A plate-packed rectification column

Abstract

The present invention discloses a plate-packed hybrid distillation column. An upper reflux port (5) is provided on the side of the top of the column (4). A number of packing zones I (6) and a number of liquid collection and redistribution devices I (7) are distributed at intervals up and down and are interconnected. A gas-liquid distributor I (8) is provided in each packing zone I (6). A tray assembly (11) is provided in the tray shell (10) of the stripping section (2). The upper part of the feed pipe (9) is connected to the liquid collection and redistribution device I (7) at the lower part of the rectifying section (1), and the lower part of the feed pipe (9) is connected to the inside of the tray shell (10). A number of packing zones II (12) and a number of liquid collection and redistribution devices II (13) are distributed at the lower part of the tray shell (10). A gas-liquid distributor II (17) is provided in each packing zone II (12). A cylinder body (3) is connected to the lower part of the liquid collection and redistribution device II (13) at the lower part of the stripping section (2). The present invention can achieve the effect of stable operation of rectification.

Description

Technical Field

[0001] The present invention relates to a plate-packed hybrid distillation column. Background Art

[0002] Tetrafluoroethylene (English name: Tetrafluoroethylene, abbreviated as TFE), with the molecular formula CF2=CF2, is one of the basic raw materials in the organic fluorine industry and is the monomer for manufacturing polytetrafluoroethylene and other fluoroplastics, fluororubbers, and perfluoropropylene.

[0003] Tetrafluoroethylene is purified by a three-column pressurized distillation method. That is, tetrafluoroethylene coming out of the cracking furnace is pre-treated by removing acid, water, and oxygen, and then enters the three columns for distillation in sequence. Among them, the first column is a rough separation column to remove the cracking raw materials and heavy components, the second column is a light component removal column to remove the light components in tetrafluoroethylene, and the third column is a rectification column to separate the high-boiling impurities in tetrafluoroethylene, and basically tetrafluoroethylene with a purity of more than 99.999% can be obtained.

[0004] In the above background art, trace amounts of water, oxygen, and acid are still introduced during the pre-treatment. Although oxygen is removed from the inhibitor tank at the top of the first column, water and acid generate H+ in the stripping section, and react with the rust (iron(III) oxide) present in the column to form ferric ions. Ferric ions will oxidize tetrafluoroethylene to form epoxy tetrafluoroethylene under acidic conditions. Epoxy tetrafluoroethylene will self-polymerize to produce PTFE and water when encountering H+. Since the concentration of tetrafluoroethylene decreases downward in the stripping section, but the monomer concentration in the stripping section below the feed inlet is still relatively high, self-polymerization will occur to block the packing, affecting the stable operation of the column. Summary of the Invention

[0005] The present invention provides a plate-packed hybrid distillation column, which can achieve the effect of stable operation of distillation.

[0006] The present invention adopts the following technical solutions: A plate-packed rectifying column is successively provided with a rectifying section, a stripping section, and a cylinder from top to bottom. The upper part of the rectifying section is provided with a top of the column. On the side of the top of the column, an upper reflux port is provided. At the lower part of the top of the column, a number of packing zones I and a number of liquid collection and redistribution devices I are distributed. The number of packing zones I and the number of liquid collection and redistribution devices I are distributed at intervals up and down and are interconnected. In each packing zone I, a gas-liquid distributor is provided. The stripping section is successively provided with a feed pipe, a column plate shell, a number of packing zones II, and a number of liquid collection and redistribution devices II from top to bottom. A column plate assembly is provided in the column plate shell. The upper part of the feed pipe is connected to the liquid collection and redistribution device I at the lower part of the rectifying section, and the lower part of the feed pipe is connected to the inside of the column plate shell. At the lower part of the column plate shell, a number of packing zones II and a number of liquid collection and redistribution devices II are distributed. The number of packing zones II and the number of liquid collection and redistribution devices II are distributed at intervals up and down and are interconnected. In each packing zone II, a gas-liquid distributor II is provided. The lower part of the liquid collection and redistribution device II at the lower part of the stripping section is connected to the cylinder. The cylinder is successively provided with a column still material input pipe and a column still material output pipe from top to bottom. The column still material input pipe is installed in the middle of the cylinder, and the column still material output pipe is installed at the bottom of the cylinder. The column still material input pipe and the column still material output pipe are arranged perpendicular to each other.

