Continuous production equipment and method for biodiesel

Abstract

The invention discloses a continuous production equipment and production method of biodiesel. The continuous production equipment adopts a jet loop reactor and a filter tube; the filter tube is composed of an inner tube and an outer tube of a tubular filter element; the bottom of the reactor is connected to a heat exchanger through a circulating pump; the heat exchanger is connected to a venturi ejector arranged at the top of the reactor through the inner tube of the filter tube and a feed pipe in sequence; the venturi ejector includes an inlet section, a nozzle, a mixing section and a diffusion section that are connected in sequence, and the outer periphery of the inlet section and the nozzle is provided with a tapered annular air chamber, which is connected to the mixing section, and the air chamber is connected to an air inlet arranged at the top of the reactor through a gas circulation pipe; a feed port is provided on the feed pipe; and a discharge port is provided on the outer tube of the filter tube. The invention adopts a jet loop reactor, solid alkali is used as a catalyst, methanol and palm oil are used as raw materials, and the powerful mass transfer effect of the venturi jet reactor is fully utilized, the reaction time is effectively shortened, and the yield is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical production, and in particular relates to a process for continuously producing biodiesel by adopting a new type of reactor equipment, namely a loop reactor. Background Art

[0002] Biodiesel is a fatty acid methyl ester obtained through ester exchange reaction with vegetable oil or animal fat as the main raw materials. As a green renewable resource, it has become an ideal substitute for petrochemical diesel due to its unique properties.

[0003] In the preparation process of biodiesel (fatty acid methyl ester), the reaction rate is very low because triglyceride fatty acids and methanol are not well soluble in each other. When using traditional stirred tanks as reactors, ethers that are soluble in each other are usually added to form a homogeneous reaction system to accelerate the reaction rate. The catalysts used are mostly homogeneous alkaline catalysts or acid catalysts. This process condition has the problems of complex process, poor renewability, difficult separation and purification of products, cumbersome post-processing, large discharge volume, and easy generation of three wastes, which greatly limits its application.

[0004] The existing technology uses a stirred tank to prepare biodiesel, which takes a long time and requires manual feeding of materials and collection of products, making it difficult to achieve continuous production, with high labor costs and difficulty in industrial promotion. Summary of the invention

[0005] The purpose of the present invention is to solve the defects in the prior art and provide a process capable of continuously producing biodiesel. The biodiesel continuous production process has a high degree of automation and effectively improves the production capacity.

[0006] In order to achieve the above-mentioned purpose, the present invention provides a continuous production equipment for biodiesel, which adopts a jet loop reactor; wherein the jet loop reactor includes a reactor, a circulation pump, a heat exchanger and a venturi injector; the continuous production equipment of the present invention also includes a filter tube; the filter tube is composed of an inner tube formed by a tubular filter element and an outer tube sleeved on the outside, and the outer tube is sealed and connected to the inner tube at both ends; the bottom of the reactor is connected to the heat exchanger through the circulation pump; the heat exchanger is connected to the venturi injector arranged at the top of the reactor through the inner tube of the filter tube and the feed pipe in turn; the venturi injector includes an inlet section, a nozzle, a mixing section and a diffusion section that are connected in turn, wherein the inlet section and the nozzle are in a tapered tubular shape, and the outer periphery of the inlet section and the nozzle is provided with a tapered annular air chamber, the air chamber is connected to the mixing section, and the air chamber is connected to the air inlet arranged on the upper part of the reactor through a gas circulation pipe; the diffusion section is in a gradually expanding tubular shape; a feed port is provided on the feed pipe; and a discharge port is provided on the outer tube of the filter tube.

[0007] The jet loop reactor is a new type of reactor system. The reaction liquid circulates in the loop at a large flow rate and is ejected at high speed through a Venturi ejector (mixer), forming a negative pressure at the working nozzle. The process gas is sucked into the ejector to form micron-sized bubbles with a large specific surface area, increasing the gas-liquid contact and accelerating the gas-liquid (or gas-liquid-solid) multiphase reaction rate.

[0008] The present invention utilizes the effect of bubbles in the jet loop reactor to segment and shear the liquid in the jet mixing area (mixing section and diffusion section of the venturi ejector) and the liquid in the reactor, thereby promoting diffusion and mass transfer between the liquids, strongly stirring the heterogeneous system formed by methanol-triglyceride-solid base catalyst-nitrogen for biodiesel preparation of the present invention, and accelerating the chemical reaction speed.

[0009] The present invention uses solid alkali as a catalyst to replace the homogeneous alkali catalyst in the traditional process, and is easy to recycle after the reaction is completed. At the same time, combined with the filter tube arranged between the heat exchanger and the venturi injector, the prepared biodiesel can be continuously sampled after filtering the solid alkali, and the solid alkali can be returned to the reactor for recycling, and the raw materials can be continuously fed through the feed port, effectively realizing automated and continuous production.

[0010] The feed ports include methanol feed port and palm oil feed port; the upper part of the reactor is also provided with a catalyst feed port. Methanol, palm oil and catalyst are fed separately, which is convenient for continuous injection of raw materials and adjustment of the feed amount of different raw materials according to the progress of the reaction.

[0011] In some embodiments, it is more preferred that the specifications of the Venturi injector are: inner diameter of the inlet section opening: inner diameter of the nozzle: inner diameter of the air chamber closing: length of the mixing section: length of the diffusion section = 38: (1.5~4): (2~6): (90~190): (800~1600), and the opening angle of the diffusion section is 8~20°.

[0012] By improving the design of the specifications and dimensions of the venturi injector, it is made more suitable for the preparation of the biodiesel of the present invention, and the reaction rate is further improved to obtain a higher equipment capacity.

[0013] In some embodiments, more preferably, the specifications of the Venturi injector are: inlet section opening inner diameter: nozzle inner diameter: air chamber closing inner diameter: mixing section length: diffusion section length = 38:3:4: (140~170): (1200~1400), and the opening angle of the diffusion section is 14~18°.

[0014] In some embodiments, the most preferred specifications of the Venturi injector are: inlet section opening inner diameter: nozzle inner diameter: air chamber closing inner diameter: mixing section length: diffusion section length = 38:3:4:140:1200, and the opening angle of the diffusion section is 14°.

