Apparatus and method for treating ammonia gas

Abstract

The present invention addresses the problem of providing an apparatus and a method for treating ammonia gas, with which ammonia water, obtained by dissolving an ammonia gas that has volatilized from a cargo or has remained in a fuel supply line of an engine in clean water, can be effectively treated on a ship without being discharged to the outside of the ship, the apparatus and method requiring no additional ammonia water supply tank. The problem is solved by: converting an ammonia gas remaining in a fuel supply line of an engine 3 to ammonia water in a detoxification device 6; introducing exhaust gas from the engine 3, urea water from a urea water tank 8, and the ammonia water generated in the detoxification device 6 into a selective reduction catalyst unit 17; and performing a denitration treatment for the exhaust gas and a detoxification treatment for the ammonia water.

Description

Ammonia gas treatment device and treatment method

[0001] The present invention relates to an ammonia gas treatment device and treatment method for a ship carrying liquefied ammonia as cargo or engine fuel, and more particularly to an ammonia gas treatment device and treatment method that can effectively treat ammonia gas volatilized from the cargo or remaining in the engine fuel supply line on board using ammonia water, which is prepared by dissolving the ammonia gas in fresh water, without discharging it overboard, and that does not require an additional ammonia water supply tank.

[0002] As described in Patent Document 1, a urea selective catalytic reduction (SCR) system is known as an exhaust gas purification device for purifying NOx (nitrogen oxides) contained in exhaust gas emitted from an engine.

[0003] The urea SCR system uses ammonia gas, which is produced when urea water injected into exhaust gas is hydrolyzed by the heat of the exhaust gas, as a reducing agent, and causes NOx to chemically react with the ammonia gas in the presence of an SCR catalyst, reducing it to nitrogen and water.

[0004] Due to the strengthening of NOx emission regulations for ships, urea SCR systems are being introduced to ships.

[0005] Meanwhile, in light of the recent global warming issue, the use of liquefied ammonia as fuel for marine propulsion engines is being considered. When liquefied ammonia is used as fuel, it is necessary to purge the fuel supply line and empty the fuel supply system to keep it within the flammable range in the event of an emergency. Furthermore, in tanks storing liquefied ammonia, because liquefied ammonia is volatile, ammonia gas known as boil-off gas is generated due to natural heat input, etc. If ammonia gas is allowed to generate, the pressure inside the tank will rise and exceed the design pressure.

[0006] Furthermore, since ammonia gas is flammable and toxic, storing it as is may have an adverse effect on the human body. Therefore, the toxicity of ammonia gas must be removed using a detoxification device. As a detoxification device, a device that dissolves ammonia gas in clean water to produce ammonia water is used.

[0007] In addition, since current environmental regulations prohibit discharging ammonia water overboard, the ammonia water recovered onboard must be treated onboard. Furthermore, since various devices and the like must be installed in a limited space onboard, a treatment method that can be performed in a small space is desirable.

[0008] In Patent Document 2, denitration is carried out by supplying liquefied ammonia as fuel to a selective catalytic reduction device.

[0009] In Patent Document 3, residual ammonia in a fuel supply system is recovered, and the recovered ammonia water is treated onboard by adjusting the concentration of the recovered ammonia water to a predetermined high level (for example, several tens of percent) and supplying it to a selective catalytic reduction (SCR) device. The ammonia component is consumed in the denitrification treatment of engine exhaust gas.

[0010] Japanese Patent Application Laid-Open No. 2020-045769 Japanese Patent Application Laid-Open No. 2022-528443 Japanese Patent Application Laid-Open No. 2022-179983

[0011] Incidentally, in Patent Document 2, the residual ammonia in the fuel supply system is not recovered, and therefore the problem of recovering the residual ammonia is not presented.

[0012] In Patent Document 3, which recovers residual ammonia in a fuel supply system, the recovered ammonia water is used to perform denitration treatment of engine exhaust gas. However, there is a risk that the recovered ammonia water may not have an adequate concentration for denitration treatment, so an additional ammonia water supply tank is provided, which requires additional space.

[0013] An object of the present invention is to provide an ammonia gas treatment device and treatment method that can effectively treat ammonia water, which is obtained by dissolving ammonia gas volatilized from cargo or remaining in an engine fuel supply line in fresh water, on board a ship without discharging it overboard, and that does not require an additional ammonia water supply tank.

[0014] Further objects of the present invention will become apparent from the following description.

[0015] The above problems are solved by the following inventions: 1. An ammonia gas treatment device for a ship that carries liquefied ammonia as fuel for cargo or the ship's engine and is equipped with a selective reduction catalyst unit, wherein exhaust gas from the ship's engine is introduced into the selective reduction catalyst unit, a urea solution serving as a reducing agent can be supplied, and a selective reduction catalyst that denitrifies the exhaust gas is disposed within the selective reduction catalyst unit, and wherein ammonia gas formed by vaporization of liquefied ammonia remaining in a fuel supply line for the ship's engine and / or ammonia gas volatilized from the cargo is dissolved in fresh water to produce ammonia water, and the ammonia water produced by the ammonia water treatment device is supplied to the selective reduction catalyst unit, and the ammonia water is detoxified. 2. 2. The ammonia gas treatment device described in 1, wherein a supply path for the ammonia water to the selective reduction catalyst unit reaches the selective reduction catalyst unit independently of a supply path for the urea water to the selective reduction catalyst unit, the urea water and the ammonia water can be simultaneously supplied to the selective reduction catalyst unit through a nozzle, and the nozzle is a three-fluid nozzle having a flow path connected to an air supply source and supplying air for diffusing the urea water and / or the ammonia water, a flow path connected to the urea water supply path and spraying the urea water, and a flow path connected to the ammonia water supply path and spraying the ammonia water, and is disposed upstream within the selective reduction catalyst unit.3. The ammonia gas treatment device according to item 1, characterized in that a supply path for the ammonia water to the selective reduction catalyst unit leads to the selective reduction catalyst unit independently of a supply path for the urea water to the selective reduction catalyst unit, the urea water and the ammonia water can be simultaneously supplied to the selective reduction catalyst unit through a nozzle, the nozzle consisting of a first nozzle and a second nozzle, the first nozzle is a two-fluid nozzle having two flow paths, a flow path connected to the air supply source for supplying air and a flow path connected to the urea water supply path for spraying the urea water, and is arranged upstream within the selective reduction catalyst unit, and the second nozzle is a two-fluid nozzle having two flow paths, a flow path connected to the air supply source for supplying air and a flow path connected to the ammonia water supply path for spraying the ammonia water, and is arranged upstream within the selective reduction catalyst unit. 2. The ammonia gas treatment device according to claim 1, wherein a supply path for the ammonia water to the selective reduction catalyst unit leads to the selective reduction catalyst unit independently of a supply path for the urea water to the selective reduction catalyst unit, the urea water and the ammonia water can be simultaneously supplied to the selective reduction catalyst unit through a nozzle, the nozzle comprising a first nozzle and a second nozzle, the first nozzle being a two-fluid nozzle having two flow paths, a flow path connected to the air supply source for supplying air and a flow path connected to the urea water supply path for spraying the urea water, and is arranged upstream within the selective reduction catalyst unit, the second nozzle being a two-fluid nozzle having two flow paths, a flow path connected to the air supply source for supplying air and a flow path connected to the ammonia water supply path for spraying the ammonia water, and is arranged in an exhaust receiver through which the exhaust gas passes prior to the selective reduction catalyst unit, and the air and the ammonia water are supplied into the selective reduction catalyst unit through this exhaust receiver.5. The ammonia gas treatment device described in 1, characterized in that a supply path for the ammonia water to the selective reduction catalyst unit merges with a supply path for the urea water to the selective reduction catalyst unit before reaching the selective reduction catalyst unit, either the urea water or the ammonia water is supplied to the selective reduction catalyst unit through a nozzle, and the nozzle is a two-fluid nozzle having two flow paths: a flow path connected to an air supply source for supplying air, and a flow path connected by the merger of the urea water supply path and the ammonia water supply path for spraying the urea water or the ammonia water, and is located upstream within the selective reduction catalyst unit. 6. The ammonia gas treatment device according to any one of items 1 to 4, further comprising: a meter for measuring the density of the ammonia water; simultaneously supplying the urea water and the ammonia water to the selective reduction catalyst unit; converting the density of the ammonia water measured by the meter for measuring the density of the ammonia water into a concentration of the ammonia water and calculating the molar equivalent of the ammonia water to be supplied to the selective reduction catalyst unit from this concentration; calculating the molar equivalent of the urea water to be supplied to the selective reduction catalyst unit from the known concentration of the urea water; adding together the molar equivalent of the ammonia water and the molar equivalent of the urea water supplied to the selective reduction catalyst unit and adjusting the flow rates of the urea water and the ammonia water according to the combined molar equivalent, and performing denitrification treatment of the exhaust gas as the detoxification treatment. 6. The ammonia gas treatment device according to any one of 1 to 5, wherein a supply path for the ammonia water to the selective reduction catalyst unit is joined with liquefied ammonia supplied from a fuel supply device of the ship, the ammonia water and the liquefied ammonia are mixed to form ammonia water, and the ammonia water is supplied to the selective reduction catalyst unit; the device further comprises an instrument for measuring a density of the ammonia water obtained by mixing the ammonia water and the liquefied ammonia; the device calculates a molar equivalent of the ammonia water to be supplied to the selective reduction catalyst unit from the density of the ammonia water measured by the instrument for measuring the density of the ammonia water, and adjusts a flow rate of the ammonia water according to the calculated molar equivalent, thereby performing a denitrification treatment of the exhaust gas as the detoxification treatment.8. The ammonia gas treatment device according to any one of items 1 to 5, further comprising an instrument for measuring a leak ammonia concentration in the exhaust gas, measuring an exhaust gas flow rate of the engine, calculating an amount of leak ammonia from the measured exhaust gas flow rate and the leak ammonia concentration, or from an exhaust gas flow rate calculated from load information from an output of the engine and the leak ammonia concentration, and adjusting the flow rate of the urea water or the ammonia water so that the sum of the amount of ammonia supplied into the selective reduction catalyst unit by the urea water and / or the ammonia water and the amount of leak ammonia becomes the amount of ammonia treated in the selective reduction catalyst unit, thereby performing denitrification treatment of the exhaust gas as the detoxification treatment. 9. The ammonia gas treatment device according to any one of items 1 to 5, further comprising an ammonia slip catalyst disposed within the selective reduction catalyst unit, and performing detoxification treatment of the ammonia water supplied to the selective reduction catalyst unit by the ammonia slip catalyst. 10. 1. A method for treating ammonia gas in a ship that is loaded with liquefied ammonia as fuel for cargo or the ship's engine and is equipped with a selective reduction catalyst unit, comprising: a selective reduction catalyst into which exhaust gas from the ship's engine is introduced and into which a urea solution serving as a reducing agent can be supplied, and which performs a denitrification treatment of the exhaust gas; a detoxification device dissolves ammonia gas and / or ammonia gas vaporized from liquefied ammonia remaining in a fuel supply line of the ship's engine, or ammonia gas volatilized from the cargo, in fresh water to produce ammonia water; and ammonia water produced by the detoxification device is supplied to the selective reduction catalyst unit, and the ammonia water is detoxified.11. The method for treating ammonia gas described in paragraph 10, characterized in that the urea water and the ammonia water are simultaneously supplied to the selective reduction catalyst unit, the density of the ammonia water is measured, the measured density of the ammonia water is converted to a concentration of the ammonia water, and from this concentration, a molar equivalent of the ammonia water to be supplied to the selective reduction catalyst unit is calculated, from the known concentration of the urea water, the molar equivalent of the ammonia water to be supplied to the selective reduction catalyst unit and the molar equivalent of the urea water are added together, the flow rates of the urea water and the ammonia water are adjusted according to the added molar equivalent, and a denitrification treatment of the exhaust gas is performed as the detoxification treatment. 12. The method for treating ammonia gas described in 10, characterized in that liquefied ammonia supplied from a fuel supply device of the ship is merged into a supply path for the ammonia water to the selective catalytic reduction unit, the ammonia water and the liquefied ammonia are mixed to form ammonia water, and the ammonia water is supplied to the selective catalytic reduction unit, the density of the ammonia water obtained by mixing the ammonia water and the liquefied ammonia is measured, a molar equivalent of the ammonia water to be supplied to the selective catalytic reduction unit is calculated from the measured density of the ammonia water, a flow rate of the ammonia water is adjusted according to the calculated molar equivalent, and a denitrification treatment of the exhaust gas is performed as the detoxification treatment. 11. The method for treating ammonia gas described in item 10, characterized in that: an instrument is provided that measures a leak ammonia concentration in the exhaust gas; an exhaust gas flow rate of the engine is measured, and an amount of leak ammonia is calculated from the measured exhaust gas flow rate and the leak ammonia concentration, or from the exhaust gas flow rate calculated from load information from an output of the engine and the leak ammonia concentration; and a flow rate of the urea water or the ammonia water is adjusted so that the sum of the amount of ammonia supplied into the selective reduction catalyst unit by the urea water and / or the ammonia water and the amount of leak ammonia becomes the amount of ammonia treated in the selective reduction catalyst unit, thereby performing a denitrification treatment of the exhaust gas as the detoxification treatment.14. The method for treating ammonia gas according to 10, wherein an ammonia slip catalyst is provided in the selective catalytic reduction unit, and the ammonia water supplied to the selective catalytic reduction unit is detoxified by the ammonia slip catalyst.

