IM- PROVEMENTS IN THE PURIFICATION OF COAL GAS, AND IN THE PRODUCTION OF ALFALIUM SLS TA DE BEKOYA -n ROD SITAL DHRAST" ALFALIVE SULDWIDES TO BE DEPLOYED FOR SUCH Dues
Year: 1873

page_text: LETTERS PATENT to Robert Hogarth Patterson, of Hammersmith, in
the County of Middlesex, Gentleman, for the Invention of "IM-
PROVEMENTS IN THE PURIFICATION OF COAL GAS, AND IN THE PRODUCTION OF
ALFALIUM SLS TA DE BEKOYA -n ROD SITAL DHRAST"
ALFALIVE SULDWIDES TO BE DEPLOYED FOR SUCH Dues"
PROVISIONAL SPECIFICATION left by the said Robert Hogarth Patterson
at the Office of the Commissioners of Patents, with his Petition,
on the 23rd January 1873.
I, ROBERT HOGARTH PATTERSON, of Hammersmith, in the County of
Middlesex, Gentleman, do hereby declare the nature of my said Inven-
tion for "IMPROVEMENTS IN THE PURIFICATION OF COAL GAS, AND IN THE PRO-
DUCTION OF ALKALINE SULPHIDES TO BE EMPLOYED FOR SUCH PURPOSE," to be as
follows:-
This Invention relates firstly to the production of alkaline sulphides
(to be subsequently employed in the purification of coal gas, cither in
the manner described in my Patent dated 9th March 1872, No. 730,
or otherwise) by decarbonating impure coal gas, that is, gas containing

page_text: carbonic acid and sulphuretted hydrogen, in alkaline washers or scrub-
bers, or in lime purifiers, in sucli manner that while the carbonic acid is
arrested in the said washers, scrubbers, or purifiers, sulphuretted hydrogen
is driven forward, and converts alkaline substances, such as potash or
ammonia, ammoniacal liquor or gas liquor contained in subsequent
vessels into sulphides. I also employ the said process for the purpose of
more highly sulphuretting gas liquor, whether decarbonated or not, so
as to render tho said liquor an efficient material for purifying coal gas
from sulphur contained therein in other forms than that of sulphuretted
Sydrogen.
This Invention relates secondly to a system of purification whereby
the climination of carbonic acid from coal gas is effected by means of
lime and alkalies before the said gas is passed through vessels containing
alkaline sulphides either in a solid or in a fluid form, with a view to
purify the gas from sulphur contained therein in other forms than sul-
phuretted bydrogen.
SPECIFICATION in pursuance of the conditions of the Letters Patent
filed by the said Robert Hogarth Patterson in the Great Seal Patent
Office on the 23rd July 1873.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ROBERT
HOGARTH PATTERSON, of Hammersmith, in the County of Middlesex,
Gentleman, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-third day of January, in the
year of our Lord One thousand eight hundred and seventy-three, in
the 36th year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Robert Hogarth Patterson, Her special
license that I, tho said Robert Hogarth Patterson, my executors,
administrators, and assigns, or such others as I, the said Robert
Hogarth Patterson, my executors, administrators, or assigns, should at
any time agree with, and no others, from time to time and at all times
thereafter during the term therein expressed, should and lawfully
might make, use, exercise, and vend, within the United Kingdom of

page_text: condition (amongst others), that I, the said Robert Hogarth Patterson,
my executors or adminstrators, by an instrument in writing under my
hand and seal, should particularly describe and ascertain the nature of
the said Invention, and in what manner the same was to be performed,
and cause the same to be filed in the Great Seal Patent Office within
six calendar months next and immediately after the date of the said
Letters Patent.
NOW KNOW YE, that I, the said Robert Hogarth Patterson, do hereby
declare the nature of my said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and
by the following statement, that is to say :-
This Invention is as follows :—
I.-(1). Production of Sulphides of Potassium.-A solution of caustic
potash is employed in a washer, scrubber, or other vessel or vessels, into
which impure coal gas is passed after being treated as follows:―The
impure coal gas is passed through vessels hercin called decarbonating
vessels, containing an alkaline substance or substances, such as lime,
soda, potash, ammonia, or the ammoniacal solution called gas liquor, for
such time and in such manner as that the carbonic acid contained in
the impure coal gas shall from its greater affinity for those alkaline
substances have expelled sulphuretted hydrogen (likewise contained in
the impure gas) from the said vessels, taking its place and driving it,
namely, sulphuretted hydrogen, forward with the coal gas into the vessel
or vessels containing the solution of potash, to be sulphuretted, whereby
the said solution is converted into sulphides of potassium. As soon as
the coal gas issuing from the decarbonating vessels contains carbonic
acid the contents of one or more of them are to be changed, and the
vessels recharged with any of the before-mentioned alkaline substances
or mixtures thereof, so as to arrest the carbonic acid, and whenever or
soon after the coal gas issuing from the vessels containing the solution
of potash to be sulphuretted contains sulphuretted hydrogen the process
of producing sulphides of potassium in those vessels is completed.
(2). Production of Sulphides of Ammonium.-The ammoniacal solu-
tion called gas liquor is first decarbonated, that is to say, it is treated
with lime or with other suitable alkaline substances in a manner well

