5 replies to this topic

[mohsan]

I want to know the total quantity of Nitrogen required for purging of 10160 m³ Ammonia Storage tank (First for ammonia purging and later for Air displacement). Any one have some experience regarding decommissioning and recommissioning of Atmospheric pressure Ammonia storage tank (at -33 ^oC) please also share essential techniques and care required for it.

Regards:

Mohsin

[Rahimzadeh]

Dear Mohsan:
As rule you need purge your tank with four time of your tank volume, approximate 40000 standard cubic meternitrogen.

best regards
M.R.Rahimzadeh

[S.Chittibabu]

Refer http://www.cheresour...r-inertization/

In the spread sheet attached, instead of Oxygen 21% make assumption of 100% since no other property of fluid involved other than volume percent to be swept. Whether ammonia or Oxygen the purpose is to replace the same with Nitrogen.Since it is going to be low pressure operation Compressibility factor has no impact.. Final value after purging needs some value input in the cell (say 0.0001 %) to get result, note that TLV of ammonia is 25 ppm, other wise the Nitrogen required value does not come. It gives approximate volume of Nitrogen required to carry out purging operation.

Edited by S.Chittibabu, 22 September 2012 - 07:23 AM.

[breizh]

Hi,
The "beauty " with NH3 is that it smells at very low concentration like 5 ppm . Vessel entry permit and hot work permit are mandatory .

An other resource to support your query :

http://www.eng-tips.....cfm?qid=216942


Hope this helps

Breizh

Edited by breizh, 22 September 2012 - 12:06 AM.

[mohsan]

Thanks to all for your much helping response. Will it be the same quantity of nitrogen required for both cases, first to displace ammonia and then to Air as both have different densities and different mixing properties with nitrogen.

Mr. M.R.Rahimzadeh can you please mention the rule used for calculations. Thanks again.


Regards:

Mohsan

[breizh]

Moshan,

To dsiplace ammonia with N2 , let you perform the calculation starting from 100% NH3 until a few ppm NH3
To displace O2 , you should calculate starting from 21% of O2 until very little content of O2 ( let say 50 ppm) .
Don't forget , calculation is an estimation only and you need to check the content performing snif test with meter calibrated !

Breizh

Edited by breizh, 22 September 2012 - 08:50 PM.