IMPROVEMENTS IN THE MANUFACTURE OF PAPER-PULP, AND IN APPARATUS THEREFOR
Year: 1884

page_text: I WILLIAM ROBERT LAKE of the firm of Haseltine Lake & C° Patent Agents
Southampton Buildings in the County of Middlesex do hereby declare the nature
of my invention for "IMPROVEMENTS IN THE MANUFACTURE OF PAPER-PULP, AND
IN APPARATUS THEREFOR and in what manner the same is to be performed, to
be particularly described and ascertained in and by the following statement:-
27
This invention relates to the production of fibre, suitable for paper-making, from
wood, and to apparatus therefor. The said invention has for its objects to reduce
the cost of producing the wood pulp and to facilitate the operation of such
production; to regain to a large extent the acids and chemicals which are used in
the boiling process, whereby the cost of production is reduced; to simplify the
work of production by rendering the process more largely automatic than has
heretofore been the case; to so construct the digester used in this process, as to
simplify the operation of constructing the same and to exclude the steam from
direct contact with the contents of the digester; and, finally, to provide the digester
with an improved lining which shall meet the peculiar requirements of this
improved digester.
To the above ends, the said invention comprises the peculiar and novel con-
struction of the digester, the improved method by which the gases are withdrawn
from the digester automatically, and the novel arrangement of the lining, all as
hereinafter described.
In order that the invention may be fully understood, I will describe it with
reference to the accompanying drawings, in which
Figure 1 is a sectional view of the digester, showing the same connected with
the steam-dome.
Figure 2 is a sectional view of the steam-dome, showing the blow-off pipe
connected with a separate condenser.
Figure 3 is a transverse vertical section of the improved digester.
Figure 4 is a sectional view of one of the upper joints in detached position.
Figure 5 is a similar view of one of the lower joints...

page_text: Figure 6 is a vertical section of the digester, showing the improved lining
applied thereto.
Figures 7 and 8 are detached sectional views, respectively, of the upper and
lower joints, showing the methods of applying the lining.
In the various processes now in use for disintegrating the fibre of wood or other
substances, by boiling the same under pressure, sulphurous acid is used to dissolve
the resinous, albuminous, or other matter by which the fibres are enclosed and held
together.
1
The liquid in which the fibre is boiled consists of water containing from one to
to four per cent of acid, preferably sulphurous, to which magnesia or lime is added
in varying proportions. In this liquid the fibre is submerged and is heated by
steam in a jacketed non-corrosive netal-lined boiler, sufficient space being left in
the upper part of the boiler or digester to form a steam-space. During the process
of boiling gases are formed in considerable quantities, which, by the absorption of
oxygen from the steam, the water, and the fibrous material, form sulphuric acid
which is liable to injure the wood or other fibre by blackening the same.
It has,
therefore, been necessary heretofore to blow off the steam and gases from time to
time, (requiring considerable time and attention to do this at the proper time) the
gases so blown off being lost. Another difficulty consisted in the sudden expansion
of the gases by which the pressure in the digester was increased on top of the
wood or other fibre under treatment; thus preventing the free circulation of heat
through the liquid. To avoid all of these difficulties and also to prevent the loss of
chemicals, I connect the steam-space of the digester with a worn or condenser
surrounded by cold water and controlled either by a valve, or, as is shown in the
drawings, with any one of the well known forms of steam-traps, by which the
condensed liquid is automatically withdrawn without diminishing the steam-
pressure in the digester. When the process of boiling the fibre is completed, the
steam and gases are blown off, and to utilize the chemicals contained therein.
I provide a separate condenser consisting of a worm placed in a large tank of water,
and I connect this tank of water with the digester so that the water heated by the
escaping steam and gas can be readily used for washing the digester. The
condensed acid is conducted to a stirrer by which the condensed liquid is
incorporated with any desired base. In place of thus incorporating the sulphurous
liquid it may be drawn into any suitable receptacle and preserved for further use.
In the drawings A indicates the digester or vertical jacketed and non-corrosive
metal-lined boiler, B a perforated false bottom, C the steam-dome and D a steam-
pipe by which the interior of the digester is supplied with steam.
This pipe D
enters the bottom of the digester (the joint being made by a suitable flange) and
the end of the steam-pipe is provided with a suitable head by which the steam is
distributed laterally and equally in all directions.
E indicates the steam-pipe by which steam is admitted into the sections of the
steam-jacket which surround the digester, F a pipe which connects the various
sections of the steam-jacket with the steam-gauge f, f¹ the steam or pressure
gauge which is connected with the interior of the digester and G the discharge-pipe
by which the contents of the digester are blown out. This discharge-pipe is
provided with a gate-valve g. To prevent any fibre from entering the pipe G
during the boiling process, the plug-valve g¹ is placed in the discharge-pipe and
rests against a suitable seat in such a manner as to close the pipe and thus prevent
the entrance of libre into the pipe from the digester.
H indicates a worm-condenser which consists of a coil of pipe placed in a tank
into which cold water is conveyed, and this coil serves to condense the vapors or
gases from the digester. h is a pipe which connects the condenser with the
steam-dome of the digester, and this pipe may be provided with a valve so as to
control the flow of vapor from the digester to the condenser. h' is a trap which
may be of any of the various forms of such devices, the object of the said trap is to
prevent the escape of steam while permitting the passage of condensed vapour.

