Improvements in Means or Apparatus for use in Protecting Iron and Steel by Producing Magnetic Oxide thereupon.
Year: 1898

page_text: Date of Application, 11th July, 1898
Complete Specification Left, 10th Apr., 1899-Accepted, 17th June, 1899
Improvements in Means or Apparatus for use in Protecting Iron and
Steel by Producing Magnetic Oxide thereupon.
I, ANTHONY SPENCER BOWER, St. Neots, Hunts., Engineer, do hereby declare the
nature of this invention to be as follows:-
In the processes wherein iron or steel is oxidised by steam to produce magnetic
oxide thereon, it has been found to be of great advantage in so far as the tough-
ness and durability of the protective coating is concerned, to use a large volume of
steam at a higher temperature than that of the iron or steel under treatment, so
that the iron or steel is both heated and oxidised by the steam.
Only a minute portion of this steam is required to supply the oxygen to oxidise
the iron and steel, and the remainder has been heretofore been allowed to escape
from the oxidising chamber, and great waste of heat has resulted, including the
latent heat of evaporation, and that required to superheat the steam to a tem-
perature above that at which the iron and steel articles are maintained in the
oxidising chamber.
My invention has for one of its objects the reduction of the quantity of steam to
be supplied by a boiler, or other generating apparatus, whilst ensuring a large
flow of super-heated steam round, and among, the articles which are under treat-
ment.
According to this my invention, I provide a propelling jet of steam which sup-
plies the oxygen for producing the magnetic oxide on the iron or steel, and also
causes a large volume of steam, which may, or may not be mixed with other gases
or vapours, to circulate through the oxidising chamber the said circulating steam
or mixture being continuously drawn from, and after having been heated,
returned to the said chamber.
The steam, or mixture thereof, with other gases, may be heated by being caused
to pass through, or amongst, a system of pipes which have been previously heated
by products of combustion, or it may be continuously and uniformly heated by
being caused to pass outside or inside pipes, while products of combustion are
passing simultaneously on the inside or outside of the same pipes to keep up their
temperature.
Again, a mass or masses of brickwork may first be heated by products of com-
bustion, and the steam or mixture then caused to circulate through it, or them.
The mass, or masses, of brickwork may be heated in any convenient manner,
and is especially easy of application to the present Bower process where the iron
is first heated and oxidised by products of combustion which may also heat the
masses of brickwork. Some of the brickwork may be heated by the products of
combustion before they enter the oxidising chamber, and some of it by the said
products when they are leaving the chamber, and on their way to the chimney.
I do not confine myself to any of these plans, as the main point of my invention,
and for which I seek protection is, that instead of taking a large quantity of steam
from a boiler, or steam generating apparatus, superheating it, causing it to pass

page_text: over, and amongst, the iron or steel articles in the oxidising chamber,, and then
allowing it to go to waste, I now, by means of a jet propeller, actuated by a small
quantity of live steam from a boiler, draw the large quantity of steam, or a mixture
thereof, and which would have otherwise gone to waste, from the oxidising
chamber, force it through some kind of heater, and thence to the chamber again;
thereby inducing a constant rapid circulation of highly heated steam, or mixture
thereof with other gases, or vapours among the articles to be oxidised, while the
amount of live steam to be taken from the boiler may be exceedingly small as com-
pared with the amount of steam, or mixture thereof, with other gases, which has
hitherto been necessary to produce the required amount of circulation.
To use the live steam jet in the best manner for the purpose of circulation, I
may use an arrangement such as Korting's jet exhauster, or draught producer,
wherein sleeves of various increasing diameters are placed concentrically round
the axis of the jet. Since live steam is usually a necessity, this forms the best
method of producing a rapid circulation, but in order that the spirit of my inven-
tion may be clearly understood, I have to state that may, if I please, cause the
circulation to be produced by a fan, or spiral conveyor, in a manner well under-
stood. The steam when required, may then be supplied by an ordinary pipe to
some point of the course of circulation.
In the case of forced circulation by a jet, the quantity of live steam will depend
upon the rapidity of circulation required, as also upon the amount of oxygen
required to oxidise the iron or steel articles within the chamber, and which in
some cases has to be solely supplied by the live steam from the boiler.
