EP3719435B1 - Insert for pipe end - Google Patents

Description

The invention relates to an assembly comprising a conduit and an insert according to claim 1.

The duct can in particular be a tube of a heat exchanger, for example used in industry, in particular petroleum or petrochemical.

There are devices, so-called fouling reducers, installed in a movably rotating manner inside heat exchanger tubes with the aim of preventing possible fouling due, for example, to suspended impurities or deposits. from mineral salts dissolved in the fluid, to coke being formed in a thermal cracking process or to sulfur-containing species soluble in hydrocarbons.

Such devices are described for example in the applications EP 0 174 254 , EP 0 233 092 , FR 2 637 659 , EP 0 282 406 , EP 0 369 851 and EP 1 227 292 of the Applicant. They have in common a movable element, generally in the form of a circular helix, fixed to the upstream end of the conduit so as to be able to rotate freely in the latter under the effect of the flow of the fluid. FR 2 975 754 A1 discloses an assembly according to the preamble of claim 1.

It is known to provide an insert at the downstream end of the duct in order to be able to retain the fouling reduction device described above in the event of separation from the duct.

An insert of the type known from the prior art, such as that of the figure 1 , comprises a linear element wound in a circular helix, of external diameter slightly greater than the internal diameter of the duct in which the insert is received. The insert is thus held by resting on the internal walls of the duct.

The linear element extends between a gripping element, outside the conduit, and an end loop inside the conduit. This end loop is closed.

However, this type of insert is relatively difficult to install.

There is therefore a need for a duct end insert bearing on the internal walls of the duct and allowing easier and faster installation.

There is provided an assembly according to claim 1.

Due to this opening, the linear element may be easier to introduce into the duct. If the end loop has the same diameter as the rest of the helical winding, this winding can for example be tilted in order to proceed with this introduction.

Once the free end of the insert has been introduced into the duct, the rest of the winding can be relatively easy to introduce by forcing slightly on the linear element so as to locally increase the pitch of the helix and reduce its diameter. external.

The end loop being open, the end of the linear element can be moved slightly during this force passage, without coming into abutment against another portion of the linear element.

When installed inside the duct, the insert rests against the internal walls of the duct. In other words, it is mounted in a fixed manner inside the duct, with no possible relative movement with respect to the duct. This fixed assembly results from the support (of the forces) of the at least one large diameter loop against the internal walls of the duct. The difference between the external diameter of the at least one large diameter loop (when the insert is out of the conduit) and the internal diameter of the conduit may in particular be sufficient to prevent any movement of the insert relative to the conduit when the The linear element is inside the duct. This difference can be determined by a person skilled in the art, in particular by tests.

In one embodiment, the insert may comprise at the second end a gripping element, for example in the form of a torsion spring, or alternatively simply the last loop of the winding.

The second end can for example be placed outside the conduit, while the first end is inside the conduit. Alternatively, the second end can also be received in the duct, it being understood that it is then closer to the opening of the duct than the first end.

In one embodiment, the end loop may form the first end of the insert. Alternatively, an element can be provided between this first end and the end loop, for example a rod extending longitudinally beyond the winding.

In particular, the large diameter loop can have an external diameter strictly greater than the external diameter of the end loop.

Alternatively, only an end portion of the end loop has a smaller radius of curvature.

Thus, the end loop is open and, at least in part, may have a smaller radius of curvature than one or more loops, so that the device may be even easier to introduce into a duct. .

In one embodiment, at least one end portion of the end loop has an external radius of curvature strictly less than half the internal diameter of the duct.

For example, the end loop has an external diameter that is strictly less than the internal diameter of the duct.

Thus, the linear element can be wound into a helix which is not cylindrical from end to end.

Alternatively, the linear element can thus be wound into an end-to-end cylindrical helix, provided that it has an open free end.

By "wound in a helix" is meant both a helix in the geometric sense of the term (that is to say that the body can be shaped so that, the linear element being assimilated to a curve, the tangent in each point of at least a portion of the linear element makes a constant angle with the longitudinal direction) than any helical winding. In other words, the pitch between the loops may or may not be identical from one end of the body to the other, or from one end to the other of the additional loop (s). For example, provision can be made for the angle between a given direction and the tangent to vary (continuously or not) from one point to another.

The invention is not limited to conduits of circular section either. In the case of a duct of elliptical or rectangular section, the winding could be circular, or else elliptical. In this case, it will be understood that the term “diameter” is understood to mean the smallest dimension of a profile, for example the diagonal in the case of a duct with a rectangular section.

At least one pitch of the helical winding can advantageously be greater than the thickness of the linear element, for example greater than or equal to twice this thickness.

Advantageously, at the level of the at least one large-diameter loop, the pitch (s) of the winding can advantageously be greater than the thickness of the linear element, for example greater than or equal to double of this thickness.

