WO2023111794A1

WO2023111794A1 - Waste material pyrolysis process and plant

Info

Publication number: WO2023111794A1
Application number: PCT/IB2022/061974
Authority: WO
Inventors: Enrico Carlo FUMAGALLI
Original assignee: Quantumkore Innovation Inc.
Priority date: 2021-12-13
Filing date: 2022-12-09
Publication date: 2023-06-22
Also published as: IT202100031142A1

Abstract

A plant of waste material pyrolysis, for example for the production of biofuel, comprises: a crushing and pulverizing section configured for crushing and pulverizing the waste material; a continuous conveyor mixing oven (15) having an inlet (16A) operatively connected to the crushing and pulverizing section and placed downstream of the crushing and pulverizing section, wherein the continuous conveyor mixing oven (15) is configured for receiving the pulverized waste material, mixing it and heating it up to pyrolytic temperatures for obtaining a solid waste and a pyrolytic fluid; a refining and condensing section operatively connected to an outlet (16B) of the continuous conveyor mixing oven (15) and configured for receiving the pyrolytic fluid and separating pyrolytic vapor from other fractions of the pyrolytic fluid and condensing the pyrolytic vapor until pyrolysis oil and pyrolysis gas are obtained; a storage section comprising at least a tank for pyrolysis oil (43, 44) and a tank for pyrolysis gas (41 ) connected through pipes to the refining and condensing section.

Description

WASTE MATERIAL PYROLYSIS PROCESS AND PLANT

DESCRIPTION

Field of the invention

The present invention refers to a plant and a process of waste material pyrolysis. The present invention refers in particular but not exclusively to the conversion of waste material into biofuel, using the process of pyrolysis, with the primary purpose of ensuring a more sustainable development (decreasing greenhouse gas emissions, increasing energy efficiency, reducing traffic congestion, creating safer, healthier and more livable cities and environments, etc.).

Background of the invention

Pyrolysis is one of the main techniques for recycling and recovering waste materials in general. Pyrolysis as method for the production of biofuel is widely used and is applied to raw materials of different nature, for example waste tires, plastic mixtures, biomass/organic materials, as wood and its derivates, residues of rice processing, residues of grape harvest, solid urban waste, etc.

Pyrolysis is a thermochemical process that occurs in the absence of oxidizing agents and determines the thermal decomposition of the waste material, i.e. is a thermal degradation in non-oxidizing atmosphere. The process cannot be reversed due to the changes in the chemical composition of materials. The products of pyrolysis comprise a solid waste, liquid pyrolysis oil and gas (syngas). By varying the temperature and the heating speed products can be moved toward the gaseous form or toward the liquid form.

In this field, the Applicant has first of all observed that known plants and processes of pyrolysis are poorly efficient because they do not allow to quickly process big quantities of waste material and then to produce in relatively short times huge amounts of pyrolysis oil.

The Applicant has then observed that the cost of pyrolysis oil is still very high just because of the inefficiencies connected to its production. The Applicant has also observed that known plants and processes of pyrolysis allow to obtain low quality pyrolytic oils that, for being improved and used for example as biofuels, must undergo subsequent physical and/or chemical processes that make the production processes/plants complex and significantly increase their costs.

The Applicant has therefore set itself the goal of designing a plant and a process that allow to increase the productivity of pyrolysis oils and decrease their cost.

The Applicant has also set itself the goal of improving the quality of pyrolysis oils so that they can be used as quality biofuels without the need to subject the oil obtained from pyrolysis to subsequent processes.

The Applicant has therefore set itself the goal of producing, through pyrolysis, pyrolysis oil and possibly high value biofuel, such as to compete with non-renewable fossil fuels and possibly replace them.

Summary

In a first aspect, the invention refers to a plant of waste material pyrolysis, comprising: a crushing and pulverizing section configured for crushing and pulverizing waste material; a continuous conveyor mixing oven having an inlet operatively connected to the crushing and pulverizing section and placed downstream of the crushing and pulverizing section, wherein the continuous conveyor mixing oven is configured for receiving the pulverized waste material, mixing it and heating it up to pyrolytic temperatures for obtaining a solid waste and a pyrolytic fluid; a refining and condensing section operatively connected to an outlet of the continuous conveyor mixing oven and configured for receiving the pyrolytic fluid and separating pyrolytic vapor from other fractions of the pyrolytic fluid and condensing said pyrolytic vapor until pyrolysis oil and pyrolysis gas are obtained; a storage section comprising a tank for pyrolysis oil and a tank for pyrolysis gas connected through pipes to the refining and condensing section. In a second aspect, the invention refers to a process of waste material pyrolysis, optionally performed through the plant of the preceding aspect and/or of one or more of the following aspects.

