Technical Field

The present invention relates to an apparatus and method for the processing of waste material.

Background Art

In particular, the apparatus according to the present invention is able to transform waste material, irrespective of its nature, into an inert material and, in the event of its containing organic parts, into syngas.

To date, the need is strongly felt to identify waste disposal methods, preferably with the recycling of energy, which at the same time have a low environmental impact.

To date, to dispose of waste, methods are used that envisage heating to high temperature aimed at bringing the waste to a plasma state.

In particular, following such heating, the organic components of the waste materials undergo a process of molecular breakdown which produces, by cooling, a synthetic gas containing products with low molecular weight, such as carbon monoxide and hydrogen, intended to be subsequently burned.

Any inorganic materials in the waste material, such as, e.g., metals and especially heavy metals, are not transformed into a synthetic gas but produce a liquid lava which solidifies in a vitreous matrix, also used as a building material. WO2004/087840 describes a piece of equipment of known type for the processing of waste materials which has two operating phases, in the first of which the waste material undergoes a heating and combustion process inside a furnace in which is maintained a certain degree of vacuum, thus producing a process gas and a melted mass, and where in the second phase the gaseous product undergoes refinement with breakdown of the residual complex molecules and removal of the carbon particles that have formed in the first phase by means of oxidization with dosed quantities of air and/or steam.

The methods used to date for the processing and the disposal of waste materials have high running costs, due in particular to the equipment used.

In particular, one of the limits of the known equipment consists in the high waste of energy required to keep the running temperature and the degree of vacuum substantially constant inside the furnace.

Another drawback consists in the difficulty in regulating the process parameters according to the characteristics of the waste material to be processed.

Description of the Invention

The main aim of the present invention is to provide an apparatus for the processing of waste material resulting in lower operating costs compared to the known types of apparatus and that, at the same time, has a higher energy output. Within this aim, one object of the present invention is to reduce the waste of energy required to keep substantially constant the operating temperature, the state of plasma and the degree of vacuum inside the container in which the waste material is introduced.

Yet another object of the present invention is to enable the adjustment of a number of process parameters as a function of the type of waste material introduced and of the characteristics of the gas obtained from the processing of the same.

Another object of the present invention is to provide an apparatus for the processing of waste material which allows to overcome the mentioned drawbacks of the prior art within the ambit of a simple, rational, easy and effective to use as well as low cost solution.

The above mentioned objects are achieved by the present apparatus for the processing of waste material according to claim 1.

Brief Description of the Drawings

Other characteristics and advantages of the present invention will become better evident from the description of a preferred, but not exclusive embodiment of an apparatus for the processing of waste material, illustrated by way of an indicative, but not limitative example in the accompanying drawings wherein:

Figure 1 is a cross section view of an apparatus according to the invention.

Embodiments of the Invention

With particular reference to such illustration, it is globally indicated by reference number 1 an apparatus for the processing of waste material.

The apparatus 1 comprises a container 2 defining a processing chamber 3 having at least an inlet port 4 for the waste material to be processed and at least an outlet port 5 for a process gas obtainable from the processing of the waste material itself.

The apparatus 1 comprises supply means 6 of the waste material inside the container 2 through the inlet port 4.

The inlet port 4 is preferably arranged at the upper portion of the container 2. More in particular, the supply means 6 comprise at least a first duct 7 which crosses the inlet port 4 and substantially arrives at the median zone of the processing chamber 3.

In the embodiment shown in figure 1, inside the first duct 7 a worm screw 8 is arranged which can be operated to cause the forward movement of the waste material, which is introduced through a hopper 9, along the duct itself.

In an alternative embodiment, not shown in the illustrations, the supply means 6 comprise a duct with a re-closable door inside which is housed in a sliding way a sort of drawer which is also re-closable, intended to house the prepackaged waste material to be processed, and an actuator element which can be operated to push the above-mentioned drawer towards the re-closable door.

Advantageously, the wall which delimits the container 2 has at least three layers adjacent to one another.

More in particular, the wall delimiting the container 2 has an inner layer able to absorb heat and allow infrared rays to pass through, e.g. with carbide base such as silicon carbide, boron carbide and titanium carbide, an intermediate layer able to reflect the infrared rays, e.g., mullite- and spinel-based, and an outer layer, also able to absorb heat, made up of single component oxides, e.g., with alumina, zirconium, titanium, magnesium oxide base.

Suitably, the outer layer is associated with a metal layer defining the outer surface of the container 2.

The apparatus 1 then comprises means for depressurizing (not shown in detail in the illustrations) the processing chamber 3 to a predefined degree of vacuum. Such depressurizing means are able to keep such degree of predefined vacuum over time.

Also provided are heating means 10 of the processing chamber 3 to a predefined conversion temperature and ionizing means 1 1 of the processing chamber itself by means of electric discharges, where the ionizing means 11 are distinct from the heating means 10.

