JP3605515B2 - CO2 ocean discharge equipment - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a marine discharge apparatus for releasing carbon dioxide into the sea by dissolving it in seawater.
[0002]
[Prior art]
In recent years, global warming has become a major problem, and it has been pointed out that the concentration of carbon dioxide (CO ₂ ) in the atmosphere with a greenhouse effect, which has been pointed out as a possibility of causing climate change on a global scale, is increasing. It is particularly important to control the rise. As one of the measures, a concept has been proposed in which carbon dioxide in combustion exhaust gas discharged from thermal power plants and the like is collected and sent to the ocean, thereby isolating carbon dioxide from the atmosphere for a long time. In order to achieve this, it is necessary to ensure that no new environmental impacts are caused in the ocean that sends carbon dioxide.
[0003]
The following two types of systems have been proposed as systems for reducing the influence on the marine environment due to the feeding of carbon dioxide. One of them is a storage type, which is a method in which the area of influence is limited to a specific place and localized by storing carbon dioxide intensively in a place such as a hollow on the deep sea floor.
[0004]
Another system, called the dissolution-diffusion type, is a method in which carbon dioxide is dissolved in seawater, diluted dilutely and diffused widely to suppress the rise in the concentration of carbon dioxide in seawater. However, it is based on the idea that the concentration of carbon dioxide originally dissolved in seawater only increases to some extent.
[0005]
As a specific method in the dissolution-diffusion type, there is a middle-layer dilution discharge method in which a discharge point of carbon dioxide is moved by a ship to discharge carbon dioxide in a middle layer in the sea. This method will be described with reference to FIGS. FIG. 2 is an explanatory view schematically showing a system of a middle-layer dilution discharge method, and FIG. 3A is an explanatory view schematically showing a state in which carbon dioxide is discharged and diffused from a discharge pipe into the sea in the same method, and FIG. FIG. 3B is an enlarged view of a portion Z in FIG. 3A, and FIG. 4 is an explanatory view showing a state of droplets formed by discharging carbon dioxide from a discharge pipe.
[0006]
This middle-layer dilution discharge method liquefies the carbon dioxide separated and recovered from the flue gas in the land plant 1, fills the liquefied gas into the storage tank 2a, and transports the liquefied gas to the predetermined sea area by the liquefied gas carrier 2 where it is transported by sea. The liquid carbon dioxide inside the storage tank 2a is transferred to the storage tank 3a mounted on the work boat 3. The liquid carbon dioxide has, for example, a pressure of 6 atm and a temperature of -55 ° C. FIG. 5 is a diagram showing the phase state of carbon dioxide. As can be seen from this diagram, the above-mentioned 6 atm and a temperature of −55 ° C. are conditions under which liquid carbon dioxide can be obtained economically. The work boat 3 is provided with a discharge pipe 4 made of a very long steel pipe or the like suspended from the sea at a depth of 2000 m to 2500 m, and sends liquid carbon dioxide from the storage tank 3 a to the discharge pipe 4 and moves the carbon dioxide upward and downward at the lower end of the discharge pipe 4. The water is discharged into the sea from a plurality of discharge holes 5 formed side by side. The work boat 3 advances while discharging the liquid carbon dioxide into the sea from the hole 5 of the discharge pipe 4, thereby moving the discharge point of the carbon dioxide without being limited to a local area, thereby increasing the dilution of the carbon dioxide. Note that the carrier 2 and the work boat 3 may be different from each other, or may be shared by both. SL is the sea surface.
[0007]
The state of the carbon dioxide discharged from the discharge pipe 4 is assumed as follows from the current knowledge. The carbon dioxide 6 discharged into the sea from the hole 5 of the discharge pipe 4 does not immediately dissolve into the seawater, but a large number in the fluctuating flow field 9 due to the vortex 8 generated and left behind by the discharge pipe 4. Are dispersed and almost uniformly mixed with seawater. The discharge pipe 4 is inclined rearward in the traveling direction of the ship by the relative flow velocity with respect to the opposing ocean current, and proceeds while continuously generating a wake vortex 8 having a rotation axis substantially parallel to the pipe axis behind the discharge pipe 4. Go out. The pattern of the vortex 8 varies depending on conditions such as the shape, surface condition, dimensions and moving speed of the discharge pipe. It is considered that a swirl is generated from both sides and the fluctuating flow field 9 is left behind, in which carbon dioxide and seawater mix.