[0016] According to the present invention, it is possible to provide an ammonia gas treatment device and treatment method that can effectively treat ammonia water, which is obtained by dissolving ammonia gas volatilized from cargo or remaining in an engine fuel supply line in fresh water, on board a ship without discharging it overboard, and that does not require an additional ammonia water supply tank.

[0017] FIG. 1 is a block diagram showing the configuration of a fuel supply device for a ship to which the ammonia gas treatment device of the present invention is applied; FIG. 2 is a block diagram showing the configuration of an ammonia gas treatment device of a first embodiment of the present invention; FIG. 3 is a block diagram showing the configuration of an ammonia gas treatment device of a second embodiment of the present invention; FIG. 4 is a schematic cross-sectional view showing a first structure of a nozzle and a selective reduction catalyst unit applied to the ammonia gas treatment device of the present invention; FIG. 5 is a block diagram showing the configuration of an ammonia gas treatment device of a fourth embodiment of the present invention;

[0018] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Various features shown in each of the following embodiments can be combined with each other. The present invention is an ammonia gas treatment device for a ship that carries liquefied ammonia as cargo or fuel for the ship's engine, and an ammonia gas treatment method performed in this ammonia gas treatment device.

[0019] [Configuration of a fuel supply system for a ship] Fig. 1 is a block diagram showing the configuration of a fuel supply system for a ship to which an ammonia gas treatment device of the present invention is applied. In Fig. 1, the liquid flow path is shown by a solid line and the gas flow path is shown by a dotted line.

[0020] As shown in Fig. 1, the fuel supply system of the ship is equipped with a selective catalytic reduction (SCR) unit 17. A selective catalytic reduction (SCR) is installed in the selective catalytic reduction unit 17, and NOx in the engine exhaust gas is reduced by selective catalytic reduction (SCR). Ｘ A denitration treatment is carried out by reacting the nitrate with ammonia gas.

[0021] The selective catalytic reduction unit 17 is connected to an exhaust duct of the engine 3, which is the engine of the ship, and engine exhaust gas is introduced into it. In addition, urea water, which is a reducing agent stored in a urea water tank 8, is supplied to the selective catalytic reduction unit 17. Although not shown, the exhaust duct of the engine 3 may be provided with a meter (ammonia gas concentration meter) that measures the leak ammonia concentration in the engine exhaust gas, and further, a device (gas flow meter) that measures the gas flow rate of the engine exhaust gas may be provided.

[0022] The urea water stored in the urea water tank 8 is supplied to the selective catalytic reduction unit 17 by a urea water pump 15a via a urea water transport pipe 15, which serves as a urea water supply path. The urea water is hydrolyzed in the high-temperature selective catalytic reduction unit 17 to generate ammonia gas. This ammonia gas denitrifies the engine exhaust gas. The denitrified exhaust gas is then discharged into the atmosphere.

[0023] Meanwhile, in this fuel supply device, liquefied ammonia fuel is supplied from a liquefied ammonia tank 1 through a fuel supply line (a fuel supply device 2 and a fuel pipe 4) to an engine 3. The engine 3 is driven by burning the liquefied ammonia fuel.

[0024] In this fuel supply device, ammonia gas and / or ammonia gas (residual gas) vaporized from liquefied ammonia introduced from the fuel supply line, ammonia gas and / or ammonia gas vaporized from liquefied ammonia remaining in the fuel supply device 2, or ammonia gas (boil-off gas) introduced from a cargo ammonia tank (not shown) are detoxified by a detoxification device 6.

[0025] The fuel supply line is made up of the fuel supply device 2 and the fuel piping 4, and is a path for supplying liquefied ammonia fuel to the engine 3 via the fuel piping 4 by a compressor, a pump, a heat exchanger, etc., provided in the fuel supply device 2. Note that the fuel supply device 2 does not have to be provided if it is unnecessary. Furthermore, the fuel piping 4 may be made up of a supply piping that supplies ammonia gas from the fuel supply device 2 to the engine 3, and a return piping that returns excess ammonia gas from the engine 3 to the fuel supply device 2. Although not shown, on the liquefied ammonia tank 1 side of the fuel supply device 2 and the engine 3 side of the fuel piping 4, on-off valves that can close 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 may be provided.

[0026] Liquefied ammonia tank 1 stores ammonia, which is a fuel used for engine 3 and the like. Ammonia is stored as liquefied ammonia inside liquefied ammonia tank 1. In order to maintain the liquefied ammonia in a liquid state, the interior of liquefied ammonia tank 1 is maintained at high pressure or low temperature. When a large amount of liquefied ammonia is loaded onto a ship for a long voyage or the like, a full-refrigerated (atmospheric pressure) or semi-refrigerated (semi-pressurized) type liquefied ammonia tank 1 is mainly used, which has thin walls and is easy to process. A suction pump 1a is installed inside liquefied ammonia tank 1, and this suction pump 1a sends the stored liquefied ammonia to a pipe leading to fuel supply device 2.

[0027] The cargo ammonia tank (not shown) stores liquefied ammonia as cargo, rather than fuel to be used for the engine 3, etc. As with the liquefied ammonia tank 1, the interior of the cargo ammonia tank is maintained at high pressure or low temperature in order to maintain the liquefied ammonia in a liquid state within the cargo ammonia tank. When a large amount of liquefied ammonia is loaded onto a ship, a full-refrigerated (atmospheric pressure) or semi-refrigerated (semi-pressurized) cargo ammonia tank is mainly used, which has a thin wall and is easy to process.

[0028] Liquefied ammonia fuel is supplied to the engine 3 from a liquefied ammonia tank 1 by a fuel supply device 2. Pilot fuel may also be supplied to the engine 3 from a heavy oil tank (not shown). The pilot fuel is burned together with the ammonia fuel when the ammonia fuel starts to burn, raising the temperature inside the combustion chamber and ensuring good combustion of the ammonia fuel. The supply of pilot fuel may be stopped when the temperature inside the combustion chamber rises to a state where combustion using only ammonia fuel is possible. Furthermore, if the engine 3 is capable of burning only ammonia fuel from the start, pilot fuel is not necessary. Furthermore, the engine 3 may be a dual-fuel engine using liquefied ammonia fuel and a fossil fuel such as heavy oil. The dual-fuel engine can selectively switch between a mode in which liquefied ammonia fuel is supplied as the main fuel and a fossil fuel such as heavy oil is supplied as an ignition source, and a fossil fuel mode in which operation is performed using only fossil fuel.

[0029] Nitrogen gas is supplied to the fuel pipe 4 from a nitrogen gas supply device 51 via a purge gas supply valve 50. This nitrogen gas is also supplied to the fuel supply device 2 via the fuel pipe 4. This nitrogen gas is an inert gas that purges ammonia gas and / or ammonia gas vaporized from liquefied ammonia remaining in the fuel pipe 4 and the fuel supply device 2 when the engine 3 is started, stopped, or in an emergency stop.

