JP2008231345A - Method for producing biodiesel fuel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a biodiesel fuel which enables the use of, as a raw material, the whole oils and fats with an acid value of 20 or less, is friendly to the environmental, does not need waste water treatment, and also is adapted to the quality specification. <P>SOLUTION: The method for manufacturing a biodesel fuel uses, as a raw material, oils and fats having an acid value of 20 or less, and comprises a step of heating the raw material oils under reduced pressure to thereby distill off water, odor substances and free fatty acids, a step of bringing the raw material oils into contact with a hydrophilic adsorbent, to thereby adsorb and then remove the remaining free fatty acids and acidic substances, a step of transesterifying it in the presence of a potassium-based alkali catalyst and a step of purifying by a nonaqueous method a light liquid component in the reaction product by the transesterification. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a high-quality fatty acid biodiesel fuel oil with a high conversion rate from deteriorated fats and oils such as waste cooking oil.

  The biodiesel fuel is generally a fuel for diesel engines by subjecting a vegetable oil and alcohol to a transesterification reaction to obtain a fatty acid alkyl ester. It is an oxygen-containing fuel that contains oxygen in its chemical structure, and since it contains almost no sulfur, it emits less harmful exhaust gases such as black smoke. In addition, because it is derived from plants, carbon dioxide emissions are set to zero in accordance with the provisions set forth in the Kyoto Protocol. For this reason, it is attracting attention as an alternative to light oil with a low environmental impact. In Europe and the United States, standards and legal systems have already been established, and in fiscal 2005, more than 5 million tons are produced and used annually from soybeans and rapeseed oil. . On the other hand, in Japan, about 10,000 tons / year is produced from waste cooking oil and is used only in local governments. In January 2007, a quality standard was established for biodiesel fuel on the premise of 5% blending with diesel oil (B5).

  It has long been known that fatty acid alkyl esters can be obtained by transesterifying monoglycerides, diglycerides and triglycerides, which are the main components of fats and oils, with alkyl alcohols. On the other hand, it is known that a fatty acid alkyl ester can also be obtained by an esterification reaction between a free fatty acid and an alkyl alcohol (see, for example, Non-Patent Document 1). In addition, various techniques have been studied so far for producing biodiesel fuel oil from fats and oils using this reaction. In particular, in recent years, a number of related patents have been filed under an economic background such as a rise in oil prices (see, for example, Patent Documents 1 to 11). In these documents, attempts have been made to improve the efficiency of esterification from various feedstocks and to keep impurities as little as possible.

  By the way, generally, the manufacturing method of a fatty-acid alkylester type | mold biodiesel fuel oil is divided roughly into the following three types.

(1) Homogeneous, heterogeneous acid, alkali catalysis (2) High-temperature, high-pressure non-catalytic reaction (3) Enzymatic reaction Among these, the most widely used reaction system is the catalytic method (1) It is. (2) and (3) are superior in that no catalyst residue is produced and the esterification reaction proceeds simultaneously with the transesterification reaction, but still in various aspects such as reaction conversion rate, initial cost and running cost. At present, it has not been put into practical use.

  Various methods for the catalytic method (1) have been reported, and are classified as follows.

[1] Acid catalyst (uniform)
[2] Acid catalyst (non-uniform)
[3] Alkaline catalyst (uniform)
[4] Alkaline catalyst (non-uniform)
[5] Acid catalyst (homogeneous)-alkali catalyst (homogeneous) {two-stage method}
[6] Acid catalyst (heterogeneous)-alkali catalyst (homogeneous) {two-stage method}
[7] Acid catalyst (heterogeneous)-alkali catalyst (heterogeneous) {two-stage method}
[8] Acid catalyst (homogeneous)-alkali catalyst (heterogeneous) {two-stage method}
The acid catalyst is both homogeneous and heterogeneous, but in the alkaline catalyst, only a homogeneous system has been put into practical use. This is because the conversion rate is not sufficient in other methods.

  As mentioned above, fatty acid alkyl ester biodiesel fuel oil has already been severely standardized in Europe and the US based on standards such as EN14214 and ASTM D6751, but it will be even more rigorous by incorporating opinions from the automobile industry in the future. A standard is scheduled to be enacted. These movements are inevitable, and the biodiesel fuel has been placed at the center of alternative fuels, taking off from the preferential era of environmental fuels.

  Here, it is necessary to provide a refining process in order to produce fuel oil that conforms to the above standards. In the case of the alkali catalyst method, which is a general method for producing biodiesel fuel oil, there are two methods, a water washing method and an adsorption method.

  When the conversion rate of the transesterification reaction of the raw material oil is about 98%, it is necessary to remove the soap, alcohol, glycerin, salt or glyceride derivative remaining in the order of several thousand ppm by washing with water (Patent Document 12 and the like). reference). Thereafter, moisture is removed by heating. Due to the effect of washing with water, there is a high possibility that glycerin, alcohol and metals (K, Na, etc.) in the product will be within the limits of the regulation values. However, with regard to moisture, even if thorough removal is performed including heating and distillation, the limit is about 500 ppm. If further heating is performed in order to lower the moisture level beyond this, biodiesel itself may be decomposed during these purification processes. In addition, a serious problem in the water washing method is waste water. About 1 to 3 tons of wastewater is produced to produce 1 ton of biodiesel fuel oil. According to the Act on Prevention of Marine Pollution in 2007, these wastewaters can be disposed of only after they are completely treated. The cost increase due to this will be enormous.

  On the other hand, the adsorbent method has a precondition that it can be used when the conversion rate is 99% or more using raw oils with free fatty acids of 3000ppm or less, salts 5000ppm or less, and moisture 1000ppm or less. Biodiesel fuel oil can be refined and manufactured with a quality equivalent to or higher than that of the water washing method with respect to impurities other than moisture (see Patent Documents 13 to 15). The advantages that are greatly different from the water washing method are that the amount of water in the biodiesel fuel oil is extremely small and that no waste water is produced.

  However, when producing according to the production method described in the above patent document, depending on the situation of the raw material oil before the reaction and the situation of the fatty acid alkyl ester after the reaction, a moisture value of 200 ppm, which is a standard value for biodiesel fuel set after 2007 Hereinafter, it is difficult to achieve an alcohol value of 1000 ppm or less and an acid value of 0.3 or less.

  In addition, when considering future biodiesel fuel standards and environmental load problems, purification by a non-aqueous method that does not produce wastewater is a suitable method, but using this non-aqueous method, the moisture value is 200 ppm or less and the alcohol value is 1000 ppm or less. There is no method for producing biodiesel fuel that always achieves an acid value of 0.3 or less.

  By the way, most of the raw materials for producing fatty acid alkyl ester type biodiesel fuel oil are fatty acid glycerol esters, and the production method from these is mainly transesterification by alcoholysis. Therefore, the most mainstream reaction is a transesterification reaction using sodium hydroxide or potassium hydroxide catalyst in alcohol corresponding to the above [3] alkali catalyst (uniform) (see, for example, Patent Document 16).

  However, fresh vegetable oils and animal oils with glycerol esters refined to 100% are difficult to obtain, and as the demand for biodiesel fuel oil increases, degraded oils such as bad oils and waste cooking oils are also used as raw oils. There is a movement to use as. These main impurities are free fatty acids.

  If a large amount of free fatty acids are contained in the transesterification reaction, they first react with the alkali metal as a catalyst to produce an alkali soap, which not only lowers the reaction yield but also causes an emulsion, making purification difficult. become. Therefore, in the production of a fatty acid alkyl ester fuel by transesterification under an alkali catalyst, it is necessary to control the amount of free fatty acid in the feedstock.

  If the free fatty acid in the raw material oil is to be converted into a fatty acid alkyl ester, it is necessary to carry out an esterification reaction between the free fatty acid and an alcohol. Since the esterification reaction is an equilibrium reaction, the excess is used as one of the raw materials, or the water generated as a side reaction product is removed to shift the equilibrium to the production system and increase the yield. .

  In order to further increase the reaction rate, a catalyst is generally used. Generally, an acidic catalyst is often used in an industrialization process in an esterification reaction of a fatty acid. For example, inorganic acids such as sulfuric acid and phosphoric acid, and organic acids such as p-toluenesulfonic acid are esterification catalysts. However, since these reactions are basically a homogeneous reaction system in which the catalyst is dissolved in the reaction solution, there is a problem that it is difficult to separate and recover the catalyst from the product solution. Further, as a method for solving such a problem, an immobilized or solid acid catalyst is often used, and a sulfonic acid ion exchange resin or a solid acid catalyst in which a heteropoly acid is supported on silica gel or activated carbon is known. However, when these immobilization or solid acid catalysts are used, the esterification reaction proceeds sufficiently, but by itself, the conversion rate is low for the transesterification reaction.

