A system and method for effectively promoting esterification reaction

Abstract

The present invention discloses a system and method for effectively promoting esterification reaction, including a first reaction kettle, a second reaction kettle, a dryer, a first heat exchanger, a second heat exchanger, a mixing tank, and a transfer pump. The method includes: (1) Butyric acid or methanol enters the second reaction kettle for heat exchange through the second heat exchanger and the first heat exchanger; (2) Glycerol or fatty acid is added to the first reaction kettle, and a catalyst and butyric acid or methanol are added to the mixing tank and dissolved and mixed; (3) The glycerol or fatty acid in the first reaction kettle is mixed with the water-containing butyric acid or methanol in the first heat exchanger and the catalyst in the mixing tank to carry out the first esterification reaction; (4) The glycerol tributyrate or methyl ester in the first reaction kettle is pumped into the second reaction kettle, and anhydrous butyric acid or anhydrous methanol is added through the first heat exchanger for mixing to carry out the second esterification reaction; (5) High-purity glycerol tributyrate or biodiesel is discharged from the second reaction kettle. The present invention adopts a two-stage or multi-stage reaction kettle for reaction, can continuously feed, continuously react, and continuously discharge materials, with low cost and high efficiency.

Description

Technical Field

[0001] The present invention relates to fatty acid esterification, such as the preparation of glycerol butyrate and biodiesel. Specifically, it relates to a system that can effectively promote the esterification reaction, and the present invention also relates to a method for effectively promoting the esterification reaction. Background Art

[0002] The reaction between fatty acids and hydroxyl groups is generally referred to as esterification. For example, the reaction between fatty acids and glycerol produces fatty acid glycerides, and the reaction between fatty acids and alcohol groups produces fatty acid methyl esters (commonly known as biodiesel), fatty acid ethyl esters, propyl esters, etc. During the esterification reaction, water is simultaneously produced. When the content of the generated water increases, along with the reversible reaction, that is, when the reaction reaches equilibrium, it not only affects the reaction efficiency but also affects the purity of the fatty esters. Therefore, how to improve the reaction efficiency and the purity of the fatty esters is the key to the esterification reaction.

[0003] Currently, the commonly used esterification method is to use a single reaction kettle. Under the action of a suitable catalyst, an excessive amount of hydroxyl substances, such as glycerol, methanol, etc., is added to the fatty acid to reduce the water concentration and improve the reaction efficiency. This method has the problem that an excessive amount of hydroxyl substances is added and needs to be refined again, resulting in an increase in production costs. At the same time, by increasing the temperature to evaporate the water generated in the reaction, the equilibrium is destroyed to promote the forward reaction. This method has the problems of high heat energy consumption and an increase in production costs. Moreover, using the production means of a single kettle has large investment, complex operation, heat energy waste, and an increase in production costs. However, both of these methods have the characteristics that biodiesel is a renewable energy source, has good environmental friendliness, and is biodegradable. Compared with traditional fossil diesel, due to the high oxygen content of biodiesel, it burns fully, and the emissions of toxic substances are low, releasing less particulate matter, carbon dioxide, sulfur oxides, hydrocarbons, soot, etc. Therefore, a worldwide upsurge in the research of biodiesel has been set off.

[0004] For example, in the production of tributyrin, using the direct esterification method, 2 times the excessive amount of butyric acid needs to be added to react with glycerol. At high temperature, the water is evaporated to promote the forward reaction, but at the same time, the water accompanying the butyric acid needs to be removed by rectification again, with low efficiency and high heat energy consumption.

[0005] For example, in the production of biodiesel using a large amount of waste cooking oil, the commonly used methods are the acid-base two-step catalysis method, the bioenzyme catalysis method, and the supercritical method. Among them, the acid-base two-step catalysis method mostly uses batch production, with large investment and high heat energy consumption due to gaseous methylation. For the bioenzyme catalysis method and the supercritical method, it is difficult to reduce the acid value of the crude methyl ester to below 5 mg KOH / g. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a system and a method that can effectively promote the esterification reaction, through which the reaction efficiency can be improved and the production cost can be reduced.