The process of waste material pyrolysis comprises supplying the waste material along a processing path. Along said processing path the following processing steps are performed: crushing and pulverizing the waste material; mixing and heating the pulverized waste material up to pyrolytic temperatures for producing a solid waste and a pyrolytic fluid; separating pyrolytic vapor from other fractions of the pyrolytic fluid and condensing said pyrolytic vapor until pyrolysis oil and pyrolysis gas are obtained; collecting the pyrolysis oil and the pyrolysis gas in respective tanks; wherein the pulverized waste material is mixed and heated while advancing along a tract of the processing path, optionally in a continuous conveyor mixing oven.

In a third aspect, the invention refers to the use of a superacid catalyst for the production of pyrolysis oil through waste material pyrolysis, wherein pyrolysis is performed with the plant of one or more of the aspects here described and/or according to the process of one or more of the aspects here described.

In a further aspect, the plant of pyrolysis, the process of pyrolysis and the use of the superacid catalyst according to the present invention are aimed at the production of biofuel, i.e. pyrolytic oil is biofuel or biofuel is obtained from pyrolytic oil.

The Applicant has verified first of all that the invention allows to produce high quality pyrolysis oil with relatively low times and costs. In fact, the plant and in particular the mixing oven continuously and efficiently operate.

The Applicant has also verified that the invention allows to produce pyrolysis oil usable as quality biofuel without the need to subject the oil produced with the plant and according to the process of the invention to subsequent processes. In other words, the purest finished product (primary pyrolytic oil) that exits from the plant is biofuel substantially ready to use. In particular the plant and the process of the invention are able to continuously produce, from the waste material, pyrolytic oil and/or biofuel and syn-gas (as well as a part of solid waste) which are finished products, i.e. can be used as quality energy sources.

The Applicant has verified that the plant and the process according to the invention allow to obtain pyrolytic oil (primary plus other fractions) with a yield of about 65 % and with a primary pyrolytic oil yield of about. 65% pyrolysis oil, 25% syn-gas, 10% black char and residues such as iron, glass etc.

The Applicant has verified that the primary pyrolytic oil can be used as fuel without any other treatment or with little refining treatments.

Further aspects of the invention are presented below.

In an aspect, the continuous conveyor mixing oven comprises a conveyor housed in a liquefaction chamber extending between the inlet and the outlet of the continuous conveyor mixing oven.

In an aspect, dimensions of the liquefaction chamber, such as a length measured between the inlet and the outlet and/or a diameter are a function of the amount of waste material to be treated.

In an aspect, the conveyor is horizontally arranged.

In an aspect, the conveyor comprises at least an endless screw.

In an aspect, the conveyor comprises a plurality of endless screws, optionally two or three endless screws, parallel and side by side among them.

In an aspect, the continuous conveyor mixing oven comprises a cylindrical container housing the conveyor and delimiting the liquefaction chamber.

In an aspect, the cylindrical container has a longitudinal axis horizontally arranged. In an aspect, the continuous conveyor mixing oven comprises at least a motor connected to the conveyor.

In an aspect, the motor is connected to said at least an endless screw for making it rotate around a respective longitudinal axis.

In an aspect, the continuous conveyor mixing oven comprises at least a discharge opening configured for allowing the discharge of the solid waste from the liquefaction chamber.

In an aspect, the discharge opening is arranged at a lower portion of the continuous conveyor mixing oven. In an aspect, the continuous conveyor mixing oven comprises a combustion chamber arranged at least partially around the conveyor and separated from the liquefaction chamber.

In an aspect, the continuous conveyor mixing oven comprises flame supply nozzles arranged in the combustion chamber and configured for burning gases and generating heat, wherein said heat is transmitted by conduction from the combustion chamber to the liquefaction chamber.

In an aspect, the continuous conveyor mixing oven comprises a cylindrical wall arranged around the cylindrical container, wherein the combustion chamber is delimited between the cylindrical container and the cylindrical wall.

In an aspect, the cylindrical wall has a longitudinal axis horizontally arranged.

In an aspect, the combustion chamber is defined by a gap between the cylindrical container and the cylindrical wall.

In an aspect, the cylindrical container has a window provided with at least a respective door.

