JP2023068025A - Carbon dioxide recovery system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a carbon dioxide recovery system which can efficiently recover carbon dioxide contained in exhaust gas of an engine without affecting operation of the engine.

SOLUTION: A carbon dioxide recovery system 100 includes: an absorption part 1; an exhaust gas supply path 30; and a booster machine 33 and separates CO₂ from exhaust gas of an engine 10 to recover the CO₂. The absorption part 1 causes an absorbent to absorb CO₂ contained in the exhaust gas. The exhaust gas supply path 30 supplies the exhaust gas to the absorption part 1. The booster machine 33 increases a pressure of the exhaust gas.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2023,JPO&INPIT

Description

The present invention relates to a carbon dioxide recovery system for separating and recovering carbon dioxide contained in engine exhaust gas.

BACKGROUND ART Conventionally, a carbon dioxide recovery system using an absorbent is known as a technique for reducing carbon dioxide emissions into the atmosphere in order to prevent global warming. Patent Literature 1 discloses this type of carbon dioxide capture device.

Although the carbon dioxide capture device of Patent Document 1 is not intended for engine exhaust gas, it is used for combustion exhaust gas emitted from boilers and gas turbines such as thermal power plants, and process exhaust gas generated at ironworks. It recovers carbon dioxide contained in, etc. The carbon dioxide recovery apparatus of Patent Document 1 includes an absorption tower that absorbs exhaust gas into an absorbent, and a regeneration tower that separates carbon dioxide and regenerates the absorbent. After the exhaust gas is cooled in the cooling tower, , is supplied to the absorber via a flue.

JP 2015-163381 A

In the configuration of Patent Document 1, exhaust gas pressurized by an exhaust gas blower or the like is cooled in a cooling tower and then supplied to an absorption tower. Therefore, the pressure of the exhaust gas tends to be insufficient at the exhaust gas inlet of the absorption tower. In particular, when the configuration of Patent Document 1 is used to recover carbon dioxide from the exhaust gas of an engine, the pressure of the exhaust gas at the exhaust gas inlet of the absorber tower decreases because the exhaust gas of the engine is relatively low temperature and low pressure. It is considered that it becomes remarkable and the recovery rate of carbon dioxide decreases. Furthermore, the pressure loss generated in the absorption tower makes it difficult to exhaust the engine, which may affect the combustion of the engine.

The present invention has been made in view of the above circumstances, and its object is to provide a carbon dioxide recovery system capable of efficiently recovering carbon dioxide contained in engine exhaust gas without affecting engine operation. be.

A carbon dioxide recovery system according to one aspect of the present invention separates and recovers carbon dioxide from an engine exhaust gas. The carbon dioxide recovery system includes an absorber, an exhaust gas supply route, and a booster. The absorption part causes an absorption liquid to absorb carbon dioxide contained in the exhaust gas. The exhaust gas supply path supplies the exhaust gas to the absorber. The booster boosts the exhaust gas.

According to the present invention, it is possible to provide a carbon dioxide recovery system capable of efficiently recovering carbon dioxide contained in engine exhaust gas without affecting engine operation.

1 is a schematic diagram showing the configuration of a carbon dioxide recovery system according to a first embodiment of the present invention; FIG. The schematic diagram which shows the structure of the carbon-dioxide recovery system of 2nd Embodiment. The schematic diagram which shows the structure of the carbon-dioxide recovery system of 3rd Embodiment. The schematic diagram which shows the structure of the carbon-dioxide recovery system of 4th Embodiment. The schematic diagram which shows the structure of the carbon-dioxide recovery system of 5th Embodiment. The schematic diagram which shows the structure of the carbon-dioxide recovery system of 6th Embodiment. The schematic diagram which shows the structure of the carbon-dioxide recovery system of 7th Embodiment. The schematic diagram which shows the structure of the carbon-dioxide collection|recovery system of a 1st modification. The schematic diagram which shows the structure of the carbon-dioxide collection|recovery system of a 2nd modification.

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing the overall configuration of a carbon dioxide recovery system 100 according to the first embodiment of the present invention. In the following description, "upstream" and "downstream" mean upstream and downstream in the flow direction of exhaust gas, decarbonated gas, absorbent, and _CO2 .

A carbon dioxide recovery system 100 shown in FIG. 1 is configured as a system that separates and recovers carbon dioxide (CO ₂ ) contained in the exhaust gas of an engine 10 using an absorbent.

Examples of this absorption liquid include a chemical absorption liquid (amine solution, ammonia water, etc.) that absorbs _CO2 using a chemical reaction with _CO2 , or a liquid that uses physical dissolution of _CO2 under high pressure. A physical absorption liquid (such as an ionic liquid) that absorbs CO ₂ can be used. In the following description, an absorbent containing a high concentration of CO ₂ is sometimes referred to as a rich absorbent, and an absorbent containing a low concentration of CO ₂ is sometimes referred to as a lean absorbent. .

The configuration of the engine 10 is not particularly limited as long as the exhaust gas contains CO ₂ . The engine 10 can be configured as, for example, a gas engine using gaseous fuel, a gasoline engine or a diesel engine using liquid fuel, or the like.

The carbon dioxide recovery system 100, as shown in FIG. , and a control device 5 .

The carbon dioxide absorption part 1 is configured as an absorption chamber for absorbing CO ₂ and brings the exhaust gas into contact with the lean absorption liquid. As a result, the CO ₂ contained in the exhaust gas is absorbed by the lean absorbent to produce a rich absorbent.

The carbon dioxide absorber 1 is formed with an exhaust gas inlet (exhaust gas inlet) 11 , a lean absorbent inlet 12 , a rich absorbent outlet 13 , and a decarbonated gas outlet 14 . A predetermined amount of absorbing liquid is stored in the lower portion of the carbon dioxide absorbing portion 1 .

The exhaust gas inlet 11 is formed below the carbon dioxide absorption part 1 . The exhaust gas inlet 11 is connected to the exhaust gas supply section 3 and introduces exhaust gas from the engine 10 . By providing the exhaust gas introduction port 11 in the lower part of the carbon dioxide absorption part 1, CO ₂ can be introduced into the absorbent stored in the carbon dioxide absorption part 1. FIG.

