Ethylenediamine rectification device and rectification method

Abstract

The invention discloses an ethidene diamine rectification device and a rectification method, the ethidene diamine rectification device comprises four groups of rectification systems and a tower kettle storage tank which are sequentially connected through pipelines, each group of rectification system comprises a vertically arranged packed tower, and by setting the process parameters of each packed tower, the ethidene diamine can be rectified through the tower kettle storage tank. Dehydration, solvent recovery, N-MeEDA removal and product recovery are sequentially carried out on the ethanediamine mother liquor, after the rectification process steps, an ethanediamine solution with the purity larger than or equal to 99.5% is directly obtained, other technological processes do not need to be carried out, in the rectification process, a solvent recovery tower can extract a solvent for recycling, the solvent serves as a by-product for purification treatment, and the recovery rate of the solvent is greatly increased. Therefore, when the high-quality ethidene diamine is prepared, the reaction efficiency is high, raw materials are saved, the energy consumption is low, and the ethidene diamine is easy to store.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical separation, relates to an ethylenediamine distillation device, and also relates to an ethylenediamine distillation method. Background Art

[0002] In chemical production, ethylenediamine, as an important organic raw material, is widely used in high-end fields such as pharmaceuticals, aerospace, and electronics. These fields have extremely high requirements for the purity of ethylenediamine, which must meet the premium quality standard, that is, a purity of ≥99.5%.

[0003] Currently, the most common ethylenediamine distillation process relies on distillation towers for separation and purification. However, the traditional plate-type distillation towers have a relatively simple internal structure, and the gas-liquid contact area on the tower plates is limited, resulting in low gas-liquid mass transfer efficiency. For example, during the separation of ethylenediamine and impurities with similar boiling points, the gas-liquid cannot fully contact and transfer mass, making it difficult to completely remove the impurities. This makes it difficult to maintain a stable product purity above 99.5%.

[0004] In addition, the conventional distillation process is to remove N-MeEDA first and then dehydrate it. The core reason is to utilize the azeotropic effect of water and N-MeEDA, and sufficient water must be present in the reaction solution. After completion, membrane separation or pervaporation and other steps are required to achieve a higher purity. When faced with ethylenediamine raw materials with complex components, the existing distillation process has insufficient ability to specifically separate different impurities. For example, when organic and inorganic impurities are present in the ethylenediamine raw materials at the same time, it is difficult to achieve efficient separation with the current process flow. It often requires multiple steps of tedious operations, and the separation effect is not ideal. It is difficult to meet the strict requirements for the purity of ethylenediamine in the high-end field, which restricts the widespread application of ethylenediamine in the high-end field and industrial upgrading. Summary of the Invention

[0005] The first object of the present invention is to provide an ethylenediamine distillation device, which solves the problem of limited gas-liquid contact area on the tower plate in the prior art.

[0006] The second object of the present invention is to provide a method for distilling ethylenediamine, which solves the problem in the prior art that the distillation process is difficult to remove N-MeEDA, thereby obtaining ethylenediamine of low purity.

[0007] The first technical solution adopted by the present invention is that the ethylenediamine distillation device includes four groups of distillation systems and tower bottom storage tanks connected in sequence by pipelines; each distillation system includes a vertically placed packed tower; the packed tower has a feed inlet on the side wall, a top discharge port and a reflux port on the top, and a bottom discharge port at the bottom; the bottom discharge port is connected to the feed inlet of the packed tower in the next group of distillation systems through a pipeline; the top discharge port is connected to the tower top condenser and the condensate receiving tank in sequence through a pipeline, and the condensate receiving tank discharge port is connected to the reflux port and the intermediate tank through pipelines respectively; and a tower bottom reboiler is installed at the lower part of the packed tower.

[0008] The first technical solution of the present invention is also characterized in that: The packed tower includes a packing layer, which is divided into an upper distillation section and a lower stripping section, and the feed inlet is located between the distillation section and the stripping section.

[0009] The material of the packing layer is metal structured packing.

[0010] The packed towers in the four distillation systems are the dehydration tower, solvent recovery tower, N-MeEDA removal tower and product recovery tower, respectively. The height ratios of the distillation section to the stripping section of the dehydration tower and solvent recovery tower are both 1:1 to 1:1.4; the height ratios of the distillation section to the stripping section of the N-MeEDA removal tower and product recovery tower are 1.8:1 to 2.2:1.

[0011] A kettle circulation pump is installed on the circulation pipeline of the kettle reboiler, and a temperature control valve is installed on the kettle reboiler.

[0012] A tower top reflux pump is installed at the discharge port of the condensate receiving tank, and the outlet of the tower top reflux pump is connected to the reflux port and the intermediate tank respectively.

[0013] A tower kettle extraction pump is installed at the bottom discharge port of the tower.

[0014] The second technical solution adopted by the present invention is an ethylenediamine distillation method, which uses the above-mentioned ethylenediamine distillation device and is specifically implemented according to the following steps: Step 1, setting the process parameters of each packed tower; the packed towers in the four groups of distillation systems are a dehydration tower, a solvent recovery tower, a N-MeEDA removal tower, and a product recovery tower; Step 2: The ethylenediamine mother liquor enters a dehydration tower for dehydration treatment; Step 3: The dehydrated solution enters a solvent recovery tower for slight negative pressure distillation to fractionate the solvent for recovery; Step 4: The EDA mixed solution after solvent recovery is transported to a N-MeEDA removal tower to fractionate N-MeEDA; Step 5: The mixed solution is transported to a product recovery tower for distillation recovery to obtain a final EDA mixed solution.

