Pyrolysis method for the production of pyrolysis oil suitable for closed-loop recycling, related equipment, products and uses thereof

Abstract

The present invention relates to the treatment of plastic materials for use in chemical recycling processes to strengthen substantially plastic materials destined for waste. Specifically, the present invention relates to (a) providing a substantially plastic material to a pyrolysis reactor; (b) subjecting the material in the pyrolysis reactor to a temperature of between 330°C and 580°C in the substantial absence of oxygen and at a pressure between atmospheric and 13 bara; (c) maintaining the material in the pyrolysis reactor for a time sufficient to produce a gaseous effluent; (d) partially or completely condensing the gaseous effluent to form at least one fluid that is liquid at 25° C. and that contains at least 10% by weight of hydrocarbons, based on the weight of the substantially plastic material provided; (e) carrying out an evaluation of at least one property "Px" of the liquid condensed from said effluent in gaseous state by at least one measurement "Ax" of the spectrum of transmission, reflection or transflectance of the condensed liquid; (f) adjusting at least one process parameter "Ox" according to the evaluation of the at least one characteristic "Px", (g) iteratively repeating steps (e) and (f) to maintain at least one characteristic "Px" substantially constant over time. The present invention relates to a method for pyrolyzing a substantially plastic material to obtain hydrocarbons which are liquid at at least 25° C., comprising:

Description

[Technical field]

[0001] The present invention relates to the treatment of plastic materials for use in chemical recycling processes to strengthen substantially plastic materials destined for waste.

[0002] In particular, the present invention relates to a pyrolysis process for producing pyrolysis oil suitable for closed cycle recycling of plastics, products thereof and uses thereof.

[0003] The process of the invention refers in particular to a pyrolysis process capable of treating plastic materials of non-constant and / or non-uniform composition.

[0004] Advantageously, the present invention can be applied to process substantially plastic pre-processing materials in a sorting plant, where certain types of plastics are identified and separated as individual polymers.

[0005] In this way, the fraction that can be recovered as a single polymer can be reused as such (by so-called "mechanical" or "physical" recycling), and only the part that cannot be recovered as a single polymer is subjected to pyrolysis. After pyrolysis, hydrocarbons are produced, which undergo further processing such as steam cracking to produce polymerizable monomers to form plastics again. This closes the plastic cycle and realizes the so-called "closed loop recycling".

[0006] Recovery of said substantially plastic materials, especially the residue after sorting, is particularly difficult given that, once those that can be recovered as single polymers (e.g., polyethylene and polyethylene terephthalate) have already been selected, the residue is highly diverse and also contains non-plastic materials that are difficult to recover.

[0007] The method, device and process disclosed in the present invention, which teach an innovative way of analyzing said essentially plastic material, which is itself very heterogeneous, and carrying out pyrolysis according to the results of the analysis carried out, therefore makes it possible to effectively close the plastic cycle (and thus recover said residues by "chemical" methods). [Background technology]

[0008] There are numerous articles and patent applications relating to methods for the pyrolysis of plastic materials, but only a few disclose measurement systems for the products obtained and their use for controlling the pyrolysis reaction.

[0009] For example, WO 1991 / 015762 describes a method for calculating the different components of a hydrocarbon compound using short infrared spectroscopy, in particular PLAN (molar content of paraffins, isoparaffins, aromatics, naphthenes and olefins), and for each component of the PLAN, a wavelength interval is selected for measurement. From this evaluation, certain properties such as the octane number can be predicted. This patent does not mention pyrolysis processes.

[0010] Finally, there are several patents and scientific papers that relate to pyrolysis methods carried out at pressures other than atmospheric.

[0011] EP 2 348 254 describes a "zero-emission" pyrolysis process carried out at 10-15 bar and simultaneously supplying pure oxygen.

[0012] Spanish Patent No. 2389799 (Patent Document 3) discloses a method for the production of diesel oil (C13-C40). The first stage is thermal and the second stage is catalytic and in the presence of hydrogen. The feedstock is preferably a polyolefin. It may contain polystyrene but preferably contains less than 10% of other plastics such as PVC or PET.

[0013] There are several inventions that generalize pyrolysis under reduced pressure (below atmospheric pressure), such as WO 2013 / 187788 (Patent Document 4), WO 02 / 31082 (Patent Document 5), and EP 2184334 (Patent Document 6).

[0014] According to an analysis of the prior art, the measurement of properties on a hydrocarbon product by infrared spectroscopy has been used to determine its properties useful for application purposes (e.g., octane number) and / or useful for adjusting subsequent conversion processes.

[0015] Pyrolysis processes are also known that operate under conditions of residence time, temperature and pressure different from atmospheric pressure, for different types of input feedstocks and for different types of reactors. It is somewhat difficult to draw general lessons from this literature. Indeed, given the complexity of the methods and the diversity of the solutions offered, it is difficult to identify general lessons.

[0016] However, there is no known method by which process parameters can be adjusted in a linear manner to keep certain properties of the resulting pyrolysis oil, in particular the viscosity and refractive index, constant as the composition of the starting material changes.

[0017] Furthermore, there is no case in which the feedstock fed to the pyrolysis process has a non-constant composition, i.e. a composition that changes over time, and there is no teaching of how to modify the process in order to keep the resulting product constant in terms of properties such as viscosity and refractive index.

[0018] In addition, advantageously, said evaluation is not known to have been carried out on fluids obtained by partial condensation of the products directly at the outlet of a pyrolysis reactor.

[0019] Finally, refractive index and viscosity are not known to be optimal target parameters for identifying hydrocarbon compounds suitable for steam cracking to regenerate monomers useful for closing the plastics cycle.

[0020] Instead, the substantially plastic material remaining after the selection and extraction of a single polymer has a highly variable and non-uniform composition, since it is by its very nature composed of multiple types of plastic material as well as non-plastic materials. These characteristics, especially in continuous or semi-continuous processes, can lead to considerable variability in the composition of the pyrolysis products, necessitating further processing to obtain a product of the desired composition.

[0021] Moreover, pyrolysis methods require a preselection of the plastics fed in order to reduce the amount of difficult-to-process plastics (PVC, PET, cellulose, polystyrene, etc.) and non-plastic materials, in favor of polyolefins instead (especially polyethylene and polypropylene). However, a large proportion of the polyolefins contained in the substantially plastic material is usually separated in the selection process and subsequently recycled as such, without pyrolysis. There is therefore an interest in treating under pyrolysis the residual fraction after sorting, which in addition to polyolefins contains significant amounts of other plastics and smaller amounts of non-plastic materials.

[0022] It is therefore desirable to have a method and associated apparatus capable of processing said substantially plastic material of non-constant composition, capable of producing a pyrolysis oil having properties such that it can be advantageously used in a subsequent process, such as steam cracking to produce monomers that can be used again to produce polymers, in order to close the recycling cycle ("closed loop (or closed loop) recycling"), said properties of said pyrolysis oil being controlled and falling within the ranges required for effective use in said subsequent process. [Prior art documents] [Patent documents]

[0023] [Patent Document 1] International Publication No. 1991 / 015762 [Patent Document 2] European Patent No. 2348254 [Patent Document 3] Spanish Patent No. 2389799 [Patent Document 4] International Publication No. 2013 / 187788 [Patent Document 5] WO 02 / 31082 [Patent Document 6] European Patent No. 2184334 Summary of the Invention

[0024] The applicant has been able to develop a method for the pyrolysis of substantially plastic materials to obtain hydrocarbons which are liquid at least at 25° C., by subjecting the substantially plastic material, which has a non-constant and non-uniform composition and optionally contains large amounts of components which are normally considered undesirable, to the pyrolysis process.

[0025] A method for substantially pyrolyzing a plastic material to obtain hydrocarbons that are liquid at least at 25° C., comprising the steps of: (a) providing a substantially plastic material to a pyrolysis reactor; (b) subjecting the material in the pyrolysis reactor to a temperature of between 330°C and 580°C in the substantial absence of oxygen and at a pressure between atmospheric and 13 bara; (c) maintaining the material in the pyrolysis reactor for a time sufficient to produce at least one effluent in a gaseous state within the pyrolysis reactor; (d) partially or completely condensing said discharge in gaseous state to form at least one fluid which is liquid at 25° C. and which contains at least 10% by weight of hydrocarbons, quantitatively relative to the weight of the substantially plastic material fed; (e) carrying out an evaluation of at least one property "Px" of the liquid condensed from said effluent in gaseous state by at least one measurement "Ax" of the spectrum of transmission, reflection or transflexion of said condensed liquid; (f) adjusting at least one process parameter "Ox" according to said evaluation of at least one property "Px", (g) iteratively repeating steps (e) and (f) so as to maintain said at least one characteristic "Px" substantially constant over time. Includes.

[0026] A first advantage of the method disclosed in this invention is that it allows the processing of virtually any plastic material, even those with highly varying compositions, without the need to stop the method when the type of material is changed.

[0027] A further advantage of the method disclosed in this invention is that, by incorporating a pre-sorting process, plastics can be recycled an unlimited number of times ("closed-loop recycling"), i.e. the material can be used and regenerated several times without losing its properties during the recycling process.

[0028] A further advantage of the process disclosed in this invention is the ability of the process to process virtually any plastic material including vinyl polymers (polyethylene and polypropylene), polyvinylaromatics such as polystyrene (PS) and their alloys, non-vinyl polymers such as polyethylene terephthalate (PET), and oxygen rich polymers (such as cellulose and said PET) without process problems such as fouling or clogging and with a high quality of said hydrocarbons that are liquid at 25°C.

[0029] A further advantage of the method disclosed in this invention is that it is capable of treating essentially plastic materials that also contain large amounts of components that are normally considered undesirable, such as paper and cardboard (cellulose) and polymers containing chlorinated or brominated compounds, e.g. polyvinyl chloride (PVC) and halogenated flame retardants.

[0030] A further advantage of the method disclosed in this invention is the ability of the method to handle plastic materials of substantially variable composition without fouling or clogging.

[0031] A further advantage of the method disclosed in this invention is the ability of the method to process essentially plastic material that is the residue that could not be separated and recycled in the sorting methods commonly applied to plastic waste.

[0032] A further advantage of the process disclosed in the present invention is the ability of the process to produce high quality pyrolysis oil in terms of the resulting composition, even when the substantially plastic material being processed has a non-constant composition, maintaining a substantially high quality of the liquid hydrocarbons produced at 25°C.

[0033] An advantage of the apparatus disclosed in this invention is that it can be operated continuously and for long periods of time without requiring interruptions for maintenance or cleaning.

[0034] A further advantage of the method and apparatus disclosed in the present invention is that the waiting time between the measurement of the spectrum "Ax" and its use in adjusting the process parameter "Ox" (by calculating the characteristic "Px") can be very short. In particular, said waiting time may be set to a value not exceeding 1 hour, preferably not exceeding 10 minutes, and more preferably between 1 and 60 seconds.

[0035] Low latency is desirable because the effect is faster process correction and therefore less off-target production, and also because in feedback control, phase lag is reduced and therefore control is more stable.

[0036] Thus, existing processes that do not use the method according to the invention are usually carried out under constant conditions and therefore essentially obliged to use a pre-controlled and substantially constant quality feed plastic material in order to obtain a relatively constant quality product. Sometimes, empirically, experience is gained regarding the optimal processing conditions as a function of the type of substantially plastic material. For example, substantially plastic material from a supplier is assumed to be of constant composition, so that over time an empirical processing recipe (temperature, residence time, flow rate, etc.) is developed and optimized for the substantially plastic material from a particular supplier.

[0037] Finally, it is also possible to carry out offline measurements of the pyrolysis oil produced and adapt the method recipe according to accumulated experience, however this has clear disadvantages since the turnaround time for laboratory analysis is necessarily too short.

[0038] It is therefore an object of the present invention to overcome or at least mitigate the disadvantages of the state of the art mentioned above.

[0039] The present invention also relates to a compound comprising at least 90% by weight of hydrocarbons relative to the total weight of the compound, having a refractive index, measured according to the method defined below, of 1.415 to 1.465 nD, preferably of 1.42 to 1.455, more preferably of 1.425 to 1.45, and a viscosity, measured according to the method defined below, of 0.7 to 1.2 cP, preferably of 0.8 to 1.1 cP, more preferably of 0.85 to 1.05 cP, and a tetrahydrofuran (THF) content equal to less than or equal to 1% by weight, preferably between 0.01% and 0.25% by weight, more preferably between 0.07% and 0.19% by weight, relative to the total weight of the compound.

[0040] Advantageously, the tetrahydrofuran in the compound has solvent properties that reduce fouling in the processes in which the pyrolysis oil produced is used, thus making it possible to reduce the "downtime" of cleaning systems that use said pyrolysis oil, for example making it possible to reduce the "downtime" of steam cracking plants that use said pyrolysis oil by 10%.

[0041] It has also surprisingly been discovered that the pyrolysis oil obtained from the process of the present invention is characterized by low amounts of benzoic acid.

[0042] Large amounts of benzoic acid are actually generally harmful in processes using pyrolysis oils, since benzoic acid is acidic and is produced in large amounts when the substantially plastic material fed to the process contains large amounts of non-vinyl polymers such as polyethylene terephthalate (PET).

[0043] Currently, various methods have been proposed both to recover benzoic acid downstream of pyrolysis and to reduce its production by catalytic conversion (e.g., Shouchen Du et al., "Conversion of Polyethylene terephthalate based waste carpet to benzene-rich oild through thermal catalytic and catalytic steam pyrolysis," ACS Sustainable Chem. Eng. 2016, 4, 5, 2852-2860, April 11, 2016, doi https: / / doi.org / 10.1021 / acssuschemeng.6b00450).

