Separation device and separation method for liquid-phase ammonia-containing mixed product and application

Abstract

The invention discloses a separation device and a separation method for a liquid-phase ammonia-containing mixed product and application. The separation device comprises a light component removal tower, an ammonia recovery tower, a separation tower, an azeotropic tower, a product tower, an ester recovery tower, an acetonitrile tower and a mixing tank. A liquid-phase product obtained after crude separation of an ammoniation product is used as a raw material, an acetamide main product, an acetonitrile byproduct and recycled gas and liquid-phase raw materials are obtained through the steps of light impurity separation, light raw material recovery, sequential rectification, azeotropic separation and high-pressure azeotropic breaking, and trace impurity non-condensable gas is dissolved through self-produced wastewater; and pollution gas is prevented from being discharged. The separation method can be used for separation of the precursor for preparing acetonitrile 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 separation device and a separation method for a liquid phase ammonia-containing mixed product and an application thereof, belonging 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, there is a need for continuous research.

[0003] The two-step ammoniation and dehydration process of methyl acetate is a method for preparing acetonitrile with low cost and high product purity. The industrialization difficulty of the method lies in the separation and purification process of preparing acetamide by ammoniation of methyl acetate in the first step. The present invention provides a method for separating the ammoniation liquid phase mixture of the method, which has a continuous process, is environmentally friendly, and is suitable for large-scale continuous operation in industrialization. Summary of the invention

[0004] According to one aspect of the present application, a separation device for a liquid-phase ammonia-containing mixed product is provided, the separation device comprising: a lightness removal tower, an ammonia recovery tower, a separation tower, an azeotropic tower, a product tower, an ester recovery tower, an acetonitrile tower and a mixing tank;

[0005] The lightness removal tower is connected to an ammonia recovery tower, and the ammonia recovery tower is connected to a separation tower;

[0006] The top of the separation tower is connected to the azeotropic tower, the top of the azeotropic tower is connected to the ester recovery tower, and the top of the ester recovery tower is connected to the azeotropic tower;

[0007] The bottom of the azeotropic column is connected to the acetonitrile column;

[0008] The bottom of the separation tower is connected to the product tower, and the top of the product tower is connected to the mixing tank;

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

[0010] The product tower, ester recovery tower and acetonitrile tower are all provided with outlets for separation products of liquid phase ammonia-containing mixed products.

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

[0012] Optionally, the ester recovery tower has 10 to 80 theoretical plates.

[0013] Optionally, the top temperature of the ester recovery tower is 80-200° C., and the operating pressure is 200-1000 kPaA.

[0014] Optionally, the reflux ratio of the acetonitrile tower is 1-50.

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

[0016] Optionally, the top temperature of the acetonitrile tower is 100-200° C., and the operating pressure is 800-2000 kPaA.

[0017] Optionally, the reflux ratio of the lightness removal tower is 200-1000.

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

[0019] Optionally, the top temperature of the lightness removal tower is -20 to 60°C, and the operating pressure is 200 to 900 kPaA.

[0020] Optionally, the reflux ratio of the azeotropic tower is 1-10.

[0021] Optionally, the azeotropic tower has 10 to 80 theoretical plates.

[0022] Optionally, the top temperature of the azeotropic tower is 10-80° C., and the operating pressure is 0.5-600 kPaA.

[0023] Optionally, the reflux ratio of the ammonia recovery tower is 0.1-10.

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

[0025] Optionally, the top temperature of the ammonia recovery tower is -20 to 60°C, and the operating pressure is 0.5 to 600 kPaA.

[0026] Optionally, the reflux ratio of the separation tower is 0.1-30.

[0027] Optionally, the separation tower has 10 to 80 theoretical plates.

[0028] Optionally, the top temperature of the separation tower is 10-80° C., and the operating pressure is 0.5-600 kPaA.

[0029] Optionally, the reflux ratio of the product tower is 0.01-20.

