FR3113610A1 - WIRED PACKING FOR A MATERIAL EXCHANGE DEVICE - Google Patents

Abstract

Wire packing, comprising wires, for a material exchange device, said wires having a cross section whose general shape is a polygon shape, at least one of the sides of said polygon being concave and/or convex. Packed column, comprising said wired packing, and a liquid distributor, in particular a wired liquid distributor, for supplying the packing.

Description

WIRED PACKING FOR A MATERIAL EXCHANGE DEVICE

The invention relates to a wired packing, that is to say comprising wires, or even consisting of wires, for a material exchange device, in particular for a gas/liquid exchange device such as a column to distill.

The technical field of the invention can generally be defined as that of packings for material exchange devices, also called packed columns, in particular for gas/liquid exchange devices such as distillation columns. , absorption columns (with or without chemical reaction) and gas scrubbing columns.

PRIOR ART

A packed column, whether it is a distillation column or other, is a column which is filled with elements making it possible to increase the contact surface between a gaseous phase and a liquid phase.

The packing creates a series of obstacles on the path of the liquid and the gas within the column and allows:

• increase the contact surface between the two phases;
• to increase the residence time of the two phases in the column and therefore their contact time;
• to create a turbulent regime in the gas phase, and recirculation in the liquid phase.

The efficiency of a packed column depends on the area of the packing, the contact time between the two phases, gaseous and liquid, and the hydrodynamics within each phase. These phases must be brought into contact in a homogeneous manner over the entire length of the column and over the entire section.

Moreover, in the material and energy transformation industries, and in particular in the chemical industry, the energy costs are mainly due to the separation processes which are generally thermal separation processes, and distillation remains the main factor. one of the most important thermal separation processes in the chemical process industry.

Nevertheless, despite its many advantages and its widespread use, the major disadvantage of distillation is its high energy requirements. Indeed, distillation can generate more than 50% of the operating cost of an installation. It alone represents 40% of the total energy consumed by the chemical industry, and around 3% of global energy demand.

Reducing the energy consumption of distillation columns is therefore a major challenge in the current energy context.

The distillation columns can be tray columns or packing columns as defined above. Linings can also be called "internal".

The packings currently marketed are of two types, namely structured packings and bulk packings or more simply packings. However, these two types of packing are based on the same principle, namely the flow of a liquid film on a flat surface.

One of the first structured packings is described in document US-A-4,296,050 [1].

This packing consists of sheets, corrugated sheets 0.1 mm thick, on which a liquid film flows. Grooves and perforations are machined, which improves the distribution of the liquid, and therefore makes it possible to optimize gas/liquid mass transfers. This is how Mellapak® type packings are made.

The usual geometric surfaces of these packings are between 125 and 750 m²/m ³ , for void ratios ranging from 90 to 98%.

Since 1981, the improvements made to these packings, which are described in particular in patent applications, and which make it possible to increase their performance, are:

• modification of the surface condition of corrugated sheets, most of the time by adding asperities or perforations which will create turbulence and improve wettability;
• the machining of slats made up of twisted elements equipped with notches;
• the addition of flat walls between the corrugated sheets.

The sheets can also be replaced by metallic woven fabrics. These woven fabrics develop large contact surfaces and thus increase the transfer efficiency significantly. However, it seems that these packings require low-fouling fluids and a very homogeneous liquid distribution. In addition, these packings are limited to thin beds because they are unable to maintain good liquid distribution over a great height. Finally, due to their very tight mesh, these packings consisting of woven metal fabrics have a low hydrodynamic capacity. For these reasons, these packings are not or little used on an industrial scale, but rather only on a laboratory pilot scale. Although the geometric modifications of structured packings have been the subject of numerous works and patents in recent years, the main routes followed do not constitute a significant technological breakthrough and do not bring significant improvements compared to the packing described in the document [ 1].

When it comes to bulk packings, the two basic geometric shapes of these packings are ring shape and saddle shape. Improvements to these two basic geometric shapes have resulted in rings and saddles with openings (Pall® Rings and IMTP®); but this is not a fundamental break with reference geometry.

Over time, existing packings, whether structured packings or bulk packings, have been modified with a view to minimizing pressure drop while maintaining constant separation efficiency, or even with a view to improve both capacity and separation efficiency. The modifications have always been determined by the manufacturing processes available for these packings. Traditionally, plastic bulk-type packings are made by moulding, injection or extrusion, while metallic structured packings are produced by bending, cutting and joining thin steel sheets. These packing manufacturing processes prevent them from being made to measure in order to achieve the best performance, because the geometric structure obtained is essentially determined and limited by the possibilities of the manufacturing process, and not by the requirements of optimal performance.

