8 replies to this topic

[Bayan]

Hello

 

Please help me with following issue.

I have two gases. Natural gas and Sour gas. With known component fraction(constant). All the time I need to estimate z factor for different range of T and P for each gas.

 

Can you advice formula to do it more accuracy?

 

Thanks

[shvet]

You can convert gas density to Z using formula.

 

Z = P*M/8.31*p*T

 

where P is pressure in kPaa

           M is molecular weight

           p is density in kg/m3

           T is temperature in °K

 

Density of gas you can calculate using a lot of math methods using software, for example Simsci Pro II or Hysys. You can ask here for help.

[Bayan]

Sorry for misunderstanding. I need Z factor for calculating gas Volume at P and T

[serra]

you may find several Excel pages in this forum,

there are many correlations which may be useful, see for example

 

"http://petrowiki.org...r_for_sour_gas"

 

of course as suggested by shvet you may use a software (I have Prode Properties) which returns Z, density etc.

[Bayan]

I want to do all calculation in Excell.  You know I have Hysys programm, but every time to entering P and T for certain gas it's take time(We have many calculation). I want to make Excell file and calculate once all things for Sour Gas and Fuel gas(their component composition is constant). and after putting P and T to know Z and V(to know the volume of gase is the goal).

[serra]

if you know Z at regular intervals on a P-T grid you may interpolate V = ZRT/P

 

for Z (or density) if you wish to calculate accurate values a iterative solution (EOS or the correlations mentioned in my previous post) is suggested, however that may run slow in Excel,

for a fast solution you may install a process library (see my previous post) or link with a external software,

I prefer a process library but if you own a simulator then you may use that...

[Bobby Strain]

HYSYS and Excel is all you need. Hook them together.

 

Bobby

[MrShorty]

Z is used for different quantities in different contexts. In this case, I assume we are all talking about the "compressibility" factor, since it looks like we are all talking about PVT properties of fluids.

 

Two basic approaches that I see for computing compressibility (whether you use Excel or simulator or slide rule):

 

Take PVT data and plug into the basic "ideal" gas law: PV=ZnRT. Solve for Z.

 

Choose an appropriate equation of state, and solve that equation for "Z".

 

I assume that you want to use this latter approach. Since you have not specified which EOS you want to use, I will simply refer you to Wikipedia's EOS page. https://en.wikipedia...uation_of_stateThe basic approach that I see:

 

1) Choose EOS

2) Collect pure component and mixture data needed by EOS (critical properties, binary interaction parameters, EOS specific parameters, other??).

3) Solve EOS for given mixture composition, T, P to get V and or Z.

 

Of course, the details of 2 and 3 will depend on the EOS chosen in 1.

[breizh]

Hi Bayan ,

You may use the excel sheet attached to perform your work . Follow the recommendation given above  and key in the different parameters associated to the mixture .  Apply Kay's rule for pseudo critical parameters .

 

attached a data base where you can find the properties of pure components :

 

http://www.cheric.or...rop/cmpsrch.php

 

Hope this helps 

 

Breizh

Edited by breizh, 22 August 2015 - 03:29 AM.