Improvements in Fish Offal Digesters, and Means for Supplying Offal to the same.
Year: 1898

page_text: Date of Application, 26th July, 1898-Accepted, 24th Sept., 1898
COMPLETE SPECIFICATION.
Improvements in Fish Offal Digesters, and Means for Supplying Offal
to the same.
THOMAS WATTS, Vancouver, British Columbia, Canada, Civil Engineer, 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;
The first part of my invention consists in means for passing the fish offal, by a
series of conveyors and carriers into tanks, whence it may be passed by gravity to
digesters; and the second part of this invention provides a means for extracting
the oil and gelatine from such. offal while in the digesters, whence the residue
will be carried away to receptacles, preparatory to being converted into guano cr
plant food.
The object of my invention is to provide a cheap and rapid means of treating
large quantities of fish and fish offal, and extracting the constituents therein
respectively, and preparing them for marketable products.
Reference being made to the accompanying drawing, in which—
Fig. 1 shows a plan of the general arrangement of my apparatus.
Fig. 2 is a vertical section of Fig. 1, taken on line a a; and,
Fig. 3 is an enlarged transverse sectional plan of the digester, taken on line 6b,
in the last figure.
In the said drawing, 10 indicates a conveyor chute arranged over hopper-
tanks 11. The offal is conveyed along the chute 10 by an endless device, which
is common to conveyers of this class; and in the chute 10, over each tank, is a
drop-door 12. These doors 12 are arranged over the centres of each tank, and
are provided with means of opening or closing them, at pleasure. The bottoms
of the tanks are sloping forward, as 13, and their forward sides are contracted
into chutes 14. These chutes 14 are provided with trap-doors 14ª, designed to rise
and fall vertically, by means of a rack 15 operated by a pinion 16, which is
fixed to a wheel-shaft 17.
The tanks 11 are so elevated that the matters deposited therein, through the
drop-doors 12, will pass to the chutes 14 by gravity. Pivotally secured to the
projecting lips of the chutes 14, are movable ducts 18. These ducts, when de-
pressed, communicate with openings 19, in the upper ends of vertically placed
digesters 20; and, when the chutes are elevated as shown by dotted lines in
Fig. 2, the openings 19 are sealed by detachable doors, or by any other means
that is found convenient.
As better shown in Figs. 2 and 3, each digester 20 is provided, at some dis-
tance from its conoidal bottom, with a sloping foraminous bottom 21, and this is
borne by an annular support 22 secured to the inner periphery of the digester,
and by cross-bars 23 supported by the same.
At the lower side of the sloping bottom 21, is an opening 24 in the shell of
the digester. This opening 24 is provided with means for making it steam tight,
for a purpose to appear later.

