Refining device and refining method of nitrogen-containing compound and application

Abstract

The invention discloses a refining device and method for a nitrogen-containing compound and application. The refining device comprises a light component removal tower, an ammonia recovery tower, a separation tower, a product tower, a wastewater tower, a wastewater cooler and an absorption tank, the tower top of the light component removal tower is connected with the absorption tank; the tower bottom of the light component removal tower is connected with an ammonia recovery tower, and the ammonia recovery tower is connected with a separation tower; the tower top of the separation tower is connected with the product tower, and the tower bottom of the separation tower is connected with the wastewater tower; the tower top of the wastewater tower is connected with a wastewater cooler, and the wastewater cooler is connected with the absorption tank; an inlet is formed in the light component removal tower; outlets for refined products of the nitrogen-containing compound are formed in the product tower and the wastewater tower. The refining device of the nitrogen-containing compound disclosed by the invention can be used for refining a reaction product of acetonitrile prepared by ammoniating methyl acetate, is environment-friendly and is suitable for industrial large-scale continuous operation.

Description

Technical Field

[0001] The present application relates to a refining device and a refining method for nitrogen-containing compounds and their application, and belongs to the technical field of chemical industry. Background Art

[0002] Acetonitrile is a colorless, transparent, sweet-tasting liquid compound. It is an important fine chemical raw material and is widely used in the synthesis of pharmaceutical and pesticide chemical intermediates. It is also an organic solvent with good performance. At present, there are only two mature acetonitrile synthesis routes: the acrylonitrile byproduct method and the acetic acid ammoniation dehydration method. The acetonitrile production of the former is severely restricted by the acrylonitrile production capacity, and the raw materials of the latter are highly corrosive. At the same time, the profit margin is sharply compressed due to the influence of the raw material price. The new acetonitrile preparation routes are basically in the laboratory research stage and have not been explored for industrialization. Therefore, it is necessary to continue research.

[0003] The process of ammoniation and dehydration of methyl acetate is a method for preparing acetonitrile with low cost and high product purity. The industrialization difficulty of this method lies in the separation of raw materials and non-condensable gas phase impurities and the refining process of the acetonitrile product. The present invention provides a method for refining nitrogen-containing compounds obtained by this method. The process is continuous, environmentally friendly, and suitable for large-scale continuous operation in industrialization. Summary of the invention

[0004] According to one aspect of the present application, a refining device for nitrogen-containing compounds is provided, the refining device comprising a lightness removal tower, an ammonia recovery tower, a separation tower, a product tower, a wastewater tower, a wastewater cooler, and an absorption tank;

[0005] The top of the lightness removal tower is connected to an absorption tank;

[0006] The bottom of the light-removal tower is connected to an ammonia recovery tower, and the ammonia recovery tower is connected to a separation tower;

[0007] The top of the separation tower is connected to the product tower, and the bottom of the separation tower is connected to the wastewater tower;

[0008] The top of the wastewater tower is connected to a wastewater cooler, and the wastewater cooler is connected to the absorption tank;

[0009] The lightness removal tower is provided with an inlet;

[0010] The product tower and the wastewater tower are provided with outlets for the refined products of nitrogen-containing compounds.

[0011] Optionally, the reflux ratio of the lightness removal tower is 0.1-20.

[0012] Optionally, the lightness removal tower has 10 to 80 theoretical plates.

[0013] Optionally, the top temperature of the lightness removal tower is -20 to 60°C, and the operating pressure is 200 to 900 kPaA.

[0014] Optionally, the reflux ratio of the ammonia recovery tower is 0.1-10.

[0015] Optionally, the ammonia recovery tower has 10 to 80 theoretical plates.

[0016] Optionally, the top temperature of the ammonia recovery tower is -20 to 60°C, and the operating pressure is 0.5 to 600 kPaA.

[0017] Optionally, the reflux ratio of the separation tower is 0.1-20.

[0018] Optionally, the separation tower has 10 to 80 theoretical plates.

[0019] Optionally, the top temperature of the separation tower is 20-120° C., and the operating pressure is 0.5-600 kPaA.

[0020] Optionally, the reflux ratio of the product tower is 1-50.

[0021] Optionally, the product tower has 20 to 100 theoretical plates.

[0022] Optionally, the top temperature of the product tower is 100-200° C., and the operating pressure is 800-2300 kPaA.

[0023] Optionally, the reflux ratio of the wastewater tower is 0.01-20.

[0024] Optionally, the wastewater tower has 10 to 80 theoretical plates.

