Ammonia gas treatment device and treatment method

Abstract

The present invention aims to provide an ammonia gas treatment device and treatment method using a neutralizing agent that is easy to handle and safe compared to sulfuric acid, etc. The problem is solved by an ammonia gas treatment device for a ship carrying liquefied ammonia as cargo or engine fuel, which is equipped with a decontamination device (6) that receives ammonia gas and / or ammonia gas vaporized from liquefied ammonia that volatilizes from the cargo or remains in the engine's fuel supply line, and within the decontamination device (6), the ammonia gas and / or ammonia gas vaporized into liquefied ammonia is absorbed into clean water and neutralized into an organic acid, and the neutralized water is supplied to a neutralized water storage tank (15).

Description

Technology Field

[0001] The present invention relates to a method for treating ammonia gas in a vessel carrying liquefied ammonia as cargo or engine fuel, and specifically, to an ammonia gas treatment apparatus and treatment method using a neutralizing agent that is easier to handle and safer than sulfuric acid, etc. Background Technology

[0002] Recently, due to global warming concerns, the use of liquefied ammonia as fuel for ship propulsion engines is anticipated. When using liquefied ammonia as fuel, it may be necessary to vent residual gases from the fuel piping after combustion is stopped, or to empty the fuel supply system to maintain combustion within the normal range in the event of an abnormality. Additionally, ammonia gas known as boil-off gas is generated in storage tanks due to factors such as natural heat absorption. If left unchecked, this generated ammonia gas can cause the pressure inside the tank to rise and exceed the design pressure; therefore, it must be treated through methods such as atmospheric release.

[0003] However, since ammonia gas is flammable and toxic, releasing it directly into the atmosphere can affect the human body. Therefore, it is necessary to remove ammonia gas from exhaust gases released into the atmosphere using a decontamination device.

[0004] In addition, a method of re-liquefying ammonia gas and returning it to the tank is also being used. However, since re-liquefaction requires a large amount of electricity, there are issues in terms of energy efficiency.

[0005] Patent Document 1 describes a method of recovering ammonia water by absorbing ammonia gas into water using a decontamination device. It explains that the recovered ammonia water is diluted or neutralized using an acidic neutralizing agent.

[0006] It is known that strong acids, such as sulfuric acid or nitric acid, are used as acidic neutralizing agents to neutralize ammonia water.

[0007] In addition, even if ammonia water is neutralized, considering the impact on the marine environment, there are cases where it cannot be discharged overboard due to discharge regulations depending on the sea area; in such cases, the neutralized water must be stored or treated on board. Prior art literature

[0008] [Patent Literature 1] Patent Publication No. 6934555 The problem to be solved

[0009] Meanwhile, since strong acid neutralizing agents such as sulfuric acid or nitric acid are hazardous substances, extreme caution is required for their use and storage on board.

[0010] Therefore, the objective of the present invention is to provide an ammonia gas treatment apparatus and a treatment method using a neutralizing agent that is easier to handle and safer than sulfuric acid, etc.

[0011] In addition, other problems of the present invention are clarified by the following description. means of solving the problem

[0012] The above problem is solved by each of the following inventions.

[0013] 1.

[0014] As an ammonia gas treatment device for a vessel carrying liquefied ammonia as fuel for cargo or the vessel's engine,

[0015] Equipped with a decontamination device that receives vaporized ammonia gas and / or ammonia gas, liquefied ammonia that volatilizes from the above cargo or remains in the fuel supply line of the above engine,

[0016] An ammonia gas treatment device characterized in that, within the above-mentioned decontamination device, the liquefied ammonia is vaporized into ammonia gas and / or the ammonia gas is absorbed into clean water and neutralized into an organic acid, and the neutralized water is transferred to a neutralized water storage tank.

[0017] 2.

[0018] An ammonia gas treatment device described in 1, characterized by having a neutralizing solution manufacturing device that produces a neutralizing solution, which is an aqueous organic acid solution, from clean water and an organic acid, and supplies the clean water and the organic acid, which are components of the neutralizing solution, to the decontamination device.

[0019] 3.

[0020] An ammonia gas treatment device described in 1, characterized by having a neutralization solution tank that stores a neutralization solution, which is an aqueous solution of organic acid composed of clean water and an organic acid, and supplies the clean water and the organic acid, which are components of the neutralization solution, to the decontamination device.

[0021] 4.

[0022] The above-mentioned decontamination device receives the above-mentioned clean water, and

[0023] An ammonia gas treatment device described in 1, characterized by having a neutralizing agent tank that stores solid organic acids and supplies the solid organic acids to the decontamination device as organic acids.

[0024] 5.

[0025] As an ammonia gas treatment device for a vessel carrying liquefied ammonia as cargo or engine fuel,

[0026] A decontamination device that receives vaporized ammonia gas and / or ammonia gas from liquefied ammonia that volatilizes from the above cargo or remains in the fuel supply line of the above engine, absorbs this ammonia gas into fresh water to produce ammonia water, and sends this ammonia water to a neutralization treatment device, and

[0027] Equipped with a neutralizing agent tank that stores organic acids and supplies these organic acids to the neutralization treatment device,

[0028] An ammonia gas treatment device characterized by the fact that, within the above-mentioned neutralization treatment device, the ammonia water is neutralized by the organic acid and the neutralized water is transferred to a neutralized water storage tank.

[0029] 6.

[0030] The ammonia gas treatment device described in 5, characterized by having a return pipe from downstream of the neutralization treatment device to upstream of the neutralization treatment device.

[0031] 7.

[0032] As an ammonia gas treatment device for a vessel carrying liquefied ammonia as cargo or engine fuel,

[0033] A decontamination device that receives vaporized ammonia gas and / or ammonia gas from liquefied ammonia that volatilizes from the above cargo or remains in the fuel supply line of the above engine, absorbs this ammonia gas into fresh water to produce ammonia water, and transfers this ammonia water to a neutralized water storage tank, and

[0034] Equipped with a neutralizing agent tank that stores organic acids and supplies these organic acids to the neutralizing water storage tank,

[0035] An ammonia gas treatment device characterized by the ammonia water being neutralized by the organic acid within the above-mentioned neutralization water storage tank.

[0036] 8.

[0037] As an ammonia gas treatment device for a vessel carrying liquefied ammonia as cargo or engine fuel,

[0038] A decontamination device that receives vaporized ammonia gas and / or ammonia gas from liquefied ammonia that volatilizes from the above cargo or remains in the fuel supply line of the above engine, absorbs such ammonia gas into clean water to convert it into ammonia water, and then transfers such ammonia water to a neutralized water storage tank, and

[0039] Equipped with a neutralizing agent tank that stores organic acids and supplies these organic acids to a neutralization treatment device,

[0040] An ammonia gas treatment device characterized in that the ammonia water circulates between the neutralization treatment device and the neutralization water storage tank, and the circulating ammonia water is neutralized by the organic acid.

