KR20220170545A - Oil extraction and biodiesel conversion process from microalgae - Google Patents

Abstract

The present invention relates to a process for extracting oil from microalgae and a biodiesel conversion process, wherein the oil to be used as a raw material of biodiesel is extracted from microalgae with a high yield and the extracted microalgae oil is used to produce biodiesel with high efficiency. The process of the present invention comprises: a first step of extracting oil as a raw material of biodiesel from microalgae; a second step of supplying the oil extracted in the first step along with methanol to each supply tank (100); a third step of making the oil and methanol supplied through the second step react with the preset amount of an alkaline solid catalyst and a solid acid catalyst in a reactor (300); a fourth step of depositing and isolating a reaction mixture generated through the third step; and a fifth step of removing methanol from the reaction mixture deposited and isolated through the fourth step and distilling the remaining to convert the same into biodiesel.

Description

Oil extraction and biodiesel conversion process from microalgae}

The present invention relates to a process for extracting oil from microalgae and converting biodiesel to high-efficiency biodiesel using microalgal oil extracted while extracting oil as a raw material for biodiesel from microalgae with high yield.

Among various fuels obtained from crude oil, diesel oil has the advantages of excellent fuel efficiency, low price, and low carbon dioxide emissions, but on the other hand, it has the disadvantage of generating a large amount of air pollutants after combustion.

Therefore, various methods for overcoming the disadvantages of diesel oil have been proposed. In addition, biodiesel is actively researched as an alternative fuel that has properties similar to those of diesel oil, is excellent in terms of economy, and can prevent or reduce air pollution.

The above biodiesel is a natural circulating energy, and it usually undergoes a transesterification reaction between triacylglycerol, which is the main component of vegetable oils such as rapeseed oil, soybean oil, sunflower oil, and palm oil, and alcohol under an acid or alkali catalyst. (transesterification).

However, as the use of biodiesel soared worldwide, the price of vegetable oil that had been used so far skyrocketed, causing food shortages and serious destruction of land resources. Thus, the need to manufacture biodiesel using non-edible raw materials this has come to light.

Microalgae, one of the non-edible raw materials, is a unicellular organism capable of growing through photosynthesis using water, carbon dioxide, and solar energy, and is also known as phytoplankton. Microalgae, which fix carbon dioxide with higher efficiency than terrestrial plants, grow relatively faster than other terrestrial plants, and their oil productivity per unit area is soybean (446L/ha to 635L/ha) or oil palm (5,366L/ha to 5,366L/ha). 5,950 L / ha) (microalgae: 58,700 L / ha to 97,790 L / ha), it is in the spotlight as a third-generation non-edible raw material for the production of biodiesel.

However, unlike plants in which photosynthetic products are transported and stored in seeds, microalgae consist of a single cell system in which photosynthetic organs and lipid storage organs coexist, and oil extracted therefrom is difficult to use as a raw material for biodiesel. There are three major ones.

First of all, the first problem is that, unlike plant seeds, which are mostly neutral lipids, microalgae contain a large amount of carbohydrates, proteins, polar lipids (PLs) and pigments in addition to neutral lipids (NLs). to be.

Therefore, when oil is extracted from microalgae, a small amount of impurities such as carbohydrates, proteins, polar lipids, and pigments are extracted together in addition to neutral lipids, which are raw materials for biodiesel, and these are factors that lower the yield in the biodiesel conversion process. It works.

The second problem is that microalgae oil (neutral lipid) extracted with a non-polar solvent such as nucleic acid contains a large amount of free fatty acids in addition to triacylglycerol, which is the main raw material for conventional biodiesel production.

Most of the existing biodiesel production processes are transesterification of alcohols such as triacylglycerol and methanol, and acid or base catalysts are used to speed up the exchange reaction. In general, the reaction time of 30 hours or more in the case of an acid catalyst and 2 hours or more in the case of a base catalyst is required, so conversion by a base catalyst is preferred. (acid value 1 or more), while the saponification reaction is performed, the conversion rate due to the loss of the catalyst decreases.

In addition, since the biodiesel conversion process using an acid or base catalyst necessarily requires a washing process using hot water, there are problems such as generation of a large amount of wastewater and maintenance loss.

Therefore, since there are limitations in applying the existing process to biodiesel conversion of raw materials containing a large amount of free fatty acids, such as microalgal oil, research on new conversion methods is being conducted. For example, European Patent Publication No. 3026096 proposes a two-step process in which free fatty acids in oil are first esterified and then the oil is transesterified at a temperature of about 65° C. under a sulfuric acid or sulfonic acid catalyst. An esterification reaction is performed by reacting a mixture of fatty acids and fatty acid triacylglycerols with methanol.

