Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~25~3
'METHOD OF AN APPARATUS FOR DEGRADING OF ORGANIC PRODUCTS
BY-PRODUCTS AND SCRAPS IN AN ANAEROBIC MEDIUM"
The present invention relates to a loathed end an
apparatus or lunate for carrying out the degradation of
organic products, by-products an scrips or waste from
human, animal and/or vegetable origin.
ore specifically the sub~eGt tatter of tune invention
is a process and a device for performing a continuous
~et`rianizing of solid and/or liquid organic compounds.
Organic materials prom various such a human, animal
or vegetable origin may lead through successive or simulate-
10 awns microbiological degradations in an anaerobic medium to gaseous compounds the most important of which are
methane and carbon dioxide.
The nature and composition of these organic products
are very variable and they consist ox more or less polyp
merited and imbricate elements. These organic products
would mostly form a solid substrate whether fibrous or not
with a high content ox dry matter. This is in particular
the case of town and agricultural refuse 9 garbage or
litter or instance. Such products may however also be
20 liquid with small contents ox dry matter such or instance
as the sludges from purification plants or stations,
liquid manures, milk serum.
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The major part of such substrates consists of ternary
compounds such as sugars, starches, hemicelluloses 9
cellulose and lignins but quartenary substances such as
provides and peptizes may also be associated therewith,
The agents participating in such degradations are
generally coming from animal, plant and -tell uric habitats.
Numerous species or kinds have been found out. They are
evolving within mediums with very variable pi and reduce-
ion-oxidation potential with ranges differing with the
psychrophilous misfiles or ther~ophilous kinds
In a simplified manner the degradation of an organic
matter and in particular of an insoluble organic matter in
an anaerobic medium would proceed according to three steps:
- a hydrolysis step during which the enzymes would
convert the insoluble compounds into soluble substances;
- an acidogenous step during which dissolved organic
matters are converted into compounds such as fatty acid
alcohol or others. wring that acidogenous step there is
an acetogenous step during which is generated acetic acid
which is one ox the cGmpo~d~ which are essential for the
formation ox methane during the following last step:
- a methanogenous step during which methane hod
carbon dioxide are produced.
Fermentation processes are already known which
consist in using digestion tanks, vats or like vessels
operating continuously or discontinuously (botch product-
ion). The batch-wise or discontinuously operating tanks
are used especially with organic products or solid and
heterogeneous substrates and are neither convenient nor
industrially profitable. True continuously operating
digestion tanks are almost essentially used with liquid
effluents with a small content of dry matter. In such
devices indeed the treatment of a solid substrate whether
heterogeneous or not involves many di~ficulties,in
particular in correction with the circulation and home-
genization ox the substrate within the tank thereby
- resulting in bad operating conditions and strongly disturb-
in or interfering with the process of degradation ox
I
organic matter The efficiencies or yields ox such plants
are relatively low. To provide for a mechanizing under
suitable conditions, it was therefore necessary to use a
liquid substrate or a substrate greatly diluted through
addition of water This amount of water associated with
the substrate to be processed would result in the occur-
fence of polluting liquid refuse and the use of bulky tanks.
From the French patent specification publication No
2,3~5~113 is for instance known an apparatus for the
10 digestion ox organic matters wherein the material to be
processed after having been damped or moistened is fed into
a cylindrical compartment wherein it undergoes an aerobic
fermentation under pressure and is then driven or pushed
by a ramming piston through a bent siphon into a small
anaerobic fermentation compartment and thereafter into a
large compartment. Within the bend or elbow of the siphon
forks would prevent the material from flowing back.
According to said patent specification, there is also
provided an extraction shaft or well wherein -the fe~nen-
20 ted matter is curried along by a claw.
I The object of the present invention is to remove such
difficulties by providing a method of and an apparatus for
performing the aerobic fermentation of organic products,
by-products or waste or refuse of hygiene, animal or plant
origin in particular with a high content of dry matters
whether heterogeneous or not while effecting a good
homogenization of the products within the digestion tax
to thereby promote on the one hand the process of
degradation of the organic material and on the other hand
the circulation of the products within, the tank through
an effect of fluidization of the mass of products.
or that purpose, the invention provides a method of
carrying out a degradation in an anaerobic medium or
instance a methanogenesis of organic products, by-products
or waste from human 7 animal and/or vegetable origin
consisting in feeding said products to be degraded into a
closed vessel after having possibly sowed or seeded said
products with a suitable substrate, forcing said products
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to follow a direction of circulation within said vessel,
recovering or collecting the gas called buggies evolved
above said mass of products and discharging the degraded
products 3 said method being characterized by the step of
carrying out the feeding and discharge of the products to
be degraded pneumatically for instance through a pneumatic
thrust. This pneumatic thrust can be caused through
injection of gas, preferably buggies.