In an aspect, the cylindrical wall has a window provided with at least a respective door.

In an aspect, the window of the cylindrical container and the window of the cylindrical wall are facing each other and define said discharge opening.

In an aspect, the continuous conveyor mixing oven comprises at least an insulating insulation arranged around the cylindrical wall.

In an aspect, the flame supply nozzles are in fluid connection, through ducts, with the tank for pyrolysis gas for burning at least part of the pyrolysis gas produced. In this way, the efficiency of the plant/process is increased.

In an aspect, the continuous conveyor mixing oven comprises fumes discharge pipes in fluid connection with the combustion chamber.

In an aspect, the continuous conveyor mixing oven comprises a collector in fluid connection with the combustion chamber and with the fumes discharge pipes.

In an aspect, the fumes discharge pipes comprise a filter and a chimney.

In an aspect, a mover, optionally a conveyor belt, is placed after the continuous conveyor mixing oven for receiving the solid waste and moving them away.

In an aspect, the mover is parallel to the conveyor. In an aspect, the mover faces the discharge opening.

In an aspect, the mover moves along a direction opposed with respect to a direction of advancing of waste material in the continuous conveyor mixing oven.

In an aspect, the crushing and pulverizing section comprises at least a crusher, at least a dryer and at least a pulverizer.

In an aspect, the crusher, the dryer and the pulverizer are arranged in sequence.

In an aspect, the crusher, the dryer and the pulverizer are connected among them through conveyor belts.

In an aspect, the crushing and pulverizing section comprises in sequence: a first conveyor belt, a first crusher, a second conveyor belt, a second crusher, a third conveyor belt, a third crusher and a pulverizer.

In an aspect, the second conveyor belt passes through the dryer.

In an aspect, the crushed waste material is dried while it passes through the dryer.

In an aspect, a vacuum chamber of oxygen extraction and/or a nitrogen supply tank is/are operatively interposed between the crushing and pulverizing section and the inlet of the continuous conveyor mixing oven, for removing oxidizing agents before heating the pulverized waste material.

In an aspect, the vacuum chamber of oxygen extraction is located upwards of the nitrogen supply tank.

In an aspect, a dust blower is arranged downwards of the pulverizer.

In an aspect, a hopper of dust supply is located between the dust blower and an inlet of the continuous conveyor mixing oven.

In an aspect, the plant comprises an auxiliary conveyor, optionally comprising an endless screw, interposed between the hopper of dust supply and the inlet of the continuous conveyor mixing oven.

In an aspect, the auxiliary conveyor passes through the vacuum chamber of oxygen extraction and/or the nitrogen supply tank.

In an aspect, a terminal end of the auxiliary conveyor is located over the inlet of the continuous conveyor mixing oven so that dusts fall by gravity from the auxiliary conveyor in the continuous conveyor mixing oven. In an aspect, the refining and condensing section comprises a refining and condensing column having a lower inlet operatively connected to the outlet of the continuous conveyor mixing oven and an upper outlet.

In an aspect, the lower inlet is directly connected to the outlet of the continuous conveyor mixing oven.

In an aspect, the upper outlet is placed on a top of the column.

In an aspect, the refining and condensing column has a lower outlet located on a bottom of the column itself.

In an aspect, an auxiliary tank for column residue is connected to the lower outlet of the refining and condensing column.

In an aspect, the refining and condensing column comprises a plurality of condensation levels or stages arranged one above the other between the lower inlet and the upper outlet, wherein, at each of said levels or stages, the condensation of a fraction of the pyrolytic fluid occurs.

In an aspect, each level is connected to a respective storage tank.

In an aspect, the purest vapor fraction exits from the upper outlet.

In an aspect, the refining and condensing section comprises a cooled decanter in fluid connection with the upper outlet of the refining and condensing column.

In an aspect, the cooled decanter has an upper outlet connected to the tank for pyrolysis gas.

In an aspect, the cooled decanter has a lower outlet connected to the tank for pyrolysis oil.

In an aspect, it is expected to add to the waste material and/or to the pyrolytic fluid and/or to the pyrolytic vapor a catalyst belonging to the super-acid catalyst family, for reducing the activation energy and thus accelerating the chemical reactions.

In an aspect, the superacid catalyst comprises or consists of sulphated zirconium hydroxide.

In an aspect, the catalyst is added to the pyrolytic fluid in the refining and condensing column.

