JP7843386B2 - Carbon dioxide capture equipment - Google Patents

Description

Embodiments of this invention relate to carbon dioxide capture equipment.

In recent years, measures to reduce carbon dioxide ( _CO2 ) emissions have been promoted as a way to combat global warming. In this context, carbon dioxide capture and storage (CCS) technology, which captures and stores carbon dioxide, is attracting attention. Specifically, carbon dioxide capture facilities are being considered that use absorbent liquids to capture carbon dioxide contained in exhaust gases (hereinafter referred to as exhaust gases) emitted from thermal power plants, steel plants, and waste treatment plants.

In this carbon dioxide capture system, exhaust gas is supplied to an absorption tower. In the absorption tower, the carbon dioxide contained in the exhaust gas is absorbed by an absorbent solution containing amines and water. The exhaust gas, from which the carbon dioxide has been removed, is then discharged from the absorption tower.

The absorbent liquid that has absorbed carbon dioxide is supplied to the regeneration tower. In the regeneration tower, the absorbent liquid releases carbon dioxide. At this time, the released carbon dioxide is discharged from the regeneration tower along with steam and separated and recovered. The absorbent liquid that has released carbon dioxide in the regeneration tower is returned to the absorption tower.

Here, a reboiler is connected to the regeneration tower. The reboiler heats the absorbent solution, which is an amine aqueous solution, to a temperature of approximately 110-130°C. A heat transfer medium is supplied to the reboiler for heating the absorbent solution.

The temperature of the heat transfer medium introduced into the reboiler is limited to 200°C or below to prevent deterioration of the absorbent liquid. In other words, to heat the absorbent liquid to the aforementioned temperature while maintaining a temperature below 200°C, the temperature of the heat transfer medium is set within a narrow range.

For example, steam generated in a plant is used as the heat transfer medium introduced into a reboiler. By appropriately controlling the steam pressure, the latent heat associated with the phase change from steam to water can be utilized during heat exchange between the steam (heat transfer medium) and the absorbent liquid in the reboiler. In this way, using steam allows the heat source temperature of the reboiler to be maintained within a narrow range.

Patent No. 6806833

The temperature and flow rate of steam from the plant that is introduced into the reboiler as a heat transfer medium vary depending on the plant's operating conditions. Therefore, depending on the plant's operating conditions, it may be necessary to mix high-temperature and low-temperature steam before supplying it to the reboiler, or to supply steam that has undergone pressure reduction or temperature reduction. Thus, conventional carbon dioxide capture equipment does not effectively utilize the energy of the steam generated in plants.

Furthermore, the steam flow rate generated in plants does not necessarily match the steam flow rate used in the plants and reboilers. Therefore, for example, if the steam flow rate used in the reboilers is insufficient, the fuel flow rate supplied to the plants is increased to increase the generated steam flow rate.

On the other hand, if the flow rate of steam generated in a plant exceeds the flow rate of steam used in the plant and reboiler, the excess steam is discharged outside the system.

The problem that this invention aims to solve is to provide a carbon dioxide recovery system that can effectively utilize the heat supplied from external facilities such as plants in a reboiler, and can properly heat the absorbent liquid in the reboiler.

The carbon dioxide recovery equipment of this embodiment includes an absorption tower into which exhaust gas to be treated containing carbon dioxide is introduced and which absorbs carbon dioxide into an absorbent liquid containing water; a regeneration tower that releases carbon dioxide from the absorbent liquid supplied from the absorption tower; a reboiler that heats the absorbent liquid in the regeneration tower to generate steam; a heat storage unit that generates steam from the absorbent liquid in the reboiler and stores heat for supplying a reboiler heat transfer medium at a reboiler allowable temperature to the reboiler; and a heating and supply mechanism that heats the heat storage unit and has a configuration for supplying the heat stored in the heat storage unit to the reboiler. Furthermore, the heating and supply mechanism includes a heat storage unit heat transfer medium supply pipe that supplies a first heat transfer medium, which is excess heat transfer medium that satisfies the reboiler allowable temperature generated in an external facility, to the heat storage unit; a heat storage unit heat transfer medium discharge pipe that discharges the first heat transfer medium from the heat storage unit; and circulation piping that circulates a circulating heat transfer medium that functions as the reboiler heat transfer medium to the heat storage unit and the reboiler.

When heat is stored in the heat storage unit, the first heat transfer medium introduced to the heat storage unit via the heat transfer medium supply pipe provides the heat to the heat storage unit and is discharged from the heat storage unit via the heat transfer medium discharge pipe. When heat is released from the heat storage unit, the circulating heat transfer medium introduced to the heat storage unit via the circulation piping removes the heat from the heat storage unit to meet the allowable temperature of the reboiler and is supplied to the reboiler via the circulation piping.

This is a diagram of the carbon dioxide capture equipment according to the first embodiment. This is a diagram of the reboiler heat transfer medium supply mechanism in the carbon dioxide recovery facility according to the first embodiment. This is a diagram of a reboiler heat transfer medium supply mechanism with a different configuration in the carbon dioxide recovery equipment of the first embodiment. This figure schematically shows the configuration of a heat storage device equipped with a chemical heat storage material in a reboiler heat transfer medium supply mechanism of a different configuration in the carbon dioxide recovery equipment of the first embodiment. This is a diagram of the reboiler heat transfer medium supply mechanism in a carbon dioxide recovery facility according to a second embodiment. This diagram schematically shows the configuration of a heat storage device with a different configuration in the carbon dioxide capture facility of the second embodiment. This diagram schematically shows the configuration of a heat storage device with a different configuration in the carbon dioxide capture facility of the second embodiment. This is a diagram of the reboiler heat transfer medium supply mechanism in a carbon dioxide recovery facility according to a third embodiment. This is a diagram of the reboiler heat transfer medium supply mechanism in a carbon dioxide recovery facility according to the fourth embodiment. This is a diagram of the reboiler heat transfer medium supply mechanism of another configuration in the carbon dioxide recovery equipment of the fourth embodiment.

The embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment)
Figure 1 is a system diagram of the carbon dioxide recovery equipment 10 according to the first embodiment. Figure 2 is a system diagram of the reboiler heat medium supply mechanism 50A in the carbon dioxide recovery equipment 10 according to the first embodiment. Figure 2 mainly shows the configuration of the reboiler heat medium supply mechanism 50A in the carbon dioxide recovery equipment 10.

As shown in Figure 1, the carbon dioxide capture equipment 10 comprises an absorption tower 20, a regeneration tower 30, a reboiler 40, and a reboiler heat transfer medium supply mechanism 50A.

The absorption tower 20 receives the exhaust gas to be treated (exhaust gas) containing carbon dioxide, and allows the carbon dioxide to be absorbed by an absorbent liquid containing water. Hereafter, the exhaust gas to be treated will be referred to as "exhaust gas." The absorption tower 20 includes an absorption section 21 that brings the exhaust gas and the dispersed, falling absorbent liquid into gas-liquid contact.

A lean liquid inlet pipe 37 is connected to the top of the absorption tower 20 to supply the absorption liquid (lean liquid 32, described later) from the regeneration tower 30 to the absorption tower 20. The lean liquid 32 is dispersed from above the absorption section 21.

An exhaust gas inlet pipe 24 is connected to the lower part of the absorption tower 20 to introduce exhaust gas into the absorption tower 20. The exhaust gas inlet pipe 24 is connected to the absorption tower 20, for example, at a position between the liquid level of the absorbent liquid (which has absorbed carbon dioxide and accumulated at the bottom) and the absorption section 21. The exhaust gas inlet pipe 24 is equipped with an exhaust gas blower 24a that pressurizes and pumps the exhaust gas into the absorption tower 20.

Exhaust gas is introduced into the absorption section 21 from below and upward, and the absorbent liquid is introduced into the absorption section 21 from above and downward. Then, in the absorption section 21, the exhaust gas and the absorbent liquid are brought into gas-liquid contact, causing the absorbent liquid to absorb carbon dioxide.

Here, the absorbent liquid that absorbs carbon dioxide in the absorption tower 20 is referred to as the rich liquid 23. The rich liquid 23 accumulates at the bottom of the absorption tower 20. Note that the rich liquid 23 is stored below the absorption section 21. Furthermore, the upper end of the absorption tower 20 is equipped with an outlet 22 for discharging the exhaust gas from which carbon dioxide has been removed.

The exhaust gas introduced into the absorption tower 20 is not particularly limited, as long as it contains carbon dioxide. Examples of such exhaust gases include those emitted from thermal power plants, steel mills, and waste incineration plants.

The absorbent solution preferably uses an amine-based aqueous solution, such as monoethanolamine or diethanolamine. However, the absorbent solution is not limited to these types of amines. The absorbent solution may consist of an aqueous solution containing one or more types of amines.

The regeneration tower 30 releases carbon dioxide from the absorbent liquid that has absorbed the carbon dioxide supplied from the absorption tower 20. The regeneration tower 30 includes a regeneration section 31 that brings the steam generated in the reboiler 40 into gas-liquid contact with the absorbent liquid that has absorbed the dispersed, falling carbon dioxide.

A rich liquid inlet pipe 25 is connected to the upper part of the regeneration tower 30 to supply the rich liquid 23 from the absorption tower 20 to the regeneration tower 30. The rich liquid 23 is dispersed from above the regeneration section 31.

Steam is introduced from the bottom to the top of the regeneration section 31, and the rich liquid 23 is introduced from the top to the bottom of the regeneration section 31. Then, in the regeneration section 31, the steam and the rich liquid 23 are brought into gas-liquid contact, releasing carbon dioxide from the rich liquid 23. Here, the absorbent liquid from which carbon dioxide has been released in the regeneration tower 30 is called the lean liquid 32. The lean liquid 32 accumulates at the bottom of the regeneration tower 30. Note that the lean liquid 32 is stored below the regeneration section 31.

Furthermore, the upper end of the regeneration tower 30 is equipped with a carbon dioxide outlet 33 for discharging carbon dioxide released from the rich liquid 23. The carbon dioxide outlet 33 is connected to the gas-liquid separator 35 via a carbon dioxide discharge pipe 34. The carbon dioxide discharge pipe 34 is also equipped with a cooler 36 for condensing the water vapor discharged along with the carbon dioxide from the carbon dioxide outlet 33.

The gas-liquid separator 35 separates carbon dioxide from the water produced in the cooler 36. The upper end of the gas-liquid separator 35 is equipped with a recovery port 35a for recovering carbon dioxide. Furthermore, the bottom of the gas-liquid separator 35 is equipped with a drain pipe 35b that returns the water separated by the gas-liquid separator 35 back to the regeneration tower 30. The drain pipe 35b is connected to the regeneration tower 30, for example, at a position above the regeneration section 31.

Furthermore, a reboiler 40 is connected to the regeneration tower 30. The reboiler 40 heats the lean liquid 32 accumulated at the bottom of the regeneration tower 30. The reboiler 40 is equipped with a circulation pipe 41 that introduces the lean liquid 32 from the regeneration tower 30 and returns the heated lean liquid 32, which contains steam, back to the regeneration tower 30.

In the reboiler 40, steam is generated by heating the lean liquid 32 through heat exchange between the heat transfer medium supplied from the reboiler heat transfer medium supply mechanism 50A and the lean liquid 32 supplied from the regeneration tower 30. The lean liquid 32 is heated to approximately 110-130°C in the reboiler 40. The reboiler heat transfer medium supply mechanism 50A will be described later.

By heating the lean liquid 32 to this temperature range, vapor can be generated in the regeneration unit 31 to bring it into gas-liquid contact with the rich liquid 23. Furthermore, heating to this temperature range can suppress the deterioration of the absorbent liquid.

A rich liquid introduction pipe 25 is provided between the bottom of the absorption tower 20 and the top of the regeneration tower 30 to introduce the rich liquid 23 from the absorption tower 20 to the regeneration tower 30. Here, as mentioned above, the rich liquid introduction pipe 25 is connected to the regeneration tower 30 at a position above the regeneration section 31.

The rich liquid inlet pipe 25 passes through the heat exchanger 26 and is connected to the regeneration tower 30. The rich liquid inlet pipe 25 is also equipped with a rich liquid pump 27 that pumps the rich liquid 23 from the absorption tower 20 to the regeneration tower 30.

