A natural ethyl hexanoate automatic continuous esterification device and a continuous esterification method

Abstract

This invention relates to the field of ethyl hexanoate processing technology, specifically to an automated continuous esterification equipment and method for natural ethyl hexanoate. It includes a reaction vessel, with a distillation column at the top. A primary condenser is connected to the top of the distillation column. The lower shell-side outlet of the primary condenser is connected to two parallel flow control lines. One flow control line connects to the upper end of the distillation column via a return pipe, and the other flow control line connects to a product recovery tank. The upper shell-side outlet of the primary condenser connects to a secondary condenser, and the shell-side outlet of the secondary condenser connects to a buffer tank, which is connected to a vacuum pump. A gas phase anti-impact structure is provided at the connection between the reaction vessel and the distillation column. This invention effectively improves the conversion rate and esterification quality of the ester through continuous esterification. The gas phase anti-impact structure effectively reduces the direct impact of the gas phase on the distillation column wall, significantly improving the gas phase control effect and the adaptability to the distillation process.

Description

Technical Field

[0001] This invention relates to the field of ethyl hexanoate processing technology, specifically to an automated continuous esterification equipment and method for natural ethyl hexanoate. Background Technology

[0002] Ethyl hexanoate is an important food additive and flavoring ingredient, widely used in the food, wine, and beverage industries. Natural ethyl hexanoate, in particular, retains the physicochemical properties and pure aroma of its natural counterpart, making it more suitable for the food and flavoring industries' high-end demand for green and natural additives, and thus has broad market prospects. The industrial synthesis of natural ethyl hexanoate mainly relies on the reversible esterification reaction of natural hexanoic acid with fermented ethanol, with the reaction equation: hexanoic acid + ethanol ⇌ ethyl hexanoate + water. This reaction requires a catalyst and is subject to reaction equilibrium. If the reaction products (ethyl hexanoate and water) cannot be removed in time, the reaction tends to reach equilibrium quickly, leading to low raw material conversion rates and increased catalyst usage.

[0003] Most current equipment is only suitable for single-feed, atmospheric-pressure, batch esterification. This method typically results in the use of large amounts of catalyst, generating significant waste liquid and increasing the difficulty and cost of waste liquid treatment. It also suffers from poor water separation, severe mixing of distillate materials, low esterification rate, numerous derivatives, poor flavor, increased labor intensity, and certain safety risks. Such equipment is fundamentally incapable of effectively and safely completing or achieving the desired esterification process and effect.

[0004] Furthermore, the current esterification equipment has a straight pipe connection between the reactor and the distillation column. The rising gas phase in the reactor carries a small amount of liquid droplets, causing the gas phase to be unable to disperse evenly and easily impact the distillation column wall, resulting in severe mist entrainment. The liquid droplets are carried into the rectification section of the distillation column, mixing with the gaseous products, reducing the rectification and separation efficiency, and consequently leading to decreased product purity and increased raw material loss.

[0005] In the prior art, patent document CN211099072U discloses an esterification reactor, including an esterification reactor body, with a gas distributor located between the esterification tower and the esterification reactor body to circumvent both. This structure, with a gas distributor between the esterification tower and the esterification reactor, can only achieve simple gas phase dispersion. It cannot prevent high-speed gas from directly impacting the tower wall, nor can it effectively intercept liquid droplets entrained in the gas phase; the problem of droplet entrainment remains fundamentally unresolved. Summary of the Invention

[0006] This invention provides an automated continuous esterification equipment and method for natural ethyl hexanoate, to solve the technical problems in the prior art where esterification equipment is not easy to continuously esterify, but the gas phase dispersion between the reaction vessel and the distillation column is uneven, easily impacting the column wall and causing mist entrainment, and the distillation efficiency is low.

[0007] To address the above problems, the present invention provides an automated continuous esterification equipment and method for natural ethyl hexanoate, employing the following technical solution: An automated continuous esterification device for natural ethyl hexanoate includes a reactor. A distillation column is connected to the top of the reactor. A primary condenser is connected to the top of the distillation column. The lower shell-side outlet of the primary condenser is connected to two parallel flow control lines. One flow control line is connected to the upper end of the distillation column via a return pipe, and the other flow control line is connected to a product recovery tank. A high-level conveying mechanism is connected to one side of the reactor. The upper shell-side outlet of the primary condenser is connected to a secondary condenser via a vacuum pipe. The shell-side outlet of the secondary condenser is connected to a buffer tank, which is connected to a vacuum pump.

