Pyrolysis system

Abstract

Pyrolysis system (1) comprising: - a reactor (10) provided with a heating body (17) and in which a pyrolysis reaction takes place, - a burner (20) configured to ensure the combustion of the pyrolysis gases by producing fumes which are distributed between a first flow (F1) redirected towards the heating body (17) of the reactor (10), and a second flow capable of being directed towards a heat recovery device, - a fan (22) arranged to supply the burner (20) with air and ensure the combustion of the pyrolysis gases, configured to rotate at a controlled speed (V2), characterized in that a mixer (12) is mounted to rotate about a longitudinal axis (AB) of the reactor (10), the speed (V1) of rotation of the mixer being inversely controlled by the controlled speed (V2) of the fan (22). Figure for the abstract: figure 1

Description

Title of the invention: Pyrolysis system

[0001] The invention relates to a pyrolysis process, in particular from organic waste for the production of a form of renewable energy, for example renewable gas or electricity. The invention also relates to a pyrolysis system for implementing the pyrolysis process according to the invention.

[0002] Pyrolysis systems generally comprise a reactor arranged vertically or horizontally, in which a pyrolysis reaction is carried out. The pyrolysis reaction is a chemical decomposition which takes place in the absence of oxygen or in an oxygen-deficient atmosphere. Reactants, called inputs, are introduced into the reactor to form useful products, including biochar and pyrolysis gases.

[0003] It is known to use part of the gases produced for heating the reactor, in particular to make the pyrolysis reaction autonomous. It is therefore important to have a compromise between the autonomy of the reaction and the quantity of product actually recovered for subsequent use.

[0004] To obtain a better yield from a reaction, it is often important to study its kinetics. The kinetics of a pyrolysis reaction depends on many factors, such as the composition of the inputs, the temperature, the operating pressure.

[0005] It is known, in particular from document CN 115 999 472, to provide a pyrolysis system comprising a reactor arranged vertically, which is equipped with a mixer whose speed is modulated to better control the kinetics of the pyrolysis reaction. This speed is modulated as a function of the thermal power supplied by the reactor, and it is calculated as a function of the temperatures inside the reactor and in an external envelope of said reactor.

[0006] The aim of the invention is to optimize the management of the kinetics of the pyrolysis reaction inside the reactor so as to optimize the autonomy of the reaction and provide energy whose recovery is facilitated by the fact that this energy is relatively stable.

[0007] To this end, the invention relates to a pyrolysis system comprising:

[0008] - a reactor provided with a heating body and in which a reaction takes place pyrolysis producing pyrolysis gases,

[0009] - a burner configured to ensure the combustion of pyrolysis gases by producing fumes which are distributed between a first flow directed towards the heating body of the reactor and a second flow capable of being directed towards a heat recovery device,

[0010] - a fan arranged to supply the burner with air and ensure the combustion of the pyrolysis gas, configured to rotate at a controlled speed,

[0011] system in which a mixer is mounted to rotate around a longitudinal axis of the reactor, the rotation speed of the mixer being inversely controlled by the controlled speed of the fan.

[0012] It is understood that the rotation speed of the mixer is determined by the speed of the fan. The faster the fan rotates, the slower the mixer rotates, and vice versa.

[0013] If, as is preferably the case, the configuration of the fan is such that the latter adjusts its speed so as to keep the temperature of the combustion fumes constant, the control of the mixer to the fan has the effect that the speed of the fan tends to remain within a relatively limited range.

