Since the Chinese box bellows (windbox) has now been brought into the
discussion, I should mention that some tests of this type of blowing
engine were made in 1958, in connection with the Great Leap Forward,
and are reported in my book, _Dabieshan_ (London: Curzon Press,
1985, pp. 54-7). In the test the windbox was operated by 4 teams of 6
persons each, changing every 1-2 minutes. Stroke rate varied between
55 and 66 strokes/min. Pressure varied between 280-300 mbar, at the
end of the forward stroke, and 20-40 mbar at the end of the backward
stroke. Average air output was 9 m3/min.
This was in a special test (called a 'sputnik launch') to see how far
production could be pushed in a small 'dwarf' blast furnace, ca. 2 m
high, smelting ironsand with charcoal. When the experimenters
substituted an electric blower (pressure only 100-120 mbar) for the
windbox they had great trouble with 'flying sand'; apparently the
pressure variation was important, just as Tom Chase reports for the
tatara furnace.
Don Wagner
>The question of continuous versus intermittent draft has also come up in
>reconstructions of the Tatara iron smelting process in Japan. The initial
>experiments to revise the process (in the late 1960s?) were done with
>centrifugal blowers. They were easier on the operators than the traditional
>Tatara bellows, which two men stomped on with their feet while hanging onto
>ropes from the frame.
>
>Apparently, continuous draft was not as good. Now the reconstructed Tatara
>furnace in Shimane Prefecture (supported by Hitachi, I believe) has a pair of
>BIG Chinese box bellows run by eccentric cranks and piston rods off a large
>(7 horsepower?) electric motor with a speed control. They pump at about the
>breathing rate of a person and one can see the flames of the furnace wax and
>wane with the pumping. I was fortunate to be invited by Ryu Murakami of the
>Nara National Research Institute for Cultural property to visit the Tatara
>Furnace last February, and we saw the end of the process -- where the furnace
>wall is pulled down and the bloom is revealed.
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dr.phil. Donald B. Wagner
Reverdilsgade 3, 1.th.
DK-1701 Copenhagen V
Denmark
http://staff.hum.ku.dk/dbwagner
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