A certain portion of fluid, similar in composition to that which circulates
through the chamber, must naturally be allowed to escape to the surroundings
since live steam from the boiler is continually entering the furnace. Part of
the oxygen of this steam is taken up, by the iron or steel articles, so that the
circulating medium may consist of steam mixed with a certain proportion of
hydrogen which has been produced by the decomposition of part of the said
steam.
Another part of my invention refers to cases where a very large surface of iron
or steel is required to be oxidised, and which is therefore ready to absorb a large
amount of oxygen, thereby causing the presence of a larger amount of hydrogen
in the circulating fluid than might be desirable, though at no time could that
circulating medium become neutral, or non-oxidising, so long as the propelling
jet, or other admission of steam, is in force, because either of these admissions of
live steam from the boiler would have to be itself rendered neutral, which could
only be done by the iron or steel taking up some of its oxygen, and this fact in
itself precludes the possibility of the circulating fluid being generally neutral.
In order, however, to reduce, or it may be, entirely destroy the presence of
hydrogen, I may allow the propelling jet, or other circulating apparatus, to draw in
a certain quantity of air, the oxygen of which combines with the hydrogen, and
reforms steam, so that the circulating medium may then be steam, nitrogen, and
hydrogen or steam and nitrogen only.
By this means a much more rapid oxidation of the iron or steel articles may be
effected than has hitherto been possible, for all the oxygen the iron or steel articles
require, can be readily supplied, and I may, if I please, admit so much air that
free oxygen may be present in the circulating medium which might then consist
of steam, oxygen and nitrogen.
Such a circulating medium might naturally produce a certain quantity of red 5
oxide (Fe) upon the surface of the iron or steel articles, but this may be
reduced to the magnetic oxide (Fe04) when ever desired, by cutting off the air
supply.
In the case of high temperatures, considerable free oxygen might be present
without producing the red oxide, as is instanced in the laboratory experiment of 5
burning iron in an atmosphere of oxygen.
In the case of cast iron, this plan has great advantages over the steam process.

page_text: pure and simple, as hitherto employed; for oxidation of cast iron which contains
a considerable amount of carbon, and which is only oxidised slowly by steam alone,
may be carried on rapidly with the mixture of steam and air, any appearance of the
red oxide upon the surface being reduced in a short period by cutting off the air
supply to the circulating apparatus.
Cast iron of a hard nature, and which has hitherto been found difficult to deal
with by steam alone, may be readily treated by my invention, for it combines the
rapidity of oxidation by products of combustion with free air amongst them, as
set forth by me in a previous invention, with oxidation by steam which produces
a more firm adherent, and flexible protective coating than do products of combus-
tion, pure and simple.
Again, rusty iron or steel articles may have the rust upon them reduced by
subjecting them to a circulating medium of steam combined with a large propor-
tion of deoxidising gases, or hydro-carbon vapours, and which may be drawn in
by the propelling jet or circulating apparatus in the same manner as was the air
hereinbefore mentioned.
Another part of my invention consists in utilizing the jet propeller, or other
circulating apparatus," to cool the iron or steel articles in the chamber before
drawing them out into the open air.
To do this, the jet propeller or circulating apparatus draws the hot circulating
medium from the chamber as before described, but in this case it is delivered
through a cooling, instead of a heating apparatus, which cooling apparatus may
consist of cooling passages, or a surface of water, or the hot medium may have
a jet of water injected into it in the form of spray, whereby it is rapidly cooled.
The then cooled medium is forced by the circulating apparatus to pass over the
hot articles in the oxidising chamber, picking up heat therefrom to be again taken
from it by the cooling apparatus, and so on continually, until the iron or steel
articles are deemed sufficiently cooled to be withdrawn.
This cooling process is akin to annealing and has the effect of preventing the
minute cracks in the coating of magnetic oxide of iron, and which are often visible
when highly heated articles are suddenly drawn out from the oxidising chamber
into the open air.
Also at the latter end of this stage of the process, a proportion of deoxidising
gases, or liquid hydro-carbon, may be drawn in by the circulating apparatus which
would still further improve the annealing action so that sheet iron similar to that
known as Russian may be the result.
T111.
T... 1000
E. EATON,
Agent for Applicant.
