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Nßv. l2, 1946.
J. .1. DE LA RozA, sRr
Filed March 29, 1944
" 1 ` luw.
Patented Nov. 12, 1’946
Joaquin J. de la Roza, Sr., New York, N. Y.
Application March 29, 1944, Serial No. 528,537
2 Claims.
This invention relates to improvements in a
digester unit and refers more particularly to an
assembly consisting ci an inner rotatable diges
tion vessel supported within an outer station
ary vessel, the inner vessel having an inlet open
ing for introduction of the material to be treated
and an outlet for discharge of the stock after
digestion. In the annular space between the
inner and outer vessels is circulated a heating
medium for accurately controlling the tempera
ture within the inner vessel.
Between the vessels at their ends are seals
which prevent communication between the con
tents of the inner vessel and the jacket and auto
(Cl. 92>--18)
, practice which normally seriously aiîects the
homogeneity of the mass; the action of the tubu
lar screw conveyor preventing migration of the
material longitudinally of the chamber.
In the accompanying drawing which forms a
part of the instant speciñcation, and is to be
read in conjunction therewith and in which like
reference numerals are used to indicate like
parts in the various views,
Fig. 1 is a sectional side view of a digester
in which the chemicaltreating and mechanical
reduction sections are combined in a single ves
Fig. 2 is a fragmentary view oi a two-vessel
matically compensate for differences in elcnga 15 unit in which the mechanical reduction is per
tion caused by uneven heating.
formed in a separate vessel.
The novelty resides primarily in providing aReferring first to the digestion unit shown in
tubular screw conveyor digester in one section
Fig. l, an outer stationary cylindrical vessel lilv
and grinding means in a separate section of the
is supported upon foundations li
means of
same vessel or in a separate vessel for mechani 20 supports i2. At the ends of the vessel i@ are
cally redu'cing the material undergoing`diges
flanges i3 to which are bolted covers iti and i5.
An opening it in cover it serves as an inlet for
The digester unit is particularly adapted for
material charged through pipe il'. In cover it
digestion of iibrous substances in the presence of
is an opening i8 through which the material is
chemicals at elevated temperatures for the pro
discharged after digestion. A discharge pipe i9 is
duction oi uniformly high grade cellulose pulps.
The digester oiîers 'facilities for uniformly
treating fibrous material for a longer period of
bolted to the opening.
Within the stationary vessel le is a concentric
cylindrical vessel of smaller diameter 29 which
time in a continuous operation, utilizing a'much
has a common axis with the outer vessel. The
shorter vessel than is necessary for the same re 30 inner vessel which encloses the digestion space
sults when a tubular screw conveyor or mechani
cal reduction is not employed.`
is rotatable within the outer stationary vessel.
The inner vessel is supported upon sets ci ñanged
rollers 2i supported Within the outer stationary
There is provided in a single vessel means for
digesting fibrous substances in the presence of
vessel. Pairs of the rollers are oiîset somewhat
chemicals at high temperature and simultaneous 35 from the low point of the inner digestion vessel
ly mechanically reducing the bundles of ñber.
and are hanged to roll upon traclss or rings 22
A further advantage of the design is the :fas
which surround the periphery or" the vessel at its
tening of the conveyor screw to the internal wall
ends and at necessary intervals along' its length
of the digesting vessel, thereby eliminating the
where the vessel needs support.
objectional eüect of a rotating screw which 40
As a source of power for rotating the inner
scrapes and damages the ñbre.
vessel there is shown a motor 29 supported with
'in addition, the digestion unit combines facili
its gear transmission upon a foundation 25.
ties for more uniformly and effectively impreg
Upon the shaft of the motor is mounted a pin
nating the fibrous material with chemical liquor
ion 25 which meshes with a second pinion 2li on
while mechanically breaking up the ñbrous bun 45 stub shaft ‘27. Gear E8 on the stub shaft meshes
dles and disseminate more eiîectively and sepa
with a ring gear 29 surrounding and ?lxedly at
rate the incrustations from the ñber.
