Carbon dioxide emission reduction method and carbon dioxide emission reduction system

Abstract

Exhaust G discharged from an internal combustion engine 20 is injected into an alkaline solution A stored in a storage tank 2, the alkaline solution A and the exhaust G are brought into contact with each other inside the storage tank 2, and the alkaline solution A and the carbon dioxide contained in the exhaust G are subjected to a neutralizing reaction. This reduces the amount of carbon dioxide contained in the exhaust G discharged from the internal combustion engine 20, and the exhaust G with the reduced amount of carbon dioxide is discharged from an exhaust port 2c of the storage tank 2. This can effectively reduce the amount of carbon dioxide contained in the exhaust G discharged from the internal combustion engine 20.

Description

Carbon dioxide emission reduction method and carbon dioxide emission reduction system

[0001] The present invention relates to a method and system for reducing carbon dioxide emissions, and more particularly to a method and system for reducing carbon dioxide emissions that can effectively reduce the carbon dioxide contained in exhaust gas emitted from an internal combustion engine.

[0002] In order to curb global warming, reducing carbon dioxide (CO2) emissions in construction work has become an important issue. Carbon dioxide emissions from internal combustion engines such as generators and diesel engines used in construction account for a relatively large proportion of carbon dioxide emissions in construction work. Therefore, it is important to reduce the carbon dioxide contained in the exhaust emitted from internal combustion engines in construction work.

[0003] Conventionally, urea SCR systems have been used to purify exhaust gas from internal combustion engines in automobiles and ships. However, urea SRC systems have been used to purify nitrogen oxides (NO X ) and cannot reduce the carbon dioxide contained in the exhaust gas (see, for example, Patent Document 1).

[0004] Japanese Patent Application Publication No. 2012-240446

[0005] An object of the present invention is to provide a method and system for reducing carbon dioxide emissions that can effectively reduce the amount of carbon dioxide contained in exhaust gas emitted from an internal combustion engine.

[0006] In order to achieve the above object, the method for reducing carbon dioxide emissions of the present invention is characterized in that exhaust gas emitted from an internal combustion engine is injected into an alkaline solution stored in a storage tank, the alkaline solution is brought into contact with the exhaust gas inside the storage tank, and a neutralization reaction occurs between the alkaline solution and the carbon dioxide contained in the exhaust gas, thereby reducing the carbon dioxide contained in the exhaust gas, and the exhaust gas with the reduced carbon dioxide content is discharged from an exhaust port of the storage tank.

[0007] In order to achieve the above-mentioned object, the carbon dioxide emission reduction system of the present invention comprises a storage tank in which an alkaline solution is stored, and an injection means for injecting exhaust gas emitted from an internal combustion engine into the alkaline solution stored in the storage tank, wherein the alkaline solution comes into contact with the exhaust gas injected by the injection means inside the storage tank, causing a neutralization reaction between the alkaline solution and the carbon dioxide contained in the exhaust gas, thereby reducing the carbon dioxide contained in the exhaust gas, and the exhaust gas with the reduced carbon dioxide content is discharged from an exhaust port of the storage tank.

[0008] According to the present invention, the carbon dioxide contained in the exhaust gas emitted from an internal combustion engine can be effectively reduced by injecting the exhaust gas into an alkaline solution stored in a storage tank and causing a neutralization reaction between the carbon dioxide contained in the exhaust gas and the alkaline solution inside the storage tank. Furthermore, the alkaline solution used to reduce the carbon dioxide contained in the exhaust gas can reduce its hydrogen ion concentration by causing a neutralization reaction with carbon dioxide. Therefore, the alkaline solution can be easily disposed of after use.

[0009] FIG. 1 is an explanatory diagram schematically illustrating an embodiment of a carbon dioxide emission reduction system of the present invention. FIG. 2 is an explanatory diagram schematically illustrating a cross-sectional view of the storage tank of FIG. 1. FIG. 3 is an explanatory diagram schematically illustrating a plurality of storage tanks and a notch tank connected in series that constitute a carbon dioxide emission reduction system of the present invention. FIG. 4 is an explanatory diagram schematically illustrating an exhaust gas supply line that constitutes a carbon dioxide emission reduction system of the present invention. FIG. 5 is an explanatory diagram schematically illustrating a solution supply line that constitutes a carbon dioxide emission reduction system of the present invention. FIG. 6 is a graph illustrating the progress of the hydrogen ion concentration of an alkaline solution in a carbon dioxide emission reduction system of the present invention and the progress of the cumulative amount of carbon dioxide absorbed from exhaust gas. FIG. 7 is an explanatory diagram schematically illustrating another embodiment of a carbon dioxide emission reduction system of the present invention. FIG. 8 is an explanatory diagram schematically illustrating yet another embodiment of a carbon dioxide emission reduction system of the present invention. FIG. 9 is an explanatory diagram schematically illustrating yet another embodiment of a carbon dioxide emission reduction system of the present invention.

[0010] Hereinafter, a carbon dioxide emission reduction method and a carbon dioxide emission reduction system according to the present invention will be described based on embodiments shown in the drawings.

[0011] The carbon dioxide emission reduction method and carbon dioxide emission reduction system 1 of the present invention, illustrated in Figures 1 to 5, reduce carbon dioxide (CO2) contained in exhaust G emitted from an internal combustion engine 20. Examples of the internal combustion engine 20 include a generator and a diesel engine. The carbon dioxide emission reduction system 1 of the present invention (hereinafter referred to as reduction system 1) can be applied to internal combustion engines 20 such as generators used in land-based construction work and diesel engines equipped in construction machinery. This reduction system 1 can also be applied to internal combustion engines 20 such as generators and diesel engines equipped in work vessels used in offshore construction work.

[0012] 1 , the reduction system 1 includes a storage tank 2 in which an alkaline solution A is stored, and an injection means 3 that injects exhaust gas G emitted from an internal combustion engine 20 into the alkaline solution A stored in the storage tank 2. In this reduction system 1, the alkaline solution A comes into contact with the exhaust gas G injected by the injection means 3 inside the storage tank 2, and a neutralization reaction occurs between the alkaline solution A and the carbon dioxide contained in the exhaust gas G, thereby reducing the carbon dioxide contained in the exhaust gas G. The exhaust gas G with reduced carbon dioxide is then discharged from an exhaust port 2c of the storage tank 2. In the figure, the flow of the exhaust gas G is schematically indicated by open arrows, and the flow of the alkaline solution A is schematically indicated by filled arrows.

[0013] Various solutions can be used as the alkaline solution A, as long as they are alkaline with a hydrogen ion concentration greater than pH 7 and undergo a neutralization reaction with carbon dioxide. Specifically, for example, calcium hydroxide solution or sodium hydroxide solution can be used as the alkaline solution A. It is preferable to use an alkaline solution A having a hydrogen ion concentration of, for example, pH 8 or higher and 14 or lower, preferably pH 9 or higher and 14 or lower, and more preferably pH 10 or higher and 14 or lower. In this embodiment, an example is shown in which the alkaline solution A (calcium hydroxide solution) is produced using recycled crushed stone R obtained by crushing concrete waste generated in demolition work, etc.

