NL2021514B1

NL2021514B1 - Carbon dioxide application device

Info

Publication number: NL2021514B1
Application number: NL2021514A
Authority: NL
Inventors: Saito Takashi; Yumidate Masaki
Original assignee: Futaba Ind Co Ltd
Priority date: 2017-08-31
Filing date: 2018-08-29
Publication date: 2019-09-13
Also published as: KR20190024789A; JP2019041638A; CN109417957A; KR102164859B1; JP6718419B2; NL2021514A; CN109417957B

Abstract

A carbon dioxide application device includes an absorption tank, a supplycontroller, and a concentration detector. The supply-controller supplies carbon 5 dioxide absorbed by an absorber in the absorption tank to an inside of the agriculture greenhouse. The concentration detector measures or estimates a concentration of carbon dioxide that is supplied from the absorption tank to the inside ofthe agriculture greenhouse. The supply-controller supplies carbon dioxide from the auxiliary application device to the inside of the agriculture greenhouse if the concentration of 10 carbon dioxide, which is measured or estimated by the concentration detector, falls below a threshold value when carbon dioxide is supplied from the absorption tank.

Description

BACKGROUND [0001] The present disclosure relates to a carbon dioxide application device.

[0002] A carbon dioxide application device for application of carbon dioxide inside agriculture greenhouses to improve the yield and quality of garden plants is publicly known. Meanwhile, agriculture greenhouses are provided with heaters to prevent a decline of temperature in the night-time. Those heaters combust heavy oil, heating oil, or the like to generate heated air and supply the heated air to the agriculture greenhouses.

[0003] As disclosed in JP2015-142531, a carbon dioxide application device that reserves carbon dioxide, included in combustion exhaust gases generated from a heater in the night-time, by an absorber and supplies the reserved carbon dioxide to the inside of an agriculture greenhouse is being developed.

SUMMARY [0004] However, in an occasion where, for example, a rate of operation of the heater in the night-time is low, the absorber of the carbon dioxide application device cannot reserve sufficient amount of carbon dioxide. This causes a difficulty in sufficiently supplying carbon dioxide to the inside of the agriculture greenhouse in the daytime.

[0005] Desirably, one aspect of the present disclosure is to appropriately supply carbon dioxide to an inside of an agriculture greenhouse.

[0006] One mode of the present disclosure is a carbon dioxide application device that serves as a main application device configured to supply carbon dioxide included in combustion exhaust gases to an inside of an agriculture greenhouse. The carbon dioxide application device comprises an absorption tank, flow-down equipment, a supply-controller, and a concentration detector. The absorption tank comprises therein an absorber configured to absorb carbon dioxide in the combustion exhaust gases. The flow-down equipment

-2is located in a carbon dioxide supply path and configured to cause gases in the carbon dioxide supply path to flow downstream. The supply-controller is configured to supply carbon dioxide, absorbed into the absorber in the absorption tank, to the inside of the agriculture greenhouse via the carbon dioxide supply path and by the flow-down equipment. The concentration detector is configured to measure or estimate concentration of carbon dioxide supplied from the absorption tank to the inside of the agriculture greenhouse. The supply-controller is configured to supply carbon dioxide from an auxiliary application device to the inside of the agriculture greenhouse via the carbon dioxide supply path and by the flow-down equipment if the concentration of carbon dioxide measured or estimated by the concentration detector is below a preset threshold value A when supplying carbon dioxide from the absorption tank to the inside of the agriculture greenhouse.

[0007] According to the aforementioned configuration, when sufficient amount of carbon dioxide cannot be supplied from the absorption tank to the agriculture greenhouse because of a decrease in the amount of reserved carbon dioxide left in the absorption tank, the auxiliary application device supplies carbon dioxide to the agriculture greenhouse. Thus, in an occasion where the absorption tank does not reserve sufficient amount of carbon dioxide, the agriculture greenhouse can be still sufficiently supplied with carbon dioxide.

[0008] Accordingly, carbon dioxide can be appropriately supplied to the inside of the agriculture greenhouse.

Additionally, the concentration detector may further be configured to measure or estimate a concentration of carbon dioxide supplied from the auxiliary application device to the inside of the agriculture greenhouse. The supply-controller may also be configured to stop the supply of carbon dioxide from the auxiliary application device if the concentration of supplied carbon dioxide, which is measured or estimated by the concentration detector, exceeds a preset threshold value B when carbon dioxide is being supplied from the auxiliary application device to the inside of the agriculture

-3greenhouse. The threshold value B is determined separately from the aforementioned threshold value A.

[0009] According to such a configuration, if the concentration of carbon dioxide inside the agriculture greenhouse reaches an appropriate concentration due to the supply of carbon dioxide from the auxiliary application device, the supply of carbon dioxide from the auxiliary application device is stopped. This helps reduce excess operation of the auxiliary application device, and helps keep the appropriate concentration of carbon dioxide inside the agriculture greenhouse.