[0015] The second technical solution of the present invention is also characterized in that: The process parameters include the height ratio of the rectifying section to the stripping section, the tower top pressure, the tower bottom temperature and the reflux ratio; The process parameters of the dehydration tower are: the height ratio of the distillation section to the stripping section is 1:1~1:1.4, the top pressure is 0.5MpaG~0.7MpaG, the bottom temperature is room temperature, the top temperature is 115℃~123℃, and the reflux ratio is 4:1~6:1; The process parameters set for the solvent recovery tower are: the height ratio of the distillation section to the stripping section is 1:1~1:1.4, the tower top pressure is -0.083MpaG~-0.087MpaG, the tower bottom temperature is 33℃~38℃, the tower top temperature is 27℃~31℃, and the reflux ratio is 2.5:2~3.5:2; The process parameters set for the N-MeEDA removal tower are: the height ratio of the distillation section to the stripping section is 1.8:1~2.2:1, the tower top pressure is -0.083MpaG~-0.087MpaG, the tower bottom temperature is 45℃~55℃, the tower top temperature is 33℃~37℃, and the reflux ratio is 8:1~10:1; The process parameters set for the product recovery tower are: the height ratio of the distillation section to the stripping section is 1.8:1~2.2:1, the top pressure is -0.083MpaG~-0.087MpaG, the bottom temperature is 117℃~127℃, the top temperature is 37℃~43℃, and the reflux ratio is 1:2~1:4.

[0016] The beneficial effects of the present invention are: The present invention uses an ethylenediamine rectification device to implement a rectification method. After the rectification process step, an ethylenediamine solution with a purity of 99.5% or more is directly obtained without the need for other process flows. During the rectification process, a solvent recovery tower can also extract more than 95% of the solvent for reuse. White crystals generated in the bottom of the N-MeEDA removal tower are piperazine, which can be purified as a by-product. Therefore, the present invention prepares high-quality ethylenediamine while having high reaction efficiency, saving raw materials, low energy consumption, and easy storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of the ethylenediamine distillation device of the present invention; Figure 2 It is a schematic structural diagram of each distillation system in the ethylenediamine distillation device of the present invention.

[0018] In the figure, 1. Dehydration tower, 2. Solvent recovery tower, 3. N-MeEDA removal tower, 4. Product recovery tower, 5. Bottom reboiler, 6. Temperature control valve, 7. Bottom circulation pump, 8. Bottom extraction pump, 9. Top condenser, 10. Condensate receiving tank, 11. Top reflux pump, 12. Intermediate tank, 13. Packing tower, 14. Top discharge port, 15. Bottom discharge port, 16. Reflux port, 17. Feed port, 18. Bottom storage tank, 19. Distillation section, 20. Stripping section. DETAILED DESCRIPTION

[0019] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0020] The ethylenediamine distillation device of the present invention is as follows: Figure 1As shown, it includes four groups of distillation systems and a tower bottom storage tank 18 connected in sequence through pipelines; like Figure 2 As shown, each distillation system includes a vertically placed packed tower 13; a feed inlet 17 is opened on the side wall of the packed tower 13, a top discharge port 14 and a reflux port 16 are opened on the top of the tower, and a bottom discharge port 15 is opened at the bottom of the tower; the bottom discharge port 15 is connected to the feed inlet 17 of the packed tower 13 of the next distillation system through a pipeline; The top discharge port 14 is connected to the top condenser 9 and the condensate receiving tank 10 in sequence through pipelines, and the discharge port of the condensate receiving tank 10 is connected to the reflux port 16 and the intermediate tank 12 through pipelines respectively; A tower kettle reboiler 5 is installed at the lower part of the packed tower 13 to provide an ascending gas phase.

[0021] The packed tower 13 includes a packing layer, which is divided into an upper rectifying section 19 and a lower stripping section 20 . The feed inlet 17 is located between the rectifying section 19 and the stripping section 20 .

[0022] The material of the packing layer is metal structured packing, and the grade of the metal structured packing is 316L.

[0023] A kettle circulation pump 7 is installed on the circulation pipeline of the kettle reboiler 5, and a temperature control valve 6 is installed on the kettle reboiler 5; the temperature control valve 6 controls the temperature of the kettle reboiler 5, and the kettle circulation pump 7 is used for forced circulation.

[0024] A tower top reflux pump 11 is installed at the discharge port of the condensation receiving tank 10. The outlet of the tower top reflux pump 11 is connected to the reflux port 16 and the intermediate tank 12 respectively. The tower top reflux pump 11 controls the reflux ratio by controlling the reflux amount.

[0025] A tower kettle extraction pump 8 is installed on the tower bottom discharge port 15 to control the discharge speed of the tower bottom discharge port 15.

[0026] The packed towers 13 in the four groups of distillation systems are, in order, a dehydration tower 1, a solvent recovery tower 2, a N-MeEDA removal tower 3, and a product recovery tower 4; The height ratio of the distillation section to the stripping section of the dehydration tower 1 and the solvent recovery tower 2 is 1:1 to 1:1.4; The height ratio of the distillation section to the stripping section of the N-MeEDA removal tower 3 and the product recovery tower 4 is 1.8:1 to 2.2:1.

