IMPROVEMENTS IN THE PROCESS AND APPARATUS FOR TREATING WOOD FOR THE Manufacture of PULP FOR PAPER
Year: 1872

page_text: LETTERS PATENT to Frederick Delacourt Blyth, of Fenchurch Street,
in the City of London, Merchant, and Anthony Gapper Southby,
of New Inn, Strand, in the County of Middlesex, Civil Engineer,
for the Invention of "IMPROVEMENTS IN THE PROCESS AND APPARATUS FOR
TREATING WOOD FOR THE Manufacture of PULP FOR PAPER."
Sealed the 8th October 1872, and dated the 14th August 1872.
PROVISIONAL SPECIFICATION left by the said Frederick Delacourt
Blyth and Anthony Gapper Southby at the Office of the Com-
missioners of Patents, with their Petition, on the 14th August
1872.
We, FREDERICK DELACOURT BLYTII, of Fenchurch Street, in the City
of London, Merchant, and ANTHONY GAPPER SOUTHBY, of New Inn,
Strand, in the County of Middlesex, Civil Engineer, do hereby declare
the nature of the said Invention for "IMPROVEMENTS IN THE PROCESS AND
APPARATUS FOR TREATING WOOD FOR THE MANUFACTURE OF PULP FOR PAPER," to
be as follows, that is to say:—
We are aware that for the manufacture of pulp suitable for paper-
making from wood, Letters Patent have been obtained for boiling the

page_text: same in a solution of alkali, at such a temperature as will produce a
pressure of from ninety to one hundred and eighty-five pounds to the
square inch. This process however has been found to be defective,
inasmuch as there is a loss of the alkali contained in that portion of
the solution not absorbed by the wood which becomes so contaminated
by the agglutinating constituents of the wood which have been dissolved
in it by the heat as to become unfit for use over again.
Letters Patent have also been obtained for alleged improvements
stated to consist in saturating the wood or other vegetable substance
to be converted into pulp with an alkaline or an acid solution, and 1
after drawing off the surplus solution submitting the wood or other
vegetable substance so saturated to a high degree of heat, videlicet,
about 300° Fahrenheit, the heat being applied externally to the vessel
containing the wood.
But this process as described will not produce the desired effect, the 1
material operated on is liable to be charred, and the operation is un-
certain in its results.
The defects above indicated are remedied by our improved process, by
which the wood is saturated with a solution of the quantity of alkali
necessary to render the agglutinating constituents of the wood freely 2
soluble in water and no more, and the heat necessary for effecting the
conversion is conveyed by the direct action of high-pressure steam, by
which means a large saving is effected, not only in the caustic alkali,
but also in the fuel and time employed.
In carrying out our process we first steep the wood cut into small a
pieces in a strong alkaline solution until it is saturated and has absorbed
a sufficient quantity of alkali to render the agglutinating constituents
soluble in water, after exposure to the necessary temperature. The
solution is used hot, but when we employ a close vessel the temperature
must not be raised sufficiently to render the agglutinating constituents &
freely soluble; this operation is effected in some cases in the vessel in
which the wood is afterwards to be treated by steam, (herein-after styled
the steam heating vessel) in which case the liquid is drawn off from the
wood before the steam heating process is applied by means of introduced
steam. In some cases we saturate the wood in another vessel or steeping a
tank, and when saturated remove it into the steam heating vessel; we
prefer to do this in cages or trucks hercin-after described, allowing them

page_text: to drain when the wood is saturated, and then placing them or emptying
them into the steam heating vessel.
In carrying out the steam heating process we subject the wood to
the direct action of steam at a sufficiently high pressure to produce a
5 temperature of between 320° and 390° Fahrenheit according to the
nature of the wood and strength of the alkaline solution employed,
after which operation the agglutinating constituents of the wood will
be found to have been rendered freely soluble and will leave the fibre
or pulp ready for washing.
e
The steam heating vessel which we use for heating the wood after
being drained from the excess of solution is a cylinder with an opening
at one end to introduce the wood, and an opening at or near the other
end to withdraw it therefrom, both openings being covered with steam-
tight covers, so fastened on as to sustain the pressure; or the wood may
be placed in cages or trucks with perforated bottoms, sides, and covers.
and lowered or run into the cylinder, in which case one end only
need be removeable, and it may be placed perpendicularly, horizontally,
or otherwise as may be judged most convenient; or the cylinder may
bo made to revolve preferably on trunnions, the steam being admitted
through the axis, in which case also an opening at one end only is
necessary.
We prefer to admit the steam into the steam heating vessel by means
of a perforated pipe or pipes passing through or nearly through the
mass of wood from one end to the other of the cylinder.
We produce the steam for the above operation preferably in a separate
boiler made of tubes with external flues, herein-after styled the steam
generator.
i
We prefer using two, three, or more steam heating vessels acting in.
combination with one steam generator, and in order to economiso heat
and make the operation continuous, we admit the steam contained in
the first vessel after the steam heating process has been completed
therein, into the second vessel in order to commence the heating of the
saturated wood, and when the temperature is equalised in the first and
second vessels we use the remainder of the steam to heat the steeping
liquor in the third and fourth vessels or in the steeping tank, and so
on continuously, by which a large saving of fuel, labour, and time is:
affected