Furthermore, a lean liquid introduction pipe 37 is provided between the bottom of the regeneration tower 30 and the top of the absorption tower 20 to introduce lean liquid 32 from the regeneration tower 30 to the absorption tower 20. Here, as mentioned above, the lean liquid introduction pipe 37 is connected to the absorption tower 20 at a position above the absorption section 21.

The lean liquid inlet pipe 37 is connected to the absorption tower 20 via the heat exchanger 26. In the heat exchanger 26, heat exchange occurs between the rich liquid 23 flowing through the rich liquid inlet pipe 25 and the lean liquid 32 flowing through the lean liquid inlet pipe 37.

The lean liquid inlet pipe 37 is equipped with a lean liquid pump 38 that pumps the lean liquid 32 from the regeneration tower 30 to the absorption tower 20. The lean liquid inlet pipe 37 is also equipped with, for example, a cooler 39 for cooling the lean liquid 32.

Here, we will explain the operation of the carbon dioxide capture equipment 10. The operation of the reboiler heat transfer medium supply mechanism 50A will be described later.

The exhaust gas introduced into the lower part of the absorption tower 20 from the exhaust gas inlet pipe 24 flows upward through the absorption section 21. The lean liquid 32 introduced into the upper part of the absorption tower 20 from the lean liquid inlet pipe 37 disperses and flows downward through the absorption section 21. In the absorption section 21, the exhaust gas and the lean liquid 32 come into gas-liquid contact, absorbing the carbon dioxide contained in the exhaust gas into the lean liquid 32, thereby generating a rich liquid 23.

The exhaust gas, after contact with the lean liquid 32, has carbon dioxide removed and is discharged from the outlet 22 of the absorption tower 20.

The generated rich liquid 23 is temporarily stored at the bottom of the absorption tower 20. The rich liquid 23 stored at the bottom is introduced into the heat exchanger 26 through the rich liquid inlet pipe 25. In the heat exchanger 26, the rich liquid 23 is heated through heat exchange with the lean liquid 32 flowing through the lean liquid inlet pipe 37. The heated rich liquid 23 is then introduced into the regeneration tower 30.

The lean liquid 32 stored at the bottom of the regeneration tower 30 is introduced into the reboiler 40 through the circulation piping 41. The lean liquid 32 introduced into the reboiler 40 is heated through heat exchange with the heat transfer medium introduced from the reboiler heat transfer medium supply mechanism 50A. Steam (water vapor) is then generated from the heated lean liquid 32. During this process, carbon dioxide may also be released from the lean liquid 32.

The generated steam, along with carbon dioxide, is supplied to the lower part of the regeneration tower 30. The steam supplied to the lower part of the regeneration tower 30 flows upward through the regeneration section 31. Meanwhile, the rich liquid 23 introduced from the absorption tower 20 to the regeneration tower 30 disperses and flows downward through the regeneration section 31.

In the regeneration section 31, the rich liquid 23 and vapor come into gas-liquid contact, releasing carbon dioxide from the rich liquid 23 and generating the lean liquid 32. In this way, the absorbent liquid is regenerated in the regeneration tower 30.

The generated lean liquid 32 is temporarily stored at the bottom of the regeneration tower 30. The lean liquid 32 stored at the bottom is introduced into the heat exchanger 26 through the lean liquid inlet pipe 37. In the heat exchanger 26, the lean liquid 32 is cooled by heat exchange with the rich liquid 23 flowing through the rich liquid inlet pipe 25. The cooled lean liquid 32 is further cooled by the cooler 39 and introduced into the absorption tower 20. In this way, the absorbent liquid circulates between the absorption tower 20 and the regeneration tower 30.

Furthermore, in the regeneration unit 31, carbon dioxide released from the rich liquid 23, and steam that comes into contact with the rich liquid 23, are discharged from the carbon dioxide outlet 33. The carbon dioxide and steam discharged from the carbon dioxide outlet 33 pass through the carbon dioxide discharge pipe 34 and are introduced into the cooler 36. In the cooler 36, the steam (water vapor) condenses into water. Then, the carbon dioxide and water are introduced into the gas-liquid separator 35, where they are separated into carbon dioxide and water.

Carbon dioxide is recovered in a designated recovery section via the recovery port 35a. Water is introduced from the gas-liquid separator 35 to the regeneration tower 30 via the drain pipe 35b.

Next, the reboiler heat transfer medium supply mechanism 50A will be described.

The reboiler heat transfer medium supply mechanism 50A is configured to supply a heat transfer medium to the reboiler 40. As shown in Figure 2, the reboiler heat transfer medium supply mechanism 50A includes a reboiler heat transfer medium supply pipe 60, a reboiler heat transfer medium discharge pipe 61, a heating supply mechanism 70A, and a heat storage device 80.

The reboiler heat transfer medium supply pipe 60 is connected to the reboiler 40 and supplies the reboiler heat transfer medium 62, which heats the absorbent liquid (lean liquid 32), to the reboiler 40. The reboiler heat transfer medium discharge pipe 61 is connected to the reboiler 40 and discharges the reboiler heat transfer medium 62, which has heated the absorbent liquid (lean liquid 32), from the reboiler 40.

Here, the reboiler heat transfer medium 62 is, for example, steam (water vapor) generated at a thermal power plant, steel mill, or waste treatment plant equipped with a carbon dioxide capture facility 10. The temperature of the reboiler heat transfer medium 62 supplied to the reboiler 40 is set to, for example, approximately 130 to 200°C.

The temperature range that is permissible for the heat transfer medium supplied to the reboiler 40 is referred to as the reboiler's permissible temperature. By setting the temperature within this range, the lean liquid 32 can be heated to the aforementioned temperature range in the reboiler 40, while simultaneously suppressing the deterioration of the absorbent liquid.

For example, if the carbon dioxide capture equipment 10 is installed alongside a thermal power plant equipped with a steam turbine, the steam extracted from the steam turbine is used as the reboiler heat transfer medium 62. In this case, the reboiler heat transfer medium 62, which has condensed into water in the reboiler 40, is introduced into the feedwater pipe between the condenser and the boiler via the reboiler heat transfer medium discharge pipe 61.

The heating and supply mechanism 70A is configured to heat the heat storage section 81 of the heat storage device 80 and to supply the amount of heat stored in the heat storage section 81 to the reboiler 40. As shown in Figure 2, the heating and supply mechanism 70A includes a connecting pipe 71, a heat transfer medium discharge pipe 72, and a heat transfer medium supply pipe 73 for the heat storage section.

The connecting pipe 71 connects the reboiler heat transfer medium supply pipe 60 and the heat storage unit 81. One end of the connecting pipe 71 is connected to the reboiler heat transfer medium supply pipe 60, and the other end is connected to the heat storage unit 81. The connecting pipe 71 is equipped with, for example, a temperature detection unit 75 that detects the temperature of the heat transfer medium flowing through it.

The heat transfer fluid discharge pipe 72 discharges the reboiler heat transfer fluid 62 supplied from the reboiler heat transfer fluid supply pipe 60 to the heat storage unit 81 via the connecting pipe 71. For example, if the carbon dioxide recovery equipment 10 is installed in a thermal power plant equipped with a steam turbine, the reboiler heat transfer fluid 62 that condenses into water in the heat storage unit 81 is introduced into the feedwater pipe between the condenser and the boiler via the heat transfer fluid discharge pipe 72.

The heat transfer medium discharge pipe 72 is equipped with a flow control valve 72a. Furthermore, the heat transfer medium discharge pipe 72 is also equipped with a temperature detection unit 76 for detecting the temperature of the reboiler heat transfer medium 62 discharged from the heat storage device 80.

The heat storage unit heat transfer medium supply pipe 73 supplies the heat storage unit heat transfer medium 74, which is at a temperature lower than the reboiler heat transfer medium 62, to the heat storage unit 81. The heat storage unit heat transfer medium supply pipe 73 is equipped with a flow control valve 73a. For example, low-temperature steam (water vapor) generated in the aforementioned plant is used as the heat storage unit heat transfer medium 74.

The heat storage device 80 includes a heat storage section 81 that stores the amount of heat used to heat the absorbent liquid in the reboiler 40. The heat storage section 81 comprises a latent heat storage material or a sensible heat storage material. The heat storage section 81 is constructed, for example, by filling a predetermined container with these heat storage materials. The heat storage device 80 is constructed by housing the heat storage section 81 within a predetermined device container.

Latent heat storage materials are heat storage materials that store heat by utilizing the phase change of a substance. Latent heat storage materials are constructed by filling an outer shell (shell) or container, such as a resin, with a latent heat storage material. For example, a latent heat storage material that undergoes a phase change between 130 and 200°C is used. This temperature range corresponds to the allowable temperature of a reboiler. However, the latent heat storage material may be heated beyond the phase change temperature (melting point). In this case, for example, sensible heat is stored while the latent heat storage material is in a liquid state. The upper limit temperature for sensible heat storage in the latent heat storage material is 200°C, corresponding to the upper limit of the allowable temperature of a reboiler.

By using a material that undergoes a phase change within this temperature range, the temperature of the reboiler heat transfer medium 62 supplied to the reboiler 40 can be brought to the reboiler's allowable temperature. In the case of latent heat storage materials, this temperature range is the set heating temperature. Specifically, examples of latent heat storage materials include polyethylene, sugar alcohols such as erythritol and mannitol, and paraffin.

When using latent heat storage material as the heat storage material, the heat storage section 81 is constructed by filling a predetermined container with multiple latent heat storage materials. In this case, the latent heat storage materials exchange heat with, for example, a fluid flowing through the gaps between the latent heat storage materials.

Sensible heat storage materials are materials that store heat energy resulting from temperature changes. Examples of sensible heat storage materials include rocks, concrete, and ceramics. The temperature range used for sensible heat storage is, for example, 130 to 200°C. This temperature range corresponds to the allowable temperature of a reboiler.

By using this temperature range, the temperature of the reboiler heat transfer medium 62 supplied to the reboiler 40 can be brought to the reboiler's allowable temperature. In the case of latent heat storage material, this temperature range represents the set heating temperature.

When using a sensible heat storage material as the heat storage material, the heat storage section 81 is constructed by filling a predetermined container with multiple sensible heat storage materials. In this case, the sensible heat storage materials exchange heat with, for example, a fluid flowing through the gaps between them.

Next, the operation of the reboiler heat transfer medium supply mechanism 50A will be explained.

First, we will explain the process of heat storage in the heat storage device 80.

When storing heat in the heat storage device 80, the conditions for the reboiler heat transfer medium 62 supplied to the reboiler heat transfer medium supply pipe 60 are as follows:

The temperature of the reboiler heat transfer medium 62 is within the reboiler's allowable temperature. Furthermore, the reboiler heat transfer medium 62 supply source can supply more than the flow rate required by the reboiler 40 to the reboiler heat transfer medium supply pipe 60. In other words, in the plant that serves as the reboiler heat transfer medium 62 supply source, heat storage treatment is performed when excess heat transfer medium is generated, for example, during high-load operation.

When heat is stored in the heat storage device 80, the flow control valve 72a is open and the flow control valve 73a is closed. A portion of the reboiler heat transfer medium 62 flowing through the reboiler heat transfer medium supply pipe 60 is introduced into the heat storage section 81 of the heat storage device 80 via the connecting pipe 71. At this time, any reboiler heat transfer medium 62 exceeding the set flow rate supplied to the reboiler 40 is introduced into the heat storage section 81.

Furthermore, the reboiler heat transfer medium 62 supplied to the reboiler 40 through the reboiler heat transfer medium supply pipe 60 heats the lean liquid 32 flowing through the circulation pipe 41 in the reboiler 40. The reboiler heat transfer medium 62, having heated the lean liquid 32, is then discharged through the reboiler heat transfer medium discharge pipe 61.

The reboiler heat transfer medium 62 introduced into the heat storage unit 81 flows between the heat storage materials filled in the unit, transferring heat to the materials. As a result, the heat storage unit 81 stores heat.

The reboiler heat transfer medium 62, having supplied heat to the heat storage material, condenses into water and is discharged through the heat transfer medium discharge pipe 72.

