蒸汽流量計量的特點
(一)飽和蒸汽流量計量中的兩相流
在(zai)對(dui)蒸(zheng)汽(qi)流(liu)量(liang)進(jin)行(xing)計(ji)量(liang)時(shi),由(you)於(yu)當(dang)戶(hu)側(ce)用(yong)都(dou)多(duo)為(wei)飽(bao)和(he)蒸(zheng)汽(qi),在(zai)對(dui)蒸(zheng)汽(qi)質(zhi)量(liang)進(jin)行(xing)特(te)殊(shu)量(liang),多(duo)以(yi)千(qian)度(du)為(wei)進(jin)行(xing)衡(heng)量(liang),即(ji)於(yu)飽(bao)和(he)蒸(zheng)中(zhong)含(han)水(shui)量(liang)可(ke)以(yi)忽(hu)路(lu)不(bu)計(ji),而(er)顯(xian)飽(bao)和(he)蒸(zheng)汽(qi)中(zhong)含(han)水(shui)量(liang)較(jiao)大(da),這(zhe)就(jiu)會(hui)導(dao)致(zhi)在(zai)對(dui)飽(bao)和(he)蒸(zheng)汽(qi)流(liu)量(liang)測(ce)量(liang)時(shi)會(hui)存(cun)在(zai)兩(liang)相(xiang)流(liu)的(de)問(wen)題(ti)。
(二)蒸(zheng)汽(qi)流(liu)量(liang)計(ji)量(liang)中(zhong)的(de)蒸(zheng)汽(qi)密(mi)度(du)補(bu)償(chang)蒸(zheng)汽(qi)在(zai)壓(ya)力(li)和(he)溫(wen)度(du)不(bu)可(ke)能(neng)保(bao)持(chi)在(zai)一(yi)個(ge)水(shui)平(ping)恒(heng)久(jiu)不(bu)變(bian)其(qi)會(hui)處(chu)於(yu)不(bu)斷(duan)變(bian)化(hua)犬(quan)態(tai)下(xia)這(zhe)蒸(zheng)汽(qi)的(de)密(mi)度(du)也(ye)會(hui)發(fa)生(sheng)變(bian)化(hua),從(cong)而(er)使(shi)蒸(zheng)氣(qi)的(de)流(liu)量(liang)發(fa)生(sheng)變(bian)化(hua)。這(zhe)就(jiu)需(xu)要(yao)在(zai)計(ji)量(liang)儀(yi)表(biao)要(yao)對(dui)這(zhe)種(zhong)變(bian)化(hua)情(qing)況(kuang)進(jin)行(xing)實(shi)時(shi)跟(gen)蹤(zong),以(yi)有(you)效(xiao)的(de)避(bi)免(mian)計(ji)量(liang)中(zhong)出(chu)現(xian)誤(wu)差(cha)。因(yin)此(ci)在(zai)當(dang)前(qian)蒸(zheng)汽(qi)計(ji)量(liang)時(shi),往(wang)往(wang)為(wei)了(le)能(neng)夠(gou)更(geng)好(hao)的(de)對(dui)蒸(zheng)汽(qi)壓(ya)力(li)和(he)溫(wen)度(du)的(de)變(bian)化(hua)進(jin)行(xing)跟(gen)蹤(zong),通(tong)常(chang)都(dou)會(hui)采(cai)用(yong)壓(ya)力(li)及(ji)溫(wen)度(du)傳(chuan)感(gan)器(qi),這(zhe)樣(yang)有(you)效(xiao)的(de)實(shi)現(xian)了(le)對(dui)密(mi)度(du)的(de)補(bu)償(chang)。
(三)蒸汽流量計量中的高溫高壓問題
