空氣冷卻器分類及特點

1、濕式空冷器

濕(shi)式(shi)(shi)空(kong)(kong)冷(leng)器根據(ju)噴(pen)水(shui)方式(shi)(shi)，可(ke)分為(wei)表面蒸(zheng)發(fa)(fa)型(xing)、增(zeng)濕(shi)型(xing)和(he)噴(pen)淋(lin)型(xing)3種，在(zai)(zai)(zai)石化(hua)(hua)工業中以(yi)后(hou)(hou)兩種為(wei)主。表面蒸(zheng)發(fa)(fa)式(shi)(shi)空(kong)(kong)冷(leng)器是(shi)一種利用管外水(shui)膜蒸(zheng)發(fa)(fa)來強(qiang)(qiang)化(hua)(hua)傳(chuan)(chuan)(chuan)熱(re)、由光管組(zu)成的空(kong)(kong)冷(leng)裝(zhuang)置。增(zeng)濕(shi)型(xing)濕(shi)式(shi)(shi)空(kong)(kong)冷(leng)器只(zhi)適用于(yu)相(xiang)對濕(shi)度(du)低于(yu)50%的干燥、炎熱(re)地區，因為(wei)干空(kong)(kong)氣(qi)相(xiang)對濕(shi)度(du)越(yue)小(xiao)，增(zeng)濕(shi)后(hou)(hou)降(jiang)溫(wen)越(yue)多(duo)，冷(leng)卻(que)效果越(yue)顯(xian)著。噴(pen)淋(lin)型(xing)濕(shi)式(shi)(shi)空(kong)(kong)冷(leng)器是(shi)直接在(zai)(zai)(zai)翅片(pian)管束上噴(pen)霧狀水(shui)，利用水(shui)分蒸(zheng)發(fa)(fa)的潛熱(re)交(jiao)換(huan)和(he)空(kong)(kong)氣(qi)被增(zeng)濕(shi)降(jiang)溫(wen)來強(qiang)(qiang)化(hua)(hua)傳(chuan)(chuan)(chuan)熱(re)，同時，水(shui)霧的存在(zai)(zai)(zai)可(ke)使空(kong)(kong)冷(leng)器入口(kou)空(kong)(kong)氣(qi)溫(wen)度(du)接近環(huan)境濕(shi)球溫(wen)度(du)，提(ti)(ti)高了傳(chuan)(chuan)(chuan)熱(re)平均溫(wen)差，在(zai)(zai)(zai)3%噴(pen)淋(lin)量下換(huan)熱(re)系數可(ke)比干式(shi)(shi)空(kong)(kong)冷(leng)器提(ti)(ti)高2 ~4倍。

總之，相較于干式(shi)空冷器(qi)(qi)(qi)，在炎熱的夏季，環境(jing)氣(qi)(qi)溫較高時，應用濕(shi)式(shi)空冷器(qi)(qi)(qi)更為(wei)(wei)有利。但是(shi)，濕(shi)式(shi)空冷器(qi)(qi)(qi)在管內流體溫度超過70℃時，就極(ji)易結垢(gou)，且管外(wai)空氣(qi)(qi)阻力損失較大，約為(wei)(wei)干式(shi)空冷的1.4倍。管束面積不能(neng)太大，故(gu)單元裝(zhuang)置的相對面積較小，價格相對較高。

該圖片由注冊用戶"安居樂"提供，版權聲明反饋

2、干式空冷器

干式空(kong)(kong)(kong)冷器僅依靠空(kong)(kong)(kong)氣(qi)溫(wen)升的顯熱方式來交換熱量，靠翅片(pian)管(guan)和(he)風機強制(zhi)循環(huan)強化(hua)傳熱。操作簡(jian)單，使(shi)用方便，但(dan)由(you)于其冷卻(que)溫(wen)度(du)取決于空(kong)(kong)(kong)氣(qi)的干球溫(wen)度(du)，所以(yi)一般只(zhi)能把管(guan)內熱流體(ti)冷卻(que)到高于環(huan)境溫(wen)度(du)15~20℃。