[0025] Optionally, the top temperature of the wastewater tower is 10-60° C., and the operating pressure is 0.5-600 kPaA.

[0026] Optionally, the cooling temperature of the wastewater cooler is 15-30°C.

[0027] Optionally, the operating temperature of the absorption tank is 10-40° C., and the operating pressure is 0.5-400 kPaA.

[0028] Optionally, the absorption tank is an insulated container with a gas phase inlet inserted below the liquid surface or a two-phase mixing pipeline with a built-in nozzle or other types of gas-liquid mixer.

[0029] According to another aspect of the present application, a method for refining a nitrogen-containing compound is provided, the method comprising:

[0030] The nitrogen-containing compound is introduced into a reaction device and fractionated to obtain a refined product;

[0031] Wherein, the reaction device is selected from the above-mentioned nitrogen-containing compound purification device.

[0032] Optionally, the nitrogen-containing compound comprises the following components in terms of molar composition:

[0033]

[0034]

[0035] Optionally, the method comprises the following steps:

[0036] (1) nitrogen-containing compounds are introduced into a light-removal tower, and after fractionation, the dimethyl ether at the top of the light-removal tower enters an absorption tank;

[0037] (2) The ammonia at the bottom of the light removal tower enters an ammonia recovery tower, unreacted ammonia is separated at the top of the tower, and the heavy materials at the bottom of the tower enter a separation tower for separation. The light components containing acetonitrile, methanol, and methyl acetate are obtained at the top of the separation tower and enter a product tower for separation. Crude methanol is obtained at the top of the product tower, and acetonitrile is obtained at the bottom of the product tower;

[0038] (3) The heavy components containing water and acetamide at the bottom of the separation tower enter the wastewater tower. The wastewater at the bottom of the separation tower is cooled by a wastewater cooler and then enters the absorption tank. Acetamide is obtained at the bottom of the separation tower.

[0039] Optionally, the method of using the above device comprises the following steps:

[0040] 1) The separated raw materials are first sent to the light removal tower, where the dimethyl ether impurities are separated at the top of the tower and a small amount of ammonia is entrained and sent to the absorption tank;

[0041] 2) Ammonia impurities are mixed with wastewater in the absorption tank and then discharged;

[0042] 3) The material obtained at the bottom of the light removal tower is sent to an ammonia recovery tower, unreacted ammonia is separated at the top of the tower, and the heavy material obtained at the bottom of the tower is sent to a separation tower;

[0043] 4) The separation tower separates the material from the middle, and obtains light components containing acetonitrile, methanol, and methyl acetate at the top of the tower, and heavy components containing water and acetyl at the bottom of the tower;

[0044] 5) The bottom material of the separation tower is separated in a wastewater tower to obtain wastewater and the intermediate product acetamide, and the wastewater is cooled by a wastewater cooler and then sent to an absorption tank;

[0045] 6) The light material at the top of the separation tower is sent to the product tower, where the azeotropic conditions of acetonitrile-methanol are destroyed under high pressure conditions, crude methanol is obtained at the top of the tower, and acetonitrile product is obtained at the bottom of the tower.

[0046] According to another aspect of the present application, there is provided an application of the above-mentioned refining device in the reaction product of ammoniation of methyl acetate to acetonitrile.

[0047] In the present application, a method for refining nitrogen-containing compounds uses a liquid product obtained after flash separation of an aminated product as a raw material (the molar composition of the raw material is 0.005-0.2% methyl acetate, 30.0-80.0% ammonia, 5.0-25.0% acetonitrile, 0.1-1.0% acetamide, 3.0-30.0% methanol, 5.0-25.0% water, and 0.001-1.5% dimethyl ether). The device includes the following parts:

[0048] Light-removal tower, ammonia recovery tower, separation tower, product tower, wastewater tower, wastewater cooler, absorption tank. The refined raw material is first sent to the light-removal tower, and the dimethyl ether impurity is separated at the top of the tower and a small amount of ammonia is entrained, and sent to the absorption tank, where it is mixed with wastewater for absorption and discharged. The material obtained at the bottom of the light-removal tower is sent to the ammonia recovery tower, and the unreacted ammonia is separated at the top of the tower. The heavy material at the bottom of the tower is sent to the separation tower. The separation tower separates the material from the middle, and the light components containing acetonitrile, methanol, and methyl acetate are obtained at the top of the tower, and the heavy components containing water and acetamide are obtained at the bottom of the tower. The material at the bottom of the tower is separated in the wastewater tower to obtain wastewater and the intermediate product acetamide, and the wastewater is sent to the absorption tank after being cooled by the wastewater cooler. The light material at the top of the tower is sent to the product tower, and the azeotropic conditions of acetonitrile-methanol are destroyed under high pressure conditions, and crude methanol is obtained at the top of the tower, and the acetonitrile product is obtained at the bottom of the tower.

