Method for producing pyrolytic oil comprising liquid hydrocarbons from plastic material with high energy efficiency and associated plant

Abstract

A process for the sustainable production of pyrolytic oils comprising liquid hydrocarbons from plastic materials, preferably waste materials. The method is characterized by the use of solar radiation for heating a heat transfer fluid, such as a molten salt, at a plurality of temperature levels in order to use a hotter heat transfer fluid for a pyrolysis device that requires a higher temperature. The heat transfer fluid returned from the device is sent back to the respective solar radiation heater, thereby closing the loop. Thus, the method is characterized by at least two circuits having a heat transfer fluid. The plastic material enters a first pyrolysis reactor and is heated with a first hot fluid having a molten salt at a moderate temperature, and the resulting gas reaches a second pyrolysis reactor, which is also heated with a second hot fluid having a molten salt, thereby achieving a higher temperature. Particular settings of related equipment and methods that cooperatively utilize some specific characteristics of the pyrolysis process and the solar collector allow for higher available energy efficiencies to be obtained. In particular, the fact that pyrolysis according to the invention is performed in two stages: high energy, but moderate temperature, is required in the first stage. A high-temperature energy source is only required in the second stage, and the energy source needs a higher condensation coefficient; however, due to the manner in which the pyrolysis process is designed, a small amount of energy is required in this stage. This allows the yield of the process to be maximized in terms of the product obtained (the amount of pyrolysis oil per solar radiation power).

Description

TECHNICAL FIELD

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

[0002] The field of application is the pyrolysis of plastic materials in order to produce pyrolysis oil comprising hydrocarbons. After further processing, the pyrolysis oil can be converted into monomers suitable for the production of polymers, thus closing the loop.

[0003] In the chemical industry, and more specifically in polymers, it is increasingly strategic to not only recycle it, but also to do so in a sustainable way. In fact, a "closed loop" recycling process is not truly closed from the point of view of the matter, but also from the point of view of the energy required (i.e. its use of fossil fuels or energy sources that ultimately derive mainly from this source), especially considering the very large amount of thermal energy required by the pyrolysis process. Therefore, the resulting carbon footprint can be so large as to jeopardize the effectiveness of the entire recycling loop, making the process no longer convenient.

[0004] Integrated solutions, such as the one now proposed, not only allow the use of "green" energy, but also maximize its effectiveness. This efficiency improvement is significant considering the high value of the land area per unit of pyrolysis oil produced, determined by low solar irradiance and the high concentration factor required.

[0005] However, a process that allows to close the plastic cycle and therefore is highly desirable requires a large amount of thermal energy at high temperatures. Traditionally, for this purpose, the combustion of natural gas and / or electricity is used, in turn obtained to a large extent via the combustion of carbonaceous materials (gases, hydrocarbons, coal). Therefore, the carbon footprint of the process is high.

[0006] Technical solutions are known that use solar rays as energy for a gasification process (thus very similar to the pyrolysis of plastic materials). Typically, in these processes, solar rays are concentrated directly on an absorber placed in the reactor or on its outer surface. In other processes (for example the pyrolysis of biomass), a heat transfer fluid with molten salts is used, but obviously it must reach at least the maximum temperature required for pyrolysis.

[0007] Therefore, the use of solar radiation as energy can be a known solution, however the solutions disclosed so far have serious limitations, including in particular the fact that heating the fluid to the temperatures required for the pyrolysis process (or directly heating the pyrolysis reactor) requires very high temperatures, i.e. such as to require a very high concentration factor associated with a very low efficiency, related in particular to a significant increase in the emissivity of the absorber tube, where most of the radiant energy is re-emitted to the environment. This means that for a given fixed production of pyrolysis oil, a very high specular surface is used.

[0008] Therefore, a pyrolysis process that allows the use of solar energy, but limits the expansion of the radiated surface needed for a given production, is desirable. The solution of the present invention makes it possible to achieve this goal.

[0009] Several patent applications disclose methods of thermal or catalytic pyrolysis of plastic materials. Several of them relate to the possibility of using solar energy.

[0010] US 4,415,339 of the Department of Energy (DOE) teaches a process for the production of a substantially hydrocarbon-free product gas (syngas) from a carbonaceous material feed using a solar reactor, which comprises directing solar energy directly into the reactor. The solar energy is delivered directly, i.e. through a window where solar rays can pass through and heat the material so as to be vaporized.

[0011] US 4,582,590 (NASA) discloses a process for pyrolyzing phyllite, which comprises the use of concentrated solar radiation. The solar radiation passes through a “solar window” to a ceramic honeycomb receiver, which is thereby heated to 350°C.

[0012] WO 2010 / 103520 discloses a solar plant for converting sludge by pyrolysis, which comprises a pyrolysis reactor operable by solar energy. This solar energy is concentrated and redirected by focusing mirrors to a receiver located inside the pyrolysis reactor. When a sensor detects that the intensity of the sunlight radiation drops below a threshold value, the reactor is shut down.

[0013] WO 2017 / 055652 (Department of Energy) describes a hybrid plant based on the use of solar energy, which comprises a molten salt solar receiver configured to heat molten salt by solar energy. There are cold and hot salt tanks, a steam generator, a condenser, and a reactor-salt-biomass exchanger that exchanges heat between the flows of salt and biomass.

[0014] CN 109207179 discloses a syngas production system via concentrated solar molten salt pyrolysis of carbonaceous materials. The carbonaceous materials can be, for example, rice husks, cotton and corn stalk residues, and municipal solid waste, and the temperature can be higher than 800°C, for example 1000°C.

[0015] WO / 2020 / 150244 (Sabic) discloses the use of renewable energy in the synthesis of paraffin wax. In the claimed plant, at least one of the furnaces is an electric furnace, in which at least 90% of the heating is generated without burning fuel.

[0016] None of the cited patents disclose a method for treating plastic materials by using solar energy in order to produce pyrolysis oil. In addition, in most cases solar energy is used directly, for example by focusing solar radiation directly to an absorption surface located inside the reactor.

[0017] Some patent applications disclose the production of syngas from biomass (such as municipal solid waste, cotton and corn stalks, rice husks) using molten salts as heat transfer medium. Biomass is chemically very different from plastic materials, and the product (syngas) is completely different from pyrolysis oil. Therefore, the required operating conditions such as temperature are significantly different (even more than 1000°C). This method cannot perform the task of the present invention in general: for example, as disclosed in cited CN109207179, the molten salt used is molten at about 400°C. In general, the use of molten salts near their melting point is not safe in order to avoid solidification of the salt mixture in the plant, meaning that this method cannot be used for the pyrolysis of plastics requiring temperatures of 400-520°C.

[0018] The pyrolysis of plastic materials is a highly desirable method because it allows the recycling of mixed plastic waste materials by breaking the polymer chains into small organic molecules that can be used to synthesize polymers after appropriate refining methods. Most other recycling methods, such as the so-called mechanical recycling (i.e. extruding the waste plastic together with virgin plastic in order to produce a blend) require the use of very pure plastic waste (i.e. containing only a specific polymer, for example expanded polystyrene or straight-chain low-density polyethylene or polyethylene terephthalate). In fact, different polymers are not compatible with each other and therefore the blend of such a mixture of polymers with a specific virgin polymer greatly reduces its performance.

[0019] Other recycling methods, such as solvent dissolution and precipitation, can be used to specifically dissolve a specific plastic material so that almost pure polymers can be precipitated. However, a large amount of solvent is required and also the removal of the undissolved plastic, as well as the purification of the solvent from all dissolved and dispersed contaminants (such as short-chain molecules, inorganic additives used as fillers and the like) is required. In addition, this method can only be used for selected plastics, since for example dissolving polyolefins is quite difficult.

[0020] The pyrolysis of plastic materials has the key advantage that it can be effectively operated on mixed plastic waste, even in the presence of non-plastic waste materials such as paper; and, unlike other technologies, it can recycle mixed plastic waste indefinitely, with the following infinite loop: manufacturing plastic from monomers, using the plastic, collecting its waste after use, and manufacturing monomers by pyrolysis of its waste; thus closing the loop. For this reason, this process is often referred to as "closed loop recycling".

[0021] However, this is a strongly endothermic process and therefore it requires a large amount of thermal energy. In addition, because the pyrolysis temperature required is quite high (> 500°C), a high quality (i.e. high available energy) heat is required. Therefore, only a few energy sources are available for this range. Usually, this energy source is a gas heater (which burns natural gas and / or non-condensable gases produced by the pyrolysis process itself) or by direct electrical heating via the Joule effect. Electrical energy has a very high available energy content and its use by Joule heating is inconvenient. In addition, electrical energy and gas heating greatly contribute to increase the carbon footprint, because the combustion of hydrocarbons produces a large amount of carbonic anhydride (CO2) and in most countries, electrical energy is produced by gas, oil or carbon combustion. In addition, due to the higher temperature, the use of a heat pump to pump heat from a lower energy heat source (such as steam or geothermal energy) is practically not feasible.

[0022] Therefore, there is a high risk that the unlimited recycling capability of pyrolysis ("closed loop recycling") is in fact limited by the fact that a large amount of precious and / or non-environmentally friendly energy must be used.

[0023] As already reported, some patents disclose the direct use of sunlight collected and concentrated by focusing mirrors directly to a receiver located in the reactor chamber in order to produce synthesis gas. However, sunlight is an intermittent source and therefore synthesis gas production stops shortly after the sunlight decreases. Since these methods require high temperatures and a long time to stabilize, the use of direct sunlight is a serious limitation to their practical implementation.

[0024] Therefore, for a long time, there has been a need for a process for producing pyrolysis oil from substantially plastic materials, which uses a heat source with almost zero impact on CO2 production and is able to effectively use this energy source. SUMMARY

[0025] The Applicant has surprisingly found that a process for producing at least one pyrolysis oil from substantially plastic materials comprises the following steps:

[0026] a) heating a first heat transfer fluid F1 to a temperature T1 comprised between 400°C and 520°C by solar radiation;

[0027] b) heating a second heat transfer fluid F2 to a temperature T2 higher than the temperature T1 by solar radiation;

[0028] c) heating a first pyrolysis reactor R1 by heating the first heat transfer fluid F1, which is therefore cooled in operation;

[0029] d) heating a second pyrolysis reactor R2 by heating the second heat transfer fluid F2, which is therefore cooled in operation;

[0030] e) feeding at least one substantially plastic material M1 to a first pyrolysis reactor R1 ;

[0031] f) maintaining the substantially plastic material M1 in the first pyrolysis reactor for a residence time RT1 of at least 2 minutes and anyway sufficient to produce a hydrocarbon- containing fluid M2 in gaseous state;

[0032] g) feeding the hydrocarbon-containing fluid M2 in gaseous state produced in the first pyrolysis reactor R1 to a second pyrolysis reactor R2;

[0033] h) maintaining the fluid M2 in gaseous state in the second pyrolysis reactor for a residence time RT2 of at least 10 seconds;

[0034] i) condensing completely or partially the gas exiting the second pyrolysis reactor R2 so as to form at least one liquid containing hydrocarbons having a normal boiling point not lower than 25°C.

[0035] The method disclosed and claimed in the present application has the following advantages when compared to the methods known in the art:

[0036] - closed loop recycling readiness: the disclosed method is able to produce liquid hydrocarbons that, after further processing (for example by cracking and / or refining methods), can be used to produce polymers. After use, the objects made with these polymers can be fed again to the disclosed process. The process can be repeated indefinitely. Therefore, the plastic material can be virtually recycled an infinite number of times.

[0037] - no GHG emissions: the heat required by the pyrolysis method is obtained without directly and / or indirectly generating harmful greenhouse gases such as carbonic anhydride, CO2.

[0038] - efficient use of molten salt heat carrier fluid: the heat carrier fluid, preferably consisting of molten salt, is the same in the solar system and in the pyrolysis system, so that the same fluid can flow in both systems. Therefore, no expensive heat exchangers are required.

[0039] - maximization of the use of solar energy: solar energy is a precious source, especially when heat at high temperatures is required. In fact, in this case a higher concentration factor is required, which in turn means that a larger area of incoming solar radiation must be reflected to a relatively small heating area. The particular cooperative method arrangement disclosed in the present application is able to solve this very specific problem, since the solution provided is able to reduce in fact the average concentration factor required, as shown below.

[0040] - Mixed plastic waste and Plasmix preparation: Preferably, the process is fed by mixing plastic waste material, thus requiring little to no pre-treatment, and not requiring a single material source to be fed, such as substantially pure polyethylene. Even more preferably, after a single material has been selected and extracted (especially when the contamination is low, polymers such as polyethylene terephthalate (PET) and low-density polyethylene (LDPE) that can be reused as-is), the process is fed by the residual plastic. This feed is sometimes referred to as "Plasmix" (from plastic mix). The substantially plastic material that can be fed to the process can contain a minor amount of non-plastic materials, such as wood, paper, concrete, metals, and biomass. Plastics containing inorganic fillers and halogens, such as polyvinyl chloride, can also be fed and processed.

[0041] - No contamination: Even when the substantially plastic material fed is rich in high-carbon-hydrogen plastics (such as polystyrene) or oxygen-rich polymers (such as polyethylene terephthalate), the process has no contamination and carbon build-up, plugging.

