System for synthesizing high-purity ethyl acetate by using waste liquid

Abstract

The system is characterized in that a first grating pool is provided with a waste solvent ethanol feeding pipeline, a second grating pool is provided with an acetic acid waste liquid feeding pipeline, a discharging pipeline of the first grating pool and a discharging pipeline of the second grating pool are connected with a feeding port of an evaporation tank, a vaporized material discharging port of the evaporation tank is communicated with a feeding port of a reactive distillation tower, and a discharging port of the reactive distillation tower is communicated with a discharging port of the reactive distillation tower. A tower top discharge hole of the reactive distillation tower is communicated with a feed hole of the fractional condenser; an oil phase discharge hole of the fractional condenser is communicated with a reflux inlet of the reactive distillation tower; the fractional condenser is provided with a water phase discharge port, a gas phase discharge port of the fractional condenser is communicated with a feed port of the first cooler, a discharge port of the first cooler is communicated with a feed port of the washing tank, a discharge port of the washing tank is communicated with a feed port of the extractive distillation tower, and a tower side discharge port of the extractive distillation tower is communicated with a feed port of the second cooler. And the second cooler is provided with an ethyl acetate discharging pipeline. The system successfully achieves the effects of vaporizing feeding impurity removal and reactive distillation dehydration, and can solve the problem of insufficient purity of waste solvent ethanol and acetic acid waste liquid as raw materials.

Description

Technical Field

[0001] The utility model belongs to the field of industrial production and synthesis of ethyl acetate, and in particular relates to a system for synthesizing high-purity ethyl acetate by utilizing waste liquid. Background Art

[0002] Ethyl acetate is a widely used fine chemical product with excellent solubility and quick drying properties. It has a wide range of uses. It is a very important organic chemical raw material and an excellent industrial solvent. It is widely used in the production of cellulose acetate, ethyl cellulose, chlorinated rubber, ethylene resin, cellulose acetate resin, synthetic rubber, coatings and paints.

[0003] Most domestic companies use the direct esterification method of ethanol and acetic acid to produce ethyl acetate. This method has high requirements on the purity of ethanol and acetic acid raw materials. The waste solvent ethanol and acetic acid waste liquid from the pharmaceutical industry contain not only impurities such as suspended solids, but also drug residues and a large amount of water. According to conventional practice, the waste solvent ethanol and acetic acid waste liquid need to be purified and recovered before being used in the production of ethyl acetate, which is costly. However, it is difficult to directly use waste solvents and waste liquids to continuously produce ethyl acetate. There is a problem of low production efficiency due to insufficient raw material purity. Therefore, another new ethyl acetate synthesis system is urgently needed to solve the above problems. Utility Model Content

[0004] Based on the content in the background technology, the present application discloses a system for synthesizing high-purity ethyl acetate using waste liquid, which includes a first grid tank, a second grid tank, an evaporation tank, a reactive distillation tower, a partial condenser, an adsorption tank, a first cooler, a washing tank, an extractive distillation tower and a second cooler;

[0005] The first grid pool is provided with a waste solvent ethanol feed pipeline, the second grid pool is provided with an acetic acid waste liquid feed pipeline, a filter grid is provided in the grid pool, the discharge pipeline of the first grid pool and the discharge pipeline of the second grid pool are combined and connected to the feed port of the evaporation tank, the vaporized material discharge port at the top of the evaporation tank is connected to the lower feed port of the reaction distillation tower through a pipeline, and the bottom of the evaporation tank is provided with a heavy component impurity discharge port;

[0006] An ethanol liquid feed pipeline is arranged in the middle of the reaction distillation tower, a composite catalyst is loaded in the reaction distillation tower, a top discharge port of the reaction distillation tower is connected with a feed port of a partial condenser through a pipeline; an oil phase discharge port of the partial condenser is connected with a reflux port of the reaction distillation tower through a pipeline;

[0007] A water phase discharge port is also provided at the bottom of the dephlegmator, a gas phase discharge port at the top of the dephlegmator is connected with the feed port of the first cooler through a pipeline, the discharge port of the first cooler is connected with the feed port of the washing tank through a pipeline, a saturated sodium carbonate solution is contained in the washing tank, the discharge port of the washing tank is connected with the feed port in the middle of the extractive distillation tower through a pipeline, an extractant feed pipeline is provided at the top of the extractive distillation tower, a tower side discharge port of the extractive distillation tower is connected with the feed port of the second cooler through a pipeline, and an ethyl acetate discharge pipeline is provided on the second cooler.

