CN102108319A - Continuous system and method for preparing biodiesel - Google Patents

Abstract

The invention relates to a continuous system and a method for preparing biodiesel, wherein the continuous method for preparing the biodiesel comprises the following steps: pressurizing and heating the liquid alcohol to a subcritical state or a high-pressure liquid state; (b) utilizing a continuous extraction module to perform continuous extraction, wherein the continuous extraction module is provided with a plurality of extraction tanks, and the extraction tanks are used for receiving subcritical or high-pressure liquid alcohol and extracting the oil raw material in the extraction tanks to obtain an extraction product; (c) performing transesterification on the extraction product to obtain a transesterification product; and (d) separating the transesterification product to obtain the biodiesel. The continuous system and the method for preparing the biodiesel utilize subcritical or high-pressure liquid alcohols to extract grease and use supercritical alcohols to perform transesterification to prepare the biodiesel, and the extraction is carried out by the continuous extraction module and the method, so that the process can be simplified, and the labor and the energy can be saved because the same alcohols are used for extraction and transesterification.

Description

Continuous system and method for producing biodiesel

technical field

The present invention relates to a system and method for preparing biodiesel, in particular, relates to a continuous system and method for preparing biodiesel.

Background technique

Traditional biodiesel (biodiesel) is produced by alkaline process or acid process, but due to the need to use acid-base catalysts or reactants, it often causes troubles in the purification and recycling of the latter product. At present, legal biodiesel plants are all first-generation technology and mainly based on American regulations. The esterification reaction takes a long time and the conversion rate is not high. Due to the use of acid and alkali raw materials, waste liquid treatment is a big problem, and it contains many impurities. (such as saponification), must be rectified to reach industrial standards, and the cost is relatively high.

At present, there are also several techniques for improving the traditional biodiesel method, and the two-stage transesterification preparation technology is one of them, but there are many shortcomings; in addition, although biotransesterification has the advantages of direct conversion of free fatty acids and easy separation of glycerin, However, due to the use of biological catalysts, the cost is high and the reaction rate is slow; as for the solid-state catalyst method, it is still mostly discussed in the literature and has not yet been industrialized.

U.S. Patent No. 6,211,390 B1, the patent title is "Method for producing fatty acid" (fatty acid ester manufacturing method), which discloses a method for preparing biodiesel by supercritical extraction. The patent is to use triglyceride-rich raw materials , transesterification reaction with alcohols under the action of alkaline catalysts, the fatty acid esters generated and unreacted excess alcohol reactants are then extracted and separated by near or supercritical fluids under the action of heterogeneous catalysts to obtain high pure biodiesel. The disadvantage of this patent is that it has limitations on the production of biodiesel raw materials, and it cannot be widely used in oil sources containing water or free fatty acids; moreover, the reactant methanol needs to be excessive in the process of transesterification, and it is carried out with supercritical fluid under the action of a heterogeneous catalyst Methanol extraction and separation may require a large amount of energy to achieve the purpose of high separation and purification.

China Taiwan Patent Announcement No. 466271 patent, titled "method for producing alkyl esters of fatty acids from oils and fats", discloses a method of transesterification in a supercritical lower alcohol state without the use of metal alkali catalysts or acid catalysts. Diesel method. This patent is to use free fatty acid-containing oil raw materials and low-carbon alcohols to react, and transesterify the triglycerides contained in oils and fats in the state of supercritical alcohols to produce alkyl esters of fatty acids. At the same time, because the reaction is carried out without using a metal alkali catalyst or an acid catalyst, there is no need to carry out the pretreatment step of esterifying free fatty acids, and no by-products of fatty acid soaps will be generated, so the production of the products can be omitted or simplified. Recycle the refining step. This patent is limited to the method of producing alkyl esters of fatty acids with supercritical methanol, and the raw material may be waste cooking oil or biomass oil.

