JPH0731466A - Method for environmental control and apparatus therefor - Google Patents

Abstract

PURPOSE:To provide a method for the environmental control in which evolved gaseous carbon dioxide in a closed space can economically be recovered and oxygen can be generated to control the gaseous carbon dioxide and oxygen in air to constant concentrations. CONSTITUTION:This environmental controller is equipped with a photosynthetic reactional vessel 6 for culturing an oxygen generating type photosynthetic organism, a light source 21 for feeding light thereto, a feeding system 1 for air to be treated and a discharging system 2 for the treated air. In the controller, a mechanism 8 for changing the amount of energy is installed in the light source for feeding the light and devices 5 and 7 for measuring the gaseous carbon dioxide and oxygen concentrations in air are provided in the feeding system for the air to be treated and/or the discharging system for the treated air. Furthermore, a controller 9 for controlling the mechanism 8 for changing the amount of the light energy by values measured with the devices for measurement is installed to change the amount of the light energy to be fed to the oxygen generating type photosynthetic organism and modulate the rate of conversion from gaseous carbon dioxide into oxygen. Thereby, the control is performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for controlling the atmospheric environment, and more particularly to a technique for controlling the carbon dioxide concentration and oxygen concentration in the air by an oxygen-producing photosynthetic organism in a closed space.

[0002]

2. Description of the Related Art In a closed space such as a spacecraft, a submarine, or an ocean development space, or in a quasi-closed space such as a residential space on the ground or in a building, or an underground parking lot, carbon dioxide in human breath or combustion exhaust gas It is essential to control the atmospheric environment by removing the gas and supplementing the oxygen used for breathing or combustion to keep the carbon dioxide concentration and oxygen concentration in the air at a constant concentration. In a residential space in a building or a semi-closed space such as an underground parking lot, this is usually achieved by ventilation with outside air. On the other hand, in spacecraft and submarines, the carbon dioxide gas generated in the closed space is absorbed and separated using chemicals and discharged to the outside of the space, and the oxygen gas is supplied by electrolysis of water or liquid oxygen brought in beforehand to replenish the space. The method of controlling the concentration of carbon dioxide gas and the concentration of oxygen in the air is adopted.

However, since the air pollution is progressing more and more in urban areas in recent years, it is necessary to clean the outside air introduced for the purpose of ventilation, and the cost of controlling the atmospheric environment by ventilation is rising. Also in the use of underground space, it is expected that the energy and cost required for ventilation will increase as deep underground development progresses. Furthermore, carbon dioxide is the main causative agent of global warming, which has the greatest impact among global environmental problems, and it is considered necessary to review the ventilation system that releases the generated carbon dioxide into the atmosphere. There is.

On the other hand, the carbon dioxide removal / oxygen supply system adopted in spacecraft and submarines has problems that waste is generated along with the removal of carbon dioxide and a large amount of energy is required. It is estimated that the cost of transporting necessary chemicals and liquid oxygen will reach enormous amounts, especially for spacecraft that carry out long-term manned flights such as planetary exploration. Further, in the chemical oxygen supply method, on the contrary, there is a concern that there may be damage due to excess oxygen.
On the other hand, as a method for economically recovering the carbon dioxide gas generated in the closed space and effectively utilizing it to generate oxygen, a method using plant cells or microalgae having photosynthetic ability has already been proposed. (Japanese Patent Application No. 1-155858)
issue).

[0005]

DISCLOSURE OF THE INVENTION The present invention relates to an improvement in the method of utilizing the above oxygen-producing photosynthetic organisms, wherein carbon dioxide gas generated in a closed space is economically recovered to generate oxygen,
It is an object of the present invention to provide an environment control method and device capable of controlling the concentration of carbon dioxide gas and the concentration of oxygen in air to constant concentrations.

