课程设计-列管式换热器设计

设计（论文）题目：列管式换热器的设计目录1前言························································32设计任务及操作条件··············································33列管式换热器的工艺设计·········································33.1换热器设计方案的确定··········································33.2物性数据的确定················································43.3平均温差的计算················································43.4传热总系数Ｋ的确定············································43.5传热面积A的确定··············································63.6主要工艺尺寸的确定············································63.6.1管子的选用·················································63.6.2管子总数n和管程数Np的确定··································63.6.3校核平均温度差tm及壳程数Ns·································73.6.4传热管排列和分程方法········································73.6.5壳体内径··················································73.6.6折流板····················································7课程设计23.7核算换热器传热能力及流体阻力··································73.7.1热量核算···················································73.7.2换热器压降校核·············································94列管式换热器机械设计············································104.1壳体壁厚的计算················································104.2换热器封头选择················································104.3其他部件······················································115课程设计评价·····················································115.1可靠性评价····················································115.2个人感想······················································116参考文献··························································11附表换热器主要结构尺寸和计算结果·······························121前言换热器（英语翻译：heatexchanger），是将热流体的部分热量传递给冷流体的设备，又称热交换器。换热器是化工、石油、动力、食品及其它许多工业部门的通用设备，在生产中占有重要地位。在化工生产中换热器可作为加热器、冷却器、冷凝器、蒸发器和再沸器等，应用更加广泛。换热器种类很多，但根据冷、热流体热量交换的原理和方式基本上可分三大类即：间壁式、混合式和蓄热式。列管式换热器工业上使用最广泛的一种换热设备。其优点是单位体积的传热面积、处理能力和操作弹性大，适应能力强，尤其在高温、高压和大型装置中采用更为普遍。列管式换热器主要有以下几个类型：固定管板式换热器、浮头式换热器、U形管式换热器等。设计一个比较完善的列管式换热器，除了能满足传热方面的要求外，还应该满足传热效率高、体积小、重量轻、消耗材料少、制造成本低、清洗维护方便和操作安全等要求。列管式换热器的设计，首先应根据化工生产工艺条件的要求，通过化工工艺计算，确定换热器的传热面积，同时选择管径、管长，确定管数、管程数和壳程数，课程设计3然后进行机械设计。2设计任务及操作条件2.1设计题目：用水冷却甲苯的列管式换热器设计2.2设计任务及操作条件某生产过程中，用循环冷却水冷却柴油。1、甲苯入口温度：80℃，出口温度：50℃2、甲苯流量：33125kg/h，压力：0.4~0.6MPa3、循环冷却水压力：0.4~0.6MPa，入口温度：30℃，出口温度：40℃已知甲苯的有关物性数据：密度ρ1=867kg/m3；定压热比容cp，1=1.85kJ/(kg·℃)；热导率λ1=0.126W/(m·℃)；黏度μ1=3.75×10-4Pa·s3列管式换热器的工艺设计3.1换热器设计方案的确定甲苯入口温度80℃，出口温度50℃，冷却水入口温度30℃，出口温度40℃。壳体和管束壁温差较大，且考虑到冷却水易结垢，需要清洗，故选用浮头式换热器。