Improvements in Apparatus for Digesting and Concentrating or Drying Organic Substances.
Year: 1899

page_text: Date of Application, 15th Nov., 1899-Accepted, 5th May, 1900
Improvements in Apparatus for Digesting and Concentrating or
Drying Organic Substances.
I, ALBERT TOTTE, of Kaiserstrasse 67, Magdeburg, in the German Empire,
Manufacturer, 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:-
This invention relates to apparatus for digesting and concentrating or drying
organic substances and consists in an improved construction or arrangement of
a continuously working combined digesting and drying apparatus for this
purpose. The improved apparatus is chiefly intended for the manufacture of
artificial manures, and applicable to other purposes. Although certain kinds of
artificial manures are manufactured from cheap organic substances, which
mostly are waste or residual products, such as leather or felt parings, bones,
wool waste and the like, the process for obtaining them is comparatively costly
so that these intrinsically valuable manures cannot be sold at a price allowing
small farmers to use them.
With the steamers or digesters hitherto used in which the substances are
digested and liquified in presence of a suitable acid, the process requires a com-
paratively long time and much steam, as the digester after the conversion of a
charge has been completed, must be emptied, refilled and reheated. On empty-
ing out the finished product or filling in a fresh charge the steam contained in
the digester escapes, so that on the next admission of fresh steam a large
quantity is condensed, and the water formed detrimentally dilutes the acid used
and is only gradually brought to the boiling point by the continuously entering
fresh steam and re-evaporated, so that only after this the, apparatus begins its
work. Thus a large consumption of steam and acid is one of the defects of the
hitherto known digesters.
When the substances have been digested and converted into a gelatinous
mass, this has further to be dried sufficiently to allow it to be broken up or
granulated in order to be ready for use. With the peculiar condition of this
gelatinous mass capacious artificially heated drying apparatus is required which
by their cost of construction and maintenance and large steam consumption
so as to make it
increase the price of the finally obtained artificial manure
The expensive heating by steam cannot be avoided until now, as the sub-
stances to be converted must not be heated to more than 120° C, if valuable
ingredients are not to escape and reduce the value of the product.
prohibitive in many cases.
The object of this invention is to remedy these defects by utilising both the
digesting and evaporating effect of the steam used completely. This is attained
by combining the digesting and drying or concentrating apparatus in such a
way that the same steam, that is used for concentrating or drying the converted
is further utilized for heating and digesting the materials and the final
mass,

page_text: product is delivered freed from water but in a hot liquid state, so that a con-
tinuous working is obtained and all losses of steam and heat are as far as
possible prevented.
On the drawings appended hereunto the improved apparatus is shewn by
Figure 1 in vertical section, Figure 2 in partial outside view and Figure 3 in
horizontal section.
Upon a conical base A, which may be the steam generator itself, or as shewn
on the drawings, have steam conducted to it through the pipe a pipe Bis
mounted, provided at its upper end with holes & into which pipe another pipe C
forming a tubular shaft is inserted. This pipe is provided with a worm, vanes,
blades or other, stirring appliances, in or near which preferably also steam outlets
are arranged.
The central steam pipes BC are surrounded by a jacketed cylinder DD¹
which in its lower part approaches closely to the conical heater A, and at the
height of the stirrers is likewise provided with steam outlets, so that at or near
to the stirrers crossing jets of steam flow into the space enclosed by the jacketed
cylinder DD', which receives the materials to be treated.
Steam may be admitted to the jacket at any place, for instance through the
pipe e connected to the pipe E which receives steam from the boiler, and
supplies both the conical heater and the jacket.
At the top the jacketed cylinder is closed by the charging funnel or hopper F
containing a bearing f for the tubular shaft U of the stirrers, which rotates in
a second bearing fand is provided with driving mechanism, for instance a
belt pulley G rotated by the belt g so that the stirrers revolve inside the
jacketed cylinder D'. In order further to increase the heating surface, prefer-
ably heating tubes H are arranged on the inside wall of the cylinder, which tubes
may be carried down outside the conical heater A, or only reach to the top
of the same as shewn on the drawing. In the latter the case the cone is
preferably formed with heating ribs as indicated in Figure 2.
The lower part of the annular jacket does not extend to the bottom of the
heater A. The inner wall D₁ is extended farther than the outer one and
attached tightly to the heater A and is provided with openings through which
the substances transformed into a thick liquid can issue in the form of hot
liquid bands or the like.
In consequence of the height of the apparatus a column of materials is formed
in it the pressure of which suffices to effect the outflow of the thick fluid produced,
freed from the greatest part of water.
The apparatus is worked in the following manner: The materials to be
converted into artificial manure are charged into the apparatus through the
funnel F and fill it above the stirrers, while at the same time steam is admitted
into the heater A, the annular jacket DD! and the heating tubes H and enters
into the materials through the outlet holes bh, at the same time as the materials
are continuously sprinkled from above with a suitably diluted acid through
the pipe I. As stagnant steam heats badly, and it is necessary to use flowing
steam if a quick continuous working is to be obtained, the tubes H are open
at the top, and the internal wall D of the jacket is likewise provided with
outlet holes at its upper end, so that at this point the steam, which has already
done most of its work, issues in crossing jets and entering the materials in the
funnel F mixes with the acid and thus produces a preliminary warming and
steaming of the materials, which is assisted by the steam rising from below.
When the materials surrounding the stirrers have become digested so as to
become liquid and form a pasty mass, the stirrers are started to revolve, the
pasty mass descends through them and the funnel F is refilled as it gets
emptied. Gradually the whole space below the stirrers is filled with the mass,
which is heated in its entire column from the outside and inside, so that the
water contained in it is evaporated more and more.
then filled just below the funnel F with warmed and softened material, just
The jacketed cylinder is