A lean absorbent inlet 12 is formed at the top of the carbon dioxide absorption section 1 . The lean absorbent inlet 12 is connected to the absorbent circulation section 4 and introduces the absorbent (lean absorbent) regenerated by the absorbent regeneration section 2 .

A rich absorbent outlet 13 is formed in the lower portion of the carbon dioxide absorber 1 . The rich absorbent discharge port 13 is connected to the absorbent circulation section 4 and discharges the rich absorbent produced in the carbon dioxide absorption section 1 so as to supply it to the absorbent regeneration section 2 .

A decarbonation gas outlet 14 is formed at the top of the carbon dioxide absorption part 1 . The decarbonated gas outlet 14 discharges decarbonated gas (second exhaust gas), which is exhaust gas from which CO ₂ has been separated.

In the carbon dioxide absorption unit 1 configured as described above, the exhaust gas is introduced into the stored absorbent, and the exhaust gas and the absorbent are mixed to absorb the CO ₂ contained in the exhaust gas. Absorbed in liquid.

Then, while the exhaust gas (including decarbonated gas) floating from the stored absorbent is flowing toward the upper part of the carbon dioxide absorbing part 1, it is introduced from the lean absorbent inlet 12 provided at the top. Any CO ₂ that comes into contact with the lean absorbent and remains in the exhaust gas is absorbed by the lean absorbent. The lean absorbent absorbs CO ₂ to become a rich absorbent, drops to the lower part of the carbon dioxide absorption section 1 , is discharged through the rich absorbent discharge port 13 , and is supplied to the absorbent regeneration section 2 .

The absorbent regeneration unit 2 is configured as a separation chamber for separating CO ₂ from the rich absorbent. The absorbent regeneration unit 2 recovers CO ₂ by separating CO ₂ from the heated rich absorbent and also regenerates the rich absorbent to generate lean absorbent.

As the absorbent regenerator 2, for example, a gas-liquid separator using centrifugal force, gravity, or the like can be used. In the absorbent regeneration unit 2, the rich absorbent heating unit 44, which will be described later, heats the rich absorbent, thereby separating _CO2 from the rich absorbent and producing lean absorbent.

The absorbent regeneration unit 2 is formed with a rich absorbent inlet 21 , a lean absorbent outlet 22 and a carbon dioxide outlet 23 .

The rich absorbent inlet 21 is formed in the middle or upper portion of the absorbent regeneration unit 2 in the height direction. The rich absorbent introduction port 21 is connected to the absorbent circulation section 4 and introduces the rich absorbent supplied from the carbon dioxide absorption section 1 into its interior.

The lean absorbent discharge port 22 is formed at the bottom of the absorbent regeneration unit 2 . The lean absorbent discharge port 22 is connected to the absorbent circulation section 4 and discharges the produced lean absorbent so as to supply it to the carbon dioxide absorbent section 1 .

A carbon dioxide outlet 23 is formed at the top of the absorbent regeneration unit 2 . A carbon dioxide outlet 23 discharges the CO ₂ separated from the rich absorbent. A carbon dioxide discharge path 24 is connected to the carbon dioxide discharge port 23 .

The carbon dioxide discharge path 24 is formed from piping through which CO ₂ flows. The carbon dioxide discharge path 24 guides the CO ₂ separated in the absorbent regeneration unit 2 to the outside.

The exhaust gas supply unit 3 is provided between the engine 10 that is a source of exhaust gas and the carbon dioxide absorption unit 1 . The exhaust gas supply unit 3 supplies exhaust gas from the engine 10 to the carbon dioxide absorption unit 1 . The exhaust gas supply unit 3 includes an exhaust gas supply path 30 , an exhaust gas condenser 31 , a first gas-liquid separator 32 , and an exhaust gas booster (booster) 33 .

The exhaust gas supply path 30 is formed of a pipe through which the exhaust gas flows. The exhaust gas supply path 30 connects an exhaust pipe (not shown) of the engine 10 and the exhaust gas inlet 11 of the carbon dioxide absorber 1 . The exhaust gas supply path 30 supplies the exhaust gas from the engine 10 into the carbon dioxide absorber 1 through the exhaust gas introduction port 11 .

The exhaust gas condenser 31 is provided in the exhaust gas supply path 30 on the downstream side of the engine 10 . The exhaust gas condenser 31 cools the high-temperature exhaust gas discharged from the engine 10 by exchanging heat with a coolant such as cooling water to condense water vapor contained in the exhaust gas.

In the exhaust gas condenser 31, the water vapor contained in the exhaust gas is condensed into a liquid state. The gas-liquid mixed exhaust gas discharged from the exhaust gas condenser 31 is supplied to the first gas-liquid separator 32 .

The first gas-liquid separator 32 is provided in the exhaust gas supply path 30 on the downstream side of the exhaust gas condenser 31 . The first gas-liquid separator 32 separates the moisture contained in the supplied exhaust gas using, for example, centrifugal force or surface tension. The first gas-liquid separator 32 discharges the water separated from the exhaust gas, and supplies the exhaust gas (dry exhaust gas) from which moisture has been separated to the exhaust gas booster 33 .

By providing the exhaust gas condenser 31 and the first gas-liquid separator 32, moisture contained in the exhaust gas can be preferably removed, and dilution of the absorbing liquid by the moisture can be avoided.

The exhaust gas pressure increasing device 33 is provided in the exhaust gas supply path 30 on the downstream side of the first gas-liquid separator 32 and closer to the carbon dioxide absorber 1 . The exhaust gas booster 33 is composed of, for example, a blower. The target pressure increase amount of the exhaust gas pressure increasing device 33 is controlled based on the rotational speed of the engine 10 and the like (details will be described later).

By providing the exhaust gas pressurization device 33 on the downstream side of the first gas-liquid separator 32, it is possible to avoid supplying the exhaust gas containing moisture to the exhaust gas pressurization device 33. Deterioration (for example, generation of rust) can be avoided.

