电厂空气预热器柔性接触式密封改造

第31卷第7期华电技术V o.l 31 No .7
2009年7月
H uad ian Techno l o gy
Ju.l 2009
空气预热器柔性接触式密封改造
杜中平1
,杨森1
,杨治国1
,马利君2
,孟金来
2
(1.大唐韩城第二发电有限责任公司,陕西韩城715400;2.北京华能达电力技术应用有限责任公司,北京100070)摘 要:大唐韩城第二发电有限责任公司回转式空气预热器漏风率大大超过设计值,严重影响了电厂的经济效益。

分析了空气预热器漏风的原因,提出用柔性接触式密封技术对空气预热器进行改造,对比改造前、后漏风情况和取得的经济效益,肯定了柔性接触式密封改造技术在回转式预热器的成功应用。

关键词:空气预热器;密封;柔性接触式;漏风;改造
中图分类号:TK 223.34 文献标志码:B 文章编号:1674-1951(2009)07-0057-03
收稿日期:2009-05-21
0 引言
大唐韩城第二发电有限责任公司#
1、#
2锅炉自
投运以来,空气预热器由于机械加工精度和安装精度问题,无论经过检修还是维护保养,长周期运行后密封片都会出现磨损,漏风率远超过设计值。

改造前空气预热器漏风率在15%左右。

1 漏风原因分析
[1]
回转式空气预热器的漏风率一直是困扰电厂锅炉高效率运行的一个重要问题。

回转式空气预热器作为一套转动机械,它的动静结构之间总会存在一定的间隙,这样就使存在压差的空气预热器烟风侧之间产生漏风(主要是空气进入烟气侧),进而造成送、引风机电流的增加和锅炉效率的下降,严重影响电厂的经济效益。

空气预热器漏风形成的原因主要有以下2个:(1)携带漏风。

携带漏风主要是因为空气预热器在转动过程中,一部分驻留在换热元件中的空气被携带到烟气中去,一部分驻留在换热元件中的烟气被携带到空气中去。

这种情况造成的漏风量很小,但这种漏风是空气预热器的构造无法避免的。

(2)直接漏风。

直接漏风主要是由于空气预热器结构本身为保证安全运行而使烟气与空气之间存在一定的间隙;同时,由于烟气和空气之间存在压差也会产生漏风。

直接漏风主要包括径向漏风、轴向漏风、旁路漏风、中心筒漏风。

径向漏风占直接漏风量的80%左右,主要是因为转子上、下端温度差异而发生蘑菇状变形,进而造成密封间隙的增大和漏风率的增加。

转子热变形图如图1所示,转子的冷态和热态情况如图2所示。

2 柔性接触式密封技术理论
传统空气预热器密封技术是刚性有间隙密封技术,在动静间保持一个最小间隙,达到漏风最小。

由于空气预热器存在蘑菇状变形,而且这种变形随负荷环境温度不断发生变化,很难达到一个最佳的动静之间的间隙值。

柔性接触式空气预热器密封技术解决了传统空气预热器密封技术这一薄弱之处,使得动静间隙最小,柔性接触式密封运行示意图如图3所示。

2.1 基本工作原理
将扇形板固定在某一合理位置,柔性接触式密封系统安装在径向转子格仓板上,在未进入扇形板时,柔性接触式密封滑块高出扇形板5~10mm 。

当柔性接触式密封滑块运动到扇形板下面时,合页式弹簧发生形变,密封滑块与扇形板接触,形成严密
#58#华电技术第31卷
表1
i ncone l X -750力学性能
图3 柔性接触式密封运行示意图
无间隙的密封系统。

