JP3786595B2 - CO2 deep sea feeding device and clathrate generation method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a carbon dioxide deep sea feeding device that releases recovered carbon dioxide into the sea and dissolves it in seawater. The present invention also relates to a clathrate generation method for controlling generation of a clathrate generated from carbon dioxide and water.
[0002]
[Prior art]
Recently, global warming has become a major problem, and as a result, the concentration of carbon dioxide (CO ₂ ) with a greenhouse effect, which has been pointed out to cause global climate change, has been pointed out. Suppressing the rise has become particularly important. And as one of the countermeasures, the concept of isolating carbon dioxide from the atmosphere over a long period of time has been proposed by collecting carbon dioxide in combustion exhaust gas discharged from thermal power plants and sending it to the ocean. In order to achieve this, it is necessary to prevent new environmental impacts from being caused in the ocean that delivers carbon dioxide.
[0003]
The following two types of systems have been proposed as systems for reducing the influence on the marine environment caused by carbon dioxide feeding. One of them is called the saving type, which is a method of concentrating and storing carbon dioxide in a place such as a pit in the deep sea to limit the area of influence to a specific place and localize it.
[0004]
The other system is a so-called dissolution-diffusion type, which is a method in which carbon dioxide is dissolved in seawater, diluted thinly and diffused widely to suppress an increase in the concentration of carbon dioxide in seawater. This is based on the idea that the concentration of carbon dioxide originally dissolved in seawater only rises to some extent.
[0005]
As a specific method in this dissolution diffusion type, there is a middle-layer dilution discharge method in which the discharge point of carbon dioxide is moved by a ship and carbon dioxide is discharged in the middle layer in the sea. This method will be described with reference to FIG. 9 and FIG. FIG. 9 is an explanatory view schematically showing a middle-dilution discharge system, FIG. 10 (a) is an explanatory view schematically showing a state in which carbon dioxide is discharged and diffused from the input pipe into the sea in the same system, and FIG. FIG. 11B is an enlarged view showing a Z portion in FIG.
[0006]
This middle-layer dilution discharge system liquefies carbon dioxide separated and recovered from combustion exhaust gas in the onshore plant 1, fills the storage tank 2a with the liquefied gas, and transports it to a predetermined sea area by the liquefied gas carrier ship 2, where The liquid carbon dioxide inside the storage tank 2 a is transferred to the storage tank 3 a mounted on the work ship 3. The liquid carbon dioxide has a pressure of 6 atm and a temperature of −55 ° C., for example. FIG. 11 is a diagram showing the phase state of carbon dioxide. As can be seen from this diagram, the conditions of the pressure of 6 atm and the temperature of −55 ° C. are the conditions for obtaining liquid carbon dioxide economically. The work boat 3 is provided with a charging pipe 4 made of a very long steel pipe suspended in the sea at a depth of 2000 m to 2500 m. Liquid carbon dioxide is fed from the storage tank 3a to the charging pipe 4 and is moved vertically to the lower end of the charging pipe 4. It discharges into the sea from a plurality of discharge holes 5 formed side by side in the direction. The work ship 3 moves forward while discharging the liquid carbon dioxide from the hole 5 of the charging pipe 4 into the sea, thereby moving the discharge point of the carbon dioxide without limiting it locally to increase the dilution of the carbon dioxide. Note that the transport ship 2 and the work ship 3 may be different from each other, or may be used both. SL is the sea level.
[0007]
[Problems to be solved by the invention]
Here, when starting the injection of carbon dioxide, it is necessary to first feed carbon dioxide into the input pipe 4 to push out the seawater in the input pipe 4.
However, carbon dioxide tends to produce a clathrate when in contact with seawater. For this reason, as shown in FIG. 12, when the thick sherbet-like clathrate layer 11 is formed between the carbon dioxide layer 9 and the seawater layer 10 in the charging pipe 4, there is a concern that the charging pipe 4 is blocked. ing.
In this way, development of technology that suppresses the generation of clathrate is desired, but on the other hand, development of technology that uses carbon dioxide clathrate as a heat storage material is also expected, which increases the generation amount of clathrate Development of technology to make it happen is also desired.
[0008]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a carbon dioxide deep sea feeding device capable of preventing the closing of the input pipe.
It is another object of the present invention to provide a class rate generation method capable of controlling the generation amount of the class rate.
[0009]
[Means for Solving the Problems]
In view of the above situation, the present inventors diligently studied a substance capable of controlling the generation of clathrate. As a result, the amount of clathrate produced is effective by adding nitrogen (N ₂ ) at the time of clathrate generation. It was found that it was suppressed.
