Improvements relating to the Drying of Lighting Gas, and to: Apparatus therefor.
Year: 1894

page_text: Date of Application, 12th May, 1894
Complete Specification Left, 12th Feb., 1895-Accepted, 16th Mar., 1895
PROVISIONAL SPECIFICATION.
Improvements relating to the Drying of Lighting Gas, and to:
Apparatus therefor.
I, Dr. JULIUS BUEB, Chemist, of the Deutsche Continental Gas-Gesellschaft,
of 1 Friedrichstrasse, Dessau, in the Empire of Germany, do hereby declare the
nature of this invention to be as follows:-
My invention relates to the drying of lighting gas and to apparatus therefor.
According to this invention I dry the lighting gas, for the purpose of obviating
the closing of the gas pipes by freezing, by means of liquid sulphuric acid which
is maintained within definite limits of concentration, in order that, while drying
the gas, a reduction in the lighting power by the acid may be avoided.
Lighting gas is at present often and in Germany almost generally manufactured
by the dry distillation of coal. Owing to the mode of its production such gas is
saturated with water, that is to say it contains, according to its temperature, a
larger or smaller quantity of water in the form of steam. If such a gas containing
or saturated with water is subsequently cooled to a temperature lower than the
temperature of manufacture a separation of the water takes place. In winter
during frosty weather this water is separated, not in the liquid form, but as white
frost or solid ice crystals which adhere to the inner periphery of the gas pipe and
close the latter in a short time.
The closing of the pipes by freezing on cold winter days is one of the most
familiar and unpleasant occurrences in lighting. The remedy of this inconvenience
by thawing the pipes with spirit or the like occasions considerable outlay.
The water-absorbing power of sulphuric acid renders the latter suitable for
many drying purposes including the drying of gases. However, for drying lighting
gas the use of concentrated sulphuric acid, as already proposed, has heretofore
been deemed inexpedient, as in contact with lighting gas or in the passage of such
gas through the sulphuric acid the latter withdraws not only water but also heavy
hydrocarbons so that a considerable loss of lighting power is experienced in that
case.
Numerous experiments have shown that it is nevertheless possible to advan-
tageously use sulphuric acid for drying lighting gas and yet obviate a diminution
in the lighting power, if the sulphuric acid does not exceed a certain degree of
concentration. This condition has however not been recognized in the use, as
formerly proposed, of sawdust or other porous materials soaked with sulphuric
acid, and it has not therefore been taken into account. On this fact is based iny
aforesaid invention, the characteristic feature of which lies in the employment of
sulphuric acid having a certain degree of concentration.
Sulphuric acid generally possesses such a property at a specific gravity not
exceeding about 1-691. If ise be made of an acid of higher specific gravity the
lighting power of the gas will not only be reduced, but a resinous body will le
separated in the purifier, which in a short time gives rise to clogging and consequently
to disturbances in the working.
In order that the sulphuric acid may also have a drying effect it should not be
below a certain concentration; such a concentration corresponds in general to a
specific gravity of the acid of about 1·615.

