Carbon dioxide storage device

Abstract

To provide a carbon dioxide storage device that stores carbon dioxide in the ground.SOLUTION: A carbon dioxide storage device 20 comprises: pressing-in piping P1 for pressing liquefied carbon dioxide in the ground from the ground; a pressing-in pump 2 for pressing the liquefied carbon dioxide in the pressing-in piping P1; a first control valve 3 for controlling a flow rate of liquefied carbon dioxide flowing in the pressing-in piping P1; a first flowmeter SR1 measuring the flow rate of the liquefied carbon dioxide flowing in the pressing-in piping P1; pumping-up piping P2 for pumping up groundwater from underground to the ground; a second control valve 7 for controlling a flow rate of the groundwater flowing in the pumping-up piping P2; a second flowmeter SR2 measuring a flow rate of liquid included in the groundwater flowing in the pumping-up piping P2; and a control unit 1 for controlling the second control valve 7 to increase a flow rate of the liquid measured by the second flowmeter SR2 if a flow rate of the liquefied carbon dioxide measured by the first flowmeter SR1 is less than a predetermined threshold.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a carbon dioxide storage device that stores carbon dioxide underground. [Background technology]

[0002] Generally, carbon dioxide is being stored underground to reduce the amount of carbon dioxide released into the atmosphere. Summary of the Invention [Problem to be solved by the invention]

[0003] However, storing carbon dioxide underground is not easy, and studies into its practical application have only just begun. It is an object of embodiments of the present invention to provide a carbon dioxide sequestration device for storing carbon dioxide underground. [Means for solving the problem]

[0004] A carbon dioxide storage device according to an aspect of the present invention comprises an injection pipe for injecting liquefied carbon dioxide underground from above ground, an injection pump for injecting liquefied carbon dioxide into the injection pipe, a first control valve for adjusting the flow rate of the liquefied carbon dioxide flowing into the injection pipe, a first flow meter for measuring the flow rate of the liquefied carbon dioxide flowing into the injection pipe, a pumping pipe for pumping groundwater from underground to the surface, a second control valve for adjusting the flow rate of the groundwater flowing into the pumping pipe, a second flow meter for measuring the flow rate of liquid contained in the groundwater flowing into the pumping pipe, and a control unit that controls the second control valve so that the flow rate of the liquid measured by the second flow meter increases when the flow rate of the liquefied carbon dioxide measured by the first flow meter falls below a predetermined threshold. [Effects of the Invention]

[0005] According to an embodiment of the present invention, it is possible to provide a carbon dioxide sequestration device that sequesters carbon dioxide underground. [Brief explanation of the drawings]

[0006] [Figure 1] 1 is a diagram showing the configuration of a carbon dioxide storage device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a configuration diagram showing the configuration of a control device according to the present embodiment. [Figure 3] 3 is a flowchart showing an example of a method for storing liquefied carbon dioxide underground using the carbon dioxide storage device according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0007] (Embodiment) 1 is a diagram showing the configuration of a carbon dioxide storage device 20 according to an embodiment of the present invention. Note that the same parts in the drawings are given the same reference numerals, and duplicated explanations will be omitted as appropriate.

[0008] The carbon dioxide storage device 20 is a device for storing carbon dioxide underground. The carbon dioxide storage device 20 injects liquefied carbon dioxide into the ground by utilizing abandoned wells, which are abandoned mines from which crude oil is not currently being extracted. The abandoned wells may be located on the seabed or on land. The carbon dioxide storage device 20 also has the function of actively pumping water while injecting liquefied carbon dioxide into the ground. The liquefied carbon dioxide to be injected may be at any pressure and temperature, as long as it is in a liquid state.

[0009] The location where the liquefied carbon dioxide is stored is where crude oil was accumulated. Crude oil before mining is often contained in reservoir rock beneath an impermeable cap rock. Therefore, the carbon dioxide storage device 20 injects liquefied carbon dioxide beneath the cap rock. This causes the liquefied carbon dioxide to be stored in the space where the crude oil was accumulated before mining. Note that the carbon dioxide storage device 20 may store liquefied carbon dioxide anywhere underground as long as it can store the liquefied carbon dioxide underground.