[0027] The working principle of the ethylenediamine distillation device of the present invention is as follows: During use, the gas phase separated from each packed tower continuously flows out from the top discharge port 14, is condensed by the condenser 9 and enters the condensation receiving tank 10. When the liquid level in the condensation receiving tank 10 reaches the set liquid level, according to the set reflux ratio, part of the condensate returns to the top of the packed tower 13 through the reflux port 16 for reflux, and the other part flows into the intermediate tank 12 for storage.

[0028] The ethylenediamine mother liquor is first distilled in the dehydration tower 1 to distill water, the solvent tetrahydrofuran is recovered in the solvent recovery tower 2, the N-methylethylenediamine is distilled in the N-MeEDA removal tower 3, the product ethylenediamine is distilled in the product recovery tower 4, and then the remaining waste liquid is collected in the tower bottom storage tank 18.

[0029] The ethylenediamine mother liquor includes 5%~10% N-MeEDA, 70%~75% solvent, 5%~10% water, 8%~11% EDA (ethylenediamine) and other substances, and the total content of each component is 100%.

[0030] The present invention also provides an ethylenediamine distillation method, which is implemented using the above-mentioned ethylenediamine distillation device according to the following steps: Step 1, setting the process parameters of each packed tower; the packed towers 13 in the four groups of distillation systems are, in sequence, a dehydration tower 1, a solvent recovery tower 2, a N-MeEDA removal tower 3, and a product recovery tower 4; The process parameters include the height ratio of the rectifying section to the stripping section, the tower top pressure, the tower bottom temperature and the reflux ratio; The process parameters of the dehydration tower 1 are as follows: the height ratio of the distillation section to the stripping section is 1:1 to 1:1.4, the tower top pressure is 0.5 to 0.7 MPaG, the tower bottom temperature is room temperature, the tower top temperature is 115°C to 123°C, and the reflux ratio is 4:1 to 6:1; the tower bottom reboiler 5 uses 1.3 MPa saturated steam to control the tower bottom temperature of the distillation tower; The process parameters set for the solvent recovery tower 2 are: the height ratio of the distillation section to the stripping section is 1:1~1:1.4, the top pressure is -0.083MpaG~-0.087MpaG, the bottom temperature is 33℃~38℃, the top temperature is 27℃~31℃, and the reflux ratio is 2.5:2~3.5:2; the bottom reboiler 5 uses 0.5MPa saturated steam to control the bottom temperature of the distillation tower; The process parameters set for the N-MeEDA removal tower 3 are as follows: the height ratio of the distillation section to the stripping section is 1.8:1 to 2.2:1, the tower top pressure is -0.083 MPaG to -0.087 MPaG, the tower bottom temperature is 45°C to 55°C, the tower top temperature is 33°C to 37°C, and the reflux ratio is 8:1 to 10:1; the tower bottom reboiler 5 uses 0.5 MPa saturated steam to control the tower bottom temperature of the distillation tower; The process parameters set for the product recovery tower 4 are as follows: the height ratio of the distillation section to the stripping section is 1.8:1 to 2.2:1, the tower top pressure is -0.083 MPaG to -0.087 MPaG, the tower bottom temperature is 117°C to 127°C, the tower top temperature is 37°C to 43°C, and the reflux ratio is 1:2 to 1:4; the tower bottom reboiler 5 uses 1.3 MPa saturated steam to control the tower bottom temperature of the distillation tower; Step 2, the ethylenediamine mother liquor enters the dehydration tower 1 for dehydration treatment; The distilled water flows out through the tower top outlet 14, passes through the condenser 9 to reduce the temperature of the distilled water to below 40°C, and enters the connected condensation receiving tank 10. After the liquid level in the condensation receiving tank 10 reaches 50% (which can be monitored by a remote level gauge), part of the water condensate is sent to the top of the dehydration tower 1 for reflux according to the set reflux ratio, and the other part of the water condensate is sent to the water intermediate tank 12 for storage. The water content obtained from the tower top outlet 14 is 95% to 99%. The EDA (ethylenediamine) content in the mixed solution obtained from the tower bottom outlet 15 is not less than 32%.

[0031] Step 3: The dehydrated mixed solution enters the solvent recovery tower 2 for slight negative pressure distillation to fractionate the recoverable solvent and the EDA mixed solution with most of the solvent removed; The top outlet of the solvent recovery tower 2 obtains a solvent recovery product tetrahydrofuran with a content of 90% to 95%. The temperature of the gaseous solvent drops below 20°C and enters the connected condensation receiving tank 10. After the liquid level in the condensation receiving tank 10 reaches 50%, a portion of the solvent condensate is sent to the top of the solvent recovery tower 2 for reflux according to the set reflux ratio, and the other portion of the solvent condensate is sent to the connected intermediate tank 12 for solvent storage; A mixed solution with an EDA content of not less than 73% is obtained at the bottom discharge port of the solvent recovery tower 2.

[0032] Step 4: The EDA mixed solution after solvent recovery is transported to the N-MeEDA removal tower 3 to fractionate N-MeEDA and the N-MeEDA-free EDA mixed solution; The top outlet of the N-MeEDA removal tower 3 obtains N-MeEDA with a content of 6% to 10%, and the temperature of the gaseous N-MeEDA is reduced to below 25° C., and enters the connected condensation receiving tank 10. After the liquid level in the condensation receiving tank 10 reaches 50%, a portion of the N-MeEDA condensate is sent to the top of the N-MeEDA removal tower 3 for reflux according to the set reflux ratio, and the other portion of the N-MeEDA condensate is sent to the connected intermediate tank for storage; A mixed solution having an EDA content of not less than 95% is obtained at the bottom discharge port of the N-MeEDA removal tower 3.

