Carbon dioxide production method and carbon dioxide production apparatus used in same

Abstract

The present invention provides a carbon dioxide production apparatus that makes it possible to easily reduce greenhouse gas such as carbon dioxide, provide carbon dioxide at a low price, and conserve the marine environment, and a carbon dioxide production method. A carbon dioxide production apparatus 1 for producing carbon dioxide from calcium carbonate comprises: a calcination furnace 2 which is configured such that a lid can hermetically seal a calcium carbonate charging port of the furnace body; and a surge tank 3 which is connected to the calcination furnace 2. The calcination furnace 2 is configured to be capable of hermetically sealing a prescribed amount of calcium carbonate, and is designed to be heated to a temperature at which the prescribed amount of calcium carbonate in the calcination furnace 2 is decomposed into calcium oxide and carbon dioxide. The surge tank 3 is formed in the size that enables the recovery of an amount of generated carbon dioxide which is calculated on the basis of the prescribed amount of calcium carbonate charged into the calcination furnace 2, so that carbon dioxide obtained when the calcium carbonate in the calcination furnace 2 is heated to decompose into calcium oxide and the carbon dioxide is recovered.

Description

Carbon dioxide production method and carbon dioxide production device used therefor

[0001] The present invention relates to a carbon dioxide production method and a carbon dioxide production apparatus used therein.

[0002] Currently, in order to prevent global warming, efforts are being made worldwide to reduce carbon dioxide emissions into the atmosphere and to capture carbon dioxide that has already been emitted into the atmosphere.

[0003] One of the techniques proposed to reduce the concentration of carbon dioxide in the atmosphere is to capture carbon dioxide from the exhaust gas outlets of factories and other facilities, and then mineralize and fix the captured carbon dioxide underground. A storage facility for this technology has already been demonstrated (see, for example, Non-Patent Document 1).

[0004] Another proposed technology involves recovering carbon dioxide from the atmosphere, dissolving the recovered carbon dioxide in water, injecting it into the ground, allowing it to be absorbed and fixed in the ground, and then recovering the hot spring water (see, for example, Patent Document 1).

[0005] IPCC (2005) Special Report on Carb on Dioxide Capture and Storage: Prepared by Working Group III of the International Panel on Climate Change. Cambridge University Press, Cambridge and New York, 422 pp. Special table 2017-528318 publication

[0006] However, recovering carbon dioxide from the exhaust gas outlet only reduces the amount of carbon dioxide emitted into the atmosphere, and does not recover carbon dioxide that has already been released and dispersed into the atmosphere.

[0007] Furthermore, whether capturing carbon dioxide from exhaust gas outlets or from the atmosphere, it is mineralized and fixed underground, and in both cases, it is thought that the calcium oxide contained in the basalt that makes up the Earth's crust reacts with carbon dioxide to form calcium carbonate, which is fixed underground. However, if carbon dioxide is directly transported from the atmosphere into the ground and mineralized and fixed in this way, it may be possible to achieve the goal when considering only the reduction and capture of carbon dioxide, but because it is far removed from the mechanisms for carbon dioxide reduction and capture that are originally performed by the natural environment, it will give rise to other issues, and there is a concern that it will take time to improve the marine environment, which has been deteriorated by the increase in atmospheric carbon dioxide.

[0008] Furthermore, in order to reduce the concentration of carbon dioxide in the atmosphere, efforts are being made to switch from fossil fuels to renewable energy sources such as solar energy, and there is a movement to abolish fossil fuel refining facilities. As a result, there is a shortage of industrial carbon dioxide gas, which was produced as a by-product during refining at these fossil fuel refining facilities, and the price of industrial carbon dioxide gas has risen sharply, leading to a shortage of drinking water such as carbonated water. For this reason, the technology described in Patent Document 2 is used to recover carbon dioxide from the atmosphere and dissolve the recovered carbon dioxide in water to produce carbonated drinking water. However, when recovering carbon dioxide from the atmosphere, an absorption medium is required to absorb the carbon dioxide, and after the carbon dioxide has been absorbed by this absorption medium, the carbon dioxide must be extracted from the absorption medium and dissolved in water to produce carbonated water, which increases costs.

