Hello
We are senior students in college, studying mechanical engineering and our graduation project is:
“Designing pyrolysis unit for waste car tires”
And we had a difficulty in collecting data. For the past six months we have been reading and searching many scientific papers about the chemical reaction that happens inside of the reactor, to get a grasp on the whole concept of pyrolysis [and the mass + energy balance] that we need to know the limit of design for our unit.
Clearly we are mechanical engineering students so our chemical knowledge is pretty limited so we need your help to get a [chemical equation] that describes the reaction happening inside of the reactor so we can get the right data for the design.
Unfortunately we live in Sudan .the resources are limited , but the data about this subject doesn't cover how can we form the chemical equation and to simulate the reaction.
So we need your help. :)
Dear Mohamed,
One of the proper solutions of your problem to get the reaction equation for the pyrolysis of the tires is to consult a chemical expert in the faculty of science at Khartoum university itself. So, you can mange to make your project as a joint venture project. It is not easy to get the exact reaction equation except with equilibrium reactions and with dynamic reactions.
May be a pragmatic way is to make a pilot experiment and measure the dissociation rate of the tires and the energy spent in the reactions and the reaction products using chemical analysis methods.
This may be what exactly you ask for but they are some proposal to solve this problem.
Best wishes
1. Determine what the reactant in waste-car tires is, e.g. rubber and so on.
2. Read on some papers and determine chemical reaction involved in its pyrolysis
3. Work on the mass and energy balance
The most important part is how you develop the pyrolysis unit, the reaction might come second. Just determine on the main reactions involved and work from there.
Good luck.
I recommended for you the answer of Prof.Dr. Abdelhalim Zekry, the proper equation should be obtained from experimental results.
I also agree with the answer of Prof.Dr. Abdelhalim Zekry,
Regards
1. The first step is to design a pyrolysis system, it can be a fixed bed system or an entrained-flow pyrolysis system. But I think a fixed bed/batch system will be the simplest one.
2. Determine your pyrolysis conditions, the most important one is the pyrolysis temperature. keep in mind they are three forms of pyrolysis ( slow, intermediate, and flash/fast).
3. When that is done, now you can get into sample preparation and characterization. Get your samples (in this case waste tires) shredded, and sieve them to certain specific particle sizes. After that, you need to do the proximate analysis (volatile matter, ash, moisture, fixed carbon), and ultimate analysis ( CHNS/O).
4. Pyrolysis will result in three products which are bio-oil, bio-gas, and bio-char. Depending on the pyrolysis conditions different compositions of bio-oil, bio-gas, and bio-char are formed.
5. Looking at your products you can then come up with reaction mechanisms on how you think they were formed, and that will get you your reaction equations.
6. For example, if you notice that as you change your temperature you have a sudden increase in H2 gas and CO2, at the same time CO is reducing then water gas shift reactions are taking place. H2O + CO = CO2 + H2
7. Also, higher pyrolysis temperatures might favor secondary reactions. (you can research more on this)
I hope this helps.
Regards
Unfortunately@Abdelhalim Zekry due to the Corona epidemic, it is difficult to communicate with other departments of the university, knowing also that we are in the second semester and in general the situation does not allow movement and experimentation, and therefore we need a solution commensurate with the situation easy to implement.
Do you have any other advice that might match the situation?
best wishes
Mohamed Koko I can see you might have already submitted your project. However I will put my answer for the sake of those who might face the same problem in future. For the purposes of an Honours project in an Engineering department, I don't think you need to go deep into the chemistry involved. I will advise to use a simple pyrolysis decomposition equation as follows
Tyre >>> Char + Volatiles
You can google research papers that have presented tyre pyrolysis work (multitudes of them), most of them present the CHNS and proximate analysis of their tyres (keep in mind tyres might have different formulations). However, you can collect papers that have presented results on tyres that have almost similar properties. Check the yields of the char and volatiles that have been reported in all the research papers you have collected. By doing so, you can get an approximate mass balance (or chemical equation of the process). You can then use that equation in your design calculations, after-all it will be supported by the research papers that you used. I suggest this because I know very well how difficult it is to perform research that involves experiments in a third world country university because of lack of instruments (for example a TGA, GC-MS, Elemental analyser or XRF etc).
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