That is, the invention described in claim 1 is a carbon dioxide deep-sea feed device that includes an input pipe extending into the sea and releases carbon dioxide into the sea from an input pipe outlet that opens at the lower end of the input pipe. A nitrogen charging line is provided for feeding nitrogen into the charging tube, which suppresses the amount of clathrate generated when contacting.
Of course, the same effect can be obtained even if air is used as the gas containing nitrogen.
[0010]
The invention according to claim 2 is the carbon dioxide deep-sea feed device according to claim 1, wherein nitrogen gas is supplied into the input pipe from the inlet side of the input pipe through the nitrogen input line. And
[0011]
In this invention, nitrogen can be sent to the seawater level in the input pipe where the clathrate is generated.
[0012]
According to a third aspect of the present invention, in the carbon dioxide deep-sea feed device according to the first aspect, a seawater / nitrogen mixing device for mixing seawater and nitrogen is interposed in the nitrogen input line, and the seawater / nitrogen mixing device The nitrogen-containing seawater generated in step 1 is supplied into the charging pipe from the inlet side of the charging pipe.
[0013]
In the present invention, the seawater in the charging pipe can be replaced with seawater containing nitrogen.
[0014]
According to a fourth aspect of the present invention, in the carbon dioxide deep sea feeding device according to the first aspect, a carbon dioxide / nitrogen mixing device for mixing carbon dioxide and nitrogen is interposed in the nitrogen input line, and the carbon dioxide / A gas mixture of carbon dioxide and nitrogen generated in the nitrogen mixing device is supplied into the input pipe from the inlet side of the input pipe.
[0015]
In the present invention, the gas for extruding the seawater in the input pipe when starting the input of carbon dioxide into the sea can be a mixture of carbon dioxide and nitrogen.
[0016]
According to a fifth aspect of the present invention, in the carbon dioxide deep-sea feed device according to the first aspect, nitrogen is supplied into the input pipe from the outlet side of the input pipe through the nitrogen input line.
[0017]
In this invention, nitrogen can be sent to the seawater surface in the charging pipe by supplying nitrogen from the outlet side of the charging pipe.
[0018]
The invention according to claim 6 is a clathrate production method for producing a clathrate of carbon dioxide by bringing water and carbon dioxide into contact with each other, by adding nitrogen to at least one of the water and carbon dioxide. Further, the generation amount of the clathrate is suppressed.
[0019]
Thus, although the production of clathrate is suppressed by nitrogen, the present inventors have also found that the amount of clathrate produced is effectively increased by adding iodine during the production of clathrate.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of the present invention will be described with reference to the drawings. In addition, about the structure same as the said prior art, the same code | symbol is used and the description is abbreviate | omitted.
What is shown in FIG. 1 is a carbon dioxide deep sea feeding device according to this example. In the figure, reference numeral 4 is an input pipe, 20 is a CO ₂ pipe, and 21 is an N ₂ pipe as a nitrogen input line. The N ₂ pipe 21, N ₂ is adapted to be fluidized by a pump (not shown) or the like. The CO ₂ pipe 20 and the N ₂ pipe 21 supply CO ₂ and N ₂ to the inlet 4 a side of the input pipe 4, respectively, and valves 22 and 23 are interposed, respectively.
[0022]
Next, a procedure for introducing carbon dioxide into the sea using the carbon dioxide deep-sea feed device configured as described above will be described.
First, as shown in FIG. 2 (a), when the input pipe 4 is extended into the sea, the seawater 30 flows into the input pipe.
CO ₂ is supplied into the input pipe through the CO ₂ pipe (FIG. 2 (b)). In this state, the pipe is divided into seawater 30 and gas phase CO ₂ 31G. As the CO ₂ is supplied, the sea level 30a is gradually lowered. When the seawater surface 30a in the inlet pipe 4 becomes deeper than the CO ₂ saturated vapor pressure equivalent depth L at the inlet pipe ambient temperature, the CO ₂ is liquefied and becomes liquid phase CO ₂ 31L (FIG. 2 (c)). . Since the liquefied CO ₂ 31L is not mixed with the seawater 30, it is separated into the gas phase CO ₂ 31G, the liquid phase CO ₂ 31L, and the seawater 30 in this order from the top.
When the supply of CO ₂ is continued, all the seawater 30 is discharged from the input pipe 4 (FIG. 2 (e)). When the supply of CO ₂ is further continued, the CO ₂ 31G and 31L in the charging pipe 4 gradually approaches the CO ₂ temperature in the storage tank 3a, and all of the charging pipe 4 becomes CO ₂ 31L in the liquid layer, and the steady charging is performed. Start (FIG. 2 (h)).
