Ammonia abatement system, floating body, and ammonia abatement method

Abstract

To secure absorptivity of ammonia in purging.SOLUTION: An ammonia detoxification system includes: a first tank for storing an absorption liquid capable of absorbing ammonia; a first introduction line capable of introducing purge gas containing ammonia and inert gas to the first tank; a first absorption promoting part for promoting absorption of ammonia by the absorption liquid in the first tank; a first liquid discharge line capable of discharging liquid from a liquid phase of the first tank; a first gas exhaust line capable of exhausting gas from a gas phase of the first tank; a second tank provided independently from the first tank; an upper connection line for connecting a gas phase of an upper part of the first tank and an upper part of the second tank; and a pressure control valve which is provided in the connection line, and is openable / closable according to pressure of the gas phase of the first tank.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to an ammonia abatement system, a floating body, and an ammonia abatement method. [Background technology]

[0002] In floating bodies such as ships, when ammonia is used as fuel for the main engine, it is expected that the ammonia will be switched between other fuels such as heavy oil. When such a fuel switch is performed or when some kind of trouble occurs in the main engine, it is necessary to discharge the ammonia from the piping of the fuel system by purging the piping with an inert gas such as nitrogen. However, ammonia may have an impact on the surrounding environment, so it is not desirable to release the ammonia discharged from the piping during the purging process directly into the water or atmosphere surrounding the floating body.

[0003] Patent Document 1 discloses an ammonia gas abatement system that detoxifies ammonia gas leaked from a refrigerator unit before it is released into the atmosphere. In this abatement system, the ammonia-containing gas is introduced into a closed space such as a scrubber or cooling tower, and is brought into sufficient contact with water, causing the ammonia component to be adsorbed onto the water. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-26555 Summary of the Invention [Problem to be solved by the invention]

[0005] When purging as described above, an inert gas such as nitrogen, which was introduced for purging, is discharged from the piping along with ammonia. For example, if this inert gas is nitrogen, nitrogen is not easily absorbed by water. Therefore, in a detoxification system such as that described in Patent Document 1, the inert gas discharged from the piping is hardly absorbed by water that absorbs ammonia components in a closed space such as a scrubber or cooling tower, and is instead released to the outside. Furthermore, because the flow rate of the inert gas during such purging is high, the large amount of inert gas flowing in may reduce the absorbability of ammonia components in the closed space. Furthermore, a large amount of inert gas flowing in may cause the water supplied into the closed space to flow back upward, which may result in a phenomenon known as flooding.

[0006] The present disclosure has been made to solve the above-mentioned problems, and aims to provide an ammonia detoxification system, a float, and an ammonia detoxification method that can ensure ammonia absorption during purging. [Means for solving the problem]

[0007] In order to solve the above problems, the ammonia detoxification system according to the present disclosure includes a first tank, a first inlet line, a first absorption promoter, a first liquid discharge line, a second gas discharge line, a second tank, an upper connecting line, and a pressure regulating valve. The first tank stores an absorption liquid capable of absorbing ammonia. The first inlet line is capable of introducing a purge gas containing ammonia and an inert gas into the first tank. The first absorption promoter promotes the absorption of ammonia by the absorption liquid in the first tank. The first liquid discharge line is capable of discharging liquid from the liquid phase of the first tank. The first gas discharge line is capable of discharging gas from the gas phase of the first tank. The second tank is provided independently of the first tank. The upper connecting line connects the gas phase at the top of the first tank with the top of the second tank. The pressure regulating valve is provided in the upper connecting line. The pressure regulating valve is capable of opening and closing according to the pressure of the gas phase in the first tank.

[0008] The ammonia abatement system according to the present disclosure comprises a first tank, a first inlet line, a first absorption promoter, a first liquid discharge line, a second gas discharge line, a second tank, a lower connecting line, and a liquid level adjustment valve. The first tank stores an absorption liquid capable of absorbing ammonia. The first inlet line is capable of introducing a purge gas containing ammonia and an inert gas into the first tank. The first absorption promoter promotes the absorption of ammonia by the absorption liquid in the first tank. The first liquid discharge line is capable of discharging liquid from the liquid phase of the first tank. The first gas discharge line is capable of discharging gas from the gas phase of the first tank. The second tank is provided independently of the first tank. The lower connecting line connects the liquid phase in the lower part of the first tank with the lower part of the second tank. The liquid level adjustment valve is provided in the lower connecting line. The liquid level adjustment valve is capable of opening and closing according to the pressure of the gas phase in the first tank.

[0009] The float according to the present disclosure comprises a float body and the above-described ammonia abatement system.

[0010] The ammonia detoxification method according to the present disclosure is an ammonia detoxification method for an ammonia detoxification system as described above, and includes the steps of storing an absorption liquid, introducing a purge gas, absorbing ammonia, and transferring a gas phase gas. The storing absorption liquid step stores an absorption liquid capable of absorbing ammonia in a first tank. The introducing purge gas step introduces a purge gas containing ammonia and an inert gas into the first tank. The absorbing ammonia step causes the absorption liquid to absorb ammonia contained in the purge gas introduced into the first tank. The transferring gas phase gas step transfers the gas phase in the upper part of the first tank to the second tank when the gas phase in the first tank reaches a predetermined reference pressure or higher. [Effects of the Invention]

[0011] According to the ammonia abatement system, float, and ammonia abatement method of the present disclosure, it is possible to ensure ammonia absorption during purging. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a side view of a floating body equipped with an ammonia abatement system according to an embodiment of the present disclosure. [Figure 2] 1 is a diagram showing the configuration of an ammonia detoxification system according to a first embodiment of the present disclosure. [Figure 3] 1 is a flowchart of an ammonia detoxification method according to a first embodiment of the present disclosure. [Figure 4] FIG. 2 is a diagram showing a step of storing an absorbing liquid in the first embodiment of the present disclosure. [Figure 5] FIG. 2 is a diagram showing a step of introducing a purge gas and a step of absorbing ammonia in the first embodiment of the present disclosure. [Figure 6] FIG. 2 is a diagram showing a step of transferring a gas phase in the first embodiment of the present disclosure. [Figure 7] FIG. 10 is a diagram illustrating a step of terminating the introduction of a purge gas in the first embodiment of the present disclosure. [Figure 8] FIG. 2 is a diagram showing a step of discharging a gas phase in the first embodiment of the present disclosure. [Figure 9] FIG. 9 is a diagram showing a state subsequent to FIG. 8 in the step of discharging the gas phase in the first embodiment of the present disclosure. [Figure 10] FIG. 10 is a diagram showing a case where a liquid phase is discharged into a second wastewater tank in the step of discharging the liquid phase in the first embodiment of the present disclosure. [Figure 11] FIG. 10 is a diagram showing a case where the liquid phase is landed in the step of discharging the liquid phase in the first embodiment of the present disclosure. [Figure 12] FIG. 10 is a diagram showing a case where the liquid phase is treated in an ammonia compound removal section in the step of discharging the liquid phase in the first embodiment of the present disclosure. [Figure 13] FIG. 2 is a diagram showing the configuration of an ammonia detoxification system according to a second embodiment of the present disclosure. [Figure 14] 10 is a flowchart of an ammonia detoxification method according to a second embodiment of the present disclosure. [Figure 15] FIG. 10 is a diagram showing a step of storing an absorbing liquid in a second embodiment of the present disclosure. [Figure 16] FIG. 10 is a diagram showing a step of introducing a purge gas and a step of absorbing ammonia in a second embodiment of the present disclosure. [Figure 17] FIG. 10 is a diagram showing a step of transferring a gas phase in a second embodiment of the present disclosure. [Figure 18] FIG. 10 is a diagram showing a step of terminating the introduction of a purge gas in the second embodiment of the present disclosure. [Figure 19] FIG. 10 is a diagram showing a step of discharging a gas phase in the second embodiment of the present disclosure. [Figure 20] FIG. 20 is a diagram showing a state subsequent to FIG. 19 in the step of discharging the gas phase in the second embodiment of the present disclosure. [Figure 21] FIG. 10 is a diagram showing a case where the liquid phase is discharged into a second wastewater tank in the step of discharging the liquid phase in the second embodiment of the present disclosure. [Figure 22]FIG. 10 is a diagram showing a case where the liquid phase is landed in the step of discharging the liquid phase in the second embodiment of the present disclosure. [Figure 23] FIG. 10 is a diagram showing a case where the liquid phase is treated in an ammonia component removal section in the step of discharging the liquid phase in the first embodiment of the present disclosure. [Figure 24] FIG. 1 is a diagram showing the configuration of an ammonia detoxification system according to a modified example of the first and second embodiments of the present disclosure. [Figure 25] FIG. 10 is a diagram showing the configuration of an ammonia detoxification system according to another modified example of the first and second embodiments of the present disclosure. [Figure 26] FIG. 10 is a diagram showing the configuration of an ammonia detoxification system according to still another modified example of the first and second embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an ammonia detoxification system, a floating body, and an ammonia detoxification method according to an embodiment of the present disclosure will be described with reference to FIGS. First Embodiment (Overall structure of the floating body) As shown in FIG. 1 , a float 1 according to a first embodiment of the present disclosure includes a float main body 2, a superstructure 4, a combustion device 8, and an ammonia abatement system 100A. The float 1 according to the first embodiment will be described as a ship capable of navigation using a main engine or the like. The type of ship that the float 1 is used for is not limited to a specific type of ship. Examples of ship types that the float 1 can be used for include a liquefied gas carrier, a ferry, a roll-on / roll-off ship, a car carrier, and a passenger ship. While the first embodiment will be described with reference to a ship, the float 1 is not limited to a ship, and may also be an FSU (Floating Storage Unit), FSRU (Floating Storage and Regasification Unit), or the like that is not capable of navigation using a main engine or the like.

[0014] The floating body 2 is formed so as to float on seawater. The floating body 2 has a pair of side panels 5A, 5B and a bottom 6 that form its outer hull. The side panels 5A, 5B are provided with a pair of side shell plates that form the port and starboard sides, respectively. The bottom 6 is provided with a bottom shell plate that connects the side panels 5A, 5B. The pair of side panels 5A, 5B and the bottom 6 give the outer hull of the floating body 2 a U-shape in a cross section perpendicular to the bow-stern direction FA.

[0015] The floating body main body 2 further comprises an upper deck 7, which is a full-length deck located at the topmost level. The superstructure 4 is formed on this upper deck 7. Accommodation areas and the like are provided within the superstructure 4. In the floating body 1 of this first embodiment, for example, a cargo space (not shown) for carrying cargo is provided closer to the bow 2a in the bow-stern direction FA than the superstructure 4.

[0016] The combustion device 8 is a device that generates thermal energy by burning fuel, and is provided inside the floating body main body 2. Examples of the combustion device 8 include an internal combustion engine used as the main engine for propelling the floating body 1, an internal combustion engine used in a power generation facility that supplies electricity on board, and a boiler that generates steam as a working fluid. The combustion device 8 used as the main engine in the floating body 1 of this embodiment is capable of switching between ammonia and other fuels different from ammonia, such as heavy oil, as fuel. A fuel system (not shown) that supplies fuel is connected to the combustion device 8. Ammonia and other fuels circulate through the fuel system.

[0017] When switching the fuel for the combustion device 8 from ammonia to another fuel or when performing maintenance, ammonia remaining in a piping system including the fuel system of the combustion device 8 is replaced with an inert gas (purge gas) such as nitrogen, a process known as purging. Here, the ammonia remaining in the piping system may be liquefied ammonia or ammonia gas. To perform purging, an inert gas supply device (not shown) is connected to the piping system. The inert gas supply device is capable of supplying an inert gas to the piping system. Note that the inert gas may be any gas that does not chemically react when in contact with ammonia, and an example of such a gas is nitrogen. When the inert gas supply device supplies an inert gas from an inert gas supply source (not shown) to the piping system, the ammonia in the piping system is pushed out by the inert gas. As a result, a purge gas containing ammonia (liquefied ammonia, ammonia gas) and the inert gas is discharged from the piping system.

[0018] (Configuration of ammonia abatement system) FIG. 2 is a diagram showing the configuration of an ammonia detoxification system according to the first embodiment of the present disclosure. 2, the ammonia detoxification system 100A includes at least a purge gas introduction section 10, a first tank 20A, a second tank 30A, an exhaust section 40, a drainage section 50, a first wastewater tank 60, a second wastewater tank 70, an ammonia component removal section 80, and a pressure adjustment section 110. The ammonia detoxification system 100A detoxifies the ammonia contained in the purge gas discharged from the piping system when the ammonia in the piping system is purged.

[0019] The purge gas introduction section 10 introduces the purge gas discharged from the piping system of the combustion device 8 during purging to the ammonia abatement system 100A. The purge gas introduction section 10 introduces the gas components of the purge gas, which have been gas-liquid separated in a knockout drum (not shown), to the ammonia abatement system 100A. The purge gas flowing through this purge gas introduction section 10 has different concentrations of ammonia and inert gas during the initial, middle, and final stages of purging. For example, during the initial stage of purging, mainly ammonia gas flows through the purge gas introduction section 10. During the intermediate stage of purging, a mixed gas of ammonia gas and inert gas flows through the purge gas introduction section 10. During the final stage of purging, substantially only inert gas flows through the purge gas introduction section 10.