The concentration detector may measure or estimate the concentration of carbon dioxide supplied to the inside of the agriculture greenhouse based on the concentration of carbon dioxide in the carbon dioxide supply path.

The concentration detector may also measure or estimate the concentration of carbon dioxide supplied to the inside of the agriculture greenhouse based on the concentration of carbon dioxide inside the agriculture greenhouse.

According to such a configuration, the concentration of carbon dioxide supplied to the inside of the agriculture greenhouse can be preferably measured or estimated.

In addition, the concentration detector may further be configured to measure or estimate the concentration of carbon dioxide inside the agriculture greenhouse. The supply-controller may also be configured to stop the supply of carbon dioxide when carbon dioxide is being supplied to the inside of the agriculture greenhouse if the concentration of carbon dioxide inside the agriculture greenhouse, which is measured or estimated by the concentration detector, exceeds a threshold value C that is determined separately from the aforementioned threshold value A.

According to such a configuration, appropriate amount of carbon dioxide can be supplied to the inside of the agriculture greenhouse.

-4In addition, the supply-controller may be configured to supply carbon dioxide from the absorption tank to the inside of the agriculture greenhouse through the carbon dioxide supply path and by the flow-down equipment if the concentration of carbon dioxide inside the agriculture greenhouse, which is measured or estimated by the concentration detector, falls below the threshold value C after the supply of carbon dioxide to the inside of the agriculture greenhouse is stopped.

[0010] Furthermore, the auxiliary application device may be configured as a device to heat the inside of the agriculture greenhouse by fuel combustion at the same time as generating carbon dioxide.

According to such a configuration, efficient use of energy can be achieved.

The auxiliary application device may also be configured as a device to generate carbon dioxide by fuel combustion. The supply-controller may also be configured to cause combustion exhaust gases generated by the fuel combustion in the auxiliary application device to flow downstream towards the absorption tank through the carbon dioxide supply path and by the flowdown equipment, and to cause carbon dioxide included in the combustion exhaust gases to be absorbed by the absorber.

According to such a configuration, carbon dioxide included in the combustion exhaust gases generated in the auxiliary application device can be efficiently utilized.

[0011] The auxiliary application device may also be configured as a cylinder for reserving carbon dioxide. The supply-controller may also be configured to supply carbon dioxide, discharged from the auxiliary application device and diluted with air, to the inside of the agriculture greenhouse.

[0012] Such a configuration enables reduction of local supply of carbon dioxide in the inside of the agriculture greenhouse and also enables supply of carbon

-5dioxide to the inside of the agriculture greenhouse at an appropriate concentration.

BRIEF DESCRIPTION OF THE DRAWINGS [0013] An example embodiment of the present disclosure will be described hereinafter with reference to the accompanying drawings, in which:

FIG. 1 is a block diagram schematically showing a configuration of a carbon dioxide application device according to an embodiment;

FIG. 2 is a flowchart showing a carbon dioxide supply process;

FIG. 3 is a graph showing a change in concentration of carbon dioxide in an inside of an agriculture greenhouse.

FIG. 4 is a graph showing a change in concentration of carbon dioxide in a flow path of the carbon dioxide application device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0014] The present disclosure is not limited to the embodiments explained hereinafter and may be modified in various modes within the technical scope of the present disclosure.

[1. Configuration]

FIG. 1 shows a carbon dioxide application device 1 configured as a main application device for supplying carbon dioxide included in combustion exhaust gases to an inside of an agriculture greenhouse 100. The carbon dioxide application device 1 is arranged inside or outside the agriculture greenhouse 100. The carbon dioxide application device 1 comprises a combustor 2, a first liquid-reserving-tank 3, a second liquid-reserving-tank 4, a blower 5, an absorption tank 6, a controller 7, a purifier 8, and an auxiliary application device 9.

[0015] The carbon dioxide application device 1 also comprises a flow path that is configured to cause the combustion exhaust gases to flow downstream and to cause carbon dioxide to flow downstream towards the inside of the

-6agriculture greenhouse 100. Specifically, the carbon dioxide application device 1 comprises an exhaust gas flow path 10, a first intake flow path 11, a cooling air flow path 12, a second intake flow path 13, an applied air flow path 14, an interior flow path 15, an auxiliary flow path 16, an exterior flow path 17, and a first tank flow path 18 to a third tank flow path 20. In addition, the carbon dioxide application device 1 comprises open-close valves 12A, 14A, 15A, 15B, 16A, 17A, and 17B configured to open and close the flow paths.

