Carbon dioxide recovery apparatus

Abstract

To provide a carbon dioxide recovery apparatus capable of reducing cost and labor of maintenance and suppressing energy required for recovering carbon dioxide.SOLUTION: A carbon dioxide recovery device 1A causes carbon dioxide to diffuse from absorbing liquid to recover the carbon dioxide by heating the absorbing liquid that has absorbed the carbon dioxide by heating means 7, where the heating means 7 includes a heat exchanger (heat pump) 20 that performs heat exchange between the absorbing liquid and a heating medium, where the absorbing liquid is absorbing liquid that diffuses carbon dioxide at 80 to 100°C, and where the heating medium is a single heating medium having critical temperature equal to or higher than carbon dioxide diffusion temperature+10°C.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a carbon dioxide recovery device that recovers carbon dioxide by dissipating it from an absorbing liquid that has absorbed carbon dioxide by heating the absorbing liquid with a heating means. [Background technology]

[0002] As a method for recovering carbon dioxide, for example, a chemical absorption method that utilizes reactive absorption by an alkaline compound is known. In the chemical absorption method, carbon dioxide contained in a gas is brought into contact with an amine-based absorbing solution in an absorption tower, the absorbing solution that has absorbed carbon dioxide is sent from the absorption tower to a regeneration tower, and carbon dioxide is stripped from the absorbing solution in the regeneration tower and recovered by the absorption (for example, see Patent Documents 1 and 2).

[0003] Patent Document 1 discloses that a reboiler using steam as a heat source is attached to a regeneration tower, and the absorption liquid stored in the lower part of the regeneration tower is heated by the reboiler, thereby stripping carbon dioxide from the absorption liquid.

[0004] Patent Document 2 discloses that an aqueous solution of IPAE or a mixed aqueous solution of IPAE and TMDAH is used as an absorbing liquid, and a heat pump is used in a process for separating and recovering carbon dioxide absorbed in the absorbing liquid. A mixed heat medium of 20 mol % n-butane and 80 mol % n-pentane is used as the heat medium of the heat pump. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 11-267442 [Patent Document 2] JP 2015-131735 A Summary of the Invention [Problem to be solved by the invention]

[0006] In the carbon dioxide recovery device described in Patent Document 1, the dissipation of carbon dioxide is performed by heating with a reboiler that uses steam as a heat source, so thermal energy is required to generate steam, thermal energy to increase the temperature of the absorbing liquid, thermal energy to dissipate carbon dioxide from the absorbing liquid, thermal energy to compensate for heat loss due to evaporation of water from the absorbing liquid, etc. Therefore, a large amount of energy is required to dissipate the absorbed carbon dioxide, and energy costs are high.

[0007] In the carbon dioxide capture device described in Patent Document 2, the mixed heat medium is a mixed heat medium of n-butane and n-pentane, which have different boiling points. If the mixed heat medium leaks from the device, the heat medium with a lower boiling point is more likely to escape, and the mixed heat medium composition ratio in the device will change. Since it is difficult to confirm the composition ratio of the mixed heat medium remaining in the device by a simple method, if the mixed heat medium is refilled, it is highly likely to change from the original composition ratio. If the composition ratio changes, the dew point and boiling point also change, which causes the performance as designed to not be achieved. Therefore, if the mixed heat medium leaks from the device and decreases, it is necessary to drain all the mixed heat medium and then refill it, which significantly increases the cost and effort of maintenance. Furthermore, in the case of a mixed heat medium, resistance to mass transfer due to a concentration gradient occurs in phase change heat transfer, so that heat transfer performance generally tends to decrease, and there is a risk of energy efficiency decreasing.

[0008] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a carbon dioxide capture device that can reduce maintenance costs and effort, and can suppress the energy required to capture carbon dioxide. [Means for solving the problem]

[0009] The characteristic configuration of the carbon dioxide capture device according to the present invention for solving the above problems is as follows: A carbon dioxide recovery apparatus that recovers carbon dioxide by dissipating the carbon dioxide from an absorption liquid by heating the absorption liquid by a heating means, The heating means includes a heat exchange device that exchanges heat between the absorption liquid and a heat medium, The absorption liquid is an absorption liquid that dissipates the carbon dioxide at 80 to 100 ° C., The heat medium is a single heat medium having a critical temperature of the carbon dioxide dissipation temperature +10° C. or higher.

