Hello everybody.
I’m trying to simulate a conventional distillation column by using ChemSep CAPE-OPEN Unit Operation. Everything it’s ok until I run the model. In the ChemSep environment the run button it does not appear and when I run the model form DWSIM environment, product flows (Distillate and Bottoms) are zero.
I’m sure is something that I miss to do.
Other thing, I’m trying to simulate a 3-phase separator for the mixture water-methanol-toluene-ethylbenzene-styrene. Aspen Plus predicts LLV equilibrium but not DWSIM. I did different simulations taking into account the Flash Algorithm on Advanced Thermo. I used the PRSV2-M property package in both simulators (Aspen and DWSIM)
Thank you for your time
Juan
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Hello everybody.
I’m trying to simulate a conventional distillation column by using ChemSep
CAPE-OPEN Unit Operation. Everything it’s ok until I run the model. In the
ChemSep environment the run button it does not appear and when I run the
model form DWSIM environment, product flows (Distillate and Bottoms) are
zero.
I’m sure is something that I miss to do.
Other thing, I’m trying to simulate a 3-phase separator for the mixture
water-methanol-toluene-ethylbenzene-styrene. Aspen Plus predicts LLV
equilibrium but not DWSIM. I did different simulations taking into account
the Flash Algorithm on Advanced Thermo. I used the PRSV2-M property package
in both simulators (Aspen and DWSIM)
Regarding the Column example, that suppose to happen. when you use a
ChemSepUO you must run the simulation via DWSIM not ChemSep itself. I think
the problem here is related to a CAPEOPEN interface bug. Daniel could you
check this error?.
Now for the LLVE, are you calling DWSIM PRSV Property Package From Aspen?,
which components does Aspen calculates on the aqueous and organic stream?
Have you tried with UNIFAC-LL?
Last edit: Gustavo León 2016-05-16
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Hi Gustavo,
I used the PRSV from Aspen Plus not from DWSIM.
Organic phase: Toluene, benzene, ethylbencene and the most of methanol
Aqueous phase: Water and some methanol.
It shoud work with an EOS equation as PR, but i will try with UNIFAC-LL, thank you
By the way, I'm also trying to converg the attached PFR with kinetic reactions.
I just read the post "Kinetics in PFR don`t work" but I could not fix my simulation.
For the column issue, uncheck the "CAPE-OPEN Properties" item on the CAPE-OPEN tab. DWSIM's thermodynamics exposes a solid phase and chemsep doesn't handle it yet. You'll have to use one of ChemSep's own models. I don't know if they support two liquid phases.
For the LLE issue, make sure to use a VLLE flash algorithm and a model capable of predicting it. DWSIM only has a small subset of interaction parameters for PRSV, so it is always better to use a UNIFAC-type model in this case.
For the PFR issue, check the reactor volume and kinetic reaction parameters, specially the reverse reaction ones.
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Hi Juan,
i did a check of the utilised property package.
You may use either NRTL, UNIQUAC, or Modified Unifac. UNIFAC-LL is not recommendet as not all required interaction parameters are available. This model is outdated and only suitable for pure liquid/liquid equilibria. UNIFAC has no temperature dependent coefficients. Therefore Modified Unifac is the best model for this case. I reccomend the NIST version as this model is newer and presumably has better parameters than the Dortmund version.
Both NRTL and UNIQUAC don't have all necessary interaction parameters in the database. You may supply them by a calculation with one of the Modfac models in PP configuration dialog.
I had to remove hydrogen from your component list as this component does create some kind of problem in liquid phase stability check (we will have to investigate further on that issue). I also changed the flash procedure to Nested Loop VLLE which usually gives the most stable results.
For your reference, the modified sample was attached.
Thank you very much.
I solved the problems with the LLV. The main problem was the hydrogen. I used a component separator to remove the hydrogen entering the Separator Vessel. The simulation works with PR also but the equilibrium is best reproduced with UNIQUAC (NIST).
Regarding the problems with the PFR. With the new version of DWSIM is solved. However I could not solve the problems with the distillation column using ChemSepUO.
Thank you for your time.
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Even if your immediate problem is solved, this is still regarded as a workaround only. I will have a deeper look into this issue why hydrogen is causing this problem. Hydrogen is a supercritical component. VLLE calculations with these kind of components can be very tricky to be calculated in some cases.
