Method for producing pyrolytic oil comprising liquid hydrocarbons from plastic material using intermittent energy source, and associated machine equipment

Abstract

The invention relates to a method for producing pyrolysis oil containing liquid hydrocarbons from plastic materials, preferably waste materials. The method is characterized by the use of an energy source of preferably intermittent nature (and variable intensity), such as, for example, solar radiation. The plastic material enters a pyrolysis reactor, which is heated with a molten salt hot fluid. The molten salt is heated by the intermittent source to a temperature that is not fixed but variable within a predetermined range. Specifically, when the availability of the energy source is equal to or exceeds a predetermined maximum value, the temperature of the molten salt reaches the upper end of the range. Instead, when the availability of the energy source is equal to or lower than a predetermined minimum value, the temperature of the molten salt reaches the lower end of the range. For an intermediate availability value, the temperature may also reach an intermediate value, for example, following a linear profile. The pyrolysis temperature follows the temperature of the molten salt. On the other hand, the pyrolysis pressure is adjusted such that when the pyrolysis temperature is lower, the pyrolysis pressure is higher (at least 2.5 bar) and when the pyrolysis temperature is higher, the pyrolysis pressure is lower (no more than 2 bar). Surprisingly, it was found that, by operating in a specified manner, the quality of the obtained pyrolysis oil remains constant, even for considerable variations in pyrolysis temperature.

Description

Technical Field

[0001] The present invention relates to a sustainable process for producing pyrolysis oil comprising liquid hydrocarbons from plastic materials, preferably from waste materials.

[0002] An area of ​​application is the pyrolysis of plastic materials to produce pyrolysis oil containing hydrocarbons. After further processing, the pyrolysis oil can be converted into monomers suitable for producing polymers, thus closing the circuit. Background Art

[0003] In the chemical industry, and more specifically in the polymer industry, it is increasingly strategic not only to recycle waste polymers, but also to do so in a sustainable manner. In fact, "closed-loop" recycling processes that are "closed" from a material perspective, but not "closed" in terms of the energy required (i.e., using fossil fuels or energy ultimately derived primarily from such sources), are not truly closed, especially considering the very high amounts of thermal energy required by pyrolysis processes. Consequently, the resulting carbon footprint can be so large that it can jeopardize the effectiveness of the entire recycling loop, rendering the process no longer convenient.

[0004] Integrated solutions, such as those now proposed, not only allow the use of "green" energy, but also solve a major problem associated with the use of most renewable energy sources (such as solar or wind energy), namely the intermittent and variability of their intensity. This intermittency and variability, in turn, determines a large temporal variation in the available energy.

[0005] Most chemical processes typically require very long run times and stable process conditions in order to achieve constant product quality and become economically sustainable. This is especially important for processes like pyrolysis that require higher temperatures and larger flow rates, as they take longer to start, stop, and reach stable process conditions.

[0006] Therefore, the intermittent nature and variability of the energy source is a very serious disadvantage of any pyrolysis process known in the art.

[0007] Therefore a pyrolysis process that allows for the use of renewable energy sources, such as solar energy, but at the same time is able to manage the intermittency and variability of the energy source while maintaining the quality of the produced pyrolysis oil is desirable.

[0008] Several patent applications disclose methods for the thermal or catalytic pyrolysis of plastic materials, several of which involve the possibility of using solar energy.

[0009] US Patent No. 4,415,339 of the Department of Energy (DOE) teaches a method for producing a substantially hydrocarbon-free product gas (syngas) from a carbonaceous material feed using a solar reactor, the method comprising directing solar energy into the reactor. The solar energy is delivered directly, that is, through a window where the solar rays can pass and heat the material for gasification.

[0010] US 4,582,590 (NASA) discloses a method for pyrolyzing shale, which involves using concentrated solar radiation. The solar radiation passes through a "solar window" and reaches a ceramic honeycomb receiver, which is heated to 350°C.

[0011] WO 2010 / 103520 discloses a solar-powered device for converting sludge by pyrolysis. The device includes a pyrolysis reactor that can be operated by solar energy. This solar energy is concentrated by focusing mirrors and redirected to a receiver located within the pyrolysis reactor. When a sensor detects that the intensity of solar radiation has dropped below a threshold, the reactor shuts down.

[0012] WO 2017 / 055652 (Ministry of Energy) describes a hybrid plant based on the use of solar energy, comprising a molten salt solar receiver configured to heat molten salt using solar energy. The plant comprises cold and hot salt storage tanks, a steam generator, a condenser, and a reactor-salt-biomass exchanger for exchanging heat between streams of salt and biomass.

[0013] CN109207179 discloses a synthesis gas production system via concentrated solar molten salt pyrolysis of carbonaceous materials, such as rice bran, cotton and corn stalk residues, and municipal waste, at temperatures above 800°C, such as 1000°C.

[0014] WO2020 / 150244 (Sabic) discloses the use of renewable energy in paraffin synthesis. In the claimed plant, at least one of the furnaces is an electric furnace, wherein at least 90% of the heating is generated without burning fuel.

[0015] None of the cited patents discloses a method for treating plastic material to produce pyrolysis oil by using solar energy.In addition, in most cases solar energy is used directly, for example by focusing solar radiation directly onto an absorbing surface located inside a reactor.

[0016] Some patent applications disclose the use of molten salt as a heat transfer medium to produce synthesis gas from biomass (such as municipal waste, cotton, corn stalks, and rice bran). Biomass is chemically very different from plastic materials, and the product (synthesis gas) is completely different from pyrolysis oil. Therefore, the required operating conditions (such as temperature) are very different (even exceeding 1000°C). This method is generally not capable of performing the tasks of the present invention: for example, as disclosed in the cited CN109207179, the molten salt used melts at approximately 400°C. In general, to avoid solidification of the salt mixture in the device, it is unsafe to use molten salt near its melting point, which means that this method cannot be used for the pyrolysis of plastics that require temperatures of 400-520°C.

[0017] Pyrolysis of plastic materials is a highly desirable process because it allows the recycling of mixed plastic waste materials by breaking down polymer chains into small organic molecules that can, after appropriate refining processes, be used to synthesize polymers. Most other recycling methods, such as so-called mechanical recycling (i.e., extruding waste plastics together with virgin plastics to create a blend), require the use of very pure plastic waste (i.e., containing only specific polymers, such as expanded polystyrene or linear low-density polyethylene or polyethylene terephthalate). In reality, different polymers are incompatible with one another, and therefore the blending of such polymer mixtures with specific virgin polymers significantly reduces their effectiveness.

[0018] Other recycling methods, such as solvent dissolution and precipitation, can be used to specifically dissolve certain plastic materials, allowing for the precipitation of nearly pure polymers. However, these methods require significant amounts of solvent, and it is also necessary to remove undissolved plastics and purify the solvent from all dissolved and dispersed contaminants (such as short-chain molecules, inorganic additives used as fillers, and so on). Furthermore, these methods can only be used for selected plastics, as dissolving polyolefins, for example, is quite difficult.

[0019] Pyrolysis of plastic materials has the key advantage that it can operate effectively on mixed plastic waste, even in the presence of non-plastic waste materials (such as paper). Moreover, unlike other technologies, it can recycle mixed plastic waste indefinitely, with an infinite loop of making plastic from monomers, using the plastic, collecting its waste after use, and making monomers through pyrolysis of its waste, thus closing the loop. For this reason, this method is often referred to as "closed loop recycling."

[0020] However, pyrolysis is a strong endothermic process and therefore it requires a large amount of thermal energy. In addition, because the required pyrolysis temperature is quite high (>500 ° C), high-quality (that is, high available energy) heat is required. Therefore, only a small amount of energy can be used in this range. Typically, this energy is a gas heater (which burns natural gas and / or the non-condensable gases produced by the pyrolysis process itself) or by direct electric heating via the Joule effect. Electricity has very high available energy content and it is inconvenient to use it by Joule heating. In addition, electricity and gas heating greatly contribute to increasing carbon footprint, because the combustion of hydrocarbons produces a large amount of carbonic anhydride (CO ) and in most countries, electricity is produced by gas, oil or carbon combustion. In addition, due to higher temperatures, it is actually not feasible to use heat pumps to pump heat from lower energy heat sources (such as steam or geothermal energy).

[0021] There is therefore a high risk that the unlimited recycling capability of the pyrolysis ("closed loop recycling") is in fact limited by the fact that large amounts of valuable and / or environmentally unfriendly energy sources have to be used.

[0022] As already reported, some patents disclose the direct use of sunlight, collected and concentrated by focusing mirrors, directly into a receiver located within a reactor chamber to produce syngas. However, sunlight is an intermittent source, and therefore syngas production ceases shortly after sunlight levels decrease. Because these methods require higher temperatures and a longer period of time to stabilize, the use of direct sunlight is a significant limitation to their practical implementation.

[0023] Energy storage components such as batteries or, when using high temperature thermal fluids such as molten salts, larger tanks containing the substance can be used. However, the cost remains high and often requires the use of large amounts of precious materials.

[0024] There has therefore long been a need for a method of producing pyrolysis oil from substantially plastic materials using renewable energy and which can address the intermittency and variability of this energy source while producing pyrolysis oil of consistent quality. Summary of the Invention

[0025] Applicants have unexpectedly discovered a method for producing at least one pyrolysis oil from a substantially plastic material using a variable intensity energy source, comprising the steps of:

[0026] a) heating a heat transfer fluid to a temperature (THTF) comprised between 350° C. and 700° C. by means of a variable intensity energy source;

[0027] b) heating the pyrolysis reactor by means of a heated heat transfer fluid;

[0028] c) feeding the substantially plastic material, optionally already in a molten and / or preheated state, to the pyrolysis reactor;

[0029] d) using the variable intensity energy source, in the substantial absence of oxygen and at a pressure of from atmospheric pressure to 20 bar (a), bringing the material in the pyrolysis reactor to a temperature (TMPR) of from 330° C. to 650° C.;

[0030] e) maintaining the material in the pyrolysis reactor at a temperature (TMPR) of 330° C. to 650° C. for a time sufficient to produce at least one effluent in the pyrolysis reactor in a gaseous state;

[0031] f) keeping the composition of the produced pyrolysis oil substantially constant by dynamically adjusting the pressure in the pyrolysis reactor to values ​​between atmospheric pressure and 20 bar (a) relative to a reference temperature (TREF), the reference temperature being the temperature of the heated heat transfer fluid (THTF) or the temperature of the material in the pyrolysis reactor (TMPR);

[0032] g) partially or completely condensing the effluent in the gaseous state so as to form at least one liquid fluid representing in an amount of at least 10% by mass relative to the mass of the substantially plastic material fed and comprising hydrocarbons having a normal boiling point not lower than 25°C.

[0033] In other words, the present invention consists in defining an interpolation equation for the temperature-pressure relationship, where the pressure is the pyrolysis reactor pressure (more precisely, its set point PMPR) and the temperature is the pyrolysis reactor temperature (more precisely, the reference temperature TREF defined above), which interpolation equation is configured to produce pyrolysis oil of substantially constant composition and quality.

[0034] When compared to methods known in the prior art, the method disclosed and claimed in the present invention has the following advantages:

[0035] - the effectiveness of using intermittent and variable intensity energy sources, which are otherwise generally unsuitable for processes for pyrolyzing plastic materials;

[0036] - Constant quality pyrolysis oil product: even with varying energy intensity and even without thermal storage to keep the heat transfer fluid at a constant temperature, the product quality does not change substantially.

[0037] -Resilience of the method to temperature changes

[0038] Closed-loop recycling: The disclosed method can produce liquid hydrocarbons that, after further processing (e.g., through cracking and / or refining processes), can be used to make polymers. After use, objects made from these polymers can be fed back into the disclosed method. The method can be repeated indefinitely. Thus, the plastic material can be recycled a virtually unlimited number of times.

[0039] - No GHG emissions: The heat required for the pyrolysis process is obtained without directly and / or indirectly producing harmful greenhouse gases (such as carbon dioxide, CO2).

[0040] - Mixed plastic waste and Plasmix preparation: Preferably, the process is fed with mixed plastic waste materials, thus requiring little pre-treatment and no need to feed a single source of material (such as essentially pure polyethylene). Even more preferably, the process is fed with residual plastics after a selection process has selected and extracted a single material (especially when the pollution is low, polymers that can be reused as is, such as polyethylene terephthalate (PET) and low-density polyethylene (LDPE)). This feed is sometimes called "Plasmix" (from a plastic mixture). The essentially plastic material that can be fed to the process may contain minor amounts of non-plastic materials (such as wood, paper, concrete, metal and biomass). Plastics containing inorganic fillers and halogens (such as polyvinyl chloride) can also be fed and processed.

[0041] - No pollution: The process is free from pollution and carbon accumulation, clogging, even when the feed substantially plastic material is rich in high hydrocarbon plastics (such as polystyrene) or oxygen-rich polymers (such as polyethylene terephthalate).

