BTU FROM PERCENT METHANE 2

[DANTHEELECTRICMAN]

HELLO: I WAS HOPING A PROFESSIONAL IN THE FIELD COULD HELP WITH VERIFICATION. I DID GOOGLE AND FOUND A LOT OF HELPFUL INFORMATION,BUT THAT FINAL VERIFICATION WOULD REALLY HELP.I WANT TO KNOW HOW TO CALCULATE BTU OF METHANE FROM PERCENT BY VOLUME OF METHANE GAS. FOR EXAMPLE: I HAVE 10% METHANE(FROM METHANE DETECTOR ON A MUD LOGGING SITE), WHAT IS THE BTU...A FORMULA AND TO WORK THIS EXAMPLE WITH AN ANSWER WILL BE SUPER HELPFUL.THANK YOU...

 

[Latexman]

What's the other stuff in the gas?

Good luck,
Latexman

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[DANTHEELECTRICMAN]

HI: MOSTLY AIR,A SMALL TRACE OF CO2 USUALLY LESS THEN 1%...

 

[LittleInch]

BTU is a measure of energy. To calculate energy you need to know the mass of the gas or volume at standard conditions, not just percent. Also methane will only burn between about 5 to 15% in mixture with air.

As you've probably discovered, BTU/ scf of pure methane is about 1020BTU/scf. % methane is therefore irrelevant, it's total quantity (standard volume or mass) you need. So if you have one standard cubic foot of 10% methane in air, then you have energy in BTU, if you can burn it, of about 100 BTU. Unless you know standard volume or mass you can't calculate it.

Unless you've got virtually pure methane though, this could be quite different if you've got a mixture of methane, butane, propane and other gases commonly found when coming out of the ground.

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Also: There's usually a good reason why everyone does it that way

 

[DANTHEELECTRICMAN]

HI:OK SO I KIND OF GOT THE IDEA NOW...HOW DID YOU COME UP WITH 100 BTU WITH MY EXAMPLE??? Link THE ENCLOSED THREAD HAS THIS FORMULA...

 

[Latexman]

For youe gas, btu/cf = 10 x % methane.

For 100% methane, 10 x 100 = 1000 Btu/cf.

For 10% methane, 10 x 10 = 100 Btu/cf.

What are you planning to do with this gas? Pipe it somewhere and burn it? Just curious.

Good luck,
Latexman

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[DANTHEELECTRICMAN]

HI: I DESIGN ELECTRONIC CIRCUITS. SOME INSTRUMENTATION FOR MUD LOGGERS IN OIL AND GAS.USUALLY I BUY PRE MADE SENSORS AND BUILD CIRCUITS AROUND THEM..SO I WAS TALKING TO SOMEONE,THEY SAID THEY USE A HANDHELD SENSOR THAT MEASURES PERCENTAGE OF METHANE,FROM THE GROUND,CONVERTS IT TO BTU. THEY DO SAY IT IS NOT AT ALL PRECISE. THERE ASKING FOR BETTER PRECISION..SO THAT IS MY CONFUSION:THE PERCENT TO BTU IDEA...ANY IDEAS???

 

[LittleInch]

Hand held sensor measuring percent methane, no problem, plenty about.

Convert to BTU, impossible without measuring volume or mass.

Convert to BTU per scf of the air / methane mix, multiply percent by 10. Not incredibly accurate, but not far off.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[DANTHEELECTRICMAN]

WELL I HAVE LEARNED A LOT THROUGH THIS DISCUSSION.NOW I KNOW WHAT I NEED TO MAKE THE INSTRUMENT WORK RIGHT. MUCH THANKS FOR YOUR TIME AND EXPERTISE. I AM SURE I WILL BE BACK WITH OTHER GAS RELATED QUESTIONS...THANK YOU SO MUCH AGAIN...

 

[LittleInch]

Looking at this again, the other reason as said by others is that the gas they are measuring probably contains other gases apart from methane (although methane is probably the highest component) which can signficantly affect the BTU / scf calcualtion. If you liked the posts there is a button for that...

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way