[0008] The connection between the reactor and the distillation column is provided with a detachable gas phase anti-rush structure. The gas phase anti-rush structure includes a flow-limiting pipe and a dispersion guide part provided in the flow-limiting pipe. The end of the dispersion guide part opposite to the reactor is provided with an arc-shaped guide part. Multiple flow equalization channels are formed between the dispersion guide part and the flow-limiting pipe.

[0009] By adopting the above technical solution, continuous esterification and extraction can effectively and significantly reduce the amount of catalyst used and waste liquid generated. This effectively improves the ester conversion rate and esterification quality. Specifically, the gas phase anti-impact structure at the connection between the reactor and the distillation column effectively reduces the direct impact of rising gas from the reactor on the distillation column wall, preventing liquid mist from being entrained into the rectification section, while maintaining smooth gas flow.

[0010] Specifically, the original unidirectional direct-blowing gas flow is dispersed into multiple uniform gas flows through the equalization gas channel, allowing the gas to enter the rectification section of the distillation column at a uniform speed along the equalization gas channel. This ensures that the gas phase is in full and uniform contact with the packing and liquid phase in the rectification section, significantly improving the gas-liquid mass transfer efficiency and further enhancing the rectification and separation effect.

[0011] Furthermore, the dispersing guide section has a frustum-shaped structure, and the upper bottom surface of the frustum-shaped structure is opposite to the reaction vessel. The sides of the frustum-shaped structure are all concave arc-shaped guide surfaces.

[0012] Using the above technical solution, the concave arc-shaped guide surface forms a flanged structure. If a small amount of liquid droplets are entrained in the rising gas phase from the reactor, upon contact with the concave arc-shaped guide surface, the droplets will rapidly converge to the edge of the guide surface under the liquid-gathering effect of the curved surface. The naturally formed flanged structure of the guide surface will act as a barrier and limiter for the converging liquid phase, preventing the liquid phase from flowing upward along the edge of the guide surface and guiding the liquid phase to quickly drip back into the reactor along the flanged structure. In addition, the flanged structure of the concave arc-shaped guide surface performs secondary interception and rapid drainage of the small amount of entrained droplets, completely preventing liquid impurities from entering the rectification section of the distillation column and ensuring the separation efficiency of the rectification section.

[0013] Furthermore, the arc-shaped guide section has a downwardly convex spherical crown-shaped curved surface, and a resistance step is formed between the arc-shaped guide section and the upper bottom surface of the frustum-shaped structure.

[0014] By adopting the above technical solution, the spherical crown-shaped guide section is seamlessly connected to the frustum-shaped structure to form an integral dispersion guide front end, combined with the annular pressure-bearing structure of the resistance step. The overall mechanical strength is greatly improved, and it can effectively resist the inward squeezing force brought by the negative pressure inside the tower under vacuum decompression conditions. In addition, the resistance step forms a pre-buffered flow equalization, which, together with the subsequent frustum-shaped concave arc guide surface and flow equalization channel, forms a complete gas phase anti-impact dispersion system. Compared with a single guide structure, this achieves more thorough anti-fog entrainment, higher gas phase flow uniformity, and lower flow channel resistance.

[0015] Furthermore, the lower surface of the frustum-shaped structure is opposite to the distillation column, and each vertex of the lower surface of the frustum-shaped structure is welded to the inner wall of the flow-limiting pipe. The flow equalization channel is formed between two adjacent vertices of the lower surface of the frustum-shaped structure.

[0016] Furthermore, the high-level material conveying mechanism includes a high-level material tank, which is connected to the reactor via a discharge pipe, and the discharge pipe is equipped with a flow meter and a flow control valve.

[0017] Furthermore, a separator is connected to the lower end of the flow control pipeline that is connected to the product recycling tank. The upper liquid of the separator flows to the product recycling tank and the lower water flows to the water storage tank.

[0018] The pipeline connecting the separator and the product recovery tank has a branch line that connects to the reactor.