page_text: Further, when the steeping process is performed in the steam heating
vessel (in which case we prefer to heat it under slight pressure), the
boiling solution contained in the first vessel is conducted after the
steeping process is completed into the second vessel, and so on in like
manner, adding each time the quantity of alkaline solution necessary 6
to replace that taken up by the steeping process in the previous
vessel.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Frederick Delacourt Blyth and Anthony Gapper
Southby in the Great Scal Patent Office on the 14th February
1873.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, FREDERICK
DELACOURT BLYTII, of Fenchurch Street, in the City of London, Mer-
chant, and ANTHONY GAPPER SOUTHBY, of New Inn, Strand, in the
County of Middlesex, Civil Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Fourteenth day of August, in the year
of our Lord One thousand eight hundred and seventy-two, in the thirty-
sixth year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto us, the said Frederick Delacourt Blyth and Anthony:
Gapper Southby, Her special licence that us, the said Frederick Dela-
court Blyth and Anthony Gapper Southby, our executors, adminis-
trators, and assigns, or such others as wc, the said Frederick Delacourt
Blyth and Anthony Gapper Southby, our executors, administrators, 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 THE PROCESS AND
APPARATUS FOR TREATING WOOD FOR THE MANUFACTURE OF PULP FOR PAPER,"
upon the condition (amongst others) that we, the said Frederick Dela-
court Blyth and Anthony Gapper Southby, our executors or adminis-
trators, by an instrument in writing under our, or their, or one of their
hands and seals, should particularly describe and ascertain the nature
of the said Invention, and in what manner the same was to be performed,

page_text: 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 we, the said Frederick Delacourt Blyth and
Anthony Gapper Southby, do hereby declare the nature of our said
Invention, and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following state-
ment:-
We are aware that for the manufacture of pulp suitable for paper-
making from wood Letters Patent have been obtained for boiling the
same in a solution of alkali at such a temperature as will produce a
pressure of from ninety to one hundred and eighty-five pounds to the
square inch. This process however has been found to be defective,
inasmuch as there is a loss of alkali contained in that portion of the
solution not absorbed by the wood, which becomes so contaminated by
the agglutinating constituents of the wood which have been dissolved in
it by the heat as to become unfit for use over again.
Letters Patent have also been obtained for alleged improvements stated
to consist in saturating the wood or other vegetable substance to be
converted into pulp with an alkaline or an acid solution, and after
drawing off the surplus solution submitting the wood or other vegetable
substance so saturated to a high degree of heat, videlicet, about 300°
Fahrenheit, the heat being applied externally to the vessel containing
the wood.
But this process, as described, will not produce the desired effect,
the material operated on is liable to be charred, and the operation is
uncertain in its results.
The defects above indicated are remedied by our improved process,
by which the wood is saturated with a solution of the quantity of
alkali necessary to render the agglutinating constituents of the wood
freely soluble in water, and no more, and the heat necessary for effecting
the conversion is conveyed by the direct action of high-pressure steam,
by which means a large saving is effected, not only in the caustic alkali,
but also in the fuel and time employed.
In carrying out our process we first steep the wood cut into small
pieces in a strong alkaline solution until it is saturated and has absorbed
a sufficient quantity alkali to render the agglutinating constituents