[0014] As shown in Fig. 1, the storage tank 2 is an airtight, hollow container. The storage tank 2 in this embodiment has a cylindrical portion extending in the vertical direction, and a tapered portion tapering downward below the cylindrical portion. The shape of the storage tank 2 is not limited to the shape in this embodiment, and a polygonal cylindrical storage tank 2 may also be used.

[0015] An inlet 2a through which the alkaline solution A flows is provided at the bottom of the storage tank 2, and a connecting pipe 6 is connected to the inlet 2a. A drain outlet 2d through which the alkaline solution A is discharged is provided at the top of the storage tank 2, and a connecting pipe 6 is connected to the drain outlet 2d. The drain outlet 2d is located near the liquid level of the alkaline solution A stored in the storage tank 2. The alkaline solution A flows into the inside of the storage tank 2 from a solution supply line (described later) through the connecting pipe 6 connected to the inlet 2a of the storage tank 2 (2X), and the alkaline solution A stored near the liquid level in the storage tank 2 flows out into the connecting pipe 6 connected to the drain outlet 2d.

[0016] In this embodiment, the injection means 3 includes an injection port 2b provided at the bottom of the storage tank 2, and an air vent pipe 5 inserted into the injection port 2b. An injection unit 4 is connected to the tip of the air vent pipe 5. The injection unit 4 is disposed at the bottom inside the storage tank 2. An exhaust port 2c through which exhaust gas G is discharged is provided at the top of the storage tank 2, and the air vent pipe 5 is connected to the exhaust port 2c. The exhaust port 2c is located above the liquid level of the alkaline solution A stored in the storage tank 2.

[0017] The exhaust gas G discharged from the internal combustion engine 20 is supplied to the injection unit 4 through an exhaust gas supply line (described later) and a vent pipe 5 inserted into the injection port 2b, and the supplied exhaust gas G is injected into the alkaline solution A by the injection unit 4. Then, the exhaust gas G injected from the injection unit 4 and passed through the alkaline solution A is discharged from the vent pipe 5 connected to the exhaust port 2c.

[0018] As illustrated in FIG. 2 , the injection unit 4 of this embodiment is configured to include multiple ejection nozzles 4 a and a branch pipe section 4 b. The branch pipe section 4 b is connected to the tip of the vent pipe 5 inserted into the injection port 2 b. Multiple ejection nozzles 4 a are disposed in the branch pipe section 4 b. Exhaust gas G supplied from the vent pipe 5 to the branch pipe section 4 b is distributed by the branch pipe section 4 b to each ejection nozzle 4 a, and the exhaust gas G is ejected from each ejection nozzle 4 a. The ejection of exhaust gas G from each ejection nozzle 4 a generates a swirling flow in the alkaline solution A inside the storage tank 2, causing numerous bubbles of exhaust gas G to rise in a spiral shape. In FIGS. 1 and 3 , the bubbles of exhaust gas G ejected from one ejection nozzle 4 a are shown relatively large for illustrative purposes, but in reality, numerous small bubbles of exhaust gas G are ejected from each ejection nozzle 4 a, resulting in a very large number of bubbles of exhaust gas G being ejected into the alkaline solution A.

[0019] More specifically, in this embodiment, the branch pipe section 4b has a connecting section in the center in a plan view that is connected to the tip of the vent pipe 5. The branch pipe section 4b further has multiple distribution pipes that branch out radially from the connecting section located in the center, and annular pipes located outside each distribution pipe and to which the outer ends of each distribution pipe are connected. Multiple ejection nozzles 4a are arranged at equal intervals around the circumferential direction of the annular pipe. In this embodiment, each ejection nozzle 4a is installed so as to eject exhaust gas G obliquely upward toward the inner surface of the storage tank 2. The number, arrangement, and ejection direction of the ejection nozzles 4a that make up the injection unit 4, as well as the shape of the branch pipe section 4b, are not limited to this embodiment and various other configurations are possible.

[0020] 1 , a discharge pipe 11 is connected to the bottom of the storage tank 2, and discharges a precipitate S generated by a neutralization reaction between carbon dioxide contained in the exhaust gas G and the alkaline solution A. The discharge pipe 11 is provided with an openable and closable discharge valve 12. In this embodiment, calcium carbonate generated by a neutralization reaction between carbon dioxide contained in the exhaust gas G and the alkaline solution A (aqueous calcium hydroxide solution) is deposited as precipitate S at the bottom of the storage tank 2.

[0021] The storage tank 2 is provided with a hydrogen ion concentration meter 13 that measures the hydrogen ion concentration of the stored alkaline solution A, and a carbon dioxide concentration meter 14 that measures the carbon dioxide concentration of the exhaust gas G after it has passed through the alkaline solution A in the storage tank 2. Furthermore, a pressure meter 15 that measures the pressure of the exhaust gas G that flows into the vent pipe 5 connected to the exhaust port 2c of the storage tank 2 is also provided. The hydrogen ion concentration meter 13, the carbon dioxide concentration meter 14, and the pressure meter 15 are each communicatively connected to a management device 40, an example of which is shown in FIG. 3 . The management device 40 is comprised of a computer. The measurement data measured by the hydrogen ion concentration meter 13, the carbon dioxide concentration meter 14, and the pressure meter 15 are transmitted to the management device 40 as needed, and the transmitted measurement data is displayed on the monitor of the management device 40.

[0022] 3, in this embodiment, three storage tanks 2 (2X to 2Z) are connected in series via a vent pipe 5 through which exhaust gas G flows and a connecting pipe 6 through which alkaline solution A flows. The structure of each of the storage tanks 2X to 2Z and the configuration of the injection means 3 provided in each of the storage tanks 2X to 2Z are the same. Each of the storage tanks 2X to 2Z is ​​provided with a hydrogen ion concentration meter 13, a carbon dioxide concentration measuring instrument 14, and a pressure gauge 15, and the measurement data from each of these is transmitted to the management device 40 as needed.

[0023] The downstream end of the vent pipe 5 connected to the exhaust port 2c of the upstream storage tank 2X (on the internal combustion engine 20 side) is connected to an injection unit 4 provided in the downstream storage tank 2Y. The downstream end of the connecting pipe 6 connected to the drain port 2d of the upstream storage tank 2X is connected to the inlet 2a of the downstream storage tank 2Y. The downstream end of the vent pipe 5 connected to the exhaust port 2c of the storage tank 2Y is connected to an injection unit 4 provided in the downstream storage tank 2Z. The downstream end of the connecting pipe 6 connected to the drain port 2d of the storage tank 2Y is connected to the inlet 2a of the downstream storage tank 2Z.

[0024] An exhaust pipe 7 is connected to the exhaust port 2c of the most downstream storage tank 2Z, and the exhaust G discharged from the exhaust port 2c of the storage tank 2Z is ​​discharged to the atmosphere via the exhaust pipe 7 as treated exhaust GP with reduced carbon dioxide. A connecting pipe 6 is connected to the drain port 2d of the most downstream storage tank 2Z, and the downstream end of the connecting pipe 6 is connected to the upstream inlet of the notch tank 17. The alkaline solution A that flows into the notch tank 17 is discharged from a drain pipe 9 connected to the downstream outlet of the notch tank 17 as a neutralized treated solution AP.