[0010] According to the carbon dioxide recovery device of this configuration, an absorbing liquid that dissipates carbon dioxide at a relatively low temperature of 80 to 100°C is used, and the absorbing liquid is heated by heat exchange with a heat medium in a heat exchanger. The heat medium used here is a heat medium whose critical temperature is the dissipation temperature of carbon dioxide +10°C or more. In this way, since the critical temperature of the heat medium is higher than the dissipation temperature of carbon dioxide, and there is a sufficient temperature difference (+10°C or more) between the dissipation temperature and the critical temperature, the absorbing liquid can be efficiently heated to the dissipation temperature by heat exchange with the heat medium. As a result, carbon dioxide can be dissipated and recovered with low energy compared to the one in which carbon dioxide is dissipated by heating with a reboiler using steam as a heat source, as in Patent Document 1. In addition, the heat medium used here is not a mixed heat medium in which two types of heat medium with different boiling points are mixed, as in Patent Document 2, but a single heat medium. Therefore, even if the heat medium leaks from the equipment, the heat medium composition ratio inside the equipment will not change, and if the heat medium leaks from the equipment and decreases, it is only necessary to refill the required amount, which reduces maintenance costs and labor compared to the case of a mixed heat medium. In addition, since there is no resistance to mass transfer due to a concentration gradient in phase change heat transfer as in the case of a mixed heat medium, there is no decrease in heat transfer performance and it is possible to prevent a decrease in energy efficiency. As a result, it is possible to reduce maintenance costs and labor, and it is possible to reduce the energy required to capture carbon dioxide.

[0011] In the carbon dioxide capture device according to the present invention, The absorbing liquid is preferably an amine liquid.

[0012] According to the carbon dioxide capture device having this configuration, since an amine liquid that is highly reactive with carbon dioxide is used as the absorbing liquid, carbon dioxide can be absorbed continuously and efficiently.

[0013] In the carbon dioxide capture device according to the present invention, The critical temperature is preferably 110° C. or higher.

[0014] In order to recover carbon dioxide by stripping it from the absorbing liquid, the absorbing liquid (amine liquid) needs to be heated to 80 to 100°C. If the critical temperature of the heat medium is lower than the carbon dioxide stripping temperature (80 to 100°C), the temperature of the heat medium will exceed the critical temperature in the heat exchange section of the heat exchanger, and there is a risk of poor heating efficiency. According to the carbon dioxide recovery device of this configuration, the critical temperature of the heat medium is set to 110°C or higher, which is sufficiently higher than the carbon dioxide stripping temperature (80 to 100°C). As a result, the temperature of the heat medium will not exceed the critical temperature in the heat exchange section of the heat exchanger, and as a result, the absorbing liquid can be efficiently heated in the heat exchanger.

[0015] In the carbon dioxide capture device according to the present invention, It is preferable that the heat transfer medium used does not contain a hydrocarbon.

[0016] According to the carbon dioxide recovery system of this configuration, a flammable hydrocarbon-based heat medium is not used, and a heat medium that does not contain hydrocarbons is used as the heat medium, so that it can be used in large-scale facilities such as plants.

[0017] In the carbon dioxide capture device according to the present invention, The heat medium is preferably at least one selected from the group consisting of R1224yd(Z), R1233zd(E), R1234ze(Z), R1336mzz(Z), R245fa, ammonia, and water.

[0018] According to the carbon dioxide capture device of this configuration, at least one heat medium selected from the above group is adopted. Among the above group, HFOs (hydrofluoroolefins) such as R1224yd(Z), R1233zd(E), R1234ze(Z), and R1336mzz(Z) have low global warming potential and ozone depletion potential, so that even if they are released into the atmosphere, the impact on the environment can be reduced. Among the above group, when R245fa is adopted as the heat medium, it has the advantage of being able to handle a wide range of temperatures since it can be used in high temperature ranges. Among the above group, ammonia and water are heat mediums (natural refrigerants) that exist naturally in nature, ammonia has the advantage of having a high COP, and water has the advantage of being inexpensive, non-toxic, and stable.

[0019] In the carbon dioxide capture device according to the present invention, It is preferable that the heating means further includes a reboiler for further heating the absorption liquid heated by the heat exchanger.

[0020] According to the carbon dioxide recovery system having this configuration, the absorption liquid heated by the heat exchanger is further heated by the reboiler, so that the carbon dioxide recovery efficiency can be further improved.

[0021] In the carbon dioxide capture device according to the present invention, The heat exchange device is preferably a heat pump including a compressor, a condenser, an expansion valve and an evaporator.

[0022] In the carbon dioxide capture system of this configuration, the heat medium compressed by the compressor heats the absorbing liquid (rich liquid) that has absorbed carbon dioxide and has a high carbon dioxide content when passing through the condenser. The heat medium then expands when passing through the thermal expansion valve, lowering its temperature. The lowered-temperature heat medium lowers the temperature of the absorbing liquid (lean liquid) that has dissipated carbon dioxide and has a low carbon dioxide content when passing through the evaporator. The heat medium, whose temperature has increased by absorbing heat from the lean liquid, is returned to the compressor. According to the carbon dioxide capture system of this configuration, the rich liquid can be heated while the lean liquid is cooled by a heat pump including a compressor, a condenser, an expansion valve, and an evaporator.