Improvements in Means or Apparatus for use in Protecting Iron and
Steel by Producing Magnetic Oxide thereupon.
ANTHONY SPENCER BOWER, Saint Neots, Hunts, Engineer, do hereby declare the
nature of this invention and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement:
My invention has for one of its objects the reduction of steam to be supplied by
a boiler or other generating apparatus whilst ensuring a large flow of superheated
steam round and among the articles which are to be coated with magnetic oxide.
According to this my invention I provide a propelling jet of steam which
supplies the oxygen for producing the magnetic oxide on the iron, or steel, and

page_text: also causes a large volume of steam which may, or may not be mixed with other
gases or vapours, to circulate through the oxidising chamber, the said circulating
steam or mixture being continuously drawn from, and after having been heated,
returned to the said chamber.
The steam, or mixture thereof with other gases, may be heated by being caused
to pass through, or amongst, a system of pipes which have been previously heated
by products of combustion, or it may be, continuously, and uniformly heated by
being caused to pass outside, or inside, pipes, while products of combustion are
passing simultaneously on the inside, or outside, of the same pipes to keep up
their temperature.
Again, a mass, or masses, of brickwork may first be heated by products of com-
bustion, and the steam or mixture then caused to circulate through it, or them.
The mass, or masses, of brickwork may be heated in any convenient manner, and
is especially easy of application to the present Bower process where the iron is first
heated, and oxidised, by products of combustion which may also heat the masses of
brickwork.
Some of the brickwork may be heated by the products of combustion before they
enter the oxidising chamber, and some of it by the said products when they are
leaving the chamber, & on their way to the chimney.
I do not confine myself to any of these plans, as the main point of my inven-
tion, & for which I seek protection is, that instead of taking a large quantity of
steam from a boiler, or steam generating apparatus, superheating it, and causing
it to pass over, or amongst, the iron or steel articles in the oxidising chamber,
& then allowing it to go to waste, I now by means of a jet propeller actuated by
a small quantity of live steam from a boiler, draw the large quantity of steam, or
a mixture thereof, & which would have otherwise gone to waste, from the oxidising
chamber, force it through some kind of heater, and thence to the chamber again,
thereby inducing a constant rapid circulation of highly superheated steam or
mixture thereof with other gases, or vapours, among the articles to be oxidised,
while the amount of live steam to be taken from the boilers may be exceedingly
small as compared with the amount of steam, or mixture thereof with other gases,
which has hitherto been necessary to produce the required amount of circulation.
To use the live steam jet in the best manner for the purpose of circulation I may
use an arrangement such as Körting's jet exhauster, or draught producer, wherein
sleeves of various diameters are placed concentrically round the axis of the jet-
Since live steam is usually a necessity, this forms the best method of pro-
ducing a rapid circulation, but in order that the spirit of my invention may be
clearly understood, I have to state that I may, if I please, cause the circulation
to be produced by a fan or spiral conveyor in a manner well understood.
The steam, when required, may then be supplied by an ordinary pipe to some
point of the course of circulation. In the case of forced circulation by a jet, the
quantity of live steam will depend upon the rapidity of circulation required, as
also upon the amount of oxygen required to oxidise the iron or steel articles within
the chamber, & which in some cases has to be solely supplied by the live steam from
the boiler.
A certain portion of fluid, similar in composition to that which circulates through
the chamber must naturally be allowed to escape to the surroundings since live
steam from the boiler is continually entering the furnace. Part of the oxygen
of this steam is taken up by the iron or steel articles, so that the circulating medium
may consist of steam mixed with a certain proportion of hydrogen which has been
produced by the decomposition of part of the said steam."
Another part of my invention refers to cases where a very large surface of iron,
or steel, is required to be oxidised & which is therefore ready to absorb a large
amount of oxygen thereby causing the presence of a larger amount of hydrogen
in the circulating fluid than might be desirable though at no time could that
circulating medium become neutral, or non-oxidising, so long as the propelling
jet, or other admission of steam is in force, because either of these admissions of

page_text: live steam from the boiler would have to be itself rendered neutral, which could
only be done by the iron, or steel, taking up some of its oxygen, & this fact in
itself precludes the possibility of the circulating fluid being generally neutral.