[0044] Conversely, the process of the present invention makes it possible to avoid such benzoic acid recovery processes and provides a pyrolysis oil that already contains low amounts of benzoic acid.

[0045] Advantageously, the pyrolysis oil of the invention has a benzoic acid content of less than or equal to 2% relative to the total weight of the pyrolysis oil, preferably between 0.01 and 1%.

[0046] It has also surprisingly been discovered that the process of the present invention is characterized by low production of certain non-linear alkenes.

[0047] Alkenes are known to be generally undesirable in pyrolysis oils because they promote fouling and reduce naphtha quality, as measured, for example, using the PONA or PIONA index.

[0048] Advantageously, the pyrolysis oil covered by the invention is characterized by an isobutene content (IUPAC name 2-methylpropene) of less than or equal to 0.55% relative to the total weight of the pyrolysis oil, preferably between 0.15 and 0.3%.

[0049] The invention also relates to the use of said compounds for feeding cracking plants, in particular steam cracking plants, to produce monomers which can be used in the synthesis of polymers.

[0050] According to a preferred method, the at least one property "Px" is refractive index ("RI") or viscosity ("VI").

[0051] According to a preferred method, called "multiple correlation", said at least one characteristic "Px" is present at least twice. According to a further preferred method, called "double correlation", said at least one characteristic "Px" is present twice.

[0052] According to this preferred dual correlation mode, the properties "Px" are preferably refractive index ("RI") and viscosity ("VI").

[0053] Preferably, said evaluation of at least one property "Px" by at least one measurement of a spectrum "Ax" is performed by measuring the spectrum "Ax" and by measuring the temperature of the liquid in which the measurement is performed.

[0054] Preferably, the reflectance spectrum of the substantially plastic material obtained in step (e) is from 4000 to 12000 cm -1More preferably, the range is 4500 to 10000 cm -1 More preferably, the range is 5000 to 9000 cm -1 is in the range.

[0055] Preferably, said at least one measurement of the spectrum "Ax" is in transmission or semi-transmission, more preferably in transmission.

[0056] Preferably, the "liquid condensed from the effluent in gaseous state" for which the spectral measurement "Ax" is performed is a liquid obtained by partial condensation of the effluent in gaseous state of the pyrolysis reactor. Hereinafter, the method is referred to as "method of controlling the effluent in gaseous state discharged from a reactor". In this embodiment, the partial condensation can preferably be obtained by cooling at least a part of the effluent in gaseous state. More specifically, the cooling can be achieved by passing a fluid at a lower temperature than the effluent in gaseous state, which fluid brings about at least partial condensation.

[0057] According to the method "Control of the gaseous effluent discharged from the reactor", preferably the gaseous effluent of the pyrolysis reactor, at least after partial condensation, on which the spectral measurement "Ax" is performed, is the pyrolysis vapor contained in the pyrolysis reactor.

[0058] Again, according to the "Control of the gaseous effluent discharged from the reactor", more preferably the gaseous effluent of the pyrolysis reactor, for which the measurement of the spectrum "Ax" is carried out after at least partial condensation, is the pyrolysis vapour contained in the pyrolysis vapour outlet duct from the pyrolysis reactor. More preferably, according to the latter method, the vapour is conveyed to an area where at least partial condensation takes place and the measurement of the spectrum "Ax" is carried out within 2 minutes, preferably between 1 and 60 seconds, after the vapour enters the reactor outlet duct.

[0059] According to one embodiment, also according to said method, the measurement is carried out online, or in-line, as better defined below, in this embodiment the online mode is particularly preferred.

[0060] Alternatively, the "liquid condensed from the effluent in gaseous state" on which the spectral measurement "Ax" is performed is the liquid condensed in step (d) of the method of the present invention.

[0061] In case the condensation referred to in step (d) is carried out in multiple stages, said "liquid condensed from said effluent in gaseous state" may be the condensate of any stage. Preferably, in this multi-stage mode, said "liquid condensed from said effluent in gaseous state" is the condensate of the last stage, i.e. the condensate produced at the lowest temperature.

[0062] Alternatively, in the case of multi-stage condensation, the "liquid condensed from the effluent in gaseous state" on which the spectral "Ax" measurement is performed is the liquid obtained from combining the condensates of each stage, excluding the condensate recycled in the pyrolysis reactor.

[0063] The partial or total condensation carried out in step (d) preferably condenses at least 50%, more preferably at least 75%, of the pyrolysis vapors.

[0064] The method of the invention preferably comprises obtaining at least one calibration curve "Cx" capable of correlating the spectrum of transmittance, trans-transmittance or refractive index of the hydrocarbon liquid obtained from pyrolysis with the value of at least one property "Px" of said hydrocarbon liquid. Preferably, the calibration curve "Cx" is obtained by applying a multivariate regression method. Preferably, said multivariate regression method is multiple linear regression (MLR), principal component analysis (PCR) regression or partial least squares regression (PLS). More preferably, the multivariate regression is a regression using partial least squares (PLS).

[0065] When measurements are performed in transmission or semi-transmission mode, preferably the optical path of the light is less than 25 mm, preferably between 3 and 18 mm, more preferably between 5 and 15 mm, most preferably between 7 and 11 mm.

[0066] The measurement "Ax" is preferably carried out using a probe. Preferably, the probe used for the measurement has a wavelength of at least 4000 to 12000 cm -1 More preferably, in the range of 4500 to 10000 cm -1 More preferably, in the range of 5000 to 9000 cm -1 The light emitted can have a wave number in the range of

[0067] (definition) In describing the present invention, unless otherwise specified, ranges of values ​​(eg, ranges of pressure, temperature, amount, etc.) should be considered to be inclusive of the extreme values.

[0068] In the description of the present invention, unless otherwise specified, percentages are to be understood as percentages by weight (i.e. by mass). The symbol "%" means percent and always percentage by weight (percent by mass).

[0069] In the description of the present invention, the term "comprising" also includes, as specific limiting examples, the meanings "consisting of" or "consisting in".

[0070] In describing the present invention, the terms "essentially consisting of" or "essentially consisting in" mean that the composition or formulation (a) necessarily contains the recited ingredients, and (b) is open to unrecited ingredients that do not materially affect the basic and novel characteristics of the composition.

[0071] In the context of this invention, a material is in the "molten state" at a given temperature if it is not in a solid state and its flow index (MFR, melt flow rate), measured according to ISO 1133-1:2011, exceeds 2 g in 10 min at that temperature under a load of 10 kg.

[0072] Therefore, in the description of the present invention, the "molten state" also includes the liquid state.

[0073] In the present description, the term "sample spectrum" refers to a spectrum obtained on a sample material. In the present description, the term "hydrocarbon that is liquid at 25° C." refers to a hydrocarbon compound that is in a liquid state at 25° C. and atmospheric pressure.

[0074] In the present description, pyrolysis oil refers to the products of pyrolysis that are in the liquid state at 25° C. and atmospheric pressure.

[0075] In the present description, the term "hydrocarbon liquid" refers to a liquid that contains at least 90% by weight of hydrocarbons, based on the total weight of the liquid.

[0076] In the present description, the term "pyrolysis vapors" refers to products produced during the pyrolysis process that are in the gaseous state within the pyrolysis reactor, i.e., under the temperature, pressure and composition conditions of pyrolysis.

[0077] In the present description, the term "pyrolysis residue" means products that are in the liquid, solid, or liquid and solid state in the pyrolysis reactor, or products that are in the liquid and / or solid state under the temperature, pressure and composition conditions of pyrolysis.

[0078] In the present description, unless otherwise specified, the term "value of a parameter or characteristic at most equal to a certain value X" means that the parameter or characteristic is equal to or less than X, and means that the parameter or characteristic is equal to or greater than X for at least the value of the parameter (characteristic) equal to the certain value X.

[0079] In the present description, unless otherwise specified, the term "yield in the production of a product" means the weight percentage of that product relative to the total products produced.

[0080] In the present description, unless otherwise specified, the term "substantially free of oxygen" means that the oxygen in the pyrolysis vapor is less than 2% by weight, preferably less than 0.8% by weight, more preferably 20 to 4000 ppm by weight, based on the total weight of the composition of said vapor.

[0081] Unless otherwise specified, in this specification, "parts" means parts by weight. "Weight" means mass, i.e. kg in SI units. [Brief description of the drawings]

[0082] [Figure 1] The predictive ability of the calibration curve "Cx" corresponding to the refractive index of the characteristic "Px" is shown for the 27 sample materials investigated, with the horizontal axis showing the "actual" refractive index values, i.e. the refractive index values ​​determined by primary analysis, and the vertical axis showing the refractive index values ​​calculated using the corresponding calibration curve "Cx" ("predicted values"). [Diagram 2] The predictive ability of the calibration curve “Cx” corresponding to the viscosity characteristic “Px” is shown for the 23 sample materials investigated, with the “true” viscosity values ​​from the primary and vertical analyses shown on the horizontal axis and the calculated viscosity values ​​(“predicted values”) using the corresponding calibration curve “Cx”. [Diagram 3] The predictive ability of the PLS (Partial Least Squares) regression of refractive index feature "Px" and calibration curve "Cx" corresponding to viscosity is shown. The number of principal components used (NC) is shown on the horizontal axis, the root mean square error in cross validation (RMSECV) is shown on the vertical axis, the measurement units correspond to the feature "Px", therefore the scale of the left vertical axis is [nD], i.e. refractive index units, and the scale of the right vertical axis is [cP], i.e. centipoise. [Figure 4]The 100 spectra obtained with the pyrolysis oil of the present invention are shown superimposed, with the horizontal axis showing wavenumber (unit: cm-1) and the vertical axis showing absorbance. [Diagram 5] 1 shows diagrammatically an apparatus according to the present invention for the pyrolysis of a substantially plastic material to obtain hydrocarbons that are liquid at at least 25° C. [Figure 6] 1 illustrates an embodiment of a split range control mode in accordance with the present invention. [Figure 7] 1 shows an example of an embodiment of a mode for in-line acquisition of the absorption spectrum of pyrolysis condensate vapor. [Figure 8] FIG. 8 is a cross-sectional view showing the same example of implementation of the mode of in-line acquisition of absorption spectra of condensed pyrolysis vapors shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0083] The present invention mainly comprises: (a) providing a substantially plastic material to a pyrolysis reactor; (b) subjecting the material in the pyrolysis reactor to a temperature of between 330°C and 580°C in the substantial absence of oxygen and at a pressure between atmospheric and 13 bara; (c) maintaining the material in the pyrolysis reactor for a time sufficient to produce at least one effluent in a gaseous state within the pyrolysis reactor; (d) partially or completely condensing said discharge in gaseous state to form at least one fluid which is liquid at 25° C. and which contains at least 10% by weight of hydrocarbons, quantitatively relative to the weight of the substantially plastic material fed; (e) carrying out an evaluation of at least one property "Px" of the liquid condensed from said effluent in gaseous state by at least one measurement "Ax" of the spectrum of transmission, reflection or transflectance of said liquid; (f) adjusting at least one process parameter "Ox" according to said evaluation of at least one property "Px", (g) iteratively repeating steps (e) and (f) so as to maintain said at least one characteristic "Px" substantially constant over time; Including, The method relates to a method in which the measurement of "Ax" is performed directly on the condensed liquid by a spectrometer or spectrophotometer.

[0084] The spectrum of step (e) is an absorbance spectrum and can be measured by a spectrometer in transmission (transmittance), semi-transmittance (semi-transmittance) or reflection (refractive index) mode.

[0085] In transmission spectroscopy, the radiation analyzed by the spectrometer is the fraction of the incident radiation that passes through the sample, i.e., the fraction that is neither absorbed nor reflected by the sample.

[0086] In transflectance spectroscopy, the radiation analyzed by the spectrometer is the fraction of the incident radiation that passes through the sample and is then reflected by a special reflecting screen placed in the measurement cavity along the path of the radiation beyond the sample; the radiation reflected from the screen passes through the sample a second time before reaching the spectrometer.

[0087] In reflectance spectroscopy, the radiation analyzed by the spectrometer is the fraction of the radiation reflected by the sample, usually mostly diffuse radiation.

[0088] Preferably, the spectrometer is a spectrophotometer, ie it comprises a system for quantitatively measuring light intensity.

[0089] There is no particular limit to the type of spectrometer or spectrophotometer used, for example, spectrometers equipped with a prism monochromator or a diffraction grating monochromator, or a Fourier transform spectrometer, known as FTIR, may be used.

[0090] The monochromator spectrometer may advantageously comprise an array of photodiodes (or photodiodes) ("photodiode array" or PDA, also known as "diode array"). Said spectrometer is also known by the term "DAS" (Diode Array Spectrometer) or PDAS (Photodiode Array Spectrometer). Alternatively, a sensor and a corresponding CCD (Charge Coupled Device) spectrometer may be used.

[0091] The sample of substantially plastic material to be measured is illuminated by a broad spectrum light source, i.e. a light source that includes all frequencies included in the range of wavenumbers to be measured.

[0092] The spectrum is preferably the visible spectrum, i.e. 12000-25000 cm -1 , near infrared (NIR), i.e. 4000-12000 cm -1 , and / or mid-infrared (MIR), i.e., 400-4000 cm -1 More preferably, the spectrum is in the range of 4000 to 12000 cm -1 , and more preferably 4500 to 10000 cm -1 , and more preferably 5000 to 9000 cm -1 The range is.

[0093] The detection probe receives a portion of the transmitted or reflected light from the material sample illuminated by the light source, which is then directed to a spectrum analyzer for measurement. Thus, the detection probe is usually optically coupled to the emission probe, i.e., the detection probe is positioned and oriented to receive the transmitted or reflected light emitted by the emission probe.