China's "Journal of Applied Chemistry" Volume 23 No. 12 "Preparation of Biodiesel by Rapeseed and Supercritical Methanol In Situ Extraction-Transesterification Reaction" pointed out that: direct use of rapeseed and supercritical methanol to prepare biodiesel can be Combining supercritical extraction and supercritical transesterification, on the one hand, supercritical extraction is used to increase the extraction rate of oil in rapeseed; on the other hand, supercritical extraction and supercritical transesterification are carried out simultaneously in the same reactor, which can The procedure of extracting oil is omitted, and the production cost of biodiesel is reduced. Regarding the supercritical extraction of vegetable oils, the current research is more on the supercritical _CO2 extraction method. This document uses the supercritical methanol method to extract the oil and combines the supercritical extraction and supercritical transesterification to prepare biodiesel. None of the studies have been reported in the literature so far. However, the operating temperature and pressure conditions for optimal extraction and transesterification are different, and performing supercritical extraction and supercritical transesterification simultaneously in the same reactor is a batch operation, which cannot achieve a continuous process.

Therefore, it is necessary to provide an innovative and progressive continuous system and method for preparing biodiesel to solve the above problems.

Contents of the invention

In order to solve the above technical problems, the object of the present invention is to provide a continuous system and method for preparing biodiesel, through continuous extraction and transesterification of supercritical alcohols, to prepare biodiesel, which has the characteristics of simple process and low cost .

To achieve the above object, the present invention at first provides a continuous system for preparing biodiesel, comprising:

A liquid alcohol storage tank for storing liquid alcohol;

A continuous extraction module has a plurality of extraction tanks, the extraction tanks are used to receive liquid alcohol, and extract the oil and fat raw materials in the extraction tanks to obtain extraction products and achieve continuous extraction;

A tubular transesterification reactor for receiving the extracted product for transesterification to obtain a transesterification product; and

A first gas-liquid separation tank for separating transesterification products to obtain biodiesel.

In the above continuous system, preferably, the continuous system further includes a first liquid pump and a first preheater for pressurizing and heating the liquid alcohol to a subcritical state or a high pressure liquid state.

In the above-mentioned continuous system, preferably, the continuous extraction module includes three extraction tanks, which are used to perform alternate operations of filling, extracting and discharging oil and fat raw materials respectively.

In the above continuous system, preferably, the oil raw material is a raw material plant rich in triglyceride, and the extraction product is triglyceride and alcohol.

In the above continuous system, preferably, the continuous system further includes a second preheater for heating the extraction product. More preferably, the continuous system further includes a check valve disposed between the second preheater and the continuous extraction module.

In the above continuous system, preferably, the tubular transesterification reactor is maintained at a supercritical operating condition.

In the above continuous system, preferably, the first gas-liquid separation tank is used to separate the transesterification product into fatty acid esters, glycerol in liquid phase, and alcohols in gas phase. More preferably, the continuous system further includes a condenser, which is arranged between the first gas-liquid separation tank and the liquid alcohol storage tank, and is used to condense the alcohols in the gas phase into the liquid alcohol storage tank.

In the above continuous system, preferably, the continuous system further comprises a _CO2 storage tank, a first condenser, a second liquid pump and a second preheater, wherein the _CO2 storage tank is used to store CO ₂ , the first condenser is used to condense CO ₂ into a liquid state, the second liquid pump feeds liquid CO ₂ into the second preheater, and the second preheater is used to heat the liquid CO ₂ and the extraction product.

In the above continuous system, preferably, the tubular transesterification reactor is used to receive the extraction product and CO ₂ for transesterification to obtain the transesterification product; the first gas-liquid separation tank is used to The transesterification products are separated into fatty acid esters and glycerol in the liquid phase, and alcohols and CO ₂ in the gas phase.

In the above continuous system, preferably, the continuous system further includes a second gas-liquid separation tank for receiving alcohols and CO ₂ in the gas phase and separating them into alcohols in the liquid phase and CO ₂ in the gas phase, and the liquid phase The alcohols are introduced into the liquid alcohol storage tank.

