Year: 1896

page_text: WILLIAM YOUNG, Chemical Engineer, Priorsford, Peebles, SAMUEL GLOVER, Gas
Engineer, North Road, St. Helens, THOMAS GLOVER, Gas Engineer, Mountjoy,
West Bromwich, do hereby declare the nature of this invention to be as follows:-
This invention relates to the manufacture of Illuminating Gas & it comprises
improved methods or processes, having for their object the remedying of certain
difficulties which have been experienced when coals are carbonized at very high
temperatures, with the view of producing a large volume of gas from a given
weight of Coal.
When coals are carbonized at very high temperatures there is produced a large
volume of gas but a comparatively small quantity of condensable hydrocarbons in
the form of Tar; the large volume of gas being mostly derived from the decomposi-
tion of the hydrocarbon products which would be left as tar on carbonizing the
coal at low temperatures.
The decomposition of the volatile and gaseous products from the coal at very
high temperatures has also the effect of considerably altering their constitution,
for, while lessening the yield of liquid condensable products, the quantity of
crystallizable napthalene, is so largely increased, that there is difficulty experienced
in getting the liquid condensable products to take it up in solution; the con-
sequence being that the gas is liable to carry forward in diffusion Napthalene, which
is subsequently deposited in the Mains & Service pipes & gives much trouble.
The gases produced from coal carbonized at very high temperatures, although
large in volume, have a low illuminating power.
The object of this invention is to overcome these difficulties, and, it consists in
providing and applying a supplementary supply of hydrocarbon fluids, to wash
or otherwise act upon the gases produced from coal at such high temperatures, so
as either to remove the Napthalene or to carburett the gas in such a manner as
will increase the illuminating power & prevent the solid napthalene being deposited.
The supplementary supply of hydrocarbon liquids may be derived from various
sources, dependent upon the treatment to which it is desired to submit the high
temperature coal gases, and also applied in various stages during the process of
manufacture dependent upon the constitution of the hydrocarbon liquid supply.
When the sole object is the removal of the Napthalene, any liquid hydrocarbon,
that has a large solvent power for napthalene vapour may be employed, such as
the distillate of Coal tar, after being first deprived as far as possible of dissolved

page_text: napthalene by cooling & filtration, or the distillates of the tar recovered from
Blast furnace gases or similar cheap hydrocarbon liquids.
These hydrocarbon liquids are applied to the gases, by bringing them into
intimate contact with the gas, in any convenient form of Washer or Scrubber.
When first brought into contact with the coal gases, the hydrocarbon liquids
will not only dissolve out of the gas the Napthalene, but also part of the hydro-
carbon illuminants, or if volatile hydrocarbons be present in the washing hydro-
carbon liquids, these may be partially volatalized and 'diffused through the gas;
but after a time, the washing hydrocarbon liquids either become saturated with.
the illuminants present in the Coal gas, or gives up to the Coal gas such a portion
of the vapours of the volatile hydrocarbons that may be present, as to bring about
a balance of the affinities in those respects, & there after the solvent power, of
the washing liquid hydrocarbons is confined to the dissolving out of the Napthalene,
or the hydrocarbon liquids so employed to wash the gas, may be restricted in their
action to the dissolving out of the gas of the napthalene by being either kept at a
temperature sufficiently high to prevent them absorbing the other illuminants
diffused through the gas or subsequently heated to a temperature, that will cause
them to give up to the gas, any such illuminants that they may have dissolved
out of the gas along with the napthalene and, to isolate from the hydrocarbon
liquids the napthalene dissolved out of the gas, and thus fit them for re-use they are
cooled, which causes the napthalene to crystallize out, when it is separated by
filtration by any of the well known methods.
When the object is to Carburett or increase the illuminating power of the gas
produced at high temperatures whilst at the same time removing the napthalene,
or otherwise preventing its precipitation.
The necessary hydrocarbon liquids are specially produced or prepared for the
purpose by subjecting some hydrocarbonaceous substance to carbonization or crack-
ing up at a very low temperature, in any convenient retorting arrangement, so as
to ensure as large a production as possible of liquid products, containing volatile
hydrocarbons suitable for being diffused through the gas.