In the process of storing heat in the heat storage unit 81, if the temperature of the reboiler heat transfer medium 62 detected by the temperature detection unit 76 is equal to the temperature of the reboiler heat transfer medium 62 introduced into the heat storage unit 81 via the communication pipe 71, the flow rate control valve 72a is closed. Specifically, for example, if the temperature of the reboiler heat transfer medium 62 detected by the temperature detection unit 76 is equal to the temperature of the reboiler heat transfer medium 62 detected by the temperature detection unit 75, the flow rate control valve 72a is closed. In this case, it means that the amount of heat stored in the heat storage unit 81 has exceeded the upper limit of heat storage capacity.

Next, the process of heat dissipation in the heat storage device 80 will be explained.

When heat is released in the heat storage device 80, the conditions for the reboiler heat transfer medium 62 supplied to the reboiler heat transfer medium supply pipe 60 are as follows:

The temperature of the reboiler heat transfer medium 62 is within the reboiler's allowable temperature. However, the supply source for the reboiler heat transfer medium 62 cannot supply the required flow rate to the reboiler heat transfer medium supply pipe 60. In other words, in the plant that supplies the reboiler heat transfer medium 62, heat dissipation is performed when the supply amount of heat transfer medium decreases, for example, during low-load operation.

When heat is released from the heat storage device 80, the flow control valve 72a is closed and the flow control valve 73a is open. The heat storage unit heat transfer medium 74 is introduced into the heat storage unit 81 from the heat storage unit heat transfer medium supply pipe 73. The flow rate of the heat storage unit heat transfer medium 74 introduced into the heat storage unit 81 is adjusted by the flow control valve 73a to compensate for the insufficient flow rate of the reboiler heat transfer medium 62.

The heat transfer medium 74 introduced into the heat storage unit 81 flows between the heat storage materials filled in the unit, absorbing heat from the materials and being heated. During this process, the heat transfer medium 74 is heated to the reboiler's allowable temperature.

During the process of releasing heat from the heat storage unit 81, when the temperature of the heat storage unit's heat transfer medium 74, as detected by the temperature detection unit 75, falls below a lower threshold, the flow rate control valve 73a is closed. When the temperature of the heat storage unit's heat transfer medium 74 discharged from the heat storage unit 81 falls below the lower threshold, it means that the amount of heat stored in the heat storage unit 81 has fallen below the lower heat storage limit. When the heat storage limit is exceeded, the heat storage unit 81 does not have enough heat stored to heat the heat storage unit's heat transfer medium 74 to the reboiler's allowable temperature.

Here, the lower threshold is set to, for example, 130°C. This value is the lower limit of the reboiler's allowable temperature.

The heated heat storage unit heat transfer medium 74 is introduced into the reboiler heat transfer medium supply pipe 60 via the connecting pipe 71. In the reboiler heat transfer medium supply pipe 60, the heat storage unit heat transfer medium 74 and the reboiler heat transfer medium 62 are mixed, and a mixed heat transfer medium at an optimal flow rate is supplied to the reboiler 40.

The mixed heat transfer medium supplied to the reboiler 40 heats the absorbent liquid flowing through the circulation pipe 41 within the reboiler 40. The heated mixed heat transfer medium is then discharged through the reboiler heat transfer medium discharge pipe 61.

Furthermore, in the operation of the reboiler heat transfer medium supply mechanism 50A described above, the control of flow control valves 72a, 73a, etc., based on the detection signals from the temperature detection units 75, 76, may be performed, for example, via a control device. This also applies to the following embodiments.

According to the carbon dioxide recovery equipment 10 of the first embodiment described above, when excess heat transfer medium is generated in a plant or other facility that is a source of reboiler heat transfer medium 62 due to high-load operation, the heat storage device 80 can store the heat contained in the excess heat transfer medium. Furthermore, even when the supply of heat transfer medium decreases due to low-load operation of the plant or other facility, the heat stored in the heat storage device 80 can be used to compensate for the reduced supply of heat transfer medium.

Thus, the carbon dioxide capture system 10 can effectively utilize the surplus heat generated by external facilities such as plants in the reboiler 40. Furthermore, even if load fluctuations occur in external facilities such as plants, which are the source of the reboiler heat transfer medium 62, the reboiler 40 can properly heat the absorbent liquid.

Furthermore, by providing the reboiler heat transfer medium supply mechanism 50A, the flow rate of the reboiler heat transfer medium 62 supplied to the reboiler 40 can be adjusted to an appropriate flow rate.

Here, the configuration of the reboiler heat transfer medium supply mechanism 50A in the carbon dioxide capture equipment 10 is not limited to the configuration shown in Figure 2.

Figure 3 is a diagram of a reboiler heat transfer medium supply mechanism 50A with a different configuration in the carbon dioxide recovery equipment 10 of the first embodiment.

As shown in Figure 3, the reboiler heat transfer medium supply mechanism 50A may include a bypass pipe 85 that connects the heat storage unit heat transfer medium supply pipe 73 and the reboiler heat transfer medium supply pipe 60. The bypass pipe 85 can supply the heat storage unit heat transfer medium 74 from the heat storage unit heat transfer medium supply pipe 73 to the reboiler heat transfer medium supply pipe 60.

One end of the bypass pipe 85 is connected to the heat storage unit heat transfer medium supply pipe 73 upstream of the location where the flow control valve 73a is installed. The other end of the bypass pipe 85 is connected to the reboiler heat transfer medium supply pipe 60 on the reboiler 40 side of the location where it is connected to the connecting pipe 71.

The bypass pipe 85 is equipped with a flow control valve 85a. The reboiler heat transfer medium supply pipe 60, located on the reboiler 40 side of the point where it connects to the connecting pipe 71, is provided with a temperature detection unit 63 for detecting the temperature of the heat transfer medium supplied to the reboiler 40.

In other configurations of the reboiler heat transfer medium supply mechanism 50A, the reboiler heat transfer medium supply pipe 60 is supplied with, for example, a reboiler heat transfer medium 62 at a temperature exceeding the reboiler's allowable temperature.

In this configuration, the heat storage unit 81 may include a chemical heat storage material in addition to the latent heat storage material and sensible heat storage material mentioned above. Furthermore, as shown in Figure 3, when a bypass pipe 85 is provided, heat is stored at a temperature range exceeding the aforementioned operating temperature range (130 to 200°C), even when using the latent heat storage material and sensible heat storage material.

Chemical heat storage materials are heat storage materials that can achieve heat storage and release by utilizing the heat of chemical reactions generated when a reaction medium and a heat storage material come into contact. Chemical heat storage materials achieve heat storage and release by utilizing reversible endothermic and exothermic reactions. Examples of chemical heat storage materials include CaO/ _H₂O -based chemical heat storage materials and MgO/ _H₂O -based chemical heat storage materials. However, chemical heat storage materials are not limited to these examples; any chemical heat storage material that can achieve heat storage and release by utilizing reversible endothermic and exothermic reactions is acceptable.

When storing heat in a CaO/ _H₂O -based chemical heat storage material, heat is supplied to the heat storage material in the Ca(OH) _₂ state. In other words, the heat storage material in the Ca(OH) _₂ state is heated. Heat is stored through the dehydration reaction that occurs, in which Ca(OH) _₂ separates into CaO and _H₂O .

In this process, the heat storage material is heated to a temperature of 400-500°C. Heating the heat storage material to this temperature range promotes the dehydration reaction. In CaO/ _H₂O -based chemical heat storage materials, this temperature range is the set heating temperature.

On the other hand, when dissipating heat, water or steam is supplied to the heat storage material in the state of CaO. Heat is then released through the hydration reaction that occurs when the water or steam combines with the CaO.

When storing heat in a MgO/ _H₂O -based chemical heat storage material, heat is supplied to the heat storage material in the Mg(OH) _₂ state. In other words, the heat storage material in the Mg(OH) _₂ state is heated. Heat is stored through a dehydration reaction that separates the Mg(OH) _₂ into MgO and _H₂O .

In this process, the heat storage material is heated to a temperature of 200-400°C. Heating the heat storage material to this temperature range promotes the dehydration reaction. In MgO/ _H₂O -based chemical heat storage materials, this temperature range is the set heating temperature.

On the other hand, when dissipating heat, water or steam is supplied to the heat storage material in the MgO state. Heat is then released through the hydration reaction that occurs when the water or steam combines with the MgO.

Here, Figure 4 schematically shows the configuration of a heat storage device 80 equipped with a chemical heat storage material in a reboiler heat transfer medium supply mechanism 50A of the carbon dioxide recovery equipment 10 of the first embodiment, but with a different configuration. Here, examples are given of cases using CaO/ _H₂O system or MgO/ _H₂O system chemical heat storage materials that utilize dehydration and hydration reactions.

As shown in Figure 4, the heat storage unit 81, which is a container 88 filled with a chemical heat storage material 87, is housed within the device container 86 of the heat storage device 80. Heat exchange piping 84 is arranged in a meandering pattern within the heat storage unit 81. One end of the heat exchange piping 84 is connected to the communication piping 71. The other end of the heat exchange piping 84 is connected to the heat transfer medium discharge pipe 72 and the heat storage unit heat transfer medium supply pipe 73.

A water supply pipe 82 is connected to one side of the container 88 to supply water or steam to the heat storage unit 81. For example, a drain pipe 83 for discharging water from the heat storage unit 81 is connected to the other side of the container 88, opposite to the first side.

The water produced by the dehydration reaction described above is discharged to the outside through the drain pipe 83. The water or steam used in the hydration reaction described above is supplied through the water supply pipe 82.

When using a chemical heat storage material, heat can be released when needed, provided no chemical changes occur. In other words, the chemical heat storage material can maintain a heat storage state for extended periods. Furthermore, a cartridge containing a chemical heat storage material that has been heated by another heat source can be attached to the heat storage device 80 and used.

In the heat storage operation of the heat storage device 80 using a chemical heat storage material, a portion of the reboiler heat transfer medium 62 introduced into the heat exchange pipe 84 via the connecting pipe 71 heats the heat storage material in the state of Ca(OH) _₂ or Mg(OH) _₂ . The water produced by the dehydration reaction that occurs at this time is discharged from the drain pipe 83. No water is supplied from the water supply pipe 82 at this time.

Furthermore, when using chemical heat storage materials, the temperature of the reboiler heat transfer medium 62 introduced into the reboiler heat transfer medium supply pipe 60 is set to a temperature that causes a dehydration reaction in the chemical heat storage material. Therefore, the temperature of the reboiler heat transfer medium 62 introduced into the reboiler heat transfer medium supply pipe 60 exceeds the reboiler's allowable temperature.

Therefore, based on the temperature of the heat transfer medium supplied to the reboiler 40 detected by the temperature sensing unit 63, the flow rate control valve 85a of the bypass pipe 85 is adjusted. By adjusting the flow rate control valve 85a, the flow rate of the heat transfer medium 74 of the heat storage unit introduced into the reboiler heat transfer medium supply pipe 60 via the bypass pipe 85 is adjusted.

Then, the heat storage unit heat transfer medium 74, which is at a lower temperature than the reboiler heat transfer medium 62, is introduced into the reboiler heat transfer medium supply pipe 60 via the bypass pipe 85. As a result, the reboiler 40 is supplied with a mixed heat transfer medium, which is a mixture of the high-temperature reboiler heat transfer medium 62 and the low-temperature heat storage unit heat transfer medium 74. The temperature of this mixed heat transfer medium is adjusted to the reboiler's allowable temperature before being supplied to the reboiler 40.

In the process of storing heat in the heat storage unit 81, if the temperature of the reboiler heat transfer medium 62 detected by the temperature detection unit 76 is equal to the temperature of the reboiler heat transfer medium 62 introduced into the heat storage unit 81 via the communication pipe 71, the flow rate control valve 72a is closed. Specifically, for example, if the temperature of the reboiler heat transfer medium 62 detected by the temperature detection unit 76 is equal to the temperature of the reboiler heat transfer medium 62 detected by the temperature detection unit 75, the flow rate control valve 72a is closed. In this case, it means that the amount of heat stored in the heat storage unit 81 has exceeded the upper limit of heat storage capacity.

On the other hand, in the heat dissipation process of the heat storage device 80 using a chemical heat storage material, water or steam is supplied from the water supply pipe 82 to the heat storage material, which is in the state of CaO or MgO. This causes a hydration reaction, and the heat storage material dissipates heat.

