JP2006312749A - Manufacturing apparatus of fuel fatty acid ester from oil cake - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing apparatus of fuel fatty acid ester, capable of producing fatty acid ester from oil cake generated in a deoxidation step for refining oil and fat. <P>SOLUTION: The manufacturing apparatus comprises (a) a decomposition reaction means A heating the oil cake, to which sulfuric acid is previously added to make pH 5 or lower, to 50-120°C, agitating and mixing to decompose, (b) a separating means B separating dark oil composed mainly of fatty acid and oil and fat generated by decomposition reaction, (c) a washing means C washing the separated dark oil, and (d) a reacting mechanism D having a mixing means 3c for mixing the washed dark oil with a 1-5C lower alcohol of about 0.5-1.0 times of the dark oil, and a tubular reactor 4 fed with a mixture, which is mixed with the lower alcohol in the mixing means, at a liquid space velocity of about 0.08-0.13 l/min and performing esterification reaction at 200-350°C, 15-25 MPa and under a condition of supercritical state of the lower alcohol. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an apparatus for producing a fatty acid ester, and more specifically, fatty acid soap, oil and fat, moisture, and other impurities obtained by neutralizing and separating a free fatty acid with an alkali in a deoxidation process that is one of oil and fat purification processes. The present invention relates to an apparatus for producing a fatty acid ester for fuel from oil slag.

  For example, in the deoxidation process, which is one of the refining processes for vegetable oils and fats, free fatty acids, phospholipids and trace metals contained in crude oil are removed. Generally, free fatty acids are neutralized with an alkaline aqueous solution, A method of separating and removing fatty acid soap that is sparingly soluble in fats and oils is used.

  This fatty acid soap is separated together with moisture, fats and oils (oils and fats mainly derived from attached raw material fats and oils), and other impurities, and is called oil cake (deoxidized oil cake). This oil cake is also called alkaline foots or soap stock.

By the way, this oil cake usually contains 30 to 70% by weight of water, 20 to 60% by weight of fatty acid soap and fat and oil, and 10 to 50% by weight of other impurities (such as gum components). Then, the fatty acid soap in the oil cake is separated from other moisture together with fats and oils as fatty acids again by acid decomposition. In addition, the mixture of fatty acids and fats and oils separated by acid decomposition as described above is called dark oil, and usually 60 to 80% by weight of fatty acids and 40 to 20% by weight of fats and oils. Contains.
And this dark oil has been conventionally used as a raw material for fuels and crude fatty acids. However, in recent years, the use of higher added value is being sought.

  This invention is made | formed in view of this situation, The fatty-acid ester of the high-value-added fatty acid ester which can be manufactured from the oil cake generated in the deoxidation process which is one of the refinement | purification processes of fats and oils. An object is to provide a manufacturing apparatus.

In order to achieve the above object, an apparatus for producing a fatty acid ester for fuel according to the present invention (Claim 1) comprises:
In order to produce a fatty acid ester for fuel from an oil cake containing fatty acid soap, fats and oils, moisture, and other impurities, in which a free fatty acid is neutralized with an alkali and separated in a deoxidation step, which is one of the purification steps of fats and oils An apparatus for producing a fatty acid ester for fuel,
(a) It is constituted so that sulfuric acid can be added to the oil cake until at least the pH becomes 5 or less, and the oil cake with sulfuric acid added until the pH becomes 5 or less is heated to 50 to 120 ° C., and A decomposition reaction means for decomposing the oil cake, which is configured to be stirred and mixed;
(b) separation means for separating dark oil mainly composed of fatty acids and fats and oils generated by the decomposition reaction from the reaction liquid subjected to the decomposition reaction in the decomposition reaction means;
(c) washing means for washing the dark oil separated by the separation means with water;
(d) a mixing means for mixing the dark oil washed by the washing means with about 0.5 to 1.0 times the weight of the dark oil and a lower alcohol having 1 to 5 carbon atoms; and the mixing means A mixed liquid mixed with a lower alcohol is supplied under conditions of a liquid space velocity of about 0.08 to 0.13 1 / min, and the lower alcohol is supercritical within a temperature range of 200 to 350 ° C. and a pressure of 15 to 25 MPa. And a reaction mechanism unit including a tubular reactor for performing an esterification reaction under the condition to be in a state.