[0009] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a carbon dioxide production device and a method for producing the same that can easily reduce greenhouse gases such as carbon dioxide, provide carbon dioxide at low cost, and improve the marine environment.

[0010] The carbon dioxide production apparatus of the present invention for solving the above-mentioned problems is an apparatus for producing carbon dioxide from calcium carbonate, and includes a calcination furnace configured so that a lid can seal a calcium carbonate inlet of a furnace body, and a surge tank connected to the calcination furnace, the calcination furnace being configured so that a predetermined amount of calcium carbonate can be sealed and is configured to heat the predetermined amount of calcium carbonate in the calcination furnace up to a temperature at which the calcium carbonate decomposes into calcium oxide and carbon dioxide, and the surge tank is sized to be able to recover the amount of carbon dioxide generated calculated from the predetermined amount of calcium carbonate charged into the calcination furnace, so as to recover the carbon dioxide obtained when the calcium carbonate in the calcination furnace is heated and decomposed into calcium oxide and carbon dioxide.

[0011] In the carbon dioxide production apparatus, the calciner may be configured to be heated by a normal power source or waste heat from an incinerator or the like.

[0012] In the carbon dioxide production apparatus, the calciner may be configured to be heated using renewable energy.

[0013] In the carbon dioxide generating apparatus, the surge tank may be formed of a sheet-like bag whose capacity is adjustable.

[0014] In the carbon dioxide production device, the bag body is attached to a pair of frames, and the frames are controllable from a close state to a separated state and from the separated state to a close state, and when the frames are controlled from the close state to the separated state, the capacity of the bag body is increased, and when the frames are controlled from the separated state to the close state, the capacity of the bag body is decreased.

[0015] In the carbon dioxide production device, the bag may be stored in a rigid container large enough to store the bag, and the inside of the container may be depressurized or pressurized by a pump, so that the volume of the bag increases when the inside of the container is depressurized, and decreases when the inside of the container is pressurized.

[0016] The carbon dioxide production apparatus may be one in which a cooling passage is provided between the calcination furnace and the surge tank.

[0017] In order to solve the above-mentioned problems, the method for producing carbon dioxide of the present invention comprises sealing a predetermined amount of calcium carbonate in a calcination furnace configured to be airtight, heating the calcium carbonate in the calcination furnace to decompose it into calcium oxide and carbon dioxide, and recovering the resulting carbon dioxide in a surge tank having a size capable of recovering the amount of carbon dioxide generated calculated from the predetermined amount of calcium carbonate.

[0018] The method for producing carbon dioxide may use seashells as calcium carbonate.

[0019] In the method for producing carbon dioxide, the shells may be those that have been irradiated with ultraviolet light or dried in the sun.

[0020] In the method for producing carbon dioxide, the calcium carbonate may be calcium oxide obtained by exposing the calcium oxide obtained by the method for producing carbon dioxide to the atmosphere, causing the calcium oxide to absorb carbon dioxide in the atmosphere and return to calcium carbonate.

[0021] The method for producing carbon dioxide may also be a method for producing lime water from the obtained calcium oxide and supplying the lime water to the sea.

[0022] The method for producing carbon dioxide may involve scattering the obtained calcium oxide on a sandy beach on the land side of the high tide shoreline.

[0023] The carbonated water of the present invention, which solves the above-mentioned problems, is obtained by dissolving carbon dioxide obtained by the above-mentioned carbon dioxide production method in water.

[0024] As described above, according to the present invention, the lid is configured to seal the calcium carbonate inlet of the furnace body. Therefore, when the calcination furnace containing calcium carbonate is heated, carbon dioxide generated from the calcium carbonate is collected in a surge tank connected to the calcination furnace. The surge tank is sized to collect the amount of carbon dioxide calculated from the amount of calcium carbonate introduced into the calcination furnace, so that the carbon dioxide generated when calcium carbonate is heated in the calcination furnace and decomposed into calcium oxide and carbon dioxide can be collected. Furthermore, heating calcium carbonate in this manner produces calcium oxide along with carbon dioxide. However, if the calcium oxide is left in the atmosphere, it absorbs carbon dioxide and returns to calcium carbonate. This process allows the carbon dioxide from the atmosphere to be captured. Furthermore, the converted calcium carbonate can be reused to produce carbon dioxide, allowing carbon dioxide to be produced while capturing carbon dioxide from the atmosphere.

