Device for the optimal handling of structured wire packings for process engineering applications

Abstract

Device (1) for improving the assembly and disassembly of column internals based on structured wire packings / structured cartridges (6).:

Description

[0001] Unstructured packings have been used for over 100 years and structured packings for about 50 years in chemical and thermal process engineering, wastewater and exhaust air purification in special heat and mass transfer columns.

[0002] In this technology area, separation processes such as absorption, distillation, rectification, and extraction are very frequently used. To increase the mass and / or heat exchange surface area between a gaseous or vaporous phase and a liquid or liquid-liquid phases within a separation column, internals such as packings and / or structured packings are positioned. The purpose of these internals is to distribute the phases evenly across the column cross-section and to achieve a maximum liquid surface area for mass and heat exchange.

[0003] Packed columns are designed for continuous mass and heat exchange and are not equipped with individual trays, as is the case with tray columns, but rather feature a continuous layer of packing material extending the entire height of the column. Depending on the application, the packing material can be formed from a wide variety of geometries, with specific surface finishes, and made of various materials (metal, ceramic, plastic). The most common packing materials used are Raschig rings, Pall rings, or saddle-shaped packings. The primary objective of the process is to ensure a continuous and consistent flow of material to the packing surfaces in order to achieve the highest possible surface area and thus long residence times between the gas or vapor and the liquid.Uniform application across the column's cross-section and distribution of the liquid throughout the entire column are considered very demanding requirements that remain the focus of optimization efforts in research and development.

[0004] It is known that in packed columns, despite uniform feeding, the flowing liquid, due to the high degree of voids at the edge, always flows towards the column wall, and the core of the packing layer is either not exposed at all or only partially exposed. This detrimental effect is even more pronounced with decreasing liquid exposure. It should be noted that the so-called creep flows or stream formations, caused by edge permeation, may represent a narrow marginal zone, but when considered in relation to the column's circumference, they can occupy a large proportion of the column's cross-sectional area. This phenomenon is also referred to as maldistribution in column technology.

[0005] The effects of edge penetration and channel formation, frequently occurring in packed columns, with subsequent axial and radial maldistribution, often have such drastic negative consequences that the required and guaranteed separation efficiency of a column is not achieved. Almost all known failures of packed columns can be attributed to maldistribution [M. Gann, Chem. Ing. Tech. 64 (1992) 1, pp. 6-16].

[0006] Maldistribution significantly reduces mass transfer in packed columns. Therefore, according to current technology, depending on the column size, the packing is interrupted every 2-4 m, the liquid is collected at the edge, and then redistributed. This redistribution procedure is very complex because additional receiving grates, collection devices, and liquid distribution systems are required. These multiple measures dramatically increase the height of the packed columns, and furthermore, the cost of the respective additional receiving, collection, and distribution devices is usually higher than the packing itself.

[0007] It is also known that the separation efficiency of packed columns is quite low in the lower pressure range. It improves continuously as the flooding point is approached. This is because a pronounced turbulent spray and bubble layer forms within the packing, which positively influences mass transfer. However, the improvement in separation efficiency by approaching the flooding point can only be achieved by increasing the pressure drop. A disadvantage of this is that packings used in columns already exhibit high pressure drops due to their inherently unfavorable flow geometry (resistance coefficient).

[0008] Within chemical and thermal process engineering, as well as in other demanding technological fields, devices equipped with defined and reproducible contact surfaces have been increasingly used for several decades. These so-called "structured packings," due to their advantageous properties such as low pressure drop, high efficiency, and performance, have replaced established packed bed materials in many areas. Together with optimized versions of this type, they currently represent the state of the art.

[0009] Due to their low pressure drop, structured packings are ideally suited for applications involving volatile chemicals. They also allow for higher throughput rates and, consequently, smaller column dimensions than tray or packed columns. Furthermore, there is no risk of fluidized bed formation or material discharge when the flooding point is exceeded.

[0010] However, the production of conventional structured packings is considerably more expensive and complex than the production of loose fill materials. The article "Prozesstechnik Online" from December 11, 2015, reports that 10,000 to 20,000 welding points per cubic meter are required for the production of structured packings, depending on the application.