[0030] When the engine 3 is started, stopped, or stopped in an emergency, ammonia gas and / or ammonia gas vaporized from residual liquefied ammonia is introduced from the fuel pipe 4 into the abatement device 6 via the gas-liquid separator 4a and the purge gas discharge valve 5. Also, when the engine 3 is started, stopped, or stopped in an emergency, or during maintenance, ammonia gas and / or ammonia gas vaporized from residual liquefied ammonia is introduced from the fuel supply device 2 into the abatement device 6 via the on-off valve 2a. The fuel supply device 2 includes a pump and a gas-liquid separator at an outlet for the ammonia gas and / or ammonia gas vaporized from residual liquefied ammonia. The gas introduced from the fuel pipe 4 and the fuel supply device 2 into the abatement device 6 is a mixture of ammonia gas and a purge gas, such as nitrogen. In this embodiment, the treatment is performed on the ammonia component in the mixture. When ammonia gas is introduced into the abatement 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 pipe 4 is closed by an on-off valve. Ammonia gas (boil-off gas) is also introduced from the cargo ammonia tank into the abatement device 6. The nitrogen gas used for purging is released into the atmosphere via the abatement device 6.

[0031] Fresh water, for example, produced by an onboard water generator and stored in a fresh water tank 22, is introduced into the detoxification device 6 by a water supply pump 22a. Here, the fresh water is water that contains as few impurities and additives as possible, such as distilled water, ion-exchanged water, or filtered water.

[0032] The abatement device 6 is configured to include a water-sealed tank and a scrubber tank. The mixed gas of ammonia gas and nitrogen introduced into the abatement device 6 is introduced into the water-sealed tank and the scrubber tank.

[0033] In the water-sealed tank or scrubber tank, the introduced mixed gas of ammonia gas and nitrogen is passed through fresh water, or fresh water is sprayed from above, to dissolve the ammonia component in the fresh water, thereby producing ammonia water. The nitrogen gas used for purging is released into the atmosphere from the abatement device 6.

[0034] As the detoxification device 6, it is preferable to use a water-sealed tank or a scrubber tank.

[0035] When a water seal tank is used, ammonia gas is introduced from the bottom of the water seal tank and absorbed into the fresh water stored in the water seal tank to become ammonia water. When a scrubber tank is used, ammonia gas is introduced from the bottom of the scrubber tank and comes into contact with the fresh water sprayed from the top of the scrubber tank, where it is absorbed into the fresh water to become ammonia water.

[0036] More preferably, a water seal tank and a scrubber tank are provided in parallel, and ammonia gas that has re-volatilized from the ammonia water produced in the water seal tank and ammonia gas that has not been completely absorbed in the water seal tank are introduced into the lower part of the scrubber tank. In the scrubber tank, it is preferable to spray the ammonia water accumulated in the scrubber tank again from the top of the scrubber tank and circulate it, thereby further absorbing the ammonia gas that has re-volatilized from the ammonia water in the scrubber tank and the ammonia gas that has not been completely absorbed. By providing the water seal tank and the scrubber tank in parallel, ammonia gas can be reliably absorbed and its release overboard can be reliably prevented.

[0037] Even when only a water seal tank is used as the abatement device 6, a circulation mechanism can be provided to reintroduce the ammonia gas that has evaporated from the ammonia water and the ammonia gas that has not been completely absorbed by the fresh water into the lower part of the water seal tank, thereby ensuring the absorption of the ammonia gas and preventing the ammonia gas from being released overboard. Even when only a scrubber tank is used as the abatement device 6, a circulation mechanism can be provided to spray the ammonia water accumulated in the scrubber tank from the upper part of the scrubber tank again to further absorb the ammonia gas that has evaporated from the ammonia water and the ammonia gas that has not been completely absorbed by the fresh water, thereby ensuring the absorption of the ammonia gas and preventing the ammonia gas from being released overboard.

[0038] The wastewater (ammonia water) from the ammonia removal device 6 is sent by gravity to the ammonia water tank 7, and is temporarily stored in the ammonia water tank 7. The ammonia water tank 7 is preferably a sealed pressurized tank so that ammonia gas does not volatilize from the ammonia water stored therein. When the ammonia water tank 7 is not a sealed pressurized tank, the ammonia gas volatilized from the ammonia water stored therein is preferably returned to the ammonia removal device 6 (a water seal tank and / or a scrubber tank).

[0039] The ammonia water temporarily stored in the ammonia water tank 7 is detoxified by denitration in the selective catalytic reduction unit 17. The ammonia water stored in the ammonia water tank 7 can be supplied to the selective catalytic reduction unit 17 by an ammonia water pump 18a via an ammonia water transport pipe 18, which serves as an ammonia water supply path. The ammonia water generates ammonia gas in the high-temperature selective catalytic reduction unit 17, and this ammonia gas converts the NOx in the engine exhaust gas into ammonia gas. Ｘ Alternatively, the ammonia gas generated in the selective catalytic reduction unit 17 is rendered harmless by an ammonia slip catalyst (ASC) installed in the selective catalytic reduction unit 17. Note that the denitrification treatment in the selective catalytic reduction unit 17 is performed in both an operation mode mainly using liquefied ammonia fuel and a fossil fuel mode.

[0040] The supply path of the ammonia water from the ammonia water tank 7 to the selective reduction catalyst unit 17 and the supply path of the urea water from the urea water tank 8 to the selective reduction catalyst unit 17 will be described in each embodiment below. The structure of the selective reduction catalyst unit 17 and the structure of the nozzles that supply the urea water and the ammonia water to the selective reduction catalyst unit 17 will also be described below.

[0041] 2 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 in this ammonia gas treatment apparatus.

[0042] In the ammonia gas treatment device of this embodiment, the liquid level of the urea water stored in the urea water tank 8 is measured by an LIT 8a (hereinafter referred to as the "liquid level meter 8a"), and the urea water is sent from the urea water tank 8 to the urea water transport pipe 15 by a urea water pump 15a.

[0043] The urea water delivered from the urea water tank 8 can be supplied to the selective reduction catalyst unit 17 via a first on-off valve 16, a urea water flow rate control valve 19, and an FT 20 (hereinafter referred to as "urea water flow meter 20") provided in the urea water transport pipe 15. The urea water flow rate control valve 19 is operated in accordance with the measurement result of the urea water flow meter 20.

[0044] The urea water transport pipe 15 branches between the urea water pump 15a and the urea water flow rate adjustment valve 19, and the branch pipe returns to the urea water tank 8 via a urea water circulation valve 21. The urea water circulation valve 21 is a back pressure valve (regulator). The urea water circulation valve 21 opens when the pressure in the urea water transport pipe 15 exceeds a predetermined pressure, and limits the pressure in the urea water transport pipe 15 to a pressure equal to or lower than the predetermined pressure. The urea water circulation valve 21 may also be a pressure reducing valve.

[0045] The urea water transport pipe 15 is joined with an ammonia water transport pipe 18, which serves as a supply path for ammonia water, before reaching the selective reduction catalyst unit 17. The piping after the urea water transport pipe 15 and the ammonia water transport pipe 18 are joined together becomes a urea water or ammonia water transport pipe 28.

[0046] The liquid level of the ammonia water stored in the ammonia water tank 7 is measured by an LIT 7a (hereinafter referred to as "liquid level gauge 7a"), and the ammonia water is pumped from the ammonia water tank 7 to an ammonia water transport pipe 18 by an ammonia water pump 18a.

[0047] The ammonia water delivered from the ammonia water tank 7 passes through a second on-off valve 9 provided in an ammonia water transport pipe 18, an FD10 (hereinafter referred to as a "flow rate / density meter 10") which is an instrument for measuring the density of ammonia water, an FT11 (hereinafter referred to as an "ammonia water flow rate meter 11"), and a third on-off valve 12, and is supplied to the selective reduction catalyst unit 17. The flow rate / density meter 10 is a Coriolis flow rate meter, and can measure the flow rate and density of ammonia water.

[0048] The ammonia water transport pipe 18 branches between the flow rate / density meter 10 and the ammonia water flow meter 11, and the branch pipe returns to the ammonia water tank 7 via an ammonia water circulation valve 14. The ammonia water circulation valve 14 is a back pressure valve (regulator). The ammonia water circulation valve 14 opens when the pressure in the ammonia water transport pipe 18 exceeds a predetermined pressure, and limits the pressure in the ammonia water transport pipe 18 to a predetermined pressure or less. The ammonia water circulation valve 14 may be a pressure reducing valve.

[0049] The ammonia water transport pipe 18 is joined with the urea water transport pipe 15 before reaching the selective reduction catalyst unit 17. The piping after the urea water transport pipe 15 and the ammonia water transport pipe 18 are joined becomes a urea water or ammonia water transport pipe 28.

[0050] The urea water or ammonia water transport pipe 28 is supplied with air from an air supply source 25, which is supplied to the selective catalytic reduction unit 17 together with the urea water or ammonia water. The pressure inside the urea water or ammonia water transport pipe 28 is measured by a PT 24 (hereinafter referred to as a "pressure gauge 24"). The temperature inside the selective catalytic reduction unit 17 is measured by a TT 26 (hereinafter referred to as a "thermometer 26"). The ammonia water circulation valve 14 and the urea water circulation valve 21 may be flow rate adjustment valves that are operated in accordance with the measurement result of the pressure gauge 24. The flow rates of the urea water and ammonia water may be adjusted by adjusting the rotation speed of the pump using an inverter in accordance with the load on the engine 3.

[0051] Air and urea water, or air and ammonia water, are supplied into the selective catalytic reduction unit 17 through a nozzle 13. The structure of the selective catalytic reduction unit 17 and the shape of the nozzle 13 will be described later.

[0052] The detoxification device 6, the ammonia water tank 7, and the urea water tank 8 are installed outside the engine room of the ship, and the selective catalytic reduction unit 17 is installed inside the engine room of the ship.

[0053] In this embodiment, in water areas subject to Tier 3 regulations on exhaust gas from marine diesel engines, urea water is supplied to the selective catalytic reduction unit 17 to perform denitration treatment, and in water areas subject to Tier 2 regulations, ammonia water is supplied to the selective catalytic reduction unit 17 to perform ammonia water detoxification treatment. In the ammonia water detoxification treatment, it is not necessary to denitrify all of the nitrogen oxides (NOx) in the engine exhaust gas.

