[TheForge] hot portable atmospheric forges may need propylene

Tue May 31 20:10:12 EDT 2005

Right I was trying to say that the O2 is limited by the Hi % of Nitrogen in 
the air.
You are  also are heating and exhausting the nitrogen so you are loosing 
potential heat.
The Propylene sounds interesting.
I might try swapping a 11/4" "T-Rex" AB for my blown burner in my vertical 
pipe forge.
If the burner is located at least 10" below the billet door opening, it is 
way more efficient than a horizontal pipe forge.
Chuck

----- Original Message ----- 
From: <Keporter at aol.com>
To: <theforge at mailman.qth.net>
Cc: <skipjack394 at verizon.net>
Sent: Tuesday, May 31, 2005 5:46 PM
Subject: Re: [TheForge] hot portable atmospheric forges may need propylene

>
>
>
>
>
> Yes, atmospheric burners are self limiting, but no, they aren't  limited 
> by
> the amount of oxygen they can draw in (any of these designs can  be tuned 
> to an
> oxidizing flame). The limit is the amount of nitrogen--not  oxygen--found
> within the intake air. Nitrogen contributes nothing to  combustion, and is
> therefore a drag on the flame's energy density. This is  the sole reason 
> that
> oxy/fuel flames are hottest. However, the theoretical limit  of an 
> air/propane flame
> is listed as 3600 degrees, so you might not want to  dismiss them out of
> hand.
>
> Liquid oxygen costs money to use. Quite a bit more money than the cost of
> many fuels. If you want to take the temperature of an existing forge 
> higher
> than you can get by using the best of tube burners (correctly tuned), the 
> best
> IR coating (water separated ITC #100), and the best exhaust system 
> (larger
> openings with exterior baffles), then the next logical step is the use  of
> propylene fuel gas, rather than oxygen enrichment. Propylene will cost you 
> about 40
> percent more than small amounts of propane, but it is still only  about 60
> percent of the cost of MAPP gas; at least in Seattle.  Propylene was rated
> between 25 and 50 degrees of the temperature of MAPP.  However, Air 
> Liquide has
> replaced the propane content in its formula with  propylene, so this can 
> no
> longer hold true. In fact, I'll have to write them now  and find out what 
> the new
> flame temperature of MAPP is supposed to be.
>
> I have done a study of oxygen enrichment, and it works great as an
> economical means of raising natural gas flame temperatures.  With twenty 
> percent
> enrichment, you receive about a 1000 degree boost.  That's an excellent 
> investment,
> when you factor in the low cost of NG. The  reason enrichment works so 
> well is
> two fold: First, you get the biggest  temperature increase for oxygen
> enrichment at the lower end of a sliding scale;  the upper end of that 
> scale shows
> only a 50 degree increase for the final  twenty percent oxygen invested.
> Secondly, the fuel it's commonly used  with (natural gas) requires the 
> least amount
> of added oxygen (1.5 to  1) of any fuel but acetylene (1.1 or 1.2 to 1
> depending on whose  figures you use). Using it with propane, you would 
> need 3.5 to 1
> of added  oxygen. Therefore, you can multiply the needed percent of added
> oxygen by the  difference between these figures; at this point switching 
> to
> propylene is  not only looking simpler, but cheaper too. Propylene uses 
> the same
> fittings and  regulators as propane. I have used it during burner tests, 
> and it
> will give the  same comparative heat increase over propane with top flight
> burners or  ancient designs. On the other hand, my interest in propylene 
> is for
> hand torches  and burners being used as hand torches, where ambient air 
> can help
> cool  the SS nozzle. When you start running internal forge temperatures up 
> to
> the  higher ranges for very long, you well most certainly melt the SS 
> nozzles
> right  off your burners, so you want to use a good grade of ceramic to 
> build
> a burner port, with the nozzle shape incorporated,  instead.
>
> I have not bothered with recuperative schemes, because the temperature 
> boost
> simply isn't worth the added building expense and lack of design
> flexibility, for ordinary forge work. Since, these higher temperatures are 
> needed for
> some projects, one of you might give them a second look.  There is the 
> Sandia
> forge with plans already existing, but I think an all  ceramic version 
> would be
> the best design. It would probably also work best  with the ceramic 
> nozzles
> everyone will need to operate at the desired  temperatures. However, it 
> will
> either need a tall stack or fan to suck hot air  down into the furnace, 
> and
> neither scheme sounds very compatible with the word  portable. In the 
> meantime
> propylene out on a demonstration site is a very  minor cost compared to 
> say a
> hot-work permit, or even just your  time and travel expenses :-)
> Mike P.
>
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