JP2007000841A - System for and method of recovering carbon dioxide - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a system for recovering carbon dioxide, in which the pressure in a regeneration apparatus can be reduced efficiently and steam to be released together with carbon dioxide can be recovered as thermal energy by reducing the pressure in the regeneration apparatus and consequently the energy conservation of which can be promoted and to provide a method for recovering carbon dioxide. <P>SOLUTION: The system for recovering carbon dioxide is provided with: an absorption column 100 for absorbing carbon dioxide in exhaust gas 103 in a liquid absorbent 150; a regeneration column 110 for regenerating the liquid absorbent 150 by releasing carbon dioxide from the carbon dioxide-absorbed liquid absorbent 150; suction apparatuses 121a, 121b, 121c for sucking gasses in the regeneration column 110 by making good use of a flow of a liquid 123 circulating through a liquid circulating line 133; and a pressure reducing apparatus 120 for reducing the pressure in the regeneration column 110 to recover gasses. As a result, the energy conservation of the system can be promoted. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a carbon dioxide recovery system and a carbon dioxide recovery method for recovering carbon dioxide and the like contained in exhaust gas from a boiler, a waste incinerator, and the like of a thermal power plant.

  In recent years, the problem of global warming due to the greenhouse effect of carbon dioxide, which is a combustion product of fossil fuel, has been increasing. In the Kyoto Protocol of the United Nations Framework Convention on Climate Change, Japan's goal of reducing greenhouse gas emissions is to achieve the 1990 ratio of minus 6% between 2008 and 2012.

  Against this background, a system for recovering carbon dioxide by using, for example, an aqueous solution of an amine compound, which is an alkaline substance, as an absorbing solution is proposed. (For example, refer to Patent Document 1).

  Here, FIG. 3 shows an outline of a conventional carbon dioxide recovery system 200 that recovers carbon dioxide using an aqueous amine solution as an absorbing solution.

  In the conventional carbon dioxide recovery system 200 shown in FIG. 3, exhaust gas 201 discharged by burning fossil fuel is guided to an absorption tower 203 by a gas blower 202. An absorption liquid 204 having a temperature of about 50 ° C. is supplied to the upper portion of the absorption tower 203, and the supplied absorption liquid 204 comes into contact with the introduced exhaust gas 201 and absorbs carbon dioxide in the exhaust gas 201. On the other hand, the remaining exhaust gas 201 having absorbed the carbon dioxide in the absorbing liquid 204 is released from the upper part of the absorption tower 203 to the atmosphere.

  The absorption liquid 204 that has absorbed carbon dioxide is extracted from the lower part of the absorption tower 203 and guided to the heat exchanger 206 by the pump 205 and further to the regeneration tower 207.

  The absorbing liquid 204 guided to the regeneration tower 207 is heated to a temperature of about 120 ° C. by the steam 209 of the heater 208 and disturbed. Then, carbon dioxide is dissipated from the absorbing liquid 204 and regenerated into the absorbing liquid 204 that can absorb carbon dioxide again. The regenerated absorption liquid 204 is returned to the upper part of the absorption tower 203 by the circulation pump 210 through the heat exchanger 206 and the cooler 211. On the other hand, the carbon dioxide released from the absorbing liquid 204 is guided to the separator 213 through the cooler 212, and is recovered after moisture is removed by the separator 213.

In the conventional carbon dioxide recovery system 200 configured as described above, the absorption liquid 204 is regenerated in the regeneration tower 207 by heating the absorption liquid 204 to about 120 ° C. under almost atmospheric pressure.
JP 2002-126439 A

  In the conventional carbon dioxide recovery system 200 described above, since the enormous absorption liquid 204 circulating in the regeneration tower 207 is regenerated under atmospheric pressure, it is necessary to heat the absorption liquid 204 to a high temperature of about 120 ° C. was there. For this reason, a large amount of exhaust heat from the high-temperature steam 209 is used, and it is difficult to improve the thermal efficiency of the system.

  On the other hand, in order to lower the heating temperature of the absorbent 204 and release carbon dioxide, it is necessary to reduce the internal pressure of the regeneration tower 207. However, if the internal pressure of the regeneration tower 207 is reduced using, for example, a vacuum pump, a large amount of water vapor is removed as moisture by the separator 213, leading to a large loss of heat energy. Further, when the vacuum pump is driven, the vacuum pump generates heat and releases heat energy to the outside. Therefore, it is difficult to improve the thermal efficiency of the system.

  Accordingly, the present invention has been made to solve the above-described problems, and can effectively reduce the pressure in the regenerator, and the water vapor released together with carbon dioxide by depressurizing the regenerator. It is an object of the present invention to provide a carbon dioxide recovery system and a carbon dioxide recovery method that can recover energy as thermal energy and promote energy saving as a system.