[0025] Fig. 1 is a schematic diagram showing an outline of the overall configuration of a carbon dioxide production apparatus according to the present invention. (a) and (b) are horizontal and vertical cross-sectional views showing a calcination furnace of a carbon dioxide production apparatus according to the present invention. (a) and (b) are cross-sectional views showing an example of a surge tank of a carbon dioxide production apparatus according to the present invention before and after filling. (a) and (b) are cross-sectional views showing another example of a surge tank of a carbon dioxide production apparatus according to the present invention before and after filling. Detailed Description of the Invention

[0026] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0027] Fig. 1 shows an outline of the overall configuration of a carbon dioxide production apparatus 1 according to the present invention, Fig. 2 shows a calcination furnace 2 of the carbon dioxide production apparatus 1, and Figs. 3 and 4 show a surge tank 3 of the carbon dioxide production apparatus 1. That is, the carbon dioxide production apparatus 1 is equipped with a calcination furnace 2 and a surge tank 3, and is used to produce calcium carbonate (CaCO ３ from carbon dioxide CO ２ It is possible to manufacture the following.

[0028] As shown in Figure 2, the kiln 2 has a furnace body 21 having a generally U-shaped horizontal and vertical cross section, with one side serving as an inlet 21a, and a lid 22 that fits over the inlet 21a, so that the lid 22 can seal the inlet 21a of the furnace body 21. The lid 22 consists of a lid portion 22a that fits over the inlet 21a of the furnace body 21 and a cart-shaped container portion 22b into which calcium carbonate can be added. When the container portion 22b is slid into the furnace body 21, the lid portion 22a of the lid 22 can seal the inlet 21a of the furnace body 21. This sealing is achieved by operating a handle 23 to close the lid portion 22a of the lid 22 via a hinge 24, and then closing a sealing fitting 25 between the inlet 21a of the furnace body 21 and the lid portion 22a of the lid 22, thereby maintaining the interior of the kiln 2 sealed. The capacity of the calcination furnace 2 is set so that it can store a predetermined amount of calcium carbonate. This predetermined amount of calcium carbonate is not particularly limited and may be, for example, 50 kg, 100 kg, or 1 ton. However, since an increase in the processing amount will increase the amount of carbon dioxide generated, an amount of about 100 kg is preferable.

[0029] The firing furnace 2 is capable of heating the sealed space to approximately 850°C in a sealed state by a heating element 26 in the furnace body 21 provided in the sealed space. The interior of the sealed space is constructed of a ceramic insulation material C, and the exterior is constructed of a rigid case F with an air insulation layer A interposed therebetween. The furnace body 21 of the firing furnace 2 is provided with an exhaust path 27 that runs from the insulation material C through the air insulation layer A to the rigid case F. The heating element 26 is not limited to any particular type as long as it can heat the interior of the firing furnace 2 to 850°C, and heating elements 26 used for resistance heating, arc heating, induction heating, dielectric heating, infrared heating, microwave heating, arc plasma heating, etc. can be used. Furthermore, although the firing furnace 2 has a side opening structure, it is not particularly limited to this type and may also be a top opening type. Various configurations can be used as long as the interior of the furnace body 21 can be kept sealed.

[0030] The surge tank 3 is connected to an exhaust path 27 provided in the incinerator 2, thereby connecting to the sealed interior of the incinerator 2. The surge tank 3 is sized to recover the amount of carbon dioxide calculated from a given amount of calcium carbonate stored in the incinerator 2 when the given amount of calcium carbonate decomposes into calcium oxide and carbon dioxide. For example, approximately 100 g of calcium carbonate decomposes into approximately 56 g of calcium oxide and approximately 44 g of carbon dioxide. Since approximately 44 g of carbon dioxide is equivalent to approximately 22.4 liters per mole, if the incinerator 2 can store 100 kg of calcium carbonate, the surge tank 3 must be sized to recover 22.4 liters x 1,000, or 22,400 liters of carbon dioxide. However, since moisture and other substances in the air will be gasified and contained in the surge tank, a sufficient capacity is set, for example, to 25,000 liters or 30,000 liters. However, the size of the surge tank 3 is merely an example, and is calculated from a predetermined amount of calcium carbonate to be used depending on the size of the calcination furnace 2. The surge tank 3 may be configured as a sheet-like bag 30 for capturing gas.