[0023] In the carbon dioxide capture device according to the present invention, an absorption tower containing the absorption liquid; A regeneration tower for regenerating the absorbing liquid; a first absorbing liquid supply pipe for supplying the absorbing liquid from the absorption tower to the regeneration tower; a second absorbing liquid supply pipe for supplying the regenerated absorbing liquid from the regenerator to the absorber; a heat exchanger that performs heat exchange between the absorbing liquid flowing through the first absorbing liquid supply pipe and the regenerated absorbing liquid flowing through the second absorbing liquid supply pipe; a condenser interposed in the first absorption liquid supply pipe at a position between the heat exchanger and the regeneration tower; It is preferable to have

[0024] According to the carbon dioxide recovery system of this configuration, the absorbing liquid that has absorbed carbon dioxide flowing through the first absorbing liquid supply pipe is heated in the heat exchanger by heat exchange with the regenerated absorbing liquid from the regenerator, and then is further heated in the condenser by heat exchange with the heat medium, thereby making it possible to further improve the carbon dioxide recovery efficiency.

[0025] In the carbon dioxide capture device according to the present invention, an absorption tower containing the absorption liquid; A regeneration tower for regenerating the absorbing liquid; a first absorbing liquid supply pipe for supplying the absorbing liquid from the absorption tower to the regeneration tower; a second absorbing liquid supply pipe for supplying the regenerated absorbing liquid from the regenerator to the absorber; a heat exchanger that performs heat exchange between the absorbing liquid flowing through the first absorbing liquid supply pipe and the regenerated absorbing liquid flowing through the second absorbing liquid supply pipe; an evaporator interposed in the second absorption liquid supply pipe at a position between the heat exchanger and the absorption tower; It is preferable to have

[0026] According to the carbon dioxide recovery system of this configuration, the regenerated absorbing liquid flowing through the second absorbing liquid supply pipe is cooled in the heat exchanger by heat exchange with the absorbing liquid that has absorbed carbon dioxide from the absorption tower, and then is further cooled in the evaporator by heat exchange with the heat medium, thereby obtaining an absorbing liquid that is more likely to absorb carbon dioxide.

[0027] In the carbon dioxide capture device according to the present invention, A regeneration tower for regenerating the absorbing liquid; A reflux pipe for refluxing a portion of the regenerated absorbing liquid extracted from the regenerator to the regenerator; Equipped with It is preferable that the condenser is disposed in the reflux pipe, and a reboiler is disposed in the reflux pipe so as to be located downstream of the condenser in the flow of the absorption liquid.

[0028] According to the carbon dioxide recovery system of this configuration, the absorption liquid flowing through the reflux pipe is first introduced into the condenser where it is heated, and then introduced into the reboiler where it is further heated. In this way, the absorption liquid is preheated in the condenser, so that the energy required to heat the absorption liquid in the reboiler can be reduced.

[0029] In the carbon dioxide capture device according to the present invention, An absorption tower that contains the absorption liquid, It is preferable that the evaporator is disposed in the absorption tower so as to be capable of exchanging heat with the absorbing liquid.

[0030] With the carbon dioxide recovery system of this configuration, the heat generated by the exothermic reaction occurring when carbon dioxide is absorbed into the absorbing liquid in the absorption tower can be used as a heat source for the endothermic reaction required to regenerate the absorbing liquid, thereby reducing the amount of heat input from outside and achieving energy savings. [Brief description of the drawings]

[0031] [Figure 1] FIG. 1 is a schematic diagram showing a schematic configuration of a carbon dioxide capture device according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram showing a schematic configuration of a carbon dioxide capture device according to a second embodiment of the present invention. [Diagram 3] FIG. 3 is a schematic diagram showing a schematic configuration of a carbon dioxide capture device according to a third embodiment of the present invention. [Figure 4] FIG. 4 is a graph showing the relationship between COP (coefficient of performance) and critical temperature. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] Hereinafter, the present invention will be described with reference to the drawings. However, the present invention is not intended to be limited to the embodiments described below or the configurations shown in the drawings.

[0033] First Embodiment <Outline of carbon dioxide capture device> FIG. 1 is a schematic diagram showing a schematic configuration of a carbon dioxide capture device 1A according to a first embodiment of the present invention. The carbon dioxide capture device 1A shown in FIG. 1 captures carbon dioxide from a carbon dioxide-containing gas (hereinafter referred to as a "treated gas") such as biogas or combustion exhaust gas through an absorption liquid. The carbon dioxide capture device 1A employs a chemical absorption method in which an alkaline compound in the absorption liquid is reacted with carbon dioxide to absorb carbon dioxide into the absorption liquid. In the following description, an absorption liquid having a high carbon dioxide content that has absorbed carbon dioxide is referred to as a "rich liquid" as necessary, and an absorption liquid having a low carbon dioxide content that has released the absorbed carbon dioxide is referred to as a "lean liquid".

