Drain treatment device

Abstract

To provide a drain treatment device capable of effectively utilizing an ammonia component of an ammonia-containing drain recovered from a fuel injection system of a marine diesel engine.SOLUTION: A drain treatment device, which is one embodiment of the present invention, includes: a recovery part which communicates with a fuel injection system for spraying ammonia fuel and fossil fuel into a combustion chamber of a marine diesel engine, and which recovers an ammonia-containing drain discharged from the fuel injection system; and a supply part that supplies an ammonia component, included in the recovered ammonia-containing drain, to one or more functional parts functioning by utilizing the ammonia component.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a drain treatment device applied to a marine diesel engine.

Background Art

[0002] In recent years, in the field of ships, as one of the methods for reducing the emission amount of greenhouse gases (GHG: Greenhouse Gas) discharged from marine diesel engines, there is an ammonia co-firing technology. The ammonia co-firing technology is to inject a conventional fossil fuel such as heavy oil, which is adopted as a marine fuel, and an ammonia fuel that does not generate carbon dioxide (one of the GHGs) even when burned, into the combustion chamber of a marine diesel engine and burn them together. Thereby, the content of carbon dioxide (that is, the emission amount of carbon dioxide) contained in the exhaust gas from the marine diesel engine can be reduced.

[0003] In a marine diesel engine adopting such an ammonia co-firing technology, generally, drain containing ammonia fuel (hereinafter referred to as ammonia-containing drain) is discharged from a fuel injection valve or the like that injects fossil fuel and ammonia fuel into the combustion chamber. Then, the discharged ammonia-containing drain is recovered in a container such as a tank. For example, Patent Document 1 discloses a drain system that recovers ammonia-containing drain (fuel drain) discharged from a fuel injection valve into a tank through a pipe, and incinerates the ammonia component (ammonia gas) that has volatilized from the recovered ammonia-containing drain with a boiler.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, as mentioned above, if the ammonia component of the recovered ammonia-containing drain is incinerated, it can be treated without releasing harmful ammonia gas into the atmosphere, but the incineration of the ammonia component generates nitrogen oxides (N2O, etc.). Furthermore, if the ammonia component is not incinerated in order to avoid an increase in the amount of nitrogen oxides generated (discharged from the ship), the recovered ammonia-containing drain must be stored in a sealed container on board the ship and eventually unloaded for treatment, which would incur significant costs for the treatment of the ammonia-containing drain.

[0006] In recent years, there has been a growing demand to reduce carbon dioxide emissions from marine diesel engines, and consequently, there is a need to effectively utilize the ammonia components of the ammonia-containing drain recovered as described above.

[0007] The present invention has been made in view of the above circumstances, and aims to provide a drain treatment device that can effectively utilize the ammonia component of ammonia-containing drain recovered from the fuel injection system of a marine diesel engine. [Means for solving the problem]

[0008] To solve the above-mentioned problems and achieve the objective, the drain treatment device according to the present invention is characterized by comprising: a recovery unit that communicates with a fuel injection system for injecting ammonia fuel and fossil fuel into the combustion chamber of a marine diesel engine and recovers ammonia-containing drain discharged from the fuel injection system; and a supply unit that supplies the ammonia component contained in the recovered ammonia-containing drain to one or more functional units that function using the ammonia component.

[0009] Furthermore, the drain treatment apparatus according to the present invention is characterized in that the recovery unit comprises at least one recovery pipe through which a mixed drain, which is a mixture of a gaseous component other than the ammonia component or an oily component, and the ammonia fuel, flows, and a recovery tank that recovers the mixed drain from the fuel injection system through the at least one recovery pipe and stores the ammonia-containing drain, which contains at least one of the gaseous component and the oily component and the ammonia fuel.

[0010] Furthermore, the drain treatment apparatus according to the present invention is characterized in that, in the above invention, the recovery tank is a gas-liquid separator that separates the stored ammonia-containing drain into an ammonia-containing liquid containing the oil component and the ammonia fuel, and an ammonia-containing gas containing the gaseous component and ammonia gas vaporized from the ammonia fuel, and the supply unit comprises an extraction unit that removes the oil component from the ammonia-containing liquid to extract the ammonia component, and an ammonia water generation unit that adds water to the ammonia-containing gas to separate the gaseous component and the ammonia gas, and generates ammonia water which is an aqueous solution of the ammonia gas and contains the ammonia component.

[0011] Furthermore, the drain treatment apparatus according to the present invention is an exhaust gas treatment apparatus comprising, in the above invention, one of the one or more functional units is a reactor that removes nitrogen oxides contained in exhaust gas by a reduction reaction between nitrogen oxides and a reducing agent, a mixer that mixes the exhaust gas and the reducing agent, and a reducing agent supply unit that supplies the reducing agent to the mixer, wherein the supply unit supplies the ammonia component extracted by the extraction unit to the mixer.

[0012] Furthermore, the drain treatment apparatus according to the present invention is characterized in that, in the above invention, the supply unit adds the ammonia water generated by the ammonia water generation unit to the reducing agent.

[0013] Furthermore, the drain treatment device according to the present invention is characterized in that, in the above invention, one of the one or more functional units is a drive system for a marine diesel engine that generates driving force by utilizing the energy from the co-combustion of the ammonia fuel and the fossil fuel injected into the combustion chamber, and the supply unit injects the ammonia water produced by the ammonia water generation unit into the combustion chamber.

[0014] Furthermore, the drain treatment device according to the present invention is characterized in that, in the above invention, the at least one recovery pipe includes a first recovery pipe that recovers a first mixed drain, which is a mixture of the fossil fuel and the ammonia fuel, from the fuel injection valve of the fuel injection system.

[0015] Furthermore, the drain treatment device according to the present invention is characterized in that, in the above invention, the at least one recovery pipe includes a second recovery pipe that recovers a second mixed drain, which is a mixture of the lubricating oil of the ammonia pump and the ammonia fuel, from the ammonia pump that pressurizes the ammonia fuel to the fuel injection valve of the fuel injection system.

[0016] Furthermore, the drain treatment device according to the present invention is characterized in that, in the above invention, the at least one recovery pipe includes a third recovery pipe that recovers a third mixed drain, which is a mixture of purge gas purging the inside of the communication pipe and the ammonia fuel, from a communication pipe that connects the fuel injection valve of the fuel injection system and an ammonia pump that pressurizes the ammonia fuel to the fuel injection valve.

[0017] Furthermore, the drain treatment apparatus according to the present invention is characterized in that, in the above invention, the ammonia-containing drain is ammonia water containing the ammonia component, and the supply unit supplies the ammonia water to the one or more functional units.

[0018] Furthermore, the drain treatment device according to the present invention is characterized in that, in the above invention, the fuel injection system comprises a fuel injection valve for injecting the ammonia fuel and the fossil fuel into the combustion chamber, an ammonia pump for pressurizing the ammonia fuel to the fuel injection valve, an ammonia fuel tank for storing the ammonia fuel supplied to the ammonia pump, a double pipe having a first inner pipe connecting the fuel injection valve and the ammonia pump, a first outer pipe that airtightly covers the first inner pipe, a second inner pipe connecting the ammonia pump and the ammonia fuel tank, and a second outer pipe that airtightly covers the second inner pipe, and the recovery unit airtightly covers the ammonia pump and communicates with the double pipe and recovers the ammonia water from the double pipe.

[0019] Furthermore, the drain treatment device according to the present invention is characterized in that, in the above invention, one of the one or more functional units is a collecting tank that stores and neutralizes the acidic scrubber water used for cleaning a portion of the exhaust gas discharged from the marine diesel engine with scrubber water and returns it to the marine diesel engine in an EGR device, and the supply unit supplies the ammonia water to the collecting tank.

[0020] Furthermore, the drain treatment device according to the present invention is characterized in that, in the above invention, one of the one or more functional units is a drive system for a marine diesel engine that generates driving force by utilizing the energy from the co-combustion of the ammonia fuel and the fossil fuel injected into the combustion chamber, and the supply unit injects the ammonia water into the combustion chamber. [Effects of the Invention]

[0021] According to the present invention, the ammonia component of ammonia-containing drain recovered from the fuel injection system of a marine diesel engine can be effectively utilized. [Brief explanation of the drawing]

[0022] [Figure 1]FIG. 1 is a diagram showing a configuration example of a drain treatment device according to Embodiment 1 of the present invention. [Figure 2] FIG. 2 is a diagram showing a configuration example of a drain treatment device according to Embodiment 2 of the present invention. [Figure 3] FIG. 3 is a diagram showing a configuration example of a drain treatment device according to Embodiment 3 of the present invention. [Figure 4] FIG. 4 is a diagram showing a configuration example of a drain treatment device according to Embodiment 4 of the present invention. **[Mode for Carrying Out the Invention]**

[0023] Hereinafter, with reference to the accompanying drawings, preferred embodiments of the drain treatment device according to the present invention will be described in detail. Note that the present invention is not limited by this embodiment. Also, the drawings are schematic, and it should be noted that the dimensional relationships between elements, the ratios of each element, etc. may be different from the actual ones. There may also be parts where the dimensional relationships and ratios are different between the drawings. In each drawing, the same reference numerals are assigned to the same constituent parts.

