Separation and recovery system for hexamethylenediamine and sodium hydroxide

Abstract

The utility model relates to the technical field of material separation, in particular to a hexamethylenediamine and sodium hydroxide separation and recovery system. The separation and recovery system comprises a decanter, a primary waste alkali separation tank, a secondary waste alkali separation tank, a hexamethylenediamine intermediate tank and a waste alkali tank; an inlet of the decanter is connected with a hexamethylenediamine crude product conveying pipeline, a top outlet is connected with an inlet of the hexamethylenediamine intermediate tank, and a bottom outlet is connected with an inlet of the primary waste alkali separation tank; the upper outlet of the primary waste alkali separation tank is connected with the inlet of the secondary waste alkali separation tank, the middle outlet is respectively connected with the inlet of the secondary waste alkali separation tank and the inlet of the waste alkali tank, and the lower outlet is connected with the inlet of the waste alkali tank; an upper outlet and a middle outlet of the secondary waste alkali separation tank are connected with an inlet of the hexamethylenediamine intermediate tank, and a lower outlet is connected with an inlet of the waste alkali tank. According to the utility model, the content of sodium hydroxide entering the hexamethylenediamine refining system is greatly reduced, the recovery rate of hexamethylenediamine is increased, and the concentration of sodium hydroxide waste liquid is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of material separation, in particular to a separation and recovery system for hexamethylenediamine and sodium hydroxide. Background Art

[0002] In the industrial production of ethylenediamine, sodium hydroxide is generally added as an auxiliary agent, but sodium hydroxide does not participate in the reaction. If it is not discharged from the system for a long time, it will accumulate in the system, affecting the entire production process. In addition, once sodium hydroxide enters the high-temperature section, it will cause extremely serious corrosion to the equipment and cause coking in the distillation tower. Therefore, it is necessary to separate the sodium hydroxide in hexamethylenediamine.

[0003] Patent CN107652188A discloses a sodium hydroxide removal system and a method for removing sodium hydroxide in the production of hexamethylenediamine, which utilizes the specific gravity difference between sodium hydroxide and hexamethylenediamine for precipitation separation and removal. By extending the crude hexamethylenediamine feed pipe and raising the position of the hexamethylenediamine discharge pipe on the original equipment, and adding a sodium hydroxide separation tank, sodium hydroxide is removed from the crude hexamethylenediamine storage tank, reducing the sodium hydroxide content entering the distillation system, ensuring the purification effect of the distillation tower, and extending the operation cycle. However, the removal effect of sodium hydroxide by precipitation separation alone is limited, and it will cause certain corrosion to the equipment in the subsequent high-temperature distillation process.

[0004] Patent CN219983972U discloses a sodium hydroxide separation system in crude hexamethylenediamine. On the basis of patent CN107652188A, an electromagnetic control system is added to reduce manual operation and improve the separation effect to a certain extent. However, it still only relies on precipitation separation to remove sodium hydroxide, and its separation effect is not ideal.

[0005] Therefore, it is necessary to design a separation and recovery system for hexamethylenediamine and sodium hydroxide to improve the removal effect of sodium hydroxide. Utility Model Content

[0006] In view of the deficiencies in the prior art, the purpose of the utility model is to provide a separation and recovery system for hexamethylenediamine and sodium hydroxide, which has a simple structure and is easy to operate, greatly reduces the content of sodium hydroxide entering the hexamethylenediamine refining system, ensures stable production, extends the service life of the equipment, and at the same time increases the recovery rate of hexamethylenediamine and improves the concentration of sodium hydroxide waste liquid, which is conducive to the reuse of sodium hydroxide waste liquid.

[0007] The utility model discloses a separation and recovery system for hexamethylenediamine and sodium hydroxide, comprising a decanter, a primary waste alkali separation tank, a secondary waste alkali separation tank, a hexamethylenediamine intermediate tank and a waste alkali tank; the inlet of the decanter is connected to a hexamethylenediamine crude product conveying pipeline, the top outlet is connected to the inlet of the hexamethylenediamine intermediate tank, and the bottom outlet is connected to the inlet of the primary waste alkali separation tank; the upper outlet of the primary waste alkali separation tank is connected to the inlet of the secondary waste alkali separation tank, the middle outlet is respectively connected to the inlet of the secondary waste alkali separation tank and the inlet of the waste alkali tank, and the lower outlet is connected to the inlet of the waste alkali tank; the upper outlet and the middle outlet of the secondary waste alkali separation tank are connected to the inlet of the hexamethylenediamine intermediate tank, and the lower outlet is connected to the inlet of the waste alkali tank.