[0007] To solve the above technical problems, the technical solution adopted by the present invention is: a system for effectively promoting the esterification reaction, including a first reaction kettle, a second reaction kettle, a dryer, a first heat exchanger, a second heat exchanger, a mixing tank, and a transfer pump. The mixing tank is connected to the first reaction kettle through a pipeline. The first reaction kettle is connected to the second reaction kettle through a transfer pump. The second reaction kettle is connected to the first heat exchanger through a dryer. The first heat exchanger is also connected to the second reaction kettle through another pipeline. The first heat exchanger is connected to the first reaction kettle through a pipeline, the first heat exchanger is connected to the second heat exchanger through a pipeline, and the second heat exchanger is connected to the first reaction kettle through a pipeline. The catalyst input pipeline is connected to the mixing tank. The fatty acid or glycerol input pipeline is connected to the first reaction kettle. The butyric acid or methanol input pipeline is respectively connected to the mixing tank and the second heat exchanger. The second heat exchanger is also connected to the water-containing butyric acid or methanol output pipeline. The second reaction kettle and the first reaction kettle are connected through a transfer pump.

[0008] A method for effectively promoting the esterification reaction according to the present invention includes the following steps:

[0009] (1). Butyric acid or methanol enters the second reaction kettle through the second heat exchanger and the first heat exchanger, and exchanges heat between the liquid-phase butyric acid or methanol and the gas-phase butyric acid or methanol.

[0010] (2). Glycerol or fatty acid is added to the first reaction kettle, and a catalyst and butyric acid or a catalyst and methanol are added to the mixing tank and fully dissolved and mixed.

[0011] (3). The glycerol or fatty acid in the first reaction kettle is mixed with the water-containing butyric acid or methanol from the first heat exchanger and the catalyst from the mixing tank and reacts to carry out the first esterification reaction.

[0012] (4). The butyric acid glyceride or methyl ester in the first reaction kettle is pumped into the second reaction kettle through a transfer pump, and anhydrous butyric acid or anhydrous methanol is added through the first heat exchanger in the second reaction kettle and mixed and reacted to carry out the second esterification reaction.

[0013] (5). A small amount of water generated during the reaction in the second reaction kettle evaporates together with the butyric acid gas or methanol gas. The water in the mixed gas phase of butyric acid and water or the mixed gas phase of methanol and water is absorbed by the desiccant in the dryer to improve the purity of butyric acid or methanol. Then, it exchanges heat with the anhydrous butyric acid or anhydrous methanol passing through the first heat exchanger and then enters the first reaction kettle.

[0014] (6). A small amount of water generated during the reaction in the first reaction kettle evaporates together with the butyric acid or methanol gas, exchanges heat with the anhydrous butyric acid or anhydrous methanol passing through the second heat exchanger, and after condensation, the butyric acid or methanol is stored as water-containing butyric acid or water-containing methanol for standby or reused after rectification and dehydration.

[0015] (7). Stop the reaction and discharge high-purity tributyrin or biodiesel from the second reaction kettle.

[0016] In step (2), when producing glyceryl tributyrate, the catalyst is an acidic catalyst, and the addition amount of the catalyst is 0.1-0.5% of the weight of glycerol. The molar ratio of the addition amount of butyric acid to glycerol is 1.5-2:1. In steps (2) and (3), the reaction temperatures of reactor 1 and reactor 2 are both 150-180°C.

[0017] In step (2), when producing biodiesel, the catalyst is an acidic catalyst, and the addition amount of the catalyst is 0.1-0.3% of the weight of fat. The addition amount of methanol is 15-20% of the fatty acid. In steps (2) and (3), the reaction temperatures of reactor 1 and reactor 2 are both 80-95°C.