The exhaust gas pressurizing device 33 is provided at a position higher than the bottom of the carbon dioxide absorber 1 . Specifically, the height of the exhaust gas pressurizing device 33 is higher than the height of the bottom portion of the carbon dioxide absorber 1 by a predetermined distance.

The predetermined distance is preferably set higher than the stop liquid level, which is the liquid level of the absorbing liquid stored inside the carbon dioxide absorption unit 1 after the carbon dioxide recovery system 100 stops. As a result, when the carbon dioxide recovery system 100 is stopped, even if the absorbent in the carbon dioxide absorption unit 1 flows back into the exhaust gas supply path 30 due to the difference in water head, the absorbent reaches the exhaust gas pressurization device 33. can be avoided.

Regarding the start-up of the carbon dioxide recovery system 100, in order to avoid the influence on the operation of the engine 10 due to the unstable air pressure in the exhaust gas supply path 30, in this embodiment, the exhaust gas pressurization device 33 starts the operation of the engine 10. is activated a predetermined time (for example, 10 minutes before). As a result, the exhaust gas generated by the operation of the engine 10 can be smoothly discharged from the engine 10 and supplied to the carbon dioxide absorber 1, and the load on the engine 10 can be reduced. In addition, abnormal combustion of the engine 10 due to poor discharge of exhaust gas can be prevented.

Regarding stopping the carbon dioxide recovery system 100, in the present embodiment, the exhaust gas booster 33 is stopped after a predetermined time (for example, 10 minutes) after the engine 10 stops. As a result, the exhaust gas can be prevented from remaining in the exhaust gas supply path 30 .

The absorbent circulating section 4 is provided between the carbon dioxide absorbing section 1 and the absorbent regenerating section 2 and circulates the absorbent between the carbon dioxide absorbing section 1 and the absorbent regenerating section 2 . The absorbent circulation section 4 includes a rich absorbent circulation path (absorbent discharge path) 41 , a lean absorbent circulation path (absorbent reflux path) 42 , an absorbent heat exchange section 43 , and a rich absorbent heating section 44 . , provided.

The rich absorbent circulation path 41 is formed of a pipe through which the rich absorbent flows. The rich absorbent circulation path 41 connects the rich absorbent outlet 13 of the carbon dioxide absorber 1 and the rich absorbent inlet 21 of the absorbent regeneration section 2 . The rich absorbent circulation path 41 supplies the rich absorbent discharged from the carbon dioxide absorption section 1 to the absorbent regeneration section 2 .

A rich absorbent pump 45 is provided upstream of the absorbent heat exchange section 43 in the rich absorbent circulation path 41 . The rich absorbent pump 45 pumps the rich absorbent discharged from the carbon dioxide absorption section 1 to the absorbent heat exchange section 43 so as to supply the rich absorbent to the absorbent regeneration section 2 .

The lean absorbent circulation path 42 is formed of a pipe through which the lean absorbent flows. The lean absorbent circulation path 42 connects the lean absorbent discharge port 22 of the absorbent regeneration unit 2 and the lean absorbent inlet 12 of the carbon dioxide absorption unit 1 . The lean absorbent circulation path 42 supplies the lean absorbent discharged from the absorbent regeneration unit 2 to the carbon dioxide absorption unit 1 .

A lean absorbent pump 46 is provided on the downstream side of the absorbent heat exchange section 43 in the lean absorbent circulation path 42 . The lean absorbent pump 46 forcibly pumps the lean absorbent cooled by the absorbent heat exchange section 43 so as to introduce it into the carbon dioxide absorbing section 1 through the lean absorbent inlet 12 .

The absorbent heat exchange section 43 is provided in the middle of the rich absorbent circulation path 41 and the lean absorbent circulation path 42 . The absorbent heat exchange section 43 is configured as part of each of the rich absorbent circulation path 41 and the lean absorbent circulation path 42 .

That is, in the absorbent heat exchange section 43, there are the relatively low-temperature rich absorbent discharged from the carbon dioxide absorbing section 1 and the relatively high-temperature lean absorbent discharged from the absorbent regeneration section 2. and have been introduced.

In the absorbent heat exchange section 43, heat is exchanged between the lean absorbent having a high temperature and the rich absorbent having a low temperature. As a result, the lean absorbent supplied to the carbon dioxide absorption unit 1 is cooled, and the rich absorbent supplied to the absorbent regeneration unit 2 is heated. That is, the heat contained in the lean absorbent regenerated by the absorbent regenerating unit 2 can be utilized, and energy saving can be achieved.

The rich absorbent heating section 44 is provided in the rich absorbent circulation path 41 on the downstream side of the absorbent heat exchange section 43 and heats the rich absorbent supplied to the absorbent regeneration section 2 . The rich absorbent heating unit 44 is composed of, for example, a heat exchanger. The rich absorbent heating unit 44 of the present embodiment heats the rich absorbent flowing therein by using cooling water whose temperature has been increased by cooling the engine 10 .

Heating the rich absorbent enhances the separation of _CO2 from the rich absorbent. Any type of heat exchanger can be used as the heat exchanger that constitutes the rich absorbent heating unit 44, but a plate type is preferable in consideration of simplification of the device and ease of disassembly for cleaning.

With this configuration, the exhaust heat (usually 100° C. or less) generated by the engine 10 can be used to separate CO ₂ from the rich absorbent.

The control device 5 includes a CPU, a ROM, a RAM, etc., and controls each part of the carbon dioxide recovery system 100 based on control data such as a prescribed boost amount (boost amount) stored in the ROM. The control device 5 controls the operation of the exhaust gas pressure increasing device 33, for example, based on the stored specified pressure increasing amount. As the control device 5, for example, an ECU (Engine Control Unit) provided in the engine 10 and controlling the operation of the engine 10 can be used.