[0042] The present invention also discloses and claims an apparatus for producing at least one pyrolysis oil from a substantially plastic material, the apparatus comprising:

[0043] A) a first pyrolysis reactor (70) having at least one inlet where the substantially plastic material is fed, an outlet where at least one gaseous effluent is removed, and a jacket and / or coil having at least one inlet and one outlet for a heat transfer fluid;

[0044] B) a second pyrolysis reactor (71) having at least one inlet where at least one gas stream from the first pyrolysis reactor (70) is fed, an outlet where at least one gaseous effluent is removed, and a jacket and / or coil having at least one inlet and one outlet for a heat transfer fluid;

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

[0046] D) a second solar collector assembly (62) comprising a second solar receiver, preferably consisting of a tube receiver, the second solar receiver comprising at least one inlet and one outlet for a heat transfer fluid, wherein the solar collector assembly is capable of delivering concentrated solar radiation to the second solar receiver, which in turn is configured to heat the heat transfer fluid;

[0047] E) a first tank (63, "cold tank") to collect low temperature heat transfer fluid, the first tank (63) being fluidly connected to receive heat transfer fluid from the first pyrolysis reactor (70) and to send heat transfer fluid to the first solar collector assembly (61);

[0048] F) a second tank (64, "warm tank") to collect medium temperature heat transfer fluid, the second tank (64) being fluidly connected to receive heat transfer fluid from the first solar collector assembly (61) and to send heat transfer fluid to the first pyrolysis reactor (70);

[0049] G) a third tank (65, "hot tank") to collect high temperature heat transfer fluid, the third tank (65) being fluidly connected to receive heat transfer fluid from the second solar collector assembly (62) and to send it to the second pyrolysis reactor (71);

[0050] H) a condenser (72) having at least one inlet for a hydrocarbon-containing gas stream and one outlet for a condensed liquid, the condenser (72) being capable of at least partially condensing the hydrocarbon-containing gas stream;

[0051] wherein the first solar collector (61) is fluidly connected to the first tank (63) at one end of the first solar receiver, and to the second tank (64) at the other end of the first solar receiver; and wherein the second solar collector (62) is fluidly connected to the second tank (64) at one end of the second solar receiver, and to the third tank (65) at the other end of the second solar receiver; wherein the condenser (72) is fluidly connected to the second pyrolysis reactor (71) to be capable of partially condensing pyrolysis vapors produced by the first and second pyrolysis reactors.

[0052] Definitions

[0053] In the description of the application, unless otherwise stated, range values (e.g. ranges of pressure, temperature, quantity, etc.) are to be considered to include the end point values.

[0054] In the description of the application, unless otherwise stated, percentages are by weight (i.e. by mass). Unless otherwise stated, the symbol "%" means percentage by weight (mass).

[0055] In the description of the application, the term "comprising" also includes its meaning as "consisting of" and "consisting essentially of" as specific limit cases.

[0056] In the description of the invention, the term "consisting essentially of means that the composition or formulation (i) must include the recited ingredients and (ii) is open to unrecited ingredients that do not materially affect the basic and novel characteristics of the composition.

[0057] In the description of the invention, the action of maintaining a certain parameter (e.g. pressure) within an indicated range means that the operation is actively performed to bring the parameter within the range, e.g. by checking that the measured value falls within the indicated range, and / or by adjusting the parameter via a feedback regulation system with the value of the parameter set within the indicated range.

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

[0059] In the description of the invention, plastic material means a general polymeric material that can contain other substances that improve the properties and / or reduce the cost, according to the IUPAC definition (Pure Appl. Chem. Vol. 84 n. 2, pp. 377-410, 2012).

[0060] In the description of the invention, "hydrocarbons having a normal boiling point not lower than 25°C" means that these hydrocarbons alone have a normal boiling point, as defined by IUPAC, of at least 25°C (i.e. equal to or greater than 25°C).

[0061] In the description of the invention, the action of condensing completely or partially the gas leaving the second pyrolysis reactor R2 so as to form at least one liquid containing hydrocarbons having a normal boiling point not lower than 25°C does not exclude that this liquid can also contain hydrocarbons having a boiling point lower than 25°C, and non-hydrocarbon compounds.

[0062] In the description of the invention, "pyrolysis vapours" means the gas phase produced in the pyrolysis of the substantially plastic material, such as the gaseous effluent of the first pyrolysis reactor. This latter contains pyrolysis products, and compounds that are gaseous under the pressure and temperature conditions of pyrolysis, already present in the substantially plastic material subjected to pyrolysis or added or already present in the first pyrolysis reactor (e.g. in the inertization gas), such as nitrogen, water or low-boiling plasticizers. In the pyrolysis vapours, the content of hydrocarbons is generally greater than 50 wt%.

[0063] In the description of the invention, pyrolysis oil means a liquid formed by partial or complete condensation of pyrolysis vapours, which contains hydrocarbons having a normal boiling point not lower than 25°C. In the pyrolysis oil, the content of hydrocarbons is generally greater than 50 wt%.

[0064] In the description of the invention, pyrolysis residue (or equivalently, char) means a product in liquid, solid, or liquid and solid (i.e. semi-solid) state in the first pyrolysis reactor, or in liquid and / or solid state at the temperature, pressure and composition conditions in the pyrolysis.

[0065] In the description of the invention, substantially absence of oxygen means less than 2% by weight, preferably less than 0.8% by weight, even more preferably between 20 and 4000 ppm by weight of oxygen (to be understood as molecular oxygen) in the pyrolysis vapour, relative to the total weight of the composition of the vapour.

[0066] In the description of the invention, "heat carrier fluid" means a solid, liquid, gas or multiphase fluid used to transfer heat from one system to another, especially from a heat source to other heat demands (thermal loads). Preferably, the heat carrier fluid is a fluid specifically manufactured for the purpose of transferring heat and stable (i.e. not rapidly degrading) under the process conditions employed.

[0067] In the description of the invention, the first heat carrier fluid does not need to be different in composition from the second heat carrier fluid, however preferably they have different temperatures.

[0068] In the description of the invention, "SCA" means a solar collector assembly, which assembly generally comprises a reflector (mirror, such as a Fresnel reflector, or parabolic mirror in the case of a parabolic trough), a metal support structure, a receiver tube, and optionally a tracking system including drivers, sensors, and controllers. The length of the receiver tube does not need to be equal to the length of the reflector, as multiple receiver tubes can be connected in series in order to form a longer receiver tube (so that lengths even greater than 200 m can be obtained), which in turn can receive solar radiation from multiple mirrors / reflectors in series. In addition, in order to optimize the mass flow rate of the heat carrier fluid in the receiver tube, and maximize the solar radiation, it is useful to divide the flow of heat carrier fluid to be heated in multiple absorber tubes in parallel. For this reason, in the description of the invention, the solar collector assembly generally comprises multiple mirrors / reflectors and associated absorber tubes, preferably in series, parallel combination, and series-parallel combination.

[0069] In the description of the invention, "molten salt" (or equivalently molten salt) means a salt which is solid at standard temperature and pressure but enters the liquid phase due to high temperature. The molten salt can consist of a single component (e.g. sodium nitrate alone) or a mixture of salts (e.g. a mixture of sodium nitrate and potassium nitrate).

[0070] In the description of the invention, "load device" means any device heated by the heat carrier fluid. Examples of "load devices" are the first and second pyrolysis reactors, the coker, the pre-heater.

[0071] In the description of the invention, "fluid circuit", "heat carrier fluid circuit", "hot circuit", "warm circuit" means a process in which the heat carrier fluid is substantially fully recirculated.

[0072] "Substantially fully recirculated" means that the heat carrier fluid is not produced or consumed in the process, so there is no net inlet or outlet flow; however, advantageously, the fluid can overflow or be slowly replaced, especially because it is known that most heat carrier fluids degrade over time at higher temperatures. Preferably, the substantially fully recirculated fluid has a total inlet or outlet mass flow of 1% or less, even more preferably 0.1% or less, of the recirculated mass flow.

[0073] In the description of the invention, unless otherwise specified, for a value of a parameter equal to at most a determined value X, it means that the parameter is equal to X or less than X; and for a value of a parameter equal to at least a certain value X, it means that the parameter is equal to X or greater than X.

[0074] In the description of the invention, unless otherwise specified, the yield in the production of a product, means the weight percentage of this product, relative to the sum of the products obtained.

[0075] Unless otherwise specified, in this document "part" and "parts" mean part by weight and parts by weight, respectively. Weight means mass, i.e. kg in SI units.

[0076] Unless otherwise specified, in this document the combination of a single range from one list with another single range from a second list of ranges and relating to a different feature should be considered as being disclosed in the application even in the absence of an explicit indication of this combination. BRIEF DESCRIPTION OF DRAWINGS

[0077] Figure 1 A method flow illustrating an embodiment of the invention is shown, characterized by three heat carrier fluid reservoirs and two pyrolysis reactors.

[0078] Figure 2 A method flow illustrating an embodiment of the invention is shown, characterized by the addition of a plastic preheater, such as an extruder or screw device.

[0079] Figure 3 A method flow illustrating an embodiment of the invention is shown, characterized by the addition of an additional device ("coker") that further processes the liquid / solid / solid residue (char) effluent of the reactor.

[0080] Figure 4A process flow illustrating an embodiment of the present invention is shown, characterized by the presence of a coker, which further processes the liquid / solid / semi-solid residue (char) effluent, and a plastic pre-heater, such as an extruder or screw device.

[0081] Figure 5 A process flow illustrating an embodiment of the present invention is shown, characterized by the fact that condensation of the pyrolysis gas is performed in more than one unit, and wherein in the first of these units the pyrolysis gas is cooled by a heat carrier fluid, then into a cold reservoir, whereby heat recovery is achieved.

[0082] Figure 6 A process flow illustrating an embodiment of the present invention is shown, characterized by the fact that the heat carrier fluid from the warm reservoir is delivered to the first pyrolysis reactor and pre-heater device in semi-series, by weir device 78, then back to the cold reservoir.

[0083] Figure 7 A process flow illustrating an embodiment of the present invention is shown, characterized by the fact that the heat carrier fluid from the warm reservoir is delivered to the first pyrolysis reactor and pre-heater device in semi-series, by weir device 78, then back to the cold reservoir.

[0084] Figure 8 A process flow is shown with a double heat carrier fluid circuit corresponding to Example 1 (the invention).

[0085] Figure 9 A process flow is shown with a single heat carrier fluid circuit corresponding to Example 2 (comparative).

[0086] Figure 10 A process flow illustrating an embodiment of the present invention is shown, characterized by the fact that the first heat carrier fluid and associated heat carrier fluid circuit are not in fluid communication with the second heat carrier fluid and associated heat transfer circuit.

[0087] Figure 11 A process flow illustrating some embodiments of the present invention is shown, characterized by the fact that it shows the location of the additional power source in three different locations (66A parallel, 66B and 66C in series).

[0088] Figure 12 A process flow illustrating an embodiment of the present invention is shown, characterized by the use of three reservoirs, and focusing on showing the hot circuit and the warm circuit and their differences.

[0089] Figure 13A method flow illustrating an embodiment of the application is shown, which is characterized by the use of four tanks and two completely independent circuits, highlighting the hot circuit and the warm circuit and their differences.

[0090] Figure 14 A method flow illustrating an embodiment of the application is shown, which is characterized by three tanks and two completely independent or partially independent circuits. DETAILED DESCRIPTION

[0091] According to one embodiment, the method for producing at least one pyrolysis oil from a substantially plastic material is characterized by the fact that the fluids F1 and F2 are substantially completely recirculated.

[0092] A first embodiment of the application is shown in Figure 1 The flow comprises:

[0093] - a first pyrolysis reactor (70) (at lower temperature), also called primary pyrolysis reactor;

[0094] - a second pyrolysis reactor (71) (at higher temperature), also called secondary pyrolysis reactor;

[0095] - a condenser (72) which condenses the effluent of the second pyrolysis reactor (71);

[0096] - a separator (73) which separates the gas (non-condensed) phase from the liquid phase;

[0097] - a medium temperature solar collector assembly or first solar collector (61) (SCA);

[0098] - a high temperature solar collector assembly or second solar collector (62) (SCA);

[0099] - a cold tank of heat transfer fluid (63);

[0100] - a warm tank of heat transfer fluid (64);

[0101] - a hot tank of heat transfer fluid (65);

[0102] - a heat transfer fluid pump (66) which delivers the heat transfer fluid to the heating system (solar receiver) and to the load (pyrolysis reactor);

[0103] - optional bypasses (B1) to (B4).