The hydrocarbonaceous substance suitable for the production of the washing and
carburetting hydrocarbon liquids, by carbonizing or cracking up at low tempera-
tures, are Coal, Shale, or other similar solid bituminous substances, or liquid
hydrocarbons, which have been produced at low temperatures, such as Blast
furnace, Paraffin, or Petroleum Oils.
The products resulting from the carbonizing or cracking up of those substances
at low temperatures, are brought into intimate contact (either whilst still hot and
in the form of vapour or after being cooled) with the coal gases produced at high
temperatures, after such gases have been cooled & had the condensed tar removed
from them, the volatile products from the cracking up of the hydrocarbonaceous
substances at low temperatures, are thus diffused through the high temperature
coal gas, either causing the Napthalene to remain in diffusion, or otherwise be
absorbed, by the accompanying condensable liquid products.
The condensed liquid products that have been thus once used to treat coal gas
are again subjected to further cracking up at low temperatures, so as to produce
a further supply of liquid hydrocarbons, containing carburetting vapours, and again
fit them for re-use, the process being repeated; and in the event of the napthalene
accumulating in the condensed products so as to interfere with their action, as a
washing agent, they are cooled and the crystalline napthalene filtered out in the
manner previously referred to.
Dated this 10th day of September 1801:

page_text: Improvements in the Manufacture of Illuminating Gas.
We, WILLIAM YOUNG, Chemical Engineer, "Priorsford," Peebles, SAMUEL
GLOVER, Gas Engineer, North Road, St. Helens, and THOMAS GLOVER, Gas En-
gineer, Mountjoy, West Bromwich, 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 the manufacture of illuminating gas, and it comprises
improved methods or processes, having for their object the remedying certain
difficulties which have been experienced when coals are carbonised at very high
temperatures with the view of producing a large volume of gas from a given
weight of coal.
When coals are carbonised at very high temperatures there is produced a largo
volume of gas but a comparatively small quantity of condensible hydrocarbons in
the form of tar, the large volume of gas being mostly derived from the decom-
position of the hydrocarbon products, which would be left as tar on carbonising
the coals at lower temperatures.
The decomposition of the volatile and gascous products from the coal when
carbonised at very high temperatures had also the effect of considerably altering
tlieir constitution, for whilst lessening the yield of liquid products, the percentage
of naphthalene is so largely increased that there is difficulty experienced in getting
the liquid condensible products to take it up in solution during the condensing
process, the consequence 'being that the gas is liable to carry forward in diffusion
a part of the naphthlene, which is subsequently deposited during the distribution
of the gas in the mains and services, more or less closing them up and giving much
trouble in various ways.
The gases produced from the coal carbonised at very high temperatures although
large in volume has a low illuminating power.
The object of this Invention is to overcome those difficulties, and it consists in
providing and applying a supplementary supply of hydrocarbon fluids to wash or
otherwise act upon the gases produced at high temperatures so as either to absorb
and remove the naphthalene ordinarily left in the cooled gas, or to carburette
the gas in such a manner as will increase the illuminating power and prevent the
naphthalene being deposited in the crystalline or solid form."
This supplementary supply of hydrocarbon liquids for the treatment of the
high temperature gas may be derived from various sources dependent upon the
convenience and economy in the supply and the treatment to which it is desired to
submit the high temperature coal gases, and it may also be applied in various
stages during the process of manufacture dependent upon the constitution of the
hydrocarbon supply.
When the sole object is the removal of the naphthalene from the gases produced
at high temperatures, any liquid hydrocarbon that has a large solvent power for
naphthalene vapour may be employed such as the distillates of ordinary coal or oil
gas tars, or the distillate of the tars recovered from blast furnace gases or other
cheap hydrocarbon liquids. When such distillates contain naphthalene in solution
they are cooled to a low temperature which causes the naphthalene to separate
in the crystalline form when it is removed by filtration through any suitable
filtering press. These hydrocarbon liquids so prepared are applied to the treatment
of the high temperature gases by bringing them into intimate contact with such
gases (in a manner similar to that by which water is employed to dissolve the
ammonia out of the gas) in any convenient form of washer or scrubber, after the

page_text: high temperature gases have been cooled and freed as far as possible from the high
temperature tars and naphthalene.
