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Q?: water vapor by volume in natural gas

SperrySperry Member Posts: 5,006 ✭✭✭
edited August 2006 in General Discussion
This topic came up in sales training.
90+ heaters, condensing heaters, put out alot of water as condensate.
Does anyone know the amount [per 1000 CF, maybe, at average municipal delivery pressure?]

is there a way to say "A 100K BTU furnace running constantly will put out "X" amount of water as a liquid, and the other 10 % as vapor"?

Thanks.

Comments

  • SperrySperry Member Posts: 5,006 ✭✭✭
    edited November -1
  • bpostbpost Member Posts: 32,664 ✭✭✭✭
    edited November -1
    My furnace is 94% efficient, It does produce a lot of water when running. I think more water comes from the humidity in the combustion air than is in the gas supply. Water vapor in gas supplies is controlled by the drip line and by the use of methanol in the storage tanks.
  • nordnord Member Posts: 6,106
    edited November -1
    Gas is delivered dry for all intents and purposes. Water and water vapor are a product of combustion. Thus, complete combustion of a hydrocarbon will produce CO2 & H2O. H2O being either condensate or gas. CO2 being a gas.

    The volume of the end products will depend on the exact makeup of the fuel in question. Not being a chemist I can only surmise that the exact chemistry of natural gas may be slightly different in different areas. BTU's will vary as will the end products of burning the gas.

    I'll say with some certainty that an accurate estimate is much more than possible. We can determine the weight of the gas being used and it's no secret that O2 combines to form the products of combustion. Perhaps a bit of math and a consult with the Periodic Table would be in order. That and a willing chemist and you'll have the answer.

    Or... Burn a known quantity of gas and see how much water is produced. In a 95% efficient furnace there should be only 5% H2O leaving as a gas. Math is pretty simple there.
  • texaswildmantexaswildman Member Posts: 2,215 ✭✭
    edited November -1
    From the field, most natural gas is not delivered above about 6% moisture. Pipeline companies can't handle the "liquid" in transport lines - and actually your household systems can't either. The end-line gas delivery companies dry it as much as they can and still sell it. The more liquids in the line, the more freezing that occurs as the product goes through the pressure drops to sales points - and freezing ain't good. Methanol is injected to help prevent this freezing. You can pull dragger tubes to determine the amount of moisture in the gas.
  • MIKE WISKEYMIKE WISKEY Member, Moderator Posts: 9,961 ******
    edited November -1
    THIS WOULD DEPEND A. ON THE AFUE OF THE FURNACE, B. THE TEMP. RISE THROUGH THE FURNACE AND C. THE FIRING RATE (IN YOUR EXAMPLE 100,000 BTU'S/HR.) ALSO THE INPUT AIR TEMP. WOULD BE A FACTOR (THE COLDER THE INCOMING RETURN AIR THE MORE CONDENSATION).
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