Rectifying tower and tower plate transformation method thereof

Abstract

The invention discloses a rectifying tower and a tower plate transformation method thereof. The rectifying tower comprises a cylindrical tower body and a plurality of layers of tower plates, the tower body is provided with a feeding hole, a tower bottom liquid outlet, a gas inlet, a tower top outlet and a reflux inlet, and the tower body, the reboiler, the condenser and the separator form a rectifying system. Each layer of tower plate is a circular sieve plate, an opening of one section of the circumference of the tower plate is bent downwards to form an inclined plane tower plate, the projection of an inclined plane on the horizontal plane falls within the outer diameter range of the circular sieve plate, and the included angle between the inclined plane and the horizontal plane is 70-80 degrees; a baffle is arranged at the joint of the sieve plate and the inclined surface, and the openings of the adjacent upper and lower tower plates are symmetrically arranged along the central axis of the tower body. The transformation method comprises the steps of tower stopping treatment, old tower plate dismantling, tower plate machining and installing, checking and the like, and the gas-liquid mass transfer efficiency and the device operation stability can be improved under the condition that a tower shell is not replaced.

Description

Technical Field

[0001] This invention relates to the field of distillation separation technology, and in particular to a distillation column and a method for modifying its trays. Background Technology

[0002] Unsymmetrical dimethylhydrazine (UDMH) is an important organic chemical raw material widely used in aerospace, fertilizers, pesticides, and other fields. Due to the high purity requirements of UDMH, distillation is a widely used process in its production to remove impurities from the raw material. As the core equipment in this separation process, the design of the distillation column's trays directly affects distillation efficiency, energy consumption, and product purity. Traditional distillation column trays mostly adopt a flat plate structure, which typically presents the following problems:

[0003] 1. Low gas-liquid contact efficiency: The surface of traditional flat plate towers is usually relatively flat, and the flow of liquid on the tower plate is prone to forming stagnation zones or uneven flow rates, resulting in insufficient gas-liquid contact area, which in turn affects mass transfer efficiency and separation effect.

[0004] 2. Uneven liquid distribution: When the liquid flows along the surface of the tray after falling from the downcomer, the liquid flow direction is difficult to control because the tray surface is relatively smooth. It tends to concentrate in local areas, resulting in uneven liquid distribution and failure to effectively utilize the mass transfer area of ​​the tray.

[0005] 3. High energy consumption: Due to the limited gas-liquid contact area in traditional tray design, the mass transfer efficiency in the tower is low, requiring a high steam load to maintain the required separation effect, thus resulting in high energy consumption.

[0006] To improve the separation efficiency and reduce energy consumption of distillation columns, the industry has been exploring improved tray structures in recent years. By optimizing the geometry, flow path, and gas-liquid contact of the trays, the mass transfer effect within the column can be significantly improved.

[0007] However, most existing modification solutions are limited to improving gas-liquid flow by optimizing the pore structure of the trays or adding conduit systems, failing to fundamentally improve the flow path and surface contact efficiency of the trays. Existing technologies mostly involve localized optimization of the tray surface structure, and problems such as ineffective utilization of the entire tray surface and uneven gas-liquid contact still exist. Summary of the Invention

[0008] To solve the above-mentioned technical problems, this invention proposes a distillation column and a method for modifying its trays, employing the following technical solution:

[0009] This invention provides a distillation column, including a cylindrical column body and multiple layers of trays disposed within the column body. The column body is provided with a feed inlet, a bottom liquid outlet, a gas inlet, a top outlet, and a reflux inlet. The feed inlet is located in the middle of the column body and is used to continuously feed the raw material liquid to be separated into the feed section of the distillation column, so that the raw material undergoes preliminary mass transfer exchange with the rising gas and falling liquid in the feed section. The column body has a bottom liquid outlet connected to a reboiler. The bottom liquid flows into the reboiler through this outlet and is partially vaporized. The vaporized portion forms vapor rich in light components, which returns to the column through an inlet located at the bottom of the column body. The unvaporized liquid is discharged as heavy components through the heavy component outlet of the reboiler. The top outlet is located at the top of the column body to draw out the top vapor and send it to a condenser for condensation. The condensed liquid enters a separator to separate the reflux liquid from the light component product. Part of the condensate in the separator is returned to the top of the column through a reflux port to form a reflux liquid layer, thereby enhancing the mass transfer capacity at the top of the column and improving the overall separation efficiency within the column.

