Reactor for the thermal treatment of raw feedstocks of renewable origin intended for the production of biofuels

Abstract

A reactor (100) for the thermal treatment of purification of a fluid (F) comprising at least one raw feedstock of renewable origin, intended for the production of biofuels, and possibly water or an acid / basic aqueous solution, is described, wherein said reactor (100) comprises a plurality of serpentine modules (1; 1'; 1"; 1'"; ln) arranged within a chamber filled with an inert gas and contained within an insulated casing, said reactor (100) being devoid of heating means for providing heat to said fluid (F) passing through said reactor (100); wherein the insulating layer (30) has a thickness such that the difference between the inlet temperature (Tin) of said fluid (F) and the outlet temperature (Tout) of said effluent (E) is less than or equal to a predefined value for said thermal treatment in said reactor (100).

Description

[0001] REACTOR FOR THE THERMAL TREATMENT OF RAW FEEDSTOCKS OF RENEWABLE ORIGIN INTENDED FOR THE PRODUCTION OF BIOFUELS DESCRIPTION

[0002] The present invention relates to a reactor for the thermal treatment of purification of raw feedstocks, generally of renewable origin such as those intended for the production of biofuels, wherein said reactor comprises at least one tubular element with a serpentine structure which is inserted in an inertized chamber of a casing that is insulated in such a way as to act as a thermal insulation structure for said tubular element so as to avoid supplying heat to the fluid passing through the reactor by means of heating means, or heat exchange means, arranged within the reactor.

[0003] It is known in the art that many processes for transforming renewable feedstocks into biofuels, such as upgrading and / or Ecofining™ processes, are based on catalytic processes that require the feedstock to be substantially devoid of metal pollutants and phosphorous (present in many renewable feedstocks in the form of phospholipids) in order to preserve catalyst activity.

[0004] Different industrial pre- treatment processes are currently being used, depending on the type of renewable raw feedstock, on its metal pollutant and phosphorous content, and on the type of transformation into biofuels.

[0005] Some of these processes provide for the use in series of various methodologies, each specific for the removal of specific impurities, while a smaller number of processes provide for the removal of all impurities in a single step by operating in a single thermal treatment reactor wherein the fluid is heated to the thermal treatment temperature and maintained at that temperature inside the reactor by means of heating means placed within the reactor, e. g. by means of heat exchange fluids put in contact with the tube through which the material to be treated passes.

[0006] The use of a heat exchange fluid inside the reactor makes it necessary to provide a circulation unit for this fluid, which in turn must be heated by means, for example, of a combustor, with an obvious increase in the reactor construction costs and in a greater complexity in managing it.

[0007] It is therefore desirable to have available a reactor for the thermal treatment of raw renewable feedstocks for purification from metallic pollutants and phosphorous, which is simplified, cheaper and easier to handle.

[0008] It is also desirable to have available a reactor such as the one defined above that is also modular and which can be modulated in terms of reaction volume so that it can be constructed more easily and quickly than non-modular reactors.

[0009] It is an obj ect of the present invention a reactor of thermal purification treatment, by means of a non-catalytic reaction, of a fluid F comprising at least a raw feedstock of renewable origin, which is intended for the production of biofuels, and comprising optional water or an acid / basic aqueous solution, wherein said reactor comprises:

[0010] - one or more continuous tubular elements, each arranged in a respective horizontal plane and each having a serpentine development in said respective horizontal plane so as to form a respective continuous serpentine module, said continuous tubular elements being in fluid communication with each other and defining a reaction volume V of said reactor;

[0011] an inlet of said fluid F having a predetermined temperature Tinof entrance into said reactor;

[0012] - an outlet of an effluent E comprising said feedstock of renewable origin in purified form, said effluent E having an outlet temperature

[0013]

[0014] T

[0015] wherein

[0016] said continuous tubular elements having a serpentine development and lying in respective horizontal planes are all contained inside a sole casing which is covered by a layer of thermal insulation material insulating from the outside;

[0017] or

[0018] each of said continuous tubular elements having a serpentine development and lying in respective horizontal plane is contained inside a respective casing covered by a layer of thermal insulation material insulating from the outside;

[0019] said layer of thermal insulation material of said casing having a thickness such that, in use, the value of the difference between the inlet temperature Tinof the fluid F and the temperature Toutof the effluent E at the outlet from the reactor is less than or equal to a value predetermined for said heat treatment in said reactor.

