Exhaust treatment system, internal combustion engine system, control method and control program for exhaust treatment system

Abstract

The present invention provides an exhaust treatment system, an internal combustion engine system, a control method for the exhaust treatment system, and a control program that are less prone to malfunctions. [Solution] The exhaust treatment system 3 comprises a catalyst 31, a regeneration processing unit 32, and a control unit. The catalyst 31 purifies unburned fuel gas components contained in the exhaust gas discharged from the engine body, which is driven by a supply of fuel gas. The regeneration processing unit 32 supplies regeneration fuel to a position upstream of the catalyst 31 in the direction of exhaust flow in the exhaust path 25 through which the exhaust gas passes, and burns the regeneration fuel in the catalyst 31 to raise the temperature of the catalyst 31, thereby performing a regeneration treatment of the catalyst 31. The control unit controls the operation of the regeneration processing unit 32 based on the state of the exhaust gas.

Description

Technical Field

[0001] The present invention relates to an exhaust gas treatment system that decomposes unburned components of fuel gas contained in exhaust gas discharged from an engine main body, an internal combustion engine system, a control method for the exhaust gas treatment system, and a control program.

Background Art

[0002] As related art, an exhaust gas treatment (purification) system is known that includes an exhaust passage through which exhaust gas from an engine main body (internal combustion engine) passes, and a catalyst that is provided in the exhaust passage and purifies nitrogen oxides (NO X ) in the exhaust gas (for example, see Patent Document 1). In rich spike control that temporarily sets the air-fuel ratio of exhaust gas to the rich side, the exhaust gas treatment system according to the related art adds a reducing agent to the exhaust gas passing through the exhaust passage by one or more reducing agent discharge operations, thereby performing a regeneration process (SO X poisoning recovery process) that regenerates the purification capacity.

[0003] When supplying the reducing agent to the catalyst to reduce NO X and SO X on the catalyst, this exhaust gas treatment system changes the flow velocity (flow rate) of the exhaust gas passing through the exhaust passage, and adds the reducing agent at a plurality of timings with different flow velocities during the change of the flow velocity.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of Invention

Problems to be Solved by the Invention

[0005] However, with the above-mentioned related technologies, for example, when applied to large internal combustion engine systems, the volume of the exhaust path becomes large, and it takes time for the fuel-rich atmosphere gas to reach the catalyst. This raises concerns about malfunctions such as flue explosions due to autoignition of fuel within the exhaust path.

[0006] The object of the present invention is to provide an exhaust treatment system, an internal combustion engine system, a control method for the exhaust treatment system, and a control program that are less prone to malfunctions. [Means for solving the problem]

[0007] An exhaust treatment system according to one aspect of the present invention comprises a catalyst, a regeneration processing unit, and a control unit. The catalyst purifies unburned components of the fuel gas contained in the exhaust gas discharged from an engine body that is driven by a supply of fuel gas. The regeneration processing unit supplies regeneration fuel to a position upstream of the catalyst in the direction of the exhaust flow in the exhaust path through which the exhaust gas passes, and burns the regeneration fuel in the catalyst to raise the temperature of the catalyst, thereby performing a regeneration treatment of the catalyst. The control unit controls the operation of the regeneration processing unit based on the state of the exhaust gas.

[0008] An internal combustion engine system according to one aspect of the present invention comprises the exhaust treatment system and the engine body.

[0009] A control method for an exhaust gas treatment system according to one aspect of the present invention is a control method for an exhaust gas treatment system comprising a catalyst, a regeneration processing unit, and a control unit. The catalyst purifies unburned components of the fuel gas contained in the exhaust gas discharged from an engine body that is driven by a supply of fuel gas. The regeneration processing unit supplies regeneration fuel to a position upstream of the catalyst in the direction of the exhaust gas flow in the exhaust gas path, burns the regeneration fuel in the catalyst to raise the catalyst's temperature, and performs regeneration processing on the catalyst. The control method comprises controlling the operation of the regeneration processing unit based on the state of the exhaust gas.

[0010] A control program according to one aspect of the present invention is a program that causes one or more processors to execute the control method for the exhaust gas treatment system. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide an exhaust treatment system, an internal combustion engine system, a control method for the exhaust treatment system, and a control program that are less prone to malfunctions. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 is a schematic diagram showing the configuration of an internal combustion engine system according to Embodiment 1. [Figure 2] Figure 2 is a schematic diagram showing the configuration of the main parts of the exhaust treatment system according to Embodiment 1. [Figure 3] Figure 3 is a schematic diagram showing the configuration of the main parts of the exhaust treatment system according to Embodiment 1. [Figure 4] Figure 4 shows a simulation result illustrating an example of the residence time until autoignition of the regenerative fuel in relation to the exhaust treatment system according to Embodiment 1. [Figure 5] Figure 5 is a flowchart showing an example of the operation of the exhaust treatment system according to Embodiment 1. [Figure 6] Figure 6 is a schematic diagram showing the effect of the partition in the exhaust treatment system according to Embodiment 1. [Modes for carrying out the invention]

[0013] The embodiments of this disclosure will be described below with reference to the attached drawings. The following embodiments are examples that embody this disclosure and are not intended to limit the technical scope of this disclosure. The drawings referenced in this disclosure are all schematic diagrams, and the ratios of the size and thickness of each component in the drawings do not necessarily reflect the actual dimensional ratios.

[0014] (Embodiment 1) [1] Overall configuration of the internal combustion engine system First, the overall configuration of the internal combustion engine system 100 according to the present embodiment will be described with reference to Figure 1. In Figure 1, the flow of air (intake air and exhaust gas) is schematically indicated by outlined arrows.

[0015] As shown in Figure 1, the internal combustion engine system 100 according to the present embodiment includes an engine main body 2 that serves as the main component of the internal combustion engine system 100. The engine main body 2 includes the engine main body 2 that serves as the main component of the internal combustion engine system 100. The term "engine" as used herein refers to a heat engine that combusts fuel to generate mechanical energy (power), and includes an internal combustion engine which is a prime mover in which fuel combustion is performed inside the engine and thermal energy is converted into mechanical energy using combustion gas as working gas. That is, the engine main body 2 generates power (mechanical energy) using the supplied fuel.

[0016] In the present embodiment, as an example, the internal combustion engine system 100 used for a vessel will be described. That is, the internal combustion engine system 100 is mounted on the hull of the vessel. The engine main body 2 of the internal combustion engine system 100 is used as a drive source for generating propulsive force that propels the hull.

[0017] Further in the present embodiment, the engine main body 2 of the internal combustion engine system 100 can also be used as a drive source for driving a generator that generates electric energy (electric power) to be used on the hull. That is, the engine main body 2 of the internal combustion engine system 100 is used as a drive source for generating propulsive force of the hull or for driving the generator of the hull. The electric energy generated by the generator may be stored in an electrical storage device.

