Process and associated plant for producing pyrolysis oil containing liquid hydrocarbons from plastic materials from intermittent energy sources

Abstract

A process for producing pyrolysis oil containing liquid hydrocarbons from plastic materials, preferably waste materials. The process is characterized by the use of an energy source, preferably of an intermittent nature (and variable intensity), such as solar radiation. The plastic material enters a pyrolysis reactor heated by a molten salt thermal fluid. The molten salt is heated by the intermittent source to a temperature that is not fixed but varies within a predetermined range. In particular, when the available amount of the energy source is equal to or exceeds a predetermined maximum value, the temperature of the molten salt is increased to the upper limit of the range. Conversely, when the available amount of the energy source is equal to or lower than a predetermined minimum value, the temperature of the molten salt is decreased to the lower limit of the range. For intermediate availability values, the temperature can also be intermediate, for example, by following a linear profile. The pyrolysis temperature follows the temperature of the molten salt. On the other hand, the pyrolysis pressure is adjusted to be higher (at least 2.5 bara) for lower pyrolysis temperatures and lower (up to 2 bara) for higher pyrolysis temperatures. Surprisingly, it has been discovered that by operating in a specific manner, the quality of the resulting pyrolysis oil remains constant even when the pyrolysis temperature fluctuates widely.

Description

[Technical Field]

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

[0002] It is applied in the field of pyrolysis of plastic materials to produce pyrolysis oil containing hydrocarbons, which after further processing can be converted into monomers useful for the production of polymers, thus closing the loop. [Background technology]

[0003] In the chemical industry, and especially in the polymer industry, it is becoming increasingly important not only to recycle waste polymers, but also to be able to do so in a sustainable manner. Indeed, "closed-loop" recycling processes, while "closed" from a material perspective, are not truly closed in terms of the energy required (i.e., the use of fossil fuels, or ultimately the energy primarily derived from that source), especially considering the very large thermal energy required for the pyrolysis process. As a result, the carbon footprint can become so large that it undermines the effectiveness of the entire recycling loop and makes the process no longer useful.

[0004] An integrated solution such as the one proposed today would not only enable the use of "green" energy, but would also solve one of the biggest problems associated with the use of many renewable energy sources (such as solar and wind energy): their intermittency and intensity variability, which result in large temporal fluctuations in available energy power.

[0005] Many chemical processes typically require very long run times and stable process conditions to achieve consistent product quality and be economically sustainable. This is especially important for processes that require high temperatures and high flow rates, such as pyrolysis, which can take time to start, shut down, and reach stable process conditions.

[0006] Thus, the intermittency and variability of the energy source is a very significant drawback to any pyrolysis process known in the art.

[0007] Therefore, it is desirable to have a pyrolysis process that can utilize renewable energy sources, such as solar energy, while managing the intermittency and variability of the energy source, while maintaining the quality of the pyrolysis oil produced.

[0008] Several patent applications disclose processes for the thermal or catalytic decomposition of plastic materials, some of which address the potential use of solar energy.

[0009] US Patent US4415339 from the Department of Energy (DOE) teaches a method for producing a substantially hydrocarbon-free product gas (synthesis gas) from a carbonaceous feedstock using a solar reactor, where solar energy is supplied directly, i.e., through a window that allows sunlight to pass through, to heat the material for gasification.

[0010] US 4,582,590 (National Aeronautics and Space Administration) discloses a method for pyrolysis of shale which involves the use of concentrated solar radiation, which passes through a "solar window" and reaches a ceramic honeycomb receiver, which is then heated to 350°C.

[0011] WO2010 / 103520 discloses a photovoltaic device for converting sludge by pyrolysis, which includes a solar-powered pyrolysis reactor. Such solar energy is concentrated by a concentrating mirror and directed to a receiver located within the pyrolysis reactor. When a sensor detects that the solar radiation intensity falls below a threshold, the reactor is shut down.

[0012] WO2017 / 055652 (Ministry of Energy) describes a hybrid power plant based on the use of solar energy, which includes a molten salt solar receiver configured to heat molten salt with solar energy. There are cold and hot salt storage tanks, a steam generator, a condenser, and a reactor-salt-biomass exchanger for exchanging heat between the salt flow and biomass.

[0013] CN109207179 discloses a system for producing synthesis gas by concentrated solar molten salt pyrolysis of carbonaceous materials, such as rice husk, cotton, corn straw residue, and urban domestic waste, and the temperature can be higher than 800°C, for example, 1000°C.

[0014] WO2020 / 150244 (Sabic) discloses the use of renewable energy in olefin synthesis, claiming that at least one furnace is electrically heated and at least 90% of the heating is performed without burning fuel.

[0015] None of the cited patents disclose a process for treating plastic materials with a solar energy source to produce pyrolysis oil. Furthermore, in most cases, solar energy is utilized directly, for example, by directly concentrating solar radiation onto an absorbing surface located within a reactor.

[0016] Several patent applications disclose the use of molten salt as a heat transfer medium for producing synthesis gas from biomass (municipal waste, cotton and corn straw, rice husks, etc.). Biomass is chemically very different from plastic materials, and the resulting product (synthesis gas) is completely different from pyrolysis oil. Therefore, the required operating conditions, such as temperature, are significantly different (sometimes exceeding 1000°C). This process generally fails to achieve the objectives of the present invention. For example, as disclosed in the cited CN109207179, the molten salt used melts at approximately 400°C. Generally, it is unsafe to use molten salt near its melting point to avoid solidification of the salt mixture within the equipment. This means that this process cannot be used for the pyrolysis of plastics, which requires temperatures between 400°C and 520°C.

[0017] Pyrolysis of plastic materials is a highly desirable process that allows the recycling of mixed plastic waste by breaking down polymer chains into small organic molecules that can be used for polymer synthesis after appropriate purification processes. Most other recycling processes, such as so-called mechanical recycling (i.e., extruding waste plastics with virgin plastics to produce blends), require the use of very pure plastic waste (i.e., consisting only of specific polymers, such as expanded polystyrene, linear low-density polyethylene, or polyethylene terephthalate). In fact, different polymers are mutually incompatible, and as a result, blending such polymer mixtures with certain virgin polymers dramatically reduces their performance.

[0018] Other recycling processes, such as solvent dissolution and precipitation, can specifically dissolve certain plastic materials and precipitate nearly pure polymers. However, they require vast quantities of solvent, and also require the removal of insoluble plastics and the purification of the solvent from all dissolved and dispersed contaminants (short-chain molecules, inorganic additives used as fillers, etc.). Furthermore, this process is limited to certain plastics, as polyolefins, for example, are very difficult to dissolve.

[0019] Pyrolysis of plastic materials has the important advantage of being able to effectively process mixed plastic waste, even in the presence of non-plastic waste materials such as paper. Furthermore, unlike other technologies, it has the potential to recycle mixed plastic waste indefinitely. This means that there is an unlimited loop of plastic production from monomers, plastic use, post-consumer waste recovery, and then pyrolysis of the waste to produce monomers, thereby closing the loop. For this reason, such processes are sometimes referred to as "closed-loop recycling."

[0020] However, pyrolysis is a strongly endothermic process, requiring a significant amount of heat energy. Furthermore, the required pyrolysis temperatures are quite high (above 500 °C), necessitating high-quality (i.e., high-exergy) heat. As a result, energy sources available for this purpose are limited. Typically, these sources are gas heaters (burning natural gas and / or non-condensable gases produced during the pyrolysis process itself) or direct electric heating via the Joule effect. Electric energy has a high exergy content, making its use inefficient for Joule heating. Furthermore, the combustion of hydrocarbons produces large amounts of carbon dioxide (CO2), and in many countries, electric energy is generated by burning gas, oil, or carbon dioxide. Therefore, both electric energy and gas heating contribute significantly to the carbon footprint. Furthermore, due to the high temperatures, it is virtually impossible to pump heat from lower-energy sources (such as steam or geothermal energy) using heat pumps.

[0021] As a result, there is a high risk that the infinite recycling capacity of pyrolysis ("closed-loop recycling") will in practice be limited by the fact that large amounts of valuable and / or environmentally unfriendly energy sources must be used.

[0022] As previously reported, several patents have disclosed the direct application of sunlight collected and concentrated by a concentrating mirror to a receiver placed within a reaction chamber to produce syngas. However, because sunlight is an intermittent source, syngas production soon ceases when sunlight declines. These processes require high temperatures and long periods of time to stabilize, making the use of direct sunlight a significant limitation to practical application.

[0023] Energy storage means such as batteries or large tanks to contain thermal fluids such as molten salts can be used, but the cost remains very high and often requires the use of large amounts of valuable materials.

[0024] Therefore, there is a long-felt need for a process for producing pyrolysis oil from essentially plastic materials that uses renewable energy sources and can produce pyrolysis oil of consistent quality while dealing with the intermittency and variability of those energy sources. Summary of the Invention

[0025] The applicant has surprisingly discovered a process for producing at least pyrolysis oil from essential plastic materials using a variable intensity energy source, the process comprising the following steps: a) using a variable intensity energy source to heat the heat transfer fluid (THTF) to a temperature in the range of 350°C to 700°C; b) heating the pyrolysis reactor with a heated heat transfer fluid; c) feeding the essential plastic material, optionally already in a molten and / or preheated state, into said pyrolysis reactor; d) using the variable intensity energy source to bring the temperature of the material in the pyrolysis reactor (TMPR) to a temperature (TMPR) of 330°C to 650°C in the substantial absence of oxygen at a pressure between atmospheric and 20 bar(a); e) maintaining the temperature of the material in the pyrolysis reactor (TMPR) at a temperature between 330°C and 650°C for a time sufficient to produce at least one effluent in the pyrolysis reactor in a gaseous state; f) dynamically adjusting the pressure in the pyrolysis reactor at a value between atmospheric pressure and 20 bar(a) relative to a reference temperature (TREF), which is the temperature of the heated heat transfer fluid (THTF) or the temperature of the material in the pyrolysis reactor (TMPR), thereby maintaining a substantially constant composition of the pyrolysis oil produced; g) partially or totally condensing the effluent in the gaseous state to quantitatively form at least one liquid fluid comprising at least 10% by weight, relative to the weight of the essential plastic material fed, of hydrocarbons having a normal boiling point not lower than 25°C.

[0026] In other words, the present invention consists in defining an interpolation equation for the temperature-pressure relationship, in which 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), said interpolation equation being configured to produce pyrolysis oil of substantially constant composition and quality.

[0027] The process disclosed and claimed in this invention has the following advantages over processes known in the prior art: · The effects of intermittent and fluctuating energy sources, which are generally not suitable for the pyrolysis process of plastic materials; Stable quality of pyrolysis oil product: The quality of the product remains virtually unchanged even when the intensity of the energy source is changed and there is no heat storage to keep the heat transfer fluid at a constant temperature. · Resistance to changes in process temperature. Supports closed-loop recycling: The disclosed process can produce liquid hydrocarbons that, after further processing (e.g., by cracking and / or refining processes), can be used to make polymers. After use, articles made from such polymers can be fed back into the disclosed process. This process can be repeated indefinitely. As a result, plastic materials can be recycled virtually infinitely. ·GHG emission free: The heat required for the pyrolysis process is obtained without direct and / or indirect generation of harmful greenhouse gases (such as anhydrous carbon, CO2). Mixed Plastic Waste and Plasmix Support: Preferably, this process is fed from mixed plastic waste materials, requiring little or no pretreatment and eliminating the need for a single-material source, such as essentially pure polyethylene. Even more preferably, the process is fed from residual plastics after sorting and extraction of single materials already in the sorting process (especially polymers that can be reused if only lightly contaminated, such as polyethylene terephthalate (PET) and low-density polyethylene (LDPE)). Such feedstocks are sometimes referred to as "Plasmix" (from "Plastic Mix"). Essential plastic materials that can be fed to this process may also contain small 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 in a similar manner. Fouling-free: The process is free from fouling, carbon buildup and clogging, even when the essential plastic material is based on a high carbon-to-hydrogen ratio plastic such as polystyrene or an oxygen-rich polymer such as polyethylene terephthalate.