The apparatus for producing a fatty acid ester for fuel according to claim 2 comprises:
further,
(e) Distilling the reaction liquid in which the esterification reaction has been performed in the reaction mechanism unit, a low boiling point component containing alcohol and water as main components, and a high boiling point containing fatty acid, fatty acid ester, and high boiling point impurities as main components Distillation means to separate the components;
(f) an alcohol recovery means for recovering alcohol by distilling the low boiling point component;
(g) fatty acid removing means for separating and removing fatty acids contained in the high boiling point component by a neutralization reaction;
(h) a high boiling point impurity removing unit that distills a high boiling point component separated and removed by the fatty acid removing unit to remove a high boiling point impurity as a residue of the kettle;
(i) separating means for separating the fatty acid ester and glycerin in the high-boiling component from which the high-boiling-point impurities have been separated by distillation in the high-boiling-point impurity removing means, into a fatty acid ester and glycerin due to a difference in specific gravity. It is said.

  Further, in the apparatus for producing a fatty acid ester for fuel according to claim 3, the lower alcohol is in a supercritical state while the mixing means constituting the reaction mechanism unit mixes the dark oil and the lower alcohol in a liquid phase state. It is characterized by being comprised so that it can heat up even to the reaction temperature which becomes.

As described above, in the apparatus for producing a fatty acid ester for fuel according to the present invention (Claim 1), in the decomposition reaction means, sulfuric acid is added to the oil bottle until pH is at least 5 and heated to 50 to 120 ° C. After the decomposition reaction is carried out by stirring and mixing, dark oil mainly containing fatty acids and fats and oils (fats and fats derived mainly from attached raw material fats and oils) generated by the decomposition reaction from the reaction solution by the separating means The separated dark oil is washed with washing means, and the washed dark oil is mixed with the lower alcohol having a carbon number of 1 to 5 that is about 0.5 to 1.0 times the weight of the dark oil by mixing means. The mixture is mixed, and the esterification reaction is carried out under the condition that the alcohol is in a supercritical state in the tubular reactor constituting the reaction mechanism. It is possible to produce ether.
It should be noted that the reaction temperature was set in the range of 200 to 350 ° C. when the reaction temperature was less than 200 ° C., the progress of the esterification reaction was insufficient, and when the reaction temperature exceeded 350 ° C., the actual apparatus This is because it becomes difficult to secure a heat source, resulting in a significant increase in equipment costs, and thermal decomposition may occur depending on the type of fatty acid.

  The reason why the reaction pressure is in the range of 15 to 25 MPa is that the esterification reaction becomes insufficient when the reaction pressure is less than 15 MPa, and the equipment cost is significantly increased when the reaction pressure exceeds 25 MPa.

  More specifically, in the decomposition reaction means, sulfuric acid is added to the oil cake until the pH is at least 5, and the decomposition reaction is performed by stirring and mixing at 50 to 120 ° C. It becomes possible to decompose efficiently, and the resulting dark oil is mixed with alcohol, and the esterification reaction is carried out under the condition that the alcohol is in a supercritical state. It becomes possible.

  In addition, since the decomposition reaction means uses sulfuric acid as the acid to be added to the oil cake, it becomes possible to reliably decompose the oil cake without causing an increase in cost. It is possible to tighten.

  Moreover, the dark oil washed with water and about 0.5 to 1.0 times the weight of the dark oil and the lower alcohol having 1 to 5 carbon atoms are mixed by a mixing means, and the mixture is made into a tube type The alcohol is brought into a supercritical state while being supplied to the reactor and passing through the tubular reactor at a liquid space velocity of about 0.08 to 0.13 1 / min. Temperature: 200 to 350 ° C., pressure Since the esterification reaction is performed under the condition of 15 to 25 MPa, the alcohol in the critical state and the dark oil can be efficiently reacted, and the present invention can be effectively realized.