Gregor
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
Hello everybody.
I’m trying to simulate a conventional distillation column by using ChemSep CAPE-OPEN Unit Operation. Everything it’s ok until I run the model. In the ChemSep environment the run button it does not appear and when I run the model form DWSIM environment, product flows (Distillate and Bottoms) are zero.
I’m sure is something that I miss to do.
Other thing, I’m trying to simulate a 3-phase separator for the mixture water-methanol-toluene-ethylbenzene-styrene. Aspen Plus predicts LLV equilibrium but not DWSIM. I did different simulations taking into account the Flash Algorithm on Advanced Thermo. I used the PRSV2-M property package in both simulators (Aspen and DWSIM)
Thank you for your time
Juan
Hi Juan,
Could you attach the simulation file to check?. What version of DWSIM are
you using?
Gustavo.
On Mon, May 16, 2016 at 8:29 AM, Juan javaloyes@users.sf.net wrote:
Hi Juan,
Regarding the Column example, that suppose to happen. when you use a
ChemSepUO you must run the simulation via DWSIM not ChemSep itself. I think
the problem here is related to a CAPEOPEN interface bug. Daniel could you
check this error?.
Now for the LLVE, are you calling DWSIM PRSV Property Package From Aspen?,
which components does Aspen calculates on the aqueous and organic stream?
Have you tried with UNIFAC-LL?
Last edit: Gustavo León 2016-05-16
Hi Gustavo,
I used the PRSV from Aspen Plus not from DWSIM.
Organic phase: Toluene, benzene, ethylbencene and the most of methanol
Aqueous phase: Water and some methanol.
It shoud work with an EOS equation as PR, but i will try with UNIFAC-LL, thank you
By the way, I'm also trying to converg the attached PFR with kinetic reactions.
I just read the post "Kinetics in PFR don`t work" but I could not fix my simulation.
Thank you very much for your time.
Hi Daniel,
thank you for yor interest.
I'm using DWSIM 3.7
For the column issue, uncheck the "CAPE-OPEN Properties" item on the CAPE-OPEN tab. DWSIM's thermodynamics exposes a solid phase and chemsep doesn't handle it yet. You'll have to use one of ChemSep's own models. I don't know if they support two liquid phases.
For the LLE issue, make sure to use a VLLE flash algorithm and a model capable of predicting it. DWSIM only has a small subset of interaction parameters for PRSV, so it is always better to use a UNIFAC-type model in this case.
For the PFR issue, check the reactor volume and kinetic reaction parameters, specially the reverse reaction ones.
Hi Juan,
i did a check of the utilised property package.
You may use either NRTL, UNIQUAC, or Modified Unifac. UNIFAC-LL is not recommendet as not all required interaction parameters are available. This model is outdated and only suitable for pure liquid/liquid equilibria. UNIFAC has no temperature dependent coefficients. Therefore Modified Unifac is the best model for this case. I reccomend the NIST version as this model is newer and presumably has better parameters than the Dortmund version.
Both NRTL and UNIQUAC don't have all necessary interaction parameters in the database. You may supply them by a calculation with one of the Modfac models in PP configuration dialog.
I had to remove hydrogen from your component list as this component does create some kind of problem in liquid phase stability check (we will have to investigate further on that issue). I also changed the flash procedure to Nested Loop VLLE which usually gives the most stable results.
For your reference, the modified sample was attached.
Gregor
Last edit: Gregor Reichert 2016-05-17
Thank you very much.
I solved the problems with the LLV. The main problem was the hydrogen. I used a component separator to remove the hydrogen entering the Separator Vessel. The simulation works with PR also but the equilibrium is best reproduced with UNIQUAC (NIST).
Regarding the problems with the PFR. With the new version of DWSIM is solved. However I could not solve the problems with the distillation column using ChemSepUO.
Thank you for your time.
Even if your immediate problem is solved, this is still regarded as a workaround only. I will have a deeper look into this issue why hydrogen is causing this problem. Hydrogen is a supercritical component. VLLE calculations with these kind of components can be very tricky to be calculated in some cases.
Gregor
Juan, did you manage to use one of ChemSep's internal models?