Structured packing elements with reduced material requirements

Abstract

The present invention relates to a structured packing element for a column for mass transfer and / or heat exchange between a heavy fluid phase and a light fluid phase, the structured packing element having a grid of at least two layers with openings, the openings being surrounded by and separated from one another by separation elements, at least two of the at least two layers being arranged parallel to one another and in contact with one another in the longitudinal direction, such that an open space extending from one end of the at least two layers to the opposite end is provided between the at least two layers, such that at least one of the heavy and light fluid phases can flow therethrough, the average width of at least 50% of the separation element between adjacent openings is at least 15 times the layer material thickness and is between 70% and 125% of the average hydraulic diameter of the adjacent openings, and the maximum distance between at least two of the at least two layers, measured in a plane perpendicular to the longitudinal direction, is four times greater than the average width of the separation element.

Description

[Technical field]

[0001] The present invention relates to structured packing elements for columns for mass transfer and / or heat exchange between a heavy and a light fluid phase. [Background technology]

[0002] Structured packing elements are used in mass transfer columns, for example in fractionation columns, distillation columns, absorption columns, extraction columns, or flue gas scrubbers. The structured packing elements function to improve mass and / or heat transfer between at least two fluid phases of different densities, and the structured packing elements are usually operated in countercurrent flow. In distillation and absorption applications, the light phase is a gas or vapor and the heavy phase is a condensate or liquid, whereas in extraction processes both phases are liquids with different densities. The structured packing elements have multiple different layers, each of which provides a surface area for the heavier phase. The heavier phase flows slowly downward along the surface of the layer and diffuses. In addition, open spaces are provided between the different layers of the structured packing elements, which are filled with the light phase (e.g., in distillation, vapor or gas) and provide a path for the ascending light phase, while the light phase is displaced by the pressure gradient. The pressure gradient is necessary to overcome the flow resistance. In the general case of countercurrent mass transfer, the average flow direction of the light phase is from the bottom to the top of the structured packing element, and thus opposite to the average flow direction of the heavier phase. By allowing one heavy phase to spread over the surface of the structured packing element, an interface is created between at least two phases, so that efficient heat and mass transfer between the phases is established at the interface. Applications with more than two heavy phases may also exist. One example is extractive distillation.

[0003] Mass transfer columns usually have multiple beds of structured packing elements. A distributor is usually placed on top of each bed to distribute the heavy phase evenly across the cross section of the bed while leaving enough space for the light phase to ascend through it. In addition, a grid-like retention device and collector is often placed below each bed, where the grid-like structure keeps the bed in place and the collector collects the heavy phase that slowly flows down from the bed, while leaving enough free space in the collector for the light phase to ascend.

[0004] A common type of structured packing element is the so-called cross-channel corrugated sheet packing, which is assembled from several corrugated sheets, which are parallel to each other and in contact with each other. Usually, the corrugated metal sheets are fixed to each other by several rods that penetrate the corrugated sheets perpendicular to the longitudinal section of the corrugated sheets, and the rods are fixed to the first and last corrugated sheets by washers and nuts or by bending the rods. Each corrugated sheet has several peaks and valleys of alternating orientation, and adjacent corrugated sheets are oriented so that the corrugations of these adjacent corrugated sheets cross the corrugations of the corrugated sheets that run perpendicularly or obliquely to the longitudinal direction, thereby forming inclined channels that continuously cross each other. These channels have a positive influence on the flow of the gas and liquid phases in the packing and promote the mass transfer between the phases. That is, the gas and liquid phases are brought into contact in the channels of the structured packing element, thus promoting the mass transfer and also the heat transfer between the phases. More specifically, the ascending gas contacts the liquid present on the surface of the sheet and forms channels as it flows downward through the mass transfer column. During this contact, components abundant in the gas are transferred into the liquid and vice versa, meaning that efficient mass transfer is occurring. These packings are disclosed, for example, in DE1253673, CA1270751, and U.S. Pat. No. 6,206,349 (B1).

[0005] The amount of mass transfer per unit time is proportional to the interfacial area between the gas and the liquid, and increases as the interfacial area increases with the proportion of the surface of the packing element layer that is wetted by the liquid. Cross-channel corrugated sheet packings made of wire mesh are known to have good wettability and therefore high mass transfer efficiency, thanks to the good diffusion of the heavy phase at the surface of the corrugated sheet by the capillary forces of the wire mesh. Examples of such structured packing elements are the Sulzer packing types BX and CY, first published in the 1960s. Another example of such a structured packing element is disclosed in EP1477224A1. However, metal wire mesh is an expensive material. For this reason, attempts have been made to replace the mesh material with corrugated metal sheets with many small openings. One example is the commercially available Montz-Pak Type BSH. During the operation of the mass transfer column, the openings of this packing are filled with the heavy phase by capillary forces. The wettability of such relatively precisely structured corrugated perforated metal sheets is lower than that of packings based on wire mesh, and the production of the sheets remains relatively expensive, in part due to the slow production process associated with the precise structure.

[0006] As mentioned above, for high mass transfer efficiency, it is important that the surface of the structured packing elements is well covered by the liquid, because the light phase does not contact the heavy phase as much as the physical area of ​​the packing can provide, resulting in insufficiency and wasting packing material. An alternative proposal to promote the spreading of the heavy phase on the surface of the layer (instead of using wire mesh or corrugated very fine expanded metal sheets as material for the structured packing elements) is to provide layers with porosity and other surface textures, as disclosed in US Patent 4,296,050, GB 1,569,828, US Patent 4,981,621, and EP 3003550 A1, among others.

[0007] In order to further improve the use of the surfaces of the structured packing elements, it has already been proposed in DE 3818917 C1 and CN 88200252 U to provide a cross-channel corrugated sheet packing made of a perforated layer with a high porosity (i.e. a high ratio of the total area of ​​the openings in the layer divided by the sheet area of ​​the layer). More specifically, DE 3818917 C1 discloses a structured packing element made of a sheet layer with openings separated from one another by separating elements. The edges of the openings have protruding rims, and the rims of adjacent openings extend alternately upwards from the upper side of the surface of the sheet layer and downwards from the lower side of the surface of the sheet layer. Furthermore, DE 3818917 C1 teaches that the openings of the layer are 3 to 7 times larger than the width of the separating elements located between adjacent openings. This results in a structured packing element made of perforated metal sheets with a very high porosity, of the order of 50% or more. CN88200252U discloses a structured packing element made of a perforated sheet having a thickness of 0.1 mm to 0.5 mm. The openings have a diamond shape, the width of the openings is between 2 mm and 3 mm, and the percentage of the perforated area on the sheet, i.e., the porosity, is 40% to 50%. Thus, both of these prior art documents teach providing a structured packing element with a sheet layer having a very high porosity, which is more than 40%, preferably about 50%. In contrast to these, conventional structured packing elements have a very low porosity, at most about 10%.

[0008] Structured packing elements based on different principles than cross-channel corrugated sheet packing are disclosed, for example, in EP 0069241 A1, US Pat. No. 4,304,738, and EP 0250061 A1. The layers of these structured packing elements are made of expanded sheet metal, which is stretched to a specific layer width. However, unlike cross-channel corrugated sheet packing, the layers of these structured packing elements are not corrugated and do not deform, except for the deformations associated with the stretching process. This limits the free space for ascending vapor. Thus, mass transfer efficiency is not optimal. This is because the free space between the layers does not provide a clearly defined path for the ascending vapor to move in a manner that promotes homogeneous distribution throughout the plane of the cross section of the structured packing element. It is desirable to force the vapor to move in a specific direction by increasing the degrees of freedom when defining the shape of the packing.

[0009] Apart from high mass transfer efficiency, capacity is an important aspect for structured packing elements. As the flow rates of the light and heavy phases in the structured packing element increase, the pressure drop in the structured packing element increases. At a certain pressure drop, gravity is not strong enough to counter the friction between the two phases and the respective heavy or liquid phase mixes with the respective light or gas phase, so that the heavy or liquid phase cannot drop further along the structured packing element. At this point mass transfer stops. This situation is called flooding. This flooding point determines the capacity of the structured packing element, i.e. it is characterized by the maximum flow rate of the pair of counter-flowing phases that the capacity of the structured packing element exceeds when the increase in either of the two flow rates reaches flooding. The flooding point is related to the specific pressure drop, which is typically of the order of 10 mbar per meter of packing height.

[0010] Optimally, structured packing elements have good mass transfer efficiency as well as good capacity, since this allows for a reduction in the diameter and / or height of the mass transfer column at a given capacity and thus minimizes the investment costs of the mass transfer column. However, these two properties depend on opposite trends with respect to the specific surface area and other geometric parameters. More specifically, a large specific surface area, i.e. the ratio of the geometric area of ​​the structured packing element divided by the volume occupied by the structured packing element, leads to a high degree of contact between the light and heavy phases. This is because each structured packing element has a high mass transfer efficiency, usually expressed as the number of theoretical plates (NTSM) per meter of packing height. However, structured packing elements with a large specific surface area are characterized by a high flow resistance for the light phase. This is because each structured packing element has a higher pressure drop per unit height of packing (at a given flow rate of the light phase) and therefore a smaller capacity than packings with a small specific surface area. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] DE1253673 [Patent Document 2] CA1270751 [Patent Document 3] U.S. Patent No. 6,206,349(B1) [Patent Document 4] EP1477224A1 [Patent Document 5] U.S. Patent No. 4,296,050 [Patent Document 6] GB1,569,828 [Patent Document 7] U.S. Patent No. 4,981,621 [Patent Document 8] EP3003550A1 [Patent Document 9] DE3818917C1 [Patent Document 10] CN88200252U [Patent Document 11] EP0069241A1 [Patent Document 12] U.S. Patent No. 4,304,738 [Patent Document 13] EP0250061A1 [Patent Document 14] U.S. Patent No. 5,885,694 [Patent Document 15] EP0995958B1 [Patent Document 16] U.S. Patent No. 6,874,769(B2) [Non-patent literature]

