JPS62198385A - Process and equipment for feeding carbon dioxide into microalgae suspension - Google Patents

Abstract

PURPOSE:The suspension of microalgae in the cultivation tank is taken out into a tightly closed vessel and carbon dioxide is added thereto and the mixture is recycled to the cultivation tank where the concentration of carbon dioxide and the gas-liquid contact area are adjusted to effect efficient feed of carbon dioxide. CONSTITUTION:A suspension of microalgae is sent into a tightly closed vessel 1 filled with a carbon dioxide-containing gas, and the suspension is brought into contact with carbon dioxide-containing gas in the vessel 1, then sent back into the cultivation tank 8 in which the microalgae is cultured under light irradiation. When the concentration of carbon dioxide lowers down to a prescribed value in the vessel 1, the gas is exchanged to adjust the concentration, and the liquid-gas contact area is controlled according to the carbon dioxide concentration. As a result, carbon dioxide is efficiently fed for the cultivation of microalgae.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention involves continuously taking out a suspension of microalgae in a culture tank where microalgae are being cultured by light irradiation, adding carbon dioxide gas thereto, and returning the microalgae suspension to the culture tank. The present invention relates to a method and apparatus for supplying carbon dioxide gas to a microalgae suspension that is returned to a microalgae suspension.

Conventionally, microalgae cultivation has been carried out for the purpose of food production, such as chlorella culture, or for the purpose of algae production and wastewater purification, such as the high-rate oxidation method used in wastewater treatment.

The supply of carbon dioxide gas to these cultures is carried out as follows. (a) Continuously aerate carbon dioxide-enriched air from the bottom of the culture tank. (b) A gas absorption tower is installed separately from the culture tank, and the microalgae suspension is introduced by spraying from above, and carbon dioxide gas-enriched air is continuously aerated from below and discharged from above. (1) Cover the culture tank with a transparent cover, and continuously aerate carbon dioxide-enriched air into the gas phase from one end and exhaust it from the other end. These methods result in releasing into the atmosphere some of the aerated carbon dioxide gas that never comes into contact with the liquid, resulting in very large losses. For this reason, at present, cultivation of microalgae using aerated carbon dioxide gas as a carbon source is hardly carried out.

However, if the above-mentioned losses are improved, the production price of algae can be significantly reduced, since carbon dioxide gas is very cheap compared to other carbon sources such as acetic acid. The present invention was made in view of these points, and an object of the present invention is to provide a method and apparatus for efficiently supplying carbon dioxide gas to the culture of microalgae.

That is, the uninvented invention first supplies carbon dioxide gas to the microalgae suspension by (a) at least part of the microalgae suspension in a tank in which microalgae are cultured under light irradiation conditions; of,
The carbon dioxide gas is dissolved in the microalgae suspension by sending it into a closed container filled with a gas containing carbon dioxide gas, and dissolving the carbon dioxide gas in the microalgae suspension by bringing the microalgae suspension into contact with the gas containing carbonic acid gas. (b) When the carbon dioxide concentration in the sealed container reaches a predetermined value, the Open the communication port that connects the top and the outside of the sealed container,
By introducing the microalgae suspension into the sealed container, the low concentration carbon dioxide-containing gas is forced out of the sealed container, and then the communication port is closed and the sealed container is sealed while discharging the microalgae suspension to the outside of the sealed container. This is carried out by repeating the second operation of introducing a new carbon dioxide-containing gas into the container and thereby filling the airtight container with the newly adjusted carbon dioxide-containing gas. This is a method of supplying carbon dioxide gas to a microalgae suspension, which is characterized by adjusting the amount of dissolved carbon dioxide gas by adjusting the gas-liquid contact area.The second method is to supply carbon dioxide gas to a microalgae suspension. In the apparatus for supplying, (c) an airtight container capable of holding a carbon dioxide gas-containing gas above and a microalgae suspension below, (d> a channel for introducing the microalgae suspension into the airtight container, ( e) A channel for taking out the microalgae suspension from the bottom of the sealed container to the outside of the sealed container, (f) A communication port that communicates the upper part of the inside of the sealed container with the outside of the sealed container, (cJ) Introducing a gas containing carbon dioxide into the sealed container. means for (i) sequentially introducing the flow path for introducing the microalgae suspension into the closed container, the inside of the closed container, and the above-mentioned flow path for taking out the microalgae suspension from the bottom of the closed container to the outside of the closed container; forced flow means for forming a flow of the microalgae suspension passing through; (i) means for opening and closing the communication port; The communication port is opened and the microalgae suspension is introduced into the sealed container to push out the low carbon dioxide-containing gas out of the sealed container, and then the communication port is closed and the microalgae suspension is introduced into the sealed container. (k) means for controlling the means for introducing new carbon dioxide-containing gas to operate for a certain period of time; This is an apparatus for supplying carbon dioxide gas to a microalgae suspension, characterized by comprising means for adjusting the amount of dissolved gas.

