7 replies to this topic

[Chem_engg1996]

Hi all,

 

          I'm trying to calculate the inbreathing and outbreathing flowrate for our storage tank using API 2000. The component we are using is molten salt with 53% KNO3, 7% NaNO3, 40% NaNO2. The tanks operating pressure is 0.01 bar_g and the maximum operating temperature of the tank is 436.7 °C. As per API 2000 7th edition, the outbreathing flowrate is equal to the filling rate in to the tank. In my case the liquid in rate is 155.66 m3/hr, so the outbreathing flowrate is 155.66 m3/hr. As per the standard, for tanks operating above 49°C. the calculated flow is actual vapor flow and it needs to be converted to the air equivalent flow. Please help me with the conversion. my tanks design pressure is 0.02 bar_g and the design vacuum is -0.0041 bar_g.

Edited by Chem_engg1996, 20 February 2025 - 11:24 AM.

[Pilesar]

In API 2000, review Annex D.9 'Expressing Relief Requirements in Terms of Equivalent Air Flow' which details how to do the conversion in question.

[Chem_engg1996]

Hi Pilesar,

 

                   Thank you for you reply .. yea i found the equation already but i already have the flow calculated in m3/hr. but in the equation it asks for Wfl. which is the mass flowrate. and there is a formula given for that too, in that formula, Aeff needs to be calculated and i used API 520 to calculate the Aeff. is that correct. Mine came out 0.75 Sq.Inch.. and im stuck calculating the isentropic coefficient.

[latexman]

. . . and im stuck calculating the isentropic coefficient.

It’s the isentropic coefficient of the gas/vapor blanketing the tank. I’m guessing it’s nitrogen or air in your case, but I’m not sure. You should be able to find isentropic coefficients on nitrogen or air quite easily. It doesn’t vary much with temperature being it’s Cp/Cv.

[breizh]

Hi,

For those interested API 2000 where you can find the calculation.

Isentropic coefficients are easily found using your favorite engine, don't be lazy!

As an approximation you can use the gas perfect law to calculate the gas density @ condition (T,P)

Breizh

 

Attached Files

•  API 2000 7th EditionBallot 2013 edition.pdf   4.94MB   14 downloads

[_1angelia23]

Hi all,

I'm trying to calculate the inbreathing and outbreathing flowrate for our storage tank using API 2000. The component we are using is molten salt with 53% KNO3, 7% NaNO3, 40% NaNO2. The tanks operating pressure is 0.01 bar_g and the maximum operating temperature of the tank is 436.7 °C. As per API 2000 7th edition, the outbreathing flowrate is equal to the filling rate in to the tank. In my case the liquid in rate is 155.66 m3/hr, so the outbreathing flowrate is 155.66 m3/hr. As per the standard, for tanks operating above 49°C. the calculated flow is actual vapor flow and it needs to be converted to the air equivalent flow. Please help me with the conversion. my tanks design pressure is 0.02 bar_g and the design vacuum is -0.0041 bar_g.

Download the study about venting in the egineering magazine in link below and you find the answer
https://www.linkedin...ublic_post-text

Edited by _1angelia23, 06 March 2025 - 05:11 PM.

[breizh]

Thanks, Angelia, for supporting the community.

 

Breizh

[_1angelia23]

My pleasure, Breizh. I am just trying to learn from your knowledge and experience since we have experts in process engineering in this forum