In addition, since the lower alcohol having 1 to 5 carbon atoms is used as the alcohol that contributes to the esterification reaction in the reaction mechanism section, the alcohol can be brought into a supercritical state under practical temperature and pressure conditions. It becomes possible, and this invention can be shown effectively.
Examples of the lower alcohol having 1 to 5 carbon atoms include methanol, ethanol, propanol, butanol, pentanol and the like.

  Further, since the separated dark oil is washed with water in the washing means and then subjected to esterification reaction, it becomes possible to produce a high purity fatty acid ester by removing water-soluble impurities in the dark oil. .

  Therefore, according to the present invention, it becomes possible to produce a high-purity fatty acid ester, and it is possible to produce a fatty acid ester that can be efficiently used as a fuel (light oil alternative fuel) from the oil cake. .

  In addition, as in claim 2, the apparatus for producing a fatty acid ester for fuel according to claim 1 further comprises (e) distilling the reaction solution subjected to the esterification reaction in the reaction mechanism section to obtain a low-boiling component and a high-boiling component. A distillation means for separating into boiling components; (f) an alcohol recovery means for collecting alcohol by distilling the low boiling components; and (g) a fatty acid removal means for separating and removing fatty acids contained in the high boiling components by a neutralization reaction. And (h) a high-boiling-point impurity removing means for removing a high-boiling-point impurity by distilling a high-boiling-point component from which the fatty acid has been separated and removed, and (i) a fatty acid ester in the high-boiling-point component from which the high-boiling point impurity has been separated. And a separation means for separating glycerin into fatty acid ester and glycerin due to a difference in specific gravity, it is possible to reliably and efficiently produce a high-purity fatty acid ester used as fuel from oil slag. The

  Further, as in the apparatus for producing a fatty acid ester for fuel according to claim 3, the mixing means raises the temperature to a reaction temperature at which the lower alcohol becomes a supercritical state while mixing the dark oil and the lower alcohol in a liquid phase state. When configured so that the esterification reaction can be performed, the esterification reaction can be performed more efficiently in the tubular reactor.

  Hereinafter, the features of the present invention will be described in more detail with reference to embodiments of the present invention.

  1-3 is a figure which shows the manufacturing apparatus used in order to manufacture a fatty acid ester from oil candy according to one Embodiment of this invention, FIG. 1 adds an acid to oil candy, and stirs and mixes And a separation means B for separating a dark oil mainly composed of fatty acids and fats and oils (fats and fats derived mainly from attached oil and fat raw materials) produced by the decomposition reaction from the reaction liquid. And a washing mechanism C for washing the separated dark oil with water, and a reaction mechanism D comprising a tubular reactor and a peripheral device for allowing the dark oil and alcohol to undergo an esterification reaction under conditions where the alcohol is in a supercritical state. FIG.

  Further, FIG. 2 includes distillation of the reaction solution after the esterification reaction is performed in a tubular reactor, and includes a low boiling point component mainly composed of alcohol and water, a fatty acid ester, glycerin, and a high boiling point impurity. Distillation means E for separating high-boiling components, alcohol recovery means F for collecting alcohol by distilling low-boiling components separated by distillation means E, and a small amount of fatty acids contained in the high-boiling components are separated and removed by a neutralization reaction. It is a figure which shows the fatty acid removal means G to do.

  FIG. 3 shows a high-boiling-point impurity removing means H for removing high-boiling-point impurities by distilling the high-boiling components separated by the distillation means E (FIG. 2), and a fatty acid from which the high-boiling-point impurities have been removed by the high-boiling-point impurity removing means. It is a figure which shows the isolation | separation means I which isolate | separates the liquid containing ester and glycerol into fatty acid ester and glycerol.