[0025] 4 , in an exhaust supply line that supplies exhaust G discharged from an internal combustion engine 20 to the injection means 3, a manifold 21 is connected downstream of the internal combustion engine 20 via a vent pipe 5. The exhaust G discharged from the internal combustion engine 20 flows into the manifold 21 through the vent pipe 5. In this embodiment, a plurality of internal combustion engines 20 are connected to the manifold 21 via their respective vent pipes 5, and the exhaust G discharged from the plurality of internal combustion engines 20 is collected in the manifold 21.

[0026] A dust collector 22 is connected to the downstream side of the manifold 21 via an air vent pipe 5. The dust collector 22 is a device that removes dust contained in the exhaust gas G. A pressure-feeding device 24 is connected to the downstream side of the dust collector 22 via an air vent pipe 5. A heat removal tank 23 that removes heat from the exhaust gas G is provided between the dust collector 22 and the pressure-feeding device 24.

[0027] Cooling water CW is stored in the heat removal tank 23, and a midpoint of the vent pipe 5 connecting the dust collector 22 and the pumping device 24 is submerged in the cooling water CW stored in the heat removal tank 23. A supply pipe for supplying new cooling water CW to the heat removal tank 23 and a drain pipe for discharging the cooling water CW stored in the heat removal tank 23 are connected to the heat removal tank 23, and by replacing the cooling water CW, the temperature of the cooling water CW stored in the heat removal tank 23 is maintained at or below a predetermined temperature.

[0028] The exhaust gas G discharged from the dust collector 22 has its heat removed in the heat removal tank 23, and then passes through the vent pipe 5 and is sucked into the pressure-feeding device 24. The pressure-feeding device 24 is a device that pumps the exhaust gas G to the injection means 3, and is composed of a gas pump such as a vacuum pump. The injection unit 4 is connected downstream of the pressure-feeding device 24 via the vent pipe 5, and the exhaust gas G pumped by the pressure-feeding device 24 is supplied to the injection unit 4.

[0029] As shown in Figure 5, a solution supply line that supplies alkaline solution A to the storage tank 2 has a solution generation tank 30 that generates alkaline solution A provided upstream. In this embodiment, water W is supplied to the solution generation tank 30, and recycled crushed stone R is added at predetermined time intervals. A stirrer 31 is provided in the solution generation tank 30. An outlet is provided at the top of the solution generation tank 30 from which the generated alkaline solution A flows out. An outlet is provided at the bottom of the solution generation tank 30 from which the treated recycled crushed stone RP that has been used to generate the alkaline solution A and neutralized is discharged.

[0030] A raw water level adjustment tank 32 is provided downstream of the solution production tank 30 to temporarily store the alkaline solution A produced in the solution production tank 30. The outlet of the solution production tank 30 and the raw water level adjustment tank 32 are connected by a connecting pipe 6, and the alkaline solution A produced in the solution production tank 30 flows into the raw water level adjustment tank 32 through the connecting pipe 6.

[0031] A hydrogen ion concentration meter 13 is provided in the raw water level adjustment tank 32, and measurement data of the hydrogen ion concentration measured by the hydrogen ion concentration meter 13 is transmitted as needed to the management device 40. An outlet through which the alkaline solution A flows out is provided at the top of the raw water level adjustment tank 32. A storage tank 2X is provided downstream of the raw water level adjustment tank 32, and the outlet of the raw water level adjustment tank 32 and the inlet 2a of the storage tank 2X are connected by a connecting pipe 6. The outlet of the raw water level adjustment tank 32 is positioned higher than the inlet 2a of the storage tank 2X.

[0032] The liquid level of the alkaline solution A stored in the raw water level adjustment tank 32, the liquid level of the alkaline solution A stored in each of the storage tanks 2X to 2Z, and the liquid level of the alkaline solution A stored in the notch tank 17 are set to the same height.

[0033] Next, a carbon dioxide emission reduction method using this reduction system 1 will be described.

[0034] As shown in FIG. 5, in the solution supply line, water W is supplied to the solution generation tank 30 and recycled crushed stone R is introduced. The recycled crushed stone R accumulates at the bottom of the solution generation tank 30. The water W supplied to the solution generation tank 30 can be seawater, river water, groundwater, tap water, or the like at the construction site. When the water W stored in the solution generation tank 30 is stirred by the agitator 31, the calcium hydroxide contained in the recycled crushed stone R dissolves in the water W, and an alkaline solution A (calcium hydroxide solution) is generated. When the calcium hydroxide contained in the recycled crushed stone R dissolves in the water W, the recycled crushed stone R accumulated at the bottom of the solution generation tank 30 is neutralized. The treated recycled crushed stone RP used to generate the alkaline solution A and neutralized is discharged and collected from a discharge outlet provided at the bottom of the solution generation tank 30.

[0035] The alkaline solution A generated in the solution generation tank 30 flows into the raw water level adjustment tank 32 through a connecting pipe 6 connected to the outlet of the solution generation tank 30 and is stored in the raw water level adjustment tank 32. In the raw water level adjustment tank 32, the hydrogen ion concentration of the stored alkaline solution A is measured using a hydrogen ion concentration meter 13, and the amount of recycled crushed stone R added to the solution generation tank 30 is adjusted based on the measurement results. The amount of recycled crushed stone R added to the solution generation tank 30 can be adjusted so that the hydrogen ion concentration of the alkaline solution A stored in the raw water level adjustment tank 32 is, for example, pH 8 to 14, preferably pH 9 to 14, and more preferably pH 10 to 14. The alkaline solution A stored in the raw water level adjustment tank 32 flows into the storage tank 2X through the inlet 2a of the storage tank 2X through the connecting pipe 6 connected to the outlet of the raw water level adjustment tank 32. In the solution generation tank 30, the flow rate of the alkaline solution A supplied to the raw water level adjustment tank 32 is adjusted so as to maintain the liquid surface position of the alkaline solution A stored in the raw water level adjustment tank 32 at a predetermined height.

[0036] 4 , in the exhaust supply line, when the target internal combustion engines 20 are operating, the exhaust G emitted from each internal combustion engine 20 flows into the manifold 21 through the ventilation pipe 5. The exhaust G collected in the manifold 21 flows into the dust collector 22 through the ventilation pipe 5, and dust contained in the exhaust G is removed by the dust collector 22.

[0037] The exhaust gas G from which dust has been removed by the dust collector 22 passes through a vent pipe 5 submerged in cooling water CW stored in a heat removal tank 23, where heat is removed, and the heat-removed exhaust gas G is taken into a pressure-feeding device 24. Seawater, river water, groundwater, tap water, industrial water, etc. at the construction site can be used as the cooling water CW in the heat removal tank 23. The exhaust gas G taken into the pressure-feeding device 24 is pressure-fed by the pressure-feeding device 24 to an injection means 3 provided in the storage tank 2X.

