IMPROVE- MENTS IN APPARATUS FOR STRAINING PULP
Year: 1879

page_text: LETTERS PATENT to John Wood and Robert Wood, of Leith, in the County
of Mid Lothian, North Britain, Engineers, for the Invention of "IMPROVE-
MENTS IN APPARATUS FOR STRAINING PULP."
Sealed the 10th February 1880, and dated the 27th August 1879.
PROVISIONAL SPECIFICATION left by the said John Wood and Robert Wood
at the Office of the Commissioners of Patents on the 27th August 1379.
JOHN WOOD and ROBERT WOOD, of Leith, in the County of Mid Lothian, North
Britain, Engineers. "IMPROVEMENTS IN APPARATUS FOR STRAINING PULP."
This Invention comprises improvements in rotating pulp-straining apparatus of
the kind described in the Specification of Letters Patent granted to the present
applicants, and dated 24 October 1872 (No. 3146), and also a modifictaion in
which the apparatus does not rotate.
The present Invention consists principally in combining with the pump, applied
as described in the Specification referred to, a bag, envelope, or cover of a suitable
flexible but impermeable material, by means of which material the action of the
pump is communicated to the pulp inside of or under the strainer plates. Vulcanised
rubber combined with a woven fabric is convenient and suitable as the flexible
material, but other impermeable flexible materials may be employed. In applying
the improvements in connection with a rotating strainer casing the casing is formed
with hollow trunnions as formerly, that at one end serving for the exit of the
strained pulp whilst that at the other end is connected to the pump, which pump
is, by preference, of the kind having a plunger working through a stuffing box.
The trunnion connected with the pump communicates inside the strainer casing
with the interior of a frame, which may be constructed of wood or other suitable
material, and which is covered with the impermeable flexible material, and is shaped
to present a cylindrical, square, or other prismatic form, the end furthest from the
trunnion being also closed by the impermeable flexible material or otherwise.
Inside of the bag frame there is, by preference, fixed a block, or closed shell, or box
of wood, or other suitable material, for the purpose of occupying the central part