With such a pneumatic feeding and discharge of the
products the processing is unexpectedly improved notably by
the fact that the problems of blocking or clogging and
corrosion in connection with mechanical devices for
supplying or extracting the substrate are removed. Also J
the construction of the apparatus is simplified and it is
further possible to treat products or substrates having a
very high content in Wry matters whether heterogeneous or
not.
According to one embodiment of the invention method,
said method comprises causing the pressure of buggies
20 contained within said closed vessel to suddenly and sharply
drop intermittently thereby inducing a flux and reflex or
back and forth motion of the mass of products Tithing said
vessel.
According to another characterizing feature of the
; invention method! it is performed an injection ox produced
buggies into the mass of products contained within said
vessel, preferably through emission of short jets or
blasts by intermittence under pressure
According to a preferred embodiment of the invention
30 method, said method further comprises sub-dividing said
closed vessel into a plurality ox sections; and injecting
intermittently buggies, preferably produced biogas,into
each one of said sections under a pressure and during a
period of time predetermined, set in relation to the
density of the products within the involved section.
Accordingly, according to the invention method, the pressure
of the injection ox buggies and the duration of injection is
adapted in relation to the actual density of the solid
products or of the substrate in the injected section It
.,
I
can therefore be easily understood that it is obtained
with the invention an essentially perfect fluidization of
the products during their slow throughout the fermentation
vessel.
Further, according to a still preferred embodiment
of the invention process, buggies is introduced into each
section successively, i.e. displaced or shifted in the
time, so as to obtain in practice a rotation of the buggies
injection within the vessel, from a section to another one.
10 This rotation ox buggies injection can be regular or
irregular, i.e. said injection can begin prom a given
section and be followed by injection in another section
not adjacent to the just previously injected section, said
first injected section, being selected in view of its
actual density and fluidization effect to be reached.
Also, according to the invention method, the buggies
injection can be prewarmed. Such a programmation
can be performed with the aid of any Milwaukee known to one
skilled in the art and in particular through use of a
20 microprocessor or a computer
The invention is also directed to an apparatus or
plant for carrying out the method described hereinabove
and which is of the kind comprising a reactor or digester
with an anaerobic fermentation vessel, tar or provided
with substrate feeding means and substrate discharging
means, respectively, a gas or buggies outlet connected to a
gasometer or like gas holding vessel, wherein the improve-
mint is characterized in that the fermentation vessel
comprises a partition wall dividing said vessel into 2
first part and a second part, said partition wall having
a height smaller than that of the vessel, said first part
being collected to said substrate weeding means and said
second part being connected to said substrate discharging
means, at least one of said substrate feeding means and
said substrate discharging means comprising means for
introducing gas under pressure so as to yield a
pneumatic thrust of the products to be degraded into said
vessel. This gas is preferably buggies.
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According to a particular embodiment of the invention
apparatus, each of said substrate eddying means and
substrate discharging means comprises a substantially
vertical shaft which can be closed and at the top of which
is connected said buggies introduction means so as to
yield said pneumatic thrust in said shaft.
According to another characterizing feature of the
invention apparatus, said buggies outlet is connected to
said gasometer through a gate or valve and in particular
I a hydraulic valve.
According to a still further characterizing feature
of the invention apparatus, said fermentation vessel is
provided with a plurality of buggies injection ducts,
laterally spaced one with respect to the other and located
at least in the major portion of said vessel, said buggies
injection ducts being fed individually or by groups with
buggies through independent gates or valves, thereby sub-
dividing the fermentation vessel in-to buggies independently
fed sections.
According to an advantageous embodiment of the
inanition apparatus, the Boyce injection circuitry
comprises a buggies storage container in which buggies is
gathered and stored until o~tention of 2 pressure at
least equal to the highest prosier required in one of
said vessel sections
according to the invention, each gate or valve is
foreseen and designed so as to provide a pressure in
relation to the density of the products within the
associated or related section.
according to a preferred embodiment of the invention,
said apparatus further comprises programed control
device for each gate or valve of Mach section.
According to a still further preferred embodiment of
the invention apparatus, said apparatus urethra comprises
a buggies injection conduit at the top of the fermentation
vessel provided with an appropriate gate or valve,
thereby allowing possibility of performing a pneumatic
thrust in the fermentation vessel which is preferably
SLY
performed simultaneously to the extraction or discharge of
the fermented products from the fermentation vessel or
instance in direction to the substrate discharging means.
Furthermore, said partition wall splitting the
fermentation vessel into a first and a second part is
preferably formed with a passageway for communication
between said first and second parts at least at the bottom
of the vessel.
