Structural cross-channel packing elements with reduced material requirements.

Abstract

The present invention relates to a structural cross-channel packing element for a column for mass transfer and / or heat exchange between a heavy fluid phase and a light fluid phase, the structural cross-channel packing element having at least two adjacent layers made of expanded metal sheets each having openings, the openings being surrounded by and separated from one another by separating elements, at least two of the at least two layers being arranged parallel to and in contact with one another in the longitudinal direction of the packing element, so that an open space is provided between the at least two layers, the open space extending from one end of the at least two layers to the opposite end of the at least two layers. and wherein the ratio between the average width of at least 50% of the separating elements between adjacent openings and the sheet material thickness is at least 15, the ratio between the maximum distance between at least two of the at least two layers measured in a plane perpendicular to the longitudinal direction and the average width of the separating element is at least 4, and the ratio between the distance between two openings adjacent to a separating element in a direction perpendicular to the stretching direction of the expanded metal sheet and the average width of this separating element is 4 to 6 for at least 50% of all separating elements.

Description

[Technical field]

[0001] The present invention relates to a structural cross-channel packing element for a column for mass transfer and / or heat exchange between a heavy fluid phase and a light fluid phase. [Background technology]

[0002] Structured packing elements are used in mass transfer columns, e.g. fractionation, distillation, absorption, extraction or flue gas scrubbers. Structured packing elements function to improve mass and / or heat transfer between at least two fluid phases of different densities, and they usually operate in countercurrent flow. In distillation and absorption applications, the light phase is gas or vapor and the heavy phase is condensate or liquid, whereas in extraction processes, both phases are liquids with different densities. Structured packing elements have several different layers, each of which provides a surface area for the heavier phase. The heavier phase trickles down and diffuses along the surface of the layer. 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, which is simultaneously 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 packing element, and therefore opposite to the average flow direction of the heavier phase. By allowing one heavy phase to spread over the surface of the 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, 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 open space in the collector for the light phase to ascend.

[0004] A common type of structural packing element is the so-called cross-channel corrugated sheel packing, which is assembled, for example, from a number of corrugated sheets, which are parallel to each other and in contact with each other. Typically, corrugated metal sheets are fixed to each other by a number of rods that penetrate the corrugated sheets perpendicular to their longitudinal sections, 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 a number of periodic deformations, such as alternating peaks and valleys, 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 effect on the flow of the gas and liquid phases in the packing and promote mass transfer between the phases. That is, the gas and liquid phases are brought into contact in the channels of the structural packing element, 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 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 taking place. 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 layer of packing elements that is wetted by the liquid. Cross-channel corrugated packings made of wire mesh are known to have good wettability, thanks to the good diffusion of the heavy phase on the surface of the corrugated sheets by the capillary forces of the wire mesh, and therefore high mass transfer efficiency (due to this good wettability). 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 EP 1 477 224 A1. 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 corrugated, relatively precisely structured perforated metal sheets is lower than that of wire mesh-based packings, 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 failure 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 structural packing elements, it has already been proposed in DE 3818917 C1 and CN 88200252 U to provide cross-channel corrugated packing made of a perforated layer with a high porosity (i.e. a large quotient 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 structural 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 structural packing element made of an open metal sheet with a very high porosity, of the order of 50% or more. CN88200252U discloses a structural 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 open area on the sheet, i.e., the porosity, is 40% to 50%. Thus, both of these prior art documents teach providing a structural packing element with a sheet layer having a very high porosity, which is more than 40%, preferably about 50%. In contrast to these, conventional structural packing elements have a very low porosity of only about 10% at most.

[0008] Structural packing elements based on different principles than cross-channel corrugated packing are disclosed, for example, in EP 0069241 A1, US Pat. No. 4,304,738, and EP 0250061 A1. The layers of these structural packing elements are constructed from expanded sheet metal, which is stretched to a specific layer width. However, unlike cross-channel corrugated packing, the layers of these structural packing elements are not corrugated and do not deform, except for the deformations associated with the stretching process. This limits the open space for ascending vapor. Thus, mass transfer efficiency is not optimal. This is because the open 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 structural packing element. It is desirable to impose on the vapor 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 hPa (10 mbar) per meter of packing height.

[0010] It is optimal for a packing element to have a good mass transfer efficiency as well as a 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 for the investment costs of the mass transfer column to be minimized. However, these two properties depend on opposite trends with respect to the specific area and other geometric parameters. More specifically, a large specific area, i.e. a large quotient of the geometrical area of ​​the packing element divided by the volume occupied by it, leads to a high degree of contact between the light and heavy phases. This is because each packing element has a high mass transfer efficiency, usually expressed as the number of theoretical plates (NTSM) per meter of packing height. However, packing elements with a large specific area are characterized by a high flow resistance for the light phase, since each 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 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] EP0190435B1 [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 structural packing element that has a higher mass transfer efficiency at a given volume, or has a larger volume at a given mass transfer efficiency, or has 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 structural cross-channel packing element for a column for mass transfer and / or heat exchange between a heavy and a light fluid phase, the structural cross-channel packing element having at least two adjacent layers made of expanded metal sheets each having 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 of the packing element, such that an open space is provided between these at least two layers, extending from one end of the at least two layers to the opposite end, such that at least one of the heavy and light fluid phases can flow therethrough, the ratio between the average width of at least one of the separation elements between adjacent openings, and preferably at least 50%, and between the sheet material thickness of the maximum distance between at least two of the at least two layers, measured in a plane perpendicular to the longitudinal direction, and the average width of the separation elements is at least 15, is at least 4, and the ratio between the distance between two openings adjacent to a separating element in a direction perpendicular to the stretch direction of the expanded metal sheet and the average width of this separating element is preferably between 4 and 6 for at least 50% of all separating elements, the distance between the two openings being measured by determining the distance between the outermost point on one side of an edge of one of the openings in a direction perpendicular to the stretch direction of the expanded metal sheet and the outermost point on the same side of an edge of an adjacent opening in the same direction of the expanded metal sheet, the longitudinal direction of the filler element being as defined herein, and the stretch direction of the expanded metal sheet being in a direction perpendicular to the longitudinal direction of the structural cross channel filler element, the average width of the separating element being determined by dividing the separating element into individual sections i=1, 2, 3, ... n, each having a section length di, and in each of these sections the shortest distance bi between adjacent edges within the section is measured and the sum of the products di·bi is divided by the sum of the products di to obtain the average width b of the separating element.

[0015] This solution is based on the surprising discovery that mass transfer efficiency at a given volume can be significantly improved if the average width of the separating element between adjacent openings is large relative to the openings (i.e. the ratio between the distance between two openings perpendicular to the stretch direction of the expanded metal sheet adjacent to the separating element (perpendicular to the longitudinal direction) and the average width of this separating element is between 4 and 6) and even significantly wider than the sheet material thickness (i.e. 15 times or more).