Then, the heat storage fluid 74 introduced into the heat exchange piping 84 via the heat storage fluid supply pipe 73 is heated by the heat dissipation of the heat storage material. At this time, if the temperature of the heat storage fluid 74 introduced into the connecting pipe 71 is higher than the reboiler's allowable temperature, the flow control valve 85a of the bypass pipe 85 is adjusted based on the temperature of the heat storage fluid supplied to the reboiler 40 as detected by the temperature detection unit 63.

Then, a heat transfer medium 74 from the heat storage unit 81, at a temperature lower than that of the heat storage unit heat transfer medium 74 heated in the heat storage unit 81, is introduced into the reboiler heat transfer medium supply pipe 60 via the bypass pipe 85. As a result, the reboiler 40 is supplied with a mixed heat transfer medium, consisting of a mixture of the high-temperature heat storage unit heat transfer medium 74 and the low-temperature heat storage unit heat transfer medium 74. The temperature of this mixed heat transfer medium is adjusted to the reboiler's allowable temperature and supplied to the reboiler 40.

During the process of releasing heat from the heat storage unit 81, when the temperature of the heat storage unit's heat transfer medium 74, as detected by the temperature detection unit 75, falls below a lower threshold, the flow control valve 73a is closed, for example. When the temperature of the heat storage unit's heat transfer medium 74 discharged from the heat storage unit 81 falls below the lower threshold, it means that the amount of heat stored in the heat storage unit 81 has fallen below the lower heat storage limit. When the heat storage limit is exceeded, it means that the heat storage unit 81 does not have enough heat stored to heat the heat storage unit's heat transfer medium 74 to the reboiler's allowable temperature. The lower threshold during the release process is as described above.

During the process of releasing heat from the heat storage unit 81, if the temperature of the heat storage unit heat transfer medium 74 discharged from the heat storage unit 81 falls below a lower threshold and the flow rate control valve 73a is closed, the temperature of the reboiler heat transfer medium 62 supplied to the reboiler 40 is adjusted by the flow rate control valve 85a of the bypass pipe 85 based on the temperature detected by the temperature detection unit 63. Alternatively, when the flow rate control valve 73a is closed, the flow rate control valve 72a may be opened to switch to the heat storage process.

Although this explanation primarily uses the example of a case using a chemical heat storage material, the adjustment function of the flow control valve 85a based on the temperature detected by the temperature sensing unit 63 is the same when using the latent heat storage material or sensible heat storage material described above.

As described above, by providing the bypass pipe 85, even when the temperature of the reboiler heat transfer medium 62 supplied to the reboiler heat transfer medium supply pipe 60 exceeds the reboiler's allowable temperature, the reboiler 40 can still be supplied with heat transfer medium at the reboiler's allowable temperature. In other words, by providing the bypass pipe 85, it becomes possible to adjust the temperature of the reboiler heat transfer medium 62 supplied to the reboiler 40 based on the temperature of the heat transfer medium detected by the temperature detection unit 63.

(Second embodiment)
Figure 5 is a diagram of the reboiler heat transfer medium supply mechanism 50B in the carbon dioxide recovery equipment 11 of the second embodiment. In the following embodiments, the same reference numerals are used for components identical to those in the carbon dioxide recovery equipment 10 of the first embodiment, and redundant explanations are omitted or simplified.

In the second embodiment of the carbon dioxide recovery system 11, the configuration is the same as that of the first embodiment of the carbon dioxide recovery system 10, except for the reboiler heat transfer medium supply mechanism 50B. Therefore, this section will mainly describe the configuration of the reboiler heat transfer medium supply mechanism 50B.

The reboiler heat transfer medium supply mechanism 50B is configured to supply a heat transfer medium to the reboiler 40. As shown in Figure 5, the reboiler heat transfer medium supply mechanism 50B includes a heat storage device 80, a heating supply mechanism 70B, a reboiler heat transfer medium discharge pipe 61, and a bypass pipe 100.

The heat storage section 81 of the heat storage device 80 comprises a latent heat storage material, a sensible heat storage material, or a chemical heat storage material. The composition of each heat storage material is as described above.

The heating and supply mechanism 70B is configured to heat the heat storage section 81 of the heat storage device 80 and to supply the amount of heat stored in the heat storage section 81 to the reboiler 40. As shown in Figure 5, the heating and supply mechanism 70B includes a high-temperature heat transfer medium introduction pipe 90, a low-temperature heat transfer medium introduction pipe 91, a heat storage section heat transfer medium supply pipe 92, and a reboiler heat transfer medium supply pipe 93.

The high-temperature heat transfer medium introduction pipe 90 introduces a high-temperature heat transfer medium for supply to the reboiler 40. For example, steam (water vapor) generated in an external facility such as a plant is used as the high-temperature heat transfer medium. The temperature of the high-temperature heat transfer medium is higher than the reboiler's allowable temperature. Specifically, the temperature of the high-temperature heat transfer medium is, for example, a temperature at or above the temperature at which the heat storage material can be heated to its set temperature. That is, in the second embodiment, even when using latent heat storage material or sensible heat storage material, heat may be stored at a temperature range exceeding the aforementioned operating temperature range (130-200°C). The high-temperature heat transfer medium introduction pipe 90 functions as the first heat transfer medium introduction pipe.

The low-temperature heat transfer medium introduction pipe 91 introduces a low-temperature heat transfer medium at a lower temperature than the high-temperature heat transfer medium introduced into the high-temperature heat transfer medium introduction pipe 90. For example, steam (water vapor) generated in an external facility such as a plant is used as the low-temperature heat transfer medium. The temperature of the low-temperature heat transfer medium is lower than the reboiler's allowable temperature.

The low-temperature heat transfer medium introduction pipe 91 is connected to the high-temperature heat transfer medium introduction pipe 90. The low-temperature heat transfer medium introduction pipe 91 is equipped with a flow control valve 91a for adjusting the flow rate of the low-temperature heat transfer medium. The low-temperature heat transfer medium introduction pipe 91 also functions as a second heat transfer medium introduction pipe.

Here, the temperature of the low-temperature heat transfer medium is set to a temperature that can be adjusted to the reboiler's allowable temperature by mixing the high-temperature and low-temperature heat transfer mediums within a predetermined flow rate range. The predetermined flow rate range is the set flow rate range of the reboiler heat transfer medium 62 supplied to the reboiler 40.

The heat storage unit heat transfer medium supply pipe 92 supplies the heat transfer medium introduced through the high-temperature heat transfer medium introduction pipe 90 and the low-temperature heat transfer medium introduction pipe 91 to the heat storage unit 81 of the heat storage device 80. The heat storage unit heat transfer medium supply pipe 92 is located downstream from the connection point between the low-temperature heat transfer medium introduction pipe 91 and the heat storage unit heat transfer medium supply pipe 92, and is connected to the heat storage unit 81.

The heat storage unit's heat transfer medium supply pipe 92 supplies a high-temperature heat transfer medium, a low-temperature heat transfer medium, or a mixed heat transfer medium of the high-temperature and low-temperature heat transfer mediums to the heat storage unit 81. The heat storage unit's heat transfer medium supply pipe 92 is equipped with a flow control valve 92a for adjusting the flow rate of the heat transfer medium.

The reboiler heat transfer medium supply pipe 93 supplies the reboiler heat transfer medium 62 discharged from the heat storage unit 81 to the reboiler 40. The reboiler heat transfer medium discharged from the heat storage unit 81 is the heat transfer medium that was supplied to the heat storage unit 81 via the heat storage unit heat transfer medium supply pipe 92 and exchanged heat with the heat storage unit 81. The reboiler heat transfer medium supply pipe 93 supplies the reboiler heat transfer medium 62, which heats the absorbent liquid (lean liquid 32) in the reboiler 40, to the reboiler 40. The reboiler heat transfer medium supply pipe 93 is installed between the heat storage unit 81 and the reboiler 40.

Furthermore, the reboiler heat transfer medium supply pipe 93 is equipped with a temperature detection unit 94 for detecting the temperature of the heat transfer medium supplied to the reboiler 40. The temperature detection unit 94 is located on the reboiler heat transfer medium supply pipe 93 on the side of the reboiler 40 that connects to the bypass pipe 100.

Furthermore, the reboiler heat transfer medium supply pipe 93 is equipped with a temperature detection unit 95 for detecting the temperature of the heat transfer medium discharged from the heat storage unit 81. The temperature detection unit 95 is located on the side of the reboiler heat transfer medium supply pipe 93 closer to the heat storage device 80 than the connection point that connects to the bypass pipe 100.

The reboiler heat transfer medium discharge pipe 61 of the reboiler heat transfer medium supply mechanism 50B has the same configuration as in the first embodiment.

The bypass pipe 100 supplies the heat transfer medium from the heat storage unit heat transfer medium supply pipe 92 to the reboiler heat transfer medium supply pipe 93. The bypass pipe 100 is configured to bypass the heat storage device 80 and connect the heat storage unit heat transfer medium supply pipe 92 and the reboiler heat transfer medium supply pipe 93. The bypass pipe 100 includes a flow control valve 100a for adjusting the flow rate of the heat transfer medium.

Next, the operation of the reboiler heat transfer medium supply mechanism 50B will be explained.

Here, at the start of operation, it is preferable that the heat storage section 81 of the heat storage device 80 has a predetermined amount of heat stored in the heat storage material. Hereinafter, this state will be referred to as the initial state.

In the case of latent heat storage materials, the initial state can be exemplified by, for example, the state in which the latent heat storage material has reached its melting point. Another example of an initial state is a state in which the solid phase and liquid phase are mixed.

In the case of sensible heat storage materials, the initial state is exemplified by the state in which the sensible heat storage material has been heated to, for example, the allowable temperature of the reboiler.

In the case of chemical heat storage materials, the initial state is exemplified by a state in which the chemical heat storage material has stored heat through a dehydration reaction and the chemical heat storage material has released heat through a hydration reaction are mixed in equal amounts. For example, in CaO/ _H₂O -based chemical heat storage materials, an example is a state in which Ca(OH) _₂ and CaO are mixed in equal amounts. For MgO/ _H₂O -based chemical heat storage materials, an example is a state in which Mg(OH) _₂ and MgO are mixed in equal amounts.

By setting the heat storage unit 81 to the initial state described above, both heat storage and heat dissipation processes can be performed.

Here, we will explain the process of bringing a latent heat storage material or a sensible heat storage material from a state where no heat is stored to its initial state.

The flow rate control valve 91a is adjusted to control the flow rate of the low-temperature heat transfer medium flowing through the heat storage unit's heat transfer medium supply pipe 92. Then, in the heat storage unit's heat transfer medium supply pipe 92, the temperature of the mixed heat transfer medium (high-temperature heat transfer medium and low-temperature heat transfer medium) introduced from the high-temperature heat transfer medium introduction pipe 90 is adjusted to a predetermined temperature. The temperature of the mixed heat transfer medium is adjusted to, for example, a temperature higher than the reboiler's allowable temperature.

A portion of the mixed heat transfer medium is supplied to the heat storage unit 81 from the heat storage unit heat transfer medium supply pipe 92. The heat storage unit 81 is heated by the supplied mixed heat transfer medium and stores heat. The mixed heat transfer medium from which heat has been absorbed by the heat storage unit 81 is discharged from the heat storage unit 81 and introduced into the reboiler heat transfer medium supply pipe 93. At this point, the temperature of the mixed heat transfer medium is lower than the reboiler's allowable temperature.

The remaining mixed heat transfer medium is introduced into the reboiler heat transfer medium supply pipe 93 via the bypass pipe 100.

The mixed heat transfer medium discharged from the heat storage unit 81 and the mixed heat transfer medium introduced via the bypass pipe 100 are mixed in the reboiler heat transfer medium supply pipe 93 and supplied to the reboiler 40 as the reboiler heat transfer medium 62. Here, the flow control valves 92a and 100a adjust the temperature of the reboiler heat transfer medium 62 to the reboiler's allowable temperature based on the temperature of the heat transfer medium detected by the temperature detection unit 94.

Then, based on the temperature of the heat transfer medium detected by the temperature detection unit 95, when it is determined that the temperature of the mixed heat transfer medium discharged from the heat storage unit 81 has reached a predetermined temperature, the operation to return to the initial state is stopped.

