JP3552919B2 - A device that dilutes and releases carbon dioxide to the ocean - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an apparatus for diluting and releasing carbon dioxide dissolved in seawater by discharging collected carbon dioxide into the sea.
[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 avoid causing new environmental impacts 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 liquid carbon dioxide is moved by a ship to discharge liquid carbon dioxide in a middle layer in the sea. This method will be described with reference to FIGS. 4 is an explanatory view schematically showing a system of a middle-layer dilution discharge system, FIG. 5 (a) is an explanatory view schematically showing a discharge device in the same system, and FIG. 5 (b) is an X part in FIG. 5 (a). FIG. 6 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. 7 is a diagram showing the phase state of carbon dioxide. As can be seen from the diagram, the condition of 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. The discharge pipe 4 has a lower end face closed and a plurality of discharge holes 5 formed in a peripheral wall at the lower end. They are arranged in the same row at intervals in the vertical direction. Then, the liquid carbon dioxide is sent from the storage tank 3a to the discharge pipe 4 and discharged into the sea from a plurality of discharge holes 5 formed at the lower end of the discharge pipe 4 and arranged vertically. The work boat 3 advances while discharging the liquid carbon dioxide from the hole 5 of the discharge pipe 4 into the sea, thereby moving the discharge point of the liquid carbon dioxide without being limited to a local area, thereby increasing the dilution of the liquid 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 liquid carbon dioxide discharged from the discharge pipe 4 is assumed as follows from the current knowledge. The liquid carbon dioxide 6 discharged into the sea from the hole 5 of the discharge pipe 4 does not immediately dissolve in the seawater, but in the fluctuating flow field 9 due to the vortex 8 generated and left behind by the discharge pipe 4. A large number of droplets 7 are dispersed and almost uniformly mixed with seawater. The discharge pipe 4 receives the resistance of the seawater due to the running of the work boat 3, and is inclined rearward in the direction of the ship due to the relative flow velocity with the ocean current, and has a rotation axis behind and substantially parallel to the axis. It progresses while continuously generating wake vortices. The pattern of the vortex 8 varies depending on conditions such as the shape, surface condition, dimensions and moving speed of the discharge pipe. However, when a pipe having an outer diameter of several 10 cm advances at a speed of several knots, the pipe normally moves left and right in the direction of travel. It is considered that the swirl is generated from both sides and the fluctuating flow field 9 is left behind, in which the liquid carbon dioxide and the seawater mix.
[0008]
Then, the liquid carbon dioxide droplet 7 gradually rises in the seawater from the wake of the discharge pipe 4 while being further dissolved in the surrounding seawater. That is, the diameter of the droplet 7 of the liquid carbon dioxide is reduced by being dissolved in the seawater while rising in the seawater. Then, during the process in which the droplet 7 rises to a certain height, all the liquid carbon dioxide is dissolved in the seawater, and the droplet 7 disappears.
[0009]
The middle-layer dilution discharge method discharges liquid carbon dioxide in the sea at a depth of about 2000 m to 2500 m (middle layer) from the sea surface. That is, when liquid carbon dioxide is discharged in the sea above 2000m, the liquid droplets may reach the sea surface before all the discharged liquid carbon dioxide does not dissolve in the seawater, and a depth of about 2000m to 2500m When the liquid carbon dioxide is discharged in the sea, all the liquid carbon dioxide can be dissolved in the seawater before the droplet reaches the sea surface.
[0010]
[Problems to be solved by the invention]
The discharge device employing the middle-level dilution discharge method is considered to be a very promising device for discharging and isolating liquid carbon dioxide into the ocean, but this discharge device has the following problems.
[0011]
In the middle-dilution discharge method, in order to allow all liquid carbon dioxide to be dissolved in seawater before the liquid carbon dioxide droplets discharged in the sea at a depth of about 2000 m to 2500 m (middle layer) from the sea surface reach the sea surface. It is necessary to adjust the diameter of the droplet generated when the liquid carbon dioxide is discharged to a required size in consideration of the rising distance of the droplet. For this reason, the diameter of the discharge hole 5 is set so as to generate a droplet of a required size.
