JP7511272B2 - CO2 separation method and plant growth method - Google Patents

Description

This article relates to a method for separating CO2 from used septic tanks, and more specifically, to a method for separating and capturing CO2 from adsorbents in septic tanks used for drain purification, and for cultivating plants using exhaust gas containing the captured CO2.

In compressed air circuits, the drain generated when removing foreign matter from compressed air contains foreign matter such as oil, as well as CO2 dissolved in large amounts due to the pressure of the compressed air. Therefore, when the drain is purified in a septic tank that removes foreign matter, CO2 is also separated and removed in addition to the foreign matter. When the septic tank needs replacing due to a predetermined period of time, the adsorbent material filled in it is removed, disassembled, cleaned, and reused, and the removed adsorbent material containing a large amount of foreign matter is incinerated.

When disassembling and cleaning the tank, the air pressure inside the tank drops compared to when it is in use, causing the CO2 adsorbed in the adsorbent to be released to the outside. In addition, there was a problem in that CO2 was also released when the adsorbent itself was incinerated.

In order to solve the above problems, a technical proposal has been made as described in Japanese Patent No. 6247788 (Patent Document 1). That is, Patent Document 1 describes a technology in which the temperature of a CO2 adsorbent is increased by a direct heating method in which the CO2 adsorbent is brought into contact with high-temperature steam, and the CO2 adsorbed in the adsorbent is separated and captured.
However, the technical proposal described in Patent Document 1 is intended to desorb CO2 in exhaust gas. If this proposal were to be adopted in the present problem where the adsorbent is already wetted from passing through the drain, the amount of moisture adhering to the adsorbent would be further increased by spraying high-temperature steam onto the adsorbent, and the amount of heat required to condense the moisture would also be increased, making it difficult to adopt this proposal in the present invention.

In order to solve the above problem, the applicant discovered that when compressed air was sent to the inlet of a septic tank that was due for replacement, the CO2 concentration in the compressed air discharged from the outlet was higher than that at the time of inflow. Furthermore, when high-concentration nitrogen was sent to the inlet, it was confirmed that CO2 was simultaneously discharged from the outlet in addition to nitrogen gas.

Based on the idea that it might be possible to recover the adsorbed CO2 before the adsorbent is incinerated, we focused on the above phenomenon in which the CO2 adsorbed in the adsorbent is desorbed to a certain extent by pressurized air, and developed a CO2 separation method in which compressed gas is introduced into a used septic tank to desorb the CO2 adsorbed in the CO2 adsorbent and recover the desorbed CO2. We also developed a plant cultivation method to utilize exhaust gas containing desorbed CO2 by sending it into a planting space to promote plant growth, which led to the proposal of the "CO2 separation method and plant cultivation method" of the present invention.

Patent No. 6247788

In view of the above problems, the present invention aims to provide a CO2 separation method that injects compressed gas into a used septic tank, thereby recovering and desorbing the CO2 adsorbed in a CO2 adsorbent filled in the used septic tank, and a plant cultivation method that utilizes exhaust gas containing CO2.

In order to solve the above problems, the CO2 separation method of the present invention comprises a hollow-cylinder main body, which is a cylindrical body having a hollow portion and openings at the top and bottom, with the hollow portion filled with a foreign matter adsorbent, a bottom body having an inlet at a predetermined location and capable of closing the lower open end of the hollow-cylinder main body via a fastening means, and a lid body having an outlet at a predetermined location and capable of closing the upper open end of the hollow-cylinder main body via a fastening means, and the method employs a means for separating and recovering the CO2 adsorbed by the foreign matter adsorbent by supplying compressed gas from the inlet to a used septic tank which remains filled with the foreign matter adsorbent to which CO2 and foreign matters contained in the drain have been adsorbed, and discharging and recovering the exhaust gas which is a mixture of compressed gas and CO2 from the outlet.

The present invention also employs a method in which the compressed gas is compressed air.

Furthermore, the plant cultivation method of the present invention is a method for utilizing exhaust gas recovered by the CO2 separation method, and employs a means for promoting plant growth by supplying exhaust gas to a planting space.

Furthermore, the present invention employs a means in which the planting space is a vinyl house, a greenhouse, or a plant factory.

The CO2 separation method of the present invention has the excellent effect of reducing the amount of CO2 released into the atmosphere when the adsorbent is removed by feeding compressed gas from the inlet of a used septic tank and using the compressed gas to desorb CO2 from the foreign matter adsorbent.