[0041] 9.

[0042] An ammonia gas treatment device described in 8, characterized in that the supply of the ammonia water from the above-described decontamination device to the above-described neutralization water storage tank is performed via the above-described neutralization treatment device.

[0043] 10.

[0044] A reducing agent supply device that generates ammonia gas from the neutralized water in which the above ammonia has been neutralized, and

[0045] An ammonia gas treatment device described in any one of 1 to 9, characterized by having a transport unit that supplies ammonia gas generated by the above-mentioned reducing agent supply device to a selective reduction catalyst unit connected to the above-mentioned device.

[0046] 11.

[0047] An ammonia gas treatment device described in 10, characterized by storing the neutralizing agent residue after ammonia gas is generated in the above-mentioned reducing agent supply device as a reusable neutralizing agent.

[0048] 12.

[0049] A method for treating ammonia gas in a vessel carrying liquefied ammonia as cargo or engine fuel,

[0050] Liquid ammonia that volatilizes from the above cargo or remains in the fuel supply line of the above engine is vaporized ammonia gas and / or ammonia gas is received in a decontamination device, and

[0051] A method for treating ammonia gas characterized by, within the above-mentioned decontamination device, absorbing the liquefied ammonia into vaporized ammonia gas and / or the ammonia gas into clean water, neutralizing it with an organic acid, and then transferring the neutralized water to a neutralized water storage tank.

[0052] 13.

[0053] Ammonia gas treatment method described in 12, characterized by preparing a neutralizing solution, which is an aqueous organic acid solution, from clean water and an organic acid using a neutralizing solution manufacturing device, and supplying the clean water and the organic acid, which are components of the neutralizing solution, to the decontamination device.

[0054] 14.

[0055] A method for treating ammonia gas as described in 12, characterized by storing a neutralizing solution, which is an aqueous solution of organic acid composed of clean water and organic acid, in a neutralizing solution tank, and supplying the clean water and organic acid, which are components of the neutralizing solution, to a decontamination device.

[0056] 15.

[0057] Supply the clean water to the above-mentioned pollution removal device, and

[0058] Ammonia gas treatment method described in 12, characterized by storing a solid organic acid in a neutralizing agent tank and supplying the solid organic acid to the decontamination device as said organic acid.

[0059] 16.

[0060] A method for treating ammonia gas in a vessel carrying liquefied ammonia as cargo or engine fuel,

[0061] Liquid ammonia that volatilizes from the above cargo or remains in the fuel supply line of the above engine is vaporized into ammonia gas and / or ammonia gas and is received in a decontamination device, the ammonia gas is absorbed into clean water to form ammonia water, and the ammonia water is transferred to a neutralization treatment device.

[0062] An organic acid is stored in a neutralizing agent tank, and this organic acid is supplied to the above-mentioned neutralization treatment device,

[0063] A method for treating ammonia gas characterized by neutralizing the ammonia water using the organic acid in the above-mentioned neutralization treatment device, and transferring the neutralized water to a neutralized water storage tank.

[0064] 17.

[0065] The ammonia gas treatment method described in 16, characterized by installing a return pipe from downstream of the neutralization treatment device to upstream of the neutralization treatment device.

[0066] 18.

[0067] A method for treating ammonia gas in a vessel carrying liquefied ammonia as cargo or engine fuel,

[0068] Liquid ammonia that volatilizes from the above cargo or remains in the fuel supply line of the above engine is vaporized into ammonia gas and / or ammonia gas, which is then received in a decontamination device, and this ammonia gas is absorbed into fresh water to form ammonia water, and this ammonia water is transferred to a neutralized water storage tank.

[0069] An organic acid is stored in a neutralizing agent tank, and this organic acid is supplied to the neutralized water storage tank.

[0070] A method for treating ammonia gas characterized by neutralizing the ammonia water with the organic acid in the above neutralization water storage tank.

[0071] 19.

[0072] A method for treating ammonia gas in a vessel carrying liquefied ammonia as cargo or engine fuel,

[0073] Liquid ammonia that volatilizes from the above cargo or remains in the fuel supply line of the above engine is vaporized into ammonia gas and / or ammonia gas, which is then received in a decontamination device, and the ammonia gas is absorbed into fresh water to be converted into ammonia water, after which the ammonia water is transferred to a neutralized water storage tank.

[0074] Organic acids are stored in a neutralizing agent tank, and these organic acids are supplied to a neutralization treatment device,

[0075] A method for treating ammonia gas characterized by circulating the ammonia water between the neutralization treatment device and the neutralization water storage tank, and neutralizing the circulating ammonia water with the organic acid.

[0076] 20.

[0077] Ammonia gas treatment method described in 19, characterized by performing the ammonia water supplied from the above-described decontamination device to the above-described neutralization water storage tank via the above-described neutralization treatment device.

[0078] 21.

[0079] Ammonia gas is generated from the neutralized water in which the above ammonia is neutralized by a reducing agent supply device, and

[0080] An ammonia gas treatment method described in any one of 12 to 20, characterized by supplying the ammonia gas generated by the above-mentioned reducing agent supply device to a selective reduction catalyst unit connected to the above-mentioned device.

[0081] 22.

[0082] A method for treating ammonia gas described in 21, characterized by storing the neutralizing agent residue after ammonia gas is generated in the above-described reducing agent supply device and reusing it as a neutralizing agent. Effects of the invention

[0083] According to the present invention, an ammonia gas treatment apparatus and treatment method using a neutralizing agent that is easier to handle and safer than sulfuric acid, etc. can be provided. Brief explanation of the drawing

[0084] FIG. 1 is a block diagram showing the configuration of an ammonia gas treatment device of a first embodiment of the present invention. Figure 2 is a graph confirming the ammonia reduction rate in the reducing agent supply device. FIG. 3 is a block diagram showing the configuration of an ammonia gas treatment device of an improved form (1) of the first embodiment of the present invention. FIG. 4 is a block diagram showing the configuration of an ammonia gas treatment device of an improved form (2) of the first embodiment of the present invention. FIG. 5 is a block diagram showing the configuration of an ammonia gas treatment device of a second embodiment of the present invention. FIG. 6 is a block diagram showing the configuration of an ammonia gas treatment device of an improved form of the second embodiment of the present invention. FIG. 7 is a block diagram showing the configuration of an ammonia gas treatment device of a third embodiment of the present invention. FIG. 8 is a block diagram showing the configuration of an ammonia gas treatment device of the fourth embodiment of the present invention. FIG. 9 is a block diagram showing the configuration of an ammonia gas treatment device of an improved form of the fourth embodiment of the present invention. Specific details for implementing the invention

[0085] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Various features shown in each of the embodiments described below may be combined with one another.

