Method of Purifying Gas.
Year: 1899

page_text: Date of Application, 5th Sept., 1899-Accepted, 14th Oct., 1899
Method of Purifying Gas.
I, BYRON EDGAR CHOLLAR, of 411, North 11th Street, in the City of St. Louis
and State of Missouri, one of the United States of North America, do hereby
declare the nature of this invention and in what manner the same is to be per-
formed to be particularly described and ascertained in and by the following
statement reference being had to the drawings hereto annexed and to the
figures and letters marked thereon that is to say:
My invention relates to a system of purifying gas wherein the gas is caused
to flow through the purifying apparatus first in one direction and then in a
reverse direction relative to the first flow, for the purpose of reviving the fouled
portion of purifying material through which the gas first passes in the process
of purification.
In the purification of gas by metallic oxide, the principal impurity sought to
be removed is sulpheretted hydrogen.
The practice commonly in vogue is to pass the gas through beds or layers of
purifying material in purifying boxes in one general direction and in regular
order of sequence.
The prevailing idea in regard to the chemical reactions during the process of
purification is that the sulphur of the sulphuretted hydrogen combines with the
iron of the ferric oxide (which is the form of metallic oxide generally used) result-
ing in the formation of sulphide of iron, a liberating of oxygen from the ferric
oxide, which combines with the hydrogen of the sulphuretted hydrogen to form
water.
After the oxide has become so thoroughly saturated with sulphide as to be no
longer sufficiently active for the purpose intended, it can be taken out of the
boxes and exposed to the atmosphere where by the action of the oxygen on the
sulphide of iron, the iron is converted back into its original form, ferric oxide.
This saturation of the ferric oxide with sulphide and revivification may be
carried on repeatedly.
It has been found that by the admission of a small proportion of oxygen into
the purifiers with the foul gas, the process of revivification can go on in the
purifiers simultaneously with the process of purification, the general reactions
being as follows: the sulphur of the sulphuretted hydrogen attacks the ferric oxide,
reducing it partly to ferrous sulphide and partly to ferrous oxide. When atmos-
pheric air is admitted the air acts merely as a conveyor of oxygen, giving it up
partly to the ferrous sulphide and partly to the ferrous oxide, thereby forming
ferrous and ferric oxide over and over again, liberating sulphur at each change,
which sulphur is deposited in metallic form amongst the purifying material.
is true in fact, that having a
From the foregoing it is evident, and moreover
bed of oxide particularly a deep one with a flow of gas containing sulphuretted
hydrogen and oxygen passing through it, upward for illustration, the lower
section of the bed having received the maximum quantity of sulphuretted hydro-
gen in proportion to the oxygen, will become converted into ferrous oxide and
therefore inert sooner than the portion nearer the top where the proportion of the

page_text: sulphuretted hydrogen relative to the oxygen is materially less than exists at the
period of the initial flow of the gas into the purifying bed.
It is also obvious, as well as true in practice, that if when the oxide at the
bottom has become inert (by reason of its then consisting largely of ferrous oxide)
the flow of crude gas be reversed so as to take a directly contrary course to the
flow just described, the oxide at what was previously the last portion of the
purifying material through which the gas passed, and which had to deal with the
minimum amount of sulphuretted hydrogen in proportion to the oxygen, and
which is then in substantially ferric state, and in such condition that it can
effectually take the place of the previously initially subjected portion of the bed of
purifying material for the purpose of removing the sulphuretted hydrogen; at
such time the oxygen contained in the gas with the minimum proportion of
sulphuretted hydrogen in flowing through will re-oxidize from a ferrous to a ferric
state the portion of the bed of purifying material that was originally the entrance
portion. Thus one portion of the purifying bed may be utilized in carrying out
the purification of gas, while the other is becoming revivified by the action of the
oxygen combining with the original oxide to return the elements contained
thereby to their original component parts for utility on the next reversal of the
flow of gas. Oxygen and air are used indiscriminately. Ozone can also be
used as a conveyor for oxygen.
It will be observed that the reviving is accomplished when there is little or no
sulphuretted hydrogen present. The air acting as a conveyor, gives up oxygen
both to the ferrous sulphide and to the ferrous oxide thereby forming ferric oxide
again. This process is repeated over and over again liberating sulphur at each
change. While oxygen has been specified, it is evident that such oxygen may be
'introduced into the gas in any suitable form or by any suitable conveyor, it being
preferable that atmospherical air be used.
It is, in line with the foregoing, the intention of my invention to carry out a
process wherein I am enabled to revive the purifying material (iron oxide) by
following a plan of reversing the direction of flow of the gas through the purifier
as often as is advisable or necessary in order to change the chemical composition
of the purifying material, whenever it becomes fouled by the gas passing there-
through.
In the drawings I have shown a construction of purifying apparatus in the use
of which my system may be carried out, though I do not limit myself to the
particular form of apparatus shown.
Fig. I is a vertical sectional view through the apparatus constructed in
accordance with my invention, taken on the line I-I, Fig. III.
Fig. II is a vertical sectional view taken on the line II-II, Fig. III.
Fig. III is a top or plan view of the apparatus with a portion of one of the
tanks thereof and the main controlling valves shown in horizontal section.
Fig. IV is an enlarged vertical sectional view of a portion of one of the
purifier tanks and the vertical duct pipe located therein.
Fig. V is a vertical sectional view of one of the main controlling valves of
the piping by which the purifier tanks are connected.
Fig. VI is a cross sectional view taken on line VI-VI, Fig. V.
Fig. VII is a cross sectional view taken on the line VII-VII, Fig. V.
1, 1 designate the purifier tanks, in pair, having beds. of purifying material
(iron oxide), 2, 3 and 2ª, 3ª therein. The beds of purifying material 2, 2ª are
mounted on gridwork 4, 4" and the said beds are surmounted by double layers of
gridwork 5, 5 within which are lateral passageways providing for the flow of
gas therethrough to be delivered therefrom into the beds of purifying material, or
to receive the gas from the purifying material, according to the direction of its
flow. 6, 6 designate vertical pipes located against the walls of the purifier tanks
adapted to convey the gas to be purified to the beds of purifying material, as will
hereinafter appear, or to receive the flow of gas from said beds after it has passed
therethrough. The pipes 6, 6ª communicate with openings 7, 7ª in the tank

