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1 概述

在自動控制系統中,調節閥是其常用的執行器。控制過程是否平穩取決于調節閥能否準確動作,使過程控制體現為物料能量和流量的精確變化。所以,要根據不同的需要選擇不同的調節閥。選擇恰當的調節閥是管路設計的主要問題,也是保證調節系統安全和平穩運行的關鍵。

2 調節閥的組成

diaojiefayouzhixingjigouhediaojiejigouzucheng,jieshoudiaojieqihuojisuanjidekongzhixinhao,yonglaigaibianbeikongjiezhideliuliang,shibeidiaocanshuweichizaisuoyaoqiudefanweinei,congerdadaoguochengkongzhidezidonghua。

2.1 執行機構

zhixingjigouanzhaoqudongxingshifenweiqidong、diandongheyedong3zhong。qidongzhixingjigoujuyoujiegoujiandan,dongzuokekao,xingnengwending,jiagedi,weihufangbian,fanghuofangbaodengyoudian,zaixuduokongzhixitongzhonghuodeleguangfandiyingyong。diandongzhixingjigousuiranbuliyufanghuofangbao,danqiqudongdianyuanfangbiankequ,qiexinhaochuanshusudukuai,bianyuyuanjulichuanshu,tijixiao,dongzuokekao,weixiufangbian,jiagebianyi。yedongzhixingqidetuilizuida,diaojiejingdugao,dongzuosudukuai,yunxingpingwen,danyouyushebeitijida,gongyifuza,suoyimuqianshiyongbuduo。

執行機構不論是何種類型,其輸出力都是用于克服負荷的有效力(主要是指不平衡力和不平衡力矩、摩擦力、密封力及重力等有關力的作用)。因此,為了使調節閥正常工作,配用的執行機構要能產生足夠的輸出力來克服各種阻力,保證高度密封和閥門的開啟。對執行機構輸出力確定后。應根據工藝使用環境要求,選擇相應的執行機構。例如,對于現場有防爆要求時,應選用氣動執行機構,且接線盒為防爆型。如果沒有防爆要求,則氣動或電動執行機構都可選用,但從節能方面考慮,應盡量選用電動執行機構。對于要求調節精度高,動作速度快和運行平穩的工況,應選用液動執行機構。

zonghegeleizhixingqidetedian,zidongkongzhixitongpubiancaiyongdiandongzhixingjigou。rujiegoujiandan、tijixiaode zaz zhixingchengleiji zaj jiaoxingchenglei,3610l(r) xingdianzishijiskdxingduozhuandiandongzhixingjigoudeng。geleizhixingjigoujinguanzaijiegoushangbuwanquanxiangtong,danjibenjiegoudoubaokuofangdaqi、kenidianji、jiansuzhuangzhi、tuilijigou、jixiexianweizujian、danxinglianzhouqiheweizhifankuidengbujian(tu 1)。

電動執行機構的方框圖
圖1 電動執行機構的方框圖

diandongzhixingjigouyibanxuyaoyusifufangdaqipeitao,jieshoudiaojieqidexinhao,gaixinhaojingguosifufangdaqifangdahouzhuanhuanweisanweijidianxinhao,kongzhikenidianjizhengzhuanhuofanzhuan,daidongdiaojiejigou,shifakaiqihuoguanbi。

2.2 調節機構

調節閥門是調節閥的調節機構,它根據控制信號的要求而改變閥門開度的大小來調節流量,是一個局部阻力可以變化的節流元件。調節閥門主要由上下閥蓋、閥體、閥瓣、閥座、填料及壓板等部件組成。在自動控制系統中,閥門主要的調節介質為水和蒸汽等。在壓力比較低,使用情況單一的情況下,常用的調節閥有直通調節閥、三通調節閥和蝶閥等。

直通閥有直通單座閥雙座閥之分。單座閥結構簡單,價格低廉,關閉時泄漏量小,但由于閥座前后存在的壓差對閥瓣產生的不平衡力較大,所以適用于低壓差的場合,例如供水管或回水管中。雙座閥有兩個閥瓣閥座,在其關閉狀態時,兩個閥瓣的受力可部分抵消,閥瓣所受的不平衡力小,但是由于熱脹冷縮效應,其同時關閉性較差,造價也較高,只適用于閥前后壓差較高但密閉要求不高的場合,例如供水或回水之間的壓差旁通閥。

santongfayousangechurukouyuguandaoxianglian,zongjinshuiliangjiaohengding,shiyongyudingshuiliangxitongzhong,bingyaoqiuyougudingdeanzhuangfangxiang,buyifanzhuang,bushiyuwenchajiaodachanghe。santongdiaojiefayouheliufayufenliufazhifen。heliufashijianglaizilianggerukoudeliutihunhezhiyigechukou。fenliufazeshijiangyigerukoudeliutifenbieyoulianggekousongchu。

