N2O treatment system

Abstract

The present invention provides an N2O treatment system (100) comprising: a cultivation facility (1) forming a cultivation space (1a) for cultivating crops in nitrogen-containing soil (10); a flow path forming portion (12) extending substantially parallel to the surface of the soil (10) in the cultivation space (1a), having an opening (12a) facing the soil (10) and forming a flow path (12b) for N2O discharged from the soil (10) to pass through the opening (12a); and a treatment device (2) connected to the flow path forming portion (12) for sucking in and treating the N2O discharged through the flow path (12b).

Description

Technical Field

[0001] The present invention relates to a nitrous oxide (N2O) treatment system for treating N2O released from soil of a cultivation facility. Background Art

[0002] Conventionally, there are known devices for treating various greenhouse gases (see, for example, Patent Document 1). The device described in Patent Document 1 collects carbon dioxide exhausted from a cogeneration device and supplies it to a plant cultivation facility.

[0003] However, when crops are grown on soil fertilized with nitrogen fertilizer, N2O is generated from the soil and released into the atmosphere. N2O has an extremely high greenhouse effect, approximately 300 times that of the representative greenhouse gas, carbon dioxide, and is also a stratospheric ozone depleting substance. Therefore, to mitigate global warming, it is essential to effectively manage N2O emitted from the soil of cultivation facilities. However, Patent Document 1 does not make any suggestions regarding this.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2016-052633 (JP 2016-052633 A). Summary of the Invention

[0007] A N2O treatment system according to one technical solution of the present invention comprises: a cultivation facility forming a cultivation space for cultivating crops in nitrogen-containing soil; a flow path forming portion extending approximately parallel to the surface of the soil in the cultivation space, having an opening facing the soil and forming a flow path for N2O released from the soil through the opening; and a treatment device connected to the flow path forming portion for sucking in and treating the N2O discharged through the flow path. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The objects, features and advantages of the present invention will be further clarified through the following description of the embodiments in conjunction with the accompanying drawings.

[0009] Figure 1 This is a conceptual diagram schematically showing an example of the overall configuration of an N2O treatment system according to an embodiment of the present invention.

[0010] Figure 2 It is a schematic diagram showing the control Figure 1 A block diagram of an example of the peripheral configuration of a controller of a fuel supply unit. DETAILED DESCRIPTION

[0011] The following reference Figure 1 and Figure 2An embodiment of the present invention will be described. The N2O treatment system of an embodiment of the present invention recovers and processes N2O released from the soil within a cultivation facility. When cultivating crops, nitrogen fertilizer is applied to the soil to promote the growth of the crops. In such fertilized soil, the nitrogen contained in the soil is decomposed by microorganisms to produce N2O, which is released from the soil surface into the atmosphere. N2O has an extremely high greenhouse effect, approximately 300 times that of the representative greenhouse gas carbon dioxide, and is also a substance that depletes the stratospheric ozone layer. Therefore, from the perspective of preventing global warming, it is not appropriate to discharge N2O directly into the atmosphere through ventilation within the cultivation facility.

[0012] At high temperatures, N₂O decomposes into nitrogen and oxygen as shown in the following formula (i), becoming a combustion-supporting gas that promotes combustion reactions. Therefore, in this embodiment, an N₂O treatment system is constructed as follows to minimize environmental impact by recovering N₂O emitted from the soil within a cultivation facility and using it for combustion reactions.

[0013] N2O→N2+O (i)

[0014] Figure 1 This is a conceptual diagram schematically showing an example of the overall configuration of the N2O treatment system 100 according to an embodiment of the present invention. Figure 1 As shown, the N2O treatment system 100 mainly includes a cultivation facility 1 and a treatment device 2. The cultivation facility 1 forms a cultivation space 1a for cultivating crops in fertilized soil 10, and the treatment device 2 treats N2O contained in the internal gas of the cultivation facility 1. The system also includes a generator 4 and a power conditioner 5 connected to the generator 4 and a commercial power system (not shown) via a power supply circuit.

[0015] Processing device 2 is comprised of a reciprocating power machine (reciprocating engine), such as a gas engine. Fuel is supplied to processing device 2 from a fuel supply unit 3, which includes a fuel tank and a fuel pump. Thermal energy generated by combustion in processing device 2 is converted into rotational motion and output to generator 4, which is connected via output shaft 2a. This causes generator 4 to rotate, generating electricity.