[0018] An effective esterification reaction promoting system and method designed by the present invention adopt the above technical solutions, and can carry out multi-stage reactions through two-stage or multi-stage reactors. The mixed gas of butyric acid or methanol and water is absorbed by a desiccant to remove the water therein, improving the purity and being beneficial to improving the reaction efficiency in the next step. The low-temperature liquid-phase butyric acid or methanol exchanges heat with the high-temperature butyric acid or methanol gas phase to save heat energy. The present invention can realize continuous production, thus realizing the functions of continuous feeding, continuous reaction, and continuous discharging. The preparation effects of glyceryl tributyrate and biodiesel are good, with low cost and high efficiency, effectively promoting the esterification reaction. Description of the Drawings

[0019] Figure 1 It shows a schematic structural diagram of an effective esterification reaction promoting system of the present invention. Detailed Embodiments

[0020] The following specifically describes an effective esterification reaction promoting system and method of the present invention with reference to the drawings.

[0021] An effective esterification reaction promoting system of the present invention, see Figure 1 (taking the preparation of biodiesel as an example), includes reactor 1, reactor 2, dryer 3, heat exchanger 1, heat exchanger 2, mixing tank 6, and transfer pump 7. Among them, the mixing tank 6 is connected to the reactor 1 through corresponding pipelines. The reactor 1 is connected to the reactor 2 through the transfer pump 7 by corresponding pipelines. The reactor 2 is connected to the heat exchanger 1 through the dryer 3 by corresponding pipelines. The heat exchanger 1 is also connected to the reactor 2 through other pipelines. The heat exchanger 1 is connected to the reactor 1 through corresponding pipelines. The heat exchanger 1 is connected to the heat exchanger 2 through corresponding pipelines. The heat exchanger 2 is connected to the reactor 1 through corresponding pipelines. The catalyst input pipeline is connected to the mixing tank 6. The glycerol (or fatty acid) input pipeline is connected to the reactor 1. The input pipelines of butyric acid (or methanol) are respectively connected to the mixing tank 6 and the heat exchanger 2. The heat exchanger 2 is also connected to the output pipeline of water-containing butyric acid (water-containing methanol).

[0022] Embodiment 1 of a method for effectively promoting esterification reaction of the present invention comprises the following steps:

[0023] (1) The butyric acid enters the reactor 2 after passing through the heat exchanger 2 and the heat exchanger 1, and the liquid phase butyric acid and the gas phase butyric acid are heat exchanged;

[0024] (2) Add glycerol to the reactor 1, add an acid catalyst and butyric acid to the mixing tank and fully dissolve and mix them. The amount of the acid catalyst added is 0.1% of the weight of the glycerol, and the molar ratio of the butyric acid added to the glycerol is 1.5:1;

[0025] (3) The glycerol in the reactor 1 is mixed with the aqueous butyric acid from the heat exchanger 1 and the catalyst from the mixing tank to react and perform the first esterification reaction; the reaction temperature of the reactor 1 is 150°C;

[0026] (4) The butyric acid glyceride in reactor one is pumped into reactor two through a delivery pump, and anhydrous butyric acid is added to reactor two through heat exchanger one for mixing and reaction to carry out a second esterification reaction. The reaction temperature of reactor two is 150°C;

[0027] (5) A small amount of water generated during the reaction in the reactor 2 evaporates together with the butyric acid gas, and the water in the mixed gas phase of butyric acid and water is absorbed by the desiccant in the dryer to improve the purity of the butyric acid. The butyric acid is then passed through the heat exchanger 1 for heat exchange with the anhydrous butyric acid that has passed through the heat exchanger 1, and then enters the reactor 1;

[0028] (6) A small amount of water generated during the reaction in reactor 1 evaporates together with the butyric acid gas, and exchanges heat with the anhydrous butyric acid passing through heat exchanger 2. After condensation, the butyric acid is output as aqueous butyric acid and stored for standby use or distilled and dehydrated for reuse;

[0029] (7) Stop the reaction and discharge high purity tributyrin from reactor 2.