In addition, US Patent Publication No. 2011/0144375 discloses a method for increasing the yield of fatty acid alkyl esters by simultaneously performing esterification and transesterification by reacting a mixture of free fatty acids, fats and oils with alcohol in the presence of ceramics. It is presented.

However, in the above method, there is a problem in that the reaction conversion rate is low because the input amount of the catalyst is excessive and the water produced in the esterification reaction and the glycerin produced in the transesterification reaction are not effectively discharged to the outside of the reaction system.

On the other hand, a final problem associated with the conversion of microalgal oil to biodiesel is that microalgal oil contains higher amounts of polyunsaturated fatty acids than vegetable oils.

An appropriate amount of unsaturated fatty acids lowers the viscosity of biodiesel to make it flowable and improves the cold filter plugging point of diesel, but an excessive amount of unsaturated fatty acids lowers the oxidative stability of biodiesel. do.

Therefore, in the existing biodiesel process, an oxidation stabilizer or the like is added to solve the problem in order to increase oxidation stability of fatty acid alkyl esters prepared from raw materials having a high content of unsaturated fatty acids such as soybean oil.

However, unlike soybean oil, microalgal oil contains a large amount of polyunsaturated fatty acids, including omega-3, which can be used as high value-added substances. It acts as a factor that lowers the economy.

That is, when the existing process is applied to microalgae oil containing a large amount of polyunsaturated fatty acids, problems such as deterioration in oxidative stability may occur in the biodiesel produced along with a decrease in economic feasibility.

European Patent Registration No. 3026096 (Method for preparing fatty acid alkyl ester using fat, registered on February 27, 2019) US Patent Publication No. 2011/0144375 (Process for production of biodiesel, published on June 16, 2011) Korean Patent Registration No. 10-1265759 (Method and device for producing fatty acid alkyl esters using fatty acids, published on May 20, 2013)

The present invention was conceived to solve all the problems of the prior art as described above, and an object of the present invention is to extract oil, which is a raw material for biodiesel, from microalgae in high yield, while using a solid catalyst with excellent reaction stability. It is possible to prevent the loss of activity of the solid catalyst during the reaction process, and to promote the reaction by reacting the solid catalyst with excellent catalytic activity with microalgae extract oil and methanol, thereby improving the productivity of biodiesel. It is to provide an oil extraction and biodiesel conversion process.

In addition, the present invention may have as its object to achieve other objects that can be easily derived by a person skilled in the art from the general description of the present specification in addition to the above clear objects.

The technical problem-solving means of the present invention for achieving the above problem is a first step of extracting oil, which is a raw material for biodiesel production, from microalgae, and each supply tank (100) with the oil extracted in the first step together with methanol ), and a third process in which the oil and methanol supplied through the second process are reacted with a set amount of alkali solid catalyst or acid solid catalyst in the reactor 300 process, a fourth process of precipitating and separating the reaction mixture generated through the third process, and a fifth process of removing methanol from the reaction mixture precipitated and separated through the fourth process and distilling it to convert it into biodiesel. It is done.

The first process according to an embodiment of the present invention, a) mixing microalgae and water in a weight ratio of 1:3.5-4.5; b) adding 250 to 350 parts by weight of water to 100 parts by weight of the water-mixed microalgae of step a) and then dispersing it; c) forming a microalgae mixture by adding 200 to 300 parts by weight of a solvent to 100 parts by weight of the dispersed microalgae of step b) and then mixing them; d) crushing the microalgae mixture of step c) with a cavitation crusher; e) centrifuging the crushed microalgae mixture of step d) to obtain only the filtrate from which solids are removed; and f) removing the solvent from the filtrate of step e).

Meanwhile, the reactor 300 according to the first embodiment of the present invention includes an inner tank 320 having a space therein; an outer tank 340 disposed outside the inner tank 320; A closed channel 360 formed between the inner tank 320 and the outer tank 340; and at one side of the bottom of the outer tank 340, an inlet 342 communicating with the closed channel 360 is provided. and a water outlet 344 communicating with the closed channel 360 is formed on one upper side of the outer tank 340 .

The reactor 300 according to the second embodiment of the present invention includes an inner tank 320' having a space therein; an outer tank 340' disposed outside the inner tank 320'; It consists of a closed channel 360' formed between the inner tank 320' and the outer tank 340', and is constant from one side of the bottom part of the outer tank 340' to one side of the upper part through one side of the outer tank 340'. A plurality of inlets 342' communicating with the closed channel 360' are formed at intervals, and the closed channel ( 360') and a plurality of outlets 344' communicating with each other, and the plurality of inlets 342' are provided with valves 380 for regulating fluid flow.