[0104] As regards the apparatus for producing at least one pyrolysis oil from a substantially plastic material, the following operations are preferably performed:

[0105] • in the first solar collector assembly (61) comprising the first solar receiver, the first heat transfer fluid Fl is heated by solar radiation to a temperature Tl comprised between 400°C and 520°C (method step a);

[0106] • in the second solar collector assembly (62) comprising the second solar receiver, the second heat transfer fluid F2 is heated by solar radiation to a temperature T2 higher than the temperature Tl (method step b);

[0107] • the jacket and / or coil is provided with at least one inlet and one outlet for molten salt comprised in the first pyrolysis reactor (70) (element "A") and the heating of the first pyrolysis reactor (70) (or Rl) is performed by heating the first heat transfer fluid Fl;

[0108] • the jacket and / or coil is provided with at least one inlet and one outlet for molten salt comprised in the second pyrolysis reactor (71) (element "B") and the heating of the second pyrolysis reactor (71) (or R2) is performed by heating the second heat transfer fluid F2;

[0109] • at least one substantially plastic material Ml is fed in the first pyrolysis reactor (70) (element "A") (method step e) and the substantially plastic material Ml is kept in the first pyrolysis reactor for a residence time of at least 2 minutes and anyway sufficient to produce a hydrocarbon- containing fluid M2 in gas state (method step f);

[0110] • the hydrocarbon-containing fluid M2 in gas state produced in the first pyrolysis reactor (70) (or Rl) is fed in the second pyrolysis reactor (71) (element "B") (method step g) and the fluid M2 in gas state is kept in the second pyrolysis reactor (71) (or R2) for a residence time of at least 10 seconds (method step h);

[0111] • the gas exiting the second pyrolysis reactor (71) (or R2) is condensed in the condenser (72) (element "H") so as to form at least one liquid containing hydrocarbons having a normal boiling point not lower than 25°C (method step i).

[0112] • In the context of the present application, a fluid connection can comprise a device interposed or positioned in any way between, for example, a pump and a valve.

[0113] In the context of the present application, an electronic connection comprises any non-mechanical and non-thermal means of transmitting information, such as a flow of electrons (electric current) or a flow of photons (optical transmission, such as through an optical fiber) or electromagnetic waves (for example, WiFi transmission).

[0114] The essentially plastic material is fed at (51) to a first pyrolysis reactor (70) which is heated by a medium temperature heat carrier fluid (33) coming from a warm reservoir (64). The heat carrier fluid coming from the first pyrolysis reactor (70) (thus at a lower temperature) reaches a cold reservoir (63).

[0115] The pyrolysis gas produced in the reactor (70) is delivered to a second pyrolysis reactor (71) at a higher temperature than the first pyrolysis reactor (70), while the solid or semi-solid residue (such as char) is recovered at (53).

[0116] In some embodiments, a portion of the liquid contained in the reactor (70) can also be recovered from (53).

[0117] In the second pyrolysis reactor (71), the pyrolysis gas from the first reactor (70) is further heated to a higher temperature by a heat carrier fluid (37) coming from a hot reservoir (65). In the second reactor (71), the gas is thus further pyrolyzed. The effluent of the second reactor (71) is cooled and condensed by a condenser (72). The non-condensed gas is recovered at (55). The condensate forms a pyrolysis oil which is collected in a reservoir (73) and recovered at (56). The reservoir (73) can be integrated in the condenser (72). The heat carrier fluid exiting the second pyrolysis reactor reaches the warm reservoir (64).

[0118] Optional bypasses (B1) to (B4) can be used to refill reservoirs one after the other without going through the heating system and the load (for maintenance and / or to separate the flow rate from the thermal load).

[0119] A medium temperature solar collector assembly (SCA) (61) heats the heat carrier fluid (31) coming from the cold reservoir (63), while a high temperature solar collector assembly (62) heats the heat carrier fluid (35) coming from the warm reservoir (64). From the medium temperature solar collector assembly (61), the heat carrier fluid reaches the warm reservoir (64), while from the high temperature solar collector assembly (62), the heat carrier fluid reaches the hot reservoir (65).

[0120] According to a preferred embodiment, the heat carrier fluid in one loop is heated by at least one solar collector assembly and cooled in at least one pyrolysis reactor, releasing its heat, before going back to the solar collector assembly (possibly through a heat carrier fluid reservoir).

[0121] According to a preferred embodiment, in the process for producing at least one pyrolysis oil from essentially plastic material, the fluids F1 and F2 are essentially completely recirculated.

[0122] Preferably, the method of the present application is a dual loop method (or alternatively, "two loop method").

[0123] This means that there are two substantially independent thermal loops: in the so-called "warm temperature thermal loop" (or more simply, "warm loop"), heat transfer fluid Fl is heated from low temperature to "warm" temperature by a first (lower temperature) solar collector assembly. This fluid is used in the first pyrolysis reactor and optionally other devices as taught in the disclosure of the present application.

[0124] In the so-called "hot temperature thermal loop" ("hot loop"), heat transfer fluid F2 is heated from "warm" temperature to "hot" temperature by a second solar collector assembly. This fluid is used in the second pyrolysis reactor and optionally other devices as taught in the disclosure of the present application.

[0125] According to one preferred embodiment, the recirculating fluid Fl forms a first heat transfer fluid loop ("warm loop") and the recirculating fluid F2 forms a second heat transfer fluid loop ("hot loop").

[0126] In the dual loop method, it is possible that the molten salt fluids of both loops are mixed at some point (typically, in the warm reservoir). However, the essential feature that makes the dual loop method distinct from the single loop method is that the heat transfer fluids are at least partially taken from at least two points of solar collector assemblies (Fl, F2) at different temperatures (Tl, T2) and are at least partially used separately to heat pyrolysis devices (such as reactors) at different temperatures.

[0127] "Used at least partially separately" means that there are at least two different lines ("hot loop", "warm loop") in which the heat transfer fluids flow and in which the load devices (such as pyrolysis reactors) are fluidly connected.

[0128] According to one embodiment, the first heat transfer fluid Fl and the second heat transfer fluid F2 have the same composition but at different temperatures. According to one embodiment, fluids Fl and F2 can be mixed at some point, preferably when they have substantially the same temperature.

[0129] According to one embodiment, the first heat transfer fluid Fl and the second heat transfer fluid F2 have the same composition but at different operating temperatures (Tl and T2) and are mixed at a single point, preferably in a reservoir (such as "warm reservoir").

[0130] A simplified view of this embodiment is shown in Figure 12 The figure is provided in order to explicitly show the flow of heat transfer fluids in each loop. In Figure 12In this case, it is found that in the "warm" tank (64), the two circuits mix together, however the two circuits remain substantially distinct as there is only one point of contact. In Figure 12 In this case, the dotted boxes are placed around the coker (76) and the preheater (74) in order to show that they are optional. The dashed lines in the tanks show the direction of flow inside the tanks.

[0131] The cold, hot and warm tanks can optionally comprise some mixing features, such as internal recirculation pumps, or agitators, for example anchor agitators, turbine agitators, or pitched blade impellers. Such mixing means improve the homogenization of the temperature in the tank, and can be particularly useful especially at start-up.

[0132] However, even in the absence of such mixing features, the flow of the heat transfer fluid from the inlet to the outlet and the natural convection contribute to some degree of internal recirculation and mixing in the tank. Thus, the dashed lines in the tanks are a symbolic representation of the direction of flow of the heat transfer fluid inside the tank, but they should not be construed as the only flow that can occur inside the tank.

[0133] Thus, with reference to the steps of the process of the application already disclosed, the subject of the application is a process for producing at least one pyrolysis oil from a substantially plastic material, wherein a first circuit comprises the step a) and the step c) and a second circuit comprises the steps b) and d).

[0134] According to another embodiment, the process for producing at least one pyrolysis oil from a substantially plastic material additionally comprises the following steps:

[0135] j) storing the first heat transfer fluid Fl from step c) in a tank ("cold tank") before it is used in step a);

[0136] k) storing the second heat transfer fluid F2 heated in step b) in a tank ("hot tank") before it is used in step d).

[0137] According to another embodiment, in the process for producing at least one pyrolysis oil from a substantially plastic material, the heat transfer fluid Fl is identical in composition to the heat transfer fluid F2.

[0138] When the fluids Fl and F2 are identical in composition, according to another embodiment, the process of the application for producing at least one pyrolysis oil from a substantially plastic material additionally comprises the following step:

[0139] l) storing the first heat transfer fluid Fl heated in step a) before it is used in step c), and the second heat transfer fluid F2 cooled in step d) before it is used in step b), in a tank ("warm tank").

[0140] Another embodiment of the present invention with "separate circuits" is shown in Figure 10 The process comprises the same devices as Figure 1 except for the warm reservoir 64, which is divided into two separate reservoirs 64A and 64B:

[0141] - The first "warm" reservoir ("warm reservoir A", 64A) collects the heat carrier fluid from the first solar collector assembly (61).

[0142] - The first "warm" reservoir (64A) delivers the heat carrier fluid to pyrolysis devices that require lower temperatures, such as the first pyrolysis reactor (70) and optionally a pre-heater or heat exchanger with an organic heat carrier fluid.

[0143] - The second "warm" reservoir ("warm reservoir B", 64B) collects the heat carrier fluid from devices that require higher temperatures, such as the second pyrolysis reactor or coker.

[0144] - The second "warm" reservoir (64B) delivers the heat carrier fluid to the second solar collector assembly (62).

[0145] A simplified view of the same embodiment is shown in Figure 13 , this figure is provided in order to clearly show the flow of heat carrier fluid in each circuit.

[0146] An embodiment of the present invention is therefore a process for producing at least one pyrolysis oil from a substantially plastic material, which process additionally comprises the following steps:

[0147] m) storing the first heat carrier fluid Fl, which is heated in step a), in a reservoir ("warm reservoir A") before it is used in step c);

[0148] n) storing the second heat carrier fluid F2, which is cooled in step d), in a reservoir ("warm reservoir B") before it is used in step b).

[0149] According to this embodiment with separate circuits, the heat carrier fluid circuits can be completely separated, so that different fluids for the hot circuit and the warm circuit can be used. For example, a molten salt with a lower melting temperature can be used for this circuit. The use of a low-melting molten salt is generally advantageous because it means that the equipment can be operated safely at lower temperatures (generally, it is appropriate for the equipment to be operated so that the molten salt has a temperature of at least 50°C above its melting point at the coldest point) and because it takes less time to restart after a long stoppage.

[0150] However, molten salts with a lower melting point also generally have a lower thermal stability, so they cannot be used for the hot circuit, which requires very high temperatures.

[0151] According to this embodiment, it is thus advantageous to use a heat carrier fluid for the warm circuit which is different from the heat carrier fluid of the hot circuit. According to this embodiment, it is preferred that the heat carrier fluid of the warm circuit has a lower melting point than the heat carrier fluid of the hot circuit, preferably the heat carrier fluid of the warm circuit has a melting point of at most 180°C, even more preferably at most 150°C.

[0152] For example, a so-called Hitec molten salt (sodium nitrate 7 wt%, potassium nitrate 53 wt%, sodium nitrite 40 wt%) or a ternary mixture of lithium nitrate, sodium nitrate and potassium nitrate, for example a eutectic mixture having the composition 25.9 wt% lithium nitrate + 20.6 wt% sodium nitrate + 54.1 wt% potassium nitrate, can be used as heat carrier fluid.

[0153] For example, a quaternary mixture of sodium nitrate, potassium nitrate, lithium nitrate and calcium nitrate, for example a mixture consisting of 9.5 mol% sodium nitrate, 52.8 mol% potassium nitrate, 27.6 mol% lithium nitrate and 10.1 mol% calcium nitrate, having a melting point of only 98.3°C, can be used.

[0154] Another embodiment of the present application with "separate circuits" is shown in Figure 14 According to this embodiment, the warm reservoir (64) is divided into two reservoirs (64A) and (64B), as according to the embodiment of Figure 13 , however the two reservoirs (64A) and (64B) are inside the same vessel, such as a tank, and separated by a weir (64C). In this way, the number of units to be established can be reduced, thereby reducing the installation costs. In addition, if the level becomes too high, the weir (64C) allows one heat carrier fluid to spill over into the other reservoir.

[0155] Optionally, the weir (64C) comprises at least one opening (64D), preferably at the bottom of the weir, which opening allows to balance the level of the two reservoirs (64A) and (64B). When this at least one opening is present, the separation of the fluids in the two reservoirs (64A) and (64B) is not complete. Thus, when the opening is large, Figure 14 the flow in corresponds to the flow in Figure 12 , as the contact surface where the fluids of the two reservoirs are in contact is large. Conversely, when the opening is small, Figure 14 the flow in corresponds to the flow in Figure 13 , as the contact surface is minimal, or even zero.

[0156] According to another embodiment, in the process the weir comprises at least one opening allowing the fluid in the warm reservoir A to flow in the warm reservoir B and vice versa.

[0157] Preferably, the substantially plastic material comprises a composition of different plastics. More preferably, the composition of different plastics comprises at least polymers with a high H / C ratio (such as for example polyethylene, polypropylene, polyurethane, polymethyl methacrylate) and polymers with a low H / C ratio (such as polystyrene, polycarbonate, polyethylene terephthalate).

[0158] Alternatively or in combination, the composition of different plastics comprises 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).

[0159] Preferably, the substantially plastic material is characterized by a H / C ratio (H / C index) equal to at least 70, preferably between 80 and 98, more preferably between 85 and 96.

[0160] Preferably, the substantially plastic material is characterized by a carbon index equal to at least 55, preferably between 65 and 95, more preferably between 75 and 90.

