Apparatus for recovering dipropylene glycol from a propylene glycol by-product
Patent Information
- Application Number
- CN202522299415.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-30
- Publication Date
- 2026-09-18
- Estimated Expiration
- 2035-10-30
AI Technical Summary
[0010] The beneficial effects of this invention are as follows: This invention relies on the propylene glycol distillation column of a dimethyl carbonate production unit. The distillation column carries water, methanol, propylene glycol, dipropylene glycol, and other heavy component impurities generated in the upstream reaction process. Light component impurities such as water and methanol are collected at the top of the column, while propylene glycol product is partially separated in the middle of the column. A mixture of propylene glycol and dipropylene glycol, along with other heavy components, is obtained at the bottom of the column. Then, the mixed alcohol is sent to a mixed alcohol separation column for further intermittent separation to obtain relatively pure propylene glycol and dipropylene glycol products. In summary, this invention, on the one hand, recovers dipropylene glycol from the byproducts of the propylene glycol production unit, reducing production costs compared to the synthetic method for preparing dipropylene glycol; on the other hand, it also increases the production capacity of dipropylene glycol, thereby increasing economic benefits.
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Figure CN224762463U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of propylene glycol production technology, and in particular to an apparatus for recovering dipropylene glycol from propylene glycol byproducts. Background Technology
[0002] Propylene glycol plays an irreplaceable role in many fields. Its production primarily involves the hydration reaction of propylene oxide. In this process, in addition to the main product, propylene glycol, trace amounts of byproducts, such as dipropylene glycol, are also generated. As an important chemical raw material, dipropylene glycol is mainly used in the production of industrial solvents, such as plasticizers, polyester resins, and polyurethane polyol resins. It is also used as an antifreeze and thickener in the cleaning industry, as a stabilizer and defoamer in the coatings industry, and is an ideal solvent for many fragrances and cosmetics, possessing high economic value. Furthermore, with the increasing application of dipropylene glycol in the cosmetics industry in recent years, there is currently a significant market shortage. Therefore, fully recovering and utilizing dipropylene glycol, a byproduct of propylene glycol production, is an important way to improve economic efficiency. Utility Model Content
[0003] The purpose of this invention is to address the aforementioned deficiencies in the existing technology by providing a device for recovering dipropylene glycol from propylene glycol byproducts. This invention, on the one hand, recovers dipropylene glycol from the byproducts of propylene glycol production equipment, reducing production costs compared to the synthetic method for preparing dipropylene glycol; on the other hand, it also increases the production capacity of dipropylene glycol, thereby increasing economic benefits.
[0004] The present invention discloses an apparatus for recovering dipropylene glycol from propylene glycol byproducts. The technical solution includes: a propylene glycol distillation column (1), a mixed alcohol collection pump (3), a mixed alcohol storage tank (4), a mixed alcohol separation column feed pump (5), a mixed alcohol separation column (6), a column top cooler (9), a separation column reflux tank (10), a separation column reflux pump (11), a propylene glycol product tank (12), and a dipropylene glycol product tank (13). The lower outlet of the propylene glycol distillation column (1) is connected to the mixed alcohol storage tank (4) via a pipeline and the mixed alcohol collection pump (3). The outlet of the mixed alcohol storage tank (4) is connected to the side inlet of the mixed alcohol separation tower (6) via a pipeline and the mixed alcohol separation tower feed pump (5). The top of the mixed alcohol separation tower (6) is connected to the tower top cooler (9) via a pipeline. The outlet of the tower top cooler (9) is connected to the separation tower reflux tank (10) via a pipeline. The bottom outlet of the separation tower reflux tank (10) is connected to the propylene glycol product tank (12) and the dipropylene glycol product tank (13) via a feed pipeline. The feed pipeline is connected to the upper side of the mixed alcohol separation tower (6) via a reflux pipeline and the separation tower reflux pump (11).
[0005] Preferably, a reboiler (7) is installed on the lower side of the mixed alcohol separation tower (6), and a pipeline and a heavy component discharge pump (8) are connected to the bottom outlet of the mixed alcohol separation tower (6).
[0006] Preferably, the upper side of the above-mentioned separation tower reflux tank (10) is connected to a vacuum pump (14) via a vacuum line.
[0007] Preferably, a distillation column reboiler (2) is installed on the lower side of the propylene glycol distillation column (1).
[0008] Preferably, the conveying pipelines connected to the upper part of the propylene glycol product tank (12) and the dipropylene glycol product tank (13) are respectively equipped with a first control valve (k1) and a second control valve (k2); a third control valve (k3) is installed on the pipeline at the inlet of the separation tower reflux pump (11).
[0009] Preferably, a fourth control valve (k4) is installed on the vacuum line between the separation tower reflux tank (10) and the vacuum pump (14).
