A PROCESS FOR THE PARTIAL ELIMINATION OF THE NITROGEN FROM THE PRODUCTS OF COMBUSTION, AND FURNACES AND APPARATUS CONNECTED THEREWITH
Year: 1868

page_text: LETTERS PATENT to Charles Schinz, of No. 27, Faubourg de Saverne,
Strasbourg, in the Empire of France, Engineer, for the Invention
of "A PROCESS FOR THE PARTIAL ELIMINATION OF THE NITROGEN FROM
THE PRODUCTS OF COMBUSTION, AND FURNACES AND APPARATUS CONNECTED
THEREWITH.”
Sealed the 28th August 1868, and dated the 4th March 1868.
PROVISIONAL SPECIFICATION left by the said Charles Schinz at
the Office of the Commissioners of Patents, with his Petition, on
the 4th March 1868.
I, CHARLES SCHINZ, of No. 27, Faubourg de Saverne, Strasbourg, in
the Empire of France, Engineer, do hereby declare the nature of the
said Invention for "A PROCESS FOR THE PARTIAL ELIMINATION OF THE NITROGEN
FROM THE PRODUCTS OF COMBUSTION, AND FURNACES AND APPARATUS CONNECTED
THEREWITH," to be as follows:-
This process, which is intended to be applied to blast and other
furnaces, has for its object to eliminate a portion of the nitrogen which
forms part of the products of combustion by the use of carbonic acid
[Price 8d.]

page_text: obtained by the decomposition of limestone in retorts or muffles, whereby
a great saving of fuel is effected.
When a volume of carbonic acid is carried over coals, or over any
substances containing carbon in a state of incandescence, half a volume
of oxygen will be absorbed, and two volumes of carbonic oxide will be
formed. In the case of the usual process of heating by gas as well as
in the blast furnace carbonic acid is invariably formed in the first
instance, and when there is an excess of carbon present this carbonic
acid becomes transformed into a double volume of carbonic oxide. But
in these cases the resulting carbonic oxide is invariably mixed with that
quantity of nitrogen which is due to the oxygen contained in the atmo-
spheric air which has been used during the process of combustion, and
it amounts to 3.77 volumes for each volume of oxygen. Therefore
2 volumes of carbonic oxide + 3.77 volumes of nitrogen are formed in
the first instance, and these by the process of combustion are converted
into 2 volumes of carbonic acid +7.54 volumes of nitrogen; whilst by my
process, which I shall hereafter describe, the gas intended to be used for
the purpose of combustion consists of only 2 volumes of carbonic oxide
which through the process of combustion produce 2 volumes of carbonic
oxide 3.77 volumes of nitrogen. Now as the temperature increases in
intensity inversely as the volume of the products of combustion it is
not difficult to perceive how great the economical value of my process
must be.
in its application to blast furnaces as well as to gas furnaces
the carbonic oxide is injected simultaneously with the atmospheric air
through separate tuyeres upon the incandescent fuel, so that the com-
bustion of the carbonic oxide is effected in the very midst of the fuel,
namely, as far as the blast furnace is concerned in the hearth, and in
the case of a gas furnace in the gas generator, where owing to the
presence of an
excess of carbon and through the resulting high tem-
perature the carbonic acid which is one of the products of combustion
is again transformed into carbonic oxide. In these cases therefore we
obtain 4 volumes of carbonic oxide and only 3.77 volumes of nitrogen.
According to the processes hitherto in use the blast furnace gases are
composed or 654 per cent. of nitrogen, and 34.6 per cent. of carbonic
oxide, whilst according to my process they consist of over 48.5 per cent.
of nitrogen and 61.5 per cent. of carbonic oxide. The last-mentioned
gases are therefore richer by from 48 to 49 per cent. than the former
ones, and accelerate as my experiments have proved the reduction of the
ores in the self-same proportion, whilst those gases which escape at the

