed-temperature control with a comparatively large tolerance to the bed height. The measured characteristics of the plant behavior during a load change are shown in Fig. 7. CONCLUSIONSWe described the equipment of 250-MW Series 1,Unit 1-1 that was delivered to Osaki Power Station of The Chugoku Electric Power Co., Inc., as well as the results of the test operation. The PFBC plant went through the test operation smoothly, satisfactorily, demonstrating the planned performance. We intend to test the reliability of the PFBCequipment on the basis of operation results, which will be accumulated in the future. In concluding this paper, we would like to thank all the people of The Chugoku Electric Power Co., Inc., for their generous and extensive guidance and cooperation in all phases of the present PFBC project for Osaki Power Station, from plant planning to plant construction and test operation.REFERENCES(1)K. Horiuchi et al., “Test Operation of Osaki PFBC System,” The 7th National Symposium on Power and Energy Systems (Oct. 2000) in Japanese.(2) H. Komatsu et al., “Completion of a Large-Capacity Pressurized Fluidized Bed Combustion Boiler Combined Cycle Power Plant,” Hitachi Hyoron 83, pp.41-44 (Feb. 2001) inJapanese.(3) O. Ito et al., “Direct Measurement of Particle Motion on a Large-Scale FBC Boiler Model,” Proceedings of the 15th International Conference on Fluidized Bed Combustion, FBC99-0023 (May 1999).ABOUT THE AUTHORSHideaki Komatsu Joined Hitachi, Ltd. in 1974, and now works at the Thermal Power Plant Engineering Department of the Power & Industrial Systems. He is currently engagedin the development of thermal power plant systems. Mr. Komatsu is a member of Japan Society ofMechanical Engineers.Masakatsu Maeda Joined Babcock-Hitachi K.K. in 1965, and now works at the Thermal Power Division. He is currently engaged in the development of thermal power boilers.Mr. .Masaru Muramatsu Joined Hitachi, Ltd. in 1965 and now works atthe Power Plant Control Systems Engineering Department of the Power & Industrial Systems. He is currently engaged in the development of thermal power plant control systems.。