JP2006249066A - Method for enhancing efficiency of gas-liquid reaction - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low cost method for enhancing reaction efficiency having no problem in operation in a gas-liquid reaction, especially in a transesterification reaction of an oil and fat with an alcohol. <P>SOLUTION: The method for producing a useful product is, in a process in which a gas is blown into a liquid material in a reaction vessel and a useful product is prepared by the reaction between the liquid material and the gas, to generate the objective reaction or a part of the objective reaction mostly when bubbles of the gas are generated, destroyed, brought to be minute or disappeared. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a method for improving the efficiency of a reaction in a step of blowing a gas phase substance into a liquid phase substance and obtaining a useful product by a reaction between the two.

In the process of obtaining useful products by chemical reaction, the reaction efficiency is directly linked to productivity, so the improvement is always the attention of the concerned parties, and various measures are applied depending on the form of reaction. Is done. In the process of obtaining a desired product by the reaction between the two by injecting a gas phase substance into the liquid phase substance, a general method for improving the reaction efficiency is as follows. (B) Increase in gas-liquid contact area (c) Use of catalyst, and industrially, in most cases, these methods are used alone or in combination. Recently, in special cases, a method using (d) an increase in activity of a substance in a critical state has been attempted (for example, Patent Documents 1 to 5).

However, (a) an increase in the reaction temperature often involves a harmful side reaction in addition to an increase in energy cost, and (c) the use of a catalyst in addition to an increase in cost for catalyst replacement / regeneration, Consideration should be given to problems such as separation of mixed catalyst and disposal of waste catalyst. In addition, (d) a method using a critical state requires high pressure and high temperature, so that careful consideration for safety is indispensable as equipment costs increase.

(B) Since the increase in the gas-liquid contact area is relatively small in cost and does not adversely affect the reaction product, it is used in almost all cases, and generally increases in the gas-liquid contact area due to the miniaturization of bubbles. In addition, the installation of a structure for increasing the stirring, the stirring effect, and the gas-liquid contact path length has become common. The present inventors proceeded with the study on the transesterification reaction between fats and oils and alcohol. In addition to these, the liquid phase was made into a foam to further improve the gas-liquid contact efficiency, and at the same time, the amount of the gas phase substance as required A method was proposed to make the excess easily in excess of liquid substances. (Patent Document 6)

However, in the reaction between a gas in a bubble state and an external liquid, reaction product accumulates at the interface and inhibits the reaction. In some cases, diffusion of the reaction product becomes a rate-determining step of the reaction. The purpose cannot be achieved only by increasing the area, and when the reaction product is strongly adsorbed on the interface, the diffusion effect of the reaction product by stirring is limited.
JP2000-143586 JP2000-109883 JP 2000-204392 A JP 2001-302584 A JP2002-308825 Japanese Patent Application No. 2004-231676

In order to further improve the productivity of the transesterification reaction mainly between fats and fats and alcohols, the present inventors can solve the above problems and improve the reaction efficiency with high versatility without increasing costs. Try to develop a manufacturing method.

