Crude ethanol purification and recovery system

Abstract

The utility model belongs to the technical field of purification, and relates to a crude ethanol purification and recovery system which comprises a crude ethanol raw material tank, a dehydration unit, an ethanol rectifying tower, an ethanol product tank, a methanol buffer tank and a heavy component removal buffer tank, the crude ethanol raw material tank, the dehydration unit, the ethanol rectifying tower and the ethanol product tank are sequentially communicated along the flow direction of materials; and the methanol buffer tank and the de-heavy buffer tank are respectively communicated with the ethanol rectifying tower. Through the dehydration unit and the ethanol rectifying tower which are arranged in sequence, crude ethanol firstly enters the dehydration unit to be dehydrated; and then methanol and ethanol are obtained through the ethanol rectifying tower, so that azeotropy of ethanol and water in rectification can be effectively avoided, and the recovery rate of ethanol is improved.

Description

Technical Field

[0001] This utility model belongs to the field of purification technology and relates to a crude ethanol purification and recovery system. Background Technology

[0002] In the production of ethylene glycol, crude ethanol is often produced as a byproduct. Crude ethanol can be purified to obtain anhydrous ethanol (hereinafter referred to as ethanol). However, because crude ethanol contains impurities such as methanol and water, direct purification results in a low ethanol content, which does not meet the standards for anhydrous ethanol and cannot be sold directly as a product. Therefore, in actual production, crude ethanol needs to be separated and purified to obtain anhydrous ethanol that meets the first-grade standard of GB / T 6820-2016 Industrial Ethanol.

[0003] Currently, the separation and purification of crude ethanol is achieved by distilling the crude ethanol in a distillation column. While removing methanol and water from the crude ethanol, the product is purified to obtain anhydrous ethanol that meets the requirements. However, the following problems exist: during the distillation of crude ethanol, ethanol and water in the crude ethanol will undergo azeotrope, causing some ethanol and water to be separated from the distillation column along with methanol, affecting the ethanol recovery amount and resulting in a low ethanol recovery rate. Utility Model Content

[0004] In addressing the technical problem in existing crude ethanol separation and purification processes where ethanol and water undergo azeotropic reaction during crude ethanol distillation, resulting in some ethanol and water being separated from the distillation column along with methanol, thus affecting the ethanol recovery rate and leading to a low ethanol recovery rate, this invention provides a crude ethanol purification and recovery system.

[0005] This invention uses a dehydration unit and an ethanol distillation column arranged in sequence. Crude ethanol first enters the dehydration unit for dehydration; then it passes through the ethanol distillation column to obtain methanol and ethanol. This effectively avoids azeotropy between ethanol and water during distillation and improves the ethanol recovery rate.

[0006] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0007] A crude ethanol purification and recovery system includes a crude ethanol feed tank, a dehydration unit, an ethanol distillation column, an ethanol product tank, a methanol buffer tank, and a deweighting buffer tank;

[0008] The crude ethanol feed tank, dehydration unit, ethanol distillation column, and ethanol product tank are connected sequentially along the material flow direction; the methanol buffer tank and the deweighting buffer tank are also connected to the ethanol distillation column.

[0009] Further specifying, the dehydration unit includes a dehydration device, which includes a shell and a dehydration membrane. The dehydration membrane is located on the inner cross section of the shell, dividing the shell into an upper cavity and a lower cavity. The lower cavity is connected to the crude ethanol raw material tank, and the upper cavity is connected to the ethanol distillation column.

[0010] Further specified, the dehydration membrane is an inorganic pervaporation membrane or a reverse osmosis membrane; the pressure difference across the dehydration membrane is 0.32 MPa-0.40 MPa.

[0011] Further, the dehydration device can be one or more. When there are multiple dehydration devices, the multiple dehydration devices are connected in series along the material flow direction. The lower cavity of the first dehydration device is connected to the crude ethanol raw material tank, and the upper cavity of the last dehydration device is connected to the ethanol distillation column.

