??01=
⑵提馏段:
????11.72508
==10.52??╱?? ??00.164??02=
????21.82151
==11.11??╱?? ??00.1644.4流体力学核算
(1)塔板压降
1.精馏段 ⑴干板阻力 因为Φ≤15%,
????=
查图得:C0=0.5 (1)精馏段:
??0×10000.004×1000
==1.33 ??3???1
??012????110.521.02
=0.051()=0.051()=0.0282
??0????10.5816.662
(2)提馏段:
???2
??022????211.1120.75
=0.051()=0.051()=0.0203
??0????20.5931.46⑵板上充气液层阻力 (1)精馏段:
????1
????11.72508===1.91??╱?? ????1?????1.1304?0.2261????1=????1√????1=1.91×√1.02=1.93
由充气系数关联图查得:β1=0.564
23
图4-4充气系数关联图
???1=??1????=0.564×0.07=0.039??
(2)提馏段:
????2
????21.82151===2.01??╱?? ????2?????1.1304?0.2261????2=????2√????2=2.01×√0.75=1.74
由充气系数关联图查得:β2=0.573
???2=??2????=0.573×0.07=0.04??
⑶液体表面张力所造成的阻力 (1)精馏段:
???1=
4??1×0.0014×35.34×0.001
==0.0044
????1×9.81??0816.66×9.81×0.004
???1=???1+???1+???1=0.0282+0.039+0.0044=0.072??
气体通过每层塔板压降:
24
??????1=???1????1??=0.072×816.66×9.81=576.82????
△Pp=576.82Pa<0.7kPa (2)提馏段:
???2=
4??2×0.0014×55.9×0.001
==0.0061
????2×9.81??0931.46×9.81×0.004???2=???2+???2+???2=0.0203+0.04+0.0061=0.066??
气体通过每层塔板压降:
??????2=???2????2??=0.066×931.46×9.81=603.08????
△Pp=603.08Pa<0.7kPa
(2)液面落差
对于筛板塔,液面落差很小,且本设计的塔径和液流量均不大,故可忽略液面落差的影响。
(3)雾沫夹带
???=2.5????=2.5×0.07=0.18??
(1)精馏段:
????1
3.23.25.7×10?6????15.7×10?61.91
=()=()=0.0844????液╱????╱
??1????????35.340.45?0.180.0844(kg液/kg气)<0.1(kg液/kg气) (2)提馏段:
????2
3.23.25.7×10?6????25.7×10?62.01=()=()=0.0629????液╱????╱
??2????????55.90.45?0.180.0629(kg液/kg气)<0.1(kg液/kg气) 故设计液沫夹带量e_v在允许范围内。
(4)漏液
对于筛板塔,漏液点气速的计算
25
(1)精馏段:
=4.4??0√(0.0056+0.13???????1)×(
=6.32??╱??
????1
??0??????1
????1
)=4.4×0.5√(0.0056+0.13×0.07?0.0044)×(
816.661.02
)
筛板稳定系数:
??1=
1.66>1.5 (2)提馏段:
??01??0??????1
=
10.52
=1.66 6.32??0??????2=4.4??0√(0.0056+0.13???????2)×(
????2
=7.19??╱??
????2
)=4.4×0.5√(0.0056+0.13×0.07?0.0061)×(
931.460.75
)
筛板稳定系数:
??2=
1.55>1.5
??02??0??????2
=
11.11
=1.55 7.19介于1.5-2.0之间,故在设计负荷下不会发生明显漏液现象。
(5)液泛
为防止塔内发生液泛,降液管内液层高度H_d<φ(H_T+hW),安全系数φ=0.5 (1)精馏段:
液体通过降液管的压头损失(不设进口堰)
????1=??(????+???1)=0.5×(0.45+0.064)=0.257?? ???1
????120.001192
=0.153()=0.153()=0.0026??
?????011.02×0.009????1=???1+???1+????=0.072+0.0026+0.07=0.1446
0.1446m<0.257m (2)提馏:
????2=??(????+???2)=0.5×(0.45+0.059)=0.254??
26
???2
????220.003062
=0.153()=0.153()=0.0026??
?????021.02×0.023????2=???2+???2+????=0.066+0.0026+0.07=0.1386
0.1386m<0.254m
故在设计负荷下不会液泛。
根据以上塔板的各项流体力学核算,可认为精馏段、提馏段塔径及各工艺尺寸是合适的。
4.5塔板负荷性能图
(1)雾沫夹带线
以ev=0.1kg液/kg气为限,
5.7×10?6????由????=()
????????????
⑴精馏段:
3.2;
????1
????????1
===1.11????1 ?????????1.1304?0.22612323?????
2??????3600????1×0.012
=0.0442()=0.0442()=0.54????13
????1.022
3
???=2.5???=2.5×(???+?????)=2.5×(0.064+0.54????1
?6
)=0.16+1.35????1
3.2
23
5.7×10????=(1.11×
35.34×0.001????2
(0.45?(0.16+1.35????2
23
2))3)=0.1
整理得:????1=1.95?(9.07????1
)
⑵提馏段:
????2=
????????2
==1.11????2
?????????1.1304?0.226127
化工课程设计 - 图文
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