Structured packing bed for high pressure mass transfer and / or heat exchange applications

Abstract

The invention relates to a structured packing bed for a column for mass transfer and / or heat exchange between a first and a second fluid phase, wherein the column for mass transfer and / or heat exchange is designed for operation at a pressure of at least 6 bar, wherein the structured packing bed comprises at least two layers, wherein the at least two layers are stacked vertically on top of each other, and wherein at least two of the at least two layers each comprise at least one structured cross-channel packing element having a specific surface area of 60 to 500 m2 / m3 and a height of 50 to less than 150 mm, wherein at least 50% of all structured cross-channel packing elements are blocks, wherein each block comprises a plurality of sheets having periodic deformations, wherein the sheets are arranged parallel and in contact with each other in a longitudinal direction such that between them an open space is provided extending from one end of the sheets to the opposite end, wherein the open space is defined by the periodic deformations, wherein adjacent sheets are oriented such that the periodic deformations of adjacent sheets intersect each other in a cross-like manner, and wherein at least one of the structured cross-channel packing elements of a layer is rotated by 70 to 110° with respect to at least one of the structured cross-channel packing elements of an adjacent layer.

Description

Technical Field

[0001] This invention relates to a structured packed bed for a tower used for mass transfer and / or heat exchange between first and second fluid phases, wherein the tower is designed to operate at a pressure of at least 6 bar. Furthermore, this invention relates to a tower for mass transfer and / or heat exchange comprising such a structured packed bed, and a method for mass transfer and / or heat exchange using a mass transfer and / or heat exchange tower operating at a pressure of at least 6 bar, and preferably at least 10 bar. Background Technology

[0002] Structured packed beds, comprising multiple structured packing elements, are used in mass transfer and / or heat exchange columns, such as fractionation columns, distillation columns, absorption columns, extraction columns, or flue gas scrubbers. A structured packed bed comprises multiple layers stacked vertically on top of each other, each layer consisting of one or more structured packing elements. The larger the diameter of the structured packed bed, the greater the number of structured packing elements per layer. The structured packing elements are used to improve mass transfer and / or heat exchange between at least two fluid phases of different densities, wherein the structured packing elements typically operate in a countercurrent flow manner. In distillation and absorption applications, the lighter phase is a gas or vapor, and the heavier phase is a condensate or liquid; in extraction, the two phases are liquids of different densities. The structured packing element comprises multiple different sheets, each sheet providing a surface area for the heavier phase to drip and diffuse along its surface. Furthermore, open spaces are provided between the different sheets of the structured packing element, these open spaces being filled with the lighter phase (e.g., vapor or gas in distillation) and providing a path for the lighter phase to rise, driven by a pressure gradient. A pressure gradient is required to overcome flow resistance. In typical countercurrent flow, the average flow direction of the lighter phase is from the bottom to the top of the structured packing element, and therefore opposite to the average flow direction of the heavier phase. By diffusing a heavier phase on the surface of the structured packing element, an interface is created between at least two phases, thereby establishing effective heat and mass transfer between the phases at the interface. Applications with more than one heavier phase can also exist. One example is extractive distillation.

[0003] Mass transfer towers typically comprise multiple beds of structured packing elements. Typically, a distributor is positioned at the top of each bed to evenly distribute the heavy phase across the bed's cross-section, while allowing sufficient space for the light phase to rise through it. Furthermore, a grid-like holding device and a collector are usually arranged below each bed, where the grid structure holds the bed in place, and the collector collects the heavy phase dripping from the bed, while leaving sufficient open space within the collector for the light phase to rise.

[0004] A common type of structured packing element is the so-called cross-channel corrugated sheet packing, which is assembled from multiple corrugated sheets arranged parallel to and in contact with each other. Typically, the corrugated metal sheets are secured to each other by multiple rods penetrating the corrugated sheets perpendicular to their longitudinal sections. These rods are secured to the first and last corrugated sheets by means of washers and nuts or by bending the rods. Each corrugated sheet includes multiple alternating peaks and valleys, wherein adjacent corrugated sheets are oriented such that the corrugations of adjacent sheets intersect with the corrugations of sheets extending obliquely relative to the vertical or longitudinal direction in a crisscross fashion, thus forming continuously intersecting oblique channels. These channels actively influence the flow of gas and liquid phases within the packing and promote mass and / or heat transfer between the phases. That is, the gas and liquid phases contact within the channels of the structured packing element, thus promoting mass and heat transfer between the phases. More specifically, the rising gas comes into contact with a liquid present on the surface of the sheet forming the channels as it flows downward through the mass transfer tower. During this contact, gas-rich components can transfer into the liquid and vice versa; this means that efficient mass transfer can occur. Such packing is described, for example, in DE1253673, US6,206,349B1, EP3299087A1, and US5,632,934.

[0005] Commercially available structured cross-channel corrugated sheet packing elements range in height from 180 to 300 mm. EP3299087A1 describes packing elements with a typical height of 200 to 300 mm and recommends the use of taller packing elements with a height of 350 to 400 mm. In US5,632,934, structured packing elements have a height of 6 to 12 inches, or 152.4 to 304.8 mm.

[0006] If necessary, for adjusting the overall height of the structured packing bed or for good initial liquid distribution, the top layer of the structured packing bed may sometimes consist of shorter structured packing elements. However, even in this case, the remaining layers, which typically comprise well over 90% of all layers, consist of standard-sized structured packing elements with the aforementioned height, typically between 180 and 300 mm.

