Using Electrolytes in HYSYS

I regularly get questions concerning modelling aqueous solutions in HYSYS, are some tips on how to do that. First of all: You do NOT need any  additional license to use this feature. Aspen Properties is part of the base HYSYS license. 

Below is the description of how to create a simple case with electrolytes:

Start HYSYS

Create a new case

Select the “Aspen Properties Databanks” radio button and then add a component list

Add a couple of components: H2O, HCL, CO2, NAOH, CH4 (for example)

Close the component list and go to the fluid package tab

Add a Fluid package and at the top select “Aspen Properties”

From the list that appears, select Electrolyte NRTL

IT IS VERY IMPORTANT NOT TO SKIP THE NEXT STEP!!!

Click on the “Electrolyte Wizard” button

Uncheck “Salt Formation” (this doesn’t work well in HYSYS for the moment)

Click the “Get Reactions” Button and click OK

Close the fluid package view and go to the simulation environment

It will take 15 seconds or so before you get to the simulation environment

Create a stream and enter pressure, temperature and flow

Enter a composition, please note that you should NOT enter anything for the ions, ONLY enter compositions for the molecular species

Look at the vapour and liquid compositions and also at the properties of the liquid and the pH value for example.

As mentionned above, you do not enter ionic concentrations. So, if the analysis you have expresses the water composition in terms of ions, you'll have to do a little prep work before you put this in HYSYS. Put your ionic composition in an Excel Spreadsheet and make an ion balance so you cna recombine your ions back into salts. Normally, NaCl is the main part of your salts, so leave the Na+ and Cl- ions until last to make up the balance. If you want I can Email you a sample Excel sheet. It is important to do a bit of extra analysis and eliminate the ions you do not really need for your purpose. If you use the full list like below, you case will calculate very slowly because of all the potential reactions involved. So do not be scared to dump some of the ions, especially if what you are interested in are really just pH and density for example.