Equipment and method for separating DMAMP and water azeotrope through extractive distillation

Abstract

The invention discloses equipment and a method for extracting, rectifying and separating DMAMP and water azeotrope, one or more of N, N-diethyl acetamide, N, N-diethyl aniline, N, N-dimethylaniline, hexamethylenediamine, N-methyl pyrrolidone and ethylene glycol are adopted as an extracting agent, and the extracting agent is added, so that the separation degree of DMAMP and water can be effectively changed, and the separation efficiency of DMAMP and water is improved. Through two-tower operation of the extractive distillation tower and the extractant recovery tower, efficient separation of azeotrope is realized. The extracting agent and a DMAMP and water azeotrope enter an extractive distillation tower, and the water purity gt is separated from the tower top of the extractive distillation tower; a mixture of DMAMP and an extraction agent is contained in a tower kettle and enters an extraction agent recovery tower to be separated, and the purity gt is obtained at the top of the extraction agent recovery tower; 99.0 wt% of DMAMP and a tower kettle extraction agent enter an extractive distillation tower for cyclic utilization; the device solves the problem that the azeotropic system cannot be separated by common rectification, has the advantages of simple structure, convenience in operation, economy, environmental protection and the like, and realizes effective separation of DMAMP and water azeotrope.

Description

Technical Field

[0001] The invention relates to a liquid separation technology, in particular to a method for separating azeotropes of DMAMP and water by extraction and rectification. Background Art

[0002] 2-Dimethylamino-2-methyl-1-propanol (DMAMP for short) is a colorless liquid with a special ammonia smell. It is an important organic chemical product and is widely used in the fields of medicine, dyes, and chemicals. In the pharmaceutical field, as an important organic synthesis intermediate, 2-dimethylamino-2-methyl-1-propanol can be used to synthesize a variety of drugs, such as beta-receptor blockers, antihypertensive drugs, etc. In the dye field, it can be used as a dye intermediate for the synthesis of various organic dyes, and has good stability and light resistance. In the chemical field, it can be used as a surfactant, preservative, multifunctional coating, etc., and has good solubility and permeability.

[0003] At present, most DMAMP products on the market are solutions containing about 20% water. High-purity DMAMP products are more difficult to prepare and have higher product prices. DMAMP products are more difficult to separate when they contain water. Since DMAMP and water form azeotropes during the distillation process, the azeotrope composition is 24wt% DMAMP and 76wt% water, and the azeotropic point is 98.5°C. Simple distillation methods cannot achieve effective separation, so special separation methods are required. Summary of the invention

[0004] In view of the above-mentioned defects or deficiencies in the prior art, it is desirable to provide an apparatus and method for separating azeotropes of DMAMP and water by extractive distillation.

[0005] According to the technical solution provided in the embodiment of the present application, an extractive distillation device for separating azeotropes of DMAMP and water comprises an extractive distillation tower, an azeotrope feed port and an extractant feed port are provided on the side of the extractive distillation tower, a recovery port and a water sampling port are provided on the other side, and a discharge port and a reflux port are provided at the top and bottom, respectively, the azeotrope feed port and the extractant feed port are connected to the azeotrope feed pipeline and the extractant feed pipeline, respectively, the discharge port is connected in series with the tower top condenser A and the tower top reflux tank A through a pipeline, and the tower top reflux tank is connected to the water sampling port through a pipeline; The recovery port is connected to the extractant recovery tower through a pipeline and is connected in parallel to the reflux port through a parallel pipeline, and the tower kettle reboiler A and the tower kettle reflux pump are connected in series in sequence on the parallel pipeline; The extractant recovery tower is provided with a connection port connected to the extractive distillation tower on the side, a product outlet and an extractant recovery port on the other side, and a discharge port A and a reflux port A are provided on the top and bottom respectively; a tower top condenser B and a tower top reflux tank B are connected in series in sequence through a pipeline between the discharge port A and the product outlet, a tower bottom reboiler and a tower bottom reflux pump are connected in series between the extractant recovery port and the reflux port A through a pipeline, and the extractant recovery port is also connected in parallel to the extractant feed port of the extractive distillation tower through a pipeline, and a feed heat exchanger is installed on the pipeline; The outlets of the top condenser A and the tower top condenser B are respectively connected to an external vacuum system by external pipes.

[0006] A method for separating azeotropes of DMAMP and water by extractive distillation, The following steps are involved: The azeotrope of DMAMP and water is preheated in the feed heat exchanger and enters the extractive distillation tower from the bottom, the extractant enters the extractive distillation tower from the top, the materials are separated in the extractive distillation tower, water is evaporated from the top of the extractive distillation tower, passes through the top condenser, and enters the top reflux tank, part of the water is refluxed to the extractive distillation tower, part of the water is extracted, and the mixture of DMAMP and the extractant in the bottom of the tower enters the extractant recovery tower for separation; The product and the extractant are separated in the extractant recovery tower. The product DMAMP is evaporated from the top of the extractant recovery tower, passes through the top condenser, and enters the top reflux tank. Part of the product is refluxed to the extractant recovery tower, and part is produced as the DMAMP product. The extractant in the bottom of the tower is cooled by heat exchange with the components to be separated in the feed heat exchanger, and then enters the extractive distillation tower from the upper part, and the extractant is recycled.

