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- 電加熱導熱油爐常見的事故隱患及處理措施
- 發布日期:2019年12月11 點擊次數:78 所屬分類:常見問題
1、導熱(re)油(you)品質(zhi)下降的隱患
因生產(chan)工藝操作(zuo)管理(li)不(bu)善而導(dao)致的導(dao)熱(re)(re)(re)油(you)(you)品(pin)質(zhi)過早變質(zhi),是電加(jia)熱(re)(re)(re)導(dao)熱(re)(re)(re)油(you)(you)爐最(zui)容易發(fa)生的問題之(zhi)一(yi),有些導(dao)熱(re)(re)(re)油(you)(you)僅僅使(shi)用(yong)一(yi)兩年(nian)(nian),性能指標(biao)(biao)就嚴重劣化。而長期運行劣質(zhi)的導(dao)熱(re)(re)(re)油(you)(you),受熱(re)(re)(re)面(mian)管壁(bi)積碳(tan)不(bu)斷(duan)增(zeng)(zeng)加(jia),管內徑縮小使(shi)導(dao)熱(re)(re)(re)油(you)(you)流量(liang)(liang)不(bu)斷(duan)降低(di),循環泵(beng)阻力逐步增(zeng)(zeng)大(da)(da),傳(chuan)熱(re)(re)(re)效率持續降低(di),進(jin)而導(dao)致爐管內結焦、堵塞,最(zui)終發(fa)生過燒、變形、爆(bao)管等惡性事(shi)故。 造(zao)成導(dao)熱(re)(re)(re)油(you)(you)品(pin)質(zhi)下降的原因之(zhi)一(yi)是局部過熱(re)(re)(re)發(fa)生熱(re)(re)(re)裂解(jie),二是導(dao)熱(re)(re)(re)油(you)(you)氧(yang)(yang)化。導(dao)熱(re)(re)(re)油(you)(you)超過其規定(ding)的最(zui)高使(shi)用(yong)溫(wen)度便(bian)會局部過熱(re)(re)(re),產(chan)生熱(re)(re)(re)分(fen)解(jie)和縮聚(ju),析出殘碳(tan),閃(shan)點下降,顏色(se)變深,黏(nian)度增(zeng)(zeng)大(da)(da),傳(chuan)熱(re)(re)(re)效率下降,結焦老化。導(dao)熱(re)(re)(re)油(you)(you)與(yu)空氣中的氧(yang)(yang)氣接觸(chu)發(fa)生氧(yang)(yang)化反應,生成有機(ji)酸(suan)并縮聚(ju)成膠泥(ni),使(shi)黏(nian)度增(zeng)(zeng)加(jia),不(bu)僅降低(di)介(jie)質(zhi)的使(shi)用(yong)壽(shou)命,而且造(zao)成系統酸(suan)性腐蝕。 目前國內各導(dao)熱(re)(re)(re)油(you)(you)廠制定(ding)的質(zhi)量(liang)(liang)標(biao)(biao)準各自(zi)不(bu)同,生產(chan)的導(dao)熱(re)(re)(re)油(you)(you)質(zhi)量(liang)(liang)也差異較大(da)(da),對于使(shi)用(yong)中的導(dao)熱(re)(re)(re)油(you)(you),《有機(ji)熱(re)(re)(re)載體爐安全技術(shu)監察規程》規定(ding)每(mei)年(nian)(nian)對運動粘度、閃(shan)點、殘碳(tan)、酸(suan)值至少檢測(ce)一(yi)次。
2、自動控制(zhi)系(xi)統失效的隱(yin)患
當前,國內導(dao)熱(re)(re)油(you)電(dian)加熱(re)(re)器工藝(yi)的(de)現狀是導(dao)熱(re)(re)油(you)控(kong)制(zhi)(zhi)系(xi)統以可編程序控(kong)制(zhi)(zhi)器控(kong)制(zhi)(zhi)PLC為控(kong)制(zhi)(zhi)核心,對一定溫度(du)的(de)導(dao)熱(re)(re)油(you),在(zai)循環(huan)泵的(de)工作壓力下從加熱(re)(re)器的(de)進口進入,導(dao)熱(re)(re)油(you)通過(guo)加熱(re)(re)器發熱(re)(re)腔(qiang)使溫度(du)逐(zhu)步升高,然(ran)后從出口流出,從而(er)導(dao)熱(re)(re)油(you)達(da)到(dao)(dao)所需的(de)工藝(yi)溫度(du),使得(de)設(she)備的(de)自(zi)動化程度(du)得(de)到(dao)(dao)進一步提高。