[0034] <Absorption liquid> The absorbing liquid used in the present invention is not particularly limited as long as it can dissipate the absorbed carbon dioxide at a relatively low temperature of 80 to 100 ° C., but for example, a non-aqueous carbon dioxide absorbing liquid (amine liquid) disclosed in JP 2021-154237 A can be used. The carbon dioxide absorbing liquid contains a carbon dioxide chemically absorbing amine having a nitrogen-hydrogen bond and a tertiary multidentate amine not having a nitrogen-hydrogen bond, and further contains a diluent. The carbon dioxide chemically absorbing amine, the tertiary multidentate amine, and the diluent are usually liquid at room temperature, and the carbon dioxide absorbing liquid is obtained by mixing the carbon dioxide chemically absorbing amine and the tertiary multidentate amine and adding the diluent. In addition, as an absorbing liquid other than the amine liquid, for example, an alkaline solution, more preferably a caustic soda solution, can be used.

[0035] The combination of the carbon dioxide chemically absorbing amine, the tertiary multidentate amine, and the diluent is not particularly limited, but for example, a combination of any one or more of diethanolamine, dipropanolamine, dibutanolamine, N-methylethanolamine, N-ethylethanolamine, 3-methylamino-1-propanol, N-butylethanolamine, and N-propylethanolamine as the carbon dioxide chemically absorbing amine, any one or more of N-methyldiethanolamine, N-ethyldiethanolamine, and N-butyldiethanolamine as the tertiary multidentate amine, and dimethylsulfoxide, hexamethylphosphoric triamide, 1,3-dimethyl-2-imidazolidinone, N,N'-dimethylpropyleneurea, or tetramethylurea as the diluent is preferred.

[0036] <Overall configuration of carbon dioxide capture equipment> The carbon dioxide recovery system 1A includes an absorption tower 2, a regeneration tower 3, a rich liquid supply pipe 4, a lean liquid supply pipe 5, a heat exchanger 6, and a heating means 7. The rich liquid supply pipe 4 corresponds to the "first absorbing liquid supply pipe" of the present invention. The lean liquid supply pipe 5 corresponds to the "second absorbing liquid supply pipe" of the present invention.

[0037] <Absorption Tower> The absorption tower 2 brings the treatment gas into contact with a lean liquid capable of absorbing carbon dioxide, absorbs the carbon dioxide in the treatment gas into the lean liquid, generates a rich liquid, and stores and stores the generated rich liquid. A treatment gas inlet pipe 10 is connected to the lower part of the absorption tower 2 for introducing the treatment gas into the tower. A decarbonated gas outlet pipe 11 is connected to the top of the absorption tower 2 for discharging the decarbonated gas after carbon dioxide is recovered from the treatment gas. A lean liquid sprayer 12 for spraying the lean liquid is installed in the upper part of the absorption tower 2, and an absorption tower packing material 13 is installed in the intermediate part between the lean liquid sprayer 12 and the lower part of the absorption tower 2. The absorption tower packing material 13 is installed to increase the efficiency of gas-liquid contact. The absorption tower packing material 13 may be made of either metal or resin, and in order to increase the gas-liquid contact area, for example, irregular packing such as Raschig rings, Berl saddles, and Paul rings is used, and it may also have a porous structure or a honeycomb structure. The absorption tower 2 may have a structure similar to a scrubber that absorbs carbon dioxide in the treated gas while circulating a large amount of absorption liquid, and may also be a spray tower, plate tower, or the like that does not have an absorption tower filler 13.

[0038] <Regeneration Tower> The regenerator 3 strips carbon dioxide from the rich liquid supplied from the absorption tower 2 to regenerate the rich liquid into lean liquid. A recovered gas discharge pipe 14 for discharging the recovered gas containing carbon dioxide is connected to the top of the regenerator 3. A rich liquid sprayer 15 for spraying the rich liquid is installed in the upper part of the regenerator 3, and a regenerator filler 16 is installed in the intermediate part between the rich liquid sprayer 15 and the lower part of the regenerator 3. As the regenerator filler 16, the same one as the above-mentioned absorption tower filler 13 is used.

[0039] A gas-liquid separator 17 is provided in the middle of the recovered gas discharge pipe 14 to separate the condensate generated when the recovered gas containing carbon dioxide is cooled by a cooling means (not shown) from the carbon dioxide-based gas. The condensate separated in the gas-liquid separator 17 is sent to the rich liquid sprayer 15 via a return pipe 18. The uncondensed carbon dioxide-based gas separated in the gas-liquid separator 17 is recovered via the recovered gas discharge pipe 14 and temporarily stored in, for example, a gas holder (not shown), and then effectively utilized. The rich liquid sprayer 15, the regeneration tower packing 16, the gas-liquid separator 17, and the return pipe 18 attached to the regeneration tower 3 may have any configuration and may be selected as appropriate.

[0040] <Rich liquid supply pipe> The rich liquid supply pipe 4 connects the bottom of the absorption tower 2 to the rich liquid sprayer 15 in order to feed the rich liquid that has absorbed carbon dioxide in the absorption tower 2 from the absorption tower 2 to the regeneration tower 3. A rich liquid pressure-feed pump (not shown) is interposed in the rich liquid supply pipe 4, and the rich liquid is pressure-feed from the bottom of the absorption tower 2 to the rich liquid sprayer 15 by the rich liquid pressure-feed pump.

