新版化工原理习题答案(08)第八章 - - 气体吸收[1]

?qn,L??q?n,V?qn,L??q?n,V?Y1?Y2??m?A ??Y/m?X12?min?200??2.632 ???min47.5?1.6依题意

(qn,L/qn,V)min2.632??95.71%

m2.75y10.05(2)Y1???0.0526

1?y11?0.05?A? Y2?Y1?1??A??0.0526??1?0.9571??0.00226 X1?qn,Vqn,L?Y1?Y2??X2?47.5??0.0526?0.00226??0?0.0120

200 ?Y1?Y1?Y1*?0.0526?2.75?0.0120?0.0196 ?Y2?Y2?Y2*?0.00226?2.75?0?0.00226 ?Y??Y1??Y2?0.0196?0.00226?0.0080 3m?Y0.0196lnln10.00226?Y2 NOG? HOG?Y1?Y20.0526?0.00226??6.269 ?Ym0.00803Z5?m?0.798m NOG6.269由 HOG? Ω?qn,VKYa?qn,V

KYaHOG4Ω?π?47.5/360022 m?0.277m?43?10?221?0.9?0.798填料塔的直径为

D?4?0.277 m?0.594m 3.148. 在101.3 kPa及20 ℃的条件下,用清水在填料塔内逆流吸收混于空气中的氨气。已知混合气的质量流速G为600 kg/(m2·h),气相进、出塔的摩尔分数分别为0.05、0.,水的质量流速W为800 kg/(m2·h),填料层高度为3 m。已知操作条件下平衡关系为Y= 0.9 X,KGa正比于G 0.8而于W无关。若(1)操作压力提高一倍;(2)气体流速增加一倍;(3) 液体流速增加一倍,试分别计算填料层高度应如何变化,才能保持尾气组成不变。

解:首先计算操作条件变化前的传质单元高度和传质单元数 Y1?y10.05??0.0526 1?y11?0.05 5

Y2?y20.000526??0.000526 1?y21?0.000526 操作条件下,混合气的平均摩尔质量为 M?

?xMii???0.05?17??1?0.05??29??kg/kmol?28.4kg/kmol

qn,V?qn,L???600??1?0.05? kmol/(m2?h)?20.07kmol/(m2?h) 28.4mqn,V0.9?20.07800??1?0? kmol/(m2?h)?44.44 kmol/(m2?h) S???0.406 18qn,L44.44n,V Y1*?mX?mY0.406?Y??11??2?qqn,L0.052?60.?000?526

0.0211 ?Y1?Y1?Y1*?0.0526?0.0211?0.0315 ?Y2?Y2?Y2*?0.000526?0?0.000526 NOG??Y110.0315ln1?ln?6.890 1?S?Y21?0.4060.000526 HOG?Z3?m?0.435m NOG6.890 (1)pt??2pt m?E ptptmm? pt?2?S0.406??0.203 22 m?? S??m?qn,Vqn,L 若气相出塔组成不变,则液相出塔组成也不变。所以 ?Y1??Y1?Y1?*?0.0526??0.0211?0.0421 ?Y2??Y2?Y2?*?0.000526?0?0.000526

12?? NOG HOG??Y?110.0421ln1?ln?5.499 1?S??Y2?1?0.2030.000526qn,VKYa??qn,VKGap总?

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HOG??qn,VH0.435?OG?m?0.218m ??KGap总22m 1.199?? Z??H?5.499?mOGNOG?0.218 即所需填料层高度比原来减少1.801m。

?Z?Z??Z?(1.199?3)m??1.801m

??2qn,V (2)qn,V S???mqn,VL?2S?2?0.406?0.812

若保持气相出塔组成不变,则液相出塔组成要加倍,即

??2X1 X1故

*??1?Y?Y1??Y1?Y1?Y1?mX??SY?Y1?1?2?0.052?60.8??120.?05260.?0?00526

0.0103 ?Y2??Y2?Y2?*?0.000526?0?0.000526 NOG?? HOG??Y?110.0103ln1?ln?15.82 1?S??Y2?1?0.8120.000526qn,VKYa??????qn,VKGaP??qqn,V0.8n,V?q0.2n,V

?q? HOG???n,V?q?n,V0.2HOG?20.2?0.435m?0.500m

?NOG??0.500?15.82m?7.910m Z??HOG ?Z?Z??Z?(7.910?3)m?4.910m 即所需填料层高度要比原来增加4.910 m。

??2qn,L (3) qn,L S??mqn,VS0.406???0.203 ?qn,L22??Y1?Y2?*1 NOG???ln??1?S???S?

1?S??Y2?Y2?*? ?10.0526?0??ln??1?0.203??0.203??5.497

1?0.203?0.000526?0? W对KGa无影响,即qn,L对KGa无影响,所以传质单元高度不变,即

??HOG?0.435m HOG?NOG??0.435?5.497m?2.391m Z??HOG ?Z?Z??Z?(2.391?3)m??0.609m 即所需填料层高度比原来减少0.609 m。

9. 某制药厂现有一直径为1.2 m,填料层高度为3 m的吸收塔,用纯溶剂吸收某气体混合物中的溶质组分。入塔混合气的流量为40 kmol/h,溶质的含量为0.06(摩尔分数);要求溶质的回收率不低于95%;操作条件下气

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液平衡关系为Y = 2.2X ;溶剂用量为最小用量的1.5倍;气相总吸收系数为0.35 kmol/ (m2·h)。填料的有效比表面积近似取为填料比表面积的90%。试计算(1)出塔的液相组成;(2)所用填料的总比表面积和等板高度。

解:(1)Y1?y10.06??0.0638 1?y11?0.06 Y2?Y1?1??A??0.0638??1?0.95??0.00319 惰性气体的流量为

qn,V?40?(1?0.06)kmol/h?37.6kmol/h

?qn,L??q?n,V? ???m?A?2.2?0.95?2.09?min?q? X1?n,Lmin?2.09?37.6kmolh?78.58kmolh

qn,L?1.5?75.58kmolh?117.9kmolh

qn,Vqn,L?Y1?Y2?37.6?X2?0.0638?0.009?0???31?117.9 0.0193(2)?Y1?Y1?Y1*?0.0638?2.2?0.0193?0.0213 ?Y2?Y2?Y*?0.0031?92 ?Ym?2.?2?0 003190.?Y1??Y20.0213?0.00319??0.00954 ?Y10.0213lnln0.00319?Y2Y1?Y20.0638?0.00319??6.353 ?Ym0.00954 NOG? HOG?由 HOG?Z3?m?0.472m NOG6.353qn,VKYa?qn,V

填料的有效比表面积为

a?HOGKY??37.6m2/m3?201.35m2/m3 20.472?0.35?0.785?1.2填料的总比表面积为

at?NT201.3523m/m?223.72m2/m3 0.9S?1由 NOG?lnS

S?mqn,Vqn,L?2.2?37.6?0.702

117.96.353?(0.702?1)?5.351

ln0.702由 Z?HET? PTNNT?填料的等板高度为

3m?0.561m

5.351 10. 用清水在塔中逆流吸收混于空气中的二氧化硫。已知混合气中二氧化硫的体积分数为0.085,操作条件下

HETP?

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