In addition, according to the plant cultivation method of the present invention, by supplying exhaust gas to the planting space, plants are grown in an atmosphere with a high CO2 concentration, which promotes photosynthesis using CO2 and promotes plant growth more than in the atmosphere.

The plant cultivation method of the present invention has the excellent effect of efficiently retaining exhaust gases in an airtight space and maintaining a high CO2 concentration by using a planting space that is either a vinyl house, a greenhouse, or a plant factory.

FIG. 1 is an explanatory diagram showing an embodiment of a CO2 separation method and a plant cultivation method according to the present invention.

The greatest feature of the CO2 separation method 1 of the present invention is that compressed gas A is introduced into a used septic tank 2, thereby desorbing the CO2 adsorbed in the foreign matter adsorbent 11, and separating and recovering the CO2 as exhaust gas H, which is a mixture of compressed gas and CO2.
The greatest feature of the plant cultivation method 5 according to the present invention is that the exhaust gas H discharged by the CO2 separation method 1 is utilized within the planting space 31.
Hereinafter, an embodiment of a CO2 separation method 1 and a plant cultivation method 5 according to the present invention will be described with reference to the drawings.

The CO2 separation method 1 and plant cultivation method 5 of the present invention are not limited to the embodiments described below, but can be modified as appropriate within the scope of the technical concept of the present invention, i.e., within the scope of shapes, dimensions, materials, etc. that can achieve the same functional effects.

FIG. 1 is an explanatory diagram showing a basic embodiment of a CO2 separation method 1 and a plant cultivation method 5 according to the present invention.
The CO2 separation method 1 and plant cultivation method 5 according to the present invention are comprised of a used septic tank 2, a compressor 20, and a planting space 31.

The used septic tank 2 is a cylindrical body containing a foreign matter adsorbent 11 that adsorbs CO2 and foreign matter such as oil and dust (hereinafter simply referred to as "foreign matter").
The used septic tank 2 is composed of a hollow cylindrical body 10 with a foreign matter adsorbent 11 filled in the hollow portion, a bottom body 13 with an inlet 12, and a lid body 15 with an outlet 14, and is a septic tank disposed in a compressed air pressure circuit for the purpose of purifying drain generated in the circuit. It is a septic tank that has been determined to require replacement in accordance with standards based on the installation period, degree of adsorption, etc., and has been removed from the compressed air pressure circuit and collected.

The hollow cylinder body 10 is a cylindrical body having a hollow portion with an open top and bottom, and the hollow portion is filled with a foreign matter adsorbent 11 .
The shape of the hollow-tube body 10 is not particularly limited as long as it is a cylindrical body, and may be a cylindrical shape or a polygonal cylindrical shape. In addition, the material constituting the hollow-tube body 10 is not particularly limited, but a configuration in which a part or the whole of the hollow-tube body 10 is made of a transparent or semi-transparent material such as reinforced plastic or glass, which allows the deterioration state of the filled adsorbent to be visually observed, may be considered.

The foreign matter adsorbent 11 is filled into the hollow cylinder body 10 to adsorb CO2 and foreign matter in the drain discharged from the compressed air pressure circuit.
The material of the foreign matter adsorbent 11 may be any of various conventionally known materials capable of absorbing CO2 and foreign matter contained in the drain, such as amines, zeolite, etc. In addition, it is also possible to use an embodiment in which these materials are alternately layered and filled to increase the adsorption efficiency.
In the present invention, the foreign matter adsorbent 11 filled in the used septic tank 2 has already adsorbed CO2 and foreign matter contained in the drain.

The bottom body 13 has a size sufficient to close the bottom (lower) opening of the hollow cylinder main body 10, and is attached by a fastening means such as a screw. The bottom body 13 is provided with an inlet 12 at a predetermined location (preferably approximately the center in a plan view).
A pipe for supplying compressed gas A is connected to the inlet 12 so that the compressed gas A flows into the hollow cylindrical body 10 .

The lid 15 has a size large enough to close the top (upper) opening, and is attached by a fastening means such as a screw. The lid 15 is provided with a discharge port 14 at a predetermined position (preferably approximately the center in a plan view).
A pipe capable of supplying exhaust gas H, which is a mixture of compressed gas A and CO2 desorbed from the foreign matter adsorbent material 11, is connected to the exhaust port 14, and the exhaust gas H discharged from the exhaust port 14 is recovered at a later stage.