[0020] It is a particular obj ect of the present invention a reactor 100 for the thermal treatment of purification, by means of a non-catalytic reaction, of a fluid F comprising at least a raw feedstock of renewable origin which is intended for the production of biofuels, and possibly water or an acid / basic aqueous solution, wherein said reactor 100 comprises

[0021] - one or more continuous tubular elements 1; 1 '; 1"; 1 ' ";

[0022] lneach arranged in a respective horizontal plane and in fluid communication with each other, each of said continuous tubular elements 1; 1 '; 1"; 1 ' "; lnhaving a serpentine development in said respective horizontal plane and a bare surface, said one or more tubular elements 1; 1 '; 1"; 1 ' "; lndefining a reaction volume V of said reactor 100;

[0023] - an inlet 4 of said fluid F having a predetermined inlet temperature Tinin said reactor 100;

[0024] - an outlet 6x of an effluent E comprising said feedstock of renewable origin in purified form, said effluent E having an outlet temperature Tout;

[0025] - a casing 20 which defines an internal chamber 40 wherein the one or more tubular elements 1; 1 '; 1"; 1 ' "; lnare arranged with a serpentine development, said internal chamber 40 being further filled with an inert gas having a temperature varying from Tinto Tout, said casing 20 being covered by a layer 30 of thermal insulation material with respect to the outside;

[0026] said reactor 100 being devoid of heating means to supply heat to said fluid F passing through said reactor 100; and said layer 30 of thermal insulation material having a thickness such that, in use, the value of the difference between the inlet temperature Tinof the fluid F and the outlet temperature Tout of the effluent E is less than or equal to a predetermined value for said heat treatment in said reactor 100.

[0027] The aforesaid prefixed temperature difference value is identified in use ( steady-state conditions ) and is a value that takes into account the fact that, if compared to the selected thermal treatment temperature, e. g. 250 °C, this thermal treatment may have a lower limit of temperature below which the fluid does not undergo sufficient thermal purification, e. g. 220 °C, and that the fluid may have an upper limit of temperature, e. g. 280 °C, above which secondary reactions competing with the heat treatment may occur, including possible flammability problems of the fluid.

[0028] The term "raw feedstocks", "raw feedstock" herein means to identify one or more raw materials, generally of renewable origin, which are in liquid or semi-solid form and which contain impurities such as, for example, metal compounds and phospholipid compounds that can be eliminated through thermal treatment at high temperatures, generally higher than 150 °C.

[0029] Said one or more raw feedstocks may possibly, or preferably, be added with water or acid / basic aqueous solutions, before being fed to the reactor 100 of the invention in the form of fluid F.

[0030] The term "reactor" herein means to identify an apparatus provided with at least one reaction volume V wherein a fluid F undergoes a thermal treatment reaction of purification as it passes through said reactor.

[0031] The term " thermal treatment of purification" herein means to identify a thermal process wherein a non-catalytic reaction takes place, whereby raw feedstocks, generally of renewable origin, containing impurities such as, for example, phospholipids and metal compounds are purified from said impurities at a temperature that may be in the range of 150 °C to 280 °C or 200 °C to 300 °C, possibly in the presence of water or acid / basic aqueous solutions.

[0032] An example of heat treatment of raw feedstocks of renewable origin wherein the reactor 100 of the present invention may be advantageously employed is the one disclosed in patent application WO2022214993A1, on behalf of the Applicant, which is incorporated herein in its entirety by reference. In this patent application, the disclosed process provides that the non-catalytic heat treatment is applied to raw, edible or non-edible bio-feedstocks, such as vegetable oils, animal fats, derivatives thereof, including used cooking oil and by-products / scraps obtained from the processing thereof and the like, intended for processes of transformation into biofuels.

[0033] In particular, the process disclosed in WO2022214993A1 can advantageously be applied to tobacco oil and palm oil, used cooking oil (UCO), crude soybean oil, CAT 1, 2 and 3 animal fats, acid oils, husk oil, crude palm oil mill effluent and any by-products thereof.

[0034] With the aforesaid thermal process of the prior art, an efficient reduction of the content of metal contaminants such as heavy and / or transition metals, phosphorus, alkali metals and alkaline earth metals can be achieved, obtaining a purified bio-feedstock with a total content of these metal contaminants of less than 10 ppm total and / or a total phosphorus content of less than 3 ppm, which can be achieved in the prior art by a degumming process followed by a bleaching process.