[0031] For example, as shown in FIG. 3 , the bag 30 is formed in the shape of a cube or a rectangular parallelepiped, and its bottom surface 30 a is fixed to a base portion 31 a of a frame 31 that is framed so as to surround the bag 30, and its top surface 30 b is fixed to a lattice-shaped frame 32 that matches the top surface 30 b. The frame 32 is configured to be suspended by a wire 35 from a motor 33 provided on the side of the base portion 31 a of the frame 31 via a pulley 34 attached to the top of the frame 31, and by winding the wire 35 by driving the motor 32, The frame 32 can be raised relative to the base 31a of the frame 31, and when winding by the motor 33 is stopped and the torque is released, the frame 32 and the bag 30 can descend under their own weight. By controlling the drive by the motor 33 in this way, the frame 32 can be raised and lowered relative to the base 31a of the frame 31, and accordingly, the bottom surface 30a of the bag 30 fixed to the base 31a of the frame 31 and the top surface 30b of the bag 30 fixed to the frame frame 32 can be brought into a close and separated state. In addition, the space between the bottom surface 30a and the top surface 30b of the bag 30 is formed in a bellows shape at a constant interval in the height direction, and when the close state is reached, the capacity of the bag 30 decreases, and when the separated state is reached, the capacity of the bag 30 increases. Therefore, in cases where a large amount of carbon dioxide is generated in the firing furnace 2 and it is desired to quickly exhaust the carbon dioxide from the exhaust path 27 to the bag body 30, or in cases where the carbon dioxide generated in the firing furnace 2 cannot be exhausted unless it is guided from the exhaust path 27 to the bag body 30, by controlling the frame frame 32 to be spaced apart from the base frame 31 and increasing the capacity of the bag body 30, the inside of the bag body 30 becomes negative pressure, and the carbon dioxide generated in the firing furnace 2 can be guided to the bag body 30 and collected. The location of the gas inlet / outlet 30c for storing or venting carbon dioxide inside the bag body 30 is not particularly limited as long as it is located in a position that allows carbon dioxide to smoothly enter and exit through the inlet / outlet 30c without interfering with the increase or decrease in the capacity of the bag body 30. The inlet / outlet 30c can be located near the periphery of the bottom surface 30a, on the top surface 30b, or on a side surface. It is most preferable to provide it in the center of the bottom surface 30a.

[0032] 4, the bag 30 may be formed in a spherical shape and stored in a rigid container 36 configured to accommodate the bag 30. This storage is performed by inserting the bag 30 through an opening 36a provided in the bottom of the rigid container 36. A gas inlet / outlet 30c of the bag 30 is also aligned with the opening 36a, and with the bag 30 stored in the rigid container 36, the opening 36a of the rigid container 36 is closed by the inlet / outlet 30c of the bag 30, forming a closed space s between the bag 30 and the storage container 36. A supply / exhaust pipe 36b is provided at the top of the rigid container 36 and communicates with the closed space s. With this configuration, for example, when the closed space s is depressurized using the pump 37 through the supply and exhaust pipe 36b, the bag 30 expands within the rigid container 36, increasing the volume of the bag 30, and when the closed space s is pressurized, the volume of the bag 30 within the rigid container 36 decreases. Therefore, in cases where a large amount of carbon dioxide is generated in the firing furnace 2 and it is desired to quickly exhaust it from the exhaust path 27 to the bag 30, or in cases where carbon dioxide generated in the firing furnace 2 cannot be exhausted unless it is guided from the exhaust path 27 to the bag 30, the pump 37 can be driven to expand the bag 30 within the rigid container 36, thereby increasing the volume of the bag 30, creating a negative pressure inside the bag 30 and allowing the carbon dioxide generated in the firing furnace 2 to be guided into the bag 30 and recovered.