[0007] Certain mass transfer applications (e.g., distillation of volatile materials) require operating mass transfer columns at considerably high pressures, at least 6 bar or even at least 10 bar. High pressures are necessary for distilling volatile materials to raise their condensation temperatures to desired levels, or to allow these light hydrocarbons to condense separately at cost-effective temperatures. A prominent example of such applications is the separation of light hydrocarbons, such as methane, ethane, propane, etc., found, for example, in petroleum and natural gas sources. However, structured packed elements can exhibit lower efficiency in industrial-scale columns when operated at such high pressures. The reason for the decrease in mass transfer efficiency at higher pressures is described in the literature as axial liquid backmixing (backmixing). High-pressure applications are typically characterized by low liquid density and very low surface tension, but high vapor density, and this combination allows for high buoyancy, which lifts small droplets upwards with the vapor phase, resulting in axial backmixing within the column. On the other hand, the vapor phase is dragged down by the descending liquid phase and also undergoes some backmixing. A reversal point has also been reported at certain higher pressures, where the flow behavior changes drastically, leading to significant changes in pressure drop and separation efficiency. For example, such a reversal point occurs at approximately 10 bar for distilling isobutane and n-butane using a column with a structured packed bed composed of commercially available cross-channel corrugated sheet packing elements. This behavior is typical for structured packed elements but not for random packing, for example. In random packing, the volume is more open in all three dimensions and neither the gas nor the liquid phase is trapped. Therefore, local differences in the vapor-liquid flow are compensated for more quickly in random packing, and small droplets dragged by the vapor flow collide with the packing more rapidly, resulting in better separation of small droplets from the vapor flow compared to the straight corrugated channels of structured packed elements. However, the multiple redirections of the vapor flow within random packing significantly increase the pressure drop. Summary of the Invention

[0008] In view of the above, the fundamental object of the present invention is to provide a structured packed bed for a tower for mass transfer and / or heat exchange between a first and a second fluid phase, wherein the tower is designed to operate at a pressure of at least 6 bar, and preferably at least 10 bar, the structured packed bed combining the advantages of random packing and structured cross-channel packing, i.e., the structured packed bed has high mass transfer efficiency even when operating at pressures above 10 bar as in random packing, but still has a relatively low pressure drop as in structured cross-channel packing.

[0009] According to the invention, this objective is achieved by providing a structured packed bed for a tower for mass transfer and / or heat exchange between first and second fluid phases, wherein the tower for mass transfer and / or heat exchange is preferably designed to operate at a pressure of at least 6 bar, and more preferably at a pressure of at least 10 bar, wherein the structured packed bed comprises at least two layers, wherein the at least two layers are vertically stacked on top of each other, and wherein each of the at least two layers comprises at least one structured cross-channel packing element having a diameter of 60 to 500 m. 2 / m 3 The specific surface area and height of 50 to less than 150 mm, wherein preferably, at least 50% of all structured cross-channel filler elements are blocks, wherein each block comprises a plurality of sheets having periodic deformation portions, wherein the sheets are arranged parallel to each other in the longitudinal direction and in contact, such that an open space is provided between them extending from one end of the sheet to the opposite end, wherein the open space is defined by the periodic deformation portions, wherein adjacent sheets are oriented such that the periodic deformation portions of adjacent sheets intersect each other in a cross-shaped manner, and wherein preferably, at least one of the structured cross-channel filler elements in the layer is rotated 70 to 110° relative to at least one of the structured cross-channel filler elements in the adjacent layer.

[0010] This solution is based on the remarkable finding that if a mass transfer and / or heat exchange tower comprises one or more structured packed beds, the tower can operate with high mass transfer efficiency and low pressure drop even at pressures of at least 6 bar and even greater than 10 bar or even greater than 15 bar, wherein the one or more structured packed beds are composed of, or at least primarily composed of, materials with a packing depth of 60 to 500 m³. 2 / m 3 The structured cross-channel packing bed consists of a specific surface area and a height of 50 to less than 150 mm. It is not desirable to be bound by any particular theory, but it is believed that by shortening the height of the structured cross-channel packing elements, the aforementioned backmixing, and especially axial backmixing, can be significantly reduced, even and particularly if the mass transfer and / or heat exchange tower operates at pressures greater than 10 bar. This is thought to be due to the interruption or shortening of the considerably long flow paths within the known structured cross-channel packing elements, respectively. Furthermore, the preferred rotation of 70 to 110° between adjacent structured cross-channel packing elements in adjacent layers results in particularly good gas distribution within the structured packed bed. In summary, the structured packed bed according to the invention allows for the combination of the advantages of random packing and structured cross-channel packing, i.e., high mass transfer efficiency even when operating at pressures above 10 bar, while still maintaining a considerably low pressure drop.

[0011] According to the present invention, the height of at least one structured cross-channel packing element in at least two layers of the structured packed bed is 50 to 150 mm. If the height is higher than 150 mm, the aforementioned disadvantage of reduced mass transfer efficiency occurs when the structured packed bed operates under high pressure. When the height is less than 50 mm, the mass transfer efficiency also decreases because the length of the fluid path within the structured cross-channel packing element is too short. Particularly good results are obtained when the height of at least one structured cross-channel packing element is 50 to less than 150 mm, more preferably 50 to 145 mm, even more preferably 50 to 140 mm, even more preferably 60 to 130 mm, even more preferably 70 to 120 mm, and most preferably 75 to 110 mm.

[0012] Furthermore, according to the present invention, the specific surface area of ​​at least one structured cross-channel packing element in at least two layers of the structured packing bed is 60 to 500 m². 2 / m 3 If the specific surface area is higher than 500 m² 2 / m 3 Structured packed beds composed of structured cross-channel packing elements are unsuitable for high-pressure applications. This is due to the fact that packing with such a high specific surface area has small corrugated channels. In high-pressure distillation, the liquid velocity is relatively high, making it difficult for the liquid to travel through these smaller channels without bridging the channel cross-section. However, when the liquid bridges this cross-section, upward vapor flow is not permitted; therefore, the liquid will travel downwards along one section, and the vapor will be forced to flow upwards along another section. Thus, during high-pressure distillation, the separation of vapor and liquid flows in such structured cross-channel packing elements with such a high specific surface area will significantly reduce efficiency. Therefore, packing beds with 60 to 500 m... 2 / m 3 Cross-channel packing elements with a specific surface area cannot be used with, for example, those with a surface area greater than 600 m². 2 / m 3 Compared to structured cross-channel packing elements with high specific surface area, the latter are specifically designed for low-pressure, and particularly cryogenic distillation applications, such as cryogenic distillation of air. Distillation columns for this application are constructed within cold boxes with limited dimensions, such as limited column size, and particularly limited column height, as column height is a critical dimension that needs to be minimized in such applications. For these reasons, such columns require structured packed beds made of structured packing elements with high specific surface area in order to reduce the height of the structured packed bed and achieve some nominal improvement in efficiency. When the specific surface area of ​​at least one structured cross-channel packing element is 60 to less than 500 m², 2 / m 3 Preferably 100 to less than 500m 2 / m 3More preferably 100 to 400m 2 / m 3 Even more preferably 200 to 400m 2 / m 3 And most preferably 250 to 350m 2 / m 3 At that time, especially good results were obtained.