[0019] Furthermore, the pipeline connecting the secondary condenser and the buffer tank is provided with a branch line that connects to the product recovery tank.

[0020] The continuous esterification method of the above-mentioned automated continuous esterification equipment for natural ethyl hexanoate includes the following steps: First, add an appropriate amount of the raw materials and catalyst mixed according to the acid-alcohol ratio into the reactor as the base material. Then, slowly turn on the steam to raise the temperature, and at the same time start the vacuum pump and stir. When material distills out of the separator, determine whether to add raw materials to the high-level tank according to the state of the material in the separator.

[0021] If the material is in a turbid and unclear state, the material inside the vessel should be fed into the reactor at an appropriate flow rate to continue esterification.

[0022] If the raw material distilled from the separator reaches a state where the water and ester stratification interface is clear, the high-level conveying mechanism is turned on, and the high-level material is fed into the reactor from the bottom through the flow meter at an appropriate flow rate. At this time, the normal continuous esterification process begins.

[0023] Furthermore, during the continuous esterification process, the ratio of the two flow control pipelines is adjusted to 1:1, and the negative pressure is adjusted to 0.065 to 0.07 MPa to implement negative pressure esterification distillation.

[0024] Furthermore, the temperature of the reactor is 120-125℃.

[0025] The beneficial effects of the automated continuous esterification equipment and method for natural ethyl hexanoate provided by this invention are: This invention, through continuous esterification and extraction, effectively reduces catalyst usage and waste liquid generation, significantly improving ester conversion rate and esterification quality. Furthermore, the seamless connection between the spherical cap-shaped guide section and the frustum-shaped structure, combined with the naturally formed resistance step between them, achieves dual optimization of structural mechanical properties and gas-phase anti-impact dispersion function. It is suitable for the vacuum decompression core operating conditions of natural ethyl hexanoate esterification equipment and, together with the subsequent frustum-shaped concave arc guide surface and flow equalization channel, forms a complete gas-phase control system. Compared to traditional single guide structures, it significantly improves structural stability, gas-phase control effect, and adaptability to distillation processes.

[0026] In this invention, the pre-buffering and flow equalization effect formed by the resistance steps, in conjunction with the secondary dispersion of the subsequent frustum-shaped concave arc-shaped guide surface and the precise flow distribution depth of the flow equalization channel, constructs a multi-stage progressive complete gas phase anti-impact dispersion system. Compared with a single guide structure, this significantly improves the control effect on the rising gas phase. First, it more thoroughly prevents mist entrainment, intercepting liquid droplets entrained in the gas phase at the source and guiding them back to the reactor, preventing liquid impurities from entering the rectification section. Second, it achieves higher gas phase uniformity, transforming the originally unidirectional direct-blowing gas phase into multiple streams of gas with uniform velocity and consistent direction after multi-stage buffering and dispersion. Third, it reduces flow channel resistance, employing a smooth curved surface and localized low-resistance design throughout, without additional resistance-increasing structures, thus not increasing the total pressure drop of the gas phase flow and fully meeting the low-pressure-drop process requirements of vacuum reduced-pressure distillation. Attached Figure Description

[0027] The above and other objects, features, and advantages of exemplary embodiments of the present invention will become readily apparent upon reading the following detailed description with reference to the accompanying drawings. In the drawings, several embodiments of the invention are illustrated by way of example and not limitation, and like or corresponding reference numerals denote like or corresponding parts, wherein: Figure 1 This is an overall schematic diagram of the automated continuous esterification equipment for natural ethyl hexanoate of the present invention; Figure 2 This is a schematic diagram of the vapor phase anti-impact structure in this invention; Figure 3 This is a top view of the vapor phase anti-impact structure in this invention; Figure 4 This is a front cross-sectional view of the vapor phase anti-impact structure in this invention.

[0028] Explanation of reference numerals in the attached figures: 1. Reactor; 2. Distillation column; 3. Primary condenser; 31. Flow control pipeline; 32. Product recovery tank; 4. High-level conveying mechanism; 41. High-level material tank; 5. Secondary condenser; 6. Buffer tank; 7. Gas phase anti-impact structure; 71. Flow limiting pipeline; 72. Dispersion guide section; 721. Guide surface; 722. Resistance step; 73. Arc-shaped guide section; 74. Flow equalization channel; 8. Separator; 9. Water storage tank. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Those skilled in the art should understand that the embodiments described below are only some, not all, of the embodiments disclosed. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0030] The number of any elements in the accompanying drawings is for illustrative purposes only and not as a limitation, and any naming is for distinction only and has no limiting meaning.

