Engine exhaust gas treatment device and engine exhaust gas treatment method

Abstract

To provide a treatment device for discharge gas of an engine with a simple device configuration, capable of safely supplying a reductant such as an ammonia aqueous solution or alcohol to a discharge gas purification device for purifying NOx (nitrogen oxide) contained in discharge gas of an engine.SOLUTION: A treatment device for discharge gas of an engine comprises a selective reduction catalyst unit 1 into which exhaust gas of an engine 101 of a ship is introduced, to which a reductant R is supplied, and which denitrifies the exhaust gas of the engine. The reductant R passes through an inner pipe 3 of a double pipe 2 and is supplied to the selective reduction catalyst unit 1 via a nozzle 4, inert gas or atmospheric air G flows through an outer pipe 5 of the double pipe 2 in the same direction as the reductant R, and the inert gas or atmospheric air G is supplied to the selective reduction catalyst unit 1 as dispersion gas for dispersing the reductant R.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an engine exhaust gas treatment device and an engine exhaust gas treatment method for ships carrying liquefied ammonia, alcohol, etc., as cargo or engine fuel. More specifically, the present invention relates to an engine exhaust gas treatment device and an engine exhaust gas treatment method that can safely supply reducing agents such as aqueous ammonia solution, methanol, ethanol, propanol, and other alcohols to an exhaust gas purification device that purifies NOx (nitrogen oxides) contained in engine exhaust gas, and has a simple device configuration. [Background technology]

[0002] Due to the depletion of fossil fuels and global warming, fuels with low CO2 emissions, such as liquefied ammonia, methanol, ethanol, and propanol, are attracting attention as marine fuels. On the other hand, SCR (Selective Reduction) systems are known as exhaust gas purification devices for purifying NOx (nitrogen oxides) contained in exhaust gases emitted from engines.

[0003] Liquid ammonia and alcohol can be used not only as fuels but also as reducing agents for NOx and other substances. However, as described in Patent Documents 1 and 2 and Non-Patent Document 1, aqueous ammonia solutions and alcohols are toxic and flammable, so sufficient safety measures must be taken when using them as reducing agents.

[0004] Since ammonia and methanol are produced together in a single process, as described in Patent Document 3, they can be used as a mixed fuel on board ships, or liquefied ammonia and methanol can be carried separately on the same ship, or they can be mixed and burned when supplied to the engine. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Patent No. 6154980 [Patent Document 2] Japanese Patent Publication No. 2022-156549 [Patent Document 3] Japanese Patent Publication No. 2022-171351 [Non-patent literature]

[0006] [Non-Patent Document 1] Guidelines for Alternative Fuel Vessels (Version 2.0), Part C-1: Safety Requirements for Ammonia-Fueled Vessels, p. 63 [Overview of the project] [Problems that the invention aims to solve]

[0007] Non-patent document 1 stipulates that when ammonia fuel, an alternative fuel, is routed through piping in safe areas such as the engine room on a ship, the classification society must prevent fuel leakage by using double piping with the inert gas in the outer pipe at a higher pressure than the fuel in the inner pipe, and that the inner pipe should be purged with inert gas when the main fuel valve is closed, and that the outer pipe should be ventilated. Similarly, for alternative fuels such as alcohol and LPG, piping in safe areas should also be double-piped to prevent leakage.

[0008] In Patent Document 1, within a safe zone on board a ship, ventilation gas is supplied to the outer pipe of a double-walled piping system from outside the safe zone using a fan or blower, and the ventilation gas is sent in the opposite direction to the fuel flow, allowing the leaked gas to pass through the safe zone and be discharged to a safe location outside the safe zone. While ventilation gas can be supplied via ducts, as described in Patent Document 1, if the fuel is toxic, the leaked gas must be sent to a detoxification facility via a return pipe before being released into the atmosphere, which complicates the equipment configuration. Furthermore, diluting leaked gas to a safe concentration requires a large amount of ventilation gas, which increases the size and complexity of the equipment configuration.

[0009] Patent document 2 mentions a method of treating leaked gas by installing a scrubber or an ammonia decomposition catalyst, but adding such equipment leads to increased complexity of the system configuration.

[0010] Incidentally, when using ammonia aqueous solutions or alcohol as reducing agents in an SCR system, the piping in the safety zone should be double-piped to prevent leaks. This is because these reducing agents, like fuels, are toxic and flammable, and therefore it is desirable to implement safety standards equivalent to those required for fuel lines. In this double piping system, as described in Non-Patent Document 1 and Patent Document 1, the outer pipe can be ventilated by ventilation gas, which is sent in the opposite direction to the fuel and reducing agent, and is sent to the detoxification equipment via a return pipe.

