AN IMPROVED METHOD OF AND APPARATUS FOR THE COMPLETE PURIFICATION OF COAL GAS BY CONCENTRATED LIQUID AMMONIA, AND THE RECOVERY OF SULPHUR AND AMMONIA FOR THE MANU- FACTURE OF SULPHURIC ACID AND SULPHATE OF AMMONIA
Year: 1878

page_text: LETTERS PATENT to John Hammond, of Lewes, in the County of Sussex,
Gas Engineer, for the Invention of "AN IMPROVED METHOD OF AND APPARATUS
FOR THE COMPLETE PURIFICATION OF COAL GAS BY CONCENTRATED LIQUID
AMMONIA, AND THE RECOVERY OF SULPHUR AND AMMONIA FOR THE MANU-
FACTURE OF SULPHURIC ACID AND SULPHATE OF AMMONIA."
PROVISIONAL SPECIFICATION left by the said John Hammond at the Office
of the Commissioners of Patents on the 14th June 1878.
JOHN HAMMOND, of Lewes, in the County of Sussex, Gas Engineer. "AN
IMPROVED METHOD OF AND APPARATUS FOR THE COMPLETE PURIFICATION OF COAL
GAS BY CONCENTRATED LIQUID AMMONIA, AND THE RECOVERY OF SULPHUR AND
AMMONIA FOR THE MANUFACTURE OF SULPHURIC ACID AND SULPHATE OF AMMONIA."
The object of this Invention is to complete the purification of coal gas by means
of the strong liquid ammonia (produced as described in the Specification filed with
a former application for Letters Patent, namely, No. 3817, dated 15th Oct. 1877), and
to recover the sulphur and ammonia for the purpose of manufacture of sulphate of
ammonia.
To carry out this Invention the strong liquid ammonia, having become fully
impregnated with the impurities from the crude gas (by passing through what is
termed the scrubber washer, vide Specification, No. 3817, Oct. 15th, 1877), the
liquor is received in a large iron tank underground, and closely sealed to prevent
loss of ammonia, the contents of this tank is kept in continuous circulation by
means of pumps connected with large, high, closed iron tanks placed above ground.
These high tanks are so arranged that the liquor of the greatest specific gravity
may be retained for the purpose of manufacture of sulphate of ammonia or concen-
tration and distillation of strong liquid ammonia, as described in Specification
No. 3817, Oct. 15th, 1877. The overflow liquor from the said high tanks, after

page_text: OD.
passing through a series of pipes immersed in running cold water to regulate its
temperature, returns to pumping tanks, and is then forced by means of pumps
through a series of strong cast-iron towers or vessels, for the purpose of being con-
tinuously purified from carbonic acid and sulphuretted hydrogen before being
brought into close contact with the gas. These towers or vessels are so constructed
and arranged as to form distinct chambers for the cold liquor entering the towers,
and for the purified liquor passing on to the purifying vessels, to be described further
Distinct chambers are also provided in the said towers for steam to heat to a
suitable temperature the liquor passing through tubes in the chamber, and for the
gasses escaping from the heated liquor. A vacuum is also produced in the gas
chamber by means of a suitable pump, kept continuously working at a suitable
speed, and connected to the same power driving the liquor pumps.
The said gas
chamber is also filled to a proper height with small pebbles, pumice-stone, coke, or
other suitable material, and the heated gas liquor made to splash over it, and in
descending through it is met by a small measured stream of purified gas admitted
to the lower part of this chamber for the purpose of assisting to remove the foul
gases from the descending liquor. These gases are then pumped away, and forced
through suitable iron boilers or vessels containing milk of lime and strong gas liquor
for the removal of carbonic acid, and through leaden vessels containing sulphuric
acid to recover any small amount of ammonia. The gasses escaping from the closed
leaden vessel may be conducted to a suitable furnace and assist in the direct forma-
tion of sulphuric acid in suitable chambers, or passed through oxide of iron to
recover the sulphur, and the small stream of gas sent back through the hydraulic
main.
The vessels containing the milk of lime can be changed as often as necessary,
being provided in duplicate, and so arranged that heat can be applied and the con-
tents distilled off as described in a former Specification before mentioned. A small
quantity of the hot purified liquid ammonia from the towers is conducted to the
extreme end of hydraulic main, and being met by a jet of steam is forced through
a suitable nozzle in the form of vapour of ammonia, and passing each dip pipe from
which the crude gas is escaping, it raises the temperature of the gas, and passing
onward to the outlet of the hydraulic main, slowly condenses with the gas, and
absorbs therefrom a portion of its impurity.
To prevent the escape of condensible vapours from the outlet of condenser, a
vessel is provided and fitted on the inside with a large number of pieces of thin
hoop iron, so arranged as to break up the gasses into the thinest possible streams.
