Carbon dioxide storage system

Abstract

To reduce the cost of installing a heat utilization device in conjunction with a carbon dioxide storage system. [Solution] A carbon dioxide storage system 10A, 10B, 10C for storing carbon dioxide in the ground S1 comprises: a dissolution processing unit 16 that dissolves carbon dioxide emitted from a carbon dioxide source 1 in water to produce dissolved carbon dioxide water; a water supply pipe 12 that connects water supply sources 11, 11A to the dissolution processing unit 16 and sends water for dissolving carbon dioxide from the water supply sources 11, 11A to the dissolution processing unit 16; an injection processing unit 18 that extends from the surface through the ground S1, S2 and injects the dissolved carbon dioxide water produced in the dissolution processing unit 16 into the ground S1; and a heat utilization system 20 that uses at least a portion of the water sent from the water supply sources 11, 11A to the dissolution processing unit 16 through the water supply pipe 12 as heat source water.

Description

Technical Field

[0001] The present disclosure relates to a carbon dioxide storage system, and particularly relates to a technique suitable for underground storage of carbon dioxide.

Background Art

[0002] In recent years, the treatment of carbon dioxide (CO₂) emitted from fossil fuels used in business establishments such as factories has become an issue. As a technique for treating CO₂, a CO₂ storage system is known, which stores or reserves CO₂ underground by pumping underground well water from the ground through a water pumping well, dissolving CO₂ in the pumped well water, and injecting the water with dissolved CO₂ (hereinafter referred to as CO₂ dissolved water) into the ground through an injection well (see, for example, Patent Document 1, etc.).

Prior Art Literature

Patent Literature

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] Business establishments such as factories that emit CO₂ sometimes have a water-cooled heat utilization system that uses well water pumped from a water pumping well as raw hot water. When both a CO₂ storage system and a heat utilization system are installed in a business establishment, providing separate water pumping wells for pumping well water leads to the problem that costs such as construction costs and maintenance management costs increase.

[0005] The technique of the present disclosure has been made in view of the above circumstances, and an object thereof is to provide a technique that can effectively suppress costs when a heat utilization system is installed alongside a CO₂ storage system.

Means for Solving the Problem

[0006] The carbon dioxide storage system described herein is A carbon dioxide storage system (10A, 10B, 10C) that stores carbon dioxide underground (S1), A dissolution processing unit (16) that dissolves carbon dioxide emitted from a carbon dioxide source (1) in water to produce carbon dioxide dissolved water, The water supply source (11, 11A) and the dissolution processing unit (16) are connected by a water supply pipe (12) that sends water for dissolving carbon dioxide from the water supply source (11, 11A) to the dissolution processing unit (16), An injection processing unit (18) extends from above ground into the ground (S1, S2) and injects the carbon dioxide dissolved water generated in the dissolution processing unit (16) into the ground (S1), The system includes a heat utilization system (20) that uses at least a portion of the water sent from the water supply source (11, 11A) to the dissolution processing unit (16) through the water supply piping (12) as heat source water. It is characterized by the following:

[0007] In other embodiments of the carbon dioxide storage systems of this disclosure, The aforementioned heat utilization system (20) is A heat source water supply pipe (31) branches off from the water supply pipe (12) and is connected to the heat exchange section (52) of the heat utilization device (20), and supplies at least a portion of the water flowing through the water supply pipe (12) to the heat exchange section (52) as heat source water, The heat exchange section (52) and the water supply pipe (12) downstream of the branching point between the water supply pipe (12) and the heat source water supply pipe (31) are connected, and the heat source water return pipe (32) returns the water supplied to the heat exchanger (52) to the water supply pipe (12), It is desirable to have an additional supply pipe (71) that connects the water supply source (11, 11A) and the water supply pipe (12) downstream of the branch section, and supplies additional water from the water supply source (11, 11A) to the dissolution processing section (16).

[0008] In other embodiments of the carbon dioxide storage systems of this disclosure, The heat utilization system (20) preferably includes a heat pump device (50) that uses water supplied from the water supply source (11, 11A) as heat source water.

[0009] In other embodiments of the carbon dioxide storage systems of this disclosure, The water supply source (11,11A) is preferably a water storage tank (11) that stores surface water.

[0010] In other embodiments of the carbon dioxide storage systems of this disclosure, The dissolution processing unit (16) preferably generates the carbon dioxide-dissolved water by dissolving the carbon dioxide, which has been compressed into microbubbles by the compressor (15), into water.