page_text: mouth of the furnace also acquire a very considerably higher calorific
value. If on application of this process to gas furnaces a temperature
exceeding the requirements of the operations for which it is intended
should be developed it will be sufficient to reduce the gas generator or the
amount of fuel consumed in a given time, whence it is evident that my
process is applicable to all pyrotechnical apparatus which are employed in
industrial or metallurgical purposes.
I will now proceed to describe the process itself:-The most simple
as well as the most economical method of generating carbonic acid on
a large scale is the decomposition by heat of the carbonate of lime
(limestone), the residuary product of which in the shape of burnt or
quicklime finds nearly everywhere a ready market. The burning of
the limestone takes place in retorts or muffles, which are mounted in
ovens of a peculiar construction, and the size of which is determined by
the amount of carbonic acid given off by the limestone intended to be
used as well as by the quantity required in a given time. At a tem-
perature of 1000° the decomposition of the carbonate of lime requires about
two hours.
1 cubic metre of carbonic acid contains 0-5364 kilogrammes
of carbon, and 1 kilogramme of carbonate of lime yields 0.44 cubic metres
of carbonic acid. My object being to replace one-fourth of the carbon
which serves the purpose of combustion in any furnace by the carbon
contained in the carbonic acid derived from the decomposition of lime-
stone, the quantity of carbonic acid required, for instance, for a furnace
consuming 100 kilogrammes per hour will be = 100 kilogrammes = 25
kilogrammes, therefore 25 kilogrammes = 46.6 cubic metres of carbonic
acid inust be produced per hour. Now if 1 kilogramme of carbonate of
lime yields in two hours 0-44 cubic metres of carbonic acid, it follows that
for each cubic metre of carbonic acid 4.545 kilogrammes of limestone
must be under decomposition, and the capacity of the retorts or muffles
must therefore be 211.8 kilogrammes, or 0.163 cubic metre. The
carbonic acid gas thus produced is subsequently, in order to convert
it into carbonic oxide, carried through a series of other retorts or muffles
disposed in the same oven as those in which the limestone is burnt, and
which are filled with small refuse pieces or particles of coke or other
combustible material in a state of incandescence. For the calculation
of the requisite capacity of these retorts or muffles the following experi-
mental results will serve:-0.00,474 cubic metres of carbonic acid
per hour requires at the temperature of 1000° one square metre of

page_text: contact surface for its conversion into carbonic oxide, therefore 1 cubic
metre of carbonic acid per second requires to be brought in contact with
210 square metres of surface presented by such pieces or particles of
coke.
The effect and determination of the contact surface of various kinds of
fuel are the object of a treatise which has been published in Dingler's
Journal, volume CLXXXI. page 1, and in translation by H. Fiêvet, in
the "Annales du Génié Civil," page 281, series for 1867, to both of
which publications I herein refer. According to the above-mentioned
example, where 46.6, say 47, cubic metres of carbonic acid are supposed
to require conversion into carbonic oxide, we have 177 0.013055 cubic
metre per second, whence by the equation 0-00474: 1 = 0.013055 : 2-754,
we should have to provide for a minimum contact surface in the retorts
or muffles of 2.754 square metres. In the treatise above referred to it
will be found that one cubic metre of fuel in pieces of the following
dimensions offer respectively the under-mentioned contact surface, viz.,
pieces of 1 centimetre diameter offer 314 square metres, those at 2 centi-
metres diameter offer 157 square metres, and those of 3 centimetres
diameter offer 104 square metres. These figures shew that supposing
the capacity of the retorts in which the carbonic acid is to be reduced
were to be made 30 times as large as it is absolutely required to be in
order to avoid the too frequent feeding, the retorts would nevertheless be
of a very moderate size. On extending these calculations to the require-
ments of a blast furnace having a consumption of 900 kilogrammes of
carbon per hour it will be found that 225 kilogrammes of this quantity
would have to be supplied in the shape of carbonic acid, of which con-
sequently 420 cubic metres would have to be produced per hour. In
this case the retorts or muffles required for decomposing the limestone
must have a capacity of 1.4423 cubic metres, and those intended for the
reduction of the carbonic acid 30 × 0.3 = 9 cubic metres, supposing the
pieces of coke with which they are filled to be small enough. This
comparatively small size of the retorts or muffles admits of their being
heated to 1000° by the waste heat of the gas furnace, or in the case of
a blast furnace by the gases evolved from the latter. The carbonic oxide
gas thus formed is conveyed into a gasometer, whose dimensions must
be adapted to the size of the works, and from this reservoir it is supplied
to the blast engine, and thereby injected either into the blast furnace
or into the gas generator. At the same time atmospheric air is supplied