[0033] Step 5: transporting the EDA mixed solution obtained in step 4 to a product recovery tower 4 for distillation recovery to obtain a final EDA mixed solution; The gaseous EDA temperature is reduced to 25°C and enters the connected condensation receiving tank 10. When the liquid level in the condensation receiving tank 10 reaches 50%, a portion of the EDA condensate is sent to the top of the product recovery tower 4 for reflux according to the set reflux ratio, and the other portion of the EDA condensate is sent to the connected intermediate tank 12 for storage; A final mixed solution having an EDA content of not less than 99.5% is obtained in the intermediate tank 12; The reaction waste liquid flows out of the bottom discharge port of the product recovery tower 4 and is collected in the tower bottom storage tank 18.

[0034] The ethylenediamine distillation method of the present invention performs dehydration first and then removes N-MeEDA, thereby avoiding interference of water on the separation of N-MeEDA. After dehydration, the solution mainly contains EDA and N-MeEDA, thus avoiding formation of azeotropes between water and N-MeEDA. There is no need to utilize the azeotropic effect to separate N-MeEDA, and the two can be directly separated by ordinary distillation. After distillation, ethylenediamine with higher purity can be obtained.

[0035] Example 1 In this embodiment, the ethylenediamine distillation device includes four groups of distillation systems and a tower bottom storage tank 18 connected in sequence through pipelines; Each distillation system includes a vertically placed packed tower 13; a feed inlet 17 is opened on the side wall of the packed tower 13, a top discharge port 14 and a reflux port 16 are opened at the top of the tower, and a bottom discharge port 15 is opened at the bottom of the tower; the bottom discharge port 15 is connected to the feed inlet 17 of the packed tower 13 of the next distillation system through a pipeline; The top discharge port 14 is connected to the top condenser 9 and the condensate receiving tank 10 in sequence through a pipeline. The discharge port of the condensate receiving tank 10 is connected to the reflux port 16 and the intermediate tank 12 through pipelines respectively. A remote liquid level meter is installed on the condensate receiving tank 10 for monitoring. A tower kettle reboiler 5 is installed at the lower part of the packed tower 13; The packed tower 13 includes a packing layer, which is divided into an upper rectifying section 19 and a lower stripping section 20. The feed port 17 is located between the rectifying section 19 and the stripping section 20. The material of the packing layer is metal structured packing, and the grade of metal structured packing is 316L; A tower kettle circulation pump 7 is installed on the circulation pipeline of the tower kettle reboiler 5, and a temperature control valve 6 is installed on the tower kettle reboiler 5; the temperature control valve 6 controls the temperature of the tower kettle reboiler 5, and the tower kettle circulation pump 7 is used for forced circulation; A tower top reflux pump 11 is installed at the discharge port of the condensation receiving tank 10, and the outlet of the tower top reflux pump 11 is connected to the reflux port 16 and the intermediate tank 12 respectively; The tower bottom discharge port 15 is provided with a tower kettle extraction pump 8 .

[0036] The ethylenediamine distillation method of this embodiment uses the above-mentioned ethylenediamine distillation device and is specifically implemented according to the following steps: Step 1, setting the process parameters of each packed tower; the packed towers in the four groups of distillation systems are dehydration tower 1, solvent recovery tower 2, N-MeEDA removal tower 3, and product recovery tower 4; The process parameters include the height ratio of the rectifying section to the stripping section, the tower top pressure, the tower bottom temperature and the reflux ratio. The specific parameters of each packed tower are shown in Table 1 below. Table 1

[0037] Step 2, the ethylenediamine mother liquor enters the dehydration tower 1 for dehydration treatment; The EDA (ethylenediamine) content in the mixed solution obtained at the bottom outlet 15 of the tower is 35%; Step 3: The dehydrated mixed solution enters the solvent recovery tower 2 for slight negative pressure distillation to fractionate the recoverable solvent and the EDA mixed solution with most of the solvent removed; The top discharge port of the solvent recovery tower 2 obtains a solvent recovery product tetrahydrofuran with a content of 92.8%; The EDA content of the mixed solution obtained at the bottom outlet of the solvent recovery tower 2 is 75%; Step 4: The EDA mixed solution after solvent recovery is transported to the N-MeEDA removal tower 3 to fractionate N-MeEDA and the N-MeEDA-free EDA mixed solution; The top outlet of the N-MeEDA removal tower 3 obtains N-MeEDA with a content of 7%; The EDA content in the mixed solution obtained at the bottom outlet of the N-MeEDA removal tower 3 is 97%; Step 5: transporting the EDA mixed solution obtained in step 4 to a product recovery tower 4 for distillation recovery to obtain a final EDA mixed solution; The EDA content in the final mixed solution obtained at the top discharge port of the product recovery tower 4 is 99.58%.

[0038] It can be seen that the ethylenediamine distillation method performed using the ethylenediamine distillation device of the present invention can directly obtain an ethylenediamine solution with a purity of not less than 99.5%.

