System for synthesizing ethyl acetate

Abstract

A system for synthesizing ethyl acetate comprises a reduced pressure esterification tower, a phase splitter, a dehydrating tower, a refining tower, a product storage tank and a recovery tower, the reduced-pressure esterification tower is connected with the phase splitter through a pipeline; the bottom of the phase splitter is connected with the recovery tower through a pipeline, and the upper part is connected with the ester phase tank through a pipeline; the ester phase tank is connected with the decompression esterification tower and the dehydration tower through pipelines; the lower part of the dehydrating tower is connected with the recovery tower through a pipeline, and the upper part is connected with the refining tower through a refining feeding tank; the refining tower is connected with the product storage tank through a pipeline. The esterification tower disclosed by the utility model adopts a decompression reaction mode, so that the reaction temperature is greatly reduced, the steam consumption is reduced, the steam unit consumption of the esterification tower in the traditional process is 1.0 t / t, the steam unit consumption of the decompression esterification tower is 0.7 t / t, and the purposes of reducing the energy consumption and the cost are fundamentally realized.

Description

Technical Field

[0001] The utility model belongs to the field of chemical equipment, in particular to a system for synthesizing ethyl acetate. Background Art

[0002] Ethyl acetate is an important organic compound and a widely used fine chemical product. It has excellent solubility and quick drying properties. It is widely used as an organic solvent in coatings and inks, a cleaning agent in the textile industry, and a flavor extractant for special modified alcohols in the food industry. It is also used as an extractant in pharmaceutical processes and organic acids. Ethyl acetate is also a raw material for the manufacture of dyes, drugs and spices. It is an important organic chemical raw material and an excellent industrial solvent.

[0003] The traditional preparation methods of ethyl acetate include: direct esterification of ethanol with acetic acid, acetaldehyde condensation, ethanol dehydrogenation, direct addition of ethylene and acetic acid, and catalytic distillation. Among them, direct esterification is the main process route for the domestic industrial production of ethyl acetate. Acetic acid and ethanol are used as raw materials and sulfuric acid is used as a catalyst to directly esterify ethyl acetate, which is then dehydrated and fractionated to obtain the finished product. The disadvantages of this process are as follows: (1) The oxidizing and strong dehydrating properties of concentrated sulfuric acid can easily lead to a series of side reactions, affecting the quality of the product; (2) The post-treatment of the reaction product requires alkaline neutralization and water washing, which is relatively complicated and difficult, and also produces a large amount of waste liquid, polluting the environment; (3) Inorganic strong acid catalysts usually cause equipment corrosion, and the equipment requirements are relatively strict, requiring a large investment amount.

[0004] For example, a Chinese invention patent (publication number CN105712873A) discloses a control method for synthesizing ethyl acetate by esterification, which includes the following steps: a. controlling the molar ratio of acetic acid to ethanol in the mixer to be 1:1, and conveying the uniformly stirred mixture to the esterification tower; b. setting sulfuric acid at the bottom of the esterification tower and only at the bottom of the esterification tower; c. heating the esterification reaction through the esterification reboiler to generate gaseous ethyl acetate and water; d. the gaseous ethyl acetate and water enter the esterification phase separator through the esterification condenser and the esterification cooler to obtain ethyl acetate; the method simplifies the existing ethyl acetate synthesis system, controls the ratio of acetic acid and ethanol and the catalyst sulfuric acid and the reaction temperature, and solves the technical problem of low ethyl acetate generation rate in the traditional process. At the same time, it simplifies the subsequent separation system, thereby reducing steam consumption by 50% and improving the product generation efficiency. However, a large amount of gaseous condensation heat in the process is not fully utilized, the heat loss is large, and the investment cost is high.