In an aspect, the catalyst is added in the form of a liquid and/or powder. In an aspect, the catalyst is added to the pyrolytic fluid at one or more of condensation stages, optionally at one or more of the upper stages, optionally in the last three stages before the upper outlet.

In an aspect, at least part of the superacid catalyst is retrieved from the pyrolysis oil. In an aspect, the pulverized waste material has particles (and/or the pulverizer is configured for generating particles of pulverized waste material) with an average equivalent spherical diameter between 0,5mm and 1 ,5mm, optionally between 1mm and 1 ,4mm.

In an aspect, the pulverized waste material is heated (and/or the continuous conveyor mixing oven is configured for heating the pulverized waste material) up to pyrolytic temperatures between 430°C and 570°C, optionally between 450°C and 550°C.

In an aspect, the pulverized waste material is heated (and/or the continuous conveyor mixing oven is configured for heating the pulverized waste material) with a heating speed between 5°C/min and 20°C/min, optionally between 5°C/min and 10°C/min.

In an aspect, the waste material comprises biomass/organic materials, as for example as wood and its derivates, residues of rice processing, residues of grape harvest, solid urban waste, etc.

In an aspect, the waste material comprises also inorganic materials, as for example waste/exhausted tires, plastic mixtures, etc.

Further features and advantages will become clear from the detailed description of a preferred but not exclusive embodiment of a plant and of a process of pyrolysis of waste material, preferably but not exclusively for the production of biofuel in accordance with the present invention.

Definitions

With the term “equivalent spherical diameter” dv is intended in the present text the diameter of a sphere having the same volume of the particle.

With the term “superacid catalyst” reference is made to catalysts represented by sulphates of oxides or hydroxides of elements such as zirconium, titanium, iron, manganese, rhodium, nickel, palladium and generally elements of groups 3-10 (formerly IIB-VIIIB) of the periodic table. The most commonly used are sulphates of oxides or hydroxides of titanium and zirconium, which belong to group 4 (formerly IVB). The latter may contain other metals such as platinum, tungsten, yttrium, etc. With the adjective 'continuous' referred to the continuous conveyor mixing oven, it is intended that during pyrolytic heating, the waste material is transported, i.e. there is no static accumulation in a container in which the biomass is heated. Obviously this does not mean that the plant and/or the oven cannot be momentarily stopped. For example, the oven can be stopped to discharge the solid waste from the discharge opening. The plant can also operate on a batch basis, meaning that a predetermined amount of waste material is loaded, which continuously passes from an inlet of the plant (i.e. from a first conveyor belt) and continues to the storage tanks (pyrolysis oil/biofuel and its fractions, syn-gas and waste).

Description of drawings

This description will be provided hereinafter with reference to the set of drawings, provided simply as a non-limiting example, wherein:

Figures 1 A, 1 B and 1 C are schematic views of subsequent parts of a plant according to the invention;

Figure 2 shows an enlarged portion of the part of Figure 1 B;

Figure 3 is a different sectional view of the enlarged portion of Figure 2;

Figure 4 shows an enlarged portion of the part of Figure 1 C;

Figure 5 shows a block diagram of a process according to the invention.

Detailed description

Referring to the attached schematic figures 1A, 1 B and 1 C a plant of waste material pyrolysis, for example for the production of biofuel, is identified by the reference number 1. In the examples described hereinafter, the waste material is referred to, by way of example and not limiting thereto, as waste biomass, but in general the waste material may comprise organic materials and also inorganic materials.

Figure 1 A shows a first part of the plant 1 . The waste biomass is introduced into the plant 1 through an inlet defined by a first conveyor belt 2, located at the left end of Figure 1 A, and introduced into a first crusher 3. The first crusher 3 provides for the reduction of the biomass into rough pieces. For example, the first crusher 3 is of the opposed rollers type. For example, the rough biomass pieces have an average size higher than one centimeter.

The so crushed biomass exits from the first crusher 3 and is conveyed on a second conveyor belt 4 towards a second crusher 5. During the path on the second conveyor belt 4, since the second conveyor belt 4 passes through a dryer 6, the biomass transits through said dryer 6 which provides for depriving the biomass of at least part of its humidity content.

In the second crusher 5, the biomass is reduced into smaller pieces. For example, the second crusher 5 is a pulverizing mill. For example, the pieces of biomass outgoing from the second crusher have average dimensions under a centimeter.

The biomass outgoing from the second crusher 5 is conveyed on a third conveyor belt 7 towards a third crusher 8. In the third crusher 8, the biomass is reduced in even smaller pieces. For example, the third crusher 8 is a further refining mill.