[0011] In an SCR system, a dispersion gas is necessary to further break down and disperse the reducing agent. Therefore, when using an aqueous ammonia solution or alcohol as a reducing agent in an SCR system, both a dispersion gas to finely disperse the reducing agent and a ventilation gas to ventilate the outer pipe of the double-walled piping are required. The dispersion gas is supplied to the SCR system in the same direction as the reducing agent, while the ventilation gas, as described above, is supplied in the opposite direction to the reducing agent.

[0012] Thus, because both a dispersing gas and a ventilation gas are required, sending them in opposite directions, the system configuration becomes complex due to the need to provide separate supply pipes for both. Furthermore, the ventilation gas must be sent via a return pipe to a detoxification treatment facility, which also contributes to the system configuration complexity. In particular, on ships where space efficiency is paramount, even a single additional pipe or piece of equipment can pose a significant problem.

[0013] Therefore, an object of the present invention is to provide an engine exhaust gas treatment device and an engine exhaust gas treatment method that can safely supply a reducing agent such as an aqueous ammonia solution or alcohol to an exhaust gas purification device that purifies NOx (nitrogen oxides) contained in engine exhaust gas and has a simple device configuration.

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

Means for Solving the Problems

[0015] The above problems are solved by the following inventions. 1. A selective reduction catalyst unit is provided, into which engine exhaust gas of a ship is introduced, a reducing agent is supplied, and a selective reduction catalyst for performing denitrification treatment of the engine exhaust gas is arranged. The reducing agent is supplied to the selective reduction catalyst unit through a nozzle via the inner pipe of a double pipe. An inert gas or air flows through the outer pipe of the double pipe in the same direction as the reducing agent. The inert gas or air is supplied to the selective reduction catalyst unit as a dispersion gas for dispersing the reducing agent. An engine exhaust gas treatment device characterized by the above. 2. An aqueous solution obtained by dissolving, in clear water, fuel remaining in the supply line of the engine fuel of the ship that has vaporized, or gas volatilized from the cargo in the cargo tank of the ship is used as the reducing agent. The engine exhaust gas treatment device according to the above 1, characterized by the above. 3. The reducing agent is an aqueous ammonia solution, alcohol, or a mixed liquid of an aqueous ammonia solution and alcohol. The engine exhaust gas treatment device according to the above 1, characterized by the above. 4. Urea water is supplied to the inner pipe of the double pipe selectively or in mixture with the reducing agent. The engine exhaust gas treatment device according to the above 1, characterized by the above. 5. The outer pipe of the double-walled piping system is equipped with a level switch for detecting leakage of the reducing agent from the inner pipe, and a pressure sensor or gas sensor. An engine exhaust gas treatment device according to any one of the above 1 to 4, characterized in that 6. A method for treating engine exhaust gas, comprising introducing ship engine exhaust gas into a selective catalytic reduction unit in which a selective catalytic reduction catalyst is arranged, supplying a reducing agent, and performing denitrification treatment on the engine exhaust gas, The reducing agent is supplied to the selective reduction catalyst unit via a nozzle through the inner pipe of the double piping. In the outer pipe of the double-walled piping, an inert gas or atmosphere is circulated in the same direction as the reducing agent. The inert gas or air is supplied to the selective reduction catalyst unit as a dispersion gas for dispersing the reducing agent. A method for treating engine exhaust gas, characterized by the features described above. 7. The reducing agent is an aqueous solution obtained by dissolving fuel remaining in the engine fuel supply line of the aforementioned vessel, or gas that has vaporized from cargo in the cargo tank of the aforementioned vessel, in fresh water. The method for treating engine exhaust gas according to the above 6, characterized by the features described above. 8. As the reducing agent, an aqueous ammonia solution, an alcohol, or a mixed liquid of an aqueous ammonia solution and an alcohol is used. The method for treating engine exhaust gas according to the above 6, characterized by the features described above. 9. Urea water is supplied to the inner pipe of the double-walled piping either selectively with the reducing agent or mixed with the reducing agent. The method for treating engine exhaust gas according to the above 6, characterized by the features described above. 10. The outer pipe of the double-walled piping system is equipped with a level switch for detecting leakage of the reducing agent from the inner pipe, and a pressure sensor or gas sensor. A method for treating engine exhaust gas according to any one of the above 6 to 9, characterized in that [Effects of the Invention]

[0016] In this invention, even if reducing agent leaks from the inner pipe of the double-walled piping system, the leaked reducing agent is supplied to the selective catalytic reduction unit along with the inert gas or atmosphere flowing through the outer pipe, and together with the reducing agent supplied to the selective catalytic reduction unit via the inner pipe, it is used to treat engine exhaust gas. Therefore, unlike conventional systems, there is no need to send the dispersion gas and ventilation gas in opposite directions and send the ventilation gas from the outer pipe of the double-walled piping system to a return pipe for detoxification treatment, resulting in a simpler system configuration. In particular, in the interior of a ship where space efficiency is paramount, having even one fewer pipe or piece of equipment is a significant advantage.

