IMPROVED MEANS OF OBTAINING AMMONIA FROM FURNACE GASES
Year: 1882

page_text: LETTERS PATENT to John Addie and James Addie both of Glasgow in the
County of Lanark North Britain Iron Masters for an Invention. of
"IMPROVED MEANS OF OBTAINING AMMONIA FROM FURNACE GASES "
PROVISIONAL SPECIFICATION left by the said John Addie and James
Addie at the Office of the Commissioners of Patents on the 6th October
1882.
JOHN ADDIE and JAMES ADDIE, both of Glasgow, in the county of Lanark,
North Britain, Ironmasters, "IMPROVED MEANS OF OBTAINING AMMONIA FROM
FURNACE GASES"
This Invention has for its object the fixing of the ammonia in the gases from
blast furnaces as well as other furnaces and gas-producers by means of an acid in
the form of a gas or vapour, and subsequently condensing and recovering the
compound thus formed.
The acid we prefer to use is sulphurous acid, but hydrochloric acid or sulphuric
acid in the form of vapour may also be used.
We produce the sulphurous acid by the combustion of sulphur or any substance
containing sulphur, such as pyrites, ironstone rich in sulphur, or the spent oxide of
iron from gas works, and force or draw the sulphurous acid thus produced into the
gases from the furnace, whereby a sulphite of ammonia (which may be more or less
mixed with sulphate of ammonia) is formed; and this compound we condense in
water, or obtain solid by any cooling process.
The ammonia thus condensed may be subsequently converted into sulphate of
ammonia, or it may be obtained in the free state by any of the usual methods.
The hydrochloric acid and sulphuric acid in the form of vapour inay be obtained
in any of the usual ways.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said John Addio and James Addie in the Great Seal Patent Office on
the 6th April 1883.
JOHN ADDIE and JAMES ADDIE both of Glasgow in the County of Lanark,
North Britain, Ironmasters "IMPROVED MEANS OF OBTAINING AMMONIA FROM
FURNACE GASES
"7
Our said Invention has for its object the fixing of the ammonia in the gases from
blast furnaces, as well as other furnaces and gas producers.by means of an acid in
the form of a gas or vapour, and subsequently condensing and recovering the
compound thus formed.
The acid wo prefer to use is sulphurous acid but hydrochloric acid or sulphuric
acid in the form of gas or vapour, may also be used. We produce the sulphurous
'acid by the combustion of sulphur, or any substance containing sulphur, such as
pyrites, ironstone rich in sulphur, or the spent oxide of iron from gis-works, and
force or draw the sulphurous acid thus produced into the gases from the furnace,
whereby a sulphite of ammonia (which may be more or less mixed with sulphate
and hyposulphite of ammonia) is formed; and this compound we condense or
dissolve in water.
The ammonia thus condensed or dissolved may be subsequently converted into
sulphate of ammonia, or it may be obtained in the free state by any of the usual
.methods.
The hydrochloric acid and sulphuric acid, in the form of gas or vapor may be
obtained by any known method.
"
By the term furnace gases" employed herein we mean the gases or gaseous
products resulting from the combustion, distillation, or coking of coal or other
carbonaceous matter, and our Invention is applicable to the treatment of such
gases whether from blast furnaces, gas producers, coking ovens, retorts, or other
furnaces.
The accompanying drawings in which Figure 1 is an elevation, and Figure 2 a
plan, illustrate one modification of apparatus used in carrying out our Invention.
This apparatus comprises two large scrubbers A and B to which the hot furnace
gases are led (either direct from the furnaces, or after their heat has been partially
utilised) by a large pipe C entering the first scrubber A at the lower end. In close
proximity to the scrubbers are two retorts or chambers D, wherein sulphurous acid
-gas is generated by the combustion of sulphurous sliale or of any other suitable
material. A blast of air to force combustion is led by pipes D' into the retorts D.
The sulphurous acid gas therein generated is led off by a pipe or pipes E leading
to and discharging into the pipe C by which the furnace gases are led to the
scrubbers. By so. connecting these pipes the sulphurous acid gas combines with
the ammonia and the furnace gases and forms a sulphite of ammonia.
The gases containing the sulphite of ammonia pass up through the first
scrubbor A and are washod by a descending stream: of water, which percolates
through a spray plate A', and a series of perforated plates A, a large proportion of
the sulphite being, absorbed or dissolved by the water in this scrubber. From the
scrubber A the gases pass by a neck or pipe a connecting the two scrubbers, and
descend through the second scrubber B in which they are washed by a second