[0014] As will be seen from reading the detailed description of an exemplary embodiment, a cascade control "flue gas temperature" fan", then "fan" mixer", which closes in a loop thanks to the "mixer" flue gas temperature" dependency, helps to maintain the fan speed within a limited range. In short, if the fan speed increases, it is because the flue gas temperature has increased. Reducing the mixer speed causes a drop in the production of pyrolysis gases which will help the fan to lower the flue gas temperature. Conversely, if the fan speed decreases, it is because the flue gases tend to be less hot. Increasing the rotation speed of the mixer produces more pyrolysis gases, facilitating the increase in flue gas temperature.As a result, the combined effects of the fan and the mixer stabilize the flue gas temperature while avoiding the fan having to compensate for variations in pyrolysis gas production exclusively by the air flow. This ensures the safety of the pyrolysis system, the autonomy of the pyrolysis reaction and provides stable energy facilitating its recovery.

[0015] Furthermore, the pyrolysis system may further comprise one or more of the following optional features, taken alone or in combination.

[0016] - The controlled speed is maintained at around 80% of its operating limit. operation.

[0017] If the fan reaches its operating limit (100% of its power), the flue gas temperature can no longer be regulated and an emergency shutdown of the pyrolysis system must be triggered. The controlled speed is advantageously maintained at around 80% to have significant burner power while leaving room for maneuver to regulate the temperature in the event of a sudden increase.

[0018] - The pyrolysis system further comprises an automaton configured to obtain data on the controlled fan speed in order to control the rotation of the mixer.

[0019] - The system comprises a temperature sensor arranged at the outlet of the burner for measure the temperature of the fumes and to communicate temperature data to the PLC to control the rotation of the mixer.

[0020] - The heating body of the reactor is constituted by an external jacket with double reactor wall, possibly fitted with baffles.

[0021] The baffles are formed in the outer casing for the good distribution of heat around the reactor for carrying out the pyrolysis reaction.

[0022] - The mixer comprises a structure of symmetrical or asymmetrical shape having at least one central section mounted to rotate around the longitudinal axis of the reactor, and at least two lateral sections, preferably the lateral sections are arranged to scrape an internal wall of the reactor or ensure uniform mixing of scraped particles.

[0023] The invention also relates to a pyrolysis method for regulating the rotation speed of a mixer mounted in a reactor capable of producing pyrolysis gases intended to be directed towards a burner, the method comprising the following steps:

[0024] - a step of detecting the controlled speed of a fan configured for supply the burner to ensure the combustion of pyrolysis gases, producing fumes,

[0025] - a step of determining a target rotation speed of the mixer,

[0026] - a step of controlling a change in the speed of the mixer towards the speed of determined target rotation.

[0027] Thus, it is understood that the pyrolysis method is suitable for regulating the rotation speed of the mixer as a function of the controlled speed of the fan. The method first provides a step of detecting the controlled speed of the fan. This speed can vary as a function of the temperature of the fumes at the outlet of the burner and / or as a function of the flow rate of pyrolysis gas. In particular, the controlled speed of the fan varies according to a first control loop: an increase in the temperature of the fumes at the outlet of the burner causes the fan to accelerate to maintain the temperature constant; a drop in the temperature of the fumes causes the fan to slow down (drop in the controlled speed).

[0028] When an increase in fan speed is detected, the rotational speed of the mixer is reduced to reduce the flow rate of pyrolysis gas and therefore the temperature of the fumes, which prevents the fan from having to increase its speed too much. Conversely, when a decrease in fan speed is detected, the rotational speed of the mixer is increased.

[0029] The pyrolysis process further comprises a step of returning to the detection step, provided upstream of the control step, for maintaining the speed of mixer rotation when the mixer speed matches the determined target rotation speed.

[0030] This step ensures that no change in rotation speed is made to the mixer when the pyrolysis system is in its optimal state, i.e. the system operates with constant power to ensure constant autonomy and real-time recovery in complete safety.

[0031] The pyrolysis method further comprises a step of measuring the temperature of the fumes produced by the burner, upstream or downstream of the detection step. Brief description of the figures

[0032] The invention will be better understood on reading the following description given solely by way of example and with reference to the appended drawings in which:

[0033] [Fig-1] is a diagram of a pyrolysis system according to the invention.

