列管式换热器-煤油换热器-化工原理课设

设计题目：煤油冷却器的设计设计者：班级：学号：日期：指导教师：设计成绩：目录一、设计任务书····························································二、设计方案简介··························································1.换热器的选择························································2.流体流动空间的选择··················································三、主要物性参数··························································四、计算传热面积··························································1.热流量·······························································2.平均传热温度差·······················································3.冷却水用量···························································4.估算传热面积·························································五、换热器工艺结构尺寸·····················································1.管径和径内流速·······················································2.管程数和传热管数·····················································3.传热管排列方式和分程方法·············································4.壳内径·······························································5.折流板·······························································六、换热器核算·····························································1.总传热系数核算·······················································2.传热面积核算·························································3.裕量计算·····························································七、设计结果概要···························································八、设计的评述·····························································九、主要参考资料···························································十、换热器总装配图·························································一、设计任务书在某生产过程中，用循环冷却水将煤油油由120℃冷却至40℃。已知换热器的年处理量为4610t；水的进口温度和出口温度分别为30℃和40℃。假设每年按330天计，每天24小时连续运行，试设计一台列管式换热器，完成该生产任务。二、设计方案简介1.换热器的选择在本次设计任务中，两流体的温度变化情况为：热流体（煤油）进口温度120℃，出口温度40℃；冷流体（循环水）进口温度为30℃，出口温度40℃。由于冷、热流体间温差较大，则壳体和管束热膨胀程度不同，会已经较大的内应力。浮头式换热器有一端管板不与壳体相连，可沿轴自由伸缩，不但可以完全消除热应力，而且在清洗和检修时，整个管束可以从壳体中抽出。基于以上几点，初步确定选用浮头式换热器。2.流体流动空间的选择对列管式换热器，流体流经管程还是课程，遵循以下原则：○1不清洁或易结垢的流体宜走容易清洗的一侧。对于直管管束，宜走管程；○2腐蚀性流体宜走管程，以免壳体和管束同时被腐蚀；○3为增大对流传热系数，需要提高流速的流体宜走管程；○4两流体温差较大时，对于固定管板式换热器，宜将对流传热系数大的流体走壳程，以减小管壁和壳体的温差，减小热应力；○5蒸气冷凝宜走壳程，以利于排除冷凝液；○6需要冷却的流体宜走壳程，便于散热，以减少冷却剂用量；但温度很高的流体，其热能可以利用，宜走管程，以减少热损失；○7黏度大或流量较小的流体宜走壳程，因有折流挡板的作用，在低Re下（Re＞100）即可达到湍流；对于本次设计任务，首先，煤油是需要冷却的流体，为了利于散热，宜走壳程；其次。由于循环水容易结垢，从利于清洗的角度分析，水宜走管程。综合考虑，煤油走壳程，循环水走管程。三、主要物性参数定性温度取冷、热流体进出口温度的算术平均值。