In the above continuous system, preferably, the continuous system further includes a second condenser, arranged between the second gas-liquid separation tank and the _CO2 storage tank, to condense _CO2 in the gaseous phase Introduce to the _CO2 storage tank.

The present invention also provides a continuous method for preparing biodiesel, comprising the following steps:

(a) Pressurizing and heating liquid alcohol to a subcritical or high-pressure liquid state;

(b) Continuous extraction is carried out by using a continuous extraction module, wherein the continuous extraction module has a plurality of extraction tanks, and the extraction tanks are used to receive subcritical or high-pressure liquid alcohol, and extract the oil and fat raw materials in the extraction tanks , to obtain the extracted product;

(c) subjecting the extracted product to transesterification to obtain a transesterification product; and

(d) separating the transesterification product to obtain biodiesel.

In the above-mentioned continuous method, preferably, in step (b), the continuous extraction module includes three extraction tanks for alternate operations of filling, extracting and discharging oil and fat raw materials respectively.

In the above continuous method, preferably, in step (b), the oil raw material is a raw material plant rich in triglyceride, and the extraction product is triglyceride and alcohol.

In the above continuous method, preferably, after step (b), the method further includes a heating step for heating the extracted product.

In the above-mentioned continuous method, preferably, in step (c), the transesterification is performed under supercritical operating conditions.

In the above continuous method, preferably, in step (d), the transesterification product is separated into fatty acid esters, glycerol in the liquid phase, and alcohols in the gas phase.

In the above continuous method, preferably, after the step (d), the method further includes a condensation step for condensing the alcohols in the gas phase.

In the above continuous method, preferably, before step (c), the method further includes a step of providing CO ₂ , which includes a step of condensing CO ₂ into a liquid state, a step of pressurizing liquid CO ₂ and heating the liquid CO ₂ And the step of extracting the product.

In the above continuous method, preferably, in step (c), the extracted product and CO ₂ are transesterified to obtain a transesterified product.

In the above-mentioned continuous method, preferably, in step (d), a first gas-liquid separation step is included to separate the transesterification product into fatty acid esters, glycerol in the liquid phase, and alcohols and CO in the gas phase. ₂ .

In the above continuous method, preferably, in step (d), the method further includes a second gas-liquid separation step for receiving gas phase alcohols and CO ₂ and separating them into liquid phase alcohols and gas phase CO ₂ .

In the above continuous method, preferably, after the second gas-liquid separation step, a condensation step is further included to condense the CO ₂ in the gas phase.

The invention provides a continuous system for preparing biodiesel, comprising: a liquid alcohol storage tank, a continuous extraction module, a tubular transesterification reactor and a first gas-liquid separation tank. The liquid alcohol storage tank is used for storing liquid alcohol. The continuous extraction module has a plurality of extraction tanks, at least one of which is used to receive liquid alcohol and extract the oil and fat raw materials in the extraction tank to obtain extraction products and achieve continuous extraction. The tubular transesterification reactor is used to receive the extracted product for transesterification to obtain a transesterification product. The first gas-liquid separation tank is used to separate transesterification products to obtain biodiesel.

The present invention also provides a continuous method for preparing biodiesel, comprising the following steps: (a) pressurizing and heating liquid alcohol to a subcritical or high-pressure liquid state; (b) using a continuous extraction module for continuous extraction, wherein the The continuous extraction module has a plurality of extraction tanks, which are used to receive subcritical or high-pressure liquid alcohol, and extract the oil and fat raw materials in the extraction tanks to obtain extraction products; (c) transesterify the extraction products to obtain a transesterification product; and (d) separating the transesterification product to obtain biodiesel.

The continuous system and method for preparing biodiesel of the present invention utilizes subcritical state or high-pressure liquid alcohols to extract grease and supercritical alcohols to transesterify to prepare biodiesel, and extracts through continuous extraction modules and methods, and then performs supercritical Alcohol transesterification, the same alcohol is used in the system and method to perform extraction and transesterification procedures at the same time, which can simplify the process and save manpower and energy.