[0038] 1 to 3, in the storage tank 2X, the exhaust gas G pumped by the pumping device 24 is injected into the alkaline solution A stored in the storage tank 2X by the injection means 3. In this embodiment, the exhaust gas G pumped by the pumping device 24 flows into the branch pipe section 4b of the injection unit 4, and the exhaust gas G that has flowed into the branch pipe section 4b is ejected from each ejection nozzle 4a. As the exhaust gas G is ejected from each ejection nozzle 4a, a swirling flow is generated in the alkaline solution A inside the storage tank 2X, causing a large number of bubbles of the exhaust gas G to rise in a spiral shape.

[0039] As the bubbles of exhaust gas G spiral upward through alkaline solution A, they come into contact with the exhaust gas G, causing a neutralization reaction between the alkaline solution A and the carbon dioxide contained in the exhaust gas G. Specifically, when a calcium hydroxide solution is used as alkaline solution A, the carbon dioxide (CO2) contained in the exhaust gas G reacts chemically with the water (H2O) contained in the calcium hydroxide solution to produce carbon dioxide (H2CO3) (CO2 + H2O → H2CO3). The produced carbon dioxide (H2CO3) then reacts chemically with calcium hydroxide (Ca(OH)2) contained in the calcium hydroxide solution to produce calcium carbonate (CaCO3) (Ca(OH)2 + H2CO3 → CaCO3 + 2H2O).

[0040] The carbon dioxide contained in the exhaust gas G is reduced by a neutralization reaction between the carbon dioxide contained in the exhaust gas G and the alkaline solution A. The exhaust gas G, whose carbon dioxide content has been reduced by passing through the alkaline solution A, accumulates in the upper part of the inside of the storage tank 2X. As illustrated in Figure 3, the exhaust gas G that has accumulated in the upper part of the inside of the storage tank 2X flows as needed through the vent pipe 5 connected to the exhaust port 2c of the storage tank 2X and into the injection means 3 provided in the downstream storage tank 2Y.

[0041] Fresh alkaline solution A is continuously supplied to inlet 2a of storage tank 2X via the solution supply line, and alkaline solution A, whose hydrogen ion concentration has decreased due to a neutralization reaction with carbon dioxide contained in exhaust gas G, rises within storage tank 2X together with exhaust gas G. Then, alkaline solution A that has risen to the top of storage tank 2X passes through connecting pipe 6 connected to drain outlet 2d and flows into storage tank 2Y from inlet 2a provided at the bottom of storage tank 2Y on the downstream side.

[0042] The precipitate S (calcium carbonate) produced by the neutralization reaction settles at the bottom of the storage tank 2X. The precipitate S accumulated at the bottom of the storage tank 2X is discharged to the outside of the storage tank 2X and collected by appropriately opening the discharge valve 12 of the discharge pipe 11 connected to the storage tank 2X.

[0043] The alkaline solution A, the hydrogen ion concentration of which has been reduced by the neutralization reaction in the upstream storage tank 2X, flows into the downstream storage tank 2Y. Exhaust gas G discharged from the exhaust port 2c of the upstream storage tank 2X flows into the branch pipe 4b of the injection unit 4 provided in the downstream storage tank 2Y, and the exhaust gas G that has flowed into the branch pipe 4b is ejected from each ejection nozzle 4a. As with the upstream storage tank 2X, the ejection of exhaust gas G from each ejection nozzle 4a generates a swirling flow in the alkaline solution A inside the downstream storage tank 2Y, causing many bubbles of exhaust gas G to rise in a spiral shape.

[0044] Then, as the bubbles of exhaust gas G spirally rise through alkaline solution A, the alkaline solution A comes into contact with the exhaust gas G, causing a neutralization reaction between the alkaline solution A and the carbon dioxide contained in the exhaust gas G. This neutralization reaction further reduces the carbon dioxide contained in the exhaust gas G, further lowering the hydrogen ion concentration of alkaline solution A. The exhaust gas G, whose carbon dioxide content has been further reduced after passing through alkaline solution A, accumulates in the upper part of the inside of storage tank 2Y. The exhaust gas G that has accumulated in the upper part of the inside of storage tank 2Y then flows as needed through vent pipe 5 connected to exhaust port 2c of storage tank 2Y into injection means 3 provided in storage tank 2Z further downstream.

[0045] As the alkaline solution A continues to flow into the inlet 2a of the storage tank 2Y, the alkaline solution A undergoes a neutralization reaction with the carbon dioxide contained in the exhaust gas G, further reducing the hydrogen ion concentration, and rises within the storage tank 2Y together with the exhaust gas G. The alkaline solution A that has risen to the top of the storage tank 2Y passes through the connecting pipe 6 connected to the drain outlet 2d and flows into the inside of the storage tank 2Z from the inlet 2a provided at the bottom of the storage tank 2Z on the downstream side.

[0046] The precipitate S produced by the neutralization reaction settles to the bottom of the storage tank 2Y. The precipitate S accumulated in the bottom of the storage tank 2Y is discharged to the outside of the storage tank 2Y and collected by appropriately opening the discharge valve 12 of the discharge pipe 11 connected to the storage tank 2Y.

[0047] The alkaline solution A, whose hydrogen ion concentration has been further reduced by the neutralization reaction in the storage tank 2Y, flows into and is stored in the storage tank 2Z on the most downstream side. Then, the exhaust gas G discharged from the exhaust port 2c of the storage tank 2Y flows into the branch pipe portion 4b of the injection unit 4 provided in the storage tank 2Z, and the exhaust gas G that has flowed into the branch pipe portion 4b is sprayed out from each spray nozzle 4a. Then, as in the storage tank 2Y, a swirling flow is generated inside the alkaline solution A in which many bubbles of the exhaust gas G rise in a spiral shape, and a neutralization reaction occurs between the alkaline solution A and the carbon dioxide contained in the exhaust gas G.

[0048] This neutralization reaction further reduces the carbon dioxide contained in the exhaust gas G, further decreasing the hydrogen ion concentration in the alkaline solution A. The exhaust gas G, which has passed through the alkaline solution A and has had its carbon dioxide content further reduced, accumulates in the upper part of the inside of the storage tank 2Z. The exhaust gas G that has accumulated in the upper part of the inside of the storage tank 2Z is ​​then discharged from the exhaust port 2c of the storage tank 2Z as needed, and is discharged into the atmosphere via the exhaust pipe 7 as treated exhaust gas GP with reduced carbon dioxide content.

[0049] As the alkaline solution A continues to flow into the inlet 2a of the storage tank 2Z, it undergoes a neutralization reaction with the carbon dioxide contained in the exhaust gas G, further reducing the hydrogen ion concentration of the alkaline solution A, which then rises within the storage tank 2Z together with the exhaust gas G. The alkaline solution A that has risen to the top of the storage tank 2Z then flows into the notch tank 17 through the connecting pipe 6 connected to the drain outlet 2d. The alkaline solution A that has flowed into the notch tank 17 has any remaining sediment removed therefrom, and is then discharged as a neutralized treated solution AP into public water bodies, a sewer, or the like.