[0020] The purge gas introduction section 10 includes a main introduction line 11, a tank introduction line 12, and a bypass line 13. The main introduction line 11 is connected to the piping system of the combustion device 8. To the main introduction line 11, purge gas discharged from the piping system of the combustion device 8 during purging is introduced. The tank introduction line 12 and the bypass line 13 are provided by branching off from the main introduction line 11 into two systems.

[0021] The tank introduction line 12 sends purge gas to the first tank 20A and the second tank 30A. The tank introduction line 12 includes a main pipe 14, a first introduction line 15, and a second introduction line 16. The main pipe 14 is connected to the main introduction line 11. The main pipe 14 includes an on-off valve 14V. The on-off valve 14V is capable of opening and closing the flow path in the main pipe 14.

[0022] The first inlet line 15 and the second inlet line 16 are provided branching off into two systems from the main pipe 14. The downstream end of the first inlet line 15 is connected to the top of the first tank 20A. The downstream end of the second inlet line 16 is connected to the top of the second tank 30A. An on-off valve 15V is provided in the first inlet line 15. The on-off valve 15V is capable of opening and closing the flow path in the first inlet line 15. An on-off valve 16V is provided in the second inlet line 16. The on-off valve 16V is capable of opening and closing the flow path in the second inlet line 16.

[0023] The bypass line 13 releases the purge gas introduced from the main inlet line 11 directly into the atmosphere without sending it to the first tank 20A or the second tank 30A. The bypass line 13 runs from the main inlet line 11, bypassing the first tank 20A and the second tank 30A, and is connected to an atmosphere release line 43, which will be described later. An on-off valve 13V that can open and close the flow path in the bypass line 13 is provided midway along the bypass line 13.

[0024] The first tank 20A includes a tank body 21 and a first absorption promoter 22A. The tank body 21 has a hollow structure and stores therein an absorbing liquid L capable of absorbing ammonia. A water intake pipe 27 is connected to the tank body 21, which takes in fresh water or seawater from the outside as the absorbing liquid L. As a result, a liquid in a liquid phase containing the absorbing liquid L is stored in the lower part of the tank body 21. A gas in a gas phase is stored above the liquid phase in the tank body 21. A purge gas is introduced into the tank body 21 through the main inlet line 11, the main piping 14, and the first inlet line 15. The ammonia component contained in the purge gas introduced into the tank body 21 is absorbed by the absorbing liquid L. As a result, the liquid in the liquid phase in the tank body 21 contains the absorbing liquid L and the ammonia component.

[0025] A liquid level gauge 28 and a pressure gauge 29 are provided inside the tank body 21 of the first tank 20A. The liquid level gauge 28 detects the liquid level of the liquid phase inside the tank body 21. The pressure gauge 29 detects the pressure of the gas phase inside the tank body 21. The liquid level gauge 28 and the pressure gauge 29 output their respective detection data to a control device (not shown) described below.

[0026] The first absorption promoter 22A promotes the absorption of ammonia by the absorption liquid L in the first tank 20A. In this embodiment, the first absorption promoter 22A includes a first circulation line 23, a spray 24, a circulation pump 25, and a heat exchanger 26. One end of the first circulation line 23 is connected to the lower part of the first tank 20A. The other end of the first circulation line 23 is disposed in the gas phase at the upper part of the first tank 20A. The spray 24 is provided at the other end of the first circulation line 23 within the first tank 20A. The circulation pump 25 and the heat exchanger 26 are provided midway along the first circulation line 23. The circulation pump 25 draws the liquid phase within the first tank 20A into the first circulation line 23 and circulates it to the gas phase at the upper part of the first tank 20A. The heat exchanger 26 cools the liquid phase drawn into the first circulation line 23 and removes the heat of reaction generated when ammonia dissolves in the absorption liquid L. The liquid phase sucked into the first circulation line 23 is sprayed into the gas phase in the upper part of the first tank 20A through the spray 24. As a result, the absorption liquid L contained in the liquid phase comes into contact with the ammonia in the gas phase in the first tank 20A, and the absorption of ammonia is promoted.

[0027] The second tank 30A is provided independently of the first tank 20A. The second tank 30A includes a tank body 31 and a second absorption promoter 32A. The tank body 31 has a hollow structure and stores therein an absorbing liquid L capable of absorbing ammonia. To this end, an intake pipe 37 is connected to the tank body 31, which takes in fresh water or seawater from the outside as the absorbing liquid L. As a result, a liquid phase containing the absorbing liquid L is stored in the lower part of the tank body 31. In the tank body 31, a gas phase is stored above the liquid phase. A purge gas is introduced into the tank body 31 through the main inlet line 11, the main piping 14, and the second inlet line 16. The ammonia component contained in the purge gas introduced into the tank body 31 is absorbed by the absorbing liquid L. As a result, the liquid phase in the tank body 31 contains the absorbing liquid L and the ammonia component.

[0028] The second absorption promoter 32A promotes the absorption of ammonia by the absorption liquid L in the second tank 30A. In this embodiment, the second absorption promoter 32A includes a second circulation line 33, a spray 34, a circulation pump 35, and a heat exchanger 36. One end of the second circulation line 33 is connected to the lower part of the second tank 30A. The other end of the second circulation line 33 is disposed in the gas phase at the upper part of the second tank 30A. The spray 34 is provided at the other end of the second circulation line 33 within the second tank 30A. The circulation pump 35 and the heat exchanger 36 are provided midway along the second circulation line 33. The circulation pump 35 draws the liquid phase in the second tank 30A into the second circulation line 33 and circulates it to the gas phase at the upper part of the second tank 30A. The heat exchanger 36 cools the liquid phase drawn into the second circulation line 33 and removes the heat of reaction generated when ammonia dissolves in the absorption liquid L. The liquid phase sucked into the second circulation line 33 is sprayed into the gas phase in the upper part of the second tank 30A through the spray 34. As a result, the absorption liquid L contained in the liquid phase comes into contact with the ammonia in the gas phase in the second tank 30A, and the absorption of ammonia is promoted.

[0029] A liquid level gauge 38 and a pressure gauge 39 are provided inside the tank body 31 of the second tank 30A. The liquid level gauge 38 detects the liquid level of the liquid phase inside the tank body 31. The pressure gauge 39 detects the pressure of the gas phase inside the tank body 31. The liquid level gauge 38 and the pressure gauge 39 output their respective detection data to a control device (not shown) described below.

[0030] The exhaust unit 40 includes a first gas exhaust line 41, a second gas exhaust line 42, and an open-to-atmosphere line 43. The first gas discharge line 41 is capable of discharging gas from the gas phase of the first tank 20A. One end of the first gas discharge line 41 is connected to an upper portion of the tank body 21 of the first tank 20A. The other end of the first gas discharge line 41 is connected to an atmosphere release line 43. A flow rate adjustment valve 41V is provided in the first gas discharge line 41. The flow rate adjustment valve 41V is capable of adjusting the flow rate of the gas phase in the first tank 20A that is discharged through the first gas discharge line 41.

[0031] The second gas discharge line 42 is capable of discharging gas from the gas phase of the second tank 30A. One end of the second gas discharge line 42 is connected to an upper portion of the tank body 31 of the second tank 30A. The other end of the second gas discharge line 42 is connected to an atmosphere vent line 43. A flow rate adjustment valve 42V is provided in the second gas discharge line 42. The flow rate adjustment valve 42V is capable of adjusting the flow rate of the gas phase in the second tank 30A that is discharged through the second gas discharge line 42.

[0032] The atmosphere release line 43 releases to the atmosphere the gas phase gas discharged from the first gas discharge line 41 and the second gas discharge line 42, and the purge gas discharged through the bypass line 13. As the atmosphere release line 43, for example, a vent post or a funnel 9 (see FIG. 1) provided on the upper deck 7 of the floating body main body 2 can be used.

[0033] A dilution line 44 is connected to the atmosphere vent line 43. The dilution line 44 is capable of introducing dilution gas into the atmosphere vent line 43 to reduce the ammonia concentration in the gas phase discharged through the atmosphere vent line 43. An example of the dilution gas is outside air (air) taken in from the outside through the dilution line 44. The dilution line 44 is provided with a dilution fan 45 that can adjust the flow rate of the dilution gas sent into the atmosphere vent line 43.

[0034] The drainage section 50 includes a first liquid drainage line 51 , a second liquid drainage line 52 , a drainage line 55 , and a third liquid drainage line 53 .

[0035] The first liquid discharge line 51 is capable of discharging liquid from the liquid phase of the first tank 20A. The first liquid discharge line 51 is shared with a part of the first circulation line 23. Specifically, the first liquid discharge line 51 is shared with the first circulation line 23 from a part 23a where the first circulation line 23 is connected to the lower part of the tank body 21 to a part 23j where one end of a drain line 55 is connected downstream of the circulation pump 25.

[0036] The second liquid discharge line 52 is capable of discharging liquid from the liquid phase of the second tank 30A. The second liquid discharge line 52 is provided to connect a lower portion of the tank body 31 of the second tank 30A to a portion of the first liquid discharge line 51 upstream of the circulation pump 25 and the heat exchanger 26. An on-off valve 52V is provided in the second liquid discharge line 52. The on-off valve 52V is capable of opening and closing the flow path in the second liquid discharge line 52.

[0037] The third liquid discharge line 53 is provided to connect a lower portion of the tank body 21 of the first tank 20A to a portion of the second circulation line 33 upstream of the circulation pump 35 and the heat exchanger 36. An on-off valve 53V is provided in the third liquid discharge line 53. The on-off valve 53V is capable of opening and closing the flow path in the third liquid discharge line 53.

[0038] The drainage line 55 is connected to the first liquid discharge line 51 at portion 23j. The other end of the drainage line 55 is connected to branch pipes 56, 57. The branch pipe 56 is connected to a first wastewater tank 60. The branch pipe 57 is connected to a second wastewater tank 70. An on-off valve 56V is provided in the branch pipe 56. The on-off valve 56V is capable of opening and closing the flow path in the branch pipe 56. An on-off valve 57V is provided in the branch pipe 57. The on-off valve 57V is capable of opening and closing the flow path in the branch pipe 57.

[0039] The first wastewater tank 60 and the second wastewater tank 70 are capable of storing liquids discharged through the drainage section 50 from the first tank 20A and the second tank 30A, respectively. The first wastewater tank 60 is connected to the ammonia component removal section 80 via a drainage line 61. A pump 62 is provided in the middle of the drainage line 61. The liquid temporarily stored in the first wastewater tank 60 is transferred to the ammonia component removal section 80 through the drainage line 61 by operating the pump 62.

[0040] The ammonia component removal section 80 removes the ammonia component contained in the absorption solution L. When seawater or fresh water is introduced into the first tank 20A and the second tank 30A as the absorption solution L, the absorption solution L that has absorbed ammonia is transferred from the first tank 20A and the second tank 30A to the ammonia component removal section 80 via the first wastewater tank 60.

[0041] The ammonia component removal unit 80 removes ammonia components contained in the absorbing solution L, for example, by a denitrification reaction using sodium hypochlorite. The ammonia component removal unit 80 includes, for example, an electrolysis unit 81 and a denitrification reaction unit 83. The electrolysis unit 81 generates a seawater electrolyte containing sodium hypochlorite by electrolyzing seawater taken in from outside the ship. Specifically, the electrolysis unit 81 electrolyzes the introduced seawater by placing a positive electrode and a negative electrode (not shown) in the introduced seawater and applying a voltage between the positive electrode and the negative electrode. Sodium hypochlorite is generated from the seawater by this electrolysis.

[0042] The denitrification reaction unit 83 reacts a mixture of the absorption solution L that has absorbed ammonia with the seawater electrolyte produced in the electrolysis unit 81. The denitrification reaction unit 83 mixes and reacts the seawater electrolyte produced by electrolysis with the absorption solution L introduced from the first tank 20A and the second tank 30A. More specifically, as shown in formula (1), the denitrification reaction unit 83 reacts ammonia (2NH3) contained in the absorption solution L that has absorbed ammonia with sodium hypochlorite (3NaClO) in the seawater electrolyte in an acidic environment to decompose them into nitrogen (N2), sodium chloride (3NaCl), and water (3H2O). 2NH3+3NaClO⇒N2+3NaCl+3H2O...(1)

[0043] Nitrogen produced by the denitrification reaction in the denitrification reaction section 83 is released into the atmosphere, for example, via a funnel 9 extending from the upper deck 7. On the other hand, sodium chloride and water produced by the denitrification reaction are discharged as treated water from a discharge section 89 connected to the ammonia component removal section 80 into the seawater surrounding the floating body 2.