[0035] This non-catalytic thermal process disclosed in WO2022214993A1 involves the steps of

[0036] - Placing said one or more raw bio-feedstocks in contact with water or acidulated water to form a fluid in the liquid phase, preferably a fluid in the form of an aqueous emulsion;

[0037] - Subj ecting said fluid in the liquid phase to a thermal treatment in a reactor, at a temperature of 200-300 °C, preferably 230 °C-260 °C, for a residence time up to 30 minutes, preferably between 1 minute and 5 minutes operating at a pressure greater than 10 barg up to 65 barg, preferably between 45 and 55 barg, obtaining an effluent at the outlet of said reactor comprising said purified bio-feedstock; - subjecting said effluent to at least one non-adsorptive physical separation to separate said metallic contaminants including phosphorous from said effluent containing the purified bio-feedstocks.

[0038] The term "bare tube", "bare tubes", "bare tubular elements" herein means to identify a tube, the tubes, the tubular elements that

[0039] - do not have an insulated surface, i. e. they are not covered with insulation layers;

[0040] - do not have the surface heated by heating means, i. e.

[0041] are not affected by heat transfer fluids, are not wrapped by electrical resistances that heat the surface of the tube, tubes, tubular elements and / or the fluid flowing through them.

[0042] Said bare tubes or tubular elements may optionally have fins on their surface, i. e. the surface of the tube, tubes, tubular elements may optionally be finned.

[0043] The invention will now be described in detail with reference to a non-limiting embodiment of the reactor 100 of the invention shown in the attached figures, wherein Figure 1 is a perspective view of the reactor 100 of the present invention, wherein the cover panels have been removed so as to allow a view of the inside of the reactor 100, including the chamber 40 inside the casing 20;

[0044] Figure 2 is a perspective view of a plurality of tubular serpentine elements 1, 1 ', 1", 1 ' ", lndefining a reaction volume V, which are contained in the internal chamber 40 of the casing 20 of the reactor 100;

[0045] Figure 3 is an enlarged view of the detail enclosed in the dashed box A of Figure 2.

[0046] As mentioned above, the reactor 100 of the invention can advantageously be fed with a fluid F comprising a raw feedstock, as defined above, mixed with water or an acid solution.

[0047] In said reactor 100, a non-catalytic reaction takes place producing an effluent E at the outlet, which comprises the purified feedstock as it is substantially devoid of the phospholipids and metal compounds initially present in the raw feedstock. Said effluent E further comprises an aqueous phase, the impurities removed from the raw feedstock in the form of a solid phase, and a gas / steam phase.

[0048] The reactor 100 of the invention includes, as said, a casing 20, generally in the shape of a parallelepiped, although this shape is not binding for the purposes of the present invention.

[0049] Said casing 20 may be a typical container having dimensions and structure in accordance with ISO standardization, for example an ISO ( International Organization for Standardization) container, or it may be a cage structure in the form of a parallelepiped structure, which is composed of a plurality of horizontal and vertical beams 200 (fig.1) connected and constrained to each other, without departing from the scope of protection and obj ect of the present invention.

[0050] A layer 30 of a thermally insulating material, which is also herein referred to as "insulation" for the sake of simplicity, is present (fig. 1) arranged all around said casing 20.

[0051] In particular, said layer 30 of a thermally insulating material is mainly arranged in all the hollow areas of the cage structure generated by the aforesaid horizontal and vertical beams 200.

[0052] This casing 20 may also provide a series of external panels ( not shown in the figure ) to cover and protect said insulation layer 30 arranged around thi s casing 20.

[0053] The reactor 100 of the invention further advantageously compri ses a plural ity o f continuous bare tubular elements 1, 1 ', 1", 1 ' ", ln(with n= integer number corresponding to the total number of the tubular elements provided to form a given reaction volume ) as de fined above, also herein re ferred to as " continuous tubul ar serpentine modul es".

[0054] As shown in Figure 2, each continuous tubular serpentine module 1, 1 ', 1", 1 ' ", lni s arranged on a respective hori zontal plane and said serpentine modules 1, 1 ', 1", 1 ' ”, lnare arranged as superimposed and spaced apart along the vertical.