page_text: understood in order to eliminate the carbonic acid contained in the said
gas liquor. Thereafter the liquor, which is now a weakly sulphuretted
solution of ammonia, is employed in a washer or scrubber or other vessel
or vessels, and treated by the process above described relative to tho
production of sulphides of potassium, that is to say, impure coal gas is
passed through vessels herein called decarbonating vessels, containing an
alkaline substance or substances, such as lime, soda, potash, or ammonia
or gas liquor, for such time and in such manner as that the carbonic acid
contained in the impure coal gas shall from its greater affinity for these
alkaline substances have expelled sulphuretted hydrogen (likewise con-
fained in the impure gas) from the said vessels, taking its place and
driving it, namely, sulphuretted hydrogen forward with the coal gas into
the vessel or vessels containing the decarbonated gas liquor, whereby the
said liquor is to the desired extent sulphuretted or converted into sulphides
of ammonium. As soon as the coal gas issuing from the decarbonating
vessels contains carbonic acid, the contents of one or more of them are
to be changed, and the vessels recharged with any of the before-men-
tioned alkaline substances or mixtures of the same, so as to arrest the
carbonic acid, and whenover or soon after the coal gas issuing from the
vessels containing the decarbonated gas liquor to be sulphuretted contains
sulphuretted hydrogen the process of producing sulphides of ammonium
in these vessels is completed.
(3). The Sulphuretting of ordinary Gas Liquor.-Gas liquor in its
ordinary condition is obtained or employed in a washer or scrubber or
other vessel or vessels, and treated in the manner above described relative
to the production of sulphides of potassium and of sulphides of ammo-
nium, that is to say, impure coal gas is passed through vessels herein
called decarbonating vessels, containing an alkaline substance or sub-
stances, such as lime, soda, potash, or ammonia or gas liquor, for such
time and in such manner as that the carbonic acid contained in the
impure coal gas shall from its greater affinity for these alkaline substances
have expelled sulphuretted hydrogen (likewise contained in the impure
gas) from the said vessels, taking its place and driving it, namely, sul-
phuretted hydrogen, forward with the coal gas into the vessel or vessels
containing the gas liquor to be more highly sulphuretted, whereby the
liquor in those vessels is sulphuretted more conveniently and economically
than if sulphur in a solid form were mixed and combined with the said
gas liquor.

page_text: II. Having thus produced the above-named alkaline sulphides, in-
cluding the more highly sulphuretted gas liquor by the process abovo
described, whereby carbonic acid and sulphuretted hydrogen are by one
and the same process eliminated from coal gas, I propose to employ the
said alkaline sulphides, including the more highly sulphuretted gas
liquor for the purpose of purifying coal gas from the sulphur cxisting in
the said gas as bisulphide of carbon or in other forms than that of
sulphuretted hydrogen.
One manner or method I employ is as follows:-After purifying coal
gas from sulphuretted hydrogen by oxide of iron purifiers in the ordinary
manner I pass the said gas through vessels containing lime, or through
washers or scrubbers or other vessels containing a solution of one or
more of the alkaline substances already mentioned, so as to climinate the
carbonic acid, and thereafter I pass the said gas thus decarbonated, and
which has been previously purified from sulphuretted hydrogen, through
a vessel or vessels containing sulphides of potassium or sulphides of
ammonium, including the more highly sulphuretted gas liquor described
in section 1 (3), for the purpose of purifying the said gas from the
sulphur contained therein in the form of bisulphide of carbon, or in
other forms than that of sulphuretted hydrogen. Or the purification of
coal gas first from carbonic acid and thereafter from sulphur (i.c., sul-
phuretted hydrogen and the other sulphur compounds) may be more
conveniently and economically effected by the employment of alkaline
washers or scrubbers or other vessels as follows:-A solution of potash
or decarbonated gas liquor, or gas liquor in its ordinary condition, is
employed in a series of washers or scrubbers or other vessels, in the
employment of which vessels I apply the process already described,
whereby the carbonic acid is climinated from the coal gas in the first
vessel or vessels of the series, while the sulphur in the said gas (i.c., sul-
phuretted hydrogen and the other sulphur compounds) is eliminated in
thic subsequent vessels of the series.
For convenience and economy I prefer to employ ordinary gas liquor
for this purpose in the following manner, but the process is the same if a
solution of potash or decarbonated gas liquor be employed, that is to say,
I pass the impure coal gas through a series of vessels in which gas liquor
is formed or obtained in the ordinary process of gas purification (i.e., in
condensers and washers or scrubbers) in the following manner :-The
impure coal gas is passed through the first vessel or vessels of the series

