Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.
This standard is developed in accordance with the rules given in GB/T 1.1-2009 Directives for standardization - Part 1: Structure and drafting of standards.
Attention is drawn to the possibility that some of the elements of this standard may be the subject of patent rights. The issuing authority of this standard shall not be held responsible for identifying any or all such patent rights.
This standard replaces DL/T 468-2004 Guide on type selection and application for power boiler fans. In addition to editorial changes, the following main technical changes have been made with respect to DL/T 468-2004:
——The definitions of forced draft fan and induced draft fan in clause 3 have been modified;
——The definition of stall safety factor of axial flow fan has been added in clause 3;
——The definitions of base flow, base pressure and test block have been added in clause 3;
——The title of clause 4 has been changed as design requirements of fan;
——The relevant contents on the requirements of fan manufacturing in clause 4 have been deleted;
——The title of clause 5 has been changed as type selection of fans;
——The requirements for original data ought to be provided for fan selection have been given in clause 5;
——The requirements on the selection of fan rotating speed in clause 5 have been modified;
——The requirements on selection of number of fans in clause 5 have been modified;
——The requirements on fan adjustment method in clause 5 have been modified;
——The requirements on stall safety factor of axial flow fan in clause have been modified;
——The clause 6 "Installation of fan" in the original standard has been deleted;
——The serial number of clause 7 of the original standard has been revised to 6, and the serial numbers of subsequent clauses and subclauses has been revised accordingly;
——The requirements on operating parameter control in clause 6 “Fan operation” have been modified.
This standard was proposed by the China Electricity Council.
This standard is under the jurisdiction of DL/TC 08 Technical Committee on Power Station Boiler of Standardization Administration of Power Industry.
The previous editions of this standard are as follows:
——DL/T 468-1992;
——DL/T 468-2004.
Any comments or suggestions during the implementation of this standard may be fed back to the Standardization Center of the China Electricity Council (No.1, 2nd Lane, Baiguang Road, Beijing, 100761, China).
Guide to selection and application of boiler fans for power plants
1 Scope
This standard specifies the basic requirements for the selection and application of boiler fans for power plants as well as for arrangement and design of inlet and outlet pipelines of fans.
This standard is applicable to forced draft fan, induced draft fan, primary fan, exhauster (pulverized coal fan), flue-gas recirculating fan, booster fan of flue gas desulfurization device and seal air fan for coal mill. Reference may be made to this standard for other small fans for boilers, such as ignition fan, cooling fan and dilution fan of SCR denitration system.
This standard is not applicable to oxidation fans of desulfurization systems and high-pressure fluidization fans of circulating fluidized bed boilers.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 1236 Industrial fans - Performance testing using standardized airways
GB/T 2888 Methods of noise measurement for fans blowers compressors and roots blowers
GB/T 3235 Basic types sizes parameters and characteristics curve of fans
GB/T 3947 Acoustical terminology
GB/T 10178 Industrial fans - Performance testing in situ
GB/T 17774 Industrial fans - Dimensions
GB/T 19075 Industrial fans - Vocabulary and definitions of categories
GB 50660 Code for design of fossil fired power plant
DL/T 469 Fans performance testing in situ for power boiler
DL/T 5121 Technical code for design of thermal power plant air & flue gas ducts/ raw coal & pulverized coal piping
DL/T 5145 Technical code for design and calculations of coal pulverizing system of fossil-fired power plant
DL 5190.2 Technical specification for thermal power erection and construction - Part 2: boiler unit
JB/T 4358 Centrifugal fan for boiler of power station
JB/T 4362 Power station axial fans
JB/T 6891 Technical specification for silencer of fan
JB/T 8689 Fan vibration detection and its limited value
JB/T 8690 Industrial fans noise limited value
JB/T 8822 High temperature centrifugal fan - Specification
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
forced draft fan; FDF
fan that supplies air needed for boiler fuel combustion and is arranged in front of the boiler air preheater, which sends the air sucked from the atmosphere to the air preheater to heat it to the design temperature, then, for direct-fired pulverizing system, sends the air directly into the boiler furnace through the burner as the secondary air of the boiler and, for the middle storage pulverizing system, sends one part of the air directly into the boiler furnace through the burner as the secondary air of the boiler and the other part of the air into pulverized coal preparation system as desiccant or into furnace as primary air conveying the pulverized coal through burner (exhaust gas pulverized coal feeding system) or into furnace as tertiary air through the burner (hot air pulverized coal feeding system); large boilers adopting medium speed coal mills or double-inlet and double-outlet low speed coal mill positive pressure direct-fired pulverizing system are all equipped with high-pressure cold primary fans which either draw air from the outlet of the forced draft fan which supplies the total air volume required by the boiler or draw air from the atmosphere, in which case the forced draft fan only supplies the secondary air to the boiler, which is also called the secondary air fan.