[0018] A ship is a mobile body that navigates (travels) on water such as the sea, lakes, or rivers. In the present embodiment, as an example, the ship is a large-scale ship that navigates a relatively long distance with one refueling, such as an ocean-going vessel. The hull of the ship is provided with a propeller. The propeller is connected to the engine main body 2 of the internal combustion engine system 100 via a propeller shaft. The ship generates propulsive force for moving the hull forward or backward by rotating the propeller around the propeller shaft under the power generated by the engine main body 2.

[0019] The engine main body 2 according to the present embodiment is a reciprocating engine that converts reciprocating motion of a piston into rotational motion and outputs rotational force as power. That is, the internal combustion engine system 100 generates propulsive force for the hull by rotating the propeller of the hull with the rotational force generated by the engine main body 2.

[0020] Further, in the present embodiment, the ship is configured to operate in response to an operation (including remote operation) by a person (operator), and is particularly a manned type that allows the operator as a person to board. Therefore, the ship has an operation panel on the hull that receives operations from the operator, and drives the engine main body 2 of the internal combustion engine system 100 in response to operations on the operation panel. This allows the ship to drive the engine main body 2 in accordance with the operator's operation and rotate the propeller to move the hull forward or backward. Further, the hull is further provided with various onboard facilities including a steering mechanism, a display device, a communication device, lighting equipment, and the like.

[0021] Incidentally, the engine main body 2 according to the present embodiment is a gas engine that is driven by being supplied with fuel gas. Specifically, the engine main body 2 is a (methane) gas engine that uses natural gas containing methane (CH4) as a main component as fuel gas. That is, in the internal combustion engine system 100, the engine main body 2 is driven by supplying fuel gas composed of natural gas (methane gas) containing methane (CH4) as a main component to the engine main body 2 by the gas fuel supply device 101.

[0022] The engine body 2 has multiple cylinders 21, each cylinder 21 housing a piston that can reciprocate. The piston is connected to the crankshaft via a connecting rod. An intake manifold 22 and an exhaust manifold 23 are connected to the combustion chamber of each cylinder 21.

[0023] The intake manifold 22 is connected to multiple cylinders 21 (combustion chambers) via multiple intake ports, and air is distributed from the intake manifold 22 to the multiple intake ports. In other words, the intake manifold 22 leads to the combustion chamber of each cylinder 21 through the intake ports.

[0024] The exhaust manifold 23 is connected to multiple cylinders 21 (combustion chambers) via multiple exhaust ports, and the exhaust from the multiple exhaust ports is collected in the exhaust manifold 23. In other words, the exhaust manifold 23 leads to the combustion chamber of each cylinder 21 through the exhaust ports.

[0025] The internal combustion engine system 100 includes an intake path 24 and an exhaust path 25. The intake path 24 is a path (piping) for taking air into the intake manifold 22. The exhaust path 25 is a path (piping) for discharging exhaust from the exhaust manifold 23.

[0026] Here, the internal combustion engine system 100 is configured to be able to supply fuel gas (in this case, methane gas) to the engine body 2, which is a gas engine, from outside the engine body 2. That is, as shown in Figure 1, the internal combustion engine system 100 is equipped with a gas fuel supply device 101 for supplying fuel gas.

[0027] The gas fuel supply device 101 generates fuel gas from a tank that stores liquefied natural gas (LGN), which is natural gas mainly composed of methane, and supplies it to the engine body 2. Specifically, the gas fuel supply device 101 vaporizes the liquefied natural gas to generate natural gas (methane gas) as fuel gas, and injects this fuel gas into the intake passage 24. As a result, the fuel gas is supplied to the cylinders 21 (combustion chambers) of the engine body 2 via the intake manifold 22 as a mixture with the air (intake) flowing through the intake passage 24.

[0028] Furthermore, the internal combustion engine system 100 according to this embodiment is a supercharged engine that includes a supercharger 26 in addition to the engine body 2. However, the supercharger 26 is not an essential component of the internal combustion engine system 100 and can be omitted as appropriate.

[0029] The turbocharger 26 (and its turbine) is located on the exhaust path 25. When the turbine of the turbocharger 26 rotates due to the flow of air (exhaust) discharged through the exhaust path 25, it rotates the compressor on the intake path 24, compressing the air (intake air) taken in from the intake path 24 and sending it to the intake manifold 22.

[0030] According to the internal combustion engine system 100 with the above configuration, when the engine body 2 is driven, the mixture of fuel gas and air supplied from the intake manifold 22 to each cylinder 21 is burned, causing the piston to reciprocate within the cylinder 21. The reciprocating motion of the piston is converted into rotational motion of the crankshaft via the connecting rod. As a result, the engine body 2 outputs the rotational force of the crankshaft as power (mechanical energy).

[0031] When the engine body 2 is in operation, the exhaust gas generated by combustion in the combustion chamber is pushed out of the cylinder 21 by the reciprocating motion of the piston, collected in the exhaust manifold 23, and then discharged to the outside of the engine body 2 through the exhaust path 25.

[0032] With this type of internal combustion engine system 100, liquefied natural gas stored in a tank is vaporized each time by a gas fuel supply device 101 to obtain natural gas (methane gas) as fuel gas. This improves the volumetric energy density of the stored material compared to storing the fuel gas in a gaseous state. Therefore, if the tank capacity is the same, more fuel gas can be stored, and if the same amount of fuel gas is to be stored, a smaller tank is sufficient. This ability to efficiently supply fuel gas (with a smaller tank) is particularly useful for ships that travel relatively long distances on a single refueling, such as ocean-going vessels.

[0033] Incidentally, as shown in Figure 1, the internal combustion engine system 100 according to this embodiment further includes an exhaust treatment system 3 in addition to the engine body 2, etc.

[0034] The exhaust treatment system 3 is a system for purifying the exhaust gas discharged from the engine body 2. By purifying the exhaust gas discharged from the engine body 2, the exhaust treatment system 3 ensures that the internal combustion engine system 100 meets the desired emission regulations. The exhaust treatment system 3 is inserted into the exhaust path 25 connected to the exhaust manifold 23 of the engine body 2. As a result, the air (exhaust) discharged to the outside of the internal combustion engine system 100 through the exhaust path 25 passes through the exhaust treatment system 3 and is purified by the exhaust treatment system 3.

[0035] The exhaust treatment system 3 according to this embodiment includes a catalyst 31 (see Figure 1) inserted into the exhaust path 25. The exhaust treatment system 3 purifies the exhaust by decomposing methane (a non-combustible component of fuel gas) contained in the exhaust passing through the exhaust path 25 using the catalyst 31.

