IMPROVEMENTS IN APPARATUS EMPLOYED IN CONVERTING ESPARTO, STRAW, WOOD, AND OTHER SIMILAR SUBSTANCES INTO PULP
Year: 1872

page_text: LETTERS PATENT to Charles Stevenson, of Milngavie, in the County
of Dumbarton, North Britain, for the Invention of "IMPROVEMENTS
IN APPARATUS EMPLOYED IN CONVERTING ESPARTO, STRAW, WOOD, AND
OTHER SIMILAR SUBSTANCES INTO PULP."
Scaled the 16th August 1872, and dated the 5th April 1872.
PROVISIONAL SPECIFICATION left by the said Charles Stevenson at
the Office of the Commissioners of Patents, with his Petition, on
the 5th April 1872.
I, CHARLES STEVENSON, of Milngavie, in the County of Dumbarton,
North Britain, do hereby declare the nature of the said Invention of
"IMPROVEMENTS IN APPARATUS EMPLOYED IN CONVERTING ESPARTO, STRAW, WOOD,
AND OTHER SIMILAR SUBSTANCES INTO PULP," to be as follows, that is to
say:
'This Invention which relates to improvements in that class of boilers
employed in converting esparto, straw, wood, and other similar substances
into pulp to be used in the manufacture of paper, consists in arranging
within the close shell of the boiler and at its upper end a perforated disc

page_text: or plate corresponding in dimensions to the internal diameter of the
boiler. The perforated disc or plate is formed with a doorway through
which the charge is introduced into the lower part of the boiler, and it
is attached to the lower extremity of a vertical rod or spindle and
counterpoised by means of a weighted cord or chain passed over a pulley
and attached to the upper end of the rod or spindle. When a charge of
esparto, straw, wood, or other pulp-making substance has been introduced
into the boiler, the perforated plate is allowed to descend thereon,
thereby packing it downwards towards the bottom of the boiler, and thus
allowing of a larger charge of material being placed in the boiler for one
operation than obtains under existing arrangements. By means of this
arrangement of boiler economy is effected in the quantity of caustic ley
employed in boiling the material into pulp, and a saving of time is also
effected in evaporating the boiling liquor, the steam proceeding from
which escapes through the perforations in the plate.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Charles Stevenson in the Great Seal Patent Office
on the 4th October 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CHARLES
STEVENSON, of Milngavie, in the County of Dumbarton, North Britain,
send greeting.
WHEREAS Her most. Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Fifth day of April, in the year of
our Lord One thousand eight hundred and seventy-two, in the 35th
year of Her reign, did, for Herself, Her heirs and successors, give and
grant unto me, the said Charles Stevenson, Her special license that I,
the said Charles Stevenson, my executors, administrators, and assigns,
or such others as I, the said Charles Stevenson, my executors, adminis-
trators, and assigns, should at any time agree with, and no others, from
time to time and at all times thereafter during the term therein
expressed, should and lawfully might make, use, exercise, and vend,
within the United Kingdom of Great Britain and Ireland, the Channel
Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN APPARATUS
EMPLOYED IN CONVERTING ESPARTO, STRAW, WOOD, AND OTHER SIMILAR SUBSTANCES

page_text: INTO PULP," upon the condition (amongst others) that I, the said Charles
Stevenson, by an instrument in writing under my hand and seal, should
particularly describe and ascertain the nature of the said Invention, and
in what manner the same was to be performed, and cause the same to.
be filed in the Great Seal Patent Office within six calendar months next
and immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Charles Stevenson, do hereby declare
the nature of my said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the
following statement, reference being had to the accompanying Drawings,
and to the letters and figures marked thereon, that is to say:-
My said Invention which relates to improvements in that class of
boilers employed in converting esparto, straw, wood, and other similar
substances into pulp to be used in the manufacture of paper, consists
in arranging within the close shell of the boiler and at its upper end a
perforated disc or plate corresponding in dimensions to the internal
diameter of the boiler. The perforated disc or plate is formed with a
doorway through which the charge is introduced into the lower part of
the boiler, and it is attached to the lower extremity of a vertical rod or
spindle and counterpoised by means of a weighted cord or chain passed
over a pulley and attached to the upper end of the rod or spindle. When
a charge of esparto, straw, wood, or other pulp-making substance has
been introduced into the boiler, the perforated plate is allowed to descend
thereon, thereby packing it downwards towards the bottom of the boiler,
and thus allowing of a larger charge of material being placed in the
boiler for one operation than obtains under existing arrangements. By
means of this arrangement of boiler economy is effected in the quantity
of caustic ley employed in boiling the material into pulp, and a saving
of time is also effected in evaporating the boiling liquor, the steam
proceeding from which escapes through the perforations in the plate.
And in order that my said Invention may be properly understood, I
now proceed more particularly to set forth the system, mode, or manner
in or under which the same is or may be used or practically carried into
effect, that is to say :-
On the Sheet of Drawings hereunto appended, Figure 1 is a vertical
section, and Figure 2 a horizontal section of a boiler for converting