[0008] Preferably, the tank bodies of the primary waste alkali separation tank and the secondary waste alkali separation tank are provided with glass windows, through which a visible liquid level is formed, and the separation status in the separation tank can be observed in real time.

[0009] In this device, both the primary waste alkali separation tank and the secondary waste alkali separation tank are provided with three outlets: upper, middle and lower. The waste alkali containing hexamethylenediamine discharged from the decanter first enters the primary waste alkali separation tank. After static separation, the hexamethylenediamine with reduced alkali concentration is discharged to the secondary waste alkali separation tank through the upper outlet. The actual separation situation is observed from the glass window, and it is decided to discharge to the secondary waste alkali separation tank or the waste alkali tank through the middle outlet, and the high-concentration alkali solution is discharged to the waste alkali tank through the lower outlet. The sodium hydroxide concentration in the waste alkali containing hexamethylenediamine after separation in the primary waste alkali separation tank has been greatly reduced. After static separation in the secondary waste alkali separation tank, the hexamethylenediamine with a standard alkali concentration is discharged to the hexamethylenediamine intermediate tank through the upper outlet and the middle outlet, and the high-concentration alkali solution is discharged to the waste alkali tank through the lower outlet.

[0010] Preferably, the first-level waste alkali separation tank is located above the second-level waste alkali separation tank.

[0011] Preferably, the decanter is located above the primary spent alkali separation tank.

[0012] Preferably, the hexamethylenediamine intermediate tank and the waste alkali tank are arranged below the secondary waste alkali separation tank.

[0013] The device adopts a top-down equipment position structure, which can transport and transfer materials through gravity flow, reducing the transportation energy consumption of the pump.

[0014] Preferably, the outlet of the waste alkali tank is connected to a waste alkali recovery pipeline.

[0015] Further preferably, a waste alkali transfer pump is provided on the waste alkali recovery pipeline.

[0016] After separation in the decanter, the primary waste alkali separation tank and the secondary waste alkali separation tank, the high-concentration alkali liquid enters the waste alkali tank and is then sent to the sewage treatment station by the waste alkali transfer pump and used as a pH adjuster. It not only treats the high-concentration alkali liquid containing a small amount of organic matter, but also fully recycles the separated sodium hydroxide.

[0017] Preferably, the outlet of the hexamethylenediamine intermediate tank is connected to the hexamethylenediamine refining pipeline.

[0018] Further preferably, a hexamethylenediamine delivery pump is provided on the hexamethylenediamine refining pipeline.

[0019] After three-stage separation in the decanter, the primary waste alkali separation tank and the secondary waste alkali separation tank, the concentration of sodium hydroxide in the crude hexamethylenediamine is greatly reduced and is sent to the hexamethylenediamine refining system by the hexamethylenediamine delivery pump for further refining.

[0020] Compared with the prior art, the utility model has the following beneficial effects:

[0021] (1) The utility model separates the crude hexamethylenediamine into three stages, namely, a decanter, a primary waste alkali separation tank, and a secondary waste alkali separation tank, thereby greatly reducing the content of sodium hydroxide entering the hexamethylenediamine refining system, ensuring stable production, extending the service life of the equipment, and increasing the recovery rate of hexamethylenediamine and the concentration of the sodium hydroxide waste liquid, which is beneficial to the reuse of the sodium hydroxide waste liquid;

[0022] (2) The primary waste alkali separation tank and the secondary waste alkali separation tank of the utility model both adopt three-layer outlet discharge and are provided with glass windows, so that the destination of the separated liquid can be selected according to the actual separation situation of the materials, thereby improving the separation effect;

[0023] (3) The utility model adopts a top-down equipment position structure, placing the decanter, the primary waste alkali separation tank, and the secondary waste alkali separation tank from top to bottom, and placing the hexamethylenediamine intermediate tank and the waste alkali tank at the bottom. The material can be transported and transferred by gravity flow, reducing the transportation energy consumption of the pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of the structure of the separation and recovery system of hexamethylenediamine and sodium hydroxide of the utility model;

