JP2009298982A - Tank and method for liquid-liquid separation of crude biodiesel fuel from glycerol - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tank and a method for liquid-liquid separation of crude biodiesel fuel from glycerol, whereby a higher fatty acid ester can be separated from a by-product of glycerol. <P>SOLUTION: The tank 3 for liquid-liquid separation of a crude biodiesel fuel from glycerol by difference of specific gravity, is divided into an inner circle part 10 formed with an inner wall concentric with the outer wall, and a plurality of separation chambers 9a-9c formed between the outer wall and the inner wall 10. One partition plate 11 of the introduction separation chamber 9a is integrated with the bottom of the tank at the lower part, and is higher than the liquid face in the upper part so as to prevent the liquid from flowing out. Meanwhile, each of the other partition plates 12a, 12b formes a space by separating at a prescribed interval from the bottom of the tank in the lower part, and has the height lower than the liquid face in the upper part. The final separation chamber 9c in a flowing direction of a reaction mixture, communicates with the inner circle part 10 in the lower part, and has an outlet 13 for taking out the crude biodiesel fuel at the upper part. The inner circle part 10 has an outlet 15 at the bottom to discharge the glycerol. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a liquid-liquid separation tank for biodiesel fuel and glycerin, which is a light oil alternative fuel prepared from raw oils and fats such as vegetable oil, animal oil, and waste oil, and a liquid-liquid separation method thereof.

  In recent years, production of biodiesel fuel (hereinafter referred to as BDF), which is a higher fatty acid ester, from raw oils and fats such as vegetable oil (rapeseed oil, soybean oil, etc.), animal oil, waste oil (waste edible oil, etc.), has become popular worldwide Has been done.

  Several methods are known as conventional methods for producing BDF, but comparison is made between about 50 ° C. and about 65 ° C. under atmospheric pressure in that the reaction rate is high and the handling of the reactor is relatively simple. The phase-homogeneous alkali method, in which a catalyst alkali is added under a mild reaction condition to cause a transesterification reaction with an alcohol, is most widely used as a de facto world standard.

  In this BDF production method, it is necessary to separate the crude BDF produced after the transesterification reaction and the glycerin produced as a by-product, and as such a separation method, a method utilizing a difference in specific gravity, that is, by allowing it to stand. A method is generally employed in which glycerin having a high specific gravity is separated at the bottom and crude BDF having a low specific gravity is separated at the top and then each is extracted.

  For example, Patent Document 1 discloses a method of performing specific gravity separation while decelerating a flow of a reaction mixture containing a fatty acid ester as a reaction target, glycerin as a byproduct, and alcohol as a residue after a transesterification reaction in a high temperature range. A method and apparatus are described that can reduce production costs by continuously and automatically separating glycerin and higher fatty acid esters by means of a separator with a channel.

  Patent Document 2 describes a method and an apparatus for separating glycerin from higher fatty acid ester by allowing a reaction mixture containing higher fatty acid ester and glycerin as fuel to stand.

Further, Patent Document 3 describes an oil-water separation tank having a box-type structure including a plurality of separation tanks in which the objects to be separated are oil and water.
Japanese Patent Laid-Open No. 10-182518 JP 2001-98284 A Japanese Patent Laid-Open No. 2005-219047

  In the conventional separation method and apparatus represented by Patent Documents 1 and 2, the structure for making the separation more rapid has not been studied in detail. Moreover, since the apparatus of the cited reference 3 is the oil and water with which there is almost no interaction, it has an interaction, and furthermore, it cannot be applied as it is to the separation of BDF and glycerol containing methanol. .

  An object of the present invention is to provide a liquid-liquid separation tank of crude BDF and glycerin and a liquid-liquid separation method thereof that can more efficiently separate a higher fatty acid ester as BDF and glycerin as a by-product. To do.

In order to solve the above problems, the present invention provides:
A tank for liquid-liquid separation of crude BDF and glycerin by a specific gravity difference from a reaction mixture from a biodiesel production process for obtaining BDF by transesterification of raw oil and alcohol,
The tank includes an inner circle portion formed by an inner wall concentric with a vertical cylindrical outer wall, and three or more vertical partition plates extending radially in a space formed between the outer wall and the inner wall. It is divided into a plurality of separation chambers formed by partitioning,
Among the plurality of separation chambers, one separation chamber is an introduction separation chamber, and one partition plate of the introduction separation chamber has a lower portion integrated with a tank bottom so that liquid does not flow out, and an upper portion is a liquid separation chamber. The other partition plates are spaced apart from the bottom of the tank at a required interval at the required interval, and the upper portion is lower than the liquid level.
The reaction mixture sequentially passes through the adjacent separation chambers in one direction through the upper and lower portions of each partition plate forming the gap from the introduction separation chamber,
The final separation chamber in the flow direction communicates with the inner circle at the lower part and has a discharge port for taking out the crude BDF at the upper part, and the inner circle discharges glycerin at the bottom. A liquid-liquid separation tank for crude BDF and glycerin is provided.