According to still another characterizing feature of
10 the invention, the apparatus comprises a compressor the
inlet of which is at least connected to said gasometer and
the outlet of which is connected notably to said plurality
of ducts or pipelines opening into the bottom of the
vessel, said ducts being advantageously fitted with a
check or non-retuln valve or gate. These ducts or pipe-
lines opening into the bottom of the vessel may possibly
be provided with 2 valve for blowing buggies in successive
short jets.
Moreover, said compressor outlet is also preferably
20 corrected to ducts or pipelines opening into the bottom
of slid feeding arc discharge shafts and/or to ducts open-
in at the tops of said feed and discharge shafts each
duct being fitted with at least one shutoff valve. It is
-thus possible to recycle the Boyce to all the part of
the apparatus.
In addition, the apparatus can also comprise an air
compressor, the outlet of which is collected to said feed
shaft and/or discharge shaft for thereby inducing or
continuing if desired a degradation in an anaerobic medium
30 within the feed shaft and accelerating the process of
convention of the substrate within the discharge shaft
with a vie to being used as compost.
The apparatus also comprises means for recycling
into said reactor and/or into the feed shalt or the
discharge shaft the liquid separated from the fermented
solid products recovered at the outlet of said discharge
shaft this liquid being a leaven or an inoculum.
According to still another feature of the invention,
the feed shaft is provided with two series of slots or
,
slits spaced by some distance from each other and located
at some distance from the cover or lid and the bottom end
of the shaft, respectively.
Moreover, said valve controlling the discharge of
buggies produced within the vessel can be located either
outside of the Al or within the shaft whereas the
gasometer is either outside of the TV or above the latter
In the latter case, the gas would escape through a pipe
which extends through the vessel and leads to a condensing
siphon adapted to collect or gather the water present
within the buggies originating from the fermentation.
Preferably these gases are then carried to a purifier
like scrubber, cleaner or filter.
Furthermore, according to a first embodiment of the
fermentation vessel or reactor of the invention, said
feed and discharge shafts are located near each other,
said partition wall being arranged vertically between both
end openings I said shafts leading into the vessel and
such partition wall having 2 width smaller than the wit
of said vowel and a height smaller than the height of -the
v~s~l,whereas the bottom of the latter exhibits a double
slope and is advantageously of elliptic shape.
according to another embodiment of the fermentation
vessel of the apparatus, said fee and discharge shafts
are arrange in substantially diametrally opposed
relationship on the periphery of said fermerltation vessel,
said partition wall being arranged vertically and directed
substantially along a diameter of the vessel and having 2
height smaller than that ox the vessel. The bottom of
this vessel preferably has a single slope or pitch
whereas said partition wall is formed with a passageway
at its lower portion
Lastly, the apparatus comprises heat exchangers for
corralling out various heat exchanges between the fluids
flowing within the apparatus and in particular for
heating up the leaven or inoculum before its being fed
into the fermentation vessel or reactor or digester.
The invention will be fully and completely understood
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and further characterizing features, details and
advantages thereof will appear clearly as the following
explanatory description proceeds, with reference to the
accompanying diagrammatic drawings given by way of non-
limiting examples only, illustrating various embodiments
of the invention and wherein-
Figure 1 is a vertical section through an embodiment of the apparatus according to the invention;
- Figure 2 is a view in cross-section taken upon the
line II-II of Figure 1;
- Figure 3 is a view in vertical section showing
another embodiment of the apparatus according to the
invention;
- Figure 4 is a vie in cross-section taken upon the
line IV-IV of Figure 3;
- Figure 5 is a view in vertical section of another
embodiment of the apparatlls according to the invention,
with parts broken away;
- Figure 6 is a vie in cross-section -taken upon the
line VI-VI of figure 5;
- Figures arid 8 are conspectus or bloc; diagrams of
the apparatus of the invention with all the buggies
circuitry;
- Figure 9 is a conspectus or block diagram of
another embodiment of the invention apparatus and buggies
circuitry;
- Figures aye 10b, aye, 11b are schematic views of
the fermentation vessel of the invention apparatus to show
the results of the method according to the invention on
the state of the substrate within the fermentation vessel;
- Figure I is a schematic view showing an apparatus
for treating the fermented substrate at the output of the
fermentation vessel; and
- Figure 13 shows a modification of the invention
apparatus subject matter of Figures 5 and 6 and is a view
in cross-section of the bottom of the fermentation Bessel,
seen from the top thereof and shows all the buggies
circuitry for introduction of buggies in the bottom of the
3. I
fermentation vessel,
Referring to Figures 1 and 2, a first embodiment of
the invention apparatus or plant and in particular a first
embodiment of the fermentation vessel or reactor thereof
will be described
The fermentation portion or reactor 1 of the invention
apparatus comprises a substrate feeding or supply means 3
here constituted by a substantially vertical shaft, closable
in fully sealing or ~luid-tight relationship by a cover or
10 lid pa, a fermentation vessel 2 with a dome-shaped cover pa
and a substrate discharging means 4, here constituted by a
substantially vertical shaft, closable by a cover or lid aye
The fermentation vessel 2 is separated by a partition wall
7 into a first part and a second art The first part is
corrected to feeding means 3 and the second part is
connected to discharge means 4. The partition wall 7 is
here shown positioned substantially along a diameter of
the vessel 2 and having a height smaller thin that of the
vessel 2. moreover, -this partition wall 7 preferably
20 leaves a passageway I at ifs lower portion, i.e. in the
vicinity of thy bottom of thy vessel 2.
