化工原理课程设计再沸器的设计

操作条件壳程温度/C:151.7(冷凝温度T)137.8(沸点tb)压力(绝)/MPa0.50.12蒸发量/(kg)10864.61壳程凝液物性(151.7C)管程流体物性(137.8C)]液相气相潜热rc=2113.2kJ/kgrb=310.3kJ/kg热导率入c=0.684W/(m-K)入b=0.104W/(m-K)黏度nc=0.186/mPa-snb=0.22/mPa-snv=0.0085/mPa-s「密度3pc=917kg/m3pb=977.5kg/m3・-3pv=3.955kg/m比热容Cpb=1.6748kJ/(kg-K)表面张力o-b=19.6mN/m蒸汽压曲线斜率(At/△p)s=2.159x10-3K-nVkg再沸器的设计一、设计条件以在五个大气压下(0.5Mpa)的饱和水蒸汽作为热源。设计条件如下：(1)管程压力、、管程压力(以塔底压力计算)：Pw105.30,721120KPa0.12MPa(2)将釜液视为纯氯苯，在釜底压力下，其沸点:根据安托因公式：10gpACBt查资料得：A=9,25B=225,69C=1516.04则有:log(0.12106则有:log(0.12106)1516.04tb225.69tb=137.8C(3)再沸器的蒸发量由于该塔满足包摩尔流假设，则再沸器的蒸发量:DbVM282.42112.6110864.61kg/h

(4)氯苯的汽化潜热常压沸点下的汽化潜热为35.3X103KJ/Kmol(即为313.5KJ/kg),纯组分的汽化潜热与温度的关系可用下式表示:「20.38「10.38t^—t^(tc=359.2C)tcti其中t2tb其中t2tb137.80.38359.2137.8038313.5310.3KJ/kg「2359.2131.8二、工艺结构尺寸的估算(1)、计算传热速率QQDbrb10864.61310.31000/36009.3647105W(2)、计算传热温差△tm△t后『3=151.7-137.8=13.9C(3)、假定传热系数K依据壳程及管程中介质的种类，按竖直管式查表，从中选取K=800W/(M.k)(4)、计算传热面积AApQKtmApQKtm一一一_59.364710580013.9=84m2(5)、传热管规格选为①25m诉2mmL=4000mn#正三角形排列,则传热管的根数为Nt-A-84268(根)doL3.140.0254(6)、壳体直径

按3.4.3.2节中介绍的方法求取壳体直径。由$3a(a1)1268解得a9(另外一负值舍去)则b2a119。于是：Dt(b1)3do32(191)325648mm取进口管直径Di250mm,出口管直径D。600mm三、传热系数校核1.显热段传热系数KL①假设传热管出口气化率为xe0.13,釜液蒸发量为D,则循环量W为Xfl/Db10864.61W」30(kg/s)xe36000.10②显然段传热管内传热膜系数设传热管内流通截面积为Si,则传热管内釜液的质量流率G为Si(4)di2NT0.7850.02122680.928m2W30W30Si0.09282325.05kg/(m2RediGb0.021325.0530.22103RediGb0.021325.0530.2210331027PrCpbb1.6748103022103

0.1043.543显热段传热管内传热膜系数i为i0.023—Re°8Pr0.4740.75W/(m2?K)di③壳程冷凝传热膜系数。23。1.87(cg2c)1/3Re。1/37747.5W/(m2?K)

④污垢热阻沸腾侧：R4.299105m2?K/W冷凝侧：RO1.72105m2?K/W管壁：Rw4.299106m2?K/W⑤显热段的传热系数KlKlTOC\o"1-5"\h\z~~Rd~~RwdoD~~1-~~~；Ro一idididm(1

560.0254.2991050.0254.2291060.025511.72104770.0210.0210.02311369.7376.44[W/(m2?K)].蒸发段传热系数Ke(1)管内沸腾-对流传热膜系数vabbtp①泡核沸腾的平均修正系数aaEa

a2Gh3600G3600325.051.17106kg/(m2?h)(V)0.5(b)0.1Gh3600G3600325.051.17106kg/(m2?h)(V)0.5(b)0.1

bv3.955977.5)0.5(0.220.0085)0.10.08807当xxe0.10时x0.021Xtt一)0.9x0.1310.131.5720.08807查图得aE=0。当x0.4xe0.04时入ttx0.0084(F)当x0.4xe0.04时入ttx0.0084(F)0.9x0.0410.04)0.90.088070.65查图得a=0.43aEaaEa00.4320.215②泡核沸腾传热膜系数b0.225—Pr069(_QdL)0.69(-1严(也严0.22501043.543S69

