JP2010235395A - Apparatus for recovering carbon dioxide, and thermal power system with apparatus for recovering carbon dioxide - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for recovering carbon dioxide by which thermal energy supplied from the outside for regeneration of an absorbing liquid can be reduced. <P>SOLUTION: The apparatus for recovering carbon dioxide comprises: an absorption tower for absorbing carbon dioxide in exhaust gas into an absorption liquid; a regeneration tower for regenerating the absorption liquid by dissociating carbon dioxide from the absorption liquid which absorbs carbon dioxide; a piping system which circulates the absorption liquid therethrough between the absorption tower and the regeneration tower; a compressor which sucks gas including carbon dioxide from the regeneration tower and compresses the gas; a heat exchanger which cause the gas discharged from the compressor to exchange heat with the absorption liquid; a separator which separates condensed water produced by cooling the gas by means of the heat exchanger; a first piping path for supplying the absorption liquid held by the regeneration tower from the regeneration tower to the heat exchanger; a second piping path for returning the absorption liquid heated by heat exchange with the gas including carbon dioxide in the heat exchanger from the heat exchanger to the regeneration tower; and a third piping path for returning the condensed water separated by the separator from the separator to the regeneration tower. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a carbon dioxide recovery device and a thermal power generation system including the carbon dioxide recovery device.

  From the viewpoint of preventing global warming, reduction of carbon dioxide emissions is required internationally. Separating and recovering carbon dioxide contained in fossil fuel combustion exhaust gas is one of the effective means for reducing carbon dioxide emissions.

  Japanese Patent Application Laid-Open No. 2005-254212 discloses a means for bringing a combustion exhaust gas containing carbon dioxide and a carbon dioxide absorption liquid into gas-liquid contact, and chemically absorbing carbon dioxide in the absorption liquid to separate it from the combustion exhaust gas. Yes. Here, an amine-based solution has been proposed as an absorbing liquid, and a technique is disclosed in which an absorbing liquid that has absorbed carbon dioxide is heated in a regeneration tower, and carbon dioxide is diffused from the absorbing liquid to be separated and recovered.

  In the technique described in JP-A-2005-254212, in order to dissociate and remove carbon dioxide absorbed in the absorption liquid from the absorption liquid (regeneration of the absorption liquid), the absorption liquid is heated to around 120 ° C. There is a need.

  On the other hand, in Japanese Patent Application Laid-Open No. 2008-29976, the inside of a regeneration tower that regenerates the absorbing liquid by releasing carbon dioxide from the absorbing liquid that has absorbed carbon dioxide is sucked into a low-pressure state by a vacuuming device. A technique for regenerating an absorbing solution under a relatively low temperature condition of ° C is disclosed.

JP-A-2005-254212 JP 2008-29976 A

  In order to regenerate the absorption liquid by dissociating and removing carbon dioxide from the absorption liquid that has absorbed carbon dioxide in the regeneration tower (regeneration), not only the energy of the chemical reaction necessary for the carbon dioxide dissociation reaction but also the absorption liquid In order to promote the dissociation of carbon dioxide by bringing water vapor into gas-liquid contact, the generation energy of water vapor is required. In total, heat energy more than twice that required for chemical reaction is required.

  The techniques described in Japanese Patent Application Laid-Open No. 2005-254212 and Japanese Patent Application Laid-Open No. 2008-29976 require a large amount of thermal energy, although there is a difference in necessary temperature level. When the regeneration tower having the above-described configuration is used as the carbon removal device, exhaust heat that can be used by consuming the thermal energy of the thermal power generation system is reduced, which causes a decrease in power generation efficiency of the thermal power generation system.

  An object of the present invention is to provide a carbon dioxide recovery device capable of reducing heat energy supplied from the outside as heat energy used for regeneration of an absorbing solution.

  Another object of the present invention is to provide a thermal power plant equipped with a carbon dioxide recovery device that can suppress a decrease in power generation efficiency of the power generation system even when a carbon dioxide recovery device that supplies heat energy used for regeneration of the absorbing liquid from the outside is provided. It is to provide a power generation system.

  In the carbon dioxide recovery device of the present invention, an absorption tower that makes gas-liquid contact between an exhaust gas containing carbon dioxide and an absorption liquid of carbon dioxide so that the absorption liquid absorbs carbon dioxide in the exhaust gas, and the absorption tower absorbs carbon dioxide. A regeneration tower that regenerates the absorption liquid by dissociating carbon dioxide from the absorption liquid, and supplies the absorption liquid that has absorbed carbon dioxide in the absorption tower from the absorption tower to the regeneration tower, and In a carbon dioxide recovery apparatus having a piping system for circulating the absorption liquid so as to be supplied from the regeneration tower to the absorption tower, compression for sucking and compressing a gas containing carbon dioxide dissociated in the regeneration tower from the regeneration tower A heat exchanger for exchanging heat with carbon dioxide gas containing carbon dioxide discharged from the compressor, and condensed water produced by cooling the gas containing carbon dioxide with the liquid absorber in the heat exchanger. Min A first piping path for supplying the absorption liquid held by the regeneration tower from the regeneration tower to the heat exchanger, and heat exchange with a gas containing carbon dioxide in the heat exchanger, A second piping path is provided for returning the absorbing liquid heated by heat exchange with the gas containing carbon dioxide in the exchanger to the regeneration tower from the heat exchanger, and condensed water separated by the separator is removed from the separator. A third piping path returning to the regeneration tower is provided.