在控制系(xi)(xi)統(tong)中(zhong)導熱(re)(re)(re)油經過齒輪(lun)泵(beng)送(song)入整個(ge)系(xi)(xi)統(tong)中(zhong),當設(she)定好的磁性翻柱(zhu)式(shi)液位控制器(qi)到達指定液位時(shi),齒輪(lun)泵(beng)自(zi)動(dong)關閉,這時(shi)啟動(dong)循環(huan)泵(beng)和電加(jia)熱(re)(re)(re)器(qi)開始(shi)加(jia)熱(re)(re)(re),當出口油溫達到設(she)定值時(shi),進入用戶(hu)系(xi)(xi)統(tong)循環(huan),經設(she)備使(shi)用后的油再次進入裝置加(jia)熱(re)(re)(re),周而復始(shi),循環(huan)運轉,即為導熱(re)(re)(re)油的工作狀態。
這些自動控(kong)制系統是保證電加熱(re)導(dao)熱(re)油爐安(an)全運行(xing)的有效(xiao)關卡,而(er)往往就是這些關卡,在實(shi)際運行(xing)中常由于安(an)全意識的薄弱或(huo)經(jing)濟方(fang)面(mian)的原因而(er)失效(xiao)。
3、空(kong)氣(qi)和水分(fen)進入(ru)的隱患
在電加(jia)熱(re)導熱(re)油爐新加(jia)油、換油和維(wei)修(xiu)過程中(zhong)(zhong)易進(jin)入空(kong)(kong)氣(qi)和水(shui)分(fen),在加(jia)溫過程中(zhong)(zhong)這(zhe)些(xie)空(kong)(kong)氣(qi)膨脹、水(shui)分(fen)蒸(zheng)發,其(qi)體(ti)積(ji)的變(bian)化(hua)遠(yuan)遠(yuan)超過了(le)導熱(re)油自(zi)身(shen)熱(re)膨脹量,相對壓力為零時,水(shui)蒸(zheng)發時體(ti)積(ji)膨脹約(yue)是其(qi)原來的1600多(duo)倍,空(kong)(kong)氣(qi)在升溫270℃的情況下約(yue)膨脹5倍。這(zhe)些(xie)空(kong)(kong)氣(qi)和水(shui)分(fen)如果(guo)不(bu)能及時得到排(pai)放(fang),必將引起運行(xing)壓力提高,嚴(yan)(yan)重威脅系統(tong)(tong)安全。因此(ci),應嚴(yan)(yan)格控制導熱(re)油中(zhong)(zhong)的水(shui)分(fen)及其(qi)他組分(fen)。在加(jia)熱(re)啟(qi)動過程中(zhong)(zhong)要反復打(da)開排(pai)氣(qi)閥,以排(pai)凈系統(tong)(tong)中(zhong)(zhong)的空(kong)(kong)氣(qi)、水(shui)與導熱(re)油混合(he)蒸(zheng)汽,并注意控制導熱(re)油升溫速度。
4、 管道(dao)法蘭或(huo)閥門間的泄漏(lou)隱患
管道法(fa)蘭或(huo)閥門連接處(chu)(chu)是導(dao)(dao)熱(re)油系(xi)統最易(yi)發(fa)生泄(xie)漏的(de)部位,由于導(dao)(dao)熱(re)油具(ju)有(you)易(yi)滲(shen)透、易(yi)燃燒(shao)的(de)特性(xing),尤(you)其(qi)是對多孔(kong)材料制成的(de)保溫(wen)層(ceng)浸附(fu)性(xing)更(geng)強。如果導(dao)(dao)熱(re)油一旦(dan)發(fa)生泄(xie)漏而沒能及時(shi)發(fa)現,很容易(yi)引發(fa)火災(zai)。因此,必須(xu)定期檢查法(fa)蘭和(he)閥門連接處(chu)(chu)的(de)完好情況(kuang),如有(you)損壞應(ying)(ying)及時(shi)更(geng)換。