[0034] [Fig. 2a] and [Fig. 2b] are each a front view of a longitudinal section of a reactor.

[0035] [Fig.3] is a diagram illustrating two control loops,

[0036] [Fig.4] is a pyrolysis process diagram according to the present invention. Detailed description

[0037] [Fig.l] represents a pyrolysis system 1 for transforming inputs 2 into useful products. Here, the inputs 2 are residual household waste, for example a mixture of biomass, paper, cardboard, plastics, organic waste. The useful products are, on the one hand, char that can be used in soil fertilization or transformed into other derived products and, on the other hand, pyrolysis gas.

[0038] The pyrolysis reaction is a chemical decomposition carried out in the absence of oxygen or in an oxygen-poor atmosphere by a significant increase in temperature, for example between 350°C and 700°C.

[0039] The pyrolysis system 1 comprises a reactor 10 and a burner 20.

[0040] The reactor 10 is a cylindrical container held vertically, in which the pyrolysis reaction takes place. A heating body 17 in the form of a double-walled external envelope surrounds the reactor 10. The envelope is advantageously provided with baffles 18.

[0041] The reactor 10 has an upper opening for receiving the inputs 2. In particular, the inputs 2 are introduced into the reactor 10 by means of a buffer storage 3, for example a hopper, connected to a sealed feed device 4, for example a rotary lock or a worm screw, capable of controlling the quantity of inputs 2 introduced through the upper opening. The sealed feed device 4 is adapted to allow the introduction of the inputs 2 into the reactor 10 without allowing oxygen into the heating body, or at least a negligible amount.

[0042] The reactor 10 is equipped with a mixer 12 mounted to rotate about a longitudinal axis AB of the reactor 10 at a rotation speed VI. The mixer 12 is driven in rotation by a motor 5, preferably controlled by an automaton (not shown) configured to regulate the rotation speed VI of the mixer 12. This rotation speed VI (or stirring) of the mixer 12 makes it possible to control the kinetics of the pyrolysis reaction and to adjust the power of the pyrolysis system 1. This speed regulation will be described in more detail later.

[0043] The mixer 12 may have different structures, as illustrated in FIGS. 2a and 2b, each corresponding to an embodiment of said mixer mounted in the reactor 10, shown separately from the rest of the pyrolysis system 1.

[0044] With reference to [Fig. 2a], the mixer 12 comprises a symmetrically shaped structure having a central section 122 mounted on a shaft 11 that can be rotated by the motor 5 around the longitudinal axis AB of the reactor 10, and lateral sections 124a, 124b arranged to scrape particles of raw materials (inputs 2) stuck to the internal wall of the reactor 10 and renew the material in contact with this internal wall. Thanks to the scraping, the particles are brought towards the center of the reactor 10, which allows non-pyrolyzed particles to come into contact with the hot wall to be pyrolyzed in turn. In particular, the lateral sections 124a, 124b are each shaped like a scraper having an elongated section parallel to the longitudinal axis AB, in order to have a large area for efficient scraping of the internal wall.These scrapers or lateral sections 124a, 124b are each connected to the rotation shaft 11, in particular by rods 126, for skillful movement of all the sections 122, 124a, 124b.

[0045] In [Fig. 2b], the mixer 12 comprises an asymmetrically shaped structure with two lateral sections 124', 126' (vertical) connected by two central sections 122' (horizontal), here rods. The mixer 12 is mounted to rotate about the longitudinal axis AB in the same way as in [Fig. 2a]. Here, a first lateral section 124' forms a scraper capable of scraping the inner wall of the reactor 10 and a second lateral section 128' is arranged between the rotation axis AB and the inner wall of the reactor 10 to ensure uniform mixing of the particles which are scraped from the inner wall towards the center of the reactor 10. More particularly, the closer the second lateral section 128' is to the inner wall, the higher the torque required to rotate the mixer 12.