page_text: by means of another blast .engine or apparatus, and this in such a
manner that the proper relation between the volumes of gas and air is
strictly maintained. The tuyeres are concentric; those placed internally
serve for the conveyance of the gas. It is necessary during their
progress to heat both the gas and the air to 400° for the purpose of main-
taining the temperature produced by the combustion at an elevation
which shall be sufficient to convert the carbonic acid into carbonic
oxide; but as the volume to be injected is much smaller than it would
be under ordinary circumstances it is possible to accomplish even this
by the waste heat of the gas furnace or by the blast furnace gases.
The application of my process to gas generators of the ordinary
construction requires some modifications, inasmuch as it becoines
necessary simultaneously to inject both gas and air into it.
In
My process for the partial elimination of the nitrogen from the pro-
ducts of combustion is applicable to a great variety of purposes. Gas
generators to which my process is to be applied I construct and work as
follows: In the arched interior of the generator I form two oblong
rectangular chambers reaching from end to end of the interior of the
generator, which chambers act as the furnaces. Along both sides of
each furnace are placed the channels and pipes for the air and the
carbonic acid gas, the latter within the former. I prefer to make
the furnaces of a length suitable for placing four tuyères in each side;
the air tuyères may be formed of the brickwork, enclosing the gas tuycres
concentrically. The furnaces which are open at the bottom rest each
upon a cast-iron plate supported by brickwork in the usual manner.
the open space or chamber formed under the furnace I place a carriage,
which carries a second plate fitting accurately against the sides and ends
of the first plate. This second plate acts as a sliding bottom to the
furnace. At the front end of the sliding bottom is formed a rectangular
feed box of the length and width of the furnace. The feed box is pro-
vided with a loose bottom, which can be raised to the surface of the
sliding bottom and again lowered by means of two vertical screws
actuated by a worm wheel nut and worms, or by equivalent means. For
supplying the furnace with fuel the carriage is drawn forward so as to
bring the feed box outside the generator. The box is now filled with
fuel (which may be small coal (slack) or even coal dust or other refuse)
and pushed back into position exactly under the furnace, when its
bottom is gradually raised by the said gear, and the fuel thereby intro-

page_text: duced into the furnace. The carriage is now again drawn forward, and
the fuel resting on the sliding bottom, the box bottom is lowered and
the box refilled with fuel ready to be transferred to the furnace. The
ashes which will by degrees accumulate upon the fuel will fall over the
sides of the furnace, whence they can be from time to time scraped out
through doors fitted in the front of the generator.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Charles Schinz in the Great Seal Patent Office
on the 3rd September 1868.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CHARLES
SCHINZ, of No. 27, Faubourg de Saverne, Strasbourg, in the Empire of
France, Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Fourth day of March, in the year
of our Lord One thousand eight hundred and sixty-eight, in the thirty-
first year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Charles Schinz, Her special licence
that I, the said Charles Schinz, my executors, administrators, and
assigns, or such others, as I, the said Charles Schinz, 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 of "A PROCESS FOR
THE PARTIAL ELIMINATION OF THE NITROGEN FROM THE PRODUCTS OF COMBUSTION,
AND FURNACES AND APPARATUS CONNECTED THEREWITH," upon the condition
(amongst others) that I, the said Charles Schinz, 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
to be performed, and cause the same to be filed 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 I, the said Charles Schinz, do hereby
declare the nature of my said Invention, and in what manner the