In the embodiment shown on Figure 1 and as clearly
seen on Figure I, the feed and discharge shafts 3 and 4
are arranged in dipteral opposite relationship on the
periphery of the vessel 2 and are connected to the first
and second parts, respectively, ox the vessel 2 through
siphons 5, I The siphon 5 may possibly be fitted with a
means such as chain 35 flexible in one direction only
and breaking or preventing any ~ackflow or return of the
substrate during the anaerobic fermentation towards the
feed shaft 30
The vessel 2 comprises a gas outlet duct or pipeline
pitted with a shut-off valve boa and opening in the shown
embodiment into a hydraulic valve 11, the gas or buggies
then evolving through the duct or pipeline 12 to flow to a
gasometer 15 not shown on Figure 1.
The feed shalt also comprises two series of slots or
slits 8 spaced from each other on the feed shaft 3 and
5:~73
7 1
circu~ferentially located thereon
The vessel 2 can also comprise chains 9 suspended
from the dome-like portion pa of the vessel I the function
of which will be described later.
In the embodiment shown on Figure 1, the discharge
shaft 4 is provided at its top with a cover pa pitted with
a gas duct or pipeline 115, an outlet siphon 127 and on
outfall or like overflow chute or spool 128 with an
adjustable opening or outlet port 129
furthermore, the apparatus 1 comprises several ducts
either or draining away the gases from the discharge or
feed shaft or for feeding air into this discharge or
feed shaft or for feeding leaven or inoculum into the
vest 2. These various ducts will be described more in
detail together with the description of the ducts of the
apparatus
The second embodiment of the apparatus 1 according to
the invention, shown on Figures 3 and 4 differs prom the
first embodiment if, that -the hydraulic valve 11' is
20 arranged within the reactor vessel 2, the latter being
topped by a ~asomcter 15'. True valve 11' is fitted on a
duct 10' one end ox which extends as the pipe I on Figure
1 from the top pa of the vessel rowers its other end
opens into the gasometer 15'~ Into the latter opens a
pipe 145 which leads on the one hand lo h condensing
siphon 146 adapted to collect or recover the water present
within the hot gases or biogases evolving from the
fermentation and which is condensing within the pipe 145
and on the other hand to a duct for conveying the buggies
30 roadside for instance into a purifier, clearer, scrubber
or like filter eons 2 shut-off valve 147 being provided
on the duct 1450
In Roth ox the embodiments described, the fermentation
vessel bottom 2b has one single slope or pitch and the
inlet siphon 5 is located at a higher level than that ox
the siphon 6.
The embodiment of the invention apparatus shown on
Figures 5 and 6 differs from both previous embodiments in
that the shafts 3 and 4 are arranged near each other on
5~'73
12
the periphery of the Bessel I The partition wall 7 is
then located between the inlets of both siphons, 6
within the fermentation vessel 2, its width being smaller
than the width ox the vessel so that the substrate may
flow in the direction of the arrow F. Moreover, as in
both embodiments, the height of the partition wall 7 is
smaller than that of the vessel I In this embodiment,
the siphon 5 associated with the feed shaft 3 is also
positioned at a higher level than that of the siphon 6
associated with the discharge shaft 4. The bottom 2b of
the fermentation vessel 2 exhibits a double slope or pitch
and is advantageously of elliptic shape.
Furthermore, the chains 9 fastened to the dome-shaped
top pa of the vessel 2 advantageously carry weighty or
heavy elements pa such as metal discs, these discs being
fastened to the chains 9 preferably at the lower portions
thereof. Thus the chains 9 are suspended from the dome-
shaped top pa of -the vessel so as to hug freely down into
the vessel or being embedded at least partially into the
substrate to be processed as clearly shown on Figures aye,
10b, aye, 11b. It is of course possible to arrange these
chains 9 together with the weighty or heavy elements pa
within the vessel shown on Figures 1 to 4.
moreover, according to another alternative embodiment
of the invention, the outlet siphon 127, the outfall or
like overflow-shoot or spool 'i28 provided on the
discharge shaft 4 may be substituted for by a drain or
egress duct fitted with a shutoff valve (not shown).