[0010] The trays are sieve trays, with each layer being a circular sieve tray. An opening is formed on the outer circumference of the circular sieve tray, which then bends downwards to form a downward-sloping tray. The remaining outer circumference of the circular sieve tray, except for the opening, is sealed to the inner wall of the tower, thus creating a sieve tray area in each layer for liquid retention and gas contact. Multiple sieve holes are evenly distributed on the surface of the circular sieve tray to allow upward-flowing gas to pass through and fully contact the liquid on it. After completing gas-liquid contact in the previous tray, the liquid flows to the current circular sieve tray, first forming a liquid layer of a certain height within the sieve tray area, then overflowing into the inclined tray through the circumferential opening, and flowing along the inclined tray under gravity to its lower edge, from which it falls into the next tray. The circumferential openings and inclined trays of adjacent upper and lower trays are symmetrically arranged along the central axis of the tower, causing the liquid flow direction of each tray to alternate, thereby improving the liquid distribution within the tower cross-section.

[0011] Furthermore, the inclined tray extends downward from the opening edge of the circular sieve plate, and its projection on the horizontal plane falls entirely within the circumference of the circular sieve plate, without exceeding the outer diameter of the circular tray, so as to ensure that the overall tray assembly does not interfere with the inner wall of the cylindrical tower body when assembled inside the tower body.

[0012] Furthermore, the angle between the inclined panel and the horizontal plane is 70° to 80°.

[0013] Furthermore, a vertical baffle is installed at the connection between the circular sieve plate and the inclined tray to raise the liquid level in the sieve plate area, stabilize the residence time and flow state of the liquid on the sieve plate, and further improve the gas-liquid mass transfer efficiency.

[0014] On the other hand, the present invention also proposes a method for modifying the above-mentioned distillation column trays, comprising the following steps:

[0015] S1, shut down the distillation column, replace the column with a manhole, and complete the internal cleaning to bring the column into a state where it can be maintained.

[0016] S2, Remove the original tower plate assembly inside the tower body, including removing the original tower plates, downcomers, overflow weirs and their supporting components from the inner wall of the tower body;

[0017] S3, process a circular sieve plate to form an opening on the outer edge of the circular sieve plate, and connect a downwardly extending inclined tower plate to the opening. At the same time, a vertical baffle is set at the connection between the circular sieve plate and the inclined tower plate.

[0018] S4. Install the processed circular sieve plate assembly into the tower body, and seal and fix the outer circumference of the circular sieve plate, except for the open section, to the inner wall of the tower body.

[0019] S5, install adjacent tower plates in a bottom-up order, so that the circumferential openings of adjacent upper and lower tower plates are symmetrically arranged along the central axis of the tower body.

[0020] S6, check the position of each inclined plate to ensure that the projection of the inclined plate on the horizontal plane is within the circumference of the circular sieve plate and does not interfere with the inner wall of the tower.

[0021] S7. Check the fixing points, welds, and angles of the inclined trays of the tray assembly. After confirming that everything is correct, shut down the tower and resume the operation of the distillation tower.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] This invention creates an opening on the outer edge of a circular sieve plate and sets up a downward-bent, high-angle inclined tray, allowing the liquid to flow directly and rapidly down the inclined surface to the next tray after gas-liquid contact is completed. This eliminates the need for traditional downcomers and overflow weirs, simplifies the tray design, reduces flow resistance within the tower, avoids flooding risks, and improves the tray's processing capacity.

[0024] Furthermore, the projection of the inclined tray onto the horizontal plane falls entirely within the circumference of the circular sieve plate, preventing interference with the inner wall of the column. This allows the tray to be directly installed in existing distillation columns without altering the column shell dimensions, significantly improving adaptability and reducing retrofit costs. The openings of adjacent upper and lower trays are symmetrically arranged along the central axis of the column, with the liquid flow direction alternating layer by layer. This improves the uniformity of liquid distribution within the column cross-section, enhances lateral mixing of the fluid within the column, and thus improves gas-liquid contact efficiency and tray efficiency.