Further, the thermal power generation system equipped with the carbon dioxide recovery device of the present invention is an absorption tower that makes gas-liquid contact between an exhaust gas containing carbon dioxide and an absorption liquid of carbon dioxide so that the absorption liquid absorbs carbon dioxide in the exhaust gas, A regeneration tower that regenerates the absorption liquid by dissociating carbon dioxide from the absorption liquid that has absorbed carbon dioxide in the absorption tower, and an absorption liquid that has absorbed carbon dioxide in the absorption tower is supplied from the absorption tower to the regeneration tower. The carbon dioxide recovery device having a piping system for circulating the absorption liquid so that the absorption liquid regenerated in the regeneration tower is supplied from the regeneration tower to the absorption tower, the gas containing carbon dioxide dissociated in the regeneration tower is regenerated. A compressor that sucks and compresses from the tower, a heat exchanger that cools the gas containing carbon dioxide discharged from the compressor, and condensed water generated by cooling the gas containing carbon dioxide in the heat exchanger are separated. Including a first piping path for supplying an absorption liquid held in the regeneration tower to the heat exchanger from the regeneration tower, and heat exchange with a gas containing carbon dioxide in the heat exchanger, A second piping path is provided for returning the absorption liquid heated by heat exchange with the gas containing carbon dioxide in the heat exchanger to the regeneration tower from the heat exchanger, and the condensed water separated by the separator is separated. Comprising a third piping path returning from the vessel to the regeneration tower,
An absorption tower that makes gas-liquid contact between an exhaust gas containing carbon dioxide and an absorption liquid of carbon dioxide so that the absorption liquid absorbs carbon dioxide in the exhaust gas, and dissociates carbon dioxide from the absorption liquid that has absorbed carbon dioxide in the absorption tower A regeneration tower for regenerating the absorption liquid, and supplying the absorption liquid that has absorbed carbon dioxide from the absorption tower to the regeneration tower and supplying the absorption liquid regenerated in the regeneration tower to the absorption tower to circulate the absorption liquid. A thermal power generation system having a piping system for causing a compressor, a combustor that burns air and fuel compressed by the compressor to generate combustion gas, a turbine driven by the combustion gas generated by the combustor, and a turbine A generator that generates power by being driven by a turbine, and an exhaust heat recovery boiler that generates steam by recovering heat from the exhaust gas discharged from the turbine by driving the turbine, from the exhaust heat recovery boiler A cooler for cooling the exhaust gas containing carbon dioxide leads to carbon monoxide recovery device is characterized in that disposed at the inlet of the said carbon dioxide recovery device.

  According to the present invention, when carbon dioxide is separated and recovered from combustion exhaust gas containing carbon dioxide, it is possible to realize a carbon dioxide recovery device capable of reducing the heat energy supplied from the outside as the heat energy used for regeneration of the absorbent. .

  In addition, according to the present invention, even when a carbon dioxide recovery device that supplies heat energy used for regeneration of the absorbing liquid from the outside is provided, the carbon dioxide recovery device that can suppress a decrease in power generation efficiency of the power generation system is provided. A thermal power generation system can be realized.

1 is a schematic system diagram showing a thermal power generation system including a carbon dioxide recovery device according to an embodiment of the present invention. The situation figure of the various state quantities in the regeneration tower of the carbon dioxide recovery device in the thermal power generation system provided with the carbon dioxide recovery device of one example of the present invention shown in FIG. The situation figure of various state quantities in the compressor of the carbon dioxide recovery device by one example of the present invention. The situation figure of various state quantities in the absorption liquid reheater of the carbon dioxide recovery device by one example of the present invention. The situation figure of various state quantities in each apparatus of the carbon dioxide recovery device by one example of the present invention. The schematic system diagram which shows the carbon dioxide recovery apparatus by the other Example of this invention. The situation figure of the various state quantity in each apparatus of the carbon dioxide recovery apparatus in the thermal power generation system provided with the carbon dioxide recovery apparatus of the other Example of this invention shown in FIG. The schematic system diagram which shows the carbon dioxide recovery apparatus in the thermal power generation system provided with the carbon dioxide recovery apparatus of the further another Example of this invention.

  Next, a carbon dioxide recovery device according to an embodiment of the present invention and a thermal power generation system including the carbon dioxide recovery device will be described below with reference to the drawings.

  A carbon dioxide recovery device that is an embodiment of the present invention and a thermal power generation system including the carbon dioxide recovery device will be described with reference to FIG.

  FIG. 1 is a schematic system diagram of a thermal power generation system provided with a carbon dioxide recovery device according to an embodiment of the present invention. The thermal power generation system of the present embodiment is a combined cycle in which a gas turbine device and a steam turbine device are combined.

  The gas turbine device is generated by a compressor 2 that compresses and discharges air 3, a combustor 4 that mixes and burns air discharged from the compressor 2 and fuel (not shown), and combustion in the combustor 4. The turbine 1 driven by the combustion gas is the main equipment. The shafts of the compressor 2 and the turbine 1 are connected to a generator 21 that is rotated by the turbine 1 via a reduction gear (not shown), and the electric power generated by the generator 21 can be transmitted to the system.

  The exhaust gas 5 of the turbine 1 is guided as a heat source to the exhaust heat recovery steam generator 12 via the exhaust gas duct, and the steam generated by heat exchange with the exhaust gas in the exhaust heat recovery steam generator 12 passes through the pipe 6. Then, the steam turbine 13 is supplied to drive the steam turbine 13.

  The steam turbine 13 rotates the generator 22 to generate electric power, and the electric power generated by the generator 22 can be transmitted to the system. Further, the steam discharged from the steam turbine 13 is cooled by the condenser 14 to become condensed water, and the condensed water whose pressure has been increased by the condensed water pump 15 returns to the exhaust heat recovery steam generator 12 through the pipe 7. .

  On the other hand, the exhaust gas 5 discharged from the exhaust heat recovery steam generator 12 is guided to the carbon dioxide recovery device 10 installed on the downstream side of the exhaust heat recovery steam generator 12 via the exhaust gas duct 53. Yes.