dArbbv0.021____5____(9.365100021X0.69\ZI_1_3~?S)329310.31030.221032163W/(m2?K),977.5,、0.33/1.21052163W/(m2?K)(-1)(-2-)3.9551.96102③质量分数x=0.4Xe处的对流传热膜系数tp3.5(—)0.53.50.650.52.82Xtttp0.023—Re(1x)tp0.023—Re(1x)0.8Pr0.40.023di0.104小2.8231027(10.0210.04)°.83.5430.42023.3W/(m2?K)④管内沸腾-对流传热膜系数vabbtp0.2316312023.32058.4W/(m2?K)(2)蒸发段传热系数KeKe(吉vvabbtp0.2316312023.32058.4W/(m2?K)(2)蒸发段传热系数KeKe(吉vdiRid。RwdodidmRo1)*10252058.4214.29910215254.2991062551.721023112―)11281W/(m2?K)7747.5.显热段和蒸发段长度显热段长度Lbc和传热管总长L之比为LbcLbcL0.439832.159103.140.0211047376.4413.91674.8977.530LBC0.439841.7592(m)LCD41.75922.2408(m).平均传热系数KcKcKlLbcKeLcd376.441.759210422.2408960Mm2?Kc.面积裕度核算比较K计算和K假定，若K计算比K假定高出20%则说明假定值尚可,否则要重新假定K值。KcKKcKK96080080020.11%四、循环流量的校核1.循环推动力Pd当x1Xe0.033时，1.循环推动力Pd当x1Xe0.033时，Xtt3(1X)0.9

X10.08807(-0.033)0.90.0330.6363RlXtt

2Z0-5(Xtt21Xtt1)0.50.636320-5(0.6363210.63631)0.279tpv(1Rl)bRL3.955(10.279)977.50.279275.9kg/m3当xXe时，按上述同样的方法求得tp165kg/m3查表并根据焊接需要选取再沸器上部管板至接管入塔口间的高度0.9m计算循环推动力PdpDgLcd(bptp)ltp9.812.2408(977.5245.8)0.916513397Pa.循环阻力pfPfPiP2P3P4P5(1)管程进口管阻力PiG—W-^302615.1kg/(m2?s)0.785Di20.7850.252ReiDiGReiDiG0.25615.10.221036.99105Li0.012270.7543..RLi0.012270.7543..Rei0.380.01682。0.0254)20.3426(Di0.02540.1914)(0.250.0254)20.3426(0.250.02540.1914)29.3mLG2P1i7249PaDi2b(2)加速损失p2(1Xe)2Rl6.85(1Xe)2Rl6.852N2Nt2325.05kg/(m2?s)__2__2__PGM/b187.539.14/977.5740Pa(3)传热管显热段阻力损失P3按直管阻力损失计算0.012270.7543R：380.012270.7543/310270380.0271P3LP3LbcG2di2b122Pa(4)传热管蒸发段阻力损失p4该段为两相流，故其流动阻力损失计算应按两相流考虑。计算方法是分别计算该段的气液两相流动的阻力，然后按一定方法加和，求得阻力损失。①气相流动阻力损失Pv4取该段内的平均气化率x2Xe0.067,则气相质量流速G为32-、GVxG0.067325.05kg/(m?s)气相流动的ReV:ReVdGV53536V0.7543v0.01227―03^0.0243RevPV4VLcd-G^153Padi2v②液相流动损失Pl4__2_GlGGV303.38kg/(m2GldjGdjGL0.021303.380.2210-3289590.75430.01227-^3^0.0275RPL4LLcdGl138Padi2b③两相压降P4,14P4(PV4144P,14P4(PV4144PL4)2333Pa(5)管程出口阻力P5①气相流动阻力损失Pv5出口管中气相质量流率为:c八302cGvxeG0.10221.67kg/(m2?s)0.7850.62出口管中气相流动的Rev为:RevDRevDoGv怒篝1521060.01227。.%30.0152Rev__2__2(Di/0.0254)0.3426(Di/0.02540.1914)__2(0.6/0.0254)0.3426(0.6/0.02540.1914)69.51mPV5v-GV-222PaDo2v②液相流动阻力Pl5液相流率Gl为：GlGGv680.7850.622_31.26209.2kg/(m2?s)液相C动ReL为:ReL吗0.6209.20.22103_55.710L0.012270.75430.027480.38ReL