IMPROVEMENTS IN APPARATUS USED IN GAS WORKS FOR CLEANSING AND PURIFYING GAS FROM AMMONIA AND OTHER IMPURITIES
Year: 1871

page_text: COMPLETE. SPECIFICATION filed by the said William Thomas Walker
at the Office of the Commissioners of Patents, with his Petition and
Declaration, on the 4th July 1871, pursuant to the 9th Section
of the Patent Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
THOMAS WALKER, of the Firm of C. & W. Walker, of the Midland
Iron Works, Donnington, near Newport, Shropshire, and 8, Finsbury
Circus, London, send greeting.
WHEREAS I am in possession of an Invention for "IMPROVEMENTS
IN APPARATUS USED IN GAS WORKS FOR CLEANSING AND PURIFYING GAS FROM
AMMONIA AND OTHER IMPURITIES," and have petitioned Her Majesty to
grant unto me, my executors, administrators, and assigns, Her Royal
Letters Patent for the same, and have made solemn Declaration that I
am the true and first Inventor thereof.
NOW KNOW YE, that I, the said William Thomas Walker, do hereby
declare that the following Complete Specification, under my hand and
seal, fully describes and ascertains the nature of the said Invention, and
in what manner the same is to be performed, in and by the following

page_text: statement, reference being had to the accompanying Drawings and to
the letters and figures marked thereon, that is to say :-
These improvements refer to the purification of coal gas from ammonia
and other impurities by the apparatus herein-after described and shewn
upon the Drawings.
For the removal of ammonia from coal gas, apparatus called scrubbers,
consisting in most cases of circular vessels charged with coke have
heretofore been used. The unpurified gas entering at the bottom and
passing upwards through the interstices of the coke while water or
ammoniacal liquor is poured down from the top..
Various other methods of bringing coal gas in contact with water or
ammoniacal liquor have been tried, but all have proved more or less
imperfect. The difficulty of entirely cleansing gas from its ammo-
niacal and other impurities, without causing very heavy and destructive
back pressure, has occupied the attention of scientific men for years past.
The effectual spreading of the water or ammoniacal liquor at the top
of the scrubber, so that the gas shall not escape coming into perfect
contact with it has always proved a subject of the utmost difficulty.
The Barker's mill" was found to be a very useful means of spreading
water, but the necessarily small holes in the horizontal arms soon
choke up, sometimes in two or three days only, and thus it soon
became impracticable and unserviceable. The same objection applied
to all tubes having small holes. All means of spreading or distributing
water or ammoniacal liquor have hitherto from various causes universally
more or less failed in accomplishing the object described.
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The first part of this Invention is the new means invented for
effectually spreading the water or ammoniacal liquor to cover or saturate
the entire area of the coke, and from experiments I have made this is
accomplished in a very facile and novel manner.
On reference to the Drawings which shew a circular scrubber about
10 feet dia. and about 20 feet high inside the body, it will be seen
that there is a circular or square vessel fixed upon the top of the
scrubber marked A. Inside this vessel is fixed a capacious water
tumbler marked B which receives the water or ammoniacal liquor from
the service pipe, and when one half or division is full it falls over
and discharges its contents into the vessel A, from whence it rushes
down the pipe marked O, which pipe is scaled in the vessel marked D
to prevent any back escape of gas from the inside of the scrubber.

page_text: This vessel D also supports the perforated dash plate herein-after
described, marked F. This vessel D opens upwards into a larger vessel
marked E, and this enlarged vessel has holes all round its circumference
which are of sufficiently large diameter as will prevent their being
choked or stopped up. At the bottom of the vessel D is attached the
large circular plate of iron or other material which I call a dash plate
marked F, which covers the entire surface of the coke to within a
short distance of the scrubber sides. This circular plate is perforated
all over with holes sufficiently large to prevent their being choked, the
plate inclines downwards to its outer circumference as shewn on the
Drawing.
Now the action of the apparatus is as follows:-The half division
of the water tumbler B having been filled by the water or ammoniacal
liquor, and holding for the sized scrubber shown about 3 cwt. of water
or liquor, tumbles over and discharges the liquor with a rapid rush down
the pipe C, which rapidly fills the enlarged vessel E, discharging the
liquor with considerable force out of the holes in its circumference on
to the dash plate beneath, upon which from the height it descends
with considerable violence, and the dash plate being of thin wrought
iron shakes and trembles like the skin of a drum and breaks up the
water or liquor into minute particles, scattering it in all directions over
the surface of the perforated dash plate and against the sides of the
scrubber, thoroughly breaking up the water and distributing it all over
the area of the coke.
It has also another important action or effect. When the circular
vessel E is about full of water or liquor it is arranged to discharge it
by preference to within about 9 inches of the sides of the scrubber,
breaking up the water and dashing it against the sides and extreme
edge of the coke. As the pressure in the vessel E gradually declines
the streams of water gradually draw inwards towards the middle of the
scrubber, and thus by a natural self-acting process the complete area is
covered by the falling water.
The Invention described also enables any quantity of water or liquor.
to be used, as the tumbler will work at any required speed either very
fast or very slow as the quantity of gas to be purified increases or
diminishes; also by the novel method shewn at G of shifting or removing
the centres of the bearings, it will work discharging its contents in any
required quantity, either, or full, or any other quantity as may

