Can some one provide general naphtha composition in terms of c3, c4, c5 ...... etc in wt %. Actual names will be more useful. such as i C4 or ch, i c5 etc.
First. Do you refer to the top naphtha cut of a topping unit ?
Second. Is the FBP around 350oF as for a cat reformer feed stock ?
Third. What specific crude oil are you aiming at ?
Fourth. Compositions vary. Beyond C7 hydrocarbons are generally "named" as per their cut points; for example, on a "full-range" naphtha of Q8 crude, "pseudo" 1, 2, 3, 4, are the heavier fractions boiling 50% above 300, 70% above 310, 90% above 330 up to a FBP of 358oF, respectively, on a ASTM distillation, which converted to TBP would result in 305, 319, 346, and 378oF, respectively.
TBP cut points are available. I need very simple composition that I can plug in hysys or pro-II. Therefore I need to pick the right components and in wt frac. As far as psedo components are concerned, I have modeled them. Therfore it will be highly appericiated if you can provide some thing on the following lines:
Hysys accepts TBP cuts as input. Why do you need or want to use specific components? Anyway, that's your choice.
If you have fairly narrow TBP curves, you could simply look at boiling points to 'pick' a representative component.
Let's say you have 5.6 vol% of a 175 deg F cut.
n-C6 is 155.69 deg F
n-C7 is 209.13 deg F so you need to look at an isomer.
2,2 dimethyl pentane is 174.5 deg F for example. The wider the cut point, the less accurate this is going to be.
But you are going to obviously introduce inaccuries doing this. The resulting accuracy is going to be your decision depending on the required accurate for your needs. I would want to compare bulk properties (density, viscosity, viscosity, etc) of the ones that are important for what you want to do. If you are doing flash calcs, then you need to run some of those and see if your component mixture gives you comparible results with the TBP data.
Chevron's web pages has a fair bit of information on fuel properties and I think they have a 'typical' carbon distribution for gasoline, I'll see if I can find it for you. IF your naphtha extends over the boiling point range for gasoline, that might be a reasonable aproximation but I've not seen a cookbook method for what you are asking.
I tried simulating it based on tbp only. but when it comes back to the simulation enviorment it asks for composition again. therefore could not fig out what is happening. thanx.
Have you tried contacting Hysys or asking someone else in your company. Believe me, Hysys works with TBP data rather than needing you to 'convert' it to pure components.