As described above, the present invention provides a method for transporting a microalgae suspension into a closed container filled with a gas containing carbon dioxide, and bringing the microalgae suspension into contact with the gas containing carbon dioxide in the closed container. After dissolving carbon dioxide gas in the microalgae suspension,
The gas is returned to the tank where microalgae are cultured under light irradiation conditions, and when the carbon dioxide concentration in the carbon dioxide-containing gas in the sealed container has decreased to a predetermined value, the filled gas is replaced by gas exchange. Constructed to adjust the amount of dissolved carbon dioxide by adjusting the carbon dioxide concentration and adjusting the gas-liquid contact area in the sealed container according to changes in the carbon dioxide concentration in the filled carbon dioxide-containing gas. It is characterized by the following points.

Since the present invention is configured as described above, almost all of the carbon dioxide gas introduced can be dissolved in the microalgae suspension, and the amount of dissolved carbon dioxide gas can also be adjusted.

Examples of the carbon dioxide-containing gas used in the present invention include boiler exhaust gas, fermentation plan 1 to exhaust gas, and liquefied carbon dioxide obtained by pressurizing and concentrating these.

Next, the method and apparatus of the present invention will be explained in more detail with reference to the drawings.

FIG. 1 is a longitudinal sectional view showing one embodiment of the apparatus of the present invention. In this example, the device is installed so that its upper end is below the water surface of the microalgae culture tank. The device includes a closed container 1 capable of coexisting with a carbon dioxide-containing gas above and a microalgae suspension below, and a microalgae suspension in a microalgae culture tank 8 into the closed container 1. A pipe 2 serves as a flow path for introducing the jet M, and a pipe 2 serves as a flow path for introducing the jet M from above.
It consists of a pipe 2a as a flow path, a pipe 2b as a flow path for downward introduction, and a pipe 3 as a flow path for taking out the microalgae suspension in the liquid phase to the microalgae culture tank 8. A communication pipe 4 equipped with a control valve 10 for controlling opening and closing is provided above the closed container 1. A compressor 6 is provided outside the hermetic container 1 for pressurizing a carbon dioxide-containing gas from a carbon dioxide-containing gas source 5 into the hermetic container 1 via a pipe 7. A pump 9 is provided in the tube 2 for forcibly introducing the microalgae suspension into the closed container 1 from the microalgae culture tank 8 through the tube 2, tube 2a, and tube 2b. A carbon dioxide gas analyzer 11 is provided that continuously extracts and analyzes the carbon dioxide concentration in the gas phase G, and the analyzer 11 is connected to a control valve 10 via a recording controller 12. A contact point 13 that defines the upper limit of the liquid level S is provided in the upper part of the closed container 1 and is connected to the control valve 10 via a controller 18 . Also, the contact 13 is connected to the controller 18
It is also connected to the compressor 6 through it. A contact point 14 that defines a lower limit -2 of the liquid level S is provided in the lower part of the closed container 1 and is connected to the compressor 6 via a controller 18 . Contact 2
3 and 24 are provided at the same height within the closed container 1 as the contacts 13 and 14, respectively, and are connected to the pump 9 via a controller 25. Transfer the microalgae 'MI suspension to tube 2a and tube 2b.
A control valve 19 and a control valve 20 for controlling the respective flow rate ratios are provided in the pipe 2a and the pipe 2b, respectively, and the pipe 2a is branched and introduced into the closed container 1. Connect to. An atomizer 1122 for spraying liquid is provided at the tip of the branched pipe 2a, and a sequence valve 21 is provided in the branched pipe to open and close sequentially according to changes in the flow rate within the pipe 2a. A dissolved carbon dioxide measuring device 15 is disposed in a liquid phase chamber in the lower part of the sealed container 1, and is connected to a flow rate control valve 19 and a flow rate control valve 20 via a carbon dioxide gas analyzer 16 and a recording controller 17. A floating plate 31 having an opening is provided above the liquid level S in the closed container 1. floating board 3
1 has a protrusion 32 that restricts its vertical movement range.

The operating circuit of the control valve 10, consisting of the carbon dioxide analyzer 11, the recording controller 12 and the control valve 10, is of a type known per se in other fields of control technology. The operating circuit for the control valve 10 opens the control valve 10 when the carbon dioxide concentration of the gas phase G inside the closed container 1 drops to a setting predetermined by the recording controller 12. In addition, the contact 13 and the controller 18
The operating circuit of the control valve 10, consisting of the control valve 10 and the control valve 10, is of a type known per se in other control technology fields.

