JP3869385B2 - Method for producing fuel fatty acid ester from oil cake - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to the production how the fatty acid ester, particularly, in the deoxidation step which is one of the fat purification step, the free fatty acids were separated and neutralized with an alkali, fatty acid soaps, oils, moisture, and It relates to the production how the fuel fatty acid esters from oil dregs contain other impurities.
[0002]
[Prior art and problems to be solved by the invention]
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.
[0003]
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.
[0004]
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 fuel and crude fatty acid, and in recent years, it has been sought for applications with higher added value.
[0005]
The present invention has been made in view of such circumstances, and a fatty acid for fuel capable of producing a fatty acid ester having a high added value from an oil cake generated in a deoxidation process which is one of the oil refining processes. and to provide a manufacturing how ester.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the method for producing a fatty acid ester for fuel according to the present invention (Claim 1) comprises:
A method for producing a fatty acid ester from an 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 purification steps of fats and oils. ,
(a) adding sulfuric acid to the oil cake until at least pH is 5 or less, stirring and mixing at 50 to 120 ° C. to cause a decomposition reaction;
(b) separating a dark oil mainly comprising fatty acids and fats produced by the decomposition reaction from the reaction solution;
(c) After the separated dark oil is washed with water, the dark oil and about 0.5 to 1.0 times the weight of the dark oil are mixed with a lower alcohol having 1 to 5 carbon atoms, and the mixture is mixed. The alcohol is in a supercritical state while being supplied to the tubular 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 And a step of producing a fatty acid ester used as a fuel by performing an esterification reaction under the conditions of ° C and pressure: 15 to 25 MPa.
[0007]
After adding the acid to the oil cake, stirring and mixing to cause the decomposition reaction, the main components are fatty acids and fats and oils (fats and fats derived mainly from the attached raw material fats and oils) generated by the decomposition reaction from the reaction liquid. It is possible to efficiently produce fatty acid esters from oil cake by separating the dark oil to be mixed, mixing the dark oil and alcohol, and allowing the alcohol to undergo an esterification reaction under conditions that make it supercritical. Become.
[0008]
In addition, acid is added to the oil cake until at least the pH is 5 or less, and the mixture is stirred and mixed at 50 to 120 ° C. to cause the decomposition reaction, so that the oil cake can be efficiently decomposed. The resulting dark oil is mixed with alcohol to allow the esterification reaction to be carried out under conditions where the alcohol is in a supercritical state. Become.
[0009]
Further, since sulfuric acid is used as the acid added to the oil cake, the oil cake can be reliably decomposed without increasing the cost, and the present invention can be more effectively presented.
[0010]
Moreover, after separating the dark oil produced | generated by decomposition | disassembly reaction, it wash | cleans with water, the dark oil washed with water, about 0.5-1.0 weight times of this dark oil, and C1-C5 lower alcohol, The mixture is supplied to a tubular reactor, and the alcohol is in a supercritical state while passing through the tubular reactor at a liquid space velocity of about 0.08 to 0.13 1 / min. Since the esterification reaction is performed under the conditions of temperature: 200 to 350 ° C. and pressure: 15 to 25 MPa, it becomes possible to efficiently react the alcohol in the critical state with the dark oil. Can be effective.
That is, in the present invention, the temperature and pressure conditions for carrying out the esterification reaction are in the range of temperature: 200 to 350 ° C. and pressure: 15 to 25 MPa, so that the alcohol is surely brought into a supercritical state. Can do.
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 if the reaction pressure is less than 15 MPa, the esterification reaction in the next step becomes insufficient, and if it exceeds 25 MPa, the equipment cost is significantly increased.
[0011]
Further, since the lower alcohol having 1 to 5 carbon atoms is used as the alcohol, it becomes possible to make the alcohol into a supercritical state under a practical temperature condition and pressure condition, and the present invention is effectively realized. be able to. Examples of the lower alcohol having 1 to 5 carbon atoms include methanol, ethanol, propanol, butanol, pentanol and the like.