[0011] In other embodiments of the carbon dioxide storage systems of this disclosure, The injection section (18) is preferably an injection well (18) or a permeable well that penetrates from the surface to the aquifer (S1).

[0012] In the above description, the reference numerals used in the embodiments are indicated in parentheses next to the constituent elements corresponding to the embodiments in order to aid in understanding this disclosure; however, each constituent element is not limited to the embodiments defined by the aforementioned reference numerals. [Effects of the Invention]

[0013] The technology disclosed herein makes it possible to effectively reduce the costs associated with installing a heat utilization system in conjunction with a CO2 storage system. [Brief explanation of the drawing]

[0014] [Figure 1] This is a schematic overall diagram showing a carbon dioxide storage system according to the first embodiment. [Figure 2] This is a schematic overall diagram showing a carbon dioxide storage system according to the second embodiment. [Figure 3] This is a schematic overall diagram showing a modified carbon dioxide storage system. Mode for Carrying Out the Invention

[0015] Hereinafter, the carbon dioxide storage system according to the present embodiment will be described with reference to the accompanying drawings.

[0016] [First Embodiment] FIG. 1 is a schematic overall configuration diagram showing the carbon dioxide storage system 10A according to the first embodiment.

[0017] As shown in FIG. 1, the carbon dioxide storage system 10A implements so-called Carbon dioxide Capture and Storage (CCS), in which CO2 discharged from a business site 1 such as a factory is recovered and dissolved in water, and CO2-dissolved water obtained by dissolving CO2 is injected into the ground for storage. The business site 1 is an example of the carbon dioxide generation source in the present disclosure.

[0018] The carbon dioxide storage system 10A includes a water storage tank 11, a water supply pipe 12, a pump 13, a CO2 supply pipe 14, a compressor 15, a pressure tank 16, a dissolved water pipe 17, and an injection well 18. The pressure tank 16 is an example of the dissolution treatment section in the present disclosure, and the injection well 18 is an example of the injection treatment section in the present disclosure.

[0019] The water storage tank 11 stores surface water. Here, examples of the surface water include rainwater that has flowed into side ditches 5 provided in or around the business site 1, or river water pumped from a river 6 or the like by an unillustrated water pump or the like.

[0020] The water supply pipe 12 connects the water storage tank 11 and the pressure tank 16. The pump 13 is provided in the water supply pipe 12. It is configured such that when the pump 13 is driven, the water (surface water) stored in the water storage tank 11 is supplied (pressure-fed) to the pressure tank 16 via the water supply pipe 12.

[0021] The CO2 supply piping 14 connects the CO2 discharge section 2 of the business facility 1 to the pressure tank 16. The CO2 supply piping 14 is equipped with a compressor 15 for compressing the CO2 sent from the CO2 discharge section 2 through the CO2 supply piping 14.

[0022] The pressure tank 16 generates CO2-dissolved water by dissolving CO2, which has been compressed into microbubbles by the compressor 15, into water supplied through the water supply pipe 12. An injection well 18 is connected to the pressure tank 16 via a dissolved water pipe 17. Alternatively, CO2-dissolved water may be generated by dissolving CO2 in water without microbubbling it. In this case, a pump to supply CO2 to the CO2 supply pipe 14 can be installed instead of the compressor 15.

[0023] The injection well 18 is a well for injecting CO2-dissolved water into the aquifer S. The injection well 18 is formed by penetrating from the surface down to the aquifer S1 (for example, a gravel layer below the groundwater level, deeper than the impermeable layer S2). The CO2-dissolved water generated by the pressure tank 16 is injected (pressurized) into the aquifer S1 through the injection well 18. The CO2-dissolved water injected from the injection well 18 gradually settles in the aquifer S1.

[0024] In this embodiment, the carbon dioxide storage system 10A is configured as a composite system that includes a heat utilization system 20.

[0025] The heat utilization system 20 uses surface water such as rainwater stored in the water storage tank 11 as a heat source to operate at least one heat load device 60 located on the premises of the business establishment 1 or in surrounding buildings 8. The heat load device 60 is not particularly limited, but examples include an air conditioning system 61 and an industrial process cooling system 62.

[0026] The heat utilization system 20 comprises a heat source water supply unit 30, a heat transfer medium circulation unit 40, and a heat pump unit 50. The heat transfer medium circulation unit 40 is equipped with the aforementioned heat load device 60.