[0012] Furthermore, an ethanol discharge control valve and a dehydration feed control valve are sequentially installed between the crude ethanol raw material tank and the lower cavity along the material flow direction.

[0013] Furthermore, a dehydration discharge control valve is provided between the dehydration device and the ethanol distillation column.

[0014] Furthermore, a distillation column discharge control valve is provided between the ethanol distillation column and the ethanol product tank.

[0015] Further specified, the ethanol distillation column is externally connected to a distillation column feed line, a distillation column discharge line, a distillation light component line, and a distillation heavy component line; the distillation column feed line is connected to the upper cavity, the distillation column discharge line is connected to the ethanol product tank, and the distillation column discharge control valve is located on the distillation column discharge line; the distillation light component line is connected to the methanol buffer tank, and the distillation heavy component line is connected to the de-heavy buffer tank.

[0016] Further specifying, the crude ethanol purification and recovery system also includes a distillation column discharge circulation pipeline; one end of the distillation column discharge circulation pipeline is connected to the distillation column discharge pipeline, and the other end of the distillation column discharge circulation pipeline is connected to the lower chamber via a dehydration feed control valve.

[0017] Further specifying, a distillation column discharge circulation control valve is installed on the distillation column discharge circulation pipeline, and the distillation column discharge circulation control valve and the dehydration feed control valve are arranged sequentially along the material flow direction.

[0018] Compared with the prior art, the beneficial effects of this utility model are:

[0019] 1. The crude ethanol purification and recovery system provided by this utility model sets up a dehydration unit and an ethanol distillation column. The crude ethanol first enters the dehydration unit for dehydration; then it passes through the ethanol distillation column to obtain methanol and ethanol. This can effectively avoid azeotropy between ethanol and water during distillation and improve the ethanol recovery rate.

[0020] 2. In this utility model, the dehydration unit includes a dehydration device, which comprises a shell and a dehydration membrane. The dehydration membrane is located on the inner cross-section of the shell, dividing the shell into an upper cavity and a lower cavity. The lower cavity is connected to the crude ethanol feed tank, and the upper cavity is connected to the ethanol distillation column. Removing water from the crude ethanol feed through the dehydration membrane not only achieves high dehydration efficiency and a large ethanol recovery rate, but also features a simple structure, easy operation, and energy savings. Furthermore, the dehydration membrane is an inorganic pervaporation membrane or a reverse osmosis membrane; the pressure difference across the dehydration membrane is 0.32 MPa-0.40 MPa. By increasing the permeability of water molecules on the membrane wall, water removal can be maximized, thereby increasing the ethanol recovery rate.

[0021] 3. In this utility model, the crude ethanol purification and recovery system also includes a distillation column discharge circulation pipeline. The distillation column discharge circulation pipeline not only ensures the stable operation of the system and improves the efficiency of ethanol distillation and separation, but also enhances the ethanol recovery amount and recovery efficiency.

[0022] As can be seen, in this invention, the crude ethanol feedstock is first dehydrated to remove water, resulting in a crude ethanol feedstock mainly containing methanol and ethanol. Then, it is further separated by ethanol distillation. Methanol containing a very small amount of ethanol is obtained at the top of the ethanol distillation column, ethanol is collected from the side stream of the ethanol distillation column, and the remaining heavy components are removed from the bottom of the ethanol distillation column. This effectively avoids the phenomenon that some ethanol cannot be recovered due to azeotropy between ethanol and water, and can effectively improve the ethanol recovery rate. Attached Figure Description

[0023] Figure 1 A schematic diagram of the crude ethanol purification and recovery system provided in Example 1;

[0024] Figure 2 This is a schematic diagram of the crude ethanol purification and recovery system provided in Example 2;

[0025] Figure 3 This is a schematic diagram of the dehydration unit structure;

[0026] in:

[0027] 10-Crude ethanol feed tank; 101-Crude ethanol feed line; 102-Crude ethanol discharge line; 103-Crude ethanol discharge control valve; 20-Dehydration unit; 201-Dehydration feed line; 202-Dehydration discharge line; 203-Dehydration feed control valve; 204-Dehydration discharge control valve; 21-First dehydration unit; 22-Second dehydration unit; 23-Third dehydration unit; 30-Ethanol distillation column; 301-Distillation column feed line; 302-Distillation column discharge line; 303-Light component distillation line; 304-Heavy component distillation line; 305-Distillation column discharge control valve; 306-Distillation column discharge circulation line; 307-Distillation column discharge circulation control valve; 40-Ethanol product tank; 50-Methanol buffer tank; 60-De-heavy component buffer tank. Detailed Implementation

[0028] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the scope of protection of the present utility model.

[0029] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0030] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in sequences other than those illustrated or described herein.

[0031] Example 1

[0032] This embodiment provides a crude ethanol purification and recovery system, including a crude ethanol feed tank 10, a dehydration unit 20, an ethanol distillation column 30, an ethanol product tank 40, a methanol buffer tank 50, and a de-weighting buffer tank 60. The crude ethanol feed tank 10, dehydration unit 20, ethanol distillation column 30, and ethanol product tank 40 are sequentially connected along the material flow direction; the methanol buffer tank 50 and the de-weighting buffer tank 60 are also connected to the ethanol distillation column 30. In use, the crude ethanol feed first enters the dehydration unit to remove water; then the water-removed crude ethanol passes through the ethanol distillation column to obtain methanol and ethanol (hereinafter referred to as ethanol). This effectively avoids azeotropy between ethanol and water during distillation, thereby improving the ethanol recovery rate.

[0033] See Figure 1 The crude ethanol feed tank 10 is a cylindrical sealed tank. A crude ethanol feed line 101 is installed on the side wall of the crude ethanol feed tank 10 for conveying crude ethanol feed into the crude ethanol feed tank. A crude ethanol discharge line 102 is connected to the bottom of the crude ethanol feed tank 10 for conveying the crude ethanol feed stored in the crude ethanol feed tank 10 to the dehydration unit 20.

[0034] See Figure 1 The dehydration unit 20 includes a dehydration device, which includes a shell and a dehydration membrane. The dehydration membrane is located on the cross-section inside the shell. The crude ethanol in the crude ethanol feed tank 10 enters the ethanol distillation column 30 after passing through the dehydration membrane.

[0035] In this embodiment, the shell is a hollow cylindrical structure with a dehydration membrane set on the cross-section at the middle position. The dehydration membrane divides the shell into an upper cavity and a lower cavity. The ethanol distillation column 30 is connected to the upper cavity, and the lower cavity is connected to the crude ethanol raw material tank 10. The crude ethanol raw material enters the lower cavity and flows upward in the shell. The water in the crude ethanol raw material is separated from the crude ethanol solvent by the dehydration membrane. The water remains in the lower cavity, and the crude ethanol solvent flows upward through the dehydration membrane into the upper cavity, and is further transported to the ethanol distillation column 30 for distillation to separate ethanol and methanol.

[0036] In this embodiment, the dehydration membrane is used to separate the solvent and water in the crude ethanol feedstock, preventing water from entering the ethanol distillation column 30 and azeotropically reacting with ethanol during distillation, thereby improving the ethanol recovery rate.

[0037] Preferably, the dehydration membrane is an inorganic pervaporation membrane, a reverse osmosis membrane, or other existing dehydration membranes capable of separating crude ethanol and water. The pressure difference across the dehydration membrane is 0.32 MPa to 0.40 MPa. This pressure difference increases the permeability of water molecules on the membrane wall, improving the separation efficiency between water molecules and the solvent (crude ethanol), thereby maximizing water removal and increasing ethanol recovery.

[0038] In this embodiment, there is one dehydration device.

