IMPROVEMENTS IN THE APPARATUSES FOR THE PURIFICATION OF COAL GAS
Year: 1877

page_text: LETTERS PATENT to Carl Pieper, of Dresden and Berlin, for the Invention of
"IMPROVEMENTS IN THE APPARATUSES FOR THE PURIFICATION OF COAL GAS."
A communication from August Kloenne, of Dortmund.
Sealed the 17th May 1878, and dated the 19th November 1877.
PROVISIONAL SPECIFICATION left by the said Carl Pieper at the Office of
the Commissioners of Patents on the 19th November 1877.
CARL PIEPER, of Dresden & Berlin. "IMPROVEMENTS IN THE APPARATUSSES
FOR THE PURIFICATION OF COAL GAS." A communication from August Kloenne, of
Dortmund.
This Invention relates to improvements in the arrangement of the scrubber and
the purifyer used in gasworks for the purification of coal gas, and the object of the
same is to construct these apparatusses in such a manner that the solid materials
which they contain may be extracted and replenished without interruption of the
purifying process, and without loss of gas, so that no change of apparatusses is
required during the regular continuation of the working.
The gravel, coke, or other material through which the gas passes in the scrubber,
or the lime, oxyde of iron, Lamming's compound, &c., used in the purifyer, is placed
on inclined grates or hurdles arranged one above the other. These hurdles are
inclined alternately to the right and the left, so that the material lying on the same
has a tendency to slide down, and their upper end is in close proximity to the cor-
responding wall of the apparatus, whilst the lower end (except the one at the bottom
hurdle) is at some distance from the opposite wall. As the end of the lowest hurdle
an inclined tube provided with a slide valve is attached to the apparatus for the
purpose of discharging the spent material. Supposing the said valve to be closed,
the material will bear against it, thereby being retained on the bottom hurdle. The
substances at the end of the next hurdle partly rest on these at the top of the pre-
ceding one, and partly bear against the wall of the apparatus, and are consequently
also prevented from slipping down whilst the slide valve is closed. The same is the
case with the layers on the other hurdles. As soon however as the slide valve is

page_text: opened the material at the bottom which is spent or otherwise unfit for further use
slides out, whereupon a descent of the layers on all the hurdles takes place, one
immediately after the other, until the valve is closed again.
For the purpose of filling up fresh material a reservoir is provided at the upper
part of the apparatus having a funnel-shaped bottom with a trap door in the centre.
This door is attached by a rod to a lever with counterbalance weight, so that the
door will be closed automatically as soon as the reservoir is emptied. The cover of
the latter may then be removed without material loss of gas for the purpose of filling
the reservoir again.
Instead of discharging the materials at intervals, as described, they may be
extracted by creepers which have a continuous action, an escape of gas being in this
case prevented by letting the discharge pipe dip into water. A similar arrangement
may be applied for filling fresh material into the scrubber, as the feed opening for
the gravel or coke may also be kept closed by hydraulic means.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Carl Pieper in the Great Seal Patent Office on the 17th May 1878.
CARL PIEPER, of Dresden, in the Kingdom of Saxony, Civil Engineer. "IMPROVE-
MENTS IN THE APPARATUSES FOR THE PURIFICATION OF COAL GAS." (A communica-
tion by August Kloenne, of Dortmund, Prussia, Engineer.)
This Invention relates to improvements in the arrangement of the scrubber and
the purifyer as used in gasworks for the purification of coal gas, and the object of
the same is to construct these apparatuses in such a manner that the solid material
which they contain may be extracted and fresh material introduced without inter-
ruption of the scrubbing or tlie purifying process, and without loss of gas, so that
no change of apparatuses is required during the regular continuation of the
working.
On the annexed 2 Sheets of Drawings these improved apparatuses are repre-
sented in different views.
Fig. 1 is a side view; Fig. 2, a vertical section; and Fig. 3, a ground plan of the
scrubber; whilst Figs. 4, 5, & 6 represent modifications of a part of the same.
Fig. 7 is a front view; Fig. 8, a vertical section; and Fig. 9, a horizontal section
of the purifyer.
Figs. 10, 11, & 12 show modified arrangements of the grates or hurdles.
The main features of the improvements in the scrubber and the purifyer are the
same.