The third crusher 8 is operatively connected to a pulverizer 9 (figure 1 B) in which the biomass is transformed in a dust formed by particles with an equivalent average spherical diameter between 0,5mm and 1 ,5mm, optionally between 1 mm and 1 ,4mm.

The elements described so far are part of a first section of the plant 1 , i.e. of a crushing and pulverizing section.

A dust blower 10 is connected to the pulverizer 9 and is arranged downstream of the pulverizer 9 so as to convey the pulverized biomass to a dust supply hopper 11 . The dust blower 10 comprises a tube extending from the pulverizer 9 and ends above the hopper 11. The pulverized biomass is brought, for example through air jets, up above the hopper 11 and falls by gravity into the hopper 11 itself.

A lower opening of the hopper 11 is connected to an auxiliary conveyor 12 comprising an endless screw 12A housed in a designated carter moved by a motor 12B. The carter has an upper inlet placed in proximity to one of its ends and communicating with the lower opening of the hopper 11 and to an ending outlet located at an opposite end. The rotation of the endless screw 12A causes the transport and advancing of the pulverized biomass from the upper inlet toward the ending outlet of the auxiliary conveyor 12. The carter of the auxiliary conveyor 12 is integrated with a vacuum chamber of oxygen extraction 13 and with a subsequent nitrogen supply tank 14 so that the endless screw 12A and then also the pulverized biomass conveyed by it pass through said vacuum chamber of oxygen extraction 13 and said nitrogen supply tank 14, so as to remove oxidizing agents from the pulverized biomass.

Downwards of the auxiliary conveyor 12 a continuous conveyor mixing oven 15 is placed. The continuous conveyor mixing oven 15, better visible in figures 2 and 3, comprises a cylindrical container 16 and a cylindrical wall 17 arranged around the cylindrical container 16. The cylindrical container 16 and the cylindrical wall 17 are made of steel and are supported by a base 18, for example in reinforced concrete. The cylindrical container 16 and the cylindrical wall 17 are horizontal, i.e. with their own longitudinal axes arranged horizontally. The cylindrical container 16 is longer than the cylindrical wall 17 surrounding it and has a proximal end and a distal end, opposite to the proximal end, which protrude from the cylindrical wall 17.

The cylindrical container 16 and the cylindrical wall 17 are coaxial to each other and radially spaced so as to delimit a gap between them defining a combustion chamber 19.

The cylindrical container 16 delimits a liquefaction chamber 20 inside it, which houses a conveyor defined by three endless screws 21 , which are parallel and side- by-side. The endless screws 21 are supported outside of the liquefaction chamber 19. An end of the endless screws 21 close to the proximal end of the cylindrical container 16 is connected to a motor 22 placed on the base 18. The motor 22 is configured for making each of the endless screws 21 rotate around a respective longitudinal axis.

The cylindrical container 16 has an inlet 16A placed near its proximal end and connected to the terminal outlet of the auxiliary conveyor 14 through the nitrogen supply tank 14. A lower end of the nitrogen supply tank 14 opens in fact into the inlet 16A obtained in a lateral wall of the cylindrical container 16. The cylindrical container 16 has also an outlet 16B placed on its distal end, so the pulverized biomass deriving from the auxiliary conveyor 12 falls by gravity from the nitrogen supply tank 14 all the way into the cylindrical container 16 through said inlet 16A. Flame supply nozzles 23 (better visible in Figure 3) are mounted on the cylindrical wall 17, face in the combustion chamber 19 and are configured for burning gases and generating heat, wherein said heat is transmitted by conduction from the combustion chamber 19 to the liquefaction chamber 20. The flame supply nozzles 23 are in fluid connection, through ducts 24 and pumps 24A, with a gas source. The flame supply nozzles 23 supply then the gas that bums as soon as it comes out of the nozzles themselves, producing flames in the combustion chamber 19. As it will be detailed later, the gas source is constituted by a tank for pyrolysis gas (syn-gas) produced by the same continuous conveyor mixing oven 15. The flame supply nozzles 23 therefore burn at least part of the gas produced by the pyrolysis itself.