[0010] The carbon dioxide storage device 20 includes a control device 1, an injection pump 2, a first control valve 3, an injection blowout preventer 4, a pumping blowout preventer 5, a gas separator 6, a second control valve 7, a liquid buffer tank 8, a separated liquid tank 9, a third control valve 10, a separated gas tank 11, three flow meters SR1, SR2, and SR3, and a water level sensor SR4.

[0011] Additionally, any type of sensor may be provided at any location in the carbon dioxide sequestration device 20 for the purpose of monitoring, etc. For example, a pressure sensor may be provided to measure the pressure of the liquefied carbon dioxide being injected.

[0012] The control device 1 is a device for controlling the carbon dioxide storage device 20. The control device 1 mainly uses a computer to control and monitor each device that constitutes the carbon dioxide storage device 20. For example, the control device 1 controls the operation of each device that constitutes the carbon dioxide storage device 20 based on the detection results detected by each of the sensors SR1 to SR4. The control device 1 operates each device by outputting an operation command to operate each device.

[0013] The injection pump 2, first control valve 3, injection blowout preventer 4, and first flow meter SR1 are devices for injecting liquefied carbon dioxide underground from above ground, and are installed in a path (piping P1, etc.) through which the liquefied carbon dioxide flows.

[0014] The injection pump 2 is a pump that applies pressure to pump liquefied carbon dioxide into the ground. The suction side of the injection pump 2 is connected to a supply source of liquefied carbon dioxide (for example, a liquefied carbon dioxide tank) that is stored to be buried underground.

[0015] The first control valve 3 is provided in a pipe P1 connected to the discharge side of the pressure pump 2. The opening and closing and aperture of the first control valve 3 are controlled by the control device 1. By controlling the aperture of the first control valve 3, the flow rate of the liquefied carbon dioxide is controlled.

[0016] The injection blowout preventer 4 is installed on the liquefied carbon dioxide pipe P1 near the surface (for example, the seabed). The injection blowout preventer 4 is a blowout preventer (BOP) that prevents the liquefied carbon dioxide from backflowing and blowing out. The injection blowout preventer 4 automatically closes when gas erupts. The underground side of the injection blowout preventer 4 is connected to the pipe P1 for sending the liquefied carbon dioxide to a location where it will be stored underground.

[0017] The first flow meter SR1 is provided in the pipe P1 between the first control valve 3 and the injection blowout preventer 4, but may be provided anywhere on the discharge side of the first control valve 3. The first flow meter SR1 is a sensor that measures the flow rate of the liquefied carbon dioxide being injected. The first flow meter SR1 transmits the measured flow rate of the liquefied carbon dioxide to the control device 1. The flow rate measured by the first flow meter SR1 is the volume or mass flowing per fixed time period. Here, the fixed time period may be determined arbitrarily, or may be a unit time period.

[0018] The pumping blowout preventer 5, gas separator 6, second control valve 7, liquid buffer tank 8, separation liquid tank 9, second flow meter SR2, and water level sensor SR4 are equipment for pumping groundwater and are installed in the path through which the groundwater flows (piping P2, etc.).

[0019] The carbon dioxide storage device 20 pumps up groundwater in a space connected to the space for storing liquefied carbon dioxide. However, to avoid pumping up the injected liquefied carbon dioxide, the pipe P2 for pumping up the groundwater is buried in the ground surface at a location away from the pipe P1 for injecting the liquefied carbon dioxide. Generally, groundwater contains various impurities such as gas, oil, mud, or gravel. In addition to the above-mentioned equipment, equipment such as a pump for pumping up groundwater may be provided.

[0020] The pumping blowout preventer 5 is installed on the groundwater pipe P2 near the surface (e.g., the seabed). The pumping blowout preventer 5 is a blowout preventer (BOP) that prevents groundwater from blowing out. The pumping blowout preventer 5 automatically closes when gas is released. The underground side of the pumping blowout preventer 5 is connected to the pipe P2 that reaches the location where groundwater is stored.