The gravel, coke, or other material through which the gas passes in the scrubber,
or the lime, oxyde of iron, Lamming's compound, &c., used in the purifyer, is placed
on inclined grates, hurdles, or sieves H1, H2, H3, &c., Figs. 2, 8, & 9, arranged one
above the other in either of the said apparatuses. The hurdles, &c., are inclined at
a suitable angle alternately to the right and the left, so that the material lying on
them has a tendency to slide down. Their upper end is in close proximity to the

page_text: corresponding wall of the apparatus, whilst the lower end (with the exception of the
end of the bottom hurdle) is at some distance from the opposite wall. At the end
of the lowest hurdle an inclined tube C, Figs. 2 & 8, provided with a slide valve,
is attached to the apparatus for discharging the spent material. Supposing this
valve to be closed, the material will bear against it, thereby being retained on the
hurdle H, Fig. 8. The layer on the next hurdle H³ rests at the end, partly on the
material at the top of the hurdle H°, and partly bears against the wall of the appa-
ratus, and is consequently also prevented from slipping down as long as the slide
valve is closed. The same is the case with the layers on the other hurdles. As soon
however as the slide valve is opened, the material at the bottom which is spent, or
which has otherwise become unfit for further use, slides out, whereupon the layers
on all the hurdles descend, one immediately after the other, until the valve is closed
again.
Instead of discharging the material at intervals by means of the described slide
valve, a creeper or conveyer L, which is kept in slow rotation by machinery, may be
employed in either apparatus. An escape of gas is in this case prevented by letting
the discharge pipe dip into water, as shown by Fig. 8.
For the purpose of filling up fresh material a reservoir E, Figs. 2 and 8, is pro-
vided at the top of the apparatus, having a funnel-shaped bottom G with a valve M
in the centre. This valve is attached by a rod passing through a stuffing box to a
lever with counterbalance weight, so that it will be closed automatically as soon as
the reservoir E is emptied. The cover P of the latter may then be removed without
material loss of gas for the purpose of filling the reservoir again. The valve M may
however be constructed in different ways; it may for instance be made flat, and it
may be attached to a shaft passing through the side walls of the apparatus, and
provided on the outside with a counterbalanced lever. Moreover, two or more valves
may be applied, as shown in Fig. 7.
In the scrubber a conveyor or creeper may be applied for filling fresh material
into the apparatus, similar to the one used for discharging, as the feed opening for
the gravel or coke may be kept closed by hydraulic means.
In the side walls of the apparatus there are a number of doors i, i, for the purpose
of examining the grates, or for regulating their inclination by means of the screws 8,
Fig. 8; also larger openings, which are closed by the covers k, may be provided for
facilitating the introduction and the removal of grates.
In the scrubber, when used for cleansing coal gas for lighting purposes, the gas
coming from the condenser enters the scrubber by the tube A, Fig. 2. The end of
this tube dips into the aminoniacal liquor which collects in the lower part of the
apparatus. The gas being thus forced to pass through the liquor, the latter absorbs
sulphuretted hydrogen, carbonic acid, and naphthaline, and washes out the car-
bonate and sulphate of ammonia, as well as compounds of cyanogene, &c., contained
in the gas, and also retains particles of tar which the gas may have carried over.
For the purpose of keeping the gas for a longer time in contact with the am-
moniacal liquor, and of distributing it within the same, the end of the tube A is
surrounded by several annular chambers N1, N2, N3, Fig. 2, open at the bottom, so
that the gas has to pass underneath the edge of all the partition walls of the
chambers. Into the speaces between the said walls other annular walls may project
from below for making the course of the gas yet more circuitous.
A modification of the arrangement for distributing the gas within the ammoniacal
liquor is shown by Figs. 4 & 5. The same consists of a perforated plate o, through
the centre of which the gas inlet pipe A passes from above. The plate is in this
case, by preference, covered with a layer of gravel or coke for the purpose of
increasing the points of contact between the gas and the liquor.
Instead of a singie perforated plate o two or more such plates may be applied, as
in Fig. 6, and the gas may be distributed by means of several branch pipes A³, A³, A³,
&c., from which a number of smaller pipes conduct the same below the lowest
plate o.
S, Fig. 2, is an overflow pipe, which forms together with the tube S¹ a syphon for the

page_text: purpose of keeping the liquor within the apparatus always at the same level
without allowing any gas to escape. This arrangement may be modified according
to Fig. 5.
After having traversed the ammoniacal liquor the gas passes upward through the
different layers of coke or gravel, which are kept saturated by water, and is thereby
freed from ammonia on the usual principle; but, as in the ordinary arrangement,
the layers of coke or gravel remain at rest. The tar deposited from the gas forms
at last prejudicial obstructions in the interstices between the pieces of coke or the
stones.
