Determining Capacity of Liquid Nitrogen Supply System

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Discussion Overview

The discussion revolves around determining the capacity of a liquid nitrogen supply system used in a thermal power plant. Participants explore the conversion of liquid nitrogen to gas under normal conditions, focusing on calculations related to density, moles, and volume at standard temperature and pressure (STP).

Discussion Character

  • Technical explanation
  • Mathematical reasoning

Main Points Raised

  • One participant seeks assistance in calculating the gas volume produced from an 8 m3 liquid nitrogen tank under normal conditions (0°C, 1 atm).
  • Another participant provides a calculation based on the density of liquid nitrogen, concluding that the tank contains approximately 6.5 tons of nitrogen, which translates to about 5.2 million liters of gas at STP.
  • A question is raised regarding the source of the mole density used in the calculations.
  • Clarification is provided about the atomic weight of nitrogen and the molar mass of nitrogen gas (N2), which is 28 g/mole.
  • A participant acknowledges a misunderstanding regarding the term "mole density," realizing it refers to molar volume derived from the ideal gas law.

Areas of Agreement / Disagreement

Participants generally agree on the calculations related to the density and conversion of liquid nitrogen to gas, but there is a minor misunderstanding regarding terminology that is later clarified. No significant disagreements are noted.

Contextual Notes

The discussion does not resolve potential uncertainties regarding the assumptions made in the calculations, such as the applicability of STP conditions to the specific scenario of the nitrogen supply system.

Who May Find This Useful

Individuals interested in thermodynamics, gas laws, or those working with cryogenic systems may find this discussion relevant.

Avis
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Im working on an exisiting Ntirogen supply system that's used to blanket boilers and pipelines etc. at a thermal power plant. I am trying to determine the capacity of the system. I have determined the size of the liquid ntrogen tank to be 8m^3 but I'm lost on how to determine the amount of gas that can be produced from the expansion of the liquid.

I'd like to assume Normal conditions. 0 celsius 1atm.

Any Ideas?
 
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The density of LN2 at its boiling point (from Wikipedia) is 0.808 g/cm^3. If you have 8 m^3, this is 8*10^6 cm^3, so this is about 6.5 * 10^6 g. This is 6.5 tons - must be a big tank! Since N2 is 28 g/mole, this is 2.3 * 10^5 moles. At STP of 0 Celsius and atmospheric pressure, each mole occupies 22.4 liters, so this would be 5.2 * 10^6 liters.
 
phyzguy said:
The density of LN2 at its boiling point (from Wikipedia) is 0.808 g/cm^3. If you have 8 m^3, this is 8*10^6 cm^3, so this is about 6.5 * 10^6 g. This is 6.5 tons - must be a big tank! Since N2 is 28 g/mole, this is 2.3 * 10^5 moles. At STP of 0 Celsius and atmospheric pressure, each mole occupies 22.4 liters, so this would be 5.2 * 10^6 liters.

Where did you come up with the mole density?
 
The atomic weight of nitrogen is 14 g/mole - this is something you look up in the periodic table. Since Nitrogen gas is N2, a mole of nitrogen gas weighs 28 g.
 
Sorry, I ment molar volume. I know realize that its from the idea gas law.

Thanks for the help, this all makes sense now!
 

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