[0016] <Combustor>

The combustor 2 combusts fuel such as heavy oil and heating oil mainly in the night-time and heats air inside the agriculture greenhouse 100. The combustion exhaust gases are discharged through the exhaust gas flow path 10, which serves as a chimney.

[0017] <First and Second Liquid-reserving-tanks>

A first liquid-reserving-tank 3 and a second liquid-reserving-tank 4 reserve liquid inside and cool and purify a part of the combustion exhaust gases generated from the combustor 2 by using the liquid.

[0018] The combustion exhaust gases generated in the combustor 2 flows into the first liquid-reserving-tank 3 via the first intake flow path 11. The combustion exhaust gases that passed the first liquid-reserving-tank 3 then flows into the second liquid-reserving-tank 4 via the second intake flow path

13. The combustion exhaust gases that passed the second liquid-reservingtank 4 then flows into the interior flow path 15.

[001 9] Each of the first and second liquid-reserving-tanks 3 and 4 is configured such that the combustion exhaust gases that flowed into the tank pass through the liquid inside the tank. In the first and second liquid-reserving-tanks 3 and 4, the combustion exhaust gases are cooled due to heat exchange with the liquid, and simultaneously, a part of components included in the combustion exhaust gases is removed by a compound included in the liquid. In other words, the carbon dioxide application device 1 cools and purifies the

-7combustion exhaust gases in two steps by using the first and second liquidreserving-tanks 3 and 4.

[0020] Preferably, the liquid reserved in the first and second liquid-reservingtanks 3 and 4 are capable of removing harmful substances, such as sulfides and/or nitrides, included in the combustion exhaust gases. For example, an aqueous solution of a compound that reacts with sulfides and/or nitrides is preferable.

[0021] In addition, the first liquid-reserving-tank 3 is coupled to the cooling air flow path 12 that cools the reserved liquid. The cooling air flow path 12 cools the liquid by supplying cooling air into the liquid. The cooling air flow path 12 comprises the open-close valve 12A. The open-close valve 12A is opened when cooling air is supplied into the liquid, otherwise the openclose valve 12A is closed.

[0022] <Blower>

The blower 5 is a flow-down equipment arranged in the interior flow path 15 and causes the gases in the interior flow path 15 to flow downstream. The blower 5 supplies the combustion exhaust gases to the absorption tank 6 through the flow paths and supplies carbon dioxide to the inside of the agriculture greenhouse 100 from the absorption tank 6 or from the auxiliary application device 9. One end of the interior flow path 15 is situated inside the agriculture greenhouse 100. The exterior flow path 17 branches from the interior flow path 15, and one end of the exterior flow path 17 is situated outside the agriculture greenhouse 100.

[0023] In response to operation of the blower 5, gases in the interior flow path 15, such as the combustion exhaust gases, are transferred towards the agriculture greenhouse 100 and the exterior flow path 17 by pressure. Hereinafter, the direction in the flow paths towards which the gases are transferred by pressure by the blower 5 is downstream; the direction opposite the downstream is upstream.

[0024] <Absorption Tank>

-8The absorption tank 6 comprises therein an absorber that absorbs carbon dioxide in the combustion exhaust gases. The absorber may be, for example, a porous material such as an activated carbon or zeolite. The absorption tank 6 is coupled to a first tank-flow path 18 that branches from the exterior flow path 17. The absorption tank 6 is also coupled to the purifier 8 via a second tank-flow path 19.

[0025] In an absorption process of carbon dioxide, which will be explained later, carbon dioxide included in the combustion exhaust gases is absorbed by the absorber when the combustion exhaust gases pass through the absorption tank 6. Meanwhile, in a carbon dioxide application process (also referred to as an application process), which will also be explained later, carbon dioxide is desorbed from the absorber in response to the applied air passing inside the absorption tank 6. The desorbed carbon dioxide is then applied to the inside of the agriculture greenhouse 100.

[0026] <Purifier>

The purifier 8 removes harmful substances (for example, sulfur oxide and nitrogen oxide) that adversely affect growth of plants from the combustion exhaust gases. Specifically, the purifier 8 may comprise, for example, a filter that includes granular activated carbon. The purifier 8 may remove the harmful substances included in the combustion exhaust gases that pass through the purifier 8 by causing the granular activated carbon to absorb the harmful substances. The purifier 8 is coupled to a third tank-flow path 20 that branches from the interior flow path 15 at a point downstream of the branching point to the exterior flow path 17.

[0027] <Auxiliary Application Device>

The auxiliary application device 9 supplies carbon dioxide to the inside of the agriculture greenhouse 100 in an occasion where sufficient amount of carbon dioxide cannot be supplied from the absorption tank 6 in the carbon dioxide application process. A conventional device for application of carbon

-9dioxide to an inside of an agriculture greenhouse may be used as the auxiliary application device 9 to configure the carbon dioxide application device 1.