  In order to achieve the above object, a carbon dioxide recovery system of the present invention comprises a gas inlet, an absorbing liquid inlet for absorption, a remaining gas outlet and an absorbent outlet, and a gas introduced from the gas inlet. An absorption device that causes gas-liquid contact with the absorption liquid introduced from the absorption liquid inlet for absorption and causes the absorption liquid to absorb carbon dioxide in the gas; an absorption liquid introduction port for regeneration; a regeneration absorption liquid discharge port; A regenerator comprising a carbon dioxide outlet and regenerating the absorbent by releasing carbon dioxide from the absorbent that has absorbed the carbon dioxide; and the regenerator for absorbing liquid discharged from an absorbent outlet of the absorber A first absorbing liquid line that leads to the regenerating absorbent inlet of the regenerating apparatus, and a second absorbing liquid that guides the absorbent discharged from the regenerating absorbent outlet of the regenerating apparatus to the absorbing absorbent inlet of the absorbing apparatus Line and predetermined temperature A liquid circulation line that circulates a liquid, and a flow-out device that draws a gas in the regeneration device using a flow of the liquid that circulates in the liquid circulation line, decompressing the regeneration device, and collecting the gas And a pressure reducing device.

  According to this carbon dioxide recovery system, the gas and the absorption liquid are guided to the absorption device and brought into gas-liquid contact with each other, the carbon dioxide contained in the gas is absorbed in the absorption liquid, and the regenerator is decompressed by the decompression device. Carbon dioxide can be released from the absorbing solution to regenerate the absorbing solution. Moreover, the energy used for pressure reduction can be reduced by providing the flow-out apparatus which flows the gas in a reproduction | regeneration apparatus using the flow of the liquid which circulates through a liquid circulation line.

  In the carbon dioxide recovery method of the present invention, the gas and the absorption liquid are guided to an absorption device, the gas and the absorption liquid are brought into gas-liquid contact, and the absorption liquid absorbs carbon dioxide in the gas; The absorption liquid that has absorbed carbon dioxide in the absorption process is guided to a regenerator, the regeneration process for regenerating the absorption liquid by releasing the carbon dioxide from the absorption liquid, the liquid at a predetermined temperature is circulated, and the circulating liquid And a decompression recovery step of recovering the gas by depressurizing the inside of the regenerator by flowing the gas in the regenerator using the flow of gas.

  According to this carbon dioxide recovery method, in the absorption process, the gas and the absorption liquid are guided to the absorption device and brought into gas-liquid contact with each other, and the carbon dioxide contained in the gas is absorbed in the absorption liquid, and the pressure is reduced by the vacuum recovery process. The regenerating apparatus can regenerate the absorbing liquid by releasing carbon dioxide from the absorbing liquid. Moreover, the energy used for pressure_reduction | reduced_pressure can be reduced by providing the pressure reduction recovery process which draws the gas in a reproduction | regeneration apparatus using the flow of the circulating liquid.

  According to the carbon dioxide recovery system and the carbon dioxide recovery method of the present invention, the pressure in the regenerator can be efficiently reduced, and the water vapor released together with carbon dioxide by reducing the pressure in the regenerator is converted into thermal energy. As a system, energy saving as a system can be promoted.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 shows an outline of a carbon dioxide recovery system 10 according to a first embodiment of the present invention.

  The carbon dioxide recovery system 10 includes an absorption tower 100 for bringing the introduced exhaust gas 103 and the absorption liquid 150 into gas-liquid contact, and a regeneration tower for regenerating the absorption liquid 150 by releasing carbon dioxide from the absorption liquid 150 that has absorbed carbon dioxide. 110, a decompression device 120 that reduces the internal pressure of the regeneration tower 110, and an absorption liquid line 130 that guides the absorption liquid 150 discharged from the absorption liquid discharge port 101 of the absorption tower 100 to the regeneration absorption liquid inlet 111 of the regeneration tower 110. And an absorption liquid line 131 that leads the absorption liquid 150 discharged from the regeneration absorption liquid discharge port 112 of the regeneration tower 110 to the absorption liquid inlet for absorption 102 of the absorption tower 100, and carbon dioxide provided at the upper part of the regeneration tower 110. Carbon dioxide that guides carbon dioxide, water vapor, and the like in the regeneration tower 110 from the outlet 113 to the flow-out devices 121a, 121b, 121c,. Mainly composed of a lead-out line 132, a liquid circulation line 133 that circulates the liquid 123 in the decompression device 120 via the flow-out devices 121a, 121b, 121c..., And a controller 140 that controls each pump, each device, and the like. Has been. The carbon dioxide recovery system 10 also includes a liquid outlet line 134 that guides the liquid 123 in the decompression device 120 to the absorbing liquid line 131. The liquid outlet line 134 may be configured to communicate with the bottom of the regeneration tower 110.