In one embodiment, the end loop may have a smaller pitch than the pitch of the at least one large diameter loop. In particular when the angle between the longitudinal direction and the linear element is identical at the level of the end loop and of the large diameter loop (s). But the angle between the longitudinal direction and the linear element may alternatively be different at the end loop and at the large diameter loop (s). For example, this angle can be smaller at the level of the end loop, or alternatively higher.

The invention is not limited to a particular form of the gripping element.

For example, a torsion spring could be provided, one end of which is in one piece with the other end loop of the winding (second end side) and the other end of which is free, arranged so as to exert forces tending to press a loop of the body towards the wall of the duct.

The linear element can be metal, plastic, or the like.

The assembly may include, in addition to the conduit and the insert fixed to one end of the conduit, a fouling reduction device fixed to the other end of the conduit. The fouling reduction device comprises a linear element rotatably mounted in the duct and of larger external diameter strictly less than the internal diameter of the duct. The insert can be attached to the downstream end and the fouling-reducing device to the upstream end: in the event of separation of the fouling-reducing device, it is driven by the fluid and is stopped in its course by the insert. The insert is thus a retention device for a fouling reduction device.

The insert may comprise at its first end a fastening element of a linear fouling-reducing element, this fastening element and this linear element being shaped so that under the effect of the flow of fluid, the linear reducing element fouling can be rotated and thus scrapes against the walls of the duct, limiting fouling. Thus, the insert serves as a fixing head for a fouling reduction device.

The fastener may for example comprise a rod extending longitudinally through the coil of the insert and terminating at the first end in a hook to which a fouling reduction coil can be attached.

The assembly may for example comprise a head insert for fixing to a fouling reducing device and / or a retention insert for a fouling reducing device.

There is also proposed a heat exchanger comprising one or more assembly (s) as described above, this or these assembly (s) being received in an envelope.

A heat exchanger may include a plurality of conduits through which a fluid passes, and at least one conduit end insert as described above attached to one end of at least one of said conduits.

Each duct receiving an insert can advantageously have an internal diameter greater than the external diameter of the end loop of the insert, and strictly less than the largest diameter of the winding.

The conduits can be received in an envelope called a shell and in which a coolant circulates in order to carry out heat exchanges without direct contact between the fluids. The calender may extend longitudinally parallel to the ducts, and have a section of dimensions of the order of one meter.

In order to force the fluid between the conduits and the internal walls of the calender to circulate between the conduits, transverse plates supporting the conduits can be provided.

The heat exchanger may comprise for at least one duct, a fouling reducing device mounted at the upstream end of said duct and an insert for retaining said fouling reducing device, said insert being mounted at the downstream end of said duct. . The fouling-reducing device and / or the retention insert may be as described above, with an open loop in order to facilitate its or their insertion into the duct.

The invention is not limited to particular dimensions or proportions, but advantageously, the length of the winding, in the longitudinal direction, can be between 1.5 and 10 times longer than the largest diameter of the body. .

In one embodiment, the coil may have a length of between 1 centimeter and 20 centimeters, advantageously between 3 and 5 centimeters.

The largest external diameter of the winding can advantageously have a length between 5 millimeters and 10 centimeters, advantageously between 1 and 2 centimeters.

The outer diameter of the end loop can advantageously have a length between 4 millimeters and 9.95 centimeters, advantageously between 0.9 and 1.9 centimeters.

In an advantageous embodiment, the difference between the largest external diameter of the winding and the external diameter of the end loop may be less than 1 centimeter, advantageously less than 5 millimeters, advantageously less than or equal to 2 millimeters. We can for example choose a difference close to a millimeter.

In an advantageous embodiment, the ratio between the external diameter of the end loop and the largest external diameter of the winding can be between 0.5 and 0.99, for example between 0.9 and 0, 95.

• [Fig 1] La figure 1 représente deux inserts du type connu de l'art antérieur.
• [Fig 2] La figure 2 est une vue schématique de cet exemple d'insert du type connu de l'art antérieur.
• [Fig 3] La figure 3 représente un exemple d'ensemble selon un mode de réalisation de l'invention.
• [Fig 4] La figure 4 est une vue schématique de l'exemple d'insert représenté sur la figure 3.
• [Fig 5] La figure 5 est une vue schématique d'un exemple d'échangeur de chaleur selon un mode de réalisation de l'invention.
• [Fig 6] La figure 6 montre un exemple d'insert pour un ensemble selon un mode de réalisation de l'invention.

