IM- PROVEMENTS IN STEAM POWER FURNACES FOR THE MANUFACTURE OF SULPHATE OF SODA AND POTASH AND THE CALCINATION OF ALKALIES AND OTHER MATERIALS."
Year: 1876

page_text: LETTERS PATENT to George Dryden Mease, of the Lake Chemical Works,
"
South Shields, in the County of Northumberland, for the Invention of IM-
PROVEMENTS IN STEAM POWER FURNACES FOR THE MANUFACTURE OF SULPHATE
OF SODA AND POTASH AND THE CALCINATION OF ALKALIES AND OTHER
MATERIALS."
Sealed the 23rd February 1877, and dated the 22nd September 1876.
PROVISIONAL SPECIFICATION left by the said George Dryden Mease at the
Office of the Commissioners of Patents on the 22nd September 1876.
GEORGE DRYDEN MEASE, of the Lake Chemical Works, South Shields, in the
County of Northumberland. IMPROVEMENTS IN STEAM POWER FURNACES FOR
THE MANUFACTURE OF SULPHATE OF SODA AND POTASH AND THE CALCINATION OF
ALKALIES AND OTHER MATERIALS."
When manufacturing chemicals in circular horizontal steam power furnaces, two
kinds of furnaces are available. In the first the furnace bottom is stationary and
the stirrers revolve round the axis; in the second the stirrers are stationary and the
furnace bottom revolves round the axis.
When using a furnace of either kind for manufacturing sulphates of soda or
potash from the chlorides of the same salt and sulphuric acid there is a great waste
of heat, owing to the fact that the evolution of half the hydrochloric acid and the
evaporation of the water only requires a low temperature, whereas the remainder of
the hydrochloric acid requires a red heat to remove it. The introduction of cold
salt and comparatively cold sulphuric acid into the pan from which the hot
sulphate has been removed is also liable to crack the pan, and the sudden unequal
contraction is apt to make it leak at the segmental joints.
I use a double furnace consisting of two flat metal pans about 16 feet diameter,
and put them at different levels. The lower pan is next the fire, and the products
of combustion pass over this lower and nearer pan and thence over the further and
[Prine A1

page_text: higher one. The higher furnace bottom is stationary and the stirrers revolve round
the axis. The lower furnace bottom revolves round the axis and the stirrers are
stationary.
I put the salt and sulphuric acid into the higher furnace, and by means of ploughs
attached to the revolving arms turn it over until the evolution of gas and water
has nearly ceased. I then reverse the motion of the arms, and the backs of the
ploughs being made at an angle of 45° to the radial lines of the furnace the semi-
liquid sulphate is driven towards and against the sides of the pan. The pan has a
perpendicular ledge all round, about 18 inches high, except on the side next to the
lower pan where there is a space of about two feet where the sulphate passes out.
Fastened to the pan at this point is a flat semicircular guard 4 or 5 feet in
diameter, the semicircumference of which is set towards the opening in the side of
the large pan.
The bottom of this guard slopes upward, the top edge being about
12 inches above the level of the bottom of the large pan. This guard has a rim
round the semicircumference except where it joins the opening of the large pan.
By this arrangement the sulphate cannot escape until it is 12 inches above the level
of the large pan.
To discharge the sulphate I cause to revolve parallel to the
sloping surface of the guard curved blades, which sweep the whole surface of
the guard and throw the semi-liquid sulphate over the edge into the lower pan.
The lower pan or furnace bottom revolves, and the stirrers are stationary as
mentioned before.
I stir the sulphate in the lower pan as follows:-I make two doors on opposite
sides of the furnace, one of which is the discharging door. Through these doors or-
in a recess at one side of them I place a girder formed of two tubes or hollow box-
shaped castings, these pass right through the furnace and project a little on either
side, and the outside air can thus circulate through them without entering the
furnace. If necessary air or steam can be blown through to keep them cool, I put
between these hollow castings the necks of the ploughs or stirrers to protect them
from the heat. By making the backs of these ploughs at an angle of 45° to the
concentric circles of the pan, and reversing the furnace the sulphate can be driven
to and out of the discharging door.
The discharge is facilitated by the workman putting in a tool shaped like a large
shovel and held at the angle mentioned above. Or the following plan may be
adopted. I put a girder consisting of two hollow castings through the furnace on
the other side of the doors to the plough girder, and between these castings are the
necks of discharging plates; these plates extend half way across the furnace on the
side next to the discharging door. They are arranged at an angle of 45° to
concentric circles, the same as those in a Patent granted to Thomas Gibb and
Charles Gelstharp, No. 3074, A.D. 1869, but in this case they are not parallel, as the
lines of the girder are not radial. I suspend the girder by chains outside of the
furnace at such a height that the bottoms of plates are level with the surface of the
sulphate; when the sulphate is discharged from the upper furnace these plates level
it at once. When I wish to discharge the sulphate from the revolving furnace
I lower these plates which sweep it out of the furnace into a series of waggons.
Another advantage gained by placing the girders through the doors of the
furnace is that in case of repairs being required either girder with its attachments
can be moved out of the furnace and another put in its place in a few minutes. I
draw forward a series of waggons to receive in succession the discharged sulphate as
follows: The chains which suspend the discharging girder and by which it is
gradually lowered as the operation of discharging progresses are attached to a drum
and this drum is connected by toothed wheels and a screw to another drum to
which the chain is attached, which pulls the wagons past the door of the furnace.
The motion of the discharging girder from the surface of the sulphate to the bottom
of the pan is made to correspond to the passage of the whole series of waggons past
the door of the furnace. Thus, if the girder has to fall 9 inches and the train of
waggons is 30 feet long the waggon drum is made to gather up its chain forty times

page_text: faster than the girder drum releases its chain. The weight of the girder helps to
pull the waggons.
When calcining soda ash alkalies or other substances it is only advisable to use
a single furnace corresponding to the lower furnace of the arrangement above
described, and which revolves but has stationary girders, and the same stirring and
discharging arrangements that are mentioned above.