[0025] In the figure: 1. Hexamethylenediamine crude product delivery pipeline; 2. Decanter; 3. Primary waste alkali separation tank; 4. Glass window; 5. Secondary waste alkali separation tank; 6. Hexamethylenediamine intermediate tank; 7. Hexamethylenediamine refining pipeline; 8. Hexamethylenediamine delivery pump; 9. Waste alkali tank; 10. Waste alkali delivery pump; 11. Waste alkali recovery pipeline. DETAILED DESCRIPTION

[0026] The specific implementation modes of the present utility model are further described below in conjunction with the accompanying drawings and embodiments. In order to avoid too many unnecessary details, well-known structures or functions will not be described in detail in the following embodiments.

[0027] Example 1

[0028] like Figure 1 As shown, the separation and recovery system of hexamethylenediamine and sodium hydroxide described in the utility model comprises a decanter 2, a primary waste alkali separation tank 3, a secondary waste alkali separation tank 5, a hexamethylenediamine intermediate tank 6 and a waste alkali tank 9; the inlet of the decanter 2 is connected to the hexamethylenediamine crude product conveying pipeline 1, the top outlet is connected to the inlet of the hexamethylenediamine intermediate tank 6, and the bottom outlet is connected to the inlet of the primary waste alkali separation tank 3; the upper outlet of the primary waste alkali separation tank 3 is connected to the inlet of the secondary waste alkali separation tank 5, the middle outlet is respectively connected to the inlet of the secondary waste alkali separation tank 5 and the inlet of the waste alkali tank 9, and the lower outlet is connected to the inlet of the waste alkali tank 9; the upper outlet and the middle outlet of the secondary waste alkali separation tank 5 are connected to the inlet of the hexamethylenediamine intermediate tank 6, and the lower outlet is connected to the inlet of the waste alkali tank 9.

[0029] The tank bodies of the primary waste alkali separation tank 3 and the secondary waste alkali separation tank 5 are provided with glass windows 4. Through the glass windows 4, a visible liquid level is formed, and the separation situation in the separation tank can be observed in real time.

[0030] The decanter 2 is arranged above the primary waste alkali separation tank 3. The primary waste alkali separation tank 3 is arranged above the secondary waste alkali separation tank 5. The hexamethylenediamine intermediate tank 6 and the waste alkali tank 9 are arranged below the secondary waste alkali separation tank 5. The device adopts a top-down equipment position structure, which can transport and transfer materials through gravity flow, thereby reducing the transportation energy consumption of the pump.

[0031] The outlet of the waste alkali tank 9 is connected to a waste alkali recovery pipeline 11. A waste alkali delivery pump 10 is provided on the waste alkali recovery pipeline 11.

[0032] The outlet of the hexamethylenediamine intermediate tank 6 is connected to a hexamethylenediamine refining pipeline 7. A hexamethylenediamine delivery pump 8 is arranged on the hexamethylenediamine refining pipeline 7.

[0033] The working process of the separation and recovery system of hexamethylenediamine and sodium hydroxide is as follows:

[0034] In the production process of hexamethylenediamine, the crude hexamethylenediamine after the reaction is completed is sent to the decanter 2 through the crude hexamethylenediamine conveying pipeline 1, and sedimentation separation is carried out in the decanter 2 to remove most of the sodium hydroxide in the crude hexamethylenediamine. The waste alkali containing hexamethylenediamine enters the primary waste alkali separation tank 3 from the bottom outlet, and the hexamethylenediamine after the sodium hydroxide is removed enters the hexamethylenediamine intermediate tank 6.