3.2
induced draft fan; IDF
fan installed behind the boiler dust remover, sucking out the boiler combustion products (flue gas) from the boiler tail and sending to the booster fan of the desulfurization system after passing through the denitration system and dust removal system and, after the flue gas pressure is raised by the booster fan, discharging the flue gas into the atmosphere from the chimney through desulfurization system, also known as the suction fan, which shall overcome the resistance of the whole flue gas system from boiler furnace to chimney outlet if there is no booster fan, in which case it is commonly known as 2-in-1 induced draft fan
3.3
primary fan; PF
fan that supplies primary air needed for boiler fuel combustion, which is classified by its installation position in the system into cold primary fan and hot primary fan
3.4
cold primary fan
primary fan installed in front of the boiler air preheater and sending the air sucked from the atmosphere or from the outlet cold air duct of the forced draft fan into pulverizing system after being heated by the air preheater
3.5
hot primary fan
primary fan which is installed behind the boiler air preheater and sends the air heated by the boiler air preheater to direct-fired pulverizing system or sends only the pulverized coal to the boiler
3.6
exhauster
fan for conveying desiccant and pulverized coal in pulverized coal preparation system, which is mainly used in the middle storage pulverizing system and installed behind the fine powder separator, also known as pulverized coal fan
3.7
flue-gas recirculating fan
fan sucking out part of the flue gas from the backside of the economizer and front of the air preheater, the lower part of furnace, the backside of the electrical precipitator, the outlet of induced draft fan, etc., and delivering to the boiler cold ash hopper or the upper part of furnace to adjust the boiler steam temperature or delivering to the coal mill inlet to adjust the temperature or oxygen content
3.8
flue gas desulfurization booster fan
fan set behind the induced draft fan to overcome the resistance of the flue gas desulfurization system
3.9
seal air fan
fan for supplying sealing air for medium speed coal mill, double-inlet and double-outlet low speed coal mill and coal feeder, which may suck air directly from the atmosphere, and may also suck air from the outlet pipeline of forced draft fan or primary fan
3.10
inlet plane and inlet area of fan
A1
fan inlet plane referring to the surface bounded by the upstream extremity of the air moving device, and generally, fan inlet area referring to the total through-flow area of the inlet (flange) plane of the enclosure (or the inlet box in the case of fans with inlet box)
3.11
outlet plane and outlet area of fan
A2
fan outlet plane referring to the surface bounded by the downstream extremity of the air moving device, and generally, fan outlet area referring to the total area of the plane of the enclosure outlet (flange)
3.12
stall safety factor of axial flow fans
vector indicating the stall margin of axial flow fan in this standard, which is expressed by k (see 5.4.4 of this standard)
3.13
fan system
system consisting of fan, equipment as well as a series of air duct, pipe, bend and branch pipe on the conveying path for conveying air or gas from one or more places to another one or more places
3.14
system characteristic curves
diagram for resistance versus volumetric flow characteristics of a system
3.15
system effect
influence of system layout on fan performance which is affected by the inlet and outlet connection pipes which, if connected improperly, together with uneven airflow at the inlet and vortex at the inlet of the fan, will change the aerodynamic characteristics of the fan and reduce the performance of the fan
3.16
system effect loss
reduction of fan pressure caused by system effect
3.17
base flow
fan flow required for operation at the boiler maximum continuous rating calculated according to the design coal type
3.18
base pressure
total resistance of fan system when operating at the boiler maximum continuous rating calculated according to the design coal type
3.19
test block
maximum continuous operation condition of the fan required for type selection
3.20
specific A sound level; LSA
A sound level at unit flow rate and unit fan pressure, which shall be calculated using Equation (1):
(1)
where,
LSA——the specific A sound level, dB(A);
LA——the A sound level, dB (A);
qV——the volumetric flow rate, m3/min;
pF——the fan pressure, Pa.
