LOW FRICTION FIXING FOR ROTATING HEAT EXCHANGER TUBE INSERT

Abstract

The present invention relates to a low-friction fastening device for a rotating, movable insert for a heat exchanger tube. Such inserts are used to improve heat transfer efficiency and / or reduce fouling of heat exchanger tubes in industrial units, for example, units used in petroleum refining, petrochemicals, or the chemical industry in general. The fastening device comprises a bearing-type mounting support (130) for a trunnion (120), and at least one low-friction wear-resistant element (150) having a longitudinal cross-section shaped to reduce friction with a head (14', 141) of the trunnion and / or an additional wear-resistant element, said longitudinal cross-section being circular, semi-circular, or frustoconical. Figure 3 to be published

Description

Title of the invention: LOW FRICTION FIXING FOR ROTATING HEAT EXCHANGER TUBE INSERT technical field

[0001] The present invention relates to the field of inserts for tubular heat exchangers used to improve heat transfer efficiency and / or reduce fouling of heat exchanger tubes in industrial units, for example, units used in oil refining, petrochemicals, or the chemical industry in general. In particular, the present invention relates to a device for securing a rotating, movable insert for a tubular heat exchanger, configured to minimize friction within said securing device during the operation of the insert and thus facilitate its rotation. Previous technique

[0002] Heat exchanger insert technologies are used to improve heat transfer efficiency and reduce fouling of industrial heat exchanger tubes.

[0003] In many fields, such as oil refining, petrochemicals, and other fields of chemistry, food processing, and energy, industrialists are indeed concerned with optimizing heat transfer in the heat exchangers used, but also confronted with the problem of deposits in said exchangers, which may come from impurities present in the liquid streams from various processes that pass through the heat exchangers, and / or from the decomposition or formation of organic products such as polymers or hydrocarbons and mineral products in said liquid streams.

[0004] These may be suspended impurities accumulating, deposits of mineral salts dissolved in liquid streams, coke forming, or sulfur compounds soluble in hydrocarbon streams. These deposits can be generated by excessive fluid temperatures or result from corrosion. These deposits, which gradually accumulate on the walls of the heat exchanger tubes over time, impair the performance of the heat exchangers, which thus lose efficiency over time. The deposits form a solid substance with low thermal conductivity which has the effect of insulating the walls and reducing heat transfer in the exchanger, ultimately damaging the energy efficiency of the industrial processing or manufacturing unit in question implementing the heat exchanger. Another consequence of the formation of these deposits on the internal walls of heat exchanger tubes can be reduced flow rates, which are detrimental to the proper functioning of the downstream process, and / or hot spots on the tube's internal surface. These restrictions and / or hot spots can lead to deterioration of the tube structure and thus cause product leaks that can be hazardous to the operator and / or equipment.

[0005] The use of inserts in heat exchangers is thus aimed at improving heat transfers, because the inserts promote turbulence which leads to a reduction in the thermal boundary layer, which decreases the resistance to heat transfer and therefore improves the efficiency of heat transfer, and at preventing fouling of the heat exchangers.

[0006] The use of inserts is a very interesting and promising solution for reducing energy consumption and, consequently, CO2 emissions from industrial processes using heat exchangers, as is the case in all the fields mentioned above. In the field of oil refining, for example, there are many units using heat exchangers that are susceptible to fouling. Refining crude oil by preheating it with the hot atmospheric residue exiting an atmospheric distillation unit is one example. Many so-called heavy crude oils are very rich in asphaltenic compounds that can form sediments, as well as in sulfur and other corrosive compounds that are prone to depositing on the internal walls of the heat exchanger tubes through which they circulate.

[0007] There are many different forms of inserts in the industry, such as a winding of a metal wire, a twisted band, a central shaft with blades, said inserts being able to include moving and / or static parts, and being able to be fixed or not to the tube, and where appropriate in different ways, for example on one end only or at both ends of the tube. Two main types of inserts for tubular heat exchangers can be distinguished: static inserts and rotating inserts driven by the flow of fluid through the tube. Both types promote heat transfer and reduce fouling. However, rotating inserts generally offer better performance, both in terms of fouling reduction, thanks to the mechanical effect of the insert's rotation, and in terms of pressure drop, a crucial factor for insert performance. The presence of the insert, which occupies part of the tube, increases resistance to fluid flow, which can be problematic if this resistance is excessive. Typically, this results in a significant pressure drop. This affects the capacity and energy consumption of the pumps and turbines that circulate the fluid(s) and compensate for the pressure drop. Therefore, a minimal pressure drop is generally desired, meaning one that is less than the pressure drop of a tube without an insert, in order to avoid compromising the heat exchanger's energy efficiency and even to avoid having to replace the fluid circulation equipment upstream of the exchanger. A rotating insert generally induces less pressure drop than a fixed insert, for example, up to 40% less.

[0008] An example of a rotating insert for a heat exchanger tube is described, for instance, in patent FR2569829. The insert comprises a rigid, solenoid-shaped metal winding that is rotated by the fluid flowing in the tube. The rigid insert is configured to allow the movable winding to rotate freely about the axis of the tube. The pitch of the metal winding can be fixed or variable.

[0009] Figure 1 illustrates a known rotating insert of this type, comprising a rigid helical metal winding 20 having a plurality of turns of length L, diameter D, pitch p, and angle of inclination α(a) defined with respect to the central axis of the winding coinciding with the axis Z of the heat exchanger tube in which the insert is mounted. The metal rod forming the winding has a thickness e. The metal winding has a free end and an end fitted with a ring serving as a connection point with a known fastening device 10 for the insert. The fastening device 10 is shown in more detail in Figure 2. It comprises a rotating trunnion 12 having at one end a hook 11 through which the ring of the metal winding of the movable insert passes. The rotating trunnion 12 is taken in the orifice of a bearing 13 and allows the insert to rotate freely about itself around the axis of the exchanger tube.The bearing 13 consists of a stirrup-shaped portion 13a, the ends of which are in the form of two arms for attachment to the tube (tube not shown), and a central portion 13b with an opening for retaining the trunnion 12. The ends 13c of the two arms 13a have lugs 2 that engage with the tube and shoulders 2' that rest on the open end of the tube. At its end opposite the hook, the trunnion 12 has a head 14, for example tubular, for retaining it within the bearing 13. Anti-wear washers (15, 16) can be positioned between the bearing 13, particularly the central portion of the bearing 13b, and the head 14 of the trunnion 12.An anti-wear washer 15 can be fixed to the central part of the bearing and be integral with it, thus also acting as a stop to help maintain the trunnion rod 12 in the axis of rotation of the moving element and to stabilize it, and can therefore preferably be relatively elongated. An anti-wear washer 16 can... The anti-wear washer is positioned between the anti-wear washer 15 and the head 14 of the trunnion 12 to further limit wear on the other parts. The anti-wear washer is free, meaning it is not attached to either the moving element (the trunnion attached to the moving insert) or the fixed element formed by the bearing. When the moving element is rotated by the fluid flowing through the tube, the head 14 attached to the trunnion 12 comes into frictional contact either with the anti-wear washer 15 attached to the fixed element, or with the intermediate anti-wear washer 16 if such a washer is provided, which itself has a contact surface in friction with the anti-wear washer 15 attached to the fixed element. A similar fastening device is described, for example, in patent FR2639425, patent FR2612267, or patent FR2890162, comprising a trunnion head and one or more anti-wear washers.The trunnion head can have hemispherical flanks, as disclosed in patents FR2639425 and FR2612267. The problem of wear and friction on the metal parts of the mobile insert fastening device is therefore known and is addressed, in particular, by the use of anti-wear washers. In patent FR2890162, a technical solution to the problem of wear and friction on the metal parts of the mobile insert fastening device is a flexible coupling positioned between the metal winding of the mobile insert and the trunnion of the fastening, limiting trunnion misalignment and the resulting wear on the metal parts of the fastening. However, such a flexible coupling constitutes an additional component that can be costly and involves additional connection points that can also introduce mechanical weaknesses into the entire system.

[0010] A problem often encountered when using rotary inserts is a lack of flexibility regarding the possible operating range of the fluid flow velocity in the tube: their operation is generally optimal only within a limited range. Indeed, the mechanical effect provided by the rotation of the insert decreases rapidly when the flow velocity is low, typically below approximately 1 m / s, resulting in lower insert efficiency in reducing fouling (and therefore heat transfer) and a greater pressure drop.

[0011] This lack of flexibility is therefore detrimental to addressing a wide range of fluids circulating in heat exchangers, and especially fluids with low flow rates such as certain heavy hydrocarbon loads which can, for example, be particularly viscous under given temperature and pressure conditions, or in the event of fluctuation in the flow rate or viscosity of the circulating fluid, linked to changes in the nature / composition of the circulating fluids or operating conditions leading to a slowing down of the circulating fluid. Objectives and Summary of the Invention

[0012] The present invention aims to overcome, at least in part, the prior art problems described above, and in particular to improve the operational flexibility of a rotary tubular heat exchanger insert, specifically to provide an insert that can be operated at low fluid flow velocities in the tube, typically at flow velocities below 1 m / s, to ensure a mechanical effect by rotating it at these low flow velocities. It is thus proposed to provide a rotary insert with a low rotation threshold, enabling it to operate at low fluid flow velocities in the tube.

[0013] Another objective is to extend the service life of inserts for rotary tubular heat exchangers, and in particular to provide a fixing device for an insert for a rotary tubular heat exchanger that is stable and robust, and that can also advantageously be of limited size.

