CN115301192A - Centrifugal flow type vertical structured packing - Google Patents

Abstract

The invention provides a centrifugal flow vertical structured packing, comprising: a first support body, a second support body, and a plurality of filler monomers, wherein the filler monomers are composed of a wire with a certain cross-sectional shape and a certain screw diameter and The pitch is coiled, and the resulting structure is similar to a spring that is stretched to a certain extent. The central axis of the filler monomer is perpendicular to the horizontal plane, and the central axes of the plurality of filler monomers are parallel. The plurality of filler monomers are regularly arranged at a preset distance. The invention uses the helical gap to distribute liquid under the action of capillary force, changes the zigzag gas phase channel of the traditional corrugated structured packing, and further reduces the pressure drop of the gas phase when passing through the packing; the centrifugal channel increases the liquid phase from top to bottom. It can effectively improve the production load of rectification and absorption towers to achieve separation efficiency, and at the same time ensure the engineering requirements of long-term operation.

Description

A Centrifugal Flow Vertical Structured Packing

technical field

The invention belongs to the field of chemical tower internals equipment, and in particular relates to a centrifugal flow type vertical structured packing.

Background technique

Packed tower is a very important gas-liquid mass transfer equipment, which has the advantages of high separation efficiency, large flux, pressure drop, and small liquid holdup, and has advantages in vacuum operation, separation of heat-sensitive substances, and energy saving. Therefore, it has been widely used in chemical industry, oil refining, light industry, pharmaceutical and atomic energy industry. After more than 50 years of development, structured packing with high efficiency and low resistance has been widely used in packed towers. Most of the structured packings are based on the corrugated staggered structure, mainly metal corrugated plates and wire mesh corrugated structured packings, which are obtained through partial modification and performance upgrade. The direction of transformation and upgrading mainly includes improving the effective mass transfer area and self-distribution capacity, improving the liquid renewal frequency and anti-clogging performance, and reducing the gas resistance and amplification effect.

However, the zigzag-shaped gas-liquid channel makes the reduction of the operating pressure drop of the corrugated plate-type structured packing limited, and its self-distribution performance has not been improved. Vertical structured packing is a general term for column packing with vertical gas phase channels, specifically grid packing, fine line packing, tube packing and so on. This type of packing often has low gas pressure drop and good self-distribution performance, but its separation efficiency is far lower than that of traditional corrugated plate type structured packing, mainly because the vertical channel makes the liquid flow through its surface. Dwell time is greatly reduced. Retaining the structural basis of vertical structured packing and improving the residence time of liquid on the surface of the packing is the fundamental development direction of vertical structured packing.

Contents of the invention

The object of the present invention is to overcome the deficiencies in pressure drop, processing capacity and liquid self-distribution performance of the above traditional structured packing, and provide a centrifugal flow vertical type structured packing with good liquid self-distribution performance and high mass transfer efficiency.

The technical scheme that realizes the object of the present invention is as follows:

A centrifugal flow type vertical structured packing, comprising: a first support body, a second support body, and a plurality of filler monomers, the filler monomers are formed by coiling a wire with a certain cross-sectional shape with a certain screw diameter and pitch , forming a structure similar to a spring stretched to a certain extent. The filler monomer has a first end and a second end, the first end is connected to the first support body, the second end is connected to the second support body, and the central axis of the filler monomer It is perpendicular to the horizontal plane, and the central axes of multiple filler monomers are parallel. The plurality of filler monomers are regularly arranged at a preset distance. The minimum value of the predetermined distance is limited to the fact that the filler monomers do not contact each other.

Multiple packing monomers are the main areas where the gas-liquid mass transfer and heat transfer process takes place. When performing rectification or absorption operations, the liquid is filled with the gap formed by the helix, and forms a semi-enclosed channel along it to move downwards and do spiral flow; the gas passes through the inner and outer spaces of the vertical tube to make reverse contact with the liquid film and The heat transfer process takes place.

The first support body includes evenly distributed air caps, downholes and wire fixing mechanisms. The main function is to fix and limit the upper end of the helical monomer and distribute the liquid on the upper part.

The first support body can adopt a dedicated liquid distributor, preferably a siphon type liquid distributor.

The second support body includes air holes and a wire fixing mechanism. The main function is to fix and limit the lower end of the helical monomer. A snap-on fastening mechanism is preferred.

Further, the central axis of the packing monomer is parallel to the central axis of the rectification tower or the absorption tower, and the center points of each packing monomer are arranged in a regular triangle, square or rhombus in the radial direction of the rectification tower or the absorption tower.