Furthermore, as a predetermined temperature for stopping the process to return to the initial state, examples include the melting point temperature for latent heat storage materials and the reboiler's allowable temperature for sensible heat storage materials.

Through this process, the latent heat storage material or sensible heat storage material in the heat storage unit 81 returns to its initial state. From this initial state, a heat storage treatment or heat dissipation treatment is then performed.

Next, the operation of the heat storage device 80 during heat storage will be explained.

Here, the heat storage function will be explained separately for two cases: when a heat transfer medium at the reboiler's allowable temperature is introduced into the heat storage unit 81, and when a heat transfer medium at a temperature exceeding the reboiler's allowable temperature is introduced into the heat storage unit 81.

First, we will explain the case where a heat transfer medium with a reboiler-permissible temperature is introduced into the heat storage unit 81.

During heat storage, the flow control valve 100a is closed. That is, the mixed heat transfer medium from the heat storage unit's heat transfer medium supply pipe 92 does not flow through the bypass pipe 100.

During heat storage, the flow rate of the low-temperature heat transfer medium introduced from the low-temperature heat transfer medium introduction pipe 91 to the heat storage section heat transfer medium supply pipe 92 is controlled by the flow rate control valve 91a. For example, the flow rate of the low-temperature heat transfer medium introduced from the low-temperature heat transfer medium introduction pipe 91 to the heat storage section heat transfer medium supply pipe 92 is adjusted to be less than the flow rate of the high-temperature heat transfer medium introduced from the high-temperature heat transfer medium introduction pipe 90 to the heat storage section heat transfer medium supply pipe 92. Specifically, the flow rate control valve 91a is adjusted so that the temperature of the heat transfer medium supplied from the heat storage section heat transfer medium supply pipe 92 to the heat storage section 81 reaches the reboiler's allowable temperature. In this case, the temperature of the heat transfer medium supplied from the heat storage section heat transfer medium supply pipe 92 to the heat storage section 81 corresponds to the set heating temperature of the heat storage material in the heat storage section 81.

Furthermore, if the temperature of the high-temperature heat transfer medium from the high-temperature heat transfer medium introduction pipe 90 is within the reboiler's allowable temperature, all the heat transfer medium introduced into the heat storage section's heat transfer medium supply pipe 92 may be the high-temperature heat transfer medium from the high-temperature heat transfer medium introduction pipe 90. In this case, the flow control valve 91a is closed.

Here, an example of a situation in which heat storage treatment is performed is when excess high-temperature heat transfer fluid is generated during high-load operation in a plant, for instance.

The heat transfer medium (mixed heat transfer medium) supplied to the heat storage unit 81 via the heat transfer medium supply pipe 92 heat storage unit heats the heat storage material. As a result, the heat storage material stores heat. The heat transfer medium (mixed heat transfer medium) discharged from the heat storage unit 81 is supplied to the reboiler 40 via the reboiler heat transfer medium supply pipe 93 as the reboiler heat transfer medium 62. Since the heat storage unit 81 is in its initial state before entering the heat storage process, the temperature of the heat transfer medium (mixed heat transfer medium) discharged from the heat storage unit 81 is at the reboiler's allowable temperature. Furthermore, the flow rate of the heat transfer medium (mixed heat transfer medium) introduced into the reboiler heat transfer medium supply pipe 93 is adjusted to the set flow rate of the reboiler 40.

In the process of storing heat in the heat storage unit 81, if the temperature of the heat transfer medium (mixed heat transfer medium) detected by the temperature detection unit 95 is equal to the temperature of the heat transfer medium (mixed heat transfer medium) introduced into the heat storage unit 81 via the heat storage unit heat transfer medium supply pipe 92, then, for example, the flow rate control valve 92a is closed and the flow rate control valve 100a is opened. In this case, it means that the amount of heat stored in the heat storage unit 81 has exceeded the upper limit of heat storage capacity.

Then, the heat transfer medium (mixed heat transfer medium) is introduced into the reboiler heat transfer medium supply pipe 93 via the bypass pipe 100. At this time, the flow control valve 91a adjusts the temperature of the reboiler heat transfer medium 62 to the reboiler's allowable temperature based on the temperature of the heat transfer medium detected by the temperature detection unit 94. Furthermore, the flow control valve 100a adjusts the flow rate of the heat transfer medium (mixed heat transfer medium) introduced into the reboiler heat transfer medium supply pipe 93 to the set flow rate of the reboiler 40.

Next, we will explain the case where a heat transfer medium with a temperature exceeding the reboiler's allowable temperature is introduced into the heat storage unit 81.

During heat storage, the flow rate of the low-temperature heat transfer medium introduced from the low-temperature heat transfer medium introduction pipe 91 to the heat storage section heat transfer medium supply pipe 92 is controlled by the flow rate control valve 91a. For example, the flow rate of the low-temperature heat transfer medium introduced from the low-temperature heat transfer medium introduction pipe 91 to the heat storage section heat transfer medium supply pipe 92 is adjusted to be less than the flow rate of the high-temperature heat transfer medium introduced from the high-temperature heat transfer medium introduction pipe 90 to the heat storage section heat transfer medium supply pipe 92. Specifically, the flow rate control valve 91a is adjusted so that the temperature of the heat transfer medium supplied from the heat storage section heat transfer medium supply pipe 92 to the heat storage section 81 is higher than the reboiler's allowable temperature.

Furthermore, when storing heat, all the heat transfer medium introduced into the heat transfer medium supply pipe 92 of the heat storage unit may be the high-temperature heat transfer medium from the high-temperature heat transfer medium introduction pipe 90. In this case, the flow control valve 91a is closed.

Here, when introducing a heat transfer medium at a temperature exceeding the reboiler's allowable temperature into the heat storage unit 81, the heat transfer medium (mixed heat transfer medium) is introduced into the reboiler heat transfer medium supply pipe 93 via the bypass pipe 100, and the temperature of the reboiler heat transfer medium 62 is adjusted to the reboiler's allowable temperature.

Specifically, the flow control valve 91a adjusts the temperature of the reboiler heat transfer medium 62 to the reboiler's allowable temperature based on the temperature of the heat transfer medium detected by the temperature sensing unit 94. Furthermore, the flow control valves 92a and 100a adjust the flow rate of the heat transfer medium (mixed heat transfer medium) supplied to the reboiler 40 to the set flow rate of the reboiler 40.

The heat transfer medium (mixed heat transfer medium) supplied to the heat storage unit 81 via the heat transfer medium supply pipe 92 heat storage unit heats the heat storage material. As a result, the heat storage material stores heat. The heat transfer medium (mixed heat transfer medium) discharged from the heat storage unit 81 mixes with the heat transfer medium (mixed heat transfer medium) introduced via the bypass pipe 100 and is supplied to the reboiler 40 via the reboiler heat transfer medium supply pipe 93 as the reboiler heat transfer medium 62.

In the process of storing heat in the heat storage unit 81, if the temperature of the heat transfer medium (mixed heat transfer medium) detected by the temperature detection unit 95 is equal to the temperature of the heat transfer medium (mixed heat transfer medium) introduced into the heat storage unit 81 via the heat storage unit heat transfer medium supply pipe 92, for example, the flow rate control valve 92a is closed. In this case, it means that the amount of heat stored in the heat storage unit 81 has exceeded the upper limit of heat storage capacity. The temperature of the heat transfer medium (mixed heat transfer medium) introduced into the heat storage unit 81 is detected by a temperature detection unit (not shown) provided in the heat storage unit heat transfer medium supply pipe 92.

When the flow control valve 92a is closed, the flow control valve 91a adjusts the temperature of the heat transfer medium (mixed heat transfer medium) introduced into the reboiler heat transfer medium supply pipe 93 via the bypass pipe 100 to the reboiler's allowable temperature, based on the temperature of the heat transfer medium detected by the temperature detection unit 94. Furthermore, the flow control valve 100a adjusts the flow rate of the heat transfer medium (mixed heat transfer medium) introduced into the reboiler heat transfer medium supply pipe 93 to match the set flow rate of the reboiler 40.

Next, the process of heat dissipation in the heat storage device 80 will be explained.

Here, the heat dissipation process will be explained separately for two cases: when the heat transfer medium (mixed heat transfer medium) in the heat storage unit 81 is heated to the reboiler's allowable temperature, and when the heat transfer medium (mixed heat transfer medium) in the heat storage unit 81 is heated to a temperature exceeding the reboiler's allowable temperature.

First, we will explain the case where the heat transfer medium (mixed heat transfer medium) in the heat storage unit 81 is heated to the reboiler's allowable temperature.

During heat dissipation, the flow control valve 100a is closed. That is, the mixed heat transfer medium from the heat storage unit's heat transfer medium supply pipe 92 does not flow through the bypass pipe 100.

During heat dissipation, the flow control valve 91a is adjusted so that the flow rate of the low-temperature heat transfer medium introduced from the low-temperature heat transfer medium introduction pipe 91 to the heat storage section heat transfer medium supply pipe 92 is greater than the flow rate of the high-temperature heat transfer medium introduced from the high-temperature heat transfer medium introduction pipe 90 to the heat storage section heat transfer medium supply pipe 92. Specifically, the flow control valve 91a is adjusted so that the temperature of the heat transfer medium supplied from the heat storage section heat transfer medium supply pipe 92 to the heat storage section 81 is lower than the reboiler's allowable temperature.

Furthermore, when dissipating heat, all the heat transfer medium introduced into the heat storage unit's heat transfer medium supply pipe 92 may be the low-temperature heat transfer medium from the low-temperature heat transfer medium introduction pipe 91. In this case, the flow control valve (not shown) provided in the high-temperature heat transfer medium introduction pipe 90 is closed.

Here, an example of a situation where heat dissipation is performed is when a plant operates under low load, causing the temperature of the introduced heat transfer medium to decrease.

The heat transfer medium (mixed heat transfer medium) supplied to the heat storage unit 81 via the heat transfer medium supply pipe 92 absorbs heat from the heat storage material. This heats the heat transfer medium (mixed heat transfer medium) to the reboiler's allowable temperature. The heat transfer medium (mixed heat transfer medium) discharged from the heat storage unit 81 is supplied to the reboiler 40 as the reboiler heat transfer medium 62 via the reboiler heat transfer medium supply pipe 93.

In the process of releasing heat from the heat storage unit 81, when the temperature of the reboiler heat transfer medium 62, as detected by the temperature detection unit 95, falls below the lower threshold, the flow rate control valve 92a is closed and the flow rate control valve 100a is opened. The flow rate control valve 91a is also adjusted.

When the temperature of the heat transfer medium 74 discharged from the heat storage unit 81 falls below the lower threshold, it means that the amount of heat stored in the heat storage unit 81 has fallen below the lower limit of heat storage. The lower threshold during the heat dissipation process is as described above.

In this case, the flow control valve 91a is adjusted to adjust the temperature of the mixed heat medium in the heat storage unit's heat medium supply pipe 92 to the reboiler's allowable temperature. The mixed heat medium, adjusted to the reboiler's allowable temperature, is then introduced into the reboiler heat medium supply pipe 93 via the bypass pipe 100. This mixed heat medium is then supplied to the reboiler 40 as the reboiler heat medium 62. The flow control valve 100a adjusts the flow rate of the heat medium (mixed heat medium) introduced into the reboiler heat medium supply pipe 93 to match the set flow rate of the reboiler 40.

Next, we will explain the case where the heat transfer medium (mixed heat transfer medium) in the heat storage unit 81 is heated to a temperature exceeding the reboiler's allowable temperature.

In this case, the flow control valve 100a is open. Then, the heat transfer medium (mixed heat transfer medium) is introduced from the heat storage unit heat transfer medium supply pipe 92 to the reboiler heat transfer medium supply pipe 93 via the bypass pipe 100. Furthermore, if a chemical heat storage material is used as the heat storage material, water or steam is supplied from the water supply pipe 82 to the heat storage unit 81 when heat is released.

During heat dissipation, the flow control valve 91a is adjusted so that the flow rate of the low-temperature heat transfer medium introduced from the low-temperature heat transfer medium introduction pipe 91 to the heat storage section heat transfer medium supply pipe 92 is greater than the flow rate of the high-temperature heat transfer medium introduced from the high-temperature heat transfer medium introduction pipe 90 to the heat storage section heat transfer medium supply pipe 92. In other words, the temperature of the heat transfer medium supplied from the heat storage section heat transfer medium supply pipe 92 to the heat storage section 81 is set lower than, for example, the reboiler's allowable temperature.

