Products and Tar from Producer or other Furnace Gases.
Year: 1885

page_text: Products and Tar from Producer or other Furnace Gases.
I, LUDWIG MOND of Winnington Hall in the County of Chester, Manufacturing
Chemist do hereby declare the nature of my said invention for "IMPROVEMENTS
IN OR INCIDENTAL TO THE SEPARATION OF AMMONIACAL PRODUCTS AND TAR FROM
PRODUCER OR OTHER FURNACE GASES to be as follows:-
In order to condense ammoniacal products and tar from producer or furnace
gases, these gases have hitherto been cooled by passing them through iron conduits
exposed to the air or surrounded by water. In either case this operation has been
found very tedious, and has required enormous surfaces on account of the slowness
with which the heat is taken up from the hot gases by the sides of a conduit
through which these gases pass; and in the case of producer gases obtained under
my patents Nos 3821 and 3923 of 1883, which contain a large percentage of steam,
these difficulties have again been much aggravated by the large amount of heat
stored up as latent heat in the steam, and which has all to be abstracted from the
gas by cooling.
To overcome this difficulty I have devised the following method.
I. I pass the gases through a scrubber or series of scrubbers of any convenient
construction, in which I bring them into direct and intimate contact with a quantity
of water sufficient to reduce the temperature of the gases to below 40 degrees
centigrade, and passing through the scrubbers in a direction opposite to the current
of gas. The water issuing from these scrubbers has absorbed the ammonia and
ammoniacal compounds, and has condensed the tarry matters, which remain sus-
pended in it, but contains both in very small quantities; it has also condensed the
steam contained in the gases and has become hot. This hot water I pass through
a methodical cooling apparatus through which it flows in one direction, while a
current of cold water flows in the opposite direction. By preference I use wrought
iron cylinders, in which a large number of wrought iron pipes have been fixed in
the manner used in surface condensers. In these coolers I have a hot liquid on one
side and a cold liquid on the other, and am therefore able to pass a very much
larger amount of heat through the iron tubes or plates separating the two liquids
than I could if I had gas on one side and a liquid on the other, therefore very much
smaller cooling surfaces will effect my object.
The water issuing from the scrubbers after being passed through these coolers is
again passed through the scrubbers, then again through the coolers, and so on; the
same water being constantly used. On its way from the scrubber to the cooler, and
from the cooler to the scrubber, the water is passed through a tank of sufficient size
to allow the tarry matters to separate from the water. The tar accumulating in
these tanks is removed from time to time.
The steam in the producer gases being condensed by this treatment, the volume
of water passing through the scrubbers gradually increases. A quantity of water