[0033] The inlet / outlet 30c of the bag 30 is connected to an exhaust path 27 of the firing furnace 2. The exhaust path 27 is made of a heat-resistant pipe because high-temperature carbon dioxide generated in the firing furnace 2 passes through it. Furthermore, it is preferable that the exhaust path 27 be made of a metal pipe, such as a copper pipe, which has a high cooling effect, so that the carbon dioxide generated in the firing furnace 2 is cooled when it is collected in the surge tank 3. In this case, the exhaust path 27 may be cooled by heat exchange, such as air cooling or water cooling. Furthermore, if the exhaust path 27 is configured to follow changes in the capacity of the bag 30 in the surge tank 3, the inlet / outlet 30c of the bag 30 may be extended in a tubular form near the connection point with the bag 30 to connect to the metal pipe exhaust path 27. Alternatively, the metal pipe exhaust path 27 may be extended to a heat-resistant and flexible silicone tube or the like, and connected to the inlet / outlet 30c of the bag 30 via the silicone tube or the like exhaust path 27.

[0034] Next, a description will be given of a method for producing carbon dioxide using the carbon dioxide production apparatus 1 configured as described above. The following operations are controlled by a control unit 4 connected to the calciner 2 and surge tank 3.

[0035] First, calcium carbonate is charged into the container portion 22b of the lid 22 of the firing furnace 2, the charging port 21a of the furnace body 21 and the lid 22 are closed, and the sealing fitting 25 is closed to seal the calcium carbonate inside the firing furnace 2.

[0036] At this time, the surge tank 3 is left in a state where the bag body 30 is reduced to the minimum and nothing is contained therein.

[0037] Next, heating by the heating element 26 of the calcination furnace 2 begins, and the temperature rises to approximately 850°C, decomposing the calcium carbonate into calcium oxide and carbon dioxide. As the temperature of the calcination furnace 2 rises and carbon dioxide begins to be generated within the calcination furnace 2, the pressure within the calcination furnace 2 rises, but there is a pressure loss when passing through the exhaust path 27, and there is a concern that the gas may not flow smoothly to the surge tank 3. At this time, as explained above, the surge tank 3 is controlled to generate a negative pressure inside the bag 30 to increase its capacity. As a result, the carbon dioxide generated in the calcination furnace 2 is collected within the bag 30 of the surge tank 3.

[0038] The calcium carbonate to be calcined may be limestone or shells. In either case, if the calcium carbonate contains moisture, the surge tank 3 will require additional capacity due to the water vapor, so it must be thoroughly dried before use. Alternatively, a second exhaust path 29 may be provided in the calcination furnace 2, and this second exhaust path 29 may be left open to allow the water vapor to escape until the temperature exceeds 100°C, at which point the water vapor evaporates. When using shells, it is preferable to remove organic components such as proteins from the shells before use. The removal method involves sun-drying the shells with ultraviolet light to decompose and remove the organic components. While acid washing or other methods can be used to remove the organic components, sun-drying in the rain is the most inexpensive and preferable method. If trace amounts of organic components remain, they will be thermally decomposed and carbonized when the temperature rises to approximately 200-300°C. As with the water vapor described above, the second exhaust path 29 may be left open until the decomposition temperature of the organic components is reached, allowing the decomposition gases generated during decomposition to escape. However, even if the decomposition gas of the organic components is exhausted through the second exhaust path 29 and then the second exhaust path 29 is closed, carbonized carbon remains in the calcination furnace 2. In this case, not only carbon dioxide but also carbon monoxide is generated due to the remaining carbon. Therefore, it is preferable to provide a carbon monoxide adsorbent in the exhaust path 27, the inlet / outlet 30c of the bag 30, or inside the bag 30.