因(yin)此(ci)，對(dui)于(yu)我國(guo)南方濕(shi)(shi)熱(re)(re)地區，濕(shi)(shi)式(shi)(shi)空(kong)(kong)(kong)(kong)(kong)冷(leng)(leng)器(qi)蒸發(fa)效(xiao)果不(bu)好，一(yi)般主要用干式(shi)(shi)空(kong)(kong)(kong)(kong)(kong)冷(leng)(leng)器(qi)。從熱(re)(re)量(liang)傳(chuan)遞(di)角(jiao)度(du)講(jiang)，空(kong)(kong)(kong)(kong)(kong)氣的(de)(de)(de)(de)比熱(re)(re)僅為(wei)(wei)水(shui)的(de)(de)(de)(de)比熱(re)(re)的(de)(de)(de)(de)1 /4，空(kong)(kong)(kong)(kong)(kong)氣的(de)(de)(de)(de)密(mi)度(du)也(ye)遠(yuan)小于(yu)水(shui)的(de)(de)(de)(de)密(mi)度(du)，因(yin)此(ci)，若傳(chuan)遞(di)相(xiang)(xiang)同的(de)(de)(de)(de)熱(re)(re)量(liang)，冷(leng)(leng)卻介(jie)質(zhi)溫升相(xiang)(xiang)同，所需要的(de)(de)(de)(de)空(kong)(kong)(kong)(kong)(kong)氣量(liang)將是(shi)(shi)水(shui)的(de)(de)(de)(de)4倍(bei)，相(xiang)(xiang)比于(yu)水(shui)冷(leng)(leng)卻器(qi)，干式(shi)(shi)空(kong)(kong)(kong)(kong)(kong)冷(leng)(leng)器(qi)的(de)(de)(de)(de)體積是(shi)(shi)很(hen)(hen)大(da)的(de)(de)(de)(de)。最(zui)關鍵(jian)(jian)的(de)(de)(de)(de)是(shi)(shi)，空(kong)(kong)(kong)(kong)(kong)氣側的(de)(de)(de)(de)換(huan)(huan)熱(re)(re)系數(shu)很(hen)(hen)低(di)(di)，約為(wei)(wei)50~60W/(m2·℃)，導致光(guang)管(guan)(guan)空(kong)(kong)(kong)(kong)(kong)冷(leng)(leng)器(qi)的(de)(de)(de)(de)總傳(chuan)熱(re)(re)系數(shu)很(hen)(hen)低(di)(di)，較(jiao)水(shui)冷(leng)(leng)卻器(qi)的(de)(de)(de)(de)傳(chuan)熱(re)(re)系數(shu)約低(di)(di)10~30倍(bei)，為(wei)(wei)抵消空(kong)(kong)(kong)(kong)(kong)氣側換(huan)(huan)熱(re)(re)系數(shu)較(jiao)低(di)(di)的(de)(de)(de)(de)影響，空(kong)(kong)(kong)(kong)(kong)冷(leng)(leng)器(qi)一(yi)般均采用擴展表面的(de)(de)(de)(de)翅(chi)(chi)片(pian)管(guan)(guan)，其翅(chi)(chi)化(hua)比大(da)致為(wei)(wei)10~24倍(bei)。也(ye)有采用板式(shi)(shi)傳(chuan)熱(re)(re)元件(jian)(jian)的(de)(de)(de)(de)板式(shi)(shi)空(kong)(kong)(kong)(kong)(kong)冷(leng)(leng)器(qi)，因(yin)為(wei)(wei)板片(pian)形成的(de)(de)(de)(de)流(liu)(liu)(liu)道(dao)斷面形狀沿流(liu)(liu)(liu)動(dong)(dong)方向(xiang)不(bu)斷變化(hua)，增(zeng)強了擾動(dong)(dong)，在(zai)低(di)(di)雷諾數(shu)下具(ju)有高(gao)(gao)的(de)(de)(de)(de)傳(chuan)熱(re)(re)效(xiao)率和(he)低(di)(di)的(de)(de)(de)(de)壓(ya)降，特別適用于(yu)石化(hua)行業大(da)型裝置(zhi)(如大(da)型乙(yi)烯成套設備(bei)等(deng))的(de)(de)(de)(de)空(kong)(kong)(kong)(kong)(kong)冷(leng)(leng)器(qi)，但(dan)是(shi)(shi)由于(yu)板式(shi)(shi)空(kong)(kong)(kong)(kong)(kong)冷(leng)(leng)器(qi)的(de)(de)(de)(de)流(liu)(liu)(liu)道(dao)狹窄(zhai)，在(zai)我國(guo)北方寒冷(leng)(leng)的(de)(de)(de)(de)冬季，容易引起(qi)流(liu)(liu)(liu)道(dao)內被冷(leng)(leng)卻介(jie)質(zhi)凝(ning)結而堵(du)塞(sai)流(liu)(liu)(liu)道(dao)，并且易結垢從而堵(du)塞(sai)流(liu)(liu)(liu)道(dao)，又由于(yu)加工(gong)工(gong)藝多為(wei)(wei)全焊(han)式(shi)(shi)結構，局部損壞或堵(du)塞(sai)時，必須(xu)整臺更換(huan)(huan)空(kong)(kong)(kong)(kong)(kong)冷(leng)(leng)器(qi)，造成很(hen)(hen)大(da)浪費(fei)。所以，翅(chi)(chi)片(pian)管(guan)(guan)仍然是(shi)(shi)空(kong)(kong)(kong)(kong)(kong)冷(leng)(leng)器(qi)的(de)(de)(de)(de)主流(liu)(liu)(liu)傳(chuan)熱(re)(re)元件(jian)(jian)，空(kong)(kong)(kong)(kong)(kong)冷(leng)(leng)器(qi)的(de)(de)(de)(de)本(ben)質(zhi)可以看(kan)為(wei)(wei)是(shi)(shi)空(kong)(kong)(kong)(kong)(kong)氣－熱(re)(re)媒的(de)(de)(de)(de)管(guan)(guan)翅(chi)(chi)式(shi)(shi)換(huan)(huan)熱(re)(re)器(qi)，強化(hua)空(kong)(kong)(kong)(kong)(kong)氣冷(leng)(leng)卻器(qi)傳(chuan)熱(re)(re)性能(neng)的(de)(de)(de)(de)關鍵(jian)(jian)是(shi)(shi)研制低(di)(di)接觸熱(re)(re)阻(zu)、高(gao)(gao)傳(chuan)熱(re)(re)效(xiao)能(neng)和(he)流(liu)(liu)(liu)動(dong)(dong)阻(zu)力(li)小的(de)(de)(de)(de)翅(chi)(chi)片(pian)管(guan)(guan)。當換(huan)(huan)熱(re)(re)器(qi)內部為(wei)(wei)壓(ya)力(li)較(jiao)高(gao)(gao)的(de)(de)(de)(de)流(liu)(liu)(liu)體時，管(guan)(guan)外(wai)加肋，就相(xiang)(xiang)當于(yu)用不(bu)承壓(ya)的(de)(de)(de)(de)廉價(jia)肋片(pian)取(qu)代承壓(ya)的(de)(de)(de)(de)優(you)質(zhi)管(guan)(guan)材，經濟效(xiao)果顯著。