4 Design requirements of fans
4.1 General requirements
4.1.1 The design of fans shall meet the requirements of GB/T 3235 and GB/T 17774.
4.1.2 The design and manufacture of centrifugal fans shall meet those specified in JB/T 4358.
4.1.3 The design and manufacture of axial flow fans shall meet those specified in JB/T 4362.
4.1.4 The natural vibration frequency of the fan impeller (or blade) shall not be the same as the rotating speed frequency of the impeller and the frequency multiplication less than 10 times of it, or other dangerous frequencies, such as the blade passing frequency, i.e., the product of the rotating speed (for fans with rotating speed regulation, it refers to all the rotating speeds within the regulation range) and the number of blades (includes rotor blades and front and rear adjustable or guide blades for impellers), and high amplitude air motion frequency.
4.1.5 For fans with variable speed adjustment, calculations on torsional vibration of shafting shall be conducted to prevent it from occurring.
4.1.6 The fan shall be equipped with necessary automatic alarm and protection devices (such as those for bearing temperature, fuel cut-off, vibration, and stall flutter of axial flow fan).
4.1.7 Fans with air intake from the atmosphere (such as forced draft fans and primary fans) shall be equipped with an air inlet silencer that is designed and manufactured in accordance with JB/T 6891.
4.2 Design requirements
4.2.1 For hot primary fan, the design inlet air temperature shall be 250℃, the maximum allowable inlet air temperature shall not exceed 400℃ and the airborne dust concentration shall not exceed 100mg/m3. The design of it shall comply with those specified in JB/T 8822.
4.2.2 The flue gas system upstream of the induced draft fan is equipped with a low-temperature economizer system, and the inlet temperature of the induced draft fan is around 90℃, at which the flue gas is corrosive, so reliable anti-corrosion measures shall be taken in the flow path of the fan.
4.2.3 The exhauster (pulverized coal fan) is designed to convey air containing pulverized coal. The pulverized coal content shall not be greater than 80g/m3 for the exhaust gas from middle storage pulverizing system of low speed coal mill, and it shall be 300g/m3~800g/m3 for negative-pressure direct-fired pulverizing system. The design inlet gas temperature and the maximum allowable inlet gas temperature shall be 70℃ and 150℃, respectively. The enclosure and impeller shall be protected from wear according to the wear characteristics of the coal (see DL/T 5145 for the wear indexes), and the service life of the impeller shall not be less than 8,000h.
4.2.4 The flue-gas recirculating fan is designed to convey hot flue gas with an ash content no greater than 20g/m3 and a temperature no higher than 400℃. The volute and impeller shall be properly protected from wear. The bearings shall be equipped with special heat insulation and cooling devices, and their service life shall not be less than 8,000h. Flue-gas recirculating fan without speed adjusting device shall be equipped with a turning device.
4.2.5 Noise countermeasures shall be taken in the design of seal air fan. Seal air fans with direct air intake from the atmosphere shall be equipped with inlet filters and inlet and outlet silencers.