Referring to figures 7 to 9, the apparatus according
to the invention and in particular the various fluid-
carrying ducts thereof will now be described.
For the sake of a better understanding of these
drawings those ducts wherein the buggies is flowing are
shown in heavy solid lines whereas those ducts which
carry the levee or inoculum are shown in thin solid
lines and those ducts wherein air is flowing are shown in
broken or dotted lines
In the whole apparatus or plant as shown on Figure 9,
,
I,
i2~5~ 73
the fermentation vessel 2 is connected to the hydraulic
valve 11 through a gas outlet duct 10 fitted advantageously
with a shutoff valve aye. The hydraulic valve 11 is in
turn corrected to the gas holding vessel or gasometer 15
through a duct or pipeline 12 in which are mounted for
instance a gasometer 14 and a container 13 forming a
buffer gasometer
It must be noted that a gate or valve actuated for
instance pneumatically, electrically, hydraulically,
10 electromechanical and so on be substituted for the
hydraulic valve 11 or the same purpose,
The gasometer 15 is fitted with an outlet duct 16
provided with a shut off valve aye and which is connected
on the one old to a duct 17 for carrying the gas for
instance to a purifier, a storage station or a burner, and,
on -the other hand, to the inlet of a was compressor or
booster 18 to provide for the circulation of the buggies
within the whole apparatus or plant. The outlet 19 of
this gas compressor or booster 18 is collected -through a
20 duct 21 and branch ducts 22 and 23 through valves aye
to the top portions of the feed and discharge shafts 3,4,
respectively with the purpose of providing the pneumatic
thrust of the substrate as previously emphasized.
The outlet I ox the booster I is also connected
through a duct 20 fitted with a valve aye to the bottom
portions ox the feed and discharge shafts 3,4 through the
ducts 24,25; and to -the bottom portion of the vessel 2
through a plurality of ducts 26, with, in the latter
case, the purpose of injecting buggies at the bottom of the
fermentation vessel 2. A preferred embodiment of said ducts
will be described with reference to Figure 13.
On the other hand, the top portion of the fermentation
vessel 2 is connected to the inlet of the compressor 18
through a duct 27 fitted with a valve aye.
According to a preferred alternative of this embody-
mint, the top portion ox the fermentation vessel 2 can be
connected to the outlet ox the compressor 18 through a
derivation duct I to duct 23 fitted with an associated
7~3
I
valve aye with the purpose of performing a pneumatic
thrust within the orientation vessel 2 through injection
of buggies through valve aye at the top of the fermentation
vessel 2 simultaneously to the cutting of of the pneumatic
thrust within discharge shaft 4.
Preferably, the ducts 26 opening into the bottom of
the fermentation vessel 2 and the ducts 24 7 25 are fitted
with check or non-return valves (not shown for preventing
materials contained within the vessel from falling into
said ducts. Moreover, the ducts 26 may possibly be
provided with valve means (not shown) adapted to emit
short and successive jets under pressure.
The gas circuit shown on Figure 9 described herein-
below is riven by way of illustrative example only It is
of course possible to provide other ducts or devices
valves, gates or the like for carrying out any possible
circuits for the flow of gas within the vessel and for
instance to provide heat exchanges with other fluids
within the apparatus or plant as shown on Figures 7 and 8.
In these Figures, the circuit for recycling the
buggies within the apparatus is not shown.
One inaction of the buggies recovered within the gas-
meter 15 is directly fed into the purifier 111 whereas
another fraction is put in heat exchanging relationship
with the air possibly supplied into the feed shaft 3,
within the heat exchanger 110 and then through the ducts
108,113 and valves 109,~12, it also undergoes a heat
exchange within the heat exchanger 114 with the levee
recycled into the apparatus 1. This buggies fraction is
then fed into the purifier ~11 through the pipeline 115.
Advantageously the buggies present at the upper portions
of the feed and discharge shafts is fed into the purifier
111 .
The flow circuits of the leaven or inoculum and of
the air will be described at the same time as the
operation of the plant.
Finally, with reference to Figure 13, the best mode
of the invention apparatus comprises fermentation vessel 2
~5~3
of the type shown in Figures 5 and 6 but modified as
follows with respect to introduction of buggies into the
fermentation Bessel 2 and fed from the gasometer of the
type for instance of a gasometer 15 of Figure 9.
Duct 16 receiving buggies at the outlet of gasometer 15
is shown at the right of Figure 13~ The compressor 18 is
provided on this duct 16 as shown in Figure 9 and the duct
19 connected with the outlet of the compressor 18 is sub-
divided into ducts 20 and 21 exactly as in the case of
Figure 9.