The operating circuit for the control valve 10 closes the control valve 10 when the liquid level S reaches the upper limit 1l11. Furthermore, the carbon dioxide-containing gas injection circuit consisting of contacts 13, contacts 14, controller 18, compressor 6, carbon dioxide-containing gas source 5 and tube 7 is of a type known per se in other control technology fields. This carbon dioxide-containing gas injection circuit operates the compressor 6 when the liquid level S reaches the upper limit, and
When this temperature is reached, the process is stopped, and a certain amount of carbon dioxide-containing gas is pressurized into the sealed container 1 to adjust the carbon dioxide concentration. Contact 2
The microalgae suspension introduction circuit consisting of 3, contacts 24, controller 25 and pump 9 is also of a type known per se in other control technology fields. This fine class 91 suspension introduction circuit stops the pump 9 when the liquid level S reaches the upper limit, and starts operating it when the lower limit is reached. Stop introducing the cloudy liquid. The flow control circuit consisting of the carbon dioxide meter 15, the carbon dioxide analyzer 16, the recording control 31γ, the flow control valve 19 and the flow control valve 20 is also of a type known per se in other control technology fields. This flow rate control circuit controls the flow rate of the microalgae suspension that is sprayed from above into the sealed container 1 through the pipe 2a and to which carbon dioxide gas is added, and the flow rate of the microalgae W! introduced into the sealed container 1 from below through the pipe 2b. ! A microalgae suspension with a substantially constant carbon dioxide concentration is generated in the liquid phase by adjusting the flow rate ratio of the suspension. The microalgae suspension introduced through the tube 2b is a microalgae suspension to which carbon dioxide gas is added, which mainly moves downward through the openings of the floating plate 31, with the addition of carbon dioxide gas being restricted by the floating plate 31. Serves as a diluent.

Carbon dioxide analyzer 11, recording controller 12 and till control
In the operation circuit of the control valve 10 including the valve 10, a carbon dioxide gas analyzer 11 continuously analyzes the carbon dioxide concentration in the gas phase G. The carbon dioxide gas analyzer 11 is, for example, an infrared carbon dioxide gas analyzer, which is characterized by extremely fast response speed and can be connected to the recording controller 12. An infrared carbon dioxide gas analyzer consists of an analysis sample chamber through which sample gas is continuously passed, and an analysis comparison chamber filled with nitrogen gas, and infrared rays are emitted equally into both chambers. The infrared rays passing through the sample 13+ chamber are absorbed by the carbon dioxide gas in the sample, and its transmission strength is reduced according to the concentration of carbon dioxide gas. On the other hand, since there is no carbon dioxide gas in the comparison chamber, the infrared rays passing through this chamber do not decrease. The infrared carbon dioxide gas analyzer detects the energy difference of the infrared rays passing through each chamber as a current, and amplifies this to a standard signal range appropriate for the standard controller. Recording controller 1
Reference numeral 2 comprises the above-mentioned controller combined with a recorder, and the recording controller 12 continuously indicates and records the carbon dioxide concentration.

The controller in the recording controller 12 compares the input signal with a predetermined set value, and sends a signal to the C-control well 10 to open if the carbon dioxide level S is below the set value.

When the control valve 10 is opened, the gas in the closed container 1 is released to the outside in order to introduce new carbon dioxide-containing gas. The set value is determined primarily from an economic standpoint, and it is desirable to keep it as low as possible, but the temperature of carbon dioxide in the atmosphere is approximately 0.0.
3% or more is required.

Carbon dioxide measuring device 15, carbon dioxide gas analyzer 161. In the flow rate control circuit consisting of the recording control device 17, the flow rate control valve 19, and the flow rate control valve 20, the carbon dioxide measuring device 15 senses the concentration of dissolved carbon dioxide in the lower part of the liquid phase. Carbon dioxide measuring device 15
For example, the electrode is a carbon dioxide gas electrode, which consists of a reference electrode and a glass electrode immersed in an electrolytic solution, and is separated from the liquid in the liquid phase chamber by a Teflon membrane.

The dissolved carbon dioxide concentration is proportional to the current generated between the two electrodes.