[0044] In addition, a landing line 68 is provided branching off from the discharge line 61. The landing line 68 is connected to the discharge line 61 between the pump 62 and the ammonia component removal section 80. The landing line 68 is configured to be able to land the liquid phase stored in the first wastewater tank 60. The liquid phase landed at a port or the like through the landing line 68 is not regenerated within the floating body 2, but is disposed of at a land facility.

[0045] The second wastewater tank 70 temporarily stores the liquid discharged from the first tank 20A and the second tank 30A through the drainage section 50. In this first embodiment, the liquid stored in the second wastewater tank 70 may be used as ammonia liquid for denitration to be used in a denitration device (not shown). The denitration device performs denitration treatment on the exhaust gas discharged from the combustion device 8. This denitration device is installed midway through an exhaust pipe (not shown) through which the exhaust gas is discharged from the combustion device 8. The denitration device is a selective catalytic reduction (SCR) denitration device that converts nitrogen oxides contained in the exhaust gas into nitrogen and water using a catalyst. In this case, the ammonia liquid for denitration is preferably adjusted to a predetermined ammonia concentration (e.g., approximately 25%) required for use as a reducing agent in the denitration device. The liquid discharged from the first tank 20A and the second tank 30A through the drainage section 50 has an increased ammonia concentration by absorbing ammonia. Such a liquid with an increased ammonia concentration can be suitably used as ammonia liquid for denitration.

[0046] (Configuration of pressure adjustment unit) The pressure adjusting section 110 includes an upper connecting line 111 and a pressure adjusting valve 112 . The upper connection line 111 connects the gas phase at the top of the first tank 20A with the top of the second tank 30A.

[0047] The pressure regulating valve 112 is provided midway along the upper connecting line 111. The pressure regulating valve 112 is capable of opening and closing the flow path in the upper connecting line 111 in accordance with the gas phase pressure of the first tank 20A. The pressure regulating valve 112 is opened and closed in accordance with the gas phase pressure of the first tank 20A detected by a pressure gauge 29. The operation of the pressure regulating valve 112 is automatically controlled by a control device (not shown).

[0048] The pressure regulating valve 112 is controlled to open when the gas phase pressure of the first tank 20A is higher than the gas phase pressure of the second tank 30A and the gas phase pressure of the first tank 20A reaches or exceeds a preset reference pressure. When the pressure regulating valve 112 opens in a state in which the gas phase pressure of the first tank 20A is higher than the gas phase pressure of the second tank 30A, the gas phase of the first tank 20A is connected to the upper part of the second tank 30A. This reduces the gas phase pressure of the first tank 20A.

[0049] (Ammonia detoxification method) Next, the ammonia detoxification method for a floating body according to the first embodiment of the present disclosure will be described with reference to the drawings. FIG. 3 is a flowchart of the ammonia detoxification method according to the first embodiment of the present disclosure. As shown in FIG. 3, the ammonia detoxification method S10 of the first embodiment includes a step S11 of storing an absorption liquid L, a step S12 of introducing a purge gas, a step S13 of absorbing ammonia, a step S14 of checking the pressure of the gas phase, a step S15 of transferring the gas phase gas, a step S16 of checking the completion of purging, a step S17 of terminating the introduction of the purge gas, a step S17A of bringing ammonia into a gas-liquid equilibrium state, a step S18 of discharging the gas phase gas, and a step S19 of discharging the liquid phase liquid.

[0050] FIG. 4 is a diagram showing a step of storing an absorbing liquid in the first embodiment of the present disclosure. In step S11 of storing the absorption liquid L, prior to purging by feeding an inert gas into a piping system including a fuel system of the combustion device 8, the absorption liquid L is stored in a first tank 20A as shown in FIG. 4. Fresh water or seawater is taken in from outside the first tank 20A through a water intake pipe 27 to form the absorption liquid L. The absorption liquid L is stored until the liquid level detected by a liquid level gauge 28 reaches a preset liquid level. In step S11, the absorption liquid L may also be stored in a second tank 30A. Furthermore, the on-off valves 13V, 14V, and 15V, the pressure regulating valve 112, the flow rate regulating valves 41V and 42V, and the on-off valves 52V, 53V, 56V, and 57V are all kept closed.

[0051] FIG. 5 is a diagram showing a step of introducing a purge gas and a step of absorbing ammonia in the first embodiment of the present disclosure. In the step S12 of introducing a purge gas, when an inert gas is sent into the piping system to perform purging, a purge gas containing ammonia and an inert gas is introduced into the first tank 20A. To do this, as shown in Fig. 5, only the on-off valves 14V and 15V of the tank introduction line 12 are opened. Then, the purge gas is introduced into the first tank 20A from the main introduction line 11 through the main pipe 14 of the tank introduction line 12 and the first introduction line 15.

[0052] In the step S13 of absorbing ammonia, the ammonia contained in the purge gas introduced into the first tank 20A is absorbed into the absorption liquid L. At this time, in the first absorption promotion section 22A, the circulation pump 25 is operated to suck the liquid in the liquid phase in the first tank 20A into the first circulation line 23, and the liquid is sprayed from the spray 24 into the gas phase in the upper part of the first tank 20A. As a result, the absorption liquid L contained in the liquid phase comes into contact with the ammonia in the gas phase in the first tank 20A, and the absorption of the ammonia is promoted. Note that this step S13 may be performed in parallel with the step S12 of introducing the purge gas.

[0053] Incidentally, when purging the piping system, a large amount of inert gas is fed. For this reason, the purge gas is fed successively into the first tank 20A. The ammonia contained in the purge gas fed into the first tank 20A is absorbed by the absorption liquid L. Accordingly, the concentration of the inert gas, which is difficult to absorb by the absorption liquid L, increases in the gas phase of the first tank 20A. At this time, the inside of the first tank 20A becomes a closed space, and the pressure of the gas phase gradually increases.

[0054] In step S14 of checking the pressure of the gas phase, the pressure of the gas phase in the first tank 20A is detected by the pressure gauge 29 at preset time intervals while steps S12 and S13 are continuing. The data of the pressure of the gas phase detected by the pressure gauge 29 is output to a control device (not shown). When the control device acquires data on the gas phase pressure detected by the pressure gauge 29, it determines whether the detected pressure is equal to or greater than a preset reference pressure. As a result, if the detected pressure of the gas phase in the first tank 20A is lower than the reference pressure ("No" in step S14), steps S12 and S13 are continued as is. On the other hand, if the detected pressure of the gas phase in the first tank 20A is equal to or higher than the reference pressure ("Yes" in step S14), the process proceeds to step S15.

[0055] FIG. 6 is a diagram showing a step of transferring a gas phase in the first embodiment of the present disclosure. In step S15 of transferring the gas phase, the pressure regulating valve 112 is opened under the control of the control device, as shown in FIG. 6. This step S15 is performed in a state where the gas phase pressure in the first tank 20A detected by the pressure gauge 29 is higher than the gas phase pressure in the second tank 30A detected by the pressure gauge 39. Then, the gas in the gas phase in the first tank 20A is transferred into the second tank 30A through the upper connecting line 111. This reduces the gas phase pressure in the first tank 20A. As a result, the first tank 20A can receive the entire amount of purge gas that is sequentially fed in. By continuing step S13 in parallel with step S15, ammonia contained in the purge gas sent into the first tank 20A is absorbed by the absorption liquid L. Accordingly, the concentration of the inert gas increases in the gas phase of the first tank 20A. Furthermore, if the absorption liquid L is stored in the second tank 30A in step S15, ammonia contained in the gas transferred from the first tank 20A to the second tank 30A is absorbed by the absorption liquid L. On the other hand, if the absorption liquid L is not stored in the second tank 30A in step S15, the pressure of the gas phase in the second tank 30A can be reduced to approximately atmospheric pressure, and a larger amount of gas can be received from the first tank 20A.

[0056] In step S16 of checking the completion of purging, the control device checks whether the supply of inert gas that has been carried out for purging the piping system has been completed. As a result, if it is not possible to confirm that the supply of the inert gas has not finished and that the purging has finished ("No" in step S16), the process returns to step S14. On the other hand, if it can be confirmed that the supply of the inert gas has ended and the purging has ended ("Yes" in step S16), the process proceeds to step S17.

[0057] FIG. 7 is a diagram showing a step of terminating the introduction of the purge gas in the first embodiment of the present disclosure. In step S17 of terminating the introduction of the purge gas, as shown in FIG. 7, after it is confirmed that the supply of the inert gas to the piping system has ended, the on-off valves 14V and 15V are closed and the on-off valve 13V of the bypass line 13 is opened. At the end of the purging of the piping system, the purge gas is essentially an inert gas with a low ammonia content. Therefore, the on-off valve 13V is opened and the purge gas is released to the atmosphere from the atmosphere release line 43 via the bypass line 13. This reduces the pressure in the piping system. After the pressure in the piping system has sufficiently reduced, the on-off valve 13V is closed.

[0058] In step S17, if the pressure regulating valve 112 is open, the pressure regulating valve 112 is closed. Furthermore, in the first absorption promotion section 22A, the liquid in the liquid phase in the first tank 20A continues to be circulated to the spray 24, and the liquid continues to be dispersed into the gas phase in the upper part of the first tank 20A. In step S17A, which brings ammonia into gas-liquid equilibrium, ammonia is brought into gas-liquid equilibrium between the gas and liquid phases in the first tank 20A. As the liquid dispersion continues into the gas phase at the top of the first tank 20A, the absorbing solution L contained in the liquid phase in the first tank 20A comes into contact with the ammonia in the gas phase in the first tank 20A, gradually decreasing the ammonia concentration. The gas phase and the absorbing solution (liquid phase) in the first tank 20A attempt to reach gas-liquid equilibrium. That is, as the ammonia solubility in the absorbing solution increases, the ammonia concentration in the gas phase also gradually increases. On the other hand, as the ammonia concentration in the gas phase decreases, the ammonia in the liquid phase is released due to the partial pressure difference and sequentially supplied to the gas phase, thereby decreasing the ammonia solubility in the liquid phase. When the ammonia concentrations in the gas and liquid phases in the first tank 20A reach equilibrium and ammonia reaches gas-liquid equilibrium in the first tank 20A, the process proceeds to step S18. The gas-liquid equilibrium state of ammonia may be determined, for example, by directly measuring the pressure and temperature in the first tank 20A or the ammonia concentration in the first tank 20A.

[0059] FIG. 8 is a diagram showing a step of discharging the gas phase in the first embodiment of the present disclosure. In step S18 of discharging the gas phase, as shown in FIG. 8, the circulation pump 25 is stopped, halting the circulation of the absorption liquid L (liquid phase) in the first tank 20A and the spraying from the spray 24. Furthermore, the flow control valve 41V is opened, and the gas in the gas phase of the first tank 20A is discharged into the atmosphere through the first gas discharge line 41 and the atmosphere release line 43. If the ammonia concentration in the gas discharged through the atmosphere release line 43 is high, the flow control valve 41V reduces the flow rate of the purge gas discharged from the first tank 20A to the first gas discharge line 41. This reduces the ammonia concentration in the gas discharged through the atmosphere release line 43. Furthermore, by operating the dilution fan 45 and increasing the flow rate of the diluted gas sent into the atmosphere release line 43, the ammonia concentration in the gas phase discharged through the atmosphere release line 43 can be further reduced. After the gas in the gas phase of the first tank 20A is discharged, the flow control valve 41V is closed.

[0060] FIG. 9 is a diagram showing a state subsequent to FIG. 8 in the step of discharging gas phase gas in the first embodiment of the present disclosure. Furthermore, in step S18 of discharging the gas phase, as shown in FIG. 9, the flow control valve 42V is opened, and the gas phase gas in the second tank 30A is discharged into the atmosphere through the second gas discharge line 42 and the atmosphere vent line 43. At this time, if the ammonia concentration in the gas phase discharged through the atmosphere vent line 43 is high, the flow control valve 42V reduces the flow rate of the purge gas discharged from the second tank 30A to the second gas discharge line 42. This reduces the ammonia concentration in the gas discharged through the atmosphere vent line 43. Furthermore, by operating the dilution fan 45 and increasing the flow rate of the diluted gas sent into the atmosphere vent line 43, the ammonia concentration in the gas discharged through the atmosphere vent line 43 can be further reduced. After the gas phase gas in the second tank 30A is discharged, the flow control valve 42V is closed.

[0061] Fig. 10 is a diagram showing a case where the liquid phase liquid is discharged into a second wastewater tank in the step of discharging the liquid phase liquid in the first embodiment of the present disclosure. Fig. 11 is a diagram showing a case where the liquid phase liquid is landed in the step of discharging the liquid phase liquid in the first embodiment of the present disclosure. Fig. 12 is a diagram showing a case where the liquid phase liquid is treated in an ammonia component removal unit in the step of discharging the liquid phase liquid in the first embodiment of the present disclosure. In step S19 of discharging the liquid phase, when the ammonia concentration in the liquid phase remaining in first tank 20A exceeds a preset reference concentration, the liquid phase is discharged by drainage unit 50. Note that step S19 may be performed before step S18 of discharging the liquid phase, or may be performed in parallel with step S18. In step S19, circulation pump 25 is operated. As a result, as shown in FIGS. 10 to 12, the liquid phase liquid in first tank 20A is drained through first liquid discharge line 51 and drain line 55. Furthermore, if liquid phase liquid remains in second tank 30A, opening / closing valve 52V causes the liquid phase liquid in second tank 30A to be drained through second liquid discharge line 52, first liquid discharge line 51, and drain line 55.