page_text: The drying is advantageously effected by the current of lighting gas to be dried
being brought in as fine a division as possible and with little loss of pressure in
contact with the sulphuric acid so often that acid will be properly utilized and that
the gas will be sufficiently dried. Thus the lighting gas may be caused to pass
through scrubbers filled with pieces of broken glass or other material capable of
resisting the action of sulphuric acid, and by means of which the latter is caused
to drop in a finely divided state.
In the experiments made for the purposes of this invention I have found it
advantageous to employ an apparatus arranged on the column system, which may
be found preferable to the scrubber system. The sulphuric acid flows through
this apparatus from above, while the gas to be dried passes through the apparatus
in the opposite direction. By leaden caps provided in each cell the gas is compelled
to pass in a finely divided state through a stratum of sulphuric acid, and by putting
on more cells the gas may be washed by sulphuric acid a greater number of times,
being washed once in each cell. In this apparatus, which may be named a washer,
the gas to be dried passes into a leaden cap furnished in the lower cell of the
apparatus and dipping into the nearly spent sulphuric acid which flows in from the
upper cell through an overflow pipe. In order that the current of gas may pass at
not too great a velocity and in as fine jets as possible through the sulphuric acid,
the leaden cup is made star-shaped and has its immersed lower edge provided with
notches.
After the gas has passed from this cap through the sulphuric acid into the lower
cell proper it is conducted through a pipe into a second leaden cap arranged in the
cell above, which receives through an inlet the sulphuric acid necessary for the
operation. The dried gas passes through a second pipe into the upper cell wherein
a distributing plate may be arranged above the said pipe in order to retain any
liquid which may have been carried away, and thence leaves the apparatus through
an outlet. The several cells are preferably lined with lead and connected with each
other by flanges; they possess moreover small openings through which access is
gained to their interior. The spent sulphuric acid which has become too dilute by
the reception of water leaves the lowest cell through an outlet forming an overflow
pipe, and may be concentrated for further use.
When employing an acid of the before-mentioned concentration I am enabled to
remove with 1 kilogramme about 220 grammes of water from the lighting gas. As
according to extensive experiments about 7 grammes of water must be withdrawn
in winter from each cubic meter of gas in order to protect the same from freezing,
it is possible to dry about 30 cubic metres of gas with 1 kilogramme of sulphuric
acid having a specific gravity of about 1.691.
As moreover spent acid may be easily concentrated for further use the cost of
drying is insignificant, especially when compared with the advantages gained
.thereby.
..
It is however of the greatest importance for the entire method and the practical
working of the same that with the described employment of liquid sulphuric acid
the before-stated limits of concentration are easily controllable at any time during
the operation by measuring the specific gravity, which is not feasible when using
sulphuric acid mixed with saw-dust or the like. If in the present method it is
found, by taking a sample, that the sulphuric acid runs off considerably above the
before-stated minimum concentration the admission of the acid may simply be
interrupted or retarded.
A further important improvement in my method consists in that the operation is
continuous, whereas the drying of the gas by porous materials soaked with
sulphuric acid necessitates periodical interruptions after the manner of the operation
of purifiers.

page_text: Improvements relating to the Drying of Lighting Gas, and to
Apparatus therefor.
I, Dr. JULIUS BUEB, Chemist, of the Deutsche Continental Gas-Gesellschaft,
of 1 Friedrichstrasse, Dessau, in the Empire of Germany, 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 relates to the drying of lighting gas and to apparatus therefor.
According to this invention I dry the lighting gas, for the purpose of obviating
the closing of the gas pipes owing to freezing by means of liquid sulphuric acid
which is maintained within definite limits of concentration, in order that while
drying the gas, a reduction in the lighting power by the acid may be avoided.
Lighting gas is at present often, and in Germany almost generally, manufactured
by the dry distillation of coal. Owing to the mode of its production such gas is
saturated with water, that is to say it contains, according to its temperature, a
larger or smaller definite quantity of water in the form of steam. If such a gas
containing or saturated with water is subsequently cooled to a temperature lower
than the temperature of manufacture a separation of the water takes place: In
winter during frosty weather this water is separated, not in the liquid form, but as
white frost or solid ice crystals which adhere to the inner periphery of the gas pipe
and close the latter in a short time.
The closing of the pipes by freezing on cold winter days, is one of the most
familiar and unpleasant occurrences in lighting. The remedy of this inconvenience
by thawing the pipes with spirit or the like occasions considerable outlay.
The water-absorbing power of sulphuric acid renders the latter suitable for
many drying purposes including the drying of gases. However, for drying lighting
gas the use of concentrated sulphuric acid, as already proposed, has heretofore been
deemed inexpedient, as in contact with lighting gas or in the passage of such gas
through the sulphuric acid the latter withdraws not only water but also heavy
hydrocarbons so that a considerable loss of lighting power is experienced in this
case.
Numerous experiments have shown that it is nevertheless possible to advan-
tageously use sulphuric acid for drying lighting gas and yet obviate a diminution
in the lighting power, if the sulphuric acid does not exceed a certain degree of
concentration. This condition has however not been recognized in. the use, as
formerly proposed, of saw-dust or other porous materials soaked with sulphuric
acid, and it has not therefore been taken into account.
On this fact is based my aforesaid invention, the characteristic feature of which
lies in the employment of sulphuric acid having a certain degree of concentration.
Sulphuric acid generally possesses such a property at a specific gravity not
exceeding about 1.691. If use be made of an acid of higher specific gravity the
lighting power of the gas will not only be reduced, but a resinous body will be
separated in the purifier, which in a short time gives rise to clogging and
consequently to disturbance in the working.
In order that the sulphuric acid may also have a drying effect it should not
be below a certain concentration, such a concentration corresponds in general to a
specific gravity of the acid of about 1.615.
The drying is advantageously effected by the current of lighting gas to be dried
being brought in as fine a division as possible and with little loss of pressure in