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Design requirements of fans
5 Type selection of fans
6 Fan operation
7 Fan noise
8 Test and acceptance of fan
9 Fan system design
Annex A (Informative) Necessary information on selection of fan
Annex B (Informative) Necessary information for evaluation of fan design
Annex C (Informative) Calculation of standard density of humid air
电站锅炉风机选型和使用导则
1 范围
本标准规定了电站锅炉风机的选型、使用及风机进出口管道布置设计的基本要求。
本标准适用于电站锅炉的送风机、引风机、一次风机、排粉风机(煤粉风机)、烟气再循环风机、烟气脱硫装置的增压风机和磨煤机用的密封风机。其他供锅炉用的小型风机如点火风机、冷却风机、SCR脱硝系统的稀释风机等可参照使用。
本标准不适用于脱硫系统的氧化风机和循环流化床锅炉的高压流化风机。
2 规范性引用文件
下列文件对于本文件的应用是必不可少的。凡是注日期的引用文件，仅注日期的版本适用于本文件。凡是不注日期的引用文件，其最新版本(包括所有的修改单)适用于本文件。
GB／T 1236 工业通风机 用标准化风道进行性能试验
GB／T 2888 风机和罗茨鼓风机噪声测量方法
GB／T 3235 通风机基本型式、尺寸参数及性能曲线
GB／T 3947 声学名词术语
GB／T 10178 工业通风机 现场性能试验
GB／T 17774 工业通风机 尺寸
GB／T 19075 工业通风机 词汇及种类定义
GB 50660 大中型火力发电厂设计规范
DL／T 469 电站锅炉风机现场性能试验
DL／T5121 火力发电厂烟风煤粉管道设计技术规程
DL／T5145 火力发电厂制粉系统设计计算技术规定
DL5190.2 电力建设施工技术规范 第2部分：锅炉机组
JB／T 4358 电站锅炉离心式通风机
JB／T 4362 电站轴流式通风机
JB／T 6891 风机用消声器技术条件
JB／T 8689 通风机振动检测及其限值
JB／T 8690 工业通风机 噪声限值
JB／T 8822 高温离心通风机技术条件
3 术语和定义
下列术语和定义适用于本文件。
3.1
送风机forced draft fan；FDF
供给锅炉燃料燃烧所需空气的风机。布置在锅炉空气预热器之前。将从大气中吸入的空气送入空气预热器，加热到设计温度后，对于直吹式制粉系统，作为锅炉的二次风，直接经燃烧器送入锅炉炉膛。对于中间仓储式制粉系统，则一部分作为锅炉的二次风，直接经燃烧器送入锅炉炉膛；另一部分进入煤粉制备系统作为干燥剂，或作为一次风输送煤粉经燃烧器送入炉膛(乏气送粉系统)，或作为三次风经燃烧器送入炉膛(热风送粉系统)。大型锅炉采用中速磨煤机或双进双出钢球磨煤机正压直吹式制粉系统，均配有高压冷一次风机。一次风机有从送风机出口吸取空气的，则送风机供给锅炉所需的总风量；也有专门从大气吸入空气的，此时送风机只供给锅炉的二次风，亦称二次风机。
3.2
引风机 induced draft fan；IDF
安装在锅炉除尘器之后，将锅炉燃烧产物(烟气)从锅炉尾部吸出并经脱硝系统、除尘系统后送入脱硫系统的增压风机，提升压力后再经脱硫系统由烟囱排入大气的风机，又称吸风机。如不设增压风机，则从锅炉炉膛到烟囱出口整个烟气系统的阻力均由引风机克服(俗称二合一引风机)。