Further, the cross-section of the wire used in the centrifugal flow type vertical structured packing can be in any shape, the wire of the filler monomer is solid or hollow, and the hydraulic diameter of the wire is 0.5-5 mm.

Further, the helical coil formed by the coiled wire of the filler monomer has a helix diameter of 2-100 mm and a helix pitch of 0.5-4 mm.

Further, the wires coiled to form the helical coil are 1-4 strands. When multiple strands of wires are selected for coiling, the wires are arranged in parallel to ensure a constant screw diameter and pitch.

Further, the wire is selected from all materials such as steel, plastic or ceramics that can be coiled, cut and cast to form a helical coil.

The liquid flows through the packing from top to bottom, and two different flow patterns will appear by changing the pitch. When the pitch is small, the liquid will flow down along the spiral gap in the form of a liquid film, showing a continuous film flow; when the pitch After increasing to a certain value, the liquid film ruptures and condenses to form liquid droplets to flow downward. This flow form is extremely unstable, and the liquid droplets may directly drop or even fly out.

The liquid film in the packing spiral gap is also called liquid bridge. The liquid bridge is an important feature of centrifugal flow vertical structured packing, and it is also a place for efficient mass and heat transfer between gas and liquid. The upper and lower ends of the liquid bridge formed by the spiral gap are attached to the surface of the spiral to connect the parallel spirals. The inner and outer sides of the liquid bridge are exposed to the gas environment and contact with the gas to form a free surface, so that effective mass transfer occurs heat transfer process.

Centrifugal flow type vertical structured packing has a hollow vertical structure. The liquid flows on the surface of the packing under the constraint of the spiral, and the gas flows vertically on both sides of the packing. Reduced, and the inner and outer sides of the vertical packing are good gas-liquid contact places, have a larger mass transfer and heat transfer area, and perfectly solve the problems of packing cleaning and fouling. In addition, the optimized spiral can not only increase the contact area between the liquid and the surface of the spiral, but also reduce the amount of materials used. The spiral liquid phase channel increases the contact time between gas and liquid without affecting the gas phase flow, achieving the effect of enhancing mass transfer. The simple structure of centrifugal flow vertical structured packing makes it have superior liquid self-distribution ability.

Advantages and beneficial effects of the present invention:

The invention utilizes the helical gap to distribute the liquid under the action of capillary force, which changes the zigzag gas phase channel of the traditional corrugated structured packing, and further reduces the pressure drop of the gas phase when passing through the packing; the independent packing unit ensures the uniformity of the gas and liquid phases Distribution, the outside and inside of the filler are good gas-liquid contact places. Under the same specification, the gas-liquid contact area doubles, which is more conducive to mass and heat transfer. The centrifugal channel increases the liquid phase from top to bottom. The residence time can effectively increase the production load of the rectification and absorption tower to separate the efficiency, and at the same time ensure the engineering requirements of long-term operation. It also has significant advantages in improving efficiency and saving materials. Applicable to all rectification towers and absorption towers.

Description of drawings

Fig. 1 is the front view of the internal arrangement of centrifugal flow type vertical structured packing tower according to the embodiment of the present application;

Figure 2 is a partial three-dimensional view of a centrifugal flow type vertical structured packing monomer in an embodiment of the present application;

Fig. 3 is a top view of the inner layout of the centrifugal flow type vertical structured packing tower according to the embodiment of the present application;

Figure 4 is a schematic diagram of the flow of liquid on the centrifugal flow vertical structured packing of the embodiment of the present application;

Fig. 5 is the profile diagram of the static liquid bridge of the helical gap of the embodiment of the present application, wherein (a) is the side of the liquid bridge; (b) is the front of the liquid bridge;

Fig. 6 is a comparison diagram of different pitch liquid forms in the embodiment of the present application, wherein (a) pitch is 1.5mm, (b) pitch is 2.0mm, (c) pitch is 3.0mm;

Fig. 7 is a flow process diagram of tracer particles under the liquid bridge flow mode of the embodiment of the present application (pitch 2.0mm, screw diameter 14mm, liquid flow rate=80mL/min);

Figure 8 shows the shape of liquid bridges in the helical gap of fillers with different diameters according to the embodiment of the present application, (a) 12m in diameter, (b) 14mm in diameter, and 16mm in (c) diameter.

Wherein: 1 is the first support body, 11 is the gas lift cap, 12 is the downcomer hole, 2 is the filler monomer, 21 is the first end, 22 is the second end, and 3 is the second support body;

D is the screw diameter, θ is the inclination angle of the helix, W is the pitch, d is the diameter of the wire, and t is the distance between the central axes of the adjacent filler monomers;

Detailed ways:

The method and device provided by the present invention will be further described below in conjunction with the accompanying drawings.