[0041] <Lean liquid supply pipe> The lean liquid supply pipe 5 connects the bottom of the regenerator 3 to the lean liquid sprayer 12 in order to feed the lean liquid that has been regenerated in the regenerator 3 and released carbon dioxide from the regenerator 3 to the absorption tower 2. A lean liquid pressure feed pump (not shown) is interposed in the lean liquid supply pipe 5, and the lean liquid is pressure-fed from the bottom of the regenerator 3 to the lean liquid sprayer 12 by the lean liquid pressure feed pump.

[0042] <Heat exchanger> The rich liquid supply pipe 4 and the lean liquid supply pipe 5 are disposed in such a manner that they cross each other via a heat exchanger 6. The heat exchanger 6 is of a type that performs heat exchange between the rich liquid flowing through the rich liquid supply pipe 4 and the lean liquid flowing through the lean liquid supply pipe 5. Note that there are cases in which heat exchange (heating, cooling) is not performed between the rich liquid and the lean liquid, in which case the heat exchanger 6 is omitted.

[0043] <Heating means (heat exchange device)> The heating means 7 includes a heat exchanger 20 and heats the rich liquid. The heat exchanger 20 is a heat pump including a compressor 21, a condenser 22, an expansion valve 23, an evaporator 24, a heat medium forward pipe 25, and a heat medium return pipe 26 (hereinafter referred to as "heat pump 20").

[0044] The condenser 22 is disposed in the rich liquid supply pipe 4 at a position between the heat exchanger 6 and the rich liquid sprayer 15 (regeneration tower 3), and exchanges heat between the compressed and heated heat medium and the rich liquid.

[0045] The evaporator 24 is disposed in the lean liquid supply pipe 5 at a position between the heat exchanger 6 and the lean liquid sprayer 12 (absorption tower 2), and exchanges heat between the heat medium, the temperature of which has been reduced by expansion, and the lean liquid.

[0046] In the heat pump 20, in order to circulate the heat medium between the condenser 22 and the evaporator 24, the condenser 22 and the evaporator 24 are connected by a heat medium forward pipe 25 and a heat medium return pipe 26, thereby forming a heat medium circulation circuit 27. A compressor 21 that increases the temperature of the heat medium by compressing it is disposed in the heat medium forward pipe 25. An expansion valve 23 that decreases the temperature of the compressed heat medium by expanding it is disposed in the heat medium return pipe 26. The heat medium flowing through the heat medium circulation circuit 27 repeatedly flows so as to pass through the compressor 21, the condenser 22, the expansion valve 23, and the evaporator 24 in sequence.

[0047] The heat medium used in the heat pump 20 is, for example, a fluid that can be used to regenerate the lean liquid in the regeneration tower 3, recover the heat remaining after heat exchange in the heat exchanger 6 as latent heat of evaporation by evaporating it in the evaporator 24, and use the condensation heat generated by condensing it in the condenser 22 as a heat source for heating the rich liquid.

[0048] As described above, in this embodiment, an amine liquid that dissipates carbon dioxide at 80 to 100°C is used as the absorbing liquid. Therefore, in order to dissipate and recover carbon dioxide from the absorbing liquid, it is necessary to heat the absorbing liquid (amine liquid) to 80 to 100°C. If the critical temperature of the heat medium is lower than the dissipation temperature of carbon dioxide (80 to 100°C), the temperature of the heat medium may exceed the critical temperature in the heat exchange section (condenser 22) of the heat pump 20, and the heating efficiency may deteriorate. Therefore, it is preferable that the critical temperature of the heat medium used in the heat pump 20 is 110°C or higher. If the critical temperature is sufficiently higher than the dissipation temperature of carbon dioxide (80 to 100°C), the temperature of the heat medium will not exceed the critical temperature in the heat exchange section (condenser 22) of the heat pump 20, and as a result, the absorbing liquid can be efficiently heated in the heat pump 20.

[0049] The heat medium used in the heat pump 20 is preferably a heat medium that does not contain hydrocarbons and that easily ignites if it leaks to the outside. Specifically, it is preferably at least one selected from the group consisting of R1224yd(Z), R1233zd(E), R1234ze(Z), R1336mzz(Z), R245fa, ammonia, and water.

[0050] 4 is a graph showing the relationship between COP (coefficient of performance) and critical temperature. As shown in FIG. 4, R1224yd(Z), R1233zd(E), R1234ze(Z), R1336mzz(Z), R245fa, ammonia, and water all have critical temperatures of 110° C. or higher, and are suitable as heat transfer media for use in the heat pump 20.

[0051] Here, R1224yd(Z), R1233zd(E), R1234ze(Z), R1336mzz(Z) and R245fa are refrigerant numbers that indicate the type of refrigerant (heat medium). R1224yd(Z) is (Z)-1-chloro-2,3,3,3-tetrafluoropropene. R1233zd(E) is trans-1-chloro-3,3,3-trifluoropropene. R1234ze(Z) is cis-1,3,3,3-tetrafluoropropene. R1336mzz(Z) is (Z)-1,1,1,4,4,4-hexafluoro-2-butene. R245fa is 1,1,1,3,3-pentafluoropropane.