[0008]
Then, the carbon dioxide droplet 7 gradually rises in the seawater from the wake of the discharge pipe 4 while being dissolved in the surrounding seawater. That is, the diameter of the carbon dioxide droplet 7 is reduced by dissolving in the seawater while rising in the seawater. Then, in the process of ascending the droplet 7 to a certain height, all the carbon dioxide is dissolved in the seawater, and the droplet 7 disappears.
[0009]
The middle dilution discharge system discharges carbon dioxide in the sea (middle layer) at a depth of about 2000 m to 2500 m from the sea surface. In other words, when carbon dioxide is released in the sea above 2000m, droplets may reach the sea surface before all of the released carbon dioxide is dissolved in seawater, and in a sea with a depth of about 2000m to 2500m. The release of carbon dioxide allows all of the carbon dioxide to dissolve into the seawater before the droplets reach the sea surface.
[0010]
[Problems to be solved by the invention]
Thus, the middle dilution discharge method is considered to be a very promising method for releasing carbon dioxide into the ocean and sequestering it.
[0011]
However, this middle-diluted discharge system has the following problems.
[0012]
One of them is that the liquid carbon dioxide stored and transported in the storage tank is kept in a liquid state at a low temperature of -55 ° C. and 6 atm and a relatively low pressure due to the pressure resistance structure of the storage tank. However, liquid carbon dioxide is heated by the heat transferred from the seawater around the discharge pipe before it is sent into the discharge pipe, circulates inside the long discharge pipe, and is discharged into the sea. . Then, when the liquid carbon dioxide flows inside the discharge pipe, the pressure of the liquid carbon dioxide increases substantially linearly from the pressure at sea due to its own weight, but the pressure of the liquid carbon dioxide does not rise completely If the temperature of the liquid carbon dioxide rises rapidly in the upper part, the liquid carbon dioxide evaporates into gaseous carbon dioxide as is clear from the diagram of FIG. 5, which hinders the discharge of the liquid carbon dioxide into the sea. Become.
[0013]
The workboat is equipped with a very long discharge pipe suspended from the sea at a depth of 2000 m to 2500 m. I do. Here, if the discharge pipe is a rigid body formed entirely of a metal pipe such as a steel pipe, and if the mounting portion of the discharge pipe in the work boat is configured with a rigid structure, the discharge pipe is inclined by the sailing of the work boat In such a case, a large bending load is applied to the mounting portion of the discharge pipe in the work boat, and the load on the mounting portion of the discharge pipe is large, and a problem occurs in durability.
[0014]
As a countermeasure, the discharge pipe is rotatably mounted as a discharge pipe mounting part on the work boat, so that the discharge pipe can rotate and tilt when the work boat sails, and the bending load on the discharge pipe mounting part And a structure for reducing this. However, if a very long discharge pipe is hung and rotatably mounted, the structure of the mounting portion is large and robust, which causes a practical problem.
[0015]
Accordingly, there is a demand for a discharge device that can suppress a rise in the temperature of liquid carbon dioxide flowing inside and reduce the load on a mounting portion of a ship.
[0016]
The present invention has been made in view of the above circumstances, and provides a marine discharge apparatus for carbon dioxide having a discharge pipe capable of suppressing a rise in the temperature of liquid carbon dioxide flowing inside and reducing the load on a mounting portion of a ship. That is the task.
[0017]
[Means for Solving the Problems]
The marine discharge device for carbon dioxide according to the first aspect of the present invention is an apparatus for sending liquid carbon dioxide into a discharge pipe suspended in the sea from a ship sailing on the sea and discharging the liquid carbon dioxide into the sea from a hole formed in the discharge pipe. Wherein the upper part of the discharge pipe is formed of a flexible hose covered with a synthetic resin, and the lower part following the flexible hose is formed of a metal pipe.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to FIG.