[0042] refer to Figure 1 The present invention also discloses and claims a machine for producing at least one pyrolysis oil from a substantially plastic material, the machine comprising:

[0043] A) a pyrolysis reactor (70) having at least one inlet for feeding a substantially plastic material, an outlet for removing at least one gaseous effluent, and a jacket and / or coil having at least one inlet and one outlet for a molten salt;

[0044] B) a condenser (72) receiving the gaseous effluent from the pyrolysis reactor;

[0045] C) a solar collector and receiver assembly (61, 62), the receiver comprising at least one inlet and one outlet for a molten salt, wherein the solar collector is capable of delivering concentrated solar radiation to the solar receiver, which in turn is configured to heat the molten salt;

[0046] D) a first storage tank ("cold storage tank", 63) fluidly connected to the outlet of the molten salt of the pyrolysis reactor (70) to receive and store the molten salt returned from the pyrolysis reactor (A), and the first storage tank is fluidly connected to the inlet of the solar receiver (62);

[0047] E) a second storage tank ("hot storage tank", 64) fluidly connected to the outlet of the solar receiver (62) for receiving and storing molten salt returned from the solar collector and receiver (SCA1), and the second storage tank is fluidly connected to the molten salt inlet of the pyrolysis reactor (70);

[0048] F) a controller (23) which, via a pressure manager (22), adjusts the pressure set point of the pyrolysis reactor (24) relative to a reference temperature TREF, which is the temperature THTF (21A) of the molten salt from the second tank ("hot tank", C2) or the temperature TMPR (21B) of the material in the first pyrolysis reactor (70).

[0049] definition

[0050] In the description of the present invention, unless otherwise specified, range values ​​(eg, ranges of pressure, temperature, amount, etc.) are regarded as including the endpoint values.

[0051] In the description of the present invention, unless otherwise specified, percentages are by weight (ie, by mass). Unless otherwise specified, the symbol "%" means percentage by weight (mass).

[0052] In the description of the present invention, the term "comprising" also includes its meanings of "consisting of" and "consisting essentially of" as specific limitations.

[0053] In the description of the present invention, the term "consisting essentially of" means that the composition or formulation (1) necessarily includes the listed ingredients and (2) is open to unlisted ingredients that do not materially affect the basic and novel properties of the composition.

[0054] In the description of the present invention, unless otherwise specified, the action of maintaining a parameter (such as pressure) within an indicated range means actively performing operations to make this parameter fall within the range, for example by checking that a measured value falls within the indicated range and / or by adjusting the parameter via a feedback adjustment system in which the value of this parameter is set within the indicated range.

[0055] In the description of the present invention, a hydrocarbon having a normal boiling point of not less than 25° C. means that this hydrocarbon independently has a normal boiling point as defined by IUPAC of at least 25° C. (meaning equal to or greater than 25° C.).

[0056] In the description of the present invention, the action of completely or partially condensing the gases leaving the pyrolysis reactor so as to form at least one liquid comprising hydrocarbons having a normal boiling point of not less than 25°C does not exclude that this liquid may also contain hydrocarbons having a boiling point below 25°C, and non-hydrocarbon compounds.

[0057] In the description of the present invention, variable intensity energy sources, or equivalently intermittent energy sources, means energy sources that due to their nature are not able to deliver constant power, such as, for example, solar energy, wind energy, tidal energy, etc.

[0058] In the present description, a substantially plastic material means a composition of one or more plastics optionally containing up to 30 wt% of non-plastic materials, based on the weight of the substantially plastic material.

[0059] In the description of the present invention, plastic materials mean general polymeric materials that may contain other substances to improve performance and / or reduce cost, as defined by IUPAC (Pure Appl. Chem. Vol. 84n. 2, pp 377-410, 2012).

[0060] In the present description, "pyrolysis vapor" means the gaseous phase produced during the pyrolysis of a substantially plastic material, such as the gaseous effluent of a pyrolysis reactor. The effluent contains pyrolysis products as well as compounds that are gaseous under the pressure and temperature conditions of pyrolysis and that are already present in the substantially plastic material undergoing pyrolysis or that have been added or are already present in the pyrolysis reactor (e.g., in an inert atmosphere), such as nitrogen, water, or low-boiling plasticizers. The hydrocarbon content of the pyrolysis vapor is typically greater than 50 wt%.

[0061] In the description of the present invention, "pyrolysis oil" means a liquid formed by partially or completely condensing pyrolysis vapor, the liquid containing hydrocarbons having a normal boiling point of not less than 25° C. The content of hydrocarbons in the pyrolysis oil is generally greater than 50 wt%.

[0062] In the description of the present invention, the pyrolysis residue or char means the product in the pyrolysis reactor in a liquid, solid, or semi-liquid state.

[0063] In the description of the present invention, unless otherwise specified, the substantial absence of oxygen means that the oxygen (to be understood as molecular oxygen) in the pyrolysis vapor is less than 2% by weight, preferably less than 0.8% by weight, and even more preferably between 20 ppm and 4000 ppm by weight relative to the total weight of the composition of the vapor.

[0064] In the present description, a heat transfer fluid is a solid, liquid, gaseous, or multiphase fluid used to transfer heat from one system to another, particularly from a heat source to another heat demand (heat load). Preferably, the heat transfer fluid is a fluid specifically manufactured for the purpose of transferring heat and is stable (i.e., does not degrade rapidly) under the conditions of the process employed.

[0065] In the present description, molten salt means a salt that is solid at ambient temperature and ambient pressure, i.e., 25° C. and 1 bar, but enters the liquid phase due to high temperature. The molten salt may consist of a single component (e.g., sodium nitrate alone) or a mixture of salts (e.g., a mixture of sodium nitrate and potassium nitrate).

[0066] In the description of the present invention, unless otherwise specified, for a parameter value equal to at most a certain value X, it means that the parameter is equal to X or less than X; and for a parameter value equal to at least a certain value X, it means that the parameter is equal to X or greater than X.

[0067] In the description of the present invention, unless otherwise specified, the yield in the output of a product means the weight percentage of the product relative to the total of the obtained products.

[0068] "C5-C12 wax fraction" means the sum of the masses of compounds having 5 to 12 carbon atoms (inclusive) in the wax relative to the total mass of the wax product.

[0069] The “C5-C12 light oil fraction” means the sum of the masses of compounds having 5 to 12 carbon atoms (inclusive) in the light oil relative to the total mass of the wax product.

[0070] "C5-C12 yield" means "C5-C12 light oil fraction" multiplied by "light oil fraction" plus "C5-C12 wax fraction" multiplied by "wax fraction".

[0071] Thus, the "C5-C12 yield" is the ratio of the mass of compounds having 5 to 12 carbon atoms in the pyrolysis oil product to the mass of substantially plastic material fed to the pyrolysis reactor.

[0072] "Hydrocarbon" means a compound composed of carbon and hydrogen atoms. Thus, compounds having heteroatoms (such as N, S, O) are excluded.

[0073] "C5-C12 hydrocarbon wax fraction" means the sum of the mass of hydrocarbons having 5 to 12 carbon atoms (inclusive) in the wax relative to the total mass of the wax product.

[0074] The “C5-C12 hydrocarbon light oil fraction” means the sum of the mass of hydrocarbons having 5 to 12 carbon atoms (both inclusive) in the light oil relative to the total mass of the wax product.

[0075] "C5-C12 hydrocarbon yield" (or equivalently, "C5-C12 hc yield") means "C5-C12 hydrocarbon light oil fraction" multiplied by "light oil fraction" plus "C5-C12 hydrocarbon wax fraction" multiplied by "wax fraction." Thus, the "C5-C12 hydrocarbon yield" is the ratio of the mass of hydrocarbons having 5 to 12 carbon atoms in the pyrolysis oil product to the mass of the substantially plastic material fed to the pyrolysis reactor.

[0076] "Ihc fraction" means the ratio of the C5-C12 hydrocarbon yield to the C5-C12 yield. Thus, the "Ihc fraction" is the fraction (percentage) of hydrocarbons in the C5-C12 cut.

[0077] Unless otherwise specified, in this document "part" and "parts" mean part by weight and parts by weight, respectively. Weight means mass, ie kg in SI units.

[0078] Unless otherwise specified, in this document the combination of an individual range from one list with another individual range from a second range list and relating to different features shall be considered disclosed in this application even in the absence of an explicit indication of this combination. BRIEF DESCRIPTION OF THE DRAWINGS

[0079] Figure 1 A process flow and associated machinery are shown illustrating an embodiment of the present invention, which features two heat transfer fluid storage tanks, a pyrolysis reactor, a solar collector assembly, and a pressure regulation system for the pyrolysis reactor.

[0080] Figure 2 The method flow and related machine equipment of the embodiment of the present invention are shown, which are characterized by Figure 1 The same elements of the reactor plus some optional equipment: preheater, second reactor, char feeder and coker.

[0081] Figure 3 A method flow diagram and related machinery are shown illustrating the process for condensing the pyrolysis vapor effluent of a pyrolysis reactor, which is characterized by the use of three condensers in series, a first condenser cooled by a heat transfer fluid, and a third condenser as a submerged condenser.

[0082] Figure 4 A method flow diagram and related machinery are shown illustrating a process for feeding a heat transfer fluid to multiple devices (preheater, pyrolysis reactor, second pyrolysis reactor) through a weir in a semi-series manner.

[0083] Figure 5The diagram shows three different interpolation equations for the temperature-pressure relationship. From top to bottom, the interpolation equations shown are linear interpolation, monotonic non-increasing piecewise constant function, and generalized logistic function. DETAILED DESCRIPTION

[0084] An embodiment of the present invention is shown in Figure 1 The process includes:

[0085] - a pyrolysis reactor (70);

[0086] - a pyrolysis vapor accumulation valve (81) which regulates the pressure in the reactor (70) by the accumulation of pyrolysis vapors leaving the reactor;

[0087] - a condenser (72) which condenses the pyrolysis vapors;

[0088] - a separator (73) which separates the gaseous phase (non-condensed) from the liquid phase;

[0089] - Solar collector (61) and receiver (62);

[0090] - a "cold" storage tank (63) for the heat transfer fluid;

[0091] - a "hot" storage tank (64) for a heat-transfer fluid;

[0092] - heat transfer fluid pumps (65), (66) that deliver the heat transfer fluid to the heating system (solar receiver) and the pyrolysis reactor (70);

[0093] -Bypass (B1) and (B2) are optional;

[0094] - a temperature transmitter (21) which reads the temperature of the heat transfer fluid;

[0095] - a pressure transmitter (24) which reads the pressure of the pyrolysis reactor (70);

[0096] - a pressure controller (23) that regulates the pressure of the pyrolysis reactor (70) by adjusting the opening of the pyrolysis vapor accumulation valve (81);

[0097] - a pressure manager (22) which sets the pressure set point PMPR of the pyrolysis reactor (70) relative to the temperature TREF being the temperature THTF of the heat transfer fluid (21A) or the temperature TMPR of the material in the (first) pyrolysis reactor (70).

[0098] In connection with the invention, the invention relates to a machine for producing at least one pyrolysis oil from essentially plastic material:

[0099] - in the pyrolysis reactor (70), the outlet for removing at least one gaseous effluent is fluidly connected to a condenser (72) which receives the gaseous effluent of the pyrolysis reactor [(A)-(B) connection];

[0100] - in the pyrolysis reactor (70), in a jacket and / or coil having at least one inlet and one outlet for molten salt, the at least one inlet being fluidly connected to the second tank ("hot tank", 64) which receives and stores the molten salt returned from the solar collectors and receivers [(A)-(E) connections];

[0101] - in the pyrolysis reactor (70), in a jacket and / or coil having at least one inlet and one outlet for the molten salt, the at least one outlet being fluidically connected to the first tank ("cold tank", 63) which receives and stores the molten salt returning from the pyrolysis reactor (A) [(A)-(D) connection];

[0102] - In the solar collector and receiver assembly (61, 62), the inlet for the molten salt is fluidically connected to a first tank ("cold tank", 63) which receives and stores the molten salt returning from the pyrolysis reactor [(C)-(D) connection];

[0103] - In the solar collector and receiver assembly (61, 62), the outlet of the molten salt is fluidly connected to a second storage tank ("hot storage tank", 64), which receives and stores the molten salt returned from the solar collector and receiver [(C)-(E) connection];

[0104] - a pressure controller (23) which regulates the pressure of the pyrolysis reactor (24) relative to a reference temperature TREF electronically connected to a temperature sensor of the temperature THTF (21A) of the molten salt coming from the second tank ("hot tank", C2) or to a temperature sensor of the temperature TMPR 21B of the material in the first pyrolysis reactor (70) [(A)-(F) connections].

[0105] In the context of the present invention, a fluid connection may include a device sandwiched or positioned in any way between, such as, for example, a pump and a valve.

