JP4363537B1 - Deep carbon settlement system and method of liquid carbon dioxide - Google Patents

Abstract

An economical deep sea subsidence system and method for allowing a storage device containing liquid carbon dioxide to sink without rupturing until reaching the sea bottom and enabling long-term storage at the sea bottom.
Carbon dioxide, which is vaporized to reach the deep sea and increases the internal pressure, is released into the sea outside the storage container 2, and the storage container 2 is sunk to the sea floor while suppressing the release amount as much as possible. In order to suppress the discharge amount, at least until the critical depth is reached, the storage container 2 is covered with a protective container 4 having either one or both of heat insulation and pressure resistance and is allowed to sink. The subsidence speed of the storage container 2 is relatively high until reaching the critical depth, and is relatively low at a depth exceeding the critical depth. In this case, the high-speed settlement is caused by the action of the relatively heavy weight 25 or the driving force 33 drawn into the sea, so that the low-speed settlement is caused by the action of the relatively light weight 25, the natural fall of the storage container 2, or It is obtained by using any one of the reduction umbrellas 26 of the storage device.
[Selection] Figure 4

Description

  TECHNICAL FIELD The present invention relates to a liquid carbon dioxide deep-sea subsidence system and a deep-sea subsidence method that efficiently and safely sinks liquid carbon dioxide obtained on the ground surface and the sea to the deep sea.

  Carbon dioxide (carbon dioxide) is a major cause of global warming, and the reduction of carbon dioxide concentration is an important issue to be addressed on a global scale. Nevertheless, the current situation is that the international community has not yet been able to find a powerful solution because of the thoughts of each country. In addition, if technological innovation advances in the future, it is highly conceivable that an era in which carbon dioxide, which is now hated, will be effectively utilized in technical fields such as synthetic resins will come. Therefore, for the time being, if we can build a system that collects carbon dioxide, which causes environmental damage, from the atmosphere, stores it in one place for a long time, and collects and uses it when needed in the future, it will contribute to the earth and humankind. Bring.

  Focusing on the property of carbon dioxide that maintains a liquid state under high pressure even at room temperature, a technique for long-term storage at the sea floor using high water pressure that is easily obtained in the deep sea is disclosed (for example, Patent Document 1). reference.). However, many technical problems to be solved still remain to realize this. To maintain liquid carbon dioxide in a liquid state at room temperature, a high pressure of 50 atm or more is required. Even if liquid carbon dioxide can be sealed in a container under high pressure on the ground, In order to safely sink to the sea floor, an expensive container such as a high pressure resistant special alloy is required. In addition, there is a problem that long-term storage cannot be ensured with iron alloys or the like on the sea floor where the corrosive action by seawater is severe.

  Conversely, in order to maintain liquid carbon dioxide as a liquid at atmospheric pressure, it is necessary to maintain a low temperature of about −50 ° C. For this reason, even if liquid carbon dioxide can be sealed in a container at low temperatures on the ground, a technique such as covering it with a special heat insulation case is necessary to remove it and safely sink it to the sea floor while preventing vaporization. Is required. Although it depends on the region, the seawater temperature is limited to 10 ° C inside and outside at the surface layer, and 3 to 5 ° C inside and outside even when it sinks 100 m, and it is not easy to maintain the low temperature as described above during subsidence. . If the temperature rises even a little, vaporization of liquid carbon dioxide inside the container is unavoidable, and the internal pressure of the container increases due to vaporization, which causes the same pressure resistance problem as described above. There is also a problem of long-term storage at the sea floor where the corrosive action is severe.

  In any case, it is technically difficult to expect a perfect heat insulation effect that maintains a low temperature of −50 ° C. or lower in the sea. In order to reliably sink liquid carbon dioxide to the sea floor of 500 m or less, it is Development of containers with sufficient corrosion resistance is inevitable. However, it is difficult to find an inexpensive material that has both of these properties. In Patent Document 1, it is disclosed that liquid carbon dioxide is filled in a “bag-like container”, and specifically, an experiment for simulating a deep sea of 1000 m as a fluororesin-like bag-like container is disclosed. Alternatively, it is stated that materials such as polypropylene and polyethylene can be used. However, with these materials, even if the effects of corrosion resistance due to the fixation of liquid carbon dioxide in the deep sea and the use of synthetic resins are recognized, the countermeasures against the increase in the internal pressure of the container due to the temperature rise during subsidence are completely silent. ing. Therefore, it is very doubtful whether the materials and means disclosed in this document can be overcome by the high pressure in the settlement process.

  From the above, although it seems that the best way to obtain the high pressure necessary to fix and store liquid carbon dioxide at room temperature economically and easily is to use deep seawater pressure, it is necessary to realize this. At the time of subsidence, the response to the pressure increase caused by the vaporization or sublimation of carbon dioxide due to the temperature rise until reaching the bottom of the sea is now a major bottleneck. Although it is feasible if a high pressure vessel is used, in this case, economy becomes a bottleneck, and it cannot be said that the problem of corrosion resistance in long-term storage on the sea floor can be solved. In other words, there is a need for a container that can withstand pressure and does not rupture, and a system that can safely sink to the deep sea using the container, but it is currently difficult to implement due to the use of advanced technology and high cost. It has become.