  As the esterification method of fats and oils containing free fatty acids, [5] acid catalyst (homogeneous) -alkali catalyst (homogeneous) {two-stage method} or [6] acid catalyst (heterogeneous) -alkali catalyst (homogeneous) { There is a report on a method of first esterifying with an acid catalyst including a solid acid catalyst and then performing an ester exchange reaction with an alkali catalyst (see Patent Documents 17 to 19). However, the reaction is complicated by a two-catalyst system with completely different properties, and the first reaction needs to be constantly controlled by the amount of fatty acid. Further, if the amount of free fatty acid is 20% or more, profitability with investment in a complicated process plant can be achieved, but if it is 20% or less, for example, it becomes excessive investment.

  In order to solve these problems, high-temperature and high-pressure methods and enzyme methods have been reported. In the high-temperature and high-pressure method, esterification and transesterification can be simultaneously performed in a supercritical state of alcohol (see Patent Documents 20 to 25, etc.).

  However, as far as the inventors have scrutinized, in the esterification reaction of free fatty acid, since the conversion rate is about 98%, final purification is required, and further oxidation of the fatty acid site or double bond at high temperature is required. There is a tendency for complex reactions such as isomerization to occur. In addition, since the cost of the apparatus is high and the operation is difficult, there is a part that is difficult to put into practical use in terms of economy.

  In contrast, esterification reactions using enzymes have also been reported. In the reaction with lipase, esterification and transesterification proceed simultaneously. Furthermore, by immobilizing lipase on a carrier, the number of cycles can be increased and the production of waste can be suppressed (see Patent Document 26 or 27). However, because it is a biological response, just because the reaction conditions are mild, problems remain in reaction rate and conversion.

  Based on the above, in the case of fats and oils whose amount of free fatty acids that can be widely used as fats and oils as raw materials for biodiesel fuel oil production is 10% or less (acid value <20), It is considered suitable to carry out the transesterification by the alkali catalyst method after removing as impurities and making the raw material oil only fatty acid glyceride derivative. However, it is difficult to realize such a method for the following reason.

  First, there is a method for removing free fatty acids from raw material fats, that is, a deoxidation method, which has been established as a purification method in fats and oils chemistry. By this treatment, the content of free fatty acids in fats and oils is 0.01-0.03%. (See, for example, Non-Patent Document 2). In this method, a cleaning method using a weak alkaline aqueous solution is generally used. However, in this method, alkaline waste liquid is generated, and this processing is costly. Further, after washing, a process for removing water in the fats and oils prior to the transesterification reaction is required, which complicates the process.

  On the other hand, as a deoxidation method for fats and oils having a low content of unsaturated fatty acids such as palm oil, that is, a low iodine value, there is a physical purification method, that is, a vacuum steam distillation method. In this method, treatment is performed at 200 to 250 ° C. under reduced pressure for 1 to 2 hours. Although this method has high removal efficiency, fats and oils containing a large amount of unsaturated fatty acids, that is, fats and oils with a high iodine value (over 80), dimer formation and fatty acid structure changes occur under the above processing conditions. Oil is limited and not suitable for oxidatively degraded oil.

  Therefore, the deoxidation method in general fat and oil chemistry cannot be used as it is as a free fatty acid removal method which is a pretreatment of biodiesel fuel production using various fats and oils and their oxidatively deteriorated oils as raw oils.

Furthermore, for the purpose of removing moisture and odorous substances in the waste cooking oil, there is a method in which the waste cooking oil is heated under reduced pressure before reacting with alcohol (see Patent Documents 28 to 30), but free fatty acids are mentioned. Absent. In fact, when oxidized and degraded oils (general waste cooking oil) with an acid value of 5 were treated under the treatment conditions (60 mmHg, 84 ° C) made in the examples in the patent, the amount of free fatty acids after treatment was 1.5% or more (acid (Value 3 or more) remained, and the reaction conversion rate thereafter was as low as 97.5%. When the conditions were further tightened (10 mmHg, 180 ° C) to reduce the amount of free fatty acids, the ratio of fatty acid components oleic acid, linoleic acid and linolenic acid alkyl ester components in the biodiesel product was In addition, the reaction conversion rate was 97.5%. When the conditions were further tightened and the treatment was performed at 5 mmHg and 200 ° C., an increase in the pour point considered to be due to isomerization of the fatty acid moiety from cis to trans was also observed.
JP 2002-167356 A JP 2002-294277 A JP 2000-44984 A JP 2000-109883 A European Patent Application No. 1644470 European Patent Application No. 1616853 European Patent Application No. 1542960 US Patent Application Publication No. 2006/111579 US Patent Application Publication No. 2006/094890 US Patent Application Publication No. 2006/080891 US Patent Application Publication No. 2006/074256 European Patent Application Publication No. 0249463 Japanese Patent Laid-Open No. 10-245586 Japanese Patent Laid-Open No. 10-231497 US Pat. No. 5,972,057 JP-A-7-197047 US Pat. No. 6,642,399 US Pat. No. 6,965,044 US Patent Application Publication No. 2004/102640 JP 2000-109883 A JP 2000-143586 A European Patent Application No. 1506996 US Pat. No. 6,187,939 US6818026 US Pat. No. 6,288,251 International Publication No. 01/038553 JP 2002-233393 A Japanese Patent Laid-Open No. 10-245586 Japanese Patent Laid-Open No. 10-231497 US Pat. No. 5,972,057 "Organic Chemistry Handbook", Gihodo Publishing, 1988, p1407-p1409 Industrial book publishing / Introduction to fats and oils chemistry

  Therefore, the present invention can use as a raw material all fats and oils having an acid value of 20 or less, which can be raw oils and fats of biodiesel fuel oil, from the viewpoint of economy, compatibility with foods and quantitative aspects. It is an object of the present invention to provide a method for producing biodiesel fuel that has a low environmental impact and does not need to be applied, and that can be adapted to the standard values of impurities produced in the quality standards after 2007.

  As a result of intensive studies in view of the above problems, the present inventor, in a biodiesel fuel production method including a step of transesterification of raw oil and alcohol in the presence of an alkali catalyst, water content prior to the transesterification reaction. , Removal of odorous substances and free fatty acids with a hydrophilic adsorbent, use of a catalyst containing potassium as an alkali catalyst, purification of a reaction product of a transesterification reaction with a basic substance adsorbing solid adsorbent, etc. Thus, it has been found that high-quality biodiesel fuel can be produced by using a method with less environmental load using oils and fats having an acid value of 20 or less such as waste cooking oil as a raw material, and the present invention has been completed.

  That is, the present invention is a method for producing biodiesel fuel from a raw material oil having an acid value of 20 or less, the raw oil being heated under reduced pressure to distill off moisture, odorous substances and free fatty acids, Contacting the raw material oil with a hydrophilic adsorbent to adsorb and remove the remaining free fatty acids and acidic substances; and the raw material oil and the alcohol at least selected from the group consisting of potassium hydroxide, potassium carbonate, and potassium alcoholate A step of transesterification in the presence of a kind of alkali catalyst, a step of separating a light liquid component from a reaction product by the transesterification reaction, and contacting the light liquid component with a basic substance-adsorbing solid adsorbent Treatment, removal of solid impurities by centrifugation, treatment to remove low-boiling substances by heating under reduced pressure, solid impurities, etc. through a filter And performing a process, of removing, providing a method of producing a biodiesel fuel containing.

  According to such a method, before the raw fats and oils are reacted with alcohol, acidic substances such as moisture, odorous substances and free fatty acids are removed, so that the activity of the alkali catalyst in the transesterification reaction does not decrease. . In addition, since it is possible to prevent a large amount of water, fatty acid alkali soap, odorous substances and the like from remaining in the fatty acid alkyl ester after the reaction is completed, the subsequent purification process is also low energy, low cost and has a low environmental impact. It is possible to obtain a biodiesel fuel in which the amount of impurities such as moisture, alkali metal, free fatty acid and the like meets the fuel standard value. Furthermore, by removing free fatty acids and water before the reaction, side reactions and the formation of fatty acid soap due to the direct reaction of free fatty acids are suppressed. As a result, emulsions are less likely to occur. The specific gravity separation step and the like are also facilitated.

  In addition, since the removal of free fatty acids and moisture is performed in two stages, heating under reduced pressure and adsorption with a hydrophilic adsorbent, there are problems associated with the above-described washing method using an alkaline aqueous solution, reduced-pressure steam distillation method, and reduced-pressure heat treatment method. Does not occur.