当该密封滑块离开扇形板后,合页式弹簧将密封滑块自动弹起,以此循环进行。

柔性接触式密封安装立体图如图4所示。

图4 柔性接触式密封安装立体图
2.2 柔性接触式密封系统的特点
(1)采用柔性接触式密封技术,不会形成密封间隙,密封效果好。

由于扇形板与径向密封滑块之间没有间隙,则没有气流通过,也就避免了烟气冲刷磨损的问题,从而保证密封系统长期稳定运行。

(2)采用合页弹簧技术。

该技术允许空气预热器的转子在热态运行状态下有一定的圆端面变形及圆周方向的变形,特别适合空气预热器的改造。

对于围带驱动的空气预热器转子,圆端面有2~3mm 的跳动量是十分普遍的。

空气预热器热态下,圆端面和圆周椭圆度均有不同幅度的变形问题存在,这种技术也可以自动补偿这样的变化。

(3)自润滑合金高温下干磨擦系数L =0.1,对
主轴电机驱动电流影响甚小,增加不超过2A 。

(4)检修工艺简化。

柔性接触式密封系统采用工厂化生产,车间组装成单个密封元件,对原有转子的椭圆度、两端面的平行度、平面度及转子转动跳动量要求降低,大大简化了现场安装的工艺程序且工期较短。

(5)利于空气预热器运行。

传统空气预热器密封采用减小密封间隙的方法来减少漏风,当负荷变化剧烈或有其他异常工况时,易造成空气预热器卡涩或电机电流摆动大。

柔性接触式密封采用弹簧技术,硬密封间隙可放大,减少卡涩现象发生。

(6)密封状况随年限运行漏风量变化平缓。

2.3 材料及设计计算
密封滑块采用一种高科技材料)))自润滑合金,此种材料在高温无润滑脂的条件下,可以达到很低的摩擦系数,具有耐磨损、耐高温、摩擦系数小、安装方便及更换组件快捷的优点。

该材料的主要性能指标为:密度Q ,7.54g /m 3
;硬度,80~300H B ;干摩擦系数L ,0.05~0.20;抗压强度,355MPa ;抗弯强度,275M Pa ;适用速度,0.3~2.5m /s ;适用温度,-30~550e ;年磨损量(圆周处),0.36mm;弹性模量E ,1.83@105
MPa ;膨胀系数A ,10.72@106
;切变模量G ,80.4@103M Pa 。

接触式密封技术的另一核心技术是弹簧,该弹簧材料为inconel X -750,是以A ,l T,i Nb 强化的镍基合金,是inconel 合金系统中早期发展的应用广泛的合金之一。

合金在980e 以下具有良好的强度、抗腐蚀和抗氧化性能,而且也有较好的低温性能,成形性能也较好,能适应各种焊接工艺。

该材料的力学性能见表1。

3 实施方案
2008年10月和2009年4月,大唐韩城第二发电有限责任公司#
1、#
2锅炉空气预热器进行柔性接触式密封改造,具体改造范围如下:
(1)调整冷、热端扇形板到合理位置,并按新的设计方案进行扇形板静密封的维修及部分更换工作;
第7期杜中平,等:空气预热器柔性接触式密封改造#59#
(2)热端径向、冷端径向固定密封片修复,并按厂家设计要求调整;
(3)热端径向、冷端径向柔性接触式密封安装;
(4)旁路密封局部更换,并按厂家设计要求调整;
(5)轴向密封修复,并按厂家设计要求调整;
(6)其他空气预热器漏风处理。

4改造后效果及经济效益分析
密封改造前,#1、#2锅炉空气预热器的平均漏风率为15%左右,进行柔性接触式密封改造后,在锅炉ECR工况下,空气预热器的漏风率平均为4.6%,达到了国外5%~8%的先进水平[2]。

(1)年节约费用。

按漏风率15%计算,一般漏风率下降12%,可提高锅炉效率1%。

主要来自锅炉排烟热损失的减少和引风机、送风机、一次风机电耗的下降。

按改造后空气预热器的漏风率4.6%计算,则锅炉效率提高0.87%,可减少煤耗=330g/(k W#h)@ 0.87%=2.871g/(k W#h)。

按机组年利用小时6000h,标准煤单价600元/t计算,则每台锅炉年节约费用=6000h@2.871g/(k W#h)@1000@103 k W@600元/t=1033(万元)。