However, according to the present modified embodiment,
duct 20 does not deliver the buggies immediately to the
bottom of the fermentation vessel 2 but is connected to a
buggies storage container 300 able to support a high
pressure and in which buggies is gathered and stored until
obtention of a predetermined high pressure which will be
defined later,
A duct 302 is collected to the outlet of said buggies
storage reservoir 300, said duct 302 being sub-divided
into a plurality of sub-ducts 304,306,30~,310,312,314,316,
318, each being provided with an individual Nate or valve,
respectively 320-322-324-326-32~-330-332-334.
The sub-ducts 304 to 318 are feeding buggies to a
plurality of buggies injection ducts 340,342,344,346~348,
350,352,354,356,358,360,362, ~64,366,368,370 which are
located in the location of the bottom of fermentation
vessel 2 and which are constituted by hollow tubes of
appropriate section longitudinally provided with a
plurality ox injection openings such as 37Z.
According to the present invention, said plurality ox
buggies injection ducts 340 to 370 is fed with buggies India-
ideally or in groups J for instance two by two as shown on
Figure 13, via the independent valves 320 to 3}4 so as to
sub-divide the fermentation Bessel 2 in sections in depend-
entry fed with buggies The limits of the sections have
been symbolically materialized on Figure 13 by the presence
of the dotted lines 374,376,378,380,382,384,3~6. In the
embodiment shown on Figure 13, it thus appears that eight
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16
sections have been defined. It will be noted that the
buggies injection ducts are laterally spaced between -them
and located at least in the major portion ox the ferment
station vessel 2$ preferably regularly as shown Further
the specific construction of the buggies injection ducts
~40 to 370 is a part of the invention
Further, according to the present invention, each
valve 320 to 334 is foreseen designed or constructed so as
to provide a pressure in relation to the density of the
10 products in the associated section. besides each valve is
controlled preferably according to the invention through a
programmed control device (not shown), so as to inject
intermittently buggies into each of the sections of the
fermentation Bessel 2 under pressure and during a period of
time predetermined, set in relation to the density of the
products in the associated section.
By the terms "pressure of injection in relation to
the looniest ox the products in & given section'' - it is
intended to emphasize that the injection pressure is
sufficient to yield a ~luidiza~ion of the mass of the
products or substrate to be fermented or in fermentation
having the said density.
It will thus be understood that the injection pressure
is actually commensurate or adapted to the actual density
of the mass of products or substrate in the section where
is injected buggies.
Thus, with the invention apparatus, the previously
set forth method is performed, namely the obtention of a
sub-dividing of the fermentation vessel 2, into a plurality
of sections. Further, with a view of performing a
substantially perfect or homogeneous fluidization of the
solid products or substrate within the fermentation vessel
2, the invention method comprises injecting intermittently
buggies into each one of the sections under pressure and
during a period of time predetermined, set in function of
the density of the products within the associated section.
Further, according to a further characterizing
feature of the invention method, buggies is injected into
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17
each section successively while being shifted in the time
so as to obtain a so-called buggies injection rotation
within the fermentation vessel 2 prom a section to the
other. This injection can be regular or irregular and
therefore a given section can be injected with buggies
whereas one or several of the adjacent sections are not
injected with buggies should in said sections the fluid-
ization of the products be satisfactory, ire. the
density of the products. Besides, and with the aid of the
JO programmed control device, it can be obtained a programmed
injection. This progra~mation can be automatically servo-
controlled by means detecting a lack of fluidity within
one of the sections of the fermentation vessel 2 so as to
immediately order an injection in the concerned section by
acting on the corresponding valve.
It should also be noted that according to the
present invention, the presence of the buggies storage
reservoir 300 provides unexpectedly for Gone skilled in the
art the use of a compressor 18 of low capacity, namely
with a low compression ratio.
Further, with the presence of duct 23', Figure o'er
injection of buggies at the top of the fermentation vessel
2, it can be performed a pneumatic thrust from the top of
the fermentation vessel 2 so as to easier discharge the
solid products flowing on the bottom of the fermentation
vessel 2 towards the discharge shaft 4. Preferably,
according to a further characterizing feature of the
invention method, the pneumatic thrust in the fermentation
vessel 2 is performed simultaneously with the pneumatic
thrust in the discharge shaft 4. Further, according to
the invention method, the previously said pneumatic thrust
in the substrate feeding shaft 4 is performed simultaneously
to the setting to opening of buggies evacuating valve such
as valve boa of Figures 1 to 9, thereby improving the
forced feeding of the products or substrate to be fermented
It is therefore clear for one skilled in the art that
according to the invention, it is obtained a practically
perfect fluidization of the products or substrate even
1~3
with a high content in solid materials such as human waste
products and litter together with a simplified technology
of the m~lufacture of the fermentation vessel, in particular
with the sub-dividing I the fermentation vessel into a
plurality of independent sections as in the case of the
embodiment of Figure 13 by lowering the slope of the
bottom of the fermentation vessel, thereby yielding a
lowering of the Bessel costs.