  In FIG. 1, the control unit 140 is electrically connected to each pump, each component device, and the like, which will be described later, but the connection lines are not shown for clarity of the drawing.

  First, a reflux path for refluxing the absorbing liquid 150 to the absorption tower 100 and the regeneration tower 110 will be described.

  Under the absorption tower 100, an exhaust gas inlet 104 is provided for guiding the exhaust gas 103 containing carbon dioxide discharged from a boiler of a thermal power plant or a municipal waste incineration plant into the absorption tower 100. The gas introduced into the exhaust gas inlet 104 is not limited to the exhaust gas 103 discharged from a boiler of a thermal power plant, a municipal waste incinerator, or the like. For example, natural gas containing carbon dioxide mined at a natural gas mine But you can. When this natural gas is introduced into the absorption tower 100, carbon dioxide can be separated from the natural gas, so that a high concentration of natural gas can be recovered.

  In addition, a gas blower 105 for sending the exhaust gas 103 into the absorption tower 100 is connected to the exhaust gas inlet 104. In the upper part of the absorption tower 100, there is provided an absorption liquid inlet 102 for absorption through which the absorption liquid 150 discharged from the regeneration absorption liquid outlet 112 of the regeneration tower 110 is introduced. The absorption liquid introduction port 102 for absorption is provided with an absorption liquid ejection portion 106 that ejects the absorption liquid 150. Further, inside the absorption tower 100, there is provided a filler 107 that mainly makes gas-liquid contact between the absorption liquid 150 ejected from the absorption liquid ejection section 106 and the exhaust gas 103 introduced into the absorption tower 100. The upper end of the absorption tower 100 functions as a remaining gas discharge port, and is provided with an exhaust port 108 for exhausting the exhaust gas 103 having absorbed carbon dioxide into the atmosphere by passing through the filler 107. ing.

  Here, the absorbing liquid 150 ejected from the absorbing liquid ejecting section 106 is preferably ejected uniformly. For example, the absorbing liquid ejecting section 106 is provided with a spray nozzle or the like that provides a predetermined spray particle size and spray pattern. It may be used. In addition, when the absorption liquid 150 can be dispersed substantially uniformly in the absorption tower 100 by the configuration of the absorption liquid inlet for absorption 102, the absorption liquid ejection part 106 may not be provided.

  The filler 107 may be, for example, a material having a porous structure, a honeycomb structure, or the like and having an action of disturbing the absorbing liquid 150 passing through the filler 107. Moreover, the filler 107 may be installed in multiple stages in the absorption tower 100. In the case where the fillers 107 are installed in multiple stages, for example, an absorbing liquid ejection unit 106 that ejects the absorbing liquid 150 may be provided corresponding to each stage. If the gas-liquid contact between the exhaust gas 103 and the absorption liquid 150 can be performed efficiently in the absorption tower 100, the absorption tower 100 can be configured without installing the filler 107.

  Furthermore, an absorption liquid discharge port 101 for discharging the absorption liquid 150 that has absorbed carbon dioxide is provided at the bottom of the absorption tower 100. The absorption liquid discharge port 101 is connected to one end of an absorption liquid line 130 provided with a liquid feed pump 160. The other end of the absorbent liquid line 130 is connected to the regeneration absorbent inlet 111 for the regeneration tower 110.

  A regeneration absorption liquid discharge port 112 for discharging the regenerated absorption liquid 150 is provided at the bottom of the regeneration tower 110. The regeneration absorbing liquid discharge port 112 is connected to one end of an absorbing liquid line 131 provided with a liquid feeding pump 161 and a cooler 170. The other end of the absorption liquid line 131 is connected to the absorption liquid inlet for absorption 102 of the absorption tower 100. The cooler 170 cools the absorption liquid 150 that circulates through the absorption liquid line 131, and includes a heat exchanger or the like. In the cooler 170, for example, seawater or water may be used as a cooling medium for recovering heat from the absorbing liquid 150.

  In addition, the regeneration tower 110 is provided with a heater 171 that heats the absorption liquid 150 accumulated at the bottom using, for example, the heat of the exhaust gas 103. As the regeneration tower 110, for example, a flushing tank or a tank provided with a filler as in the absorption tower 100 is used. Furthermore, when supplying the absorption liquid 150 into the regeneration tower 110, for example, the absorption liquid 150 may be atomized and supplied into the regeneration tower 110. In this case, it is preferable to provide an absorbing liquid ejection part (not shown) for atomizing the absorbing liquid 150 at the upper part of the regeneration tower 110. The absorbing liquid jetting unit is constituted by, for example, a spray nozzle, a pressure jet nozzle, a nozzle having a configuration in which an intake hole of a flow drawing device 121a, 121b, 121c described later is closed. In addition, the structure of an absorption liquid ejection part is not restricted to these, What is necessary is just to have a mechanism in which the absorption liquid 150 is atomized.