As shown in FIG. 1 , a centrifugal flow type vertical structured packing includes: a first support body 1 , a second support body 3 , and a plurality of packing monomers 2 .

As shown in FIG. 2 , the filler monomer 2 is formed by coiling a wire with a certain cross-sectional shape with a certain diameter and pitch, and the formed structure is similar to a spring stretched to a certain extent. The filler monomer 2 has a first end 21 and a second end 22, the first end 21 is connected to the first support body 1, and the second end 22 is connected to the second support body 3, so The central axis of the filler monomer 2 is perpendicular to the horizontal plane, and the central axes of multiple filler monomers 2 are parallel. The plurality of filler monomers 2 are regularly arranged at a preset distance. The minimum value of the preset distance is limited to the fact that the filler monomers 2 do not contact each other.

The first support body 1 includes evenly distributed air lift caps 11 , downcomer holes 12 and a wire fixing mechanism. The main function is to fix and limit the upper end of the helical monomer and distribute the liquid on the upper part. The first support body 1 can adopt a dedicated liquid distributor, preferably a siphon type liquid distributor.

The second support body 3 includes air holes and a wire fixing mechanism. The main function is to fix and limit the lower end of the helical unit, and the buckle fixing method is preferred.

As a preferred embodiment, both the first end 21 and the second end 22 of the filler monomer 2 are a section of vertical straight rod coincident with the central axis. When installed in the rectification tower and the absorption tower, the first end 21 of the packing monomer 2 will be fixed with the center of the single riser cap 11 of the siphon liquid distributor through nesting, welding or bolting, and the second end 22 will be fixed with the The device is snap-fastened. After the installation is completed, the central axis of the filler monomer 2 is perpendicular to the horizontal plane.

As shown in FIG. 3 , the central axes of the filler monomers 2 are parallel to each other and arranged in an equilateral triangle. The distance between packing and monomer axis is generally 1.2-2 times the length of screw diameter 2, which is related to the processing capacity of rectification and absorption tower.

The cross-section of the wire rod used for centrifugal flow type vertical type structured packing can be in any shape, the wire rod of the filler monomer 2 is solid or hollow, the screw diameter of the filler monomer 2 and the number of strands of the spiral wire, the hydraulic diameter of the wire rod cross-section , The processing capacity of the tower is related to the interfacial tension of the system, and the setting range is 2-100mm. The pitch of the filler monomer 2 is mainly related to the surface tension of the liquid material, and the setting range is 0.5-4mm.

The wire rods coiled to form the helical coil are 1-4 strands. When multiple strands of wire rods are selected for coiling, the wire rods are arranged in parallel to ensure a constant screw diameter and pitch. The wire is selected from all materials such as steel, plastic or ceramics that can be coiled, cut and cast to form a helical coil.

As shown in Figure 4, when performing rectification or absorption operations, the liquid is filled with the gap formed by the wire rod to form a liquid film and moves downward; the gas is in reverse contact with the liquid film through the inner and outer spaces of the vertical tube from bottom to top and transmission occurs. mass heat transfer process.

Figure 5 shows the shape of the static liquid bridge in the helical gap of the centrifugal flow vertical structured packing. The liquid bridge is formed due to the existence of adhesion between the liquid and the solid surface. At this time, the cohesive force inside the liquid is smaller than that between the solid wall and the liquid. For adhesion, the solid surface is wetted. Since the upper and lower parallel spirals are not at the same horizontal position, but have a certain inclination angle, it can be seen from the front view that the liquid bridge has a tendency to slide forward. The liquid bridge is subjected to the resistance between solid and liquid, liquid and liquid in the direction of the helix and the component force of gravity in the direction of the helix, and the two cancel each other out, so the liquid bridge is in a static state. Due to the interaction between the pressure difference between the gas and the liquid and the surface tension of the liquid, the liquid molecules on the surface layer are subjected to a pulling force pointing to the inside of the liquid, and the macroscopic performance is that the periphery of the liquid bridge is concave inward. Due to the influence of gravity, the curvature of the upper and lower liquid bridges is not equal, and the curvature of the lower liquid bridge is slightly smaller than that of the upper part; for the boundary profile of the liquid bridge in the flow direction, the liquid is under the action of gravity and internal static pressure. The curvature of the front liquid bridge boundary profile is slightly smaller than that of the rear; for the liquid bridge boundary profile in the transverse direction, since the spiral is inclined inward, the curvature of the inner liquid bridge boundary profile is slightly smaller than that of the outer one. When analyzing the force of the entire liquid bridge and reconstructing the boundary contour, since the curvature difference of the upper and lower liquid bridges is very small, the curvature of the inner and outer liquid bridges is also very small, and the gap between the spirals is very small. In the case of ignoring gravity, The boundary of the liquid bridge can be approximately regarded as a symmetrical structure with top, bottom, inside, and outside respectively.