[0027] The heat source water supply unit 30 comprises a heat source water supply pipe 31, a heat source water return pipe 32, and a heat source water pump 33 provided on either the heat source water supply pipe 31 or the heat source water return pipe 32. Depending on the discharge capacity of the pump 13 provided in the carbon dioxide storage system 10B, the heat source water pump 33 may be omitted. In addition, a switching valve (not shown) for switching between supplying or stopping heat source water may be provided on either the heat source water supply pipe 31 or the heat source water return pipe 32. The switching valve may be a flow control valve capable of adjusting the flow rate of heat source water.

[0028] The heat source water supply pipe 31 branches off from the water supply pipe 12 and is connected to the first heat exchange section 52 of the heat pump unit 50. The heat source water return pipe 32 connects the first heat exchange section 52 to the water supply pipe 12. The heat source water return pipe 32 joins the water supply pipe 12 downstream of the branching point between the water supply pipe 12 and the heat source water supply pipe 31. The heat source water supply pipe 31 functions to supply at least a portion of the water (surface water) flowing through the water supply pipe 12 to the first heat exchange section 52, and to return the water that has exchanged heat with the first heat transfer medium R1 (described later) in the first heat exchange section 52 to the water supply pipe 12 through the heat source water return pipe 32.

[0029] The heat transfer medium circulation unit 40 includes a heat transfer medium supply pipe 41 for sending the second heat transfer medium R2 from the second heat exchange section 53 of the heat pump unit 50 to the heat load device 60, a heat transfer medium return pipe 42 for returning the second heat transfer medium R2 from the heat load device 60 to the second heat exchange section 53, and a heat transfer medium pump 43 provided in either the heat transfer medium supply pipe 41 or the heat transfer medium return pipe 42. When the heat transfer medium pump 43 is driven, the second heat transfer medium R2, which has undergone heat exchange with the first heat transfer medium R1 in the second heat exchange section 53, is sent to the heat load device 60 through the heat transfer medium supply pipe 41, and then returned to the second heat exchange section 53 through the heat transfer medium return pipe 42, thus circulating.

[0030] The heat pump unit 50 includes a heat medium circulation pipe 51 for circulating a first heat medium R1, a first heat exchange section 52 and a second heat exchange section 53 provided in the heat medium circulation pipe 51, a heat medium compressor 54 provided in the heat medium circulation pipe 51, and an expansion valve 55 provided in the heat medium circulation pipe 51. The heat medium circulation pipe 51 is also provided with a four-way valve (not shown) for reversing the circulation direction of the first heat medium R1.

[0031] When the heat pump unit 50 operates the air conditioning unit 61 of the heat load device 60 in "cooling mode" (refrigeration cycle), it circulates the first heat transfer medium R1, which is pressurized from the heat transfer medium compressor 54, in the order of the first heat exchange section 52, the expansion valve 55, and the second heat exchange section 53. That is, the high-temperature, high-pressure first heat transfer medium R1, compressed by the heat transfer medium compressor 54, raises the temperature of the heat source water in the first heat exchange section 52. The first heat transfer medium R1, which has raised the temperature of the heat source water, is cooled in the expansion valve 55 and sent to the second heat exchange section 53, where it cools the second heat transfer medium R2 before being sent to the heat transfer medium compressor 54. On the other hand, when the air conditioning unit 61 is operated in "heating mode" (heat pump cycle), the heat pump unit 50 circulates the first heat transfer medium R1, which is pressurized from the heat transfer medium compressor 54, in the order of the second heat exchange section 53, the expansion valve 55, and the first heat exchange section 52. Specifically, the high-temperature, high-pressure first heat transfer medium R1, compressed by the heat transfer medium compressor 54, raises the temperature of the second heat transfer medium R2 in the second heat exchange section 53. The first heat transfer medium R1, which has raised the temperature of the second heat transfer medium R2, is cooled by the expansion valve 55 and sent to the first heat exchange section 52, where the heat source water is cooled and then sent to the heat transfer medium compressor 54.

[0032] According to the first embodiment described above, the carbon dioxide storage system 10A is configured as a composite system equipped with a heat utilization system 20. The heat utilization system 20 is equipped with a water-cooled heat pump unit 50 and is configured to use surface water, before the carbon dioxide storage system 10A dissolves CO2, as the heat source water to operate heat load devices 60 such as an air conditioner 61. In other words, by using surface water such as rainwater stored in the water storage tank 11 for both underground CO2 storage and the heat utilization system 20, it becomes unnecessary to install pumping wells to draw up water for dissolving CO2 and heat source water. This makes it possible to simplify and reduce the cost of the entire composite system, and furthermore, it becomes possible to effectively reduce maintenance costs related to operation.