This prescribed boost amount is determined by the number of revolutions of the engine 10 or a parameter that changes with changes in the number of revolutions (for example, the flow rate of the exhaust gas discharged by the engine 10, that is, the flow rate of the exhaust gas in the exhaust gas supply path 30). It is determined based on

The prescribed boost amount is determined to compensate for changes in the exhaust gas pressure (exhaust gas pressure at the exhaust gas inlet 11 of the carbon dioxide absorber 1) accompanying changes in the engine 10 speed or exhaust gas flow rate. It is As a result, the pressure of the exhaust gas (the pressure at the exhaust gas introduction port 11) can always be maintained at a predetermined value. Therefore, it is possible to avoid a change in the absorption rate of CO ₂ in the carbon dioxide absorption part 1 due to the pressure of the exhaust gas.

During the operation of the carbon dioxide recovery system 100, the control device 5 instructs the exhaust gas pressurization device 33 to set a prescribed pressurization amount based on the number of rotations of the engine 10 or the flow rate of the exhaust gas as the target pressurization amount of the exhaust gas pressurization device 33. The exhaust gas pressurization device 33 operates to achieve the instructed target pressurization amount.

Note that the rotation speed of the engine 10 can be detected by a rotation speed sensor (not shown) provided in the engine 10 . Further, the flow rate of the exhaust gas may be detected by an unillustrated exhaust gas flow rate sensor provided in the engine 10 or may be detected by providing an exhaust gas flow rate sensor in the exhaust gas supply path 30 .

With the above configuration, the carbon dioxide recovery system 100 of the present embodiment can stably supply exhaust gas having a predetermined pressure to the carbon dioxide absorber 1 . In the carbon dioxide absorption section 1, the lean absorbent supplied from the absorbent regeneration section 2 is used to absorb CO ₂ contained in the exhaust gas to produce a rich absorbent. The rich absorbent produced in the carbon dioxide absorption section 1 is supplied to the absorbent regeneration section 2 . In the absorbent regeneration unit 2 , CO ₂ is recovered by separating it from the heated rich absorbent, and the produced lean absorbent is supplied to the carbon dioxide absorption unit 1 . By separating the CO ₂ contained in the exhaust gas and discharging it through the carbon dioxide discharge path 24 in this manner, the CO ₂ can be recovered.

In addition, the carbon dioxide recovery system 100 of the present embodiment can obtain high-concentration CO 2 by a separation method using a conventional carbon dioxide separation membrane, etc., and can produce high-concentration CO ₂ at a lower cost than the production of carbon dioxide gas. ₂ can be obtained, it is suitable for providing CO ₂ to greenhouse horticulture, etc., which will be described later.

In the carbon dioxide recovery system 100 of the present embodiment, when an abnormal state is detected, the control device 5 operates the carbon dioxide recovery system 100 (specifically, for separating and regenerating CO ₂ from the exhaust gas). Related actions) are controlled to stop. Examples of the abnormal state include a state in which liquid leakage occurs, a state in which the flow rate of the rich absorbent supplied to the absorbent regenerating unit 2 is exceeded, and the like.

Specifically, in the carbon dioxide recovery system 100 of the present embodiment, in the paths such as the rich absorbent circulation path 41 and the lean absorbent circulation path 42 where the absorbent flows, locations where liquid leakage is likely to occur (for example, connection (parts, etc.) is provided with a liquid leakage sensor (not shown). The liquid leakage sensor is provided so as to be able to communicate with the control device 5 by wire or wirelessly, and transmits a liquid leakage signal or the like to the control device 5 when liquid leakage is detected.

In this manner, the control device 5 stops the operation of the carbon dioxide recovery system 100 when the liquid leakage sensor detects that liquid leakage has occurred in the path through which the absorbent flows.

Further, the controller 5 determines that the flow rate of the absorbent supplied to the absorbent regeneration unit 2 exceeds the flow rate of the absorbent discharged from the absorbent regeneration unit 2 by a predetermined threshold value (for example, 0.5 L/min) or more. When it is detected that the state has continued for a predetermined time (for example, 5 minutes), the operation of the carbon dioxide recovery system 100 is stopped. The flow rate of the absorbent supplied to the absorbent regeneration unit 2 is adjusted by the rich absorbent pump 45 . The flow rate of the absorbent discharged from the absorbent regeneration unit 2 is adjusted by the lean absorbent pump 46 . Each flow rate can be obtained using a flow meter or the like (not shown). As a result, it is possible to prevent the excess amount of the absorbent in the absorbent regenerating section 2 and the overflow of the absorbent from the top.

As described above, the carbon dioxide recovery system 100 of this embodiment separates and recovers CO ₂ from the exhaust gas of the engine 10 . The carbon dioxide recovery system 100 includes a carbon dioxide absorber 1 , an exhaust gas supply path 30 , an exhaust gas pressure increasing device 33 and a control device 5 . The carbon dioxide absorption part 1 brings the exhaust gas into contact with the lean absorbent, and causes the lean absorbent to absorb CO ₂ contained in the exhaust gas. The exhaust gas supply path 30 supplies exhaust gas from the engine 10 to the carbon dioxide absorber 1 . The exhaust gas pressurization device 33 is provided in the exhaust gas supply path 30 on the upstream side of the carbon dioxide absorber 1 in the direction in which the exhaust gas flows, and pressurizes the exhaust gas. The control device 5 controls the target amount of pressurization of the exhaust gas by the exhaust gas pressurization device 33 according to the rotation speed of the engine 10 or a parameter that changes with changes in the rotation speed.

As a result, the pressure of the exhaust gas supplied to the carbon dioxide absorption part 1 can be increased, and a decrease in the absorption rate of CO ₂ due to a decrease in pressure can be avoided. Further, by increasing the pressure of the exhaust gas supplied to the carbon dioxide absorption section 1 according to the rotational speed of the engine 10, etc., the pressure loss generated in the carbon dioxide absorption section 1 can be compensated. Therefore, since there is no resistance to the flow of exhaust gas from the engine 10, it is possible to prevent the combustion of the engine 10 from being affected.