The compressed gas A sent to the used septic tank 2 may be generated by a compressor 20 that compresses the atmosphere, or a cylinder filled with the compressed gas A may be provided as a gas supply source, but there is no particular limitation on the gas itself to be sent. For example, compressed air generated by compressing the atmosphere may be used as the compressed gas A as is, or a high-concentration nitrogen gas may be generated from the compressed gas A generated by the compressor 20 through a hollow fiber membrane type separation device in order to prevent oxidation of the oil adhering to the foreign matter adsorbent 11, and sent into the used septic tank 2.
Furthermore, there is no particular limitation on the compressor 20 used to generate the compressed gas A, and any compressor using conventionally known technology may be used.

Incidentally, when using exhaust gas H in a plant growing method 5 described below, not only CO2 but also a moderate amount of O2 is required for plant growth. Also, when performing human work in the planting space 31, O2 is also required for people to breathe. Therefore, it is preferable that O2 is contained in exhaust gas H, which is a mixture of compressed gas A and CO2, and therefore it is preferable that compressed gas A is compressed air.
Generally, the atmosphere contains 78.1% nitrogen, 20.1% O2, 0.9% Ar, 0.04% CO2, and the remainder is other trace components, but it is known that the exhaust gas H discharged from the outlet 14 via the used septic tank 2 has a CO2 concentration two to three times higher than that at the time of inflow. In other words, the exhaust gas H discharged from the used septic tank 2 contains a large amount of CO2.

The exhaust gas H is a gas mixture of compressed gas A and CO2, and is discharged from the exhaust outlet 14 of the used septic tank 2.
The exhaust gas H is a mixture of the compressed gas A and CO2 after the CO2 adsorbed in the foreign matter adsorbent 11 is desorbed by the action of the compressed gas A flowing in from the inlet 12, and rises inside the hollow cylinder body 10 and is discharged from the exhaust port 14. The exhaust gas H is then sent to the subsequent stage via the exhaust piping.
There are no particular limitations on the method of recovering the exhaust gas H. For example, as shown in FIG. 1, the exhaust gas H may be stored and recovered as a gas with a high CO2 concentration in the exhaust gas tank 30, or, although not shown, the exhaust gas may be separated into a high-concentration nitrogen gas and a gas containing CO2 through a hollow fiber membrane type separation device provided at a predetermined location in the exhaust piping, and each of the gases may be recovered in a tank or the like.

In addition to being sent directly to the downstream stage, the exhaust gas H discharged from the used septic tank 2 can also be temporarily stored in a storage facility such as an exhaust gas tank 30 as shown in the figure, and then sent to the downstream facility according to the required amount. By adopting such a configuration, the exhaust gas H sent out is added to the already stored exhaust gas H, making it possible to mitigate sudden increases and decreases in the CO2 concentration in the entire stored exhaust gas H, which contributes to stabilizing the CO2 concentration. In addition, although not shown, by providing a CO2 concentration meter in the exhaust gas tank 30, it is possible to grasp the CO2 concentration of the exhaust gas H that can be sent to the downstream stage, and it becomes easy to calculate the supply amount of exhaust gas H for the required CO2 concentration in the downstream facility.

As shown in the figure, a planting space 31 can be considered as a facility that can utilize the exhaust gas H discharged from the used septic tank 2, and the plant cultivation method 5 of the present invention is constituted by supplying the exhaust gas H to the planting space 31.
The planting space 31 is generally a sealable space facility used for growing plants, such as a vinyl house, a greenhouse, or a plant factory installed inside a building, and the planting space 31 is filled with exhaust gas H. Air can be supplied to the planting space 31 by temporarily storing the exhaust gas in a storage facility such as an exhaust gas tank 30 as shown in the figure and then supplying the air thereto, or by directly supplying the air from the used septic tank 2.
There are no particular limitations on the plants cultivated in the planting space 31, and the plants are appropriately selected taking into consideration the planting area available for the planting space 31 and the cultivation method (for example, greenhouse cultivation or hydroponic cultivation), etc.
Light, moisture, and CO2 are used for photosynthesis during plant growth, and if the ambient CO2 concentration is high during photosynthesis, the photosynthesis rate increases, which has the effect of promoting plant growth. Therefore, by supplying and filling the planting space 31 with exhaust gas and maintaining a high CO2 concentration, it is possible to promote the growth of plants cultivated in the planting space 31. In this case, although not shown in the figure, a control unit is preferably provided near the planting space 31 to automatically calculate the amount of exhaust gas H required to reach the target CO2 concentration in the planting space 31 by automatically or manually obtaining values from a CO2 concentration meter provided in the planting space 31 and a CO2 concentration meter provided in the exhaust gas tank 30, and automatically opening and closing the valve 32 that allows the exhaust gas H to flow into the planting space 31.