[0013] In this invention, specific surface area is defined as the geometric area of ​​the structured cross-channel packing element divided by the volume occupied by the structured cross-channel packing element. The geometric area of ​​the structured cross-channel packing element is the sum of the geometric areas of all the sheets included in the structured cross-channel packing element, wherein the geometric areas of the sheets are added together on both sides of the sheet.

[0014] Each layer of a structured packing bed may include one or more structured cross-channel packing elements, wherein the diameter of the structured packing bed tends to increase with the number of structured cross-channel packing elements per layer. In order to have the same performance across the entire cross-section of each layer, a further development of the inventive concept suggests that each layer is uniform across its cross-section. Accordingly, it is preferred that if one or more layers of a structured packing bed include more than one structured cross-channel packing element, all structured cross-channel packing elements in a layer have substantially the same height, and more preferably the same height.

[0015] This invention is particularly applicable to structured packed beds with large cross-sectional areas and mass transfer and / or heat exchange towers. Therefore, it is preferred that the structured packed bed according to the invention has a cross-sectional shape that is at least substantially circular, and the diameter of the structured packed bed is at least 400 mm, preferably at least 600 mm, even more preferably at least 800 mm, even more preferably at least 1 m, even more preferably at least 1.5 m, and most preferably at least 2 m. Further preferably, the diameter of the structured packed bed is at most 15 m, more preferably at most 12 m, and even more preferably at most 6 m. For example, good results are obtained when the diameter of the structured packed bed is 1.5 to 12 m or 1.5 to 6 m.

[0016] If the structured packing bed according to the invention has a cross-sectional shape different from that of a substantially circular cross-section, such as a rectangular or oval cross-section, then it is preferred that the longest dimension of the cross-section of the structured packing is at least 400 mm, preferably at least 600 mm, even more preferably at least 800 mm, even more preferably at least 1 m, even more preferably at least 1.5 m, and most preferably at least 2 m. Further preferably, the longest dimension of the structured packing bed is at most 15 m, more preferably at most 12 m, and even more preferably at most 6 m. For example, good results are obtained when the longest dimension of the structured packing bed is 1.5 to 12 m or 1.5 to 6 m.

[0017] According to the present invention, at least two layers of the structured packing bed each include at least one structured cross-channel packing element, the structured cross-channel packing element having a diameter of 60 to 500 m. 2 / m 3 The specific surface area and height are 50 to less than 150 mm. However, if any of these at least two layers contains more than one structured cross-channel packing element, it is preferred that all structured cross-channel packing elements in the layer have substantially the same specific surface area, and more preferably the same specific surface area. In this respect, substantially the same specific surface area means that the specific surface area of ​​each structured cross-channel packing element in the layer is 80 to 120%, preferably 90 to 110%, more preferably 95 to 105%, and even more preferably 98 to 102% of the average specific surface area of ​​all structured cross-channel packing elements in the layer. The average specific surface area of ​​all structured cross-channel packing elements in a layer is determined by adding the specific surface areas of all structured cross-channel packing elements in the layer and dividing the sum by the number of structured cross-channel packing elements in the layer.

[0018] In principle, in addition to one or more structured cross-channel packing elements, each of at least two layers of the structured packing bed may also include one or more other structured packing elements. However, it is preferred that one layer and preferably all layers of the structured packing bed contain only structured cross-channel packing elements.

[0019] According to another preferred embodiment of the invention, the structured packing bed comprises 2 to 30 layers, more preferably 8 to 25 layers, and most preferably 12 to 20 layers, wherein each layer comprises one or more structured cross-channel packing elements or is composed of one or more structured cross-channel packing elements. When each layer consists only of structured cross-channel packing elements, and particularly only of elements having a density of 60 to 500 m... 2 / m 3The best results are obtained when the structured packing bed consists of structured cross-channel packing elements with a specific surface area of ​​60 to less than 150 mm and a height of 50 to less than 150 mm. However, to adjust the total height of the structured packing bed, it is possible to include a layer, particularly the top layer, in the structured packing bed, which consists of structured cross-channel packing elements with different heights, or even structured packing elements that are not cross-channel packing elements. Furthermore, if the total number of layers in the structured packing bed is sufficiently high, it is possible to include one or more intermediate layers in the structured packing bed, which consists of structured packing elements that are not cross-channel packing elements, or structured cross-channel packing elements with a height different from 50 mm to less than 150 mm. In view of this, it is preferred that at least 50%, more preferably at least 75%, even more preferably at least 90%, even more preferably at least 95%, and most preferably all layers of the structured bed comprise a specific surface area of ​​60 to 500 m². 2 / m 3 and at least one structured cross-channel packing element with a height of 50 to less than 150 mm. For all those layers that include more than one structured cross-channel packing element, it is preferred that all structured cross-channel packing elements in the layer have these characteristics, and that the layers do not include any structured packing element that is not a structured cross-channel packing element.

