Improved Process and Apparatus for the Production of Oxygen Gas.
Year: 1890

page_text: Date of Application, 20th May, 1890
Complete Specification Left, 9th Dec., 1890-Accepted, 7th Feb., 1891
PROVISIONAL SPECIFICATION.
Improved Process and Apparatus for the Production of Oxygen Gas.
I, ROBERT DAVY BOWMAN, of No. 80, Lordship Lane, East Dulwich, in the
County of Surrey, Lighting Engineer, do hereby declare the nature of this inven-
tion to be as follows:-
This invention relates to an improvement upon the well known manganate of
soda process for the production of free oxygen.
An iron or other convenient vessel is half filled with sodium hydrate, and the
whole is brought to a red heat, and kept so until it has finished boiling. At this
point I add small portions or quantities of dried sesquioxide or peroxide of manganese
until the whole becomes a plastic granular mass after continued stirring. When the
granulations refuse to stick together, they are dusted over with black oxide of
copper, and then exposed to a red heat in a full current of air, until they assume a
dark green or black colour through absorption of oxygen. They are then packed
in iron or other tubes, which may be separate, in sets, or in series, and kept at a
dull red heat. If steam is now passed over these granulations, their surfaces will be
decomposed into sodium hydrate, manganese, and free oxygen, which latter can be
collected in any convenient holder. When the whole of the oxygen has been given
off, the steam is replaced by air, whereupon the oxygen will be absorbed and
nitrogen liberated, and in a few minutes steam can be passed over again to liberate
the oxygen, and so on.
In carrying my invention into effect, and in order to save all oxygen, I provide
suitable sets of tubes, as mentioned above, connected from each series by valves or
equivalent means, and when steam is first admitted to the first set of tubes, a certain
amount of air very rich in oxygen is liberated. This mixture would, in the ordinary
way, run to waste; but, by opening the valve or cock into the next set, or series, of
tubes, the oxygen liberated is absorbed by them, and the nitrogen is allowed to go
free and to pass through until the pure oxygen is liberated in the first set.
When it is ascertained that pure oxygen is coming from the first set of tubes, the
valve is shut to the second set; and air is allowed to pass through the second set.
It will be obvious that when the whole of the oxygen has been liberated from the
first set of tubes, the second set of tubes will have absorbed sufficient oxygen from
the air to be treated in the same manner as the first set, when air can be forced
over the first set with the mixture of oxygen and air from the second set, and so on.
Dated this 20th day of May 1890.
PHILLIPS & LEIGH,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improved Process and Apparatus for the Production of Oxygen Gas.
I, ROBERT DAVY BOWMAN, of No. 80, Lordship Lane, East Dulwich, in the
County of Surrey, Lighting 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 :-
This invention relates to improvements upon the well known manganate of soda
method for the production of free oxygen, and consists of two parts, firstly, it
relates to the process, and especially to the preparation in a suitable manner of
the manganate material, and to the management of the gaseous flow so as to

page_text: prevent the initial effluxes of oxygen, which are diluted with an excess of atmos-
pheric air, from being lost; and secondly, it relates to the apparatus by means
of which the oxygen is produced.
In carrying my invention into effect, a closed vessel of iron, or other material
suitable for the purpose, and of a proper shape, is half filled with sodium hydrate,
and the whole is raised to a red heat, and kept at that temperature until
ebullition has ceased. The object of this is to expel all the water and leave the
soda as pure as the present invention requires. Small quantities of dried sesquioxide
or peroxide of manganese, preferably the former, are next added to the dried soda
until the whole mass attains, after continued stirring, a plastic granular condition.
This stirring is effected by means of a plain stirring rod, or by any suitable device.
Little or no air is allowed to come into contact with the granules up to this stage.
No chemical action takes place, and the mixture of the soda and manganese is
only a mechanical one. I cannot give the exact proportions of sodium hydrate and
manganese salt because they both vary, as ordinarily met with, in point of purity,
but the average proportions are two thirds of manganese to one of the hydrate.
As soon as the granules refuse to stick together they are dusted over with
black oxide of copper. This dusting has the effect of preventing them sticking
together. They are then exposed to a red heat in a full current of air until they
assume a dark green or black colour as a consequence of their absorption of oxygen
from the said current. The granules prepared in this way will withstand a very
high temperature without fusing, and, as a consequence, a large surface will be
exposed to the action of the alternate currents of air and steam hereafter
described. The above described process of preparing the granules occupies about
half an hour.
The granules thus prepared are ready to be introduced into the tubes or tubular
retorts of the oxygen producing apparatus.
The well known process for the preparation of oxygen gas by means of manganate
of soda consists in heating the soda compound in retorts made of iron, or other
suitable material, and keeping it at a dull red heat. Steam is then passed through
the retorts with the result that the material is decomposed into sodium hydrate,
manganese, and free oxygen. The oxygen is then conveyed to any convenient gas
holder. As soon as all the free oxygen has been given off, the current of steam is
replaced by one of atmospheric air. The oxygen of the latter is absorbed by the
material, and its nitrogen isolated. When the absorption of oxygen has ceased, the
air current is cut off, and that of steam again turned into the retorts to liberate
the absorbed oxygen, and so on.
As I work the process, the treatment with air and steam is frequently and
automatically alternated, so that the surfaces of the granules are mainly operative.
When thus treated, the granules retain their form indefinitely which would not be
the case if, at each alternation, a complete conversion of the material took place.
When steam is first admitted to the retorts, oxygen, mixed with some remaining
nitrogen, is expelled, this, which has hitherto been wasted, I utilize by passing it
into other retorts in which oxygen is being absorbed. A more complete saturation
of the material with oxygen is thereby obtained, and an increased yield results.
Although it is not essential, I prefer to provide two sets of retorts, and so to
work them that whilst absorption of oxygen is going on in one set, oxygen gas is
being delivered from the other set. I provide each set with cocks or valves for
alternately admitting air and steam, and for drawing off the gases, and I provide
apparatus for the automatic control of all these cocks or valves. I also provide a
separate cock or valve for drawing off the impure or dilute oxygen gas, which
cock or valve also may be automatically controlled.
In order that both the process and apparatus constituting my invention may
be thoroughly understood, I will describe them in detail, referring in so doing to
the accompanying drawings which are to be taken as part of this Specification and
read therewith.
Fig. 1 is a half sectional front elevation, partly in section, of a complete