In the process of studying the transesterification reaction between oils and fats and alcohols, the present inventors have continued to observe the relationship between the behavior of alcohol bubbles in the oils and the surface of the oils and the reaction efficiency. It was found that increasing the number of alcohol bubbles generated and extinguished by the method would increase the reaction efficiency, and based on this, the following invention was made.
(1) In the process of blowing a gas into a liquid substance in a reaction vessel and obtaining a useful product by a reaction between the liquid substance and the gas, mainly at the time of generation / destruction or miniaturization / extinction of bubbles of the gas A method for producing a useful product, characterized by causing a target reaction or a part of a target reaction to occur in the method.
(2) The superheated vaporized alcohol is blown into the liquid fats and oils in the reaction vessel, a transesterification reaction is performed between the fine bubbled alcohol and the fats and oils, and the product is vaporized together with the excess superheated vaporized alcohol. A method for producing a fatty acid ester obtained in a phase state, characterized in that the transesterification reaction or a part of the transesterification reaction is caused mainly at the time of formation, destruction, or miniaturization / extinction of alcohol bubbles. Production method.
(3) In the manufacturing method according to (1) or (2), the gas pressure in the bubble by the sum of the surface tension or surface tension of the bubble and an external pressure is equal to or higher than the critical pressure or critical pressure of the gas. And a method for producing a fatty acid ester, particularly among useful products or useful products, characterized in that the gas temperature in the bubbles is a critical temperature of the gas or higher than the critical temperature.
(4) In the production method according to any one of (1) to (3), a useful product or a microbubble is destroyed or miniaturized / erased by irradiation with ultrasonic waves having a constant or variable frequency. Among the useful products, in particular, a method for producing a fatty acid ester.
(5) In the production method according to any one of (1) to (3), a useful production characterized in that a structure for producing / destroying or miniaturizing / extinguishing microbubbles is installed in the reaction vessel. Method of producing fatty acid ester among products or useful products.
(6) The method for producing a fatty acid ester, particularly among useful products or useful products, wherein the structure is a perforated plate.
(7) In the manufacturing method according to (5), the structure is a net-like material, or a lattice-like / honeycomb-like aggregate of slits or a ring-like filling formed of thin plates. A method for producing a fatty acid ester, particularly among useful products or useful products.
(8) In the production method according to (6) or (7), the pore size of the perforated plate or the fineness of the mesh of the perforated plate or the fineness of the aggregate of slits in the structure having the same structure or the same kind of structure A method for producing a fatty acid ester, particularly among useful products or useful products, wherein a plurality of products having different degrees are installed in series.
(9) In the production method according to (6) or (7), the structure is of a different structure, or the pore diameter of the perforated plate or the mesh fineness of the mesh or the fineness of the aggregate of the slits in the different structure. A method for producing a fatty acid ester, particularly among useful products or useful products, characterized in that a plurality of them are installed in series, including those of varying degrees.
(10) In the manufacturing method according to (8) or (9), a plurality of products having a change in the pore diameter of the perforated plate of the structure, the mesh fineness of the mesh, or the slit fineness of the aggregate of slits When installed in series, the liquid substance and bubbles are set so that the liquid particles and bubbles sequentially pass from the one having the larger pore size to the one having the smaller pore size, or the one having the fineness from the fineness of the mesh or the fineness of the slit passage. A useful product or a method for producing a fatty acid ester among useful products.
(11) When a plurality of perforated plates are installed in series, a plurality of baffle plates are used in combination to extend the passage of liquids and bubbles, among useful products or useful products Especially the manufacturing method of fatty acid ester.
(12) In the production method according to any one of (5) to (11), a mechanical vibration is imparted to the structure, and in particular, a production method of a fatty acid ester among useful products or useful products.
(13) In the production method according to any one of (5) to (12), the material of the structure is used for a reaction between the liquid substance and the gas, particularly for a transesterification reaction between an alcohol and an oil. A useful product or a method for producing a fatty acid ester among useful products, characterized by having a catalytic action.
(14) In the production method according to any one of (5) to (13), a draft tube is installed in the structure, and particularly a production method of a fatty acid ester among useful products or useful products.
(15) In the manufacturing method according to any one of (5) to (14), a structure for generating / destructing or miniaturizing / disappearing microbubbles or a mechanism of the structure and its accompanying draft tube (hereinafter referred to as a structure) A method for producing a fatty acid ester, particularly among useful products or useful products, characterized in that a plurality of reaction units (collectively referred to as reaction units) are installed in parallel in a reaction vessel.
(16) In the production method according to (15), one or a plurality of jackets are installed around the reaction unit, and the temperature in the reaction unit is controlled by circulating a heat medium in the jacket. Among the products or useful products, particularly a method for producing a fatty acid ester.
(17) In the production method according to any one of (5) to (16), a useful product or a useful product is characterized in that gas is blown through a porous sintered body made of metal or ceramics. Especially the manufacturing method of fatty acid ester among things.
(18) Any one of the production methods described in (5) to (17) is repeatedly used, or one or more of the production methods are combined with a gas-liquid reaction apparatus other than the production method to produce a multistage process A method for producing a fatty acid ester, particularly among useful products or useful products, characterized by constructing a reaction step.