  Furthermore, since the light liquid component is purified by a non-aqueous method, the saponification reaction does not proceed by contact with water, and the problem of wastewater treatment does not occur. Moreover, according to the solid adsorbent column, impurities such as residual catalyst can be easily removed and the process can be continued, so that workability is improved; specific gravity separation is forcibly performed by centrifugation. It is possible to remove traces of high-specific gravity substances such as glycerol, glycerin derivatives, fine adsorbents, etc. with high accuracy; by heating and decompression treatment, low-boiling substances such as alcohol and water in light liquids can be removed. It is possible to remove thoroughly; there is also an effect that solid impurities such as aggregated substances can be removed by passing through a filter. Through these processes, it is possible to adapt to the fuel standard value regardless of manufacturing process variations, and it is also possible to deal with precision diesel engines using the common rail system for values not specified by the fuel standard value. Biodiesel fuel can be produced.

  In the method for producing biodiesel fuel according to the present invention, the hydrophilic adsorbent is preferably at least one selected from the group consisting of activated alumina, basic treated activated carbon, and silica gel.

  According to these hydrophilic adsorbents, remaining acidic impurities such as free fatty acids can be efficiently removed with a small amount of adsorbent from the raw material oil after the heat and pressure reduction treatment.

  In addition, the transesterification reaction step of the method for producing biodiesel fuel according to the present invention is performed at 1.05 to 1.25 molar equivalent of alcohol with respect to the fatty acid portion of the feedstock, and 0.5% by weight with respect to the feedstock. It is preferable to include a step of dissolving a 2.0 wt% alkali catalyst to prepare a catalyst-containing alcohol solution, and a step of mixing and stirring the raw material oil and the catalyst-containing alcohol solution.

  Thus, by using said concentration as an alkali catalyst, the catalyst activity with respect to transesterification is fully acquired, and the conversion rate can be 98% or more by a short time reaction.

  The step of separating the light liquid component is preferably performed by centrifuging the reaction product. Centrifugation enables high-efficiency separation in a short time compared to the case of stationary separation using a specific gravity difference, and can be used for continuous operations with other processes. .

  The basic substance-adsorbing solid adsorbent is preferably at least one selected from the group consisting of activated clay, acidic clay, activated carbon, bentonite, silica gel, activated alumina, and molecular sieves. According to these solid adsorbents, impurities contained in the light liquid can be adsorbed and removed with high efficiency. In particular, activated clay and activated carbon have excellent dealkalizing effect, decoloring effect, and deodorizing effect, and have a certain fastness, and therefore can be suitably used as a column filler.

  Moreover, before performing the process which heats a light liquid component under reduced pressure, it is preferable to add a pour point depressant and an oxidation stabilizer to the light liquid. According to such a method, additives such as a pour point depressant and an acid value stabilizer can be uniformly dissolved without condensing in the biodiesel product.

  Further, in the method for producing biodiesel fuel according to the present invention, prior to the step of distilling off the odorous substances and free fatty acids described above, the step of separating water or an aqueous solution from the feedstock by specific gravity, and the feedstock after the specific gravity separation. It is also preferable to perform the step of removing the solid substance with a filter. By such pretreatment, water and aqueous solution in the raw material oil can be further removed, and heating under reduced pressure and removal of moisture and the like by the hydrophilic adsorbent can be performed more efficiently.

  The alcohol used in the transesterification reaction is preferably at least one selected from the group consisting of methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, and t-butyl alcohol. According to these alcohols, the glycerides in the raw oil and fat are converted into fatty acid alkyl esters with a high conversion rate by transesterification.

  In the method for producing biodiesel fuel according to the present invention, it is preferable that all the steps described above are performed continuously. According to the continuous operation, it is possible to operate as a mass production plant even when the site and space are limited. In order to perform all the processes in a continuous manner, for example, a plurality of tanks used for time-consuming processes are prepared and connected in parallel with the tanks for performing the previous and subsequent processes, and the centrifugal separation method is used for various separation processes. Thus, a method of shortening the time can be used as appropriate.

  Furthermore, the method for producing biodiesel fuel according to the present invention preferably includes a step of obtaining glycerin as a by-product. Specifically, the step includes the step of neutralizing the heavy liquid component after separating the light liquid component from the reaction product by adding sulfuric acid or phosphoric acid, and the resulting inclusion hydrate or water. And a step of distilling the filtrate after separating the hydrated potassium sulfate crystals or the hydrated potassium phosphate crystals under reduced pressure to obtain glycerin as a by-product.

  Since the heavy liquid contains most of the catalyst used in the reaction in addition to glycerin, which is the main component, in order to use it as a fuel, a special boiler is generally required for alkaline corrosion, and the pressure is reduced. When distillation is performed, polyglycerol is produced and the distillation yield is 50% or less. Furthermore, when neutralization with an acid that is generally performed is performed, a highly viscous slurry or semi-solid is obtained, and salt filtration and distillation are extremely difficult. However, according to the method according to the present invention, the salt after neutralization has a large crystal structure as a water-containing crystal of an acid potassium salt, so that the acid potassium salt can be separated quickly and the system does not become highly viscous. Easy to filter. Furthermore, subsequent distillation can be performed very easily, and high-purity glycerin can be obtained in a high yield.

  The method for producing biodiesel fuel according to the present invention includes removing water, odorous substances and free fatty acids from raw material oil as much as possible, then performing a transesterification reaction in the presence of an alkali catalyst, and converting the product after the reaction into a non-aqueous system. As a result, it is possible to use degraded fats and oils with an acid value of 20 or less as a raw material, and there is little environmental impact because no wastewater treatment is required. Can also produce compatible biodiesel fuel.

  Hereinafter, preferred embodiments of the present invention will be described.

(Method for producing biodiesel fuel)
The method for producing biodiesel fuel according to the present invention uses oils and fats having an acid value of 20 or less as a raw material. Any oils and fats may be used as long as the acid value is 20 or less. For example, rapeseed oil, soybean oil, palm oil, palm kernel oil, sunflower oil, rice oil, sesame oil, corn oil, coconut oil, safflower oil , Vegetable oils such as safflower oil, peanut oil, cottonseed oil, flaxseed oil, mustard oil, animal fats such as beef tallow, pork fat, whale oil, fish oil, and their degradation during the production process of waste cooking oil or animal and vegetable oils Oil etc. are mentioned. When the acid value exceeds 20, the free fatty acid component is contained in an amount of 10% or more, resulting in a decrease in production efficiency and a problem from the economical aspect. In addition, water or the like contained as an impurity does not matter even if it is mixed in, but it is preferable that it is appropriately determined within the range of common sense as a raw material for acceptance.

  The method for producing biodiesel fuel according to the present invention includes a step of heating raw oil under reduced pressure to distill off moisture, odorous substances and free fatty acids prior to the transesterification reaction, and a raw material after the distilling step. Contacting the oil with a hydrophilic adsorbent and adsorbing and removing the remaining free fatty acids and acidic substances.

  It is preferable to perform the said distillation process at 50-170 degreeC and 1-20 mmHg. If it is less than 50 ° C., the vapor pressure can hardly be secured and the removal efficiency is deteriorated, and if it exceeds 170 ° C., the unsaturated portion in the fatty acid site is denatured, which adversely affects the properties as biodiesel fuel oil. Further, in order to maintain a high vacuum state of less than 1 mmHg, the cost of the apparatus and the operation cost increase, and at a pressure exceeding 20 mmHg, almost all free fatty acids remain even if moisture can be removed.

  Here, the raw material oil can be heated, for example, by exchanging heat with water vapor in a heat exchanger. The heated raw material oil is preferable because it can increase the surface area by introducing it into the pressure reducer in a sprayed state, thereby increasing the evaporation rate of moisture, free fatty acids and the like. The raw material oil that has passed through this step can have, for example, a moisture value of 500 ppm or less, a free fatty acid amount of 5000 ppm or less, and an odorous substance of 500 ppm or less.

  In the adsorption removal step using the hydrophilic adsorbent, it is desirable to use at least one selected from activated alumina having a particle size of 0.1 μm to 10 μm, activated carbon subjected to basic treatment, and silica gel as the adsorbent. The adsorbent is preferably packed in a column and used, and the adsorbent may be a small amount of about 0.1% to 5.0% of the raw material oil to be treated. If it is less than 0.1%, acidic substances such as free fatty acids cannot be sufficiently removed to a predetermined amount. However, if it exceeds 5%, the amount of adsorbed raw material oil increases and the adsorbent itself affects the production cost. The feedstock oil that has passed through this column can be reduced, for example, to a free fatty acid content of 0.3% or less. In this amount, for example, when 1% of potassium hydroxide is used as a catalyst with respect to the raw material oil, the amount consumed as fatty acid soap is suppressed to less than 10% of the catalyst amount, and the resulting fatty acid soap is produced. Since the concentration in the reaction liquid is less than CMC (critical micelle concentration), most of the resulting soap is dissolved in the heavy liquid (glycerin layer) after specific gravity separation, reducing the amount of impurities in the light liquid and refining. Becomes easy. If this step is omitted and the reaction is carried out with the same amount of catalyst at a free fatty acid amount of 0.5%, more than 10% of the catalyst is consumed by conversion to soap, and the reaction conversion efficiency decreases, Since the concentration becomes higher than the CMC concentration, separation after the reaction becomes difficult, and further, the soap concentration in the light liquid also increases, so that purification becomes difficult.