[0033] Furthermore, rainwater treatment within the premises of business establishments such as 1 may require infiltration treatment on-site, depending on the capacity limitations of the sewage system. In particular, the increasing frequency of concentrated rainfall in recent years has heightened the need for rainwater infiltration treatment. According to the carbon dioxide storage system 10A of this embodiment, surface water such as rainwater stored in the storage tank 11 can be effectively utilized for underground CO2 storage and as a heat source for the heat utilization system 20, thereby enabling effective CCS, rainwater treatment, and energy saving with a simple configuration.

[0034] Furthermore, when the air conditioning unit 61 is operated in "heating mode," cold water cooled in the first heat exchange section 52 of the heat pump unit 50 is sent to the pressure tank 16, which effectively improves the CO2 dissolution efficiency.

[0035] [Second Embodiment] Figure 2 is a schematic overall diagram showing the carbon dioxide storage system 10B according to the second embodiment.

[0036] The carbon dioxide storage system 10B of the second embodiment is configured as a composite system including a heat utilization system 20, similar to the first embodiment. Components identical to those in the carbon dioxide storage system 10A and the heat utilization system 20 of the first embodiment are denoted by the same reference numerals, and their functions are also the same. Therefore, their descriptions will be omitted below.

[0037] The carbon dioxide storage system 10B is equipped with a water temperature adjustment mechanism 70 that can adjust the temperature of the water in which CO2 is dissolved (hereinafter referred to as water temperature). Specifically, the water temperature adjustment mechanism 70 includes an additional water supply pipe 71, a flow control valve 72, a water temperature sensor 73, and a control device 74.

[0038] The additional water supply pipe 71 supplies additional water to adjust the water temperature to the water that is returned from the heat source water supply unit 30 to the water supply pipe 12 and supplied to the pressure tank 16. Specifically, the additional water supply pipe 71 connects the water storage tank 11 and the water supply pipe 12. The location where the additional water supply pipe 71 is connected to the water supply pipe 12 is not particularly limited, as long as it is downstream of the branching point between the heat source water supply pipe 31 and the water supply pipe 12. Preferably, the additional water supply pipe 71 is connected to the water supply pipe 12 upstream of the pump 13. When the additional water supply pipe 71 is connected to the water supply pipe 12 downstream of the pump 13, it is desirable to provide a separate pump for the additional water supply pipe 71, separate from the pump 13.

[0039] The flow control valve 72 is installed in the additional water supply pipe 71 and adjusts the amount of water added from the water storage tank 11 to the water supply pipe 12 through the additional water supply pipe 71. The operation of the flow control valve 72 is controlled according to commands from the control device 74. The water temperature sensor 73 is installed downstream of the junction of the water supply pipe 12 with the heat source water return pipe 32 and the junction with the additional water supply pipe 71, and acquires the water temperature Tw of the water supplied to the pressure tank 16. The water temperature Tw detected by the water temperature sensor 73 is repeatedly transmitted to the control device 74 at a predetermined period.

[0040] The control unit 74 is a so-called microcomputer equipped with a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), and an interface IF, etc. ROM is non-volatile memory that stores data necessary for the CPU to execute various programs. RAM is volatile memory that provides a work area that is expanded when various programs are executed by the CPU. The interface IF is a communication device for communicating with external devices.

[0041] The control device 74 is connected to a flow control valve 72 and a water temperature sensor 73, etc., in a communication manner. In this embodiment, the control device 74 performs water temperature control to control the water temperature Tw supplied to the pressure tank 16. Specifically, for example, in "cooling mode" when the water supplied as heat source water to the first heat exchange unit 52 of the heat pump unit 50 is heated by the first heat transfer medium R1, the control device 74 controls the flow control valve 72 so that the water temperature Tw detected by the water temperature sensor 73 is below a predetermined threshold water temperature Twv. The control device 74 controls the flow control valve 72 so that the amount of water added from the water storage tank 11 through the additional water supply pipe 71 increases as the water temperature Tw rises above the threshold water temperature Twv. This effectively suppresses the water temperature Tw supplied to the pressure tank 16 from rising in "cooling mode".

[0042] In other words, according to the second embodiment, similar to the first embodiment, it becomes possible to simplify the entire composite system, reduce costs, lower maintenance costs, and save energy, while effectively suppressing the decrease in dissolved CO2 in "cooling mode".

[0043] [others] Furthermore, this disclosure is not limited to the embodiments described above, and can be modified and implemented as appropriate without departing from the spirit of this disclosure.