[0062] At this time, when fresh water is introduced into the first tank 20A and the second tank 30A, the on-off valve 56V is closed and the on-off valve 57V is opened, as shown in Fig. 10. As a result, the liquid phase remaining in the first tank 20A and the second tank 30A is discharged into the second wastewater tank 70 and can be used as a reducing agent in the denitration device. Furthermore, when seawater or fresh water is introduced into the first tank 20A and the second tank 30A, no further processing is performed on the floating body 1, and as shown in Figure 11, by opening the on-off valve 56V and closing the on-off valve 57V, the liquid phase may be stored in the first wastewater tank 60 and then landed via the landing line 68. Furthermore, when seawater or fresh water is being introduced into the first tank 20A and the second tank 30A, the on-off valve 56V is opened and the on-off valve 57V is closed. As a result, as shown in Fig. 12, the liquid phase liquid containing seawater remaining in the first tank 20A and the second tank 30A is sent to the ammonia component removal section 80 via the first wastewater tank 60. The liquid phase liquid is subjected to ammonia component removal treatment in the ammonia component removal section 80, and then discharged into the ocean (discharged overboard) from the discharge section 89.

[0063] Prior to performing step S18 of discharging the gas phase gas, the absorption liquid L may be stored again in the first tank 20A and the second tank 30A in the same manner as in step S11 after performing step S19 of discharging the liquid phase liquid. This can increase the efficiency of absorption of ammonia in the gas phase gas remaining in the first tank 20A and the second tank 30A.

[0064] (Action and effect) In the ammonia detoxification system 100A, the floating body 1, and the ammonia detoxification method S10 of the above embodiment, the first tank 20A and the second tank 30A, which is provided independently of the first tank 20A, are connected by an upper connecting line 111. When the pressure regulating valve 112 provided on the upper connecting line 111 is opened in response to the gas phase pressure of the first tank 20A, the gas in the gas phase at the top of the first tank 20A is transferred to the top of the second tank 30A. This reduces the gas phase pressure of the first tank 20A. This allows the first tank 20A to further receive the purge gas that subsequently flows in. As a result, the first tank 20A can receive a large amount of purge gas that flows in during purging, allowing more ammonia to be absorbed. Furthermore, in the first tank 20A, the ammonia contained in the purge gas is absorbed by the absorption liquid L, and the ammonia concentration in the gas phase is reduced before the gas phase is discharged. Thus, the first tank 20A performs batch processing, rather than continuous processing, in which the ammonia contained in the introduced purge gas is absorbed while the gas containing the absorbed ammonia is continuously discharged. Therefore, there is no need to install an absorption tower or the like downstream of the first tank 20A, and the purge gas can be efficiently treated while sufficiently absorbing ammonia. This also prevents the occurrence of a phenomenon known as flooding, in which water supplied to a closed space such as an absorption tower flows back upward due to the flow of inert gas.

[0065] In the above embodiment, when the pressure of the gas phase in the first tank 20A exceeds a preset reference pressure, the pressure regulating valve 112 opens, sending the gas in the gas phase in the first tank 20A to the upper part of the second tank 30A. Therefore, the inert gas sequentially introduced into the first tank 20A prevents the pressure of the gas phase in the first tank 20A from excessively increasing above the reference pressure. This prevents a decrease in the ammonia absorbability of the absorption liquid L in the first tank 20A.

[0066] In the above embodiment, the second tank 30A includes a second introduction line 16 and a second absorption promoter 32A. As a result, the second tank 30A can also absorb ammonia contained in the purge bath, just like the first tank 20A. Therefore, if the first tank 20A is unable to absorb ammonia for some reason, the second tank 30A can absorb ammonia instead of the first tank 20A. This increases the redundancy of the ammonia abatement system 100A.

[0067] In the above embodiment, the ammonia detoxification system 100A includes the flow rate adjustment valve 41V. As a result, when the ammonia concentration is high in the gas phase gas of the first tank 20A discharged through the first gas discharge line 41, the flow rate of the gas phase can be reduced by the flow rate adjustment valve 41V. Therefore, the ammonia concentration in the gas discharged from the first gas discharge line 41 can be reduced.

[0068] In the above embodiment, the first absorption promoter 22A including the spray 24 can promote absorption of ammonia contained in the purge gas by the absorption liquid L in the first tank 20A.

[0069] In addition, in the above embodiment, the liquid phase in the first tank 20A is circulated to the first absorption promotion section 22A by the first circulation line 23, whereby the absorption liquid L can be effectively utilized and the absorption of ammonia by the absorption liquid L can be efficiently performed.

[0070] In the above embodiment, the heat exchanger 26 cools the liquid phase sucked into the first circulation line 23, thereby removing the heat of reaction generated when ammonia dissolves in the absorption liquid L.

[0071] Second Embodiment Next, a second embodiment of the ammonia detoxification system and ammonia detoxification method according to the present disclosure will be described. The second embodiment described below differs from the first embodiment only in that the ammonia detoxification system includes a liquid level adjustment unit 120 instead of the pressure adjustment unit 110. Therefore, the same parts as those in the first embodiment will be described with the same reference numerals, and duplicated explanations will be omitted. (Configuration of ammonia abatement system) FIG. 13 is a diagram showing the configuration of an ammonia detoxification system according to the second embodiment of the present disclosure. 13, the ammonia detoxification system 100B mainly includes a purge gas introduction section 10, a first tank 20A, a second tank 30A, an exhaust section 40, a drainage section 50, a first wastewater tank 60, a second wastewater tank 70, an ammonia component removal section 80, and a liquid level adjustment section 120. The ammonia detoxification system 100B detoxifies the ammonia contained in the purge gas that is discharged from the piping system when the ammonia in the piping system is purged.

[0072] The purge gas introduction section 10 introduces the purge gas discharged from the piping system of the combustion device 8 during purging to the ammonia abatement system 100B. The purge gas introduction section 10 introduces the gas components of the purge gas, which have been gas-liquid separated in a knockout drum (not shown), to the ammonia abatement system 100B. The purge gas flowing through this purge gas introduction section 10 has different concentrations of ammonia and inert gas during the initial, middle, and final stages of purging. For example, during the initial stage of purging, mainly ammonia gas flows through the purge gas introduction section 10. During the intermediate stage of purging, a mixed gas of ammonia gas and inert gas flows through the purge gas introduction section 10. During the final stage of purging, substantially only inert gas flows through the purge gas introduction section 10.

[0073] The purge gas introduction section 10 includes a main introduction line 11, a tank introduction line 12, and a bypass line 13. The main introduction line 11 is connected to the piping system of the combustion device 8. To the main introduction line 11, purge gas that is discharged from the piping system of the combustion device 8 during purging is introduced. The tank introduction line 12 and the bypass line 13 are provided by branching off from the main introduction line 11 into two systems.

[0074] The tank introduction line 12 sends purge gas to the first tank 20A and the second tank 30A. The tank introduction line 12 includes a main pipe 14, a first introduction line 15, and a second introduction line 16. The main pipe 14 is connected to the main introduction line 11. The main pipe 14 includes an on-off valve 14V. The on-off valve 14V is capable of opening and closing the flow path in the main pipe 14.

[0075] The first inlet line 15 and the second inlet line 16 are provided branching off into two systems from the main pipe 14. The downstream end of the first inlet line 15 is connected to the top of the first tank 20A. The downstream end of the second inlet line 16 is connected to the top of the second tank 30A. An on-off valve 15V is provided in the first inlet line 15. The on-off valve 15V is capable of opening and closing the flow path in the first inlet line 15. An on-off valve 16V is provided in the second inlet line 16. The on-off valve 16V is capable of opening and closing the flow path in the second inlet line 16.

[0076] The bypass line 13 releases the purge gas introduced from the main inlet line 11 directly into the atmosphere without sending it to the first tank 20A or the second tank 30A. The bypass line 13 runs from the main inlet line 11, bypassing the first tank 20A and the second tank 30A, and is connected to an atmosphere release line 43, which will be described later. An on-off valve 13V that can open and close the flow path in the bypass line 13 is provided midway along the bypass line 13.

[0077] The first tank 20A includes a tank body 21 and a first absorption promoter 22A. The tank body 21 has a hollow structure, and stores therein an absorbing liquid L capable of absorbing ammonia. To this end, an intake pipe 27 is connected to the tank body 21, which takes in fresh water or seawater from the outside as the absorbing liquid L. As a result, a liquid phase containing the absorbing liquid L is stored in the lower part of the tank body 21. In the tank body 21, a gas phase is stored above the liquid phase. A purge gas is introduced into the tank body 21 through the main inlet line 11, the main piping 14, and the first inlet line 15. The ammonia component contained in the purge gas introduced into the tank body 21 is absorbed by the absorbing liquid L. As a result, the liquid phase in the tank body 21 contains the absorbing liquid L and the ammonia component.

[0078] A liquid level gauge 28 and a pressure gauge 29 are provided inside the tank body 21 of the first tank 20A. The liquid level gauge 28 detects the liquid level of the liquid phase inside the tank body 21. The pressure gauge 29 detects the pressure of the gas phase inside the tank body 21. The liquid level gauge 28 and the pressure gauge 29 output their respective detection data to a control device (not shown) described below.

[0079] The first absorption promoter 22A promotes the absorption of ammonia by the absorption liquid L in the first tank 20A. In this embodiment, the first absorption promoter 22A includes a first circulation line 23, a spray 24, a circulation pump 25, and a heat exchanger 26. One end of the first circulation line 23 is connected to the lower part of the first tank 20A. The other end of the first circulation line 23 is disposed in the gas phase at the upper part of the first tank 20A. The spray 24 is provided at the other end of the first circulation line 23 within the first tank 20A. The circulation pump 25 and the heat exchanger 26 are provided midway along the first circulation line 23. The circulation pump 25 draws the liquid in the liquid phase in the first tank 20A into the first circulation line 23 and circulates it to the gas phase at the upper part of the first tank 20A. The heat exchanger 26 cools the liquid phase drawn into the first circulation line 23 and removes the heat of reaction generated when ammonia dissolves in the absorption liquid L. The liquid phase liquid sucked into the first circulation line 23 is sprayed into the gas phase in the upper part of the first tank 20A through the spray 24. As a result, the absorption liquid L contained in the liquid comes into contact with the ammonia in the gas phase in the first tank 20A, and the absorption of ammonia is promoted.

[0080] The second tank 30A is provided independently of the first tank 20A. The second tank 30A includes a tank body 31 and a second absorption promoter 32A. The tank body 31 has a hollow structure and stores therein an absorbing liquid L capable of absorbing ammonia. To this end, an intake pipe 37 is connected to the tank body 31, which takes in fresh water or seawater from the outside as the absorbing liquid L. As a result, a liquid in a liquid phase containing the absorbing liquid L is stored in the lower part of the tank body 31. In the tank body 31, a gas in a gas phase is stored above the liquid phase. A purge gas is introduced into the tank body 31 through the main inlet line 11, the main piping 14, and the second inlet line 16. The ammonia component contained in the purge gas introduced into the tank body 31 is absorbed by the absorbing liquid L. As a result, the liquid phase in the tank body 31 contains the absorbing liquid L and the ammonia component.

[0081] The second absorption promoter 32A promotes the absorption of ammonia by the absorption liquid L in the second tank 30A. In this embodiment, the second absorption promoter 32A includes a second circulation line 33, a spray 34, a circulation pump 35, and a heat exchanger 36. One end of the second circulation line 33 is connected to the lower part of the second tank 30A. The other end of the second circulation line 33 is disposed in the gas phase at the upper part of the second tank 30A. The spray 34 is provided at the other end of the second circulation line 33 within the second tank 30A. The circulation pump 35 and the heat exchanger 36 are provided midway along the second circulation line 33. The circulation pump 35 draws the liquid in the liquid phase in the second tank 30A into the second circulation line 33 and circulates it to the gas phase at the upper part of the second tank 30A. The heat exchanger 36 cools the liquid drawn into the second circulation line 33 and removes the heat of reaction generated when ammonia dissolves in the absorption liquid L. The liquid phase sucked into the second circulation line 33 is sprayed into the gas phase in the upper part of the second tank 30A through the spray 34. As a result, the absorption liquid L contained in the liquid comes into contact with the ammonia in the gas phase in the second tank 30A, and the absorption of ammonia is promoted.