page_text: equivalent to the condensed steam is from time to time abstracted. This contains
a sufficient quantity of ammonia to make it readily available for the manufacture
of ammonia or its salts by distillation, or other well known methods.
When I want to obtain the Ammonia in the form of sulphate direct I pass the
gases issuing from the gas-producers into a scrubber or series of scrubbers, through
which I pass a very dilute solution of sulphuric acid, not exceeding 2 of oil of
vitriol to 100 of water. Other acids can of course also be used, such as hydro-
chloric or phosphoric acid, but I prefer sulphuric acid.
These scrubbers are maintained by the heat of the gases at a temperature of
about 100 degrees centigrade, so that no steam is condensed in these scrubbers.
The ammonia is absorbed in these scrubbers by the sulphuric acid, and the heavy
portions of the tarry matters are condensed and flow out of the scrubbers with the
solution of sulphate of ammonia formed therein.
I use the sulphuric acid so very weak, so that it shall not act on these tarry
matters. If it is used stronger, the tarry matters are dissolved by the sulphuric
acid and can no longer be separated from the solution of sulphate of ammonia.
To separate the tar, I run the solution through a sufficiently large vessel (separator)
in which the tar accumulates. The solution of sulphate of ammonia issuing from
this vessel is very weak, so that it would be very costly to utilise it by concentration
or distillation. I add sulphuric acid to this weak solution so as to bring it again
to the original acidity, and then pass it again through the scrubbers, and I continue
to do so, until I obtain a nearly concentrated solution of sulphate of ammonia,
from which the salt is then readily obtained in a marketable formn by crystallisation
and evaporation.
The gases after leaving these scrubbers are still at a temperature of 100 degrees
centigrade, and contain a large percentage of steam, which has been increased
beyond the original percentage by a certain amount of evaporation taking place in
the acid scrubbers. These gases may without inconvenience be burned without
previous condensation of the steam they contain But in this case, the latent heat
of this steam is entirely lost. In order to utilise this latent heat, I pass the gases
after they leave the acid scrubbers through a scrubber or series of scrubbers in
which they come into intimate contact with water passing in the opposite direction.
In these scrubbers steam is condensed together with the lighter portions of the tar,
and the water passing through them is raised to a temperature of from 90 degrees
to 100 degrees centigrade. This hot water, I pass through another scrubber or
series of scrubbers through which I draw in an opposite direction the air wanted
for burning the fuel in my gas producers. This air thus gets heated and fully
saturated with moisture at the temperature which it attains. If it reaches a tem-
perature of 80 degrees centigrade, it will in this way take up sufficient moisture to
make a further addition of steam unnecessary, when using this air in the gas-
producer, and even at a temperature considerably below 80 degrees, the air will
take up an amount of moisture which will very materially reduce the quantity of
steam hitherto used at the gas producers. Thus all or the greater part of the fuel
now used for raising steam for the purpose of working gas-producers under my
patents Nos 3821 and 3923 of 1883 will be saved, and the latent heat of the steam
once used, is thus utilised to produce this steam over and over again.
The tar which accumulates in the water used in these scrubbers is separated and
removed from time to time. If any ammonia escapes absorption in the acid
scrubber, it will be absorbed by the water in the subsequent scrubbers. As the
water heated in one of these scrubbers is cooled down in the subsequent scrubber,
the same water may be used over continually. It will then gradually absorb more
and more ammonia and may become sufficiently strong to make it worth while to
recover this ammonia by distillation or otherwise.

page_text: Products and Tar from Producer or other Furnace Gases.
I, LUDWIG MOND of Winnington Hall, in the county of Chester, Manufacturing
Chemist, 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:-
In order to condense ammoniacal products and tar from producer or furnace
gases, these gases have hitherto been cooled by passing them through iron conduits
exposed to the air, or surrounded by water. In either case this operation has been
found very tedious, and has required enormous surfaces on account of the slowness
with which the heat is taken up from the hot gases by the sides of a conduit
through which these gases pass; and in the case of producer gases obtained under
my Patents Nos 3821 and 3923 of 1883, which contain a large percentage of steam,
these difficulties have again been much aggravated by the large amount of heat
stored up as latent heat in the steam, and which has all to be abstracted from the
gas by cooling.
To overcome this difficulty I have devised the following method:-
I pass the gases through a scrubber or series of scrubbers of any convenient
construction, in which I bring them into direct and intimate contact with a
quantity of water sufficient to reduce the temperature of the gases to below
40 degrees centigrade, and passing through the scrubbers in a direction opposite
to the current of gas. The water issuing from these scrubbers has absorbed the
ammonia and ammoniacal compounds, and has condensed the tarry matters, which
remain suspended in it, but contains both in very small quantities; it has also
condensed the steam contained in the gases and has become hot.
This hot water
I pass through a methodical cooling apparatus, through which it flows in one
direction, while a current of cold water flows in the opposite direction. By
preference I use wrought iron cylinders, in which a large number of wrought iron
pipes have been fixed in the manner used in surface condensers.
In these coolers
I have a hot liquid on one side, and a cold liquid on the other, and am therefore
able to pass a very much larger amount of heat through the iron tubes or plates
separating the two liquids than I could if I had gas on one side and a liquid on the
other, therefore very much smaller cooling surfaces will effect my object.
The ammoniacal water issuing from the scrubbers after being passed through
these coolers is again passed through the scrubbers, then again through the coolers,
and so on; the same water being constantly used. On its way from the scrubber
to the cooler, and from the cooler to the scrubber the water is passed through a
tank of sufficient size to allow the tarry matters to separate from the water.
tar accumulating in these tanks is removed from time to time.
The
The steam in the producer gases being condensed by this treatment, the volume
of water passing through the scrubbers gradually increases. A quantity of water
equivalent to the condensed steam is from time to time abstracted. This contains

