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March, 1925 forging- Stamping - Heat Treating 81
T h e D e v e l o p m e n t o f t h e R e c u p e r a t o r
Desire to Protect Our Natural Resources and the Importance of
Greater Fuel Economy Has Served to Stimulate Interest
TUT-ANKH-AMPLN, the famous Egyptian king,
lived in a remarkable age. The recently unearthed
relics prove this and serve as striking evidence
of the advanced state of civilization of a people living
3,000 years ago.—many centuries before the Dark
Ages. Their pottery, vases and innumerable goldembedded
objects, their works of art and their utilitarian
articles, demonstrate conclusively that the
Egyptians were highly skilled in the arts and sciences,
—that they were not ignorant of ceramics and metallurgy,
and apparently possessed a working knowledge
of practical methods for the application of heat.
Prehistoric Metallurgy.
Egyptologists, archaeologists, paleontologists and
other antiquitarians have taught us through their discoveries
that ages before the time of King "Tut" there
existed peoples with varying degrees of civilization.
As far back as 4,000 years before the era of
that powerful Pharaoh, human beings knew enough
about metallurgical processes to enable them to successfully
smelt copper and tin ores, and to fabricate
metallic implements. For even in the Bronze Age
did they know the value of fire, and how to harness
its energy for their own use. The practical application
of heat constitutes one of the oldest industries
known to mankind.
Early Furnace Development.
The methods employed for utilizing the heat of
the flame were always very simple and crude—in fact
it was only during comparatively recent times that
they have taken the form of what might be called
furnaces. The aim of those who built furnaces was
solely to produce sufficient heat to melt their metals
or to enable them to be worked into various forms
for manufacturing purposes. Only several decades
ago the success of an installation was measured entirely
by its ability to obtain the required temperatures.
The matter of fuel economy was relatively
unimportant then, as the state of our natural resources
and the extent of industrial competition did not warrant
efforts in that direction. The science of metallurgy
was not sufficiently advanced to require of a
furnace close temperature regulation.
Recent Developments.
It is merely a matter of recent years that it has
become necessary to direct any attention towards the
conservation of fuel and the production of certain
caloric effects demanded by our constantly increasing
knowledge of metallurgy, such as high flame temperatures,
elimination of oxidation, uniform furnace
temperature, etc. To accomplish these objects, engineering
research and inventive skill have devised
innumerable ingenious methods, such as oil burners
and atomizers, pulverized fuel systems, means for
producing radiant heat, electric heating units, gas
•Mechanical Engineer, New York, N. Y.
in Heat Recovery Through Recuperation
By E. R. POSNACK*
producers, stokers, insulating materials, refractories,
improvements in general furnace design, and systems
for the preheating of the combustion air, among many
others.
Each of these has its particular field of usefulness,
and has contributed its share towards the economical
and diversified utilization of fuels for industrial heating
purposes. However, there is unquestionably no
tine method that affords as many simultaneous advantages,
as to the requirements of both economy
and metallurgy, as the efficient preheating of air by
the utilization of the waste heat in the stack gases.
Heat Recovery.
A brief word of explanation about air preheating
and waste-heat salvage will be rather appropriate
here. To burn any kind of fuel, large quantities of
air are required. It has been generally recognized
that if this air could be raised to a high temperature
and injected into the furnace in this preheated state,
instead of cold, higher furnace temperatures would
be attained, thus widening and improving the field
of metallurgical operations. It is also a well-known
fact that of all the fuel used in a furnace, only a very
small fraction performs useful work, the remainder being
lost in various ways. By far the greatest part
of this loss is effected in the stack. In other words,
the smoke, or burnt gases, carry out and waste a
tremendous amount of fuel energy — considerably
more than is required to melt or heat the product.
The joint and practical application of these two established
facts—the establishment of a method of
diverting this potentially useful heat from a waste
channel to a production source— is the essence of the
term, "utilization of the waste heat in the stack gases
to preheat the air required for combustion".
The Regenerator.
About 70 years ago an engineer by the name of
William Siemens, realizing that the future industrial
world was to be built on a foundation of iron and
steel, bethought himself of the commercial possibilities
of an improved furnace system that would facilitate
the economical attainment of the comparatively
high temperatures required for the melting of iron.
His alluring dreams materialized into an ingenious
invention, the Regenerator, embodying a method of
reclaiming the waste heat in the stack to preheat the
combustion air. Today the name Siemens is synonomous
with iron, and inseparably connected with
steel. The development of the Siemens Regenerator
is considered one of the most notable events in the
history of industrial furnaces.
The regenerator now serves countless furnace installations
— not only the large open-hearth and the
gigantic reheating furnaces, but it is also an integral
part of innumerable glass melting installations. It
has progressed from the steel melting to the steel
working" industry, and expanded into the glass melting
field.