[0012]
By the way, in the discharge pipe currently proposed, the outer surface of the peripheral wall on which the discharge pipe 3 is formed has a uniform arc surface. However, when distilling the liquid carbon dioxide with the discharge pipe inclined, according to the experimental results, as shown in FIG. 8, the discharge pipe 4 is inclined and the rear half of the ship traveling direction (upper half) as shown in FIG. The liquid carbon dioxide 6 discharged from the discharge hole 5 formed in the peripheral wall portion 4b of the above becomes sufficient droplets 7 to be dispersed into the sea and rise. However, when the discharge pipe 4 is inclined, the liquid carbon dioxide 6 discharged from the discharge hole 5 formed in the peripheral wall portion 4a, which is the front half (the lower half) on the ship's running direction, has sufficiently developed droplets. Before flowing into the discharge hole 5, the liquid begins to flow from the opening directly along the outer surface of the discharge pipe 4, and droplets 7 form from the outer surface of the peripheral wall portion of the rear half (upper half) of the discharge pipe 4 in the ship traveling direction. Rise. This is considered to be due to the influence of the buoyancy of the droplet and the property of the droplet trying to flow along the object.
[0013]
Then, in a state where the discharge pipe 4 is inclined, the liquid carbon dioxide discharged from the large number of discharge holes 5 formed in the peripheral wall portion 4a which is the front half (the lower half) on the ship traveling direction merges to form large droplets. 7A, and it is assumed that a droplet of the required size that is expected cannot be obtained.
[0014]
The present invention has been made based on the above circumstances, and it is possible to adjust the size of the liquid carbon dioxide droplets discharged regardless of the position of the discharge holes in the inclined discharge pipe, and to perform a favorable discharge. It is an object to provide a device for diluting and discharging carbon into the ocean.
[0015]
[Means for Solving the Problems]
The apparatus for diluting and discharging carbon dioxide to the ocean according to the invention of claim 1 is configured such that, while navigating a ship having a discharge pipe suspended in the sea and towing the discharge pipe in an inclined manner, liquid carbon dioxide is discharged to the discharge pipe. In a discharge device that sends in and discharges from the discharge pipe into the sea,
A plurality of discharge holes for discharging the liquid carbon dioxide fed into the sea are formed on the peripheral wall of the discharge pipe, and at least the outer surface of a peripheral wall portion that is a half of the front side in the ship traveling direction in a state where the discharge pipe is inclined. In addition, a protruding edge protruding outward is formed so as to surround the opening of each discharge hole formed in the peripheral wall portion.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to FIGS.
[0017]
FIG. 1 is a diagram schematically showing a discharge device according to this embodiment, and FIG. 2A is an enlarged schematic diagram showing a liquid carbon dioxide discharge portion of a discharge pipe in the discharge device. FIG. 2B is a sectional view taken along the line Z-Z in FIG. The present invention is directed to an apparatus for discharging the liquid carbon dioxide shown in FIGS. 4 to 6 to the ocean by a middle-dilution discharge method, and the same parts in FIG. 1 as those in FIG. Is shown. In the figure, reference numeral 3 denotes a work boat, 3a denotes a tank for storing liquid carbon dioxide mounted on the work boat 3, and 4 denotes a liquid carbon dioxide attached to the work boat 3 and suspended under the sea and stored in the tank 3a. It is a discharge pipe that sends in, discharges, and discharges into the sea.
[0018]
In the present invention, the following configuration is employed to discharge liquid carbon dioxide to the lower end of the discharge pipe 4. The discharge pipe 4 has a circular cross section, and has a length that allows it to be suspended from the work boat 3 in the sea at a depth of 2000 m to 2500 m and towed by the work boat 3. A large number of discharge holes 5 are formed in the peripheral wall at the lower end portion of the discharge pipe 4 over the entire circumferential direction within a predetermined length in the axial direction. In addition, the size required at the time of discharge in order to allow all the carbon dioxide to be dissolved in the seawater before the droplets of the released carbon dioxide rise in the sea at a depth of about 2000 m to 2500 m (middle layer) from the sea surface and reach the sea surface. The size of the diameter of the discharge hole 5 is set so as to obtain the liquid droplets. For example, in order to discharge the droplet with a diameter of 5 to 15 mm, the diameter of the discharge hole 5 is set to 3 to 10 mm (the diameter of the discharge pipe 4 is several tens of cm).