[0023]
Now, when carbon dioxide comes into contact with seawater, a clathrate is generated. To suppress the occurrence of clathrate, the supply start before the CO ₂ in the present embodiment (state of FIG. 2 (a)), and supplies a N ₂ into the feeding pipe 4 by opening the valve 23. As a result, N ₂ is dissolved in the seawater 30 near the seawater surface 30a. Thereafter, the valve 22 is opened to supply CO ₂ . Since N ₂ is dissolved in the vicinity of the sea surface 30a where the clathrate is generated as described above, the formation of clathrate is suppressed by the action of N ₂ , and the film-like clathrate layer 35 as shown in FIG. Only formed. Since the clathrate layer 35 can be easily crushed, the closing of the charging pipe 4 is prevented.
Note that the inside of the charging pipe 4 may be sufficiently pressurized with N ₂ and then CO ₂ may be charged.
[0024]
Next, the procedure at the time of stopping CO ₂ charging will be described with reference to FIG.
First, the valve 22 of the CO ₂ supply pipe is closed. As shown in FIG. 4 (a), the liquid phase CO ₂ 31L filled in the charging pipe 4 is heated and vaporized by the surrounding seawater, and the liquid level of the liquid layer CO ₂ 31L is gradually lowered (FIG. 4). 4 (b), (c)). When the liquid level drops to a depth equivalent to the CO ₂ saturated vapor pressure at the ambient temperature of the input pipe 4, an equilibrium state is reached (FIG. 4 (d)). Then, the vaporized CO ₂ 31G in the charging pipe 4 is recovered from the charging pipe or released into the atmosphere. As a result, the sea level 30a gradually rises, and the stop operation is completed when the entire input pipe 4 is filled with the sea water 30.
[0025]
Even when the charging is stopped, a clathrate is generated due to the contact between carbon dioxide and seawater, similar to the start of charging. In this example, the valve 23 of the N ₂ piping is opened before the CO ₂ charging stop, and the charging tube 4 is filled with liquid phase CO ₂ (N ₂ rich CO ₂ ) in which N ₂ has dissolved.
That is, when seawater flows into the input pipe 4 (FIG. 4 (e) → (h)), N ₂ is dissolved in CO ₂ in contact with seawater. For this reason, the generation of clathrate is suppressed by the action of N ₂ , and only the film-like clathrate layer 35 is formed as shown in FIG. Since this clathrate layer 35 can be easily pulverized, the closing of the charging tube 4 is prevented.
[0026]
As described above, in the carbon dioxide deep sea feeding device of this example, the generation of the clathrate can be suppressed by supplying N ₂ into the input pipe 4 and the input pipe 4 can be prevented from being blocked.
[0027]
Next, a second embodiment of the present invention will be described. In addition, about the structure same as the said embodiment, the same code | symbol is used and the description is abbreviate | omitted.
In FIG. 5, the code | symbol 40 is seawater piping which supplies seawater in an injection pipe. 41, together to merge the N ₂ pipe and seawater pipes, a seawater-nitrogen mixing device are dissolved in the seawater sent from seawater piping N ₂ sent from the N ₂ pipe. Reference numeral 42 denotes a valve interposed in a pipe for supplying seawater containing nitrogen mixed by the seawater / nitrogen mixing device 41 to the input pipe 4.
[0028]
Next, a charging start procedure and a charging end procedure in the case where the carbon dioxide deep sea feeding device of the present example is used will be described. Since the CO ₂ input / discharge procedure itself is the same as that shown in FIGS. 2 and 4, the description thereof will be omitted, and only N ₂ input will be described.
In the CO ₂ charging start procedure, the valve 42 is opened before CO ₂ charging starts (the state shown in FIG. 2A in which the charging pipe 4 is filled with seawater), and the seawater in which N ₂ is dissolved is added to the charging pipe 4. Keep it inside. That is, the seawater filled in the charging pipe 4 is replaced with seawater rich in N ₂ .
After that, as shown in FIG. 2 (b), the introduction of CO ₂ is started. Since N ₂ is dissolved in the seawater, the amount of clathrate generated on the sea surface is suppressed, and only the membrane-like clathrate layer 35 (see FIG. 3) is formed. Since this clathrate layer can be easily crushed, blockage of the input pipe 4 is prevented.
In the CO ₂ charging / stopping procedure, after reaching the equilibrium state of FIG. 4 (d), the valve 42 is opened to discharge CO ₂ while supplying N ₂ rich seawater into the charging pipe 4. Thereby, the production amount of the clathrate formed on the seawater surface can be suppressed similarly to the above, and the closing of the charging pipe 4 is prevented.