page_text: same is to be performed, to be particularly described and ascertained in
and by the following statement, reference being had to the accompanying
Drawings forming a part of this Specification:-
This process, which is intended to be applied to blast and other furnaces,
has for its object to eliminate a portion of the nitrogen which forms part
of the products of combustion by the use of carbonic acid obtained by the
decomposition of limestone in retorts or muffles, whereby a great saving
of fuel is effected.
When a volume of carbonic acid is carried over coals or over any
substances containing carbon in a state of incandesence half a volume
of oxygen will be absorbed, and two volumes of carbonic oxide will be
formed. In the case of the usual process of heating by gas, as well as
in the blast furnace, carbonic acid is invariably formed in the first
instance, and when there is an excess of carbon present this carbonic
acid becomes transformed into a double volume of carbonic oxide; but
in these cases the resulting carbonic oxide is invariably mixed with that
quantity of nitrogen, which is due to the oxygen contained in the
atmospheric air which has been used during the process of combustion,
and it amounts to 3.77 volumes for each volume of oxygen. Therefore
2 volumes of carbonic oxide +3.77 volumes of nitrogen are formed in
the first instance, and these by the process of combustion are converted
into 2 volumes of carbonic acid + 754 volumes of nitrogen, whilst
by my process, which I shall hereafter describe, the gas intended to be
used for the purpose of combustion consists of only 2 volumes of
carbonic oxide, which through the process of combustion produce 2
volumes of carbonic oxide + 3.77 volumes of nitrogen. Now as the
temperature increases in intensity inversely as the volume of the
products of combustion it is not difficult to perceive how great the
economical value of my process must be. In its application to blast
furnaces as well as to gas furnaces the carbonic oxide is injected
simultaneously with the atmospheric air through separate tuyères upon
the incandescent fuel, so that the combustion of the carbonic oxide is
effected in the very midst of the fuel, namely, as far as the blast furnace
is concerned in the hearth, and in the case of a gas furnace in the gas
generator, where owing to the presence of an excess of carbon and
through the resulting high temperature the carbonic acid, which is one
of the products of combustion, is again transformed into carbonic oxide.
In these cases therefore we obtain 4 volumes of carbonic oxide and only

page_text: 3.77 volumes of nitrogen. According to the processes hitherto in use
the blast furnace gases are composed of 65.4 per cent. of nitrogen and
34.6 per cent. of carbonic oxide; whilst according to my process they
consist of over 48.5 per cent. of nitrogen, and 51-5 per cent. of carbonic
oxide. The last mentioned gases are therefore richer by from 48 to 49
per cent. than the former ones, and accelerate, as my experiments have
proved, the reduction of the ores in the self-same proportion, whilst those
gases which escape at the mouth of the furnace also acquire a very
considerably higher calorific value. If on application of this process to
gas furnaces a temperature exceeding the requirements of the operations
for which it is intended should be developed it will be sufficient to reduce
the gas generator or the amount of fuel consumed in a given time, whence
it is evident that my process is applicable to a variety of apparatus employed
for industrial or metallargical purposes.
I will now proceed to describe the process itself:-The most simple
as well as the most economical method of generating carbonic acid on
a large scale is the decomposition by heat of the carbonate of lime
(limestone), the residuary product of which in the shape of burnt or
quicklime finds nearly every where a ready market. In stating the
degrees of temperature in all cases throughout this Specification I refer
to the " 'centigrade" scale. The burning of the limestone takes place
in retorts or muffles, which are mounted in ovens of a peculiar
construction, and the size of which is determined by the amount of
carbonic acid given off by the limestone to be used as well as by the
quantity required in a given time. At a temperature of 1000° the
decomposition of the carbonate of lime requires about two hours; 1 cubic
metre of carbonic acid contains 0.5364 kilogrammes of carbon, and 1
kilogramme of carbonate of lime yields 0.44 cubic metres of carbonic
acid. My object being to replace one-fourth of the carbon which serves
the purpose of combustion in any furnace by the carbon contained in
the carbonic acid derived from the decomposition of limestone, the
quantity of carbonic acid required, for instance, for a furnace consuming
100 kilogrammes per hour will be = 100 kilogrammes = 25 kilogrammes.
Therefore 25 kilogrammes 46.6 cubic metres of carbonic acid must
be produced per hour. Now if one kilogramme of carbonate of lime
yields in two hours 0.44 cubic metres of carbonic acid it follows that
for each cubic metre of carbonic acid 4.545 kilogrammes of limestone
must be under decomposition, and the capacity of the retorts or muffles
1