  In the method for producing biodiesel fuel according to the present invention, the feedstock oil and alcohol are subsequently subjected to a transesterification reaction in the presence of an alkali catalyst.

  The alcohol to be reacted with the raw material oil is selected from at least one of methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, and t-butyl alcohol. The purity of the alcohol is desirably 99.5% or more.

  In addition, as the alkali catalyst, potassium basic catalysts such as potassium hydroxide, potassium carbonate, potassium alcoholate and the like are used. When compared with a sodium-based basic catalyst such as sodium hydroxide, for example, 19.8 equivalents of stoichiometric amount of 99.8% pure methanol is used as the alcohol, the catalyst amount is 1 wt% of the feedstock oil, and the water content is 0.1%. When transesterification was carried out at 64 ° C with a raw material oil of 05% and free fatty acid content of 0.3%, the time required to reach a conversion rate of 99% or more was less than 5 minutes with potassium hydroxide. Sodium hydroxide finally reached 97.5% after 2 hours, and the conversion rate did not improve thereafter. Also in the specific gravity separation of light and heavy liquids after the reaction, the interface clearly appeared in about 20 minutes with potassium hydroxide, whereas with sodium hydroxide, an emulsion that became cloudy in the vicinity of the interface even after 8 hours had passed. There was no clear interface. These phenomena are attributed to the low CMC of sodium soap compared to that of potassium soap as well as the difference in catalytic activity.

  In the method for producing biodiesel fuel according to the present invention, it is preferable to first prepare a catalyst-containing alcohol solution, and then mix and stir the raw material oil and the catalyst-containing alcohol solution. As a result, the transesterification reaction can be completed in a very short time.

  Here, the amount of the catalyst dissolved in the alcohol is preferably 0.5 to 2.0% by weight, more preferably 0.7 to 1.5% by weight, based on the raw material oil. The amount of alcohol added to the raw oil is preferably a stoichiometric amount of 1.05 to 1.25 molar equivalents, and more preferably 1.08 to 1.15 molar equivalents. The greater the amount of catalyst added, the better the conversion rate and conversion rate. However, when the amount exceeds the specified range, the equilibrium conversion rate becomes constant, and conversely, the soaping reaction tends to occur. Become. As the amount of alcohol added is within the predetermined range, both the conversion rate and the conversion rate are improved. However, when the amount exceeds the predetermined range, the equilibrium conversion rate becomes constant, and excess alcohol is wasted. Further, after completion of the reaction, the specific gravity of the heavy liquid glycerin layer in the specific gravity separation is reduced by the alcohol and the alcohol itself expresses the function of the surfactant, so that the specific gravity separation tends to be difficult.

  When preparing the catalyst-containing alcohol solution, in order to prevent alcohol from bumping due to local overheating due to the heat of dissolution of the catalyst, a predetermined amount of alcohol is first put into the dissolution tank, and the catalyst is stirred under sufficient stirring. It is preferable to add a small amount of each and dissolve it completely. In order to discharge the heat of dissolution, it is also preferable to flow cooling water through the cooling water jacket so that the system temperature is maintained below the alcohol boiling point.

  The reaction between the raw material oil and the alcohol is preferably carried out at 25 ° C. to 250 ° C., more preferably 50 ° C. to 100 ° C., and the pressure is preferably atmospheric pressure 0.1 MPa to 7.8 MPa, more preferably atmospheric pressure 0. The range is from 1 MPa to 2.0 MPa. Under this condition, the equilibrium conversion reaches 99.8% or more. Since the reaction between triglyceride and alcohol is a reversible reaction, it is necessary to set an optimal reaction temperature and pressure in order to maximize the equilibrium conversion. However, if the temperature is raised above the boiling point of the alcohol in order to increase the reaction rate, the reactor becomes a pressure vessel, which may be disadvantageous in terms of cost. Accordingly, the optimum temperature and pressure settings are near the boiling point of the alcohol used and within the range of normal pressure to 0.12 MPa. The reaction time should be set to the minimum necessary time. This is because the reaction is reversible as described above, and a side reaction occurs in which the produced fatty acid alkyl ester reacts with the remaining water to cause hydrolysis. Accordingly, the reaction time is optimally from 1 minute to 20 minutes.

The reaction product of the transesterification reaction between the raw material oil and the alcohol is a mixture containing fatty acid alkyl ester and glycerin as main components. These have densities of about 0.87 to 0.90 gcm ³ and 1.10 to 1.25 g / cm ³ , respectively, and are not so soluble in each other. By doing so, it is separated into a light liquid mainly composed of fatty acid alkyl ester and a heavy liquid mainly composed of glycerin. By performing neutralization and distillation treatment on the heavy liquid, glycerin can be obtained as a by-product. Since the light liquid part contains impurities such as a small amount of catalyst, fatty acid soap, unreacted alcohol, and odorous substance, further purification is performed.

  In the biodiesel fuel production method of the present invention, the light liquid component is purified by a non-aqueous method, that is, a method that does not include a washing step with water. Specifically, the light liquid component is adsorbed with a basic substance. A process of contacting with a solid adsorbent, a process of removing solid impurities by centrifugation, a process of removing low-boiling substances by heating under reduced pressure, and a process of removing solid impurities through a filter are performed. These processes are preferably performed in the order described, but are not limited to the order and may be appropriately changed.

  The treatment brought into contact with the solid adsorbent is a treatment using a solid basic substance adsorbent, and can be performed, for example, by passing through an adsorbent packed column for removing a basic substance. As the adsorbent, at least one selected from the group consisting of activated carbon, activated carbon fiber, activated clay, acid clay, bentonite, diatomaceous earth, activated alumina, molecular sieves and silica gel can be used. These adsorbents may be subjected to microwave treatment and heat treatment (150 ° C. to 700 ° C.) immediately before use. At this time, the particle diameter of the filler is preferably in the range of 0.01 mm to 1.0 mm. The smaller the particle size, the better the adsorption efficiency. However, if it is finer than this, the pressure loss during passage through the column is large and the passage time is long. If the particle size is 1.0 mm or more, a sufficient adsorption effect cannot be obtained. An amount of the filler of 0.5 wt% to 2.0 wt% is sufficient, but more filler may be filled. The used filler can be treated either by regeneration or disposal. The passage flow rate can be set to, for example, about 5 to 30 liters per minute. However, when performing solid-liquid centrifugation processing thereafter, the flow velocity may be adjusted according to the centrifugation processing capability. The potassium concentration of the light liquid component after the solid adsorbent treatment is, for example, 5 mg / kg or less. The liquid is neutral.

  Moreover, the process which removes a solid impurity etc. from a light liquid component by centrifugation is performed with the centrifuge for solid-liquid separation, for example. By this treatment, high specific gravity substances such as a filler of 1 μm or less and glycerin and glycerin derivatives remaining in a small amount are removed.

  In addition, when addition of additives such as a pour point depressant and an oxidation stabilizer is necessary, it is preferably added at this point by a static mixer or the like.

  Moreover, the process which heats a light liquid component under reduced pressure is performed for low-boiling-point substance removal, for example, is performed in the reduced pressure tower provided with functions, such as reduced pressure dehydration, deodorization, deoxidation. The pressure is preferably 1 to 100 mmHg, and the temperature is preferably 20 to 100 ° C. By this treatment, for example, the moisture in the light liquid is 0.02% or less, the amount of free fatty acid is 0.15% or less, the amount of alcohol is 0.1% or less, the solid substance is 0.005% or less, and the odor substance is 10 ppm or less. can do.

  Moreover, the process which removes solid impurities etc. through a filter can remove 1 micrometer or more microparticles | fine-particles and a condensed substance using a cartridge type filter etc., for example.