[0012]
Further, since the separated dark oil is washed with water and then subjected to the esterification reaction step, water-soluble impurities in the dark oil can be removed to produce a high-purity fatty acid ester.
[0013]
Moreover, according to this invention, it becomes possible to manufacture a highly purified fatty acid ester, and the fatty acid ester which can be efficiently used as a fuel (light oil alternative fuel) can be manufactured from an oil tank.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the features of the present invention will be described in more detail with reference to embodiments of the present invention.
[0015]
1-3 is a figure which shows the manufacturing apparatus used in order to implement the manufacturing method of the fatty acid ester from the oil candy concerning one Embodiment of this invention, FIG. 1 adds an acid to oil candy. , A decomposition reaction means A for performing a decomposition reaction by stirring and mixing, and a dark oil mainly composed of fatty acids and fats and oils (fats and fats derived mainly from attached oil and fat raw materials) generated by the decomposition reaction from the reaction solution Separating means B for washing, washing means C for washing the separated dark oil, and a tubular reactor and its peripheral equipment for allowing the dark oil and alcohol to undergo an esterification reaction under the condition that the alcohol is in a supercritical state. It is a figure which shows the reaction mechanism part D. FIG.
[0016]
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.
[0017]
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.
[0018]
As shown in FIG. 1 to FIG. 3, the production apparatus used for carrying out the method for producing a fatty acid ester of the present invention is a decomposition in which a decomposition reaction is performed by adding an acid to oil cake, stirring and mixing. Reaction means A, separation means B for separating dark oil mainly composed of fatty acids and fats and oils produced by decomposition reaction from the reaction solution, cleaning means C for washing the separated dark oil with water, and dark oil and alcohol A reaction mechanism D (FIG. 1) composed of a tubular reactor 4 and its peripheral devices for continuously performing an esterification reaction by allowing the mixed fluid to pass under a condition where the alcohol is in a supercritical state; A distillation means E for distilling the reaction liquid after the esterification reaction in the reactor 4 into a low boiling point component and a high boiling point component, an alcohol recovery means F for distilling the low boiling point component and recovering alcohol, and a high boiling point component. Fatty acid removing means G (FIG. 2) for separating and removing a small amount of fatty acid contained therein by neutralization reaction, high boiling point impurity removing means H for distilling high boiling point components to remove high boiling point impurities, and high boiling point impurity removal Separation means I (FIG. 3) for separating fatty acid ester and glycerin in the high-boiling component from which high-boiling impurities have been separated by means H is provided.
[0019]
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.
[0020]
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.
[0021]
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.
[0022]
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 stirring mechanism (in this embodiment , an in-line mixer (not shown)) that raises the temperature to a reaction temperature at which the alcohol becomes supercritical while mixing the dark oil and alcohol in a liquid phase state A vessel 3c, and a tubular reactor 4 for continuously performing an esterification reaction by passing a mixed fluid of dark oil and alcohol.
[0023]
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.
[0024]
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.
[0025]
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.
[0026]
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.
[0027]
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.
[0028]
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.
[0029]
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 for separating a liquid containing a fatty acid ester and glycerin into a fatty acid ester and glycerin by centrifugal force. The separator 36 is not limited to a centrifugal separator, and other types of mechanical separators can be used.
[0030]
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.
[0031]
【Example】
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.
[0032]
[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.
[0033]
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
[0034]
[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.
[0036]
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 [0037]
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.
[0038]
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.
[0039]
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.
[0040]
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.
[0041]
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.
[0042]
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.
[0043]
【The invention's effect】
As described above, in the method for producing a fatty acid ester for fuel according to the present invention (Claim 1), an acid is added to the oil cake, and after stirring and mixing, the decomposition reaction is performed, Since the dark oil mainly composed of fatty acids and fats and oils generated by the decomposition reaction is separated, this dark oil and alcohol are mixed, and the esterification reaction is performed under the condition that the alcohol is in a supercritical state. Thus, it becomes possible to efficiently produce fatty acid esters from oil cake.