[0031] The principles and spirit of the present invention will be explained in detail below with reference to several representative embodiments.

[0032] An embodiment of an automated continuous esterification device and method for natural ethyl hexanoate provided by the present invention: like Figures 1 to 4 As shown, An automated continuous esterification device for natural ethyl hexanoate includes a reactor 1. A distillation column 2 is connected to the top of the reactor 1. A primary condenser 3 is connected to the top of the distillation column 2. Two parallel flow control lines 31 are connected to the lower outlet of the shell side of the primary condenser 3. One flow control line 31 is connected to the upper end of the distillation column 2 through a return pipe 32, and the other flow control line 31 is connected to a product recovery tank 32. A high-level conveying mechanism 4 is connected to one side of the reactor 1.

[0033] The high-level conveying mechanism 4 includes a high-level material tank 41, which is connected to the reactor 1 through a discharge pipe. The discharge pipe is equipped with a flow meter and a flow control valve.

[0034] The high-level material tank gravity feeding, combined with flow meters and flow control valves, not only achieves continuous, stable, and low-energy supply of raw materials, but also ensures the dynamic matching of feed rate, esterification rate, and extraction rate through precise flow control, thus guaranteeing the continuous esterification process from the material level.

[0035] In this embodiment, the upper outlet end of the shell side of the first-stage condenser 3 is connected to the second-stage condenser 5 through a vacuum tube 33, the shell side outlet of the second-stage condenser 5 is connected to a buffer tank 6, and the buffer tank 6 is connected to a vacuum pump.

[0036] A separator 8 is connected to the lower end of the flow control pipeline 31 that is connected to the product recycling tank 32. The upper liquid of the separator 8 flows to the product recycling tank 32 and the lower water flows to the water storage tank 9.

[0037] The pipeline connecting the separator 8 and the product recovery tank 32 is provided with a branch that connects to the reactor 1.

[0038] Among them, the pipeline connecting the secondary condenser 5 and the buffer tank 6 is provided with a branch line that connects to the product recovery tank 32.

[0039] The separator 8 refluxes turbid materials back to the reactor 1, and recovers light components from each branch, achieving full reuse of unreacted raw materials and trace products, reducing the raw material loss rate to below 5%. Simultaneously, the reduction in catalyst usage further lowers the overall raw material cost, resulting in a reduction of over 40% in overall production and operating costs.

[0040] In this embodiment, a detachable gas phase anti-rush structure 7 is provided at the pipe connection between the reactor 1 and the distillation column 2. The gas phase anti-rush structure 7 includes a flow-limiting pipe 71 and a dispersion guide 72 provided in the flow-limiting pipe 71. An arc-shaped guide 73 is provided at the end of the dispersion guide 72 opposite to the reactor 1. Multiple flow equalization channels 74 are formed between the dispersion guide 72 and the flow-limiting pipe 71.

[0041] Specifically, both ends of the flow-limiting pipe 71 are equipped with flanges for external connection.

[0042] Among them, the gas phase anti-impact structure at the pipe connection between the reactor 1 and the distillation column 2 can effectively reduce the direct impact of the rising gas phase in the reactor 1 on the wall of the distillation column 2, prevent liquid phase mist from being entrained into the rectification section, and maintain the smooth flow of the gas phase.

[0043] Specifically, the original unidirectional direct-blowing gas flow is dispersed into multiple uniform gas flows through the equalization gas channel, allowing the gas to enter the rectification section of the distillation column at a uniform speed along the equalization gas channel. This ensures that the gas phase is in full and uniform contact with the packing and liquid phase in the rectification section, significantly improving the gas-liquid mass transfer efficiency and further enhancing the rectification and separation effect.

[0044] In this embodiment, the dispersing and guiding section 72 has a frustum-shaped structure, and the upper bottom surface of the frustum-shaped structure is opposite to the reactor 1. The sides of the frustum-shaped structure are all concave arc-shaped guiding surfaces 721.