The main operations and effects of the CO2 separation method 1 and plant cultivation method 5 configured as above will be described with reference to FIG.
First, the compressed gas A generated by the compressor 20 is sent toward the used purification device 2 and flows into the hollow cylinder body 10 from the inlet 12. The compressed gas A that flows into the hollow cylinder body 10 rises while desorbing the CO2 adsorbed on the foreign matter adsorbent 11 filled in the hollow cylinder body 10, and is discharged from the outlet 14 as exhaust gas H mixed with the desorbed CO2. The exhaust gas H discharged from the outlet 14 is then stored in the exhaust gas tank 30 via piping to stabilize the CO2 concentration, and a required amount is then sent to the planting space 31, thereby increasing the CO2 concentration in the planting space 31.

The basic configuration and operation of the CO2 separation method 1 and plant cultivation method 5 according to the present invention have been described above, but the present invention is not limited to the configuration shown in the above embodiment and drawings. For example, compressed gas A, which has become high-concentration nitrogen gas through a hollow fiber membrane separator, is introduced into a used purification device 2, and exhaust gas H, which is a mixture of CO2 desorbed from the foreign matter adsorbent 11 and compressed gas A, is discharged from the exhaust port 14. The high-concentration nitrogen gas and compressed gas A are separated through another hollow fiber membrane separator, and the separated high-concentration nitrogen gas and compressed gas A are merged and then introduced back into the used purification tank 2. The gas separated by the separator and rich in CO2 is mixed with the atmosphere and introduced into the planting space 31 as a gas for adjusting the CO2 concentration.

As described above, the CO2 separation method and plant cultivation method of the present invention can be used to increase the CO2 concentration in the planting space 31 after the CO2 adsorbed in the foreign matter adsorbent 11 is desorbed by sending compressed gas A to the used septic tank 2, and the compressed gas A and the desorbed CO2 are mixed to form compressed exhaust gas H, which is then discharged to the subsequent stage. This contributes to reducing the amount of CO2 released to the outside when the foreign matter adsorbent 11 is removed and incinerated, and to efficiently create the CO2 needed for plant cultivation.

The present invention can be adopted as a CO2 separation method that reduces the amount of CO2 released when replacing or disposing of adsorbents in any field that uses septic tanks that adsorb CO2. The exhaust gas containing the CO2 desorbed from the adsorbent can also be sent to a planting space to increase the CO2 concentration and promote plant growth, playing a part in reducing atmospheric CO2, which is said to be a cause of global warming. Therefore, it is believed that the "CO2 separation method and plant cultivation method" of the present invention has great industrial applicability.

Reference Signs List 1 CO2 separation method 2 Used septic tank 5 Plant cultivation method 10 Hollow cylinder body 11 Foreign matter adsorbent 12 Inlet 13 Bottom body 14 Exhaust port 15 Lid body 20 Compressor 30 Exhaust gas tank 31 Planting space 32 Valve A Compressed gas H Exhaust gas

Claims (4)

A septic tank comprising: a hollow cylindrical body having a hollow portion, the hollow portion being filled with a foreign matter adsorbent; a bottom body having an inlet at a predetermined location and capable of closing the lower open end of the hollow cylindrical body via a fastening means; and a cover body having an outlet at a predetermined location and capable of closing the upper open end of the hollow cylindrical body via a fastening means, the septic tank being disposed in a compressed air pressure circuit for the purpose of cleaning drain generated in the circuit ,
A CO2 separation method characterized by sending compressed gas through an inlet to a used septic tank that remains filled with foreign matter adsorbent material to which CO2 and foreign matter contained in the drain has been adsorbed , causing the inflowing compressed gas to desorb the CO2 from the foreign matter adsorbent material, and discharging and recovering the exhaust gas containing a mixture of compressed gas and CO2 through an outlet, thereby separating and recovering the CO2 adsorbed to the foreign matter adsorbent material.
The method for separating CO2 according to claim 1, characterized in that the compressed gas is compressed air. A method for utilizing exhaust gas captured by the CO2 separation method described in claim 2, comprising the step of supplying the exhaust gas to a planting space to promote plant growth. 4. The plant growing method according to claim 3, wherein the planting space is any one of a vinyl house, a greenhouse, and a plant factory.