IMPROVEMENTS IN THE METHOD OF PURIFYING GAS, AND IN THE APPARATUS EMPLOYED FOR THAT PURPOSE
Year: 1871

page_text: LETTERS PATENT to William Mann, of the Gas Works, "Dorset
Street, in the City of London, Engineer, for the Invention of
"IMPROVEMENTS IN THE METHOD OF PURIFYING GAS, AND IN THE APPARATUS
EMPLOYED FOR THAT PURPOSE."
'
Sealed the 28th May 1872, and dated the 2nd December 1871.
PROVISIONAL SPECIFICATION left by the said William Mann at the
Office of the Commissioners of Patents, with his Petition, on the
2nd December 1871.
"I, WILLIAM MANN, of the Gas Works, Dorset Street, in the City of
London, Engineer, do hereby declare the nature of the said Invention
for IMPROVEMENTS IN THE METHOD OF PURIFYING, GAS, AND, IN THE APPARATUS.
EMPLOYED FOR THAT PURPOSE," to be as follows:-
اهز
The distillation of coal for the purpose of manufacturing illuminating
gas results in the production not only of gas suitable for giving light,
but of other substances which are regarded as impurities, and which

page_text: require to be removed therefrom before the gas is fit to be consumed.
These impurities consist principally of tar, water, ammonia, and sulphur
both in the form of sulphuretted hydrogen, and as other sulphur com-
pounds, the principal of which is bisulphide of carbon. The method of
removing the tar, water, ammonia, and sulphuretted hydrogen is so well
known as not to need description, but the sulphur compounds other than
sulphuretted hydrogen have baffled all attempts to remove them com-
pletely with any degree of certainty.
My Invention is based upon the chemical fact that the sulphides
of the alkalies and of the alkaline earths combine with bisulphide of
carbon, and in carrying out my Invention I prefer to use the sulphide
of calcium, or the mixture of the sulphide and bisulphide of calcium
produced in purifying gas from sulphuretted hydrogen, and I'find the
following arrangement of apparatus most suitable to my purpose.
TL
Y
In addition to the ordinary purifiers marked A, B, C, and D in the
accompanying Diagram, two, three, or more supplementary purifiers
E, F, G, are provided. These are charged with hydrate of lime and
sufficient gas allowed to pass through one of them, say F, to convert its
contents into, sulphide or, sulphide and bisulphide of calcium. The
quantity of gas to be passed through to effect this conversion may be
determined by previous trial. The crude gas is then shut off from F,
which now contains the sulphide or sulphides of calcium, and is made to
enter G and pass through the hydrate of lime, with which it is furnished.
Here the gas is freed from much of its sulphuretted. hydrogen. It then
passes on to the oxide of iron purifiers D or D and C, where it is purified
from sulphuretted hydrogen, and fitted for entrance to the sulphide of
calcium purifier F. It is presumed that the gas having passed through
hydrate of lime and oxide of iron, has been cleaned from all impurities
except bisulphide of carbon, now free to be acted upon by the sulphide
or sulphides of calcium with which it will combine, but as during this
operation the gas will have become again charged with sulphuretted
hydrogen, it is necessary to convey it into a further oxide of iron
purifier C or B, where the sulphuretted hydrogen will be removed,
leaving the gas practically free from sulphur in any form.
t
3
To continue the routine a step further for the sake of making the
process clear; it may be assumed that the lime in the vessel G has
received enough sulphuretted hydrogen from the known quantity of gas
2