[0054] When ammonia water is supplied to the selective reduction catalyst unit 17, the concentration of the ammonia water is calculated from the density of the ammonia water measured by the flow rate / density meter 10, and the output of the ammonia water pump 18a is adjusted according to this concentration. This makes it possible to manage the concentration of the ammonia water supplied to the selective reduction catalyst unit 17, and makes it possible for the entire amount of ammonia water supplied to be detoxified in the selective reduction catalyst unit 17.

[0055] The supply of urea water and / or ammonia water to this ammonia gas treatment device is carried out, for example, as follows.

[0056] (1) Supply in Tier 3 Sea Areas In the ammonia gas treatment device of this embodiment, in sea areas subject to Tier 3 regulations, if the engine 3 is running and the temperature inside the selective catalytic reduction unit 17 measured by the thermometer 26 is sufficiently high, a reducing agent is supplied to the selective catalytic reduction unit 17 to perform denitrification treatment. If ammonia water generated by the detoxification device 6 is stored as the reducing agent, this ammonia water is supplied, and if this ammonia water is insufficient, urea water is preferably supplied. By prioritizing the treatment of ammonia water, the amount of urea water consumed can be reduced. In addition, it is also possible to reduce the capacity of the urea water tank.

[0057] The amount of ammonia water supplied is adjusted by measuring the density of the ammonia water in the ammonia water transport pipe 18 with the flow rate / density meter 10, converting it into an ammonia water concentration, and operating the third on-off valve 12 in accordance with this ammonia water concentration. Note that the relationship between the concentration and flow rate of the ammonia water supplied and the amount of nitrogen oxides (NOx) in the engine exhaust gas to be treated is known in advance.

[0058] If the water level of the ammonia water in the ammonia water tank 7 is equal to or higher than the low level (L), the ammonia water pump 18a is started, and the second on-off valve 9 and the third on-off valve 12 are opened to supply the ammonia water.

[0059] The flow rate of the ammonia water is adjusted so that the amount of ammonia water supplied to the selective catalytic reduction unit 17 is a necessary and sufficient supply amount, converted from the molar equivalent of ammonia water, for denitration treatment in the selective catalytic reduction unit 17. Note that in an operation mode using liquefied ammonia fuel as the main fuel, leaked ammonia in engine exhaust gas enters the selective catalytic reduction unit 17, and therefore the amount of leaked ammonia is set to an amount obtained by subtracting the amount of leaked ammonia. In this case, it is preferable to provide an instrument (ammonia gas concentration meter) that measures the leaked ammonia concentration in the engine exhaust gas. That is, the amount of leaked ammonia is calculated from the exhaust gas flow rate calculated from the output of the engine 3 using load information and the leaked ammonia concentration measured by the instrument. The load information is the relationship between the output of the engine 3 and the exhaust gas flow rate, and is obtained in advance. The exhaust gas flow rate is calculated from the output of the engine 3 based on this load information. The load information varies depending on whether the operating mode is primarily liquefied ammonia fuel or fossil fuel, and whether the navigation area is Tier 3 or Tier 2, and is therefore calculated for each case. Alternatively, an instrument (gas flow meter) measuring the exhaust gas flow rate of the engine 3 may be provided, and the amount of leaked ammonia may be calculated from the exhaust gas flow rate measured by the instrument and the leaked ammonia concentration. When urea water and ammonia water are supplied simultaneously, the amount of leaked ammonia is subtracted from the amount of ammonia supplied to the selective catalytic reduction unit 17 by the ammonia water, and the flow rate of the ammonia water is adjusted so that this amount of ammonia is supplied by the ammonia water. The ammonia supplied by the urea water supplements the ammonia amount necessary and sufficient for the denitrification treatment of the exhaust gas in the selective catalytic reduction unit 17. The supply of ammonia by the urea water refers to the hydrolysis of the urea water by the heat of the exhaust gas in the selective catalytic reduction unit 17 to generate ammonia.That is, when urea water and ammonia water are supplied simultaneously, the flow rate of the ammonia water is adjusted so that the sum of the amount of ammonia supplied into the selective reduction catalyst unit 17 by the urea water and the ammonia water and the amount of leaked ammonia is equal to the amount of ammonia treated in the selective reduction catalyst unit 17, and denitration of the exhaust gas is performed as detoxification treatment. When only urea water is supplied, the amount of leaked ammonia is subtracted from the amount of ammonia supplied into the selective reduction catalyst unit 17 by the urea water, and the flow rate of the urea water is adjusted so that this amount of ammonia is supplied by the urea water. By adjusting the flow rate in this way, the amount of ammonia supplied into the selective reduction catalyst unit 17 is adjusted to an amount necessary and sufficient for denitration of the exhaust gas. That is, when only urea water is supplied, the flow rate of the urea water is adjusted so that the sum of the amount of ammonia supplied into the selective reduction catalyst unit 17 by the urea water and the amount of leaked ammonia is equal to the amount of ammonia treated in the selective reduction catalyst unit 17, and denitration of the exhaust gas is performed. It is also possible to measure the amount of nitrogen oxides (NOx) in the engine exhaust gas and adjust the flow rate of the ammonia water in accordance with the measurement results.

[0060] When the water level of the ammonia water in the ammonia water tank 7 falls below the minimum level (LL), the ammonia water pump 18a is stopped to stop the supply of ammonia water.

[0061] In this embodiment, when urea water is supplied, the ammonia water pump 18a is stopped, the urea water pump 15a is started, the first on-off valve 16 is opened, the supply of urea water is started, and the flow rate of the urea water is adjusted so that the amount of urea water supplied is a necessary and sufficient supply amount for the denitrification treatment in the selective reduction catalyst unit 17, converted from the molar equivalent of urea water.

[0062] Since the concentration of the urea water is known, the molar equivalent of the urea water to be supplied can be calculated from this concentration. That is, the amount of urea water to be supplied can be adjusted by adjusting the urea water flow control valve 19 while measuring the flow rate of the urea water in the urea water transport pipe 15 with the urea water flow meter 20 according to the molar equivalent of the urea water in the urea water transport pipe 15. Note that the amount of nitrogen oxides (NOx) in engine exhaust gas may be measured, and the urea water flow control valve 19 may be adjusted according to the measurement result.

[0063] (2) Supply in Tier 2 Regulation Sea Areas In Tier 2 regulation sea areas, only ammonia water is supplied for detoxification or denitrification treatment. That is, in Tier 2 regulation sea areas, the urea water pump 15a is stopped, and the supply of urea water is stopped.

[0064] If the water level of the ammonia water in the ammonia water tank 7 is equal to or higher than the low level (L), the ammonia water pump 18a is started, and the second on-off valve 9 and the third on-off valve 12 are opened to supply the ammonia water.

[0065] The flow rate of the ammonia water is adjusted so that the amount of ammonia water supplied to the selective catalytic reduction unit 17 is equal to or less than the amount required for denitration treatment in the selective catalytic reduction unit 17, calculated from the molar equivalent of ammonia water. In an operating mode mainly using liquefied ammonia fuel, leaked ammonia in engine exhaust gas enters the selective catalytic reduction unit 17, and therefore the amount of ammonia water supplied is an amount obtained by subtracting the amount of leaked ammonia. In this case, it is preferable to provide an instrument (ammonia gas concentration meter) that measures the leaked ammonia concentration in the engine exhaust gas. That is, the amount of leaked ammonia is calculated from the exhaust gas flow rate calculated from load information based on the output of the engine 3 and the leaked ammonia concentration measured by the instrument. Alternatively, an instrument (gas flow meter) that measures the exhaust gas flow rate of the engine 3 may be further provided, and the amount of leaked ammonia may be calculated from the exhaust gas flow rate measured by the instrument and the leaked ammonia concentration. In Tier 2 regulation sea areas, only ammonia water is supplied, so the amount of leaked ammonia is subtracted from the amount of ammonia supplied into the selective reduction catalyst unit 17 by ammonia water, and the flow rate of the ammonia water is adjusted so that this amount of ammonia is supplied by ammonia water. By adjusting the flow rate in this way, the amount of ammonia supplied into the selective reduction catalyst unit 17 is adjusted to an amount that is within the denitration treatment capacity of the selective reduction catalyst unit 17. In other words, the flow rate of ammonia water is adjusted so that the sum of the amount of ammonia supplied into the selective reduction catalyst unit 17 by ammonia water and the amount of leaked ammonia becomes the amount of ammonia treated by the selective reduction catalyst unit 17, and denitration treatment of the exhaust gas is performed as detoxification treatment.

[0066] Furthermore, when an ammonia slip catalyst (ASC) 17c (described later) is used in combination, the flow rate of the ammonia water is adjusted so that the amount of ammonia water supplied to the selective reduction catalyst unit 17 is equal to or less than the processing capacity of the ammonia slip catalyst (ASC) 17c, calculated from the molar equivalent of ammonia water.

[0067] As described above, the supply amount of ammonia water is adjusted by converting the density of ammonia water in the ammonia water transport pipe 18 measured by the flow rate / density meter 10 into an ammonia water concentration, and operating the third on-off valve 12 in accordance with the ammonia water concentration while measuring the flow rate of ammonia water flowing in the ammonia water transport pipe 18 by the flow rate / density meter 10. Note that the relationship between the concentration and flow rate of the ammonia water to be supplied and the amount of nitrogen oxides (NOx) in the engine exhaust gas to be treated is known in advance.

[0068] When the water level of the ammonia water in the ammonia water tank 7 falls below the minimum level (LL), the ammonia water pump 18a is stopped to stop the supply of ammonia water.

[0069] Second Embodiment Fig. 3 is a block diagram showing the configuration of an ammonia gas treatment apparatus according to a second embodiment of the present invention. An ammonia gas treatment method according to the second embodiment of the present invention is carried out in this ammonia gas treatment apparatus.

[0070] As shown in Fig. 3, this embodiment is the same as the first embodiment (Fig. 2) except that a mixer 29 for mixing additional liquefied ammonia with the ammonia water sent from the abatement device 6 and an FD10b (hereinafter referred to as "second flow rate / density meter 10b") which is a meter for measuring the density of the ammonia water are provided. The second flow rate / density meter 10b is a Coriolis flow meter and can measure the flow rate and density of the ammonia water after the additional liquefied ammonia has been mixed.