In order however, to reduce, or it may be, entirely destroy, the presence of
hydrogen, I may allow the propelling jet, or other circulating apparatus to draw
in a certain quantity of air, the oxygen of which combines with the hydrogen, &
reforms steam, so that the circulating medium may then be steam, nitrogen, &
hydrogen; or steam & nitrogen only."
By this means a much more rapid oxidation of the iron, & steel articles may be
effected than has hitherto been possible,, for, all the oxygen the iron, & steel,
articles require can be readily supplied, & I may, if I please, admit so much air
that free oxygen may be present in the circulating medium, which might then con-
sist of steam, oxygen & nitrogen.
Such a circulating medium might naturally produce a certain quantity of red
oxide (FeO), upon the surface of the iron, or steel, articles but this may be
reduced to the magnetic oxide (Fe,O), whenever desired by cutting off the air
supply. In the case of high temperatures considerable free oxygen might be
present without producing the red oxide, as is instanced in the laboratory experi-
ment of burning iron in an atmosphere of oxygen. In the case of cast iron this
plan has great advantages over the steam process, pure & simple, as hitherto
employed, for oxidation of cast iron which contains a considerable amount of
carbon, & which is only oxidised slowly by steam alone, may be carried on rapidly
with the mixture of steam & air, any appearance of the red oxide on the surface
being reduced in a short period by cutting off the air supply to the circulating
apparatus.
Cast iron of a hard nature, & which has hitherto been found difficult to deal
with by steam alone, may be readily treated by my invention for it combines the
rapidity of oxidation by products of combustion with free air amongst them, as
set forth by me in a previous invention; No. 1280,-A.D). 1878 with oxidation by
steam which produces a more firm, adherent & flexible protective coating than
do products of combustion, pure & simple.
Again, rusty iron, or steel, articles may have the rust upon them reduced by
subjecting them to a circulating medium of steam combined with a large propor-
tion of deoxidising gases, or hydrocarbon vapours, & which may be drawn in by
the propelling jet, or circulating apparatus in the same way as was the air herein-
before mentioned.
Another part of my invention consists in utilising the jet propeller, or other
circulating apparatus, to cool the iron, or steel,, articles in the chamber before draw-
ing them out into the open air.
To do this the jet propeller, or circulating apparatus, draws the hot circulating
medium from the chamber as before described, but in this case it is delivered
through a cooling, instead of a heating, apparatus, which cooling apparatus may
consist of cooling passages or a surface of water, or the hot medium may have a
jet of water injected into it in the form of spray whereby it is rapidly cooled.
The then cooled medium is forced by the circulating apparatus to pass over the
hot articles in the oxidising chamber, picking up heat therefrom, to be again
taken from it by the cooling apparatus, & so on continually until the iron, or steel,
articles are deemed sufficiently cooled to be withdrawn.
This cooling process is akin to annealing, & has the effect of preventing the
minute cracks in the coating of magnetic oxide oxide of iron & which are often
visible when highly heated articles are suddenly drawn out from the oxidising
chamber into the open air.
Also, at the latter end of this stage of the process, a proportion of deoxidising
gases or liquid hydrocarbon, may be drawn in by the circulating apparatus which
would still further improve the annealing action so that sheet iron similar to that
known as "Russian" may be the result.
And in order that my invention may be fully understood, & readily carried

page_text: into effect I will proceed to describe the accompanying sheet of drawings, reference
being had to the figures, & letters marked thereon.
Fig. (1) is an elevation of the furnace with the front portion of the brick work
removed so that the interior arrangement of parts may be seen.
Fig. (2) is a part plan, & part section, of the propelling & circulating apparatus,
& which is also shown in elevation in Fig. (1).
On Fig. (1); (A) is the fire place to be employed when solid fuel is used.
The fire varies in depth according to requirements. With a deep fire, as shown
in the drawing, (A) is of the nature of a gas producer, with a thin fire the products
of combustion therefrom may be fully oxidised, or complete at the time they leave
the fire. With a thick fire they require to be completed by a secondary supply of
air above, or beyond, the fuel bed.
Such secondary air supply may be provided at any convenient point, or points,
such as those marked a 2, 3, 4, then locality determining where the point of
the final & more intense combustion, shall take place if a gas producer be
employed. If a thin fire be used these secondary air supplies are not necessary.