Dissolved carbon dioxide I! Carbon dioxide measurement device 15 as a measure of degree
The current output from the is analyzed by a carbon dioxide analyzer and amplified to the appropriate standard signal range for the standard controller. The recording controller 17 consists of the above-mentioned controller combined with a recorder, and the recording controller 11 continuously indicates and records the dissolved carbon dioxide concentration. A controller in recording controller 17 compares the input signal with a predetermined setting value and sends a signal to flow control valve 19 and flow control valve 20. Dissolved carbon dioxide concentration is 52
If it is lower than the fixed value, the flow rate control valve 19 and the flow rate control valve 20
are sent signals for opening and opening, respectively, and vice versa. The set value is determined by the amount of carbon dioxide required by the microalgae in the microalgae culture tank 8 and the discharge amount of the pump 9.

According to the device, the method of the invention proceeds as follows.

It is assumed that before the start of operation, the liquid level S in the closed container 1 is at the upper limit. Upon start of operation, a signal from the contact 13 is sent to the controller 18, which closes the control valve 10 and activates the compressor 6 to transfer the carbon dioxide-containing gas from the carbon dioxide-containing gas source 5 through the tube 7 to a closed container. Press fit into 1. Liquid level S
When the lower limit is reached, a signal from contacts 14 is sent to the controller 18, which stops the compressor 6, and a signal from contacts 24 is sent to the controller 25, which activates the pump 9. The flow rate of pump 9 can be changed as necessary. By operating the pump 9, the microalgae suspension is introduced into the closed container 1 through the tube 2, and the tubes 2a and 2b branched from the tube 2, and after carbon dioxide is added to the liquid, the microalgae suspension is introduced through the tube 3. The microalgae is taken out by overflowing into the microalgae culture tank 8. This addition of carbon dioxide gas is performed while the microalgae suspension introduced through the pipe 2a falls from the gas phase G as fine droplets,
The liquid is diluted by the microalgae suspension introduced via tube 2b. The carbon dioxide measuring device 15 detects dissolved carbon dioxide in the microalgae suspension and sends a signal to the analyzer 16. Analyzer 16 then sends a signal to recording controller 17 which adjusts flow control valve 19 and flow control valve 20. If the dissolved carbon dioxide concentration is lower than the set value, the flow rate control valve 19 opens further;
The flow control valve 20 is further closed. As a result, the sequence valve 21 is sequentially opened according to the flow rate, and the spray amount increases.
The gas-liquid contact area increases, and the amount of carbon dioxide gas added increases. Conversely, if the dissolved carbon dioxide concentration is higher than the set value, the flow rate control valve 19 is further closed and the flow rate control valve 20 is further opened. As a result, the sequence valve 21 is sequentially closed according to the flow rate, the amount of spray is reduced, the gas-liquid contact area is reduced, and the amount of carbon dioxide gas added is reduced. The setting value of the recording v controller 17 can be changed according to the required amount. Normally, the carbon dioxide concentration in the gas phase G gradually decreases, so the flow rate control valve 19 is gradually opened and the flow rate control valve 20 is gradually closed.

In this way, when the carbon dioxide concentration in the gas phase G falls to the set value set in advance in the sacred treasure 12, the control valve 10 is opened and the liquid level S rises.

The liquid level S reaches the upper limit 41 and returns to the state before the start of operation. Again the signal from contact 13 is sent to controller 18 which activates compressor 6 and at the same time the signal from contact 23 is sent to controller 25 which stops pump 9.

The compressor 6 pressurizes the carbon dioxide gas while moving the liquid level S downward.

When the liquid level S reaches the lower dry limit, a signal from contacts 14 is sent to the controller 18, which stops the compressor 6, and a signal from contacts 24 is sent to the controller 25, which starts the pump 9 and starts carbonation. Addition of gas takes place. Thereafter, the above operations are repeated until the end of the operation.

The setting value for the recording controller 17 is microalgae! Determined based on J turbidity flow rate and the required amount of carbon dioxide in the microalgae culture tank 8. This method for determining the required amount of carbon dioxide is well known in the art of algae cultivation. The required amount of carbon dioxide is the light heat of the culture tank! )1i1fii product, light heat tA,
It depends on the algae concentration, water temperature, carbon dioxide fixed specific rate of algae, etc. Therefore, in an offline experiment, we determined the amount of carbon dioxide fixed per amount of light absorbed at each water temperature, the relationship between algae concentration, water depth, and light absorption rate, and in actual outdoor cultivation, we also used the results of the offline experiment. Calculate the light absorption rate from the algae concentration and water depth, and then calculate the required amount of carbon dioxide by multiplying it by the fixed amount of carbon dioxide per amount of light absorbed, the light irradiation area of the culture tank, and the amount of sunlight irradiation. decide. In normal outdoor cultivation, cultivation is carried out at a concentration of algae that absorbs all the light that can be absorbed by photosynthetic pigments for the purpose of effective use of light, so the absorption rate is approximately It may be set to 45%.

