Separation apparatus and separation method for liquid phase ammonia-containing mixed products and application

Abstract

The application discloses a separation device and method for liquid-phase ammonia-containing mixed products and application, and the separation device comprises a light-removing column, an ammonia recovery column, a separation column, an azeotrope column, a product column, an ester recovery column, an acetonitrile column and a mixing tank. The application takes a liquid-phase product obtained after crude separation of an ammoniated product as raw material, and through steps of light-impurity separation-light-raw-material recovery-sequential rectification-azeotrope separation-high-pressure azeotrope breaking, acetoamide main products, acetonitrile by-products and recycled gas and liquid-phase raw materials are obtained, and trace impurity non-condensable gas is dissolved through self-produced wastewater, so that the pollution gas is avoided to be discharged. The separation method can be used for separation of a pilot body of methyl acetate ammoniation acetonitrile, is environment-friendly and suitable for industrialized large-scale continuous operation.

Description

TECHNICAL FIELD

[0001] The application relates to a separation device and method for liquid-phase ammonia-containing mixed products and application, and belongs to the technical field of chemical industry. BACKGROUND

[0002] Acetonitrile is a colorless transparent liquid compound with a sweet taste, is an important fine chemical raw material, is widely used in the synthesis of pharmaceutical, pesticide and chemical intermediates, and is also a good organic solvent. At present, the mature acetonitrile synthesis route only has two kinds of acetonitrile by-product method and acetic acid ammoniation dehydration method. The acetonitrile yield of the former is seriously restricted by the acrylonitrile production capacity, the raw material of the latter has strong corrosion, and the profit space is sharply compressed due to the influence of the raw material price. New acetonitrile preparation routes are basically in the laboratory research stage and have not been industrialized, so it is necessary to continuously research.

[0003] The acetic acid methyl ester two-step ammoniation dehydration process is a low-cost and high-product-purity acetonitrile preparation method. The industrialization difficulty of the method lies in the separation and purification process of acetic acid methyl ester ammoniation to prepare acetamide in the first step. The application provides a separation method for the ammoniation liquid-phase mixture of the method, which is continuous, environment-friendly and suitable for industrialized large-scale continuous operation. SUMMARY

[0004] According to one aspect of the application, a separation device for liquid-phase ammonia-containing mixed products is provided, which comprises a light-removing column, an ammonia recovery column, a separation column, an azeotropic column, a product column, an ester recovery column, an acetonitrile column and a mixing tank.

[0005] The light-removing column is connected with the ammonia recovery column, and the ammonia recovery column is connected with the separation column.

[0006] The top of the separation column is connected with the azeotropic column, the top of the azeotropic column is connected with the ester recovery column, and the top of the ester recovery column is connected with the azeotropic column.

[0007] The bottom of the azeotropic column is connected with the acetonitrile column.

[0008] The bottom of the separation column is connected with the product column, and the top of the product column is connected with the mixing tank.

[0009] An inlet is arranged on the light-removing column.

[0010] The product column, the ester recovery column and the acetonitrile column are all provided with an outlet for the separation product of the liquid-phase ammonia-containing mixed product.

[0011] Optionally, the reflux ratio of the ester recovery column is 1-30.

[0012] Optionally, the theoretical tray number of the ester recovery column is 10-80.

[0013] Optionally, the ester recovery column has a top temperature of 80-200°C and an operating pressure of 200-1000 kPaA.

[0014] Optionally, the acetonitrile column has a reflux ratio of 1-50.

[0015] Optionally, the acetonitrile column has a theoretical plate number of 10-80.

[0016] Optionally, the acetonitrile column has a top temperature of 100-200°C and an operating pressure of 800-2000 kPaA.

[0017] Optionally, the light removal column has a reflux ratio of 200-1000.

[0018] Optionally, the light removal column has a theoretical plate number of 10-80.

[0019] Optionally, the light removal column has a top temperature of -20-60°C and an operating pressure of 200-900 kPaA.

[0020] Optionally, the azeotrope column has a reflux ratio of 1-10.

[0021] Optionally, the azeotrope column has a theoretical plate number of 10-80.

[0022] Optionally, the azeotrope column has a top temperature of 10-80°C and an operating pressure of 0.5-600 kPaA.

[0023] Optionally, the ammonia recovery column has a reflux ratio of 0.1-10.

[0024] Optionally, the ammonia recovery column has a theoretical plate number of 10-80.

