循流化床锅炉基础知识

1、循流化床锅炉基础知识循流化床锅炉基础知识1Basic Knowledge of Circulating Fluidized Bed Boiler一次风机二次风机引风机高压鼓风机炉膛省煤器过热器旋风分离器风箱空气预热器ESP烟囱高二次风低二次风 1.1循流化床锅炉的概念循流化床锅炉的概念 1.1Concept of Circulating Fluidized Bed Boiler 采用循环流化床燃烧技术，燃用固体燃料的锅炉就是循环流化床锅炉。固体颗粒（燃料、底渣、循环灰、石灰石、砂子等）在炉膛内以流态化的方式运动，被流化风带走的部分颗粒经分离器分离，送回炉膛循环燃烧。炉膛内的颗粒浓度高，燃烧、传

2、质、传热剧烈，温度分布均匀。The circulating fluidized bed boiler (CFB boiler) is a kind of boiler which utilizes the combustion technology of circulating fluidized bed, and fired with solid fuel. The solid particles (fuel, bottom slag, circulating ash, limestone, sand, etc.) are moving in the way of fluidized sta

3、te in the furnace. The partial particles taken away by air are separated by separators, and then return back to the furnace for circulating combustion. In the furnace, consistence of particles is high, the distribution of temperature is even, combustion, material conveying, and heat transfer are vio

4、lent.什么叫循环流化床Section 1 what is circulating fluidized bed boiler 循环流化床锅炉的工作过程大致为：燃料及石灰石脱硫剂经破碎至合适粒度后，由给煤机和给料机从流化床燃烧室布风板上部给入，与燃烧室内炽热的沸腾物料混合，被迅速加热，燃料迅速着火燃烧、石灰石则与燃料燃烧生成的SO2反应生成CaS04，从而起到脱硫作用。燃烧室温度控制在850左右。在较高气流速度的作用下，燃烧充满整个炉膛，并有大量固体颗粒被携带出燃烧室，经高温旋风分离器分离后，一部分热炉料直接送回流化床燃烧室继续参与燃烧；另部分则送至外置床换热器，在外置床换热器中与受热面和空气

5、进行热交换，被冷却至400600后，经送灰器送回燃烧室或排出炉外。经旋风分离器导出的高温烟气，在尾部烟道与对流受热面换热后，通过布袋除尘器或静电除尘器，由烟囱排出。Generally, the working process of CFB boiler is that after fuel and limestone are crushed into proper particle sizes, they are conveyed to the combustion chamber above the air distributor, by coal feeders and material

6、feeders and then they are mixed with hot fluidized material to be heated up rapidly. Thus, fuel catches fire quickly and burn, limestone reacts with SO2, which fuel burns and generated, to produce CaS04, so that can we have the desulphurizing function. The chemical reaction equations are as follows:

7、C + O2 CO2C + O2 CO2CO + O2 2CO2CaCO3 CaO + CO2S + O2 SO2CaO + SO2 CaSO32CaSO3 + O2 CaSO4The temperature of combustion chamber should be controlled to about 850. Under the influence of high speed air flow, the combustion is full of furnace, and a lot of solid particles have been carried out from the

8、 combustion chamber and to be separated by high temperature cyclone separator. And then a part of the separated material is directly returned to the combustion chamber to combust continuously, and the other part is sent to a external heat exchanger, Which is also a small fluidized bed, where occurs

9、the heat exchange with the heating surface and air. Out from the external heat exchanger, it is cooled to 400600, and then through the ash conveyer it is sent back to the combustion chamber or is discharged to ash silo. The high temperature flue gas, goes through the cyclone separator into the verti

10、cal flue, exchanges heat with convection heating surfaces, then, discharged from the chimney after purified by the bag filter or the electrostatic precipitator. 循环流化床锅炉的一些基本名称术语 Section 2 some basic technical terms of the CFB boiler 1.物料 Material 在循环流化床炉膛以及循环系统内的，参与燃烧和热传递的固体物质 Material, here refers

11、to the solid substance in the furnace and the circulating system, which take part in the combustion and heat transfer. 2.床料 Bed material 床料是指存在于床面上的物料，包括静止的或流化状态的，或者从功能上讲将要用作床料的材料 Bed material refers to the material that on the bed, either in fluidized or in stable state, or for the function, such m

12、aterial which will be used as bed material, even if not exists on the bed. 密相区 Dense region 在流化床锅炉炉膛下部，颗粒浓度较大，这部分区域称为密相区，密相区内沿高度方向浓度逐渐降低。循环流化床锅炉中，一般定义密相区低于二次风喷口高度 At the lower part of the CFB boiler furnace, the particle consistence is high. So this area is called the dense region. The consistence i

13、n the dense region is reduced gradually along the height direction. In the CFB boiler, generally the dense region is defined below the height of the secondary air spout. 稀相区 Dilute region 在流化床锅炉炉膛上部，气流中粒子浓度较低，称为稀相区.稀相区内颗粒浓度比较均匀，沿炉膛高度颗粒浓度变化比较缓慢。循环流化床锅炉中，一般定义稀相区为锅炉下部锥段以上直段500mm以上为稀相区。 At the upper par

14、t of the furnace of a CFB boiler, the particle consistence in the airflow is low, so this area is called the dilute region .In the dilute region, the particle consistence is comparatively even and changes slow along the height of the furnace. To a generally definition, the dilute region is the strai