  Therefore, the invention of the present application is an economical liquid carbon dioxide that can withstand a pressure increase due to temperature rise until reaching the bottom of the sea in the deep subsidence of liquid carbon dioxide without causing rupture and can be stored for a long time on the sea bottom. It aims to provide a deep sea subsidence system and method.

  The present invention releases carbon dioxide that evaporates in a liquid carbon dioxide storage container to increase the internal pressure before reaching the deep sea, and sinks the storage container to the sea floor while suppressing the release amount as much as possible. The above-mentioned problem is solved by taking the measures to be performed, and specifically includes the following contents.

  That is, in one aspect according to the present invention, the storage container storing the liquid carbon dioxide reaches at least the deep sea at a critical depth that is a water pressure sufficient to prevent vaporization of the liquid carbon dioxide in the storage container. A method of deep subsidence of liquid carbon dioxide that is submerged without being ruptured by internal pressure due to vaporized liquid carbon dioxide, and the internal pressure of the storage container increased by the vaporized carbon dioxide until reaching a critical depth. The present invention relates to a method of sinking a storage container while discharging at least a part of carbon dioxide vaporized before reaching a limit pressure for rupturing the liquid into the sea outside the storage container.

  At least until the critical depth is reached, it is desirable to cover the storage container with a protective container having either one or both of heat insulation and pressure resistance and sink. Further, it is desirable that the storage container sinks at a relatively high speed until reaching the critical depth and at a relatively low speed at a depth exceeding the critical depth. High-speed subsidence up to the critical depth is due to the use of a relatively heavy weight or a driving force drawn into the sea, so low-speed subsidence at a depth exceeding the critical depth is a relatively light weight. It can be obtained by using any of the above actions, the natural fall of the storage container, or the speed reduction umbrella of the storage container.

  The present invention further provides a carbon dioxide seafloor storage method for separating carbon dioxide in the atmosphere into liquid carbon dioxide, storing the liquid carbon dioxide in a storage container, and sinking and storing the carbon dioxide in the seabed. The method also includes a method for storing liquid carbon dioxide on the seabed, wherein the storage container is submerged on the seabed by such a method.

  Next, another aspect of the present invention is a liquid carbon dioxide deep-sea subsidence system in which a storage container that similarly stores liquid carbon dioxide is submerged without rupturing and is softly landed on the sea floor, and is a liquid manufactured on the ground. A marine facility that transports carbon dioxide or produces liquid carbon dioxide by itself, a storage container that stores liquid carbon dioxide, and a subsidence guide mechanism that sinks the storage container to at least a critical depth, It has a degassing mechanism that releases at least a portion of the carbon dioxide vaporized before the internal pressure due to the vaporization of the liquid carbon dioxide reaches the limit pressure for rupturing the storage container. It has flexibility that can be deformed according to the water pressure received and corrosion resistance to seawater, and the subsidence guide mechanism is a weight that pulls the storage container into the sea It comprises about deep sea subsidence system according to claim.

  The subsidence guide mechanism may further include a protective container that covers the storage container and has either one or both of heat insulation and pressure resistance, and releases the storage container to a critical depth. In addition, the protective container releases internal gas when the internal pressure of the protective container reaches a predetermined value, and adjusts the internal / external pressure to introduce external seawater when the water pressure outside the container reaches a predetermined value. A mechanism can be provided.

  Still another aspect of the present invention is a liquid carbon dioxide storage container that stores liquid carbon dioxide, sinks in the sea without being ruptured by internal pressure due to vaporized liquid carbon dioxide, and softly lands on the seabed at a speed that does not rupture. A gas venting mechanism for releasing at least a part of the vaporized carbon dioxide to the outside before the internal pressure due to the vaporization of the liquid carbon dioxide reaches a limit pressure for rupturing the storage container. It is related with the liquid carbon dioxide storage container characterized by having the flexibility which can change according to the water pressure received in the deep sea by weight loss by, and the corrosion resistance to seawater.

  The liquid carbon dioxide storage container may further include a speed reduction mechanism that reduces the settlement speed after the critical depth is exceeded. The speed reduction mechanism can be either a resistance umbrella opening / closing mechanism or a weight separation mechanism.

  The present invention is designed for storage by storing carbon dioxide in a cryogenic liquid (or solid) state in a container for storage at the bottom of the sea, and submerging it while releasing the vaporization (sublimation) gas pressure inside the container for storage in the course of submergence. Since the container can be made of a low-strength, low-pressure-resistant material and structure, there is an effect that the liquid carbon dioxide can be stored on the seabed economically. Also, incidental devices such as protective containers can be saved and reused by collecting and reusing them. Furthermore, by implementing the present invention, the concentration of carbon dioxide in the atmosphere can be reduced, and the effect of improving environmental problems on a global scale is achieved.

It is explanatory drawing which shows the outline | summary of the deep-water subsidence system of the liquid carbon dioxide concerning embodiment of this invention, and the method. It is the perspective view and partial sectional view which show the outline | summary of the liquid carbon dioxide storage container used for embodiment shown in FIG. It is explanatory drawing which shows the outline | summary of the deep sea subsidence system of the liquid carbon dioxide which concerns on the other aspect of embodiment shown in FIG. 1, and the method. It is explanatory drawing which shows the outline | summary of the deep-sea subsidence system of the liquid carbon dioxide which concerns on other embodiment of this invention, and the method. It is a fragmentary sectional side view which shows the outline | summary of the storage container and protection container which are used for embodiment shown in FIG. It is a fragmentary sectional side view which shows the outline | summary of the other storage container and protection container used for embodiment shown in FIG. It is a perspective view which shows the storage container used for the liquid carbon dioxide deep sea subsidence system which concerns on other embodiment of this invention, and the method.