According to this Invention, however, the layers of coke or gravel being moved
and stirred, either at intervals or continuously, the formation of obstructions is pre-
vented, and the deposited tar is more or less rubbed off by the friction of the pieces
of coke or the stones among each other, so that the water percolating the layers
may carry it away.
The efficiency of the apparatus is consequently always maintained at the same
point, and neither the extraction of the material which has become unfit for further
use, nor the filling-in of fresh material, causes an interruption of the scrubbing
process.
Through tube h pure water is introduced. A second tube may be attached at any
point between the gas inlet and the gas discharge pipe for the purpose of admitting
a certain quantity of the ammoniacal liquor deposited in the hydraulic main or the
condensers, so as thereby to absorb as much as possible the carbonic acid, the sul-
phuretted hydrogen, &c., of the gas; or two scrubbers may be combined, into
one of which ammoniacal liquor is admitted at the top, and into the other pure
water.
On account of the perfect distribution of the water and the gas in the layers of
coke, the quantity of pure water required for cleansing the gas from ammonia is
not more than 1 cubic foot for 10,000 cubic feet of gas. A very strong ammoniacal
liquor is thus obtained, which is specially adapted for purifying the gas from
sulphuretted hydrogen, carbonic acid, and the different salts mentioned above.
The spaces formed between each grate, and the layers of gravel, &c., on the
next lower grate are, with advantage, filled up by rows of thin boards Q, Q, placed
vertically with spaces between them, and supported by ledges, or in any other
suitable manner; these boards serve to increase the scrubbing surface.
Instead of boards brushwood or other similar material may be used for the same
purpose, but the former are to be preferred.
, k, are doors for cleaning the bottom of the apparatus, and for taking out
gravel which may have fallen through the lowest grate.
As has already been stated, the purifyer represented by Figs. 7, 8, & 9 agrees in
its main features with the scrubber, the difference in design being that there is no
washing apparatus at the bottom, and that no water is admitted, as the purifying
material is applied in its dry state as usual.
As it is of advantage to have means for adapting the incline of the grates to the
nature of the purifying material applied in any particular case, the regulating
screws 8 have been introduced, and the grates are hinged to their upper end. It
may, moreover, be observed that it is to be preferred to give to the lower grates
a greater inclination, so as to cause the purifying material, which becomes damp
during the process, and consequently less permeable for the gas, to lie in a thinner
layer on these grates than near the top where it is dry.
The gas enters the apparatus through tube A, and leaves it at the top by tube B.
The extraction of the spent material at the bottom has in this case a similar
influence as with the scrubber. The material on the grates in constantly stirred,
so that its particles are brought in contact with the gas from all sides. It is, there-
fore, utilized in a more profitable manner, and no obstruction to the passage of the
gas can be formed.
The arrangement of the grates or sieves may be modified in different manners,
both in the scrubber and the purifyer. In the first instance the grates may be

page_text: arranged in pairs, so that two grates H¹, H, Fig. 10, are attached opposite to each
other to the walls of the apparatus, while the next pair H2, H2, forms a saddle in
the middle of the apparatus, the following grates H³, H³, being again arranged in
the same manner as H¹, H', &c.
Secondly. Instead of the two grates H', H', converging towards each other, there
may be four grates forming a funnel or inverted frustrated pyramid K', Fig. 11,
while for the grates H2, H2, an upright pyramid K², consisting of four grates, is
substituted.
If the apparatus has a polygonal casing, these funnels and pyramids will, with
advantage, be made of a corresponding polygonal form; and if the casing is round, it
is of course preferable to apply grates baving a conical shape.
If the spaces between the grates and the layers of material below them are in this
case to be filled out by boards, as shown in Fig. 2, the latter may be bent into
cylindrical shape, and arranged within each other.
For the purpose of facilitating the descent of the material if it should clog
and adhere to the grates, it is advantageous to provide these with a shaking
mechanism, such as shown in Fig. 11, where the cones or pyramids K2, K4, &c., are
attached to a rod U, which can be moved up and down by means of a cam T provided
with suitable shaft and lever, or by any other mechanism answering the same
purpose.