[0094] There are also integrated devices in which both the light-emitting and light-receiving probes can be built into the same device. This is especially the case for probes that operate in reflection or semi-transmission. However, in the case of transmission probes, there are generally two separate devices, usually placed at 180 degrees from each other and at a given distance from each other along the diameter of the pipe through which the fluid to be measured flows. In fact, in this way it is possible to establish a precise optical path, usually less than 20 mm, more preferably between 5 and 15 mm.

[0095] Advantageously, the apparatus for measuring at least one property "Px" of a hydrocarbon liquid can be used continuously and for extended periods of time. Thus, a preferred method of the present invention is a method for substantially pyrolyzing plastic materials in a continuous or semi-continuous batch.

[0096] The term "kept substantially constant over time" in relation to the characteristic "Px" means that the characteristic "Px" is kept in the vicinity of a target value or range of values. The width of the vicinity depends on the characteristic "Px". According to one embodiment, said vicinity is equal to or less than the maximum value between 15% of the target value and 15% of the change in the characteristic "Px" observed when the plastic material passes substantially under unchanged process conditions from a first composition comprising 100% polyethylene to a second composition comprising 65% polyethylene, 25% polystyrene, 5% cellulose and 5% polyethylene terephthalate. If said characteristic "Px" is the refractive index "RI", in a preferred embodiment the amplitude of said vicinity is equal to 0.02nD, more preferably 0.01nD. Thus, for example, if the target value of the refractive index is 1.43nD, according to said embodiment "kept substantially constant over time" means that the refractive index is preferably maintained between 1.42nD and 1.44nD, more preferably between 1.425 and 1.435nD.

[0097] When said characteristic "Px" is viscosity "VI", in a preferred embodiment said neighbourhood amplitude is equal to 0.2 cP, more preferably 0.1 cP.

[0098] According to one embodiment, the term "repeatedly repeating steps (e) and (f)" means that steps (e) and (f) are repeated at least once every hour, preferably at least once every 15 minutes, more preferably at least once every 10 minutes, specifically between 10 seconds and 5 minutes.

[0099] In order to apply the method according to the invention substantially to the control of the pyrolysis of plastic materials, it is necessary to have at least one calibration curve "Cx" which makes it possible to correlate the spectrum of transmittance, transtransmittance or refractive index of the hydrocarbon liquid resulting from the pyrolysis with the value of at least one property "Px" of said hydrocarbon liquid.

[0100] Preferably, said at least one property "Px" of said hydrocarbon liquid is refractive index ("RI") and / or viscosity ("VI").

[0101] The calibration curve can be obtained by a method known to those skilled in the art. The calibration curve can be obtained by a univariate regression method. Preferably, the calibration curve can be obtained by a multivariate regression method.

[0102] To obtain a calibration curve, for example, a number of hydrocarbon liquids may be prepared for use as calibration curve samples (hereinafter referred to as "sample materials"), each of which is subjected to at least one primary analysis capable of determining the value of said at least one property "Px".

[0103] In accordance with the present invention, the primary analysis of refractive index "RI" is measured using the following method: Instrument used: Anton Paar Abbemat 300 digital diffractometer, equipped with software version 1.30, wavelength 589.3 nm, measurement range 1.26-1.72 nD, accuracy ±0.0001 nD, resolution 0.00001 nD, temperature control resolution 0.01 °C, accuracy ±0.05 °C, stability ±0.002 °C.

[0104] The measurement procedure corresponds to the procedure indicated by the supplier, in particular in chapter 9 "Measuring" of the instruction manual "Instruction Manual and Safety Information Abbemat 300 / 500" provided with the device. In particular, the height to which the liquid is filled is 1 mm for a volume equivalent to approximately 1 mL, as stated in this instruction manual. The measurements were carried out at a set temperature of 20.00 °C.

[0105] According to the present invention, the primary analysis of viscosity "VI" is measured using the following measurement equipment and method: The device used for viscosity measurements is a Brookfield Ametek DVE-ELVTJO digital viscometer. The measurement also uses an "Enhanced UL Adapter" for low viscosity liquids, which also functions as a "container" since the temperature ranges from 1 to 65°C. Measurements were performed at a temperature of 28°C and a rotation speed of 100 rpm. Therefore, the "ELV" model does not match the "LV" model, which according to the instruction manual has a maximum rotation speed of 60 rpm. A spindle with code "00" is used. The injection volume is at least 16 mL (until the entire "spindle" is immersed and the notch is reached). The maximum is no more than 18 mL. The viscosity value is read after 90 seconds of operation. The unit of viscosity is centipoise (cP).

[0106] Thus, the refractive index and viscosity values ​​of pyrolysis oils and the relative ranges given in this invention are understood to refer to the equipment and measurement procedures indicated.

[0107] According to the invention, the number of sample materials used to define the calibration curve is at least equal to 5, more preferably at least equal to 10. In a particularly preferred embodiment, the number of sample materials is between 15 and 50.

[0108] Advantageously, it is possible to use different types of liquid hydrocarbons obtained from the pyrolysis of substantially plastic materials and processed under different operating conditions (residence time, temperature, pressure).

[0109] For example, the substantially plastic material used to prepare the sample hydrocarbon liquid may be a blend of polymers including polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyurethane, polyethylene terephthalate and cellulose in various ratios.

[0110] It is particularly preferred to use various substantially plastic materials originating from the plastic recycling chain, with the addition of up to 20%, preferably 1% to 10%, of said polymer. In this way, it has been found possible to generate a stable (or robust) calibration curve, i.e. valid even in the case of considerable variations in the composition of the substantially plastic materials fed to the pyrolysis reactor.

[0111] There is no particular limitation on the spectrum meter used. Preferably, the spectrum meter is a spectrophotometer. More preferably, the spectrophotometer is a Fourier transform (FTIR) or a diode array or a dispersive spectrophotometer.

[0112] In either case, the spectrum is usually obtained in digital form. In particular, the digital spectrum obtained usually includes spectral values ​​for discrete numerical wavenumbers, also called channels. Advantageously, for a diode array spectrophotometer, the channels may correspond to individual diodes.

[0113] Advantageously, the optical radiation reflected by the sample that is analyzed and collected by the detection system is expressed in wavenumbers (typically cm) of the incident radiation according to techniques known to those skilled in the art. -1 The refractive index can be elaborated in the form of a refractive index spectrum (R) or preferably absorbance (A) as a function of refractive index (R) or wavelength (typically expressed in nm). The absorbance (A) is calculated from the measured refractive index (R) according to the relationship A=log(1 / R), where "log" is the natural logarithm.

[0114] Once obtained, the calibration and measurement spectra may be pre-processed in a manner known in the art, for example to correct for spectral distortions due to baseline shifts, etc.

[0115] To determine a given calibration curve "Cx", the calibration spectra and the values ​​of the properties "Px" (which, as mentioned above, have already been determined or are in any case known for the sample material) are analyzed using known statistical-mathematical methods of univariate and / or multivariate linear regression or, more commonly, by applying machine learning (ML) models such as artificial neural networks (ANN), genetic algorithms (GA), fuzzy logic, particle swarm optimization (PSO) and combinations thereof.

[0116] Preferably, the multivariate linear regression method is selected from the following: multiple linear regression (MLR) method, partial least squares (PLS) method, principal component regression (PCR) method, and combinations thereof.

[0117] According to one method, the calibration curve resulting from application of the multivariate regression methods described above may be a linear combination of the absorbances or other quantities derived from the latter.

[0118] Thus, according to this method, for each sample spectrum, the following equation: TIFF2025501984000002.tif3659, where "M" is the number of sample spectra evaluated, "j" is the representative index of sample spectrum "j" performed for a particular sample material "k" (as mentioned above, preferably more sample spectra are evaluated for each sample material); "Px j ” is the value of the Px property of sample material “k” used to measure sample spectrum “j”, "i" is the channel number, "N" is the number of channels, that is, the number of distinct wave numbers that make up the spectrum. A jiis the absorption of channel i measured on spectrum j (at wavelength λ i absorbance), or some other quantity derived from absorbance. "For k i in the range 0 to N, i is the coefficient (Cx) of the calibration curve to be determined. (hereinafter referred to as the "linear regression equation")

[0119] Therefore, there are N+1 unknowns (coefficients k i ), there are M equations (one for each sample spectrum evaluated).

[0120] If the number of sample spectra, M, is greater than N+1 and there are no linearly dependent sample spectra (i.e., linear combinations of two or more other spectra), then mathematically, the coefficient k i It is possible to regress a system of M equations to obtain the value of . This is the multiple linear regression (MLR) method.

[0121] However, it is desirable to reduce the number of N+1 unknowns because many of the unknowns are not actually linearly independent. For example, the signal related to the absorption of the double bond of the carbon atom of ethylene has several harmonics ("overtones"), so the presence of this double bond increases the absorbance signal in different channels.

[0122] Therefore, in accordance with a preferred embodiment of the present invention, the number of unknowns can be reduced by using multivariate analysis.

[0123] According to a first method, the data on the absorption of the sample spectrum are subjected to a Principal Component Analysis (PCA). Preferably, they are extracted from 4 to 15 principal components, more preferably from 5 to 11 principal components.

[0124] The model was obtained using the linear regression equation described above, where "A ji " represents the value ("score") of principal component "i" for sample spectrum "j". This mode of application of PCA is called "Principal Component Regression" (PCR).

[0125] According to a further preferred method of the present invention, the absorbance and characteristic Px of the sample spectrum are j The absorbance data are subjected to partial least squares (PLS) regression.

[0126] In fact, the characteristic Px in the above regression j The use of information from the regressed parameters Px j This allows the determination of the principal components that are able to explain the maximum variation in

[0127] With regard to PCR, this method preferably extracts 4 to 15 principal components, and more preferably extracts 5 to 11 principal components.

[0128] The model is then obtained using the linear regression equation previously described, where "A ji " represents the value ("score") of principal component "i" for sample spectrum "j", this time obtained by PLS.

[0129] The calibration curve "Cx" obtained from the multivariate regression analysis (e.g., MLR, PCR or PLS) is then subjected to validation using a series of spectra generated in the same manner as the sample spectra used to determine the calibration curve "Cx", i.e., in the hydrocarbon liquid, a property "Px" that can be determined using primary analysis as described above.

[0130] The inventors have developed a so-called "rotational" mode that makes it possible to obtain calibration curves that are particularly effective for predicting the "Px" control parameters, in particular the refractive index "RI" and the viscosity "VI".

[0131] According to this method, (a) splitting the sample spectrum such that 1% to 40%, preferably 10% to 30%, of the spectrum (by number) is used for validation and the remainder is used for calibration; (b) performing a multivariate regression, preferably PLS or PCR, on the spectra selected for calibration and performing validation on the spectra selected for validation, and calculating the mean squared error for the feature "Px"; (c) again subdividing the sample spectra so that 1% to 40%, preferably 8% to 25%, of the spectra (by number) are used for validation and the remainder are used for calibration, and selecting spectra for validation from those not previously selected for validation; (d) repeating the multivariate regression on a new selection of spectra for calibration and repeating the validation on a new selection of spectra for validation; (e) Calculate a new loading matrix, where each element of the matrix corresponds to the average of the corresponding elements of the single loading matrices obtained in steps (b) and (d).

[0132] Once a calibration curve has been validated, it can be used to calculate values ​​of control parameters "Px", such as refractive index "RI" or viscosity "VI", and applied to spectra acquired in-line. If multivariate regression methods are used, it is possible to calculate from the discrete values ​​of absorbance the values ​​(scores) of the same principal components of PCA and / or PLS previously identified during the determination of the calibration curve "Cx" (i.e. using the same "loadings" matrix).

[0133] At the production stage (i.e. of the pyrolysis method according to the invention), the spectrum analyzer can be advantageously connected to a control system such as a computer, a computing server, a distributed control system (DCS), a programmable logic controller (PLC) or a field programmable gate array (FPGA).

[0134] Spectrum analyzers can perform spectral measurements in a very short time, typically less than one minute. The calculation of said at least one parameter Px from said at least one calibration curve Cx is also very fast and generally consists of a relatively small number of algebraic operations (for an electronic calculator). Also, control systems are very fast. Thus, the entire sequence of operations (from the analysis "Ax" to the calculation of the process parameter "Ox") can be performed in a very short time, less than one minute, or even in a few seconds.

[0135] According to the present invention, it is preferable to repeat acquisition of spectra at a high frequency, preferably at least 10 times per hour, more preferably at least 30 times per hour, even more preferably 60 to 3600 times per hour, and even more preferably 120 to 900 times per hour.

[0136] According to the invention, it is preferred to acquire a series of spectra in order to switch to a process controller to calculate the process parameter "Ox" and then calculate the average parameter Px.

[0137] Preferably, the substantially plastic material fed to the pyrolysis reactor is comprised of different plastic compositions, more preferably the different plastic compositions include at least high H / C index polymers, e.g. polyethylene, polypropylene, polyamide, polymethyl methacrylate, and low H / C index polymers, e.g. polystyrene, polycarbonate, polyethylene terephthalate.

[0138] Alternatively, or in combination, said composition of different plastics includes 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, cellulose.

[0139] Preferably, said substantially plastic material is characterized by an H / C index at least equal to 70, preferably between 80 and 98, and even more preferably between 85 and 96.

[0140] Preferably, said substantially plastic material is characterized by a Carbon Index at least equal to 55, preferably between 65 and 95, and even more preferably between 75 and 90.

[0141] The H / C (or hydrogen / carbon) index and the carbon index are calculated by the following formula: TIFF2025501984000003.tif3178Here, "atomic weight" means the total mass of the atoms shown in the material (in the case of "all", the mass of all atoms, i.e. the mass of the material).