[0030] Embodiment 2 of a method for effectively promoting esterification reaction of the present invention comprises the following steps:

[0031] (1) The butyric acid enters the reactor 2 after passing through the heat exchanger 2 and the heat exchanger 1, and the liquid phase butyric acid and the gas phase butyric acid are heat exchanged;

[0032] (2) Add glycerol to the reactor 1, add an acid catalyst and butyric acid to the mixing tank and fully dissolve and mix them. The amount of the acid catalyst added is 0.3% of the weight of the glycerol, and the molar ratio of the butyric acid added to the glycerol is 1.7:1;

[0033] (3) The glycerol in the reactor 1 is mixed with the aqueous butyric acid from the heat exchanger 1 and the catalyst from the mixing tank to react and perform the first esterification reaction; the reaction temperature of the reactor 1 is 165°C;

[0034] (4) The butyric acid glyceride in reactor one is pumped into reactor two through a delivery pump, and anhydrous butyric acid is added to reactor two through heat exchanger one for mixing and reaction to carry out a second esterification reaction. The reaction temperature of reactor two is 165°C;

[0035] (5) A small amount of water generated during the reaction in the reactor 2 evaporates together with the butyric acid gas, and the water in the mixed gas phase of butyric acid and water is absorbed by the desiccant in the dryer to improve the purity of the butyric acid. The butyric acid is then passed through the heat exchanger 1 for heat exchange with the anhydrous butyric acid that has passed through the heat exchanger 1, and then enters the reactor 1;

[0036] (6) A small amount of water generated during the reaction in reactor 1 evaporates together with the butyric acid gas, and exchanges heat with the anhydrous butyric acid passing through heat exchanger 2. After condensation, the butyric acid is output as aqueous butyric acid and stored for standby use or distilled and dehydrated for reuse;

[0037] (7) Stop the reaction and discharge high purity tributyrin from reactor 2.

[0038] Embodiment 3 of a method for effectively promoting esterification reaction of the present invention comprises the following steps:

[0039] (1) The butyric acid enters the reactor 2 after passing through the heat exchanger 2 and the heat exchanger 1, and the liquid phase butyric acid and the gas phase butyric acid are heat exchanged;

[0040] (2) Add glycerol to the reactor 1, add an acid catalyst and butyric acid to the mixing tank and fully dissolve and mix them. The amount of the acid catalyst added is 0.5% of the weight of the glycerol, and the molar ratio of the butyric acid added to the glycerol is 2:1;

[0041] (3) The glycerol in the reactor 1 is mixed with the aqueous butyric acid from the heat exchanger 1 and the catalyst from the mixing tank to react and perform the first esterification reaction; the reaction temperature of the reactor 1 is 180°C;

[0042] (4) The butyric acid glyceride in the reactor 1 is pumped into the reactor 2 through a delivery pump, and anhydrous butyric acid is added to the reactor 2 through a heat exchanger 1 for mixing and reaction to carry out a second esterification reaction. The reaction temperature of the reactor 2 is 180°C;

[0043] (5) A small amount of water generated during the reaction in the reactor 2 evaporates together with the butyric acid gas, and the water in the mixed gas phase of butyric acid and water is absorbed by the desiccant in the dryer to improve the purity of the butyric acid. The butyric acid is then passed through the heat exchanger 1 for heat exchange with the anhydrous butyric acid that has passed through the heat exchanger 1, and then enters the reactor 1;

[0044] (6) A small amount of water generated during the reaction in reactor 1 evaporates together with the butyric acid gas, and exchanges heat with the anhydrous butyric acid passing through heat exchanger 2. After condensation, the butyric acid is output as aqueous butyric acid and stored for standby use or distilled and dehydrated for reuse;

[0045] (7) Stop the reaction and discharge high purity tributyrin from reactor 2.

[0046] Embodiment 4 of a method for effectively promoting esterification reaction of the present invention comprises the following steps:

[0047] (1) Methanol enters reactor 2 after passing through heat exchanger 2 and heat exchanger 1, and heat is exchanged between liquid methanol and gaseous methanol;

[0048] (2) Add fatty acid to reactor 1, add acid catalyst and methanol to the mixing tank and fully dissolve and mix; the amount of catalyst added is 0.1% of the weight of the fat, and the amount of methanol added is 15% of the fatty acid;

[0049] (3) The fatty acid in the reactor 1 is mixed with the aqueous methanol from the heat exchanger 1 and the catalyst from the mixing tank to react and perform the first esterification reaction. The reaction temperature of the reactor 1 is 80°C.

