列管式換熱器-煤油換熱器-化工原理課設文檔

設計題目：煤油冷卻器的設計設計者：班級：學號：日期：指導教師：設計成績：

目錄一、設計任務書····························································二、設計方案簡介··························································1.換熱器的選擇························································2.流體流動空間的選擇··················································三、主要物性參數(shù)··························································四、計算傳熱面積··························································1.熱流量·······························································2.平均傳熱溫度差·······················································3.冷卻水用量···························································4.估算傳熱面積·························································五、換熱器工藝結構尺寸·····················································1.管徑和徑內(nèi)流速·······················································2.管程數(shù)和傳熱管數(shù)·····················································3.傳熱管排列方式和分程方法·············································4.殼內(nèi)徑·······························································5.折流板·······························································六、換熱器核算·····························································1.總傳熱系數(shù)核算·······················································2.傳熱面積核算·························································3.裕量計算·····························································七、設計結果概要···························································八、設計的評述·····························································九、主要參考資料···························································十、換熱器總裝配圖·························································

一、設計任務書在某生產(chǎn)過程中，用循環(huán)冷卻水將煤油油由120℃冷卻至40℃。已知換熱器的年處理量為；水的進口溫度和出口溫度分別為30℃和40℃。假設610t4每年按330天計，每天24小時連續(xù)運行，試設計一臺列管式換熱器，完成該生產(chǎn)任務。二、設計方案簡介1.換熱器的選擇在本次設計任務中，兩流體的溫度變化情況為：熱流體（煤油）進口溫度120℃，出口溫度40℃；冷流體（循環(huán)水）進口溫度為30℃，出口溫度40℃。由于冷、熱流體間溫差較大，則殼體和管束熱膨脹程度不同，會已經(jīng)較大的內(nèi)應力。浮頭式換熱器有一端管板不與殼體相連，可沿軸自由伸縮，不但可以完全消除熱應力，而且在清洗和檢修時，整個管束可以從殼體中抽出?；谝陨蠋c，初步確定選用浮頭式換熱器。2.流體流動空間的選擇對列管式換熱器，流體流經(jīng)管程還是課程，遵循以下原則：○1不清潔或易結垢的流體宜走容易清洗的一側。對于直管管束，宜走管程；○2腐蝕性流體宜走管程，以免殼體和管束同時被腐蝕；○3為增大對流傳熱系數(shù)，需要提高流速的流體宜走管程；○4兩流體溫差較大時，對于固定管板式換熱器，宜將對流傳熱系數(shù)大的流體走殼程，以減小管壁和殼體的溫差，減小熱應力；○5蒸氣冷凝宜走殼程，以利于排除冷凝液；○6需要冷卻的流體宜走殼程，便于散熱，以減少冷卻劑用量；但溫度很高的流體，其熱能可以利用，宜走管程，以減少熱損失；○7黏度大或流量較小的流體宜走殼程，因有折流擋板的作用，在低Re下（Re＞100）即可達到湍流；對于本次設計任務，首先，煤油是需要冷卻的流體，為了利于散熱，宜走殼程；其次。由于循環(huán)水容易結垢，從利于清洗的角度分析，水宜走管程。綜合考慮，煤油走殼程，循環(huán)水走管程。三、主要物性參數(shù)定性溫度取冷、熱流體進出口溫度的算術平均值。

煤油的定性溫度為T12040℃；802循環(huán)水的定性溫度為t304035℃；2根據(jù)定性溫度，分別查出走殼程和管程的流體的有關物性參數(shù)。表一流體主要物性參數(shù)導熱系數(shù)流體密度/kgm3黏度/Pas比熱容C/JkgK11/PWm1K1煤油循環(huán)水8259940.147.151042.221030.6267.2251044.174103四、計算傳熱面積1.熱負荷令循環(huán)水和煤油的角標分別為1和2。根據(jù)設計任務，換熱器每年的處理量M6104t6107kg換熱器每年的工作時間330247920h，M6107則煤油的質量流量qm27575.76kg/h2.10kg/s7920根據(jù)熱量衡算方程QqC(tt)qC(TT)m1p121m2p212熱負荷QqC(TT)2.102.22103(12040)3.73105W1m2p222.平均傳熱溫度差1204080-10t==33.66逆流平均溫度差℃80ln104030m逆8010校正系數(shù)是輔助量R與P的函數(shù)，=f(R,P)。TT12040R1tt4030tt40308P20.11Tt12030其中，，122111假設為單殼程，根據(jù)圖1查得溫差校正系數(shù)=0.97，因為＞0.8，假設成立。則有tt=0.9733.66=32.65℃。mm逆

圖1.單殼程、四管程溫度校正系數(shù)圖3.冷卻水用量根據(jù)熱量衡算方程式QqC(TT)qC(tt)，m1p112m2p221冷卻水用量q=Q=3.73105(40-30)=8.94kg/sm1C(t-t)4.174103p1214.估算傳熱面積參考課本表4-7，選總傳熱系數(shù)K=250W/(m2K),根據(jù)Q=KAt，估估估m(xù)則有Q3.73105=45m.72A=估=Kt25032.65估m(xù)圖2.換熱器總傳熱系數(shù)K的選取范圍