  As described above, a reflux path for refluxing the absorption liquid 150 is formed in the order of the absorption tower 100, the absorption liquid line 130, the regeneration tower 110, the absorption liquid line 131, and the absorption tower 100.

  The liquid feed pumps 160 and 161 operate based on a signal from the control unit 140, and adjust the flow rate of the absorbent 150 flowing through the absorbent liquid lines 130 and 131, and the like.

  Next, a recovery path for depressurizing the regeneration tower 110 and recovering the carbon dioxide and water vapor in the regeneration tower 110 to the decompression device 120 will be described.

  A carbon dioxide outlet 113 is provided in the upper part of the regeneration tower 110, and a carbon dioxide outlet 113 that guides carbon dioxide, water vapor, etc. to the flow-out devices 121a, 121b, 121c,. One end of 132 is connected. On the other hand, the other end of the carbon dioxide derivation line 132 is branched into a plurality and connected to the intake holes of the respective flow drawing devices 121a, 121b, 121c.

  One end of a liquid circulation line 133 provided with a liquid feed pump 162 is connected to the lower part of the decompression device 120. On the other hand, the other end of the liquid circulation line 133 is branched into a plurality, and is connected to the liquid introduction holes of the respective flow drawing devices 121a, 121b, 121c,.

  Further, one end of a liquid outlet line 134 provided with a liquid feed pump 163 is connected to the lower side surface of the decompression device 120. The other end of the liquid outlet line 134 is connected to the absorbing liquid line 131 on the downstream side of the cooler 170 interposed in the absorbing liquid line 131. Furthermore, a carbon dioxide recovery port 122 for taking out carbon dioxide to the outside is provided at the upper part of the decompression device 120.

  Here, the flow-drawing devices 121a, 121b, and 121c will be described with reference to FIG.

  FIG. 2 is a cross-sectional view showing an example of the configuration of the flow-drawing devices 121a, 121b, and 121c. As shown in FIG. 2, the flow-drawing devices 121 a, 121 b, and 121 c are mainly configured from a liquid flow path 180 through which the liquid 123 flows and a gas flow path 181 that guides the gas drawn into the liquid flow path 180. ing. The liquid flow path 180 has a structure in which the cross-sectional area is gradually decreased in the direction in which the liquid flows to form the nozzle portion 180a, and the cross-sectional area is gradually increased on the downstream side. The gas channel 181 is configured to communicate with the liquid channel 180 immediately downstream of the nozzle portion 180 a of the liquid channel 180.

  Since these flow-out devices 121a, 121b, 121c... Are interposed in the liquid circulation line 133, the liquid 123 circulated by the liquid circulation line 133 passes through the liquid introduction holes 182 into the flow-through devices 121a, 121b, 121c. Flows into the liquid flow path 180. The liquid 123 passing through the nozzle portion 180a of the liquid flow path 180 becomes a jet flow, and the gas A is flowed to the jet flow from the intake hole 183 through the gas flow path 181 by the flow-drawing action of the jet flow. The flowd gas A is discharged from the liquid discharge hole 184 together with the liquid 123 and guided into the decompression device 120. Moreover, in this flow-out apparatus 121a, 121b, 121c ..., in order to flow the gas A in the regeneration tower 110, the inside of the regeneration tower 110 is decompressed. Here, a configuration may be provided in which the liquid 123 flowing through the liquid flow path 180 is swung on the upstream side of the nozzle portion 180 a of the liquid flow path 180. In addition, the structure of the flow-drawing apparatus 121a, 121b, 121c ... is not restricted to an above-described structure, What is necessary is just to be able to exhibit the above-mentioned effect.

  Specifically, an aspirator (water flow pump) or the like is provided as the apparatus having the configuration of the above-described flow-drawing devices 121a, 121b, 121c. Here, the number of the flow-drawing devices 121a, 121b, 121c... Installed in the decompression device 120 is not particularly limited, and is set as appropriate according to the application and operating conditions. The decompression device 120 provided with the flow-drawing devices 121a, 121b, 121c,... Can reduce the pressure in the regeneration tower 110 to 20 to 80 kPa with absolute pressure.

  As described above, a recovery path for reducing the pressure in the regeneration tower 110 and recovering the carbon dioxide and water vapor in the regeneration tower 110 to the decompression device 120 is formed.

  The absorbent 150 used in the first embodiment is prepared by dissolving 10 to 28 g of sodium carbonate per 100 g of water and adjusting the weight concentration to 9 to 22%.