[0036] [2] Definition In this disclosure, "decomposition" refers to a type of chemical reaction in which a compound is broken down into its individual components or simpler compounds, which is the reverse process of chemical synthesis. Decomposition usually requires an external energy supply, and depending on the energy source, there are various types of decomposition, such as thermal decomposition, photodecomposition, electrolysis, or radiolysis. In this embodiment, as an example, the exhaust gas treatment system 3 uses a catalyst 31 to oxidize methane (CH4), a non-combustible component of the fuel gas, and decompose it into carbon dioxide (CO2) and water (H2O). However, the exhaust gas treatment system 3 only needs to decompose at least a portion of the non-combustible component (methane) of the fuel gas contained in the exhaust gas; it is not essential to decompose the entire amount.

[0037] In this disclosure, a "catalyst" is a substance that promotes a chemical reaction, such as decomposition, without changing itself. More precisely, a "catalyst" interacts with the reaction in some way, and sometimes the "catalyst" itself changes, thereby altering the reaction pathway and promoting the reaction. After the reaction, the "catalyst" returns to its original state, and as a result, the "catalyst" itself remains unchanged. In this embodiment, as an example, the exhaust gas treatment system 3 is equipped with a catalyst 31 (methane oxidation catalyst) that oxidizes and decomposes methane, a non-combustible component of fuel gas, and the catalyst 31 is used to decompose methane.

[0038] [3] Details of the exhaust treatment system Next, the details of the exhaust treatment system 3 according to this embodiment will be described with reference to Figures 1 and 2.

[0039] In this embodiment, the exhaust treatment system 3, as shown in Figure 1, includes a catalyst 31, a regeneration processing unit 32, a control unit 33, and a sensor 34.

[0040] The catalyst 31 purifies unburned components of fuel gas contained in the exhaust. The catalyst 31 is inserted into the exhaust path 25 connected to the exhaust manifold 23. As a result, the air (exhaust) discharged to the outside of the internal combustion engine system 100 through the exhaust path 25 passes through the catalyst 31, and as the exhaust passes through the catalyst, methane, which is an unburned component of fuel gas in the exhaust, is purified. Therefore, the amount of unburned components (methane) of fuel gas in the exhaust discharged to the outside of the internal combustion engine system 100 is reduced.

[0041] To explain in more detail, in engine body 2, which uses natural gas (methane gas) as fuel, there is a concern about "methane slip," which is the emission of unburned methane, a type of greenhouse gas that has a greenhouse effect about 25 times higher than carbon dioxide. Methane slip is thought to be caused, for example, by a tiny gap that occurs near the piston ring in cylinder 21, or by the flame not reaching the surface of the cylinder wall, resulting in methane (unburned methane) mixing into the exhaust.

[0042] Therefore, in this embodiment, the exhaust gas treatment system 3 uses a catalyst 31 inserted into the exhaust gas path 25 to purify the unburned fuel gas components (methane) contained in the exhaust gas. Specifically, the catalyst 31 is a methane oxidation catalyst that oxidizes methane (CH4) in the exhaust gas to decompose (convert) it into carbon dioxide (CO2) and water (H2O). Such a catalyst 31 can be realized using, for example, platinum (Pt) or palladium (Pd), which are platinum-based precious metals. In this embodiment, as an example, the catalyst 31 is made of a platinum (Pt) catalyst.

[0043] However, in this type of catalyst 31, sulfur compounds (SO X The catalyst 31 may be poisoned by the catalyst 31, which can reduce the methane purification rate (decomposition rate) by the catalyst 31. For example, although natural gas as a fuel gas mainly consists of methane, it generally contains various sulfur compounds as impurities, and these sulfur compounds contained in the exhaust gas can poison the catalyst 31.

[0044] Therefore, in the exhaust gas treatment system 3 according to this embodiment, the regeneration unit 32 periodically or irregularly raises the temperature of the catalyst 31 whose performance has deteriorated due to sulfur poisoning, thereby regenerating (restoring) the purification capacity of the catalyst 31 (SO X A poisoning recovery treatment is performed. In other words, the regeneration unit 32 can regenerate the methane purification and decomposition (capacity) of the catalyst 31 by raising the temperature of the catalyst 31 in some way.

[0045] Generally, there are three methods for regenerating the catalyst 31: the post-injection method, the exhaust pipe fuel injection method, and the heater heating method.

[0046] The post-injection method adds post-injection to combustion in the engine body 2, burning unburned fuel on the catalyst 31 and raising the temperature of the catalyst 31 through oxidation heat. The exhaust pipe fuel injection method injects regenerative fuel upstream of the catalyst 31 in the exhaust flow direction in the exhaust path 25, burns the regenerative fuel on the catalyst 31, and raises the temperature of the catalyst 31 through oxidation heat. The heater heating method places a heating element such as a heater inside or around the catalyst 31 and directly raises the temperature of the catalyst 31 with the heating element.

[0047] The exhaust treatment system 3 according to this embodiment employs an exhaust pipe fuel injection method for regeneration among these regeneration processes. Specifically, the regeneration processing unit 32 supplies regeneration fuel to a position upstream of the catalyst 31 in the direction of exhaust flow in the exhaust path 25 through which the exhaust gas passes, and burns the regeneration fuel in the catalyst 31 to raise the temperature of the catalyst 31, thereby performing regeneration of the catalyst 31. The exhaust pipe fuel injection method does not affect the combustion of the engine body 2, has a high degree of freedom in the range of possible temperature increases, and (because the temperature is raised directly by the combustion of the regeneration fuel) the temperature rise rate of the catalyst 31 is also fast. The position in the exhaust path 25 where the regeneration fuel is supplied is also called the "supply position".

[0048] In this disclosure, "regeneration fuel" refers to fuel supplied by the regeneration processing unit 32 to a position upstream of the catalyst 31 in the exhaust flow direction in the exhaust path 25 (supply position), and is used for the combustion of the catalyst 31 for regeneration processing. In this embodiment, as an example, the regeneration fuel is diesel fuel or a hydrocarbon fuel such as methane, and specifically diesel fuel.

[0049] In other words, the regeneration unit 32 has a fuel supply unit that supplies hydrocarbon fuel (diesel oil) as regeneration fuel to the supply position in the exhaust path 25. The regeneration fuel (diesel oil) supplied from the fuel supply unit of the regeneration unit 32 into the exhaust path 25 is supplied to the catalyst 31 located downstream of the supply position, together with the exhaust gas flowing through the exhaust path 25. As the regeneration fuel (diesel oil) supplied to the catalyst 31 in this way burns in the catalyst 31, the catalyst 31 is heated up and the catalyst 31 is regenerated.

[0050] Furthermore, in this embodiment, the regeneration unit 32 supplies gas in addition to the regeneration fuel to a position upstream of the catalyst 31 in the exhaust flow direction of the exhaust path 25 during the regeneration process. The regeneration unit 32 supplies the regeneration fuel and gas by two-fluid spray from one or more injection nozzles. In other words, during the execution of the regeneration process, the regeneration unit 32 does not supply the regeneration fuel (diesel oil) alone to a position (supply position) upstream of the catalyst 31 in the exhaust flow direction of the exhaust path 25, but supplies the regeneration fuel (diesel oil) and gas together by two-fluid spray. Here, the gas supplied together with the regeneration fuel is, for example, compressed air, but is not limited to this, and may be, for example, oxygen or an inert gas.