Description of drawings

Fig. 1 shows the schematic diagram of the continuous system for preparing biodiesel provided by the embodiment of the present invention 1;

Fig. 2 shows a schematic diagram of a continuous system for preparing biodiesel provided by Example 2 of the present invention.

Description of main component symbols:

Embodiment 1 of the present invention is a continuous system 10 for preparing biodiesel; a liquid alcohol storage tank 11;

The first liquid pump, 12; the first preheater, 13; the continuous extraction module, 14; the check valve 15;

The second preheater, 16; the tubular transesterification reactor, 17; the first gas-liquid separation tank, 18;

Condenser, 19; Continuous system for preparing biodiesel in Example 2 of the present invention, 30;

Liquid alcohol storage tank, 31; first liquid pump, 32; first preheater, 33;

Continuous extraction module, 34; check valve, 35; CO _storage tank, 36; first condenser, 37;

The second liquid pump, 38; the second preheater, 39; the tubular transesterification reactor, 40;

The first gas-liquid separation tank, 41; the second gas-liquid separation tank, 42; the second condenser, 43;

The first extraction tank, 141; the second extraction tank, 142; the third extraction tank, 143;

The first extraction tank, 341; the second extraction tank, 342; the third extraction tank, 343.

Detailed ways

Example 1

Referring to FIG. 1 , it shows a schematic diagram of a continuous system for preparing biodiesel provided by Example 1 of the present invention. The following uses FIG. 1 to illustrate the continuous system and method for preparing biodiesel provided by Example 1 of the present invention. The continuous system 10 for preparing biodiesel provided by Example 1 of the present invention includes: a liquid alcohol storage tank 11 , a continuous extraction module 14 , a tubular transesterification reactor 17 and a first gas-liquid separation tank 18 . The liquid alcohol storage tank 11 is used for storing liquid alcohol.

In this embodiment, the continuous system 10 for preparing biodiesel of the present invention further includes a first liquid pump 12 and a first preheater 13, which are used to pressurize and heat the liquid alcohol to a subcritical or high-pressure liquid state . Among them, the subcritical state refers to the temperature maintained below the critical temperature of 240°C and the pressure above the critical pressure of 80atm; the high-pressure liquid state refers to the temperature maintained below the critical temperature of 240°C and the pressure below the critical pressure of 80atm. In addition, in this embodiment, the liquid alcohol may be a low-carbon alcohol with 1-5 carbons.

Subcritical or high-pressure liquid alcohol is introduced into the continuous extraction module 14 . The continuous extraction module 14 has a plurality of extraction tanks 141 , 142 , 143 , at least one of which is used to receive liquid alcohol and extract the oil in the extraction tank to obtain extraction products and achieve continuous extraction. In this embodiment, the continuous extraction module 14 includes three extraction tanks 141 , 142 , 143 for alternate operations of filling, extracting and discharging the oil and fat material. Preferably, the extraction tanks are high-pressure extraction tanks.

For example, if the first extraction tank 141 is filled with oil and fat material, the second extraction tank 142 can be used for extraction. At this time, the liquid alcohol in the subcritical state or high-pressure liquid state is introduced into the second extraction tank 142 for extraction. The third extraction tank 143 can carry out discharge operation. After the second extraction tank 142 is extracted, since the first extraction tank 141 is filled with the oil raw material, subcritical or high-pressure liquid liquid alcohol can be introduced into the first extraction tank 141 for extraction, and the third extraction tank 143 can carry out the oil raw material Loading work. Therefore, the three extraction tanks 141, 142, 143 can respectively carry out the alternate operation of oil raw material filling, extraction and discharge, so that the extraction operation is continuous and uninterrupted.