() is the hopper required to feed a thick fire with fuel, with a thin fire fuel may
be fed in the ordinary way just above the fire bars. (13) is the chamber in which
the articles to be treated are placed.
The products of combustion, complete or otherwise, from (A) pass through the
channel, or channels, (C); & thence to the chamber (D), in which may be placed
the series of heating pipes (C). After having passed over these pipes the products
of combustion pass away by means of the passage (E), either to a chimney directly,
or to a steam generating apparatus first, or if steam be otherwise obtainable the
waste gases at (E), may be utilised to heat air, such air being used either to burn
with the gas produced in (A), in the case of a thick fire, or the hot air may be
supplied underneath the fire bars when the fire is a thin one.
The chamber (B), is thus surrounded either by fuel in a state of incandescence,
or by products of combustion; & it would therefore be heated to a considerable
extent in this way alone irrespectively of the hot fluid which is continuously
circulating within while iron, or steel, articles are under treatment.
One method of effecting this circulation is as follows, reference being had now
to both figures in which similar parts are indicated by the same letters.
A steam pipe (d) with a suitably shaped nozzle surrounded, it may be, with
conoidal sleeves of increasing diameter (e), placed within a pipe (f), of con-
siderable diameter.
In this pipe are openings (g), through which fluid may be drawn by the action
of the steam jet exhauster from the chamber (B), the said fluid, of whatever nature
it may be, passing from the chamber (B), to the side longitudinal passages (F),
by way of perforations (h), in the floor of the chamber (B). From these longitu-
dinal passages the fluid passes through other perforations (k), in the vertical walls
which support the floor of the oxidising chamber (B), & it is then drawn in to the
pipe (f), by the action of the steam jet apparatus, & forced thereby to the back
of the chamber (B), & thence in a zig-zag fashion consecutively through the rows
of smaller pipes (c), placed within the chamber (D), the uppermost row of these
pipes delivering into another pipe (), of large diameter which enters the
chamber (13), and passes from the back to the front of (B), at its upper portion,
and is provided with various holes, or perforations, (m) which serve to distribute
the now highly heated fluid over the iron, or steel, articles to be treated within
the chamber (B).
The greater portion of this fluid, somewhat altered in condition, by reason of
the deoxidising influence of the articles in (B); then passes through the perfora-
tions (), to be seized again by the jet exhauster, & propeller, in the pipe (f), &
so forced again through the heating apparatus to the chamber (B), & so on con-
tinuously.
A certain portion of fluid, about equal in quantity to that supplied by the steam
jet in pipe (f), where such is used, is allowed to escape, either into the atmosphere

page_text: directly by, it may be, orifices in the lower portions of the doors which close the
front, & back of the chamber (B), or again, it may be, by orifices in the right hand
longitudinal passage (F), & so directly underneath the fire bars where it may
mingle with the air supply passing through the said fire bars, & thus is of value
when the fire is a thick one, and the escaping fluid is largely composed of highly
heated steam; for such steam becomes decomposed when passing through the
incandescent fuel, & enhances the heating value of the gas evolved by the gas pro-
ducer (A).
This is the ordinary course of procedure when iron, or steel, articles of fairly
tractable nature are being dealt with. If however such articles expose a very large
surface to be oxidised, as for instance in the case of sheet iron, or steel, such articles
will rapidly absorb, or take up, oxygen from the circulating steam which will
gradually become a circulating medium of steam, & hydrogen; & so have its
oxidising influence impaired, & this I rectify by causing the jet exhauster & pro-
peller to draw in, through holes (n), a certain amount of air which air may burn,
or combine, with any undue excess of hydrogen, and reduce it to the state of steam
again; the surplus nitrogen being continuously given off, or rejected to, the atmo-
sphere at any convenient point in the course of circulation, such as, for example,
by means of the perforations which may be made in the right hand wall of the
longitudinal side passage (F).
The auxiliary air supply through the holes (n), is also of service where iron of
a hard nature, & combined with a considerable quantity of carbon, is being dealt
with; for in such cases it is found that the circulating medium may, with advan-
tage, have free oxygen present without producing the red oxide of iron or, (FeO3)
upon the surface of the articles under treatment but even if such oxide be pro-
duced, it may be reduced to the state of magnetic oxide, or (Fe,04), by another
portion of my invention, & which also applies to the case where rusty articles are
first put into the chamber (B), to be treated; the said rust being merely a com-
bination of the red oxide with water, or a hydrated sesquioxide.