diefajiegoujiaojiandan,youfati、diebanzhoujizhoufengdengbufenzucheng,qixingchengwei 0°~90°。diefayouliangweishikongzhihebilikongzhi 2 zhongfangshi。diefadetedianshizulisunshixiao,tijixiao,zhiliangqing,anzhuangfangbian,bingqiekaiqifamenheguanbifamendeyunxuyachajiaoda,danqidiaojiexingnengheguanfamibixingnengjiaocha,tongchangyongyuyachajiaodadandiaojiexingnengyaoqiubugaodechangsuo。chuyongzuoliangtongfawai,huankeyiyonglianggediefazuhe,wanchengsantongfadegongneng。zaizidongkongzhixitongzhong,kai/guanxingdiandongdiefachangyongyulengshuihereshuixitongzhong,zuoweishuiludeliantongheguanduankongzhi。

3 性能

3.1 工作原理

genjuliutilixuekezhi,diaojiefashiyigejubuzulikeyibianhuadejieliuyuanjian。duibukeyasuoliuti,diaojiefadeliuliangkebiaoshiwei:

調節閥流量公式

式中:Q–調節閥某一開度的流量,mm3/s
P1–調節閥進口壓力,MPa
P2–調節閥出口壓力,MPa
A–節流截面積,mm2
ξ–調節閥阻力系數
ρ–流體密度,kg/mm3

youshi(1)kezhi,dang a yiding,δp=p1-p2 yehengdingshi,tongguofadeliuliang q suizulixishu ξ bianhua,jizulixishu ξ yuda,liuliangyuxiao。erzulixishu ξ zeyufadejiegouhekaiduyouguan。suoyidiaojieqishuchuxinhaokongzhifamendekaihuoguan,kegaibianfadezulixishu,congergaibianbeidiaojiezhideliuliang。

3.2 流量特性

diaojiefadeliuliangtexingshizhibeidiaojiezhiliuguodiaojiefadexiangduiliuliangyudiaojiefadexiangduikaiduzhijiandeguanxi。qishuxuebiaodashiwei:

調節閥的相對流量與調節閥的相對開度之間的關系

式中:Qmax–調節閥全開時流量,mm3/s
L—-調節閥某一開度的行程,mm
Lmax–調節閥全開時行程,mm

diaojiefadeliuliangtexingbaokuolixiangliuliangtexinghegongzuoliuliangtexing。lixiangliuliangtexingshizhizaidiaojiefajinchukouyachagudingbubianqingkuangxiadeliuliangtexing,youzhixian、dengbaifenbi、paowuxianjikuaikai 4 zhongtexing(biao1)。

表1 調節閥 4 種理想流量特性
流量特性 性質 特點
直線 調節閥的相對流量與相對開度呈直線關系,即單位相對行程變化引起的相對流量變化是一個常數 ① 小開度時,流量變化大,而大開度時流量變化小
② 小負荷時,調節性能過于靈敏而產生振蕩,大負荷時調節遲緩而不及時
③ 適應能力較差
等百分比 單位相對行程的變化引起的相對流量變化與此點的相對流量成正比 ① 單位行程變化引起流量變化的百分率是相等的
② 在全行程范圍內工作都較平穩,尤其在大開度時,放大倍數也大。工作更為靈敏有效
③ 應用廣泛,適應性強
拋物線 特性介于直線特性和等百分比特性之間,使用上常以等百分比特性代之 ① 特性介于直線特性與等百分比特性之間
② 調節性能較理想但閥瓣加工較困難
快開 在閥行程較小時,流量就有比較大的增加,很快達最大 ① 在小開度時流量已很大,隨著行程的增大,流量很快達到最大
② 一般用于雙位調節和程序控制

zaishijixitongzhong,famenliangcedeyalijiangbingbushihengdingde,shiqifashengbianhuadeyuanyinzhuyaoyoulianggefangmian。yifangmian,youyubengdetexing,dangxitongliuliangjianxiaoshiyoubengchanshengdexitongyalizengjia。lingyifangmian,dangliuliangjianxiaoshi,panguanshangdezuliyejianxiao,daozhijiaodadebengyajiayufamen。yincidiaojiefajinchukoudeyachatongchangshibianhuade,zaizhezhongqingkuangxia,diaojiefaxiangduiliuliangyuxiangduikaiduzhijiandeguanxi。chengweigongzuoliuliangtexing。jutikefenweichuanlianguandaoshidegongzuoliuliangtexinghebinglianguandaoshidegongzuoliuliangtexing。