In order to explore the flow form of the liquid bridge in the helical gap of vertical structured packing in centrifugal flow, red polystyrene microspheres with an average particle size of 5 μm were used as tracer particles to characterize the flow form of the helical gap liquid bridge. Use a pipette gun to add a drop of tracer particle solution to the liquid bridge that flows stably in the helical gap, and the tracer particles will flow along with the liquid bridge. flow form, and intercepted 10 pictures of the position changes of the tracer particles on the spiral falling film structured packing at different times (Fig. 7). Through the slow playback of the image, it is found that the flow form of the tracer particles in the helical gap of the centrifugal flow type vertical structured packing is spirally descending along the direction of the helix, changing the liquid phase load and testing different specifications of the packing, the liquid bridge is a spiral decline. As shown in Figure 7, the drop height of the tracer particles is basically the same in the same time interval, but as the drop height increases, the tracer particles will gradually disperse on the flow path, and the longer the filler, the more significant this phenomenon is, indicating the liquid bridge The flow process in the spiral gap accelerates the spiral downward, which causes the distance between the previous particle and the next particle to become larger and larger, and the tracer particle cluster is dragged out. At the same time, the increase of the liquid bridge speed will lead to the increase of the centrifugal force, and the stability of the liquid bridge may be damaged, which is unfavorable to the packing. Therefore, the longer the packing is not the better.

The fillers with screw diameters of 12mm, 14mm, 16mm and pitch of 2.5mm were selected to explore the influence of filler diameter on the liquid bridge. As shown in Figure 8, the screw diameter has no significant effect on the formation of the liquid bridge, no matter how the screw diameter changes, The liquid can form a stable and continuous liquid bridge in the packing spiral gap. In addition, packing with spiral width of 2.5mm and 3.0mm, diameter of 14mm, and pitch of 2.5mm was selected to explore the influence of spiral width on the liquid bridge. It is found that the liquid can form a stable and continuous liquid bridge in the gap between the packing spirals with different spiral widths. As the liquid phase load increases, the filler liquid bridge with wider spirals is more stable, but the thickness of the liquid bridge will also increase. . In summary, the packing diameter and spiral width have no significant effect on the formation and flow of the liquid bridge, but the spiral width will affect the final liquid bridge thickness, thereby affecting the mass and heat transfer efficiency.

Example 1

Centrifugal flow type vertical structured packing wire is coiled by 1mm solid circular cross-section stainless steel wire, with a screw diameter of 10mm, a pitch of 1.5mm, and a packing height of 3m. It is arranged vertically in an equilateral triangle in a 300mm diameter rectification tower. Installed in parallel, the distance between the central axis is 15mm. The top of the packing is connected with the siphon liquid distributor, and the bottom is snapped and fixed with the fixing device. After the installation is completed, the central axis of each packing unit is perpendicular to the horizontal plane. Implement rectification separation with cyclohexane-n-heptane system, add the cyclohexane-n-heptane mixture with a molar ratio of 1:5 into the rectification tower reboiler, and perform total reflux operation. The rectification tower operating pressure is 1atm, the number of theoretical plates in the whole tower is 4, and the theoretical plate number of the wire mesh 350Y packing under the same operating conditions is 3.5.

Example 2

Centrifugal flow type vertical structured packing wire is coiled by 1mm solid circular cross-section stainless steel wire, with a screw diameter of 10mm, a pitch of 1.5mm, and a packing height of 3m. It is arranged vertically in an equilateral triangle in a 300mm diameter rectification tower. Installed in parallel, the distance between the central axis is 15mm. The top of the packing is connected with the siphon liquid distributor, and the bottom is snapped and fixed with the fixing device. After the installation is completed, the central axis of each packing unit is perpendicular to the horizontal plane. Implement rectification separation with ethanol-n-propanol system, add the ethanol-n-propanol mixture with a molar ratio of 1:3 into the rectification tower reboiler, and carry out total reflux operation. The rectification tower operating pressure is 1 atm, and the measured The theoretical plate number of the whole column is 3, and the theoretical plate number of the wire mesh 350Y packing is 2 under the same operating conditions.