In this embodiment, the oil raw material is a raw material plant rich in triglycerides, such as leprosy seeds crushed to a particle size of 1-5mm, and the liquid alcohol is selected from methanol, because subcritical methanol has excellent Diffusion, mass transfer and ability to dissolve triglycerides, the extraction time can last for about 0.5-2hr. Therefore, oil extraction with subcritical/high-pressure liquid alcohol has the advantages of high yield, short time, and easy control of optimal extraction conditions such as pressure and temperature. If the oil-containing vegetable raw material is rich in cellulose, the cellulose will not be changed under high pressure and heated below 150°C; under high pressure and heated above 150°C, the cellulose will be dehydrated and coked, but it is not suitable for the extraction and subsequent transformation of triglycerides. Esterification has no effect. Therefore, the continuous system 10 for preparing biodiesel provided by the present invention can use a wide range of raw materials, which can contain a large amount of water, triglycerides and free fatty acids, and the raw materials can be processed without being completely dried.

In this embodiment, the extracted products through the extraction tank are triglyceride and alcohol. The continuous system 10 for preparing biodiesel provided by the present invention further includes a check valve 15 and a second preheater 16 . The check valve 15 is disposed between the second preheater 16 and the continuous extraction module 14 . The second preheater 16 is used to heat the extraction product, so that the temperature of the extraction product is higher than the critical temperature of methanol.

The tubular transesterification reactor 17 is used to receive the extracted product for transesterification to obtain a transesterification product. In this embodiment, the tubular transesterification reactor 17 is maintained at a supercritical operating condition for supercritical methanol transesterification reaction. The optimum transesterification condition can be as follows: the operating temperature is controlled at 240°C- 320°C, the operating pressure is controlled at 100-250atm. Transesterification products include: fatty acid ester (biodiesel), glycerin (by-product), aqueous solution and unreacted methanol. The continuous system 10 for preparing biodiesel provided by the present invention uses supercritical alcohol to perform transesterification to prepare biodiesel, with high conversion rate, short reaction time, no acid-base catalyst, and no acid-base reprocessing problem.

The first gas-liquid separation tank 18 is used to separate transesterification products to obtain biodiesel. The first gas-liquid separation tank 18 separates transesterification products into fatty acid esters (biodiesel) in liquid phase, glycerin to the bottom of the tank, and alcohols in gas phase to the top of the tank. The continuous system 10 for preparing biodiesel provided by the present invention further includes a condenser 19, which is arranged between the first gas-liquid separation tank 18 and the liquid alcohol storage tank 11, and is used to condense the alcohols in the gas phase into the liquid The alcohol storage tank 11 is recycled.

The continuous system 10 for preparing biodiesel provided in Example 1 of the present invention utilizes subcritical or high-pressure liquid alcohols to extract oil and supercritical alcohols to transesterify to prepare biodiesel, and extracts through continuous extraction modules and methods, Then transesterification of supercritical alcohols is carried out, and the same alcohols are used for extraction and transesterification procedures in the system and method at the same time, which can simplify the process and save manpower and energy.

Example 2

Referring to FIG. 2 , it shows a schematic diagram of a continuous system for preparing biodiesel provided by Example 2 of the present invention. The continuous system 30 for preparing biodiesel provided by Embodiment 2 of the present invention includes: a liquid alcohol storage tank 31, a first liquid pump 32, a first preheater 33, a continuous extraction module 34, and a check valve 35, a CO _storage tank 36, a first condenser 37, a second liquid pump 38, a second preheater 39, a tubular transesterification reactor 40, a first gas-liquid separation tank 41, A second gas-liquid separation tank 42 and a second condenser 43 .

The liquid alcohol storage tank 31, the first liquid pump 32, the first preheater 33, the continuous extraction module 34 and the check valve 35 of the continuous system 30 for preparing biodiesel provided by Embodiment 2 of the present invention are the same as those in the embodiment of the present invention The continuous system 10 for preparing biodiesel provided in 1 is the same, and the continuous extraction module 34 has a first extraction tank 341, a second extraction tank 342 and a third extraction tank 343, which will not be described again.

