Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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METHOD AND PLANT FOR DISPOSING OF WASTES COMPOSED OF
PLASTIC MATERIALS OR BIOMASSE S
The present invention relates to a method and a
plant for the disposal of solid waste, consisting of
plastic or biomass materials, and liquids, particularly
consisting of vegetable oils and exhausted fats, as well
as of all organic materials which contain carbon in their
molecules.
Waste disposal is a serious problem, as it is
increasingly difficult to find areas for landfill, and
incineration has a high cost and, if not done correctly,
can lead to environmental pollution.
Treatment plants, known as waste-to-energy plants,
have established themselves, which use plastic materials
as fuel to produce heat and also biomass treatment plants
which, through fermentation, produce fuel gas.
Document WO-A1-2016/006010 describes an installation
and a method according to the preamble of the independent
claims.
In a first preferred embodiment, the present
invention proposes a new procedure for the disposal of
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plastic materials, biomass and vegetable oils and
exhausted fats, which makes it possible to obtain fuel
gas by means of a pyrolysis treatment.
The present invention therefore proposes a method
and systems for implementing said method as claimed in
the respective independent claims.
The method essentially consists in subjecting the
solid and liquid waste to be disposed of to a pyrolysis
treatment that allows the extraction of fuel synthesis
gas (syngas), obtaining an inert residue that does not
cause problems for landfill disposal.
In this embodiment, the plant substantially
comprises:
= a first section in which the pyrolysis of waste
materials takes place and synthesis gas (syngas) and
residual ash are produced;
= a second section in which the lighter fraction of
said ash, i.e. the coal dust or carbon black which
is transported by the syngas, is separated from said
syngas;
= a third section in which the fractional distillation
of the pyrolysis products takes place, obtaining
high-boiling hydrocarbons, i.e. a bituminous residue
(tar);
= a fourth section in which the bituminous residue of
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said fractional distillation is recycled, for
further treatment, said bituminous residue being
able to be mixed with said liquid waste; and
= a fifth final emergency section, which will include,
in addition to the safety pumps that will
automatically intervene in the event of a system
failure, all the safety systems.
The pyrolysis chamber basically consists of a
special steel tube heated and equipped with a mechanized
system for the movement and controlled advancement of the
solid mass to be subjected to the pyrolysis treatment.
The tube is externally insulated with ceramic fabric and,
by means of a motor-reducer unit, is made to rotate
slowly around its own axis.
A feature of the system is that it is energetically
self-sufficient, as it uses part of the fuel gas produced
to power an internal combustion engine that drives an
alternator that supplies the electricity used to heat the
pyrolysis chamber and to operate all necessary devices to
the operation of the plant.
The use of the method and the plant according to the
invention ultimately allows the transformation of solid
and liquid waste into a combustible gas and inert
residues. Part of the combustible gas is used to produce
the energy necessary for the operation of the entire
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plant, while the residual inert fraction, with a volume
much lower than that of the initial mass of the waste,
can be disposed of in landfills without particular
problems, both for reduced quantity of said ashes, both
because they are not polluting.
In a second preferred embodiment, the present
invention relates to a method and an industrial plant for
the production of methane gas from materials containing
organic carbon.
The plant and the method are able to gasify all
organic materials essentially creating a new type of slow
wet pyrolysis in an electromagnetic field and without any
emissions into the atmosphere.
Pyrolysis is a process of thermochemical
decomposition of the organic substance without the
addition of external oxygen which occurs solely due to
the effect of temperature.
The operation of the plant and method of this
embodiment is based on the principle that, when a
molecule is placed in an electric field, it orients
itself according to its dipole and, if the electric field
is repeatedly reversed, the molecule is forced to
reposition itself to each inversion of the field and this
causes a heating of the molecules which is all the more
efficient the closer the resonance frequency of the
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molecule is, but the heating still takes place even when
the frequencies are different from the resonance ones.
Also in this embodiment, the plant is made up of
five sections and is initially based, in the first
sector, on the heating of the molecules within an
electric field, until their splitting with the formation
of a synthesis gas (syngas) mainly composed of CO-0O2-H2-
02; subsequently, in the second section, the cylinder of
the first section acts as a directional antenna due to
the effect of the induced electromagnetic field, and the
molecular disorder generated by the temperature undergoes
an energetic contribution made by radiofrequency waves
and the syngas components ionize strongly, interact with
the superheated steam and create new ordered structures
which are addressed by the PLC control of the radio
frequency originating mainly CH4.
The plant is contained in a Faraday cage that
isolates it from the outside.
The main feature of the plant, in addition to having
no emission into the atmosphere, consists in that it is
energetically self-sufficient as it uses a part of the
gas produced to power an internal combustion engine or a
turbine which, by activating an alternator, supplies the
electricity used for to heat the pyrolysis chamber and to
activate all devices necessary for the operation of the
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system.