[0025] Optionally, the ammonia recovery column has a top temperature of -20-60°C and an operating pressure of 0.5-600 kPaA.

[0026] Optionally, the separation column has a reflux ratio of 0.1-30.

[0027] Optionally, the separation column has a theoretical plate number of 10-80.

[0028] Optionally, the separation column has a top temperature of 10-80°C and an operating pressure of 0.5-600 kPaA.

[0029] Optionally, the product column has a reflux ratio of 0.01-20.

[0030] Optionally, the product column has a theoretical plate number of 10-80.

[0031] Optionally, the product column has a top temperature of 10-60°C and an operating pressure of 0.5-600 kPaA.

[0032] Optionally, the mixing tank is an adiabatic vessel with gas inlet below liquid level or a two-phase mixing pipeline with built-in nozzle or other type of gas-liquid mixer.

[0033] According to another aspect of the present application, there is provided a separation method of liquid-phase ammonia-containing mixed product, comprising:

[0034] passing the liquid-phase ammonia-containing mixed product into a reaction device for separation to obtain a separation product;

[0035] wherein the reaction device is selected from the separation device of the liquid-phase ammonia-containing mixed product as described above.

[0036] Optionally, the liquid-phase ammonia-containing mixed product comprises the following components in terms of molar composition:

[0037]

[0038] Optionally, the separation method comprises the following steps:

[0039] (1) passing the liquid-phase ammonia-containing mixed product into a light-removing column, and after fractionation, dimethyl ether at the top of the light-removing column is sent to a mixing tank;

[0040] (2) heavy components at the bottom of the light-removing column are sent to an ammonia recovery column, and unreacted ammonia gas is separated at the top of the ammonia recovery column, and heavy components at the bottom of the ammonia recovery column are sent to a separation column for separation, and light components containing acetonitrile, methanol and methyl acetate at the top of the separation column are sent to an azeotrope column, and after azeotrope separation, acetonitrile-methanol mixture is obtained at the bottom of the azeotrope column;

[0041] (3) the methanol-methyl acetate mixture obtained at the top of the azeotrope column is sent to an ester recovery column for rectification and separation, and the methanol-methyl acetate azeotrope obtained at the top of the ester recovery column is again sent to the azeotrope column for separation, and methyl acetate is obtained at the bottom of the ester recovery column;

[0042] (4) the heavy components at the bottom of the azeotrope column are sent to an acetonitrile column to destroy the azeotrope condition of acetonitrile-methanol, and methanol is obtained at the top of the acetonitrile column, and acetonitrile is obtained at the bottom of the acetonitrile column;

[0043] (5) the heavy components at the bottom of the separation column are sent to a product column for separation to obtain acetamide and waste water, wherein the waste water is sent to the mixing tank.

[0044] Optionally, the method using the device comprises the following steps:

[0045] 1) the separation raw material is first sent to a light-removing column 1, and dimethyl ether impurities are separated at the top of the column and a small amount of ammonia is entrained and sent to a mixing tank 8;

[0046] 2) Ammonia-containing impurities are absorbed by mixing with wastewater in the tank before being discharged;

[0047] 3) The material obtained from the bottom of the light tower 1 is sent to the ammonia recovery tower 2, where unreacted ammonia is separated at the top and the heavy material obtained from the bottom is sent to the separation tower 3.

[0048] 4) Separation tower 3 separates the material in the middle. The light component containing acetonitrile, methanol and methyl acetate is obtained at the top of the tower, and the heavy component containing water and acetyl is obtained at the bottom of the tower.

[0049] 5) The bottom material of separation tower 3 is separated in product tower 5 to obtain wastewater and acetamide. The wastewater is sent to mixing tank 8.

[0050] 6) The light material at the top of the separation tower 3 is sent to the azeotropic tower 4 and together with the circulating azeotrope, it serves as the separation feed for the azeotropic tower 4. A methanol-methyl acetate mixture is obtained at the top of the tower, and an acetonitrile-methanol mixture is obtained at the bottom of the tower.

[0051] 7) The top fraction of azeotropic column 4 is sent to ester recovery column 6 for high-pressure distillation. The methanol-methyl acetate high-pressure azeotrope is obtained at the top of the column and returned to azeotropic column 4 for further separation. Methyl acetate is obtained at the bottom of the column. The bottom product of azeotropic column 4 is sent to acetonitrile column 7, where the acetonitrile-methanol azeotropic condition is disrupted under high pressure. Methanol is obtained at the top of the column, and acetonitrile is obtained as a byproduct at the bottom.