[0005] For another example, the Chinese invention patent (publication number CN115108910A) discloses a synthesis and heat coupling process of ethyl acetate, which reacts excess acetic acid with ethanol, pumps the reaction product into a mixing tank, mixes it evenly with tetrahydrofuran with water, pumps the resulting mixture into a distillation tower, controls the temperature and pressure of the distillation tower, extracts tetrahydrofuran and water from the top vapor phase, extracts ethyl acetate from the middle of the distillation tower, and extracts excess acetic acid and sulfuric acid catalyst from the bottom of the distillation tower and reuses them in the esterification tower to participate in the reaction; and the ethyl acetate product extracted from the top vapor phase of the distillation tower and the middle of the distillation tower is heat exchanged with the reaction raw materials through a heat exchanger. This technology uses a heat coupling process and heat exchange between the product and the reaction raw materials, which reduces the supply of heat and reduces costs. However, the product obtained by this process has a large amount of water-carrying agent, which also increases the input of raw materials, and also increases the equipment investment of the heat coupler, and the purity of the ethyl acetate product finally obtained is not high, and the ethanol content is relatively high.

[0006] The unit steam consumption of the conventional industrial process for producing ethyl acetate products is about 1.5-2t / t, and the unit steam consumption of the esterification tower is 1.0t / t. The esterification tower consumes too much steam and has a high cost, which brings great economic pressure to the enterprise. Summary of the invention

[0007] The utility model aims at the technical defects existing in the background technology and provides a system for synthesizing ethyl acetate.

[0008] The technical solution adopted by the utility model is: a system for synthesizing ethyl acetate, comprising a vacuum esterification tower, a phase separator, a dehydration tower, a refining tower, a product storage tank and a recovery tower;

[0009] The vacuum esterification tower is connected to the phase separator through a pipeline; the bottom of the phase separator is connected to the recovery tower through a pipeline, and the upper part is connected to the ester phase tank through a pipeline; the ester phase tank is connected to the vacuum esterification tower and the dehydration tower through a pipeline; the lower part of the dehydration tower is connected to the recovery tower through a pipeline, and the upper part is connected to the refining tower through a pipeline via a refining feed tank; the refining tower is connected to the product storage tank through a pipeline.

[0010] As a preferred technical solution: metering pumps are respectively arranged on the pipelines connecting the ester phase tank with the vacuum esterification tower and the dehydration tower to control the split flow rate.

[0011] As a preferred technical solution: the reduced pressure esterification tower is connected to a vacuum pump.

[0012] As a preferred technical solution: the temperature of the kettle in the esterification tower is controlled to be 60-85°C; and the reaction pressure is controlled to be -0.05-0.07MPa.

[0013] As a preferred technical solution: the ratio of the flow rate at the top of the reflux vacuum esterification tower to the flow rate entering the dehydration tower is 0.5-1:1.

[0014] As a preferred technical solution: the kettle temperature in the recovery tower is 85-95°C, and the tower pressure is normal pressure; the kettle temperature in the dehydration tower is 75-85°C, and the tower pressure is normal pressure.

[0015] As a preferred technical solution: the temperature of the kettle in the refining tower is controlled to be 75-85°C, and the tower pressure is normal pressure.

[0016] Compared with the prior art, the utility model has the following advantages and beneficial effects: the esterification tower adopts a reduced pressure reaction mode, which greatly reduces the reaction temperature and reduces the steam consumption. The steam unit consumption of the traditional esterification tower is 1.0t / t, and the steam unit consumption of the reduced pressure esterification tower is 0.7t / t, which fundamentally achieves the purpose of reducing energy consumption and reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is the layout diagram of the reaction system in the utility model.

[0018] The following are marked in the figure:

[0019] 1 is a vacuum esterification tower, 2 is a phase separator, 2-1 is an ester phase tank, 3 is a dehydration tower, 4 is a refining tower, 4-1 is a refining feed tank, 5 is a product storage tank, 6 is a recovery tower, 7 is a first metering pump, and 8 is a second metering pump. DETAILED DESCRIPTION

[0020] The present invention is described in detail with reference to the following specific embodiments in conjunction with the accompanying drawings. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and a specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0021] The system for synthesizing ethyl acetate disclosed in the utility model comprises a vacuum esterification tower 1, a phase separator 2, a dehydration tower 3, a refining tower 4, a product storage tank 5 and a recovery tower 6. The vacuum esterification tower 1 is connected to the phase separator 2 through a pipeline; the bottom of the phase separator 2 is connected to the recovery tower 6 through a pipeline, the upper part of the phase separator 2 is connected to the ester phase tank 2-1 through a pipeline, and the ester phase tank 2-1 is respectively connected to the vacuum esterification tower 1 and the dehydration tower 3 through pipelines. The lower part of the dehydration tower 3 is connected to the recovery tower 6 through a pipeline, and the upper part of the dehydration tower 3 is connected to the refining tower 4 through a pipeline via a refining feed tank 4-1. The ester phase at the top of the dehydration tower 3 enters the refining feed tank 4-1 to be purified by the refining tower 4, and the water phase at the bottom of the dehydration tower 3 enters the recovery tower 6 for recycling. The refining tower 4 is connected to the product storage tank 5 through a pipeline.