15、ght section of the furnace that 500mm high above the cone-shaped segment. 过渡区 Transition region 在流化床锅炉密相区和稀相区之间，颗粒浓度处于沿高度快速变化状态，存在比较大的扬析与夹带现象，称为过渡区。 The particle consistence between the dense and the dilute region of a CFB boiler, changing rapidly in the height direction, the consistence and space r

16、atio are between the two regions, so it is called the transition region. The state in this region is not stable, there exists apparent eruption and carrying phenomena. 料层压差-将布风板下风室压力和密相区顶部压力接入压差计，作为燃烧控制和排渣的一项参数。悬浮段差压将密相区顶部压力和炉膛出口压力接入差压计，作为锅炉循环物料量控制的一项参数。密相区内安装带有防磨套管的热电偶来监视温度，热电偶露出炉墙的长度为100150mm，在控制室

17、内用数字显示温度。 1 Differential pressure of material layer - the pressure of air room which is below the air distributor and the top pressure of dense are should be connected into the differential pressure meter, and it could be regarded as a parameter of the combustion controlling and the slag discharging

18、. 2 Differential pressure of the suspension section - The top pressure of dense area and the furnace outlet pressure should be connected into the differential pressure meter, and it could be regarded as a parameter of the controlling of boiler recycle material. 3 The thermocouple with the anti-wear

19、sleeve should be installed in the dense area to monitor the temperature, the exposed length of the thermocouple is 100150mm, and the temperature is shown with numbers in the controlling room. 压火 Banking fire 压火是流化床锅炉特有的一种停炉操作，它是在运行中迅速停掉锅炉的燃料和送风及其它一切辐机运行，让锅炉处在保温保压状态并保持水位正常的操作过程。压火的目的一般是为了处理一些不需要彻底停炉就

20、能在短时间内处理好的设备故障，以便问题排除后锅炉能快速启动。 Banking fire is a kind of special shutting down operation of CFB boiler, it is an operating process which will stops the fuel feeding and air supply quickly and stops all the auxiliary equipment at the same time, keeps the boiler at high pressure and temperature with a

21、 normal water level. The aim of banking fire is to deal with some fault which can be settled in a short time and need not shut down the boiler completely, so as to start up quickly.扬火 Releasing fire扬火就是将处压火状态的锅炉快速启动的操作过程，根据启动前床温的高低不同，扬火启动又可分为热态启动和温态启动。热态启动是指启动前床温较高，一般在700以上，这时启动风机后可以直接加煤，不需要投入油枪助燃，整

22、个启动时间一般4060分钟。温态启动时指启动时床温较低，一般低于煤的着火温度，这时，在加燃料之前，需要投入油枪助燃将床温提高到燃料的着火点以上，这一启动过程一般需要2个小时左右时间。 Releasing fire is the operating process that start up the boiler which in the state of banking fire. according to the bed temperature, this process is divided into hot start and warm start. The hot start refe

23、rs to that the bed temperature is higher, generally, above 700,you can feeding fuel after the fans be started up, without putting the oil gun to assist the combustion, commonly, the time of the whole process is about 4060 minutes. The warm start refers that the bed temperature is lower than the burn

24、ing point of the fuel before the boiler is going to be started up, you should put the oil guns in use to increase the bed temperature over the burning point, generally, it will spend 2 hours for this course. 循环流化床技术的特点 technical characteristics of CFB 1.燃烧特点 Combustion characters 1.1低温动力控制燃烧 Low tem

25、perature dynamical control combustion 1.2高速度、高浓度、高通量的固体物料流态化循环过程 The circulating process of solid material in fluidized state with high speed, high consistence, and high flux. 1.3高强度的热量、质量和动量传递过程 With a transfer process of high intensity heat, mass and momentum 2.循环流化床技的优点Advantages of the CFB techn

26、ology2.1燃料适应性广 the wide adaptability of fuel 2.2 燃烧效率高 the high efficiency of combustion2.3可以炉内脱硫 Can achieve the desulphurization in the furnace2.4NOx排放量低 the low emission of NOx2.5调峰性能好 the good performance of load adjustment2.6燃料制备、给煤系统简单 the simple designs for fuel preparation and conveying syst

27、em 2.7灰渣可以综合利用 the fly ash and bottom ash can be used as material for constructing industrial or for the foundation of high-way 此外，CFB锅炉还具有传热系数高、可以压火运行、不存在炉内和受热面结渣、不会灭火放炮，其它污染物如CO、HCl、HF等的排放量也很低等优点。In addition, CFB boiler also have the advantages of the high coefficient of heat transfer, banking fir

28、e running, no slag formation inside the boiler and on the heating surface, no flameout and explosion, the low emission of other contaminations, such as: CO、HCl、HF, etc. CFB锅炉主要系统组成简介 A brief introduction of the main systems for CFB boiler 循环流化床锅炉系统主要包括锅炉本体系统和锅炉辅助系统两部分。锅炉本体系统主要包括燃烧系统与汽水系统。锅炉辅助系统包括煤与石灰石系统、烟风系统、灰处理系统、锅炉控制系统、点火系统等。下图为循环流化床锅炉系统及其组成示意图。 CFB boiler system includes mainly two parts, they are