[0007] In the present invention, further, the extractant is one or more of N,N-diethylacetamide, N,N-diethylaniline, N,N-dimethylaniline, hexamethylenediamine, N-methylpyrrolidone and ethylene glycol.

[0008] In the present invention, further, the mass ratio of the extractant to the azeotropic mixture of DMAMP and water is 1.8-2.5:1.

[0009] In the present invention, further, the extractive distillation tower is operated under negative pressure, the vacuum degree is -80kPa~-95kPa, and the reflux ratio is 0.5~2:1.

[0010] In the present invention, further, the extractant recovery tower is operated under negative pressure, the vacuum degree is -90kPa~-95kPa, and the reflux ratio is 1~4:1.

[0011] In the present invention, further, the number of theoretical plates of the extractive distillation tower is 30-40, the number of theoretical plates of the extractant recovery tower is 20-30, the extractant feed position is 20-30, the DMAMP and water mixture feed position is 5-10, and the extractant recovery tower feed position is 10-15.

[0012] In the present invention, further, the purity of the water produced from the top of the extractive distillation tower is >99.2wt%, and the purity of the top product of the extractant recovery tower is >99.0wt%.

[0013] In summary, the beneficial effects of this application are: (1) This process can achieve efficient separation of DMAMP and water azeotropes. After separation, the purity of the product is >99.0wt% and the purity of water is >99.2wt%; (2) The present invention uses N,N-diethylacetamide, N,N-diethylaniline, N,N-dimethylaniline, hexamethylenediamine, N-methylpyrrolidone and ethylene glycol as extractants, which significantly increases the relative volatility of the azeotrope; (3) The extractant can be recycled, and the recovery rate of the extractant is >99%; (4) The recovered extractant and the mixture to be separated are heat exchanged and then enter the extraction distillation tower respectively, thereby improving heat utilization and reducing energy consumption; (5) The process of the present invention is simple, economical, environmentally friendly and flexible to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings: Figure 1 Flow chart of the process for working of the present invention.

[0015] Numbers in the figure: Extraction distillation tower-1, extraction agent recovery tower-2, tower top condenser-6, tower top reflux tank-8, tower top condenser-7, tower top reflux tank-9, tower bottom reboiler-3, tower bottom reboiler-4, feed heat exchanger-5, tower bottom reflux pump-10, tower bottom reflux pump-11; The arrows in the figure indicate the direction of material flow. DETAILED DESCRIPTION

[0016] The present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It is also necessary to explain that, for ease of description, only the parts related to the invention are shown in the accompanying drawings.

[0017] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0018] Embodiment 1: The feed temperature of DMAMP and water azeotrope in the extractive distillation tower is 60°C, the flow rate is 60kg / h, the feed position is the 6th tower plate, the DMAMP content is 24%, the water content is 76%, the feed temperature of the extractant N,N-diethylaniline is 94°C, the flow rate is 120kg / h, the feed position is the 23rd tower plate, the theoretical number of plates of the extractive distillation tower is 35, the vacuum degree is -85kPa, the top temperature is 51.2~53.6°C, the bottom temperature is 117.1~119.5°C, the reflux ratio is 2:1, the theoretical number of plates of the extractant recovery tower is 26, the feed position is the 12th tower plate, the vacuum degree is -92kPa, the top temperature is 89.2~91.5°C, the bottom temperature is 125.7~128.0°C, and the reflux ratio is 3:1.

[0019] The purity of water after distillation is 99.3%, and the purity of DAMP product after separation is 99.2%.

[0020] Embodiment 2: The feed temperature of DMAMP and water azeotrope in the extractive distillation tower is 58°C, the flow rate is 60kg / h, the feed position is the 6th tower plate, the DMAMP content is 24%, the water content is 76%, the feed temperature of the extractant N-methylpyrrolidone is 90°C, the flow rate is 135kg / h, the feed position is the 23rd tower plate, the theoretical number of plates of the extractive distillation tower is 35, the vacuum degree is -85kPa, the top temperature is 51.2~53.6°C, the bottom temperature is 115.2~117.4°C, the reflux ratio is 2:1, the theoretical number of plates of the extractant recovery tower is 26, the feed position is the 12th tower plate, the vacuum degree is -92kPa, the top temperature is 89.2~91.5°C, the bottom temperature is 122.8~125.2°C, and the reflux ratio is 4:1.

[0021] The purity of water after distillation is 99.5%, and the purity of DAMP product after separation is 99.6%.

[0022] Embodiment 3: The feed temperature of DMAMP and water azeotrope in the extractive distillation tower is 55°C, the flow rate is 60kg / h, the feed position is the 6th tower plate, the DMAMP content is 24%, the water content is 76%, the feed temperature of the extractant N,N-diethylacetamide is 87°C, the flow rate is 110kg / h, the feed position is the 23rd tower plate, the theoretical number of plates of the extractive distillation tower is 35, the vacuum degree is -85kPa, the top temperature is 51.2~53.6°C, the bottom temperature is 107.5~109.8°C, the reflux ratio is 2:1, the theoretical number of plates of the extractant recovery tower is 26, the feed position is the 12th tower plate, the vacuum degree is -92kPa, the top temperature is 89.2~91.5°C, the bottom temperature is 118.9~121.2°C, and the reflux ratio is 3:1.