3、干－濕聯合式空冷器

干(gan)－濕聯合(he)式(shi)(shi)(shi)空冷(leng)(leng)器(qi)，就是將干(gan)式(shi)(shi)(shi)空冷(leng)(leng)器(qi)與濕式(shi)(shi)(shi)空冷(leng)(leng)器(qi)組(zu)合(he)集成。組(zu)合(he)的(de)一般(ban)原(yuan)則(ze)是，在工(gong)(gong)藝(yi)流體高溫區用(yong)(yong)干(gan)式(shi)(shi)(shi)空冷(leng)(leng)器(qi)，起氣(qi)體冷(leng)(leng)凝(ning)的(de)作用(yong)(yong);在低溫區使用(yong)(yong)濕式(shi)(shi)(shi)空冷(leng)(leng)器(qi)，起冷(leng)(leng)凝(ning)液冷(leng)(leng)卻(que)的(de)作用(yong)(yong)。總之(zhi)，選擇哪種形式(shi)(shi)(shi)的(de)空冷(leng)(leng)器(qi)，要(yao)根據當(dang)地的(de)大氣(qi)溫度(du)、風速及相對濕度(du)等(deng)環(huan)境(jing)氣(qi)候條件，結(jie)合(he)介(jie)質最(zui)終冷(leng)(leng)卻(que)溫度(du)等(deng)換(huan)熱(re)工(gong)(gong)藝(yi)要(yao)求，并兼顧經濟(ji)性，進行(xing)綜合(he)考(kao)量確定(ding)。

空氣冷卻器通風方式

1、鼓風式：空氣(qi)先流經通(tong)風機后流入管束。

2、引(yin)風(feng)式：空氣先(xian)流經管束后流入(ru)通(tong)風(feng)機。前者操作費用(yong)較(jiao)經濟，產生的湍流對傳(chuan)熱有利，使用(yong)較(jiao)多。

后者氣流(liu)(liu)分布均(jun)勻，有利于溫(wen)(wen)度精確控制(zhi)，噪聲(sheng)小，是發展的(de)(de)(de)(de)方向。熱流(liu)(liu)體(ti)出口溫(wen)(wen)度主要靠調(diao)節(jie)(jie)通過管束的(de)(de)(de)(de)風量(liang)來控制(zhi)，即調(diao)節(jie)(jie)葉(xie)片的(de)(de)(de)(de)傾角、通風機轉速和(he)百葉(xie)窗的(de)(de)(de)(de)開啟程度等。對冬季易(yi)凝、易(yi)凍(dong)的(de)(de)(de)(de)流(liu)(liu)體(ti)，可(ke)采用(yong)熱風循環或蒸汽加熱的(de)(de)(de)(de)辦法(fa)調(diao)節(jie)(jie)流(liu)(liu)體(ti)出口溫(wen)(wen)度。