page_text: apparatus of one hundred retorts arranged as two sets in series.
the line A-B of Fig. 3.
IU IS LAACH
Fig. 2 is a half sectional side elevation taken on the line C-D of Fig. 3.
Fig. 3 is a half sectional plan taken on the line E-F of Fig. 1.
A is the furnace for keeping the retorts at the proper temperature. B, B are
the retorts of one set; and B', B¹, the retorts of the other.
C, C¹ are mains connected, respectively, to the series of retorts B and B¹ by
pipes c, c¹.
D, D are branches from these mains, respectively, to the pair of two-way
cocks E, E. These communicate in each case with the interior of the plug of
the cock.
F is the air-supply main, and G, the steam-supply main.
,
Both the last mentioned mains deliver into the shell or body common to both
the cocks E, E¹. One of these cocks is shut to the air supply and open to the
steam supply whilst the other is in the opposite position. After a time both
cocks are turned simultaneously and the connections reversed.
H, H' are the two gas mains for receiving the oxygen and nitrogen gases as
These mains are
these are given off alternately from the two sets of retorts.
connected to the said sets of retorts, respectively, by small pipes h, .
I, I are the respective branches to the pair of two-way cocks J, J.
the oxygen, and, the nitrogen exit ports in the respective plugs.
are hollow for the greater part of their length, the gases entering them
smaller ends.
1, 2 are
The plugs
at their
The 4 two-way cocks E, E', and J, J, are of the same internal construction, and
the two plugs of each pair are always in opposite. positions. For instance, if the
cocks E is passing steam, the cock E is passing air, and vice versa. So with the
cocks J, J if one is passing oxygen, the other is passing nitrogen, and vice versa.
Provided that the alternate passage of their respective gases and fluids is provided
for, the four cocks above mentioned may be of any convenient construction.
All the four cock-plugs being set in their proper relative positions, they are fixed
thereto by a link K, to which half cranks k, k¹, k², k³, fast upon the heads of the
plugs of the respective cocks, are pivotted.
Lis the nitrogen exhaust.
Mis the oxygen main leading from the cocks J, J, to the special cock N
described further on; and O is the branch to the bottom of the closed cooler P.
This latter is kept supplied with cold water fed into it through a pipe p, while
provision is made by means of a pipe for the hot water to flow away.
The cooler also acts as a water-seal for a purpose to be explained in the proper
place.
Q is the oxygen main from the cooler to the storage reservoir.
The plug of the special cock N above mentioned is hollow like those of the
cocks F, F, J, J', but, unlike them it has only one delivery port n which, it is to
be noted, is of comparatively small area. The shell of the cock has two ports n', n²,
opposite to each other, and these open respectively into two by-passes R, R',-one
for each series of retorts. These by-passes deliver into the branches D, D', and
so into the two series B, B', respectively.
The plug of the cock N is axially fast to the shaft N' supported in suitable
bearings. N2 is a driving pulley keyed on the same shaft.
The motion of the plug of the cock N is transferred to the link K by two pairs
of mitre gears n², n³, n, n³, a half crank ne, and a connecting rod n', being thereby
converted from one of rotation into a continuous reciprocating motion on the part of-
the said link. For each rotation of the plug, the link makes a double stroke,
i.e., one forwards and one backwards. Provided that proper relative motions are
preserved, any other gear may be used to connect these members of the apparatus.
The figures illustrate the following stage of the process and the corresponding
positions of the several parts of the apparatus. Steam is being sent through the