[0016] This was particularly unexpected, since it contradicts the teachings of DE 3818917 C1 and CN 88200252 U, two prior art documents which imply that a free film suspended between the separating elements contributes twice to the mass transfer area, and therefore further propose to minimize the width of the separating elements and to remove an additional portion of the physical area. In view of this, it becomes even more surprising that by adjusting the above mentioned parameters as described above, the mass transfer efficiency at a given volume is significantly improved.

[0017] Another significant advantage of the structural packing element according to the invention is that it is not based on the use of any expensive layer material. Rather, these layers are simply produced from expanded metal sheets, i.e. by cutting and stretching thin metal plates and transforming the expanded metal sheets in a second step, for example into corrugated sheets. Thus, a cost-efficient raw material is used, the material requirements of which are further reduced by stretching the raw material. Overall, the invention provides a cost-efficient and versatile structural cross-channel packing element with a higher mass transfer efficiency at a given volume or a larger capacity at a given mass transfer efficiency, respectively.

[0018] The longitudinal direction of the structural cross-channel packing element is the direction from the top area to the bottom area of ​​the structural cross-channel 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 structural cross-channel packing element and the mass transfer and / or heat exchange column, respectively. More specifically, the longitudinal direction of the structural cross-channel packing element can be determined as follows: the structural cross-channel packing element is arranged on a horizontal area, such that layers of the structural cross-channel packing elements arranged parallel to each other and in contact with each other extend in the vertical direction, and further such that 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 structural cross-channel packing element. Thus, the longitudinal direction is the direction from the top to the bottom of a structural cross-channel packing element so arranged, or in other words: a heavy phase, e.g. water, that falls onto the top of a structural cross-channel 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.

[0019] 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 open space between two layers is obtained by the layer width W. The maximum distance D between two adjacent layers of a structural 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 structural filling 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.

[0020] According to the invention, the structural filling element has at least two layers arranged parallel to each other in the longitudinal direction, the parallel arrangement of the two layers means, according to the invention, that one of the layers is inclined with respect 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 has no inclination with respect to the other layer.

[0021] Furthermore, according to the invention, at least 50% of the separating elements between adjacent openings have a ratio between the average width and the sheet material thickness of at least 15. This means that for at least 50% of the separating elements, the ratio between the average width and the sheet material thickness of the respective separating element 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.

[0022] The sheet material thickness means the thickness of the material constituting or forming the layer, respectively. Since according to the invention the layer is made by an expanded metal sheet, the sheet material thickness is the sheet thickness. If the sheet thickness varies over the area of ​​the layer, the sheet material thickness is the sheet thickness measured at one of the outer edges of the sheet material thickness, 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.

[0023] 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. 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.

[0024] Advantageously, the average width b of the separating element is determined on a top view or plan view of one of the openings adjacent to the separating element. This is advantageously achieved by taking a photographic picture of the opening. The top view of the opening is made by placing the expanded metal sheet on a flat surface and making a photographic picture of the opening after flattening each expanded metal sheet by placing a plate on top of the expanded metal sheet and pressing the plate downwards with a pressure small enough only to flatten the expanded metal sheet to remove periodic deformations without changing the geometry and dimensions of the separating element and the openings, i.e. without changing the geometry and dimensions of the grid structure of the expanded metal sheet. The plan view of the opening is made on the expanded metal sheet in its configuration when used in the structural cross-channel filler element, i.e. without flattening or otherwise mechanically processing the expanded metal sheet. More specifically, 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, trial and error will yield the most appropriate view. Multiple photographs are taken, such as at least 5 photographs or preferably at least 10 photographs, from various angles. In this case, the photograph that maximizes the opening is considered the plan view of the opening. One reference length z can be used to determine the length and size on the plan view and also on the top view. This is best achieved by identifying or marking a specific length z on the actual 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 respective plan view or top view and the distance z measured on the actual object is used. For example, if the actual length of the segment width is b i =b i '·(z / z'), where the variables with primes denote lengths measured in plan or top view, respectively, and the variables without primes denote actual lengths.

[0025] 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 measures (shape length and height) and basic geometric formulas (known from Euclidean geometry). Preferably, the area is determined on a top or 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.

[0026] The perimeter of an opening of simple shape can be determined using basic criteria of measurement and basic geometric formulas. In the most common case, a top or 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.

[0027] Numeric 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.

[0028] Further details regarding the measurement methods and illustrative examples are given further below in conjunction with the figures.

[0029] According to the invention, the layers of structural cross-channel filling elements are made of expanded metal sheets, which are produced by stretching, i.e. by cutting and stretching the sheet metal. The resulting openings are therefore generally substantially elliptical, lenticular, trapezoidal or rhomboidal, usually substantially lenticular or trapezoidal in shape. Thus, as shown diagrammatically in the figures and as will be explained in more detail later, each expanded metal sheet is in fact a grid with openings, each of which is surrounded by a separating element having a width b, the separating elements of adjacent openings being connected to each other at contact points. The hydraulic diameter is generally unknown, but can be determined as described above or calculated from commonly used characteristic dimensions as will be explained later. Expanded sheets are usually characterized by the dimensions of their openings and the (average) width of the separating elements b. Thus, the openings, which are usually shaped substantially lenticular or trapezoidal, have a shorter and a longer characteristic length, the shorter characteristic length of the opening (hereinafter also referred to as "e2" or abbreviated as "e2") being the maximum dimension of the opening in the stretch direction of the expanded metal sheet, and the longer characteristic length of the opening (hereinafter also referred to as "e1" or abbreviated as "e1") being the maximum dimension of the opening in the direction perpendicular to the stretch direction of the expanded metal sheet. The stretch direction of the expanded metal sheet is the direction along which the sheet metal is stretched during the production of the expanded metal sheet. More specifically, the stretch direction is according to the invention the direction perpendicular to the longitudinal direction of the structural cross-channel filler element. The direction perpendicular to the stretch direction is therefore the longitudinal direction of the structural cross-channel filler element. The (average) width b of the separating element b and the characteristic length of the opening determine the distance between adjacent openings. The distance between adjacent openings in the direction of expansion of the expanded metal sheet is different from the distance between adjacent openings in a direction perpendicular to the direction of expansion of the expanded metal sheet.Hereinafter, the distance between a first opening and a second opening adjacent to each other in the stretching direction of the expanded metal sheet is also referred to as u2, i.e. abbreviated as u2. In contrast, the distance between a first opening and a third opening adjacent to the first opening in a direction perpendicular to the stretching direction of the expanded metal sheet is also referred to as u1, i.e. abbreviated as u1. These distances u1 and u2 may be measured as will be explained in detail later with reference to the figures. In case the openings are approximately diamond shaped, the following equation may be used to determine the hydraulic diameter (hereinafter also referred to as "d", i.e. abbreviated as "d") of each opening: e1=u1-b√(1+u1 2 / u2 2 ) e2=e1·u2 / u1 d=e1·e2 / √(e1 2 +e2 2 )

[0030] 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

[0031] Additionally, expanded metal sheets may be characterized by a stretching factor, defined as u2 / 2b. The inverse of this stretching 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 given further below in conjunction with the figures.

