JP3583624B2 - Apparatus for diluting carbon dioxide into the ocean - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a device for diluting and releasing carbon dioxide into the sea by discharging recovered carbon dioxide into the sea and 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 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. FIG. 4 is an explanatory view schematically showing a system of a middle-layer dilution and discharge system, FIG. 5A is an explanatory view schematically showing a dilution and discharge apparatus in the same system, and FIG. 5B is a Z of FIG. 5A. FIG. 6 is an explanatory diagram showing a state of a droplet 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 pressure of 6 atm and the 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 into the seawater, and the discharge pipe 4 generates a large number in a fluctuating flow field 9 due to the vortex 8 generated and left behind in the wake. The 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]
As described above, it is considered that the diluting and discharging apparatus employing the middle-layer diluting and discharging method is a very promising apparatus for discharging and isolating liquid carbon dioxide into the ocean, but this diluting and discharging apparatus has the following problems. is there.
[0011]
At the time when the supply of the liquid carbon dioxide to the discharge pipe 4 is started, the seawater enters the discharge pipe 4 suspended in the sea through the discharge hole 5. In this state, when seawater and liquid carbon dioxide come into contact with each other inside the discharge pipe 4, or when seawater comes into contact with gaseous carbon dioxide, as shown in FIG. 7, depending on temperature and pressure conditions, seawater and liquid carbon dioxide come into contact with each other. A solid hydrate (clathrate) is generated at the contact portion where water and gaseous carbon dioxide come into contact with each other, and the inside of the discharge pipe 4 may be blocked by this hydrate. As a result, the inside of the discharge pipe 4 is closed and the descent of the liquid carbon dioxide is prevented, and it becomes difficult to discharge the liquid carbon dioxide into the sea.
[0012]
The present invention has been made in view of the above circumstances, the contact portion between seawater and liquid carbon dioxide in the discharge pipe, the state of the contact portion between seawater and gaseous carbon dioxide to control the discharge of liquid carbon dioxide satisfactorily It is an object of the present invention to provide an apparatus for diluting and releasing carbon dioxide into the ocean.
[0013]
[Means for Solving the Problems]
The apparatus for diluting and releasing carbon dioxide into the ocean of the invention according to 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 dilution discharge device that discharges and discharges into the sea from a discharge hole formed in the discharge pipe,
An electric heater is provided at a position corresponding to a contact portion where seawater and carbon dioxide come into contact with each other in a state where seawater is present inside the discharge pipe, as an electric heater for heating the contact portion.
[0014]
Here, the contact portion where seawater and carbon dioxide are in contact means a contact portion where seawater and liquid carbon dioxide are in contact and a contact portion where seawater and gaseous carbon dioxide are in contact.
[0017]
According to a second aspect of the present invention, in the apparatus for diluting carbon dioxide into the ocean according to the first aspect, the heater is vertically movable.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to the drawings.
[0019]
The inventor of the present invention, when sending liquid carbon dioxide into the discharge pipe, if the seawater and liquid carbon dioxide contained inside the discharge pipe come into contact with each other, the seawater freezes at the contact portion and hinders the delivery. In order to avoid this situation, gaseous carbon dioxide at normal temperature is first sent into the discharge pipe and lowered to a position corresponding to the pressure, and gaseous carbon dioxide that comes in contact with seawater at that position is changed according to the ambient temperature. It proposes a method of solidifying and liquefying, and then sending liquid carbon dioxide to the discharge pipe as a steady feed and discharging it into the sea. In this method, when seawater comes into contact with gaseous carbon dioxide, and when gaseous carbon dioxide solidifies at ambient temperature and comes into contact with liquid carbon dioxide and seawater, hydrates may be generated at the contact portion. In the embodiments described below, the formation of a hydrate is suppressed in this state.
[0020]
The inventor of the present invention has also proposed a method of sending gaseous carbon dioxide to the discharge pipe when stopping the supply of liquid carbon dioxide.However, in this case, the same state as described above occurs. Can be directed to the invention,
A first embodiment will be described with reference to FIG.