[0024] (Embodiment 1) The drain treatment device according to Embodiment 1 of the present invention will be described. FIG. 1 is a diagram showing a configuration example of the drain treatment device according to Embodiment 1 of the present invention. In FIG. 1, in addition to the drain treatment device 20 according to the present Embodiment 1, a marine diesel engine 1 to which this drain treatment device 20 is applied and an exhaust gas treatment device 10 applied to this marine diesel engine 1 are shown. Examples of this exhaust gas treatment device 10 include an SCR device which is a selective catalytic reduction (SCR) device. Hereinafter, the marine diesel engine 1 and the exhaust gas treatment device 10 will be sequentially described, and then the drain treatment device 20 will be described.

[0025] (Marine Diesel Engine) The marine diesel engine 1 is a propulsion engine (main engine) that drives and rotates the propeller of a ship via a propeller shaft. Specifically, the marine diesel engine 1 is a two-stroke diesel engine, exemplified by a uniflow scavenging crosshead type diesel engine, and is particularly an ammonia co-firing engine that is driven by the co-firing of ammonia fuel and fossil fuels. Fossil fuels refer to all fuels that can be refined from crude oil, such as diesel fuel, distillates, and residual oils. For example, as shown in Figure 1, the marine diesel engine 1 comprises a drive system 2 and a fuel injection system 3.

[0026] The drive system 2 generates driving force by co-combusting ammonia fuel injected from the fuel injection system 3 and fossil fuels, and utilizing the resulting combustion energy. For example, as shown in Figure 1, the drive system 2 comprises a cylinder 2a, a piston 2b, and a combustion chamber 2c. The cylinder 2a is a cylindrical structure that houses the piston 2b. The combustion chamber 2c of the marine diesel engine 1 is partitioned inside the cylinder 2a by the cylinder 2a and the piston 2b. The piston 2b is configured to reciprocate inside the cylinder 2a while facing the combustion chamber 2c. Although not specifically shown, the lower part of the piston 2b is connected to the crankshaft via a piston rod and a crosshead, etc. Also, as shown in Figure 1, the drive system 2 is equipped with an exhaust valve 2d at the top of the cylinder 2a. The exhaust valve 2d is a valve that can open and close the exhaust port of the cylinder 2a leading to the combustion chamber 2c, and is driven to open and close by a valve train (not shown).

[0027] Although Figure 1 shows one drive system 2, the marine diesel engine 1 may have one drive system 2 or multiple drive systems 2.

[0028] The fuel injection system 3 is a system for injecting ammonia fuel and fossil fuel into the combustion chamber 2c of the marine diesel engine 1. For example, as shown in Figure 1, the fuel injection system 3 includes a fuel injection valve 4, a fuel pump 5a, an ammonia pump 5b, a connecting pipe 6, a double pipe 7, an ammonia fuel tank 8, and a purge section 9.

[0029] As shown in Figure 1, the fuel injector 4 is installed in the cylinder 2a with its nozzle facing into the combustion chamber 2c. Although not specifically shown, the fuel injector 4 has a fuel passage inside that leads to the nozzle. The connecting pipe 6 is a pipe that connects the fuel passage of the fuel injector 4 to the fuel pump 5a. The fuel pump 5a receives fossil fuel from a fuel tank (not shown) through piping and pumps the supplied fossil fuel to the fuel injector 4 through the connecting pipe 6. The pumped fossil fuel fills the fuel passage of the fuel injector 4.

[0030] Furthermore, the fuel injector 4, the ammonia pump 5b, and the ammonia fuel tank 8 are connected via a double pipe 7. More specifically, as shown in Figure 1, the double pipe 7 comprises a first inner pipe 7a connecting the fuel path of the fuel injector 4 to the ammonia pump 5b, a first outer pipe 7b that airtightly covers the first inner pipe 7a, a second inner pipe 7c connecting the ammonia pump 5b to the ammonia fuel tank 8, and a second outer pipe 7d that airtightly covers the second inner pipe 7c. The ammonia fuel tank 8 is a tank that stores liquid ammonia as ammonia fuel supplied to the ammonia pump 5b, and is located, for example, inside a ship and outside the marine diesel engine 1. The ammonia fuel tank 8 supplies ammonia fuel to the ammonia pump 5b through the second inner pipe 7c of the double pipe 7. For example, as shown in Figure 1, the second inner pipe 7c is piped to have a downward slope from the ammonia fuel tank 8 towards the ammonia pump 5b. The ammonia fuel tank 8 uses gravity to supply ammonia fuel from the second inner pipe 7c to the ammonia pump 5b. The ammonia pump 5b pumps the ammonia fuel supplied from the ammonia fuel tank 8 through the first inner pipe 7a of the double pipe 7 to the fuel injector 4. The pumped ammonia fuel is then injected into the fossil fuel filling the fuel path of the fuel injector 4.

[0031] In the double-walled pipe 7 described above, the first outer pipe 7b prevents the liquid and gaseous components (hereinafter collectively referred to as ammonia components) of the ammonia fuel, which are pumped from the ammonia pump 5b through the first inner pipe 7a to the fuel path of the fuel injector 4, from leaking outside the double-walled pipe 7. The second outer pipe 7d prevents the ammonia components of the ammonia fuel supplied from the ammonia fuel tank 8 to the ammonia pump 5b through the second inner pipe 7c from leaking outside the double-walled pipe 7.

[0032] Here, the fuel injector 4, with its fuel path filled with fossil fuel and ammonia fuel, injects the fossil fuel and ammonia fuel from the fuel path into the combustion chamber 2c by the pressure of the fossil fuel again pumped from the fuel pump 5a. At this time, the fuel injector 4 injects the fossil fuel and ammonia fuel in alternating layers, for example. In the drive system 2, the fossil fuel and ammonia fuel injected into the combustion chamber 2c are mixed with combustion gas (compressed gas) supplied to the combustion chamber 2c from the scavenging port (not shown) of the cylinder 2a. The piston 2b reciprocates inside the cylinder 2a by the combustion energy generated by the mixing of these fossil fuels and ammonia fuels. As a result, the drive system 2 generates a driving force. The exhaust valve 2d opens the exhaust port of the cylinder 2a and discharges exhaust gas from the combustion chamber 2c to the outside of the cylinder 2a. The exhaust gas discharged is temporarily stored in the exhaust manifold (not shown) of the marine diesel engine 1 via piping from cylinder 2a.

[0033] The purge section 9 is for removing ammonia fuel remaining inside the first inner pipe 7a of the double pipe 7 when the marine diesel engine 1 stops. For example, as shown in Figure 1, the purge section 9 comprises a purge gas inlet 9a, an outlet pipe 9b, and an on-off valve 9c. As shown in Figure 1, the purge gas inlet 9a is configured to communicate with the vicinity of the connection point to the ammonia pump 5b in the first inner pipe 7a via piping. The purge gas inlet 9a introduces purge gas into the first inner pipe 7a for purging the inside of the first inner pipe 7a. Examples of such purge gas include nitrogen gas. Also, as shown in Figure 1, the outlet pipe 9b is piped to communicate with the vicinity of the connection point to the fuel injection valve 4 in the first inner pipe 7a. The on-off valve 9c is provided in the middle of this outlet pipe 9b.

[0034] Here, when the marine diesel engine 1 stops (normal stop) or makes an emergency stop according to the operator's command, the purge unit 9 opens the on-off valve 9c and introduces purge gas into the first inner pipe 7a from the purge gas introduction unit 9a. The ammonia fuel remaining inside the first inner pipe 7a is pushed out from the first inner pipe 7a to the outlet pipe 9b by the introduced purge gas. In this way, the ammonia fuel is removed from inside the first inner pipe 7a and then discharged from the fuel injection system 3 through the outlet pipe 9b along with the purge gas.

[0035] Although not shown in Figure 1, the marine diesel engine 1 is equipped with a ventilation system for ventilating the internal space of the double-walled pipe 7. This ventilation system releases ammonia gas, which is vaporized ammonia fuel leaking from at least one of the first inner pipe 7a and the second inner pipe 7c, into the space outside the ship through ventilation. When ventilating the internal space of the double-walled pipe 7, this ventilation system may also inject water into the ammonia gas drawn in from this internal space to convert the ammonia gas into ammonia water, thereby preventing the ammonia gas from leaking to the outside of the double-walled pipe 7. This ammonia water may be recovered by a drain treatment device 20 or stored in a predetermined tank.

[0036] (Exhaust gas treatment device) The exhaust gas treatment device 10 is a device that reduces nitrogen oxides (such as NOx and N2O) in the exhaust gas emitted from the marine diesel engine 1, and comprises, for example, a reactor 11, a mixer 12, a reducing agent supply unit 13, and an exhaust pipe 19, as shown in Figure 1.

[0037] Reactor 11 is composed of a catalytic reactor having a catalyst layer and is located downstream of mixer 12, as shown in Figure 1. Reactor 11 receives exhaust gas mixed with a reducing agent from mixer 12 and selectively promotes (accelerates) the reduction reaction between nitrogen oxides in the received exhaust gas and the reducing agent through catalytic action. In this way, reactor 11 removes (denitrifies) nitrogen oxides from the exhaust gas and reduces the amount of nitrogen oxides emitted. Examples of nitrogen oxides denitrified by reactor 11 include NOx generated by the combustion of fossil fuels, N2O generated by the combustion of ammonia fuel, and N2O from the combustion of ammonia components contained in ammonia-containing drain recovered from marine diesel engine 1 by the drain treatment device 20 described later. Also, as shown in Figure 1, an exhaust pipe 19 is connected to the outlet of reactor 11. The exhaust pipe 19 is a pipe that leads to the ship's chimney (not shown) and discharges the exhaust gas (exhaust gas with reduced nitrogen oxides) sent from the reactor 11 to the outside of the ship via the chimney.

