4 replies to this topic

[LiveFree]

Hi All,

I am currently working on a proposal for a new unit and am requested to provide ASTM-D1837 data to the customer based off the simulation for a n-butane stream. With HYSYS, we cannot directly pull this information from the simulation. Does anybody have a solution?

D1837 is the measure of the least volatile component measured in terms of the 95% evaporated temperature. There is also a vapor pressure limitation applied. Does this mean I can run my butane stream through a flash drum at different temperatures until 5% of the least volatile component remains in the liquid stream?

Thanks in advance

-J

Edited by LiveFree, 10 January 2013 - 01:49 PM.

[Propacket]

Use Boiling Point Curve Utility of Hysys. It will give what you need.

[Pilesar]

Your question:
"Does this mean I can run my butane stream through a flash drum at different temperatures until 5% of the least volatile component remains in the liquid stream?"

The answer is "NO!"
The temperature reported is the temperature at which 5% of the TOTAL remains in the liquid phase. This is a lab test and the assumption is the composition is not known to begin with. So the test attempts a quick and easy method to determine the heavy portion without expensive analysis. So you boil the material off until just 5% is left and report the temperature. Make sure you understand the lab test procedure, then use a flash in the simulation. Just set the vapor fraction you need and the flash pressure and the simulator will give the temperature.

[Pilesar]

Lab distillation tests can sometimes be tricky to model precisely depending on pressure conditions and whether they are boiled under reflux. What is in the vapor phase during the test in the lab? Is it only the vapor phase of the sample or is it air? Does it even matter? Here is where you should understand the lab procedure and model it just like any other process. Sometimes short cuts are no problem.

[LiveFree]

Thanks for the responses! I had a problem with the verbage used in the ASTM D1837 document. It stated that it is a measurement of the least volatile component left in the sample which incorrectly led me to believe they were 'somehow' testing for that component. Didn't make sense to me how the lab could test for a component remaining with a boiling point apparatus. Thank you for clarifying.

Also, how is this different than the D86 test? Can I use D86 results pulled from HYSYS Boiling Point Utility? Both tests are performed at plant atmospheric conditions, maybe one test corrects to 1 atm and the other does not? I've used D86 data working in both design and operations, but have never used this D1837.

Edited by LiveFree, 11 January 2013 - 11:16 AM.