[0017] Therefore, according to the present invention, a reducing agent such as an aqueous ammonia solution or alcohol can be safely supplied to an exhaust gas purification device that purifies NOx (nitrogen oxides) contained in engine exhaust gas, and an engine exhaust gas treatment device and an engine exhaust gas treatment method with a simple device configuration can be provided. [Brief explanation of the drawing]

[0018] [Figure 1] Block diagram showing the configuration of the engine exhaust gas treatment device according to the first embodiment of the present invention. [Figure 2] Block diagram showing the configuration of the engine exhaust gas treatment device according to the second embodiment of the present invention. [Figure 3] A schematic cross-sectional view showing the structure of a confluence pipe applied to an engine exhaust gas treatment device according to a second embodiment of the present invention. [Figure 4] A longitudinal cross-sectional view showing the structure of a piping connection applied to an engine exhaust gas treatment device according to a second embodiment of the present invention. [Figure 5] A cross-sectional view showing the structure of a piping connection applied to an engine exhaust gas treatment device according to a second embodiment of the present invention. [Modes for carrying out the invention]

[0019] Embodiments of the present invention will be described below with reference to the drawings. The various features shown in each of the embodiments below can be combined with each other. The present invention relates to an engine exhaust gas treatment apparatus and an engine exhaust gas treatment method, which involve introducing ship engine exhaust gas into a selective catalytic reduction unit, supplying a reducing agent to the selective catalytic reduction unit, and performing denitrification treatment on the engine exhaust gas. The engine exhaust gas treatment method of the present invention can be carried out using the engine exhaust gas treatment apparatus of the present invention.

[0020] [First Embodiment] Figure 1 is a block diagram showing the configuration of an engine exhaust gas treatment device according to a first embodiment of the present invention. In Figure 1, liquid pathways are shown with solid lines, and gas pathways are shown with dotted lines. The same applies to the other figures.

[0021] The propulsion engine 101 of the ship equipped with this engine exhaust gas treatment device is supplied with fuel from a fuel tank (not shown), and this fuel is burned to generate propulsion for the ship. Examples of fuel for engine 101 include, but are not limited to, liquefied fuels or liquid fuels such as liquefied ammonia, alcohol, LNG, and LPG, and heavy oil may be used alone or in combination with these. Furthermore, engine 101 may be a dual-fuel engine that uses liquefied ammonia fuel or alcohol and fossil fuels such as heavy oil. In a dual-fuel engine, it is possible to selectively switch between a mode in which liquefied ammonia fuel is the main fuel and fossil fuels such as heavy oil are supplied as ignition sources, and a fossil fuel mode in which only fossil fuels are used for operation.

[0022] As shown in Figure 1, the engine exhaust gas emitted from engine 101 passes through exhaust receiver 102 and is discharged into the atmosphere through exhaust pipe 103.

[0023] The engine exhaust gas treatment device of this embodiment includes a selective catalytic reduction (SCR) unit 1. The selective catalytic reduction unit 1 receives engine exhaust gas that has passed through the exhaust receiver 102 and discharges this engine exhaust gas into the exhaust pipe 103.

[0024] A selective catalytic reduction (SCR) is installed inside the selective catalytic reduction unit 1. Engine exhaust gas is introduced and a reducing agent R is supplied, and NO in the engine exhaust gas is reduced by selective catalytic reduction (SCR). X A denitrification treatment is performed by reacting the substance with a reducing agent R.

[0025] Examples of reducing agents R include aqueous ammonia solutions, alcohols, or mixtures of aqueous ammonia solutions and alcohols. Examples of alcohols include methanol, ethanol, and propanol. It should be noted that aqueous ammonia solutions and methanol are known to be toxic, while ethanol and propanol are known to be flammable.

[0026] The reducing agent R is supplied from the reducing agent tank 6 to the inner pipe 3 of the double piping 2 via the supply pump 7 and supply valve 8, outside the safety area (outside the engine room, for example, in the fuel adjustment room). Since this reducing agent R is toxic, for example, in the case of an aqueous ammonia solution, it is supplied via the inner pipe 3 of the double piping 2 in the safety area (engine room) to prevent leakage.

[0027] The reducing agent R is injected into the exhaust receiver 102 or between the exhaust receiver 102 and the selective reduction catalyst via the nozzle 4 through the inner pipe 3 of the double piping 2, and supplied to the selective reduction catalyst.

[0028] Furthermore, a purging liquid or purging gas P can be supplied to the piping between the reducing agent tank 6 and the inner pipe 3 of the double piping 2 via an on-off valve 9 and a check valve 10. The purging liquid or purging gas P is supplied into the piping to remove any remaining reducing agent R after the supply of the reducing agent R has been stopped.