  On the upper side of the separation tank, it is preferable that a reactor for performing the biodiesel production process is provided concentrically and integrally with the separation tank.

  The liquid-liquid separation pressure is preferably normal pressure.

  When the reaction mixture sequentially passes through the adjacent separation chamber from the introduction separation chamber, the liquid-liquid separation is promoted by colliding with each partition plate, and the crude BDF and glycerin can be efficiently separated.

  In addition, since the transesterification reaction is an equilibrium reaction, the reaction rate decreases when the amount of by-product of glycerin increases, and the reaction does not proceed further when a certain concentration is reached. Since the tank separates glycerin produced as a by-product while moving the reaction mixture, it is possible to promote the progress of the reaction during the movement.

  Further, since the separation tank of the present invention has a concentric circular structure, it can be made more compact than a box-type structure, and furthermore, it becomes difficult to form a fluid retention zone. Can be promoted. The separation target of the present invention is an ester having an interaction and glycerin, and further contains an alcohol, so that the ester and glycerin are mutually dissolved and hardly decomposed. Since the separation tank of the present invention has a concentric structure in which such a residence zone is unlikely to occur, the separation of these substances can be made more efficient.

  Hereinafter, the liquid-liquid separation tank and the liquid-liquid separation method of crude BDF and glycerin according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a flow sheet for explaining a transesterification reaction in the production of BDF according to the present invention.

  The raw fats and oils and alcohol used for the production of the BDF of the present invention are supplied to the pretreatment tower (1), where they are stirred so as to be uniform.

  The raw material mixture stored in the pretreatment tower (1) is introduced into a vertical cylindrical transesterification tower (2). A catalyst (KOH / methanol solution or the like) is added to the transesterification reaction column (2), and the mixture is stirred under a relatively mild reaction condition of 50 to 65 ° C. under atmospheric pressure to perform the transesterification reaction.

  In the present embodiment, a cylindrical liquid-liquid separation tank (3) having the same concentric diameter is integrally provided at the bottom of the transesterification reaction tower (2), and the mixture after the reaction is composed of crude BDF and glycerin. And separated.

  The crude BDF after separation is supplied to further purification means (not shown) for making BDF of high purity, and glycerin is supplied to the glycerin treatment tower (4).

  The raw oil / fat supplied to the pretreatment tower (1) is not particularly limited as long as it has a higher fatty acid ester group, and may be either a natural fat or a synthetic fat / oil, and a mixture thereof. But it ’s okay. Specific raw oils and fats that can be used include, for example, soybean oil, palm oil, palm oil, palm kernel oil, jatropha oil, corn oil, peanut oil, sunflower oil, olive oil, safflower oil, coconut oil, oak oil, Almond oil, black walnut oil, apricot seed oil, cocoa butter oil, safflower oil, safflower oil, China oil, flaxseed oil, cottonseed oil, rapeseed oil, vegetable oil such as tung oil, castor oil, cottonseed stearin, sesame oil, lard oil, Chicken oil, butter oil, cod liver oil, deer fat, dolphin oil, sardine oil, mackerel oil, horse fat, pork fat, bone oil, sheep fat, cow leg oil, murine dolphin oil, shark oil, sperm whale oil, whale oil, Examples thereof include animal fats such as beef tallow and beef bone fat, vegetable oils discarded from restaurants, food industries, general households, and the like.

  Said various fats and oils are used independently, In addition, what mixed multiple types among the said fats and oils may contain diglyceride and monoglyceride.

  Furthermore, the raw material fats and oils may be synthetic triglycerides containing synthesized triglycerides, monoglycerides and / or diglycerides, and modified by modification such as oxidation and reduction of some of these fats and oils. Fats and oils may be used. Moreover, the processed fats and oils which have these fats and oils as a main component can also be used as a raw material.

  The alcohol is not particularly limited as long as it is suitable for the transesterification reaction. For example, the saturated linear or branched hydrocarbon having 1 to 8 carbon atoms, preferably 1 to 5 carbon atoms. Examples include alcohols having a skeleton. Specific examples include methanol, ethanol, propanol, isopropanol, n-butanol, t-butanol, and the like. These alcohols can be used alone or in combination of a plurality of these. In the present invention, it is preferable to use methanol and / or ethanol from the viewpoint of availability and availability of the obtained fatty acid ester.