When first brought into contact with the high temperature gases the solvent
hydrocarbon liquids act somewhat differently dependent upon their constitution.
If of a high boiling point they will at first not only dissolve out of the gas the
naphthalene but also a part of the other hydrocarbon illuminants. On the other
hand if the hydrocarbon liquids having a low boiling point be present in the
solvent hydrocarben fluid they will, owing to their high vapour tension, be
partially volatilised and diffused through the gas, whilst the naphthalene, owing to
its comparatively low vapour tension will be absorbed; but whatever may be the
original constitution of the washing hydrocarbon liquids, they after a short time
either become saturated with the illuminants present in the gas, or give up to the
coal gas such a portion of the vapours of the volatile hydrocarbons that may be
present in them as to bring about a balance of the affinities in those respects.
Thereafter the solvent power of the washing liquid is confined to the dissolving
out of the gas of the naphthalene. Or instead of allowing the hydrocarbon liquids
with high boiling points so employed to wash the gas to become saturated by
dissolving the illuminants present in the gas, their solvent power may be restricted
to the dissolving out of the naphthalene by keeping them by means of a steam
coil or other equivalent at a temperature sufficiently high to prevent them absorbing
the illuminants having a high vapour tension, whilst yet low enough to allow them
to absorb the naphthalene with the comparatively low vapour tension; or the
absorbent liquid hydrocarbon may have added to it, prior to it, being brought into
contact with the gas, such a quantity of volatile hydrocarbons as, will limit the
action of the absorbing fluid to the dissolving out of the naphthalene.
On the washing hydrocarbon liquid becoming so charged with naphthalene that
it ceases to be effective in washing the gas it is drawn off from the scrubber-and-
refrigerated, which causes the naphthalene held in solution to crystallise out, when
it is separated by filtration. The washing hydrocarbon liquid is then returned to
the scrubber for re-use.
Should the high temperature gases not have been perfectly cooled or freed from
tarry matters prior to being brought into contact with the washing hydrocarbon
Huids, they become so contaminated with tarry matters that the naphthalene
absorbed from the gas by the washing liquid cannot be separated by simply cooling
and filtration. They require to be subjected to a preliminary distillation to fit
them to undergo the filtering process.
In the case of a gas works where plant exists for the distillation of the ordinary
coal tars, this mode of applying our Invention can be very conveniently carried into
effect by collecting the early part of the distillate of the tar, separating the
naphthalene which may be present in solution by refrigeration and filtration, and
using this distillate so prepared in any convenient scrubbing or washing arrange-
ment to wash the cooled high temperature gases and free them from naphthalene,
whilst at the same time the benzole and the other hydrocarbons are volatised into
the gas, adding to the illuminating power. On the coal tar distillate ceasing to be
effective in scrubbing the gas, it is either run direct to the tar well, or sent back
to the tar sills to undergo distillation and filtration, and may thus be prepared
for re-use.
When the object is to carburette or increase the illuminating power of the gas
produced from coal at high temperatures, whilst at the same time removing the
naphthalene, or otherwise preventing its precipitation in the solid form, the
necessary hydrocarbon liquids are specially produced or prepared for the purpose
by subjecting some hydrocarbonaceous substance to carbonisation or cracking up at
such a low temperature in any convenient retorting arrangement as will ensure the
production of a considerable volume of high quality gas and as large a production as
possible of liquid hydrocarbon products as free from naphthalene as to be suitable
to absorb the naphthalene from the coal gas produced at high temperatures, and
containing volatile hydrocarbons suitable for being diffused through the high

page_text: temperature gas, to add to its illuminating power and prevent any naphthalene
that may escape absorption and accompany the gas from being subsequently
deposited in the solid form.
The hydrocarbonaceous substance suitable for the production of the hydrocarbon
fluids for the washing out of the naphthalene and the carburetting of the coal gas
produced at high temperatures by carbonising or cracking up at low temperatures
are coals, shales or other similar solid bituminous substances or liquid hydrocarbons
that have been produced at low temperatures, such as blast furnace petroleum, or
paraffin oils.