[0011] As already claimed in utility model applications DE 20 2022 001 756 U1 and DE 20 2024 001 869 U1, various uniform geometries are available that can be constructed much more easily compared to current structured packings. Surprisingly, it has been shown that structured metal wire devices (wire packings), similar to conventional structured packings, can be successfully used in columns for various applications. However, they offer significant advantages compared to these, namely that their manufacture is much simpler. Furthermore, to achieve a large exchange surface area, the wires can be repeatedly formed into a wide variety of geometries with virtually any diameter, length, gap size, and specific surface area.The wires can be arranged horizontally, vertically, or at specific angles within the column. To achieve very long lengths, these tubular metal wire devices can be connected end-to-end. In summary, these novel packing structures, with their versatility, are a suitable means of meeting a wide range of requirements regarding diameter and column length, and are considerably cheaper to produce and replace (they can simply be pulled out of the reactor). Furthermore, they tend to offer a lower pressure drop for the same surface area than comparable packings with similar void ratios and specific surface areas, and a significantly lower pressure drop than packed bed packings.

[0012] The following table provides a comparison between fillers, structured packings, and vein packings: Filler Structured metal packing Structured vein packing (Lessmann) Pressure loss -- ++ ++ Marginal -- 1) + ++ Stream formation -- 1) + + Production - 2) -- 3) ++ handling + - 4) ++ Scalability + + ++ Additional liquid distributor necessary necessary integrated liquid collector necessary necessary no (no marginal walks) Support systems necessary necessary no (self-locking) Material usage high high low Integrating existing systems welding welding Yes (self-locking) Electrically heated no no Yes 1) Edge flow and stream formation (maldistribution) are major problems in exchange columns filled with random packing. In practice, the liquid is collected at the edges every 3 to 4 meters and redistributed within the column. However, once stream formation has occurred, the liquid preferentially flows out of these areas without contact with gas. 2) A Pallring 15x15x0.4 and 360 m is used as a basis for comparison. 2 / m 3 Application: It should be noted that approximately 240,000 Pall rings are required per cubic meter. Considering that exchange columns can reach heights of up to 100 m and diameters of 15 to 20 m, it is easy to estimate the required quantity. 3) Structured packings of types X and Y are known. Type X has a 60° angle, while type Y has a 45° angle. The height ranges from 200 to 500 mm. Precisely fitting modules must be manufactured for each diameter. 4) From 3) it can be deduced that structured packings require careful design and precise assembly of the X or Y segments to ensure consistent performance. Malfunctions caused by improperly aligned modules would lead to channeling and poor fluid distribution.

[0013] An essential part of the invention is that the upper and lower holders of the wire packing consist of trays which are perforated for media exchange like a conventional perforated bottom in columns and which have a rim for guiding the wires.

[0014] The conductors are guided in a form-fitting and force-fit manner (by compression) at the top and bottom. Both shells are connected by a rigid rod that runs centrally through the conductor packing. This results in easily handled and freely scalable "cartridges" for the conductor packing. Because the conductors, due to their corrugation, act like many individual springs, they create a bulge that extends beyond the diameter of the shells. This means that, in an unloaded / uninstalled state, the conductors have a diameter that exceeds the inner diameter of the column / shells. When installed, this results in a contact pressure of the conductors against the column's inner wall, effectively preventing edge penetration. The design, with the conductor ends compressed into the shells, allows for easy installation and removal of the cartridges by simply twisting the upper shell against the lower one.The longer path for the individual conductors between the upper and lower shells, resulting from the twisting motion, stretches the individual conductors and pulls the entire conductor packing together around the circumference. This twisting and subsequent stretching of the conductors eliminates any bulging, thus preventing resistance during assembly and disassembly. Assembly and disassembly are therefore significantly easier than with loosely packed rings or structured packings. Standard stainless steel threaded rods are used to attach the shells.

[0015] A further advantage of this arrangement is the self-locking of the larger diameter of the packing within the columns. This eliminates the need for additional receiving and distribution devices for the liquid phase, and, not least, significantly reduces the column height. This means that the otherwise essential holding devices for loose packing and conventional packed columns can be completely omitted. It is important to note that the support and hold-down grids otherwise required necessitate very careful pre-selection, as malfunctions can adversely affect the fluid dynamics. By avoiding the highly detrimental edge penetration and channeling, as well as eliminating additional internal components, a very uniform liquid distribution within the columns is achieved.

[0016] The objective of the invention is therefore to improve the mass and heat transfer within columns used in chemical and thermal process engineering as well as in exhaust gas purification. This objective is achieved by equipping the columns with tubular structured metal wire devices as packing internals, which function as exchange packing, and by significantly simplifying their installation through prior twisting of the wire packing.

