IMPROVEMENTS IN THE MEANS AND APPARATUS FOR RAISING HEAT BY THE COMBUSTION OF
Year: 1865

page_text: of Pennsylvania, United States of America, but now residing at Liver-
pool, in the County of Lancaster, for the Invention of "IMPROVEMENTS
IN THE MEANS AND APPARATUS FOR RAISING HEAT BY THE COMBUSTION OF
"
Sealed the 22nd May 1866, and dated the 25th November 1865.
PROVISIONAL. SPECIFICATION left by the said John Francis Bennett
at the Office of the. Commissioners of Patents, with his Petition, on the
25th November 1865.
I, JOHN FRANCIS BENNETT, of Pittsburgh, in the State of Pennslyvania,
United States of America, but now residing at Liverpool, in the County of
Lancaster, do hereby declare the nature of the said Invention for "IMPROVE
MENTS IN THE MEANS AND APPARATUS FOR RAISING HEAT BY THE COMBUSTION OF
FUELS OF VARIOUS KINDS," to be as follows:-
My Invention consists in producing any required degree of heat for the
reducing of metallic oxides, and for other purposes in the arts and manufactures
where high temperatures are required, by introducing one or more blasts of
[Price 8d.]

page_text: oxygen or atmospheric air (either hot or cold) at such different points in the
furnace or other apparatus employed, as that a fresh supply of oxygen shall be
introduced at or a little beyond or above the point at which the gaseous
deutoxide (or acid gas) produced by the first supply of oxygen has been
reduced to the gaseous protoxide (or oxide gas) by the chemical combination
of one atom of the gaseous deutoxide with one atom of the element used as
fuel, so that by a series or succession of combustions heat is continually added
to that produced by the first combustion, and thus a most intense heat is
produced, the degree of which is only limited by the capability of the furnace,
crucible, or other receptacle to withstand the same.
The mode of practically employing my Invention may be variously modified
according to the nature of the substance to be acted upon and of the fuel
employed, thus, for instance, in applying the same to a blast furnace of ordinary
construction for reducing iron ore, I apply at the hearth a series of inyeres,
through which a blast of hot or cold air is admitted as usual; at a height of, say,
six feet above these tuyeres I apply a second series thereof, and at a further
height of, say, six feet I apply a third series, and so on, when the operation of
smelting will take place as follows:-The furnace being fired on the hearth
as usual at starting, the oxygen of the atmospheric air entering through the
lowest tuyeres will combine with the charcoal or carbon of the material serving
as fuel in the furnace, producing, first, carbonic oxide gas at, say, 2,700°
Fahrenheit by the combination of one atom of oxygen only, and then, by the
addition of another atom of oxygen to the carbonic oxide gas, carbonic acid
gas is produced evolving a heat of, say, 5,400° Fahrenheit; the carbonic
acid gas of 5,400° Fahrenheit then, acts upon the iron ore and reduces it to a
fluid metallic state, and also acts upon another atom of carbon of the fuel,
and is thereby reduced to carbonic oxide gas. At a more elevated point of
the furnace, say six feet higher up, the blast from the second series of tuyeres
enters, and the upper stratum of carbon, heated by the carbonic oxide to, say,
2,700° Fahrenheit, combines with one atom of the oxygen thereof, producing
carbonic oxide gas of, say, 5,400° Fahrenheit, and then immediately combines
with another atom of oxygen and also with the carbonic oxide gas previously
produced, the result of which is the formation of carbonic acid gas at, say,
8,100° Fahrenheit; this acts upon the ore, reducing it to a fluid metallic state,
and again takes up another atom of carbon producing carbonic oxide.
process is repeated, and a consequent increase of heat obtained as often as
there are series of tuyeres in the furnace, which increase of heat is only
limited, as before stated, by the capability of the furnace to withstand the
This