[0161] The H / C index is proportional to the ratio between the total mass of hydrogen atoms and the total mass of carbon atoms present in the substantially plastic material and is calculated using the following formula:

[0162]

[0163] The carbon index is proportional to the ratio between the total mass of carbon atoms and the total mass of all atoms present in the substantially plastic material and is calculated using the following formula:

[0164]

[0165] where "total atomic weight" corresponds to the weight of the substantially plastic material.

[0166] Preferably, the substantially plastic material contains at least one non-plastic material in an amount ranging from 0.01 wt% to 10 wt%, preferably in an amount ranging from 0.05% to 7.5%, even more preferably in an amount ranging from 0.2% to 5%, relative to the weight of the substantially plastic material. The non-plastic material preferably comprises at least one of the following materials: paper, cardboard, wood, compost (as defined by IUPAC in "Terminology for biorelated polymers and applications (IUPAC Recommendations 2012)", Pure Appl. Chem., Vol 84, No 2, pp. 377-410, 2012, DOI 10.1351 / PAC-REC-10-12-04), metallic materials (such as aluminium and iron), and / or inert materials.

[0167] Optionally, the substantially plastic material contains inorganic fillers such as, for example, silica, titanium oxide, talc, coke, graphite, carbon black, calcium carbonate.

[0168] Optionally, the substantially plastic material contains brominated and chlorinated additives for making the plastic material fireproof or in any case imparting flame propagation retarding properties. Examples of such additives are hexabromocyclododecane, decabromodiphenyloxide, polybromodiphenyl ether, and bromine-containing polymers such as brominated styrene-butadiene copolymers or brominated polystyrene.

[0169] Optionally, the substantially plastic material contains non-halogenated additives for making the plastic material fireproof or in any case imparting flame propagation retarding properties, such as phosphorus compounds and nitrogen compounds.

[0170] Preferably, the substantially plastic material is a recycled material, such as a waste material or a secondary virgin material.

[0171] Preferably, the substantially plastic material also contains halogen (typically polyvinyl chloride) in an amount ranging from 0.01 wt% to 10 wt%, relative to the weight of the substantially plastic material.

[0172] Preferably, the substantially plastic material is obtained from a plastic material sorting process. More preferably, the substantially plastic material is a substantially plastic material residual material, i.e. a substantially plastic material fraction that remains after some plastics have been recovered, or selectively extracted from the substantially plastic material fed to the selection process. The selective extraction consists in the extraction of substantially homogenous material of certain plastics (i.e. as single plastics). Typically, in the selection process (sorting), a flow of substantially pure plastics (i.e. as single plastics) of polyethylene, polypropylene and polyethylene terephthalate components can be extracted. Thus, in this preferred selection, the substantially plastic material residual material is the material resulting after the extraction of the substantially pure plastics. This fraction is known in Italy with the term "Plas Mix" or "Plasmix", defined as "collection of heterogeneous plastics contained in post-consumer packaging and not recovered as individual polymers" (art. 1 of the Bill no. 4502 of the Chamber of Deputies of 18 / 05 / 2017).

[0173] According to Figure 2 According to another embodiment of the application illustrated in

[0174] According to another embodiment of the application illustrated in Figure 3 According to another embodiment of the application illustrated in Figure 3 According to another embodiment of the application illustrated in

[0175] The char feeder device (75) can be a pumping device that moves the solid, semi-solid or liquid material from the first pyrolysis reactor to the coker device, while allowing a physical separation between the two devices. An example of such a device is a gear pump. Alternatively, the char feeder device (75) can be a valve, such as a rotary valve, a gate valve or a butterfly valve.

[0176] Advantageously, according to this embodiment, the high temperature hot fluid from the hot reservoir (37) is first delivered to the coker device (76) and then at (53B) to the second pyrolysis reactor (71) and then back to the warm reservoir (38). Advantageously, the char feeder device (75) can be heated by the heating jacketed fluid (34A) leaving the first pyrolysis reactor (70) and then back to the cold reservoir.

[0177] According to Figure 4 Another embodiment of the application is illustrated in the figure below, Figure 2 and Figure 3 The two embodiments illustrated are combined together. Thus, the substantially plastic material is preheated in the preheater (74) and the solid, semi-solid or liquid material from the first pyrolysis reactor (70) is delivered to the "coker" (76) by the char feeder device (75). Advantageously, the heating of this device is performed by the heating jacketed fluid from the hot reservoir and the warm reservoir, as previously described in the explanation of the embodiment of the application in Figure 2 and Figure 3 The two embodiments illustrated are combined together. Thus, the substantially plastic material is preheated in the preheater (74) and the solid, semi-solid or liquid material from the first pyrolysis reactor (70) is delivered to the "coker" (76) by the char feeder device (75). Advantageously, the heating of this device is performed by the heating jacketed fluid from the hot reservoir and the warm reservoir, as previously described in the explanation of the embodiment of the application in

[0178] 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 period of at least 5 minutes, preferably between 15 and 180 minutes, more preferably between 30 and 120 minutes. As a result of this thermal treatment, the char is purified, in particular the more volatile components are separated and collected in the gas phase, and the char is further pyrolyzed, producing a solid product with a lower H / C ratio and a higher carbon index, and with a better health safety environment (HSE) profile.

[0179] As coker, any device that can perform this operation is suitable. Preferably, this coker is a device comprising a rotating screw. More preferably, this rotating screw is horizontal or has an inclination of at most 30° with respect to the horizontal axis.

[0180] The coker can be heated by a heating jacketed fluid, and optionally by a gas heater, by electrical resistance (Joule effect), or a combination thereof. If a heating jacketed fluid is used, it is preferable to use the heating jacketed fluid from the hot reservoir.

[0181] Thus, according to one embodiment of the application, the method for producing at least one pyrolysis oil from a substantially plastic material additionally comprises the steps of:

[0182] o) heating the pyrolyzed liquid, solid or semi-solid residue (char) of step f) by heating a second heating jacketed fluid F2 and optionally by a gas heater, by electrical resistance (Joule effect), or a combination thereof.

[0183] Preferably, in step o), the char is heated to a temperature comprised between 500°C and 1200°C, preferably between 600°C and 1000°C, more preferably between 700°C and 900°C, for a period of time comprised between 5 minutes and 180 minutes, preferably between 30 and 120 minutes.

[0184] According to Figure 5 According to another embodiment of the application illustrated in Fig. 2, the condensation of the pyrolysis gas leaving the second pyrolysis reactor is divided in more than one unit (e.g. unit (72A) and unit (72B)). In more detail, the pyrolysis gas (54) leaving the second pyrolysis reactor (71) is passed at "high temperature" through a first condenser (72A) and a first separator (73A) which separates a condensed liquid (56A) from a non-condensed vapor (55A). The non-condensed vapor (55A) is then passed at "low temperature" through a second condenser (72B) and a second separator (73B) which separates a condensed liquid (56B) from a non-condensed vapor (55).

[0185] Advantageously, according to this embodiment, the cooling of the first condenser (72A) is performed by the high temperature thermal fluid (33E) which has already been used to heat the first pyrolysis reactor (70) before entering the cold reservoir (63). In this way, there is a heat recovery which allows to reduce the overall thermal load for condensing the pyrolysis oil and at the same time, by heating the high temperature thermal fluid, to reduce the required thermal load of the solar collector assembly (61).

[0186] According to one embodiment, the heating of the first pyrolysis reactor (70), of the char feeder device (75) and of the pre-heater (74) in the same temperature range can be performed using the heat carrier fluid (33) from the warm reservoir (64).

[0187] All other auxiliary and miscellaneous devices and parts connecting these devices (e.g. connecting pipes) can also be heated using the same heat carrier fluid.

[0188] Preferably, the distribution of the heat carrier fluid to these devices can be performed in series, in parallel or semi-series.

[0189] When in series, preferably the heat carrier fluid from the warm reservoir (64) is first fed to the pyrolysis reactor and then to other devices such as the pre-heater (74) or the char feeder device (75). More preferably, the order is: first pyrolysis reactor (70), then (if present) pre-heater (74) then (if present) char feeder device (75). According to other embodiments, if the condensation is divided in two or more steps and the cooling fluid in the first condenser is the heat carrier fluid, as Figure 5The description, this series also includes the first condenser, and preferably in the sequence, the last element is the first condenser. Thus, more preferably, the sequence is: first pyrolysis reactor (70), then (if present) pre-heater (74), then (if present) carbon feeder device (75), and finally (if present) first condenser (72A).

[0190] The semi-serial configuration is a combination of the serial and parallel configurations that allows to obtain the advantages of both the serial and parallel configurations.

[0191] Embodiments of the semi-serial configuration are described in Figure 6 and Figure 7 .

[0192] Figure 6 A weir device (78) is shown that receives the heat carrier fluid from the warm reservoir (64) and delivers this fluid to the first pyrolysis reactor (70) and to the pre-heater (74), and finally releases this fluid to the cold reservoir (63). According to this embodiment, the weir device comprises a first chamber in which the oil from the warm reservoir is sent. In this first chamber is positioned a first pump (66B) that delivers the heat carrier fluid to the first pyrolysis reactor (70). The heat carrier fluid that leaves the first pyrolysis reactor enters the same chamber. A weir, which can be for example a Bazin weir, ensures that there is enough pressure head (net positive suction head) to avoid cavitation of the heat carrier fluid pumped into the first pyrolysis reactor (70), as well as entrainment of gas phase. This weir also forms the containment wall of the first chamber, so that the fluid inside the chamber is recirculated. This ensures the uniformity of the temperature of the fluid inside the chamber, as well as a high resilience to instabilities in the flow rate of the fluid input from the warm reservoir.

[0193] The excess heat carrier fluid overflows from the weir, thereby entering a subsequent chamber. Similarly to the first chamber, in the subsequent chamber is positioned another pump (66B) that delivers the heat carrier fluid to the pre-heater (74) and collects its return. Similarly, another weir ensures that the pump (66B) that delivers the fluid to the pre-reactor has enough NPSH and is not entraining gas. Finally, the last chamber comprises another pump that delivers the heat carrier fluid to the cold reservoir (63). The start and stop of this pump can be handled automatically by a level switch, so that the pump is started only when the level of the last chamber is above a given height.

[0194] Unlike the serial configuration, the weir device (78) makes it possible to deliver heat carrier fluids at different flow rates to each device. Unlike the parallel configuration, in which all devices share the same source (warm reservoir), the weir device makes it possible to deliver heat carrier fluids at higher temperatures to devices that require higher temperatures and higher correlation (i.e. with a constant temperature of the heat carrier fluid if compared to the temperature of the successive chamber).

[0195] Thus, the weir device allows more flexibility and effectiveness if compared to a standard parallel configuration or a series configuration.

[0196] In another embodiment, this weir device can be located inside the warm reservoir itself, so that no pump is needed to deliver the heat transfer fluid to the weir device. In another embodiment, the warm reservoir, the cold reservoir and the hot reservoir can be located in a solar field, while the pyrolysis machine equipment can be located at a certain distance from the solar field. In this case, a buffer reservoir is needed to avoid any problem in the delivery of the heat transfer fluid that would determine the failure of the pyrolysis process.

[0197] In this case, the weir device can also be used as a buffer reservoir.

[0198] It should be appreciated that there are many different other customizations of the weir device, for example, allowing more chambers for managing more devices to be heated by the heat transfer fluid.

[0199] Advantageously, all the devices receiving the heat transfer fluid are placed at different height levels so that a minimum number of heat transfer pumps is needed.

[0200] More precisely, according to this embodiment, the first device receiving the heat transfer fluid from the pump 66 is located at the maximum height level, and the devices receiving the heat transfer fluid leaving the first device are located at lower height levels, so that the fluid can flow into the devices by gravity. By doing this, no additional pump is needed.

[0201] This is advantageous because any moving parts that are under fluid at a higher temperature, which can also exhibit a high melting temperature, are particularly vulnerable and can require special measures to be started correctly and, if they fail, to be maintained. In addition, in this way the pressure of the heat transfer fluid in the device can be atmospheric pressure, simplifying the design and reducing the cost of the device. Last but not least, when not under pressure, accidental rupture of the thermal jacket is much safer because the spillage resulting from the rupture is reduced.

[0202] According to a preferred embodiment, all the heat transfer fluid reservoirs are located at the bottom level.

[0203] The pre-heater (74) can be any device in which the plastic material can be heated and preferably partially or completely melted.

[0204] An example of such a device is a single-screw extruder, a twin-screw extruder, or more generally a screw device capable of delivering plastic material and having a jacket or equivalent member in which the heat transfer fluid can flow.

[0205] Optionally, the heat transfer fluid also flows inside the screw, thereby improving the efficiency of the device.

[0206] Preferably, the device is able to be almost airtight so that the gases in the first pyrolysis reactor (70) do not exit the pyrolysis reactor (70). The means to obtain this result is to use the same plastic melt flowing between the screw and the barrel as a method to obtain airtightness.