  The main components of the carbon dioxide recovery device 10 provided in the thermal power generation system of this embodiment are an aqueous potassium carbonate solution (hereinafter referred to as an absorption liquid) that is an absorption liquid of carbon dioxide and exhaust heat recovery steam discharged from the turbine 1. An absorption tower 81 that makes gas-liquid contact with the exhaust gas 5 supplied through the exhaust gas duct 53 via the generator 12 and absorbs carbon dioxide contained in the exhaust gas 5 in the absorption liquid, and on the downstream side of the absorption tower 81 The absorption liquid that has absorbed carbon dioxide in the exhaust gas 5 in the absorption tower 81 (hereinafter referred to as rich solution) and water vapor supplied through the pipe 38 are brought into gas-liquid contact to dissociate the carbon dioxide absorbed in the absorption liquid. A regeneration tower 82 is installed.

  A mixed gas of carbon dioxide and water vapor (hereinafter referred to as CO2 rich gas) dissociated from the absorbing solution in the regeneration tower 82 is sucked from the regeneration tower 82 through a pipe 32 and is supplied to a plurality of compressors 60a and 60b that compress the CO2 rich gas. Supplied.

  The CO2 rich gas compressed by the compressors 60a and 60b is sequentially supplied to the absorption liquid reheaters 83a and 83b through the pipes 33a and 33b, and is cooled by heat exchange in the absorption liquid reheaters 83a and 83b.

  The CO2 rich gas that has passed through the absorption liquid reheaters 83a and 83b is cooled by a cooler 85c that cools the CO2 rich gas to a lower temperature.

  The moisture contained in the CO2 rich gas is condensed by the cooling by the absorbent reheaters 83a and 83b and the cooler 85c. Therefore, the CO2 rich gas containing the condensed water condensed in the absorption liquid reheaters 83a and 83b and the cooler 85c is separated from the absorption liquid reheaters 83a and 83b and the cooler 85c, respectively. It supplies to 61b and 61c, and condensate water is isolate | separated from CO2 rich gas.

  The condensed water separated from the CO 2 rich gas by the separators 61a and 61b is collected through the pipes 36a and 36b, joined to the pipe 38, and supplied to the regeneration tower 82.

  The condensed water separated from the CO2 rich gas by the separator 61c flows down through the pipe 36c, joins the pipe 38 through the pipe 37b and is supplied to the regeneration tower 82, and passes through the pipe 37c. After passing through the cooler 85a, the refrigerant is divided into one that joins the pipe 38 and is supplied to the regeneration tower 82.

  The exhaust gas duct 53 on the upstream side of the absorption tower 81 causes the exhaust gas 5 discharged from the turbine 1 and flowing through the exhaust heat recovery steam generator 12 to flow down to be supplied to the absorption tower 81. A cooler 85 a for cooling the exhaust gas 5 supplied to 81 is installed.

  In addition, a pipe 30 that supplies an absorption liquid (hereinafter referred to as a lean solution) after releasing carbon dioxide in the regeneration tower 82 installed on the downstream side of the absorption tower 81 to the absorption tower 81 includes: A cooler 85b for cooling the lean solution is installed.

  The absorption tower 81 is provided with a spray nozzle (not shown) in an upper space, and has a structure capable of spraying an absorption liquid to the exhaust gas 5 flowing inside the absorption tower 81. The absorption tower 81 has a function of absorbing the carbon dioxide in the exhaust gas 5 into the absorption liquid by bringing the exhaust gas 5 and the absorption liquid into gas-liquid contact on the surface of the built-in packing.

  The lower part of the absorption tower 81 is a container capable of storing the absorption liquid, and this container part is the upper part of the packing of the regeneration tower 82 installed on the downstream side of the absorption tower 81 by the pipe 31 provided with the pump 92. The absorption liquid stored in the lower part of the absorption tower 81 is supplied to the regeneration tower 82 through the pipe 31. The upper space of the absorption tower 81 is connected to a stack (not shown) by an exhaust gas duct 54.

  The regenerator 82 has a built-in packing, and has a function of dissociating carbon dioxide in the rich solution by bringing the rich solution and water vapor into gas-liquid contact on the surface of the packing.

  A pipe 30 in which a pump 90 and a cooler 85b are arranged in series is connected to the lower space of the regeneration tower 82, and a spray nozzle (see FIG. 5) in the upper space of the absorption tower 81 is connected by the pipe 30 downstream of the cooler 85b. The rich solution stored in the lower part of the regeneration tower 82 is supplied to the absorption tower 81 through the pipe 30.

  Further, the lower space of the regeneration tower 82 is connected to a pipe provided with a pump 91 by a pipe, and the outlet pipe of the pump 91 is branched into pipes 37a, 37b, and 37c arranged in parallel, and each pipe 37a. , 37b, 37c are connected to the heated fluid passages of the absorption liquid reheaters 83a, 83b and the cooler 85d, respectively.

  Further, a pipe 37c on the downstream side of the cooler 85d is connected to the cooler 85a, and each outlet pipe of the heated fluid flow path of the absorption liquid reheaters 83a and 83b and the cooler 85a is a pipe. The pipe 38 is connected to the lower space of the regeneration tower 82.

  Next, operation | movement of the thermal power generation system provided with the carbon dioxide recovery apparatus by a present Example is demonstrated using FIG.

  In FIG. 1, air sucked from the intake duct 3 is compressed by the compressor 2 after dust and the like are removed by an unillustrated intake filter. The compressed air discharged from the compressor 2 is supplied to the combustor 4.

  In the combustor 4, air is combusted together with fuel to generate high-temperature combustion gas. This high-temperature combustion gas is supplied to the turbine 1, and passes through stationary blades and moving blades (not shown) inside the turbine 1, so that thermal energy is converted into rotational kinetic energy through a Brayton cycle expansion process. The

  The rotational kinetic energy is consumed in driving the compressor 2 connected to the shaft of the turbine 1 and is extracted as electric energy by driving the generator 21.

  The exhaust gas 5 discharged from the turbine 1 by driving the turbine 1 flows into the exhaust heat recovery boiler 12, and the condensate supplied from the condenser 14 via the pipe 7 in the exhaust heat recovery boiler 12. Steam is generated by heating.

  The steam generated in the exhaust heat recovery boiler 12 is supplied to the steam turbine 13 through the pipe 6, rotates the steam turbine 13, and is taken out as electrical energy by the generator 22.

