气相密度：
????1
????1??28.859×273.15
===1.02????╱╱ 22.4×(??+??1)22.4×(273.15+73.35)在提馏段：液相密度ρL2：
????2
??2????0.0631×32.04
===0.107 ??2????+????(1???2)0.0631×32.04+18.01×(1?0.0631)????2
11
===931.46????╱╱ ????21?????20.1071?0.107+??????2+??????2723.5443964.6721气相密度：
????2
????2??22.406×273.15
===0.75????╱╱ 22.4×(??+??2)22.4×(273.15+90.91)(3)相对挥发度的求取
精馏段相对挥发度:
??1=
提馏段相对挥发度:
??1(1???1)??1(1???1)
=
0.7733×(1?0.4886)
=3.57
0.4886×(1?0.7733)0.3133×(1?0.0631)
??2===6.77
??2(1???2)0.0631×(1?0.3133)全塔相对挥发度:
??2(1???2)
??1+??23.57+6.77??===5.17
22(4)粘度的求取
精馏段t1=73.35℃,利用插值法： μA1:
73.35?6080?60
= ????1?0.3440.277?0.344μA1=0.299mpa.s μB1:
8
73.35?7080?70
= ????1?0.40610.3565?0.4061μB1=0.389mpa.s
提馏段t2=90.91℃,利用插值法： μA2:
90.91?80100?80
= ????2?0.2770.228?0.277μA2=0.25mpa.s μB2:
90.91?90100?90
= ????2?0.31650.2838?0.3165μB2=0.314mpa.s 精馏段粘度:
??1=????1??1+????1(1???1)=0.299×0.4886+0.389×(1?0.4886)=0.345??????.?? 提馏段粘度:
??2=????2??2+????2(1???2)=0.25×0.0631+0.314×(1?0.0631)=0.31??????.??
(5)表面张力计算
塔顶液相平均表面张力的计算： 由tD=64.677℃,查表得： σDA:
64.677?6080?60
=
???????17.3315.04?17.33σDA=16.79mN╱m σDB:
64.677?6070?60
=
???????66.0764.3?66.07σDB=65.24mN╱m 塔顶表面张力：
9
??????=??????????+??????(1?????)=16.79×0.9823+65.24×(1?0.9823)=17.65????╱?? 进料板液相平均表面张力的计算： 由tF=82.019℃,查表得： σFA:
82.019?80100?80
=
???????15.0412.8?15.04σFA=14.81mN╱m σFB:
82.019?8090?80
=
???????62.660.7?62.6σFB=62.22mN╱m 进料板表面张力：
??????=??????????+??????(1?????)=14.81×0.1941+62.22×(1?0.1941)=53.02????╱?? 塔底液相平均表面张力的计算： 由tW=99.802℃,查表得： σWA:
99.802?80100?80
= ???????15.0412.8?15.04
σWA=12.82mN╱m σWB:
99.802?90100?90
=
???????60.758.8?60.7σWB=58.84mN╱m 塔底表面张力：
??????=??????????+??????(1?????)=12.82×0.0011+58.84×(1?0.0011)=58.79????╱??
精馏段液相平均表面张力：
??????
??????+??????17.65+53.02
===35.34????╱??
2210
提馏段液相平均表面张力：
??????
??????+??????58.79+53.02===55.9????╱??
223.3塔板数的确定
(1)理论塔层数NT的求取
①求最小回流比及操作回流比 本设计为泡点进料:q=1
根据y=q/(q-1)x-(xF/(q-1))；y=ax/(1+(a-1)x) 可得： xq=0.1941
????=
??????5.17×0.1941
==0.555
1+(???1)×(????)1+(5.17?1)×0.1941??????????????????
故最小回流比：
????????=
取操作回流比：
=
0.9823?0.555
=1.184
0.555?0.1941??=??????????=1.5×1.184=1.776
②求精馏塔的气、液相负荷
??=????=1.776×79.07=140.428????????╱?
??=(??+1)×(??)=(1.776+1)×79.07=219.498????????╱? ??′=??+????=140.428+1×401.99=542.418????????╱?
??′=??+(???1)×(??)=219.498+(1?1)×401.99=219.498????????╱? ③求操作线方程 精馏段操作线方程：
????+1=
提馏段操作线方程：
??????
????+=0.64????+0.3539 ??+1??+111
????+1=
相平衡方程：
??′????
???????=2.4712?????0.00162
??′?????′?????????== ???(???1)×(??)5.17?4.17??
由逐板法可求：
总理论板层数13板（包括再沸器） 其中进料板在第5板
精馏段理论板数????1=4╱ 提馏段理论板数????2=8╱
(2)实际板层数的求取
精馏段实际板数： α1=3.57,μ1=0.345mpa.s
??1=0.49(??1??1)
?0.245
=0.49(3.57×0.345)?0.245=0.4656
????1
提馏段实际板数： α2=6.77,μ2=0.31mpa.s
????14===9╱ ????10.4656??2=0.49(??2??2)
?0.245
=0.49(6.77×0.31)?0.245=0.4086 ????28
==20╱ ????20.4086????2=
全塔所需实际塔板数：????=????1+????2=9+20=29╱ 全塔效率：????=
????13?1100%=100%=41% ????29╱╱╱╱╱╱╱╱╱10╱╱
12
化工课程设计 - 图文