[0207] The pre-heating device can be equipped with a degassing device for evacuating water vapour and any other gases produced, in particular such as hydrogen chloride (HCI). To this end, in addition to the substantially plastic material, additives are advantageously also fed to the pre-heating device which are able to promote the evolution of hydrochloric acid or to salt it. These additives are preferably compounds of the IA and IIA groups of elements. Even more preferably they are oxides, hydroxides, carbonates, silicates and aluminosilicates of the IA and IIA groups. Even more preferably they are calcium oxide, calcium hydroxide, calcium carbonate, sodium oxide, sodium hydroxide, sodium carbonate, potassium oxide, potassium hydroxide, potassium carbonate, sodium aluminosilicate.

[0208] The pre-heating temperature can be between 120°C and 430°C, preferably between 150°C and 320°C, more preferably between 180°C and 220°C. The residence time in the pre-heating device is preferably less than 20 minutes, more preferably less than 4 minutes, in particular less than one minute.

[0209] An embodiment of the present application is therefore a process for producing at least one pyrolysis oil from a substantially plastic material, which process additionally comprises the following steps:

[0210] p) before step e), heating the substantially plastic material by heating the first heat transfer fluid (Fl).

[0211] According to this embodiment, it is preferred that in step p) the substantially plastic material reaches a temperature between 120°C and 430°C, more preferably between 150°C and 320°C, even more preferably between 180°C and 220°C, and wherein the average residence time of step p) is preferably less than 20 minutes, even more preferably less than 4 minutes, in particular less than one minute.

[0212] The first pyrolysis reactor (70) can be any reactor able to receive a substantially plastic feed and to bring it to pyrolysis conditions (temperature and pressure).

[0213] The first pyrolysis reactor for pyrolyzing the substantially plastic material can be operated in batch mode, continuous mode, and semi-continuous mode. In the latter mode, the substantially plastic material is continuously loaded, the produced vapours are continuously extracted, but any solid residue remains inside the pyrolysis reactor.

[0214] When the amount of solid residue inside the reactor rises above a certain threshold value, or at predetermined time intervals, for example with a frequency in the range of 2 to 10 days, the solid material contained in the reactor is removed.

[0215] Preferably, the reactor is operated in continuous or semi-continuous mode, more preferably in semi-continuous mode.

[0216] The pyrolysis process of the present application is not limited to a specific reactor type.

[0217] In particular, horizontal or vertical, stirred or non-stirred reactors, kiln reactors, or screw reactors can be used. Fluidized bed reactors are not preferred.

[0218] In stirred reactors, continuous stirred reactors (CSTR) and multi-zone reactors can be used. Plug flow reactors (PFR) can also be used, preferably stirred in order to facilitate heat transfer.

[0219] In continuous stirred reactors (CSTR), fully packed reactors (meaning that there is essentially no gas phase above the plastic melt being treated and the reaction products such as char) and reactors in which the gas phase is separated from the phases comprising liquids and other possible phases such as the solid carbon produced, i.e. reactors in which there is a free surface, can be used.

[0220] Preferably, the reactor is a stirred reactor with a free surface.

[0221] The residence time of the substantially plastic material (M1) in this first pyrolysis reactor is at least 2 minutes and is in any case sufficient to produce a fluid in gaseous state (M2) containing hydrocarbons. This means that in any case the residence time should be sufficient to produce a fluid in gaseous state and this time can be greater than 2 minutes. Depending on the composition of the substantially plastic material fed to the reactor, this time can vary, but it is not difficult for a person skilled in the art to increase the residence time so as to meet this condition if no gas is produced.

[0222] 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 membrane-faced thermocouple with the internal surface of the reactor aligned in order to reduce contamination; or a thermowell thermocouple for more precise measurement inside the reactor; or a thermocouple that measures the temperature of the metal near the surface of the reactor wetted by the polymer; or a non-contact measurement system, for example an infrared device. Several systems can be used simultaneously in order to improve reliability.

[0223] The temperature can be regulated by acting on the thermal power introduced into the reactor. The thermal power is obtained by the flow of the heat transfer fluid in the reactor.

[0224] The parts in contact with this heat transfer fluid are separated from the parts in contact with the process fluids (plastic inlet, liquefied plastic, char, gases produced by pyrolysis, etc.).

[0225] Preferably, the heat transfer fluid flows within a jacket. Alternatively, the heat transfer fluid also flows inside the agitator to heat the agitator.

[0226] Preferably, the heat transfer fluids F1 and / or F2 are molten salts. Any molten salt can be used in this invention.

[0227] The heat transfer fluid may be a low melting temperature alkali metal of group (III)A, (IV)A and (V)A (i.e., a metal alloy in which the elements belong to group (III)A to (V)A of the periodic table) and a metal alloy based on group (III)A, (IV)A and (V)A. Alkali metals include cesium (mp 28°C), lithium (180°C), potassium (63°C), neodymium (39°C), and sodium (mp 98°C); low-melting-temperature metals of 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); and metal alloys based on (III)A, (IV)A, and (V)A, where the total weight of elements belonging to groups (III)A to (V)A of the periodic table reaches at least 70% by weight, such as Wood's metal (50% bismuth, 26.7% lead, 13.3% tin, and 10% cadmium, mp 70°C) and Field's metal (32.5% Bi, 51% In, and 16.5% cadmium). Sn, mp 62℃), Rose's metal (50% bismuth, 25-28% lead and 22-25% tin, mp 98℃), Pewter metal (tin (85-99%), antimony (approx. 5-10%), copper (2%), bismuth, mp approx. 170-240℃), cast metal (40% Bi, 60% Sn, mp 170℃), lead-antimony eutectic (12% Sb, 88% Pb, mp 252℃), lead-tin eutectic (61.9% Sn, 38.1% Pb, mp 184℃), gallium-indium-tin alloy (68.5% Ga, 21.5% In, and 10.0% Sn, mp -19℃).

[0228] Among low melting temperature alkali metals, sodium and potassium are preferred; among group (III)A, (IV)A and (V)A metals, lead, bismuth, indium, gallium and tin are preferred; among metal alloys based on group (III)A, (IV)A and (V)A, Wood metal, Field metal, Ross metal, white tin metal, cast metal and gallium indium tin alloy are preferred.

[0229] According to one embodiment, the molten salt is a molten salt of Group IA and Group IIA of the periodic table, preferably sodium nitrate, sodium nitrite, potassium nitrite, potassium nitrate, lithium nitrate, calcium nitrate, or a mixture thereof.

[0230] According to one embodiment, the molten salt that can be used is a nitrate / nitrite mixture, and optionally a mixture of sodium nitrite and calcium nitrate, consisting of potassium nitrate and sodium nitrate, is also added.

[0231] According to one embodiment, the nitrate / nitrite mixture is a eutectic mixture of 53 wt% potassium nitrate, 40 wt% sodium nitrite and 7 wt% sodium nitrate; alternatively, according to another embodiment, the K / Na nitrate / nitrite mixture is a eutectic mixture of 45.5 wt% potassium nitrate and 54.5 wt% sodium nitrite.

[0232] According to one embodiment, this nitrate / nitrite mixture is a so-called "sun salt" characterized by 60 wt% sodium nitrate and 40 wt% potassium nitrate.

[0233] According to one embodiment, this nitrate / nitrite mixture is a so-called "Hitec XL" characterized by 7 wt% sodium nitrate, 45 wt% potassium nitrate and 48 wt% calcium nitrate.

[0234] According to one embodiment, the nitrate / nitrite mixture is 100 wt% lithium nitrate.

[0235] According to one embodiment, the nitrate / nitrite mixture comprises 25 wt% lithium nitrate, 25 wt% sodium nitrate, and 50 wt% potassium nitrate.

[0236] According to one embodiment, the molten salt is a mixture of chlorides (such as sodium chloride) and a mixture of sodium chloride and potassium chloride, optionally with magnesium chloride.

[0237] According to other embodiments, the heat transfer fluid is a molten salt comprising Group IA and Group IIA metal fluorides, preferably lithium fluoride, sodium fluoride, potassium fluoride, and calcium fluoride. Even more preferably, the heat transfer fluid is composed of a molten salt comprising sodium nitrite, sodium nitrate, and potassium nitrate. Even more preferably, the heat transfer fluid is composed of a molten salt comprising sodium nitrate and potassium nitrate.

[0238] Preferably, the heat transfer fluid has a low melting temperature. More preferably, the melting temperature is at most 340°C, even more preferably at most 270°C, and even more preferably at most 240°C.

[0239] Preferably, the heat transfer fluid has a high decomposition temperature. More preferably, the decomposition temperature is at least 400°C, even more preferably at least 450°C, and even more preferably at least 490°C, and most preferably at least 540°C.

[0240] According to one embodiment, the melting temperature of the heat transfer fluid is at least 60°C, preferably greater than 80°C, and more preferably greater than 105°C.

[0241] Preferably, the heat transfer fluid has a low chloride content. More preferably, the chloride content is less than 1000 ppm by weight. More preferably, the chloride content is less than 100 ppm by weight.

[0242] According to one embodiment, any component of a process intended to contain molten salt, such as, for example, a reactor, coker, preheater, valve, etc., can be discharged by gravity. For example, the storage tank (hot, cold, warm) can be located at the lowest point so that in the event of a failure (such as a failure of the molten salt pump 66, or a sudden interruption of electrical power), the heat transfer fluid is discharged to the storage tank by gravity. According to another embodiment, any component containing molten salt, characterized by the presence of moving parts (such as valves) or a large aspect ratio (e.g., pipes), has an electrically heated line that can be activated before starting the equipment to melt the heat transfer medium.

[0243] The solar collector assembly (SCA) can be of any type. According to one embodiment, the solar collector is a "single-focus" collector, meaning that solar rays are reflected to a focal area that is substantially limited in size. Examples of a "single-focus" collector are parabolic troughs and power towers. According to another embodiment, the solar collector is a "focal line" collector, meaning that solar rays are reflected to a focal area that is substantially a line. Examples of this type of solar collector are parabolic troughs and linear Fresnel reflectors. Several specific types of parabolic troughs and linear Fresnel reflectors also exist that can be used in this invention, such as "compact linear Fresnel reflectors" (CLFRs) or "enclosed trough systems."

[0244] Preferably, the solar collector is a parabolic trough or a linear Fresnel, in the latter case, a particularly compact linear Fresnel.

[0245] Therefore, according to one embodiment of the method of the invention, the heating in steps a) and b) is performed by at least one solar collector assembly comprising a parabolic trough, a linear Fresnel collector, or a combination thereof. According to a preferred embodiment of the method of the invention, the heating in steps a) and b) is performed by at least one solar collector assembly comprising a parabolic trough, a linear Fresnel collector, or a combination thereof.

[0246] The solar rays collected by this collector are reflected to a so-called solar receiver. In one embodiment, this solar receiver consists of a heat exchanger in which a heat-carrying fluid is heated. Typically, in this receiver, the fluid flows in a tube heated by solar rays.

[0247] In another embodiment, this solar receiver consists of a tube in which solar rays are directed. The tube, typically a metal tube, is called the "absorber." The tube is coated with a selective coating that maximizes solar absorption while minimizing heat loss through infrared emission. The glass tube surrounding the absorber tube is transparent to allow sunlight to pass through. A high vacuum is created between the two tubes to limit convective heat loss. Sometimes a degassing nozzle and / or getter are added to maintain this vacuum over time.

[0248] The solar receiver has a corrugated tube at the end to account for the difference in thermal expansion between glass and metal materials.

[0249] Solar collectors and associated receivers can be assembled in parallel, in series, or a combination of parallel and series configurations. A combination of parallel and series configurations is preferred.

[0250] In some cases, such as linear Fresnel (and compact linear Fresnel), a single receiver can receive concentrated solar radiation from multiple reflectors.

[0251] The focusing factor (sometimes referred to as the focusing ratio) is the ratio of the radiant power density at the receiver to the radiant power density of sunlight without any focusing, and thus it is the coefficient by which the incident energy flux on the receiving surface is optically enhanced. According to the invention, the focusing factor is 8 to 1000, preferably 10 to 100, and even more preferably 15 to 80.

[0252] According to one embodiment of the present invention, the solar collector assembly 62 of the heated thermal storage tank 65 has a higher concentration coefficient than the solar collector assembly 61 of the heated warm storage tank 64.

[0253] Therefore, according to one embodiment of the method of the present invention, the concentration coefficient of at least one solar collector assembly in step b) is higher than that of at least one solar collector assembly in step a).

[0254] Hot storage tanks, warm storage tanks, and cold storage tanks can be any container that can be filled with a heat-carrying fluid, such as vertical or horizontal tanks. Advantageously, this container is thermally insulated to limit heat loss.

[0255] According to one implementation, the heat transfer fluid pump 66 is located inside the storage tank.

[0256] According to one implementation, the level of the heat transfer fluid in the storage tank is monitored so as to limit the pyrolysis load when the level of the heat transfer fluid in the hot or warm storage tank becomes too low.

[0257] According to one embodiment of the invention, there are also other storage tanks for the heat transfer fluid, so as to deliver the heat transfer fluid at more than two temperatures to the pyrolysis apparatus.

[0258] According to one embodiment, this first pyrolysis reactor is preferably a vertical vessel having a substantially cylindrical shape.

[0259] Preferably, the top and bottom ends of the first pyrolysis reactor are conical, elliptical, or semi-elliptical. This allows for better recycling and results in less contamination, which is, in fact, critical in pyrolysis reactors.