[0020] As described above, preferably, all structured cross-channel packing elements used according to the invention (and therefore preferably, have a diameter of 60 to 500 m) 2 / m 3At least 50% of the structured cross-channel packing element (with a specific surface area of ​​50 to less than 150 mm and a height of 50 mm) is a block, wherein each block comprises a plurality of sheets having periodically deformed portions, wherein the sheets are arranged parallel to and in contact with each other in a longitudinal direction (V), such that an open space is provided between the sheets extending from one end of the sheet to the opposite end, wherein the open space is defined by the periodically deformed portions, and wherein adjacent sheets are oriented such that the periodically deformed portions of adjacent sheets intersect each other in a cross-shaped manner. To achieve the effects of the invention to a sufficiently high degree, it is preferred that at least 75% of all structured cross-channel packing elements, more preferably at least 90% of all structured cross-channel packing elements, even more preferably at least 95% of all structured cross-channel packing elements, and most preferably all structured cross-channel packing elements are such blocks. The longitudinal direction of a structured cross-channel packing element is the average direction of the structured cross-channel packing element, wherein during its operation, such as in a column used for mass transfer and / or heat exchange (e.g., in a distillation column), the light phase rises and the heavy phase falls. Although the light phase may be divided into multiple streams with completely different orientations due to the interaction with the shape of the structured cross-channel packing element, the average direction of the light phase coincides with the longitudinal direction, which is typically vertical or at least close to vertical.

[0021] Since the stability of structured cross-channel filler elements is mainly related to the intersection points between adjacent sheets, the cross channel should have at least two intersection points along its length.

[0022] In a further development of the inventive concept, it is proposed that in the above embodiments, the periodic deformation portion is a corrugated portion comprising a plurality of alternatingly oriented peaks and valleys. The corrugated portion may have a square, triangular, sinusoidal, or zigzag cross-section. Preferably, the corrugated portion has a sinusoidal cross-section. Therefore, preferably, at least 50%, preferably at least 75%, more preferably at least 90%, even more preferably at least 95%, and most preferably all of the structured cross-channel packing elements are blocks, wherein each block comprises a plurality of sheets having a plurality of alternatingly oriented peaks and valleys, wherein the peaks of the sheets contact the valleys of adjacent sheets, and the valleys of the sheets contact the peaks of adjacent sheets, wherein the adjacent sheets are oriented such that the peaks and valleys of the adjacent sheets intersect with the peaks and valleys of the sheets preferably extending obliquely relative to the longitudinal direction of the structured cross-channel packing element in a cross-shaped manner.

[0023] In this embodiment, particularly good results are obtained when the angle α between each peak and each valley of the structured cross-channel packing element and the longitudinal direction is 10° to 60°, preferably 20° to 50°, and most preferably 25° to 47°, wherein the peaks and valleys of adjacent sheets are preferably oriented in opposite directions. This allows for a uniform distribution of the light phase in at least one direction of the cross-section of the structured cross-channel packing element. The angle should not be too large to minimize pressure drop and maximize capacity.

[0024] To reduce pressure loss in the structured cross-channel packing element, a further development of the invention proposes that the peaks and valleys of the structured cross-channel packing element bend relative to the peaks and valleys of the central region arranged between the end regions in the end region of the corrugated sheet, thereby reducing the flow resistance in the end region of the structured cross-channel packing element relative to the flow resistance in the region arranged between the end regions. Therefore, in this embodiment, the peaks and valleys of the corrugated sheet of the structured cross-channel packing element are not linearly extended. Preferably, the peaks and valleys bend in the end region of the corrugated sheet so as to extend at least substantially vertically. Substantially vertical means that the peaks and valleys at the lower and upper edges of the sheet are inclined at an angle α less than the vertical or longitudinal direction of the structured cross-channel packing element, preferably not exceeding 10°; more preferably not exceeding 5°; and even more preferably not exceeding 2°. The end regions are the uppermost and lowermost regions of the corrugated sheet extending 30%, preferably 25%, and more preferably 20% or less from the upper and lower edges of the sheet along its length, the length being along the longitudinal direction of the corrugated sheet. Each end region may have peaks and valleys with heights different from the peaks and valleys of the central region, which is the sheet region between the two end regions. Instead of providing such bends or different heights in both end regions, such bends or different heights may exist only in one of the end regions.

[0025] To achieve excellent gas distribution in the structured packed bed, preferably, at least one of the structured cross-channel packing elements in one layer is rotated 70° to 110° relative to at least one of the structured cross-channel packing elements in the adjacent layer. This means that, viewed in the plane of cross-section, the parallel sheets of one of the corresponding structured cross-channel packing elements are twisted or rotated 70° to 110° relative to the parallel sheets of the corresponding structured cross-channel packing elements in the adjacent layer. Preferably, at least one of the structured cross-channel packing elements in one layer is rotated 70° to 110° relative to at least one of the structured cross-channel packing elements in the adjacent layer arranged above or below it. More preferably, all the structured cross-channel packing elements in one layer and preferably each layer (and therefore preferably have a thickness of 60 to 500 m) are rotated.2 / m 3 At least 50% of the structured cross-channel packing elements (with a specific surface area of ​​50 to less than 150 mm and a height of 50 mm or less) are rotated 70 to 110° relative to adjacent structured cross-channel packing elements in adjacent layers of the structured packing bed. Even more preferably, at least 75%, more preferably at least 90%, more preferably at least 95%, and most preferably 100% of all structured cross-channel packing elements in a layer and preferably each layer are rotated 70° to 110° relative to adjacent structured cross-channel packing elements in adjacent layers of the structured packing bed. Particularly good results are achieved when, in the foregoing embodiments, the corresponding structured cross-channel packing elements are rotated 80 to 100°, more preferably 85 to 95°, and most preferably 88 to 92°, such as 90°, relative to each other.

[0026] The sheets of the structured cross-channel packing elements can be made of metal, plastic, carbon-reinforced carbon, or any other suitable material. Preferably, they are made of metal such as stainless steel.

[0027] Furthermore, in some applications, it may be advantageous for the sheet of the structured cross-channel packing element to include small openings to improve the wettability of the sheet. The invention does not impose any particular limitation on the geometry of the openings. Therefore, the openings can have circular, elliptical, approximately square, rectangular, rhomboid, quadrilateral, hexagonal, trapezoidal, polygonal, or irregular cross-sectional shapes.