[0052] Among the above group, HFOs (hydrofluoroolefins) such as R1224yd(Z), R1233zd(E), R1234ze(Z), and R1336mzz(Z) have low global warming potential and ozone depletion potential, so that even if they are released into the atmosphere, the impact on the environment can be reduced. Among the above group, when R245fa is used as a heat transfer medium, it has the advantage of being able to handle a wide range of temperatures since it can be used in high temperature ranges. Among the above group, ammonia and water are heat transfer mediums (natural refrigerants) that exist naturally in nature, and ammonia has the advantage of having a high COP, and water has the advantage of being inexpensive, non-toxic, and stable.

[0053] <Heating means (reboiler)> As shown in FIG. 1, the heating means 7 further includes a reboiler 30, which further heats the absorbing liquid heated by the heat pump 20. The reboiler 30 is interposed in the middle of a reflux pipe 31 connected to the lower part of the regenerator 3 in a form branched from the lean liquid supply pipe 5 in order to reflux a part of the absorbing liquid after regeneration extracted from the regenerator 3 to the regenerator 3. The reboiler 30 is configured such that steam generated by utilizing heat recovered from the combustion exhaust gas by a boiler attached to a waste combustion furnace, for example, is introduced and discharged, and the absorbing liquid can be heated using the steam as a heat source. The heating means 7 is configured such that the absorbing liquid in the regenerator 3 is heated by refluxing the absorbing liquid that has absorbed the heat of steam by heat exchange between the absorbing liquid introduced into the reboiler 30 via the reflux pipe 31 and the steam introduced into the reboiler 30 through the reflux pipe 31 into the inside of the regenerator 3. The heat source for heating the absorption liquid is not limited to the steam described above. For example, exhaust gas after dust removal treatment, which is sent from an exhaust gas treatment facility (not shown) that treats combustion exhaust gas, may be connected to the reboiler 30 so as to be able to be introduced and discharged, and the absorption liquid may be heated using the exhaust heat of the exhaust gas.

[0054] The operation of the carbon dioxide recovery device 1A configured as described above will be described. First, in the absorption tower 2, the treated gas supplied to the inside of the tower through the treated gas introduction pipe 10 rises inside the absorption tower 2, and the lean liquid supplied from the lean liquid sprayer 12 falls inside the absorption tower 2. In this process, the treated gas and the lean liquid come into countercurrent contact. On the surface of the absorption tower packing 13, the lean liquid flows down, and the flowing down lean liquid comes into gas-liquid contact with the treated gas rising inside the absorption tower 2. This improves the contact efficiency between the rising treated gas and the descending lean liquid, and promotes the absorption of carbon dioxide by the lean liquid. When the lean liquid flows down inside the absorption tower 2, an exothermic reaction occurs as it absorbs carbon dioxide in the treated gas, and the temperature of the lean liquid rises.

[0055] In the absorption tower 2, the lean liquid absorbs carbon dioxide to become a rich liquid having a high carbon dioxide content, and the rich liquid is stored at the bottom of the tower. On the other hand, the decarbonated gas after carbon dioxide is recovered from the treated gas rises toward the top of the absorption tower 2 and is discharged to the outside through the decarbonated gas discharge pipe 11.

[0056] The rich liquid stored in the bottom of the absorption tower 2 is supplied to a rich liquid sprayer 15 in the regeneration tower 3 via a rich liquid supply pipe 4. A heat exchanger 6 and a condenser 22 are sequentially installed in the rich liquid supply pipe 4 from the upstream side to the downstream side of the rich liquid flow, and the rich liquid is heated by heat exchange with the lean liquid from the regeneration tower 3 in the heat exchanger 6, and then is further heated by heat exchange with a heat medium in the condenser 22. This can further improve the carbon dioxide recovery efficiency.

[0057] In the regeneration tower 3, the rich liquid supplied from the rich liquid sprayer 15 descends inside the regeneration tower 3 and is stored at the bottom of the tower, and the stored absorption liquid (a mixture of the rich liquid and the lean liquid) is heated by the reboiler 30. As a result, carbon dioxide gas is dissipated from the absorption liquid and separated from the absorption liquid.

[0058] The carbon dioxide gas separated from the absorbing liquid is mixed with the solute and the vapor of the solvent of the absorbing liquid to become a mixed gas, which rises inside the regenerator 3. This mixed gas is cooled by a cooling means (not shown) while passing through the recovered gas discharge pipe 14 from the top of the regenerator 3, and then the solute and the vapor of the solvent are condensed to become a condensate, and this condensate and the uncondensed carbon dioxide-based gas mainly composed of carbon dioxide gas are separated by the gas-liquid separator 17. Then, the condensate is reintroduced into the regenerator 3 via the return pipe 18 and the rich liquid sprayer 15. Meanwhile, the uncondensed carbon dioxide-based gas is recovered via the recovered gas discharge pipe 14.