tached tothe shell of the inner vessel. Suitable
The digester unit eliminates to a great extent
stuñing boxes surround shaft '2l' where it enters
by-passing of undigested portions of the material .
the auxiliary housing iii which surrounds gear
undergoing treatment and substantially` prevent
28 and communicates with the annular space
ing insuñcient or inadequate treatment of por
between the two vessels. .a :duid medium cir
tions of the digesting mass, thereby increasing
uniformity of the product.
through pipe 3i and is discharged through pipe
it eliminates irregularities in the product pro
duced by stopping and starting of the digester, a
nularr rings 3S which form annular cylinders 34.
culated in the annular space is introduced
On the inner face of ñanges i3 are an
2,410,964 `
Reciprocatable in cylinders 3l are'seal rings 35
it is discharged through the perforations in plate
~whose inner ends contact the outer faces of
flanges 20a of the inner rotating cylinder as
suring a pressure-tight seal between the inner
rotating vessel and the> outer stationary vessel
regardless of elongation differences of the re
spective vessels due to diñerential heating. Pres
sure behind seal rings 35 for effecting the proper
degree of contact between the rings and the'
40 which are of a size which will permit ready
' passage of the treated mass, but prevents passage
of the impacting elements. _After passage
through plate 40 the pulp is discharged through
opening I8 and pipe I9. After leaving the digester ‘
the pulp mass may be treated in any desirable
The operation with respect to the digester unit
flange 20a is produced either by fluid pressure 10 shown in Fig. 2 is similar to that shown in'Fig. 1 '
with the exception v that during the digesting
or by suitable compression springs, details of
_period the mass passes through two separate di
which form no part of the present invention.
The digestion space within the inner Vessel lis
gestion zones, onelimited to substantially chemi
divided into sections by a perforated plate 38.
cal treatment and the other primarily to mechan
ical reduction. The two separate stages in Fig. 2
Within the section to the left of this partition
are joined by transfer pipe 4I. The details of '
is shown the vanes of a, continuous screw 31. In
the section to the right of partition 36 is a com
both the chemical digester and mechanical di-Í
gester of Fig. 2 'is diagrammatically shown ~with
partment equipped with a liner of material re
many of the parts eliminated in the interest of
sistant to impacting elements shown diagram
matically at 39. 'I‘hese impacting elements may 20 simplicity as their details ‘are more clearly shown
and described in the single digester unit shown in
be> tubes, balls or rods or any type of objects which
Fig. 1.
tumble about in the compartment and serve to
break down or reduce mechanically the material
For controlling the temperature of digestion
undergoing digestion. A second perforated plate Y within the inner vessel -in both the single unit
4D prevents the impacting elements fromY escaping 25 and in the double unit a ñuid heating medium is
from the compartment but permits passage of the
circulated in the annular space surrounding the
inner vessel through pipes 3| and discharged
broken up fibrous material_from the mechanical
through pipes 32. This fluid medium is preferably
reduction compartment into the discharge pipe
I8 of the dige'ster.
steam where heating is desired, but may be any
In the modified type of digester unit shown in 30 suitable fluid such as oil or its derivatives or other
Fig. 2 the single concentric vessels have been . heating ñuids. Where refrigeration is desirable
replaced by a pair of concentric vessels connected
in the digestion ofany material a, brine may be
by a transfer pipe 4l. Instead of separating the ,
circulated or other type of refrigerant may be
circulated through the annular jacket.
inner vessel into -two sections by the perforated
plate 36, onedigester includes the section in which
While the digester unit has been described in.
connection withthe treatment of fibrous mate
thev chemical treatment _of the fibrous material
is performed, the succeeding digesting vessel cor
rials,l it may be employed asl-,well in the digestion
responds to the compartment for mechanically
of any substances where the material -is to be
chemically treated and mechanically disinte
reducing the chemically treated mass identical in
grated and the temperatures of digestion ac->`
construction to the compartment to the right of
the perforated partition in 36 in Fig. 1. By num
c curately maintained.