[0029] As the reducing agent R, if the engine fuel is liquefied ammonia or alcohol, an aqueous solution can be used which is obtained by recovering the vaporized fuel gas remaining in the engine fuel supply line and dissolving it in fresh water. Such an aqueous solution can be stored in the reducing agent tank 6. The fresh water may be supplied from outside the ship and stored in the tank, or it may be produced from seawater or the like by a water desalination system on board the ship. Furthermore, methanol does not emit CO2 during its manufacturing process, and its combustion emits approximately 15% less CO2 than heavy oil, resulting in a low environmental impact. Also, as mentioned earlier, ammonia and methanol are produced together in a single process, so they can be used as a mixed fuel on ships, or liquefied ammonia and methanol can be carried separately on the same ship, or they can be mixed and burned when supplied to the engine.

[0030] Furthermore, if the cargo on the ship is liquefied ammonia or alcohol, an aqueous solution obtained by dissolving the gas vaporized from the cargo in fresh water in the cargo tank can be used as the reducing agent R. Such an aqueous solution can be stored in the reducing agent tank 6.

[0031] In addition, the reducing agent tank 6 may also store reducing agent R, which is loaded separately from engine fuel and cargo.

[0032] In the outer pipe 5 of the double-walled piping 2, an inert gas or atmosphere G flows in the same direction as the reducing agent R. The inert gas or atmosphere G is sent from outside the engine room by a blower 11, passes through a check valve 12, and is sent to the outer pipe 5 of the double-walled piping 2. As the inert gas, for example, nitrogen gas, air with a sufficiently reduced oxygen concentration, or argon gas can be used. Considering safety, such as explosion limits, nitrogen gas or air with a sufficiently reduced oxygen concentration is preferred as the gas flowing in the same direction as the reducing agent R.

[0033] An inert gas or atmosphere G is supplied to the selective reduction catalyst unit 1 as a dispersion gas to disperse the reducing agent R within the selective reduction catalyst unit 1. The dispersion gas also serves as the ventilation gas in the outer tube 5 and is used to finely disperse the reducing agent R at the nozzle 4.

[0034] Even if reducing agent R leaks from the inner pipe 3 of the double piping 2, the leaked reducing agent R is supplied to the selective catalytic reduction unit 1 together with the inert gas or atmosphere G flowing through the outer pipe 5, and together with the reducing agent R supplied to the selective catalytic reduction unit 1 via the inner pipe 3, it is used to treat engine exhaust gas. Therefore, in this engine exhaust gas treatment system, it is unnecessary to send the dispersed gas and ventilation gas in opposite directions, as was the case with conventional fuel supply systems, and to send the ventilation gas from the outer pipe of a double-walled piping system to a return pipe for detoxification treatment, resulting in a simpler system configuration. In particular, in the interior of a ship where space efficiency is paramount, having even one fewer pipe or piece of equipment is a significant advantage.

[0035] It is preferable to install a level switch LS and a pressure sensor PT or gas sensor GT inside the outer pipe 5 of the double-walled piping 2 to detect leakage or abnormalities of the reducing agent R from the inner pipe 3.

[0036] The level switch LS detects leakage of the reducing agent R from the inner pipe 3 when the reducing agent R cannot be pushed from the inner pipe 3 into the selective reduction catalyst unit 1, by measuring the change in the level (liquid level) of the reducing agent R in the outer pipe 5. When leakage is detected, the supply pump 7 is stopped, a purging fluid (liquid or gas (hereinafter the same)) P is supplied, and the flow rate of the inert gas or atmospheric air blower 11 is increased to spray the leaked reducing agent R into the selective reduction catalyst unit 1 for denitrification treatment.

[0037] The pressure sensor PT detects a blockage in the nozzle 4 by detecting a change in internal pressure within the outer pipe 5. When a blockage is detected, the supply pump 7 is stopped, purging fluid P is supplied, and maintenance of the piping and nozzle 4 is performed.

[0038] The gas sensor GT detects leakage of reducing agent R from the inner pipe 3 by measuring the change in the concentration of vaporized gas from the reducing agent R in the outer pipe 5. When a leak is detected, the supply pump 7 is stopped, purging fluid P is supplied, and the flow rate of the inert gas or atmospheric air blower 11 is increased to spray the leaked reducing agent R into the selective reduction catalyst unit 1 for denitrification treatment.

[0039] [Second Embodiment] Figure 2 is a block diagram showing the configuration of an engine exhaust gas treatment device according to a second embodiment of the present invention.

[0040] As shown in Figure 2, this embodiment allows urea water to be supplied to the inner pipe 3 of the double piping 2 either selectively with the reducing agent R or mixed with the reducing agent R. The other configurations are the same as in the first embodiment, so we will refer to that explanation and omit them here.

[0041] In this embodiment, urea solution U can be supplied from a urea solution tank (not shown) to the piping between the reducing agent tank 6 and the inner pipe 3 of the double piping 2, via an on-off valve 13 and a check valve 14. The urea solution U is loaded separately from the reducing agent R and stored in the urea solution tank.