The speed of the gas through this apparatus is regulated by the height of water
line and overflow pipe, the water also serving as a self-acting by-pass in case
of need.
The purified liquid ammonia when made cold by passing through suitable cooling
pipes in the towers is conducted direct to a series of vessels for purifying the coal
gas from carbonic acid and sulphuretted hydrogen. These vessels may be con-
structed as described in the former Specification before mentioned, and termed the
scrubber washer, or in square-built iron towers, fitted on the inside with layers of
thin hoop iron, placed at a suitable distance to give the best effect to the passing
gas to recover the ammonia. Clean water is used in ordinary coke scrubbers.
Excess of watery vapour or moisture in the gas can be absorbed by passing the gas
through a small amount of quicklime placed in the ordinary purifiers, or by other
suitable means. After using the liquid ammonia to purify the gas as described, it
can be returned to the circulating tank before mentioned, and the process repeated.
When the strong liquid ammonia becomes weak through using excess of water to
recover the ammonia from the coal gas, the liquor can be redistilled, as described in
the former Specification before mentioned. The residual water and carbonate of
lime left in the boilers can be run off by suitable means.
The aforesaid purifying towers for the liquid ammonia are strongly bolted
together with elastic joints, rings of leaden pipe, with the air closely sealed in them,
and the whole covered with the best red rubber. These are capable of resisting

page_text: great pressure, and also allow for expansion and contraction of metal under uneven
temperature.
A modification of the above purifying towers will be found very useful to prepare
crude gas liquor for the ordinary scrubbers or washers in works where it is not
desired to purify the gas entirely by concentrated liquid ammonia, exhaust or live
steam may be used to heat the gas liquor passing through the towers.
condensed hot water may be used as a hot feed for the steam boiler.
The
For the purpose of examining the work of each purifying vessel, a small syphon
well is provided, having a suitable outlet for the liquid from each scrubber or washer
and vent pipes to the closed tanks. This well is fitted with a movable glass cover,
and sealed with a water lute to prevent loss of ammonia.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said John Hammond in the Great Seal Patent Office on the 13th
December 1878.
JOHN HAMMOND, of Lewes, in the County of Sussex, Gas Engineer.
"An
IMPROVED METHOD OF AND APPARATUS FOR THE COMPLETE PURIFICATION OF Coal
GAS BY CONCENTRATED LIQUID AMMONIA, AND THE RECOVERY OF SULPHUR AND
AMMONIA FOR THE MANUFACTURE OF SULPHURIC ACID AND SULPHATE OF AMMONIA."
The object of this Invention is to complete the purification of coal gas by means
of the strong liquid ammonia (produced as described in the Specification filed with
a former application for Letters Patent, namely, No. 3817, dated 15 October 1877),
and to recover the sulphur and ammonia for the purpose of manufacture of sulphate
of ammonia.
The ammoniacal liquor produced in gas-making always contains more or less of
gaseous impurities, and is not used directly to purify the gas, but is stored in tanks
for the purpose of producing therefrom a concentrated purifying liquid, a strong
ammonia water. This ammonia water, having been once brought into contact with
the crude gas, becomes more or less saturated with impurities, and the problem of
its successful utilization for purifying purposes resolves itself therefore into an
economic continuous and successful method of expelling the impurities, leaving the
ammonia in a suitable condition to absorb fresh quantities of carbonic acid and
sulphuretted hydrogen, and the chief value of this Invention consists in providing
suitable apparatus whereby a constant stream of strong alkali ammonia is produced
and distributed in such a manner that it is capable of dealing with all the ordinary
impurities of coal gas as efficiently as the materials more generally used for purify-
ing purposes. The expelled sulphuretted hydrogen is converted into sulphuric acid
by a simple and direct method, and the surplus ammonia can be recovered at
pleasure as sulphate of ammonia.