[0059] A part of the absorption liquid extracted from the bottom of the regenerator 3 is extracted through the lean liquid supply pipe 5 and the reflux pipe 31, introduced into the reboiler 30, heated in the reboiler 30, and then introduced into the regenerator 3. Meanwhile, the remaining part of the absorption liquid extracted from the bottom of the regenerator 3 is supplied as a lean liquid to the lean liquid sprayer 12 in the absorption tower 2 through the lean liquid supply pipe 5. A heat exchanger 6 and an evaporator 24 are interposed in the lean liquid supply pipe 5 from the upstream side to the downstream side of the lean liquid flow, and the lean liquid is cooled by heat exchange with the rich liquid from the absorption tower 2 in the heat exchanger 6, and then further cooled by heat exchange with the heat medium in the evaporator 24. This makes it possible to obtain an absorption liquid that is more likely to absorb carbon dioxide.

[0060] Next, the flow of the heat medium in the heat pump 20 will be described starting from the expansion valve 23. The heat medium expanded by the expansion valve 23 and lowered in temperature exchanges heat with the lean liquid while moving through the evaporator 24, and while cooling the lean liquid, receives the residual heat when the lean liquid is heated when separating carbon dioxide, and evaporates and vaporizes. The heat medium is then compressed by the compressor 21 and rises to a predetermined temperature. Then, the heat medium whose temperature has risen exchanges heat with the rich liquid while moving through the condenser 22, and heats the rich liquid, and changes to a liquid phase by removing the heat. The cooled heat medium reaches the expansion valve 23 again. Through the above-mentioned route, the heat medium circulates in the heat medium circulation circuit 27, and while cooling the lean liquid to an appropriate temperature, heats the rich liquid to an appropriate temperature.

[0061] In the carbon dioxide recovery system 1A of the first embodiment, since heat recovery is performed using the heat pump 20 together with the heat exchanger 6, heat recovery can be performed efficiently and energy saving can be achieved. Moreover, in the carbon dioxide recovery system 1A, the absorption liquid heated by the heat pump 20 is further heated by the reboiler 30, so that the carbon dioxide recovery efficiency can be further improved.

[0062] In the carbon dioxide recovery device 1A of the first embodiment, an amine liquid that dissipates carbon dioxide at a relatively low temperature of 80 to 100 ° C. is used as the absorbing liquid, and since there is a sufficient temperature difference (+10 ° C. or more) between the critical temperature of the heat medium and the dissipation temperature, the absorbing liquid can be efficiently heated to the dissipation temperature by heat exchange with the heat medium. In addition, the heat medium is a single heat medium. Therefore, it is a single heat medium. Therefore, even if the heat medium leaks from a device such as the condenser 22, the heat medium composition ratio in the device does not change, and when the heat medium leaks from the device and decreases, it is only necessary to add the required amount, and the maintenance cost and labor can be reduced compared to the case of a mixed heat medium. In addition, since there is no resistance to mass transfer due to a concentration gradient in phase change heat transfer as in the case of a mixed heat medium, the heat transfer performance does not decrease, and the decrease in energy efficiency can be prevented in advance. As a result, the maintenance cost and labor can be reduced, and the energy required to recover carbon dioxide can be suppressed.

[0063] Second Embodiment 2 is a schematic diagram showing a schematic configuration of a carbon dioxide capture device 1B according to a second embodiment of the present invention. In the second embodiment, the same or similar parts as those in the first embodiment are denoted by the same reference numerals in the drawing, and detailed description thereof is omitted. In the following, the description will focus on parts unique to the second embodiment (the same applies to the third embodiment described later).

[0064] In the carbon dioxide recovery apparatus 1A of the first embodiment shown in Fig. 1, a condenser 22 is interposed in the rich liquid supply pipe 4 at a position between the heat exchanger 6 and the rich liquid sprayer 15. In contrast, in the carbon dioxide recovery apparatus 1B of the second embodiment shown in Fig. 2, the condenser 22 is interposed in the reflux pipe 31. Here, a reboiler 30 is interposed in the reflux pipe 31 so as to be located downstream of the absorption liquid flow with respect to the condenser 22. The rest is the same as the first embodiment.

[0065] According to the carbon dioxide recovery system 1B of the second embodiment, the absorption liquid flowing through the reflux pipe 31 is first introduced into the condenser 22 and heated, and then introduced into the reboiler 30 and further heated. Since the absorption liquid is heated in advance in the condenser 22 in this manner, the energy required to heat the absorption liquid in the reboiler 30 can be reduced.

[0066] Third Embodiment Fig. 3 is a schematic diagram showing a schematic configuration of a carbon dioxide recovery apparatus 1C according to a third embodiment of the present invention. As shown in Fig. 3, in the carbon dioxide recovery apparatus 1C according to the third embodiment, an evaporator 24 is disposed inside the absorption tower 2 so as to be capable of heat exchange with the absorbing liquid whose temperature has increased due to an exothermic reaction accompanying the absorption of carbon dioxide in the treatment gas. The rest is the same as in the first embodiment.