In this embodiment, before the extraction product is introduced into the second preheater 39, an appropriate amount of CO ₂ is added. Wherein the CO ₂ storage tank 36 is used to store CO ₂ , the first condenser 37 is used to condense CO ₂ into a liquid state, the second liquid pump 38 adds liquid CO ₂ to the second preheater 39, and the second The preheater 39 receives the liquid CO ₂ and the extraction product for heating the liquid CO ₂ and the extraction product.

The tubular transesterification reactor 40 is used to receive the extracted product and CO ₂ for transesterification to obtain a transesterification product. In the present embodiment, the tubular transesterification reactor 40 is also maintained at supercritical operating conditions to carry out supercritical methanol transesterification reaction, but the temperature and pressure of the transesterification can be reduced due to the addition of _CO , so as to Save electricity. And due to the addition of CO ₂ , transesterification products include: fatty acid ester (biodiesel), glycerin (by-product), aqueous solution, unreacted methanol and CO ₂ .

The first gas-liquid separation tank 41 is used to separate transesterification products into liquid phase fatty acid esters, glycerin, and gas phase alcohols and CO ₂ . The second gas-liquid separation tank 42 is used to receive gas phase alcohols and CO ₂ and separate them into liquid phase alcohols and gas phase CO ₂ . The liquid phase alcohols are introduced into the liquid alcohol storage tank 31 for recycling. The second condenser 43 is disposed between the second gas-liquid separation tank 42 and the CO ₂ storage tank 36 for condensing CO ₂ in gaseous phase into the CO ₂ storage tank 36 for recycling.

Therefore, the continuous system and method for preparing biodiesel provided by the present invention utilizes subcritical or high-pressure liquid alcohols to extract oil and supercritical alcohols to transesterify to prepare biodiesel, and extract through continuous extraction modules and methods, Then transesterification of supercritical alcohols is carried out, and the same alcohols are used for extraction and transesterification procedures in the system and method at the same time, which can simplify the process and save manpower and energy.

The above-mentioned embodiments are only to illustrate the principles and effects of the present invention, but not to limit the present invention. Therefore, those skilled in the art can modify and change the above embodiments without departing from the spirit of the present invention. The scope of rights of the present invention should be listed in the following claims.

Claims (26)