[0025] Furthermore, a vertical baffle is installed at the connection between the circular sieve plate and the inclined tray, which can form a more stable liquid layer height in the sieve plate area, allowing the liquid to have a suitable residence time in the sieve plate area, which is conducive to the full conduct of the gas-liquid mass transfer process and improves the separation effect. Through the above structural optimization, the present invention can significantly improve the processing capacity, mass transfer efficiency and operational stability of the distillation column without changing the original column shell. It is suitable for improving the performance of distillation processes and retrofitting old columns, and has significant engineering application value. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of an embodiment of the present invention;

[0027] Figure 2 This is an isometric view of the tray in an embodiment of the present invention;

[0028] Figure 3 This is a top view of the tray in an embodiment of the present invention;

[0029] Figure 4 This is a front view of the tray in an embodiment of the present invention.

[0030] The components are: 1. Tower body; 101. Feed inlet; 102. Bottom liquid outlet; 103. Gas inlet; 104. Top outlet; 105. Reflux outlet; 2. Tower tray; 201. Inclined tray; 202. Sieve hole; 203. Baffle; 3. Reboiler; 4. Condenser; 5. Separator. Detailed Implementation

[0031] The technologies in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0032] like Figure 1As shown, this embodiment provides a distillation column apparatus, including a cylindrical column body 1 and multiple layers of trays 2 disposed inside the column body 1. The column body 1 is provided with a feed inlet 101, a bottom liquid outlet 102, an air inlet 103, a top outlet 104, and a reflux outlet 105. The feed inlet 101 is located in the middle of the column body 1 and is used to introduce the feed liquid to be separated into the column body 1. The bottom liquid outlet 102 is connected to a reboiler 3. The bottom material enters the reboiler 3 through the bottom liquid outlet 102, is heated, partially vaporized, and returns to the bottom of the column body 1 through the air inlet 103. The remaining unvaporized liquid is discharged from the reboiler 3 as heavy components. The top outlet 104 is used to draw out the top vapor and send it to a condenser 4 for condensation. The condensed liquid enters a separator 5. Part of the condensate separated by the separator 5 flows back to the top of the column body 1 through the reflux outlet 105. The remaining light component products are output from the separator 5.

[0033] like Figures 2-4 As shown, each tray 2 is a circular sieve tray structure, consisting of a circular sieve tray body and an inclined tray 201 formed on one side. An opening is formed at the outer circumference of the circular sieve tray, at which a downwardly inclined tray 201 is connected. The remaining circumferential edges of the circular sieve tray, except for the opening section, are sealed to the inner wall of the tower body 1 to form a sieve tray area for liquid retention and gas contact. Multiple sieve holes 202 are uniformly formed on the circular sieve tray to allow gas from bottom to top to pass through the sieve tray and form gas-liquid contact with the liquid on it. Preferably, the sieve holes 202 are uniformly arrayed to improve the gas-liquid contact efficiency of the tray.

[0034] A vertical baffle 203 is installed at the connection between the circular sieve plate and the inclined tray 201 to raise the liquid level in the sieve plate area, allowing the liquid to have a suitable residence time in the circular sieve plate area, thereby ensuring the stability of the mass transfer process in the tray. After the liquid falls from the upper tray to the current circular sieve plate, a certain liquid layer is formed in the sieve plate area, and then overflows along the circumferential opening to the inclined tray 201, and flows down the inclined tray 201 to the end of the inclined surface, thus falling into the next tray 2. To ensure that the liquid flow path does not interfere with the tower structure, in this embodiment, the projection of the inclined tray 201 on the horizontal plane falls entirely within the outer diameter range of the circular sieve plate and does not exceed the inner diameter of the tower body 1.

[0035] In this embodiment, the inclined plate 201 has an inclination angle of 70° to 80° relative to the horizontal plane of the circular sieve plate. This larger inclination angle allows the liquid to quickly leave the sieve plate area, increasing the liquid turnover rate of the plate and reducing liquid accumulation. The length of the inclined plate 201 is designed according to the tower diameter, ensuring reliable liquid flow at its end while maintaining good flow continuity.

[0036] like Figure 1As shown, the circumferential openings of adjacent upper and lower trays 2 are symmetrically arranged along the central axis of the tower body 1, so that the liquid flow direction alternates between the trays, thereby improving the lateral distribution of liquid within the cross-section of the tower body 1, increasing the gas-liquid contact efficiency of the trays and the overall processing capacity of the trays.

