IMPROVEMENTS IN APPARATUS FOR BLEACHING PAPER PULP
Year: 1878

page_text: LETTERS PATENT to Sydney Pitt, of Sutton, in the County of Surrey, for the
Invention of "IMPROVEMENTS IN APPARATUS FOR BLEACHING PAPER PULP."
A communication from abroad by Auguste Pochez, junior, of St. Amand-les-
caux. France.
Sealed the 17th December 1878, and dated the 20th June 1878.
PROVISIONAL SPECIFICATION left by the said Sydney Pitt at the Office
of the Commissioners of Patents on the 20th June 1878.
SYDNEY PITT, of Sutton, in the County of Surrey.
IMPROVEMENTS IN APPA-
RATUS FOR BLEACHING PAPER PULP." [A communication from abroad by Auguste
Pochez, junior, of St. Amand-les-caux, France.]
This Invention has for its object improvements in apparatus for bleaching paper
pulp, more especially that obtained from straw, wood, esparto, or such like.
For this purpose I employ an oblong vat for containing the pulp to be bleached.
Immersed in this vat is the lower part of a stirring wheel, the axes of which have
upon them toothed wheels, which gear with toothed racks fixed upon the top of the
two opposite sides of the vat. The axis of the wheel is drawn to and fro, first
towards one end of the vat, and then towards the other, so that the wheel is caused
to revolve, and also to traverse from one end of the vat to the other. Moving to
and fro with the axis of the wheel is also a small truck or carriage, provided with
wheels, which run in grooves along the top of the two sides of the vat.
At each end of the truck is a trough passing transversely across the vat, and
these troughs are supplied with the bleaching liquid which has to be mixed with the
pulp.
At the bottom of the troughs are openings, provided with valves, by which the
passage of bleaching liquid from the troughs into the vat can be controlled. As
the truck and wheel are moved slowly to and fro from one end of the vat to the
other, the bleaching liquid is allowed to pass little by little, and continuously, into
the vat, and is at once intimately mixed with the pulp in the vat.

page_text: For moving to and fro the truck and axes of the stirring wheel, an endless chain
is used, passing over pullies at the ends of the tank. The axis of the pulley at one
end of the tank has a slow revolving notion given to it in one direction or the
other, by gearing from a driving shaft, on which are two loose pullies driven in
opposite directions, and either one or other of which can be made fast with the shaft
by a sliding clutch worked by a fork at one end of a clutch lever.
The opposite end of the clutch lever is coupled to the lower arm of an upright
lever, the upper arm of which carries a weight, and according as the weighted lever
arm is thrown over to one side or the other of the axis of the lever, so either one or
other of the loose driving wheels is made fast with the driving shaft.
In order automatically to move over the clutch lever from one position to the
other as the wheel and truck arrive at one or other end of the bath, the clutch lever
is connected by a link to an arm on a vertical axis near one end of the tank; on
this axis is a finger against which a projection on the truck acts when the truck has
arrived at this end of the tank and turns the axis, and so shifts over the clutch
lever, and reverses the movement of the truck and stirring wheel. At the opposite
end of the tank is a similar upright axis and finger, and an arm on this axis is
connected by a link to an arm on the upright axis first mentioned, so that at which-
ever end of the tank the truck arrives it strikes a finger, and so causes the move-
ment to be reversed.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Sydney Pitt in the Great Seal Patent Office on the 20th December
1.878.
SYDNEY PITT, of Sutton, in the County of Surrey. "IMPROVEMENTS IN APPA-
RATUS FOR BLEACHING PAPER PULP." A communication from abroad by Auguste
Pochez, junior, of St. Amand-les-eaux, France.
This Invention has for its object improvements in apparatus for bleaching paper
pulp, more especially that obtained froin straw, wood, asparto, or such like.
An apparatus constructed according to the Invention is shown in the Drawing
hereunto annexed.
Figure 1 is a longitudinal clevation, Figure
in section of the apparatus.
a plan, and Figure 3 an end view
The apparatus is composed of an oblong vat, lined with lead, for containing the
pulp to be bleached. Immersed in this vat is the lower part of a stirring wheel B,
the axes of which have upon them toothed wheels, which gear with toothed racks A
fixed upon the top of the two opposite sides of the vat. The wheel shown in the
Drawing is formed of a square cast-iron shaft encased in wood. To it are secured
arms c, c, Figure 1, tied together at intervals by cross pieces d, d. The axis of the
wheel is drawn to and fro, first towards one end of the vat, and then towards the
other, so that the wheel is caused to revolve, and also to traverse from one end of