[0032] According to the invention, the packing elements are structural cross-channel packing elements, so 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 at least two layers are made of expanded metal sheets and have periodic deformations, the layers being oriented so that the periodic deformations of the adjacent layers cross the periodic deformations of the layers extending obliquely to the longitudinal direction in a crisscrossing manner, 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 each of the layers contact each of the adjacent layers at the crossing points between the periodic deformations of the layer and the deformations of the adjacent corrugated layer, and the open spaces between the at least two layers are defined by the periodic deformations. Preferably, the distance between the uppermost points of two adjacent periodic deformations of the layer is between 10 mm and 25 mm, more preferably between 13 mm and 23 mm, depending on the surface area.

[0033] In particular, good results are achieved if the expansion factor of the at least two layers of expanded metal sheet is between 1.1 and 1.5, more preferably between 1.2 and 1.35.

[0034] According to the invention, the distance u1 is measured by determining the distance between the outermost point on one side of the edge of one of the openings in a direction perpendicular to the stretch direction of the expanded metal sheet and the outermost point on the same side of the edge of the adjacent opening in the same direction of the expanded metal sheet. For example, if a photographic image of a top view or plan view of a layer of structural cross-channel filler elements is made (with the stretch direction shown in the vertical direction of the photographic image and the direction perpendicular to the stretch direction shown in the horizontal direction of the photographic image), the distance u1 can be determined as the distance between the outermost point on the left side of the edge of an opening and the outermost point on the left side of the edge of the opening adjacent to this opening in the same direction of the expanded metal sheet.

[0035] To determine the distance u1 particularly accurately, the distance between the outermost point on one side of the edge of an opening in a direction perpendicular to the stretching direction of the expanded metal sheet and the outermost point on the same side of the edge of the fifth or nth adjacent opening located relative to this opening in a direction perpendicular to the stretching direction of the expanded metal sheet can be measured and divided by 4 or (n-1).

[0036] More preferably, the distance u1 is determined by measuring the distance between the outermost point on one side of an edge of an opening in a direction perpendicular to the stretching direction of the expanded metal sheet and the outermost point on the same side of an edge of a tenth adjacent opening that is disposed relative to this opening in a direction perpendicular to the stretching direction of the expanded metal sheet, and dividing by 9.

[0037] According to the invention, the ratio between the distance u1 between two openings adjacent to a separating element in the direction perpendicular to the stretching direction of the expanded metal sheet and the average width of this separating element is, for at least 50% of all separating elements, between 4 and 6. In particular, good determination is achieved if the ratio between the distance u1 and the average width b of 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 4 and 6, preferably between 4.5 and 5.5, more preferably between 4.9 and 5.1.

[0038] In a further development of the inventive idea, the distance u1 is preferably between 5 mm and 20 mm in 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 at all openings. More preferably, the distance u1 is between 7.5 mm and 15 mm, and most preferably between 9 mm and 11 mm in 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 at all openings.

[0039] According to another particular embodiment of the invention, the ratio between the distance u2 between a first opening and a second opening adjacent to each other in the stretching direction of the expanded metal sheet and the distance u1 between a first opening and a third opening adjacent to each other in a direction perpendicular to the stretching direction of the expanded metal sheet is between 0.4 and 0.7, and the distance u2 is measured by determining the distance between the outermost point on one side of an edge of a first opening in the stretching direction of the expanded metal sheet and the outermost point on the same side of an edge of an adjacent second opening adjacent to each other in the stretching direction of the expanded metal sheet, and the distance u1 is measured as described above.

[0040] As with determining distance u1, distance u2 is preferably measured by determining the distance between the outermost point on one side of the edge of a first opening in the stretching direction of the expanded metal sheet and the outermost point on the same side of the edge of a fifth or even tenth (nth) adjacent opening which is positioned relative to this opening in the stretching direction of the expanded metal sheet, and dividing this distance by 4 or 9 (n-1), respectively.

[0041] In particular, good results are achieved when the ratio between the distance u2 and the distance u1 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 at all openings, between 0.4 and 0.7, more preferably between 0.45 and 0.70, and most preferably between 0.49 and 0.55.

[0042] Additionally, it is preferred that the distance u2 is between 2mm and 8mm, more preferably between 3mm and 7mm, and most preferably between 4mm and 6mm in 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 at all openings.

[0043] According to another particular embodiment of the invention, the average width b of at least one separating element between adjacent openings is between 70% and 125% of the average hydraulic diameter d of the adjacent openings.

[0044] In a further development of the inventive idea, it is proposed 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%, and most preferably of all 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%, preferably at least 75%, more preferably at least 80%, even more preferably at least 90%, even more preferably at least 95%, and most preferably of all separating elements is between 75% and 100% of the average hydraulic diameter d of the adjacent openings.

[0045] 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.

[0046] According to the invention, the ratio between the average width b of at least 50% of the separating elements between adjacent openings and the layer material thickness (hereinafter also referred to as "s" or abbreviated to "s") is at least 15. Particularly good determination is obtained if the ratio between the average width b of at least 50% of the separating elements between adjacent openings and the layer material thickness is at least 18. Preferably, the ratio between the average width and the sheet material thickness of at least 75%, more preferably 80%, even more preferably at least 90%, even more preferably at least 95%, most preferably all of the separating elements between adjacent openings is at least 18.

[0047] According to the invention, 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 the separating elements is at least 4. 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.

[0048] Particularly good results are obtained when the ratio between the maximum distance measured in a plane perpendicular to the longitudinal direction and 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 at least two layers is at least 4.

[0049] It is further preferred that the ratio between the maximum distance D between at least two layers and the average width b of the separating elements in 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 them, measured in a plane perpendicular to the longitudinal direction, is at least 5, more preferably at least 8.

[0050] In a further development of the inventive idea, it is proposed that the ratio between the maximum distance D between at least two layers, measured in a plane perpendicular to the longitudinal direction, 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, and the average width b of the separating elements is between 4 and 15, preferably between 5 and 13, and most preferably between 8 and 12.

[0051] In particular, good results are obtained if 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 between 8 mm and 80 mm, preferably between 12 mm and 51 mm, and most preferably between 16 mm and 30 mm. It is therefore preferred that the layer width W is between 4 mm and 40 mm, more preferably between 6 mm and 25.5 mm, and most preferably between 8 mm and 15 mm.