[0014] In general, the present invention aims to provide a device for reducing fouling and / or improving heat exchange for heat exchanger tubes that is robust (risk of breakage minimized), that limits pressure losses while being able to be used at low fluid flow velocities in the tube.

[0015] Thus, to achieve at least one of the aforementioned objectives, among others, the present invention proposes, according to a first aspect, a device for fixing an insert comprising a rotating movable element for a heat exchanger tube, said fixing device comprising: - a mounting support forming a bearing for a trunnion, said mounting support comprising a central part provided with an opening and at least two fixing feet made of a rigid material capable of elastic deformation, mounted on said central part and capable of being forcefully engaged at an open end of the tube to bear elastically against an internal wall of said tube, - said trunnion comprising a rod (preferably straight cylindrical) elongated along an axis Z engaged in the opening of said central part and a head at one end of said rod, said head being disposed on the side of said central part intended to be oriented towards the outside of the tube, the other end of said trunnion rod being able to be made integral with the rotating movable element of the insert, - at least one low-friction wear-resistant part disposed between said central part and the head of the trunnion, characterized in that said low-friction wear-resistant part has a longitudinal section, along the axis Z, of a shape adapted to reduce friction between said low-friction wear-resistant part and the head of the trunnion and / or a wear-resistant part additional, said longitudinal section being circular, semi-circular, or frustoconical.

[0016] According to one or more embodiments, the trunnion head comprises a semi-circular or circular longitudinal section in contact with the circular, semi-circular or frustoconical longitudinal section of said reduced friction wear-resistant part so as to reduce the friction between said trunnion head and said reduced friction wear-resistant part.

[0017] According to one or more embodiments, the trunnion head is a ball.

[0018] According to one or more embodiments, the device comprises a single piece reduced friction wear-resistant piece in contact with and fixed securely to the central part of the bearing, and said single reduced friction wear-resistant piece has a semi-circular or frustoconical longitudinal section in contact with said journal head so as to reduce friction between said journal head and said single wear-resistant piece.

[0019] According to one or more embodiments, the device includes at least one additional anti-wear part disposed between said reduced-friction anti-wear part and the central part of the bearing.

[0020] According to one or more embodiments, said reduced friction anti-wear part is a ball.

[0021] According to one or more embodiments, said at least additional anti-wear part has reduced friction.

[0022] According to one or more embodiments, the device includes a low-friction wear-resistant part forming a first ball in contact with the head of the trunnion, and two additional low-friction wear-resistant parts, one of them forming a second ball in contact with the first ball.

[0023] According to one or more embodiments, said at least one reduced friction anti-wear part is a ball, preferably with a diameter less than the largest dimension of the cross-section of said trunnion head and / or said additional anti-wear part.

[0024] According to one or more embodiments, the device comprises three or four fixing feet, each foot having at its end opposite the central part of the bearing a lug surmounted by a shoulder, said lug and said shoulder having an external surface curved in an arc of a circle adapted to follow the curvature of the internal wall of the heat exchanger tube.

[0025] According to one or more embodiments, the device comprises four fixing feet.

[0026] According to one or more embodiments, the device comprises two fixing feet, each foot having at its end opposite the central part of the bearing a lug surmounted by a shoulder, and in which said lug and said shoulder have a curved external surface suitable for following the curvature of the internal wall of the heat exchanger tube, and said shoulder forms an arc of a circle with a larger opening than the arc of a circle formed by said lug, or in which said lug is rectangular and surmounted by a flat shoulder, said lug having an end piece having a curved external surface suitable for following the curvature of the internal wall of the heat exchanger tube.

[0027] According to one or more embodiments, said at least one reduced friction wear-resistant part comprises a material with a coefficient of friction lower than that of the material forming the trunnion head and / or the central part of the fixing support, preferably phosphor bronze, preferably in association with stainless steel, titanium, Hastelloy®, or Inconel®, or brass, and more preferably phosphor bronze in association with stainless steel or titanium.

[0028] According to a second aspect, the present invention relates to an insert for a heat exchanger tube, comprising a fastening device according to the invention and a rotating movable element comprising a rigid helical winding of a rod (preferably metallic) comprising several turns, said rotating movable element comprising: - a first end fixed to the trunnion of said fastening device allowing the free rotation of said moving element about itself around the Z axis of said tube under the action of a fluid passing through said tube, and - a second free end.

[0029] According to one or more embodiments, the rotating moving element further comprises a rotating drive part disposed between said fixing device and said rigid helical winding, and connected in a fixed rotational manner with said rigid helical winding and said trunnion of the fixing device, said rotating drive part comprising a shaft coaxial with said rigid helical winding and provided with at least two blades fixed to said shaft.

[0030] According to one or more embodiments of the invention, the rotating drive part is in the form of a screw with a pitch p3 between 10 mm and 50 mm, has four blades, and has a length L3 between 10 mm and 500 mm.

[0031] According to one or more embodiments of the invention, the rigid helical winding is constituted by a single section of turns with a fixed pitch p.

[0032] According to one or more embodiments of the invention, the rigid helical winding consists of a first portion of length L1 originating from the side of the first end of the moving element, and a second portion of length L2 extending from the first portion, the first pitch pl of the turns of the the first portion being smaller than the second pitch p2 of the turns of the second portion, the pitch pl being between 5 mm and 20 mm, the pitch p2 being between 10 mm and 60 mm, and the length L1 being preferably between 100 mm and 3000 mm, preferably between 200 mm and 1000 mm.

[0033] According to one or more embodiments of the invention, the insert has a total length between 50% and 100% of the total length LT of the heat exchanger tube.

[0034] According to a third aspect, the present invention relates to a heat exchanger comprising a plurality of tubes through which a fluid passes, comprising an insert having a fastening device according to the invention, fixed to the upstream end of at least one of said tubes.

[0035] According to a fourth aspect, the present invention relates to the use of a fastening device and an insert according to the invention for a tubular heat exchanger, for preheating crude oil in an atmospheric distillation process of said crude oil, or for preheating a hydrocarbon feed in a hydroconversion or hydrotreating process of said hydrocarbon feed, or for evaporating or condensing a fluid in a nuclear power plant.

[0036] Other objects and advantages of the invention will become apparent from the following description of particular embodiments of the invention, given by way of non-limiting examples, the description being made with reference to the attached figures described below. List of figures

[0037] [Fig.1]

[0038] Fig. 1, already described above, represents an insert and its method of attachment to the heat exchanger tube according to the prior art.

[0039] [Fig.2]

[0040] Fig. 2, already described above, represents another view of the known fastening device of the insert illustrated in Fig. 1.

[0041] [Fig.3]

[0042] Fig. 3 represents schematic cross-sectional views of examples (3A, 3B) of a reduced friction fastening device according to an embodiment of the invention comprising a single wear-resistant part which has reduced friction.

[0043] [Fig.4]

[0044] Fig. 4 represents schematic cross-sectional views of examples (4A, 4B, 4C) of a low-friction fastening device according to an embodiment of the invention comprising two anti-wear parts, at least one of which is low-friction.

[0045] [Fig.5]

[0046] Fig. 5 is a schematic cross-sectional view of an example of a reduced friction fastening device according to an embodiment of the invention comprising three anti-wear parts which are of reduced friction.

[0047] [Fig.6]

[0048] Fig. 6 is a three-dimensional (3D) schematic view of an example of a low-friction fastening device according to an embodiment of the invention comprising four fastening feet.

[0049] [Fig.7]

[0050] Fig. 7 is a schematic 3D view (side view 7A and bottom view 7B) of an example of a low-friction fastening device according to an embodiment of the invention comprising three fastening feet with rounded ends.

[0051] [Fig.8]

[0052] Fig. 8 is a schematic 3D view of an example of a low-friction fastening device according to an embodiment of the invention comprising four fastening feet with rounded ends.

[0053] [Fig.9]

[0054] Fig. 9 is a schematic 3D view (three-quarter view 9A and bottom view 9B) of an example of a low-friction fastening device according to an embodiment of the invention comprising two fastening feet with rounded ends and an enlarged shoulder.

[0055] [Fig. 10]

[0056] Fig. 10 is a schematic 3D view (three-quarter view 10A and bottom view 10B) of an example of a low-friction fastening device according to an embodiment of the invention comprising two fastening feet having lugs with rounded tips.

[0057] [Fig.11]

[0058] Fig. 11 is a schematic 3D view of an example of an insert and its low-friction fastening system in a heat exchanger tube according to an embodiment of the invention in which the insert includes a rotating drive part.

[0059] [Fig. 12]

[0060] Fig. 12 is a schematic 3D view of an example of an insert according to an embodiment of the invention in which the insert comprises a rotating drive part and a rigid helical winding with an initial section of tight pitch.

[0061] [Fig. 13]

[0062] The [Fig. 13] is a diagram of the rotational speed VR (RPM) of the insert as a function of the normalized liquid velocity (VSL / VSL_ref) of an example of an insert according to the prior art (A) and an example of an insert according to the invention (B).

[0063] In the figures, the same references designate identical or analogous elements. Description of the implementation methods

[0064] In this description, the term "include" is synonymous with (means the same as) "comprise", "include", and "contain", thus being inclusive or open, and not excluding other elements not mentioned. It is understood that the term "include" includes the exclusive and closed term "consist".

[0065] In this description, the expression "between ... and ..." means that the limit values ​​of the interval are included in the range of values ​​described, unless otherwise specified.

[0066] Furthermore, in this description, the terms "essentially" or "substantially" or "approximately" with respect to a reference value correspond to an approximation of ±10%, ±5%, preferably ±1%, most preferably ±0.5%. This may be a value of temperature, pressure, distance, speed, flow rate, content of compound(s), etc.