Further, in the carbon dioxide recovery system 100 of this embodiment, the parameters include the flow rate of the exhaust gas in the exhaust gas supply path 30 . The specified pressure increase amount used by the control device 5 is such that the pressure of the exhaust gas at the exhaust gas inlet 11 of the carbon dioxide absorption unit 1 is maintained at a predetermined value even if the rotation speed or the flow rate of the exhaust gas changes. Alternatively, it is determined corresponding to the flow rate of the exhaust gas. The control device 5 controls the exhaust gas pressurization device 33 by setting the specified pressurization amount corresponding to the rotation speed or the flow rate of the exhaust gas as the target pressurization amount of the exhaust gas pressurization device 33. do.

As a result, the pressure of the exhaust gas supplied to the carbon dioxide absorption part 1 can be kept constant, and the absorption rate of CO ₂ can be suitably maintained.

Next, second to seventh embodiments will be described. In the following description of the embodiments, the same or similar members as those of the above-described embodiments are denoted by the same reference numerals in the drawings, and descriptions thereof may be omitted.

The carbon dioxide recovery system 100a of the second embodiment includes a lean absorbent cooling section (second cooling section) 47, as shown in FIG. The lean absorbent cooling unit 47 is composed of, for example, a water-cooled cooler, and cools the lean absorbent flowing therein by heat exchange with cooling water.

The lean absorbent cooling unit 47 is provided in the lean absorbent circulation path 42 on the downstream side of the lean absorbent pump 46, and cools the lean absorbent supplied to the carbon dioxide absorbing unit 1 before the carbon dioxide absorbing unit 1. Cooling. In this way, by supplying the cooled lean absorbent to the carbon dioxide absorbing section 1, it is possible to avoid the temperature rise in the carbon dioxide absorbing section 1 due to the hot lean absorbent discharged from the absorbent regeneration section 2, The environmental temperature suitable for the CO ₂ absorption reaction in the carbon dioxide absorption part 1 can be preferably maintained.

Further, the carbon dioxide recovery system 100a of the present embodiment may be provided with an exhaust gas cooling section (first cooling section) 34 in the exhaust gas supply path 30, as shown in FIG. This exhaust gas cooling unit 34 is preferably provided in the exhaust gas supply path 30 on the downstream side of the exhaust gas pressure increasing device 33 . As a result, the exhaust gas supplied to the carbon dioxide absorption section 1 can be cooled before the carbon dioxide absorption section 1 .

The exhaust gas cooling unit 34 is composed of, for example, a water-cooled cooler, and cools the exhaust gas flowing therein by heat exchange with cooling water. By using this configuration, it is possible to prevent the temperature of the lean absorbent in the carbon dioxide absorbing section 1 from rising due to the introduction of the exhaust gas, and to improve the CO ₂ absorption rate.

As described above, the carbon dioxide recovery system 100 a of the present embodiment includes the exhaust gas cooling section 34 provided in the exhaust gas supply path 30 and cooling the exhaust gas supplied to the carbon dioxide absorbing section 1 .

Thus, by cooling the exhaust gas supplied to the carbon dioxide absorption unit 1, the absorption rate of CO ₂ in the carbon dioxide absorption unit 1 can be improved.

Further, the carbon dioxide recovery system 100 a of this embodiment includes a lean absorbent cooling unit 47 . The lean absorbent cooling unit 47 is provided in the lean absorbent circulation path 42 and cools the lean absorbent flowing back to the carbon dioxide absorbing unit 1 .

As a result, by cooling the lean absorbent returned to the carbon dioxide absorption section 1, the absorption rate of CO ₂ in the absorption section can be improved.

The carbon dioxide recovery system 100b of the third embodiment includes a carbon dioxide post-treatment section 6 connected to the carbon dioxide discharge port 23 of the absorbent regeneration section 2, as shown in FIG.

The carbon dioxide post-treatment section 6 is provided in the carbon dioxide discharge path 24 on the downstream side of the absorbent regeneration section 2 . The carbon dioxide post-treatment section 6 removes the absorbent components contained therein from the CO ₂ discharged from the absorbent regeneration section 2 and then discharges the CO ₂ . The carbon dioxide post-treatment section 6 includes a carbon dioxide cooling section (fourth cooling section) 61 and a second gas-liquid separator (second absorbent separation section) 62 in this order from the upstream side in the direction in which CO ₂ flows. Prepare.

The carbon dioxide cooling section 61 uses a refrigerant such as cooling water to cool the CO ₂ discharged from the absorbent regeneration section 2, thereby condensing the absorbent components contained therein. The gas-liquid mixed CO ₂ discharged from the carbon dioxide cooling unit 61 is supplied to the second gas-liquid separator 62 .

The second gas-liquid separator 62 separates the absorption liquid contained in the supplied CO ₂ using, for example, centrifugal force or surface tension. A device having the same structure as the first gas-liquid separator 32 may be used as the second gas-liquid separator 62 . In this case, it is possible to simplify the configuration of the carbon dioxide recovery system 100b.

A first absorbent return path 63 is provided to connect the second gas-liquid separator 62 and the carbon dioxide absorber 1 . The first absorbent return path 63 is provided with a pump 64 for pressure-feeding the absorbent to the carbon dioxide absorption part 1 . The absorbent separated from CO ₂ by the second gas-liquid separator 62 is returned to the carbon dioxide absorption section 1 via the first absorbent return path 63 .

With this configuration, it is possible to prevent wasteful consumption of the absorbent due to being discharged together with CO ₂ , and to avoid discharge of the absorbent which is harmful to the environment.

As described above, the carbon dioxide recovery system 100b of this embodiment includes the carbon dioxide discharge path 24, the carbon dioxide cooler 61, and the second gas-liquid separator 62. A carbon dioxide discharge path 24 discharges the separated CO ₂ from the absorbent regeneration unit 2 . The second gas-liquid separator 62 is provided in the carbon dioxide discharge path 24 and cools the discharged CO ₂ . The second gas-liquid separator 62 is provided in the carbon dioxide discharge path 24 on the downstream side of the carbon dioxide cooling section 61 in the direction of CO ₂ flow, and separates the absorbent contained in the discharged CO ₂ .

As a result, it is possible to avoid the discharge of the absorbing liquid accompanying the discharge of CO ₂ and to suppress the consumption of the absorbing liquid.