[0042] Urea solution U, when supplied to the selective catalytic reduction unit 1, generates ammonia gas and can therefore be used as a reducing agent for denitrification of engine exhaust gas. Although urea solution U is alkaline and has the potential to generate ammonia gas, it is stable and does not have the toxicity of aqueous ammonia.

[0043] The supply to the inner pipe 3 can be configured as follows: by operating the supply pump 7, opening the supply valve 8 and closing the on-off valve 13, only the reducing agent R can be supplied; by stopping the supply pump 7, closing the supply valve 8 and opening the on-off valve 13, only the urea solution U can be supplied; or by operating the supply pump 7, opening the supply valve 8 and the on-off valve 13, a mixture of the reducing agent R and the urea solution U can be supplied.

[0044] In this embodiment, if the engine fuel is liquefied ammonia or alcohol, and an aqueous solution of the gas remaining in the engine fuel supply line is used as the reducing agent R, then it may not be possible to secure a sufficient amount of the reducing agent R for the denitrification treatment of the engine exhaust gas in the selective catalytic reduction unit 1. This is because the recovery of the gas remaining in the engine fuel supply line can only be done when the engine 101 is stopped. In this embodiment, since urea solution U is loaded separately from the reducing agent R, as long as a sufficient amount of urea solution U is loaded, the selective catalytic reduction unit 1 will not be unable to perform denitrification treatment of engine exhaust gas.

[0045] In this embodiment, in areas subject to Tier 3 regulations, urea solution U and reducing agent R are supplied to ensure denitrification in the selective reduction catalyst unit 1, thereby satisfying the regulations, and allowing for onboard treatment of an aqueous solution (reducing agent R) of gas remaining in the engine fuel supply line generated on the ship. In areas subject to Tier 2 regulations, complete denitrification is not required. Therefore, only reducing agent R is supplied, and the aqueous solution of gas (reducing agent R) remaining in the engine fuel supply line generated on board the vessel is treated onboard.

[0046] [Structure of combined sewer pipes] Figure 3 is a schematic cross-sectional view showing the structure of a confluence piping applied to an engine exhaust gas treatment device according to a second embodiment of the present invention.

[0047] In the second embodiment, the piping for the reducing agent R and the urea solution U may be configured to merge immediately before supplying them to the selective reduction catalyst unit 1, as shown in Figure 3.

[0048] In this example, the pipe connection 15 between the double piping 20 and the selective reduction catalyst unit 1 is preferably a sanitary structure or a flange type, taking into consideration the maintenance of the lance 16 leading to the nozzle 4 inside the selective reduction catalyst unit 1. A sanitary structure is a structure in which dirt is less likely to remain because there are no small gaps into which dirt or cleaning fluid can enter, and a structure that is easy to clean because it is easy to disassemble.

[0049] In this example, the reducing agent R is supplied from the reducing agent tank 6 to the inner pipe 3 of the double piping 2 by the supply pump 7, outside the safety zone, as in the first embodiment.

[0050] Similar to the first embodiment, a purging liquid or purging gas P can be supplied to the piping between the reducing agent tank 6 and the inner pipe 3 of the double piping 2 via the on-off valve 9 and the check valve 10.

[0051] Similar to the first embodiment, a level switch LS is installed in the outer pipe 5 of the double-walled piping 2 to detect leakage or abnormalities of the reducing agent R from the inner pipe 3. However, in this example, when the level switch LS detects a change in the level of the reducing agent R in the outer pipe 5, indicating leakage of the reducing agent R from the inner pipe 3, the leaked reducing agent R is not only sent to the selective reduction catalyst unit 1 but also returned to the reducing agent tank 6 via the on-off valve 18. The on-off valve 18 is normally closed and opens when leakage of the reducing agent R from the inner pipe 3 is detected.

[0052] The outer pipe 5 of the double-walled piping 2 is supplied with an inert gas for reducing agent or air G via a blower 11 and an on / off valve 19 outside the safety area. R The solution is sent and flows through the outer tube 5 in the same direction as the reducing agent R.

[0053] The double piping 2 is connected to a sealed box 17 within a safe area. Inside box 17, the outer pipe 5 is in communication with the inside of box 17, and the inner pipe 3 passes through box 17 as is and exits box 17. Inside box 17, the inner pipe 3 passes through supply valve 8 and exits box 17. A pressure sensor PT may be provided in the inner pipe 3, upstream of the supply valve 8.

[0054] Furthermore, the double piping 2 is connected at a height along the bottom of box 17 so that if liquid leaks into box 17, the leaked liquid will return to the reducing agent tank 6 side via the outer pipe 5. Also, the reducing agent tank 6 side of the double piping 2 is lower than the box 17 side so that the leaked liquid in the outer pipe 5 returns to the reducing agent tank 6 side.