The invention will now be described, by way of non-
limiting example, according to a preferred embodiment and
with reference to the attached Fig. 1, which shows the
functional diagram of the pyrolysis system.
With reference to Ffig. 1, (1) designates a
pyrolysis plant, according to a first embodiment of the
invention, heated with high frequency currents. This
pyrolysis plant (1) includes:
= a first section (100), in which the pyrolysis of the
waste materials takes place, the synthesis gas
(syngas) is produced and the residual ashes of the
treatment are discharged;
= a second section (200), in which the lighter
fraction of said ash (coal dust or carbon black)
which is transported by the syngas, is separated
from said syngas;
= a third section (300), in which the fractional
distillation of the pyrolysis products takes place,
obtaining high-boiling hydrocarbons or bituminous
residue (tar);
= a fourth section (400), in which the bituminous
residue of said fractional distillation is recycled,
for further treatment; and
= a fifth final emergency section (not shown): this
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final section will include, in addition to the
safety pumps that will automatically intervene in
the event of a system failure, all safety systems.
This first section (100) comprises a cylinder (2),
or pyrolysis chamber, rotating around its own axis,
externally provided with insulation, for example in
ceramic fiber. An Archimedes screw finning (3) with a
surface hardened by nitriding is welded into the
cylinder.
The cylinder (2) is set in rotation by a first
motor-reduction unit (4) and is internally heated by
heating means (5), in such a way as to bring the solid
mass to be pyrolyzed at a temperature of 680 750 C.
According to a preferred embodiment, the internal
diameter of the pyrolysis chamber (2) will preferably be
between 650 and 950 mm, while the length will preferably
be between 6000 mm and 8000 mm, with a rotation at a
speed for example between 1 and 3 revolutions per minute.
Furthermore, the heating means (5) comprise two induction
generators (6) at a radiofrequency variable between 1.5
kHz and 2.5 kHz and with a power from 80 to 120 kW each,
each of which is connected to a coil (7), inside which
the pyrolysis cylinder (2) rotates slowly. The two coils
transmit the high frequency induced current created by
the two generators in such a way that the cylinder (2)
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becomes the seat of eddy currents which heat it due to
the Joule effect.
The temperature control is carried out by means of
two laser probes (not shown) placed at the entrance and
in the middle of the pyrolysis chamber (2). The two
control points each consist of three sequential survey
points.
The loading of the cylinder (2) takes place, at the
first end (2a) of the cylinder (2), by means of a hopper
(8) which feeds an auger (9) rotated by a second motor-
reduction unit (10).
The material is loaded at the entrance to the
pyrolysis chamber (2). If the waste to be treated is
solid, it is first shredded into pieces with a size of
about 1 cm and loaded by means of the screw (9) with a
compression ratio preferably from 1:150 to 1:250 and with
adjustable speed. If, on the other hand, the waste is
liquid, it is loaded into the recycling section (400), as
better specified below. The material loaded into the
hopper (8) and inserted under pressure from the screw
conveyor (9), arrives inside the cylinder (2) whose
rotation, combined with the Archimedes screw (3), pushes
it towards the second end (2b) of the cylinder (2).
In the path along the cylinder (2), at a temperature
of 680
750 C, the solid waste, mainly consisting of
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plastic materials such as polyethylene, polypropylene,
ABS, PET, polystyrene, polyurethane or biomass (wood,
sewage sludge, straw rice, etc.), undergoes pyrolysis
producing solid and gaseous compounds. The gaseous
fraction, called syngas, includes a mixture of H2, CO, 002
CH4 (volatile fraction at room temperature) and carries
high-boiling hydrocarbons, oxygenated products of various
molecular weight in the form of vapor and carbon dust
(carbon black), while the solid one includes extremely
small amounts of residual ash.
Through an opening (11), the syngas enters a
stilling chamber (12), while the residual ashes are
discharged, through a duct (13), into a container (14).
The second section (200) comprises said stilling
chamber (12) from which the syngas is conveyed, through a
first duct (15) and a second duct (16), towards a first
cyclone (17) and, respectively, a second cyclone (18).
Inside said cyclones (17) and (18), the syngas is treated
in such a way as to complete the separation from the coal
dust (carbon black) it carried, said dust being
discharged through a lower opening (17a, 18a) of the
first and second cyclone (17, 18), while from the upper
part (17b, 18b) the syngas thus purified from the carbon
black is released.
The third section (300), in which the fractional
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separation of the pyrolysis products takes place,
includes a fractional distillation column (19) composed
of various superimposed elements equipped with
condensation plates and cooling coil with regulation of
the amount of water necessary for maintaining each module
at the condensation temperature of the high-boiling
mixtures which thus leave the syngas. All condensed high
boilers are conveyed to the bottom of the column.
