JP6225572B2 - Carbon dioxide recovery method and recovery apparatus - Google Patents

Description

  The present invention relates to a carbon dioxide recovery method and recovery device for separating and recovering carbon dioxide from a gas containing carbon dioxide such as combustion gas and reducing clean gas to the atmosphere.

  Facilities such as thermal power plants, steelworks, and boilers use large amounts of fuel such as coal, heavy oil, and super heavy oil. Sulfur oxides, nitrogen oxides, and carbon dioxide emitted by the combustion of fuel are There is a need for quantitative and concentration restrictions on emissions from the perspective of air pollution prevention and global environmental protection. In recent years, carbon dioxide has been seen as a major cause of global warming, and movements to suppress emissions have become active worldwide. For this reason, in order to enable the recovery and storage of carbon dioxide from combustion exhaust gases and process exhaust gases without releasing them into the atmosphere, various researches have been vigorously advanced. As a carbon dioxide recovery method, for example, PSA ( Known are pressure swinging), membrane separation and concentration, and chemical absorption using reaction absorption by basic compounds.

  In the chemical absorption method, mainly alkanolamine-based basic compounds are used as the absorbent. In the treatment process, an aqueous liquid containing the absorbent is generally used as the absorbent, and carbon dioxide contained in the gas is absorbed into the absorbent. The absorbing solution is circulated so as to alternately repeat the absorbing step to be performed and the regeneration step of regenerating the absorbing solution by releasing the absorbed carbon dioxide from the absorbing solution (see, for example, Patent Document 1 below). In the regeneration process, heating to release carbon dioxide is necessary, and in order to reduce the operating cost of carbon dioxide recovery, the recovery device configuration is devised to reduce the energy required for heating during regeneration. Is done.

  In the carbon dioxide recovery device, a cooler is provided for adjusting the exhaust gas introduced into the absorption tower to an appropriate temperature so that the absorption of carbon dioxide by the absorbent proceeds well at the appropriate temperature in the absorption tower. . For example, as described in Patent Document 1, an exhaust gas cooling device is provided in the front stage of the absorption tower, and cooling is performed so that the inlet temperature of the exhaust gas introduced into the absorption tower is about 40 ° C. Since the temperature of the exhaust gas introduced into the absorption tower rises due to the reaction heat that the absorbing solution absorbs carbon dioxide, if the gas from which carbon dioxide has been removed is discharged directly from the absorption tower, a large amount of water vapor is released outside the tower. As a result, moisture is taken away from the absorption liquid in the tower. In order to prevent this, it is necessary to cool the gas discharged from the absorption tower to condense the water vapor, and in Patent Document 1, cooling is performed so that the gas outlet temperature is about 40 ° C. .

  The cooler used in the carbon dioxide recovery device is not limited to the one described above, but is discharged from a cooler for adjusting the temperature of the absorption liquid refluxed from the regeneration tower to the absorption tower, or from the regeneration tower. It also has a cooler to cool the hot carbon dioxide gas.

JP2011-526A

  The cooler used in the carbon dioxide recovery device is generally cooled by heat exchange using cooling water as a refrigerant. Although the cooling temperature calculated | required by a cooler changes with installation locations, it can adjust to different cooling temperature for every cooler using the same cooling water by adjusting cooling efficiency with the flow volume of cooling water. The cooling water heated in each cooler is collected in a radiator, lowered to the original temperature, and reused. Usually, a vaporized radiator is used.

  Since the vaporization radiator dissipates and cools by evaporation of water, the cooling water decreases according to the amount of heat radiation. Accordingly, there is no problem in an area where water resources are abundant, but it is desirable that the amount of cooling water vaporized can be reduced in areas where water resources are scarce, that is, a reduction in heat dissipation is desired. In order to realize this, it is necessary to set the cooling temperature of the cooler used in the carbon dioxide recovery device as high as possible.

  An object of the present invention is to solve the above-mentioned problems and to reduce the amount of vaporization in a vaporization radiator of cooling water, which is a refrigerant of a cooler used in carbon dioxide recovery, and in a region where water resources are scarce. It is an object of the present invention to provide a carbon dioxide recovery method and a recovery apparatus that can easily perform the recovery process in comparison with the related art.

  In order to solve the above-mentioned problems, the present inventors have conducted extensive research. As a result, even if the outlet temperature at which the gas from which carbon dioxide has been removed is discharged from the absorption tower is set higher than before, water vapor is released outside the apparatus. Thus, the present invention has been completed by finding that it is possible to reduce the heat radiation amount and the vaporized water amount of the cooling water in the vaporizer.

According to one aspect of the present invention, a carbon dioxide recovery device includes a pretreatment tower that cools a gas saturated with water vapor to an appropriate temperature in advance, and a gas cooled in the pretreatment tower is brought into contact with an absorption liquid. An absorption tower having a gas-liquid contact part that absorbs carbon dioxide contained in the gas into the absorption liquid, a cooling part that cools the treated gas that has passed through the gas-liquid contact part, and absorbs carbon dioxide in the absorption tower. A regenerated tower that regenerates the absorbent by heating the absorbed liquid to release carbon dioxide, condensed water generated from the gas by cooling in the pretreatment tower, and after the treatment by cooling in the cooling section of the absorption tower A water supply system that supplies the absorption liquid with an amount of water corresponding to the total amount of condensed water generated from the gas, and the temperature of the post-treatment gas cooled by the cooling section and the pretreatment tower cooled by the pretreatment tower. The difference from the gas temperature before And summarized in that the cooling unit is set to be within.

Moreover, according to one aspect of the present invention, a method for recovering carbon dioxide includes a pretreatment step in which a gas saturated with water vapor is cooled to an appropriate temperature in advance, and the gas cooled in the pretreatment step is brought into contact with an absorbing liquid. An absorption step of absorbing carbon dioxide contained in the gas into the absorption liquid, a cooling step of cooling the treated gas after the absorption step, and heating the absorption liquid that has absorbed the carbon dioxide in the absorption step. An amount corresponding to a total amount of condensed water generated from the gas by cooling in the pretreatment step, and condensed water generated from the post-treatment gas in the cooling step; A water supply step for supplying water to the absorbing solution, and a difference between the temperature of the treated gas cooled in the cooling step and the temperature of the gas before cooled in the pretreatment step is within 3 ° C The cooling work to be And summarized in that to adjust.

  According to the present invention, it is possible to reduce the amount of heat required for the cooler used in the process of recovering carbon dioxide contained in the gas, so that the cooling water as the coolant of the cooler is maintained at a predetermined temperature. It is possible to reduce the amount of vaporized water in the vaporizing radiator to perform, and in an area where water resources are scarce, there is a carbon dioxide recovery method and recovery device that are advantageous in promoting the implementation of carbon dioxide recovery processing such as combustion exhaust gas. Provided and useful in environmental protection. It is economically advantageous because it can be carried out easily using general equipment without requiring special equipment or expensive equipment.

1 is a schematic configuration diagram showing a carbon dioxide recovery apparatus according to a first embodiment of the present invention. The schematic block diagram which shows the collection | recovery apparatus of the carbon dioxide which concerns on the 2nd Embodiment of this invention. The schematic block diagram which shows the collection | recovery apparatus of the carbon dioxide which concerns on the 3rd Embodiment of this invention. The schematic block diagram which shows the collection | recovery apparatus of the carbon dioxide which concerns on the 4th Embodiment of this invention.