[0010] The beneficial effects of this invention are as follows: This invention relies on the propylene glycol distillation column of a dimethyl carbonate production unit. The distillation column carries water, methanol, propylene glycol, dipropylene glycol, and other heavy component impurities generated in the upstream reaction process. Light component impurities such as water and methanol are collected at the top of the column, while propylene glycol product is partially separated in the middle of the column. A mixture of propylene glycol and dipropylene glycol, along with other heavy components, is obtained at the bottom of the column. Then, the mixed alcohol is sent to a mixed alcohol separation column for further intermittent separation to obtain relatively pure propylene glycol and dipropylene glycol products. In summary, this invention, on the one hand, recovers dipropylene glycol from the byproducts of the propylene glycol production unit, reducing production costs compared to the synthetic method for preparing dipropylene glycol; on the other hand, it also increases the production capacity of dipropylene glycol, thereby increasing economic benefits. Attached Figure Description
[0011] Figure 1 This is a structural schematic diagram of Embodiment 1 of this utility model; Figure 2 This is a structural schematic diagram of Embodiment 2 of this utility model; In the diagram above: 1. Propylene glycol distillation column; 2. Distillation column reboiler; 3. Mixed alcohol discharge pump; 4. Mixed alcohol temporary storage tank; 5. Mixed alcohol separation column feed pump; 6. Mixed alcohol separation column; 7. Separation column reboiler; 8. Heavy component discharge pump; 9. Column top cooler; 10. Separation column reflux tank; 11. Separation column reflux pump; 12. Propylene glycol product tank; 13. Dipropylene glycol product tank; 14. Vacuum pump; 15. First control valve k1; 16. Second control valve k2; 17. Third control valve k3; 18. Fourth control valve k4. Detailed Implementation
[0012] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.
[0013] Example 1, referring to Figure 1 This utility model discloses an apparatus for recovering dipropylene glycol from propylene glycol byproducts, comprising a propylene glycol distillation column 1, a mixed alcohol outflow pump 3, a mixed alcohol storage tank 4, a mixed alcohol separation column feed pump 5, a mixed alcohol separation column 6, a column top cooler 9, a separation column reflux tank 10, a separation column reflux pump 11, a propylene glycol product tank 12, and a dipropylene glycol product tank 13. The lower outlet of the propylene glycol distillation column 1 is connected to the mixed alcohol storage tank 4 via a pipeline and the mixed alcohol outflow pump 3. The outlet of tank 4 is connected to the side inlet of mixed alcohol separation tower 6 via a pipeline and the feed pump 5 of the mixed alcohol separation tower. The top of mixed alcohol separation tower 6 is connected to the top cooler 9 via a pipeline. The outlet of the top cooler 9 is connected to the separation tower reflux tank 10 via a pipeline. The bottom outlet of the separation tower reflux tank 10 is connected to the propylene glycol product tank 12 and the dipropylene glycol product tank 13 via a feed pipeline. The feed pipeline is connected to the upper side of mixed alcohol separation tower 6 via a reflux pipeline and the separation tower reflux pump 11.
[0014] The mixed alcohol separation tower 6 is equipped with a reboiler 7 at its lower side, and a pipeline and a heavy component discharge pump 8 are connected to the bottom outlet of the mixed alcohol separation tower 6.
[0015] The upper side of the aforementioned separation tower reflux tank 10 is connected to a vacuum pump 14 via a vacuum pipeline.
[0016] A distillation column reboiler 2 is installed on the lower side of the aforementioned propylene glycol distillation column 1.
[0017] The conveying pipelines connected to the upper parts of the propylene glycol product tank 12 and the dipropylene glycol product tank 13 are respectively equipped with a first control valve k1 and a second control valve k2; a third control valve k3 is installed on the pipeline at the inlet of the separation tower reflux pump 11.
[0018] In use, the mixed alcohol produced in the propylene glycol distillation column bottom 1 is continuously discharged to the mixed alcohol storage tank 4 at a controlled low flow rate. The discharge flow rate is controlled by the mixed alcohol collection pump 3, and the temperature of the propylene glycol distillation column bottom 1 is controlled by the distillation column reboiler 2 to prevent more side reactions from occurring at high temperatures. The mixed alcohol is continuously fed to the mixed alcohol separation column 6 by the mixed alcohol separation column feed pump 5. The pressure of the mixed alcohol separation column 6 is controlled to not exceed -90 kPa. The bottom of the column is heated by the separation column reboiler 7 to distill the mixed alcohol from the top of the column. After condensation at the top of the column, the light component of propylene glycol product is obtained first. The propylene glycol product is cooled by the column top cooler 9 and then enters the separation column. The reflux tank 10 then opens the first control valve k1, allowing propylene glycol to enter the propylene glycol product tank 12. The production of propylene glycol is then paused when the temperature at the top of the mixed alcohol separation tower 6 reaches 125°C. Once the temperature stabilizes at 130°C, dipropylene glycol is continuously produced. After cooling by the tower top cooler 9, the dipropylene glycol enters the reflux tank 10. The second control valve k2 then opens the dipropylene glycol product tank 13. Additionally, if necessary, the third control valve k3 is opened, and the first and second control valves k1 and k2 are closed, returning the initial product from the reflux tank 10 to the mixed alcohol separation tower 6 for further separation. This invention recovers dipropylene glycol from the byproducts of propylene glycol production, reducing production costs compared to synthetic methods. It also increases dipropylene glycol production capacity, thereby improving economic benefits.
