Improvements in the Purification of Carburetted Hydrogen or Coal Gas.
Year: 1888

page_text: Date of Application, 9th May, 1888
Complete Specification Left, 7th Jan., 1889
Complete Specification Accepted, 12th Feb., 18
Improvements in the Purification of Carburetted Hydrogen or
Coal Gas.
We WILLIAM ANDREW MCINTOSH VALON of the Ramsgate Gas Works Civil
Engineer and BRIN'S OXYGEN COMPANY Limited of Connaught Mansions in the
City of Westminster do hereby declare the nature of this Invention to be as
follows:-
This Invention has for its object to effect the purification of carburetted hydrogen
or coal gas in a better or more efficient manner than hitherto with much less space
and plant being necessary to effect the purification and with economy in time and
labour in manipulation.
According to this Invention Oxygen Gas preferably that which is produced by
operating according to Brin's process as described in the Specification of Letters
Patent No. 157 of 1885 is passed into or mixed with the Gas to be purified and the
Oxygen and the Gas are then together passed through purifiers containing caustic
alkali preferably lime.
The proportion of oxygen gas employed will vary according to the amount of
impurities in the Gas but generally for every one hundred grains of sulphur present
in each one hundred cubic feet of the impure Gas one part by volume of the oxygen
gas will be used for every one thousand parts by volume of the gas to be purified.
The reactions which take place are we believe as follows:
The calcium hydrate (supposing for the purpose of this example that lime is the
alkali used) takes up the sulphuretted hydrogen from the impure gas and forms a
sulphide of the alkali used (in this case calcium sulphide) which in its turn acts upon
the sulphur compounds other than sulphuretted hydrogen.
The sulphide and other sulphur derivatives of the alkali (in this case calcium
sulphide &c.) are re oxidized by the oxygen which has been passed into or mixed
with the gas according to this Invention and are in great part re vivified by being
retransformed into the hydrate of the alkali (in this case calcium hydrate) the
sulphur being in great part separated as free sulphur. This hydrate of the alkali (in

page_text: this case calcium hydrate) is also capable of absorbing the carbonic anhydride with
formation of a carbonate of the alkáli employed as in the usual method of purification
by lime.
The aforesaid actions take place practically simultaneously.
The complete saturation of the purifying material by the foregoing impurities is
readily indicated by carbonic anhydride being detected at the outlet of the purifier
in quantity equal to that in which it is present at the inlet and when this is found to
be the case the purifier should be put out of action as the purifying power of the
alkali is then exhausted.
The exhausted material in the purifier consists mainly of carbonate of the alkali
employed free sulphur and sulphur derivatives of the alkali employed. The sulphur
may be recovered and the lime or other alkali be re causticised by the usual or any
suitable method.
By the process according to this Invention both sulphuretted hydrogen or other
sulphur compounds and carbonic anhydride may by one operation be completely or
almost completely removed from the impure gas.
The use of oxide of iron may be dispensed with when purifying the gas according
to this Invention and consequently the space and plant necessary for effecting the
purification of the Gas may be materially reduced a less quantity of lime is also
required than is required in purification as hitherto conducted and the exhausted
material from the purifier has no unpleasant odour or but little such odour and beyond
these advantages the process according to this Invention presents the great additional
advantage that the illuminating power of the gas is increased by the process of
purification instead of its being decreased as is the case when the purification is
carried on by the use of atmospheric air as, has hitherto been done. This is due
we believe to the fact that nitrogen is not present in any appreciable quantity when
we use oxygen according to our Invention the nitrogen présent in the air employed
in the processes mentioned having. the effect of decreasing the illuminating power of
the gas.
We wish it to be understood that we do not claim the use of atmospheric air.
Dated this 0th day of Mow 1000

page_text: COMPLETE SPECIFICATION.
Improvements in the Purification of Carburetted Hydrogen or
Coal Gas.
1 WILLIAM ANDREW MCINTOSH VALON of the Ramsgate Gas Works Civil
Engineer and BRIN'S OXYGEN COMPANY Limited of Connaught Mansions in the
City of Westminster do hereby declare the nature of this invention and in what
manner the same is to be performed to be particularly described and ascertained in
and by the following statement :-
This Invention has for its object to effect the purification of carburetted hydrogen
or coal gas in a better or more effectual manner than hitherto with much less space
and plant being necessary to effect the purification and with economy in time and
labour in manipulation.
According to this Invention oxygen gas preferably that which is produced according
to Brins process as described in the Specification of Letters Patent No. 157 of 1885
is passed into or mixed with the gas and the oxygen and the gas are then passed
together through purifiers containing caustic alkali preferably lime but the coal gas
and oxygen must not be passed into or mixed with the lime until after the tar and
ammonia and like impurities have been removed but when the gas contains as
impurities only carbonic anhydride and sulphur compounds. This introduction of
coal gas and oxygen to the lime after the tar and ammonia and like impurities have
been removed is important and essential to this Invention for the reasons hereinafter
stated. The proportion of oxygen gas employed will vary according to the amount
of impurities in the gas but generally for every one hundred grains of hydrogen
sulphide present in each one hundred cubic feet of the impure gas one part by
volume of the oxygen gas will be used for every one thousand parts by volume of
the gus to be purified. Care must be taken to remove the tar and ammonia and like
impurities before the oxygen is admitted as otherwise the resultant material in the
lime purifiers would be unmarketable and it would have the offensive odour of "blue
billy" together with the pungent odour of ammonia and it could only be removed
from the purifiers and otherwise manipulated after the greater part of the free and
loosely combined ammonia had been released. Moreover if the tar and ammonia and
like impurities be not first removed the sulphate of ammonia, at present one of the
most valuable bye-products produced in the distillation of coal and a considerable
part of the tar would be lost and the spent lime would form a dark coloured moist
and more or less granular mass impregnated with a considerable amount of tar and
of very small manurial value. When freshly taken from the lime purifiers the said ;
spent lime would contain only three to four per cent. of ammonia and a great part
of this would be so loosely combined that when the lime is exposed to the air for a
short time about two thirds of the ammonia would become dissipated, it in part being
set free by the caustic lime present in the spent lime and by the time the spent lime
was available as manure it would contain only one or one and a half per cent. of s
ammonia (the only constituent. of. manurial. value) so that it would be practically:.;