  The carbon dioxide recovery process by the chemical absorption method consists of an absorption process in which carbon dioxide contained in exhaust gas is absorbed by a low-temperature absorption liquid, and a high-temperature regeneration process in which the absorbed carbon dioxide is released from the absorption liquid to regenerate the absorption liquid. In order to repeat these alternately, the absorption liquid is circulated between the absorption tower for performing the absorption process and the regeneration tower for performing the regeneration process. The temperature of the exhaust gas for recovering carbon dioxide by the recovery process is usually about 50 ° C. or higher, but it is preferable that the temperature in the absorption tower is low from the viewpoint of absorption efficiency into the absorption liquid. A pretreatment tower for cooling the temperature to a temperature suitable for the absorption treatment is provided, and the exhaust gas is cooled to about 40 ° C. or less and then introduced into the absorption tower. Further, since the absorbing solution generates heat due to reaction heat when absorbing carbon dioxide, the temperature of the gas passing through the absorption tower also rises. Therefore, when the gas after removing carbon dioxide is released from the absorption tower as it is, water vapor is released together with the gas, and the absorption liquid in the absorption tower is concentrated. In order to prevent this, before discharging the gas in the absorption tower to the outside of the tower, it is necessary to cool it to around 40 ° C., which is the same as the temperature at which the exhaust gas is introduced into the absorption tower. The amount of heat required for the cooling applied in is great. However, if the recovery device is configured so that the absorption liquid can be prevented from concentrating even if the temperature of the released gas is high, the amount of cooling heat in the cooler can be reduced, and the water used for cooling can be evaporated and dissipated. It is possible to reduce the amount of vaporized water when the temperature is lowered to the original temperature.

  In the present invention, the outlet temperature at the time of releasing the gas from the absorption tower is set to the temperature of the exhaust gas before being cooled in the pretreatment tower, that is, the initial temperature of the exhaust gas, and the amount of released water vapor increases as the outlet temperature increases. The apparatus is configured so that water corresponding to the increased amount of water can be replenished from the pretreatment tower to prevent the concentration of the absorbing solution. In other words, the management range of the water vapor contained in the gas is expanded from the absorption tower to the range including the pretreatment tower, and the amount of cold heat can be reduced by using the condensed water recovered in the pretreatment tower. The carbon dioxide recovery method and recovery apparatus of the present invention configured as described above will be described in detail below with reference to the drawings.

  FIG. 1 shows a first embodiment of a carbon dioxide recovery method and a recovery apparatus for carrying out the same according to the present invention. The recovery device 1 is configured to bring the gas G containing carbon dioxide into contact with the absorption liquid and to absorb the carbon dioxide in the absorption liquid and to heat the absorption liquid that has absorbed the carbon dioxide to absorb the carbon dioxide. And a regeneration tower 20 for regenerating the absorbent. Further, a pretreatment tower 30 having a function as a cooling tower for preliminarily cooling the gas G supplied to the absorption tower 10 and adjusting the gas G to an appropriate temperature suitable for carbon dioxide absorption is provided. It can also handle processing. There is no restriction | limiting in particular about the gas G supplied to the collection | recovery apparatus 1, Handling of various gas, such as combustion exhaust gas and process exhaust gas, is possible. The absorption tower 10, the regeneration tower 20 and the pretreatment tower 30 are each configured as a countercurrent gas-liquid contact device, and have gas-liquid contact portions 11, 21, 31 formed of a filler for increasing the contact area. Each is held inside. The fillers constituting the gas-liquid contact parts 11, 21, 31 are generally made of ferrous metal materials such as stainless steel and carbon steel, but are not particularly limited, and are durable and corrosion resistant at the processing temperature. A material having a property that can provide a desired contact area can be appropriately selected and used. As the absorbing liquid, an aqueous liquid containing a compound having an affinity for carbon dioxide such as alkanolamines as an absorbent is used. The absorption liquid is supplied above the gas-liquid contact part 11 of the absorption tower 10 and absorbs carbon dioxide in the gas G by gas-liquid contact with the gas G while passing through the gas-liquid contact part 11. The absorption liquid (rich liquid) A1 that has absorbed carbon dioxide is stored at the bottom of the absorption tower 10 and is supplied to the regeneration tower 20 by a pump 12 through a supply path 16 that connects the bottom of the absorption tower 10 and the top of the regeneration tower 20. . The absorption liquid (lean liquid) A2 regenerated in the regeneration tower 20 is refluxed by the pump 23 from the bottom of the regeneration tower 20 to the upper part of the gas-liquid contact portion 11 of the absorption tower 10 through the reflux path 17. That is, a circulation system that circulates the absorption liquid between the absorption tower and the regeneration tower by the supply path 16, the reflux path 17, and the pumps 12 and 23 is constructed.

  In order to constitute a cooling system for cooling the gas G passing through the gas-liquid contact part 31, the pretreatment tower 30 is connected with a pump 32 for transporting the cooling water W1, a water-cooled cooler 33, and these. A circulation path 34 is attached to the outside, and the cooling water W1 at the bottom of the pretreatment tower 30 is supplied to the cooler 33 through the circulation path 34 by driving the pump 32, and the cooling water W1 cooled by the cooler 33 is the pretreatment tower 30 It recirculates above the gas-liquid contact part 31 in 30. The gas G supplied from the lower part of the pretreatment tower 30 is cooled by the cooling water W1 supplied from the upper part while passing through the gas-liquid contact part 31, and then passes through the demister 35 for removing fine droplets. Then, the gas is supplied to the absorption tower 10 through the air supply pipe 18 connecting the top of the pretreatment tower 30 and the bottom of the absorption tower 10. The initial temperature T0 of the gas G subjected to the carbon dioxide recovery process is normally about 50 ° C., and is cooled to a temperature T1 of about 40 ° C. in the pretreatment tower 30, so that the gas G has a temperature T1 appropriate for the absorption process. The temperature rise in the absorption tower 10 caused by the temperature of the gas G introduced into the absorption tower 10 is prevented. The cooling water W <b> 1 whose temperature has increased due to contact with the gas G at the gas-liquid contact portion 31 flows down to the bottom of the pretreatment tower 30 and is supplied from the circulation path 34 to the cooler 33.

  The circulation path 34 for circulating the cooling water W1 is provided with a branch path 36 for diverting the excess amount of the cooling water W1 when the circulating cooling water W1 exceeds a predetermined amount, and the pretreatment tower 30 and the cooler 33 are provided. The amount of the cooling water W1 that circulates is maintained constant. Therefore, when the water vapor pressure of the gas G decreases below the saturated water vapor pressure at the temperature T1 due to the cooling at the gas-liquid contact portion 31, and condensed water is generated, this is added to the cooling water W1 and becomes an integral unit, and the cooling water W1 increases. Therefore, the increased amount ΔW1 (that corresponds to condensed water) of the cooling water W1 is diverted from the circulation path 34 through the branch path 36, and finally added to the absorbing liquid. In this regard, in the embodiment of FIG. 1, the increased amount ΔW1 of the cooling water W1 is supplied to the upper part of the absorption tower 10 before being added to the absorption liquid and used as cooling water (details will be described later). However, it is also possible to change the connection destination of the branch path 36 to the supply path 16 or the like so as to be added directly to the absorbing liquid. The cooling water W1 from which the increased amount ΔW1 has been separated by the branch path 36 is cooled by the cooler 33 and supplied to the gas-liquid contact portion 31. If a temperature sensor is provided in the air supply pipe 18 and the drive of the pump 32 is controlled in accordance with the detected temperature of the gas G introduced into the bottom of the absorption tower 10, the fluctuation of the initial temperature T0 of the gas G is caused. When the temperature T1 rises, the temperature T1 of the gas G can be lowered and maintained properly by increasing the heat exchange rate by increasing the circulation flow rate of the cooling water W1.