[0012] [Non-Patent Document 1] U.Onken, W.Arlt, "Recommended Test Mixtures for Distillation Columns", 2nd Ed.1990, The Institution of Chemical Engineers, Rugby, England.ISBN0-85295-248-1 [Non-Patent Document 2] MRFenske, Ind. Engg. Chem. 24, 482 pages, 1932 Summary of the Invention [Problem to be solved by the invention]

[0013] In view of the above, the underlying object of the present invention is to provide a cost-effective and versatile structured packing element having a higher mass transfer efficiency at a given volume, or having a larger volume at a given mass transfer efficiency, or having a smaller weight at a given mass transfer efficiency, respectively. [Means for solving the problem]

[0014] According to the invention, this object is achieved by providing a structured packing element for a column for mass transfer and / or heat exchange between a heavy and a light fluid phase, the structured packing element having a grid of at least two layers with openings, the openings being surrounded by and separated from one another by separation elements, at least two of the at least two layers being arranged parallel to one another and in contact with one another in the longitudinal direction, such that a free space is provided between these at least two layers, extending from one end to the opposite end of the at least two layers, such that at least one of the heavy and light fluid phases can flow therethrough, and a free space between adjacent openings of at least one of the separation elements, Also preferably, the average width of at least 50% is at least 15 times the layer material thickness and is between 70% and 125% of the average hydraulic diameter of adjacent openings, the maximum distance between at least two of the at least two layers, measured in a plane perpendicular to the longitudinal direction, is at least 4 times greater than the average width of the separating element, the average width of the separating element is determined by dividing the separating element into individual sections i=1, 2, 3, ... n, each having a section length di, measuring the shortest distance bi between adjacent edges within the section in each of these sections and dividing the sum of the products di·bi by the sum of di to obtain the average width b of the separating element, the layer material thickness being the thickness of the layer material, the layer material thickness being measured at the outer edge of one of the outer edges of the layer by a micrometer screw.

[0015] This solution is based on the surprising discovery that the mass transfer efficiency in a given volume can be significantly improved if the average width of the separating element between adjacent openings is relatively large in relation to the openings (i.e. between 70% and 125% of the hydraulic diameter of the adjacent openings) and even significantly wider than the layer material thickness (i.e. 15 times or more). This was particularly unexpected, since it contradicts the teachings of DE3818917C1 and CN88200252U. These two prior art documents imply that a free-standing film suspended between the separating elements contributes twice to the mass transfer area, and therefore further propose to minimize the width of the separating element and to remove a further part of the physical area. In view of this, it was even more surprising that the mass transfer efficiency in a given volume can be significantly improved by increasing the ratio of the average width of the separating element between adjacent openings divided by the hydraulic diameter of the adjacent openings, compared to the ratio taught in the above mentioned prior art documents.

[0016] Another significant advantage of the structured packing element according to the invention is that it is not based on the use of any expensive layer material. Rather, the grid of layers can simply be produced with expanded sheet material, i.e. by cutting and stretching a thin metal plate and then transforming the expanded sheet metal in a second step, for example into a corrugated sheet. Thus, a cost-efficient raw material is used, the material requirements of which can be further reduced by stretching the raw material. Overall, the invention provides a cost-efficient and versatile structured packing element with a higher mass transfer efficiency at a given volume or a larger capacity at a given mass transfer efficiency, respectively.

[0017] The longitudinal direction of the structured packing element is the direction from the top area to the bottom area of ​​the structured packing element when incorporated into a mass transfer and / or heat exchange column, i.e., the longitudinal direction is the direction from the top to the bottom of the mass transfer and / or heat exchange column. In other words, it is the gravity-driven intended flow direction of the heavier phase during operation of the structured packing element and the mass transfer and / or heat exchange column, respectively. More specifically, the longitudinal direction of the structured packing element can be determined as follows: the structured packing element is arranged on a horizontal area, such that layers of the structured packing elements arranged parallel to each other and in contact with each other extend in the vertical direction, and further such that the open spaces (or channels respectively surrounded and thus defined by the periodically deformed portions of the layers) extending from one end of the layers to the opposite end extend from the top to the bottom of the structured packing element. The longitudinal direction is therefore the direction from the top to the bottom of the structured packing elements so arranged, or in other words: a heavy phase, e.g. water, falling onto the top of a structured packing element so arranged will flow gravity-driven downward along the open space, and the longitudinal direction is the average flow direction of the heavy phase.

[0018] The maximum distance (hereinafter also referred to as "D" or abbreviated as "D") is closely related to the layer width (hereinafter also referred to as "W" or abbreviated as "W"), which is the extension of one monolayer measured in the plane mentioned above. Usually, the value of W is about half of D. The free space between two layers is given by the layer width W. The maximum distance D between two adjacent layers of a structured packing element, measured in a plane perpendicular to the longitudinal direction, means according to the invention the distance between these layers (if the distance between these layers is constant over the entire surface of the adjacent layers, such as in the case of two parallel flat sheets). If the distance between the layers is not constant over the entire surface of the adjacent layers, i.e. if the distance between different surface parts of the layers is different, the maximum distance D between two adjacent layers is the distance between the surface parts of both layers that maximizes the distance in the plane perpendicular to the longitudinal direction between both layers. More specifically, the maximum distance D between two adjacent layers of structured packing elements measured in a plane perpendicular to the longitudinal direction means according to the invention the distance between the two most distant points A and B, where point A is on the first layer and point B is on the second layer. Two parallel planes are defined, one plane containing point A and the other plane containing point B. These two parallel planes are oriented substantially parallel to the orientation of the two layers. Distance D is defined as the distance between these two parallel planes.

[0019] According to the invention, the structured packing element has at least two layers arranged parallel to each other in the longitudinal direction. A parallel arrangement of two layers means, according to the invention, that one of the layers is inclined relative to the other layer at an angle of at most + / - 20°, preferably at most + / - 10°, more preferably at most + / - 5°, even more preferably at most + / - 2°, and most preferably is not inclined at all relative to the other layer.

[0020] Furthermore, according to the invention, at least 50% of the separating elements between adjacent openings have an average width that is at least 15 times the layer material thickness. This means that for at least 50% of the separating elements, the ratio between the average width of the respective separating element and the sheet material thickness is at least 15. Preferably, at least 75%, more preferably at least 80%, even more preferably at least 90%, even more preferably at least 95%, and most preferably all of the separating elements between adjacent openings have a ratio between the average width and the sheet material thickness of at least 15.

[0021] Layer material thickness means the thickness of the material constituting or forming the layer, respectively. For example, if the layer is made by a sheet, such as an expanded sheet, the layer material thickness is the sheet thickness. If the layer material thickness or the sheet thickness, respectively, varies over the area of ​​the layer, the layer material thickness is the thickness of the material forming the layer, measured at the outer edge of one of the outer edges of the layer, for example by a micrometer screw. For example, the thickness of the material forming the layer is measured at at least two, preferably at least three, more preferably at least five locations of one or more of the outer edges with a micrometer screw, after which the obtained values ​​are summed and an average is determined by dividing the sum by the number of measurements. For example, good results are obtained if the thickness is measured at 2 to 20, preferably 2 to 10, more preferably 3 to 10, most preferably 5 to 10 locations of one or more of the outer edges of the layer with a micrometer screw, the different locations being spaced apart from each other by about 3 cm along the outer edge. A micrometer screw is a known measuring device with one fixed and one variable measuring area, the latter being adjustable by means of a precision screw. When the variable measuring area is moved completely to the fixed measuring area, both measuring areas can be in contact or touching each other, respectively. Both measuring areas are flat and circular, and the diameter of both measuring areas is preferably 5 mm to 6 mm.

[0022] According to the invention, if the separating element has a constant width, the average width (hereinafter also referred to as "b" or abbreviated to "b") of the separating element is determined by measuring the distance between two parallel adjacent edges of the separating element. If the separating element does not have a constant width, the separating element is divided into a section of length d i The average width b of the separating element is determined by dividing the separating element into separate sections i=1, 2, 3, ... n, each having a minimum distance b between adjacent edges in the section. i is measured. The product d i b i The sum of the values ​​is d i to obtain the average width b of the separating element. As the non-uniformity of the separating element increases, more and shorter sections have to be selected. Preferably, the number n of separate sections i taken for measurements per separating element is between 1 and 1000, more preferably between 5 and 100, most preferably between 5 and 20 (such as between 8 and 15). For example, 5 sections are selected per cm of separating element.

[0023] Preferably, the average width b of the separating element is determined on a plan view of one of the openings adjacent to the separating element. This is advantageously achieved by taking a photographic image of the opening. The plan view of the opening is along the vertical axis of the plane defined by the adjacent edges of the opening. In some cases, such a plane is not clearly defined. In this case, the most suitable view is obtained by trial and error. A number of photographs are taken, such as at least five photographs or preferably at least ten photographs, from different angles. In this case, the photograph that maximizes the opening is considered as the plan view of the opening. A reference length z may be used to determine the length and size on the plan view. This is best achieved by identifying or marking a particular length z on a real object in the vicinity of the opening and measuring the length of the opening. To scale all other distances measured on the plan view, the ratio between the effective length z' of this distance on the plan view and the distance z measured on the real object is used. For example, if the actual length of the segment width is b i =bi '·(z / z'), where the primed variables denote lengths measured on the plan and the unprimed variables denote actual lengths.

[0024] According to the invention, the hydraulic diameter d of an opening is calculated using the formula 4A / P, where A is the cross-sectional area of ​​the opening and P is the perimeter of the same opening. If the shape of the opening is simple, such as a flat triangle, rectangle, quadrilateral or trapezoid, the cross-sectional area of ​​the opening can be determined by utilizing basic measurement criteria (length and height of the shape) and basic geometric formulas (known from Euclidean geometry). Preferably, the area is determined on the plan view of the opening. Complex shapes can be approximated, with the area A being the area of ​​the opening. j The area of ​​these shapes can be calculated again using basic measurement criteria and basic geometric formulas. The area A of all the determined areas within the opening can be calculated using the following formula: j Summing gives the area A of the aperture. As the aperture shape becomes more complex, more subdivisions are required. Preferably, the number m of separate simple shape sections j taken for measurement is 1 to 1000, preferably 5 to 100, more preferably 5 to 20 (such as 8 to 15). As above, the actual length is determined based on the ratio z / z' defined above.