[0071] In this ammonia gas treatment device, liquefied ammonia supplied from the fuel supply device 2 joins with ammonia water at a position downstream of the third on-off valve 12 of the ammonia water transport pipe 18. The liquefied ammonia is supplied from the fuel supply device 2 to the ammonia water transport pipe 18 via a liquefied ammonia back pressure valve (regulator) 31 and a liquefied ammonia flow meter 32.

[0072] The mixer 29 receives the ammonia water mixed with the liquefied ammonia, and mixes the liquefied ammonia and the ammonia water to produce ammonia water. Cooling water for cooling the ammonia water transport pipe 18 from the outside is supplied to the mixer 29, and the cooling ensures good mixing. The ammonia water transport pipe 18, to which the ammonia water passed through the mixer 29 is sent, passes through a second flow rate / density meter 10b and a check valve 30, and merges with the urea water transport pipe 15. The piping after the urea water transport pipe 15 and the ammonia water transport pipe 18 merges becomes the urea water or ammonia water transport pipe 28.

[0073] A check valve 33 is provided downstream of the urea water flow meter 20 provided in the urea water transport pipe 15 .

[0074] In this embodiment, in water areas subject to Tier 3 regulations on exhaust gas from marine diesel engines, urea water or ammonia water is supplied to the selective catalytic reduction unit 17 to perform denitration treatment, and in water areas subject to Tier 2 regulations, ammonia water is supplied to the selective catalytic reduction unit 17 to perform ammonia water detoxification treatment. In ammonia water detoxification treatment, it is not necessary to denitrify all of the nitrogen oxides (NOx) in the engine exhaust gas.

[0075] When the concentration and / or flow rate of ammonia water is insufficient during denitration treatment, the liquefied ammonia delivery pressure from the fuel supply device 2 is increased, and the liquefied ammonia is mixed with the ammonia water via the liquefied ammonia back pressure valve 31 and the liquefied ammonia flow meter 32. The supply amount of liquefied ammonia is adjusted by measuring the flow rate of liquefied ammonia with the liquefied ammonia flow meter 32 and measuring the flow rate and density of ammonia water upstream and downstream of the mixer 29 with the flow rate / density meter 10 and the second flow rate / density meter 10b, while adjusting the liquefied ammonia delivery pressure from the fuel supply device 2 and adjusting the flow rate through the liquefied ammonia back pressure valve 31. By mixing the liquefied ammonia, the ammonia water supplied to the selective reduction catalyst unit 17 has a concentration sufficient for denitration treatment. In this case, the consumption of urea water can be reduced.

[0076] The supply of urea water and / or ammonia water to this ammonia gas treatment device is carried out, for example, as follows.

[0077] (1) Supply in Tier 3 Sea Areas In the ammonia gas treatment device of this embodiment, the supply of reducing agent in Tier 3 sea areas is the same as in the first embodiment ( FIG. 2 ). However, in this embodiment, when the concentration of ammonia water generated by the abatement device 6 is insufficient, additional liquefied ammonia is mixed by the mixer 29. In this embodiment, if ammonia water generated by the abatement device 6 is stored, this ammonia water is supplied as the reducing agent. If this ammonia water is insufficient, it is preferable to add liquefied ammonia or supply urea water. By prioritizing the treatment of ammonia water, the consumption of urea water can be reduced. Furthermore, it is possible to reduce the capacity of the urea water tank.

[0078] The density of the ammonia water mixed with the additional liquefied ammonia is measured by the second flow rate / density meter 10b. That is, the amount of liquefied ammonia to be added is calculated from the density of the ammonia water in the ammonia water transport pipe 18 measured by the flow rate / density meter 10b, the density of the ammonia water in the ammonia water transport pipe 18 after the addition is measured by the second flow rate / density meter 10b and converted into an ammonia water concentration, and the third on-off valve 12 is operated in accordance with this ammonia water concentration.

[0079] In this embodiment, when urea water is supplied in a sea area subject to Tier 3 regulations, the amount of urea water supplied is adjusted in the same manner as in the first embodiment (FIG. 2).

[0080] (2) Supply in Tier 2 Regulation (Tier 2) Sea Areas In this embodiment, in Tier 2 regulation (Tier 2) sea areas, only ammonia water is supplied, and the adjustment of the supply amount of ammonia water is the same as in the first embodiment ( FIG. 2 ). In this case, since liquefied ammonia is not added, the adjustment of the supply amount of ammonia water to the selective reduction catalyst unit 17 can be performed by calculating the concentration of ammonia water from the density of ammonia water measured by the flow rate / density meter 10 and adjusting the output of the ammonia water pump 18 a in accordance with this concentration, as in the first embodiment ( FIG. 2 ).

[0081] [Structure of Nozzle and Selective Reduction Catalyst Unit (1)] FIG. 4 is a schematic cross-sectional view showing a first structure of the nozzle and selective reduction catalyst unit applied to the ammonia gas treatment apparatus of the first embodiment (FIG. 2) and the second embodiment (FIG. 3).

[0082] As shown in FIG. 4 , exhaust gas from the engine 3 is introduced into the selective catalytic reduction unit 17 from the combustion chamber 3 a of the engine 3 via an exhaust receiver 27. The exhaust gas that has passed through the exhaust receiver 27 rotates the turbine of a turbocharger 52 and is exhausted into the atmosphere. Intake air compressed by the turbine of the turbocharger 52 is supplied to the combustion chamber 3 a. Two-stage selective catalytic reduction catalysts (SCR) 17 a, 17 b are arranged inside the selective catalytic reduction unit 17, one on the upstream side (inlet side) and the other on the downstream side (exhaust side). By providing multiple stages of selective catalytic reduction, it becomes easy to separate the roles of each catalyst, and a sufficient reaction area can be ensured without increasing the size of the selective catalytic reduction unit 17. Note that the selective catalytic reduction does not have to be multiple stages.

[0083] The nozzle 13 that supplies urea water or ammonia water together with air into the selective reduction catalyst unit 17 is a two-fluid nozzle that has two flow paths: a flow path that is connected to the air supply source 25 and that supplies air, and a flow path that is connected to the urea water or ammonia water transport pipe 28 and that sprays urea water or ammonia water.

[0084] This nozzle 13 supplies air from upstream of the upstream selective reduction catalyst 17a via a flow path for supplying air, and also sprays urea water or ammonia water from upstream of the upstream selective reduction catalyst 17a via a flow path for spraying urea water or ammonia water.

[0085] This nozzle 13 can spray both ammonia water and urea water from the central axis of the selective catalytic reduction unit 17, allowing for uniform diffusion. Furthermore, this nozzle 13 only requires one nozzle (one port) to be disposed within the selective catalytic reduction unit 17, making the structure simple.

[0086] 5 is a block diagram showing the configuration of an ammonia gas treatment apparatus according to a third embodiment of the present invention. An ammonia gas treatment method according to the third embodiment of the present invention is carried out in this ammonia gas treatment apparatus.

[0087] As shown in FIG. 5, in this embodiment, the urea water transport pipe 15 and the ammonia water transport pipe 18 in the first embodiment (FIG. 2) are not joined together, but are connected to the nozzle 13 independently.

[0088] In this ammonia gas treatment device, the urea water flow rate control valve 19 is operated in accordance with the measurement results of the urea water flow meter 20 and the flow / density meter 10. This is to make the sum of the molar equivalent of the urea water and the molar equivalent of the ammonia water supplied equal to the molar equivalent when only urea water is supplied. The molar equivalent when only urea water is supplied is a molar equivalent necessary and sufficient for denitration treatment in the selective reduction catalyst unit 17.

[0089] In this embodiment, the pressure gauge 24 measures the pressure inside the urea water transport pipe 15. The pressure inside the ammonia water transport pipe 18 is measured by a PT 23 (hereinafter referred to as an "ammonia water pressure gauge 23").

[0090] The air supply source 25 supplies the air to be supplied into the selective catalytic reduction unit 17 together with the urea water to the urea water transport pipe 15, and supplies the air to be supplied into the selective catalytic reduction unit 17 together with the ammonia water to the ammonia water transport pipe 18. The air supply source 25 may supply air directly to the nozzle 13 through a single pipe, instead of through the urea water transport pipe 15 and the ammonia water transport pipe 18. The same applies to a fourth embodiment (FIG. 6) described later.

[0091] In this embodiment, urea water and ammonia water can be supplied and sprayed simultaneously. In this embodiment, in water areas subject to Tier 3 regulations on exhaust gas from marine diesel engines, urea water and / or ammonia water is supplied to the selective catalytic reduction unit 17 to perform denitration treatment, and in water areas subject to Tier 2 regulations, ammonia water is supplied to the selective catalytic reduction unit 17 to perform ammonia water detoxification treatment. In the ammonia water detoxification treatment, it is not necessary to denitrify all of the nitrogen oxides (NOx) in the engine exhaust gas.

[0092] When ammonia water is supplied to the selective reduction catalyst unit 17, the concentration of the ammonia water is calculated from the density of the ammonia water measured by the flow rate / density meter 10, and the output of the ammonia water pump 18a is adjusted in accordance with this concentration, thereby making it possible to control the concentration of the ammonia water supplied to the selective reduction catalyst unit 17, and making it possible for the entire amount of ammonia water supplied to be detoxified in the selective reduction catalyst unit 17.

[0093] The supply of urea water and / or ammonia water to this ammonia gas treatment device is carried out, for example, as follows.

[0094] (1) Supply in Tier 3 Sea Areas In the ammonia gas treatment device of this embodiment, denitrification treatment can be performed in Tier 3 sea areas by simultaneously supplying urea water and ammonia water. In this embodiment, if ammonia water generated by the detoxification device 6 is stored, this ammonia water is preferably supplied as the reducing agent, and if this ammonia water is insufficient, urea water is preferably supplied simultaneously. By prioritizing the treatment of ammonia water, the amount of urea water consumed can be reduced. In addition, the capacity of the urea water tank can be reduced.