  The steam that has passed through the steam turbine 13 is condensed in the condenser 14 to become condensate, and is supplied as feed water to the exhaust heat recovery boiler 12 via the pipe 7 by the condensate pump 15.

  On the other hand, the temperature of the exhaust gas 5 whose heat has been recovered by the exhaust heat recovery boiler 12 is lowered to about 100 ° C. and flows from the exhaust heat recovery boiler 12 into the cooler 85a of the carbon dioxide recovery device 10 via the exhaust gas duct 53. .

  In the cooler 85 a, the exhaust gas 5 is cooled to about 50 ° C. by heat exchange between the rich solution and the exhaust gas 5, and the rich solution that is the heated side fluid is heated to about 80 ° C.

  The exhaust gas 5 cooled to about 50 ° C. by the cooler 85a is introduced into the absorption tower 81 constituting the carbon dioxide recovery device 10 and is sprayed from the upper spray nozzle on the surface of the packing in the tower at a temperature of about 50 ° C. Make gas-liquid contact with absorbent. The internal pressure of the absorption tower 81 is close to atmospheric pressure and is about 100 kPa.

  In the carbon dioxide recovery apparatus 10 of the present embodiment, an aqueous potassium carbonate solution is assumed as an absorption liquid that absorbs carbon dioxide in the exhaust gas 5 by the absorption tower 81, and about 3 volume percent of carbon dioxide contained in the exhaust gas 5 is Most of it is absorbed by the absorbent. The exhaust gas 5 that has been absorbed and removed by this absorption liquid flows down from the absorption tower 81 through the exhaust gas duct 54 and is discharged into the atmosphere via a stack (not shown).

  The absorption liquid (rich solution) collected in the lower container of the absorption tower 81 has a temperature of about 60 ° C. due to the reaction heat when absorbing the carbon dioxide in the exhaust gas 5, and is pressurized by the pump 92 and passes through the pipe 31. And supplied to the upper space of the packing of the regeneration tower 82 installed on the downstream side of the absorption tower 81.

  The regeneration tower 82 is adjusted to about 30 kPa, which is lower than the atmospheric pressure, by the action of the compressor 60 a communicating with the regeneration tower 82 through the pipe 32. In the regeneration tower 82, a part of the lean solution collected in the lower part of the container is pressurized by the pump 91 and passed through the pipes 37a, 37b, 37c to the absorbent reheaters 83a, 83b, the cooler 85d, and the cooler 85a, respectively. Have been supplied.

  Since the high temperature CO2 rich gas is supplied from the compressors 60a and 60b through the pipes 33a and 33b to the absorption liquid reheaters 83a and 83b, the absorption liquid reheaters 83a and 83b are discharged from the compressors 60a and 60b. The lean solution is heated to about 80 ° C. by heat exchange between the high temperature CO 2 rich gas and the lean solution.

  In the cooler 85d disposed in the pipe 37c, the lean solution flowing through the pipe 37c is cooled to 40 ° C. by the cooling water, but the exhaust gas 5 and the heat are heated in the cooler 85a disposed on the downstream side of the cooler 85d. In exchange, the lean solution is heated to about 80 ° C.

  The lean solution heated to about 80 ° C. by the absorption liquid reheaters 83 a and 83 b and the cooler 85 a joins in the pipe 38 and then returns to the lower portion of the regeneration tower 82.

  At this time, the saturation temperature of the water vapor corresponding to the pressure in the regeneration tower 82 is about 70 ° C., a part of the lean solution returned from the pipe 38 evaporates inside the regeneration tower 82, and the evaporated vapor is in the regeneration tower 82. The rich solution that flows upward in the interior and falls from above is in gas-liquid contact with the surface of the filling.

  The rich solution is heated by this gas-liquid contact, and becomes thermal energy for dissociating carbon dioxide absorbed in the rich solution, and carbon dioxide is dissociated inside the regeneration tower 82.

  The rich solution from which carbon dioxide has been dissociated is changed into a lean solution and collected in the lower part of the regeneration tower 82. A part of the lean solution collected in the lower part of the regeneration tower 82 is again pressurized by the pump 91, supplied to the absorbent reheaters 83a and 83b through the pipes 37a and 37b, and the coolers 85d and 85a through the pipes 37d. To be supplied.

  On the other hand, another part of the lean solution collected in the lower part of the regeneration tower 82 is pressurized by the pump 90, supplied to the cooler 85b through the pipe 30, and cooled to about 50 ° C. through heat exchange with the cooling water. . The lean solution cooled to 50 ° C. is supplied to the spray nozzle in the upper space of the absorption tower 81 through the pipe 30 and again absorbs carbon dioxide in the exhaust gas 5 to become CO 2 rich gas in which carbon dioxide and water vapor are mixed.

  The CO 2 rich gas mainly composed of carbon dioxide and water vapor reaching the upper part of the regeneration tower 82 is pressurized from a pressure of 30 kPa to about 170 kPa by the compressor 60a supplied through the pipe 32, while the temperature is about 60 ° C. to about 190 ° C. The temperature is raised to ° C.

  The CO 2 rich gas of about 190 ° C. is supplied from the compressor 60a to the absorbent reheater 83a through the pipe 33a, and heat-exchanges with the lean solution to lower the temperature to about 70 ° C. and heats the lean solution to about 80 ° C. .

  Since about 70% of the water vapor is condensed in the CO2 rich gas cooled to about 70 ° C. by the absorbent reheater 83a, the condensed water is separated and collected by the separator 61a installed downstream of the absorbent reheater 83a. To do.

  The condensed water separated and collected by the separator 61 a is returned to the lower part of the regeneration tower 82 via the pipe 36 a and the pipe 38. The remaining CO2-rich gas is sucked into the compressor 60b installed on the downstream side of the separator 61a, and the pressure is increased from about 170 kPa to about 1000 kPa, while the temperature is increased from about 70 ° C to about 200 ° C.