According to the present invention, the reaction efficiency of the gas-liquid reaction, in particular the transesterification reaction between fats and oils and alcohol, is improved and the productivity is increased without particularly increasing the cost.

First Embodiment: As described in (1) and (2), the first embodiment generally generates / breaks or miniaturizes bubbles in response to a reaction in which a gas generally exists as a bubble in a liquid. -It promotes extinction and improves reaction efficiency. The reason for the improvement of the reaction efficiency by the generation, destruction, miniaturization, and disappearance of the bubbles found by the present inventors is not only the elimination of the accumulation of the reaction products described above, but also the interfacial energy associated with the collapse of the bubbles. In the case where the bubble diameter is less than a micron, it is said that extremely high energy is expressed locally with collapse. In addition, the pressure inside the bubble due to the interfacial tension increases rapidly as the bubble diameter decreases, so the solubility of the gas in the bubble increases and the gas inside the bubble decreases, which further reduces the bubble diameter. Therefore, if the refinement exceeds a certain limit, the bubbles rapidly shrink and disappear (Bubble Technology p.40: Tsuge et al., Industrial Research Council, 2004). It is thought that it contributes to improvement. Therefore, the method of causing a reaction at the time of destruction or miniaturization / disappearance of bubbles in the present invention is based on the facts found during the study of the transesterification reaction, but can be applied to a wider range. is there. However, there are many unclear elements in the details of the reaction mechanism, and the details are not preferred to be bound by any theory at present.

Second Embodiment: As described in (3), in the second embodiment, the gas pressure in the microbubbles is reduced at the time of destruction / extinction of the microbubbles or in the vicinity before the destruction / extinction. The reaction in the supercritical state is realized by setting the critical pressure or the critical pressure or higher and setting the gas temperature in the microbubbles to the critical temperature or the critical temperature of the gas or higher. As described above, the pressure in the bubbles rapidly increases with a decrease in the bubble diameter, and exceeds the critical pressure in a gas that is a normal reaction element, such as superheated alcohol. At this time, if the temperature of the gas is equal to or higher than the critical temperature, the gas becomes a supercritical state, the reaction activity is remarkably increased, and the reaction efficiency is improved. The reaction using the supercritical state has attracted a great deal of attention recently due to its unique reactivity, but the conventional method leads the entire reaction element in the reaction vessel to the supercritical state at high temperature and high pressure, so many It requires energy and a high pressure resistant device, and has a large operational risk. On the other hand, the present invention maintains the temperature above the critical temperature to form microbubbles even when the gas is at a pressure much lower than normal pressure or critical pressure, and the microbubbles are destroyed or miniaturized / erased. In the process, a supercritical state is created by limiting to the reaction local area. Compared with the conventional method, the energy consumption / device cost is small and the safety is high. In addition, in the conventional method, because of the high pressure, there was a technical difficulty in obtaining a uniform mixed state of gas and liquid, but in the present invention, a gas having a pressure much lower than normal pressure or critical pressure is present. Is dispersed as microbubbles, so that the homogenization operation is easy.

Third Embodiment: As described in (4), the third embodiment uses ultrasonic waves to break bubbles to obtain useful products, and is used in the reaction vessel or on the reaction vessel wall. An ultrasonic vibration generating element is installed to radiate ultrasonic waves into a liquid containing bubbles. For bubbles in the liquid, it is said that a resonance frequency corresponding to the bubble diameter is required, unlike the case where it is used for defoaming in general brewing industries, etc., when a considerable distribution is seen in the bubble diameter For this, a variable frequency facility is desirable. Although the destructive action by ultrasonic waves is strong, it is unavoidable to increase the cost for the equipment, and it is necessary to compare with the effect of improving the reaction efficiency.