[0067] In the present description, the various parameter ranges characterizing a given device, or relating to a step in a process implementing said device, such as ranges relating to dimensions (lengths, diameters, etc.), angles, pressure ranges, or temperature ranges, may be used alone or in combination. For example, in the sense of the present invention, a preferred range of pitch values ​​for the turns of the rigid helical winding of the insert may be combined with a more preferred range of length values ​​for the rigid helical winding.

[0068] In this description, when mentioned, the positions "front", "rear", "horizontal", "vertical", etc., of the various elements of the fastening device, the insert, and the heat exchanger tube are defined with respect to a tubular heat exchanger in its operating position and with respect to the direction of fluid flow through the heat exchanger tube. The direction of fluid flow is represented by a solid arrow in the figures.

[0069] In this description, the fluid flow velocity in the tube refers to the surface velocity of the fluid flowing in the tube V_SF, commonly understood to be the ratio between the volumetric flow rate of the fluid Q and the internal cross-section of the tube S: V_SF = Q / S. The same applies to the threshold speed for starting rotation of an insert, which is a surface velocity, more precisely a specific value of V_SF particular to the insert used.

[0070] In this description, "rigid" means, with reference to a helical winding of a rod of an insert, preferably metallic, a winding that does not does not deform, or hardly deforms, irreversibly under the action of the fluid that rotates the moving part containing said winding, under normal operating conditions of the heat exchanger tubes. In particular, said winding is not, or hardly deformed, irreversibly when the circulating fluid exhibits variations in speed, viscosity, and / or temperature.

[0071] In this description, a tube-side heat exchanger or tubular heat exchanger is defined as a heat exchanger comprising at least one tube inside which flows a fluid commonly referred to as the "tube-side fluid," exchanging heat with a fluid flowing outside said tube. The heat exchangers referred to in the present invention are classically shell-and-tube heat exchangers in which the tube-side fluid flows inside a set of parallel tubes called a tube bundle. These tubes are enclosed in a shell called a shell. The other fluid, called the "shell-side fluid," flows inside the shell but outside the tubes. The flow of the fluids on the tube and shell sides can be co-current and / or counter-current. The tubes are often very long, typically up to 6 m, and of small diameter to optimize the surface area to volume ratio.They are generally held at their ends in perforated plates called tube sheets, which serve to support the tubes and also to separate fluids, and may be supported between the tube sheets by intermediate support plates (perforated plates transverse to the tubes). The tubes may also be U-shaped, and their ends may, for example, be attached to a single tube sheet.

[0072] In this description, the pitch of a helical winding comprising several turns is understood by the commonly accepted definition, which is the distance measured between the centers of two turns. In a two-dimensional representation, it is the distance between two crests on the same side of the winding axis, and in a 3D representation, it is the length (distance) between two turns around the axis of revolution of the turn (or the distance traveled along the axis of revolution of the turn to make one complete turn).

[0073] In this description, the longitudinal section of a part means the section along the length of said part. In the case of the parts consisting of the trunnion head and the wear-resistant parts of the fastening system according to the invention, this refers to the section along the longitudinal axis of the fastening device, and in particular of the trunnion shank, which coincides with the axis of the Z-tube. In the specific case of a ball, the longitudinal section is identical to the transverse section (orthogonal to the Z-axis).

[0074] Embodiments of the insert fastening device, of the insert itself comprising such a fastening device, its use in a heat exchanger and their applications are described in detail below. Many specific details are given to provide a more thorough understanding of the invention. However, it will be apparent to those skilled in the art that the insert fastening device, the insert incorporating such a fastening device, the heat exchanger incorporating such an insert, and their use can be implemented without necessarily all of these specific details. In other cases, well-known features have not been described in detail to avoid unnecessarily complicating the description.

[0075] In the present description, the different embodiments presented can be implemented separately or in combination with each other, without limitation of combinations when this is technically feasible.

[0076] The present invention proposes a low-friction fixing device for an insert comprising a rotating movable element for a heat exchanger tube.

[0077] Figures 3 to 5 represent different configurations of the reduced friction wear-resistant part(s), while figures 6 to 9 illustrate different possible configurations of the feet of the reduced friction fastening device.

[0078] Reference is made below to Figures 3 to 5, which represent examples of embodiments of the insert fastening device according to the invention, to describe in general terms said low-friction fastening device, without the specific features of the embodiments illustrated in these Figures 3 to 5 limiting the invention. These specific features are detailed below with a particular description of each figure.

[0079] Thus, the insert fixing device according to the invention comprises: - a mounting support 130 which forms a bearing for a trunnion 120, the mounting support comprising a central part 130b having an opening and at least two mounting feet 130a of a rigid material capable of elastic deformation, mounted on said central part and capable of being forcefully engaged at an open end of the tube to bear elastically against an internal wall of said tube, - the trunnion 120, which comprises a rod elongated along an axis Z, engaged in the opening of the central part and a head (14, 14', 141) at one end of the trunnion rod, said head being disposed on the side of the central part 130b intended to be oriented towards the outside of the tube, the other end of the trunnion rod being capable of being made integral with the rotating movable element of the insert, - at least one low-friction wear-resistant part (150, 160, 161) disposed between said central part 130b and the head (14, 14', 141) of the trunnion 120. According to the invention, said low-friction wear-resistant part comprises a longitudinal section, i.e., a section along the Z-axis, with a shape adapted to reduce friction between the low-friction wear-resistant part and the head of the journal and / or a additional anti-wear part, said longitudinal section being circular, semi-circular, or frustoconical.

[0080] The rotating trunnion 120 includes, for example, at one end a hook 110, or any other fastening means, through which passes a ring, or any other means of fastening the moving element of the insert, typically the metal winding of the moving element of the insert. The rotating trunnion 120 is held in the opening of a bearing-forming member 130, also referred to herein as a mounting support 130, and allows the free rotation of the moving element of the insert about itself around the axis of the heat exchanger tube. The trunnion 120 may comprise, or even be made of, at least one of the following materials, alone or in mixture: stainless steel, such as 303, 316L, or 304 stainless steel, titanium, a mixed stainless-titanium metal alloy (including in the form of a coating).

[0081] The trunnion head (14, 14', 141) may comprise, or even be made of, at least one of the following materials, alone or in mixture: stainless steel, such as 303, 316L, or 304 stainless steel, titanium, a mixed stainless-titanium metal alloy, or any other metal or metal alloy material such as Hastelloy® alloy.

[0082] According to the invention, the bearing 130 may be identical to that described in relation to [Fig. 2], which represents a prior art fastening device. Compared to the fastening device of [Fig. 2], only the parts formed by the trunnion head and the wear-resistant parts arranged between the trunnion head and the bearing differ. The bearing 130 may also be different from the bearing 13 illustrated in [Fig. 2], and may, for example, conform to the bearings of the embodiments shown in Figures 6 to 10.

[0083] The bearing 130 consists of the central part 130b which is provided with the opening, preferably centered along the Z axis, for retaining the trunnion 120, and on which are mounted at least two fixing feet 130a, formed of a rigid material capable of deforming elastically and of being forcefully engaged at an open end of the tube to bear elastically against an internal wall of the tube, allowing attachment to the tube conduit (tube not shown). The bearing 130 may comprise, or even be made of, at least one of the following materials, alone or in a mixture: carbon steel, steel with an anti-corrosion treatment (e.g., galvanized steel), stainless steel, such as 303, 316L, or 304 stainless steel, or any other metal or metal alloy material such as Inconel® or Hastelloy® alloy that is resistant to high temperatures and corrosion.

[0084] The ends of the two feet 130a preferably have lugs, similar to the lugs 2 shown in [Fig. 2], which engage in the tube and bear against the inner wall of the tube, and shoulders, similar to the shoulders 2' shown in [Fig. 2], adapted to rest on the open end of the tube. The 130a feet can be rectangular in shape, and can include lights that can facilitate their placement on the tube and / or lighten the fixing device.

[0085] The fixing feet may also be of different numbers or have other shapes and specifications as described later in relation to figures 6 to 10.

[0086] At its end opposite the means of securing it to the movable element of the insert, e.g. the hook 110, the trunnion 120 has a head (14, 14', 141) capable of holding it captive from the bearing 130.

[0087] According to the invention, the head may be tubular with a rectangular longitudinal cross-section (i.e., along the Z-axis), like the head 14 shown in [Fig. 2], or it may comprise a semi-circular or circular longitudinal cross-section, as shown respectively in diagrams (3A) and (3B) of [Fig. 3], and preferably with a semi-circular or circular longitudinal cross-section, and even more preferably circular, the trunnion head then being a ball. The fact that the head comprises a semi-circular or circular longitudinal cross-section further reduces the friction between said trunnion head and said at least one low-friction wear-resistant part, it being understood that said semi-circular or circular longitudinal cross-section of the head is in contact with said at least one low-friction wear-resistant part.

[0088] According to the invention, the fastening device therefore comprises at least one low-friction anti-wear piece, disposed between the bearing 130, in particular the central part 130b of the bearing, and the head of the trunnion 120, and which has a longitudinal section of shape adapted to reduce friction between the low-friction anti-wear piece and the head of the trunnion and / or an additional anti-wear piece, said longitudinal section being circular, semi-circular, or frustoconical.

[0089] The fastening device may also include one or more additional wear-resistant parts, which may be positioned between said low-friction wear-resistant part and the central part 130b of the bearing 130 (not shown in [Fig. 3], but shown in Figures 4 and 5), in order to further limit wear on the other parts. This additional wear-resistant part(s) may be low-friction, i.e., having a circular, semi-circular, or frustoconical longitudinal cross-section that reduces friction between said additional low-friction wear-resistant part and the first low-friction wear-resistant part and / or another wear-resistant part.