In carrying out this portion of my invention, I cause the jet exhauster to draw
in, by means of a pipe (p), combustible, or reducing, gas from the top of the gas
producer (A); or if a thin fire be used, & such gases are not combustible, or
reducing, in character I may cause the jet exhauster to draw in other combustible
gas such as common coal gas, or what is known as water gas, or again, it may
draw in hydrocarbon vapours, or liquid, or the latter may be forcibly injected into
the circulating apparatus, & these circulating in more or less quantity, in a
highly heated condition, readily reduce any red oxide of iron, or rust, which may
be accidentally, designedly, or naturally, formed upon the iron, or steel, articles
under treatment.
Also, when it is required to heat up the pipes (e), rapidly, gas may be drawn
in through the pipe (f), by means of the pipe (2), & air may also be admitted
through the holes (n), & caused to burn with such gas, or it may be with gas other-
wise procured than from the gas producer, or with hydrocarbons, liquid or gaseous,
as already explained. Or in the case of a thin fire, completed products of combus-
tion drawn from the top of the fire place (A), may be made to circulate through
the pipes (c), & so rapidly heat them up.
A gas producer is convenient when working is fairly continuous, & an ordinary
thin fire where it is intermittent; but I do not necessarily confine myself to either
of these arrangements, for when a number of furnaces are working together, it
would be desirable to have the gas producer, or producers, separate altogether
from the oxidising chambers, & fluid heating apparatuses; & in such a case, the
gas may be that known as water gas," & led to any point where combustion
is desired.
Another portion of my invention refers to a method of cooling the iron, or steel,
articles in the chamber (B), before withdrawal, & this I do by closing the inlets
from the pipe (f), to the heating pipes (c), & causing the pipe (f) to deliver the
circulating fluid through another large pipe (9), situate outside of the furnace,

page_text: a valve (), being employed to close such pipe when it is not required, as in similar
manner, is a valve (S), used to close the pipe (p), when it is not required.
I cause the hot fluid passing through (7) to come into contact with a cooling
medium such as, for example, a jet of water spray, which may itself be evaporated,
& the now thoroughly cooled fluids pass on through the pipe (4), to the chamber (13),
abstract heat from the hot articles therein, & thence, by the action of the jet
exhauster, again through the cooler, & so on continuously until the articles are
deemed to be sufficiently cool to be withdrawn.
Other circulating arrangements may be used besides a jet propeller, such as a
fan, or spiral conveyer in the pipe (f), but since steam is, in the main, the
oxidising agent; it is also in most cases the most useful, and convenient, propell-
ing agent for the circulating fluids.
The heating arrangement may obviously be reversed in action, that is to say,
the products of combustion from (A), may pass inside a set of pipes, & the circulating
fluid be caused to pass outside the same pipes this being merely a matter of detail.
The heating of the circulating fluid may also be intermittent, that is to say, the
products of combustion may first be caused to pass through chequer work of
refractory material & afterwards the products of combustion may be diverted to
another mass of chequer work, & the circulating fluid then made to pass through
that chequer work which has been already heated, & vice-versa, as is often done
in heating air for regenerative furnaces.
Having now particularly described and ascertained, the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is: -
(1) In a furnace for producing a coating of magnetic oxide of iron upon iron,
& steel, articles; causing the operating fluid to continually circulate from the
chamber in which the articles to be treated are placed; thence through a heating,
or cooling, apparatus to the chamber again, & so on continuously, such circulation
being produced by means of a steam jet, or fan, or spiral conveyor, or similar
apparatus, any surplus fluid being rejected, or discharged at suitable points, sub-
stantially as herein described, and illustrated.
(2) Causing the circulating apparatus to draw in, oxidising, or deoxidising
substances, and to force these to circulate in a similar manner for the purposes
herein described.
(3) The particular design of furnace as herein described, and illustrated, as
forming one method of efficiently carrying out my invention.
A 1000
ANTHONY SPENCER BOWER.