  The reason why the CO2 rich gas is increased to about 1000 kPa is that the dew point temperature of water vapor is increased to facilitate separation of moisture, and the pressure condition for supplying to the subsequent carbon dioxide liquefaction step (not shown). It is because it is suitable.

  The CO 2 rich gas of about 200 ° C. is supplied from the compressor 60b to the absorbent reheater 83b through the pipe 33b, and heat-exchanges with the lean solution to lower the temperature to about 70 ° C. and heats the lean solution to about 80 ° C. .

  Since 90% or more of the water vapor is condensed in the CO2 rich gas cooled to about 70 ° C. by the absorbent reheater 83b, the condensed water is separated and collected by the separator 61b installed on the downstream side of the absorbent reheater 83b. To do.

  The condensed water separated and collected by the separator 61b is returned to the lower part of the regeneration tower 82 via the pipe 36b and the pipe 38. The remaining CO 2 rich gas is cooled to about 40 ° C. by a cooler 85c installed on the downstream side of the separator 61b, and condensed water is separated and collected by the separator 61c installed on the downstream side of the cooler 85c.

  The condensed water separated and collected by the separator 61c joins the pipe 37b through the pipe 36c, is supplied to the absorption liquid reheater 83b, is heated to about 80 ° C., and then is regenerated through the pipe 38. Returned to the bottom of the tower 82.

  The CO2 rich gas after separating the condensed water by the separator 61c has a carbon dioxide concentration of about 99%, and is sent to the subsequent carbon dioxide liquefaction step (not shown).

  Next, the advantages of the carbon dioxide recovery device 10 of the present embodiment will be described with reference to FIGS. 2 to 5 from the viewpoint of heat utilization necessary for the regeneration of the absorbing solution. These FIG. 2 to FIG. 5 show a comparison of state quantities such as temperature and pressure in each device when the pressure in the regeneration tower 82 is changed.

  When the pressure inside the regeneration tower 82 is changed, the inlet pressure of the compressor 60a also changes, but the pressure ratio between the compressor 60a and the compressor 60b is set so that the pressure at the outlet of the compressor 60b is always about 1000 kPa. Calculated in conjunction.

  FIG. 2 shows various state quantities in the regeneration tower 82, and FIG. 2 (a) shows the change in the saturation temperature of water vapor corresponding to the pressure in the regeneration tower 82. As shown in the figure, the temperature of the absorption liquid is set to be about 8 ° C. lower than the saturation temperature, and the absorption liquid is heated by the absorption liquid reheater 83 to a temperature higher than the saturation temperature. The plan was to evaporate the water inside.

  At this time, in the regeneration tower 82, the partial pressure of water vapor becomes the saturation pressure of the temperature of the absorbing liquid, and the state of the partial pressure of water vapor and the partial pressure of carbon dioxide is as shown in FIG. When the partial pressure of CO2 rich gas is sucked into the compressor 60a from the regeneration tower 82, the amount of water vapor evaporated per mass of carbon dioxide is as shown in FIG.

  FIG. 3 shows the status of various state quantities in the compressors 60a and 60b. As shown in FIG. 3A, the compressor 60a and the compressor 60a are arranged so that the pressure at the outlet of the compressor 60b is always about 1000 kPa. The pressure ratio of 60b is changed. The pressure ratios of these compressors are not necessarily the same, but in this embodiment, it is assumed that the pressure ratios of the compressors 60a and 60b are the same. Further, the flow rates sucked by the compressors 60a and 60b are as shown in FIG. 3B when converted to the mass of carbon dioxide.

  The change in the flow rate of the compressor 60a reflects the evaporation amount shown in FIG. 2C, and the flow rate decreases as the pressure in the regeneration tower 82 decreases. On the other hand, the flow rate of the compressor 60b on the downstream side is obtained by subtracting the condensation amount of the flow rate absorption liquid reheater 83a described later in FIG. 4C from the flow rate of the compressor 60a, and is the same as in the case of the compressor 60a. The flow rate of the compressor 60b decreases as the pressure in the tower decreases.

  The power of these compressors 60a and 60b is determined according to the flow rate and pressure ratio of the fluid to be compressed. Therefore, as shown in FIG. Since it is large, the power is large in the low pressure region.

  FIG. 4 shows the state of various state quantities in the absorbent reheaters 83a and 83b, and FIG. 4 (a) shows the gas inlet / outlet temperature of the absorbent reheater 83a. The inlet gas temperature is determined by the gas temperature inside the regeneration tower 82 and the pressure ratio of the compressor 60a. The lower the pressure in the tower, the higher the temperature. On the other hand, the outlet gas temperature of the absorbent reheater 83a is determined by the temperature of the absorbent in the regeneration tower 82, which is the heated fluid of the absorbent reheater 83a.

  FIG. 4B similarly shows the gas inlet / outlet temperature of the absorbent reheater 83b. The inlet gas temperature is higher when the pressure in the tower is lower due to the effect of the pressure ratio of the compressor 60b. Similarly, the outlet gas temperature is determined by the temperature of the absorption liquid in the regeneration tower 82 which is the heated fluid of the absorption liquid reheater 83b.

  From the gas outlet temperatures of the absorption liquid reheaters 83a and 83b in FIGS. 4A and 4B and the evaporation amount in FIG. 2C, the amount of water vapor condensed in the absorption liquid reheaters 83a and 83b is shown in FIG. As shown in 4 (c).

  When the pressure in the regeneration tower 82 is low, the amount of water vapor evaporated in the tower is small, but the outlet gas temperature of the absorbent reheater 83a is low. On the other hand, when the pressure in the tower is high, the amount of water vapor evaporated increases, but the outlet gas temperature of the absorbent reheater 83a increases. Due to these synergistic effects, the amount of condensation in the absorption liquid reheater 83a is almost constant regardless of the pressure in the tower.