page_text: stream of water passing through the spray plate B¹ and perforated plates B². In
this scrubber the water absorbs or dissolves any sulphite of ammonia remaining in
the gases. From the second scrubber the residual gases escape or are drawn off by
a pipe F, and may be utilized for heating or for other purposes, or be discharged
into the atmosphère.
.
The water used to absorb and dissolve the sulphite of ammonia in the furnace
gases passing through the scrubbers A and B, collects in tanks or vessels A³, B³, at
the lower end of each scrubber, and thence the liquor is withdrawn through
pipes g, g by means of a pump G, which forces the liquor up to the top of the
scrubbers A, B, through pipes g¹ gl and causes a' continuous circulation through
the scrubbers until the liquor in each is sufficiently saturated with the sulphite.
The liquor is then run off through suitable pipes l, separated from the tar or other
products in it, and then treated to convert the sulphite into sulphate of ammonia,
or otherwise utilised. Hinged and weighted doors I are fitted over openings in the
sides of the scrubber to allow of escape of the gases when there is too great
pressure inside.
In case of the spray plate becoming choked by the liquor in the upper end of the
scrubber, pipes J are provided to lead the liquor from the upper to the underside
of the spray plates A¹ B'.
The liquor in the first scrubber becomes more rapidly saturated than that in the
second scrubber, and when it is run off, the liquor in the second scrubber may be
run into the first and fresh water circulated through the second.
The furnace gases may be passed through the scrubber A and washed with
water to separate out the tar before the sulphite of ammonia is formed. In this
case the sulphurous acid gas may be admitted by a pipe entering the neck a to
combine with the furnace gases and form the sulphite before or while the gases pass
through the second scrubber B. The sulphite will be collected from the tank of the
second scrubber, and the tar and other products from the first scrubber.
In applying our process for recovering ammonia from furnace gases which are
afterwards to be used for any process in which the presence of acid is objectionable
(as for example the furnace gases to be used in the manufacture of steel) we
remove this acid by causing the furnace gases to pass through a scrubber containing
milk of lime or other alkali.
Substantially the same arrangement of apparatus may be used to condense and
recover the salt or compound formed when the ammonia in the furnace gases is
fixed by means of sulphuric acid gas or vapour or by hydrochloric acid gas or
vapor.
The sulphuric acid in the form of gas or vapour may be obtained by the forced
combustion of sulphate of iron, and the hydrochloric acid in the form of gas or
vapour may be obtained by heating a mixture of common salt and sulphuric acid;
or other known methods may be adopted for obtaining these acids in the form of
gas or vapor. The compound formed when sulphuric acid gas or vapour is used
to fix the aminonia in the furnace gases will be sulphate of ammonia, and the
compound formed when hydrochloric acid gas or vapour is employed will be
chloride of ammonium or muriate of ammonia.
Any other suitable arrangement of apparatus may be used to condense and
recover the salts or compounds of ammonia formed by the process herein described.
Having now particularly described and ascertained the nature of our said
Invention and in what manner the same is to be performed, we have to state that
we do not claim as new the arrangements of apparatus herein described and
illustrated, nor on the other hand do we confine ourselves to any particular
arrangement of apparatus for carrying out our Invention, but what we do
claim is.
The process herein described of obtaining ammonia from furnace gases which
consists in fixing the ammonia in such gases by mixing therewith sulphurous acid,

page_text: or sulphuric acid, or hydrochloric acid, in the form of gas or vapour and
subsequently condensing or dissolving and recovering the salts or compounds
thereby formed substantially in the manner herein set forth.
*51
In witness whereof I the said John Addie on behalf of myself.and the
said James Addie have hereunto set my hand and seal this thirteenth day of
March in the year of our Lord One thousand eight hundred and eighty
three.
Witness
WALLACE FAIRWEATHER O.E., Fel. Inst. P.A.
96 Buchanan Street
Glasgow.
JOHN ADDIE (L.S.)