[0051] Specifically, as shown in Figure 2, the regeneration unit 32 has a two-fluid nozzle 321. The two-fluid nozzle 321 is a nozzle that uses a high-speed flow of gas (compressed air in this case) to mix a liquid (regeneration fuel in this case) with the gas and atomize it. The two-fluid nozzle 321 makes it possible to atomize particles with a diameter of 10 μm or less, which is difficult with a single-fluid nozzle, and allows for a large adjustment range (turndown ratio) of the spray flow rate while maintaining a constant particle size and flow rate distribution, making it suitable as a spray flow rate adjustment nozzle. Furthermore, the two-fluid nozzle 321 has a larger foreign matter passage diameter compared to a single-fluid nozzle of the same flow rate, making it effective in preventing clogging.

[0052] Therefore, the regeneration processing unit 32 can inject even a small amount of regeneration fuel by supplying the regeneration fuel and gas by two-fluid atomization, and the particle size (diameter) and injection angle of the regeneration fuel can be easily adjusted. In this disclosure, "particle size" refers to the diameter of a particle (in this case, a particle of regeneration fuel), and in the case of multiple (many) particles, it refers to a representative value such as the average value, median, mode, minimum value, and / or maximum value for those multiple particles.

[0053] Furthermore, in the two-fluid spray system, the particle size of the regenerating fuel, the injection angle, and the angle between the central axes of each injection port are all kept within appropriate ranges so that the evaporation of the regenerating fuel is completed within a predetermined range of the exhaust path 25. This prevents the liquid regenerating fuel supplied into the exhaust path 25 from coming into contact with the catalyst 31 while remaining in liquid (droplet) form, thereby preventing damage (burnout) of the catalyst 31 due to a rapid temperature rise on the catalyst 31.

[0054] In other words, in a two-fluid spray, the particle size of the regenerative fuel is kept within the range of 40 μm to 220 μm, more preferably 60 μm to 120 μm, so that the evaporation of the regenerative fuel is completed within a predetermined range of the exhaust path 25. Furthermore, in a two-fluid spray, the spray angle of the regenerative fuel is kept within the range of 15 degrees to 60 degrees so that the evaporation of the regenerative fuel is completed within a predetermined range of the exhaust path 25. Moreover, in a two-fluid spray, the angle between the central axes of each injection port of the regenerative fuel is kept within the range of 20 degrees to 90 degrees so that the evaporation of the regenerative fuel is completed within a predetermined range of the exhaust path 25.

[0055] In other words, if the liquid regenerating fuel supplied into the exhaust path 25 comes into contact with the catalyst 31 while still in liquid (droplet) form, a very small but rapid temperature rise will occur on the catalyst 31, which could lead to damage (burnout) of the catalyst 31. Therefore, it is preferable that the fuel evaporates within a predetermined range before reaching the catalyst 31. For example, the larger the particle size of the regenerating fuel injected in a two-fluid spray, the longer the time required for the regenerating fuel to evaporate. To ensure evaporation before reaching the catalyst 31, it is necessary to ensure a long exhaust path 25 from the supply point to the catalyst 31. However, it is difficult to ensure a long exhaust path 25 in the installation space of the internal combustion engine system 100.

[0056] Furthermore, when droplets (liquid) are injected into a high-temperature exhaust atmosphere, the Leidenfrost effect can cause the droplets to bounce off the walls of the exhaust path 25 (pipe walls), and these bounced droplets may combine with other droplets and grow. As a result, if the spray condition of the regenerative fuel into the exhaust path 25 becomes irregular, the combustion reaction may be accelerated, which can lead to damage (burnout) of the catalyst 31.

[0057] In this embodiment, the particle size and injection angle of the regenerative fuel are both kept within appropriate ranges so that the evaporation of the regenerative fuel is completed within a predetermined range of the exhaust path 25. Therefore, even without ensuring a long exhaust path 25, burnout of the catalyst 31 due to a rapid temperature rise can be suppressed. In addition, the injection angle of the regenerative fuel (from the two-fluid nozzle 321) suppresses the bounce of droplets (regenerative fuel) off the walls (pipe walls) of the exhaust path 25, thereby suppressing the acceleration of the combustion reaction and preventing burnout of the catalyst 31.

[0058] The control unit 33 primarily consists of a computer system comprising one or more processors such as a CPU (Central Processing Unit) and one or more memories such as ROM (Read Only Memory) and RAM (Random Access Memory), and performs various processes (information processing). One or more memories in the control unit 33 store programs (control programs) that cause one or more processors to execute the control method for the exhaust treatment system 3.

[0059] The control unit 33 controls the operation of at least the regeneration processing unit 32 of the exhaust treatment system 3. The control unit 33 switches the supply / stop of regeneration fuel to at least the exhaust path 25. When regeneration fuel is supplied, the regeneration process of the catalyst 31 is performed (permitted), and when the supply of regeneration fuel is stopped, the regeneration process of the catalyst 31 is stopped (prohibited).

[0060] In other words, the control unit 33 controls the regeneration processing unit 32 to supply regeneration fuel to a position upstream of the catalyst 31 in the exhaust flow direction of the exhaust path 25 (supply position), thereby causing the catalyst 31 to regenerate. On the other hand, the control unit 33 stops the regeneration processing of the catalyst 31 by controlling the regeneration processing unit 32 to stop the supply of regeneration fuel.

[0061] In this embodiment, the control unit 33 also serves as a control unit that comprehensively controls not only the exhaust treatment system 3 but the entire internal combustion engine system 100. In other words, the control unit 33 controls not only the exhaust treatment system 3 (specifically the regeneration processing unit 32) but also the engine body 2 and the gas fuel supply device 101, etc. The control unit 33 outputs control signals (electrical signals) to the regeneration processing unit 32, the engine body 2, and the gas fuel supply device 101, etc., thereby controlling the regeneration processing unit 32, the engine body 2, and the gas fuel supply device 101, etc. This makes it possible for the control unit 33 to control the engine body 2 so that its output (mainly rotational speed) can be adjusted to an arbitrary value.

[0062] Sensor 34 is a physical quantity sensor located in the exhaust path 25 through which exhaust gas passes. Examples of this type of physical quantity sensor include temperature sensors, oxygen concentration sensors, flow meters, and pressure sensors. The temperature sensor measures the temperature of the exhaust gas passing through the exhaust path 25. The oxygen concentration sensor measures the oxygen concentration of the exhaust gas passing through the exhaust path 25. The flow meter measures the flow velocity (or flow rate) of the exhaust gas passing through the exhaust path 25. The pressure sensor measures the pressure of the exhaust gas in the exhaust path 25. Sensor 34 outputs an electrical signal to the control unit 33 according to the measured value (temperature, oxygen concentration, flow velocity, or pressure, etc.).