[0082] A liquid level gauge 38 and a pressure gauge 39 are provided inside the tank body 31 of the second tank 30A. The liquid level gauge 38 detects the liquid level of the liquid phase inside the tank body 31. The pressure gauge 39 detects the pressure of the gas phase inside the tank body 31. The liquid level gauge 38 and the pressure gauge 39 output their respective detection data to a control device (not shown) described below.

[0083] The exhaust unit 40 includes a first gas exhaust line 41, a second gas exhaust line 42, and an open-to-atmosphere line 43. The first gas discharge line 41 is capable of discharging gas from the gas phase of the first tank 20A. One end of the first gas discharge line 41 is connected to an upper portion of the tank body 21 of the first tank 20A. The other end of the first gas discharge line 41 is connected to an atmosphere release line 43. A flow rate adjustment valve 41V is provided in the first gas discharge line 41. The flow rate adjustment valve 41V is capable of adjusting the flow rate of the gas phase in the first tank 20A that is discharged through the first gas discharge line 41.

[0084] The second gas discharge line 42 is capable of discharging gas from the gas phase of the second tank 30A. One end of the second gas discharge line 42 is connected to an upper portion of the tank body 31 of the second tank 30A. The other end of the second gas discharge line 42 is connected to an atmosphere vent line 43. A flow rate adjustment valve 42V is provided in the second gas discharge line 42. The flow rate adjustment valve 42V is capable of adjusting the flow rate of gas in the second tank 30A that is discharged through the second gas discharge line 42.

[0085] The atmosphere release line 43 releases to the atmosphere the gas phase gas discharged from the first gas discharge line 41 and the second gas discharge line 42, and the purge gas discharged through the bypass line 13. As the atmosphere release line 43, for example, a vent post or a funnel 9 (see FIG. 1) provided on the upper deck 7 of the floating body main body 2 can be used.

[0086] A dilution line 44 is connected to the atmosphere vent line 43. The dilution line 44 is capable of introducing dilution gas into the atmosphere vent line 43 to reduce the ammonia concentration of the gas discharged through the atmosphere vent line 43. An example of the dilution gas is outside air (air) taken in from the outside through the dilution line 44. The dilution line 44 is provided with a dilution fan 45 that can adjust the flow rate of the dilution gas sent into the atmosphere vent line 43.

[0087] The drainage section 50 includes a first liquid drainage line 51 , a second liquid drainage line 52 , a drainage line 55 , and a third liquid drainage line 53 .

[0088] The first liquid discharge line 51 is capable of discharging liquid from the liquid phase of the first tank 20A. The first liquid discharge line 51 is shared with a part of the first circulation line 23. Specifically, the first liquid discharge line 51 is shared with the first circulation line 23 from a part 23a where the first circulation line 23 is connected to the lower part of the tank body 21 to a part 23j where one end of a drain line 55 is connected downstream of the circulation pump 25.

[0089] The second liquid discharge line 52 is capable of discharging liquid from the liquid phase of the second tank 30A. The second liquid discharge line 52 is provided to connect a lower portion of the tank body 31 of the second tank 30A to a portion of the first liquid discharge line 51 upstream of the circulation pump 25 and the heat exchanger 26. An on-off valve 52V is provided in the second liquid discharge line 52. The on-off valve 52V is capable of opening and closing the flow path in the second liquid discharge line 52.

[0090] The third liquid discharge line 53 is provided to connect a lower portion of the tank body 21 of the first tank 20A to a portion of the second circulation line 33 upstream of the circulation pump 35 and the heat exchanger 36. An on-off valve 53V is provided in the third liquid discharge line 53. The on-off valve 53V is capable of opening and closing the flow path in the third liquid discharge line 53.

[0091] The drainage line 55 is connected to the first liquid discharge line 51 at portion 23j. The other end of the drainage line 55 is connected to branch pipes 56 and 57. The branch pipe 56 is connected to a first wastewater tank 60. The branch pipe 57 is connected to a second wastewater tank 70. An on-off valve 56V is provided in the branch pipe 56. The on-off valve 56V is capable of opening and closing the flow path in the branch pipe 56. An on-off valve 57V is provided in the branch pipe 57. The on-off valve 57V is capable of opening and closing the flow path in the branch pipe 57.

[0092] The first wastewater tank 60 and the second wastewater tank 70 are capable of storing liquids discharged through the drainage section 50 from the first tank 20A and the second tank 30A, respectively. The first wastewater tank 60 is connected to the ammonia component removal section 80 via a drainage line 61. A pump 62 is provided in the middle of the drainage line 61. The liquid temporarily stored in the first wastewater tank 60 is transferred to the ammonia component removal section 80 through the drainage line 61 by operating the pump 62.

[0093] The ammonia component removal section 80 is used when seawater is introduced into the first tank 20A and the second tank 30A as the absorption solution L. When seawater is introduced into the first tank 20A and the second tank 30A as the absorption solution L, the absorption solution L (seawater) that has absorbed ammonia is transferred from the first tank 20A and the second tank 30A via the first wastewater tank 60 to the ammonia component removal section 80. The ammonia component removal section 80 removes the ammonia component contained in the absorption solution L using sodium hypochlorite obtained by electrolyzing the transferred seawater.

[0094] The ammonia component removal unit 80 includes an electrolysis unit 81 and a denitrification reaction unit 83. The electrolysis unit 81 generates a seawater electrolyte containing sodium hypochlorite by electrolyzing seawater. Specifically, the electrolysis unit 81 electrolyzes the seawater by placing a positive electrode and a negative electrode (not shown) in the introduced seawater and applying a voltage between the positive electrode and the negative electrode. This electrolysis generates sodium hypochlorite from the seawater.

[0095] The denitrification reaction unit 83 reacts a mixture of the absorption solution L that has absorbed ammonia with the seawater electrolyte produced in the electrolysis unit 81. The denitrification reaction unit 83 mixes and reacts the seawater electrolyte produced by electrolysis with the absorption solution L introduced from the first tank 20A and the second tank 30A. More specifically, as shown in formula (1), the denitrification reaction unit 83 reacts ammonia (2NH3) contained in the absorption solution L that has absorbed ammonia with sodium hypochlorite (3NaClO) in the seawater electrolyte in an acidic environment to decompose them into nitrogen (N2), sodium chloride (3NaCl), and water (3H2O). 2NH3+3NaClO⇒N2+3NaCl+3H2O...(1)

[0096] Nitrogen produced by the denitrification reaction in the denitrification reaction section 83 is released into the atmosphere, for example, via a funnel 9 extending from the upper deck 7. On the other hand, sodium chloride and water produced by the denitrification reaction are discharged as treated water from a discharge section 89 connected to the ammonia component removal section 80 into the seawater surrounding the floating body 2.

[0097] In addition, a landing line 68 is provided branching off from the discharge line 61. The landing line 68 is connected to the discharge line 61 between the pump 62 and the ammonia component removal section 80. The landing line 68 is configured to be able to land the liquid phase stored in the first wastewater tank 60. The liquid phase landed at a port or the like through the landing line 68 is not regenerated within the floating body 2, but is disposed of at a land facility.

[0098] The second wastewater tank 70 temporarily stores the liquid discharged from the first tank 20A and the second tank 30A through the drainage section 50. In this embodiment, the liquid stored in the second wastewater tank 70 may be used as ammonia liquid for denitration to be used in a denitration device (not shown). The denitration device performs denitration treatment on the exhaust gas discharged from the combustion device 8. This denitration device is installed in the exhaust pipe (not shown) through which the exhaust gas is discharged from the combustion device 8. The denitration device is a selective catalytic reduction denitration device (SCR) that converts nitrogen oxides contained in the exhaust gas into nitrogen and water using a catalyst. In this case, the ammonia liquid for denitration is preferably adjusted to a predetermined ammonia concentration (e.g., approximately 25%) required for use as a reducing agent in the denitration device. The liquid in the liquid phase discharged from the first tank 20A and the second tank 30A through the drainage section 50 has an increased ammonia concentration by absorbing ammonia. Such a liquid with an increased ammonia concentration can be suitably used as ammonia liquid for denitration.

[0099] (Configuration of liquid level adjustment unit) The liquid level adjusting unit 120 includes a lower connecting line 121 and a liquid level adjusting valve 122 . The lower connection line 121 connects the liquid phase at the lower part of the first tank 20A with the lower part of the second tank 30A.

[0100] The liquid level adjustment valve 122 is provided midway through the lower connecting line 121. The liquid level adjustment valve 122 is capable of opening and closing the flow path in the lower connecting line 121 in accordance with the gas phase pressure of the first tank 20A. The liquid level adjustment valve 122 is opened and closed in accordance with the gas phase pressure of the first tank 20A detected by a pressure gauge 29. The operation of the liquid level adjustment valve 122 is automatically controlled by a control device (not shown).

[0101] The level adjustment valve 122 is controlled to open when the pressure of the gas phase in the first tank 20A reaches or exceeds a preset reference pressure while the liquid level in the first tank 20A is higher than the liquid level in the second tank 30A. When the level adjustment valve 122 opens while the liquid level in the first tank 20A is higher than the liquid level in the second tank 30A, the liquid phase in the first tank 20A is connected to the lower part of the second tank 30A. This lowers the liquid level in the first tank 20A, reducing the pressure of the gas phase in the first tank 20A.

[0102] Furthermore, the liquid level adjustment valve 122 is controlled to open when the pressure of the gas phase in the first tank 20A falls below a preset lower limit pressure while the liquid level in the first tank 20A is lower than the liquid level in the second tank 30A. When the liquid level in the first tank 20A is lower than the liquid level in the second tank 30A and the pressure of the gas phase in the first tank 20A falls below a preset lower limit pressure, opening the liquid level adjustment valve 122 causes the liquid phase in the second tank 30A to return to the bottom of the first tank 20A through the lower connection line 121. This causes the liquid level in the first tank 20A to rise.

[0103] (Ammonia detoxification method) Next, a method for detoxifying ammonia from a floating body according to a second embodiment will be described with reference to the drawings. FIG. 14 is a flowchart of an ammonia detoxification method according to the second embodiment of the present disclosure. As shown in FIG. 14, the ammonia detoxification method S20 of the second embodiment includes a step S21 of storing an absorption liquid L, a step S22 of introducing a purge gas, a step S23 of absorbing ammonia, a step S24 of checking the pressure of the gas phase, a step S25 of transferring the liquid phase, a step S26 of checking the completion of purging, a step S27 of completing the introduction of the purge gas, a step S27A of bringing ammonia into a gas-liquid equilibrium state, a step S28 of discharging the gas phase, and a step S29 of discharging the liquid in the liquid phase.

[0104] FIG. 15 is a diagram showing a step of storing an absorbing liquid in the second embodiment of the present disclosure. In step S21 of storing the absorption liquid L, prior to purging by feeding an inert gas into a piping system including the fuel system of the combustion device 8, the absorption liquid L is stored in the first tank 20A as shown in FIG. 15. Fresh water or seawater is taken in from outside the first tank 20A through a water intake pipe 27 to supply the absorption liquid L. The absorption liquid L is stored until the liquid level detected by a liquid level gauge 28 reaches a preset liquid level. In step S21, the absorption liquid L may also be stored in the second tank 30A. In this case, however, the liquid level of the absorption liquid L in the second tank 30A detected by a liquid level gauge 38 is set to be lower than the liquid level of the absorption liquid L in the first tank 20A. In addition, the on-off valves 13V, 14V, and 15V, the liquid level adjustment valve 122, the flow rate adjustment valves 41V and 42V, and the on-off valves 52V, 53V, 56V, and 57V are all kept closed.

[0105] FIG. 16 is a diagram showing a step of introducing a purge gas and a step of absorbing ammonia in the second embodiment of the present disclosure. In the step S22 of introducing a purge gas, when an inert gas is sent into the piping system to perform purging, a purge gas containing ammonia and an inert gas is introduced into the first tank 20A. To do this, as shown in Fig. 16, only the on-off valves 14V and 15V of the tank introduction line 12 are opened. Then, the purge gas is introduced into the first tank 20A from the main introduction line 11 through the main pipe 14 of the tank introduction line 12 and the first introduction line 15.

[0106] In the step S23 of absorbing ammonia, the ammonia contained in the purge gas introduced into the first tank 20A is absorbed into the absorption liquid L. At this time, in the first absorption promotion section 22A, the circulation pump 25 is operated to suck the liquid in the liquid phase in the first tank 20A into the first circulation line 23, and the liquid is sprayed from the spray 24 into the gas phase in the upper part of the first tank 20A. As a result, the absorption liquid L contained in the liquid phase comes into contact with the ammonia in the gas phase in the first tank 20A, and the absorption of the ammonia is promoted. Note that this step S23 may be performed in parallel with the step S22 of introducing the purge gas.

[0107] Incidentally, when purging the piping system, a large amount of inert gas is fed. For this reason, the purge gas is fed successively into the first tank 20A. The ammonia contained in the purge gas fed into the first tank 20A is absorbed by the absorption liquid L. Accordingly, the concentration of the inert gas, which is difficult to absorb by the absorption liquid L, increases in the gas phase of the first tank 20A. At this time, the inside of the first tank 20A becomes a closed space, and the pressure of the gas phase gradually increases.