page_text: soluble in water after exposure to the necessary temperature. The
solution is used hot, but when we employ a close vessel the temperaturo
must not be raised sufficiently to render the agglutinating constituents
freely soluble ; this operation is effected in some cases in the vessel
in which the wood is afterwards to be treated by steam (herein-after
styled the steam heating vessel), in which case the liquid is drawn off
from the wood before the steam heating process is applied by means of
introduced steam. In some cases we saturate the wood in another
vessel or steeping tank, and when saturated remove it into the steam
heating vessel. We prefer to do this in cages or trucks, hercin-after
described, allowing them to drain when the wood is saturated, and
then placing them in or emptying them into the steam heating
vessel.
In carrying out the steam heating process we subject the wood to
the direct action of steam at a sufficiently high pressure to produce a
temperature of between 320° and 390° Fahrenheit according to the
nature of the wood and strength of the alkaline solution employed.
After which operation the agglutinating constituents of the wood will
be found to have been rendered freely soluble, and will leave the fibre
or pulp ready for washing.
The stoam heating vessel which we use for heating the wood after
being drained from the excess of solution is a cylinder with an
opening at one end to introduce the wood, and an opening at or near
the other end to withdraw it therefrom, both openings being covered
with steam-tight covers so fastened on as to sustain the pressure; or
the wood may be placed in cages or trucks with perforated bottoms,
sidos, and covers, and lowered or run into the cylinder, in which caso
one end only need be removeable, and it may be placed perpendicularly,
horizontally, or otherwise, as may be judged most convenient, or the
cylinder may be made to revolve, preferably on trunnions, the steam
being admitted through the axis, in which case also an opening at one
end only is necessary.
We sometimes admit the steam into the steam beating vessel by
means of a perforated pipe or pipes passing through or nearly through
the mass of wood from one end to the other of the cylinder.
We produce the steam for the above operation preferably in a separate
boiler made of tubes with external flues, hercin-after styled the steam
Fonunior

page_text: We prefer using 2, 3, or more steam heating vessels acting in comp
bination with one steam generator, and in order to economize that, and.
make the operation continuous, we admit the steam contained in the
first vessel after the steam heating process has been completed therein
into the second vessel in order to commence the heating of the saturated
wood, and when the temperature is equalized in the first and second
vessels we use the remainder of the steam to heat the steeping liquor
in the third and fourth vessels, or in the steeping tank, and so on
continuously, by which a large saving of fuel, labour, and time is
effected.
Further when the steeping process is performed in the steam
heating vessel (in which case we prefer to heat it under slight pressure)
the boiling solution contained in the first vessel is conducted after tho
steeping process is completed into the second vessel, and so on in
like manner, adding each time the quantity of alkaline solution neces
sary to replace that taken up by the steeping process in the previous
vessel.
C
Having thus described the nature of our Invention, we will now
proceed to describe the best means we are acquainted with for carrying
the same into effect by reference to the accompanying Drawing, which
shews one of the simplest forms of apparatus we employ."
'
In this Drawing A is a steam heating vessel or cylinder of wrought
iron, closed at both ends, and made of sufficient strength to sustain
the necessary pressure. At the top of this cylinder a wrought-iron
5 ring is rivetted round a man-hole with a cover B also of wrought iron,
screwed into it. with a steam-tight joint. One mode which answers
well for making this joint is to turn V grooves in the faces of the cover
and ring opposite one another, and to lay in them a hoop of copper
tube or wire lined on the inside with a layer of wood pulp itself. At
O the side of, the cylinder close to the bottom is a man-hole and cover O
which may be made like the upper one or similar to that in use for
steam boilers. On the bottom of the cylinder is fixed a false bottom Ę
of iron perforated all over with small holes, and at the top there is a
perforated ring E³ to prevent the chips choking the steam pipe and air
5 cock I. A pipe and cocks F admit the steam either to the top of
the steam heating vessel above the perforate ring E², or through the
bottom below the false bottom E, and sometimes it is caused to pass
through or partially through the mass of wood from either end of the