[0106] In the context of the present invention, an electronic connection includes any non-mechanical and non-thermal means of transmitting information, such as a flow of electrons (electrical current) or a flow of photons (light transmission, such as through optical fiber) or electromagnetic waves (e.g., WiFi transmission).

[0107] Basically the plastic material (at 51) is fed to the first pyrolysis reactor (70) which is heated by the heat transfer fluid (33) from the hot storage tank (64). The heat transfer fluid from the first pyrolysis reactor (thus at a lower temperature) reaches the cold storage tank (63).

[0108] The solid or semi-solid residue (eg, char) is recovered (at 53).

[0109] In some embodiments, a portion of the liquid contained in the first pyrolysis reactor (70) may also be recovered from (53).

[0110] The outflow from the second reactor (71) is cooled and condensed by means of a condenser (72). Uncondensed gases are recovered at (55). The condensate forms pyrolysis oil which is collected in a storage tank (73) and recovered (at 56). The storage tank (73) may optionally be integrated into the condenser (72).

[0111] Optional bypasses (B1) and (B2) can be used to refill the tanks one after the other without passing through the heating system and the load (for maintenance and / or to decouple the flow rate from the heat load).

[0112] The solar collector (61) and receiver (62) heat the heat transfer fluid (31) from the cold storage tank (63). From the solar receiver (62), the heat transfer fluid reaches the hot storage tank (64).

[0113] The temperature transmitter (21) reads the temperature of the heat transfer fluid. According to another embodiment, this temperature transmitter can directly read the temperature of the non-gas phase inside the pyrolysis reactor (70).

[0114] The pressure transmitter (24) reads the pressure of the pyrolysis gas. This transmitter can be placed inside the reactor or any other location where the pressure is substantially the same.

[0115] exist Figure 1 In the embodiment, the pressure transmitter (24) is located in the connection that allows the pyrolysis vapor (52) generated in the pyrolysis reactor (70) to reach the lamination valve (81). In this position, the pressure reading can be even more reliable and accurate than in the position inside the reactor. In fact, inside the reactor, boiling conditions can exist and foaming can occur due to sudden pressure release. If the sensor is located inside the reactor, it is therefore more likely to be contaminated.

[0116] The pressure transmitter (24) is connected to a pressure controller (23) which regulates the opening of the valve (81) to achieve the pressure set point via the pressure regulator (22).

[0117] The pressure manager (22) sets a pressure set point relative to the temperature measured by the transmitter (21).

[0118] Some embodiments of possible different relationships between the temperature and the pressure set point are given below.

[0119] Preferably, the substantially plastic material comprises a composition of different plastics. More preferably, the composition of different plastics comprises at least a polymer with a high H / C ratio (such as polyethylene, polypropylene, polyamide, polymethyl methacrylate), and a polymer with a low H / C ratio (such as polystyrene, polycarbonate, polyethylene terephthalate).

[0120] Alternatively or in combination, the different plastic compositions include high carbon index polymers (such as polyethylene (including LDPE, LLDPE, HDPE), polypropylene, polystyrene, elastomers) and low carbon index polymers (such as polyamide, polymethyl methacrylate, polyethylene terephthalate, polyvinyl chloride and cellulose).

[0121] Preferably, the substantially plastic material is characterized by an H / C ratio (H / C index) equal to at least 70, preferably ranging from 80 to 98, even more preferably ranging from 85 to 96.

[0122] Preferably, the substantially plastic material is characterized by a carbon index equal to at least 55, preferably ranging from 65 to 95, even more preferably ranging from 75 to 90.

[0123] The H / C index is proportional to the ratio of the total mass of hydrogen atoms to the total mass of carbon atoms present in the substantially plastic material and is calculated using the following formula:

[0124]

[0125] The carbon index is proportional to the ratio of the total mass of carbon atoms to the total mass of all atoms present in substantially the plastic material and is calculated using the following formula:

[0126]

[0127] The "total atomic weight" corresponds to the weight of the plastic material.

[0128] Preferably, the substantially plastic material contains at least one non-plastic material in an amount ranging from 0.01% to 10% by weight, more preferably in an amount ranging from 0.05% to 7.5%, even more preferably in an amount ranging from 0.2% to 5%, relative to the weight of the substantially plastic material. The non-plastic material preferably comprises at least one of the following materials: paper, cardboard, wood, compost (as defined by IUPAC in "Terminology for biorelated polymers and applications (IUPAC Recommendations 2012)", Pure Appl. Chem., Vol 84, No 2, pp 377-410, 2012, DOI 10.1351 / PAC-REC-10-12-04), metallic materials (such as aluminum and iron), and / or inert materials.

[0129] Optionally, the substantially plastic material contains inorganic fillers such as, for example, silica, titanium oxide, talc, coke, graphite, carbon black, calcium carbonate.

[0130] Optionally, the substantially plastic material contains brominated and chlorinated additives for rendering the plastic material fireproof or in any case imparting flame propagation retardation properties. Examples of such additives are hexabromocyclododecane, decabromodiphenoxy, polybrominated diphenyl ethers, and bromine-containing polymers such as brominated styrene-butadiene copolymers or brominated polystyrene.

[0131] Optionally, the substantially plastic material contains non-halogenated additives for rendering the plastic material fireproof or in any case imparting flame propagation retardation properties, such as phosphorus compounds and nitrogen compounds.

[0132] Preferably, the substantially plastic material is also recyclable.

[0133] Preferably, the substantially plastic material further comprises a halogenated component in an amount ranging from 0.01 wt% to 10 wt% relative to the weight of the substantially plastic material.

[0134] Preferably, the substantially plastic material is obtained from a plastic material sorting process. More preferably, the substantially plastic material is a substantially plastic residue material, i.e., the substantially plastic fraction remaining after recycling some plastics or after selectively extracting some plastics from the substantially plastic material fed to a selection process. Selective extraction consists of extracting a substantially homogeneous material of certain plastics (i.e., as a single plastic). Typically, in a selection process (sorting), a stream of substantially pure plastic (i.e., as a single plastic) of polyethylene, polypropylene, and polyethylene terephthalate components can be extracted. Therefore, in this preferred embodiment, the substantially plastic residue material is the material resulting from the extraction of the substantially pure plastic. This fraction is known in Italy by the terms "Plas Mix" or "Plasmix," defined as "a collection of heterogeneous plastics contained in post-consumer packaging and not recovered as individual polymers" (paragraph 1 of the draft bill of the House of Representatives, n. 4502, dated 18 May 2017).

[0135] Another embodiment of the present invention is shown in Figure 2 The process includes Figure 1 Same components as above and in addition:

[0136] - a preheater (74) of essentially plastic material;

[0137] - a second pyrolysis reactor (71);

[0138] - a char feeder (75), which is an element capable of moving the liquid, solid or semi-solid material contained in the pyrolysis reactor to the coker (76);

[0139] - a coker (76), which is an element capable of subjecting the liquid, solid and semi-solid materials coming from the pyrolysis reactor to high-temperature thermal treatment;

[0140] - Coke collector (77).

[0141] The above elements are optional and may be present individually or in any possible combination.

[0142] In the already crowded Figure 2 In the example, the reference temperature TREF is the temperature of the heat transfer fluid THTF; however, in Figure 2 The same embodiments represented in but wherein TREF is the temperature of the material in the first pyrolysis reactor are also part of the present invention.

[0143] In embodiments where there is a second pyrolysis reactor, the pyrolysis reactor (70) is referred to as the first pyrolysis reactor to avoid confusion. In any case, unless otherwise stated (e.g., using "second pyrolysis reactor"), the pyrolysis reactor means the (first) pyrolysis reactor (70).

[0144] Specifically, according to Figure 2 In one embodiment described, the plastic material is preheated in a preheater (74) and then fed into the pyrolysis reactor (70). Figure 2 It is shown that the heat-carrying fluid is fed continuously to the pyrolysis reactor and the preheater, preferably the fluid is sent to the pyrolysis reactor and then to the preheater.

[0145] According to Figure 2 In another embodiment described in , the liquid, solid or semi-solid material of the pyrolysis reactor is discharged through a char feeder device (75).

[0146] According to Figure 2 In another embodiment described in , in the second pyrolysis reactor (71), the cracked gas from the first pyrolysis reactor (70) is further heated to a higher temperature by the heat transfer fluid (37) from the hot storage tank (64). In the second reactor (71), the pyrolysis gas is thus further pyrolyzed.

[0147] The second reactor (71) may contain at least one catalyst, preferably a solid catalyst, or no catalyst. When no catalyst is used, in this second pyrolysis reactor, the gaseous effluent from the first pyrolysis reactor is heated to a temperature (TMSR) that is higher than the temperature of the material in the first pyrolysis reactor (temperature TMPR). When a catalyst is used, the gaseous effluent from the first pyrolysis reactor is optionally heated or cooled to a temperature (TMSR) that is different from the temperature (TMPR) of the material in the first pyrolysis reactor and then passed through the catalyst. Preferably, when heating the gaseous effluent from the first pyrolysis reactor, the temperature difference between the temperature (TMSR) of the gaseous effluent after heating and the temperature (TMPR) of the material in the first pyrolysis reactor is at least 10°C, preferably 30°C to 300°C, even more preferably 60°C to 250°C. According to one embodiment, when the gaseous effluent from the first pyrolysis reactor is cooled and a catalyst is used, the absolute value of the temperature difference between the gaseous effluent after cooling (TMSR) and the temperature of the material in the first pyrolysis reactor (TMPR) is between 10°C and 250°C, preferably between 30°C and 150°C.

[0148] Thus, according to one embodiment of the present invention, in the process for producing at least one pyrolysis oil from a substantially plastic material, the gaseous effluent of the pyrolysis reactor, before condensation in step (g), is passed to a second pyrolysis reactor, wherein, if no catalyst is used, the gaseous stream is heated to a temperature (TMSR) higher than the temperature (TMPR) of the substantially plastic material of step (e); or, if a catalyst is used, wherein the gaseous effluent of the pyrolysis reactor, before condensation in step (g), is optionally heated or cooled to a temperature (TMSR) higher or lower, respectively, than the temperature (TMPR) of the substantially plastic material of step (e), and then passed through the catalyst. Preferably, when the gaseous stream is heated to a temperature higher than the temperature (TMPR), the gaseous stream reaches a temperature of at least 10° C. higher than the temperature of the substantially plastic material of step e), preferably from 30° C. to 300° C., even more preferably from 60° C. to 250° C.

[0149] According to another embodiment, the second pyrolysis reactor is operated at a temperature higher than the temperature of the first pyrolysis reactor if no catalyst is used in the second pyrolysis reactor, or about the same temperature or higher if a catalyst is used, with the additional proviso that this temperature is between 400°C and 650°C, preferably between 440°C and 550°C, even more preferably between 460°C and 530°C.

[0150] The residence time of the pyrolysis vapor in the second pyrolysis reactor, calculated divided by the volume occupied by the vapor and the volume flow rate in the reactor, is at least 10 seconds, preferably 30 seconds to 6 minutes, even more preferably 1 minute to 4 minutes.

[0151] Preferably, the second pyrolysis reactor is catalytic. More preferably, the gaseous effluent is in relative motion with respect to the solid catalyst in contact with the gaseous effluent, and the relative motion is at a speed of at least 0.5 m / s, more preferably 2 to 50 m / s.

[0152] All pyrolysis catalysts known in the art to which the present invention pertains can be used, including in particular zeolites.

[0153] Thus, according to one embodiment of the present invention, in the method for producing at least one pyrolysis oil from a substantially plastic material, the second reactor contains a catalyst, wherein the gaseous effluent of the pyrolysis reactor is contacted with the catalyst.

[0154] The second pyrolysis reactor can be operated at the same pressure as the first pyrolysis reactor (70) or at a lower pressure; preferably, the second pyrolysis reactor is operated at a pressure comprised between atmospheric pressure reduced by 10,000 Pa and the pressure of the first pyrolysis reactor. Even more preferably, the second pyrolysis reactor is operated at a pressure comprised between the pressure of the first pyrolysis reactor and the pressure of the first pyrolysis reactor reduced by 10,000 Pa.

[0155] A separator (77) which can be integrated into the coker unit allows the gas phase (53E) to be recycled back into the process (e.g. in Figure 2 ) in the first pyrolysis reactor described herein, while the non-gas phase is collected in a stream (53D).

[0156] The char feeder device (75) can be a pumping device that moves solid, semi-solid, or liquid material from the pyrolysis reactor to the coker device while allowing for physical separation between the two devices. An example of such a device is a gear pump. Alternatively, the char feeder device (75) can be a valve, such as a rotary valve, a gate valve, or a butterfly valve.

[0157] Advantageously, according to this embodiment, if the heat transfer fluid is fed in a sequential arrangement, the high temperature heat fluid (37) from the heat storage tank is preferably delivered first to the coker unit (76) and then to the pyrolysis reactor (70). Advantageously, the char feeder unit (75) can be heated by the heat transfer fluid leaving the heating jacket of the pyrolysis reactor (70).