[0086] The present invention relates to an ammonia gas treatment device for a ship carrying liquefied ammonia as cargo or engine fuel, and an ammonia gas treatment method performed in such an ammonia gas treatment device.

[0087] The present invention aims to neutralize ammonia water using a neutralizing agent that is easier to handle and safer than strong acids such as sulfuric acid. In the present invention, an organic acid, such as citric acid (C6H8O7·H2O), may be used as a neutralizing agent that is easier to handle and safer than sulfuric acid.

[0088] In each of the following embodiments, citric acid is used as the organic acid, but is not limited thereto, and organic acids such as formic acid, acetic acid, malic acid, oxalic acid, lactic acid, succinic acid, tartaric acid, butyric acid, fumaric acid, and propionic acid may be used.

[0089] Hereinafter, embodiments of the present invention are classified according to the location where the neutralization process of ammonia water takes place and described with reference to the drawings.

[0090] In the first embodiment, neutralization is performed in a decontamination device (6) as shown in FIGS. 1, FIGS. 3, and FIGS. 4.

[0091] In the second embodiment, as shown in FIGS. 5 and 6, neutralization is performed in a neutralization treatment device (23).

[0092] In the third embodiment, as shown in FIG. 7, neutralization is performed in a neutralization water storage tank (15).

[0093] In the fourth embodiment, as shown in FIGS. 8 and 9, neutralization is performed during the circulation process between the neutralization water storage tank (15) and the neutralization treatment device (23).

[0094] [First embodiment]

[0095] FIG. 1 is a block diagram showing the configuration of an ammonia gas treatment apparatus according to a first embodiment of the present invention. The ammonia gas treatment method according to the first embodiment of the present invention is carried out by such an ammonia gas treatment apparatus. In FIG. 1, the flow path of the liquid is indicated by a solid line, and the flow path of the gas is indicated by a dotted line. The same applies to other drawings described later.

[0096] The ammonia gas treatment device of the present embodiment processes ammonia gas and / or ammonia gas (residual gas) in which liquefied ammonia introduced from a fuel supply line that supplies liquefied ammonia fuel from a liquefied ammonia tank (1) to an engine (3) of a ship, as shown in FIG. 1, or ammonia gas (boil-off gas) supplied from a cargo ammonia tank not shown in the drawing.

[0097] The fuel supply line consists of a fuel supply device (2) and a fuel pipe (4), and is a path that supplies liquefied ammonia fuel to the engine (3) through the fuel pipe (4) via a compressor, pump, heat exchanger, etc. included in the fuel supply device (2). For reference, the fuel supply device (2) may not be installed if unnecessary. Additionally, the fuel pipe (4) may be composed of a supply pipe that supplies ammonia gas from the fuel supply device (2) to the engine (3) and a return pipe that returns excess ammonia gas from the engine (3) to the fuel supply device (2). Although not shown in the drawing, an opening and closing valve capable of blocking the section between the liquefied ammonia tank (1) side of the fuel supply device (2) and the engine (3) side of the fuel pipe (4) may be installed on the liquefied ammonia tank (1) side of the fuel supply device (2) and the engine (3) side of the fuel pipe (4).

[0098] A liquid ammonia tank (1) stores ammonia, which is part of the fuel used in engines (3), etc. Ammonia is stored in the liquid ammonia tank (1). To maintain the liquid state of the liquid ammonia, the liquid ammonia tank (1) maintains the internal pressure at high pressure or low temperature. When a large amount of liquid ammonia is loaded onto a ship due to long voyages, a full-pressure type (atmospheric pressure type) or semi-pressure type (semi-pressurized type), which is thin and easy to process, is mainly used as the liquid ammonia tank (1). There is a suction pump inside the liquid ammonia tank (1), and through this suction pump, the stored liquid ammonia is transferred to a piping system for the fuel supply device (2).

[0099] Cargo ammonia tanks store liquid ammonia as cargo rather than as fuel used in engines (3), etc. Similar to liquid ammonia tanks (1), the internal pressure of the cargo ammonia tank is maintained at high pressure or low temperature to maintain the liquid state of the liquid ammonia inside the cargo ammonia tank. When loading a large amount of liquid ammonia onto a ship, a full-pressure type (atmospheric pressure type) or semi-pressure type (semi-pressurized type), which is thin and easy to process, is mainly used as the cargo ammonia tank.

[0100] Liquid ammonia fuel is supplied to the engine (3) from the liquid ammonia tank (1) through the fuel supply device (2). Additionally, pilot fuel may be supplied to the engine (3) from the heavy oil tank (12) through the heavy oil fuel supply device (13). There is a suction pump inside the heavy oil tank (12), and the stored pilot fuel is sent through the piping leading to the heavy oil fuel supply device (13) via this suction pump.

[0101] Pilot fuel is intended to be burned together with ammonia fuel at the start of combustion to raise the temperature inside the combustion chamber and facilitate the combustion of ammonia fuel. The supply of pilot fuel can be stopped once the temperature inside the combustion chamber has risen enough to allow combustion with only ammonia fuel. Additionally, if the engine (3) can burn with only ammonia fuel from the start, pilot fuel is not required.

[0102] Nitrogen gas is supplied to the fuel pipe (4) from the nitrogen gas supply device (11) through the opening / closing valve (10). This nitrogen gas is also supplied to the fuel supply device (2) through the fuel pipe (4). This nitrogen gas is intended to purge the liquefied ammonia remaining in the fuel pipe (4) and the fuel supply device (2) into vaporized ammonia gas and / or ammonia gas during the starting, stopping, and emergency stopping of the engine (3).

[0103] In the fuel piping (4), when the engine (3) starts, stops, or stops in an emergency, the remaining liquefied ammonia vaporized ammonia gas and / or ammonia gas is introduced into the decontamination device (6) through the gas-liquid separator (4a) and the opening / closing valve (5). Additionally, in the fuel supply device (2), when the engine (3) starts, stops, stops in an emergency, or stops in an emergency, or during maintenance, the remaining liquefied ammonia vaporized ammonia gas and / or ammonia gas is introduced into the decontamination device (6) through the opening / closing valve (2a). For reference, within the fuel supply device (2), a gas-liquid separator is installed at the outlet of the remaining liquefied ammonia vaporized ammonia gas and / or ammonia gas, along with a pump, etc.