[0020]
The present invention is directed to an apparatus for discharging the liquid carbon dioxide shown in FIGS. 2 to 4 to the ocean by a middle-diluted discharge method described above. In FIG. 1, the same parts as those in FIG. I have. That is, in the drawing, reference numeral 3 denotes a work boat, and 3a denotes a tank mounted on the work boat 3 for storing liquid carbon dioxide.
[0021]
The features of the present invention will be described.
[0022]
In the figure, reference numeral 11 denotes a discharge pipe, which is attached to the work boat 3 and discharges liquid carbon dioxide into the sea. The discharge pipe 11 has a length which can be suspended in the sea at a depth of 2000 to 3000 m and towed in an inclined state. have. The upper part of the discharge pipe 11 is constituted by a flexible hose 12, and the lower part following the flexible hose 12 is constituted by a metal tube 13.
[0023]
The flexible hose 12 is formed by spirally winding a steel thin plate into a plurality of layers and further covering with a synthetic resin to secure tensile strength and pressure resistance. The thermal conductivity of plastic is much higher than that of metal material. The small size also has a high heat insulating effect.
[0024]
Such a flexible hose 12 forms an upper part of the discharge pipe 11. The upper part of the discharge pipe 11 corresponds to the surface layer in the sea at a depth of several hundred meters from the sea surface. The temperature of the seawater is higher than that of the middle and deep layers, and the heat of the seawater passes through the discharge pipe 11. The degree to which the temperature of the liquid carbon dioxide is increased by transmitting to the liquid carbon dioxide flowing inside the discharge pipe 11 is high. The upper part of the discharge pipe 11 constituted by the flexible hose 12 covered with a synthetic resin (plastic) having a high heat insulating effect receives liquid carbon dioxide flowing inside the discharge pipe 11 receiving heat of seawater having a high water temperature in the surface layer in the sea. Temperature rise. Further, the upper part of the discharge pipe 11 constituted by the flexible hose 12 covered with a synthetic resin (plastic) is responsible for bending of the discharge pipe 11 when the discharge pipe 11 is inclined as described later, and the discharge pipe in the work boat 3. This prevents a bending load from acting on the mounting portion 11 (the mounting portion of the flexible hose 12). The flexible hose 12 has an upper end attached and fixed to an attachment portion 15 provided on the work boat 3 with an appropriate rigid structure, and is suspended from the work boat 3 to a surface layer in the sea.
[0025]
The metal pipe 13 is formed of a steel pipe or the like, and has a length obtained by subtracting the length of the flexible hose 12 from the entire length of the discharge pipe 11. A plurality of discharge holes 14 are formed at the lower end of the metal tube 13 at intervals in the axial direction. The lower part of the discharge pipe 11 is composed of the metal pipe 13 because the metal pipe 13 is inexpensive as compared with the flexible hose 12 and compared with the case where the entire length is formed by the flexible hose 12 in manufacturing the discharge pipe 11. Because it can be manufactured economically. The upper end of the metal tube 13 is attached to the lower end of the flexible hose 12 in a liquid-tight manner by an appropriate rigid configuration.
[0026]
The discharge device configured as described above sends the liquid carbon dioxide stored in the storage tank 3a mounted on the work boat 3 from the work boat 3 to the inside of the discharge pipe 11 suspended from the sea, and discharges it into the sea. That is, the liquid carbon dioxide flows first down the inside of the flexible hose 12 constituting the upper part of the discharge pipe 11, then flows down the inside of the metal pipe 13 and discharges into the sea from a plurality of discharge holes 14 formed at the lower end of the metal pipe 13. Is done. In this case, on the surface layer in the sea where the temperature of the seawater is high, the heat of the seawater having a high water temperature is transmitted to the carbon dioxide flowing inside the flexible hose 12 via the flexible hose 12 because the flexible hose 12 having a high heat insulating effect is located on the surface layer in the sea. That is suppressed. For this reason, the temperature rise of the carbon dioxide flowing inside the flexible hose 12 due to the surface water in the sea can be suppressed. Therefore, when the liquid carbon dioxide flows through the inside of the discharge pipe 11, it can be suppressed that the temperature rises due to the heat of the seawater and evaporates.