[0022] As a preferred technical solution: metering pumps, namely the first metering pump 7 and the second metering pump 8, are respectively arranged on the pipelines connecting the ester phase tank with the vacuum esterification tower and the dehydration tower to control the split flow. The ratio of the top flow of the reflux vacuum esterification tower to the flow entering the dehydration tower is 0.5-1:1.

[0023] The reduced pressure esterification tower is connected to a vacuum pump to achieve vacuum treatment.

[0024] The specific process of synthesizing ethyl acetate using the above system is as follows:

[0025] 1. Excess acetic acid and ethanol are sent into a vacuum esterification tower after heat exchange through a metering pump and a heat exchanger, and an ionic liquid catalyst is added to prepare for the reaction.

[0026] 2. The vacuum esterification tower is evacuated, and the temperature of the kettle in the esterification tower is controlled to be 60-85°C; the reaction pressure in the esterification tower is controlled to be -0.05--0.07MPa. A large amount of ethyl acetate, water and trace ethanol are produced from the top of the vacuum esterification tower. The top materials are condensed and heat exchanged before entering the phase separator for separation.

[0027] 3. The lower aqueous phase material of the product in the phase separator enters the recovery tower to recover a small amount of ethyl acetate and water. The upper ester phase material of the product in the phase separator enters the ester phase tank again. A part of it is returned to the top of the vacuum esterification tower as reflux liquid through the metering pump for reflux, and the other part enters the dehydration tower to continue the aqueous phase separation. The ester phase at the top of the dehydration tower enters the refined feed tank again, and the aqueous phase at the bottom of the tower enters the recovery tower for recycling.

[0028] The reflux ratio of the ester phase tank is 0.5-1:1, that is, the ratio of the flow rate entering the top of the vacuum esterification tower to the flow rate entering the dehydration tower; the temperature of the kettle in the recovery tower is controlled at 85-95°C, and the tower pressure is normal pressure; the temperature of the kettle in the dehydration tower is controlled at 75-85°C, and the tower pressure is normal pressure.

[0029] 4. The crude ethyl acetate in the refining feed tank enters the refining tower for refining. The ethyl acetate produced from the top of the tower enters the product storage tank after condensation and heat exchange to obtain a product with higher purity.

[0030] In this step, the temperature of the kettle in the refining tower is controlled to be 75-85° C., and the tower pressure is normal pressure; the composition of the ethyl acetate product extracted from the top of the refining tower is: ethyl acetate ≥ 99.9%, ethanol < 0.1%, water < 0.01%, and acetic acid < 0.01%.

Claims

1. A system for synthesizing ethyl acetate, characterized in that: It includes vacuum esterification tower, phase separator, dehydration tower, refining tower, product storage tank and recovery tower; The vacuum esterification tower is connected to the phase separator through a pipeline; the bottom of the phase separator is connected to the recovery tower through a pipeline, and the upper part is connected to the ester phase tank through a pipeline; the ester phase tank is connected to the vacuum esterification tower and the dehydration tower through a pipeline; the lower part of the dehydration tower is connected to the recovery tower through a pipeline, and the upper part is connected to the refining tower through a pipeline via a refining feed tank; the refining tower is connected to the product storage tank through a pipeline.

2. The system for synthesizing ethyl acetate according to claim 1, characterized in that: Metering pumps are respectively arranged on the pipelines connecting the ester phase tank with the vacuum esterification tower and the dehydration tower to control the split flow rate.

3. The system for synthesizing ethyl acetate according to claim 1, characterized in that: The reduced pressure esterification tower is connected to a vacuum pump.

Images