[0104] Additionally, the gas introduced from the fuel pipe (4) and the fuel supply device (2) to the decontamination device (6) is a mixed gas of ammonia gas and purge gas (e.g., nitrogen, etc.). In this embodiment, treatment is performed on the ammonia component in the mixed gas.

[0105] When ammonia gas is introduced into the decontamination device (6), the section between the liquefied ammonia tank (1) side of the fuel supply device (2) and the engine (3) side of the fuel piping (4) is blocked by an opening / closing valve. Additionally, ammonia gas (boil-off gas) is introduced into the decontamination device (6) from the cargo ammonia tank. For reference, the nitrogen gas for purging is discharged into the atmosphere through the decontamination device (6).

[0106] In the decontamination device (6), ammonia gas is absorbed into clean water and simultaneously neutralized by an organic acid. In this embodiment, a neutralizing solution (e.g., an aqueous citric acid solution) is supplied to the decontamination device (6) via a pump from a neutralizing solution manufacturing device (14) which is an aqueous organic acid solution, and clean water and a neutralizing agent (organic acid) are supplied as components of this neutralizing solution.

[0107] The neutralizing agent, which is a component of the neutralizing solution, is citric acid, a solid (powdered) organic acid, in this embodiment. The solid (powdered) citric acid is manufactured on land. For reference, citric acid is a colorless or white solid at room temperature. The neutralizing agent is supplied to the neutralizing solution manufacturing device (14).

[0108] The clean water, which is a component of the neutralizing liquid, is, for example, generated by a water purifier on board and supplied to the neutralizing liquid manufacturing device (14), but the clean water stored in advance may also be supplied to the neutralizing liquid manufacturing device (14).

[0109] The neutralization liquid manufacturing device (14) receives clean water and a neutralizing agent (citric acid powder) to produce a liquid neutralization liquid (aqueous citric acid solution) and then transfers it to the decontamination device (6) via a pump. In the decontamination device (6), residual liquid ammonia introduced from the supply line is neutralized by being absorbed into the neutralization liquid supplied from the neutralization liquid manufacturing device (14) and / or the ammonia gas that has been vaporized.

[0110] To use a liquid neutralizing solution in the decontamination device (6), a certain amount of neutralizing solution is added to the piping, such as a stirring tank or a static mixer, for example, and neutralization is performed while checking the pH value within the decontamination device (6). Whether neutralization is performed can be checked using a pH meter installed in the decontamination device (6).

[0111] The neutralized water (ammonium citrate brine solution (HOC(COOH)(CH2COONH4)2)) that has absorbed and neutralized ammonia gas is transferred to and stored in a neutralized water storage tank (15). The transfer of liquid from the decontamination device (6) to the neutralized water storage tank (15) may be carried out by any method including overflow, gravity transfer, or pump transfer.

[0112] Stored neutralized water may be discharged overboard in areas without discharge regulations.

[0113] In this embodiment, since organic acids such as citric acid are used as neutralizing agents in the ammonia gas treatment device and ammonia gas treatment method on a ship, handling is easier and safer compared to cases where sulfuric acid, etc. are used.

[0114] The neutralized water stored in the neutralized water storage tank (15) is transferred to the reducing agent supply device (19) via the transport pump (18a), and in this reducing agent supply device (19), it is heated in the range of 100°C to 150°C to generate ammonia gas, which can be used as a reducing agent in the selective catalytic reduction (SCR) unit (17). Heating of the neutralized water can be done with a heater, or by using the arrangement of the engine (3).

[0115] Figure 2 is a graph confirming the ammonia reduction rate in the reducing agent supply device.

[0116] To confirm that ammonia gas is generated in the reducing agent supply device (19), the inventor heated the neutralized water in which 5% ammonia was absorbed into a 10% citric acid aqueous solution and confirmed the reduction rate of the ammonia aqueous solution as shown in FIG. 2.

[0117] It was confirmed that the ammonia aqueous solution content decreases with heating, with approximately 90% decreasing at 100°C or higher and more than 90% decreasing around 150°C. Through this, it was confirmed that the rate of decrease of the ammonia aqueous solution content decreases at 100°C or higher, especially at 150°C or higher, and that the citric acid content remains.

[0118] Therefore, it was confirmed that the neutralizing solution can generate ammonia gas that can be used as a reducing agent by heating it to over 100°C, especially to around 150°C or higher.

[0119] The ammonia gas generated from the reducing agent supply device (19) is supplied to the selective reduction catalyst unit (17) connected to the engine (3) by the ventilation fan (20) via the transport unit (18). For reference, the ventilation fan (20) may be installed separately. In the selective reduction catalyst unit (17), the ammonia gas reacts with NOx in the exhaust gas of the pilot fuel to perform denitrification treatment by the Selective Catalytic Reduction (SCR) method. The denitrified exhaust gas is discharged into the atmosphere. The same applies to other embodiments described later.

[0120] In this way, ammonia gas is generated from the neutralized water and utilized in the selective reduction catalyst unit (17), thereby reducing the volume of the neutralized water. Additionally, the task of unloading the neutralized water onto land becomes unnecessary, and there is no need to discharge it into the sea.

[0121] In the reducing agent supply device (19), after ammonia gas is generated, neutralizing agent residue (organic acid component) is discharged. This neutralizing agent residue can be recovered and stored, then dissolved in water and reused as a neutralizing agent. Additionally, the neutralizing agent residue may be incinerated or released into the atmosphere.

[0122] In this embodiment, since an organic acid is used as the neutralizing agent, the neutralizing agent residue discharged from the reducing agent supply device (19) is carbon, and additional treatment facilities are not required when recovering the neutralizing agent residue.

[0123] When sulfuric acid, an inorganic acid, is used as a neutralizing agent, there is a risk of dust explosions as sulfur becomes a precipitate. Additionally, sulfides are generated within the catalyst, raising concerns about clogging. Furthermore, when nitric acid, an inorganic acid, is used as a neutralizing agent, harmful gases such as NO2 are generated after neutralization, requiring the addition of appropriate treatment equipment.

[0124] [Improved form of the first embodiment (1)]

[0125] FIG. 3 is a block diagram showing the configuration of an ammonia gas treatment device of an improved form (1) of the first embodiment of the present invention.

[0126] The ammonia gas treatment device of the improved form (1) of this invention, as shown in FIG. 3, has a neutralization liquid tank (9) installed instead of the neutralization liquid manufacturing device (14) of the first embodiment.

