In Ethylene/Olefine plant, there is a mixture of hydrocarbons and water in a wide range of temperature and pressure (Temperature: 0- 500 degC and pressure 0-45 barg). What is the best thermodynamic model which can predict thermodynamic/transport properties with good accuracy?
Which EOS can predict thermodynamic/transport properties for hydrocarbon + water mixture in hot section (max temp= 850 degC)?
Thanks for your reply Luis. Temperature has a wide range. max temp is 850 degC and sometimes temp is 210 and mixture is not always in Supercritical region.
You will need an extended BWR equation of state like the one suggested by Nishuimi and Saito, J. Chem. Eng. Data, 8, 5, p. 356, 1975 https://www.jstage.jst.go.jp/article/jcej1968/8/5/8_5_356/_pdf
Note the higher order temperature terms. He was SPOT ON. Pitzer also published "Higher order temperature terms are needed for at low reduced temperature". That's when he introduced the 1/T^8 into expressions for second virial. Nishuimi was right too. He added even higher order temperature terms not only on the second virial, but also on the third.
Then you need better mixing rules. Once you derive the expression for the second and third virial coefficients. You can set VIRIAL BASED mixing rules. as follows.
V2mix = Sum Sum Xi Xj V2,i,j ( 1- kij)
Nothing unusual about that but the mixing rule for the third virial is a triple summation
V3mix = Sum Sum Sum Xi Xj Xk V3,i,j,k (1 - Li,j,k)
The Li,j,k is a ternary interaction parameter. But offers two additional binary interaction parameters L1,1,2 and L1,2,2. You will NEED those to fit narrow boiling point systems such as ethylene ethane and propylene propane.
See if you can find my dissertation "Virial based mixing rules in a modified BWR equation of state". Or, if you harass me enough, I will upload it here someday.
I also like the LKP. Nishuimi has his own LKP but with the higher order temperature terms. I will be looking at that as soon as time allows.
I hope you find this helpful.
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