[0021]
FIG. 1 is a view schematically showing a dilution and discharge apparatus according to this embodiment. This dilution and discharge apparatus is an apparatus for discharging the liquid carbon dioxide shown in FIGS. In FIG. 1, the same parts as those in FIG. 5 are denoted by the same reference numerals. That is, in the drawing, 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 tank attached to the work boat 3 and suspends the liquid carbon dioxide suspended in the sea and stored in the tank 3a. This is a discharge pipe that is sent in from the upper end and then released into the sea. The discharge pipe 4 has a length capable of being inclined and towed in a middle layer sea of 2000 m to 2500 m, and has many discharge holes (not shown) for discharging liquid carbon dioxide fed to the lower end into the sea. 5 are formed.
[0022]
An annular heater 21 that surrounds the discharge pipe 4 from outside is provided at a position corresponding to a contact portion of the discharge pipe 4 where the seawater 10 and the liquid carbon dioxide 6 that are inside the discharge pipe 4 come into contact with each other. Installation fixed. The heater 21 is installed at a position described below. When the liquid carbon dioxide 6 is sent into the discharge pipe 4, gaseous carbon dioxide 6A is first sent into the discharge pipe 4, and the gaseous carbon dioxide 6A contacts the seawater 10 contained in the discharge pipe 4 to form The seawater 10 is pushed down to a depth position corresponding to the pressure of the carbon 6A and stopped. Here, when the gaseous carbon dioxide 6A that comes into contact with the seawater 10 solidifies and liquefies due to the ambient temperature, the heater 21 is installed at a location corresponding to the contact portion where the liquid carbon dioxide 6 comes into contact with the seawater 10. . The position of the contact portion is determined according to the pressure of gaseous carbon dioxide. For example, when gaseous carbon dioxide is fed at 6 atm and 20 ° C., the contact portion becomes a position at a depth of 600 m.
[0023]
When the liquid carbon dioxide 6 and the seawater 10 come into contact with each other at this contact portion, a solid hydrate is formed, and the inside of the discharge pipe 4 is closed by the hydrate. As shown by the line A in the diagram of FIG. 7, the temperature at which the liquid carbon dioxide 6 and the seawater 10 come into contact with each other to form a hydrate is 10 ° C. in the case of 45 atm or more, and 10 ° C. in the case of less than 45 atm. Gradually decreases from 10 ° C. as the atmospheric pressure decreases. Therefore, the heater 21 heats the liquid carbon dioxide 6 and the seawater 10 at the contact portion so as to exceed the temperature of 10 ° C. to suppress the generation of hydrate. The liquid carbon dioxide is kept at 45 atm or more.
[0024]
The heater 21 of this embodiment has an electric heater 22 mounted thereon as a heat source, and is connected to a power supply 24 mounted on the work boat 3 via a cable 23. A thermometer (not shown) for measuring the temperature of the discharge pipe 4 is provided at a position corresponding to a contact portion where the seawater 10 and the liquid carbon dioxide 6 contained in the discharge pipe 4 come into contact with each other. The temperature information from the thermometer is used to control the operation of heating the heater 21. The electric heater 22 may be mounted on the heater 21.
[0025]
The dilution and discharge device configured as described above sails the work boat 3 at sea, tow the discharge pipe 4 while tilting the discharge pipe 4, and passes the liquid carbon dioxide stored in the tank 3a mounted on the work boat 3 through the discharge pipe 4. Release into the sea. Before the discharge, seawater is contained in the discharge pipe 4. First, when gaseous carbon dioxide 6A at a predetermined pressure and temperature, for example, 6 atm and 20 ° C., is sent at the beginning of discharge, gaseous carbon dioxide 6A descends while contacting seawater 10 contained in discharge pipe 4 and gaseous carbon dioxide The seawater 10 is pushed down to a depth position corresponding to the pressure of the carbon 6A, for example, 600 m and stopped. The gaseous carbon dioxide 6A that comes into contact with the seawater 10 solidifies and liquefies at ambient temperature to become liquid carbon dioxide 6.