火huo電dian內nei機ji組zu運yun行xing過guo程cheng中zhong所suo產chan生sheng的de蒸zheng汽qi上shang仍reng高gao溫wen高gao壓ya的de特te點dian,所suo以yi為wei了le能neng夠gou更geng好hao的de與yu這zhe一yi特te點dian相xiang適shi應ying,則ze需xu要yao選xuan擇ze適shi宜yi的de蒸zheng汽qi計ji量liang儀yi表biao,不bu僅jin需xu要yao具ju有you良liang好hao的de穩wen定ding性xing和he可ke靠kao性xing,而er且qie還hai要yao具ju有you較jiao好hao的de穩wen定ding性xing和he可ke靠kao性xing,而er且qie還hai要yao具ju有you較jiao好hao的de耐nai高gao溫wen和he高gao壓ya性xing能neng,所suo以yi在zai對dui蒸zheng汽qi計ji量liang過guo程cheng中zhong所suo使shi用yong的de儀yi表biao通tong常chang都dou會hui由you廠chang家jia進jin行xing專zhuan門men的de設she計ji和he製zhi造zao,而er且qie還hai要yao留liu有you較jiao大da的de裕yu度du,以yi確que保bao能neng夠gou準zhun確que對dui高gao溫wen、高壓蒸汽進行計量。
二、影響蒸汽準確計量的因素
(一)蒸汽流量的變化
在zai進jin行xing流liu量liang計ji選xuan擇ze是shi,需xu要yao確que保bao其qi能neng夠gou將jiang整zheng個ge工gong況kuang下xia或huo需xu要yao求qiu範fan圍wei內nei的de蒸zheng汽qi流liu量liang進jin行xing準zhun確que的de表biao示shi出chu來lai,這zhe就jiu需xu要yao流liu量liang計ji需xu要yao從cong極ji端duan的de低di負fu荷he至zhi最zui大da負fu荷he整zheng個ge範fan圍wei內nei的de流liu量liang都dou要yao準zhun確que進jin行xing測ce量liang。所suo以yi需xu要yao所suo選xuan擇ze的de流liu量liang計ji要yao具ju有you較jiao多duo的de量liang程cheng比bi。但dan量liang程cheng比bi通tong常chang情qing況kuang下xia都dou是shi針zhen對dui於yu實shi際ji流liu速su來lai講jiang的de,而er在zai流liu動dong速su度du較jiao大da時shi,係xi統tong會hui有you衝chong蝕shi和he噪zao音yin產chan生sheng,而er且qie不bu同tong流liu量liang計ji允yun許xu的de最zui低di流liu速su也ye有you所suo差cha異yi的de,因yin此ci在zai一yi些xie流liu量liang變bian化hua較jiao大da的de係xi統tong進jin行xing流liu量liang計ji量liang時shi,很hen容rong易yi在zai低di流liu速su時shi不bu能neng準zhun確que對dui流liu量liang進jin行xing計ji量liang。
(二) 蒸汽壓力和溫度變化引起密度變化
在(zai)對(dui)飽(bao)和(he)蒸(zheng)汽(qi)和(he)過(guo)熱(re)蒸(zheng)汽(qi)進(jin)行(xing)計(ji)量(liang),通(tong)常(chang)都(dou)是(shi)利(li)用(yong)質(zhi)量(liang)流(liu)量(liang),這(zhe)就(jiu)對(dui)蒸(zheng)汽(qi)密(mi)度(du)具(ju)有(you)十(shi)分(fen)密(mi)切(qie)的(de)叛(pan)亂(luan),而(er)蒸(zheng)汽(qi)密(mi)度(du)又(you)直(zhi)接(jie)接(jie)受(shou)到(dao)蒸(zheng)汽(qi)溫(wen)度(du)和(he)壓(ya)力(li)的(de)影(ying)響(xiang)。所(suo)以(yi)在(zai)進(jin)行(xing)蒸(zheng)汽(qi)計(ji)量(liang)時(shi),一(yi)旦(dan)壓(ya)力(li)和(he)溫(wen)度(du)發(fa)生(sheng)變(bian)化(hua),則(ze)蒸(zheng)汽(qi)密(mi)度(du)也(ye)會(hui)發(fa)生(sheng)改(gai)變(bian),而(er)蒸(zheng)汽(qi)質(zhi)量(liang)流(liu)量(liang)也(ye)會(hui)隨(sui)之(zhi)變(bian)化(hua)。