[0028] The auxiliary application device 9 may be configured as a combustor that generates carbon dioxide by combusting fuel, such as heating oil. The auxiliary application device 9 may be configured as, for example, a carbon dioxide cylinder that reserves high-pressure carbon dioxide. Carbon dioxide supplied from the auxiliary application device 9 passes through the auxiliary flow path 16 and enters the interior flow path 15 from upstream of the blower 5.

[0029] <Open-close Valves>

The cooling air flow path 12, the applied air flow path 14, and the auxiliary flow path 16 respectively have the open-close valve 12A, the openclose valve 14A, and the open-close valve 16A. The applied air flow path 14 branches from the interior flow path 15 at a point upstream of the blower 5. One end of the applied air flow path 14 is situated outside the agriculture greenhouse 100.

[0030] The interior flow path 15 comprises a first and second open-close valves 15A and 15B. The first open-close valve 15A is located upstream of the branching point to the third tank-flow path 20 and downstream of the branching point to the exterior flow path 17. The second open-close valve 15B is located downstream of the branching point to the third tank-flow path

20.

[0031 ] The exterior flow path 17 comprises a first and second open-close valves 17A and 17B. The first open-close valve 17A is located upstream of the branching point to the first tank-flow path 18. The second open-close valve 17B is located downstream of the branching point to the first tank-flow path

18.

[0032] <Controller>

The controller 7 is a device configured to control the carbon dioxide application device 1. The controller 7 may comprise a computer, for

- 10example. Specifically, the controller 7 controls operation and cessation of the blower 5, and open and close of each open-close valve arranged on the flow paths. The controller 7 is also configured to receive input of measurement signals from a flow path concentration censor 15C and a greenhouse concentration censor 100A.

[0033] The flow path concentration censor 15C is configured to measure, in the flow paths, concentration of carbon dioxide supplied from the absorption tank 6. In one example, the flow path concentration censor 15C is located downstream of the second open-close valve 15B in the interior flow path 15. The greenhouse concentration censor 100A is configured to measure concentration of carbon dioxide in the inside of the agriculture greenhouse 100. The greenhouse concentration censor 100A is located inside the agriculture greenhouse 100.

[0034] [2. Process]

The carbon dioxide application device 1 executes the absorption process to recover carbon dioxide from the combustion exhaust gases, and the application process to supply carbon dioxide to the inside of the agriculture greenhouse 100.

[0035] <Absorption Process>

The absorption process is conducted by operating the blower 5 during combustion in the combustor 2 mainly in the night-time. The combustion in the combustor 2 may be initiated by the controller 7. In the absorption process, the open-close valve 12A in the cooling air flow path 12, the openclose valve 14A in the applied air flow path 14, the open-close valve 1 6A in the auxiliary flow path 16, the second open-close valve 15B in the interior flow path 15, and the first open-close valve 17A in the exterior flow path 17 are closed, and the first open-close valve 15A in the interior flow path 15, and the second open-close valve 17B in the exterior flow path 17 are opened.

[0036] Consequently, the combustion exhaust gases generated in the combustor pass through the purifier 8 and the absorption tank 6 in this order due to the

- 11 operation of the blower 5 and flow outside the agriculture greenhouse 100. The harmful substances are removed from the combustion exhaust gases when the combustion exhaust gases pass the purifier 8. Carbon dioxide included in the combustion exhaust gases is absorbed by the absorber when the combustion exhaust gases pass the absorption tank 6.

[0037] <Application Process>

The application process is conducted to supply carbon dioxide to the inside of the agriculture greenhouse 100 in the daytime. The application process includes a main mode, a sub-mode, and a stop-mode. In the main mode, carbon dioxide is supplied from the absorption tank 6. In the submode, carbon dioxide is supplied from the auxiliary application device 9. The main mode and the sub-mode are conducted by the operation of the blower 5. In the stop-mode, the blower 5 is stopped and the supply of carbon dioxide to the inside of the agriculture greenhouse 100 is stopped.

[0038] In the main mode, the open-close valve 12A in the cooling air flow path 12, the open-close valve 16A in the auxiliary flow path 16, the first openclose valve 15A in the interior flow path 15, and the second open-close valve 17B in the exterior flow path 17 are closed, and the open-close valve 14A in the applied air flow path 14, the second open-close valve 15B in the interior flow path 15, and the first open-close valve 17A in the exterior flow path 17 are opened.

[0039] Accordingly, in response to the operation of the blower 5, the applied air flows from the applied air flow path 14 and is transferred to the inside of the agriculture greenhouse 100 by pressure. Specifically, the applied air passes through the absorption tank 6 and the purifier 8 in this order and flows to the inside of the agriculture greenhouse 100. When the applied air passes the absorption tank 6, carbon dioxide absorbed by the absorber flows out, and the flown out carbon dioxide enters the inside of the agriculture greenhouse 100 along with the applied air.