[0027]
Then, the work boat 3 sails to move the discharge point. For this reason, the discharge pipe 11 is inclined rearward in the ship traveling direction by the relative flow velocity with respect to the opposing ocean current in the sea. In this case, since the metal pipe 13 constituting the discharge pipe 11 has rigidity, it does not bend and linearly inclines rearward in the ship traveling direction. The flexible hose 12 connected to the metal pipe 13 and constituting the upper part of the discharge pipe 11 is subjected to a force tilting rearward with the tilt displacement of the metal pipe 13. Here, since the upper end of the flexible hose 12 is fixed to the work boat 3 with a rigid structure , the flexible hose 12 bends so as to tilt rearward when a force tilting rearward in the direction of travel of the boat is applied. That is, the flexible hose 12 absorbs a force applied to the discharge pipe 11 so as to incline rearward in the ship traveling direction, and allows bending by the force. Therefore, when the discharge pipe 11 is inclined and displaced rearward in the direction of travel of the ship, the mounting portion 15 of the discharge pipe 11 (flexible hose 12) in the work boat 3 is moved rearward in the direction of travel of the vessel. It is possible to suppress the direct application of the bending load inclined toward the mounting direction, reduce the load on the mounting portion 15 from the bending load, and improve the durability. Further, since the mounting portion 15 of the discharge pipe 11 in the work boat 3 has a rigid structure, the structure of the mounting portion is simplified and downsized as compared with a structure in which the discharge pipe 11 is rotatably mounted. The manufacturing cost of the part 15 can be reduced.
[0028]
The present invention is not limited to the above-described embodiment, and can be implemented with various modifications. For example, the configuration of the flexible hose 12 is not limited to the embodiment described above. In the above-described embodiment, only the upper part of the discharge pipe 11 is formed of a flexible hose, but the present invention is not limited to this, and the entire length of the discharge pipe 11 may be formed of a flexible hose. Also in this case, due to the characteristics of the flexible hose, the temperature of the liquid carbon dioxide flowing through the discharge pipe is prevented from rising due to seawater, and the bending load is not directly applied to the mounting portion of the discharge pipe.
[0029]
【The invention's effect】
According to the marine discharge device for carbon dioxide of the present invention, at least a part of the discharge pipe for discharging liquid carbon dioxide attached to a ship and suspended in the sea is formed of a flexible hose. The effect prevents the temperature of the liquid carbon dioxide flowing through the discharge pipe from rising due to seawater, thereby suppressing the vaporization of the liquid carbon dioxide, and installing the discharge pipe in the ship when the discharge pipe is inclined due to the navigation of the ship The application of a bending load to the portion can be suppressed.
[0030]
In particular, by configuring the upper part of the discharge pipe with a flexible hose, it is possible to suppress the temperature rise of the liquid carbon dioxide flowing inside the discharge pipe due to seawater on the surface layer in the sea where the water temperature is high, and the bending load is applied to the mounting part of the discharge pipe. Addition can be more effectively suppressed.
[Brief description of the drawings]
FIG. 1 is a view schematically showing a marine discharge device for carbon dioxide according to an embodiment of the present invention.
FIG. 2 is a diagram schematically showing a system for discharging carbon dioxide to the ocean.
FIG. 3 is a diagram schematically showing a marine discharge device for carbon dioxide.
FIG. 4 is a diagram schematically showing a state of liquid carbon dioxide discharged into the sea by the discharge device.
FIG. 5 is a diagram showing a phase state of carbon dioxide.
[Explanation of symbols]
3. Work boat,
11 ... discharge pipe,
12 ... Flexible hose,
13 ... metal tube,
14 ... discharge holes,
15 ... Mounting part.

Claims (1)

A device that sends liquid carbon dioxide into a discharge pipe suspended under the sea from a ship sailing on the sea and discharges it into the sea through a hole formed in the discharge pipe. It consists of a hose, marine discharge device of carbon dioxide, characterized in that the lower that followed the flexible hose is made of a metal tube.

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