[0006]

In order to solve the above problems, the present invention provides a method for controlling an environment in which the concentration of carbon dioxide and / or oxygen in the air is adjusted by an oxygen-producing photosynthetic organism. The concentration and / or the oxygen concentration is controlled by changing the amount of light energy supplied to the oxygen-generating photosynthetic organism and adjusting the conversion rate of carbon dioxide gas to oxygen.

In the above control method, the change in the amount of light energy supplied to the oxygen-producing photosynthetic organism is adjusted by adjusting the irradiation intensity within the irradiation intensity range in which the photosynthetic activity of the oxygen-producing photosynthetic organism is favorably maintained. Alternatively, the amount of light energy supplied per unit time may be changed by adjusting the irradiation time with an irradiation intensity that maintains the photosynthetic activity of the oxygen-producing photosynthetic organism at a good intensity.

The change in the amount of light energy supplied to the oxygen-generating photosynthetic organisms is determined by the concentration of carbon dioxide and / or oxygen in the air to be treated and the concentration of carbon dioxide and / or oxygen in the treated air. Detecting the ability of the oxygen-generating photosynthetic organism to convert carbon dioxide gas to oxygen per unit time so that the carbon dioxide concentration and the oxygen concentration in the treated air or the air in the treatment target space are maintained at predetermined values. It is preferable to change the amount of light energy supplied to the photosynthetic organism.

Further, according to the present invention, the photosynthetic reaction tank for culturing the oxygen-producing photosynthetic organism, the light source for supplying light to the photosynthetic reaction tank, the treated air supply system, and the treated air discharge system are provided in the environment control device, and the light is supplied. The light source is provided with a mechanism for changing the amount of light energy, and a device for measuring the carbon dioxide concentration and oxygen concentration in the air is provided in the air supply system for treatment and / or the exhaust system for treatment air, and the measurement value of the measurement device is provided. Therefore, a control device for controlling a mechanism for changing the amount of light energy is provided.

In the above apparatus, the mechanism for changing the amount of light energy is preferably a mechanism capable of adjusting the irradiation intensity and / or the irradiation time. Further, by providing the photosynthesis reaction tanks in multiple stages, the air to be treated can be continuously treated to precisely control the carbon dioxide concentration and the oxygen concentration in the air. As described above, the present invention has a remarkable relationship between the change in the conversion rate of carbon dioxide gas to oxygen or the conversion rate of oxygen to carbon dioxide gas and the change in the amount of light energy supplied to the oxygen-producing photosynthetic organism. It was discovered that there is.

The environment control method and apparatus of the present invention will be described in more detail below. The environmental control device of the present invention is a photosynthetic reaction tank for culturing oxygen-producing photosynthetic organisms, a light source for supplying light thereto and a treated air supply system, a treated air discharge system, a medium supply system, a surplus algal cell recovery system and measurement control. It consists of a system. As the oxygen-producing photosynthetic organism to be cultured in the photosynthetic reaction tank of the present invention, any one can be used as long as it grows in a medium to high temperature range, and specific examples include green algae, cyanobacteria, diatoms and Euglena. Microalgae such as flame-colored algae, true-eye spot algae, primesio algae, cryptoalgae, and red algae are preferable, but oxygen-producing photosynthetic bacteria, seaweeds, and general plants can also be applied.

The light source used for the photosynthetic reaction may be any one as long as the oxygen-producing photosynthetic organism photosynthesizes, and specific examples thereof include sunlight, white light, fluorescence and the like. As a method of introducing light into the photosynthetic reaction tank, the method of irradiating from outside through the outer wall of the light-transmitting reaction tank can also be used to collect light from the light source, transmit it with an optical fiber, and diffuse it into the culture solution through the light diffuser. Either an irradiation method or an internal irradiation method in which a light source is installed in the culture tank may be used. The control of the supply of the light energy may be performed by turning the light source on and off or by the strength. Further, the culture solution or the like may be circulated in a light place and a dark place, and the circulation rate may be controlled, or another method may be used. The environmental control device of the present invention can adjust the amount of oxygen generated according to the fluctuation of the carbon dioxide concentration in the air in the closed space, and can control the carbon dioxide and oxygen concentrations to be constant.