Further, it is of course also obtained according to
10 the invention, unexpectedly an improved yield in buggies
The working of the invention apparatus will now be
described.
Organic products, by-products or waste from human,
animal or vegetable origin are possibly subjected to a
mechanical, physical, chemical or microbiological prelim-
nary treatment, for instance to a heat processing, a
pounding, crushing or milling or a chopping through a
chopper-projector, a quick depressuriz~tion or pressure
drop, an anorak pre-fermentation to for instance
20 promote the hydrolysis of the matter, the defiberization,
shredding or delignification in particular in the case
of cellulosic and ligno-cellulosic compounds. After the
opening of the cover pa the materials are then supplied
into the feed shaft 3. The cover is then closed again in
sealing or f-uid-tight relationship. Thereafter a gas is
supplied into the top portion of the feed shalt to build
up a gas pressure, for instance through injection of
compressed air produced by the compressor 28 and conveyed
through the pipeline 29 to the Lowry portion of the feed
shaft 3 or by feeding buggies through the pipeline 23 upon
opening the shut-off valve aye. The gas pressure prevail-
in at the bottom portion of the feed shaft 3 would drive
or push the products or substrates through the siphon 5
for feeding same into the first portion of the ~ermentat-
ion vessel I
The injection of air into the feed shaft 3 is carried
out it it is desirable to oxygenate the substrate supplied
or to induce, proceed with or continue a thermogenous
~25~73
19
aerobic fermentation of the substrate in accordance with
the nature of the substrate to be treated.
The substrate is thus fed into the first portion of
the fermentation vessel 2 and through an upward potion
would be poured into the second portion ox the ~ermentat-
ion vessel 2 through overflow over the partition wall 7
and then aster a downward motion would pass through the
siphon 6 to rise within the discharge shaft 4 where one
part will be periodically discharged by the siphon or
spout 127 through opening of the cover pa. It is also
advantageous to inject the air into -the discharge shaft 4
through the pipeline 36 or accelerating the process of
conversion of the fermented substrate with a view of using
same as a compost
As known per so and advantageously the substrate
recovered at the outlet ox the discharge shaft 4 is fed
through a spill-way or overflow shoot 130 into a press 138
which would separate the fermented solid part from -the
liquid or leaven and which may possibly be subjected to an
injection of air. A conveyor belt 139 removes the solid
matter whereas -the liquid is recovered or collected in a
vat 30, This leaven or inoculum thus recovered may be used
in various manners and may be recycled under the action of
a pump 31 to the various portions of the reactor 1 aster
having possibly been reheated in the heat exchanger 114.
It may thus be :
- recycled into the upper portion of the weed shaft
3 through the duct 32, in particular it a preliminary
thermo~enous aerobic treatment is carried out in the weed
shaft I or
- injected into the bottom portion of the ferment at-
ion vessel 2 through the ducts 33 or
- conveyed into the bottom portion of the discharge
shaft 4 through the duct 34,
These various ducts are advantageously provided with
valves aye, aye and aye, respectively,
The nature of the substrate processed within such a
plant may be very variable,
~5:~73
Moreover the plant and the process according to the
invention make it possible to conduct an anaerobic
fermentation of organic products and in particular a
methanogenesis with a substrate having a small content of
dry matters or with a substrate having a high content of
dry matter, of about 30~ for instance or more and whether
very heterogeneous or not.
Referring to Figure boa indeed without any stirring
and homogenization of the substrate in the reactor, a first
layer A loaded with gas and a lower liquid layer B will be
obtained very quickly, heavy materials C having been
separated or allowed to settle onto the bottom of the
reactor Within the layer A will then be built up a crust
or cover which would obstruct or clog the reactor thereby
preventing any circulation of the substrate and thus
blocking or discontinuing the continuous operation of the
digester and causing the fermentation to stop
According to the invention, to promote the anaerobic
degradation process within the reactor a homogenization and
a fluidization of the substrate are carried out by using
the buggies produced. Such a homogenization and fluidizat-
ion are in the embodiment of the invention carried out
through the combination steal effects connected with the
no cycling ox the buggies within the substrate, with the
flux and reflex motion of the substrate between the
fel~entation tank and the weed shaft 3 and/or discharge
shaft 4 and at last with the movements of the chains 9
and discs pa which latter can be absent.