[0260] Preferably, the first pyrolysis reactor 70 has at least one agitator. This agitator should be of appropriate size to ensure that the entire volume of the reactor, filled with at least both liquid and solid phases, is continuously or semi-continuously wiped (e.g., not necessarily gaseous phase). Preferably, the agitator should be able to periodically move material near the reactor walls to clean surfaces and reduce contamination.

[0261] Examples of this agitator are anchor agitators or strip agitators, or in some cases, turbine agitators.

[0262] The speed of this mixer is typically 1 to 300 rpm, preferably 5 to 120 rpm.

[0263] According to some implementation schemes, more than one agitator may be used. In this case, it is advantageous for the agitators to have different agitator speeds. A simple way to accomplish this is to keep one agitator freely rotating so that it is entrained by the fluid to a rotational speed that is lower than, but greater than, zero, than one of the actively operating agitators.

[0264] A condenser is any device that receives a gaseous fluid and is able to remove sufficient heat from the fluid to produce at least a portion of the fluid in a liquid state.

[0265] An example of this device is a condenser containing coils inside which a heat-carrying fluid flows, capable of removing heat from the gaseous fluid being processed.

[0266] Other methods of heat removal may also be used, for example, alternatively or in combination, the condenser may have a jacket in which the heat transfer fluid flows in order to remove heat.

[0267] An immersion condenser can also be advantageously used, in which the condenser is partially submerged by the resulting liquid phase, and its condensing power is adjusted by changing the height of this liquid phase, since only the unsubmerged coils can absorb calories from the vapor to be condensed. Therefore, this allows for efficient regulation of the condenser's power.

[0268] Alternatively, the condenser can consist of a distillation column. In this case, the condensate originates from the condenser of the column, and the condensate flows back to the column by gravity or by pumping, causing the vapor inside to condense. In this way, better fractionation of the input vapor is also achieved, i.e., better separation between the higher boiling components that condense and the lower boiling components that remain in the vapor phase, because there is concentration of the heavier material in the liquid phase and concentration of the lighter material in the gas phase at each stage. Furthermore, the washing of the vapor operated through the column allows any solid particles present in the input vapor to separate and re-aggregate in the liquid phase.

[0269] The condenser for the pyrolysis vapor can be a single condenser or a series of condensers in parallel. Preferably, when using more than one condenser, two to four condensers are used in series, and even more preferably three condensers are used in series.

[0270] When condensers are connected in series, each condenser receives uncondensed gas leaving the previous condenser, while the first condenser receives pyrolysis vapor.

[0271] In this preferred mode, the condenser receiving pyrolysis vapor (the first condenser) operates at a higher temperature than the second condenser, which receives uncondensed vapor from the first condenser. If more condensers are available, the next condenser (e.g., the third condenser) receives uncondensed vapor from the previous condensers and operates at a lower temperature.

[0272] According to a preferred method, a portion of the fluid in the liquid state condensed in at least one condenser is recycled to the first pyrolysis reactor. Preferably, the fluid recycled to the reactor is obtained from the first condenser.

[0273] According to one implementation scheme, when using more than one condenser, if it has already been installed... Figure 5 As described, heat is removed by a first condenser (condenser 72A) via a heat transfer fluid.

[0274] The hydrocarbon-containing fluid, defined below as residual gas, that has not condensed after passing through the at least one condenser advantageously contains at least 40% by weight of light hydrocarbons (C1-C5) and can be advantageously used as a fuel gas. A portion of this gas can be combusted to supply additional heat energy suitable for pyrolysis processes and related equipment, particularly equipment requiring higher temperatures (such as second pyrolysis reactors and coking plants). 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 or in combination, this residual gas can be advantageously used to supply refining equipment, such as, for example, cracking equipment.

[0275] According to the invention, the amount of fluid in a liquid state after condensation in the at least one condenser is at least 10% by mass relative to the mass of the substantially plastic material being fed in, preferably between 20% and 92%, more preferably between 30% and 85%, and even more preferably between 40% and 75%. If multiple condensers are used, this amount is calculated by adding the mass of liquid produced by each condenser.

[0276] According to the invention, after condensation in the at least one condenser, at least one fluid is formed, which is in a liquid state and contains hydrocarbons having a standard boiling point of not less than 25°C, preferably not less than 40°C, more preferably between 80°C and 220°C.

[0277] Preferably, at least the first pyrolysis reactor operates at atmospheric pressure or above atmospheric pressure (i.e., greater than atmospheric pressure). According to one embodiment, the pressure is between 1.1 and 20 bar, more preferably between 2 and 10 bar, and even more preferably between 2.2 and 6 bar.

[0278] Preferably, the temperature reached by the essentially plastic material in the first pyrolysis reactor is 330°C to 580°C, more preferably 340°C to 540°C, even more preferably 360°C to 500°C, even more preferably 380°C to 480°C, and even most preferably 410°C to 450°C.

[0279] Any technique known in this art can be used to maintain the pressure in the first pyrolysis reactor at a predetermined value, wherein the maintained pressure may have different values ​​that vary with the pyrolysis temperature. According to the first method, the pressure can be maintained at the predetermined value by adjusting the heat extracted from a condenser located downstream of and in fluid communication with the reactor. In this mode, the increase in heat removed from the condenser leads to greater vapor condensation. This condensation, which causes the evaporating material to move from a gaseous state to a liquid state with a greater density, results in a decrease in pressure.

[0280] Alternatively, the pressure can be controlled by introducing a gas (such as nitrogen, argon, or water vapor) and regulating the flow of this gas via a valve. According to one embodiment, this gas is introduced into the first pyrolysis reactor and acts as an inert gas (i.e., a gas that does not directly participate in the pyrolysis reaction and, for example, removes oxygen present in the reactor when the reactor is connected to the atmosphere, for example during maintenance or before reactor startup).

[0281] According to the preferred embodiment, the pressure can be controlled by adjusting the flow of the uncondensed airflow (or the airflow of the last condenser if more than one condenser is used in series).

[0282] According to one embodiment, the pyrolysis of the plastic material of the present invention is carried out in the absence of oxygen, wherein the meaning of "the absence of oxygen" is as defined above.

[0283] Therefore, according to this embodiment, the method for producing at least one pyrolysis oil from essentially plastic materials is further characterized by the fact that steps f) and h) are performed in the absence of oxygen.

[0284] The thermal power of the first and second pyrolysis reactors can be controlled by adjusting the flow rate of the heat transfer fluid, its temperature, or both.

[0285] Advantageously, the pyrolysis process of the present invention produces products particularly suitable for use as jet fuel or as a product of crude naphtha, which is particularly suitable for steam cracking to produce industrially significant monomers or for synthesizing polymers.

[0286] Preferably, 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.

[0287] According to another embodiment, the second pyrolysis reactor is always operated at a temperature at least 10°C higher than that of the first pyrolysis reactor, with the additional condition that this temperature is between 400°C and 650°C, preferably between 440°C and 550°C, and more preferably between 460°C and 530°C; this means that when the lowest temperature in this range is lower than the temperature of the first pyrolysis reactor plus 10°C, the latter (Tfirst pyrolysis reactor+10°C) should be considered the lower range.

[0288] Therefore, a method for producing at least one pyrolysis oil from a substantially plastic material is included in the present invention, wherein the gaseous effluent from a first pyrolysis reactor, before condensation, reaches a second pyrolysis reactor, wherein the gas stream is heated to a temperature at least 10°C higher than the temperature of the substantially plastic material in the first pyrolysis reactor.

[0289] Therefore, according to one embodiment of the invention, a method is provided for producing at least one pyrolysis oil from essentially plastic materials, wherein the temperature difference between the temperature T2 of step b) and the temperature T1 of step a) is at least 10°C, more preferably between 30°C and 300°C, and even more preferably between 60°C and 250°C.

[0290] The residence time of the pyrolysis vapor in the second pyrolysis reactor, calculated by dividing the volume occupied by the vapor in the reactor and the volumetric flow rate, is at least 10 seconds, preferably between 30 seconds and 6 minutes, and even more preferably between 1 minute and 4 minutes.

[0291] 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 it, and the relative motion is at a speed of at least 0.5 m / s, more preferably 2 m / s to 50 m / s.

[0292] All known pyrolysis catalysts in the prior art can be used, especially zeolites.

[0293] The second pyrolysis reactor may operate at the same pressure as or at a lower pressure than the first pyrolysis reactor 70; preferably, the second pyrolysis reactor operates at a pressure between atmospheric pressure and the pressure of the first pyrolysis reactor. Even more preferably, it operates at a pressure between the pressure of the first pyrolysis reactor and that pressure reduced by 10,000 Pa.

[0294] Advantageously, the first pyrolysis reactor can be more than one unit, and the same applies to the second pyrolysis reactor. In this way, the process can be easily scaled up.

[0295] Additionally, when liquid / solid / semi-solid residue (carbon) accumulates in a unit of the first reactor, that unit can be stopped, the carbon discharged, the unit cleaned, and then restarted. If the production schedule for each first pyrolysis reactor is programmed, the shutdown of individual units can be scheduled for periodic and sequential maintenance, thereby maintaining the stability of the entire pyrolysis process over time.

[0296] Advantageously, the second pyrolysis reactor can be fed with pyrolysis steam from the outlet of one or more first pyrolysis reactor units. Preferably, gaseous steam from two to twenty first pyrolysis reactor units, or even more preferably three to eight units, is fed into a single second pyrolysis reactor.

[0297] Similarly, char produced by more than one first pyrolysis reactor unit is fed into a single char processing unit (such as a "coking unit").

[0298] To sustain the pyrolysis process and provide the necessary heat when solar radiation is too low (e.g., after sunset or under cloudy or rainy conditions), heat transfer fluids accumulated in hot and warm storage tanks can be used. Typically, the tank temperatures remain unchanged to ensure stable pyrolysis and to maintain the quality of the obtained pyrolysis oil.

[0299] Conversely, the flow rate of the heat transfer fluid in the load section (solar collector assembly) can be stopped or reduced, while maintaining (or slowly reducing) the flow rate of the heat transfer fluid from the thermal and warm storage tanks. In this way, the level of the heat transfer fluid in the thermal storage tank decreases, and the level in the warm storage tank may also decrease (depending on the relevant mass flow rate ratio), while the level in the cold storage tank increases.

[0300] The larger the volume of the storage tank, the longer the period during which the method can be operated with an additional power source. Especially in this case, the size of the storage tank can be very large, thus allowing it to be conveniently divided into more units, which can, for example, operate in parallel.

[0301] Energy accumulation and the time required for complete discharge can also be increased by exchanging heat energy between the heat transfer fluid and a solid material (such as concrete, sand, stone, etc.) that can maintain the temperature of the heat transfer fluid. A simple means of carrying out this embodiment is to place a large amount of material on the tank or its walls, or as its base.

[0302] Additional power sources are energy sources other than concentrated solar power (CSP), which can be used for, for example, emergency shutdowns or starting equipment. Alternatively or in combination, these additional power sources can be used, for example, to stabilize or enhance pyrolysis production. These sources can be, for example, so-called renewable sources (such as wind, solar photovoltaic, tidal, nuclear, hydropower, biomass) or fossil fuels (carbon, oil, shale, natural gas).

[0303] Preferred sources of these additional power sources are photovoltaic, biomass, nuclear, and natural gas, with natural gas being particularly preferred.

[0304] In the case of natural gas, a gas heater is particularly preferred. Even more preferably, the gas burned in the gas heater contains residual gas from the pyrolysis process (i.e., uncondensed pyrolysis gas, as already described, for example...). Figure 11 (55 in the middle).

[0305] This additional power source can be connected in series or parallel with the heat transfer fluid to be heated.

[0306] Figure 11 This invention illustrates some embodiments of the invention, including such additional power sources in parallel (68A) or in series (68B) and (68C).

[0307] Parallel configuration means that, parallel to the solar collector assembly, the power source draws a portion of the heat transfer fluid from a cooler tank (cold or warm), heats the fluid to a target temperature (typically the temperature of the destination tank), and delivers the heat transfer fluid to that destination tank. If the fluid is drawn from the cold tank (63), the destination tank is either the warm tank (64) or the hot tank (65), and if the fluid is drawn from the warm tank (64), the destination tank is the hot tank (65).

[0308] When configured in series, the inlet of this additional power source is the outlet of the solar collector assembly, and its outlet is the inlet of the heat transfer fluid storage tank. (Reference) Figure 11An embodiment of this solution is as follows: heat transfer fluid from the heat storage tank (64) is sent to the thermal solar collector assembly (62), then to an additional power source (68B), and then to the heat storage tank (65).

[0309] Alternatively, in a series configuration, the inlet of this additional power source is the outlet of the thermal storage tank, and the outlet is the discharge loop of the thermal storage tank (the loop supplying the second pyrolysis reactor and, optionally, the coking unit). This is the preferred option.

[0310] refer to Figure 11 An embodiment of this solution is as follows: heat transfer fluid from the heat storage tank (65) is sent to an additional power source (68C) and then to the load (second pyrolysis reactor 71).

[0311] Preferably, when this additional power source is present, its power is between 3% and 40% of the power supplied by the thermal solar collector assembly and the warm solar collector assembly, more preferably between 6% and 20%, and even more preferably between 8% and 15%.