As shown in Figure 3, the cylindrical container 16 has a window 25 provided with a respective door 26 and placed at an its lower portion. Analogously, also the cylindrical wall 17 has a window 27 provided with a respective door 28 and placed at an its lower portion so that it faces the window obtained in the cylindrical container 16. Each of the doors 26, 28 comprises a pair of bulkheads that are movable (e.g. moved by respective pneumatic actuators) between a closing configuration and an opening configuration of the respective window 25, 27. Said windows 25, 27 define a discharge opening of the continuous conveyor mixing oven 15 configured for allowing the discharge of solid waste from the liquefaction chamber 20.

A conveyor belt 29 is positioned under the continuous conveyor mixing oven 15 and under said discharge opening for receiving the solid waste and removing it. In particular, in the shown embodiment, the conveyor belt 29 is placed inside a cavity 30 delimited by the base 18. An upper branch of the conveyor belt 29 is parallel to the endless screws 21 , moves along a direction opposed with respect to an advancing direction of the biomass in the continuous conveyor mixing oven 15 and is configured for receiving the solid waste that falls from the discharge opening and conveying it, for example, to an appropriate storage, not shown.

The continuous conveyor mixing oven 15 comprises an insulating insulation 15A arranged around the cylindrical wall.

Furthermore, fumes discharge pipes 31 are in fluid connection with the combustion chamber 19 for removing the fumes produced by the combustion. A collector 32 is placed above the insulated cylindrical wall 17 and receives the fumes from the pipes 31 for conveying them through a filter 33 and then towards a chimney 34 (figure 1 B). The continuous conveyor mixing oven 15 is configured for receiving the biomass pulverized, mixing it and heating it up to pyrolytic temperatures, so as to partially liquefy it and obtain the aforementioned solid waste and a pyrolytic fluid. The biomass is heated in the liquefaction chamber up to pyrolytic temperatures, for example of about 500°C and with a heating speed of about 10°C/min. The biomass heats and transforms itself while advancing from the inlet 16A towards the outlet 16B of the cylindrical container 16 through the movement of the endless screws 21 . The pyrolytic fluid exits from the outlet 16B placed on the distal end of the cylindrical container 16 with a liquid fraction and a vapor or gaseous fraction.

The distal end of the cylindrical container 16 is connected to a refining and condensing column 35 (figure 2 and 4). The refining and condensing column 35 develops vertically and has a lower inlet directly connected to the outlet 16B of the continuous conveyor mixing oven 15, an upper outlet 36 placed on a top of the column and a lower outlet 37 placed on a bottom of the column itself.

The lower outlet 37 is connected, through a respective pipeline, to an auxiliary tank 38 for a column residue. The upper outlet 36 is connected, through a respective pipeline, with a cooled decanter 39.

The refining and condensing column 35 comprises also a plurality of condensation levels or stages 35A, 35B, 35C, 35D, 35E arranged one above the other between the lower inlet and the upper outlet 36, wherein, at each of said levels or stages 35A, 35B, 35C, 35D, the condensation of a fraction of the pyrolytic fluid occurs. Each level or stage 35A, 35B, 35C, 35D, 35E is connected to a respective storage tank, not shown in the attached drawings, for a respective fraction of the pyrolytic oil.

As well visible in figures 2 and 4, the endless screws 21 exit from the terminal end 16B of the continuous conveyor mixing oven 15 and its ending portions are housed in the refining and condensing column 35.

The refining and condensing column 35 receives the pyrolytic fluid and solid and/or in biomass powder parts (not fallen through the discharge opening) that exit from the terminal end 16B of the continuous conveyor mixing oven 15. The solid and/or in biomass powder parts fall in the lower outlet 37 and are collected in the auxiliary tank 38.

The hot pyrolytic fluid rises in the refining and condensing column 35 gradually cooling. Heavier fractions of the pyrolytic fluid separate by condensation in each of the stages 35A, 35B, 35C, 35D, 35E of the column 35 (and are collected in respective tanks not shown) and from the upper outlet 36 the purest refined pyrolytic vapor exits, that is conveyed in the cooled decanter 39, the refined pyrolytic vapor is separated in primary pyrolytic oil and pyrolytic gas. The primary pyrolytic oil may be itself biofuel or may be further refined for obtaining biofuel.

The refining and condensing column 35 and the cooled decanter 39 constitute a refining and condensing section of the plant 1 .