[0038] Mixer 12 mixes exhaust gas with a reducing agent. More specifically, as shown in Figure 1, mixer 12 has a reducing agent injection unit 12a inside. Mixer 12 is connected to a discharge pipe 12b and an exhaust pipe 101, and a supply pipe 18 is connected to the reducing agent injection unit 12a. Mixer 12 communicates with a marine diesel engine 1 (e.g., exhaust manifold) via the exhaust pipe 101 and receives exhaust gas from the marine diesel engine 1 through the exhaust pipe 101. The reducing agent injection unit 12a injects the reducing agent supplied from the reducing agent supply unit 13 via the supply pipe 18 into the exhaust gas, mixing the reducing agent with the exhaust gas. Mixer 12 then sends the exhaust gas mixed with the reducing agent to reactor 11 through the discharge pipe 12b.

[0039] The reducing agent supply unit 13 supplies a reducing agent to the mixer 12. More specifically, as shown in Figure 1, the reducing agent supply unit 13 comprises a reducing agent tank 14, a reducing agent pump 15, and supply pipes 16-18. The reducing agent tank 14 is a tank for storing the reducing agent to be supplied. Examples of this reducing agent include urea solution. As shown in Figure 1, the supply pipes 16-18 are piped to connect the reducing agent tank 14 and the reducing agent injection unit 12a of the mixer 12 via a junction valve 34 and a dosing unit 35. The junction valve 34 and the dosing unit 35 will be described later. The reducing agent pump 15 is installed, for example, in the middle of the supply pipe 16 and pumps the reducing agent from the reducing agent tank 14 to the mixer 12 via the supply pipes 16-18, etc. Due to the action of this reducing agent pump 15, the reducing agent is injected from the reducing agent injection unit 12a inside the mixer 12.

[0040] (Drain treatment device) The drain treatment device 20 is a device for utilizing the ammonia component of ammonia-containing drain discharged from the fuel injection system 3 of a marine diesel engine 1 in one or more functional units. As shown in Figure 1, the drain treatment device 20 comprises a recovery unit 21 for recovering ammonia-containing drain and a supply unit 26 for supplying the ammonia component of the recovered ammonia-containing drain to one or more functional units.

[0041] The recovery unit 21 communicates with the fuel injection system 3 of the marine diesel engine 1 described above and recovers ammonia-containing drain discharged from the fuel injection system 3. More specifically, as shown in Figure 1, the recovery unit 21 comprises at least one recovery pipe through which the mixed drain from the fuel injection system 3 flows, and a recovery tank 25 communicating with the at least one recovery pipe. In this embodiment 1, the at least one recovery pipe includes, for example, a first recovery pipe 22, a second recovery pipe 23, and a third recovery pipe 24. The mixed drain is a drain in which the ammonia fuel is mixed with gaseous components or oily components other than ammonia. Examples of gaseous components other than ammonia include the purge gas described above. Examples of oily components include the fossil fuels described above and the lubricating oil of the ammonia pump 5b.

[0042] The first recovery pipe 22 is an example of at least one of the above-mentioned recovery pipes, and is a pipe for recovering ammonia-containing drain discharged from the fuel injection valve 4 of the fuel injection system 3. In detail, as shown in Figure 1, one end of the first recovery pipe 22 is connected to the fuel injection valve 4 and the other end is connected to the recovery tank 25, thus connecting the fuel injection valve 4 and the recovery tank 25. The first recovery pipe 22 recovers the first mixed drain 201 from the fuel injection valve 4 and circulates the recovered first mixed drain 201 into the recovery tank 25. The first mixed drain 201 is a drain containing a mixture of fossil fuel and ammonia fuel discharged from the fuel injection valve 4.

[0043] The second recovery pipe 23 is an example of at least one of the recovery pipes described above, and is a pipe for recovering ammonia-containing drain discharged from the ammonia pump 5b of the fuel injection system 3. In detail, as shown in Figure 1, one end of the second recovery pipe 23 is connected to the ammonia pump 5b and the other end is connected to the recovery tank 25, thus connecting the ammonia pump 5b and the recovery tank 25. The second recovery pipe 23 recovers the second mixed drain 202 from the ammonia pump 5b and circulates the recovered second mixed drain 202 into the recovery tank 25. The second mixed drain 202 is a drain discharged from the ammonia pump 5b that is a mixture of lubricating oil and ammonia fuel.

[0044] The third recovery pipe 24 is an example of at least one of the recovery pipes described above, and is a pipe for recovering ammonia-containing drain discharged from the purge section 9 of the fuel injection system 3. In detail, as shown in Figure 1, one end of the third recovery pipe 24 is connected to the outlet pipe 9b of the purge section 9 and the other end is connected to the recovery tank 25, thus connecting the outlet pipe 9b and the recovery tank 25. As described above, this outlet pipe 9b is connected to the first inner pipe 7a of the double pipe 7, which is a connecting pipe that connects the fuel injection valve 4 and the ammonia pump 5b. That is, the third recovery pipe 24 connects the first inner pipe 7a and the recovery tank 25 via the outlet pipe 9b. Such a third recovery pipe 24 recovers the third mixed drain 203 from the first inner pipe 7a via the outlet pipe 9b and circulates the recovered third mixed drain 203 into the recovery tank 25. The third mixed drain 203 is a drain containing ammonia fuel and purge gas, discharged from the first inner pipe 7a by the purge section 9.

[0045] The recovery tank 25 recovers mixed drain from the fuel injection system 3 through at least one of the recovery pipes and stores ammonia-containing drain containing at least one gaseous component other than ammonia and an oil component, along with ammonia fuel. Specifically, as shown in Figure 1, the recovery tank 25 is connected to the first recovery pipe 22, the second recovery pipe 23, and the third recovery pipe 24, and recovers the first mixed drain 201, the second mixed drain 202, and the third mixed drain 203 from these recovery pipes, respectively. The recovery tank 25 stores the recovered first mixed drain 201, the second mixed drain 202, and the third mixed drain 203 as ammonia-containing drain 200 from the fuel injection system 3. In this embodiment 1, the ammonia-containing drain 200 contains ammonia fuel, fossil fuel, lubricating oil, and purge gas discharged from the fuel injection system 3.

[0046] Furthermore, the recovery tank 25 also functions as a gas-liquid separator. That is, the recovery tank 25 separates the stored ammonia-containing drain 200 into ammonia-containing liquid 204 and ammonia-containing gas 205. The ammonia-containing liquid 204 is a liquid component containing an oil component which is at least one of the fossil fuel in the first mixed drain 201 and the lubricating oil in the second mixed drain 202, and the recovered ammonia fuel. The ammonia-containing gas 205 is a gaseous component which contains ammonia gas vaporized from the recovered ammonia fuel and the purge gas in the third mixed drain 203.

[0047] The supply unit 26 supplies the ammonia components contained in the ammonia-containing drain 200 recovered by the recovery unit 21 to one or more functional units that utilize the ammonia components. In this embodiment 1, one of the one or more functional units is the exhaust gas treatment device 10 described above. That is, the supply unit 26 supplies the ammonia components contained in the ammonia-containing drain 200 to the exhaust gas treatment device 10. As shown in Figure 1, such a supply unit 26 includes an oxidation reactor 27, a supply pipe 28, and a pump 29 for supplying the ammonia components contained in the ammonia-containing liquid 204 separated from the ammonia-containing drain 200 to the exhaust gas treatment device 10. The supply unit 26 also includes an ammonia water generation unit 30, an introduction pipe 31, a supply pipe 32, a pump 33, and a junction valve 34 for supplying the ammonia components contained in the ammonia-containing gas 205 separated from the ammonia-containing drain 200 to the exhaust gas treatment device 10. Furthermore, the supply unit 26 includes a dosing unit 35, a nitrogen oxide sensor 36, and a control unit 37.

[0048] The oxidation reactor 27 is an example of an extraction unit that removes oil components from the ammonia-containing liquid 204 and extracts the ammonia component. More specifically, as shown in Figure 1, the oxidation reactor 27 is composed of, for example, a catalyst having an oxidizing function and is installed in the middle of the exhaust pipe 101 that connects the marine diesel engine 1 and the mixer 12 of the exhaust gas treatment device 10. More specifically, the exhaust pipe 101 is a pipe that branches into a first branch pipe 101a and a second branch pipe 101b in the middle of its length. One end of the first branch pipe 101a is connected to the marine diesel engine 1 and the other end is connected to the mixer 12, connecting the marine diesel engine 1 and the mixer 12. The second branch pipe 101b branches off from the first branch pipe 101a in the middle of the exhaust pipe 101 and merges with the first branch pipe 101a downstream of the branching point of these branch pipes in the exhaust pipe 101. The oxidation reactor 27 is installed in the middle of the second branch pipe 101b of the exhaust pipe 101 and is configured to allow a portion of the exhaust gas discharged from the marine diesel engine 1 to the exhaust pipe 101 to flow in and out through the second branch pipe 101b.

[0049] As shown in Figure 1, the supply pipe 28 has one end connected to the middle section of the second branch pipe 101b upstream of the oxidation reactor 27, and the other end connected to a section below the liquid level of the ammonia-containing liquid 204 in the recovery tank 25, thus connecting the recovery tank 25 and the oxidation reactor 27 via the second branch pipe 101b. The pump 29 is installed in the middle section of the supply pipe 28 (near the recovery tank 25 in Figure 1). The supply pipe 28, through the action of the pump 29, delivers the ammonia-containing liquid 204 from the recovery tank 25 to the oxidation reactor 27.