The carbon dioxide recovery system 100c of the fourth embodiment includes a decarbonated gas processing unit 7 that processes the decarbonated gas discharged from the carbon dioxide absorption unit 1, as shown in FIG.

The decarbonation gas processing unit 7 removes the absorbent components contained therein from the decarbonation gas discharged from the carbon dioxide absorption unit 1, and then discharges the decarbonation gas. The decarbonation gas processing unit 7 includes a decarbonation gas discharge route (exhaust gas discharge route) 70, a decarbonation gas cooling unit 71 (third cooling unit), and a third gas-liquid separator 72 (first absorbent separation unit ) and

The decarbonated gas discharge path 70 is formed from a pipe through which the decarbonated gas flows. The decarbonated gas discharge path 70 is connected to the decarbonated gas discharge port 14 of the carbon dioxide absorber 1, and guides the decarbonated gas discharged from the carbon dioxide absorber 1 to the outside.

The decarbonated gas cooling unit 71 is provided in the decarbonated gas discharge path 70 on the downstream side of the carbon dioxide absorption unit 1 . The decarbonation gas cooling unit 71 uses a refrigerant such as cooling water to cool the decarbonation gas discharged from the carbon dioxide absorption unit 1, thereby condensing the absorption liquid component contained therein. The gas-liquid mixed decarbonated gas discharged from the decarbonated gas cooling unit 71 is supplied to the third gas-liquid separator 72 .

The third gas-liquid separator 72 is provided in the decarbonated gas discharge path 70 on the downstream side of the decarbonated gas cooling section 71 . The third gas-liquid separator 72 has substantially the same configuration as the first gas-liquid separator 32 and the second gas-liquid separator 62 . A second absorbent return path 73 is provided to connect the third gas-liquid separator 72 and the carbon dioxide absorber 1 . The second absorbent return path 73 is provided with a pump 74 for pressure-feeding the absorbent to the carbon dioxide absorption part 1 . The absorbent separated from the decarbonated gas by the third gas-liquid separator 72 is returned to the carbon dioxide absorber 1 via the second absorbent return path 73 .

As described above, the carbon dioxide recovery system 100c of the present embodiment includes the decarbonated gas discharge path 70, the decarbonated gas cooler 71, and the third gas-liquid separator 72. The decarbonated gas discharge path 70 discharges the decarbonated gas, which is exhaust gas from which CO ₂ has been removed, from the carbon dioxide absorption unit 1 . The decarbonated gas cooling unit 71 is provided in the decarbonated gas discharge path 70 and cools the discharged decarbonated gas. The third gas-liquid separator 72 is provided in the decarbonated gas discharge path 70 on the downstream side of the decarbonated gas cooling unit 71 in the direction in which the decarbonated gas flows, and separates the absorbent contained in the discharged decarbonated gas. do.

As a result, it is possible to avoid the discharge of the absorbing liquid accompanying the discharge of the decarbonated gas, and it is possible to suppress consumption of the absorbing liquid.

A carbon dioxide recovery system 100d of the fifth embodiment includes a first pressure reducing section 8, as shown in FIG. The first decompression unit 8 is provided in the carbon dioxide discharge path 24 immediately downstream of the absorbent regeneration unit 2, and reduces the internal pressure of the absorbent regeneration unit 2 and the rich absorbent heating unit 44, etc., provided upstream thereof. reduce The first decompression unit 8 is composed of, for example, a blower.

By lowering the pressure in the absorbent regeneration unit 2 in this way, the CO ₂ separation can be promoted and the CO ₂ recovery rate can be improved.

When the first decompression unit 8 is provided in the carbon dioxide recovery system 100a of the second embodiment (FIG. 2), the upstream side of the carbon dioxide post-treatment unit 6 (that is, the carbon dioxide post-treatment unit 6 and the absorbent regeneration unit 2 It is preferable that the first decompression unit 8 is positioned between . As a result, the pressure in the absorbent regeneration unit 2 can be reduced, and the pressure in the carbon dioxide cooling unit 61 is increased, so that the condensation of the absorbent contained in CO ₂ can be promoted.

As explained above, the carbon dioxide recovery system 100d of the present embodiment includes the first pressure reducing section 8 . The first pressure reducing section 8 is provided in the carbon dioxide discharge path 24 and reduces the pressure inside the absorbent regeneration section 2 .

As a result, the separation of CO ₂ from the rich absorbent in the absorbent regeneration unit 2 can be promoted, and the recovery rate of CO ₂ can be improved.

The carbon dioxide recovery system 100e of the sixth embodiment includes a carbon dioxide cleaning section 9 provided downstream of the carbon dioxide post-treatment section 6, as shown in FIG.

The carbon dioxide cleaning section 9 is configured as a scrubber, and a cleaning liquid for cleaning CO ₂ is stored therein. The CO ₂ from the carbon dioxide post-treatment section 6 is supplied to the inside of the cleaning liquid stored by the carbon dioxide cleaning section 9 .

By using the bubbling phenomenon in this way, the absorbent remaining in the discharged CO ₂ can be removed more cleanly. The CO ₂ purified by the carbon dioxide cleaning unit 9 is suitable for providing for greenhouse horticulture (for example, photosynthetic growth promotion of plants) such as glass chambers and vinyl greenhouses.

With this configuration, it is possible to cleanly remove the absorbent remaining in the CO ₂ , and to reliably avoid discharge of the absorbent that is harmful to the environment.

By the way, the carbon dioxide cleaning unit 9 may include a carbon filter 91 . The carbon filter 91 is used to remove moisture such as water vapor contained in the CO ₂ cleaned with the cleaning liquid. The carbon filter 91 is arranged, for example, in the vicinity of the exhaust port through which the CO ₂ washed with the cleaning liquid stored in the carbon dioxide washing unit 9 is discharged.

The carbon filter 91 is preferably housed in a nonmetallic container such as vinyl chloride having excellent corrosion resistance. As a result, it is possible to avoid electrolytic corrosion caused by the absorption of water by the carbon filter 91, and to improve the durability of the container.

