Improvements in the Manufacture of Chlorine and in the Apparatus used therein.
Year: 1891

page_text: Date of Application, 6th July, 1891
Complete Specification Left, 5th Apr., 1892-Accepted, 7th May, 1892
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Chlorine and in the Apparatus
used therein.
I, THOMAS HUGH BELL, of Middlesbrough, in the County of York, Iron
Master, (a communication to me from abroad by Théophile Schloesing, of
67 Quai d'Orsay, Paris, in the Republic of France,) do hereby declare the nature
of this invention to be as follows :-
My improvements relate to the process of obtaining chlorine from chloride of
magnesium by rendering it.anhydrous as is described in the Specifications filed in
respect of the Letters Patent granted to my communicator dated 31st August 1887
No. 11,821.
According to this invention a retort is employed preferably made of earthenware
such as is used in gas-works. Within this retort a grid or grating is placed
(preferably also of earthenware) running lengthways through the retort and
leaving below it a shallow space. This grid which may be made in one or more
pieces is pierced with slits or holes preferably narrow rectilinear openings. It is
better to make the openings widen as they pass into the interior of the slab so as
to make it substantially a grated earthen hearth covering the whole extent of the
lower wall of the retort. Upon the grid is placed the anhydrous chloride of
magnesium in a uniform bed preferably of a few inches thick. In the retort above
this layer is an open space of some inches in depth. Thus the chloride and the
grid on which it rests are separated from the upper wall and from the lower wall
of the retort by two unoccupied spaces. Openings in the retort communicate with
these spaces and by these openings the upper one communicates with a conduit
through which air is introduced and the lower one with a conduit through which
gas passes out more or less charged with chlorine. The retort and its contents
being brought to a dull red heat the air contained in the interstices in the bed of
chlorine gives up its oxygen to the magnesium and becomes charged with chlorine
and thus a mixture of nitrogen and chlorine is formed which is heavier than air and
consequently passes through the bed of chloride and the grid on which it rests and
descends into the open spice situated below. If then the upper open space receives
a continuous current of air the gas which is charged with chlorine can continuously
flow into the conduit which has been prepared for it. The movement of the gases
through the bed of chloride will thus take place continuously and the chlorine will
be taken off as its conversion is effected from the chloride of magnesium. The
passage of the gas from above downwards across the bed of chloride is found to
take place with great regularity. As the chloride of magnesium is granulated it
is very permeable and does not interfere with the movement of the gas by offering
unequal resistance to it. This movement of gas across the bed of chloride and the
grid on which it rests is regulated by the progressive increase in the weight of the
gas which tends to cause it to become stratified in the order of its densities. This
causes the gases from all parts of the bed to descend with uniform rapidity and the
chloride to be evenly decomposed.
The introduction of the air and consequently the duration of its contact with the
chloride can be regulated so as best to utilize the oxygen and to secure a maximum
proportion of chlorine in the developing gas. Furthermore any desired pressure
(either above or below the pressure of the atmosphere) can be given to the gas in
circulation.
Reference has been made to the use of an earthenware grid to support the
chloride but it is evident that the filtering surface on which the chloride rests can