  The gas G containing carbon dioxide that has passed through the pretreatment tower 30 is supplied from the lower part of the absorption tower 10. While the gas G and the absorption liquid pass counter-current through the gas-liquid contact portion 11, carbon dioxide in the gas G is absorbed by the absorption liquid by the gas-liquid contact. In the gas-liquid contact portion 11, the absorption liquid generates heat due to absorption of carbon dioxide and the liquid temperature rises. Therefore, moisture is evaporated from the absorption liquid, the absorption liquid is concentrated, and the gas G ′ from which carbon dioxide has been removed is also water vapor. The amount increases and the temperature rises. For this reason, the cooling part 13 for condensing and recovering water vapor or the like contained in the gas G ′ is formed above the gas-liquid contact part 11 using a filler, and carbon dioxide is removed by the gas-liquid contact part 11. The treated gas G ′ is cooled while passing through the cooling unit 13 to reduce the amount of water vapor, and then discharged from the top of the absorption tower 10. The cooling mode in the cooling unit 13 is configured to be the same as that of the gas-liquid contact unit 31 of the pretreatment tower 30. Specifically, in order to configure the cooling system, a pump 15 for supplying the cooling water W2 to the cooling unit 13, a water-cooled cooler 14 for cooling the cooling water W2, and a circulation connecting them. A passage 37 is attached to the outside of the absorption tower 10, and a partition member 19 is provided below the cooling unit 13. The partition member 19 has a horizontal annular plate, a tubular wall standing on the periphery of the center hole thereof, and an umbrella portion covering the upper end hole of the tubular wall, and the inner wall of the absorption tower 10 and the partition member 19 A liquid pool is formed on the horizontal annular plate between the tubular wall and partitions between the gas-liquid contact part 11 and the cooling part 13. The partition member 19 is connected to the pump 15 and the cooler 14 by a circulation path 37, and the cooling water W <b> 2 circulates between the cooling unit 13 and the cooler 14 through the partition member 19 by driving the pump 15. The cooling water W <b> 2 flowing down the cooling unit 13 falls on the partition member 19 and is stored in the liquid pool, is sent to the cooler 14 through the circulation path 37, is cooled, and is supplied to the cooling unit 13 again. Similarly to the circulation path 34 of the pretreatment tower 30, the circulation path 37 is configured such that the amount of the cooling water W2 circulating through the cooling unit 13 and the cooler 14 is kept constant, and the increased cooling water W2 The excess is diverted by a branch path 38 that branches from the circulation path 37. When the treated gas G ′ that has reached the cooling unit 13 from the gas-liquid contact unit 11 through the tubular wall of the partition member 19 is cooled, condensed water (which may include an absorbent) is generated and the partition member together with the cooling water W2. It falls on 19 and becomes integrated with the cooling water W2 in the liquid pool, and the cooling water W2 increases. Further, since the downstream end of the branch path 36 is connected to the circulation path 37, the increased amount ΔW 1 of the cooling water W 1 diverted from the circulation path 34 of the pretreatment tower 30 is also added to the cooling water W 2 of the circulation path 37. Therefore, the condensed water condensed in the gas-liquid contact part 31 and the cooling part 13 of the pretreatment tower 30 is used as cooling water. Since the amount of the cooling water W2 that circulates between the cooling unit 13 and the cooler 14 in the circulation path 37 is kept constant, the amount of increase ΔW2 of the increased cooling water W2, that is, the cooling unit is cooled by cooling the processed gas G ′. The total amount of cooling water of the amount of condensed water generated in 13 and the amount of increase ΔW1 of the cooling water W1 supplied from the branch path 36 (corresponding to the condensed water in the gas-liquid contact portion 31) is the branch path 38. And is added to the absorption liquid A1 flowing through the supply path 16. This is substantially equivalent to the fact that the condensed water generated in the cooling unit 13 and the condensed water generated in the pretreatment tower 30 are added directly to the absorbing liquid A1 in the supply path 16. The cooling water W <b> 2 after the increase ΔW <b> 2 is separated by the branch path 38 is supplied to the cooler 14, cooled, and supplied to the cooling unit 13.

  The gas G at the temperature T1 supplied from the lower part of the absorption tower 10 goes up through the tower, passes through the gas-liquid contact section 11, undergoes carbon dioxide recovery processing, and then removes fine droplets as post-treatment gas G ′. The demister 39 and the tubular wall inner hole of the partition member 19 are cooled by the cooling unit 13 and discharged to the outside through the demister 40. In the present invention, the temperature T2 of the treated gas G ′ cooled by the cooling unit 13 is set to a temperature substantially equal to the initial temperature T0 that is the temperature before the gas G is cooled in the pretreatment tower 30 (practical). Is set within T0 ± 3 ° C., preferably within T0 ± 2 ° C.). As a result, the amount of water vapor contained in the gas G introduced into the pretreatment tower 30 is equal to the amount of water vapor contained in the post-treatment gas G ′ released from the absorption tower 10. Since the amount of water equal to the condensed water generated from the gases G and G ′ in the pretreatment tower 30 and the absorption tower 10 is replenished to the absorption liquid, the concentration of the absorption liquid A1 concentrated in the gas-liquid contact section 11 is the original. The concentration of the absorbing solution in the absorption tower 10 is eliminated. That is, even if the temperature at which the treated gas G ′ is released is increased, the introduction gas and the discharge gas have the same water vapor content, and the concentration of the absorbing solution is prevented. Therefore, it is possible to achieve a reduction in the amount of heat in the cooler 14 by setting the cooling temperature T2 in the cooling unit 13 higher than the gas inlet temperature (T1) of the absorption tower 10. Furthermore, since the outlet temperature T2 of the treated gas G ′, that is, the temperature cooled by the cooling unit 13, is higher than the temperature T1 of the gas G introduced from the pretreatment tower 30 to the absorption tower 10, the temperature of the pretreatment tower 30 The cooling water W1 can be used as a refrigerant of the cooling unit 13 (T1 <T2), and in the above configuration, water condensed in the pretreatment tower 30 (or an amount of water equivalent thereto) is cooled in the circulation path 37. For water (or an amount of water equal to the amount of water) that is indirectly added to the absorption liquid A1 of the supply path 16 through use as water and condensed in the cooling unit 13 of the absorption tower 10, the absorption liquid in the supply path 16 Added directly. In this manner, the amount of cold heat in the cooler 14 can be further reduced by passing the water diverted from the circulation path 34 through the circulation path 37 before being added to the absorbent.

  The absorption liquid A1 at the bottom of the absorption tower 10 is restored to its original concentration by the water added from the branch path 38 on the supply path 16 and is supplied to the upper part of the regeneration tower 20 and passes over the filler in the gas-liquid contact section 21. It flows down and is stored at the bottom. A reboiler is attached to the bottom of the regeneration tower 20. That is, a steam heater 22 provided outside the regeneration tower 20 for heating the absorption liquid and a circulation path 22 ′ for circulating the absorption liquid through the steam heater 22 are provided, and one of the absorption liquid A 2 at the bottom of the tower is provided. The part is divided into a steam heater 22 through a circulation path 22 ', heated by heat exchange with high-temperature steam, and then refluxed into the tower. Due to this heating, carbon dioxide is released from the absorption liquid at the bottom, and the filler in the gas-liquid contact portion 21 is also indirectly heated, and carbon dioxide is released from the absorption liquid by gas-liquid contact on the filler. Promoted.

  The absorption liquid (lean liquid) A2 regenerated by releasing carbon dioxide in the regeneration tower 20 is refluxed to the absorption tower 10 by the pump 23 through the reflux path 17. A heat exchanger 24 that performs heat exchange between the supply path 16 and the reflux path 17 is provided, and the absorbent A1 in the supply path 16 that is supplied from the absorption tower 10 to the regeneration tower 20 is refluxed from the regeneration tower 20. The absorbing liquid A2 is heated, and the absorbing liquid A2 is cooled on the contrary. Further, the absorption liquid A2 in the reflux path 17 is sufficiently cooled by the water-cooled cooler 25 to a temperature suitable for carbon dioxide absorption (about T1). Various types of heat exchangers such as spiral type, plate type, double pipe type, multiple cylinder type, multiple circular pipe type, spiral tube type, spiral plate type, tank coil type, tank jacket type, direct contact liquid type, etc. Any type may be used as the heat exchanger 24 in the present invention, but the plate type is superior in terms of simplification of the apparatus and ease of cleaning and disassembly.