page_text: required to convert it into sulphide or-sulphides of calcium. A change
of valves is then made, which alters the direction of the gas, but while
the order of the vessels is varied the same circuit or order of materials is.
preserved, the gas passing through E (lime), D and C (oxide of iron),
then through G (sulphide of calcium), and afterwards through B (oxide
of iron), always supposing that the lime or oxide contained in these
vessels is capable of performing its proper functions.
While the sulphide or sulphides of calcium in the vessel F is found to
be capable of acting on the gas, the vessel E, in which the sulphide of
calcium is supposed to have become inert by reason of its previous
employment for the abstraction of the bisulphide of carbon, may be
discharged and re-charged with lime, the other vessels in their turn
being emptied and replenished. The apparatus can be worked in any
way most convenient as regards the individual vessels made to form the
circuit, but care must be taken that no more gas be allowed to pass
through the lime than is found by practice to be sufficient to convert it
-into-the-sulphide or sulphides of calcium, and that after passing through
one or more oxide of iron vessels to purify it from sulphuretted hydrogen,
it is to be driven through sulphide of calcium, and then again through
oxide of iron, to free it from all traces of sulphuretted hydrogen.
·
f.
The same principle may be applied by exposing the gas when freed
from sulphuretted hydrogen to the action of sulphide of ammonium con-
tained in the gas liquor as follows:-The four ordinary purifiers H, I, J,
and K, are to be charged with oxide of iron and supplemented by two
or more scrubbers L and M, L receiving strong (say 30 ounce) gas liquor
and M clean water. The gas, after passing through K and J, and
being thereby freed from sulphuretted hydrogen, is conveyed through
scrubber L, where the bisulphide of carbon is acted upon by the sulphide
of ammonium in the same manner as by the sulphide of calcium in the
former arrangement. The gas is. then conducted through the scrubber M,
when any ammonia it may have acquired by passing through the strong
gas liquor is removed by the clean water supplied thereto. Finally, the
gas is led through one of the oxide purifiers I for the purpose of extract-
ing the sulphuretted hydrogen produced by the action of the sulphide of
ammonium in passing the gas through the scrubber L. The principle
to be observed here, as in the former arrangement, being that the gas
shall be, by exposure to lime or oxhide of iron, freed from carbonic acid

page_text: and sulphuretted hydrogen previous to its being brought into contact
with the sulphide of ammonium, and that subsequently it shall again be
passed through oxide of iron, or hydrate of lime.
:
It is not absolutely necessary that the vessels A, B, C, and D, or
H, I, J, and K, should be charged with oxide of iron, but with purifiers
as at present constructed oxide of iron is preferable to lime, as it requires
less pressure to pass the gas through it, in addition to possessing some
other practical advantages. Lime can, however, be used in all the
purifiers just mentioned.
In order to ensure the greatest amount of success that can attend
the use of the foregoing method, I have devised and use in conjunction
with it an improved construction of purifier, to which the inlets and
outlets are so arranged that the gas, instead of going upwards through
all the layers of lime or other purifying agent, is made to traverse half
the number of layers (or thereabouts) upwards, and the other half or
remaining number of layers downwards. And this is accomplished with-
out mechanical agency (although the arrangement admits of its use)
by making the number of layers of purifying material one less in the
lower half, or should the number be equal in each half, by charging the
layers on the lower half a litter lighter than those on the upper half.
The consequence of this is that the gas naturally takes its course through
the lower layers first, and continues to flow in that direction until the
material composing the lower half is nearly saturated, a condition which
always makes the purifying agent less pervious to the gas (especially
where the agent is lime), whereupon the gas will commence flowing
downwards through the upper half of layers until a balance of resistance
is induced by the saturation of these upper layers. Immediately on this
taking place the gas will divide into two currents, one going upwards
and the other downwards, thereby keeping the pressure low, bringing
about a better saturation of the purifying agents, and a more perfect
purification of the gas than would be the case if all the gas was
permitted to pass in the same direction through all the layers of lime or
other material at the same time.
++
!
T