page_text: walls, see Fig. II, said openings communicating with pipes to be hereinafter
referred to. 8, 8" designate pipes into either of which the gas to be purified may
enter or through either of which it may be discharged. The pipe 8 is provided
with a valve 9 and has connected to it a pipe 10 containing a valve 11 that leads
to the pipe 8°. The pipe 8 is provided with a valve 12 and has connected to it.
a pipe 13 containing a valve 14, said pipe 13 leading to the pipe 8.
15 designates a main controlling valve into which the pipe 8 communicates
and 16 is a main controlling valve into which the pipe 8 communicates. Com-
munication is provided from the valve 15 with the purifier tanks by pipes 17, 17"
and communication between the valve 16 and the purifier tanks is obtained by
pipes 18, 18 that connect with said tanks at the openings 7, 7a that communicate
with the vertical pipes 6, 6" within the purifier tanks. The main valves 15 and 16
are intended for use in controlling the flow of gas from the pipe 8 or 8" into
either purifier tank first and to the other in sequense.
The valves 15 and 16 are of substantially the same construction and I will
therefore describe in particular only the valve 15, which is shown in detail in
Figs. V to VII inclusive. This valve is divided into four compartments by:
partitions 15 arranged in the housing thereof in the form of a cross shown clearly
in Fig. VII. The compartment 15b communciates with the pipe 8, the com- -
partment 15° communicates with the pipes 17 and 17 and the compartment 15d
communicates with the pipe 16ª that leads to the interior of the main valve 16.
The housing of the valve is surrounded by a cap 19 containing a single wing 20
extending thereacross, see Figs. V and VI. The cap 19 is movably mounted on
the valve housing, thereby allowing for its being turned therein to bring the
wing 20 into line with either portion of the cross partition 15ª and close com-.
munication between any two of the compartments within the valve housing
while affording communication between the remaining two compartments.
Having now described the apparatus, I will now proceed to state the manner
in which the flow of gas therethrough mingled with oxygen is controlled and the
courses in which the flow of gas is directed therethrough.
In the first place assuming, for illustration, the gas to be introduced through
the pipe 8 and it to be desired to direct the-flow of gas through the tank 1 in
first one direction and then in reverse direction without the tank 1 being brought
into use.
In such instance the valve .9 would be closed and cause the gas to
pass directly into the pipe 13. The valve 14 in said pipe 13 is open, the valve 12
in the pipe 8 is closed and the main valve 16 is set as seen in Fig. III. Under
such conditions the gas flows through the pipe 8 into the pipe 13 past the valve 14
into the pipe 8 to the main valve 16 and therethrough to the pipe 18, and into
the tank 1, entering the said tank through the opening 7 and flowing into the
pipe 6. The gas flows from the pipe 6 at both top and bottom thereof and enters
the beds of purifying material 2 and 3 and passes therethrough to the double
layer of gridwork 5 from the space between which it passes into the pipe 17.
and therefrom into the main valve 15, which latter will be so set as to bring
the wing 20 in the cap thereof into line with the other portion of the partition 15°
from that at which it is seen arranged in Fig. III, thereby causing the flow of
gas to pass through the main valve 15 into the pipe 8 and therefrom into the
pipe 10 owing to the valve 9 being closed. The valve 11 in the pipe 10 being
open the gas passes through said pipe to the pipe 8 and is delivered therefrom.
to the point of discharge. Now if it is desired to reverse the flow of gas through
the tank 1 so as to cause it to enter the tank through the pipe 17 and after flowing
upwardly and downwardly through the layers of purifying material discharge
through the pipe 6 into the pipe 18, the valve 14 of the pipe 13 is closed as is
also the valve 11 and the valve 9 is opened to permit the flow of gas from the
pipe 8 directly into the main valve 15. The wing 20 in the cap of said valve
under such conditions would remain in the position just described, viz.: the..
contrary position to that seen in Fig. III, and the gas would then flow into the