[0108] In step S24 of checking the pressure of the gas phase, the pressure of the gas phase in the first tank 20A is detected by the pressure gauge 29 at preset time intervals while steps S22 and S23 are continuing. The data of the pressure of the gas phase detected by the pressure gauge 29 is output to a control device (not shown). When the control device acquires data on the gas phase pressure detected by the pressure gauge 29, it determines whether the detected pressure is equal to or greater than a preset reference pressure. As a result, if the detected pressure of the gas phase in the first tank 20A is lower than the reference pressure ("No" in step S24), steps S22 and S23 are continued as is. On the other hand, if the detected pressure of the gas phase in the first tank 20A is equal to or higher than the reference pressure ("Yes" in step S24), the process proceeds to step S25.

[0109] FIG. 17 is a diagram showing a step of transferring a liquid in a liquid phase in the second embodiment of the present disclosure. In step S25 of transferring the liquid phase liquid, the control device controls the level control valve 122 to open, as shown in FIG. 17 . This step S25 is performed when the gas phase pressure of the first tank 20A detected by the pressure gauge 29 is higher than the gas phase pressure of the second tank 30A detected by the pressure gauge 39, and when the liquid phase level of the first tank 20A detected by the level gauge 28 is higher than the liquid phase level of the second tank 30A detected by the level gauge 38. Then, the liquid phase liquid in the first tank 20A is transferred into the second tank 30A through the lower connecting line 121. This reduces the pressure of the gas phase in the first tank 20A. As a result, the first tank 20A can receive the entire amount of purge gas that is sequentially fed into it. By continuing step S23 in parallel with step S25, the ammonia contained in the purge gas fed into the first tank 20A is absorbed by the absorption liquid L. Accordingly, the concentration of the inert gas increases in the gas phase of the first tank 20A.

[0110] In step S26 of checking the completion of purging, the control device checks whether the supply of inert gas that has been carried out for purging the piping system has been completed. As a result, if it is not possible to confirm that the supply of the inert gas has not finished and that the purging has finished ("No" in step S26), the process returns to step S24. On the other hand, if it can be confirmed that the supply of the inert gas has ended and the purging has ended ("Yes" in step S26), the process proceeds to step S27.

[0111] FIG. 18 is a diagram showing a step of terminating the introduction of purge gas in the second embodiment of the present disclosure. In step S27 of terminating the introduction of the purge gas, as shown in FIG. 18, after it is confirmed that the supply of the inert gas to the piping system has ended, the on-off valves 14V and 15V are closed and the on-off valve 13V of the bypass line 13 is opened. At the end of the purging of the piping system, the purge gas is essentially an inert gas with a low ammonia content. Therefore, the on-off valve 13V is opened and the purge gas is released to the atmosphere from the atmosphere release line 43 via the bypass line 13. This reduces the pressure in the piping system. After the pressure in the piping system has sufficiently reduced, the on-off valve 13V is closed.

[0112] In step S27, if the liquid level adjustment valve 122 is open, the liquid level adjustment valve 122 is closed. Furthermore, in the first absorption promotion section 22A, the liquid in the liquid phase in the first tank 20A continues to be circulated to the spray 24, and the liquid continues to be dispersed into the gas phase in the upper part of the first tank 20A. In step S27A, which brings ammonia into gas-liquid equilibrium, ammonia is brought into gas-liquid equilibrium between the gas and liquid phases in the first tank 20A. As the liquid dispersion continues into the gas phase at the top of the first tank 20A, the absorption liquid L contained in the liquid phase in the first tank 20A comes into contact with the ammonia in the gas phase in the first tank 20A, gradually decreasing the ammonia concentration. The gas phase and the absorption liquid (liquid phase) in the first tank 20A attempt to reach gas-liquid equilibrium. That is, as the ammonia solubility in the absorption liquid increases, the ammonia concentration in the gas phase also gradually increases. On the other hand, as the ammonia concentration in the gas phase decreases, the ammonia in the liquid phase is released due to the partial pressure difference and sequentially supplied to the gas phase, thereby decreasing the ammonia solubility in the liquid phase. When the ammonia concentrations in the gas and liquid phases in the first tank 20A reach equilibrium and ammonia reaches gas-liquid equilibrium in the first tank 20A, the process proceeds to step S28. The gas-liquid equilibrium state of ammonia may be determined, for example, by directly measuring the pressure and temperature in the first tank 20A or the ammonia concentration in the first tank 20A.

[0113] FIG. 19 is a diagram showing a step of discharging gas phase gas in the second embodiment of the present disclosure. In step S28 of discharging the gas phase, as shown in FIG. 19, the circulation pump 25 is stopped, halting the circulation of the absorption liquid L (liquid phase) in the first tank 20A and the spraying from the spray 24. Furthermore, the flow control valve 41V is opened, and the gas in the gas phase of the first tank 20A is discharged into the atmosphere through the first gas discharge line 41 and the atmosphere release line 43. If the ammonia concentration in the gas discharged through the atmosphere release line 43 is high, the flow control valve 41V reduces the flow rate of the purge gas discharged from the first tank 20A to the first gas discharge line 41. This reduces the ammonia concentration in the gas discharged through the atmosphere release line 43. Furthermore, by operating the dilution fan 45 and increasing the flow rate of the diluted gas sent into the atmosphere release line 43, the ammonia concentration in the gas discharged through the atmosphere release line 43 can be further reduced. After the gas phase of the first tank 20A is discharged, the flow control valve 41V is closed.

[0114] FIG. 20 is a diagram showing a state subsequent to FIG. 19 in the step of discharging gas phase gas in the second embodiment of the present disclosure. Furthermore, in step S28 of discharging the gas, as shown in FIG. 20 , as the gas in the first tank 20A is released to the atmosphere, the pressure of the gas in the first tank 20A decreases. When the gas pressure in the first tank 20A detected by pressure gauge 29 becomes lower than the gas pressure in the second tank 30A detected by pressure gauge 39 and falls below a preset lower limit pressure, the liquid level adjustment valve 122 is opened. Then, the liquid in the second tank 30A is returned to the lower part of the first tank 20A through the lower connection line 121. By returning the liquid in the second tank 30A to the lower part of the first tank 20A, the liquid level in the first tank 20A rises. This allows the gas liquid in the first tank 20A to be pushed out into the first gas discharge line 41.

[0115] Fig. 21 is a diagram showing a case where the liquid phase liquid is discharged into a second wastewater tank in the step of discharging the liquid phase liquid in the second embodiment of the present disclosure. Fig. 22 is a diagram showing a case where the liquid phase liquid is landed in the step of discharging the liquid phase liquid in the second embodiment of the present disclosure. Fig. 23 is a diagram showing a case where the liquid phase liquid is treated in an ammonia component removal unit in the step of discharging the liquid phase liquid in the second embodiment of the present disclosure. In step S29 of discharging the liquid phase, when the ammonia concentration in the liquid phase remaining in first tank 20A exceeds a preset reference concentration, the liquid phase is discharged by drainage unit 50. Note that step S29 may be performed before step S28 of discharging the gas phase, or may be performed in parallel with step S28. In step S29, the circulation pump 25 is operated. As a result, as shown in FIGS. 21 to 23, the liquid phase liquid in the first tank 20A is drained through the first liquid discharge line 51 and the drain line 55. Furthermore, if liquid remains in the second tank 30A, the on-off valve 52V is opened, whereby the liquid phase liquid in the second tank 30A is drained through the second liquid discharge line 52, the first liquid discharge line 51, and the drain line 55.

[0116] At this time, when fresh water is being introduced into the first tank 20A and the second tank 30A, the on-off valve 56V is closed and the on-off valve 57V is opened, as shown in Fig. 21. As a result, the liquid remaining in the first tank 20A and the second tank 30A is discharged into the second wastewater tank 70 and can be used as a reducing agent in the denitrification device. Furthermore, when fresh water is being introduced into the first tank 20A and the second tank 30A, no further treatment is performed in the floating body 1, and the on-off valve 56V is opened and the on-off valve 57V is closed, as shown in Fig. 22, so that the liquid is stored in the first wastewater tank 60 and then unloaded via the unloading line 68. Furthermore, when seawater is being introduced into the first tank 20A and the second tank 30A, the on-off valve 56V is opened and the on-off valve 57V is closed. As a result, as shown in Fig. 23, the liquid containing seawater remaining in the first tank 20A and the second tank 30A is sent to the ammonia component removal section 80 via the first wastewater tank 60. After the ammonia component is removed from the liquid in the ammonia component removal section 80, the liquid is discharged into the ocean from the discharge section 89. Also, when seawater is being introduced into the first tank 20A and the second tank 30A, as shown in Fig. 22, no further treatment may be performed in the floating body 1, and the liquid may be stored in the first wastewater tank 60 and then landed through the landing line 68.

[0117] Prior to performing step S28 of discharging the gas phase, the absorption liquid L may be stored again in the first tank 20A and the second tank 30A in the same manner as in step S21 after performing step S29 of discharging the liquid phase. This can increase the efficiency of absorption of ammonia in the gas remaining in the first tank 20A and the second tank 30A.

[0118] (Action and effect) According to the above-described configuration, the first tank 20A and the second tank 30A, which is provided independently of the first tank 20A, are connected by the lower connection line 121. When the liquid level control valve 122 opens in response to the pressure of the gas phase in the first tank 20A, the liquid in the lower part of the first tank 20A is transferred to the lower part of the second tank 30A. This increases the volume of the gas phase in the first tank 20A and reduces the pressure of the gas phase. This allows the first tank 20A to further receive the purge gas that subsequently flows in. As a result, the first tank 20A can receive a large amount of purge gas that flows in during purging, allowing it to absorb more ammonia. Furthermore, in the first tank 20A, the ammonia contained in the purge gas is absorbed by the absorption liquid L, and the ammonia concentration in the gas phase is reduced before the gas phase is discharged. Thus, the first tank 20A performs batch processing, rather than continuous processing, in which the ammonia contained in the introduced purge gas is absorbed while the gas containing the absorbed ammonia is continuously discharged. Therefore, there is no need to install an absorption tower or the like downstream of the first tank 20A, and the purge gas can be efficiently treated while sufficiently absorbing ammonia. This also prevents the occurrence of a phenomenon known as flooding, in which water supplied to a closed space such as an absorption tower flows back upward due to the flow of inert gas.

[0119] Furthermore, in the above embodiment, when the pressure of the gas phase in the first tank 20A becomes equal to or higher than a preset reference pressure, the liquid level adjustment valve 122 is opened to send the liquid in the first tank 20A to the lower part of the second tank 30A. Therefore, the inert gas sequentially introduced into the first tank 20A prevents the pressure of the gas phase in the first tank 20A from increasing excessively. As a result, the ammonia absorbency of the absorption liquid L in the first tank 20A is prevented from decreasing.

[0120] Furthermore, in the above embodiment, when the gas-phase pressure of the first tank 20A falls below a preset lower limit pressure, the liquid level adjustment valve 122 can be opened to return the liquid in the second tank 30A to the lower part of the first tank 20A. This prevents the gas-phase pressure in the first tank 20A from becoming excessively low. Furthermore, by returning the liquid in the second tank 30A to the lower part of the first tank 20A, the liquid level of the liquid in the first tank 20A rises. This allows the gas in the gas phase of the first tank 20A to be efficiently pushed out and discharged when the liquid in the gas phase of the first tank 20A is discharged through the first gas discharge line 41.

[0121] (Other embodiments) The above describes in detail the embodiments of the present disclosure with reference to the drawings, but the specific configuration is not limited to this embodiment, and design changes and the like are also included within the scope that does not deviate from the gist of the present disclosure. The ammonia detoxification system 100A of the first embodiment is provided with a pressure adjusting unit 110, and the ammonia detoxification system 100B of the second embodiment is provided with a liquid level adjusting unit 120. However, as in the ammonia detoxification system 100C shown in Figure 24, both the pressure adjusting unit 110 and the liquid level adjusting unit 120 may be provided. In this case, the ammonia detoxification method S10 shown in Figure 3 and the ammonia detoxification method S20 shown in Figure 14 may be combined as appropriate.

[0122] Furthermore, in the first and second embodiments and their modifications, the spray 24 is provided as the first absorption promoter 22A and the spray 34 is provided as the second absorption promoter 32A, but the present invention is not limited to this. FIG. 25 is a diagram showing the configuration of an ammonia detoxification system according to another modification of the first and second embodiments of the present disclosure. As shown in FIG. 25, an ammonia abatement system 100D may include a nozzle 128 as the first absorption promoter 22B and a nozzle 138 as the second absorption promoter 32B. The nozzle 128 is immersed in the liquid phase of the first tank 20B. The nozzle 128 diffuses the purge gas introduced from the first introduction line 15 in the form of bubbles into the liquid phase of the first tank 20B. The nozzle 138 is immersed in the liquid phase of the second tank 30B. The nozzle 138 diffuses the purge gas introduced from the second inlet line 16 into the liquid phase of the second tank 30B in the form of bubbles. By diffusing the purge gas into the liquid phase from such nozzles 128, 138, ammonia contained in the purge gas is easily absorbed by the absorption liquid L contained in the liquid phase.