  The gas containing carbon dioxide released by heating in the regeneration tower 20 is discharged as a recovered gas C from the top through the condensing part 26 at the top of the regeneration tower 20. The condensing unit 26 condenses the water vapor contained in the recovered gas C to suppress excessive release, and also suppresses the release of the absorbent. Outside the regeneration tower 20, a water-cooled cooler 27, a gas-liquid separator 28 and a pressure regulating valve 29 for cooling the recovered gas C are provided and discharged through a demister 41 at the top of the regeneration tower 20. The recovered gas C is sufficiently cooled by the cooler 27 through the exhaust pipe 42, and the contained water vapor is condensed as much as possible. Condensed water and the like are separated in the gas-liquid separator 28 and supplied from the flow path 44 onto the condensing unit 26 of the regeneration tower 20 by the pump 43 and used as cooling water. Carbon dioxide contained in the recovered gas C discharged from the exhaust pipe 42 can be fixed and reorganized in the ground by injecting it into the ground or an oil field, for example. The pressure regulating valve 29 provided on the gas discharge side of the gas-liquid separator 28 can be used for adjusting the pressure in the regeneration tower 20 and can be regenerated in a pressurized state. Good.

  A collection method implemented in the collection apparatus 1 of FIG. 1 will be described.

  When the gas G containing carbon dioxide such as combustion exhaust gas and process exhaust gas is supplied from the bottom in the pretreatment tower 30, the gas G is cooled in the gas-liquid contact part 31 as cooling water circulating in the circulation path 34 as a pretreatment step. The temperature is cooled from the initial temperature T0 to the temperature T1 by W1, and condensed water is generated from the gas G due to a decrease in the saturated water vapor pressure. An increase ΔW1 corresponding to the condensed water in the cooling water W1 increased by the condensed water is supplied from the branch path 36 to the circulation path 37 of the absorption tower 10. The temperature T1 is set in a range of about 30 to 40 ° C. by adjusting the water temperature of the cooling water W1 and the supply flow rate to the gas-liquid contact portion 31. The gas G cooled to the temperature T1 is introduced into the absorption tower 10. The water temperature of the cooling water W1 is adjusted by the cooling efficiency of the cooler 33 (that is, the flow rate of the cooling water (refrigerant)).

  When the gas G is supplied from the bottom and the absorption liquid is supplied from the top in the absorption tower 10, the gas G and the absorption liquid come into gas-liquid contact on the gas-liquid contact portion 11, and carbon dioxide is absorbed by the absorption liquid. Since carbon dioxide is well absorbed at low temperatures, it is preferable to control the temperature so that the liquid temperature of the absorbing liquid or the temperature of the absorption tower 10 (particularly the gas-liquid contact portion 11) is about 40 ° C. or lower. Since the absorbing liquid generates heat due to absorption of carbon dioxide, it is desirable to take into consideration the increase in liquid temperature caused by this, so that the liquid temperature does not exceed 60 ° C. An aqueous liquid containing a compound having affinity for carbon dioxide as an absorbent is used as the absorbent. Examples of the absorbent include alkanolamines and hindered amines having an alcoholic hydroxyl group. Specific examples of the alkanolamine include monoethanolamine, diethanolamine, triethanolamine, methyldiethanolamine, diisopropanolamine, diisopropanol. Examples of the hindered amine having an alcoholic hydroxyl group include 2-amino-2-methyl-1-propanol (AMP), 2- (ethylamino) ethanol (EAE), and 2- (methylamino). ) Ethanol (MAE) and the like can be exemplified. Usually, the use of monoethanolamine (MEA) is preferred, and a plurality of the above compounds may be used in combination. The absorbent concentration of the absorption liquid can be appropriately set according to the amount of carbon dioxide contained in the gas to be processed, the processing speed, etc. The concentration of about 10 to 50% by mass is applied. For example, for the treatment of the gas G having a carbon dioxide content of about 20%, an absorbing solution having a concentration of about 30% by mass is preferably used. The supply rates of the gas G and the absorbing liquid are appropriately set so that the absorption proceeds sufficiently according to the amount of carbon dioxide contained in the gas, the gas-liquid contact efficiency, and the like.

  The post-treatment gas G ′ from which carbon dioxide has been removed in the gas-liquid contact portion 11 increases in water vapor amount as the temperature rises due to reaction heat, but is cooled to the temperature T2 by the cooling water W2 while passing through the cooling portion 13. After the amount of water vapor is reduced, the water is discharged from the top of the absorption tower 10. Cooled by the cooling unit 13 so that the amount of water vapor contained in the gas G introduced into the pretreatment tower 30 and the amount of water vapor contained in the treated gas G ′ released from the absorption tower 10 are substantially equal. The temperature T2 of the treated gas G ′ is substantially equal to the initial temperature T0 that is the temperature before the gas G is cooled by the pretreatment tower 30 (practically within T0 ± 3 ° C., preferably T0 Set within ± 2 ℃. The setting of the temperature T2 can be adjusted by the water temperature of the cooling water W2 and the supply flow rate to the cooling unit 13. The condensed water generated in the cooling unit 13 is stored in the lower partition member 19 together with the cooling water W2, and circulates in the circulation path 37 from the partition member 19 via the cooler 14 by the pump 15. In the meantime, since the cooling water ΔW1 supplied from the pretreatment tower 30 through the branch path 36 is added, the increased amount ΔW2 of the increased cooling water W2 [that is, the condensation generated in the cooling unit 13 due to the cooling of the treated gas G ′. The total amount of water and the amount of cooling water ΔW1 (corresponding to condensed water in the gas-liquid contact portion 31) supplied from the branch path 36 is added to the circulating absorbent liquid A1 through the branch path 38. The In other words, the water vaporized from the absorption liquid in the gas-liquid contact portion 11 is supplemented with water added from the branch path 38, and a water supply step is performed in which the concentrated absorption liquid A1 is diluted to recover the original concentration. . Therefore, even if the outlet temperature of the treated gas G ′ is increased from T1 to T2, the reduced amount of condensed water in the cooling unit 13 due to this increase is compensated by the condensed water in the pretreatment tower 30.

  The absorbing liquid A1 that has absorbed carbon dioxide in the absorption tower 10 is supplied to the regeneration tower 20 through the supply path 16 by the driving force of the pump 12. Meanwhile, in the heat exchanger 24, the absorption liquid A1 is heat-exchanged with the absorption liquid A2 refluxed from the regeneration tower 20. The difference between the outlet temperature of the absorbing liquid A1 and the inlet temperature of the absorbing liquid A2 in the heat exchanger 24 can be configured to be about 10 ° C. or less. The absorbing liquid A1 is a temperature close to the heating temperature in the regeneration tower 20. The temperature is increased. The heating temperature of the absorbing liquid A2 in the regeneration tower 20 varies depending on the absorbing liquid composition used and the regeneration conditions, but is generally set to about 100 to 130 ° C. Based on this, the heat exchanger outlet of the absorbing liquid A1 in heat exchange The temperature can be raised to about 95-125 ° C.

  The absorbing liquid A1 supplied to the regeneration tower 20 at a high temperature releases carbon dioxide while flowing down the gas-liquid contact portion 21. The release of carbon dioxide is promoted by the gas-liquid contact on the filler of the gas-liquid contact portion 21, and the temperature rise and the release of carbon dioxide further progress by heating at the bottom of the regeneration tower 20. The absorbent A2 stored in the bottom is heated to the vicinity of the boiling point by partial circulation heating, and the boiling point of the absorbent depends on the composition (absorbent concentration) and the pressure in the regeneration tower 20. At this time, it is necessary to supply the latent heat of vaporization of water lost from the absorption liquid and the sensible heat of the absorption liquid.Suppressing the vaporization by pressurization increases the sensible heat due to the rise in boiling point. If the condition setting in which the inside of the regeneration tower 20 is pressurized to about 100 kPaG and the absorbing solution is heated to 120 to 130 ° C. is used, it is effective in terms of energy efficiency. The pressurization in the regeneration tower 20 can be adjusted by controlling the pressure regulating valve 29 provided at the outlet of the exhaust pipe 42.