[0035] The primary waste alkali separation tank 3 and the secondary waste alkali separation tank 5 are both provided with three outlets, namely, upper, middle and lower. The waste alkali containing hexamethylenediamine discharged from the decanter 2 first enters the primary waste alkali separation tank 3. After static separation, the hexamethylenediamine with reduced alkali concentration is discharged to the secondary waste alkali separation tank 5 through the upper outlet. The actual separation situation is observed from the glass window 4, and it is decided to discharge to the secondary waste alkali separation tank 5 or the waste alkali tank 9 through the middle outlet, and the high-concentration alkali solution is discharged to the waste alkali tank 9 through the lower outlet; the sodium hydroxide concentration in the waste alkali containing hexamethylenediamine after separation in the primary waste alkali separation tank 3 has been greatly reduced. After static separation in the secondary waste alkali separation tank 5, the hexamethylenediamine with a qualified alkali concentration is discharged to the hexamethylenediamine intermediate tank 6 through the upper outlet and the middle outlet, and the high-concentration alkali solution is discharged to the waste alkali tank 9 through the lower outlet.

[0036] After separation in the decanter 2, the primary waste alkali separation tank 3 and the secondary waste alkali separation tank 5, the high-concentration alkali solution enters the waste alkali tank 9 and is then sent to the sewage treatment station by the waste alkali delivery pump 10 and used as a pH regulator. It not only treats the high-concentration alkali solution containing a small amount of organic matter, but also fully recycles the separated sodium hydroxide.

[0037] After three-stage separation in the decanter 2, the primary waste alkali separation tank 3 and the secondary waste alkali separation tank 5, the sodium hydroxide concentration in the crude hexamethylenediamine is greatly reduced and is sent to the hexamethylenediamine refining system by the hexamethylenediamine delivery pump 8 for further refining.

[0038] The above description is only a preferred embodiment of the utility model and is not intended to limit the utility model. Although the utility model is described in detail with reference to the above embodiments, those skilled in the art can still modify the technical solutions recorded in the above embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. A separation and recovery system for hexamethylenediamine and sodium hydroxide, characterized in that: The invention comprises a decanter (2), a primary waste alkali separation tank (3), a secondary waste alkali separation tank (5), a hexamethylenediamine intermediate tank (6) and a waste alkali tank (9); the inlet of the decanter (2) is connected to a hexamethylenediamine crude product delivery pipeline (1), the top outlet is connected to the inlet of the hexamethylenediamine intermediate tank (6), and the bottom outlet is connected to the inlet of the primary waste alkali separation tank (3); the upper outlet of the primary waste alkali separation tank (3) is connected to the inlet of the secondary waste alkali separation tank (5), the middle outlet is respectively connected to the inlet of the secondary waste alkali separation tank (5) and the inlet of the waste alkali tank (9), and the lower outlet is connected to the inlet of the waste alkali tank (9); the upper outlet and the middle outlet of the secondary waste alkali separation tank (5) are connected to the inlet of the hexamethylenediamine intermediate tank (6), and the lower outlet is connected to the inlet of the waste alkali tank (9).

2. The separation and recovery system of hexamethylenediamine and sodium hydroxide according to claim 1, characterized in that: Glass windows (4) are provided on the tank bodies of the primary waste alkali separation tank (3) and the secondary waste alkali separation tank (5).

3. The separation and recovery system of hexamethylenediamine and sodium hydroxide according to claim 1, characterized in that: The outlet of the waste alkali tank (9) is connected to a waste alkali recovery pipeline (11).

4. The separation and recovery system of hexamethylenediamine and sodium hydroxide according to claim 3, characterized in that: The waste alkali recovery pipeline (11) is provided with a waste alkali delivery pump (10).

5. The separation and recovery system of hexamethylenediamine and sodium hydroxide according to claim 1, characterized in that: The outlet of the hexamethylenediamine intermediate tank (6) is connected to the hexamethylenediamine refining pipeline (7).

6. The separation and recovery system of hexamethylenediamine and sodium hydroxide according to claim 5, characterized in that: The hexamethylenediamine refining pipeline (7) is provided with a hexamethylenediamine delivery pump (8).

7. The separation and recovery system of hexamethylenediamine and sodium hydroxide according to claim 1, characterized in that: The first-level waste alkali separation tank (3) is arranged above the second-level waste alkali separation tank (5).

8. The separation and recovery system of hexamethylenediamine and sodium hydroxide according to claim 7, characterized in that: The decanter (2) is arranged above the primary spent alkali separation tank (3).

9. The separation and recovery system of hexamethylenediamine and sodium hydroxide according to claim 8, characterized in that: The hexamethylenediamine intermediate tank (6) and the waste alkali tank (9) are arranged below the secondary waste alkali separation tank (5).

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