[0008] Furthermore, an adsorption tank is also arranged on the connecting pipeline between the oil phase discharge port of the fractionator and the reflux port of the reaction distillation tower. The oil phase discharge port of the fractionator is connected with the feed port of the adsorption tank through the pipeline, and the discharge port of the adsorption tank is connected with the reflux port of the reaction distillation tower through the pipeline. The adsorption tank is filled with SAP resin or 5A molecular sieve.

[0009] Furthermore, the system for synthesizing high-purity ethyl acetate using waste liquid also includes an extractant regeneration tower and a third cooler, the lower discharge port of the extractive distillation tower is connected to the feed port of the extractive distillation tower through a pipeline, the discharge circulation port of the extractive regeneration tower is connected to the extractive agent feed pipeline of the extractive distillation tower through a pipeline, the tower side discharge port of the extractive agent regeneration tower is connected to the feed port of the third cooler through a pipeline, and the third cooler is provided with a wastewater discharge pipeline.

[0010] Pumps can be installed on the pipelines in the above systems to ensure smooth transportation of materials.

[0011] Preferably, a total of 42 tower plates are arranged in the reaction distillation tower, the lower feed inlet of the reaction distillation tower is located at the 35th tower plate of the reaction distillation tower, and the end of the ethanol liquid feed pipeline is located at the 16th tower plate of the reaction distillation tower; a total of 28 tower plates are arranged in the extractive distillation tower, the feed inlet of the extractive distillation tower is located at the 15th tower plate of the extractive distillation tower, and the end of the extractant feed pipeline is located at the 9th tower plate of the extractive distillation tower, and the above tower plates are all counted from top to bottom.

[0012] Through the above technical solution, the utility model at least includes the following beneficial effects:

[0013] Since the esterification reaction of ethanol and acetic acid is a reversible reaction, the reactive distillation tower can continuously take away the required reaction products, thereby promoting the reaction to realize the continuous production of ethyl acetate synthesis. Importantly, in the present application, through the cooperation of equipment such as an evaporator, a condenser and an adsorption tank, the effect of "vaporization feed impurity removal + reactive distillation dehydration" is successfully achieved, which can solve the problem of insufficient purity of waste solvent ethanol and acetic acid waste liquid as raw materials, and greatly improve the production efficiency of synthesizing ethyl acetate using waste solvents and waste liquids. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Schematic diagram of a system for synthesizing high-purity ethyl acetate using waste liquid in an embodiment of the present application. DETAILED DESCRIPTION

[0015] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. These drawings are simplified schematic diagrams that only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the structures related to the present invention.

[0016] In the description of this application, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "rear", etc. indicating the orientation or positional relationship, they are based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship are only used for exemplary description and cannot be understood as limiting this patent; if there are terms such as "first", "second", etc., they are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second", etc. may explicitly or implicitly include one or more of the said features. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to the specific circumstances.

[0017] In the description of the utility model, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "provided with", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the utility model can be understood according to specific circumstances.

[0018] refer to Figure 1 A system for synthesizing high-purity ethyl acetate using waste liquid, comprising a first grid pool 1, a second grid pool 2, an evaporation tank 3, a reaction distillation tower 4, a partial condenser 5, an adsorption tank 6, a first cooler 11, a washing tank 7, an extraction distillation tower 8 and a second cooler 12;

[0019] The first grid pool 1 is provided with a waste solvent ethanol feed pipeline 101, the second grid pool 2 is provided with an acetic acid waste liquid feed pipeline 201, a filter grid is provided in the grid pool, the discharge pipeline of the first grid pool 1 and the discharge pipeline of the second grid pool 2 are combined and connected to the feed port of the evaporation tank 3, the vaporized material discharge port 301 at the top of the evaporation tank 3 is connected to the lower feed port of the reaction distillation tower 4 through a pipeline, and the bottom of the evaporation tank 3 is provided with a heavy component impurity discharge port 302;