[0127] The neutralizing solution tank (9) stores a neutralizing solution (aqueous citric acid solution) manufactured on land and supplies the neutralizing solution to the decontamination device (6) through a pump. In the decontamination device (6), ammonia gas is absorbed by clean water, which is a component of the neutralizing solution supplied from the neutralizing solution tank (9), and is neutralized by organic acid, which is a component of the neutralizing solution.

[0128] [Improved form of the first embodiment (2)]

[0129] FIG. 4 is a block diagram showing the configuration of an ammonia gas treatment device of an improved form (2) of the first embodiment of the present invention.

[0130] The ammonia gas treatment device of the present improved form (2) is configured to supply a neutralizing agent and clean water to a decontamination device (6) rather than to the neutralizing liquid manufacturing device (14) of the first embodiment, as shown in FIG. 4. In the present improved form (2), the neutralizing agent is citric acid, which is a solid (powdered) organic acid.

[0131] In this improved form (2), the fresh water, which is a component of the neutralizing liquid, can be generated, for example, by an onboard desalination unit and stored in a fresh water tank (22), or the fresh water can be stored in the tank in advance. From the fresh water tank (22), the stored fresh water is supplied to the decontamination device (6) through a supply water pump (22a). In the decontamination device (6), ammonia gas is absorbed and recovered by the fresh water supplied from the fresh water tank (22) to generate ammonia water. In the decontamination device (6), the pH of the generated ammonia water can be checked using a pH meter.

[0132] After ammonia water is generated in the decontamination device (6), a neutralizing agent is supplied to the decontamination device (6). In the decontamination device (6), the ammonia water is neutralized by the neutralizing agent. When using a neutralizing agent in solid form, a set amount of neutralizing agent is added to the stirring tank through a solid supply device, and neutralization is performed while checking the pH value inside the decontamination device (6). Whether neutralization has occurred (pH 8 or lower) can be checked using a pH meter installed in the decontamination device (6).

[0133] For reference, when using a solid neutralizing agent, the amount (volume) of the neutralized water is reduced compared to when using a liquid neutralizing agent, so the capacity of the neutralized water storage tank (15) can be reduced. In this case, it is desirable to install a heat exchanger to suppress the reaction heat within the decontamination device (6) and to lower the liquid temperature.

[0134] [Second embodiment]

[0135] FIG. 5 is a block diagram showing the configuration of an ammonia gas treatment device according to a second embodiment of the present invention. The ammonia gas treatment method according to the second embodiment of the present invention is carried out by such an ammonia gas treatment device. Symbols identical to those in FIG. 1, 3, and 4 represent identical configurations, and unless otherwise specifically stated, the descriptions in FIG. 1, 3, and 4 are adopted and omitted here.

[0136] The ammonia gas treatment device of the present embodiment is configured such that, as shown in FIG. 5, clean water supplied from a clean water tank (22) is supplied to a decontamination device (6) through a water supply pump (22a) in the same manner as the improved form (2) of the first embodiment, but unlike the improved form (2) of the first embodiment, a neutralizing agent or neutralizing liquid is stored in a neutralizing agent tank (21), and the neutralizing agent or neutralizing liquid is supplied from the neutralizing agent tank (21) to a neutralization treatment device (23).

[0137] The neutralizing agent tank (21) stores a neutralizing agent (citric acid) in solid (powder) form manufactured on land or a liquid neutralizing agent (aqueous citric acid solution) manufactured on land. When storing a solid neutralizing agent, the neutralizing agent is supplied from the neutralizing agent tank (21) by a conveying device such as a screw conveyor not shown in the drawing. In addition, when storing a liquid neutralizing agent, the neutralizing agent tank (21) discharges the neutralizing agent by a pump not shown in the drawing. The same applies to the neutralizing agent tank (21) in subsequent embodiments and improved forms.

[0138] In the decontamination device (6), ammonia gas is absorbed and recovered by the clean water supplied from the clean water tank (22) to produce ammonia water. In the decontamination device (6), the pH of the produced ammonia water can be checked using a pH meter. This ammonia water is supplied to the neutralization treatment device (23). The transfer of liquid from the decontamination device (6) to the neutralization treatment device (23) may be carried out by any method, such as overflow, gravity transfer, or pump transfer.

[0139] In the neutralization treatment device (23), the ammonia water is neutralized by a neutralizing agent or neutralizing liquid supplied from the neutralizing agent tank (21). The neutralized state (pH 8 or lower) can be confirmed by a pH meter installed in the neutralization treatment device (23).

[0140] The neutralized water, which is neutralized by an ammonia water neutralizing agent or neutralizing liquid, is temporarily stored in a neutralized water storage tank (15) so that the ammonia gas does not volatilize. The neutralized water stored in the neutralized water storage tank (15) can be discharged overboard in a sea area without discharge regulations, as in the first embodiment, or it can be sent to a reducing agent supply device (19) via a transport pump (18a) to generate ammonia gas and used as a reducing agent in a selective reduction catalyst unit (17).

[0141] When using a solid neutralizing agent, a predetermined amount of the neutralizing agent is added to the stirring tank through a solid supply device as described above, and neutralization is performed while checking the pH value inside the neutralization treatment device (23). When using a solid neutralizing agent, the amount (volume) of the neutralized water is reduced compared to when using a liquid neutralizing agent, so the capacity of the neutralized water storage tank (15) can be reduced. In this case, it is desirable to install a heat exchanger inside the neutralization treatment device (23) to suppress the reaction heat and lower the liquid temperature.

[0142] Additionally, the neutralization water storage tank (15) may be equipped with a return pipe that discharges a portion of the liquid contained in the neutralization water storage tank (15) from the neutralization water storage tank (15) through a circulation pump and returns the liquid to the neutralization treatment device (23). If the liquid containing ammonia components is sent to the neutralization water storage tank (15) through this return pipe because neutralization is not sufficient, the liquid can be returned to the neutralization treatment device (23) to perform additional neutralization. Furthermore, if the pH value of the liquid transferred to the neutralization water storage tank (15) through the return pipe becomes lower than 7 (acidic), the liquid can be returned to the neutralization treatment device (23) and mixed with a liquid having a high pH value (basic) before neutralization to perform neutralization.

[0143] In this embodiment as well, since organic acids such as citric acid are used as neutralizing agents in the ammonia gas treatment device and ammonia gas treatment method on a ship, handling is easier and safer compared to cases where sulfuric acid, etc. are used.

[0144] In this embodiment as well, since an organic acid is used as a neutralizing agent, when a reducing agent supply device (19) and a selective reduction catalyst unit (17) are installed, the neutralizing agent residue discharged from the reducing agent supply device (19) is carbon, so additional treatment facilities are not required when recovering the neutralizing agent residue.