  FIG. 2 is a schematic view seen from the side showing a liquid-liquid separation tank of crude BDF and glycerin according to the present invention and a transesterification reaction tower provided integrally thereon, and FIG. It is a top view explaining the liquid-liquid separation tank of BDF and glycerol.

  The raw material mixture for the reaction of the pretreatment tower (1) is introduced into the transesterification reaction tower (2) via the conduit (5), and a catalyst for the transesterification reaction is supplied via the conduit (6). The

  The catalyst for the transesterification reaction is not particularly limited as long as it is basic. For example, alkali metal hydroxides such as potassium hydroxide, sodium hydroxide, lithium hydroxide, sodium methoxide, sodium Examples include alkali metal alkoxides such as ethoxide.

  At the bottom of the transesterification reaction tower (2), a stirring blade (7) is rotatably installed so as to sufficiently stir the raw material mixture and catalyst introduced into the reaction tower (2). .

  Here, in the present embodiment, the transesterification column (2) is provided with one tank for a single-stage reaction, but is not particularly limited to one for a single-stage reaction, and is for a multi-stage reaction. There may be.

  In addition, the reaction temperature here is not particularly limited as long as it is a temperature at which the transesterification reaction proceeds, but a higher temperature is preferable in order to increase the reaction rate. However, when the temperature is higher than the boiling point of the alcohols, it is necessary to perform the reaction in a pressurized state using a sealed container, resulting in an increase in cost. Therefore, the reaction is preferably performed at a temperature lower than the boiling point of the alcohols.

  The transesterification reaction tank (2) is provided with a reaction mixture discharge pipe (8) extending vertically through the bottom wall to the separation tank (3). The discharge pipe (8) is installed so that the upper end comes closer to the top of the reaction tank (2), and the reaction mixture overflows the upper end of the discharge pipe (8), so that the lower part is passed through the discharge pipe (8). Into the separation tank (3).

  In the present embodiment, the upper transesterification tower (2) and the lower separation tank (3) are cylindrical and concentrically concentric with each other. If comprised in this way, the integrated apparatus from transesterification to isolation | separation can be comprised, and the reaction product in the lower separation tank (3) from transesterification in an upper transesterification reaction tower (2) The steps up to separation can be carried out continuously.

  As shown in FIG. 3, the separation tank (3) has an inner circle portion (10) formed by a concentric inner wall with respect to a vertical cylindrical outer wall. In a space formed between the outer wall and the inner wall of the separation tank (3), three or more vertical partition plates (11, 12a, 12b) extending in the radial direction are provided, and the first separation chamber (9a ), A second separation chamber (9b) and a third separation chamber (9c).

  In the first separation chamber (9a), a discharge pipe (8) penetrating the bottom wall of the transesterification column (2) reaches the vicinity of the bottom of the transesterification column (9a). ) Is first introduced into the first separation chamber (9a). Therefore, the first separation chamber (9a) is the introduction separation chamber.

  At the lower end of the partition plate (11) that partitions the first separation chamber (9a) and the third separation chamber (9c), the reaction mixture introduced into the first separation chamber (9a) is the third separation chamber (9c). So that the reaction mixture does not flow into the same chamber (9c) from the top, higher than the other partition plates (12a, 12b), And it is installed higher than the liquid level.

  On the other hand, a partition plate (12a) that partitions the first separation chamber (9a) and the second separation chamber (9b) and a partition plate (12b) that partitions the second separation chamber (9b) and the third separation chamber (9c). The lower end of the reaction tank is set slightly apart from the bottom wall of the separation tank (3) so that the reaction mixture can pass through, preferably at an interval of about 1/10 of the liquid level of the reaction mixture. Has been. Moreover, each partition plate (12a) and (12b) is installed in the height lower than the liquid level of a reaction mixture so that a reaction mixture can distribute | circulate exceeding these. Thereby, the flow path of the reaction mixture is formed in the upper part and the lower part of each partition plate (12a, 12b).

  With such a configuration, the reaction mixture can pass through the first separation chamber (9a), the second separation chamber (9b), and the third separation chamber (9c) in this order, and is the final separation chamber in the flow direction. The third separation chamber (9c) has a lower opening (14) communicating with the inner circle at the lower part. Further, the third separation chamber (9c) has a BDF discharge port (13) for taking out the coarse BDF at the upper part thereof.

  The inner circle part (10) has a glycerin outlet (15) for discharging separated glycerin at the bottom.

  The reaction mixture introduced into the separation tank (3) through the discharge pipe (8) passes through each separation chamber in order from the first separation chamber (9a) to the third separation chamber (9c), In that case, by repeating collision with each partition plate (12a, 12b), it is efficiently separated into crude BDF and glycerin during the passage.