page_text: I is the pipe by which the steam and gases are blown off from the condenser and
digester when desired.
Referring now to Figure 2, it will be seen that the blow off I is connected with
the coil of the pipe K which is placed within the tank L, the latter being supplied
with water by the pipe 1. The tank L is connected with the digester by the
pipe so that the water from the tank can be readily run into the digester, and
this water being heated by the vapor and gases passing through the coil K, is
conveyed into the digester for the purpose of washing it.
When the steam and sulphurous vapor are to be blown off from the digester the
valve i is opened and the steam and vapour pass through the coil K, wherein they
are condensed and the liquid of condensation flows into the receiver M. Any base,
preferably magnesia, is placed in the receiver and this base and the liquid are
stirred together by the stirrer m to facilitate the mixture of the acid with the base.
By this improved process and apparatus the wood or other fibre is subjected to
the steam-heat in the usual manner, the steam-pressure being gradually raised, but
the accumulation of gas-pressure, heretofore occurring, is avoided; the circulation
is more rapid, and all parts of the fibre in the digester are more thoroughly
subjected to the action of the heat and liquor than heretofore. The formation of
sulphuric acid by the condensation of the gas is also avoided, and the burning or
blackening of the fibre is prevented. All the chemicals not taken up by the
resinous and fibrous material are regained; the time required to boil the liquid and
the care, attention labor and degree of skill required in conducting the boiling are
materially reduced while the product is more uniform and of superior quality as
compared with that produced by preceding processes.
In order to subject the wood fibre to a more thorough treatment by the chemicals
a constant circulation of the chemicals from the bottom of the digester out of the
same is established and then into the same through its top from whence the
chemicals pass downward through the wood The chemicals after leaving the bottom
of the digester and before entering its top are brought into contact and mixed
with steam, whereby they are heated and injected into the upper part of the
digester. The arrangement whereby this result is accomplished is shown in
Figure 1, in which N designates a pipe which extends vertically outside of, and
parallel with, the digester. At its upper end this pipe has a branch which enters
the top or steam-space of the digester, while at its lower end the pipe N is
provided with a cylindrical chamber n¹ from which a branch n² extends laterally
and vertically into the digester, through its bottom and terminates in a T-head n³
which lies just below the perforated bottom B of the digester. o designates a
steam-pipe the upper end of which enters the bottom of the chamber n' and which
is provided with a valve o'. Now, when the valve o' is opened, the steam, flowing
up through the chamber n', will act as an injector drawing the chemicals out of
the bottom of the digester through the branch n² into the chamber ', then forcing
them up through the pipe N where they are heated by the steam, and thence forcing
them into the top of the digester, through the branch n, from whence they again
descend through the wood.
Digesters used in the manufacture of paper-pulp are necessarily of great size,
and, as they have to stand high internal pressure, they should be built very
strongly. As heretofore constructed the building of these digesters has been n
very difficult and costly operation owing to their size and to the fact that they
have been built up of as few sections as possible in order to lessen the amount of
leakage resulting from high internal pressure. By this improved construction these
large digesters may be cheaply and yet strongly built and this we accomplish in the
manner which we will now describe.
O designates the outer and P the inner shell of the digester, which enclose the
annular space p*, constituting the steam-jacket. The outer shell O is composed of
the annular sections p', p', p, p, while the inner section is composed of the
sections q, q, q, q, similar to and concentric with the outer sections. These sections
.✓