[0026]
On the other hand, at the time of starting discharge, the cable 23 is connected to the electric heater 22 of the heater 21 installed in the discharge pipe 4 corresponding to the position of the contact portion between the liquid carbon dioxide 6 and the seawater 10 from the power supply 24 provided in the work boat 3. Supply power through. The electric heater 22 receiving the electric power generates heat and heats the contact portion between the liquid carbon dioxide 6 and the seawater 10 inside the discharge pipe 4 via the peripheral wall of the discharge pipe 4. This heating temperature is a temperature at which hydrate formation is suppressed, that is, a temperature exceeding 10 ° C. as described above. This suppresses the formation of hydrate due to the contact between the liquid carbon dioxide 6 and the seawater 10 in the discharge pipe 4 at the contact portion between the liquid carbon dioxide 6 and the seawater 10. Can be prevented.
[0027]
Further, the same configuration is applied to the contact between the seawater 10 and the gaseous carbon dioxide. When the seawater 10 and the gaseous carbon dioxide come into contact with each other in the discharge pipe 4, the heater heats this contact portion to generate water. Reduce the occurrence of Japanese food.
[0028]
FIG. 2 is a diagram schematically illustrating a dilution and discharge device according to a second embodiment in which the form of the heater is different. 2, the same parts as those in FIG. 1 are denoted by the same reference numerals. In this embodiment, a heater 25 using seawater as a heat source is used as a heater for heating a contact portion between the seawater 10 and the liquid carbon dioxide 6 in the discharge pipe 4, and the heater 25 is provided outside the discharge pipe 4. And a pump 27 for feeding seawater from the seawater inlet to the heater body 25, and a seawater near the sea surface SL of the ocean connected to the suction port of the pump 27. A water suction pipe 28 for taking in (the part having the highest temperature as seawater) is provided. The water absorption pipe 28 is held along the discharge pipe 4. Although not shown, the pump 27 is connected to a controller provided on the work boat via a cable so that the driving thereof is controlled.
[0029]
Then, the pump 27 is driven to take in the seawater near the sea surface SL of the ocean from the water suction pipe 28 and suck the seawater into the heater main body 26. The seawater inside the heater main body 26 heats a contact portion between the seawater 10 and the liquid carbon dioxide 6 in the discharge pipe 4, and raises the contact portion to a temperature at which hydrate formation is suppressed. The seawater of the heater main body 26 whose temperature has been lowered by this heating is discharged into the sea. Such a heater 25 has the advantage of being very economical because it uses seawater as a heat source.
[0030]
Further, the same configuration is applied to the contact between the seawater 10 and the gaseous carbon dioxide. When the seawater 10 and the gaseous carbon dioxide come into contact with each other in the discharge pipe 4, the heater heats this contact portion to generate water. Reduce the occurrence of Japanese food.
[0031]
FIG. 3 is a diagram schematically illustrating a dilution and discharge device according to a second embodiment in which the form of the heater is different. 3, the same parts as those in FIG. 1 are denoted by the same reference numerals. In this embodiment, the heater is installed so as to be able to move up and down. As the heater, any of the heater 21 of the first embodiment and the heater 25 of the second embodiment may be used. The heater 25 of the second embodiment is used. The heater main body 26 of the heater 25 is installed in the discharge pipe 4 so as to be able to move up and down by an appropriate means. Further, the controller 31 mounted on the work boat 3 supplies electric power and a signal to the heater main body 26 via the cable 32 to drive the elevating mechanism, thereby moving the heater main body 26 up and down along the discharge pipe 4. The heater 25 can be moved up and down around a position corresponding to a predicted contact portion between the seawater 10 and the liquid carbon dioxide 6 in advance.