冷却水走管程，甲苯走壳程。因逆流时的平均温度差最小，传热推动力大，可节省冷却介质的用量，操作无特殊要求，故流动方式选逆流。选用φ25×2.5的碳钢管，管内流速设为ui=1.5m/s。3.2物性数据的确定定性温度：可取流体进口温度的平均值。壳程甲苯的定性温度：6525080T℃管程冷却水的定性温度：3524030T℃壳程甲苯65℃物性数据：密度ρ1=867kg/m3；定压热比容cp，1=1.85kJ/(kg·℃)；热导率λ1=0.126W/(m·℃)；黏度μ1=3.75×10-4Pa·s管程冷却水35℃时物性数据：查《化工原理》附表可知密度ρ2=994.3kg/m3；定压热比容cp，2=4.174kJ/(kg·℃)；热导率λ2=0.62W/(m·℃)；课程设计4黏度μ2=7.43×10-4Pa·s3.3平均温差的计算1、对于逆流换热过程，其平均温差可按式（3－1）进行计算：2121lntttttm（3－1）式中，Δt1、Δt2分别为大端温差与小端温差。当Δt1/Δt22时，可用算术平均值：221tttmΔt1=80-40=40℃Δt2=50-30=20℃Δt1/Δt2=2℃△△△△△85.282040ln2040ln2121tttttm3.4传热总系数Ｋ的确定用式（3－2）进行Ｋ值核算。（3－2）式中：－给热系数，W/m2·℃；R－污垢热阻，m2·℃／W；δ－管壁厚度，mm；λ－管壁导热系数，W/m·℃；下标ｉ、ｏ、ｍ分别表示管内、管外和平均。A0=4d02=4×252=490.63mm2Ai=4di2=4×202=314.16mm2Ｋ＝１＋＋＋＋100000RddRddddmiiii课程设计540.402216.31463.4902AAAoimmm2查《化工原理》附表可知Rsi=5.16×10-4m2·℃/WRso=1.72×10-4m2·℃/Wλ=50W/m·℃管程Re=μdu=00743.00.3994.512.00=40146.6管程传热系数i可由公式（3—3)计算i=Red23.00i0.8)cp（n（3—3)冷却水被加热，取n=0.4i=0.0232.002.60×40146.60.8×）（2.6000743.007.140.4=412.6W/（m2·℃）假设取壳程传热系数为600W/（m2·℃）用公式（3—4）对K计算Ｋ＝１＋＋＋＋100000RddRddddmiiii（3—4）式中：－给热系数，W/m2.℃；R－污垢热阻，m2.℃／W；δ－管壁厚度，mm；λ－管壁导热系数，W/m.℃；下标ｉ、ｏ、ｍ分别表示管内、管外和平均。20.006.41225.0020.0025.0000516.00225.005025.00025.00000172.060011K=179.5W/m2.℃3.5传热面积A的确定换热器的传热量Q=Whcph(T1-T2)=33125×1.85×(80-50)=1.84×106kJ/h=511kw68.9885.285.179511000KQAmt△m2课程设计6考虑15%的面积裕度，A=1.15×98.68=113.48m23.6主要工艺尺寸的确定3.6.1管子的选用选用φ25×2.5传热管（碳钢），取管内流速ui=1.5m/s3.6.2管子总数n和管程数Np的确定先按单管程计算单程传热管数ns，由式（3－5）进行计算。udVniss24（3－5）式中Vs－管程流体体积流量，m3/s；di－管子内径，m；u－管内适宜流速，m/s。冷却水用量hkgtcQipi/44125)3040(17.41840000W0C△根272.265.102.002.014.33.994/3600/441254sn按单程管计算，所需的传热管长度mndAso54.5327025.014.3113.48l0管长l过长则采用多管程，此时管长一般多选6m（L=6m）。该换热器管程数为99.8654.53NpLl传热管总根数n=ns×Np=27×9=243(根）3.6.3校核平均温度差tm及壳程数NsP=2.030803040R=330405080按单壳程多管程（Np）查图得Δt=0.93，Δt﹥0.8符合要求mtmtt=0.93×28.85=26.83℃3.6.4传热管排列和分程方法采用组合排列法，即每程内均按正三角形排列，隔板两侧采用正方形排列。课程设计7取管心距odt25.1，则t=1.25×25=31.25mmmm32横过管束中心线的管数nc=1.19196.18243(根）3.6.5壳体内径采用多管程结构，取管板利用率7.0，则壳体内径mmNtD6267.0/2433205.1/05.1圆整可取mmD7003.6.6折流板采用弓形折流板，取弓形折流板圆缺高度为壳体内径的%25，则切去的圆缺高度为mmh17570025.0取折流板间距DB4.0，则mm2807000.4.3D0B取B=300mm（根）折流板数为191-30060001-BLNB折流板圆缺水平装配。3.7核算换热器传热能力及流体阻力3.7.1热量核算(1)壳程对流传热系数对圆缺形折流板，可采取克恩公式14.03/155.0PrRe36.0wooeood当量直径，由正三角形排列得m020.0025.014.3025.0414.3032.0234dd4t234d22o2o2e壳程流通截面积20m043.0032.0025.017.0.2801AtdBDo壳程流体流速及其雷诺数分别为课程设计8smuo/247.0043.0)8673600/(331256.9419000375.0867215.002.0Reo普兰特准数51.5126.0000375.01085.1Pr3粘度校正14.0W=1.035)·/(556035.151.56