3.3
一次风机 primary fan：PF
供给锅炉燃料燃烧所需一次空气的风机。按其在系统中的安装位置，有冷一次风机和热一次风机之分。
3.4
冷一次风机 cold primary fan
安装在锅炉空气预热器之前，将从大气或从送风机出口冷风道抽吸的空气经空气预热器加热后输送至制粉系统的一次风机。
3.5
热一次风机 hot primary fan
安装在锅炉空气预热器之后，输送经过锅炉空气预热器加热后的热空气至直吹式制粉系统或仅输送煤粉至锅炉的一次风机。
3.6
排粉风机 exhauster
煤粉制备系统中用以输送干燥剂和煤粉的风机。主要用于中间储仓式制粉系统中，安装在细粉分离器之后。也称煤粉风机。
3.7
烟气再循环风机 flue-gas recirculating fan
把一部分烟气从省煤器后空气预热器前、炉膛下部、电除尘器后、引风机出口等处抽出，并输送至锅炉冷灰斗或炉膛上部，用以调节锅炉蒸汽温度；或送至磨煤机入口用以调节温度或含氧量的风机。
3.8
烟气脱硫增压风机 flue gas desulfurization booster fan
在引风机后设置的用以克服烟气脱硫系统阻力的风机。
3.9
密封风机 seal air fan
供给中速磨煤机、双进双出钢球磨煤机和给煤机等装置密封用空气的风机。密封风机可直接从大气吸入空气，也可从送风机或一次风机出口管道内吸取空气。
3.10
风机进口平面和进口面积 inlet plane and inlet area of fan
A1
取空气输送装置上游末端的界面为风机进口平面。通常，取机壳(带进气箱的风机取进气箱)进口(法兰)平面的通流总面积作为风机进口面积。
3.11
风机出口平面和出口面积 outlet plane and outlet area of fan
A2
取空气输送装置下游段始端的界面为风机出口平面。通常，取机壳出口(法兰)平面的总面积作为风机出口面积。
3.12
轴流式风机失速安全系数 stall safety factor of axial flow fans
本标准表示轴流式风机失速裕度的量，用k表示(见本标准5.4.4)。
3.13
风机系统 fan system
为从一处或多处向另一处或多处输送空气或气体而由风机和输送路径上的各设备及一系列风筒、管路、弯管和支管所组成的系统。
3.14
系统特性曲线 system characteristic curves
某个系统的阻力对容积流量特性的图解。
3.15
系统效应 system effect
系统布置对风机性能的影响。风机的性能受其进、出口连接管道的影响。如果连接不当、进口气流不均匀，以及风机进口处存在涡流，则将改变风机的空气动力特性，降低风机的性能。
3.16
系统效应损失 system effect loss
由系统效应引起的风机压力的降低。
3.17
基本风量 base flow
按设计煤种计算的锅炉最大连续蒸发量运行所需的风机流量。
3.18
基本压力 base pressure
按设计煤种计算的锅炉最大连续蒸发量运行时的风机系统总阻力。
3.19
选型工况(TB工况) test block
选型要求风机应达到的最大连续运行工况。
3.20
比A声级 specific A sound level；LSA
单位流量、单位风机压力时的A声级。比A声级按式(1)计算：
(1)
式中：
LSA——比A声级，dB(A)；
LA——A声级，dB(A)；
qV——体积流量，m3／min；
pF——风机压力，Pa。
4 风机的设计要求
4.1 总体要求
4.1.1 风机的设计应符合GB／T 3235及GB／T 17774的要求。
4.1.2 离心式风机的设计制造应符合JB／T 4358的规定。
4.1.3 轴流式风机的设计制造应符合JB／T 4362的规定。