- 12[0040] At or before transition to the sub-mode, for example, the controller 7 initiates the combustion in the auxiliary application device 9 in a case where, for example, the auxiliary application device 9 is configured as the combustor. In the sub-mode, the open-close valve 12A in the cooling air flow path 12, the open-close valve 14A in the applied air flow path 14, and the first and second open-close valves 17A and 17B in the exterior flow path 17 are closed; the open-close valve 16A in the auxiliary flow path 16, and the first and second open-close valves 15A and 15B in the interior flow path 15 are opened.

[0041] Accordingly, in response to the operation of the blower 5, carbon dioxide supplied from the auxiliary application device 9 is transferred to the inside of the agriculture greenhouse 100 by pressure. Specifically, the supplied carbon dioxide passes through the auxiliary flow path 16 and the interior flow path 15 in this order and flows into the inside of the agriculture greenhouse 100.

[0042] In a case where the auxiliary application device 9 is configured as the carbon dioxide cylinder, for example, the controller 7 opens the valve of the carbon dioxide cylinder at the transition to the sub-mode. In this case, the open-close valve 12A in the cooling air flow path 12, and the first and second open-close valves 17A and 17B in the exterior flow path 17 are closed; the open-close valve 14A in the applied air flow path 14, the open-close valve 16A in the auxiliary flow path 16, and the first and second open-close valves 15A and 15B in the interior flow path 15 are opened.

[0043] Accordingly, in response to the operation of the blower 5, the applied air that flows from the applied air flow path 14 and carbon dioxide supplied from the auxiliary application device 9 are transferred to the inside of the agriculture greenhouse 100 by pressure. Specifically, the supplied carbon dioxide is diluted with the applied air to an appropriate concentration and flows to the inside of the agriculture greenhouse 100 via the interior flow path 15. This enables reduction of local supply of carbon dioxide in the inside of

- 13 the agriculture greenhouse 100 and also enables supply of carbon dioxide to the inside of the agriculture greenhouse 100 at an appropriate concentration.

[0044] <Carbon Dioxide Supply Process>

In the application process, the controller 7 regularly initiates a carbon dioxide supply process illustrated in FIG. 2, by which the aforementioned modes are processed. In the supply process, a main-mode flag is used. The main-mode flag is set to 0 (zero) when the carbon dioxide application device 1 is reset.

[0045] In S200, a concentration of carbon dioxide in the inside of the agriculture greenhouse 100 (hereinafter referred to as a concentration in the greenhouse) is measured or estimated based on the measurement signal from the greenhouse concentration censor 100A. During the main mode, concentration in the greenhouse can correspond to concentration of carbon dioxide that is supplied from the absorption tank 6 to the inside of the agriculture greenhouse 100. During the sub-mode, the concentration in the greenhouse can correspond to a concentration of carbon dioxide supplied from the auxiliary application device 9 to the inside of the agriculture greenhouse 100. In addition, the concentration in the greenhouse may be measured or estimated based on the measurement signal from the flow path concentration censor 15C instead of the measurement signal from the greenhouse concentration censor 100A. If the concentration in the greenhouse is equal to or less than a first threshold value (500 ppm for example) (S200: Yes), then the process proceeds to S205. If otherwise (S200: No), then the process proceeds to S240.

[0046] In S205, the controller 7 determines whether the main-mode flag is equal to 1. If the determination is positive (S205: Yes), that is, the main-mode flag is equal to 1, then the process proceeds to S220; if the determination is negative (S205: No), then the process proceeds to S210.

[0047] In S210, the main mode is initiated. In other words, supply of carbon dioxide from the absorption tank 6 to the inside of the agriculture greenhouse

- 14100 is initiated. The main-mode flag is set to 1 in the subsequent S215, and then the process ends.

[0048] In S220, the controller 7 determines whether t second (for example, 10 seconds) has passed since the initiation of the main mode. If the determination is positive (S220: Yes), that is, the t seconds has passed, then the process proceeds to S225. If the determination is negative (S220: No), then the process proceeds to S235.

[0049] In S225, the concentration of carbon dioxide in a downstream area of the second open-close valve 15B in the interior flow path 15 (hereinafter referred to as a concentration in the flow path) is measured based on the measurement signal from the flow path concentration censor 15C. A concentration of carbon dioxide supplied from the absorption tank 6 to the inside of the agriculture greenhouse 100 (hereinafter referred to as a supply concentration) is measured or estimated based on the concentration in the flow path. The supply concentration may be measured or estimated based on the measurement signal from the greenhouse concentration censor 100A instead of the measurement signal from the flow path concentration censor 15C. It is then determined whether the measured or estimated supply concentration is less than a preset threshold value. Specifically, if the concentration in the flow path is equal to or less than a second threshold value (for example, 1.0%) (S225: Yes), the process proceeds to S230. If the concentration in the flow path is equal to the second threshold value, the concentration in the greenhouse may be, for example, equal to or less than 300 ppm. Meanwhile, if the concentration in the flow path is greater than the second threshold value (S225: No), the process proceeds to S235.