[0055] Each continuous serpentine module 1, 1 ', 1", 1 ' ", lncons ists of a plural ity o f straight tubes 2 and a plurality o f curves 3 having a 180 ° curvature, wherein the straight tubes 2 alternate with the curves 3 so as to form a continuous serpentine conf iguration.

[0056] These straight tubes 2 and these curves 3 o f each serpentine module 1, 1 ', 1", 1 ' ", lnare elements having a bare surface, as de fined above, and are in f luid communication with each other.

[0057] The straight tubes 2 and the curves 3 of each serpentine module 1, 1 ', 1", 1 ' ", lnare also connected to each other by means o f fastening systems known to the person s kil led in the art, for example by welding, threading, f langes, malefemale coupl ing or the l ike, without thereby depart ing from the scope of the present invention.

[0058] In one embodiment, the straight tubes 2 and curves 3 of each serpentine module 1, 1 ', 1", 1 ' ", lnare connected to each other by welding.

[0059] Each o f said serpentine modules 1, 1 ', 1", 1 ' ", lnrests on hori zontal supporting beams (not shown in the figure ) which are f ixed to the cas ing 20.

[0060] The cas ing 20 therefore acts both as a structure supporting the serpentine modules 1, 1 ', 1", 1 ' ", lnand as a thermal containment structure with respect to the outs ide.

[0061] In addition, the casing 20 al so acts as a safety structure to contain the fluid F entering the reactor 100 in the event o f leakage from the connections between the tubes 2 and curves 3 o f the serpentine modules 1, 1 ', 1", 1 ' ", ln.

[0062] In particular, a col lection tank ( not shown in the figure ) arranged at the bottom o f the reactor 100 may al so be provided within the cas ing 20 to contain any f luid leakage at the connections between the tubes 2 and the curves 3 of the modules 1, 1 ', 1", 1 ' ", ln, e. g. from the connection welds.

[0063] Said serpentine modules 1, 1 ', 1", 1 ' ", lnare in f luid communication with each other as they are connected in series with each other: the mechanical connection between said serpentine modules 1, 1 ', 1 ", 1 ' ", lnadvantageously occurs by means o f bare tubular elements 5, 5 ', 5", 5 ' ", 5X, hereinafter al so referred to as " intermodular connecting secti ons", arranged incl ined or vertically, without thereby departing from the scope of the present invention.

[0064] These tubular connecting sections 5, 5 ', 5", 5 ' ", 5X, are preferably arranged outside the cas ing 20, although this is not binding for the purposes of the present invention.

[0065] I f said tubular intermodular connecting sections 5, 5, 5 ', 5", 5Xare arranged outside the casing 20, they are advantageously provided with insulation, i. e. covered with a layer S of thermally insulating material ( not shown in the figures ), simi lar to the one provided for the insulation layer 30 of the casing 20 o f the reactor 100. The insulation layer S of these connecting tubular sections 5, 5 ', 5", 5 ' ", 5x can be determined in a similar way as for the layer 30 as will be explained in detail below.

[0066] The connection o f said tubular connecting sections 5, 5 ', 5", 5 ' ", 5x, and said serpentine modules 1, 1 ', 1", 1 ' ", lnis preferably made by means of flanges, although this is not binding for the purposes of the present invention.

[0067] As shown in f ig. 3, each module 1, 1 ', 1", 1 ' ", lnhas an inlet 4, 4 ', 4", 4 ' ", 4Xfor the hot fluid F and an outlet 6, 6 ', 6", 6 ' ", 6Xfor the fluid F or for the effluent E that has been produced by the thermal treatment of the f luid F.

[0068] The inlet 4 of the fluid F in the reactor 100 is connected to a supply tube ( not shown in the figure ) that feeds the f luid F to be thermally treated ( indicated in f ig. 3 with the arrow) to the reactor 100.

[0069] Said inlet 4 is advantageously arranged at the top, at the inlet o f the first module 1 arranged on top of the chamber 40, and higher than the other superimposed modules 1, 1 ', 1", 1 ' ", ln.

[0070] The outlet 6x of the ef f luent E from the reactor 100 is connected to a discharge tube (not shown in the figure ) to convey the effluent E ( indicated in fig. 3 with the arrow) out of the reactor 100 and downstream thereof.

