IMPROVEMENTS IN THE MANUFACTURE OF COAL GAS, AND IN THE TREATMENT OF AMMONIACAL LIQUOR OBTAINED IN SUCH MANUFACTURE.
Year: 1877

page_text: LETTERS PATENT to Frederic John Evans, of Brentford, in the County of
Middlesex, and William Thomas Sugg, of Vincent Street, in the City of
Westminster, for the Invention of "IMPROVEMENTS IN THE MANUFACTURE
OF COAL GAS, AND IN THE TREATMENT OF AMMONIACAL LIQUOR OBTAINED
IN SUCH MANUFACTURE.'
"
Sealed the 19th February 1878, and dated the 12th September 1877.
PROVISIONAL SPECIFICATION left by the said Frederick John Evans and
William Thomas Sugg at the Office of the Commissioners of Patents on the
12th September 1877.
FREDERIC JOHN EVANS, of Brentford, in the County of Middlesex, and WILLIAM
THOMAS SUGG, of Vincent Street, in the City of Westminster. "IMPROVEMENTS IN
THE MANUFACTURE OF COAL GAS, AND IN THE TREATMENT OF AMMONIACAL
LIQUOR OBTAINED IN SUCH MANUFACTURE."
The chief object of this Invention is to effect the complete removal of the sulphur
compounds contained in coal gas as it leaves the retorts, and thereby to increase the
illuminating power of the gas. In attaining this object we propose to utilize the
ammoniacal liquor produced in the distillation of coal, and employ the ammonia
derived therefrom as a purifier of the gas.
The removal of the sulphuretted hydrogen from the gas is, as is well known, a
comparatively simple matter, but the removal of the bisulphide of carbon has
hitherto been the great difficulty with gas engineers.
In applying our Invention to an established works, we jacket for a portion of
their length the pipes leading from the several retorts to the hydraulic main, or the
pipe into which the gases generated in the several retorts are discharged, and this
jacketing we extend, if thought desirable, beyond the hydraulic main in order to
maintain the gas at a high heat until its purification is completed. Into the
hydraulic main or its equivalent pipe or chamber we admit ammonia, either in the
form of vapour or as a spray, in such quantity that the carbonic acid and the
sulphur compounds (sulphuretted hydrogen and bisulphide of carbon contained in

page_text: the hot gas) will, as the gas passes into or through the main to the scrubbers, become
neutralized.
The manner of obtaining the ammoniacal vapour is as follows:-The gas liquor
produced in the manufacture of coal gas we run into a boiler, and by the application
of heat thereto drive off the ammonia compounds. These compounds, together with
the steam generated, we lead to vessels such as are used for the purification of gas,
and containing oxide of iron and lime. The oxide of iron will absorb the
sulphuretted hydrogen, as in the ordinary process of gas purification, and the lime,
the carbonic acid, and ammonia thus purified we discharge into the hydraulic main,
adjusting the discharge to the amount of gas which is passing from the retorts.
When sufficient ammonia is presented to the gas to neutralize the acid compounds,
the gas will be deprived of the carbonic acid, sulphuretted hydrogen, and the bisul-
phide of carbon, and when it has passed through the scrubbers it will be fit for use.
It however may be desirable, in some cases, to pass the gas through an oxide of iron
purifier, in case the neutralization of the sulphur acids is not complete.
When liquid ammonia is employed instead of the vapour for purifying the gas, we
pass the ammonia vapour as it leaves the oxide of iron purifier into a condenser,
where it is converted into a strong liquid solution of caustic ammonia, together with
some carbonate. This liquid can easily be deprived of its carbonic acid by treating
it with cream of lime, whereby the whole of the carbonic acid is abstracted, and
nothing remains but a strong solution of caustic ammonia, with some gaseous products
which can be easily removed by a subsequent distillation if required, but for use as
a gas purifier the resulting ammoniacal solution can be used either with or without
the removal of the carbonic acid. This process can be carried out easily as above
stated, but it may be desirable to superheat the steam and ammonia vapours on
leaving the boiler and before entering the vessels containing the oxide of iron. The
advantage of this superheating will be to keep the oxide of iron dry, or nearly so,
by which its chemical action is greatly facilitated.
We may here remark that by the introduction of atmospheric air with the steam
and ammonia vapours, the revivification of the oxide of iron will proceed in the
purifying vessel. The oxide of iron can, as is well understood, be used over and
over again by exposing it from time to time to the external air or by blowing warm
air through it. This oxide of iron can, when it is sufficiently saturated with sulphur,
be used for the making of sulphuric acid in the manner now practised.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Frederick John Evans and William Thomas Sugg in the Great Seal
Patent Office on the 12th March 1878.