[0039] Alternatively, other substances besides carbon dioxide, such as water vapor and carbon monoxide, may be collected in the surge tank 3, and then carbon dioxide may be separated and recovered. In this case, the surge tank 3 is sized to take into account the amount of water vapor and carbon monoxide generated. For example, when crushed limestone or shells are used, the water vapor contained therein is limited to the amount of water vapor generated from moisture equivalent to the saturated water vapor amount at the current temperature. However, when using shells as they are or when using limestone or shells in a coarsely crushed state, the water contained in the form of water of crystallization cannot be removed at 100°C, the boiling point of water, and must be heated to near the decomposition temperature of calcium carbonate. Therefore, when using shells as they are or when using limestone or shells in a coarsely crushed state, it is preferable to collect water vapor along with carbon dioxide and then remove the water vapor later. In this case, the water content of shells or limestone should be considered to be less than 5% of the raw material, and is usually around 2-3%. Strictly speaking, because the molecular weights of water vapor and carbon monoxide are smaller than that of carbon dioxide, the amount of gas generated from the same amount of raw material will be greater for water vapor and carbon monoxide than for carbon dioxide. However, if the surge tank 3 is sized to have a capacity that is at least 10% larger than the amount of carbon dioxide calculated assuming that shells and limestone are 100% calcium carbonate, it will be possible to recover other gases, such as carbon monoxide and water vapor, even if they are generated. Furthermore, carbon monoxide can be converted to carbon dioxide using a catalyst during firing in the firing furnace 2 or when passing through the exhaust path 27, and water vapor can be condensed by cooling in the exhaust path 27, so this can also be addressed. Furthermore, when recovering carbon dioxide from calcium carbonate made from shells or limestone, only carbon dioxide, carbon monoxide, and water vapor are generated, so a bag 30 of the surge tank 3 can be made of a material with a certain degree of flexibility. Therefore, it can withstand an increase in internal pressure in the bag 30 due to the generation of more gas than the specified amount. 1 and 4, a surge tank 3 having a configuration in which a bag 30 is housed in a rigid container 36 can ensure greater safety. Also, the exhaust path 27 or the bag 30 may be provided with a safety valve 28 that opens when the internal pressure rises.

[0040] In this way, carbon dioxide can be collected in the bag 30 of the surge tank 3, and calcium oxide can be obtained in the calcination furnace 2.

[0041] Of these, the carbon dioxide may be used directly from the surge tank 3 or may be refilled into a cylinder for use. For example, when 100 kg of calcium carbonate is processed, 44 kg of carbon dioxide is obtained. When this is used to produce carbonated water, 8,800 bottles of carbonated water can be produced using 5 g of carbon dioxide per 500 ml bottle.

[0042] The carbon dioxide recovered in the surge tank 3 also contains air equivalent to the volume of the calcination furnace 2. Therefore, in order to increase the concentration of carbon dioxide obtained, the calcination furnace 2 may be provided with a decompression pump 20 in the second exhaust path 29 so that the inside of the calcination furnace 2 can be decompressed. In this case, air in the calcination furnace 2 is prevented from being mixed into the surge tank 3, thereby obtaining carbon dioxide of a higher concentration, and the temperature at which calcium carbonate is decomposed can be set lower due to the reduced pressure.

[0043] If calcium oxide is exposed to the atmosphere, it will absorb carbon dioxide again and return to calcium carbonate. Therefore, if this material that has returned to calcium carbonate is used and fired again in the firing furnace 2, carbon dioxide can be produced indefinitely without any material costs. Moreover, since the carbon dioxide obtained in this way is produced by recovering carbon dioxide present in the atmosphere, carbon dioxide recovery can contribute to the prevention of global warming.

[0044] In addition, when calcium carbonate is obtained by exposing calcium oxide to the atmosphere and allowing it to absorb carbon dioxide again, as described above, carbon dioxide can be produced infinitely without any material costs. However, the shells originally used to produce calcium carbonate are generated in large quantities annually as industrial waste, making disposal difficult. Therefore, as described above, shells may continue to be used as a raw material for calcium carbonate. In this case, the resulting calcium oxide must be continuously processed, but the calcium oxide may be used as an industrial material, or may be converted back to calcium carbonate by absorbing carbon dioxide and then used as an industrial material, or may be slaked to form calcium hydroxide and then used as an industrial material.