  Since the temperature of the upper part of the regeneration tower 20 is close to the temperature of the absorption liquid A1 to be charged, the recovered gas that has passed through the condensing unit 26 is sufficiently cooled by the cooling water (refrigerant) in the cooler 27. Moisture and absorbent condensing from the recovered gas C are separated from the recovered gas C in the gas-liquid separator 28, and by supplying this to the condensing unit 26, the condensing unit 26 is cooled, and the absorption liquid in the regenerator 20 Suppresses increase in concentration and evaporation of absorbent.

  The absorbent A2 regenerated in the regeneration tower 20 is refluxed to the absorption tower 10 through the reflux path 17 and is cooled by the heat exchanger 24 and the cooler 25 during that time. In this way, the absorption liquid circulates between the absorption tower 10 and the regeneration tower 20, and the absorption process and the regeneration process are alternately repeated. 1 is provided with a pressure regulating valve 29 in the exhaust pipe 42 of the regeneration tower 20 so that the pressure can be adjusted by pressurizing the interior of the regeneration tower 20 as necessary. Further, although the gas pressure in the absorption tower 10 is set to atmospheric pressure, it may be configured so that the pressure can be adjusted using a pressure control valve in the same manner as the regeneration tower 20, and the carbon dioxide recovery rate of the absorption liquid When it is necessary to increase the pressure, the pressure may be adjusted to a pressure range of about 120 kPaG or less exceeding normal pressure, preferably about 10 to 100 kPaG.

In the recovery device 1, four coolers 14, 25, 27, and 33 are used, and the flow rate of cooling water as a refrigerant is appropriately adjusted according to the cooling efficiency (that is, the cooling temperature) required in each cooler. The The cooling water used in these coolers 14, 25, 27, and 33 is collected by a vaporizing radiator (not shown), cooled by heat radiation by vaporization of water, and then returned to each cooling device. In the present invention, by setting the outlet temperature T2 of the treated gas G ′ of the absorption tower 10 higher than the inlet temperature T1 of the gas G, the amount of cold in the cooler 14 is reduced, so the amount of water vaporized in the vaporizing radiator is reduced. In addition, by using the condensed water of the pretreatment tower 30 as the cooling water W2 of the cooling unit 13, the amount of cold heat in the cooler 14 is further reduced. In the calculation by simulation, in the configuration of FIG. 1, it is possible to reduce the amount of cold heat (about 11% of the total amount of cold heat) of about 0.5 GJ / t-CO ₂ . Therefore, the present invention is effective in reducing the amount of vaporized water in the vaporizer and is advantageous in implementation in an area where water resources are scarce.

  FIG. 2 shows a second embodiment of a recovery apparatus that implements the carbon dioxide recovery method of the present invention. The embodiment of FIG. 2 has a pretreatment tower 30A in which the pretreatment tower 30 of the recovery apparatus 1 of FIG. 1 is changed not only to cool the gas G but also to perform a desulfurization treatment. Since it is the same as the apparatus 1, the description thereof will be omitted below.

  In the recovery device 2 of FIG. 2, the pretreatment tower 30A has a gas-liquid contact portion 31 composed of a filler as in the recovery device 1, but further, a gas that acts as a desulfurization portion for performing a desulfurization process. The liquid contact part 50 is provided under the gas-liquid contact part 31, and the partition member 51 which partitions between these is provided. The partition member 51 has the same structure as the partition member 19 in the absorption tower 10, and is configured by a horizontal annular plate, a tubular wall, and an umbrella part, and is horizontally between the inner wall of the pretreatment tower 30 </ b> A and the tubular wall of the partition member 51. A liquid pool is formed on the annular plate. By driving the pump 32, the cooling water W <b> 1 on the partition member 51 is supplied to the cooler 33 through the circulation path 34 </ b> A, and is supplied above the gas-liquid contact portion 31 after being cooled. Alkaline water B containing a base such as sodium hydroxide is stored at the bottom of the pretreatment tower 30A, and a pump 52 and a circulation path 53 for supplying the alkaline water B to the gas-liquid contact section 50 are provided outside the pretreatment tower 30A. It is attached.

  The gas G containing carbon dioxide (initial temperature T0) supplied to the bottom of the pretreatment tower 30A comes into contact with the alkaline water while passing through the gas-liquid contact section 50, and the sulfur dioxide contained in the gas G or the like. Sulfur oxide is removed by alkaline water, and carbon dioxide having a lower acidity than sulfur oxide passes through the gas-liquid contact portion 50. The gas G (temperature T0 ′) passing through the demister 54 and the partition member 51 from the gas-liquid contact portion 50 is cooled by the cooling water W1 in the gas-liquid contact portion 31 and is generated from the gas G, as in the embodiment of FIG. The condensed water is stored in the liquid pool of the partition member 51 together with the cooling water W <b> 1 to be integrated, and is circulated through the circulation path 34 </ b> A through the cooler 33 by the pump 32. In the circulation path 34A, the increased amount ΔW1 of the increased cooling water W1, that is, an amount of cooling water corresponding to the condensed water generated in the gas-liquid contact portion 31 due to the cooling of the gas G is diverted by the branch path 36A. Is added to the cooling water W2. The gas G (temperature T1) cooled by the gas-liquid contact portion 31 is supplied from the pretreatment tower 30A to the absorption tower 10 after the fine droplets are removed by the demister 35.

  The gas G introduced into the absorption tower 10 comes into contact with the absorbing liquid at the gas-liquid contact portion 11. The treated gas G ′ from which carbon dioxide has been removed in the gas-liquid contact section 11 is cooled in the cooling section 13 through the demister 39 and the partition member 19, and condensed from the treated gas G ′ in the same manner as in the embodiment of FIG. Water is generated and stored in the pool of the partition member 19 together with the cooling water W2. The amount of increase ΔW2 of the cooling water W2 circulating in the circulation path 37, that is, the amount of condensed water generated from the gas G ′ treated in the cooling section 13, and the cooling water ΔW1 supplied from the branch path 36A (of the gas-liquid contact section 31). The total amount with the amount of the condensed water is added to the absorption liquid A1 circulating through the supply path 16 through the branch path 38. The water vaporized from the absorption liquid in the gas-liquid contact portion 11 is supplemented by the water added from the branch path 38, and the concentrated absorption liquid A1 is diluted and recovered to the original concentration.

  In this embodiment, the outlet temperature T2 of the processed gas G ′ cooled by the cooling unit 13 is substantially equal to the temperature T0 ′ before the gas G is cooled by the gas-liquid contact unit 31 of the preprocessing tower 30A. The cooling efficiency of the cooler 14 is set so that the temperatures are equal (practically within T0 ′ ± 3 ° C., preferably within T0 ′ ± 2 ° C.). In the contact between the gas G and the alkaline water B, the temperature rises due to the heat of reaction between the sulfur oxide and the base, but since there is also a cooling effect by the alkaline water B, the initial temperature T0 of the gas G and the gas-liquid contact part 50 The difference from the temperature T0 ′ after passing is not so large and is generally about 1 ° C. or less, so the temperature T0 ′ of the gas G may be regarded as the initial temperature T0. Therefore, also in the recovery device 2 of FIG. 2, the reduced amount of condensed water in the cooling unit 13 by setting the outlet temperature of the treated gas G ′ to T2 (T0 or T0 ′) is the condensation in the pretreatment tower 30. Supplemented with water.