[0050] (4) The methyl ester in reactor 1 is pumped into reactor 2 through a delivery pump, and anhydrous methanol is added to reactor 2 through heat exchanger 1 for mixing and reaction to carry out a second esterification reaction. The reaction temperature of reactor 1 is 80°C;

[0051] (5) A small amount of water generated during the reaction in reactor 2 evaporates along with the methanol gas, and the water in the mixed gas phase of methanol and water is absorbed by the desiccant in the dryer to improve the purity of the methanol. The water is then exchanged with the anhydrous methanol passing through heat exchanger 1 and then enters reactor 1.

[0052] (6) A small amount of water generated during the reaction in reactor 1 evaporates along with the methanol gas and exchanges heat with the anhydrous methanol passing through heat exchanger 2. The condensed methanol is output as aqueous methanol for storage or further distillation and dehydration for reuse;

[0053] (7) Stop the reaction and discharge high-purity biodiesel from reactor 2.

[0054] Embodiment 5 of a method for effectively promoting esterification reaction of the present invention comprises the following steps:

[0055] (1) Methanol enters reactor 2 after passing through heat exchanger 2 and heat exchanger 1, and heat is exchanged between liquid methanol and gaseous methanol;

[0056] (2) Add fatty acid to reactor 1, add acid catalyst and methanol to the mixing tank and fully dissolve and mix; the amount of catalyst added is 0.2% of the weight of the fat, and the amount of methanol added is 18% of the fatty acid;

[0057] (3) The fatty acid in the reactor 1 is mixed with the aqueous methanol from the heat exchanger 1 and the catalyst from the mixing tank to react and perform the first esterification reaction. The reaction temperature of the reactor 1 is 87°C.

[0058] (4) The methyl ester in reactor 1 is pumped into reactor 2 through a delivery pump, and anhydrous methanol is added to reactor 2 through heat exchanger 1 for mixing and reaction to carry out a second esterification reaction. The reaction temperature of reactor 1 is 87°C;

[0059] (5) A small amount of water generated during the reaction in reactor 2 evaporates along with the methanol gas, and the water in the mixed gas phase of methanol and water is absorbed by the desiccant in the dryer to improve the purity of the methanol. The water is then exchanged with the anhydrous methanol passing through heat exchanger 1 and then enters reactor 1.

[0060] (6) A small amount of water generated during the reaction in reactor 1 evaporates along with the methanol gas and exchanges heat with the anhydrous methanol passing through heat exchanger 2. The condensed methanol is output as aqueous methanol for storage or further distillation and dehydration for reuse;

[0061] (7) Stop the reaction and discharge high-purity biodiesel from reactor 2.

[0062] Embodiment 6 of a method for effectively promoting esterification reaction of the present invention comprises the following steps:

[0063] (1) Methanol enters reactor 2 after passing through heat exchanger 2 and heat exchanger 1, and heat is exchanged between liquid methanol and gaseous methanol;

[0064] (2) Add fatty acid to reactor 1, add acid catalyst and methanol to the mixing tank and fully dissolve and mix; the amount of catalyst added is 0.3% of the weight of the fat, and the amount of methanol added is 20% of the fatty acid;

[0065] (3) The fatty acid in the reactor 1 is mixed with the aqueous methanol from the heat exchanger 1 and the catalyst from the mixing tank to react and perform the first esterification reaction. The reaction temperature of the reactor 1 is 95°C.

[0066] (4). Pump the methyl ester in Reactor 1 into Reactor 2 through a transfer pump, add anhydrous methanol in Reactor 2 through Heat Exchanger 1 for mixing and reaction to conduct the second esterification reaction, and the reaction temperature of Reactor 1 is 95 °C;

[0067] (5). A small amount of water generated during the reaction in Reactor 2 evaporates together with the methanol gas. The water in the methanol and water mixed gas phase is absorbed by the desiccant in the dryer to improve the purity of methanol, and then exchanges heat with the anhydrous methanol passing through Heat Exchanger 1, and then enters Reactor 1;

[0068] (6). A small amount of water generated during the reaction in Reactor 1 evaporates together with the methanol gas, exchanges heat with the anhydrous methanol passing through Heat Exchanger 2, and after condensation, the methanol is output and stored for standby or recycled by rectification for dehydration;

[0069] (7). Stop the reaction and discharge high-purity biodiesel from Reactor 2.