  A deep sea settlement system and a deep sea settlement method of liquid carbon dioxide according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows the outline. In FIG. 1, the deep sea settlement system according to the present embodiment includes a marine facility (specifically, a work ship) 1, a liquid carbon dioxide storage container 2, and a settlement guide mechanism 3. The offshore facility 1 has a facility for producing liquid carbon dioxide in the designated sea area by itself or a facility necessary for transporting the liquid carbon dioxide produced in another facility on the ground or the like to the designated sea area. The production of liquid carbon dioxide is already known in the prior art. For example, only carbon dioxide is separated from nitrogen and other components in the air and liquefied using low temperature or high pressure or both. As can be seen from the phase diagram of carbon dioxide, carbon dioxide liquefies at 0 ° C. and about 50 atm. The liquefied carbon dioxide is put into a low-temperature / high-pressure storage tank (not shown) provided in the offshore facility 1 and injected into the liquid carbon dioxide storage container 2 in the designated subsidized sea area.

  Carbon dioxide is also known to have a subtle change in state between liquid and solid depending on temperature and pressure conditions, and to undergo sublimation from the solid. Therefore, in the present specification, the term “liquid” is not limited to a liquid in a strict sense unless otherwise specified, and includes a solid state as long as there is no problem. Similarly, the term “vaporization” also includes sublimation unless otherwise specified.

  FIG. 2 shows an outline of the liquid carbon dioxide storage container 2 (hereinafter also simply referred to as “storage container 2”). The capacity of the storage solution 2 is preferably large in order to efficiently suppress liquid carbon dioxide subsidence while suppressing loss due to gas release, but the larger the capacity, the greater the handling in the marine facility 1 (for example, injection, lifting, injection into the sea, (Settlement) becomes difficult, and the strength of the container body is also required. In the present embodiment, one having a capacity of 1 ton is used. The shape of the liquid carbon dioxide storage container 1 is arbitrary. In the example of FIG. 2, the liquid carbon dioxide storage container 1 has a substantially cubic shape, but is not limited thereto. For example, as will be described later, a truncated cone and a truncated pyramid are also preferable, and a streamlined shape such as a teardrop shape or a spherical shape may be considered to increase the sinking speed.

  The body body 21 of the liquid carbon dioxide storage container 2 is provided with a liquid carbon dioxide inlet 22, and a lid 24 with a degassing mechanism is attached to the inlet 22 to seal it after the liquid carbon dioxide is injected. An outline of the lid 24 is shown in a circle in FIG. The degassing mechanism 23 is a kind of safety valve, and when the liquid carbon dioxide stored in the storage container 2 is vaporized and the internal pressure is increased, the degassing mechanism 23 (valve) is opened, and at least the vaporized carbon dioxide in the inside is opened. A part is discharged to the outside (in the sea) as indicated by an arrow in the circle, and the liquid carbon dioxide storage container 2 is prevented from rupturing due to an increase in internal pressure. The limit pressure that triggers opening of the valve can be arbitrarily set according to the pressure resistance of the liquid carbon dioxide storage container 2. As will be described later, the higher the limit pressure is, the higher the storage efficiency of liquid carbon dioxide is. For this purpose, it is necessary to increase the pressure resistance of the storage container 2 accordingly. In the example shown in FIG. 2, a gas venting mechanism 23 is provided in the lid 24, which is preferable because the structure is simplified, but separate from the lid 24 by providing another opening in the storage container 2 itself. A gas venting mechanism 23 may be arranged.

  The liquid carbon dioxide storage container 2 is preferably further provided with a sinking weight 25. This is a weight for securing an appropriate settlement speed when the storage container 2 is separated from the settlement guide mechanism 3 and sinks to the seabed. The ideal landing speed is a speed at which a person walks. If the speed is higher than that, the storage container 2 may burst due to an impact at the time of landing, and the weight 25 is set in consideration of this. If the container 2 itself is made of metal and can be secured to meet the above-mentioned conditions, it is not necessary to provide a sinking weight 25 separately.

  Since the liquid carbon dioxide storage container 2 according to the present invention includes the gas venting mechanism 23, the storage container 2 itself is not required to have special pressure resistance. As will be described later, it is necessary to withstand high pressure in the deep sea, but in this case, it is sufficient to have enough flexibility to withstand the dent of the container corresponding to the reduced amount of released carbon dioxide, and this reduced amount is compressed. After this is done, the internal liquid carbon dioxide and the external seawater pressure are in an equilibrium state, so no pressure acts on the storage container 2 itself. Therefore, the liquid carbon dioxide storage container 2 according to the present invention is not required to have high pressure resistance as considered in the prior art, and has sufficient corrosion resistance to withstand long-term seafloor storage. It will be good. As materials used, first, synthetic resins such as polyethylene and nylon are conceivable. In the environment where light does not reach in the deep sea, weather resistance to polycarbonate and polypropylene is not required. In addition, the price is high, but aluminum coated with stainless steel or vinyl chloride can also be used.