Finally, the structure of the current packings if it is not optimal, because of the manufacturing processes, is also because of a lack of knowledge of the main parameters influencing the gas-liquid mass transfer. Indeed, the mass transfer mechanisms that occur in packings are still difficult to model at small scales.

Recently, packings consisting of yarns, and generally having a lattice structure (“ lattice ”) have been proposed.

Indeed, the flow of liquid, in the form of a film, on a wire forming part of a packing, has an interfacial surface greater than the geometric surface of the wire.

On the other hand, in the case of packings constituted by plates, the interfacial surface of the flow of liquid on a plate is more or less equal to the geometrical surface (by neglecting the waves at the interface and the problems of wettability).

Thus, for the same geometric surface, the interfacial surface is higher for a packing consisting of wires than for a packing consisting of plates, in the case where the entire surface of the wire is wetted by the liquid.

These packings made up of wires, and generally having a latticed structure, also called wired " lattice " packings, can have different geometries, in particular a geometry with a fractal structure created by the assembly of regular tetrahedrons or a geometry created by the assembly of structures analogs to DNA.

These packings are more efficient in terms of mass transfer and pressure drop than the known structured packings.

Nevertheless, the wires used in these packings have a circular section and their surface area is therefore still insufficient.

This is the reason why packings consisting of wires with a polygon-shaped section, in particular a triangular section, have been developed. Packings with polygon-shaped wires have the same efficiency in terms of material transfer as packings with circular-section wires, and they make it possible to obtain a gain in surface area for the same void ratio.

However, the surface of these packings consisting of wires with a polygon-shaped cross-section, in particular a triangular cross-section, still remains insufficient.

There is therefore, in the light of the foregoing, a need for a packing having improved performance, which makes it possible to reduce the energy consumption of packed columns, in particular packed distillation columns.

In particular, there is a need for a packing that has improved performance in terms of material transfer (appreciated in particular by the Equivalent Theoretical Plate Height - HEPT) and pressure drop, as well as an increased surface area.

There is still a need for a packing which does not have the disadvantages, defects and disadvantages of the packings of the prior art, such as those described above, and which solves the problems posed by the packings of the prior art.

Finally, there is a need for such a packing which can be manufactured simply, easily, and at lower cost, even if it has a complex shape.

This object, and still others, are achieved, in accordance with the invention, by a packing comprising wires, for a material exchange device, said wires having a cross section whose general shape is a polygon shape, at least one of the sides of said polygon being concave and/or convex.

The packing according to the invention can be called wire packing. By wire packing is generally meant packing comprising wires, preferably consisting of wires.

By concave side, we mean that this side has a rounded shape towards the inside of the wire, is curved towards the inside of the wire.

By convex side, we mean that this side has a rounded shape towards the outside of the wire, is curved towards the outside of the wire.

The threads of the packing according to the invention can be solid threads, which do not have an internal channel or cavity, or else these threads can be hollow threads, with an internal channel or cavity, this channel or this cavity being closed off, clogged , in particular at its ends, so that no flow, runoff of liquid can occur in this channel or this cavity.

In all cases, when the threads of the packing according to the invention are brought into contact with a liquid, the flow of the liquid, the runoff of the liquid occurs exclusively on the external surface of the threads.

It should also be noted that when a side is concave, in other words has a concavity, this means that this concavity is generally present over the entire length of the wire, thus forming a gutter over this entire length.

It should also be specified, in addition, that when a side is convex, in other words has a convexity, this means that this convexity is generally present over the entire length of the wire.

The wired packing according to the invention, comprising wires, for a material exchange apparatus, said wires having a cross section having a specific shape of a polygon, of which at least one of the sides is concave and/or convex, has no never been described in the prior art.

The packing according to the invention has improved performance, in particular in terms of material transfer (appreciated in particular by the Equivalent Theoretical Plate Height - HEPT) and pressure drop, compared to known bulk and structured packings, and it has a significantly increased efficiency, for example by 25% or more, compared to the efficiency of these known bulk and structured packings.

The packing according to the invention also has a higher surface area than the packings consisting of wires with a circular section or with a polygonal section without a concave and/or convex side.

Thus, by way of example, a packing according to the invention, consisting of wires of triangular section with three concave sides has, for the same void content and the same diameter (as defined below, namely: the diameter is that of the circle in which the polygon such as a triangle is inscribed), a specific geometric surface (expressed in m ² /m ³ ) at least 20% greater than that of a packing consisting of triangular section wires with flat sides without concavity or convexity.

And, again by way of example, a packing according to the invention, consisting of wires of triangular section with three concave sides has, for the same void content, and the same diameter (as defined below), a specific geometric surface A (expressed in m ² /m ³ ) at least 50% greater than that of a packing consisting of wires of circular section.

The packing according to the invention makes it possible to significantly reduce the energy consumption of the distillation columns by substantially increasing the performance of the packing.