[0015] The present invention also provides a continuous production method of biodiesel using the above-mentioned continuous production equipment. The continuous production method uses methanol and palm oil as raw materials, solid alkali as catalyst, and uses the jet loop reactor for continuous production: methanol, palm oil and catalyst are pre-charged in a reactor, and nitrogen is introduced through the air inlet to maintain the reaction pressure in the jet loop reactor; and during continuous production, methanol and palm oil are continuously fed through the feed port, and after the materials react in the reactor through a venturi ejector, they enter a heat exchanger from the bottom through a circulation pump, and a part of the materials containing solid alkali enters the venturi ejector through the feed pipe through the inner tube of the filter core tube, and the other part enters the outer tube of the filter core tube after filtration, and is continuously produced from the discharge port; the production amount of the discharge port is equal to the feed amount of the raw materials methanol and palm oil, and the reaction residence time is controlled by adjusting the feed amount; and the pressure in the reaction system is maintained unchanged.

[0016] The present invention utilizes the powerful mass transfer effect of the Venturi jet reactor, and pre-fills the reaction system with nitrogen (as a process gas). Through the action of the Venturi jet, nitrogen inhaled into the liquid material promotes the mutual diffusion between biodiesel and methanol, and fully contacts with the active center of the catalyst, strengthens the mass transfer process between the reaction materials, effectively improves the reaction rate, and improves the yield. At the same time, the present invention uses solid alkali as a catalyst, methanol and palm oil as raw materials, and the solid alkali used is easy to separate from the product, the catalyst is easy to regenerate after the reaction, and has little corrosion to the equipment. Palm oil and anhydrous methanol continuously enter the reaction system, biodiesel-glycerol-methanol is continuously extracted, the conversion rate is stable, and continuous automated production is effectively realized.

[0017] In some embodiments, it is more preferred that during continuous production, the reaction residence time is controlled to be 30 to 90 minutes by adjusting the feed amounts of raw materials methanol and palm oil.

[0018] The present invention obtains a relatively preferred yield of biodiesel by optimizing the reaction residence time.

[0019] In some embodiments, preferably, when the volume of the reactor is 5 L, the feed rate of methanol is controlled to be 11-28 ml / min, and the feed rate of palm oil is controlled to be 34-84 ml / min; the linear velocity of the fluid at the nozzle of the venturi injector is controlled to be 90-130 m / s.

[0020] In some embodiments, preferably, methanol and palm oil are fed in a molar ratio of (2-13):1; during pre-feeding, the amount of catalyst added is 1-4% of the mass of palm oil.

[0021] During continuous production, the reaction temperature is controlled to be 60-110°C and the reaction pressure is controlled to be 0.5-1.5MPa.

[0022] The present invention obtains process conditions more suitable for the preparation of biodiesel of the present invention by exploring production process parameters, thereby further improving production efficiency.

[0023] In some embodiments, more preferably, methanol and palm oil are fed in a molar ratio of 8:1; during pre-feeding, the amount of catalyst added is 2% of the mass of palm oil; and during continuous production, the reaction temperature is controlled to 85°C and the reaction pressure is controlled to 0.9MPa.

[0024] Solid alkali can be KF / MgO, KF / CaO, KNO3 / Al2O3, KOH / Al2O3, KF / Al2O3 or K2CO3 / Al2O3, etc.; KF / MgO uses MgO as a carrier, on which is loaded KF which is 60% of the mass of MgO; KNO3 / Al2O3 uses Al2O3 as a carrier, on which is loaded KNO3 which is 20% of the mass of Al2O3; KOH / Al2O3 uses Al2O3 as a carrier, on which is loaded KOH which is 15% of the mass of Al2O3; KF / CaO uses CaO as a carrier, on which is loaded KF which is 14% of the mass of CaO.

[0025] In some embodiments, it is more preferred that the solid base adopts KF / Al2O3 or K2CO3 / Al2O3; KF / Al2O3 uses Al2O3 as a carrier, and loads 15% by mass of KF thereon; K2CO3 / Al2O3 uses Al2O3 as a carrier, and loads 20% by mass of K2CO3 thereon.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] 1. The present invention adopts a jet loop reactor, solid base as catalyst, methanol and palm oil as raw materials, and fully utilizes the powerful mass transfer effect of the Venturi jet reactor, effectively shortens the reaction time, and improves the yield; and replaces the homogeneous base catalyst with a solid base catalyst, which has the advantages of easy separation from the product, easy regeneration of the catalyst after the reaction, and low corrosion to the equipment.

[0028] 2. In the biodiesel continuous production device of the present invention, palm oil and anhydrous methanol continuously enter the reaction system, and biodiesel-glycerol-methanol is continuously produced, with a stable conversion rate; compared with the traditional intermittent process, the operation steps are simple, and continuous automated production is effectively realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural schematic diagram of the biodiesel continuous production equipment of the present invention;

[0030] Figure 2 for Figure 1 Schematic diagram of the structure of the Chinese Qiuli injector.

[0031] In the figure, 1-reactor, 2-Venturi ejector, 3-heat exchanger, 4-circulation pump, 5-gas circulation pipe, 6-inlet section, 7-mixing section, 8-diffusion section, 9-nozzle, 10-air chamber, 11-filter tube, 12-discharge port, 13-methanol feed port, 14-palm oil feed port, 15-catalyst feed port, 16-air inlet. DETAILED DESCRIPTION

[0032] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] 1. Catalyst preparation

[0034] Reagents used:

[0035] KF·2H2O (Sinopharm Chemical Reagent Co., Ltd. AR);

[0036] K2CO3 (Sinopharm Chemical Reagent Co., Ltd. AR);

[0037] KNO3 (Sinopharm Chemical Reagent Co., Ltd. AR);

[0038] KOH (Sinopharm Chemical Reagent Co., Ltd. AR);

[0039] MgO powder S BET =186m 2 / g(Sinopharm Chemical Reagent Co., Ltd.AR);

[0040] CaO (Sinopharm Chemical Reagent Co., Ltd. AR);

[0041] The alumina carrier comes from the Jinling Petrochemical Alkylbenzene Plant, with a diameter of 1-2 mm and is spherical and ground into powder. BET =211m 2 / g.

[0042] Preparation process of KF / Al2O3: Grind a certain amount of alumina into powder, sieve out 100-200 mesh powder, add KF·2H2O with a KF mass of 15% of the alumina powder mass and add appropriate amount of distilled water, stir evenly and let stand for 10 hours, dry at 60℃ for 24 hours, heat to 550℃ at 5℃ / min, and keep the temperature constant for 6 hours, take out and cool in a dryer for use.