[0050] Here, the oxidation reactor 27 receives ammonia-containing liquid 204 supplied through the supply pipe 28 and exhaust gas from the marine diesel engine 1 through the second branch pipe 101b. The oxidation reactor 27 brings the supplied ammonia-containing liquid 204 into contact with an oxidation catalyst layer (not shown) and burns the ammonia-containing liquid 204 by an oxidation reaction using the exhaust gas as a heat source. As a result, in the oxidation reactor 27, the oil component of the ammonia-containing liquid 204 and the ammonia fuel are converted into high-temperature exhaust gas containing nitrogen oxides (NOx, etc.) by combustion, and a portion of the ammonia fuel is oxidized and converted into nitrogen oxides (N2O, etc.) derived from the ammonia fuel. These nitrogen oxides derived from the ammonia fuel are included in the high-temperature exhaust gas along with the NOx. The remaining ammonia fuel is extracted as unburned ammonia components. Subsequently, the oxidation reactor 27 sends the mixed gas 206, which contains these high-temperature exhaust gases (including nitrogen oxides such as NOx and N2O) and unburned ammonia components, to the second branch pipe 101b and combines it with the exhaust gas in the first branch pipe 101a. The supply unit 26 then supplies the unburned ammonia components extracted by the oxidation reactor 27, along with the mixed gas 206 and the high-temperature exhaust gas, to the mixer 12 through the first branch pipe 101a. These unburned ammonia components are used as part of the reducing agent mixed with the exhaust gas by the mixer 12, and the high-temperature exhaust gas is used to promote the vaporization and hydrolysis of the reducing agent injected from the reducing agent injection unit 12a.

[0051] The ammonia water generation unit 30 generates ammonia water from ammonia-containing gas 205. More specifically, as shown in Figure 1, the ammonia water generation unit 30 is connected to an introduction pipe 31 for introducing ammonia-containing gas 205 from the recovery tank 25 to the ammonia water generation unit 30. One end of the introduction pipe 31 is connected above the liquid level of the ammonia-containing liquid 204 in the recovery tank 25, and the other end is connected to the ammonia water generation unit 30, thus connecting the recovery tank 25 and the ammonia water generation unit 30. For example, the ammonia water generation unit 30 has an immersion pipe 30a inside that leads to the introduction pipe 31. The ammonia water generation unit 30 also stores water supplied from a water injection unit (not shown) in advance. The ammonia water generation unit 30 adds water to the ammonia-containing gas 205 by injecting the ammonia-containing gas 205 introduced from the recovery tank 25 through the introduction pipe 31 into the immersion pipe 30a into the water. As a result, the ammonia water generation unit 30 separates the ammonia-containing gas 205 into purge gas and ammonia gas, and generates ammonia water 207, which is an aqueous solution of the ammonia gas. The ammonia water 207 contains ammonia components derived from the ammonia-containing drain 200. The ammonia water generation unit 30 discharges the purge gas separated from the ammonia-containing gas 205 to the outside and sends the generated ammonia water 207 to the supply pipe 32.

[0052] The ammonia water generation unit 30 is not limited to the one equipped with the immersion pipe 30a shown in Figure 1; for example, it may be equipped with a spray nozzle instead of the immersion pipe 30a. In this case, the ammonia water generation unit 30 adds water from the spray nozzle to the ammonia-containing gas 205 introduced through the introduction pipe 31, thereby separating the purge gas from the ammonia-containing gas 205 and generating ammonia water 207 as described above.

[0053] As shown in Figure 1, one end of the supply pipe 32 is connected below the liquid level of the ammonia water 207 in the ammonia water generation unit 30, and the other end is connected to the junction valve 34, connecting the ammonia water generation unit 30 and the reducing agent supply unit 13 (for example, the supply pipe 17) of the exhaust gas treatment device 10 via the junction valve 34. The pump 33 is installed in the middle of the supply pipe 32 (near the ammonia water generation unit 30 in Figure 1). The supply pipe 32 delivers ammonia water 207 from the ammonia water generation unit 30 to the reducing agent supply unit 13 through the action of the pump 33.

[0054] The merging valve 34 is a valve for merging the reducing agent from the reducing agent tank 14 with the ammonia water 207 from the ammonia water generation unit 30. In detail, the merging valve 34 is composed of a solenoid valve or the like and is connected to the supply pipes 16 and 17 on the exhaust gas treatment device 10 side and the supply pipe 32 on the drain treatment device 20 side, for example, as shown in Figure 1. The merging valve 34 merges the reducing agent flowing from the reducing agent tank 14 through the supply pipe 16 with the ammonia water 207 flowing from the ammonia water generation unit 30 through the supply pipe 32 at a desired merging ratio and sends the combined fluid of these reducing agent and ammonia water 207 to the supply pipe 17.

[0055] Furthermore, the merging valve 34 allows for adjustment of the valve opening on the supply pipe 16 side and the valve opening on the supply pipe 32 side, respectively. By adjusting these valve openings, the mixing ratio of the reducing agent and the ammonia water 207 can be adjusted. For example, this mixing ratio can be adjusted in percentage terms within the range of reducing agent:ammonia water 207 = 100:0 to 0:100. That is, the reducing agent supplied from the merging valve 34 to the mixer 12 through the supply pipes 17 and 18 is either the reducing agent from the reducing agent tank 14, the ammonia water 207 from the ammonia water generation unit 30, or a combined fluid of these reducing agents and ammonia water 207. Hereinafter, in order to distinguish between the reducing agent supplied to the mixer 12 (including the above combined fluid) and the reducing agent from the reducing agent tank 14 (that has not been mixed with ammonia water 207), the reducing agent from the reducing agent tank 14 may be referred to as the main reducing agent.

[0056] The dosing unit 35 adjusts the flow rate of the reducing agent supplied from the reducing agent supply unit 13 to the mixer 12. More specifically, as shown in Figure 1, the dosing unit 35 is installed between the supply pipes 17 and 18 of the exhaust gas treatment device 10. The dosing unit 35 adjusts the flow rate of the reducing agent whose merging ratio has been adjusted by the merging valve 34, and supplies the reduced agent with the adjusted flow rate to the mixer 12 through the supply pipe 18.

[0057] The nitrogen oxide sensor detects the nitrogen oxide content (amount of nitrogen oxides) in the exhaust gas after treatment by the exhaust gas treatment device 10. Specifically, as shown in Figure 1, the nitrogen oxide sensor 36 is installed in the exhaust pipe 19 of the exhaust gas treatment device 10. The nitrogen oxide sensor 36 detects the nitrogen oxide content in the exhaust gas flowing inside the exhaust pipe 19 and transmits a signal indicating the detected nitrogen oxide content to the control unit 37.

[0058] The control unit 37 controls the mixing ratio of the main reducing agent and ammonia water 207 and the flow rate of the reducing agent according to the nitrogen oxide content in the exhaust gas after treatment by the exhaust gas treatment device 10. Specifically, as shown in Figure 1, the control unit 37 is provided, for example, in the exhaust gas treatment device 10 and is connected to each of the mixing valve 34, the dosing unit 35, and the nitrogen oxide sensor 36 so as to be able to send and receive signals. The control unit 37 receives a signal from the nitrogen oxide sensor 36 and obtains the nitrogen oxide content detected by the nitrogen oxide sensor 36 based on the received signal. The control unit 37 controls the valve opening of the mixing valve 34 and the operation of the dosing unit 35 according to the obtained nitrogen oxide content. In this way, the control unit 37 controls the mixing ratio and flow rate of the reducing agent supplied to the mixer 12. For example, the control unit 37 increases at least one of the mixing ratio of the main reducing agent to ammonia water 207 and the flow rate of the reducing agent in response to an increase in the nitrogen oxide content. Furthermore, the control unit 37 reduces at least one of the following in accordance with the decrease in nitrogen oxide content: the mixing ratio of the main reducing agent to the ammonia water 207 and the flow rate of the reducing agent.

[0059] Here, the supply unit 26 supplies ammonia water 207 to the reducing agent supply unit 13 via the supply pipe 32 and the junction valve 34 described above, thereby adding ammonia water 207 to the reducing agent supplied from the reducing agent supply unit 13 to the mixer 12. At this time, the ammonia water 207 is injected into the exhaust gas in the mixer 12 from the reducing agent injection unit 12a as at least a portion of the reducing agent, and is mixed with the exhaust gas together with the unburned ammonia component from the oxidation reactor 27 described above. Subsequently, nitrogen oxides in the exhaust gas supplied from the mixer 12 to the reactor 11 are denitrified by the reactor 11 as described above. In this embodiment 1, the ammonia component in ammonia water 207 is thus used as a reducing agent to reduce the amount of nitrogen oxides emitted from the exhaust gas.

[0060] As described above, in the drain treatment device 20 according to Embodiment 1 of the present invention, ammonia-containing drain 200 discharged from the fuel injection system 3 of the marine diesel engine 1 is recovered by the recovery unit 21, and the ammonia components contained in the recovered ammonia-containing drain 200 are supplied by the supply unit 26 to one or more functional units that function using the ammonia components. Specifically, ammonia-containing drain 200, which is a mixture of ammonia fuel, fossil fuel, lubricating oil, and purge gas discharged from the fuel injection system 3, is recovered and stored in the recovery tank 25, and the stored ammonia-containing drain 200 is separated into ammonia-containing liquid 204 and ammonia-containing gas 205 by the recovery tank 25, and the ammonia components extracted from the ammonia-containing liquid 204 by the oxidation reactor 27 and ammonia water 207 produced by adding water to the ammonia-containing gas 205 are supplied to the exhaust gas treatment device 10, which is one of the one or more functional units.