  FIG. 3 shows a third embodiment of a recovery apparatus that implements the carbon dioxide recovery method of the present invention. The recovery device 3 is a modification of the recovery device 2 of FIG. 2 and is provided with an additional cooling unit 60 between the gas-liquid contact unit 11 and the cooling unit 13 of the absorption tower 10A to remove carbon dioxide. The gas G ′ is cooled in two stages of the upstream side cooling unit 60 and the downstream side cooling unit 13, and the condensed water is recovered in both cooling units. The description thereof will be omitted below.

  The pretreatment tower 30A of the recovery device 3 is the same as that of the recovery device 2, and the gas G undergoes the desulfurization process in the gas-liquid contact part 50 and the cooling in the gas-liquid contact part 31, and then the gas G at the temperature T1. Is introduced into the bottom of the absorption tower 10. When the cooling water W1 circulating in the circulation path 34A is increased by the condensed water generated in the gas-liquid contact portion 31, the increase ΔW1 of the cooling water W1 passes through the branch path 36A and the cooling water W2 of the circulation path 37 of the absorption tower 10A. The cooling water W2 circulates between the cooling unit 13 and the cooler 14.

  Between the gas-liquid contact part 11 and the cooling part 13 of the absorption tower 10 </ b> A, an additional cooling part 60 is formed using a filler, and the gas-liquid contact part is formed by a partition member 61 disposed below the cooling part 60. 11. The treated gas G ′ from which carbon dioxide has been removed in the gas-liquid contact part 11 passes through the cooling part 60 and the cooling part 13 and is discharged from the top of the absorption tower 10 after the amount of water vapor is reduced. The cooling mode in the cooling unit 60 is configured to be the same as the modes of the gas-liquid contact unit 31 and the cooling unit 13 of the pretreatment tower 30. Specifically, a pump 62 for supplying the cooling water W3 to the cooling unit 60 and a water-cooled cooler 63 for cooling the cooling water W3 are attached to the outside of the absorption tower 10. Similarly to the partition member 19, the partition member 61 includes a horizontal annular plate, a tubular wall standing on the periphery of the center hole thereof, and an umbrella portion covering the upper end hole of the tubular wall. A liquid pool is formed on the horizontal annular plate between the inner wall and the tubular wall of the partition member 61. The partition member 61 is connected to the pump 62 and the cooler 63 by a circulation path 64, and the cooling water W <b> 3 circulates between the cooling unit 60 and the cooler 63 through the partition member 61 by driving the pump 62. The cooling water W <b> 3 flowing down the cooling unit 60 falls onto the partition member 61 and is stored in the liquid pool, is sent to the cooler 63 through the circulation path 64, is cooled, and is supplied to the cooling unit 60 again. As with the circulation path 34A of the pretreatment tower 30A and the circulation path 37 of the absorption tower 10A, the circulation path 64 is such that the amount of the cooling water W3 circulating through the cooling unit 60 and the cooler 63 is maintained at a predetermined amount. The excess ΔW3 of the cooling water W3 is divided by the branch path 65 that branches from the circulation path 64.

  When the treated gas G ′ passing through the demister 66 and the tubular wall of the partition member 61 from the gas-liquid contact portion 11 reaches the cooling portion 60 on the upstream side and is cooled, condensed water (which may include an absorbent) is generated. Then, it falls onto the partition member 61 together with the cooling water W3 and becomes integrated with the cooling water W3 in the liquid pool, and the cooling water W3 increases. The treated gas G ′ further passes through the demister 39 and the tubular wall of the partition member 19, reaches the cooling unit 13 on the downstream side, and is cooled by the cooling water W <b> 2 to generate condensed water, and the partition member 19 together with the cooling water W <b> 2. The liquid falls and becomes integrated with the cooling water W2 in the liquid pool, and the cooling water W2 increases.

  The downstream end of the branch path 36A branched from the circulation path 34A of the pretreatment tower 30A is connected to the circulation path 37, and the cooling water ΔW1 diverted from the circulation path 34A of the pretreatment tower 30 is also converted into the cooling water W2 of the circulation path 37. As a result, the cooling water W2 increases. Since the circulation path 37 keeps the amount of the circulating cooling water W2 constant, the increase amount ΔW2 of the increased cooling water W2 [that is, the amount of condensed water generated in the cooling unit 13 by the cooling of the treated gas G ′, and the branching Cooling water of the amount of increase ΔW1 (corresponding to the amount of condensed water in the gas-liquid contact portion 31) of the cooling water W1 supplied from the path 36A is diverted by the branch path 38A. The downstream end of the branch path 38A is connected to the circulation path 64, and the increased amount ΔW2 of the cooling water W2 is added to the cooling water W3 of the circulation path 64. The circulation path 64 maintains a constant amount of the cooling water W3 that circulates between the cooling unit 60 and the cooler 63. Therefore, the increase amount ΔW3 of the increased cooling water W3 [that is, the cooling unit is cooled by cooling the treated gas G ′. 13 and the amount of the condensed water generated in the cooling unit 60 and the total amount of the increased amount ΔW1 of the cooling water W1 supplied from the branch path 36A (corresponding to the condensed water in the gas-liquid contact unit 31). The current is diverted by the branch path 65. The downstream end of the branch path 65 is connected to the supply path 16, and the increased amount ΔW3 of the cooling water W3 is added to the absorbing liquid A1 flowing through the supply path 16. This is substantially equivalent to the addition of the condensed water generated in the cooling unit 13 and the cooling unit 60 and the condensed water generated in the pretreatment tower 30 to the absorbing liquid A1 in the supply path 16. And the condensed water condensed in the gas-liquid contact part 31, the cooling part 13, and the cooling part 60 of 30 A of pretreatment towers is utilized as cooling water.

  When the gas G containing carbon dioxide (temperature T1) supplied from the pretreatment tower 30A to the bottom of the absorption tower 10A passes through the gas-liquid contact section 11, the post-treatment gas G ′ from which carbon dioxide has been removed has a temperature of The amount of water vapor increases and the amount of water vapor increases, but while passing through the cooling unit 60 via the partition member 61, the water is cooled to the temperature T3 by the cooling water W <b> 3, and the amount of water vapor decreases. 13 is cooled to the temperature T2 by the cooling water W2 while passing through (T3> T2), and then discharged from the top of the absorption tower 10. The setting of the temperature T3 can also be adjusted by the water temperature of the cooling water W3 and the supply flow rate to the cooling unit 60, similarly to the setting of the temperatures T1 and T2. The amount of water vapor contained in the gas G introduced into the gas-liquid contact part 31 of the pretreatment tower 30A is substantially equal to the amount of water vapor contained in the post-treatment gas G ′ released from the absorption tower 10A. The outlet temperature T2 of the treated gas G ′ cooled by the cooling unit 13 is substantially equal to the temperature T0 ′ before the gas G is cooled by the pretreatment tower 30A (practically T0 ′ ± 3 ° C.). Or less, preferably within T0 ′ ± 2 ° C.). The treated gas G ′ is gradually cooled to the temperature T2 from the gas-liquid contact part 11 through the cooling part 60 and the cooling part 13, and the water vaporized from the absorption liquid in the gas-liquid contact part 11 is gas-liquid. The concentration of the concentrated absorption liquid A1 is compensated by supplying water that is condensed and recovered in the contact portion 31 and the cooling portions 13 and 60 (or an amount of water equivalent thereto) through the branch 65, and is diluted to the original concentration. Restores concentration. That is, even if the outlet temperature of the post-treatment gas G ′ is increased to T <b> 2, the decrease in the condensed water in the cooling unit 13 due to this increase is compensated by the condensed water in the pretreatment tower 30. The condensed water generated in the pretreatment tower 30A is different from the condensed water in the cooling section 60 in that it does not contain an amine compound as an absorbent, so the cooling water W1 in the pretreatment tower 30A is used as the cooling section 13 in the absorption tower 10A. By using in the above, a cleaning action for removing the amine compound from the treated gas G ′ can be expected.

