Improvements in Digesters for Treating Fish Offal.
Year: 1898

page_text: Date of Application, 1st Nov., 1898-Accepted, 10th Dec., 1898
Improvements in Digesters for Treating Fish Offal.
THOMAS HERBERT WYMONDE, Vancouver, British Columbia, Canada,
Gentleman, do hereby declare the nature of this invention and in what manner
the same is to be performed, to be particularly described and ascertained in and
by the following statement:-
My invention relates to improvements in an apparatus for treating fish offal;
and it consists in a closed vessel for subjecting the offal to a cooking agency, and
of expressing the moisture therefrom by steam-pressure; such cooking and
expressing being effected while the matter is kept in constant agitation by
agitators arranged in the vessel.
The agitation not only assists in cooking but also greatly facilitates in
seperating the moisture from the solids; the said agitation being the essential
feature of my improvement.
The object of my apparatus is to provide a means whereby the residue from fish
canneries, and other residuary offal, may be utilized and converted into their
respective marketable products, and to effect such work in a very cheap and
effective manner.
I attain this object by the mechanism illustrated in the accompanying drawing,
in which:
Fig. 1 is a vertical section of my apparatus.
Fig. 2 is a sectional plan of the same, on the line a a, and
Fig. 3 shows a sectional detail of the bottom of the digester, and the means
for supporting the grid, on which the matters being treated, is deposited.
Similar numerals designate corresponding parts in the several views.
The body 10 is a cylindrical vessel closed at each end by the dish-shaped
ends 11.
Suitably supported on an annular rim 12, above the dished bottom 11 is a
perforated bottom or grid 13. This grid is preferably made in sections, for con-
venience in putting it in position; and it is supported at its centre by cross-
ties 14. This structure requires to be of sufficient strength to support the weight
of the load superadded to the pressure of steam intended to be employed.
Securely fixed to the centre of the grid 13 is a step 15; and resting in this and
passing upwards through the centre of the vessel, and journalled in a packing
gland 16 at the top is a shaft 17. This shaft 17 is arranged to be turned at
comparatively a slow speed, by the gears 18 and 19, communicating with the
shaft 20. The beveled pinion 19 is loosely mounted on the shaft 20, and is
thrown in and out of contact by the clutch 21, slidably mounted on the same
shaft. Secured to the shaft 17, within the closed vessel, and arranged spirally
thereon, are agitating blades 22. These agitating blades 22 are placed at an
oblique plane, so that as they are passed round in the direction of the arrow
the offal will be agitated and constantly lifted upward, and thus loosened for
the steam to percolate through the entire mass; and, when the digester is
intended to be emptied, by reversing the movement of the shaft 17 the blades 22

page_text: will depress the matters treated, and force them from the closable opening 23.
The closure for the opening 23 is arranged to fit so that its inner wall will be
flush with the inner shell of the cylinder 10. This provides that no matters will
be allowed to lodge therein and escape the intermingling movement caused by
the blades 22.
24 indicates a closable opening in the top shell or end 11, for the introduction
of the offal.
A safety-valve pipe 25 is provided to guard against a strain greater than the
digester will stand with safety; a steam-pressure gauge pipe 26 is also provided
to show the pressure employed.
The steam pressure is introduced by the pipes 27 and 28 at the top and
bottom, respectively; and to assist in permeating the mass at its greatest density,
pipes are introduced through the shell 10 at intervals, on a plane just above the
grid 13 as 29. These pipes 29 may be increased in number according to the
requirements of the matters being treated.
30 indicates the pipe for drawing off the oil and aqueous matters that have
been ejected from the mass treated.
The digester is supported at a suitable elevation by the lugs 31, which lugs
must rest on a strong frame. Thus, by having the digester so poised, the matters
treated can be handled very cheaply, as in emptying and recharging the stuff
will gravitate to and from the same.
In handling large quantities of offal, it is intended to have a number of the
digesters placed in line, on the same plane, so that the shaft 20 may pass over
the entire lot and thus operate the whole plant of digesters.
In the operation of my invention, the opening 23 is closed tight, and the
digester is charged or filled through the opening 24; the said opening is then
closed tight. The agitators are put in motion in the direction of the arrow, and
the steam is turned on by the top and bottom pipes 27 and 28, and by the side
pipes 29, until the entire mass is cooked, when the pipes 28 and 29 are closed,
and extra pressure is added through the pipe 27. This will express the oil and
aqueous matters from the whole, which oil and water will pass through the
grid 13 to the depending basin 11, whence it is drawn off to suitable tanks by
the pipe 30.
When the expressing has been completed, the vents 23 and 24 are opened, and
the agitators are reversed. This will force the residue through the opening 23
in a very rapid and efficient manner.
It is shown from the foregoing that my improved digester is well adapted to
perform the work for which it was designed. The application of the agitators
shows a decided advantage over a vessel without that assistant, for treating all
semi-liquid matters, as the agitators insure a universal cooking to the whole
mass, besides preventing the matters from clogging and thus insuring more
perfect work.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is: -
1. A digester consisting of a cylindrical closable body, having a foraminous
bottom or grid arranged near the lower end thereof, a shaft supported on the
grid and passing upward through a gland in the top end, agitating blades
secured to the said shaft, the same being arranged obliquely and extending
radially to proximity with the inner shell of the closed vessel, and means for
rotating the said shaft, as and for the purposes specified.
2. In combination with a closed vessel having a closable opening at the top
and a like opening near its bottom, the latter opening being arranged above and
in proximity to a grid, a shaft made to turn within the centre of the closed vessel,
agitators arranged spirally on said shaft, and projecting radially therefrom, as
specified.

page_text: 3. In a digester for extracting the oil and aqueous matters from fish or other
offal, in combination with the closable vessel, the same being in cylindrical form,
a shaft arranged to turn in the centre o: same, agitator conveyers on said shaft,
the blades thereof radiating towards the shell of the vessel, and made to lift the
stuff upwards when turned in one direction, and depress it when turned the other
way, as and for the purposes specified.
I
1000