(2)除节煤一项每年可节约1033万元外,由于引风机、送风机、一次风机长时间运行而带来的电耗的上升因此次技术改造而大大降低,由此带来的经济效益非常可观。

5结论
大唐韩城第二发电有限责任公司空气预热器采用柔性接触式密封技术改造后,目前运行平稳,密封效果好,漏风率大幅下降,具有很好的节能效果,经济效益明显。

参考文献:
[1]张春生.回转式空气预热器漏风分析与解决方案[J].热
电技术,2006(4):15-17.
[2]周英文;任勤让.回转式空气预热器漏风大的原因及改
进[J].电力建设,2002,23(6):12-14.
(编辑:刘芳)
作者简介:
杜中平(1968)),男,山西孝义人,设备部主任,高级工程师,从事电厂设备检修方面的工作。

杨森(1980)),男,陕西高陵人,锅炉专工主管,工程师,从事电厂设备检修方面的工作。

杨治国(1973)),男,陕西澄城人,设备部主任助理,工程师,从事电厂设备检修方面的工作。

马利君(1958)),男,宁夏银川人,总经理,高级工程师,从事电力设备管理方面的工作。

孟金来(1957)),男,宁夏石嘴山人,总工程师,高级工程师,从事电力设备研发方面的工作。

(上接第52页)
(3)当给水泵汽轮机转速到达3554r/m i n,而且ENABLE RMO SETP灯亮时方允许切换为遥控转速设定值,在ENABLE RMO SETP灯亮之前进行R MO/I N T的切换没有任何意义。

若给水泵汽轮机转速已经到达3554r/m i n且已将控制器打到遥控位,给水泵汽轮机转速升速率仍没释放,则是因为给水泵汽轮机缸体温度没有到达220b C,此时只需等待,当缸体温度到达220b C时便可自动释放升速率。

(4)由于辅汽供给水泵汽轮机管道较细,在给水泵汽轮机启动过程中,可能会造成机前压力过低(当机前压力大于0.25M Pa时允许启动给水泵汽轮机,可见压力太低时,对给水泵汽轮机安全运行不利),当机前的辅汽压力低于0.3M Pa时,极有可能会因为相同的原因导致给水泵汽轮机跳闸,在给水泵汽轮机启动过程中,运行人员需加强对机前辅汽压力的的监控。

由于限值产生回路存在150r/m i n的回差(回差值可适当改小,需汽轮机专业认可),实际上当转速高于3704r/m in时,方可认为转速已大于3554r/m in。