[0095] In this embodiment, the urea water pump 15a and the ammonia water pump 18a are started to simultaneously supply urea water and ammonia water. The flow rates of the urea water and ammonia water are adjusted so that the total supply amount of urea water and ammonia water supplied to the selective reduction catalyst unit 17 is a supply amount converted from the total molar equivalent of the urea water and ammonia water that is necessary and sufficient for the denitration treatment in the selective reduction catalyst unit 17. The total molar equivalent of urea water and ammonia water that is necessary and sufficient for the denitration treatment in the selective reduction catalyst unit 17 is equal to the molar equivalent of urea water that should be supplied when only urea water is supplied to the selective reduction catalyst unit 17.

[0096] In addition, with regard to the total supply amount of urea water and ammonia water, the supply amount of either urea water or ammonia water may be 0 (not supplied). When urea water and ammonia water are not sprayed simultaneously, the supply amount of either urea water or ammonia water is set to 0 (not supplied).

[0097] When the supply amount of ammonia water is set to 0 (no supply), the ammonia water pump 18a is stopped and only urea water is supplied, in this case, the adjustment of the supply amount of urea water is the same as in the first embodiment (FIG. 2).When the supply amount of urea water is set to 0 (no supply), the urea water pump 15a is stopped and only ammonia water is supplied, in this case, the adjustment of the supply amount of ammonia water is the same as in the first embodiment (FIG. 2).

[0098] (2) Supply in Tier 2 Regulation Sea Areas In this embodiment, only ammonia water is supplied in Tier 2 regulation sea areas, and the amount of ammonia water supplied is adjusted in the same manner as in the first embodiment (FIG. 2).

[0099] 6 is a block diagram showing the configuration of an ammonia gas treatment apparatus according to a fourth embodiment of the present invention. An ammonia gas treatment method according to the fourth embodiment of the present invention is carried out in this ammonia gas treatment apparatus.

[0100] As shown in Fig. 6, this embodiment is the third embodiment (Fig. 5) except that, similarly to the second embodiment (Fig. 3), a mixer 29 for mixing additional liquefied ammonia with the ammonia water sent from the abatement device 6 and a second flow rate / density meter 10b are provided. The second flow rate / density meter 10b is a Coriolis flow meter, and can measure the flow rate and density of the ammonia water after the additional liquefied ammonia has been mixed.

[0101] In this ammonia gas treatment device, liquefied ammonia is supplied from the fuel supply device 2 to a position downstream of the third on-off valve 12 of the ammonia water transport pipe 18 and merges with the ammonia water. The liquefied ammonia is supplied from the fuel supply device 2 to the ammonia water transport pipe 18 via a liquefied ammonia back pressure valve (regulator) 31 and a liquefied ammonia flow meter 32.

[0102] The ammonia water mixed with the liquefied ammonia is sent to the mixer 29, and the liquefied ammonia and the ammonia water are mixed to produce ammonia water. Cooling water that cools the ammonia water transport pipe 18 from the outside is supplied to the mixer 29. The ammonia water that has passed through the mixer 29 is sent to the nozzle 13 via a check valve 30. A check valve 33 is provided downstream of the urea water flow meter 20 provided in the urea water transport pipe 15.

[0103] In this embodiment, it is possible to simultaneously spray urea water and ammonia water. In this embodiment, in water areas subject to Tier 3 regulations on exhaust gas from marine diesel engines, urea water and / or ammonia water are supplied to the selective catalytic reduction unit 17 to perform denitration treatment, and in water areas subject to Tier 2 regulations, ammonia water is supplied to the selective catalytic reduction unit 17 to perform detoxification or denitration of ammonia water.

[0104] When the concentration and / or flow rate of ammonia water is insufficient during denitration treatment, the pressure of liquefied ammonia discharge from fuel supply device 2 is increased, and liquefied ammonia is mixed with ammonia water via liquefied ammonia back pressure valve 31 and liquefied ammonia flow meter 32. The amount of liquefied ammonia supplied is adjusted by adjusting the pressure of liquefied ammonia discharge from fuel supply device 2 and the flow rate through liquefied ammonia back pressure valve 31 while measuring the flow rate of liquefied ammonia with liquefied ammonia flow meter 32 and the flow rate and density of ammonia water with flow / density meter 10. By mixing liquefied ammonia, the ammonia water supplied to selective reduction catalyst unit 17 has a concentration sufficient for denitration treatment. In this case, the amount of urea water consumed can be reduced.

[0105] The supply of urea water and / or ammonia water to this ammonia gas treatment device is carried out, for example, as follows.

[0106] (1) Supply in Tier 3 Sea Areas In this embodiment, when urea water and ammonia water are simultaneously supplied in Tier 3 sea areas, the adjustment of the supply amounts of urea water and ammonia water is the same as in the third embodiment ( FIG. 5 ). However, the adjustment of the supply amount of ammonia water to the selective reduction catalyst unit 17 is performed by calculating the concentration of ammonia water from the density of ammonia water measured by a second flow rate / density meter 10 b instead of the flow rate / density meter 10, and adjusting the output of the ammonia water pump 18 a according to this concentration. This is because liquefied ammonia may be added.

[0107] In this embodiment, if ammonia water generated by the detoxification device 6 is stored, this ammonia water is preferably supplied as the reducing agent, and if this ammonia water is insufficient, liquefied ammonia is added and / or urea water is simultaneously supplied. By prioritizing the treatment of ammonia water, the amount of urea water consumed can be reduced. Also, the capacity of the urea water tank can be reduced.

[0108] In this embodiment, when only urea water is supplied in a sea area subject to Tier 3 regulations, the adjustment of the supply amount of urea water is the same as in the first embodiment (FIG. 2). In this embodiment, when only ammonia water is supplied in a sea area subject to Tier 3 regulations, the adjustment of the supply amount of ammonia water is the same as in the second embodiment (FIG. 3). This is because liquefied ammonia may be added.

[0109] (2) Supply in Tier 2 Regulation (Tier 2) Sea Areas In this embodiment, in Tier 2 regulation (Tier 2) sea areas, only ammonia water is supplied, and the adjustment of the supply amount of ammonia water is the same as in the second embodiment ( FIG. 3 ). In this case, since liquefied ammonia is not added, the adjustment of the supply amount of ammonia water to the selective reduction catalyst unit 17 can be performed by calculating the concentration of ammonia water from the density of ammonia water measured by the flow rate / density meter 10 and adjusting the output of the ammonia water pump 18 a in accordance with this concentration, as in the first embodiment ( FIG. 2 ).

[0110] [Structure (2) of Nozzle and Selective Reduction Catalyst Unit] FIG. 7 is a schematic cross-sectional view showing a second structure of the nozzle and selective reduction catalyst unit applied to the ammonia gas treatment apparatus of the third embodiment (FIG. 5) and the fourth embodiment (FIG. 6).

[0111] 7, the nozzle 13 may be a three-fluid nozzle having three flow paths: a flow path connected to the air supply source 25 for supplying air, a flow path connected to the ammonia water transport pipe 18 for supplying ammonia water, and a flow path connected to the urea water transport pipe 15 for supplying urea water. In this structural example, the flow path for supplying air is used in common for diffusing ammonia water and urea water.

[0112] This nozzle 13 supplies diffusion air from upstream of the upstream selective reduction catalyst 17a via an air flow path, sprays ammonia water from upstream of the upstream selective reduction catalyst 17a via an ammonia water flow path, and sprays urea water from upstream of the upstream selective reduction catalyst 17a via a urea water flow path.

[0113] This nozzle 13 can spray both ammonia water and urea water from the central axis of the selective catalytic reduction unit 17, allowing for uniform diffusion. Furthermore, this nozzle 13 only requires one nozzle (one port) to be disposed within the selective catalytic reduction unit 17, making the structure simple.

[0114] In this nozzle 13, the urea water and the ammonia water are sprayed through their own dedicated flow paths, so that it is possible to accommodate a large difference between the amount of ammonia water to be sprayed and the amount of urea water to be sprayed.

[0115] The selective catalytic reduction unit 17 using this nozzle 13 sprays urea water and / or ammonia water in water areas subject to Tier 3 regulations of exhaust gas regulations for marine diesel engines, and sprays ammonia water in water areas subject to Tier 2 regulations. When spraying ammonia water in water areas subject to Tier 3 regulations, it is necessary to manage the concentration of the ammonia water in order to ensure a necessary and sufficient amount of ammonia components for denitration treatment.

[0116] In this nozzle 13, the flow path for urea water can be a high flow path, and the flow path for ammonia water can be a low flow path. The flow rate of air is adjusted by a control valve with a flow meter in response to a signal indicating whether the mode is for spraying urea water or ammonia water. By using this nozzle 13, it is possible to execute a low flow mode that only treats ammonia water in Tier 2 regulation areas. In this case, urea water and ammonia water are not sprayed simultaneously.

[0117] In the structural example of the nozzle 13 described above, the flow path for supplying air is shared between the diffusion of ammonia water and the diffusion of urea water, but this is not limited to this, and a flow path for supplying air for diffusing ammonia water and a flow path for supplying air for diffusing urea water may be provided separately.

[0118] That is, the nozzle 13 may be a three-fluid nozzle having four flow paths: a flow path connected to the urea water transport pipe 15 for spraying urea water, a flow path connected to the ammonia water transport pipe 18 for spraying ammonia water, a flow path connected to the air supply source 25 and having an opening for supplying air for diffusing the urea water, and a flow path connected to the air supply source 25 and having an opening for supplying air for diffusing the ammonia water.

[0119] The nozzle 13 supplies the ammonia water diffusion air and the ammonia water from upstream of the upstream selective reduction catalyst 17a via a flow path for the ammonia water diffusion air and a flow path for the ammonia water, and sprays the urea water diffusion air and the urea water from upstream of the upstream selective reduction catalyst 17a via a flow path for the urea water diffusion air and a flow path for the urea water.

[0120] By using this nozzle 13, the supply amounts of air for diffusing ammonia water and ammonia water, and the supply amounts of air for diffusing urea water and urea water can be changed according to the load of the engine 3.

[0121] [Structure of Nozzle and Selective Reduction Catalyst Unit (3)] FIG. 8 is a schematic cross-sectional view showing a third structure of the nozzle and selective reduction catalyst unit applied to the ammonia gas treatment apparatus of the third embodiment (FIG. 5) and the fourth embodiment (FIG. 6).

