Improvements in Digesting Apparatus.
Year: 1891

page_text: Complete Specification Left, 8th Jan, 1902
Date of Application, 8th Apr., 1891
1000
Accepted, 5th Mor.
Mar 1802
PROVISIONAL SPECIFICATION.
Improvements in Digesting Apparatus.
I, WILLIAM HENRY MUNNS, of 106, 107, and 108, Victoria Chambers,
55 and 56 Chancery Lane, in the County of London, Patent Agent, do hereby
declare the nature of this invention (a communication to me from abroad by
Gustav Kaffenberger, of Cleveland, Ohio, U.S.A., Inventor,) to be as follows:-
This invention has reference to certain new and useful improvements in digesting
apparatus, and the invention comprises a conduit which has a receiving and a
discharge end Two valves are arranged near the discharge end of the conduit,
thus forming a chamber in the conduit between the valves. A second pair of
valves are arranged near the receiving end of the conduit, thus forming a chamber
in the conduit between them.
Suitable horizontal cylinders open at one end into each of the aforesaid chambers,
and are provided with pistons which reciprocate alternately in combination with
the valves, by suitable mechanism therefor provided.
W. H. MUNNS.
COMPLETE SPECIFICATION.
Improvements in Digesting Apparatus
I, WILLIAM HENRY MUNNS, of 106, 107, and 108 Victoria Chambers,
Chancery Lane, in the County of London, Patent Agent, do hereby declare
the nature of this invention (a communication to me from abroad by Gustav
Kaffenberger, of Cleveland, Ohio, U.S.A., Inventor,) and in what manner the same
is to be performed to be particularly described and ascertained in and by the.
following statement :-
Where material is to be subjected to a process of digestion or cooking or
diffusion, the general process usually employed may be briefly described as con-
sisting in putting the material into a vessel along with the liquor of treatment, and
when the material has been subjected to the action of the liquor for a sufficient
length of time emptying the vessel and then proceeding with a new charge, the
liquor being probably withdrawn or weakened or strengthened during the operation.
In some cases the operation will consist of a succession of steps-say in different
vessels whereby the material is subjected to the action, progressively, in the
operation of stronger liquor or liquors having superior capacity for action, the
general principle being that weak liquor can best attack the fresh raw material,
while stronger liquor must be employed upon the more resisting poorer
material.
The object of the present invention is to produce a digesting apparatus_in
which the process may be carried on in a practically continuous manner, the
raw material going into one end of the apparatus and coming out at the other end
in a substantially-continuous stream of progression.
The improvement will be readily understood from the following description,
taken in connection with the accompanying drawing, which is a vertical section of
a digesting apparatus exemplifying my invention. In the general description
which follows I will assume, as a mere example, that the material to be operated
upon is straw to be digested for paper-making purposes, other uses of the
system for purposes of digesting, cooking, or diffusion being then self-explaining.
In the drawing, A indicates a long pipe, whose course of direction may be as
DO27

page_text: desired vertical, horizontal, spiral, or what not; B, the receiving end of the pipe,
shown as provided with a hopper for the reception of the straw to be treated; C, a
valve at the receiving end of the pipe at the foot of the hopper; D, a valve in the
pipe near the receiving end after the valve C; E, a valve in the pipe after the
valve D and near that valve; F, the terminal or discharge end of the pipe; G, a
valve in the pipe near the discharge end; H, a valve in the pipe near the valve G
and before that valve; J, that portion of the pipe comprehended between the
valves E and H, this portion of the pipe constituting the digesting-chamber; K, a
chamber formed by that portion of the pipe between valves Dand E; L, a chamber
formed by that portion of the pipe between the valves G and H; M, a piston
working in a cylinder whose end is open to a chamber K N, a piston working in
a cylinder whose end is open to chamber L 0, a vent-pipe communicating with
chamber K through perforations which will permit the escape of vapours, but not
of straw, from chamber K; P, a valve in the vent-pipe; Q, a rotary cam-shaft
exemplifying means for operating the valves and pistons in proper order; R, a
rotary draining-bushing in the pipe just after the valve E; S, spiral vanes
projecting inwardly from this draining-bushing, whereby the rotary drainer
becomes a conveyer, which will tend to urge forward upon the mass of material
within the digesting-chamber; T, a heater; U, a pump to draw liquor from the
drainer through the heater and discharge it into the digesting-chamber J, further
along in the length of the digesting-chamber-say near its terminal at the valve H;
V, the liquor-pipe conveying the liquor from the drainer through the heater and
pump again to the digesting-chamber; W, a pipe to supply fresh liquor in
addition to the liquor which is withdrawn from the drainer; X, a pipe to supply
steam to the heater; Y, a pipe for the discharge of water for condensation from
the heater; Z, a pipe to admit liquor to the material at the receiving end of the
apparatus, this pipe being preferably connected to a pump which takes its supply
from liquor drained from material which has been discharged from the apparatus,
whereby such greatly-exhausted liquor as to heat or strength becomes used in the
treatment of the richest straw; a, à lever connecting the stem of valves E and H
with the stem of valves C; b, a lever on the stem of valve P; e, a tappet on the
stem of valve E, adapted, when valve E has closed, to open vent-valve P; d, the
connected stems of valves E and H; e, the connected stems of valves D and G;
f, cams on the cam-shaft Q for operating the valves and pistons, the two pistons
being also united by a common piston-rod; y, a worm to be continuously rotated,
engaging a worm-wheel on the drain-bushing R.