[0025] The perimeter of an opening of simple shape can be determined using basic criteria of measurement and basic geometric formulas. In the most general case, a plan view of the opening is used. The perimeter of the opening is determined by k (k=1, 2, 3, ...K) individual straight lines P that best approximate the opening and represent the opening as a closed polygon. k The lengths of these lines are summed to get the perimeter P. Again, these lengths are converted to actual lengths using the ratio z / z' defined above.

[0026] Numerical image processing methods can be used to determine the average width b, the area A of the opening and its perimeter P. In this case, the size of the pixel determines the basic unit. To convert pixel-based length and area, the ratio z / z' can be defined in an appropriate manner, for example as described above. The grey value can be used to identify pixels that belong to the isolated element and other pixels that belong to the opening. The area can be calculated in a straightforward manner by adding up the pixels and multiplying the sum by the actual area of ​​the pixel (associated with the real object). The width b of the segment i or length d i When determining, if the width direction is not parallel to the pixel sides, the rules of trigonometry must be applied.

[0027] Further details regarding the measurement methods and illustrative examples are given further below in conjunction with the figures.

[0028] When the grid is produced by stretching sheet metal, i.e., by cutting and stretching the sheet material, the resulting opening is typically a diamond shape with four generally equal side lengths a1 and a short diagonal e2 and a long diagonal e1 (also called characteristic length). Thus, as generally shown in FIG. 9, which will be described in more detail later, each diamond-shaped opening is surrounded by four separating elements, each having a width b, and the separating elements of adjacent openings are connected to each other at contact points. The hydraulic diameter d is generally unknown, but can be determined as described above or calculated from commonly used characteristic dimensions as described later. Expanded sheets are typically characterized by the dimensions of their unit cells and the width b of the separating elements. The unit cells are quadrilaterals (or diamonds) that cover the opening, with the quadrilaterals extending through the midpoints of the four contact points of the separating elements. The unit cells have a short unit cell height u2 and a long unit cell width u1. The short unit cell height u2 is aligned with the short diagonal e2 of the opening, and the long unit height u1 is aligned with the long diagonal e1 of the opening. The stretch direction, which is the direction along which the sheet metal is processed, i.e., cut and drawn, is usually associated with the shorter unit cell height u2. The unit cell dimensions u1 and u2 are different from the diagonals of the openings e1 and e2 through the separating element section, and they must be added together. Given the unit cell dimensions u1, u2 and the separating element width b, the following equation is used to determine the hydraulic diameter of each opening: e1=u1-b√(1+u1 2 / u2 2 ) e2=e1·u2 / u1 d=e1·e2 / √(e1 2 +e2 2 )

[0029] When the ratio of e2 / e1 is about 0.5 or less, as is practical with expanded metal sheets, the following simplified equations for e1 and e2 can be used to determine the hydraulic diameter d of each opening: e1=u1-b u1 / u2 e2=u2-b

[0030] Additionally, expanded metal sheets can be characterized by an expansion factor defined as u2 / 2b. The inverse of this expansion gives a good indication of the material savings that can be realized compared to a solid metal sheet. Further details regarding these dimensions using illustrative examples are provided further below in conjunction with the figures.

[0031] In a further development of the inventive idea, it is proposed that the average width b between adjacent openings of at least 75%, more preferably at least 80%, even more preferably at least 90%, even more preferably at least 95%, and most preferably all of the separating elements is between 70% and 125% of the average hydraulic diameter d of the adjacent openings. More preferably, the average width b between adjacent openings of at least 50%, more preferably at least 75%, more preferably at least 80%, even more preferably at least 90%, even more preferably at least 95%, and most preferably all of the separating elements is between 75% and 100% of the average hydraulic diameter d of the adjacent openings.

[0032] To achieve optimal spreading of the heavy phase on the bed surface, it is preferred that the average width b between adjacent openings of at least 50%, preferably at least 75%, more preferably at least 80%, even more preferably at least 90%, even more preferably at least 95%, most preferably of all separating elements is between 1.5 mm and 4.0 mm. More preferably, the average width b between adjacent openings of at least 50%, preferably at least 75%, more preferably at least 80%, even more preferably at least 90%, even more preferably at least 95%, most preferably of all separating elements is between 1.6 mm and 3.5 mm, most preferably between 1.8 mm and 3.0 mm.

[0033] According to the invention, the average width b of at least 50% of the separating elements between adjacent openings is at least 15 times the layer material thickness (hereinafter also referred to as "s" or abbreviated to "s"). A particularly good determination is obtained if the average width b of at least 50% of the separating elements between adjacent openings is at least 18 times the layer material thickness s.

[0034] In a further development of the inventive idea, at least 50%, preferably at least 75%, more preferably at least 80%, even more preferably at least 90%, even more preferably at least 95%, most preferably the average width b of all separating elements is at least 15 times, preferably at least 18 times the layer material thickness s.

[0035] According to the invention, the maximum distance D between at least two adjacent layers of the at least two layers measured in a plane perpendicular to the longitudinal direction is at least 4 times greater than the average width b of the separating elements. This means that the ratio between the maximum distance D between at least two adjacent layers of the at least two layers measured in a plane perpendicular to the longitudinal direction and the average width b of at least 50%, preferably at least 75%, more preferably at least 80%, even more preferably at least 90%, even more preferably at least 95%, and most preferably all of the separating elements is at least 4. Particularly good results are obtained when the maximum distance measured in a plane perpendicular to the longitudinal direction is at least 4 times greater than the average width of at least 50%, preferably at least 75%, more preferably at least 80%, even more preferably at least 90%, even more preferably at least 95%, and most preferably all of the separating elements between the at least two layers.

[0036] It is further preferred that at least 50%, preferably at least 75%, more preferably at least 80%, even more preferably at least 90%, even more preferably at least 95%, and most preferably all, of the maximum distance D between at least two layers, measured in a plane perpendicular to the longitudinal direction, is at least 5 times, more preferably at least 8 times, greater than the average width b of the separating element.

[0037] In a further development of the inventive idea, it is proposed that the maximum distance D between at least two layers, measured in a plane perpendicular to the longitudinal direction, is at least 50%, preferably at least 75%, more preferably at least 80%, even more preferably at least 90%, even more preferably at least 95%, and most preferably all, is 4 to 15 times, preferably 5 to 13 times, and most preferably 8 to 12 times, greater than the average width b of the separating element.

[0038] In particular, good results are obtained when at least 50%, preferably at least 75%, more preferably at least 80%, even more preferably at least 90%, even more preferably at least 95%, and most preferably all, of the maximum distance D between at least two layers, measured in a plane perpendicular to the longitudinal direction, is between 8 mm and 80 mm, preferably between 12 mm and 51 mm, and most preferably between 16 mm and 30 mm.

[0039] According to a particularly preferred embodiment of the invention, in at least one of the at least two layers, the ratio of the total area of ​​the openings in the layer divided by the sheet area of ​​the layer, i.e. the porosity of the layer, is between 20% and 38%. S is, according to the invention, the sum of the physical area of ​​all the separating elements, measured only on one side, and the total area of ​​the openings enclosed by the separating elements. The total opening is simply the sum of the areas (cross-sectional areas) A of the openings. Furthermore, the sheet area A of the structured packing elements S is the total sheet area of ​​the layers contained in the structured packing element. As mentioned above, the porosity of a packing layer is the ratio of the total area of ​​the openings in that layer divided by the sheet area of ​​that layer.

[0040] Preferably, at least 50%, more preferably at least 75%, even more preferably at least 80%, even more preferably at least 90%, even more preferably at least 95%, and most preferably all of the layers have a porosity between 20% and 38%, which allows the advantages of the invention to be achieved to a particularly high extent.

[0041] Furthermore, it is preferred that at least 50%, more preferably at least 75%, even more preferably at least 80%, even more preferably at least 90%, even more preferably at least 95%, and most preferably all of the layers have a porosity between 25% and 35%, most preferably between 28% and 32%, which leads to a particularly good wetting of the layers of the structured packing element according to the invention.

[0042] Particularly good results are obtained when the grid of structured packing elements is uniform, i.e. when all or at least the majority of the openings and separating elements are equal or at least highly similar to one another. In view of this, it is preferred that at least 50%, more preferably at least 75%, even more preferably at least 80%, even more preferably at least 90%, even more preferably at least 95%, and most preferably all, of the openings of each of the at least two layers have a hydraulic diameter d that is between 50% and 150%, preferably between 70% and 130%, more preferably between 80% and 120%, and most preferably between 90% and 110% of the average hydraulic diameter of all openings.

[0043] It is preferred that at least 50%, more preferably at least 75%, even more preferably at least 80%, even more preferably at least 90%, even more preferably at least 95%, and most preferably all of the openings in each of the at least two layers have a hydraulic diameter d of 1.25 mm to 5.0 mm. It is further preferred that at least 50%, preferably at least 75%, even more preferably at least 80%, even more preferably at least 90%, even more preferably at least 95%, and most preferably all of the openings in each of the at least two layers have a hydraulic diameter d of 2.0 mm to 4.0 mm, and most preferably 2.2 mm to 3.5 mm.

[0044] The present invention is not particularly limited with respect to the geometry of the openings, and thus the openings can have circular, elliptical, generally square, rectangular, diamond, quadrilateral, hexagonal, trapezoidal, polygonal, or irregular cross-sectional configurations.