[0043] Preparation process of K2CO3 / Al2O3: Grind a certain amount of alumina into powder, sieve out 100-200 mesh powder, add K2CO3 which is 20% of the mass of alumina powder and add appropriate amount of distilled water, stir evenly and let stand for 10 hours, dry at 60℃ for 24 hours, heat to 600℃ at 5℃ / min, and keep the temperature constant for 5 hours, take out and cool in a dryer for later use.

[0044] Preparation process of KF / MgO: adopt equal volume impregnation method, weigh a certain amount of KF·2H2O and dissolve it in an appropriate amount of deionized water, add carrier MgO powder, and make the mass of KF account for 60% of the mass of MgO, stir and evaporate to dryness in a water bath at 80℃, increase the temperature to 550℃ at 5℃ / min, and keep the temperature constant for 4h, take out and cool in a desiccator for use.

[0045] Preparation process of KF / CaO: adopt equal volume impregnation method, weigh a certain amount of KF·2H2O and dissolve it in an appropriate amount of deionized water, add carrier CaO powder, and make the mass of KF account for 14% of the mass of CaO, stir and evaporate to dryness in a water bath at 80℃, increase the temperature to 550℃ at 5℃ / min, and keep the temperature constant for 4h, take out and cool in a desiccator for use.

[0046] Preparation process of KNO3 / Al2O3: adopt equal volume impregnation method, take a certain amount of alumina and grind it into powder, sieve out 100-200 mesh powder, add KNO3 with a mass of 20% of the mass of alumina powder and add appropriate amount of distilled water, stir evenly and let stand for 10h, dry at 60℃ for 24h, heat to 600℃ at 5℃ / min, and keep the temperature constant for 6h, take out and cool in the dryer for use.

[0047] KOH / Al2O3 preparation process: adopt equal volume impregnation method, take a certain amount of alumina and grind it into powder, sieve out 100-200 mesh powder, add KOH with KF mass equal to 15% of the mass of alumina powder and add appropriate amount of distilled water, stir evenly and let stand for 10 hours, dry at 60℃ for 24 hours, heat to 600℃ at 5℃ / min, and keep the temperature constant for 6 hours, take out and cool in a dryer for use.

[0048] 2. Biodiesel Continuous Production Equipment

[0049] like Figure 1 As shown, the biodiesel production of the present invention is carried out by using a jet loop reactor. The loop reactor includes five parts: a reactor 1, a venturi ejector 2, a heat exchanger 3, a circulation pump 4, and a filter tube 11.

[0050] When the equipment is working, the circulation pump 4 is started. The reaction fluid circulates in the loop at a large flow rate, and the Venturi ejector 2 ejects at a high speed, forming a negative pressure at the working nozzle, so that the gas (process gas) is sucked into the Venturi ejector. A gas circulation pipe 5 is provided on one side of the top of the reactor 1 and is connected to the air inlet, so that a gas circuit circulation can be formed locally. Tiny bubbles with a large specific surface area are formed in the Venturi ejector, and the mass transfer process between the gas-liquid-solid heterogeneous reaction materials is enhanced by dividing and stirring the liquid flow, thereby shortening the reaction time. The lower end of the Venturi ejector is located below the liquid level, and the gas-liquid-solid mixed material impacts the material in the reactor, which promotes the dispersion and mixing effect and promotes the further reaction. The material enters the heat exchanger 3 from the bottom of the reactor through the circulation pump 4, and passes through the filter tube 11. After a part of the material filters out the solid catalyst, it is continuously extracted from the discharge port 12, and the other part of the material containing the solid catalyst enters the Venturi ejector 2 from the top of the reactor 1. Heat exchanger 3 removes or provides heat released or absorbed during the reaction, and controls the reaction temperature fluctuation to ±1°C.

[0051] During the reaction, raw materials palm oil and methanol (room temperature) continuously enter the reactor from the top of the reactor, and the product is extracted from the discharge port after the filter tube (filter tube filter element pore size is 10 microns) at the upper part of the heat exchanger. A pressure regulating device (not shown) is used to control and maintain a certain pressure in the reaction system. During continuous production, the amount of raw materials palm oil and methanol entering is equal to the amount of product mixture extracted, that is, the liquid level in the reactor is maintained at a fixed height to ensure continuous and stable production.

[0052] The heat exchanger in this patent can be a tubular heat exchanger or a plate heat exchanger.

[0053] Combination Figure 2 In the present invention, the Venturi ejector is specifically composed of an inlet section 6 in the shape of a tapered tube, a mixing section 7, a diffusion section 8, a nozzle 9 and an air chamber 10. Figure 1 As shown, the side of the gas chamber 10 is connected to the top gas inlet of the reactor 1 through the gas circulation pipe 5, providing a local gas circulation space.

[0054] Screening Example 1

[0055] Example of screening reaction raw material ratio

[0056] Anhydrous methanol, palm oil treated by reflux deacidification with sodium hydroxide, and KF / Al2O3 catalyst are added into the reactor (5L) through the methanol feed port 13, palm oil feed port 14, and catalyst feed port 15, respectively; nitrogen is introduced into the reaction system through the air inlet 16 until the system pressure reaches 1MPa, the methanol feed port 13, palm oil feed port 14, catalyst feed port 15, and discharge port 12 are closed, and the circulation pump 4 is turned on to allow the fluid in the reactor to flow slowly, vent, and replace the air in the jet loop reactor 6 times. After the last replacement, the reaction system is kept at a certain pressure, and nitrogen is immediately added to the reaction pressure after heating to the reaction temperature (heating time is about 10min), and the circulation pump 4 is adjusted until the flow rate at the nozzle of the venturi ejector reaches a certain value, which is recorded as the reaction start time.

[0057] When the reaction is finished, immediately reduce the flow rate of the circulating pump 4 and quickly cool to room temperature (cooling time is about 10 minutes). Vent the gas in the reactor and release the product in the reactor. Take part of the product and centrifuge it for stratification, take the upper layer for vacuum distillation and purification, and calculate the actual yield based on the mass of biodiesel obtained by the final distillation and the mass of palm oil in the reaction raw materials.

[0058] In this embodiment, the addition ratio of methanol and palm oil is changed to compare the actual yield of biodiesel. The remaining production process parameters are: the amount of catalyst is 2% of the mass of palm oil, the reaction pressure is 0.9MPa, the reaction temperature is 65℃, the reaction time is 40min, the specifications and dimensions of the venturi injector are: the opening inner diameter of the inlet section: the nozzle inner diameter: the closing inner diameter of the air chamber: the length of the mixing section: the length of the diffusion section = 38:2:3:150:1000, the opening angle of the diffusion section is 10°, and the linear velocity of the fluid at the nozzle of the venturi injector during the reaction is 95m / s. The mixture after the reaction is centrifuged and stratified, and the yellow transparent liquid biodiesel is obtained by vacuum distillation, and the yield of biodiesel is calculated according to the ratio of the products taken.