Furthermore, when dissipating heat, all the heat transfer medium introduced into the heat storage unit's heat transfer medium supply pipe 92 may be the low-temperature heat transfer medium from the low-temperature heat transfer medium introduction pipe 91. In this case, the flow control valve (not shown) provided in the high-temperature heat transfer medium introduction pipe 90 is closed.

The heat transfer medium (mixed heat transfer medium) supplied to the heat storage unit 81 via the heat transfer medium supply pipe 92 absorbs heat from the heat storage material. This heats the heat transfer medium (mixed heat transfer medium). The heat transfer medium (mixed heat transfer medium) discharged from the heat storage unit 81 mixes with the heat transfer medium (mixed heat transfer medium) introduced via the bypass pipe 100 and is supplied to the reboiler 40 via the reboiler heat transfer medium supply pipe 93 as the reboiler heat transfer medium 62.

In this process of releasing heat from the heat storage unit 81, the flow control valve 91a adjusts the temperature of the reboiler heat transfer medium 62 to the reboiler's allowable temperature, based on the temperature of the heat transfer medium detected by the temperature detection unit 94. Specifically, the flow control valve 91a adjusts the temperature of the heat transfer medium (mixed heat transfer medium) introduced into the reboiler heat transfer medium supply pipe 93 via the bypass pipe 100 so that the temperature of the reboiler heat transfer medium 62 reaches the reboiler's allowable temperature.

Furthermore, during the process of releasing heat from the heat storage unit 81, the flow control valve 92a is closed when the temperature of the reboiler heat transfer medium 62, as detected by the temperature detection unit 95, falls below a lower threshold. The predetermined threshold during the heat dissipation process is as described above.

Then, by adjusting the flow control valve 91a, the temperature of the mixed heat medium in the heat storage unit's heat medium supply pipe 92 is adjusted to the reboiler's allowable temperature. Furthermore, the flow control valve 100a adjusts the flow rate of the heat medium (mixed heat medium) introduced into the reboiler's heat medium supply pipe 93 so that it matches the set flow rate of the reboiler 40.

According to the carbon dioxide recovery equipment 11 of the second embodiment described above, when excess high-temperature heat transfer medium is generated in a plant or other source of heat transfer medium due to high-load operation, the heat storage device 80 can store the amount of heat contained in the excess heat transfer medium.

Furthermore, even if the temperature of the heat transfer medium decreases due to low-load operation of a plant or other equipment, the heat stored in the heat storage device 80 can be used to supply the reboiler heat transfer medium 62 at the appropriate temperature to the reboiler 40.

Furthermore, by providing a high-temperature heat transfer medium introduction pipe 90 and a low-temperature heat transfer medium introduction pipe 91, a heat transfer medium at the appropriate temperature can be supplied to the heat storage unit 81. Also, even when the heat transfer in the heat storage unit 81 is interrupted, the bypass pipe 100 allows the reboiler heat transfer medium at the optimal temperature and flow rate to be supplied to the reboiler 40.

Thus, the carbon dioxide capture system 11 can effectively utilize the surplus heat generated by external facilities such as plants in the reboiler 40. Furthermore, even if load fluctuations occur in the plant or other heat transfer medium supply source, the reboiler 40 can properly heat the absorbent liquid.

Here, the configuration of the heat storage unit 81 of the heat storage device 80 is not limited to the configuration described above.

Figures 6 and 7 schematically show the configuration of a different heat storage device 80 in the carbon dioxide capture system 11 of the second embodiment.

First, we will explain the heat storage device 80 shown in Figure 6.

As shown in Figure 6, the heat storage device 80 may comprise a heat storage section 81A equipped with a chemical heat storage material and a heat storage section 81B equipped with a latent heat storage material or a sensible heat storage material. The heat storage section 81A is located on the heat storage section heat transfer medium supply pipe 92 side, and the heat storage section 81B is located on the reboiler heat transfer medium supply pipe 93 side. That is, the heat storage section 81A is located upstream of the flow of the heat transfer medium (mixed heat transfer medium), and the heat storage section 81B is located downstream.

The heat storage unit 81A, equipped with a chemical heat storage material, includes a water supply pipe 82 and a drain pipe 83. The heat storage unit 81A is connected to the heat storage unit heat transfer medium supply pipe 92. The heat storage unit 81B is connected to the reboiler heat transfer medium supply pipe 93. The heat storage units 81A and 81B are connected by a connecting pipe 110.

First, we will explain the process of heat storage in the heat storage device 80.

In the heat storage device 80 shown in Figure 6, when heat is stored in the heat storage device 80, a heat transfer medium (mixed heat transfer medium) is supplied to the heat storage section 81A via the heat transfer medium supply pipe 92. As mentioned above, the heat transfer medium (mixed heat transfer medium) is introduced into the heat exchange piping 84 within the heat storage section 81A (see Figure 4).

Furthermore, the temperature of the heat transfer medium supplied from the heat transfer medium supply pipe 92 to the heat transfer unit 81A is set higher than, for example, the allowable temperature of the reboiler. Specifically, the temperature of the heat transfer medium supplied from the heat transfer medium supply pipe 92 to the heat transfer unit 81A is set to correspond to the set heating temperature of the heat storage material in the heat transfer unit 81.

In the heat storage section 81A, which is equipped with a chemical heat storage material, a dehydration reaction occurs in the chemical heat storage material. That is, the heat transfer medium (mixed heat transfer medium) supplied to the heat storage section 81A heats the chemical heat storage material, causing a dehydration reaction. The water produced by the dehydration reaction is discharged through the drain pipe 83.

The heat transfer medium (mixed heat transfer medium) used to heat the chemical heat storage material is introduced into the heat storage section 81B via the connecting pipe 110. The heat transfer medium (mixed heat transfer medium) introduced into the heat storage section 81B transfers heat to the heat storage material in the heat storage section 81B. As a result, the heat storage material in the heat storage section 81B stores heat. The heat transfer medium (mixed heat transfer medium) that has transferred heat to the heat storage material in the heat storage section 81B is then introduced into the reboiler heat transfer medium supply pipe 93. The subsequent operation is as described above.

Next, the process of heat dissipation in the heat storage device 80 will be explained.

In the heat storage device 80 shown in Figure 6, when heat is released from the heat storage device 80, a heat transfer medium (mixed heat transfer medium) is supplied to the heat storage section 81A via the heat transfer medium supply pipe 92.

Furthermore, the temperature of the heat transfer medium supplied from the heat transfer medium supply pipe 92 to the heat transfer unit 81A is set lower than, for example, the allowable temperature of the reboiler.

In the heat storage section 81A, which is equipped with a chemical heat storage material, the aforementioned hydration reaction occurs in the chemical heat storage material. Specifically, water or steam is supplied from the water supply pipe 82 to the heat storage section 81A, and heat is released from the chemical heat storage material through the hydration reaction. This heat release heats the heat transfer medium (mixed heat transfer medium) flowing through the heat exchange piping 84.

The heated heat transfer medium (mixed heat transfer medium) is introduced into the heat storage unit 81B through the connecting pipe 110. The heat transfer medium (mixed heat transfer medium) introduced into the heat storage unit 81B absorbs heat from the heat storage material in the heat storage unit 81B and is further heated. The heated heat transfer medium (mixed heat transfer medium) is then introduced into the reboiler heat transfer medium supply pipe 93. The subsequent operation is as described above.

According to the heat storage device 80 described above, by providing a heat storage section 81A of a chemical heat storage material on the upstream side, for example, when setting the heat storage section 81B to its initial state, it is possible to supply steam at an appropriate temperature to the heat storage section 81B by utilizing the hydration reaction of the heat storage section 81A without adjusting the temperature of the mixed heat transfer medium.

Furthermore, by providing a latent heat storage material or a sensible heat storage material on the downstream side, even if a high-temperature heat transfer medium is discharged from the heat storage section 81A during the heat storage process, the amount of heat contained in the high-temperature heat transfer medium can be stored in the heat storage section 81B.

Next, we will explain the heat storage device 80 shown in Figure 7.

As shown in Figure 7, the heat storage device 80 may comprise a heat storage section 81C equipped with a sensible heat storage material and a heat storage section 81D equipped with a latent heat storage material. The heat storage section 81C is located on the heat storage section heat transfer medium supply pipe 92 side, and the heat storage section 81D is located on the reboiler heat transfer medium supply pipe 93 side. That is, the heat storage section 81C is located upstream of the flow of the heat transfer medium (mixed heat transfer medium), and the heat storage section 81D is located downstream.

The heat storage unit 81C is connected to the heat storage unit heat transfer medium supply pipe 92. The heat storage unit 81D is connected to the reboiler heat transfer medium supply pipe 93. The heat storage unit 81C and the heat storage unit 81D are connected by a connecting pipe 111.

First, we will explain the process of heat storage in the heat storage device 80.

In the heat storage device 80 shown in Figure 7, when heat is stored in the heat storage device 80, a heat transfer medium (mixed heat transfer medium) is supplied to the heat storage section 81C via the heat transfer medium supply pipe 92. The temperature of the heat transfer medium supplied from the heat transfer medium supply pipe 92 to the heat storage section 81C is set higher than, for example, the allowable temperature of the reboiler. Specifically, the temperature of the heat transfer medium supplied from the heat transfer medium supply pipe 92 to the heat storage section 81C is set to correspond to the set heating temperature of the heat storage material in the heat storage section 81C.

The heat transfer medium (mixed heat transfer medium) supplied to the heat storage unit 81C transfers heat to the sensible heat storage material in the heat storage unit 81C. As a result, the sensible heat storage material in the heat storage unit 81C stores heat.

The heat transfer medium (mixed heat transfer medium) that has heated the sensible heat storage material is introduced into the heat storage section 81D through the connecting pipe 111. The heat transfer medium (mixed heat transfer medium) introduced into the heat storage section 81D transfers heat to the latent heat storage material in the heat storage section 81D. As a result, the latent heat storage material in the heat storage section 81D stores heat. The heat transfer medium (mixed heat transfer medium) that has transferred heat to the latent heat storage material in the heat storage section 81D is then introduced into the reboiler heat transfer medium supply pipe 93. The subsequent operation is as described above.

Next, the process of heat dissipation in the heat storage device 80 will be explained.

In the heat storage device 80 shown in Figure 7, when heat is released from the heat storage device 80, a heat transfer medium (mixed heat transfer medium) is supplied to the heat storage unit 81C via the heat transfer medium supply pipe 92. The temperature of the heat transfer medium supplied from the heat transfer medium supply pipe 92 to the heat storage unit 81C is set lower than, for example, the allowable temperature of the reboiler.

The heat transfer medium (mixed heat transfer medium) supplied to the heat storage unit 81C absorbs heat from the sensible heat storage material in the heat storage unit 81C and is heated.

The heated heat transfer medium (mixed heat transfer medium) is introduced into the heat storage unit 81D through the connecting pipe 111. The heat transfer medium (mixed heat transfer medium) introduced into the heat storage unit 81D absorbs heat from the sensible heat storage material in the heat storage unit 81D and is further heated. The heated heat transfer medium (mixed heat transfer medium) is then introduced into the reboiler heat transfer medium supply pipe 93. The subsequent operation is as described above.

According to the heat storage device 80 described above, by providing a heat storage section 81D of latent heat storage material on the downstream side, even if, for example, the outlet temperature of the heat storage section 81C is higher than the melting point of the latent heat storage material in the heat storage section 81D, a heat transfer medium (mixed heat transfer medium) at the reboiler's allowable temperature can be introduced into the reboiler heat transfer medium supply pipe 93.

Furthermore, by providing a latent heat storage section 81D on the downstream side, the sensible heat storage material in the heat storage section 81C can be heated with a high-temperature heat transfer medium (mixed heat transfer medium) exceeding the reboiler's allowable temperature. This increases the amount of heat that can be stored in the heat storage section 81C compared to cases where the heat storage section 81C and heat storage section 81D are composed solely of sensible heat storage material or solely of latent heat storage material.

(Third embodiment)
Figure 8 is a diagram of the reboiler heat transfer medium supply mechanism 50C in the carbon dioxide recovery equipment 12 of the third embodiment.

