8 replies to this topic

[Mahmoud Nasr]

Dear friends is there any algorithm for calculating the ternary VLE equilibrium of a system at 50C and 1.5:2 atm
Thanks in advance

[MrShorty]

I would answer with a cautious, yes. There are many algorithms for calculating VLE of many different systems. The details of the algorithm, of necessity, depend on the system details and the thermodynamic model chosen for the calculations.

 

Are you looking for something preprogrammed, or are you looking to write your own program?

 

If you are looking for something preprogrammed, are you willing to pay for the program (such as a commercial process simulator), or does the application need to be free?

 

If you are writing your own program, are you familiar with Raoult's law, and could you program the calculation using an algorithm based on Raoult's law?

[Mahmoud Nasr]

I need to write my own program. The system is a mixture of O2 Cl2 C2H4 N2 C2H4Cl2.

[MrShorty]

Is there a specific part of writing this program that you need help with? The thermodynamics of phase equilibrium is often covered in at least one college level course. I'm not sure it is fair to expect us to recreate an entire college semester in a single internet forum post. I think it will be important to break this down to the parts that you have trouble with rather than trying to explain the entire algorithm.

 

What concepts are you familiar with in phase equilibria calculations? Can we assume that you are familiar with Raoult's law (and Henry's law, since your system is a mix of subcritical and supercritical components)? Activity coefficient equations? Equations of state and how to get PVT properties and fugacity coefficients from them? What resources (textbooks, websites, etc.) do you have access to for research and discussion of the many VLE and thermodynamic equations?

 

We'll be happy to help where we can. I think we will be better able to help if we understand where you are at in your studies and where we need to go. It will also help if, in addition to helping us understand what you already know, if you can pose specific questions about parts of the problem and where you are stuck, rather than open ended questions.

[Mahmoud Nasr]

I have some knowledge of binary systems only how to get K values and flash calculations but I want to know how to calculate the equilibrium ratios in the of multiple systems such the one I have mentioned above. You can tell me where to start. I have access to Smith book. If you have suggestions for where to start it will be helpful.

[MrShorty]

I am not familiar with Smith's book. Does he/she not talk about how to extend binary VLE calculations to ternary and higher mixtures?  I think that most if not all texts I have seen do have a VLE section specifically for binary mixtures, but they also tend to have a section that talks about extending the equations for binary mixtures to ternary mixtures.

 

What kind of algorithms are you familiar with for binary mixtures? gamma only? gamma-phi algorithms? phi-phi algorithms?

 

In many ways, extending binary algorithms to ternary and higher systems is usually straightforward. The various summations needs to be taken over components 1 through n instead of only 1 and 2, and other tedium. My suggestion for a starting place is the binary algorithms you are already familiar with.

[Mahmoud Nasr]

OK Sir thanks for your help

[Mahmoud Nasr]

OK Sir thanks for your help

[MrShorty]

Good luck. Let us know where you get stuck (if you get stuck), and we'll be happy to see if we can help.