  On the other hand, since the amount of water vapor flowing into the absorption liquid reheater 83b is obtained by subtracting the amount of condensation in the absorption liquid reheater 83a from the evaporation amount, the flow into the absorption liquid reheater 83b increases as the pressure in the tower increases. The amount of steam to be increased.

  Further, since the pressure increases in the absorption liquid reheater 83b and the dew point temperature increases, most of the water vapor that has flowed in condenses, and the amount of condensation in the absorption liquid reheater 83b increases when the pressure in the tower is high. To increase. In the cooler 85c, the remaining water vapor evaporates.

  FIG. 5 shows various calorific values and exhaust gas temperature conditions in the regeneration tower 82, the absorption liquid reheaters 83a and 83b, and the cooler 85a. In the regeneration tower 82, carbon dioxide is released from the absorption liquid, The amount of heat required for regeneration is shown in FIG. The energy of the chemical reaction for dissociating carbon dioxide from the absorption liquid and the energy required for evaporating water vapor in the regeneration tower 82 are roughly divided. The energy required for the chemical reaction does not depend on the pressure in the tower, but the evaporation energy. Changes in proportion to the amount of evaporation in FIG.

  On the other hand, FIG. 5B shows the amount of heat that can be recovered by cooling and condensing the CO2 rich gas by the absorption liquid reheaters 83a and 83b, and the amount of heat that can be recovered from the exhaust gas by the cooler 85a. Comparing the magnitude of latent heat and sensible heat in the process of cooling the CO2 rich gas, the latent heat released by the condensation of water vapor is overwhelmingly large, and the amount of heat that can be recovered by the absorption liquid reheaters 83a and 83b is shown in FIG. It almost corresponds to the amount of water vapor condensation described in (c).

  FIG. 5B also shows the amount of heat recovered by the cooler 85a, which is necessary to cover all heat utilization necessary for regeneration of the absorbing solution. In order for the cooler 85a to recover this amount of heat, it is necessary to supply the exhaust gas having the temperature shown in FIG. 5C to the cooler 85a.

  When the pressure in the regeneration tower 82 is high, the amount of heat generated by the compressor is small, so that the necessary exhaust gas temperature is higher. However, it is relatively easy to take out and use the exhaust gas of about 110 ° C. from the thermal power generation system, and according to this embodiment, it is possible to regenerate the absorbing liquid in the regeneration tower 82 without an external heat source.

  In this embodiment, the packing type is exemplified as the absorption tower 81 or the regeneration tower 82, but the basic action necessary for these devices is gas-liquid contact, and a generally known system such as a shelf type or a spray type is used. It can be arbitrarily selected from the formula.

  Further, as the cooler 85a or the absorption liquid reheater 83, heat exchange between the heated fluid and the heated fluid is assumed by a single heat exchanger, but a secondary loop using an intermediate medium such as water is configured. Thus, a method of exchanging heat is also possible.

  Furthermore, in this embodiment, an aqueous potassium carbonate solution is assumed as the absorbing solution, but other absorbing solutions such as an MEA (monoethanolamine) aqueous solution can be used. The temperature conditions necessary for absorption or regeneration, the amount of heat required, and the like differ depending on the type of the absorbing solution, and the system operating conditions may be designed according to the selected absorbing solution. In this case, it goes without saying that the pressure in the regeneration tower 82 that minimizes the compressor power is also different from that of the present embodiment.

  In the present embodiment, a combined cycle in which a gas turbine and a steam turbine are combined is illustrated as a thermal power generation system including the carbon dioxide recovery device 10, but a HAT in which a gas turbine, a humidification tower, a regenerative heat exchanger, and the like are combined. It can also be implemented in cycles. In that case, since the exhaust gas of the gas turbine contains about 20% moisture and the exhaust gas has a large amount of latent heat energy, the amount of heat that can be recovered by the cooler 85a increases and the regeneration of the absorption liquid is further facilitated. There are advantages.

  According to this embodiment, when carbon dioxide is separated and recovered from combustion exhaust gas containing carbon dioxide, a carbon dioxide recovery device capable of reducing the heat energy supplied from the outside as the heat energy used for the regeneration of the absorbent is realized. it can.

  In addition, according to this embodiment, the carbon dioxide recovery device that can suppress the reduction in power generation efficiency of the power generation system is provided even when the carbon dioxide recovery device that supplies heat energy used for regeneration of the absorbing liquid from the outside is provided. A thermal power generation system can be realized.

  Next, a carbon dioxide recovery device according to another embodiment of the present invention and a thermal power generation system including the carbon dioxide recovery device will be described with reference to FIG.

  The carbon dioxide recovery device of the present embodiment shown in FIG. 6 and the thermal power generation system including the carbon dioxide recovery device include the carbon dioxide recovery device and the carbon dioxide recovery device of the previous embodiment shown in FIG. Since the basic configuration is the same as that of the thermal power generation system, the description of the configuration common to both is omitted, and only the configuration that is different will be described below.

  In FIG. 6, in the carbon dioxide recovery device provided in the thermal power generation system of the present embodiment, the compressor 60a is the only compressor that compresses the CO2 rich gas from the regeneration tower 82 in the carbon dioxide recovery device 10. This is different from that of the embodiment.

  The pressure ratio and the compression power of the compressor 60a of the carbon dioxide recovery device 10 in this embodiment are shown in FIGS. 7 (a) and 7 (b), respectively.

  As shown in FIGS. 7 (a) and 7 (b), the compressor 60a compresses to about 1000 kPa without cooling in the middle, so the compression power of the compressor 60a is the compressor 60a of the above embodiment. From 1.6 times to 2 times. In addition, FIG. 7C shows the exhaust gas temperature at the inlet of the cooler 85a to cover the exhaust heat necessary for the regeneration tower 82.

  As shown in FIG. 7 (c), since the heat generated with the pressure increase in the compressor 60a is large, the inlet exhaust gas temperature of the cooler 85a is the same as that of the cooler 85a of the embodiment shown in FIG. 5 (c). The temperature is about several degrees Celsius lower than the inlet exhaust gas temperature.