  As shown in FIG. 1 to FIG. 3, the apparatus for producing a fatty acid ester of the present invention comprises a decomposition reaction means A for causing a decomposition reaction by adding an acid to an oil cake, stirring and mixing, and a reaction solution, Separation means B for separating dark oil mainly composed of fatty acids and fats and oils produced by the decomposition reaction, cleaning means C for washing the separated dark oil with water, and a mixed fluid of dark oil and alcohol, in which the alcohol is in a supercritical state The reaction mechanism part D (FIG. 1) which consists of the tubular reactor 4 and its peripheral equipment which perform an esterification reaction continuously, and after the esterification reaction in the tubular reactor 4 Distilling means E for distilling the reaction liquid into low-boiling components and high-boiling components, alcohol collecting means F for distilling the low-boiling components and recovering alcohol, and a small amount of fatty acid contained in the high-boiling components The high boiling point impurities were separated by the fatty acid removing unit G (FIG. 2) for separating and removing by the reaction, the high boiling point impurity removing unit H for distilling the high boiling point components to remove the high boiling point impurities, and the high boiling point impurity removing unit H. Separation means I (FIG. 3) for separating the fatty acid ester and glycerin in the high-boiling component is provided.

  In this fatty acid ester production apparatus, the decomposition reaction means A is for adding a sulfuric acid to the oil cake, stirring and mixing it, thereby causing the fatty acid soap in the oil cake to undergo a decomposition reaction again to become a fatty acid. It is equipment, so that the reaction to decompose fatty acid soap into fatty acid can be sufficiently performed by adding acid to oil cake until pH is at least 5 and stirring and mixing at 50-120 ° C. It is configured.

Separation means B is a mechanism that separates dark oil mainly composed of fatty acids and fats and oils produced by the decomposition reaction from the reaction liquid after the reaction in the decomposition reaction means. In this embodiment, the decanter type ( (Separation separation type) separation means is used.
The reaction solution after the decomposition reaction is composed of an upper layer composed mainly of free fatty acids and fats and oils, an intermediate layer composed mainly of water-insoluble impurities, and a lower layer aqueous layer. Are separated into three layers.
In this embodiment, a decanter type (stationary separation type) is used as the separation means, but the separation means is not limited to this, and various types such as a centrifugal separation type can be used. It is.
In addition, after the water | moisture content containing a lower layer sulfuric acid, sodium sulfate, etc. is taken out and pH-processed, it is waste-water-treated.
In addition, the middle layer of starch is taken out and discharged as waste.

  Further, the cleaning means C for washing the separated dark oil with water is a mechanism for removing water-soluble impurities contained in the dark oil, so that the dark oil can be separated after contacting the water with water. The specific configuration is not particularly limited, but for example, a centrifugal separation type, a stirring / stationary separation type, or the like can be used. The cleaning means C may be omitted when there are few water-soluble impurities contained in the dark oil.

  The reaction mechanism D (FIG. 1) is preheated in a dark oil preheater 3a that preheats dark oil, an alcohol preheater 3b that preheats alcohol to a temperature below the critical temperature, a dark oil preheater 3a, and an alcohol preheater 3b. Mixing temperature with a mixing mechanism (in this embodiment, an in-line mixer (not shown)) that raises the temperature to a reaction temperature at which the alcohol becomes a supercritical state while mixing the dark oil and alcohol in a liquid phase state A vessel (mixing means) 3c, and a tubular reactor 4 for continuously performing the esterification reaction by passing a mixed fluid of dark oil and alcohol.

  The tubular reactor 4 includes a tubular reactor body 4a in which a pipe having a predetermined length is bent in a folded manner, and a mixed fluid (raw fluid) of dark oil and alcohol in a supercritical region of alcohol. A heater 4b is provided for heating and raising the temperature until a predetermined temperature and pressure are reached, or for maintaining the temperature and pressure. The heater type is not limited to a heating type such as a double-pipe heating type using an heating medium or high-pressure steam or an electric heater type.

