1、塔设计例题讲解1、设计题目:年产8000吨乙醇板式精馏塔工艺设计2、已知条件:A.进料 F=6kmol/h q=0 Xf=0.45 B.压力: p顶=4KPa单板压降0.7KPa C.采用电加热,塔顶冷凝水采用12深井水 D.要求:Xd=0.88Xw=0.01 E.选定 R/Rmin=1.63、设计要求(1)物料流程图,塔版图,塔体工艺图(2)各接口尺寸(3)加热剂及冷却剂用量。二、 设计方案选定2.1 精馏方式:本设计采用连续精馏方式。原料液连续加入精馏塔中,并连续收集产物和排出残液。其优点是集成度高,可控性好,产品质量稳定。由于所涉浓度范围内乙醇和水的挥发度相差较大,因而无须采用特殊精馏。
2、2.2 操作压力:本设计选择常压,常压操作对设备要求低,操作费用低,适用于乙醇和水这类非热敏沸点在常温(工业低温段)物系分离。2.3 塔板形式:根据生产要求,选择结构简单,易于加工,造价低廉的筛板塔,筛板塔处理能力大,塔板效率高,压降教低,在乙醇和水这种黏度不大的分离工艺中有很好表现。2.4 加料方式和加料热状态:加料方式选择加料泵打入。由于原料温度稳定,为减少操作成本采用30度原料冷液进料。2.5 由于蒸汽质量不易保证,采用间接,蒸汽加热。2.6 再沸器,冷凝器等附属设备的安排:塔底设置再沸器,塔顶蒸汽完全冷凝后再冷却至65度回流入塔。冷凝冷却器安装在较低的框架上,通过回流比控制期分流后,用
3、回流泵打回塔内,馏出产品进入储罐。塔釜产品接近纯水,一部分用来补充加热蒸汽,其余储槽备稀释其他工段污水排放。三、总体设计计算3.1汽液平衡数据(760mm Hg)乙醇%(mol)温度 液相X 气相Y 0.00 0.00 100 1.90 17.00 95.5 7.21 38.91 89.0 9.66 43.75 86.712.38 47.04 85.316.61 50.89 84.123.37 54.45 82.726.08 55.80 82.332.73 58.26 81.539.65 61.22 80.750.79 65.64 79.851.98 65.99 79.757.32 68.41
4、 79.367.63 73.85 78.7474.72 78.15 78.4189.43 89.43 78.153.2 物料衡算3.2.1已知:A.进料:F=6 kmol/h q=0 Xf=0.45B.压力:p顶=4KPa单板压降0.7KPaC.采用电加热,塔顶冷凝水采用12深井水D.要求:Xd=0.88 Xw=0.01E、选定:R/Rmin=1.6D=(Xf-Xw)/(Xd-Xw)F =(0.45-0.01)/(0.88-0.01)6=3.03 kmol/hW=F-D=6-3.03=2.97 kmol/h查y-x图得 Xd/(Rmin+1)=0.218Rmin=3.037 R=1.6Rmin
5、=4.859饱和蒸汽进料 q=0L=RD=4.8593.03=14.723 kmol/hV=(R+1)D=(4.859+1)3.03=17.753 kmol/hL=L+qF=14.723+06=14.723 kmol/hV=V-(1-q)F=17.753-(1-0)6=11.753 kmol/h1.3操作线及塔板计算1.精馏段操作线:Y=RX/(R+1)+Xd/(R+1)Y=0.829X+0.1503.2.2.提馏段操作线:Y=(L/V)X-(W/V)Xw Y=1.253X-0.000253.3.理论塔板的计算利用计算机制图取得理论板数Nt=29.33块, 其中精馏段塔板Nt1=26.85块,
6、第27块为加料板,提馏段Nt2 =2.48块。3.4全塔Et%和Np的计算3.4.1.精馏段:t=(t顶+t进)=(79.25+87.32)/2=83.285Xa=0.34 Xb=1-Xa=0.66Ya=0.59 Yb=1-Ya=0.41查得液体粘度共线图 a=0.382 cp, b=0.592 cpL=YaXbL/XaYb=1.454查得:Et1%=0.49(L) -0.245=0.5471Np1=Nt1/Et1=49.083.4.2. 提馏段:t=(t底+t进)/2=(99.9+87.32)/2=93.61Xa=0.045 Xb=1-Xa=0.955Ya=0.27 Yb=1-Ya=0.73