五、換熱器工藝結構尺寸1.管徑和徑內(nèi)流速考慮到循環(huán)水容易結垢，為了便于清洗，所以管徑取252.5mm。則管內(nèi)徑d252.5220mm0.02m，管外徑d25mm0.025m。為了減少12循環(huán)水結垢的趨勢，徑內(nèi)流速不宜太小，取水的流速u1m/s。12.管程數(shù)和傳熱管數(shù)根據(jù)傳熱管內(nèi)徑和流速確定單程傳熱管數(shù)q8.94n28.629根m1d2u419940.7850.022111根據(jù)傳熱面積A估算管子長度為估A45.7L==20.1m估dn3.140.025292由于校正系數(shù)采用的是單殼程、四管程的，則每管程的管長選用，由換熱器系列標準初選浮頭式換熱器型號為l6000mmBES500-2.5-53.7-6/25-4Ⅰ。管總數(shù)N=116根，中心排管數(shù)為9，殼內(nèi)徑D=500mm，傳熱面積為53.7m2。3.傳熱管排列方式和分程方法為了管外清洗方便，且對流傳熱系數(shù)不至于太小，采取正方形錯列。取管中心距t1.25d1.252531.2532mm。2N116每管程的管數(shù)4.殼內(nèi)徑。n29根144根據(jù)初選的換熱器型號BES500-2.5-53.7-6/25-4Ⅰ，可知換熱器的殼內(nèi)徑為500mm。又采取多管程結構時，取管板利用率0.7，根據(jù)D1.05t1.0532116432mm可知，殼內(nèi)徑為500mm符合要求。N0.75.折流板采用弓形折流板，取弓形折流板圓缺高度為殼內(nèi)徑的25%，則切去的圓缺高度為b0.25d0.25500125mm。2取折流板間距h0.4d0.4500200mm。2

折流板數(shù)N傳熱管長l6。-1=-1=-1=29塊折流板間距h0.2B六、換熱器核算1.總傳熱系數(shù)核算（1）管程對流傳熱系數(shù)1q8.94管內(nèi)循環(huán)水的流速u10.988m/s，9940.7850.02292m1d2n4111du0.020.988994雷諾數(shù)Re1＞，湍流2.721041041117.2251041Cp114.1741037.2251040.626普朗特數(shù)Pr1，介于0.7～120，14.82Pr1l6長徑比300＞60，d0.02流體黏度2m7.15104Pas＜Pas,屬于低黏度流體，根據(jù)直管強制湍流對流傳熱系數(shù)公式，0.0231Re0.8Prn1d111循環(huán)水被加熱，n=0.4,則有0.626(2.72104)0.84.820.44766。0.020.0231Re0.8Pr0.023n1d111(2)殼程對流傳熱系數(shù)2d25殼程最大流通截面積，ShD(12)0.20.5(1)0.0219m2t32M6107q煤油流量煤油流速，7575.7kg6h/k2g.1s0/7920m2qu2.10，0.11m6s/m2S8250.0219224(t2d2)正方形排列的當量直徑d4(0.03220.7850.025)20.027m3.140.02542de2ud8250.1160.0273614210Re10雷諾數(shù)，＜＜，36Re222e7.1510422

Cp2普朗特數(shù)22.221037.1510411.34，0.14Pr22煤油被冷卻，則，()0.140.95w10.36R0.55Pr3()0.14根據(jù)有deew0.360.143601.545131.341。0.9W5m362K1/()20.027圖3.管外對流傳熱系數(shù)的計算方法（3）總傳熱系數(shù)取循環(huán)水側污垢熱阻R0.0003m4KW/，煤油側污垢熱阻為2d1，碳鋼的熱導率45W/(mK)，R0.00017m22KW/d2

則以外表面積A為基準的總傳熱系數(shù)為211ddbd22R12RKdd1dd2d2111m1250.000344476620204522.5250.00252510.0001723613.70103則K270W/(m2K)2.傳熱面積核算Q3.73105=42.3m2，與原來的估計值45.7m2基本相符。A=Kt27032.65m3.裕量計算A53.7==1.27選，即傳熱面積有27%的裕量。A42.3計算表明所選換熱器的規(guī)格可用。七、設計結果概要表二換熱器主要計算結果所選換熱器形式：浮頭式換熱器換熱器型號：BES500-2.5-53.7-6/25-Ⅰ4實際傳熱面積：42.3m2主要工藝參數(shù)管程名稱殼程煤油物料名稱循環(huán)水進口溫度/℃出口溫度/℃304012040操作溫度/℃熱負荷/W3.73105流量/kgh321840．9887575.760.1161流速/ms1

流體對流傳熱系數(shù)4766361/Wm2K1污垢熱阻/m2KW10.0003440.000172270總傳熱系數(shù)/Wm2K1程數(shù)41使用材料碳鋼碳鋼表三換熱器主要結構尺寸1166000管子規(guī)格/mm管間距/mm管數(shù)/根管長/mm252.532正方形錯列管子排列方式弓形500200125折流板型式殼體內(nèi)徑/mm折流板間距/mm切口高度/mm保溫層厚度/mm八、設計的評述本次化工原理課程設計，是對我們教材中第四章《傳熱》知識的綜合運用，對于我們了解傳熱過程的本質以