[0045] For example, good results are obtained if at least 50%, preferably at least 75%, more preferably at least 80%, even more preferably at least 90%, even more preferably at least 95%, and most preferably all the openings have a substantially rectangular or rhomboidal cross section with a side length a1 of 1.0 mm to 5.0 mm, preferably 1.3 mm to 4.0 mm, and most preferably 1.6 mm to 3.5 mm. In this embodiment, it is particularly preferred that the characteristic length (or diagonal, respectively) e2 / e1 of the square or rhomboid is, on average, 0.4 to 0.7, more preferably 0.45 to 0.60, and most preferably 0.49 to 0.55. Furthermore, it is particularly preferred in this embodiment that the average width b of the separating elements between adjacent openings is 1.5 mm to 4.0 mm, preferably 1.6 mm to 3.5 mm, and most preferably 1.8 mm to 3.0 mm.

[0046] According to an alternative embodiment of the invention, at least 50%, preferably at least 75%, more preferably at least 80%, even more preferably at least 90%, even more preferably at least 95%, and most preferably all of the openings have a rectangular or quadrilateral cross section, the shorter characteristic length e2 (i.e. the short diagonal) of the rectangle or quadrilateral is between 1.0 mm and 4.0 mm, preferably between 2.0 mm and 3.0 mm, the longer characteristic length e1 (i.e. the long diagonal) of the rectangle or quadrilateral is between 2.0 mm and 8.0 mm, preferably between 2.5 mm and 7.0 mm, and most preferably between 3.0 mm and 6.0 mm, and the average width b of the separating elements between adjacent rectangles is between 1.5 mm and 4.0 mm, preferably between 1.6 mm and 3.5 mm, and most preferably between 1.8 mm and 3.0 mm.

[0047] The present invention is not particularly limited with respect to the material of the layers of the structured packing element. For example, the layers or grids, respectively, can be made of metal, such as stainless steel or a composite selected from the group consisting of aluminum, copper, titanium, zirconium and alloys. In order to save material and also to produce the grids of the layers of the structured packing element of the present invention cost-effectively, a further development of the idea of ​​the present invention proposes that the grids of at least two layers are made of expanded sheet metal, such as stainless steel or any other metallic construction material, and that the layer material thickness s of each grid is s=0.05 mm to 0.50 mm, preferably s=0.08 mm to 0.20 mm, most preferably s=0.09 to 0.15.

[0048] When producing grids by stretching a sheet, the resulting sheet metal or grid is no longer flat. This is the result of deformation, distortion, bending, or springing of the individual separating elements as well as the relative deformation of the separating elements with respect to the others, e.g. tilting. Other features such as burrs may arise from the drilling process and thus contribute to the thickness. The resulting dimension of the expanded sheet is called the grid thickness g, which can be equal to the layer material thickness (this is the case when the expanded sheet is flat because it has been flattened by rolling) or can be several times larger than the layer material thickness. The grid thickness is usually of the order of magnitude of the width b of the separating elements and should not be significantly larger than width b. Thus, when the grid thickness g is larger than the layer material thickness s, the ratio of the grid thickness g to the average width b of the separating elements ranges from 0 to a maximum of about 1.2, more preferably from 0.4 to 1, and most preferably from 0.5 to 0.8. The grid thickness g is significantly smaller than the maximum distance D between two adjacent layers measured in a plane perpendicular to the longitudinal direction. Preferably, the ratio of maximum distance D to grid thickness g (ie, D / g) is at least three.

[0049] In particular, good results are obtained when the maximum distance D between each adjacent layer of the at least two layers, measured in a plane perpendicular to the longitudinal direction, is at most 15 times greater than the average hydraulic diameter d of the opening.

[0050] As mentioned above, in order to ensure good gas flow in the structured packing element of the present invention, an open space is provided between the layers, which extends from one end of the layer to the opposite end. It is preferred that the open space between at least two layers of the structured packing element is defined by a periodic deformation. In view of this, a further development of the idea of ​​the present invention proposes that at least 50%, preferably at least 75%, more preferably at least 80%, even more preferably at least 90%, even more preferably at least 95%, and most preferably all, of the at least two layers have a periodic deformation, and that the open space between the at least two layers is defined by a periodic deformation. It is particularly preferred that all layers of the structured packing element of the present invention have such a periodic deformation, i.e. that the structured packing element of the present invention does not have any flat layers.

[0051] For example, the periodic deformation portion may be a corrugation having multiple peaks and valleys of alternating orientation, with the peaks of a layer contacting the valleys of an adjacent layer and the valleys of a layer contacting the peaks of an adjacent layer, and these adjacent layers being oriented such that the peaks and valleys of these adjacent layers are crisscrossed with the peaks and valleys of a layer extending obliquely to the longitudinal direction. Of course, not all peaks of a layer contact one or more valleys of an adjacent layer, and it is also possible that some of the peaks of a layer contact one or more valleys of an adjacent layer, and vice versa. However, there should be at least three contact points between two adjacent layers. Preferably, in 30% to 90%, more preferably 50% to 80%, of these locations where the peaks and valleys of adjacent layers face each other, there is no contact. In the remaining locations, the respective peaks and valleys of the adjacent layers touch each other.

[0052] In particular, in this embodiment, good results are obtained if the angle α of each peak and each valley with respect to the longitudinal direction is between 10° and 60°, preferably between 20° and 50°, most preferably between 25° and 47°, with the peaks and valleys of adjacent layers preferably oriented in opposite directions. This allows for a uniform distribution of the light phase on the structured packing element in at least one direction of the cross section. This angle should not be too large in order to minimize the pressure drop and maximize the capacity.

[0053] In order to reduce the pressure loss of the structured packing element, in a further development of the inventive idea it is proposed that the valleys and peaks in the end parts of the layer are bent relative to the valleys and peaks of the central part located between the end parts, so that the flow resistance in the end zone of the structured packing element is reduced relative to the flow resistance of the zones located between the end zones. The peaks and valleys of the layer in this embodiment therefore do not extend linearly. Preferably, the peaks and valleys are bent in the end parts of the layer such that they extend at least substantially vertically. Substantially vertical means that the peaks and valleys do not incline at the lower and upper edges of the layer by more than 10°, preferably more than 5°, more preferably more than 2°, relative to the vertical. The end zones are the uppermost and lowermost zones of the layer, which extend from the upper and lower edges of the layer by 30%, preferably 25%, more preferably not more than 20% along the sheet length, the sheet length being in the direction along the longitudinal direction of the layer. Each of the end zones can have peaks and valleys with different heights than the peaks and valleys of the central zone, the central zone being the zone of the layer between the two end zones. Instead of providing such bends and different heights in both end portions, they may be present in only one of the end zones.

[0054] According to an alternative embodiment of the invention, the periodic deformation portion is a wave having a square, triangular, sinusoidal or meandering type cross section with peaks and valleys, the peaks of a layer contacting the valleys of an adjacent layer and the valleys of a layer contacting the peaks of another adjacent layer, and the adjacent layers are oriented such that the peaks and valleys of the adjacent layers cross each other with the peaks and valleys of the layers extending obliquely to the longitudinal direction.

[0055] In particular, in this embodiment, good results are obtained if the angle α of each peak and each valley with respect to the longitudinal direction is between 10° and 60°, preferably between 20° and 50°, most preferably between 25° and 47°, the peaks and valleys of adjacent layers being preferably oriented in opposite directions, which allows a uniform distribution of the light phase in at least one direction of the cross section of the structured packing element.

[0056] According to yet another embodiment of the present invention, the periodic deformation portion can have a structure as disclosed in U.S. Patent No. 5,885,694, in which two adjacent sheets touch each other at the peaks and valleys of the upwardly and downwardly curving stripes, each sheet having a series of linearly arranged upwardly and downwardly curving stripes, and the lines of two adjacent sheets intersect at a certain angle.

[0057] In accordance with yet another alternative embodiment of the present invention, the periodic deformations are dimples, each of the dimples having a dimple valley wall, and at least a portion of the dimple valley wall of a layer contacting the non-recessed surface portion of an adjacent layer. The dimples may have the form of a crater, i.e., like the dimples of a golf ball. However, it is preferred that the dimples are elongated dimples, such as grooves having an annular cross section.

[0058] However, it is also possible that the free space is not defined by deformation of the layer of the structured packing element itself, but is defined, for example, by one or more spacers provided between adjacent layers, such that the free space between at least two layers is defined by one or more spacers.

[0059] The present invention is not particularly limited with respect to the number of layers contained therein. The number of layers in the packing element is determined by the diameter of the mass transfer column and the specific surface area a required for mass transfer. M It is determined by: If a larger surface is required, i.e. the specific surface area increases, then there will be more layers and the maximum diameter D will decrease accordingly. The structured packing elements have an approximately circular cross section, but depending on the geometry of the heat exchange and / or mass transfer column, other cross sections may also be present, for example rectangular shapes. If the column has a large diameter, the elements are generally subdivided into several segments or tiles in order to reduce the weight and to allow piecemeal mounting.

[0060] The structured packing elements according to the invention are 2 / m 3 750m from 2 / m 3 , 120m 2 / m 3 500m from 2 / m 3 , most preferably 200m 2 / m 3 450m from 2 / m 3 Specific surface area a M A particularly good combination of mass transfer efficiency and capacity is obtained when

[0061] Specific surface area a M is the volume V occupied by the structured packing element. M The geometric area A of the structured packing element divided by M The geometric area A of the structured packing element is defined as Mis the sum of the geometric areas of all layers contained in the element, summed on both sides of the layer as if no openings or holes existed. In other words, the sheet area A of the packing layer S Multiplying by 2 gives us an approximation of the geometric area, since both sides of the layer make up the geometric area.

[0062] Area of ​​openings in the layer and physical area of ​​the layer A P By adding these together, the sheet area A of the structured packing layer is obtained. S A P takes into account only the physically present surface. Holes do not contribute to this value. The sheet area A of the structured packing element S is obtained by adding up the sheet areas of all the layers contained therein.