  Since the influence on the plant thermal efficiency is larger when the compressor power is changed from about 1.6 times to about 2 times than when the exhaust gas temperature is changed by several degrees C., the plant thermal efficiency of the carbon dioxide recovery apparatus is the above-described first embodiment. Lower than. However, the number of compressors and heat exchangers can be reduced, and there is an advantage that the carbon dioxide recovery device of the previous embodiment can be reduced from the viewpoint of reducing the plant construction cost of the carbon dioxide recovery device.

  According to this embodiment, when carbon dioxide is separated and recovered from combustion exhaust gas containing carbon dioxide, a carbon dioxide recovery device capable of reducing the heat energy supplied from the outside as the heat energy used for the regeneration of the absorbent is realized. it can.

  In addition, according to this embodiment, the carbon dioxide recovery device that can suppress the reduction in power generation efficiency of the power generation system is provided even when the carbon dioxide recovery device that supplies heat energy used for regeneration of the absorbing liquid from the outside is provided. A thermal power generation system can be realized.

  Next, a carbon dioxide recovery device that is still another embodiment of the present invention and a thermal power generation system including the carbon dioxide recovery device will be described with reference to FIG.

  The thermal power generation system including the carbon dioxide recovery device and the carbon dioxide recovery device of the present embodiment shown in FIG. 8 includes the carbon dioxide recovery device and the carbon dioxide recovery device of the previous embodiment shown in FIG. Since the basic configuration is the same as that of the thermal power generation system, the description of the configuration common to both is omitted, and only the configuration that is different will be described below.

  In FIG. 8, in the carbon dioxide recovery device 10 provided in the thermal power generation system of the present embodiment, it is installed at the inlet of the carbon dioxide recovery device 10 and is used as the heated fluid of the cooler 85a that cools the exhaust gas 5 of the gas turbine. The point that the cooling water such as the river water 56 is used is different from that of the previous embodiment.

  Along with the use of cooling water such as river water 56 for the cooler 85a, a part of the lean solution is branched from the regeneration tower 82 and supplied to the cooler 85a, and the branched pipe 37c is supplied to the branch pipe 37c. It differs from the previous embodiment in that the installed cooler 85d is not installed.

  Further, in the carbon dioxide recovery apparatus 10 of the present embodiment, a pipe 37d that is newly branched from the pipe 37c that pressurizes and supplies the lean solution from the regeneration tower 82 and reaches the pipe 38 is disposed, and the pipe 37d has an absorbing liquid. A reheater 83c is installed, and the lean solution introduced from the regeneration tower 82 through the pipe 37c and the pipe 37d in the absorption liquid reheater 83c is heated by the steam 55 extracted from an exhaust heat recovery boiler or the like. This is also different from the previous embodiment.

  In the carbon dioxide recovery device 10 of the present embodiment, the external cooling water 56 having a relatively stable temperature is used as the cooling water for the cooler 85a to cool the exhaust gas 5 flowing down from the exhaust gas duct 53. Operating conditions become more stable.

  As the external cooling water 56, river water, cooling water exchanged with seawater, or cooling water cooled by a cooling tower is used.

  On the other hand, since the steam 55 extracted from the exhaust heat recovery boiler 12 (not shown) or the like is consumed as a heating source of the absorption liquid reheater 83c, the plant thermal efficiency is lower than that of the first embodiment.

  In the present embodiment having the above-described configuration, the number of heat exchangers can be further reduced, so that the equipment cost of the thermal power generation system can be reduced.

  According to this embodiment, when carbon dioxide is separated and recovered from combustion exhaust gas containing carbon dioxide, a carbon dioxide recovery device capable of reducing the heat energy supplied from the outside as the heat energy used for the regeneration of the absorbent is realized. it can.

  In addition, according to this embodiment, the carbon dioxide recovery device that can suppress the reduction in power generation efficiency of the power generation system is provided even when the carbon dioxide recovery device that supplies heat energy used for regeneration of the absorbing liquid from the outside is provided. A thermal power generation system can be realized.

  The present invention can be used in a carbon dioxide recovery device and a thermal power generation system including the carbon dioxide recovery device.

  1: turbine, 2: compressor, 3: intake duct, 4: combustor, 5: exhaust gas, 10: carbon dioxide recovery device, 12: exhaust heat recovery boiler, 13: steam turbine, 14: condenser, 15: Pump, 21, 22: Generator, 30, 31, 32, 33a, 33b, 36a, 36b, 36c, 37a, 37b, 37c, 37d, 38: Piping, 53, 53: Exhaust gas duct, 55: Water vapor, 56: External cooling water, 81: absorption tower, 82: regeneration tower, 83a, 83b, 83c: absorption liquid reheater, 85a, 85b: cooler, 90, 91, 92: pump.

Claims (8)