[0090] During operation, when the moving element of the insert is rotated by the fluid flowing through the heat exchanger tube in which the insert is mounted, the head (14, 14', 141) integral with the journal 120 comes into contact either with the wear-resistant piece integral with the central part of the bearing (fixed part), or with an intermediate wear-resistant piece (disposed between the head and the central part of the bearing) if such a piece An intermediate wear-resistant element is provided, itself having a contact surface with the wear-resistant element attached to the central part of the bearing or with another intermediate wear-resistant element. Friction occurs primarily at the contact surface between, on the one hand, the moving part of the fastening device, i.e., the journal head, or an intermediate wear-resistant element if such a piece is provided (advantageously left free), and on the other hand, the fixed part of the fastening device, i.e., the wear-resistant element attached to the central part of the bearing. These wear-resistant elements therefore have the well-known function of limiting wear on the bearing head and the fixed bearing of the fastening device, in order to increase the robustness and service life of the fastening device.

[0091] Thanks to the use of at least one reduced friction anti-wear part as defined, the present invention makes it possible both to limit the wear of said parts and also to reduce the friction between the parts in contact with the reduced friction anti-wear part(s) of the fastening device, itself designated as the reduced friction fastening device, so as to facilitate the starting and more generally the rotation of the moving element of the insert in operation.

[0092] In figures 3 to 5, the reduced friction anti-wear part(s) are shown in grey to contrast with the trunnion head and / or additional anti-wear parts (which are not reduced friction).

[0093] The low-friction wear-resistant piece can be fixed, in contact with and integral to the central part 130b of the bearing 130, thus also acting as a stop to help maintain the trunnion rod 120 in the axis of rotation of the moving element of the insert and to stabilize it. In this case, the circular, semi-circular, or frustoconical longitudinal cross-sectional surface of said piece is in direct contact with the trunnion head, as shown, for example, in [Fig. 3]. The stop function to help maintain and stabilize the trunnion can also be provided by an additional wear-resistant piece (15, 150) in contact with and integral to said central part 130b, said additional wear-resistant piece being either low-friction or not, and being disposed between the first low-friction wear-resistant piece and the central part 130b of the bearing 130, as shown in Figures 4 and 5.

[0094] The reduced friction anti-wear part can be free, i.e., not attached to the moving part (trunk attached to the moving element of the insert) or to the fixed part formed by the bearing 130, as shown in figures 4 and 5 for the reduced friction anti-wear parts 160, 161, and 171.

[0095] Due to the specific longitudinal section, semi-circular, circular, or frustoconical, and preferably semi-circular or circular, the reduced-friction wear-resistant part(s) have a frictional contact surface that is minimized with the trunnion head, or with an additional wear-resistant part, or with the trunnion head. and an additional anti-wear piece when said low-friction anti-wear piece is disposed between the two.

[0096] According to the invention, the reduced friction anti-wear part(s) thus make it possible to reduce the threshold for starting rotation of the insert and a higher rotation speed of the insert at low flow rate.

[0097] Advantageously, the rotation threshold of an insert permitted by the low-friction fastening device according to the invention is less than Im / s, preferably between 0.1 m / s and 0.9 m / s. For example, the rotation threshold of the insert is between 0.5 m / s and 0.9 m / s.

[0098] The reduced friction anti-wear part, as well as the other additional reduced friction anti-wear parts, in particular left free, may be formed, or comprise a coating in a different material, for example a different alloy composition, from the rest of the parts of the fastening device, in particular different from the bearing and the trunnion head, and which has a low coefficient of friction.Thus, the low-friction wear-resistant part, as well as the other additional low-friction wear-resistant part(s), comprises a material with a coefficient of friction lower than that of the material forming the trunnion head and / or the central part of the mounting support (including the fixed wear-resistant part integral with the bearing), preferably comprises, or is made up of, at least one of the following materials, alone or in mixture: phosphor bronze, preferably in association with stainless steel, titanium, Hastelloy®, or Inconel®, more preferably phosphor bronze in association with stainless steel or titanium, or brass.

[0099] The fixed anti-wear part (15, 150), with reduced friction or not, which is integral with the bearing, may comprise, or even be made up of, at least one of the following materials, alone or in mixture: a steel with treatment (galvanized or other), a drawn steel, a stainless steel, such as 303, 316L, or 304 stainless steel, a metal alloy such as Hastelloy® or Inconel® alloy.

[0100] The reduced friction anti-wear part, in particular free, can be a ball, preferably with a diameter equal to the largest dimension of the cross-section (along an axis orthogonal to the Z axis) of the head of the journal and / or of said additional anti-wear part. However, the diameter of the ball can alternatively be greater or less than the largest dimension of the cross section (along an axis orthogonal to the Z axis) of the head of the trunnion and / or of said additional anti-wear part. Preferably, the low-friction wear-resistant part is a ball with a diameter less than or equal to, and preferably less than, the largest dimension of the cross-section transverse (along an axis orthogonal to the Z axis) of the head of the trunnion and / or of said additional anti-wear part, preferably of the head of the trunnion. For example, the ball has a diameter between 4.5 mm and 10 mm, preferably between 6 mm and 8 mm.

[0101] Fig. 3 illustrates in particular an embodiment of the reduced friction fastening device according to the invention, comprising a single anti-wear part 150 which is of reduced friction.

[0102] In example (3A) shown in [Fig. 3], the reduced friction fastening device 100 therefore comprises a single reduced friction wear-resistant piece 150 which is in contact with and fixed rigidly to the central part 130b of the bearing 130, making it a fixed part, and said single reduced friction wear-resistant piece 150 has a semi-circular or frustoconical longitudinal section, preferably semi-circular as shown, in contact with the head 14' of the journal 120 so as to reduce the friction between said head 14' and said single wear-resistant piece 150. In addition, the head 14' of the journal 120 preferably has a semi-circular longitudinal section in contact with the semi-circular or frustoconical longitudinal section of the reduced friction wear-resistant piece 150 so as to further reduce the friction between said journal head 14' and said reduced friction wear-resistant piece 150.

[0103] The bearing 130 of the fixing device 100 has two fixing feet 130a mounted on the central part 130b of the bearing 130 and forms a bracket whose end composed of the two feet allows the fixing of the movable element of the insert to the conduit of the heat exchanger tube.

[0104] According to this embodiment, the bearing 130 may be identical to that described in relation to [Fig. 2], which represents a fastening device known in the prior art. The bearing 130 may also be different from the bearing 13 illustrated in [Fig. 2], and may, for example, conform to the bearings of the embodiments shown in Figures 6 to 10.

[0105] In example (3B) shown in [Fig.3], the low friction fastening device 101 is identical to that of diagram (3A), except for the head 141 of the trunnion 120 which is a ball (circular longitudinal section).

[0106] Figure 4 illustrates an embodiment of the reduced friction fastening device according to the invention, comprising two anti-wear parts, at least one of which is reduced friction.

[0107] In example (4A) shown in [Fig.4], the reduced friction fastening device 102 comprises a single reduced friction anti-wear piece 160 and an additional anti-wear piece 15 disposed between said single reduced friction anti-wear piece 160 and the central part 130b of the bearing 130.

[0108] The anti-wear part 15, preferably tubular in shape, for example cylindrical, is fixed securely to the central part 130b of the bearing 130, making it a fixed part.

[0109] The single low-friction anti-wear piece 160 has a semi-circular or frustoconical longitudinal cross-section, preferably semi-circular as shown, in contact with the fixed additional anti-wear piece 15. The single low-friction anti-wear piece 160 is free.

[0110] The head 14' of the trunnion 120 may be tubular in shape as shown, for example cylindrical, but may also have a semi-circular or circular longitudinal section in contact with the single reduced friction anti-wear piece 160 so as to reduce the friction between said head and the single reduced friction anti-wear piece 160.

[0111] The bearing 130 of the fastening device 102 is identical to that described for the fastening device 100 of [Fig.3], and its description is not repeated here.

[0112] In example (4B) shown in [Fig.4], the reduced friction fastening device 103 is in all respects similar to that of the diagram (4A), except for the single reduced friction anti-wear part 161 which is a ball (circular longitudinal section), allowing further reduction of friction due to the reduction of the contact area in friction both between the head 14 of the trunnion 120 and said reduced friction anti-wear part 161, and between said reduced friction anti-wear part 161 and the fixed anti-wear part 15.

[0113] In example (4C) shown in [Fig. 4], the low-friction fastening device 104 is in all respects similar to that of diagram (4B), except that the fastening device comprises not a single low-friction wear-resistant part, but two low-friction wear-resistant parts consisting of the first low-friction wear-resistant part 161, which is a ball (circular longitudinal section) as in the fastening device 103 of diagram (4B), and the additional fixed low-friction wear-resistant part 150, in particular having a semi-circular longitudinal section in contact with said ball 161. This configuration makes it possible to reduce friction even further compared with the configuration of diagram (4B), due to the reduction of the contact area in friction between said ball 161 and the fixed low-friction wear-resistant part 150.According to this configuration, even if the ball 161 flattens over time due to wear during the operation of the insert, the contact surface between said ball 161 and the fixed low-friction anti-wear part 150 remains smaller thanks to the semi-circular longitudinal section of said part 150 in contact with the ball.

[0114] Figure 5 illustrates an embodiment of the reduced friction fastening device according to the invention, comprising three anti-wear parts which are of reduced friction.