为了提高给水泵汽轮机启动时的可靠性,请使用给水泵汽轮机子组完成启动过程,在给水泵汽轮机子组没有将转速切换为遥控设定值之前,不要进行不必要的操作。

(编辑:王书平)
作者简介:
毕华南(1976)),男,河北邯郸人,工程师,主要从事电厂集控运行方面的工作。

李红艳(1976)),女,河北邯郸人,助理工程师,从事电厂仪控技术方面的工作。

#80#Abstracts第31卷
09-07-41The reason analysis on m issi n g oper-ation of safety st ability device and ant-i accident m easures
W U K ai(Dong feng H ydropowe r P lan t,Q i ngzhen563001, Ch i na)
Abstrac t:Dong feng H ydropowe r P lant has p layed a ro l e o f break po i nt o f sout h po w er gr i d and north power gr i d of G u i yang for a-ges.In its safety stab ility dev ice,there i s a tac tics to treat t he /one li ne tripping and another li ne ov erload i ng0accident of east m a i n double c ircu i t w hich is very i m portant for t her m a l stability and safety o f220k V outpu t cab l es of D ong feng H ydropo w er P lant.In2008,A ugust29,the eastm a i n c i rcuit N o.2tr i pped, and t hen the eastm a i n circu it N o.1w as overload,but t he sa fety stability dev ice of D ong feng H ydropo w er P l ant didn t'execute t he establi shed overload trea t m ent tac tics.T he reason of the acc-i dent and the an t-i acc i dent m easures w ere analyzed and i ntro-duced,and a propo sa l about t he criter i on o f re levant tactics for the dev ice was put f o r w ard.
K ey word s:sa fety stab ility dev ice;trip;circu it overload;tac-ti cs;ant-i acc i den tm easures
09-07-44Analysis of a shut-down accident caused by auto m atic air s w itch tri p
GUAN Yu-j i an(Guangzhou H engyun Pow er P lant,G uangzhou 510000,Ch i na)
Abstrac t:In a certa i n po w er plan t,afte r an auto m a tic a ir s w itch in seconda ry c ircuit o f po tential transf o r m er o f6k V aux ili ary w ork i ng bus section of N o.7un it tri p w as discussioned.T he d i s-tr i buted contro l syste m had m istake the fau lt f o r that the vo ltage o f aux ili a ry worki ng bus section i s cut of,f and sen t out operati on instructi on to trip the6kV po w er b reaker.In the process of vo l-t age i nterrupt and transfer of w ork i ng bus secti on,the coa l feed breaker tri pped due to the m o m entary vo ltage i nterrupt,and t h is lead t he m a i n fuel tri ppi ng pro tecti on breaker to tr i p.A t last, the U nit w as disconnected w ith the syste m.T he reason of t h is acc i den t outag e was ana l y zed,and the preven tive measures o f si m ilar acc i den tw ere propo sed.
K ey word s:secondary circu it of po tential transfor m e r;auto m a tic air s w itch;vo ltage i nte rrupt;shut do w n;analysis;preventi ve m easures
09-07-46Installation technique of water cooled oscillating grate in boiler
YUAN G en-yong(A nhui E lectr ic P o w er Constructi on F irst En-g i neer i ng Corporati on,H efe i230088,Ch i na)
Abstrac t:A s an equ i p m en t f o r b i om ass power genera tion,t he w ater coo l ed o sc illati ng grate can ensure the straw to burn full y. T he i nsta ll ation qua lity of w ater coo led o sc illati ng g rate w ill d-i rectly i nfl uence on econom i ca l bene fit o f pow er p l ant.T he i n-sta llation technique of w ater cooled o sc illati ng g rate w as i ntro-duced in deta i,l and the m atters need i ng a ttenti on i n insta llati on process w ere proposed to ensure the i nsta llati on qua lity o f w ater coo led osc ill a ti ng g ra te to be ex ce llent and t he de m and of po w er plant operati on to be sa tisfi ed.
K ey w ords:stra w;w ater coo l ed o sc illati ng grate;i nstall a tion
09-07-48Reason analysis of vane servo m otor fault and handli n g
X I AO Yu e-dong(Guangdong Y udean Q i ngx i P o w er G enera ti on Co rpo ra ti on L i m ited,D apu514200,Ch i na)
Ab stract:A ccord i ng to t he fau lt pheno m enon o f vane se rvo m o t o r of unit speed governor,t he fault reason of vane ope ration system was ana l yzed.T he fault po i n tw as defi n ited by us i ng the e li m ina-tion m et hod.Co m bi n i ng the prac tica l situati on,the fi xed-b l ade operation m ode w as adopted,wh ich was used as a e m ergency trea t m en t for hydroelectr ic genera ti on set and for ensuri ng safety operation o f the g enerati on set.
K ey w ords:hydroe l ectric po w er p l ant;speed governor;vane se rvo m o t o r