[0312] Example

[0313] This embodiment reports a simulation of the method using the dual-heat-carrying fluid drive method (dual-loop) of the present invention, compared to a conventional single-fluid-driven method (single loop). For clarity, it is a predictive embodiment and therefore uses the present tense.

[0314] Example 1 (Invention)

[0315] The solar pyrolysis method drives two fluids (dual heat-carrying fluid loops) with the same composition.

[0316] The method corresponding to this embodiment is Figure 8 The information is provided in the text.

[0317] The heat transfer fluid is a solar mixture of molten salt containing 60 wt% sodium nitrate and 40 wt.% potassium nitrate (“solar salt”).

[0318] The solar collectors and receivers (61) and (62) consist of a Luz (SEGS) LS-2 type parabolic trough collector (PTC) with a 70 mm outer diameter vent pipe solar receiver. This model has a width W of 5.0 m and a length L of 7.8 m. Detailed characteristics and characterization of this parabolic trough collector are reported in Dudley V, Kolb G, Sloan M, Kearney D., “SEGS LS2 solar collector-test results”. 958 Report of Sandia National Laboratories, SAN94-1884, 1994, and briefly reported in Tables 1 and 2 of Bellos, Evangelos & Tzivanidis, Christos, “A detailed exergetic analysis of parabolic troughcollectors”, Energy Conversion and Management, (149) 275-292, 2017 doi:10.1016 / j.enconman.2017.07.035. The paper referred to below as Bellos's paper also addresses the detailed energy and available energy balance.

[0319] The code for the model developed in Bellow's paper was prepared and tested to validate Sandia National Laboratories Test Case 4 (Table 4 on page 11 of Bellow's paper). The results corresponded well to the results in Tables 4 and 5 of Bellow's paper shown in this test case, and thus showed a very close approximation to the experimental values.

[0320] The molten salt flow rate in the solar collector assembly (62) is 24.2 kg / s. The receivers of the solar collector assembly are arranged in 20 parallel lines, each receiving 24.2 / 20 = approximately 1.21 kg / s of solar salt. Each line contains 19 receivers. This is the number of receivers (each 7.8 m long) required to increase the temperature from 485°C to 565°C. The calculations were performed as follows: the environmental conditions (ambient temperature, sky temperature, sunlight temperature, angle of incidence) were based on Table 3 of Bellow's paper, except that the specific air humidity (humidity ratio) was understood to be 0.01 (i.e., 10 g water / kg air). In addition, the direct beam solar irradiance (Gb) was selected as 650 W / m. 2 Because of the approximately 900 W / m reported in Table 4 of Bellow's paper. 2 The values ​​are quite high and are available only in selected areas of Earth and for limited time periods. PTC module characteristics and optical properties are based on Tables 1 and 2 of Bellow's paper. The equations used are described in Bellow's paper.

[0321] The physical properties of the "solar salt" heat transfer fluid were calculated using the following expressions obtained from A. Bonk et al., "Solar Salt-thermal Property Analysis", Scientific Report DLR-FB-2021-19 31.08.2021, Deutsches Zentrum für Luft- und Raumfahrt:

[0322]

[0323] Heat capacity is considered to be independent of temperature because there is significant inconsistency in the measurement results of this parameter, so a constant value is used.

[0324] To perform the calculations, Bellow used the software "Engineering Equation Solver," but found that its available algorithms could be easily solved in any programming or scripting language because the most difficult equation to be solved was a quartic equation (a quartic polynomial) to calculate the covering temperature ("Tc," in Kelvin). This equation had only two real roots, only one of which was positive (therefore only this root was meaningful and had to be chosen). With two iterative calculations (outlet temperature and Tc), the solution converged very quickly anyway, and there was no alternative solution.

[0325] Starting with the first receiver that receives molten salt from the cold storage tank, simulations are performed for each solar receiver. The calculated temperature of the molten salt at the outlet of the first receiver is set as the inlet temperature of the molten salt at the inlet of the second receiver. Therefore, the temperature of the molten salt at the outlet of the second receiver can be calculated, which becomes the inlet temperature of the molten salt at the third receiver, and so on. In this way, the number of receivers required to reach the target molten salt temperature can be calculated (in this case, 19 receivers per line to reach 565°C).

[0326] Total energy and available energy flow are calculated by adding the contributions of each receiver.

[0327] The solar assembly (62) receives solar salt from the warm storage tank (64), heats the solar salt to the target temperature, and then sends the hot solar salt to the warm storage tank (65). From the warm storage tank, the solar salt is sent to the units requiring the maximum operating temperature: the coker (76) and the secondary pyrolysis reactor (71).

[0328] The molten salt is fed directly to the coking unit, without a weir. A weir would allow for precise temperature control and higher flow rates (which are not necessary in a coking unit), but at the cost of reduced flow rates, while the coking unit benefits from the higher temperature of the molten salt in the jacket.

[0329] The molten salt fed into the first pyrolysis reactor (70) and the second pyrolysis reactor (71) is delivered via weir devices (78), (79). These weir devices have two chambers. The first chamber receives the hot molten salt and delivers it to the jacket of the pyrolysis reactor (e.g., via a submersible pump). Unlike Figure 6 and Figure 7 The described weir device directs the molten salt returning from the reactor to the second chamber. The flow rate of the molten salt circulating in the pyrolysis reactor is much higher than the flow rate of the hot molten salt delivered from the storage tank. This higher flow rate is desirable because it reduces temperature differences within the pyrolysis reactor and maximizes heat transfer. Therefore, a portion of the molten salt in the second chamber overflows the weir between the first and second chambers and falls into the first chamber. This ensures that the pumps in the first chamber can deliver the required flow rate while maximizing the temperature of the molten salt delivered to the pyrolysis reactor.

[0330] Molten salt from the coker is delivered to a weir device (79), which feeds the molten salt into a second pyrolysis reactor (71). Molten salt leaving the weir device (79) is sent to a warm storage tank (64), thereby closing the “thermal loop” of the heat transfer fluid.

[0331] The solar receiver (61) receives solar salt from the cold storage tank (63), heats the solar salt to a target temperature (in this case, 485°C), and then sends the warm solar salt to the warm storage tank (64). The solar receiver (61) is made of 75 parallel lines, each containing 8 receiver tubes connected in series (each receiver tube is always 7.8 m long). In this way, the flow rate of each line is 91.6 / 75 = 1.22 kg / s, which is very similar to the flow rate of the heat receiver (62).

[0332] Ensure that the flow rate in the receiver tube is sufficiently high as required for the safe operation of the solar collector assembly, especially to reduce the temperature difference between the sections of the tube exposed to different intensities of sunlight and the associated bends of the tube.

[0333] From the warm storage tank, solar salt is sent to the first pyrolysis reactor (70) via a weir device (78).

[0334] A portion of the solar salt leaving the first pyrolysis reactor is sent to a heat exchanger (81). The heat exchanger is a heat exchanger that heats an organic heat transfer fluid (Marlowem SH, via Eastman) called "oil" to approximately 320°C through the molten salt from the first pyrolysis reactor at a "low" temperature.

[0335] Using an organic heat transfer fluid is advantageous for use at low temperatures because it has a low melting temperature, thereby eliminating the risk of solid salt freezing in areas where circulation is lacking or thermal insulation is insufficient. Furthermore, electrical wiring is not necessary for oil-jacketed lines. When the required load is much less than the load of the first pyrolysis reactor, only a portion of the molten salt leaving the first pyrolysis reactor deviates to the hot oil exchanger.

[0336] The solar salt leaving the first pyrolysis reactor is collected in a cold molten salt storage tank (63), thereby closing the "warm loop" of the molten salt.

[0337] The heat loss in the solar receiver (62) is calculated in the aforementioned Bellow model. Such heat loss is ignored when the heat loss in the so-called manifolds and connecting pipes of the solar collector assembly is considered negligible compared to the heat loss in the receiver.

[0338] The heat loss in the molten salt circuit, which includes the coker, the second pyrolysis reactor, and related connecting pipes, is concentrated in the concentrating heat loss (83), referred to as "enthalpy loss 2". The heat loss in the molten salt circuit, which includes the first pyrolysis reactor, the hot oil exchanger, and related connecting pipes, is concentrated in the second concentrating heat loss (82), referred to as "enthalpy loss 1".

[0339] In addition to the solar collector assembly (SCA) that performs calculations following the aforementioned model and Bellow equations, the inner wall of the molten salt circulation within it is considered as a control volume to perform available energy balance. Therefore, for the SCA alone (e.g., for available energy input), the boundary lies on the input radiation from sunlight.

[0340] Since there is no material flow crossing the selected boundary, the only available energy flow is:

[0341] - Enter the available solar irradiance (marked with "+").

[0342] - Output available energy related to heat flow at the following locations:

[0343] ○ Pyrolysis reactor, coking unit, hot oil exchanger

[0344] ○ Heat loss concentrated in the “enthalpy loss” device.

[0345] It can be assumed that the temperature at the boundary changes linearly with heat flow. This assumption is even more realistic, considering that the temperature change along the heat flow boundary is relatively small compared to its absolute value (in Kelvin). Therefore, the available energy flow at such boundaries can be calculated using the following equation:

[0346]

[0347] in:

[0348] -T1 and T2 are the temperatures in Kelvin at the beginning and end of the heat exchange boundary.

[0349] -T0 is the reference temperature (298K in this article).

[0350] -ΔQ is the heat flow.

[0351] -Δx represents the available energy flow rate.

[0352] T1 and T2 correspond to the inlet and outlet temperatures, except when a weir is used. In fact, in this case, the recirculation pump inside the weir reduces the temperature difference between the inlet and outlet of the recirculated molten salt flow (in the case of unlimited flow rate, T1 equals T2).

[0353] The table below reports the detailed calculations, as well as the calculations of total heat and available energy flow obtained by summing all individual contributions.

[0354]

[0355]

[0356] It can be observed that when the sum of all available energy contributions is positive, the enthalpy balance (“heat flow”) is zero (meaning that all net energy received from the solar collector assembly is delivered to the load or lost in the concentrated “enthalpy loss”).

[0357] This available energy imbalance takes into account the available energy loss for SCA only (related to heat loss), plus available energy destruction (related to irreversible thermal quality loss, i.e., when mixing two fluids at different temperatures: the enthalpy is the same before and after mixing, but the available energy is lost in the opposite way).

[0358] This embodiment is applicable to the pyrolysis of the following mixed plastic waste:

[0359] Basically, plastic material (mixed plastic waste) is fed into the screw heater, whose jacket is heated by an organic heat transfer fluid (Marlowem SH), which is heated by a heat exchanger to a temperature of about 290°C.

[0360] Heating from the extruder essentially involves feeding the plastic material into the first pyrolysis reactor, where it is heated by molten salt at a "warm" temperature, during which it pyrolyzes to form a gaseous phase and a semi-solid phase (carbon). The reactor is a basically vertical cylinder with an anchor agitator.

[0361] - The gaseous effluent from the first pyrolysis reactor is fed into the second pyrolysis reactor. This reactor is a basically tubular heat exchanger, which may optionally be filled with a catalyst, wherein the pyrolysis vapors are heated and further pyrolyzed into smaller molecules.

[0362] - The gaseous effluent from the second pyrolysis reactor is fed to the condensation section, wherein at least one liquid stream is obtained, which is more than 10 wt% of the initial weight of the fed plastic material and contains a large fraction of hydrocarbons.

[0363] The char obtained in the first pyrolysis reactor is sent to a coker heated by hot molten salt to produce a solid material with a better HSE profile (health, safety, environment) and suitable not only as an energy source but also as a packing agent. The gas developed in this process is then directed to the condensation section, thereby increasing the pyrolysis yield.

[0364] Comparative Example 2

[0365] A solar pyrolysis method driven by a single fluid (single heat transfer fluid loop).

[0366] The method corresponding to this embodiment is Figure 9 The information is provided in the text.

[0367] The heat transfer fluid is the same solar mixture (“solar salt”) of the molten salt of Example 1, and uses the same physical property relationships.

[0368] The solar collector assembly (62) is of the same type as in Example 1.

[0369] The code used to calculate the performance of the solar receiver is the same code used in Example 1, and has the same values ​​for geometric, optical, physical constants and environmental conditions.

[0370] The molten salt load was the same as in Example 1 in terms of heat flow power (in watts) and the inlet and outlet temperatures of the molten salt.

[0371] Under these constraints, the required mass flow rate of the molten salt passing through the solar receiver (63) is 42.6 kg / s. The inlet temperature of the solar salt is 418°C and the outlet temperature is 565°C.

[0372] The heat receiver (64) receives the solar salt leaving the SCA (62). The hot solar salt from the heat storage tank is sent in parallel to the units requiring maximum operating temperatures (e.g., coker 76 and secondary pyrolysis reactor 71) and the first pyrolysis reactor (70). In fact, the first pyrolysis reactor requires a larger heat flow at a lower temperature. Therefore, Figure 9 The setup shown and detailed herein is specifically designed to maximize the effectiveness of this configuration: after passing through the coker and the second pyrolysis reactor, the solar salt is at a sufficiently high temperature to heat the first pyrolysis reactor, but its quantity is insufficient for the required (larger) heat to be supplied. Therefore, an additional flow of solar salt is fed directly from the thermal storage tank to the first reactor.