[0059] The actual yields obtained by adding different raw materials are shown in Table 1 below.

[0060] Table 1 Screening results of methanol / palm oil ratio (alcohol-oil ratio)

[0061]

[0062] It can be seen from the above table that with the increase of alcohol-to-oil ratio, the actual yield gradually increases, but when the alcohol-to-oil ratio is higher than 8:1, the yield decreases accordingly; and when the alcohol-to-oil ratio is too small (2:1) or too large (13:1), the actual yield is greatly reduced. Therefore, the alcohol-to-oil molar ratio should be controlled to (3-12):1 to obtain a better yield, and the optimal alcohol-to-oil ratio is 8:1.

[0063] Screening Example 2

[0064] Reaction temperature screening example

[0065] The preparation method of biodiesel is the same as that in Example 1.

[0066] In this embodiment, the reaction temperature is changed to compare the actual yield of biodiesel. The remaining production process parameters are: alcohol-oil ratio is 8:1 (methanol addition amount is 770g, palm oil addition amount is 2700g), the amount of catalyst used is 2% of the mass of palm oil, the reaction pressure is 0.9MPa, the reaction time is 40min, the specifications and dimensions of the venturi injector are: inlet section opening inner diameter: nozzle inner diameter: air chamber closing inner diameter: mixing section length: diffusion section length = 38:2:3:150:1000, the opening angle of the diffusion section is 10°, and the linear velocity of the fluid at the nozzle of the venturi injector during the reaction is 95m / s. The mixture after the reaction is centrifuged and stratified, and the yellow transparent liquid biodiesel is obtained by vacuum distillation, and the biodiesel yield is calculated according to the ratio of the products taken.

[0067] The actual yields obtained at different reaction temperatures are shown in Table 2 below.

[0068] Table 2 Screening results of reaction temperature

[0069] Reaction temperature℃ Actual yield% 50 56.6 65 82.7 75 84.2 85 88.6 95 83.1 105 79.4 120 70.5

[0070] As can be seen from the above table, with the increase of reaction temperature, the actual yield gradually increases, but when the reaction temperature is higher than 85°C, the yield continues to decrease. At the same time, when the reaction temperature is too high (120°C) or too low (50°C), the yield decreases significantly. Therefore, it is preferred to control the temperature between 60-110°C, and the optimal reaction temperature is 85°C.

[0071] Screening Example 3

[0072] Reaction pressure screening example

[0073] The preparation method of biodiesel is the same as that in Example 1.

[0074] In this embodiment, the reaction pressure is changed to compare the actual yield of biodiesel. The remaining production process parameters are: alcohol-oil ratio is 8:1 (methanol addition amount is 770g, palm oil addition amount is 2700g), the amount of catalyst used is 2% of the mass of palm oil, the reaction temperature is 85°C, the reaction time is 40min, the specifications and dimensions of the venturi injector are: inlet section opening inner diameter: nozzle inner diameter: air chamber closing inner diameter: mixing section length: diffusion section length = 38:2:3:150:1000, the opening angle of the diffusion section is 10°, and the linear velocity of the fluid at the nozzle of the venturi injector during the reaction is 95m / s. The mixture after the reaction is centrifuged and stratified, and the yellow transparent liquid biodiesel is obtained by vacuum distillation, and the biodiesel yield is calculated according to the ratio of the products taken.

[0075] The actual yields obtained at different reaction pressures are shown in Table 3 below.

[0076] Table 3 Screening results of reaction pressure

[0077] Reaction pressure MPa Actual yield% 0.3 72.8 0.5 78.6 0.7 83.5 0.9 88.6 1.2 87.4 1.4 82.3 1.6 76.5

[0078] As can be seen from the table above, with the increase of reaction pressure, the actual yield gradually increases, but when the reaction pressure is greater than 0.9 MPa, the yield continues to decrease; and when the reaction pressure is too high (1.6 MPa) or too low (0.3 MPa), the yield is significantly reduced. Therefore, the preferred control pressure is 0.5-1.5 MPa, and the optimal reaction pressure is 0.9 MPa.

[0079] Preparation Example 1

[0080] Pre-feeding: according to the raw material ratio, anhydrous methanol, palm oil after reflux deacidification by sodium hydroxide, and KF / Al2O3 catalyst are added into the reactor (5L) through the methanol feed port 13, palm oil feed port 14, and catalyst feed port 15 respectively; nitrogen is introduced into the reaction system through the air inlet 16 to a system pressure of 1MPa, and the circulating pump 4 is turned on to allow the fluid in the reactor to flow slowly, vent, and repeat the replacement of air in the injection loop reactor 3 times. After the last replacement, the reaction system is kept at a certain pressure, and the temperature is raised to the reaction temperature (heating time is about 10min), and nitrogen is immediately added to the reaction pressure, and the circulating pump 4 is adjusted until the flow rate at the nozzle of the venturi ejector reaches a certain value, which is recorded as the reaction start time.

[0081] Continuous production: The flow rates of methanol and palm oil are adjusted according to the specified molar ratio, and the materials are continuously fed through the methanol feed port 13 and the palm oil feed port 14, and the product is continuously taken out through the discharge port 12, and the total feed flow rate is kept balanced with the withdrawal flow rate to keep the volume in the reactor unchanged, and the specified residence time = the volume of the material in the reactor / the product withdrawal flow rate.

[0082] Take part of the product and centrifuge to separate the layers, take the upper layer for vacuum distillation and purification, and calculate the actual yield based on the mass of biodiesel obtained by the final distillation and the mass of palm oil in the reaction raw materials.

[0083] In this embodiment, the molar ratio of methanol to palm oil is 8:1 (methanol pre-feeding amount is 770g, palm oil pre-feeding amount is 2700g), the pre-feeding amount of KF / Al2O3 catalyst is 1.5% (40.5g) of the mass of palm oil, the reaction pressure is 0.9MPa, the reaction temperature is 85°C, the specifications of the venturi injector are: inlet section opening inner diameter: nozzle inner diameter: chamber closing inner diameter: mixing section length: diffusion section length = 38:2.5:3.5:140:1300, the opening angle of the diffusion section is 15°, and the linear velocity of the fluid at the nozzle of the venturi injector during the reaction is 110m / s. In continuous production, the feed rate of methanol is controlled to be 11.47ml / min, the feed rate of palm oil is controlled to be 34.53ml / min, and the residence time is 85min. The mixture after the reaction was centrifuged and stratified, and then distilled under reduced pressure to obtain yellow transparent liquid biodiesel. The yield of biodiesel was calculated to be 93.2% based on the ratio of the products taken.