4.1.4 风机叶轮(或叶片)的自振频率应避开叶轮的转速频率及其10倍以下倍频和其他危险频率，如叶片通过频率即转速(采用转速调节的风机包括转速调节范围内的所有转速)与叶片数(包括转子叶片和叶轮前后调节或导向叶片)的乘积、高幅值的气流脉动频率等。
4.1.5 采用变速调节的风机，应进行轴系扭转振动计算，防止轴系发生扭转振动。
4.1.6 风机应设有必要的自动报警和保护装置(如轴承温度、断油、振动和轴流式风机的失速喘振等)。
4.1.7 自大气吸气的风机(如送风机、一次风机)应配备进口消声器，消声器的设计和制造应符合JB／T 6891的规定。
4.2 设计要求
4.2.1 热一次风机的设计进口空气温度为250℃，允许最高进口空气温度不超过400℃，空气的含尘浓度不超过100mg／m3。其设计应符合JB／T 8822的规定。
4.2.2 引风机上游烟气系统配备有低温省煤器的系统，引风机入口温度在90℃左右，具有腐蚀性，在风机的通流部分应采取可靠的防腐措施。
4.2.3 排粉风机(煤粉风机)设计要求输送的介质是含煤粉的空气。其含煤粉量，对于钢球磨煤机中间储仓式制粉系统的乏气不大于80g／m3，对于负压直吹式制粉系统为300g／m3～800g／m3。其设计进口气体温度为70℃，允许最高进口气体温度为150℃。机壳和叶轮应根据煤的磨损特性(磨损指数的高低见DL／T 5145)采取防磨损措施，其叶轮的使用寿命不少于8000h。
4.2.4 烟气再循环风机设计要求输送的介质为含灰量不大于20g／m3、温度不高于400℃的热烟气。其蜗壳和叶轮应采取适当的防磨损措施；轴承需设专门的隔热和冷却装置，其使用寿命不得少于8000h。未配置调速装置的烟气再循环机应设置盘车装置。
4.2.5 密封风机的设计应采取消声措施。对从大气直接吸气的密封风机，应配备进口过滤器和进、出口消声器。
5 风机的选型
5.1 选择风机应提供的原始数据
选择风机应提供的原始数据至少包括：
a) 当地大气条件：
1) 大气压力；
2) 干、湿空气温度；
3) 空气相对湿度。
b) 锅炉热力计算和空气动力计算结果。
c) 锅炉各典型工况下的风机参数：
1) 流量(风量、烟气量)；
2) 风机进口侧系统总阻力(即风机进口全压)和与之对应的风机进口风道截面动压；
3) 风机出口侧系统总阻力(即风机出口全压)；
4) 风(烟)系统总阻力(即风机压力，以往称风机全压)；
5) 介质温度；
6) 介质标准密度(空气介质为当地湿空气的标准密度；烟气介质为风机进口湿烟气的标准密度)。
注：各典型工况包括：
——选型工况(TB)；
——BMCR工况；
——BRL工况；
——THA工况；
——75％THA工况；
——50％THA工况；
——不投油最低稳燃工况。
d) 机组在不同负荷下年运行小时数。
5.2 风机选型参数的确定
5.2.1 基本风量按照以下要求确定：
a) 对于新建锅炉的风机，基本风量按GB 50660的相关规定确定。
b) 对于改造已投运的风机，其基本风量需由现场试验确定。试验工况不少于三个(在机组高、中、低三个负荷下进行)，并将试验结果换算至锅炉最大连续蒸发量(BMCR)工况下的流量。
5.2.2 基本风压按照以下要求确定：
a) 对于新建锅炉的风机，其基本风压按GB 50660的相关规定进行计算，计算所得的风机系统阻力宜参考同类型机组的实际运行值确定是否需进行调整。
b) 对于改造已投运的风机，其基本风压由现场试验确定(风压试验应与流量试验同时进行，并通过DCS对系统内各主要设备及有关管道的阻力进行采集)。必要时，进行测量和／或通过SIS采集近一年内机组满负荷时风机进、出口压力值予以核对。应同时考虑风机对应系统(包括系统中的其他设备)的改造引起的阻力变化，并将换算至锅炉最大连续蒸发量(BMCR)下的系统总阻力确定为风机选型的基本风压。