[0021] The gas separator 6 is installed in the pipe P2 between the pumping blowout preventer 5 and the liquid buffer tank 8. The gas separator 6 has the function of separating gas from liquid. The gas separator 6 is provided with an outlet for discharging the separated gas to the outside. The outlet of the gas separator 6 is connected to the pipe P3 through which the gas flows. Under normal circumstances, the gas separator 6 sends the pumped groundwater directly to the liquid buffer tank 8. When the amount of gas contained in the pumped groundwater increases, the gas separator 6 separates the gas from the groundwater under the control of the control device 1, and sends the groundwater from which the gas has been removed to the liquid buffer tank 8.

[0022] The second control valve 7 is provided in the pipe P2 connecting the gas separator 6 and the liquid buffer tank 8. The opening and closing and aperture of the second control valve 7 are controlled by the control device 1. By controlling the aperture of the second control valve 7, the flow rate of the groundwater being pumped is controlled. The second control valve 7 may be provided anywhere in the pipe P2 between the pumping blowout preventer 5 and the liquid buffer tank 8.

[0023] The liquid buffer tank 8 is a tank that temporarily stores the pumped groundwater. The liquid buffer tank 8 separates the groundwater into gas, liquid, and sediment using gravity. Gas refers to the various gases contained in the groundwater. Liquid is mainly water, and also contains oil, etc. Sediment refers to mud, gravel, etc. The sediment that settles to the bottom of the liquid buffer tank 8 is periodically removed. The liquid buffer tank 8 sends the liquid, from which the gas and sediment have been separated, to the separated liquid tank 9.

[0024] The water level sensor SR4 is provided inside the liquid buffer tank 8. The water level sensor SR4 detects the level of the liquid stored in the liquid buffer tank 8 and transmits the detected water level to the control device 1. The inside of the liquid buffer tank 8 is kept airtight, and as the amount of gas contained in the liquid increases, the water level decreases. Therefore, the control device 1 determines the amount of gas inside the liquid buffer tank 8 based on the water level detected by the water level sensor SR4.

[0025] Note that any sensor may be provided, not limited to the water level sensor SR4, as long as it can grasp the amount of gas inside the liquid buffer tank 8. For example, a sensor that detects gas inside the liquid buffer tank 8 may be used instead of the water level sensor SR4. Also, the sensor is not limited to a sensor that measures the amount of gas, and any sensor may be provided as long as it can determine that the amount of gas has exceeded a predetermined amount.

[0026] The separated liquid tank 9 accumulates the liquid sent from the liquid buffer tank 8 and separates it into oil and water. The separated liquid tank 9 sends the separated water and oil separately to treatment equipment or the like. The separately treated water and oil are discharged to the outside. The water and oil may also be treated so that they can be reused.

[0027] The second flow meter SR2 is provided in the pipe P2 through which the liquid flows, connecting the liquid buffer tank 8 and the separated liquid tank 9. The second flow meter SR2 is a sensor that measures the flow rate of the liquid sent from the liquid buffer tank 8 to the separated liquid tank 9. In other words, the second flow meter SR2 measures the flow rate of only the liquid contained in the groundwater. The second flow meter SR2 transmits the measured flow rate of the liquid to the control device 1. In other respects, the second flow meter SR2 is the same as the first flow meter SR1.

[0028] The third control valve 10, the separated gas tank 11, and the third flow meter SR3 are devices for extracting the gas separated from the groundwater by the gas separator 6, and are provided in the path (piping P3, etc.) through which the separated gas flows.

[0029] The third control valve 10 is provided in a pipe P3 through which the gas separated from the gas separator 6 flows to a separated gas tank 11. The opening and closing of the third control valve 10 is controlled by a control device 1. By controlling the opening and closing of the third control valve 10, gas is removed from the groundwater. The opening degree of the third control valve 10 may be controlled to adjust the flow rate of gas discharged from the gas separator 6.

[0030] The separated gas tank 11 is a tank that stores the gas separated by the gas separator 6. The gas stored in the separated gas tank 11 may be subjected to any treatment, may be reused, or may be discarded.

