3 replies to this topic

[Tom Berenger]

Hi all,

 

I am trying to estimate the flue gas requirement for a proposed plant. I have been able to determine all FG needed for all processes except tank blanketing purposes.

 

People have directed me to API 2000, but it doesn't give you the blanket gas needed. API 2000 is used to calculate vent sizes and flowrate.

 

Can anyone explain how I can estimate the daily blanket gas requirement for tanks? Currently, I am estimating the daily withdrawal from the tanks and using that volume as the requirement. For example, if 10 pounds of slop was pumped out a day, the blanket gas required will be 10 pounds converted into cubic ft. Same thing for amine and glycol (using amine and glycol make-up values from promax simulations). However, I am coming up with a small value - 60 cubic feet a day.

 

Is my approach right? Does the figure look reasonable for a 60 mmscfd plant? Make-up of amine is 1.12 lb/hr, glycol is 2.85 lb/hr, water is 144.53 lb/hr and slop is 0.55 lb/hr. Using their densities, I converted into cubic feet/day. Density for slop is 62.06 lb/cubic ft.

 

Thank you all for your help.

[proinwv]

Dayo,

 

You are on the right track. It is simply a volumetric transfer. Calculate that way. Cubic feet draw off=cu ft of gas required. Then look at the effect of cooling of the tank due to atmospheric temperature changes and add that.

 

The trick is having enough information to be able to look at these factors and know the combined maximum rate at any time. I don't believe that cu ft / day is meaningful as you need to know the instantaneous requirement. Don't average it over 24 hours.I would add a factor of safety to the estimate, probably about 50%, but then your knowledge of your process and future estimates of operation would give you more insight.

 

Paul

[Erwin APRIANDI]

Hi Dayo Ajibola,

 

Tank blanketing is require to replace the amount of volume which is transfered from the tank,

in API STD 2000 you will find the inbreathing requirement of air or fuel gas in Nm3/h of m3/h liquid flow

 

The data is available for each different characteristic of fluid store in the tank, by this you can calculate the

required flowrate of air or fuel gas require to displace the volume of liquid which is taken from the tank.

 

The tank venting is required to ensure the tank integrity during loading and offloading.

 

Hope you understand

[jmouendo]

Hi,

 

I have to design a blanketing system for a tank farm and I'm facing the same difficulties as those mentioned years ago by a member whose post still hasn't been replied:

http://www.cheresour...ack-protection/

 

Please, could someone help?

 

Moreover,  using inbreathing requirements flow rate equations of annex F in API Standard 2000, I find myself with flow rates that don't match with the flow rates calculated in accordance with 4.3.2. of that same standard; which flow rates should I consider for my design?

 

Finally, can someone explain the following part F.2 sentence: "To dermine the amount of reserve inert gas, the volume of the applicable parts in the piping system (i.e. up to the air separation unit) should be considered". Why should I determine the amount of reserve inert gas if I plan

to install a nitrogen generator for example?

 

Please, I need your help.

 

Regards,

 

Jesus