[0158] In the coker (76), the material is heated to a temperature of 500°C to 1200°C, preferably 600°C to 1000°C, even more preferably 700°C to 900°C for a period of at least 5 minutes, preferably 15 minutes to 180 minutes, even more preferably 30 minutes to 120 minutes.

[0159] Thus, according to one embodiment of the present invention, the solid, semi-solid or liquid material in the pyrolysis reactor is withdrawn and heated to a temperature of 500 to 1200°C, preferably 600 to 1000°C, even more preferably 700 to 900°C for a period of at least 5 minutes, preferably 15 to 180 minutes, even more preferably 30 to 120 minutes.

[0160] As a coker, any device that can perform this operation is suitable. Preferably, the coker is a device comprising a rotating screw. Even more preferably, the rotating screw is horizontal or inclined at an angle of at most 30° relative to the horizontal axis.

[0161] The coker may be heated by a heat transfer fluid, by electrical resistance (Joule effect), or a combination thereof.

[0162] According to another embodiment of the present invention, the condensation of the pyrolysis gases leaving the pyrolysis reactor is divided among a plurality of units, such as two or more units, or three or more units. Figure 3One embodiment is shown, which is divided into three units (72A), (72B), and (72C). In more detail, the pyrolysis gas (54) leaving the pyrolysis reactor passes through a first condenser (72A) at a "high temperature" and a first separator (73A), which separates a first condensed liquid (56A) from a first non-condensed vapor (55A). The first non-condensed vapor (55A) then passes through a second condenser (72B) at a lower temperature and a second separator (73B), which separates a second condensed liquid (56B) from a second non-condensed vapor (55B). The second non-condensed vapor (55B) then passes through a third condenser (72C) at an even lower temperature than the second condenser and a third separator (73C), which separates a third condensed liquid (56C) from a third non-condensed vapor (55C).

[0163] Therefore, according to one embodiment of the present invention, the condensation of step g) is performed in a plurality of condensation units connected in series.

[0164] Advantageously, according to this embodiment, the cooling of the first condenser (72A) is carried out by means of the high-temperature thermal fluid (33E) that has already been used to heat the pyrolysis reactor, before entering the cold storage tank (63). In this way, there is a heat recovery that allows reducing the overall heat load for condensing the pyrolysis oil and, at the same time, by heating the high-temperature thermal fluid, it reduces the required heat load for the solar collectors and receivers.

[0165] Figure 3 Two additional modes for controlling pressure according to the present invention are also shown.

[0166] Specifically, the pressure controller (23) that changes the pressure of the pyrolysis reactor (70) may adjust the opening of the valve on the non-condensable gas stream (55). Alternatively or in combination (the latter being Figure 3 (configuration shown), when using a submerged condenser, in order to vary the pressure of the pyrolysis reactor (70), the pressure controller (23) can adjust the submergence of the condenser (72C), for example by regulating the opening of a valve on the condensed liquid from this condenser (72C). In fact, in a submerged condenser, the condensation power is essentially proportional to (or at least a monotonic function of) the area of ​​the condenser not covered by condensate. This is due to the fact that the heat transfer coefficient is much higher for the boiling / condensation ("latent") phenomenon than for heat conduction alone. With a submerged condenser, its power is thus significantly reduced. Since the density of the liquid phase is several orders of magnitude higher than that of the vapor phase, condensation reduces the pressure of the system; therefore, the pressure can be regulated by acting on the condensation power.

[0167] exist Figure 3In the embodiment, pressure control is performed by adjusting the condensing power (valve 81C) and adjusting the flow of non-condensable effluent (valve 81B).

[0168] Therefore, according to one embodiment of the invention, regulating the pressure in the pyrolysis reactor is performed by adjusting the pressure drop of the effluent of the pyrolysis reactor in the gaseous state before the condensation of step g).

[0169] According to another embodiment of the invention, regulating the pressure drop over the gaseous effluent is performed by means of a throttling device, preferably a valve.

[0170] When using multiple devices to control pressure, such as Figure 3 As shown, a so-called split range control mode can advantageously be used.

[0171] According to the split range control mode, the operation is performed on a single device at a time. The device is selected based on the controller's "operation point" (OP). For example, in Figure 3 In the case of , for OP values ​​between 0 and 50, valve 81B remains at 0 (valve remains closed) while the valve (valve 81C) that regulates the level of the submerged condenser is changed. In this way, the pressure is varied by varying the power of the condenser. For OP values ​​between 50 and 100, valve (81C) remains fully open, gradually varying the opening of valve (81B). In this way, the pressure of the pyrolysis reactor is regulated by varying the power of the condenser, but if the pressure remains above the desired set point, the condenser remains at maximum power and the pressure is regulated by varying the opening of valve 81B on the residual gas (non-condensable stream). Under relatively static conditions, the pyrolysis process generally produces some non-condensable gases, so if adjustments are made in this mode, the OP value is maintained between 50 and 100, the condenser is operated at maximum power, while regulating the opening of the valve on the residual gas.

[0172] All other auxiliary and miscellaneous devices and parts connecting these devices (e.g., connecting pipes) can be heated using the same heat transfer fluid used to heat the devices disclosed in the present invention (pyrolysis reactor, coker, etc.).

[0173] Preferably, the distribution of the heat transfer fluid to the devices can be performed in series, in parallel or in semi-series.

[0174] When connected in series, preferably the heat transfer fluid from the hot storage tank (64) is fed first to the device requiring higher temperature (such as the coker) and the pyrolysis reactor, and then to other devices, such as the preheater (74) or the char feeder device (75). More preferably, the order is: coker (76) (if present and if heated by the heat transfer fluid), the second pyrolysis reactor (71), the first pyrolysis reactor (70), then (if present) the preheater (74) and then (if present) the char feeder device (75). According to other embodiments, if the condensation is divided into two or more steps and the cooling fluid in the first condenser is the heat transfer fluid, such as Figure 3 Description, the series also includes the first condenser, and preferably the last element in the sequence is the first condenser.

[0175] Semi-series is a combination of series and parallel that allows to obtain the advantages of both series and parallel modes.

[0176] An embodiment of a semi-series configuration is described in Figure 4 middle.

[0177] Figure 4 A weir device (78) is shown which receives heat transfer fluid from the hot storage tank (64) and delivers this fluid to the second pyrolysis reactor (71), the first pyrolysis reactor (70) and the preheater (74), and finally releases this fluid to the cold storage tank (63). According to this embodiment, the weir device comprises a first chamber, into which the oil from the hot storage tank is sent. In the first chamber is located a first pump (66B), which delivers the heat transfer fluid to the first pyrolysis reactor (70). The heat transfer fluid leaving the first pyrolysis reactor enters the same chamber. The weir, which can be, for example, a Bazin weir, ensures that there is sufficient pressure head (net positive suction pressure head) to avoid cavitation when pumping the heat transfer fluid into the second pyrolysis reactor (71), as well as entrainment of the gas phase. This weir also forms a containment wall of the first chamber, so that the fluid inside the chamber is recirculated. This ensures uniformity of the fluid temperature inside the chamber and high resilience to instabilities in the flow rate of the fluid input from the hot storage tank.

[0178] Excess heat transfer fluid overflows the weir, thereby entering the subsequent chamber. Similar to the first chamber, another pump (66B) is positioned in the subsequent chamber, which delivers the heat transfer fluid to the first pyrolysis reactor (70) and collects its return. Similarly, another weir ensures that the pump (66B) that delivers the fluid to the reactor has sufficient NPSH and is free of entrained gas. Excess heat transfer fluid overflows the weir, thereby entering the subsequent chamber. Similar to the second chamber, another pump (66B) is positioned in the third chamber, which delivers the heat transfer fluid to the preheater (74) and collects its return. Similarly, another weir ensures that the pump (66B) that delivers the fluid to the pre-reactor has sufficient NPSH and is free of entrained gas. Finally, the last chamber includes another pump that delivers the heat transfer fluid to the cold storage tank (63). The starting and stopping of this pump can be automatically handled by a liquid level switch, so that the pump is only started when the liquid level in the last chamber is above a given height.

[0179] Unlike a serial configuration, the weir device (78) allows different flow rates of heat transfer fluid to be delivered to each device. Unlike a parallel configuration, where all devices share the same source (heat reservoir), the weir device allows heat transfer fluid to be delivered at a higher temperature to devices that require a higher temperature and a higher correlation (i.e., if there is a constant temperature of the heat transfer fluid compared to the temperature of the successive chambers).

[0180] Thus, the weir arrangement allows for greater flexibility and effectiveness if compared to a standard parallel or series arrangement.

[0181] In another embodiment, the weir device can be located within the hot storage tank itself, eliminating the need for a pump to deliver the heat transfer fluid to the weir device. In another embodiment, the cold and hot storage tanks can be located within the solar field, while the pyrolysis equipment can be located some distance away from the solar field. In this case, a buffer tank is required to prevent any problems with the delivery of the heat transfer fluid from causing the pyrolysis process to fail.

[0182] In this case, the weir arrangement may also serve as a buffer tank.

[0183] It will be appreciated that there are many different other customizations of the weir device, for example allowing more chambers for managing more devices to be heated by the heat carrier fluid.

[0184] Advantageously, all devices receiving heat transfer fluid are placed at different height levels so that a minimum number of heat transfer pumps is required.

[0185] More precisely, according to this embodiment, the first device receiving the heat transfer fluid from the pump (66) is located at a maximum height level, and the device receiving the heat transfer fluid leaving the first device is located at a lower height level, so that the fluid can flow into the device by gravity. By doing this, no additional pump is required.

[0186] This is advantageous because any moving parts on the fluid at higher temperatures, which may also exhibit high melting temperatures, are particularly fragile and may require special measures for proper startup and maintenance if they fail. Furthermore, in this way, the pressure of the heat transfer fluid in the device can be atmospheric pressure, simplifying the design and reducing the cost of the device. Last but not least, since the heat jacket is not under pressure, accidental rupture of the heat jacket is much safer because spillage due to rupture is reduced.

[0187] According to a preferred embodiment, the hot heat transfer fluid storage tank and the cold heat transfer fluid storage tank are both located at ground level.

[0188] The cold and hot storage tanks may optionally contain some mixing means, such as an internal recirculation pump, or an agitator, for example an anchor agitator, a turbine agitator, or a pitched blade impeller. Such mixing means improves the homogenization of the temperature in the storage tanks and may be particularly useful, especially at startup.

[0189] However, even in the absence of such mixing means, the flow of the heat transfer fluid from the inlet to the outlet and natural convection induce a certain degree of internal recirculation and mixing in the tank.

[0190] The preheater (74) may be substantially any device in which the plastic material may be heated and preferably partially or completely melted.

[0191] Examples of such devices are single-screw extruders, twin-screw extruders, or more generally, screw devices capable of conveying plastic material and having a jacket or equivalent means in which a heat-carrying fluid can flow.

[0192] Optionally, a heat transfer fluid also flows inside the screw, thereby improving the efficiency of the device.

[0193] Preferably, the device can be almost airtight so that the gas in the first pyrolysis reactor (70) does not leave the pyrolysis reactor (70). This result is achieved by using the same plastic melt flowing between the screw and the barrel as a method of achieving airtightness.

[0194] The preheating device can be equipped with a degassing device for evacuating water vapor and any other gases produced, in particular hydrogen chloride (HCl). For this purpose, advantageously, in addition to the substantially plastic material, the preheating device is also fed with an additive capable of promoting the release of hydrochloric acid or its salt formation. This additive is preferably a compound of an element of Group IA or Group IIA. More preferably, it is an oxide, hydroxide, carbonate, silicate, or aluminosilicate of Group IA or Group IIA. Even more preferably, it is calcium oxide, calcium hydroxide, calcium carbonate, sodium oxide, sodium hydroxide, sodium carbonate, potassium oxide, potassium hydroxide, potassium carbonate, or sodium aluminosilicate.

[0195] The preheating temperature may be 120°C to 360°C, preferably 150°C to 260°C, more preferably 170°C to 230°C, even more preferably 180°C to 210°C, and the plastic feed is optionally partially or completely melted before feeding into the pyrolysis reactor.

[0196] The residence time in the preheating device is preferably less than 10 minutes, more preferably less than 2 minutes, in particular less than one minute.

[0197] The first pyrolysis reactor (70) can be any reactor capable of receiving a substantially plastic feed and subjecting it to pyrolysis conditions (temperature and pressure).

[0198] The first pyrolysis reactor for pyrolyzing substantially plastic material can be operated in batch mode, continuous mode, and semi-continuous mode. In the latter mode, substantially plastic material is continuously loaded, the generated steam is continuously extracted, but any solid residue is discontinuously removed from the pyrolysis reactor.

[0199] When the amount of solid residue inside the reactor rises above a certain threshold value, or at predetermined time intervals, for example at a frequency ranging from 2 to 10 days, the solids contained in the reactor are removed.

[0200] Preferably, the reactor is operated in continuous or semi-continuous mode, more preferably in semi-continuous mode.