Example 3

Centrifugal flow type vertical structured packing is made of cast iron into a 0.2mm*2mm solid rectangular cross-section spiral coil with a screw diameter of 14mm, a pitch of 2.5mm, and a packing height of 1.5m. It is arranged vertically and parallel in a square in a 600mm diameter absorption tower. Installation, the central axis spacing is 20mm. The top of the packing is connected with the siphon liquid distributor, and the bottom is snapped and fixed with the fixing device. After the installation is completed, the central axis of each packing unit is perpendicular to the horizontal plane. Carbon dioxide-water system is used to implement absorption separation, distilled water is fed from the top of the absorption tower at 200L/h, carbon dioxide is fed from the bottom of the absorption tower at 100m ² /h, distilled water and carbon dioxide carry out reverse contact absorption process in the absorption tower, absorbing The operating pressure of the tower is 1 atm, and the measured theoretical plate number of the whole tower is 2.5. Under the same operating conditions, the theoretical plate number of the wire mesh 350Y packing is 2.

Example 4

Centrifugal flow type vertical structured packing is made of cast iron into a 0.2mm*2mm solid rectangular cross-section spiral coil with a screw diameter of 14mm, a pitch of 2.5mm, and a packing height of 1.5m. It is arranged vertically and parallel in a square in a 600mm diameter absorption tower. Installation, the central axis spacing is 20mm. The top of the packing is connected with the siphon liquid distributor, and the bottom is snapped and fixed with the fixing device. After the installation is completed, the central axis of each packing unit is perpendicular to the horizontal plane. The carbon dioxide-ethanolamine system is used to carry out absorption and separation. The ethanolamine solution is fed from the top of the absorption tower at 200L/h, and the carbon dioxide is fed from the bottom of the absorption tower at 100m ² /h. The ethanolamine and carbon dioxide are subjected to reverse contact absorption process in the absorption tower. The operating pressure of the absorption tower is 1 atm, and the measured theoretical plate number of the whole tower is 3, and the theoretical plate number of the wire mesh 350Y packing under the same operating conditions is 2.

A centrifugal flow type vertical structured packing proposed by the present invention has been described through preferred embodiments, and those skilled in the art can obviously modify the structure and equipment described herein without departing from the content, spirit and scope of the present invention Or make appropriate changes and compositions to realize the technology of the present invention. In particular, it should be pointed out that all similar substitutions and modifications will be obvious to those skilled in the art, and they are all considered to be included in the spirit, scope and content of the present invention.

Claims (9)

1. A centrifugal flow vertical type structured packing, characterized in that, comprising: the first support body (1), the second support body (3), A plurality of filler monomers (2), the filler monomers (2) are coiled into a helical coil shape by a wire having a certain cross-sectional shape with a certain diameter and pitch, and the filler monomers (2) have a first end ( 21) and a second end (22), the first end (21) is connected with the first support body (1), and the second end (22) is connected with the second support body (3), The plurality of filler monomers (2) are regularly arranged at a preset distance, and the central axes of the plurality of filler monomers (2) are parallel. 2. The centrifugal flow vertical type structured packing according to claim 1, characterized in that, the first support body (1) comprises uniformly distributed lift caps (11), downcomer holes (12) and wire fixing mechanism. 3. The centrifugal flow vertical type structured packing according to claim 2, characterized in that the first support body (1) is a liquid distributor. 4. The centrifugal flow type vertical structured packing according to claim 1, characterized in that the second support body (3) includes air holes and a wire fixing mechanism. 5. centrifugal flow type vertical type structured packing according to claim 1, is characterized in that, the central axis of described packing monomer (2) is parallel with the central axis of rectification tower or absorption tower, each packing monomer (2) ) center points are arranged in an equilateral triangle, square or rhombus in the radial direction of the rectification tower or absorption tower. 6 . The centrifugal flow type vertical structured packing according to claim 1 , characterized in that, the wire of the filler monomer ( 2 ) is solid or hollow, and the hydraulic diameter of the wire is 0.5-5 mm. 7. The centrifugal flow type vertical structured packing according to claim 1, characterized in that, the helical coil formed by the coiled wire of the packing monomer (2) has a helical diameter of 2-100mm and a pitch of 0.5-4mm . 8. The centrifugal flow type vertical structured packing according to claim 1, characterized in that, the wire rods coiled to form a helical coil are 1-4 strands, and when multiple strands of wire rods are selected for coiling, the wire rods are arranged in parallel to ensure that the spiral diameter And pitch constant. 9. The centrifugal flow type vertical structured packing according to claim 1, characterized in that the wire rod is made of steel, plastic or ceramics.

Images