[0039] Example 2 In this embodiment, the ethylenediamine distillation device includes four groups of distillation systems and a tower bottom storage tank 18 connected in sequence through pipelines; Each distillation system includes a vertically placed packed tower 13; a feed inlet 17 is opened on the side wall of the packed tower 13, a top discharge port 14 and a reflux port 16 are opened at the top of the tower, and a bottom discharge port 15 is opened at the bottom of the tower; the bottom discharge port 15 is connected to the feed inlet 17 of the packed tower 13 of the next distillation system through a pipeline; The top discharge port 14 is connected to the top condenser 9 and the condensate receiving tank 10 in sequence through pipelines, and the discharge port of the condensate receiving tank 10 is connected to the reflux port 16 and the intermediate tank 12 through pipelines respectively; A tower kettle reboiler 5 is installed at the lower part of the packed tower 13; The packed tower 13 includes a packing layer, which is divided into an upper rectifying section 19 and a lower stripping section 20. The feed port 17 is located between the rectifying section 19 and the stripping section 20. The material of the packing layer is metal structured packing, and the grade of the metal structured packing is 316L.

[0040] The ethylenediamine distillation method of this embodiment uses the above-mentioned ethylenediamine distillation device and is specifically implemented according to the following steps: Step 1, setting the process parameters of each packed tower; the packed towers in the four groups of distillation systems are dehydration tower 1, solvent recovery tower 2, N-MeEDA removal tower 3, and product recovery tower 4; The process parameters include the height ratio of the rectifying section to the stripping section, the tower top pressure, the tower bottom temperature and the reflux ratio. The specific parameters of each packed tower are shown in Table 2 below. Table 2

[0041] Step 2, the ethylenediamine mother liquor enters the dehydration tower 1 for dehydration treatment; The EDA (ethylenediamine) content in the mixed solution obtained at the bottom outlet 15 of the tower is 34.8%; Step 3: The dehydrated mixed solution enters the solvent recovery tower 2 for slight negative pressure distillation to fractionate the recoverable solvent and the EDA mixed solution with most of the solvent removed; The top discharge port of the solvent recovery tower 2 obtains a solvent recovery product tetrahydrofuran with a content of 92.5%; The EDA content in the mixed solution obtained at the bottom outlet of the solvent recovery tower 2 is 74.8%; Step 4: The EDA mixed solution after solvent recovery is transported to the N-MeEDA removal tower 3 to fractionate N-MeEDA and the N-MeEDA-free EDA mixed solution; The top outlet of the N-MeEDA removal tower 3 obtains N-MeEDA with a content of 7.9%; The EDA content in the mixed solution obtained at the bottom outlet of the N-MeEDA removal tower 3 was 96.7%; Step 5: transporting the EDA mixed solution obtained in step 4 to a product recovery tower 4 for distillation recovery to obtain a final EDA mixed solution; The EDA content in the final mixed solution obtained at the top discharge port of the product recovery tower 4 is 99.55%.

[0042] It can be seen that the ethylenediamine distillation method performed using the ethylenediamine distillation device of the present invention can directly obtain an ethylenediamine solution with a purity of not less than 99.5%.

[0043] Example 3 In this embodiment, the ethylenediamine distillation device includes four groups of distillation systems and a tower bottom storage tank 18 connected in sequence through pipelines; Each distillation system includes a vertically placed packed tower 13; a feed inlet 17 is opened on the side wall of the packed tower 13, a top discharge port 14 and a reflux port 16 are opened at the top of the tower, and a bottom discharge port 15 is opened at the bottom of the tower; the bottom discharge port 15 is connected to the feed inlet 17 of the packed tower 13 of the next distillation system through a pipeline; The top discharge port 14 is connected to the top condenser 9 and the condensate receiving tank 10 in sequence through a pipeline. The discharge port of the condensate receiving tank 10 is connected to the reflux port 16 and the intermediate tank 12 through pipelines respectively. A remote liquid level meter is installed on the condensate receiving tank 10 for monitoring. A tower kettle reboiler 5 is installed at the lower part of the packed tower 13; The packed tower 13 includes a packing layer, which is divided into an upper rectifying section 19 and a lower stripping section 20. The feed port 17 is located between the rectifying section 19 and the stripping section 20. The material of the packing layer is metal structured packing.

[0044] The ethylenediamine distillation method of this embodiment uses the above-mentioned ethylenediamine distillation device and is specifically implemented according to the following steps: Step 1, setting the process parameters of each packed tower; the packed towers in the four groups of distillation systems are dehydration tower 1, solvent recovery tower 2, N-MeEDA removal tower 3, and product recovery tower 4; The process parameters include the height ratio of the rectifying section to the stripping section, the tower top pressure, the tower bottom temperature and the reflux ratio. The specific parameters of each packed tower are shown in Table 3 below. Table 3

[0045] Step 2, the ethylenediamine mother liquor enters the dehydration tower 1 for dehydration treatment; The EDA (ethylenediamine) content in the mixed solution obtained at the bottom outlet 15 of the tower is 35.1%; Step 3: The dehydrated mixed solution enters the solvent recovery tower 2 for slight negative pressure distillation to fractionate the recoverable solvent and the EDA mixed solution with most of the solvent removed; The top discharge port of the solvent recovery tower 2 obtains a solvent recovery product tetrahydrofuran with a content of 92%; The EDA content of the mixed solution obtained at the bottom outlet of the solvent recovery tower 2 is 74.5%; Step 4: The EDA mixed solution after solvent recovery is transported to the N-MeEDA removal tower 3 to fractionate N-MeEDA and the N-MeEDA-free EDA mixed solution; The top outlet of the N-MeEDA removal tower 3 obtains N-MeEDA with a content of 7.9%; The EDA content in the mixed solution obtained at the bottom outlet of the N-MeEDA removal tower 3 was 97.2%; Step 5: transporting the EDA mixed solution obtained in step 4 to a product recovery tower 4 for distillation recovery to obtain a final EDA mixed solution; The EDA content in the final mixed solution obtained at the top discharge port of the product recovery tower 4 is 99.59%.