page_text: for such time and in such manner (previously described) as that the
carbonic acid is arrested by the gas liquor, while sulphuretted hydrogen
passing forward with the coal gas is arrested in the subsequent vessels of
the series, converting their contents into sulphides of ammonium, which
is an efficient material for climinating from coal gas the sulphur existing
therein as bisulphide of carbon or in other forms than that of sulphur-
etted hydrogen. In this process I employ the gas liquor in the first
vessel or vessels of the scries for such time and in such manner as that
the carbonic acid contained in the coal gas shall from its greater affinity
for ammonia be absorbed by the gas liquor in those vessels, while the
sulphuretted hydrogen expelled therefrom by the carbonic acid, or
otherwise passing forward with the coal gas, sulphurets or converts into
sulphides of ammonium the liquor contained in the subsequent vessel or
vessels of the series.
The process of working the immediately before-mentioned series of
alkaline washers or scrubbers and other vessels upon the principle or
system herein described will vary to some extent according to the
number of those vessels employed, and also according to the relative
proportions in which ammonia and carbonic acid and sulphuretted
hydrogen exist in the gas which is to be purified. If (as is usually the
case) the quantity of ammonia existing in the coal gas be not sufficient
to absorb the whole of the carbonic acid, and also thereafter to absorb the
sulphuretted hydrogen, in so doing producing sulphides of ammonium
in the latter vessels of the scrics, and if it be necessary or desirable to
increase the quantity or alkaline strength of the liquor employed in the
said series of vessels, I employ decarbonated gas liquor in one or more of
these vessels, that is to say, a portion of the gas liquor which has done
its work, and has thereafter been decarbonated, is employed in addition
to tho gas liquor produced in the ordinary course of gas manufacture or
purification, in order to produce the desired results above mentioned.
Instead of decarbonated gas liquor a solution of caustic soda may be
employed in one or more of the above-mentioned vessels. In this case
it is more economical to employ the soda exclusively in the last vessels
of the series, separate from or with as little admixture of ammonia as is
possible, for the following reason:--Soda not being volatile a solution
of soda employed in the manner above described can be repeatedly rc-
vivified (that is to say) freed from the carbonic acid and the sulphuretted
hydrogen absorbed by it in the above-mentioned process), and thereafter

page_text: be re-employed in the washers or scrubbers or other vessels, whereas
decarbonated gas liquor (owing to the volatile nature of the ammonia
contained therein) cannot be revivified so cconomically.
Note. By the process lastly before described I effect the purification
of coal gas in a manner which I believe to be more economical and not
less efficient than any which has hitherto been proposed, namely, by
employing solely or chiefly substances contained as impurities in the gas
itself. Under the present systom of absorbing ammonia from coal gas
in the condensers and in washers or scrubbers the coal gas issuing from
thoso vessels or from the last of the scries contains a large amount of
carbonic acid and sulphuretted bydrogen, the carbonic acid being in
much larger quantity than the sulphuretted hydrogon; but by turning
to practical account the greater affinity which carbonic acid has for
ammonia than sulphuretted hydrogen has in the manner already
described, and also if necessary by increasing the quantity or alkaline
strength of the liquor contained in the washers or scrubbers or other
vessels by the employment of gas liquor which has been decarbonated,
or a solution of soda, the whole of the carbonic acid can be eliminated
in the first vessel or vessels of the series, while the sulphuretted hydrogen
passing forward is absorbed in the subsequent vessels of the series, at the
same time producing in these latter vessels sulphides of ammonium (or
sulphides of ammonium and of sodium together), which is an efficient
material for purifying the gas from the sulphur existing therein as
bisulphide of carbon or in other forms than that of sulphuretted
hydrogen.
Having now described and particularly ascertained the nature of my
said Invention, and the manner in which the same is or may be used or
carried into effect, I would observe in conclusion that what I consider to
be novel and original and therefore claim as the Invention secured to
me by the herein-before in part recited Letters Patent is,―
Firstly. The application and use of sulphides of potassium and of
sulphides of ammonium produced in the manner herein-before described,
and including also gas liquor, which has been more highly sulphuretted
by the process herein-before described, for the purpose of purifying coal
gas from sulphur existing therein as bisulphide of carbon or in other
forms than that of sulphuretted hydrogen.
Secondly. The employment of lime or of a solution of soda or of limc,
or of potash or ammonia, or gas liquor or mixtures of the same, in the

page_text: manner hercin-before described, in order to produce or obtain sulphides
of potassium, sulphides of ammonium, or the more highly sulphuretted
gas liquor before referred to, and also thereaftor if desired to maintain
them in that condition.
Thirdly. The employment of a series of vessels containing ordinary gas
liquor, and also or together with (if necessary) gas liquor which has been
decarbonated in the manner herein-before described, whereby coal gas
may be economically and efficiently purified from carbonic acid in the
first vessel or vessels of the series, and from sulphuretted hydrogen and
the other sulphur compounds in the subsequent vessels of the scries.
In witness whereof, I, the said Robert Hogarth Patterson, havo
to this my Specification set my hand and seal, the Twenty-first
day of July One thousand eight hundred and seventy-three.
R. H. PATTERSON.
(L.S.)
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