  The method for producing a biodiesel fuel of the present invention includes a step of specific gravity separation of water or an aqueous solution from raw material oil prior to the step of heating the raw material oil under reduced pressure to distill off moisture, odorous substances and free fatty acids, You may perform the process of removing a solid substance with a filter from the raw material oil after specific gravity separation. The specific gravity separation step is performed, for example, by standing for about 4 to 12 hours, and is preferably performed while heating as necessary in order to keep the raw material oil in a liquid state. As a result, fine solids, water, salts, high specific gravity organic matter, etc. contained in the feed oil can be precipitated and removed, and the water content in the feed oil should be, for example, 10000 ppm or less by removing supersaturated water. Can do. The filter removal step can be performed, for example, by passing a strainer equipped with a cartridge filter of mesh 100 to 1000. By this step, it becomes possible to further remove fine solids, and for example, the solid content can be 0.05% or less.

  In the method for producing biodiesel fuel of the present invention, it is preferable that all the steps described above are performed continuously. By preparing a plurality of apparatuses for performing the same process as necessary, it is possible to efficiently manufacture without wasted time.

  According to the method for producing biodiesel fuel according to the present invention, water, odorous substances and free fatty acids are removed from raw material oil as much as possible, and then transesterification is carried out in the presence of an alkali catalyst to remove the product after the reaction. Since it is refined by a water system, it is a high quality product that conforms to official biodiesel standards such as EN14214 and ASTM D6715 by transesterification with alcohol using a catalyst from degraded oils such as animal and vegetable oils and waste edible oils. Biodiesel fuel can be produced.

The biodiesel fuel that meets the reference values shown in EN14214 and ASTM D6715 has a density of 0.860-0.900 g / cm ³ , a kinematic viscosity of 3.5-5.0 mm ² / s, and a flash point> 120 ° C. Cetane number> 51, water content <500 ppm, acid value <0.5 mg KOH / g, alcohol content <0.20%, ester content> 96.5%, total glycerol content <0.25%, alkali metal content <5 mg / It means that it can be used as a diesel vehicle fuel. Furthermore, from 2007, the specification value will be more strictly defined as moisture <200 ppm, alcohol content <1000 ppm, acid value 0.3 mg KOH / g, ester> 98.5%. According to the method for producing fuel, if a feedstock having an acid value not exceeding 20 is used, diesel fuel that satisfies these standards can be obtained.

  Moreover, in the manufacturing method of the biodiesel fuel which concerns on this invention, glycerol can be obtained as a by-product from the heavy liquid component of the reaction product after transesterification. First, sulfuric acid or phosphoric acid is dropped into the heavy liquid component to neutralize the alkali catalyst. It is preferable that an acid corresponding to an equivalent mole of protons with respect to the alkali catalyst is added dropwise after diluting with 0.3 to 5 mole equivalents of water with respect to potassium atoms in the alkali catalyst. Moreover, since the temperature of the neutralization liquid rises by the heat of neutralization, it is preferable to carry out the reaction while cooling. After completion of dropping, for example, the mixture is stirred for 5 to 20 minutes, and then the stirring is stopped and the mixture is allowed to stand for 30 minutes. If crystals of potassium acid salt precipitate, they are filtered off and the resulting filtrate is distilled. For example, the distillation is preferably performed at 1 mmHg to 20 mmHg and 160 ° C to 190 ° C. At higher temperatures, glycerin will decompose. After the distillation, it is further separated by centrifugation into a light liquid mainly composed of fatty acid alkyl ester and a heavy liquid mainly composed of glycerin. Thereby, glycerin with a purity of 99% or more can be obtained. From the light liquid obtained by centrifugation, purification such as solid adsorbent treatment can be performed again to obtain biodiesel fuel.

(Biodiesel fuel production equipment)
Next, an example of a production apparatus capable of implementing the biodiesel fuel production method according to the present invention as described above will be described with reference to the drawings.

  As shown in FIG. 1, the biodiesel fuel oil production apparatus for carrying out the biodiesel fuel production method of the present invention comprises a pretreatment unit 1, dehydration, deodorization, deoxidation unit 2, acidic substance removal unit 3, and catalyst-containing An alcohol solution preparation unit 4, a mixing reaction unit 5, a liquid-liquid separation unit 6, a neutralization / distillation processing unit 7, a basic substance adsorption processing unit 8, a high specific gravity substance removal processing unit 9, a low boiling point substance removal processing unit 10, And the particulate / condensed material removal processing unit 11. The configuration of the pretreatment unit 1, dehydration, deodorization, deoxidation unit 2, and acidic substance removal unit 3 is shown in FIG. 2, the catalyst-containing alcohol solution preparation unit 4, the mixing reaction unit 5, and the liquid-liquid separation unit 6. The configuration is shown in FIG. 3, the basic substance adsorption processing unit 8, the high specific gravity material removal processing unit 9, the low boiling point material removal processing unit 10, and the particulate / condensed material removal processing unit 11 are shown in FIG. The configuration of the processing unit 7 is shown in FIG.

  As shown in FIG. 2, the pretreatment unit 1 includes a raw material oil receiving tank 13 having a stainless steel net of about 10 to 100 mesh at the receiving port, a raw material oil storage tank 14 having a tapered lower portion, and a liquid-liquid. A centrifuge 15 and a strainer 17 with a cartridge filter are provided. The raw material oil is first fed into the raw material oil receiving tank 13 through a stainless steel net having 10 to 100 meshes. At this time, relatively large solid substances contained in the waste cooking oil or the like are removed by the mesh. The raw oil receiving tank is provided with steam or heating wire that can be heated to about 50 ° C, and it is liquid even in cold season operations of 0 ° C or less and oils and fats with a high freezing point such as palm oil and animal fat. It is possible to handle with.

  Then, it is sent into the raw material oil storage tank 14 via a liquid feed pump. In the raw material oil storage tank 14, it is left still for about 4 hours to 12 hours. As a result, fine solids, moisture, salts, high specific gravity organic matter and the like contained in the raw material oil are precipitated and removed from the lower drain valve. By removing supersaturated water by this physical specific gravity separation, the moisture value in the feedstock can be reduced to, for example, 10,000 ppm or less. The removed supernatant is passed through the strainer 17 and sent to the dehydration, deodorization and deoxidation unit 2. In order to perform the operation of the pretreatment unit 1 continuously, as shown in FIG. 2, a plurality of raw oil storage tanks 14 are prepared, and the liquid can be continuously sent to the next process in consideration of the standing time. It is preferable. Furthermore, in order to adjust the original property value of the oil type that affects the properties of the biodiesel fuel, such as iodine value and average molecular weight, it can also be suitably used when mixing different oil types. The raw oil storage tank 14 is provided with steam or heating wires that can be heated to about 50 ° C. As a result, oils and fats having a high freezing point such as cold season operation, palm oil and fat, and animal oil and fat can be handled in a liquid state.

  Further, a centrifuge 15 is provided in order to continuously feed the raw material oil to the next step. Thereby, since a stationary effect, that is, removal of a minute solid content, moisture, salt, and a high specific gravity organic substance can be obtained in a short time, it is possible to carry out the process further continuously. The raw material oil subjected to the primary treatment in this way can be further removed by passing through a strainer 17 equipped with a cartridge filter of mesh 100 to 1000, for example, a solid content of 0.05% or less. A pretreated feedstock is obtained.

  The dehydration, deodorization, and deoxidation unit 2 includes a steam generating boiler 19 that can use biodiesel fuel oil and glycerin as fuel, a multi-tube heat exchanger 18, a vacuum dehydration, deodorization, a deoxidation tower 20, a condenser 22, and A vacuum pump 23 is provided.

  The raw material oil from which the solid substance has been removed in the pretreatment section 1 is sent to the multitubular heat exchanger 18 by a liquid feed pump, and exchanges heat with water vapor while passing through the multitubular heat exchanger 18. The vacuum dehydration, deodorization, and deoxidation tower 20 are heated to the temperature required. The heated raw material oil is sprayed into the tower through a dispersion nozzle provided in the vacuum dehydration, deodorization and deoxidation tower 20. Further, the sprayed raw material oil passes in the form of a thin film on a plurality of fin-like perforated plates similarly installed in the tower. That is, at a temperature of 20 mmHg or less and a temperature of 50 ° C. to 170 ° C., moisture, odor components, and free fatty acids rapidly evaporate in a state where the surface area is increased by the effect of spraying and perforated plate, and discharged from the upper outlet of the tower 20. After that, it is liquefied by the condenser 22 and removed from the system. As a result, the raw oil is dehydrated, deodorized and deoxidized so that the water content is 0.05% or less, the odorous substance 0.05% or less, and the free fatty acid content 0.5% or less.