FREDERICK JOHN EVANS, of Brentford, in the County of Middlesex, and WILLIAM
THOMAS SUGG, of Vincent Street, in the City of Westminster. "IMPROVEMENTS IN
THE MANUFACTURE OF COAL GAS, AND IN THE TREATMENT OF AMMONIACAL
LIQUOR OBTAINED IN SUCH MANUFACTURE."
The chief object of this Invention is to effect the complete removal of the sulphur
compounds contained in coal gas as it leaves the retorts, and thereby to increase the
illuminating power of the gas. In attaining this object we propose to utilize the
ammoniacal liquor produced in the distillation of coal, and employ the ammonia
derived therefrom as a purifier of the gas.
The removal of the sulphuretted hydrogen from the gas is, as is well known, a
comparatively simple matter, but the removal of the bisulphide of carbon or fixed
sulphur compounds has hitherto been the great difficulty with gas engineers.
In applying our Invention to an established works, we propose to jacket, if neces-
sary, for the whole or a portion of their length the pipes leading from the several
retorts to the hydraulic main, or the pipe into which the gases generated in the
several retorts are discharged, the object being to maintain the gas at a temperature
of some two hundred degrees on its delivery to the hydraulic main. Into the
hydraulic main or its equivalent pipe or chamber we admit ammonia, either in the
form of vapour or liquid, in such quantity that the carbonic acid and the sulphur
compounds (sulphuretted hydrogen and bisulphide of carbon contained in the hot
gas) will, as the gas is subjected to a washing process, become neutralized.
The manner of obtaining the ammoniacal vapour and solution is as follows:-The
gas liquor produced in the manufacture of coal gas we run into a boiler, and by the
application of heat thereto drive off the ammonia compounds. These compounds,
together with the steam generated, we lead to vessels such as are used for the
purification of gas.
One arrangement of apparatus employed for this purpose is shown in the diagram,
Fig. 1, Sheet I. of the Drawings, where A is the boiler for distilling off the ammonia,
and a a pipe leading from the boiler to the first purifier B. This purifier is supplied
with oxide of iron, and it is connected by a pipe b with the second purifier C,
containing lime. The pipe c leads from this purifier to the first of a series of closed
condensing vessels D, which are partly filled with water. These vessels are connected
together by dip pipes & which conduct the surplus ammonia from one vessel to the
other. The ammonia, as it enters the first vessel, is taken up by the water contained
therein, and when the water is saturated the ammonia passes off to the second vessel,
and so on to the whole series, saturating in turn the water supplied to the several
vessels. A pipe leading from the last closed vessel dips into water contained in an
open vessel, and when an escape of ammoniacal gas from this vessel is observed, the
liquor from the condensers is drawn off, and a fresh supply of water is admitted to
the condensers. The oxide of iron in the purifier B will absorb the sulphuretted
hydrogen carried over with the ammonia, and the lime in the purifier C will absorb
the carbonic acid. The ammonia thus obtained will be in the form of a strong
caustic solution, and is then ready for use in the hydraulic main. The supply of
this solution we adjust to suit the amount of gas which is passing from the retorta.
When sufficient ammonia is presented to the gas to neutralize the acid compounds,
the gas will be deprived of the carbonic acid, sulphuretted hydrogen, and the bisul-
phide of carbon, or fixed sulphur compounds contained therein.
When employing ainmonia in the state of vapour, we connect the lime purifier
with the hydraulic main or its equivalent, and thereby bring the ammonia into direct
contact with the hot gas.
The apparatus which we prefer to employ in effecting the purification of the gas

page_text: according to our Invention, is that which forms the subject of an application for a
Patent filed by one of us on the Eighth of January, One thousand eight hundred
and seventy-eight, and illustrated in the accompanying Drawings.
Fig. 2, Sheet II, shows in longitudinal section one of a series of through retorts A,
fitted at its opposite ends with ascension pipes B that lead to hydraulic mains C as
commonly used in gas works. These mains are connected by pipes D, D, with a
vessel E into which the tar deposited by the gas in its passage through the hydraulic
mains is discharged, instead of being allowed to accumulate as at present in the
mains.
In connection with each of these hydraulic mains is an apparatus such as that
shown in longitudinal sectional elevation at Fig. 3, Sheet I., for subjecting the gas
while in a heated state to the action of ammonia.