這(zhe)就(jiu)需(xu)要(yao)流(liu)量(liang)計(ji)量(liang)儀(yi)表(biao)需(xu)要(yao)跟(gen)蹤(zong)變(bian)化(hua)情(qing)況(kuang),考(kao)慮(lv)的(de)蒸(zheng)汽(qi)壓(ya)力(li)和(he)溫(wen)度(du)的(de)變(bian)化(hua)進(jin)行(xing)密(mi)度(du)補(bu)償(chang),以(yi)避(bi)免(mian)計(ji)量(liang)誤(wu)差(cha)的(de)產(chan)生(sheng)。但(dan)在(zai)當(dang)前(qian)計(ji)量(liang)蒸(zheng)汽(qi)質(zhi)量(liang)流(liu)量(liang)的(de)大(da)部(bu)分(fen)流(liu)量(liang)計(ji)係(xi)統(tong)中(zhong)都(dou)沒(mei)有(you)補(bu)償(chang)這(zhe)一(yi)功(gong)能(neng),通(tong)常(chang)是(shi)在(zai)製(zhi)定(ding)壓(ya)力(li)和(he)溫(wen)度(du)下(xia)進(jin)行(xing)才(cai)能(neng)確(que)保(bao)計(ji)量(liang)的(de)準(zhun)確(que)性(xing)。即(ji)準(zhun)確(que)計(ji)量(liang)隻(zhi)能(neng)在(zai)壓(ya)力(li)、溫度和蒸汽密度保持不變的情況下才能實現。但一年四季溫度是處於不斷變化的情況下的,而且蒸汽係統負荷、係統參數等的變化也會導致壓力出現變化,不管這種變化是大還是小,都無法保證計量的準確性。
(三)差壓傳送誤差影響
1零點漂移、差壓變送器安(an)裝(zhuang)到(dao)現(xian)場(chang)投(tou)用(yong)是(shi),往(wang)往(wang)發(fa)現(xian)零(ling)位(wei)與(yu)出(chu)廠(chang)校(xiao)驗(yan)時(shi)的(de)零(ling)位(wei)不(bu)一(yi)致(zhi)。這(zhe)種(zhong)零(ling)位(wei)輸(shu)出(chu)偏(pian)離(li)稱(cheng)為(wei)靜(jing)壓(ya)誤(wu)差(cha)。其(qi)調(tiao)整(zheng)方(fang)法(fa)是(shi)向(xiang)正(zheng)負(fu)壓(ya)室(shi)通(tong)入(ru)相(xiang)同(tong)的(de)靜(jing)壓(ya),將(jiang)三(san)閥(fa)組(zu)的(de)高(gao)低(di)壓(ya)閥(fa)中(zhong)一(yi)個(ge)打(da)開(kai),另(ling)一(yi)個(ge)關(guan)閉(bi),將(jiang)平(ping)衡(heng)閥(fa)打(da)開(kai),如(ru)果(guo)懷(huai)疑(yi)正(zheng)負(fu)壓(ya)室(shi)內(nei)尚(shang)未(wei)充(chong)滿(man)被(bei)測(ce)介(jie)質(zhi),則(ze)可(ke)通(tong)過(guo)正(zheng)負(fu)壓(ya)室(shi)上(shang)的(de)泄(xie)壓(ya)閥(fa)排(pai)盡(jin)積(ji)氣(qi)或(huo)積(ji)液(ye),然(ran)後(hou)再(zai)檢(jian)查(zha)變(bian)送(song)器(qi)輸(shu)出(chu)。