page_text: above the stirrers with a gelatinous mass, which below the stirrers is of com-
paratively thin fluid consistency and gradually becomes thicker or denser lower
down. Flowing down the conical heater A it is deprived of the rest of its
water, and issues from the openings o in a consistency similar to water free
melted glue, and getting cooled by the air becomes rigid, so that it can easily
be broken into pieces or converted into powder.
When the apparatus is once at work, raw materials have to be filled in con
tinuously, as the finished product flows continuously out of the openings at the
bottom, and notwithstanding its simplicity the output of the apparatus is very
large and not even approximately attained by any apparatus of the same capacity
hitherto known, with all of which the digested material has to be further dried
on special drying apparatus and freed from its excess of water. This continuous
working naturally affords a great advantage over the usual periodically charged
But this is
and emptied apparatus, as the productivity is greatly increased.
not the principal advantage which is found in the complete utilisation of the
steam and acid. For the continuous working makes it possible to charge the
raw materials in small quantities and thereby to avoid the formation of larger
quantities of condensed water, which cause an irreparable loss through the
liberation of heat on condensation. The quantity of steam issuing from the
upper part of the steam jacket and the heating tubes H is comparatively small
and when the dimensions are correctly proportioned, not larger than can be
absorbed at once by the raw materials, whereby they are warmed and softened,
so that the steam ascending from the mass below do not suffer any noticeable
condensation but only continues to heat and digest and escapes as exhaust steam
of a minimum heating value.
The abduction of this exhaust steam or vapour naturally cannot be avoided
as this has to be done in every drying process. This consequently is no less
compared with other apparatus, but such only occurs where the steam under
pressure, as required for the conversion of the raw materials, escapes. The acid
also is utilised in the most efficient manner, as it undergoes no noticeable dilution
and subsequent re-concentration, but in the improved apparatus acts from the
beginning in the correctly concentrated slate, so that the conversion of the raw
material for this reason takes place much quicker than with the usual apparatus.
The whole apparatus is further surrounded by a shaft of masonry enclosing
an insulating air space round the steam jacket D D' and preventing the cooling
of the outer wall of the jacket. It may also be used as a drying space or for
similar purposes if desired.
The removal of solid lumps if any, from the space between the jacket and
the heater A can be effected through the outlet pipe's closed by a cover or
through a suitable manhole, and for this purpose it is advantageous to form the
lower end of the drying space inclined, so that such lumps when the outlet
pipe is opened are carried down by the current of the liquid mass and removed.
Obviously the apparatus where suitable may be used for digesting and con-
centrating or drying other materials than those mentioned at the beginning of
this specification, or for digesting and concentrating or drying organic substances
for other purposes.
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. The construction and use of an apparatus for digesting and concentrating
or drying organic substances for the manufacture of artificial manure or other
purposes substantially as herein before described and illustrated by the drawings.
2. In apparatus for digesting and concentrating or drying organic substances
the arrangement of a vertical steam jacketed cylinder and an internal steam
pipe or more than one having outlet holes into the cylinder or about the level
of a stirring apparatus arranged inside said cylinder, so as to form a digester

page_text: in the upper part and a concentrator or dryer in the lower part, substantially
as hereinbefore described and illustrated by the drawings.
3. In apparatus for digesting and concentrating or drying organic substances
having a steam jacketed vertical cylinder and central steam pipe, the arrange-
ment of a large conical steam heater communicating with said pipe and a corre-
sponding conical lower part to said jacketed cylinder with a narrow space
between the heater and conical jacket and outlet openings at the bottom thereof,
for the purpose of depriving the thick liquid contained in the lower part of
the cylinder of the remnant of its water, substantially as herein before described
and illustrated by the drawings.
4. In apparatus for digesting and concentrating or drying organic substances
having a steam jacketed cylinder and internal heating pipes with outlet orifices
at the level of a stirrer arranged inside said cylinder, arranging a charging
hopper at the top and openings at the bottom of said cylinder and making the
latter of such height that the weight of the materials contained therein can
force the heated fluid mass out of said openings, for the purpose of obtaining
a continuous action of the apparatus, substantially as herein before described
and illustrated by the drawings.
.
•
1000
R. J. URQUHART, C.E.,
Chartered Patent Agent, Manchester and Liverpool.