[0020] An ethanol liquid feed pipeline 401 is provided in the middle of the reaction distillation tower 4, a composite catalyst is loaded in the reaction distillation tower 4, and the top discharge port of the reaction distillation tower 4 is connected to the feed port of the dephlegmator 5 through a pipeline; the oil phase discharge port 501 of the dephlegmator 5 is connected to the reflux port 402 of the reaction distillation tower 4 through a pipeline;

[0021] A water phase discharge port 502 is also provided at the bottom of the dephlegmator 5, and a gas phase discharge port 503 at the top of the dephlegmator 5 is connected with the feed port of the first cooler 11 through a pipeline, and the discharge port of the first cooler 11 is connected with the feed port of the washing tank 7 through a pipeline. The washing tank 7 contains a saturated sodium carbonate solution, and the discharge port of the washing tank 7 is connected with the feed port in the middle of the extractive distillation tower 8 through a pipeline. An extractant feed pipeline 801 is provided at the upper part of the extractive distillation tower 8, and a tower side discharge port of the extractive distillation tower 8 is connected with the feed port of the second cooler 12 through a pipeline, and an ethyl acetate discharge pipeline 1201 is provided on the second cooler 12.

[0022] In a further embodiment, an adsorption tank 6 is also provided on the connecting pipeline between the oil phase discharge port 501 of the dephlegmator 5 and the reflux port 402 of the reaction distillation tower 4, the oil phase discharge port 501 of the dephlegmator 5 is connected with the feed port of the adsorption tank 6 through the pipeline, the discharge port of the adsorption tank 6 is connected with the reflux port 402 of the reaction distillation tower 4 through the pipeline, and the adsorption tank 6 is filled with SAP resin or 5A molecular sieve.

[0023] The system for synthesizing high-purity ethyl acetate using waste liquid also includes an extractant regeneration tower 9 and a third cooler 13. The lower discharge port of the extracting distillation tower 8 is connected to the feed port of the extracting agent regeneration tower 9 through a pipeline, the discharge circulation port 901 of the extracting agent regeneration tower 9 is connected to the extracting agent feed pipeline 801 of the extracting distillation tower 8 through a pipeline, and the tower side discharge port of the extracting agent regeneration tower 9 is connected to the feed port of the third cooler 13 through a pipeline, and the third cooler 13 is provided with a wastewater discharge pipeline 1301.

[0024] Pumps can be installed on the pipelines in the above systems to ensure smooth transportation of materials.

[0025] In a specific embodiment, a total of 42 tower plates are arranged in the reaction distillation tower 4, the lower feed port of the reaction distillation tower 4 is located at the 35th tower plate of the reaction distillation tower 4, and the end of the ethanol liquid feed pipeline 401 is located at the 16th tower plate of the reaction distillation tower 4; a total of 28 tower plates are arranged in the extractive distillation tower 8, the feed port of the extractive distillation tower 8 is located at the 15th tower plate of the extractive distillation tower 8, and the end of the extractant feed pipeline 801 is located at the 9th tower plate of the extractive distillation tower 8, and the above tower plates are all counted from top to bottom.

[0026] The method of using the above-mentioned system for synthesizing high-purity ethyl acetate using waste liquid (including working principle) is as follows:

[0027] S1. After the large suspended solids and solid impurities are removed from the waste solvent ethanol with an ethanol content of 90% and the waste acetic acid liquid with an acetic acid content of 78%, the waste solvent ethanol with an ethanol content of 90% and the waste acetic acid liquid with an acetic acid content of 78% are respectively passed through the first grid pool 1 and the second grid pool 2, and then mixed and sent to the evaporation tank 3, and the outlet temperature of the evaporation tank 3 is controlled to be 122°C by heating and pressurizing to ensure that the azeotropic mixture of ethanol and acetic acid can evaporate and vaporize; the above percentages and the following percentages are all mass percentages.