[0122] 8, the nozzle may be composed of a first nozzle 13a and a second nozzle 13b. The first nozzle 13a is a two-fluid nozzle having two flow paths: a flow path connected to the air supply source 25 for supplying air, and a flow path connected to the urea water transport pipe 15 for spraying urea water. The second nozzle 13b is a two-fluid nozzle having two flow paths: a flow path connected to the air supply source 25 for supplying air, and a flow path connected to the ammonia water transport pipe 18 for spraying ammonia water.

[0123] The first nozzle 13a supplies air via an air flow path from upstream of the upstream selective reduction catalyst 17a, and sprays urea water via a urea water flow path from upstream of the upstream selective reduction catalyst 17a. The second nozzle 13b supplies air via an air flow path from upstream of the upstream selective reduction catalyst 17a, and sprays ammonia water via an ammonia water flow path from upstream of the upstream selective reduction catalyst 17a.

[0124] The first nozzle 13 a and the second nozzle 13 b are both arranged near the central axis of the selective reduction catalyst unit 17, but the central axis may be the Z axis, and the nozzles may be arranged such that the X-axis direction and the Z-axis direction are the same and only the Y-axis direction is different, or the nozzles may be arranged such that the Y-axis direction and the Z-axis direction are the same and only the X-axis direction is different.

[0125] When these first nozzle 13 a and second nozzle 13 b are used, the urea water and the ammonia water are sprayed from the dedicated first nozzle 13 a and second nozzle 13 b, respectively, so that the urea water and the ammonia water can be sprayed simultaneously, and it is possible to deal with a large difference between the amount of ammonia water to be sprayed and the amount of urea water to be sprayed. The amount of urea water to be sprayed and the amount of ammonia water to be sprayed can be adjusted according to the operating state of the engine 3.

[0126] The selective catalytic reduction unit 17 using this nozzle 13 sprays urea water and / or ammonia water in water areas subject to Tier 3 regulations of exhaust gas regulations for marine diesel engines, and sprays ammonia water in water areas subject to Tier 2 regulations. When spraying ammonia water in water areas subject to Tier 3 regulations, it is necessary to manage the concentration of the ammonia water in order to ensure a necessary and sufficient amount of ammonia components for denitration treatment.

[0127] [Structure (4) of Nozzle and Selective Reduction Catalyst Unit] FIG. 9 is a schematic cross-sectional view showing a fourth structure of the nozzle and selective reduction catalyst unit applied to the ammonia gas treatment apparatus of the third embodiment (FIG. 5) and the fourth embodiment (FIG. 6).

[0128] As shown in FIG. 9, the nozzle may be made up of a first nozzle 13 a and a second nozzle 13 b , and the second nozzle 13 b may be disposed within the exhaust receiver 27 .

[0129] The first nozzle 13a is a two-fluid nozzle having two flow paths: a flow path connected to the air supply source 25 for supplying air, and a flow path connected to the urea water transport pipe 15 for spraying urea water. The second nozzle 13b is a two-fluid nozzle having two flow paths: a flow path connected to the air supply source 25 for supplying air, and a flow path connected to the ammonia water transport pipe 18 for spraying ammonia water.

[0130] The first nozzle 13a supplies air via an air flow path from upstream of the upstream selective reduction catalyst 17a, and sprays urea water via a urea water flow path from upstream of the upstream selective reduction catalyst 17a within the selective reduction catalyst unit 17. The second nozzle 13b supplies air via an air flow path from upstream of the upstream selective reduction catalyst 17a, and sprays ammonia water into the exhaust receiver 27 via an ammonia water flow path.

[0131] In the first nozzle 13a and the second nozzle 13b, both the ammonia water and the urea water can be sprayed from the central axis of the selective reduction catalyst unit 17, and therefore can be dispersed uniformly.

[0132] When these first nozzle 13 a and second nozzle 13 b are used, the urea water and the ammonia water are sprayed from the dedicated first nozzle 13 a and second nozzle 13 b, respectively, so that the urea water and the ammonia water can be sprayed simultaneously, and it is possible to deal with a large difference between the amount of urea water to be sprayed and the amount of ammonia water to be sprayed. The amount of urea water to be sprayed and the amount of ammonia water to be sprayed can be adjusted according to the operating state of the engine 3.

[0133] When the first nozzle 13 a and the second nozzle 13 b are used, the outlet temperature of the exhaust receiver 27 is higher than the inlet temperature of the selective catalytic reduction unit 17, so it is possible to suppress a decrease in the temperature of the exhaust gas even if the concentration of the ammonia water is low and the spray amount is large. The first nozzle 13 a and the second nozzle 13 b are suitable when the spray amount of the ammonia water is about 1 / 10 or less of the spray amount of the urea water.

[0134] The selective catalytic reduction unit 17 using this nozzle 13 sprays urea water and / or ammonia water in water areas subject to Tier 3 regulations of exhaust gas regulations for marine diesel engines, and sprays ammonia water in water areas subject to Tier 2 regulations. When spraying ammonia water in water areas subject to Tier 3 regulations, it is necessary to manage the concentration of the ammonia water in order to ensure a necessary and sufficient amount of ammonia components for denitration treatment.

[0135] The first nozzle 13a that sprays urea water may also be disposed in the exhaust receiver 27, similar to the second nozzle 13b.

[0136] [Structure (5) of Nozzle and Selective Reduction Catalyst Unit] FIG. 10 is a schematic cross-sectional view showing a fifth structure of the nozzle and selective reduction catalyst unit that is applied to the ammonia gas treatment apparatus of the third embodiment (FIG. 5) and the fourth embodiment (FIG. 6).

[0137] As shown in FIG. 10 , the nozzle may be composed of a first nozzle 13 a and a second nozzle 13 b, and the second nozzle 13 b may be disposed upstream of an ammonia slip catalyst (ASC) 17 c that is installed in place of the downstream selective reduction catalyst 17 b.

[0138] The first nozzle 13a is a two-fluid nozzle having two flow paths: a flow path connected to the air supply source 25 for supplying air, and a flow path connected to the urea water transport pipe 15 for spraying urea water. The second nozzle 13b is a two-fluid nozzle having two flow paths: a flow path connected to the air supply source 25 for supplying air, and a flow path connected to the ammonia water transport pipe 18 for spraying ammonia water.

[0139] The first nozzle 13a supplies air via an air flow path from upstream of the upstream selective reduction catalyst 17a, and sprays urea water via a urea water flow path from upstream of the upstream selective reduction catalyst 17a within the selective reduction catalyst unit 17. The second nozzle 13b supplies air via an air flow path from upstream of the upstream selective reduction catalyst 17a, and sprays ammonia water via an ammonia water flow path from downstream of the upstream selective reduction catalyst 17a within the selective reduction catalyst unit 17, upstream of an ammonia slip catalyst (ASC) 17c installed in place of the downstream selective reduction catalyst 17b.

[0140] In the first nozzle 13a and the second nozzle 13b, both the ammonia water and the urea water can be sprayed from the central axis of the selective reduction catalyst unit 17, and therefore can be dispersed uniformly.

[0141] When these first nozzle 13 a and second nozzle 13 b are used, the urea water and the ammonia water are sprayed from the dedicated first nozzle 13 a and second nozzle 13 b, respectively, so that the urea water and the ammonia water can be sprayed simultaneously, and it is possible to deal with a large difference between the amount of ammonia water to be sprayed and the amount of urea water to be sprayed. The amount of urea water to be sprayed and the amount of ammonia water to be sprayed can be adjusted according to the operating state of the engine 3.

[0142] When the first nozzle 13 a and the second nozzle 13 b are used, the nitrogen oxide reduction treatment is completed only by the upstream selective reduction catalyst 17 a, and the downstream ammonia slip catalyst is specialized for treating the ammonia water. The first nozzle 13 a and the second nozzle 13 b are suitable when the amount of ammonia water sprayed is about 1 / 10 or less of the amount of urea water sprayed.

[0143] In this nozzle, the second nozzle 13b may also be configured to spray ammonia water from upstream of the upstream selective reduction catalyst 17a in the selective reduction catalyst unit 17. In this case, if excess ammonia gas is produced during the denitration process in the selective reduction catalyst 17a, this ammonia gas is rendered harmless by the downstream ammonia slip catalyst.

[0144] In the selective catalytic reduction unit 17 using this nozzle 13, urea water and ammonia water are sprayed in water areas subject to Tier 3 regulations of exhaust gas restrictions for marine diesel engines, and ammonia water is sprayed in water areas subject to Tier 2 regulations (Tier 2). In the selective catalytic reduction unit 17 using this nozzle 13, ammonia water is not involved in the denitrification treatment, so concentration management is not required, but concentration management may be performed to confirm that the amount of the ammonia component is not more than the processing capacity of the ammonia slip catalyst (ASC) 17c.

[0145] As described above, in the ammonia gas treatment device and treatment method, in waters subject to Tier 3 regulations on marine diesel engine exhaust gases, the selective catalytic reduction unit 17 reliably performs denitration treatment using urea water, thereby satisfying the regulations and enabling onboard treatment of ammonia gas generated on board the ship. The ammonia water is consumed in the detoxification treatment, eliminating the need for an additional ammonia water supply tank, thereby reducing the capacity of the ammonia water tank. Furthermore, in an embodiment in which ammonia water produced by the denitrification device is used for denitration treatment, denitration treatment using ammonia water can be performed in waters subject to Tier 2 regulations, where denitration is not necessarily required, thereby providing a clean ship that produces clean exhaust gas with reduced nitrogen oxides in all waters.