從(cong)導(dao)(dao)熱(re)油爐停用(yong)到運行過程,由于溫(wen)度變化大,法(fa)蘭間易(yi)松動,常有(you)滲(shen)漏現象,這時(shi)應(ying)(ying)引起重視。管道系(xi)統中(zhong)所有(you)密封(feng)件應(ying)(ying)選用(yong)具(ju)有(you)良好密封(feng)性(xing)和(he)阻(zu)燃性(xing)的(de)柔性(xing)和(he)金屬纏繞制品(pin),切忌用(yong)含有(you)橡膠(jiao)成分的(de)密封(feng)件。保溫(wen)材料應(ying)(ying)采用(yong)空隙(xi)度小且不易(yi)受有(you)機熱(re)載(zai)體浸漬的(de)材料,以防(fang)有(you)機熱(re)載(zai)體泄(xie)漏后造(zao)成保溫(wen)層(ceng)著火。
5、電加熱棒結焦炭化的隱患
用電(dian)(dian)熱(re)(re)(re)棒(bang)(bang)(bang)加熱(re)(re)(re)導(dao)(dao)(dao)(dao)熱(re)(re)(re)油(you)(you)(you)時,電(dian)(dian)熱(re)(re)(re)棒(bang)(bang)(bang)表面(mian)(mian)(mian)(mian)會很快結(jie)焦(jiao)炭化,最終使(shi)電(dian)(dian)熱(re)(re)(re)捧(peng)燒毀,導(dao)(dao)(dao)(dao)熱(re)(re)(re)油(you)(you)(you)報(bao)廢。造成(cheng)嚴重積(ji)炭的(de)(de)(de)原因可(ke)(ke)(ke)通過(guo)傳熱(re)(re)(re)計(ji)(ji)(ji)算來(lai)分析:從市場(chang)上購來(lai)的(de)(de)(de)220V4kW電(dian)(dian)熱(re)(re)(re)棒(bang)(bang)(bang)表面(mian)(mian)(mian)(mian)積(ji)為(wei)0.125m2,在(zai)自然對流狀(zhuang)態(tai)下傳熱(re)(re)(re)系數(shu)K=67~114W/℃·m2,取大(da)值K=114W/℃·m2。根據(ju)Q=KF△t計(ji)(ji)(ji)算可(ke)(ke)(ke)知,電(dian)(dian)熱(re)(re)(re)棒(bang)(bang)(bang)要傳給(gei)導(dao)(dao)(dao)(dao)熱(re)(re)(re)油(you)(you)(you)4 kW熱(re)(re)(re)量(liang)(liang),棒(bang)(bang)(bang)表面(mian)(mian)(mian)(mian)與導(dao)(dao)(dao)(dao)熱(re)(re)(re)油(you)(you)(you)的(de)(de)(de)溫(wen)(wen)差必須大(da)于(yu)275℃。當(dang)導(dao)(dao)(dao)(dao)熱(re)(re)(re)油(you)(you)(you)平均溫(wen)(wen)度(du)為(wei)300℃時,棒(bang)(bang)(bang)表面(mian)(mian)(mian)(mian)溫(wen)(wen)度(du)必須達575℃。而最高允(yun)(yun)許(xu)使(shi)用溫(wen)(wen)度(du)為(wei)340℃的(de)(de)(de)導(dao)(dao)(dao)(dao)熱(re)(re)(re)油(you)(you)(you)在(zai)加熱(re)(re)(re)爐管(guan)中(zhong)的(de)(de)(de)允(yun)(yun)許(xu)膜(mo)溫(wen)(wen)(相當(dang)于(yu)這里(li)的(de)(de)(de)棒(bang)(bang)(bang)表面(mian)(mian)(mian)(mian)溫(wen)(wen)度(du))不得超過(guo)370℃。現在(zai)導(dao)(dao)(dao)(dao)熱(re)(re)(re)油(you)(you)(you)與575℃的(de)(de)(de)棒(bang)(bang)(bang)表面(mian)(mian)(mian)(mian)接(jie)(jie)觸,結(jie)焦(jiao)炭化肯定是(shi)嚴重的(de)(de)(de),導(dao)(dao)(dao)(dao)熱(re)(re)(re)油(you)(you)(you)的(de)(de)(de)壽命也很短。 