Standard cubic meter natural gas consumption calculation

[yirmidokuz]

Hi all,

I am trying to calculate of our natural gas consumption per tonnes of aluminum that they be casted in our furnaces.

I checked the natural gas meter for one month and divide the result by the amount of aluminum that casted.

The result is 115m[sup]3[/sup]/ton. But to make sense out of this data ıt should be converted into standard or normal cubic meter.

Our gas pressure at the exit of the valve is 0.2 bar and the temperature is about 20°C.

I use the formulae

Vsm[sup]3[/sup] = Vm[sup]3[/sup] * (P_working/P_absolute) * T_abs/T_work * (Z_sm3/Z_work)

I take the Z compression factor ratio as 1.

Hence,

V_sm3 = 115 * 0.2/1 * 288/303 * 1
V_sm3 = 21.8 sm3/ton

which is not a plausible value. Where do i make the mistake ?

 

[EdStainless]

My guess is that the meter does not read m3.
Most read in some random units, and on the meter face in very small print it gives the conversion factor. The meter should be compensating for standard conditions.

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P.E. Metallurgy, Plymouth Tube

 

[dgallup]

I'm sure your gas pressure is 0.2 bar GAUGE, not absolute so you need to use 1.2/1 in your equation. That is the big error.

Your temperatures don't look right either. 20C is 293K which is SOMETIMES the standard temperature. Unfortunately, there is no absolute standard STP, many different "standard" conditions.

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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

 

[yirmidokuz]

@EdStainless

That could be right. But how can i check that if the meter reads m[sup]3[/sup] or sm[sup]3[/sup].
It writes m[sup]3[/sup] in the unit of the indicator.

@dgallup

How did you come up with 1.2/1 ? I couldn't get it exactly.

 

[EdStainless]

Have you looked on your gas bill?
Though it may be in therms, mine lists both volume and heating value.

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P.E. Metallurgy, Plymouth Tube

 

[yirmidokuz]

@EdStainless

Nope, I hadn't checked it. I will. Thanks.

 

[dgallup]

"How did you come up with 1.2/1 ? I couldn't get it exactly."

Because your 0.2 bar pressure measurement is a relative pressure, not an absolute pressure. So you have to add atmospheric pressure to it (1 bar roughly).

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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

 

[yirmidokuz]

@dgallup

I see, thank you for the explanation.