page_text: same. As by the before-described arrangement the greatest accumulated heat
would be at the top of the furnace, I prefer in working blast furnaces according
to my Invention to fire the furnace from the top, and to cause the draught of
the furnace to travel in a downward direction, so as to produce the greatest
heat at the hearth. In applying my Invention to reverberatory furnaces the
same system as before described is employed, the current of the gas taking
place in a horizontal direction, and the gases resulting from the several com-
bustions produced by the introduction of air at points of the furnace that are
the required distances apart accumulate heat as before described, and are
made to act upon the ore or other substance placed upon a bed at the end of
such furnace.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said John Francis Bennett in the Great Seal Patent Office on the
25th May 1866.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN FRANCIS
BENNETT, of Pittsburgh, in the State of Pennslyvania, United States of
America, but now residing at Liverpool, in the County of Lancaster, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-fifth day of November, in the year of our
Lord One thousand eight hundred and sixty-five, in the twenty-ninth year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said John Francis Bennett, Her special licence that I, the said John
Francis Bennett, my executors, administrators, and assigns, or such others
as I, the said John Francis Bennett, my executors, administrators, and assigns,
should at any time agree with, and no others, from time to time and at all
times thereafter during the term therein expressed, should and lawfully
might make, use, exercise, and vend, within the United Kingdom of Great
Britain and Ireland, the Channel Islands, and Isle of Man, an Invention for
"IMPROVEMENTS IN THE MEANS AND APPARATUS FOR RAISING HEAT BY THE COM-
BUSTION OF FUELS OF VARIOUS KINDS," upon the condition (amongst others) that
I, the said John Francis Bennett, my executors or administrators, by an
instrument in writing under my, or their, or one of their hands and seals, should
particularly describe and ascertain the nature of the said Invention, and in
what manner the same was to be performed, and cause the same to be filed

page_text: in the Great Seal Patent Office within six calendar months next and
immediately after the date of the said Letters Patent.
NOW KNOW YE, that the said John Francis Bennett, do hereby declare
the nature of the said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement thereof, reference being had to the accompanying Drawing, and to
the figures and letters marked thereon, that is to say:-
The principle I have discovered is applicable to various purposes in the
arts and manufactures, and is calculated to produce an entire revolution in
the construction and plan of operation of furnaces of all descriptions; and
in order to enable others skilled in the various arts and manufactures to use
my said Invention in its practical application thereto, I will proceed to describe
and illustrate my Invention as adapted to the generation of heat in a blast
furnace, and in so doing shall show its application to the present form of blast
furnaces, although, as I believe and shall after explain more fully, a change
might be advantageously made in the construction of the blast furnace which
would better adapt it to the manufacture of iron, and enable it to be made
direct from the ore in a condition for casting, moulding, or rolling without
the intermediate processes of puddling and boiling.
Before describing particularly the practical application of my Invention (by
way of example) to a blast furnace, I will state briefly the principles of natural
science on which it depends. Most of the known elements are metals, and
are capable of combustion when entering into combination with oxygen, the
degree of heat evolved depending upon the atomic proportions or quantity of
oxygen with which they are respectively combined; for example, the metal
manganese exists in six states or conditions, namely, deutoxide, protoxide, the
metal cold (which are solids), the metal boiling (fluid), and protacid and
deutacid (which are gases). The process of combustion resulting from the
combination of metals with oxygen consists of distinct operations, which fact
forms the basis of my discovery, by the use of which any required degree of
heat may be attained, limited only by the capacity of the nietallic base for
heat and the capability of the material of the furnace in which the operation
is conducted to resist fusion. Thus, suppose the metal manganese cold or
solid at 0° Fahrenheit; to make it boiling a certain degree or amount of heat
must be added, which done another certain amount of heat must be added to
make this boiling fluid a protacid gas, and again another certain amount of
heat must be added to convert the protacid gas into a deutacid gas. These
various steps or stages of condition are attained by the access of successive