[0123] FIG. 26 is a diagram showing the configuration of an ammonia detoxification system according to another modification of the first and second embodiments of the present disclosure. As shown in FIG. 26, an ammonia detoxification system 100E may include an ejector 129 as a first absorption promoter 22C and an ejector 139 as a second absorption promoter 32C. The ejector 129 sucks out the gas in the gas phase in the first tank 20C, mixes it with the purge gas introduced from the first introduction line 15, and returns it to the first tank 20C. The ejector 139 sucks out the gas in the gas phase in the second tank 30C, mixes it with the purge gas introduced from the second inlet line 16, and returns it to the second tank 30C. By diffusing the purge gas from such ejectors 129, 139 into the liquid phase, ammonia contained in the purge gas is easily absorbed by the absorption liquid L contained in the liquid phase.

[0124] Furthermore, in the first and second embodiments and their respective modifications, a second liquid discharge line 52 and a third liquid discharge line 53 are provided. For example, if the liquid level adjustment valve 122 of the liquid level adjustment unit 120 fails, the second liquid discharge line 52 can transfer the liquid phase liquid in the second tank 30A to the first tank 20A by operating the circulation pump 25. Similarly, for example, if the liquid level adjustment valve 122 of the liquid level adjustment unit 120 fails, the third liquid discharge line 53 can transfer the liquid phase liquid in the first tank 20A to the second tank 30A by operating the circulation pump 35.

[0125] In the first and second embodiments and their modifications, the second tanks 30A to 30C are provided with the second absorption promoters 32A to 32C, etc., so that they can be used in place of the first tanks 20A to 20C when the first tanks 20A to 20C are unavailable for some reason. However, this is not limiting. The second tanks 30A to 30C may be configured without the second absorption promoters 32A to 32C, etc.

[0126] In the second embodiment, when the pressure of the gas phase in the first tank 20A increases, the liquid in the liquid phase in the first tank 20A is transferred to the second tank 30A, but this is not limited to this. For example, when the pressure of the gas phase in the first tank 20A increases, the liquid in the liquid phase in the first tank 20A may be drained into the first wastewater tank 60 and the second wastewater tank 70, thereby reducing the pressure of the gas phase in the first tank 20A.

[0127] Furthermore, in the above-described first and second embodiments and their respective modified examples, the configuration of the ammonia component removal section 80 has been exemplified. However, the ammonia component removal section 80 is not limited to one having the denitrification reaction section 83, and other types may be used as appropriate, as long as they can remove the ammonia components contained in the ammonia water.

[0128] In the first and second embodiments and their modifications, the water produced by the denitrification reaction in the denitrification reaction section 83 is discharged into the surrounding seawater from the discharge section 89, but this is not limiting. For example, the water produced by the denitrification reaction may be used on board the ship.

[0129] Furthermore, in the above first and second embodiments and their respective modified examples, examples have been given of the treatment of treated water stored in the second wastewater tank 70, but treatments other than those exemplified above may also be performed. For example, when fresh water is introduced into the first tank 20A and the second tank 30A, the liquid (ammonia water) stored in the second wastewater tank 70 may be put into a combustion device such as an incinerator, engine, or boiler and combusted. In addition, when fresh water is introduced into the first tank 20A and the second tank 30A, a process such as stripping may be performed in which steam or air is blown into the liquid stored in the second wastewater tank 70 to separate ammonia gas and water.

[0130] In the first and second embodiments and their modifications, when the gas in the gas phase of the first tank 20A is released into the atmosphere through the atmosphere vent line 43, the ammonia concentration of the discharged gas is reduced by the dilution fan 45. However, this is not limiting. For example, the gas in the gas phase of the first tank 20A may be subjected to ammonia concentration reduction treatment by contact with water, ammonia concentration reduction treatment using a catalytic reaction, ammonia detoxification treatment by combustion using a gas combustion unit (GCU), or the like before being released into the atmosphere.

[0131] <Additional Notes> The ammonia detoxification systems 100A to 100E, the floating body 1, and the ammonia detoxification method S10 described in each embodiment can be understood, for example, as follows.

[0132] (1) The ammonia detoxification system 100A, 100C to 100E according to the first aspect includes first tanks 20A to 20C for storing an absorption liquid L capable of absorbing ammonia, a first introduction line 15 capable of introducing a purge gas containing ammonia and an inert gas into the first tanks 20A to 20C, first absorption promotion units 22A to 22C for promoting absorption of ammonia by the absorption liquid L in the first tanks 20A to 20C, and a first absorption promotion unit 22B to 22C capable of discharging a liquid from the liquid phase of the first tanks 20A to 20C. The system is equipped with a liquid discharge line 51, a first gas discharge line 41 capable of discharging gas from the gas phase of the first tanks 20A to 20C, second tanks 30A to 30C provided independently of the first tanks 20A to 20C, an upper connection line 111 connecting the gas phase at the top of the first tanks 20A to 20C with the top of the second tanks 30A to 30C, and a pressure regulating valve 112 provided on the upper connection line 111 and capable of opening and closing according to the pressure of the gas phase of the first tanks 20A to 20C.

[0133] In the ammonia abatement systems 100A, 100C to 100E, when piping through which ammonia flows is purged with an inert gas, the inert gas is fed into the piping, and a purge gas containing ammonia and the inert gas is introduced into the first tanks 20A to 20C through the first inlet line 15. The ammonia contained in the introduced purge gas is absorbed into the absorption liquid L stored in the first tanks 20A to 20C. At this time, the first absorption promoters 22A to 22C promote the absorption of ammonia by the absorption liquid L in the first tanks 20A to 20C. The absorption liquid L that has absorbed ammonia in the first tanks 20A to 20C, i.e., the liquid phase liquid in the first tanks 20A to 20C, is discharged from the first tanks 20A to 20C through the first liquid discharge line 51. As a result of the absorption of ammonia by the absorbing liquid L in the first tanks 20A to 20C, the gas in the gas phase in the first tanks 20A to 20C, in which the ammonia concentration has been reduced, is discharged from the first tanks 20A to 20C through the first gas discharge line 41. If the inert gas contained in the purge gas is not easily absorbed by the absorbing liquid L in the first tanks 20A-20C, the inert gas remaining without being absorbed by the absorbing liquid L accumulates in the gas phase of the first tanks 20A-20C. As the purge progresses, the proportion (flow rate) of the inert gas in the purge gas introduced into the first tanks 20A-20C increases. In this way, the inert gas sequentially introduced into the first tanks 20A-20C increases the pressure of the gas phase of the first tanks 20A-20C. The first tanks 20A-20C and the second tanks 30A-30C are connected by an upper connection line 111. When the pressure adjustment valve 112 opens in response to the pressure of the gas phase of the first tanks 20A-20C, the gas in the gas phase at the top of the first tanks 20A-20C is transferred to the top of the second tanks 30A-30C. This reduces the pressure of the gas phase of the first tanks 20A-20C. Therefore, the first tanks 20A-20C can further receive the purge gas that flows in thereafter. As a result, the first tanks 20A-20C can receive the large amount of purge gas that flows in during purging, allowing more ammonia to be absorbed. Furthermore, when the inert gas is discharged from the first tanks 20A-20C through the first gas discharge line 41, the pressure of the inert gas is reduced. Therefore, even if a closed space is provided downstream of the first gas discharge line 41, a phenomenon such as flooding, in which water supplied into the closed space flows back upward due to the flow of the inert gas, can be prevented. Therefore, it is possible to ensure the ammonia absorption during purging.

[0134] (2) The ammonia detoxification systems 100A, 100C to 100E according to the second aspect are the ammonia detoxification systems 100A, 100C to 100E of (1), in which the pressure regulating valve 112 opens when the pressure of the gas phase of the first tanks 20A to 20C becomes equal to or higher than a preset reference pressure, thereby connecting the gas phase of the first tanks 20A to 20C with the upper portions of the second tanks 30A to 30C.

[0135] As a result, when the pressure of the gas phase in the first tanks 20A to 20C reaches or exceeds a preset reference pressure, the pressure regulating valve 112 opens, connecting the gas phase in the first tanks 20A to 20C with the upper portions of the second tanks 30A to 30C. Therefore, the inert gas sequentially introduced into the first tanks 20A to 20C prevents the pressure of the gas phase in the first tanks 20A to 20C from increasing excessively.

[0136] (3) The ammonia detoxification systems 100C to 100E according to the third aspect are any one of the ammonia detoxification systems 100C to 100E according to (1) or (2), and further include a lower connection line 121 that connects the liquid phase at the bottom of the first tank 20A to 20C with the bottom of the second tank 30A to 30C, and a liquid level control valve 122 that is provided in the lower connection line 121 and can be opened and closed depending on the pressure of the gas phase of the first tank 20A to 20C.

[0137] As a result, the first tanks 20A to 20C and the second tanks 30A to 30C are connected by the lower connection line 121. When the liquid level adjustment valve 122 opens in response to the pressure of the gas phase in the first tanks 20A to 20C, the liquid phase in the lower part of the first tanks 20A to 20C is transferred to the lower part of the second tanks 30A to 30C. This increases the volume of the gas phase in the first tanks 20A to 20C, and reduces the pressure of the gas phase. This allows the first tanks 20A to 20C to further receive the purge gas that flows in thereafter. As a result, the first tanks 20A to 20C can receive a large amount of purge gas that flows in during purging, allowing more ammonia to be absorbed.

[0138] (4) The ammonia detoxification systems 100C to 100E according to the fourth aspect are the ammonia detoxification systems 100C to 100E of (3), in which the liquid level control valve 122 opens when the pressure of the gas phase of the first tanks 20A to 20C reaches or exceeds a predetermined reference pressure, thereby connecting the liquid phase of the first tanks 20A to 20C with the lower part of the second tanks 30A to 30C.

[0139] As a result, when the pressure of the gas phase in the first tanks 20A to 20C reaches or exceeds a preset reference pressure, the liquid phase in the first tanks 20A to 20C is sent to the lower parts of the second tanks 30A to 30C by opening the liquid level adjustment valve 122. Therefore, the inert gas sequentially introduced into the first tanks 20A to 20C prevents the pressure of the gas phase in the first tanks 20A to 20C from increasing excessively.

[0140] (5) The ammonia detoxification systems 100C to 100E according to the fifth aspect are the ammonia detoxification systems 100C to 100E of (4), in which the liquid level control valve 122 opens when the gas phase pressure of the first tanks 20A to 20C falls below a preset lower limit pressure, and returns the liquid phase liquid of the second tanks 30A to 30C to the bottom of the first tanks 20A to 20C.

[0141] As a result, when the gas phase pressure of the first tanks 20A-20C falls below a preset lower limit pressure, the liquid level adjustment valve 122 can be opened to return the liquid phase of the second tanks 30A-30C to the lower parts of the first tanks 20A-20C. This prevents the gas phase pressure in the first tanks 20A-20C from becoming excessively low. Furthermore, by returning the liquid phase of the second tanks 30A-30C to the lower parts of the first tanks 20A-20C, the liquid level of the liquid phase in the first tanks 20A-20C rises. This allows the gas phase of the first tanks 20A-20C to be efficiently pushed out and discharged through the first gas discharge line 41.

[0142] (6) The ammonia detoxification system 100A, 100C to 100E according to a sixth aspect is any one of the ammonia detoxification systems 100A, 100C to 100E according to (1) to (5), wherein the second tanks 30A to 30C store an absorption liquid L capable of absorbing ammonia, and are provided with a second inlet line 16 capable of introducing a purge gas containing ammonia and an inert gas into the second tanks 30A to 30C, and a second absorption promoter 32A that promotes the absorption of ammonia by the absorption liquid L in the second tanks 30A to 30C.

[0143] As a result, when the purge gas containing ammonia and an inert gas is introduced into the second tanks 30A-30C through the second inlet line 16, the ammonia contained in the purge gas is absorbed by the absorbing solution L stored in the second tanks 30A-30C. At this time, the second absorption promoter 32A promotes the absorption of ammonia by the absorbing solution L in the second tanks 30A-30C. In this manner, the second tanks 30A-30C can also absorb ammonia contained in the purge bath, similar to the first tanks 20A-20C. Therefore, if for some reason the first tanks 20A-20C are no longer able to absorb ammonia, the second tanks 30A-30C can absorb ammonia instead of the first tanks 20A-20C. This increases the redundancy of the ammonia abatement systems 100A-100E.

[0144] (7) The seventh aspect of the ammonia detoxification system 100A, 100C to 100E is any one of the ammonia detoxification systems 100A, 100C to 100E of (1) to (6), and further includes a flow control valve 41V that adjusts the flow rate of the gas phase gas discharged from the first tank 20A to 20C through the first gas discharge line 41.