(1)chuanlianguandaoshidegongzuoliuliangtexing

diaojiefayuguandaochuanlianshi,yindiaojiefakaidudebianhuahuiyinqiliuliangdebianhua,youliutilixuelilunkezhi,guandaodezulisunshiyuliuliangchengpingfangguanxi。diaojiefayidandongzuo,liuliangzegaibian,xitongzuliyexiangyinggaibian,yincidiaojiefayajiangyexiangyingbianhua。chuanlianguandaoshidegongzuoliuliangtexingyuyajiangfenpeibiyouguan。fashangyajiangyuexiao,diaojiefaquankailiuliangxiangyingjianxiao,shilixiangdezhixiantexingjibianweikuaikaitexing,lixiangdedengbaifenbitexingjibianweizhixiantexing。zaishijishiyongzhong,dangdiaojiefaxuandeguodahuoshengchanchuyufeimanfuhezhuangtaishi,diaojiefazegongzuozaixiaokaidu,youshiweileshidiaojiefayouyidingdekaidu,erjiangfamenkaidudiaoxiaoyizengjiaguandaozuli,shiliuguodiaojiefadeliuliangjiangdi,shijishangjiushishiyajiangfenpeibizhixiajiang,shiliuliangtexingjibian,ehualediaojiezhiliang。

(2)binglianguandaoshidegongzuoliuliangtexing

diaojiefayuguandaobinglianshi,yibanyoufazhiluhepangtongguanzhiluzucheng,diaojiefaanzhuangzaifazhiluguanlushang。diaojiefazaibinglianguandaoshang,zaixitongzuliyidingshi,diaojiefaquankailiuliangyuzongguanzuidaliuliangzhibisuizhubinglianguandaodepanglufazhubudakaierjianshao。cishi,jinguandiaojiefabenshendeliuliangtexingwubianhua,danxitongdekediaofanweidadasuoxiao,diaojiefazaigongzuoguochengzhongsuonengkongzhideliuliangbianhuafanweiyedadajianxiao,shenzhiqibudaodiaojiezuoyong。yaoshidiaojiefayoujiaohaodediaojiexingneng,yibanrenweipangluliuliangzuiduobuchaoguozongliuliangde 20%。

4 調節閥的選擇

4.1 流量特性選擇

liuliangtexingdexuanzefangfayouliangzhong,yizhongshitongguoshuxuejisuandefenxifa,lingyizhongshizaishijigongchengzhongzongjiedejingyanfa。youyufenxifajifuzayoufeishi,suoyiyibangongchengshangdoucaiyongjingyanfa。jutilaishuo,yinggaicongdiaojiezhiliang、gongkuangtiaojian、fuhejitexingjigefangmiankaolv。

(1)genjuzidongdiaojiexitongdediaojiezhiliang

genjuzidongkongzhiyuanlizhongdetexingbuchangyuanli,weileshixitongbaochilianghaodediaojiezhiliang,xiwangkaihuanzongfangdaxishuyugehuanjiefangdaxishuzhijibaochichangshu。zheyang,shidangxuanzefadetexing,yifadefangdaxishubianhualaibuchangduixiangfangdaxishudebianhua,congershixitongdezongfangdaxishubaochibubian。

(2)genjuguandaoxitongyajiangbianhuaqingkuang

diaojiefadeyajiangbi s dingyiweigaidiaojiefakekongzhidezuidaliuliangsuoduiyingfamenjinchukouchaya δp1m hexitongchaya δp zhibi:

調節閥的壓降比計算公式

diaojiefaliuliangtexingyuyajiangbisyoumiqiedeguanxi(biao2)。

表2 管道系統壓降選擇調節閥特性
管道系統壓降比 S 1~0.6 0.6~0.3 0.3~0
實際工作流量特性 直線 等百分比 直線 等百分比 調節不適宜
所選流量特性 直線 等百分比 等百分比 等百分比

(3)genjufuhebianhua

zhixianfazaixiaokaidushiliuliangbianhuada,diaojieguoyulingmin,yizhendang。zaidakaidushi,diaojiezuoyongyouxiandeweiruo,zaochengdiaojiebujishi,bulingmin。yincizaiyajiangbisjiaoxiao,fuhebianhuadadechanghebuyicaiyongzhixianfa。dengbaifenbifazaijiejinguanbishigongzuohuanhepingwen,erjiejinquankaizhuangtaishi,fangdaxishuda,gongzuolingminyouxiao,yincitashiyongyufuhebianhuafududadechanghe。kuaikaitexingfazaixingchengjiaoxiaoshi,liuliangjiujiaoda,suizhuxingchengdezengda,liulianghenkuaidadaozuida,tayibanyongyushuangweidiaojiehechengxukongzhidechanghe。