[0028] Referring to Figure 1, the present invention also discloses and claims a plant for producing at least pyrolysis oil from essential plastic materials, the plant comprising: A) a pyrolysis reactor (70) having at least one inlet through which essential plastic material is fed, an outlet through which at least one gaseous effluent is removed, and a jacket and / or coil with at least one inlet and one outlet for molten salt; B) a condenser (72) for receiving the gaseous effluent of the pyrolysis reactor; C) a solar collector and receiver assembly (61, 62), the receiver including at least one inlet and one outlet for molten salt, the solar collector configured to be capable of supplying concentrated solar radiation to the solar receiver, thereby heating the molten salt; D) a first tank ("low temperature tank", 63) fluidly connected to the molten salt outlet of the pyrolysis reactor (70) and for receiving and storing the molten salt returning from the pyrolysis reactor (A), the first tank being fluidly connected to the inlet of the solar receiver (62); E) a second tank ("hot tank", 64) fluidly connected to the outlet of the solar receiver (62) and for receiving and storing the molten salt returning from the solar collector and receiver (SCA1), the second tank being fluidly connected to the molten salt inlet of the pyrolysis reactor (70); F) A controller (23) that adjusts, via a pressure manager (22), the pressure set point of the pyrolysis reactor (24) relative to a reference temperature TREF, which is either the temperature THTF (21A) of the molten salt from the second tank ("high temperature tank", C2) or the temperature TMPR (21B) of the material in the first pyrolysis reactor (70).

[0029] definition In describing the present invention, ranges of values ​​(eg, ranges of pressure, temperature, amount, etc.) are considered to include the extreme values ​​unless otherwise specified.

[0030] In the description of the present invention, percentages are by weight (i.e., by mass) unless otherwise specified. The symbol "%" means percentage unless specified by weight (mass).

[0031] In describing the present invention, the term "comprising" also includes, in particularly restrictive cases, the meanings "consisting of" and "essentially consisting of."

[0032] In describing this invention, the term "essentially consisting of" means that a composition or formulation (1) necessarily contains the recited ingredients and (2) may contain unrecited ingredients that do not materially affect the basic and innovative properties of the composition.

[0033] In describing this invention, unless otherwise specified, the act of maintaining a parameter (e.g., pressure) within a predetermined range means that active action is taken to keep the parameter within the range, for example by ensuring that a measurement value is within the predetermined range and / or by adjusting the parameter via a feedback control system that sets the value of the parameter within the predetermined range.

[0034] In the description of the present invention, hydrocarbons having a normal boiling point of not less than 25°C means that such hydrocarbons individually have a normal boiling point as defined by IUPAC of at least 25°C (meaning equal to or greater than 25°C).

[0035] In the context of the present invention, the act of totally or partially condensing the gases leaving the pyrolysis reactor to form liquids at least containing hydrocarbons having a normal boiling point not below 25°C does not exclude that such liquids may also contain hydrocarbons and non-hydrocarbon compounds having a boiling point below 25°C.

[0036] In the context of this invention, a variable intensity energy source, or equivalently an intermittent energy source, means an energy source that by its nature is unable to provide constant power, such as solar energy, wind energy, tidal energy, etc.

[0037] In the description of the present invention, an essentially 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 essentially plastic material.

[0038] In the present description, plastic material refers to a general polymeric material that may contain other substances to improve performance and / or reduce cost, and conforms to the IUPAC definition (Pure Appl. Chem. Vol. 84, No. 2, pp. 377-410, 2012).

[0039] In the context of the present invention, the term "pyrolysis vapors" refers to the gas phase produced during the pyrolysis of essential plastic materials, for example the gaseous effluent of a pyrolysis reactor. This latter term includes not only the products of pyrolysis, but also compounds that are in a gaseous state under the pressure and temperature conditions of pyrolysis, such as nitrogen, water, or low-boiling plasticizers, which are already present in the essential plastic material being pyrolyzed or which are added to or already present in the pyrolysis reactor (for example in an inert gas). The hydrocarbon content in pyrolysis vapors is usually higher than 50 wt%.

[0040] In the context of this invention, the term "pyrolysis oil" refers to a liquid formed by partial or total condensation of pyrolysis vapors, which contains hydrocarbons with a normal boiling point below 25° C. The hydrocarbon content in pyrolysis oil is usually greater than 50 wt %.

[0041] In the context of this invention, pyrolysis residue or char means the product in the pyrolysis reactor in a liquid, solid or semi-liquid state.

[0042] In the description of the present invention, unless otherwise specified, the substantial absence of oxygen means that the oxygen (understood as molecular oxygen) in the pyrolysis vapor is less than 2% by weight, preferably less than 0.8% by weight, more preferably 20 ppm by weight to 4000 ppm by weight, relative to the total weight of the composition of the vapor.

[0043] In the context of this invention, heat transfer fluid refers to a solid, liquid, gas, 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 specially manufactured for the purpose of transferring heat and is stable (i.e., does not rapidly decompose) under the process conditions applied.

[0044] For purposes of this invention, molten salt refers to a salt that is solid at normal temperature and pressure (i.e., 25°C and 1 bar) but becomes liquid upon heating. Molten salts can include a single component (e.g., sodium nitrate only) or a mixture of salts (e.g., a mixture of sodium nitrate and potassium nitrate).

[0045] In the description of the present invention, unless otherwise specified, a parameter value at most equal to a predetermined value X means that the parameter is equal to or less than X, and a parameter value at least equal to a predetermined value X means that the parameter is equal to or greater than X.

[0046] In the description of the present invention, unless otherwise specified, the yield in the production of a product means the weight percentage of that product relative to the total amount of products obtained.

[0047] "C5-C12 wax fraction" means the sum of the masses of chemical compounds having 5 to 12 carbon atoms (including extreme values) in the wax relative to the total mass of the wax product.

[0048] "C5-C12 diesel fraction" means the sum of the masses of chemical compounds having 5 to 12 carbon atoms (including extreme values) in diesel relative to the total mass of the wax product.

[0049] "C5-C12 yield" means the sum of the "C5-C12 diesel fraction" multiplied by the "diesel fraction" and the "C5-C12 wax fraction" multiplied by the "wax fraction".

[0050] Thus, "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 essential plastic material fed to the pyrolysis reactor.

[0051] "Hydrocarbon" means a compound consisting of carbon and hydrogen atoms, thus excluding compounds containing heteroatoms (N, S, O, etc.).

[0052] "C5-C12 hydrocarbon wax fraction" means the sum of the masses of hydrocarbons having 5 to 12 carbon atoms (including extreme values) in the wax relative to the total mass of the wax product.

[0053] "C5-C12 hydrocarbon gas oil fraction" means the sum of the masses of hydrocarbons having 5 to 12 carbon atoms (including extreme values) in the gas oil relative to the total mass of the wax product.

[0054] "C5-C12 hydrocarbon yield" (or "C5-C12 hc yield") means the sum of the "C5-C12 hydrocarbon gas oil fraction" multiplied by the "gas oil fraction" and the "C5-C12 hydrocarbon wax fraction" multiplied by the "wax fraction." Thus, "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 essential plastic material fed to the pyrolysis reactor.

[0055] By "lhc fraction" is meant the ratio of C5-C12 hydrocarbon yield to C5-C12 yield. Thus, the "lhc fraction" is the proportion (percentage) of hydrocarbons in the C5-C12 cut.

[0056] Unless otherwise specified, the terms "part" and "parts" in this document mean parts by weight and parts by weight, respectively. Weight means mass, and refers to kg in the SI unit system.

[0057] Unless otherwise specified herein, the combination of an individual range from one list with another individual range derived from a second range list and relating to a different characteristic should be considered to be disclosed in this application even in the absence of an explicit indication of such a combination. [Brief explanation of the drawings]

[0058] [Figure 1] Figure 1 shows a process scheme and associated plant illustrating one embodiment of the present invention, featuring two heat transfer fluid reservoirs, a pyrolysis reactor, a solar collector assembly, and a pressure regulation system for the pyrolysis reactor. [Figure 2] Figure 2 shows a process scheme and associated plant illustrating one embodiment of the present invention, which features the same elements as Figure 1, plus several optional devices: a preheater, a second reactor, a char feeder, and a coker. [Figure 3] Figure 3 shows a process scheme and associated plant illustrating the condensation scheme for pyrolysis vapors exiting the pyrolysis reactor, characterized by the use of three condensers in series: the first condenser is cooled by a heat transfer fluid, and the third condenser is a flooded condenser. [Figure 4] FIG. 4 shows a process scheme and associated plant illustrating a scheme using weirs to supply heat transfer fluid to multiple units (preheater, pyrolysis reactor, second pyrolysis reactor) in a semi-series manner. [Figure 5]Figure 5 shows three different interpolation equations for the temperature-pressure relationship in graph form: from top to bottom, they represent a linear interpolation, a monotonically non-increasing piecewise constant function, and a generalized logistic function. DETAILED DESCRIPTION OF THE INVENTION

[0059] One embodiment of the present invention is shown in Figure 1. The scheme includes: · Pyrolysis reactor (70); a pyrolysis vapor laminar flow valve (81) that regulates the pressure in the reactor (70) by lamination of the pyrolysis vapors leaving the reactor; · Condenser for condensing pyrolysis vapors (72); · a separator (73) for separating the gas (non-condensable) and liquid phases; · Solar collectors (61) and receivers (62); · "cold" reservoir of heat transfer fluid (63); · "hot" reservoir of heat transfer fluid (64); Heat transfer fluid pumps (65), (66) for delivering the heat transfer fluid to the heating system (solar receiver) and the pyrolysis reactor (70); ·Optional bypass (B1) and (B2); · Temperature transmitters for reading the temperature of the heat transfer fluid (21); · a pressure transmitter (24) for reading the pressure of the pyrolysis reactor (70); a pressure controller (23) for adjusting the pressure in the pyrolysis reactor (70) by adjusting the opening of the pyrolysis vapor laminar flow valve (81); A pressure manager (22) that sets a pressure set point PMPR of the pyrolysis reactor (70) relative to a temperature TREF, which is either the temperature THTF of the heat transfer fluid (21A) or the temperature TMPR of the material in the (first) pyrolysis reactor (70).

[0060] In connection with the plant for producing at least pyrolysis oil from essential plastic material of the present invention: In the pyrolysis reactor (70), an outlet through which at least one gaseous effluent is removed is fluidly connected to a condenser (72) that receives the gaseous effluent of the pyrolysis reactor [(A)-(B) connection]; In the pyrolysis reactor (70), the jacket and / or coil is provided with at least one inlet and one outlet for the molten salt, said at least one inlet being fluidly connected to said second tank ("hot tank", 64) that receives and stores the molten salt returning from the solar collector and receiver [(A)-(E) connections]; In the pyrolysis reactor (70), the jacket and / or coil, which is provided with at least one inlet and one outlet for the molten salt, is fluidly connected to the first tank ("cold tank", 63) that receives and stores the molten salt returning from the pyrolysis reactor (A) [(A)-(D) connection]; · In the solar collector and receiver assembly (61, 62), the molten salt inlet is fluidly connected to a first tank ("cold tank", 63) that receives and stores the molten salt returning from the pyrolysis reactor [(C)-(D) connection]; · In the solar collector and receiver assembly (61, 62), the molten salt outlet is fluidly connected to a second tank ("hot tank", 64) that receives and stores the molten salt returning from the solar collector and receiver [(C)-(E) connection]; The pressure controller (23), which regulates the pressure of the pyrolysis reactor (24) relative to the reference temperature TREF, is electrically connected to a temperature sensor for the temperature of the molten salt THTF (21A) from the second tank ("high temperature tank", C2) or a temperature sensor for the temperature of the material TMPR 21B in the first pyrolysis reactor (70) [(A)-(F) connections].