  In the recovery device 3, five coolers 14, 25, 27, 33, and 63 are used. The total amount of cold heat in the cooler 14 and the cooler amount in the cooler 63 is the cooler of the recovery devices 1 and 2. 14, the amount of water vaporized by the vaporizing radiator to cool the cooling water used in the coolers 14, 25, 27, 33, 63 to the original temperature is equal to that of the recovery devices 1, 2. Same as the case. Either the cooler 14 or the cooler 63 may be omitted. In this case, the cooling efficiency of the remaining coolers is increased, and the outlet temperature of the treated gas G ′ is T2 (= T0 ′). Adjust so that

  In the recovery device 3 of FIG. 3, the temperature of the treated gas G ′ rising in the absorption tower 10A gradually decreases to the outlet temperature (T3> T2), but the absorbent that constitutes the absorption liquid to be used is When a component that is likely to accompany the post-treatment gas G ′ (for example, has a relatively low boiling point, has fluorination or volatility, etc.), the cooling efficiency in the cooling unit 60 on the upstream side is increased (that is, cooling is performed). It is possible to reduce the release of the absorbent (by reducing the temperature). However, in this case, since the temperature of the treated gas G ′ that has passed through the cooling unit 60 becomes lower than the outlet temperature T2, the cooling unit 13 and the cooling water W2 on the downstream side do not act as cooling units, but rather heating units and Acts as a heating medium. Below, the collection | recovery apparatus 4 which concerns on embodiment which raised the cooling efficiency of the additional cooling part 60 as mentioned above is demonstrated with reference to FIG. In the recovery device 4, the same components as the cooling unit 13 and the cooling water W2 in FIG. 3 are referred to as a temperature adjustment unit 13 ′ and a temperature adjustment water W2 ′ based on their functions. The part 13 ′ acts as a whole to cool the treated gas G ′ to the outlet temperature T2.

  The recovery device 4 of FIG. 4 has an absorption tower 10B in which the absorption tower 10A in the recovery device 3 is changed as follows. That is, the cooler 14 on the circulation path 37 of the absorption tower 10A is omitted, the heat exchanger 71 is provided between the heat exchanger 24 and the cooler 25 in the reflux path 17, and the temperature adjustment water W2 in the circulation path 37 is provided. Absorbed by changing to form a bypass path 70 that branches and joins from the circulation path 37 so that a part (or all) of 'is diverted (or detoured) through the heat exchanger 71. The tower 10B is configured. The cooling efficiency (cooling temperature) of the cooler 63 in the absorption tower 10B is set to be different from that of the absorption tower 10A, but is structurally similar to the recovery device 3 except for the points described above. The same pretreatment tower 30A and the same regeneration tower 20 as FIGS. Therefore, the gas G introduced into the pretreatment tower 30A of the recovery device 4 undergoes the desulfurization process in the gas-liquid contact part 50 and the cooling in the gas-liquid contact part 31 as in FIGS. In the same manner as in FIGS. 1 to 3, absorption of carbon dioxide by the absorbing liquid, regeneration and circulation of the absorbing liquid are performed. The increased amount ΔW1 of the cooling water W1 increased by the condensed water generated in the gas-liquid contact portion 31 of the pretreatment tower 30A is supplied to the temperature adjustment water W2 ′ of the circulation path 37 through the branch path 36A. At this time, the temperature of the increased amount ΔW1 of the cooling water W1 is increased near T1 due to contact with the gas G.

  In the absorption tower 10B of this embodiment, when the treated gas G ′ from which carbon dioxide has been removed in the gas-liquid contact section 11 is cooled by the cooling water W3 in the cooling section 60, the cooled treated gas G ′. The cooling efficiency of the cooler 63 is set to be high so that the temperature T4 is equal to or lower than the outlet temperature T2, preferably about 5 to 20 ° C. lower than T2. Therefore, the treated gas G ′ cooled to the temperature T4 lower than the outlet temperature T2 in the cooling unit 60 is heated to the temperature T2 by the temperature adjustment water W2 ′ in the temperature adjustment unit 13 ′. In this regard, since the temperature of the cooling water W1 added to the temperature adjustment water W2 ′ is close to T1 (T1 <T2), the above heating is absorbed by the temperature adjustment water W2 ′ of the circulation path 37 and the return path 17. This is realized by heat exchange with the liquid A2. Specifically, a part or all of the temperature adjustment water W2 ′ in the circulation path 37 is supplied to the heat exchanger 71 through the bypass path 70, and functions as cooling water for cooling the absorbing liquid A2 in the heat exchanger 71. It is heated and supplied to the temperature adjustment unit 13 ′. The temperature of the absorbing liquid A2 is generally about 55 to 70 ° C., and the temperature of the temperature adjustment water W2 ′ can be adjusted by the heat exchange rate of the heat exchanger 71, so that the temperature is adjusted to be equal to or higher than T2. As a result, the processed gas G ′ is heated in the temperature adjusting unit 13 ′ and adjusted to the temperature T <b> 2. In this way, the cooling temperature T4 of the treated gas G ′ in the cooling unit 60 is set lower than the outlet temperature T2 (that is, T0 ′), and the temperature of the treated gas G ′ is changed from T4 to T2 by the temperature adjustment water W2 ′. By increasing the cooling efficiency, it is possible to keep the concentration of the absorbing liquid constant while enhancing the cooling efficiency in the cooling unit 60 and strengthening the suppression of the release of the absorbent.

  In the above-described configuration, the amount of condensed water generated from the treated gas G ′ in the cooling section 60 of the absorption tower 10B is greater than or equal to the total amount of condensed water generated in each of the cooling section 13 and the cooling section 60 in the absorption tower 10A of FIG. Become. On the other hand, in the temperature adjusting unit 13 ′, the treated gas G ′ is not cooled, so condensed water is not generated. Rather, the treated gas G ′ is humidified by heating (T 4 <T 2). Since the amount of the temperature adjustment water W2 ′ circulating through the circulation path 37 is configured to be kept constant, the increase ΔW2 that is diverted from the temperature adjustment water W2 ′ of the circulation path 37 to the circulation path 64 through the branch path 38A. 'Decreases by the amount of vaporization due to humidification, compared with the amount of increase ΔW1 of the cooling water W1 supplied from the branch path 36A. The amount of the cooling water W3 that circulates in the circulation path 64 is also maintained constant, and the increased amount ΔW2 ′ of the temperature adjustment water W2 ′ supplied from the branch path 38A and the amount of condensed water generated in the cooling unit 60 The amount of cooling water W3 corresponding to the sum of the above is added from the branch path 65 to the absorbing liquid A1 in the supply path 16 as an increased amount ΔW3. Since the outlet temperature T2 of the treated gas G ′ is the same as that in the embodiment of FIG. 3, the increase amount of the condensed water due to the decrease in the cooling temperature in the cooling unit 60 is the amount of the temperature adjusted water W2 ′ in the temperature adjusting unit 13 ′. The amount of vaporization and the amount of condensed water in the cooling unit 13 in FIG. 3 are equal to each other, and the amount of increase ΔW3 of the cooling water W3 added to the absorption liquid A1 in the supply path 16 is the same as in the embodiment in FIG. .

  In the embodiment of FIG. 4, in order to increase the cooling efficiency in the cooling unit 60, the amount of cold heat in the cooler 63 increases, and the amount of cold heat is equal to or greater than the sum of the cold heat amounts of the cooler 14 and the cooler 63 in FIG. 3. However, the amount of cold heat in the cooler 25 is reduced by using the temperature-adjusted water W2 ′ for cooling the absorbing liquid A2. Accordingly, the entire recovery device 4 is the same as the amount of cold heat in the recovery devices 1 to 3 in FIGS. 1 to 3, and the cooling water used in the coolers 25, 27, 33, and 63 is radiated and cooled by the vaporization radiator. To reduce the amount of vaporized water.

