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1、目錄一、方案簡介································································1二、方案設(shè)計································································21、確定設(shè)計方案·····························································22、確定物性數(shù)據(jù)·······························
2、······························23、計算總傳熱系數(shù)···························································34、計算傳熱面積·····························································35、工藝結(jié)構(gòu)尺寸·····························································46、換熱器核算······
3、·························································5三、設(shè)計結(jié)果一覽表··························································8四、附圖(主體設(shè)備設(shè)計條件圖)(詳情參見圖紙)································8五、參考文獻································································9
4、三、主要符號說明····························································9四、心得體會·································································10附圖··········································································一、方案簡介本設(shè)計任務是利用冷流體(水)給硝基苯降溫。利用熱傳遞過程中
5、對流傳熱原則,制成換熱器,以供生產(chǎn)需要。下圖(圖1)是工業(yè)生產(chǎn)中用到的列管式換熱器.選擇換熱器時,要遵循經(jīng)濟,傳熱效果優(yōu),方便清洗,復合實際需要等原則。換熱器分為幾大類:夾套式換熱器,沉浸式蛇管換熱器,噴淋式換熱器,套管式換熱器,螺旋板式換熱器,板翅式換熱器,熱管式換熱器,列管式換熱器等。不同的換熱器適用于不同的場合。而列管式換熱器在生產(chǎn)中被廣泛利用。它的結(jié)構(gòu)簡單、堅固、制造較容易、處理能力大、適應性大、操作彈性較大。尤其在高壓、高溫和大型裝置中使用更為普遍。所以首選列管式換熱器作為設(shè)計基礎(chǔ)。9二、方
6、案設(shè)計某廠在生產(chǎn)過程中,需將硝基苯液體從100℃冷卻到45℃。處理能力為1.5×105噸/年。冷卻介質(zhì)采用自來水,入口溫度30℃,出口溫度40℃。要求換熱器的管程和殼程的壓降不大于10kPa。試設(shè)計能完成上述任務的列管式換熱器。(每年按330天,每天24小時連續(xù)運行)1.確定設(shè)計方案(1)選擇換熱器的類型兩流體溫度變化情況:熱流體進口溫度100℃,出口溫度45℃冷流體。冷流體進口溫度30℃,出口溫度40℃。從兩流體溫度來看,估計換熱器的管壁溫度和殼體壁溫之差不會很大,因此初步確定選用固定管板式換熱器。
7、(2)流動空間及流速的確定由于硝基苯的粘度比水的大,因此冷卻水走管程,硝基苯走殼程。另外,這樣的選擇可以使硝基苯通過殼體壁面向空氣中散熱,提高冷卻效果。同時,在此選擇逆流。選用ф25×2.5的碳鋼管,管內(nèi)流速取ui=0.5m/s。2、確定物性數(shù)據(jù)定性溫度:可取流體進口溫度的平均值。殼程硝基苯的定性溫度為:管程流體的定性溫度為:根據(jù)定性溫度,分別查取殼程和管程流體的有關(guān)物性數(shù)據(jù)。硝基苯在72.5℃下的有關(guān)物性數(shù)據(jù)如下:密度 ρo=1153kg/m3定壓比熱容 cpo=1.559kJ/(kg·℃)導熱系
8、數(shù) λo=0.129W/(m·℃)粘度 μo=0.000979Pa·s冷卻水在35℃下的物性數(shù)據(jù):密度 ρi=994.3kg/m3定壓比熱容 cpi=4.24kJ/(kg·℃)導熱系數(shù) λi=0.618W/(m·℃)粘度 μi=0.000818Pa·s3.計算總傳熱系數(shù)(1)熱流量熱流體的流量Wo=1.5×105×1000÷330÷24≈18939kg/h熱流量Qo=WocpoΔto=18939×1.559×(100-45)=1623925