[0061] Therefore, the purge gas (a harmless gas such as nitrogen gas) separated from the ammonia-containing gas 205 can be easily discharged, and the ammonia components in the ammonia-containing liquid 204 and the ammonia-containing gas 205 can be effectively utilized as reducing agents for denitrification of nitrogen oxides in the exhaust gas in the exhaust gas treatment device 10 without increasing the amount of nitrogen oxides discharged from the ship by incineration. Furthermore, there is no need to store the ammonia-containing drain 200 on board the ship until it is unloaded, and the oil components contained in the ammonia-containing liquid 204 can be converted into nitrogen oxides by the oxidation reactor 27 and efficiently treated by the exhaust gas treatment device 10, which effectively utilizes the ammonia components as a reducing agent. Thus, the cost required for treating the ammonia-containing drain 200 can be reduced.

[0062] Furthermore, in the drain treatment device 20 according to Embodiment 1 of the present invention, ammonia water 207, generated from the gaseous component (ammonia-containing gas 205) of the ammonia-containing drain 200, is additionally supplied to the exhaust gas treatment device 10 as a reducing agent to be mixed with the exhaust gas in the mixer 12. As a result, the amount of main reducing agent consumed from the reducing agent tank 14, which is normally used in the exhaust gas treatment device 10, can be reduced by the amount of the additional supply of ammonia water 207, thereby saving the main reducing agent.

[0063] Furthermore, in the drain treatment device 20 according to Embodiment 1 of the present invention, the ammonia component extracted from the liquid component (ammonia-containing liquid 204) of the ammonia-containing drain 200 is supplied to the mixer 12 of the exhaust gas treatment device 10 together with the exhaust gas. As a result, the ammonia concentration in the reducing agent mixed with the exhaust gas in the mixer 12 can be increased, thereby enhancing the denitrification effect of nitrogen oxides in the exhaust gas by the reactor 11 of the exhaust gas treatment device 10.

[0064] (Embodiment 2) Next, a drain treatment device according to Embodiment 2 of the present invention will be described. Figure 2 is a diagram showing an example configuration of a drain treatment device according to Embodiment 2 of the present invention. In addition to the drain treatment device 20A according to Embodiment 2, Figure 2 shows a marine diesel engine 1 to which this drain treatment device 20A is applied, and an EGR device 40, which is an exhaust gas recirculation (EGR) device applied to this marine diesel engine 1.

[0065] As shown in Figure 2, the drain treatment device 20A includes a recovery unit 21A in place of the recovery unit 21 of the drain treatment device 20 according to Embodiment 1 described above, and a supply unit 26A in place of the supply unit 26. In this Embodiment 2, an EGR device 40 is provided in place of the exhaust gas treatment device 10 in Embodiment 1 described above, as a device for reducing nitrogen oxides in the exhaust gas of the marine diesel engine 1. The other configurations are the same as in Embodiment 1, and the same components are denoted by the same reference numerals. In the marine diesel engine 1 shown in Figure 2, for the sake of explanation, a ventilation system 60 for ventilating the internal space of the double pipe 7 is shown, and the illustration of the purge unit 9 described above is omitted. The ventilation system 60 and the EGR device 40 of the marine diesel engine 1 will be described in order below, and then the drain treatment device 20A will be described.

[0066] (Ventilation system for marine diesel engines) As shown in Figure 2, the ventilation system 60 of the marine diesel engine 1 includes a ventilation fan 61, a ventilation pipe 62, an ammonia sensor 63, a spray nozzle 64, and a control unit 65.

[0067] The ventilation fan 61 draws in gas from the internal space of the double-walled pipe 7 in order to ventilate the internal space of the double-walled pipe 7. As shown in Figure 2, the ventilation fan 61 is installed in the middle of the ventilation pipe 62. As shown in Figure 2, the ventilation pipe 62 is piped in the middle of the second outer pipe 7d of the double-walled pipe 7, for example, near the ammonia fuel tank 8. The ventilation pipe 62 communicates with the internal space of the double-walled pipe 7 and discharges the gas (air) drawn in by the ventilation fan 61 to the outside. The internal space of the double-walled pipe 7 refers to the space between the outer surface of the first inner pipe 7a and the inner surface of the first outer pipe 7b, and the space between the outer surface of the second inner pipe 7c and the inner surface of the second outer pipe 7d. In addition, although not specifically shown, the double-walled pipe 7 is provided with a ventilation opening that sends outside air into the internal space of the double-walled pipe 7 when gas is drawn in by the ventilation fan 61. This ventilation opening, for example, has a check valve structure that allows outside air to be supplied to the internal space and prevents gas from flowing out of the internal space to the outside.

[0068] As shown in Figure 2, the ammonia sensor 63 is installed in the middle of the second outer pipe 7d of the double pipe 7 and detects ammonia gas present in the internal space of the double pipe 7. More specifically, the ammonia sensor 63 detects ammonia components if they are present in the internal gas 210 drawn in by the ventilation fan 61. The internal gas 210 is the gas present in the internal space of the double pipe 7. The ammonia sensor 63 transmits a signal to the control unit 65 indicating the detection result of the ammonia components (presence or absence of ammonia components).

[0069] As shown in Figure 2, the fountain unit 64 has a fountain nozzle 64a and is installed between the ventilation pipe 62 and the ammonia sensor 63 (i.e., on the ammonia fuel tank 8 side of the ammonia sensor 63) with the nozzle opening of the fountain nozzle 64a facing the internal space of the double pipe 7. The fountain unit 64 sprays water from the fountain nozzle 64a onto the internal gas 210 that is drawn in by the ventilation fan 61. In this way, the fountain unit 64 removes ammonia components from the internal gas 210 and generates ammonia water by mixing the removed ammonia components with water. The internal gas 210 after the removal of ammonia components is, for example, air, and is discharged to the outside from the internal space of the double pipe 7 through the ventilation pipe 62 by the action of the ventilation fan 61.

[0070] As shown in Figure 2, the control unit 65 is connected to the ammonia sensor 63 and the water fountain unit 64, respectively, to enable the transmission and reception of signals. The control unit 65 receives a signal from the ammonia sensor 63 and, based on the received signal, determines whether or not the internal gas 210 contains ammonia. If the internal gas 210 contains ammonia, the control unit 65 controls the water fountain unit 64 to spray water towards the internal gas 210. If the internal gas 210 does not contain ammonia, the control unit 65 controls the water fountain unit 64 to stop spraying water towards the internal gas 210.

[0071] (EGR device) The EGR system 40 is a device that reduces nitrogen oxides in the exhaust gas by cleaning the recirculated gas, which is a portion of the exhaust gas discharged from the marine diesel engine 1, with scrubber water and returning it to the marine diesel engine 1. For example, as shown in Figure 2, the EGR system 40 includes a scrubber 41, a demister 42, and an EGR blower 43. The EGR system 40 also includes a collecting tank 44, an alkaline liquid supply unit 45a, a fresh water supply unit 45b, a pH meter 46, a control unit 47, a water supply pipe 48, and a pump 49.

[0072] The scrubber 41 cleans a portion of the exhaust gas discharged from the marine diesel engine 1 for use as recirculated gas (reuse). As shown in Figure 2, an inlet circulation pipe 103 is connected to the inlet of the scrubber 41. The inlet circulation pipe 103 is connected to the middle section of the exhaust pipe 102 that leads to the marine diesel engine 1. A portion of the exhaust gas from the marine diesel engine 1 is supplied to the scrubber 41 through the exhaust pipe 102 and the inlet circulation pipe 103. The remaining exhaust gas is discharged to the outside through the ship's chimney via the exhaust pipe 102. The scrubber 41 is equipped with a scrubber water injection unit 41a that sprays scrubber water onto the exhaust gas to be cleaned. The scrubber water injection unit 41a has an injection nozzle that faces inward into the scrubber 41 and is configured to supply scrubber water through piping. The scrubber 41 sprays scrubber water from the scrubber water injection unit 41a onto the exhaust gas (recirculated gas) supplied through the inlet circulation pipe 103, thereby cleaning the recirculated gas.

[0073] As shown in Figure 2, the demister 42 is a hollow rectangular housing connected to the outlet of the scrubber 41. An outlet pipe 42a leading to the collecting tank 44 is connected to the bottom of the demister 42. Recirculated gas cleaned by the spray of scrubber water in the scrubber 41 and scrubber water used to clean this recirculated gas flow into the demister 42. The demister 42 separates the cleaned recirculated gas from the used scrubber water. Of these recirculated gas and scrubber water, the recirculated gas is sent from the gas outlet of the demister 42 to the EGR blower 43, and the scrubber water is recovered from the bottom of the demister 42 through the outlet pipe 42a to the collecting tank 44.

[0074] As shown in Figure 2, the EGR blower 43 is installed on top of the demister 42. A return outlet pipe 104, which leads to the marine diesel engine 1, is connected to the outlet of the EGR blower 43. The EGR blower 43 supplies the recirculated gas discharged from the demister 42 to the marine diesel engine 1 through the return outlet pipe 104.

[0075] The collecting tank 44 is positioned below the demister 42, as shown in Figure 2, for example, and is connected to the demister 42 via an outlet pipe 42a. The collecting tank 44 recovers the scrubber water 208 used for cleaning the exhaust gas as described above from the demister 42 through the outlet pipe 42a and stores the recovered scrubber water 208. The recovered scrubber water 208 is acidic because it contains sulfur oxides (SOx) and other substances removed from the exhaust gas by cleaning.