[0032]
Then, the pressure and flow rate of the gaseous carbon dioxide 6 </ b> A fed into the discharge pipe 4 are measured by a pressure gauge and a flow meter 33 provided at the upper end entrance of the discharge pipe 4, and the measurement signal is sent to the controller 31. The controller 31 estimates the pressure fluctuation of the gaseous carbon dioxide 6A sent into the discharge pipe 4 and the position fluctuation of the contact portion between the seawater 10 and the liquid carbon dioxide 6 according to the flow rate, and drives the elevating mechanism to drive the heater main body 26. Is raised and lowered so as to be located at the estimated contact position. By doing so, the heater 25 can always be located at the position of the contact portion between the seawater 10 and the liquid carbon dioxide 6.
[0033]
The heater may be moved up and down through a wire or the like by an elevating mechanism provided on the work boat 3. The position of the contact portion between the seawater 10 and the liquid carbon dioxide 6 may be such that the position where the density of the seawater 10 and the liquid carbon dioxide 6 changes in the vicinity of the contact portion (contact portion position) varies, or It is also possible to detect the change in the position where the refractive index of the light of the carbon 6 changes (the position of the contact portion), respectively.
[0034]
Further, the same configuration is applied to the contact between the seawater 10 and the gaseous carbon dioxide. When the seawater 10 and the gaseous carbon dioxide come into contact with each other in the discharge pipe 4, the heater heats this contact portion to generate water. Reduce the occurrence of Japanese food.
[0035]
The present invention is not limited to the above-described embodiment, but can be implemented with various modifications. For example, the heater may use a chemical reaction as a heat source. In the above-described embodiment, the time when the supply of liquid carbon dioxide to the discharge pipe is started is targeted. However, as described above, even when the supply of liquid carbon dioxide is stopped, the contact portion between the seawater and the liquid carbon dioxide by the heater, the seawater and the gas dioxide The case where the contact part with carbon is heated can also be included.
[0036]
【The invention's effect】
As described above, according to the apparatus for diluting and releasing carbon dioxide into the ocean of the present invention, the contact portion where seawater and liquid carbon dioxide come into contact with each other in a state where seawater is present inside the discharge pipe, The heater heats the contact area where the carbon comes in contact, and suppresses the formation of hydrate at this contact area, preventing the hydrate from blocking the inside of the discharge pipe and obstructing the flow of liquid carbon dioxide Therefore, good discharge of carbon dioxide can be performed.
[0037]
Further, according to the present invention, an appropriate heat source can be provided to the heater. Furthermore, according to the present invention, the heater is moved up and down in accordance with a change in the position of the contact portion between seawater and liquid carbon dioxide, and the position of the contact portion between seawater and gaseous carbon dioxide, so that the heater is always positioned at a position corresponding to the contact portion. Thus, the contact portion can be satisfactorily heated.
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing a dilution and discharge device according to a first embodiment of the present invention.
FIG. 2 is a diagram schematically showing a dilution and discharge device according to a second embodiment.
FIG. 3 is a diagram schematically showing a dilution and discharge device according to a third embodiment.
FIG. 4 is a diagram showing a system for discharging carbon dioxide to the ocean.
FIG. 5 is a diagram schematically showing a device 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 a dilution discharge device.
FIG. 7 is a diagram showing a phase state of carbon dioxide.
[Explanation of symbols]
3. Work boat,
4 ... discharge pipe,
5 ... discharge hole,
6 ... liquid carbon dioxide,
7 ... droplets,
21 ... heater,
22 ... electric heater,
25 ... heater.

Claims (2)

Dilution discharge in which liquid carbon dioxide is fed into the discharge pipe and discharged into the sea from a discharge hole formed in the discharge pipe while running on a ship in which the discharge pipe is suspended in the sea while towing the discharge pipe while tilting the discharge pipe. In the device,
An electric heater is provided at a position corresponding to a contact portion where seawater and carbon dioxide contact with each other in a state where seawater is present inside the discharge pipe, as an electric heater for heating the contact portion. A device for diluting carbon into the ocean. The apparatus for diluting and discharging carbon dioxide into the ocean according to claim 1, wherein the heater is vertically movable.

Images