  In addition, on the outlet side of the tubular reactor 4, for example, it is possible to provide a heat recovery unit 5 that preheats alcohol and recovers heat by causing heat exchange between the liquid after reaction and alcohol, There are no particular restrictions on the presence or absence of the heat recovery unit 5 and the specific configuration when the heat recovery unit is provided.

  The distillation means E (FIG. 2) for distilling the low boiling point component from the reaction solution after the esterification reaction in the tubular reactor 4 to separate the low boiling point component and the high boiling point component is shown in FIG. A decompression system 11 disposed on the outlet side of the reactor 4, a flash can 13 a that flashes and evaporates a reaction liquid (reacted liquid) exiting the decompression system 11, a buffer tank 12 that receives the decompressed reaction liquid, Evaporation is performed by distilling a low-boiling component mainly composed of alcohol and water from the reaction solution supplied from the buffer tank 12 to separate the low-boiling component from the high-boiling component containing fatty acid ester, glycerin, and high-boiling impurities. Part 13b, high boiling point component tank 14 that receives high boiling point components that have not evaporated in evaporation unit 13b, and alcohol and water vapor evaporated in flash can 13a and evaporation unit 13b. A capacitor 15 to be reduced, and a low-boiling component tank 16 which receives the low-boiling components consisting of alcohol and water condensed in the condenser 15.

  Further, the alcohol recovery means F (FIG. 2) for recovering alcohol by distilling the low boiling point component distills the low boiling point component consisting of alcohol and water supplied from the low boiling point component tank 16 and separates it into alcohol and water. A distillation column 21 and a condenser 22 for condensing alcohol vapor as a fraction are provided.

  Further, the fatty acid removing means G for separating and removing a small amount of fatty acid contained in the high boiling point component by neutralization reaction is used to remove alkali in the line fed from the high boiling point component tank 14 that receives the high boiling point component of the distillation means E. A separator 23 is provided for performing neutralization reaction and separation in a mechanical separator by adding a line. And in this separator 23, the fatty acid soap which is the neutralized impurity is isolate | separated. As this separator 23, it is possible to use a centrifugal separator or various mechanical separators other than the centrifugal separator.

Further, the high boiling point impurity removing means H for distilling the high boiling point components to remove the high boiling point impurities distills the fatty acid ester and glycerin and separates unreacted products and polymerized products (high boiling point impurities) as the residue. A distillation unit 31 composed of a thin film heater and an evaporator, and a condenser 32 for condensing distilled fatty acid ester and glycerin are provided. The distiller 31 is not limited to a thin film heater and an evaporator, and various types can be used.
A trap 35 is disposed in the vacuum line 34 on the downstream side of the capacitor 32.

  Separation means I (FIG. 3) for separating the high-boiling component containing fatty acid ester and glycerin into fatty acid ester and glycerin after removing high-boiling impurities from the high-boiling component is supplied from a capacitor 32 and a trap 35. A separator 36 is provided that separates a liquid containing a fatty acid ester and glycerin into a fatty acid ester and glycerin by a difference in specific gravity using centrifugal force. The separator 36 is not limited to a centrifugal separator, and other types of mechanical separators can be used.

  In this embodiment, a sealed water vacuum pump with a gas ejector is used as the vacuum suction means 37. However, the type of the vacuum suction means 37 is not particularly limited, and other types can be used.

The features of the present invention will be described more specifically with reference to examples of the present invention.
Fatty acid soap, fats and oils obtained by neutralizing and separating free fatty acids with alkalis in the deoxidation step, which is one of the vegetable oil refining steps, using the fatty acid ester production apparatus constructed as described above And the oil cake containing other impurities was processed under the following conditions and procedures to produce fatty acid esters.

[1] Decomposition of oil cake (production of dark oil)
(1) Composition and properties of oil cake Moisture: 30 to 70% by weight
Fatty acid soap and oil: 20-60% by weight
Other impurities (such as gum components): 10 to 50% by weight
(2) Addition of sulfuric acid An oil cake having the above composition is heated to 60 ° C., and concentrated sulfuric acid is added until the pH becomes 3.0 while stirring at low speed.
(3) Reaction temperature The temperature rises to about 80 ° C. due to the heat of reaction caused by the addition of concentrated sulfuric acid.
Then, the decomposition reaction is performed by stirring and mixing at a temperature of about 80 ° C.