[0046] It can be seen that the ethylenediamine distillation method performed using the ethylenediamine distillation device of the present invention can directly obtain an ethylenediamine solution with a purity of not less than 99.5%.

[0047] Example 4 In this embodiment, the ethylenediamine distillation device includes four groups of distillation systems and a tower bottom storage tank 18 connected in sequence through pipelines; Each distillation system includes a vertically placed packed tower 13; a feed inlet 17 is opened on the side wall of the packed tower 13, a top discharge port 14 and a reflux port 16 are opened at the top of the tower, and a bottom discharge port 15 is opened at the bottom of the tower; the bottom discharge port 15 is connected to the feed inlet 17 of the packed tower 13 of the next distillation system through a pipeline; The top discharge port 14 is connected to the top condenser 9 and the condensate receiving tank 10 in sequence through a pipeline. The discharge port of the condensate receiving tank 10 is connected to the reflux port 16 and the intermediate tank 12 through pipelines respectively. A remote liquid level meter is installed on the condensate receiving tank 10 for monitoring. A tower kettle reboiler 5 is installed at the lower part of the packed tower 13; The packed tower 13 includes a packing layer, which is divided into an upper rectifying section 19 and a lower stripping section 20. The feed port 17 is located between the rectifying section 19 and the stripping section 20. The material of the packing layer is metal structured packing, and the grade of metal structured packing is 316L; A tower kettle circulation pump 7 is installed on the circulation pipeline of the tower kettle reboiler 5, and a temperature control valve 6 is installed on the tower kettle reboiler 5; the temperature control valve 6 controls the temperature of the tower kettle reboiler 5, and the tower kettle circulation pump 7 is used for forced circulation; A tower top reflux pump 11 is installed at the discharge port of the condensation receiving tank 10, and the outlet of the tower top reflux pump 11 is connected to the reflux port 16 and the intermediate tank 12 respectively; The tower bottom discharge port 15 is provided with a tower kettle extraction pump 8 .

[0048] The ethylenediamine distillation method of this embodiment uses the above-mentioned ethylenediamine distillation device and is specifically implemented according to the following steps: Step 1, setting the process parameters of each packed tower; the packed towers in the four groups of distillation systems are dehydration tower 1, solvent recovery tower 2, N-MeEDA removal tower 3, and product recovery tower 4; The process parameters include the height ratio of the rectifying section to the stripping section, the tower top pressure, the tower bottom temperature and the reflux ratio. The specific parameters of each packed tower are shown in Table 4 below. Table 4

[0049] Step 2, the ethylenediamine mother liquor enters the dehydration tower 1 for dehydration treatment; The EDA (ethylenediamine) content in the mixed solution obtained at the bottom outlet 15 of the tower is 34.6%; Step 3: The dehydrated mixed solution enters the solvent recovery tower 2 for slight negative pressure distillation to fractionate the recoverable solvent and the EDA mixed solution with most of the solvent removed; The top discharge port of the solvent recovery tower 2 obtains a solvent recovery product tetrahydrofuran with a content of 92.1%; The EDA content of the mixed solution obtained at the bottom outlet of the solvent recovery tower 2 was 74.7%; Step 4: The EDA mixed solution after solvent recovery is transported to the N-MeEDA removal tower 3 to fractionate N-MeEDA and the N-MeEDA-free EDA mixed solution; The top outlet of the N-MeEDA removal tower 3 obtains N-MeEDA with a content of 8%; The EDA content in the mixed solution obtained at the bottom outlet of the N-MeEDA removal tower 3 was 96.8%; Step 5: transporting the EDA mixed solution obtained in step 4 to a product recovery tower 4 for distillation recovery to obtain a final EDA mixed solution; The EDA content in the final mixed solution obtained at the top discharge port of the product recovery tower 4 is 99.58%.

[0050] It can be seen that the ethylenediamine distillation method performed using the ethylenediamine distillation device of the present invention can directly obtain an ethylenediamine solution with a purity of not less than 99.5%.

[0051] Example 5 In this embodiment, the ethylenediamine distillation device includes four groups of distillation systems and a tower bottom storage tank 18 connected in sequence through pipelines; Each distillation system includes a vertically placed packed tower 13; a feed inlet 17 is opened on the side wall of the packed tower 13, a top discharge port 14 and a reflux port 16 are opened at the top of the tower, and a bottom discharge port 15 is opened at the bottom of the tower; the bottom discharge port 15 is connected to the feed inlet 17 of the packed tower 13 of the next distillation system through a pipeline; The top discharge port 14 is connected to the top condenser 9 and the condensate receiving tank 10 in sequence through a pipeline. The discharge port of the condensate receiving tank 10 is connected to the reflux port 16 and the intermediate tank 12 through pipelines respectively. A remote liquid level meter is installed on the condensate receiving tank 10 for monitoring. A tower kettle reboiler 5 is installed at the lower part of the packed tower 13; The packed tower 13 includes a packing layer, which is divided into an upper rectifying section 19 and a lower stripping section 20. The feed port 17 is located between the rectifying section 19 and the stripping section 20. The material of the packing layer is metal structured packing, and the grade of metal structured packing is 316L; A tower kettle circulation pump 7 is installed on the circulation pipeline of the tower kettle reboiler 5, and a temperature control valve 6 is installed on the tower kettle reboiler 5; the temperature control valve 6 controls the temperature of the tower kettle reboiler 5, and the tower kettle circulation pump 7 is used for forced circulation; A tower top reflux pump 11 is installed at the discharge port of the condensation receiving tank 10, and the outlet of the tower top reflux pump 11 is connected to the reflux port 16 and the intermediate tank 12 respectively; The tower bottom discharge port 15 is provided with a tower kettle extraction pump 8 .

