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Modeling Pyrolysis Oil In Aspen Batch Model


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#1 waheed2020

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Posted 11 December 2020 - 06:18 PM

Dear Group Members,

 

I have pyrolysis oil for which I need to model it in ASPEN batch model. I have SG, boiling curve and composition. Can anyone guide me on how can I do the simulation? The components are more than 300 and some are pure the rest are hypos for which I don't know the structure and even I cant ignore them . Any expert that can help me.

 

I would be thankful



#2 Pilesar

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Posted 12 December 2020 - 01:36 AM

Enter your stream as an assay using your boiling curve and density. This will allow the program to assign a shorter list of new pseudocomponents different from the detailed component list you have and more suitable for computer simulation. The composition you have will only be useful to characterize any light ends if they exist. Search for 'assay' in the simulation program help files. I recommend you contact the AspenTech support desk since you will probably need more personal guidance if you have never previously entered an assay stream.



#3 waheed2020

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Posted 12 December 2020 - 01:14 PM

Hi,

 

Thanks for your reply. I have experience with entering the assay in aspen hysys and generation of hypos. The problem is that behavior of pyrolysis oil is different from crude oil. For example only C9 component is 18% of the whole pyrolysis oil so if I use crude approach aspen will treat the oil as crude assay but not pyrolysis oil.

 

To accurately model the oil, I really need to enter composition as well. I contacted aspentech a while ago. They replied after 2 months and they assigned a training but we never get a response after that which was strange.



#4 waheed2020

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Posted 12 December 2020 - 01:18 PM

May be one more question. I am very confuse with the boiling curves. Which is the most suitable or accurately represent boiling curve. TGA curve, ASTM D86, ASTM2887, TBP? 

 

Thanks 



#5 Pilesar

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Posted 12 December 2020 - 08:26 PM   Best Answer

Pyrolysis oil is not a single stable composition. It changes depending on when you measure it. The written composition you have reflects one sample. So you don't have to be exactly exact when you model the stream in simulation. You want something that is representative for the answers you are seeking. You should determine what questions you are trying to answer before beginning the model. Then tailor your model so that it will be adequate. 
 
The chemical composition would be useful if you were reacting some specific components further. Even then, you would lump many of the 300 components identified into much smaller groups according to the similarities you need. 
 
Boiling point curves are found by taking a sample and following prescribed procedures. Lab measurements to characterize boiling point differ. Some are performed at atmospheric pressure in the presence of air, some under vacuum, some are simulated by chromatograph. The same sample will give different measurements depending on the lab method used. The true boiling point lab method is costly to perform so the other methods were developed which give quicker and cheaper results. The differences between methods are such that conversion factors can be applied to approximate True Boiling Point. It may be reasonable to assume the boiling point curve you have is supposed to represent True Boiling Point, but look over the data closely as it should give some clue. Remember that a single assay sample taken a year ago will not match a sample taken today. So process design must allow for variability.


#6 ChEf

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Posted 13 December 2020 - 07:54 PM

I would apply the same approach used to characterize a naphtha. The pyoil distillation curve, its density, its PIONA are the input data. Select a desired number of compounds (aromatics, paraffinic, isoparaffinics, etc) within the IBP and the EBP of the distillation curve. Then try to adjust the composition of the selected compounds to match the distillation curve, the density and the PIONA of the pyoil. Selected a number of compounds that is aligned with your needs.

#7 waheed2020

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Posted 14 December 2020 - 12:40 PM

Dear Pilesar & Francesco,

 

Thank you both of you for your helpful answers. I am very new to research on oil.

My objectives are to produce sharper cuts with distillation column may be naphtha cut, heavier than and residue and model then same in aspen for economic evaluation (for me its a bit difficult but I will try)

 

 An addition, TGA curve (loss of weight (%) vs temperature graph) which requires only 20mg of sample and takes only 30 minutes to perform produce more or less similar curve to ASTM D86 distillation Curve. My question is that it is fine to model the oil using TGA curve or  you suggest it is wise to buy D86 setup? 

 

I have another setup of distillation column which is calibrated by ASTM D2892 method. The column has 8 theoretical plates, 1 m height with vacuum pump and refluxing valve that is also be able to produce distillation curve?



#8 Pilesar

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Posted 14 December 2020 - 03:38 PM

You are leaving out much information that would help us understand what you are doing. Sometimes questions are asked in these forums that go unanswered because the problem is not stated adequately. You seem to be trying to supply information and probably think you have told us enough to get answers. If you don't get the responses you are seeking, consider that there may be some breakdown in communicating your thoughts to written words for others to understand your thoughts. I cannot guarantee that there is anyone on this forum who is able to help you. But even if they were capable and willing to help, they might not invest themselves to try to coax the needed information from you. 


#9 waheed2020

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Posted 14 December 2020 - 06:46 PM

Dear Pilesar,

 

Sorry for being bad with the communication. I would repeat my question in simple way. If I use Thermo Gravimetric Analysis(TGA) measurements to characterize boiling point difference of Pyrolysis oil?  Is there any method for conversion of TGA curve to approximate True Boiling Point.

 

Thank you for time.






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