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PRIFYSGOL ABERTAWE
SWANSEA UNIVERSITY
College of Engineering
ALTERNATIVE EXAM
MAY/JUNE 2020
EG-204
REACTOR DESIGN I
YEAR 2
Time allowed: 2 days
Answer ALL questions
Examiner: Dr D.L. Oatley-Radcliffe
Please insert any standard constants here:-
1 bar = 1×105 Pa, 1 cP = 1 mPa.s, 1 m3 = 1000 L,
RMM: C=12, H=1, S=32, O=16; R = 8.314 J mol-1 K
-1
.
NOTE: This exam is ‘open book’, any materials may be used.
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Use the following information in all questions as necessary:
Figure 1: Chemical synthesis of Tertbutylfluroaminoacid.
Molecular weights: A = 311 g mol-1
, B = 207 g mol-1
, C = 419 g mol-1
,
Tertbutylfluroaminoacid (C) is produced by the reaction of tertbutylaminoester (A) and
flurobromobenzene (B) according to the following chemical synthesis:
Tertbutylaminoester (1wt) is dissolved in ethyl acetate (5vol) and set to stir for 30 min.
Flurobromobenzene (1.1eq, 1vol) is then added and the reaction mixture is elevated to
75 °C and allowed to react. Post reaction, the mixture is cooled and a solution of 0.1M
KOH is added (10vol). The resultant mixture is stirred vigorously for 30 min and then left
to settle. The bottom layer is then removed, stored and recharged to the vessel following
removal of the top layer. Concentrated HCl (1.5eq, 1vol) is added to instantly form
Tertbutylfluroaminoacid. The resultant solution is concentrated by distillation to 6vol and
then cooled to 25 °C and allowed to stir for 30 minutes, then cooled further to 15 °C and
stirred for 2 hours. The resultant slurry is harvested by filtration, the cake is washed with 3
x 2vol washes of propanol and the resultant solid is dried in vacuum overnight. Yield ~86%
theory.
1. Given the process outlined above:
(a) Draw a box diagram of the process and label the diagram with as much process
information as possible.
[20 marks]
(b) The harvested solids in the process are washed with propanol, why?
[5 marks]
[Total 25 marks]
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2. Given the information below:
Figure 2: Production area Reaction Vessels (RV) available for the chemical synthesis.
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The production area is on 3 floors; with vessels RV1201 and RV1202 on the top floor,
RV1203 and RV1204 on the middle floor, with a filter pan and drying oven on the
bottom floor. Transfer is possible between each of the vessels; in the vertical
downwards direction this will be via gravity, in the sideways direction via pressure push
and vacuum pull, and in the vertical upwards direction using a diaphragm pump.
(a) The process is intended to be run using vessels RV1201 for the main reaction,
RV1204 for the liquid-liquid extraction, acidification and distillation, and
RV1203 for the crystallisation. What will be the maximum and minimum batch
size that can be accommodated in the equipment as defined? Base your answer
on the product material.
[20 marks]
(b) Are RV1201, RV1203 and RV1204 suitable vessels for the intended duty?
[5 marks]
[Total 25 marks]
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3. The primary chemical reaction in the synthesis is bimolecular second order.
(a) Show by mass balance, that the reaction time for this chemical reaction can be
represented as:
= ∫

(0 − )(0 − )

0
where
is the batch reaction time, the number of moles of reagent converted to
product, is the reaction rate constants for the forward and reverse reactions
respectively, the concentration of material A (similarly for B) and the suffix 0 and
represent the start and end time of the batch reaction.
[5 marks]
(b) Given the conditions for the primary reaction outlined previously and the
second order rate constant for the reaction is = 2.47 x10-4 m3 mol-1
s
-1
.
Calculate the time required (in hours) to achieve 90% conversion.
[15 marks]
(c) Is this a sensible reaction time? How might the reaction time be improved?
[5 marks]
[Total 25 marks]
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4. Given all of the information thus far and the fact that the distillation process requires
two hours to complete. Ignoring the filtration, washing and drying process, estimate:
(a) The batch time for the chemical synthesis.
[10 marks]
(b) The cycle time for the chemical synthesis.
[2 marks]
(c) If all the reaction vessels were to be used in the synthesis, what would be the
minimum batch time and cycle time for the process? Explain your reasoning.
[8 marks]
[Total 20 marks]
5. This process is intended to be scaled-up to the production factory in order to produce
25 tonnes of product in a three-month campaign. Assuming that a 4 pot process is used
due to the primary reaction time and the plant works at a two eight hours per day shift
cycle, but with no weekend working:
(a) What size reaction vessels should be used?
[10 marks]
(c) Should any changes be made to the reaction vessels on scale-up?
[9 marks]
(d) What other considerations should be made prior to scale-up to the factory?

[6 marks]
[Total 25 marks]
END OF PAPER