[0084] Preparation Example 2

[0085] The preparation method is the same as that of Preparation Example 1.

[0086] In this embodiment, the molar ratio of methanol to palm oil is 8:1 (methanol pre-feeding amount is 770g, palm oil pre-feeding amount is 2700g), the pre-feeding amount of KF / Al2O3 catalyst is 1.8% (48.6g) of the mass of palm oil, the reaction pressure is 0.9MPa, the reaction temperature is 85°C, the specifications and dimensions of the venturi injector are: inlet section opening inner diameter: nozzle inner diameter: chamber closing inner diameter: mixing section length: diffusion section length = 38:2:3:150:1000, the opening angle of the diffusion section is 11°, and the linear velocity of the fluid at the nozzle of the venturi injector during the reaction is 125m / s. In continuous production, the feed rate of methanol is controlled to be 13.00ml / min, the feed rate of palm oil is controlled to be 39.13ml / min, and the residence time is 75min. The mixture after the reaction was centrifuged and stratified, and then distilled under reduced pressure to obtain yellow transparent liquid biodiesel. The yield of biodiesel was calculated to be 95.6% based on the proportion of the products.

[0087] Preparation Example 3

[0088] The preparation method is the same as that of Preparation Example 1.

[0089] In this embodiment, the molar ratio of methanol to palm oil is 8:1 (methanol pre-feeding amount is 770g, palm oil pre-feeding amount is 2700g), the pre-feeding amount of KF / Al2O3 catalyst is 2.0% (54g) of the mass of palm oil, the reaction pressure is 0.9MPa, the reaction temperature is 85℃, the specifications and dimensions of the venturi injector are: inlet section opening inner diameter: nozzle inner diameter: air chamber closing inner diameter: mixing section length: diffusion section length = 38:3:4:140:1200, the opening angle of the diffusion section is 14°, and the fluid linear velocity at the nozzle of the venturi injector during the reaction is 115m / s. And in continuous production, the feed rate of methanol is controlled to be 16.24ml / min, the feed rate of palm oil is controlled to be 48.91ml / min, and the residence time is 60min. The mixture after reaction is centrifuged and stratified, and the yellow transparent liquid biodiesel is obtained by vacuum distillation. The biodiesel yield is calculated to be 97.9% based on the product ratio.

[0090] Preparation Example 4

[0091] The preparation method is the same as that of Preparation Example 1.

[0092] In this embodiment, the molar ratio of methanol to palm oil is 8:1 (methanol pre-feeding amount is 770g, palm oil pre-feeding amount is 2700g), the pre-feeding amount of KF / Al2O3 catalyst is 2.5% (67.5g) of the mass of palm oil, the reaction pressure is 0.9MPa, the reaction temperature is 85°C, the specifications and dimensions of the venturi injector are: inlet section opening inner diameter: nozzle inner diameter: chamber closing inner diameter: mixing section length: diffusion section length = 38:3:4:170:1400, the opening angle of the diffusion section is 18°, and the linear velocity of the fluid at the nozzle of the venturi injector during the reaction is 105m / s. In continuous production, the feed rate of methanol is controlled to be 19.49ml / min, the feed rate of palm oil is controlled to be 58.70ml / min, and the residence time is 50min. The mixture after the reaction was centrifuged and stratified, and then distilled under reduced pressure to obtain yellow transparent liquid biodiesel. The yield of biodiesel was calculated to be 96.5% based on the ratio of the products taken.

[0093] Preparation Example 5

[0094] The preparation method is the same as that of Preparation Example 1.

[0095] In this embodiment, the molar ratio of methanol to palm oil is 8:1 (methanol pre-feeding amount is 770g, palm oil pre-feeding amount is 2700g), the pre-feeding amount of KF / Al2O3 catalyst is 3.0% (81g) of the mass of palm oil, the reaction pressure is 0.9MPa, the reaction temperature is 85°C, the specifications of the venturi injector are: inlet section opening inner diameter: nozzle inner diameter: chamber closing inner diameter: mixing section length: diffusion section length = 38:3.5:5:160:1500, the opening angle of the diffusion section is 15°, and the linear velocity of the fluid at the nozzle of the venturi injector during the reaction is 120m / s. In continuous production, the feed rate of methanol is controlled to be 24.37ml / min, the feed rate of palm oil is controlled to be 73.37ml / min, and the residence time is 40min. The mixture after the reaction was centrifuged and stratified, and then distilled under reduced pressure to obtain yellow transparent liquid biodiesel. The yield of biodiesel was calculated to be 96.1% based on the proportion of the products taken.

[0096] Preparation Example 6

[0097] The preparation method is the same as that of Preparation Example 1.

[0098] In this embodiment, the molar ratio of methanol to palm oil is 8:1 (methanol pre-feeding amount is 770g, palm oil pre-feeding amount is 2700g), the pre-feeding amount of KF / Al2O3 catalyst is 3.5% (94.5g) of the mass of palm oil, the reaction pressure is 0.9MPa, the reaction temperature is 85°C, the specifications of the venturi injector are: inlet section opening inner diameter: nozzle inner diameter: chamber closing inner diameter: mixing section length: diffusion section length = 38:3:4:105:1100, the opening angle of the diffusion section is 10°, and the linear velocity of the fluid at the nozzle of the venturi injector during the reaction is 123m / s. In continuous production, the feed rate of methanol is controlled to be 27.85ml / min, the feed rate of palm oil is controlled to be 83.85ml / min, and the residence time is 35min. The mixture after the reaction was centrifuged and stratified, and then distilled under reduced pressure to obtain yellow transparent liquid biodiesel. The yield of biodiesel was calculated to be 94.9% based on the ratio of the products taken.

[0099] Preparation Example 7

[0100] The preparation method is the same as that of Preparation Example 1.