In this Figure, B represents the dip of one of the ascension pipes, and C the end
of the hydraulic main into which the hot gas from the retorts is conducted; F is an
inclined chamber, divided by partitions into compartments 1, 2, and 3, which
compartments communicate with each other and with the hydraulic main by means
of dip pipes g. These pipes are sealed by liquid ammonia, which is supplied thereto
by a pipe h entering the compartment 3, the same being derived from the pumping
apparatus described with reference to Fig. 1. The compartments also connect with
each other by openings in the partitions f, near the floor of the chamber, and each
compartment is fitted with an overflow plate i, which plates keep the liquor to the
required level in the several compartments, and allow of the descent of the liquor
as the supply is continued from the highest compartment to the lowest, and thence
to the hydraulic main, from which it is discharged into any suitable receiver.
The gas, as it leaves the retorts, will retain its heat while passing up the pipes B,
by reason of such pipes being clothed with non-conducting material (such as is used
for clothing steam boilers) or otherwise protected from the cooling action of the
atmosphere. The gas will thus enter the main at a temperature of some two
hundred degrees, or in a condition best adapted for the efficient action of the
ammonia thereon. It will then pass from the hydraulic main through the several
compartments of the chamber F, as indicated by the arrows, and in so doing it is
caused to bubble through the ammoniacal liquor contained therein, leaving behind it
the tarry products of the coal, the first discharge being, as before mentioned, into
the vessel E; the second into a chamber 1*, forming an extension of the compart-
ment 1; the third into a chamber 2*, being an extension of the compartment 2;
and the fourth (if any tar still remains in the gas) into the chamber 3* of the com-
partment 3. Thus, no accumulation of tar is allowed to interfere with the free
passage of the gas, and as ammonia is freely supplied to the chambers through which
it has to pass, the removal of the carbonic acid and the sulphur impurities contained
in the gas is ensured. As the liquor becomes saturated with impurities it is run off
from the main, and is replaced by the downflow of purer liquor from the compart-
ments of the chamber F, a supply of pure liquid ammonia to that compartment
being maintained during the process of purification. Connected with the compart-
ment 3 of the chamber is a pipe G which carries off the gas as it is purified, and
conducts it to the scrubbers, where its temperature will be reduced and it will be
rendered fit to enter the gas holder.
It may however be desirable to pass the gas through an oxide of iron purifier, in
case the neutralization of the sulphur acids is not complete.
In practice we have found that in carrying out the purification of gas according
to our Invention, the gas derived from one ton of Newcastle coal will be thoroughly
purified by passing the same while in a heated state through one hundred and
twenty gallons of ammoniacal liquor of the strength of ten ounces of ammonia to
the gallon. The gas on leaving the chamber F should not exceed a temperature of
one hundred degrees Fahrenheit.
Fig. 4 shows in sectional elevation and Fig. 5 in plan view a modification of the
above-described apparatus, adapted for gas works in which no hydraulic main is
used, and adapted also for the employment of ammonia in the form of vapour, or it

page_text: may be in the form of spray. In this instance each ascension pipe B is connected
directly with the chamber F, which is in all respects, except in capacity breadth ways,
similar to that described with reference to Fig. 3. A transverse section of this
chamber is shown at Fig. 6. In this arrangement water is admitted by the pipe h,
and the ammonia is supplied from a pipe H, having branches H which lead
respectively into the compartments 1 and 2 of the chamber F. Thus the gas
becomes commingled with the ammonia before passing into the liquor in the first
compartment, and it is caused to yield up a large proportion of its impurities, after
which its progress through the second and third compartment completes its
purification.
We may remark that we do not limit ourselves to the use of any particular
apparatus for bringing the hot gas into contact with ammoniacal liquor for the
purpose of purifying the same, as the only condition requisite is that there shall be
an ample supply afforded to the gas to ensure the neutralizing of the acid compounds
and the absorption of the same into the liquor.
For the purposes of our Invention we may employ the well-known Livesey washer,
a diagram of which is shown at Fig. 7.
Having now set forth the nature of our Invention of "Improvements in the
Manufacture of Coal Gas, and in the Treatment of Ammoniacal Liquor obtained in
such Manufacture," and explained the manner of carrying the same into effect, we
wish it to be understood that under the above in part recited Letters Patent we
claim,―
First. Subjecting coal gas while in a heated state to the action of pure
ammonia in the gaseous or liquid form, in the manner and for the purpose above
described.
Secondly. Obtaining pure ammonia from gas liquor in the manner above set
forth.
In witness whereof, I, the said William Thomas Sugg, have hereunto set my
hand and seal, the Twelfth day of March, in the year of our Lord One
thousand eight hundred and seventy-eight.
WILLIAM THOMAS SUGG. (L.S.)