[0115] The low-friction fastening device 105 illustrated in [Fig. 5] includes a first low-friction anti-wear part 161, which is a ball, in contact with the head 14 of the trunnion 120. The fastening device 105 also includes two other additional low-friction anti-wear parts, in particular a ball 171 in contact with the ball 161, and preferably similar to it, and an additional fixed low-friction anti-wear part 150 fixed to the central part 130b of the bearing 130, and having a semi-circular longitudinal section in contact with the ball 171. The balls 161 and 171 are free.

[0116] This configuration makes it possible to increase the wear resistance of the low-friction fastening device.

[0117] The head 14 of the trunnion 120 can be tubular in shape as shown, for example cylindrical, but can also have a semi-circular or circular longitudinal section in contact with the ball 161 so as to reduce friction between said head and the ball 161.

[0118] The bearing 130 of the fastening device 105 is identical to that described for the fastening device 100 of [Fig.3], and its description is not repeated here.

[0119] The various embodiments described above in relation to Figures 3 to 5 make it possible, in particular, to lower the rotation threshold of an insert incorporating such a low-friction fastening device, improving the flexibility of use of such inserts, especially at low fluid flow velocities in the tube, typically at flow velocities below 1 m / s. They also allow for greater stability of the insert, in particular greater operational stability due to reduced wear, thanks to the low-friction wear-resistant parts of the fastening device generating less friction and less wear related to said friction compared to the prior art. Thus, the robustness of the low-friction fastening device, and consequently also of the insert fixed to the tube by such a fastening device, is improved, with a minimized risk of breakage, and they therefore offer a longer service life.

[0120] According to the invention, the low-friction fastening device may comprise two fastening feet as described above in relation to Figures 3 to 5, but it may alternatively comprise other configurations of fastening feet, making it possible to increase the stability and / or robustness of said fastening device, while optimizing, in particular limiting, the size of the fastening device in order to limit pressure loss as well as potential fouling due to particles that may be deposited on the feet during the operation of the insert, when a fluid flows towards the tube and is in contact with said fastening device. With regard to stability, it is the mechanical stability of the low-friction fastening device and the insert incorporating it that can be increased by means of configurations of specific feet described below, but also the operating stability of the insert because particular foot configurations can reduce vibrations of the insert during operation, which is often a source of premature wear of the insert fixing device.

[0121] Advantageously, the fastening device according to the invention comprises fastening feet having a minimal footprint, and in particular a volume formed by all the feet that is minimal so as to limit pressure loss, as well as fouling of the device by the deposition of solid particles on said feet during the circulation of a potentially fouling fluid. Said volume formed by all the feet depends, for example, on the number of feet, their thickness, their shape, etc.

[0122] Figures 6 to 10 illustrate such specific foot configurations.

[0123] In the examples of embodiments of the fastening device according to the invention illustrated in Figures 6 to 10, the fastening device comprises a configuration of the wear-resistant parts similar to the low-friction fastening device 103 illustrated in diagram (4B) of [Fig. 4], without this being a limitation of the invention. Indeed, all the configurations of the wear-resistant parts described in relation to Figures 3 to 5 can be combined with the foot configurations described in relation to Figures 6 to 10.

[0124] Figure 6 illustrates an embodiment of the low-friction fastening device according to the invention, comprising four fixing feet.

[0125] The reduced friction fastening device 106 illustrated in [Fig.6] is similar in every respect to the reduced friction fastening device 103 illustrated in diagram (4B) of [Fig.4] with regard to the anti-wear parts, comprising as a reminder a single reduced friction anti-wear part 161 which is a ball in contact with the head 14 of the trunnion 120 and an additional fixed anti-wear part 15, which is not of reduced friction (tubular shape, for example cylindrical).

[0126] The head 14 of the trunnion 120 can be tubular in shape as shown, for example cylindrical, but can also have a semi-circular or circular longitudinal section in contact with the ball 161 so as to reduce friction between said head and the ball 161.

[0127] The material or materials forming the trunnion, as well as the head of the trunnion, are those described above in relation to figures 3 to 5.

[0128] The bearing 131 of the fastening device 106 has a central part 131b comprising the opening preferably centered on the Z axis, for retaining the trunnion 120, and differs in particular from the bearing 130 of the fastening device 103 of [Fig.4] in that it has four feet 131a, instead of two feet for the fastening device 103 of [Fig.4], formed of a rigid material capable of deforming elastically and to be forcibly engaged at an open end of the tube to bear elastically against an internal wall of the tube, allowing attachment to the tube conduit (tube not shown). Said four feet 131a are mounted on the central part 131b of the bearing 131 and form a double bracket, the end of which, composed of the four feet, allows the movable element of the insert to be attached to the tube conduit of the heat exchanger. Each foot advantageously has, at its end opposite the central part 131b of the bearing 131, a lug adapted to be engaged in the open end of the tube against an internal wall of said tube, and a shoulder extending on either side of the lug adapted to rest on the open end of the tube, as already described for the feet of the fastening device 103 of [Fig. 4].

[0129] The material or materials forming the bearing 131 are those described above for the bearing 130 in relation to figures 3 to 5.

[0130] The feet 131a may be substantially rectangular in shape and may include slots to facilitate their placement on the tube and / or lighten the fastening device, for example, circular or rectangular slots extending from one end of the foot to the other as illustrated in [Fig. 2], or may have an inverted structure of said rectangular slots with feet each having a substantially rectangular central portion whose width is less than the distance formed between the two ends of the shoulder of the end of said foot, in order to lighten said foot (not shown). The connection of the rectangular central portion of the foot to the ends of the foot, on the side of the central piece 131b of the bearing and / or on the tube side, may be gradual and include a curve, or may form an angle, without a smooth transition.

[0131] According to this embodiment, the reduced friction fastening device, and the insert which includes it, has improved stability.

[0132] Figure 7 illustrates an embodiment of the low-friction fastening device according to the invention, comprising three fixing feet with rounded ends.

[0133] Diagram (7A) is a 3D side view of the fastening device 107, and the diagram (7B) is a view from below of said device for a better illustration of the geometry of the rounded ends of the feet.

[0134] The low-friction fastening device 107 includes a bearing 132 comprising a central part 132b having an opening, preferably centered on the Z axis, for retaining the trunnion 120, and three feet 132a mounted on said central part 132b. Each foot 132a has a rounded end 132c as detailed below.

[0135] The low-friction fastening device 107 illustrated in [Fig. 7] is in all respects similar to the low-friction fastening device 106 of [Fig. 6], except that it has three feet, and each foot has one end, the one on the tube side, which is rounded; more specifically, the end of each foot has a A lug 132d surmounted by a shoulder 132e, the lug and the shoulder having an external surface curved in the shape of a circular arc adapted to follow the curvature of the inner wall of the heat exchanger tube. The shoulder preferably has a thickness (dimension in a plane orthogonal to the Z-axis along the direction given by a diameter of the circle formed by the external walls of the shoulders) greater than the lug, so as to be able to rest on the open end of the tube.

[0136] According to this embodiment, the contact surface between the tube and the end of the foot is larger, and consequently the stability of the reduced friction fastening device 108, and the insert which includes it, is improved.

[0137] Figure 8 illustrates an embodiment of the low-friction fastening device according to the invention, comprising four fixing feet with rounded ends.

[0138] The low-friction fastening device 108 comprises a bearing 133 including a central part 133b having an opening, preferably centered on the Z axis, for retaining the trunnion 120, and four feet 133a mounted on said central part 133b. Each foot 133a has a rounded end 133c as detailed in [Fig. 7],

[0139] The low-friction fastening device 108 illustrated in [Fig.8] is identical in every respect to the low-friction fastening device 107 of [Fig.7], except that it has four feet instead of three.

[0140] According to this embodiment, the reduced friction fastening device 108, and the insert which includes it, has even improved stability, compared to the embodiment of [Fig.7].

[0141] Figure 9 illustrates an embodiment of the low-friction fastening device according to the invention, comprising two fixing feet with rounded ends and an enlarged shoulder.

[0142] Diagram (9A) is a three-quarter view of the fastening device 109, and the diagram (9B) is a view from below of said device for a better illustration of the geometry of the rounded ends with enlarged shoulder of the feet.

[0143] The low-friction fastening device 109 includes a bearing 134 comprising a central part 134b having an opening, preferably centered on the Z axis, for retaining the trunnion 120, and two feet 134a mounted on said central part 134b. Each foot 134a has a rounded end 134c with an enlarged shoulder as detailed below.

[0144] The low-friction fastening device 109 illustrated in [Fig. 9] is similar to the low-friction fastening device 107 of [Fig. 7], except that it has two feet 134a, and that each foot has a rounded end 134c, the end on the tube side, and more particularly the end of each foot has a lug 134d surmounted by a shoulder 134e, the lug and the shoulder having a surface The external curved arc is adapted to follow the curvature of the inner wall of the heat exchanger tube, and the shoulder 134e forms a circular arc with a larger opening than the circular arc formed by the lug 134d. For example, the opening of the circular arc is approximately three times larger for the shoulder than for the lug. For example, the surface area of ​​the shoulder covers one-quarter of the circumference of the inner wall of the tube.

[0145] According to this embodiment, the contact surface between the tube and the end of the foot is larger, in particular that between the shoulder and the open end of the tube, which improves the stability of the low-friction fastening device 109, and the insert which includes it.

[0146] Fig. 10 illustrates an embodiment of the low-friction fastening device according to the invention, comprising two fastening feet with ends having lugs with rounded tips.