As a result, the CO ₂ that has passed through the carbon dioxide cleaning unit 9 becomes dry CO ₂ from which _the remaining absorbent and moisture are completely removed. The humidity in the facility can be preferably maintained.

In addition, the carbon dioxide cleaning unit 9 is not limited to the above configuration, and may be configured only with the carbon filter 91 instead of the scrubber, for example. In this case, the carbon filter 91 removes the absorbent and water remaining in the CO ₂ discharged from the second gas-liquid separator 62 .

The carbon dioxide recovery system 100f of the seventh embodiment further includes a second pressure reduction section 90 provided downstream of the carbon dioxide cleaning section 9 (exit of the carbon dioxide cleaning section 9). The second decompression unit 90 is composed of, for example, a blower or the like, and decompresses the pressure inside the carbon dioxide cleaning unit 9 .

Accordingly, by lowering the pressure in the carbon dioxide cleaning unit 9, the number of bubbles generated in the carbon dioxide cleaning unit 9 can be increased, and the cleaning power against CO ₂ can be improved. That is, it is possible to more reliably avoid the discharge of the absorbing liquid accompanying the discharge of CO ₂ .

Next, the 1st modification of the said embodiment is demonstrated. FIG. 8 is a schematic diagram showing the configuration of the carbon dioxide recovery system of the first modified example. In the description of this modified example, the same or similar members as those of the above-described embodiment may be denoted by the same reference numerals in the drawings, and the description thereof may be omitted.

As shown in FIG. 8, the carbon dioxide recovery system 100g of this modification includes a rich absorbent branch path 48 that connects the rich absorbent circulation path 41 and the lean absorbent circulation path 42 .

The rich absorbent branch path 48 is formed from a pipe through which the rich absorbent flows. The rich absorbent branch path 48 is branched from the rich absorbent circulation path 41 so as to recirculate part of the rich absorbent discharged from the carbon dioxide absorption section 1 into the carbon dioxide absorption section 1. there is

The rich absorbent branch path 48 includes, for example, the rich absorbent circulation path 41 on the upstream side of the rich absorbent pump 45 and the lean absorbent circulation path 42 between the lean absorbent pump 46 and the lean absorbent cooling unit 47 . , connect.

In the configuration of this modified example, the recirculation of the lean absorbent can improve the degree of saturation of CO ₂ in the rich absorbent discharged from the carbon dioxide absorber 1 . That is, it is possible to improve the CO ₂ absorption performance of the carbon dioxide absorption part 1 .

Next, the 2nd modification of the said embodiment is demonstrated. FIG. 9 is a schematic diagram showing the configuration of the carbon dioxide recovery system of the second modified example. In the description of this modified example, the same or similar members as those of the above-described embodiment may be denoted by the same reference numerals in the drawings, and the description thereof may be omitted.

The carbon dioxide recovery system 100h of this modified example further includes a sub carbon dioxide supply unit 80 . The sub-carbon dioxide supply unit 80 stores CO ₂ separated from the rich absorbent by the absorbent regeneration unit 2, and supplies the stored CO ₂ for greenhouse horticulture such as glass chambers and vinyl greenhouses.

The sub carbon dioxide supply unit 80 is used to supply CO ₂ to the greenhouse gardening or the like when the engine 10 is stopped. That is, the carbon dioxide reservoir 81 functions as a CO ₂ reservoir when the engine 10 is in operation, and functions as a CO ₂ supply source when the engine 10 is stopped.

The sub carbon dioxide supply unit 80 mainly includes a carbon dioxide storage unit 81, a heat storage unit 82, a third pressure reducing unit 83, and a second carbon dioxide washing unit 84, as shown in FIG.

The carbon dioxide reservoir 81 is composed of, for example, a dissolution tank that dissolves CO ₂ in a liquid such as water by pressurization or the like and stores it. That is, the carbon dioxide reservoir 81 stores CO ₂ in the form of an aqueous solution. However, it is not limited to this, and may be stored by other appropriate methods.

Power for pressurizing CO ₂ and/or water in the carbon dioxide reservoir 81 may be obtained, for example, from the engine 10 or may be obtained from another power source. However, when power is obtained from another power source, it is preferable to stop the other power in conjunction with stopping the engine 10 .

The carbon dioxide reservoir 81 is connected to the second carbon dioxide discharge port 25 formed above the absorbent regeneration part 2 via a carbon dioxide reservoir path 85, as shown in FIG. The carbon dioxide storage part 81 stores part of the CO ₂ separated from the rich absorbent by the absorbent regeneration part 2 .

The carbon dioxide storage path 85 has a configuration similar to that of the carbon dioxide discharge path 24 and is formed of piping through which CO ₂ flows. The carbon dioxide storage path 85 guides the CO ₂ separated in the absorbent regeneration unit 2 to the sub carbon dioxide supply unit 80 . The carbon dioxide storage path 85 is not limited to being connected to the second carbon dioxide discharge port 25 , and may be connected to the carbon dioxide discharge path 24 so as to branch from the carbon dioxide discharge path 24 , for example.

The heat storage unit 82 is composed of a heat storage tank or the like that stores heat generated by the operation of the engine 10 or the like. The heat stored in the heat storage section 82 is used, for example, to heat the carbon dioxide storage section 81 . The heat storage unit 82 separates the carbonated water stored in the carbon dioxide storage unit 81 into water and CO ₂ by heating the carbon dioxide storage unit 81 .

Heat is stored in the heat storage unit 82 when the engine 10 is in operation. Heating of the carbon dioxide storage portion 81 in the heat storage portion 82 is performed when CO ₂ is supplied by the sub carbon dioxide supply portion 80 after the engine 10 is stopped. That is, the heat accumulator 82 functions as a heat accumulator when the engine 10 is in operation, and functions as a heater when the engine 10 is stopped.