[0029]
Next, a third embodiment of the present invention will be described. In addition, about the structure same as the said embodiment, the same code | symbol is used and the description is abbreviate | omitted.
6, reference numeral 45, as well to merge the CO ₂ that is supplied from the N ₂ and CO ₂ pipe 20 supplied from the N ₂ pipe 21, carbon dioxide, nitrogen supplied to the feeding pipe 4 these as mixture It is a mixing device. 46 is a valve interposed in a pipe for supplying the mixed gas mixed in the carbon dioxide / nitrogen mixing device 45 to the input pipe 4, and 47 is a valve for opening / closing the supply of N _{2 to} the carbon dioxide / nitrogen mixing device. is there.
[0030]
Next, a charging start procedure and a charging end procedure in the case where the carbon dioxide deep sea feeding device of the present example is used will be described. Since the CO ₂ input / discharge procedure itself is the same as that shown in FIGS. 2 and 4, the description thereof will be omitted, and only N ₂ input will be described.
In the CO ₂ injection start procedure, when CO ₂ is supplied into the input pipe 4 and the seawater in the input pipe 4 is pushed out (FIGS. 2B to 2E), the valve 47 of the N ₂ pipe is opened. Then, CO ₂ mixed with N ₂ is supplied to the charging pipe. Since N ₂ is mixed with CO ₂ , the amount of clathrate formed on the seawater surface is suppressed, and only the membrane-like clathrate layer 35 (see FIG. 3) is formed. Since the clathrate layer 35 can be easily crushed, the closing of the charging pipe 4 is prevented.
After all the seawater in the input pipe is removed, the valve 47 of the N ₂ pipe is closed, and only CO ₂ is supplied to the input pipe to send CO ₂ into the sea.
In the CO ₂ charging / stopping procedure, the valve 47 of the N ₂ pipe is opened prior to CO ₂ charging / stopping, and the mixture of N ₂ and CO ₂ is filled in the charging pipe 4.
As a result, even when seawater flows into the input pipe 4, the generation of clathrate is suppressed by the action of N ₂ contained in CO ₂ in contact with seawater, and the membrane-like clathrate layer 35 (FIG. 3) Only see). Since this clathrate layer 35 can be easily pulverized, the closing of the charging tube 4 is prevented.
[0031]
Next, a fourth embodiment of the present invention will be described. In addition, about the structure same as the said embodiment, the same code | symbol is used and the description is abbreviate | omitted.
In FIG. 7, reference numeral 48 denotes an N ₂ pipe as a nitrogen input line, the end of which opens to the outlet 4 b side of the input pipe 4, and N ₂ is supplied into the input pipe 4 from the outlet 4 b side. It has become. Reference numeral 49 denotes a valve for opening and closing the supply of N ₂ .
[0032]
Next, a charging start procedure and a charging end procedure in the case where the carbon dioxide deep sea feeding device of the present example is used will be described. Since the CO ₂ input / discharge procedure itself is the same as that shown in FIGS. 2 and 4, the description thereof will be omitted, and only N ₂ input will be described.
In CO ₂ turned start procedure supplied, when extruding the seawater in the CO ₂ feeding pipe 4 is supplied to the injection tube 4 (see FIG. 2 (b), etc.), the CO ₂ from the feeding pipe 4 inlet 4a At the same time, the valve 49 of the N ₂ pipe is opened and N ₂ is supplied from the outlet 4 b side of the input pipe 4. In the charging pipe 4, the N ₂ bubbles rise to the sea surface 30a, so that the formed clathrate is crushed, and the generation of clathrate itself is suppressed by the action of N ₂ .
After all the seawater 30 in the input pipe 4 is removed, the valve 49 of the N ₂ pipe is closed, and only CO ₂ is supplied to the input pipe 4 to send CO ₂ into the sea.
In the CO ₂ charging / stopping procedure, the valve 49 of the N ₂ pipe is opened prior to CO ₂ charging / stopping, and a mixture of N ₂ and CO ₂ is filled in the charging pipe.
As a result, even when CO ₂ in the input pipe 4 is discharged and seawater flows into the input pipe 4, the generation of clathrate is suppressed by the action of N ₂ contained in CO ₂ in contact with seawater. Only the film-like clathrate layer 35 (see FIG. 3) is formed. Since this clathrate layer 35 can be easily pulverized, the closing of the charging tube 4 is prevented.
Note that the N ₂ pipe 48 may be provided inside the charging pipe 4 as shown in FIG.