[0063] Physical area A of the structured packing layer P is the sum of the surfaces, measured on one selected side, of all the separating elements contained in the structured packing layer. The edges of the layer material thickness s do not contribute to this area. The physical area A of the packing P is the total physical area of ​​all layers contained therein.

[0064] Definition for Area a M , A M , A S , and A P Alternatively, the terms "surface" and "surface area" are used in a more qualitative or intuitive manner in the description of the present invention.

[0065] Preferably the structured packing element has a height of 100mm to 300mm, preferably 150mm to 250mm.

[0066] According to another aspect, the present invention relates to a mass transfer column having at least one structured packing element as described above.

[0067] Preferably, the mass transfer column has 1 to 10, more preferably 2 to 8, most preferably 2 to 4 beds, each bed having at least one structured packing element as described above. Preferably, a bed has 2 to 20, more preferably 4 to 15, most preferably 6 to 10 structured packing elements. To achieve very good gas distribution in the beds, two adjacent structured packing elements are rotated along the axis of the column which is generally parallel to the longitudinal direction. The rotation angle is about 50° to about 120°, more preferably about 70° to 110°, most preferably 80° to 100°.

[0068] In addition, the mass transfer column preferably includes a distribution device above each of the beds of structured packing elements to enable at least substantially homogeneous distribution of the heavy phase over the cross-section of the structured packing element beds during operation of the mass transfer column.

[0069] According to another preferred embodiment of the invention, it is proposed that the mass transfer column comprises a collector below the bottom of each bed of structured packing elements, the collector making it possible to collect the heavy phase slowly flowing down the surface of the layer of structured packing elements during operation of the mass transfer column.

[0070] Specific embodiments according to the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0071] [Figure 1] FIG. 1 is a schematic side view illustrating a mass transfer column having a plurality of structured packing elements according to one embodiment of the present invention. [Figure 2a] FIG. 2 is an exploded view of a portion of a sheet of structured packing element according to one embodiment of the present invention. [Figure 2b] FIG. 2b is a schematic side view of the structured packing element shown in FIG. 2a. [Figure 2c]FIG. 2b shows two layers of the structured packing element shown in FIG. 2a. [Diagram 3] FIG. 13 is a partial view of a structured packing element according to another embodiment of the present invention. [Figure 4] FIG. 2 is a schematic diagram illustrating a portion of a structured packing element according to another embodiment of the present invention. [Diagram 5] FIG. 2 is a schematic diagram illustrating a portion of a structured packing element according to another embodiment of the present invention. [Figure 6a] 1A-1D are schematic diagrams showing various embodiments of grid structures of layers of structured packing elements according to the present invention. [Figure 6b] 1A-1D are schematic diagrams showing various embodiments of grid structures of layers of structured packing elements according to the present invention. [Figure 6c] 1A-1D are schematic diagrams showing various embodiments of grid structures of layers of structured packing elements according to the present invention. [Figure 6d] 1A-1D are schematic diagrams showing various embodiments of grid structures of layers of structured packing elements according to the present invention. [Figure 6e] 1A-1D are schematic diagrams showing various embodiments of grid structures of layers of structured packing elements according to the present invention. [Figure 6f] 1A-1D are schematic diagrams showing various embodiments of grid structures of layers of structured packing elements according to the present invention. [Figure 7a] FIG. 1 is a schematic diagram showing the determination of the average width of a separation element and the average hydraulic diameter of the openings. [Figure 7b] FIG. 1 is a schematic diagram showing the determination of the average width of a separation element and the average hydraulic diameter of the openings. [Figure 8] FIG. 1 illustrates the determination of the area of ​​minimum deformation of a structured packing element made of corrugated layers. [Figure 9] FIG. 13 is a plan view to scale illustrating the determination of parameters for a specific example according to the present invention. [Figure 10] 10A-10D are schematic diagrams showing cross sections of packing layers to illustrate the definitions of areas AP (FIG. 10b), As (FIG. 10c), AM, VM, and aM (FIG. 10d). [Figure 11] 1 is a graph showing efficiency curves obtained in Example 1 and Comparative Example 1 at a distillation column top pressure of 960 mbar. [Figure 12] 1 is a graph showing efficiency curves obtained in Example 1 and Comparative Example 1 at a top pressure of the distillation column of 100 mbar. [Figure 13] 1 is a graph showing the pressure drop obtained in Example 1 and Comparative Example 1 at a distillation column top pressure of 100 mbar. [Figure 14] 1 is a graph showing efficiency curves obtained for Example 2 and Comparative Examples 2 and 3 at a distillation column top pressure of 960 mbar. [Figure 15] 1 is a graph showing efficiency curves obtained for Example 2 and Comparative Examples 2 and 3 at a distillation column top pressure of 100 mbar. [Figure 16] 1 is a graph showing the pressure drop obtained in Example 2 and Comparative Examples 2 and 3 at a top pressure of the distillation column of 100 mbar. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0072] FIG. 1 shows a schematic side view of a mass transfer column 10, and more specifically a distillation column 10, according to one embodiment of the invention (the transparent interior of the figure is for illustrative purposes only). Also for illustrative purposes, the grid structure of the layers is not shown in FIG. 1, but only in FIG. 6. The distillation column 10 has a plurality of structured packing elements 12 arranged in the form of two beds 14, 14'. Above each of the two beds 14, 14', a distributor 16, 16' is arranged to distribute the liquid evenly over the cross section of the bed while leaving enough space for the vapor to ascend through it. Below each bed 14, 14', a grid-like retention device 18 and a collector 20 are arranged, the grid-like retention device 18 keeping the bed 14 in its position and the collector 20 collecting the liquid slowly flowing downwards from the bed 14, while leaving enough free space in the collector for the vapor to ascend.

[0073] During operation of the distillation column 10, gas ascends as a light phase from bottom to top, whereas liquid as a heavy phase descends in a countercurrent from top to bottom of the distillation column 10. More specifically, the liquid is substantially homogeneously distributed across the cross section of the bed 14 by the distributor 16 and flows slowly downward along the surface of the layers of structured packing elements 12. Between the different layers of the structured packing elements 12, open spaces are provided, which are filled with gas, and these open spaces provide a path for the ascending gas, during which the gas is moved by the pressure gradient. By allowing the liquid to spread on the surface of the layers of the structured packing elements 12, a large interface is created between the two phases to establish efficient heat and mass transfer between the liquid and the gas at the interface. At the bottom of the bed 14, the liquid is collected in a collector 20 and guided downward via a pipe 22 to the distributor 16' above the second bed 14'.

[0074] Figures 2a to 2c show a structured packing element 12 of the type of so-called corrugated sheet packing. For the sake of illustration, the grid structure of the layers is not shown in Figure 2, but only in Figure 6. The structured packing element 12 is assembled from a number of corrugated sheets 24, 24', which are parallel to one another and in contact with one another. Each of the corrugated sheets 24, 24' is a grid, as described above and as will be explained in more detail later with reference to Figure 6. In the bottom right of Figure 2c, a grid structure is shown diagrammatically, which is part of the corrugated sheet 24. As will be understood from the above specification, at least two, and preferably all, of the corrugated sheets 24, 24' actually consist of such a grid. This is not shown in Figures 2a to 2c for reasons of illustration only. In this embodiment, the corrugated sheets 24, 24' are made of expanded sheet material, i.e. the corrugated sheets 24, 24' are prepared by cutting and stretching a thin metal plate and then transforming the expanded sheet metal into the corrugated sheets 24, 24'.

[0075] The corrugated metal sheets 24, 24' are secured to one another by a number of rods (not shown) that pass through the corrugated sheets 24, 24' perpendicular to the longitudinal sections of the corrugated sheets 24, 24' and the rods are secured to the first and last corrugated sheets by washers and nuts, or by bending the rods, or by any other means (not shown). Each corrugated sheet 24, 24' has a number of alternating peaks 26 and valleys 28, and adjacent corrugated sheets 24, 24' are oriented to crisscross the corrugations 26, 28 of adjacent corrugated sheets 24, 24' with the corrugations 26, 28 of the corrugated sheets 24, 24' that extend obliquely to the longitudinal direction, thereby forming inclined channels 30 that continuously cross each other. More specifically, the angle α of each peak 26 and each valley 28 relative to the longitudinal direction V is between 10° and 60°, preferably between 20° and 50°, most preferably between 25° and 47°, and the peaks 26 and valleys 28 of adjacent layers 32, 32' or 24, 24', respectively, are oriented in opposite directions. The channels 30 define a maximum distance D between adjacent corrugated sheets 24, 24', for example 20 mm. These channels 30 positively influence the flow of gas and liquid phases in the structured packing element 12 and promote mass transfer between the phases. That is, the gas and liquid phases are brought into contact within the channels 30 of the structured packing element 12, thus promoting mass transfer and also heat transfer between the phases. More specifically, the ascending gas contacts the liquid present on the surface of the corrugated sheets 24, 24' and defines the channels 30 as it flows downwards through the mass transfer column. Overall, the light phase flows through each open space or channel 30 and there is no bypass flow through the openings 40 in the grid 38 of the layers 32, 32' of the structured packing element 12. This leads to a particularly efficient mass and energy transfer between the light and heavy phases. Furthermore, the crisscrossing manner of the channels 30 leads to an optimal distribution of the layers from left to right.

[0076] Figure 3 shows a partial view of a structured packing element according to an alternative embodiment. The structured packing element of Figure 3 is similar to the structured packing element shown in Figures 2a to 2c, except that the corrugated sheets 24, 24' do not have linearly extending peaks and valleys, but rather the peaks 26, 26' and valleys of the corrugated sheets 24, 24' are curved in the end zones or portions 33, 33', respectively, and therefore extend substantially vertically in the end portions 33, 33' of the corrugated sheets 24, 24'. The end zones are the uppermost and lowermost zones 33, 33' of the corrugated sheets 24, 24' that extend from the upper and lower edges of the corrugated sheets 24, 24' by 30%, preferably 25%, and more preferably no more than 20% along the length of the corrugated sheets 24, 24', the length of the corrugated sheets 24, 24' being along the longitudinal direction of the corrugated sheets 24, 24'. Each of the end zones 33, 33' may have peaks 26, 26' and valleys with a different height than the peaks and valleys of the central zone, the central zone being the zone of the layer between the two end zones 33, 33'. Such structures as different heights or bends may be present only in both end zones 33, 33' of the corrugated sheet 24, 24'.