By performing the decomposition reaction under the above conditions, it was possible to separate dark oil at a rate of about 40 parts by weight from 100 parts by weight of oil cake.
In this example, the dark oil was dehydrated while being washed with water by a centrifuge.
The composition of the dark oil thus obtained contained fatty acids and fats in the following proportions.
Fatty acid: 60-80% by weight
Fat and oil: 40 to 20% by weight

[2] Production of fatty acid ester from dark oil The fatty oil ester was produced by mixing the dark oil obtained in the above step [1] with alcohol (in this example, methanol) and reacting under the following conditions.
(1) Reaction temperature 300 ° C
(2) Reaction pressure 15-22 MPa
(3) Liquid space velocity: about 0.08 to 0.13 1 / min
(4) Solvent (methanol) addition rate About 0.5 to 1.0 times the weight of dark oil

  Then, methanol and water as a solvent were distilled off from the reaction solution, and fatty acid esters recovered by removing high boiling impurities were analyzed by gas chromatography and gas chromatography / mass spectrometry.

Composition of recovered fatty acid ester (analysis result)
Palmitic acid ester: 6.0%
Oleic acid and stearic acid ester: 44.5%
Linoleic acid ester: 19.3%
Linolenic acid ester: 5.8%
Other fatty acid ester products: 15.2%
Glycerin: 0.8%
Water content: 0.05%
Other: remaining

  As mentioned above, the fatty acid species of the detected fatty acid esters are mainly palmitic acid, oleic acid, linoleic acid, linolenic acid, stearic acid, and some other fatty acid esterified products that cannot identify the fatty acid species It was confirmed that about 90% of the fatty acid esterified product can be finally recovered by performing the distillation operation.

  Moreover, from the above analysis results, it was confirmed that the esterification reaction was sufficiently advanced, and substances other than the fatty acid ester were glycerin, a trace amount of water, and a monoglycerin fatty acid ester.

According to the above embodiment, in the deoxidation step, which is one of the refining steps of fats and oils, the target is obtained from the oil cake containing fatty acid soap, fats and oils, moisture, and other impurities, which are obtained by neutralizing and separating free fatty acids with alkali. It was confirmed that a fatty acid ester having a quality that can be used as a light oil alternative fuel is obtained.
The recovered methanol is also analyzed and confirmed to be of a quality that can be recycled.

  In the above embodiment, methanol is used as the alcohol, but other lower alcohols having 2 to 5 carbon atoms, such as ethanol, propanol, butanol, pentanol, etc., can also be used.

  Moreover, in the said Example, although alcohol (methanol) is preheated, it is also possible to comprise so that the fluid mixture which mixed dark oil and alcohol may be preheated.

  The invention of the present application is not limited to the above-described embodiments and examples in other respects as well, and temperature conditions and pressure conditions such as a tubular reactor, a preheater, and a mixed temperature raising device, and in the tubular reactor. With respect to the liquid space velocity and the like, various applications and modifications can be made within the scope of the invention.

According to the present invention, a fatty acid ester for fuel can be efficiently produced from oil cake.
Therefore, the present invention is an apparatus for treating oil cake containing fatty acid soap, fats and oils, moisture, and other impurities, in which a free fatty acid is neutralized and separated by an alkali in a deoxidation step which is one of the oil purification steps, It can be widely used as a biodiesel production apparatus.