page_text: a sufficient quantity of ammonia to make it readily available for the manufacture
of ammonia or its salts by distillation or other well known methods.
The water used for cooling in the surface cooler takes up from the ammoniacal
water, the heat originally contained in the gases including the latent heat of the
steam contained therein and thereby becomes hot. This hot water I utilize as
hereinafter described.
When I want to obtain the ammonia in the form of sulphate direct I pass the
gases issuing from the gas producers into a scrubber or series of scrubbers, through
which I pass a very dilute solution of sulphuric acid, not exceeding 2 of oil of
vitriol to 100 of water. Other acids can of course also be used, such as hydrochloric
or phosphoric acid, but I prefer sulphuric acid.
These scrubbers are maintained by the heat of the gases at a temperature of
about 100 degrees centigrade so that no steam is condensed in these scrubbers.
The ammonia is absorbed in these scrubbers by the sulphuric acid, and the heavy
portions of the tarry matters are condensed and flow out of the scrubbers with
the solution of sulphate of ammonia formed therein.
I use the sulphuric acid so very weak, so that it shall not act on these tarry
matters. If it is used stronger the tarry matters are dissolved by the sulphuric
acid and can no longer be separated from the solution of sulphate of ammonia. To
separate the tar, I run the solution through a sufficiently large vessel (separator)
in which the tar accumulates. The solution of sulphate of ammonia issuing from
this vessel is very weak, so that it would be very costly to utilize it by concen-
tration or distillation. I add sulphuric acid to this weak solution so as to bring it
again to the original acidity and then pass it again through the scrubbers, and
I continue to do so, until I obtain a nearly concentrated solution of sulphate of
ammonia from which the salt is then readily obtained in a marketable form, by
crystallisation and evaporation.
The gases after leaving these scrubbers are still at a temperature of 100 degrees
centigrade and contain a large percentage of steam, which has been increased
beyond the original percentage by a certain amount of evaporation taking place in
the acid scrubbers. These gases may without inconvenience be burned without
previous condensation of the steam they contain. But in this case, the latent heat
of this steam is entirely lost. In order to utilise this latent heat, I pass the gases
after they leave the acid scrubbers through a scrubber or series of scrubbers in
which they come into intimate contact with water passing in the opposite direction.
In these scrubbers steam is condensed together with the lighter portions of the tar,
and the water passing through them is raised to a temperature of from 90 degrees
to 100 degrees centigrade. This hot water (or the water which has been used for
cooling in the surface coolers mentioned in the early part of this Specification and
has thereby become hot) I pass through another scrubber or series of scrubbers
through which I draw in an opposite direction the air wanted for burning the fuel
in my gas producers. This air thus gets heated and fully saturated with moisture
at the temperature which it attains. If it reaches a temperature of 80 degrees
centigrade, it will in this way take up sufficient moisture to make a further addition
of steam unnecessary when using this air in the gas producer, and even at a
temperature considerably below 80 degrees the air will take up an amount of
moisture which will very materially reduce the quantity of steam hitherto used at
the gas producers. Thus all, or the greater part of the fuel now used for raising
steam for the purpose of working gas-producers under my patents N°* 3821 and
3923 of 1883 will be saved, and the latent heat of the steam once used, is thus
utilized to produce this steam over and over again.
The tar which accumulates in the water used in these scrubbers is separated and
removed from time to time. If any ammonia escapes absorption in the acid
scrubber it will be absorbed by the water in the subsequent scrubbers. As the
water heated in one of these scrubbers is cooled down in the subsequent scrubber,
the same water may be used over continually. It will then gradually absorb more
and more ammonia, and may become sufficiently strong to make it worth while to

page_text: recover this ammonia by distillation or otherwise. Throughout this Specification
by the word "scrubber I wish to be understood to mean any suitable apparatus
used for bringing gases into intimate contact with liquids, such as absorbing towers,
mechanical washers, spray apparatus, and the like.
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 improved processes for separating ammoniacal products and tar from furnace
or producer gases and the extraction or utilization of the heat stored up in these
gases, substantially as described.