3 replies to this topic

[alokjaiswal]

Dear all,

Please find attached an Excel Sheet wherein I have tried to calculate the Venting capacity of Pressure Safety Valve for Double wall double integrity Ammonia Storage Tank. I tried to calculate the capacity of Venting as per API-2000 for the case when there is fire around the Tank. Calculation have been done for FPS and SI unit system. However, both the answer are different. I am not able to spot the error in my calculation. I am also not sure whether my calculation is correct. Please guide me in correcting the Excel sheet.

Alok

[alokjaiswal]

By mistake the Excel sheet ws not attached. Please find it here.

Alok

Attached Files

•  Vent valve capacity.xlsx   12.37KB   189 downloads

[Bauherr]

Dear all,

Please find attached an Excel Sheet wherein I have tried to calculate the Venting capacity of Pressure Safety Valve for Double wall double integrity Ammonia Storage Tank. I tried to calculate the capacity of Venting as per API-2000 for the case when there is fire around the Tank. Calculation have been done for FPS and SI unit system. However, both the answer are different. I am not able to spot the error in my calculation. I am also not sure whether my calculation is correct. Please guide me in correcting the Excel sheet.

Alok

Dear Alok,
I do think the mistake is due to the units of vaporization heat in SI (cell I12 of your spreadsheet). Vaporization heat in the API 2000 formula is in J/kg, not in kJ/kg. You have to multiply by 1000 the vaporization heat value.

Cheers
Stefano

[S.AHMAD]

The mass flowrate should be Heat absorbed (Q) / Latent Heat of vaporization
1. British Unit
W = 64431391 x 0.05 / 587.826 =5480.5 lb/h or 2485.5 kg/h
2. SI Unit
W =(18882626/1000) x 3600 x 0.05 / 1367.283 = 2485.85 kg/h
3. Even-though not exactly the same but very close
4. Pls take note that your equation for NM3 conversion is incorrect.

Edited by S.AHMAD, 05 December 2012 - 02:24 AM.