[0016] The power conditioner 5, which includes an inverter and other components, converts the power generated by the generator 4 into AC power of an appropriate frequency and supplies it to various components of the N2O treatment system 100. When there is excess power generated by the generator 4, the power conditioner 5 supplies the generated power to the commercial power system (selling power). When there is a shortage, the power conditioner 5 supplies power from the commercial power system to various components of the N2O treatment system 100 (buying power).

[0017] The cultivation facility 1 is configured as, for example, a plastic greenhouse in which fertilized soil 10 for cultivating crops is covered with a frame such as pipes and a plastic film to form a cultivation space 1a. The cultivation facility 1 can also be configured as an indoor facility in which fertilized soil 10 is laid on the ground, or as a facility in which flower boxes containing fertilized soil 10 are arranged.

[0018] A pipe 11 is connected to the cultivation facility 1, connecting the cultivation space 1a with the outside space. External air enters the cultivation space 1a through the pipe 11. A heat exchanger 6 and an air intake fan 7 are provided in the pipe 11. The air entering from the outside space via the air intake fan 7 and heated by the heat exchanger 6 enters the cultivation space 1a through the pipe 11, thereby maintaining the cultivation space 1a at a temperature suitable for crop growth. The air intake fan 7 is supplied with electricity generated by the generator 4.

[0019] An air intake pipe 12 connected to the air intake side of the processing device 2 is provided in the cultivation space 1a of the cultivation facility 1, extending approximately parallel to the surface 10a of the fertilized soil 10. More specifically, the air intake pipe 12 branches into a network or multiple pipes, for example, to cover the entire ground surface covered with the fertilized soil 10, avoiding the crops, and horizontally covers the entire cultivation space 1a.

[0020] The air intake pipe 12 is provided with a plurality of openings 12a facing the fertilized soil 10, forming a flow path 12b for the N2O released from the fertilized soil 10 to pass through the openings 12a. The air intake pipe 12 is arranged near the surface 10a of the fertilized soil 10, maintaining a distance (e.g., several centimeters) from the surface 10a of the fertilized soil 10 to prevent foreign matter such as soil from blocking the openings 12a.

[0021] As the processing device 2 operates, the internal gas of the cultivation space 1a is drawn into the processing device 2 via the air intake pipe 12. In particular, since N2O released from the fertilized soil 10 is heavier than air (nitrogen, oxygen, etc.), it effectively enters the flow path 12b of the air intake pipe 12 through the opening 12a near the surface 10a of the fertilized soil 10 and is drawn into the processing device 2 via the flow path 12b. An intake air concentration sensor 20 is provided in the air intake pipe 12 to detect the N2O concentration Cin of the internal gas of the cultivation facility 1 drawn into the processing device 2.

[0022] The processing device 2 mixes the internal gas of the cultivation facility 1, which is drawn in through the air intake pipe 12, with the fuel supplied by the fuel supply unit 3, and combusts the mixed gas (combustion process). During the combustion process in the processing device 2, N2O decomposes into nitrogen and oxygen at the high temperature generated by the combustion reaction. The oxygen generated by the decomposition reaction promotes the combustion reaction in the processing device 2. The exhaust gas discharged from the processing device 2 is discharged through the exhaust pipe 21.

[0023] Exhaust pipe 21 includes pipe 21a having one end connected to the exhaust side of treatment device 2, pipe 21b having one end open to the water in water storage tank 8, and pipe 21c having one end connected to pipe 21b. The other ends of pipes 21a to 21c are respectively connected to three-way valves 22. Heat exchanger 6 is provided on pipe 21c.

[0024] When three-way valve 22 is switched to connect pipes 21a and 21b, exhaust gas from treatment device 2 flows to pipe 21b without passing through heat exchanger 6. On the other hand, when three-way valve 22 is switched to connect pipes 21a and 21c, exhaust gas from treatment device 2 flows to pipe 21b through heat exchanger 6. In this case, outside air entering pipe 11 via intake fan 7 is heated in heat exchanger 6 by the high-temperature exhaust gas from treatment device 2. For example, by switching three-way valve 22 based on the outside air temperature, heating or non-heating the outside air entering cultivation space 1a of cultivation facility 1 via pipe 11 can be switched, thereby maintaining cultivation space 1a within a temperature range suitable for crop growth.

[0025] When exhaust gas from treatment device 2 is introduced into the water in water tank 8 via exhaust pipe 21 (pipe 21b), the carbon dioxide in the exhaust gas dissolves in the water, and the exhaust gas, with a reduced carbon dioxide concentration, accumulates in upper space 8a of water tank 8. Pipe 23 is connected to water tank 8, connecting upper space 8a to the outside world. Exhaust gas in upper space 8a is guided through pipe 23 to the outside world and discharged into the atmosphere. An exhaust gas concentration sensor 24 is installed on pipe 23 to detect the N2O concentration Cex of the exhaust gas discharged into the atmosphere.