  Returning to FIG. 1, the settlement guide mechanism 3 includes a guide wire 31 and a weight 32. In order to preserve liquid carbon dioxide at the sea bottom, it is necessary to sink to a deep sea of about 50 atm or more and about 500 m or more. Therefore, the guidewire 31 must have a length that extends to a depth of at least 500 m. A weight 32 is attached to the tip of the guide wire 31, and the liquid carbon dioxide storage container 2 is attached to the guide wire 31 or the weight 32. In order to minimize the amount of carbon dioxide released during the sinking, it is desirable to sink the storage container 2 as fast as possible. For this purpose, the weight 32 is preferably heavier, but there is a problem in handling, and an appropriate weight is selected. In this embodiment, a 500 kg weight is used. In addition, although the weight 32 is arrange | positioned under the storage container 2 in the example of illustration, in order to pull the storage container 2 with the weight 32 and to sink in the sea, such arrangement | positioning is preferable. At this time, the weight 32 and the liquid carbon dioxide storage container 2 are separated from each other by, for example, using two guide wires 31 and attaching the other one to the weight 32 and moving the other one upward at a predetermined depth. The method of returning to can be considered. For separating the storage container 2 from the guide wire 31, a known technique such as a pressure sensitive unlocking mechanism can be used.

  The liquid carbon dioxide deep sea settlement system according to the present embodiment configured as described above operates as follows. First, the offshore facility 1 moves to the indicated sea area where the liquid carbon dioxide storage container 2 should be submerged. Liquid carbon dioxide produced or transported in the offshore facility 1 is injected into the liquid carbon dioxide storage container 2. A lid 24 is closed to the container 2 into which liquid carbon dioxide has been injected. In this embodiment, the lid 24 is attached to the guide wire 31 of the subsidence guide mechanism 3, and is used in the sea together with the subsidence guide 3 using the crane 11 of the offshore equipment 1. It is thrown into.

  The storage container 2 is exposed to room temperature and atmospheric pressure after the liquid carbon dioxide is injected and before it is dropped into the sea. This causes some of the liquid carbon dioxide inside to begin to vaporize, which increases the pressure inside the container. When the above-mentioned limit pressure at which the gas venting mechanism 23 operates is reached, the valve of the gas venting mechanism 23 is opened and carbon dioxide is released to the outside of the container. This is the same even after being dropped into the sea. The vaporization of carbon dioxide continues by touching the relatively high temperature near the water surface, and the carbon dioxide escapes into the seawater through the valve 23. Therefore, it is preferable to bring the liquid carbon dioxide storage container 2 to the deep sea of low temperature and high pressure as soon as possible to increase the storage efficiency, and the weight 32 performs this function as described above. In addition, since the heat of vaporization is taken when the liquid carbon dioxide is vaporized, a phenomenon in which a part of the liquid carbon dioxide is solidified and transformed into solid carbon dioxide, which is further sublimated can be seen.

  The amount of carbon dioxide released in the middle of subsidence decreases for a while due to water pressure as it sinks deep into the sea floor, reaches about 500 m deep sea and is sealed by external water pressure to prevent vaporization. In this specification, the water pressure at this time is called “critical water pressure”, and the depth in the sea at this time is called “critical depth”. In the process of subsidence after exceeding the critical depth, liquid carbon dioxide does not vaporize and the internal volume does not decrease. Further, since the water pressure by seawater and the pressure of liquid carbon dioxide inside the container are balanced inside and outside the storage container 2, the storage container 2 is deformed into a state where the container is recessed by the reduced amount of carbon dioxide released by vaporization. However, no pressure is applied to the storage container 2 itself.

  In order to reduce the amount of carbon dioxide released as much as possible until the critical water pressure is reached, it is preferable to use the weight 32 to sink as fast as possible, but this is not necessary after reaching the critical water pressure. Therefore, after reaching the critical water pressure, the storage container 2 can be separated from the settlement guide mechanism 3 and can be allowed to sink under its own weight. The subsidence rate at this time is selected at a speed at which the storage container 2 does not rupture due to impact when landing on the seabed. In the state after landing, the liquid carbon dioxide can be fixed and stored in the storage container 2 in the deep sea, and can be left in this state in the state until it is required in the future.

  With regard to the recovery of the liquid carbon dioxide storage container 2 stored for a long time in this way, it is out of the spirit of the present invention related to the deep sea subsidence technology, but the designated storage area is specified, and the discovery is made by using a deep sea camera or the like. Easy. For recovery, use of a deep-sea boat, use of a heat-insulating / pressure-resistant shuttle container, which will be described later in detail, may be considered. However, the present invention does not necessarily require collection. Even when it is not recovered, it can play the important role of fixing the carbon dioxide on the sea floor to reduce the carbon dioxide content in the atmosphere and prevent environmental destruction.

  FIG. 3 shows a liquid carbon dioxide deep sea subsidence system according to another embodiment of the present embodiment. In this deep sea subsidence system, a motor 33 is attached to a weight 32 submerged in the sea with respect to FIG. Accordingly, the container 2 attached to the guide wire 31 is forcibly sunk by rotating the endless guide wire 31 without repeatedly sinking and collecting the weight 32. In the illustrated example, the motor 33 is attached to the underwater weight 32 side, but a drive device such as a motor may be attached to the crane 11 side of the offshore facility 1. According to this aspect, it is not necessary to sink and collect the weight 32 each time, so that the storage container 2 can sink more efficiently. Furthermore, not only one guide wire 31 but also, for example, a plurality of storage containers 2 can be attached at every 50 m, every 100 m, and the like, and can be sunk at the same time.