[0142] The substantially plastic material may also include at least one non-plastic material in an amount of 0.01% to 10%, or 0.05% to 7.5%, or 0.2% to 5% by weight, based on the weight of the substantially plastic material. The non-plastic material may include at least one of paper, cardboard, wood, compost (as defined by IUPAC in "Glossary of Terms for Bio-Related Polymers and Applications (IUPAC Recommendations 2012)", Pure Appl. Chem., Vol. 84, No. 2, pp. 377-410, 2012, DOI 10.1351 / PAC-REC-10-12-04), metallic materials such as aluminum and iron, and / or inert materials.

[0143] The substantially plastic material may include inorganic fillers such as silica, titanium dioxide, talc, coke, graphite, carbon black, calcium carbonate, etc. In some embodiments, the fillers may be present in an amount of 0.01 to 10%, preferably 0.1 to 5%, based on the total weight of the substantially plastic material.

[0144] In some embodiments, the substantially plastic material has a final inorganic residue (ash) of at least 0.01%, preferably 0.1% to 20%, more preferably 0.4 to 12%, and even more preferably 1.1% to 7%, by weight of the substantially plastic material, as measured according to the methods described herein.

[0145] Said substantially plastic material may contain brominated and chlorinated additives used to render the plastic material non-flammable or in any case to impart flame retardancy, examples of said additives include hexabromocyclododecane, decabromodiphenyl oxide, polybrominated diphenyl ethers, and brominated polymers such as brominated styrene-butadiene copolymers or brominated polystyrene.

[0146] The substantially plastic material may also include non-halogenated additives, such as phosphorus and nitrogen compounds, which are used to render the plastic material non-flammable or otherwise render it flame retardant.

[0147] If the plastic material substantially contains one or more of the above mentioned materials or substances, the pyrolysis method according to the invention is not adversely affected.

[0148] "Non-constant composition" means that the composition varies between different production batches. Alternatively or in combination, the composition is not constant because even within the same batch there are variations in the composition, for example due to stratification of the materials. Indeed, during transportation, stratification can occur, which generally determines an increased concentration of heavier and / or smaller size or powdery plastics at the bottom and an increased concentration of lighter and / or larger size plastics at the top.

[0149] Alternatively, the substantially plastic material does not have a constant composition, since it is supplied by different manufacturers or suppliers, each of which may have different manufacturing specifications and / or different manufacturing processes, resulting in a different product.

[0150] Preferably, said substantially plastic material is recycled.

[0151] Preferably, the substantially plastic material also comprises a halogenated component in an amount of from 0.01% to 10% by weight, based on the weight of the substantially plastic material.

[0152] Preferably, said substantially plastic material is obtained by a sorting process of plastic material. More preferably, said substantially plastic material is a residue of the substantially plastic material, i.e. a substantially plastic fraction remaining after recovery of some plastics, i.e. after selective extraction of certain plastics from the substantially plastic material fed to the sorting process. The selective extraction comprises the extraction of substantially the same material of certain plastics (i.e. a single plastic). Usually, the sorting process allows the extraction of a substantially pure plastic stream (i.e. a single plastic stream) of polyethylene, polypropylene and polyethylene terephthalate components. In this preferred selection, the remaining substantially plastic material is the material resulting after extraction of said substantially pure plastics. This fraction is known in Italy under the term "Plas Mix" or "Plasmix" and is defined as "a set of heterogeneous plastics contained in post-consumer packaging and not recovered as individual polymers" (Article 1, draft law Parliamentary Act No. 4502 dated 18 / 05 / 2017).

[0153] This substantially plastic material may be further selected to eliminate non-recyclable materials or may be used as such. In particular, according to a preferred method, said substantially plastic material is optionally obtained from a process involving sorting of plastic materials as described above and pre-treated before being used in the pyrolysis method of the invention.

[0154] This pretreatment preferably includes washing to remove at least a portion of the organic matter, and preferably also includes, alternatively or in combination, the removal of non-organic solid particulates such as ferrous materials and rubble.

[0155] Fluids containing hydrocarbons obtained from pyrolysis and which are in a liquid state at 25°C are also called pyrolysis oils.

[0156] Preferred methods of the present invention According to a preferred method, said measurement of at least one property "Px" of the hydrocarbon liquid is carried out in an in-line or online mode on the vapors leaving the pyrolysis reactor after at least partial condensation or on the vapors contained therein, whereas an offline mode is excluded.

[0157] In the on-line mode, the measurement of the property "Px" is performed by taking a vapor sample to be measured by a bypass or from the pyrolysis reactor or downstream thereof (e.g. from the pyrolysis vapor outlet duct). The vapor sample to be measured is therefore at least partially condensed and the measurement of the property "Px" is performed on the condensate. Typically, the condensed sample and the remaining vapor are returned to the pyrolysis reactor or downstream thereof.

[0158] In contrast, in the in-line mode, the measurement of the property "Px" is performed on the condensate of the main stream of pyrolysis vapors, i.e., not by bypass. Thus, in the in-line mode, the measurement is performed directly inside the pyrolysis reactor, after at least partial condensation, or directly inside the vapor outlet duct from said pyrolysis reactor.

[0159] Said at least partial condensation can be achieved by any method known in the art. Advantageously, it can be carried out using a coil in which a fluid is placed at a temperature at least lower than the condensation temperature of 50% by weight of the hydrocarbon liquid to be measured. According to an alternative method, said partial condensation can be carried out by wall cooling, this wall being, in the case of on-line mode, the wall of the duct through which the vapors to be condensed flow or of the vessel through which said vapors are passed and through which liquid accumulates, again, in the case of in-line mode, the same wall of the reactor or the wall of the pyrolysis vapor outlet duct from said pyrolysis reactor.

[0160] According to the invention, it is also preferred that the probe performing the measurement is fully flooded. By "fully flooded probe" it is meant that the level of the condensed hydrocarbon liquid must be greater than the level of the probe, whereby all of the light detected by said probe has passed, at least partially, through said condensed hydrocarbon liquid. By providing a weir it is possible to ensure that the level of the hydrocarbon liquid is always maintained above the level of the probe, regardless of the condensation capacity.

[0161] According to one embodiment of the invention, the evaluation of the characteristic "Px" is carried out online, the measured steam being taken from the reactor or from the pyrolysis steam outlet duct. Particularly preferred are the following: A mode in which the pyrolysis vapor stream is removed from the pyrolysis reactor through a pyrolysis vapor outlet duct; The removed steam stream is sent to a condenser to condense at least 50%, preferably at least 75% of the steam. The spectrum "Ax" is the mode measured on the condensate (preferably the lower part of the condenser which serves as a liquid storage volume), The steam is sent to the pyrolysis reactor or to the pyrolysis steam outlet duct or to the remaining pyrolysis steam before condensation in step (d) of the method, whereby the pyrolysis steam is resynthesized; preferably, the steam is sent to the remaining pyrolysis steam before condensation; The liquid is preferably fed by gravity to the pyrolysis reactor or to the pyrolysis vapor outlet duct, thus returning the liquid to the mainstream. Alternatively, instead of gravity reflux, a pump can be used for reflux.

[0162] According to another embodiment, the measurement of the characteristic "Px" is carried out in-line. In a preferred method for the in-line mode, the measurement is carried out on the condensate in a section of pipe intervening between the outlet of the vapors from the pyrolysis reactor and the duct carrying said vapors to the next unit (for example a second reactor or a condenser). Advantageously, in this way it is possible to carry out a thorough cleaning of the partitions in which the condensation of the vapors takes place. Preferably, in this method, the pipe section corresponding to the vapor outlet has less or even no insulation, allowing to condense a part of the vapors by transferring heat to the surrounding environment, at a much lower temperature than the pyrolysis vapors, typically without the need for jackets or coils. However, in another method, a cooling system such as jackets or coils is also provided to obtain a greater and more controlled condensation.

[0163] 7 and 8 show an embodiment in in-line mode in an intervening pipe section, with the details of the bulkheads and probes (92, 93, 94, 95) intentionally not drawn to scale relative to the diameter of the pipe (90) for greater visual clarity.

[0164] Referring to Figure 7: (70) is the pyrolysis reactor, (52) is the pyrolysis vapor stream exiting the pyrolysis reactor, (91) are opposing pipe sections, (90) is a pipe section interposed between the pipe (91) carrying the pyrolysis vapors and the reactor (70), (92) is an L-shaped angular profile rigidly fixed to the section of pipe (90), (93) and (94) are probes for emitting and detecting the transmission spectrum, and (95) is a probe for detecting the temperature of the condensate.

[0165] Referring to Figure 8: (90) is the pipe section interposed between the pipes, (92) is the angle profile, (93) and (94) are the light-emitting probe and the light-receiving probe facing each other, (95) is the temperature detection probe, and D90 is the distance between (93) and (94), which is the optical path that light travels through the hydrocarbon liquid.

[0166] Vapors leaving the reactor (70) partially condense on the walls of the pipe section (90) (as a result of the jacket, cooling coils, or simply by reducing the insulation, as explained above). An angle profile (92) forms a partition that keeps the light emission, detection probes (93, 94) and temperature measurement probe (95) submerged. A weir allows excess condensed hydrocarbon liquid to fall back into the reactor.

[0167] According to one embodiment, the angular profile (92) includes holes that are small enough to prevent liquid from emptying during the process while facilitating gradual emptying of the liquid when the process is stopped. For example, between 1 and 10 holes with diameters between 1 mm and 10 mm can be used.

[0168] According to a preferred method, said probe capable of emitting light comprises one or more optical fibres. According to a further preferred method, said detection probe also comprises one or more optical fibres.

[0169] Preferably, the temperature of the condensed hydrocarbon liquid is measured and the detected value is used in the calculation of said property "Px". In this method, the temperature value is used both in the regression stage to determine said calibration curve "Cx" as an additional variable for performing the regression, and in the operational stage as an additional variable used to calculate the property "Px".

[0170] The means for measuring temperature may be any means known in the art, such as, for example, a thermocouple, thermal resistance (such as "PT100" or "PT1000") or infrared measurement.

[0171] Preferably, the substantially plastic material fed to the reactor in step (a) is at least partially brought to a molten state by heating in a so-called preheating device. The preheating device may be a single-screw extruder, a twin-screw extruder or an auger. The preheating device may comprise a degasser for venting water vapour and other gases that are generated, such as in particular hydrogen chloride (HCl).

[0172] For this purpose, it may be advantageous to supply the preheating device with additives capable of promoting the generation of hydrochloric acid or salting out in addition to the substantially plastic material. The additives are preferably composed of elements of groups IA and IIA. More preferably, they are oxides, hydroxides, carbonates, silicates and aluminosilicates of groups IA and IIA. More preferably, they are calcium oxide, calcium hydroxide, calcium carbonate, sodium oxide, sodium hydroxide, sodium carbonate, potassium oxide, potassium hydroxide, potassium carbonate and sodium aluminosilicate.

[0173] The preheating temperature may be 120-430° C., preferably 150-320° C., more preferably 180-220° C. The residence time in the preheating device is preferably less than 10 minutes, more preferably less than 2 minutes, especially preferably less than 1 minute. The maximum pressure reached by the plastics material substantially in the preheating device is preferably at least 2 bara, more preferably 5-300 bara, even more preferably 10-50 bara.

[0174] Thus, according to a preferred method of the process of the invention, said substantially plastic material in an at least partially molten state is obtained by means of a preheating device, preferably an auger or an extruder.

[0175] The process for pyrolysis of substantially plastic material to obtain hydrocarbons that are liquid at least at 25° C. may be carried out in batch, continuous and semi-continuous modes, in which the substantially plastic feedstock is continuously fed and the evolved vapours are continuously extracted while the solid residue is retained in the pyrolysis reactor.

[0176] When the amount of solid residue in the reactor rises above a certain threshold, or at predetermined intervals of time, for example every 2 to 10 days, the material contained in the reactor, and thus the solid residue, is removed.

[0177] Preferably, the reactor is operated in a continuous or semi-continuous mode, more preferably in a semi-continuous mode.

[0178] The pyrolysis process of the present invention is not limited to a particular type of reactor.

[0179] In particular, horizontal or vertical reactors, stirred or non-stirred, rotating reactors (kiln reactors) or screw reactors may be used.

[0180] Within a Continuously Stirred Reactor (CSTR), a completely packed reactor may be used, or a reactor with separate phases including a gas phase and possibly other phases such as liquid and produced solids (char), or a reactor with a free surface may be used.

[0181] Preferably, the reactor is a stirred reactor. Preferably, the reactor has a free surface, i.e. a surface that substantially separates the gas phase from the substantially non-gaseous phase. The substantially non-gaseous phase is, for example, a phase that includes solids, liquids, which also means, for example, molten material, such as substantially plastic material, that is fed. The substantially non-gaseous phase may in any case also include gas bubbles from the gas phase, for example vapors of the products of pyrolysis returning to the reactor.

[0182] The temperature to which the material is brought in the pyrolysis reactor is 330°C to 580°C, preferably 340 to 540°C, more preferably 360 to 500°C, even more preferably 380 to 480°C, and most preferably 410 to 450°C.

[0183] The temperature of the material in the pyrolysis reactor may be measured using any method known in the art. For example, it is possible to use thermocouples with opposing membranes aligned with the inner surface of the reactor to reduce fouling, thermocouples in wells for more precise measurements inside the reactor, thermocouples that measure the temperature of metal near the polymer wetted reactor surface, or non-contact measurement systems such as infrared. Multiple systems may be used simultaneously to increase reliability.