  2 to 4 can also be changed as described in the description of the recovery device 1 in FIG. 1 and corresponds to the condensed water generated in the gas-liquid contact portion 31 and the cooling portions 13 and 60. It is possible to add a quantity of water directly to the absorption liquid without using it as cooling water, or to adopt a cooling mode in which condensed water itself can be added to the absorption liquid.

  In the embodiment of FIGS. 1 to 4, the “predetermined amount” set for each of the circulating cooling waters W1 to W3 and the temperature adjustment water W2 ′ need not be the same, such as the device shape and dimensions. The amount suitable for each part is appropriately set according to the design.

  INDUSTRIAL APPLICABILITY The present invention is effective for reducing the amount of carbon dioxide released and its influence on the environment by using it for the treatment of carbon dioxide-containing gas discharged from facilities such as thermal power plants, steelworks, and boilers. In particular, a recovery device that can reduce the amount of heat generated by cooling water used in carbon dioxide recovery processing is provided, contributing to the promotion of carbon dioxide recovery processing in areas where water resources are scarce and contributing to environmental protection. it can.

1, 2, 3, 4 recovery device, 10, 10A, 10B absorption tower, 20 regeneration tower,
30, 30A pretreatment tower, 11, 21, 31, 50 gas-liquid contact part,
12, 15, 23, 32, 43, 52, 62 pump,
13, 60 cooling section, 13 'temperature adjustment section,
14, 25, 27, 33, 63 cooler, 16 supply path,
17 reflux path, 18 air pipe, 19, 51, 61 partition member,
22 steam heater, 22 ', 34, 34A, 37, 53, 64 circuit,
24,71 heat exchanger, 26 condenser, 28 gas-liquid separator, 29 pressure regulating valve,
35, 39, 40, 41, 54, 66 demister,
36, 36A, 38, 38A, 65 branch path, 70 bypass path,
G, G ′ gas, A1, A2 absorbing liquid, B alkaline water, C recovered gas,
W1, W2, W3 Cooling water, W2 'Temperature adjustment water.

Claims (12)

A pretreatment tower for precooling the gas saturated with water vapor to an appropriate temperature;
The gas cooled in the pretreatment tower is brought into contact with an absorption liquid, and the gas-liquid contact part that absorbs carbon dioxide contained in the gas into the absorption liquid, and the gas that has been processed through the gas-liquid contact part is cooled. An absorption tower having a cooling section;
A regeneration tower that regenerates the absorption liquid by heating the absorption liquid that has absorbed carbon dioxide in the absorption tower to release carbon dioxide;
Water that supplies condensed water generated from the gas by cooling in the pretreatment tower and an amount of water corresponding to the total amount of condensed water generated from the post-treatment gas by cooling in the cooling section of the absorption tower to the absorption liquid A cooling system, and the cooling unit is configured so that a difference between a temperature of the treated gas cooled by the cooling unit and a temperature of the gas before cooled by the pretreatment tower is within 3 ° C. Carbon dioxide recovery device set.   Furthermore, it has a circulation system that circulates the absorption liquid between the absorption tower and the regeneration tower, and the water supply system supplies the absorption liquid supplied from the absorption tower to the regeneration tower by the circulation system, The carbon dioxide recovery device according to claim 1, wherein an amount of water corresponding to a total amount of the condensed water is supplied. A cooling system having a first cooling water as a refrigerant of the pretreatment tower and a second cooling water as a refrigerant of a cooling section of the absorption tower;
The carbon dioxide recovery device according to claim 1 or 2, wherein the water supply system supplies an amount of cooling water corresponding to a total amount of the condensed water from the cooling system to the absorption liquid. The cooling system is configured to separate excess cooling water exceeding a predetermined amount for each of the first cooling water and the second cooling water,
The carbon dioxide supply system according to claim 3, wherein the water supply system has a supply path for supplying the excess cooling water separated from the first cooling water and the second cooling water to the absorption liquid in the cooling system. Recovery device.   In the cooling system, the first cooling water and the second cooling water increase due to the generation of the condensed water, whereby an amount of cooling water corresponding to the condensed water is the excess, and the first cooling water and the The carbon dioxide recovery device according to claim 4, wherein the carbon dioxide recovery device is separated from the second cooling water.   The water supply system has a supply path for adding the first cooling water in an amount corresponding to the condensed water generated in the pretreatment tower to the second cooling water in the absorption tower, and the total amount of the condensed water is The carbon dioxide recovery apparatus according to any one of claims 3 to 5, wherein a corresponding amount of the second cooling water is supplied to the absorption liquid. The cooling section of the absorption tower is composed of an upstream cooling section and a downstream cooling section for the treated gas,
The second cooling water of the cooling system has upstream cooling water as a refrigerant of the upstream cooling unit and downstream cooling water as a refrigerant of the downstream cooling unit, and the upstream cooling water And for each of the cooling water on the downstream side, an excess amount of cooling water exceeding a predetermined amount is separated,
The water supply system includes: a supply path for adding the excess cooling water separated from the first cooling water to the downstream cooling water; and the excess cooling water separated from the downstream cooling water. The carbon dioxide recovery device according to claim 3, further comprising: a supply path for adding to the upstream side cooling water; and a supply path for supplying the excess amount of cooling water separated from the upstream side cooling water to the absorption liquid.   The said cooling system is set so that the temperature of the said processed gas may fall in steps as the said processed gas passes through the said upstream cooling part and the said downstream cooling part. Carbon dioxide recovery device. The cooling section of the absorption tower is composed of an upstream cooling section and a downstream temperature adjusting section for the treated gas,
The second cooling water of the cooling system includes upstream cooling water as a refrigerant of the upstream cooling unit and temperature adjustment water as a medium of the downstream temperature adjustment unit, and the upstream cooling water And for each of the temperature-adjusted water, it is configured so that excess water exceeding a predetermined amount is separated,
The water supply system includes: a supply path for adding the excess cooling water separated from the first cooling water to the temperature adjustment water; and the excess water separated from the temperature adjustment water on the upstream side The carbon dioxide recovery apparatus according to claim 3, further comprising: a supply path for adding cooling water; and a supply path for supplying the excess water separated from the upstream side cooling water to the absorption liquid.   10. The carbon dioxide gas according to claim 9, wherein the cooling system is set so that a temperature of the processed gas that has passed through the upstream cooling unit is lower than a temperature of the processed gas that has passed through the temperature adjusting unit. Recovery device. The pretreatment column is further have a desulfurization section for removing sulfur oxides from the gas prior to cooling, the temperature of the front of the gas to be cooled by the pre-treatment column, after passing through the desulfurizing unit The carbon dioxide recovery apparatus according to any one of claims 1 to 10, wherein the temperature is the temperature of the gas . A pretreatment step for cooling the gas saturated with water vapor to an appropriate temperature in advance;
An absorption step in which the gas cooled in the pretreatment step is brought into contact with an absorption liquid and carbon dioxide contained in the gas is absorbed into the absorption liquid;
A cooling step for cooling the gas after treatment through the absorption step;
A regeneration step of regenerating the absorbing liquid by heating the absorbing liquid that has absorbed carbon dioxide in the absorbing step to release carbon dioxide;
A water supply step of supplying condensed water generated from the gas by cooling in the pretreatment step and an amount of water corresponding to a total amount of condensed water generated from the post-treatment gas in the cooling step to the absorption liquid. The carbon dioxide recovery for adjusting the cooling step so that the difference between the temperature of the post-treatment gas cooled in the cooling step and the temperature of the gas before cooling in the pre-treatment step is within 3 ° C. Method.

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