[0028] If present, 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 the openings in at least two sheets have a hydraulic diameter of 1.25 to 5.0 mm. Even more 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 the openings in each sheet have a hydraulic diameter of 2.0 to 4.0 mm, and most preferably 2.2 to 3.5 mm. According to the invention, the hydraulic diameter of the opening is calculated using 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, for example, a flat triangle, rectangle, quadrilateral, trapezoid, etc., the cross-sectional area of ​​the opening can be determined by using basic measurements (such as shape length and height) and basic geometric formulas (known from Euclidean geometry). Preferably, the area is determined on a plan view of the opening. Complex shapes can be approximated and subdivided into those with area A. j The quantities j = 1, 2, 3...m are simple shapes. The areas of these shapes can be calculated again using basic measurements and basic geometric formulas. The area A of an opening is obtained by determining all areas A within the opening. jThe results are obtained by addition. The more complex the shape of the opening, the more subdivisions are required. Preferably, the number m of the individual simple shape sections j taken for measurement is 1 to 1000, more preferably 5 to 100, more preferably 5 to 20, such as 8 to 15.

[0029] The structured cross-channel packing element of the structured packing bed of the present invention can be manufactured by any known method for producing a structured cross-channel packing element with a height known in the prior art by using a metal strip with a desired reduced width. Alternatively, the structured cross-channel packing element with a height known in the prior art can be cut / sawed into two or more parts, wherein at least one part has the desired height.

[0030] According to another aspect, the present invention relates to a mass transfer and / or heat exchange tower comprising at least one of the above-described structured packed beds.

[0031] This invention is particularly applicable to mass transfer and / or heat exchange towers with large cross-sectional areas. Therefore, it is preferred that the mass transfer and / or heat exchange tower according to the invention has a cross-sectional shape that is at least substantially circular, and that the inner diameter of the mass transfer and / or heat exchange tower is at least 400 mm, preferably at least 600 mm, even more preferably at least 800 mm, even more preferably at least 1 m, even more preferably at least 1.5 m, and most preferably at least 2 m. Further preferably, the inner diameter of the mass transfer and / or heat exchange tower is at most 15 m, more preferably at most 12 m, and even more preferably at most 6 m. For example, good results are obtained when the inner diameter of the mass transfer and / or heat exchange tower is 1.5 to 12 m or 1.5 to 6 m.

[0032] If the mass transfer and / or heat exchange tower according to the invention has a cross-sectional shape different from that of a substantially circular tower, such as a rectangular or oval cross-sectional shape, then it is preferred that the longest dimension of the cross-section of the mass transfer and / or heat exchange tower is at least 1 m, preferably at least 1.5 m, and more preferably at least 2 m. Further preferred is that the longest dimension of the mass transfer and / or heat exchange tower is at most 15 m, more preferably at most 12 m, and even more preferably at most 6 m. For example, good results are obtained when the longest dimension of the mass transfer and / or heat exchange tower is 1.5 to 12 m or 1.5 to 6 m.

[0033] Preferably, the mass transfer and / or heat exchange tower comprises 1 to 6, and more preferably 1 to 3, structured packed beds.

[0034] Furthermore, preferably, the mass transfer and / or heat exchange tower includes a liquid distributor above each structured packing bed to allow the heavy phase to be distributed at least substantially uniformly across the cross-section of the structured cross-channel packing element bed during operation of the mass transfer and / or heat exchange tower.

[0035] According to another preferred embodiment of the invention, a mass transfer and / or heat exchange tower is proposed to include a collector below the bottom of each structured packed bed, which allows the collection of heavy phase dripping from the surface of the sheet of the structured cross-channel packing element of the layer of the structured packed bed during operation of the mass transfer and / or heat exchange tower.

[0036] Most preferably, the mass transfer and / or heat exchange tower of the present invention is a distillation tower.

[0037] According to another aspect, the present invention relates to a method for mass transfer and / or heat exchange, wherein at least two fluids are guided through the aforementioned mass transfer and / or heat exchange tower, wherein the mass transfer and / or heat exchange tower operates at a pressure of at least 6 bar.

[0038] Preferably, the mass transfer and / or heat exchange tower is operated at a pressure of at least 6 bar, more preferably at least 8 bar, even more preferably at least 10 bar, even more preferably at least 12 bar, and most preferably at least 15 bar.

[0039] When this method is carried out using a distillation column, i.e., when the method is distillation, particularly good results are obtained. In this embodiment, the two fluids are guided through the distillation column in a countercurrent flow manner, wherein the liquid flows from the top of the column to the bottom, and the gas rises from the bottom of the column to the top.

[0040] More specifically, the method of the present invention is particularly suitable for separating light hydrocarbons, such as methane, ethane, propane, butane, ethylene or propylene, by distillation, and especially those methane, ethane, propane, butane, ethylene or propylene found in petroleum sources and natural gas.

[0041] Therefore, the mass transfer and / or heat exchange tower according to the invention is particularly suitable for gas production equipment having a distillation tower that separates light hydrocarbons such as methane, ethane, propane, butane, ethylene or propylene found in petroleum sources and natural gas, or for petrochemical equipment particularly suitable for processing light hydrocarbons, especially for superfractionators that perform difficult separation between liquid hydrocarbons with similar boiling point temperatures. Attached Figure Description

[0042] Specific embodiments of the invention are then described with reference to the accompanying drawings and examples.

[0043] Figure 1This is a schematic side view of a mass and / or heat exchange tower according to an embodiment of the present invention, the mass and / or heat exchange tower comprising two structured packed beds, wherein each structured packed bed comprises multiple layers of structured cross-channel packing elements.

[0044] Figure 2a This is an exploded view of a portion of the sheet material of a structured cross-channel packing element used in a structured packing bed according to an embodiment of the present invention.

[0045] Figure 2b yes Figure 2a A schematic side view of the structured cross-channel packing element shown.

[0046] Figure 3 This is a partial view of a structured cross-channel packing element used in a structured packing bed according to another embodiment of the present invention. Detailed Implementation

[0047] Figure 1 A schematic side view of a mass transfer column 10 and more specifically a distillation column 10 according to an embodiment of the present invention is shown (the transparent interior of the figure is for illustrative purposes only). The distillation column 10 includes two structured packed beds 12, 12', each of which includes multiple layers 13, 13', each layer 13, 13' including multiple structured cross-channel packing elements 14. Above each of the two beds 12, 12', distributors 16, 16' are arranged to uniformly distribute liquid across the cross-section of the structured packed bed 12, 12' while leaving sufficient space for vapor to rise through it. Below each bed 12, 12', a grid-like holding device 18 and a collector 20 (not shown for bed 12') are arranged, wherein the grid-like holding device 18 holds the bed 12 in its position, and the collector 20 collects liquid dripping down from the bed 12 while leaving sufficient open space in the collector for vapor to rise.