The conversion temperature is generally between 1500°C and 2000°C, preferably between 1600°C and 1700°C.

The combined action of heating due to the heating means 10 and of ionizing due to the ionizing means 11 causes the transformation of the waste material into a process gas and into a residue that is collected on the bottom of the processing chamber 3.

Preferably, inside the processing chamber 3, a mass of inert material 12 is arranged, e.g., silica, which collects on the bottom portion of the container 2 and defines a liquid head 13.

The purpose of such mass of inert material 12 is to incorporate the above- mentioned residue containing the inorganic components and the heavy metals present in the waste material, so as to form a liquid lava mass.

Suitably, the supply means 6 also comprise a second duct 14 arranged at the bottom portion of the container 2 and through which the waste material in liquid and/or gaseous state is introduced inside the processing chamber 3 below the liquid head 13.

At the bottom of the container 2 an outlet mouth 15 is also provided for the liquid lava mass, where such outlet mouth 15 can be opened after the liquid head 13 has exceeded a predefined level.

More in particular, inside the processing chamber 3 are arranged ultrasonic sensor means 16, arranged at the top of the processing chamber itself and able to detect the level of the liquid head 13.

Advantageously, the heating means 10 comprise at least a superconductor 10a, e.g., of the high-temperature type (SAT), connected to a resistor 10b and supply means of the electric current to the superconductor itself (not shown in the illustration). The superconductor 10a is therefore able to conduct electric current to the resistor 10b, reducing to the utmost the heat dispersions by effect of its superconducting properties and at the same time allowing the use of cables of reduced diameter. The resistor 10b, due to overheating following the high amount of electric current crossing through it, causes a rise in temperature inside the processing chamber 3 up to the predefined conversion temperature. Preferably, the heating means 10 comprise at least a pair of superconductors 10a connected to the opposite ends of a resistor 10b.

More in particular, the superconductors 10a are arranged at least in part outside the container 2 and the resistors 10b are arranged at least in part below the liquid head 13.

In the event of a stretch of the superconductors 10a being arranged inside the container 2 to make the connection with the relative resistor 10b, such stretch has a covering 10c, e.g. of ceramic material, to protect the superconductor itself from the high temperatures inside the processing chamber 3.

The ionizing means 11 comprise at least a pair of electrodes 11a and means for applying a difference in potential to the electrodes themselves, the latter not being shown in figure 1.

According to the invention, the electrodes 11a are arranged above the liquid head 13, so as to produce the electric discharge needed to ionize the gas and thus obtain the plasma state, and the means for applying a difference in potential are able to define a pulsating and high-frequency electric current, preferably not below 2000 Hz/sec, between the electrodes 11a.

The electric discharges which occur between the electrodes 11a cause the molecular dissociation of the gas and the consequent separation of the organic molecules from the inorganic ones.

The difference in potential applied to the electrodes 11a thus produces a voltaic arc distinguished by a high frequency.

Preferably, the electrodes 11a are arranged converging downwards the one to the other, in such a way that the electric discharge generated by the difference in potential applied to them only occurs between the two lower extremities, i.e., between the two extremities nearest to one another.

Because the electrodes 11a are generally of the expendable type, the apparatus 1 suitably also comprises means for substantially keeping constant the distance between their lower extremities.

Such means are able to cause the electrodes 11a to move forward in a direction of reciprocal approach, e.g., at predefined time intervals chosen according to the speed at which they are consumed once the process starts. Alternatively, sensor means can be provided able to detect the distance between the lower extremities of the electrodes 11a and operatively connected to the means to keep constant the distance of such extremities.

Above the electrodes 1 la a divaricating element 17 is positioned able to protect the electrodes themselves from falling waste material.

More in detail, such divaricating element 17 is cone shaped, with the converging part turned upwards, and has one or more openings (not visible in detail in figure 1) able to allow the transit of the waste material.

Advantageously, the apparatus 1 also comprises a labyrinthine duct 18 for the process gas, arranged inside the processing chamber 3 and passing through the outlet port 5. The labyrinthine duct 18 is therefore able to conduct outwards the process gas that forms with the processing of the waste material.

More in particular, the labyrinthine duct 18 defines a plurality of channels 18a, 18b communicating with one another and which extend substantially vertically. In the embodiment shown in the illustrations the labyrinthine duct 18 has at least a descending channel 18a, able to convey downwards the process gas that collects in the upper portion of the processing chamber 3, and at least an ascending channel 18b, communicating with the descending channel 18a and able to convey upwards the gas that crosses the descending channel itself.

The channels 18a and 18b are therefore communicating with one another at respective lower sections. In particular, the wall 19 which separates the descending channel 18a from the ascending channel 18b has an opening 20 defined at its lower extremity, such opening 20 being arranged above the liquid head 13 and in any case at the lower portion of the processing chamber 3.