[0052] According to a particularly preferred embodiment of the invention, in at least one of the at least two layers, the quotient 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 areas of all the separating elements, measured on one side only, and the total area of ​​the openings enclosed by the separating elements. The sum of the openings is simply the sum of the areas (cross-sectional areas) A of the openings. Furthermore, the sheet area A of the structural filling elements is S is the total sheet area of ​​the layers contained in the structural packing element. As mentioned above, the porosity of a packing layer is the quotient of the total area of ​​the openings in this layer divided by the sheet area of ​​this layer.

[0053] 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.

[0054] Furthermore, it is preferred that the porosity of 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 is between 25% and 35%, most preferably between 28% and 32%, which leads to a particularly good wetting of the layers of the structural packing element according to the invention.

[0055] Particularly good results are obtained if the grid structure of the expanded metal sheet is uniform, i.e. if all or at least the majority of the openings and separating elements are equal or at least to a high degree 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%, most preferably between 90% and 110% of the average hydraulic diameter of all openings.

[0056] 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.

[0057] 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 shorter characteristic length e2 of 1.0 mm to 4.0 mm, preferably 2.0 mm to 3.0 mm, and a longer characteristic length e1 of 2.0 mm to 8.0 mm, preferably 2.5 mm to 7.0 mm, and most preferably 3.0 mm to 6.0 mm. As mentioned above, the shorter characteristic length e2 of an opening is the maximum dimension of the opening in the stretch direction of the expanded metal sheet, and the longer characteristic length e1 of an opening is the maximum dimension of the opening in the direction perpendicular to the stretch direction of the expanded metal sheet.

[0058] In a further development of the inventive idea, it is proposed that the ratio between the shorter characteristic length e2 of an opening and the longer characteristic length e1 of the same opening 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%, most preferably in all cases between 0.4 and 0.7, preferably between 0.45 and 0.6, most preferably between 0.49 and 0.55, of the openings. As mentioned above, the shorter characteristic length e2 of an opening is the maximum dimension of the opening in the stretch direction of the expanded metal sheet, and the longer characteristic length e1 of an opening is the maximum dimension of the opening in the direction perpendicular to the stretch direction of the expanded metal sheet.

[0059] The present invention is not particularly limited with respect to the material of the expanded metal sheets of the structural filler elements, for example, the expanded metal sheets may be made of stainless steel or a composite selected from the group consisting of aluminum, copper, titanium, zirconium, and alloys.

[0060] Preferably, each expanded metal sheet has a sheet material thickness s of 0.05 to 0.50 mm, more preferably 0.08 to 0.20 mm, and most preferably 0.09 to 0.15 mm.

[0061] Typically, 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 the layer of structural packing elements have a substantially elliptical, lenticular, or trapezoidal cross-section.

[0062] After production, i.e. after cutting and stretching of the metal plate, the resulting expanded metal sheet 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 result from the drilling process and thus contribute to the thickness. The resulting dimension of the expanded metal sheet is called the grid thickness (hereinafter also referred to as "g" or abbreviated to "g") and can be equal to the layer material thickness (this is the case when the expanded metal 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 the width b. Thus, 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.

[0063] More preferably, the ratio between the average grid thickness g and the sheet material thickness s of each layer is at least 6.

[0064] In particular, good results are achieved when the average grid thickness g of each layer (32, 32') is between 1.0 mm and 1.4 mm, preferably between 1.1 mm and 1.3 mm, and more preferably between 1.15 mm and 1.25 mm.

[0065] The grid can also be flattened by pressing a plate onto the top of the grid as described above.

[0066] Another embodiment of the invention includes rolling an expanded metal sheet to provide it with a textured surface. More specifically, each of the periodic deformations, particularly corrugations, can have a trickle surface with a patterned front surface including a plurality of protrusions and recesses that define continuously intersecting capillary channels. The protrusions can be arranged to abut adjacent protrusions, can have channel-defining sidewalls therebetween, and can have a patterned back surface equal to the front surface, defining continuously intersecting capillary channels, as disclosed, for example, in EP0190435B1. The protrusions can have a height in the range of the grid thickness g without any further processing.

[0067] Preferably, the ratio of maximum distance D to grid thickness g (ie, D / g) is at least three.

[0068] In particular, good results are obtained when the ratio between the maximum distance D between each adjacent layer of the at least two layers, measured in a plane perpendicular to the longitudinal direction, and the average hydraulic diameter d of the opening is at most 15.

[0069] The expanded metal sheet provides a rough side and a smooth side, as shown in Figure 7c. Preferably, the single layers of structural cross channel filler elements are arranged such that adjacent layers are arranged with their rough side on top of their rough side, and such that adjacent layers are arranged with their smooth side on top of their smooth side.

[0070] In a further development of the idea of ​​the present invention, it is proposed 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 at least two layers have periodic deformations, and the open space between at least two layers is defined by these periodic deformations. It is particularly preferred that all layers of the structural packing element of the present invention have such periodic deformations, i.e. that the structural packing element of the present invention does not have any flat layers. Preferably, the angle of each periodic deformation (hereinafter also referred to as "α", i.e. abbreviated to "α") with respect to the longitudinal direction is between 10° and 60°, more preferably between 20° and 50°, and most preferably between 25° and 47°, and the periodic deformations of adjacent layers are preferably oriented in opposite directions.

[0071] 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 the adjacent layers being oriented such that the peaks and valleys of the adjacent layers are crisscrossed with the peaks and valleys of the layers extending diagonally to the longitudinal direction. Thus, preferably 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 at least two layers have a periodic deformation portion, and the periodic deformation portion of the cross-package element is 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 the adjacent layers being oriented such that the peaks and valleys of the adjacent layers are crisscrossed with the peaks and valleys of the layers extending diagonally to the longitudinal direction. Of course, not all peaks of a layer will contact one or more valleys of an adjacent layer, and it is possible that some of the peaks of a layer will contact one or more valleys of an adjacent layer, or 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 those 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.

[0072] 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 structural packing element in at least one direction of the cross section. This angle should not be too large in order to minimize pressure drop and maximize capacity.

[0073] In order to reduce the pressure loss of the structural packing element, in a further development of the idea of ​​the invention 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 structural 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 so 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.

[0074] 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.

[0075] 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, which allows a uniform distribution of the light phase in at least one direction of the cross section of the structural packing element.

[0076] 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 area a required for mass transfer. M It is determined by: If a larger surface is required, i.e. the specific area increases, there will be more layers and the maximum diameter D will decrease accordingly. The structural packing elements are roughly cylindrical with a circular cross section, but depending on the shape of the heat exchange and / or mass transfer column, other shapes of cross section may be present, for example rectangular shapes. If the column has a large diameter, the elements are generally subdivided into several segments or tiles to reduce the weight and to allow piecemeal mounting.