[0184] The temperature may be controlled by the action of thermal power introduced into the reactor. The thermal power may be introduced using any technique known in the art, such as a reactor fitted with a heating jacket through which a suitable heat transfer fluid flows, direct electrical heating by Joule effect, electrical induction heating, etc. Heating by microwaves is also possible. Heating by a heating jacket is particularly preferred.

[0185] If a heat transfer fluid is used, it may be a molten salt.

[0186] The residence time in reactors into which the plastic material enters substantially continuously (and therefore is not of the "batch" type) is understood as the volume occupied by the non-gaseous phase divided by the volumetric flow rate of the substantially plastic material at the inlet of the pyrolysis reactor (which can be calculated as the mass flow rate divided by the density of said material at the inlet of the pyrolysis reactor), whereas in batch reactors it is understood as the duration of the pyrolysis process.

[0187] In the pyrolysis method of the present invention, the residence time is preferably at least 30 minutes, more preferably 45 to 600 minutes, even more preferably 60 to 400 minutes, even more preferably 90 to 300 minutes, and most preferably 130 to 240 minutes.

[0188] According to a preferred method, the pyrolysis vapors emerging from the pyrolysis reactor are then passed through at least one condensation separator to recover at least those hydrocarbons that are liquid at 25° C. (as defined in the present invention).

[0189] The term condensation separator refers to any device capable of receiving a fluid in a gaseous state and removing sufficient heat from said fluid to produce at least a portion of a fluid in a liquid state. An example of a device is a coil condenser through which a heat transfer fluid flows that can remove heat from the gaseous fluid being treated.

[0190] Other methods for removing heat may also be used, for example, alternatively or in combination, the condensation separator may be fitted with a jacket through which the heat transfer fluid flows, capable of removing heat.

[0191] Advantageously, a flooded condenser may be used, which is partially immersed by the liquid phase produced, and the condensing power can be adjusted by varying the height of said liquid phase, since only the non-immersed coils can absorb calories from the vapors being condensed, thus effectively adjusting the power of the condenser.

[0192] Alternatively, the condensation separator may consist of a distillation column. In this case, the condensate is generated in the column condenser and flows back into the column by gravity or by a pump, condensing the vapors in the column. The use of a distillation column type condensation separator allows the concentration of heavy components in the liquid phase and light components in the vapor phase at each equilibrium stage, which also improves the fractionation of the vapors at the inlet, i.e., the separation of the high boiling components that are condensed from the low boiling components that remain in the vapor phase. Furthermore, the condensate that falls into the column scrubs the vapors in the distillation column. As a result, solid particles present in the incoming vapor are retained and are finally recovered in the liquid phase.

[0193] Multiple condensation separators can be used, preferably in series. Preferably, there are three condensation separators in series.

[0194] The at least one condensation separator can operate at a pressure substantially corresponding to the pressure of the pyrolysis reactor or at a different pressure, for example substantially at atmospheric pressure, if the reactor is operated under pressure. Any technique known in the art may be used to maintain the pressure in the pyrolysis reactor at a specified value. For example, according to a first method, the pressure can be maintained at a specified value by adjusting the heat extracted from a condensation separator placed downstream of the reactor and in fluid communication therewith. Alternatively, according to a second method, the pressure may be adjusted using a controllable pressure drop device placed downstream of the pyrolysis reactor and / or downstream of the at least one condensation separator, or according to a third method, by supplying an auxiliary gas (such as, for example, nitrogen). These methods may be combined as necessary.

[0195] Non-condensable gases, including auxiliary gases that may be used for pressurization, may be sent to a thermal oxidation system before being released to the atmosphere.

[0196] The pressure in the reactor is preferably maintained within the range between atmospheric pressure and 13 bara. More preferably, said pressure is maintained within the range of 1.1-8 bara. Even more preferably, said pressure is maintained within the range of 1.5-6 bara. Most preferably, said pressure is kept within the interval of 2.5-4 bara.

[0197] The pressure in the reactor may be measured according to any method known in the art, for example by using a pressure transducer installed in the reactor, or, according to a preferred method in this case, by using an inert gas such as nitrogen for the initial pressurization of the reactor. The pressure sensor may advantageously be placed in the injection duct of said inert gas, more preferably towards the inlet of the reactor.

[0198] Advantageously, the assessment of a property "Px" of said hydrocarbon liquid by said at least one measurement of a spectrum "Ax" is used to adjust at least one parameter "Ox" of the pyrolysis process.

[0199] Said at least one parameter "Ox" is preferably at least one of the following: pyrolysis pressure, pyrolysis temperature, residence time of the substantially plastic material in the pyrolysis reactor, flow rate of the substantially plastic material in the pyrolysis reactor, and ratio of flow rates between two or more substantially plastic materials fed to the pyrolysis reactor. This latter parameter is particularly useful when recycled plastic materials of different origin or composition are present. It is thus possible to obtain a constant quality of pyrolysis oil by dynamically and automatically adjusting the ratio of the various power supplies by the controller so that the characteristic "Px" of the pyrolysis oil produced is maintained within a predefined target value.

[0200] The at least one parameter "Ox" is more preferably at least one of the following parameters: pyrolysis pressure, pyrolysis temperature, and residence time of the substantially plastic material in the pyrolysis reactor. More preferably, the at least one parameter "Ox" is the pyrolysis pressure.

[0201] According to a first method, defined in this specification as "feedforward regulation", the set point of said at least one parameter "Ox" is calculated based on the evaluation of said at least one characteristic "Px", in particular on the determination of the value of said characteristic "Px".

[0202] Said calculation can advantageously be a simple formula: if there is a plurality of at least one characteristic "Px", said formula for the calculation of at least one parameter "Ox" can advantageously include a plurality of characteristics "Px".

[0203] The adjustment of the process parameter "Ox" can be performed by any means known in the art, for example by a controller capable of reading the value of said "Ox", comparing it with a set point and acting on at least one parameter of at least one system element (such as those already mentioned above) in order to zero the difference between said two values. For this purpose, any method controller can be used, such as a PID controller, fuzzy logic, particle swarm optimization (PSO) or neural networks, or a combination of these, such as a PID controller integrated with a fuzzy logic controller.

[0204] Preferably, said regulation is performed using a PID algorithm (proportional, integral, derivative) of position (Position PID) or velocity (Velocity PID) type.

[0205] According to a second, more preferred method, defined herein as "feedback regulation", the parameter "Ox" is dynamically adjusted so that the characteristic "Px" reaches a target value or range. In this method, said characteristic "Px" is fed back to the process parameter "Ox" for regulation. This feedback can be direct or in cascade. According to direct feedback, a regulator acts directly on a device having the effect of changing the process parameter "Ox". According to cascade regulation, the feedback of the regulator of said characteristic "Px" acts by changing the set point of the characteristic "Px" of a second regulator, which is a regulator of the process parameter "Ox", acting on said device having the effect of changing the process parameter "Ox".

[0206] Depending on the process parameter "Ox" and the characteristic "Px", the action may be direct (i.e. coincident) or inverse (i.e. inconsistent). In the case of direct action, an increase in "Ox" corresponds to an increase in "Px", in the opposite case, an increase in "Ox" corresponds to a decrease in "Px" and vice versa. If it is not known in advance whether it is a direct or inverse action, it is sufficient to carry out a preliminary test, and if the action set in the controller is set in the wrong direction, the regulator will quickly diverge (or diverge), since the corrective action will increase the error rather than reduce it. In this case, it is sufficient to reverse the action.

[0207] If "Ox" is the pressure of the reactor, said device having the effect of varying the process parameter "Ox" may be one or more of the disclosed devices serving to control the pressure in the reactor. These include, for example, said controllable pressure drop device located downstream of the pyrolysis reactor and / or downstream of said at least one condensation separator, or a valve regulating the flow rate of an auxiliary gas or fluid in the condensation separator jacket.

[0208] In contrast, if "Ox" is the temperature in the pyrolysis reactor, the device having the effect of varying the process parameter "Ox" may be a device adjusting the flow rate of the heat transfer fluid in the reactor jacket, or a device adjusting the temperature of the heat transfer fluid, or, in the case of electric or microwave heating, a device adjusting its power.

[0209] Preferably, said property "Px" is the refractive index "RI" and / or the viscosity "VI" of the pyrolysis oil produced by the process of the present invention.

[0210] When the characteristic "Px" is the refractive index "RI" of the pyrolysis oil, according to the aforementioned "feedback" regulation mode, the target value of the characteristic "Px" (i.e., the refractive index "RI") is set to a value between 1.415 and 1.465nD, preferably between 1.42 and 1.455, and more preferably between 1.425 and 1.45.

[0211] When the characteristic “Px” is the viscosity “VI” of the pyrolysis oil, according to the above-mentioned feedback regulation mode, the target value of the characteristic “Px” (i.e., the viscosity “VI”) is set to a value of 0.7-1.2 cP, preferably 0.8-1.1 cP, and more preferably 0.85-1.05 cP.

[0212] Generally, the method that gives the best results is one in which the property "Px" is the refractive index and the process parameter "Ox" is the reactor pressure.

[0213] Preferably, the pyrolysis oil obtained from the process of the present invention is a compound containing more than 90% by weight of hydrocarbons, based on the total weight of the compound.

[0214] Preferably, the pyrolysis oil obtained from the process of the invention has a tetrahydrofuran (THF) content equal to or less than 1% by weight, preferably between 0.01% and 0.25% by weight, and even more preferably between 0.07% and 0.19% by weight, relative to the total weight of the compounds.

[0215] Preferably, the product obtained according to the invention, liquid at 25°C condensed by the pyrolysis vapours (i.e. pyrolysis oil), has a C5-C12 fraction at least equal to 35% and at the same time a C21+ fraction (hereinafter referred to as "C21+") at most equal to 3.5%.

[0216] Preferably, the yield of C5-C12 obtained according to the present invention is at least 30%, whereas the yield of C21 and above is at most 3%.

[0217] FIG. 5 is a diagram showing an example of a device for the method of the present invention, comprising: a reactor (70) for the pyrolysis of a substantially plastic material (54) producing pyrolysis vapors (52) and a solid residue (53) and optionally receiving an auxiliary gaseous fluid (51) for maintaining pressure within the reactor; a second reactor (71) for converting the pyrolysis vapors (52) exiting the pyrolysis reactor (70); a first pressure control device (72), such as a valve, acting in feedback on the pressure value (80) measured in the pyrolysis reactor (70); a first condenser (73) in which the condensate (60) is partially returned to the pyrolysis reactor (70); a second condenser (74) that receives the vapor (57) exiting the first condenser (73) and produces a second condensate (61) and vapor (58); a third condenser (75) that receives the vapor (58) from the second condenser (74) and produces a third condensate (62) and a non-condensed vapor or residual gas (59); A second device for feedback control of the pressure (76) with respect to the pressure value (80) measured in the pyrolysis reactor (70), for example a valve restricting the passage of the residual gas (59) leaving the condenser before sending the residual gas (56) to a unit capable of receiving it. is shown.

[0218] One aspect of the present invention is a method for producing a composition comprising the steps of: at least one reactor for substantially pyrolyzing the plastic material; at least one condensation separator that receives and at least partially condenses vapor from the at least one pyrolysis reactor; At least one device for measuring "Ax" the transmission, reflection or trans-transmission spectrum of the liquid condensed from said effluent in gaseous state; At least one system for evaluating at least one property "Px" of the liquid condensed from said effluent in gaseous state by at least said measurement "Ax", and for adjusting at least one process parameter "Ox" according to said evaluation of at least one property "Px". a) a device for the pyrolysis of a substantially plastic material to obtain at least hydrocarbons which are liquid at 25° C.,

[0219] According to one embodiment of the method, the effluent in gaseous state produced in step (c) may be further treated in a second reactor in a dedicated step (c2) before carrying out the partial or total condensation referred to in step (d). Preferably, this further treatment in step (c2) comprises bringing said effluent to a temperature between 400° C. and 650° C., preferably between 440° C. and 550° C., more preferably between 460° C. and 530° C., and keeping said effluent in said temperature range for a time equal to at least 10 seconds, preferably between 30 seconds and 6 minutes, more preferably between 1 minute and 4 minutes.

[0220] Preferably, step (c2) is carried out in the presence of a solid catalyst in contact with said effluent in gaseous state, more preferably said effluent in gaseous state is in relative motion with respect to said solid catalyst in contact with said effluent in gaseous state, said relative motion being at a speed at least equal to 10 m / s, more preferably between 20 and 300 m / s.

[0221] Example of an embodiment of pressure control according to the present invention FIG. 6 shows some examples of embodiments of pressure control according to the present invention, where a submerged (or flooded) type condensate separator (75) is shown with a level sensor (LT) and a level adjustment system by adjusting the opening of a valve (78) at the condensate outlet (62).

[0222] Referring to the figure, a pyrolysis reactor (70) receives at its inlet substantially the plastic material (54) and, optionally, an auxiliary gaseous fluid (51) and produces a solid residue (53) and pyrolysis steam that is directed to at least one condensation separator (75). The optional regulating valve (72) receives the pyrolysis steam from the pyrolysis reactor (70) and directs them to the condensation separator (75). The opening is regulated by a signal (85).

[0223] The condensate separator (75) of FIG. 6 is an immersed condenser, in which the condensate is condensed by passing a heat transfer fluid, which is cooler than the pyrolysis vapors, through a jacket or coil that is immersed in the lower part of the condenser and is arranged (e.g., by applying a jacket to the side walls of said condenser) in such a way that the portion of the jacket in contact with the vapor to be condensed varies depending on the level of the condensate.

[0224] An optional regulating valve (76) regulates the pressure by restricting the passage of the residual gas (59) before it is sent to the receiving unit.