[0076] As shown in Figure 2, the alkaline solution supply unit 45a is connected to the collecting tank 44 through piping and supplies an alkaline solution to the collecting tank 44 for neutralizing the scrubber water 208 by the action of a pump or the like (not shown). Examples of the alkaline solution include sodium hydroxide. The collecting tank 44 stores the acidic scrubber water 208 as described above and neutralizes the scrubber water 208 with the alkaline solution supplied from the alkaline solution supply unit 45a or the like.

[0077] As shown in Figure 2, the freshwater supply unit 45b communicates with the collecting tank 44 through piping and supplies freshwater to the collecting tank 44 for diluting or replenishing the scrubber water 208 through the action of a pump or the like (not shown). Examples of this freshwater include freshwater loaded from outside the ship, freshwater produced on board the ship, and drain water discharged from the marine diesel engine 1.

[0078] As shown in Figure 2, the pH meter 46 is installed in the collecting tank 44 and measures the pH of the scrubber water 208. The pH meter 46 transmits a signal indicating the measured pH (measured value) of the scrubber water 208 to the control unit 47.

[0079] The control unit 47 obtains the pH of the scrubber water 208 based on the signal received from the pH meter 46, and controls the amount of alkaline solution supplied from the alkaline solution supply unit 45a to the collecting tank 44 based on the obtained pH. The control unit 47 also controls the amount of clean water supplied from the clean water supply unit 45b to the collecting tank 44 based on the liquid level of the scrubber water 208 in the collecting tank 44.

[0080] The water supply pipe 48 and pump 49 are for supplying the neutralized scrubber water 208 to the scrubber 41. As shown in Figure 2, the water supply pipe 48 is routed to connect the scrubber water injection section 41a of the scrubber 41 with the collecting tank 44. The pump 49 is located midway along the water supply pipe 48. The water supply pipe 48 supplies the neutralized scrubber water 208 to the scrubber water injection section 41a through the action of the pump 49. This scrubber water 208 is reused for cleaning exhaust gas by the scrubber 41.

[0081] As shown in Figure 2, the water treatment device 50 is installed in the middle of the water supply pipe 48 and removes foreign matter (for example, soot from exhaust gas) from the scrubber water 208 supplied to the scrubber 41 through the water supply pipe 48. The water treatment device 50 returns the scrubber water 208, from which the foreign matter has been removed, to the water supply pipe 48.

[0082] (Drain treatment device) As shown in Figure 2, the drain treatment device 20A includes a recovery unit 21A for recovering ammonia-containing drain 200A and a supply unit 26A for supplying the ammonia component of the recovered ammonia-containing drain to one or more functional units.

[0083] The recovery unit 21A communicates with the fuel injection system 3 of the marine diesel engine 1 described above and recovers the ammonia-containing drain 200A discharged from this fuel injection system 3. In detail, as shown in Figure 2, the recovery unit 21A is a hollow structure and is configured to airtightly cover the ammonia pump 5b and communicate with the double pipe 7. Specifically, the recovery unit 21A is airtightly connected to the first outer pipe 7b and the second outer pipe 7d of the double pipe 7 and has a bottomed space that connects the internal space between the outer surface of the first inner pipe 7a and the inner surface of the first outer pipe 7b, and the internal space between the outer surface of the second inner pipe 7c and the inner surface of the second outer pipe 7d, and airtightly covers the ammonia pump 5b inside this bottomed space.

[0084] Here, as shown in Figure 2, the second outer pipe 7d of the double pipe 7, together with the second inner pipe 7c, slopes downward from the ammonia fuel tank 8 towards the ammonia pump 5b. Furthermore, the ammonia components separated from the internal gas 210 of the double pipe 7 by the spray nozzle 64 of the ventilation system 60 described above dissolve in the water sprayed from the spray nozzle 64 to form ammonia water. This ammonia water flows down along the inner surface of the second outer pipe 7d and is poured into the bottomed space of the recovery unit 21A. The recovery unit 21A recovers this ammonia water from the double pipe 7 as ammonia-containing drain 200A. The recovery unit 21A stores the recovered ammonia-containing drain 200 at the bottom of its bottomed space.

[0085] The supply unit 26A supplies the ammonia component contained in the ammonia-containing drain 200A recovered by the recovery unit 21A described above to one or more functional units that function using the ammonia component. In this embodiment 2, one of the one or more functional units is the collecting tank 44 of the EGR device 40 described above. As shown in Figure 2, the supply unit 26A is composed of piping that slopes downward from the recovery unit 21A toward the collecting tank 44, and connects the recovery unit 21A and the collecting tank 44. The supply unit 26A uses gravity to supply the ammonia-containing drain 200A from the recovery unit 21A to the collecting tank 44.

[0086] Here, the ammonia-containing drain 200A is ammonia water containing ammonia components derived from ammonia fuel, and therefore functions as an alkaline solution to neutralize the acidic scrubber water 208. The supply unit 26A supplies this ammonia-containing drain 200A to the collecting tank 44 separately from the alkaline solution supply unit 45a mentioned above. The collecting tank 44 mixes the alkaline solution from the alkaline solution supply unit 45a and the ammonia-containing drain 200A from the supply unit 26A with the acidic scrubber water 208, thereby neutralizing the scrubber water 208. In this embodiment 2, the ammonia components of the ammonia-containing drain 200A are thus used as an alkaline component to neutralize the acidic scrubber water 208.

[0087] As described above, in the drain treatment device 20A according to Embodiment 2 of the present invention, ammonia-containing drain 200A discharged from the fuel injection system 3 of the marine diesel engine 1 is recovered by the recovery unit 21A, and the ammonia component contained in the recovered ammonia-containing drain 200A is supplied by the supply unit 26A to one or more functional units that function using the ammonia component. Specifically, ammonia-containing drain 200A, which is ammonia water, is recovered from the internal space of the double pipe 7 of the fuel injection system 3 into the bottomed space of the recovery unit 21A and stored, and the stored ammonia-containing drain 200A is supplied by the supply unit 26A to the collecting tank 44 of the EGR device 40, which is one of the one or more functional units.

[0088] Therefore, the ammonia component of the ammonia-containing drain 200A can be effectively utilized as an alkaline component (alkaline solution) to neutralize the acidic scrubber water 208 in the collecting tank 44, without incinerating it and increasing the amount of nitrogen oxides discharged from the ship. Furthermore, there is no need to store the ammonia-containing drain 200A on board the ship until it is unloaded, and thus the cost required for treating the ammonia-containing drain 200A can be reduced.

[0089] Furthermore, in the drain treatment apparatus 20A according to Embodiment 2 of the present invention, in addition to the alkaline liquid supply unit 45a that normally supplies alkaline liquid to the collecting tank 44, ammonia-containing drain 200A (ammonia water) is also supplied from the supply unit 26A. Therefore, the neutralization treatment of scrubber water 208 in the collecting tank 44 is supported by the supply of ammonia-containing drain 200A, and the amount of alkaline liquid consumed from the alkaline liquid supply unit 45a can be reduced by the amount of the additional supply of ammonia-containing drain 200A, thereby saving the alkaline liquid.

[0090] (Embodiment 3) Next, a drain treatment device according to Embodiment 3 of the present invention will be described. Figure 3 is a diagram showing an example configuration of a drain treatment device according to Embodiment 3 of the present invention. In addition to the drain treatment device 20B according to Embodiment 3, Figure 3 shows a marine diesel engine 1 to which this drain treatment device 20B is applied, and an exhaust gas treatment device 10 applied to this marine diesel engine 1. As shown in Figure 3, the drain treatment device 20B is equipped with a supply unit 26B in place of the supply unit 26 of the drain treatment device 20 according to Embodiment 1 described above. Furthermore, in Embodiment 3, the exhaust gas treatment device 10 is equipped with a supply pipe 16A in place of the supply pipes 16 and 17 in Embodiment 1 described above, a dosing unit 35A in place of the dosing unit 35, and a control unit 37A in place of the control unit 37. The other configurations are the same as in Embodiment 1, and the same reference numerals are used for the same components.

[0091] (Drain treatment device) The drain treatment device 20B supplies the ammonia component contained in the liquid component (ammonia-containing liquid 204) of the ammonia-containing drain 200 to the exhaust gas treatment device 10 in the same manner as in Embodiment 1 described above, and also supplies the ammonia component contained in the gaseous component (ammonia-containing gas 205) of the ammonia-containing drain 200 to the combustion chamber 2c of the marine diesel engine 1. In other words, in this Embodiment 3, the one or more functional units that utilize the ammonia component are the drive system 2 of the marine diesel engine 1 and the exhaust gas treatment device 10.

[0092] As shown in Figure 3, the supply unit 26B of such a drain treatment device 20B includes an oxidation reactor 27, a supply pipe 28, and a pump 29 for supplying ammonia components contained in ammonia-containing liquid 204 to the exhaust gas treatment device 10. These oxidation reactor 27, supply pipe 28, and pump 29 are the same as those in Embodiment 1 described above. The supply unit 26B also includes an ammonia water generation unit 30, an introduction pipe 31, supply pipes 32A-1 and 32A-2, a pump 33, an ammonia pump 33A, and an ammonia injection valve 70 for supplying ammonia components contained in ammonia-containing gas 205 to the drive system 2 of the marine diesel engine 1, as shown in Figure 3. Of these, the ammonia water generation unit 30, the introduction pipe 31, and the pump 33 are the same as those in Embodiment 1 described above.