7、0查得液体粘度共线图 a=0.468cp,b=0.532cpL=Xii=0.0450.468+0.9550.532=0.5291L=YaXbL/XaYb=4.15查得:Et2%=0.49(L) -0.245=0.346Np2=Nt2/Et2=7.17Np=Np1+Np2=49.08+7.17=56.25圆整为57块 其中精馏段49块,提馏段8块。四、混合参数计算4.1混合参数计算溶质 C2H5OH 分子量 : Ma=46.07 kg/kmol 溶剂 H2O分子量:Mb=18.016 kg/kmola=0.789 g/ml b=1.000 g/ml4.1.1精馏段:进料板液体温度 :t进=87.
8、32 塔顶温度:t顶=79.25 tm=(87.32+79.25)/2=83.285Xm=0.34 Ym=0.59a=0.382cp b=0.592cpMl=XmMa+(1-Xm)Mb=0.3446.07+(1-0.34)18.016=2*5 kg/kmolMg=YmMa+(1-Ym)Mb=0.5946.07+(10.59)18.016=34.56 kg/kmol质量分率: Wa=XmMa/Ml=0.3446.07/2*5=0.6855 Wb=1-Wa=1-0.6855=0.31451/l= Wa/a+Wb/b=0.6855/0.789+0.3145/1.00l=845.1 kg/m3 P=1
9、05325Pav=PMg/RT=10532534.56/(8314 (273.15+79.25)v=1.2424 kg/m34.1.2提馏段:t进=87.32t底=99.9tm=93.61 Xm=0.045 Ym=0.27 Ml=XmMa+(1Xm)Mb=0.04546.07+(10.045)18.016=19.278 kg/kmolMg=YmMa+(1-Ym)Mb=0.2746.07+(1-0.27)18.016=25.59 kg/kmol质量分率: Wa=XmMa/Ml=0.04546.07/19.278=0.1275 Wb=1-Wa=1-0.1275=0.87251/l= Wa/a+Wb
10、/b=0.1275/0.789+0.8725/1l=1.0341 kg/m3 P=105325Pav=PMg/RT=10532525.59/(8314 (273.15+93.16)v=0.8839 kg/m3 a=58.46 dyn/cm ,b=18.4 dyn/cm=X=0.68858.46+(1-0.688)18.4 =45.96 dyn/cm4.2塔径计算4.2.1精馏段:Ls=LMl/(3600l)=442.032*5/(3600845.1)=0.004 m/sVs=VMv(3600v)=543.3934.56/(36001.1952)=4.365m/s tm=83.285此温度下液体
11、的表面张力a=18.2 dyn/cm b=67.3 dyn/cm=Xma+(1-Xm)b=0.3418.2+0.6667.3=50.606两相流动参数:Flv=Ls/Vs(l/v) 0.5=0.00013/0.137(845.1/1.2424) 0.5=0.0247初设 板间距HT=0.5 m 清液层高度HL=0.06mHT-HL=0.44 m查得: Cf,20 = 0.093 液气气相负荷因子:Cf = (/20)0.20 Cf,20 =0.112气体气速:un,f = Cf (l-v)/v 0.5=0.112(845.1-1.2424) / 1.24240.5 = 2.919 m/s空速:
12、 un=0.7un,f=0.72.919=2.0433 m/s初估塔径:D=(Vs/(0.785un) 0.5=(0.137/(0.7852.0433) 0.5=0.292 m圆整为D=0.3 muf=vs/(0.785D2)=0.137/(0.7850.32)=1.939 m/s实际泛点百分率:uf/un,f=1.939/2.919=0. 66434.2.2提馏段:Ls=LMl/(3600l)=14.72319.278/(36001034.1)=0.000076 m/sVs=VMv(3600v)=11.75325.59/(36000.8839)=0.0945 m/stm=93.61此温度下液
13、体的表面张力a=18.2 dyn/cm b=67.3 dyn/cm=Xma+(1-Xm)b=0.04518.2+0.95567.3=65.091两相流动参数:Flv=Ls/Vs(l/v) 0.5=0.000076/0.0945(1034.1/0.8839) 0.5=0.0275初设 板间距HT=0.5 m 清液层高度HL=0.06mHT-HL=0.44 m查得: Cf,20=0.0947液气气相负荷因子:Cf=(/20) 0.20Cf,20=0.1199气体气速:un,f=Cf(l-v)/v 0.5=0.1199(1034.1-0.8839)/0.8839 0.5=4.099 m/s空速: u
14、n=0.7un,f=0.74.099=2.869 m/s初估塔径:D=(Vs/(0.785un) 0.5=(0.0945/(0.7852.869) 0.5=0.205 m圆整为D=0.25 muf=vs/(0.785D2)=0.0945/(0.7850.252)=1.926 m/s实际泛点百分率:uf/un,f=1.926/4.099=0.4704.3塔板的详细计算4.3.1.流动型式: 选取单溢流型4.3.2.堰的计算:A、精馏段:堰长取 lw=0.6D=0.60.3=0.18 m堰高 hw=0.04 mlh/lw2.5=0.000133600/0.18 2.5=34.046又 lw/D=
15、0.6 查得:E=1.03堰上清液高 how=0.00284E(Lh/lw) 2/3=0.00553 m清液层高度 hl=hw+how=0.04+0.00553=0.04553 m降液管底隙高 ho=hw-0.008=0.032 mB、提馏段:堰长取 lw=0.6D=0.60.25=0.15 m堰高 hw=0.04 mlh/lw2.5=0.000133600/0.15 2.5=53.705又 lw/D= 0.6 查得:E=1.03堰上清液高 how=0.00284E(Lh/lw) 2/3=0.00137 m清液层高度 hl=hw+how=0.04+0.00137=0.04137 m降液管底隙高
16、 ho=hw-0.012=0.028.塔板的布置(1)精馏段:选取碳钢为筛板的材料,板厚=4 mm,孔径do=6 mm取孔中心距t=18 mm,t/do=3开孔率=Ao/Aa=0.907/(t/do) 2=0.1008Ao开孔面积, Aa开孔区面积Af降液管截面积,At空塔截面积取外堰前的安定区:Ws1=0.02 m取内堰前的安定区:Ws2=0.02 m边缘区:Wc=20mm (D2.5m)lw/D=0.6r = D/2-Wc=0.3/2-0.02=0.13 mWd=0.10.3=0.03x=D/2-(Wd+Ws)=0.1An=2x(r2-x2) 0.5+r2arcsin(x/r)=0.046
17、3开孔区面积/塔板面积=0.0463/(0.7850.32)=0.6553 m2筛孔总面积 A0=An=0.04630.1008=0.004667 m2孔数:N=A0/u=0.004667/(0.7850.0062)=165.15取整:N=166 孔(2)提馏段:选取碳钢为筛板的材料,板厚=4 mm,孔径do=6 mm取孔中心距t=18 mm,t/do=3开孔率=Ao/Aa=0.907/(t/do)2=0.1008Ao开孔面积, Aa开孔区面积Af降液管截面积,At空塔截面积取外堰前的安定区:Ws1=20mm取内堰前的安定区:Ws2=20mm边缘区:Wc=20mm (D2.5m)lw/D=0.