[0225] An optional regulating valve (78) regulates the flow of condensate (62) and thereby the submersion level of the submerged condenser (75).

[0226] Optional regulating valve (77) regulates the flow rate of the auxiliary gaseous fluid entering the pyrolysis reactor (70).

[0227] The level controller (LIC) reads the level signal (83) of the immersed condenser (75) measured by the level sensor (LT) and adjusts the opening of the valve (78) by feedback so that the level (83) corresponds to a set point instruction (86) received from the PIC controller. Note that the set point instruction (86) is equal to 0 at the 100% level (i.e. maximum immersion = minimum condensing power) and equal to 100 at the 0% level (i.e. empty condenser = maximum condensing power).

[0228] The opening instruction (87) sent to the valve (76) is 0 if the valve is closed and 100 if the valve is fully open.

[0229] In contrast, the position command (84) sent to valve (77) operates in the reverse mode because valve (77) must open to increase reactor pressure (80) and close to decrease it.

[0230] The pyrolysis reactor pressure signal (80) may be the result of processing multiple pressure transducers; Additionally, it may be detected in the clean fluid being fed to the pyrolysis reactor near the outlet to said reactor so that the transducer membrane remains clean, as shown in the figure, where the pressure signal is taken in the conduit feeding the auxiliary gaseous fluid (51) to the pyrolysis reactor.

[0231] The pressure set point of the pyrolysis reactor (PS) may be set locally or manually, for example by setting a value at the plant's control panel, or may be set remotely or derived from an external setting signal.

[0232] The external signal is a setpoint (82) calculated by a feedback controller (AIC) which adjusts the setpoint (82) so that a parameter (AT; OUTPUT) representative of the quality of the product in liquid state obtained after condensation (62), measured by an analytical device either online or offline, reaches a target value.

[0233] A pressure controller (PIC) reads said pressure signal (80), compares it with a set point (PS) and acts on one of the regulating devices (84, 85, 86, 87) either individually or in combination, for example using a PID algorithm (Proportional, Integral, Derivative) with feedback, to minimize the error between the read signal (80) and the set point (PS). An example of said combined embodiment is obtained by using regulating devices (86) and (87) in split range mode.

[0234] Gas chromatographic analysis method for pyrolysis oil samples Pyrolysis oil samples were characterized by gas chromatographic analysis: qualitative identification of compounds was preliminarily performed using coupled gas chromatography-mass spectrometry (GC-MS) techniques, and quantification was performed by gas chromatography with flame ionization detection (GC-FID).

[0235] The following instrument parameters were used for the GC-FID analysis: GC: Agilent HP 7890 B with MPS autosampler Gerstel Column: HP-PONA Agilent Technologies J&W-50m-0.2mm-0.5μm; Carrier (H2): Constant flow rate of 1.1 mL / min Injector: 320°C, split 255:1, 3mm liner with glass wool (Ultra Inert) Detector: 360℃ Oven: Column temperature program: 20 °C 5 min, 2 °C / min to 70 °C 5 min, 2 °C / min to 160 °C 5 min, 2 °C / min to 320 °C 30 min (run time: 195 min).

[0236] Samples are analyzed using an arbitrary response factor of 1 for all compounds and the resulting concentrations are normalized to 100%.

[0237] Gas chromatographic analysis of wax samples. The term "wax" refers to the fraction remaining at the bottom after ultracentrifugation of the pyrolysis oil, as described below.

[0238] This fraction is analyzed with different methods to also identify higher molecular weight compounds.

[0239] In fact, such compounds may not be eluted and analyzed in a gas chromatographic analysis.

[0240] Prior to taking samples for GPC analysis, pyrolysis oils in Schott bottles were heated to 50°C and the contents homogenized (in some cases characterized by deposition and / or stratification of waxy compounds at room temperature or upon cooling). A few milligrams of sample in 1,2,4-trichlorobenzene (Baker) was melted hot (dissolved at 150°C for 1 h) with the addition of 10 μL of n-heptane (internal marker) to a concentration of approximately 1.8 mg / mL.

[0241] The analysis is as follows: High Temperature GPC-IR Polymer Char, A bench with 3 TSK gel HT2 columns with size (particle size) 13 μm and a pre-column; High temperature IR5 infrared detector provides absorbance signal proportional to the amount of methyl and methylene groups The chromatography was carried out on a chromatography system equipped with

[0242] The experimental conditions used were as follows: Eluent: 1,2,4-TCB stabilized with BHT Flow rate: 1mL / min Temperature: Pump 25°C, injector 150°C, column 150°C, detector 150°C Injection volume: 200μL Internal standard: n-heptane It is.

[0243] Gas chromatographic analysis of pyrolysis gases Pyrolysis gaseous effluent samples were sampled in 500 mL Swagelok cylinders, DOT type (i.e., regulated by the U.S. Department of Transportation - DOT), stainless steel type 304L, coated with PTFE to render the inner surface inert. The instrument used was an Agilent 490μ GC with three modules in parallel, each measuring only a certain class of compounds. Specifically: Module 1: 10m MS 5Å with heated injector and backflush Module 2: 10m PPQ with unheated injector Module 3: 10m CpSil-5CB with heated injector It is.

[0244] The instrument parameters used for each module are given below: Module 1: injector temperature: 110 °C, backflush: 30 s, injection time: 100 ms, column temperature: 45 °C, carrier gas pressure: 80 kPa, carrier gas: argon (basic for hydrogen analysis). Module 2: injection time: 15 ms, column temperature: 70 °C, carrier gas pressure: 180 kPa, carrier gas: helium. Module 3: injector temperature: 110 °C, injection time: 20 ms, column temperature: 70 °C, carrier gas pressure: 230 kPa, carrier gas: helium.

[0245] Each module analyzes only a few specific compounds: Module 1: Hydrogen, Oxygen, Nitrogen, Methane, CO. Module 2: CO2, ethylene, ethane, propylene, propane, propadiene, propylene, i-butane, i-butene, 1-butene, 1,3-butadiene, n-butane, trans-2-butene, cis-2-butene. Module 3: 1-butene-3-yno, 1,2-butadiene, i-pentane, 1,4-pentadiene, 1-pentene, n-pentane, 2-methyl-2-butene, 1,3-pentadiene, cyclopentene, n-hexane, methyl-1,3-cyclopentadiene, benzene, 3-ethylcyclopentene, methylcyclohexane, toluene, ethylbenzene, xylene.

[0246] Quantification is carried out by means of a calibration curve with an external standard consisting of two calibration cylinders of the following composition: Cylinder 1: PENTENE-2 (trans) = 0.1 mol%; PENTENE-2 (cis) = 0.1 mol%; PENTENE-1 = 0.1 mol%; PENTANE-n = 0.25 mol%; METHYL-2-BUTENE-2 = 0.2 mol%; ISOPENTANE = 0.5 mol%; HEXANE-n = 0.1 mol%; PROPYLENE = 20 mol%; PROPANE = 0.5 mol%; PROPADIENE = 0.5 mol%; METHANE = 20 mol%; ISOBUTENE = 1 mol%; ISOBUTANE = 0.5 mol%; HYDROGEN = 15 mol%; ETHYLENE = 30 mol%; ETHANE = 3 mol%; CARBON MONOXIDE = 1 mol%; CARBON DIOXIDE = 0.5 mol%; BUTEN-1 = 1 mol%; BUTEN-2(TRANS) = 0.5 mol%; BUTEN-2(CIS) = 0.5 mol%; BUTANE-n = 0.5 mol%; BUTADIENE-1,3 = 1.5 mol%; ACETYLENE = 0.5 mol%; Remainder 100%: NITROGEN. Cylinder volume [liters]: 40; Filling pressure [bar]: 6.29; Cylinder type: Aluminium. Cylinder 2: BENZENE = 0.0302 mol%; TOLUENE = 0.0323 mol%; METHYL CYCLOHEXANE = 0.0674 mol%; STYRENE = 0.0334 mol%; ETHYLBENZENE = 0.0339 mol%; Remainder 100%: HELIUM. Cylinder volume [liters]: 5; Filling pressure [bar]: 13.9; Cylinder type: Aluminium.

[0247] The following compounds were not included in the calibration cylinders. Therefore, for the calibration, similar enough compounds were used that have very similar response factors (the differences in this case are negligible): TIFF2025501984000004.tif99158

[0248] Thermogravimetric analysis (TGA) method for solid residues (chars) TGA analysis was performed on a TA Instrument model Q 500. Temperature calibration was performed using the Curie points of aluminium and nickel samples and weight calibration was performed using certified weights provided by TA Instrument with the analyzer. Samples were weighed out in amounts of 20-30 mg onto stainless steel sample holders and placed into the platinum crucible of the TGA analyzer along with the sample holder. The use of the stainless steel sample holder facilitates separation and recovery of the final residue (ash) while preserving the integrity of the platinum crucible. Samples were collected through three steps: A first step (pyrolysis under nitrogen atmosphere) in which the sample is heated at a controlled rate (v=10°C / min) to 800°C, starting from an initial temperature of 40°C; A second step (cooling under nitrogen atmosphere) starting from an initial temperature of 800 °C and cooling the sample at a controlled rate (v = 20 °C / min) to 400 °C; A third step (thermal oxidation in air atmosphere) in which the sample obtained from pyrolysis (step 1) is heated at a controlled rate (v = 20 °C / min) starting from a temperature of 400 °C up to 850 °C. is analyzed.

[0249] Integration was performed using Universal software (TA Instruments) and the following: STEP 1: Determine the temperature corresponding to the maximum peak of the derivative of weight loss with respect to temperature, and then measure the weight loss at various temperatures and the residue at 800°C. STEP 3: Weight loss at various temperatures, subject to determining the temperature corresponding to the maximum value of the peak of the derivative of the weight loss with respect to the residue at 850°C versus temperature. In STEP 3, the weight loss corresponds to one or more carbonaceous species of different allotropic states or particle sizes.

[0250] Method for determining the ash content (inorganic residue) of plastic materials 20 g of substantially plastic material was weighed into a crucible and placed in an oven (Heraeus model K1253, Tmax: 1250° C.) maintained with a nitrogen supply. The temperature was ramped up to 400° C. with a ramp of 5° C. / min and maintained at 400° C. for an additional hour. Air was then supplied instead of nitrogen and the temperature was again gradually ramped up to 850° C. with a ramp of 5° C. / min and maintained at 850° C. for an additional hour.

[0251] The remaining material was called ash and was weighed. The ash percentage was calculated as the weight of the residue relative to the amount of essentially plastic material initially weighed (20 grams). EXAMPLES

[0252] Some illustrative, but non-limiting examples of the present invention are given below.

[0253] raw material The use of virgin raw materials was deemed appropriate and the present invention is easily reproducible since its composition is known and constant, therefore, by preparing a suitable mixture of raw materials, it was possible to evaluate the effect of its independent variation on pyrolysis.

[0254] The virgin raw materials used were as follows: TIFF2025501984000005.tif134161

[0255] The polyethylene granules were mixed in the following ratios: 5.7% HDPE Eraclene BC82, 34.3% LLDPE Flexirene CL10, 60% Riblene FC20. This mixture is therefore the "PE" material used later.

[0256] The table below shows the atomic composition (by weight) of the materials used. TIFF2025501984000006.tif68158

[0257] The following mixtures were prepared using the ingredients listed (parts by weight): TIFF2025501984000007.tif88121

[0258] Additionally, four batches of recycled material were analyzed to determine the Hydrogen / Carbon Ratio (H / C Index) and Carbon Index (CI) along with a mixture of PATA and PATB. These two indices are calculated by performing elemental analysis and calculating said indices based on the formulas mentioned above. The recycled material was also analyzed using thermogravimetric analysis to determine the final inorganic residue (ash).

[0259] The results are as follows: TIFF2025501984000008.tif65155

[0260] Preparation of granulated polymer mixture Mixtures were prepared according to the composition tables given above (PATA, PATB).

[0261] In a Coperion ZSK 26 twin screw extruder, the mixture thus prepared was melted at 250 ° C, mixed with the mixing elements present in the extruder screw and passed through the extrusion die. The total residence time of the extrusion was less than 1 minute. The mixture of polymers thus obtained was then cooled in a liquid bath and granulated into granules with a diameter and length of about 3 mm. In this way, a mixture of granulated polymers PATA and PATB was produced.

[0262] DEVICE FOR DELIVERING A SUBSTANTIALLY PLASTIC MATERIAL IN AT LEAST PARTIALLY MOLTEN STATE - Patent application The device in question consists of a ZSK 26 rotating twin screw extruder with a screw length to diameter ratio equal to L / D=32. A feed section equipped with a hopper and a screw profile with conveying elements, A melting and mixing section in which kneading and mixing elements are used; The degassing section reduces the pressure in the polymer spindle, thereby reducing the diameter of the screw core, and provides an opening in the cylinder to connect it to a vacuum pump to suck out the gases that are generated. A pressure section that increases the diameter of the screw core; It is equipped with The extruder is equipped with a heating and cooling control system, which regulates the temperature of the barrel in each section of the extruder mentioned above, The extruder screw speed was kept high enough to keep the extruder hopper empty.

[0263] Two gravimetric dosing devices (or dosers) allow dosing at a defined flow rate: the PATA mixture was fed into a first feeder (or dispenser) and the PATB mixture was fed into a second metered dispenser.

[0264] In the extruder heating and cooling control system, the temperature set points of the extruder barrels were all set at 200°C.