[0063] The exhaust treatment system 3 according to this embodiment includes a sensor 34 consisting of at least a temperature sensor. The temperature sensor is placed in the exhaust path 25 through which the exhaust gas passes and measures the temperature of the exhaust gas. By providing such a temperature sensor (sensor 34) in the exhaust path 25, it is possible to directly and accurately measure the temperature of the exhaust gas in the exhaust path 25 through which the regenerative fuel is supplied.

[0064] Furthermore, the internal combustion engine system 100 may also be equipped with an exhaust gas recirculation device. The exhaust gas recirculation device is a device that recirculates at least a portion of the exhaust gas discharged from the engine body 2 as EGR (Exhaust Gas Recirculation) gas from the exhaust port to the intake port of the engine body 2. However, the exhaust gas recirculation device is not an essential component of the internal combustion engine system 100 and can be omitted as appropriate.

[0065] As described above, the exhaust treatment system 3 according to this embodiment includes a catalyst 31, a regeneration processing unit 32, and a control unit 33. The catalyst 31 purifies unburned fuel gas components contained in the exhaust gas discharged from the engine body 2, which is driven by a supply of fuel gas. The regeneration processing unit 32 supplies regeneration fuel (hydrocarbon fuel) to a position upstream of the catalyst 31 in the direction of exhaust flow in the exhaust path 25 through which the exhaust gas passes, and burns the regeneration fuel in the catalyst 31 to raise the temperature of the catalyst 31, thereby performing a regeneration treatment of the catalyst 31. The control unit 33 controls the operation of the regeneration processing unit 32. Here, the control unit 33 controls the operation of the regeneration processing unit 32 based on the state of the exhaust gas (passing through the exhaust path 25).

[0066] According to the above configuration, the operation of the regeneration processing unit 32 is controlled (at least switching between supplying regeneration fuel (executing regeneration processing) and stopping the supply of regeneration fuel (stopping regeneration processing)) based on the state of the exhaust passing through the exhaust path 25. As will be explained in detail in the section "[4] Operation of the Exhaust Treatment System", by controlling the operation based on the state of the exhaust, it becomes possible to control the operation of the regeneration processing unit 32 in a way that avoids problems such as flue explosions due to autoignition of regeneration fuel within the exhaust path 25. Therefore, regardless of the length, diameter, and shape of the exhaust path 25 (such as the presence or absence of bends), an exhaust treatment system 3 and an internal combustion engine system 100 can be realized in which problems such as flue explosions due to autoignition of regeneration fuel within the exhaust path 25 are less likely to occur.

[0067] In particular, in this embodiment, the fuel gas supplied to the engine body 2 is natural gas (methane gas) with methane as its main component. There is a concern about "methane slip," which is the emission of unburned methane, a type of greenhouse gas whose greenhouse effect is about 25 times higher than that of carbon dioxide. The exhaust treatment system 3 according to this embodiment is very useful in this regard. In other words, this exhaust treatment system 3 suppresses the occurrence of malfunctions such as flue explosions, and the purification and decomposition (capacity) of methane by the catalyst 31 is regenerated through regeneration treatment, making it less likely for "methane slip" to occur.

[0068] [4] Operation of the exhaust treatment system Next, the operation of the exhaust treatment system 3 according to this embodiment, and the control method of the exhaust treatment system 3 which is mainly realized by the operation of the control unit 33, will be explained with reference to Figures 3 to 5.

[0069] As described above, the control unit 33 controls the operation of the regeneration processing unit 32 based on the state of the exhaust (passing through the exhaust path 25). In other words, the control unit 33 switches between supplying regeneration fuel (executing regeneration processing) and stopping the supply of regeneration fuel (stopping regeneration processing) based on the state of the exhaust.

[0070] Here, the exhaust state includes at least one of the exhaust temperature, oxygen concentration, and flow velocity. In other words, the “exhaust state” as used in this disclosure refers to the exhaust temperature, the oxygen concentration of the exhaust, and / or the flow velocity of the exhaust. The control unit 33 controls the operation of the regeneration processing unit 32 based on such exhaust state, which has the advantage of making it less likely for problems such as flue explosions in the exhaust path 25 due to autoignition of the regeneration fuel to occur.

[0071] The significance of controlling the operation of the regeneration processing unit 32 based on the exhaust gas condition will be explained in more detail below.

[0072] As schematically shown in Figure 3, when the regeneration unit 32 supplies regeneration fuel at a position upstream of the catalyst 31 in the exhaust flow direction in the exhaust path 25 (supply position), the regeneration fuel moves downstream (towards the catalyst 31) along with the exhaust flow in the exhaust path 25. In other words, the regeneration fuel moves within the exhaust path 25 over the flue distance L1 from the supply position supplied by the regeneration unit 32 to the catalyst 31. Therefore, the regeneration fuel remains within the exhaust path 25 from the time it is supplied to the exhaust path 25 until it reaches the catalyst 31.

[0073] Here, if the residence time ("residence time") of hydrocarbon fuel (for example, diesel fuel) used as a regenerative fuel (at a relatively high concentration) is short within the exhaust path 25, the risk of malfunctions such as flue explosions due to autoignition of the regenerative fuel within the exhaust path 25 is reduced. On the other hand, if the residence time of hydrocarbon fuel used as a regenerative fuel is long, the risk of malfunctions such as flue explosions increases. For example, in relatively large systems such as the internal combustion engine system 100 used in ships, the flue distance L1 in the exhaust path 25 tends to be long due to layout constraints, and the risk of malfunctions such as flue explosions tends to be higher.

[0074] Therefore, in the exhaust treatment system 3 according to this embodiment, it is determined whether autoignition of the regenerative fuel occurs while it is remaining in the exhaust path 25, based on the "exhaust state," which includes at least one of the exhaust temperature, oxygen concentration, and flow velocity. If it is determined that autoignition of the regenerative fuel will occur, the exhaust treatment system 3 stops the supply of the regenerative fuel and stops the regeneration process, thereby suppressing the occurrence of malfunctions such as flue explosions due to autoignition of the regenerative fuel.

[0075] Specifically, the control unit 33 permits the regeneration process if the first time T1, which is required from the time the regeneration fuel is supplied until it autoignites, is equal to or greater than the second time T2, which is required from the time the regeneration fuel is supplied until it reaches the catalyst 31. Here, the first time T1 is the time from the time the regeneration fuel is supplied to the exhaust path 25 by the regeneration processing unit 32 until it autoignites in the exhaust atmosphere. The second time T2 is the time from the time the regeneration fuel is supplied to the exhaust path 25 by the regeneration processing unit 32 until the regeneration fuel travels the flue distance L1 along the exhaust flow and reaches the catalyst 31.