[0050] The precipitate S produced by the neutralization reaction settles to the bottom of the storage tank 2Z. The precipitate S accumulated at the bottom of the storage tank 2Z is ​​discharged to the outside of the storage tank 2Z and collected by appropriately opening the discharge valve 12 of the discharge pipe 11 connected to the storage tank 2Z.

[0051] The measurement data measured by each of the hydrogen ion concentration meter 13, carbon dioxide concentration meter 14, and pressure meter 15 is transmitted to the management device 40 as needed and displayed on the monitor of the management device 40. The manager of the reduction system 1 can monitor the operating status of the reduction system 1 by checking the measurement data displayed on the monitor of the management device 40.

[0052] In the graph illustrated in Figure 6, the vertical axis on the left represents the hydrogen ion concentration (pH) of alkaline solution A, and the vertical axis on the right represents the cumulative absorption amount of carbon dioxide contained in exhaust gas G. M0 on the horizontal axis of the graph represents the hydrogen ion concentration of alkaline solution A stored in raw water level adjustment tank 32. M1 represents the hydrogen ion concentration of alkaline solution A stored in storage tank 2X and the cumulative absorption amount of carbon dioxide absorbed in storage tank 2X. M2 represents the hydrogen ion concentration of alkaline solution A stored in storage tank 2Y and the cumulative absorption amount of carbon dioxide absorbed in storage tanks 2X and 2Y. M3 represents the hydrogen ion concentration of alkaline solution A stored in storage tank 2Z and the cumulative absorption amount of carbon dioxide absorbed in storage tanks 2X to 2Z. In Figure 6, the dashed line indicates the change in the hydrogen ion concentration of alkaline solution A, and the solid line indicates the change in the cumulative absorption amount of carbon dioxide.

[0053] 6, a neutralization reaction occurs between the alkaline solution A and the carbon dioxide contained in the exhaust gas G in each of the storage tanks 2X to 2Z, causing an increase in the cumulative absorption amount of carbon dioxide contained in the exhaust gas G and a decrease in the hydrogen ion concentration of the alkaline solution A. In the upstream storage tank 2X, the hydrogen ion concentration of the alkaline solution A is relatively high, and the proportion of carbon dioxide contained in the exhaust gas is also relatively high, so the neutralization reaction between the alkaline solution A and the carbon dioxide contained in the exhaust gas G proceeds relatively actively, resulting in a relatively large amount of carbon dioxide being absorbed from the exhaust gas G. The hydrogen ion concentration of the alkaline solution A also decreases relatively significantly.

[0054] In the downstream storage tanks 2Y and 2Z, the proportion of carbon dioxide contained in the exhaust gas G and the hydrogen ion concentration of the alkaline solution A gradually decrease, so that the amount of carbon dioxide absorbed from the exhaust gas G gradually decreases compared to the upstream storage tank 2X, but by the time the exhaust gas G is finally released as treated exhaust gas GP, most of the carbon dioxide contained in the exhaust gas G has been absorbed by the neutralization reaction. Also, by the time the alkaline solution A is finally processed into treated solution AP, the neutralization process is complete and the hydrogen ion concentration becomes close to neutral.

[0055] As described above, according to the present invention, the carbon dioxide contained in the exhaust G discharged from the internal combustion engine 20 can be effectively reduced by injecting the exhaust G discharged from the internal combustion engine 20 into the alkaline solution A stored in the storage tank 2 and causing a neutralization reaction between the carbon dioxide contained in the exhaust G and the alkaline solution A inside the storage tank 2. This contributes to reducing emissions of carbon dioxide, a greenhouse gas that contributes to global warming. Furthermore, the alkaline solution A used to reduce the carbon dioxide contained in the exhaust G can have a lower hydrogen ion concentration by causing a neutralization reaction with carbon dioxide. Therefore, the alkaline solution A can be easily disposed of after use.

[0056] Construction work generates a large amount of alkaline wastewater with a relatively high hydrogen ion concentration. For example, demolition work generates a large amount of concrete waste, and the recycled crushed stone obtained by crushing this concrete waste is alkaline like concrete. Therefore, a large amount of alkaline wastewater is generated when neutralized recycled crushed stone is produced. In addition, construction work generates a large amount of alkaline wastewater (so-called cleaning water or wash water) during cleaning operations of cement, mortar, and concrete manufacturing plants and transportation equipment.

[0057] When disposing of alkaline wastewater generated during construction work, it is necessary to perform a neutralization process to adjust the hydrogen ion concentration of the alkaline wastewater to a pH of 5.8 to 8.6 or less. Neutralization is generally performed by adding an acidic neutralizing agent to the alkaline wastewater. This reduction system 1 utilizes alkaline wastewater generated during construction work as alkaline solution A, thereby reducing the carbon dioxide contained in the exhaust G of the internal combustion engine 20 and neutralizing the alkaline wastewater.

[0058] Carbon dioxide emissions from internal combustion engines 20 such as generators and diesel engines account for a large proportion of carbon dioxide emissions in construction work, and construction work generates a large amount of alkaline wastewater. Therefore, the reduction system 1 of the present invention, which can effectively utilize the alkaline wastewater generated in construction work to reduce carbon dioxide emissions from the exhaust G of the internal combustion engines 20, is extremely useful for those skilled in the art of construction work.

[0059] In particular, as in this embodiment, by generating alkaline solution A using recycled crushed stone R obtained by crushing concrete waste and storing the generated alkaline solution A in the storage tank 2, the alkaline recycled crushed stone R can be effectively used to generate alkaline solution A while producing neutralized recycled crushed stone RP. If alkaline recycled crushed stone R is used as paving material, its use is limited due to the possibility of increasing the hydrogen ion concentration in the surrounding soil. In contrast, neutralized recycled crushed stone RP can be used in a wider range of applications. This allows for more effective use of concrete waste. Furthermore, by using the alkaline wastewater generated during the neutralization of recycled crushed stone R as alkaline solution A, carbon dioxide emissions from the exhaust G of the internal combustion engine 20 can be reduced and the alkaline wastewater can be neutralized. This is therefore extremely beneficial for those skilled in the art of construction work.

[0060] Even when alkaline wastewater generated in cleaning operations of cement, mortar, and concrete manufacturing plants or transport facilities is used as alkaline solution A, the alkaline wastewater can be effectively utilized as alkaline solution A to neutralize the alkaline wastewater while reducing the amount of carbon dioxide emitted by the exhaust G of the internal combustion engine 20. When alkaline wastewater generated in cleaning operations is used, it is preferable to previously mix and stir a coagulant into the alkaline wastewater to perform a coagulation treatment to remove coagulated solids, and then supply the alkaline wastewater after the coagulation treatment as alkaline solution A to the raw water level adjustment tank 32 or the storage tank 2.

[0061] Construction sites often have excess cement and lime, and the reduction system 1 can be configured to use such excess cement and lime to generate the alkaline solution A. The reduction system 1 can also be configured to generate the alkaline solution A using slag generated during metal smelting.