[0093] As shown in Figure 3, the supply pipe 32A-1 is a pipe in which one end is connected below the liquid level of the ammonia water 207 in the ammonia water generation unit 30 and the other end is connected to the ammonia injection valve 70. An ammonia pump 33A is provided in the middle of this supply pipe 32A-1, as shown in Figure 3. The ammonia pump 33A has a fluid pumping function, similar to the ammonia pump 5b in the fuel injection system 3 of the marine diesel engine 1. The supply pipe 32A-1 connects the ammonia water generation unit 30 and the ammonia injection valve 70 via this ammonia pump 33A. In addition, a pump 33 is provided in the middle of this supply pipe 32A-1 on the ammonia water generation unit 30 side of the ammonia pump 33A, similar to Embodiment 1. The supply pipe 32A-1 supplies ammonia water 207 from the ammonia water generation unit 30 to the ammonia pump 33A through the action of the pump 33. The ammonia pump 33A increases the pressure of the supplied ammonia water 207 and sends it to the outlet side (ammonia injection valve 70 side) of the supply pipe 32A-1. Due to the action of the ammonia pump 33A, the supply pipe 32A-1 pressurizes the ammonia water 207 and sends it to the ammonia injection valve 70.

[0094] As shown in Figure 3, the ammonia injection valve 70 is installed on the cylinder 2a of the drive system 2 with its nozzle facing into the combustion chamber 2c of the marine diesel engine 1. Although not specifically shown, the ammonia injection valve 70 has an internal path leading to the nozzle. The supply unit 26B pumps ammonia water 207 from the ammonia water generation unit 30 through the supply pipe 32A-1, etc., to the ammonia injection valve 70, and injects it into the combustion chamber 2c from the ammonia injection valve 70.

[0095] Furthermore, the above-mentioned supply pipe 32A-1 is provided with a supply pipe 32A-2 for supplying ammonia water 207 to the combustion chamber 2c via the fuel injection system 3 of the marine diesel engine 1. As shown in Figure 3, the supply pipe 32A-2 is a pipe in which one end is connected to the middle part of the supply pipe 32A-1 (for example, the part between the pump 33 and the ammonia pump 33A) and the other end is connected to the ammonia pump 5b of the fuel injection system 3. The supply pipe 32A-2 may also be connected to the second inner pipe 7c of the double pipe 7 that leads to the ammonia pump 5b, and communicate with the ammonia pump 5b via this second inner pipe 7c. The supply pipe 32A-2 supplies ammonia water 207 from the ammonia water generation unit 30 to the ammonia pump 5b by the action of the pump 33, and the ammonia pump 5b pressurizes the ammonia water 207 to the fuel injection valve 4 by the action of the ammonia pump 5b. In other words, the supply unit 26B injects the ammonia water 207 supplied from the ammonia water generation unit 30 to the ammonia pump 5b via the supply pipe 32A-2, etc., into the combustion chamber 2c from the fuel injection valve 4 using the pumping function of the ammonia pump 5b.

[0096] Here, the ammonia water 207 injected into the combustion chamber 2c from the ammonia injection valve 70 as described above is burned (co-combusted) in the combustion chamber 2c together with the ammonia water 207 injected into the combustion chamber 2c from the fuel injection valve 4, ammonia fuel, and fossil fuel. The drive system 2 generates driving force using the combustion energy generated by this. In this embodiment 3, the ammonia component in the ammonia water 207 is thus used as part of the ammonia fuel to drive the drive system 2.

[0097] In the reducing agent supply unit 13 of the exhaust gas treatment device 10 of this third embodiment, the supply pipe 16A is piped to connect the reducing agent tank 14 and the dosing unit 35A, as shown in Figure 3. The dosing unit 35A adjusts the flow rate of the reducing agent supplied from the reducing agent tank 14 to the mixer 12. The control unit 37A controls the dosing unit 35A. The control of the dosing unit 35A by the control unit 37A is the same as in the first embodiment described above.

[0098] As described above, in the drain treatment device 20B according to Embodiment 3 of the present invention, ammonia water 207 generated from the gaseous component (ammonia-containing gas 205) of the recovered ammonia-containing drain 200 is injected into the combustion chamber 2c of the drive system 2 of the marine diesel engine 1, which is one of one or more functional parts that function using the ammonia component, and the rest is the same as in Embodiment 1. Therefore, the same effects as in Embodiment 1 described above can be enjoyed, and the amount of ammonia fuel injected from the fuel injection valve 4 to the combustion chamber 2c can be reduced by the amount of ammonia water 207 injected into the combustion chamber 2c, thereby reducing the consumption of the ammonia fuel.

[0099] (Embodiment 4) Next, a drain treatment device according to Embodiment 4 of the present invention will be described. Figure 4 is a diagram showing an example configuration of a drain treatment device according to Embodiment 4 of the present invention. In addition to the drain treatment device 20C according to Embodiment 4, Figure 4 shows a marine diesel engine 1 to which this drain treatment device 20C is applied, and an EGR device 40 applied to this marine diesel engine 1. As shown in Figure 4, the drain treatment device 20C is equipped with a supply unit 26C in place of the supply unit 26A of the drain treatment device 20A according to Embodiment 2 described above. The other configurations are the same as in Embodiment 2, and the same reference numerals are used for the same components.

[0100] (Drain treatment device) The drain treatment device 20C, instead of supplying the ammonia-containing drain 200A (ammonia water) recovered from the double pipe 7 of the fuel injection system 3 by the recovery unit 21A to the collecting tank 44 of the EGR device 40, supplies (injects) it to the combustion chamber 2c of the marine diesel engine 1, similar to Embodiment 3 described above. In other words, in this Embodiment 4, one of the one or more functional units that utilize the ammonia component is the drive system 2 of the marine diesel engine 1.

[0101] As shown in Figure 4, the supply unit 26C of such a drain treatment device 20C includes supply pipes 32B-1 and 32B-2, a pump 33, an ammonia pump 33A, and an ammonia injection valve 70. Of these, the pump 33, the ammonia pump 33A, and the ammonia injection valve 70 are the same as those in the embodiment 3 described above.

[0102] As shown in Figure 4, the supply pipe 32B-1 is a pipe with one end connected to the bottom of the recovery unit 21A and the other end connected to the ammonia injection valve 70. An ammonia pump 33A is provided in the middle of the supply pipe 32B-1, as shown in Figure 4, and the recovery unit 21A and the ammonia injection valve 70 are connected via the ammonia pump 33A. In addition, a pump 33 is provided in the middle of the supply pipe 32B-1 on the recovery unit 21A side of the ammonia pump 33A, as shown in Figure 4. Through the action of the pump 33, the supply pipe 32B-1 supplies ammonia-containing drain 200A (i.e., ammonia water) from the recovery unit 21A to the ammonia pump 33A, and the ammonia-containing drain 200A, after being pressurized by the ammonia pump 33A, is then pumped to the ammonia injection valve 70. The supply unit 26C injects the ammonia-containing drain 200A, which has been pressurized from the recovery unit 21A through the supply pipe 32B-1 etc. to the ammonia injection valve 70, into the combustion chamber 2c from the ammonia injection valve 70.

[0103] Furthermore, the supply pipe 32B-1 described above is provided with a supply pipe 32B-2 for supplying ammonia-containing drain 200A to the combustion chamber 2c via the fuel injection system 3 of the marine diesel engine 1. As shown in Figure 4, the supply pipe 32B-2 is a pipe in which one end is connected to the middle part of the supply pipe 32B-1 (for example, the part between the pump 33 and the ammonia pump 33A) and the other end is connected to the ammonia pump 5b of the fuel injection system 3. The supply pipe 32B-2 may also be connected to the second inner pipe 7c of the double pipe 7 that leads to the ammonia pump 5b, and communicate with the ammonia pump 5b via this second inner pipe 7c. The supply pipe 32B-2 supplies ammonia-containing drain 200A from the recovery unit 21A to the ammonia pump 5b by the action of the pump 33, and the ammonia pump 5b pressurizes the ammonia-containing drain 200A to the fuel injection valve 4 by the action of the ammonia pump 5b. In other words, the supply unit 26C injects the ammonia-containing drain 200A, which has been supplied from the recovery unit 21A to the ammonia pump 5b via the supply pipe 32B-2, etc., into the combustion chamber 2c from the fuel injection valve 4 using the pumping function of the ammonia pump 5b.

[0104] As described above, the ammonia-containing drain 200A injected into the combustion chamber 2c is used as part of the ammonia fuel to drive the drive system 2, similar to the ammonia water 207 in Embodiment 3 described above.

[0105] As described above, in the drain treatment device 20C according to Embodiment 4 of the present invention, the recovered ammonia-containing drain 200A (ammonia water) is injected into the combustion chamber 2c of the drive system 2 of the marine diesel engine 1, which is one or more functional parts that utilize ammonia components, in the same manner as in Embodiment 3. Therefore, even in a marine diesel engine 1 to which the EGR device 40 is applied, fossil fuel, ammonia fuel, and ammonia-containing drain 200A can be injected into the combustion chamber 2c, thereby reducing the amount of ammonia fuel injected from the fuel injection valve 4 to the combustion chamber 2c by the amount of ammonia-containing drain 200A injected into the combustion chamber 2c. As a result, the consumption of ammonia fuel can be reduced.

[0106] In the embodiments 1 and 3 described above, an ammonia water generation unit 30 was illustrated in which a separation unit that separates ammonia-containing gas 205 into purge gas and ammonia water 207 by adding water and a storage unit that stores the ammonia water 207 are integrated. However, the present invention is not limited thereto. For example, the ammonia water generation unit 30 may be configured with the separation unit and the storage unit as separate components.