[0013]

[Function] Oxygen-producing photosynthetic organisms such as plants and algae use light energy to produce organic substances such as carbohydrates and oxygen from carbon dioxide and water as shown in formula (1). _{6CO 2 + 12H 2 O → 6O} 2 + C 6 H 12 O 6 + 6H 2 O (1) In other words, if use of these photosynthetic organisms, removal and oxygen a carbon dioxide gas in the reaction vessel (CO ₂₎ of the (O ₂₎ Occurrence can be achieved at the same time. In particular, since microalgae have high photosynthetic activity and the amount of biomass per unit volume is higher than that of higher plants, this reaction is most useful for economically recovering carbon dioxide and generating oxygen. It is suitable. In addition, organic matter produced at the same time as oxygen is recovered as useful organic matter such as algal cells or polysaccharides and organic acids. Algal cells are effectively used as food and feed, feed or fertilizer, and polysaccharides and organic acids are effectively used as industrial raw materials. Can be used. Further, as it is understood from the above equation (1), since the O ₂ feed to the system is equivalent to the CO ₂ reduction, O ₂
Alternatively, the activity of the photosynthetic organism can be grasped by monitoring either the CO ₂ concentration.

The photosynthetic activity of the photosynthetic reaction tank, that is, the rate of carbon dioxide absorption and oxygen generation is determined by the concentration of algal cells, the photosynthetic activity per cell and the amount of light energy supplied.
The photosynthetic activity per cell is determined by the total chlorophyll content, chlorophyll a / chlorophyll b or c ratio, etc., but this value is determined by the combined action of various culture conditions such as culture temperature, pH conditions, and light irradiation conditions. Because it is done
It is not practical to control the carbon dioxide absorption and oxygen generation rate in the photosynthetic reaction tank by using the photosynthetic activity per cell as an operation factor.

By changing the algal cell concentration,
In the method of controlling the carbon dioxide absorption and oxygen generation rate of the photosynthesis reaction tank, it takes time to adjust the concentration of algal cells, and it is necessary to have a tank that stores algal cells withdrawn from the photosynthetic reaction tank while maintaining photosynthetic activity. However, there is a problem that the device becomes complicated. Therefore, the method of adjusting the amount of light energy supplied to the reaction tank is the best method for controlling the carbon dioxide absorption and the oxygen generation rate of the photosynthesis reaction tank. Therefore, in the present invention, the photosynthetic biological activity is controlled by the control system having the O ₂ or CO ₂ gas concentration as the input variable and the light energy supply amount as the output variable.

In general, a photosynthetic organism has an optimum irradiation intensity range of light for performing photosynthesis. It is well known that when the irradiation intensity exceeds a certain value, cells undergo strong light inhibition and die, but in reducing the light energy supply, the irradiation intensity does not reach a certain value by reducing the irradiation intensity. In this case, the photosynthetic activity per cell is remarkably reduced, whereas when the light energy supply is reduced by adjusting the irradiation time while maintaining the irradiation intensity at an intensity suitable for the algae, The photosynthetic activity around the area remains high.

Table 1 shows the photosynthetic activity of microalgae (chlorella) under light irradiation conditions.

[Table 1]

As described above, when the amount of light energy supplied is adjusted by adjusting the irradiation time, the photosynthetic activity remains high. Further, in the present invention, when the carbon dioxide concentration fluctuation in the air to be treated is rapid and significant, a plurality of photosynthetic reaction tanks are installed, and the air to be treated is treated in multiple stages in these reaction tanks to obtain It is possible to precisely control the carbon dioxide and oxygen concentrations. Although the description has been given here using the microalgae, the present invention does not limit the target organisms to this.