[0045] The bottom surface of the frustum-shaped structure is opposite to the distillation column 2, and each vertex of the bottom surface of the frustum-shaped structure is welded to the inner wall of the flow-limiting pipe 71. The flow equalization channel 74 is formed between two adjacent vertices of the bottom surface of the frustum-shaped structure.

[0046] The concave arc-shaped guide surface 721 forms a flanged structure. If a small amount of liquid droplets are entrained in the rising gas phase from reactor 1, upon contact with the concave arc-shaped guide surface 721, the droplets will rapidly converge to the edge of the guide surface due to the liquid-gathering effect of the curved surface. The naturally formed flanged structure of the guide surface 721 acts as a barrier and limiter for the converging liquid phase, preventing it from flowing upwards along the edge of the guide surface and guiding it to quickly drip back into reactor 1 along the flanged structure. In addition, the flanged structure of the concave arc-shaped guide surface 721 performs secondary interception and rapid drainage of any entrained droplets, completely preventing liquid impurities from entering the rectification section of distillation column 2 and ensuring the separation efficiency of the rectification section.

[0047] Among them, the arc-shaped guide section 73 has a downwardly protruding spherical crown-shaped curved surface, and a resistance step 722 is formed between the arc-shaped guide section 73 and the upper bottom surface of the frustum-shaped structure.

[0048] The spherical crown-shaped guide section is seamlessly connected to the frustum-shaped structure, forming an integral dispersion guide front end. Combined with the annular pressure-bearing structure of the resistance step 722, the overall mechanical strength is greatly improved, effectively resisting the inward squeezing force brought by the negative pressure inside the tower under vacuum decompression conditions. In addition, the resistance step 722 forms a pre-buffered flow equalization, which, together with the subsequent frustum-shaped concave arc guide surface and the flow equalization channel 74, forms a complete gas phase anti-impact dispersion system. Compared with a single guide structure, this achieves more thorough anti-fog entrainment, higher gas phase uniformity, and lower flow channel resistance.

[0049] In this embodiment, the continuous esterification method of the automated continuous esterification equipment for natural ethyl hexanoate includes the following steps: First, an appropriate amount of raw materials and catalyst mixed according to the acid-alcohol ratio are added to reactor 1 as the base material. Then, the steam is slowly turned on to raise the temperature, while the vacuum pump and stirring are started at the same time. When material is distilled out of separator 8, it is determined whether to add raw materials to the high-level tank according to the state of the material in separator 8.

[0050] If the material is in a turbid and unclear state, the material in the vessel should be fed into reactor 1 at an appropriate flow rate to continue esterification.

[0051] If the raw material distilled from separator 8 reaches a state where the water and ester stratification interface is clear, the high-level conveying mechanism 4 is turned on, and the high-level material is fed into reactor 1 from the bottom through the flow meter at an appropriate flow rate. At this time, the normal continuous esterification process begins.

[0052] Specifically, during the continuous esterification process, the ratio of the two flow control lines 31 is adjusted to 1:1, and the negative pressure is adjusted to 0.065 to 0.07 MPa to implement negative pressure esterification distillation.

[0053] The temperature of reactor 1 is 120-125℃.

[0054] Based on the above description in this specification, those skilled in the art will also understand that the following terms, such as "upper," "lower," "front," "rear," "left," "right," "width," "horizontal," "top," "bottom," "inner," and "outer," which indicate orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings of this specification. They are only for the purpose of facilitating the explanation of the present invention and simplifying the description, and do not explicitly or implicitly suggest that the device or element involved must have the specific orientation, or be constructed and operated in a specific orientation. Therefore, the above-mentioned orientation or positional relationship terms should not be understood or interpreted as limitations on the present invention.

[0055] In addition, in the description of this specification, "multiple" means at least two, such as two, three or more, etc., unless otherwise expressly and specifically defined.