[0076] That is, when the first time T1 is equal to or longer than the second time T2 (T1≧T2), if regeneration of the catalyst 31 is necessary, the control unit 33 causes the regeneration processing unit 32 to supply the regeneration fuel and execute the regeneration process. On the other hand, when the first time T1 is less than the second time T2 (T1<T2), even if regeneration of the catalyst 31 is necessary, the control unit 33 does not cause the regeneration processing unit 32 to supply the regeneration fuel, and prohibits (does not execute) the regeneration process.

[0077] According to this configuration, when it is estimated that the regeneration fuel reaches the catalyst 31 before the regeneration fuel self-ignites in the exhaust passage 25, the regeneration process is permitted, and the regeneration processing unit 32 can perform the regeneration process as necessary. Thereby, in the exhaust passage 25, the occurrence of problems such as a flue explosion caused by self-ignition of the regeneration fuel before the regeneration fuel reaches the catalyst 31 can be suppressed.

[0078] Here, the first time T1 required from when the regeneration fuel is supplied to the exhaust passage 25 until it self-ignites depends on the temperature and oxygen concentration of the exhaust gas passing through the exhaust passage 25, as shown in FIG. 4. FIG. 4 is a simulation result showing an example of the residence time until self-ignition (identical to the first time T1) when the inner diameter (pipe diameter) is 340 mm. In FIG. 4, the horizontal axis represents the exhaust gas temperature (°C), and the vertical axis represents the oxygen concentration (%) of the exhaust gas. In FIG. 4, the region where the first time T1 is 1 second or less is illustrated as a specific region R1.

[0079] Further, the second time T2 required from when the regeneration fuel is supplied until it reaches the catalyst 31 depends on the flow velocity of the exhaust gas passing through the exhaust passage 25. That is, since the second time T2 is the time required for the regeneration fuel to move over the flue distance L1 (see FIG. 3) along with the flow of the exhaust gas, it is the time required for the regeneration fuel to move over the flue distance L1 at the flow velocity of the exhaust gas, and is obtained by dividing the flue distance L1 by the flow velocity of the exhaust gas. Since the flow velocity is the value obtained by dividing the flow rate by the cross-sectional area of the exhaust passage 25, it is naturally possible to obtain the second time T2 even when the flow rate is used instead of the flow velocity.

[0080] Furthermore, if the second time T2, which depends on the exhaust flow velocity, is longer than the first time T1, which depends on the exhaust temperature and oxygen concentration (T2 > T1), there is a possibility that the regenerative fuel may autoignite during the residence time before it reaches the catalyst 31, causing a flue explosion. Therefore, the control unit 33 controls the operation of the regeneration processing unit 32 to allow regeneration processing when the first time T1 is greater than or equal to the second time T2 (T1 ≥ T2), based on the "exhaust state" which includes at least one of the exhaust temperature, oxygen concentration, and flow velocity.

[0081] More specifically, in this embodiment, the control unit 33 determines the first time T1 based on the volume of the exhaust path 25, as well as the exhaust temperature and oxygen concentration, and determines the second time T2 based on the exhaust velocity. In other words, the first time T1, which is required from the supply of regenerative fuel until autoignition, is calculated based on the known volume of the portion of the exhaust path 25 through which the regenerative fuel passes (product of cross-sectional area and flue distance L1), as well as the exhaust temperature and oxygen concentration. The second time T2, which is required from the supply of regenerative fuel until it reaches the catalyst 31, is calculated based on the exhaust velocity (and the known flue distance L1).

[0082] Although the first time T1 and second time T2 obtained in this way are only estimates, they can be determined relatively easily and accurately because they are based on the exhaust gas conditions (temperature, oxygen concentration, and flow rate).

[0083] Here, the "exhaust state" used by the control unit 33 to control the regeneration processing unit 32 can be determined by various means. For example, the temperature of the exhaust is measured by a sensor 34 consisting of a temperature sensor placed in the exhaust path 25 through which the exhaust passes, as described above.

[0084] Furthermore, the oxygen concentration of the exhaust gas is measured by a sensor 34 consisting of an oxygen concentration sensor located in the exhaust path 25 through which the exhaust gas passes, or the control unit 33 calculates it based on the flow rate of air and / or fuel gas supplied to the engine body 2. The exhaust gas velocity is measured by a sensor 34 consisting of a flow meter located in the exhaust path 25 through which the exhaust gas passes, or the control unit 33 calculates it based on the flow rate of air and / or fuel gas supplied to the engine body 2.

[0085] Thus, in the exhaust treatment system 3 according to this embodiment, the state of the exhaust can be determined based on the output of physical quantity sensors (sensors 34 such as temperature sensors, oxygen concentration sensors, or flow meters) arranged in the exhaust path 25 through which the exhaust passes. Therefore, by providing such physical quantity sensors (sensors 34) in the exhaust path 25, it is possible to directly and accurately measure the state of the exhaust in the exhaust path 25 through which the regenerative fuel is supplied.

[0086] Alternatively, the exhaust condition is determined based on the flow rate of at least one of the air and fuel gas supplied to the engine body 2. In other words, the oxygen concentration and flow velocity of the exhaust can be easily determined (estimated) by the control unit 33 based on the flow rate of the air and / or fuel gas supplied to the engine body 2 through the intake path 24, in addition to being directly measured by the sensor 34 in the exhaust path 25.

[0087] Furthermore, in this embodiment, the regeneration processing unit 32 supplies gas in addition to the regeneration fuel to a position upstream of the catalyst 31 in the exhaust flow direction in the exhaust path 25 during the regeneration process. The regeneration processing unit 32 stops the regeneration process by stopping the supply of regeneration fuel and continuing the supply of gas.

[0088] Specifically, the control unit 33 individually controls a valve located on the supply path for regeneration fuel to the exhaust path 25 in the regeneration processing unit 32, and a valve located on the supply path for gas (compressed air) to the exhaust path 25 in the regeneration processing unit 32. During normal operation when the catalyst 31 is not being regenerated (non-regeneration), the control unit 33 closes both valves to stop the supply of both regeneration fuel and gas. When the catalyst 31 is being regenerated (regeneration), the control unit 33 opens both valves to supply both regeneration fuel and gas.

[0089] Furthermore, during the regeneration process of catalyst 31, if the second time T2 exceeds the first time T1 (T2 > T1), and the control unit 33 controls the regeneration processing unit 32 to emergency stop the regeneration process, only the valve on the regeneration fuel side is closed. In other words, if the regeneration process is to be emergency stopped while the regeneration process is in progress and regeneration fuel and gas are being supplied to the exhaust path 25, the control unit 33 stops the supply of only the regeneration fuel, while continuing to supply the gas. This allows for the simultaneous and instantaneous shutoff of the regeneration fuel and dilution of the exhaust path 25 with gas (compressed air) during an emergency stop of the regeneration process.