防(fang)止在(zai)電(dian)(dian)熱(re)(re)(re)棒(bang)(bang)(bang)表面(mian)(mian)(mian)(mian)嚴重積(ji)炭的(de)(de)(de)途徑是(shi)增加電(dian)(dian)熱(re)(re)(re)棒(bang)(bang)(bang)的(de)(de)(de)表面(mian)(mian)(mian)(mian)積(ji),使(shi)棒(bang)(bang)(bang)表面(mian)(mian)(mian)(mian)熱(re)(re)(re)負荷限定在(zai)適當(dang)范圍內。通過(guo)計(ji)(ji)(ji)算將4kW 電(dian)(dian)熱(re)(re)(re)棒(bang)(bang)(bang)中(zhong)并聯(lian)(lian)的(de)(de)(de)兩根2kW 電(dian)(dian)阻絲改(gai)接(jie)(jie)成(cheng)串聯(lian)(lian),端(duan)電(dian)(dian)壓為(wei)220V 時,電(dian)(dian)阻絲的(de)(de)(de)總功率為(wei)1 kW。電(dian)(dian)熱(re)(re)(re)捧(peng)表面(mian)(mian)(mian)(mian)積(ji)仍為(wei)0.125m2,傳熱(re)(re)(re)所需溫(wen)(wen)差為(wei)69℃。同樣(yang),平均油(you)(you)(you)溫(wen)(wen)為(wei)300℃時, 電(dian)(dian)熱(re)(re)(re)棒(bang)(bang)(bang)表面(mian)(mian)(mian)(mian)溫(wen)(wen)度(du)為(wei)369℃即(ji)可(ke)(ke)(ke),將1 kW 熱(re)(re)(re)量(liang)(liang)傳給(gei)導(dao)(dao)(dao)(dao)熱(re)(re)(re)油(you)(you)(you)。369℃已(yi)接(jie)(jie)近導(dao)(dao)(dao)(dao)熱(re)(re)(re)油(you)(you)(you)允(yun)(yun)許(xu)的(de)(de)(de)膜(mo)溫(wen)(wen)370℃,有可(ke)(ke)(ke)能(neng)使(shi)結(jie)焦(jiao)問題得到緩解(jie)。最好的(de)(de)(de)解(jie)決方法(fa)是(shi)專(zhuan)門設計(ji)(ji)(ji)制造專(zhuan)用的(de)(de)(de)電(dian)(dian)熱(re)(re)(re)棒(bang)(bang)(bang),增大(da)表面(mian)(mian)(mian)(mian)積(ji),使(shi)捧(peng)表面(mian)(mian)(mian)(mian)溫(wen)(wen)度(du)低于(yu)導(dao)(dao)(dao)(dao)熱(re)(re)(re)油(you)(you)(you)的(de)(de)(de)允(yun)(yun)許(xu)液膜(mo)溫(wen)(wen)度(du)。
6、結語(yu)
總之,由于電(dian)加(jia)熱(re)導(dao)熱(re)油爐(lu)所使用的(de)導(dao)熱(re)油介(jie)質具有易(yi)滲(shen)漏、易(yi)燃燒的(de)特性(xing),若對(dui)其(qi)(qi)介(jie)質特殊性(xing)和操作安全性(xing)認識(shi)不夠,在(zai)運行中極易(yi)發(fa)生泄(xie)漏和火災、爆炸等(deng)事故(gu),而識(shi)別(bie)了其(qi)(qi)常見的(de)事故(gu)隱患并有針(zhen)對(dui)性(xing)地采取預防措(cuo)施即可大(da)大(da)降低(di)電(dian)加(jia)熱(re)導(dao)熱(re)油爐(lu)發(fa)生火災事故(gu)的(de)風險。
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