水(shui)環式真(zhen)空泵和干式真(zhen)空泵均屬(shu)于(yu)變容積真(zhen)空泵,是石油化工(gong)裝置中常用的(de)真(zhen)空泵型(xing)式。在實際工(gong)作環境下(xia),按照(zhao)不同工(gong)況,依據工(gong)作抽氣量、真(zhen)空度等要(yao)求,結合(he)真(zhen)空泵的(de)系統組成和機構(gou)復雜情況等,對干式真(zhen)空泵、水(shui)環式真(zhen)空泵進(jin)行合(he)理選型(xing),對清潔生產、節能降耗(hao)以及保障工(gong)藝過程順利進(jin)行有重要(yao)意義。
水環式真空泵
水環式真(zhen)空(kong)泵結構(gou)及工(gong)作原理如下(xia)。
葉(xie)(xie)輪(lun)(lun)偏心安裝在泵體內(nei)(nei),啟動時需向(xiang)泵內(nei)(nei)注入一(yi)定(ding)量的工(gong)作(zuo)液(ye)(ye)。葉(xie)(xie)輪(lun)(lun)旋轉時,工(gong)作(zuo)液(ye)(ye)在離心力的作(zuo)用下在泵體內(nei)(nei)壁(bi)形(xing)成(cheng)一(yi)個旋轉的封閉液(ye)(ye)環,液(ye)(ye)環下部內(nei)(nei)表面與(yu)輪(lun)(lun)轂相(xiang)切,上部內(nei)(nei)表面與(yu)葉(xie)(xie)片(pian)頂端(duan)接(jie)觸。輪(lun)(lun)轂與(yu)液(ye)(ye)環之間(jian)形(xing)成(cheng)1個月牙形(xing)空間(jian),該空間(jian)被(bei)葉(xie)(xie)輪(lun)(lun)葉(xie)(xie)片(pian)分(fen)成(cheng)若干體積(ji)不同的腔體。
吸(xi)氣過(guo)程(cheng)中,腔(qiang)體(ti)(ti)(ti)(ti)體(ti)(ti)(ti)(ti)積由小(xiao)變大(da)(da),腔(qiang)體(ti)(ti)(ti)(ti)與(yu)端蓋上的吸(xi)氣口相(xiang)通,其內氣體(ti)(ti)(ti)(ti)壓(ya)力降低,氣體(ti)(ti)(ti)(ti)被吸(xi)入(ru),吸(xi)氣結束時(shi)腔(qiang)體(ti)(ti)(ti)(ti)與(yu)吸(xi)入(ru)口隔離。壓(ya)縮過(guo)程(cheng)中,腔(qiang)體(ti)(ti)(ti)(ti)體(ti)(ti)(ti)(ti)積由大(da)(da)變小(xiao),其內氣體(ti)(ti)(ti)(ti)壓(ya)力升高(gao),在泵旋轉至(zhi)腔(qiang)體(ti)(ti)(ti)(ti)與(yu)排(pai)(pai)氣口相(xiang)通時(shi),氣體(ti)(ti)(ti)(ti)被排(pai)(pai)出。
水環(huan)式(shi)(shi)真空(kong)(kong)泵系(xi)(xi)(xi)(xi)統(tong)(tong)主要(yao)有閉(bi)式(shi)(shi)循(xun)環(huan)系(xi)(xi)(xi)(xi)統(tong)(tong)和(he)開式(shi)(shi)循(xun)環(huan)系(xi)(xi)(xi)(xi)統(tong)(tong)。閉(bi)式(shi)(shi)循(xun)環(huan)系(xi)(xi)(xi)(xi)統(tong)(tong)主要(yao)由真空(kong)(kong)泵、環(huan)液(ye)(ye)冷卻(que)器、分(fen)(fen)離罐(guan)(guan)及排液(ye)(ye)泵等組成。環(huan)液(ye)(ye)冷卻(que)器用于維持液(ye)(ye)環(huan)式(shi)(shi)真空(kong)(kong)泵的工(gong)作液(ye)(ye)溫度恒定,分(fen)(fen)離罐(guan)(guan)用于將泵出口氣體(ti)中的液(ye)(ye)體(ti)分(fen)(fen)離,同時進行環(huan)液(ye)(ye)的補充(chong)和(he)排放。開式(shi)(shi)循(xun)環(huan)系(xi)(xi)(xi)(xi)統(tong)(tong)為環(huan)液(ye)(ye)一次(ci)通過系(xi)(xi)(xi)(xi)統(tong)(tong),泵組無需配置冷卻(que)器,環(huan)液(ye)(ye)溫度由上游(you)工(gong)藝系(xi)(xi)(xi)(xi)統(tong)(tong)來控制。這(zhe)2種系(xi)(xi)(xi)(xi)統(tong)(tong)可以根據實際工(gong)藝能量衡算和(he)具體(ti)需求(qiu)進行選擇。