[0265] Pyrolysis Device Used in the Pyrolysis Examples ("Device 1") The pyrolysis device used in the pyrolysis examples of the present invention was as follows: a thermostatic reactor equipped with flanges for feeding the material, a dip tube for the inlet of an inert gas (nitrogen), a nozzle for connection to a possible extruder for feeding the plastic material, a nozzle for discharging steam, and a nozzle for each thermocouple for measuring temperature and pressure, as well as two nozzles for level measurement by measuring the differential pressure between the two nozzles ("DP-cell"); a stirring system for said reactor, equipped with an anchor-type agitator, a breakwater and having a low rotation speed (tip speed of about 0.1 m / s); A flowmeter with a fine adjustment valve to adjust the inert gas inlet flow rate to the reactor; a pressure transducer located at the head of the reactor and a local pressure gauge reading the pressure of the gas in the reactor; 3 thermocouples for measuring the actual temperature located at the bottom of the reactor (one for control, the others for reading and checking) Level meter using "DP-Cell" A reactor temperature regulation system whose control parameters are suitably adjusted to ensure high thermal stability (temperature fluctuations of 5°C or less), reading the temperature value of one of three thermocouples and feeding it back to a thermostat system; a condenser for condensing the vapor exiting the reactor, the condenser being kept at -10°C by a refrigerant fluid flowing through a refrigeration unit at a controlled temperature; a regulating valve (hereinafter referred to as a pressure regulating valve) interposed between the reactor and the condenser; in fact, even if the flow rate of pyrolysis vapors produced is the same, the pressure drop varies with the stroke of the valve, and therefore, in a downstream device at substantially ambient pressure, the pressure in the pyrolysis reactor also varies; an inflatable balloon in gas-tight connection at the upper outlet of the condenser, designed to recover the non-condensed gaseous fraction; a receiving vessel in an airtight connection at the lower outlet of the condenser, designed to collect the condensed fraction, therefore in liquid form, and having an air hole connected to the upper outlet of the condenser; A valve to shut off the incoming nitrogen, a valve for shutting off the liquid product leaving the condenser before the gas-tight connection with the receiving vessel; a valve for blocking the gaseous product leaving the condenser before the gas-tight connection with the expansion flask; a device for feeding the substantially plastic material in an at least partially molten state to a pyrolysis reactor as previously described, two gravimetric dosing devices for dosing the granulated polymer mixture in the hopper of said twin-screw extruder for dosing the granulated polymer mixture in a reactor; Equipped with.

[0266] The probe used in these examples for detecting transmission spectra is a Hellma Excalibur HD FPT25 immersion probe made from Hastelloy C-22 with a sapphire window.

[0267] The probe has a diameter of 25 mm, an optical path of 5 mm and maximum operating conditions of 290°C and 27 bar.

[0268] The probe is inserted into a well located in the reactor vapor outlet pipeline immediately downstream of said pressure regulating valve. The location of the probe in the well is recessed so that the window is always filled with condensed hydrocarbon liquid. Condensation is obtained by removing the insulation of the pipe section preceding the probe.

[0269] A reduced diameter pipe connected to said well corresponding to the probe allows the well to be emptied at the end of an experiment and between one test to ensure withdrawal of the hydrocarbon liquids read by the probe and complete exchange of the condensate. This sampling is used to take samples during the calibration phase of the probe, but not during the production phase.

[0270] The probe was connected to a Fourier transform spectrometer (FT-NIR) Bruker Matrix-F model using a 600 μm diameter optical fiber for both emission and detection. The spectrometer was equipped with an InGaAs detector and had a spectral range of 12800–4000 cm. -1 , with a spectral resolution of 2 cm -1 It is also equipped with an industrial PC connected via Ethernet and a Modbus interface for communication with the control system (DCS, PLC) of the pyrolysis plant. In production mode, the spectrometer continuously measures the spectrum "Ax", from which the value of "Px" is determined by the pre-calculated calibration curve "Cx".

[0271] The direct feedback control is set by two controllers with PID algorithms (proportional, integral, derivative) or one each for the variables "Px", refractive index "RI" and viscosity "VI". The process parameter "Ox" selected for feedback is the pressure. The device on which the controller acts is a pressure regulating valve. In "man" mode the controller acts directly on the position of the valve actuator (operating point "OP" = 0 - valve closed, "OP" = 100 - valve 100% open). On the other hand, in "auto" one has to set the value of the desired parameter "Px" and the regulator acts on the actuator position (changing the operating point "OP") so that the measured value of "Px" reaches the set value.

[0272] To select which variable to perform the feedback on, a selector at the output of the PID controller relates to the refractive index "RI" or viscosity "VI" being sent.

[0273] The latency between the acquisition of the spectrum "Ax" and its action on the stem (i.e. on the pressure step parameter "Ox"), which includes the spectrum acquisition time, the evaluation of "Px" and the use of this value for the calculation of the next position of the actuator, is less than one minute. In this regard, it should be noted that the latency is independent of the integral and derivative times of the PID controller. In fact, these act on the regulation speed, whereas the latency is a measure of the action delay and does not act on the instantaneous value of the characteristic "Px", but always on a delayed value.

[0274] Calibration Example Determination of calibration curve "Cx" "Device 1" was used to prepare the pyrolysis oil samples used as sample materials. For this purpose, we tried to make the sample materials as diverse as possible in order to obtain a stable calibration curve "Cx" (and therefore to accommodate heterogeneous materials). Four recycled materials B01, B02, B03 and B04 and two materials obtained from a mixture of virgin materials PATA and PATB were selected as mixtures. Pyrolysis was carried out at 430 °C with varying pressures and residence times, and the sample materials were taken for primary analysis immediately after measuring their spectra with the probe.

[0275] The calibration curves were determined according to the "rotation" mode described above, selecting five sample materials for validation and the remaining sample materials as calibration samples for multivariate regression. A second round was performed by selecting five other sample materials (different from the first sample material) for validation and the remaining ones as calibration samples for multivariate regression. This was done in the same way until all sample materials had been used as test samples at least once. This procedure was performed both for the determination of the calibration curve "Cx" for viscosity "VI" and for the determination of the calibration curve "Cx" for refractive index "RI".

[0276] For determining "Cx" for refractive index ("RI"), 27 sample materials were used in 6 rounds, with only 2 sample materials used in the final round (total validation samples: 5+5+5+5+2=27). For determining "Cx" for viscosity ("VI"), 23 sample materials were used in 5 rounds, with only 3 sample materials used in the final round (total validation samples: 5+5+5+5+3=23).

[0277] Partial least squares (PLS) multivariate regression was applied.

[0278] The final calibration curve uses loading values ​​given by the average of the loadings identified according to the rotation method described above.

[0279] Select the number of components The number of PLS ​​components used in the model was evaluated.

[0280] A small number of components reduces the accuracy of the model, while a large number of components runs the risk of overfitting, reducing the model's extrapolation and interpolation capabilities. Therefore, it is generally best to choose the number of components that minimizes the error, and if there are multiple horizontal axis values ​​that maintain the minimum error, it is advantageous to choose the smallest horizontal axis value.

[0281] Figure 3 shows the results and shows that for the viscosity calibration curve "Cx", the mean squared error in the prediction is already reduced to low values ​​by using the first 5 components (NC=5). For the refractive index, the optimum value turns out to be 8 components. As can be seen from Figure 3, both choices correspond to the value of the number of components that minimizes the mean squared error. In this case, for a number of components larger than the selected value, the quadratic error increases. However, if the trend remains flat (i.e. a minimum value is reached and then maintained for larger values ​​of the horizontal axis), it is advisable to choose the smallest number of components that minimizes the mean squared error.

[0282] Prediction accuracy of calibration curve "Cx" Figures 1 and 2 respectively show the refractive index "RI" and viscosity "VI" calculated using the calibration curves compared to the corresponding "measured" values ​​(i.e., values ​​determined based on primary analysis using the methodology and equipment described above), demonstrating the high predictive power and accuracy of the method disclosed in this invention.

[0283] Production Examples (Comparative Examples and Examples) Example 1 In the reactor of the aforementioned "Device 1", already preheated for 6 hours at 430° C. and inerted with a nitrogen flow, the "PATA" mixture was continuously fed by the gravimetric dosing device and the extruder. Initially, the selector of the pressure regulating valve was set based on the output of the refractive index regulator, while the latter regulator was set to "Man" and the operating point "OP" was set to 100 in order to keep the valve opening at 100%, thus maintaining the pressure of the reactor at a substantially atmospheric level (about 1.1 bar).

[0284] The flow rate of the gravimetric dosing device was adjusted so that there was an initial filling of about 1 / 3 of the reactor height (determined by the level of the "DP-cell") and was then reduced to keep said level substantially constant. In this way, the residence time, calculated as the ratio of the reactor filling volume to the volumetric flow rate of the substantially molten polymer (calculated as the ratio of the mass flow rate of the gravimetric dosing device to the density of the substantially molten plastic material), was found to be about 6 hours.

[0285] The pyrolysis vapors generated in the reactor were condensed by the condensation system, whereas the non-condensable vapors were collected from the expandable flask. The shutoff valve allowed the expansion flask and the condensate collection volume to be changed during the test. The viscosity "VI" and the refractive index "RI" were continuously monitored by measuring the spectrum "Ax" of the pyrolysis oil, i.e., the hydrocarbon liquid passing in front of the spectrometer.

[0286] This continued for 12 hours. The viscosity value "VI" thus obtained stabilized at about 1.10 cP, and the refractive index "RI" stabilized at about 1,445 nD.

[0287] The pyrolysis reaction and all other process parameters were stable, i.e., there were no fluctuations and no time shifts. Liquid and gas samples taken under these conditions were subjected to analysis.

[0288] Example 2 Example 1 was not repeated, but continued as follows: the pressure controller was set to "AUTO", thus activating the feedback on the refractive index "RI". The target refractive index ("set point") was set to 1.44 for about 2 hours, then 1.435 for another 2 hours, 1.43 for another 2 hours, and finally 1.425 for another 2 hours. The control also stabilized at all conditions, gradually leading to partial closure of the pressure regulating valve. At the final condition (RI=1.425), the pressure in the reactor stabilized at about 5.5 bara. The viscosity VI was also continuously evaluated in the same way, settling at about 0.89 cP.

[0289] Under all conditions, the refractive index values ​​obtained were stable and consistent with the values ​​set on the controller. Samples taken under these conditions were used for analysis.

[0290] Example 3 Example 2 was repeated, except that it continued by verifying the stability of the feedback control on viscosity. For this purpose, first the relevant regulator was set to "man" and OP was set to the value set by the refractive index PID regulator. Then the signal selector was moved to the pressure control valve of the viscosity PID output. The target viscosity ("set point") was set to 0.89 and the controller was set to "auto". The control stabilized. The set viscosity was then increased to 0.95 and held for 2 hours, then increased to 1.04 and held for another 2 hours, and finally increased to 1.1 cP and held for another 2 hours. The pressure control valve was gradually opened.

[0291] Under all conditions, the viscosity values ​​obtained stabilized and converged to the value set by the controller. The reactor pressure gradually decreased, returning to essentially atmospheric pressure.

[0292] Reactor regeneration: The mixture feed was stopped and the remaining material in the reactor was pyrolyzed until exhausted, after which it was cooled and held under nitrogen for an additional 6 hours.

[0293] The reactor was then opened and found to have signs of fouling.

[0294] Example 4 Example 1 was repeated, except that the "PATB" mixture was fed continuously instead of "PATA".

[0295] The "VI" viscosity value was about 1.65 cP, and the "RI" refractive index was about 1.505 nD.

[0296] Samples taken under these conditions were submitted for analysis.

[0297] Example 5 Example 4 was repeated, except proceeding as follows: The pressure controller was set to "AUTO" with feedback to the refractive index "RI". The target refractive index ("set point") was set to 1.505 for about 2 hours, then lowered to 1.49 for an additional 2 hours, recording a viscosity equal to about 1.58 cP, and then lowered to 1.48 for an additional 2 hours, recording a viscosity equal to about 1.52 cP. This adjustment was fairly stable, but less precise than Example 2.

[0298] It was therefore decided to take samples for analysis and to discontinue the test, whilst still carrying out the regeneration as in Example 3. After regeneration, the inside of the reactor was found to show extensive fouling. Cleaning by brushing and blowing was carried out.

[0299] Example 6 Example 4 was repeated again, again using the "PATB" mixture, except that this time the selector was again set on the refractive index controller and the controller was immediately set to "AUTO" mode while simultaneously setting the target refractive index ("set point") to 1.44.

[0300] The pressure gradually increased to about 6.5 bara and stabilized around this value. This value was maintained for about 12 hours, while good stability of all parameters was confirmed. The refractive index stabilized around about 1.44 nD and the viscosity gradually decreased to about 0.95 cP. The feedback control on the viscosity regulator was then tested again and the set point was set to 0.95 cP. The regulator was stable. Samples taken under these conditions were submitted for analysis.

[0301] Example 7 Continuing with Example 6, the feedback on viscosity was set to 0.88 cP. The pressure increased and stabilized at about 7.5 bara. The refractive index was again measured by correlation "Cx" to be about 1.43 D. The regulator was stable. A sample taken under these conditions was submitted for analysis.

[0302] Samples taken under these conditions were submitted for analysis, after which the reactor was regenerated as indicated in Example 3. The reactor was then opened and no fouling was observed to be present.

[0303] Example 8 Example 1 was repeated, except that instead of the "PATA" mixture, a "B02" mixture of recycled material was continuously fed.

[0304] The refractive index controller was immediately set to "AUTO" mode with the selector set to the refractive index controller and the target refractive index ("set point") set to 1.44. The pressure gradually increased to about 5.5 bara and stabilized around this value. The system was conditioned for about 12 hours with no issues observed. The reactor was then cleaned as in Example 3. The reactor was then opened and no fouling was observed to be present in it.