[0077] The structural filling element according to the invention is 60 m 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 area a M A particularly good combination of mass transfer efficiency and capacity is obtained when

[0078] Specific area a M is the volume occupied by the structural filling element V M The geometric area A of the structural packing element divided by M The geometric area A of the structural packing element is defined as M is 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.

[0079] 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 S A P takes into account only the physically present surface. Holes or openings do not contribute to this value. The sheet area A of the structural filling element S is obtained by adding up the sheet areas of all the layers contained therein.

[0080] Physical area A of the structured packing layer P is the sum of the surfaces of all separating elements in the layer of structured packing, measured on one selected side. The edges of the layer material thickness s do not contribute to this area. The physical area of ​​the packing A P is the total physical area of ​​all layers contained therein.

[0081] 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.

[0082] Preferably the structural filler element has a height of between 100mm and 300mm, preferably between 150mm and 250mm.

[0083] According to another aspect, the present invention relates to a mass transfer column having at least one structured packing element as described above.

[0084] 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°.

[0085] In addition, preferably the mass transfer column comprises 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 beds of structured packing elements during operation of the mass transfer column.

[0086] 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 packing elements, the collector making it possible to collect the heavy phase slowly flowing down the surface of the layer of packing elements during operation of the mass transfer column.

[0087] 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]

[0088] [Figure 1] FIG. 1 is a schematic side view illustrating a mass transfer column having a plurality of structural cross-channel 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 structural cross-channel filler element according to one embodiment of the present invention. [Figure 2b] FIG. 2b is a schematic side view showing the structural cross-channel packing element shown in FIG. 2a. [Figure 2c] FIG. 2b shows two layers of the structural cross-channel packing element shown in FIG. 2a. [Diagram 3]11A-11C are partial views of a structural cross-channel packing element according to another embodiment of the present invention. [Figure 4a] 1A-1D are schematic diagrams showing various embodiments of expanded metal sheet grid structures for layers of structural cross channel filler elements according to the present invention. [Figure 4b] 1A-1D are schematic diagrams showing various embodiments of expanded metal sheet grid structures for layers of structural cross channel filler elements according to the present invention. [Figure 4c] 1A-1D are schematic diagrams showing various embodiments of expanded metal sheet grid structures for layers of structural cross channel filler elements according to the present invention. [Figure 4d] 1A-1D are schematic diagrams showing various embodiments of expanded metal sheet grid structures for layers of structural cross channel filler elements according to the present invention. [Figure 4e] 1A-1D are schematic diagrams showing various embodiments of expanded metal sheet grid structures for layers of structural cross channel filler elements according to the present invention. [Figure 4f] 1A-1D are schematic diagrams showing various embodiments of expanded metal sheet grid structures for layers of structural cross channel filler elements according to the present invention. [Figure 5a] 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 5b] 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 6] FIG. 13 illustrates the determination of the area of ​​minimum deformation of a structural cross-channel packing element made of corrugated layers. [Figure 7a] FIG. 13 is a schematic top view showing an expanded metal sheet of a layer of structural cross channel filler element according to another embodiment of the present invention. [Figure 7b] FIG. 7b is a schematic view along plane A of FIG. 7a. [Figure 7c] FIG. 7b is a schematic view along plane B of FIG. 7a. [Figure 8] FIG. 8 is a schematic plan view showing an expanded metal sheet of a layer of the structural cross-channel filler element shown in FIG. [Figure 9] 9A-9D are schematic diagrams showing cross sections of a packing bed to illustrate the definitions of areas AP (FIG. 9b), AS (FIG. 9c), AM, VM and aM (FIG. 9d). [Figure 10] 1 is a graph showing the efficiency curves obtained in Example 1 and Comparative Example 1 at a distillation column top pressure of 960 hPa (960 mbar). [Figure 11] 1 is a graph showing the efficiency curves obtained in Example 1 and Comparative Example 1 at a top pressure of the distillation column of 100 hPa (100 mbar). [Figure 12] 1 is a graph showing the pressure drop obtained in Example 1 and Comparative Example 1 at a distillation column top pressure of 100 hPa (100 mbar). [Figure 13] 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 hPa (960 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 100 hPa (100 mbar). [Figure 15] 1 is a graph showing the pressure drop obtained in Example 2 and Comparative Examples 2 and 3 at a distillation column top pressure of 100 hPa (100 mbar). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0089] 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 present 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. 4. The distillation column 10 has a plurality of structural cross-channel 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 open space in the collector for the vapor to ascend.

[0090] 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 the structural cross-channel packing elements 12. Open spaces are provided between the different layers of the structural cross-channel packing elements 12, and these open spaces are filled with gas, providing a path for the ascending gas while the gas is moved by the pressure gradient. By allowing the liquid to spread on the surface of the layers of the structural cross-channel 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'.

[0091] Figures 2a to 2c show a structural cross-channel packing element 12 of the type of so-called cross-channel corrugated packing. For the sake of illustration, the grid structure of the layers is not shown in Figure 2, but only in Figure 4. The structural cross-channel packing element 12 is assembled from a number of corrugated sheets 24, 24', which are parallel to each other and in contact with each other. 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 4. 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, all of the corrugated sheets 24, 24' actually consist of such a grid. This is not shown in Figures 2a to 2c for illustrative reasons 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'.

[0092] 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 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 structural cross-channel 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 structural cross-channel 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 downward through the mass transfer column. Overall, the light phase flows through the open spaces or channels 30, respectively, and there is no bypass flow through the openings 40 in the grids 38 of the layers 32, 32' of the structural cross-channel packing element 12. This leads to a particularly efficient mass and energy transfer between the light and heavy phases. Furthermore, the crisscross manner of the channels 30 leads to an optimal distribution of the layers from left to right.

[0093] Figure 3 shows a partial view of a structural cross-channel filler element according to an alternative embodiment. The structural cross-channel filler element of Figure 3 is similar to the structural cross-channel filler 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 portions 33, 33' and therefore extend substantially vertically in the end portions 33, 33' of the corrugated sheets 24, 24'. In Figure 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' just behind this face. By bending the end portions or zones 33, 33' of the corrugated sheets 24, 24' to extend substantially vertically within the end portions 33, 33', respectively, the flow resistance of the end portions 33, 33' of the corrugated sheets 24, 24' is reduced compared to the flow resistance of the portions of the corrugated sheets 24, 24' located between the end portions 33, 33'. This leads to reduced pressure losses in the structural cross-channel packing element. 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%, 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'.

[0094] 4a to 4f are schematic diagrams of various embodiments of grids 38 forming the layer 32 of the structural cross-channel packing element 12 according to the present invention, suitable for use in a structural cross-channel packing element as shown in any of the figures 2a to 2c and 3. The grid 38 of the layer 32 of the structural cross-channel packing element shown in figure 4a has openings 40 with a quadrilateral cross section, the openings 40 being surrounded and separated from each other by the separating elements 42. The separating elements 42 are narrow strips with an average width b, for example 2 mm, which completely surrounds 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, for example 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.