[0071] Said outlet 6x is advantageously arranged at the bottom, at the outlet of the last module lnarranged at the bottom of the chamber 40 and lower than the other superimposed modules 1, 1 ', 1", 1 ' ", ln.

[0072] The aforesaid configuration with the inlet 4 at the top and the outlet 6x at the bottom is advantageous in that it is a draining configuration.

[0073] The material that can be used to make the serpentine modules 1, 1 ', 1", 1 ' ", lnis not binding for the purposes of the present invention, and mainly depends on the treatment temperature as well as on the type of feedstock to be treated.

[0074] It can be a metal material, preferably a metal material suitable to withstand high concentrations of free fatty acids and chlorides, such as the concentrations of free fatty acids and chlorides present in the aforesaid raw bio-feedstocks to be purified from metals and phospholipids by means of thermal treatments, possibly in the presence of water or acid / basic solutions.

[0075] Examples of materials adapted to produce the aforesaid modules 1, 1 ', 1", 1 ' ", lninclude stainless steels, preferably with a high Molybdenum content such as, for example, Alloy 904, 254SMO.

[0076] As mentioned above, the fluid F entering the at least one module 1 or the first module 1 of the plurality of modules 1, 1 ', 1", 1' ", lnmay advantageously be an oil-water emulsion / mixture or an emulsion / mixture of oil-organic acid aqueous solution, where the term " oil" refers to the raw bio-feedstock to be purified: in said oil-water or oil-organic acid aqueous solution emulsion / mixture, the volume ratio of oil / acidulated water or of oil / water may vary from 1 to 20, preferably less than 6.

[0077] This volume ratio can be calculated as the ratio of the respective volume flow rates, considering the density of the raw feedstock (oil ) and the density of the water / acidulated water as those measured at the mixing temperature of the raw feedstock and water / acidulated water, e. g. at T between 40 and 80 °C, generally 80 °C, although this is not binding for the purposes of the present invention and although they could be calculated at the T of the fluid F at the inlet in the reactor 100, e. g. 250 °C. Acids that can be used to form acidulated water include, for example, citric acid or other acids such as those used in the degumming process such as oxalic acid, or amidosulphonic acid, polycarboxylic acids ethylenediaminetetraacetic acid, phosphoric acid.

[0078] In a preferred embodiment, the acid is citric acid. The acid can be used in quantities such that the acid content is between 0. 5-7%, preferably between 1-5% by weight with respect to the weight of the acidulated water.

[0079] As mentioned above, the fluid F entering the first module 1 of the plurality of serpentine modules 1, 1 ', 1", 1 ' ", lnof the reactor 100 of the present invention is hot in that it has been preheated and has a defined temperature Tinat the inlet of the reactor 100 that is generally equal to, or substantially close to, the temperature that has been selected as effective for the thermal treatment for a given type of feedstock to be purified, for example between 150 °C and 270 °C.

[0080] This inlet temperature Tinof the fluid F entering the reactor 100 is achieved by subjecting the fluid F to a preheating to be carried out upstream of the reactor 100 and outside it, e. g. in a heat exchanger dedicated to this preheating.

[0081] The fact that the difference between the inlet temperature (Tin) of the fluid ( F) and the outlet temperature (Tout) of the effluent (E ) is less than or equal to a predetermined value for said thermal treatment in said reactor ( 100 ) is ensured by the configuration of the reactor 100 as described above due to the fact that the module 1 or the plurality of modules 1, 1 ', 1", 1 ' ", lnare arranged within the casing 20 insulated with a layer 30 of thermally insulating material which has a thickness such that a temperature difference between the inlet T of the fluid F in the reactor 100 and the outlet T of the effluent E (difference defined herein as AT ) is equal to or less than a predetermined value that has been deemed as acceptable to make the thermal reaction mainly occur and such as to ensure the desired process efficiency, e. g. ATMAX = 30 °C.

[0082] Thus, it is possible to avoid supplying additional heat to the fluid F by means of heat sources that are external to the reactor such as heat exchange fluids flowing inside the reactor or by means of heating means internal to the reactor such as electric coils wrapped around the tube through which the fluid passes in order to keep the inlet temperature constant.

