Mixing of Liquid Ethane & Natural gas 1

[suprakash1735]

Hi,
I need to do a simulation on mixing of Liquid Ethane & Natural Gas & find out the commingled mixture property.
I modelled the same in DSWIM. The DWSIM file may be downloaded from below link. [

http://www.filehosting.org/file/details/585380/Liquid Ethane & Natural Gas Mixture.dwxml

]
Liquid Ethane:
Mass Flow rate 175 T/Hr. Accordingly I derived 3788405 Kg/d. Pressure 75 bar, Temp 25 C. Also I selected Phase molar fraction as “Overall Liquid”. Composition: C2 99.5%, C1 0.05%
Natural Gas:
Volumetric Flow rate 8 MMSCMD. Accordingly I derived 8000000 m3/d (standardised). Pressure 80 Bar, Temp 50 C. Composition: C1 94.4%, C2 3.9% rest higher hydrocarbons in proportion.
I am arriving at following result for the mixture–
Composition: C1 94%, C2 4.4% rest higher hydrocarbons in proportion.
Temp 47.47 C.
** I have used PR & SRK EOS.
My doubt is –
1. Have I made any mistake in modelling the scenario
2. Since pure Ethane is mixed, but still Ethane proportion in result mixture did not significantly increase. Did I miss something while defining the Ethane Mass Flow rate & Natural Gas Volumetric flow rate.
3. Also the pure ethane has critical pressure & temp close to 52 bar & 32 C, but when mixed with natural gas, the mixture phase envelope shows the Dew points completely in the negative side.
Pls help.

 

[apetri]

I don't know that software, to get help I suggest to provide compositions and operating conditions of each stream so that other members can verify the results with a different software,
as alternative you can simply solve the mixer in Excel with the help of a thermo library...
you may download this

http://www.prode.com/en/properties.htm

in Excel, with with Prode Properties, open the Properties Editor, define the input streams 1 and 2 with compositions and operating conditions,
then to solve the mixer write the macro
=MIXF(1,2,0)
in a cell, the results are stored in stream 1
mixers are very simple operations and providing you select the proper thermodynamic models (in Prode Properties you may select PRX, the extended Peng Robinson which is good for hydrocarbons) you shouldn't find problems...
you may wish to use Prode (or another software) to check your results, with Prode you can generate the phase envelope / diagram, as well

 

[suprakash1735]

But can i do the mixing simulation for Natural Gas & Liquid Ethane...

If you know, can u please guide..I am downloading the pride properties

 

[apetri]

yes, with Prode Properties you can solve (directly in Excel) mixers as well as complex equipments such as distillation columns etc.
of course you can use any other simulator (if you have access to one)

 

[suprakash1735]

The Prode properties seems to be not so user friendly.

Is there any other way out??

 

[don1980]

For people who use any type of simulation program, this is a very quick and easy task. Since you're not experienced with these programs, ask a colleague who is. Or ask a colleague to give you a quick tutorial on how to do it.

 

[apetri]

to give a idea of how to use the software, see the steps

define stream 1 with C1 0.944 C2 0.039 C3 0.01 NC4 0.005 NC6 0.002
P 80 Bar T 50 C Flow 255000 Kg/h (8MMCFDAY/0.77/24)

define stream 2 with C2 1.0
P 75 Bar T 25 C Flow 175000 Kg/h

with Peng Robinson standard, the calculated temperature is about 14 C

for this stream the program calculates this phase diagram

given the same inputs (compositions, operating conditions, models) you should obtain similar results from your simulator...

 

[suprakash1735]

Hi, Apetri...

Heartiest thanks..I compared the results with DWSIM..I understood my mistake, actually when solving a mixture simulation, the mass flow of the components are very important. I was wrongly feeding the simulator for Natural Gas mass flow..
I corrected the same. Precisely for this composition the density comes out to be 0.725. Using the same, I did rest of the work in DWSIM..the results are very much the same..mixture temp comes out to be 14 degC (presily as yours), also the mixture composition comes out to be C1 67% & C2 32% (presily as yours). Also the phase envelope derived from DWSIM is very much similar to that derived from Prode.

Now I rest assured that the simulators are pretty much giving the same results.
But, yes, one day I will definitely give Prode properties a try. But presently DWSIM works excellent for me..

Thanks once again..


Suprakash

 

[apetri]

glad to read that your software gives the correct results,
most memebers here are process engineers with access to different simulators (I have Prode Properties plus Simulator, others have Aspen, Promax, PROII etc.
if you need further support remember to provide all the details required to solve the problem with different software tools...