[0061] In the context of the present invention, a fluid connection may include intervening or otherwise disposed devices such as, for example, pumps and valves.

[0062] In the context of the present invention, electrical connection includes non-mechanical and non-thermal means such as information transmission by the flow of electrons (electric current), the flow of photons (optical transmission such as via optical fiber), or electromagnetic waves (e.g., WiFi transmission).

[0063] The essential plastic material is fed (at 51) to a first pyrolysis reactor (70) which is heated by heat transfer fluid (33) from a hot reservoir (64). The heat transfer fluid (and therefore lower temperature) from the first pyrolysis reactor is transferred to a cold reservoir (63).

[0064] A solid or semisolid residue (e.g., char) is recovered ( 53 ).

[0065] In some embodiments, a portion of the liquid contained in the first pyrolysis reactor (70) can also be recovered from (53).

[0066] The effluent of the second reactor (71) is cooled and condensed by a condenser (72). The uncondensed gas is recovered at (55). The condensate forms pyrolysis oil, which is collected in a reservoir (73) and recovered at (56). Optionally, the reservoir (73) can be incorporated into the condenser (72).

[0067] Optional bypasses (B1) and (B2) are useful for replenishing the reservoirs from each other without having to go through the heating system and load (for maintenance and / or to decouple flow from heat duty).

[0068] The solar collector (61) and receiver (62) heat the heat transfer fluid (31) from the low temperature tank (63). The heat transfer fluid is transferred from the solar receiver (62) to the high temperature reservoir (64).

[0069] The temperature transmitter (21) reads the temperature of the heat transfer fluid. According to another embodiment, such a temperature transmitter can directly read the temperature of the non-vapor phase in the pyrolysis reactor (70).

[0070] A pressure transmitter (24) reads the pressure of the pyrolysis gases. Such a transmitter can be located inside the reactor or anywhere else where the pressure is substantially the same.

[0071] In Figure 1, the pressure transmitter (24) is located at the connection that transfers the pyrolysis vapors (52) produced in the pyrolysis reactor (70) to the laminar flow valve (81). This location provides a more reliable and accurate pressure reading than a location inside the reactor. In fact, boiling conditions can occur inside the reactor, and sudden pressure releases can result in foaming. Therefore, the sensor is more likely to become fouled if it is installed inside the reactor.

[0072] The pressure transmitter (24) is connected to a pressure controller (23) which adjusts the opening of the valve (81) to reach a pressure set point provided to the pressure manager (22).

[0073] The pressure manager (22) sets a pressure set point relative to the temperature measured by the transmitter (21).

[0074] Some embodiments of different possible relationships between the temperature and the pressure setpoint are given below.

[0075] Preferably, the essential plastic materials include different plastic compositions, and more preferably, the different plastic compositions include 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.

[0076] 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.

[0077] Preferably, said essentially plastic material is characterized by an H / C ratio (H / C index) equal to at least 70, preferably between 80 and 98, and even more preferably between 85 and 96.

[0078] Preferably, said essential plastic material is characterized by a carbon index equal to at least 55, preferably between 65 and 95, and even more preferably between 75 and 90.

[0079] 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 essential plastic material and is calculated by the following formula: Equation 1

[0080] TIFF2026504502000002.tif16166

[0081] The carbon index is proportional to the ratio of the total mass of carbon atoms to the total mass of all atoms present in the essential plastic material and is calculated by the following formula: Equation 2

[0082] TIFF2026504502000003.tif16162The "weight of all atoms" in the formula corresponds to the weight of the essential plastic material.

[0083] Preferably, the essentially plastic material contains at least one non-plastic material in an amount ranging from 0.01% to 10% by weight, more preferably from 0.05% to 7.5% by weight, and even more preferably from 0.2% to 5% by weight, based on the weight of the essentially plastic material. The non-plastic material preferably includes at least one of the following materials: paper, cardboard, wood, compost (as defined by IUPAC in "Terminology for Bio-Related 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.

[0084] Optionally, the essentially plastic material comprises an inorganic filler, such as, for example, silica, titanium oxide, talc, coke, graphite, carbon black, calcium carbonate, and the like.

[0085] Optionally, the essential plastic material contains brominated and chlorinated additives used to make the plastic material fire resistant or otherwise render it flame retardant, examples of which include hexabromocyclododecane, decabromodiphenyl oxide, polybrominated diphenyl ethers, and bromine-containing polymers such as brominated styrene-butadiene copolymers or brominated polystyrene.

[0086] Optionally, said essential plastic material comprises non-halogenated additives, such as compounds of phosphorus and nitrogen, used to make the plastic material fire resistant or in any way to impart flame retardancy.

[0087] Preferably, the essential plastic material is also recycled.

[0088] Preferably, the essential plastic material also comprises a halogenated component in an amount ranging from 0.01% to 10% by weight, based on the weight of the essential plastic material.

[0089] Preferably, the essential plastic material is obtained from a sorting process of plastic materials. More preferably, the essential plastic material is an essential plastic residual material, i.e., an essential plastic fraction remaining after recovering some plastics or after selectively extracting some plastics from the essential plastic material fed to the sorting process. Selective extraction consists of essentially homogeneous extraction of specific plastics (i.e., extraction as a single plastic). Typically, the sorting process allows for the extraction of a plastic stream that is substantially pure (i.e., as a single plastic) of polyethylene, polypropylene, and polyethylene terephthalate components. Therefore, in this preferred sorting, the essential plastic residual material is the material obtained after the extraction of said substantially pure plastics. This fraction is known in Italy under the term "Plas Mix" or "Plasmix," which is defined as "a heterogeneous collection of plastics contained in post-consumer packaging and not recovered as individual polymers" (Article 1 of House of Representatives Bill No. 4502 of May 18, 2017).

[0090] Another embodiment of the present invention is shown in Figure 2. This scheme includes the same elements as Figure 1, plus the following: ·Preheaters for essential plastic materials (74); · second pyrolysis reactor (71); · a char feeder (75), which is an element that allows the transfer of liquid, solid, or semi-solid material contained in the pyrolysis reactor to the coker (76); · Coker (76), an element capable of thermally treating liquid, solid, and semi-solid materials from the pyrolysis reactor at high temperatures; · Coke collector (77).

[0091] The above elements are optional and can exist individually or in any possible combination.

[0092] As already stated, in Figure 2 the reference temperature TREF is the temperature of the heat transfer fluid THTF. However, it is also part of the invention if the same embodiment depicted in Figure 2, but where TREF is the temperature of the material in the first pyrolysis reactor.

[0093] In embodiments where a second pyrolysis reactor is present, to avoid confusion, pyrolysis reactor (70) will be referred to as the first pyrolysis reactor. In all cases, unless otherwise specified (e.g., "second pyrolysis reactor"), pyrolysis reactor refers to the (first) pyrolysis reactor (70).

[0094] In particular, according to one embodiment shown in Figure 2, the essential plastic material is preheated in a preheater (74) before being fed to the pyrolysis reactor (70). When a heat transfer fluid is fed in series to the pyrolysis reactor and the preheater as shown in Figure 2, the fluid is preferably fed to the pyrolysis reactor first and then to the preheater.

[0095] According to another embodiment, always shown in FIG. 2, the liquid, solid or semi-solid material of the pyrolysis reactor is discharged by a char feed device (75).

[0096] According to another embodiment, which is always shown in Figure 2, in the second pyrolysis reactor (71), the pyrolysis gas flowing from the first pyrolysis reactor (70) is heated to a higher temperature by the heat transfer fluid (37) flowing from the high temperature reservoir (64). Thus, in the second reactor (71), the pyrolysis gas is further pyrolyzed.

[0097] The second reactor (71) may contain at least a catalyst, preferably a solid catalyst, or may contain no catalyst. If no catalyst is used, the gaseous effluent from the first pyrolysis reactor is heated in the second pyrolysis reactor at a temperature (TMSR) higher than the temperature of the material in the first pyrolysis reactor (temperature TMPR). If a catalyst is used, the gaseous effluent from the first pyrolysis reactor is optionally heated or cooled to a temperature (TMSR) different from the temperature of the material in the first pyrolysis reactor (TMPR) before passing through the catalyst. Preferably, when the gaseous effluent from the first pyrolysis reactor is heated, the temperature difference between the temperature of the gaseous effluent (TMSR) after heating and the temperature of the material in the first pyrolysis reactor (TMPR) is at least 10°C, preferably 30°C to 300°C, 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.

[0098] Thus, according to one embodiment of the present invention, in a process for producing at least pyrolysis oil from an essential plastic material, the gaseous effluent from the pyrolysis reactor is sent to a second pyrolysis reactor before condensation in step (g). If no catalyst is used, the gaseous stream is heated to a temperature (TMSR) higher than the temperature (TMPR) of the essential plastic material in step (e); alternatively, if a catalyst is used, the gaseous effluent from the pyrolysis reactor is optionally heated to a temperature higher than the temperature (TMPR) of the essential plastic material in step (e) or cooled to a temperature lower than the temperature (TMSR) and then passed through a catalyst before condensation in step (g). Preferably, if the gaseous stream is heated to a temperature higher than the temperature (TMPR), the temperature reached by the gaseous stream is at least 10°C higher than the temperature of the essential plastic material in step (e), preferably between 30°C and 300°C, more preferably between 60°C and 250°C.

[0099] According to another embodiment, the second pyrolysis reactor is operated at a temperature higher than that of the first pyrolysis reactor if no catalyst is used in the second pyrolysis reactor, or at about the same temperature or higher if a catalyst is used, with the additional proviso that the temperature is between 400°C and 650°C, preferably between 440°C and 550°C, and more preferably between 460°C and 530°C.

[0100] The residence time of the pyrolysis vapor in the second pyrolysis reactor is calculated by dividing the volume occupied by the vapor in the reactor by the volumetric flow rate, and is at least 10 seconds, preferably 30 seconds to 6 minutes, and more preferably 1 minute to 4 minutes.

[0101] 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, the relative motion being at a speed of at least 0.5 m / s, more preferably 2 to 50 m / s.

[0102] Any pyrolysis catalyst known in the art may be used, particularly those containing zeolites.

[0103] Thus, according to one embodiment of the present invention, in the process for producing at least pyrolysis oil from essential plastic materials, the second reactor contains a catalyst with which said gaseous effluent of the pyrolysis reactor is contacted.

[0104] 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 between atmospheric pressure minus 10,000 Pa and the pressure of the first pyrolysis reactor. More preferably, the second pyrolysis reactor is operated at a pressure between the pressure of the first pyrolysis reactor and a pressure 10,000 Pa lower than the pressure of the first pyrolysis reactor.

[0105] A separator (77), which may be incorporated into the coker device, allows the gas phase (53E) to be recycled to the process (e.g., the first pyrolysis reactor shown in FIG. 2), while the non-gas phase is recovered in flow (53D).

[0106] The char feed device (75) can be a pumping device that transfers solid, semi-solid, or liquid material from the pyrolysis reactor to the coker device while simultaneously providing physical separation between the two devices. Examples of such devices include gear pumps. Alternatively, the char feed device (75) can be a valve, such as a rotary valve, gate valve, or butterfly valve.