[0055] Within box 17, the supply pipe for urea solution U joins the inner pipe 3 downstream of the supply valve 8. The urea solution U enters the inner pipe 3 via the on / off valve 13.

[0056] At the outlet from box 17, an outer pipe surrounds the inner pipe 3, forming a double-walled pipe 20. The outer pipe of the double-walled pipe 20 is not connected to the inside of the box. The outer pipe of the double-walled pipe 20 is supplied with inert gas for urea solution or air G via an on-off valve 21. U The urea solution U is sent and flows through the outer pipe in the same direction as the urea solution U toward the selective reduction catalyst unit 1. Between the on-off valve 21 and the outer pipe of the double piping 20 (downstream of the on-off valve 21), there is a junction 23 that communicates with the inside of the box 17 via the on-off valve 22. The box 17 is also equipped with a pressure alarm sensor PIA that detects the internal pressure of the box 17. The box 17 may also be equipped with a gas sensor GT.

[0057] Box 17 functions as the outer pipe of the double piping, thus ensuring safety. The inert gas or atmosphere G for the reducing agent is supplied by the outer pipe 5 of the double piping 2. RThe contents are sent into box 17, and after passing through the on-off valve 22 and the junction 23, are sent into the outer pipe of the double piping 20 that leads from box 17 to the selective reduction catalyst unit 1.

[0058] The double-walled pipe 20 leading from box 17 to the selective catalytic reduction unit 1 is connected to the lance 16 inside the selective catalytic reduction unit 1 via a pipe connection 15. The pipe connection 15 is located on the outer wall surface of the selective catalytic reduction unit 1. The lance 16 has a double-walled structure, with the inner pipe connected to the inner pipe of the double-walled pipe 20 and the outer pipe connected to the outer pipe of the double-walled pipe 20. A nozzle 4 is attached to the tip of the inner pipe of the lance 16. The tip of the outer pipe of the lance 16 is open into the selective catalytic reduction unit 1.

[0059] Figure 4 is a longitudinal cross-sectional view showing the structure of a piping connection applied to an engine exhaust gas treatment device according to a second embodiment of the present invention. Figure 5 is a cross-sectional view showing the structure of a piping connection applied to an engine exhaust gas treatment device according to a second embodiment of the present invention.

[0060] The pipe connection section 15 can have a flange-type structure, as shown in Figures 4 and 5. This pipe connection section 15 consists of a first member 27 and a second member 31. The first member 27 consists of an inner cylinder 24 connected to the inner pipe of the double pipe 20, an outer cylinder 25 connected to the outer pipe of the double pipe 20, and disc-shaped flange portions 26 formed at the ends of the inner cylinder 24 and the outer cylinder 25. The second member 31 consists of an inner cylinder 28 connected to the inner pipe of the lance 16, an outer cylinder 29 connected to the outer pipe of the lance 16, and disc-shaped flange portions 30 formed at the ends of the inner cylinder 28 and the outer cylinder 29. From the viewpoint of preventing leakage of gas and liquid, it is preferable that the first member 27 and the second member 31 be integrally formed by machining from a metal rod.

[0061] The flange portion 26 of the first member 27 and the flange portion 30 of the second member 31 each have through holes formed in their centers that connect to the inner cylinder hole 32. In addition, the flange portion 26 and the flange portion 30 each have multiple outer cylinder holes 33 formed inside the outer cylinders 25 and 29 and outside the inner cylinders 24 and 28, and multiple bolt holes 34 formed outside the outer cylinders 25 and 29.

[0062] In this pipe connection section 15, the first member 27 and the second member 31 are joined together with their flange portions 26 and 30 abutted, with an outer O-ring 35a and an inner O-ring 35b acting as packing in between. At this time, the through holes connected to the inner cylinder holes 32, 32 are connected, the multiple outer cylinder holes 33, 33 are connected, and the multiple bolt holes 34, 34 are connected. The outer O-ring 35a seals the space between the multiple outer cylinder holes 33, 33 and the outside of the pipe, and the inner O-ring 35b seals the space between the through holes connected to the inner cylinder holes 32, 32 and the multiple outer cylinder holes 33, 33.

[0063] Then, by passing bolts through the multiple bolt holes 34, 34 and fastening them with nuts, the first member 27 and the second member 31 are fixed to each other, forming the pipe connection section 15. Through holes connected to the inner cylindrical holes 32, 32, the reducing agent R and urea solution U pass through. Multiple outer cylindrical holes 33, 33 allow the reducing agent inert gas or air G to pass through. R and inert gas or air for urea solution G U It passes through. Furthermore, it is preferable that the double pipe 20 and lance 16 connected to the pipe connection part 15 have a larger outer pipe diameter only at the connection part, and a smaller diameter elsewhere.