Fourth Embodiment: In the fourth embodiment, as described in (5) to (11), a stationary structure is installed in a reaction vessel, and a liquid containing bubbles is guided to the structure. The process of creating / breaking or miniaturizing / disappearing bubbles is created by passing through the structure of the above or by colliding the bubbles with the structure. As the form of the structure, one or a plurality of slit aggregates such as a lattice shape and a honeycomb shape constituted by a perforated plate, a net-like material, and a thin plate, or a ring or other shape filler is used. The form is not particularly limited as long as it meets the purpose. When multiple units are used, the pore diameter / number of holes of the same structure or the same type of porous plate or the fineness of the mesh of the mesh or the fineness of the aggregate of slits are changed as necessary. Arrangement of a plurality of materials including those in which the structure is arranged in series, or the pore diameter of the perforated plate of the dissimilar structure or the perforated plate of the dissimilar structure, or the mesh fineness of the mesh or the slit fineness of the aggregate of slits is changed. To place. When using a plurality of pore diameters, mesh finenesses or slit finenesses that are changed, microbubbles sequentially pass from the ones with the smallest pore size to the ones with the smallest pore size, or those with the smallest fineness to the ones with high definition. Arrange as follows.

Speaking of the transesterification reaction between methanol and vegetable oil, the type of structure is appropriately selected according to the type of target fats and alcohols and the operating conditions (reaction temperature, flow rate of vaporized alcohol, stirring conditions, etc.). However, the reaction efficiency can be improved by installing the perforated plate in a multistage reaction vessel most simply. The installation location and the hole diameter and the number of holes of the perforated plate are determined by the type of oils and alcohols and the operating conditions. Examples of installation of perforated plates are shown in FIGS. 1a, 1b, 2a and 2b. FIG. 1a shows a case where the porous plate 5 is held by a support beam 6 installed on the wall of the reaction vessel 1, FIG. 1b shows a case where the porous plate 5 is held by a central support shaft 7 and a support beam 6, and FIG. The gas / liquid passage route is extended in combination with the baffle plate 14, and FIG. 2 b is a diagram in which the hole diameter and the number of holes of the porous plate 5 are changed. As a method for extending the gas-liquid passage route, it is also possible to form a helical route with a perforated plate. The superheated alcohol bubbles supplied from below through the nozzle 8 or a suitable bubble refiner pass through the pores of each stage of the perforated plate to newly generate bubbles having a size controlled by the pore diameter, On the other hand, repeated miniaturization or fusion by collision with the perforated plate and interaction between bubbles, the fused bubbles pass through the pores of the next perforated plate to generate new bubbles, and as the whole rises, it becomes finer and disappears Head in the direction of In each of these examples, the bubbles react with the fats and oils 4 supplied from the upper part of the reaction vessel through the fats and oils supply nozzle 9, and the resulting reaction product 2 is collected from above as a gas phase together with excess superheated vaporized alcohol. The The supply of fats and oils does not necessarily have a relationship between the superheated vaporized alcohol and the counter flow as in each example, and can be performed as a parallel flow from below, and an appropriate method is taken depending on the operating conditions. (Hereafter, the same applies to each manufacturing method).

Usually, as a structure used in a gas-liquid reactor for promoting the reaction, for example, there is a static mixer typified by a sulzer type, but the structure using a perforated plate according to the present invention has a simpler structure than these. And maintenance is easy.

Fifth Embodiment: In the fifth embodiment, as described in (12), mechanical vibration is applied to the structure described in (5) to (11), and bubbles are generated / destroyed or miniaturized / disappeared. The effect of this is further enhanced. If the perforated plate has a structure having a center support shaft 7 as shown in FIG. 1B, for example, the center shaft can be vibrated by an appropriate device to cause vertical vibration.

Sixth Embodiment: As described in (13), the sixth embodiment imparts catalytic action to the structure described in (5) to (12), and further improves the reaction rate between gas and liquid. It is intended. The transesterification reaction between fats and oils and alcohol can be most simply carried out by making the porous plate made of lead, tin or zinc or coated with the metals.

Each of the fifth and sixth embodiments contributes to the improvement of the reaction efficiency, but it also causes an increase in cost, so that it is necessary to consider the effect of improving the reaction efficiency.