[0083] The Applicant has in fact observed that it is possible to carry out a thermal and non-catalytic reaction of purification of a raw feedstock of renewable origin intended for the production of biofuels, limiting the dispersion into the atmosphere of the heat possessed by the fluid F entering the reactor 100, by appropriately dimensioning the insulation thickness 30 of the casing 20 so that the difference between the inlet temperature Tinof the fluid F and the outlet temperature Tout of the effluent E (hereinafter also referred to as AT of the fluid) is not greater than a predefined maximum value that has been assessed as acceptable to efficiently carry out the thermal reaction, e. g. 30-35 °C max, as indicated above.

[0084] In one embodiment, the difference between the inlet temperature Tinof the fluid F and the outlet temperature Tout of the effluent E is at most equal to 30 °C, preferably at least 5 °C, more preferably between 5°C and 25 °C.

[0085] Thanks to the reactor 100 of the invention as defined above, it is possible to avoid the use of - a heat transfer fluid circulating within the reactor in contact with the tubes; and / or

[0086] - tube insulation; and / or

[0087] - electrical heating coils (e. g. electrical tracings, heating cables ) inside the reactor and wrapped around the tubes.

[0088] Once defined the type of raw feedstock, the inlet temperature Tinand outlet temperature Tout that are acceptable to make the thermal reaction of purification occur, and once identified the insulation material and its thermal conductivity coefficient, it is possible to define the thickness 30 by means of calculations that are known to the person skilled in the art.

[0089] An example of a thermally insulating material that can be used in the reactor 100 of the present invention may be stone wool, although this is not binding for the purposes of the present invention.

[0090] In one embodiment, the layer 30 of this thermally insulating material or insulation of the reactor 100 is such as to have a temperature difference between the inlet of the fluid into the reactor and the outlet of the fluid ( i. e. effluent) from the reactor 100 of less than 30 °C, although this is not binding for the purposes of the present invention.

[0091] The inert gas contained in the internal chamber 40 of the casing 20 eliminates the presence of oxygen, thus acting as an inertiser, particularly in the event of fluid F leaking from the modules. This inert gas may advantageously be nitrogen and / or other types of inert gases, without thereby departing from the scope of the present invention. This inerting atmosphere then surrounds all of the serpentine modules 1, 1 ', 1", 1 ' ", lnwhich are housed inside the chamber 40 of the casing 20.

[0092] Said chamber 40 contains neither heat storage elements such as graphite, nor heat exchange fluids so that all of the serpentine modules housed inside the chamber 40 of the casing 20 are not immersed in a heat exchange fluid or in contact with heat storage element.

[0093] The number of modules 1, 1 ', 1", 1 ' ", lndepends on the overall length required to meet the process constraints, in terms of residence time of the fluid F (reactant feedstock) therein.

[0094] The diameter of the tubes 2 and curves 3 depends on the linear fluid speed F and the hourly flow rate that has been defined to have a certain daily output of purified feedstock.

[0095] The linear speed of the fluid F within the serpentine modules 1, 1 ', 1", 1 ' ", lnhas a value such as to avoid solids, which can be formed in heat treatment, from being deposited along the tubular modules of the reactor.

[0096] In one embodiment this speed is 1-2 m / s.

[0097] The expression " Residence time", "dwell time" herein means to identify the ratio between the total volume V (expressed in m3) defined by the serpentine modules 1, 1 ', 1", 1 ' ", lncontained in the reactor 100, and the volumetric flow rate (expressed in m3 / h) of the fluid F fed into the reactor 100, e. g. acidulated aqueous emulsion containing the raw bio-feedstock.

[0098] In one embodiment, the residence time is 3-7 minutes. In another embodiment, the residence time is 1-5 minutes. In one alternative embodiment, the residence time is 1-7 minutes and the linear speed 1-2 m / s: using these values, it is advantageously possible to determine the diameter of the tubes 2 and curves 3 that form the one or more serpentine modules 1, 1 ’, 1", 1 ' ", In and the overall length of the total module development.

[0099] The thickness of the tubes 2 and curves 3 forming the serpentine modules 1, 1 ', 1", 1 ' ", lnis not binding and depends essentially on the design pressure of the thermal treatment process.

[0100] The pressure at which the above-mentioned thermal treatment is conducted is selected in such a way that the water / acidulated water of the fluid F is liquid in the reactor at the selected working temperature ( single-phase liquid system).

[0101] Alternatively, the pressure at which the above-mentioned thermal treatment is conducted is selected in such a way that water / acidulated water of the fluid F partially vaporises inside the reactor.