5.2.3 风量、风压裕量按照以下要求选取：
a) 对于新建锅炉的风机，流量与压力的裕量宜根据GB 50660的相关规定选取。
b) 改造已投运的风机，风机流量、压力裕量，宜在考虑改造前试验时的气候条件与当地夏、冬两季差异、锅炉设备及烟风系统运行状况，以及机组负荷系数及煤质变化范围等因素的基础上确定：也可参照GB 50660的规定选取。
5.3 风机转速、台数及型式的选择
5.3.1 风机转速的选择，一般情况下，一次风机宜选用4极电动机(1490r／min)；送风机宜选用4极或6极电动机(1490r／min或990r／min)；引风机和脱硫增压风机的转速宜选用6极以下电动机(即最高990r／min)，对于变转速调节的引、增压风机合一的静叶调节轴流式引风机，根据参数需要可选取高于990r／min的转速，但需满足结构强度及刚度可靠的要求。
5.3.2 风机台数的选择按照以下要求进行：
a) 对50MW及以上机组，锅炉风机台数宜符合GB 50660的相关规定(送风机、引风机、冷一次风机每炉宜各设置2台：增压风机台数宜与脱硫装置台数相同：排粉机台数应与磨煤机台数相同；制粉系统密封风机每炉设置2台，一运一备)。
b) 对25MW级机组配套的锅炉应装设1台送风机和2台引风机，但燃油燃气负压锅炉应装设1台送风机和1台引风机。
c) 对12MW级及以下机组配套的锅炉应装设1台送风机和1台引风机。
d) 对50MW～600MW级机组，经技术经济论证和可靠性论证可行者，可采用每台锅炉仅设置1台送风机、1台引风机和1台一次风机。
e) 视布置条件和机组设计负荷率情况，经技术经济论证可行时，引风机也可设置3台～4台。
5.3.3 风机型式的选择按TB工况参数和选取的风机转速计算出所需风机的比转速，然后选取比转速最接近的风机型式。对于给定的参数，当可以选择几种不同型式的风机时，应根据锅炉机组的年负荷曲线、风机耗电、调节效率、设备造价、维护费用及其他因素进行综合技术经济比较来选择。不同类型风机比转速参考范围见表1。
表1 不同类型风机比转速参考范围
风机类型 比转速
单吸离心式风机 18～94
双吸离心式风机 25～120
静叶调节子午加速轴流式风机 90～120
单级静叶调节标准轴流式风机和动叶调节轴流式风机 100～200
双级静、动叶调节轴流式风机 59.5～119
5.4 风机型号的选择
5.4.1 确定风机型号应遵循的原则如下：
a) 风机型式确定后，即可按相似设计方法确定风机型号，并应使系统阻力曲线完全落在所选风机性能曲线的稳定区域内，且失速裕度足够。
b) 对于离心式风机，还应避开气流高脉动区域。
c) 对于可选不同型式或型号的风机时，在满足安全运行需要后，应根据机组负荷、利用小时数、设备费及年维护费等技术经济指标确定风机的型号。
5.4.2 离心式风机型号的选择应使选型工况点(即TB点)尽可能接近调节装置最大开度时的流量-压力曲线，并且位于风机最高效率的右侧，其效率值不应低于风机最高效率的90％。
5.4.3 轴流式风机型号的选择应在满足风机选型工况点(即TB点)能安全可靠运行的前提下，应使发电机组在经济负荷下(一般为发电机组额定出力)运行时，风机处于最高效率区运行。
5.4.4 轴流式风机选型时应确保有足够的失速裕度，关于失速裕度(失速安全系数)的定义与要求如下：
a) 失速裕度可用失速安全系数k来表示，k由各设计工况点和对应开度下(动叶调节为动叶角度，静叶调节为调节导叶角度)的失速工况点(或最大压力点)的流量、压力，并按式(2)计算得出：
(2)
式中：
p、q——各设计工况点的压力和流量：
pk、qk——各失速工况点的压力和流量。
b) 在选型设计时，各设计工况点k值宜大于1.35，即k＞1.35。
