化学反应工程第二版课后答案

1dnAnA?nA0?1?xA?V?V0?1??AxA?Vdt1?1?211?A???2yA0???A??0.511?34cA0dxA2 ?rA??kcAcB?1?0.5xA?dt?rA??cA?cA0cB?1?xA1?0.5xAnB?nB0?2nA0xAnBnB0?2nA0xA3nA0?2nA0xA3?2xA???cA0VV0?1?0.5xA?V0?1?0.5xA?1?0.5xA2?3?2xA?dxA2????kcA1?x 0A???dt?1?0.5xA?

17. 已知常压气相反应

k1???2A?B?R?S ??k2abrs动力学方程为?rA?k1cAcB?k2cRcS,试用下列三种方式表达动力学方

程:

(1)组分分压; (2)组分摩尔分率;

(3)组分初始浓度和A的转化率。 解

pA?cARTabrspApBpRpS?rA?kcc?kcc?k1?k?RT?a?b2?RT?r?spA?P总yAab1ABrs2RSabrspApBpRpSab?P总??rA?k1?k?kyy??21ABa?br?s?RT??RT??RT?a?b

?P??k2yy?总??RT?rRsSr?s 25

cA?cA0cR?1?xA1??AxAcB?cB0?0.5cA0xA1??AxAcS0?0.5cA0xA1??AxAbcR0?0.5cA0xA1??AxAacS??1?xA??rA?k1?c?A01??x??AA???cR0?0.5cA0xA???k2??1??x?AA??r?cB0?0.5cA0xA????1??x?AA??s

?cS0?0.5cA0xA????1??x?AA??

18. 高温下二氧化氮的分解为二级不可逆反应。在平推流反应器中101.3kPa

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下627.2K时等温分解。已知k=1.7mkmols,处理气量为120mhr(标准状态),使NO2分解70%。当(1)不考虑体积变化;(2)考虑体积变化时,求反应器的体积。 解

2NO2?N2?2O22?rA?kcA,k?1.7m3kmol?1s?1,T?627.2K,V0?120Nm3hr?1 xA?0.70p?0.1013kPa,(1) 恒容过程

0.7VR?FA0?FA0?0dxA22kcA0(1?xA)120?1.488?10?3kmol?s?122.4?3600

101.3cAS??0.01943kmol?m?38.314?627.21.488?10?3xA3VR1???5.41m1.7?0.0194321?xA(2) 变容过程

26

VR2?FA00.71??AxAdxA2?0kcA01?xA2?1?2?0.5,2FA02?0kcA00.7?A?VR2?yA0?1,2?A?0.5?1?0.52?1?0.5xA?FA00.7??0.5?0.5xA?1.5????dx?dxA?1?x?Akc2?0???1?xAAA0????2

??0.25FA00.7?30.25FA00.7?96??????1dx???1A222??????dxA00kcA01?xkc(1?x)1?xAA0AA?????0.25FA0?9xA3????6ln(1?x)?x?8.382mAA2?1?x?kcA0A??x?0.7A

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19. 均相气相反应A→3P,服从二级反应动力学。在0.5MPa、350℃和V0=4mhr

下,采用—个25mm内径,长2m的实验反应器,能获得60%转化率。设

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计一个工业平推流反应器,当处理量为320mhr,进料中含50%A,50%惰性物料时,在2.5MPa和350℃下反应,为获得80%的转化率.求需用25mm内径,长2m的管子多少根?这些管子应并联还是串联? 解

(1) 求速率常数k

pA0500??0.0965kmol?m?3RT8.314?623.15πVR??0.0252?2?9.817?10?4m34

3?1?A??2yA0?1?A?211?xA222?rA?kcA?kcA0()1?2xAcA0? 27

2??cAdxA1A0?x02??xA??1?2xA?0?kc2?1?xA?kcA0?1?x?A??dxA0???1?2x?A???1?kc?4xA?12ln?1?xA??9?9??A0??1?xA??

?1?kc?4?0.6?12ln?1?0.6??9?9??A0?1?0.6??1kc?4.905A0?VR9V?.817?10?4??2.454?10?4hr?0.8836s04k?4.905?1?4.905?0.0965?57.52m3?ckmol?1s?1A00.8836(2)求反应器体积和管数

yA0?0.5,?A?yA0?A?0.5?2?2,xA?0.8V0?320m3hr?1?0.08889m3s?1FpA0V0RT?0.5?2500?0.08889A0?8.314?673.15?0.01985kmol?s?1cA0?pA0?0.5?2500?0.2334kmol?m?3RT8.314?623.15VxAfdxAR?F?FxAfdxAxAfdxAA0?0?rA0?2A0kc2?FA0A?0kc2??1?xA?A0??1?x?A??2?FA0kc2A0?xAf??1?xA?0??1?x???dxAA?FA0xAf?kc2A0?0??44???1?x??1?dxA?21?xA?? 28

?F?4????A0?4ln1?x?xAA?2??kcA1?x0?A?0?0.80.01985?4????4ln1?0.8?0.8?4??

57.52?0.23342?1?0.8??0.06564m30.06564N??67?49.817?10管子的串并联要从流体阻力和流型考虑,在保持平推流的前提下尽量并联。

2

20. 有一气相分解反应,其化学反应式为A→R+S,反应速率方程为?rA=kcA,

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反应温度为500℃。这时测得的反应速率常数为k=0.25mkmols。反应在内径为25mm、长为1m的管式反应器中进行,器内压强维持在101.3kPa

-1

(绝),进料中仅含组分A,当其转化率为20%,空间速度为45hr(反应条件下的计算值)。试求反应条件下的平均停留时间和空间时间。 解

?A?yA0cA0??A?1?2?1?11cA?cA01?xA1??AxApA0101.3??0.01576kmol?m?3RT8.314?(273.15?500)

??VRVONT273.15??0??0.007851hr?28.26sV0SVV0SVT45??273.15?500?xAf0t?cA0????dxA1?(?rA)(1??AxA)kcA0?xAf01?xAdxA2?1?xA?1xAf?21???dxA?2???0kcA0??1?xA?1?xA??1?22???????ln1?x??ln1?0Af??kcA0?1?xAf1?0?

1?2??ln?1?0.2??2??0.25?0.01576?1?0.2??70.3s 29

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