The amount of carbon dioxide gas required per unit time determined in this way is divided by the amount of flow introduced into the sealed container, and the recorder 17
Determine the setting value for.

FIG. 2 is a longitudinal sectional view showing another embodiment of the device of the present invention. Honji/11! In the example, the device is installed such that its upper end is below the water level of the microalgae culture tank.

In this device, the means for controlling the gas-liquid contact area in the closed container 1 is a pipe 36 serving as a flow path for guiding the original gas-containing gas in the upper part of the closed container 1 into the microalgae suspension in the lower part of the closed container 1.
, a pipe 38, and a blower 35 as a means for circulating the carbon dioxide-containing gas above the airtight container 1 into the microalgae suspension below the airtight container 1 through the flow path; It consists of an aeration device 40 provided in the inner opening and a means for controlling the circulating supply amount of carbon dioxide-containing gas according to the carbon dioxide concentration in the closed container 1 or in the pipe 3 as the extraction flow path. This differs from the device shown in FIG.

A pipe 36 for taking out the carbon dioxide-containing gas in the gas phase G branches into a pipe 37 and a pipe 38, the pipe 36 opens upward into the closed container 1, and the pipe 38 branches again and opens downward into the closed container 1, respectively. It's open.

A control valve 34 and a control valve 33 for adjusting the flow rate are connected to the pipe 37 and the pipe 38, respectively.
and in tube 38. A diffuser 40 for gas dispersion is provided at the tip of the branched pipe 38, and a sequence valve 39 that opens and closes sequentially in response to changes in the flow rate within the pipe 38 is provided in the branched pipe. A dissolved carbon dioxide measuring device 15 is disposed in the liquid phase chamber in the lower part of the sealed container 1, and is connected to the flow rate control valve 3 via a carbon dioxide gas analyzer 16 and a recording controller 17.
4 and the flow rate control valve 33. Carbon dioxide measuring device 15
detects dissolved carbon dioxide in the minute algae suspension and sends a signal to the analyzer 16. Analyzer 16 then records controller 1γ
It sends a signal to flow control valve 34 and flow control valve 33.
Adjust. If the dissolved carbon dioxide concentration is lower than the set value, the flow control valve 33 is further opened and the flow control valve 34 is further closed. As a result, the sequence valve 39 is sequentially opened in accordance with the flow rate, and the amount of circulating and supplied carbon dioxide-containing gas into the microalgae suspension increases, the gas-liquid contact area increases, and the amount of carbon dioxide gas added increases. Conversely, if the dissolved carbon dioxide Wi degree is higher than the set value, the flow rate control valve 33 is further closed;
4 can be heard further. As a result, the sequence valve 39 is sequentially closed according to the flow rate, and the amount of circulating gas containing carbon dioxide gas supplied into the microalgae suspension is reduced, the gas-liquid contact area is reduced, and the amount of carbon dioxide gas added is reduced. Setting values of the recording controller 17 can be changed as necessary.

FIG. 3 is a longitudinal sectional view showing still another embodiment of the apparatus of the present invention. In this example, the device is installed so that its upper end is below the water surface of the microalgae culture tank. In this device, the means for controlling the gas-liquid contact area in the closed container 1 is a pipe 4 serving as a flow path that guides the microalgae suspension in the lower part of the closed container 1 into the carbon dioxide gas-containing gas in the upper part of the closed container 1.
1, a pipe 44, and a pump 42 as a means for circulating and supplying the microalgae suspension in the lower part of the closed container 1 through the flow path into the carbon dioxide-containing gas in the upper part of the closed container 1; the closed container 1 of the flow path; Consists of a liquid atomizing device 47 provided at the inner opening and means for controlling the circulating supply amount of the fine 9X suspension according to the carbon dioxide concentration in the closed container 1 or in the pipe 3 as the extraction flow path. This differs from the apparatus shown in FIGS. 1 and 2 in that the apparatus shown in FIG. A pipe 41 for taking out the microalgae suspension in the liquid phase tank branches into a pipe 43 and a pipe 44.
3 E opens downward into the closed container 1, and the tubes 44 branch again and open upward into the closed container 1, respectively. A control valve 46 and a control valve 45 are installed in the pipe 43 and the pipe 44, respectively, for adjusting the respective flow rates. An atomizer 47 for liquid injection is provided at the tip of the branched pipe 44, and a sequence valve 48 is provided in the branched pipe to open and close sequentially in response to changes in the flow rate within the pipe 44. ing. A dissolved carbon dioxide measuring device 15 is arranged in the liquid phase chamber in the lower part of the sealed container 1, and the dissolved carbon dioxide measuring device 15 is connected to the flow rate control valve 45 and the flow rate control valve 4 via a carbon dioxide gas analyzer 16 and a recording controller 17.
Connect to 6. Carbon dioxide measuring device 15 is microalgae! g Dissolved carbon dioxide gas in the turbid liquid is detected and a signal is sent to analyzer 1G. Analyzer 16 then sends a signal to recording controller 17 which controls flow control valve 45 and flow control valve 46. If the dissolved carbon dioxide m degrees is lower than the set value, the flow control valve 45 is further opened and the flow control valve 46 is further closed. As a result, the sequence valve 48 is sequentially opened in accordance with the flow rate, and the amount of microalgae suspension sprayed into the gas phase G increases, the gas-liquid contact area increases, and the amount of carbon dioxide gas added increases. Conversely, if the dissolved carbon dioxide concentration is higher than the set value, the flow control valve 45 is further closed and the flow control valve 46 is further closed. As a result, the sequence valve 48 is sequentially closed according to the flow rate, and the amount of microalgae suspension sprayed into the gas phase G is reduced, and the gas-liquid contact area is reduced.
The amount of carbon dioxide added decreases. Setting values of the recording controller 17 can be changed as necessary.