An absorption tower that makes gas-liquid contact between an exhaust gas containing carbon dioxide and an absorption liquid of carbon dioxide so that the absorption liquid absorbs carbon dioxide in the exhaust gas, and carbon dioxide is dissociated from the absorption liquid that has absorbed carbon dioxide in the absorption tower. A regeneration tower that regenerates the absorption liquid, and an absorption liquid that has absorbed carbon dioxide in the absorption tower is supplied from the absorption tower to the regeneration tower, and an absorption liquid regenerated in the regeneration tower is supplied from the regeneration tower to the absorption tower. In the carbon dioxide recovery device having a piping system for circulating the absorption liquid,
A compressor that sucks and compresses a gas containing carbon dioxide dissociated in the regeneration tower, compresses the gas containing carbon dioxide discharged from the compressor with an absorbing liquid, and the heat A separator for separating condensed water produced by cooling a gas containing carbon dioxide with an absorbing liquid in an exchanger,
A first piping path is provided for supplying the absorption liquid held by the regeneration tower from the regeneration tower to the heat exchanger, and heat exchange with a gas containing carbon dioxide is performed in the heat exchanger, and the heat exchanger performs carbon dioxide oxidation. A second piping path is provided for returning the absorption liquid heated by heat exchange with the gas containing carbon from the heat exchanger to the regeneration tower, and condensed water separated by the separator is transferred from the separator to the regeneration tower. A carbon dioxide recovery device comprising a third piping path to be returned. In the carbon dioxide recovery device according to claim 1,
The compressor is constituted by a plurality of compressors arranged in series, and the heat exchanger is arranged on the downstream side of the plurality of compressors to cool a gas containing carbon dioxide discharged from the compressor. A plurality of heat exchangers, and the separators are respectively disposed on the downstream side of the plurality of heat exchangers, and the condensed water generated by cooling the gas containing carbon dioxide in the heat exchangers is separated. The second pipe is constituted by a plurality of separators, and the first pipe path is branched to sequentially supply the absorption liquid held in the regeneration tower to the plurality of heat exchangers. The path is arranged to return the absorption liquid heated by exchanging heat with the gas containing carbon dioxide in the plurality of heat exchangers to the regeneration tower, and the third piping path is separated by the separator The condensed water is returned from the separator to the regeneration tower. Carbon dioxide recovery apparatus characterized by being arranged to. In the carbon dioxide recovery device according to claim 1,
A fourth piping path that branches from the first piping path and supplies the absorbing liquid to the second piping path is disposed, and another heat exchanger is installed in the fourth piping path. A carbon dioxide recovery apparatus, characterized in that the absorption liquid flowing down the four piping paths is further heated. In the carbon dioxide recovery device according to claim 1,
River water is supplied as a cooling medium to a cooler disposed at the inlet of the carbon dioxide recovery device, and the exhaust heat is used as a heat source for another heat exchanger installed in the fourth piping path. A carbon dioxide recovery device configured to supply steam generated by a recovery boiler. An absorption tower that makes gas-liquid contact between an exhaust gas containing carbon dioxide and an absorption liquid of carbon dioxide so that the absorption liquid absorbs carbon dioxide in the exhaust gas, and carbon dioxide is dissociated from the absorption liquid that has absorbed carbon dioxide in the absorption tower. A regeneration tower that regenerates the absorption liquid, and an absorption liquid that has absorbed carbon dioxide in the absorption tower is supplied from the absorption tower to the regeneration tower, and an absorption liquid regenerated in the regeneration tower is supplied from the regeneration tower to the absorption tower. The carbon dioxide recovery device having a piping system for circulating the absorption liquid so as to suck and compress the gas containing carbon dioxide dissociated in the regeneration tower from the regeneration tower, and discharged from the compressor A heat exchanger that cools the gas containing carbon dioxide; and a separator that separates condensed water generated by cooling the gas containing carbon dioxide in the heat exchanger; From the tower An absorption liquid provided with a first piping path to be supplied to the heat exchanger, heat exchanged with a gas containing carbon dioxide in the heat exchanger, and heated by heat exchange with the gas containing carbon dioxide in the heat exchanger A second piping path that returns the heat exchanger to the regeneration tower, and a third piping path that returns the condensed water separated by the separator to the regeneration tower,
An absorption tower that makes gas-liquid contact between an exhaust gas containing carbon dioxide and an absorption liquid of carbon dioxide so that the absorption liquid absorbs carbon dioxide in the exhaust gas, and dissociates carbon dioxide from the absorption liquid that has absorbed carbon dioxide in the absorption tower A regeneration tower for regenerating the absorption liquid, and supplying the absorption liquid that has absorbed carbon dioxide from the absorption tower to the regeneration tower and supplying the absorption liquid regenerated in the regeneration tower to the absorption tower to circulate the absorption liquid. A thermal power generation system having a piping system for causing a compressor, a combustor that burns air and fuel compressed by the compressor to generate combustion gas, a turbine driven by the combustion gas generated by the combustor, and a turbine A generator that generates power by being driven by a turbine, and an exhaust heat recovery boiler that generates steam by recovering heat from the exhaust gas discharged from the turbine by driving the turbine, from the exhaust heat recovery boiler Thermal power generation system provided with a carbon dioxide recovery apparatus, wherein a cooler that is disposed at the inlet of the carbon dioxide recovery apparatus for cooling the exhaust gas containing carbon dioxide leads to carbon dioxide recovery apparatus. In the thermal power generation system provided with the carbon dioxide recovery device according to claim 5,
The compressor is constituted by a plurality of compressors arranged in series, and the heat exchanger is arranged on the downstream side of the plurality of compressors to cool a gas containing carbon dioxide discharged from the compressor. A plurality of heat exchangers, and the separators are respectively disposed on the downstream side of the plurality of heat exchangers, and the condensed water generated by cooling the gas containing carbon dioxide in the heat exchangers is separated. The second pipe is constituted by a plurality of separators, and the first pipe path is branched to sequentially supply the absorption liquid held in the regeneration tower to the plurality of heat exchangers. The path is arranged to return the absorption liquid heated by exchanging heat with the gas containing carbon dioxide in the plurality of heat exchangers to the regeneration tower, and the third piping path is separated by the separator The condensed water is returned from the separator to the regeneration tower. Thermal power generation system provided with a carbon dioxide recovery apparatus, characterized in that disposed on the. In the thermal power generation system provided with the carbon dioxide recovery device according to claim 5,
A fourth piping path that branches from the first piping path and supplies the absorbing liquid to the second piping path is disposed, and another heat exchanger is installed in the fourth piping path. A thermal power generation system provided with a carbon dioxide recovery device, characterized in that the absorption liquid flowing down the four piping paths is further heated. In the thermal power generation system provided with the carbon dioxide recovery device according to claim 5,
It is configured to supply external cooling water as a cooling medium to a cooler disposed at the inlet of the carbon dioxide recovery device, and as a heating source of another heat exchanger installed in the fourth piping path A thermal power generation system equipped with a carbon dioxide recovery device, characterized in that steam generated by an exhaust heat recovery boiler is supplied.

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