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said William Mann in the Great Seal Patent Office on
the 1st June 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
MANN, of the Gas Works, Dorset Street, in the City of London, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Second day of December, in the
year of our Lord One thousand eight hundred and seventy-one, in the
thirty-fifth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said William, Mann, Her special licence
that I, the said William Mann, my executors, administrators, and
assigns, or such others as I, the said William Mann, my exécutors,
administrators, and assigns, should at any time agree with, and no others,
from time to time and at all times thereafter during the term-therein
expressed, should and lawfully might make, use, exercise, and vend,
within the United Kingdom of Great Britain and Ireland, the Channel
Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN THE METHOD
OF PURIFYING GAS, AND IN THE APPARATUS EMPLOYED FOR THAT PURPOSE," upon
the condition (amongst others) that I, the said William Mann, my
executors or administrators, by an instrument in writing under my, or
their, or one of their hands and seals, should particularly describe and
ascertain the nature of the said Invention, and in what manner the
same was to be performed, and cause the same to be filed in the Great
Seal Patent Office within six calendar months next and immediately after
the date of the said Letters Patent.
NOW KNOW YE, that I, the said William Mann, do hereby declare
the nature of my said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the
following statement, reference being had to the accompanying Drawings,
and to 'the letters and f
'figures marked thereon, that is to say :-
The distillation of coal for the purpose of manufacturing illuminating
gas results in the production not only of gas suitable for giving light;
but of other substances which are regarded as impurities, and which
require to be removed therefrom before the gas is fit to be consumed.

page_text: These impurities consist principally of tar, water, ammonia, and sulphur,
both in the form of sulphuretted hydrogen and as other sulphur
compounds. The method of removing the tar, water, ammonia, and
sulphuretted hydrogen is so well known as not to need description, but
the sulphur compounds other than sulphuretted hydrogen have baffled
all attempts to remove them completely with any degree of certainty.
My Invention is based upon the chemical fact that the sulphides of
the alkalies and of the alkaline earths combine with bisulphide of carbon,
and although they have been applied with this intention before, they
have either been used in an improper state, or when the bisulphide of
carbon contained in the gas has not been in a suitable condition to be
acted upon by them, or the materials employed have not occupied the
proper position in the purifying circuit to effect the object in view. In
carrying out my Invention. I prefer to use the sulphide of calcium, or
the mixture of the sulphide and bisulphide of calcium produced in
purifying gas from sulphuretted hydrogen, and I find the arrangement
of apparatus presently to be described most convenient and suitable to
my purpose.
In order that the foregoing and the description which follows may be
more easily understood, Drawings are attached hereto, of which Fig. 1
represents a sectional elevation of the improved form of purifier, and
Fig. 2 a plan of the same, the cover in both cases being removed.
Fig. 3 exhibits a set of purifiers either of the ordinary kind, or by
preference of the improved construction, arranged so as to suit the
process now to be described, and Fig. 4 is a diagram to illustrate
the process as applied to the combination of a set of purifiers and
scrubbers.
In addition to the ordinary purifiers marked A, B, C, and D, Fig. 3,
in the accompanying Drawing, two, three, or more supplementary
purifiers E, F, G, are provided. These are charged with hydrate of
lime, and for the sake of explaining the process it must be supposed
that sufficient gas has passed through one of them, say F, to have
converted its contents into sulphide or sulphide and bisulphide of
calcium. The quantity of gas to be passed through to effect this con-
version may be determined by previous trial:- The crude gas is then
shut off from F, which now contains the sulphide or sulphides of
calcium, and is made to enter G, and pass through the hydrate of lime