[0101] In this embodiment, the molar ratio of methanol to palm oil is 8:1 (methanol pre-feeding amount is 770g, palm oil pre-feeding amount is 2700g), the catalyst is K2CO3 / Al2O3, the pre-feeding amount is 1.5% (40.5g) of the mass of palm oil, the reaction pressure is 0.9MPa, the reaction temperature is 85°C, the specifications and dimensions of the venturi injector are: inlet section opening inner diameter: nozzle inner diameter: chamber closing inner diameter: mixing section length: diffusion section length = 38:2.5:3.5:140:1300, the opening angle of the diffusion section is 15°, and the linear velocity of the fluid at the nozzle of the venturi injector during the reaction is 110m / s. In continuous production, the feed rate of methanol is controlled to be 11.47ml / min, the feed rate of palm oil is controlled to be 34.53ml / min, and the residence time is 85min. The mixture after the reaction was centrifuged and stratified, and then distilled under reduced pressure to obtain yellow transparent liquid biodiesel. The yield of biodiesel was calculated to be 92.9% based on the ratio of the products.

[0102] Preparation Example 8

[0103] The preparation method is the same as that of Preparation Example 1.

[0104] In this embodiment, the molar ratio of methanol to palm oil is 8:1 (methanol pre-feeding amount is 770g, palm oil pre-feeding amount is 2700g), the catalyst is K2CO3 / Al2O3, the pre-feeding amount is 1.8% (48.6g) of the mass of palm oil, the reaction pressure is 0.9MPa, the reaction temperature is 85°C, the specifications and dimensions of the venturi injector are: inlet section opening inner diameter: nozzle inner diameter: chamber closing inner diameter: mixing section length: diffusion section length = 38:2:3:150:1000, the opening angle of the diffusion section is 11°, and the fluid linear velocity at the nozzle of the venturi injector during the reaction is 125m / s. In continuous production, the feed rate of methanol is controlled to be 13.00ml / min, the feed rate of palm oil is controlled to be 39.13ml / min, and the residence time is 75min. The mixture after the reaction was centrifuged and stratified, and then distilled under reduced pressure to obtain yellow transparent liquid biodiesel. The yield of biodiesel was calculated to be 93.1% based on the proportion of the products.

[0105] Preparation Example 9

[0106] The preparation method is the same as that of Preparation Example 1.

[0107] In this embodiment, the molar ratio of methanol to palm oil is 8:1 (methanol pre-feeding amount is 770g, palm oil pre-feeding amount is 2700g), the catalyst is K2CO3 / Al2O3, the pre-feeding amount is 2.0% (54g) of the mass of palm oil, the reaction pressure is 0.9MPa, the reaction temperature is 85°C, the specifications and dimensions of the venturi injector are: inlet section opening inner diameter: nozzle inner diameter: air chamber closing inner diameter: mixing section length: diffusion section length = 38:3:4:140:1200, the opening angle of the diffusion section is 14°, and the fluid linear velocity at the nozzle of the venturi injector during the reaction is 115m / s. In continuous production, the feed rate of methanol is controlled to be 16.24ml / min, the feed rate of palm oil is controlled to be 48.91ml / min, and the residence time is 60min. The mixture after the reaction was centrifuged and stratified, and then distilled under reduced pressure to obtain yellow transparent liquid biodiesel. The yield of biodiesel was calculated to be 96.2% based on the ratio of the products.

[0108] Preparation Example 10

[0109] The preparation method is the same as that of Preparation Example 1.

[0110] In this embodiment, the molar ratio of methanol to palm oil is 8:1 (methanol pre-feeding amount is 770g, palm oil pre-feeding amount is 2700g), the catalyst is K2CO3 / Al2O3, the pre-feeding amount is 2.5% (67.5g) of the mass of palm oil, the reaction pressure is 0.9MPa, the reaction temperature is 85°C, the specifications and dimensions of the venturi injector are: inlet section opening inner diameter: nozzle inner diameter: chamber closing inner diameter: mixing section length: diffusion section length = 38:3:4:170:1400, the opening angle of the diffusion section is 18°, and the fluid linear velocity at the nozzle of the venturi injector during the reaction is 105m / s. In continuous production, the feed rate of methanol is controlled to be 19.49ml / min, the feed rate of palm oil is controlled to be 58.70ml / min, and the residence time is 50min. The mixture after the reaction was centrifuged and stratified, and then distilled under reduced pressure to obtain yellow transparent liquid biodiesel. The biodiesel yield was calculated to be 95.5% based on the ratio of the products taken.

[0111] Preparation Example 11

[0112] The preparation method is the same as that of Preparation Example 1.

[0113] In this embodiment, the molar ratio of methanol to palm oil is 8:1 (methanol pre-feeding amount is 770g, palm oil pre-feeding amount is 2700g), the catalyst is K2CO3 / Al2O3, the pre-feeding amount is 3.0% (81g) of the mass of palm oil, the reaction pressure is 0.9MPa, the reaction temperature is 85°C, the specifications and dimensions of the venturi injector are: inlet section opening inner diameter: nozzle inner diameter: chamber closing inner diameter: mixing section length: diffusion section length = 38:3.5:5:160:1500, the opening angle of the diffusion section is 15°, and the fluid linear velocity at the nozzle of the venturi injector during the reaction is 120m / s. In continuous production, the feed rate of methanol is controlled to be 24.37ml / min, the feed rate of palm oil is controlled to be 73.37ml / min, and the residence time is 40min. The mixture after the reaction was centrifuged and stratified, and then distilled under reduced pressure to obtain yellow transparent liquid biodiesel. The yield of biodiesel was calculated to be 92.2% based on the ratio of the products taken.

[0114] Preparation Example 12

[0115] The preparation method is the same as that of Preparation Example 1.

[0116] In this embodiment, the molar ratio of methanol to palm oil is 8:1 (methanol pre-feeding amount is 770g, palm oil pre-feeding amount is 2700g), the catalyst is K2CO3 / Al2O3, the pre-feeding amount is 3.5% (94.5g) of the mass of palm oil, the reaction pressure is 0.9MPa, the reaction temperature is 85°C, the specifications and dimensions of the venturi injector are: inlet section opening inner diameter: nozzle inner diameter: chamber closing inner diameter: mixing section length: diffusion section length = 38:3:4:105:1100, the opening angle of the diffusion section is 10°, and the fluid linear velocity at the nozzle of the venturi injector during the reaction is 123m / s. In continuous production, the feed rate of methanol is controlled to be 27.85ml / min, the feed rate of palm oil is controlled to be 83.85ml / min, and the residence time is 35min. The mixture after the reaction was centrifuged and stratified, and then distilled under reduced pressure to obtain yellow transparent liquid biodiesel. The yield of biodiesel was calculated to be 91.6% based on the ratio of the products.

[0117] Preparation Example 13

[0118] The preparation method is the same as that of Preparation Example 1.

