Storage tanks are often sized for the contingency where the feed source is interrupted for some length of time, say a turnaround, and you still need to deliver ammonia to some critical consumers. So find out what this interruption duration would be and build the corresponding volume into this tank.
This could be either for interruption of the flow in or out, but capability to keep one of them going with the other at zero or reduced flow.
So it could be anything. Flow in and out will help, but you need to factor in time.
do you need to size if for one hour fill or empty, or 2 or 4 or .....
How are you planning to operate? nearly empty, half full, nearly full?
If you're not the process engineer I suggest you go and talk to them.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
- Is this an Anhydrous Ammonia or Aqueous Ammonia Tank ?
- How many tanks do you need for the service ? (It is not uncommon to have two or more tanks to store Ammonia) You may want to be filling one tank while the other is in service
- What is the minimum delivery volume required by your supplier ?
- What is the maximum amount of time you might undergo no delivery ? (Consider a 3 day holiday, traffic disruption etc)
- Have you considered a used tank ? There are many on the market in the USA. Where are you located ?
- It is not too early to develop preliminary layouts - the tank must be remote from structures, there must be a truck/rail offloading station, possible fire protection
- Have you ever done this before ? (I guess here that I am asking if you are working for an MBA...)
Ammonia tanks carry a very dangerous, volatile content: Your installation will require retention walls (if small - 1 or 2 truck loads or tank car loads), or full dams and ponds if larger. Once leaking, the gasses, retention dams and pipes must be honored in the evacuation and safety plans of the customer.
Volume only is NOT the most important question to be addressed. What have asked your boss?
The mass flow in and out over a decent time period will need to be the same otherwise you will need an tank of immense size.
You simply don't have enough information to size your tank if you don't know what the purpose of the tank is or any time period involved when mass flow in is different to mass flow out.
Or for some reason you're not telling us the full story.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.