[0039] In this embodiment, the dehydration unit 20 further includes a dehydration feed line 201 and a dehydration discharge line 202; the dehydration feed line 201 and the dehydration discharge line 202 are arranged on the symmetrical side walls of the shell, and are staggered. The crude ethanol discharge line 102 is connected to the interior of the shell via the dehydration feed line 201, and then connected to the ethanol distillation column 30 via the dehydration membrane and the dehydration discharge line 202. Preferably, the crude ethanol raw material tank 10 is connected to the lower cavity via the crude ethanol discharge line 102 and the dehydration feed line 201 in sequence; the upper cavity is connected to the ethanol distillation column 30 via the dehydration discharge line 202.

[0040] In this embodiment, the ethanol distillation column 30 is a cylindrical tank used to distill crude ethanol after removing water, thereby separating methanol and ethanol from the crude ethanol.

[0041] In practice, to facilitate the connection between the ethanol distillation column 30 and other equipment, a distillation column feed line 301, a distillation column discharge line 302, a light component distillation line 303, and a heavy component distillation line 304 are externally connected to the ethanol distillation column 30. The distillation column feed line 301 is connected to the upper cavity, the distillation column discharge line 302 is connected to the ethanol product tank 40, and the distillation column discharge control valve 305 is located on the distillation column discharge line 302. The light component distillation line 303 is connected to the methanol buffer tank 50, and the heavy component distillation line 304 is connected to the de-heavy buffer tank 60.

[0042] Preferably, the feed line 301 and discharge line 302 of the distillation column are located on the middle sidewall of the ethanol distillation column 30, with the feed line 301 above the discharge line 302; the light component distillation line 303 is located at the top of the ethanol distillation column 30, and the heavy component distillation line 304 is located at the bottom of the ethanol distillation column 30. The feed line 301 is used to deliver crude ethanol (after water removal) into the ethanol distillation column 30; the discharge line 302 is used to collect the ethanol separated in the ethanol distillation column 30; the light component distillation line 303 is used to collect the methanol separated in the ethanol distillation column 30; and the heavy component distillation line 304 is used to collect the heavy components (waste liquid) separated in the ethanol distillation column 30.

[0043] In this embodiment, the ethanol product tank 40, the methanol buffer tank 50, and the deweighting buffer tank 60 are all cylindrical sealed tanks; they are used to store ethanol, methanol, and heavy components (waste liquid), respectively.

[0044] In this embodiment, to facilitate the transport of materials within the crude ethanol feedstock tank 10, an ethanol discharge control valve 103 and a dehydration feed control valve 203 are sequentially installed between the crude ethanol feedstock tank 10 and the dehydration device along the material flow direction. Preferably, the ethanol discharge control valve 103 is located on the crude ethanol discharge pipeline 102, and the dehydration feed control valve 203 is located on the dehydration feed pipeline 201. The start and stop of the crude ethanol feedstock transport are controlled by the ethanol discharge control valve 103 and the dehydration feed control valve 203.

[0045] In this embodiment, to facilitate the delivery of the dehydrated crude ethanol to the ethanol distillation column 30, a dehydration discharge control valve 204 is installed between the dehydration device and the ethanol distillation column 30. Preferably, the dehydration discharge control valve 204 is located on the dehydration discharge pipeline 202, and the start and stop of the delivery of the dehydrated crude ethanol are controlled by the dehydration discharge control valve 204.

[0046] In this embodiment, in order to facilitate the delivery of the distilled ethanol to the ethanol product tank 40, a distillation column discharge control valve 305 is provided between the ethanol distillation column 30 and the ethanol product tank 40, and the start and stop of ethanol delivery is controlled by the distillation column discharge control valve 305.

[0047] Example 2

[0048] See Figure 3 Based on Example 1, in the crude ethanol purification and recovery system provided in this example, there are multiple dehydration devices connected in series along the material flow direction. The lower chamber of the first dehydration device is connected to the crude ethanol raw material tank 10, and the upper chamber of the last dehydration device is connected to the ethanol distillation column 30.

[0049] Multiple dehydration devices are connected in series along the material flow direction. Through multi-stage dehydration, the water in the crude ethanol raw material can be removed efficiently, minimizing the risk of water entering the ethanol distillation column 30 and causing azeotropy with ethanol during distillation, thereby further improving the ethanol recovery rate.