In the last three stages 35C, 35D, 35E of the column 35 before the upper outlet 36, a catalyst comprising or consisting in sulphated zirconium hydroxide is also added to the pyrolytic fluid. The sulphated zirconium hydroxide is prepared by sulphating a precursor of amorphous zirconium hydroxide with ammonium sulphate. The zirconium hydroxide is prepared through the controlled addition of an aqueous solution of zirconium oxychloride (ZrOCl2-8H2O) to a buffer solution NH4OH (2M)/NH4CI (2M) for keeping the pH at a constant value of 10,5. The solid is filtered and accurately washed with distilled water for removing chlorides. The zirconium hydroxide is then suspended in an aqueous solution of ammonium sulphate 1 N (20 ml solution/g of sample of Zr hydroxide). The mixture is stirred for 2 hours, slowly evaporated to dryness and finally limed in dry air at 450°C for 3 hours before use. The surface area of the sample is of 210 m²/g and the sulphate content is about 2 groups per nm² At least part of the superacid catalyst is retrieved from the pyrolysis oil (from the purest one (primary pyrolytic oil) and/or from one or more of its fractions collected from the last three stages).

The pyrolysis gas exits from an upper outlet 40 of the cooled decanter 39 and is collected in a tank for pyrolysis gas 41 . The ducts 24 previously mentioned that bring the gas to the flame supply nozzles 23 are connected to the tank for pyrolysis gas 41 or directly to the upper outlet 40 of the cooled decanter 39.

The pyrolysis oil exits from a lower outlet 42 of the cooled decanter 39 and is collected in a tank for pyrolysis oil 43, i.e. for the finished product. For example, more plants 1 such as the one described so far can be installed on a same site and, possibly, from the tank for pyrolysis oil 43 of each plant 1 the finished product is sent and collected in a general tank 44 of higher dimensions through a lift pump 45.

List of elements

1 plant

2 first conveyor belt

3 first crusher

4 second conveyor belt

5 second crusher

6 dryer

7 third conveyor belt

8 third crusher

9 pulverizer

10 dust blower

11 hopper

12 auxiliary conveyor

12A endless screw

12B motor

13 vacuum chamber of oxygen extraction

14 nitrogen supply tank

15 continuous conveyor mixing oven

16 cylindrical container

16A inlet

16B outlet

17 cylindrical wall

18 base

19 combustion chamber

20 liquefaction chamber

21 endless screws

22 motor

23 flame supply nozzles 24 ducts

24A pumps

25 window

26 door

27 window

28 door

29 conveyor belt

30 cavity

31 pipes

32 collector

33 filter

34 chimney

35 refining and condensing column

35A, 35B, 35C, 35D, 35E column levels or stages

36 upper outlet

37 lower outlet

38 auxiliary tank

39 cooled decanter

40 upper outlet

41 tank for pyrolysis gas

42 lower outlet

43 tank for pyrolysis oil

44 general tank

45 lift pump

Claims

1. Process of waste material pyrolysis performed through a plant of waste material pyrolysis, wherein the plant comprises: a crushing and pulverizing section configured for crushing and pulverizing waste material; a continuous conveyor mixing oven (15) having an inlet (16A) operatively connected to the crushing and pulverizing section and placed downstream of the crushing and pulverizing section, wherein the continuous conveyor mixing oven (15) is configured for receiving the pulverized waste material, mixing it and heating it up to pyrolytic temperatures for obtaining a solid waste and a pyrolytic fluid; a refining and condensing section operatively connected to an outlet (16B) of the continuous conveyor mixing oven (15) and configured for receiving the pyrolytic fluid and separating pyrolytic vapor from other fractions of the pyrolytic fluid and condensing said pyrolytic vapor until pyrolysis oil and pyrolysis gas are obtained; a storage section comprising at least a tank for pyrolysis oil (43, 44) and a tank for pyrolysis gas (41 ) connected through pipes to the refining and condensing section; wherein the process comprises: supplying the waste material along a processing path; wherein along said processing path the following processing steps are performed: crushing and pulverizing the waste material in the crushing and pulverizing section; mixing and heating the pulverized waste material up to pyrolytic temperatures in the continuous conveyor mixing oven (15) for producing the solid waste and the pyrolytic fluid; separating the pyrolytic vapor from other fractions of the pyrolytic fluid and condensing said pyrolytic vapor until the pyrolysis oil and the pyrolysis gas are obtained in the refining and condensing section; collecting the pyrolysis oil and the pyrolysis gas in the respective tanks of the storage section; wherein the pulverized waste material is mixed and heated while advancing along a tract of the processing path; wherein it is expected to add to the pyrolytic fluid a superacid catalyst, wherein the superacid catalyst is added to the pyrolytic fluid at one or more condensation stages of a refining and condensing column of the plant.

