12 replies to this topic

[muthukmaar]

I have used Aspen Hysys with Peng Robinson Equation as the fluid package to get the volume of the flue gas containing N2,O2,CO2,H2O,SO2,NO2 at different temperatures by specifying the temperature , pressure ,flow rate , temperatures in an material balance stream .y question is that is the data obtained acceptable

[PaoloPemi]

it is difficult to answer such a generic question, you should provide additional information about your application,

if that may help, I am able to estimate the flue gas flow with my copy of Prode Properties following this procedure

1) estimate fuel gas mass flow from burner heat duty, burner efficiency and fuel gas calorific value (with Prode, you can obtain these values according ISO 6976 2016 standard or solving the chemical reactions) and get flue gas flow (as result of combustion process)
2) estimate flue gas volumetric flow at specified (pressure, temperature) conditions , normally P = atm, T = measured , since you can guess the composition a EOS such as Peng Robinson or maybe also ideal model should be Ok

Edited by PaoloPemi, 27 May 2019 - 03:32 AM.

[muthukmaar]

we have a top fired reformer which is Naphtha Fired, the negative pressure in the reformer is maintained by an ID Fan.The Fan discharges the Flue gas containing Nitrogen 82%, Argon 1.9%, Oxygen 2.7%, CO2 5.8% and Water 7.6% at 320mmWC.g at 130 degree Celsius. I have to find the Volume of the Flue Gas at various temperature and Pressure at constant Naphtha and Combustion Air flow.

My question is can I use Peng Robinson Equation to get the Volume at different Temperature and Pressure by specifying the Temperature,Pressure, Mass flow rate and composition in the Material stream 

[thorium90]

PR is a reasonable EOS for finding these properties.

But is it really necessary?

The molar volume of an ideal gas at 273.15 K and a pressure equal to 1.00 atm is 22.414L. You can use PV=nRT to find the volume at any other temperature and pressure.

This gas of yours I believe would be sufficiently close to ideal to give a reasonable estimate.

I found a nice website for you to read to learn more.

https://socratic.org...gas-224-l-at-st

[muthukmaar]

Sir the link isn't working

[Bobby Strain]

Surely you can follow the trail without further help.

 

Bobby

[thorium90]

Curiously the link doesnt work if its directly clicked.

Anyhow, I took a screenprint for you.

You can also google molar volume of gas.

Attached Files

•  MOLAR VOLUME.png   79.75KB   2 downloads

Edited by thorium90, 28 May 2019 - 12:19 AM.

[muthukmaar]

Thank you Sir

[breizh]

Hi ,

You may use this tool to support your work

 

https://www.questcon...perties-fluids/

 

Good luck

Breizh 

[muthukmaar]

Dear Sir
This tool doesn't contain oxygen argon etc.,

[PhilippM]

I don't really see the problem with just using the gas laws instead of HYSYS in this case, assuming of course the gases do not condense and/or react with each other.

If I'm not mistaken though (and  also depending on the temperature you're looking at), some of them condense and do react with each other (just copying the next three paragraphs from Wikipedia here, as my knowledge of the chemistry of flue gas is a little rusty):

 

-NO2 exists in equilibrium with the colourless gas dinitrogen tetroxide (N2O4)

 

-It hydrolyses to give nitric acid and nitrous acid:

2 NO2 (N2O4) + H2O → HNO2 + HNO3

 

-The sequential oxidation of sulfur dioxide followed by its hydration is used in the production of sulfuric acid.

2 SO₂ + 2 H₂O + O₂ → 2 H₂SO₄

 

So you probably first need to check what gases you are actually dealing with, your two posts are not consistent in this regard (N2,O2,CO2,H2O,SO2,NO2 vs. Nitrogen, Argon, Oxygen, CO2 and Water) 

Edited by PhilippM, 31 May 2019 - 04:31 PM.

[breizh]

Hi muthukmaar,

I'm happy to help when I see people doing a minimum work .Your statement above is totally wrong , did you check the calculators , in particular "other thermodynamic properties" ?

Engineering is about hard work .

 

Good luck

Breizh

[thorium90]

Would like to point out that N2,O2,CO2,H2O,SO2,NO2 and Nitrogen, Argon, Oxygen, CO2 and Water are actually really the typical stuff found in reformer flue gas... In fact, for any flue gas actually...

The N2, O2, Ar, CO2, H2O are actually components found naturally in the air that was used in the combustion. The NOx and SOx are due to the combustion process (which is related to combustion temperature and burner design) and the sulphur content of the fuel that was used.

 

Anyhow, muthukmaar, I think molar gas volume and ideal gas law is the solution to your problem.