[TheForge] Re: preheating forge blower air

Tue Feb 5 16:37:00 2002

Stephen, are you the author of "Irony" ?  (I love that mag ) :) 

A lot of heat energy is wasted heating up the nitrogen in the air.  
Preheating would help a great deal with this.  Also,  while hotter air is 
less dense and therefore poorer in oxygen, it also has a less nitrogen.  
Recuperative gas forges benefit from this design and I dont see why a coal 
forge should be different. 

High performance automobile engines have to move air at extremely high 
speeds.  In this regime, air behaves differently from what we are used to in 
a coal forge with a blower. 

A recuperative forge should get to welding heat quicker and cheaper than the 
regular design but I dont see how it would heat the work any quicker.  The 
speed at which a given piece of steel heats up is determined by the temp of 
its surface and this in turn is limited by the temp at which the steel is 
damaged.  Since a non recuperative forge can burn  or melt most any steel, 
the heating time should be the same. 

Adam 

Stephen McGehee writes: 

> Frederick
> Yes, that has been thought about a lot.  In "plain and ornamental forging" by shwartzkof(sp?), he shows a cut of "The Lindwurm Recuperative Forge" and claims to be able to take 2" round to a forging heat in 2 min.  I attempted to do a patent search with what little info was in that book, but  the cumbersome search machine at the patent office web site and my own ineptness did not find anything.   With all the recuperative appliances the idea is that the hotter the combustion air, the hotter and more efficient the fuel conversion is.
> Dimitry Gerakaris uses hollow soapstone chambers around his flue to preheat frigid New Hampshire air for injection to his fire, not to get a hotter fire, but to keep 0 degree air from cooling the fire unnecessarily.  I want to build a recuperative firepot myself, have several pages of sketches already.  Please keep me in mind when you work yours up. 
> 
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