[0048] All layers 13 and 13' of the two structured packed beds 12 and 12' consist solely of structured cross-channel packing elements 14, each having the same height H and the same specific surface area. To achieve both high mass transfer efficiency (even when operating at pressures above 10 bar) and relatively low pressure drop in the mass transfer tower 10, each structured cross-channel packing element 14 has a height H of 50 to less than 150 mm, and most preferably 75 to 110 mm, and a specific surface area of ​​60 to 500 mm. 2 / m 3The specific surface area. This solution is based on the surprising discovery that if the mass transfer tower 10 contains one or more structured packed beds 12, 12′, it can operate with high quality transfer efficiency and low pressure drop even at pressures of at least 6 bar and even greater than 10 bar or even greater than 15 bar, wherein the one or more structured packed beds 12, 12′ are composed of or at least primarily composed of materials with a specific surface area of ​​60 to 500 m². 2 / m 3 The structured cross-channel packing element 14 has a specific surface area and a height H of 50 to less than 150 mm. The inventors of this patent application believe that by shortening the height H of the structured cross-channel packing element 14, backmixing of the two phases flowing through the mass transfer tower 10 can be significantly reduced, and particularly axial backmixing, even if and especially if the mass transfer tower 10 is operating at a pressure greater than 10 bar. This is believed to be because by reducing the height H of the cross-channel packing element 14, a considerably long flow path within a known structured cross-channel packing element is interrupted or shortened.

[0049] During operation of distillation column 10, the gas, as the light phase, rises from the bottom to the top, while the liquid, as the heavy phase, descends countercurrently from the top to the bottom. More specifically, the liquid is substantially uniformly distributed by distributor 16 across the cross-section of the structured packed bed 12 and drips downwards along the surface of the sheets of the structured cross-channel packing element 14. Open spaces filled with gas are provided between the different sheets of the structured cross-channel packing element 14, providing a path for the gas to rise when driven by a pressure gradient. By allowing the liquid to diffuse across the surface of the sheets of the structured cross-channel packing element 14, a large interface is created between the two phases, thereby establishing effective heat and mass transfer between the liquid and gas at the interface. At the bottom of bed 12, the liquid is collected in collector 20 and guided downwards via conduit 22 to distributor 16' above the second bed 12'.

[0050] Figures 2a to 2b A structured cross-channel packing element 14 is shown for use in structured packed beds 12, 12′ according to the invention. The structured cross-channel packing element 14 is assembled from a plurality of corrugated sheets 24, 24′, which are parallel and in contact with each other. The structured cross-channel packing element 14 has a height H of 50 to less than 150 mm, and most preferably 75 to 110 mm, and a specific surface area of ​​60 to 500 m². 2 / m 3 .

[0051] The corrugated metal sheets 24, 24' are secured to each other, for example, by means of a plurality of rods (not shown) penetrating the corrugated sheets 24, 24' through a longitudinal section perpendicular to the corrugated sheets 24, 24'. The rods are secured to the first and last corrugated sheets by means of washers and nuts, or by the bent rods, or by any other means (not shown). Each corrugated sheet 24, 24' includes a plurality of alternately oriented peaks 26 and valleys 28, wherein adjacent corrugated sheets 24, 24' are oriented such that the corrugations 26, 28 of adjacent corrugated sheets 24, 24' intersect the corrugations 26, 28 of corrugated sheets 24, 24' extending obliquely relative to the longitudinal direction V in a cross-shaped manner, thereby forming a series of intersecting oblique channels 30. More specifically, the angle α between each peak 26 and each valley 28 relative to the longitudinal direction V is 10° to 60°, preferably 20° to 50°, and most preferably 25° to 47°, wherein the peaks 26 and valleys 28 of adjacent corrugated sheets 24, 24′ are oriented in opposite directions. Channels 30 define a maximum distance, such as, for example, 20 mm, between adjacent corrugated sheets 24, 24′. These channels 30 actively influence the flow of gas and liquid phases within the structured cross-channel packing element 14 and facilitate mass transfer between phases. That is, the gas and liquid phases contact each other within the channels 30 of the structured cross-channel packing element 14, thus promoting mass and heat transfer between phases. More specifically, as liquid flows downward through the mass transfer tower, the rising gas contacts the liquid present on the surfaces of the corrugated sheets 24, 24′ defining the channels 30. In summary, the lighter phase flows through the open spaces or channels 30 respectively. This results in particularly efficient mass and energy transfer between the lighter and heavier phases. Furthermore, the cross-shaped arrangement of channel 30 results in an optimal distribution of phases from left to right.

[0052] Figure 3 A partial view of the structured cross-channel packing element 14 used in the structured packing beds 12, 12′ according to an alternative embodiment of the invention is shown. Figure 3 The structured filler element 14 is similar to Figures 2a to 2bThe structured filler element shown differs in that the corrugated sheets 24, 24' do not include linearly extending peaks and valleys. Instead, the peaks 26, 26' and valleys of the corrugated sheets 24, 24' are curved in the end regions or portions 33, 33', respectively, so as to extend substantially vertically in the end regions 33, 33' of the corrugated sheets 24, 24'. The end regions are the uppermost and lowermost regions 33, 33' of the corrugated sheets 24, 24' extending 30%, preferably 25%, more preferably 20% or less from the upper and lower edges of the corrugated sheets 24, 24' along the length of the uppermost and lowermost edges, respectively, said length being along the longitudinal direction V of the corrugated sheets 24, 24'. Each end region 33, 33' may have peaks 26, 26' and valleys with heights different from the peaks and valleys of the central region. The central region is the area of ​​the corrugated sheet 24, 24' between the two end regions 33, 33'. Features such as different heights or bends may exist only in the two end regions 33, 33' of the corrugated sheet 24, 24'. The structured cross-channel packing element has a height H of 50 to less than 150 mm, and most preferably 75 to 110 mm, and a specific surface area of ​​60 to 500 m². 2 / m 3 .