To carry out this Invention, the strong liquid ammonia having become fully
impregnated with the impurities from the crude gas, the liquor is received in a large

page_text: iron tank underground, and closely sealed to prevent loss of ammonia. The con-
tents of this tank is kept in continuous circulation by means of pumps connected
with large, high, closed tanks above ground. These tanks are BO arranged
that the liquor of the greatest specific gravity may be retained for the purpose of
manufacture of sulphate of ammonia or concentration and distillation of strong
liquid ammonia, as described in Specification No. 3817, Oct. 15, 1877. The over-
flow liquor from the said high tanks, after passing through a series of pipes sur-
rounded by running cold water in a suitable apparatus to regulate its temperature,
returns to pumping tanks, and is then forced by means of pumps through a series of
strong cast-iron towers or vessels, for the purpose of being continuously purified from
carbonic acid and sulphuretted hydrogen before being brought into close contact
with the gas. These towers or vessels are so constructed and arranged as to form
distinct chambers for the cold liquor entering the towers and for the purified liquor
passing on to the purifying vessels, to be described further on. Distinct chambers
are also provided in the said towers for steam to heat to a suitable temperature the
liquor passing through tubes in the chamber, and for the gases escaping from the
heated liquor. A vacuum is also produced in the gas chamber by means of water-
jet arrangement, as shewn in the Drawings, Fig. 1. The said gas chamber is also
filled to a proper height with coke or other material, and the heated gas
liquor made to splash over it, and in descending through it is met by a small
measured stream of coal gas, admitted to the lower part of this chamber for the
purpose of assisting to remove the foul gases from the descending liquor. These
gases are then drawn away and forced through suitable iron boilers or vessels con-
taining milk of lime, and from thence they pass away to a suitable furnace, and
assist in the direct formation of sulphuric acid in suitable chambers.
The vessels containing the milk of lime can be changed as often as necessary,
being provided in duplicate, and so arranged that heat can be applied and the con-
tents distilled off, as described in a former Specification before mentioned. A sinall
quantity of the hot purified liquid ammonia from the towers is conducted to the
extreme end of hydraulic main, and being net by a jet of steam is forced through a
suitable nozzle in the form of vapour of ammonia, and passing each dip pipe from
which the crude gas escaping, it raises the temperature of the gas, and passing
onward to the outlet of the hydraulic main, slowly condenses with the gas, and
absorbs therefrom a portion of its impurity.
To prevent the escape of condensible vapours from the outlet of condenser a
vessel is provided and fitted on the inside with a large number of pieces of thin
hoop iron so arranged as to break up the gases into the thinnest possible streams.
The speed of the gas through this apparatus is regulated by the height of water
line and overflow pipe, the water also serving as a self-acting by-pass in case
of need.
The purified liquid ammonia, when made cold by passing through suitable cooling
pipes in the towers, is conducted direct to a series of vessels for purifying the coal
gas from carbonic acid and sulphuretted hydrogen. These vessels may be con-
structed as described in the former Specification before mentioned, and termed the
scrubber washer, or in square-built iron towers fitted on the inside with layers of
thin plate or hoop iron placed at a suitable distance to give the best effect to the
passing gas. To recover the ammonia clean water is used in ordinary coke scrubbers.
Excess of watery vapour or moisture in the gas can be absorbed by passing the gas
through a small amount of quicklime placed in the ordinary purifiers, or by other
suitable means. After using the liquid ammonia to purify the gas as described, it
can be returned to the circulating tank before mentioned, and the process repeated.
When the strong liquid ammonia becomes weak through using excess of water to
recover the ammonia from the coal gas the liquor can be redistilled, as described in
the former Specification before mentioned. The residual water and carbonate of
lime left in the boilers can be run off by suitable means.
The aforesaid purifying towers for the liquid ammonia are strongly bolted
together with elastic joints, rings of leaden pipe, with the air closely sealed in them,

page_text: and the whole covered with the best red rubber. These are capable of resisting
great pressure, and also allow for expansion and contraction of metal under uneven
temperature.
A modification of the above purifying towers will be found very useful to prepare
crude gas liquor for the ordinary scrubbers or washers in works where it is not
desired to purify the gas entirely by concentrated liquid ammonia. Exhaust or live
steam may be used to heat the gas liquor passing through the towers. The con-
densed hot water may be used as a hot feed for the steam boiler.
For the purpose of examining the work of each purifying vessel a small syphon
well is provided, leaving a suitable outlet for the liquid from each scrubber or
washer, and vent pipes to the closed tanks. This well is fitted with a movable
glass cover, and sealed with a water lute to prevent loss of ammonia. Suitable
thermometer, hydrometers, and other necessary indicators are also fixed in connec-
tion with liquor-purifying towers to guide in its proper working.
DESCRIPTION OF THE DRAWINGS.
Fig. 1 is a sectional elevation of the cylindrical purifying towers for liquid
ammonia. A is the inlet for the cold liquid ammonia which enters the chamber B,
and there deposits any sediment or tarry matter. The liquid then flows up through
the tubes in the chamber U and S to C, and flows out by pipe D, D, to top cistern E.
