北京化工大学2010——2011学年第一学期
《化学反应工程》（双语）期末考试试卷
课程代码
C
H
E
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T
班级：          姓名：          学号：        分数：       
题号
一
二
三
四
五
六
七
reaction diffusion总分
得分
A. Choose the most suitable answer in the four choices. (3 points for each one, 15 points in total)
1. For a first order irreversible reaction, which one of four reaction conditions is the most temperature sensitive?                                                                  (      )
A
Large activation energy, high temperature
B
Small activation energy, high temperature
C
Large activation energy, low temperature
D
Small activation energy, low temperature
2. The reaction, its reaction time to reach 50% conversion is free from initial concentration, what reaction it is?                                (      )
A
First order irreversible
B
First order reversible
C
Second order irreversible
D
Second order reversible
3. Reversible reactions, if the forward one is an elementary reaction, the backward one will (      )
A
Be an elementary reaction too.
B
Not be an elementary reaction.
C
Ether elementary reaction or non-elementary reaction.
D
There is not elementary reversible reaction at all.
4. There is a first order irreversible reaction processed in a mixed flow reactor.  For some reasons, the reactor will be replaced by two equal-sized mixed flow reactors, while the total size is as same as the original one.  If they are operated in parallel, what will happen with the conversion? (      )
A
Keep unchanged
B
Goes up
C
Goes down
D
Not sure
5. The relationship between dispersion coefficient Ddisp and diffusion coefficient Ddiff is that  (    )
A
Ddisp is always bigger than and at least the same as Ddiff
B
Ddisp is always smaller than and at least the same as Ddiff
C
Ddisp and Ddiff are almost the same
D
there isn't relationship between Ddisp and Ddiff
B. Consider the following first order decompositions with rate constants as shown
If a colleague reports that CS=0.2CA0 in the exit stream of a plug flow reactor, what can you say about the concentration of the other reactor components, A, R, T, and U in the exit stream? (15 points)
C. For a mixed flow reactor operating at steady-state, and with a stream of constant density, what fraction of the exit stream(15 points)
(a) has been in the tank for a time greater than?
(b) is of age less than 2?
(c) has been in the tank between and 3?
D. A first order liquid reaction proceeding in a mixed flow reactor with 50% conversion, what will be the conversion if the reactor size is trebled and all else remains unchanged? (15 points)
E. Calculating the space-time in a plug flow reactor for gaseous parallel reactions. The inlet flow contains 50%A and 50% inert.  The conversion in outlet stream is 90%.(10 points)
F. My boss decided to do something to improve the low conversion (XA=0.80) of our first-order solid-catalyzed liquid-phase reaction.  Instead of ordering more of the expensive catalyst to fill the half-empty reactor, he decided to save money by adding some tricky pipin
g to the present vertical packed bed reactor.  When I saw what the mechanics were putting together for him, I told him that it didn’t seem right. I could sense right away that my saying this annoyed him, but all he said was, “All right, young man. Why don’t you tell me what conversion to expect with this arrangement?” Please do this. (15 points)
G. A packed bed reactor converts A to R by a first order catalytic reaction, A→R. With 9 mm pellets the reactor operates in the strong pore diffusion resistance regime and gives 63.2% conversion. If these pellets were replaced by 18 mm pellets (to reduce the pressure drop), how would this affect the conversion?  (15 points)

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