Re: [dwsim-users] reactor application - ethyl acetate

[Daniel W. <dan...@gm...>]

Can you send me your file again?

2016-04-27 9:52 GMT-04:00 Hector Perez <hpe...@gm...>:

> Daniel, there may be a bug then because my absolute pressure leaving the
> PFR is ~0.8 atm. If I increase the reactor length by 1 cm more, then I get
> the pressure drop error.
>
> Nice, yes we are close. Ainda nao tem ido ao Brasil mas tenho escutado que
> e muito bonito la.
>
> Hector D. Perez
> Chemical Engineering Consultant
>
> On Wed, Apr 27, 2016 at 8:42 AM, Daniel Wagner <dan...@gm...>
> wrote:
>
>> Hector, the actual criteria for throwing the pressure drop error in the
>> PFR model is a negative pressure value after the pressure drop calculation
>> step:
>> https://github.com/DanWBR/dwsim3/blob/master/DWSIM/Objects/Reactors/PFR.vb#L828
>>
>> Hey, we live relatively close to each other. I'm in Manaus, Amazonas.
>> Could we say that both of us live in the Amazon? :-)
>>
>> Regards,
>> Daniel
>>
>>
>> 2016-04-27 9:30 GMT-04:00 Hector Perez <hpe...@gm...>:
>>
>>> I see. Thank you Daniel for taking the time to answer my questions. I
>>> look forward to continuing to use DWSIM and spread the word here in
>>> Colombia. You've done an amazing job with this program.
>>>
>>> Have a nice day,
>>>
>>> Hector D. Perez
>>> Chemical Engineering Consultant
>>>
>>> On Wed, Apr 27, 2016 at 8:28 AM, Daniel Wagner <dan...@gm...>
>>> wrote:
>>>
>>>> Hi Hector,
>>>>
>>>> For liquids, a high pressure drop would be one that vaporizes part of
>>>> it... for gases, I guess that it would be worse because gas properties are
>>>> heavily dependent on pressure, and that can cause changes in concentrations
>>>> and/or fugacities, impacting the final conversion.
>>>>
>>>> Regards
>>>> Daniel
>>>>
>>>>
>>>> 2016-04-27 9:22 GMT-04:00 Hector Perez <hpe...@gm...>:
>>>>
>>>>> Hi Daniel,
>>>>>
>>>>> Thank you for the clarification. What is the criteria for "high
>>>>> pressure drop" in a PFR? I'm seeing that in the acetate problem, DWSIM
>>>>> won't let me go beyond a pressure drop of 0.23 atm.
>>>>>
>>>>> Thanks,
>>>>>
>>>>> Hector D. Perez
>>>>>
>>>>>
>>>>> On Wed, Apr 27, 2016 at 8:09 AM, Daniel Wagner <dan...@gm...>
>>>>> wrote:
>>>>>
>>>>>> Hi Hector,
>>>>>>
>>>>>> I don't know how the volume calculation works on Aspen but, in DWSIM,
>>>>>> I do the following:
>>>>>>
>>>>>> PFR code (use this for line number references in the text below):
>>>>>> https://github.com/DanWBR/dwsim3/blob/master/DWSIM/Objects/Reactors/PFR.vb
>>>>>>
>>>>>> - For the PFR, if you have a reactor of volume X, and the volume
>>>>>> delta is 0.05, then the ODE (ordinal differential equation system) mass
>>>>>> balance calculation will be done in 0.05*X volume steps until the entire
>>>>>> volume is calculated (line 832). If you don't care about the actual
>>>>>> pressure drop calculation, you can enter any value for the reactor length.
>>>>>> Just be sure to input a length that doesn't result in a high pressure drop
>>>>>> across the reactor. DWSIM calculates the pressure drop using the reactor
>>>>>> volume and length to estimate the internal diameter, then uses the Darcy
>>>>>> formula to calculate pressure drop. If the reactor has a catalyst bed, then
>>>>>> the Ergun formula is used (line 797).
>>>>>>
>>>>>> CSTR code (use this for line number references in the text below):
>>>>>> https://github.com/DanWBR/dwsim3/blob/master/DWSIM/Objects/Reactors/CSTR.vb
>>>>>>
>>>>>> - For the CSTR, the entire reactor volume is used at once and the ODE
>>>>>> system is solved one time only (lines 559/111). There is no pressure drop
>>>>>> calculation because this is supposed to be a batch (tank) reactor. :-)
>>>>>>
>>>>>> Regards
>>>>>> Daniel
>>>>>>
>>>>>>
>>>>>>
>>>>>> 2016-04-27 0:06 GMT-04:00 Hector Perez <hpe...@gm...>:
>>>>>>
>>>>>>> Hi Daniel,
>>>>>>>
>>>>>>> Thanks for sending the file along with the updated build! I actually
>>>>>>> went through the file and included the reverse reaction by adjusting the
>>>>>>> Reverse Order exponents (the Aspen Plus video has both forward and reverse
>>>>>>> reactions). I also dropped the conversion on the Conversion reactor
>>>>>>> (to~70%) and set the equilibrium constant (for the Equilibrium Reactor) to
>>>>>>> be k_forward/k_reverse (ratio of rate constants). My numbers are now very
>>>>>>> close, if not the same as the ASPEN simulation video.
>>>>>>>
>>>>>>> One thing I did run into is that the reactor dimensions for the PFR
>>>>>>> and CSTR in the aspen video create errors in DWSIM. I had to decrease the
>>>>>>> PFR length because it gave me a warning about the pressure drop being too
>>>>>>> high. The CSTR volume also had to be decreased because it gave me a mass
>>>>>>> balance error. Do you know why the aspen dimensions don't work? This could
>>>>>>> perhaps be a lack of feasibility check on the ASPEN side.
>>>>>>>
>>>>>>> Also, what is "Volume Delta (Relative)" on the PFR specs?