[0019]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. Example 1 FIG. 1 is a flow sheet of an environment control device incorporating a photosynthetic reaction tank. In FIG. 1, the air to be treated 1 sent from the closed space to be treated is sterilized by a sterilization filter 3 and fine particles are removed, and then supplied to a photosynthesis reaction tank 6. Since the air to be treated is repeatedly introduced into the photosynthesis reaction tank through the gas circulation system 15, the efficiency of dissolving carbon dioxide gas in the culture solution is significantly enhanced. A part of the air in the photosynthetic reaction tank is returned to the closed system space 16 to be treated as treated air 2 through the sterilization filter. At this time, the controller controls the O in the gas.
_{2 If the} concentration becomes 21%, flow meter valve 4
Is open and below that, gas is circulated in the system.

The carbon dioxide concentration and / or the oxygen concentration in the air to be treated and the treated air or the air in the closed system space to be treated are analyzed by the gas analyzers 5 and 7, and the analyzed values are taken in by the measurement control computer 9. Analyze with. Based on this analysis, the light source turn-on / off time of the photosynthesis reaction tank, the number of light sources turned on, the amount of treated air supplied, the amount of treated air discharged, and the amount of gas circulated are controlled, and the concentration of carbon dioxide and / or oxygen in the treated air is controlled. Even if fluctuates, the carbon dioxide concentration and / or the oxygen concentration in the air to be treated or the air in the closed space to be treated can be controlled within a predetermined range.

The water temperature, pH, absorbance, etc. of the culture solution can be constantly measured by the sensor 8 and the analysis value can be taken in by the measurement control computer to control the water temperature adjusting device, the pH adjusting device and the like. Further, the culture solution is appropriately withdrawn as the surplus algal cells 14 so that the absorbance of the culture solution becomes constant, and the same amount of the medium 1
By supplying 0, the concentration of microalgae in the photosynthesis reaction tank can be maintained constant. In the photosynthesis reaction tank 6,
As a light source, a plurality of fluorescent lamps 21 are used, and they are turned on independently
The light can be controlled to be turned off, the light from the light source is supplied to the microalgae culture liquid 23 through the glass 22, the heat generated from the fluorescent lamp is discharged to the outside of the tank by the exhaust heat fan 24, and the cooling air is supplied from the ventilation hole 25 at the bottom of the tank. It is configured to be supplied with air.

Example 2 FIG. 2 is a schematic view of the environment control apparatus shown in FIG. 1 in which a plurality of photosynthetic reaction tanks are installed and multi-stage treatment of air to be treated is performed. It is explanatory drawing which was excerpted and shown. In this device, even if the carbon dioxide concentration and / or the oxygen concentration in the air to be treated fluctuate greatly, it is sufficient to absorb the fluctuations in a plurality of reaction tanks. The gas concentration and / or the oxygen concentration can be controlled more precisely within a predetermined range. Reference numerals in FIG. 2 are the same as those in FIG.

Example 3 A treatment experiment was conducted using an environment control experimental apparatus (photosynthesis reaction tank effective volume 10 liters) having the configuration shown in FIG. The air to be treated was a mixture of air and carbon dioxide gas supplied from a carbon dioxide gas cylinder using a mass flow meter so that the concentration of carbon dioxide gas was predetermined. Chlorella, a kind of green algae, was used as the microalgae responsible for the photosynthetic reaction. The experiment was carried out under four conditions in which the concentration of carbon dioxide in the air to be treated was constant (RUNI and RUN2) and when the concentration of carbon dioxide in the air to be treated was varied (RUN3 and RUN4).

Under any of the experimental conditions, the concentration of carbon dioxide gas in the air to be treated was measured by the raw gas concentration measuring system 5 and the concentration of carbon dioxide gas in the treated air was measured by the exhaust gas concentration measuring system 7, and the measurement data was taken in by the computer 9. The number of lit fluorescent lamps 21 was changed according to the amount of carbon dioxide gas reduction per unit time, and the photosynthetic rate was controlled so that the carbon dioxide concentration of the treated air was 0.05% or less. The pH of the culture solution 23 was controlled to be constant. Table 2 shows the results of the experiment in which the carbon dioxide concentration of the air to be treated was kept constant, and Table 3 shows the results of the experiment in which the carbon dioxide concentration of the air to be treated was varied. In either case, the concentration of carbon dioxide in the treated air could be kept low.