[0095] The grid 38 is simply 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 shape, such as a corrugated sheet.

[0096] Grids 38 having openings 40 of various geometries and separating elements 42 of various geometries are shown in Figures 4b to 4f. The openings 40 of the grid 38 in Figures 2b and 2c are quadrilateral, the openings 40 of the grid 38 in Figure 2d are irregular, and the openings 40 of the grid 38 in Figures 2e and 2f are elliptical. They may also be lenticular in shape.

[0097] 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 the structural packing element according to the invention is then explained with reference to Figures 5a and 5b. First, a number of plan views of one of the openings 40, 40' of the structural 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 distance on the plan and the apparent distance z measured on the real object is used to scale all other distances measured on the plan.

[0098] 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. 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.

[0099] 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.

[0100] 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 above.

[0101] 6 shows the determination of the minimum deformation area of ​​the structural filler element made of the corrugated sheets 24, 24' as layers 32, 32'. As mentioned above, in a preferred embodiment of the invention, the layers 32, 32' of the structural filler 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, the corrugated sheets 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'.

[0102] 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 filling elements 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 structural packing elements that satisfies this statement is considered to be a layer made of a uniform grid.

[0103] The above observations also apply to layers of any different shape, this is not limited to corrugated layers only.

[0104] 7a is a schematic top view of an expanded metal sheet of a layer of structural cross-channel filler elements according to another embodiment of the present invention. The top view is made by taking a photographic image of the expanded metal sheet after it has been laid on a flat surface and flattened by placing a plate on top of the expanded metal sheet and pressing the plate downwards on top of the expanded metal sheet with a pressure small enough only to flatten the expanded metal sheet without changing the geometry and dimensions of the separating elements and openings. The expanded metal sheet has openings 40, 40', 40'', 40'' having a substantially trapezoidal configuration, separated from each other by separating elements 42. Thus, the opening 40, 40', 40'' has a shorter characteristic length e2 and a longer characteristic length e1, the shorter characteristic length e2 of the opening 40, 40', 40'' being the maximum distance of the opening in the stretch direction SD of the expanded metal sheet, and the longer characteristic length e1 of the opening 40, 40', 40'' being the maximum dimension of the opening in a direction perpendicular to the stretch direction SD of the expanded metal sheet. The stretch direction SD of the expanded metal sheet is the direction along which the sheet metal is stretched during production of the expanded metal sheet. For example, the longer characteristic length e1 of the opening 40, 40', 40'' can be determined by measuring the distance between the leftmost point and the rightmost point of the edge of the opening 40'' in a direction perpendicular to the stretch direction SD of the expanded metal sheet, whereas the shorter characteristic length e2 of the opening 40, 40', 40'' can be determined by measuring the distance between the uppermost point and the lowermost point of the edge of the opening 40. To determine the characteristic lengths e1 and e2 particularly accurately, the respective dimensions can be measured at at least five different openings 40, 40', 40'', more preferably at least ten different openings 40, 40', 40'', and then the sum of the measurements is divided by five or ten, respectively.

[0105] The distance u1 between two openings 40, 40', 40'' adjacent to each other in the direction perpendicular to the stretch direction SD of the expanded metal sheet and separated by a separating element 42 is determined by measuring the distance between the outermost point on one side of the edge of the opening 40 and the outermost point on the same side of the edge of the adjacent opening 40'' in the direction perpendicular to the stretch direction SD of the expanded metal sheet. In FIG. 7a, the distance u1 is determined by measuring the distance between the outermost point on the left side of the edge of the opening 40 and the outermost point on the left side of the edge of the adjacent opening 40'' in the direction perpendicular to the stretch direction SD of the expanded metal sheet. In addition, the distance u2 between two openings 40, 40' adjacent to each other in the direction of stretch SD of the expanded metal sheet and separated by a separating element 42 is determined by measuring the distance between the outermost point on one side of the edge of the opening 40 in the stretch direction SD of the expanded metal sheet and the outermost point on the same side of the edge of the adjacent opening 40' in the stretch direction SD of the expanded metal sheet. In FIG. 7a, the distance u2 is determined by measuring the distance between the uppermost point on the upper side of the edge of the opening 40 in the stretch direction SD of the expanded metal sheet and the uppermost point on the upper side of the edge of the adjacent opening 40' in the stretch direction SD of the expanded metal sheet. In order to determine the distance u1 particularly accurately, the distance u1 can be determined by measuring the distance between the outermost point on one side of the edge of the opening 40 in a direction perpendicular to the stretch direction of the expanded metal sheet and the outermost point on the same side of the edge of the fifth or tenth adjacent opening in the same direction of the expanded metal sheet and dividing this distance by 4 or 9, respectively. Similarly, the distance u2 can be determined by measuring the distance between the outermost point on one side of the edge of the opening 40 in the stretch direction of the expanded metal sheet and the outermost point on the same side of the edge of the fifth or tenth adjacent opening that is located relative to the opening 40 in the stretch direction of the expanded metal sheet and dividing this distance by 4 or 9, respectively.

[0106] Again, using the factor z / z' defined above, the dimensions determined on the photographic image can be converted to actual lengths.

[0107] If the openings are exactly diamond shaped, the area and perimeter P of the openings 40, 40', 40'', 40''' can be obtained from the values ​​mentioned above by the following equation: A=e1·e2 / 2 P=2 √(e1 2 +e2 2 )

[0108] In addition, expanded metal sheets are S It can be characterized by a stretch factor defined as:

[0109] 7b and 7c are schematic views along plane A of FIG. 7a and plane B of FIG. 7b, respectively. As shown in these figures, the expanded metal sheet resulting from the production process, i.e. obtained by cutting and stretching a metal plate, 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 (e.g. tilting) of the separating elements with respect to the others. Other features such as burrs may arise from the drilling process and thus contribute to the thickness. The resulting dimension of the expanded metal sheet is the grid thickness g, which may be equal to the layer material thickness (this is the case when the expanded metal sheet is flat because it is flattened by rolling) or may be several times larger than the layer material thickness. Another embodiment of the invention comprises rolling the expanded metal sheet to provide it with a textured surface. More specifically, each of the periodic deformations, especially corrugations, can have a descending surface with a patterned front surface including a plurality of protrusions and recesses, which define a continuous transverse capillary channel. The protrusions can be arranged to abut adjacent protrusions, can have side walls defining channels therebetween, and can have a patterned back surface equal to the front surface, as disclosed in EP0190435B1, which defines a continuous transverse capillary channel. The protrusions can have a height in a range equivalent to the grid thickness g without any further processing. The grid thickness g is usually of the order of magnitude of the width b of the separating element and should not be significantly larger than the width b. Thus, the ratio of the grid thickness g to the average width b of the separating element is most preferably in the range of 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.