In the third embodiment of the carbon dioxide recovery system 12, the configuration is the same as that of the first embodiment of the carbon dioxide recovery system 10, except for the reboiler heat transfer medium supply mechanism 50C. Therefore, this section will mainly describe the configuration of the reboiler heat transfer medium supply mechanism 50C.

The reboiler heat transfer medium supply mechanism 50C is configured to supply a heat transfer medium to the reboiler 40. As shown in Figure 8, the reboiler heat transfer medium supply mechanism 50C includes a heat storage device 80 and a heating supply mechanism 70C.

The heat storage section 81 of the heat storage device 80 is composed of either a latent heat storage material or a sensible heat storage material. Alternatively, as shown in Figure 7, the heat storage device 80 may be configured to include a heat storage section 81C equipped with a sensible heat storage material and a heat storage section 81D equipped with a latent heat storage material. The composition of each heat storage material is as described above.

The heating and supply mechanism 70C is configured to heat the heat storage section 81 of the heat storage device 80 and to supply the amount of heat stored in the heat storage section 81 to the reboiler 40. As shown in Figure 8, the heating and supply mechanism 70C includes a heat storage section heat transfer medium supply pipe 120, a heat storage section heat transfer medium discharge pipe 121, a heat exchange pipe 124, and a circulation pipe 130.

The heat storage unit heat transfer medium supply pipe 120 supplies the heat storage unit heat transfer medium 123 to the heat storage unit 81 of the heat storage device 80. As the heat storage unit heat transfer medium 123, for example, steam (water vapor) generated in a thermal power plant, steel mill, or waste treatment plant equipped with a carbon dioxide recovery facility 12 is used.

The heat storage unit heat transfer fluid discharge pipe 121 discharges the heat storage unit heat transfer fluid 123 supplied from the heat storage unit heat transfer fluid supply pipe 120 from the heat storage unit 81. For example, if the carbon dioxide recovery equipment 12 is installed in a thermal power plant equipped with a steam turbine, the heat storage unit heat transfer fluid 123 that condenses into water in the heat storage unit 81 is introduced into the feedwater pipe between the condenser and the boiler via the heat storage unit heat transfer fluid discharge pipe 121.

The heat storage unit's heat transfer medium discharge pipe 121 is equipped with a temperature detection unit 125 that detects the temperature of the heat storage unit's heat transfer medium 123 discharged from the heat storage unit 81 (heat exchange piping 124). The temperature detection unit 125 is located on the heat storage unit's heat transfer medium discharge pipe 121 on the heat storage device 80 side.

Within the heat storage unit 81, for example, heat exchange piping 124 is arranged in a meandering manner. One end of the heat exchange piping 124 is connected to the heat storage unit's heat transfer medium supply pipe 120. The other end of the heat exchange piping 124 is connected to the heat storage unit's heat transfer medium discharge pipe 121.

The circulation piping 130 circulates the circulating heat transfer medium 131 to the heat storage unit 81 and the reboiler 40. The circulation piping 130 includes a supply circulation piping 130A that supplies the circulating heat transfer medium 131 from the heat storage unit 80 to the reboiler 40, and a return circulation piping 130B that returns the circulating heat transfer medium 131 from the reboiler 40 to the heat storage unit 80.

Furthermore, the circulation piping 130 includes, for example, a circulation pump 132 for circulating the circulating heat transfer medium 131. Here, an example is shown where the circulation pump 132 is provided in the return circulation piping 130B. Note that the circulation pump 132 may also be provided in the supply circulation piping 130A.

The supply circulation pipe 130A is equipped with a temperature detection unit 133 that detects the temperature of the circulating heat transfer medium 131 discharged from the heat storage unit 81. The temperature detection unit 133 is located on the supply circulation pipe 130A on the heat storage device 80 side.

Here, the circulating heat transfer medium 131 can be, for example, air, steam, pressurized water, oil, molten salt, or inorganic hydrate. Thus, the circulating heat transfer medium 131 may be composed of a different substance than, for example, the heat transfer medium 123 of the heat storage unit. Alternatively, the circulating heat transfer medium 131 may be composed of the same substance as the heat transfer medium 123 of the heat storage unit.

Next, the operation of the reboiler heat transfer medium supply mechanism 50C will be explained.

Here, at the start of operation, it is preferable that the heat storage section 81 of the heat storage device 80 is in the initial state described above.

Furthermore, in the reboiler heat transfer medium supply mechanism 50C, the heat storage function in the heat storage device 80 and the supply function of the circulating heat transfer medium 131 to the reboiler 40 can be performed independently.

First, we will explain the process of heat storage in the heat storage device 80.

During heat storage, the heat storage unit heat transfer medium 123 is supplied from the heat storage unit heat transfer medium supply pipe 120 to the heat storage unit 81 (heat exchange piping 124). The temperature of the heat storage unit heat transfer medium 123 supplied from the heat storage unit heat transfer medium supply pipe 120 to the heat storage unit 81 is set, for example, to the reboiler's allowable temperature. The temperature of the heat storage unit heat transfer medium 123 is set to correspond to the set heating temperature of the heat storage material in the heat storage unit 81.

The heat storage fluid 123 supplied to the heat storage unit 81 (heat exchange piping 124) via the heat storage unit heat fluid supply pipe 120 heat storage unit heat fluid heats the heat storage material. As a result, the heat storage material stores heat. The heat storage unit heat fluid 123, from which heat has been absorbed by the heat storage unit 81, is discharged from the heat exchange piping 124 to the heat storage unit heat fluid discharge pipe 121.

Here, when the temperature detection unit 125 detects that the temperature of the heat storage fluid 123 discharged from the heat storage unit 81 is equal to the temperature of the heat storage fluid 123 supplied to the heat storage unit 81, it means that the amount of heat stored in the heat storage unit 81 has exceeded the upper limit of heat storage. In this case, for example, the supply of the heat storage fluid 123 to the heat exchange piping 124 is stopped.

Next, the process of heat dissipation in the heat storage device 80 will be explained.

The circulating heat transfer medium 131, introduced into the heat storage unit 81 from the return circulation pipe 130B, absorbs heat from the heat storage material. This heats the circulating heat transfer medium 131 to the reboiler's allowable temperature. The heated circulating heat transfer medium 131 is then discharged from the heat storage unit 81 and supplied to the reboiler 40 via the supply circulation pipe 130A.

The circulating heat transfer medium 131, which has heated the lean liquid 32 in the reboiler 40, is circulated again to the heat storage unit 81 via the return circulation pipe 130B.

Here, if the temperature detection unit 133 detects that the temperature of the circulating heat medium 131 discharged from the heat storage unit 81 has fallen below the lower threshold, it means that the amount of heat stored in the heat storage unit 81 has fallen below the lower limit of heat storage. The lower threshold during the heat dissipation process is as described above. In this case, the circulation pump 132 is stopped, and the supply of the circulating heat medium 131 to the heat storage unit 81 is stopped.

When performing both heat storage and heat dissipation operations, if the temperature of the circulating heat medium 131 discharged from the heat storage unit 81 falls below the lower threshold, the circulation pump 132 is stopped, as described above, and the supply of the circulating heat medium 131 to the heat storage unit 81 is stopped.

Furthermore, when performing both heat storage and heat dissipation simultaneously, it is preferable that the amount of heat stored in the heat storage unit 81 in the heat storage system is greater than the amount of heat removed from the heat storage unit 81 in the heat dissipation system, in order to maintain both functions.

Here, the heat stored in the heat storage material may be used by utilizing a heat storage system. Specifically, for example, a heat transfer medium at a lower temperature than the heat transfer medium 123 of the heat storage unit may be supplied to the heat storage unit 81 (heat exchange piping 124) via the heat transfer medium supply pipe 120 of the heat storage unit. In this case, the lower-temperature heat transfer medium supplied to the heat storage unit 81 absorbs heat from the heat storage material and is heated. This allows the heat transfer medium supplied from external equipment to be heated and returned to the external equipment, for example.

In this case, if the temperature detection unit 125 detects that the temperature of the heat transfer medium discharged from the heat storage unit 81 to the heat storage unit heat transfer medium discharge pipe 121 has fallen below a predetermined threshold, it means that the amount of heat stored in the heat storage unit 81 has fallen below the lower limit of heat storage. In this case, the supply of low-temperature heat transfer medium to the heat storage unit 81 is stopped.

Here, the predetermined threshold is set to the same threshold as the lower limit threshold mentioned above. That is, the predetermined threshold is set to 130°C, which is the lower limit of the reboiler's allowable temperature.

Furthermore, the low-temperature heat transfer medium may be supplied to the heat storage unit 81 from the heat storage unit heat transfer medium discharge pipe 121. In this case, the heat storage unit heat transfer medium supply pipe 120 is provided with a temperature detection unit that detects the temperature of the heat transfer medium discharged from the heat storage unit 81 (heat exchange piping 124).

According to the carbon dioxide recovery equipment 12 of the third embodiment described above, the heat storage function in the heat storage device 80 and the supply of the circulating heat medium 131 to the reboiler 40 can be performed independently. This allows for either performing only one of these functions, or performing both simultaneously.

Furthermore, in the reboiler heat transfer medium supply mechanism 50C of the carbon dioxide recovery equipment 12, the heat transfer medium 123 supplied from the external equipment can be returned to the external equipment without directly contacting the heat storage material of the heat storage device 80. Therefore, this is effective when purity is required for the heat transfer medium 123 returned to the external equipment.

In the reboiler heat transfer medium supply mechanism 50C, the circulating heat transfer medium 131 and the heat storage unit heat transfer medium 123 can be composed of different materials. In other words, the reboiler heat transfer medium supply mechanism 50C can accommodate cases where the materials of the circulating heat transfer medium 131 and the heat storage unit heat transfer medium 123 are different.

Furthermore, in the carbon dioxide recovery equipment 12, if excess high-temperature heat transfer fluid is generated in the plant or other source of the heat transfer fluid due to high-load operation, the heat storage device 80 can store the heat contained in the excess heat transfer fluid.

Thus, the carbon dioxide capture system 12 can effectively utilize the surplus heat generated by external facilities such as plants in the reboiler 40. Furthermore, even if load fluctuations occur in the plant or other heat transfer medium supply source, the reboiler 40 can properly heat the absorbent liquid.

(Fourth embodiment)
Figure 9 is a diagram of the reboiler heat transfer medium supply mechanism 50D in the carbon dioxide recovery equipment 13 of the fourth embodiment.

In the fourth embodiment of the carbon dioxide recovery system 13, the configuration is the same as that of the first embodiment of the carbon dioxide recovery system 10, except for the reboiler heat transfer medium supply mechanism 50D. Therefore, this section will mainly describe the configuration of the reboiler heat transfer medium supply mechanism 50D.

The reboiler heat transfer medium supply mechanism 50D is configured to supply a heat transfer medium to the reboiler 40. As shown in Figure 9, the reboiler heat transfer medium supply mechanism 50D includes a heat storage device 80 and a heating supply mechanism 70D.

Furthermore, the heat storage section 81 of the heat storage device 80 is composed of a latent heat storage material. The composition of the latent heat storage material is as described above.

The heating and supply mechanism 70D is configured to heat the heat storage section 81 of the heat storage device 80 and to supply the amount of heat stored in the heat storage section 81 to the reboiler 40. As shown in Figure 9, the heating and supply mechanism 70D includes a heat storage section heat transfer medium supply pipe 140, a heat storage section heat transfer medium discharge pipe 141, and a heat exchange piping 142.

The heat storage unit heat transfer medium supply pipe 140 supplies the heat storage unit heat transfer medium 143 to the heat exchange piping 142 installed in the reboiler 40. As the heat storage unit heat transfer medium 143, for example, steam (water vapor) generated in a thermal power plant, steel mill, or waste treatment plant equipped with a carbon dioxide recovery facility 10 is used. The heat storage unit heat transfer medium supply pipe 140 functions as a heat transfer medium supply pipe.