The packing according to the invention makes it possible to reduce, for example by at least 10%, the energy consumption of a distillation column compared to known packings.

The packing according to the invention does not have the drawbacks, defects, limitations and disadvantages of the packings of the prior art and provides a solution to the problems of the packings of the prior art.

Advantageously, said polygon has 3 to 10 sides, preferably 3 to 8 sides.

Advantageously, all the sides of said polygon are concave, and two or more of said sides of the polygon are optionally, in addition, connected by flat sides (without concavity or convexity) of short length compared to the length of the sides of the polygon. By "short length", we generally mean a length less than or equal to 15% of the length of one side of the polygon, more particularly less than or equal to 10%.

For example, this " short length " may generally not exceed 300 μm.

Preferably, the polygon is a triangle, preferably an equilateral triangle, all sides of which are concave, preferably with the same concavity.

In other words, the preferred yarns are yarns with a triangular cross-section, all sides being concave, and the more preferred yarns are yarns whose cross-section has the shape of an equilateral triangle.

The threads of the packing according to the invention may have a diameter of 0.5 to 10 mm, preferably of 1.5 to 4 mm.

Note that the diameter is that of the circle in which the polygon, such as a triangle, is inscribed.

Advantageously, the concave side(s) of the polygon have a concavity with a depth of 50 to 1000 μm, in other words form one or more gutters with a depth of 50 to 1000 μm.

Advantageously, the threads form elementary structures also called basic structures which are repeated, assembled, in space to form the packing.

The elementary structures can be assembled, repeated laterally, horizontally, thus forming layers, and these layers can be assembled vertically to form the complete, total filling.

There is no limitation on the shape of elementary structures also called basic structures. As specified below, the manufacture of these structures by an additive manufacturing technique makes it possible to manufacture structures of very complex shapes.

Advantageously, the elementary structures are polyhedra.

Preferably, the elementary structures are regular or irregular tetrahedrons.

By regular tetrahedron, we mean a tetrahedron whose four faces are identical.

By irregular tetrahedron is meant a tetrahedron of which at least one of the faces has a surface different from the other faces, in particular a tetrahedron which has three identical faces on four faces.

Or, the basic structures (meshes) are springs made up of two coils with the same geometric characteristics. These turns being brought into contact in such a way that the distance between two points of contact is equal to the pitch of the turn.

The packing then consists of an arrangement of interconnected springs.

Advantageously, the wires do not have angles with the horizontal of less than 50° because it allows for better flow. This can apply to all wires making up all types of elementary structures (e.g. springs, polyhedrons such as tetrahedrons).

Thus, it has been observed that the fact of connecting polyhedrons such as tetrahedrons by rounded, curved portions of wire, which do not present angles with the horizontal of less than 50°, in particular which do not present elbows, abrupt, abrupt changes of direction, allowed a better flow.

In the same way, advantageously, the basic, elementary structures (meshs), when it comes to springs made up of two coils, do not have wires whose angle with the horizontal is less than 50°.

Advantageously, the elementary structures are assembled in such a way as not to form preferential flow paths in the packing.

Advantageously, the packing according to the invention comprises from 10,000 to 300,000 threads per m² cross section of the packing, the overall shape of which may be that of a column.

Advantageously, the packing according to the invention has a void content of 85 to 98%.

Advantageously, the packing according to the invention has a specific geometric surface of 100 to 1000 m ² /m ³ .

As already indicated above, such a surface is higher, for the same void ratio, than the surface of packings consisting of wires with circular section or with polygonal section without concave and/or convex side.

The packing according to the invention, even of very complex shape, can be easily, quickly and inexpensively manufactured by an additive manufacturing technique, for example by a manufacturing technique that uses a 3D printer.

The material which constitutes the packing according to the invention is preferably chosen from materials which are resistant to the fluids with which it is in contact, and in particular if these fluids are corrosive and/or at high temperature and/or under pressure.

In other words, the material from which the packing is made is generally chosen so as to be resistant to the chemicals envisaged in the various potential industrial applications.

Advantageously, the material that constitutes the packing according to the invention is also chosen from materials allowing the packing to be manufactured by an additive manufacturing technique, for example by a manufacturing technique that uses a 3D printer.

Preferably, the packing according to the invention is made of a material chosen from ceramics; metals such as aluminum and titanium; metal alloys such as steels, such as stainless steels and carbon steels, and titanium or aluminum alloys; thermoplastic organic polymers and resins, such as ABS, acrylic resins, PE, PP, PVC, C-PVC, PVDF, PTFE, etc. ; and all the materials allowing manufacture of the device by an additive manufacturing technique.

The packing (global, complete), according to the invention, consisting of elementary structures whose shape can be very complex, can in particular have a cylindrical shape which is the most common shape of the devices in which the packing according to the invention can be used.