[0147] Diagram (10A) is a three-quarter view of the fastening device 110, and diagram (10B) is a view from below said device for a better illustration of the geometry of the ends with lugs with rounded tips.

[0148] The low-friction fastening device 110 comprises a bearing 135 including a central part 135b having an opening, preferably centered on the Z axis, for retaining the trunnion 120, and two feet 135a mounted on said central part 135b. Each foot 135a has an end 135c having lugs with rounded tips as detailed below.

[0149] The low-friction fastening device 110 illustrated in [Fig. 10] is similar to the low-friction fastening device 109 of [Fig. 9], except that each of the two feet 135a has an end 135c, the tube-side end, having a lug 135d surmounted by a shoulder 135e, said lug 135d being provided with an end piece 135f, on the tube side, having a curved external surface in the form of an arc adapted to follow the curvature of the inner wall of the heat exchanger tube. More specifically, the lug 135d is rectangular in shape, elongated along the Z-axis, substantially flat, and in line with the foot 135a and the shoulder 135e, and terminates in a wider end piece 135f forming an arc adapted to follow the curvature of the inner wall of the tube. For example, the surface of the nozzle covers a quarter of the circumference of the inner wall of the tube.The shoulder 135e above the lug 135d is flat, for example generally trapezoidal in shape, and may be provided with a central circular opening to facilitate its placement of the fixing device on the tube. The bearing 135 is also slightly different from the bearing 134 in [Fig. 9], notably in that the central part 135b is rectangular instead of cylindrical, and in that the feet 135a each have a substantially rectangular central part of . width less than the distance formed between the two ends of the shoulder 135th of the end of the foot.

[0150] According to this embodiment, the contact surface between the tube and the end of the foot is larger, in particular that between the lug and the open end of the tube, which improves the stability of the low-friction fastening device 110, and the insert which includes it.

[0151] The present invention also relates to a rotating insert for a heat exchanger tube incorporating a low-friction fastening device as described above.

[0152] According to the invention, the heat exchanger tube insert comprises a rotating moving element, said rotating moving element being able to comprise a metal rod, a twisted band, a central shaft with blades, or any other known rotating moving element of heat exchanger inserts.

[0153] Preferably, the moving element comprises a rigid helical winding of a rod, typically metallic, comprising several turns, said moving element being connected to the low-friction fastening device for its attachment to the heat exchanger tube. Such a rigid helical winding thus has a spring-like shape, and is often referred to as such (spring).

[0154] The rigid helical winding may have different characteristics, and may for example have a fixed or variable pitch, and in particular include an initial portion with a tighter pitch as illustrated in [Fig.1 1] helping to rotate the insert.

[0155] The moving element of the insert may also include a rotating drive part positioned between the fixing device and the main moving part of the rotating element, formed, for example, by the rigid helical winding, also intended to reduce the rotation threshold of the insert during operation. Such an example of a rotating drive part, operating solely under the action of the fluid passing through the heat exchanger, is illustrated in [Fig. 1 1].

[0156] Figure 11 illustrates one embodiment, in particular an example of an insert incorporating a fastening device according to the invention, for example, and without limitation, a fastening device 107 as illustrated in Figure 7, and in which the movable element 200 of said insert comprises a rigid helical winding 20, preferably metallic, having several turns. The movable element further comprises a rotating drive piece 30 connected to the rigid helical winding.

[0157] The low-friction fastening device 107 is that illustrated in [Fig.7], although the other low-friction fastening devices described in relation to Figures 3 to 10 can be used in the insert according to this embodiment.

[0158] According to this embodiment, the insert comprises a fastening device according to any one of the embodiments described above, and a rotating movable element 200 comprising a rigid helical winding of a rod, preferably metallic, comprising several turns 20, said rotating mobile element 200 comprising: - a first end fixed to the trunnion 120 of the fixing device allowing the free rotation of said rotating mobile element 200 on itself around the axis Z of the tube 1, substantially coinciding with the axis of extension of the trunnion rod, under the action of a fluid passing through said tube 1, and - a second free end.

[0159] Although, according to the invention, the first end of the moving element which is integral with the trunnion can be formed by an end of the rigid helical winding 20, for example in the form of a ring or any other suitable shape, this first end of the moving element can also be that (3c) of a rotating drive part 30 such as in the example shown in [Fig. 11].

[0160] The rotating movable element 200 thus comprises a first end 3c, on the side of the rotating drive piece, fixed to the rod of the trunnion 120 of the fastening device 107 of the element 200 to the tube 1 of the heat exchanger, the trunnion 120 allowing the free rotation of the element 200 about itself around the axis Z of said tube 1 under the action of a fluid flowing through the tube (cylindrical tube with axis Z). The second end of the rotating movable element 200, on the side of the rigid helical winding, and opposite the first end 3c, is left free.

[0161] The rigid helical winding may be known from the prior art and as described in relation to [Fig. 1]. The rigid helical metal winding comprises a plurality of turns of length L, diameter D, pitch p, and angle of inclination alpha (a) defined with respect to the central axis of the winding coinciding with the axis Z of the heat exchanger tube in which the insert is mounted, the metal rod forming the winding having a thickness e. The pitch can be defined generally as a function of the angle of inclination of the turns a and the diameter of the turns of the rigid helical winding D, according to the following relation: pitch = (ji D) / tana. The metal winding has a free end and an end, for example, fitted with a ring to be connected, directly or indirectly (for example via the rotating drive part), to the tube fixing device. Preferably, the pitch p of the turns of the rigid helical winding 20 is between 10 mm and 60 mm, preferably between 20 mm and 45 mm.

[0162] The diameter D of the rigid helical winding 20 corresponds to the diameter of the turns. D is greater than or equal to 80%, preferably 90%, of the diameter Dt of the heat exchanger tube 1, in order to generate optimal turbulence in the circulating fluid and to scrape deposits from the tube wall efficiently. D is, for example, between 80% and 99% of Dt, preferably between 85% and 95% of Dt. Advantageously, there is a gap "c" between the rigid helical winding 20 and the inner wall of the tube 1 such that the rigid helical winding of the moving element does not touch the tube wall, so as not to damage the tube wall, for example, by creating scratches that could form surface irregularities that could promote corrosion. This gap "c" is preferably between 1 mm and 3 mm.

[0163] The diameter of the tubes Dt (internal diameter) can be between 10 mm and 100 mm, preferably between 10 mm and 50 mm.

[0164] The stem of the rigid helical winding 20 may have a circular or square (cross-section) or some other shape, and more preferably has a circular cross-section. The thickness of the stem (diameter in the case of a stem with a circular cross-section) is preferably between 0.5 mm and 5 mm, more preferably between 1 mm and 3 mm. The winding direction, which can also be defined as the direction of the coil pitch, can be clockwise or counterclockwise (relative to the direction of fluid flow in the tube, represented by an arrow along the Z-axis in the figures). The direction of the rigid helical winding 20 is the same as the direction of winding of the blades 30b around the shaft 3a of the rotating drive part 30.

[0165] The rotating moving element 200 comprises the rotating drive piece 30 which is disposed between the fixing device 107 and the rigid helical winding 20, and which is connected in a rotationally fixed manner with said rigid helical winding and said trunnion 120 of the fixing device 107, the rotating drive piece 30 comprising a shaft 3a coaxial with said rigid helical winding and said shaft 3 is provided with at least two blades 30b fixed to said shaft.

[0166] Preferably, the rotating drive part 30 comprises two to six blades, and more preferably three to five blades, for example four blades as illustrated in [Fig. 11], preferably all identical (i.e. having the same geometric characteristics such as length, diameter, thickness, etc.).

[0167] The rotating drive part 30 is for example screw-shaped, as illustrated, although other configurations can be adapted to assist in rotating the rigid helical winding 20. The screw-shaped rotating drive part 30 has blades forming spirals, and the pitch of each blade p3 (pitch of revolution) is preferably between 10 mm and 50 mm, more preferably between 15 mm and 20 mm. The blades wind around the shaft 3a along the entire length of the part, giving the part its screw shape. The pitch of revolution of the blades is advantageously adjusted so as to generate the moment necessary to start the rotation of the insert while respecting the pressure loss constraint. The blades form spirals with preferably an angle of inclination which is constant along Z, and which varies with the radius r according to the equation: [33=arctan((2ir * r) / p3), the pitch p3 being constant. Preferably, the number of turns (also called revolutions) for the screw-shaped drive part is greater than 1, for example equal to 5 as illustrated in [Fig. II].

[0168] According to this embodiment, the rotating drive part 30 has a length which preferably corresponds substantially to the length L3 of a blade, and is more preferably between 10 mm and 500 mm, preferably between 20 mm and 200 mm.

[0169] The blades 30b have a diameter dr3, preferably greater than or equal to 80% or 90% of the diameter Dt of the heat exchanger tube 1, for example, between 80% and 99% of the diameter Dt. Advantageously, there is a gap between the rotating drive part 30, more precisely the tip of the blades 30b, and the inner wall of the tube 1, for example, between 1 mm and 3 mm, so that the blades do not touch the tube wall, thus preventing damage to the tube wall. The diameter dr3 may be equal to or different from the diameter D of the rigid helical winding 20. Preferably, the diameter dr3 of the 30b blades is between 8 mm and 99 mm, preferably between 8.5 mm and 95 mm, more preferably between 8.5 mm and 50 mm, and even more preferably between 10 mm and 25 mm. The diameter of a blade is constant or may vary in the direction of the shaft axis.

[0170] The blades 30b have a thickness e3, preferably between 0.3 mm and 5 mm, preferably between 0.3 mm and 3 mm, more preferably between 1 mm and 3 mm. The thickness of the blades must be minimal while still meeting mechanical constraints, in order to reduce the overall size and thus the pressure loss.