[0044] For example, as shown in Figure 3, the modified carbon dioxide storage system 10C may be configured to include a pumping well 11A for pumping up groundwater instead of a water storage tank 11. In this case as well, by sharing the pumping well 11A with the heat utilization system 20, it is possible to effectively reduce installation costs and maintenance costs compared to a configuration in which a pumping well is provided separately.

[0045] Furthermore, although the heat utilization system 20 has been described as comprising a heat pump unit 50, other heat utilization devices other than a heat pump may be provided as long as the configuration allows for the use of surface water stored in the water storage tank 11 as heat source water. Also, in the first embodiment, the surface water supplied to the first heat exchange section 52 of the heat pump unit 50 as heat source water was described as being returned to the water supply pipe 12 through the heat source water return pipe 32, but it may be configured to be returned to the water storage tank 11. In addition, the water injection well 18 may be a permeable well that penetrates from the ground to the aquifer S1. Furthermore, the number of water injection wells 18 and water storage tanks 11 is not limited to the illustrated example, and multiple wells can be installed depending on the size of the business establishment 1 and the surrounding environment. In addition, although the carbon dioxide source has been exemplified as a business establishment 1 such as a factory, the technology of this disclosure can be broadly applied to other carbon dioxide sources that emit carbon dioxide. [Explanation of Symbols]

[0046] 1...Business premises, 2...CO2 emission section, 5...Drainage ditch, 6...River, 8...Building, 10A, 10B, 10C...Carbon dioxide storage system, 11...Water storage tank, 12...Water supply piping, 13...Pump, 14...CO2 supply piping, 15...Compressor, 16...Pressure tank, 25...Material storage section, 17...Dissolved water piping, 18...Injection well, 20...Heat utilization system, 30...Heat source water supply unit, 31...Heat source water supply piping, 32...Heat source water return Piping, 33…Heat source water pump, 40…Heat transfer fluid circulation unit, 41…Heat transfer fluid supply piping, 42…Heat transfer fluid return piping, 50…Heat pump unit, 51…Heat transfer fluid circulation piping, 52…First heat exchange section, 53…Second heat exchange section, 54…Heat transfer fluid compressor, 55…Expansion valve, 70…Water temperature adjustment mechanism, 71…Additional water supply piping, 72…Flow control valve, 73…Water temperature sensor, 74…Control device, S1…Aquifer, S2…Impermeable layer

Claims

1. A carbon dioxide storage system that stores carbon dioxide underground, A dissolution processing unit that dissolves carbon dioxide emitted from a carbon dioxide source in water to produce carbon dioxide-dissolved water, A water supply pipe connects the water supply source and the dissolution processing unit, and supplies water for dissolving the carbon dioxide from the water supply source to the dissolution processing unit. An injection processing unit extends from above ground into the ground and injects the carbon dioxide-dissolved water produced in the dissolution processing unit into the ground, The system includes a heat utilization system that uses at least a portion of the water sent from the water supply source through the water supply piping to the dissolution processing unit as heat source water. A carbon dioxide storage system characterized by the following:

2. A carbon dioxide storage system according to claim 1, The aforementioned heat utilization system is A heat source water supply pipe is branched from the water supply pipe and connected to the heat exchange section of the heat utilization device, and supplies at least a portion of the water flowing through the water supply pipe to the heat exchange section as heat source water, The heat exchange section is connected to the water supply pipe downstream of the branching point between the water supply pipe and the heat source water supply pipe, and the heat source water return pipe returns the water supplied to the heat exchanger to the water supply pipe, The system includes an additional supply pipe that connects the water supply source to the water supply piping downstream of the branching section and supplies additional water from the water supply source to the dissolution processing section. A carbon dioxide storage system characterized by the following:

3. A carbon dioxide storage system according to claim 1 or 2, The heat utilization system includes a heat pump device that uses water supplied from the water supply source as the heat source water. A carbon dioxide storage system characterized by the following:

4. A carbon dioxide storage system according to claim 1, The water supply source is a reservoir that stores surface water. A carbon dioxide storage system characterized by the following:

5. A carbon dioxide storage system according to claim 1, The dissolution processing unit generates the carbon dioxide-dissolved water by dissolving carbon dioxide, which has been compressed into microbubbles by a compressor, into water. A carbon dioxide storage system characterized by the following:

6. A carbon dioxide storage system according to claim 1, The injection section is an injection well or permeable well that penetrates from the ground surface to the aquifer. A carbon dioxide storage system characterized by the following:

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