[0019]
In the present invention, on the outer surface of the peripheral wall portion that becomes the front half (lower half) 4a in the ship traveling direction in a state where the discharge pipe 4 is towed by the work boat 3 and is inclined in the discharge pipe 4, Protruding edges 11 are provided to protrude outward around the openings of the discharge holes 5 formed in the portions. When the discharge pipe 4 is towed by the work boat 3 and the liquid carbon dioxide is discharged from the discharge hole 5 in a state where the discharge pipe 4 is inclined, the droplet 7 of the liquid carbon dioxide is formed along the outer surface of the discharge pipe 4. The height of the protruding edge 11 from the outer surface is set so that the liquid carbon dioxide droplet 7 discharged from the opening of the discharge hole 5 separates from the outer surface of the discharge pipe 4 to prevent seawater from moving. Moving inside is height. The height of each protruding edge 11 is made uniform. The discharge pipe 4 is made of a steel pipe or the like, and the protruding edge 11 is formed integrally, for example, when the discharge pipe 4 is manufactured, or a ring-shaped member is fixed to the discharge pipe 4.
[0020]
In the discharge device configured as described above, when the work boat 3 is sailed and the discharge pipe 4 is towed, the discharge pipe 4 is inclined toward the rear side of the ship traveling direction A due to seawater resistance (ship navigation). Running direction). When the liquid carbon dioxide stored in the tank 3a mounted on the work boat 3 was sent from the upper end of the discharge pipe 4 to the inside, the liquid carbon dioxide flowed inside the discharge pipe 4, reached the lower end, and was formed at the lower end. The water is discharged from the discharge hole 5 into seawater.
[0021]
Here, the liquid carbon dioxide 6 discharged from each of the discharge holes 5 located on the peripheral wall portion which is the rear half (upper half) 4b of the discharge pipe 4 which is towed by the work boat 3 and is inclined in the ship traveling direction, Since the upper surface side is seawater, the liquid drops 7 are satisfactorily formed as droplets 7 and disperse into seawater and rise. On the other hand, the liquid carbon dioxide 6 discharged from the discharge holes 5 located on the peripheral wall portion of the discharge pipe 4 which is towed by the work boat 3 and becomes the front half (top half) 4a of the inclined discharge pipe 4 in the ship traveling direction, After passing through the opening of the discharge hole 5 and further passing through the protruding edge 11 provided surrounding the opening of the discharge hole 5 and protruding from the outer surface of the peripheral wall portion at a required height, and then entering seawater and moving. Spread. That is, the liquid carbon dioxide is discharged into the seawater from the tip of the protruding edge 11 protruding from the outer surface of the peripheral wall portion at a required height. That is, the liquid carbon dioxide does not move upward along the outer surface of the peripheral wall portion directly from the opening of the discharge hole 5 at the stage where the droplet is not sufficiently developed, but separates from the outer surface of the peripheral wall portion by the height of the protruding edge 11. Is released into the seawater from the location where it was placed.
[0022]
Therefore, the liquid carbon dioxide discharged from each discharge hole 5 located on the peripheral wall portion which is the front half (upper half) 4a of the discharge pipe 4 towed by the work boat 3 and becomes inclined in the ship traveling direction A is respectively Each of the discharge holes 5 becomes a droplet 7 independently and sufficiently dispersed in the sea and rises. In this manner, the liquid carbon dioxide can be satisfactorily discharged from each discharge hole 5 of the discharge pipe 4 as droplets of a size required for dilution in the sea of a predetermined middle layer in advance. As a result, the droplet 7 can be well diluted in the middle sea.
[0023]
Note that the shape of the protruding edge provided on the outer surface of the discharge pipe 4 so as to surround the opening of the discharge hole 5 is not limited to the above-described embodiment, and can be variously modified and implemented. 3A and 3B show another form of the protruding edge. FIG. 3A is an enlarged view of a discharge hole forming portion in a discharge pipe, and FIG. 3B is a line YY in FIG. FIG. In FIG. 3, the lower part of the discharge hole forming portion of the discharge pipe 4 is provided with the protruding edge 11 having the height shown in FIG. 2, and the upper portion of the discharge hole forming portion has a protruding edge 11A whose height is higher than the protruding edge 11. Is provided.