[0052] According to another aspect of this application, the above-described separation apparatus is provided for the separation of precursors in the amination of methyl acetate to acetonitrile.

[0053] This application discloses a method for separating ammonia-containing liquid-phase mixed products. The method uses a liquid-phase product obtained after crude separation of an ammoniation product as raw material (the raw material's molar composition is 3.5-7.5% methyl acetate, 70-85% ammonia, 0.3-2.5% acetonitrile, 0.4-8.5% acetamide, 2.5-7.5% methanol, 0.5-3.5% water, and 0.001-0.05% dimethyl ether). The apparatus includes the following components:

[0054] The system consists of a light component removal tower 1, an ammonia recovery tower 2, a separation tower 3, an azeotropic tower 4, a product tower 5, an ester recovery tower 6, an acetonitrile tower 7, and a mixing tank 8. The raw material is first fed into the light component removal tower 1, where dimethyl ether impurities and a small amount of ammonia are separated at the top and sent to the mixing tank 8. In the mixing tank, the impurities are absorbed by the mixture with wastewater before being discharged. The bottom material from the light component removal tower 1 is sent to the ammonia recovery tower 2, where unreacted ammonia is separated at the top, and the heavy material at the bottom is sent to the separation tower 3. The separation tower 3 separates the material in half; the top part contains a light component with acetonitrile, methanol, and methyl acetate, and the bottom part contains a heavy component with water and acetylene. The bottom material is separated in the product tower 5 to obtain wastewater and acetamide; the wastewater is sent to the mixing tank 8. The light material from the top is sent to the azeotropic tower 4, where it, along with the recycled azeotrope, serves as the feed for the azeotropic tower 4 separation. A methanol-methyl acetate mixture is obtained at the top, and an acetonitrile-methanol mixture is obtained at the bottom. The top fraction from azeotropic column 4 is sent to ester recovery column 6 for high-pressure distillation. The top product is a methanol-methyl acetate high-pressure azeotrope, which is returned to azeotropic column 4 for further separation. The bottom product is methyl acetate. The bottom product from azeotropic column 4 is sent to acetonitrile column 7, where the acetonitrile-methanol azeotropic condition is disrupted under high pressure. Methanol is obtained at the top, and acetonitrile is obtained as a byproduct at the bottom.

[0055] The beneficial effects that this application can produce include:

[0056] The separation method for liquid-phase ammonia-containing mixed products provided in this application uses a liquid-phase product obtained after crude separation of an ammonia product as raw material. After steps of light impurity separation, light raw material recovery, sequential distillation, azeotropic separation, and high-pressure azeotropic breaking, acetamide main product, acetonitrile by-product, and recycled gas and liquid raw materials are obtained. The method also avoids the discharge of polluting gases by dissolving trace impurities and non-condensable gases in self-produced wastewater. The process is continuous and can be used as a pilot separation method for the ammonia production of acetonitrile from methyl acetate. It is environmentally friendly and suitable for large-scale continuous industrial operation. Attached Figure Description

[0057] Figure 1 This is a schematic diagram of the separation device for the liquid-phase ammonia-containing mixed product of Example 1 of this application.

[0058] in:

[0059] 1. Light weight removal tower; 2. Ammonia recovery tower; 3. Separation tower; 4. Azeotropic tower; 5. Product tower; 6. Ester recovery tower; 7. Acetonitrile tower; 8. Mixing tank. Detailed Implementation

[0060] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0061] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0062] Example 1

[0063] like Figure 1 The diagram shows a separation device for a liquid-phase ammonia-containing mixed product. The device includes: a light-weight removal tower 1, an ammonia recovery tower 2, a separation tower 3, an azeotropic tower 4, a product tower 5, an ester recovery tower 6, an acetonitrile tower 7, and a mixing tank 8. The light-weight removal 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 azeotropic tower 4, the top of the azeotropic tower 4 is connected to the ester recovery tower 6, and the top of the ester recovery tower 6 is connected to the azeotropic tower 4. The bottom of the azeotropic tower 4 is connected to the acetonitrile tower 7. The bottom of the separation tower 3 is connected to the product tower 5, and the top of the product tower 5 is connected to the mixing tank 8. The light-weight removal tower 1 has an inlet. The product tower 5, the ester recovery tower 6, and the acetonitrile tower 7 all have outlets for the separated products from the liquid-phase ammonia-containing mixed product. The mixing tank 8 is an insulated container with a gas inlet inserted below the liquid surface, a two-phase mixing pipe with a built-in nozzle, or another type of gas-liquid mixer.