The invention is now described with reference to the appended non-limiting drawings, in which:

• [ Fig 1 ] The figure 1 shows two inserts of the type known from the prior art.
• [ Fig 2 ] The figure 2 is a schematic view of this example of an insert of the type known from the prior art.
• [ Fig 3 ] The figure 3 represents an example of assembly according to one embodiment of the invention.
• [ Fig 4 ] The figure 4 is a schematic view of the example of an insert shown in figure 3 .
• [ Fig 5 ] The figure 5 is a schematic view of an example of a heat exchanger according to one embodiment of the invention.
• [ Fig 6 ] The figure 6 shows an example of an insert for an assembly according to an embodiment of the invention.

With reference to figures 1 and 2 , which will be discussed simultaneously, examples of insert of the type known from the prior art have been shown. Each of the inserts 1, 1 ', 1 "comprises a coil 2, 2', 2" and a gripping element 3, 3 ', 3 ".

In these examples, the winding and the gripping element are in one piece, the winding and the gripping element being made from a single linear element.

The windings 2, 2 ', 2 "each comprise a relatively stiff, helically wound metal wire.

Each winding 2, 2 'comprises four loops having an identical or substantially identical pitch, and a closed end loop.

The 2 "winding consists of two loops of identical pitch and a closed end loop.

Each of these closed end loops can have a zero pitch, i.e. at the end the linear element is wound in a circle, or alternatively a very small pitch, less than twice the thickness. of the linear element.

In the example of figure 2 , the end loop has a zero pitch while the loops preceding this end loop have a pitch of 8 mm.

• dans l'exemple de la figure 2 ce diamètre extérieur et de 5,6 mm.
• en référence à la figure 1 le diamètre extérieur du corps 2 est plus élevé que le diamètre extérieur de l'enroulement 2'. Le dispositif 1 est destiné à un conduit de plus large diamètre que le dispositif 1'.

All loops including the end loop have the same outer diameter:

• in the example of figure 2 this outer diameter and 5.6 mm.
• with reference to the figure 1 the outer diameter of the body 2 is greater than the outer diameter of the winding 2 '. The device 1 is intended for a duct of larger diameter than the device 1 '.

The gripping elements 3, 3 ', 3 "are in these examples of the torsion spring type.

With reference to figures 3 and 4 , which will be commented simultaneously, there is shown an example of insert 11 for an assembly according to one embodiment of the invention.

This insert 11 comprises a winding 12 and a gripping element 13. In this exemplary embodiment, the winding 12 and the gripping element 13 are in one piece, the winding 12 and the gripping element 13. being made from a single linear element 21.

The linear element can be a relatively stiff metal wire 21.

At the winding 12, the linear element 21 is helically wound around a longitudinal axis (D), and defines loops 16, 17, 18, 19, 20.

The gripping element 13 may be shaped so as to form a torsion spring.

One 14 of the branches of this spring is in the continuity of a last loop 16 of the winding 12.

The other 15 of the branches of this spring can exert forces tending to press this loop 16 on a wall of a duct 30 when the insert 11 is installed in this duct 30, as illustrated in FIG. figure 3 .

The set represented on the figure 3 therefore comprises a cylindrical duct 30 and an insert 11 chosen so that the external diameter of the loops of larger diameter 16-19 is slightly greater (when the insert 11 is out of the duct 30) than the internal diameter of the duct 30. Thus when the insert 11 is introduced into the duct 30, these loops 16-19 exert forces against the walls of the duct, thus ensuring the attachment of the insert 11 in the duct 30.

The loops 16, 17, 18, 19 have the same diameter and the same pitch. The portion of the winding corresponding to these loops 16 to 19 therefore has the shape of a circular cylindrical helix, inscribed in a cylinder of revolution (with a circular base).

On the other hand, in this example, the end loop 20, located opposite the fixing element 13, has a smaller diameter than the diameter of the loops 16 to 19.

The pitch of this last loop 20 can advantageously be greater than or equal to twice the thickness of the linear element. In other words, this end loop 20 is open. In other words, the winding can be helical from end to end.

In this embodiment, the pitch of the end loop 20 is close to the pitch of the loops 16 to 19.

For example, provision can be made for the tangent at each point of the linear element 21 at the level of the loop 20 to form the same angle with the longitudinal direction as at the level of the loops 16 to 19, as in the example of figures 3 and 4 .

Alternatively, in an embodiment not shown, the end loop 20 could correspond to an angle different from that corresponding to the loops 16 to 19.

In another embodiment not shown, provision could also be made for the loops 16 to 19 to have different pitches from one loop to another, or even for the angle formed with the longitudinal direction to vary continuously along the length of the loop. linear element 21.

To return to figures 3 and 4 it can be noted that the external diameter of the end loop 20 is only slightly less than the external diameter of the loops 16 to 19. In this example, the external diameter of the end loop 20 is 14.2 mm then than the outer diameter of loops 16 to 19 is 15.2 mm. The difference is therefore only 1 mm, but this may be sufficient to facilitate the insertion of the device 11 into a duct of for example 15 mm in internal diameter.