page_text: At the top of each digester is arranged a steam pipe 25, a pressure guage pipe 26,
and a safety valve vent 27. The two latter provide against too great a strain being
exercised within the digesters.
4
At the lower depending ends of the digesters are.arranged inlet pipes 28. These
pipes pass through the shells of the depending conoidal ends of the digesters,
beneath the perforated bottom 21, therein, and their inner ends curve upwards,
and are provided with baffles 29, which are designed to slip up and down on
upwardly projecting pins, over the mouths of the pipes 28.
These baffles 29 provide for steam being evenly distributed under the bottom
of the perforated grids 21; and, when the pressure is brought to bear from above,
as will be understood presently, the baffles will lie over the mouths of the pipes,
and prevent any matters passing therein.
1. I
At the lowest point of the depending ends of the digesters, are pipes 30. These
pipes are for the purpose of drawing off all moistures from the offal that is being
treated, which moisture will be in the form of oil, gelatine, and water.
The digesters are suitably supported in a frame A, and the hopper-tanks are
arranged at a suitable distance above the same, so that the offal in such tanks
will pass to the digesters by gravity through the trap. doors 14, when such doors
are opened as described above.
In the operation of my invention, the offal is brought along the chute 10 by
conveyers, and is dropped through the drop-doors 12 into the tanks 11. When
it is desirous to use but one tank and digester, the doors 12 are all closed except
the one in use. It is thus shown that one or as many of the tanks as desired
may be in use at the same time, to suit the requirements for disposing of the
offal.
By raising the trap doors 14ª the offal passes into the digesters, until they are
as full as desired, when the trap doors are closed, and the openings 19 in the
digesters are also closed tight, so that there can be little or no escape of steam.
Steam is then turned on by the pipes 25 and 28, until the entire mass has been
permeated and cooked, which usually occupies forty-five to sixty minutes accord-
ing to the steam pressure.
When the cooking process has been completed, the pressure is shut off from the
port 28, and the pressure is increased through the port 25. This will drive all
moisture downward through the mass and through the bottom 21, whence it is
driven off through the pipe 30 into condensing tanks to cool, when the oil will
be released from the gelatine and water and may be drawn off into tanks arranged
for its reception. After this the water is evaporated from the gelatine by heat,
and the oil and gelatine respectively may be refined and placed in convenient
marketable form.
After all moisture has been ejected from the mass in the digesters, as before
mentioned, the doors 24 are opened, and the residue is taken from the digesters,
when they will be ready for another charge. The residue is stored away to be
further treated for making plant food or guano.
As will be better understood from Fig. 1, to provide for a continuous operation
of the cooking and ejecting process, and at the same time to be economical in
the use of the steam agency, 'one or more of the digesters may be cooking the
offal, while the others are in some other stage of the operation-being emptied
or refilled.
It is thus shown that, although a great number of digesters may be in use at
once, the operation may so be arranged that a minimum of power will operate a
large plant successfully.
!
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 In an apparatus for handling and digesting fish offal, and for extracting the
marketable products therefrom, the combination of a series of hopper tanks 11.

page_text: having sloping 'bottoms, and contracted outlets at their lowest plane, and means
for depositing the offal into one, or more of them simultaneously, as specified;
of vertically slidable trap doors 14ª arranged in the said contracted outlets, means
for opening and for closing the same; of digesting tanks 20 having open-
ings 19 in their upper ends, arranged in proximity to the outlets in the
tanks 11, and movable ducts 18 pivoted to the projecting lips of the said outlets,
and designed to communicate with the openings in the digesters, whereby the
offal will be deposited therein, as set forth.
2-In an apparatus for handling, and for extracting the marketable products
from fish offal, the combination of a series of tanks 11, the same having forwardly
sloping bottoms, means for depositing the raw offal into said tanks, openings at
the lowest plane in the bottoms of said tanks, vertically slidable closures for such
openings, digesting tanks arranged in proximity to the openings in the tanks,
but on a lower plane to such openings, openings in the upper ends of 'said digest-
ing tanks, and means for communicating by ducts, hetween the tanks 11 and the
digesters, as set forth.
3-in an apparatus for handling, and for extracting the marketable products
from fish offal, the combination of a series of tanks, for first receiving the offal
and digesters to receive the same therefrom, said digesters being of cylindrical
form and having conoidal ends, perforated bottoms arranged sloping, just above
the depending cones of the lower ends, and closable openings above such bottoms,
for the ejectment of the refuse after being treated, as set forth.
4-In a digester for extracting the marketable products from fish and fish offal,
a closable vessel having conoidal ends, an opening in the upper end of same, a
foraminous bottom supported on an uneven plane just above the cone of the lower
end, and a closable door 24 on the lower plane of and above such bottom, and
ducts for injecting steam above and below the said bottom, as and for the purposes
set forth.
5 In a means for handling and a vessel for treating fish and offal, in com-
bination with the tank or tanks described, for the reception of the raw material,
means for closing said tanks, and for injecting steam to the interior thereof on top
of the matter to be treated and to beneath a foraminous supporting bottom in
the bottom of said tank or tanks, until all the gelatine is dissolved, and then means
for forcing the released liquids downwards through the perforated bottom, as set
forth.
6In an apparatus for the purpose described, the combination of receiving
tanks 11 for the offal, and means for transferring it from one or more of them
continuously to closed tanks 20, of means for applying a dissolving agency to
the offal, while in the closed vessels, and of finally ejecting the oily and aqueous
matters therefrom by steam pressure, as set forth.
300
1000
WILLIAM G. TRETHEWEY,
Agent, Vancouver, B.C.