The products resulting from the carbonising or cracking up of those substances
at low temperatures, are brought into intimate contact (either whilst still hot and
in the form of vapour suspended in the accompanying gas, or, after having been
cooled) with the coal gases that have been produced at high temperatures, after.
such gases have been cooled and freed as far as possible of the accompanying tars
and naphthalene. The volatile products from the carbonising or cracking up of
the hydrocarbonaceous substances at low temperatures are thus diffused through
the high temperature coal gas, whilst the low temperature condensed products are
at the same time enabled to absorb the naphthalene; and should a part of the
naphthalene escape absorption and pass away with the gas, it is either held in
diffusion or otherwise prevented from being deposited in the solid form by being.
absorbed and dissolved by the accompanying condensible liquid products.
The condensed liquid products that have been thus once used to treat the coal gas,
if found to contain considerable quantities of low temperature products (paraffins
and olefines) are again subjected to further cracking up at low, but yet increased
temperatures, so as to produce a further supply of liquid hydrocarbons free enough
from naphthalene to enable them to be re-used to absorb that substance from, and
to carburette the high temperature coal gases in the manner just described, the
process being repeated till the quantities of naphthalene accumulating in the con--
densed products (due to the absorption of the naphthalene from the high
temperature gas, or its production during the recarbonising of the liquid products
at the higher temperatures) interfere with their action as washing agents. They.
are then cooled and the crystallised naphthalene filtered out in the manner
previously described.
A convenient method of carrying out this modification of our Invention in
existing works involving little alteration or additions of plant, consists in dividing
the retorts into two sections, a large section for the carbonising of the coal at very:
high temperatures for the production of a large volume of gas, and a smaller.
section of the retorts for the distillation of a part of the same or a higher quality
of coal or shale at a lower temperature to produce gas of a high illuminating power
and a supply. of condensible hydrocarbon products suitable for carburetting the
high temperature gases and of absorbing the naphthalene therefrom. The gases
and products from the coal carbonised at the high temperatures are passed through.
the ordinary condensing plant in the usual manner.
The gases and products coming from the coal or shale carbonised at the low
temperature are conveyed by a separate pipe (preferably kept warm either by
lagging with some non-conducting material, or by means of a steam jacket, or
internal steam pipe) and commingled with the condensed high temperature coal
gases after these gases have been condensed and freed as far as possible from:
tarry matters and naphthalene, at or near the terminal of the ordinary condensers.
In the case of a works where the ordinary condensers are of sufficient capacity
and provided with arrangements for drawing off the condensed products as pre-
cipitated, the low temperature gases and products are admitted into the terminal
end of the condensing arrangement amongst the high temperature gases, and the
latter part of the condenser employed to cool the combined gases; but where such
is not the case, a supplementary condenser or preferably a combined condenser
and washer must be provided for bringing the two gases and low temperature
products into intimate contact.

page_text: The condenser hydrocarbon products left in the condenser or scrubber in which
the high temperature coal gases are treated with the lower temperature products,
are somewhat differently dealt with, dependent upon their constitution, which in
turn is dependent on the character of the coal or shale from which they have been
produced and the temperature. at which they have been carbonised.
When ordinary, bituminous coal or the lower, qualities of cannel or shale are the
materials employed to produce the lower temperature products, the most convenient
method is to carbonise them at such a low temperature as will produce condensible
products, which, whilst containing a low percentage of naphthalene and thereby
enabling them to act as an efficient absorbent of naphthalene, will yet be sufficiently
high to crank up the major part of the paraffins and produce a large percentage
of the olefine and benzole group of hydrocarbons suitable to carburette the gas.
In such a case the condensed lower temperature products are 'allowed to flow
directly to the tar well, as they can without injury be commingled with the ordinary
coal tars.