  The acidic substance removal processing unit 3 includes a solid hydrophilic adsorbent packed column 21. Acidic substances such as free fatty acids in the raw oil that has passed through the vacuum dehydration, deodorization, and deoxidation tower 20 are further adsorbed and removed by a hydrophilic and basic solid adsorbent. Under the conditions of reduced pressure dehydration, deodorization, and deoxidation tower 20 set to prevent thermal degradation of fatty acid sites, only a part of C18 and higher free fatty acids can be removed, so the total free fatty acid amount is up to about 0.5%. However, these free fatty acids can also be removed by passing through the acidic substance removal processing unit 3, and the amount of free fatty acids can be reduced to 0.3% or less. In this amount, for example, when 1% of potassium hydroxide is used as a catalyst with respect to the raw material oil, the amount consumed as fatty acid soap is suppressed to less than 10% of the catalyst amount, and the resulting fatty acid soap is produced. Since the concentration in the reaction liquid is less than CMC (critical micelle concentration), most of the resulting soap is dissolved in the heavy liquid (glycerin layer) after specific gravity separation, reducing the amount of impurities in the light liquid and refining. Becomes easy. For example, when this step is omitted and the reaction is performed with the same amount of catalyst at a free fatty acid amount of 0.5%, 10% or more of the catalyst is consumed by conversion to soap, and the reaction conversion efficiency is reduced. Since it becomes CMC concentration or more, separation after the reaction becomes difficult, and further, the soap concentration in the light liquid increases, so that purification becomes difficult.

  As shown in FIG. 3, the catalyst-containing alcohol solution preparation unit 4 includes a catalyst dissolving tank 27 and an alcohol storage tank 29 having a cooling water jacket. The preparation of the catalyst-containing alcohol solution is performed in a batch format according to the transesterification reaction. First, a predetermined amount of alcohol is fed from the alcohol storage tank into the catalyst dissolution tank 27 by the liquid feed pump 16. Next, while stirring this, a predetermined amount of potassium catalyst is introduced through the shooter at the top of the dissolution tank and stirred until it is completely dissolved. Since heat of dissolution is generated at this time, it is preferable to flow cooling water through a cooling water jacket so that the system does not exceed 65 ° C. By dissolving the catalyst in alcohol in advance, the transesterification reaction with the raw material oil can be completed in an extremely short time. When alcohol and a catalyst are directly added to a raw material oil and reacted without preparing a catalyst-containing alcohol solution in advance, the 96% exchange rate arrival time is 30 minutes, and finally 98.5%. It only took 2 hours to reach the conversion rate.

  The mixing reaction unit 5 includes a stirring reaction tank 24 including a stirring motor 25 and a stirring blade 26. The stirring reaction tank 24 is a cylindrical reactor, and a stirring blade 26 is attached to a rotating shaft installed at the center. By stirring the rotating shaft at a predetermined speed with the stirring motor 25, the raw material oil and the catalyst-containing alcohol can be brought into contact and reacted promptly. Furthermore, in order to adjust the reaction temperature to a predetermined temperature of 50 to 65 ° C., the stirred reaction vessel is equipped with a jacket, a heater and the like that can be cooled and heated. Further, two or more stirring reaction tanks 24 may be provided so that the subsequent steps are continuous, and the reaction may be performed sequentially and alternately. Since the time required for the entire reaction is 30 minutes or less, even one can maintain continuity.

  The liquid-liquid separation unit 6 includes a stationary specific gravity separation tank 30 and a liquid-liquid separation centrifuge 40. The reaction solution after completion of the reaction is sent to the stationary specific gravity separation tank 30 while maintaining a temperature of 50 ° C. or higher, and left to stand for 2 to 8 hours, and returned to room temperature (15 to 25 ° C.). As a result, the light liquid part (fatty acid alkyl ester liquid part) and the heavy liquid part (glycerin liquid part) are separated. The stationary specific gravity separation tank 30 is provided with a transparent window at a predetermined position so that the liquid-liquid interface can be confirmed. After this interface clearly appears, the heavy liquid is extracted from the drain at the bottom of the stationary specific gravity separation tank 30. The drain cock can be opened and closed manually by visual observation of the liquid state, but is automatically controlled by an interface sensor. The heavy liquid is sent to the neutralization / distillation processing unit 7. After extracting the heavy liquid, the light liquid part is sent to the basic substance adsorption processing part 8. In order to perform the process continuously, a plurality of separation layers 30 may be provided, and the reaction product is directly introduced into the liquid-liquid separation centrifuge 40 from the agitation tank 24 and separated into light liquid and heavy liquid. It is also possible to do.

  As shown in FIG. 4, the basic substance adsorption processing unit 8 includes an adsorbent loading column 31 for removing a basic substance. While the light liquid sent from the liquid-liquid separation unit 6 passes through the column 31, basic substances such as fatty acid soap and alkali catalyst contained therein are removed by adsorption. Furthermore, a part of hydrophilic substances such as water, glycerin and coloring substances remaining in a trace amount are removed. It is preferable to prepare a plurality of columns 31 so that the work can be continuously performed even when the filler is replaced. The used filler is treated by either regeneration or disposal. The passage flow rate can be adjusted according to the adsorption effect and the speed of the subsequent treatment, but is preferably about 5 to 30 liters per minute. Even higher speeds can be achieved by parallel use of buffer tanks and centrifuges.

The high specific gravity substance removal processing unit 9 includes a solid-liquid, liquid-liquid separation centrifuge 41. A centrifuge is used to remove a small amount of fine-grained adsorbent component (solid), water, glycerin and glycerin derivatives and other high specific gravity substances having a specific gravity of 1 g / cm ³ or more contained in the light liquid that has passed through the basic substance adsorption processing unit 41 to separate and remove.

  The low boiling point substance removal processing unit 10 includes a static mixer type additive introduction machine 45, vacuum dehydration, deodorization, deoxidation tower 44, condenser 42, and vacuum pump 43. The light liquid that has passed through the high specific gravity substance removal processing unit 9 is supplied with an additive such as a pour point depressant, if necessary, by a static mixer type additive introduction machine 45 before dehydration, deodorization, and deoxidation tower 44 under reduced pressure. Added. Thereafter, the light liquid is introduced into the vacuum dehydration, deodorization and deoxidation tower 44. Here, the low-boiling point substance is removed under conditions of 20 to 100 ° C. and 1 to 100 mmHg. As a result, alcohol, moisture, odorous substances and the like are removed. Furthermore, additives and the like can be dissolved uniformly.

  The particulate / condensed substance removal processing unit 11 includes a cartridge type filter 32 and a cartridge type filter 33. The filter 32 is equipped with a 5 μm filter, and the filter 33 is equipped with a 1 μm filter. Condensed substances of 1 μm or more can be removed by sequentially passing through the filter 32. After passing through the filter, it is transferred to the product tank.

  As shown in FIG. 5, the neutralization / distillation processing unit 7 includes a neutralization stirring tank 46, a dilute sulfuric acid storage tank 35, a continuous filter 36, a vacuum distillation tower 47, a boiler 51, a condenser 48, a vacuum pump 49, A liquid-liquid centrifuge 50 and a glycerin storage tank 52 are provided. The heavy liquid sent from the liquid-liquid separation unit 6 is first put into the neutralization stirring tank 46. To this, the acid stored in the dilute acid storage tank 35 corresponding to the equivalent mole of proton to the alkali catalyst used is diluted with 0.3 to 5 mole equivalent of water with respect to the potassium atom in the alkali catalyst, The solution is dropped and neutralized while stirring by the stirring motor 53. At this time, the temperature of the neutralizing solution rises due to the heat of neutralization, but is adjusted to 100 ° C. or lower, preferably 60 ° C. or lower, with cooling water. Stir for 5 to 20 minutes after the end of dropping, then stop stirring and leave for about 30 minutes. At this time, if a predetermined amount of water is not contained, crystals of the potassium salt do not grow, and the solution becomes a slurry and it is difficult to separate the next step. After confirming the formation of potassium salt crystals, the entire liquid is passed through the continuous filter 36 from the lower drain valve. The filtrate is introduced into the vacuum distillation tower 47 and subjected to vacuum distillation. The distillation is preferably performed at 1 mmHg to 20 mmHg and 160 ° C to 190 ° C. The main distillate is condensed in a condenser 48, and this is subjected to a liquid-liquid centrifuge 50 to be separated into a light liquid (fatty acid alkyl ester) and a heavy liquid (glycerin).

  The light liquid can be returned to the basic substance adsorption processing unit 8 and commercialized. The heavy liquid is transferred to the glycerin storage tank 52.

  Hereinafter, the production method of the present biodiesel fuel oil will be described with reference to more specific examples.