[0049] The beneficial effects of this application include:

[0050] In the present application, a liquid product obtained after a rough separation of an ammoniation product is used as a raw material, and after light impurity separation-light raw material recovery-high-pressure azeotropic breaking-wastewater separation and other steps, an acetonitrile product and gaseous and liquid raw materials and intermediate products for recycling are obtained, and trace impurities and non-condensable gases are dissolved at low temperature by self-produced wastewater, thereby avoiding the discharge of polluting gases. The process is continuous, and the refining device can be used for the refining of the reaction product of methyl acetate ammoniation to acetonitrile, which is environmentally friendly and suitable for large-scale continuous operation in industrialization. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 This is a schematic diagram of the structure of the refining device for liquid nitrogen-containing compounds in Example 1 of the present application.

[0052] in:

[0053] 1. Light-removal tower; 2. Ammonia recovery tower; 3. Separation tower; 4. Product tower; 5. Wastewater tower; 6. Wastewater cooler; 7. Absorption tank. DETAILED DESCRIPTION

[0054] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0055] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0056] Example 1

[0057] like Figure 1 The figure shows a refining device for nitrogen-containing compounds, which includes a light-removing tower 1, an ammonia recovery tower 2, a separation tower 3, a product tower 4, a wastewater tower 5, a wastewater cooler 6, and an absorption tank 7; the top of the light-removing tower 1 is connected to the absorption tank 7; the bottom of the light-removing tower 1 is connected to the ammonia recovery tower 2, and the ammonia recovery tower 2 is connected to the separation tower 3; the top of the separation tower 3 is connected to the product tower 4, and the bottom of the separation tower 3 is connected to the wastewater tower 5; the top of the wastewater tower 5 is connected to the wastewater cooler 6, and the wastewater cooler 6 is connected to the absorption tank 7; the absorption tank 7 is an insulated container with a gas phase inlet inserted below the liquid surface or a two-phase mixing pipeline with a built-in nozzle or other type of gas-liquid mixer; the light-removing tower 1 is provided with an inlet; the product tower 4 and the wastewater tower 5 are provided with outlets for the refined products of nitrogen-containing compounds.

[0058] Example 2

[0059] The separation raw material (molar composition is methyl acetate 0.05%, ammonia 54.09%, acetonitrile 14.61%, acetamide 0.91%, methanol 15.34%, water 14.82%, dimethyl ether 0.06%) is first sent to the lightness removal tower 1, the tower top pressure of the lightness removal tower 1 is 700kPaA, the tower top temperature is 7°C, 30 theoretical plates are set, and the reflux ratio is 1.5. The waste gas with a molar content of dimethyl ether of 28.19% is separated at the top of the separation tower 1 and sent to the absorption tank 7, where it is adiabatically mixed with waste water for absorption and then discharged. The material obtained at the bottom of the lightness removal tower 1 is sent to the ammonia recovery tower 2, the tower top pressure of the recovery tower 2 is 300kPaA, the tower top temperature is -9°C, 30 theoretical plates are set, and the reflux ratio is 0.15. The unreacted ammonia with a molar purity of 99.99% is separated at the top of the recovery tower 2, and the heavy material obtained at the bottom of the tower is sent to the separation tower 3. The top pressure of separation tower 3 is 105 kPaA, the top temperature is 71°C, 40 theoretical plates are provided, the reflux ratio is 1, and separation tower 3 separates the material from the middle, and the light components containing acetonitrile, methanol, and methyl acetate are obtained at the top of separation tower 3, and the heavy components containing water and acetamide are obtained at the bottom of separation tower 3. The material at the bottom of separation tower 3 is sent to wastewater tower 5, the top pressure of wastewater tower 5 is 9 kPaA, the top temperature is 44°C, 30 theoretical plates are provided, the reflux ratio is 0.08, and the material is separated in wastewater tower 5 to obtain wastewater and intermediate product acetamide, and the wastewater is cooled to 25°C by wastewater cooler 6 and sent to absorption tank 7. The light material at the top of separation tower 3 is sent to product tower 4. The top pressure of product tower 4 is 1900 kPaA, the top temperature is 164°C, 80 theoretical plates are provided, the reflux ratio is 9, and the azeotropic condition of acetonitrile-methanol is destroyed under high pressure conditions. Crude methanol is obtained at the top of product tower 4, and product acetonitrile is obtained at the bottom of product tower 4.