Next, there are matters to be noted in the present invention.

In the above embodiment, the device is installed so that its upper end is below the water surface of the microalgae culture tank, but the device is installed so that most of the device is above the water surface of the microalgae culture tank. In this case, a control valve may be provided in the pipe 3 to close the pipe 3 when the control valve 10 is opened and to open the pipe 3 when the control valve 10 is opened.

The floating plate 31 limits the contact area between the gas phase G and the liquid phase and reduces the lower limit of the gas-liquid contact area in the closed container, so the control range of the gas-liquid contact area becomes wider, but this is not a necessary condition.

Control valve 1 consisting of carbon dioxide analyzer 11 and recording controller 12
0's control means are a carbon dioxide gas measuring device 15 and a carbon dioxide gas analyzer 1.
It can also be constructed by connecting a circuit similar to the circuit consisting of the control valve 6 and the recording controller 17 to the control valve 1. In this case, the set value for opening the control valve 10 may be smaller than the set value for controlling the carbon dioxide concentration in the microalgae suspension taken out through the pipe 3 to the recording controller 17.

Since the series of operation patterns of the present device at any set value for the recording controller 17 are constant under conditions where the carbon dioxide concentration in the microalgae suspension to be introduced is constant,
It is also easy to understand this movement pattern in advance through another experiment and to perform forward control using a timer or the like. The apparatus of this embodiment can handle cases where the carbon dioxide a degree in the microalgae suspension to be introduced is not constant.

During the first operation, the liquid level S rises due to a decrease in the volume of the gas phase G. The liquid level S can also be kept constant by compensating for this decrease by continuous injection of carbon dioxide-containing gas.

Although this is not a necessary condition of the invention, it is possible to avoid reducing the number of said second operations. It is effective to use liquefied carbon dioxide as the carbon dioxide-containing gas for replenishment.

Furthermore, when applying the present invention to microalgae culture, the culture tank 8
In order to prevent foaming that may cause carbon dioxide, it is important to quickly dilute the microalgae suspension to which carbon dioxide gas has been added in the culture tank 8. For this purpose, it is necessary to open the tube 3 into the liquid at many different points in the culture tank 8 and to give an appropriate flow to the liquid in the culture tank.

Again, since the present invention is constructed as described above, it has the following advantages.

(1) During the addition of carbon dioxide gas, the carbon dioxide-containing gas is not released outside the container and is completely dissolved in the microalgae suspension, so there is little loss of carbon dioxide gas.

(E) Since the gas-liquid contact area in the sealed container is adjusted according to the degree of carbon dioxide in the carbon dioxide-containing gas in the sealed container, it is possible to dissolve carbon dioxide for a certain amount of time as necessary.

(Force) There is no particular restriction on the concentration of carbon dioxide in the carbon dioxide-containing gas to be introduced, and gases with various concentrations of carbon dioxide can be used.