[0064] Example 2

[0065] A liquid-phase ammonia-containing mixture (molar composition: methyl acetate 5.44%, ammonia 82.46%, acetonitrile 1.10%, acetamide 4.40%, methanol 5.49%, water 1.11%, dimethyl ether 0.0049%) was first fed into a light-weight removal tower 1. The tower's top pressure was 700 kPaA, top temperature 7°C, with 30 theoretical plates and a reflux ratio of 800. Waste gas with a dimethyl ether molar content of 28.19% was separated at the top of tower 1 and sent to a mixing tank 8, where it was adiabatically mixed and absorbed with wastewater before being discharged. The material obtained from the bottom of tower 1 was sent to ammonia recovery tower 2. The tower's top pressure was 300 kPaA, top temperature -8°C, with 30 theoretical plates and a reflux ratio of 1. Unreacted ammonia gas with a molar purity of 99.99% was separated at the top of recovery tower 2. The heavy material obtained from the bottom of recovery tower 2 was sent to tower 3. Separation column 3 has a top pressure of 110 kPaA and a top temperature of 53°C, with 30 theoretical plates and a reflux ratio of 1. Separation column 3 separates the material in the middle. The top of separation column 3 yields a light component containing acetonitrile, methanol, and methyl acetate, while the bottom of separation column 3 yields a heavy component containing water and acetyl. The bottom material of separation column 3 is sent to product column 5, which has a top pressure of 10 kPaA and a top temperature of 46°C, with 30 theoretical plates and a reflux ratio of 1. In product column 5, the material is separated to obtain wastewater and the target product acetamide. The wastewater is sent to mixing tank 8. The light material from the top of separation column 3 is sent to azeotropic column 4, where it, along with the circulating azeotrope, serves as the separation feed for azeotropic column 4. The top pressure of azeotropic column 4 is 103 kPaA and the top temperature of 54°C, with 30 theoretical plates and a reflux ratio of 15. A methanol-methyl acetate mixture is obtained at the top of azeotropic column 4, and an acetonitrile-methanol mixture is obtained at the bottom. The top fraction from azeotropic column 4 is sent to ester recovery column 6 for high-pressure distillation. Ester recovery column 6 has a top pressure of 603 kPaA, a top temperature of 110°C, 30 theoretical plates, and a reflux ratio of 3. The methanol-methyl acetate high-pressure azeotrope is obtained at the top of ester recovery column 6 and returned to azeotropic column 4 for further separation. Methyl acetate is obtained at the bottom of azeotropic column 4. The bottom product from azeotropic column 4 is sent to acetonitrile column 7. Acetonitrile column 7 has a top pressure of 1800 kPaA, a top temperature of 161°C, 40 theoretical plates, and a reflux ratio of 20. Under high-pressure conditions, the acetonitrile-methanol azeotropic condition is disrupted, resulting in methanol at the top of acetonitrile column 7 and acetonitrile as a byproduct at the bottom.

[0066] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A separation device for a liquid-phase ammonia-containing mixed products, characterized in that, The separation device includes: a light component removal tower (1), an ammonia recovery tower (2), a separation tower (3), an azeotropic tower (4), a product tower (5), an ester recovery tower (6), an acetonitrile tower (7), and a mixing tank (8); The bottom of the light-light removal tower (1) is connected to the ammonia recovery tower (2), and the bottom of the ammonia recovery tower (2) is connected to the separation tower (3); The top of the separation tower (3) is connected to the azeotropic tower (4), the top of the azeotropic tower (4) is connected to the ester recovery tower (6), and the top of the ester recovery tower (6) is connected to the azeotropic tower (4). The bottom of the azeotropic tower (4) is connected to the acetonitrile tower (7); The bottom of the separation tower (3) is connected to the product tower (5), and the top of the product tower (5) is connected to the mixing tank (8). The light-removal tower (1) is equipped with an inlet; The product tower (5), ester recovery tower (6) and acetonitrile tower (7) are all equipped with outlets for separating the ammonia-containing liquid phase mixture.