[0070] The embodiment of the present invention uses two-stage reactors for reaction. Of course, more-stage reactors can also be used for multi-stage reaction to further effectively promote the esterification reaction. The whole process has continuous feeding, continuous reaction, and continuous discharging, and the preparation effects of glycerol butyrate and biodiesel are good.

Claims

1. A method for effectively promoting esterification reaction, characterized in that The esterification reaction system includes a reactor 1, a reactor 2, a dryer, a heat exchanger 1, a heat exchanger 2, a mixing tank, and a delivery pump. The mixing tank is connected to the reactor 1 through a pipeline, the reactor 1 is connected to the reactor 2 through a delivery pump, the reactor 2 is connected to the heat exchanger 1 through a dryer, and the heat exchanger 1 is also connected to the reactor 2 through another pipeline; the heat exchanger 1 is connected to the reactor 1 through a pipeline, the heat exchanger 1 is connected to the heat exchanger 2 through a pipeline, and the heat exchanger 2 is connected to the reactor 1 through a pipeline; the catalyst input pipeline is connected to the mixing tank, the fatty acid or glycerol input pipeline is connected to the reactor 1, the butyric acid or methanol input pipeline is respectively connected to the mixing tank and the heat exchanger 2, and the heat exchanger 2 is also connected to the aqueous butyric acid or methanol output pipeline; The method for effectively promoting the esterification reaction comprises the following steps: (1) Butyric acid or methanol enters reactor 2 after passing through heat exchanger 2 and heat exchanger 1, and heat is exchanged between liquid phase butyric acid or methanol and gas phase butyric acid or methanol; (2) Add glycerol or fatty acid to the reactor 1, add catalyst and butyric acid or catalyst and methanol to the mixing tank and fully dissolve and mix; (3) Mixing and reacting the glycerol or fatty acid in the reactor 1 with the aqueous butyric acid or methanol from the heat exchanger 1 and the catalyst from the mixing tank to perform a first esterification reaction; (4) The butyric acid glyceride or methyl ester in the reactor 1 is pumped into the reactor 2 through a delivery pump, and anhydrous butyric acid or anhydrous methanol is added to the reactor 2 through a heat exchanger 1 for mixing and reaction to carry out a second esterification reaction; (5) A small amount of water generated during the reaction in the reactor 2 evaporates together with the butyric acid gas or the methanol gas, and is absorbed by the desiccant in the dryer to improve the purity of the butyric acid or the methanol, and then passes through the heat exchanger 1 to exchange heat with the anhydrous butyric acid or the anhydrous methanol passing through the heat exchanger 1, and then enters the reactor 1; (6) A small amount of water generated during the reaction in reactor 1 evaporates together with the butyric acid or methanol gas, and exchanges heat with the anhydrous butyric acid or anhydrous methanol passing through heat exchanger 2. After condensation, the butyric acid or methanol is output as aqueous butyric acid or aqueous methanol for storage or further distillation and dehydration for reuse; (7) Stop the reaction and discharge high-purity tributyrin or biodiesel from reactor 2.

2. The method for effectively promoting an esterification reaction according to claim 1, wherein In the step (2), when producing tributyrin, the catalyst is an acidic catalyst, the amount of the catalyst added is 0.1-0.5% of the weight of glycerol, and the molar ratio of the amount of butyric acid added to glycerol is 1.5-2:1; the reaction temperature of the reactor 1 and the reactor 2 in the steps (2) and (3) are both 150-180°C.

3. A method for effectively promoting an esterification reaction according to claim 1, characterized in that In the step (2), when producing biodiesel, the catalyst is an acidic catalyst, the amount of the catalyst added is 0.1-0.3% of the weight of the fatty acid, and the amount of methanol added is 15-20% of the fatty acid; the reaction temperature of the reactor 1 and the reactor 2 in the step (2) and step (3) are both 80-95°C.

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