page_text: must therefore be 211.8 kilogrammes, or 0.163 cubic metre. The
carbonic acid gas thus produced is subsequently, in order to convert it
into carbonic oxide, carried through a series of other retorts or muffles
disposed in the same oven as those in which the limestone is burnt, and
which are filled with small refuse pieces or particles of coke or other
combustible material in a state of incandescense. For the calculation
of the requisite capacity of these retorts or muffles, the following
experimental results will serve:-0.00474 cubic metres of carbonic acid
per hour requires at the temperature of 1000° one square metre of
contact surface for its conversion into carbonic oxide; therefore 1 cubic
metre of carbonic acid per second requires to be brought in contact
with 210 square metres of surface presented by such pieces or particles of
coke.
The effect and determination of the contact surface of various kinds
of fuel are the object of a treatise which has been published in Dingler's
Journal, volume CLXXXI. page 1, and in translation by H. Fievet, in
the "Annales du Gènie Civil," page 281, series for 1867, to both of
which publications I herein refer. According to the above-mentioned
example, where 46.6, say 47, cubic metres of carbonic acid are supposed
to require conversion into carbonic oxide, we have 3000=0.013055 cubic
metre per second, whence by the equation 0.00474: 1-0-013055: 2-754,
we should have to provide for a minimum contact surface in the retorts
or muffles of 2-754 square metres. In the treatise above referred to it
will be found that one cubic metre of fuel in pieces of the following
dimensions offer respectively the under mentioned contact surface, viz.,
pieces of 1 centimetre diameter offer 314 square metres, those of
2 centimetres diameter offer 157 square metres, and those of 3 centi-
metres diameter offer 104 square metres. These figures shew that
supposing the capacity of the retorts in which the carbonic acid is
to be reduced were to be made thirty times as large as it is absolutely
required to be in order to avoid the two frequent feeding the retorts
would nevertheless be of a very moderate size. On extending these
calculations to the requirements of a blast furnace having a consumption
of 900 kilogrammes of carbon per hour it will be found that 225
kilogrammes of this quantity would have to be supplied in the shape of
carbonic acid, of which consequently 420 cubic metres would have to
be produced per hour. In this case the retorts or muffles required for
decomposing the limestone must have a capacity of 1.4423 cubic metres,

page_text: and those intended for the reduction of the carbonic acid 30×0.3 == 9
cubic metres, supposing the pieces of coke with which they are filled
to be small enough. This comparatively small size of the retorts or
muffles admits of their being heated to 1000 degrees by the waste heat
of the gas furnace, or in the case of a blast furnace by the
gases evolved
from the latter. The carbonic oxide gas thus formed is conveyed into
a gasometer whose dimensions must be adapted to the size of the works,
and from this reservoir it is supplied to the blast engine and thereby
ejected either into the blast furnace or into the gas generator. At the
same time atmospheric air is supplied by means of another blast engine
or apparatus, and this in such a manner that the proper relation between
the volumes of gas and air is strictly maintained. The tuyères are
concentric; those placed internally serve for the conveyance of the gas.
It is necessary during their progress to heat both the gas and the air
to 400 degrees for the purpose of maintaining the temperature produced
by the combustion at an elevation which shall be sufficient to convert
the carbonic acid into carbonic oxide; but as the volume to be injected
is much smaller than it would be under ordinary circumstances it is
possible to accomplish even this by the waste heat of the gas furnace or
by the blast furnace gases.
The application of my process to gas generators of the ordinary con-
struction requires some modifications, inasmuch as it becomes necessary
simultaneously to inject both gas and air into it.
My process for the partial elimination of the nitrogen from the
products of combustion is applicable to a great variety of purposes.
Gas generators to which my process is to be applied I construct and
work as follows:-In the arched interior of the generator I form two
oblong rectangular chambers reaching from end to end of the interior
of the generator, which chambers act as the furnaces. Along both sides
of each furnace are placed the channels and pipes for the air and the
carbonic acid gas, the latter within the former. I prefer to make the
furnaces of a length suitable for placing four tuyères in each side,
the air tuyère may be formed of the brick work enclosing the gas
concentrically. The furnaces which are open at the bottom rest each
upon a cast-iron plate supported by brickwork in the usual manner.
In the open space or chamber formed under the furnace I place a
carriage which carries a second plate fitting accurately against the sides
and ends of the first plate. This second plate acts as a sliding bottom