2. Process according to claim 1 , wherein the superacid catalyst is added to the pyrolytic fluid at one or more of the upper stages of the refining and condensing column.

3. Process according to claim 2, wherein the superacid catalyst is added to pyrolytic fluid in the last three stages before an upper outlet of the refining and condensing column.

4. Process according to claim 1 or 2 or 3, wherein the superacid catalyst comprises or consists in sulphated zirconium hydroxide.

5. Process according to one of claims from 1 to 4, wherein the superacid catalyst is added in the form of a liquid and/or powder.

6. Process according to one of claims from 1 to 5, wherein the pulverized waste material is heated up to pyrolytic temperatures between 430°C and 570°C and with a heating speed between 5°C/min and 20°C/min.

7. Process according to one of claims from 1 to 6, wherein the pulverized waste material has particles with an average equivalent spherical diameter between 0,5mm and 1 ,5mm.

8. Plant of waste material pyrolysis configured for performing the process according to at least one of claims from 1 to 7, the plant comprising: a crushing and pulverizing section configured for crushing and pulverizing waste material; a continuous conveyor mixing oven (15) having an inlet (16A) operatively connected to the crushing and pulverizing section and placed downstream of the crushing and pulverizing section, wherein the continuous conveyor mixing oven (15) is configured for receiving the pulverized waste material, mixing it and heating it up to pyrolytic temperatures for obtaining a solid waste and a pyrolytic fluid; 19 a refining and condensing section operatively connected to an outlet (16B) of the continuous conveyor mixing oven (15) and configured for receiving the pyrolytic fluid and separating pyrolytic vapor from other fractions of the pyrolytic fluid and condensing said pyrolytic vapor until pyrolysis oil and pyrolysis gas are obtained; a storage section comprising at least a tank for pyrolysis oil (43, 44) and a tank for pyrolysis gas (41 ) connected through pipes to the refining and condensing section; a refining and condensing column (35) having a lower inlet operatively connected to the outlet (16B) of the continuous conveyor mixing oven (15) and to an upper outlet (36); and a cooled decanter (39) in fluid connection with the upper outlet (36) of the refining and condensing column (35).

9. Plant according to claim 8, wherein the continuous conveyor mixing oven (15) comprises: a conveyor housed in a liquefaction chamber (20) extending between the inlet and the outlet of the continuous conveyor mixing oven (15), wherein the conveyor comprises at least an endless screw (21 ); a combustion chamber (19) partially arranged at least around the conveyor and separated from the liquefaction chamber (20).

10. Plant according to claim 9, wherein the continuous conveyor mixing oven (15) comprises flame supply nozzles (23) arranged in the combustion chamber (19) and configured for burning gases and generating heat, wherein said heat is transmitted by conduction from the combustion chamber (19) to the liquefaction chamber (20).

11 . Plant according to claim 10, wherein the flame supply nozzles (23) are in fluid connection with the tank for the pyrolysis gas (43) for burning at least part of the pyrolysis gas produced.

12. Plant according to claim 10 or 11 , wherein the continuous conveyor mixing oven (15) comprises: a cylindrical container (16) housing the conveyor and delimiting the liquefaction chamber (20); a cylindrical wall (17) arranged around the cylindrical container (16), wherein the combustion chamber (19) is delimited between the cylindrical container (16) and the cylindrical wall (17); wherein the 20 cylindrical container (16) has a window (25) provided with at least a respective door (26), wherein the cylindrical wall (17) has a window (27) provided with at least a respective door (28); wherein the window (25) of the cylindrical container (16) and the window (27) of the cylindrical wall (17) are facing between them and define a lower discharge opening configured for allowing the discharge of the solid waste from the liquefaction chamber (20).

13. Plant according to one of claims from 8 to 12, wherein the continuous conveyor mixing oven (15) comprises a collector (32) in fluid connection with the combustion chamber (19) and with fumes discharge pipes (31 ).

14. Plant according to one of claims from 8 to 13, wherein the crushing and pulverizing section comprises at least a crusher (3, 5, 8), at least a dryer (6) and at least a pulverizer (9) connected among them through conveyor belts (2, 4, 7).

15. Plant according to one of claims from 8 to 14, wherein a vacuum chamber of oxygen extraction (13) and/or a nitrogen supply tank (14) is/are operatively interposed between the crushing and pulverizing section and the inlet (16A) of the continuous conveyor mixing oven (15) for removing oxidizing agents before heating the pulverized waste material.