[0201] The pyrolysis process of the present invention is not limited to a particular reactor type.

[0202] In particular, horizontal or vertical, stirred or non-stirred reactors, kiln reactors, or screw reactors can be used. Fluidized bed reactors are not preferred.

[0203] Among stirred reactors, continuous stirred reactors (CSTRs) and multi-zone reactors can be used. Plug flow reactors (PFRs) can also be used, preferably with stirring to facilitate heat transfer.

[0204] In a continuous stirred reactor (CSTR), a completely filled reactor (meaning that there is essentially no gas phase above the processed plastic melt and reaction products (such as char)) and a reactor in which the gas phase is separated from the liquid phase and possible other phases (such as the solid char produced), that is, a reactor with a free surface, can be used.

[0205] According to a preferred embodiment, the reactor is a stirred reactor with a free surface.

[0206] According to a preferred embodiment, the reactor is substantially cylindrical in shape, with its axis being vertical.

[0207] The temperature of the material in the pyrolysis reactor can be measured by any method known in the art. For example, the following devices can be used: a thermocouple with a membrane-facing thermocouple aligned with the interior surface of the reactor to reduce contamination; a thermowell thermocouple for more accurate measurement inside the reactor; a thermocouple that measures the temperature of metal near the surface of the reactor wetted by the polymer; or a non-contact measurement system, such as infrared. Multiple systems can be used simultaneously to improve reliability.

[0208] The reactor elements in contact with this heat transfer fluid are separated from the reactor elements in contact with the process fluids (plastic inlet, liquefied plastic, char, gases produced by pyrolysis, etc.).

[0209] Preferably, the heat transfer fluid flows in the jacket. Optionally, the heat transfer fluid also flows inside the stirrer, so that an improved heating of the liquid substance is obtained.

[0210] Preferably, the heat transfer fluid is a molten salt. Any molten salt can be used in the present invention.

[0211] The heat transfer fluid may be a low melting temperature alkali metal of Group (III)A, Group (IV)A and Group (V)A (i.e., a metal alloy in which the elements belong to Group (III)A to Group (V)A of the periodic table) and a metal alloy based on Group (III)A, Group (IV)A and Group (V)A. Alkali metals include cesium (mp 28°C), lithium (180°C), potassium (63°C), neodymium (39°C), sodium (mp 98°C); (III)A, (IV)A and (V)A low melting temperature metals include indium (mp 157°C), gallium (mp 30°C), bismuth (mp 271°C), lead (mp 327°C), tin (mp 232°C); (III)A, (IV)A and (V)A metal alloys, which are metal alloys in which the total amount of elements belonging to Groups (III)A to (V)A of the periodic table reaches at least 70% by weight, such as Wood's metal (50% bismuth, 26.7% lead, 13.3% tin, and 10% cadmium, mp 70°C), Field's metal (32.5% Bi, 51% In, 16.5% Sn, mp 62°C), Rose's metal (50% bismuth, 25-28% lead and 22-25% tin, mp 98°C), Pewter metal (tin (85-99%), antimony (about 5-10%), copper (2%), bismuth, mp about 170-240°C), cast metal (40% Bi, 60% Sn, mp 170°C), lead-antimony eutectic (12% Sb, 88% Pb, mp 252°C), lead-tin eutectic (61.9% Sn, 38.1% Pb, mp 184°C), gallium-indium-tin alloy (68.5% Ga, 21.5% In, and 10.0% Sn, mp -19°C).

[0212] Among the low melting temperature alkali metals, sodium and potassium are preferred; among the metals of Group (III)A, Group (IV)A and Group (V)A, lead, bismuth, indium, gallium and tin are preferred; among the metal alloys based on Group (III)A, Group (IV)A and Group (V)A, Wood's metal, Field's metal, Ross's metal, white gold metal, foundry metal and gallium indium tin alloy are preferred.

[0213] According to one embodiment, the molten salt is a molten salt of Group IA and Group IIA of the periodic table, preferably sodium nitrate, sodium nitrite, potassium nitrite, potassium nitrate, lithium nitrate, calcium nitrate or a mixture thereof.

[0214] According to one embodiment, the molten salt that can be used is a nitrate / nitrite mixture, in particular a mixture of potassium nitrate and sodium nitrate, optionally with the addition of sodium nitrite and calcium nitrate.

[0215] According to one embodiment, the nitrate / nitrite mixture is a eutectic mixture of 53 wt% potassium nitrate, 40 wt% sodium nitrite, and 7 wt% sodium nitrate; alternatively, according to another embodiment, the K / Na nitrate / nitrite mixture is a eutectic mixture of 45.5 wt% potassium nitrate and 54.5 wt% sodium nitrite.

[0216] According to one embodiment, this nitrate / nitrite mixture is a so-called "solar salt" characterized by 60% by weight of sodium nitrate and 40% by weight of potassium nitrate.

[0217] According to one embodiment, this nitrate / nitrite mixture is the so-called "Hitec XL" characterized by 7 wt% sodium nitrate, 45 wt% potassium nitrate and 48 wt% calcium nitrate.

[0218] According to one embodiment, the nitrate / nitrite mixture is 100 wt% lithium nitrate.

[0219] According to one embodiment, the nitrate / nitrite mixture is 25 wt% lithium nitrate, 25 wt% sodium nitrate and 50 wt% potassium nitrate.

[0220] According to one embodiment, the molten salt is a mixture of chlorides such as sodium chloride and a mixture of sodium chloride and potassium chloride, optionally together with magnesium chloride.

[0221] According to other embodiments, the heat transfer fluid is a molten salt comprising Group IA and Group IIA metal fluorides, preferably lithium fluoride, sodium fluoride, potassium fluoride, and calcium fluoride. More preferably, the heat transfer fluid is composed of a molten salt comprising sodium nitrite, sodium nitrate, and potassium nitrate. Even more preferably, the heat transfer fluid is composed of a molten salt comprising sodium nitrate and potassium nitrate.

[0222] Preferably, the heat transfer fluid has a low melting temperature. More preferably, the melting temperature is at most 310°C, more preferably at most 250°C, and even more preferably at most 220°C. Preferably, the heat transfer fluid has a high decomposition temperature. More preferably, the decomposition temperature is at least 400°C, more preferably at least 450°C, more preferably at least 490°C, and even more preferably at least 540°C.

[0223] Preferably, the heat transfer fluid has a low chloride content. Preferably, the chloride content is less than 1000 ppm by weight. More preferably, the chloride content is less than 100 ppm by weight.

[0224] According to one embodiment, any component of the process intended to contain molten salts, such as, for example, reactors, cokers, preheaters, valves, etc., can be drained by gravity. According to another embodiment, any component containing molten salts characterized by the presence of moving parts (such as valves) or a large aspect ratio (e.g., pipes) has an electric heating line that can be activated before starting the machine equipment in order to melt the heat carrier medium.

[0225] The solar collector and receiver can be of any type. According to one embodiment, the solar collector is "single-focus," meaning that the sun's rays are reflected into a focal area that is substantially limited in size. Examples of "single-focus" solar collectors are parabolic dishes and power pylons. According to another embodiment, the solar collector is "focal line," meaning that the sun's rays are reflected into a focal area that is substantially a line. Examples of such solar collectors are parabolic troughs and linear Fresnels.

[0226] Preferably, the solar collector is a parabolic trough or a linear Fresnel.

[0227] The solar rays collected by this collector are reflected to a so-called solar receiver. In one embodiment, this solar receiver consists of a heat exchanger in which a heat-carrying fluid is heated. Typically, in this receiver, the fluid flows in tubes heated by the solar rays.

[0228] In another embodiment, the solar receiver consists of a tube into which the sun's rays are directed. This tube, usually a metal tube, is called the "absorber." It is coated with a selective coating that maximizes sunlight absorption while minimizing heat loss through infrared emission. The glass tube surrounding the absorber tube is transparent to allow sunlight to pass through. Between the two tubes, a high vacuum is created to limit convective heat loss. Degassing nozzles and / or getters are sometimes added to maintain this vacuum over time.

[0229] The ends of the solar receivers have bellows to account for the differential thermal expansion of the glass and metal materials.

[0230] The solar collectors and associated receivers can be assembled in parallel, in series, or in a combination of parallel and series. The combination of parallel and series is preferred.

[0231] The concentration coefficient is the ratio of the radiant power density at the receiver divided by the radiant power density of sunlight without any concentration, and is therefore the coefficient of optical enhancement of the incident energy flux on the receiving surface. The concentration coefficient according to the present invention is 8 to 1000, more preferably 10 to 100, and even more preferably 15 to 80.

[0232] Hot and cold storage tanks can be any containers that can be filled with heat-carrying fluid, such as vertical or horizontal tanks. Advantageously, these containers are thermally insulated in order to limit heat losses.

[0233] According to one embodiment, the heat transfer fluid pump 66 is located inside the storage tank.

[0234] According to one embodiment, the level of the heat transfer fluid in the storage tank is monitored in order to limit the pyrolysis load if the level of the heat transfer fluid in the hot storage tank becomes too low.

[0235] According to one embodiment of the invention, there is also an additional reservoir for the heat transfer fluid in order to deliver heat transfer fluid at more than two temperatures to the pyrolysis device.

[0236] According to one embodiment, this first pyrolysis reactor is a vertical vessel, preferably having a substantially cylindrical shape.

[0237] Preferably, the top and bottom ends of the first pyrolysis reactor are conical, elliptical or semi-elliptical. In this way, better recirculation is performed and less pollution is observed. Pollution is in fact a critical issue in pyrolysis reactors.

[0238] Preferably, the first pyrolysis reactor (70) has at least one agitator. This agitator should be of appropriate size to ensure continuous or semi-continuous wiping of the entire volume of the reactor, which is filled with at least the liquid and solid phases (e.g., not necessarily the gas phase). Preferably, the agitator should be able to regularly move material near the walls of the reactor in order to clean the surface and reduce contamination.

[0239] Examples of such a stirrer are an anchor stirrer or a ribbon stirrer, or in some cases a turbine stirrer.

[0240] The speed of this stirrer is generally from 1 to 300 rpm, preferably from 5 to 120 rpm.

[0241] According to some embodiments, multiple agitators can be used. In this case, the agitators advantageously have different agitator speeds. A simple way to accomplish this is to keep one agitator spinning freely so that it is entrained by the fluid to a rotational speed that is lower than that of one of the actively operating agitators, but greater than zero.

[0242] The term "condenser" means any device that receives a fluid in a gaseous state and is capable of removing sufficient heat from the fluid to produce at least a portion of the fluid in a liquid state.

[0243] An example of a device is a condenser comprising a coil inside which flows a heat-carrying fluid capable of removing heat from the gaseous fluid being processed.

[0244] Other methods of removing heat may also be used, for example, the condenser may have a jacket in which the heat transfer fluid flows, which is able to remove heat, instead or in combination.

[0245] It is also possible to advantageously use submerged condensers, in which the condenser is partially submerged by the generated liquid phase and its condensing power is adjusted by varying the height of this liquid phase, since only the unsubmerged coils are able to absorb calories from the vapor to be condensed. This therefore allows for efficient regulation of the power of the capacitor.

[0246] Alternatively, the condenser can consist of a distillation column. In this case, the condensed fluid originates in the column's condenser, and the condensed liquid flows back into the column by gravity or by pumping, condensing the vapor inside it. This method also achieves better fractionation of the incoming vapor, i.e., a better separation is achieved between the condensed higher-boiling components and the lower-boiling components that remain in the vapor phase, since, in each phase, there is a concentration of the heavy substances in the liquid phase and the light substances in the gaseous phase. Furthermore, the scrubbing of the vapor by the column operation allows any solid particles present in the incoming vapor to separate and reassemble in the liquid phase.

[0247] The condenser of the pyrolysis vapor can be a single condenser or a plurality of condensers in series or in parallel. Preferably, when a plurality of condensers are used, two to four condensers in series are used, even more preferably three condensers in series.

[0248] When the condensers are connected in series, each condenser receives the uncondensed gas leaving the previous condenser while the first condenser receives the pyrolysis vapor.

[0249] In this preferred mode, the condenser receiving the pyrolysis vapor (the first condenser) operates at a higher temperature than the second condenser receiving the uncondensed vapor from the first condenser. If there are more condensers, the next condenser (e.g., the third condenser) receives the uncondensed vapor from the previous condenser and operates at a lower temperature.

[0250] According to a preferred method, part of the fluid in liquid state condensed in the at least one condenser is recycled to the pyrolysis reactor.Preferably, the fluid recycled to the reactor is obtained from the first condenser.

[0251] According to one embodiment, when multiple condensers are used, as already described Figure 3 As described in , heat is removed by the heat transfer fluid through the first condenser (condenser 72A).