  The temperature of the absorbent 150 in the absorption tower 100 is set to 40 to 75 ° C. Further, the temperature of the absorbent 150 in the regeneration tower 110 is set to 60 to 90 ° C.

  Here, the temperature of the absorption liquid 150 in the absorption tower 100 was set in the range of 40 to 75 ° C., when the absorption liquid 150 mainly composed of sodium carbonate was less than 40 ° C. This is because carbon absorption is slow, and when it exceeds 75 ° C., carbon dioxide absorbed in the absorption liquid 150 starts to be dissipated in the absorption tower 100.

  In addition, the temperature of the absorbing liquid 150 in the regeneration tower 110 is set in the range of 60 to 90 ° C., when the absorbing liquid 150 mainly containing sodium carbonate is less than 60 ° C., the release of carbon dioxide is slow. This is because when the temperature exceeds 90 ° C., a large amount of water disappears from the absorbing liquid 150.

  Further, the liquid 123 circulated through the liquid circulation line 133 is warm water having a temperature substantially equal to the temperature of the absorbing liquid 150 in the absorption tower 100 and a temperature of 40 to 75 ° C. The temperature of the hot water is set to 40 to 75 ° C. When the temperature is lower than 40 ° C., the steam recovered in the decompression device 120 is cooled to lose heat energy, and when the temperature is higher than 75 ° C. This is because the steam recovered by the decompression device 120 is heated to consume heat energy.

  Further, the liquid 123 is not limited to hot water, and for example, hydraulic oil such as mineral oil or phosphate steal may be used. These hydraulic oils have a boiling point higher than that of water, and can be stably used even in a state where the temperature is high in the above-described temperature range. When hydraulic oil is used as the liquid 123, the hot water formed by condensation of water vapor from the regeneration tower 110 and the hydraulic oil are mixed in the decompression device 120. In this case, for example, when the specific gravity of the hydraulic oil is smaller than that of hot water, the upper layer is a layer of hydraulic oil that is the liquid 123, and the lower layer is a layer of hot water in which water vapor is condensed and stored. Note that the hydraulic oil used here does not dissolve in warm water.

  In this case, one end of the liquid lead-out line 134 that discharges the hot water from the decompression device 120 is connected to a lower portion of the decompression device 120, that is, a position where the hot water can be discharged from the hot water layer. Further, one end of the liquid circulation line 133 for circulating the working oil to the decompression device 120 through the flow-out devices 121a, 121b, 121c,... Corresponds to the region where the working oil layer is formed. That is, it is connected to a position where the hydraulic oil can be discharged from the hydraulic oil layer.

  When the specific gravity of the hydraulic oil is larger than that of hot water, the upper layer is a layer of warm water in which water vapor is condensed and stored, and the lower layer is a layer of hydraulic oil that is the liquid 123. In this case, the hydraulic oil ejected from the upper part of the decompression device 120 through the flow-drawing devices 121a, 121b, 121c... Along with the water vapor passes through the upper layer of hot water and reaches the lower layer. Therefore, for example, when the upper layer warm water is discharged through the liquid lead-out line 134, the working oil is mixed in the warm water. Therefore, it is preferable to use a working oil having a specific gravity smaller than that of the warm water. .

  Further, as the liquid 123, for example, diethanolamine (DEA), piperazine, or the like may be used. These liquids have a boiling point higher than that of water, and can be stably used even in a state where the temperature is high in the above temperature range. Further, these liquids 123 are water-soluble, and are dissolved in warm water by the decompression device 120, and the warm water is led to the liquid lead-out line 134, for example, so that the warm water is dissolved in the absorption liquid 150 and carbon dioxide is absorbed. Promote.

  Next, the operation of the carbon dioxide recovery system 10 will be described.

  Exhaust gas 103 discharged from a boiler of a thermal power plant or a municipal waste incineration plant is supplied into the absorption tower 100 by a gas blower 105. When the exhaust gas 103 is supplied into the absorption tower 100, the absorption liquid 150 is ejected from the absorption liquid ejection part 106 at the top of the absorption tower 100 through the absorption liquid line 131. In the absorption tower 100, the absorption liquid 150 and the exhaust gas 103 are in gas-liquid contact, and the absorption liquid 150 absorbs carbon dioxide contained in the exhaust gas 103. Further, the remaining exhaust gas containing nitrogen and carbon dioxide that has not been absorbed is released into the atmosphere from the exhaust port 108 of the absorption tower 100.