page_text: be otherwise constructed. The arrangements made in the interior of the retort can
be varied and the retort itself can even be replaced by a muffle or other containing
vessel without departing from the essential conditions of the success of the
operation viz. that a layer of chloride very permeable and of an equal thickness
should be spread on a filtering surface which is itself readily permeable to the
gases. That the air coming into a free space above this layer should traverse it
from above downwards-that the gases containing the chlorine should be easily
drawn off at the outlet of the filtering surface, so that the movement of the gas
should take place in the manner already described and explained.
The movement of the air across the layer of chloride is thus due to a continuous
increase in the density of the gases that is to say to a physical condition and may
be regarded as a general phenomenon dependent on the above causes and
independent otherwise of the nature of the gases and of the matter through which
they pass.
Following the same principle therefore if in the retort furnished with its filtering
grid we replace the anhydrous chloride of magnesium by chloride of magnesium in
grains and the air by steam this steam penetrating into the chloride in grains will
become charged with hydrochloric acid gas in consequence of a well known
reaction. This gas is heavier than steam so that the gaseous mixture will take up
a density increasing in proportion as it advances into the layer and will similarly
run out below the grid and thence into the external pipes. Care must be taken to
regulate the rapidity of the circulation of steam and gases in such a way as to
obtain a maximum of hydrochloric acid in the outgoing gaseous mixture.
Thus by the same arrangements either chlorine can be prepared from anhydrous
chloride of magnesium and air or hydrochloric acid gas from chloride in grains and
steam. In the same way as an increased density causes a downward movement of
the gaseous mixture across the grid so on the other hand a diminution of density
in a gaseous mixture will cause a like movement upwards. If then a layer of
chloride in grains is placed on the grid (the whole being raised to a dull red heat)
and a current of hydrochloric acid gas is introduced into the free space below it
will on penetrating into the layer of chloride become charged with water vapour
and will pass into the free space above the layer and thence into the outer pipes,
causing a dehydration of the chloride in grains.
It results from this that the same apparatus will serve to obtain first the
anhydrous chloride from the chloride in grains and then chlorine from the
anhydrous chloride.
In the above description only one retort has been spoken of but the process may
be carried out in a series of retorts the gas passing successively through more than
one of the members of the series. In this way the process can be worked on the
continuous system the gas passing in succession through retorts in which the
conversion is in progressively advanced stages commencing with a retort in which it
is just beginning and ending with one in which it is on the point of completion. The
retorts and the grids may be horizontal or the one or the other may be inclined.
The arrangement of the retorts may be circular or elliptical or in two or more rows,
the heating arrangements being preferably such that two or more retorts are heated
from the same furnace or the same part of a furnace.
Dated this 6th day of Lul 1201

page_text: COMPLETE SPECIFICATION.
Improvements in the Manufacture of Chlorine and in the Apparatus
used therein.
1, THOMAS HUGH BELL, of Middlesbrough, in the County of York, Iron
Master, (a communication to me from abroad by Théophile Schloesing, of 67 Quai
d'Orsay, Paris, in the Republic of France,) 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 improvements relate to the process of obtaining chlorine from chloride of
magnesium by rendering it anhydrous as is described in the Specifications filed in
respect of the Letters Patent granted to my communicator dated 31st August 1887
No. 11,821.
According to this invention a retort is employed preferably made of earthenware
such as is used in gas works. Within this retort a grid or grating is placed
(preferably also of earthenware) running lengthways through the retort and leaving
below it a shallow space. This grid which may be made in one or more pieces is
pierced with slits or holes preferably narrow rectilinear openings. It is better to
make the openings widen as they pass into the interior of the slab so as to make it
substantially a grated earthen hearth covering the whole extent of the lower wall
of the retort. Upon the grid is placed the anhydrous chloride of magnesium in a
uniform bed preferably of a few inches thick. In the retort above this layer is an
open space of some inches in depth. Thus the chloride and the grid on which it
rests are separated from the upper wall and from the lower wall of the retort by
two unoccupied spaces. Openings in the retort communicate with these spaces and
by these openings the upper one communicates with a conduit through which air
is introduced and the lower one with a conduit through which gas passes out more
or less charged with chlorine. The retort and its contents being brought to a dull
red heat the air contained in the interstices in the bed of chloride of magnesium
gives up its oxygen to the magnesium and becomes charged with chlorine and thus
a mixture of nitrogen and chlorine is formed which is heavier than air and con-
sequently passes through the bed of chloride and the grid on which it rests and
descends into the open space situated below. If then the upper open space receives
a continuous current of air the gas which is charged with chlorine can continuously
flow into the conduit which has been prepared for it. The movement of the gases
through the bed of chloride will thus take place continuously and the chlorine will
be taken off as its conversion is effected from the chloride of magnesium. The
passage of the gas from above downwards across the bed of chloride is found to
take place with great regularity. As the chloride of magnesium is granulated it is
very permeable and does not interfere with the movement of the gas by offering
unequal resistance to it. This movement of gas across the bed of chloride and
the grid on which it rests is regulated by the progressive increase in the weight of
the gas which tends to cause it to become stratified in the order of its densities.
This causes the gases from all parts of the bed to descend with uniform rapidity
and the chloride to be evenly decomposed.
The introduction of the air and consequently the duration of its contact with
the chloride can be regulated so as best to utilize the oxygen and to secure a
maximum proportion of chlorine in the developing gas. Furthermore any desired
pressure (either.above or below the pressure of the atmosphere) can be given to
the gas in circulation.
Reference has been made to the use of an earthenware,grid to support the
chloride but it is evident that the filtering surface on which the chloride rests can
be otherwise constructed. The arrangements made in the interior of the retort can

