Method for Preventing Gas Conduits from being Stopped by Deposits Caused by Frost.
Year: 1895

page_text: Date of Application, 16th Aug., 1895-Accepted, 21st Sept., 1895
COMPLETE SPECIFICATION.
Method for Preventing Gas Conduits from being Stopped by
Deposits Caused by Frost.
I, Dr. JULIUS BUEB, of Dessau, Germany, Chemist, 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 :-
An extremely troublesome disturbance in gas lighting, in particular in street
lighting, consists in the stopping of the conduits produced in very frosty weather
by the freezing of certain deposits out of the gas which assume the form of fine
ice needles, and which narrow or close the clear cross section of the gas pipes.
One of the oldest means for converting these hoar frost like deposits formed in
the interior of gas pipes into a liquid condition consists in the use of ordinary
spirit. By means of this substance conduits leading, say, to street lamps, are.
thawed, the burners being for this purpose screwed off and spirit poured into the
conduit, which in flowing downward dissolves the frozen material and leads it to
the next water pocket. This method of remedying freezing (but not preventing it)
is tedious, expensive, is only of temporary efficacy, and requires much time.
Efforts to find out an efficacious preservative against freezing have therefore
been made long ago.
Already 60 years ago, attempts have been made in England and in 1844 James
Malam proposed (English Patent No. 10326 of 1844) to prevent the separation of
condensates within the conduit network by submitting the whole quantity of gas to
be delivered to the action of frost while still in the gas works, in large, and if
necessary, artificially cooled condensing vessels, called by him "freezing cylinders"
exposed freely to the external temperature.
This method, based on the supposition that water coming from the manufacture
and contained in the gas in the form of vapour, was the sole cause of the freezing
of the conduits, is not applicable in practice and has indeed never been used,
though laterally it has been proposed anew, although, if correctly carried out, the
final purpose, namely, to prevent freezing in the pipe network may be attained.
The fundamental idea contained in this method, namely, to extract from the
lighting gas already in the gas works the condensable constituents, is found again
in different form in several methods, the authors of which also considered as the
cause of the freezing the water contained in the gas, and attempted to free the gas
from water by using water absorbing chemical agents. There have been proposed
and used as drying means of such a kind spirits, (method of J. Malam), chloride
of calcium (method of Dabrowski), sulphuric acid; the latter for instance in the
German Letters Patent No. 77530.
:
All of these methods are of no practical utility, though, in part at least, they are
quite appropriate for preventing freezing.
In carrying out practically on a large scale the method described in the Specifi-
cation of the German Letters Patent No. 77530 it has been proved, that the
opinion that the water contained in the gas is alone the cause of the freezing up of
the gas conduits, is wrong, as in a severe frost, not only water but also benzol is
crystallized on the cold walls of the pipes. As in the method of dessicating by
freezing cylinders as well as in the drying of the gas by means of spirits, benzol is
also separated, unintentionally, besides water, these methods are no doubt appro-
priate for preventing the closing of the gas pipes by freezing, but this is effected at
the expense of the illuminating power of the gas, benzol being the main light.

page_text: producer of the gas. The illuminating power, which for the most part is brought
to the prescribed degree only by gasifying expensive additional coals or by
carburating with benzol or similar substances, is controlled by the authorities and
the public so strictly, that a method, like that of Malam, where the gas owing to
the contact with liquid spirit in a large area, loses so much benzol (more than
10 grammes per cbm. as shewn by experience) that the illuminating power decreased
about 38 per cent., is, in spite of its efficaciousness, industrially not applicable. On
the other hand the separation of water alone, as it is obtained in the process
described in the German Letters Patent No. 77530, or in the method using chloride
of calcium, is not sufficient to prevent the stopping of the gas pipes by freezing in
a strong frost.
Thus all the methods hitherto proposed or tried having for their final purpose to
prevent the closing of the gas pipes by frost by separating from the gas, while
in the gas works, the condensable constituents, or drying processes, are either
inefficacious, or, when they are efficacious, they are inapplicable owing to the
decrease of the illuminating power of the gas.
According to my present invention I propose to attain the intended purpose, not
by withdrawing from the gas any component part, as heretofore attempted, but by
adding a substance that shall have the effect of lowering the freezing point of the
condensible constituents to such an extent, that they precipitate only in a liquid
condition.
As a suitable means for this purpose ordinary spirit has proved advantageous.
It is added to the gas either at the place of the gas production, preferably behind
the gas holder, or at any other point of the pipe network, and in order to avoid any
decrease of the illuminating or heating value of the gas, the spirit is added in the
form of vapour. This is necessary because although liquid spirit would be absorbed
in part by the gas within the gas conduit, yet on the other hand the liquid would
absorb benzol from the gas. Moreover, by adding the spirit vapour produced
outside the gas conduit, the quantity of the introduced spirit vapour can always be
exactly regulated corresponding to the quantity of gas produced and to the external
temperature, while when liquid spirit is introduced into the gas conduit, the gas
passing through takes up a larger quantity of spirit vapour, the lower is the quantity
of gas delivered at the moment and the higher is the external temperature.
It is necessary that the addition of the spirit vapour is capable of regulation, as
on the one hand there must always be so large a quantity of spirit in the gas, that
the intended effect is attained, and on the other hand only so much must be added
as will remain in the gas in the form of vapour. As an appropriate quantity has
been found grammes of spirit vapour per cubic meter of gas delivered; in the
case of particularly severe frosts a little more may be used.
In practically carrying out the method, a small evaporator of ordinary construction
heated by a steam jacket or by small gas burners, is used, into which the spirit
enters from a reservoir arranged at a higher level through a regulating valve in a
fine jet which is immediately evaporated. The hot spirit vapour is introduced
through a small tube into the main and absorbed by the gas. The illuminating
and heating value of the gas is not prejudicially influenced by the small quantity of
spirit vapour. The desired effect of the added spirit vapour only takes place in
that portion of the gas supply which is exposed to the action of the frost, the other,
ordinarily much larger portion of the gas is burnt without the spirit contained
therein exercising any effect. This is a great advantage of the new method in
comparison with the drying by means of spirit; in the latter method the whole
quantity of gas to be delivered is submitted already in the gas works to the action
of the alcohol, absorbing not only the water but benzol, and thereby reducing the
illuminating power; this is entirely unnecessary, as it is always only a small
portion of the gas that passes to such places of the conduit (in particular street
lamps) which are exposed to frost. When applied according to my invention on
the contrary, the spirit enters into action only where the gas is acted upon by frost.
and at the place where such action takes place, in separating from the gas together

page_text: with the water and benzol and thus preventing the latter from congealing and
consequently the conduits from being stopped by freezing.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
A method for preventing gas conduits from being stopped by freezing, without
reducing the illuminating and heating value of the gas, consisting in producing
spirit vapour in an evaporator outside the gas conduit in a quantity susceptible of
regulation, and in adding the said vapour to the gas through a tube introduced into
the main pipe, substantially as set forth.
od thin 16th
1805
ABEL & IMRAY,
Agents for the Applicant.