(4)genjudiaojieduixiangdetexing

yibanyouzipinghengnenglidediaojieduixiangdoukexuanzedengbaifenbiliuliangtexingdediaojiefa,bujuyouzipinghengnenglidediaojieduixiangzexuanzezhixianliuliangtexingdediaojiefa。

4.2 口徑選擇

調節閥口徑是根據工藝要求的流通能力確定的,要根據提供的工藝條件計算出調節閥的流通能力,再依據其流通能力選擇調節閥的口徑。流通能力是指當調節閥全開,閥兩端壓差為 9.81×104Pa,流體的密度為 1g/cm3 時,每小時流經調節閥的流量值,該值以 m3/h 或 kg/h 為單位。調節閥的流通能力是合理選擇閥門及閥門口徑的一個重要參數,通過對調節閥流通能力的計算,對比廠家提供的技術參數確定閥門口徑的大小。對于自動控制系統來說,水是流經調節閥的常見的介質之一,所以以水為例介紹調節閥的流通能力 C:

調節閥的流通能力計算公式

shijigongchengzhong,famenkoujingshifenjide,c zhitongchangyebushilianxuzhi(gongshijisuande c zhishilianxude)。butongchangshangdetongleixingchanpinyoubutongde c zhiyukoujingduiyingbiao。zaijisuanchuqiwangde c zhihou,jiukeyichayueshengchanshangdexiangyingchanpinshujubiaolaijuedingsuoxudefamenkoujing。xuanqufamenkoujingdeyuanzeyingjinkenengjiejinhuodayujisuanjieguo,buyingxiaoyujisuanjieguo。

4.3 選用注意事項

(1)diaojiefazhijieanzhaojieguanguanjingxuanqushibuhelide。famendediaojiepinzhiyujieguanliusuhuoguanjingmeiyouguanxi,famendediaojiepinzhijinyushuidezulijiliuliangyouguan。yijiyidanxitongshebeiquedingzhihou,lilunshangshihegaixitongdefamenzhiyouyizhonglixiangdekoujing,erbuhuichuxianduozhongxuanze。

(2)diaojiefakoujingbunengguoxiao。xuanzedefamenkoujingguoxiao,yifangmianhuizengjiaxitongdezuli,shenzhihuichuxianfamenkoujing 100% kaiqishi,xitongrengwufadadaoshedingderongliangyaoqiu,daozhiyanzhonghouguo。lingyifangmianfamenjiangxuyaotongguoxitongtigongjiaodadeyachayiweichizugoudeliuliang,jiazhongbengdefuhe,famenyishousunhai,duifamendeshoumingyingxianghenda。

(3)diaojiefakoujingbunengguoda。xuanzedefamenkoujingguoda,bujinzengjiagongchengchengben,erqiehuanhuiyinqifamenjingchangyunxingzaidibaifenbifanweinei,yinqidiaojiejingdujiangdi,shikongzhixingnengbiancha,erqieyishixitongshouchongjihezhendang。

(4)weilebaozhengxitongkongzhipinzhi,zuihaodefangfashizaixitongyunxudefanweineixuanzenenghuodejiaodayalijiangdefamenkoujing,shifamenzaiyunzhuanguochengzhongyalijiangdebianhuazhijinkenengxiao。famenquankaizhuangtaixiadeyalijiangzhanquanbengyabaifenbiyuegao,zefamenyalijiangxiangduibianhuazhiyuexiao,famendeanzhuangtexingjiuyuejiejinqineizaitexing。

(5)kongzhixitongzhongdiaojiefayingjinkenenggongzuoyuhengdingdeyalijiangtiaojianxia,yinweifamenshifoupipeipanguanyilaiyutadeneizaitexingheliuliangyinzi,erzhexiefamencanshuqujueyuhengdingdefamenyalijiang。

5 結語

shejidiaojiefashi,yaoqiuduidiaojiefadezucheng、fenleihetexingyouyigeqingchuderenshi,bingzaicijichushangzhangwozhengquedexuanzefangfa。erqie,duiyuyigeshijixitongpeizhidiaojiefashi,huanxuyaoduizhenggeguanxihuanlujinxingxiangjindefenxi,zonghekaolvgezhongyinsu。zhiyouzheyang,cainengzhengquedixuanzediaojiefa,baozhengdiaojiexitongdekongzhizhiliang。


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下一篇:控制回路中氣動調節閥的選用
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