[0062] In this way, the carbon dioxide emission reduction system 1 of the present invention not only reduces the carbon dioxide emissions from the exhaust G of the internal combustion engine 20, but also functions as a system for neutralizing alkaline wastewater and alkaline waste materials generated during construction work. Therefore, this reduction system 1 is very useful for those skilled in the art of construction work.

[0063] In this embodiment, a plurality of ejection nozzles 4a are disposed at the bottom inside the storage tank 2, and exhaust gas G is ejected from each of the ejection nozzles 4a to generate a swirling flow in which numerous bubbles of exhaust gas G rise in a spiral shape into the alkaline solution A. With this configuration, the travel distance and time required for the bubbles of exhaust gas G to pass through the alkaline solution A can be secured longer than in the case where the bubbles of exhaust gas G are caused to rise straight up in the alkaline solution A. Therefore, the carbon dioxide contained in the exhaust gas G can be more effectively neutralized in the storage tank 2 with the alkaline solution A.

[0064] Furthermore, the longer the vertical distance between the position where the exhaust gas G is ejected by the injection means 3 and the liquid surface of the alkaline solution A stored in the storage tank 2, the longer the travel distance and the time required for the bubbles of the exhaust gas G to pass through the alkaline solution A can be secured, but on the other hand, the higher the pumping pressure required to inject the exhaust gas G into the alkaline solution A. The higher the pumping pressure of the exhaust gas G, the more power the pumping device 24 will consume, and the more carbon dioxide will be emitted by the generator that supplies power to the pumping device 24.

[0065] In this regard, by using a configuration in which a swirling flow is generated in which a large number of exhaust gas G bubbles rise in a spiral shape in the alkaline solution A, as in this embodiment, it is possible to relatively shorten the vertical distance between the position where the exhaust gas G is ejected by the injection means 3 and the liquid surface of the alkaline solution A, while ensuring a long travel distance and time required for the exhaust gas G bubbles to pass through the alkaline solution A. This makes it possible to set the pumping pressure of the exhaust gas G by the pumping device 24 relatively low, which is also advantageous for reducing the power consumption of the pumping device 24. This is therefore more advantageous for reducing carbon dioxide emissions.

[0066] In this embodiment, when multiple storage tanks 2 (2X to 2Z) are connected in series via a vent pipe 5 through which exhaust gas G flows and a connecting pipe 6 through which alkaline solution A flows, the exhaust gas G is passed through the alkaline solution A stored in the multiple storage tanks 2, which allows the carbon dioxide contained in the exhaust gas G to undergo a neutralization reaction more effectively with the alkaline solution A. This is therefore more advantageous for reducing the carbon dioxide contained in the exhaust gas G emitted from the internal combustion engine 20. Furthermore, by flowing the alkaline solution A together with the exhaust gas G from the upstream storage tank 2 to the downstream storage tank 2, the alkaline solution A can be utilized more effectively. Furthermore, by causing the alkaline solution A to undergo a neutralization reaction with the carbon dioxide contained in the exhaust gas G in each storage tank 2, this is also advantageous for accelerating the neutralization process of the alkaline solution A.

[0067] By aligning the liquid levels of the alkaline solution A stored in the raw water level adjustment tank 32 and each of the storage tanks 2 (2X-2Z) as in this embodiment, the alkaline solution A can be naturally caused to flow from the raw water level adjustment tank 32 to the most downstream storage tank 2Z by utilizing the siphon principle, without providing a power source such as a pump to the connecting pipe 6 connecting the raw water level adjustment tank 32 and the storage tank 2, or to the connecting pipes 6 connecting the storage tanks 2 together. This is therefore even more advantageous for reducing carbon dioxide emissions. Furthermore, despite the simple configuration, it is possible to maintain a constant amount of alkaline solution A stored in each of the storage tanks 2X-2Z.

[0068] The reduction system 1 of the present invention may also be configured as shown in FIG.

[0069] In this embodiment, separate exhaust pipes 7 are connected midway through the vent pipe 5 connecting the storage tank 2X and the storage tank 2Y, and midway through the vent pipe 5 connecting the storage tank 2Y and the storage tank 2Z. Each exhaust pipe 7 is provided with an openable / closeable exhaust valve 8. Separate drain pipes 9 are connected midway through the connecting pipe 6 connecting the storage tank 2X and the storage tank 2Y, and midway through the connecting pipe 6 connecting the storage tank 2Y and the storage tank 2Z. Each drain pipe 9 is provided with an openable / closeable drain valve 10. Furthermore, each of the storage tanks 2X and 2Y is provided with a control device 16. The control device 16 is, for example, configured by a computer.

[0070] The hydrogen ion concentration meter 13 and the carbon dioxide concentration meter 14 provided in the same storage tank 2 are each communicatively connected to a control device 16 provided in the same storage tank 2. The measurement data measured by the hydrogen ion concentration meter 13 and the carbon dioxide concentration meter 14 are input to the control device 16 as needed. In this embodiment, the opening and closing operations of the exhaust valves 8 and the drainage valves 10 are automatically controlled by the control devices 16 provided in the storage tanks 2 upstream of each valve. The remaining configuration is the same as that of the reduction system 1 of the embodiment illustrated in FIGS. 1 to 5.

[0071] In this embodiment, the hydrogen ion concentration of the alkaline solution A stored in each storage tank 2 is measured by a hydrogen ion concentration meter 13, and alkaline solution A whose hydrogen ion concentration is equal to or lower than a preset threshold is treated as treated solution AP without being allowed to flow into the downstream storage tank 2. The threshold value of the hydrogen ion concentration of the alkaline solution A described above is set to, for example, about pH 7.0 to pH 8.6.

[0072] Specifically, for example, when the hydrogen ion concentration of alkaline solution A measured by hydrogen ion concentration meter 13 provided in storage tank 2X is higher than a preset threshold, control device 16 provided in storage tank 2X controls drain valve 10 provided between storage tank 2X and downstream storage tank 2Y to close. Then, alkaline solution A that has flowed into connecting pipe 6 from drain port 2d of storage tank 2X passes through connecting pipe 6 as it is and flows into downstream storage tank 2Y.

[0073] On the other hand, when the hydrogen ion concentration of alkaline solution A measured by hydrogen ion concentration meter 13 provided in storage tank 2X is equal to or lower than a preset threshold, control device 16 provided in storage tank 2X controls drain valve 10 provided between storage tank 2X and downstream storage tank 2Y to be open. Then, alkaline solution A flowing from drain port 2d of storage tank 2X into connecting pipe 6 flows into drain pipe 9 halfway through connecting pipe 6, and the neutralized alkaline solution A flowing into drain pipe 9, whose hydrogen ion concentration is equal to or lower than the threshold, is discharged into a sewer or the like as treated solution AP.

[0074] When the drain valve 10 is opened and alkaline solution A is discharged from the drain pipe 9, the flow rate of the alkaline solution A stored in the storage tank 2 downstream of the drain pipe 9 temporarily decreases, but the alkaline solution A continues to be supplied from the solution generation tank 30, so that the liquid surface heights of the alkaline solution A stored in the raw water level adjustment tank 32 and each of the storage tanks 2X to 2Z are maintained at the same height.