[0028] S2. The evaporated material in the evaporation tank 3 directly enters the reaction distillation tower 4 from the lower part of the tower, specifically through the 35th tower plate. The following tower plates are all counted from top to bottom. The heavy component impurities in the evaporation tank 3 are regularly extracted from the system. The total number of tower plates of the reaction distillation tower 4 is 42. The middle part of the reaction distillation tower 4, specifically the 16th tower plate, is sprayed and injected with ethanol liquid by a pump. The ethanol liquid has two functions: one is to control the reaction temperature and the gas-liquid balance of the distillation reaction tower together with the top reflux material. The reaction temperature is controlled at 79° C., and the other is to control the acid-to-alcohol feed ratio. Excess ethanol is purely beneficial to the reaction. The acid-to-alcohol ratio of the whole tower is controlled to be 1:1.6 by mass. The ethanol liquid sprayed and injected in the middle part of the reaction distillation tower 4 also contains 7% of 2-methylpentane. This component can preferentially form an azeotrope with the ethyl acetate generated by the reaction, so that the ethyl acetate is more easily distilled out, which can reduce the load of the reaction distillation tower 4.

[0029] The reaction distillation tower 4 is filled with a composite catalyst, which is prepared by impregnating NKC-9 macroporous strong acidic cation exchange resin in a composite solution containing MnCl2 and NaHSO3, adding Al2O3 powder to form a dispersed system, centrifugally stirring and mixing evenly, and then drying and heat treating. The weight ratio of MnCl2 to NaHSO3 in the composite solution is 1.3:1, and the weight ratio of Mn in the composite solution is 1.3:1. 2+ The ion concentration is 0.9 mol / L, the amount of Al2O3 powder added is 1.5 times the weight of the resin, and the NKC-9 macroporous strong acid cation exchange resin needs to be acid-washed before impregnation to remove impurities and activate the resin. The heat treatment temperature after drying is 70°C.

[0030] In the composite catalyst, NKC-9 macroporous strong acidic cation exchange resin is the main catalytic carrier. With the help of NaHSO3, Mn 2+ It can be stably adsorbed and fixed in the NKC-9 macroporous strong acid cation exchange resin in the form of a complex, and can react with the functional groups of the ion exchange resin to form a new strong acid center, thereby improving the stability and activity of the catalyst; and Al2O3 can also form a stable supporting structure with the NKC-9 macroporous strong acid cation exchange resin, which can provide it with a larger surface area and active sites to improve the reaction activity and selectivity of the catalyst. Under these joint action mechanisms, the composite catalyst has high catalytic performance and stability.

[0031] The steam material at the top of the reaction distillation tower 4 enters the condenser 5, and the oil phase in the condenser 5 flows through the adsorption tank 6 and then refluxes into the reaction distillation tower 4 through a reflux pump, with a reflux ratio of 2.5. The adsorption tank 6 is filled with 5A molecular sieve, which can effectively adsorb a small amount of water and other light component impurities in the reflux oil phase; the water phase in the condenser 5 is discharged from the reaction system through a pump. Although a trace amount of ethyl acetate and unreacted ethanol will inevitably dissolve in the water phase, most of the water will first condense into the water phase for extraction, thereby removing the water generated by the reaction in the tower and the waste solvent and the water entrained by the evaporation and vaporization of the waste liquid feed, thereby promoting the forward reaction; when the reflux reaction distillation is 2h, sampling and analysis are performed at the top of the reaction distillation tower 4, and the acetic acid conversion rate is determined to be 74.6%.

[0032] S3. After the reaction distillation tower 4 continues the reflux catalytic reaction for a period of time, when the ethyl acetate concentration in the gas phase of the partial condenser 5 reaches 94% by mass or more, the gas phase is cooled into liquid by a cooler and then enters a washing tank 7, wherein the washing tank 7 contains a saturated sodium carbonate solution for washing away trace acetic acid and a small amount of ethanol and water in the product. The crude ethyl acetate solution obtained by washing away trace impurities still contains a small amount of water, and then enters the extractive distillation tower 8 from the 15th plate for purification. The total number of plates of the extractive distillation tower 8 is 28, and the feed position of the extractant ethylene glycol is the 9th plate. The fraction temperature at the top of the tower is controlled at 79° C. 99.8% high-purity ethyl acetate can be obtained from the top of the extractive distillation tower 8, and the ethylene glycol extractant in the bottom of the extractive distillation tower 8 can be recycled after being treated by the extractant regeneration tower 9.