The syngas coming from the separator cyclones (17)
and (18) enters the lower part of the fractional
distillation column (19) through the ducts (20) and (21).
In column (19) the volatile fraction of syngas separates
from the high-boiling hydrocarbons, which form said
bituminous residue (tar), exits from the upper outlet
(22), while said high-boiling hydrocarbons come out from
the lower outlet (23). The syngas is conveyed to a blower
(not shown) which creates a slight depression in the
pyrolysis chamber (2) and sends the syngas towards the
basic and acid washing columns (not shown).
Through a conduit (24), which enters the upper part
of the column (19), cooling water is passed, said inlet
being controlled by a valve (25) and an electronic liter-
counter (not shown). The water then passes through a coil
(26) and exits, in the form of superheated steam, from a
conduit (27).
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In the fourth section (400) there is the
recirculation of the high boiling hydrocarbons exiting,
through the duct (23), from the lower part of the
fractional distillation column (19), and of the coal dust
(carbon black) extracted from the separator cyclones (17)
and (18) placed at the exit of the calm chamber (12).
The fourth section (400) comprises a pump (28) which
injects the high-boiling hydrocarbons into a turbo-mixer
(29), operated by a third motor-reducer unit (30), the
flow of the high-boiling hydrocarbons being regulated by
a valve (31).
Carbon black coming from the cyclones (17) and (18)
is introduced into the turbo-mixer (29) through a duct
(32), the flow of carbon black being regulated by a valve
(33).
Through a duct (34), liquid waste (vegetable oils
and exhausted fats) are also inserted into the turbo-
mixer (29), the liquid waste being inserted into a hopper
(35) and their flow being regulated by a valve (36).
In the turbo-mixer (29) an emulsion is produced
which, passing through a duct (37), reaches a pump (38)
which inserts it into the pyrolysis chamber (2) through a
duct (39). Through a duct (40), the superheated steam
exiting the fractional distillation column (19) is
introduced into the pyrolysis chamber (2) through the
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duct (27), the steam flow being regulated by a valve
(41).
The turbo-mixer (29) is capable of intimately mixing
the carbonaceous product coming out of the separator
cyclones and the tar extracted at the base of the
fractional distillation column (19). This mixing is
reintroduced to the inlet of the pyrolysis chamber
together with the superheated steam coming from the coils
of the fractionated separation column. The amount of
steam varies between 10% and 15% by weight of the waste
loaded into the pyrolyzer inlet. This variation is
attributable to the nature of the waste treated. This
mixing becomes very efficient with the addition of
exhausted vegetable oil, inserted in the hopper (35),
coming from separate collection, as it has excellent
dissolving properties of hydrocarbons, even at high
concentrations.
The percentage of oxygen present in the pyrolysis
chamber is continuously monitored and recorded by an
analytical instrument type SYN 100 capable of also
verifying the percentage of CO, 002, H2 and CH4 in the
syngas produced. To avoid both syngas leaks and oxygen
infiltrations into the pyrolysis chamber, the solid waste
is fed with the auger (9) at high compaction pressure and
preheated to a suitable temperature (depending on the
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type of waste) to allow formation of a plug such as to
guarantee the tightness of the system to the entry of air
and therefore of oxygen into the pyrolysis chamber (2). A
rotary valve is inserted between the loading hopper and
the auger to prevent the infiltration of air and
therefore of oxygen harmful to the pyrolysis process.
The pyrolysis chamber (2) is kept in a slight
depression by the blower which sends the syngas towards
the basic and acid washing columns, this depression being
equal to about 0.7 mbar less than the external pressure.
In the event of an emergency, the syngas produced,
after washing, is started with an emergency torch, the
induction generators are switched off and the pyrolysis
chamber is washed with nitrogen gas.
According to a further preferred embodiment, the
plant of the invention substantially comprises:
- a waste feeding system (not shown);
- a first section (100) operatively connected to the
waste feeding system and consisting of a concentric
bimetallic cylinder (2) equipped with an Archimedes screw
(3), externally insulated and slowly rotating around its
own axis;
- the cylinder (2) ends in a second section (200) in
which the thermochemical reactions are completed, and the
lighter fraction of the reaction is separated from the
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ashes and transported by the syngas in a third section
(300) in which the cooling occurs, as well as the
separation of the syngas from the high boiling products
of pyrolysis and from the bituminous residue as well as
from the residual carbon;
- a fourth washing and cleaning section (400) in
which the syngas enters, is washed and cleaned, and then
is sent for use; and
- a fifth final emergency section (not shown), this
final section including, in addition to the safety pumps
that will automatically intervene in the event of a
system failure, all safety systems.