2引壓管不止不合理。引壓管線應保證合理的坡度使管內可能出現 的de氣qi泡pao較jiao快kuai地di伸shen到dao母mu管guan內nei,管guan內nei出chu現xian的de雜za質zhi等deng較jiao快kuai地di沉chen到dao排pai汙wu閥fa。引yin壓ya管guan線xian應ying定ding期qi檢jian查zha維wei護hu,確que保bao無wu泄xie漏lou無wu堵du塞sai。引yin壓ya管guan的de內nei徑jing與yu被bei測ce流liu體ti的de性xing質zhi和he引yin壓ya管guan總zong長chang度du有you關guan。為wei了le避bi免mian正zheng負fu壓ya引yin壓ya管guan內nei介jie質zhi溫wen度du不bu一yi致zhi,導dao致zhi密mi度du出chu現xian差cha異yi而er引yin起qi傳chuan送song失shi真zhen,則ze正zheng負fu引yin壓ya管guan應ying盡jin量liang靠kao近jin布bu置zhi。當dang用yong於yu室shi外wai或huo嚴yan寒han地di區qu是shi,引yin壓ya管guan中zhong的de液ye體ti可ke能neng會hui結jie冰bing,因yin此ci,需xu要yao伴ban熱re保bao溫wen,但dan應ying避bi免mian將jiang伴ban熱re管guan直zhi接jie繞rao在zai引yin壓ya管guan上shang,導dao致zhi介jie質zhi部bu分fen汽qi化hua,出chu現xian虛xu假jia誤wu差cha。
3管道震動。渦街流量計等deng對dui機ji械xie震zhen動dong比bi較jiao敏min感gan的de流liu量liang計ji,在zai安an裝zhuang過guo程cheng中zhong除chu了le盡jin量liang滿man足zu前qian後hou直zhi管guan段duan要yao求qiu外wai,還hai應ying該gai注zhu意yi對dui流liu量liang計ji先xian後hou管guan道dao作zuo可ke靠kao支zhi撐cheng設she計ji。外wai來lai震zhen動dong會hui使shi渦wo街jie流liu量liang計ji產chan生sheng測ce量liang誤wu差cha,甚shen至zhi不bu能neng正zheng常chang工gong作zuo,如ru果guo管guan道dao振zhen動dong不bu可ke避bi免mian,應ying采cai用yong抗kang幹gan擾rao能neng力li強qiang的de差cha壓ya式shi流liu量liang計ji。
三、提高蒸汽流量計量的準確性措施
(一)正確選擇蒸汽流量計
選xuan好hao量liang程cheng,量liang程cheng的de測ce定ding範fan圍wei對dui計ji量liang的de影ying響xiang較jiao大da,傳chuan感gan器qi的de測ce程cheng範fan圍wei既ji能neng適shi應ying高gao峰feng時shi期qi的de最zui大da流liu量liang,又you能neng適shi應ying低di峰feng最zui小xiao流liu量liang,一yi般ban安an裝zhuang時shi要yao選xuan擇ze量liang程cheng比bi大da的de流liu量liang計ji,或huo者zhe是shi將jiang多duo個ge測ce量liang連lian接jie使shi用yong,滿man足zu工gong程cheng的de使shi用yong條tiao件jian。選xuan擇ze好hao安an裝zhuang的de流liu量liang計ji後hou就jiu要yao考kao慮lv管guan道dao大da小xiao、輸(shu)出(chu)形(xing)式(shi)等(deng)對(dui)測(ce)定(ding)儀(yi)器(qi)的(de)影(ying)響(xiang),如(ru)果(guo)選(xuan)用(yong)節(jie)流(liu)式(shi)測(ce)定(ding)計(ji)要(yao)按(an)設(she)計(ji)要(yao)求(qiu),進(jin)行(xing)管(guan)道(dao)粗(cu)細(xi)的(de)選(xuan)擇(ze),這(zhe)樣(yang)就(jiu)能(neng)提(ti)高(gao)測(ce)定(ding)準(zhun)確(que)性(xing),而(er)渦(wo)街(jie)測(ce)定(ding)儀(yi)在(zai)輸(shu)出(chu)時(shi)要(yao)選(xuan)擇(ze)脈(mai)衝(chong)式(shi)輸(shu)出(chu),可(ke)以(yi)防(fang)止(zhi)輸(shu)送(song)中(zhong)的(de)附(fu)加(jia)誤(wu)差(cha)。