Seventh Embodiment: In the seventh embodiment, as described in (14), the structure described in (5) to (13) and a draft tube are used together. As shown in the figure, a draft tube is installed outside the perforated plate, and the liquid material rising through the structure or the liquid material accompanied by bubbles depending on the flow velocity descends outside the draft tube and is again inside the draft tube. The flow that increases the chance of contact between the bubbles and the liquid material is smoothly performed. When bubbles are accompanied by a liquid material, the rising speed of the bubbles decreases as the bubble size decreases, so the bubbles in the descending gas-liquid mixture are smaller than those in the newly rising gas-liquid mixture. Many of them can also be expected to have a large bubble destruction effect (Japanese Patent Application No. 2003-3139636) due to microbubbles. By forming the draft tube with a pore plate, it is possible to further increase the mixing efficiency of the descending gas-liquid mixture and the newly rising gas-liquid mixture. In the reaction vessel, deteriorated raw materials may accumulate over time, which may hinder the reaction efficiency, but the smooth circulation flow by the draft tube is directed downward of the deteriorated products having a higher specific gravity than the raw oils and fats. The effect of facilitating separation is also expected. FIG. 3b shows a case where a draft tube is installed at the center of the perforated plate to increase the effective area of the perforated plate. In this form, the liquid substance that has risen through the structure or the liquid substance accompanied by bubbles depending on the flow velocity descends inside the draft tube.

Eighth Embodiment: In the eighth embodiment, as described in (15), a plurality of reaction units are installed in parallel in one reaction vessel to improve production efficiency. FIG. 4a shows a schematic diagram of an example in which a reaction unit having a draft tube 10 and a perforated plate 5 is used, and FIG.

Ninth Embodiment: In the ninth embodiment, as described in (16), a jacket is installed around the reaction unit to facilitate temperature control of the reaction unit. If necessary, divide the jacket into multiple parts, creating a temperature distribution suitable for each. FIG. 5a shows an example of a jacket 11a having a gas-liquid common circulation hole 13 in the center and a reaction unit installation hole 12 around the hole, and FIG. 5b shows a schematic example of a reaction vessel in which the jacket 11a and a porous plate 5 are installed as a reaction unit. The figure is shown. In this example, the downflow in the gas-liquid circulation is performed collectively through the central common circulation hole. FIG. 6a shows an example of a jacket 11b having no common circulation hole and a reaction unit installation hole 12 in the entire cross section. FIG. 6b shows a reaction vessel in which the jacket 11b and a draft tube 10 and a porous plate 5 are installed as a reaction unit. A schematic diagram of an example is shown. In the example of FIG. 6b, gas-liquid circulation is performed independently for each reaction unit.

Tenth Embodiment: As described in (17), in the tenth embodiment, in the manufacturing method of the present invention, gas blowing is performed through a porous sintered body made of metal or ceramic having a hole diameter of 0.5 mm, for example. Is what you do. In the present invention, the reaction efficiency can be improved by simply injecting gas from a pipe having a hole diameter of about 5 mm. However, depending on the type of oil and fat and the type of the reaction unit, it is better to send fine bubbles from the beginning. Results are obtained.

Eleventh Example: In the eleventh example, as described in (18), a plurality of reaction processes are constructed by connecting a plurality of the same or different production methods in the present invention in series. FIG. 7 shows a schematic diagram of an example of a two-stage process using a reaction unit of a perforated plate 5 having a draft tube 10. Usually, the capacity of the reaction vessel in the second stage is set smaller than that in the first stage. Speaking of the transesterification reaction between fats and alcohols, in the first-stage reaction vessel on the left side, the raw fats and oils 4 are supplied from the top through the fats and oils supply nozzle 9 and blown from the bottom through the nozzle 8. The reaction product 2 (ester and glycerin) produced by reacting with the superheated vaporized alcohol 3 is collected from above as a gas phase together with excess superheated vaporized alcohol. At this time, usually only an excessive amount of superheated vaporized alcohol cannot entrain all of the reaction product into the gas phase, and in a single-step reaction process, the residual reaction product remains in the reaction vessel and accumulates. However, in the two-stage process as in this example, the residual reaction product is supplied together with unreacted oils and fats from below to the upper part of the second-stage reaction vessel on the right side. In the second stage, the reaction product produced by the superheated vaporized alcohol 3 and the unreacted oils and fats supplied from the lower part of the reaction vessel and the residual reaction product produced in the first stage are both excessive as the reaction product 2. It is collected from above as a gas phase with superheated alcohol. By this method, by appropriately setting the amount of superheated vapor to be distributed to the first and second stages, it is possible to improve the ester collecting efficiency from the superheated vapor as a whole. In addition, when the degradation product of fats and oils accumulates in the reaction vessel, the reaction efficiency may decrease. However, in this method, the degradation product does not accumulate in the first-stage reaction vessel, and the reaction efficiency is the initial value. Therefore, it is easy to suppress a decrease in apparatus efficiency by extracting the deteriorated products little by little in the second stage.