[0053] exist Figure 3 In the diagram, the solid line depicts the peak 26 of the corrugated portion in the surface of the corrugated sheet 24 presented to the observer, while the dashed line 26′ depicts the peak of the corrugated portion in the corresponding surface of the corrugated sheet 24′ immediately following the corrugated sheet in the view. By bending the end regions 33, 33′ to extend substantially vertically in the end regions 33, 33′ of the corrugated sheets 24, 24′, the flow resistance of the end regions 33, 33′ of the corrugated sheets 24, 24′ is reduced compared to the flow resistance of the region located between the end regions 33, 33′ of the corrugated sheets 24, 24′. This results in a reduction in pressure loss of the structured packing element.

[0054] List of reference numerals and abbreviations

[0055] 10. Mass transfer column / distillation column

[0056] 12, 12′ Structured packed bed

[0057] 13, 13′ Layers of structured packed bed

[0058] 14 Structured cross-channel packing elements

[0059] 16, 16′ Distributor

[0060] 18 Holding device

[0061] 20 collectors

[0062] 22 Pipelines

[0063] 24, 24′ Corrugated Sheets

[0064] 26. Peaks of corrugated sheets

[0065] 26′ Peaks of adjacent corrugated sheets

[0066] 28 Tanibe

[0067] 30 lanes / open area

[0068] 33, 33′ End areas of corrugated sheet

[0069] H. Height of the structured cross-channel packing element

[0070] V represents the longitudinal direction, which is usually the vertical direction.

[0071] α The angle between each peak and each valley relative to the longitudinal direction

Claims

1. A structured packed bed (12, 12') for mass transfer and / or heat exchange between a first fluid phase and a second fluid phase, wherein the tower (10) for mass transfer and / or heat exchange is designed to operate at a pressure of at least 6 bar, wherein the structured packed bed (12, 12') comprises at least two layers (13, 13'), wherein the at least two layers (13, 13') are vertically stacked on top of each other, wherein each of the layers (13, 13') comprises at least one structured cross-channel packing element (14) having a diameter of 200 to 400 m. 2 / m 3 The specific surface area and height of 70 to 120 mm, wherein at least 50% of all structured cross-channel filler elements (14) are blocks, wherein each block comprises a plurality of sheets (24, 24') having periodically deformed portions, wherein the sheets (24, 24') are arranged parallel to each other and in contact in the longitudinal direction (V) such that an open space (30) is provided between them extending from one end of the sheets (24, 24') to the opposite end of the sheets (24, 24'), wherein the open space (30) is defined by periodically deformed portions, wherein adjacent sheets (24, 24') are oriented such that the periodically deformed portions of adjacent sheets (24, 24') intersect each other in a cross-shaped manner, wherein, At least one of the structured cross-channel packing elements (14) of layer (13, 13') is rotated 70° to 110° relative to at least one of the structured cross-channel packing elements (14) of adjacent layer (13, 13'), and wherein the structured packing bed (12, 12') has a circular cross-section and the diameter of the structured packing bed (12, 12') is at least 1 m.

2. The structured packed bed (12, 12') according to claim 1, wherein, The height of the at least one structured cross-channel filler element (14) is 75 to 110 mm.

3. The structured packed bed (12, 12') according to claim 1 or 2, wherein, The specific surface area of ​​the at least one structural cross-channel packing element (14) is 250 to 350 m². 2 / m 3 .

4. The structured packing bed (12, 12') according to claim 1 or 2, wherein each of the at least two layers (13, 13') comprises one or more structured cross-channel packing elements (14), wherein all structured cross-channel packing elements (14) of the layers (13, 13') have substantially the same specific surface area, wherein substantially the same specific surface area means that each structured cross-channel packing element (14) of the layers (13, 13') has a specific surface area of ​​80% to 120% of the average specific surface area of ​​all structured cross-channel packing elements (14) of the layers (13, 13').

5. The structured packing bed (12, 12') according to claim 4, wherein each structured cross-channel packing element (14) of the layer (13, 13') has a specific surface area of ​​90% to 110% of the average specific surface area of ​​all structured cross-channel packing elements (14) of the layer (13, 13').

6. The structured packing bed (12, 12') according to claim 5, wherein each structured cross-channel packing element (14) of the layer (13, 13') has a specific surface area of ​​95% to 105% of the average specific surface area of ​​all structured cross-channel packing elements (14) of the layer (13, 13').

7. The structured packing bed (12, 12') according to claim 6, wherein each structured cross-channel packing element (14) of the layer (13, 13') has a specific surface area of ​​98% to 102% of the average specific surface area of ​​all structured cross-channel packing elements (14) of the layer (13, 13').

8. The structured packing bed (12, 12') according to claim 1 or 2, wherein each of the at least two layers (13, 13') comprises one or more structured cross-channel packing elements (14), wherein all structured cross-channel packing elements (14) of the layers (13, 13') have the same specific surface area.

9. The structured packing bed (12, 12') according to claim 1 or 2, comprising 2 to 30 layers (13, 13').

10. The structured packing bed (12, 12') according to claim 9, comprising 8 to 25 layers (13, 13').

11. The structured packing bed (12, 12') according to claim 10, comprising 12 to 20 layers (13, 13').

12. The structured packed bed (12, 12') according to claim 1 or 2, wherein, The periodic deformation portion is a corrugated portion comprising a plurality of alternatingly oriented peaks (26, 26') and valleys (28, 28'), wherein the peaks (26) of the sheet (24) contact the valleys (28') of the adjacent sheet (24'), and the valleys (28) of the sheet (24) contact the peaks (26') of the adjacent sheet (24), wherein the adjacent sheets (24, 24') are oriented such that the peaks (26, 26') and valleys (28, 28') of the adjacent sheets (24, 24') intersect with the peaks (26, 26') and valleys (28, 28') of the sheet (24, 24') extending obliquely relative to the longitudinal direction (V) in a cross-shaped manner.