09-07-50A nalysis of proble m s i n application and start up of contro l syste m of steam turbi n e for feedwater pu m p
B I H ua-nan,L I H ong-yan(H uaneng H anfeng Pow er P l ant, H andan056200,Ch i na)
Ab stract:T he serv i ce conditi on of contro l syste m of the stea m turb i ne for bo iler feed w ater pu mp produced by S i e m ens was dis-coursed.T he control pri nc i ple of t he syste m w as i ntroduced.T he a ll process,in wh i ch inc l udes t he measurement of speed i m pu l se si gna,l the for m ati on o f speed setti ngs,and the crea ti on of contro l i nstructi on for the stea m t urb i ne speed,w ere descri bed i n detai.l Combi n i ng w ith the concre te service conditi on of the system i n stea m turb i ne f o r f eed w ater pu m p,so m e proble m s occurred in op-erati on and handli ng m ethods were expla i ned terse l y.
K ey w ords:speed m easure m ent v al ue;speed setti ng va l ue;cold state;hot sta te;speed control
09-07-53A nalysis and deter m i n ation of t he rake capacit y of rotary trash raking equip m ent
W ANG Xu,YANG Jun-jing(Jiangsu P rov i nce W ater Conse r-vancy Survey&D esi gn R esearch Institute Corporati on L i m ited, Y angzhou225009,China)
Ab stract:By compar i ng of t he c lean i ng capacity o f used trash re m overs w i th each o t her,comb i n i ng w it h eng i neer i ng use expe-r i ence,it is po i nted out t hat f o r t he trash re m oversw ith d ifferent or ifi ce,t he re m ov i ng capac ity ana l ys i s and calcu lati on o f the trash re m over is necessary to de ter m i ne rationa l param eters and to avo i d desi gn e rror w hich cou l d cause t he c l eani ng capac it y i n-suffic i ent or excess o f tras h remover.
K ey w ords:rotary rak i ng equip m ent;rake capacity;pa ra m e ter ca l culati on
09-07-57R ef or m ation of air preheater adop-ti n g flexible cont act m ode sealing techno l o gy
DU Zhong-p i ng1,YANG Sen1,YANG Zh-i guo1,MA L-i
第7期Abst racts#81#
j un2,MENG Jin-lai2(1.Da tang H ancheng Second P o w er
G enera ti on Co rporati on L i m ited,Ch i na D atang Co rpo ra ti on,
H ancheng715400,Ch i na;2.Be iji ng H uanengda E lectr ic T ech-n i que A pplica ti on Corporati on L i m ited,Be iji ng100070,Ch i na) Abstrac t:The rota ry a ir prehea ter leakage ratio of Da tang H ancheng Second Powe r G eneration Co rpo ra ti on L i m ited were g reatly exceeded t he desi gned va l ue,and t h is ser i ously i nfl u-enced on econo m ica l bene fit o f t he pow er plant.T he reason o f air-preheater leakage w as analyzed,and a refor m ation m ethod by us i ng fl ex i b l e contact-type sea li ng techno l ogy was presen-ted.B ased on t he comparison of a ir l eakages and econo m ical bene fits be f o re and a fter refor m a ti on,it can be con fi r m ed that the app licati on o f flex i b le contact type seali ng techno l ogy i n ro ta-ry a ir prehea ter re for m ati on is successf u.l
K ey word s:a ir preheate r;sea;l flex i b le contact-type;a ir leak-age;refor m ation
09-07-60Applicati o n of fl u e gas damper in re-heat te m perat ure adjust m ent
T I AN Ji an-zhou(F eng ta i P o w er G ene ra tion Branch o fH ua i zhe Coal and P o w er Co rpo ra ti on L i m ited,F engta i232131,Chi na) Abstrac t:T ak i ng a600MW supe rcr iti ca l bo il e r o f Feng ta iP o w er G enera ti on Branch ofH ua izhe Coa l and Pow er Co rporati on L i m i-t ed as exa m ple,the appli cation o f t he fl ue gas damper i n reheat te m pera t ure adj ust m ent w as i ntroduced.The contro l princ i p l e o f fl ue gas da m per,t he practica l applicati on and the m atters nee-d i ng a tten ti on i n applica ti on w ere expounded.The prob l em s caused by flue gas damper w ere summ arized,and so m e i m pro-v i ng m easures w ere g iven.
K ey word s:supercritica l bo iler;fl ue gas damper;reheat te m-perature adjust ment;practical applica ti on;i m prov i ng m easure
09-07-62Treat m e nt of signal i n terference i n frequency converter
W ANG Yon g-jun(Zheji ang P rovince T her m a l Pow er Construc-ti on Co m pany,H angzhou310016,Chi na)