The packing according to the invention can be used in all materials exchange devices, implementing packings, in particular in gas/liquid exchange devices such as distillation columns and absorption columns.

These devices can be already existing devices in which the packing according to the invention can replace an old packing with lower performance or new devices.

Indeed, distillation remains one of the most important methods of thermal separations. Its field of application is wide and extends from the separation of petroleum to the separation of biomass.

Applications of distillation include:

• Separation of crude oil into different fractions (diesel, kerosene, gasoline, etc.).
• Separation of a solvent and a chemical.
• Desalination and purification of water.
• Distillation of air to obtain oxygen, nitrogen, and argon.
• Separation of fermented products (alcohol, bioethanol).
• Fermentation process from biomass to obtain compounds such as alcohols, carboxylic acids, or platform molecules.
• Purification of a product or a molecule.

The material exchange devices implementing a packing according to the invention can also be called for simplicity “packed columns”.

The invention therefore also relates to a packed column, comprising a packing according to the invention and a liquid distributor for supplying the packing.

There is no limitation on this liquid dispenser which can be any known or unknown dispenser, gravity or pressure.

However, advantageously, this liquid distributor is a wired liquid distributor, that is to say a distributor comprising wires, preferably a distributor consisting of wires.

This wired distributor, which is placed above the packing according to the invention and below m liquid supply orifices of the column, is more preferably a distributor (known as the preferred distributor) comprising a plurality of stages, arranged successively in the vertical direction, in which:

• the first stage (upper stage) of the plurality of stages comprises m wires of a first diameter, each of the m wires being intended to be placed in one of said m supply orifices;

in the following stages of the plurality of stages, in a stage of rank x, each of the wires of the stage of rank x-1 is divided into n wires of a diameter smaller than the, or equal to, the diameter of the son of the floor of row x-1. It should be noted that the number m of supply orifices is generally the number m of supply orifices per m ² of cross section of the supply means such as a tray, and the number m of wires of a first diameter is the number of wires per m ² of cross-section of the first stage (upper stage) of the distributor. This number m can also be the total number of supply orifices (of a plate for example) placed above the distributor, and the total number m of wires of the first stage (upper stage) of the distributor.

The liquid flows through, streams from, the end of the wires of the last stage of the distributor to feed the packing.

It has been found surprisingly that, when the distributor used with the wired packing according to the invention was a wired distributor, and in particular the preferred distributor defined above, the distributor and the packing according to the invention formed a real synergistic combination with in particular a significant improvement in the performance of the packing according to the invention, in addition to the improvements already intrinsically due only to the specific structure of the packing according to the invention indicated in the foregoing.

The wires of the wired distributor can be solid wires, which do not have an internal channel or cavity, or these wires can be hollow wires, with an internal channel or cavity, this channel or this cavity being closed off, plugged, in particular at its extremities, so that no flow, runoff of liquid can occur in this channel or this cavity.

In all cases, when the wires of the distributor are brought into contact with a liquid, the flow of the liquid, the trickling of the liquid, occurs exclusively on the external surface of the wires, outside the wires. The pressure drop is therefore much lower than in distributors in which the liquid flows inside channels.

The preferred distributor is first of all, specifically, a wired distributor, comprising wires, and not open tubes or channels in which the fluid flows, with the aforementioned advantages, and secondly, this distributor has a specific structure in which wires of a first diameter are supplied with liquid, then these wires divide one or more times into other wires with a reduction in the diameter of the wires at each division.

The last floor of this preferred distributor (lower floor, the lowest) therefore has a very high number of wires and the ends of these wires form as many distribution and watering points.

This preferred distributor has a much higher number of watering points than the distributors of the prior art, and, consequently, the number of supply points per square meter of straight section of the packing is also much higher. than in the distributors of the prior art.

Advantageously, the preferred liquid distributor comprises a total of 1 to 30 stages, preferably 4 to 16 stages.

The number of divisions, and therefore the number of stages is limited (i) by the height available between the m feed orifices (which are generally defined in feed means such as a tray), and the packing , and/or (ii) the geometry of the packing, and/or (iii) the geometry of the of the m orifices (generally the geometry of the plate).

m can be an integer from 1 to 3400.

n can be an integer from 2 to 8, preferably 3 to 4, n being able to be identical for all the stages or different for 2 or more stages of the plurality of stages.

Advantageously, the last stage of the plurality of stages comprises from 3400 to 100000 thread/m ² .

Advantageously, the diameter of the wires of the row x stage is smaller than, or equal to, the diameter of the wires of the row x-1 stage in a proportion of 5/10 to 10/10 preferably of 4/5 to 5/5.

The cross section of the wires of the distributor can have any shape.