[0030] Optionally, the product tower has 10 to 80 theoretical plates.

[0031] Optionally, the top temperature of the product tower is 10-60° C., and the operating pressure is 0.5-600 kPaA.

[0032] Optionally, the mixing tank is an insulated container with a gas phase inlet inserted below the liquid surface or a two-phase mixing pipe with a built-in nozzle or other types of gas-liquid mixer.

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

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

[0035] Wherein, the reaction device is selected from the above-mentioned separation device of the liquid phase ammonia-containing mixed product.

[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) The liquid ammonia-containing mixed product is passed into a light-removal tower, and after fractionation, the dimethyl ether at the top of the light-removal tower enters a mixing tank;

[0040] (2) the heavy components at the bottom of the light removal tower enter an ammonia recovery tower, unreacted ammonia is separated at the top of the tower, the heavy components at the bottom of the ammonia recovery 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 an azeotropic tower, and after azeotropic separation, an acetonitrile-methanol mixture is obtained at the bottom of the azeotropic tower;

[0041] (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, and methyl acetate is obtained at the bottom of the ester recovery tower;

[0042] (4) The heavy components at the bottom of the azeotropic tower enter the acetonitrile tower to destroy 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;

[0043] (5) The heavy components at the bottom of the separation tower enter the product tower for separation to obtain acetamide and waste water, wherein the waste water enters the mixing tank.

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

[0045] 1) The separated raw materials are first sent to the light removal tower 1, and the dimethyl ether impurities are separated at the top of the tower and a small amount of ammonia is entrained and sent to the mixing tank 8;

[0046] 2) Ammonia impurities are mixed with wastewater in the tank and then discharged;

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

[0048] 4) The separation tower 3 separates the material from the middle, and obtains the light components containing acetonitrile, methanol, and methyl acetate at the top of the tower, and obtains the heavy components containing water and acetyl 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, and 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, serves as the separation feed of the azeotropic tower 4, and a methanol-methyl acetate mixture is obtained at the top of the tower, and an acetonitrile-methanol mixture is obtained in the bottom of the tower;

[0051] 7) The top component of the azeotropic tower 4 is sent to the ester recovery tower 6, and is distilled and separated under high pressure to obtain methanol-methyl acetate high-pressure azeotrope at the top of the tower, which is returned to the azeotropic tower 4 for separation, and methyl acetate is obtained at the bottom of the tower. The bottom material of the azeotropic tower 4 is sent to the acetonitrile tower 7, and the acetonitrile-methanol azeotropic condition is destroyed under high pressure conditions, methanol is obtained at the top of the tower, and by-product acetonitrile is obtained at the bottom of the tower.

[0052] According to another aspect of the present application, there is provided an application of the above-mentioned separation device in the separation of the precursor in the preparation of acetonitrile by the amination of methyl acetate.

[0053] The present application discloses a method for separating a liquid phase ammonia-containing mixed product, using a liquid phase product obtained after a rough separation of an aminated product as a raw material (the raw material 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, 0.001-0.05% dimethyl ether), and the device comprises the following parts:

[0054] Light removal tower 1, ammonia recovery tower 2, separation tower 3, azeotropic tower 4, product tower 5, ester recovery tower 6, acetonitrile tower 7, mixing tank 8. The separated raw materials are first sent to the light removal tower 1, and the dimethyl ether impurities are separated at the top of the tower and a small amount of ammonia is entrained, and sent to the mixing tank 8, where they are mixed with wastewater for absorption and discharged. The material obtained at the bottom of the light removal tower 1 is sent to the ammonia recovery tower 2, and the unreacted ammonia is separated at the top of the tower. The heavy material obtained at the bottom of the tower is sent to the separation tower 3. The 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 the tower, and the heavy components containing water and acetyl are obtained at the bottom of the tower. The bottom material is separated in the product tower 5 to obtain wastewater and acetamide, and the wastewater is sent to the mixing tank 8. The light material at the top of the tower is sent to the azeotropic tower 4, and together with the circulating azeotrope, it is used as the separation feed of the azeotropic tower 4, and a methanol-methyl acetate mixture is obtained at the top of the tower, and an acetonitrile-methanol mixture is obtained in the bottom of the tower. The top component of azeotropic tower 4 is sent to ester recovery tower 6, where it is distilled and separated under high pressure, and methanol-methyl acetate high-pressure azeotrope is obtained at the top of the tower, which is returned to azeotropic tower 4 for separation, and methyl acetate is obtained at the bottom of the tower. The bottom material of azeotropic tower 4 is sent to acetonitrile tower 7, where the acetonitrile-methanol azeotropic condition is destroyed under high pressure, methanol is obtained at the top of the tower, and by-product acetonitrile is obtained at the bottom of the tower.

[0055] The beneficial effects of this application include:

[0056] The method for separating a liquid ammonia-containing mixed product provided in the present application uses a liquid product obtained after a rough separation of an amination product as a raw material, and obtains acetamide as a main product, acetonitrile as a by-product, and gaseous and liquid raw materials for recycling after the steps of light impurity separation - light raw material recovery - sequential distillation - azeotropic separation - high-pressure azeotropic breaking. The method also dissolves trace impurities and non-condensable gases in self-produced wastewater, thereby avoiding the continuous discharge of polluting gases. The method can be used for the separation of precursors in the preparation of acetonitrile by amination of methyl acetate, is environmentally friendly, and is suitable for large-scale continuous industrial operation. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0058] in:

[0059] 1. Lightness 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 DESCRIPTION

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

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

[0062] Example 1

[0063] like Figure 1 The figure shows a separation device for a liquid phase ammonia-containing mixed product, the separation device comprising: a light 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 removal tower 1 is connected to the ammonia recovery tower 2, 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, 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, the top of the product tower 5 is connected to the mixing tank 8; the light removal tower 1 is provided with an inlet; the product tower 5, the ester recovery tower 6 and the acetonitrile tower 7 are all provided with an outlet for the separation product of the liquid phase ammonia-containing mixed product. The mixing tank 8 is an insulated container with a gas phase inlet inserted below the liquid surface or a two-phase mixing pipeline or other type of gas-liquid mixer with a built-in nozzle.

[0064] Example 2

[0065] The liquid phase ammonia mixed product is first sent to the lightness removal tower 1 as the separation raw material (molar composition is methyl acetate 5.44%, ammonia 82.46%, acetonitrile 1.10%, acetamide 4.40%, methanol 5.49%, water 1.11%, dimethyl ether 0.0049%), the lightness removal tower 1 has a top pressure of 700kPaA, a top temperature of 7°C, 30 theoretical plates, and a reflux ratio of 800. Waste gas with a molar content of 28.19% of dimethyl ether is separated at the top of the separation tower 1 and sent to a mixing tank 8, 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 an ammonia recovery tower 2, the top pressure of the ammonia recovery tower 2 is 300kPaA, the top temperature of -8°C, 30 theoretical plates, and a reflux ratio of 1. 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 recovery tower 2 is sent to the separation tower 3. The top pressure of separation tower 3 is 110 kPaA, the top temperature is 53°C, 30 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 acetyl are obtained at the bottom of separation tower 3. The material at the bottom of separation tower 3 is sent to product tower 5, the top pressure of product tower 5 is 10 kPaA, the top temperature is 46°C, 30 theoretical plates are provided, and the reflux ratio is 1. The material is separated in product tower 5 to obtain waste water and target product acetamide, and the waste water is sent to mixing tank 8. The light material at the top of separation tower 3 is sent to azeotropic tower 4, and is used together with the circulating azeotrope as the separation feed of azeotropic tower 4, the top pressure of azeotropic tower 4 is 103 kPaA, the top temperature is 54°C, 30 theoretical plates are provided, and the reflux ratio is 15, and a methanol-methyl acetate mixture is obtained at the top of azeotropic tower 4, and an acetonitrile-methanol mixture is obtained in the bottom of the tower. The top component of azeotropic tower 4 is sent to ester recovery tower 6 for distillation separation under high pressure. The top pressure of ester recovery tower 6 is 603 kPaA, the top temperature is 110°C, 30 theoretical plates are provided, and the reflux ratio is 3. The methanol-methyl acetate high-pressure azeotrope is obtained at the top of ester recovery tower 6, and is returned to azeotropic tower 4 for separation, and methyl acetate is obtained at the bottom. The bottom material of azeotropic tower 4 is sent to acetonitrile tower 7. The top pressure of acetonitrile tower 7 is 1800 kPaA, the top temperature is 161°C, 40 theoretical plates are provided, and the reflux ratio is 20. The acetonitrile-methanol azeotropic condition is destroyed under high pressure conditions, methanol is obtained at the top of acetonitrile tower 7, and by-product acetonitrile is obtained at the bottom of acetonitrile tower 7.