[0077] 3, solid lines depict the corrugation peaks 26 in the face of the corrugated sheet 24 presented towards the viewer, while dashed lines 26' depict the appearance of the corrugation peaks in the corresponding face of the corrugated sheet 24' immediately behind this face. Bending the end portions 33, 33' of the corrugated sheets 24, 24' to extend substantially vertically therein reduces the flow resistance of the end portions 33, 33' of the corrugated sheets 24, 24' compared to the flow resistance of the portions of the corrugated sheets 24, 24' located between the end portions 33, 33'. This leads to a reduced pressure loss in the structured packing element.

[0078] FIG. 4 shows two layers of a structured packing element 12 according to an alternative embodiment. For illustrative purposes, the grid structure of the layers is not shown in FIG. 4 but is shown only in FIG. 6. The structured packing element 12 has a plurality of layers 32, 32', each of which is deformed to provide a plurality of dimples 34, each of which has a dimple valley wall 36. Adjacent layers 32, 32' are arranged parallel to each other so as to contact each other. In other words, adjacent layers 32, 32' are in contact with each other so that at least a portion of the dimple valley wall 36 of the layer 32 contacts the non-recessed surface portion of the adjacent layer 32'. Thus, the dimples 34 actually function as spacers to define channels 30 or open spaces between the layers 32, 32', respectively, that define a maximum distance D between the single layers 32, 32', respectively, for the purpose of allowing the light phase or gas to ascend through the channels 30.

[0079] FIG. 5 shows a structured packing element 12 according to an alternative embodiment. For illustrative purposes, the grid structure of layers is not shown in FIG. 5, but only in FIG. 6. The structured packing element 12 has a number of layers 32, 32', each layer being deformed to define a channel 30 or an open space with two adjacent layers 32, 32' touching each other, and between the layers 32, 32' there is a hexagonal cross section that defines a maximum distance D between the single layers 32, 32' in order to allow the light phase or gas to ascend through the channels 30, respectively. The layers 32, 32' may be arranged in an inclined orientation at alternating angles α to the longitudinal direction so that the channels 30 of the layers 32, 32' cross each other. The preferred gas flow follows these channels 30 alternately to the right and left, while the average gas flow follows the longitudinal direction V.

[0080] 6a to 6f are schematic diagrams of various embodiments of grids 38 forming the layer 32 of structured packing elements 12 according to the present invention, suitable for use in a structured packing element as shown in any of Figs. 2a to 2c, 3, 4 and 5. The grid 38 of the layer 32 of structured packing elements shown in Fig. 6a has openings 40 with a quadrilateral cross section, the openings 40 being surrounded and separated from each other by separating elements 42. The separating elements 42 are narrow strips with an average width b, e.g. 2 mm, which completely surround the openings 40. The two side lengths a1, a2 of the openings 40 are selected to obtain an opening 40 with a suitable hydraulic diameter d, e.g. 3 mm. As known in the art, the hydraulic diameter d can be calculated according to the formula 4A / P, where A is the cross-sectional area of ​​the openings 40 and P is the perimeter of the openings 40.

[0081] According to the invention, the average width b of the separating element 42 between adjacent openings 40 is between 70% and 125% of the average hydraulic diameter d of adjacent openings 40, 40'. Furthermore, the maximum distance D between at least two adjacent layers of the at least two layers 32, 32', measured in a plane perpendicular to the longitudinal direction V, is at least four times greater than the average width b of the separating element 42. By adjusting these relationships, the wetting of the surfaces of the layers 32, 32' of the structured packing element 12 can be further improved, resulting in an increased mass transfer efficiency based on a given volume of the structured packing element 12, despite the fact that the physical area and material are reduced.

[0082] The grid 38 may simply be produced from expanded sheet material, i.e., by cutting and stretching a thin metal plate and then transforming the expanded sheet metal into the desired form, such as a corrugated sheet.

[0083] A grid 38 having openings 40 of various geometries and separating elements 42 of various geometries is shown in Figures 6b to 6f. The openings 40 of the grid 38 in Figures 6b and 6c are quadrilateral, the openings 40 of the grid 38 in Figure 6d are irregular, and the openings 40 of the grid 38 in Figures 6e and 6f are elliptical. They may also be lenticular in shape.

[0084] The determination of the width b of the separating element 42 and the hydraulic diameter d of the opening 40 of the grid 38 of a structured packing element according to the invention is then explained with reference to Figures 7a and 7b. First, a number of plan views of one of the openings 40, 40' of the structured packing element 12 are made by taking three photographic images 44a, 44b, 44c of the opening 40 at different angles. The plan views of the photographic images 44a, 44b, 44c of the opening 40 are along the vertical axis of the plane defined by the adjacent edges 48, 48' of the separating element 42. In this case, the photographic image 44b that maximizes the opening 40 is considered as the plan view of the opening 40. A reference length z is used to determine the length and size on the plan view. This is achieved by identifying or marking a specific length z on a real object in the vicinity of the opening 40 and measuring the length of the opening. The ratio between the effective length z' of this apparent distance on the plan and the distance z measured on the real object is used to scale all other distances measured on the plan.

[0085] To determine the width b of the separating element 42, the separating element 42 in plan view is i In each section, the shortest distance b between adjacent edges 48, 48′ in the section 46 is i is measured. The product d i The sum of bi is d i and multiplied by the factor z / z′ to obtain the average width b of the separation elements 42.

[0086] The hydraulic diameter of the opening 40 is calculated using the formula 4A / P, where A is the cross-sectional area of ​​the opening 40 and P is the perimeter of the same opening 40. The cross-sectional area of ​​the opening 40 is subdivided into j sections 50 (j=1, 2, 3, ... m), each having a simple shape. The area of ​​each section 50 is A j and is calculated using basic measurement standards and basic geometric formulas. j By summing these, the area A of the opening 40 is obtained.

[0087] The perimeter P of the opening 40' is determined by k (k=1, 2, 3, ...K) individual straight lines P that best approximate the opening 40' and represent the opening as a closed polygon. k The perimeter P of the opening 40' is determined by dividing the straight lines P k By summing the lengths of the squares we obtain the perimeter P. Again, these lengths must be converted to actual lengths using the ratio z / z' defined earlier.

[0088] 8 shows the determination of the minimum deformation area of ​​a structured packing element made of corrugated sheets 24, 24' as layers 32, 32'. As mentioned above, in a preferred embodiment of the invention, layers 32, 32' of the structured packing element 12 are made of expanded sheet metal, i.e., by cutting and stretching a thin metal plate and then transforming the expanded sheet metal into, for example, a corrugated sheet 24, 24'. After this processing, the openings and separating elements are likewise warped and / or stretched around the corrugation peaks 26 and valleys 28 of the corrugated sheets 24, 24'.

[0089] However, the inclined planes defined by the approximately straight parts of the grid connecting the peaks 26 and the valleys 28 have openings and separating elements of a size that is not nearly corrected, because the degree of deformation is low at these inclined planes. Therefore, according to the invention, it is preferred to measure the dimensions only at the part of the layer that is not very deformed, designated as the "minimum deformation part" of the corrugated sheet 24, 24'. This "minimum deformation part" is defined as follows: the corrugated sheet has an average layer width W. This average layer width is determined by the amplitude of the majority of the peaks 26 and valleys 28 of the layer 24. In the following, the upper and lower planes represented by the two dashed lines in the figure are drawn so as to touch the majority of the peaks 26 and valleys 28 of the layer. The distance between these two dashed lines is called the average layer width W, which is usually about half the maximum distance D. Very frequently the value W is a constant value, but the value W can vary in the most common cases, in which the two planes do not have to be parallel, and the packing element can include layers of different widths. A third central plane 52 is defined and is positioned so as to equalize the distances measured from each point on this central plane 52 to the upper and lower planes. The minimum deformation part of the corrugated layer 24 to be taken into account when determining the characteristic dimensions of the grid is bounded by the upper and lower limiting planes 54, 54', which are positioned at ±20% of W, more preferably ±30%, and most preferably ±40% of W, centered on the central plane 52. When determining parameters such as the average hydraulic diameter of the holes and the average width of the separating elements, the openings and separating elements within this minimum deformation part are analyzed, i.e. the openings and separating elements found between these two limiting planes 54, 54'. According to one embodiment of the present patent application, for at least 90% of the holes between the limiting planes, the following applies: each opening, together with its surrounding system of separating elements, will have an equal appearance and will have an equal hydraulic diameter d. The surrounding separating elements will have on average the same width b. A layer of structured packing elements that satisfies this statement can be considered as a layer made of a uniform grid.

[0090] The above observations also apply to layers of any different shape, this is not limited to corrugated layers only.

[0091] 9 is a plan view of suitable dimensions illustrating the determination of parameters for a specific example according to the invention, namely for an opening 40 having a diamond shape (i.e., equilateral prism). These dimensions are selected merely for illustrative purposes and are not necessarily general to the invention. Furthermore, it should be noted that there is no intention to make these dimensions fall within an advantageous range of dimensions according to the invention.