[0046] Furthermore, as visible in figures 1, 2a and 2b, the reactor 10 has a lower part in the form of a funnel 14, particularly adapted for the recovery of a first useful product, the tank 6. A pallet 16 is mounted on the rotation shaft 11, being arranged to scrape the internal wall of the funnel 14 in order to avoid the accumulation of char. The funnel 14 is connected to an extraction device 7 ([Fig.l]) making it possible to ensure the sealing of the reactor 10 during the recovery of the char 6.

[0047] For the second useful product, the reactor 10 is provided at its upper part with a pipe 8 for recovering the pyrolysis gases, as visible in [Fig.l]. This pipe 8 is arranged to convey the pyrolysis gases to the burner 20.

[0048] The burner 20 is configured to ensure the combustion of the pyrolysis gases and produce pyrolysis fumes. More particularly, the burner 20 comprises a combustion chamber forming an enclosure in which the combustion of the pyrolysis gases takes place. The combustion occurs at a very high temperature, between 950°C and 1300°C, and produces the combustion fumes of these pyrolysis gases.

[0049] To start and maintain combustion, outside air 222 is introduced into the burner 20 by means of a fan 22. The fan 22 is therefore configured to supply air to the burner 20 to ensure combustion with a controlled speed V2. More particularly, the fan 22 is controlled by the controller (not shown) so as to always provide sufficient outside air 222 to ensure complete combustion of the pyrolysis gases. Thus, the pyrolysis gases are completely burned at the outlet of the burner 20, which is necessary for the safety of the system 1. Preferably, an oxygen probe (not shown) may be provided downstream of the burner 20 in order to verify that the burner is operating with excess air.

[0050] The fumes at the outlet of the burner 20 are recovered in a conduit 9 arranged to redirect a first flow F1 towards the heating body 17, i.e. the double wall, of the reactor 10 and a second flow F2 towards a recovery device 30. A flow management valve 13 is provided upstream of the recovery device 30 to regulate the quantity of fumes sent in the first flow F1. The control of this valve 13 will not be described here.

[0051] The first flow F1 of fumes redirected towards the heating body of the reactor 10 ensures the maintenance of the heat environment necessary for carrying out the pyrolysis reaction, thus optimizing the autonomy of the reaction.

[0052] Concerning the second flow F2, the fumes enter the recovery device 30 at high temperature, approximately 800°C, and exit cooled to a temperature between 100°C and 200°C. The energy recovery can be of several types: thermal, thanks to an exchanger and a heat distribution network, electrical thanks to a “Stirling” type engine, cold thanks to an exchanger and an adsorption cooling unit.

[0053] In the example of [Fig.l], the fumes are cooled by passing through an exchanger 30, itself integrated into a cooling loop 32. This cooling loop 32 operates with water 321 in a closed circuit. The water 321 is put into movement in the circuit by a pump 322, it is heated in the exchanger 30 to cool the fumes, and an air cooler 323 is provided to assist in the cooling of the water 321. The cooled and ultimately unusable fumes are sucked from the exchanger 30, by means of an extractor 34, towards a fume scrubber 36 making it possible to reduce air pollution, before being discharged into the atmosphere through a chimney 38.

[0054] Thus, from the thermal energy produced by the burner 20, the first flow F1 is used to make the process autonomous by a continuous heat supply, while the second flow F2 is used for constant and continuous energy recovery.

[0055] This recoverable energy is intended to be used in real time, because in the case of electrical recovery it is not storable, and in the case of thermal recovery storage involves significant losses. Consequently, in order to be able to guarantee energy recovered in real time while ensuring an efficient heat supply of the reactor 10, it is preferable that the energy produced by the burner 20 is kept as constant as possible.

[0056] The power of the burner 20 depends on the calorific value and the flow rate of the pyrolysis gas at the outlet of the reactor 10. The calorific value of the pyrolysis gas is relatively stable, for example between 14 and 18 MJ / Kg (megajoules per kilogram). The power of the burner 20 can therefore be controlled as a function of the flow rate of pyrolysis gas which depends directly on the kinetics of the pyrolysis reaction.