18、6r = D/2-Wc=0.25/2-0.02=0.105 mWd=0.10.25=0.025x=D/2-(Wd+Ws)=0.08An=2x(r2-x2) 0.5+r2arcsin(x/r)=0.030开孔区面积/塔板面积=0.030/(0.7850.252)=0.7856m2筛孔总面积 A0=An=0.0300.1008=0.003024 m2孔数:N=A0/u=0.003024/(0.7850.0062)=107.006取整:N=108 孔.4校核4.4.1精馏段A.压降校核=4mm,do/=1.5, 查图得Co=0.78Hc干板压降,Co孔流系数下板阻力 Hc=0.051(v/l)(Uo
19、/Co)2Uo筛孔汽速,Uo=Vs/Ao=0.137/0.004667=29.355 Hc=01062(m液柱)Hl液层有效阻力,Fo气相动能因子Ua=Vs/(At-2Af)=0.137/0.063162=2.169Fa=Ua(pv)0.5=2.4176查表得=0.6Hl=(hw+how)=0.60.04553=0.02732m(液柱)总压降-Hp=Hl+Hc=0.1335(m液柱)0.6 kg液/kg气 合格B.液沫夹带的校核Ug-气体通过有效截面的面积的速率Ug=Vs/(At-Af)=2.0477 m/shf 板上鼓泡层高度 物系的起泡系数hf=hl/=0.07167 m , =0.6Ev
20、=(5.7E10-3/)(Ug/(Ht-hf) 3.2=0.01392 kg(液)/kg(汽) 0.1 kg(液)/kg(汽)不产生过量液沫夹带,合格.C.液泛校核Hd降液管液面高度,hd液相流经降液管的阻力hd=0.153(Ls/(lwho) 2=0.0000779 Hd=hw+how+hd+Hp=0.179 m , =0.6Hd/=0.2984 m0.44 m合格,不会产生液泛D.停留时间的校核 Af=0.003744 m2=AfHt/Ls=0.0037440.5/0.004=27.91 (35s) 合格E.漏液校核h-表面张力压头, Uom-漏点气速, Co-孔流系数h=4/9810ld
21、o=0.00407 (m液柱)do/=1.5查图得Co=0.78Uom=4.4Co(0.0056+0.13hl-h)l/v)0.56.381 m/sK=Uo/Uom=4.61.5 操作弹性大,不会发生严重漏液,合格。=4mm,do/=1.5, 查图得Co=0.78Hc-干板压降,Co-孔流系数下板阻力 Hc=0.051(v/l)(Uo/Co)2Uo筛孔汽速,Uo=Vs/Ao=0.0945/0.003024=31.25 Hc=0.0700(m液柱)Hl液层有效阻力,Fo气相动能因子Ua=Vs/(At-2Af)=2.153Fa=Ua(pv)0.5=2.0239查表得=0.6Hl=(hw+how)=
22、0.02482m(液柱)总压降-Hp=Hl+Hc=0.09482(m液柱)0.6 kg液/kg气 合格B.液沫夹带的校核Ug-气体通过有效截面的面积的速率Ug=Vs/(At-Af)=2.032 m/shf 板上鼓泡层高度物系的起泡系数 hf=hl/=0.04137m , =0.6 Ev=(5.7E10-3/)(Ug/(Ht-hf) 3.2=0.01453kg(液)/kg(汽) 0.1 kg(液)/kg(汽) 不产生过量液沫夹带,合格.C.液泛校核Hd降液管液面高度,hd液相流经降液管的阻力hd=0.153(Ls/(lwho) 2=0.0000501 Hd=hw+how+hd+Hp=0.1362
23、m , =0.6Hd/=0.2270m0.44 m 合格,不会产生液泛D.停留时间的校核 Af=0.0026m2=AfHt/Ls=0.00260.5/0.000076=17.105(35s) 合格E.漏液校核h-表面张力压头, Uom-漏点气速, Co-孔流系数h=4/(9810ldo)=0.00428 (m液柱)do/=1.5查图得Co=0.78Uom=4.4Co(0.0056+0.13hl-h)l/v)0.57.915 m/sK=Uo/Uom=3.9481.5 操作弹性大,不会发生严重漏液,合格。4.5负荷性能图4.5.1精馏段:A.液相下限线取how=0.006m E=1.04how=0