bering corresponding parts of the digester Iunits
It is contemplated also that inthe treatmentshown in Figs.- 1 and 2 with corresponding nu
of fibrous substances there may be interposed be
merals best indicates the similarities between the
tween the'mechanical and ,chemical stages as
structural elements. In Fig. 2 the outer sta 45 shown in Fig. 2, a deliquefying treatment as by
tionary casing is shown at l0, the inner rotating
pressing vor rolling.~
' ‘ .
vessel at 20. The supports and drying mechanism
while'in has> been proved preferable to menne '
is, of course, identical. Attached to the inner
slightly the digesters so that drainage will readily e
wall .of the inner vessel is a continuous screw 31
take place, it is a feature of the- digester'units
which serves to advance the material as the vessel
that they need not be placed at any appreciable
slant or inclination in order to produce the desired `
Referring» to the operation of the digester
forward movement or advancement of the digest
shown in Fig. 1 material to _be digested is intro
ing mass as this is taken care of'by the effect of
" duced through pipes- I1 and inlet opening I6 in
screw 31. The screw flights also have'the effect
' . the cover l 4 of the stationary digester. This inlet 55 of uniformly mixing the mass with thetreating
lopening communicates with a chamber in the'
liquor. By ,attaching the internal screw io`the
inlet end of the stationary vessel which is in
wall of the inner vessel, the objectionable effectl‘of
a' rotating screw which'scrapes and damages fiberV
alignment with vthe open end of the inner rotating
vessel. 'Rotation of the irmer _vessel causes the
material to be picked up by the nights 31 of the
. screw attached to the inner wall of the vessel
advancing material slowly longitudinally of the
is avoided.
From lche foregoing it win be seenzthàt the m
vention is one Well adapted to attainall of thel
ends and objects herein set forth together with
other advantages- which areobvioual and which> ~_
vessel as it rotates. The digestion liquor is intro
are inherent to thestructure.
duced to the material prior to its introduction.
As many possible embodiments `may 4be made _ ’
As a result of the breaking down of the material 65
resulting from the reaction of the digestion
liquor and the mechanical effect of the tumbling
as it advances through the vessel, on arrival at
perforated plate 36 its particle size is sufllciently
of the invention without departing from the'scope
thereof, it is to be' lunderstood that >all 'matter
herein set forth orY shown in the accompanying
drawing is to be interpreted as illustrative and
small to pass the perforations in the plate. In 70 not in a limiting sense.
Having thus described my invention, I claim:
the compartment or section of the inner vessel
I.' A continuous multistage digester. unit com
to the right of plate 36 the mass is brought in
prising substantially horizontal 1‘ rotatable inner
intimate contact with the impacting elements 39
and stationary outer imperforate vessels having
where it is mechanically reduced and disinte
grated to the desired amount. As the pulp stock 75 fluid-tight seals therebetween and means for cir
culating a fluid medium in the annular space be
tween the Vessels, the former of said vessels en
closing a digestion space, a perforated partition
dividing the digestion space into separate sections,
said perforated partition adapted for passing
digested material therethrough, an open screw
añixed to the inner wall of one section for ad
vancing material, impacting objects Within the
other section of the digestion space, and inlet and '
discharge pipes at opposite ends of the digestion
2. A digester unit comprising substantially
horizontal concentric cylindrical vessels having a
common axis and a sealed annular space there
between, means for circulating a. fluid medium
through the annular space, the inner vessel rotat
able within the outer stationary vessel, said inner
vessel enclosing the digestion space, a perforate
partition dividing the digestion space into sep
arate sections, inlet and discharge pipes at oppo
site ends of the digestion space, _an open screw
aflixed to the inner wall of one section for ad
vancing the material introduced thereto upon
rotation of the inner vessel, and mechanical im
pacting objects Within the other section of the
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