[0075] With this configuration, alkaline solution A, whose hydrogen ion concentration has fallen below a preset threshold and whose carbon dioxide absorption rate has decreased, does not flow into the downstream storage tank 2 but is treated as treated solution AP. Therefore, even without finely adjusting the hydrogen ion concentration of alkaline solution A generated in the solution generation tank 30, fluctuations in the hydrogen ion concentration of alkaline solution A stored in each storage tank 2 can be reduced, and fluctuations in the amount of carbon dioxide absorbed in each storage tank 2 can be reduced. Therefore, this is more advantageous for stably reducing the carbon dioxide contained in the exhaust gas G, despite the simple control.

[0076] In this embodiment, the carbon dioxide concentration of the exhaust gas G after passing through the alkaline solution A in each storage tank 2 is measured by a carbon dioxide concentration measuring device 14, and the exhaust gas G whose carbon dioxide concentration is below a preset reference value is treated as treated exhaust gas GP without being injected into the alkaline solution A stored in the downstream storage tank 2. The reference value for the carbon dioxide concentration of the exhaust gas G mentioned above is set to, for example, about 5000 ppm.

[0077] Specifically, for example, when the carbon dioxide concentration of the exhaust gas G measured by the carbon dioxide concentration measuring device 14 provided in the storage tank 2X is higher than a preset reference value, the control device 16 provided in that storage tank 2X performs control to close the exhaust valve 8 provided between that storage tank 2X and the downstream storage tank 2Y. Then, the exhaust gas G that flows into the vent pipe 5 from the exhaust port 2c of the storage tank 2X passes through the vent pipe 5 as it is and flows into the injection means 3 provided in the downstream storage tank 2Y.

[0078] On the other hand, when the carbon dioxide concentration of the exhaust gas G measured by the carbon dioxide concentration measuring device 14 provided in the storage tank 2X is equal to or lower than a preset reference value, the control device 16 provided in that storage tank 2X controls the exhaust valve 8 provided between that storage tank 2X and the downstream storage tank 2Y to be in an open state. The exhaust gas G that flows into the vent pipe 5 from the exhaust port 2c of the storage tank 2X then flows into the exhaust pipe 7 midway through the vent pipe 5, and the exhaust gas G that has flowed into the exhaust pipe 7 and whose carbon dioxide concentration is equal to or lower than the reference value is released into the atmosphere as treated exhaust gas GP.

[0079] With this configuration, exhaust gas G whose carbon dioxide concentration is below a preset reference value and which hardly undergoes a neutralization reaction with alkaline solution A is not injected into the alkaline solution A stored in the downstream storage tank 2, but is treated as treated exhaust gas GP. This makes it possible to reduce fluctuations in the carbon dioxide concentration of the exhaust gas G injected into the alkaline solution A stored in each storage tank 2. This also makes it possible to reduce fluctuations in the hydrogen ion concentration of the alkaline solution A stored in each storage tank 2. This makes it possible to stably reduce the carbon dioxide contained in the exhaust gas G and stably neutralize the alkaline solution A, despite the simple control.

[0080] The reduction system 1 of the present invention may also be configured as shown in FIG.

[0081] In this embodiment, protrusions 2e are provided on the inner surface of the storage tank 2, and the protrusions 2e are used to slow the rising speed of the exhaust gas G bubbles rising in the alkaline solution A. In other words, the provision of protrusions 2e on the inner surface of the storage tank 2 to act as obstacles to the rising bubbles of the exhaust gas G increases the time the bubbles of the exhaust gas G remain in the alkaline solution A. In this embodiment, protrusions 2e extending in a spiral shape are provided on the inner surface of the storage tank 2, and the protrusions 2e are used to guide the swirling flow of the many exhaust gas G bubbles that rise in a spiral shape, which are generated by the injection means 3.

[0082] The other configurations are the same as those of the reduction system 1 of the embodiment illustrated in Figures 1 to 5. Note that the protrusion 2e is not limited to the spiral structure of this embodiment, and various other configurations are possible as long as the structure can slow down the rising speed of the exhaust gas bubbles G rising in the alkaline solution A.

[0083] In this way, by providing the protrusions 2e on the inner surface of the storage tank 2, the time that the bubbles of the exhaust gas G injected into the alkaline solution A from the injection means 3 come into contact with the alkaline solution A can be extended, and therefore the carbon dioxide contained in the exhaust gas G can be more effectively neutralized with the alkaline solution A within the storage tank 2. Therefore, despite the simple configuration, this is even more advantageous for reducing the carbon dioxide contained in the exhaust gas G.

[0084] As in this embodiment, when the protrusions 2e are configured to guide the swirling flow of the many bubbles of exhaust G generated by the injection means 3 rising in a spiral shape, the protrusions 2e make the swirling flow more stable, which is more advantageous in ensuring a longer distance and time for the bubbles of exhaust G to travel in the alkaline solution A. Therefore, the carbon dioxide contained in the exhaust G can be more effectively neutralized with the alkaline solution A in the storage tank 2, which is even more advantageous in reducing the carbon dioxide contained in the exhaust G.

[0085] The reduction system 1 of the present invention can also be configured as shown in FIG.

[0086] In this embodiment, the configuration of the injection means 3 is different. The other configuration is the same as that of the reduction system 1 of the embodiment illustrated in FIGS. 1 to 5. In this embodiment, the injection means 3 is composed of a plurality of jet nozzles 4a inserted laterally into the side wall of the storage tank 2. Four injection ports 2b are provided at equal intervals in the circumferential direction on the side wall of the storage tank 2, and an injection nozzle 4a is inserted into each injection port 2b. The exhaust gas G is ejected laterally from each jet nozzle 4a along the inner surface of the storage tank 2, thereby generating a swirling flow in which numerous bubbles of exhaust gas G rise spirally in the alkaline solution A inside the storage tank 2.

[0087] When using the injection means 3 configured as in this embodiment, it is possible to achieve substantially the same effects as when using the injection means 3 of the embodiment illustrated in Figures 1 to 5. Thus, the configuration of the injection means 3 that generates a swirling flow in which numerous bubbles of exhaust G rise in a spiral shape in the alkaline solution A is not limited to the configuration of the injection means 3 of the embodiment illustrated in Figures 1 to 5, and various other configurations are possible. For example, the injection means 3 can be configured such that a porous filter having numerous through-holes is provided at the bottom inside the storage tank 2, and the exhaust G sprayed from the spray nozzle 4a passes through the porous filter, thereby generating numerous bubbles of exhaust G in the alkaline solution A. The use of a porous filter allows for efficient formation of numerous bubbles of exhaust G.

[0088] The reduction system 1 of the present invention is not limited to the above-described exemplary embodiment and can have various other configurations. The manifold 21, dust collector 22, and heat removal tank 23 that constitute the exhaust supply line are not essential components and can be optionally provided as needed. For example, in a reduction system 1 that reduces carbon dioxide in the exhaust G of a single internal combustion engine 20, the manifold 21 does not need to be provided. For example, the exhaust port of the internal combustion engine 20 and the pumping device 24 can be directly connected by the vent pipe 5. Furthermore, for example, a system for purifying the exhaust G of the internal combustion engine 20 (e.g., a urea SCR system) can be interposed between the exhaust port of the internal combustion engine 20 and the injection means 3.