Advantageously, the wires of the wired distributor (preferred or not) may have a circular cross section, a cross section in the shape of a polygon or a cross section whose general shape is as for the wires of the lining, a polygon shape, at least one sides of said polygon being concave and/or convex.

The terms "concave side" and "convex side" have already been defined above.

Advantageously, said polygon has 3 to 10 sides, preferably 3 to 8 sides.

Advantageously, all the sides of said polygon are concave and two or more of said sides of the polygon are optionally, in addition, connected by flat sides (without concavity or convexity) of short length (see above) compared to the length of the sides of the polygon.

Preferably the polygon is a triangle, preferably an equilateral triangle all sides of which are concave, preferably with the same concavity.

In other words, the preferred yarns are yarns with a triangular cross-section, all sides being concave, and the more preferred yarns are yarns whose cross-section has the shape of an equilateral triangle.

Advantageously, the concave side(s) of the polygon have a concavity with a depth of 0.05 to 1 mm (50 to 1000 μm), in other words form a gutter(s) with a depth of 0 .05 to 1 mm (50 to 1000 μm).

The first stage wires can have a diameter of 2.3 to 10 mm, preferably 2.3 to 8.5 mm

The wires of the last stage of the preferred wire distributor can have a diameter of from 1.7 to 10 mm, preferably from 1.7 to 8.5 mm.

Advantageously, the last stage of the preferred wire distributor comprises from 3400 to 100,000 threads/m ² .

It should be specified that in the case where the wires have a cross section in the shape of a polygon or a cross section whose general shape is a shape of a polygon, at least one of the sides of the said polygon being concave and/or convex, the diameter is that of the circle in which the polygon such as a triangle is inscribed.

The wires of the preferred wired distributor can form elementary structures (base structures) which are repeated, assembled in space to form the distributor with the specific structure described above.

The elementary structures can be assembled, repeated laterally, horizontally, thus forming stages, and these stages can be assembled vertically to form the complete, total distributor.

There is no limitation on the shape of the elementary structures also called basic structures, as it is specified below, the manufacture of these structures by an additive manufacturing technique makes it possible to manufacture structures of very complex shapes.

Advantageously, the elementary structures can be polyhedra.

Preferably, the elementary structures are regular or irregular tetrahedrons.

The terms “regular tetrahedron” and “irregular tetrahedron” have already been defined above.

Advantageously, the wires of the wired distributor (preferred or not) do not have angles with respect to the horizontal of less than 50°, because this allows better flow.

This can apply to all the wires constituting all the types of elementary structures (for example polyhedrons such as tetrahedrons) of the wired distributor.

Thus, it has been observed that the fact of connecting the polyhedra, such as tetrahedra by rounded, curved portions of wire, which do not present angles with respect to the horizontal of less than 50°, in particular which do not present elbows, abrupt, abrupt changes of direction, allowed a better flow. Advantageously, the cross-section of the wires of the wired packing according to the invention, and the cross-section of the wires of the wired distributor (preferred or not), in particular the cross-section of the wires of the last stage of the preferred wired distributor, have the same shape, namely a cross section whose general shape is a polygon shape, at least one of the sides of said polygon being concave and/or convex.

Advantageously, the cross section of the wires of the packing (wired, comprising wires) according to the invention, and the cross section of the wires of the wired distributor, in particular the cross section of the wires of the last stage of the wired distributor, preferred or not, have the same diameter.

Advantageously, the number of threads per square meter of cross-section of the packing (threaded, comprising threads) according to the invention is equal to the number of threads per square meter of cross-section of the threaded distributor, in particular the number of threads per square meter cross-sectional area of the top tier of the preferred wire feeder.

Advantageously, each wire of the wired packing according to the invention corresponds, in particular is in contact, with a wire of the wired distributor.

In particular, each wire of the wire packing according to the invention may correspond, in particular be in contact, with a wire of the last stage of the preferred wire distributor.

Advantageously, the preferred wired distributor, and in particular the last stage of the preferred wired distributor, has a geometry identical to a geometry of the wired packing according to the invention, which is supplied by this distributor.

However, in the wire packing according to the invention, there is no reduction in the diameter or the number of wires. In other words, in the wired packing according to the invention, the last stage of the preferred wired distributor is reproduced over a given height h of the packing, or even over the entire packing.

In particular, the preferred wired distributor, and in particular the last stage of the preferred wired distributor, can be constituted by elementary structures identical to elementary structures which constitute the wired packing according to the invention which is fed by this distributor.

For example, the elementary structures of the preferred wired distributor, and in particular of the last stage of the preferred wired distributor, and of the packing can be polyhedra.

Preferably, these elementary structures can be regular or irregular tetrahedrons.

Advantageously, the wires of the preferred wired distributor, and in particular of the last stage of the preferred wired distributor and of the wired packing according to the invention, do not have angles with the horizontal of less than 50° because this allows better flow. This can apply to all the wires constituting all the types of elementary structures (for example polyhedrons such as tetrahedrons).