[0145] [Improved form of the second embodiment]

[0146] FIG. 6 is a block diagram showing the configuration of an ammonia gas treatment device of an improved form of the second embodiment of the present invention.

[0147] The present improved form is, as shown in FIG. 6, in which a return pipe (23a) is installed from downstream of the neutralization treatment device (23) to upstream of the neutralization treatment device (23) in the second embodiment. The return pipe (23a) discharges a portion of the liquid contained in the neutralization treatment device (23) from the neutralization treatment device (23) through a circulation pump (23b) and introduces this liquid back into the neutralization treatment device (23).

[0148] In this improved form, if a liquid containing ammonia components remains inside the neutralization treatment device (23) because neutralization is not sufficiently performed through the return pipe (23a), this liquid can be introduced back into the neutralization treatment device (23) to perform additional neutralization. Additionally, if the pH value of the liquid supplied to the neutralization water storage tank (15) through the return pipe (23a) becomes lower than 7 (acidic), this liquid can be returned to the neutralization treatment device (23) and mixed with a liquid having a high pH value (basic) before neutralization to perform neutralization.

[0149] [Third Embodiment]

[0150] FIG. 7 is a block diagram showing the configuration of an ammonia gas treatment apparatus according to a third embodiment of the present invention. The ammonia gas treatment method according to the third embodiment of the present invention is carried out by such an ammonia gas treatment apparatus. Symbols identical to those in FIG. 1, FIG. 3 to FIG. 6 represent identical configurations, and unless otherwise specifically stated, the descriptions in FIG. 1, FIG. 3 to FIG. 6 are adopted and omitted here.

[0151] The ammonia gas treatment device of the present embodiment supplies clean water from the clean water tank (22) to the decontamination device (6) through the water supply pump (22a) in the same way as in the second embodiment as shown in FIG. 7, but unlike the first and second embodiments, it supplies a neutralizing agent or neutralizing liquid from the neutralizing agent tank (21) to the neutralized water storage tank (15).

[0152] In the decontamination device (6), ammonia gas is absorbed and recovered by the clean water supplied from the clean water tank (22) to produce ammonia water. In the decontamination device (6), the pH of the produced ammonia water can be checked using a pH meter. This ammonia water is supplied to and stored in the neutralized water storage tank (15) so that the ammonia gas does not volatilize. The transfer of liquid from the decontamination device (6) to the neutralized water storage tank (15) may be carried out by any method, such as overflow, gravity transfer, or pump transfer.

[0153] In the neutralization water storage tank (15), the ammonia water is neutralized with a neutralizing agent or neutralizing liquid supplied from the neutralizing agent tank (21). Storage in the neutralization water storage tank (15) continues until the ammonia water component is sufficiently neutralized. Whether it has been neutralized (pH 8 or lower) can be checked using a pH meter installed in the neutralization water storage tank (15).

[0154] The neutralized water stored in the neutralized water storage tank (15) can be discharged overboard in a sea area without discharge regulations, as in the first embodiment, or it can be transported to a reducing agent supply device (19) via a transport pump (18a) to generate ammonia gas and used as a reducing agent in a selective reduction catalyst unit (17).

[0155] In this embodiment as well, by using a solid neutralizing agent, the amount (volume) of the neutralized water can be reduced compared to when a liquid neutralizing agent is used, and the capacity of the neutralized water storage tank (15) can be reduced. In this case, it is preferable to install a heat exchanger inside the neutralized water storage tank (15) to suppress the reaction heat and lower the liquid temperature.

[0156] In this embodiment as well, since organic acids such as citric acid are used as neutralizing agents in the ammonia gas treatment device and ammonia gas treatment method on a ship, handling is easier and safer compared to cases where sulfuric acid, etc. are used.

[0157] In this embodiment as well, since an organic acid is used as a neutralizing agent, when a reducing agent supply device (19) and a selective reduction catalyst unit (17) are installed, the neutralizing agent residue discharged from the reducing agent supply device (19) is carbon, and additional treatment facilities are not required when recovering the neutralizing agent residue.

[0158] [Fourth embodiment]

[0159] FIG. 8 is a block diagram showing the configuration of an ammonia gas treatment apparatus according to the fourth embodiment of the present invention. The ammonia gas treatment method according to the fourth embodiment of the present invention is carried out by such an ammonia gas treatment apparatus. Symbols identical to those in FIG. 1, FIG. 3 to FIG. 7 represent identical configurations, and unless otherwise specifically stated, the descriptions in FIG. 1, FIG. 3 to FIG. 7 are adopted and omitted here.

[0160] The ammonia gas treatment device of the present embodiment is configured to circulate neutralized water stored in a neutralized water storage tank (15) between the neutralized water treatment device (23) and the neutralized water storage tank (15), as shown in FIG. 8.

[0161] In this embodiment as well, the fresh water stored in the fresh water tank (22) is supplied to the decontamination device (6) by the water supply pump (22a). In the decontamination device (6), ammonia gas is absorbed and recovered by the fresh water supplied from the fresh water tank (22) to produce ammonia water. In the decontamination device (6), the pH of the produced ammonia water can be checked using a pH meter. This ammonia water is supplied to the neutralization water storage tank (15), and a portion of it is supplied from the neutralization water storage tank (15) to the neutralization treatment device (23) via the circulation pump (23b). The transfer of liquid from the decontamination device (6) to the neutralization water storage tank (15) may be carried out by any method, such as overflow, gravity transfer, or pump transfer.

[0162] A neutralizing agent or neutralizing liquid stored in a neutralizing agent tank (21) is supplied to the neutralizing treatment device (23). In the neutralizing treatment device (23), the ammonia water is neutralized by the neutralizing agent or neutralizing liquid supplied from the neutralizing agent tank (21). Whether it has been neutralized (pH 8 or lower) can be checked by a pH meter installed in the neutralizing treatment device (23). The neutralized water, in which the ammonia water has been neutralized by the neutralizing agent or neutralizing liquid, is returned to the neutralized water storage tank (15) and stored so that the ammonia gas does not volatilize. That is, the ammonia water and the neutralized water circulate between the neutralized water storage tank (15) and the neutralizing treatment device (23).

[0163] The circulation of ammonia water and neutralized water between the neutralized water storage tank (15) and the neutralization treatment device (23) is performed until the ammonia water component is sufficiently neutralized. The neutralized water stored in the neutralized water storage tank (15) can be discharged overboard in a sea area without discharge regulations, as in the first embodiment, or sent to a reducing agent supply device (19) via a transport pump (18a) to generate ammonia gas and used as a reducing agent in a selective reduction catalyst unit (17).

