What is the energy content of natural gas on an LNG transporter?

[Teodor Xypolitidis]

My brother is working on an LNG transporter and I would like to know how much energy there is in the LNG the ship is transporting, here is the info I got :
Methane ISO6974 99.8518 mole%
ethane 0.0137 mole%
propane 0.0000 mole%
i-butane 0.0000 mole%
n-butane 0.0000 mole%
i-Pentane 0.0000 mole%
n-Pentane 0.0000 mole%
c6+ 0.0000 mole%
Nitrogen 0.1345 mole%
Carbon Dioxide 0.0000 mole%
Oxygen 0.0000 mole%
The pressure in the tank is 160 mbar and the ambient pressure is 116 mbar.

 

[Bystander]

Liquid water or water vapor?

 

[russ_watters]

How much methane is in the tanks? You can Google for the combustion energy (per pund, kg, et,). If you want, you can add the energy to liquefy it, but that's a small fraction.

 

[Nidum]

https://en.wikipedia.org/wiki/Energy_density

https://en.wikipedia.org/wiki/LNG_carrier

 

[Teodor Xypolitidis]

How much methane is in the tanks? You can Google for the combustion energy (per pund, kg, et,). If you want, you can add the energy to liquefy it, but that's a small fraction.

I have written the info about the consistency of the natural gas the % of methane etc but I don't know how to calculate it, I want to know about this exact percentages and these pressures

 

[Teodor Xypolitidis]

Liquid water or water vapor?

what do you mean by that ?

 

[russ_watters]

I have written the info about the consistency of the natural gas the % of methane etc but I don't know how to calculate it, I want to know about this exact percentages and these pressures

No, I mean total volume or mass - you may as well assume it is 100% methane. It is a simple multiplication exercise if you have the mass and the energy per unit mass.

 

[russ_watters]

what do you mean by that ?

If you burn something and then condense the water out of the combustion products, you get about 20% more energy. That's referred to as the higher (as opposed to lower) heating value.

 

[RobS232]

The energy of combustion of gas phase methane is available in a reference book - look it up. But you first have to covert the LN2 in the tanks into gas phase methane. That is energy absorbe, and a loss. There are tables with that info, too. The combustion products are gaseous H2O and CO2. Forget about condensation.

 

[JBA]

What are you trying to actually determine, is it the amount of BTU's that will be delivered at the vessel's destination?