[0057] During combustion with excess air and at constant power, the more air is added, the more the flame temperature decreases. It is therefore possible to impact the flame temperature, and therefore the combustion and flue gas temperature at the outlet of the burner 20, by modifying the flow rate of outside air 222 at the inlet of the burner 20, in particular by the fan 22. Varying the controlled speed V2 of the fan therefore makes it possible to vary the flue gas temperature at the outlet of the burner 20.

[0058] For good combustion quality, the oxygen level in the excess air should ideally be between 5% and 15%. The fan 22 is configured to provide an outside air flow 222 so as to maintain the oxygen level in this flow greater than 5%.

[0059] In addition, the fan 22 is configured to maintain the temperature at the outlet of the burner 20 at a predetermined constant value. Maintaining the temperature constantly is important on the one hand to have good combustion quality, and on the other hand to meet the safety constraints linked to the materials used downstream of the burner 20, in particular from the burner 20 to the reactor 10 or to the recovery device 30. In particular, these materials are adapted to accept a maximum temperature of 1100°C. Preferably, the temperature at the outlet of the burner is maintained between 800°C and 1000°C. At the outlet of the burner 20, a temperature sensor 24 measures the temperature of the combustion fumes. The controller uses this information to control the acceleration or deceleration of the fan 22, in a first control loop: an increase in the temperature of the fumes at the outlet of the burner 20 causes an acceleration of the fan 22 (increase in speed V2); a drop in the temperature of the fumes at the outlet of the burner 20 causes the fan 22 to slow down (decrease in speed V2).

[0060] The temperature of the fumes at the outlet of the burner 20 depends on the power of the burner 20, which depends on the flow rate of pyrolysis gas, itself directly dependent on the kinetics of the pyrolysis reaction.

[0061] A large number of parameters influence the kinetics of the reaction and therefore the flow rate of pyrolysis gas: temperature, pressure, type of input, particle size, filling rate of the reactor 10, distribution of the inputs in the reactor 10. The mixer 12 has several effects on the distribution of the inputs in the reactor 10. It makes it possible to promote the heat transfer from the casing to the inputs 2 by renewing the material in contact with the internal wall of the reactor 10, in particular thanks to its lateral sections 124a, 124b, 124' scraping the internal wall of the reactor 10. It also makes it possible to promote the heat transfers between the inputs 2 inside the reactor 10 by increasing the contact areas. Therefore, the higher the rotation speed VI of the mixer 12, the more the pyrolysis reaction kinetics are favored, the higher the pyrolysis gas flow rate and therefore the higher the power of the burner 20.Conversely, the lower the rotation speed VI of the mixer 12, the lower the power of the burner 20. That said, here, the drop in speed VI does not affect the feasibility of the pyrolysis reaction in the reactor 10. Indeed, the mixer 12 is advantageously maintained at an optimal speed, in order to ensure a certain stability of the burner 20.

[0062] Thus, the rotation speed VI of the mixer 12 makes it possible to vary the flow rate of pyrolysis gas. The quantity of gas / air mixture in the burner 10 will therefore also vary and with it the combustion temperature. The regulation of the fan 22 will make it possible to adjust the air flow rate to maintain the combustion temperature stable, in particular around a desired safe temperature. Consequently, the rotation speed VI of the mixer 12 has an indirect effect on the controlled speed V2 of the fan.

[0063] According to the first control loop described above, an increase in temperature at the outlet of the burner 20 causes an acceleration of the fan 22 to cool the fumes. Such an increase means that an increase in the gas flow rate has occurred.