[0107] Advantageously, according to this embodiment, when the heat transfer fluid is supplied in a serial arrangement, the heat thermal fluid (37) from the high temperature reservoir is preferably delivered first to the coker device (76) and then to the pyrolysis reactor (70). Advantageously, the char supply device (75) can be heated by the heat transfer fluid coming from the heating jacket of the pyrolysis reactor (70).

[0108] In the coker (76), the material is heated to a temperature of 500°C to 1200°C, preferably 600°C to 1000°C, more preferably 700°C to 900°C for a time of at least 5 minutes, preferably 15 to 180 minutes, more preferably 30 to 120 minutes.

[0109] Therefore, according to one embodiment of the present invention, the solid, semi-solid or liquid material in the pyrolysis reactor is removed and heated to a temperature of 500°C to 1200°C, preferably 600°C to 1000°C, more preferably 700°C to 900°C for a period of at least 5 minutes, preferably 15 to 180 minutes, more preferably 30 to 120 minutes.

[0110] Any device capable of carrying out such an operation is suitable as a coker. Preferably, such a coker is a device comprising a rotating screw. More preferably, such a rotating screw is horizontal or has an inclination of up to 30° relative to the horizontal axis.

[0111] The coker can be heated by a heat transfer fluid, electrical resistance (Joule effect), or a combination thereof.

[0112] According to another embodiment of the invention, the condensed pyrolysis gas leaving the pyrolysis reactor is split into more than one unit, such as two or more units, or three or more units. According to the embodiment shown in FIG. 3, it is split into three units (72A), (72B), and (72C). More specifically, the pyrolysis gas (54) leaving the pyrolysis reactor passes through a "hot" first condenser (72A) and a first separator (73A) that separates a first condensed liquid (56A) from a first non-condensed vapor (55A). The first non-condensed vapor (55A) then passes through a lower temperature second condenser (72B) and a second separator (73B) that 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), which has an even lower temperature than the second condenser, and a third separator (73C), which separates a third condensed liquid (56C) from the third non-condensed vapor (55C).

[0113] Therefore, according to one embodiment of the present invention, the condensation of step g) is carried out in more than one condensation unit arranged in series.

[0114] Advantageously, according to this embodiment, the cooling of the first condenser (72A) is performed by the thermal fluid (33E) already used to heat the pyrolysis reactor before entering the low temperature reservoir (63). In this way, heat recovery is achieved, which reduces the overall heat load for condensing the pyrolysis oil, and at the same time, by heating the thermal fluid, reduces the heat load required for the solar collectors and receivers.

[0115] FIG. 3 also illustrates two additional modes for pressure control according to the present invention.

[0116] In particular, the pressure controller (23) can adjust the opening of the valve for the non-condensable gas stream (55) to change the pressure in the pyrolysis reactor (70). Alternatively, or in combination (the latter configuration is shown in FIG. 3), if a flooded condenser is used, the pressure controller (23) can adjust the flooding of the condenser (72C), for example, by adjusting the opening of the condensate valve from said condenser (72C), to change the pressure in the pyrolysis reactor (70). In fact, in a flooded condenser, the condensing power is essentially proportional (or at least a monotonic function) to the area of ​​the condenser not covered by condensate. This is because the boiling / condensation ("latent heat") phenomenon results in a much higher heat transfer coefficient than conduction alone. Immersing the condenser significantly reduces its power output. Because the density of the liquid phase is orders of magnitude higher than that of the gas phase, condensation reduces the pressure of the system; therefore, it is possible to regulate the pressure by exerting condensation forces.

[0117] In FIG. 3, pressure control is achieved by both adjusting the condensing power (valve 81C) and adjusting the flow rate of the non-condensable effluent (valve 81B).

[0118] Therefore, according to one embodiment of the present invention, the adjustment of the pressure in the pyrolysis reactor is carried out by adjusting the pressure drop of the pyrolysis reactor effluent in the gaseous state before condensation in step g).

[0119] According to another embodiment of the invention, the regulation of the pressure loss of the gaseous effluent is carried out by a throttling device, preferably a valve.

[0120] When more than one pressure control device is used, as shown in FIG. 3, a so-called split-range control mode can be advantageously used.

[0121] In split-range control mode, operation is performed on one device at a time. The device selection is determined by the controller's "operation point" (OP). For example, in Figure 3, if the OP value is between 0 and 50, valve 81B is kept at 0 (closed) and the valve adjusting the flooded condenser level (valve 81C) is varied. In this way, the pressure is varied by changing the condenser output. If the OP value is between 50 and 100, valve 81C is kept fully open and the opening of valve 81B is changed in steps. In this way, the pressure in the pyrolysis reactor is regulated by changing the condenser output. However, if the pressure continues to exceed the desired setpoint, the condenser is kept at maximum output and the pressure is regulated by changing the opening of valve 81B for the residual gas (non-condensable stream). Under relatively steady-state conditions, the pyrolysis process typically produces some non-condensable gas. Therefore, when adjustment is made in this mode, the OP value is maintained at 50 to 100, and the condenser is operated at maximum output while adjusting the opening of the residual gas valve.

[0122] All other ancillary and miscellaneous devices, as well as the components connecting such devices (e.g., connecting pipes), can be heated with the same heat transfer fluid used to heat the devices disclosed in this invention (pyrolysis reactor, coker, etc.).

[0123] Preferably, distribution of heat transfer fluid to such devices can be in series, parallel, or semi-series.

[0124] In the case of a series arrangement, preferably, the heat transfer fluid from the high-temperature reservoir (64) is first supplied to the device requiring a higher temperature (such as a coker) and the pyrolysis reactor, and then to other devices such as a preheater (74) or a char supply device (75). More preferably, the order is as follows: coker (76) (if present and heated by a heat transfer fluid), second pyrolysis reactor (71), first pyrolysis reactor (70), then (if present) a preheater (74), then (if present) a char supply device (75). According to a further embodiment, if the condensation is divided into two or more steps and the cooling fluid in the first condenser is the heat transfer fluid, as shown in FIG. 3, such a series arrangement also includes the first condenser, preferably the last element in the sequence.

[0125] Semi-series is a combination of series and parallel, and can obtain the advantages of both series and parallel modes.

[0126] One embodiment of the semi-series configuration is shown in FIG.

[0127] FIG. 4 shows a weir device (78) that receives heat transfer fluid from the hot reservoir (64), routes it to the second pyrolysis reactor (71), the first pyrolysis reactor (70), and the preheater (74), and finally discharges it to the cold reservoir (63). According to this embodiment, the weir device includes a first chamber into which oil from the hot reservoir is routed. This first chamber houses a first pump (66B) that routes 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, for example, a Bazin weir, ensures sufficient head (effective suction head) to avoid cavitation and gas entrainment during pumping of the heat transfer fluid to the second pyrolysis reactor (71). The weir forms a contaminant wall for the first chamber and recirculates the fluid within the chamber, ensuring uniformity of the fluid temperature within the chamber and providing high tolerance to flow rate fluctuations from the hot reservoir.

[0128] Excess heat transfer fluid overflows the weir and flows into the subsequent chamber. Similar to the first chamber, the subsequent chamber includes another pump (66B). This pump (66B) sends the heat transfer fluid to the first pyrolysis reactor (70) and collects the return. Similarly, another weir ensures that the pump (66B) sending the fluid to the reactor has sufficient NPSH to prevent gas entrainment. Excess heat transfer fluid overflows the weir and flows into the subsequent chamber. Similar to the second chamber, the third chamber includes another pump (66B). This pump (66B) sends the heat transfer fluid to the preheater (74) and collects the return. Similarly, another weir ensures that the pump (66B) sending the fluid to the preheater has sufficient NPSH to prevent gas entrainment. Finally, the final chamber includes another pump to send the heat transfer fluid to the cold reservoir (63). The starting and stopping of such a pump may be automatically controlled by a level switch so that the pump only starts when the level in the last chamber exceeds a predetermined height.

[0129] Unlike a series configuration, the weir device (78) allows each device to be supplied with a different flow rate of heat transfer fluid. Unlike a parallel configuration where all devices share the same source (hot reservoir), the weir device allows a higher temperature heat transfer fluid to be directed to devices requiring higher temperature and higher applicability (i.e., because the heat transfer fluid has a constant temperature when compared to the temperature of successive chambers).

[0130] Thus, the weir device allows for greater flexibility and effectiveness when compared to standard parallel or series configurations.

[0131] In another embodiment, such a weir device can be located within the hot reservoir itself, eliminating the need for a pump to deliver heat transfer fluid to the weir device. In another embodiment, the cold and hot reservoirs can be located in a solar field, and the pyrolysis plant can be located a distance from the solar field. In such a case, a buffer reservoir is required to avoid failure of the pyrolysis process in the event of a problem with the delivery of the heat transfer fluid.

[0132] In such cases, the weir device also acts as a buffer reservoir.

[0133] It should be understood that many other customizations of the weir device are possible, for example, more chambers can be provided to manage more devices heated by the heat transfer fluid.

[0134] Advantageously, all devices receiving heat transfer fluid are located at different elevation levels, minimizing the number of heat transfer pumps required.

[0135] More precisely, according to this embodiment, the first device receiving the heat transfer fluid from the pump (66) is placed at the highest height level, and the device receiving the heat transfer fluid leaving the first device is placed at a lower height level, so that the fluid can flow into the device by gravity, without the need for an additional pump.

[0136] This is advantageous because any moving parts that are above the hot fluid may also exhibit high melting points and may be particularly delicate, requiring special precautions for proper start-up and maintenance in case of malfunction. Furthermore, this method allows the heat transfer fluid in the device to be at atmospheric pressure, simplifying the device design and reducing the cost of the device. Last but not least, because the thermal jacket is unpressurized, accidental rupture of the thermal jacket reduces the risk of leakage and provides greater safety.

[0137] According to a preferred embodiment, both the hot and cold heat transfer fluid reservoirs are located at ground level.

[0138] The cold and hot reservoirs may optionally contain mixing means such as internal circulation pumps or agitators, e.g., anchor agitators, turbine agitators, or pitched blade impellers. Such mixing means improve temperature uniformity within the reservoirs and are particularly useful during start-up.

[0139] However, even without said mixing means, the flow of heat transfer fluid from the inlet to the outlet and natural convection contribute to some degree of internal circulation and mixing within the reservoir.

[0140] The preheater (74) can be any device capable of heating and preferably partially or totally melting the essential plastic material.

[0141] Examples of such devices include single screw extruders, twin screw extruders, or more generally screw devices having a jacket or equivalent means through which the plastic material can be delivered and through which a heat transfer fluid can flow.

[0142] Optionally, the heat transfer fluid also flows inside the screw, thereby improving the effectiveness of the device.

[0143] Preferably, such a device can be made substantially gas-tight, preventing gases within the first pyrolysis reactor (70) from exiting the pyrolysis reactor (70). One way to achieve this result is to use the same plastic melt that flows between the screw and barrel as the gas-tight means.

[0144] The preheating device may be equipped with a degassing device for discharging water vapor and other gases produced, in particular hydrogen chloride (HCl). For this purpose, it may be advantageous to supply the preheating device with additives that promote the generation of hydrochloric acid or enable its salting out, in addition to the essential plastic material. These additives are preferably compounds of Group IA and Group IIA elements. More preferably, they are oxides, hydroxides, carbonates, silicates, and aluminosilicates of Group IA and Group IIA elements. Even more preferably, they are calcium oxide, calcium hydroxide, calcium carbonate, sodium oxide, sodium hydroxide, sodium carbonate, potassium oxide, potassium hydroxide, potassium carbonate, and sodium aluminosilicate.

[0145] The preheating temperature can be 120° C. to 360° C., preferably 150° C. to 260° C., more preferably 170° C. to 230° C., and even more preferably 180° C. to 210° C. Optionally, the plastic raw material is partially or totally melted before being fed to the pyrolysis reactor.