[0252] The hydrocarbon-containing fluid that remains uncondensed after passage through the at least one condenser, hereinafter defined as residual gas, advantageously contains at least 40% by weight of light hydrocarbons (C1-C5) and can advantageously be used as fuel gas. A portion of this gas can be combusted to supply additional heat energy suitable for the pyrolysis process. For this purpose, for example, a gas heater can be used that regulates the temperature of the heat transfer fluid circulating in the reactor jacket. Alternatively or in combination, this residual gas can advantageously be used to supply a refinery, such as, for example, a cracking plant.

[0253] According to one embodiment of the present invention, C5-C12 compounds are also obtained in the pyrolysis oil. The yield of C5-C12 compounds in the pyrolysis oil is at least 18%, preferably at least 28%, and more preferably 38% to 85%. According to one embodiment of the present invention, C5-C12 hydrocarbons are also obtained in the pyrolysis oil. The yield of C5-C12 hydrocarbons in the pyrolysis oil is at least 15%, preferably at least 25%, more preferably at least 30%, and even more preferably 35% to 80%. According to one embodiment of the present invention, the LHC fraction is at least 70%, preferably at least 85%, and more preferably 96% to 99.9%.

[0254] According to the present invention, the amount of liquid fluid (i.e., pyrolysis oil) after condensation in the at least one condenser is at least 10% by mass, preferably 20% to 92%, more preferably 30% to 85%, and even more preferably 40% to 75% relative to the mass of the substantially plastic material fed. If multiple condensers are used, this amount is calculated by adding the mass amounts of liquid produced by each condenser.

[0255] According to the invention, after condensation in the at least one condenser, at least one fluid is formed, which is in liquid state and contains hydrocarbons having a normal boiling point of not less than 25°C, preferably not less than 40°C, even more preferably between 80°C and 220°C.

[0256] For example, due to the use of steam or the presence of water in the plastic material, other liquid phases (such as a water-rich aqueous phase) may be formed. The other liquid phase can be separated from the hydrocarbon-rich phase by standard equipment such as a separator, or even by removing it from the bottom of the container where the liquid is condensed (because the aqueous phase is generally heavier than the organic phase containing hydrocarbons).

[0257] In this context, at least one fluid that is in a liquid state and contains hydrocarbons having a normal boiling point of not less than 25° C. is specified as the organic phase containing hydrocarbons.

[0258] Preferably, at least the first pyrolysis reactor is operated at a pressure that is atmospheric pressure or superatmospheric pressure (i.e., greater than atmospheric pressure). According to one embodiment, the pressure is between 1.1 bar and 20 bar, preferably between 2 bar and 10 bar, and more preferably between 2.1 bar and 6 bar.

[0259] Preferably, the temperature reached by the substantially plastic material in the first pyrolysis reactor is from 330°C to 580°C, preferably from 340°C to 540°C, more preferably from 360°C to 500°C, even more preferably from 380°C to 480°C, most preferably from 410°C to 450°C.

[0260] According to one embodiment, the residence time of the substantially plastic material in the first pyrolysis reactor is at least 20 minutes, preferably from 1 hour to 15 hours, even more preferably from 2 hours to 8 hours. If the first pyrolysis reactor is operated in batch mode, the residence time is calculated as the period of time during which the substantially plastic material is at a temperature of at least 300° C. If the first pyrolysis reactor is operated in continuous or semi-continuous mode, the residence time is calculated as the ratio of the volume of the reactor not occupied by a separate gas phase to the volume flow of the substantially plastic material entering the reactor.

[0261] The heating of the substantially plastic material in the pyrolysis reactor is obtained by the flow of the heat transfer fluid in the reactor. Thus, when good stirring is ensured, the temperature of the liquid, solid and semi-solid mixture in the pyrolysis reactor is close to the temperature of the heat transfer fluid flowing in the reactor.

[0262] According to an alternative embodiment, the temperature 21 used for controlling the process pressure (regulator 22, controller 23) is the temperature of the non-gaseous phase (liquid, solid or semi-solid phase) in the pyrolysis reactor.

[0263] In fact, since the pyrolysis reactor is heated by a heat-carrying fluid, the temperature of the non-gaseous phase in the pyrolysis reactor is closely related to the temperature of the heat-carrying fluid.

[0264] Any technique known in the art can be used to maintain the pressure in the pyrolysis reactor at a defined value, wherein this maintained pressure can have different values ​​that vary with the pyrolysis temperature. According to a first method, the pressure can be maintained at a defined value by regulating the amount of heat removed from a condenser located downstream of the reactor and in fluid communication therewith. In this mode, the increased heat removed from the condenser results in greater vapor condensation. This condensation, which causes the evaporated material to transition from a gaseous state to a liquid state with a greater density, results in a decrease in pressure.

[0265] Alternatively, the pressure can be controlled by introducing a gas such as nitrogen, argon or water vapor and by regulating the flow of this gas through a valve. According to one embodiment, this gas is introduced into the pyrolysis reactor and also serves as an inert gas (i.e., a gas that does not directly participate in the pyrolysis reaction and that can displace the oxygen present in the reactor when it is connected to the atmosphere, for example during maintenance or before reactor startup).

[0266] According to a preferred embodiment, the pressure is controlled by adjusting the flow of the uncondensed gas stream (the gas stream of the last condenser if multiple condensers in series are used).

[0267] The thermal power of the first pyrolysis reactor and the second pyrolysis reactor can be regulated by controlling the flow rate, the temperature, or both of the heat transfer fluids.

[0268] According to one embodiment, the pyrolysis of the substantially plastic material of the present invention is performed in the substantial absence of oxygen, wherein "substantially absent of oxygen" has the meaning as previously defined. Advantageously, the pyrolysis process of the present invention produces a product that is particularly suitable for use as jet fuel or as a crude naphtha that is particularly suitable for steam cracking to produce monomers of industrial interest, or for synthesizing polymers.

[0269] The second pyrolysis reactor operates at a temperature higher than that of the first pyrolysis reactor. Preferably, the temperature difference between the second pyrolysis reactor and the first pyrolysis reactor is at least 10°C, preferably 30 to 300°C, even more preferably 60 to 250°C.

[0270] The residence time of the pyrolysis vapors, calculated divided by the volume occupied by the vapors and the volume flow rate in the reactor, is at least 20 seconds, preferably 30 seconds to 6 minutes, more preferably 1 minute to 4 minutes.

[0271] Preferably, the second pyrolysis reactor is catalytic. This means that a catalyst, preferably a solid catalyst, is present inside the second pyrolysis reactor and the pyrolysis vapor is in contact with the catalyst. More preferably, the gaseous effluent is in relative motion with respect to the solid catalyst in contact with the gaseous effluent, and the relative motion is at a speed of at least 10 m / s, more preferably 20 m / s to 300 m / s.

[0272] All pyrolysis catalysts known in the art to which the present invention pertains can be used, including in particular zeolites.

[0273] According to one embodiment, the method of the invention for producing at least one pyrolysis oil from a substantially plastic material using a variable intensity energy source comprises the following steps:

[0274] a) heating a heat transfer fluid to a temperature (THTF) comprised between 350° C. and 700° C. by means of a variable intensity energy source;

[0275] b) heating the first pyrolysis reactor by means of a heated heat transfer fluid;

[0276] c) feeding the substantially plastic material, optionally already in a molten and / or preheated state, to a first pyrolysis reactor;

[0277] d) using the variable intensity energy source, in the substantial absence of oxygen and at a pressure of from atmospheric pressure to 20 bar(a), bringing the substantially plastic material in the first pyrolysis reactor to a temperature of from 330°C to 650°C;

[0278] e) maintaining the substantially plastic material in the first pyrolysis reactor at a temperature of 330° C. to 650° C. for a period of time sufficient to produce at least one gaseous effluent in the first pyrolysis reactor;

[0279] f) keeping the composition of the produced pyrolysis oil substantially constant by dynamically adjusting the pressure in the first pyrolysis reactor to a value between atmospheric pressure and 20 bar (a) relative to a reference temperature (TREF), the reference temperature being the temperature of the heated heat transfer fluid (THTF) or the temperature of the material in the first pyrolysis reactor (TMPR);

[0280] g) partially or completely condensing the effluent in the gaseous state so as to form at least one liquid fluid representing in an amount of at least 10% by mass relative to the mass of the fed substantially plastic material and comprising hydrocarbons having a normal boiling point not lower than 25°C.

[0281] In step f), "maintaining the composition of the produced pyrolysis oil substantially constant by dynamically adjusting the pressure in the first pyrolysis reactor relative to a reference temperature (TREF)" means that the composition of the pyrolysis oil may vary within certain tolerances. The tolerances are such that those skilled in the art understand that the pyrolysis oil's functionality is not affected, namely, achieving a yield of at least 18% for C5-C12 compounds in the pyrolysis oil and a yield of at least 15% for C5-C12 hydrocarbons in the pyrolysis oil, and relative preferred values.

[0282] In addition, "dynamic adjustment" means that the adjustment is not performed once, but is repeated from time to time. This adjustment frequency may be at least once every 8 hours, preferably at least once every hour, and even more preferably once every minute.

[0283] According to one embodiment, the variable intensity energy source is a solar source through concentrated solar power (CSP), solar photovoltaics, wind, tides, and combinations thereof. Preferably, according to one embodiment, the variable intensity energy source is solar photovoltaics, a solar source through concentrated solar power (CSP), even more preferably a solar source through concentrated solar power (CSP).

[0284] According to one embodiment, there is additionally a second energy source of a different type than the variable intensity energy source and wherein the heating of step (a) is performed by both the variable intensity energy source and the second energy source.

[0285] Preferably, the second energy source is electricity or heat from fossil, biomass (especially biomethane or renewable natural gas) or nuclear fuels, and combinations thereof.

[0286] According to one embodiment, the method for producing at least one pyrolysis oil from a substantially plastic material according to the invention comprises the following additional steps:

[0287] a2) The heat transfer fluid heated at the temperature (THTF) is stored in a storage tank.

[0288] According to one embodiment, the method disclosed herein produces at least one pyrolysis oil from a substantially plastic material, wherein the pressure adjustment of step (f) relative to a reference temperature (TREF) being the temperature of the heated heat-transfer fluid (THTF) or the temperature of the material in the pyrolysis reactor (TMPR) is performed by increasing the pressure when the temperature (TREF) decreases and decreasing the pressure when the temperature (TREF) increases, so that the resulting pressure-temperature value corresponds to a pressure-temperature value of a set of predetermined pressure-temperature values ​​obtained according to the interpolation described below.

[0289] It should be understood that according to another embodiment, the adjusted temperature used in step (f) is the temperature of the liquid / solid / semi-solid matter contained in the pyrolysis reactor.

[0290] Different regulation schemes are possible. According to one embodiment of this control scheme, the pressure regulation of step (f) relative to a reference temperature (TREF) being the temperature of the heated heat transfer fluid (THTF) or the temperature of the material in the pyrolysis reactor (TMPR) is performed by a method providing the following operation: setting a lower temperature threshold (TTL) and an upper temperature threshold (TTU), and when the temperature (TREF) is within the lower temperature threshold (TTL) and the upper temperature threshold (TTU), by increasing the pressure when the temperature (TREF) decreases, and vice versa, wherein the increase or decrease in pressure is preferably calculated according to an interpolation equation of the temperature-pressure relationship between TTL and TTU, the method further comprising keeping the pressure constant when the temperature (TREF) is above the upper temperature threshold or below the lower temperature threshold.

[0291] According to one embodiment, the interpolation equation for the temperature-pressure relationship between TTL and TTU is a linear interpolation. This means that in a graph of pressure (ordinate) versus temperature (abscissa), the operating line is the line between the points (TTL, PLU) and (TTU, PLL); thus, according to this embodiment, for a temperature TREF between TTL and TTU, the pressure set point (PMPR) is the ordinate value of this line at a given abscissa value.

[0292] According to an alternative embodiment, the interpolation equation of the temperature-pressure relationship between TTL and TTU is a monotone non-increasing piecewise linear function passing through the (TTL, PLU) and (TTU, PLL) endpoints, in particular a monotone non-increasing piecewise constant function, such as a monotone non-increasing piecewise constant function derived by a linear combination of at least one Heaviside (step) function, preferably 2 to 10 Heaviside (step) functions.

[0293] According to an alternative embodiment, the interpolation equation for the temperature-pressure relationship between TTL and TTU is a generalized logic function, preferably a sigmoid function (also called "logistic function"), passing through the (TTL, PLU) and (TTU, PLL) endpoints.

[0294] Preferably, the interpolation equation of the temperature-pressure relationship between TTL and TTU is a linear interpolation or a piecewise constant function or a generalized logic function, more preferably a linear interpolation or a piecewise constant function, even more preferably a linear interpolation function.

[0295] Therefore, according to one embodiment of the present invention, the method of the present invention is characterized in that when the temperature is between the lower temperature limit (TTL) and the upper temperature limit (TTU), the pressure is set to a value obtained by an interpolation equation of the temperature-pressure relationship, wherein preferably the interpolation equation is a linear interpolation or a piecewise constant function or a generalized logical function.