(二)合理安置蒸汽流量計
bukejiangyiqianzhizaiguandaoweizhidezuidibuwei,anzhiweizhideshangxiayaoyoumanzuchangdudezhiguanduan。yinyaguanshezhidechangduheneibizhijingyaoyouyidingdefanwei,zheyangdefanweibuyidusaiqieliyuliuliangjijinxingjiliang。zhengfuyinyaguanyaofangzhiyinjijiehuojulideyuanyindaozhiwendubianhuachayida,erchanshengjiliangwucha。biyaoanzhuanglengningqi,lengningqideanzhuangweizhiyaoyuzhengqidezhengfuyinyaguanyouxiangtongdedenggaomian,qirongjiyaozugouda。
(三)運行中要嚴格安裝規範進行操作,並定期檢查維護
shouxian,kaishiyunxingshiyaozhengquecaozuogezhongyiqishunxu。xianjianzhalengningqiyijixiangyingdedaoyaguanneishifouchongmanshui,daoyaguanyugefamenshifouyouxielouxianxiang,ranhouzaiyizhaoyunxingliuchangjinxingtouyun。kaiqishunxu:打開平衡閥;打開負壓閥,開啟過程中,要注意力度的掌控,儀表進行緩慢開啟;打da開kai正zheng壓ya閥fa。開kai啟qi一yi定ding時shi間jian後hou要yao同tong時shi關guan閉bi正zheng負fu兩liang個ge閥fa門men。檢jian查zha冷leng凝ning器qi內nei的de冷leng凝ning水shui是shi否fou達da到dao兩liang邊bian平ping衡heng,若ruo滿man足zu要yao求qiu則ze要yao對dui差cha壓ya束shu送song錢qian進jin行xing調tiao整zheng,使shi其qi靜jing壓ya處chu在zai規gui範fan要yao求qiu內nei。冷leng凝ning器qi中zhong水shui麵mian若ruo沒mei有you相xiang齊qi,會hui致zhi使shi調tiao節jie後hou的de差cha壓ya輸shu送song器qi中zhong仍reng然ran存cun在zai一yi定ding的de靜jing壓ya偏pian差cha。再zai一yi次ci打da開kai正zheng負fu兩liang個ge閥fa門men。閉bi合he平ping和he閥fa門men,並bing啟qi動dong計ji量liang表biao。其qi次ci,在zai計ji量liang儀yi器qi進jin行xing運yun轉zhuan的de過guo程cheng中zhong,要yao對dui儀yi器qi進jin行xing定ding期qi檢jian查zha。
四、結束語
在zai火huo電dian廠chang蒸zheng汽qi流liu量liang計ji量liang過guo程cheng中zhong需xu要yao認ren真zhen對dui待dai每mei一yi個ge細xi小xiao的de環huan節jie,充chong分fen利li用yong先xian進jin和he科ke學xue的de技ji術shu和he儀yi器qi,確que保bao計ji量liang準zhun確que性xing,日ri常chang工gong作zuo重zhong要yao加jia強qiang對dui計ji量liang儀yi器qi的de檢jian查zha力li度du,確que保bao計ji量liang儀yi器qi各ge項xiang性xing能neng的de穩wen定ding性xing和he可ke靠kao性xing,從cong而er更geng好hao的de實shi現xian對dui蒸zheng汽qi流liu量liang計ji的de計ji量liang,實shi現xian電dian廠chang節jie能neng降jiang耗hao的de目mu標biao。
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