[0050] In practice, there are two, three, four, or more dehydration devices.

[0051] Preferably, there are three dehydration devices, specifically including a first dehydration device 21, a second dehydration device 22 and a third dehydration device 23; the first dehydration device 21, the second dehydration device 22 and the third dehydration device 23 are distributed from bottom to top.

[0052] When the three dehydration devices are connected in series along the material flow direction, since the first dehydration device 21, the second dehydration device 22, and the third dehydration device 23 have the same structure, the upper chamber of the first dehydration device 21 is connected to the lower chamber of the second dehydration device 22; the upper chamber of the second dehydration device 22 is connected to the lower chamber of the third dehydration device 23, thus completing the series connection of the three dehydration devices. Finally, the lower chamber of the first dehydration device 21 is connected to the crude ethanol feed tank 10, and the upper chamber of the third dehydration device 23 is connected to the ethanol distillation column 30. Preferably, the crude ethanol feed tank 10 is connected to the lower chamber of the first dehydration device 21 via the crude ethanol discharge pipeline 102 and the dehydration feed pipeline 201, and the upper chamber of the third dehydration device 23 is connected to the ethanol distillation column 30 via the dehydration discharge pipeline 202.

[0053] In practice, the crude ethanol feedstock first enters the lower chamber of the first dehydration device 21, flows upward through the dehydration membrane inside the first dehydration device 21 to achieve the first dehydration; after the first dehydration, the crude ethanol feedstock passes through the dehydration membrane into the upper chamber of the first dehydration device 21; and continues to flow to the lower chamber of the second dehydration device 22, where it undergoes a second dehydration through the dehydration membrane inside the second dehydration device 22. After the second dehydration, the crude ethanol feedstock passes through the dehydration membrane into the upper chamber of the second dehydration device 22; then continues to flow to the lower chamber of the third dehydration device 23, where it undergoes a third dehydration through the dehydration membrane inside the third dehydration device 23; finally, after three dehydrations, the crude ethanol feedstock enters the ethanol distillation column 30 through the dehydration discharge pipeline 202 in the upper chamber of the third dehydration device 23. This embodiment achieves complete removal of water from the crude ethanol feedstock through three dehydration processes, resulting in efficient dehydration and improved ethanol recovery rate.

[0054] Example 3

[0055] See Figure 2 Based on Example 1, the crude ethanol purification and recovery system provided in this example also includes a distillation column discharge circulation pipeline 306; one end of the distillation column discharge circulation pipeline 306 is connected to the distillation column discharge pipeline 302, and the other end of the distillation column discharge circulation pipeline 306 is connected to the lower cavity of the dehydration device via the dehydration feed control valve 203.

[0056] In this embodiment, by setting up the distillation column discharge circulation pipeline 306, on the one hand, when the ethanol product tank 40 overflows or the distillation column discharge pipeline 302 between the ethanol distillation column 30 and the ethanol product tank 40 malfunctions, the corresponding valve is switched, allowing the ethanol collected from the ethanol distillation column 30 to flow into the lower chamber of the dehydration device, ensuring stable system operation; on the other hand, the ethanol collected from the ethanol distillation column 30 is tested. If the purity of the ethanol is unqualified, the unqualified ethanol collected from the ethanol distillation column 30 enters the lower chamber of the dehydration device, and then, after dehydration, re-enters the ethanol distillation column 30 for secondary distillation, thereby improving the purity of the ethanol. In this embodiment, the purity of the ethanol meets the first-class standard of GB / T 6820-2016 Industrial Ethanol.

[0057] Preferably, in this embodiment, for ease of control, a distillation column discharge circulation control valve 307 is provided on the distillation column discharge circulation pipeline 306, and the distillation column discharge circulation control valve 307 and the dehydration feed control valve 203 are arranged sequentially along the material flow direction.