[Example 1]
In the manufacturing apparatus having the processing capacity of 20 tons / day configured as shown in FIGS. 1 to 5, a stainless steel net having 120 meshes was used as a filter attached to the receiving port of the raw material oil receiving tank 13. As a filter attached to the raw oil storage tank 14 or the strainer 17 installed on the outlet side of the solid-liquid / liquid-liquid centrifuge 15, a polyester long fiber made of 300 meshes was used.

  Used waste cooking oil (acid value: 5.2, iodine value: 108, flash point 230 ° C, moisture 1.1%) used in restaurants, etc. was received in the feed oil receiving tank 13 and sent to the feed oil storage tank 14. After this raw material oil was allowed to settle naturally for 8 hours, the supernatant was used in the subsequent steps. Potassium hydroxide (purity 90%) was used as a catalyst, and the catalyst was dissolved in a catalyst dissolving tank 27 at a ratio of 8.3 parts by weight of potassium hydroxide to 100 parts by weight of methyl alcohol (purity 99.8%). The adsorbent for light liquid purification was activated clay, and an average particle size of 0.1 mm was used. Sulfuric acid was used for neutralization of the heavy liquid.

  From the raw material oil storage tank 14, the raw material oil was heated to 150 ° C. through the strainer 17, the liquid feed pump 16, and the multitubular heat exchanger 18. This was sent to dehydration, deodorization and deoxidation tower 20 under reduced pressure. The liquid feeding speed was 20 kg / min. The absolute pressure of the vacuum tower 20 was 5 mmHg. The acid value at this time was 3.1. As the filler for the solid hydrophilic adsorbent-loaded column 21, activated alumina (average particle size 0.1 mm, equivalent to 1% by weight with respect to the passing raw material oil) was used. The passage speed was 25 kg / min, and the temperature of the raw material oil during passage was 80 ° C. The acid value at this time was 0.6. 1000 kg was fed into the stirring reaction tank 24 while confirming the mass with a liquid feed pump.

  The temperature of the raw material oil in the reaction vessel 24 was lowered to 64 ° C., and the catalyst solution was added with a methanol amount (121 kg, 1.1 equivalents) and a catalyst amount (10 kg, 1% by weight / raw material oil). The dropping time was 15 minutes. After completion of dropping, the reaction solution was stirred for 15 minutes. The stirring speed was 360 rpm. The reaction solution was extracted from the lower drain cock of the stirring reaction tank 24 and sent to the stationary specific gravity separation tank 30. Here, the reaction mixture was allowed to stand for 4 hours. The lower part of the generated interface, that is, the heavy liquid part of glycerin main component was extracted from 30 drains and sent to the neutralization / distillation treatment part. After extracting the heavy liquid part, the light liquid part was sent to the basic substance adsorption treatment part 8. The adsorbent packed column 31 for removing the basic substance was packed with activated carbon and activated clay in a multilayer structure. These amounts were 1% of the total flow through. The passing speed was 20 liters / minute. The light liquid after passing through the column was passed through a centrifuge 41 for solid-liquid separation at a speed of 20 liters / minute. The centrifugal effect at this time was performed at a rotational speed equivalent to 1,000 G. The light liquid after passing through the centrifugal separator was fed into a vacuum dehydration, deodorization and deoxidation tower 44 for removing low-boiling substances, and processed at a vacuum degree of 10 mmHg and a liquid residence time of 30 ° C. for 30 minutes. After the treatment, the light liquid was passed through the filters 32 and 33 to the product tank.

  The purity of the obtained light liquid, ie, biodiesel fuel, was measured using a capillary gas chromatograph (GC-14A, TC-1, 0.25mmID, 15m), inlet temperature: 280 ° C, detection temperature: 250 ° C, column The analysis was performed at a temperature of 40 ° C. for 5 minutes to 320 ° C. for 15 minutes, a temperature increase rate of 10 ° C./minute, a sample injection amount: 5 microliters, and the retention time was determined from the peak area from 16 minutes to 30 minutes. The structure of these peaks was confirmed by GC-MS in advance. At the same time, the amount of residual alcohol and other volatile substances were also determined from the peak areas. Water was also stopped with a Karl Fischer moisture meter. Density (15 ° C): [0.85-0.9g / cm3], Kinematic viscosity (40 ° C): [1.9-6.0mm2 / s], 95% distillation temperature: [360 ° C or less], Flash point: [100 ° C or more ], Clogging point: [0 to -20 ° C (Pour point: 0 to -20 ° C)], Sulfur content: [200ppm or less], Residual carbon: [0.05% or less (10% Residual carbon of residual oil: 0.5%) )], Cetane number: [> 51], iodine number: [120 or less], highly unsaturated fatty acid (C18: 3 or more) amount: [15% or less], phosphorus amount: [20 mg / kg] (inside []) Is described by a method defined in JIS standard and a normal method. The results are shown in Table 1. The conversion rate (Conversion%) in the table was calculated by the following formula. Moreover, the conversion rate in a table | surface contains the light liquid quantity collect | recovered at the time of heavy liquid refinement | purification.

Conversion rate = Amount of fatty acid alkyl ester produced / Amount to be added to the stirring reaction tank The heavy liquid after the liquid-liquid separation was sent to the neutralization / distillation processing unit 7 and neutralized under the following conditions.

Neutralizing agent: Diluted sulfuric acid consisting of 8.0 kg of concentrated sulfuric acid + 8.7 kg of water
Stirring time: 10 minutes, then left still for 30 minutes Temperature: 50 ° C
The reaction mixture (crystal-containing) was sent to the continuous filter 36 from the lower drain. The liquid feeding speed was 10 liters / minute. After filtering the potassium sulfate salt crystals, the obtained filtrate was introduced into a vacuum distillation column 47 and distilled. The degree of vacuum in distillation was 10 mmHg and the bottom temperature was 180 ° C. After removing the initial fraction containing some water, the main fraction is condensed with a condenser 48, and this is subjected to a liquid-liquid centrifuge 50 to separate into light liquid of fatty acid alkyl ester main component and heavy liquid of glycerin main component. did. The heavy liquid was fed to the glycerin storage tank 52 as product glycerin. The obtained light liquid was 24 kg. This was sent again to the basic substance adsorption treatment unit 8 and purified as biodiesel fuel. BDF after independent purification was 23.8 kg. The purity of glycerin obtained from the heavy liquid was 99.0%, and the amount thereof was 150 kg (yield from reaction raw material oil: 95.5%).

[Example 2]
It was carried out in the same manner as in Example 1 except that rapeseed oil (acid value: 0.6, iodine value: 118, flash point 230 ° C., moisture 0.2%) was used as the raw material oil. The results of property analysis are shown in Table 1.

[Example 3]
The same procedure as in Example 1 was performed except that soybean oil (acid value: 0.6, iodine value: 132, flash point 240 ° C., moisture 0.2%) was used as the raw material oil. The results of property analysis are shown in Table 1.

[Example 4]
The same procedure as in Example 1 was performed except that palm oil (acid value: 0.8, iodine value: 54, flash point 230 ° C., moisture 0.3%) was used as the raw material oil. The results of property analysis are shown in Table 1.

[Example 5]
From the raw material oil receiving tank 13, the raw material oil storage tank 14 was not allowed to stand for 8 hours, but was directly fed to the liquid-liquid centrifuge 15 for separation operation. The temperature of the raw material oil at this time was 55 ° C. Then passed to strainer 17. The flow rate was 15 liters / minute. As a result, the time from receiving the raw material to the reaction process was shortened to 1 hour 30 minutes. Except for this, the same procedure as in Example 1 was performed. The results of property analysis are shown in Table 2.

[Example 6]
In the liquid-liquid separation unit 6, the reaction mixture was passed directly from the reaction tank 24 to the liquid-liquid separation centrifuge 40. The temperature of the mixed solution at the time of passage was 40 ° C. The passing speed was 15 liters / minute. This shortened the residence time of the liquid-liquid separation part to 1 hour 30 minutes. Except this, the same procedure as in Example 1 was performed. The results of property analysis are shown in Table 2.

[Example 7]
Between the high specific gravity substance removal treatment part 9 and the low boiling point substance removal treatment part 10, 2,000 ppm of an acrylic polymer (molecular weight 100,000) pour point depressant was added by a static mixer. Except this, the same procedure as in Example 1 was performed. The results of property analysis are shown in Table 2.

[Example 8]
Ethyl alcohol (purity 99.5%) was used as the alcohol. At this time, the reaction temperature was 75 ° C. Except for this, the same procedure as in Example 1 was performed. The results of property analysis are shown in Table 2.