[0171] The shaft 3a of the rotating drive part 30 has a diameter da3, preferably between 1 mm and approximately 50% of Dt, typically between 1 mm and 50 mm, preferably between 2 mm and 10 mm. The diameter of the shaft 3a influences the fluid passage area, and large values ​​of the diameter da3 allow for an increase in fluid velocity, locally at the rotor. The diameter da3 of the shaft 3a is preferably constant along the Z-axis, although it may vary.

[0172] The rotating drive piece 30 can be connected to the rigid helical winding 20 by any fastening means allowing the joint rotation of said rigid helical winding 20 with the drive piece 30, and therefore ultimately of the moving element 200, about itself around the Z-axis under the action of a fluid flowing through the tube 1. For example, the rotating drive part 30 has an end 3d, opposite end 3c, which has a hook connected to a ring carried by the end la of the rigid helical winding 20. The other end of the rigid helical winding 20, which is also that of the rotating moving element 200 of the insert, is left free. Any suitable fastening means other than a hook-washer assembly can be used to secure the part 30 and the winding 20.

[0173] The shaft 3a and the blades can be a single unit (i.e. manufactured in one piece), or alternatively be separate units fixed to each other for example by welding or any other rigid fastening means allowing the whole to be joined together.

[0174] The material forming the rotating drive part and the rigid helical winding, preferably metallic, may be carbon steel, stainless steel, or any other metal or metal alloy material such as Inconel®, providing the insert with the required rigidity and preferably resistant to high temperatures and corrosion. The insert material is preferably less hard than the heat exchanger tube duct material to prevent degradation of said tube. For highly corrosive fluids, the material forming the insert can be coated with a layer of protective material, typically a polymer layer. The material forming the moving element of the insert can also be a polymer or composite material (metal or metal alloy with a polymer material, or different types of polymers, or a composite material combining different types of reinforcements, such as fibers, particles, etc., with different matrices, such as a polymer, metallic or ceramic matrix). The rigid helical winding 20 and the rotating drive part 30 are robust components, i.e., their risk of breakage is low. The material used for each of these parts may be the same or different.

[0175] The total length of the moving element 200 of the insert is essentially equal to the sum of L3 and L, respectively the length of the rotating drive part 30 and that of the rigid helical winding 20.

[0176] The total length of the moving element 200 is less than or equal to the total length of the tube 1 Lt of the heat exchanger, and preferably between 50% and 100% of Lt. The diameter (Lt) can be between 500 mm and 15,000 mm, preferably between 1,000 mm and 6,000 mm. For example, heat exchangers commonly used in oil refining, for instance, in oil preheating. Crude oil in atmospheric distillation can include heat exchanger tubes ranging from 1 meter to 6 meters in length. In the nuclear field, heat exchangers in nuclear power plant condensers can have tubes up to 14 meters long. Advantageously, the length L of the rigid helical winding 20 is between 400 mm and 14000 mm. For example, if the total length of the moving element of the insert is equal to that of the tube and is 6,000 mm, the length L of the rigid helical winding 20 is approximately between 5,500 mm and 5,990 mm, and preferably approximately between 5,800 mm and 5,950 mm.

[0177] Advantageously, when the insert according to the invention is used in a heat exchanger tube, the moving element is rotated by the circulating fluid. This increases the turbulence of the circulating fluid, improves heat exchange, and homogenizes the temperature of the circulating fluid over the entire cross-section of the tube. This prevents the formation of hot spots on the tube wall and consequently significantly reduces the risk of solid deposit formation and improves heat transfer, which is typically hampered by this type of deposit. The rotating insert also scrapes away any deposits that may have formed on the wall, thus reducing fouling. In addition to reducing deposits, heat transfer is improved due to the increased turbulence of the circulating fluid caused by the rotation of the insert, which enhances convective heat transfer.Indeed, the mere presence of the insert, and even more so its rotation, creates turbulence which leads to increased heat transfer by reducing the thickness of the heat transfer boundary layer and thus the transfer resistance near the wall. The heat transfer performance of tubular heat exchangers incorporating such inserts is therefore improved, as is the lifespan of the heat exchangers.

[0178] The rotation threshold of an insert corresponds to the minimum surface velocity of the circulating fluid allowing the rotation of the moving element of the insert. The moving element, rotating in the opposite direction to the helical winding of the spring, with a speed that depends on its weight, its geometric characteristics, the flow rate, the viscosity and the density of the circulating fluid, therefore has its own rotation threshold.

[0179] In the context of the present invention, the insert according to the invention has the capacity to have a lower rotation threshold compared to existing rigid helical-wound inserts. This lower rotation threshold is linked to the low-friction fastening device and can be further reduced by integrating a specific drive piece positioned upstream and connected to the rigid helical winding of a rod. as described here, which is an aid to the rotation of the rigid helical winding. The rotation threshold of the insert is reduced, thus ensuring a mechanical effect in low flow velocity ranges (typically less than 1 m / s) of the fluid in the heat exchanger tube, which improves the flexibility of use of this type of insert.

[0180] Advantageously, the rotation threshold of an insert according to the invention is less than Im / s, preferably between 0.1 m / s and 0.9 m / s. For example, the rotation threshold of an insert according to the invention is between 0.5 m / s and 0.9 m / s.

[0181] Fig. 12 illustrates another embodiment, in particular an example of an insert in which the moving element 201 includes a rotating drive piece 30 as described in relation to the insert illustrated in Fig. 11, said drive piece being connected to a rigid helical winding of a rod 21 (preferably metallic) comprising several turns which is specific: it includes an initial portion with a tight pitch. The said specific rigid helical winding 21 is in fact made up of a first portion SI of length L1 and a second portion S2 of length L2 in the extension of the first portion SI, the first pitch pl of the turns of the first portion SI being smaller (strictly less) than the second pitch p2 of the turns of the second portion S2. The presence of an initial portion with a tighter pitch compared to the rest of the winding of the moving element 201 of the insert, in particular according to the specifications described below, makes it possible to further reduce the threshold for starting rotation of the insert, which further improves the flexibility of use of this type of insert.

[0182] Preferably, the pitch pl is between 5 mm and 20 mm, preferably between 5 mm and 15 mm, and more preferably between 7 mm and 12 mm. Preferably, the p2 pitch is between 10 mm and 60 mm, and preferably between 20 mm and 40 mm.

[0183] Advantageously, the ratio between the step pl and the step p2 is between 0.1 and 0.7, preferably between 0.20 and 0.45.

[0184] Reference is made to the angle of inclination of the turns ai for the angle of inclination of the turns of the first portion, and to the angle a2 for the angle of inclination of the turns of the second portion.

[0185] The rigid helical winding has a diameter D, which corresponds to the diameter of the turns of the winding, and which is common to the first and second portions S1 and S2. D is preferably greater than or equal to 80%, preferably 90%, of the diameter Dt of the tube 1 of the heat exchanger. D is, for example, between 80% and 99% of Dt, preferably between 85% and 95% of Dt. Advantageously, there is a space "c" between the rigid helical winding 21 and the inner wall of the tube 1, preferably between 1 mm and 3 mm.

[0186] The stem of the rigid helical winding 21 may have a circular or square or other shape (cross-section), and more preferably has a circular cross-section. The rod, preferably metallic, forming the rigid helical winding 21 has a diameter e1 at the level of the first portion SI, and has a diameter e2 at the level of the second portion S2. The diameters el and e2 are preferably between 0.5 mm and 5 mm, and more preferably between 1 mm and 3 mm. The diameters el and e2 may be the same or different. Having identical diameters el and e2 has the advantage of simplifying the manufacture of the insert.

[0187] The direction of the rigid helical winding 21 can be clockwise or counterclockwise (relative to the direction of fluid flow in the tube). Advantageously, it is the same as the direction of winding of the blades around the shaft 3a of the rotating drive part 30.

[0188] Advantageously, the length L1 of the first portion SI is between 100 mm and 3000 mm, preferably between 200 mm and 1000 mm.

[0189] The first portion SI and the second portion S2 are joined together, and can form a single piece or be two separate pieces connected so as to be joined together by means of assembly such as a hook-washer assembly or any other means of assembly.

[0190] The total length of the moving element 201 is essentially equal to the sum of L3 (length of the rotating drive part 30), L1 and L2.

[0191] The length L2 of the second portion S2 can therefore be defined as the total length of the moving element 201, related to Lt (length of the exchanger tube), from which it is subtracted (L3 + Ll). For example, if the total length of the moving element 201 of the insert is equal to that of the tube and is 6,000 mm, the length L2 is approximately between 2,500 mm and 5,890 mm, and preferably between 4,800 mm and 5,750 mm.

[0192] It is understood that such a rigid helical winding 21 of initial portion with a tight pitch can be combined with another rotating drive part 30 than that exemplified in [Fig. 12].

[0193] The present invention also relates to a heat exchanger comprising a plurality of tubes 1 through which a fluid flows, comprising an insert integrating a low-friction fastening device according to the invention, in particular fixed to the upstream end of at least one of these tubes.

[0194] The heat exchanger according to the invention is advantageously a shell and tube heat exchanger as defined above.

[0195] The heat exchanger can be single-phase or two-phase, that is, the fluid on the tube side can comprise a single phase, for example liquid, or two phases, typically liquid and gas. Preferably, the heat exchanger comprising at least one insert according to the invention is single-phase.

[0196] The length of the tubes can be between 500 mm and 15,000 mm, preferably between 1,000 mm and 6,000 mm.