5.5 风机调节方式的选择
5.5.1 对于动叶调节轴流式风机，当机组设计负荷系数低于70％，且设计转速在1000r／min以下时，动叶调节轴流式风机宜选用双速电动机变极数调节或选用变转速装置(变频器、汽轮机驱动或其他变速装置)调节，在机组较低负荷运行时切换或调节至低转速运行。特别注意：动叶调节轴流式风机在选用变速的调节方式时，应取得制造厂对设备变速运行安全可靠性的保证。
5.5.2 对于静叶调节轴流式风机，当机组设计负荷系数低于80％以下时，静叶调节轴流式风机宜选用变转速装置(变频器、汽轮机驱动或其他变速装置)调节。
5.5.3 对于离心式风机，一般选择入口导向器调节；为得到更佳的经济性，宜选用双速电动机变极数调节或变速装置(变频器、汽轮机驱动或其他变速装置)调节。
5.5.4 对于排粉风机(一般为离心式)通常宜选择入口节流门调节；也可选用入口调节门调节，但应对入口门采取相应的密封和防磨措施。
5.5.5 采用变转速调节的风机，选用何种变速调节装置及其调节范围，应经过详细的技术经济比较来确定。
5.6 风机选型的基本资料
制造厂应提供的基本资料要求如下：
a) 风机选型的必要资料，参见附录A。
b) 对各制造厂所选风机进行评定时，通常需要供应商提供的最少资料参见附录B。
6 风机的运行
6.1 风机的运行区域
6.1.1 为避免高的气流脉动对风机造成危害，离心式风机不应在可能引起喘振的不稳定区域内运行，也不应在气流高脉动区域(如有)内运行，同时还应避免入口调节门开度在30％以下长期运行。
6.1.2 轴流式风机应避免所有可能的运行工况在失速区域(不稳定工况区域)内运行。
6.2 风机的并联运行
6.2.1 两台风机并联运行时系统工作点是由每台风机各自运行点综合而成。若一台风机停止运行，则另一台风机运行点将根据系统阻力特性的需要进行匹配。
6.2.2 对于离心式前弯风机，在停运一台风机时需注意监视风机的电流，以防电动机超载。
6.2.3 对于轴流式风机，单台风机的最大出力取决于动叶(或静叶)的最大运行角度和电动机容量。当要启动停用的风机时，其隔离门宜关闭，叶片角度(动叶调节为动叶角度，静叶调节为调节导叶角度)宜调至最小，当风机达到全速后，隔离门打开。在任何情况下，当第一台风机运行时的压力高于第二台风机失速界线的最低点压力时，不应启动第二台风机进行并联。如需并联，则应降低第一台风机的出力，使其运行点的降低至第二台失速界限压力后再启动第二台风机进行并联。
6.2.4 停用的风机再次启动时，该风机的隔离门和入口调节门均宜关闭，以减少启动阻力矩和启动时间。如果由于上述风门的泄漏而造成风机在启动前反转时，启动应特别谨慎(大型离心式风机特别是引风机宜配备制动或盘车装置)，以防止启动时间过长而损坏电动机。通常，无调速和软启动设备的风机启动时间应限制在25s以内。
6.3 风机运行、维护及检查
6.3.1 风机的运行参数如风量、风压、电流、轴承振动、轴承温度及风机进口和(或)出口的介质温度等，应在控制室内有仪表显示。对轴流式风机宜做到在线监视画面上显示风机运行工况点位于性能曲线上的位置，以便运行人员了解风机的实际运行情况，避免风机在不希望的工况下运行。大型风机的轴承振动和温度还应设有报警信号。所有监视仪表都应定期进行校准。
6.3.2 定期对风机进行维护检查，及时排除运行中出现的故障和异常。主要检查项目有轴承、磨损和腐蚀程度、积灰情况、焊缝和铆接质量、动叶调节轴流式风机的动叶螺栓连接、油系统和调节机构，
包括行程范围、灵活性、各调节叶片动作的一致性，以及实际开度与指示仪表的一致性等。
6.3.3 风机正式投运前，各电厂应根据制造厂提供的资料和管网系统的具体条件，以及安装完毕后的一系列调整试验的结果，编制出具体可行的风机运行操作规程，作为运行人员操作、检查、维护的依据。