The heat storage unit heat transfer medium discharge pipe 141 discharges the heat storage unit heat transfer medium 143 supplied from the heat storage unit heat transfer medium supply pipe 140 through the heat exchange piping 142. For example, if the carbon dioxide recovery equipment 13 is installed in a thermal power plant equipped with a steam turbine, the heat storage unit heat transfer medium 143, which condenses into water in the heat exchange piping 142, is introduced into the feedwater pipe between the condenser and the boiler via the heat storage unit heat transfer medium discharge pipe 141. The heat storage unit heat transfer medium discharge pipe 141 functions as a heat transfer medium discharge pipe.

The heat storage unit's heat transfer medium discharge pipe 141 is equipped with a temperature detection unit 144 that detects the temperature of the heat storage unit's heat transfer medium 143 discharged from the heat storage unit 81 (heat exchange piping 142). The temperature detection unit 144 is located on the heat storage unit's heat transfer medium discharge pipe 141 on the reboiler 40 side.

Within the reboiler 40, for example, heat exchange piping 142 is arranged in a meandering pattern. One end of the heat exchange piping 142 is connected to the heat storage unit's heat transfer medium supply pipe 140. The other end of the heat exchange piping 142 is connected to the heat storage unit's heat transfer medium discharge pipe 141.

The heat storage device 80 is installed to surround the heat exchange piping 142. Specifically, the heat storage device 80 is constructed by filling a tubular container, provided along the heat exchange piping 142, with multiple latent heat storage materials. The latent heat storage materials are filled into the tubular container so as to be in contact with the heat exchange piping 142. The heat storage section 81 is then constructed within the tubular container.

Here, the circulation piping 41 that circulates lean liquid 32 (absorbent liquid) from the reboiler 40 to the regeneration tower 30 is equipped with a temperature detection unit 42 that detects the temperature of the lean liquid 32 discharged from the reboiler 40. The temperature detection unit 42 is provided in the circulation piping 41 on the reboiler 40 side.

Next, the operation of the reboiler heat transfer medium supply mechanism 50D will be explained.

Here, at the start of operation, it is preferable that the heat storage section 81 of the heat storage device 80 is in the initial state described above.

First, we will explain the process of heat storage in the heat storage device 80.

During heat storage, the heat storage unit's heat transfer medium 143 is supplied from the heat storage unit's heat transfer medium supply pipe 140 to the heat storage unit 81 (heat exchange piping 142). The temperature of the heat storage unit's heat transfer medium 143 supplied from the heat storage unit's heat transfer medium supply pipe 140 to the heat storage unit 81 is set, for example, to the reboiler's allowable temperature. The temperature of the heat storage unit's heat transfer medium 143 is set to correspond to the set heating temperature of the heat storage material in the heat storage unit 81.

The heat storage fluid 143 supplied to the heat storage unit 81 (heat exchange piping 142) via the heat storage unit heat fluid supply pipe 140 heats the heat storage material provided around the heat exchange piping 142. As a result, the heat storage material stores heat. The heat storage fluid 143, from which heat has been absorbed by the heat storage unit 81, is discharged from the heat exchange piping 142 to the heat storage unit heat fluid discharge pipe 141. In this case, the supply of heat storage fluid 143 to the heat exchange piping 142 is stopped.

Here, when the temperature detection unit 125 detects that the temperature of the heat storage fluid 143 discharged from the heat storage unit 81 is equal to the temperature of the heat storage fluid 143 supplied to the heat storage unit 81, it means that the amount of heat stored in the heat storage unit 81 has exceeded the upper limit of heat storage capacity.

Next, the process of heat dissipation in the heat storage device 80 will be explained.

The lean liquid 32 (absorbent liquid) introduced into the reboiler 40 from the circulation piping 41 flows around the heat storage device 80, absorbing heat from the heat storage material. This heats the lean liquid 32 to the reboiler's allowable temperature. The heated lean liquid 32 is discharged from the reboiler 40 and supplied to the regeneration tower 30 via the circulation piping 41.

Here, when the temperature of the lean liquid 32 discharged from the reboiler 40 falls below a predetermined threshold, it means that the amount of heat stored in the heat storage unit 81 has fallen below the lower limit of heat storage. In this case, the predetermined threshold is the set temperature (approximately 110-130°C) of the lean liquid 32 circulated from the reboiler 40 to the regeneration tower 30. In this case, the circulation of the lean liquid 32 from the reboiler 40 to the regeneration tower 30 is stopped.

Furthermore, the heat storage process described above may be performed during the heat dissipation process.

According to the carbon dioxide recovery equipment 13 of the fourth embodiment described above, by equipping the reboiler 40 with a heat storage device 80, the configuration of the reboiler heat transfer medium supply mechanism 50D can be made more compact.

In the reboiler heat transfer medium supply mechanism 50D shown in Figure 9, the heat transfer medium 143 supplied from the external equipment can be returned to the external equipment without directly contacting the heat storage material of the heat storage device 80. Therefore, this mechanism is effective when purity is required for the heat transfer medium 143 returned to the external equipment.

Furthermore, in the carbon dioxide capture equipment 13, if excess high-temperature heat transfer fluid is generated in the plant or other source of the heat transfer fluid due to high-load operation, the heat storage device 80 can store the heat contained in the excess heat transfer fluid.

Thus, the carbon dioxide capture system 13 can effectively utilize the surplus heat generated by external facilities such as plants in the reboiler 40. Furthermore, even if load fluctuations occur in the plant or other heat transfer medium supply source, the reboiler 40 can properly heat the absorbent liquid.

Here, the configuration of the reboiler heat transfer medium supply mechanism 50D is not limited to the configuration described above. Figure 10 is a system diagram of another configuration of the reboiler heat transfer medium supply mechanism 50D in the carbon dioxide recovery equipment 13 of the fourth embodiment.

As shown in Figure 10, a heat exchange piping 142 and a heat storage device 80 may be provided in the circulation system of the lean liquid 32 (absorbent liquid). Specifically, for example, the heat exchange piping 142 is arranged in a meandering manner within the reboiler 40. One end of the heat exchange piping 142 is connected to a circulation piping 41 that discharges the lean liquid 32 from the reboiler 40. The other end of the heat exchange piping 142 is connected to a circulation piping 41 that returns the lean liquid 32 to the reboiler 40.

The heat storage device 80 is installed to surround the heat exchange piping 142. The configuration of the heat storage device 80 is the same as that described with reference to Figure 9.

In the reboiler heat transfer medium supply mechanism 50D shown in Figure 10, when heat is stored, the heat transfer medium 143 is supplied from the heat transfer medium supply pipe 140 to the reboiler 40. The heat transfer medium 143 supplied to the reboiler 40 flows around the heat storage device 80, heating the heat storage material provided around the heat exchange piping 142. As a result, the heat storage material stores heat. The heat transfer medium 143, from which heat has been absorbed by the heat storage unit 81, is discharged from the reboiler 40 to the heat transfer medium discharge pipe 141.

Meanwhile, during heat dissipation, the lean liquid 32 (absorbent liquid) introduced into the reboiler 40 from the circulation piping 41 flows through the heat exchange piping 142, absorbing heat from the heat storage material. This heats the lean liquid 32 to the aforementioned set temperature. The heated lean liquid 32 generates steam (water vapor). The lean liquid 32 containing the steam is then introduced from the heat exchange piping 142 into the circulation piping 41 and supplied to the regeneration tower 30.

In the other configuration of the reboiler heat transfer medium supply mechanism 50D shown in Figure 10, the configuration of the reboiler heat transfer medium supply mechanism 50D can be made more compact by incorporating a heat storage device 80 within the reboiler 40.

Furthermore, in other configurations of the reboiler heat transfer medium supply mechanism 50D, if excess high-temperature heat transfer medium is generated in the plant or other source of the heat transfer medium due to high-load operation, the heat storage device 80 can store the heat contained in the excess heat transfer medium.

Thus, in the reboiler heat transfer medium supply mechanism 50D with other configurations, surplus heat generated by external facilities such as plants can be effectively utilized in the reboiler 40. Furthermore, even when load fluctuations occur in the plant or other source of the heat transfer medium, the absorbent liquid can be properly heated in the reboiler 40.

In the embodiments described above, the heat storage unit may be equipped with an electric heater along with a heat transfer medium as a heating means.

According to the embodiments described above, the heat supplied from external equipment such as a plant can be effectively utilized in the reboiler, and the absorbent liquid can be properly heated in the reboiler.

While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications are possible without departing from the spirit of the invention. These embodiments and their variations are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as described in the claims.

10, 11, 12, 13... Carbon dioxide recovery equipment, 20... Absorption tower, 21... Absorption section, 22... Discharge port, 23... Rich liquid, 24... Exhaust gas inlet pipe, 24a... Exhaust gas blower, 25... Rich liquid inlet pipe, 26... Heat exchanger, 27... Pump for rich liquid, 30... Regeneration tower, 31... Regeneration section, 32... Lean liquid, 33... Carbon dioxide discharge port, 34... Carbon dioxide discharge pipe, 35... Gas-liquid separation device, 35 a...Recovery port, 35b...Drain pipe, 36, 39...Cooler, 37...Lean liquid inlet pipe, 38...Lean liquid pump, 40...Reboiler, 41, 130...Circulation piping, 42, 63, 75, 76, 94, 95, 125, 133, 144...Temperature sensing unit, 50A, 50B, 50C, 50D...Reboiler heat transfer medium supply mechanism, 60, 93...Reboiler heat transfer medium supply pipe, 61...Reboiler heat transfer medium discharge pipe , 62... Reboiler heat medium, 70A, 70B, 70C, 70D... Heating supply mechanism, 71... Communication piping, 72... Heat medium discharge pipe, 72a, 73a, 85a, 91a, 92a, 100a... Flow rate Regulating valve, 73, 92, 120, 140... Heat storage unit heat medium supply pipe, 74, 123, 143... Heat storage unit heat medium, 80... Heat storage device, 81, 81A, 81B, 81C, 81D... Heat storage unit, 82... Supply Water pipe, 83... Drain pipe, 84, 124, 142... Heat exchange piping, 85, 100... Bypass pipe, 86... Device container, 87... Chemical heat storage material, 88... Container, 90... High-temperature heat transfer medium introduction pipe, 91... Low-temperature heat transfer medium introduction pipe, 110, 111... Connecting pipes, 121, 141... Heat storage section heat transfer medium discharge pipe, 130A... Supply circulation piping, 130B... Return circulation piping, 131... Circulating heat transfer medium, 132... Circulation pump.

Claims (4)

The exhaust gas to be treated, which contains carbon dioxide, is introduced into an absorption tower that absorbs carbon dioxide into an absorbent liquid containing water,
A regeneration tower that releases carbon dioxide from the absorbent liquid supplied from the absorption tower,
A reboiler that heats the absorbent liquid in the regeneration tower to generate steam,
A heat storage unit that generates steam from the absorbent liquid in the reboiler and stores the amount of heat required to supply the reboiler heat transfer medium at an allowable reboiler temperature to the reboiler,
The system includes a heating and supply mechanism that heats the heat storage section and supplies the amount of heat stored in the heat storage section to the reboiler,
The aforementioned heating supply mechanism
A heat storage unit heat medium supply pipe supplies a first heat medium, which is excess heat medium generated in the external equipment that satisfies the allowable temperature of the reboiler, to the heat storage unit.
A heat storage unit heat medium discharge pipe for discharging the first heat medium from the heat storage unit,
The heat storage unit and the reboiler are provided with circulation piping for circulating a circulating heat medium that functions as the heat medium for the reboiler,
When heat is stored in the heat storage section,
The first heat transfer medium introduced into the heat storage unit via the heat transfer medium supply pipe provides the heat to the heat storage unit and is discharged from the heat storage unit via the heat transfer medium discharge pipe.
When heat is released from the heat storage unit,
A carbon dioxide recovery system characterized in that the circulating heat medium introduced into the heat storage unit via the circulation piping absorbs the heat from the heat storage unit to satisfy the allowable temperature of the reboiler and is supplied to the reboiler via the circulation piping. The carbon dioxide recovery apparatus according to claim 1, characterized in that the heat storage section comprises a latent heat storage material. The carbon dioxide recovery apparatus according to claim 1, characterized in that the heat storage section comprises a sensible heat storage material. The heat storage unit is
A first heat storage unit equipped with a sensible heat storage material,
A second heat storage unit equipped with a latent heat storage material,
The carbon dioxide recovery equipment according to claim 1, further comprising a connecting pipe that connects the first heat storage unit and the second heat storage unit.