[0090] Furthermore, in this embodiment, as described above, the regeneration unit 32 employs a two-fluid spray, which allows for the atomization of the regeneration fuel particles by atomizing the liquid (regeneration fuel) with a gas. This shortens the evaporation distance required for the evaporation of the regeneration fuel and reduces the flue distance L1, making it easier to save space in the internal combustion engine system 100. In addition, the regeneration unit 32 makes it easier to suppress the reaching of the catalyst 31 by regeneration fuel particles with the largest particle size (particles with particularly large particle size in terms of their frequency of occurrence within the particle size distribution). Moreover, the regeneration unit 32 makes it easier to achieve a more uniform particle size distribution than when using a single-fluid nozzle, and can suppress reaction acceleration due to disturbances in the gas concentration distribution.

[0091] Furthermore, in this embodiment, the exhaust state includes a first parameter consisting of the oxygen concentration of the exhaust and a second parameter consisting of at least one of the temperature and flow velocity of the exhaust. If the oxygen concentration is above a threshold, the control unit 33 determines the control of the regeneration processing unit 32 based on both the first and second parameters. Conversely, if the oxygen concentration is below a threshold, the control unit 33 determines the control of the regeneration processing unit based only on the first parameter of the two parameters.

[0092] In short, if the oxygen concentration of the exhaust gas is above the threshold, the control unit 33 uses both the oxygen concentration of the exhaust gas (first parameter) and the temperature and / or flow rate of the exhaust gas (second parameter) to control the regeneration processing unit 32. If the oxygen concentration of the exhaust gas is below the threshold, the control unit 33 uses only the oxygen concentration of the exhaust gas (first parameter) to control the regeneration processing unit 32, and does not use the temperature and / or flow rate of the exhaust gas (second parameter).

[0093] Here, the threshold is 5% as an example. In other words, if the oxygen concentration of the exhaust is above the threshold (5%), the control unit 33 uses both the oxygen concentration of the exhaust (first parameter) and the temperature and / or flow velocity of the exhaust (second parameter) to control the regeneration processing unit 32 based on the relationship between the first time T1 and the second time T2. On the other hand, if the oxygen concentration of the exhaust is below the threshold (5%), the control unit 33 controls the regeneration processing unit 32 to stop the regeneration process, regardless of the relationship between the first time T1 and the second time T2.

[0094] For example, in the example in Figure 4, when the oxygen concentration in the exhaust becomes somewhat low (5% or less in this case), the first time T1 required from the supply of regeneration fuel to autoignition becomes short (less than 1 second) in most of the exhaust temperature range. In such cases, it is preferable to stop the regeneration process without even looking at the exhaust temperature and / or flow velocity (second parameter). Therefore, in this embodiment, as described above, a threshold is set for the oxygen concentration of the exhaust, and the regeneration process is not performed when it is below the threshold, thereby quantitatively defining the oxygen concentration at which regeneration fuel is not supplied.

[0095] Figure 5 is a flowchart showing an example of the main processes related to the regeneration of the catalyst 31, which are part of the control method for the exhaust gas treatment system 3 executed by the control unit 33.

[0096] As shown in Figure 5, the control unit 33 first calculates the first time T1 required from the time the regeneration fuel is supplied until it autoignites, based on the exhaust gas conditions (S1). At this time, the control unit 33 calculates the first time T1 based on the volume of the exhaust gas path 25, as well as the temperature and oxygen concentration of the exhaust gas. Next, the control unit 33 calculates the second time T2 required from the time the regeneration fuel is supplied until it reaches the catalyst 31, based on the exhaust gas conditions (S2). At this time, the control unit 33 calculates the second time T2 based on the exhaust gas flow velocity (and the known flue gas distance L1).

[0097] Next, the control unit 33 compares the first time T1 with the second time T2 (S3). If the first time T1 is greater than or equal to the second time T2 (S3: Yes), the control unit 33 controls the operation of the regeneration processing unit 32 to allow the regeneration process (S4). Specifically, the control unit 33 supplies regeneration fuel and gas to the exhaust path 25 and controls the regeneration processing unit 32 to perform the regeneration process of the catalyst 31.

[0098] On the other hand, if the first time T1 is less than the second time T2 (S3: No), the control unit 33 determines whether or not regeneration is in progress (S5). If regeneration is in progress (S5: Yes), the control unit 33 controls the regeneration processing unit 32 to stop supplying only the regeneration fuel and gas, while continuing to supply the gas to the exhaust path 25. If regeneration is not in progress (S5: No), the control unit 33 controls the regeneration processing unit 32 to stop supplying both the regeneration fuel and gas.

[0099] When the control unit 33 performs the regeneration process of the catalyst 31, it repeatedly executes the processes in steps S1 to S7 described above. However, the flowchart shown in Figure 5 is merely an example, and processes may be added or omitted as appropriate, or the order of processes may be changed as appropriate.

[0100] Incidentally, as shown in Figure 6, it is preferable that the exhaust treatment system 3 further includes a partition section 27 that divides the exhaust path 25 into two or more spaces, located upstream of the catalyst 31 in the direction of exhaust flow in the exhaust path 25. In Figure 6, the exhaust flow is shown by dotted arrows. The partition section 27 can be realized, for example, by guide vanes arranged concentrically within the exhaust path 25. By providing such a partition section 27, even if the cross-sectional diameter of the catalyst 31 is larger than the pipe diameter of the exhaust path 25 just before the exhaust containing the liquid (regeneration fuel) injected for regeneration reaches the catalyst 31, exhaust stagnation is less likely to occur, and the time until it reaches the catalyst 31 can be shortened. It is preferable that the partition section 27 is located just before the catalyst 31 and in a part of the exhaust path 25 where the pipe diameter is increased.

[0101] [5] Variant The following lists some modifications of Embodiment 1. The modifications described below can be combined and applied as appropriate.

[0102] The exhaust treatment system 3 in this disclosure includes a computer system as a control unit 33. The computer system mainly consists of one or more processors and one or more memories as hardware. The functions of the control unit 33 in this disclosure are realized by the execution of a program recorded in the memory of the computer system by the processor. The program may be pre-recorded in the memory of the computer system, provided via a telecommunications line, or provided on a non-temporary recording medium such as a memory card, optical disk, or hard disk drive that can be read by the computer system. Furthermore, some or all of the functional parts included in the control unit 33 may be composed of electronic circuits.

[0103] Furthermore, it is not essential for the exhaust treatment system 3 to have at least some of its functions integrated into a single housing; the components of the exhaust treatment system 3 may be distributed across multiple housings. Conversely, functions that are distributed across multiple devices in Embodiment 1 may be integrated into a single housing.

[0104] Furthermore, at least a portion of the internal combustion engine system 100 is not limited to being mounted on the hull, but may be provided separately from the hull. For example, if the control unit 33 of the exhaust treatment system 3 is implemented by a server device provided separately from the hull, the control unit 33 can control the internal combustion engine system 100 through communication between the server device and the hull (its communication device). At least a portion of the functions of the control unit 33 may be realized by the cloud (cloud computing), etc.