  The absorption liquid 150 that has absorbed carbon dioxide is introduced into the regeneration tower 110 from the regeneration absorption liquid inlet 111 of the regeneration tower 110 via the absorption liquid line 130 by the liquid feed pump 160. The inside of the regeneration tower 110 is in a reduced pressure state of 20 to 80 kPa in absolute pressure, and the absorbing liquid 150 releases the absorbed carbon dioxide. At this time, a part of the absorbent 150 stored at the bottom of the regeneration tower 110 is heated by the heater 171 to generate water vapor. The water vapor flows from the lower part to the upper part of the regeneration tower 110 and comes into gas-liquid contact with the absorbing liquid 150 from the upper part. By this contact, the carbon dioxide absorbed in the absorbing liquid 150 is released into the water vapor, and the absorbing liquid 150 is regenerated. Note that carbon dioxide is released from the absorption liquid 150 by contact with water vapor. In addition to this, carbon dioxide is also released from the absorption liquid 150 when the inside of the regeneration tower 110 is depressurized. A part of the absorption liquid 150 stored at the bottom of 110 generates water vapor.

  Further, the regenerated absorption liquid 150 stored at the bottom of the regeneration tower 110 is transferred from the absorption liquid inlet for absorption 100 to the absorption tower 100 via the absorption liquid line 131 by the liquid feed pump 161. Then, the carbon dioxide absorption process described above is performed again. In addition, when the temperature of the absorption liquid 150 flowing through the absorption liquid line 131 is high, the absorption liquid 150 is cooled by the cooler 170 interposed in the absorption liquid line 131. Further, the flow rate of the refrigerant in the cooler 170 is adjusted based on a signal from the control unit 140, for example.

  On the other hand, the carbon dioxide released into the regeneration tower 110 and the water vapor generated in the regeneration tower 110 are caused to flow by the liquid 123 flowing through the flow apparatus 121a, 121b, 121c,. It is led to the intake holes 183 of 121c. And it is guide | induced in the decompression device 120 with the liquid 123 which flows through the flow-drawing apparatus 121a, 121b, 121c .... Since carbon dioxide and water vapor are drawn by the flow-drawing devices 121a, 121b, 121c, and guided into the pressure-reducing device 120, the inside of the regeneration tower 110 is depressurized and can maintain a predetermined pressure-reduced state. . In addition to carbon dioxide and water vapor, for example, water droplets formed by condensation of water vapor in the regeneration tower 110 may be included in the regeneration tower 110.

  Moreover, since the inside of the decompression device 120 is atmospheric pressure, the water vapor introduced into the decompression device 120 is condensed into water. The condensation heat released during the condensation is given to water, which becomes warm water and is stored in the decompression device 120. In addition, since the water vapor is condensed in this way, high-concentration carbon dioxide is recovered through the carbon dioxide recovery port 122.

  As described above, in the carbon dioxide recovery system 10 of the first embodiment, since the pressure in the regeneration tower 110 can be reduced by the flow-out devices 121a, 121b, 121c,..., Regeneration using a vacuum pump or the like. Compared to the case where the pressure in the tower 110 is reduced, the energy required for the pressure reduction in the regeneration tower 110 can be greatly reduced. Moreover, also when performing a heat insulation process, the flow-drawing apparatus 121a, 121b, 121c ... is easier compared with a vacuum pump etc., Furthermore, dissipation of a thermal energy can be suppressed efficiently.

  Moreover, since the inside of the decompression device 120 is atmospheric pressure, most of the water vapor is condensed and recovered as hot water, so that carbon dioxide and water vapor can be separated, and high-concentration carbon dioxide is recovered. be able to. Furthermore, by using the heat of condensation released when water vapor condenses to form hot water, it is possible to effectively use thermal energy and promote energy saving as a system.

  Further, the absorption liquid 150 releases moisture as water vapor in the regeneration tower 110 to increase the concentration of the solute, but the hot water in the decompression device 120 is removed from the absorption liquid line 131, via the liquid lead-out line 134. Or since it can supply to the bottom part of the regeneration tower 110, the raise of the density | concentration of the solute in the absorption liquid 150 can be suppressed, and the absorption liquid 150 of predetermined concentration can be circulated. Moreover, since the temperature of the hot water in the decompression device 120 and the temperature of the absorption liquid 150 in the absorption tower 100 or the regeneration tower 110 are set to be approximately equal, a part of the warm water is supplied from the decompression device 120 to the absorption liquid line 131. Or, when supplying to the regeneration tower 110, heat energy such as heating is not required. Thereby, energy saving as a system can be promoted.

  Furthermore, since the carbon dioxide recovery system 10 can recover a large amount of carbon dioxide emitted from thermal power plants and municipal waste incineration plants without using excessive energy, it contributes to the prevention of global warming. Can do.