[0052] The ethylenediamine distillation method of this embodiment uses the above-mentioned ethylenediamine distillation device and is specifically implemented according to the following steps: Step 1, setting the process parameters of each packed tower; the packed towers in the four groups of distillation systems are dehydration tower 1, solvent recovery tower 2, N-MeEDA removal tower 3, and product recovery tower 4; The process parameters include the height ratio of the rectifying section to the stripping section, the tower top pressure, the tower bottom temperature and the reflux ratio. The specific parameters of each packed tower are shown in Table 5 below. Table 5

[0053] Step 2, the ethylenediamine mother liquor enters the dehydration tower 1 for dehydration treatment; The EDA (ethylenediamine) content in the mixed solution obtained at the bottom outlet 15 of the tower is 35.1%; Step 3: The dehydrated mixed solution enters the solvent recovery tower 2 for slight negative pressure distillation to fractionate the recoverable solvent and the EDA mixed solution with most of the solvent removed; The top discharge port of the solvent recovery tower 2 obtains a solvent recovery product tetrahydrofuran with a content of 93%; The EDA content in the mixed solution obtained at the bottom outlet of the solvent recovery tower 2 was 74.9%; Step 4: The EDA mixed solution after solvent recovery is transported to the N-MeEDA removal tower 3 to fractionate N-MeEDA and the N-MeEDA-free EDA mixed solution; The top outlet of the N-MeEDA removal tower 3 obtains N-MeEDA with a content of 8%; The EDA content in the mixed solution obtained at the bottom outlet of the N-MeEDA removal tower 3 was 96.7%; Step 5: transporting the EDA mixed solution obtained in step 4 to a product recovery tower 4 for distillation recovery to obtain a final EDA mixed solution; The EDA content in the final mixed solution obtained at the top discharge port of the product recovery tower 4 is 99.54%.

[0054] It can be seen that the ethylenediamine distillation method performed using the ethylenediamine distillation device of the present invention can directly obtain an ethylenediamine solution with a purity of not less than 99.5%.

[0055] Example 6 In this embodiment, the ethylenediamine distillation device includes four groups of distillation systems and a tower bottom storage tank 18 connected in sequence through pipelines; Each distillation system includes a vertically placed packed tower 13; a feed inlet 17 is opened on the side wall of the packed tower 13, a top discharge port 14 and a reflux port 16 are opened at the top of the tower, and a bottom discharge port 15 is opened at the bottom of the tower; the bottom discharge port 15 is connected to the feed inlet 17 of the packed tower 13 of the next distillation system through a pipeline; The top discharge port 14 is connected to the top condenser 9 and the condensate receiving tank 10 in sequence through a pipeline. The discharge port of the condensate receiving tank 10 is connected to the reflux port 16 and the intermediate tank 12 through pipelines respectively. A remote liquid level meter is installed on the condensate receiving tank 10 for monitoring. A tower kettle reboiler 5 is installed at the lower part of the packed tower 13; The packed tower 13 includes a packing layer, which is divided into an upper rectifying section 19 and a lower stripping section 20. The feed port 17 is located between the rectifying section 19 and the stripping section 20. The material of the packing layer is metal structured packing, and the grade of metal structured packing is 316L; A tower kettle circulation pump 7 is installed on the circulation pipeline of the tower kettle reboiler 5, and a temperature control valve 6 is installed on the tower kettle reboiler 5; the temperature control valve 6 controls the temperature of the tower kettle reboiler 5, and the tower kettle circulation pump 7 is used for forced circulation; A tower top reflux pump 11 is installed at the discharge port of the condensation receiving tank 10, and the outlet of the tower top reflux pump 11 is connected to the reflux port 16 and the intermediate tank 12 respectively; The tower bottom discharge port 15 is provided with a tower kettle extraction pump 8 .

[0056] The ethylenediamine distillation method of this embodiment uses the above-mentioned ethylenediamine distillation device and is specifically implemented according to the following steps: Step 1, setting the process parameters of each packed tower; the packed towers in the four groups of distillation systems are dehydration tower 1, solvent recovery tower 2, N-MeEDA removal tower 3, and product recovery tower 4; The process parameters include the height ratio of the rectifying section to the stripping section, the tower top pressure, the tower bottom temperature and the reflux ratio. The specific parameters of each packed tower are shown in Table 6 below. Table 6

[0057] Step 2, the ethylenediamine mother liquor enters the dehydration tower 1 for dehydration treatment; The EDA (ethylenediamine) content in the mixed solution obtained at the bottom outlet 15 of the tower is 35.2%; Step 3: The dehydrated mixed solution enters the solvent recovery tower 2 for slight negative pressure distillation to fractionate the recoverable solvent and the EDA mixed solution with most of the solvent removed; The top discharge port of the solvent recovery tower 2 obtains a solvent recovery product tetrahydrofuran with a content of 93.1%; The EDA content in the mixed solution obtained at the bottom outlet of the solvent recovery tower 2 was 75.1%; Step 4: The EDA mixed solution after solvent recovery is transported to the N-MeEDA removal tower 3 to fractionate N-MeEDA and the N-MeEDA-free EDA mixed solution; The top outlet of the N-MeEDA removal tower 3 obtains N-MeEDA with a content of 7.9%; The EDA content in the mixed solution obtained at the bottom outlet of the N-MeEDA removal tower 3 was 96.5%; Step 5: transporting the EDA mixed solution obtained in step 4 to a product recovery tower 4 for distillation recovery to obtain a final EDA mixed solution; The EDA content in the final mixed solution obtained at the top discharge port of the product recovery tower 4 is 99.58%.

