Crude distillation

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Crude distillation

Postby arvind.prasad » 17 May 2016, 12:20

Can we simulate and ADU (Atmospheric distillation Unit) for crude in COCO??
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Re: Crude distillation

Postby jasper » 17 May 2016, 12:31

Yes. The distillation column is no different in setup than any other distillation column, but you will probably want to define a number of pseudo compounds that characterize the crude. The PCD Manager that comes with ChemSep will help you set up a pseudo compound slate that you can use in your simulation.
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Re: Crude distillation

Postby arvind.prasad » 17 May 2016, 13:41

Here is How I went about it. Open Cape Open simulator. Once the flowsheet environment is open, click settings>Property Packs>add> Chemsep Property pack manager and select it. Give it a new name ( gave it crude distillation). It opens Chemsep environment in this. In the chemsep environment, click on pseudo's. After that things are not clear. Is there any example that I can follow?
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Re: Crude distillation

Postby hkooijman » 17 May 2016, 14:06

Unfortunately there isn't a manual yet. The pseudo panel needs some kind of a measured ASTM curve, to generate a set of pseudo components in a PCD library. This library with pseudo components then need to be read back into COCO again. Currently, this is not (yet) automated in any sense as it was meant as a stand alone generation of pseudo's for ChemSep, not as something that works in a nice way with COCO. The advantage is that some of the refinery properties are defined. There is a generic tutorial on pseudo components by hand on http://chemsep.org/downloads/docs/ChemS ... ticals.pdf but this follows a completely manual way of setting pseudo compounds. Unfortunately, though it is planned to be tackled there is no time to quickly fix this ...

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Re: Crude distillation

Postby jasper » 17 May 2016, 15:14

There is possibly the path of generating a (partial) PCD file in xml form, using any off line recharacterization tool. If you have one available.
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Re: Crude distillation

Postby arvind.prasad » 17 May 2016, 17:52

Thanks Mr. Harry. I have simulated the tutorial. It was of great help. I will take up a crude distillation problem and try to solve it. Incase I get stuck will get back to you.
hkooijman wrote:Unfortunately there isn't a manual yet. The pseudo panel needs some kind of a measured ASTM curve, to generate a set of pseudo components in a PCD library. This library with pseudo components then need to be read back into COCO again. Currently, this is not (yet) automated in any sense as it was meant as a stand alone generation of pseudo's for ChemSep, not as something that works in a nice way with COCO. The advantage is that some of the refinery properties are defined. There is a generic tutorial on pseudo components by hand on http://chemsep.org/downloads/docs/ChemS ... ticals.pdf but this follows a completely manual way of setting pseudo compounds. Unfortunately, though it is planned to be tackled there is no time to quickly fix this ...

Harry
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Re: Crude distillation

Postby arvind.prasad » 18 May 2016, 05:18

The starting point of solving any crude distillation problem is to enter the TBP vs volume data and create psuedo components, based on MBT ( Mid Boiling Temperature). I am not able to figure out how do I do this? I have to TBP volume data, Where do I enter it?
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Re: Crude distillation

Postby jasper » 18 May 2016, 07:25

TPB data go into a recharacterization scheme, that determines for each of the pseudo compounds with a boiling range how to best adjust the pseudo characterization properties (e.g. in an equation of state, the pseudo critical temperature, pseudo critical pressure and pseudo acentric factor) and composition to fit, typically, the boiling curve and density or volume yield curve, subject to constraints of e.g. continuity, zero slope at the end of the curve, etc. It is my understanding that it is exactly the recharacterization scheme that is not (yet) in place in ChemSep.

Given the density and the boiling point of a given pseudo, the PCD manager can estimate the pseudo critical properties using correlations; it can be done for a range directly in ChemSep itself. However, creating the density and boiling point (and yield) of each pseudo from the TBP curve is the missing step at this point.

Harry - correct me if I am wrong please.
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Re: Crude distillation

Postby arvind.prasad » 18 May 2016, 14:54

In chemsep there is another psuedo component creator( a psuedo's button). If you click on component, it is on the pane to the right of component list, below "Add new" and above, "Show". I would like to know, if it works. I have tried using it. If you click on pseudo's button, a window opens that has an TBP vs volume, specific gravity, table on the top left.This is already filled with some values. On clicking the "cut" button, it recharacterizes the crude, giving the MBT(Mid Boiling temperature) of the cut, volume of the cut and the specific gravity of the cut. Further if you click on "compute" button, it calculates the Molecular Weight, Weight Percent and mole percent of the cuts. I would like to know if this feature is working or on the developmental stage. And yes can I independently put the TBP and SG and recalculate for my problem. If yes I will try using it to do some simulations.
jasper wrote:TPB data go into a recharacterization scheme, that determines for each of the pseudo compounds with a boiling range how to best adjust the pseudo characterization properties (e.g. in an equation of state, the pseudo critical temperature, pseudo critical pressure and pseudo acentric factor) and composition to fit, typically, the boiling curve and density or volume yield curve, subject to constraints of e.g. continuity, zero slope at the end of the curve, etc. It is my understanding that it is exactly the recharacterization scheme that is not (yet) in place in ChemSep.

Given the density and the boiling point of a given pseudo, the PCD manager can estimate the pseudo critical properties using correlations; it can be done for a range directly in ChemSep itself. However, creating the density and boiling point (and yield) of each pseudo from the TBP curve is the missing step at this point.

Harry - correct me if I am wrong please.
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Re: Crude distillation

Postby hkooijman » 18 May 2016, 16:44

Please note that these panels are still in a development phase. There was no rationalization yet how to integrate all in a nice manner with COCO for example. We allowed access to these panels for experts that know what they are doing.

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