page_text: be required. Clean water may also entirely be used or the ammoniacal
liquor may be worked over and over again until it acquires any required
degree of strength.
Proceeding further with the description it will be noticed that the
water or liquor gradually descends through the coke to the bottom (in
opposition to the gas which is gradually ascending) until it reaches the
bottom of the scrubber.
It will be observed that the bottom of the scrubber is a steep cone
or descent from the centre to the sides, or from the sides to the centre,
thus cither concave or convex as shewn in Figs. 1 & 2. This con-
stitutes a simple but important part of this Invention. For directly
the ammoniacal liquor has passed through the coke, by which time it
has become a strong ammoniacal solution of a highly volatile character,
it at once runs down the sides of the conical bottom clean out of the
scrubber entirely.
In all scrubbers as hitherto made the bottom has been quite flat with
the flanges of the bottom plates projecting upwards from the bottom,
and a considerable quantity of the strong ammoniacal liquor has in
consequence been lying in the bottom of the scrubber.
From observations and experiments I have made I discovered the
extremely prejudicial character of this construction. I have found it
almost impossible to thoroughly purify gas from ammonia from this
cause.
I have already explained the great strength the liquor has attained.
by the time it has reached the bottom of the scrubber. Ammoniacal
gas as is well known in chemistry is exceedingly volatile and diffusive.
It is always very difficult to confine it. I have found that it speedily
releases itself to the extent of 35 to 40 per cent. of its strength in the
bottoms of scrubbers; and thus the action of the scrubbers as heretofore
made has been half neutralized by the rapidly ascending volumes of
ammoniacal gas from the ammoniacal liquor in the bottom of the
scrubber ascending and diffusing upwards through the coke again, thus
constantly spoiling the purification after it has been effected.
I have therefore in order to overcome this difficulty invented the
steep conical bottom shewn upon the Drawing, which causes the liquor
at once to discharge itself into the proper wells or tanks prepared-for
it on the gas works directly it has passed through the coke and reached

page_text: the bottom. This causes the action of the scrubber to be developed and
preserved and to retain its purifying action and power constantly, all
the prejudicial counteracting forces being removed.
I prefer to make the conical bottom of smooth cast-iron plates with
the flanges beneath as I have shewn. But it will be understood that the
principle of my Invention may be applied by inverting the cone from
the sides to the centre or vice versa, see Drawings, Figs. 1 & 2, or by
forming a cone of other materials than of cast iron.
By the method of construction shewn on Fig. 1 I obtain additional
height of the column of coke, which height and capacity is lost when
the bottom of the scrubber is constructed flat as heretofore.
Having thus described the nature and use of my said Invention, I
wish it to be understood that I do not confine myself to the precise
details herein shewn and described, I claim the improved scrubber as
shewn with the combination of improved machinery herein-described
and shewn on the Drawings, for receiving, spreading, and distributing
the water or ammoniacal liquor combined with the smooth conical
bottom described, either concave or convex, or formed of any materials
for rapidly discharging the strong ammoniacal liquor directly it reaches
the bottom.
In witness whereof, I, the said William Thomas Walker, have
hereunto set my hand and scal, this Third day of July in the
year of our Lord 1871.
WILLIAM THOMAS WALKER. (L.S.)
5 Witness,
GEORGE R. DAWNAY,
78, Peckham Park Road,
Peckham,
London.