[0058] It can be seen that the ethylenediamine distillation method performed using the ethylenediamine distillation device of the present invention can directly obtain an ethylenediamine solution with a purity of not less than 99.5%.

Claims

1. Ethylenediamine distillation device, characterized in that, It includes four groups of distillation systems and tower bottom storage tanks (18) connected in sequence through pipelines; Each distillation system includes a vertically placed packed tower (13); a feed inlet (17) is provided on the side wall of the packed tower (13); a top discharge port (14) and a reflux port (16) are provided on the top of the tower; and a bottom discharge port (15) is provided at the bottom of the tower; the bottom discharge port (15) is connected to a feed inlet (17) of a packed tower (13) in the next distillation system through a pipeline; The tower top discharge port (14) is connected to the tower top condenser (9) and the condensate receiving tank (10) in sequence through pipelines, and the discharge port of the condensate receiving tank (10) is connected to the reflux port (16) and the intermediate tank (12) through pipelines. A tower kettle reboiler (5) is installed at the lower part of the packed tower (13).

2. The ethylenediamine distillation device according to claim 1, characterized in that The packed tower (13) includes a packing layer, which is divided into an upper distillation section (19) and a lower stripping section (20). The feed inlet (17) is located between the distillation section (19) and the stripping section (20).

3. The ethylenediamine rectification device according to claim 2, characterized in that: The material of the packing layer is metal structured packing.

4. The ethylenediamine distillation device according to claim 2, characterized in that: The packed towers (13) in the four groups of distillation systems are, in order, a dehydration tower (1), a solvent recovery tower (2), an N-MeEDA removal tower (3), and a product recovery tower (4); The height ratio of the distillation section to the stripping section of the dehydration tower (1) and the solvent recovery tower (2) is 1:1 to 1:1.4; The height ratio of the distillation section to the stripping section of the N-MeEDA removal tower (3) and the product recovery tower (4) is 1.8:1 to 2.2:

1.

5. The ethylenediamine rectification device according to claim 1, characterized in that: A tower kettle circulation pump (7) is installed on the circulation pipeline of the tower kettle reboiler (5), and a temperature control valve (6) is installed on the tower kettle reboiler (5).

6. The ethylenediamine rectification device according to claim 1, characterized in that: A tower top reflux pump (11) is installed at the discharge port of the condensation receiving tank (10), and the outlet of the tower top reflux pump (11) is connected to the reflux port (16) and the intermediate tank (12) respectively.

7. The ethylenediamine distillation device according to claim 1, characterized in that: A tower kettle extraction pump (8) is installed at the tower bottom discharge port (15).

8. Ethylenediamine distillation method, characterized in that, The distillation is carried out using the ethylenediamine distillation apparatus according to any one of claims 1 to 7, specifically by the following steps: Step 1, setting the process parameters of each packed tower; the packed towers (13) in the four groups of distillation systems are a dehydration tower (1), a solvent recovery tower (2), a N-MeEDA removal tower (3) and a product recovery tower (4); Step 2: The ethylenediamine mother liquor enters the dehydration tower (1) for dehydration treatment; Step 3: The dehydrated solution enters the solvent recovery tower (2) for slight negative pressure distillation to fractionate the solvent for recovery; Step 4: The EDA mixed solution after solvent recovery is transported to the N-MeEDA removal tower (3) to fractionate N-MeEDA; Step 5: The mixed solution is transported to a product recovery tower (4) for distillation to obtain a final EDA mixed solution.

9. The ethylenediamine rectification method according to claim 8, characterized in that: The process parameters include the height ratio of the rectifying section to the stripping section, the tower top pressure, the tower bottom temperature and the reflux ratio; The process parameters of the dehydration tower (1) are as follows: the height ratio of the rectifying section to the stripping section is 1:1~1:1.4, the tower top pressure is 0.5MpaG~0.7MpaG, the tower bottom temperature is room temperature, the tower top temperature is 115℃~123℃, and the reflux ratio is 4:1~6:1; The process parameters set for the solvent recovery tower (2) are: the height ratio of the distillation section to the stripping section is 1:1~1:1.4, the tower top pressure is -0.083MpaG~-0.087MpaG, the tower bottom temperature is 33℃~38℃, the tower top temperature is 27℃~31℃, and the reflux ratio is 2.5:2~3.5:2; The process parameters set for the N-MeEDA removal tower (3) are as follows: the height ratio of the rectifying section to the stripping section is 1.8:1~2.2:1, the tower top pressure is -0.083MpaG~-0.087MpaG, the tower bottom temperature is 45℃~55℃, the tower top temperature is 33℃~37℃, and the reflux ratio is 8:1~10:1; The process parameters set for the product recovery tower (4) are as follows: the height ratio of the distillation section to the stripping section is 1.8:1~2.2:1, the tower top pressure is -0.083MpaG~-0.087MpaG, the tower bottom temperature is 117℃~127℃, the tower top temperature is 37℃~43℃, and the reflux ratio is 1:2~1:4.

Images