[0197] The diameter of the tubes (internal diameter Dt) can be between 5 mm and 100 mm, preferably between 10 mm and 80 mm, preferably between 10 mm and 50 mm.

[0198] The heat exchanger preferably comprises a plurality of horizontal tubes (the axis of the tubes being horizontal). In this case, the insert is itself horizontal in the operating position. The invention also includes heat exchangers with vertical tubes. In this case, the insert is itself vertical in the operating position.

[0199] The present invention also relates to the use of an insert for a tubular heat exchanger.

[0200] In particular, the present invention relates to the use of such an insert during the preheating of crude oil in an atmospheric distillation process of crude oil. In the field of oil refining, it is common to carry out atmospheric distillation of crude oil which is preheated, before being sent to the distillation column, in tubes of one or more heat exchangers in contact with the hot atmospheric residue from atmospheric distillation. The present invention relates to the use of an insert for a tubular heat exchanger according to the invention during the preheating of crude oil, in particular an atmospheric distillation process employing one or more heat exchangers comprising a plurality of tubes through which crude oil flows, said exchanger(s) being equipped with at least one insert according to the invention, in particular fixed to the upstream end of at least one of said tubes. The use of such an insert in this context notably provides operational flexibility at both low and high flow rates, which can be linked to a transient or steady-state regime.

[0201] The heat exchanger inserts according to the invention can be used in other industrial processes employing tubular heat exchangers and fluids, including but not limited to fluids that may foul said exchangers, particularly in the field of oil refining or petrochemicals, without departing from the scope of the present invention.

[0202] The present invention thus relates, for example, to the use of a tubular heat exchanger insert as described herein in a hydrotreating or hydroconversion process for hydrocarbon feedstocks, in particular petroleum fractions, typically for preheating such a feedstock by means of so-called "charge-effluent" exchangers incorporating at least one insert according to the invention, in which the charge is heated by an effluent from the hydrotreatment or hydroconversion unit.

[0203] The present invention also relates to the use of a tubular heat exchanger insert as described herein for the evaporation or condensation of a fluid in a nuclear power plant. The heat exchangers are then of the evaporator or condenser type, such as reboilers in distillation columns or condensers in nuclear power plants. Examples

[0204] The examples below are based on the implementation of a so-called "cold" experimental model, and are intended to show some of the advantages of the heat exchanger insert and its use according to the invention.

[0205] The cold model includes a transparent PVC heat exchanger tube 3 m long and 21 mm in diameter (internal diameter Dt), in which water at ambient temperature and pressure is circulated, over a surface velocity range in the tube between 0.2 and 2 m / s (flow rates between 0.2 and 2.5 m3 / h).

[0206] Two examples of inserts with a fixing device are tested: - Example A: Example of an insert according to the prior art, as illustrated in [Fig.1] comprising a movable element comprising a rigid helical winding of fixed pitch p of 35 mm, of 3 meters in length, and of coil diameter of 18.7 mm, attached to a fixing device according to the prior art as illustrated in [Fig.2]. - Example B: Example of an insert comprising a low-friction fastening device according to the invention, in particular according to the embodiment illustrated in [Fig. 4] diagram (4B), attached to a moving element comprising a rigid helical winding of fixed pitch p similar to the winding of Example A. The ball 161 has a diameter of 6 mm. The head of the trunnion 14, of cylindrical tubular shape, has a diameter of 8 mm, and the fixed anti-wear piece 15, of cylindrical tubular shape, has a diameter of 8 mm.

[0207] The rigid helical winding of the moving element of the inserts according to examples A and B is made of stainless steel and has a shank with a circular cross-section. The winding direction is clockwise relative to the position of the insert at the tube inlet.

[0208] The fastening device of examples A and B is made of stainless steel.

[0209] To evaluate the performance of the insert in each example, the evolution of the rotation speed of the insert in revolutions per minute (rpm) is plotted as a function of the surface velocity of the liquid in the tube normalized by the minimum velocity of the liquid for rotating the insert according to example A taken as a reference.

[0210] The diagram in [Fig. 13] thus shows the rotation speed VR (RPM or rpm) of the insert according to example A (non-compliant) and according to example B (compliant with the invention), as a function of the normalized liquid speed VSL: VSL / VSL_ref, VSL_ref being the minimum liquid speed for starting rotation of the insert according to example A.

[0211] According to the diagram in [Fig. 13], the relative rotation speed of the insert according to Example A is 1.0, while that of an insert according to Example B is less than 1.0, in particular less than 0.8, and in absolute terms less than 0.6 m / s. The results indicate that an insert according to the invention, as exemplified in Example B, reduces the rotation threshold of the insert by 21% (-21%), thus enabling better performance in reducing fouling at low fluid velocities, thanks to the rotational mechanical effect of the insert's moving element.

Claims

Demands

1. A fastening device for an insert (100 to 110) comprising a rotating movable element for a heat exchanger tube, said fastening device comprising: - a fastening support (130 to 135) forming a bearing for a trunnion (120), said fastening support comprising a central part (130b, 131b, 132b, 133b, 134b, 135b) provided with an opening and at least two fixing feet (130a, 131a, 132a, 133a, 134a, 135a) of a rigid material capable of elastic deformation, mounted on said central part and capable of being press-fitted into an open end of the tube to bear elastically against an internal wall of said tube, - said trunnion (120) comprising a rod elongated along an axis Z engaged in the opening of said central part and a head (14, 14', 141) at one end of said rod, said head being disposed on the side of said central part intended to be oriented towards the outside of the tube,the other end of said trunnion rod being capable of being made integral with the rotating movable element of the insert, - at least one low-friction wear-resistant part (150, 161) disposed between said central part and the trunnion head, characterized in that said low-friction wear-resistant part has a longitudinal section, along the Z-axis, of a shape adapted to reduce friction between said low-friction wear-resistant part and the trunnion head and / or an additional wear-resistant part, said longitudinal section being circular, semi-circular, or frustoconical.

2. Device according to claim 1, wherein the trunnion head (14', 141) comprises a semi-circular or circular longitudinal section in contact with the circular, semi-circular or frustoconical longitudinal section of said reduced friction wear piece (150) so as to reduce the friction between said trunnion head and said reduced friction wear piece (150).

3. Device according to claim 2, wherein the trunnion head is a ball.

4. A device according to any one of the preceding claims, comprising a single low-friction wear-resistant piece (150) in contact with and fixed securely to the central portion (130b) of the bearing (130), and said single low-friction wear-resistant piece has

5.

6.

7.

8.

9.

10.

11.

12. a semi-circular or truncated conical longitudinal section in contact with said trunnion head (14', 141) (120) so as to reduce friction between said trunnion head (14', 141) (120) and said single anti-wear piece (150). Device according to any one of claims 1 to 3, comprising at least one additional anti-wear part (15, 150, 171) disposed between said reduced friction anti-wear part (160, 161) and the central part (130b) of the bearing (130). Device according to claim 5, wherein said reduced friction anti-wear part (161) is a ball. Device according to claim 5 or 6, wherein said at least additional anti-wear part is of reduced friction (150, 171). Device according to any one of claims 5 to 7, comprising a low-friction wear-resistant part (161) forming a first ball in contact with the head (14) of the trunnion (120), and two additional wear-resistant parts (171, 150) which are low-friction, one of them forming a second ball in contact with the first ball. Device according to any one of claims 5 to 8, wherein said at least one reduced friction anti-wear part is a ball with a diameter less than the largest dimension of the cross-section of said trunnion head and / or of said additional anti-wear part. Device according to any one of the preceding claims, comprising three or four fixing feet, each foot having at its end opposite the central part of the bearing a lug surmounted by a shoulder, said lug and said shoulder having an external surface curved in an arc of a circle adapted to follow the curvature of the internal wall of the heat exchanger tube. Device according to any one of the preceding claims, comprising four fixing feet. A device according to any one of claims 1 to 9, comprising two mounting feet, each foot having at its end opposite the central part of the bearing a lug (134d, 135d) surmounted by a shoulder (134e, 135e), and wherein said lug (134d) and said shoulder (134e) have a curved external surface adapted to follow the curvature of the inner wall of the heat exchanger tube, and said shoulder (134e) forms an arc of a circle of more large opening than the arc of the circle formed by said lug (134d), or in which said lug (135d) is rectangular and surmounted by a flat shoulder (135e), said lug (135d) comprising an end piece (135f) having a curved external surface suitable for following the curvature of the internal wall of the heat exchanger tube.

13. Device according to any one of the preceding claims, wherein said at least one reduced friction wear-resistant part comprises a material with a coefficient of friction lower than that of the material forming the trunnion head and / or the central part of the fixing support, preferably phosphor bronze, preferably in association with stainless steel, titanium, Hastelloy®, or Inconel®, or brass.

14. Heat exchanger tube insert, comprising a fixing device (100 to 110) according to any one of the preceding claims and a rotating movable element (200, 201) comprising a rigid helical winding of a rod comprising several turns (20, 21), said rotating movable element (200, 201) comprising: - a first end fixed to the trunnion (120) of said fixing device allowing free rotation of said rotating movable element (200, 201) about itself around the Z axis of said tube (1) under the action of a fluid passing through said tube (1), and - a second free end.

15. Insert according to claim 14, wherein the rotating movable element (200, 201) further comprises a rotating drive piece (30) disposed between said fastening device and said rigid helical winding, and connected in a rotationally fixed manner with said rigid helical winding and said trunnion of the fastening device, said rotating drive piece (30) comprising a shaft (3a) coaxial with said rigid helical winding and provided with at least two blades (30b) fixed to said shaft.

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