(Second Embodiment)
The carbon dioxide recovery system according to the second embodiment of the present invention uses an aqueous potassium carbonate solution as an absorbent in the carbon dioxide recovery system 10 according to the first embodiment described above. Accordingly, the basic configuration and operation of the carbon dioxide recovery system of the second embodiment are the same as those of the carbon dioxide recovery system 10 of the first embodiment, and therefore the second embodiment will be described with reference to FIG. The carbon dioxide recovery system will be described, and the description overlapping with the description in the carbon dioxide recovery system 10 of the first embodiment will be omitted.

  The absorption liquid used in the carbon dioxide recovery system of the second embodiment is prepared by dissolving 10 to 43 g of potassium carbonate per 100 g of water and adjusting the weight concentration to 9 to 30%. The temperature of the absorbent 150 in the absorption tower 100 is set to about 40 to 75 ° C. The temperature of the absorbent 150 in the regeneration tower 110 is set to about 70 to 95 ° C.

  Here, the temperature of the absorption liquid 150 in the absorption tower 100 was set to 40 to 75 ° C., when the temperature of the absorption liquid 150 containing potassium carbonate as a main solute is lower than 40 ° C., carbon dioxide to the absorption liquid 150. This is because a large amount of moisture disappears from the absorbing liquid 150 when the absorption of water is delayed and the temperature exceeds 75 ° C. In addition, the temperature of the absorbent 150 in the regeneration tower 110 is set to 70 to 95 ° C. When the temperature of the absorbent 150 having potassium carbonate as a main solute is lower than 70 ° C., the release of carbon dioxide is delayed. This is because when the temperature exceeds 95 ° C., a large amount of water vapor is generated from the absorbing liquid 150.

  For example, mineral oil-based or phosphate ester-based hydraulic oil is circulated in the flow-out devices 121a, 121b, 121c,.

  The liquid 123 circulated through the liquid circulation line 133 is warm water having a temperature substantially equal to the temperature of the absorbing liquid 150 in the regeneration tower 110 and a temperature of 70 to 95 ° C. The temperature of the hot water is set to 70 to 95 ° C. When the temperature is lower than 70 ° C., the steam recovered in the decompression device 120 is cooled to lose heat energy, and when the temperature is higher than 95 ° C. This is because the steam recovered by the decompression device 120 is heated to consume heat energy. Note that the hydraulic oil used here does not dissolve in warm water.

  Moreover, since these hydraulic fluids have a smaller specific gravity than the warm water, the upper layer is a layer of hydraulic fluid that is the liquid 123, and the lower layer is a warm water layer in which water vapor is condensed and stored. Therefore, as described above, one end of the liquid lead-out line 134 that discharges hot water from the decompression device 120 is connected to a lower portion of the decompression device 120, that is, a position where warm water can be discharged from the hot water layer. Further, one end of the liquid circulation line 133 for circulating the working oil to the decompression device 120 through the flow-out devices 121a, 121b, 121c,... Corresponds to the region where the working oil layer is formed. That is, it is connected to a position where the hydraulic oil can be discharged from the hydraulic oil layer.

  Here, the other end of the liquid outlet line 134 is connected to communicate with the bottom of the regeneration tower 110. And since the warm water supplied from the liquid derivation line 134 is 70-95 degreeC warm water, since the temperature of the absorption liquid 150 in the regeneration tower 110 is raised to 70-90 degreeC, the heat energy of the heater 171 is increased. Supply can be reduced.

  In the carbon dioxide recovery system of the second embodiment described above, as in the carbon dioxide recovery system of the first embodiment, the pressure in the regeneration tower 110 is reduced by the flow-out devices 121a, 121b, 121c. Therefore, compared with the case where the pressure in the regeneration tower 110 is reduced using a vacuum pump or the like, the energy required for the pressure reduction in the regeneration tower 110 can be greatly reduced. Moreover, also when performing a heat insulation process, the flow-drawing apparatus 121a, 121b, 121c ... is easier compared with a vacuum pump etc., Furthermore, dissipation of a thermal energy can be suppressed efficiently.

  Moreover, since the inside of the decompression device 120 is atmospheric pressure, most of the water vapor is condensed and recovered as hot water, so that carbon dioxide and water vapor can be separated, and high-concentration carbon dioxide is recovered. be able to. Furthermore, by using the heat of condensation released when water vapor condenses to form hot water, it is possible to effectively use thermal energy and promote energy saving as a system.

  Further, the absorption liquid 150 releases moisture as water vapor in the regeneration tower 110 to increase the concentration of the solute, but the hot water in the decompression device 120 is converted into the bottom of the regeneration tower 110 via the liquid lead-out line 134. Therefore, the increase in the concentration of the solute in the absorption liquid 150 can be suppressed, and the absorption liquid 150 having a predetermined concentration can be circulated.