page_text: amounts or degrees of heat, which accession of heat is in each case to be
effected by causing atoms of oxygen to impinge upon the subject under treat-
ment in its various stages of deutoxide, protoxide, the cold metal, the boiling
metal, the protacid, and the deutacid successively, and the chemical combina-
sion with the oxygen effecting the required change of condition in each instance.
It is evident, however, that two atoms of oxygen could not be made to impinge
so violently on the solid or cold metal as to cause them to combine; the
metal must first be brought into a condition to receive the oxygen into com-
bination, which is done by heat artificially applied to raise the metal to a
boiling point, when the oxygen gas finding the metal becoming vapor can
impinge upon it so violently as to cause it to combine with the evolution of
one stage of heat, but even thus the two atoms of oxygen cannot simulta-
neously and together combine with the rising metallic vapor, but first one atom
of oxygen combines with one atom of the metal forming the protacid of the
metal, a distinct body, as separate and different from all other conditions of
the metal as the oxide of the metal is from its basc, or from its vapor, or from
its deutacid; if, however, we cause another atom of oxygen to be impinged
upon the atom of protacid gas (as it is nascent and before it has lost the heat
which it has evolved), this second atom of oxygen gas combines with the
protacid and forms the deutacid gas with the evolution of one additional stage
of heat. Thus then we have illustrated three stages of heat, namely.-
First, from the metal solid and cold at, say, 0° Fahrenheit up to the metal
boiling and becoming vapor.
Second, from the metal as a vapor to its combination with one atom of
oxygen and becoming protacid gas.
Third, from the protacid gas and its combination with one atom of oxygen
and becoming deutacid gas.
Each change producing an additional stage of heat. and here, at the third
stage, the height of the heat that can be possibly attained terminates, because
the deutacid gas is not capable of combining with another atom of oxygen.
but has reached its highest stage of oxidation. Each of these stages of heat
is 2,700° Fahrenheit; the metal being at 0° Fahrenheit becomes vapor at
2,700° Fahrenheit, the vapor becomes protacid gas at 2,700° Fahrenheit
plus 2,700° Fahrenheit, or 5,400° Fahrenheit above the metal at 0° Fahren-
heit, and the protacid gas becomes deutacid gas at 2,700° Fahrenheit more,
or 8,100° above the metal at 0° Fahrenheit, and this degree of heat (8,100°
Fahrenheit), as before stated, is the highest heat which this atom of metal is
capable of evolving, because it is incapable of receiving any more oxygen.

page_text: But the elevation thus attained forms a stepping stone for the attainment of
still higher degrees of heat, for commencing again with the deutacid gas at
8,100° Fahrenheit, and causing it to pass through or impinge upon particles
of hot solid metal (its own metal) heated to the same degree as itself, we
thereby deoxidize the deutacid gas one stage, reducing it to protacid gas of
8,100° Fahrenheit, and then cause to be impinged upon it another atom of
oxygen, when they will combine, forming again the deutacid gas, and evolving
an additional stage of 2,700° Fahrenheit heat, and giving a total result of
of 10,800° Fahrenheit, and so on ad infinitum in theory, but limited, as before
stated, to the capacity of the furnace or crucible to resist the degree of tem-
perature to which it is exposed.
I will now proceed to explain the mode of applying this general law to the
manufacture of iron in a blast furnace, referring to the accompanying
Drawing, in which Figure 1 represents an exterior view, and Figure 2 a
vertical section of a blast furnace of ordinary shape and general construction,
but so altered as to adapt it to my improvement.
In the Drawing a is a blast furnace; b, the hearth; c is a circular pipe
communicating the blast (either hot or cold) to the interior of the furnace
through the tuyere pipes e, e, e.
above the circular blast pipe c is
constructed to the lower blast pipe c, and from the upper pipe d a number of
tuyere pipes i, i, enter the chamber of the furnace. These blast pipes and
tuyere pipes may be repeated at regular intervals, so as to admit the blast into
the chamber of the furnace at different heights.
At a height of six feet more or less
another circular blast pipe d, similarly
The blast furnace a is charged with charcoal or coal and iron ore in the
usual way, and being lighted at the lower end above the hearth, and the blast
of air being introduced through the tuyere pipes e, e, and i, i, the operation is
as follows: Supposing the blast to be cold atmospheric air of the ordinary
temperature of 60° Fahrenheit, and the contents of the furnace before ignition
to have been at the same temperature, then, when the furnace is started, one
atom of the oxygen of the air blast acts upon the charcoal or carbon in the
furnace, producing carbonic oxide at, say, 2,700° Fahrenheit, then another
atom of oxygen enters into combination with the carbonic oxide, producing
carbonic acid, and evolving a heat of, say, 5,400° Fahrenheit; the carbonic
acid of 5,400° Fahrenheit then acts upon the iron ore and reduces it to a
metallic state, causing it to run down into the hearth of the furnace, and also
acts on another atom of carbon (of the fuel) at a more elevated point in the
furnace (say six feet higher up), and is thereby reduced in temperature by its