  Next, a liquid carbon dioxide deep sea settlement system and a deep sea settlement method according to a second embodiment of the present invention will be described with reference to the drawings. FIG. 4 shows an outline of the liquid carbon dioxide deep sea settlement system and the deep sea settlement method according to the present embodiment. In the figure, the same elements as those of the previous embodiment are denoted by the same reference numerals. In the present embodiment, a protective container 4 that covers the storage container 2 is further provided. In the illustrated example, the protective container 4 is provided with an open / close door 42, and the open / close door 42 is in a closed state from underwater dropping to a predetermined depth, and the storage container 2 is stored in the protective container 4. Yes. The opening / closing door 42 is opened to a predetermined depth, specifically, a critical depth (about 500 m) at which the liquid carbon dioxide in the storage container 2 is not vaporized by the action of water pressure, and the storage container 2 is released to the seabed. It is configured to fall naturally. After the discharge, the protective container 4 is pulled up and can be used repeatedly.

  Further, in the illustrated example, the anchor wire 5 having the anchor 51 at the tip thereof is lowered from the offshore facility 1, and the protective container 4 and the storage container 2 are respectively guided along the anchor wire 5 into the sea. In particular, since the storage container 2 is guided by the anchor wire 5 until it is discharged from the protective container 4 and landed on the seabed, when the storage container 2 is sunk in a narrow range, or the flow of the tide in the deep sea It is effective when submerging into the early sea area.

  FIG. 5 shows the relationship between the protective container 4 and the liquid carbon dioxide storage container 2 stored inside the protective container 4. The outline of the storage container 2 is the same as that of the previous embodiment. The protective container 4 has an internal / external pressure adjusting mechanism 44 on the body body 41 having an internal volume sufficient to store the storage container 2, the open / close door 42, and preferably on the opposite surface (upper surface in the drawing) of the open / close door 42. And. The main body 41 is provided with heat insulation and / or pressure resistance, and the open / close door 42 has similar properties. In the present embodiment, the protective container 4 itself plays the role of the weight 32 in the previous embodiment. Therefore, the protective container 4 has a certain weight or, if necessary, a weight portion is separately provided on the main body 41 or the open / close door 42. It may be done.

  As shown in the circle of FIG. 5, the internal / external pressure adjusting mechanism 44 has a valve 44a that opens when the internal pressure of the protective container 4 increases to a predetermined pressure or higher, and conversely, the external pressure (water pressure) of the protective container 4 is a predetermined pressure. It consists of a valve 44b that opens when it rises above. The valve 44a is opened before reaching the pressure limit pressure of the protective container 4, the valve 44b is opened before the pressure difference between the inside and outside of the protective container 4 reaches the pressure limit of the protective container 4, and the outside of the protective container 4 is brought to the critical water pressure. After reaching, it is configured to be opened. The illustration is merely an example, and other structures may be used. Further, in the illustrated example, the valves 44 a and 44 b are provided coaxially, but those having the same function may be provided in different parts of the main body 41.

  The liquid carbon dioxide deep sea settlement system according to the present embodiment operates as follows. 3 to 5, liquid carbon dioxide is injected into the storage container 2 until the lid 24 is closed, which is the same as in the previous embodiment. The storage container 2 into which liquid carbon dioxide has been injected is then stored in the protective container 4 and the open / close door 42 is closed. Then, the protective container 4 is attached to the subsidence guide mechanism 3, suspended by the crane 11 of the offshore facility 1 and submerged in the sea.

  Meanwhile, the liquid carbon dioxide inside the storage container 2 starts to vaporize due to the environmental temperature and pressure, and the pressure of the storage container 2 increases to reach the first limit pressure set corresponding to the pressure limit of the storage container 2. Then, the gas venting mechanism 23 (see FIG. 2) of the lid 24 operates to release the carbon dioxide gas inside. However, the escaped gas stays in the sealed protective container 4, so that the pressure in the protective container 4 is increased. When the pressure in the protective container 4 and the pressure in the storage container 2 are in an equilibrium state, the valve of the degassing mechanism 23 is closed and further release of vaporized carbon dioxide is prevented. At this time, since the pressure inside and outside the storage container 2 is in an equilibrium state, the storage container 2 does not burst. Then, after the pressure is gradually increased by vaporization of liquid carbon dioxide and the equilibrium state is maintained for a while, when the internal pressure in the protective container 4 reaches the second limit pressure set corresponding to the pressure limit of the protective container 4 The valve 44a of the internal / external pressure adjusting mechanism 44 is opened, and carbon dioxide filled in the protective container 4 is released into the seawater.

  After that, when the protective container 4 sinks and reaches a predetermined depth, the external water pressure is increased more than the internal pressure of the protective container 4 and the internal and external values set in advance corresponding to the pressure limit of the protective container 4 are increased. The third limit pressure of the pressure adjusting mechanism 44 is reached, thereby opening the valve 44b and allowing seawater to enter the protective container 4. Pressure is applied to the protective container 4 by seawater intrusion, and the vaporization of liquid carbon dioxide in the liquid carbon dioxide storage container 2 is suppressed. Eventually, the critical water pressure sufficient to prevent the vaporization is reached, the vaporization is stopped, the valve 44b is opened, and the pressure inside and outside the storage container 2 (and the pressure inside and outside the protective container 4) is in an equilibrium state. Therefore, liquid carbon dioxide is enclosed in the storage container 2. In this state, the open / close door 42 can be opened, and the storage container 2 is discharged from the protective container 4 and naturally settles down to the sea floor and lands. The protective container 4 is recovered by pulling up the guide wire 31 and can be reused. The anchor wire 5 that has finished its role is also collected. In addition, the anchor wire 5 is not limited to this Embodiment, It can use similarly similarly in other Embodiment as needed.