[0060] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A nitrogen-containing compound purification device, characterized in that: The refining device comprises a light-removal tower (1), an ammonia recovery tower (2), a separation tower (3), a product tower (4), a wastewater tower (5), a wastewater cooler (6), and an absorption tank (7); The top of the light removal tower (1) is connected to an absorption tank (7); The bottom of the light-removal tower (1) is connected to an ammonia recovery tower (2), and the ammonia recovery tower (2) is connected to a separation tower (3); The top of the separation tower (3) is connected to the product tower (4), and the bottom of the separation tower (3) is connected to the wastewater tower (5); The top of the wastewater tower (5) is connected to a wastewater cooler (6), and the wastewater cooler (6) is connected to the absorption tank (7); The light-removal tower (1) is provided with an inlet; The product tower (4) and the wastewater tower (5) are provided with outlets for the refined products of nitrogen-containing compounds.

2. The refining device according to claim 1, characterized in that: The reflux ratio of the light removal tower (1) is 0.1 to 20; Preferably, the number of theoretical plates of the lightness removal tower (1) is 10 to 80; Preferably, the top temperature of the lightness removal tower (1) is -20 to 60°C, and the operating pressure is 200 to 900 kPaA.

3. The refining device according to claim 1, characterized in that: The reflux ratio of the ammonia recovery tower (2) is 0.1 to 10; Preferably, the number of theoretical plates of the ammonia recovery tower (2) is 10 to 80; Preferably, the top temperature of the ammonia recovery tower (2) is -20 to 60°C, and the operating pressure is 0.5 to 600 kPaA.

4. The refining device according to claim 1, characterized in that: The reflux ratio of the separation tower (3) is 0.1 to 20; Preferably, the separation tower (3) has a theoretical plate number of 10 to 80; Preferably, the top temperature of the separation tower (3) is 20-120° C., and the operating pressure is 0.5-600 kPaA.

5. The refining device according to claim 1, characterized in that: The reflux ratio of the product tower (4) is 1 to 50; Preferably, the product column (4) has a theoretical plate number of 20 to 100; Preferably, the top temperature of the product tower (4) is 100-200° C., and the operating pressure is 800-2300 kPaA.

6. The refining device according to claim 1, characterized in that: The reflux ratio of the wastewater tower (5) is 0.01 to 20; Preferably, the number of theoretical plates of the wastewater tower (5) is 10 to 80; Preferably, the top temperature of the wastewater tower (5) is 10-60°C, and the operating pressure is 0.5-600 kPaA. Preferably, the cooling temperature of the wastewater cooler (6) is 15 to 30°C; Preferably, the operating temperature of the absorption tank (7) is 10-40°C, and the operating pressure is 0.5-400 kPaA.

7. A method for purifying a nitrogen-containing compound, characterized in that: The method comprises: The nitrogen-containing compound is introduced into a reaction device and fractionated to obtain a refined product; Wherein, the reaction device is selected from the nitrogen-containing compound purification device according to any one of claims 1 to 6.

8. The purification method according to claim 7, characterized in that: According to the molar composition, the nitrogen-containing compound includes the following components:

9. The refining method according to claim 7, characterized in that: The method comprises the following steps: (1) nitrogen-containing compounds are introduced into a light-removal tower, and after fractionation, the dimethyl ether at the top of the light-removal tower enters an absorption tank; (2) The ammonia at the bottom of the light removal tower enters an ammonia recovery tower, unreacted ammonia is separated at the top of the tower, and the heavy materials at the bottom of the tower enter a separation tower for separation. The light components containing acetonitrile, methanol, and methyl acetate are obtained at the top of the separation tower and enter a product tower for separation. Crude methanol is obtained at the top of the product tower, and acetonitrile is obtained at the bottom of the product tower; (3) The heavy components containing water and acetamide at the bottom of the separation tower enter the wastewater tower. The wastewater at the bottom of the separation tower is cooled by a wastewater cooler and then enters the absorption tank. Acetamide is obtained at the bottom of the separation tower.

10. Use of the refining device according to any one of claims 1 to 6 in the reaction product of ammoniation of methyl acetate to acetonitrile.

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