[0037] When modifying an old tower, the tray structure of this invention can be used. Specific steps include: shutting down the tower and completing replacement and cleaning; removing the original trays, downcomers, and overflow weirs; and processing as described above. Figures 2-4 The circular sieve plate and inclined tray structure are shown. The circular sieve plate is installed onto the inner wall of the column and sealed and fixed. Adjacent trays are installed symmetrically. The 201 angle of the inclined tray is checked to see if it interferes with the column body. Finally, the overall inspection is completed and the distillation column is restored to operation. The tray structure of this invention eliminates the need for traditional downcomers and overflow weirs, achieving structural simplification and allowing for assembly and modification without changing the column shell size.

[0038] The above embodiments are merely illustrative of the principles of the present invention. Those skilled in the art can make various modifications or equivalent substitutions to the present invention without departing from its spirit and essence, and all such modifications or substitutions should fall within the protection scope of the present invention.

Claims

1. A distillation column, characterized in that, The distillation column includes a cylindrical column body and multiple trays arranged within the column body. The column body is equipped with a feed inlet, a bottom liquid outlet, a gas inlet, a top outlet, and a reflux outlet. The feed inlet is located in the middle of the column body and is used to continuously feed the feed liquid to be separated into the feed section of the distillation column, allowing the feed liquid to undergo preliminary mass transfer exchange with the rising gas and falling liquid within the column. The bottom liquid outlet is connected to a reboiler, through which the bottom liquid flows into the reboiler and is partially vaporized. The vaporized portion forms vapor rich in light components, which returns to the column through the gas inlet located at the bottom of the column body. The unvaporized liquid, as heavy components, is discharged through the heavy component outlet of the reboiler. The top outlet is used to draw out the top vapor and send it to a condenser for condensation. The condensed liquid enters a separator to separate the reflux liquid from the light component products. Part of the condensate in the separator is returned to the top of the column through the reflux outlet to form a reflux liquid layer, thereby enhancing the mass transfer capacity at the top of the column and improving the overall separation efficiency within the column. Each of the tower plates is a circular sieve plate. The outer edge of the circular sieve plate has an opening. The opening is bent downward to form a downward-sloping tower plate. The outer edge of the circular sieve plate, except for the opening section, is sealed to the inner wall of the tower body. Multiple sieve holes are evenly arranged on the surface of the circular sieve plate. The circumferential openings and the sloping tower plates of adjacent upper and lower tower plates are symmetrically arranged along the central axis of the tower body.

2. A distillation column according to claim 1, characterized in that, The inclined tower plate extends downward from the opening edge of the circular sieve plate, and the projection of the inclined tower plate on the horizontal plane falls entirely within the circumference of the circular sieve plate.

3. A distillation column according to claim 2, characterized in that, The angle between the inclined panel and the horizontal plane is 70° to 80°.

4. A distillation column according to any one of claims 1, characterized in that, A vertical baffle is provided at the connection between the circular sieve plate and the inclined tower plate.

5. A method for modifying distillation column trays, characterized in that, The tray modification for a distillation column as described in any one of claims 1 to 4 includes the following steps: S1, shut down the distillation column, replace the column with a manhole, and complete the internal cleaning to bring the column into a state where it can be maintained. S2, Remove the original tower plate assembly inside the tower body, including removing the original tower plates, downcomers, overflow weirs and their supporting components from the inner wall of the tower body; S3, process a circular sieve plate to form an opening on the outer edge of the circular sieve plate, and connect a downwardly extending inclined tower plate to the opening. At the same time, a vertical baffle is set at the connection between the circular sieve plate and the inclined tower plate. S4. Install the processed circular sieve plate assembly into the tower body, and seal and fix the outer circumference of the circular sieve plate, except for the open section, to the inner wall of the tower body. S5, install adjacent tower plates in a bottom-up order, so that the circumferential openings of adjacent upper and lower tower plates are symmetrically arranged along the central axis of the tower body. S6, check the position of each inclined plate to ensure that the projection of the inclined plate on the horizontal plane is within the circumference of the circular sieve plate and does not interfere with the inner wall of the tower. S7. Check the fixing points, welds, and angles of the inclined trays of the tray assembly. After confirming that everything is correct, shut down the tower and resume the operation of the distillation tower.

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