  As described above, the main body 41 of the protective container 4 is provided with heat insulation and / or pressure resistance. By surrounding the liquid carbon dioxide storage container 2 with the heat-insulating protective container 4, the storage container 2 storing the low-temperature liquid carbon dioxide does not touch the outside air and seawater directly, preventing rapid temperature rise and liquid carbon dioxide. The amount of vaporization can be reduced, and the storage efficiency can be increased. Further, if the main body 41 has pressure resistance, the carbon dioxide released from the storage container 2 can be confined in the protective container 4 to pressurize the storage container 2 by the action of the carbon dioxide itself, Increase storage efficiency by reducing the amount of carbon dioxide produced. If the protective container 4 is provided with both heat insulation and pressure resistance, the effect of further increasing the storage efficiency can be obtained by a synergistic effect. In other words, the protective container 4 according to the present embodiment provides one or both of heat insulation and pressure resistance with respect to the previous embodiment to increase the storage efficiency of carbon dioxide, that is, reduce the amount of carbon dioxide that escapes. It has the effect to make it. Even if the degree of heat insulation and pressure resistance is small, it has a function of increasing the recovery efficiency compared to the previous embodiment, and the higher the degree of heat insulation and pressure resistance, the higher the efficiency. . As the heat insulating material, use can be made of expanded polystyrene used in a refrigerator or the like, and a continuous urethane vacuum heat insulating material having a higher heat insulating property.

  FIG. 6 shows another aspect of the liquid carbon dioxide deep sea settlement system according to the present embodiment. Here, the liquid carbon dioxide storage container 2 is housed in the protective container 4a in an almost intimate relationship, and the protective container 4a does not have the internal / external pressure adjustment mechanism 44 (see FIG. 5), but has only the opening 43. is doing. In the illustrated example, the lid 24 of the storage container 2 is seen through the opening 43. The main body 41a of the protective container 4a has heat insulation and / or pressure resistance, or both, and the opening / closing door 42a is the same as the previous embodiment.

  When the protective container 4a shown in FIG. 6 is used, the protective effect can be further enhanced because the protective container 4a is in close contact with the liquid carbon dioxide storage container 2. In particular, when the protective container 4a has pressure resistance (even if it has a heat insulating property, it can generally provide a certain level of pressure resistance depending on its strength), the pressure in the storage container 2 is reduced by the vaporization of carbon dioxide. Even if the height is increased, the protective container 4a restrains the deformation from the outside and further prevents rupture, so that the storage container 2 can withstand an internal pressure up to a higher limit pressure provided in the protective container 4a. . Accordingly, the limit pressure at which the valve of the degassing mechanism 23 (see FIG. 22) of the lid 24 opens can be increased from the limit pressure of the storage container 2 to near the limit pressure of the protective container 4a, and carbon dioxide is released accordingly. The amount can be reduced. When the limit pressure of the protective container 4 a is exceeded, the carbon dioxide gas inside the storage container 2 is released to the outside through the gas venting mechanism 23. Even when the protective container 4a having heat insulation properties is used, the amount of carbon dioxide released can be similarly reduced due to the temperature-insulating effect.

  When the storage container 2 including the protective container 4a sinks to a predetermined depth, seawater enters the protective container 4a from the opening 43 of the protective container 4a by water pressure, and directly applies pressure to the storage container 2. Then, when reaching the deep sea of about 500 m, a gap is formed between the storage container 2 and the protective container 4a, which are compressed by the amount of carbon dioxide gas escaped and deformed into a concave shape. At this stage, the opening / closing door 42a is opened. The storage container 2 can be separated and released from the protective container 4a. After that, only the storage container 2 naturally sinks to the seabed, and the protective container 4a can be recovered in the same manner as in the previous embodiment.

  Next, a liquid carbon dioxide storage container subsidence system according to a third embodiment of the present invention will be described with reference to the drawings. In the present embodiment, only the storage container is submerged on the seabed. In the embodiments so far, the storage container 2 is sunk to a predetermined depth as fast as possible using the sinking guide mechanism 3 (see FIG. 1), the protective container 4 (see FIG. 4), etc. It is assumed that the container 2 is sunk by its own weight. When only the storage container 2 is sunk, the container is ruptured by rapidly passing near the sea surface where the temperature is relatively high and the pressure is low in order to minimize vaporization of liquid carbon dioxide and crashing into the seabed at high speed. The conflicting problem of avoiding fear must be resolved. According to the use of the subsidence guide mechanism 3 and the protective container 4 used in the first and second embodiments, the submersion guide mechanism 3 and the protective container 4 are submerged at a sufficient depth to prevent carbon dioxide vaporization. The problem was solved by releasing and letting it fall naturally.