[0164] In this embodiment, a portion of the ammonia water is extracted from the neutralization water storage tank (15) and supplied to the neutralization treatment device (23), so there is an advantage in that the capacity of the neutralization treatment device 23 can be reduced compared to the case where the entire amount of ammonia water discharged from the contaminant removal device (6) of the second embodiment is neutralized in a batch.

[0165] In this embodiment as well, by using a solid neutralizing agent, the amount (volume) of the neutralized water can be reduced compared to when a liquid neutralizing agent is used, and the capacity of the neutralized water storage tank (15) can be reduced. In this case, it is preferable to install a heat exchanger in the neutralization treatment device (23) to suppress the reaction heat and lower the liquid temperature.

[0166] In this embodiment as well, since organic acids such as citric acid are used as neutralizing agents in the ammonia gas treatment device and ammonia gas treatment method on a ship, handling is easier and safer compared to cases where sulfuric acid, etc. are used.

[0167] In this embodiment as well, since an organic acid is used as a neutralizing agent, when a reducing agent supply device (19) and a selective reduction catalyst unit (17) are installed, the neutralizing agent residue discharged from the reducing agent supply device (19) is carbon, and additional treatment facilities are not required when recovering the neutralizing agent residue.

[0168] [Improved form of the 4th embodiment]

[0169] FIG. 9 is a block diagram showing the configuration of an ammonia gas treatment device of an improved form of the fourth embodiment of the present invention.

[0170] As shown in FIG. 9, the improved form of the ammonia gas treatment device is configured such that the supply of ammonia water from the decontamination device (6) to the neutralization water storage tank (15) in the fourth embodiment (Fig. 8) is carried out via the neutralization treatment device (23). Otherwise, it is identical to the fourth embodiment (Fig. 8).

[0171] In this embodiment, in the neutralization treatment device (23), neutralization is started by supplying a neutralizing agent or neutralizing liquid from the neutralizing agent tank (21) to the ammonia water supplied from the contaminant removal device (6), and the ammonia water and neutralized water are supplied to the neutralized water storage tank (15). The transfer of liquid from the neutralization treatment device (23) to the neutralized water storage tank (15) may be by overflow, by gravity, or by pumping.

[0172] In this embodiment, neutralization starts faster than in the fourth embodiment, so the risk of ammonia gas volatilization from the ammonia water is further suppressed.

[0173] In the neutralization water storage tank (15), as in the fourth embodiment, a portion of the contained liquid is supplied back to the neutralization treatment device (23) by the circulation pump (23b). That is, the ammonia water and neutralization water circulate between the neutralization water storage tank (15) and the neutralization treatment device (23). The circulation of the ammonia water and neutralization water between the neutralization water storage tank (15) and the neutralization treatment device (23) is performed until the ammonia water component is sufficiently neutralized. Explanation of the symbols

[0174] 1: Liquid ammonia tank 2: Fuel supply system 2a: Opening and closing valve 3: Engine 4: Fuel piping 4a: Gas-liquid separator 5: Opening and closing valve 6: Decontamination device 9: Neutralizing solution (aqueous citric acid solution) tank 10: Opening and closing valve 11: Nitrogen gas supply device 12: Heavy oil tank 13: Heavy oil fuel supply unit 14: Apparatus for manufacturing neutralizing solution (aqueous citric acid solution) 15: Neutralized water storage tank 17: Selective Catalytic Reduction (SCR) Unit 18: Transportation Department 18a: Transport pump 19: Reducing agent supply device 20: Ventilation fan 21: Neutralizer tank 22: Freshwater tank 22a: Water supply pump 23: Neutralization treatment unit 23a: Return piping 23b: Circulation pump

