Reaction Engineering 1 Design Project Spring Term 2022
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Reaction Engineering 1 Design Project
Spring Term 2022
Reactor Design Project: Hydrogen Cyanide Synthesis
Introduction
Your efforts to design a controller for a bioreactor met with great success and praise from your clients. Drunk off these compliments, you begged for a bigger challenge with more danger and excitement. Your boss has therefore put you in charge of the DEsign of A high-THroughput reactiON pAthway with SuperfasT Intrinsic Cyanide Kinetics (DEATHONASTICK) project, involving the production of hydrogen cyanide.
Hydrogen cyanide (HCN) is an important chemical used in a variety of applications in fumigation, electroplating and mining. It is most importantly used as an essential reagent in the production of synthetic polymer fibres (polyamides) as well as pesticides and dyes. Polyamides are used in textiles and carpet fibres in additional to packaging and other applications.
Unfortunately, conventional HCN production routes are dangerous, highly polluting and inefficient. Therefore, your company chemists have developed an environmentally synthetic route to cyanide from ammonia and methane using a catalyst that your chief chemist has been working on since 1955. Unfortunately, they are chemists and therefore have absolutely no idea how to carry out the reaction at scale.
Your task is to design a catalytic reactor to produce hydrogen cyanide from nitrogen gas. MATLAB will be used to carry out the calculations and simulations. The inlet conditions to be used are given in Table 2. Data for HCN synthesis (rate equations, heat capacities, equilibrium constant etc) are given below.
The Design Project
Your boss has told you to design an adiabatic catalytic reactor to produce 150 tonnes per day of HCN with a single catalyst bed, using the inlet conditions given in Table 2.
REACTION KINETICS
There are two reactions occurring in parallel. One is cyanide synthesis (desired) and the other is ammonia degradation (undesired):
2 3 ↔ 2 + 3 2 (2)
The rate expressions for the two reactions have been careful measured by a research group at a prestigious UK university:
∗ 4 ∗3
[ 1+∗]4 ∗
2 = 2∗ 3
(4)
Where:
= 1.6189 ∗ ()
2 = 0.0371 ∗ ()
2390
= 1.2050 ∗ (bar-0.5)
Using Matlab, generate data and create the following plots:
• Catalyst weight vs. extent of reaction 1
• Extent of reaction 2 vs. extent of reaction 1
• T vs. extent of reaction 1
• P vs. extent of reaction 1
In addition, make a plot of the rate of reaction 1 vs. the extent of reaction 1
Consider the operating conditions in the single adiabatic catalyst bed. Pay attention to the efficiency of use of the catalyst i.e. HCN production/weight of catalyst. Consider and discuss ways in which this can be improved. Use additional simulations as necessary.
You will need to investigate the possibility of increasing or decreasing the flow rate into the reactor (i.e. changing production capacity) in response to changes in market demand or random accounting decisions.
You will also need to include in this study an investigation of the sensitivity of the design to the various reaction parameters. This is necessary because the parameters were obtained from an academic research group at a disreputable university (Cambridge).
• Kinetics reaction parameters A-E
• Temperature dependence of the heat capacities
• Equivalent catalyst particle diameter
• Catalyst voidage
ASSUMPTIONS
a) The gas is perfect at all temperatures and pressures (despite the high pressure)
b) The gas is in plug flow in the reactor.
DATA
a) Heat Capacity
Cp (in units of J.mol-1 K-1) of each pure component is a function of temperature only, given by:
= a + bT + cT2 + dT−2
with constants:
|
a |
b x 103 |
c x 106 |
d x 105 |
NH3 |
3.578 |
3.020 |
- |
-0.186 |
CH4 |
1.702 |
9.081 |
-2.164 |
- |
H2 |
3.249 |
0.422 |
- |
0.083 |
HCN |
4.736 |
1.359 |
- |
-0.725 |
N2 |
3.280 |
0.593 |
- |
-0.040 |
Assume the heat capacity of the mixture is a mole fraction weighted sum of the individual
heat capacities. For a mixture with mole fractions yi :
C = ∑ C
e) Catalyst data
The catalyst particles are cylinders of diameter 5.5 mm and length 16 mm (equivalent particle diameter of 7.04 mm) and have a (particle) density of 1400 kg/m3 . The bed voidage may be taken as 0.4
f) Pressure drop
It can be assumed that the pressure gradient in a fixed-bed of particles governed by the Ergun equation which, for these Reynolds numbers, reduces to:
= −
where G is the superficial mass velocity of the fluid (mass/(time*area)).
ε is the bed voidage
Dp is the equivalent particle diameter
ρ is the gas density
Project Logistics
1. Duration and assistance. The project is available now (otherwise you could not read this). The project will run for two term weeks (28 February until 11 March). There will be GTA assistance available both in person and via MS Teams on Mondays, Tuesdays, Thursdays and Fridays from 0900- 1200. Please wait in the main MS Teams channel for a GTA to take you to a breakout room (for group privacy/commotion reduction). Your course coordinator will be available via Blackboard, or you can make an appointment via email to discuss any group issues.
2. Groups. Your boss has assigned you to a group of (normally) 4 engineers for the duration of the project. Because of your boss’s abhorrence of paperwork, there will be no switching permitted.