  In the storage container 2a according to the present embodiment shown in FIG. 7A, a weight portion 25a having a sufficient weight so as to be able to sink at high speed near the sea surface is provided in the lower part of the figure. Although the overall shape is arbitrary, in the illustrated example, a teardrop shape is used so as to reduce the resistance during sinking as much as possible. The main body 21a has a substantially frustoconical shape, and an opening is provided on the upper side so that a lid 24 provided with a gas venting mechanism 23 can be attached. By adopting such a shape, the vaporized carbon dioxide tends to gather at the upper end of the truncated cone, and the sinking posture of the storage container 2a is easily determined by the weight 25a on the lower side and the gas on the upper side. It is preferable from the viewpoint of storage efficiency that what escapes to the outside due to the increase in internal pressure of the storage container 2a is vaporized carbon dioxide instead of liquid carbon dioxide. By arranging the weight 25a and the lid 24 on the opposite sides in this way, the gas portion, that is, the portion with a low specific gravity, gathers upward, so that only the carbon dioxide vaporized can escape.

  Around the outside of the main body 21a, a plurality of resistance umbrellas 26, which are fixed so as to be pivotable upward with a support shaft, are arranged extending downward along the main body 21a. The lower end of the resistance umbrella 26 is restrained from the periphery by a holding wire 27, and the holding wire 27 is connected by a pressure-sensitive lock 28. The operating pressure that triggers the operation of the lock 28 is preferably adjustable.

  The operation of the liquid carbon dioxide storage container 2a according to the present embodiment configured as described above is the same as that of the other embodiments until the liquid carbon dioxide is injected into the container. After the injection, a guide such as the subsidence guide mechanism 3 is not required, and it is only necessary to drop it into the sea in the designated sea area. The dropped storage container 2a has carbon dioxide vaporized in the storage container 2a in the sea by the action of the heavy weight part 25a with the shape with less resistance with the heavy weight part 25a facing downward and the light lid 24 facing upward. It sinks rapidly into the sea while being released. When the critical water pressure for preventing vaporization is reached, the vaporization stops, and the remaining liquid carbon dioxide is sealed in the storage container 2a in a liquid state.

  Since the lock 28 is operated by water pressure to reach a critical depth (about 500 m) or deeper than a predetermined depth and the holding wire 26 is released, the resistance umbrella 26 is opened by the water pressure at the time of subsidence, and the broken line Opened in a parasol shape as shown in. As a result, the subsidence speed is drastically reduced, and after that, the subsidence is settled down to the seabed at a predetermined speed to enable safe landing. The resistance umbrella 26 is opened in a comb-like shape in the illustrated example, but a film may be stretched between the umbrellas if necessary. Or it is not limited to such an umbrella-shaped thing, For example, the deceleration means known by the prior art, such as a parachute-shaped thing opening, may be utilized.

  By configuring the liquid carbon dioxide storage container 2a as described above, operations necessary when the subsidence guide mechanism 3 is used are not required, and the storage container 2a is simply dropped into the sea. This greatly simplifies the process. Further, without being bothered by the sinking process of the storage container 2a that has previously been sunk, the recovery of the protective container 4, etc., it is possible to dump one after another, and work efficiency can be improved.

  The liquid carbon dioxide storage container 2b shown in FIG. 7B realizes the same idea with a simpler structure, and at least a part of the weight portion 23b provided in the lower portion of the main body 21b can be separated. It is configured. When the storage container 2b reaches the deep sea of the critical depth, the lock that operates in response to the pressure (not shown) is released, and at least a part of the weight part 25b is separated as indicated by a broken line, and only the part is first. Sink. The storage container 2b, which has become lighter as a result of part of the weight portion 25b separating, has its sinking speed reduced, and can softly land on the seabed. The ratio of the part to be separated and the weight portion 25b remaining on the main body 21b side can be appropriately selected according to the specifications of the storage container 2b.

  Note that the liquid carbon dioxide storage containers 2a and 2b shown in the present embodiment are both in direct contact with the outside air and seawater, but are protective containers having heat insulation and pressure resistance as shown in the second embodiment. You may make it cover. However, in this case, the protective container is separated when it reaches a predetermined depth, and usually cannot be recovered because it is left in the sea. However, it can be recovered by setting the protective container to a specific gravity of 1 or less. In particular, in the case of the storage container 2b shown in FIG. 7B, the storage container 2b may be kept covered even when reaching the seabed without separating the protective container. However, the heat insulation and pressure resistance of the protective container are not required on the seabed.

  When the liquid carbon dioxide storage containers 2a and 2b shown in the present embodiment are used, since there is no guide after dropping into the sea, it is difficult to determine the subsidence direction until reaching the seabed. Therefore, it can be said that the system described in this embodiment is suitable for use in a sea area where the flow is gentle. However, if the anchor wire 5 as shown in FIG. 4 is used, the problem is solved, and centralized storage in a predetermined sea area is also possible.

  As described above, the embodiments of the present invention have been described mainly with respect to the liquid carbon dioxide deep sea subsidence system. However, as described in the beginning and each embodiment, the present invention should be implemented using these systems. It also includes liquid carbon dioxide deep sea subsidence methods. According to the subsidence method, carbon dioxide that raises the internal pressure of the storage container by vaporizing liquid carbon dioxide is safely subsidized while being released to the outside. A high pressure vessel is not required (or, in fact, difficult to implement with the prior art), and it is a flexible material that can be deformed according to the pressure received at the seabed, but it bursts during subsidence. Therefore, it is possible to select a material for a storage container that does not corrode even when exposed to seawater for many years. And the loss by discharge | release of the vaporized carbon dioxide can also be reduced as much as possible by adding the method of protecting the said storage container from the outside with the protective container which has heat insulation and pressure | voltage resistance.

