This is what we got in terms of hard numbers off our last experimental smelt - at the Haffenreffer Museum during the program ran for students at Brown University. (a description on an earlier posting)
The furnace was a standard 'Norse Short Shaft' and was built with a series of small holes down the back side of the cylinder. This put these holes at 90 degrees to the placement of the tuyere. So effectively these could measure the middle of the furnace.
The holes were placed every 10 cm, started from the top of the furnace down. This put the lowest hole at roughly tuyere level.
Measurements were made using a digital pyrometer. The thermocouple wire was inserted into each hole in turn.
Only three sets of readings were possible. There was an equipment failure, caused by the student who installed a fresh battery not correctly closing the case of the instrument. The first set of measurements was made at a point where the charcoal column had yet to fully ignite, so do not represent true working temperatures.
The other two sets of measurements are at roughly the point where there was a full ignition of the reduction column, and at a point 30 minutes after that. It should be noted that we were still establishing the correct balance of air flow against consumption rate (which is also in effect establishing the correct internal furnace temperatures). The ideal situation would be to produce a complete set of temperature readings over the whole progress of a working smelt.
The table was created by Ian Brownstein, who took the measurements on smelt day.
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