[0089] The solution generation tank 30, the agitator 31, and the raw water level adjustment tank 32 that constitute the solution supply line are not essential components and can be optionally provided as needed. The solution supply line may be configured in any manner as long as it can supply alkaline solution A to the storage tank 2, and various configurations other than those illustrated above are possible. For example, the solution supply line may be configured so that alkaline wastewater generated during construction work or pre-generated alkaline solution A is directly introduced into the storage tank 2 (2X). While the above example illustrates a case in which three storage tanks 2X-2Z are connected in series, the number of storage tanks 2 to be connected is not particularly limited. For example, two storage tanks 2 may be connected, or four or more storage tanks 2 may be connected. The reduction system 1 of the present invention may also be configured with a single storage tank 2.

[0090] DESCRIPTION OF SYMBOLS 1 Carbon dioxide emission reduction system 2, 2X to 2Z Storage tank 2a Inlet 2b Inlet 2c Exhaust port 2d Drain port 2e Projection 3 Injection means 4 Injection unit 4a Spray nozzle 4b Branch pipe section 5 Vent pipe 6 Connecting pipe 7 Exhaust pipe 8 Exhaust valve 9 Drain pipe 10 Drain valve 11 Discharge pipe 12 Discharge valve 13 Hydrogen ion concentration meter 14 Carbon dioxide concentration measuring device 15 Pressure gauge 16 Control device 17 Notch tank 20 Internal combustion engine 21 Manifold 22 Dust collector 23 Heat removal tank 24 Pressure transfer device 30 Solution generation tank 31 Agitator 32 Raw water level adjustment tank 40 Management device G Exhaust GP Treated exhaust A Alkaline solution AP Treated solution CW Cooling water R Recycled crushed stone RP Treated recycled crushed stone S Sediment W Water

Claims

1. A method for reducing carbon dioxide emissions, comprising: injecting exhaust gas discharged from an internal combustion engine into an alkaline solution stored in a storage tank, bringing the alkaline solution into contact with the exhaust gas inside the storage tank, and causing a neutralization reaction between the alkaline solution and the carbon dioxide contained in the exhaust gas, thereby reducing the amount of carbon dioxide contained in the exhaust gas, and discharging the exhaust gas with the reduced amount of carbon dioxide from an exhaust port of the storage tank.

2. A method for reducing carbon dioxide emissions as described in claim 1, comprising arranging a plurality of ejection nozzles to which the exhaust gas is supplied at a lower portion inside the storage tank, and ejecting the exhaust gas from each of the ejection nozzles, thereby generating a swirling flow in which a large number of exhaust gas bubbles rise in a spiral shape into the alkaline solution inside the storage tank.

3. A method for reducing carbon dioxide emissions as described in claim 1 or 2, wherein a protrusion provided on the inner surface of the storage tank slows down the rising speed of the exhaust gas bubbles rising through the alkaline solution.

4. A method for reducing carbon dioxide emissions as described in claims 1 to 3, in which the alkaline solution is produced using recycled crushed stone obtained by crushing waste concrete, and the produced alkaline solution is stored in the storage tank.

5. A plurality of the storage tanks are connected in series via an air vent pipe through which the exhaust gas flows and a connecting pipe through which the alkaline solution flows; The method for reducing carbon dioxide emissions according to claims 1 to 4, wherein the alkaline solution stored in the upstream storage tank, whose hydrogen ion concentration has been reduced by a neutralization reaction with the carbon dioxide contained in the exhaust air in the upstream storage tank, is discharged from a drain port of the upstream storage tank, and the alkaline solution discharged from the drain port flows into the downstream storage tank via the connecting pipe and is stored therein, and the exhaust air discharged from the exhaust port of the upstream storage tank is injected into the alkaline solution stored in the downstream storage tank via the vent pipe, so that the alkaline solution and the exhaust air come into contact with each other inside the downstream storage tank, thereby causing a neutralization reaction between the alkaline solution and the carbon dioxide contained in the exhaust air, thereby further reducing the carbon dioxide contained in the exhaust air and further reducing the hydrogen ion concentration of the alkaline solution, and the exhaust air with the further reduced carbon dioxide is discharged from the exhaust port of the downstream storage tank, and the alkaline solution with the further reduced hydrogen ion concentration is discharged from the drain port of the downstream storage tank.

6. A method for reducing carbon dioxide emissions as described in claim 5, in which the carbon dioxide concentration of the exhaust gas after passing through the alkaline solution in each of the storage tanks is measured, and the exhaust gas whose carbon dioxide concentration is below a predetermined standard value is not injected into the alkaline solution stored in the downstream storage tank, but is treated as treated exhaust gas.

7. A method for reducing carbon dioxide emissions as described in claim 5 or 6, in which the hydrogen ion concentration of the alkaline solution stored in each of the storage tanks is measured, and the alkaline solution whose hydrogen ion concentration is below a predetermined threshold value is not allowed to flow into the downstream storage tank, but is treated as a treated solution.

8. A method for reducing carbon dioxide emissions according to any one of claims 1 to 7, wherein the exhaust gas discharged from the internal combustion engine is subjected to heat removal in a heat removal tank, and the exhaust gas from which heat has been removed is injected into the alkaline solution stored in the storage tank.

9. A method for reducing carbon dioxide emissions according to any one of claims 1 to 8, comprising removing dust contained in the exhaust gas discharged from the internal combustion engine using a dust collector, and injecting the exhaust gas from which the dust has been removed into the alkaline solution stored in the storage tank.

10. A method for reducing carbon dioxide emissions as described in claims 1 to 9, comprising: connecting a raw water level adjustment tank for temporarily storing the generated alkaline solution to the storage tank with a connecting pipe; flowing the alkaline solution stored in the raw water level adjustment tank into the storage tank; and bringing the liquid level of the alkaline solution stored in the raw water level adjustment tank into a state in which the liquid level of the alkaline solution stored in the storage tank is made to match the liquid level of the alkaline solution stored in the storage tank.

11. A method for reducing carbon dioxide emissions as described in claim 10, in which the flow rate of the alkaline solution supplied to the raw water level adjustment tank is adjusted so as to maintain the liquid level of the alkaline solution stored in the raw water level adjustment tank at a predetermined height.

12. A carbon dioxide emission reduction system comprising: a storage tank in which an alkaline solution is stored; and an injection means for injecting exhaust gas discharged from an internal combustion engine into the alkaline solution stored in the storage tank, wherein the alkaline solution comes into contact with the exhaust gas injected by the injection means inside the storage tank, causing a neutralization reaction between the alkaline solution and the carbon dioxide contained in the exhaust gas, thereby reducing the carbon dioxide contained in the exhaust gas, and the exhaust gas with the reduced carbon dioxide content is discharged from an exhaust port of the storage tank.

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