As described above, if the present invention is applied to microalgae culture, it becomes possible to produce algae at a very low cost.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view showing an embodiment of vtiδ of the present invention,
FIG. 2 is a longitudinal cross-sectional view showing another embodiment of the apparatus of the present invention, and FIG. 3 is a longitudinal cross-sectional view showing another embodiment of the apparatus of the present invention, in which the upper end of the apparatus is a microalgae culture tank. This applies when the water is located below the water surface. 1 is a closed container, 2 is a tube, 2a is a tube, 2b is a tube, 3 is a tube,
4 is a pipe, 5 is a carbon dioxide-containing gas source, 6 is a compressor, 7 is a pipe, 8 is a microalgae culture tank, 9 is a pump, 10 is a control valve, 11 is a carbon dioxide gas analyzer, 12 is a recording controller, 13
14 is a contact, 15 is a carbon dioxide gas measuring device, 16 is a carbon dioxide gas analyzer, 17 is a recording controller, 18 is a controller, 19
is a meteor control valve, 20 is a flow control valve, 21 is a sequence valve, 22 is an atomizer, 23 is a contact, 24 is a contact, 25 is a controller, 26 is a check valve, 27 is a check valve, 28 is a reverse stop valve, 29 dehumidifier, 30 pump, 31 floating plate, 32
33 is a flow control valve; 34 is a flow control valve; 35
is a blower, 136 is a pipe, 37 is a pipe, 38 is a pipe, 39 is a sequence valve, 40 is a diffuser, 41 is a pipe, 42 is a pump, 43 is a pipe, 44 is a pipe, 45 is a flow rate control valve, 46 is a A flow control valve, 47 is an atomizer, and 48 is a sequence valve.

Claims (1)

