循流化床鍋爐基礎知識

1、循流化床鍋爐基礎知識循流化床鍋爐基礎知識1Basic Knowledge of Circulating Fluidized Bed Boiler一次風機二次風機引風機高壓鼓風機爐膛省煤器過熱器旋風分離器風箱空氣預熱器ESP煙囪高二次風低二次風 1.1循流化床鍋爐的概念循流化床鍋爐的概念 1.1Concept of Circulating Fluidized Bed Boiler 采用循環(huán)流化床燃燒技術，燃用固體燃料的鍋爐就是循環(huán)流化床鍋爐。固體顆粒（燃料、底渣、循環(huán)灰、石灰石、砂子等）在爐膛內(nèi)以流態(tài)化的方式運動，被流化風帶走的部分顆粒經(jīng)分離器分離，送回爐膛循環(huán)燃燒。爐膛內(nèi)的顆粒濃度高，燃燒、傳

2、質(zhì)、傳熱劇烈，溫度分布均勻。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.什么叫循環(huán)流化床Section 1 what is circulating fluidized bed boiler 循環(huán)流化床鍋爐的工作過程大致為：燃料及石灰石脫硫劑經(jīng)破碎至合適粒度后，由給煤機和給料機從流化床燃燒室布風板上部給入，與燃燒室內(nèi)熾熱的沸騰物料混合，被迅速加熱，燃料迅速著火燃燒、石灰石則與燃料燃燒生成的SO2反應生成CaS04，從而起到脫硫作用。燃燒室溫度控制在850左右。在較高氣流速度的作用下，燃燒充滿整個爐膛，并有大量固體顆粒被攜帶出燃燒室，經(jīng)高溫旋風分離器分離后，一部分熱爐料直接送回流化床燃燒室繼續(xù)參與燃燒；另部分則送至外置床換熱器，在外置床換熱器中與受熱面和空氣

5、進行熱交換，被冷卻至400600后，經(jīng)送灰器送回燃燒室或排出爐外。經(jīng)旋風分離器導出的高溫煙氣，在尾部煙道與對流受熱面換熱后，通過布袋除塵器或靜電除塵器，由煙囪排出。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. 循環(huán)流化床鍋爐的一些基本名稱術語 Section 2 some basic technical terms of the CFB boiler 1.物料 Material 在循環(huán)流化床爐膛以及循環(huán)系統(tǒng)內(nèi)的，參與燃燒和熱傳遞的固體物質(zhì) 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，包括靜止的或流化狀態(tài)的，或者從功能上講將要用作床料的材料 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. 密相區(qū) Dense region 在流化床鍋爐爐膛下部，顆粒濃度較大，這部分區(qū)域稱為密相區(qū)，密相區(qū)內(nèi)沿高度方向濃度逐漸降低。循環(huán)流化床鍋爐中，一般定義密相區(qū)低于二次風噴口高度 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. 稀相區(qū) Dilute region 在流化床鍋爐爐膛上部，氣流中粒子濃度較低，稱為稀相區(qū).稀相區(qū)內(nèi)顆粒濃度比較均勻，沿爐膛高度顆粒濃度變化比較緩慢。循環(huán)流化床鍋爐中，一般定義稀相區(qū)為鍋爐下部錐段以上直段500mm以上為稀相區(qū)。 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. 過渡區(qū) Transition region 在流化床鍋爐密相區(qū)和稀相區(qū)之間，顆粒濃度處于沿高度快速變化狀態(tài)，存在比較大的揚析與夾帶現(xiàn)象，稱為過渡區(qū)。 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. 料層壓差-將布風板下風室壓力和密相區(qū)頂部壓力接入壓差計，作為燃燒控制和排渣的一項參數(shù)。懸浮段差壓將密相區(qū)頂部壓力和爐膛出口壓力接入差壓計，作為鍋爐循環(huán)物料量控制的一項參數(shù)。密相區(qū)內(nèi)安裝帶有防磨套管的熱電偶來監(jiān)視溫度，熱電偶露出爐墻的長度為100150mm，在控制室

17、內(nèi)用數(shù)字顯示溫度。 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. 壓火 Banking fire 壓火是流化床鍋爐特有的一種停爐操作，它是在運行中迅速停掉鍋爐的燃料和送風及其它一切輻機運行，讓鍋爐處在保溫保壓狀態(tài)并保持水位正常的操作過程。壓火的目的一般是為了處理一些不需要徹底停爐就

20、能在短時間內(nèi)處理好的設備故障，以便問題排除后鍋爐能快速啟動。 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.揚火 Releasing fire揚火就是將處壓火狀態(tài)的鍋爐快速啟動的操作過程，根據(jù)啟動前床溫的高低不同，揚火啟動又可分為熱態(tài)啟動和溫態(tài)啟動。熱態(tài)啟動是指啟動前床溫較高，一般在700以上，這時啟動風機后可以直接加煤，不需要投入油槍助燃，整

22、個啟動時間一般4060分鐘。溫態(tài)啟動時指啟動時床溫較低，一般低于煤的著火溫度，這時，在加燃料之前，需要投入油槍助燃將床溫提高到燃料的著火點以上，這一啟動過程一般需要2個小時左右時間。 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. 循環(huán)流化床技術的特點 technical characteristics of CFB 1.燃燒特點 Combustion characters 1.1低溫動力控制燃燒 Low tem

25、perature dynamical control combustion 1.2高速度、高濃度、高通量的固體物料流態(tài)化循環(huán)過程 The circulating process of solid material in fluidized state with high speed, high consistence, and high flux. 1.3高強度的熱量、質(zhì)量和動量傳遞過程 With a transfer process of high intensity heat, mass and momentum 2.循環(huán)流化床技的優(yōu)點Advantages of the CFB techn

26、ology2.1燃料適應性廣 the wide adaptability of fuel 2.2 燃燒效率高 the high efficiency of combustion2.3可以爐內(nèi)脫硫 Can achieve the desulphurization in the furnace2.4NOx排放量低 the low emission of NOx2.5調(diào)峰性能好 the good performance of load adjustment2.6燃料制備、給煤系統(tǒng)簡單 the simple designs for fuel preparation and conveying syst

27、em 2.7灰渣可以綜合利用 the fly ash and bottom ash can be used as material for constructing industrial or for the foundation of high-way 此外，CFB鍋爐還具有傳熱系數(shù)高、可以壓火運行、不存在爐內(nèi)和受熱面結渣、不會滅火放炮，其它污染物如CO、HCl、HF等的排放量也很低等優(yōu)點。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鍋爐主要系統(tǒng)組成簡介 A brief introduction of the main systems for CFB boiler 循環(huán)流化床鍋爐系統(tǒng)主要包括鍋爐本體系統(tǒng)和鍋爐輔助系統(tǒng)兩部分。鍋爐本體系統(tǒng)主要包括燃燒系統(tǒng)與汽水系統(tǒng)。鍋爐輔助系統(tǒng)包括煤與石灰石系統(tǒng)、煙風系統(tǒng)、灰處理系統(tǒng)、鍋爐控制系統(tǒng)、點火系統(tǒng)等。下圖為循環(huán)流化床鍋爐系統(tǒng)及其組成示意圖。 CFB boiler system includes mainly two parts, they