page_text: pipe 17 to the passageway in the double gridwork 5 and therefrom in upwardly
and downwardly directions into and through the layers of purifying material,
and then into the pipe 6 from which it would emerge from the tank into the
pipe 18 to the main valve 16 and thence through the pipe 8" to the point of
discharge, the valve 12 being opened to permit the flow of gas past it.
Now if it be desired to cut out the tank 1 and convey gas to the tank 1 and
therethrough, the valves 11 and 14 may be closed and the valve 9 opened to permit.
the passage of gas into the main valve 15 and therefrom to the pipe 17" to and
through the tank 1 into the pipe 18 under which condition the valve 16 being
changed from the position seen in Fig. III, the gas is permitted to escape through
the pipe 8, the valve 12 therein being open. To reverse the flow through the
tank 1 the valves 9 and 12 are closed and the valve 14 is open. The gas would
then flow from the pipe through the pipe 13 into the pipe 8 and the valve 16
being changed from the position in which it is seen set in Fig. III, the gas
would flow first through the pipe 18ª into the tank 1" into the main valve 15 set
as seen in Fig. III, then into the pipe 8 through the pipe 10 and therethrough
past the open valve 11 into the outlet pipe 8.
It will now be assumed that it is desired to introduce the gas into the pipe 8
and direct it through the two tanks in sequense in which instance the valve 9
would be opened and the valve 11 would be closed. The gas would therefore be
caused to pass into the main controlling valve 15 in which the wing 20 would
be arranged as seen in Fig. III, so as to direct the gas toward and into the
pipe 17. The gas would then flow through said pipe 17 in the direction indicated
by the arrow in said pipe in Fig. I and enter the purifier tank 1" through the
opening communicating with said pipe, would flow into the passageway in the
double gridwork 5° and therefrom into the beds 2 and 2 of purifying material
in which it would take an upwardly and downwardly course as indicated by the
arrows, Figs. I and II, after which it would enter the pipe 6 at its upper and
lower ends and flow to the center of said pipe where it would find outlet through
the opening 7 into the pipe 18, thence into the main controlling valve 16,
the wing in the cap of which would be set as seen in Fig. III, thereby causing
the gas to flow into the pipe 16" to the valve 15 at the opposite side of the
wing 20 from that at which it first passed through said valve. The gas would
then flow into the pipe 17 and therethrough as indicated in Fig. I in the same
manner and enter the tank 1ª in the same manner and take the same course
through said tank as that described in connection with the tank 1. In leaving
the tank 1 the gas would flow out through the pipe 8 into the valve 16 at the
opposite side of the cap wing therein from that at which it first passed through
said valve, and thence into the pipe 8" from which it would be conducted to the
gas holder.
Assuming the gas to enter the apparatus through the pipe 8 its flow through
the apparatus would be precisely the reverse of that just described and therefore
the gas would first enter the tank 1 through the pipe 6 and flow upwardly and
downwardly therethrough would enter the beds of purifying material at top and
bottom and flow to the center of the purifier into the gridwork 5, therefrom into
the pipe 18 and continue the reverse direction of flow from that first described,
would pass through the valve 15 and pipe 16ª, the valve 16 and the pipe 18 to
the tank 1 through which it would pass downwardly and upwardly to the center
thereof and then out through the pipe 17" again through the valve 15 to the
pipe 8 for discharge. By manipulating the valve caps 19 so as to alter the
position of the wings 20 therein the flow of gas to either purifier tank first as may
be desired may be controlled.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what
I claim is―
The system of purifying gas consisting in effecting a flow of gas having

page_text: oxygen mingled therewith, through purifying material in one general direction
and then effecting a flow of gas having oxygen mingled therewith through the
same material in a general direction to reverse of the preceding flow; substan-
tially as and for the purpose set forth.
Dated this 5th dow of Cantomban 1900
WHITE & WOODINGTON,
Birkbeck Bank Chambers, Southampton Buildings, London, Agents.