[Claims] 1. The supply of carbon dioxide gas to the microalgae suspension is carried out by (a) at least a portion of the microalgae suspension in a tank where microalgae are cultured under light irradiation conditions; is sent into a closed container filled with a gas containing carbon dioxide gas, and the microalgae suspension is brought into contact with the gas containing carbon dioxide gas in the closed container, so that carbon dioxide gas is dissolved in the microalgae suspension. (b) When the carbon dioxide concentration in the sealed container has decreased to a predetermined value, the upper part of the sealed container is sealed. By opening the communication port that communicates with the outside of the container and introducing the microalgae suspension into the closed container, the low concentration carbon dioxide-containing gas is pushed out of the closed container, and then the communication port is closed and the closed container is closed. This is carried out by repeating the second operation of introducing new carbon dioxide-containing gas into the sealed container while discharging the microalgae suspension to the outside, and thereby filling the sealed container with the newly adjusted carbon dioxide-containing gas. Also, a method for supplying carbon dioxide gas to a microalgae suspension, characterized in that, in the first operation, the amount of dissolved carbon dioxide gas is adjusted by adjusting the gas-liquid contact area in the closed container. 2. During the first operation, at least a portion of the microalgae suspension in the tank where microalgae are being cultured under light irradiation conditions is introduced into a closed container filled with carbon dioxide-containing gas. In this case, the microalgae suspension is sprayed and introduced from above into the sealed container, and the air-liquid contact area in the sealed container is adjusted by adjusting the time between the spray introductions. A method for supplying carbon dioxide gas to the microalgae suspension according to item 1. 3. During the first operation, the carbon dioxide-containing gas filled in the sealed container is taken out and circulated as fine bubbles into the liquid in the lower part of the sealed container, and the amount of circulating supply is adjusted to achieve gas-liquid contact. A method for supplying carbon dioxide gas to a microalgae suspension according to claim 1, which comprises adjusting the area. 4. During the first operation, by circulating and supplying the microalgae suspension in the lower part of the sealed container to the carbon dioxide gas-containing gas in the upper part of the sealed container as a fine liquid mass, and adjusting the circulating supply amount, The method for supplying carbon dioxide gas to a microalgae suspension according to claim 1, characterized in that the gas-liquid contact area is adjusted. 5. In an apparatus for supplying carbon dioxide gas to a microalgae suspension, (c) an airtight container capable of holding a carbon dioxide gas-containing gas above and a microalgae suspension below; (d) microalgae in the airtight container; A channel for introducing the algae suspension, (e) a channel for taking out the microalgae suspension from the bottom of the sealed container to the outside of the sealed container, (f) a communication port that communicates the upper part of the inside of the sealed container with the outside of the sealed container, (g ) Means for introducing carbon dioxide-containing gas into a closed container, (
h) the channel for introducing the microalgae suspension into the closed container;
forced flow means for forming a flow of the microalgae suspension that sequentially passes through the channel for taking out the microalgae suspension from inside the closed container and from below the closed container to the outside of the closed container; (i) the communication port; (j) opening the communication port when the carbon dioxide concentration in the sealed container has decreased to a predetermined value;
By introducing the microalgae suspension into the sealed container, the low concentration carbon dioxide-containing gas is pushed out of the sealed container, and then the communication port is closed to introduce new carbon dioxide-containing gas into the sealed container. (k) means for controlling the means to operate for a certain period of time, and (k) means for controlling the gas-liquid contact area in the closed container in response to changes in the concentration of carbon dioxide gas in the closed container to adjust the amount of dissolved carbon dioxide gas. An apparatus for supplying carbon dioxide gas to a microalgae suspension, characterized by comprising means. 6. When the carbon dioxide concentration in the sealed container has decreased to a predetermined value, the communication port is opened and the microalgae suspension is introduced into the sealed container, thereby sealing the gas containing low concentration carbon dioxide. After the gas is pushed out of the container, the communication port is closed and the means for introducing new carbon dioxide gas into the sealed container is controlled to operate for a certain period of time, wherein the carbon dioxide concentration in the sealed container is set to a predetermined value. The means for controlling the communication port to open when the temperature decreases to 100% is comprised of a carbon dioxide analyzer that continuously takes out the carbon dioxide-containing gas in the closed container and analyzes the carbon dioxide. 6. The device for supplying carbon dioxide gas to a microalgae suspension according to claim 5, wherein the device is suitably connected to a control means that opens the communication port in response to a signal. 7. One end of the channel for introducing the microalgae suspension into the sealed container is opened above the sealed container, and a means for controlling the air-liquid contact area in the sealed container is provided at the opening. A patent claim comprising: an atomizing device for spraying the suspension as a fine liquid mass; and means for controlling the amount of the microalgae suspension sprayed according to the carbon dioxide concentration in the closed container. A device for supplying carbon dioxide gas to the microalgae suspension according to item 5 or 6. 8. The means for controlling the amount of spraying of the microalgae suspension according to the carbon dioxide concentration in the hermetically sealed container is located in the channel for taking out the microalgae suspension from below the hermetically sealed container or in the lower part of the hermetically sealed container. It consists of a carbon dioxide measuring device placed in a microalgae suspension and effective for measuring dissolved carbon dioxide in the liquid, and the measuring device responds to signals from a carbon dioxide analyzer and a carbon dioxide measuring device. The microalgae suspension according to claim 7 is suitably connected to a control means for controlling the amount of spraying of the microalgae suspension into the closed container. A device that supplies 9. The means for controlling the gas-liquid contact area in the sealed container is a channel for guiding the carbon dioxide-containing gas in the upper part of the sealed container into the microalgae suspension in the lower part of the sealed container; means for circulating and supplying the carbon dioxide-containing gas into the microalgae suspension in the lower part of the closed container, an aeration device provided at the opening of the channel in the sealed container, and inside the sealed container or in the take-out channel. Supplying carbon dioxide gas to the microalgae suspension according to claim 5 or 6, characterized in that the method comprises means for controlling the circulating supply amount of the carbon dioxide-containing gas according to the carbon dioxide concentration of the microalgae suspension. Device. 10. A means for controlling the circulating supply amount of carbon dioxide-containing gas according to the carbon dioxide concentration in the closed container or in the take-out flow path is provided in the flow path for taking out the microalgae suspension from below the closed container to the outside of the closed container. Or, it consists of a carbon dioxide measuring device that is placed in the microalgae suspension in the lower part of the sealed container and is effective for measuring dissolved carbon dioxide in the liquid, and the measuring device is a carbon dioxide gas analyzer and a carbon dioxide gas measuring device. Claim 9, characterized in that the device is appropriately connected to a control means for controlling the circulating supply amount of carbon dioxide gas-containing gas in accordance with a signal from the device.
A device for supplying carbon dioxide gas to the microalgae suspension described in 2. 11. The means for controlling the gas-liquid contact area in the sealed container includes a channel for guiding the microalgae suspension in the lower part of the sealed container into the carbon dioxide gas-containing gas in the upper part of the sealed container; means for circulating and supplying the microalgae suspension into the carbon dioxide-containing gas above the airtight container, a liquid atomizer provided at the opening in the airtight container of the channel, and a liquid atomizer provided in the airtight container or the extraction channel. Supplying carbon dioxide gas to the microalgae suspension according to claim 5 or 6, characterized by comprising means for controlling the circulating supply amount of the microalgae suspension according to the carbon dioxide concentration of the microalgae suspension. device to do. 12. The means for controlling the circulation supply amount of the microalgae suspension according to the carbon dioxide concentration in the closed container or in the take-out channel is a flow for taking out the microalgae suspension from below the closed container to the outside of the closed container. It consists of a carbon dioxide measuring device that is placed in the microalgae suspension inside the road or in the lower part of the closed container and is effective for measuring dissolved carbon dioxide in the liquid, and the measuring device is a carbon dioxide gas analyzer and a carbon dioxide gas analyzer. Claim 11, characterized in that the device is suitably connected to a control means for controlling the circulating supply amount of the microalgae suspension in response to a signal from a gas measuring device.
A device for supplying carbon dioxide gas to the microalgae suspension described in 2.