[0067] According to the carbon dioxide recovery apparatus 1C of the third embodiment, the heat generated by the exothermic reaction occurring when carbon dioxide is absorbed into the absorbing liquid in the absorption tower 2 can be utilized as a heat source for the endothermic reaction required to regenerate the absorbing liquid, thereby reducing the amount of heat input from the outside and achieving energy savings.

[0068] The carbon dioxide capture device of the present invention has been described above based on several embodiments. However, the present invention is not limited to the configurations described in the above embodiments, and the configuration can be appropriately changed within the scope of the spirit of the present invention, such as by appropriately combining the configurations described in each embodiment. [Industrial Applicability]

[0069] The carbon dioxide capture device of the present invention can be used in applications such as separating and capturing carbon dioxide contained in exhaust gas generated by the combustion of fossil fuels in thermal power plants, steel mills, oil refineries, etc.; carbon dioxide contained in exhaust gas generated by the combustion of off-gas in hydrogen production facilities; carbon dioxide contained in exhaust gas generated by the combustion of waste in general waste incineration facilities; and carbon dioxide contained in exhaust gas generated by the combustion of biomass fuels in biomass power generation facilities. [Explanation of symbols]

[0070] 1A~1C Carbon dioxide capture device 2. Absorption tower 3 Regeneration Tower 4 Rich liquid supply pipe (first absorption liquid supply pipe) 5 Lean liquid supply pipe (second absorption liquid supply pipe) 6 Heat exchanger 7 Heating means 20 Heat exchanger (heat pump) 21 Compressor 22 Condenser 23 Expansion valve 24 Evaporator 30 Reboiler

Claims

1. A carbon dioxide recovery apparatus that recovers carbon dioxide by dissipating the carbon dioxide from an absorption liquid by heating the absorption liquid by a heating means, The heating means includes a heat exchange device that exchanges heat between the absorption liquid and a heat medium, The absorbing liquid is an absorbing liquid that dissipates the carbon dioxide at 80 to 100° C., The carbon dioxide recovery device, wherein the heat medium is a single heat medium having a critical temperature of the carbon dioxide dissipation temperature + 10°C or higher.

2. The carbon dioxide capture device according to claim 1 , wherein the absorbing liquid is an amine liquid.

3. The carbon dioxide recovery device according to claim 1 , wherein the critical temperature is 110° C. or higher.

4. The carbon dioxide recovery system according to claim 1 , wherein the heat medium is a heat medium that does not contain a hydrocarbon.

5. The carbon dioxide recovery device according to claim 4, wherein the heat medium is at least one selected from the group consisting of R1224yd (Z), R1233zd (E), R1234ze (Z), R1336mzz (Z), R245fa, ammonia, and water.

6. The carbon dioxide recovery apparatus according to any one of claims 1 to 5, wherein the heating means further includes a reboiler that further heats the absorption liquid heated by the heat exchanger.

7. The carbon dioxide recovery apparatus according to any one of claims 1 to 5, wherein the heat exchange device is a heat pump including a compressor, a condenser, an expansion valve, and an evaporator.

8. an absorption tower containing the absorption liquid; A regeneration tower for regenerating the absorbing liquid; a first absorbing liquid supply pipe for supplying the absorbing liquid from the absorption tower to the regeneration tower; a second absorbing liquid supply pipe for supplying the regenerated absorbing liquid from the regenerator to the absorber; a heat exchanger that performs heat exchange between the absorbing liquid flowing through the first absorbing liquid supply pipe and the regenerated absorbing liquid flowing through the second absorbing liquid supply pipe; a condenser interposed in the first absorption liquid supply pipe at a position between the heat exchanger and the regeneration tower; The carbon dioxide capture device according to claim 7 .

9. an absorption tower containing the absorption liquid; A regeneration tower for regenerating the absorbing liquid; a first absorbing liquid supply pipe for supplying the absorbing liquid from the absorption tower to the regeneration tower; a second absorbing liquid supply pipe for supplying the regenerated absorbing liquid from the regenerator to the absorber; a heat exchanger that performs heat exchange between the absorbing liquid flowing through the first absorbing liquid supply pipe and the regenerated absorbing liquid flowing through the second absorbing liquid supply pipe; an evaporator interposed in the second absorption liquid supply pipe at a position between the heat exchanger and the absorption tower; The carbon dioxide capture device according to claim 7 .

10. A regeneration tower for regenerating the absorbing liquid; A reflux pipe for refluxing a portion of the regenerated absorbing liquid extracted from the regenerator to the regenerator; Equipped with 8. The carbon dioxide recovery system according to claim 7, wherein the condenser is disposed in the reflux pipe, and a reboiler is disposed in the reflux pipe so as to be located downstream of the condenser in the flow of the absorption liquid.

11. An absorption tower that contains the absorption liquid, The carbon dioxide recovery system according to claim 7, wherein the evaporator is disposed in the absorption tower so as to be capable of exchanging heat with the absorbing liquid.

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