[0146] The residence time in the preheating device is preferably less than 10 minutes, more preferably less than 2 minutes, especially less than 1 minute.

[0147] The first pyrolysis reactor (70) can be any reactor capable of receiving the essential plastic feedstock and subjecting it to pyrolysis conditions (temperature and pressure).

[0148] The first pyrolysis reactor for the pyrolysis of essential plastic material can be operated in batch mode, continuous mode, and semi-continuous mode, in which the essential plastic material is continuously fed and the evolved vapors are continuously extracted, but the solid residue is not continuously removed from the pyrolysis reactor.

[0149] The solids contained in the reactor are removed when the amount of solid residue in the reactor exceeds a predetermined threshold, or at a predetermined time interval, for example, at a frequency ranging from 2 days to 10 days.

[0150] Preferably, the reactor is operated in continuous or semi-continuous mode, more preferably in semi-continuous mode.

[0151] The pyrolysis process of the present invention is not limited to any particular type of reactor.

[0152] In particular, horizontal or vertical, stirred or unstirred reactors, kiln reactors or screw reactors can be used, fluidized bed reactors being not preferred.

[0153] Among stirred reactors, continuous stirred reactors (CSTRs) and multi-zone reactors can be used. Plug flow reactors (PFRs) can also be used, preferably stirred to facilitate heat transfer.

[0154] Among continuous stirred reactors (CSTRs), it is possible to use fully packed reactors (meaning that there is essentially no gas phase above the treated plastic melt and reaction products such as char), as well as reactors in which the gas phase is separated from the phase containing the liquid and possibly other phases such as the solid char formed, i.e., reactors in which a free surface is present.

[0155] According to a preferred embodiment, the reactor is a stirred reactor with a free surface.

[0156] According to a preferred embodiment, the reactor is substantially cylindrical and its axis is vertical.

[0157] 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 facing membrane along the inner surface of the reactor to reduce fouling; a thermowell thermocouple for more precise measurements inside the reactor; a thermocouple measuring the temperature of metal near the surface of the reactor wetted with polymer; or a non-contact measurement system such as infrared. Multiple systems can be used simultaneously to improve reliability.

[0158] Reactor elements in contact with such heat transfer fluids are separated from reactor elements in contact with process fluids (plastic inlet, liquefied plastic, char, gases produced by pyrolysis, etc.).

[0159] Preferably, the heat transfer fluid flows inside the jacket. Optionally, the heat transfer fluid also flows inside the agitator, which improves heating of the liquid mass.

[0160] Preferably, the heat transfer fluid is a molten salt. Any molten salt can be used in the present invention.

[0161] The heat transfer fluid may be low melting point alkali metals of Groups (III)A, (IV)A and (V)A (metal alloys containing elements belonging to Groups (III)A to (V)A of the periodic table), as well as Group (III)A, (IV)A and (V)A based metal alloys. Alkali metals include cesium (mp 28°C), lithium (180°C), potassium (63°C), rubidium (39°C), and sodium (mp 98°C); low-melting metals from groups (III)A, (IV)A, and (V)A include indium (mp 157°C), gallium (mp 30°C), bismuth (mp 271°C), lead (mp 327°C), and tin (mp 232°C); metal alloys based on (III)A, (IV)A, and (V)A are metal alloys containing at least 70% by weight of elements from groups (III)A through (V)A of the periodic table, 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, and 16.5% Sn, mp 62°C), rose metal (50% bismuth, 25–28% lead, 22–25% tin, mp 98°C), pewter metal (tin (85–99%), antimony (approximately 5–10%), copper (2%), bismuth, mp approximately 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), and galinstan (68.5% Ga, 21.5% In, and 10.0% Sn, mp -19°C).

[0162] Among the low melting alkali metals, sodium and potassium are preferred; among the metals of Groups (III)A, (IV)A, and (V)A, lead, bismuth, indium, gallium, and tin are preferred; among the metal alloys based on Groups (III)A, (IV)A, and (V)A, wood metal, field metal, rose metal, pewter metal, cast metal, and galinstan are preferred.

[0163] According to one embodiment, the molten salt is a molten salt of Groups IA and IIA of the periodic table, preferably sodium nitrate, sodium nitrite, potassium nitrite, potassium nitrate, lithium nitrate, calcium nitrate or mixtures thereof.

[0164] 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.

[0165] According to one embodiment, such a nitrate / nitrite mixture is a eutectic mixture of 53 wt% potassium nitrate, 40 wt% sodium nitrite, and 7 wt% sodium nitrate; or according to another embodiment, such a K / Na nitrate / nitrite mixture is a eutectic mixture of 45.5 wt% potassium nitrate and 54.5 wt% sodium nitrite.

[0166] According to one embodiment, such a nitrate / nitrite mixture is the so-called "solar salt", characterized by 60 wt% sodium nitrate and 40 wt% potassium nitrate.

[0167] According to one embodiment, such a nitrate / nitrite mixture is the so-called "Hitec XL" and is characterized by 7 wt% sodium nitrate, 45 wt% potassium nitrate, and 48 wt% calcium nitrate.

[0168] According to one embodiment, the nitrate / nitrite mixture is 100 wt% lithium nitrate.

[0169] According to one embodiment, the nitrate / nitrite mixture is 25 wt% lithium nitrate, 25 wt% sodium nitrate, and 50 wt% potassium nitrate.

[0170] According to one embodiment, the molten salt is sodium chloride and a mixture of chlorides, such as a mixture of sodium chloride and potassium chloride, optionally together with magnesium chloride.

[0171] According to a further embodiment, the heat transfer fluid is a molten salt containing a metal fluoride of Group IA or Group IIA, preferably lithium fluoride, sodium fluoride, potassium fluoride, and calcium fluoride. More preferably, the heat transfer fluid is a molten salt containing sodium nitrite, sodium nitrate, and potassium nitrate. Even more preferably, the heat transfer fluid is a molten salt containing sodium nitrate and potassium nitrate.

[0172] Preferably, the heat transfer fluid has a low melting point, more preferably at most 310°C, even 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 at least 400°C, more preferably at least 450°C, even more preferably at least 490°C, and even more preferably at least 540°C.

[0173] 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.

[0174] According to one embodiment, any component of the process intended to contain molten salt is capable of gravity drainage, e.g., reactors, cokers, preheaters, valves, etc. According to another embodiment, any component containing molten salt characterized by the presence of moving parts (e.g., valves) or large aspect ratios (e.g., pipes) is equipped with electric heat tracing that can be activated prior to start-up of the plant, thereby melting the heat transfer medium.

[0175] 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 zone that is essentially limited in size. Examples of "single focus" include parabolic dishes and power towers. According to another embodiment, the solar collector is "focal," meaning that the sun's rays are reflected into a focal zone that is essentially a line. Examples of such solar collectors include parabolic troughs and linear Fresnels.

[0176] Preferably, the solar collector is a parabolic trough or a linear Fresnel.

[0177] The solar radiation collected by such a collector is reflected onto a so-called solar receiver. In one embodiment, such a solar receiver consists of a heat exchanger in which a heat transfer fluid is heated. Typically, in such receivers, the fluid flows through tubes that are heated by the solar radiation.

[0178] In another embodiment, such a solar receiver consists of a tube through which the solar radiation is guided. The tube is usually made of metal and is called an "absorber." It is coated with a selective coating that maximizes the absorption of solar radiation while minimizing heat loss due to infrared radiation. The glass tube that encases the absorber tube is transparent, allowing sunlight to pass through. A high vacuum is created between the two tubes, limiting convective heat loss. Degassing nozzles and / or getters may be added to maintain this vacuum for long periods of time.

[0179] The ends of the solar receiver are equipped with bellows to account for the difference in thermal expansion between the glass and metal materials.

[0180] The solar collectors and associated receivers can be assembled in parallel, in series, or in a parallel and series combination, with the parallel and series combination being preferred.

[0181] The concentration ratio is the ratio of the radiant power density at the receiver to the radiant power density of the sun without concentration, and is therefore the factor by which the incident energy flux is optically enhanced at the receiving surface. The concentration ratio according to the present invention is 8 to 1000, more preferably 10 to 100, and even more preferably 15 to 80.

[0182] The hot and cold reservoirs can be any vessels that can be filled with a heat transfer fluid, such as vertical or horizontal tanks, which are advantageously insulated to limit heat loss.

[0183] According to one embodiment, the heat transfer fluid pump 66 is located within the reservoir.

[0184] According to one embodiment, the level of heat transfer fluid in the reservoir is monitored and pyrolysis duty is limited if the level of heat transfer fluid in the hot reservoir becomes too low.

[0185] According to one embodiment of the present invention, an additional reservoir of heat transfer fluid is also provided, thereby delivering heat transfer fluid to the pyrolyzer at more than two temperatures.

[0186] According to one embodiment, such first pyrolysis reactor is preferably an essentially cylindrical vertical vessel.

[0187] Preferably, the upper and lower ends of the first pyrolysis reactor are conical, elliptical or semi-elliptical, which allows for better recirculation and less observed fouling, which is in fact a major problem in pyrolysis reactors.

[0188] Preferably, the first pyrolysis reactor (70) has at least an agitator. Such an agitator should be of sufficient size to ensure that the entire reactor volume filled with liquid and solid phases is at least continuously or semi-continuously wiped (e.g., not necessarily gas phase). Preferably, the agitator should also be capable of periodically moving material near the reactor walls to clean the surfaces and reduce fouling.

[0189] Examples of such agitators include anchor or ribbon agitators, or in some cases turbine agitators.

[0190] The rotation speed of such a stirrer is usually 1 to 300 rpm, preferably 5 to 120 rpm.

[0191] According to some embodiments, more than one agitator can be used. In this case, the agitators advantageously have different agitation speeds. One simple way to achieve this is to leave one agitator free to rotate, so that it is entrained in the fluid at a rotational speed lower than that of one of the active agitators, but higher than zero.

[0192] The term "condenser" refers to any device that receives a fluid in a gaseous state and is capable of removing sufficient heat from said fluid to produce at least a portion of the fluid in a liquid state.

[0193] An example of a device is a condenser that includes a coil through which a heat transfer fluid flows, which can remove heat from the gaseous fluid being treated.

[0194] Other methods of removing heat may also be used, for example, alternatively or in combination, the condenser may be provided with a jacket through which the heat transfer fluid flows, through which heat can be removed.

[0195] Flooded condensers can also be used to advantage. In this case, the condenser is partially immersed (or flooded) by the liquid phase produced. Its condensing power is adjusted by varying the height of said liquid phase, since only the unimmersed coils can absorb heat from the vapor being condensed. This effectively allows the capacity of the condenser to be adjusted.

[0196] Alternatively, the condenser can consist of a distillation column. In this case, the condensed fluid originates from the condenser of the column, and the condensed liquid flows back through the column by gravity or by pumping, condensing the vapors in the column. This also improves the fractionation of the incoming vapors: at each stage, heavier substances are concentrated in the liquid phase and lighter substances in the vapor phase, resulting in a better separation of the condensed high-boiling components from the low-boiling components that remain in the vapor phase. Furthermore, the vapor scrubbing performed by the column allows solid particles present in the incoming vapor to be separated and recombined in the liquid phase.

[0197] The pyrolysis vapor condenser can be a single condenser or multiple condensers in series or parallel. Preferably, if more than one condenser is used, two to four condensers are used in series, more preferably three condensers are used in series.

[0198] When the condensers are in series, each condenser receives uncondensed gas from the previous condenser, with the first condenser receiving pyrolysis vapors.

[0199] In this preferred mode, the condenser receiving the pyrolysis vapors (first condenser) operates at a higher temperature than the second condenser receiving the uncondensed vapors from the first condenser. If there are more condensers, the next condenser (e.g., third condenser) receives the uncondensed vapors from the previous condenser and operates at a lower temperature.