  Further, even when the temperature of the absorbing liquid 150 in the regeneration tower 110 is in the range of 70 to 95 ° C., the saturation vapor pressure of the hydraulic oil in the same temperature range is very low as compared with the saturated vapor pressure of hot water. A sufficient decompression capability can be ensured without hindering the draw action in 121a, 121b, 121c.

  Furthermore, since the carbon dioxide recovery system 10 can recover a large amount of carbon dioxide emitted from thermal power plants and municipal waste incineration plants without using excessive energy, it contributes to the prevention of global warming. Can do.

  In the carbon dioxide recovery system of the first and second embodiments described above, an example in which the carbon dioxide recovery system of the present invention is adopted mainly in a thermal power plant equipped with a boiler, a municipal waste incinerator, or the like is shown. However, the use of the carbon dioxide recovery system of the present invention is not limited to these. For example, as described above, it can be employed in, for example, a natural gas mine, and can also be employed in a ship power system.

The schematic diagram which shows the carbon dioxide collection system of embodiment of this invention. Sectional drawing which shows an example of a structure of a casting apparatus. Schematic diagram showing a conventional carbon dioxide recovery system.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Carbon dioxide collection system, 100 ... Absorption tower, 103 ... Exhaust gas, 105 ... Gas blower, 110 ... Regeneration tower, 120 ... Decompression device, 121a, 121b, 121c ... Flow-out device, 122 ... Carbon dioxide collection port, 130, 131 ... Absorbing liquid line, 132 ... Carbon dioxide outlet line, 133 ... Liquid circulation line, 134 ... Liquid outlet line, 150 ... Absorbing liquid, 140 ... Controller.

Claims (10)

A gas introduction port, an absorption liquid introduction port for absorption, a remaining gas discharge port and an absorption liquid discharge port are provided, and the gas introduced from the gas introduction port and the absorption liquid introduced from the absorption liquid introduction port for absorption are gas-liquid. An absorption device that makes the absorption liquid absorb carbon dioxide in the gas,
A regeneration device comprising a regeneration absorbent inlet, a regeneration absorbent outlet, and a carbon dioxide outlet, and regenerating the absorbent by releasing carbon dioxide from the absorbent that has absorbed the carbon dioxide;
A first absorbing liquid line for guiding the absorbing liquid discharged from the absorbing liquid discharge port of the absorbing apparatus to the regenerating absorbing liquid inlet of the regenerating apparatus;
A second absorption liquid line for guiding the absorption liquid discharged from the regeneration absorption liquid discharge port of the regeneration apparatus to the absorption liquid introduction port for absorption of the absorption apparatus;
A liquid circulation line that circulates a liquid at a predetermined temperature; and a flow-out device that draws a gas in the regenerator using a flow of the liquid that circulates in the liquid circulation line. A carbon dioxide recovery system comprising: a decompression device that recovers gas.   The carbon dioxide recovery system according to claim 1, further comprising a liquid lead-out line that guides the liquid at a predetermined temperature in the decompression device to the first absorption liquid line or the regeneration device.   The carbon dioxide recovery system according to claim 1 or 2, wherein the average temperature of the liquid circulated in the liquid circulation line of the decompression device is substantially equal to the average temperature of the absorption liquid in the absorption device.   The carbon dioxide recovery system according to claim 1 or 2, wherein the average temperature of the liquid circulated in the liquid circulation line of the decompression device is substantially equal to the average temperature of the absorbing liquid in the regenerator.   The carbon dioxide recovery system according to any one of claims 1 to 4, wherein a main solute of the absorption liquid is sodium carbonate or potassium carbonate.   The carbon dioxide recovery system according to any one of claims 1 to 5, wherein the gas is natural gas containing boiler, exhaust gas from an incinerator, or mined carbon dioxide.   The carbon dioxide recovery system according to any one of claims 1 to 6, wherein the liquid circulating in the liquid circulation line is water or oil having heat resistance.   The carbon dioxide recovery system according to any one of claims 1 to 7, wherein the flow-drawing device includes an aspirator. An absorption step of guiding the gas and the absorption liquid to an absorption device, bringing the gas and the absorption liquid into gas-liquid contact, and allowing the absorption liquid to absorb carbon dioxide in the gas;
A regenerating step of regenerating the absorbing solution by guiding the absorbing solution that has absorbed carbon dioxide in the absorbing step to a regenerating device, releasing the carbon dioxide from the absorbing solution;
A depressurizing and recovering step of circulating a liquid at a predetermined temperature, drawing a gas in the regenerator using the flow of the circulating liquid, depressurizing the regenerator, and collecting the gas. A carbon dioxide recovery method characterized by the above.   The carbon dioxide recovery method according to claim 9, further comprising a liquid derivation step for guiding a liquid at a predetermined temperature in the decompression device to the absorption device or the regeneration device.

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