[0066] 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 separation device for a liquid phase ammonia-containing mixed product, characterized in that: The separation device comprises: a lightness 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-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 column (4) is connected to the acetonitrile column (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 provided with an inlet; The product tower (5), the ester recovery tower (6) and the acetonitrile tower (7) are all provided with outlets for separation products of the liquid phase ammonia-containing mixed product.

2. The separation device according to claim 1, characterized in that: The reflux ratio of the ester recovery tower (6) is 1 to 30; Preferably, the number of theoretical plates of the ester recovery tower (6) is 10 to 80; Preferably, the top temperature of the ester recovery tower (6) is 80-200°C, 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 column (7) is 1 to 50; Preferably, the acetonitrile column (7) has a theoretical plate number of 10 to 80; Preferably, the top temperature of the acetonitrile tower (7) is 100-200° C., and the operating pressure is 800-2000 kPaA.

4. The separation device according to claim 1, characterized in that: The reflux ratio of the lightness removal tower (1) is 200 to 1000; 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; Preferably, the reflux ratio of the azeotropic column (4) is 1 to 10; Preferably, the number of theoretical plates of the azeotropic column (4) is 10 to 80; Preferably, the top temperature of the azeotropic tower (4) is 10-80°C, and the operating pressure is 0.5-600 kPaA.

5. The separation 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; Preferably, the reflux ratio of the separation tower (3) is 0.1 to 30; Preferably, the separation tower (3) has a theoretical plate number of 10 to 80; Preferably, the top temperature of the separation tower (3) is 10 to 80° C., and the operating pressure is 0.5 to 600 kPaA.

6. The separation device according to claim 1, characterized in that: The reflux ratio of the product tower (5) is 0.01 to 20; Preferably, the product column (5) has a theoretical plate number of 10 to 80; Preferably, the top temperature of the product tower (5) is 10-60°C, and the operating pressure is 0.5-600 kPaA.

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

8. The separation method according to claim 7, characterized in that In terms of molar composition, the liquid phase ammonia-containing mixed product includes the following components:

9. The separation method according to claim 7, characterized in that The separation method comprises the following steps: (1) The liquid ammonia-containing mixed product is passed into a light-removal tower, and after fractionation, the dimethyl ether at the top of the light-removal tower enters a mixing tank; (2) the heavy components at the bottom of the light removal tower enter an ammonia recovery tower, unreacted ammonia is separated at the top of the tower, the heavy components at the bottom of the ammonia recovery 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 an azeotropic tower, and after azeotropic separation, an 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, and 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 to destroy 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 to obtain acetamide and waste water, wherein the waste water enters the mixing tank.

10. Use of the separation device according to any one of claims 1 to 6 in the separation of the precursor in the preparation of acetonitrile by the amination of methyl acetate.

Images