[0019] Example 2: An apparatus for recovering dipropylene glycol from propylene glycol byproducts mentioned in this utility model includes a propylene glycol distillation column 1, a mixed alcohol collection pump 3, a mixed alcohol storage tank 4, a mixed alcohol separation column feed pump 5, a mixed alcohol separation column 6, a column top cooler 9, a separation column reflux tank 10, a separation column reflux pump 11, a propylene glycol product tank 12, and a dipropylene glycol product tank 13. The lower outlet of the propylene glycol distillation column 1 is connected to the mixed alcohol storage tank 4 via a pipeline and the mixed alcohol collection pump 3. The outlet of the temporary storage tank 4 is connected to the side inlet of the mixed alcohol separation tower 6 via a pipeline and the feed pump 5 of the mixed alcohol separation tower. The top of the mixed alcohol separation tower 6 is connected to the top cooler 9 via a pipeline. The outlet of the top cooler 9 is connected to the separation tower reflux tank 10 via a pipeline. The bottom outlet of the separation tower reflux tank 10 is connected to the propylene glycol product tank 12 and the dipropylene glycol product tank 13 via a feed pipeline. The feed pipeline is connected to the upper side of the mixed alcohol separation tower 6 via the reflux pipeline and the separation tower reflux pump 11.
[0020] The difference from Example 1 is: Reference Figure 2 In this embodiment, a fourth control valve k4 is installed on the vacuum pipeline between the separation tower reflux tank 10 and the vacuum pump 14 to facilitate the control of the vacuuming operation of the separation tower reflux tank 10.
[0021] The above description is merely a preferred embodiment of this utility model. Any person skilled in the art may modify this utility model or modify it into an equivalent technical solution using the technical solutions described above. Therefore, any simple modifications or equivalent transformations made based on the technical solutions of this utility model are within the scope of protection claimed by this utility model.
Claims
1. An apparatus for recovering dipropylene glycol from propylene glycol byproducts, characterized in that: The system includes a propylene glycol distillation column (1), a mixed alcohol outflow pump (3), a mixed alcohol storage tank (4), a mixed alcohol separation column feed pump (5), a mixed alcohol separation column (6), a column top cooler (9), a separation column reflux tank (10), a separation column reflux pump (11), a propylene glycol product tank (12), and a dipropylene glycol product tank (13). The lower outlet of the propylene glycol distillation column (1) is connected to the mixed alcohol storage tank (4) via a pipeline and the mixed alcohol outflow pump (3). The outlet of the mixed alcohol storage tank (4) is connected to the mixed alcohol storage tank (4) via a pipeline and the mixed alcohol outflow pump (3). The feed pump (5) of the mixed alcohol separation tower is connected to the side inlet of the mixed alcohol separation tower (6). The top of the mixed alcohol separation tower (6) is connected to the top cooler (9) via a pipeline. The outlet of the top cooler (9) is connected to the reflux tank (10) of the separation tower via a pipeline. The bottom outlet of the reflux tank (10) of the separation tower is connected to the propylene glycol product tank (12) and the dipropylene glycol product tank (13) via a feed pipeline. The feed pipeline is connected to the upper side of the mixed alcohol separation tower (6) via the reflux pipeline and the reflux pump (11) of the separation tower.
2. An apparatus for recovering dipropylene glycol from a propylene glycol by-product according to claim 1, characterized in that: A reboiler (7) is installed on the lower side of the mixed alcohol separation tower (6), and a pipeline and a heavy component discharge pump (8) are connected to the bottom outlet of the mixed alcohol separation tower (6).
3. An apparatus for recovering dipropylene glycol from a propylene glycol by-product according to claim 2, characterized in that: The upper side of the separation tower reflux tank (10) is connected to a vacuum pump (14) via a vacuum line.
4. An apparatus for recovering dipropylene glycol from a propylene glycol by-product according to claim 3, characterized in that: A distillation column reboiler (2) is installed on the lower side of the propylene glycol distillation column (1).
5. The apparatus for recovering dipropylene glycol from propylene glycol byproducts according to claim 4, characterized in that: The feed lines connected to the upper parts of the propylene glycol product tank (12) and the dipropylene glycol product tank (13) are respectively equipped with a first control valve (k1) and a second control valve (k2); a third control valve (k3) is installed on the pipeline at the inlet of the separation tower reflux pump (11).
6. An apparatus for recovering dipropylene glycol from a propylene glycol by-product according to claim 4, characterized by: A fourth control valve (k4) is installed on the vacuum line between the separation tower reflux tank (10) and the vacuum pump (14).