Claims

1. An automated continuous esterification device for natural ethyl hexanoate, comprising a reactor (1), wherein a distillation column (2) is connected to the top of the reactor (1), and a primary condenser (3) is connected to the top of the distillation column (2). Two parallel flow control lines (31) are connected to the lower outlet of the shell side of the primary condenser (3), one of which is connected to the upper end of the distillation column (2) via a return pipe (32), and the other is connected to a product recovery tank (32). The device is characterized in that... The reactor (1) is connected to a high-level conveying mechanism (4) on one side. The upper outlet end of the shell side of the first-stage condenser (3) is connected to the second-stage condenser (5) through a vacuum tube (33). The shell side outlet of the second-stage condenser (5) is connected to a buffer tank (6). The buffer tank (6) is connected to a vacuum pump. The connection between the reactor (1) and the distillation column (2) is provided with a detachable gas phase anti-rush structure (7). The gas phase anti-rush structure (7) includes a flow-limiting pipe (71) and a dispersion guide (72) provided in the flow-limiting pipe (71). The end of the dispersion guide (72) opposite to the reactor (1) is provided with an arc-shaped guide (73). Multiple flow equalization channels (74) are formed between the dispersion guide (72) and the flow-limiting pipe (71).

2. The automated continuous esterification equipment for natural ethyl hexanoate according to claim 1, characterized in that, The dispersion guide section (72) has a frustum-shaped structure, and the upper bottom surface of the frustum-shaped structure is opposite to the reactor (1); The sides of the frustum-shaped structure are all concave arc-shaped flow guide surfaces (721).

3. The automated continuous esterification equipment for natural ethyl hexanoate according to claim 2, characterized in that, The arc-shaped guide section (73) has a downwardly protruding spherical crown-shaped curved surface, and a resistance step (722) is formed between the arc-shaped guide section (73) and the upper bottom surface of the frustum-shaped structure.

4. The automated continuous esterification equipment for natural ethyl hexanoate according to claim 2, characterized in that, The bottom surface of the frustum-shaped structure is opposite to the distillation column (2), and each vertex of the bottom surface of the frustum-shaped structure is welded to the inner wall of the flow-limiting pipe (71). The flow equalization channel (74) is formed between two adjacent vertices of the bottom surface of the frustum-shaped structure.

5. The automated continuous esterification equipment for natural ethyl hexanoate according to claim 1, characterized in that, The high-level conveying mechanism (4) includes a high-level material tank (41), which is connected to the reactor (1) through a discharge pipe. The discharge pipe is equipped with a flow meter and a flow control valve.

6. The automated continuous esterification equipment for natural ethyl hexanoate according to claim 1, characterized in that, A separator (8) is connected to the lower end of the flow control pipeline (31) connected to the product recycling tank (32). The upper liquid of the separator (8) flows to the product recycling tank (32) and the lower water flows to the water storage tank (9). The pipeline connecting the separator (8) and the product recovery tank (32) is provided with a branch that connects to the reactor (1).

7. The automated continuous esterification equipment for natural ethyl hexanoate according to claim 1, characterized in that, The pipeline connecting the secondary condenser (5) and the buffer tank (6) is provided with a branch line that connects to the product recovery tank (32).

8. A continuous esterification method for ethyl hexanoate using an automated continuous esterification apparatus as described in any one of claims 1-7, characterized in that, Includes the following steps: First, the raw materials and catalyst mixed according to the acid-alcohol ratio are added to the reactor (1) as the base material. Then, the steam is slowly turned on to raise the temperature. At the same time, the vacuum pump and stirring are started. When the material distills out of the separator (8), it is determined whether to add raw materials to the high-level tank according to the state of the material in the separator (8). If the material is in a turbid and unclear state, the material in the vessel will be flowed into the reactor (1) at an appropriate flow rate to continue esterification; If the raw material distilled from the separator (8) reaches a clear water-ester stratification interface, the high-level conveying mechanism (4) is turned on, and the high-level material is fed into the reactor (1) from the bottom of the reactor (1) through the flow meter at an appropriate flow rate. At this time, the normal continuous esterification process begins.

9. The continuous esterification method of the automated continuous esterification equipment for natural ethyl hexanoate according to claim 8, characterized in that, During continuous esterification, the ratio of the two flow control lines (31) is adjusted to 1:1, and the negative pressure is adjusted to 0.065 to 0.07 MPa to carry out esterification distillation with reduced negative pressure.

10. The continuous esterification method of the automated continuous esterification equipment for natural ethyl hexanoate according to claim 8, characterized in that, The temperature of the reactor (1) is 120-125℃.

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