[0102] In one embodiment, the pressure at which the treatment process generally takes place by means of thermal purification reaction of the raw feedstock of renewable origin is, advantageously, ranging from 10 barg to 50 barg.

[0103] The reactor 100 can also be provided with a system to control the parameters of the process occurring therein, such as temperature and pressure.

[0104] In particular, the reactor 100 may be provided with a control system that may include one or more of the following detection / adjustment tools

[0105] - probes for measuring the surface T of the tube, e. g.

[0106] at the reactor inlet and outlet;

[0107] - probes for measuring the T inside the chamber 40 and the air outside the casing 20;

[0108] - transmitter of Pressure inside the casing 20;

[0109] - safety valves for overpressure inside the casing 20 with respect to the atmospheric pressure.

[0110] The reactor 100 of the invention can be brought to process temperature during a transient period in various ways known to the person skilled person in the art, for example by making a hot auxiliary fluid, e. g. water, pass through the modules, so that the surface of the serpentine modules reaches a temperature substantially equal to the reaction temperature that has been selected.

[0111] The advantages of the reactor 100 according to the present invention are numerous.

[0112] Compared to reactors consisting of one or more tubes surrounded by a heat-exchange fluid such as hot oil, the present reactor 100 has the advantage that it does not need this heat-exchange fluid to circulate inside the reactor, simplifying the reactor construction, even compared to the case of a reactor having j acketed tubes.

[0113] In addition, the aforesaid multi-module serpentine configuration does not advantageously require a heat exchange fluid, which is normally fed under pressure to circulate on the surface of the modules. In fact, this reactor is at atmospheric pressure because the inerting gas contained in the chamber 40 is at atmospheric pressure.

[0114] In addition, although the reactor 100 has pressure drops of a few bars, e. g. 5 bar maximum, this is not detrimental to the thermal purification treatment as this process does not depend on the pressure, as long as one works in a range of Pressure wherein the water or acidulated aqueous solution, if used, remain liquid at the selected reaction I.

[0115] It is also advantageous that by subjecting the fluid F to a temperature drop that is limited within the reactor 100 of the present invention, it is possible to recover from the effluent E leaving the reactor 100 a large part of the thermal capacity that has been provided to the entering fluid F, thereby maximising the thermal recovery from the effluent E in equipment downstream the reactor 100, thereby limiting the operating costs of the plant comprising the reactor 100 according to the present invention.

[0116] As stated above, it can be provided a second embodiment of the heat treatment reactor 100 in accordance with the present invention, wherein each of said continuous tubular elements 1, 1 ', 1", 1 ' ", lnhaving a serpentine development placed in a respective horizontal plane has a respective casing 20 thermally insulated from the outside by means of the layer 30 of thermal insulating material.

[0117] More generally, in said second embodiment of the reactor 100, it is provided a respective casing ( for example, but not limiting, in the form of parallelepiped) to each module so that each module is thermally insulated with respect to the external environment and with respect to the other modules included in the reactor.

[0118] Said casing 20 is advantageously in the form of a parallelepiped but this is not limiting for the scope of the present invention, and it acts as structure of containment of the heat with respect to the outside because it is coated, generally on the inner side, with said thermally insulating material described above.

[0119] All the features above described for the first embodiment can be reproduced in said second embodiment except those described here below.

[0120] In this second embodiment, each casing of each serpentine module is physically separated from the other casings of the other modules.

[0121] Moreover, in this second embodiment it can be provided, inside each casing, optional electrical resistances for the respective serpentine module.

[0122] In addition, in this second embodiment it can be provided optional electrical resistances on the surface of each tube.