[0058] It should be noted that the crude ethanol purification and recovery system provided by this utility model uses conventional and existing power equipment in the field, preferably a pump, when power is involved in the material conveying process. The setting and operation mode of the power equipment are all existing known technologies and will not be described in detail here. The ethanol distillation column 30 is also existing technology, and its purpose is to achieve the distillation separation of ethanol and methanol, and will not be described in detail here either.

[0059] The crude ethanol purification and recovery system described above solves the problem of low ethanol recovery rate caused by azeotropy between ethanol and water during the distillation process, thereby improving the ethanol recovery rate, increasing the amount of ethanol recovered, and generating economic benefits.

[0060] The above are merely preferred embodiments of this utility model and are not intended to limit the scope of this utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A crude ethanol purification and recovery system, characterized in that, It includes a crude ethanol feed tank (10), a dehydration unit (20), an ethanol distillation column (30), an ethanol product tank (40), a methanol buffer tank (50), and a de-weighting buffer tank (60). The crude ethanol feedstock tank (10), dehydration unit (20), ethanol distillation column (30), and ethanol product tank (40) are connected sequentially along the material flow direction; the methanol buffer tank (50) and de-weighting buffer tank (60) are also connected to the ethanol distillation column (30) respectively. The dehydration unit (20) includes a dehydration device, which includes a shell and a dehydration membrane. The dehydration membrane is located on the inner cross section of the shell, dividing the shell into an upper cavity and a lower cavity. The lower cavity is connected to the crude ethanol raw material tank (10), and the upper cavity is connected to the ethanol distillation column (30).

2. The crude ethanol purification and recovery system according to claim 1, characterized in that, The dehydration membrane is an inorganic pervaporation membrane or a reverse osmosis membrane; the pressure difference across the dehydration membrane is 0.32 MPa - 0.40 MPa.

3. The crude ethanol purification and recovery system according to claim 2, characterized in that, The dehydration device is one or more. When there are multiple dehydration devices, the multiple dehydration devices are connected in series along the material flow direction. The lower cavity of the first dehydration device is connected to the crude ethanol raw material tank (10), and the upper cavity of the last dehydration device is connected to the ethanol distillation column (30).

4. The crude ethanol purification and recovery system according to claim 2, characterized in that, The crude ethanol raw material tank (10) and the lower cavity are sequentially equipped with an ethanol discharge control valve (103) and a dehydration feed control valve (203) along the material flow direction.

5. The crude ethanol purification and recovery system according to claim 4, characterized in that, A dehydration discharge control valve (204) is provided between the dehydration device and the ethanol distillation column (30).

6. The crude ethanol purification and recovery system according to claim 5, characterized in that, A distillation column discharge control valve (305) is provided between the ethanol distillation column (30) and the ethanol product tank (40).

7. The crude ethanol purification and recovery system according to claim 6, characterized in that, The ethanol distillation column (30) is externally connected to a distillation column feed line (301), a distillation column discharge line (302), a distillation light component line (303), and a distillation heavy component line (304); the distillation column feed line (301) is connected to the upper cavity, the distillation column discharge line (302) is connected to the ethanol product tank (40), and the distillation column discharge control valve (305) is located on the distillation column discharge line (302); the distillation light component line (303) is connected to the methanol buffer tank (50), and the distillation heavy component line (304) is connected to the de-heavy buffer tank (60).

8. The crude ethanol purification and recovery system according to claim 7, characterized in that, The crude ethanol purification and recovery system also includes a distillation column discharge circulation pipeline (306); one end of the distillation column discharge circulation pipeline (306) is connected to the distillation column discharge pipeline (302), and the other end of the distillation column discharge circulation pipeline (306) is connected to the lower cavity of the dehydration device via a dehydration feed control valve (203).

9. The crude ethanol purification and recovery system according to claim 8, characterized in that, A distillation column discharge circulation control valve (307) is installed on the distillation column discharge circulation pipeline (306), and the distillation column discharge circulation control valve (307) and the dehydration feed control valve (203) are arranged sequentially along the material flow direction.

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