[0026] A sprinkler system 13 and lighting 14 are also installed in the cultivation space 1a of the cultivation facility 1. These systems are supplied with electricity generated by the generator 4. The sprinkler system 13 sprays water stored in a water tank 8, which has dissolved carbon dioxide contained in the exhaust gas discharged from the treatment device 2, into the cultivation space 1a. This watering simultaneously increases the carbon dioxide concentration in the cultivation space 1a while watering the crops in the cultivation space 1a. The crops in the cultivation space 1a undergo photosynthesis under the influence of sunlight or light from the lighting 14, which absorbs carbon dioxide from the cultivation space 1a and contributes to the growth of the crops.

[0027] Figure 2 1 is a block diagram schematically showing an example of the peripheral configuration of the controller 50 that controls the fuel supply unit 3. Figure 2 As shown, the controller 50 includes a computer having a computing unit 51 such as a CPU (Central Processing Unit), a storage unit 52 such as a ROM (Read Only Memory) and a RAM (Random Access Memory), and other peripheral circuits. The intake air concentration sensor 20, the exhaust gas concentration sensor 24, and the fuel supply unit 3 are connected to the controller 50.

[0028] The controller 50 controls the fuel supply unit 3 based on the N2O concentration Cin detected by the intake air concentration sensor 20 and the N2O concentration Cex detected by the exhaust gas concentration sensor 24. More specifically, the controller 50 calculates the fuel supply amount to the treatment device 2 according to, for example, a predetermined characteristic, and controls the fuel supply unit 3 based on the calculation result so that the N2O is completely decomposed through combustion in the treatment device 2. Specifically, the controller 50 calculates the amount of oxygen generated by the decomposition of the N2O based on the difference between the N2O concentration Cin detected by the intake air concentration sensor 20 and the N2O concentration Cex detected by the exhaust gas concentration sensor 24. The controller 50 then calculates the fuel supply amount according to the predetermined characteristic, taking this oxygen amount into account.

[0029] The present embodiment can achieve the following effects.

[0030] (1) The N2O treatment system 100 comprises: a cultivation facility 1, which forms a cultivation space 1a for cultivating crops in nitrogen-containing fertilized soil 10; an air intake pipe 12, which extends substantially parallel to the surface 10a of the fertilized soil 10 in the cultivation space 1a, is provided with an opening 12a facing the fertilized soil 10, and forms a flow path 12b for N2O released from the fertilized soil 10 to pass through the opening 12a; and a treatment device 2, which is connected to the air intake pipe 12 and sucks in and treats the N2O ( Figure 1 By providing openings 12a facing the fertilized soil 10 of the cultivation facility 1, N2O, which is heavier than air and released from the fertilized soil 10, can be effectively recovered and processed. Furthermore, by recovering N2O within the cultivation space 1a of the cultivation facility 1, such as a plastic greenhouse, diffusion of N2O into the external space can be suppressed, allowing for efficient recovery.

[0031] (2) The N2O treatment system 100 further comprises: a water storage tank 8; an exhaust pipe 21, one end of which is connected to the exhaust side of the treatment device 2 and the other end is open to the water in the water storage tank 8; and a sprinkler 13, which sprays the water stored in the water storage tank 8 into the cultivation space 1a ( Figure 1 ). As a result, the carbon dioxide generated by the treatment of N2O can be effectively recovered and used for the growth of crops.

[0032] (3) The N2O treatment system 100 further comprises: a pipe 11 connecting the cultivation space 1a and the external space; an air intake fan 7 provided on the pipe 11 for allowing external air to enter the cultivation space 1a from the external space; and a heat exchanger 6 provided on the pipe 11 for heating the external air entering via the air intake fan 7 using the exhaust gas discharged from the treatment device 2 ( Figure 1 ). Thus, the cultivation space 1a can be maintained in a temperature range suitable for the growth of crops.