  In the present embodiment, the description has been given of the case in which three separation chambers are formed in the separation tank by three partition plates. However, the number of partition plates, and therefore the number of separation chambers, is the number of the present embodiment. For example, as shown in FIG. 4, four or five partition plates may be installed, or more partition plates may be used. In the present embodiment, the intervals between the partition plates are arranged so as to be equal, but may be made unequal so that the intervals are changed according to the degree of separation. Further, the design of the height of each partition plate and the opening of the bottom can be changed as appropriate.

  Hereinafter, the Example which actually isolate | separated the reaction mixture after transesterification using the separation tank of this invention is demonstrated.

(Example 1)
Transesterification and separation of crude BFD and glycerin after the reaction were performed using the apparatus having the configuration shown in FIGS. Specifically, a transesterification tower (2) having a height of about 350 mm was used, and a separation tank (3) having a height of about 300 mm was used. The inner diameters of the transesterification tower (2) and the separation tank (3) having the same concentric diameter were about 360 mm.

  Moreover, waste edible oil was used as the raw oil and fat, methanol was used as the alcohol, and potassium hydroxide was used as the catalyst.

  These reaction raw material mixtures were stirred in the transesterification reactor (2) at 60 ° C., and the reaction mixture was introduced into the separation tank (3) through the discharge pipe (8) so that the flow rate was about 640 mL / min. .

(Example 2)
The operation was performed in the same manner as in Example 1 except that the temperature of the transesterification column (2) was 50 ° C.

(Example 3)
The operation was performed in the same manner as in Example 1 except that the temperature of the transesterification column (2) was 65 ° C.

(Comparative Example 1)
The transesterification in the transesterification tower (2) was carried out in the same manner as in Example 1, but the reaction mixture after the reaction was separated by standing without using the separation tank of FIG. That is, in the separation tanks of FIGS. 2 and 3, the separation tank was allowed to stand and separate, and crude BDF was discharged from the BDF discharge port and glycerin was discharged from the glycerin discharge port.

  The concentrations (wt%) of crude BDF and glycerin according to Examples 1 to 3 and Comparative Example 1 are shown in Table 1 below.

  As shown in Table 1 above, in Comparative Example 1, the concentration of crude BDF was 75% by weight and the concentration of glycerin was only about 65% by weight, and the crude BDF and glycerin were separated at a high concentration as in Examples 1-3. I couldn't.

It is a flow sheet explaining transesterification in manufacture of crude BDF concerning the present invention. It is the schematic from the side which shows the liquid-liquid separation tank of the crude BDF and glycerol which concerns on this invention, and the transesterification tower provided in the upper part integrally with this. It is a horizontal sectional view explaining the liquid-liquid separation tank of rough BDF and glycerin. It is a top view which shows the other example of a liquid-liquid separation tank.

Explanation of symbols

(1) Pretreatment tower (2) Transesterification reaction tower (3) Separation tank (4) Glycerin treatment tower (5) (6) Conduit (7) Stirring blade (8) Discharge pipe (9a) First separation chamber (9b ) Second separation chamber (9c) Third separation chamber (10) Inner circle (11, 12a, 12b) Vertical partition plate (13) BDF outlet (14) Lower opening (15) Glycerin outlet

Claims (2)

A tank for liquid-liquid separation of crude biodiesel fuel and glycerin by a specific gravity difference from a reaction mixture from a biodiesel production process for obtaining BDF by transesterification of raw oil and alcohol,
The tank includes an inner circle portion formed by an inner wall concentric with a vertical cylindrical outer wall, and three or more vertical partition plates extending radially in a space formed between the outer wall and the inner wall. It is divided into a plurality of separation chambers formed by partitioning,
Among the plurality of separation chambers, one separation chamber is an introduction separation chamber, and one partition plate of the introduction separation chamber has a lower portion integrated with a tank bottom so that liquid does not flow out, and an upper portion is a liquid separation chamber. The other partition plates are spaced apart from the bottom of the tank at a required interval at the required interval, and the upper portion is lower than the liquid level.
The reaction mixture sequentially passes through the adjacent separation chambers in one direction through the upper and lower portions of each partition plate forming the gap from the introduction separation chamber,
The final separation chamber in the flow direction communicates with the inner circle part at the lower part, and has an outlet for taking out crude biodiesel fuel at the upper part, and the inner circle part is glycerin at the bottom part. A liquid-liquid separation tank for crude biodiesel fuel and glycerin, characterized by having a discharge port for discharging water.   The crude biodiesel fuel and glycerin liquid according to claim 1, wherein a reactor for performing the biodiesel production step is provided concentrically and integrally with the tank on the upper side of the separation tank. Liquid separation tank.

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