[0145] This reduces the flow rate of the gas in the gas phase of the first tanks 20A to 20C that is discharged through the first gas discharge line 41, thereby making it possible to reduce the ammonia concentration in the gas phase that is discharged from the first gas discharge line 41.

[0146] (8) An ammonia detoxification system 100A, 100C to 100E according to an eighth aspect is any one of the ammonia detoxification systems 100A, 100C to 100E according to (1) to (7), wherein the first absorption promoters 22A to 22C include at least one of a spray 24 that sprays the absorption liquid L into the first tanks 20A to 20C, a nozzle 128 that diffuses the purge gas into the absorption liquid L in the first tanks 20A to 20C, and an ejector 129 that sucks gas in the gas phase in the first tanks 20A to 20C into the flow of the absorption liquid L sent into the first tanks 20A to 20C.

[0147] As a result, the first absorption promoters 22A to 22C, which are equipped with at least one of the spray 24, the nozzle 128, and the ejector 129, can promote absorption of the ammonia contained in the purge gas by the absorbing liquid L in the first tanks 20A to 20C.

[0148] (9) The ammonia detoxification system 100A, 100C to 100E according to the ninth aspect is any one of the ammonia detoxification systems 100A, 100C to 100E according to (1) to (8), and further includes a first circulation line 23 that circulates the liquid phase in the first tanks 20A to 20C to the first absorption promotion sections 22A to 22C.

[0149] As a result, by circulating the liquid phase in the first tanks 20A to 20C through the first absorption promotion sections 22A to 22C via the first circulation line 23, it is possible to efficiently utilize the absorption liquid L and efficiently absorb ammonia by the absorption liquid L.

[0150] (10) The ammonia detoxification systems 100B to 100E according to the tenth aspect include first tanks 20A to 20C for storing an absorption liquid L capable of absorbing ammonia, a first introduction line 15 capable of introducing a purge gas containing ammonia and an inert gas into the first tanks 20A to 20C, first absorption promotion units 22A to 22C for promoting absorption of ammonia by the absorption liquid L in the first tanks 20A to 20C, and a first liquid discharge unit capable of discharging liquid from the liquid phase of the first tanks 20A to 20C. a liquid discharge line 51, a first gas discharge line 41 capable of discharging gas from the gas phase of the first tanks 20A to 20C, second tanks 30A to 30C provided independently of the first tanks 20A to 20C, a lower connection line 121 connecting the liquid phase at the bottom of the first tanks 20A to 20C with the bottom of the second tanks 30A to 30C, and a liquid level adjustment valve 122 provided on the lower connection line 121 and capable of opening and closing according to the pressure of the gas phase of the first tanks 20A to 20C.

[0151] In the ammonia abatement systems 100B-100E, when piping through which ammonia flows is purged with an inert gas, the inert gas is introduced into the piping, and a purge gas containing ammonia and the inert gas is introduced into the first tanks 20A-20C through the first inlet line 15. The ammonia contained in the introduced purge gas is absorbed into the absorbing liquid L stored in the first tanks 20A-20C. At this time, the first absorption promoters 22A-22C promote absorption of ammonia by the absorbing liquid L in the first tanks 20A-20C. If the inert gas contained in the purge gas is not easily absorbed by the absorbing liquid L in the first tanks 20A-20C, the inert gas that is not absorbed by the absorbing liquid L accumulates in the gas phase of the first tanks 20A-20C. As the purge progresses, the proportion (flow rate) of the inert gas in the purge gas introduced into the first tanks 20A-20C increases. In this way, the inert gas sequentially introduced into the first tanks 20A-20C increases the pressure of the gas phase in the first tanks 20A-20C. The first tanks 20A-20C and the second tanks 30A-30C are connected by a lower connection line 121. When the liquid level control valve 122 opens in response to the pressure of the gas phase in the first tanks 20A-20C, the liquid phase in the lower part of the first tanks 20A-20C is transferred to the lower part of the second tanks 30A-30C. This increases the volume of the gas phase in the first tanks 20A-20C and reduces the pressure of the gas phase. This allows the first tanks 20A-20C to further absorb the purge gas that subsequently flows in. As a result, the first tanks 20A-20C can absorb a large amount of purge gas that flows in during purging, allowing more ammonia to be absorbed. Furthermore, the pressure of the inert gas is reduced even when the inert gas is discharged from inside the first tanks 20A to 20C through the first gas discharge line 41. As a result, even when a closed space is provided downstream of the first gas discharge line 41, a phenomenon such as flooding, in which water supplied into the closed space flows back upward due to the flow of the inert gas, can be prevented. Therefore, it is possible to ensure the ammonia absorption during purging.

[0152] (11) A floating body 1 according to an eleventh aspect includes a floating body main body 2 and any one of the ammonia detoxification systems 100A to 100E according to (1) to (10).

[0153] With this configuration, it is possible to provide a floating body 1 equipped with the ammonia detoxification systems 100A to 100E that can ensure ammonia absorption during purging.

[0154] (12) An ammonia detoxification method S10 according to a twelfth aspect is an ammonia detoxification method S10 in any one of the ammonia detoxification systems 100A to 100E of (1) to (10), and includes the steps of: storing an absorption liquid L capable of absorbing ammonia in a first tank 20A to 20C in step S11; introducing a purge gas containing ammonia and an inert gas into the first tank 20A to 20C in step S12; absorbing the ammonia contained in the purge gas introduced into the first tank 20A to 20C with the absorption liquid L in step S13; and transferring the gas in the gas phase at the top of the first tank 20A to 20C to the second tank 30A to 30C in step S15 when the gas phase in the first tank 20A to 20C reaches a predetermined reference pressure or higher.

[0155] In this ammonia detoxification method S10, when purge gas is introduced into the first tanks 20A-20C, the ammonia contained in the purge gas is absorbed by the absorption liquid L stored in the first tanks 20A-20C. Due to the inert gas being sequentially introduced into the first tanks 20A-20C, the gas phase pressure in the first tanks 20A-20C increases. When this pressure exceeds the reference pressure, the gas in the gas phase at the top of the first tanks 20A-20C is transferred to the top of the second tanks 30A-30C, thereby reducing the gas phase pressure in the first tanks 20A-20C. This allows the first tanks 20A-20C to further accommodate the purge gas that subsequently flows in. As a result, the first tanks 20A-20C can accommodate a large amount of purge gas that flows in during purging, allowing more ammonia to be absorbed. Furthermore, even when the inert gas is discharged from the first tanks 20A to 20C through the first gas discharge line 41, the pressure of the inert gas is reduced, so even if a closed space is provided downstream of the first gas discharge line 41, the flow of the inert gas can be prevented from causing a phenomenon such as flooding, in which water supplied into the closed space flows back upward. Therefore, it is possible to ensure the ammonia absorption during purging. [Explanation of symbols]

[0156] 1...Floating body 2...Floating body main body 2a...Bow 4...Superstructure 5A 5B...Side 6...Bottom of the vessel 7...Upper deck 8...Combustion device 9...Funnel 10...Purge gas inlet 11...Main inlet line 12...Tank inlet line 13...Bypass line 13V...Shut-off valve 14...Main piping 14V...Shut-off valve 15...First inlet line 15V...Shut-off valve 16...Second inlet line 16V...Shut-off valve 20A-20C...First tank 21...Tank main body 22A-22C...First absorption promoter 23...First circulation line 23a...Part 23j...Part 24...Spray 25...Circulation pump 26...Heat exchanger 27...Intake pipe 28...Level gauge 29...Pressure gauge 30A-30C...Second tank 31...Tank main body 32A-32C... Second absorption promotion section 33... Second circulation line 34... Spray 35... Circulation pump 36... Heat exchanger 37... Water intake pipe 38... Level gauge 39... Pressure gauge 40... Exhaust section 41... First gas discharge line 41V... Flow rate control valve 42... Second gas discharge line 42V... Flow rate control valve 43... Atmospheric release line 44... Dilution line 45... Dilution fan 50... Drainage section 51... First liquid discharge line 52... Second liquid discharge line 52V... On-off valve 53... Third liquid discharge line 53V... On-off valve 55... Drainage line 56 57... Branch piping 56V 57V... On-off valve 60... First wastewater tank 61... Drainage line 62... Pump 68... Unloading line 70... Second wastewater tank 80... Ammonia component removal section 81... Electrolysis section 83... Denitrification reaction section 89...Discharge section 100A-100E...Ammonia abatement system 110...Pressure adjustment section 111...Upper connecting line 112...Pressure adjustment valve 120...Liquid level adjustment section 121...Lower connecting line 122...Liquid level adjustment valve 128...Nozzle 129...Ejector 138...Nozzle 139...Ejector FA...Fore-aft direction L...Absorption liquid S10 S20...Ammonia abatement method S11 S21...Storage process of absorption liquid S12 S22...Process of introducing purge gas S13 S23...Process of absorbing ammonia S14 S24...Process of checking the pressure of the gas phase S15...Process of transferring the gas phase gas S16 S26...Process of checking the completion of purging S17 S27...Process of finishing the introduction of purge S17A S27A...Process of bringing ammonia into gas-liquid equilibrium S18 S28...Process of discharging the gas phase S19 S29: Discharge of the liquid phaseS25: Transferring the liquid phase

Claims

1. a first tank for storing an absorption liquid capable of absorbing ammonia; a first introduction line capable of introducing a purge gas containing ammonia and an inert gas into the first tank; a first absorption promotion unit that promotes absorption of ammonia by the absorption liquid in the first tank; a first liquid discharge line capable of discharging liquid from the liquid phase of the first tank; a first gas discharge line capable of discharging gas from the gas phase of the first tank; a second tank provided independently of the first tank; an upper connection line connecting the gas phase at the upper part of the first tank and the upper part of the second tank; a pressure regulating valve provided in the upper connecting line and capable of opening and closing in accordance with the gas phase pressure of the first tank; An ammonia abatement system comprising:

2. The pressure regulating valve is When the pressure of the gas phase in the first tank reaches or exceeds a preset reference pressure, the valve opens, allowing the gas phase in the first tank to communicate with the upper part of the second tank.

10. The ammonia abatement system of claim 1.

3. a lower connecting line connecting the liquid phase in the lower part of the first tank with the lower part of the second tank; a liquid level adjustment valve provided in the lower connecting line and capable of opening and closing in response to the gas phase pressure of the first tank; Further provided with 3. The ammonia abatement system according to claim 1 or 2.

4. The liquid level adjustment valve is When the pressure of the gas phase in the first tank reaches or exceeds a preset reference pressure, the valve opens, allowing the liquid phase in the first tank to communicate with the lower part of the second tank. The ammonia abatement system of claim 3 .

5. The liquid level adjustment valve is When the pressure of the gas phase in the first tank falls below a preset lower limit pressure, the valve opens and returns the liquid in the liquid phase in the second tank to the bottom of the first tank. The ammonia abatement system of claim 4.

6. the second tank stores an absorption liquid capable of absorbing ammonia, a second introduction line capable of introducing a purge gas containing ammonia and an inert gas into the second tank; a second absorption promotion unit that promotes absorption of ammonia by the absorption liquid in the second tank.

3. The ammonia abatement system according to claim 1 or 2.

7. a flow rate adjusting valve for adjusting the flow rate of the gas phase gas discharged from the first tank through the first gas discharge line.

3. The ammonia abatement system according to claim 1 or 2.

8. The first absorption promoter is a sprayer for spraying the absorbing liquid into the first tank, a nozzle for diffusing the purge gas into the absorbing liquid in the first tank, and an ejector for sucking gas in the gas phase in the first tank into the flow of the absorbing liquid sent into the first tank.

3. The ammonia abatement system according to claim 1 or 2.

9. a first circulation line for circulating the liquid phase in the first tank to the first absorption promotion section; 3. The ammonia abatement system according to claim 1 or 2.

10. a first tank for storing an absorption liquid capable of absorbing ammonia; a first introduction line capable of introducing a purge gas containing ammonia and an inert gas into the first tank; a first absorption promotion unit that promotes absorption of ammonia by the absorption liquid in the first tank; a first liquid discharge line capable of discharging liquid from the liquid phase of the first tank; a first gas discharge line capable of discharging gas from the gas phase of the first tank; a second tank provided independently of the first tank; a lower connecting line connecting the liquid phase in the lower part of the first tank with the lower part of the second tank; a liquid level adjustment valve provided in the lower connecting line and capable of opening and closing in response to the gas phase pressure of the first tank; An ammonia abatement system comprising:

11. A floating body; The ammonia detoxification system according to claim 1 or 2. Floating body.

12. 3. An ammonia detoxification method in an ammonia detoxification system according to claim 1 or 2, storing an absorption liquid capable of absorbing ammonia in a first tank; introducing a purge gas containing ammonia and an inert gas into the first tank; a step of absorbing ammonia contained in the purge gas introduced into the first tank with the absorption liquid; and transferring the gas in the gas phase in the upper part of the first tank to the second tank when the gas phase in the first tank reaches a predetermined reference pressure or higher. Ammonia detoxification method.

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