[0007] At the lower part of the top of the column, ten packing zones I and ten liquid collection and redistribution devices I are distributed. The ten packing zones I and the ten liquid collection and redistribution devices I are distributed at intervals up and down and are interconnected. The packing in the packing zone I is random packing or structured packing. The gas-liquid distributor I is set as a gas-liquid split-type distributor. The liquid collection and redistribution device I is set as a gas-liquid split-type distributor. The column plate assembly successively includes twenty column plates from top to bottom, and the twenty column plates are connected in series. The column plate is a bubble-cap column plate, a floating valve column plate, or a sieve plate. At the lower part of the column plate shell, two packing zones II and two liquid collection and redistribution devices II are distributed. The two packing zones II and the two liquid collection and redistribution devices II are distributed at intervals up and down and are interconnected. The packing in the packing zone II is random packing or structured packing.

[0008] The gas-liquid distributor II is set as a gas-liquid split-type distributor, and the liquid collection and redistribution device II is set as a gas-liquid split-type distributor.

[0009] The present invention has the following beneficial effects: After adopting the above technical solutions, the present invention can prevent the self-polymerization and blockage of tetrafluoroethylene and ensure the stable operation of rectification. Description of the Drawings

[0010] Figure 1 It is a schematic structural diagram of the present invention.

[0011] Figure 2 It is a schematic structural diagram of the column plate assembly of the present invention. Detailed implementation mode

[0012] Example 1. In Figure 1 and Figure 2 of this invention, a plate-packed rectification column is provided. It is successively provided with a rectifying section 1, a stripping section 2 and a cylinder body 3 from top to bottom. The upper part of the rectifying section 1 is provided with a top of the column 4. A top reflux port 5 is provided on the side of the top of the column 4. Several packing zones Ⅰ 6 and several liquid collection and redistribution devices Ⅰ 7 are distributed in the lower part of the top of the column 4. The several packing zones Ⅰ 6 and the several liquid collection and redistribution devices Ⅰ 7 are distributed at intervals up and down and are interconnected. A gas-liquid distributor Ⅰ 8 is provided in each packing zone Ⅰ 6. The stripping section 2 is successively provided with a feed pipe 9, a tray shell 10, several packing zones Ⅱ 12 and several liquid collection and redistribution devices Ⅱ 13 from top to bottom. A tray assembly 11 is provided in the tray shell 10. The upper part of the feed pipe 9 is connected to the liquid collection and redistribution device Ⅰ 7 at the lower part of the rectifying section 1, and the lower part of the feed pipe 9 is connected to the inside of the tray shell 10. Several packing zones Ⅱ 12 and several liquid collection and redistribution devices Ⅱ 13 are distributed in the lower part of the tray shell 10. The several packing zones Ⅱ 12 and the several liquid collection and redistribution devices Ⅱ 13 are distributed at intervals up and down and are interconnected. A gas-liquid distributor Ⅱ 17 is provided in each packing zone Ⅱ 12. The lower part of the liquid collection and redistribution device Ⅱ 13 at the lower part of the stripping section 2 is connected to the cylinder body 3. The cylinder body 3 is successively provided with a tower kettle material input pipe 14 and a tower kettle material output pipe 15 from top to bottom. The kettle material input pipe 14 is installed in the middle of the cylinder body 3, and the tower kettle material output pipe 15 is installed at the bottom of the cylinder body 3. The tower kettle material input pipe 14 and the tower kettle material output pipe 15 are arranged perpendicular to each other. In this example, ten packing zones Ⅰ 6 and ten liquid collection and redistribution devices Ⅰ 7 are distributed in the lower part of the top of the column. The ten packing zones Ⅰ 6 and the ten liquid collection and redistribution devices Ⅰ 7 are distributed at intervals up and down and are interconnected. The packing in the packing zone Ⅰ 6 is random packing or structured packing. The gas-liquid distributor Ⅰ 8 is set as a gas-liquid split-type distributor. The liquid collection and redistribution device Ⅰ 7 is set as a gas-liquid split-type distributor. The tray assembly 11 of this example successively includes twenty trays 16 from top to bottom. The twenty trays 16 are connected in series. The tray 16 is a bubble cap tray, a floating valve tray or a sieve tray. Two packing zones Ⅱ 12 and two liquid collection and redistribution devices Ⅱ 13 are distributed in the lower part of the tray shell 10. The two packing zones Ⅱ 12 and the two liquid collection and redistribution devices Ⅱ 13 are distributed at intervals up and down and are interconnected. The packing in the packing zone Ⅱ 12 is random packing or structured packing. The gas-liquid distributor Ⅱ 17 is set as a gas-liquid split-type distributor. The liquid collection and redistribution device Ⅱ 13 is set as a gas-liquid split-type distributor.