[0064] However, it is preferable to maintain the controlled speed V2 of the fan 22 stable for safety reasons. Indeed, the fan 22 keeps the flue gas temperature stable; if it reaches its operating limit (100% of its power), the temperature can no longer be adjusted and an emergency shutdown of the pyrolysis system 1 must be triggered. Preferably, the speed of the fan V2 is kept at around 80%. In addition, keeping the fan 22 stable means that the power of the burner 20 and the recovery system is also stable.

[0065] According to the invention, a second control loop controls the rotation speed VI of the mixer 12 to the controlled speed V2 of the fan 22. Such stability of the controlled speed V2 makes it possible to avoid a runaway of said fan 22, and to obtain a smooth curve of the recovery.

[0066] For this purpose, the automaton uses the information of the controlled speed V2 of the fan 22 to control the rotation speed VI of the mixer 21. An acceleration of the fan 22 causes a drop in the rotation speed VI of the mixer 12, and a deceleration of the fan 22 causes an increase in the rotation speed VI of the mixer 12.

[0067] In particular, the combination of the two control loops can be summarized as illustrated in [Fig.3]:

[0068] - external disturbances 50 cause a variation 51 of the gas flow rate of pyrolysis (1st physical phenomenon),

[0069] - a variation 51 of the pyrolysis gas flow rate causes a variation 52 of the temperature combustion temperature (2nd physical phenomenon),

[0070] - a variation 52 in combustion temperature causes a variation 53 of the controlled speed V2 of fan 22 for maintaining constant temperature 54 (first control loop),

[0071] - a variation 53 of the controlled speed V2 of the fan causes a variation 55 of the rotation speed VI of the mixer 12 (second control loop),

[0072] - a variation 55 of the rotation speed VI of the mixer 12 causes a variation 51 of the pyrolysis gas flow rate (1st physical phenomenon), etc.

[0073] Thus, a feedback loop is obtained, according to which the rotation speed V1 of the mixer 12 is controlled to the constant maintenance of the controlled speed V2 of the fan 22, in particular for the constant maintenance of the power of the burner 20.

[0074] Preferably, the controlled speed V2 of the fan 22 is maintained at around 80%. This allows for significant power while leaving room for maneuver to regulate the temperature in the event of a sudden increase. The temperature at the outlet of the burner 20 is preferably maintained between 900 and 1000°C, which allows for good combustion of the pyrolysis gas while ensuring the safety of the system 1. This results in a power of the burner 20 of around 150 to 200 kW (kilowatt).

[0075] Advantageously, a speed variator (not shown) of the fan 22 is provided to communicate the controlled speed V2 of the fan 22 to the automaton which uses this information to control the regulation of the rotation speed VI of the mixer 12. The automaton is configured to determine the speed at which the mixer 12 must operate.

[0076] [Fig.4] illustrates a pyrolysis method 100 for regulating the speed (VI) of the mixer 12, the method comprising:

[0077] - a detection step 110 of the controlled speed V2 of the fan 22,

[0078] - a step 120 of determining a target rotation speed of the mixer 12, and

[0079] - a control step 130 of a change in the speed of the mixer 12 towards the determined target rotation speed.

[0080] Furthermore, the method provides a return step 140 to the detection step 110, provided upstream of the control step, for maintaining the rotation speed V1 of the mixer 12, when the rotation speed VI of the mixer 12 corresponds to the determined target rotation speed.

[0081] Furthermore, depending on the measured speed of the fan 22, the rotation speed VI of the mixer 12 is increased or reduced. More particularly, when an increase in speed of the fan 22 is measured, the mixer 12 is slowed down. When a decrease in speed of the fan 22 is measured, the mixer 12 is accelerated.