These tetrahedrons of the distributor and of the packing can thus be connected by rounded, curved portions of wire, which do not present angles with the horizontal of less than 50°, in particular which do not present elbows, sudden changes of direction, steep, which allows a better flow.

The preferred wired distributor, even of very complex shape, can be easily, quickly and inexpensively manufactured by an additive manufacturing technique, for example by a manufacturing technique that uses a 3D printer.

The material which constitutes the distributor is preferably chosen from materials which are resistant to the fluids with which it is in contact, in particular if these fluids are corrosive and/or at high temperature and/or under pressure.

In other words, the material from which the dispenser is made is generally chosen so as to be resistant to the chemicals envisaged in the various potential industrial applications.

Advantageously, the material which constitutes the dispenser, in particular the wired dispenser, is also chosen from materials allowing the dispenser to be manufactured by an additive manufacturing technique, for example by a manufacturing technique which uses a 3D printer.

Preferably, the distributor, in particular the wired distributor, is made of a material chosen from ceramics; metals such as aluminum and titanium; metal alloys such as steels, such as stainless steels and carbon steels, and titanium or aluminum alloys; thermoplastic organic polymers and resins, such as ABS, acrylic resins, PE, PP, PVC, C-PVC, PVDF, PTFE, etc. ; and all the materials allowing the dispenser to be manufactured using an additive manufacturing technique.

Advantageously, the wire distributor is made of the same material as the packing according to the invention. In other words, the wires of the wired distributor can be made of the same material as the wires of the packing according to the invention that it is intended to supply.

The invention will be better understood on reading the following detailed description of particular embodiments. This description is given for illustrative and non-limiting purposes and is made in relation to the attached drawings.

is a cross-sectional view of the section of a wire of a packing not in accordance with the invention. This section is circular.

is a cross-sectional view of the section of a wire of a packing not in accordance with the invention. This section is triangular.

is a cross-sectional view of a thread of a packing according to the invention, according to a first embodiment, the cross-section of which is triangular, more exactly has the shape of an equilateral triangle, the three sides of the triangle having a concavity, and the concave sides being connected by simple rounded portions located at the vertices of the triangle.

is a cross-sectional view of a thread of a packing according to the invention, according to a second embodiment, the cross-section of which is triangular, more exactly has the shape of an equilateral triangle, the three sides of the triangle having a concavity, and the concave sides being connected by flat sides without concavity located at the vertices of the triangle.

shows the assembly of two regular tetrahedrons forming a packing element according to the invention.

is a cross-sectional top view of the entire packing obtained by assembling the packing elements, consisting of regular tetrahedrons, of the .

shows the assembly of a regular tetrahedron and an irregular tetrahedron forming a packing element according to the invention.

is a top view in cross section of the entire packing obtained by assembling the packing elements of the .

shows a “ spline ” function, namely a fx d92 and d93 spline function defined piecewise by polynomials.

shows the assembly of a regular tetrahedron and an irregular tetrahedron forming a packing element according to the invention, these two tetrahedra being connected by a curved portion of wire, rounded called “ spline ”.

shows a basic structure (mesh) of a packing according to the invention consisting of a spring consisting of two coils.

shows one of the two coils forming the spring of the .

shows a section of the .

shows the parameters defining the turn of the which is one of the two whorls which forms the spring of the .

shows how the whorl of the to give the spring to the .

DETAILED DISCUSSION OF PARTICULAR EMBODIMENTS

Figures 1A, 1B and 1C show the cross-sections of yarns constituting packings.

There shows the cross section of a thread of a filling not in accordance with the invention, the cross section of which is circular. In other words, the wire is cylindrical.

There shows the cross section of a thread of a packing not in accordance with the invention, the cross section of which is triangular, more exactly in the shape of an equilateral triangle. This packing is not in accordance with the invention because the sides of the triangle have neither concavity nor convexity.

There shows the cross section of a wire of a packing according to the invention according to a first embodiment, the cross section of which is triangular, more exactly has the shape of an equilateral triangle. This packing is in accordance with the invention because the three sides of the triangle have a concavity, in other words, the wire has gutters on its three sides and over its entire length. In this embodiment, the concave sides are connected by simple rounded portions located at the vertices of the triangle.

As an example, the wires in Figures 1A, 1B, and 1C have diameters of 2.25 mm.

As an example, the length of the sides, edges of the triangles of the cross section of the wires of Figures 1B and 1C is 1.95 mm.

The depth of the concavities of the grain of the is 350μm

Note that, in the case of the wires of Figures 1B and 1C, the diameter is that of the circle in which the triangle is inscribed.