page_text: conversion into carbonic oxide of 2,700° Fahrenheit, but of double the volume
or quantity. At this point a blast of atmospheric air is introduced through
the upper tuyere pipes i, i. and the result is as follows:--The upper stratum
of carbon being heated by the carbonic oxide of 2.700° Fahrenheit combines
with one atom of the oxygen of the upper blast, and produces carbonic oxide
of 5,400° Fahrenheit, and then immediately combines with another atom of
oxygen, and the result is carbonic acid of 8.100° Fahrenheit. This carbonic
acid at 8,100° Fahrenheit then acts upon the iron ore, reducing it to a metallic
state, causing it to run down into the hearth of the furnace, and also acts
upon another atom of carbon (of the fuel), and is reduced thereby to carbonic
oxide at 5,400° Fahrenheit. If a third blast of cold air he now introduced at
another stage or stratum of the furnace (say 12 feet above the hearth) the
heat will be similarly increased still further. The carbonic oxide at that point
already raised to 5.400° Fahrenheit, having raised the carbon or charcoal
to the same degree of temperature, one atom of oxygen enters into com-
bination with the carbon at 5,400° Fahrenheit, and produces carbonic oxide
of 8,100° Fahrenheit, and then immediately combining with another atom of
oxygen produces carbonic acid of 10,800° Fahrenheit. This carbonic acid
then acts upon the iron ore and reduces it to metallic iron, which runs down
on to the hearth, while the carbonic acid, trebled in volume, combining with
one atom of carbon, is reduced to carbonic oxide of 8,100° Fahrenheit, and by
repeating the blast of air at a short distance still further up the heat may be
raised to 13,800° Fahrenheit, and so on ad libitum.
The figures given to represent the degrees of heat produced may not be
absolutely correct, but are given as approximations, and in practice the heat
could not be raised so rapidly, because some heat would be lost by the heating
of the impurities of the iron ore or other metal to be acted on by the heating
of the walls of the furnace and of the cold carbon, in order to bring it up one
stage of heat until it is capable of becoming carbonic oxide, and of the
carbonic oxide produced at the lower stages of the operation, and of the
nitrogen of the atmospheric blast: nevertheless the result attained, notwith-
standing the necessary amount of lost heat, would be a very rapid and
continually increasing elevation of temperature, susceptible of indefinite
augmentation within the limits of the capacity of the furnace to resist fusion.
In the application of my Invention to the description of furnace ordinarily
used where the fire is lighted at the bottom, it is obvious that the heat would
be greater in the upper than in the lower part of the furnace, and conse-
quently the iron produced in the lower part would mingle with that from the

page_text: upper part, which having been exposed to a much higher degree of heat
would be purer; I therefore prefer to light the furnace at the top, and
introduce the blast there first, and cause the draught to travel downwards, so
as to increase the heat downwards, in which case all the metal would pass
through the hottest part of the furnace.
In order that the principles on which my improvement is based may be
better understood I will give another illustration.
Let fire be lighted in an ordinary reverberatory furnace with coal as fuel;
if properly managed the total and highest heat raised will be 5.400° Fahren-
heit, and the product carbonic acid gas of two stages of heat or 5,400° Fahren-
heit. Now suppose the bed of the furnace to he unoccupied; let us build at
the end of it furthest from the fire a wall of loose coal, and by draught or
otherwise compel the carbonic acid gas to pass through this wall of coal until
the coal is raised to the same temperature (5,400° Fahrenheit), and then
continue to cause the hot carbonic acid to pass through this coal into another
chamber beyond it. The carbonic acid in passing through the wall of coal
becomes partially deoxidized, losing one atom of oxygen and becoming carbonic
oxide of 5,400° Fahrenheit, and in that state capable of combining with one
atom of oxygen, and thus evolving an additional stage of heat (2,700°
Fahrenheit), thus producing the result of carbonic acid of 8,100° Fahrenheit.
Let us now introduce into this second furnace bed (beyond the first wall of
coal) another atom of oxygen, and the result is carbonic acid of 8,100°
Fahrenheit, capable of being applied to the reduction of any metal or metallic
ore, or of being passed through another wall of coal and increased to the next
stage of heat, and so on ad libitum. Now let us suppose the crystalline Lake
Superior or Missouri iron (improperly called iron ore because it has evidently
been pure iron once, fused, and crystallized in cooling); it requires the same
degree of heat it lost in cooling to be again applied to fuse it; this degree
of heat is not known, but may be supposed not to exceed 5,000° Fahrenheit,
inasmuch as the combination of iron and carbon will melt as cast metal at
2,800° Fahrenheit, or thereabouts. Let this crystal metal be placed on the
first bed of the furnace just described, in which is present carbonic acid gas
of 5,400° Fahrenheit, and it would require a very long time to reduce it to a
melted state, but let it be put in the second furnace bed, and treat it to a bath
of carbonic acid gas of 8,100° Fahrenheit, and it will rapidly become fused.
In reducing a metal a bath of carbonic acid gas would be proper, and for an
ore or oxide of a metal carbonic oxide gas would be the proper bath. Suppose
we desire to reduce the ore alumina to its metallic state and produce

