Enter FORGE-FROM-HELL V THE WRATH OF KHAN (VECTION).  There are water cooled tuyeres, there are air cooled tuyeres, there are tuyeres that just seem to work well without melting or eroding.  My goals were modest: a tuyere that requires no maintenance, a life of 50-60 years under hard use, a large air delivery capacity, no moving parts, no parts that can break, and can be constructed in 1 hour for less than $6.  Fig. 1 illustrates what I came up with.  It occurred to me that  though I had been told that mild steel is more resistant to elevated temperatures than tool steels, I could easily work mild steels at very low temperatures, whereas, even at a bright yellow common alloys such as those used in heavy leaf springs are-well-as they have come to be known among the rather unstable group of smiths I regularly cavort with, as tough as "whale poop"(No, I have no idea from where this originates.  And no I haven't substituted any words here, my buddies are unstable not profane).  The idea then was to construct airway dividers which while having a maximum of air quench area (to benefit as much as possible from the incoming cool blast), while obstructing the airway as little as possible.  Two features are essential: First, the dividers are notched on both ends where welded to the 2" coupling to clear the air supply pipe when threaded into place, also providing additional quench area; and second, the dividers must be tapered toward the air supply to prevent waste material from obstructing the airway (fig.2).  Much to my dismay this design fulfills the aforementioned goals quite nicely (Though I'm not entirely sure about the 50-60 year lifetime thing-I'll have to get back to you).  After I had beveled the sides of the firebricks and snugly tapped them into position around the perimeter of the firepot to keep them in place, it seemed all my problems were behind me.....almost.

     I discovered at length that working in a small closed shop with a wailing vac motor was about as relaxing as listening to the local ladies club use a blackboard as a nail file, but louder.  Enter FORGE-FROM-HELL VI THE FINAL AFFRONT-EAR.  Since I had become accustomed to having a very high pressure blast on those few occasions when you need to have a working fire in 5 minutes, or are making a trivet out of a railroad track, I left the vac motor, but added a 100 cfm medium pressure blower on a second inlet to the main air supply line, also with an inlet-side restrictor valve.  This valve is really used to eliminate the small blower as an air leak while the vac motor is in operation, as I use the ash gate as an air dump to control the blast from the small blower.  Similarly, while the small blower is in operation, the inlet valve of the large blower is closed.  Granted this air control system is overly complicated to control, but then nothing grabs the attention of visitors like a plume of red-hot coke!

     It is well to point out that my forge needs are largely different than those of most smiths.  I may be making a rosebud embellished candlesnuffer one day, and bending the front axle of a semi tractor to form the backbone of a large pneumatic hammer the next.  In essence, I have no typical uses and my forge must be capable of maximum flexibility.