[0119] In this embodiment, the molar ratio of methanol to palm oil is 8:1 (methanol pre-feeding amount is 770g, palm oil pre-feeding amount is 2700g), KF / CaO is used as catalyst, the pre-feeding amount is 2.0% (54g) of the mass of palm oil, the reaction pressure is 0.9MPa, the reaction temperature is 85°C, the specifications and dimensions of the venturi injector are: inlet section opening inner diameter: nozzle inner diameter: air chamber closing inner diameter: mixing section length: diffusion section length = 38:3:4:140:1200, the opening angle of the diffusion section is 14°, and the fluid linear velocity at the nozzle of the venturi injector during the reaction is 115m / s. And in continuous production, the feed rate of methanol is controlled to be 16.24ml / min, the feed rate of palm oil is controlled to be 48.91ml / min, and the residence time is 60min. The mixture after reaction is centrifuged and stratified, and the yellow transparent liquid biodiesel is obtained by vacuum distillation. The biodiesel yield is calculated to be 94.6% based on the ratio of the products taken.

[0120] Preparation Example 14

[0121] The preparation method is the same as that of Preparation Example 1.

[0122] In this embodiment, the molar ratio of methanol to palm oil is 8:1 (methanol pre-feeding amount is 770g, palm oil pre-feeding amount is 2700g), KF / MgO is used as catalyst, the pre-feeding amount is 2.0% (54g) of the mass of palm oil, the reaction pressure is 0.9MPa, the reaction temperature is 85°C, the specifications and dimensions of the venturi injector are: inlet section opening inner diameter: nozzle inner diameter: air chamber closing inner diameter: mixing section length: diffusion section length = 38:3:4:140:1200, the opening angle of the diffusion section is 14°, and the fluid linear velocity at the nozzle of the venturi injector during the reaction is 115m / s. And in continuous production, the feed rate of methanol is controlled to be 16.24ml / min, the feed rate of palm oil is controlled to be 48.91ml / min, and the residence time is 60min. The mixture after reaction is centrifuged and stratified, and the yellow transparent liquid biodiesel is obtained by vacuum distillation. The biodiesel yield is calculated to be 92.4% based on the product ratio.

[0123] Preparation Example 15

[0124] The preparation method is the same as that of Preparation Example 1.

[0125] In this embodiment, the molar ratio of methanol to palm oil is 8:1 (methanol pre-feeding amount is 770g, palm oil pre-feeding amount is 2700g), the catalyst is KNO3 / Al2O3, the pre-feeding amount is 2.0% (54g) of the mass of palm oil, the reaction pressure is 0.9MPa, the reaction temperature is 85°C, the specifications and dimensions of the venturi injector are: inlet section opening inner diameter: nozzle inner diameter: chamber closing inner diameter: mixing section length: diffusion section length = 38:3:4:140:1200, the opening angle of the diffusion section is 14°, and the fluid linear velocity at the nozzle of the venturi injector during the reaction is 115m / s. In continuous production, the feed rate of methanol is controlled to be 16.24ml / min, the feed rate of palm oil is controlled to be 48.91ml / min, and the residence time is 60min. The mixture after the reaction was centrifuged and stratified, and then distilled under reduced pressure to obtain yellow transparent liquid biodiesel. The yield of biodiesel was calculated to be 94.2% based on the ratio of the products taken.

[0126] Preparation Example 16

[0127] The preparation method is the same as that of Preparation Example 1.

[0128] In this embodiment, the molar ratio of methanol to palm oil is 10:1 (methanol pre-feeding amount is 853g, palm oil pre-feeding amount is 2400g), the catalyst is KF / Al2O3, the pre-feeding amount is 1.8% (43.2g) of the mass of palm oil, the reaction pressure is 0.6MPa, the reaction temperature is 65°C, the specifications and dimensions of the venturi injector are: inlet section opening inner diameter: nozzle inner diameter: chamber closing inner diameter: mixing section length: diffusion section length = 38:3:4:140:1200, the opening angle of the diffusion section is 14°, and the fluid linear velocity at the nozzle of the venturi injector during the reaction is 115m / s. In the continuous production, the feed rate of methanol is controlled to be 18.0ml / min, the feed rate of palm oil is controlled to be 43.48ml / min, and the residence time is 60min. The mixture after the reaction was centrifuged and stratified, and then distilled under reduced pressure to obtain yellow transparent liquid biodiesel. The yield of biodiesel was calculated to be 90.1% based on the proportion of the products.

[0129] Preparation Example 17

[0130] The preparation method is the same as that of Preparation Example 1.

[0131] In this embodiment, the molar ratio of methanol to palm oil is 6:1 (methanol pre-feeding amount is 280g, palm oil pre-feeding amount is 2700g), the catalyst is KOH / Al2O3, the pre-feeding amount is 2.5% (67.5g) of the mass of palm oil, the reaction pressure is 0.8MPa, the reaction temperature is 75°C, the specifications and dimensions of the venturi injector are: inlet section opening inner diameter: nozzle inner diameter: chamber closing inner diameter: mixing section length: diffusion section length = 38:3:4:140:1200, the opening angle of the diffusion section is 14°, and the fluid linear velocity at the nozzle of the venturi injector during the reaction is 115m / s. In continuous production, the feed rate of methanol is controlled to be 12.24ml / min, the feed rate of palm oil is controlled to be 48.91ml / min, and the residence time is 60min. The mixture after the reaction was centrifuged and stratified, and then distilled under reduced pressure to obtain yellow transparent liquid biodiesel. The yield of biodiesel was calculated to be 93.6% based on the ratio of the products taken.

[0132] Preparation Example 18

[0133] The preparation method is the same as that of Preparation Example 1.

[0134] In this embodiment, the molar ratio of methanol to palm oil is 12:1 (methanol pre-feeding amount is 1024g, palm oil pre-feeding amount is 2400g), the catalyst is K2CO3 / Al2O3, the pre-feeding amount is 3.5% (84g) of the mass of palm oil, the reaction pressure is 1MPa, the reaction temperature is 95°C, the specifications and dimensions of the venturi injector are: inlet section opening inner diameter: nozzle inner diameter: chamber closing inner diameter: mixing section length: diffusion section length = 38:3:4:140:1200, the opening angle of the diffusion section is 14°, and the fluid linear velocity at the nozzle of the venturi injector during the reaction is 115m / s. In continuous production, the feed rate of methanol is controlled to be 21.6ml / min, the feed rate of palm oil is controlled to be 43.48ml / min, and the residence time is 60min. The reaction mixture was centrifuged and stratified, and then distilled under reduced pressure to obtain yellow transparent liquid biodiesel. The biodiesel yield was calculated to be 92.5% based on the ratio of the products.