[0031] The third flow meter SR3 is provided in the gas pipe P3 that connects the gas separator 6 and the separated gas tank 11. The third flow meter SR3 is a sensor that measures the flow rate of gas sent from the gas separator 6 to the separated gas tank 11. The third flow meter SR3 transmits the measured gas flow rate to the control device 1. In other respects, the third flow meter SR3 is the same as the first flow meter SR1.

[0032] FIG. 2 is a configuration diagram showing the configuration of the control device 1 according to this embodiment.

[0033] The control device 1 includes an injection flow rate control unit 21, a pumping control unit 22, and a degassing control unit .

[0034] The injection flow rate control unit 21 controls the first control valve 3 based on the planned flow rate F0 of liquefied carbon dioxide, the measured flow rate F1 of liquefied carbon dioxide measured by the first flow meter SR1, and the flow rate F3 of gas separated from groundwater measured by the third flow meter SR3. For example, the injection flow rate control unit 21 outputs an operation command to the first control valve 3 to operate the first control valve 3.

[0035] The planned flow rate F0 of liquefied carbon dioxide is the flow rate of liquefied carbon dioxide that serves as a reference for the pre-planned injection. The planned flow rate F0 is input to the injection flow rate control unit 21 before the injection of liquefied carbon dioxide begins. For example, the planned flow rate F0 is the flow rate required for liquefied carbon dioxide to be injected into the ground as planned. Specifically, by adjusting the flow rate of liquefied carbon dioxide so that the flow rate of liquefied carbon dioxide during injection always exceeds the planned flow rate F0, liquefied carbon dioxide can be injected into the ground as planned.

[0036] At the start of injection, the injection flow rate control unit 21 opens the first control valve 3, and at the end of injection, closes the first control valve 3. During injection, the injection flow rate control unit 21 controls the opening degree of the first control valve 3 so that the measured flow rate F1 exceeds the planned flow rate F0.

[0037] If the gas flow rate F3 increases suddenly, the injection flow rate control unit 21 urgently closes the first control valve 3. In this way, the injection flow rate control unit 21 performs control to deal with an emergency situation in which gas suddenly gushes out from the pipe P2 for pumping up groundwater.

[0038] The pumping control unit 22 controls the second control valve 7 based on the planned flow rate F0 of liquefied carbon dioxide, the measured flow rate F1 of liquefied carbon dioxide measured by the first flow meter SR1, the liquid flow rate F2 of groundwater measured by the second flow meter SR2, and the gas flow rate F3 measured by the third flow meter SR3.

[0039] For example, if the measured flow rate F1 does not exceed the planned flow rate F0 even when the opening of the first control valve 3 is maximized, the pumping control unit 22 opens the second control valve 7 and starts pumping groundwater. To determine that the opening of the first control valve 3 is maximized, the pumping control unit 22 may receive information from the injection flow rate control unit 21 or may receive a signal from the first control valve 3 indicating the operation status.

[0040] The pumping control unit 22 controls the aperture of the second control valve 7 so that the measured flow rate F1 always exceeds the planned flow rate F0. The pumping control unit 22 increases the aperture of the second control valve 7, thereby increasing the flow rate of the groundwater to be pumped. This increases the amount of space in the ground where liquefied carbon dioxide can be stored, making it easier to inject the liquefied carbon dioxide into the ground.

[0041] Furthermore, if the gas flow rate F3 increases suddenly, the pumping control unit 22 urgently closes the second control valve 7. In this way, the pumping control unit 22 performs control to deal with an emergency situation in which gas suddenly gushes out from the pipe P2 for pumping up groundwater.

[0042] The gas degassing control unit 23 controls the third control valve 10 based on the gas flow rate F3 separated from the groundwater measured by the third flow meter SR3 and the liquid level L1 in the liquid buffer tank 8 detected by the water level sensor SR4.

[0043] For example, the degassing control unit 23 determines the amount of gas accumulated in the liquid buffer tank 8 based on the liquid level L1 detected by the water level sensor SR4. If the amount of accumulated gas exceeds a predetermined threshold, the degassing control unit 23 opens the third control valve 10 to perform degassing to remove gas from the groundwater. If the degassing control unit 23 determines, based on the detection signal received from the water level sensor SR4, that the water level has exceeded the predetermined water level threshold, the degassing control unit 23 opens the third control valve 10.