According to an embodiment of the present invention, when the oil and methanol react with an alkali solid catalyst, they are separated into biodiesel and glycerin by transesterification, and acid solid catalyst and During the reaction, it is separated into biodiesel and water due to the action of esterification, and the solid catalyst is characterized in that it is formulated into one or more shapes selected from cylindrical, spherical, and polygonal shapes.

According to the oil extraction and biodiesel conversion process from microalgae of the present invention, oil to be used as a biodiesel raw material is extracted from microalgae in high yield, while the activity of the solid catalyst is lost in the reaction process through a solid catalyst with excellent reaction stability. This phenomenon can be prevented, and the productivity of biodiesel can be improved by accelerating the reaction by reacting a solid catalyst with excellent catalytic activity with microalgae extraction oil and methanol.

1 is a schematic diagram showing a biodiesel conversion process in an embodiment of the present invention;
Figure 2 is a schematic diagram showing the process of extracting oil from microalgae in an embodiment of the present invention;
3 is a side cross-sectional view showing the structure of a reactor according to a first embodiment of the present invention;
Figure 4 is a side cross-sectional view showing the structure of a reactor according to a second embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. For reference, in describing the present invention below, terms referring to the components of the present invention are named in consideration of the functions of each component, so they should not be understood as limiting the technical components of the present invention. will be. In addition, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description will be omitted.

Figure 1 is a schematic diagram showing a biodiesel conversion process in an embodiment of the present invention, Figure 2 is a schematic diagram showing a process of extracting oil from microalgae in an embodiment of the present invention, Figure 3 is a schematic diagram according to the first embodiment of the present invention Side cross-sectional view showing the structure of a reactor, Figure 4 is a side cross-sectional view showing the structure of a reactor according to a second embodiment of the present invention.

As shown in FIG. 1, the process of extracting oil from microalgae and converting biodiesel according to the present invention includes a first process of extracting oil, which is a raw material for biodiesel, from microalgae, and converting the oil extracted in the first process to methanol A second step of supplying the oil and methanol supplied through the second step to each supply tank 100 together with a set amount of alkali solid catalyst or acid in the reactor 300 A third process of reacting with a solid catalyst, a fourth process of precipitating and separating the reaction mixture generated through the third process, and biodiesel by removing methanol from the reaction mixture precipitated and separated through the fourth process and distilling it It consists of a fifth step of converting to

According to an embodiment of the present invention, the first step, a) mixing the microalgae and water at a weight ratio of 1:3.5-4.5; b) adding 250 to 350 parts by weight of water to 100 parts by weight of the water-mixed microalgae of step a) and then dispersing it; c) forming a microalgae mixture by adding 200 to 300 parts by weight of a solvent to 100 parts by weight of the dispersed microalgae of step b) and then mixing them; d) crushing the microalgae mixture of step c) with a cavitation crusher; e) centrifuging the crushed microalgae mixture of step d) to obtain only the filtrate from which solids are removed; and f) removing the solvent from the filtrate of step e).

Referring to an embodiment of the first process with reference to FIG. 2, first, in step a), when the amount of microalgae added per hour is set to 120 kg/hr and the amount of water added per hour is set to 480 kg/hr, the step b) In step a), 360 kg/hr of water is added to 600 kg/hr, which is the total mixing amount of microalgae and water, and then dispersed to form a microalgae dispersion.

Next, in step c), 240 kg/hr of solvent was added to the dispersed microalgae in step b), and then mixed to form a microalgae mixture, and in the crushing step, which is step d), the microalgae were crushed using a cavitation crusher. The algae mixture is circulated 3 to 5 times under the condition of 3000 kg/hr.

In step e), the microalgae mixture crushed by the cavitation crusher in step d) is centrifuged. For example, when the pulverized microalgae mixture is centrifuged, the lysate in the solid state is approximately 577.2 kg / hr, and the water and solvent mixture in the liquid state is approximately 360 kg / hr and 262.8 kg / hr.

In step f), the solvent is removed from the filtrate of step e). For example, when the solvent is removed under the condition of 240 kg/hr in step f), the throughput per hour according to oil yield is approximately 21.6 kg/hr.

The second process of the present invention performs a process of supplying the oil extracted from microalgae in the first process to each supply tank 100 together with methanol. As shown in FIG. 1, the supply tank 100 is provided with an oil supply tank and a methanol supply tank separately so as to supply oil and methanol, respectively.