Claims

Claim 1 An ammonia gas treatment device for a ship carrying liquefied ammonia as cargo or engine fuel, comprising: a decontamination device that receives one or more of ammonia gas volatilized from said cargo, ammonia gas vaporized from liquefied ammonia remaining in the engine's fuel supply line, and residual ammonia gas; and a neutralization liquid manufacturing device that produces a neutralization liquid, which is an aqueous organic acid solution, from said clean water and an organic acid, wherein said neutralization liquid is supplied to said decontamination device, and within said decontamination device, the ammonia gas received by said decontamination device is neutralized as it is absorbed into said neutralization liquid, and the neutralized neutralized water is transferred to a neutralized water storage tank. Claim 2 An ammonia gas treatment device for a ship carrying liquefied ammonia as cargo or engine fuel, comprising: a decontamination device that receives one or more of ammonia gas volatilized from said cargo, ammonia gas vaporized from liquefied ammonia remaining in the engine's fuel supply line, and residual ammonia gas; and a neutralization liquid tank that stores a neutralization liquid, which is an aqueous solution of an organic acid composed of fresh water and an organic acid, wherein said neutralization liquid is supplied to said decontamination device, and within said decontamination device, the ammonia gas received by said decontamination device is neutralized as it is absorbed into said neutralization liquid, and the neutralized neutralized water is transferred to a neutralized water storage tank. Claim 3 An ammonia gas treatment device for a ship carrying liquefied ammonia as cargo or engine fuel, comprising a decontamination device that receives one or more of ammonia gas volatilized from said cargo, ammonia gas vaporized from liquefied ammonia remaining in the engine's fuel supply line, and residual ammonia gas, wherein within said decontamination device, the ammonia gas received by said decontamination device is absorbed by said water and neutralized into an organic acid, and the neutralized water is transferred to a neutralized water storage tank, and said decontamination device receives said water, stores a solid organic acid, and has a neutralizing agent tank that supplies said solid organic acid to said decontamination device as said organic acid. Claim 4 An ammonia gas treatment device for a ship carrying liquefied ammonia as cargo or engine fuel, comprising: a decontamination device that receives one or more of ammonia gas volatilized from said cargo, ammonia gas vaporized from liquefied ammonia remaining in the engine fuel supply line, and residual ammonia gas, absorbs said ammonia gas into fresh water to form ammonia water, and transfers said ammonia water to a neutralization treatment device; and a neutralizing agent tank that stores an organic acid and supplies said organic acid to said neutralization treatment device, wherein within said neutralization treatment device, said ammonia water is neutralized by said organic acid and the neutralized neutralized water is transferred to a neutralized water storage tank. Claim 5 An ammonia gas treatment device according to claim 4, characterized by having a return pipe from downstream of the neutralization treatment device to upstream of the neutralization treatment device. Claim 6 An ammonia gas treatment device for a ship carrying liquefied ammonia as cargo or engine fuel, comprising: a decontamination device that receives one or more of ammonia gas volatilized from said cargo, ammonia gas vaporized from liquefied ammonia remaining in the engine's fuel supply line, and residual ammonia gas, absorbs said ammonia gas into fresh water to form ammonia water, and sends said ammonia water to a neutralized water storage tank; and a neutralizing agent tank that stores an organic acid and supplies said organic acid to said neutralized water storage tank, wherein said ammonia water is neutralized by said organic acid inside said neutralized water storage tank to become neutralized water. Claim 7 An ammonia gas treatment device for a ship carrying liquefied ammonia as cargo or engine fuel, comprising: a decontamination device that receives one or more of ammonia gas volatilized from said cargo, ammonia gas vaporized from liquefied ammonia remaining in the engine fuel supply line, and residual ammonia gas, absorbs said ammonia gas into fresh water to form ammonia water, and transfers said ammonia water to a neutralization water storage tank; and a neutralizing agent tank that stores an organic acid and supplies said organic acid to a neutralization treatment device, wherein said ammonia water circulates between said neutralization treatment device and said neutralization water storage tank, and said circulating ammonia water is neutralized by said organic acid to become neutralized water. Claim 8 An ammonia gas treatment device according to claim 7, characterized in that the ammonia water supplied from the decontamination device to the neutralization water storage tank is supplied via the neutralization treatment device. Claim 9 An ammonia gas treatment device according to any one of claims 1 to 8, characterized by comprising a reducing agent supply device for generating ammonia gas from the neutralized water, and a transport unit for supplying the ammonia gas generated by the reducing agent supply device to a selective reduction catalyst unit connected to the engine. Claim 10 An ammonia gas treatment device according to claim 9, characterized in that the neutralizing agent residue after ammonia gas is generated in the above-mentioned reducing agent supply device is stored as a reusable neutralizing agent. Claim 11 A method for treating ammonia gas in a vessel carrying liquefied ammonia as fuel for cargo or the engine of the vessel, wherein one or more of the ammonia gas volatilized from the cargo, ammonia gas vaporized from liquefied ammonia remaining in the engine's fuel supply line, and residual ammonia gas are received in a decontamination device; a neutralization solution, which is an aqueous solution of organic acid, is prepared from clean water and an organic acid using a neutralization solution manufacturing device; the neutralization solution is supplied to the decontamination device; within the decontamination device, the ammonia gas received by the decontamination device is absorbed into the neutralization solution and simultaneously neutralized; and the neutralized water is transferred to a neutralized water storage tank. Claim 12 A method for treating ammonia gas in a vessel carrying liquefied ammonia as cargo or engine fuel, wherein one or more of the ammonia gas volatilized from the cargo, the ammonia gas vaporized from the liquefied ammonia remaining in the engine fuel supply line, and the residual ammonia gas are received in a decontamination device; a neutralization solution, which is an aqueous solution of an organic acid composed of clean water and an organic acid, is stored in a neutralization solution tank; the neutralization solution is supplied to the decontamination device; within the decontamination device, the ammonia gas received by the decontamination device is absorbed into the neutralization solution and simultaneously neutralized; and the neutralized water is transferred to a neutralization water storage tank. Claim 13 A method for treating ammonia gas in a vessel carrying liquefied ammonia as cargo or engine fuel, wherein one or more of the ammonia gas volatilized from the cargo, ammonia gas vaporized from liquefied ammonia remaining in the engine's fuel supply line, and residual ammonia gas are received in a decontamination device; within the decontamination device, the ammonia gas received in the decontamination device is absorbed into fresh water and neutralized with an organic acid, the neutralized water is transferred to a neutralized water storage tank; the fresh water is supplied to the decontamination device; a solid organic acid is stored in a neutralizing agent tank; and the solid organic acid is supplied to the decontamination device as the organic acid. Claim 14 A method for treating ammonia gas in a vessel carrying liquefied ammonia as cargo or engine fuel, wherein one or more of the ammonia gas volatilized from the cargo, ammonia gas vaporized from liquefied ammonia remaining in the engine's fuel supply line, and residual ammonia gas are received in a decontamination device, the ammonia gas is absorbed into fresh water to form ammonia water, the ammonia water is transferred to a neutralization treatment device, an organic acid is stored in a neutralizing agent tank, the organic acid is supplied to the neutralization treatment device, and within the neutralization treatment device, the ammonia water is neutralized using the organic acid, and the neutralized water is transferred to a neutralized water storage tank. Claim 15 A method for treating ammonia gas according to claim 14, characterized by installing a return pipe from downstream of the neutralization treatment device to upstream of the neutralization treatment device. Claim 16 A method for treating ammonia gas in a vessel carrying liquefied ammonia as cargo or engine fuel, wherein one or more of the ammonia gas volatilized from the cargo, ammonia gas vaporized from liquefied ammonia remaining in the engine's fuel supply line, and residual ammonia gas are received in a decontamination device, the ammonia gas is absorbed into fresh water to form ammonia water, the ammonia water is transferred to a neutralized water storage tank, an organic acid is stored in a neutralizing agent tank, the organic acid is supplied to the neutralized water storage tank, and within the neutralized water storage tank, the ammonia water is neutralized by the organic acid to form neutralized water. Claim 17 A method for treating ammonia gas in a vessel carrying liquefied ammonia as cargo or engine fuel, wherein one or more of the ammonia gas volatilized from the cargo, ammonia gas vaporized from liquefied ammonia remaining in the engine's fuel supply line, and residual ammonia gas are received in a decontamination device, the ammonia gas is absorbed into fresh water to form ammonia water, the ammonia water is transferred to a neutralization water storage tank, an organic acid is stored in a neutralizing agent tank, the organic acid is supplied to a neutralization treatment device, the ammonia water is circulated between the neutralization treatment device and the neutralization water storage tank, and the circulating ammonia water is neutralized with the organic acid to form neutralization water. Claim 18 A method for treating ammonia gas according to claim 17, characterized in that the supply of the ammonia water from the decontamination device to the neutralization water storage tank is performed via the neutralization treatment device. Claim 19 A method for treating ammonia gas according to any one of claims 11 to 18, wherein ammonia gas is generated from the neutralized water by a reducing agent supply device, and the ammonia gas generated by the reducing agent supply device is supplied to a selective reduction catalyst unit connected to the device. Claim 20 A method for treating ammonia gas according to claim 19, characterized by storing the neutralizing agent residue after ammonia gas is generated in the above-mentioned reducing agent supply device and reusing it as a neutralizing agent. Claim 21 delete Claim 22 delete

Images