page_text: to the furnace. At the front end of the sliding bottom is formed a
rectangular feed box of the length and width of the furnace. The feed.
box is provided with a loose bottom which can be raised to the surface
of the sliding bottom and again lowered by means of two vertical screws
actuated by a worm wheel nut aud worms, or by equivalent means.
For supplying the furnace with fuel the carriage is drawn forward so
as to bring the feed box outside the generator. ihe box is now filled
with fuel (which may be small coal (slack) or even coal dust or other
refuse) and pushed back into a position exactly under the furnace,
when its bottom is gradually raised by the said gear and the fuel
thereby introduced into the furnace. The carriage is now again drawn
forward, and the fuel resting on the sliding bottom, the box bottom is
lowered and the box refilled with fuel ready to be transferred to the
furnace. The ashes which will by degrees accumulate upon the fuel
will fall over the sides of the furnace, whence they can be from time
to time scraped out through doors fitted in the front of the generator.
DESCRIPTION OF THE DRAWINGS.
Figure 1 illustrates one method of constructing my improved gas
generators in horizontal section through the line M, N, Figure 2;
Figure 2 is a vertical cross section through the line D, E, F, Figure 3;
Figure 3 is a longitudinal vertical section through the line A, B, C,
Figure 2; Figure 4 is an under side view of the carriage and feed box
forming part of the said generator.
4 is the air
the channel
The platform
That end of the platform
chamber or box 8 formed
other end of the platform
Into the hearths or furnaces 1, 1, of the generator the tuyères 2 for
the air and the tuyeres 3 for the carbonic oxide gas open.
or blast pipe in connection with the blast engine, and 5
which receives the carbonic oxide gas through the tubes 6.
or top 7 of a carriage fits accurately against the cast-iron frame upon
which the brickwork of the furnace 1 rests.
shown immediately under the furnace 1 has a
in it which acts as the feed box, whilst the
serves as a sliding bottom to the furnace 1. This box 8, which is of the
same length and width as the furnace itself, is fitted with a piston 9
which can be raised to the surface of the box 8 and again lowered by
means of the two screws 10, worm wheel nuts and worm 11, and
handle 12. In the position which the carriages usually occupy the
furnaces 1 are closed by the platform or sliding bottom 7, and the front

page_text: end of the carriage with the feed box 8 projects beyond the generator.
For supplying the furnace with fuel the feed box 8 is filled with the
coal or other fuel and the carriage is pushed back till the feed box 8
is exactly in position under the furnace 1, as represented in Figures 2
and 3. The fuel in the feed box is now raised to the furnace by means
of the piston 9 and gearing connected with the same, and when the top
of the piston 9 has come to the level of the platform the carriage is
drawn forward again and the chamber refilled with fuel ready for the
next charge. The sides of the furnaces are bevelled off at the top to
allow the ashes which are gradually raised to the surface to fall over
into the spaces 13, whence they are from time to time removed through
doors fitted in the ends of the generator.
It is obvious that fuel of the
worst description, even in the condition of powder, can be used in my
improved generators. The said generators are also applicable for making
ordinary gas, the tuyères 3 and channels and pipes 5 and 6 being in this
case dispensed with.
Having thus fully described my said Invention, and shown how
the same may be conveniently and advantageously carried into practice,
I claim,
First. The partial elimination of nitrogen from the products of
combustion by the means herein described or by means substantially the
same.
Second. The construction of the gas generators, substantially as set
forth.
In witness whereof, I, the said Charles Schinz, have hereunto set
my hand and sea!, this Twenty-ninth day of August, in the year
of our Lord One thousand eight hundred and sixty-eight.
CHARLES SCHINZ. (L.S.)