[0013] Usage method of the present invention: For a tetrafluoroethylene device with an annual output of 10 kt, the column diameter of the rectifying column is DN1000, the diameters of the upper reflux port 5 and the feed pipe 9 are DN65, the diameter of the bottom material input pipe 14 is DN200, and the diameter of the bottom material output pipe 15 is DN100. Structured packing is used in the rectifying section and the stripping section. The packing height in the packing zone I 6 and the packing height in the packing zone II 12 are both 24 meters. Sieve trays are used for the trays in the stripping section, and the number of sieve trays is 20. The pretreated tetrafluoroethylene pyrolysis gas enters the rectifying column from the feed pipe 9. Tetrafluoroethylene and light components enter the upper reflux port 5 at the top of the column 4 and are withdrawn. The temperature at the top of the column 4 is -6.5 °C, and the pressure at the top of the column 4 is 1.398 MPaG. The pyrolysis raw materials and heavy components enter the bottom of the column for reboiling and withdrawal. The temperature at the bottom of the column is 41 °C, and the pressure at the top of the column 4 is 1.45 MpaG. After operating for half a year, the pressure difference is stable at 0.055 - 0.06 Mpa.

Claims

1. A plate-packed hybrid distillation column, characterized in that it is successively provided with a rectifying section (1), a stripping section (2) and a cylinder body (3) from top to bottom. The upper part of the rectifying section (1) is provided with a top of the column (4). On the side of the top of the column (4), an upper reflux port (5) is provided. In the lower part of the top of the column (4), a number of packing zones I (6) and a number of liquid collection and redistribution devices I (7) are distributed. The packing in the packing zone I (6) is random packing or structured packing. The liquid collection and redistribution device I (7) is set as a gas-liquid split-flow distributor. A number of packing zones I (6) and a number of liquid collection and redistribution devices I (7) are distributed at intervals up and down and are interconnected. In each packing zone I (6), a gas-liquid distributor I (8) is provided. The gas-liquid distributor I (8) is set as a gas-liquid split-flow distributor. The stripping section (2) is successively provided with a feed pipe (9), a tray shell (10), a number of packing zones II (12) and a number of liquid collection and redistribution devices II (13) from top to bottom. In the tray shell (10), a tray assembly (11) is provided. The tray assembly (11) successively includes twenty trays (16) from top to bottom. The twenty trays (16) are connected in series. The tray (16) is a bubble-cap tray, a valve tray or a sieve tray. The upper part of the feed pipe (9) is connected to the liquid collection and redistribution device I (7) at the lower part of the rectifying section (1), and the lower part of the feed pipe (9) is connected to the inside of the tray shell (10). A number of packing zones II (12) and a number of liquid collection and redistribution devices II (13) are distributed at the lower part of the tray shell (10). The liquid collection and redistribution device II (13) is set as a gas-liquid split-flow distributor. A number of packing zones II (12) and a number of liquid collection and redistribution devices II (13) are distributed at intervals up and down and are interconnected. In each packing zone II (12), a gas-liquid distributor II (17) is provided. The gas-liquid distributor II (17) is set as a gas-liquid split-flow distributor. The packing in the packing zone II (12) is random packing or structured packing. The lower part of the liquid collection and redistribution device II (13) at the lower part of the stripping section (2) is connected to the cylinder body (3). The cylinder body (3) is successively provided with a tower kettle material input pipe (14) and a tower kettle material output pipe (15) from top to bottom. The kettle material input pipe (14) is installed in the middle of the cylinder body (3), and the tower kettle material output pipe (15) is installed at the bottom of the cylinder body (3). The tower kettle material input pipe (14) and the tower kettle material output pipe (15) are arranged perpendicular to each other. There are ten packing zones I (6) and ten liquid collection and redistribution devices I (7) distributed at the lower part of the top of the column. The ten packing zones I (6) and the ten liquid collection and redistribution devices I (7) are distributed at intervals up and down and are interconnected. There are two packing zones II (12) and two liquid collection and redistribution devices II (13) distributed at the lower part of the tray shell (10). The two packing zones II (12) and the two liquid collection and redistribution devices II (13) are distributed at intervals up and down and are interconnected.

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