[0064] When supplying only the reducing agent R to the selective reduction catalyst unit 1, the supply pump 7 is activated and the supply valve 8 is opened to deliver the reducing agent R, and the on-off valves 19 and 22 are opened to supply the reducing agent inert gas or air G. R The system sends the gas, closes valve 13 to stop the urea solution U, and closes valve 21 to supply the inert gas or air G for the urea solution. U Stop that too.

[0065] When only the aqueous urea U is supplied to the selective reduction catalyst unit 1, the supply pump 7 is stopped, the supply valve 8 is closed to stop the reducing agent R, the on-off valves 19 and 22 are closed to stop the inert gas or air G for the reducing agent R and the on-off valve 13 is opened to send the aqueous urea U, and the on-off valve 21 is opened to send the inert gas or air G for the aqueous urea U .

[0066] When the reducing agent R and the aqueous urea U are mixed and supplied to the selective reduction catalyst unit 1, the supply pump 7 is operated, the supply valve 8 is opened to send the reducing agent R, the on-off valves 19 and 22 are opened to send the inert gas or air G for the reducing agent R and the on-off valve 13 is opened to send the aqueous urea U, and the on-off valve 21 is opened to send the inert gas or air G for the aqueous urea U .

[0067] The pressure alarm sensor PIA detects clogging as a change in the internal pressure in the outer pipe 5 and the box 17 when clogging occurs in the inert gas or air G for the reducing agent at the nozzle 4 R . When clogging is detected, the supply pump 7 is stopped, the purge fluid P is supplied, and maintenance of the piping and the nozzle 4 is performed, etc.

[0068] The level switch LS detects leakage of the reducing agent R from the inner pipe 3 as a change in the level (liquid level position) of the reducing agent R in the outer pipe 5 when the reducing agent R cannot be pushed into the selective reduction catalyst unit 1 from the inner pipe 3. When leakage is detected, the supply pump 7 is stopped, the supply valve 8 is closed to stop the supply of the reducing agent R, the on-off valve 13 is opened to switch to the supply of the aqueous urea U, and the on-off valve 21 is opened to send the inert gas or air G for the aqueous urea U . The reducing agent R leaked into the outer pipe 5 and the box 17 of the double pipe 2 is returned to the reducing agent tank 6 by opening the on-off valve 18. Also, at this time, the purge fluid P may be supplied, and the flow rate of the blower 11 for the inert gas or air G for the reducing agent R may be increased to remove the leaked reducing agent R.

[0069] The pressure sensor PT detects a blockage inside the nozzle 4 by detecting a change in internal pressure within the inner pipe 3. When a blockage is detected, the supply pump 7 is stopped, purging fluid P is supplied, and maintenance of the piping and nozzle 4 is performed.

[0070] The gas sensor GT detects leakage of reducing agent R from the inner pipe 3 by measuring the change in the concentration of vaporized gas from the reducing agent R in the outer pipe 5 and box 17. When a leak is detected, the supply pump 7 is stopped, purging fluid P is supplied, and the flow rate of the inert gas or atmospheric air blower 11 is increased to spray the leaked reducing agent R into the selective reduction catalyst unit 1 for denitrification treatment. [Explanation of Symbols]

[0071] 1. Selective catalytic reduction unit 2 Double piping 3 Inner tube 4 nozzles 5 Outer tube 6. Reducing agent tank 7. Supply pump 8. Supply valve 9. Shut-off valves 10 Check valve 11 Blower 12 Check valve 13. Shut-off valves 14. Check valve 15. Pipe connection section 16 Lance 17 boxes 18. Shut-off valve 19. Shut-off valves 20 Double piping 21. Shut-off valves 22 Shut-off valves 23. Confluence 24, 28 Inner cylinder 25, 29 Outer cylinder 26, 30 Flange section 27 First member 31 Second member 32 Inner cylinder hole 33 Outer cylinder hole 34 bolt holes 35a Outer circumference O-ring 35b Inner circumference O-ring 101 Engine 102 Exhaust Receiver 103 Exhaust pipe R reducing agent G Inert gas or atmosphere P purging liquid or purging gas LS Level Switch PT pressure sensor GT gas sensor PIA Pressure Alarm Sensor

Claims

1. A selective catalytic reduction unit is provided in which the exhaust gas from a ship's engine is introduced, a reducing agent is supplied, and a selective catalytic reduction treatment is performed on the engine exhaust gas. The reducing agent is supplied to the selective reduction catalyst unit via a nozzle through the inner pipe of the double piping. The outer pipe of the double-walled piping communicates with a sealed box, and the inner pipe of the double-walled piping passes through the box as is and exits the box. Inside the box, a urea water supply pipe joins the inner pipe, and the urea water is supplied to the inner pipe either selectively with the reducing agent or mixed with the reducing agent. The outlet portion from the box is provided with an outer pipe surrounding the inner pipe, forming a double-walled piping system, through which an inert gas or atmosphere flows in the same direction as the reducing agent in the outer pipe of this double-walled piping system. The inert gas or air is supplied to the selective reduction catalyst unit as a dispersion gas for dispersing the reducing agent and / or the urea solution. An engine exhaust gas treatment device characterized by the following features.