[0200] According to a preferred method, a portion of the fluid in liquid state condensed in at least one condenser is recycled to the pyrolysis reactor. Preferably, the fluid recycled to the reactor is taken from the first condenser.

[0201] According to one embodiment, if more than one condenser is used, heat is removed by the first condenser using a heat transfer fluid, as previously described in FIG. 3 (condenser 72A).

[0202] The hydrocarbon-containing fluid that remains uncondensed after passing 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 be advantageously used as fuel gas. Part of this gas can be combusted to provide additional heat energy useful for the pyrolysis process. For this purpose, for example, a gas heater can be used to regulate the temperature of the heat transfer fluid circulating in the reactor jacket. Alternatively, this residual gas can be advantageously used to feed a refinery plant, for example a cracking plant.

[0203] According to one embodiment of the present invention, C5-C12 compounds are also contained 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 IHC fraction is at least 70%, preferably at least 85%, and more preferably 96% to 99.9%.

[0204] According to the invention, the fluid (i.e., pyrolysis oil) remaining in a liquid state after condensation in the at least one condenser is quantitatively at least 10% by mass, preferably 20% to 92% by mass, more preferably 30% to 85% by mass, and even more preferably 40% to 75% by mass, based on the mass of the essential plastic material supplied. When multiple condensers are used, this amount is calculated by adding up the masses of the liquid produced in each condenser.

[0205] According to the present invention, after condensation in the at least one condenser, at least a fluid is formed, which is in a liquid state and comprises hydrocarbons having a normal boiling point of 25°C or higher, preferably 40°C or higher, and more preferably 80°C to 220°C.

[0206] For example, the use of steam or the presence of water in the essential plastic material can result in the formation of other liquid phases (such as a water-rich aqueous phase). These other liquid phases can be separated from the hydrocarbon-rich phase by standard equipment such as a separator, or by removing them from the bottom of a condensate container (as the aqueous phase is usually heavier than the hydrocarbon-containing organic phase).

[0207] In this context, the at least one fluid comprising a hydrocarbon that is in a liquid state and has a normal boiling point of 25° C. or higher is intended to be a hydrocarbon-containing organic phase.

[0208] Preferably, at least the first pyrolysis reactor operates at atmospheric or superatmospheric pressure (i.e., a pressure greater than atmospheric pressure). According to one embodiment, the pressure is between 1.1 and 20 bara, preferably between 2 and 10 bara, more preferably between 2.1 and 6 bara.

[0209] Preferably, the temperature reached by the essential plastic material in the first pyrolysis reactor is 330°C to 580°C, more preferably 340 to 540°C, even more preferably 360 to 500°C, even more preferably 380 to 480°C, and most preferably 410 to 450°C.

[0210] According to one embodiment, the residence time of the essential plastics material in the first pyrolysis reactor is at least 20 minutes, preferably 1 hour to 15 hours, more preferably 2 hours to 8 hours. If the first pyrolysis reactor operates in batch mode, the residence time is calculated as the period during which the essential plastics material is at a temperature of at least 300°C. If the first pyrolysis reactor operates in continuous or semi-continuous mode, the residence time is calculated as the ratio of the volume of the reactor not occupied solely by the gas phase to the volumetric flow rate of the essential plastics material entering the reactor.

[0211] Heating of the essential plastic material in the pyrolysis reactor is achieved by the flow of said heat transfer fluid in the reactor, so that, when good agitation is ensured, the temperature of the mixture of liquid, solid and semi-solid materials in the pyrolysis reactor approaches the temperature of the heat transfer fluid flowing in the reactor.

[0212] According to an alternative embodiment, the temperature 21 used to control the process pressure (manager 22, controller 23) is the temperature of the non-gas phase (liquid, solid or semi-solid phase) in the pyrolysis reactor.

[0213] In fact, the pyrolysis reactor is heated by a heat transfer fluid, so the temperature of the non-gaseous phase in the pyrolysis reactor is closely related to the temperature of the heat transfer fluid.

[0214] Any technique known in the art can be used to maintain the pressure in the pyrolysis reactor at a defined value. Such maintained pressure can have different values ​​as a function of the pyrolysis temperature. According to a first method, the pressure can be maintained at a specified value by adjusting the heat extracted from a condenser located downstream of the reactor and in fluid communication with the reactor. In this mode, more heat is removed from the condenser, resulting in greater condensation of the vapor. This condensation converts the evaporated material from a gaseous state into a much denser liquid state, reducing the pressure.

[0215] Alternatively, the pressure can be controlled by introducing a gas such as nitrogen, argon, or water vapor and adjusting the flow rate of such gas with a valve. According to one embodiment, such a gas is introduced into the pyrolysis reactor and also acts as an inert gas (i.e., a gas that does not directly participate in the pyrolysis reaction and can replace the oxygen present in the reactor when the reactor is open to the atmosphere, for example, during maintenance or before start-up).

[0216] According to a preferred embodiment, the pressure can be controlled by adjusting the flow rate of the non-condensed gas stream (the gas stream of the last condenser if more than one condenser is used in series).

[0217] The heat output to the first and second pyrolysis reactors can be adjusted by controlling the flow rate of the heat transfer fluid, or its temperature, or both.

[0218] According to one embodiment, the pyrolysis of the essential plastic material of the present invention is carried out in the substantial absence of oxygen, where "substantially absent of oxygen" is defined as above. Advantageously, the pyrolysis process of the present invention produces particularly useful products, such as jet fuel or virgin naphtha, which is particularly suitable for steam cracking for the production of monomers of industrial interest, or for the synthesis of polymers.

[0219] 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, more preferably between 30°C and 300°C, and even more preferably between 60°C and 250°C.

[0220] The residence time of the pyrolysis vapor, calculated by dividing the volume occupied by the vapor in the reactor by the volumetric flow rate, is at least 20 seconds, preferably 30 seconds to 6 minutes, and more preferably 1 to 4 minutes.

[0221] Preferably, the second pyrolysis reactor is catalytic, meaning that a catalyst, preferably a solid catalyst, is present in the second pyrolysis reactor and the pyrolysis vapors come into contact with the catalyst. More preferably, the effluent in gaseous state is in relative motion with respect to the solid catalyst in contact with the effluent in gaseous state, the relative motion being at a speed of at least 10 m / s, more preferably 20-300 m / s.

[0222] Any pyrolysis catalyst known in the art can be used, including in particular zeolites.

[0223] According to one embodiment, the process of the present invention for producing at least pyrolysis oil from essential plastic material using a variable intensity energy source comprises the following steps: a) heating the heat transfer fluid to a temperature between 350°C and 700°C (THTF) using a variable intensity energy source; b) heating the first pyrolysis reactor with the heated heat transfer fluid; c) feeding the essential plastic material, optionally already in a molten and / or preheated state, into a first pyrolysis reactor; d) using the variable intensity energy source to cause the essential plastic material in the first pyrolysis reactor to reach a temperature of between 330°C and 650°C at a pressure between atmospheric and 20 bar(a) in the substantial absence of oxygen; e) maintaining the essential plastic material in the first pyrolysis reactor at a temperature of between 330°C and 650°C for a time sufficient to produce at least one effluent in a gaseous state in the first pyrolysis reactor; f) dynamically adjusting the pressure in the first pyrolysis reactor at a value between atmospheric pressure and 20 bar(a) relative to a reference temperature (TREF), which is either the temperature of the heated heat transfer fluid (THTF) or the temperature of the material in the first pyrolysis reactor (TMPR), thereby maintaining a substantially constant composition of the pyrolysis oil produced; g) partially or totally condensing the effluent in the gaseous state to quantitatively form at least one liquid fluid containing hydrocarbons having a normal boiling point of 25°C or higher, in an amount of at least 10% by weight relative to the weight of the essential plastic material fed.

[0224] In step f), "dynamically adjusting the pressure in the first pyrolysis reactor relative to the reference temperature (TREF) to maintain a substantially constant composition of the pyrolysis oil produced" means that the composition of the pyrolysis oil may vary within a certain tolerance range. The tolerance range is a value that a person skilled in the art would recognize as not affecting the functionality of the pyrolysis oil, i.e., a value that results in a yield of C5-C12 compounds in the pyrolysis oil of at least 18% and a yield of C5-C12 hydrocarbons in the pyrolysis oil of at least 15%, which are relatively preferred values.

[0225] Furthermore, "dynamically adjusting" means performing the adjustment repeatedly, not just once, as needed, and the frequency of such adjustment can be at least once every eight hours, preferably at least once every hour, and more preferably once every minute.

[0226] According to one embodiment, the variable intensity energy source is a concentrated solar power (CSP) solar energy source, photovoltaic power, wind power, tidal power, and combinations thereof. Preferably, according to one embodiment, the variable intensity energy source is photovoltaic power, a concentrated solar power (CSP) solar energy source, and more preferably a concentrated solar power (CSP) solar energy source.

[0227] According to one embodiment, there is further present a second energy source of a different type from said variable intensity energy source, and the heating in step (a) is performed by both the variable intensity energy source and said second energy source.

[0228] Preferably, the second energy source is an electricity or heat source from a fossil fuel, a biomass fuel (particularly biomethane or renewable natural gas) or a nuclear fuel, and combinations thereof.

[0229] According to one embodiment, the process for producing at least pyrolysis oil from essential plastic material according to the invention comprises the following further steps: a2) Storing the heat transfer fluid heated to temperature (THTF) in a tank.

[0230] According to one embodiment, the process disclosed in the present invention produces at least pyrolysis oil from essential plastic material, wherein the pressure regulation in step (f) relative to a reference temperature (TREF), which is either 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 values ​​correspond to a predetermined set of pressure-temperature values ​​obtained according to an interpolation method described below.

[0231] It is to be understood that according to another embodiment, the temperature used to adjust step (f) is the temperature of the liquid / solid / semi-solid mass contained within the pyrolysis reactor.

[0232] Various regulation schemes are possible. According to one embodiment of such a control scheme, the pressure regulation in step (f), which is related to a reference temperature (TREF), which is either the temperature of the heated heat transfer fluid (THTF) or the temperature of the material in the pyrolysis reactor (TMPR), is performed by the method providing for the setting of a lower temperature threshold (TTL) and an upper temperature threshold (TTU), by increasing the pressure when the temperature (TREF) decreases while the temperature (TREF) is within the lower temperature threshold (TTL) and the upper temperature threshold (TTU), and vice versa. Such pressure increase or decrease is preferably calculated according to an interpolation equation of the temperature-pressure relationship between TTL and TTU. The method further comprises maintaining the pressure constant while the temperature (TREF) is above the upper temperature threshold or below the lower temperature threshold.

[0233] According to one embodiment, the interpolation equation for the temperature-pressure relationship between TTL and TTU is a linear interpolation, i.e., in a graph of pressure (vertical axis) versus temperature (horizontal axis), the operating line is the line between points (TTL, PLU) and (TTU, PLL); therefore, according to this embodiment, the pressure set point (PMPR) for the temperature TREF between TTL and TTU is the vertical axis value of said line at a given horizontal axis value.

[0234] According to an alternative embodiment, the interpolation equation for the temperature-pressure relationship between TTL and TTU is a monotonically non-increasing piecewise linear function passing through the (TTL, PLU) and (TTU, PLL) endpoints, in particular a monotonically non-increasing piecewise constant function derived by a linear combination of at least one Heaviside (step) function, preferably 2 to 10 Heaviside (step) functions.

[0235] According to an alternative embodiment, the interpolation equation for the temperature-pressure relationship between TTL and TTU is a generalized logistic function that passes through the (TTL, PLU) and (TTU, PLL) endpoints, and is preferably a sigmoid function (also referred to as a "logistic function").