In particular, according to the operation of this
system, the crushed solid material contained in a silos
is sent to the loading section (8) equipped with a rotary
valve and by means of an auger (9) rotated by a gearmotor
unit, the material is pressed and sent into the cylinder
together with a small amount of water which is injected
by means of a pump which will inject liquid waste into
the first section as required.
The material reaches the inside of the cylinder (2)
equipped in the initial part with a scraping system
designed to prevent the formation of lumps. The rotation
of the cylinder (2), carried out by means of a gearmotor
group, pushes the material towards the opposite side of
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the chamber, thanks to the Archimedes screw (3) contained
inside, and, during the path (300 mm each revolution of
the cylinder), all the organic part is transformed into
syngas leaving the inert ashes and any metals contained
in the fed waste on the bottom of the cylinder (2) which,
transported by the Archimedes screw (3), will reach the
end of the cylinder (2) and will fall to the bottom of
the second section (200).
The first section (100) comprises a reactor heated
by two or more generators (6) of induced currents of
adequate power and with a frequency between 1.5 and 5 KHz
so that the cylinder becomes the seat of eddy currents
which heat it by effect Joule and will bring the
temperatures inside the reactor between 650 and 750 C at
which the pyrolysis process takes place.
The generators (6) are each connected to a coil (7)
inside which the cylinder (2) rotates with a speed
determined by the PLC and calculated by the PLC according
to the transformation times of the individual matrices
introduced.
According to this preferred embodiment, the cylinder
(2) will have a diameter between 1200 and 1500 mm and a
length between 9 and 12 m, it will be equipped with a
system controlled by a gear motor suitable for its
rotation as well as a system suitable for absorption of
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expansion due to temperatures.
The cylinder (2), at its ends, will be insulated
with packing housed in a groove and kept under pressure
by a series of springs and will also have a second
nitrogen gas safety insulation system.
Inside the cylinder (2) there is a continuous
temperature control by means of thermocouples and laser
probes as well as a control of the internal pressures
which, by means of a system of vacuum pumps, maintains
the cylinder (2) and the final chamber (12) calm at a
slight depression (about 0.7 mbar) with respect to the
external atmospheric pressure, in order to prevent any
risk of explosion.
The cylinder (2) and the heating (5) and movement
and control systems are placed inside a Faraday cage (not
shown) to isolate the outside from internal induced
currents.
The syngas from the cylinder (2) is sent to the
second section (200) consisting of a stilling chamber
(12) where the thermochemical reactions induced by the
radiomagnetic waves take place and the syngas and the
lighter fractions are separated from the ashes.
The calm or ionic copulation chamber (12) is
equipped with a system of augers for the extraction of
the ashes. The PLC-controlled augers remain constantly
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full of ash which acts as a cap to prevent the escape of
gases and the entry of external air; in the final part
they will in any case be equipped with a one-way safety
valve.
The syngas is then conveyed to a third cooling and
distillation section (300) to be separated from the
condensable part and the solid part by means of a
distillation column (19) and a centrifugal separator (17,
18). This section (300) will also be equipped with a
refrigeration plant or an ORC system for recovering and
transforming heat into energy. The centrifugal separator
(17, 18) will divide the condensed and solid products
from the cooling water, and then send the condensed and
divided products at the beginning of the cycle for a
second distillation; or, the separate products will be
stored for their industrial use.
The syngas cooled below 80 C will be sent to a
fourth washing section (400) which, by means of two
cooling towers (not shown) containing a mixture of water.
weakly acidic the first one and weakly basic the second
one, in addition to a further cooling of the syngas which
is in a phase of completion of the catalysis process,
will ensure that the PH remains between the values of 6
and 7 throughout the process. Any condensed high-boiling
hydrocarbons will be separated from the water by means of
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centrifugal separators and sent back to the start of the
cycle. Subsequently, this gas passes into an activated
carbon filtration column to lose humidity; in addition to
the activated carbon, this section (400) will be equipped
with a filtering system pushed to eliminate any formation
of any pollutants present.
This gas will then be pushed by means of pumps
towards use.
As regards the fifth final emergency section
including, in addition to the safety pumps that will
automatically intervene in the event of a system failure,
all safety systems, in case of emergency the syngas
produced, after washing, is sent to a emergency; the
induction generators (6) are automatically switched off
and the pyrolysis chamber (100) and the stilling chamber
(12) are washed with a nitrogen gas.
This safety section also includes an emergency
connection system equipped with appropriate valves
suitable for conveying the gas from the pyrolysis chamber
(100) to the emergency torch in the event of a fault.
The fifth final section also includes a plant for
the production of nitrogen by separation and the relative
nitrogen reserve tank.
The invention has been described, for illustrative
and non-limiting purposes, according to a preferred
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embodiment. The skilled technician in the field will be
able to find numerous variants, all falling within the
scope of protection of the attached claims.
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