Fill a 50 mm diameter stainless steel cylindrical container with rapeseed oil (purity 92%) up to a height of 215 mm, and inject superheated methanol (purity 99.7%) at a temperature of 290 ° C. using a stainless steel tube 5 mm in diameter from the bottom. In the experiment of collecting the reaction product (fatty acid methyl ester) together with excess methanol, when 10 pore plates (46 mm in diameter, 3.6 mm in pore diameter, 37 pores) are placed in rapeseed oil in series at 15 mm intervals FIG. 8 shows the result of comparison of the ester acquisition amount (l) / methanol blowing amount (l) with the case of no porous plate. Line graphs 15 and 16 (16 is the fifth repeated experiment under the same conditions) when a porous plate is used (methanol supply rate 0.7 ml / min), 3 is a case without a porous plate (methanol supply rate 2.4 ml / min) min), and when the reaction reaches a substantially stable state 2 to 4 hours after the start of the experiment, the ester acquisition ratio without the pore plate is about 0.3, whereas the porous plate is used. In this case, the reaction efficiency is remarkably increased from 0.6 to 0.7.

The present invention makes it possible to improve the reaction efficiency without the need for a large increase in cost and without adverse effects such as side reactions, and has a wide range of practical applications in the field of gas-liquid reaction, especially biodiesel production. There is expected.

It is a schematic diagram of the example of arrangement | positioning of a perforated plate. It is a schematic diagram of the example of arrangement | positioning of a perforated plate. It is a schematic diagram of the example which used the perforated plate and the baffle plate together. It is a schematic diagram of the example of arrangement | positioning which changed the hole diameter / hole number of the perforated plate. It is a schematic diagram of the example which installed the draft tube outside the perforated panel. It is a schematic diagram of the example which installed the draft tube inside the perforated panel (central part). It is a schematic diagram of the example which arrange | positions the several reaction unit with a draft tube in one reaction container. It is a schematic diagram of the example which arrange | positions the several reaction unit which does not have a draft tube in one reaction container. It is a schematic diagram of the example of the jacket which has the common circulation path of gas-liquid in the center. It is the schematic diagram of the example which installed the jacket of FIG. 5a in reaction container. It is a schematic diagram of the example of the jacket which does not have a common circulation path of gas-liquid. It is the schematic diagram of the example which installed the jacket of FIG. 6a in reaction container. It is a schematic diagram which shows the two-step reaction process using a perforated plate. It is an experimental result which shows the effect of the pore board with respect to ester production amount (volume) / methanol blowing amount (volume).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reaction container 2 Reaction product 3 Methanol 4 Oils and fats 5 Perforated plate 6 Support beam 7 Center support shaft 8 Superheated vaporization methanol blowing nozzle 9 Oils and fats supply nozzle 10 Draft tube 11a Jacket 11b Jacket 12 Reaction unit installation hole 13 Common gas-liquid circulation (Downstream) Hole 14 Baffle plate 15 Graph showing change over time in ester production amount / methanol blowing amount when using porous plate Graph 17 showing change over time in ester production amount / methanol blowing amount when using porous plate No porous plate used Graph showing the change over time in the amount of ester produced and the amount of methanol blown

Claims (18)