page_text: the vat to the other. Moving to and fro with the axis of the wheel is also a small
truck or carriage G, provided with wheels f, which run on rails or trucks a between
the toothed racks and the interior of the vat.
At each end of the truck G is a trough H, lined with lead, and passing transversely
across the vat; these troughs are supplied with the bleaching liquid, which has to
be mixed with the pulp. They can be filled through the funnel F, which commu-
nicates with the two troughs by the pipes D.
At the bottom of the troughs H are openings b, b, provided with plugs or
valves g, g, by which the passage of bleaching liquid from the troughs into the vat
can be controlled. As the truck and wheel are moved slowly to and fro from one
end of the vat to the other, the bleaching liquid is allowed to pass little by little
and continuously into the vat, and is at once intimately mixed with the pulp in
the vat.
For moving to and fro the truck G and axes of the stirring wheel, an endless chain
is used, passing over pullies X, X, at the ends of the tank. The chain drives the
wheel Z, and so gives motion to the wheel. The axis of the pulley X at one end of
the tank has a slow revolving motion given to it in one direction or the other, by
gearing from a driving shaft K, on which are two loose pulleys I, I, driven in oppo-
site directions, and either one or other of which can be made fast with the shaft
by sliding clutches, worked by a fork J at one end of a clutch lever turning on a
contre at E.
The opposite ond T of the clutch lever is coupled to the lower arm of an upright
lever M, which turns on an axis m; the upper arm of this lever carries a weight N,
and according as the weighted lever arm is thrown over to one side or the other of
the axis m of the lever, so oither one or other of the loose driving wheels is made
fast with the driving shaft.
In order automatically to move over the clutch lever from one position to the
other, as the wheel and truck arrive at one or other end of the bath, the arm T of
the clutch lever is connected by a link to an arm p, which is on a vertical axis P,
near one end of the tank. On this axis P are two other arms n, n; one forms a
finger, against which a projection on the truck acts when the truck has arrived at
this end of the tank and turns the axis, and so shifts over the clutch lever and
reverses the movement of the truck and stirring wheel. At the opposite end of the
tank is a similar upright axis L and finger, and an arm on this axis is connected
by a link Q to the other arm n on the upright axis P first mentioned, so that at
whichever end of the tank the truck arrives it strikes a finger, and so causes the
movement to be reversed.
The wheel B should be revolved very slowly, say, about 6 or 7 turns a minute.
The action of the machine is as follows:-The pulp to be bleached, after having
been washed, is led into the vat and slightly acidified. During this operation the
chlorine solution is run from a tap Ⓡ into the two troughs H, and the stirring
wheel B is put into motion by inclining over to one or other side the counter-
weight N. Suppose, for example, it is inclined to the right, the left-hand pulley
will be clutched to and drive the shaft K, and the carriage will travel in the direc-
tion of the arrow. When one of the fingers s on the carriage G comes against the
arm or finger which projects from the axis L, it turns this axis, but as the axis is
coupled by the connected rod Q with the second axis P, it likewise turns this axis, .
and by the connecting rod q draws towards it the end of the arm T of the clutch
lever. The counterweight N is thus thrown over to the left, which will cause the
truck and wheel to be drawn in the opposite direction.
When the wheel has been put in motion, the valves g, g, are opened, which allows
the chlorine solution to pass slowly from the troughs H through a perforated pipe
or spreader on to the pulp in the vat.
The bleaching is effected in a few hours, and the pulp is neutralized; it is then
ready to be made into paper. It is drawn off from the vat by the valve V.
Among the advantages possessed by this machine may be mentioned,-
1. The cheapness and simplicity of its construction.

page_text: 2. The short time necessary for effecting the bleaching operation resulting from
the pulp, after having been slightly acidulated, having the chlorine solution applied
to it little by little and in a continuous manner until the troughs are empty, and
having the solution at once mixed up with it as it is introduced. From this an
economy arises, as the chlorine solution applied a little at a time is exhausted as
soon as it is introduced.
3. The pulp not being diluted with the chlorine solution, as is frequently the
case, it is easily turned over and over by the arms of the wheel, so allowing the
carbonic acid in the air to act upon the chlorine, which so soon as it is disengaged,
at once flies to the fibre. From this an economy results, which cannot be obtained
with the bleaching machines heretofore used.
4. As the machine is worked at a comparatively slow speed, the power required
to drive it is small.
Having thus described the nature of the Invention, and the manner of performing
the same, I would have it understood that I do not confine myself to the exact details
heroin-before given of the construction of the various parts of the machine, as these
inay be varied, but I claim the construction of apparatus for bleaching paper pulp,
substantially as herein-before described, and illustrated by the Drawings annexed.
In witness whereof, I; the said Sydney Pitt, have hereunto set my hand
and seal, this Seventeenth day of December, in the year of our Lord One
thousand eight hundred and seventy-eight.
".
SYDNEY DITU