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kevin, what you said is exactly right. A SLIGHT positive pressure is a good thing, just don't stand next to the drop out door if it goes VERY positive! The dragon's breath from a 150 ton per hour re-heat furnace can ruin your whole day. :(

 

Tai.....uh.....I guess not. :blink:

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Just get that puppy up to a white heat and suck a bucket of water into it. :D

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Well Tai I have compared the scale on that no-hardening SOB lawnmower blade and a piece of 1095 and I now know exactly what you mean. The scale on the 1095 just flakes right off but on the LM blade it "sticks" to it. I think the motto for bladesmithing should be "live and learn".

 

Loren

 

-Note to self: don't use lawnmower blades!

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Well Tai I have compared the scale on that no-hardening SOB lawnmower blade  and a piece of 1095 and I now know exactly what you mean. The scale on the 1095 just flakes right off but on the LM blade it "sticks" to it. I think the motto for bladesmithing should be "live and learn".

 

Loren

 

-Note to self: don't use lawnmower blades!

24390[/snapback]

 

Right on!

Keep a close watch on that scale. :)

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Now we're talking "Fire Scale Behavior 101" ! ;)

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Guest Perkins
A high velocity burner, blown type, can get the atmosphere in the forge to rolling and create eddies at the edges that can suck in air from the edges of the portals.  The atmospheric burners are based upon the venturi effect to suck in air for combustion.  Now, methan burns hottest at about a 10:1 ratio of air to gas.  If you are running excess air, you get more scale.  If you run excess gas, you get carbon monoxide.  :(

 

Certain methods used to make steel will affect scaling, too.  For instance, a silicon killed steel will hold scale more than a silicon-aluminum killed steel.  High chromium steels will scale less because the chromium retards the formation of iron oxide.

 

I will try your suggestion to put a charcoal brickette in the forge to minimize scale. I does make some perverse sense that if you can vaporize some carbon, it will scavenge the oxygen and make CO2 or, CO (  :blink: ) instead of FeO.

24066[/snapback]

 

 

Sorry to bring back an earlier statement, but I just started reading this thread, and I'm confused.

 

You're saying that an excess of air creates FeO, and an excess of methane creates CO2, right?

 

(Though the compound is actually Fe2O3, for the sake of simplicity, we can leave it all unbalanced)

 

CH4 + O2 + Fe --> CO2 + H2O + FeO

 

Since the reactants are CH4, O2, and Fe, increasing any of them should increase Carbon Dioxide and Scale outputs equally. I don't understand why increasing methane or oxygen would have an impact on this: the iron is clearly the limiting reactant.

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Perkins, Step out of the chem lab and into the real world. Industrial furnaces often do not run on stoichiometric ratio (as your redox equation does). It takes just about 10 volumes of air to burn one volume of methane. If you have 12 volumes of air, there is more oxygen to create FeO, Fe2O3 or Fe3O4 as may be appropriate to the temperature. If you have 8 volumes of air to one of methane, some of the methane will not bet burned and the products of incomplete combustion usually include carbon monoxide. Most furnaces are run with at least 10% excess air to prevent an CO formation. ;)

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Don't forget that any attempt to determine ideal stoichiometry based upon a single chemistry gas such as methane is a classroom endeavor only. Natural gas companies sell based upon BTU's per 1000 cubic feet of product. Natural gas is always a blend of gases such as methane, ethane, propane, and other variants. Past practice was to add propane and adjust BTU content with nitrogen. Unless you know exactly what is going into a burner at that instant, you can't determine the ideal air to gas ratio.

 

One of the largest selling points for the industrial gas companies in converting commercial heat treaters to atmospheres using nitrogen and methanol was the constant chemistry they produced versus that obtained by endothermic gas generators which cracked natural gas over a nickel based catalyst to produce nitrogen/carbon monoxide/carbon dioxide atmospheres, and varied with the chemistry of the natural gas feedstock.

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You guys done lost me way back there. :D

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Ok - it wasn't my intent to add confusion to the universe. Is there any interest in reducing what I said to a lower level? I'll be out over the weekend, but will check the forum Sunday to see. If there is, I'll try to find time in the next week to write up a more basic explanation. Regards to all, Kevin.

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1. Fire Good.

2. Fire use air to burn.

3. If Fire not have enough air, fire make you sick.

4. If fire have too much air, fire make blade sick.

 

Ugh Ugh Ogah.............. :blink:

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1. Fire Good.

2. Fire use air to burn.

3. If Fire not have enough air, fire make you sick.

4. If fire have too much air, fire make blade sick.

 

Ugh Ugh Ogah.............. :blink:

24708[/snapback]

 

 

Hammer good too?

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