page_text: be varied and the retort itself can even be replaced by a muffle or other containing
vessel without departing from the essential conditions of the success of the
operation viz. that a layer of chloride very permeable and of an equal thickness
should be spread on a filtering surface which is itself readily permeable to the
gases. That the air coming into a free space above this layer should traverse it
from above downwards that the gases containing the chlorine should be easily
drawn off at the outlet of the filtering surface, so that the movement of the gas
should take place in the manner already described and explained.
As is well known, the density of gases varies as their temperature. It is essential
therefore that the temperature should be, as far as possible, equal in all parts of the
retort, in order that the relations between the densities of the different mixtures of
gases should not be disturbed.
The movement of the air across the layer of chloride is thus due to a continuous
increase in the density of the gases that is to say to a physical condition and may be
regarded as a general phenomenon dependent on the above causes and independent
otherwise of the nature of the gases and of the matter through which they pass.
Following the same principle therefore if in the retort furnished with its filtering
grid I replace the anhydrous chloride of magnesium by chloride of magnesium in
grains and the air by steam this steam penetrating into the chloride in grains will
become charged with hydrochloric acid gas in consequence of a well known reaction.
This gas is heavier than steain so that the gaseous mixture will take up a density
increasing in proportion as it advances into the layer and will similarly run out
below the grid and thence into the external pipes. Care must be taken to regulate
the rapidity of the circulation of steam and gases in such a way as to obtain a
maximum of hydrochloric acid in the outgoing gaseous mixture.
Thus by the same arrangements either chlorine can be prepared from anhydrous
chloride of magnesium and air or hydrochloric acid gas from chloride in grains
and steam. In the same way as an increased density causes a downward movement
of the gaseous mixture across the grid so on the other hand a diminution of density
in a gaseous mixture will cause a like movement upwards. If then a layer of
chloride in grains is placed on the grid (the whole being raised to a dull red heat)
and a current of hydrochloric acid gas is introduced into the free space below it
will on penetrating into the layer of chloride become charged with water vapour
and will pass into the free space above the layer and thence into the outer pipes,
causing a dehydration of the chloride in grains.
It results from this that the same apparatus will serve to obtain first the
anhydrous chloride from the chloride in grains and then chlorine .from the
anhydrous chloride.
in the above description only one retort has been spoken of but the process may
be carried out in a series of retorts the gas passing successively through more than
one of the members of the series. In this way the process can be worked on the
continuous system the gas passing in succession through retorts in which the con-
version is in progressively advanced stages commencing with a retort in which it is
just beginning and ending with one in which it is on the point of completion. The
retorts and the grids may be horizontal or the one or the other may be inclined.
The arrangement of the retorts may be circular or elliptical or in two or more
rows the heating arrangements being preferably such that two or more retorts are
heated from the same furnace or the same part of a furnace.
DESCRIPTION OF THE DRAWINGS.
Figure 1 is a longitudinal section and Figure 2 a transverse section of the retort
fitted with grids.

page_text: 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 production of chlorine by the downward percolation of air into a suitably
heated bed of anhydrous chloride of magnesium and the withdrawal of the chlorine
gas from the bed in a downward direction.
2. The production of hydrochloric acid gas by the downward percolation of
steam into a suitably heated bed of chloride of magnesium in grains, and the
withdrawal of the acid gas from the bed in a downward direction.
3. The production of anhydrous chloride of magnesium from chloride of
magnesium in grains by the upward percolation of hydrochloric acid gas into a
suitably heated bed of chloride of magnesium in grains and the withdrawal of
watery vapour from the bed in an upward direction.
4. Apparatus substantially as described and shown in the drawings.
T. HUGH BELL.