[0236] Preferably, the interpolation formula for the temperature-pressure relationship between TTL and TTU is a linear interpolation, a piecewise constant function, or a generalized logistic function, more preferably a linear interpolation or a piecewise constant function, and even more preferably a linear interpolation function.

[0237] Therefore, according to one embodiment of the present invention, the process of the present invention is characterized in that when the temperature is between the lower temperature threshold (TTL) and the upper temperature threshold (TTU), the pressure is set to a value obtained by an interpolation formula of the temperature-pressure relationship, preferably a linear interpolation, a piecewise constant function or a generalized logistic function.

[0238] The pressure is set by fixing the target pressure set point by the pressure manager (22) at a predetermined value, which allows the pressure controller (23) to regulate the pressure in the (first) pyrolysis reactor to the target value, as previously described.

[0239] According to a possible sub-scheme of control that can be used for any interpolation formula, if the temperature (TREF) is equal to or below the lower temperature threshold (TTL), the pressure is set to the upper pressure limit (PLU), and if the temperature (TREF) is equal to or above the upper temperature threshold (TTU), the pressure is set to the lower pressure limit (PLL).

[0240] In this case, the lower pressure limit (PLL) is preferably between atmospheric pressure and 3 bar(a), more preferably between atmospheric pressure and 2.1 bar(a), and even more preferably atmospheric pressure. The upper pressure limit (PLU) is 3.2 bar(a) or more, more preferably 3.5 bar(a) to 10 bar(a), and even more preferably 4 bar(a) to 6 bar(a). In this case, the lower temperature threshold limit (TTL) is preferably 350°C to 500°C, more preferably 380°C to 440°C, and even more preferably 400°C to 420°C. The upper temperature threshold limit (TTU) is 400°C to 700°C, more preferably 420°C to 480°C, and even more preferably 440°C to 460°C. As an additional condition, the upper temperature threshold limit is in each case at least 10°C, preferably at least 20°C, and even more preferably at least 40°C higher than the lower temperature threshold limit.

[0241] Variations in temperatures within a particular range are due to the fact that different plastic materials (e.g., different plastic mix compositions) require different process temperatures. For example, LDPE requires higher process temperatures than PS polymers, especially when process conditions such as residence time are equal (see, for example, Tuffi et al., Express Polymer Letters Vol. 12, No. 1 (2018) 82-99). Those skilled in the art will understand how to modify temperatures based on raw material variations (i.e., data highlighting the decomposition temperatures of various plastics are available). For example, a raw material sample of an essential plastic material is subjected to thermogravimetric analysis (TGA) at a standard rate of 10°C / min to determine the temperature corresponding to 50% weight loss. Therefore, the above ranges can be offset to obtain similar results for other compositions of plastic materials, e.g., by using the value at 50% weight loss in the TGA as the upper threshold temperature (TTU) and the same value minus 40°C as the lower threshold temperature (TTL).

[0242] Figure 5 illustrates several adjustment schemes. Three different interpolation equations are graphically illustrated: a linear relationship, a monotonically non-increasing piecewise constant function, and a generalized logistic function. For each case, a graph is shown with pyrolysis temperature on the horizontal axis and 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 pyrolysis pressure (PMPR) setpoint (set by the pressure manager 22) is kept constant at the end point (i.e., if the temperature TREF is not higher than TTL, PMPR is equal to PLU; if the temperature TREF is not lower than TTU, PMPR is equal to PLL). When the temperature TREF is within the range (TTL, TTU), the pressure setpoint PMPR is set according to the corresponding interpolation equation.

[0243] While linear interpolation has generally been shown to be effective and stable, it suffers from the drawback of constantly changing the pressure setpoint, even with very small changes in pyrolysis temperature. This can be tedious for pressure regulators that require the setpoint to remain unchanged for some time. In such cases, a piecewise constant function may be more effective. Finally, the generalized logistic function can eliminate the discontinuity of the first derivative at the end points (TTL, TTU). This is because the derivative of this function at the end points is essentially zero. Therefore, such an interpolation formula is particularly stable in PID control (23) with large derivative components.

[0244] According to one embodiment of the present invention, step (f), which comprises dynamically adjusting the pressure in relation to the temperature of the heated heat transfer fluid, is carried out with a delay of up to 120 seconds, preferably between 0.1 and 60 seconds.

[0245] Delay refers to the time delay between measuring the temperature and determining the pressure setpoint, and therefore includes the time required for the temperature measurement, any data filtering, evaluation of the pressure setpoint, and its determination. [Example]

[0246] raw materials It was deemed appropriate to use primarily virgin raw materials, which ensured a known and consistent composition and facilitated experimental reproducibility. By preparing an appropriate mixture of raw materials, it was possible to evaluate the effect of different pyrolysis conditions, eliminating the influence of variations in the composition of essential plastic material sources. Furthermore, this method allowed the preparation of an average "plus mix," i.e., a mixture representative of the residue after sorting of recycled plastic materials.

[0247] Indeed, multiple samples of the Plasmix were taken and analyzed over time, and their average composition was determined and used to prepare the mixture used in this example.

[0248] The polymer materials used were as follows:

[0249] [Table 1]

[0250] The table below shows the atomic composition (weight percent) of the materials used.

[0251] [Table 2]

[0252] The inorganic materials used were as follows:

[0253] [Table 3]

[0254] Preparation of the mixture First, a masterbatch of inorganic additives (designated MBINORG) was prepared by mixing and extruding the following composition in a twin-screw extruder:

[0255] [Table 4]

[0256] Next, the following mixture ("PYROMIX-1") was prepared by dry blending:

[0257] [Table 5]

[0258] The above compositions were prepared to mimic the typical composition of essential plastic materials as found in Plamix, and are in fact based on the average composition of several Plamix samples analyzed to evaluate the type of plastic and the various inorganic materials contained therein.

[0259] Pyrolysis equipment used in the examples The pyrolysis apparatus ("A1") used in the examples of the present invention was configured as follows: A pyrolysis reactor comprising a flange for introducing material, a dip tube for introducing inert gas (nitrogen), a nozzle for the inlet of essential plastic material, a nozzle for the outlet of pyrolysis vapors, openings (NT1, NT2, NT3) for measuring the temperature of the liquid / solid / semi-solid mass in the reactor with thermocouples (measured at three points for increased accuracy), and one nozzle for measuring pressure (NP1); · Flowmeter with fine-tuning valve for adjusting the inert gas flow rate to the reactor; A pressure transducer installed at the top of the reactor to read the pressure of the gas inside the reactor; Three thermocouples for measuring the actual temperature of the liquid / solid / semi-solid mass inside the reactor, which are installed at the bottom of the reactor; · Electric heater jacket with thermal insulation system; A reactor temperature regulation system that reads the temperature value of one of three thermocouples and feedback controls the electrical heating output, and the control parameters are appropriately adjusted to ensure high thermal stability (temperature fluctuations of less than 5°C); a condenser for condensing the vapors leaving the reactor, the condenser being maintained at -10°C by a cooling fluid flowing from a temperature-controlled cooling unit; a valve located between the reactor and the condenser for regulating the flow of gas exiting the reactor; a reactor pressure regulation system that reads the pressure value of the pressure transducer and acts on the regulation valve by feedback to ensure high pressure stability (pressure oscillations less than 50 mbar); an expandable flask gas-tightly connected to the upper outlet of the condenser for collecting the non-condensed gas fraction; a receiver gas-tightly connected to the lower outlet of the condenser and provided with a vent connected to the upper outlet of the condenser for the purpose of recovering the condensed fraction in liquid form; Nitrogen injection valve; ·An intercept valve between the outlet of the liquid product leaving the condenser and the sealing connection of the receiver; ·An intercept valve between the outlet of the gaseous product leaving the condenser and the sealed connection of the expansion flask.

[0260] The reactor is vertical and has a substantially cylindrical profile.

[0261] Pyrolysis Examples (Comparative Examples and Examples According to the Invention) Examples were prepared using PYROMIX-1, a dry blend mixture of polymer and inorganic compound.

[0262] The conditions for each example are shown in the table below.

[0263] [Table 6]

[0264] The dry blend mixture was charged into the reactor of "Apparatus 1" described above. The volume occupied in the reactor was about 1 / 3 of the geometric volume.

[0265] The valve controlling the flow rate of pyrolysis vapors exiting the reactor was manually set to full open.

[0266] Next, the fine adjustment valve of the flow meter was fully opened, and nitrogen was injected from below through the dip tube.

[0267] The gas contained in the reactor was then removed for 24 hours to ensure complete removal of oxygen.

[0268] The valves for the gaseous and liquid product outlets from the condenser were then closed, and the nitrogen supply was immediately interrupted. An expansion flask was connected to collect the produced gas, and a receiver was connected to collect the produced liquid.

[0269] The valves for the gaseous and liquid product outlets from the condenser were then reopened.

[0270] The valve controlling the flow rate of gases leaving the reactor was set to autoregulate at a value chosen for the test (P_pyro shown in the table).

[0271] Nitrogen was then injected from below through the dip tube, but the flow rate was set very low and selected so that the amount of gas collected in the inflatable balloon before replacement did not exceed 30% of the maximum balloon volume.

[0272] The thermal control system of the pyrolysis reactor was loaded with the following program: 1. First heating ramp: 4 degrees per minute, until the pyrolysis temperature T_pyro is reached; 2. Hold temperature T_pyro for 6 hours; 3. Stop heating.

[0273] The reactor's thermal control system was turned on.

[0274] Twelve hours after the end of the program, it was confirmed that the reactor temperature was below 60° C. The nitrogen supply was then interrupted, the intercept valves on the liquid and gas product outlets leaving the condenser were closed, and the reactor flange was opened.

[0275] A semi-solid material was found in the reactor (corresponding to the material that was not converted to pyrolysis vapors). This material, referred to as "char," was carefully removed from the reactor and weighed.

[0276] The reactor walls were thoroughly cleaned to remove any deposits that may have eventually formed.

[0277] The liquid contained in the liquid receiver (pyrolysis oil condensate) was weighed and then ultracentrifuged at 25,000 rpm for 45 min (Thermo Scientific Ultracentrifuge Model Sorvall Evolution RC).

[0278] After ultracentrifugation, the substance remaining at the bottom (hereinafter referred to as wax) and the supernatant (hereinafter referred to as diesel) were separated and weighed.

[0279] The fraction of diesel ("Diesel Fraction") was calculated by dividing the weight of diesel by the weight of the material initially fed to the reactor (dry blend mixture).

[0280] Similarly, the wax fraction ("wax fraction") was calculated by dividing the weight of wax by the weight of the materials initially fed to the reactor (dry blend mixture).

[0281] Similarly, the char fraction ("char fraction") was calculated by dividing the weight of the semi-solid material extracted from the reactor by the weight of the material initially fed to the reactor.

[0282] The mass of gas produced was 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 the diesel and wax). The fraction of non-condensable gas produced ("gas fraction") was calculated by dividing the mass of the gas fraction thus calculated by the weight of the material initially fed to the reactor.

[0283] Gas chromatographic analysis of diesel samples The diesel samples were characterized by gas chromatography analysis: compounds were first qualitatively identified by coupled gas chromatography-mass spectrometry (GC-MS) techniques and then quantified by gas chromatography with a flame ionization detector (GC-FID).

[0284] The following are the instrument parameters used for the GC-FID analysis: GC: Agilent HP 7890 B equipped with a Gerstel MPS autosampler Column: HP-PONA Agilent Technologies J&W-50m-0.2mm-0.5μm Carrier (H2): 1.1 mL / min constant flow Injector: 320°C, 255:1 split, 3mm (ultra-inert) glass wool liner Detector: 360℃ Oven: Column temperature program: 20°C for 5 min, 2°C / min to 70°C for 5 min, 2°C / min to 160°C for 5 min, 2°C / min to 320°C for 30 min (run time: 195 min).