page_text: esparto, straw, wood, and other similar substances into pulp, as con-
structed in accordance with one modification of this Invention.
Within the close sheel A of the boiler, and towards its upper end, a
curved disc or plate B corresponding in dimensions to the internal
diameter of the boiler A is situated, and which is perforated with a
number of holes, as more particularly seen at Figure 2. The plate B is
suspended from the lower extremity of a vertical rod or spindle C, passed
through a gland D formed on the close shell A of the boiler, as shewn
at Figure 1, and the upper extremity of the rod or spindle C is attached
to one end of a cord or chain E, which is passed over a pulley F, and is
provided with weights G sufficient to counterpoise the weight of the
perforated disc or plate B. A weight may or may not be placed on the
perforated disc or plate B at that part marked H, Figure 2, in order
to counteract any tendency in the disc or plate to hang unevenly from
the suspending rod or spindle C, on account of the said rod or spindle
being situate somewhat out of the centre of the disc or plate B, as shewn
at Figure 2; or two suspending rods connected together by a cross piece
or link may be employed to sustain the weight of the disc or plate B.
A doorway I is formed in the disc or plate B at that part immediately
beneath the ordinary doorway J of the boiler, and through these door-
ways the esparto, straw, wood, or other pulp-making substance is
introduced into the interior of the boiler. At the centre of the boiler
a vomit pipe K is situated, the lower extremity of which rests on the
perforated plate or disc L, its upper end being terminated at a short
distance from the top of the boiler, as shewn at Figure 1. At the
interior of the pipe K, a steam pipe M is placed as shewn, and which
communicates with the main pipe N, connected to a boiler for generating
steam. The disc or plate B is drawn up close to the top of the boiler
previous to introducing a charge of esparto, straw, wood, or other pulp-
making substance, and a quantity of caustic ley sufficient for one boiling
operation having been charged thereinto through the doorways J and I,
these doorways are then closed by their respective lids or covers, and the
perforated plate or disc B is allowed to descend on the esparto, straw,
wood, or other substance, thereby packing it downwards towards the
perforated plate or dise L, and thus allowing of a larger charge of
material being boiled at one operation than obtains in existing arrange-
ments of boilers of the class illustrated on the accompanying Drawings.
The caustic ley is maintained at the temperature requisite to boil the

page_text: substance, being operated upon by a jet of high pressure steam conducted
through the pipes N and M, and the caustic ley having percolated
through the substance being boiled, flows through the perforations in
the disc or plate L and collects in the bottom of the boiler, it is then
blown or vomited by the pressure of the steam up through the pipe K,
and flowing on to the upper side of the disc or plate B again percolates
through the perforations therein, and the substance being boiled, so that
it passes again to the bottom of the boiler from which it is again caused
to circulate upwards as indicated by the arrows, and so on during the
whole operation of boiling the substance into pulp, which having been
effected, the liquor is drawn off through the tap or cock O, and the pulp
removed through the doorways I, and J.
Under another arrangement of boiler constructed in accordance with
this Invention, a close cover A is attached at its circumference to the
moveable perforated disc or or plate B, as shewn at x on the vertical
section at Figure 3 of the Drawings. A space C is left between the
close top A and perforated disc or plate B, into which the upper end of
the vomit pipe D is introduced, and the said pipe is in this instance
formed with a telescopic joint, as shewn, so as to allow the upper part
of the pipe to ascend and descend correspondingly with the upward
or downward movement of the perforated disc or plate B and close
top A.
.
Steam is conducted to the boiler shewn at Figure 3 by a pipe E situate
underneath the boiler, and the caustic ley as it collects in the bottom of
the boiler is blown or vomited by the pressure of the jet of steam pro-
ceeding from the pipe E up through the pipe D, being thence discharged
into the space C, and flowing through the perforations in the disc or
plate B, percolates downwards through the esparto, straw, wood, or other
similar substance being boiled into pulp. In charging the boiler now
under reference, the close cover A. and perforated disc or plate B are
drawn up clear out of the boiler and after the charge of material has
been introduced into the boiler, the cover A with the perforated disc or
plate B is again allowed to descend thereon, thereby packing the said
charge downwards towards the perforated disc or plate L.
In lieu of arranging the boiler with a moveable perforated disc or
plate at the upper part thereof, as herein-before described and shewn at
Figures 1 and 2, or at Figure 3 of the Drawings, the telescopic vomit
pipe A is provided with a series of perforated pipes B radiating from the

page_text: First. The employment of a perforated movable plate in connection
with boilers wherein straw, esparto, wood, or other similar substance is
reduced to pulp, as herein-before described and shewn at Figures 1
and 2 on the annexed Sheet of Drawings.
Second. Attaching a close cover to the movable perforated disc or
plate, as herein-before described and shewn at Figure 3 of the Drawings.
Third. The employment of a series of perforated pipes as a substitute
for the perforated discs or plate, as herein-before described and shewn at
Figure 4 of the Drawings.
In witness whereof, I, the said Charles Stevenson, have hereunto
set my hand and seal, this Third day of October, One thousand
eight hundred and seventy-two.
CHARLES STEVENSON. (L.S.)