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

[Hector P. <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
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> ------------------------------------------------------------------------------
>>>>>>>> Find and fix application performance issues faster with
>>>>>>>> Applications Manager
>>>>>>>> Applications Manager provides deep performance insights into
>>>>>>>> multiple tiers of
>>>>>>>> your business applications. It resolves application problems
>>>>>>>> quickly and
>>>>>>>> reduces your MTTR. Get your free trial!
>>>>>>>> https://ad.doubleclick.net/ddm/clk/302982198;130105516;z
>>>>>>>> _______________________________________________
>>>>>>>> Dwsim-users mailing list
>>>>>>>> Dws...@li...
>>>>>>>> https://lists.sourceforge.net/lists/listinfo/dwsim-users
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
>