1. A continuous system for preparing biodiesel, comprising: A liquid alcohol storage tank for storing liquid alcohol; A continuous extraction module has a plurality of extraction tanks, the extraction tanks are used to receive liquid alcohol, and extract the oil and fat raw materials in the extraction tanks to obtain extraction products and achieve continuous extraction; A tubular transesterification reactor for receiving the extracted product for transesterification to obtain a transesterification product; and A first gas-liquid separation tank for separating transesterification products to obtain biodiesel. 2. The continuous system according to claim 1, wherein the continuous system further comprises a first liquid pump and a first preheater for pressurizing and heating the liquid alcohol to subcritical or high pressure liquid. 3. The continuous system according to claim 1, wherein the continuous extraction module comprises three extraction tanks for alternate operations of filling, extracting and discharging the oil and fat raw materials respectively. 4. The continuous system according to claim 3, wherein the oil raw material is a raw material plant rich in triglyceride, and the extraction product is triglyceride and alcohol. 5. The continuous system as claimed in claim 1, wherein the continuous system further comprises a second preheater for heating the extraction product. 6. The continuous system according to claim 5, wherein the continuous system further comprises a check valve disposed between the second preheater and the continuous extraction module. 7. The continuous system of claim 1, wherein the tubular transesterification reactor is maintained at supercritical operating conditions. 8. The continuous system according to claim 1, wherein the first gas-liquid separation tank is used to separate the transesterification product into fatty acid esters, glycerol in liquid phase, and alcohols in gas phase. 9. The continuous system as claimed in claim 8, wherein the continuous system further comprises a condenser, which is arranged between the first gas-liquid separation tank and the liquid alcohol storage tank to convert the gas phase The alcohols are condensed and introduced into the liquid alcohol storage tank. 10. The continuous system of claim 1, wherein the continuous system further comprises a CO ₂ storage tank, a first condenser, a second liquid pump, and a second preheater, wherein the CO ₂ The storage tank is used to store CO ₂ , the first condenser is used to condense CO ₂ into a liquid state, the second liquid pump is used to feed liquid CO ₂ into the second preheater, and the second preheater is used to convert liquid CO ₂ and The extracted product is heated. 11. The continuous system according to claim 10, wherein the tubular transesterification reactor is used to receive the extracted product and CO ₂ for transesterification to obtain a transesterification product. 12 . The continuous system according to claim 11 , wherein the first gas-liquid separation tank is used to separate the transesterification product into fatty acid esters, glycerol in liquid phase, and alcohols and CO ₂ in gas phase. 13 . 13. The continuous system as claimed in claim 12, wherein the continuous system further comprises a second gas-liquid separation tank for receiving gas phase alcohols and CO ₂ and separating them into liquid phase alcohols and gas phase CO ₂ and alcohols in the liquid phase are introduced into the liquid alcohol storage tank. 14. The continuous system as claimed in claim 13, wherein the continuous system further comprises a second condenser, arranged between the second gas-liquid separation tank and the _CO2 storage tank, in order to The CO ₂ condensed in the gas phase is directed to the CO ₂ storage tank. 15. A continuous method for preparing biodiesel comprising the steps of: a. Pressurize and heat liquid alcohol to a subcritical state or a high-pressure liquid state; b. Using a continuous extraction module for continuous extraction, wherein the continuous extraction module has a plurality of extraction tanks, the extraction tanks are used to receive subcritical or high-pressure liquid alcohol, and extract the oil and fat raw materials in the extraction tanks, to obtain the extracted product; c. Transesterifying the extracted product to obtain a transesterified product; and d. Separating the transesterification product to obtain biodiesel. 16. The continuous method as claimed in claim 15, wherein, in step b, the continuous extraction module comprises three extraction tanks for alternate operations of filling, extracting and discharging oil and fat raw materials respectively. 17. The continuous method according to claim 16, wherein, in step b, the oil raw material is a raw material plant rich in triglyceride, and the extraction product is triglyceride and alcohol. 18. The continuous method as claimed in claim 15, wherein, after step b, the method further comprises a heating step for heating the extracted product. 19. The continuous method as claimed in claim 15, wherein, in step c, the transesterification is carried out under supercritical operating conditions. 20. The continuous method as claimed in claim 15, wherein, in step d, the transesterification product is separated into fatty acid esters, glycerol in the liquid phase, and alcohols in the gas phase. 21. The continuous method as claimed in claim 20, wherein, after step d, the method further comprises a condensation step for condensing the alcohol in the vapor phase. 22. The continuous method of claim 15, wherein, before step c, the method further comprises a step of providing CO ₂ , which includes the step of condensing CO ₂ into a liquid state, the step of pressurizing liquid CO ₂ and heating Liquid CO ₂ and the step of extracting the product. 23. The continuous process as claimed in claim 22, wherein, in step c, the extracted product and _CO2 are transesterified to obtain a transesterified product. 24. The continuous method as claimed in claim 23, wherein, in step d, a first gas-liquid separation step is included to separate the transesterification product as fatty acid ester, glycerol in liquid phase, and alcohol in gas phase class and CO ₂ . 25. The continuous method as claimed in claim 24, wherein, in step d, the method further comprises a second gas-liquid separation step for receiving alcohols and CO ₂ in the gas phase and separating them into alcohols in the liquid phase and gaseous CO ₂ . 26. The continuous method as claimed in claim 25, further comprising a condensation step after the second gas-liquid separation step to condense the CO ₂ in the gaseous phase.

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