4 replies to this topic

[jojojojoanna]

Hello,

 

I'm currently doing a simulation on the separation of CO2-water-methanol in Hysys. I'm using the fluid package of NRTL. Since the fluid package lacks BIPs, I searched on journal papers and research papers, whereby they usually give me in the form of t12 - NRTL model binary interaction parameter, is this t12 equivalent to the aij or bij in aspen hysys?

[breizh]

Hi ,

Let you drop a message to MrShorty , he is the expert.

Good luck

Breizh

[MrShorty]

Kind of you to say so, Briezh. My attempts to con the internet into thinking that I know a little thermo appear to be working .

 

I am not intimately familiar with the internal details of Aspen Hysys, so you will need to check with their documentation to be sure. Wikipedia's article for the NRTL model suggests a few different ways to get tij temperature dependent https://en.wikipedia...wo_Liquid_model

 

I am used to seeing the tij=Dgij/RT or the Antoine type equations tij=Aij + Bij/T + .... Check with Aspen's documentation to see what form they like to use for tij. Decide how many parameters you need to adequately "fit" the literature tij's, and then regress or solve for the temperature dependent parameters.

[jojojojoanna]

Hi,

I am currently using CO2-Methanol Bip values of NRTL obtained from research paper for my Aspen Hysys simulations. The literature provided the value as tij and I converted it to Aij and Bij using tij=Aij + Bij/T. I wish to validate these values using P-xy diagram in Hysys such that the P-xy diagram from HYSYS will be similar to the P-xy provided by the research paper.

Following the research paper P-xy, I plotted various CO2 and methanol ratio at T = 18 ^oC and P = 0 to 100 bar. However, the P-xy I obtained was 0 for all x, I get an error stating "Utilities Critical Properties - Pure CO2 is not available with the property package being used". 

[MrShorty]

I do not have enough familiarity with Aspen Hysys to know what that error means. Other than many would prefer a phi-phi model rather than a gamma-phi model for MeOH/CO2, I see no reason why Aspen Hysys should have trouble with a gamma-phi model for MeOH/CO2.

Showing my ignorance for the Aspen Hysys environment, is it possible that they have arbitrarily written this preference into their code so that it will not use a gamma-phi model for CO2 systems?