3. Assessments. The project will be assessed in the following ways:
a. MATLAB programme for reactor design (1 per group!) – 40%
b. Reactor design report (1 per group!) – 60%
4. Notes
a. You MUST use MATLAB version R2021b for your design and simulations
5. Deliverables
a. Submit your best Matlab code by 1 1/03/22 at 1630
b. Submit your report by 1 1/03/22 at 1630
Marking scheme for the reactor report:
• Presentation: overall style, clarity and organisation 20%
• Description of theory 20%
• Results and discussion of the initial simulations 25%
• Results and discussion of the advanced/sensitivity analyses 35%
Report Guidelines
The following items are to be submitted:
(a) One report
The submission of one report by each group of students will be required. Please use the normal departmental template for report writing. A penalty will be imposed on reports exceeding the page limit. Arial 11-point font (minimum) and 2 cm margins (minimum) . Single spacing is acceptable.
Each report should not exceed 10 pages, including main body text and all figures (introduction through conclusions, inclusive), but excluding the title page, author names, abstract, references or table of contents.
Do not try to include all of the results you generate but do include meaningful analyses to go with the figures or tables. Adopt compact and efficient ways to present the results. A compare- and-contrast approach may be helpful with overlaid plots from different simulations shown on the same graph with appropriate legends (you can programme Matlab to do this for you or manually transfer the data).
The following is a suggested structure for the report and the topics for inclusion under the major headings. There is also a suggestion of an appropriate page limit for the different headings.
Section |
pages |
Abstract |
- |
Introduction |
1 |
Theory and Methodology |
3 |
Results and discussion of basic design |
2 |
Results and discussion of sensitivity analysis |
3 |
Conclusions |
1 |
Overall page limit – 10. No addendum permitted.
(i) Abstract and Keywords: The abstract must summarize the content of the report and the main conclusions. This is normally a short paragraph.
(ii) Introduction: The HCN process description; general aims and objectives of the reactor design and specific aims for this HCN process.
(iii) Theory and Methodology: Only the theory and methods used in the work should be presented (the report is not a tutorial). It can cover the chosen reactor design elements and any required details on mass balances, reactor modifications, etc., with salient equations as appropriate; methodology to implement these strategies or any experimental simulations.
(iv) Results and analysis: Results and analysis (not all cases, but the ones that you judge as the most important); sample calculations; clear statements of parameters used and simulations performed. The use of multiple plots on one set of axes is useful for showing comparisons.
(v) Discussion: The discussions must give insights. It is not enough to just describe the results. One way is to make tables or graphs showing trends and to provide an explanation for the observed trends. (vi) Conclusions and suggestions for future work to improve your design.
Report Marking
Reports are due to be submitted electronically (BlackBoard) by 16:30 on Friday 11th March. Late submissions will be penalized. It is wise to allow plenty of time when attempting submission at peak times in case the electronic submission system becomes overloaded.
Marks will be awarded for quality of the results and presentation of the report. The assessors will look for: Good English and proper grammar including appropriate punctuation marks; organisation of the report in a coherent and logical manner with sections and sub-sections as necessary under the major headings; inclusion of proper citations and references; good formatting including figures with legible lines, appropriate background, legend positioned appropriately and figures of proper size (neither too big nor too small); titles for figures and tables placed appropriately (below the figures and above the tables) and labelled accordingly. Proofread carefully to identify typos (I did!)
Reports are checked against each other as well as those from previous years, and against other electronic sources worldwide using the TurnItIn service.
Reports showing evidence of plagiarism are always penalized.
(b) Program listing
ONE copy of the Matlab program files should be sent in a single .zip file by e-mail to (ic.rdcp@gmail.com - please do not cc the module leader) indicating all group member names. The computer program should be well documented, and in particular, units of calculated quantities should be added in comments. Due by 1630 on Friday, 1 1th March.
File type and naming
• Reactor design
• Please use one reactor design programme if possible (i.e. ‘HCN_reactor_design’)
• Otherwise – please ensure all files are appropriately named and collected in a single zip file:
▪ Compress this folder to a .zip and rename it to ‘RD Group [Group number].zip’ . So for example group 54 would submit ‘RD Group 54.zip’
• Submission
• Submit one .zip file toic.rdcp@gmail.comwith the subject line ‘Group [Group Number] - files’ . Send ONE email per group. Please do not cc the module leader.
(c) Data files
All additional calculations that were carried out in spreadsheets, etc. should be included in a data file and e-mailed along with the program files in the .zip folder.
(d) Individual reactor design derivations
At the beginning of the course, all students will be expected to individually derive the PFR design equation for the reactors. Please note that you are not expected to analytically solve this design equation, as it is likely impossible.
It is also suggested to check your initial reactor design with the GTAs with an initial rate check (i.e. the rate at the reactor inlet) using the initial conditions only. This is possible before programming any loops into the programme and can be verified by hand calculation .
Other information
• Please post any questions on the Discussion Board on Blackboard. Please do not e-mail questions to the module leader – he is likely to just tell you to post it on Blackboard because he is rude.
• Please do not send your project files (code, report) to the module leader or cc him, as this will cause his inbox to crash and make him sad.
• Table 2 (each group’s inlet conditions for the reactor design) is on the next page
2022-06-17
Reactor Design Project: Hydrogen Cyanide Synthesis