[0033] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Based on the present invention and the above description, relevant personnel can make various changes and modifications without departing from the technical idea of ​​the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A system for synthesizing high-purity ethyl acetate using waste liquid, characterized in that: It comprises a first grid tank (1), a second grid tank (2), an evaporation tank (3), a reaction distillation tower (4), a partial condenser (5), an adsorption tank (6), a first cooler (11), a washing tank (7), an extraction distillation tower (8) and a second cooler (12); The first grid pool (1) is provided with a waste solvent ethanol feed pipeline (101), the second grid pool (2) is provided with an acetic acid waste liquid feed pipeline (201), the discharge pipeline of the first grid pool (1) and the discharge pipeline of the second grid pool (2) are combined and connected to the feed port of the evaporator (3), the vaporized material discharge port (301) at the top of the evaporator (3) is connected to the lower feed port of the reaction distillation tower (4) through a pipeline, and the bottom of the evaporator (3) is provided with a heavy component impurity discharge port (302); the middle of the reaction distillation tower (4) is provided with an ethanol liquid feed pipeline (401), the top discharge port of the reaction distillation tower (4) is connected to the feed port of the partial condenser (5) through a pipeline; the oil phase discharge port (501) of the partial condenser (5) is connected to the reflux port (402) of the reaction distillation tower (4) through a pipeline; A water phase discharge port (502) is also provided at the bottom of the dephlegmator (5), a gas phase discharge port (503) at the top of the dephlegmator (5) is connected to the feed port of the first cooler (11) via a pipeline, the discharge port of the first cooler (11) is connected to the feed port of the washing tank (7) via a pipeline, the discharge port of the washing tank (7) is connected to the feed port in the middle of the extractive distillation tower (8) via a pipeline, an extractant feed pipeline (801) is provided at the top of the extractive distillation tower (8), a tower side discharge port of the extractive distillation tower (8) is connected to the feed port of the second cooler (12) via a pipeline, and an ethyl acetate discharge pipeline (1201) is provided on the second cooler (12).

2. A system for synthesizing high-purity ethyl acetate using waste liquid according to claim 1, characterized in that: An adsorption tank (6) is also provided on the connecting pipeline between the oil phase discharge port (501) of the dephlegmator (5) and the reflux port (402) of the reaction distillation tower (4); the oil phase discharge port (501) of the dephlegmator (5) is connected to the feed port of the adsorption tank (6) through the pipeline, and the discharge port of the adsorption tank (6) is connected to the reflux port (402) of the reaction distillation tower (4) through the pipeline.

3. A system for synthesizing high-purity ethyl acetate using waste liquid according to claim 1 or 2, characterized in that: The extractant regeneration tower (9) and the third cooler (13) are also included. The lower discharge port of the extractant distillation tower (8) is connected to the feed port of the extractant regeneration tower (9) through a pipeline. The discharge circulation port (901) of the extractant regeneration tower (9) is connected to the extractant feed pipeline (801) of the extractant distillation tower (8) through a pipeline. The tower side discharge port of the extractant regeneration tower (9) is connected to the feed port of the third cooler (13) through a pipeline. The third cooler (13) is provided with a wastewater discharge pipeline (1301).

4. A system for synthesizing high-purity ethyl acetate using waste liquid according to claim 1 or 2, characterized in that: The reaction distillation tower (4) is provided with 42 plates in total, the lower feed port of the reaction distillation tower (4) is located at the 35th plate of the reaction distillation tower (4), and the end of the ethanol liquid feed pipeline (401) is located at the 16th plate of the reaction distillation tower (4); the extractive distillation tower (8) is provided with 28 plates in total, the feed port of the extractive distillation tower (8) is located at the 15th plate of the extractive distillation tower (8), and the end of the extractant feed pipeline (801) is located at the 9th plate of the extractive distillation tower (8).

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