The decomposition reaction means for decomposing oil cake, the separation means for separating dark oil, the washing means for washing the separated dark oil with water, and the dark oil constituting the fatty acid ester production apparatus according to the embodiment of the present invention It is a figure which shows the reaction mechanism part which esterifies and alcohol. The apparatus for producing a fatty acid ester according to an embodiment of the present invention, a distillation means for distilling the reaction liquid to separate the low-boiling component and the high-boiling component, an alcohol collecting means for collecting the alcohol by distilling the low-boiling component, and It is a figure which shows the fatty acid removal means which isolate | separates and removes a small amount of fatty acid contained in the high boiling point component separated by distillation by neutralization reaction. The apparatus for producing a fatty acid ester according to an embodiment of the present invention includes a high-boiling-point impurity removing unit that distills a high-boiling component and removes a high-boiling impurity, and a fatty acid ester from which the high-boiling impurity is removed and glycerin. It is a figure which shows the isolation | separation means which isolate | separates a liquid into fatty acid ester and glycerol.

Explanation of symbols

A Decomposition reaction means B Separation means C Washing means D Reaction mechanism E Distillation means F Alcohol recovery means G Fatty acid removal means H High boiling point impurity removal means I Separation means 3a Dark oil preheater 3b Alcohol preheater 3c Mixing heating device (mixing) means)
4 Tubular reactor 4a Reactor body 4b Heater 5 Heat recovery unit 11 Depressurization system 12 Buffer tank 13a Flash can 13b Evaporation unit 14 High boiling point component tank 15 Capacitor 16 Low boiling point component tank 21 Distillation tower 22 Capacitor 23 Separator 31 Distiller 32 Capacitor 34 Vacuum line 35 Trap 36 Separator 37 Vacuum suction means (sealed water vacuum pump with gas ejector)

Claims (3)

In order to produce a fatty acid ester for fuel from an oil cake containing fatty acid soap, fats and oils, water, and other impurities, in which a free fatty acid is neutralized and separated by an alkali in a deoxidation step, which is one of the oil refining steps An apparatus for producing a fatty acid ester for fuel,
(a) Heating the oil cake to 50 to 120 ° C. so that sulfuric acid can be added to the oil cake until the pH is at least 5 and to which the sulfuric acid has been added until the pH is 5 or less. A decomposition reaction means for decomposing the oil cake, which is configured to be stirred and mixed;
(b) separation means for separating dark oil mainly composed of fatty acids and fats and oils produced by the decomposition reaction from the reaction liquid subjected to the decomposition reaction in the decomposition reaction means;
(c) washing means for washing the dark oil separated by the separation means with water;
(d) a mixing means for mixing the dark oil washed by the washing means with about 0.5 to 1.0 times the weight of the dark oil and a lower alcohol having 1 to 5 carbon atoms; and the mixing means A mixed liquid mixed with a lower alcohol is supplied at a liquid space velocity of about 0.08 to 0.13 1 / min, and the lower alcohol is supercritical within a temperature range of 200 to 350 ° C. and a pressure of 15 to 25 MPa. And a reaction mechanism unit including a tubular reactor that performs an esterification reaction under conditions to be in a state. further,
(e) Distilling the reaction liquid in which the esterification reaction has been performed in the reaction mechanism unit, a low boiling point component containing alcohol and water as main components, and a high boiling point containing fatty acid, fatty acid ester, and high boiling point impurities as main components Distillation means to separate the components;
(f) an alcohol recovery means for recovering alcohol by distilling the low boiling point component;
(g) fatty acid removing means for separating and removing fatty acids contained in the high boiling point component by a neutralization reaction;
(h) a high boiling point impurity removing unit that distills a high boiling point component separated and removed by the fatty acid removing unit to remove a high boiling point impurity as a residue of the kettle;
(i) separating means for separating the fatty acid ester and glycerin in the high-boiling component from which the high-boiling-point impurities have been separated by distillation in the high-boiling-point impurity removing means, into a fatty acid ester and glycerin due to a difference in specific gravity. The apparatus for producing a fatty acid ester for fuel according to claim 1.   The mixing means constituting the reaction mechanism unit is configured to increase the temperature to a reaction temperature at which the lower alcohol becomes a supercritical state while mixing the dark oil and the lower alcohol in a liquid phase state. The apparatus for producing a fatty acid ester for fuel according to claim 1 or 2, wherein the fuel fatty acid ester is produced.

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