13. The structured packed bed (12, 12') according to claim 12, wherein, The angle (α) between each of the peaks (26, 26') and each of the valleys (28, 28') and the longitudinal direction (V) is 10° to 60°, wherein the peaks (26, 26') and valleys (28, 28') of adjacent sheets (24, 24') are oriented in opposite directions.

14. The structured packed bed (12, 12') according to claim 13, wherein, The angle (α) is between 20° and 50°.

15. The structured packed bed (12, 12') according to claim 14, wherein, The angle (α) is between 25° and 47°.

16. The structured packed bed (12, 12') according to claim 13, wherein, The peaks (26, 26') and valleys (28, 28') of the corrugated sheet (24, 24') are curved in one or both of the end regions (33, 33') so as to extend substantially along the longitudinal direction (V) in the end regions (33, 33') of the corrugated sheet (24, 24'), wherein substantially along the longitudinal direction (V) means that the end angle between the peaks (26, 26') or valleys (28, 28') and the longitudinal direction (V) is less than the angle (α) between each of the peaks (26, 26') and each of the valleys (28, 28') and the longitudinal direction (V), wherein the end regions (33, 33') are the uppermost and lowermost regions (33, 33') of the corrugated sheet (24, 24'). 33'), the uppermost region and the lowermost region extend 30% from the upper edge and lower edge of the corrugated sheet (24, 24') along the length of the corrugated sheet (24, 24').

17. The structured packed bed (12, 12') according to claim 16, wherein, The end angle is less than -10 to +10°.

18. The structured packed bed (12, 12') according to claim 17, wherein, The end angle is less than -5 to +5°.

19. The structured packed bed (12, 12') according to claim 18, wherein, The end angle is less than -2 to +2°.

20. The structured packed bed (12, 12') according to claim 16, wherein, The uppermost and lowermost regions extend 25% from the upper and lower edges of the corrugated sheet (24, 24') along the length of the corrugated sheet (24, 24').

21. The structured packed bed (12, 12') according to claim 20, wherein, The uppermost and lowermost regions extend from the upper and lower edges of the corrugated sheet (24, 24') by 20% or less along the length of the corrugated sheet (24, 24').

22. The structured packed bed (12, 12') according to claim 1, wherein, At least 50% of all structured cross-channel packing elements (14) of layer (13, 13') are rotated 70° to 110° relative to adjacent structured cross-channel packing elements (14) of adjacent layers (13, 13') of the structured packing bed (12, 12').

23. The structured packed bed (12, 12') according to claim 22, wherein, At least 75% of all structured cross-channel packing elements (14) of the layer (13, 13') are rotated 70° to 110° relative to the adjacent structured cross-channel packing elements (14) of the adjacent layer (13, 13') of the structured packing bed (12, 12').

24. The structured packed bed (12, 12') according to claim 23, wherein, At least 90% of all structured cross-channel packing elements (14) of layer (13, 13') are rotated 70° to 110° relative to adjacent structured cross-channel packing elements (14) of adjacent layers (13, 13') of the structured packing bed (12, 12').

25. The structured packed bed (12, 12') according to claim 24, wherein, At least 95% of all structured cross-channel packing elements (14) of the layer (13, 13') are rotated 70° to 110° relative to the adjacent structured cross-channel packing elements (14) of the adjacent layer (13, 13') of the structured packing bed (12, 12').

26. The structured packed bed (12, 12') according to claim 25, wherein, 100% of all structured cross-channel packing elements (14) of layer (13, 13') are rotated 70° to 110° relative to adjacent structured cross-channel packing elements (14) of adjacent layer (13, 13') of the structured packing bed (12, 12').

27. The structured packed bed (12, 12') according to any one of claims 22 to 26, wherein, The structured cross-channel packing element (14) of layer (13, 13') is rotated 80° to 100° relative to the adjacent structured cross-channel packing element (14) of the adjacent layer (13, 13') of the structured packing bed (12, 12').

28. The structured packed bed (12, 12') according to claim 27, wherein, The structured cross-channel packing element (14) of layer (13, 13') is rotated 85° to 95° relative to the adjacent structured cross-channel packing element (14) of the adjacent layer (13, 13') of the structured packing bed (12, 12').

29. The structured packed bed (12, 12') according to claim 28, wherein, The structured cross-channel packing element (14) of layer (13, 13') is rotated 88° to 92° relative to the adjacent structured cross-channel packing element (14) of the adjacent layer (13, 13') of the structured packing bed (12, 12').

30. The structured packed bed (12, 12') according to claim 1 or 2, wherein, The structured packing bed (12, 12') has a diameter of at least 1.5 m.

31. The structured packed bed (12, 12') according to claim 30, wherein, The structured packing bed (12, 12') has a diameter of 1.5 to 12 m.

32. The structured packed bed (12, 12') according to claim 31, wherein, The structured packing bed (12, 12') has a diameter of 1.5 to 6 m.

33. A mass transfer and / or heat exchange tower (10) comprising at least one structured packed bed (12, 12') according to any one of claims 1 to 32.

34. The mass transfer and / or heat exchange tower (10) according to claim 33, wherein, The mass transfer and / or heat exchange tower (10) has a circular cross-section, and the inner diameter of the mass transfer and / or heat exchange tower (10) is at least 1 m.

35. The mass transfer and / or heat exchange tower (10) according to claim 34, wherein, The inner diameter is at least 1.5m.

36. The mass transfer and / or heat exchange tower (10) according to claim 35, wherein, The inner diameter is 1.5m to 12m.

37. The mass transfer and / or heat exchange tower (10) according to claim 36, wherein, The inner diameter is 1.5m to 6m.

38. A method for mass transfer and / or heat exchange, wherein, At least two fluids are directed through a mass transfer and / or heat exchange tower (10) according to any one of claims 33 to 37, wherein the mass transfer and / or heat exchange tower (10) operates at a pressure of at least 6 bar.

Images