[0082] The invention is not limited to the embodiments presented and other embodiments will become clear to those skilled in the art. It is in particular possible to modify the structure of the mixer 12, to modify the temperature and power levels involved in the pyrolysis system. The pyrolysis method may further comprise a step of measuring the temperature of the fumes produced by the burner, upstream or downstream of the step of measuring the fan speed. List of references

[0083] AB: longitudinal axis of the reactor Fl: first stream F2: second stream V1: mixer rotation speed

[0084] V2: controlled fan speed

[0085] 1: pyrolysis system 2: entrants

[0086] 3: buffer storage 4: Waterproof power supply device 5: engine 6: first useful product, biochar

[0087]

[0088]

[0089]

[0090]

[0091] 7: extraction device 8: driving 9: conduit 10: reactor 11: rotation shaft 12: mixer 122, 122': central section 124a, 124b, 124', 128': lateral section 126: stem 13: flow management valve 14: lower part in funnel 16: palette 17: heating body 18: chicanes 20: burner 22: fan 222: outside air 24: temperature sensor 30: recovery device 32: cooling loop 321: water 322: pump 323: air cooler 34: extractor 36: smoke scrubber 38: chimney 50: external disturbances 51: variation of the pyrolysis gas flow rate 52: variation of combustion temperature 53: controlled fan speed variation 54: constant temperature maintenance 55: variation of the mixer rotation speed 100: pyrolysis process 110: detection step 120: determination step 130: a command step 140: return step

Claims

Claims

1. Pyrolysis system (1) comprising: - a reactor (10) provided with a heating body (17) and in which a pyrolysis reaction takes place, - a burner (20) configured to ensure the combustion of the pyrolysis gases by producing fumes which are distributed between a first flow (F1) redirected towards the heating body (17) of the reactor (10), and a second flow (F2) capable of being directed towards a heat recovery device, - a fan (22) arranged to supply the burner (20) with air and ensure the combustion of the pyrolysis gases, configured to rotate at a controlled speed (V2), characterized in that a mixer (12) is mounted to rotate about a longitudinal axis (AB) of the reactor (10), the speed (VI) of rotation of the mixer being inversely controlled by the controlled speed (V2) of the fan (22).

2. Pyrolysis system (1) according to the preceding claim, in which the controlled speed (V2) of the fan is maintained at around 80% of its operating limit.

3. Pyrolysis system (1) according to any one of the preceding claims, further comprising an automaton configured to obtain data on the controlled speed (V2) of the fan so as to control the rotation of the mixer (12).

4. Pyrolysis system (1) according to the preceding claim, comprising a temperature sensor (24) arranged at the outlet of the burner (20) to measure the temperature of the fumes and to communicate temperature data to the automaton to control the rotation (VI) of the mixer (12).

5. Pyrolysis system (1) according to any one of the preceding claims, in which the heating body (17) of the reactor (10) is constituted by a double-walled external casing of the reactor, optionally provided with baffles.

6. Pyrolysis system (1) according to any one of the preceding claims, in which the mixer (12) comprises a structure of symmetrical or asymmetrical shape having at least one central section (122, 122') mounted in rotation around the longitudinal axis (AB) of the reactor (10), and at least two lateral sections (124a, 124b, 124', 128'), preferably the lateral sections (124a, 124b, 124', 128') are arranged to scrape an internal wall of the reactor (10) or ensure uniform mixing of scraped particles.

7. Pyrolysis method for regulating the speed (VI) of a mixer (12) mounted in a reactor (10) capable of producing pyrolysis gases intended to be directed towards a burner (20), comprising: - a step of detecting (110) a controlled speed (V2) of a fan (22) configured to supply the burner (20) to ensure the combustion of the pyrolysis gases while producing fumes, - a step of determining (120) a target rotation speed of the mixer (12), - a step of controlling (130) a change in speed of the mixer (12) towards the determined target rotation speed.

8. Pyrolysis method according to the preceding claim, further comprising: - a return step (140) to the detection step (110), provided upstream of the control step (130) when the speed (VI) of the mixer corresponds to the determined target rotation speed.

9. Pyrolysis method according to any one of claims 7 or 8, further comprising: - a step of measuring the temperature of the fumes produced by the burner (20), upstream or downstream of the detection step (110).

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