5 replies to this topic

[sanchez]

Hi

 

how can I convert methane (CH4) gas unit from m3 to liter at 150bar?

 

for example, 6m3 of methane gas at 150bar is equivalent to what value in liter?

 

thanks

[Art Montemayor]

This is a pretty basic, 1^st year ChE course topic.  However, you are lacking an understanding of what you request.  When dealing with gases or vapors, you must state the actual conditions (temperature & absolute pressure) of the fluid OR state the equivalent “standard conditions” volume of that fluid.  Of course, if you use the latter method, you MUST identify the standard conditions you are using.

 

You fail to tell us any of the above plus you don’t advise if you want to convert to a LIQUID volume equivalent.  The unit of liter is traditionally reserved for liquid volumes, not gases, in engineering.  Chemists use liters indiscriminately.

 

[sanchez]

Hi

 

Thanks for your explanation

 

I am actually wanted to do a price comparison between methane and CNG (compressed natural gas)

 

the cylinder tank of CNG in my lab shows the capacity of 70L

 

while methane cylinder, they put in m3

 

I found a converter tool by Linde http://hiq.linde-gas...ools_gasconvert

 

also this website http://www.navanacng.com/faq.php#9 convert liter to m3 of CNG

 

but I want to know what are the equation and data that I needed to do this

[sanchez]

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in argon cylinder it stated 7.2m3 which equal to 47L

 

yea, maybe I should ask how to convert to a LIQUID volume equivalent. sorry about that

 

anyone can help me how to do it?

[MrShorty]

When I cannot remember the conversion factor for L to m3, here's how I work it out:

 

volume = length * width * height.

1 m3 is a cube measuring 1 m on each side. V=1 m * 1 m * 1 m = 1 m3

1 m is 100 cm, so 1 m3 is also a cube measuring 100 cm on each side. 100 cm * 100 cm * 100 cm = 1E6 cm3

1 cm3 = 1 mL

there are 1000 mL in 1 L.

 

Assuming we are talking about converting m3 of gas at a given T and P to L of gas at the same T and P, then that should be it. If T and/or P are also changing as part of the conversion, then you will need a suitable EOS to handle the compression/expansion part of the calculation.

[thorium90]

While MrShorty is right in the numbers for conversion, he has failed to realise that 47L is referring to liquid volume and the 7.2m3 is referring to the gas volume. The problem is not about converting L to m3. Evidently 47L is not = 7.2m3.

 

I would like to refer Mr Sang to the following spreadsheet by Ankur

http://www.cheresour...n-spreadsheets/

 

Using the spreadsheet compressibility_factor_z_calc.xls should help you to solve your query. It should be noted that the 7.2m3 normally implies the volume when discharged to atmosphere, hence you will put in atmospheric pressure. As for the temperature, different companies use different standards and its mostly never stated. Perhaps you can try 15C or 25C or 70F if you come from those countries.

Don't get too caught up on getting the same number, as you have no idea which EOS the company used to calculate it as well as the conditions it is referring to anyway, so your answer would very likely be different.

Also, the cylinder you have that has methane, what it means is that the gas pressure inside is 150bar and that when discharged, it will yield a volume of 8.9m3. It does not literally mean 8.9m3 @ 150bar as it states there....

Edited by thorium90, 12 August 2013 - 11:37 AM.