Calculate CFM on Hydrogen Vent Pipe

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  • Thread starter Thread starter Chad Pulliam
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    Cfm Hydrogen Pipe
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Discussion Overview

The discussion revolves around calculating the amount of hydrogen lost during venting from a large hydrogen storage tank. Participants explore the parameters affecting the calculation, including pipe dimensions, pressure changes, and ambient conditions. The scope includes technical reasoning and exploratory calculations related to gas flow and venting processes.

Discussion Character

  • Technical explanation
  • Exploratory
  • Debate/contested

Main Points Raised

  • One participant seeks to calculate hydrogen loss during venting from a tank that vents at 150 PSI, with pressure dropping to 120 PSI over a duration of 2 to 5 minutes.
  • Another participant asks for additional information, including the size of the storage tank, ambient temperature, length and fittings of the vent pipe, and how hydrogen is replenished.
  • A participant provides details about the tank holding 2 million cubic feet of hydrogen, the outdoor temperature range, and the venting setup, including a 20 ft pipe with a 90-degree fitting and a vent valve.
  • There is a question regarding the pressure at which the 2 million cubic feet of hydrogen is measured and whether it is at standard temperature and pressure (STP).
  • Clarification is sought on whether the 2 million cubic feet refers to the actual volume of the tank or another value.

Areas of Agreement / Disagreement

Participants have not reached a consensus on the specifics of the tank's capacity or the conditions under which the hydrogen volume is measured. Multiple viewpoints regarding the calculation parameters and their implications remain present.

Contextual Notes

There are unresolved assumptions regarding the pressure rating of the tank and the exact conditions under which the hydrogen is stored and measured. The discussion does not clarify the relationship between the tank's volume and the venting process.

Chad Pulliam
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I have a large hydrogen storage tank that vents when the pressure exceeds 150 PSI. I am trying to get a rough calculation of how much hydrogen we are losing. I know it is a 2 inch pipe and the pressure drops from 150 PSI to 120PSI. The venting lasts between 2 and 5 minutes. How do I calculate how much hydrogen I am losing?
 
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Chad Pulliam said:
I have a large hydrogen storage tank that vents when the pressure exceeds 150 PSI. I am trying to get a rough calculation of how much hydrogen we are losing. I know it is a 2 inch pipe and the pressure drops from 150 PSI to 120PSI. The venting lasts between 2 and 5 minutes. How do I calculate how much hydrogen I am losing?
1. How big is your storage tank?
2. What sort of ambient temperature is present when the tank vents?
3. How much 2-inch pipe is there from the tank to atmosphere? Are there any fittings (valves, filters, elbows, tees, etc.) in this vent line?
4. After the tank vents, how is the hydrogen replenished?
5. What is the set pressure point on the vent valve?
6. What's the pressure rating of the tank?
 
1. Tank holds 2 million cubic feet of hydrogen
2. Tank is outdoors so ambient can be any temperature in this area ( -10F to 100F )
3. 20 ft of pipe straight up with a 90 as it comes out of the tank and a vent valve.
4. Truck delivery
5. 150 PSI
6. Not sure of the pressure rating but approved for storage of liquid hydrogen.

Thanks for your help
 
At what pressure are these 2 million cubic feet? Atmospheric?
And the tank can hold them at 150 PSI?
 
The hydrogen is stored as liquid similar to a liquid propane tank with vapor that builds on the top.
The vapor in the tank is allowed to reach 150 PSI before venting.
I am curious how many cubic feet we lose each time the tank vents.
2 inch vent line for 2-5 minutes.
 
Chad Pulliam said:
1. Tank holds 2 million cubic feet of hydrogen
2. Tank is outdoors so ambient can be any temperature in this area ( -10F to 100F )
3. 20 ft of pipe straight up with a 90 as it comes out of the tank and a vent valve.
4. Truck delivery
5. 150 PSI
6. Not sure of the pressure rating but approved for storage of liquid hydrogen.

Thanks for your help
I need some clarification on the tank capacity:

Is this 2 million ft3 of hydrogen measured at STP? Does the tank have an actual volume of 2 million ft3 or some other value?
If some other value, then please provide the actual interior volume of the tank.
 

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