page_text: valueless. Further if such spent lime be kept in bulk intra-molecular change takes
place and the whole soon becomes a pasty mass of offensive odour evolving ammonia.
Moreover no ready test would be applicable to determine when the lime purifier was
exhausted and some such test is essential to the practical working of such a process.
Further the lime would become fouled in the purifiers much more quickly in the
presence of the tar, ammonia and like impurities and thus the often repeated self-
revivification which takes place in the process according to the present Invention would
be prevented. The spent lime, the product of the process according to the present
Invention, forms a dry and almost odourless mass, containing from ten to twelve per
cent. of sulphur most of which can be profitably recovered. Or at the least this
spent lime would be suitable for use as road ballast or the like and when it is kept in
bulk no apparent change occurs. In the process according to the present Invention
the carbonic acid test forms an easy means of ascertaining or indicating the state of
the lime in the purifier and the resultant spent lime being odourless can be readily
manipulated and removed. It is therefore essential to the success of the process of
purification of carburetted hydrogen or coal gas by means of oxygen and lime that
the tar and ammonia and like impurities be removed before the oxygen is introduced.
The tar and ammonia are thus saved as bye products and the re-actions taking place
in the lime purifier are quite different in the absence of ammonia from those which
occur in its presence.
The re-actions which take place owing to the use of oxygen gas in the process
according to the present invention are it is believed as follows:-
The calcium hydrate (presuming for the purpose of this example that lime is the
alkali used) takes up the sulphuretted hydrogen from the impure gas and forms a
sulphide of calcium which in its turn acts upon the sulphur compounds other than
sulphuretted hydrogen. The sulphide and other sulphur derivatives of calcium are
re-oxidized by the oxygen which has been passed into and mixed with the gas
according to this invention and are in great part revivified by being transformed into
calcium hydrate the sulphur being in great part separated as free sulphur. This
calcium hydrate is also capable of absorbing the carbonic anhydride with formation
of carbonate of lime as in the usual method of purification of lime. The aforesaid
re-actions take place practically simultaneously. The complete saturation of the
lime by the foregoing impurities is readily indicated by carbonic anhydride being
detected at the outlet of the purifier in quantity equal to or approaching that in
which it is present at the inlet and when this is found to be the case the purifier should
be put out of action, as the purifying power of the lime is then exhausted. The
exhausted lime in the purifier consists mainly of carbonate of lime, free sulphur
and sulphur derivatives of lime. The sulphur may be recovered and the lime be
revivified by the usual or any other suitable method.
By the process according to this invention both sulphuretted hydrogen or other
sulphur compounds and carbonic anhydride are by one operation completely or almost
completely removed from the impure gas.
The use of oxide of iron may be dispensed with when the gas is purified according
to this invention and consequently the space and plant necessary for effecting the
purification of the gas may be materially reduced and a less quantity of lime is
required than is required in purification as hitherto conducted and the exhausted
material from the purifier has no unpleasant odour and beyond these advantages the
process according to this invention presents the great additional advantage that the
illuminating power of the gas is increased by the process of purification instead of its
being decreased as is the case when the process is carried on by the use of atmospheric
air as has hitherto been done.
This is due it is believed to the fact that nitrogen is not present in any appreciable
quantity when we use oxygen according to our invention, the nitrogen present in the
air employed in the process mentioned having the effect of decreasing the illuminating
power of the gas. We wish it to be understood that we do not claim the use of
atmospheric air in purifying gas nor do we claim the supply of oxygen to the crude
gas coming from the retorts and before the tar, ammonia and like impurities have

page_text: been removed. Although we have mentioned lime especially for the more simple
description of the invention, we wish it to be understood that we do not limit our-
selves to the use of lime as other suitable alkali can be used as will be readily
understood by chemists.
The oxygen to be used may be stored in a gasometer and supplied by a pipe or
passage to the gas on its way from the washers or purifiers where the tar ammonia
and like impurities are removed to the lime or equivalent purifiers, the said pipe or
passage being provided with valves for controlling the passage of the oxygen. Or
the gas to be purified in the lime purifiers and the oxygen gas may be independently
admitted into the inlet end of the lime purifiers.
Having now particularly described and ascertained the nature of four said invention'
and in what manner the same is to be performed, we declare that what we
claim is :-
The purification of carburetted hydrogen or coal gas by means of oxygen passed
into or mixed with the carburetted hydrogen or coal gas, the said oxygen and
carburetted hydrogen or coal gas after the tar ammonia or like impurities have been
removed from the carburetted hydrogen or coal gas being passed into the purifiers
for removing the carbonic anhydride sulphuretted hydrogen and like impurities
substantially as hereinbefore explained.
L
1000