羅茨真空泵
羅茨真空(kong)泵(beng)一般分(fen)為直排(pai)大氣羅茨泵(beng)(低真空(kong))、中真空(kong)羅茨泵(beng)(又(you)稱機(ji)械(xie)增壓羅茨泵(beng))以及高真空(kong)多(duo)級羅茨泵(beng)。目前國內最為常用的是機(ji)械(xie)增壓羅茨泵(beng)。
在羅茨(ci)真空泵泵腔內,有1對8字形或三葉形的轉(zhuan)子相互垂(chui)直(zhi)地安(an)裝在1對平行軸上,由(you)1對同(tong)步齒輪帶動(dong)轉(zhuan)子做同(tong)步反向旋(xuan)轉(zhuan)運動(dong)。在轉(zhuan)子之間、轉(zhuan)子與泵殼內壁之間保持一定間隙,可以實(shi)現高轉(zhuan)速運行。
機械增(zeng)壓(ya)羅茨(ci)泵壓(ya)差小,但在(zai)較寬壓(ya)力(li)范(fan)圍(wei)內(nei)抽速高。機械增(zeng)壓(ya)羅茨(ci)泵不(bu)能(neng)單獨使(shi)用(yong),必(bi)須(xu)配置前(qian)級泵使(shi)用(yong)。啟(qi)動時需先啟(qi)動前(qian)級泵,待入口壓(ya)力(li)達到(dao)機械增(zeng)壓(ya)羅茨(ci)泵的允(yun)許壓(ya)差范(fan)圍(wei)內(nei)才(cai)能(neng)啟(qi)動羅茨(ci)泵。否則會(hui)導致(zhi)電(dian)機過載、泵轉子卡(ka)死等故障的發生(sheng)。
螺桿式真空泵
螺桿式真(zhen)空泵結構及工作原理如(ru)下(xia)。
螺桿(gan)(gan)式真空泵是通過(guo)1組同步齒輪(lun)或(huo)雙(shuang)電機驅動(無(wu)同步齒輪(lun))的(de)1對反向旋轉(zhuan)的(de)螺桿(gan)(gan)進(jin)行工作。在(zai)(zai)螺桿(gan)(gan)之間(jian)、螺桿(gan)(gan)與(yu)泵殼之間(jian)有一定間(jian)隙,保(bao)證金屬與(yu)金屬之間(jian)無(wu)接觸面,從而(er)實現轉(zhuan)子非接觸嚙合。氣(qi)體在(zai)(zai)螺桿(gan)(gan)的(de)旋轉(zhuan)過(guo)程中(zhong)被抽吸、壓(ya)縮(suo)后(hou)排出。
螺(luo)桿(gan)式真(zhen)(zhen)空(kong)泵(beng)可(ke)實現較(jiao)(jiao)高(gao)的(de)極限真(zhen)(zhen)空(kong),既可(ke)單(dan)獨(du)使用(yong),也可(ke)作前級泵(beng)。為達到較(jiao)(jiao)高(gao)真(zhen)(zhen)空(kong)度,同時(shi)保證螺(luo)桿(gan)式真(zhen)(zhen)空(kong)泵(beng)的(de)工(gong)作效率,對螺(luo)桿(gan)式真(zhen)(zhen)空(kong)泵(beng)轉子間隙(xi)、螺(luo)桿(gan)與泵(beng)殼的(de)間隙(xi)控(kong)制非常嚴格,對螺(luo)桿(gan)、同步齒輪(lun)的(de)加工(gong)精度要求很高(gao)。
螺桿式真空(kong)泵具有(you)結構緊湊、安裝(zhuang)維護簡單、抽速大、真空(kong)度高及(ji)壓比高等特點。其(qi)工作部件無摩擦,壽(shou)命長。
爪式真空泵
爪(zhua)式真(zhen)空泵(beng)目前(qian)使用的型式較多(duo)。臥式爪(zhua)式真(zhen)空泵(beng)一(yi)般為單(dan)級結構,泵(beng)組可獲得的真(zhen)空度不(bu)高,多(duo)用于形成粗真(zhen)空。