I have shown exemplifying mechanism for giving motion in proper time to all
the valves and pistons. The character of this meclianism is entirely immaterial to
my invention so long as it will give the proper motion to the parts, and, indeed, it
is not even necessary that there be any such uniting mechanism, as the separate
valves and pistons may be independently moved in proper order.
It will be noticed that the digesting-chamber J, when the valves are in the
position shown, extends from valve D to valve G. The digesting-chamber
throughout this entire length represents a large clear conduit to contain and pass
the material to be operated upon-say straw. Assume this entire digesting-
chamber to be full of straw and charged with hot cooking-liquor. Assume, further,
that the cooking temperature is such as to maintain comparatively high pressure in
the digesting-chamber. The walls of the apparatus must be strong enough to
resist this pressure. The rotation of the drain-bushing R tends to urge this mass
forward in the digester. Liquor which drains from the drain-bushing R goes
through the heater and becomes reheated and is pumped into the mass farther on
in the digester, fresh liquor being charged at W if needed to keep up the strength
of the liquor. In this way the mass in the digesting-chamber is being subjected to
the action of liquor moving through it in a direction backward through the
digester, and the mass of material has a tendency, by reason of the conveyer-
vanes S, to move forward in the digester, if such movement is possible. Material
near the initial end of the digester may be quite rich fresh material which has been

page_text: acted upon but a short time, while material near the terminal end may be said to
be thoroughly-digested material which has been a long time acted upon, having
passed through the length of the digester.
The liquor circulated by the pump U and reheated and strengthened is thus
moving through the mass of material from thoroughly-digested material to richer
and fresh material. The liquor as it proceeds through the mass becomes, of
course, more exhausted in strength or heat, but comes into action on material
of increasing richness, and consequently of less resistance to the liquor.
It will be noticed that piston N is up, the material in the digester thus occupying
also the cylinder-space under this piston. The material in the chamber Lis
digested material, as thoroughly digested as the apparatus is capable of, that
material having passed through the length of the digesting-chamber. Chamber K
is also full of material of the freshest character which is confined within the
apparatus. Assume fresh dry straw to be in the hopper B, into which it may be
delivered by any suitable form of carrier, the delivery being, if desired, continuous.
Now let valves E and H be closed, and then let vent-valve P be opened. This
cuts off the two chambers K and L from the balance of the digester-chamber, and
the pressure in chamber K relieves itself through the vent-pipe. Now let valves D
and G be opened and let both pistons move down. The downward movement of
piston N, in conjunction with the pressure in chamber L, has discharged some of
the contents of chamber L through open valve G and out of the digester. At the
same time the descent of piston M has enlarged the capacity of chamber K.