page_text: bottom series of the retorts and deoxidizing the granules therein, pure oxygen
being driven to the reservoir. Air is being sent through the top series.
The operation of my invention, in an apparatus constructed as illustrated, is as
follows:-
The retorts B, B1 having been filled and raised to the proper temperature, the air
and steam at a suitable low pressure, are turned on into the respective supplies F
and G, and the motor started.
As the steam enters the series B, some oxygen is liberated, and this initial efflux,
diluted with air as already explained, flows through the pipes h, the main H, the
branch I, the cock J, its port, and the main M into the cock N. When this
quantum of oxygen and air reaches the said cock, the port n is communicating
through the port n' with the by-pass R'; through which, the branch D', the main CT,
and the pipes c', the mixture flows into the top series B', wherein the oxygen
absorbed by the granules which have been deoxygenated. It is because the
mixture finds the branch O sealed against it by the water in the cooler, that it
takes the open course through the cock N. The rate of rotation of the cock N is
so timed as to close the ports n,.n', as soon as pure oxygen begins to flow from the
retorts, so that after the mixture of air and oxygen has passed the cock, the pure
oxygen must flow or be driven, by the pressure of the oxygen behind it, down the
branch O into the water of the cooler P, and thence through the main Q to the
reservoir. The steam accompanying the gas into the coolers is condensed there.
By the time all the free oxygen from the series B has passed the cock J', the motion
of the link K to the right has moved the port j' downwards to the left away from
the main M, and opened the port to the nitrogen exhaust L.
At the same time,
the steam supply is cut off from the said series B, and the air supply turned
into the retorts thereof by the reversal of the cock E.
As the air enters the said retorts, it parts with its oxygen to the already
deoxygenated granules, and the isolated nitrogen is driven through the pipes lt,
the main H, the branch I, the cock J, the port j, into the exhaust L.
While the oxygenation described in the last paragraph has been proceeding,
steam has been flowing through the retorts of top series, the phenomena being
counterparts of those already described with reference to the boitom series.
The time occupied by a complete cycle of operations (corresponding to an
entire rotation of the cock N) is dependent more or less on the temperature;
but when working at a dull red heat (which is preferred) it will be suitable if the
duration of the cycle be seven minutes.
Although the drawings illustrate the conduct and embodiment of my invention
in a two-series multiple retort apparatus, it must be distinctly understood that my
invention is not confined in this respect, but may be applied to a single acting
apparatus.
I wish it to be distinctly understood that I make no general claim to the
production of free oxygen by the action of alternate currents of steam and air upon
manganate of soda.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is,
1. The preparation of granulated material to be used in the production of oxygen
gas, by subjecting sodium hydrate to a red heat, adding thereto sesquioxide or
peroxide of manganese, stirring constantly in such manner as to reduce the material
to a granular state, then dusting over the granules with black oxide of copper, and
finally subjecting them to a red heat in a current of air, substantially as herein
described.
2. In the production of oxygen gas by the absorption of the same from
atmospheric air and its subsequent liberation, returning the impure or dilute
oxygen gas at first obtained into retorts or vessels in which absorption is going on,

page_text: whereby, in consequence of these retorts being supplied with gas richer than
atmospheric air, the yield of oxygen is increased, substantially as herein described.
3. In an apparatus for the production of oxygen gas, the combination of cock
and by-pass adapted to be opened at, and kept open for, the proper time, as and for
the purpose set forth.
4. In an apparatus for the production of oxygen gas, the combination consisting
of retorts, of cocks or valves admitting alternately air and steam to the retorts and
allowing nitrogen gas and oxygen gas to pass out, and of apparatus automatically
reversing the positions of these cocks or valves from time to time, substantially as
herein described.
5. In an apparatus for the production of oxygen gas, the combination consisting
of retorts, of cocks or valves admitting to them steam and air alternately and
drawing off nitrogen and oxygen gases, of another cock or valve drawing off the
impure or dilute oxygen at first produced, and automatic apparatus controlling all
these cocks or valves, substantially as herein described.
6. In an apparatus for the production of oxygen gas, the combination consisting
of retorts arranged in two sets or series; of cocks or valves admitting alternately
air and steam to these retorts and allowing nitrogen gas and oxygen gas to pass
out and apparatus automatically controlling all these cocks or valves so that
whilst air is admitted to the retorts of one series, steam is admitted to the retorts
of the other series, and whilst nitrogen is drawn off from one set of retorts, oxygen
is drawn off from the other set; the whole being so arranged that the apparatus
automatically reverses the positions of all these cocks or valves at suitable times,
substantially as herein described.
7. Apparatus substantially as described and represented by the annexed
drawings.
Dated this 9th day of December 1890.
PHILLIPS & LEIGH,
No. 22, Southampton Buildings, Chancery Lane,
Agents for the Applicant.