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[carbon60]

Hello All,

I am trying to teach myself how to use the electrolyte package in Chemcad to model reactions involving electrolytes and I am having a few problems I was hoping someone could help me with.

To give a little bit of background, I am currently a student and in one of my past classes we simulated an Acrylic acid plant so I do know the basics of Chemcad as well as some fairly advanced distillation methods. however, I figure while I have access to simulation software I might as well try to learn some more on my own.

What I am trying to do to get the hang of the electrolyte package is model the neutralization of HF by calcium hydroxide so I can do some hand calcs to make sure I am doing everything correctly.

Correct me if I am wrong but I believe Chemcad automatically calculates the disassociation of acids in water at the feed stream. For example if I were to type in 49 kg HF and 51 kg water, chemcad would automatically adjust it to have the correct F- HF H+ ect.

where I am running into trouble is when I want the reaction to take place. my main question is what reactor should I be using to allow for the correct simulation of the neutralization process. I have attached a picture where I attempted to use a Gibbs. The Gibbs reactor was only able to converge under the isothermal option, but the simulation produced no calcium fluoride. Should I be using an Equilibrium reactor, and if so how would I specify the calcium fluoride reaction? Or, do I have to use a stoich reactor and specify the HF conversion. Ideally what I would like to do is simulate dumping X amount of CaOH2, HF, and water in and seeing what the final composition would be.

Thanks in advance for your help, also if anyone could point me in the direction of any good examples or tutorials for the electrolyte package it would be much appreciated.

Attached Files

•  ChemCad Question.xlsx   31.05KB   34 downloads

Edited by carbon60, 31 August 2011 - 04:48 PM.

[carbon60]

Hi all,

So after fiddling around with some other reactions (NaOH + HCl) I think I figured it out. What I found is that a component separator should be used to model this neutralization process. also, where I was running into the majority of problems is that CaF2 is not included in the electrolyte package (whereas NaCl is) so you have to make sure edit the electrolyte properties of CaF2 and type in the Heat of formation, gibbs, ect which is required for the electrolyte calculations. I just got these properties form the handbook of chemistry and physics.


as a follow up question I was wondering if anyone knows if there is a third party database or something for chemcad that includes various other chemicals or properties not normally included (our school has V 6.2)

If anyone notices that I may be going about this the wrong way please let me know any feedback is appreciated.

Thanks in advance

Edited by carbon60, 03 September 2011 - 12:38 AM.