Claims

CLAIMS1. Reactor ( 100 ) for the thermal treatment of puri f ication, by means o f a non-catalytic reaction, o f a f luid ( F) compri sing at least one raw feedstock of renewable origin, intended for the production o f bio fuels, and poss ibly water or an acid / bas ic aqueous solution, wherein said reactor ( 100 ) compri ses- one or more continuous tubular elements ( 1; 1 '; 1"; 1 ' ";ln) arranged, each, in a respective hori zontal pl ane and in fluid communication with each other, each o f said continuous tubular elements having a serpentine development in s aid respective hori zontal plane and a bare surface, said one or more tubular elements de fining a reaction volume (V) o f said reactor ( 100 );- an inlet ( 4 ) of said fluid ( F) having a predetermined inlet temperature ( Tin) in said reactor ( 100 );- an outlet ( 6x ) of an effluent ( E ) compri sing said feedstock o f renewable origin in puri f ied form, said effluent (E ) having an outlet temperature ( Tout) from said reactor ( 100 );a cas ing ( 20 ) de f ining an internal chamber ( 40 ) in which said one or more tubular elements ( 1; 1 '; 1"; 1 ' "; ln) having a serpentine development are arranged, said internal chamber ( 40 ) being further fi lled with an inert gas having a temperature ranging from Tinto Tout, said cas ing ( 20 ) being covered by a layer ( 30 ) of thermal insulation material with respect to the outside;said reactor ( 100 ) being devoid of heating means to supply heat to said fluid ( F) pas sing through said reactor ( 100 ); andsaid layer ( 30 ) o f thermal insulation material having a thicknes s such that, in use, the value o f the di f ferencebetween the inlet temperature ( Tin) of the f luid ( F) and the outlet temperature ( Tout) of the effluent (E) is less than or equal to a predefined value for said thermal treatment in said reactor ( 100 ).

2. Reactor according to claim 1, wherein said casing ( 20 ) i s an I SO container, or is a cage structure composed of a plural ity o f hori zontal and vertical beams ( 200 ) equipped with external panels.

3. Reactor according to claim 1 or 2, wherein said continuous serpentine modules ( 1, 1 ', 1", 1 ' ", ln) are arranged superimposed and spaced from each other along the vertical.

4. Reactor according to any one o f the preceding claims, wherein each continuous module ( 1, 1 ', 1", 1 ' ", ln) is composed of a plurality o f straight tubes ( 2 ) and a plural ity of curves ( 3 ) having a 180 ° curvature, wherein the straight tubes ( 2 ) alternate with the curves ( 3 ) and are in f luid communication with each other.

5. Reactor according to any one o f the preceding claims, wherein said serpentine modules ( 1, 1 ', 1", 1 ' ", ln) are connected in series with each other and in f luid communication with each other by means of tubular elements ( 5, 5 ', 5", 5 ' ", 5X) arranged external ly to said cas ing ( 20 ) and covered with a layer ( S ) of thermal insulation material.

6. Reactor according to any one o f the preceding claims, wherein the thermal insulation material of the layer ( 30 ) i s rock wool.

7. Reactor according to any one o f the preceding claims, wherein the inlet ( 4 ) and the outlet ( 6x ) are arranged in such a way as to form a draining reactor conf iguration.

8. Reactor according to any one o f the precedingclaims, wherein said serpentine modules ( 1, 1 ', 1", 1 ' ", ln) are made of stainless steel, preferably with high molybdenum content, more preferably in Alloy 904, 254SMO.

9. Reactor according to any one of the preceding claims, wherein the difference between the inlet temperature (Tin) of the fluid ( F) and the outlet temperature ( Tout) of the effluent (E) is at most equal to 30°C.

10. Reactor according to any one of the preceding claims, wherein the reaction temperature ranges from 150 °C to 280 °C or from 200 to 300 °C.

11. A reactor according to any one of preceding claims, wherein the non-catalytic reaction occurring in said reactor is non-exothermic.

12. Non-catalytic thermal treatment process for the purification of at least one raw feedstock of renewable origin intended for the production of biofuels, said process comprising the steps of- placing said raw bio-feedstock in contact with water or acidulated water to form a fluid in the liquid phase, preferably a fluid in the form of an aqueous emulsion;- subjecting said fluid in the liquid phase to a thermal treatment in a reactor, at a temperature of 200-300 °C, preferably 230 °C-260 °C, for a residence time up to 30 minutes, preferably between 1 minute and 5 minutes, operating at a pressure greater than 10 barg up to 65 barg, preferably between 45 and 55 barg, obtaining an effluent at the outlet of said reactor comprising said purified bio-feedstock;- subjecting said effluent to at least one non-adsorptive physical separation to separate said metal contaminants including phosphorus from said effluent containing the purified bio-feedstock;- wherein said reactor is a reactor ( 100 ) as defined in anyone o f the preceding claims and compri ses one or more continuous tubular elements ( 1; 1 '; 1"; 1 ' "; ln) arranged, each, in a respective hori zontal plane and in f luid communication with each other, each of said continuous tubular elements having a serpentine development.

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