[0092] The reference length z is measured and found to be 6.25 mm. By measuring the length z seen in the printed photograph (plan view), z' is obtained. All other lengths that can be measured in the figure are multiplied by the factor z / z' obtained as above. Thus, the longer characteristic length (or, respectively, the diagonal) e1 of the rhombus is 10 mm long and the shorter characteristic length (or, respectively, the diagonal) e2 is 8 mm. The side length a1 of the rhombus is 6.4 mm, which is a1=1 / 2·√(e1 2 +e2 2 The separating element 42 has a width b=1 mm. The area and perimeter P of the opening 40 are given by the following equations: A=e1·e2 / 2 P=4·a1=2·√(e1 2 +e2 2 )

[0093] Therefore, the value is A=40mm. 2 and P = 25.6 mm. The resulting hydraulic diameter is d = 4·A / P = e1·e2 / √(e1 2 +e2 2 ).

[0094] The hydraulic diameter, typically d=6.25 mm, is visualized in FIG. 9 by a circle of diameter d.

[0095] If the grid 38 of structured packing elements is very regularly composed of diamond-shaped openings 40 and isolating elements 42 as shown in FIG. 9, a unit cell U can be defined, which is a typical repeating element of the grid including all its features and dimensions. The unit cell U is a quadrilateral (rectangle) U that covers the opening 40, and the quadrilateral U extends through the midpoints 58 of the four contact points 56 of the isolating elements 42. The unit cell U has a short unit cell height u2 and a long unit cell width u1. The short unit cell height u2 is aligned with the short diagonal e2 of the opening 40, whereas the long unit cell height u1 is aligned with the long diagonal e1 of the opening 40. It is possible to determine the areas within the unit cell U, i.e. the area of ​​the entire unit cell U, the area of ​​the opening 40, and the area of ​​the isolating elements 42. To determine u1 and u2, the lengths e3 and e4 of the small diamonds at the intersection of the two isolating elements 42 must be known. Based on geometric considerations, the following formula is obtained: e3=b √(1+e1 2 / e2 2 ) e4=e3·e2 / e1 u1=e1+e3 u2=e2+e4

[0096] The dimensions obtained are e3 = 1.60 mm, e4 = 1.28 mm, u1 = 11.6 mm, u2 = 9.28 mm. The ratios e2 / e1 and u2 / u1 are equal and therefore their values ​​are 0.8.

[0097] The dimensions of an expanded sheet are usually determined by the unit cell dimensions u1, u2 and the width b of the separating element. Under these circumstances, the hydraulic diameter d can be calculated as follows: e1=u1-b √(1+u1 2 / u2 2 ) e2=e1·u2 / u1 d=e1·e2 / √(e1 2 +e2 2 )

[0098] For simplicity, when dealing with expanded metal sheets with a typical ratio of e2 / e1 less than 0.5, the following approximation may be accurate enough to determine the characteristic lengths e1 and e2 based on u1 and u2: e1=u1-b u1 / u2 e2=u2-b

[0099] In addition, the expanded metal sheet is s This can be characterized by a stretch factor defined as f = u / 2b. In this example, this value is s =4.64.

[0100] The area of ​​the unit cell U is A u =u1 u2 = 107.7 mm 2 The area of ​​the opening in the unit cell U is A o = e1 e2 = 2 A = 80 mm 2 By adding up the areas of the four isolating elements and doubling the area of ​​the small diamond at the intersection of two isolating elements, we obtain the area of ​​the solid part inside the unit cell U: A b =2b√(e1 2 +e1 2 )+e3·e4

[0101] The resulting area is A b =27.66mm 2 The total value is A u =A b +A o is maintained. Within the unit cell U, the ratio of the total area of ​​the openings 40 divided by the total surface area of ​​the layer is A o / A u = 74.3%, which is called the layer porosity. A value close to the porosity can be obtained by using the stretch factor as follows: 1-(1 / f s )=78.5% This represents the raw material savings for a given sheet area when the sheet is stretched.

[0102] The physical area of ​​the unit cell U is A P=A b The sheet area of ​​the unit cell U is A s =A u The geometric area A of the unit cell U is M is twice the seat area, and 2A u (215.4mm 2 In this context, the specific surface area a M is not defined because the shape of the layer is not specified.

[0103] Figure 10 shows a schematic diagram of a cross-section of a packing layer to illustrate how to distinguish between various expressions for the area of ​​a surface. Figure 10a shows a cross-section of a general layer of a structured packing element 12. The material forming the separating elements 42 is represented by the black lines, whereas the white parts represent the openings 40, 40' in the layer 32, 32'. Each black part is a cross-section through a separating element 42. The thickness of the black lines represents the layer material thickness s. In Figures 10b to 10d the area on this layer is represented only by thin lines that follow the contour of the layer. The physical area A of the structured packing layer 32, 32' P is shown in FIG. 10b. This is the sum of the surfaces of all the separating elements 42 measured on one selected side. The edges 48, 48' of the separating elements 42 do not contribute to this area. Rather, A P takes into account only the physically present surface area. Thus, pores do not contribute to this value. The physical area A of the structured packing element 12 P is the physical area A of all layers 32, 32' contained therein P The total value of the sheet area A of the packing layer is shown in Fig. 10c. S This defines the area of ​​the openings in the layer and the physical area A of the layer. P The sheet area A of all layers 32, 32' included in S The sheet area A of the structured packing element 12 is calculated by adding S The geometric area A of the layer is obtained as defined in FIG. 10d on both sides of the layer as if the openings 40, 40′ or holes were not present. M In other words, the sheet area A of the packing layerS By multiplying by 2, we find the geometric area A M can be obtained approximately because both sides of the layer have a geometric area A M This is because the specific surface area a M is the geometric area A of the structured packing element M Let V be the volume occupied by the structured packing elements. M It is defined as dividing by.

[0104] Examples and Comparative Examples The structured packing element 12 shown in FIG. 2 was tested in a distillation column. According to commonly known standard procedures, the pressure drop and mass transfer efficiency across the packing bed are determined using a binary mixture under total reflux conditions. Patent EP 0 995 958 B1 discloses such a test using oxygen and argon at a pressure of 22 psiа. US Patent No. 6,874,769 (B2) discloses the testing of the structured packing element by using the close-boiling binary mixture para-xylene and ortho-xylene. In the present invention, a binary mixture with similar ideal properties, i.e. monochlorobenzene (low boiling solvent) and ethylbenzene (high boiling solvent), was used as this mixture. Other standard ideal binary mixtures of similar boiling points for evaluating the performance of distillation equipment are specified in U. Onken, W. Arlt, "Recommended Test Mixtures for Distillation Columns", 2nd Ed. 1990, The Institution of Chemical Engineers, Rugby, England. ISBN 0-85295-248-1.

[0105] A sufficient amount of the binary mixture was filled at the bottom of the distillation column to maintain a proper liquid level during the operation of the column. The reboiler was started, and a part of the liquid mixture was continuously evaporated, and the vapor rose towards the head of the column. The vapor flow rate can be expressed by a factor F, and is generally determined indirectly through the energy balance of the reboiler or the condenser at the head of the column. The condenser cooled the vapor, so that it condensed back into liquid. Under suitable total reflux conditions, the entire amount of liquid was pumped back to the top of the packing bed, where it was dispersed by a distributor. The distributor is a device with channels for receiving liquid, usually providing a set of evenly spaced orifices, through which the liquid flows slowly downward to reach the top of the packing at the top side of the structured packing bed. After flowing slowly through the structured packing bed, the entire amount of liquid was collected by a collector at the bottom of the column or at the bottom of the bed, from which the liquid was pumped back to the bottom of the column. At the bottom, liquid joined the liquid pool from which liquid again distilled. A constant head pressure p was established by controlling the cooling work of the condenser in combination with a vacuum pump to remove excess inert gas.

[0106] After a period of operation at a constant reboiler work, a steady state condition was achieved. At this point, the pressure drop across the packed bed and the temperature at relevant points along the column were read and top and bottom samples of the mixture were taken from a distributor at the top of the packed bed and from a collector at the lower end of the packed bed or from a sump. While keeping the head pressure constant, multiple operating points were measured by varying the heat exchange rate (and cooling work) affecting the coefficient F (vapor flow) and the associated liquid flow through the packed bed. The same experiment was repeated at multiple head pressure settings.

[0107] The composition of the samples was analyzed by a calibrated gas chromatograph. The top and bottom samples varied by the amount of low boiling solvents they contained. More low boiling solvents, i.e. compounds with lower boiling temperatures, were found in the top sample than in the bottom sample. After the composition of the two components was known, the equation by Fenske (M.R.Fenske, Ind., Engng. Chem. 24, 482, 1932) was applied to determine the number of theoretical plates per meter (NTSM). In some cases, the inverse value HETP, called the height equivalent to a theoretical plate, is used. HETP=1 / NTSM

[0108] A high NTSM (or low HETP) means good mass transfer efficiency.

[0109] The coefficient F is: F=v G √ρ G is defined by v G is the average velocity of the rising steam, which can be determined from the mass flow rate through an energy balance in the reboiler. G is the vapor density at the relevant vapor / liquid equilibrium. Due to pressure and temperature changes along the column, the vapor density and other physical properties of the fluids changed along the column, but relevant information is also available for binary mixtures. Such variables require choosing an appropriate definition of the coefficient F. This can be determined by the properties that prevail under the conditions at the top and bottom of the packed bed. Alternatively, an average value can be calculated taking into account the changes over the entire bed. For comparison purposes, any of the considered approaches is valid, provided that the same approach is used for all tests.

[0110] A large factor F means a high flow rate in the column. The value of F that is achievable is usually limited by flooding, which determines the capacity of the packing. Sometimes the capacity factor c is used instead of F, which is obtained by dividing F by the square root of the density difference between the liquid and the vapor.

