IMPROVEMENTS IN THE MANUFACTURE OF ALKALI AND IN APPARATUS EMPLOYED THEREIN.
Year: 1871

page_text: LETTERS PATENT to Charles Wigg, of Liverpool, in the County of
Lancaster, Alkali Manufacturer, for the Invention of "IMPROVEMENTS
IN THE MANUFACTURE OF ALKALI AND IN APPARATUS EMPLOYED THEREIN.'
"
of the Commisioners of Patents, with his Petition and Declaration,
on the 17th March 1871, pursuant to the 9th Section of the Patent
Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CHARLES
WIGG, of Liverpool, in the County of Lancaster, Alkali Manufacturer,
send greeting.
WHEREAS I am in possession of an Invention for "IMPROVEMENTS IN
THE MANUFACTURE OF ALKALI AND IN APPARATUS EMPLOYED THEREIN," and have
petitioned Her most Excellent Majesty Queen Victoria to grant unto

page_text: me, my executors, administrators, and assigns, Her Royal Letters Patent
for the same, and have made solemn Declaration that I am the first and
true Inventor thereof.
NOW KNOW YE, that I, the said Charles Wigg, do hereby declare the
nature of the said Invention to be as follows:-
This Invention has for its object "Improvements in the Manufacture
of Alkali and in Apparatus employed therein."
In the manufacture of alkali from common salt the salt has to be
converted into sulphate of soda. It is for this purpose mixed with
sulphuric acid in a heated pan, and so a partial conversion is obtained,
which is completed by transferring the material to a furnace and there
applying a higher heat.
According to this Invention the apparatus is arranged and the
process is conducted in the manner following:-Crude coal gas pro-
duced in the ordinary way by the partial combustion of coal or slack in
a gas producer, constructed similarly to those now in common use, is
burnt under the bed of the furnace in flues suitably constructed, and
sufficient air is admitted and allowed to mix with the gas. The flame
and heated products of combustion after traversing the flues 'under the
bed of the furnace pass up through passages in the brickwork and are
led over the bed of the furnace, thus coming in contact with the charge
of salt cake to be roasted. The heated air mixed with the acid vapour
rising from the charge passes away to the condenser through a brick or
iron flue. The decomposing pan which is used in connection with the
furnace is also heated with gas. The hole connecting this pan with the
furnace and through which the charge is pushed is, after the pushing,
stopped by a sliding damper or by other means so as to separate the
acid vapour liberated in the decomposing pan from that of the furnace.
It is conveyed away in a separate flue or pipe to the condensers.
In order that my said Invention may be most fully understood and
readily carried into effect, I will proceed to describe the Drawings here-
unto annexed

page_text: Figure 3 is a transverse section taken at the line A, B, in Figures
1 and 2.
u, u, is the main gas fluc conveying gas from generators such as are
used in connection with a Siemens furnace. By the passages b, b, the
gas is led to the combustion flues c, c, running underneath the bed of
the furnace from end to end. As the gas enters these flues it is met
by streams of atmospheric air drawn in by the draft of the chimney at
the air holes d, d. The gas thus mixed with air is ignited, and in this
state traverses the flues c, c, and heats the bed of the furnace. The
flame and products of combustion then ascend into the body of the
furnace and return in contact with the material on the bed, thus passing
to the flue e leading to the ordinary condensing towers, and thence to
the high chimney of the works. The panf is similarly heated by the
combustion of gas; there is a circular chamber built beneath the pan,
to which gas is supplied by the channel g, air also enters by the opening
7. The flame and products of combustion pass out by openings in the
wall of the chamber immediately beneath the pan bottom into an outer
chamber which a flue connects with the high chimney.
In working the apparatus, as is usual, the partial conversion of one
batch of salt is effected in the pan, whilst the conversion of another
batch is completed in the furnace by the higher heat to which it is there
exposed. The sulphuric acid and salt are mixed in the pan, and the
acid fumes evolved are drawn off by the flue i and condensed, and the
strong acid thus resulting is collected and stored in a cistern until
required for use. When the charge has been drawn out of the furnace
the passage I between the pan and the furnace (which up to this point
has been closed) is opened, and the contents of the pan are transferred
to the bed of the furnace, the passage is then again closed and the pan
is recharged. The acid fumes drawn off in the furnace pass away with
the products of combustion to the condensing towers, where the fumes
are condensed by streams of water, and a weak impure acid is obtained.
Having thus described the nature of my said invention, and the
manner of performing the same, I would have it understood that what I
claim as my improvements in the manufacture of alkali and in appa-
ratus employed therein is, the construction and use of the apparatus
consisting of a converting furnace and pan, such furnace being licated
by means of gas ignited in flues under the furnace bed and then led over

page_text: the bed and in contact with the materials. thercon, substantially as
described.
In witness whereof, I, the said Charles Wigg, have hereunto set
my hand and seal,, this. Fifteenth day of March, in the year of
Our Lord One thousand eight hundred and seventy-one..
CHARLES WIGG. (L.S.).