[0110] Figure 8 is a schematic plan view of an expanded metal sheet of a layer of structural cross channel filler element shown in Figure 7. This plan view was obtained as described above.

[0111] Figure 9 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 9a shows a cross-section of a typical layer of structural packing elements 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 8b to 8d the area on this layer is represented only by thin lines following the contour of the layer. The physical area A of the structural packing layer 32, 32' P is shown in FIG. 9b. 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 (which have a standard width s) 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 structural filling 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. 9c. 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 By adding these together, the sheet area A of the structural filling element 12 is obtained. S The geometric area A of the layer is obtained as defined in FIG. 9d 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 layer S 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 Because it consists of specific area a M is the geometric area A of the structural filling element M Let V be the volume occupied by the structural filling element. M It is defined as dividing by.

[0112] 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 conditions of total reflux. Patent EP 0 995 958 B1 discloses such a test with oxygen and argon at a pressure of 152 kPa (22 psiа). US Pat. No. 6,874,769 (B2) discloses the testing of structured packing elements by using the close-boiling binary mixture para-xylene and ortho-xylene. In the present invention, a binary mixture with similar ideal properties was used as this mixture, namely monochlorobenzene (low boiling solvent) and ethylbenzene (high boiling solvent). 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.

[0113] A sufficient amount of the binary mixture was packed 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 packing bed. After flowing slowly through the 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 duty of the condenser in combination with a vacuum pump to remove excess inert gas.

[0114] After a period of operation at a constant reboiler duty, a steady state condition was achieved. At this point, the pressure drop across the packing 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 packing bed and from a collector at the lower end of the packing bed or from a sump. Multiple operating points were measured by varying the heat exchange rate (and cooling duty) affecting the coefficient F (vapor flow) and the associated liquid flow through the packing bed while keeping the head pressure constant. The same experiment was repeated at multiple head pressure settings.

[0115] 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

[0116] A high NTSM (or low HETP) means good mass transfer efficiency.

[0117] 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 packing bed. Alternatively, an average value can be calculated taking into account the changes over the bed. For comparison purposes, any of the approaches considered are valid, provided that the same approach is used for all tests.

[0118] 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.

[0119] The pressure drop across the packing bed was another relevant result of the experiment. The pressure drop was calculated by dividing the difference in pressure readings at the top and bottom of the packing bed by the bed height H. B obtained by dividing by: ΔP / Δz=(p top -p bottom ) / H B

[0120] In the present examples and comparative examples, five types of structural packing elements were used, named P1-250, R-250, P2-500, P3-500 and R-500. The structural packing elements P1-250 and P2-500 were cross-channel corrugated packing made of layers according to the invention, whereas the structural packing elements P3-500, R-250 and R-500 were structural packing elements not according to the invention. More specifically, the structural packing elements R-250 and R-500 were known standard cross-channel corrugated packing 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 structural packing elements had a height of about 200 mm. The relevant parameters of the structural filling elements mentioned above are summarized in Surface 1. [Table 1]

[0121] "Example 1 and Comparative Example 1" The packing element P1-250 according to the invention and the reference 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 using monochlorobenzene and ethylbenzene at head pressures of p=960 hPa (960 mbar) (close to atmospheric) and p=100 hPa (100 mbar). The packing bed had a height of 4.3 m. The efficiency curves obtained are shown in Figs. 10 and 11. In both cases, the packing element P1-250 according to the invention shown showed a higher mass transfer efficiency (higher NTSM) compared to the reference 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 shows a 30% lower material usage (20% lower physical area A) than the reference packing element R-250. P ) achieves better mass transfer results.

[0122] The pressure drops of both structural packing elements are shown in FIG. 12. The pressure drops were very similar. Thus, the structural packing element P1-250 according to the invention had a higher pressure drop at low coefficient F, but with a less steep slope. This gave the new packing a capacity advantage. The P-250 had a lower pressure drop at high flow rates.

[0123] "Example 2 and Comparative Examples 2 to 3" The structural packing element P2-250 according to the invention and the reference structural 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 head pressures of p=960 hPa (960 mbar) and p=100 hPa (100 mbar). In addition, the structural packing element P3-500 was tested. Although similar to P2-500, the structural 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 structural packing element P3-500, the ratio between the distance u1 between adjacent openings, measured perpendicular to the stretching direction, and the average width of the separating element u1 / b was 7.2, 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 were outside the numerical ranges specified above in the present invention. The packing beds using P2-500 and P3-500 had a height of 2.4 m, while the packing bed using the baseline R-500 had a height of 2.6 m.

[0124] The resulting efficiency curves for these structural packing elements are shown in FIGS. 13 and 14, and the resulting pressure drops for these structural packing elements are shown in FIG.

[0125] The better efficiency of the packing element P2-500 according to the invention compared to the packing elements P3-500 and R-500 (not according to the invention) at both 960 mbar and 100 mbar top pressures can be easily deduced from Figures 13 and 14. The gap in mass transfer efficiency is particularly visible at low top 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 packing elements P2-500 and P3-500 have a higher pressure drop than R-500 in the initial state, but as F increases, these packing elements benefit and both capacities are higher in this graph. [Explanation of symbols]

[0126] 10 Mass transfer columns / distillation columns 12 Structural cross-channel filling elements 14, 14' Bed of structural filler elements 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 / open space 32, 32' layer 33, 33' End of corrugated sheet 34 Dimples 36 Dimple Valley Wall 38 Grid 40, 40', 40'', 40'' Grid openings 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 structural filling element made of corrugated layers A Cross-sectional area of ​​opening a1 Side length of opening a2 Second side length of opening a M Specific area of ​​packing or layer A j Opening section area A M geometric area A P physical area A S Seat area 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 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 SD Expanded metal sheet stretch direction u1 Distance between two adjacent openings in the expanded metal sheet in the direction perpendicular to the stretching direction u2 Distance between two adjacent openings in the direction of expansion of the expanded metal sheet 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 structural cross-channel packing element (12) for a column (10) for mass transfer and / or heat exchange between a heavy fluid phase and a light fluid phase, comprising: said structural cross-channel filler element (12) having at least two adjacent layers (32, 32') made of expanded metal sheets each having openings (40, 40', 40'', 40''') surrounded and separated from one another by a separating element (42); at least two of the at least two layers (32, 32') are arranged in a longitudinal direction (V) of the packing element (12) so as to be parallel to and in contact with each other, whereby an open space (30) is provided between the at least two layers (32, 32') extending from one end to an opposite end of the at least two layers (32, 32'), whereby at least one of the heavy fluid phase and the light fluid phase can flow through the open space (30); a ratio between an average width (b) of at least 50% of the separating element (42) between adjacent openings (40, 40', 40'', 40''') and a sheet material thickness (s) of at least 15, a ratio between a maximum distance (D) between at least two of the at least two layers (32.32') measured in a plane perpendicular to the longitudinal direction (V) and the average width (b) of the separating element (42) of at least 4, and a distance (u) between two openings (40, 40'') adjacent to the separating element (42) in a direction perpendicular to the stretching direction of the expanded metal sheet ... １ ) to said average width (b) of said separating elements (42) is between 4 and 6 for at least 50% of all separating elements (42); The distance (u １ ) is measured by determining the distance between the outermost point on one side of an edge of an opening (40) in a direction perpendicular to the stretch direction of the expanded metal sheet and the outermost point on the same side of an edge of an adjacent opening (40''') in the same direction of the expanded metal sheet, the longitudinal direction of the filler element (12) is as defined herein, the stretch direction of the expanded metal sheet is perpendicular to the longitudinal direction (V) of the structural cross-channel filler element (12), and a structural cross-channel filler element (12) wherein the average width (b) of a separation element (42) is determined by dividing the separation element (42) into individual sections i=1, 2, 3,... n, each having a section length di, and for each of the sections, the shortest distance b between adjacent edges within 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).