[0111] The pressure drop across the packed bed was another relevant result of the experiment. The pressure drop is defined as the difference between the pressure readings at the top and bottom of the packed bed at the bed height H B obtained by dividing by: ΔP / Δz=(p top -p bottom ) / H B

[0112] In the present examples and comparative examples, five different structured packing elements were used, named P1-250, R-250, P2-500, P3-500 and R-500. The structured packing elements P1-250 and P2-500 were corrugated sheet packings made of layers according to the invention, whereas the structured packing elements P3-500, R-250 and R-500 were structured packing elements not according to the invention. More specifically, the structured packing elements R-250 and R-500 were known standard corrugated sheet packings with perforations (leading to a porosity of about 10% in the layers) and surface texturing, as disclosed in GB 1,569,828 and US Patent No. 4,981,621, marketed under the names Mellapak 250.Y and Mellapak 500.X. All structured packing elements had a height of about 200 mm. The relevant parameters of the above mentioned structured packing elements are summarized in Table 1. [Table 1]

[0113] "Example 1 and Comparative Example 1" The structured packing element P1-250 according to the invention and the reference structured packing element R-250 not according to the invention were tested in a distillation column with an internal diameter of 1 m at total reflux with monochlorobenzene and ethylbenzene at head pressures of p=960 mbar (close to atmospheric) and p=100 mbar. The packing bed had a height of 4.3 m. The efficiency curves obtained are shown in Figs. 11 and 12. In both cases, the structured packing element P1-250 according to the invention shown showed a higher mass transfer efficiency (higher NTSM) compared to the reference structured packing element R-250, and also a slightly increased capacity, characterized by the factor F (the efficiency drops sharply). It is noteworthy and surprising that the packing element P1-250 has a mass transfer efficiency of 30% less (20% lower physical area A) than the reference structured packing element R-250. P The structured packing element P1-250 (having

[0114] The pressure drops of both structured packing elements are shown in Figure 13. The pressure drops were very similar. Thus, the structured packing element P1-250 according to the invention had a higher pressure drop at low coefficient F, but with a less steep slope. This gives the new packing a capacity advantage. The P-250 had a lower pressure drop at high flow rates.

[0115] "Example 2 and Comparative Examples 2 to 3" The structured packing element P2-250 according to the invention and the reference structured packing element R-500 were tested in a column with an internal diameter of 0.25 m at total reflux with monochlorobenzene and ethylbenzene at top pressures of p=960 mbar and p=100 mbar. In addition, the structured packing element P3-500 was tested. Although similar to P2-500, the structured packing element P3-500 differed to such an extent that important geometric parameters were set to values ​​outside the numerical ranges specified in the present invention. More specifically, for the structured packing element P3-500, the ratio b / d of the average width of the separating element to the average hydraulic diameter of the adjacent openings was 45%, and the ratio b / s of the average width of the separating element to the layer material thickness was 7. That is to say, both of these ratios are therefore outside the numerical ranges specified in the present invention. The packing beds using P2-500 and P3-500 had a height of 2.4 m, and the packing bed using the standard R-500 had a height of 2.6 m.

[0116] The resulting efficiency curves for these structured packing elements are shown in FIGS. 14 and 15, and the resulting pressure drops for these structured packing elements are shown in FIG.

[0117] The better efficiency of the structured packing element P2-500 according to the invention compared to the structured packing elements P3-500 and R-500 (not according to the invention) at both 960 mbar and 100 mbar head pressures can be easily inferred from Figures 14 and 15. The gap in mass transfer efficiency is particularly visible at low head pressures. Interestingly, P3-500 has a good capacity, but the efficiency is significantly lower than that of R-500. It can also be seen that both structured packing elements P2-500 and P3-500 have a higher pressure drop than R-500 at the initial state, but as F increases, these structured packing elements benefit and both capacities are higher in this graph. [Explanation of symbols]

[0118] 10 Mass transfer columns / distillation columns 12 Structured Packing Elements 14, 14' structured packing element bed 16, 16' dispersion device 18 Retention Device 20 Collection Device 22 Pipe 24, 24' corrugated sheet 26-layer mountain 26' adjacent layer pile 28 Valley 30 channels / free space 32, 32' layer 33, 33' End of corrugated sheet 34 Dimples 36 Dimple Valley Wall 38 Grid 40, 40' Grid Opening 42 Grid Separation Elements 44a, 44b, 44c Photographic images of the opening taken at different angles 46 Separation Element Section 48, 48' Edges of separation element sections 50 Opening Section 52 Median plane 54, 54' upper and lower limiting planes determining the minimum deformation area of ​​the structured packing element made of corrugated layers 56 Contact points of separation elements 58 Midpoint of Contact Points A Cross-sectional area of ​​opening a1 Side length of opening a2 Second side length of opening a M Specific surface area of ​​packing or layer A b Available area of ​​the separation element on one side A j Opening section area A M geometric area A o Area of ​​the opening in the unit cell A P physical area A s Seat area A u Area of ​​the unit cell b Average width of the separating element b i The shortest distance between adjacent edges of the separation element sections d Mean hydraulic diameter of opening d i Separation element section length Longer characteristic length of e1 opening e2 Shorter characteristic length of opening e3 The first length of the diamond at the intersection of two separating elements e4 The second length of the diamond at the intersection of two separating elements g Grid thickness s layer material thickness D the maximum distance between at least two adjacent layers / corrugated sheets P Perimeter of opening P k Straight line of perimeter section of opening U unit cell u1 unit cell width u2 Height of unit cell V Longitudinal, usually vertical W: average layer width of layer or corrugated sheet z Layer reference length z' Reference length on the plan view of the photographic image α Angle of each peak and valley with respect to the longitudinal direction

Claims

1. A structured packing element (12) for a column (10) for mass transfer and / or heat exchange between a heavy fluid phase and a light fluid phase, the structured packing element (12) having at least two layers (32, 32') of a grid (38) having openings (40), the openings (40) being surrounded by and separated from one another by separation elements (42), at least two of the at least two layers (32, 32') being arranged parallel to one another and in contact with one another in a longitudinal direction, such that a free space (30) extending from one end of the at least two layers (32, 32') to an opposite end of the at least two layers (32, 32') is present between the at least two layers (32, 32'). a layer material thickness (s) of at least 50% of said separation element (42) between adjacent openings (40) that is at least 15 times the layer material thickness (s) and is 70% to 125% of the average hydraulic diameter (d) of adjacent openings (40); a maximum distance (D) between at least two of said at least two layers (32.32'), measured in a plane perpendicular to said longitudinal direction, is at least 4 times greater than said average width (b) of said separation element (42); and said average width (b) of said separation element (42) divides said separation element (42) into individual sections i=1, 2, 3, . . . each having a section length di. n, wherein in each of the sections the shortest distance b between adjacent edges in the section is measured and the sum of the products di·bi is divided by the sum of di to obtain the average width b of the separation element (42), and wherein the layer material thickness (s) is the material thickness of the layer (32, 32'), and wherein the layer material thickness (s) is measured at the outer edge of one of the outer edges of the layer (32, 32') by a micrometer screw.

2. 2. The structured packing element (12) of claim 1, wherein the average width (b) of at least 75% of the separation elements (42) between adjacent openings (40) is between 70% and 125% of the average hydraulic diameter (d) of the adjacent openings (40).

3. 3. The structured packing element (12) of claim 1 or 2, wherein the average width (b) of at least 50% of the separating elements (42) between adjacent openings (40) is between 1.5 mm and 4 mm.

4. 4. The structured packing element (12) according to claim 1, wherein at least 50% of the maximum distance (D) between the at least two layers (32, 32'), measured in a plane perpendicular to the longitudinal direction, is between 4 and 15 times greater than the average width (b) of the separating elements (42).

5. 5. The structured packing element (12) of claim 1, wherein in each of the at least two layers (32, 32'), a ratio of a total area of ​​the openings (40) divided by a sheet area (AS) of the layer (32) is between 20% and 38%.

6. 6. The structured packing element (12) of claim 1, wherein at least 50% of the openings (40) of each of the at least two layers (32, 32') have a hydraulic diameter (d) that is between 50% and 150% of the average hydraulic diameter (d) of all the openings (40).

7. 7. The structured packing element (12) of claim 6, wherein the hydraulic diameter (d) of at least 50% of the openings (40) of each of the at least two layers (32, 32') is between 1.25 mm and 5 mm.

8. At least 50% of the openings (40) have a rectangular or quadrilateral cross section and the shorter characteristic length (e ２ ) is 1 mm to 4 mm, and the longer characteristic length (e １ 8. The structured packing element (12) according to claim 1, wherein the average width (b) of the separating elements (42) between adjacent rectangles is between 2 mm and 8 mm and the average width (b) of the separating elements (42) between adjacent rectangles is between 1.5 mm and 4 mm.

9. At least 50% of the openings (40) have a rectangular or quadrilateral cross section and the shorter characteristic length (e ２ ) to the longer characteristic length (e １ 9. The structured packing element (12) of claim 1, wherein the ratio of the thickness of the packing element (12) divided by the thickness of the packing element (12) is between 0.4 and 0.

7.

10. 10. The structured packing element (12) of claim 1, wherein a maximum distance D between each of the at least two layers (32, 32'), measured in a plane perpendicular to the longitudinal direction, is at most 15 times greater than the average hydraulic diameter (d) of the openings (40).

11. 11. The structured packing element (12) according to claim 1, wherein at least 50% of the at least two layers (32, 32') have periodic deformation portions (26, 28, 34), and an open space (30) between the at least two layers (32, 32') is defined by the periodic deformation portions (26, 28, 34).

12. 12. The structured packing element (12) of claim 11, wherein the periodic deformations (26, 28, 34) are corrugated with a plurality of alternatingly oriented peaks (26) and valleys (28), the peaks (26) of one layer (32, 32') contacting the valleys (28) of an adjacent layer (32, 32') and the valleys (28) of one layer (32, 32') contacting the peaks (26) of an adjacent layer (32, 32'), and the adjacent layers (32, 32') are oriented such that the peaks (26) and valleys (28) of the adjacent layers (32, 32') crisscross with the peaks (26) and valleys (28) of the layers (32, 32') that extend obliquely with respect to the longitudinal direction (V).

13. A mass transfer column comprising at least one structured packing element (12) according to any one of claims 1 to 12.

14. 14. Use of a structured packing element (12) according to any one of claims 1 to 13 for mass transfer and / or heat exchange.

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