[0296] The pressure is set by fixing the target pressure setting value to a given value by the pressure manager (22), so that the pressure controller (23) can regulate the pressure of the (first) pyrolysis reactor to the target value, as described above.

[0297] According to a possible control sub-flow that can be used for any interpolation equation, when the temperature (TREF) is equal to or lower than the lower temperature threshold (TTL), the pressure is set to an upper limit pressure (PLU), and when the temperature (TREF) is equal to or higher than the upper temperature threshold (TTU), the pressure is set to a lower limit pressure (PLL).

[0298] In this case, preferably, the lower limit pressure (PLL) is comprised between atmospheric pressure and 3 bar(a), more preferably between atmospheric pressure and 2.1 bar(a), even more preferably atmospheric pressure, and the upper limit pressure (PLU) is 3.2 bar(a) or above, more preferably between 3.5 bar(a) and 10 bar(a), even more preferably between 4 bar(a) and 6 bar(a). In this case, preferably, the lower temperature threshold (TTL) is between 350°C and 500°C, more preferably between 380°C and 440°C, even more preferably between 400°C and 420°C, and the upper temperature threshold (TTU) is between 400°C and 700°C, more preferably between 420°C and 480°C, even more preferably between 440°C and 460°C, with the supplementary provision that the upper temperature threshold in any case exceeds the lower temperature threshold by at least 10°C, preferably by at least 20°C, even more preferably by at least 40°C.

[0299] The variability of the temperature within a specific range is due to the fact that different plastic materials to be processed (e.g., different Plas Mix compositions) require different process temperatures. For example, under equal process conditions, such as, in particular, residence time, LDPE requires a higher process temperature than PS polymer (see, for example, Tuffi et al., Express Polymer Letters, Vol. 12, No. 1 (2018) 82-99). A skilled person knows how to vary the temperature based on the variability of the raw materials (i.e., the existence of data highlighting the degradation temperatures of various plastics), for example by performing a thermogravimetric analysis (TGA) on a sample of essentially the raw plastic material at a standard rate of 10°C / min and determining the temperature corresponding to 50% weight loss. He / she can therefore also compensate the range relative to the range given above in order to obtain similar results for other plastic material compositions, for example, using the value at 50% weight loss in the TGA for the upper limit (TTU) and the same value of less than 40°C for the lower limit (TTL).

[0300] Some adjustment schemes are shown in Figure 5 In this figure, three different interpolation equations are graphically shown: from top to bottom, a linear relationship, a monotonic non-increasing piecewise constant function, and a generalized logistic function. For each case, a graph is provided with the pyrolysis temperature on the horizontal axis and the pyrolysis pressure on the vertical axis. In all cases, outside the temperature range between the lower temperature threshold (TTL) and the upper temperature threshold (TTU), the set point of the pyrolysis pressure (PMPR) (set by the pressure manager 22) remains constant at the values ​​at these endpoints (i.e., for temperatures TREF not higher than TTL, PMPR is equal to PLU, and for temperatures TREF not lower than TTU, PMPR is equal to PLL). When the temperature TREF is within the range (TTL, TTU), the pressure set point PMPR is set according to the corresponding interpolation equation.

[0301] Linear interpolation is generally effective and appears stable, but it has the disadvantage that the pressure set point always changes even with small changes in the pyrolysis temperature. This can be troublesome for some pressure regulators that require the set point to remain unchanged for some time. In this case, a piecewise constant function can be more effective. Finally, the generalized logistic function can remove the discontinuity of the first derivative at the endpoints (TTL, TTU) because the derivative of this function at the endpoints is approximately zero. Therefore, this interpolation equation appears to be particularly stable for PID control (23) with a significant derivative component.

[0302] According to one embodiment of the invention, step (f) comprising dynamically adjusting the pressure relative to the temperature of the heated heat-carrying fluid is performed with a latency of at most 120 seconds, preferably 0.1 to 60 seconds.

[0303] Latency means the time delay between measuring the temperature and defining the pressure set point and therefore includes the time required for temperature measurement, optional data filtering, evaluation of the pressure set point and its definition.

[0304] Example

[0305] Original Materials

[0306] It was considered appropriate to use primarily new raw materials, whose composition was therefore known and constant, thus facilitating experimental reproducibility. By preparing suitable mixtures of raw materials, it was possible to evaluate the effects of different pyrolysis conditions on the compositional variability of the plastic material source. Furthermore, this method allowed the preparation of a mixture representing an average "Plas Mix," which is the residue after sorting recycled plastic material.

[0307] In fact, multiple Plas Mix samples were collected and analyzed over time, from which the average composition was determined and used to prepare the mixes used in this example.

[0308] The polymer materials used are as follows:

[0309]

[0310]

[0311] The table below shows the atomic composition (weight percent) of the materials used.

[0312]

[0313] The inorganic materials used are as follows:

[0314]

[0315] Prepare the mixture

[0316] First, a masterbatch of inorganic additives (referred to as MBINORG) was prepared by mixing and extruding the following composition in a twin-screw extruder:

[0317]

[0318] The following mixture ("PYROMIX-1") was then prepared in the dry blend:

[0319]

[0320] The above compositions were prepared in order to simulate the typical composition of substantially plastic materials as found in Plas Mix. In fact, the substantially average composition of a number of Plas Mix samples was analyzed in order to assess the type of plastic and the different inorganic materials contained therein.

[0321] Pyrolysis device used in the examples

[0322] The pyrolysis apparatus used in the embodiment ("A1") of the present invention consists of the following:

[0323] - a pyrolysis reactor equipped with a flange for loading the material, a dip tube for feeding inert gas (nitrogen), a nozzle for the inlet of the essentially plastic material, a nozzle for the outlet of the pyrolysis vapors, openings (NT1, NT2, NT3) for measuring the temperature of the liquid / solid / semisolid substance inside the reactor by means of thermocouples (3-point measurement for better accuracy), and a nozzle (NP1) for measuring the pressure;

[0324] - a flow meter equipped with a fine adjustment valve that regulates the rate of inert gas flow into the reactor;

[0325] - a pressure transducer located on top of the reactor, which reads the pressure of the gas inside the reactor;

[0326] - three thermocouples, used to measure the actual temperature of the liquid / solid / semi-solid matter inside the reactor and therefore located in the lower part of the reactor;

[0327] -Electric heating jacket with thermal insulation system;

[0328] - a reactor temperature regulation system which reads the temperature value of one of the three thermocouples and regulates the electric heating power in feedback whose control parameters are suitably calibrated in order to ensure high thermal stability (temperature fluctuations below 5° C.);

[0329] - a condenser for condensing the vapors leaving the reactor, which is kept at -10°C by flowing a cooling fluid from a refrigeration unit at a controlled temperature;

[0330] - a valve for regulating the flow of gas leaving the reactor, located between the reactor and the condenser;

[0331] a reactor pressure regulation system which reads the pressure value of the pressure converter and acts on the regulating valve via feedback in order to ensure high pressure stability (pressure fluctuations below 50 mbar);

[0332] - an expandable flask connected gastightly to the upper outlet of the condenser intended to collect the uncondensed gaseous fraction;

[0333] a receiving container connected in a gas-tight manner to the lower outlet of the condenser intended to collect the condensed portion and therefore in liquid state, the container having a vent connected to the upper outlet of the condenser;

[0334] - Nitrogen inlet valve;

[0335] - a shut-off valve between the outlet of the liquid product leaving the condenser and its sealed connection to the receiving vessel;

[0336] - A shut-off valve between the outlet for the gaseous products leaving the condenser and the sealed connection to the expandable flask.

[0337] The reactor is vertical and has a generally cylindrical profile.

[0338] Pyrolysis Examples (Comparative and According to the Invention)

[0339] The examples were prepared using a dry blended mixture of the polymer and the inorganic compound PYROMIX-1.

[0340] The following table shows the conditions of each embodiment.

[0341]

[0342] The dry blended mixture was charged into the reactor of "Apparatus 1" as described above. The occupied volume in the reactor was about 1 / 3 of the geometric volume.

[0343] The valve used to regulate the flow of pyrolysis vapors leaving the reactor was manually set to fully open.

[0344] Nitrogen is then injected from below through the dip tube, fully opening the fine adjustment valve of the flow meter.

[0345] The gas contained in the reactor was then removed over a period equal to 24 hours in order to ensure complete elimination of oxygen.

[0346] The valves on the outlets for the gaseous and liquid products from the condenser are then closed. Immediately thereafter, the nitrogen supply is interrupted. An expandable flask for collecting the produced gas and a receiving vessel for collecting the produced liquid are connected.

[0347] The valves on the outlets for the gaseous and liquid products from the condenser are then reopened.

[0348] The valve regulating the gas flow leaving the reactor was set to automatically adjust at the value chosen for the test (P_pyro, as given in the table).

[0349] Nitrogen is then injected from below via the dip tube, but at a very low flow rate, chosen so that the amount of gas collected in the inflatable balloon before its displacement does not exceed 30% of the balloon's maximum volume.

[0350] The following program is loaded into the thermal regulation system of the pyrolysis reactor:

[0351] 1. First heating ramp: 4 degrees per minute until the pyrolysis temperature T_pyro is reached;

[0352] 2. Maintain temperature T_pyro for 6 hours;

[0353] 3. Disconnect heating.

[0354] The reactor thermal regulation system was turned on.

[0355] 12 hours after the end of the program, the reactor temperature was checked to be below 60° C. Then, the nitrogen supply was interrupted, the interception valves on the liquid and gaseous product outlets leaving the condenser were closed and the reactor flange was opened.

[0356] There was a semi-solid material in the reactor (corresponding to the material that was not converted into pyrolysis vapors). This material, called "char", was carefully removed from the reactor and weighed.

[0357] The reactor interior is carefully cleaned to remove any contamination that may have eventually formed.

[0358] The liquid (pyrolysis oil condensate) contained in the liquid receiving container was weighed and then ultracentrifuged at 25,000 rpm (Thermo Scientific ultracentrifuge model Sorvall Evolution RC) for 45 minutes.

[0359] Then, the material remaining on the bottom after ultracentrifugation (hereinafter described as wax) and the supernatant (hereinafter described as light oil) were separated and weighed.

[0360] The fraction of light oil ("light oil fraction") was calculated by dividing the weight of light oil by the weight of material initially fed to the reactor (the dry blended mixture).

[0361] Similarly, the wax fraction ("wax fraction") is calculated by dividing the weight of wax by the weight of material initially fed to the reactor (the dry blended mixture).

[0362] Similarly, the fraction of char ("char fraction") is calculated by dividing the weight of semi-solid material extracted from the reactor by the weight of material initially fed to the reactor.

[0363] The mass of gas produced is calculated as the difference between the weight of the material initially fed to the reactor and the sum of the weights of the char and pyrolysis oil fractions (the latter being the sum of light oil and wax). The fraction of non-condensable gas produced ("gas fraction") is calculated by dividing the mass of the gas fraction thus calculated by the weight of the material initially fed to the reactor.

[0364] Gas Chromatographic Analysis Method for Light Oil Samples

[0365] Light oil samples were characterized by gas chromatography. Compounds were first qualitatively identified by coupled gas chromatography-mass spectrometry (GC-MS) and then quantified by gas chromatography with a flame ionization detector (GC-FID).

[0366] The following are the instrument parameters used for GC-FID analysis:

[0367] -GC: Agilent HP 7890B equipped with a Gerstel MPS autosampler

[0368] - Tower: HP-PONA Agilent Technologies J&W-50m-0.2mm-0.5μm,

[0369] -Carrier (H2): 1.1mL / min constant flow

[0370] -Syringe: 320°C, 255:1 split, 3mm (Ultra Inert) liner with glass wool

[0371] -Detector: 360℃

[0372] - Oven: Tower temperature program: 20°C for 5 min, 2°C / min to 70°C for 5 min, 2°C / min at 160°C for 5 min, 2°C / min to 320°C for 30 min (run time: 195 min).

[0373] Each sample was analyzed by assigning an arbitrary response factor equal to one for all compounds; the concentrations obtained were then normalized to 100%.

[0374] The obtained fractions were analyzed using the techniques described above. Approximately 130 compounds were identified.

[0375] For each of these compounds, the number of atoms of each element (C, N, O, H) was calculated. Thus, the mass fraction of C, N, O, and H atoms can be calculated by summing the mass fraction of each atom in the compound.

[0376] Gas chromatography analysis mode of wax samples

[0377] This fraction was analyzed in different ways to allow identification of high molecular weight compounds.

[0378] In fact, these compounds may appear not to elute and analyze in gas chromatography analysis.

[0379] Before using the sample for GPC analysis, the pyrolysis oil contained in the Schott bottle was heated to 50°C to homogenize its contents (in some cases, characterized by a deposit and / or layer of waxy compounds at room temperature or cooled temperature). A few mg of the sample was dissolved in 1,2,4-trichlorobenzene (Baker) with the addition of 10 μL of n-heptane (internal marker) with heating (dissolution at 150°C for one hour) to obtain a concentration of approximately 1.8 mg / mL.