It then passes down the pipe to cocks G and F, but only a limited quantity is
allowed to trickle through cock F. H is a water-jet arrangement to draw and drive
the gases from chambers F¹, F1, and E¹ to J, and out by the exit pipe A' to the
distilling boilers or the acid towers. The falling liquor may in part descend through
the chamber J, and may be met by a measured stream of coal gas pumped through
pipe B¹ to assist in carrying off the impurities from the liquor. The liquor passes on
through pipe L, L, to chambers M at bottom of second column, the pipe K being a
clearing pipe to distilling boilers. The liquor then rises up through the tubes in
chamber to chamber N, which is kept hot by means of the coil and the exhaust
steam from engine. The foul gases separate from the liquor in this chamber, and
rise up and away through chambers F¹, F¹. The hot purified liquor now passes out
at pipe O, O, and flows into chamber Q, out at pipe R, and into chambers S and U,
and comes out cold at V, and then away to the coal gas purifying vessels or
scrubbers. P is the pipe to supply the hot purified liquor for the hydraulic main.
X is the vent pipe for exhaust steam, which enters the coil by the pipe W; Y is the
hot feed water pipe to steam boiler; C¹ and D¹ are inlets for live steam to clear the
chambers of deposits and to mix with the gases rising in chamber F¹, F'.
Figure 2 shows part sectional elevation of the square-built iron scrubber fitted
with water-jet arrangement to bring the purified liquor into close contact with coal
gas, and at the same time to draw and drive the coal gas up through layers of thin
sheet metal or hoop iron to meet the falling liquor a second time.
Fig. 3 is a part sectional elevation of scrubber washer, and Fig. 4 is plan of rings
of metal in the interior.
Fig. 5 is a plan of bell or cap that covers the entrance pipe to make coal gas pass
through the liquid.
Figs. 6 and 7 shows the plan and elevation of the apparatus for extracting tarry
matter at the outlet of ordinary gasworks condenser, it being very important to
free the coal gas of these matters before bringing it into contact with the cold
purifying liquid ammonia in the scrubbers and washers.
Fig. 8 is part sectional elevation of iron towers or chambers lined with lead
for the direct manufacture of sulphuric acid in connection with the foregoing
apparatus.
A is the arrangement for mixing and burning the gases from
towers; B is the inlet for the sulphurous gases; C, inlet for
water for evaporation in towers F; E is the steam supply for
gases to chambers G, where it condenses in the form of acid;
the liquor-purifying
coal gas; D supplies
mixing and driving
the chamber may be

page_text: filled with coke or other suitable material; J is the outlet for waste gases to flue;
H is the cock to draw off the acid to lead tank I.
Having thus fully set forth my Invention, and the manner in which the same is
to be carried out, I wish it to be understood that I claim,-
First. The improvements substantially as set forth in the use of high closed tanks
and continuous circulation, separation, and refrigeration of the strong liquid
ammonia used in direct purification of coal gas.
Second. The improvements substantially as set forth in the use of an automatic appa-
ratus so constructed and arranged as to deprive a stream of foul liquid ammonia of its
gaseous impurities, and produce a strong alkali ammonia while it is being forced or
pumped through the apparatus direct to the scrubbers, washers, or special apparatus
for the purpose of purifying crude coal gas from sulphuretted hydrogen and carbonic
acid. I also claim to so arrange the mechanical details of this apparatus to suit the
requirements and circumstances of different gasworks, and make it specially applic-
able for the production of either caustic liquid ammonia, strong crude carbonate of
ammonium, sulphide of ammonium, or a combined gas of sulphuretted hydrogen
and carbonate of ammonium for the production of sulphuric acid, and the use of
this apparatus in places other than gasworks to work up gas liquor in the form of
sulphate of ammonia or any of the above products.
Third. The improvements substantially as set forth by the use of steam jet and
nozzle for the use of hot caustic ammonia liquid, and its distribution by steam in
the hydraulic mains of the gasworks.
Fourth. The improvements substantially as set forth in the use of apparatus to
extract the tarry and condensible matters at the outlet of the ordinary gasworks
condenser, Figs. 6 and 7.
Fifth. The improvements substantially as set forth and shewn in Figs. 2, 3, 4, and 5,
and termed scrubber washers, but I do not confine myself to use one kind of appa-
ratus in which to bring the purified liquor into close contact with the coal gas, but
may make use of any ordinary or patent washers or scrubbers that may be in use
on the different gasworks, and according to circumstances.
Sixth. The improvements substantially as set forth in the use of elastic joints of
leaden pipe covered with the best red rubber, and the use of ordinary large size cast-
iron flange pipes or special castings for the manufacture or construction of the said
purifying towers for liquid ammonia and sulphuric acid.
Seventh. The improvements substantially as set forth in the use of apparatus for
the direct manufacture of sulphuric acid (Fig. 8) from the gases derived from the
liquid ammonia towers (Fig. 1).
In witness whereof, I, the said John Hammond, have hereunto set my hand
and seal, this Tenth day of December, in the year of our Lord One thousand
eight hundred and seventy-eight.
JOHN HAMMOND. (L.S.)