page_text: contact with the sulphuric acid so often that the acid will be properly utilized and
that the gas will be sufficiently dried. Thus the lighting gas may be caused to
pass through scrubbers filled with pieces of broken glass or other material capable
of resisting the action of sulphuric acid, and by means of which the latter is caused
to drop in a finely divided state.
In the experiments made for the purposes of this invention I have found it
advantageous to employ an apparatus arranged on the column system, which may
be found preferable to the scrubber system.
I have represented this apparatus in the accompanying drawing, in which
Figure 1 is a longitudinal section on the line A-B of Figure 2;
Figure 2 is a transverse section on the line C-D of Figure 1; and
Figure 3 shows a side view of part of the apparatus.
As shown, the sulphuric acid flows through this apparatus from above, while the
gas to be dried passes through the apparatus in the opposite direction. By leaden
caps provided in each cell the gas is compelled to pass in a finely divided state
through a stratum of sulphuric acid, and by putting on more cells the gas may be
washed by sulphuric acid a greater number of times, being washed once in
each cell.
e.
:
In this apparatus, which may be named a washer, the gas to be dried passes at a
into a leaden cap b furnished in the lower cell d of the apparatus and dipping into the
nearly spent sulphuric acid which flows in from the upper cell d' through an over-
flow pipe
In order that the current of gas may pass at not too great a velocity
and in as fiue jets as possible through the sulphuric acid, the leaden cap b is made
star-shaped and has its immersed lower edge provided with notches c. After the
gas bas passed from the cap b through the sulphuric acid into the lower cell
proper dit is conducted through the pipe a into the leaden cap 6, arranged in the
cell above, which receives through an inlet the sulphuric acid necessary for
the operation. The dried gas passes through the pipe a into the upper cell g
wherein a distributing plate may be arranged above the said pipe in order to
retain any liquid which may have been carried away, and thence leaves the
apparatus through the outlet 1. The several cells are preferably lined with lead
and connected with each other by flanges; they possess moreover openings fitted
with covers fff" through which access is gained to their interior. The spent
sulphuric acid which has become too dilute by the reception of water leaves the
lowest cell through the outlet k forming an overflow pipe, and may be concentrated
for further use.
h
When employing an acid of the before-mentioned concentration I am enabled to
remove with 1 kilogramme about 220 grammes of water from the lighting gas. As
according to extensive experiments about 7 grammes of water must be withdrawn
in winter from each cubic metre of gas in order to protect the same from freezing,
it is possible to dry about 30 cubic metres of gas with 1 kilogramme of sulphuric
acid having a specific gravity of about 1-691.
As moreover spent acid may be easily concentrated for further use the cost of
drying is insignificant, especially when compared with the advantages gained
thereby.
It is however of the greatest importance for the entire method and the practical
working of the same that with the described employment of liquid sulphuric acid
the before-stated limits of concentration are easily controllable at any time during
the operation by measuring the specific gravity, which is not feasible when using
sulphuric acid mixed with sawdust or the like. If in the present method it is
found by taking a sample, that the sulphuric acid runs off considerably above the
before-stated minimum concentration the admission of the acid may simply be
interrupted or retarded.
A further important improvement in my method consists in that the operation is
continuous, whereas the drying of the gas by porous materials soaked with
sulphuric acid necessitates periodical interruptions after the manner of the
operation of purifiers.

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 :-
A method of drying lighting-gas, in which liquid sulphuric acid is employed as.
a drying agent, the specific gravity of the said acid being not higher than
about 1691 and not lower than about 1.615, that is to say not so high to
appreciably injure the lighting power of the gas, but high enough to allow of an
appreciable reception of water to take place, substantially as herein set forth.
Dated this 12th day of February 1895.
.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.