每层塔板的开孔数n2?1.1551.155?0.532A??3135(孔) a220.014t222?d??1? 每层塔板的开孔率?2?0.907?0??0.907???0.116(φ应在5~15%,
?2.8??t?故满足要求)
每层塔板的开孔面积A02??2Aa?0.0617m2
气体通过筛孔的气速uo2?Vs/Ao2?0.612/0.0617?9.92m/s
六.塔板上的流体力学验算
1.塔板压降
hp?hc?hl?hσ 1.1气体通过干板的阻力压降
hc
由do/δ?5/3?1.67 查图,得Co?0.772
?uo??V1?11.40?2.86???0.051?0.0376m液柱 精馏段:hc1?0.051???C???0.772?846.8?o?L1?uo??V2?9.92?3.46???0.051?0.0315m液柱 提馏段:hc2?0.051???C??0.772924.4???o?L22222式中Co为孔流系数。
1.2气体通过板上液层的压降hl
气体通过有效流通截面积的气速ua,对单流型塔板有:
ua?Vs0.612??0.840m/s
AT?Af0.785?0.0567精馏段:动能因子Fa?ua?V?0.8402.86?1.421kg1/2/(s?m1/2) 查图,得?1?0.61
故hl1??1?hw1?how1???1hL?0.61?0.06?0.0366m液柱 提馏段:动能因子Fa??ua?V2?0.8403.46?1.562kg1/2/(s?m1/2) 查图,得?2?0.58
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故hl2??2?hw1?how1???2hL?0.58?0.06?0.0348m液柱 1.3气体克服液体表面张力产生的压降hσ
4?L14?20.77?10?3精馏段:h?1???0.002m液柱
?L1gdo846.8?9.81?0.005提馏段:h?24?L24?19.03?10?3???0.00168m液柱 ?L2gdo924.4?9.81?0.0051.4气体通过每层筛板的压降(单板压降)hp和Δpp
精馏段:hp1?hc1?hl1?h?1?0.0376?0.0366?0.002?0.0762m
?pp1??L1ghp1?846.8?9.81?0.0762?633Pa?0.7kPa(设计允许值) 提馏段:hp2?hc2?hl2?h?2?0.0315?0.0348?0.00168?0.068m
?pp2??L2ghp2?924.4?9.81?0.068?616.6Pa?0.7kPa
2.液沫夹带量ev的验算
精馏段:hf?2.5hL?2.5?0.06?0.15m
3.25.7?10?6?ua?5.7?10?6?0.840?e?????3?? V1?L1?H?h20.77?100.40?0.15?? ?Tf???0.0133kg液/kg气?0.1kg液/k气g(满足要求)3.2提馏段:hf?2.5hL?2.5?0.06?0.15m
eV23.25.7?10?ua?5.7?10?6?0.840??????3???L2?H?h19.03?100.40?0.15?? ?Tf???0.0145kg液/kg气?0.1kg液/k气g(满足要求)?63.2故在本设计中液沫的夹带量在允许的范围内
3.漏液的验算
3.1精馏段:漏液点的气速uom1
uomin1?4.4Co
?0.0056?0.13hL?h?1??L1/?V1?4.4?0.772?0.0056?0.13?0.06?0.002?846.8/2.86
?6.241m/s 实际孔速u01?11.40m/s?u0,min1
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筛板的稳定性系数K1?uo111.40??1.827?1.5 uom16.2413.2提馏段:漏液点的气速uom2
uomin2?4.4Co
?0.0056?0.13hL?h?2??L2/?V2?924.4/3.46 ?4.4?0.772?0.0056?0.13?0.06?0.00168?6.01m2/s 实际孔速u02?9.92m/s?u0,min
筛板的稳定性系数K2?故在本设计中无明显漏液。
uo29.92??1.65?1.5 uom26.0124.液泛的验算
为防止降液管发生液泛,应使降液管中的清液层高度Hd???HT?hw? 苯-氯苯物系属一般物系,取??0.5,则 精馏段:
??HT?hw1??0.5??0.4?0.0528??70.22m6 而 Hd?hp?hL?hd , 板上不设进口堰,
hd?0.153?u?o'2?0.153?0.15??0.00344m液柱
2Hd1?0.0762?0.06?0.00344?0.1396m液柱 提馏段:
??HT?hw2??0.5??0.4?0.041?6?0.22m1
Hd?0.068?0.06?0.0034?40.131m4液柱
Hd???HT?hw?成立,故在本设计中不会发生液泛现象。
通过流体力学验算,可认为精馏段塔径及塔板各工艺结构尺寸合适,若要做出最合理的设计,还需重选HT及hL,进行优化设计。
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七、塔板负荷性能图
1.漏液线(气相负荷下限线)
精馏段:
2/3??????Lh12.84????E??h?0.0056?0.13?hw1??1??L1/?V1?l?1000??w????????VS,min?4.4C0A01 Vs,min?4.4?0.772?0.0537?2/3????3600L??s???0.0056?0.130.05287?0.00284?1?????0.002?846.8/2.86?0.66????????/3整理得: Vs.min?3.1390.01047?0.114L2 s
在操作范围内,任取几个Ls值,依式算出对应的Vs值列于下表:
Ls,m3/s Vs,m3/s 0.0005 0.3320 0.0015 0.3433 0.0030 0.3557 0.0045 0.3658 0.0060 0.3745 依据表中数据作出漏液线1 提馏段:
VS?,min?4.4C0A022/3??????Lh22.84????E??h?0.0056?0.13?hw2???L2/?V2?2??1000?lw????????? Vs?,min?4.4?0.772?0.0617?2/3?????3600L??s?0.00168?0.0056?0.13?0.0416?0.00284?1???924.4/3.46????0.66????????
?2/3 整理得: Vs?.min?3.4260.00933?0.114Ls?值,依式算出对应的Vs?值列于下表: 在操作范围内,任取几个Ls?,m3/s LsVs?,m3/s 0.0005 0.3434 0.0015 0.3564 0.0030 0.3706 0.0045 0.0.3821 0.0060 0.3920 依据表中数据作出漏液线1?
2.液沫夹带线
以eV?0.1kg液/kg气为限,求Vs?Ls关系如下:
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5.7?10??ua由 eV??L??HT?hf?6?? ??3.2式中:ua?VsVs??1.373Vs
AT?Af0.785?0.0567 hf?2.5hL?2.5?hw?how?
hw1?0.0528 7 hw2?0.041 62.84?3600Ls? how??1???10000.66??故
2/3?0.88Ls
2/3
2/32/3hf1?0.132?2.2Ls2/32/3hf2?0.104?2.2LsHT?hf1?0.268?2.2LsHT?hf2?0.296?2.2Ls3.2
将已知数据代入式得:
?Vs5.7?10?1.373精馏段:ev??/3?20.77?10?3?0.268?2.2L2s?/3 Vs?1.233?10.12L2s
?6?0.1
在操作范围内,任取几个Ls值,依式算出对应的Vs值列于下表:
Ls,m3/s Vs,m3/s 0.0005 1.169 0.0015 1.100 0.0030 1.022 0.0045 0.9572 0.0060 0.8988 由上表数据即可作出液沫夹带线2
5.7?10?6提馏段:ev?19.03?10?3?1.373?Vs?2/3?0.296?2.2Ls??3.2?0.1
?2/3 Vs??1.325?9.848Ls?值,依式算出对应的Vs?值列于下表: 在操作范围内,任取几个Ls?,m3/s LsVs?,m3/s 0.0005 1.263 0.0015 1.196 0.0030 1.120 0.0045 1.057 0.0060 0.9998 由上表数据即可作出液沫夹带线2?
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