[0305] analysis The collected samples were treated as follows: The obtained pyrolysis oil (liquid contained in the receiving liquid) was weighed and then subjected to ultracentrifugation (Sorvall Evolution RC ultracentrifuge manufactured by Thermo Scientific) at 25,000 rpm for 45 minutes.

[0306] After ultracentrifugation, the fraction remaining at the bottom (hereinafter referred to as the wax fraction) and the supernatant (hereinafter referred to as the oil fraction) were separated and weighed.

[0307] The oil concentration (%) was calculated by dividing the weight of the resulting oil fraction by the weight of the material initially fed to the reactor.

[0308] The wax concentration (%) was calculated by dividing the weight of the resulting wax fraction by the weight of the material initially fed to the reactor.

[0309] The mass of gas produced was calculated as the difference between the weight of the material initially fed to the reactor and the sum of the weights of the wax and oil fractions. The gas fraction produced was calculated by dividing the mass of the gas fraction thus calculated by the weight of the material initially fed to the reactor.

[0310] The resulting fractions were analyzed using the techniques described above. Approximately 130 compounds were identified.

[0311] For each of these compounds, the atomic mass fractions were calculated from the number of atoms of each element and the atomic mass of each atom.

[0312] The term "C5-C12 yield" refers to the sum of the masses of compounds with 5 to 12 carbon atoms (including the maximum) in the evaporated pyrolysis product relative to the total mass fed. Similarly, "C21+ yield" refers to the sum of the masses of compounds with at least 21 carbon atoms in the evaporated pyrolysis product relative to the total mass fed.

[0313] The term "C5-C12 fraction" refers to the sum of the masses of compounds in the product having 5 to 12 carbon atoms (including the maximum) relative to its total mass. Similarly, the term "C21+ fraction" refers to the sum of the masses of compounds in the product having at least 21 carbon atoms relative to its total mass.

[0314] Thus, the term "evaporative pyrolysis products" refers to the sum of the gas, oil, and wax fractions, but does not include the residual solids (char).

[0315] For this purpose, gas chromatographic analyses are carried out separately for each of the gas, oil and wax fractions and the yield of a given compound "C" is then calculated according to the following formula: TIFF2025501984000009.tif10103[In the formula, X C, <frac>< / frac> is the identified product fraction <frac>is the mass fraction of compound C in ( <frac>(where GAS = gas fraction, oil fraction, or WAX = wax fraction). In the case of the GAS fraction, this fraction has already been excluded from the calculation of the nitrogen present (it is supplied as an inert gas and is not a pyrolysis product). The chromatogram of the GAS fraction is a conversion of parts by volume to parts by weight, assuming that parts by volume correspond to parts by mole, and then calculating parts by weight once the molecular weight of the compound is known. f OIL and f WAX are the mass fractions of the oil and wax fractions, respectively, and are calculated by dividing the weight of the recovered material by the weight of the material fed to the pyrolysis. The mass of the non-condensable vapors was estimated based on the volume of the inflatable balloon and the density of the gas calculated based on the compositional analysis of the gas present therein. The mass of the solid residue in the reactor was then calculated by multiplying the mass of the essentially plastic material fed and the mass of the recovered pyrolysis oil (including wax) by the following formula: TIFF2025501984000010.tif1391] It was calculated by:

[0316] result The following table shows the C5-C12 yield, C21+ yield (21 or more carbon atoms), the content of some compounds, and the fouling in the reactor: TIFF2025501984000011.tif89157

[0317] The amount of hydrocarbons in the obtained pyrolysis oil was always higher than 90% by weight. Examples 2, 6 and 7 of the present invention showed a C5-C12 yield at least equal to 30% and at the same time a C21+ yield at most equal to 3%.

[0318] Discussion of results One of the objectives of the present invention is to solve the important problems of pyrolysis of substantially plastic materials with widely different compositions and to maintain the high quality of the pyrolysis products. Therefore, both mixtures of virgin materials with different compositions and recycled materials were evaluated.

[0319] The experiments carried out have shown that it is possible to carry out a stable feedback control on the evaluated parameters of the pyrolysis oil obtained at low latency, in particular by evaluating their transmission spectra and carrying out an evaluation of their properties "Px", such as the refractive index "RI" and / or the viscosity "VI".

[0320] Furthermore, the present invention shows that by setting the feedback control set point within a certain range, the reactor can be kept clean. Indeed, Examples 1, 2, 6, 7 and 8 show that both the viscosity and the refractive index are within the range, and the pyrolysis reactor remains clean even after many hours of operation. In contrast, Comparative Examples 6 and 7 show that if set outside the range, fouling problems may occur. Fouling is undesirable because it can interfere with the control over time and can be drawn into the generated pyrolysis oil, accumulating over time and forcing cleaning breaks.

[0321] Finally, the pyrolysis oils obtained in Examples 2, 6 and 7 (each with a C21+ fraction less than 3.5% and a C5-C12 fraction equal to at least 35%) were fed to a steam cracking pilot reactor, with good yields of monomers useful for the formation of new polymers and no operational problems or fouling.

[0322] A mixture of virgin polymers was used to take advantage of the stability and knowledge of the substantially plastic material fed to the reactor, and to substantially eliminate doubts regarding the heterogeneity of the plastic material, but tests with recycled materials were also satisfactory. [Explanation of symbols]

[0323] 51 ... Auxiliary gas fluid 52 ... Pyrolysis steam 53 … solid residue 54 … Substantially plastic material 56, 59 ... Residual gas 57, 58 ... Steam 60 … Condensate 61 ... Secondary condensate 62 ... Third condensate 70 ... Pyrolysis reactor 71 ... Second reactor 72 … First pressure control device (regulating valve) 73 ... First condenser 74 … Second condenser 75 ... Third condenser, immersed condenser, condensate separator 76, 77, 78 … Regulating valve 80 ... Pressure value, pressure signal 83 … Level signal 85 … Signal 86 … Set point indication 87 … Opening instruction 90 … Pipe section 91 ... Pipe 92 … Angular profile 93 ... Luminescent probe 94 … Receiving probe 95 … Temperature detection probe< / frac> < / frac>

Claims

1. (a) feeding a substantially plastic material into a pyrolysis reactor; (b) subjecting the material in the pyrolysis reactor to a temperature of between 330°C and 580°C in the substantial absence of oxygen, at a pressure between atmospheric and 13 bara; (c) maintaining the material in the pyrolysis reactor for a time sufficient to produce a gaseous effluent; (d) partially or completely condensing said effluent in gaseous state to form at least one fluid that is liquid at 25°C and that contains at least 10% by weight of hydrocarbons, quantitatively relative to the weight of the substantially plastic material fed; (e) performing an evaluation of at least one property "Px" of the liquid condensed from said effluent in gaseous state by measuring at least one spectrum "Ax" of transmission, reflection or transflectance of said condensed liquid; (f) adjusting at least one process parameter "Ox" according to said evaluation of at least one property "Px"; (g) iteratively repeating steps (e) and (f) so as to maintain said at least one property "Px" substantially constant over time; Including, 10. A method for the pyrolysis of substantially plastic material to obtain hydrocarbons that are liquid at least at 25°C, wherein the measurement of "Ax" is carried out directly on the condensed liquid by a spectrometer or spectrophotometer.

2. 2. A method for the pyrolysis of substantially plastic materials according to claim 1, wherein said at least one property "Px" of the liquid condensed by said effluent in gaseous state is refractive index and / or viscosity.

3. 3. A method for substantially pyrolyzing plastic materials according to claim 2, wherein said at least one property "Px" of the liquid condensed by said effluent in gaseous state is a refractive index.

4. 3. A method for pyrolyzing substantially plastic materials according to claim 2, wherein said at least one property "Px" of the liquid condensed by said effluent in gaseous state is viscosity.

5. 4. A method for substantially pyrolyzing plastic material according to claim 3, wherein said adjustment of at least one process parameter "Ox" is performed by setting the set point of the refractive index characteristic "Px" to a value between 1.415 and 1.465 nD, preferably between 1.42 and 1.455, more preferably between 1.425 and 1.

45.

6. 5. A method for substantially pyrolyzing plastic materials according to claim 4, wherein said adjustment of at least one process parameter "Ox" is performed by setting the set point of the viscosity characteristic "Px" to a value between 0.7 and 1.2 cP, preferably between 0.8 and 1.1 cP, more preferably between 0.85 and 1.05 cP.

7. 7. A method for pyrolyzing a substantially plastic material according to any one of claims 1 to 6, wherein the parameter "Ox" is at least one of the pyrolysis pressure, the pyrolysis temperature, the residence time of the substantially plastic material in the pyrolysis reactor, the flow rate of the substantially plastic material in the pyrolysis reactor, and the ratio of the flow rates between the plurality of substantially plastic materials fed to the pyrolysis reactor.

8. 2. A method for substantially pyrolyzing plastic materials according to claim 1, wherein the waiting time between the measurement of the spectrum "Ax" and its use in adjusting the process parameter "Ox" can be set to a value not exceeding 1 hour, preferably not exceeding 10 minutes, more preferably between 1 and 60 seconds.

9. 2. The method for substantially pyrolyzing plastic materials according to claim 1, wherein step (d) of partially or totally condensing the effluent in a gaseous state is obtained by partially condensing the effluent in a gaseous state of the pyrolysis reactor by cooling at least a portion of the effluent in a gaseous state.

10. 2. The method for substantially pyrolyzing plastic materials according to claim 1, wherein the gaseous effluent in step (d) is pyrolysis steam contained directly in the pyrolysis reactor or pyrolysis steam contained in an outlet duct for pyrolysis steam from the pyrolysis reactor.

11. 11. A method for the pyrolysis of substantially plastic materials according to claim 10, wherein, when the effluent in gaseous state in step (d) is pyrolysis vapor contained in an outlet duct for pyrolysis vapors from the pyrolysis reactor, the vapors are conveyed to an area where condensation at least partially occurs, and the measurement "Ax" is carried out within 2 minutes, preferably between 1 and 60 seconds, after the vapors have entered the outlet duct from the reactor.

12. Step (d) is withdrawing the pyrolysis vapor stream from the pyrolysis reactor through a pyrolysis vapor outlet duct; directing the withdrawn vapor stream to a condenser to condense at least 50% of the vapor; carrying out a measurement "Ax" on the condensed liquid, preferably in the lower part of the condenser, which serves as a liquid storage volume; directing the non-condensable vapors to the pyrolysis reactor, to a pyrolysis vapor outlet duct, or to the remaining pyrolysis vapors prior to condensation in step (d) of the process; Sending the liquid to the pyrolysis reactor or to said pyrolysis vapor outlet duct, preferably by gravity, and returning the liquid to the main flow.

2. The method of claim 1 for pyrolyzing a substantially plastic material, comprising:

13. 2. A method for pyrolyzing a substantially plastic material according to claim 1, comprising obtaining at least one calibration curve "Cx" capable of correlating the transmission, semi-transmission or reflection spectrum of the hydrocarbon liquid obtained by pyrolysis with the value of at least one property "Px" of said hydrocarbon liquid, said calibration curve "Cx" being obtained by applying a multivariate regression method, preferably multiple linear regression (MLR), principal component analysis (PCR) regression or partial least squares (PLS) regression.

14. 2. A method for substantially pyrolyzing plastic material according to claim 1, wherein the optical path of the light is less than 25 mm, or between 3 and 18 mm, or between 5 and 15 mm, or between 7 and 11 mm, when the measurement "Ax" is carried out in transmission or semi-transmission mode.

15. The measurement "Ax" is at least 4000 to 12000 cm －１ , or 4500 to 10000 cm －１ , or 5000 to 9000 cm －１ 10. The method of claim 1, wherein the method is carried out using a probe capable of emitting light having a wave number of 1000 to 10 ...

16. 10. The mixture obtainable from the process according to claim 1, comprising at least 90% by weight of hydrocarbons, having a refractive index measured in accordance with the method defined below of 1.415 to 1.465 nD, preferably 1.42 to 1.455, more preferably 1.425 to 1.45, and a viscosity measured in accordance with the method defined below of 0.7 to 1.2 cP, preferably 0.8 to 1.1 cP, more preferably 0.85 to 1.05 cP, and a tetrahydrofuran (THF) content of not more than 1% by weight, preferably 0.01 to 0.25% by weight, more preferably 0.07 to 0.19% by weight, based on the total weight of the mixture.

17. 17. A mixture comprising at least 90% by weight of hydrocarbons according to claim 16, further comprising a C5 to C12 content at least equal to 35% by weight, a C21 and higher content at most equal to 3.5% by weight, not more than 0.55% by weight, preferably between 0.15% and 0.3% by weight, of isobutene, and / or not more than 2% by weight, preferably between 0.01% and 1% by weight, of benzoic acid, all percentages relative to the total weight of the mixture.

18. 18. Use of a mixture according to claim 16 or 17 in feeding a steam cracking plant to obtain monomers useful for the production of polymers.

19. at least one reactor for substantially pyrolyzing plastic material; at least one condensation separator that receives and at least partially condenses vapor from the at least one reactor; at least one device for measuring "Ax" the spectrum of transmission, reflection or transflectance of a liquid condensed from said effluent in gaseous state, said "Ax" measurement being performed directly on said condensed liquid using a spectrometer or spectrophotometer; at least one system for evaluating at least one property "Px" of the liquid condensed from said effluent in gaseous state by means of at least said measurement "Ax"; at least one regulation system for a process parameter "Ox" as a function of said measurement value "Ax" of said at least one characteristic "Px"; 1. An apparatus for the pyrolysis of substantially plastic materials to obtain hydrocarbons that are liquid at least at 25°C, comprising:

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