In an analogous manner the plain inclined grates H³, &c., of Figs. 2 & 8, may
be made movable, as represented in Fig. 12 (Sheet 1). The grates, which are shown
in this Figure from the outside, bear with the pivot 7 on the arms m of the rods U,
passing between the grates and the side walls of the apparatus, the rods U being
moved up & down by any suitable mechanism. This arrangement may be varied
in different manners, and the grates may have an oscillating or tilting motion, or
they may be moved bodily up and down.
The water percolating the layers of coke, &c., and the grates having a tendency to
run down along the whole length of the grate bars, it is advisable to provide these
bars either with a number of small ledges or with notches on the sides and the
bottom, so as to cause the water to drip off from many points of the under surface
of the grate, and not only from its lower edge, which would cause an unequal
distribution of the water.
If perforated plates are used instead of grates, the burr on the edge of the holes,
resulting from the punching, answers the same purpose as the said ledges or notches
on the grate bars.
The described scrubber, besides presenting great advantages for cleansing coal gas,
and gases distilled from other materials for lighting purposes, is also particularly
useful for the purification of blast furnace gases from smoke and dust. In this case
however I prefer to introduce the gas at the top, and to let it pass downward
through the layers of gravel or coke, which should be kept thinner than in the first
case, so as to reduce the pressure of the gas as little as possible.
The dust and the particles of soot carried over by the gas will be washed out by
the water, and carried down to the bottom of the apparatus, whence they may be re-
moved through suitable openings. The quantity of water required for this process
being but small, the gas is but slightly cooled by the same.
The advantages of the described arrangement of scrubber and purifyer are the
following:-
Firstly. As the coke or gravel in the scrubber, or the purifying material in the
purifyer, is extracted and replenished without interruption of the cleansing and
purifying process, no change of apparatuses is required during the regular continua-
tion of the working. The number of apparatuses is consequently reduced, & the
complicated center-valves, or combinations of slide valves, are obviated; the whole
arrangement is therefore simpler and cheaper in construction.
Secondly. Less space is required for the apparatuses.
Thirdly. The method of operating is cheaper with regard to manual labour.
Fourthly. The loss of gas, hitherto caused by the necessity of opening the an-

page_text: paratuses for changing the material, and the inconvenience arising therefrom by the
diffusion of gas in the rooms of the factory and the neighbourhood is avoided.
Fifthly. The inconvenience of hydraulic joints is avoided.
Sixthly. The purifying material is utilized more efficiently.
Seventhly. The ammoniacal liquor obtained from the coal gas contains a higher
per-centage of ammonia.
Having thus described the nature and object of my Invention, and the manner in
which the same is or may be put into practice, I claim as my Invention in the said
scrubber and the purifyer for coal gas and other gases,-
1. In combination with a scrubber or purifyer for gas, the inclined grates or
sieves H¹, H2, H³, &c., Figs. 2, 8, & 10, substantially as & for the purpose
described.
2. In combination with a scrubber, a purifyer for gas, the conical or pyramidal
grates or sieves K', K², K³, &c., Fig. 11, substantially as specified & for the
purpose set forth.
3. In combination with the inclined grates or sieves H', H³, H³, &c., or with the
conical or pyramidal grates or sieves K³, K2, K³, &c., of a scrubber or purifyer, the
reservoir E, Figs. 2 & 8, provided at the bottom with the valve or valves M, as
& for the purpose specified.
4. In combination with the inclined grates or sieves H1, H2, H³, &c., or with
the conical or pyramidal grates or sieves K1, K2, K³, &c., of a scrubber or
purifyer, the screw or conveyor L, Fig. 8, substantially as & for the purpose
stated.
5. In a scrubber for coal gas, the annular chambers N1, N2, N³, &c., Fig. 2, in com-
bination with the inlet pipe A, as stated & for the purpose specified.
6. In a scrubber for coal gas, one or more perforated plates o, in combination with
the inlet pipe A, or its branch pipes A¹, A², A³, &c., substantially as and for the
purpose described.
. 7. In a scrubber or purifyer, the movable inclined or pyramidal or conical grates
or sieves, in combination with one or more movable rods U, Figs. 11 and 12, sub-
stantially as described & for the purpose set forth.
8. In a gas scrubber, the boards Q, in combination with the inclined, pyramidal,
or conical grates or sieves, as and for the purpose specified.
•
In witness whereof, I, the said Carl Pieper, have hereunto set my hand
and seal, this Twelfth day of April, in the year of our Lord One thousand
eight hundred and seventy-eight.
CARL PIEPER. (L.S.)