According to the present invention, the raw materials supplied to the supply tank 100 may be subjected to an agitation process through an agitator, and a static mixer (not shown) may be provided to increase agitation efficiency.

As an embodiment of the static mixer, a passage is provided inside, an inlet and an outlet are formed on one side and the other side, respectively, and a spiral stirring unit for stirring the injected fluid is provided in the passage. .

The reactor 300 according to the present invention is a cylindrical tank in which oil extracted from microalgae, methanol, and a solid catalyst react by chemical action, and a raw material inlet for the oil and a methanol inlet for the methanol etc. are formed.

On the other hand, according to the first embodiment of the present invention, the reactor 300 can be configured in a batch control method as shown in FIG.

When the reactor 300 is configured in a batch control method, the reactor 300 includes an inner tank 320 having a space therein; an outer tank 340 disposed outside the inner tank 320; A closed channel 360 formed between the inner tank 320 and the outer tank 340;

In addition, an inlet 342 communicating with the closed channel 360 is formed on one side of the bottom of the outer tank 340, and an outlet port communicating with the closed channel 360 is formed on one side of the upper portion of the outer tank 340 ( 344) is formed.

According to the second embodiment of the present invention, the reactor 300, as shown in FIG. 4, can be configured in an individual control method.

When the reactor 300 is configured in an individual control method, the reactor 300 includes an inner tank 320' having a space therein; an outer tank 340' disposed outside the inner tank 320'; It may be composed of a closed channel 360' formed between the inner tank 320' and the outer tank 340'.

At this time, a plurality of inlets 342' communicating with the closed channel 360' are formed at regular intervals from one side of the bottom of the outer tank 340' to one side of the upper side through one side of the outer tank, and the outer tank ( A plurality of outlets 344' communicating with the closed channel 360' are formed at regular intervals from the other upper side of the 340' to the other lower side through the other side of the side, and the plurality of inlets 342' are fluid A valve 380 for regulating the entry and exit of may be provided.

As a modified embodiment (not shown) of the reactor 300, a driving motor providing rotational power, a rotary blade connected to a rotational shaft of the driving motor and extending to the center of the reactor 300, the driving motor It may include an inverter for adjusting the rotation shaft speed of the drive motor, a forward and reverse controller for controlling the rotation shaft direction of the drive motor to be in a forward or reverse direction, and the like.

In this case, the drive motor is preferably installed in the upper center of the reactor 300, and a plurality of rotary blades may be radially provided on the rotation axis of the drive motor extending into the reactor 300.

At this time, the rotational speed of the driving motor is preferably 80 RPM to 100 RPM per minute. This is because the reaction efficiency between each material is maximized within the above-mentioned range of revolutions per minute.

In addition, a solid catalyst shaped into a cylindrical shape, a spherical shape, a polygonal shape, and the like is provided at an end side of the rotary blade. Therefore, when the rotor blades are rotated by the driving force of the driving motor, they come into contact with the mixed reaction mixture of oil and methanol and can cause a catalytic reaction.

The inverter is provided as a means for adjusting the rotational speed of the drive motor, and the forward and reverse controller is provided as a means for controlling the rotation direction of the drive motor, that is, to control the rotation direction in a forward or reverse direction.

As another modified embodiment (not shown) of the reactor 300, a plurality of drive motors provided at regular intervals in the longitudinal direction of the side of the reactor 300 to provide individual rotational power, each rotation axis of the drive motor Rotating blades connected to and extending through one side of the side of the reactor 300 to the other side, an inverter that individually adjusts the speed of the rotation axis of the drive motor, so that the direction of the rotation axis of the drive motor is forward or reverse It may be made including a forward and reverse controller for individual control.

Meanwhile, inside the reactor 300, oil and methanol are reacted with a set amount of an alkali solid catalyst or an acid solid catalyst. At this time, when the oil and methanol react with an alkali solid catalyst, they are separated into biodiesel and glycerin by transesterification.

In addition, when the oil and methanol react with an acidic solid catalyst, biodiesel and water are separated by esterification.

Here, the solid catalyst according to the present invention is not particularly limited, and any commercially available catalyst can be applied to the present invention. However, in terms of its shape, it is preferable to have a cylindrical, spherical, polygonal or similar shape with particles larger than powder. This is to ensure that the solid state is maintained for a long time even during the production of fatty acid methyl or ethyl ester through the enhancement of the strength of the solid catalyst.

According to another embodiment of the present invention, the stirred material formed by stirring the oil extracted from microalgae and methanol in the second step may be configured to pass through the preheater.