>>>>>>>
>>>>>>> One other thing I checked was the CSTR duty (compared to the ASPEN
>>>>>>> video) and found the DWSIM value to be about 6 times lower than the ASPEN
>>>>>>> value (perhaps something having to do with the smaller volume used in
>>>>>>> DWSIM?).
>>>>>>>
>>>>>>> Thanks once again. I am really liking this simulator. It seems
>>>>>>> easier to use than aspen.
>>>>>>>
>>>>>>> Hector D. Perez
>>>>>>>
>>>>>>>
>>>>>>> On Tue, Apr 26, 2016 at 7:11 PM, Daniel Wagner <dan...@gm...>
>>>>>>> wrote:
>>>>>>>
>>>>>>>> Hi Hector,
>>>>>>>>
>>>>>>>> By following the Aspen Plus video I was able to make it work, there
>>>>>>>> is no reverse reaction. Also, there was a bug in the PFR pressure drop
>>>>>>>> calculation, you'll have to use an updated build. Download it from this
>>>>>>>> link and unpack the files in DWSIM's installation directory:
>>>>>>>> https://sourceforge.net/projects/dwsim/files/DWSIM/DWSIM%203.7/Build5960.rar/download
>>>>>>>>
>>>>>>>> Also, I forgot to tell you that, for kinetic reactions, every
>>>>>>>> compound in the reaction must be present even if in a small amount, i.e.
>>>>>>>> 0.000001. 0 will give you an error.
>>>>>>>>
>>>>>>>> You can also try the updated simulation file, I've added the
>>>>>>>> equilibrium reactor as well.
>>>>>>>>
>>>>>>>> Regards
>>>>>>>> Daniel
>>>>>>>>
>>>>>>>>
>>>>>>>> 2016-04-26 18:17 GMT-04:00 Hector Perez <hpe...@gm...>:
>>>>>>>>
>>>>>>>>> Hi Daniel,
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> For kinetic reactions, what are the units on the activation
>>>>>>>>> energy? (same units as those specified for the molar entropy?). I included
>>>>>>>>> the DO and RO exponents as well as the base compound and now get a new
>>>>>>>>> error on the CSTR: “An error occurred during the mass balance calculation.
>>>>>>>>> Check reaction kinetics data and reactor sizing information as well.”
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> The PFR gives me the error: “One or more flash specification
>>>>>>>>> values are invalid. Please check the associated UO or Material Stream for
>>>>>>>>> incorrect specifications or miscalculated values.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Thank you, I really appreciate your assistance.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Hector D. Perez
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> *From: *Daniel Wagner <dan...@gm...>
>>>>>>>>> *Sent: *Tuesday, April 26, 2016 3:59 PM
>>>>>>>>> *To: *Hector Perez <hpe...@gm...>
>>>>>>>>> *Cc: *dws...@li...
>>>>>>>>> *Subject: *Re: [dwsim-users] reactor application - ethyl acetate
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> For the existing reactions, you've missed the compound
>>>>>>>>> concentrations' direct and reverse order exponents. You also didn't define
>>>>>>>>> the base compound, which should be the main reactant.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> For the conversion and equilibrium reactors, you must define the
>>>>>>>>> corresponding reactions. Kinetic reactions only work with the PFR and the
>>>>>>>>> CSTR.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> 2016-04-26 16:43 GMT-04:00 Hector Perez <hpe...@gm...>:
>>>>>>>>>
>>>>>>>>> Hi,
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> I am trying to replicate the following ASPEN tutorial to set up
>>>>>>>>> the liquid reaction for ethyl acetate formation from ethanol and acetic
>>>>>>>>> acid using different types of reactors:
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> https://www.youtube.com/watch?v=_DOdlUDI-kI
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Unfortunately, only the Gibbs reactor yielded any result with a
>>>>>>>>> ethyl acetate flow that was 12 kmol/hr lower than the ASPEN simulation. The
>>>>>>>>> only differences I can see is that the ASPEN simulation uses the NRTL-hoc,
>>>>>>>>> whereas my simulation uses NRTL.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> The conversion reactor had zero conversion and both the PFR and
>>>>>>>>> CSTR reactors gave the error: "The given key was not present in the
>>>>>>>>> dictionary." I'm not sure what this means. I tried different thermodynamic
>>>>>>>>> models besides NRTL with no avail.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> I will send my simulation file attached.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> I would really appreciate any light on the matter.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Obrigado!
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Hector D. Perez
>>>>>>>>>
>>>>>>>>> Chemical Engineering Consultant
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
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>>>>>>>>> _______________________________________________
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>>>>>>>>> Dws...@li...
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>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
>