[0146] REFERENCE SIGNS LIST 1 Liquefied ammonia tank 1a Suction pump 2 Fuel supply device 2a Ammonia discharge valve 3 Engine 3a Combustion chamber 4 Fuel piping 4a Gas-liquid separator 5 Purge gas discharge valve 6 Abatement device 7 Ammonia water tank 7a Liquid level gauge 8 Urea water tank 9 Second on-off valve 10 Flow rate / density meter (Coriolis flow meter) 10b Second flow rate / density meter (Coriolis flow meter) 11 Ammonia water flow meter 12 Third on-off valve 13 Nozzle 13a First nozzle 13b Second nozzle 14 Ammonia water circulation valve (back pressure valve) 15 Urea water transport pipe 15a Urea water pump 16 First on-off valve 17 Selective catalytic reduction unit 17a Selective catalytic reduction (SCR) 17b Selective catalytic reduction (SCR) 17c Ammonia slip catalyst (ASC) 18 Ammonia water transport pipe 18a Ammonia water pump 19 Urea water flow rate adjustment valve 20 Urea water flow meter 21 Urea water circulation valve (back pressure valve) 22 Fresh water tank 22a Water supply pump 23 Ammonia water pressure gauge 24 Pressure gauge 25 Air supply source 26 Thermometer 27 Exhaust gas receiver 28 Urea water or ammonia water transport pipe 29 Mixer 30 Check valve 31 Liquefied ammonia back pressure valve 32 Liquefied ammonia flow meter 33 Check valve 50 Purge gas supply valve 51 Nitrogen gas supply device 52 Turbocharger

Claims

1. An ammonia gas treatment device for a ship carrying liquefied ammonia as fuel for cargo or the ship's engine and equipped with a selective reduction catalyst unit, wherein exhaust gas from the ship's engine is introduced into the selective reduction catalyst unit, a urea solution as a reducing agent can be supplied, and a selective reduction catalyst is disposed in the selective reduction catalyst unit for denitrifying the exhaust gas, and the selective reduction catalyst is further equipped with a detoxification device for dissolving ammonia gas and / or ammonia gas vaporized from liquefied ammonia remaining in the fuel supply line of the ship's engine, or ammonia gas volatilized from the cargo, in fresh water to produce ammonia water, and the ammonia water produced by the detoxification device is supplied to the selective reduction catalyst unit to detoxify the ammonia water.

2. The ammonia gas treatment device according to claim 1, characterized in that a supply path for the ammonia water to the selective reduction catalyst unit reaches the selective reduction catalyst unit independently of a supply path for the urea water to the selective reduction catalyst unit, the urea water and the ammonia water can be simultaneously supplied to the selective reduction catalyst unit through a nozzle, the nozzle being a three-fluid nozzle having a flow path connected to an air supply source and supplying air for diffusing the urea water and / or the ammonia water, a flow path connected to the urea water supply path and spraying the urea water, and a flow path connected to the ammonia water supply path and spraying the ammonia water, and is disposed upstream within the selective reduction catalyst unit.

3. The ammonia gas treatment device according to claim 1, characterized in that a supply path for the ammonia water to the selective reduction catalyst unit leads to the selective reduction catalyst unit independently of a supply path for the urea water to the selective reduction catalyst unit, the urea water and the ammonia water can be simultaneously supplied to the selective reduction catalyst unit through a nozzle, the nozzle being comprised of a first nozzle and a second nozzle, the first nozzle being a two-fluid nozzle having two flow paths, a flow path connected to the air supply source and supplying air, and a flow path connected to the urea water supply path and spraying the urea water, and is disposed upstream within the selective reduction catalyst unit, and the second nozzle being a two-fluid nozzle having two flow paths, a flow path connected to the air supply source and supplying air, and a flow path connected to the ammonia water supply path and spraying the ammonia water, and is disposed upstream within the selective reduction catalyst unit.

4. The ammonia gas treatment device according to claim 1, wherein a supply path for the ammonia water to the selective reduction catalyst unit leads to the selective reduction catalyst unit independently of a supply path for the urea water to the selective reduction catalyst unit, the urea water and the ammonia water can be simultaneously supplied to the selective reduction catalyst unit through a nozzle, the nozzle comprising a first nozzle and a second nozzle, the first nozzle being a two-fluid nozzle having two flow paths, a flow path connected to the air supply source for supplying air and a flow path connected to the urea water supply path for spraying the urea water, and is disposed upstream within the selective reduction catalyst unit, the second nozzle being a two-fluid nozzle having two flow paths, a flow path connected to the air supply source for supplying air and a flow path connected to the ammonia water supply path for spraying the ammonia water, and is disposed within an exhaust receiver through which the exhaust gas passes prior to the selective reduction catalyst unit, and the air and the ammonia water are supplied into the selective reduction catalyst unit through this exhaust receiver.

5. The ammonia gas treatment device according to claim 1, characterized in that a supply path for the ammonia water to the selective reduction catalyst unit merges with a supply path for the urea water to the selective reduction catalyst unit before the selective reduction catalyst unit is reached, and either the urea water or the ammonia water is supplied to the selective reduction catalyst unit through a nozzle, and the nozzle is a two-fluid nozzle having two flow paths: a flow path connected to an air supply source for supplying air, and a flow path connected by the merger of the urea water supply path and the ammonia water supply path for spraying the urea water or the ammonia water, and is disposed upstream within the selective reduction catalyst unit.

6. The ammonia gas treatment device according to any one of claims 1 to 4, further comprising: a meter for measuring a density of the ammonia water; simultaneously supplying the urea water and the ammonia water to the selective reduction catalyst unit; converting the density of the ammonia water measured by the meter for measuring the density of the ammonia water into a concentration of ammonia water and calculating from this concentration a molar equivalent of the ammonia water to be supplied to the selective reduction catalyst unit; calculating from the known concentration of the urea water a molar equivalent of the urea water to be supplied to the selective reduction catalyst unit; adding together the molar equivalent of the ammonia water and the molar equivalent of the urea water supplied to the selective reduction catalyst unit; and adjusting flow rates of the urea water and the ammonia water in accordance with the combined molar equivalent, thereby performing a denitrification treatment of the exhaust gas as the detoxification treatment.

7. The ammonia gas treatment device according to any one of claims 1 to 5, characterized in that a supply path for the ammonia water to the selective reduction catalyst unit is joined with liquefied ammonia supplied from a fuel supply device of the ship, the ammonia water and the liquefied ammonia are mixed to become ammonia water and the ammonia water is supplied to the selective reduction catalyst unit, the device further comprising an instrument for measuring a density of the ammonia water obtained by mixing the ammonia water and the liquefied ammonia, a molar equivalent of the ammonia water to be supplied to the selective reduction catalyst unit is calculated from the density of the ammonia water measured by the instrument for measuring the density of the ammonia water, and a flow rate of the ammonia water is adjusted according to the calculated molar equivalent, thereby performing a denitrification treatment of the exhaust gas as the detoxification treatment.

8. The ammonia gas treatment device according to any one of claims 1 to 5, further comprising an instrument for measuring a leak ammonia concentration in the exhaust gas, measuring an exhaust gas flow rate of the engine, and calculating an amount of leak ammonia from the measured exhaust gas flow rate and the leak ammonia concentration, or from an exhaust gas flow rate calculated from load information from an output of the engine and the leak ammonia concentration, and adjusting a flow rate of the urea water or the ammonia water so that a sum of an amount of ammonia supplied into the selective reduction catalyst unit by the urea water and / or the ammonia water and the amount of leak ammonia becomes an amount of ammonia treated in the selective reduction catalyst unit, thereby performing a denitrification treatment of the exhaust gas as the detoxification treatment.

9. The ammonia gas treatment device according to any one of claims 1 to 5, characterized in that an ammonia slip catalyst is disposed within the selective reduction catalyst unit, and the ammonia water supplied to the selective reduction catalyst unit is detoxified by the ammonia slip catalyst.

10. A method for treating ammonia gas in a ship carrying liquefied ammonia as fuel for cargo or the ship's engine and equipped with a selective reduction catalyst unit, comprising: a selective reduction catalyst into which exhaust gas from the ship's engine is introduced and into which a reducing agent, urea water, can be supplied, and which performs a denitrification treatment of the exhaust gas; ammonia gas produced by vaporization of liquefied ammonia remaining in the fuel supply line of the ship's engine and / or ammonia gas, or ammonia gas volatilized from the cargo, is dissolved in fresh water by a detoxification device to produce ammonia water; and the ammonia water produced by the detoxification device is supplied to the selective reduction catalyst unit to detoxify the ammonia water.

11. The method for treating ammonia gas according to claim 10, further comprising the steps of: simultaneously supplying the urea water and the ammonia water to the selective reduction catalyst unit; measuring a density of the ammonia water; converting the measured density of the ammonia water into a concentration of ammonia water and calculating, from this concentration, a molar equivalent of the ammonia water to be supplied to the selective reduction catalyst unit; calculating, from the known concentration of the urea water, a molar equivalent of the urea water to be supplied to the selective reduction catalyst unit; adding together the molar equivalent of the ammonia water and the molar equivalent of the urea water to be supplied to the selective reduction catalyst unit; adjusting flow rates of the urea water and the ammonia water in accordance with the combined molar equivalent; and performing a denitrification treatment of the exhaust gas as the detoxification treatment.

12. The method for treating ammonia gas according to claim 10, further comprising: merging liquefied ammonia supplied from a fuel supply device of the ship into a supply path for the ammonia water to the selective reduction catalyst unit, mixing the ammonia water with the liquefied ammonia to prepare ammonia water, and supplying the ammonia water to the selective reduction catalyst unit; measuring a density of the ammonia water obtained by mixing the ammonia water with the liquefied ammonia; calculating a molar equivalent of the ammonia water to be supplied to the selective reduction catalyst unit from the measured density of the ammonia water; adjusting a flow rate of the ammonia water in accordance with the calculated molar equivalent; and performing a denitrification treatment of the exhaust gas as the detoxification treatment.

13. The method for treating ammonia gas according to claim 10, further comprising the steps of: providing an instrument for measuring a leak ammonia concentration in the exhaust gas; measuring an exhaust gas flow rate of the engine; and calculating an amount of leak ammonia from the measured exhaust gas flow rate and the leak ammonia concentration, or from an exhaust gas flow rate calculated from load information from an output of the engine and the leak ammonia concentration; and adjusting a flow rate of the urea water or the ammonia water so that the sum of the amount of ammonia supplied into the selective reduction catalyst unit by the urea water and / or the ammonia water and the amount of leak ammonia becomes the amount of ammonia treated in the selective reduction catalyst unit, thereby performing a denitrification treatment of the exhaust gas as the detoxification treatment.

14. The method for treating ammonia gas according to claim 10, further comprising providing an ammonia slip catalyst within the selective reduction catalyst unit, and using the ammonia slip catalyst to detoxify the ammonia water supplied to the selective reduction catalyst unit.

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