Hello,

As I know, you need to add yourself or estimate using ASPEN the parameter DGSFRM for N2H8SO4. I'm not sure it will help you a lot, but it seems that Aspen cannot run the simulation without using this parameter.

Best regards

Thanks Loris,

Yes, I have to feed Aspen with DGSFRM data. Do you know where to get these data for different compounds?

I'm not sure PubChem has this kind of data. Still, maybe you can estimate the parameter via 'retrieve parameters' or using the estimation mode (both in the properties environment).

Maybe NIST could fill in this kind of data, or the last idea would be to give a random value and see its real impact on the process itself.

Thanks Loris Baggio

I will try PubChem or NIST.

I am also struggling to find the 'Kinetic factor' constants in specifying chemical reactions, if you have any suggestion, please

Aspen Plus databank SOLIDS has component (NH4)2SO4 or ammonium sulfate with DGSFRM of -215.362 kcal/mol (-901.075 kJ/mol). This agrees with value for Gibbs energy of formation of crystal (NH4)2SO4 given on page 2-71 in NBS tables which is -901.67 kJ/mol.

Thanks Richard Sherritt , DGSFRM problem solved!

The issue I have now is with this reaction in the REquil @ 400degC

Mg3Si5(OH)4 + 3 (NH4)2SO4 = 3MgSO4 +2SiO2 + 6NH3 + 5H2O

This is a balanced reaction but the error I got from Aspen is this:

** ERROR

BLOCK REQUIL IS NOT IN MASS BALANCE:

MASS INLET FLOW = 0.48611111E-01, MASS OUTLET FLOW = 0.48263960E-01

RELATIVE DIFFERENCE = 0.71927602E-02

CHECK STOICHIOMETRY OR MOLECULAR WEIGHTS

Should it be Mg3Si2O5(OH)4, not Mg3Si5(OH)4?