By way of example, the filling comprising the threads of the has a void ratio ∈ of 90% and a specific geometric surface A of 186 m2/m3.

The filling comprising the wires of the has a void ratio ϵ of 89% and a specific geometric surface A of 234 m2/m3.

The filling according to the invention comprising the yarns of the has a void ratio ϵ of 89% and a much higher specific geometric surface A of 283 m2/m3.

There shows the cross section of a wire of a packing according to the invention, according to a second embodiment, the cross section of which is triangular, more exactly has the shape of an equilateral triangle. This packing is in accordance with the invention because the three sides of the triangle have a concavity, in other words, the wire has gutters on its three sides and over its entire length. In this embodiment, the concave sides are connected by flat sides, flat edges without concavity, located at the vertices of the triangle. These concave sides have a short length compared to the length of the sides.

By way of example, the length of the sides, edges of the triangles of the cross section of the wire of the is 1.95mm.

For example, the length of the sides, flat edges without concavity of the grain of the is 0.3mm.

The depth of the concavities of the grain of the is 350 μm.

The filling according to the invention comprising the yarns of the has a void ratio ϵ of 89% and a geometric area A of 283 m2/m3.

In the filling according to the invention, the threads can form elementary structures (basic structures) which are repeated, assembled in space to form the filling.

According to one embodiment, the elementary structures can be polyhedra such as regular or irregular tetrahedra.

Indeed, to create a wired packing guaranteeing in particular optimum liquid gas contact, the choice of geometry can in particular be based on the concept of fractals, for example the packing can comprise an assembly of regular tetrahedrons, in other words a succession of edges of regular tetrahedra as shown in the which shows the assembly of two regular tetrahedrons forming a packing element according to the invention which is a regular element (it should be noted that in Figures 3A, 3B, 4A, 4B, 5B, 6, 7A, 7C and 8, the wires for simplification are represented with a circular cross section, but it is understood that these wires have in fact, in accordance with the invention, a polygonal section, at least one of the sides of the said polygon being concave and/or convex. , the polygon is an equilateral triangle all sides of which are concave, preferably with the same concavity as shown in Fig. or on the .

All of the packing elements assembled together form the overall packing.

The geometry represented on the allows the liquid from each thread to be separated into three streams. The disadvantage of this configuration is the regularity of the geometry, which induces chimneys unfavorable to mixing and gas/liquid exchanges, as shown in which presents a cross-sectional top view of the entire packing obtained by assembling the packing elements, consisting of regular tetrahedrons of the .

To limit these chimneys, the packing can also comprise irregular tetrahedrons. For example, every other layer of the packing can be composed of irregular tetrahedrons ( ), which modify the geometry and limit the vertical chimneys as shown in the .

There shows the assembly of a regular tetrahedron and an irregular tetrahedron forming a packing element which is an irregular element. On the , the upper tetrahedron is an irregular tetrahedron.

Different wire packings according to the invention can be made from the elements shown in Figures 3A and 4A.

These wire packings according to the invention are designed by modifying the various parameters defining the geometry of the tetrahedrons and elements, namely the diameter of the wire (d _w ) (as already specified, in the case of the packings according to the invention , it is then the diameter of the circle in which the polygon is inscribed ), the length of the regular (l1) and irregular (l2) tetrahedron edges, and the angles (θ1) of the regular tetrahedron edges and the angle (θ2) of irregular tetrahedron (the angles are defined with respect to the vertical). Let us specify that, in the case of regular tetrahedrons then l1 = l2 and θ1= θ2 .

The packings (as a whole) are characterized by the geometric surface Ag (expressed in m ² /m ³ ) and the void volume fraction ∈ (in %).

It is possible to calculate these two characteristics by knowing the parameters mentioned above defining the geometry of the tetrahedrons (angles, lengths and diameter of the wire).

By varying the diameter of the wire (d _w ) and the lengths (l ₁ and l ₂ ) and the angles, this induces different numbers of wires per packing section, a specific surface area and a different void fraction. The nomenclature associated with the packing is as follows: DXd _w -∈-A _g , where D corresponds to the macrostructure model of the packing (for example TS for Tetra Spline: see below), X to the packing material (for example PA for polyamide, Nylon), dw to the diameter of the wire (in mm), ∈ to the void content of the packing (in %) and Ag to the specific geometric surface in (m ² /m ³ ).

It should be noted that the distributor which supplies the packing according to the invention is preferably a wired distributor which is defined by the same nomenclature with the same D, X, d _{w ,} ∈, and A _g .

In addition, a yarn-based filling can be considered as a large number of yarns. Thus, if the intersections are neglected, it is possible to define the surface and the volume of these threads, which makes it possible to obtain a relation between the specific geometric surface area Ag, the void volume fraction ∈ and the diameter of wire d _w .