[0373] Heating of the first pyrolysis reactor (70) and the second pyrolysis reactor (71) is performed by weir devices (78), (79). These weir devices are the same devices used in Example 1.

[0374] A portion of the solar salt leaving the first pyrolysis reactor is sent to a heat exchanger (81). The heat exchanger is a heat exchanger that heats the organic heat transfer fluid with molten salt from the first pyrolysis reactor at a “low” temperature, in the same manner as in Example 1.

[0375] When the required load is much less than the load of the first pyrolysis reactor, only a portion of the molten salt leaving the first pyrolysis reactor deviates to the hot oil exchanger.

[0376] The solar salt leaving the first pyrolysis reactor is collected in a cold molten salt storage tank (63), thereby closing the (single) molten salt loop.

[0377] As in Example 1, the heat loss in the molten salt circuit, including the coker, the second pyrolysis reactor, and the associated connecting pipes, is concentrated in the concentrating heat loss (83), referred to as "enthalpy loss 2". The heat loss in the molten salt, including the first pyrolysis reactor, the hot oil exchanger, and the associated connecting pipes, is concentrated in the second concentrating heat loss (82), referred to as "enthalpy loss 1".

[0378] Available energy balancing is performed in the same way.

[0379] The table below reports the detailed calculations, as well as the calculations of total heat and available energy flow obtained by summing all individual contributions.

[0380]

[0381] It can be observed that when the sum of all available energy contributions is positive, the enthalpy balance (“heat flow”) is zero (as in Example 1).

[0382] Comparison of Example 1 and Comparative Example 2

[0383] The table below shows the load of Example 1 compared to Comparative Example 2:

[0384]

[0385] In both cases, all loads are the same in terms of heat flow and available energy flow. Although the inlet temperatures in the weir differ, the latter are the same because the internal circulation pump ensures the same temperature difference (T1 and T2 are the same in Example 1 and Comparative Example 2).

[0386] Therefore, it can be shown that both Example 1 and Comparative Example 2 deliver the same load to the load at the same temperature, and thus the pyrolysis method shows no difference. However, the available energy balance is different: in fact, Example 1 has an imbalance of 14918 kW, while Comparative Example 2 has an imbalance of 16570 kW, which is about 11% more.

[0387] This means that Comparative Example 2 is less effective because it requires the same amount of energy but at a higher quality level (more energy at a higher temperature).

[0388] The reason is that whenever two streams at different temperatures are mixed, energy is conserved but available energy is not. In fact, in this operation, the stream at the higher temperature (and therefore at a higher quality) is irreversibly disrupted.

[0389] Ultimately, the superior efficiency of the method in Example 1 results in lower requirements for land and equipment installation and operation costs, as shown in the table below:

[0390]

[0391] By dividing the solar salt filler (solar collector assembly, SCA) into two separate units, a flow of "thermal energy"—a higher temperature but not a high quantity of molten salt—and a flow of "warm energy"—a lower temperature but a higher quantity of molten salt—are generated. The solar collector is more effective for heating cryogenic hot fluids because heat loss is much lower, especially since the vent pipe allows for a significant reduction in thermal conductivity, but it does not limit radiative emission, which increases with temperature and power, even without considering the considerable increase in emissivity of the cermet material applied to the receiver tube (to limit emissivity) exceeding 500°C.

[0392] Pyrolysis methods for producing mixed plastic waste containing hydrocarbon condensates require a first pyrolysis reactor (plus an optional preheater) at a relatively low temperature but high load, and a second pyrolysis reactor (plus an optional coker) at a higher temperature but lower load. Therefore, a higher-temperature, lower-quantity molten salt stream can be matched to the second pyrolysis reactor, and a lower-temperature, higher-quantity molten salt stream can be matched to the first pyrolysis reactor, thereby optimizing efficiency.

[0393] Therefore, the total number of solar receivers in the dual-loop embodiment using molten salt according to the invention is 980. Conversely, for the same load, the number of solar receivers using a single loop with molten salt is 1050, about 7% more. This not only means greater installation and operating costs, but also (obviously) requires more land.

Claims

1. A method for producing at least one pyrolysis oil from a substantially plastic material, the method comprising the steps of: a) The first heat transfer fluid (F1) is heated to a temperature (T1) between 400°C and 520°C by solar radiation; b) The second heat transfer fluid (F2) is heated to a temperature (T2) higher than the temperature (T1) by solar radiation; c) The first pyrolysis reactor (R1) is heated by the first heat transfer fluid (F1); d) The second pyrolysis reactor (R2) is heated by the second heat transfer fluid (F2); e) Feeding at least one substantially plastic material (M1) into the first pyrolysis reactor (R1); f) The substantially plastic material (M1) is held in the first pyrolysis reactor for a residence time of at least 2 minutes and in any event sufficient to produce a gaseous fluid (M2) containing hydrocarbons; g) The fluid (M2) containing hydrocarbons in a gaseous state produced in the first pyrolysis reactor (R1) is fed into the second pyrolysis reactor (R2); h) The gaseous fluid (M2) is held in the second pyrolysis reactor (R2) for a residence time of at least 10 seconds; i) Completely or partially condense the gas leaving the second pyrolysis reactor (R2) to form at least one liquid containing hydrocarbons having a standard boiling point of not less than 25°C.

2. The method for producing at least one pyrolysis oil from essentially plastic materials according to claim 1, wherein the first and second heat transfer fluids (F1, F2) are substantially completely recycled.

3. The method for producing at least one pyrolysis oil from essentially plastic material according to claim 2, wherein the recirculation of the first heat transfer fluid (F1) forms a first heat transfer fluid loop ("warm loop"), and the recirculation of the second heat transfer fluid (F2) forms a second heat transfer fluid loop ("hot loop").

4. The method for producing at least one pyrolysis oil from a substantially plastic material according to claim 3, wherein the first heat transfer fluid circuit comprises steps a) and c) and the second heat transfer fluid circuit comprises steps b) and d).

5. A method for producing at least one pyrolysis oil from a substantially plastic material according to any one of claims 1 to 4, said method further comprising the following steps: j) The first heat transfer fluid (F1) from step c) is stored in a storage tank ("cold storage tank") before it is used in step a); k) The second heat transfer fluid (F2) heated in step b) is stored in a storage tank ("heat storage tank") before it is used in step d).

6. A method for producing at least one pyrolysis oil from a substantially plastic material according to any one of claims 1 to 5, wherein the first heat transfer fluid (F1) is identical in composition to the second heat transfer fluid (F2).

7. The method for producing at least one pyrolysis oil from a substantially plastic material according to claim 6, the method further comprising the following steps: l) The first heat transfer fluid (F1) heated in step a) is stored in a storage tank ("warm storage tank") before it is used in step c), and the separate second heat transfer fluid (F2) cooled in step d) is stored in a storage tank ("warm storage tank") before it is used in step b).

8. A method for producing at least one pyrolysis oil from a substantially plastic material according to any one of claims 1 to 6, said method further comprising the following steps: m) The first heat transfer fluid (F1) heated in step a) is stored in a storage tank ("warm storage tank A") before it is used in step c); n) The second heat transfer fluid (F2) cooled in step d) is stored in a storage tank ("warm storage tank B") before it is used in step b).

9. A method for producing at least one pyrolysis oil from a substantially plastic material according to any one of claims 1 to 8, said method further comprising the following steps: p) Prior to step e), the essentially plastic material is heated by a first heat transfer fluid (F1).

10. A method for producing at least one pyrolysis oil from a substantially plastic material according to any one of claims 1 to 9, said method further comprising the following steps: o) The liquid, solid, or semi-solid residue (carbon) from the pyrolysis of step f) is heated by a second heat transfer fluid (F2) and optionally by a gas heater, by resistance (Joule effect), and combinations thereof.

11. The method according to claim 9, wherein the substantially plastic material in step p) reaches a temperature between 120°C and 430°C, preferably between 150°C and 320°C, even more preferably between 180°C and 220°C, and wherein the average residence time in step p) is preferably less than 20 minutes, even more preferably less than 4 minutes, and especially less than one minute.

12. The method according to claim 10, wherein in step o), the charcoal 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 at least 5 minutes, preferably between 15 and 180 minutes, more preferably between 30 and 120 minutes.

13. The method according to any one of claims 1 to 12, wherein the first and second heat transfer fluids (F1, F2) are preferably molten salts having a melting temperature of up to 340°C, more preferably up to 270°C, and even more preferably up to 240°C.

14. The method according to claim 13, wherein the molten salt is a molten salt of Group IA or Group IIA of the periodic table, preferably sodium nitrate, sodium nitrite, potassium nitrite, potassium nitrate, lithium nitrate, calcium nitrate, or a mixture thereof.

15. The method of claim 13, wherein the molten salt is a nitrate / nitrite mixture, particularly a mixture of potassium nitrate and sodium nitrate, preferably a "sun salt", with sodium nitrite and calcium nitrate optionally added.

16. The method of claim 8, wherein the first heat transfer fluid (F1) is different in composition from the second heat transfer fluid (F2).

17. The method of claim 16, wherein the first heat transfer fluid (F1) has a lower melting point than the second heat transfer fluid (F2), and preferably, the first heat transfer fluid (F1) has a melting point of up to 180°C, or even more preferably up to 150°C.

18. The method according to any one of claims 1 to 17, wherein the temperature difference between the temperature T2 in step b) and the temperature T1 in step a) is at least 10°C, more preferably between 30°C and 300°C, and even more preferably between 60°C and 250°C.

19. The method according to any one of claims 1 to 18, wherein the heating in steps a) and b) is performed by a solar collector assembly comprising at least one of a parabolic trough, a linear Fresnel, or a combination thereof.

20. The method of claim 19, wherein the concentration coefficient of the at least one solar collector assembly in step b) is higher than that of the at least one solar collector assembly in step a).

21. The method according to any one of claims 1 to 20, wherein the substantially plastic material in the first pyrolysis reactor (70) reaches a temperature of 330°C to 580°C, preferably 340°C to 540°C, more preferably 360°C to 500°C, more preferably 380°C to 480°C, and even most preferably 410°C to 450°C, and wherein the temperature difference between the second pyrolysis reactor (71) and the first pyrolysis reactor (70) is at least 10°C, preferably between 30°C and 300°C, more preferably between 60°C and 250°C, with the additional condition that this temperature is between 400°C and 650°C, preferably between 440°C and 550°C, more preferably between 460°C and 530°C.

22. An apparatus for producing at least one pyrolysis oil from a substantially plastic material, said apparatus comprising: A) A first pyrolysis reactor (70), the reactor having at least one inlet for feeding substantially plastic material, an outlet for removing at least one gaseous effluent, and a jacket and / or coil having at least one inlet and one outlet for a heat transfer fluid; B) A second pyrolysis reactor (71) having at least one inlet for feeding at least one gas stream from the first pyrolysis reactor (70), an outlet for removing at least one gaseous effluent, and a jacket and / or coil having at least one inlet and one outlet for a heat transfer fluid. C) A first solar collector assembly (61) comprising a first solar receiver, preferably composed of a tube receiver, the first solar receiver comprising at least one inlet and one outlet for the heat transfer fluid, wherein the solar collector assembly is capable of delivering concentrated solar radiation to the first solar receiver, the receiver being configured to heat the heat transfer fluid. D) A second solar collector assembly (62), the assembly comprising a second solar receiver preferably composed of a tube receiver, the second solar receiver comprising at least one inlet and one outlet for the heat transfer fluid, wherein the solar collector assembly is capable of delivering concentrated solar radiation to the second solar receiver, the receiver being configured to heat the heat transfer fluid; E) First storage tank (63, "cold storage tank"), the first storage tank collects low-temperature heat transfer fluid, the first storage tank (63) is fluidly connected to receive the heat transfer fluid from the first pyrolysis reactor (70) and send the heat transfer fluid to the first solar collector assembly (61). F) A second storage tank (64, "warm storage tank"), which collects a heat transfer fluid at a moderate temperature, is fluidly connected to receive the heat transfer fluid from the first solar collector assembly (61) and send the heat transfer fluid to the first pyrolysis reactor (70). G) A third storage tank (65, "heat storage tank") that collects a high-temperature heat transfer fluid, the third storage tank (65) being fluidly connected to receive the heat transfer fluid from the second solar collector assembly (62) and send it to the second pyrolysis reactor (71); H) A condenser (72) having at least one inlet for a hydrocarbon-containing gas stream and an outlet for condensing liquid, the condenser being capable of at least partially condensing the hydrocarbon-containing gas stream; The first solar collector (61) is fluidly connected to the first storage tank (63) at one end of the first solar receiver and the second storage tank (64) at the other end of the first solar receiver; and the second solar collector (62) is fluidly connected to the second storage tank (64) at one end of the second solar receiver and the third storage tank (65) at the other end of the second solar receiver; and the condenser (72) is fluidly connected to the second pyrolysis reactor (71) so as to partially condense the pyrolysis vapor produced by the first pyrolysis reactor and the second pyrolysis reactor.

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