In the process of obtaining a useful product by injecting gas into the liquid substance in the reaction vessel and reacting between the liquid substance and the gas, the purpose is mainly at the time of generation / destruction or miniaturization / extinction of bubbles of the gas. Or a part of the target reaction. Blowing superheated vaporized alcohol into the liquid fats and oils in the reaction vessel, transesterifying the microbubbles of alcohol and fats and oils, and the product in the gas phase with excess superheated vaporized alcohol A method for producing a fatty acid ester, characterized in that, in the method for producing a fatty acid ester to be obtained, the transesterification reaction or a part of the transesterification reaction is caused mainly when alcohol bubbles are generated / destroyed or miniaturized / disappeared. The manufacturing method according to claim 1 or 2, wherein a gas pressure in the bubble by a sum of a surface tension or a surface tension of the bubble and an external pressure is a critical pressure of the gas or a critical pressure or more, and A useful product or a method for producing a fatty acid ester among useful products, characterized in that the gas temperature in the bubbles is the critical temperature of the gas or higher than the critical temperature. 4. A useful product or a useful product according to any one of claims 1 to 3, wherein microbubbles are destroyed or micronized / erased by irradiation with ultrasonic waves of constant or variable frequency. Among them, a method for producing a fatty acid ester in particular. The production method according to any one of claims 1 to 3, wherein a structure for generating / breaking or micronizing / disappearing microbubbles is installed in the reaction vessel. Among the products, in particular, a method for producing a fatty acid ester. 6. The production method according to claim 5, wherein the structure is a perforated plate, and in particular, the production method of a fatty acid ester among useful products or useful products. 6. The manufacturing method according to claim 5, wherein the structure is a net-like material, a lattice-like, honeycomb-like or other aggregate of slits constituted by thin plates, or a ring-like filling. A useful product or a method for producing a fatty acid ester among useful products. The manufacturing method according to claim 6 or 7, wherein the structure has the same structure or the same kind of structure, and the pore diameter of the perforated plate, the mesh fineness of the mesh, or the slit fineness of the aggregate of slits is changed. A method for producing a fatty acid ester, particularly among useful products or useful products, characterized in that a plurality of such products are installed in series. 8. The manufacturing method according to claim 6 or 7, wherein the structure is of a different structure, or the pore diameter of the perforated plate or the mesh fineness of the mesh or the slit fineness of the aggregate of slits is changed in the different structure. A method for producing a fatty acid ester, particularly among useful products or useful products, characterized in that a plurality of them are installed in series. 10. The manufacturing method according to claim 8 or 9, wherein a plurality of the pores of the perforated plate of the structure, the mesh fineness of the mesh, or the slit fineness of the aggregate of slits are changed in series. In this case, it is characterized in that the liquid substance and the bubbles are set so as to pass through those having a large pore diameter in order from the one having a large pore diameter, or those having a fineness from one having a fine mesh definition or a coarse slit definition. A useful product or a method for producing a fatty acid ester among useful products. When a plurality of perforated plates are installed in series, a plurality of baffle plates are used in combination to extend the passage of liquids and bubbles, particularly among useful products or useful products, fatty acid esters Manufacturing method. 12. The production method according to claim 5, wherein mechanical vibration is imparted to the structure, and in particular, a fatty acid ester production method among useful products or useful products. The manufacturing method according to any one of claims 5 to 12, wherein the material of the structure catalyzes a reaction between the liquid substance and the gas, particularly a transesterification reaction between an alcohol and an oil. A useful product or a method for producing a fatty acid ester among useful products. 14. The production method according to claim 5, wherein a draft tube is installed in the structure, and particularly a useful product or a production method of a fatty acid ester among useful products. 15. The manufacturing method according to claim 5, wherein a structure for generating / destructing or miniaturizing / disappearing microbubbles or a mechanism such as a draft tube associated with the structure (hereinafter collectively referred to as a structure) A method for producing a fatty acid ester, particularly among useful products or useful products, characterized in that a plurality of reaction units are provided in parallel in a reaction vessel. 16. The production method according to claim 15, wherein one or more jackets are provided around the reaction unit, and a heat medium is circulated in the jacket to control the temperature in the reaction unit. Among the useful products, in particular, a method for producing a fatty acid ester. The production method according to any one of claims 5 to 16, wherein the gas is blown through a porous sintered body made of metal or ceramics. Especially the manufacturing method of fatty acid ester. The production method according to any one of claims 5 to 17 is repeatedly used, or one or more of the production methods are combined with a gas-liquid reaction apparatus other than the production method to perform a multistage reaction process. A useful product or a method for producing a fatty acid ester among useful products, characterized in that it is constructed.

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