Valve C is to have been opened, and consequently straw from the hopper and
between the hopper and valve D will pass into chamber K to take possession
of the additional holding capacity resulting from the descent of piston M. The
new straw then passing into chamber K is charged with liquor pumped in
through pipe Z, and this liquor may, as before stated, be weak liquor drained
from material discharged from the digester, this weak liquor having to deal
immediately only with fresh, rich, low-resistance straw. Now let valves G and D
close and valve C also. Then let the vent-valve P be closed. Then let valves E
and H be opened. Chambers K and L have now become again portions of the
common digesting-chamber. Now let pistons M and N rise. Their motion will
make more room in chamber L and less room in chamber K, and the mass will thus
be forced forward in the digester from the point where piston M is compressing to
the point where piston N has provided additional room. The mass is also being
constantly urged forward in the digester by the conveyer-vanes S. The valve and
piston motions are continuously repeated in the manner indicated, and consequently
the straw will be moving constantly forward through the digester and passing out
at F in a practically constant stream. The length of the digester-conduit should
be such that the material in passing through it occupies at least that length of
time which is requisite to the proper digestion of the material.
With some kinds of material and with some lengths of conduit there will be no
need for the vanes S or any equivalent conveyer in the conduit, the actions of the
valves and pistons being sufficient to move the material forward, and again in
other cases the conveyer S would not only be needed, but it may be insufficient,
and more similar or equivalent conveyers may need to be distributed along the
length of the conduit to urge the material through the digester.
The liquor-circulating system illustrated is preferable in dealing with some
materials, but not in all cases. In some cases it will be sufficient if the injection
at Z be depended on and in other cases an injection through W. This injected
liquid going into the digester-chamber at any desired point or points may be found
preferable without circulation of liquid-that is to say, without withdrawal and
circulation of the same liquor the liquor of digestion being simply injected into
the mass and carried out with the digested mass, from which it may be subsequently
drained. It is to be understood, of course, that the digested material passing from
the outlet is to be subjected to any furthur treatment, as draining, washing,
grinding, etc., that may be called for.

page_text: It will be observed that the main principle of my improved digester rests in the
fact that the digester consists of three chambers A, K, and L, the latter two
forming, alternately, connected portions of chamber A. and portions entirely cut off
from chamber A, the pistons M and N serving as displacement agents for alternately
contracting and enlarging the holding capacity of chambers Kand L. It will be
further observed that while it is essential in the system to enlarge chamber K, so
as to permit that chamber to receive additional material, it is not essential that
chamber L shall be enlarged by means of a piston N or its equivalent. When
valve H is closed and valve G opened, then more or less of the contents of
chamber L will obviously leave chamber L by gra ity and by the out-blowing
effect of the pressure in the chamber. Therefore when valve G closes again the
chamber L, while its capacity has not been enlarged, will have become partially
emptied, so as to be capable, when valve H is opened again, of permitting forward
movement of the material in the digester. Therefore while displacing agent N is
useful it is not essential.
Having now particularly described and ascertained the nature of this my said
invention, and in what manner the same is to be performed, I declare that what
I claim is:
1. In a digester, the combination, substantially as set forth, of a conduit having
a receiving end and a discharge end, two valves near the discharge end of the
conduit forming a chamber in the conduit between the valves, a second pair of
valves near the receiving end of the conduit forming a chamber in the conduit
between them, a cylinder open to the chamber formed by said second pair of valves,
a displacing-piston in said cylinder, and a liquor-inlet to said conduit.
2. In a digester, the combination, substantially as set forth, of a conduit, a pair
of valves near the receiving end thereof, a second pair of valves near the discharge
end thereof, a cylinder at each pair of valves open to the chamber formed between
the valves of the pair, a displacing-piston in each cylinder, and a liquor-inlet to the
conduit.
3. In a digester, the combination, substantially as set forth, of a conduit, a pair
of valves, a cylinder, and a displacing piston near each end of the conduit, a
conveyer in the conduit between the two pairs of valves, and a liquor-inlet to the
conduit.
4. In a digester, the combination, substantially as set forth, of a conduit, a pair
of valves, a cylinder, and a displacing piston near each end of the conduit, a liquor-
inlet to and a liquor-outlet from the conduit between the two pairs of valves, and a
circulating-pump connected with said inlet and outlet.
5. In a digester, the combination, substantially as set forth, of a conduit, a pair
of valves, a cylinder, and a piston near the receiving end of the conduit, a pair of
valves near the discharge end of the conduit, and mechanism connecting and
arranged to operate the valves and piston.
Dated this 8th day of January 1892.