[0025]

[Table 2]

[0026]

[Table 3]

[0027]

According to the method of the present invention, the carbon dioxide gas generated in the closed space can be economically recovered, oxygen can be generated, and the carbon dioxide concentration and the oxygen concentration in the air can be controlled to a constant concentration. The energy cost required for environmental control in a closed space can be greatly improved by a simple operation. When applied to a life-supporting system in a closed space, surplus algal cells recovered from the photosynthetic reaction tank should be effectively used as food, feed or feed, and photosynthetic products such as polysaccharides and organic acids should be effectively used as food ingredients. Therefore, environmental control and food production can be achieved at the same time, and energy consumption in the life support system can be reduced.

[Brief description of drawings]

FIG. 1 is a flow sheet of an environment control device of the present invention.

FIG. 2 is a schematic configuration diagram of a multistage photosynthetic reaction tank used in the present invention.

[Explanation of symbols]

1: treated air, 2: treated air, 3: sterilizing filter,
4: Flow meter valve, 5: Raw gas concentration measurement system,
6: Photosynthesis reaction tank, 7: Exhaust gas concentration measurement system, 8: Various sensors, 9: Computer for measurement control, 10: Medium, 1
1: Pump, 12: Cooler, 13: Dehumidifier, 14: Excess algal cells, 15: Gas circulation system, 16: Closed space, 21: Fluorescent lamp, 22: Glass, 23: Microalgal culture solution, 24: Exhaust Heat fan, 25: ventilation hole

Claims (6)

[Claims] 1. A method for controlling an atmospheric environment, wherein the carbon dioxide concentration and / or oxygen concentration in the air is adjusted by an oxygen-producing photosynthetic organism, wherein the carbon dioxide concentration and / or oxygen concentration is supplied to the oxygen-producing photosynthetic organism. An environmental control method comprising controlling by changing the amount of light energy to be generated and adjusting the conversion rate of carbon dioxide gas to oxygen. 2. The change in the amount of light energy supplied to the oxygen-producing photosynthetic organism is adjusted by adjusting the irradiation intensity within the irradiation intensity range in which the photosynthetic activity of the oxygen-producing photosynthetic organism is favorably maintained, or 2. The amount of light energy supplied per unit time is changed by adjusting the irradiation time with an irradiation intensity at which the photosynthetic activity of the oxygen-producing photosynthetic organism is maintained at a good intensity. Environmental control method. 3. The change in the amount of light energy supplied to the oxygen-generating photosynthetic organism is determined from the carbon dioxide concentration and / or oxygen concentration in the air to be treated and the carbon dioxide concentration and / or oxygen concentration in the treated air. Detecting the ability of the photosynthetic organism to convert carbon dioxide gas to oxygen per unit time so that the carbon dioxide concentration and the oxygen concentration in the treated air or the air in the treated space are maintained at predetermined values. The environment control method according to claim 1, wherein the method is performed by changing the amount of light energy supplied to the living thing. 4. A photosynthetic reaction vessel for culturing an oxygen-producing photosynthetic organism, an environment control device having a light source for supplying light thereto, a treated air supply system, and a treated air discharge system, wherein light is supplied to the light source. A mechanism for changing the amount of energy is provided, and a device for measuring the concentration of carbon dioxide gas and oxygen concentration in the air is provided in the treated air supply system and / or the treated air discharge system, and the amount of light energy is measured by the measurement value of the measurement device. An environment control device comprising a control device for controlling a mechanism for changing the temperature. 5. The environment control apparatus according to claim 4, wherein the mechanism for changing the amount of light energy is an irradiation intensity adjusting mechanism and / or an irradiation time adjusting mechanism. 6. The environment control device according to claim 4, wherein the photosynthesis reaction tanks are provided in multiple stages.