[0024]
As described above, the height of the protruding edge can be changed as required in the discharge hole forming portion, and as shown in FIG. 3, it can be made partially different in the discharge hole forming portion. . It is also possible to combine a plurality of protruding edges having different heights in the same discharge hole forming portion at different positions like a staggered arrangement.
[0025]
Furthermore, in the above-described embodiment, at least the outer surface of the peripheral wall portion 4a, which is a half of the front side in the ship running direction in a state where the discharge pipe 4 is inclined, surrounds the openings of the respective discharge holes formed in the peripheral wall portion. The projecting edge 11 protruding outward is formed, but is not limited thereto, and the projecting edge is formed in each discharge hole formed in the entire circumferential direction of the peripheral wall portion 4b including the rear half of the ship traveling direction. Is also possible. In this case, it is possible to cope with any part of the peripheral wall portion of the discharge hole forming portion of the discharge pipe 4 which becomes half of the rear side in the ship running direction when the discharge pipe 4 is towed and inclined at the time of being inclined.
[0026]
【The invention's effect】
As described above, according to the apparatus of the present invention for diluting and discharging carbon dioxide to the ocean, when discharging a liquid carbon dioxide from the discharge pipe into the sea while navigating a ship and tilting the discharge pipe tow, Liquid carbon dioxide discharged from each discharge hole located on the peripheral wall portion that is the front half (upper surface side half) of the discharge pipe in the ship running direction protrudes from the outer surface of the peripheral wall portion around the discharge hole opening. After passing through the protruding edge, the water is discharged into the seawater from a position that is at the height of the protruding edge from the outer surface of the surrounding wall, so that the towed towed ship and the inclined discharge pipe are on the front half (in the top half) The liquid carbon dioxide discharged from the discharge hole located in the peripheral wall portion is prevented from directly moving along the outer surface of the peripheral wall portion from the opening of the discharge hole at a stage where the droplet does not sufficiently develop, and each discharge is performed. In the sea, enough droplets are formed independently for each hole The liquid carbon dioxide droplets discharged from each discharge hole of the discharge pipe can be made to disperse and move, so that the liquid carbon dioxide droplets can be adjusted to a diameter of a predetermined required size and can be well diluted in seawater. be able to.
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing an apparatus for diluting and discharging carbon dioxide to the ocean according to an embodiment of the present invention.
FIG. 2 is an enlarged view showing a discharge hole forming portion of a discharge pipe provided in the discharge device according to the embodiment.
FIG. 3 is an enlarged view showing another embodiment of a discharge hole forming portion of a discharge pipe provided in a discharge device.
FIG. 4 is a diagram showing a system for discharging carbon dioxide to the ocean.
FIG. 5 is a diagram schematically showing an apparatus for diluting and discharging carbon dioxide into the ocean.
FIG. 6 is a diagram schematically showing a state of liquid carbon dioxide discharged into the sea by the discharge device.
FIG. 7 is a diagram showing a phase state of carbon dioxide.
FIG. 8 is a view schematically showing a discharge pipe provided in a conventional discharge device.
[Explanation of symbols]
3. Work boat,
4 ... discharge pipe,
5 ... discharge hole,
6 ... liquid carbon dioxide,
7 ... droplets,
11 ... projecting edge.

Claims (1)

In a discharge device for navigating a ship with a discharge pipe suspended in the sea and towing the discharge pipe in an inclined manner, sending liquid carbon dioxide to the discharge pipe and discharging the liquid carbon dioxide from the discharge pipe into the sea,
A plurality of discharge holes for discharging the liquid carbon dioxide fed into the sea are formed on the peripheral wall of the discharge pipe, and at least the outer surface of a peripheral wall portion that is a half of the front side in the ship traveling direction in a state where the discharge pipe is inclined. A diluting and discharging apparatus for discharging carbon dioxide to the ocean, wherein a protruding edge protruding outward is formed so as to surround an opening of each discharge hole formed in the peripheral wall portion.

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