[0023] The purity of water after distillation is 99.2%, and the purity of DAMP product after separation is 99.1%.

[0024] The above description is only an explanation of the preferred embodiments of the present application and the technical principles and other schemes used. At the same time, the scope of the invention involved in the present application is not limited to the technical scheme formed by a specific combination of the above technical features, but also includes other technical schemes formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with the technical features with similar functions disclosed in the present application (but not limited to) to form a technical scheme.

Claims

1. An apparatus for extractive distillation separation of DMAMP and water azeotropes, comprising an extractive distillation tower (1), characterized in that: The extractive distillation tower (1) is provided with an azeotrope feed port and an extractant feed port on one side, a recovery port and a water sampling port on the other side, and a discharge port and a reflux port on the top and bottom respectively. The azeotrope feed port and the extractant feed port are connected to the azeotrope feed pipeline and the extractant feed pipeline respectively. The discharge port is connected in series with the tower top condenser A (6) and the tower top reflux tank A (8) through a pipeline. The tower top reflux tank (8) is connected to the water sampling port through a pipeline. The recovery port is connected to the extractant recovery tower (2) through a pipeline and is connected in parallel to the reflux port through a parallel pipeline, and the tower bottom reboiler A (3) and the tower bottom reflux pump (10) are connected in series in sequence on the parallel pipeline; The extractant recovery tower (2) is provided with a connection port connected to the extractive distillation tower (1) on one side, a product outlet and an extractant recovery port on the other side, and a discharge port A and a reflux port A on the top and bottom respectively; a tower top condenser B (7) and a tower top reflux tank B (9) are connected in series via a pipeline between the discharge port A and the product outlet, a tower bottom reboiler (4) and a tower bottom reflux pump (11) are connected in series via a pipeline between the extractant recovery port and the reflux port A, and the extractant recovery port is also connected in parallel to the extractant feed port of the extractive distillation tower (1) via a pipeline, and a feed heat exchanger (5) is installed on the pipeline; The outlets of the top condenser A (6) and the tower top condenser B (7) are respectively connected to an external vacuum system through external pipes.

2. A method for separating DMAMP and water azeotrope by extractive distillation, characterized in that: The following steps are involved: The azeotrope of DMAMP and water is preheated in a feed heat exchanger (5) and then enters an extractive distillation tower (1) from the bottom. The extractant enters the extractive distillation tower (1) from the top. The materials are separated in the extractive distillation tower (1). Water is evaporated from the top of the extractive distillation tower (1) and enters a top reflux tank (8) through a top condenser (6). Part of the water is refluxed to the extractive distillation tower (1), and part of the water is extracted. The mixture of DMAMP and the extractant in the bottom of the tower enters an extractant recovery tower (2) for separation. The product and the extractant are separated in the extractant recovery tower (2). The product DMAMP is evaporated from the top of the extractant recovery tower (2), passes through the top condenser (7), and enters the top reflux tank (9). A portion of the product is refluxed to the extractant recovery tower (2), and a portion is withdrawn as the DMAMP product. The extractant in the bottom of the tower is cooled by heat exchange with the components to be separated in the feed heat exchanger (5), and then enters the extractive distillation tower (1) from the top. The extractant is recycled.

3. The method for separating DMAMP and water azeotrope by extractive distillation according to claim 2, wherein: The extractant is one or more of N,N-diethylacetamide, N,N-diethylaniline, N,N-dimethylaniline, hexamethylenediamine, N-methylpyrrolidone and ethylene glycol.

4. according to the method for separating DMAMP and water azeotrope by extractive distillation according to claim 2, it is characterized in that: The mass ratio of the extractant to the azeotropic mixture of DMAMP and water is 1.8-2.5:

1.

5. according to the method for separating DMAMP and water azeotrope by extractive distillation according to claim 2, it is characterized in that: The extractive distillation tower is operated under negative pressure, with a vacuum degree of -80kPa~-95kPa and a reflux ratio of 0.5~2:

1.

6. A method for separating DMAMP and water azeotrope by extractive distillation according to claim 2, characterized in that: The extractant recovery tower is operated under negative pressure, with a vacuum degree of -90kPa~-95kPa and a reflux ratio of 1~4:

1.

7. A method for separating DMAMP and water azeotrope by extractive distillation according to claim 2, characterized in that: The theoretical plate number of the extractive distillation tower is 30-40, the theoretical plate number of the extractant recovery tower is 20-30, the extractant feed position is 20-30, the DMAMP and water mixture feed position is 5-10, and the extractant recovery tower feed position is 10-15.

8. A method for separating DMAMP and water azeotrope by extractive distillation according to claim 2, characterized in that: The purity of the produced water from the top of the extractive distillation tower is >99.2wt%, and the purity of the top product of the extractant recovery tower is >99.0wt%.

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