The third decompression section 83 has the same configuration as the second decompression section 90 in the above-described embodiment, and is composed of, for example, a blower. The third pressure reducing unit 83 is provided in a second carbon dioxide discharge path 86 connected to the top of the carbon dioxide storage unit 81, reduces the pressure in the carbon dioxide storage unit 81, and reduces the pressure in the carbon dioxide storage unit 81. is accelerated, and the heat storage unit 82 heats the carbon dioxide storage unit 81 to promote the discharge of the CO ₂ that has been decomposed in the carbon dioxide storage unit 81 .

The second carbon dioxide cleaning section 84 has the same configuration and functions as the carbon dioxide cleaning section 9 . The second carbon dioxide washing section 84 is composed of, for example, the carbon filter 92 capable of absorbing the absorbent and moisture, as described above, and removes the absorbent and moisture contained in the CO ₂ from the carbon dioxide storage section 81 .

In the carbon dioxide recovery system 100h configured as described above, during operation of the engine 10, part of the CO ₂ separated by the absorbent regeneration unit 2 is released to the outside (gardening facilities, etc.) via the carbon dioxide discharge path 24. A part of the CO ₂ discharged to and separated in the absorbent regeneration unit 2 is stored in the sub carbon dioxide supply unit 80 .

As a result, even after the engine 10 is stopped under conditions where the supply of heat or the like is not required, the sub carbon dioxide supply unit 80 can provide CO ₂ to greenhouse gardening or the like.

Although the preferred embodiments and modifications of the present invention have been described above, the above configuration can be modified as follows, for example.

The control device 5 may be provided separately from the ECU included in the engine 10 .

In the first absorbent return path 63, the pump 64 for pumping the absorbent to the carbon dioxide absorption part 1 may be omitted. Similarly, in the second absorbent return path 73, the pump 74 for pumping the absorbent to the carbon dioxide absorber 1 may be omitted.

In the carbon dioxide cleaning section 9, by providing a nozzle or the like for injecting CO ₂ , the number of bubbles generated in the cleaning liquid stored in the carbon dioxide cleaning section 9 can be increased.

In the absorbent circulation section 4 , a lean absorbent reflux path may be provided for returning part of the lean absorbent discharged from the absorbent regeneration section 2 to the upstream side of the rich absorbent heating section 44 . As a result, the recovery rate of CO ₂ in the absorbent regeneration unit 2 can be improved.

An exhaust gas purifier that purifies nitrogen oxides (NOx) contained in the exhaust gas may be provided in the exhaust gas supply path 30 between the engine 10 and the carbon dioxide absorber 1 . In this case, since the exhaust gas from which nitrogen oxides have been removed is supplied to the carbon dioxide absorber 1, it is possible to prevent the absorption performance of the absorbent from deteriorating due to the interaction between the acidic components contained in the exhaust gas and the absorbent. can do.

Coolers having substantially the same structure can be used for the carbon dioxide cooling section 61 and the decarbonated gas cooling section 71 .

A decarbonated gas branch path may be formed to introduce part of the decarbonated gas discharged from the carbon dioxide absorption part 1 from the decarbonated gas discharge path 70 to the exhaust gas supply path 30 . Thereby, CO ₂ in the exhaust gas can be sufficiently recovered.

A temperature detection unit may be provided in the carbon dioxide absorption unit 1 and the absorbent regeneration unit 2 . The flow rate of cooling water supplied to the exhaust gas cooling section 34, the lean absorbing liquid cooling section 47, the rich absorbing liquid heating section 44, etc. may be controlled based on the detection results of these temperature detecting sections.

A check valve may be provided at the exhaust gas inlet 11 of the carbon dioxide absorber 1 to prevent the absorbent from flowing back to the exhaust gas supply path 30 . In this case, the height at which the exhaust gas pressure increasing device 33 is arranged may be arbitrary.

1 carbon dioxide absorption part (absorption part)
5 Control Device 10 Engine 30 Exhaust Gas Supply Path 33 Exhaust Gas Boosting Device (Boosting Device)
100 carbon dioxide capture system

Claims (10)

A carbon dioxide recovery system for separating and recovering carbon dioxide from an engine exhaust gas,
an absorption unit that causes an absorption liquid to absorb carbon dioxide contained in the exhaust gas;
an exhaust gas supply path for supplying the exhaust gas to the absorbing section;
a booster for boosting the exhaust gas;
A carbon dioxide capture system comprising: A carbon dioxide recovery system according to claim 1,
A carbon dioxide recovery system comprising a control device for controlling the amount of pressurization of the exhaust gas by the pressurization device. The carbon dioxide recovery system according to claim 1 or 2,
A carbon dioxide recovery system, comprising: a first cooling section provided in the exhaust gas supply path for cooling the exhaust gas supplied to the absorbing section. A carbon dioxide recovery system according to any one of claims 1 to 3,
A carbon dioxide recovery system comprising an absorbent discharge path for discharging the absorbent from the absorption unit. A carbon dioxide recovery system according to claim 4,
A carbon dioxide recovery system comprising a regeneration unit that separates carbon dioxide from the absorbent discharged from the absorbent discharge path and regenerates the absorbent. A carbon dioxide recovery system according to claim 5,
A carbon dioxide recovery system comprising an absorbent reflux path for refluxing the absorbent from which carbon dioxide has been separated by the regeneration section into the absorbent section. A carbon dioxide recovery system according to claim 6,
A carbon dioxide recovery system, comprising: a second cooling section that is provided in the absorbent reflux path and that cools the absorbent flowing back to the absorbent section. A carbon dioxide recovery system according to any one of claims 1 to 7,
A carbon dioxide recovery system, comprising an exhaust gas discharge path for discharging a second exhaust gas, which is the exhaust gas from which carbon dioxide has been removed, from the absorber. A carbon dioxide capture system according to claim 8,
A carbon dioxide recovery system, comprising: a third cooling section provided in the exhaust gas discharge path for cooling the second exhaust gas discharged from the absorbing section. A carbon dioxide capture system according to claim 9,
A second cooling unit is provided in the exhaust gas discharge path on the downstream side of the third cooling unit in the direction in which the second exhaust gas flows, and separates the absorbent contained in the second exhaust gas discharged from the absorbing unit. 1. A carbon dioxide recovery system comprising an absorbent separation unit.

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