立式爪(zhua)式真(zhen)空(kong)泵(beng)一般為3級或4級壓縮,可(ke)獲得較(jiao)高的真(zhen)空(kong)度(du)。
立式(shi)爪(zhua)式(shi)真空(kong)(kong)泵(beng)(beng)的(de)(de)(de)泵(beng)(beng)腔(qiang)(qiang)依次串聯,每(mei)級(ji)(ji)泵(beng)(beng)腔(qiang)(qiang)內各有1對(dui)(dui)共軛(e)嚙合、做同步(bu)反向運動的(de)(de)(de)爪(zhua)型(xing)(xing)轉(zhuan)子(zi)(zi)。介(jie)質(zhi)被爪(zhua)型(xing)(xing)轉(zhuan)子(zi)(zi)吸(xi)(xi)入(ru)后壓縮(suo)并排放。轉(zhuan)子(zi)(zi)之(zhi)(zhi)間(jian)(jian)(jian)(jian)、轉(zhuan)子(zi)(zi)與(yu)(yu)(yu)泵(beng)(beng)殼之(zhi)(zhi)間(jian)(jian)(jian)(jian)均(jun)無接觸。每(mei)級(ji)(ji)泵(beng)(beng)腔(qiang)(qiang)中(zhong)的(de)(de)(de)第一級(ji)(ji)泵(beng)(beng)腔(qiang)(qiang)為吸(xi)(xi)氣(qi)級(ji)(ji),其(qi)吸(xi)(xi)氣(qi)體(ti)積(ji)比后面幾級(ji)(ji)的(de)(de)(de)大,形成級(ji)(ji)間(jian)(jian)(jian)(jian)壓縮(suo)。每(mei)對(dui)(dui)轉(zhuan)子(zi)(zi)安裝(zhuang)在2根(gen)平(ping)行軸上,軸由上、下(xia)兩(liang)端(duan)軸承支撐(cheng),泵(beng)(beng)腔(qiang)(qiang)級(ji)(ji)與(yu)(yu)(yu)級(ji)(ji)之(zhi)(zhi)間(jian)(jian)(jian)(jian)設有隔板(ban),隔板(ban)上有吸(xi)(xi)排氣(qi)通道。通過同步(bu)齒輪傳動并調(diao)整(zheng)轉(zhuan)子(zi)(zi)軸與(yu)(yu)(yu)固定轉(zhuan)子(zi)(zi)相(xiang)位,保證轉(zhuan)子(zi)(zi)之(zhi)(zhi)間(jian)(jian)(jian)(jian)及轉(zhuan)子(zi)(zi)與(yu)(yu)(yu)泵(beng)(beng)殼之(zhi)(zhi)間(jian)(jian)(jian)(jian)的(de)(de)(de)間(jian)(jian)(jian)(jian)隙(xi)。爪(zhua)式(shi)真空(kong)(kong)泵(beng)(beng)中(zhong)需控制的(de)(de)(de)間(jian)(jian)(jian)(jian)隙(xi)較多,如轉(zhuan)子(zi)(zi)之(zhi)(zhi)間(jian)(jian)(jian)(jian)的(de)(de)(de)間(jian)(jian)(jian)(jian)隙(xi),轉(zhuan)子(zi)(zi)與(yu)(yu)(yu)端(duan)蓋、隔板(ban)的(de)(de)(de)間(jian)(jian)(jian)(jian)隙(xi),轉(zhuan)子(zi)(zi)與(yu)(yu)(yu)泵(beng)(beng)體(ti)之(zhi)(zhi)間(jian)(jian)(jian)(jian)的(de)(de)(de)間(jian)(jian)(jian)(jian)隙(xi)等,這些間(jian)(jian)(jian)(jian)隙(xi)之(zhi)(zhi)間(jian)(jian)(jian)(jian)相(xiang)互關聯,給泵(beng)(beng)的(de)(de)(de)安裝(zhuang)及維護帶來一定不便,且一般爪(zhua)式(shi)真空(kong)(kong)泵(beng)(beng)抽速(su)較小。