  In addition, the present invention also includes a method for preserving liquid carbon dioxide under the sea, which is made possible by using the liquid carbon dioxide deep sea settlement method as described above.

  Prevention of global warming is a global mission, and the present invention can be widely used in the industrial field for maintaining the global environment by preserving liquid (solid) carbon dioxide at the sea bottom.

  1. 10. offshore facilities; Crane, 2. 20. Liquid carbon dioxide storage container (storage container) Body body, 22. Inlet, 23. Degassing mechanism 24. Lid, 25. Subsidence weight, 26. Resistance umbrella, 27. Retaining wire, 28. 2. lock, Subsidence guide mechanism, 31. Guide wire, 32. Weight, 33. Motor, 4. Protective container, 41. Body body, 42. Open / close door, 43. Opening, 44. 4. Internal / external pressure adjustment mechanism, Anchor wire, 51. anchor.

JP-A-3-69508

Claims (11)

The storage container containing liquid carbon dioxide sinks without being ruptured by the internal pressure of the vaporized liquid carbon dioxide until reaching the deep sea where the water pressure is sufficient to prevent vaporization of the stored liquid carbon dioxide. A liquid carbon dioxide deep sea subsidence method,
Before reaching the critical depth, at least part of the vaporized carbon dioxide is removed from the storage container before the internal pressure of the storage container, which is increased by the vaporized carbon dioxide, reaches a limit pressure for rupturing the storage container. A method of sinking the storage container while discharging.   2. The method according to claim 1, wherein the storage container is covered with a protective container provided with one or both of heat insulation and pressure resistance at least until the critical depth is reached. 2. The method according to claim 1, wherein the storage container is subsidized at a depth exceeding the critical depth at a subsidence rate lower than the subsidence rate until reaching the critical depth. And sinking speed between the up to the critical depth, the speed difference between the sink rate at a depth exceeding the critical depth, the action of the weight is between up to a critical depth, or the housing Attach the container to drive the guide wire that leads to the deep sea and settling by using any of the driving force that forcibly pulls the storage container into the deep sea, and at a depth exceeding the critical depth , the weight weight is reduced , wherein the free fall or by Ri obtained Rukoto to the subsidence using any of deceleration umbrella of the accommodating unit, in the sea of the receiving container, the method according to claim 3.   5. The method of claim 1, wherein the carbon dioxide in the atmosphere is separated into liquid carbon dioxide, and the liquid carbon dioxide is stored in a storage container and submerged and stored on the sea floor. A method for storing liquid carbon dioxide in the seabed, comprising sinking the storage container to the seabed by the method described in 1. The storage container containing liquid carbon dioxide sinks without being ruptured by the internal pressure of the vaporized liquid carbon dioxide until reaching the deep sea where the water pressure is sufficient to prevent vaporization of the stored liquid carbon dioxide. A deep carbon subsidence system for liquid carbon dioxide that softly lands on the seabed at a speed that does not cause the storage container to rupture,
Transporting the liquid carbon dioxide produced in the ground, or a marine facility having a facility for producing a liquid body of carbon dioxide,
A storage container for storing liquid carbon dioxide;
A subsidence guide mechanism that sinks the storage container to at least the critical depth;
The storage container includes a degassing mechanism that releases at least a part of the vaporized carbon dioxide to the outside before the internal pressure due to the vaporization of liquid carbon dioxide reaches a limit pressure that bursts the storage container. With flexibility that can be deformed according to the water pressure received in the deep sea by weight loss due to gas release, and corrosion resistance to seawater,
The deep sea settlement system, wherein the settlement guide mechanism includes a weight or a driving device for drawing the storage container into the sea. Wherein the subsidence guide mechanism, covering the container, thermal insulation, with one or both of the pressure resistance, and protective container is further attached to release the container reached the critical depth The deep sea settlement system according to claim 6. An internal / external pressure adjusting mechanism that releases internal gas when the internal pressure of the protective container reaches a predetermined value, and introduces external seawater when the water pressure outside the container reaches a predetermined value. The deep sea subsidence system according to claim 7 , comprising: It contains liquid carbon dioxide and sinks into the sea without rupturing at the internal pressure of the vaporized liquid carbon dioxide until it reaches the deep sea where the water pressure is sufficient to prevent vaporization of the stored liquid carbon dioxide. A liquid carbon dioxide storage container that softly lands on the seabed at a speed that does not burst further,
The storage container includes a degassing mechanism that discharges at least a part of the vaporized carbon dioxide to the outside before the internal pressure due to the vaporization of liquid carbon dioxide reaches a limit pressure that bursts the storage container.
A liquid carbon dioxide storage container characterized by having flexibility that can be deformed according to water pressure received in the deep sea by weight loss due to gas release, and corrosion resistance to seawater.   The liquid carbon dioxide storage container according to claim 9, further comprising a speed reduction mechanism that reduces a settlement speed after exceeding the critical depth.   11. The liquid carbon dioxide storage container according to claim 10, wherein the speed reduction mechanism is one of a resistance umbrella opening / closing mechanism and a weight separating mechanism.

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