[0033]
As described above, by adding N ₂ to at least one of seawater and carbon dioxide, the production amount of clathrate can be suppressed and the closing of the injection pipe 4 can be prevented.
On the other hand, by adding iodine instead of nitrogen, the amount of clathrate produced can be increased compared to the case where no iodine is added.
In this case, it is possible to use a device similar to that in each of the above embodiments. That is, iodine may be supplied to the N ₂ pipe in each of the above devices. In this case, CO ₂ is not fed into the sea.
The generated clathrate is considered to be used as a heat storage material, for example.
[0034]
In the first to fourth embodiments, nitrogen is used to suppress the generation of clathrate. However, since air also contains nitrogen, air is supplied to the input pipe instead of nitrogen. Also good.
Further, as a device for generating the clathrate, it is not necessary to be a carbon dioxide deep sea feeding device as described above, and it is needless to say that it may be generated in a factory or the like, for example.
[0035]
【The invention's effect】
As described above, the following effects can be obtained in the present invention.
According to the invention of claims 1 to 5, by the addition of N _2, it is possible to suppress the production of the clathrate to prevent blockage of the injection tube.
According to the sixth aspect of the present invention, the amount of carbon dioxide clathrate produced can be suppressed by adding nitrogen.
[Brief description of the drawings]
FIG. 1 is a view showing a charging pipe of a carbon dioxide deep sea feeding device shown as a first embodiment of the present invention.
FIG. 2 is a diagram showing a carbon dioxide input start procedure.
FIG. 3 is a diagram showing a state of clathrate generation in the input pipe in the present embodiment.
FIG. 4 is a diagram showing a procedure for stopping the introduction of carbon dioxide.
FIG. 5 is a view showing an input pipe of a carbon dioxide deep sea feeding device shown as a second embodiment of the present invention.
FIG. 6 is a view showing an input pipe of a carbon dioxide deep sea feeding device shown as a third embodiment of the present invention.
FIG. 7 is a view showing an input pipe of a carbon dioxide deep sea feeding device shown as a fourth embodiment of the present invention.
FIG. 8 is a diagram showing a modification of the embodiment.
FIG. 9 is a diagram schematically showing a system for introducing carbon dioxide into the sea.
FIG. 10 is a view showing an input pipe of a carbon dioxide deep sea feeding device.
FIG. 11 is a diagram showing a phase state of carbon dioxide.
FIG. 12 is a view showing a clathrate generated in a charging pipe in a conventional carbon dioxide deep sea feeding device.
[Explanation of symbols]
4 Input pipe 4a Input pipe inlet 4b Input pipe outlet 21, 48 N ₂ piping (nitrogen input line)
41 Seawater / nitrogen mixer 45 Carbon dioxide / nitrogen mixer

Claims (6)

In a carbon dioxide deep sea feeding device that includes an input pipe extending into the sea and releases carbon dioxide into the sea from an input pipe outlet that opens at the lower end of the input pipe.
A carbon dioxide deep-sea feed device characterized in that a nitrogen feed line is provided for feeding nitrogen into the feed pipe to suppress the amount of clathrate produced when carbon dioxide comes into contact with seawater. In the carbon dioxide deep sea feeding device according to claim 1,
A carbon dioxide deep-sea feed device, wherein nitrogen gas is supplied into the charging pipe from the inlet side of the charging pipe through the nitrogen charging line. In the carbon dioxide deep sea feeding device according to claim 1,
A seawater / nitrogen mixing device that mixes seawater and nitrogen is interposed in the nitrogen input line, and the seawater containing nitrogen generated in the seawater / nitrogen mixing device is supplied into the input tube from the inlet side of the input tube. Carbon dioxide deep sea feeding device characterized by being made. In the carbon dioxide deep sea feeding device according to claim 1,
A carbon dioxide / nitrogen mixing device that mixes carbon dioxide and nitrogen is interposed in the nitrogen charging line, and a mixture of carbon dioxide and nitrogen generated in the carbon dioxide / nitrogen mixing device is an inlet of the charging tube. Carbon dioxide deep-sea feed device, characterized in that the carbon dioxide is fed into the input pipe from the side. In the carbon dioxide deep sea feeding device according to claim 1,
A carbon dioxide deep-sea feed device, wherein nitrogen is supplied into the charging pipe from the outlet side of the charging pipe through the nitrogen charging line. In a clathrate production method for producing a carbon dioxide clathrate by contacting water and carbon dioxide,
A method for producing a clathrate, wherein the amount of clathrate produced is suppressed by adding nitrogen to at least one of water and carbon dioxide.

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