Heat Capacity and Viscosity of Ethane/Propane Mix 1

[SuperG]

I am modeling a pipeline, which carries an Ethane/Propane Mix. I cannot seem to find any heat capacities or viscosities for a standar mix (80/20).

Can anyone help?

 

[TD2K]

Do you have access to a process simulator? Pro/II or Hysys would do it.

Alternatively, you could look at 'Properties of Gases and Liquids' Reid, Prausnitz and Poling. They have methods on estimating those properties. Viscosities of mixtures though can be highly non-ideal.

 

[TD2K]

I likely should have added (no coffee yet this morning when I wrote this) that although the viscosity of mixtures can be highly non-ideal (meaning the viscosity of a mixture can be much more or less than the viscosity of either pure component), a propane/ethane mixture shouldn't fall into this group IMO.

How are you modeling the pipeline? What is your expected range of operating pressures and temperatures?

 

[KernOily]

For close estimates you can use a weighted average of the pure component properties based on composition, i.e.:

mixture viscosity = 0.8(C2 viscosity) + 0.2(C3 viscosity),

since your composition is 0.8 [C2] and 0.2 [C3]. The pure component viscosities can be gotten from Fig. 23-30 from the GPSA Handbook, 10th ed.

The easiest way is to use a process simulator like HYSYS, PIPEPHASE, PRO-II, Aspen, ChemCAD, etc. as TD2K said. Maybe if you have a buddy that works for an engineering contractor, you can call him up and get him to do this for free since it takes about 30 seconds to do this in PIPEPHASE...

Hope this helps! Thanks!
Pete
P. J. (Pete) Chandler, PE
Principal Engineer
Mechanical, Piping, Thermal, Hydraulics
Processes Unlimited International, Inc.
Bakersfield, California USA
pjchandl@prou.com

 

[SuperG]

PipePhase? Crud, I have that...just started using it, but I couldn't figure out how to determine the properties I am looking for. On the other hand, I found someone in the company who has HYSIS, and he calculated the numbers for me...thanks to all for the help.

So, Pete, how do I go about using Pipephase for this problem?

 

[TD2K]

For pipephase, you'd have a 'source' or 'sources' where you define (typically) the flow rate, composition, pressure, temperature, etc. Pipephase then calculates whether the mixture is liquid, vapor, a mixture and all other physical properties it will needf (it's also calculating these properties at each pipe location to do the equilibrium and heat/mass transfer calculations).

Check under your output options, there should be something that allows you to print out the physical properties. I haven't used Pipephase for a few years and I suspect it's changed significantly but this information will be there.

 

[SuperG]

Yeah, it's the composition part I was having a problem with...I will give SSI a call and get that out of the way. Thanks for the help!

 

[TD2K]

What's your question on the composition part? Pipephase defaults to either mol%, wt% or lv% (sorry, can't remember which one) but you can over-ride it with other units.

 

[stanier]

Try AFT's Chempak. This is a low cost solution for 700 chemicals.

 

[KernOily]

Yeah, it's the composition part I was having a problem with...I will give SSI a call and get that out of the way. Thanks for the help!

It's easy-greasy:

Just build a model with one source, one sink, one junction, and one foot of 24" pipe from the source to the junction and from the junction to the sink. Set the heat transfer to isothermal. All you are interested in is fluid properties so who cares about hydraulics or heat transfer.

Set the simulation type to Network and the fluid type to Compositional.

Pick your components from the tables.

Click on the source and type in your composition, P, T, and a flowrate of 1 lb/hr. Set your actual process conditions at the sink: fixed P, e.g. 120 psig, estimate the rate of 1 lb/hr, and at the source, fix the rate at 1 lb/hr and estimate the pressure at something a little higher than your fixed sink pressure, e.g. 121 psig.

Run the model and look at the flash report at the junction. The physical, thermo, and transport properties are printed therein. You're done! E.T. about 2 minutes for you, about 30 seconds for me since I do this all the time... Hope this helps!


Thanks!
Pete
P. J. (Pete) Chandler, PE
Principal Engineer
Mechanical, Piping, Thermal, Hydraulics
Processes Unlimited International, Inc.
Bakersfield, California USA
pjchandl@prou.com

 

[SuperG]

Thanks, Pete! I can do this on a regular basis, now, and check some previous models for accuracy, not to mention the future models I have waiting for me...

 

[KernOily]

Hey, it ain't no thang, dude.

You also know that PipePhase can do your pipeline hydraulics for you...right? And sensitivity/case studies for different line sizes, wall thicknesses, ambient temperatures, etc. I should be a SimSci salesman... Wonder if I get a commission?

The method I outlined above is useful only for generating physical/thermo/transport properties. Pipephase is obviously MUCH more capable than just that little task. It better be, considering how much it costs! It's sort of like swatting a fly with a shotgun.
Thanks!
Pete
P. J. (Pete) Chandler, PE
Principal Engineer
Mechanical, Piping, Thermal, Hydraulics
Processes Unlimited International, Inc.
Bakersfield, California USA
pjchandl@prou.com

 

[chem55]

Hi..!

Check in Perry - Handbook of chemcial Engineers. PREDICTION OF CORRELATION OF PHYSICAL PROPERTIES. From there you can calculate the viscosity.

regards,
chem55