[0045] Calcium oxide may also be made into limewater and supplied to the ocean. Currently, rising atmospheric carbon dioxide concentrations have led to concerns about global warming. The ocean absorbs the most carbon dioxide on Earth, resulting in ocean acidification, making it difficult for shellfish to grow and causing the disappearance of coral reefs. Continuously supplying limewater to the ocean can act as a buffer against the increased hydrogen ion concentration caused by acidification, preventing further acidification. It can also continuously supply the ocean with calcium ions, essential for the growth of marine exoskeletal organisms such as shellfish and corals. Because limewater can buffer the increased hydrogen ion concentration resulting from the ocean's absorption of two moles of carbon dioxide, it has the same effect as recovering two moles of carbon dioxide.

[0046] In addition to being supplied to the sea as limewater, calcium carbonate can also be spread on sandy beaches landward of the high-tide shoreline or used as plaster. In this case, after absorbing carbon dioxide from the atmosphere and returning to calcium carbonate, the calcium carbonate absorbs more carbon dioxide when struck by rainwater containing carbon dioxide, absorbing two moles of carbon dioxide from the atmosphere and becoming liquid calcium bicarbonate, which then seeps into the ground and flows into the sea, or flows into the sea via rivers and drainage channels. In other words, the calcium carbonate flows into the sea while absorbing two moles of carbon dioxide, becoming bicarbonate ions and calcium ions in the sea, and can continue to supply the sea with calcium necessary for the growth of marine exoskeleton organisms in the form of calcium ions, just as in the case of supplying limewater to the sea as described above.

[0047] In this way, the carbon dioxide generating apparatus 1 of the present invention can produce 1 mole of carbon dioxide from the raw material calcium carbonate and recover 2 moles of carbon dioxide from the resulting calcium oxide. Of this, 1 mole is carbon dioxide that was fixed in the base calcium carbonate, so that essentially 2 moles of carbon dioxide can be recovered.

[0048] However, when using the carbon dioxide production apparatus 1 of the present invention to thermally decompose 100 kg of calcium carbonate to recover 44 kg of carbon dioxide, it is estimated that 17 to 48 g of carbon dioxide is emitted per kWh of solar energy, even when solar energy is used, and 690 g of carbon dioxide is emitted when thermal power generation is used. Therefore, when thermally decomposing 44 kg of carbon dioxide from 100 kg of calcium carbonate, the resulting calcium oxide can recover 2 moles of carbon dioxide, i.e., 44 kg x 2 moles = 88 kg of carbon dioxide. Therefore, if the energy required for thermal decomposition is 5,176 to 1,833 kWh for solar energy or up to 127 kWh for thermal power generation, the carbon dioxide recovery business will be viable. This can be fully achieved even when all of the power required for the carbon dioxide production apparatus 1, including the calcination furnace 2 and surge tank 3 controlled by the control unit 4, is generated solely from thermal power generation. However, when solar power generation is used, the majority of the carbon dioxide can be recovered. When using electricity generated by thermal power generation, the furnace body 21 of the calcination furnace 2 may be attached to a waste heat generating section so that calcium carbonate can be directly thermally decomposed using waste heat without using electricity from a thermal power plant. In addition to thermal power generation, waste heat from municipal waste incinerators or any other place that generates waste heat capable of heating calcium carbonate to 850°C at which calcium carbonate can be thermally decomposed can also be used.

[0049] Furthermore, industrial carbon dioxide has been produced during the refining of oil, and has been produced by emitting carbon dioxide during the refining of oil up until now. Although the base year differs from country to country, Japan aims to reduce greenhouse gas emissions by 46% by 2030 compared to 2013, so in this respect, it is possible to reduce carbon dioxide emissions from manufacturing equipment compared to 2013.

[0050] Furthermore, as the shift from fossil fuels to environmental energy sources such as solar energy is underway, an increasing number of oil refineries are being closed to reduce carbon dioxide emissions, and while the concentration of carbon dioxide in the atmosphere is rising, there is a shortage of carbon dioxide for industrial use. In this case, an alternative technology is needed to produce carbon dioxide for industrial use, and the carbon dioxide production apparatus 1 of the present invention can be used as just such an alternative technology.

