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Jan. 7, 1947.
J. c. F. c. RICHTER
Filed July 30‘, 1945
H for»? y
Patented Jan. 7, '1947
Johan Christoffer Fredrik Carl Richter, Oslo,
Norway, assignor to Aktiebolaget Kamyr, Karl-
l stad, Sweden, a company of Sweden
Application July 30, 1945, Serial No. 607,696
In Norway May 2, 1944
4 Claims.
(Cl. 92-7)
The present invention relates to an apparatus
duits may be connected to the pump and to the
heat exchanger.
for heating- and for controlling the temperature
of the contents of a continuously operating di
By allowing liquor to circulate alternately
gester for digestion of ?brous material, of the type
through the several circulation conduits at suit
able intervals of ‘time, and by supplying to the
which is provided at one end with a device for
feeding raw material into the digester, and at
its other end with a device for discharging the
digested product, and through which digester the
contents thereof, that is to say, the material
liquor or removing from the same the necessary
uor, thus move continuously from the feeding end
to the ‘discharge end. The contents of the di
gester may, but need not necessarily,vbe main
tained at a pressure which exceeds the VELDOI‘i'?
zation pressure of the digestion liquor at the 15
circumference, thus causing it to ?ow in various
amount of heat, the desired temperature control,
that is, heating or cooling, may easily be effected
in the digester,‘ and by alternately introducing
charged into the digester, and the digestion liq~ 10 the circulating liquor from various points of the
maximum temperature prevailing in the digester.
directions through the digester transversely there
of, an as uniform heating or cooling as possible
is obtained over the entire cross section of the
digester. The supply of the required amount of
heat to the circulating liquor may be e?ected
either directly, as for instance by introducing
It is the purpose of the present invention to
provide an apparatus which renders it possible
fresh steam into the liquor. or indirectly through
the heat exchanger, and by means of the latter
easily to attain and maintain the desired tem
perature or temperatures at desired points or in 20 it is also possible to remove heat from the circu
lating liquor and thus from the digester.
predetermined zones between the feeding end and
The accompanying drawing illustrates by way
the discharge end of the digester, in such man
of example and schematically an apparatus ac~
ner that at such points or zones the tempera
cording to the present invention. Fig. 1 is a, sche
ture becomes as uniform as possible over the
25 matic showing of the apparatus with a portion
entire cross section of the digester.
of the digester in axial section, and Fig. 2 shows
According to the present invention there are
schematically the apparatus with the digester in
connected to the digester, at a point between the
feeding end and the discharge end thereof, or
at several such points, two or more ‘circulation
conduits located outside the digester, in such
manner that the outlet or outlets from the di
gester of each circulation conduit, which outlet
cross section.
The circulating liquor is drawn through an out
30 let from the digester covered by a sieve I by a
circulation pump 2 which pumps it through a
heat exchanger 3 back to the digester through
an inlet 4, or several inlets, arranged diametrically
or outlets are suitably covered by a sieve pro
opposite the sieve I. The latter has suitably a
vided in the wall of the digester, and the inlet
or inlets into the digester of each circulation 35 peripheral extension of 120", since in such‘ case
the circulation liquor is distributed in the best
conduit are positioned substantially diametrical
possible manner over the entire cross section of
ly opposite to one another. The outlets and in
' the digester, as indicated by the arrows in Fig. 2.
lets of all circulation conduits are located in one
The digester is further provided with a similar
and the same transverse plane through the di
sieve 5 and an outlet diametrically opposite to the
gester, or substantially in such a plane, and the
l, and with an inlet 6 diametrically oppo
several circulation conduits are displaced, as far
site the inlet 4. ‘By a simple reversal of the di
as their outlets and inlets are concerned, rela
rection of flow by means of the slide 1 of a re
tively to one another around the circumference
versing valve, such reversal being indicated by
of the digester, preferably at an angular distance
the dotted lines in the drawing, the required
corresponding to 360° divided by the number of
equalization of the temperature over the cross
circulation conduits, that is to say, in such man~
section of the digester may be easily effected.
ner that the outlets as well as the inlets are
distributed at preferably equal angular distances
from one another around the circumference of'
the digester. The circulation conduits are con
nected with a pump and with a heat exchanger
or the like located outside the digester, by means
of a reversing valve of such construction that by
means of said valve any of the circulation con
_ In the position of the slide 1 of the valve that is
illustrated with full drawn lines in Figs. 1 and 2,
the pump 2 draws the circulating liquor from the
digester through the sieve I and forces it through
the heat exchanger 3 to the inlet or inlets 4. If
the slide 1 is moved to the position shown with
dotted lines, then the pump 2 draws the circu
lating liquor through the sieve 5 and forces it
through the heat exchanger 3 to the inlet or
inlets 6.
It is of course possible to use three
sieves, each having a peripheral extension of 120°,
and a corresponding number of inlets, but the
arrangement above described using two sieves l
and 5 has been found e?icient for practical pur
1. In an apparatus ‘for heating and control
ling the temperature in a continuously operat
ing digester for digesting ?brous material, the
combination of means for charging raw material
into the digester at one end thereof, means for
dischargingv digested product from the digester
at the other end thereof, at least two circulation
conduits located outside the digester and con~
In addition to supplying heat by the aid of a
nected to the digester at a point intermediate
heat exchanger, as'above described, it is also 10 the feeding end and the discharge'iend there
possible by means of a heat exchanger in a simi
of, each circulation conduit having its outlet from
lar circulation system at another stage of the
the digester and its inlet into the digester posi
digestion, for instance at a further point on the
tioned substantially diametrically opposite to one
path of travel of the mass through the digester,
another, the outlets and inlets of all circulation
to remove heat in order to lower the temperature
conduits being located substantially in one and
within a certain limited zone.
the same\,transverse plane through the digester,
In addition to effecting control of the tempera
ture by supplying or removing heat, the appara
tus according to the invention may, of course,
'be utilized for introducing into the digester,
simultaneously or separately, the chemicals that
the outlets and the inlets of the several circula
tion conduits being respectively spaced relatively
to one another around the circumference of said
20 digester, a pump, a heat exchanger, and a revers~
ing valve connecting said pump and said heat
exchanger to said circulation conduits in such
are required for the digestion, such as acid, al
kali, S02, and so forth. It is also possible by
‘means of the arrangement to remove, for in
tance, S02 from the digester, ‘by lowering the‘
pressure of the circulating liquor outside the
digester in order to partially free the liquor from
$02, after which the liquor is returned to the
manner that said conduits may be selectively con
nected to said pump and said heat exchanger by
means of said reversing valve.
2. An apparatus as defined in claim 1, wherein
the outlet from the digester of each circulation
conduit has a peripheral extension of 120° along
thecircumferenc f the digester.
It will be understoodthat the several circula
3. An apparatus‘ as de?ned in claim 1, wherein
tion conduits should preferably lie as nearly as
the outlet from the digester of each circulation
possible in one and the same plane asgfar as their
conduit is covered by a sieve in the wall of the
inlets into and outlets. from the digester are
'digester. I
concerned. Usually,_,however, digesters used for
4. An apparatus as de?ned in claim kit/herein
continuous digestion‘have a considerable length, 25 the outlets from the digester and the inlets into
such as twenty meters or more, between the feed
the digester of the several circulation conduits
ing end and the discharge end, and in view here- '
are respectively spaced at equal angular distances
of it‘ is, of course, of less importance if the in
from one another around the circumference of
lets and outlets of the several circulation con
duits lie at a distance of, say, one meter from
one another in the longitudinal direction of the
I claim:
the digester.
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