Hello,
Similar to Tim Young I have been away from the machine for a few days. As
Tim and Henry Cleere, David Killick and others have done I would like to
weigh in on the present issues relating to Skip William's experiments. I
feel that many of the initial comments were mean sprited and narrow minded.
To complain that an experiment is lab based rather than replica based and
therefore invalid misses the point of research entirely. As an
experimenter who has done both I happily will say that I find replica based
more interesting for my own pursuits, however there is certainly more than
a role for lab based. And in all cases there is a crying need for more
experimentation and the discussion of the results.
With that is mind, bellows and blowers. We at Smelt have largely
abandoned bellows for the tall shaft experiments - chimmney effect draft is
more than sufficient. With mid-shaft experiments bellows are necessary,
intermitently. We have found that with a 40 cm diameter furnace with a
shaft height of 1.4 meters (a design originally largely borrowed from Henry
Cleere's mid-shaft work) that bellows are not necessary for a preheat if
charcoal of sufficently large diameter is used so as to not clog the air
spaces (this emphasis was largely borrowed from Peter Crew. However, once
the ore charge is added along with more char bellows are needed, both
because the ore, and shortly slag and bloom, clog the furnace sufficiently
to require a bigger push fo rthe blast and also because the plusating
nature of the bellows blast helps to encourage the burden to settle. It is
interesting to note that when we run a tall shaft furnace with just
convective draft vigerous and frequent rodding is required from above to
accomplish the same burden movement. Following the above methods for a
mid-shaft furnace we consistently produce blooms and gromps weighing 12 -
14 kg in a day's batch smelt.
As a final note about our bellows experience, sparked not doubt that it is
rainy and 57 outside, the blast rates have to be vary variable throughout a
single cycle and especially from cycle to cycle. Humidity is the single
biggest factor, I would not try to run a low or mid-shaft furnace on a day
such as today - 100% humidity. Everything else, temperature, wind speed,
etc we have found to be unimportant for the furnace, if not the crew.
Carl Blair
Director of SMELT
Dept of Social Sciences
MTU
Houghton MI 49931
USA
[log in to unmask]
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|