[0044] When the gas flow rate F3 measured by the third flow meter SR3 falls below a predetermined gas flow rate threshold, the degassing control unit 23 closes the third control valve 10 to terminate degassing. For example, the gas flow rate threshold is a value at which it can be assumed that there is no gas flow rate F3. The degassing control unit 23 may terminate degassing based on the measurement results obtained by measuring the gas flow rate F3 for a certain period of time. This allows degassing to continue even if the gas flow rate F3 temporarily falls below the threshold when there is an intermittent gas flow rate F3.

[0045] Furthermore, if the gas flow rate F3 increases suddenly, the gas venting control unit 23 urgently opens the third control valve 10. In this way, the gas venting control unit 23 performs control to deal with an emergency situation in which gas suddenly gushes out from the pipe P2 for pumping up groundwater.

[0046] An example of a method for storing liquefied carbon dioxide underground using the carbon dioxide storage device 20 according to this embodiment will be described with reference to Figure 3. Control for storing liquefied carbon dioxide is mainly performed by the control device 1. It should be noted that the carbon dioxide storage device 20 may be used in any way as long as it can store liquefied carbon dioxide underground, and is not limited to the procedures and controls described here.

[0047] Here, it is assumed that each of the sensors SR1 to SR4 constantly detects the detection target and constantly transmits the detection results to the control device 1. Furthermore, even during the procedure described here, if all of the planned liquefied carbon dioxide has been stored, the control device 1 will end the storage of liquefied carbon dioxide at that point.

[0048] The control device 1 opens the first control valve 3 to start injecting the liquefied carbon dioxide into the ground (step S101). Pressure is applied to the liquefied carbon dioxide by the injection pump 2, and the liquefied carbon dioxide is injected into the ground.

[0049] The control device 1 increases the opening of the first control valve 3 until the measured flow rate F1 of liquefied carbon dioxide measured by the first flow meter SR1 exceeds the preset planned flow rate F0 of liquefied carbon dioxide (steps S102 and S103). As long as the opening of the first control valve 3 does not reach its maximum, the control device 1 repeats this procedure to maintain the measured flow rate F1 exceeding the planned flow rate F0 (No in step S104).

[0050] When the measured flow rate F1 does not exceed the planned flow rate F0 and the aperture of the first control valve 3 reaches its maximum, the control device 1 opens the second control valve 7 to start pumping groundwater (Yes in step S104, step S105). The control device 1 increases the aperture of the second control valve 7 until the liquid flow rate F2 contained in the groundwater measured by the second flow meter SR2 exceeds the measured flow rate F1. Pumping the groundwater makes it easier to inject liquefied carbon dioxide underground. Furthermore, by making the liquid flow rate F2 equal to or greater than the measured flow rate F1, the groundwater is pumped so as to continue to secure space for storing the injected liquefied carbon dioxide.

[0051] The control device 1 increases the opening of the second control valve 7 until the measured flow rate F1 exceeds the planned flow rate F0 (steps S106 and S107). As long as the opening of the second control valve 7 does not reach its maximum, the control device 1 repeats this procedure to maintain the measured flow rate F1 exceeding the planned flow rate F0 (No in step S108).

[0052] When the measured flow rate F1 does not exceed the planned flow rate F0 and the opening of the second control valve 7 reaches its maximum, the control device 1 determines whether to continue injecting liquefied carbon dioxide based on the measured flow rate F1 (step S109). If the measured flow rate F1 exceeds a preset minimum flow rate, the control device 1 continues injecting liquefied carbon dioxide; if not, the control device 1 stops injecting liquefied carbon dioxide (steps S109, S110). The minimum flow rate is the lowest flow rate at which it is determined that even some liquefied carbon dioxide is being injected. The minimum flow rate may be a flow rate that is substantially zero. As a result, even if the measured flow rate F1 does not exceed the planned flow rate F0, the control device 1 continues injecting liquefied carbon dioxide as long as the measured flow rate F1 exceeds the minimum flow rate.