[0050] The second threshold value is less than the first threshold value. The supply concentration from the absorption tank 6 may be measured or estimated based not on the concentration in the flow path but on the concentration in the greenhouse. However, compared with a time lag to reflect a change in the supply concentration on the concentration in the flow

- 15 path, a time lag to reflect a decrease in the supply concentration on the concentration in the greenhouse is long. To expedite the measurement or estimation of the supply concentration, the supply concentration is measured or estimated based on the concentration in the flow path.

[0051] In S230, the sub-mode is initiated. In other words, supply of carbon dioxide from the auxiliary application device 9 to the inside of the agriculture greenhouse 100 is initiated. The carbon dioxide supply process then ends. In a case where the auxiliary application device 9 is configured as a combustor, the operation of the blower 5 may be initiated after a specified time lag (for example, 30 seconds) after the initiation of combustion in the auxiliary application device 9 at the transition to the sub-mode. Within this time lag, the open-close valve 14A in the applied air flow path 14 may be opened. This helps discharge carbon monoxide, which is generated at the initiation of the combustion in the auxiliary application device 9, to the atmosphere, and reduces an inflow of such carbon monoxide into the agriculture greenhouse 100.

[0052] In S235, the main mode is continued, and then the carbon dioxide supply process ends.

Meanwhile, in S240, to which the controller 7 proceeds when the concentration in the greenhouse is greater than the first threshold value, the stop-mode is initiated. In other words, supply of carbon dioxide from the absorption tank 6 and from the auxiliary application device 9 is stopped. More specifically, the operation of the blower 5 is stopped. In a case where the auxiliary application device 9 is configured as, for example, a combustor, the combustion of the auxiliary application device 9 may be stopped. In a case where the auxiliary application device 9 is configured as, for example, a carbon dioxide cylinder, a valve of the carbon dioxide cylinder is closed. At the same time, all of the open-close valves 12A, 14A, 15A, 15B, 16A, 17A, and 17B in the flow paths may be closed. In the subsequent S245, the mainmode flag is set to 0 (zero), and then the carbon dioxide supply process ends.

- 16[0053] In the application process, the concentration in the greenhouse changes as shown in the graph of FIG. 3 due to the carbon dioxide supply process. More specifically, if the concentration in the greenhouse decreases to the first threshold value or less at a time TO in the stop-mode, during which carbon dioxide is not supplied to the inside of the agriculture greenhouse 100, a positive determination is made in S200 in the carbon dioxide supply process. In the subsequent S205, a value of the main-mode flag is determined.

[0054] When the concentration in the greenhouse is equal to or less than the first threshold value for the first time in the stop-mode, the main-mode flag is set to 0 (zero). Therefore, the main mode is initiated in S210, and carbon dioxide is supplied from the absorption tank 6 to the inside of the agriculture greenhouse 100. In the subsequent S215, the main-mode flag is set to 1.

[0055] If it is determined in S200 that the concentration in the greenhouse is equal to or less than the first threshold value when the main-mode flag is set to 1, the determination in the subsequent S205 is positive. The process then proceeds to S220 and it is determined whether t second has passed after the transition to the main mode. If the determination in S220 is negative, then the main mode is continued, and the main-mode flag is still set to 1. If the determination in S220 is positive, then the process proceeds to S225 and it is determined whether the concentration in the flow path is equal to or less than the second threshold value. If the determination in S225 is negative, then the main mode is continued, and the main-mode flag is still set to 1. If the determination in S225 is positive, the mode is changed from the main mode to the sub-mode, but the main-mode flag is still set to 1.

[0056] If the concentration in the greenhouse exceeds the first threshold value in the stop-mode, the main mode, or the sub-mode, then the stop-mode is initiated in S240. In the subsequent S245, the main-mode flag is set to 0 (zero).

[0057] In FIG. 3, TO, T2, T4, and T6 each represent a timing of an event that the concentration in the greenhouse changes from exceeding the first

-17threshold value to falling to or below the first threshold value. The main mode is initiated at these timings. Conversely, T1, T3, and T5 each represent a timing of an event that the concentration in the greenhouse changes from being equal to or below the first threshold value to exceeding the first threshold value. The stop-mode is initiated at these timings.