2. The reducing agent is an aqueous solution obtained by dissolving fuel remaining in the engine fuel supply line of the aforementioned vessel, or gas that has vaporized from cargo in the cargo tank of the aforementioned vessel, in fresh water. The engine exhaust gas treatment device according to claim 1, characterized in that it is as described above.

3. The reducing agent is an aqueous ammonia solution, an alcohol, or a mixed liquid of an aqueous ammonia solution and an alcohol. The engine exhaust gas treatment device according to claim 1, characterized in that it is as described above.

4. The double piping leading from the box to the selective catalytic reduction unit is connected to a lance in the selective catalytic reduction unit 1 by a piping connection consisting of a first member and a second member. The first member comprises an inner cylinder connected to the inner pipe of the double piping, an outer cylinder connected to the outer pipe of the double piping, and a disc-shaped flange portion formed at the ends of the inner and outer cylinders, with a through hole in the center connected to the inner cylinder hole and a plurality of outer cylinder holes formed inside the outer cylinder at a position outside the inner cylinder. The second member comprises an inner cylinder connected to the inner tube of the lance, an outer cylinder connected to the outer tube of the lance, and a disc-shaped flange portion formed at the ends of the inner and outer cylinders, with a through hole in the center connected to the inner cylinder hole and a plurality of outer cylinder holes formed inside the outer cylinder at positions outside the inner cylinder. The first member and the second member are abutted against each other at their respective flange portions, their through holes leading to the inner cylindrical bore are connected, and the multiple outer cylindrical bore is connected to each other. The engine exhaust gas treatment device according to claim 1, characterized in that it is as described above.

5. The outer pipe of the double-walled piping system is equipped with a level switch for detecting leakage of the reducing agent from the inner pipe, and a pressure sensor or gas sensor. An engine exhaust gas treatment device according to any one of features 1 to 4.

6. A method for treating engine exhaust gas, comprising introducing ship engine exhaust gas into a selective catalytic reduction unit in which a selective catalytic reduction catalyst is arranged, supplying a reducing agent, and performing denitrification treatment on the engine exhaust gas, The reducing agent is supplied to the selective reduction catalyst unit via a nozzle through the inner pipe of the double piping. The outer pipe of the double-walled piping is connected to a sealed box, the inner pipe of the double-walled piping is passed through the box as is and out of the box, a urea water supply pipe is joined to the inner pipe, and the urea water is supplied to the inner pipe either selectively with the reducing agent or mixed with the reducing agent. The outlet portion from the box is provided with an outer pipe surrounding the inner pipe to form a double-walled pipe, and an inert gas or atmosphere is circulated through the outer pipe of this double-walled pipe in the same direction as the reducing agent. The inert gas or air is supplied to the selective reduction catalyst unit as a dispersion gas for dispersing the reducing agent and / or the urea solution. A method for treating engine exhaust gas, characterized by the features described above.

7. The reducing agent is an aqueous solution obtained by dissolving fuel remaining in the engine fuel supply line of the aforementioned vessel, or gas that has vaporized from cargo in the cargo tank of the aforementioned vessel, in fresh water. The method for treating engine exhaust gas according to claim 6, characterized in that it is described in the present invention.

8. As the reducing agent, an aqueous ammonia solution, an alcohol, or a mixed liquid of an aqueous ammonia solution and an alcohol is used. The method for treating engine exhaust gas according to claim 6, characterized in that it is described in the present invention.

9. The double piping leading from the box to the selective reduction catalyst unit is connected to a lance in the selective reduction catalyst unit 1 by a piping connection part consisting of a first member and a second member. The first member comprises an inner cylinder connected to the inner pipe of the double piping, an outer cylinder connected to the outer pipe of the double piping, and a disc-shaped flange portion formed at the ends of the inner and outer cylinders, with a through hole in the center connected to the inner cylinder hole and a plurality of outer cylinder holes formed inside the outer cylinder at a position outside the inner cylinder. The second member comprises an inner cylinder connected to the inner tube of the lance, an outer cylinder connected to the outer tube of the lance, and a disc-shaped flange portion formed at the ends of the inner and outer cylinders, with a through hole in the center connected to the inner cylinder hole and a plurality of outer cylinder holes formed inside the outer cylinder at positions outside the inner cylinder. The first member and the second member are brought together by butting their respective flange portions, connecting the through holes that lead to the inner cylindrical holes, and connecting the multiple outer cylindrical holes. The method for treating engine exhaust gas according to claim 6, characterized in that it is described in the present invention.

10. The outer pipe of the double-walled piping system is equipped with a level switch for detecting leakage of the reducing agent from the inner pipe, and a pressure sensor or gas sensor. A method for treating engine exhaust gas according to any one of claims 6 to 9.

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