[Comparative Example 1]
From the raw material oil storage tank 14, the raw material oil was heated to 100 ° C. through the strainer 17, the liquid feed pump 16, and the multitubular heat exchanger 18. This was sent to dehydration, deodorization and deoxidation tower 20 under reduced pressure. The liquid feeding speed was 20 kg / min. The absolute pressure of the vacuum tower 20 was 5 mmHg. 1000 kg of this raw material oil was fed into the stirred reaction tank 24 while confirming the mass with a liquid feed pump without passing through the solid hydrophilic adsorbent loaded column 21. The acid value of the raw material oil at this time was 3.1. Except this, the same procedure as in Example 1 was performed. The results of property analysis are shown in Table 3.

[Comparative Example 2]
From the raw oil storage tank 14, the raw oil was heated to 200 ° C. through the strainer 17, the liquid feed pump 16, and the multitubular heat exchanger 18. This was sent to dehydration, deodorization and deoxidation tower 20 under reduced pressure. The liquid feeding speed was 20 kg / min. The absolute pressure of the vacuum tower 20 was 5 mmHg. 1000 kg of this raw material oil was fed into the stirred reaction tank 24 while confirming the mass with a liquid feed pump without passing through the solid hydrophilic adsorbent loaded column 21. The acid value of the raw material oil at this time was 0.8. Except this, the same procedure as in Example 1 was performed. The results of property analysis are shown in Table 3.

[Comparative Example 3]
Instead of the potassium hydroxide used in Example 1, sodium hydroxide (96.0% purity) was used, and in the catalyst dissolution tank 27, the catalyst was 11.5 parts by weight with respect to 100 parts by weight of methanol (purity 99.8%). This was dissolved at a ratio of 1 to a predetermined amount of raw material oil and reacted. Except for this, the same procedure as in Example 1 was performed. The results of property analysis are shown in Table 3.

[Comparative Example 4]
The light liquid after the specific gravity separation was sent directly to the high specific gravity substance removal processing section 9 without passing through the basic substance removal adsorbent packed column 31 of the basic substance adsorption processing section 8. Except this, the same procedure as in Example 1 was performed. The results of property analysis are shown in Table 4.

[Comparative Example 5]
The treatment was carried out without passing through the low boiling point substance removal treatment section 10. Except this, the same procedure as in Example 1 was performed. The results of property analysis are shown in Table 4.

[Comparative Example 6]
As a raw material oil, waste cooking oil (acid value: 30, iodine value: 75, water content: 3.3%) that has undergone very high oxidative degradation was used. The treatment conditions in the deodorization, dehydration and deoxidation section 2 under reduced pressure deodorization, dehydration and deoxidation tower 20 were 100 ° C. and 3 mmHg, and the flow rate was 10 liters / minute. Except this, the same procedure as in Example 1 was performed. The results of property analysis are shown in Table 4.

[Comparative Example 7]
When neutralizing the heavy liquid generated in the liquid-liquid separator 6, neutralization was performed by adding a predetermined amount of neutralized sulfuric acid (96% or more) without diluting the sulfuric acid with a predetermined amount of water. . At this time, in the mixed solution after neutralization, the potassium sulfate salt was not separated from the system, and was distributed throughout the solution to become a very viscous slurry. When this was sent as it was to the reduced pressure distillation column 37 and distilled, the yield of glycerin was 63%.

  As can be seen from the table, even when using deteriorated fats and oils whose values depending on the type of raw material oil such as pour point and iodine value do not satisfy the standard value, according to the production method according to the present invention, high values satisfying other standard values are obtained. It was confirmed that quality biodiesel fuel could be obtained.

It is a block diagram which shows an example of the apparatus for enforcing the manufacturing method of the biodiesel fuel oil which concerns on this invention. It is the schematic which shows the structure of the pre-processing part which comprises some manufacturing apparatuses shown in FIG. 1, dehydration, deodorizing, a deoxidation part, and an acidic substance removal process part. It is the schematic which shows the structure of the catalyst containing alcohol solution adjustment part which comprises a part of manufacturing apparatus shown in FIG. 1, a mixing reaction part, and a liquid-liquid separation part. It is the schematic which shows the structure of the basic substance adsorption process part which comprises some manufacturing apparatuses shown in FIG. 1, a high specific gravity substance removal process part, a low boiling point substance removal process part, and a microparticles | fine-particles / condensed substance removal process part. . It is the schematic which shows the structure of the neutralization and distillation process part which comprises some manufacturing apparatuses shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Pre-processing part, 2 ... Dehydration, deodorization, deoxidation part, 3 ... Acidic substance removal processing part, 4 ... Catalyst containing alcohol solution preparation part, 5 ... Mixing reaction part, 6 ... Liquid-liquid separation part, 7 ... Medium Summation / distillation processing unit, 8 ... basic material adsorption processing unit, 9 ... high specific gravity material removal processing unit, 10 ... low boiling point material removal processing unit, 11 ... particulate / condensed material removal processing unit, 13 ... feed oil receiving tank, 14 ... Raw oil storage tank, 15, 40, 41, 50 ... Centrifuge, 17 ... Strainer with cartridge filter, 18 ... Multi-tube heat exchanger, 19, 51 ... Boiler, 20 ... Vacuum dehydration, deodorization, deoxidation Tower, 21 ... Solid hydrophilic adsorbent-loaded column, 22, 42, 48 ... Condenser, 23, 43, 49 ... Vacuum pump, 24 ... Stirring reaction tank, 25, 53 ... Stirring motor, 26 ... Stirring blade, 27 ... Catalyst Dissolution tank, 29 ... Alcohol storage Tank, 30 ... Static gravity separation tank, 31 ... Adsorbent-loaded column for basic substance removal, 32, 33 ... Cartridge filter, 35 ... Diluted acid storage tank, 36 ... Continuous filter, 47 ... In a vacuum distillation column Japanese processing agitation tank, 45 ... Static mixer type additive introduction machine, 52 ... Glycerin storage tank

Claims (9)

A method for producing biodiesel fuel from a feedstock having an acid value of 20 or less,
Heating the raw oil under reduced pressure to distill off moisture, odorous substances and free fatty acids;
Contacting the raw material oil with a hydrophilic adsorbent to adsorb and remove remaining free fatty acids and acidic substances;
A step of transesterifying the raw oil and alcohol in the presence of at least one alkali catalyst selected from the group consisting of potassium hydroxide, potassium carbonate, and potassium alcoholate;
Separating a light liquid component from the reaction product of the transesterification reaction;
The light liquid component is contacted with a basic substance-adsorbing solid adsorbent, the solid impurities are removed by centrifugation, the low boiling point substance is removed by heating under reduced pressure, and the solid impurities are passed through a filter. A process for removing the like, and a process for producing biodiesel fuel.   The method for producing biodiesel fuel according to claim 1, wherein the hydrophilic adsorbent is at least one selected from the group consisting of activated alumina, basic treated activated carbon, and silica gel. The transesterification reaction step includes
A catalyst-containing alcohol solution is prepared by dissolving 0.5% to 2.0% by weight of the alkali catalyst in 1.05 to 1.25 molar equivalent of alcohol with respect to the fatty acid portion of the raw material oil. Adjusting the process,
The method for producing biodiesel fuel according to claim 1, comprising mixing and stirring the raw material oil and the catalyst-containing alcohol solution.   The method for producing biodiesel fuel according to any one of claims 1 to 3, wherein the step of separating the light liquid component is performed by centrifuging the reaction product.   The basic substance-adsorbing solid adsorbent is at least one selected from the group consisting of activated clay, acidic clay, activated carbon, bentonite, silica gel, activated alumina, and molecular sieves. The manufacturing method of the biodiesel fuel as described in a term.   6. The method according to claim 1, wherein a pour point depressant and an oxidation stabilizer are added to the light liquid before the light liquid component is heated under reduced pressure to remove a low boiling point substance. The manufacturing method of biodiesel fuel of description.   Prior to the distilling step, the method includes specific gravity separation of water or an aqueous solution from the raw material oil, and a step of removing a solid substance from the raw material oil after the specific gravity separation using a filter. The manufacturing method of the biodiesel fuel as described in a term.   The alcohol used for the transesterification is at least one selected from the group consisting of methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, and t-butyl alcohol. The manufacturing method of the biodiesel fuel of any one of 1-7. In the heavy liquid component after separation of the light liquid component from the reaction product, sulfuric acid or phosphoric acid corresponding to an equivalent mole of proton with respect to the alkali catalyst is added in an amount of 0.3 to 5 mol with respect to the potassium atom in the alkali catalyst. Diluting with an equivalent amount of water, adding and neutralizing;
A step of distilling the obtained inclusion hydrate or the filtrate after filtering the hydrated potassium sulfate crystal or the hydrated potassium phosphate crystal under reduced pressure to obtain glycerin as a by-product. The method for producing biodiesel fuel according to any one of 1 to 9.

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