On the other hand when the higher qualities of cannel or shales are employed to
produce the lower temperature products,, the temperature employed to carbonise in
the low temperature retorts may, with advantage be lower, as higher results are
obtained by subsequently re-carbonising the condensed low temperature liquid.
jiroducts. Besides the tars from such high qualities of cannel and shales are, even
when distilled at high temperatures, so rich in paraffins, as to seriously deteriorate
the quality, of the coal tars when mixed with them. Under such conditions the
condensed low temperature products left from the treating of the high temperature
coal gases are drawn off from the, terminal of the condenser or washer,, separated
and subjected to re-carbonisation by any of the well known methods of decom-
posing liquid hydrocarbons. the resulting wednate haine ed in
The proper temperature to employ in the lower temperature carbonising process
necessary to produce the desired results depends upon the original molecular
structure of each coal cannel or shale, and can only be ascertained by trial with
each individual class of material, the tars being subjected to distillation and tested
for the presence of paraffins and naphthalene by the usual well known methods,
and the temperatures of carbonisation regulated accordingly.
Another method of applying our Invention to prevent the precipitation of
naphthalene in the solid form from coal gases produced at high temperatures, is
to volatilise into such naphthalene charged gas, the vapours of any convenient
hydrocarbon having a solvent affinity for naphthalene, and also having a similar or
approximate vapour tension, in such quantities, that in the event of the naphthalene
charged gas being subsequently subjected to such a low temperature as to cause
the naphthalene to precipitate from the gas there will be simultaneously condensed
such a proportion of liquid hydrocarbons as will dissolve it and hold it in solution.
The liquid hydrocarbons suitable for such a purpose are the portions of the
distillates of coal tars, blast furnace tars, paraffin and some varieties of petroleum
oils whose solvent power for naphthalene is considerable and whose vapour tension
approaches that of naphthalene; and they are volatilised into the naphthalene
charged gas in any convenient carburetting arrangement in which the temperature
and the quantity admitted can be so regulated as to cause the volatilisation of the
requisite quantity of such volatile hydrocarbon to produce the desired result. As
the quantity of volatile hydrocarbons required varies dependent upon their con-
stitution as the quantity of naphthalene in the gas, the necessary quantity
under each circumstance must be ascertained by testing the gas leaving
the carburetter by passing through a tube cooled to a temperature
to cause the precipitation of condensible products. If not sufficiently charged
with the hydrocarbon liquid the naphthalene is deposited in a more or less solid
form. If on the other hand more hydrocarbon liquid has been added than
necessary, the condensed matters will not only be liquid but will have absorbed a

page_text: considerable portion of the illuminating vapour from the gas. The quantity
has to be regulated to avoid either conditions.
Having thus particularly described, our said Invention, and the manner in which
the same may be carried into effect, we wish to state that we make no general
claim to the washing of illuminating gas with liquid hydrocarbons for the purpose
of absorbing the condensible hydrocarbons, nor yet do we claim the carburetting
of coal gas by means of volatile hydrocarbons, as both have been extensively
applied, the first for the recovery of the condensible hydrocarbons present in waste
gases from the distillation of shale for the production of oil, and also for the
recovery of the benzole and other condensible products from the gases purposely
produced from coal; and poor coal gases have been extensively curburetted with
very volatile liquid hydrocarbons having much higher vapour tensions than that
of naphthalene, but what we consider to be novel and original and therefore
claim is:-
1. The manufacture of illuminating gas by carbonising coal at high temperature
and washing or similarly treating the resulting gas with such liquid hydrocarbons
as are adapted to absorb or remove the crystallisable naphthalene present in the
gas substantially as described.
2. The method of carburetting and improving the illuminating power of gas
resulting from carbonisation of coal at high temperature by commingling therewith
after such gas has been cooled and freed from the major part of the tar and
naphthalene, gas produced by carbonising coal cannel or other hydrocarbonaceous
material at such low temperature as will ensure the production of gas of high
quality and of liquid hydrocarbons comparatively free from naphthalene and
adapted to absorb or remove the naphthalene remaining in the high temperature
gas, substantially as described.
3. The method of carburetting gas resulting from carbonisation of coal at high
temperature by volatilising into such gas the vapours of liquid hydrocarbons having
a solvent action on naphthalene and having a similar vapour tension, in order to
absorb or remove the naphthalene in solution and prevent its deposit in solid form
substantially as described.
WALLACE FAIRWEATHER,
Of the Firm of Cruickshank & Fairweather,
Chartered Patent Agents,
62 Saint Vincent Street, Glasgow, Agent for the Applicants.