[0017] It is also known that all columns require droplet separators at the gas outlet as a safety device to prevent droplet carryover, particularly during operation at the limit, such as at the stagnation and flooding points. A disadvantage is that, for them to function properly, they require very high specific surface areas and flow velocities, thus causing significant and costly pressure drop contributions. Because these novel structured metal wire packings according to the invention can be easily provided with very high specific surface areas and comparatively low pressure drop values, they are also suitable as droplet separators in columns.

[0018] Further advantages, details and features of the invention will become apparent from the following description and from the drawings, which show: Fig.1 a simplified sketch of the structured wire packing according to the invention, in this case the upper or lower holder with perforated plates. Fig. 2 A simplified illustration of the wire packing with upper and lower support rings before installation and before twisting. Fig. 3 Simple sketches of the wire packing with upper and lower support rings before installation and after twisting. Fig. 4 A simplified illustration of the wire packing with upper and lower support ring after installation and after untangling the twist.

[0019] In Fig.Figure 1 shows the device according to the invention for manipulating novel wire packings. Figure 2 shows the upper and lower shells, which have a U-shaped cross-section in section. The legs of the U (2) compress the individual wires (6) so that they are firmly bound at the top and bottom. The shell bottoms are perforated (3) to allow media to pass through. The guide rod is mounted in the center.

[0020] In Fig.Figure 2 shows the entire cartridge structured according to the invention before assembly, depicted here unstwisted and not installed. The individual strands (6) are corrugated and, outside the crimp in the upper (5) and lower shells (7), form a bulge which is resilient and allows the diameter to increase to values ​​larger than that of the shells or the column's inner diameter. By twisting (4) the upper shells (5) relative to the lower shell (7), the cartridge is tensioned for assembly and disassembly.

[0021] In Fig.Figure 3 shows the entire cartridge structured according to the invention during assembly, which is shown here in the assembly / disassembly state (8). By rotating the upper shell (5) relative to the lower shell (7), the path for the individual conductors (6) becomes longer, so that these conductors, which are designed like individual springs due to their corrugation, are stretched (9) and the cartridge loses its bulge. Thus, the conductors do not protrude beyond the diameter of the shells, and assembly / disassembly can be easily carried out by pushing / pulling in / out of the column (12). The middle rod serves both to pull the cartridge out of the column and to absorb the torque during the rotation of the upper shell relative to the lower one.

[0022] In Fig.4 The entire “cartridge” structured according to the invention is sketched in the installed state, which, by turning (10) the upper shell (5) back relative to the lower shell (7), relaxes the individual (6) veins so that they press against the column inner wall (12) by means of their spring construction and prevent edge penetration.

[0023] The parameters regarding material, wire thickness, geometry and process-related parameters (gap ratio, specific surface area) can be freely selected within a wide range.

[0024] Of course, the examples described can be modified and supplemented in many ways without departing from the basic concept of the invention. Naturally, these devices can be used in both absorbers and desorbers.

[0025] Naturally, the invention also relates to the method for optimizing the handling of packed columns by using structured metal wire devices as ordered packing for process engineering applications. Reference symbol list 1 Mounting device for structured wire packing 2 Holding devices for wires (top & bottom) 3 perforated sheet metal 4 Structured wire packing before installation (untwisted) 5 Holding device at the top 6-core wire 7 Lower retaining device 8 Structured wire packings ready for assembly (twisted) 9 Twisted veins 10 Built-in wire packing 11. Compression packing (prevention of edge penetration) 12 exchange column QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 20 2022 001 756 U1

[0011] DE 20 2024 001 869 U1

[0011] Cited non-patent literature

[0000] M. Gann, Chem. Ing. Tech. 64 (1992) 1, pp. 6-16

[0005]

Claims

[1] Device (1) for improving the assembly and disassembly of column internals based on structured wire packings / structured cartridges (6).: [2] Device according to claim 1 characterized by , that an upper shell (5) and a lower shell (7) accommodate the vein packing (6) and these shells are perforated (3)- [3] Device according to the preceding claim characterized by , that the upper shell (5) is rotated relative to the lower shell (7) before the packing is installed. [4] Device according to the preceding claims characterized by , that by rotating the upper shell (5) relative to the lower shell (7) a simple installation of the twisted wire packing into the packing column (12) is possible. [5] Device according to the preceding claims, characterized by, that after the tensioned wire packing (6) is installed in the column (12) by turning (10) the upper shell (5) back relative to the lower shell (7) the individual (6) wires relax again, so that they press against the inner wall of the column (12) by means of their spring construction and prevent edge penetration. [6] Device according to the preceding claims, characterized by , that by installing the tensioned wire packing (9) into the column (12) and subsequently relaxing it after installation (10), the wire packing is self-supporting.

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