24、.00284E(3600ls/lw) 2/3ls=0.000145 m3/sB.液相上限线取=5 s =AfHT/LsLs=AfHT/=(0.50.003744)/5=0.0003744C.漏液线hl=hw+how=0.04+2.155ls2/3mUom=Vsmin/A0=Vsmin/0.2028Uom =4.4C0(0.0056+0.13hl-h)(l/v) 0.5Vsmin=0.0164.578+190.56ls2/3 0.5D.过量液沫夹带线:取ev=0.1 , E=1.04hf=2.5hl=0.1+5.388Ls2/3Ug=Vs/(AT-Af)=Vs/0.0669ev=(0.0057/
25、)Ug/(HT-hf) 3.2Vs=0.459-6.176Ls2/3E.液泛线:取 =0.6HT+hwHd ,Hd(0.4+0.04)/0.6=0.7333hd=0.153(Ls/(lwh0) 2=4611.55Ls2hc=0.051(Vs/A0C0) 2(v/l)=5.658Vs2hl=0.024+1.293Ls2/3hp=hc+hl=0.024+1.293Ls2/3+5.658Vs2Hd=0.7333=hl+hd+hp=0.1+5.388Ls2/3+4611.55Ls2+5.658Vs2 Vs2=0.112-0.952Ls2/3-815.05Ls24.5.2提馏段:A.液相下限线取how=
26、0.006m E=1.04how=0.00284E(3600ls/lw) 2/3ls=0.000121 m3/sB.液相上限线取=5 s =AfHT/Ls,Ls=AfHT/=(0.50.000076)/5=0.0000076C.漏液线hl=hw+how=0.04+2.434ls2/3 mUom=Vsmin/A0=Vsmin/0.003024Uom =4.4C0(0.0056+0.13hl-h)(l/v)0.5Vsmin=0.01047.628+370.19ls2/3 0.5D.过量液沫夹带线:取ev=0.1 , E=1.04hf=2.5hl=0.1+6.085Ls2/3Ug=Vs/(AT-Af
27、)=Vs/0.0465ev=(0.0057/)Ug/(HT-hf) 3.2Vs=0.151-2.291Ls2/3E.液泛线:取 =0.6HT+hwHd ,Hd(0.4+0.04)/0.6=0.7333hd=0.153(Ls/(lwh0)2=8673.47Ls2hc=0.051(Vs/A0C0)2(v/l)=7.835Vs2hl=0.024+1.4604Ls2/3hp=hc+hl=0.024+1.4604Ls2/3+7.835Vs2Hd=0.7333=hl+hd+hp=0.1+6.085Ls2/3+8673.47Ls2+73835Vs2 Vs2=0.081-0.7766Ls2/3-1107.02Ls2一)物料衡算1. 原料液量、残液量及加热蒸汽消耗量的计算(1)单位换算,将质量分率换算成摩尔分率原料液组成用xF表示。每位同学课程设计的进料浓度计算方法如下:aF=(30+班号后三位0.04+学号后两位0.1)%(质量分率)(2)计算混合物的平均分子量(3)作乙醇水物系的平衡曲线,确定回流比按设计指导书附录的平衡数据作x-y平衡曲线由塔顶馏出液组成(xD)点作平衡曲线最凹处的切线,其斜率为k=Rmin/(Rmin+1),进而求出Rmin确定回流比RR=(1.12) Rmin,,每位同学课程设计的回流比计算
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