IMPROVEMENTS IN APPARATUS FOR THE MANUFACTURE OF ALKALI
Year: 1878

page_text: LETTERS PATENT to James Cochran Stevenson, M.P., Alkali Manufacturer, of
South Shields, in the County of Durham, for the Invention of "IMPROVEMENTS
IN APPARATUS FOR THE MANUFACTURE OF ALKALI."
Sealed the 28th March 1879, and dated the 18th October 1878.
PROVISIONAL SPECIFICATION left by the said James Cochran Stevenson
at the Office of the Commissioners of Patents on the 18th October 1878.
JAMES COCHRAN STEVENSON, M.P., Alkali Manufacturer, of South Shields, in the
County of Durham. "IMPROVEMENTS IN APPARATUS FOR THE MANUFACTURE OF
ALKALI."
This Invention applies to the pans in which alkaline solutions are evaporated
by surface heat, and consists in collecting the salts produced by the evaporation in
vessels or pockets placed below the level of the pan and communicating with it by
an aperture which may be closed with a valve or plug, the pockets being provided
with water-tight doors for the removal of the salts."
When the plug hole is opened the liquor in the pan fills the pocket, and as the
evaporation goes on the salts are raked by hand labour or moved by suitable
machinery to the plug hole and fall into the pocket, and so gradually fill it from
the bottom, displacing the liquor.
When one pocket is full or nearly full of salts its plug is put down, and another
pocket is opened to receive in its turn the salts from the pan.

page_text: The liquor in the pocket is drawn off by a tap in the bottom, and the salts when
sufficiently drained are removed by the water-tight door. The draining tap is then
shut and the door closed, and the plug being lifted the pocket fills with liquor from
the pan and is ready again to receive the salts.
A pipe is placed on the top of the pocket and terminates above the level of the
liquor in the pan, to allow of the escape of air when the pocket is being filled with
liquor.
In ordinary working the pan is kept full of liquor, and to prevent the accumu-
lation of salts in the pan one or more of the pockets must be open to receive them,
the remaining pockets being either empty or containing salts.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said James Cochran Stevenson in the Great Seal Patent Office on the
17th April 1879.
JAMES COCHRAN STEVENSON, M.P., Alkali Manufacturer, of South Shields, in the
County of Durham. "IMPROVEMENTS IN APPARATUS FOR THE MANUFACTURE OF
ALKALI."
'
This Invention applies to the pans in which alkaline solutions are evaporated
under an arch by heat or flame passing over the surface of the pan, and consists in
collecting the salts produced by the evaporation in vessels or pockets placed below
the level of the pan, and communicating with it by apertures which may be closed
with plugs or valves, the pockets being provided with taps for draining the liquor
from the salts and with water-tight doors by which the salts when drained may be
removed.
When the aperture is open the liquor in the pan fills the pocket, and as the
evaporation goes on the salts are raked by a workman or moved by suitable
machinery to the aperture and fall into the pocket, and so gradually fill it from the
bottom, displacing the liquor.
When the pocket is full or nearly full of salts its plug is put down, and another
pocket is opened to receive in its turn the salts produced by the continued
evaporation.
The liquor remaining in the full pocket is drained off by the tap in the bottom,
and the salts when sufficiently drained are removed by the door.
A false bottom may be placed in the pocket to facilitate the draining of the
salts.
After the removal of the salts the tap and the door are closed, and the plug being
lifted the liquor from the pan fills the pocket, the air in the pocket escaping by
a pipe placed on the top of the pocket and terminating above the level of the liquor
in the pan.
In ordinary working the pan is kept full or nearly full of liquor, and to prevent
the accumulation of salts in the pan one or more of the pockets must be open to
receive them, the remaining pockets being either empty, waiting their turn to be
filled, or containing salts, which having been sufficiently drained are waiting to be
removed.
The accompanying Drawings show a plan and section of the surface heat
evaporating pan, in which the same letters refer respectively to the same parts of
the apparatus.
The pockets P communicate with the pan by the openings Q, which may be
closed by the plugs R. The tap T and the door U being closed and the plug R
being lifted as the evaporation of the liquor in the pan proceeds, and as the salts
are deposited on the bottom of the pan they are moved by the workman by means
of a rake which he works through the side opening S in the springing of the arch
over the pan, so that they fall through the opening Q and gradually fill the pocket,
displacing the liquor.
When one pocket is full or nearly full of salts its plug is put down and the
liquor is drawn off by opening the tap T, and the salts when sufficiently drained,
which is assisted by the false bottom V, are removed by the door U.
The tap Tand the door U are then closed, and the plug R being lifted the pocket
is filled with liquor from the pan, the pipe X allowing the air to escape.
The most convenient shape for the pockets is a cylinder surmounted by a
truncated cone of which the summit is the plug hole, the object being that the
pocket when filled shall hold the largest amount of salts with the smallest amount
of liquor. But the shape may be modified to suit the convenience of construction
and the requirements of the situation.

page_text: Machinery may be employed to move the salts to the plug holes by means of
rakes scraping the bottom, or a circular current may be produced in the liquor by
arms attached to a vertical shaft by which the salts may be moved so as to fall into
the open apertures of the pockets.
In this Invention I claim the combination of a surface evaporating pan with a
pocket underneath to receive the salts, and with an aperture between the pan and
the pocket with a plug or appliance for the opening or closing of the same, so that
communication between the pan and the pocket may be opened to allow the salts
to pass into the pocket and closed to allow the salts to be drained in the pocket,
substantially as described.
In witness whereof, I, the said James Cochran Stevenson, have hereunto set
my hand and seal, this Third day of April, in the year of our Lord One
thousand eight hundred and seventy-nine.