Suitably, both the descending channel 18a and the ascending channel 18b have a substantially annular shape and are substantially concentric with one another, where the descending channel 18a is arranged externally to the ascending channel 18b.

In the central area 21 of the processing chamber 3, i.e., in the area arranged inside the wall that delimits the descending channel 18a, are arranged the lower extremities of the electrodes 11a. The process gas that generates following the processing of the waste material therefore rises up inside the processing chamber 3 along the central area 21, and collects up in its upper portion, after which it enters the labyrinthine duct 18.

Advantageously, the apparatus 1 also comprises detection means 22 of the spectrum of the process gas coming out of the outlet port 5.

Such detection means 22 are operatively connected to a control and command unit (not shown in the illustrations), which has a programmable memory in which a reference spectrum can be pre-set, e.g., that of natural gas, and which is programmed to compare the process gas spectrum detected from time to time with the pre-set reference spectrum.

The control and command unit is also operatively connected to the supply means 6 of the waste material and to the means for applying a difference in potential to the electrodes 11a.

Preferably, the control and command unit is able to intervene on the supply means 6 and/or on the means for applying a difference in potential in the event of the detected spectrum being different from that of reference.

More in particular, the control and command unit is programmed to intervene on the means for applying a difference in potential, so as to change the intensity of the current between the electrodes 11a, in the event of the variation between the detected spectrum and that of reference being below a reference value between 15% and 20%, and to intervene on the supply means 6, so as to vary the quantity of treated waste material, in the event of the difference between the two spectrums exceeding the above-mentioned reference value.

Advantageously, downstream of the outlet port 5 gas cooling means are arranged, not shown in the illustrations, able to avoid the formation of harmful long molecular chain compounds such as dioxins and furans.

The operation of the present invention is as follows.

The waste material is from time to time introduced inside the processing chamber 3 by means of the supply means 6 and, more specifically, through the first duct 7 in the event of the waste material being substantially solid or through the second duct 14 in the event of its being of the liquid and/or gaseous type.

As has already been said, the waste material that enters the processing chamber 3 undergoes a heating phase and, at the same time, an ionization phase, the combined action of which produces a redistribution of atoms/molecules such as to generate a process gas and a substantially liquid residue.

In particular, the electric discharges generated by the electrodes 11a cause the ionization of the gas, with the consequent formation of a state of plasma, and the dissociation of the relative molecules.

The process gas already forms during the drop of the waste material towards the liquid head 13 and mainly consists of carbon monoxide, hydrogen, carbon dioxide, nitrogen and water, characteristic compounds of a synthetic gas able to be converted into an energy production system.

The process gas that develops following the processing of the waste material rises along the central area 21, and collects in the upper part of the processing chamber 3, before entering inside the labyrinthine duct 18.

More in particular, the gas enters the descending channel 18a and proceeds inside it towards the lower portion of the processing chamber 3, i.e., towards the area where the temperature is highest. This way, the process gas undergoes further purification, and is cleaned of any remaining dross.

The gas then passes through the opening 20 and enters the ascending channel 18b again proceeding towards the upper portion of the processing chamber 3 and then exiting on the outside the container 2.

The process gas that exits from the outlet port 5 is then cooled to prevent the formation of the harmful compounds as described above. Preferably, the cooling process causes a drop in temperature, from about 800°C-900°C to about 80°C in approximately 0.5 seconds.

Following cooling, the process gas is analyzed by the detection means 22. The operating and control unit operatively connected to the detection means 22 then compares the detected spectrum with the reference spectrum and intervenes on the supply means 6 or on the intensity of the current generated between the electrodes 1 la so as to conform the process gas spectrum to that of reference. The liquid residue on the other hand is instead mainly made up of inorganic material, is similar to a lava with high specific weight, and collects up on the bottom of the processing chamber 3 mixing with the mass of inert material 12. As soon as the sensor means 16 detect that the liquid head 13 has risen above the preset level, the outlet mouth 15 is opened so as to allow a part of the liquid mass to come out.

It has in practice been ascertained how the described invention achieves the proposed objects and in particular the fact is underlined that the apparatus forming the subject of the present invention permits processing, in an effective and safe way, the waste material introduced into the apparatus itself.

In particular, the synergic action of heating and ionization, achieved by relative means, distinct the one from the other, permits optimizing the processing of the waste material into a process gas and a liquid residue.

Again, the presence of a labyrinthine duct able to conduct the process gas towards the outside of the apparatus permits optimizing the purification of the gas itself, inasmuch as it forces its flow through the lower part of the processing chamber, where the highest temperature is to be found.

Last but not least, the pulsating and high-frequency current generated between the electrodes permits obtaining a substantially continuous voltaic arc and, consequently, a strong ionization of the processing chamber at a low running cost, as well as the molecular dissociation of the gas which results in greater purity of the process gas thus obtained.