[0051] The present invention can be embodied in various other forms without departing from its spirit or main characteristics. Therefore, the above-described examples are merely illustrative in all respects and should not be interpreted as limiting. The scope of the present invention is defined by the claims and is not limited to the text of the specification. Furthermore, all modifications and variations within the scope of the claims are within the scope of the present invention. Industrial Applicability Carbon dioxide reduction can be achieved using existing calcium carbonate raw materials such as seashells, and the absorption of carbon dioxide can also improve the acidifying marine environment.

[0052] REFERENCE SIGNS LIST 1 Carbon dioxide production device 2 Sintering furnace 21 Furnace body 22 Lid 27 Exhaust path 3 Surge tank 30 Bag body 31 Frame 32 Frame frame 36 Rigid container 37 Pump 4 Control unit

Claims

1. An apparatus for producing carbon dioxide from calcium carbonate, comprising: a calcination furnace configured so that a lid can seal a calcium carbonate inlet of the furnace body; and a surge tank connected to the calcination furnace, wherein the calcination furnace is configured so that a predetermined amount of calcium carbonate can be sealed and is adapted to heat the predetermined amount of calcium carbonate in the calcination furnace up to a temperature at which the predetermined amount of calcium carbonate decomposes into calcium oxide and carbon dioxide, and the surge tank is sized to be able to recover the amount of carbon dioxide generated from the predetermined amount of calcium carbonate fed into the calcination furnace, so as to recover the carbon dioxide obtained when the calcium carbonate in the calcination furnace is heated and decomposed into calcium oxide and carbon dioxide.

2. A carbon dioxide production apparatus according to claim 1, wherein the calcination furnace is heated by a normal power source or by waste heat from a heat treatment device which processes at a higher temperature than the calcination furnace.

3. The carbon dioxide production apparatus according to claim 1, wherein the calcination furnace is heated using renewable energy.

4. The carbon dioxide generating device according to claim 1, wherein the surge tank is made of a sheet-like bag whose capacity can be increased or decreased.

5. A carbon dioxide production device as described in claim 4, wherein the bag body is attached to a pair of frames, and the frames are controllable from a close state to a separated state and from a separated state to a close state, and when the frames are controlled from a close state to a separated state, the capacity of the bag body is increased, and when the frames are controlled from a separated state to a close state, the capacity of the bag body is decreased.

6. A carbon dioxide production device as described in claim 4, in which the bag is stored in a rigid container large enough to store the bag, and the pressure inside the container can be reduced or increased by a pump, so that the capacity of the bag increases when the pressure inside the container is reduced, and decreases when the pressure inside the container is increased.

7. The carbon dioxide production apparatus according to claim 1, wherein a cooling passage is provided between the calcination furnace and the surge tank.

8. A method for producing carbon dioxide, comprising sealing a predetermined amount of calcium carbonate in a calcination furnace configured to be airtight, heating the calcium carbonate in the calcination furnace to decompose it into calcium oxide and carbon dioxide, and recovering the resulting carbon dioxide in a surge tank large enough to recover the amount of carbon dioxide generated calculated from the predetermined amount of calcium carbonate.

9. The method for producing carbon dioxide according to claim 8, wherein seashells are used as calcium carbonate.

10. The method for producing carbon dioxide according to claim 9, wherein the shells are irradiated with ultraviolet light or dried in the sun.

11. The method for producing carbon dioxide described in claim 8, wherein calcium carbonate is produced by exposing calcium oxide obtained by the method for producing carbon dioxide described in claim 8 to the atmosphere, causing the calcium oxide to absorb carbon dioxide in the atmosphere and return to calcium carbonate.

12. The method for producing carbon dioxide according to claim 8, wherein lime water is produced from the obtained calcium oxide and supplied to the sea.

13. The method for producing carbon dioxide according to claim 8, wherein the obtained calcium oxide is spread on a sandy beach on the land side of the high tide shoreline.

14. Carbonated water obtained by dissolving carbon dioxide obtained by the method for producing carbon dioxide according to any one of claims 8 to 11 in water.

Images