Abstrac t:The bas i c t ypes o f si gna l i n terfering in frequency con-verter w ere i ntroduced.T he reason o f si gnal i n terference i n fre-quency converter o f2@1000MW u ltra s uperc ritica l un its of Be-i l ungang P o w er P l ant pro ject phase III was ana l yzed,and con-crete treat ment m ethod w as g iven.
K ey word s:frequency conve rter;si gnal i nterfe rence;treat m ent m ethod
09-07-65Application of low te m perat ure m ult-i effective distil m ent seawater desali n ati o n technology
SUN Yu-w en,ZHOU Jun(Be ijing Guodian N o rt h Ch i na P o w er Eng i neering Corporati on L i m ited,Beiji ng100120,China) Abstrac t:T he sea water desa li nation techno l ogy i nc l udes t he d i still a ti on m ethod and the reverse os mos i s m et hod.T he app lica-ti on of l ow te m perat ure m ult-i effecti ve distillation techno l ogy i n T ian jin Be ijiang P o w er P lantw as i ntroduced.T he features o f sea w ater desali nati on techno l ogy w ere analyzed.The operati on and con tro lm ode of sea wa ter desa li nation syste m w ere discoursed. T he perfor m ance pa rame ters and guaranteed va l ue of t he sea wa-te r desa li nati ng equ i p m ent were g i ven.
K ey w ords:sea w ater desa li na ti on techno logy;sea w ater desa l-i na ting equ i p m ent;low temperature mu lt-i e ffecti ve distillation; sea w ater reverse os mo si s;perfor m ance param eters
09-07-68Analysis and debuggi n g on do m estic se wage recycle treat m ent syste m
L I Chang-zh,i DUAN Bo,L I Zhong-xiu,SONG H ong-jun, MA Yan-m i n(Fu l ar ji G eneral P o w er P lan t,Ch i na Huadian Co r-poration,Q iqi har161041,China)
Ab stract:A ccordi ng to the che m ica lm on itor analysis and debug-g i ng o f the latter l y bu ilt do m estic sewage recycle treat ment syste m i n H uadian Fular jiG eneral E l ectric Po w er P lant of Chi na Huad i an Corporati on,the pr i nci p l e,the treati ng ability and t he process flo w o f domesti c se w age treat m ent system w ere discussed.F ur-ther mo re,t he m eani ngs of each che m i ca lmonitor para m etersw ere exp l a i ned.W ith the running of the syste m,the plant ach i eved the bene fit o f waste w ater recyc li ng and zero e m issions.
K ey words:dom estic sewage;b i o log ical trea t m ent;soften i ng hand li ng;b i ochem ica l oxygen demand;chem ical oxygen de-m and;suspended so li ds
09-07-73A pplication of e lectrostatic-bag pre-ci p itator in high capac ity ther m al pow er generation unit
W ANG Yong1,DONG Xu e-feng2,JI ANG D e-hou2,REN Z hen-we i3(1.H uad i an X i nx i ang Pow er G ene ration Co rpo ra ti on L i m i ted,X i nx i ang453635,Chi na;2.H enan E l ec tric Powe r T est and R esearch Institute,Zheng zhou450052,Ch i na;3.H uad i an Qudong T her m al Pro j ect P repare Constructi on Deprat m ent, X i nx iang453000,Ch i na)
Ab stract:E lectrostatic-bag prec i p itator is nove l dust remova l e-qu i p m ent developed by co m b i ning t he advantages o f electrostatic prec i p itator and baghouse,it i s espec i a lly suitable to refo r ma ti on of e lectro sta ti c prec i pita tor.Co m bini ng w ith a refor m ati on pro j ect of e lectrostati c prec i p itator i n dom estic660MW ther m al pow er generation un it,the app licati on of e lectrostati c-bag prec i pita t o r i n high capac ity pow er g enerati on unit w as d i scussed.
K ey w ords:electrostatic-bag prec i pita t o r;refor m ation of e l ectro-static prec i pita t o r;ther m a l po w er generati on un it;app licati on
09-07-76A nal y sis of oi-l savi n g m ethod i n unit starti n g-up and shutting-dow n
CHEN Tao,Q I U Guan g-fu(G uizhou D afang Pow er G enerati on Co rpo ra ti on L i m ited,D afang551600,Ch i na)
Ab stract:A i m i ng at the present o il consu m pti on of coa-l fired bo iler,comb i ning w ith t he features of bo iler dev i ces,syste m and operation mode,the three per i od in starti ng-up process,wh i ch have greater o i-l sav i ng po tentia,l w ere ana l y zed e m phatica lly, and concrete o i-l sav ing m easures w ere proposed.T he obv ious effect w as ob tained by adopti ng these measures.
K ey w ords:bo iler;f ue l oi;l start-up and shu t down;o i-l sav ing。