Gas Heat Value BTU/SCF & KJ/BTU?

1 BTU = 880 SCF?
1KJ = 1.055056 BTU?
Please make a correct these.
Thanks & regards,

[JohnS]

Originally Posted by Unregistered

1 BTU = 880 SCF?
1KJ = 1.055056 BTU?
Please make a correct these.
Thanks & regards,

The second figure is correct, mostly. The kJ is a precise measure of energy; the BTU is not. The BTU is the heat to warm 1 lb of water 1 degree F. Unfortunately, the heat capacity of water is not a constant. There are at least five "flavors" of BTU, depending on the starting and final values of water temp. The values are fairly close together and the figure you cite is one of the commonly used. It is generally denoted by an IT subscript on the BTU from International Yables (of Steam Properties).

The first figure is wrong. For pure methane, it might be reversed, 1 SCF = 880 BTU. But it is different for every gas or gas mixture. Most natural gas, while largely methane, has a fair percentage of ethane, mayvbe a little propane and other gases. It varies by source but 950-1050 BTU/SCF is more common. Then there is the whole issue of HHV and LHV. HHV is higher and assumes the combustion products are cooled to the initial temperature including condensation of exhaust water vapor to liquid water. LHV assumes the water remains as vapor and the difference is the heat of vaporization.

Thank you. I was just in need of the same info and lo! it appeared.

Bill

I'm trying to figure out which is most ecomonical to heat with nature gas of propane gas. I'm putting in a boiler to heat an in floor hydronic system. There is a natural gas line 2000 feet away with a $5,000 tap charge.

John C.

[JohnS]

Originally Posted by Unregistered

I'm trying to figure out which is most ecomonical to heat with nature gas of propane gas. I'm putting in a boiler to heat an in floor hydronic system. There is a natural gas line 2000 feet away with a $5,000 tap charge.

John C.

Natural gas is almost certainly cheaper; the question is whether it will be enough cheaper to pay off the $5000 tie-in charge in a reasonable time.

The gases can be measured in a confusing variety of units, so you may need some conversions. You need to know the heat rating of your boiler and how much it will run. Even in winter it probably won't run continuously, the thermostat will cycle it on and off. But you need to estimate the total number of BTUs you will use per year.

The gases may be priced by the cubic foot, but you need to know the heat content. Heat content varies slightly by source, or by quantitative anylsis of the gas, but natural gas runs around 1000 BTU/ft³, propane around 2500 BTU/ft³ (propane may be priced as a pressurized liquid rather than a gas). You need to consider both price and heat content of the gas to work out a price per BTU.

hello every body
i wonna convert from BTU/lb to BTU/scf
can u help me