[0058] The line denoted with second threshold value in FIG. 3 is a rough indication of the concentration in the greenhouse when the concentration in the flow path is equal to the second threshold value. The line denoted with first threshold value in FIG. 4 is a rough indication of the concentration in the flow path when the concentration in the greenhouse is equal to the first threshold value.

[0059] After S245, suppose that the concentration in the greenhouse decreases during the stop-mode and a positive determination is made in S200 at T6.

And, suppose also that the time reaches T7 after t second has passed after the initiation of the main mode in S210. Under these conditions, the concentration in the flow path falls to or below the second threshold value as shown in FIG. 4 and a positive determination is made in S225. In other words, the amount of carbon dioxide reserved in the absorption tank 6 has decreased and a sufficient amount of carbon dioxide cannot be supplied from the absorption tank 6. At this time, S230 of the carbon dioxide supply process is executed and the mode is changed to the sub-mode. In other words, carbon dioxide is supplied to the inside of the agriculture greenhouse 100 from the auxiliary application device 9. Then, if it is determined in S200 that the concentration in the greenhouse increases to exceed the first threshold value at T8, S240 of the carbon dioxide supply process is executed and the mode is changed to the stop-mode.

[0060] In the case where the auxiliary application device 9 is configured as a combustor, the inside of the agriculture greenhouse 100 may be heated by the auxiliary application device 9. This enables effective use of energy. Additionally in this case, the carbon dioxide application device 1 may recover

-18carbon dioxide generated in the auxiliary application device 9. Specifically, the controller 7 may close the open-close valve 12A in the cooling air flow path 12, the open-close valve 14A in the applied air flow path 14, the second open-close valve 15B in the interior flow path 15, and the first open-close valve 17A in the exterior flow path 17 and may open the open-close valve 16A in the auxiliary flow path 16, the first open-close valve 15A in the interior flow path 15, and the second open-close valve 17B in the exterior flow path

17. Due to this configuration, carbon dioxide supplied from the auxiliary application device 9 is transferred to the purifier 8 and the absorption tank 6 in this order by pressure in response to the operation of the blower 5. This causes carbon dioxide to be absorbed by the absorber in the absorption tank 6.

[0061] It may also be configured such that carbon dioxide is supplied from the auxiliary application device 9 to the inside of the agriculture greenhouse 100 as the supplied carbon dioxide is recovered at the same time. More specifically, the controller 7 may close the open-close valve 12A in the cooling air flow path 12, the open-close valve 14A in the applied air flow path 14, the first open-close valve 1 5A in the interior flow path 15, and the second open-close valve 17B in the exterior flow path 17 and may open the openclose valve 16A in the auxiliary flow path 16, the second open-close valve 15B in the interior flow path 15, and the first open-close valve 17A in the exterior flow path 17.

[0062] According to this configuration, in response to the operation of the blower 5, carbon dioxide supplied from the auxiliary application device 9 passes the absorption tank 6 and the purifier 8 in this order and flows into the inside of the agriculture greenhouse 100. This enables the supplied carbon dioxide to be absorbed by the absorber in the absorption tank 6. In a case where the amount of carbon dioxide absorbed by the absorber reaches a maximum absorbable amount, carbon dioxide passes through the absorption tank 6 and flows into the inside of the agriculture greenhouse 100.

- 19Accordingly, carbon dioxide can be supplied from the auxiliary application device 9 to the inside of the agriculture greenhouse 100 as the supplied carbon dioxide is recovered at the same time.

[0063] [3. Effects] (1) According to the aforementioned embodiment, in a case where the amount of carbon dioxide reserved in the absorption tank 6 has decreased and a sufficient amount of carbon dioxide cannot be supplied from the absorption tank 6 to the inside of the agriculture greenhouse 100, the auxiliary application device 9 supplies carbon dioxide to the inside of the agriculture greenhouse 100. Therefore, a sufficient amount of carbon dioxide can still be supplied to the inside of the agriculture greenhouse 100 when carbon dioxide is not sufficiently reserved in the absorption tank 6.

[0064] Furthermore, carbon dioxide is supplied from the absorption tank 6 and the auxiliary application device 9 by the blower 5. This enables reduction of local supply of carbon dioxide in the inside of the agriculture greenhouse 100.

[0065] Accordingly, carbon dioxide can be appropriately supplied to the inside of the agriculture greenhouse 100.

(2) Supply of carbon dioxide from the auxiliary application device 9 to the inside of the agriculture greenhouse 100 is stopped when the concentration of carbon dioxide inside the agriculture greenhouse 100 reaches an appropriate concentration as a consequence of receiving carbon dioxide from the auxiliary application device 9. This configuration reduces an excess operation of the auxiliary application device 9 and helps keep an appropriate concentration of carbon dioxide inside the agriculture greenhouse 100.