[0033] (4) The N2O treatment system 100 further includes: an intake air concentration sensor 20 for detecting the N2O concentration of the intake air entering the treatment device 2; an exhaust gas concentration sensor 24 for detecting the N2O concentration of the exhaust gas discharged from the treatment device 2; a fuel supply unit 3 for supplying fuel to the treatment device 2; and a controller 50 for controlling the fuel supply unit 3 ( Figure 1 The treatment device 2 mixes N2O drawn in through the flow path 12b with the fuel supplied by the fuel supply unit 3 and performs a combustion process. The controller 50 controls the fuel supply unit 3 based on the N2O concentration detected by the intake air concentration sensor 20 and the N2O concentration detected by the exhaust gas concentration sensor 24. The controller 50 accurately calculates the amount of fuel supplied to the treatment device 2 according to, for example, predetermined characteristics, and appropriately controls the fuel supply unit 3 based on the calculation result so that the N2O is completely decomposed by the combustion process in the treatment device 2.

[0034] (5) The processing device 2 is a reciprocating power machine (reciprocating engine). This allows the N2O in the cultivation facility 1 to be processed and the cultivation facility 1 to be ventilated and illuminated using electricity generated by the heat energy obtained by combustion.

[0035] In the above embodiment, Figure 1 The specific example of the cultivation facility 1 is shown in FIG. 1 , but the cultivation facility may be in any form as long as it forms a cultivation space for cultivating crops in nitrogen-containing soil. Figure 1 The example of the tubular intake pipe 12 is described in the above description, but the flow path forming portion that forms the flow path for the N2O released from the soil to pass through is not limited to this. It can also be a box-shaped member that covers the fertilized soil as a whole, or a member that covers the fertilized soil as a whole by combining these. In the above embodiment, Figure 1 Although a specific example of the sprinkler 13 is shown and described in the above description, the sprinkler can be installed on a wall or the ground in addition to the ceiling surface of the cultivation facility as long as it sprays water stored in a water tank into the cultivation space.

[0036] One or more of the above-described embodiments and modifications may be arbitrarily combined, and modifications may be combined with each other.

[0037] The present invention can effectively treat N2O released from the soil of a cultivation facility.

[0038] The present invention has been described above in conjunction with preferred embodiments. It should be understood by those skilled in the art that various modifications and changes can be made without departing from the scope of the claims set forth below.

Claims

1. A N2O treatment system (100), characterized in that: have: A cultivation facility (1) forming a cultivation space (1a) for cultivating crops in nitrogen-containing soil (10); a flow path forming portion (12) extending substantially parallel to the surface of the soil (10) in the cultivation space (1a), having an opening (12a) facing the soil (10) and forming a flow path (12b) for N2O emitted from the soil (10) to pass through the opening (12a); a processing device (2) connected to the flow path forming portion (12), sucking in the N2O discharged through the flow path (12b), and performing combustion treatment to decompose the N2O into nitrogen and oxygen; Water storage tank (8); an exhaust pipe (21), one end of which is connected to the exhaust side of the treatment device (2) and the other end of which is open to the water in the water storage tank (8); a watering device (13) for spraying the water stored in the water storage tank (8) onto the cultivation space (1a); a pipe (11) connecting the cultivation space (1a) and the external space; an air intake fan (7) provided on the pipe (11) for allowing external air to enter the cultivation space (1a) from the external space; lighting (14), which is provided in the cultivation facility (1) and irradiates light; and a heat exchanger (6) provided in the piping (11) for heating the external air introduced by the air intake fan (7) by utilizing the exhaust gas discharged from the processing device (2); The exhaust gas is introduced into the water in the water storage tank (8) via an exhaust pipe (21), and the exhaust gas not dissolved in the water is discharged to the external space via a pipe provided in the water storage tank (8).

2. The N2O treatment system (100) according to claim 1, characterized in that: Also features: an intake air concentration sensor (20) for detecting the N2O concentration of the intake air entering the processing device (2); an exhaust gas concentration sensor (24) for detecting the N2O concentration of the exhaust gas discharged from the treatment device (2); a fuel supply unit (3) for supplying fuel to the processing device (2); and A control unit (50) controls the fuel supply unit (3). The processing device (2) mixes the N2O sucked in through the flow path (12b) and the fuel supplied by the fuel supply unit (3) and performs combustion processing. The control unit (50) controls the fuel supply unit (3) based on the N2O concentration detected by the intake air concentration sensor (20) and the N2O concentration detected by the exhaust gas concentration sensor (24).

3. The N2O treatment system (100) according to claim 1 or 2, characterized in that: The processing device (2) is a reciprocating power machine.

4. The N2O treatment system (100) according to claim 1 or 2, characterized in that: The flow path forming portion (12) is an air intake pipe configured in a tubular shape and is arranged so as to entirely cover the soil (10).

5. The N2O treatment system (100) according to claim 1 or 2, characterized in that: The flow path forming portion (12) is configured in a box shape and is arranged so as to entirely cover the soil (10).

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