page_text: cylinder by means of a perforated pipe or pipes. A pipe and cock G
also connect the bottom of the cylinder below the false bottom E with
the reservoir H for the steeping solution fixed at a higher level. Each
cylinder is provided with a draw-off cock J, a pressure guage, and a
water guage.
In working this apparatus the man-hole cover at the bottom of the
steam licating vessel A is fixed in place, and the vessel is filled as full as
possible with the chips of wood, such as those cut by any of the ordinary
machines used for that purpose. The top cover B is screwed in tight
by means of a bar put through the handles, the steeping solution is
then run in from the reservoir H. The necessary strength of the
steeping solution of caustic alkali we find to vary greatly with the
nature of the wood and the thickness of the chips to be treated. Thin
chips absorb much less liquid than thick ones, and therefore require a
stronger steeping solution, and vice versa, so also with regard to the
different species, ages, and dryness of the woods. Green or young wood
require less alkali than seasoned or old wood, and trees containing much
ṛcsinous or agglutinating matters require more alkali than those con-
taining less of such matters. We have found to answer well for white
pine a strength of 1½ lbs. to the gallon of water. While filling the
steam heating vessel with the solution we allow the air to escape by an
air cock I above the perforated ring at the top of the cylinder, the fob
or froth which forms we also allow to escape through the same outlet,
and to avoid waste we conduct it by means of a pipe to the top of the
reservoir H, and when the cylinder is quite full of lye the air cock and
lye cock are turned off, steam is then admitted from the steam generator
under the false bottom, and when preferred through a perforated pipe or
pipes, and the pressure may be raised to not more than 40 lbs. to the
square inch, for the purpose of expediting the saturation. The steeping
is continued until the chips of wood are saturated; the time required
for this operation will vary with the nature of the wood and thickness
of the chips treated, we have found about one hour under pressure to
answer for thin pine chips.
When the process of steeping is completed the steam is turned on to
the top of the cylinder, and the solution not absorbed by the chips is a
blown back into the reservoir, ample time being allowed for the chips
to drain before greatly raising the pressure in the cylinder, and the
liquor cock being gradually closed to avoid loss of steam. When the

page_text: cylinder is drained the liquor cock is turned off and the steam turned
on full from a steam boiler capable of supplying steam at the required
pressure. Howard's steam boiler, called the safety boiler, answers well
for this purpose. The pressure of the steam is raised till the wood is
heated throughout to from 370 to 390 degrees Fahrenheit; a good
method of ascertaining when the heat is uniform throughout is to turn
off the steam for a short time, and watch the rate at which the pressure
decreases in the cylinder by means of the pressure guage. As soon as
all the wood is raised to or above the required degree of heat the process
is finished. The liquor or condensed steam is drawn off by the cock J,
the steam is blown off, and may be used for heating the lye in the
reservoir, and for other purposes, the man-hole covers at the top and
bottom of the cylinder are removed, and the chips withdrawn. The wood
will then be in a fit state to undergo the ordinary operations necessary
for manufacturing boiled fibre or pulp into paper.
Care should be taken in these processes that the steam used should be
as free from air as possible, we prefer therefore to boil the water before
pumping it into the steam boiler.
A simple modification of the above apparatus consists in balancing the
steam heating vessel in trunnions when an opening at one end only is
necessary, the steam pipe may then pass through one trunnion, the
liquor pipe through the other, each being provided with union joints at
the axis of the trunnions as is well understood. Or the steam heating
vessel may rotate horizontally on journals, the connections being made
as in the case of the vessel moving on trunnions herein-before described,
one or more openings will then be required in the side of the vessel, and
a perforated false bottom, or a perforated pipe must be fixed along one
side for draining it, and the steam may be admitted through perforations
in a pipe or pipes passing through from end to end of the cylinder. This
modification is well adapted for utilizing the refuse from wood working
machinery. Or the cylinder may be laid horizontally with one remove-
able end, and in this case we prefer to pack the wood in covered trucks
made of perforated sheet or plaited hoop iron or wire, of a size to fit
easily into the cylinder, and made to run in on wheels connecting the
liquor, steam, and air pipes and cocks, with perforated pipes running
from end to end at the top and bottom of the cylinder. The general
working of the apparatus with these three modifications of the -steam
licating vessel is the same as in the first arrangement described.