煤油的定性温度为12040802T℃；循环水的定性温度为3040352t℃；根据定性温度，分别查出走壳程和管程的流体的有关物性参数。表一流体主要物性参数流体密度/3kgm黏度/Pas比热容PC/11JkgK导热系数/11WmK煤油82547.151032.22100.14循环水99447.2251034.174100.626四、计算传热面积1.热负荷令循环水和煤油的角标分别为1和2。根据设计任务，换热器每年的处理量47610610Mtkg换热器每年的工作时间330247920h，则煤油的质量流量726107575.76/2.10/7920mMqkghkgs根据热量衡算方程11212212()()mpmpQqCttqCTT热负荷352212()2.102.2210(12040)3.7310mpQqCTTW2.平均传热温度差120404030逆流平均温度差80-10==33.6680ln10mt逆℃8010校正系数是辅助量R与P的函数，=f(R,P)。其中，12211204084030TTRtt，211140300.1112030ttPTt假设为单壳程，根据图1查得温差校正系数=0.97，因为＞0.8，假设成立。则有=0.9733.66=32.65mmtt逆℃。3.冷却水用量根据热量衡算方程式11122221()()mpmpQqCTTqCtt，冷却水用量5131213.7310===8.94kg/s(t-t)4.17410(40-30)mpQqC4.估算传热面积参考课本表4-7，选总传热系数2=250/(m)KWK估,根据=KtmQA估估，则有523.7310===45.7t25032.65mQAmK估估图1.单壳程、四管程温度校正系数图图2.换热器总传热系数K的选取范围五、换热器工艺结构尺寸1.管径和径内流速考虑到循环水容易结垢，为了便于清洗，所以管径取252.5mm。则管内径1252.52200.02dmmm，管外径2250.025dmmm。为了减少循环水结垢的趋势，径内流速不宜太小，取水的流速11/ums。2.管程数和传热管数根据传热管内径和流速确定单程传热管数1221118.9428.6299940.7850.0214mqndu根根据传热面积A估估算管子长度为245.7==20.13.140.02529ALmdn估由于校正系数采用的是单壳程、四管程的，则每管程的管长选用6000lmm，由换热器系列标准初选浮头式换热器型号为BES500-2.5-53.7-6/25-4Ⅰ。管总数N=116根，中心排管数为9，壳内径D=500mm，传热面积为53.72m。3.传热管排列方式和分程方法为了管外清洗方便，且对流传热系数不至于太小，采取正方形错列。取管中心距21.251.252531.2532tdmm。每管程的管数11162944Nn根。4.壳内径根据初选的换热器型号BES500-2.5-53.7-6/25-4Ⅰ，可知换热器的壳内径为500mm。又采取多管程结构时，取管板利用率0.7，根据1161.051.05324320.7NDtmm可知，壳内径为500mm符合要求。5.折流板采用弓形折流板，取弓形折流板圆缺高度为壳内径的25%，则切去的圆缺高度为20.250.25500125bdmm。取折流板间距20.40.4500200hdmm。折流板数6-1=-1=-1=290.2BlNh传热管长块折流板间距。六、换热器核算1.总传热系数核算（1）管程对流传热系数1管内循环水的流速11221118.940.988/9940.7850.02294mqumsdn，雷诺数41111410.020.988994Re2.72107.22510du＞410，湍流普朗特数3411114.174107.22510Pr4.820.626pC，1Pr介于0.7～120，长径比63000.02ld＞60，流体黏度47.1510Pas＜2mPas,属于低黏度流体，根据直管强制湍流对流传热系数公式0.8111110.023RePrnd，循环水被加热，n=0.4,则有0.840.80.4111110.6260.023RePr0.023(2.7210)4.820.02nd4766。(2)壳程对流传热系数2壳程最大流通截面积2225(1)0.20.5(1)0.021932dShDmt，煤油流量726107575.76/2.10/7920mMqkghkgs，煤油流速2222.100.116/8250.0219mqumsS，正方形排列的当量直径2222224()4(0.0320.7850.025)40.0273.140.025etddmd雷诺数222428250.1160.027Re36147.1510eud，3210＜2Re＜610，普朗特数3422222.22107.1510Pr11.340.14pC，煤油被冷却，则0.14()0.95w，根据10.550.1430.36Pr()eewRd有10.552320.140.36361411.340.95361/()0.027WmK。（3）总传热系数取循环水侧污垢热阻210.00034/dRmKW，煤油侧污垢热阻为220.000172/dRmKW，碳钢的热导率45/()WmK，图3.管外对流传热系数的计算方法则以外表面积2A为基准的总传热系数为22212111232111125250.00252510.0003440.000172476620204522.53613.7010270/(m)ddmdddbRRKdddKWK则2.传热面积核算523.7310==42.327032.65mQAmKt，与原来的估计值245.7m基本相符。3.裕量计算53.7==1.2742.3AA选，即