[0285] Each sample was analyzed as is, assigning an arbitrary response factor of 1 equal for all compounds, and the resulting concentrations were normalized to 100%.

[0286] The obtained fractions were analyzed using the above-mentioned method, and approximately 130 compounds were identified.

[0287] The number of atoms of each element (C, N, O, H) was calculated for each of these compounds. Therefore, the mass fractions of C, N, O, and H atoms could be calculated by summing the products of the mass of each compound and the mass fraction of each atom in the compound.

[0288] Gas chromatographic analysis mode for wax samples This fraction is analyzed by various methods so that high molecular weight compounds can also be identified.

[0289] In fact, these compounds are unlikely to elute and be analyzed in gas chromatographic analysis.

[0290] Before taking samples for GPC analysis, the pyrolysis oil contained in a Schott bottle was heated to 50 °C to homogenize the contents (in some cases, a precipitate and / or layer of waxy compounds was observed at room or cooled temperatures). A few mg of sample was dissolved in 1,2,4-trichlorobenzene (Baker), 10 μL of n-heptane (internal marker) was added, and the mixture was heated to a concentration of approximately 1.8 mg / mL (dissolution at 150 °C for 1 h).

[0291] The analyses were carried out on the following chromatographic equipment: High-temperature char polymer GPC-IR Three 13 μm TSK gel HT2 columns and a pre-column bench IR5 high-temperature infrared detector provides an absorbance signal proportional to the amount of methyl and methylene groups

[0292] The experimental conditions employed were as follows: Eluent: 1,2,4TAB stabilized with BHT ·Flow rate: 1mL / min Temperature: Pump 25℃, Injector 150℃, Column 150℃, Detector 150℃ Injection volume: 200 microliters Internal standard: n-heptane

[0293] "C5-C12 wax fraction" means the sum of the masses of chemical compounds having 5 to 12 carbon atoms (inclusive) in the wax relative to the total mass of the wax product.

[0294] By "C5-C12 diesel fraction" is meant the sum of the mass of chemical compounds having 5 to 12 carbon atoms (inclusive) in the diesel relative to the total mass of said waxy product.

[0295] "C5-C12 Yield" means the "C5-C12 Light Oil Fraction" multiplied by the "Light Oil Fraction" plus the "C5-C12 Wax Fraction" multiplied by the "Wax Fraction." Therefore, "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 essential plastic material fed to the pyrolysis reactor. Since C5-C12 compounds are the most desirable compounds in closed-loop recycling of plastics, this result is the most relevant parameter.

[0296] The table below shows the C5-C12 yield, C5-C12 hc yield and lhc fraction.

[0297] [Table 7]

[0298] These parameters are very important because C5-C12 compounds are highly desirable for closed-loop recycling of plastics. Among these compounds, hydrocarbons are the most desirable because compounds containing heteroatoms (such as sulfur, oxygen, and nitrogen) must be separated in most cases to produce high-quality virgin plastics such as polyethylene, polypropylene, and polystyrene.

[0299] In Example 1 (pyrolysis at 450°C and 2.1 bar(a)), the yield of C5-C12 was very good, but when the pyrolysis temperature was reduced by 40°C (410°C and 2.1 bar(a)) at the same pressure, the yield dropped significantly.

[0300] However, when the pressure was increased to 5.1 bar(a) (Example 3), it was possible to obtain almost the same yield of the desired C5-C12 fraction, even at the same temperature (410°C) as in Comparative Example 2.

[0301] Similarly, the yield of C5-C12 hydrocarbons was very good in Example 1 (41.3%), but dropped significantly (27.7%) when the pyrolysis temperature was reduced by 40°C at the same pressure.

[0302] However, when the pressure was increased to 5.1 bar(a) (Example 3), it was possible to obtain almost the same yield (38.1%) of C5-C12 hydrocarbons, even at the same temperature as in Comparative Example 2.

[0303] Finally, the lhc fraction, the ratio of C5-C12 HC yield to C5-C12 yield, was very high (>96.5%) in Examples 1 and 3 of the present invention. This is because most of the C5-C12 compounds in the pyrolysis oil consist of hydrocarbons, with non-hydrocarbon compounds accounting for less than 5% of the total. In contrast, the hydrocarbon fraction in Comparative Example 2 was significantly lower (95.8%).

[0304] This means that a decrease in pyrolysis temperature due to a reduction in the power supplied by the intermittent or variable intensity energy source (e.g., when the sun goes down or when clouds reduce solar power) can be compensated for by increasing the process pressure.

Claims

1. 1. A process for producing at least pyrolysis oil from essential plastic material using a variable intensity energy source, said process comprising the steps of: a. heating a heat transfer fluid with a variable intensity energy source to a temperature between 350°C and 700°C (THTF); b. heating a pyrolysis reactor with the heated heat transfer fluid; c) feeding the essential plastic material, optionally already in a molten and / or preheated state, into a pyrolysis reactor; d. using the variable intensity energy source to bring the material in the pyrolysis reactor to a temperature of 330°C to 650°C (TMPR) at a pressure between atmospheric and 20 bar(a) in the substantial absence of oxygen; e. holding said material in said pyrolysis reactor at a temperature of from 330°C to 650°C (TMPR) for a time sufficient to produce at least one effluent that is in a gaseous state in said pyrolysis reactor; f. maintaining a substantially constant composition of the pyrolysis oil produced by dynamically adjusting the pressure in the pyrolysis reactor relative to a reference temperature (TREF), which is either the temperature of the heated heat transfer fluid (THTF) or the temperature of the material in the pyrolysis reactor (TMPR), at a value between atmospheric pressure and 20 bar(a); g. Partially or totally condensing the effluent in a gaseous state to form at least one liquid fluid comprising at least 10% by weight of hydrocarbons having a normal boiling point of 25° C. or higher, based on the weight of the essential plastics material fed. The process includes:

2. 2. The process for producing at least pyrolysis oil from essential plastic materials as described in claim 1, wherein the pressure adjustment in step (f) related 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. 2. The process for producing at least pyrolysis oil from essential plastic materials according to claim 1, wherein the pressure regulation in step (f) related to the reference temperature (TREF) is carried out by setting a lower temperature threshold (TTL) and an upper temperature threshold (TTU), and the pressure is increased if the reference temperature (TREF) decreases while the reference temperature (TREF) is within the lower temperature threshold (TTL) and the upper temperature threshold (TTU), and conversely, the pressure is kept constant while the reference temperature (TREF) is above the upper temperature threshold or below the lower temperature threshold.

4. 4. The process for producing at least pyrolysis oil from essential plastic materials according to claim 3, wherein the pressure is set to an upper pressure limit (PLU) when the temperature (TREF) is equal to or less than the lower temperature threshold (TTL), and the pressure is set to a lower pressure limit (PLL) when the temperature (TREF) is equal to or greater than the upper temperature threshold (TTU).

5. 5. The process for producing at least pyrolysis oil from essential plastic materials 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 more, more preferably between 3.5 bar(a) and 10 bar(a), even more preferably between 4 bar(a) and 6 bar(a).

6. 6. The process for producing at least pyrolysis oil from essential plastic materials according to any one of claims 3 to 5, characterized in that when the reference temperature (TREF) is between the lower temperature threshold (TTL) and the upper temperature threshold (TTU), the pressure is set to a value obtained by an interpolation formula of the temperature-pressure relationship, preferably the interpolation formula is a linear interpolation, a piecewise constant function or a generalized logistic function.

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

8. 8. The process for producing at least pyrolysis oil from essential plastic materials according to claim 7, wherein said variable intensity energy source is solar energy, preferably by means of concentrated solar power (CSP).

9. Additional steps below: a2. Storing the heated heat transfer fluid at a temperature (THTF) in a tank; A process for producing at least pyrolysis oil from the essential plastic material according to any one of claims 1 to 8, comprising:

10. 10. The process for producing at least pyrolysis oil from essential plastic material according to any one of claims 1 to 9, further comprising the step of heating in step (a) by means of both the variable intensity energy source and the second energy source, wherein the second energy source is present and the heating in step (a) is carried out by both the variable intensity energy source and the second energy source.

11. 11. The process for producing at least pyrolysis oil from essential plastic material as described in claim 10, wherein the second energy source is an electrical or heat source from fossil fuel, biomass fuel (such as biomethane), or nuclear fuel, and relative combinations thereof.

12. 12. A process for producing at least pyrolysis oil from essential plastic material according to any one of claims 1 to 11, wherein step (f) comprising dynamically adjusting the pressure in relation to the temperature of the heated heat transfer fluid is carried out with a delay of up to 120 seconds, preferably between 0.1 and 60 seconds.

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

14. 14. The process for producing at least pyrolysis oil from essential plastic materials according to claim 13, wherein the molten salts are from Groups IA and IIA of the periodic table, preferably sodium nitrate, sodium nitrite, potassium nitrite, potassium nitrate, lithium nitrate, calcium nitrate, and mixtures thereof.

15. 15. The process for producing at least pyrolysis oil from essential plastic materials as described in claim 14, wherein the molten salt is a mixture of 60% sodium nitrate and 40% potassium nitrate by weight; a eutectic mixture of 53% potassium nitrate, 40% sodium nitrite and 7% sodium nitrate by weight; or a eutectic mixture of 45.5% potassium nitrate and 54.5% sodium nitrite by weight.

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

17. 17. The process for producing at least pyrolysis oil from essential plastic materials according to claim 16, wherein the second reactor contains a catalyst with which the gaseous effluent of the pyrolysis reactor is contacted.

18. 18. The process for producing at least pyrolysis oil from essential plastic material according to any one of claims 1 to 17, wherein the condensation in step (g) is carried out in more than one condensation unit arranged in series.

19. 19. The process for producing at least pyrolysis oil from essential plastic materials according to any one of claims 1 to 18, wherein the adjustment of the pressure in the pyrolysis reactor is carried out by adjusting the pressure drop of the effluent of the pyrolysis reactor in a gaseous state prior to the condensation in step (g).

20. 20. A process for producing at least pyrolysis oil from essential plastic materials according to claim 19, wherein the regulation of the pressure drop of the effluent in gaseous state is carried out by a throttling device, preferably a valve.

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

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

23. A plant for producing at least pyrolysis oil from essential plastic materials, comprising: a. a pyrolysis reactor (70) having at least one inlet through which essential plastic material is fed, an outlet through which at least one gaseous effluent is removed, and a jacket and / or coil with at least one inlet and one outlet for molten salt; b. a condenser (72) for receiving the gaseous effluent from the pyrolysis reactor; c. a solar collector and receiver assembly (61, 62), the receiver including at least one inlet and one outlet for the molten salt, the solar collector configured to provide concentrated solar radiation to the solar receiver and heat the molten salt; d. a first tank ("low temperature tank", 63) fluidly connected to the molten salt outlet of the pyrolysis reactor (70) for receiving and storing the molten salt returning from the pyrolysis reactor (70), the first tank being fluidly connected to the inlet of the solar receiver (62); e. a second tank ("hot tank", 64) fluidly connected to the outlet of the solar receiver (62) for receiving and storing the molten salt returning from the solar collector and receiver (SCA1), the second tank being fluidly connected to the molten salt inlet of the pyrolysis reactor (70); f. A controller (23) that adjusts the pressure set point of the pyrolysis reactor (24) via the pressure manager (22) in relation to a reference temperature TREF, which is either the temperature THTF (21A) of the molten salt from the second tank ("high temperature tank", C2) or the temperature TMPR (21B) of the material in the first pyrolysis reactor (70). Including, plant.

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