[0135] Preparation Example 18

[0136] The preparation method is the same as that of Preparation Example 1.

[0137] In this embodiment, the molar ratio of methanol to palm oil is 3:1 (methanol pre-feeding amount is 290g, palm oil pre-feeding amount is 2700g), the catalyst is K2CO3 / Al2O3, the pre-feeding amount is 2.2% (59.4g) of the mass of palm oil, the reaction pressure is 1.4MPa, the reaction temperature is 105°C, the specifications and dimensions of the venturi injector are: inlet section opening inner diameter: nozzle inner diameter: chamber closing inner diameter: mixing section length: diffusion section length = 38:3:4:140:1200, the opening angle of the diffusion section is 14°, and the fluid linear velocity at the nozzle of the venturi injector during the reaction is 115m / s. In continuous production, the feed rate of methanol is controlled to be 6.12ml / min, the feed rate of palm oil is controlled to be 48.91ml / min, and the residence time is 60min. The mixture after the reaction was centrifuged and stratified, and then distilled under reduced pressure to obtain yellow transparent liquid biodiesel. The yield of biodiesel was calculated to be 85.4% based on the proportion of the products taken.

[0138] Comparative Example

[0139] Into a 2L autoclave, 1200g of deacidified palm oil, 340g of anhydrous methanol, and 54g of KF / Al2O3 catalyst powder were added in sequence, pressurized with nitrogen at 1MPa, replaced three times, stirring and heating were started, the speed was adjusted to 750 rpm, the temperature was raised to 85°C, and the reaction pressure was maintained at 1MPa by a pressure regulator. This was marked as the start of the reaction and the reaction time was 5h.

[0140] The mixture after the reaction was centrifuged and stratified, and then distilled under reduced pressure to obtain yellow transparent liquid biodiesel. The yield of biodiesel was calculated to be 35.2% based on the ratio of the products taken.

Claims

1. A continuous production method for biodiesel, characterized in that: The continuous production method uses methanol and palm oil as raw materials, solid alkali as catalyst, and adopts a jet loop reactor for continuous production; the jet loop reactor comprises a reactor, a circulation pump, a heat exchanger and a venturi ejector; the jet loop reactor also comprises a filter tube; the filter tube comprises an inner tube formed by a tubular filter element and an outer tube sleeved on the outside, and the outer tube is sealed and connected to both ends of the inner tube; the bottom of the reactor is connected to the heat exchanger through a circulation pump; the heat exchanger is connected to the venturi ejector arranged at the top of the reactor through the inner tube of the filter tube and a feed pipe in turn; the venturi ejector comprises a filter tube connected in turn The inlet section, nozzle, mixing section and diffusion section are connected, wherein the inlet section and the nozzle are in a tapered tubular shape, and the outer periphery of the inlet section and the nozzle is provided with a tapered annular air chamber, which is connected with the mixing section, and the air chamber is connected with the air inlet arranged on the upper part of the reactor through a gas circulation pipe; the diffusion section is in a gradually expanding tubular shape; the feed pipe is provided with a feed port; the outer tube of the filter element tube is provided with a discharge port; the feed port includes a methanol feed port and a palm oil feed port; the upper part of the reactor is also provided with a catalyst feed port; the specifications and dimensions of the Venturi injector are: the inner diameter of the inlet section opening: the inner diameter of the nozzle: the inner diameter of the air chamber closing: the length of the mixing section: the length of the diffusion section = 38: (1.5-4): (2-6): (90-190): (800-1600), the opening angle of the diffusion section is 8-20°; the continuous production method is as follows: methanol, palm oil and catalyst are pre-charged in a reactor, nitrogen is introduced through the air inlet, and the reaction pressure in the injection loop reactor is maintained; and during continuous production, methanol and palm oil are continuously fed through the feed port, and the materials enter the reactor through the venturi ejector for reaction, and then enter the heat exchanger from the bottom through the circulation pump, and pass through the inner tube of the filter tube. A part of the material containing solid alkali enters the venturi ejector through the feed pipe, and the other part enters the outer tube of the filter tube after filtration, and is discharged from the outlet. The material port is continuously produced; the production amount of the material outlet is equal to the feed amount of raw material methanol and palm oil, and the reaction residence time is controlled by adjusting the feed amount; and the pressure in the reaction system is maintained unchanged; during continuous production, the reaction residence time is controlled to be 30-90min by adjusting the feed amount of raw material methanol and palm oil; during continuous production, the fluid linear velocity at the nozzle of the venturi injector is controlled to be 90-130m / s; the methanol and palm oil are fed in a molar ratio of (2-13):1; during pre-feeding, the amount of the catalyst added is 1-4% of the mass of the palm oil; during continuous production, the reaction temperature is controlled to be 60-110°C, and the reaction pressure is controlled to be 0.5-1.5MPa.

2. The continuous production method according to claim 1, characterized in that: The specifications and dimensions of the Venturi ejector are: inlet section opening inner diameter: nozzle inner diameter: air chamber closing inner diameter: mixing section length: diffusion section length = 38:3:4: (140~170): (1200~1400), and the opening angle of the diffusion section is 14~18°.

3. The continuous production method according to claim 1 or 2, characterized in that: The methanol and palm oil are fed in a molar ratio of 8:1; during pre-feeding, the amount of the catalyst added is 2% of the mass of the palm oil; during continuous production, the reaction temperature is controlled to be 85°C, the reaction pressure is 0.9MPa, and the fluid linear velocity at the venturi injector nozzle is 115m / s.

4. The continuous production method according to claim 1 or 2, characterized in that: The solid alkali adopts KF / MgO, KF / CaO, KNO3 / Al2O3, KOH / Al2O3, KF / Al2O3 or K2CO3 / Al2O3; the KF / MgO uses MgO as a carrier, and KF with a mass of 60% of MgO is loaded thereon; the KNO3 / Al2O3 uses Al2O3 as a carrier, and KNO3 with a mass of 20% of Al2O3 is loaded thereon; the KOH / Al2O3 uses Al2O3 as a carrier, and KOH with a mass of 15% of Al2O3 is loaded thereon; the KF / CaO uses CaO as a carrier, and KF with a mass of 14% of CaO is loaded thereon; the KF / Al2O3 uses Al2O3 as a carrier, and KF with a mass of 15% of Al2O3 is loaded thereon; the K2CO3 / Al2O3 uses Al2O3 as a carrier, and K2CO3 with a mass of 20% of Al2O3 is loaded thereon.

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