The preheater raises the temperature in advance before oil and methanol react with the solid catalyst in the reactor 300 so that the reaction in the reactor 300 is more actively performed.

In addition, the present invention, in addition to the above-mentioned components, a methanol recovery tank for recovering methanol by injecting a mixture from which glycerin is separated in a separation tank, a washing tank for washing after recovering methanol, and a drying tank for removing water after washing to remove impurities , a biodiesel storage tank for storing biodiesel from which water has been removed in the drying tank, and the like.

Summarizing the foregoing, the present invention extracts oil, which is a biodiesel raw material, from microalgae in high yield, while using a solid catalyst with excellent reaction stability to prevent the loss of activity of the solid catalyst in the reaction process. In addition, the productivity of biodiesel can be further improved by promoting the reaction by reacting a solid catalyst with excellent catalytic activity with microalgae extraction oil and methanol. In addition, by shaping the solid catalyst into a cylindrical, spherical, or polygonal shape, the reaction can be promoted over a long period of time by maintaining the activity of the solid catalyst and preventing leaching.

As described above, the embodiment of the oil extraction and biodiesel conversion process from microalgae according to the present invention has been described, but this is an exemplary embodiment of the present invention and is not intended to limit the present invention. In addition, it is obvious to those skilled in the art that various modifications and imitations are possible within a range that does not deviate from the technical spirit of the present invention.

T: temperature sensor 100: supply tank
300: reactor 320,320': inner tank
340,340': outer tank 342,342': inlet
344,344': outlet 360,360': closed channel
380: valve

Claims (6)

A first step of extracting oil, a raw material for biodiesel, from microalgae;
A second step of supplying the oil extracted in the first step to each supply tank 100 together with methanol;
A third step of reacting the oil and methanol supplied through the second step with a set amount of alkali solid catalyst or acid solid catalyst in the reactor 300;
A fourth step of precipitating and separating the reaction mixture generated through the third step;
Oil extraction and biodiesel conversion process from microalgae, characterized by a configuration consisting of a fifth process of removing methanol from the reaction mixture precipitated and separated through the fourth process and distilling it to convert it to biodiesel. According to claim 1,
In the first step,
a) mixing microalgae and water at a weight ratio of 1:3.5-4.5;
b) adding 250 to 350 parts by weight of water to 100 parts by weight of the water-mixed microalgae of step a) and then dispersing it;
c) forming a microalgae mixture by adding 200 to 300 parts by weight of a solvent to 100 parts by weight of the dispersed microalgae of step b) and then mixing them;
d) crushing the microalgae mixture of step c) with a cavitation crusher;
e) centrifuging the crushed microalgae mixture of step d) to obtain only the filtrate from which solids are removed; and
f) removing the solvent from the filtrate of step e); oil extraction and biodiesel conversion process from microalgae, characterized in that it comprises. According to claim 1,
The reactor 300,
An inner tank 320 having a space therein;
an outer tank 340 disposed outside the inner tank 320;
A closed channel 360 formed between the inner tank 320 and the outer tank 340;
An inlet 342 communicating with the closed channel 360 is formed on one side of the bottom of the outer tank 340, and an outlet 344 communicating with the closed channel 360 is formed on one side of the upper portion of the outer tank 340. Oil extraction and biodiesel conversion process from microalgae, characterized in that the formation. According to claim 1,
The reactor 300,
an inner tank 320' having a space therein;
an outer tank 340' disposed outside the inner tank 320';
A closed channel 360' formed between the inner tank 320' and the outer tank 340'; and
A plurality of inlets 342' communicating with the closed channel 360' are formed at regular intervals from one side of the bottom of the outer tank 340' to one side of the upper side through one side of the outer tank 340', and the outer tank 340' A plurality of water outlets 344' communicating with the closed channel 360' are formed at regular intervals from the other upper side to the other lower side through the other side of the ),
Oil extraction and biodiesel conversion process from microalgae, characterized in that the plurality of inlet 342 'is provided with a valve 380 for regulating the entry and exit of the fluid. According to claim 1,
When the oil and methanol react with an alkaline solid catalyst, they are separated into biodiesel and glycerin by transesterification, and when reacted with an acidic solid catalyst, esterification ) Oil extraction and biodiesel conversion process from microalgae, characterized in that biodiesel and water are separated by the action of. According to claim 1,
Oil extraction and biodiesel conversion process from microalgae, characterized in that the solid catalyst is standardized in any one or more shapes selected from cylindrical, spherical, and polygonal.

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