[0380] The analysis was performed on a chromatographic apparatus consisting of:

[0381] -High temperature carbon polymer GPC-IR

[0382] - Workbench with HT2 tower and front tower of 3TSK gel with 13μm size

[0383] -IR5 high temperature infrared detector that provides an absorption signal proportional to the number of methyl and methylene groups.

[0384] The experimental conditions used are as follows:

[0385] -Solubility agent: 1,2,4TAB stabilized with BHT

[0386] -Flow rate: 1mL / min

[0387] - Temperature: Pump at 25°C, Injector at 150°C, Column at 150°C, Detector at 150°C

[0388] -Injection volume: 200 μl

[0389] -Internal standard: n-heptane.

[0390] "C5-C12 wax fraction" means the sum of the masses of compounds having 5 to 12 carbon atoms (inclusive) in the wax relative to the total mass of the wax product.

[0391] The “C5-C12 light oil fraction” means the sum of the masses of compounds having 5 to 12 carbon atoms (inclusive) in the light oil relative to the total mass of the wax product.

[0392] "C5-C12 yield" means "C5-C12 light oil fraction" multiplied by "light oil fraction" plus "C5-C12 wax fraction" multiplied by "wax fraction." Thus, "C5-C12 yield" is the ratio of the mass of compounds with 5 to 12 carbon atoms in the pyrolysis oil product to the mass of the essentially plastic material fed to the pyrolysis reactor. This is the most relevant parameter in the results, as C5-C12 compounds are the most desirable compounds in closed-loop recycling of plastics.

[0393] In the table below, the C5-C12 yield, C5-C12 hc yield and lhc fraction are reported.

[0394]

[0395]

[0396] These parameters are very relevant because C5-C12 compounds are very desirable compounds for closed-loop recycling of plastics. Of these compounds, hydrocarbons are the most desirable compounds because, in most cases, compounds containing heteroatoms (such as sulfur, oxygen and nitrogen) must be separated in order to produce some high-quality virgin plastics, such as polyethylene, polypropylene, polystyrene.

[0397] It can be seen that in Example 1, the yield of C5-C12 is good (pyrolysis at 450°C at 2.1 bar(a)), but this yield is significantly reduced when the pyrolysis temperature is reduced by 40°C at the same pressure (410°C at 2.1 bar(a)).

[0398] However, when the pressure was increased to 5.1 bar (a) (Example 3), almost the same yield of the desired C5-C12 fraction could be obtained, although the temperature was the same as that of Comparative Example 2 (410°C).

[0399] Similarly, in Example 1, the yield of C5-C12 hydrocarbons was good (41.3%), but this yield decreased significantly (to 27.7%) when the pyrolysis temperature was reduced by 40°C at the same pressure.

[0400] However, when the pressure was increased to 5.1 bar (a) (Example 3), almost the same yield (38.1%) in C5-C12 hydrocarbons was obtained, although the temperature was the same as that of Comparative Example 2.

[0401] Finally, for Inventive Examples 1 and 3, the lhc fraction, which is the ratio of the C5-C12 hc yield to the C5-C12 yield, was very high (>96.5%). This means that the C5-C12 compounds in the pyrolysis oil are primarily composed of hydrocarbons, with non-hydrocarbon compounds accounting for less than 5% of the total. In contrast, Comparative Example 2 showed a significantly lower percentage of hydrocarbons (95.8%).

[0402] This means that a decrease in pyrolysis temperature due to a decrease in the power delivered by the intermittent or variable intensity energy source (eg when the sun goes down or some clouds reduce the solar power) can be compensated by increasing the process pressure.

Claims

1. A method for producing at least one pyrolysis oil from a substantially plastic material using a variable intensity energy source, the method comprising the steps of: a. heating the heat transfer fluid to a temperature (THTF) comprised between 350°C and 700°C by a variable intensity energy source; b. heating the pyrolysis reactor by heating the heat carrier fluid; c. feeding the substantially plastic material, optionally already in a molten and / or preheated state, to a pyrolysis reactor; d. using the variable intensity energy source, in the substantial absence of oxygen and a pressure of atmospheric pressure to 20 bar (a), causing the material in the pyrolysis reactor to reach a temperature (TMPR) of 330°C to 650°C; e. maintaining the material in the pyrolysis reactor at a temperature (TMPR) of 330° C. to 650° C. for a period of time sufficient to produce at least one gaseous effluent in the pyrolysis reactor; f. maintaining the composition of the produced pyrolysis oil substantially constant by dynamically adjusting the pressure in the pyrolysis reactor to values ​​between atmospheric pressure and 20 bar relative to a reference temperature (TREF), the reference temperature being the temperature of the heated heat transfer fluid (THTF) or the temperature of the material in the pyrolysis reactor (TMPR); g. partially or completely condensing said effluent in the gaseous state so as to form at least one liquid fluid, said fluid being in an amount of at least 10% by mass relative to the mass of the substantially plastic material fed and comprising hydrocarbons having a normal boiling point not lower than 25°C.

2. The method for producing at least one pyrolysis oil from a substantially plastic material according to claim 1 , wherein the pressure adjustment of step (f) relative to the reference temperature (TREF) is performed by increasing the pressure when the temperature (TREF) decreases and decreasing the pressure when the temperature (TREF) increases.

3. The method for producing at least one pyrolysis oil from a substantially plastic material according to claim 1 , wherein the pressure adjustment of step (f) relative to the reference temperature (TREF) is performed by: setting a lower temperature limit (TTL) and an upper temperature limit (TTU); and when the temperature (TREF) is within the lower temperature limit (TTL) and the upper temperature limit (TTU), increasing the pressure when the reference temperature (TREF) decreases, and vice versa; and maintaining the pressure constant when the reference temperature (TREF) is above the upper temperature limit or below the lower temperature limit.

4. The method for producing at least one pyrolysis oil from a substantially plastic material according to claim 3, wherein when the temperature (TREF) is equal to or lower than the lower temperature limit (TTL), the pressure is set to an upper pressure limit (PLU); and when the temperature (TREF) is equal to or higher than the upper temperature limit (TTU), the pressure is set to a lower pressure limit (PLL).

5. The method for producing at least one pyrolysis oil from a substantially plastic material according to claim 4, wherein the lower pressure limit (PLL) is comprised between atmospheric pressure and 3 bar(a), more preferably between atmospheric pressure and 2.1 bar(a); and the upper pressure limit (PLU) is 3.2 bar(a) or above, more preferably between 3.5 bar(a) and 10 bar(a), even more preferably between 4 bar(a) and 6 bar(a).

6. Method for producing at least one pyrolysis oil from a substantially plastic material according to any one of claims 3 to 5, characterized in that When the reference temperature (TREF) is between the lower temperature limit (TTL) and the upper temperature limit (TTU), the pressure is set to a value obtained by an interpolation equation of the temperature-pressure relationship, wherein preferably the interpolation equation is a linear interpolation or a piecewise constant function or a generalized logical function.

7. The method for producing at least one pyrolysis oil from a substantially plastic material according to any one of claims 1 to 6, wherein the variable intensity energy source is solar energy, wind energy, tidal energy and combinations thereof.

8. The method for producing at least one pyrolysis oil from a substantially plastic material according to claim 7, wherein the variable intensity energy source is solar energy, preferably by means of concentrated solar power (CSP).

9. Method for producing at least one pyrolysis oil from a substantially plastic material according to any one of claims 1 to 8, comprising the additional steps of: a2. The heat transfer fluid heated at the temperature (THTF) is stored in a storage tank.

10. A method for producing at least one pyrolysis oil from a substantially plastic material according to any one of claims 1 to 9, wherein a second energy source of a different type than the variable intensity energy source is additionally present, and wherein the heating of step (a) is performed by the variable intensity energy source and the second energy source.

11. The method of producing at least one pyrolysis oil from a substantially plastic material according to claim 10, wherein the second energy source is an electrical or thermal source derived from fossil, biomass (such as biomethane) or nuclear fuel, and combinations thereof.

12. Method for producing at least one pyrolysis oil from a substantially plastic material according to any one of claims 1 to 11, wherein step (f) comprising dynamically adjusting the pressure relative to the temperature of the heated heat transfer fluid is performed with a latency of at most 120 seconds, preferably 0.1 to 60 seconds.

13. Method for producing at least one pyrolysis oil from a substantially plastic material according to any one of claims 1 to 12, wherein the heat carrier fluid is a molten salt.

14. The method for producing at least one pyrolysis oil from a substantially plastic material according to claim 13, wherein the molten salt is a salt from Group IA and Group IIA of the periodic table, preferably sodium nitrate, sodium nitrite, potassium nitrite, potassium nitrate, lithium nitrate, calcium nitrate and mixtures thereof.

15. The method of producing at least one pyrolysis oil from a substantially plastic material according to claim 14, wherein the molten salt is a mixture of 60 wt% sodium nitrate and 40 wt% potassium nitrate; or a eutectic mixture of 53 wt% potassium nitrate, 40 wt% sodium nitrite and 7 wt% sodium nitrate; or a eutectic mixture of 45.5 wt% potassium nitrate and 54.5 wt% sodium nitrite.

16. The method for producing at least one pyrolysis oil from a substantially plastic material according to any one of claims 1 to 15, wherein the gaseous effluent of the pyrolysis reactor, before condensation in step (g), passes to a second pyrolysis reactor, wherein If no catalyst is used, the gaseous stream is heated to a temperature (TMSR) higher than the temperature (TMPR) of the substantially plastic material of step (e); or wherein, if a catalyst is used, the gaseous effluent of the pyrolysis reactor is, prior to condensation in step (g), optionally heated or cooled to a temperature (TMSR) higher or lower, respectively, than the temperature (TMPR) of the substantially plastic material of step (e) and then passed over the catalyst.

17. The method for producing at least one pyrolysis oil from a substantially plastic material according to claim 16, wherein the second reactor contains a catalyst, wherein the gaseous effluent of the pyrolysis reactor is contacted with the catalyst.

18. The method for producing at least one pyrolysis oil from a substantially plastic material according to any one of claims 1 to 17, wherein the condensation of step (g) is performed in a plurality of condensation units connected in series.

19. The method for producing at least one pyrolysis oil from a substantially plastic material according to any one of claims 1 to 18, wherein regulating the pressure in the pyrolysis reactor is performed by adjusting the pressure drop of the effluent of the pyrolysis reactor in a gaseous state prior to the condensation of step (g).

20. Method for producing at least one pyrolysis oil from a substantially plastic material according to claim 19, wherein regulating the pressure drop of the effluent in the gaseous state is performed by means of a throttling device, preferably a valve.

21. Process for producing at least one pyrolysis oil from a substantially plastic material according to any one of claims 1 to 20, wherein the substantially plastic material is preferably preheated to a temperature of 120°C to 360°C, even more preferably 150°C to 260°C, even more preferably 170°C to 230°C, even more preferably 180°C to 210°C, and optionally partially or completely melted before being fed to the pyrolysis reactor.

22. Process for producing at least one pyrolysis oil from a substantially plastic material according to any one of claims 1 to 21, wherein the solid, semi-solid or liquid material in the pyrolysis reactor is withdrawn and heated to a temperature of 500 to 1200°C, preferably 600 to 1000°C, even more preferably 700 to 900°C for a period of at least 5 minutes, preferably 15 to 180 minutes, even more preferably 30 to 120 minutes.

23. A plant for producing at least one pyrolysis oil from a substantially plastic material, said plant comprising: a. a pyrolysis reactor (70) having at least one inlet for feeding a substantially plastic material, an outlet for removing at least one gaseous effluent, and a jacket and / or coil having at least one inlet and one outlet for a molten salt; b. a condenser (72) receiving the gaseous effluent from the pyrolysis reactor; c. a solar collector and receiver assembly (61, 62), the receiver comprising at least one inlet and one outlet for a molten salt, wherein the solar collector is capable of delivering concentrated solar radiation to the solar receiver, which in turn is configured to heat the molten salt; d. a first storage tank ("cold storage tank", 63), the storage tank being fluidly connected to the outlet of the molten salt of the pyrolysis reactor (70) so as to receive and store the molten salt returned from the pyrolysis reactor (70), the first storage tank being fluidly connected to the inlet of the solar receiver (62); e. a second storage tank ("hot storage tank", 64) fluidly connected to the outlet of the solar receiver (62) for receiving and storing molten salt returned from the solar collector and receiver (SCA1), the second storage tank being fluidly connected to the inlet of the molten salt of the pyrolysis reactor (70); f. A controller (23) which, via a pressure manager (22), adjusts the pressure set point of the pyrolysis reactor (24) relative to the reference temperature TREF, the reference temperature being the temperature THTF (21A) of the molten salt from the second tank ("hot tank", C2) or the temperature TMPR (21B) of the material in the first pyrolysis reactor (70).

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