With reference to the figure 5 , there is shown a heat exchanger 40 comprising a casing 41 called a shell having an internal diameter of 1 meter for example and in which is mounted a circular metal plate 42 pierced with orifices 43, 43 '. The perforated circular plate 42 extends in a plane normal to the longitudinal direction of the calender 41.

The calender 41 is further partitioned by means not shown (for example a horizontal partition, or other conduits in the continuity of the conduits 30) into an incoming fluid flow passage 44 and an outgoing fluid flow passage 45.

For each orifice 43, 43 ', a duct 30 is mounted tight, the orifice 43 constituting an upstream or downstream end opening of this duct.

The exchanger is shaped so as to force the fluid circulating in the passage 44 to enter the openings 43 ', and in the same way, the fluid coming from the openings 43 leading to the passage 45 is blocked by the circular plate 42 and s 'flows through passage 45.

The conduits 30 corresponding to the passage 44 thus receive at their upstream end an insert 111 of the type of that shown in figure 6 , serving as a fixing head for a fouling reducing winding 211.

As regards the passage 45, each duct 30 opening onto this passage receives at its downstream end an insert 11, of the type shown in FIG. figure 3 , used for the retention of a respective fouling reducing device installed upstream of the duct and not shown.

With reference to the figure 6 , an insert 111 serving as a fixing head for a fouling reduction device extends between a first end 113 and a second end 114.

This insert comprises a winding defining loops 118-120. It will be noted that the loop 120 closest to the first end is open and of slightly smaller radius of curvature than the other loops 118-119.

These loops 118-119 have an external diameter slightly greater than the internal diameter of the duct, not shown, into which this insert is introduced via its first end 113.

Winding continues on the side of the second end with a set of compact loops 117. The last compact loop on the second end side abuts against an edge 116 of cylinder 115.

The cylinder 115 is crimped to a rod 121 passing through the coil and extending inwardly of the conduit beyond the loop 121.

The rod assembly 121 plus cylinder 115 is thus rotatably mounted on the winding 117-120.

The rod 121 ends in a hook 122 for the installation of a fouling reducing winding. This fouling-reducing element is thus rotatably mounted on a head 111 resting on the duct (not shown) via its large loops 118-119.

The cylinder 115 constitutes a gripping element capable of being grasped by an operator wishing to install or remove the insert 111 from the duct.

Claims (9)

1. An assembly comprising a pipe (30) in which a fluid is intended to circulate and a pipe end insert (11), this end insert extending longitudinally between a first end (20) and a second end (13), said insert comprising

   a linear element (21) wound in a helix and defining a set of at least two and at most fifteen loops (16-20) about the longitudinal direction, said linear element being arranged in the pipe so that its longitudinal direction coincides with a flow direction of the fluid in the pipe, the first end being located more towards the interior of the pipe than the second end,

   wherein
   the set of loops comprises at least one loop (16-19), called a large diameter loop, inside the pipe and whose external diameter when the insert is taken out of the pipe is strictly greater than the internal diameter of the pipe, and

   wherein
   an end portion of the helically wound linear element corresponding to the first end defines an open loop (20), called an end loop,

   and characterised in that when the insert is out of the pipe, said large diameter loop (16-19; 118, 119) has an outer diameter strictly greater than twice the outer radius of curvature of an end portion of the end loop (20; 120).
2. The assembly according to claim 1, wherein the end loop (20; 120) has a pitch smaller than the pitch of said at least one large diameter loop (16-19; 118-119).
3. The assembly according to any one of claims 1 or 2, wherein the linear element (21; 121) is shaped so that the tangent at each point along at least a portion of the linear element forms a constant angle with the longitudinal direction.
4. The assembly according to any one of claims 1 to 3, wherein the ratio between the outer diameter of the end loop (20; 120) and the largest outer diameter of the linear element is between 0.5 and 0.99.
5. The assembly according to any one of claims 1 to 4, wherein the largest external diameter of the insert (11; 111) is between 5 millimetres and 10 centimetres.
6. The assembly according to any one of claims 1 to 5, wherein the insert (11; 111) further comprises a gripping element (13; 115) at its second end.
7. The assembly according to any one of claims 1 to 6, wherein the insert (11; 111) further comprises at its first end a fastening element (121, 122) for a linear fouling-reducing element (211), this fastening element and this linear element being shaped so that the linear fouling-reducing element can be rotated under the effect of the fluid flow.
8. A heat exchanger comprising a plurality of assemblies according to one of claims 1 to 7 housed inside a casing (41).
9. The heat exchanger according to claim 8, further comprising, for at least one pipe, a fouling-reducing device (111, 211) mounted at the upstream end of said pipe and an insert (11) for retaining said fouling-reducing device, said insert being mounted at the downstream end of said pipe.

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