[0107] Furthermore, in embodiments 1 and 3 described above, an oxidation reactor 27 was exemplified as an example of an extraction unit for extracting ammonia components from the ammonia-containing liquid 204, but the present invention is not limited thereto. For example, the extraction unit may extract the ammonia components from the ammonia-containing liquid 204 by removing oil components from the ammonia-containing liquid 204 using a filter or the like.

[0108] Furthermore, in embodiments 1 and 3 described above, the first recovery pipe 22, the second recovery pipe 23, and the third recovery pipe 24 were exemplified as at least one recovery pipe for circulating mixed drain from the fuel injection system 3 to the recovery tank 25, but the present invention is not limited thereto. For example, the at least one recovery pipe may be any one of the first recovery pipe 22, the second recovery pipe 23, or the third recovery pipe 24, or it may be two or more selected from the first recovery pipe 22, the second recovery pipe 23, and the third recovery pipe 24.

[0109] Furthermore, while embodiments 1 and 3 described above illustrate an exhaust gas treatment device 10 that denitrifies nitrogen oxides in exhaust gas discharged from a marine diesel engine 1, which is the main engine of a ship, the present invention is not limited thereto. For example, the exhaust gas treatment device 10 may denitrify nitrogen oxides in exhaust gas discharged from auxiliary equipment such as a ship's generator. In this case, the drain treatment devices 20 and 20B may recover ammonia-containing drain from the fuel injection system 3 of the marine diesel engine 1 to which the EGR device 40 illustrated in embodiments 2 and 4 is applied, and the ammonia component of the recovered ammonia-containing drain may be supplied to two or more selected from the exhaust gas treatment device 10, the EGR device 40, and the drive system 2 of the marine diesel engine 1.

[0110] Furthermore, while the above-described embodiment 2 illustrates a supply unit 26A that uses gravity to supply ammonia-containing drain 200A from the recovery unit 21A to the collecting tank 44, the present invention is not limited thereto. For example, the supply unit 26A may include a supply pipe connecting the recovery unit 21A and the collecting tank 44, and a pump that pumps the ammonia-containing drain 200A from the recovery unit 21A to the collecting tank 44 through this supply pipe.

[0111] Furthermore, in embodiments 2 and 4 described above, the ammonia-containing drain 200A recovered from the double pipe 7 of the fuel injection system 3 of the marine diesel engine 1 was supplied to either the collecting tank 44 of the EGR device 40 or the combustion chamber 2c of the marine diesel engine 1. However, the present invention is not limited thereto. For example, the drain treatment devices 20A and 20C may supply the ammonia-containing drain 200A to both the collecting tank 44 of the EGR device 40 and the combustion chamber 2c of the marine diesel engine 1.

[0112] In the embodiments 1 to 4 described above, the exhaust gas treatment device 10, the collecting tank 44 of the EGR device 40, and the drive system 2 of the marine diesel engine 1 were given as examples of one or more functional parts that function using ammonia components, but the present invention is not limited thereto. For example, the one or more functional parts may be the exhaust gas treatment device 10, the collecting tank 44 of the EGR device 40, the drive system 2 of the marine diesel engine 1, other onboard equipment (auxiliary equipment such as a generator), or two or more selected from among these.

[0113] Furthermore, the present invention is not limited to the embodiments 1 to 4 described above, and configurations that appropriately combine the above-described components are also included in the present invention. In addition, all other embodiments, examples, and operational techniques made by those skilled in the art based on the embodiments 1 to 4 described above are also included in the scope of the present invention. [Explanation of Symbols]

[0114] 1. Marine diesel engine 2. Drive System 2a Cylinder 2b Piston 2c Combustion chamber 2d Exhaust valve 3 Fuel injection system 4. Fuel Injector 5a Fuel pump 5b Ammonia pump 6 Communication pipe 7 double tube 7a 1st inner tube 7b 1st outer tube 7c 2nd inner tube 7d 2nd outer tube 8. Ammonia fuel tank 9. Purge section 9a Purge gas inlet 9b Outlet pipe 9c Shut-off valve 10 Exhaust gas treatment equipment 11 Reactor 12 Mixer 12a Reducing agent injection unit 12b Delivery pipe 13. Reducing agent supply unit 14 Reducing agent tank 15. Reducing agent pump 16, 16A, 17, 18 Supply pipe 19 Exhaust pipe 20, 20A, 20B, 20C Drain treatment device 21, 21A Recovery section 22 First recovery pipe 23 Second recovery pipe 24 Third recovery pipe 25 Recovery Tanks 26, 26A, 26B, 26C supply section 27 Oxidation reactor 28 Supply pipe 29 pumps 30 Ammonia water generation unit 30a dip tube 31 Introductory tube 32, 32A-1, 32A-2, 32B-1, 32B-2 supply pipe 33 pumps 33A Ammonia Pump 34. Merging valve 35, 35A Dosing Unit 36 Nitrogen Oxide Sensor 37, 37A Control Unit 40 EGR device 41 Scrubber 41a Scrubber water injection part 42 Demista 42a Outflow pipe 43 EGR blower 44 Collecting Tanks 45a Alkaline solution supply unit 45b Fresh water supply section 46 pH meter 47 Control Unit 48 Water supply pipe 49 Pumps 50 Water treatment equipment 60 Ventilation System 61 Ventilation fan 62 Ventilation pipe 63 Ammonia Sensor 64 Fountain section 64a Fountain nozzle 65 Control Unit 70 Ammonia injection valve 101, 102 Exhaust pipes 101a First branch pipe 101b Second branch pipe 103 Inlet circulation pipe 104 Outlet circulation pipe 200, 200A Ammonia-containing drain 201 First mixed drain 202 Second Mixing Drain 203 Third Mixing Drain 204 Ammonia-containing liquid 205 Ammonia-containing gas 206 Mixed gas 207 Ammonia water 208 Scrubber Water 210 Internal gas

Claims

1. A fuel injection system for injecting ammonia fuel and fossil fuels into the combustion chamber of a marine diesel engine, and a recovery unit for recovering ammonia-containing drain discharged from the fuel injection system, A supply unit that supplies the ammonia component contained in the recovered ammonia-containing drain to one or more functional units that function using the ammonia component, Equipped with, The recovery unit includes at least one recovery pipe through which a mixed drain, which is a mixture of gaseous components or oily components other than the ammonia component and the ammonia fuel, is circulated. The at least one recovery pipe includes a second recovery pipe for recovering a second mixed drain, which is a mixture of the lubricating oil of the ammonia pump and the ammonia fuel, from the ammonia pump that pumps the ammonia fuel to the fuel injector of the fuel injection system. A drain treatment apparatus characterized by the following:

2. The aforementioned recovery unit is A recovery tank collects the mixed drain from the fuel injection system through the at least one recovery pipe and stores the ammonia-containing drain containing at least one of the gaseous component and the oil component and the ammonia fuel. The drain treatment apparatus according to claim 1, characterized by comprising:

3. The recovery tank is a gas-liquid separator that separates the stored ammonia-containing drain into an ammonia-containing liquid containing the oil component and the ammonia fuel, and an ammonia-containing gas containing the gaseous component and ammonia gas vaporized from the ammonia fuel. The aforementioned supply unit is An extraction unit for removing the oil component from the ammonia-containing liquid and extracting the ammonia component, An ammonia water generating unit that adds water to the ammonia-containing gas to separate the gaseous component from the ammonia gas and to produce an aqueous solution of the ammonia gas containing the ammonia component, The drain treatment apparatus according to claim 2, characterized by comprising:

4. One of the one or more functional units is an exhaust gas treatment apparatus comprising: a reactor that removes nitrogen oxides contained in exhaust gas by a reduction reaction between the nitrogen oxides and a reducing agent; a mixer that mixes the exhaust gas and the reducing agent; and a reducing agent supply unit that supplies the reducing agent to the mixer. The supply unit supplies the ammonia component extracted by the extraction unit to the mixer. The drain treatment apparatus according to claim 3.

5. The supply unit adds the ammonia water generated by the ammonia water generation unit to the reducing agent. The drain treatment apparatus according to feature 4.

6. One of the one or more functional units is a drive system for the marine diesel engine that generates driving force by utilizing the energy from the co-combustion of the ammonia fuel and the fossil fuel injected into the combustion chamber. The supply unit injects the ammonia water generated by the ammonia water generation unit into the combustion chamber. The drain treatment apparatus according to feature 3 or 4.

7. The at least one recovery pipe includes a first recovery pipe that recovers a first mixed drain, which is a mixture of the fossil fuel and the ammonia fuel, from the fuel injection valve of the fuel injection system. A drain treatment apparatus according to any one of features 1 to 6.

8. The at least one recovery pipe includes a third recovery pipe that recovers a third mixed drain, which is a mixture of purge gas purging the inside of a connecting pipe and the ammonia fuel, from a connecting pipe that connects the fuel injection valve of the fuel injection system to an ammonia pump that pumps the ammonia fuel to the fuel injection valve. A drain processing apparatus according to any one of features 1 to 7.

9. One of the one or more functional units is a collecting tank that stores and neutralizes the acidic scrubber water used for cleaning a portion of the exhaust gas discharged from the marine diesel engine with scrubber water and returning it to the marine diesel engine in an EGR system. The supply unit supplies the ammonia water generated by the ammonia water generation unit to the collecting tank. The drain treatment apparatus according to feature 3 or 4.

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