[0044]
In addition, an acid is added to the oil cake until at least the pH is 5 or less, and the mixture is stirred and mixed at 50 to 120 ° C. to cause the decomposition reaction, so that the oil cake can be efficiently decomposed. Thus, the fatty acid ester can be produced from the oil cake in a high yield by mixing the obtained dark oil with the alcohol and allowing the esterification reaction to be performed under the condition that the alcohol is in a supercritical state.
[0045]
In addition, since sulfuric acid is used as the acid added to the oil cake, it becomes possible to reliably decompose the oil cake without incurring an increase in cost, and to make the present invention more effective. Become.
[0046]
Moreover, after separating the dark oil produced | generated by decomposition | disassembly reaction, it wash | cleans with water, the dark oil washed with water, about 0.5-1.0 weight times of this dark oil, and C1-C5 lower alcohol, The mixture is supplied to a tubular reactor, and the alcohol is in a supercritical state while passing through the tubular reactor at a liquid space velocity of about 0.08 to 0.13 1 / min. Since the esterification reaction is performed under the conditions of temperature: 200 to 350 ° C. and pressure: 15 to 25 MPa, it becomes possible to efficiently react the alcohol in the critical state with the dark oil. Can be effective.
That is, in the present invention, by setting the temperature condition and the pressure condition when performing the esterification reaction to the temperature: 200 to 350 ° C. and the pressure: 15 to 25 MPa, the alcohol is surely brought into a supercritical state. And the present invention can be effectively realized.
[0047]
Further, since the lower alcohol having 1 to 5 carbon atoms is used as the alcohol, it becomes possible to make the alcohol into a supercritical state under a practical temperature condition and pressure condition, and the present invention is effectively realized. be able to.
[0048]
Further, since the separated dark oil is washed with water and then subjected to an esterification reaction step, it becomes possible to produce a high purity fatty acid ester by removing water-soluble impurities in the dark oil.
[0049]
Moreover, according to this invention, it becomes possible to manufacture a highly purified fatty acid ester, and it becomes possible to manufacture the fatty acid ester which can be efficiently used as a fuel (light oil alternative fuel) from an oil tank. .
[Brief description of the drawings]
FIG. 1 shows a production apparatus used for carrying out a method for producing a fatty acid ester according to an embodiment of the present invention, a decomposition reaction means for decomposing oil cake, a separation means for separating dark oil, It is a figure which shows the reaction mechanism part which esterifies the washing | cleaning means which wash | cleans the isolate | separated dark oil, and dark oil and alcohol.
FIG. 2 is a distillation means for separating a low boiling point component and a high boiling point component by distilling a reaction liquid in a production apparatus used for carrying out the method for producing a fatty acid ester according to an embodiment of the present invention; It is a figure which shows the alcohol collection | recovery means to collect | recover alcohol by distilling, and 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.
FIG. 3 is a high-boiling-point impurity removing means for removing a high-boiling-point impurity by distilling a high-boiling-point component, which constitutes a production apparatus used for carrying out the method for producing a fatty acid ester according to an embodiment of the present invention; It is a figure which shows the isolation | separation means which isolate | separates the liquid containing fatty acid ester and glycerol from which the high boiling point impurity was removed into fatty acid ester and glycerol.
[Explanation of symbols]
A decomposition reaction means B separation means C washing means D reaction mechanism part 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 temperature riser 4 pipe Type 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 (1)

A method for producing a fatty acid ester from an 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 that is one of the steps of oil purification. ,
(a) adding sulfuric acid to the oil cake until at least pH is 5 or less, stirring and mixing at 50 to 120 ° C. to cause a decomposition reaction;
(b) separating a dark oil mainly comprising fatty acids and fats produced by the decomposition reaction from the reaction solution;
(c) After the separated dark oil is washed with water, the dark oil is mixed with a lower alcohol having 1 to 5 carbon atoms that is about 0.5 to 1.0 times the weight of the dark oil, and the mixture is The alcohol is in a supercritical state while being supplied to the tubular 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 And a step of producing a fatty acid ester used as a fuel by performing an esterification reaction under the conditions of ° C. and pressure: 15 to 25 MPa.

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