IMPROVEMENTS IN THE PURIFICATION OF COAL GAS
Year: 1881

page_text: LETTERS PATENT to John Berger Spence and Joseph Desvignes, both of
Lombard Street, in the City of London, for an Invention of "IMPROVEMENTS
IN THE PURIFICATION OF COAL GAS."
PROVISIONAL SPECIFICATION left by the said John Berger Spence and
Joseph Desvignes at the Office of the Commissioners of Patents on the
2nd December 1881.
JOHN BERGER SPENCE and JOSEPH DESVIGNES both of Lombard Street in the
City of London "IMPROVEMENTS IN THE PURIFICATION OF COAL GAS "
The object of our Invention is to remove from coal gas the ammonia with which
it is charged in such a manner that the use of scrubbers may be dispensed with.
To this end we take natural phosphate of alumina such as that known as
redonda phosphate and dissolve it in sulphuric acid by which means we obtain a
sulphate of alumina and free phosphoric acid. We then treat the mass with
carbonate of lime in sufficient quantity to neutralize any free sulphuric acid that
may be in the mass.
Or we may use ammonia water to effect the same object. The mass is then
dried artificially so as to obtain it in the form of a powder which will be permeable
to gas and the powder is placed in a puritier of the ordinary construction and the
gas is passed through it. .
In passing through the purifier the gas looses its ammonia which combines with
the sulphuric acid combined with the alumina and forms sulphate of ammonia.
The gas is next passed to a second purifier containing oxide of iron or other
suitable purifying agent where it parts with the sulphur and carbonic acid in the
ordinary way.
The alumina compound when thoroughly saturated with ammonia is removed
from the purifier and may be used alone or with other materials as manure or
for any other purpose to which it is applicable or it may be treated in any suitablo
manner to recover the ammonia.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said John Berger Spenco and Joseph Desvignes in the Great Scal
Patent Office on the 2nd June 1882.
JOHN BERGER SPENCE and JOSEPH DESVIGNES both of Lombard Street in the
City of London "IMPROVEMENTS IN THE PURIFICATION OF COAL GAS".
The object of our Invention is to remove from coal gas, the ammonia with which
it is charged on leaving the retort, in such a manner that the use of scrubbers will
be rendered unnecessary
In carrying out our Invention we employ natural phosphate of alumina such as
that known as redonda phosphate- The phosphate we mix with sulphuric acid
and subject the same to heat in a suitable vessel for from three to four hours,
stirring the mass from time to time to effect an intimate mixture
The mass which consists of sulphate of alumina impregnated with phosphoric
acid is allowed to cool and is then treated with carbonate of lime or of magnesia
..in sufficient quantity to neutralize any free sulphuric or phosphoric acid that
may be in the mass
Instead of the carbonate of lime or of magnesia to neutralize the free acid we
may sprinkle the mass with ammonia water which will have the same effect.
The mass is then dried and crushed into a powder permeable to gas and is
placed in a purifier of the ordinary construction used in gas works, and the gas is
passed through it.
In passing through this purifier the gas loses its ammonia which is taken up by
the sulphuric acid combined with the alumina and is formed into sulphate of
ammonia
The gas is then passed through a second purifier containing oxide of iron or
other suitable purifying agent to get rid of the sulphur and carbonic acid in the
ordinary way.
The alumina compound when thoroughly saturated with ammonia is removed
from the purifier and may be used either alone or with other materials as manure,
or for any other purpose to which it is applicable, as for instance for the
manufacture of alum, or it may be treated in any well known manner to recover
the ammonia
The sulphuric acid which we prefer to use is of the specific gravity of about one
hundred degrees Twaddle and is employed in the proportion of say ten hundred-
weight of sulphuric acid to one ton of phosphate
Having now described the nature of our Invention for improvements in the
purification of coal gas and explained the manner of carrying tlie same into effect,
we claim :
Removing the ammonia from coal gas by passing the gas through a purifying
agent composed of phosphate of alumina and sulphuric acid, substantially as herein
described
In witness whereof I the said John Berger Spence have hereunto set iny
hand and seal this Second day of June in the year of our Lord One
thousand eight hundred and eighty two.