page_text: We have hercin-before described different forms of steam heating
vessels used separately, but instead of one cylinder and steeping tank
we prefer using several of such cylinders connected together in a series
forming a circuit, we then connect the steam pipe and cock of each of
the cylinders with a main steam pipe from the steam generator, and also
each steam pipe with a second pipe and necessary cock connecting them
all together, and we also connect the liquor pipes with one main liquor
pipe. In working this apparatus when the process of steeping the wood
in the first cylinder is finished, as herein-before described, we blow the
surplus heated liquor not absorbed by the wood into the second cylinder
of the series, which in the meantime has been filled with chips, and the
alkali and water required to replace that absorbed in the first. We
allow the air and fob or froth to escape either into a reservoir, or where
a sufficient number of cylinders constitute the series, through the upper
steam pipe into another of them. We find that for some woods an
amount of alkali equal to 15 lbs. of good commercial solid caustic soda
to the cwt. of chips will answer, but, as before stated, the quality
depends upon circumstances. When the chips in the first cylinder arc
drained the high-pressure steam is let in as before described till the heat
is raised to the converting temperature, and after the converting process
is completed we allow sufficient of the steam contained in the first
cylinder to pass into the second cylinder until the pressure is equal in
both cylinders, using any remaining steam for boiling the liquor in
another cylinder, which in the meantime has been filled ready to receive
it. When the operation in the first cylinder is finished the second takes
the place of the first in the process, and the third of the second, and so
on in rotation. When four cylinders are used in a series one may be
blowing off steam, emptying and filling; the next may be draining and
heating for the conversion, and the other two undergoing the steeping
process.
We have described a general arrangement of connections by pipes and
cocks, and a succession of operations, but these will vary according to
the number of cylinders and relative time required for the different
processes, pressure regulators, three-way cocks, and steam traps may be
used to prevent mistakes and facilitate the work.
When the method of steeping the chips in one vessel and converting
them in another is employed we use an open steeping tank filled with
a solution of caustic alkali of the strength herein-before described. We

page_text: place the chips of wood in cages made of perforated sheet iron or-
of wire, or hoop iron, plaited like a basket, with covers to fasten
down, and sufficiently heavy to sink in the liquor when filled with
chips, lowering and raising, them by a crane into and out of the steeping.
tank.
'
The steam heating vessels may be constructed like those described for
the first, second, and fourth modifications; if like the first the soaked
chips may be tipped or shovelled in at the top opening, and after fixing
the cover in place letting in the steam at the top of the cylinder and
opening the passage to the receiver or steeping tank in the bottom to
allow all the air to escape, which may be ascertained by bubbles ceasing
to rise in the tank. When the converting process is finished we use the
steam for heating up the liquor in the steeping tank, or when more.
cylinders than one are employed for heating up the others.
second modification of cylinder be used we prefer to make the cover
the whole; diameter of the cylinder for greater facility in filling and
emptying, the operations being the same as those before described; or›
we use a cylinder like the first, except that the cover is of the same
diameter as the cylinder, and that it has only one opening. In this case
we make the steeping cages to fit easily into the cylinder. A form of
this apparatus which answers well is to make the steeping tank in the
shape of a portion of a cylinder, with a crane fixed in the centre and two
or three of the steam heating vessels arranged at the same radius from
the centre as the tank. In working this apparatus, when the wood in
one of the cages is saturated in the tank the cage is raised by the crane, .
swung round over one of the open cylinders, and lowered into it, when.
the converting process proceeds as before described, and when finished
the steam contained in the cylinder is let into another cylinder which
has been prepared in like manner till the pressure is equal in both,
when the remaining steam may be used to heat the steeping tank or for
commencing the heating of a third cylinder prepared in like manner,
and so on in rotation.
"
Having now described the nature of our said Invention, and the best
means we are acquainted with for carrying the same into effect, we wish
it to be understood that we do not confine ourselves to the special
forms described; but what we claim is,―
-
Firstly. The employment of high-pressure steam applied directly to
wood previously made to absorb the required-amount of caustic alkaline

page_text: solution in order to heat it to the temperature necessary to render the
agglutinating constituents thereof freely soluble in water, substantially
as herein-before described.
Secondly. The combination of the steam heating vessel, including its
modifications, with its connections and the alkaline solution reservoir, by
which the steeping solution is saved for re-employment, as licrein-before
described.
Thirdly. The combination of tlic steam heating vessel including its
modification with its connections and the wood steeping tank, as
herein-before described.
Fourthly. The arrangement and combination of a series of two,
three, or more steam heating vessels with their connections, and either.
with the wood steeping tank or with or without the alkaline solution
reservoir, as hiercin-before described, whereby the operations are rendered
continuous, and a large portion of the steam is re-employed, thus
effecting a considerable saving of fuel and time.
In witness whereof, we, the said Frederick Delacourt Blyth and
Anthony Gapper Southby, have hereunto set our hands and
scals, this Fourteenth day of February, in the year of our Lord
One thousand eight hundred and seventy-three.
FRED". D. BLYTH.
(L.S.)
A. GAPPER SOUTHBY. (L.S.)