[0053] According to this embodiment, it is possible to facilitate underground storage of liquefied carbon dioxide. For example, if the measured flow rate F1 of the liquefied carbon dioxide being injected does not exceed the scheduled planned flow rate F0, it is possible to facilitate underground injection of the liquefied carbon dioxide by pumping up groundwater.

[0054] It is to be understood that additional advantages and modifications may readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents. [Explanation of symbols]

[0055] 1...control device, 2...injection pump, 3...first control valve, 4...injection blowout preventer, 5...pumping blowout preventer, 6...gas separator, 7...second control valve, 8...liquid buffer tank, 9...separated liquid tank, 10...third control valve, 11...separated gas tank, 20...carbon dioxide storage device, P1, P2, P3...piping, SR1, SR2, SR3...flow meter, SR4...water level sensor.

Claims

1. an injection pipe for injecting liquefied carbon dioxide from above ground into the ground; an injection pump for injecting liquefied carbon dioxide into the injection pipe; a first control valve for adjusting the flow rate of the liquefied carbon dioxide flowing through the injection pipe; a first flow meter that measures a flow rate of the liquefied carbon dioxide flowing through the injection pipe; a pumping pipe for pumping groundwater from the underground to the surface; a second control valve for adjusting the flow rate of the groundwater flowing through the pumping pipe; a second flow meter that measures the flow rate of the liquid contained in the groundwater flowing through the pumping pipe; a control unit that controls the second control valve so that the flow rate of the liquid measured by the second flow meter increases when the flow rate of the liquefied carbon dioxide measured by the first flow meter falls below a predetermined threshold; A carbon dioxide storage device comprising:

2. the control unit controls the second control valve so that the flow rate of the liquid measured by the second flow meter is equal to or greater than the flow rate of the liquefied carbon dioxide measured by the first flow meter. The carbon dioxide storage device according to claim 1 .

3. a gas separator for separating gas contained in the groundwater flowing through the pumping pipe; The carbon dioxide retention device according to claim 1, further comprising:

4. The second flow meter measures the flow rate of the liquid contained in the groundwater from which the gas has been separated by the gas separator. The carbon dioxide storage device according to claim 3,

5. a separated gas tank for storing the gas separated by the gas separator; The carbon dioxide storage device according to claim 3, further comprising:

6. a separation tank for separating gas and sediment from the groundwater flowing in the pumping pipe; The carbon dioxide retention device according to claim 1, further comprising:

7. The second flow meter measures the flow rate of the liquid from which the gas and the sediment have been separated from the groundwater by the separation tank. The carbon dioxide storage device according to claim 6,

8. a gas separator that separates gas contained in the groundwater flowing through the pumping pipe; a separated gas tank that stores the gas separated by the gas separator; a sensor for detecting the amount of the gas separated by the separation tank; a gas pipe through which the gas separated by the gas separator flows to the separated gas tank; a third control valve provided in the gas piping; a third flow meter that measures the flow rate of the gas flowing through the gas pipe; The control unit controls the third control valve based on the detection result by the sensor and the flow rate of the gas measured by the third flow meter so as to allow the gas separated by the gas separator to flow into the separated gas tank. The carbon dioxide storage device according to claim 6,

9. The control unit closes the first control valve and the second control valve urgently when it determines that the flow rate of the gas measured by the third flow meter has increased suddenly. The carbon dioxide storage device according to claim 8,

10. Injecting liquefied carbon dioxide into an injection pipe for injecting liquefied carbon dioxide from above ground into the ground; adjusting the flow rate of the liquefied carbon dioxide flowing through the injection pipe; measuring a flow rate of the liquefied carbon dioxide flowing through the injection pipe; adjusting the flow rate of groundwater flowing through a pumping pipe for pumping groundwater from the underground to the surface; measuring the flow rate of the liquid contained in the groundwater flowing through the pumping pipe; If the measured flow rate of the liquefied carbon dioxide falls below a predetermined threshold, adjusting the flow rate of the groundwater flowing through the pumping pipe so that the measured flow rate of the liquid increases. A carbon dioxide storage method comprising:

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