page_text: and diminishing the quantity of fluid acted on by the pump; the end of this block
nearest the pump being tapered and rounded. The fluid in the bag and pump may
be air or any other suitable fluid, gaseous or liquid, and when air is used an inlet
valve is provided in connection with the pump to admit air to make up for any
slight leakage.
In the modification, in which the apparatus does not rotate, the strainer plates
are fixed horizontally across the pulp vat, and at a little distance beneath them
there is fixed an open frame covered on..its upper side with the impermeable
flexible material. The pump communicates with the space under the flexible cover,
which space is otherwise closed, and the.discharge duct for the pulp communicates
with the space between the flexible cover and the strainer, plates.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John Wood and Robert Wood in the Great Seal Patent Office on the
25th February 1880.
JOHN WOOD and ROBERT WOOD, of Leith, in the County of Mid Lothian, North
Britain, Engineers. IMPROVEMENTS IN APPARATUS FOR STRAINING PULP."
"
Our said Invention comprises improvements in rotating pulp-straining apparatus.
of the kind described in the Specification of Letters Patent granted to us, and dated.
24 October 1872 (No. 3146), and also a modification in which the apparatus does.
not rotate.
:
Our present Invention consists principally in combining with the pump, applied
as described in our earlier Specification herein before referred to, a bag, envelope, or
cover of a suitable flexible but impermeable material, by means of which material
the action of the pump is communicated to the pulp inside of or under the strainer.
plates. The fluid in the bag and pump may be air or any other suitable fluid,
gaseous or liquid, and when air is used an inlet valve may be provided in con-
nection with the pump to admit air to make up for any slight leakage...
In the modification, in which the apparatus does not rotate, the strainer plates:
are fixed horizontally across the pulp vat, and at a little distance beneath them
there is fixed a frame covered with the impermeable flexible material. The pump
communicates with the space under the flexible cover, which space is otherwise
closed, and the discharge duct for the pulp communicates with the space between
the flexible cover and the strainer plates.
And in order that our said Invention and the manner of performing the same
may be properly understood we hereunto append a Sheet of explanatory Drawings
to be hereinafter referred to, and representing pulp straining apparatus as made
with our improvements. In these Drawings the same reference numerals are used
to mark the same or like parts wherever they are repeated.
Figures 1 and 2 on the accompanying Sheet of Drawings are longitudinal and
transverse vertical sections of our improved rotating pulp strainer. The strainer
casing 5, which is of the usual square form, is made with hollow trunnions 6, 7, as
formerly, which trunnions pass through stuffing boxes 8, 9, in the ends of the
vat 10, the one 6 at one end serving for the exit of the strained pulp into the
service box 11, whilst that 7 at the other end passes through a stuffing box 12 at
the end of a short bent pipe 13 communicating with the interior of the pump 14.
The pump is by preference of a kind having a plunger 15 working through a
stuffing box, and moved by a rotating crank shaft 16 driven in any convenient
way. Instead of the plunger pump a diaphragm pump may be employed, the
diaphragm consisting of a strong flexible material, such as vulcanised rubber com-
bined with a woven fabric. The trunnion 7 has fixed on it the usual spurwheel 17,
by means of which the strainer casing 5 is made to rotate.
The trunnion 7 connected with the pump 14 communicates inside the strainer
casing 5 with the interior of a bag or cover 18 made of an impermeable material,
such as vulcanised rubber combined with a woven fabric, this bag or cover being
held by and distended over a suitable framing 19, 20, fixed inside of the strainer
casing 5, which framing may be of wood or inetal, or of metal and wood combined.
The end furthest from the trunnion 7 is closed by a plate 21, but the bag 18 might
be extended over this end if found desirable. The framing and bag 18 present a
square form with rounded corners, as seen in cross section. Inside of the bag 18 there
is by preference fixed a closed shell or box 22 of wood or other suitable material
for the purpose of occupying the central part and diminishing the quantity of fluid
acted on by the pump, the end 23 of this box nearest the pump being tapered and
rounded. It is conveniently formed by fixing boards 22 between the longitudinal
corner pieces 20 of the frame carrying the bag 18. The spaces between the boards

page_text: or sides 22 of the box and the bag may be varied, but we believe that good results
will be obtained when the spaces taper from about 2 inches near the pump end to
inches at the other end.
Figures 3 and 4 are longitudinal and transverse vertical sections of our improved.
flat or non-rotating pulp strainer. The vat 24 is of a long shallow rectangular
form and the strainer plates 25 are fixed horizontally across it. A sheet 18 of an
impermeable flexible material, such as vulcanised rubber combined with a woven
fabric, is fixed horizontally across at a little distance below the strainer plates 25;
and in a manner to leave a thin space beneath it and the bottom 26 of the vat.
The pump pipe 13 is connected to the space under the flexible cover 18, which
space is otherwise closed, and the discharge duct 27 for the pulp communicates with
the space between the flexible cover 18 and the strainer plates. 25.
Having thus particularly described our said Invention and the manner of per-
forming the same, we have to state that we do not restrict ourselves to the precise
details herein described or delineated, but that what we believe to be novel and
original.and claim as the Invention secured to us by and in terms of the hereinbefore
in part recited Letters Patent is,—
The improved construction of pulp straining apparatus in which an impermeable
flexible material in the form of a sheet, cover, or bag, is interposed between a fluid
acted on by a pump and the pulp within or between the strainer plates, substantially
as herein before described.
In witness whereof, we, the said John Wood and Robert Wood, have hereunto
set our hands and seals, this Twenty-fourth day of February, in the year of
our Lord One thousand eight hundred and eighty.
Witness,
EDMUND HUNT,
Patent Agent,
Glasgow.
;
JOHN WOOD.
(L.S.)
ROBERT WOOD. (L.S.)