Whatever the geometry retained, the choice of two parameters among these three parameters will impose the third. This relationship has been verified during studies on different wired packing geometries.

To optimize the geometry, visualizations of the liquid film flows were carried out on a model for studying flows on wires. It was thus observed that a rounding for the intersection of the wires carried out using a “spline” function ( , function fx d92 and d93 spline piecewise defined by polynomials) improves liquid distribution.

There shows the assembly of a regular tetrahedron and an irregular tetrahedron forming a packing element, the top tetrahedron is an irregular tetrahedron and these two tetrahedra are connected by a curved, rounded portion of wire. In other words, the trim element of the includes a “spline” as defined in at the intersection of the wires.

It was noted that the fact of connecting the tetrahedrons by portions of wire rounded, curved, not presenting angles with the horizontal lower than 50°, of elbows, of sudden, abrupt changes of direction, allowed a better flow .

According to another embodiment, the base structures (links) can be springs made up of two coils.

Such a structure, mesh, base, consisting of a spring consisting of two coils, is represented on the .

The spring shown on the , is defined from two whorls whose axis is represented on the .

This turn consists of a wire of diameter d0 and pitch d3 (d11) (Figures 7B and 7C).

The axis of the spiral is vertical. At the high end of the spiral, its radius is d1. At the other end of the turn, after a step of length d3, the diameter of the turn has increased. This increase is characterized by the angle d5.

The base mesh of the , consisting of a spring consisting of two coils is then repeated. The distance between the axes of the base links is d23 (d31) ( ).

It is then possible, in order to build the complete, final packing, by multiplying the repetitions until obtaining a piece of rectangular section which can then be subjected to cutting to obtain the complete final packing corresponding to the geometry of the section of the column.

All the steps, until the final cutting is carried out by 3D printing.

Claims (20)

Packing comprising threads, for a material exchange device, said threads having a cross section whose general shape is a polygon shape, at least one of the sides of said polygon being concave and/or convex. Packing according to claim 1, wherein said polygon has 3 to 10 sides, preferably 3 to 8 sides. Packing according to Claim 1 or 2, in which all the sides of the said polygon are concave, and two or more of the said sides of the polygon are optionally, in addition, connected by flat sides (without concavity or convexity) of short length with respect to the length of the sides of the polygon. Packing according to Claim 3, in which the polygon is a triangle, preferably an equilateral triangle, all the sides of which are concave, preferably with the same concavity. Packing according to any one of the preceding claims, in which the concave side(s) of the polygon form a gutter(s) with a depth of 50 to 1000 μm. Filling according to any one of the preceding claims, in which the threads form elementary structures (basic structures) which are repeated, assembled in space to form the filling. Packing according to Claim 6, in which the elementary structures are polyhedrons. Packing according to Claim 7, in which the elementary structures are regular or irregular tetrahedrons. Packing according to claim 6, in which the base structures (meshes) are springs made up of two coils with the same geometric characteristics. Packing according to any one of Claims 6 to 9, in which the elementary structures are assembled in such a way as not to form preferential flow paths in the packing. Filling according to any one of the preceding claims, in which the threads do not have angles with the horizontal of less than 50°. Filling according to any one of the preceding claims which comprises from 10,000 to 300,000 threads per m² cross-section of the packing. Packing according to any one of the preceding claims, which has a specific geometric surface of 100 to 1000 m ² /m ³ . Packing according to any one of the preceding claims, which has a void content of 85 to 98% Process for manufacturing the lining according to any one of Claims 1 to 14, characterized in that the lining is manufactured by an additive manufacturing technique, for example by a manufacturing technique which implements a 3D printer. A packed column, comprising a packing according to any one of claims 1 to 14, and a liquid distributor for supplying the packing. A packed column according to claim 16, wherein the liquid distributor is a wired liquid distributor, comprising wires. Packed column according to Claim 17, in which the wire distributor is placed above the packing and below m liquid supply ports of the column, and comprises a plurality of stages, arranged successively in the vertical direction, in which :

• The first stage (upper stage) of the plurality of stages comprises m wires of a first diameter, each of the m wires being intended to be placed in one of said m supply orifices;

In the following stages of the plurality of stages in a stage of rank x, each of the wires of the stage of rank x-1 is divided into n wires of a diameter smaller than the, or equal to, the diameter of the wires of the floor of rank x-1. Packed column according to claim 17 or 18, in which the cross section of the wires of the packing and the cross section of the wires of the wire distributor have the same shape, namely a cross section whose general shape is a polygon shape, at least one of the sides of said polygon being concave and/or convex. Packed column according to any one of Claims 17 to 19, in which the number of wires per square meter of cross-section of the packing is equal to the number of wires per square meter of cross-section of the wire distributor, in particular the number of wires per square meter of cross-section of the last stage of the wired distributor according to claim 18.