[0066] [4. Other Embodiment] (1) In the aforementioned embodiment, the flow path concentration censor 15C is located downstream of the second open-close valve 17B in the interior flow path 15. Nevertheless, the flow path concentration censor 15C may be located at a different position in the flow paths. Specifically, the

-20flow path concentration censor 15C may be located, for example, near the branching point to the third tank-flow path 20 in the interior flow path 15, in the third tank-flow path 20, or in the second tank-flow path 19.

[0067] (2) One function achieved by one element in the aforementioned embodiment may be divided and achieved by two or more elements; and two or more functions achieved by two or more elements may be achieved by one element. Additionally, a part of the configuration of the aforementioned embodiment may be omitted as long as the problem can be solved. It should be noted that any and all modes that are encompassed in the technical ideas defined by the languages in the scope of the claims are embodiments of the present disclosure.

[0068] [5. Corresponding Relationship with Scope of Claims]

The controller 7 and the open-close valves 12A, 14A, 15A, 15B, 16A, 17A, and 17B in the aforementioned embodiment correspond to one example of the supply-controller. The flow paths including at least the interior flow path 15 in the carbon dioxide application device 1 corresponds to one example of the carbon dioxide supply path. S200 and S225 in the carbon dioxide supply process correspond to one example of the function of the concentration detector. In addition, the first threshold value corresponds to one example of the threshold values B and C, and the second threshold value corresponds to one example of the threshold value A.

Claims

CONCLUSIONS

A carbon dioxide delivery device that serves as a main delivery device adapted to feed carbon dioxide contained in combustion exhaust gases to an interior of an agricultural greenhouse, the carbon dioxide delivery device comprising:

an absorption tank therein comprising an absorber unit adapted to absorb carbon dioxide in the combustion exhaust gases, flow-through equipment placed in a carbon dioxide supply path and adapted to cause gases in the carbon dioxide supply path to flow downstream, a supply controller adapted to carbon dioxide, is absorbed in the absorber unit in the absorption tank, to be fed to the inside of the agricultural greenhouse via the carbon dioxide supply path and through the flow-through equipment, and a concentration detector adapted to measure or estimate a first concentration of carbon dioxide inside the agricultural greenhouse and a second concentration of carbon dioxide supplied from the absorption tank to the inside of the agricultural greenhouse, the supply controller adapted to supply carbon dioxide from an auxiliary delivery device to the inside of the agricultural greenhouse via the carbon dioxide. oxide supply path and through the flow-through equipment if the second concentration of carbon dioxide is below a predetermined limit value (A) after a specified time has passed from a starting point in time when the carbon dioxide is supplied from the absorption tank to the inside of the agricultural greenhouse and is arranged to stop the supply of carbon dioxide from the auxiliary delivery device if, during the supply of carbon dioxide from the auxiliary delivery device to the inside of the agricultural greenhouse, the first concentration of carbon dioxide exceeds a predetermined limit value (B) that is greater than the limit value (A).

The carbon dioxide delivery device according to claim 1, wherein the second concentration of carbon dioxide is a concentration of carbon dioxide in a flow path that connects the absorption tank and the agricultural greenhouse.

The carbon dioxide delivery device according to claim 1 or 2,

Wherein, when carbon dioxide is supplied from the absorption tank to the agricultural greenhouse, the supply controller is arranged to stop the supply of carbon dioxide from the absorption tank to the inside of the agricultural greenhouse if the first concentration of carbon dioxide exceeds the limit value (B).

The carbon dioxide delivery device according to any of claims 1-3, wherein the supply controller is adapted to supply carbon dioxide from the absorption tank to the inside of the agricultural greenhouse via the carbon dioxide supply path and through the through-flow equipment if the The first concentration of carbon dioxide falls below the limit value (B) after the supply of carbon dioxide to the inside of the agricultural greenhouse has been stopped.

The carbon dioxide delivery device according to any of claims 1-4, wherein the auxiliary delivery device is arranged as a device for generating carbon dioxide by burning fuel and heating the inside of the agricultural greenhouse.

The carbon dioxide delivery device according to any of claims 1-5, wherein the auxiliary delivery device is arranged as a device to generate carbon dioxide by burning fuel, and wherein the supply controller is arranged to generate combustion exhaust gases generated by fuel combustion in the fuel auxiliary delivery device to flow downstream to the absorption tank through the carbon dioxide supply path and through the flow through equipment, and to cause carbon dioxide in the combustion exhaust gases to be absorbed by the absorber unit.

The carbon dioxide delivery device according to any one of claims 1-4, wherein the auxiliary delivery device is arranged as a cylinder for reserving carbon dioxide, and wherein the feed controller is arranged around carbon dioxide which has flowed out of the auxiliary delivery device and is diluted can be supplied with air to the inside of the agricultural greenhouse.

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