page_text: aluminium by my process, at present its melting point, state, or temperature
is not known, but suppose the ore alumina placed in a bed of the furnace
before described heated to the third stage or 8,100° Fahrenheit, and there
subjected to a bath of carbonic oxide of that temperature. If not reduced by
that treatment it would be removed to the next hotter furnace bed heated to
the fourth stage or 10,800° Fahrenheit, and there subjected to the action of
carbonic acid gas of that degree of heat, and so on until a bath of the requisite
ore into metallic
temperature was obtained which would convert the
aluminium. The same treatment with a like result would answer for the ores
of nickel and other metals. It is probable that no known metal would require
a higher degree of heat than this fourth stage, 10,800° Fahrenheit, to melt
it, and the metals at their respective boiling points would become fuels.
It will be understood that the blasts of air in all the various applications of
my Invention will have to be increased in volume at every stage in such
manner that if the first blast producing the lowest degree of heat be repre-
sented as one volume, then the next blast should be two volumes, the next
four volumes, and so on.
In the foregoing description of my improved process as applied to rever-
beratory furnaces, the introduction of separate beds at each of the several
points where an increase of heat is effected was only mentioned in order
more clearly to illustrate the nature of my Invention. In practice there
would be only one bed as usual at the point where the greatest heat would be
produced, and the several walls of fuel would be combined in one, as indicated
in the longitudinal section of a reverberatory furnace shown at Figure 3 of
the Drawing, where A is the furnace bed and B is the fire-place, which is of
such a length as to be capable of effecting as many increases of heat as may
be required by the introduction of a corresponding number of fresh blasts of
air at C, C. C2, C3, at the required distances apart. The fuel would for this
purpose have to be introduced at the top through apertures D, provided with
hoppers E, having a sliding cover at top and a sliding bottom, so as to keep
the fire-place filled with fuel right up to the arch of the furnace.
Figure 4 shows a longitudinal section of a Cornish steam boiler with my
A is the steam boiler, and B, B, B, three fire-
Invention applied thereto.
places filled with coal up to the bottom of the boiler, so as to cause the coal
to become a permeable wall. and C1, C2, C3, C', four blasts of air to be thrown
in as designated; the first blast C' to be of one volume; the second blast C2
to be of two volumes; the third blast C to be of four volumes; the fourth
blast C to be of eight volumes. The blast of air to be thrown in by draught

page_text: or bellows as may be found most practicable, with space enough between each
wall of coal to allow as much as possible of the heat generated to expend
itself in generating steam; and the value of the carbonic acid gas comparatively
hot being used over again instead of cold air, and the advantage of the
secondary operations of burning carbonic oxide instead of carbon may be
rendered thus say. 100 lbs. of carbon as commonly burnt, -
First, is 100 lbs. into carbonic oxide, and 2,700° heat evolved.
Second this oxide into carbonic acid and 2500° heat evolved.
value.
A similar arrangement of furnace is also applicable to glass furnaces, and
in fact to all manufacturing purposes where a high degree of heat is
required.
What I claim as my Invention, and desire to secure by Letters Patent, is
the mode herein-before described of producing any required degree of heat
for the reducing of metallic oxides or for other purposes in the arts where
high temperatures are required, by introducing two or more blasts of oxygen
or atmospheric air (either hot or cold) at such different points in the furnace
as that a fresh supply of oxygen shall be introduced at or a little beyond or
above the point at which the gaseous deutoxide or acid gas produced by the
first supply of oxygen has been reduced to the gaseous protoxide (or oxide
gas) by the chemical combination of one atom of the oxygen of the gaseous

page_text: deutoxide with the element used as fuel, and thus by a series or succession of
combustions continually adding to the heat produced by the first combustion,
substantially in the manner and for the purposes herein-before described.
In witness whereof, I, the said John Francis Bennett, have hereunto
set my hand and seal, this Second day of May, in the year of our Lord
One thousand eight hundred and sixty-six.
JOHN FRANCIS BENNETT. (L.S.)