2. 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 said at least two layers (32, 32') are made of expanded metal sheets and have periodic deformations (26, 28, 34); the layers (32, 32') are oriented such that the periodic deformations (26, 28, 34) of the adjacent layers (32, 32') cross in a crisscross manner with the periodic deformations (26, 28, 34) of the layers (32, 32') that extend obliquely with respect to the longitudinal direction (V); each layer (32, 32') contacts each of the adjacent layers (32, 32') at a crossover point between the periodic deformation portion (26, 28, 34) of the layer (32, 32') and the deformation portion of the adjacent layer (32, 32'); and The structural filler element (12) of claim 1, wherein the open space (30) between the at least two layers (32, 32') is defined by the periodic deformation portions (26, 28, 34).

3. The distance (u １ 3. A structural packing element (12) according to claim 1 or 2, wherein the ratio between the average width (b) 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 separating elements (42) is between 4 and 6, preferably between 4.5 and 5.5, more preferably between 4.9 and 5.

1.

4. 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 at all openings (40, 40', 40'', 40''). １ 4. A structural filler element (12) according to any one of claims 1 to 3, wherein the thickness of the filler is between 5 mm and 20 mm, preferably between 7.5 mm and 15 mm, more preferably between 9 mm and 11 mm.

5. The distance (u) between adjacent first openings (40) and second openings (40') in the stretching direction of the expanded metal sheet, which is perpendicular to the longitudinal direction (V), is ２ ) and the distance (u ) between the first opening (40) and the third opening j (40 ″) adjacent to each other in a direction perpendicular to the stretching direction of the expanded metal sheet. １ ) is 0.4 to 0.7; The distance (u ２ ) is measured by determining the distance between the outermost point on one side of the edge of the first opening (40) in the stretching direction of the expanded metal sheet and the outermost point on the same side of the edge of the adjacent second opening (40') adjacent in the stretching direction of the expanded metal sheet; and The distance (u １ 5. A structural filler element (12) according to claim 1, wherein the width of the expanded metal sheet is measured by determining the distance between the outermost point on one side of the edge of the first opening (40) in a direction perpendicular to the direction of extension of the expanded metal sheet and the outermost point on the same side of the edge of the adjacent third opening (40''') in the same direction of the expanded metal sheet.

6. 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 at all openings (40, 40', 40'', 40''). ２ ) and the distance (u １ 6. A structural packing element (12) according to any one of claims 1 to 5, wherein the ratio between the number of layers and the number of layers is from 0.4 to 0.7, preferably from 0.45 to 0.70, more preferably from 0.49 to 0.

55.

7. 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 at all openings (40, 40', 40'', 40''). ２ 7. A structural filler element (12) according to any one of claims 1 to 6, wherein the thickness of the filler is between 2 mm and 8 mm, preferably between 3 mm and 7 mm, more preferably between 4 mm and 6 mm.

8. 8. A structural packing element (12) according to any one of claims 1 to 7, wherein 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 (42) between adjacent openings (40, 40', 40'', 40''') is between 1.5 mm and 4 mm, preferably between 1.6 mm and 3.5 mm, and most preferably between 1.8 mm and 3.0 mm.

9. 9. A structural packing element (12) according to any one of claims 1 to 8, wherein the ratio between the average width (b) of at least one separation element (42) between adjacent openings (40, 40', 40'', 40''') and the sheet material thickness (s) is at least 18.

10. 10. A structural packing element (12) according to any one of claims 1 to 9, wherein the ratio between the maximum distance (D) measured in the plane perpendicular to the longitudinal direction (V) and the average width (b) of the separating elements (42) is between 4 and 15, preferably between 5 and 13, most preferably between 8 and 12, between at least 50% of the at least two layers (32, 32'), preferably between at least 75%, more preferably between at least 80%, even more preferably between at least 90%, even more preferably between at least 95% and most preferably between all of the at least two layers (32, 32').

11. In at least 50%, preferably at least 75%, more preferably at least 80%, even more preferably at least 90%, and even more preferably at least 95% of the at least two layers (32, 32'), the total area of ​​the openings (40, 40', 40'', 40''') is equal to or greater than the sheet area (A Ｓ 11. A structural packing element (12) according to any one of claims 1 to 10, wherein the ratio, when divided by the ratio of the number of layers, is between 20% and 38%, preferably between 25% and 35%, and most preferably between 28% and 32%.

12. 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 said openings (40, 40', 40'', 40''') have a shorter characteristic length (e) of between 1 mm and 4 mm, preferably between 2 mm and 3 mm. ２ ) and a longer characteristic length (e) of 2 mm to 8 mm, preferably 2.5 mm to 7 mm, and most preferably 3 mm to 6 mm. １ ) and The shorter characteristic length (e ２ ) is the maximum dimension of the opening (40, 40', 40'', 40''') in the stretching direction of the expanded metal sheet, and the longer characteristic length (e １ 12. A structural filler element (12) according to claim 1, wherein .gamma. is the maximum dimension of the openings (40, 40', 40'', 40''') in a direction perpendicular to the stretching direction of the expanded metal sheet.

13. 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 (40, 40', 40'', 40''') have the shorter characteristic length (e ２ ) and the longer characteristic length (e １ 13. A structural filler element (12) according to any one of claims 1 to 12, wherein the ratio between the thickness of the filler and the thickness of the outermost layer is between 0.4 and 0.7, preferably between 0.45 and 0.6 mm, most preferably between 0.49 and 0.55 mm.

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

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

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