page_text: are of boiler-iron. Q, Q, Q, designate a number of iron rings arranged in pairs
and each of L-shape; the straight sides of each pair of rings being placed in
contact. These rings are held together by rivets or bolts passing vertically
through the ends of the rings, as shown in Figures 4 and 5. The plates O and P
are secured to the rings Q, by bolts or rivets which pass horizontally through
the rings and plates, as shown in Figures 4 and 5. Between the rings Q the
plates O, P, are strengthened by rivets passing horizontally through the plates
and steam-space p* and surrounded cach, within the steam-space, by a sleeve by
which the ends of the rivets may be upset without injuring the plates.
The lower ring Q is not L-shaped but is plain, as shown in Figure 1, while the
upper ring of the upper pair of rings is formed to correspond with the oblique
direction of the shoulder or hood of the digester. The rings Q' by which the hood
is joined to the cap R, are each formed with a series of recesses in which the
bolts are removably secured; each of said bolts being hinged at its lower end to
a ring, as shown in Figure 3, so that the cap may be readily removed.
It will thus be seen that the largest sized digesters may be readily set up in
sections and that when so set up they are perfectly strong. It will also be seen
that the steam does not come into direct contact with the contents of the digester,
but flows through the steam-space between the annular walls of the digester. The
sections of the digester are of such size as to admit of ready transportation, while
the rings may be of any convenient dimensions. A suitable metallic liuing
(preferably copper) is to be placed on the inside of the inner shell.
I have also devised an improved lining which is particularly adapted to the
requirements of this digester; The said lining is shown at S and is of any suitable
material preferably copper or lead. The lining covers the entire interior of the
digester, but as the digester is itself built up of sections, the lining is applied to
each section separately and these sections are afterwards united so as to form a
continuous lining..
I employ two methods of uniting the lining sections; that shown in Figure 7
and also shewn in Figure 8.
In Figure 7 the lining-sections are each made to overlap the upper and lower
edges of the shell-section, as at 8, and when the shell-sections are being put
together the surplus portion of the lining is bent over upon the meeting faces of
the sections; thereby forming a tight joint between the sections so as to prevent
leakage.
In Figure S the upper surplus edge S¹ is bevelled, the under edge is turned
inward, and a suitable metal is run in between the two edges, as shown at S², thus
forming a tight joint and preventing leakage. These two methods may be used
either separately or in conjunction, as is shown in Figure 1. The lining extends
from the cap to the outlet of the digester.
Having now particularly described and ascertained the nature of the said
invention, and in what manner the same is to be performed I declare that what
I claim is
First. The improved process for treating wood and similar fibre for paper-making,
the same consisting in boiling the material in a solution containing sulphurous acid
and under pressure in a digester the upper portion of which is connected with a
condenser by which the gases expelled are condensed so as to prevent accumulation
or change, as described.
Second. The process herein described for regaining the chemicals used in the
boiling of wood and other fibres, the same consisting in passing the gases through a
condenser or condensers connected with the digester, as described.
Third. The combination with the digester A, of the condenser H constructed to
condense the gases during the process of boiling, as described.
Fourth. The combination with a digester, of a condenser connected with the
steam-space of the digester and constructed to condense the gases during the
process of boiling, as described.

page_text: Fifth. The combination with the digester and the blow-off pipe I, of the tank L
and the condenser K constructed to condense the gases and heat the water, as, and
for the purposes, described.
Sixth. The combination with the digester A, of the blow-off pipe I, the valve i,
the coil K, and the tank L connected with the digester by the pipe l, as described.
Seventh The combination with the digester, constructed and arranged sub-
stantially as set forth, of the pipe N having the branch n, the chamber n¹ having
the T-headed branch n³, and the valved steam-pipe o, substantially as described.
Eighth. A digester having double walls made in sections and united section to
section and wall to wall by rings, substantially as described.
Ninth. The combination with the shell-sections O, P, of the rings Q to which
the said sections are bolted, substantially as described.
Tenth The combination with the sections p, p, q, the hood and the cap, of the
rings Q2, and the bolts, substantially as described.
Eleventh. The combination with the digester constructed as described and
provided with the cap and hood, of the rings Q3, 6, and the bolts hung to said
ring and arranged to enter recesses in the ring Q³, substantially as described.
Twelfth. The combination with the shells O, P composed of the sections p¹, p³,
q, the hood, and the cap, of the rings Q, Q, the bolts r, r³, and the rivets r³ with
the sleeves, constructed and arranged substantially as described.
Thirteenth. The combination with a digester composed of separate sections, of a
lining formed also in separate sections, each of which overlaps the edges of the shell
sections, the said surplus portions being united so as to form tight joints and
constitute a continuous lining, as set forth.
Dated this 19th day of Santamber 182A
HASELTINE, LAKE & Co.,
For the Applicant.