On Figure job has teen diagrammatically illustrated
the state of the substrate when a recirculation or
bubbling of the buggies within said substrate is merely
performed This injection of buggies into the substrate
is carried out by means ox a compressor I either through
the ducts 22, 23 or through the ducts 24, 25 or through
the ducts 26 or through one or several of these ducts by
the opening or closing of the valves aye, aye, aye, aye,
aye
Such a recirculation of buggies however if it is
I 73
21
carried out alone is especially effective for the treat-
mint of a substrate with a small content of dry matters
providing for a scattering of the heavy products C and a
better distribution of the heat supplied to the reactor 1
On Figures aye, 11b has been shown the condition of
the substrate in the case where the three combined effects
of gas recirculation, the flux and reflex motions of the
substrate and the movements of the chains 9 are applied
The flux and reflex or back and worth motion of the
10 body of substrate between the vessel 2 and the feed and
discharge shafts I, 4 is achieved by means ox the hydraulic
valve 11 through which the pressure ox the buggies contained
above the substrate within the fermentation vessel Z may be
raised During that time period the substrate is driven
or forced into the discharge shaft 4 and/or the feed shaft
3 (Figure aye). WnJen the pressure threshold is reached
the hydraulic valve 11 enables the iotas to evolve
towards the buffer gasometer I and the pressure prevail-
in within -the fermenta-ti on vowel 2 suddenly drops and
20 causes the substrate to flow back into said fermentation
tank to reach its initial level again (Figure byway
Moreover, the back and forth or flux and rollicks mow owns
of the substrate would induce the movements of the
chains 9 kept stiff by the weighty or heavy elements pa,
thereby breaking the top surface or cover crust of the
substrate which would build up during the mechanization.
The moistening or damping ox this broken cover crust is
effected forthwith thereby avoiding the formation of a
crust through dehydration which may clog choke or
30 obstruct the reactor with time. Moreover the chains 9 and
discs pa form preferential paths of travel for the
evolution of the buggies within the substrate
Truss under the combined effect of the recirculation
of buggies, of tune hydraulic valve and of the chains and
discs a substantial stirring of the substrate is achieved
thereby enabling same to be fluidized when the latter has
a high content of dry matters. Furthermore due to the
~;~Z5~17;3
22
buggies recirculation, the accumulation or gathering of
heavy materials settled down on-to the bottom of the
reactor may be avoided. It is thus possible to extract
through the discharge shaft 4 a substrate in the form of
a thick paste heavily loaded with dry matters
The method and the plant according to the invention
will thus make it possible to treat ~mder conditions very
favorable for achieving a good anaerobic degradation a
substrate with a small content of din matters as well as a
substrate with a high content of dry matters. It is thus
possible on the one hand it substantially decrease the bulk
or capacity of the fermentation tanks and on the other hand
to provide for better conditions ox development of the
various steps of the process of anaerobic digestion. A
substrate heavily loaded with dry matters indeed is a
very good physical support for the microbiological pupil-
anions required or -the anaerobic digestion and its buffer
capacity is improved during the fermentation. Moreover,
due to the high concentration of organic materials within
the reactor the gas production is improved and owing to a
better fixation ox the Bahamas, the methods of digestion
are made reliable and effective.
It should be understood that according to the nature
of the substrate, it is possible to merely use the effect
of the hydraulic valve combined with the chains 9 or merely
the buggies recirculation
Moreover, the pneumatic drive or forcing of the
products within the fermentation vessel 2 through a
siphon and -their discharge also through a siphon make it
possible to periodically feed the substrate to be treated
into the feed shaft 3 and to periodically remove or extract
the fermented substrate prom the discharge shaft 4 while
always keeping a body of substrate within the ~ermentat-
ion vessel 2 so as to avoid blocking the continuous
operation of the digester thereby causing the ~ermentat-
ion to stop.
Furthermore, the reactor 1 is advantageously pitted
5~l~3
23
with a heating system which will keep the tank at the
desired temperature to promote the anaerobic degradation
process and such a heating system may for instance be
integrated into the double bottom of the tank shown on
Figure 5. Moreover the reactor 1 and the various pipelines
are fully insulated thermally for limiting the energy
losses. For that purpose various heat exchangers are
provided between the fluids within the plants as shown on
Figures 7 and 8 or for instance the leaven or inoculum is
10 reheated through passing same into a digester located
upstream of the reactor 1 wherein is carried out a
preliminary treatment ox the substrate through thermos
genus aerobic degradation in order to thus optimize the
power efficiency of the plant.
Moreover, the apparatus comprises, in a known manner,
devices for measuring necessary physio-chemical values
such as gas flow, temperature, phi rho and the oxygen
concentration