page_text: The same principle, may be applied by exposing the gas when freed
from sulphuretted hydrogen to the action of sulphide of ammonium
contained in the gas liquor as follows: The four ordinary purifiers H, I,
J, and K, Fig. 4, are to be charged with oxide of iron and supplemented
by two or more scrubbers L and M, L receiving strong (say 30 ounces)
gas liquor and M clean water. The gas, after passing through K and J,
and being thereby freed from sulphuretted hydrogen, is conveyed through
scrubber L, where the bisulphide of carbon.is acted upon by the sulphide
of ammonium in the same manner-as-by-the-sulphide of calcium in
the former, arrangement. The gas is thus conducted through the
scrubber M, when any ammonia it may have taken up by passing
through the strong gas liquor is removed by the clean water supplied
thereto. Finally the gas is led through one of the oxide purifiers I for
the purpose of extracting the sulphuretted hydrogen produced by the
action of the sulphide of ammonium in passing the gas through the
scrubber L. The principle to be observed here as in the former arrange-
ment, being, that the gas. shall be by. exposure to lime or oxide of
iron freed from carbonic acid and sulphuretted hydrogen previous to
its being brought into contact with the sulphide of ammonium, and
that subsequently it shall again be passed through oxide of iron or
hydrate of lime.
"It is not absolutely necessary that the vessels A, B, C, and D, or
H, I, J, and K, should be charged with oxide of iron, but with purifiers
as at present constructed oxide of iron is preferable to lime, as it requires
less pressure to pass the gas through it in addition to possessing some
other, practical advantages. Lime can' however be used in all the
purifiers just mentioned.
In order to ensure the greatest amount of success that can attend the
use of the foregoing method,-I-have devised and use in conjunction with
it an improved construction of purifier to which the inlets N, N', and
outlets O, O, are so arranged that the gas, instead of going upwards
through all the layers of lime or other purifying. agent, is made to
traverser half the number of layers-(or-thereabouts)-upwards, and-the-
other half for remaining number of: layers downwards. And this is
accomplished: without mechanical agency, (although the arrangement
admits of its use and will be explained subsequently) by making the
number of layers of purifying material one less in the lower half P,
Fig. 1, or should the number be equal in each half by charging the

page_text: "
layers on the lower half a little lighter than those on the upper lialf.
The consequence of this is that the gas naturally takes its course through
the lower layers P first, and continues to flow in that direction until the
material composing the lower half is nearly saturated, a condition which
always makes the purifying agent less pervious to the gas (especially
where the agent is lime), whereupon the gas will commence flowing
downwards through the upper half of layers Q'until a balance of re-
sistance is induced by the saturation of these upper layers. Immediately'
on this taking place the gas will divide into two currents, one going
upwards through .P and the other downwards through Q, thereby
keeping the pressure low, bringing about a better saturation of, the
purifying agents, and a more perfect purification of the gas than would
be the case if all the gas was permitted to pass in the same direction
through all the layers of lime or other material at the same time.
.
.
The mechanical agency to which I have alluded consists of slide
valves, which are shown at R, R. By means of these valves I can
if necessary regulate the circuit of the gas through the lower or upper
layers by partly or wholly closing one or both, as may be desired. The
slide valves are worked by a screw, a continuation of this screw passing
through a stuffing box in the side of the purifier with a square on the
outside to receive a handle or spanner.
In the plan, Fig. 2, the arrangement shows two inlets N, N, and two
outlets O, O, but if used as a purifier in the ordinary way, and only with
a view of reducing the pressure that is always produced by lime, one
inlet and one outlet only are required.
If the slide valves R, R, are closed the gas on being turned in to such
a purifying vessel will ascend the vertical pipe S and flow downwards
through the upper layers Q, and from thence pass to the outlets O, O,
thus escaping the lower layers P; but when the upper layers are
saturated, the slide valves may be opened, and the gas will then pass
upwards through the lower layers P by virtue of their least resistance.
Having now described and particularly set forth the nature of this
Invention, and the manner in which the same is or may be used or
carried into effect, I would observe in conclusion that I do not confine
or restrict myself to the precise details or arrangements which I have
described or referred to, as variations may be made therefrom without
deviating from the principles or main features of this Invention; but.

page_text: what I consider to be novel and original, and therefore claim as
the Invention secured to me by the herein-before in. part recited
Letters Patent is,―
•
Firstly. For the use of sulphide or sulphides of calcium formed and
used in the order and manner described in this Specification.
.
Secondly. For the use of sulphide of ammonium used in the order and
manner as previously herein described.
>
And, thirdly; For the construction of purifiers, substantially as herein
described, whereby the resistance of the purifying material employed in
them is considerably reduced.
In witness whereof, I, the said William Mann, have hereunto set
my hand and seal, this First day of June, in the year of
One thousand eight hundred and seventy-two.
our Lord
ילדי
Witness to the signature of
the said William Mann,
W. H. BENNETT,
42, Parliament Street,
Westminster.