2. The separation device according to claim 1, characterized in that, The reflux ratio of the ester recovery tower (6) is 1~30; The theoretical number of plates in the ester recovery tower (6) is 10 to 80. The temperature at the top of the ester recovery tower (6) is 80~200 ℃ and the operating pressure is 200~1000 kPaA.

3. The separation device according to claim 1, characterized in that, The reflux ratio of the acetonitrile tower (7) is 1~50; The theoretical number of plates in the acetonitrile tower (7) is 10 to 80. The temperature at the top of the acetonitrile tower (7) is 100~200 ℃ and the operating pressure is 800~2000 kPaA.

4. The separation device according to claim 1, characterized in that, The reflux ratio of the light-light removal tower (1) is 200~1000; The theoretical number of plates in the light removal tower (1) is 10 to 80. The top temperature of the light-light removal tower (1) is -20~60 ℃, and the operating pressure is 200~900kPaA; The reflux ratio of the azeotropic tower (4) is 1~10; The theoretical number of plates in the azeotropic column (4) is 10 to 80. The top temperature of the azeotropic tower (4) is 10~80 ℃ and the operating pressure is 0.5~600kPaA.

5. The separation device according to claim 1, characterized in that, The reflux ratio of the ammonia recovery tower (2) is 0.1~10; The theoretical number of trays in the ammonia recovery tower (2) is 10 to 80. The temperature at the top of the ammonia recovery tower (2) is -20~60 ℃, and the operating pressure is 0.5~600kPaA; The reflux ratio of the separation tower (3) is 0.1~30; The theoretical number of plates in the separation tower (3) is 10 to 80. The top temperature of the separation tower (3) is 10~80 ℃ and the operating pressure is 0.5~600kPaA.

6. The separation device according to claim 1, characterized in that, The reflux ratio of the product tower (5) is 0.01~20; The theoretical number of plates in the product tower (5) is 10 to 80. The top temperature of the product tower (5) is 10~60 ℃ and the operating pressure is 0.5~600kPaA.

7. A method for separating ammonia-containing mixed products in the liquid phase, characterized in that, The separation method includes: The liquid-phase ammonia-containing mixed product is passed into a reaction apparatus and separated to obtain the separated product; The reaction apparatus is selected from the separation apparatus for liquid-phase ammonia-containing mixed products according to any one of claims 1 to 6.

8. The separation method according to claim 7, characterized in that, Based on molar composition, the liquid-phase ammonia-containing mixed product comprises the following components: Methyl acetate 3.5~7.5%; Ammonia 70-85%; Acetonitrile 0.3~2.5%; Acetamide 0.4~8.5%; Methanol 2.5~7.5%; Water 0.5~3.5%; Dimethyl ether 0.001~0.05%.

9. The separation method according to claim 7, characterized in that, The separation method includes the following steps: (1) The liquid-phase ammonia-containing mixed product is fed into the light-light product removal tower. After fractionation, the dimethyl ether at the top of the light-light product removal tower enters the mixing tank. (2) The heavy components at the bottom of the light component removal tower enter the ammonia recovery tower, and unreacted ammonia is separated at the top of the tower. The heavy components at the bottom of the ammonia recovery tower enter the separation tower for separation. The light components containing acetonitrile, methanol and methyl acetate are obtained at the top of the separation tower and enter the azeotropic tower. After azeotropic separation, the acetonitrile-methanol mixture is obtained at the bottom of the azeotropic tower. (3) The methanol-methyl acetate mixture obtained at the top of the azeotropic tower enters the ester recovery tower for distillation separation. The methanol-methyl acetate azeotrope obtained at the top of the ester recovery tower enters the azeotropic tower again for separation. Methyl acetate is obtained at the bottom of the ester recovery tower. (4) The heavy components at the bottom of the azeotropic tower enter the acetonitrile tower, which disrupts the azeotropic conditions of acetonitrile-methanol. Methanol is obtained at the top of the acetonitrile tower, and acetonitrile is obtained at the bottom of the acetonitrile tower. (5) The heavy components at the bottom of the separation tower enter the product tower for separation, yielding acetamide and wastewater, of which the wastewater enters the mixing tank.

10. The application of the separation apparatus according to any one of claims 1 to 6 in the separation of the precursor in the amination of methyl acetate to acetonitrile.

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