[0105] Furthermore, the vessels on which the internal combustion engine system 100 is installed are not limited to large vessels such as ocean-going ships, but may also include, for example, small vessels used for sports or recreation at sea, such as "pleasure boats." In addition, the vessels on which the internal combustion engine system 100 is installed may include merchant ships, such as cargo ships and passenger-cargo ships, work vessels, such as tugboats and salvage ships, special vessels, such as weather observation ships and training ships, fishing boats, and warships. Moreover, the vessels are not limited to manned vessels with an operator on board, but may also be unmanned vessels that can be remotely operated by a person (operator) or that can operate autonomously. Furthermore, in addition to the engine body 2, the vessel may be equipped with one or more power sources such as motors (electric motors) in addition to the engine body 2. The internal combustion engine system 100 may also be used in applications other than vessels, such as work machinery, vehicles, or flying objects.

[0106] Furthermore, the engine body 2 is not limited to a gas engine that uses natural gas, mainly composed of methane, as fuel gas. Moreover, the regeneration fuel supplied to the exhaust path 25 by the regeneration unit 32 is not limited to diesel fuel, nor is it limited to hydrocarbon fuels in general.

[0107] Furthermore, it is not essential that the regeneration processing unit 32 has a two-fluid nozzle 321; the regeneration processing unit 32 may supply regeneration fuel to the exhaust path 25 using a single-fluid nozzle.

[0108] [Notes on the invention] The following is an overview of the invention extracted from the above-described embodiments. Note that each configuration and processing function described below can be selected and combined as desired.

[0109] <Note 1> A catalyst for purifying unburned components of the fuel gas contained in the exhaust gas discharged from the engine body, which is powered by the supply of fuel gas, A regeneration processing unit that supplies regenerative fuel to a position upstream of the catalyst in the direction of exhaust flow in the exhaust path through which the exhaust passes, burns the regenerative fuel in the catalyst to raise the temperature of the catalyst, thereby performing a regeneration process on the catalyst, The system includes a control unit that controls the operation of the regeneration processing unit based on the exhaust state, Exhaust treatment system.

[0110] <Note 2> The exhaust state includes at least one of the exhaust temperature, oxygen concentration, and flow velocity. The exhaust treatment system described in Appendix 1.

[0111] <Note 3> The system further includes a temperature sensor positioned within the exhaust path through which the exhaust passes and for measuring the temperature of the exhaust. Exhaust treatment system as described in Appendix 2.

[0112] <Note 4> The state of the exhaust is determined based on the output of a physical quantity sensor placed in the exhaust path through which the exhaust passes. Exhaust treatment system as described in Appendix 2 or 3.

[0113] <Note 5> The exhaust state is determined based on the flow rate of at least one of the air supplied to the engine body and the fuel gas. An exhaust treatment system as described in any of the appendices 2 to 4.

[0114] <Note 6> The control unit permits the regeneration process if the first time required from the supply of the regeneration fuel until autoignition is equal to or greater than the second time required from the supply of the regeneration fuel until it reaches the catalyst. An exhaust treatment system as described in any of the appendices 1 to 5.

[0115] <Note 7> The control unit determines the first time based on the volume of the exhaust path, and the temperature and oxygen concentration of the exhaust, and determines the second time based on the flow velocity of the exhaust. The exhaust treatment system described in Appendix 6.

[0116] <Note 8> The exhaust state includes a first parameter consisting of the oxygen concentration of the exhaust and a second parameter consisting of at least one of the temperature and flow velocity of the exhaust. The control unit, If the oxygen concentration is above a threshold, the control of the regeneration processing unit is determined based on both the first parameter and the second parameter. If the oxygen concentration is less than the threshold, the control of the regeneration processing unit is determined based only on the first parameter among the first and second parameters. An exhaust treatment system as described in any of the appendices 1 to 7.

[0117] <Note 9> The aforementioned playback processing unit, During the regeneration process, a gas is supplied in addition to the regeneration fuel to a position upstream of the catalyst in the exhaust flow direction in the exhaust path. The regeneration process is stopped by ceasing the supply of the regeneration fuel and continuing the supply of the gas. An exhaust treatment system as described in any of the appendices 1 to 8.

[0118] <Note 10> The aforementioned playback processing unit, During the regeneration process, a gas is supplied in addition to the regeneration fuel to a position upstream of the catalyst in the exhaust flow direction in the exhaust path. The regenerative fuel and the gas are supplied by a two-fluid spray from one or more nozzles. An exhaust treatment system as described in any of the appendices 1 to 9.

[0119] <Note 11> In the two-fluid spray described above, the particle size of the regenerative fuel is kept within the range of 40 μm to 220 μm, more preferably 60 to 120 μm, so that the evaporation of the regenerative fuel is completed within a predetermined range of the exhaust path. Exhaust treatment system as described in Appendix 10.

[0120] <Note 12> In the aforementioned two-fluid spray, the spray angle of the regenerative fuel is kept within a range of 15 degrees to 60 degrees so that the evaporation of the regenerative fuel is completed within a predetermined range of the exhaust path. Exhaust treatment system as described in Appendix 10 or 11.

[0121] <Note 13> In the aforementioned two-fluid spray, the angle between the central axes of each injection nozzle of the regenerative fuel is kept within a range of 20 degrees to 90 degrees so that the evaporation of the regenerative fuel is completed within a predetermined range of the exhaust path. An exhaust treatment system as described in any of Appendix 10 to 12.

[0122] <Note 14> Further comprising a partition portion that divides the exhaust path into two or more spaces, located upstream of the catalyst in the direction of exhaust flow in the exhaust path, An exhaust treatment system as described in any of the appendices 1 to 13.

[0123] <Note 15> The aforementioned fuel gas mainly consists of methane, An exhaust treatment system as described in any of the appendices 1 to 14.

[0124] <Note 16> An exhaust treatment system as described in any of Appendix 1 to 15, The engine body comprises, Internal combustion engine system. [Explanation of Symbols]

[0125] 2. Engine body 3. Exhaust Treatment System 25 Exhaust path 27 Partition Section 31 Catalyst 32. Playback Processing Unit 33 Control Unit 34. Sensors (temperature sensors, physical quantity sensors) 100 Internal Combustion Engine Systems T1 1st hour T2 2nd hour

Claims

1. A catalyst for purifying unburned components of the fuel gas contained in the exhaust gas discharged from the engine body, which is powered by the supply of fuel gas, A regeneration processing unit that supplies regenerative fuel to a position upstream of the catalyst in the direction of exhaust flow in the exhaust path through which the exhaust passes, burns the regenerative fuel in the catalyst to raise the temperature of the catalyst, thereby performing a regeneration process on the catalyst, The system includes a control unit that controls the operation of the regeneration processing unit based on the exhaust state, Exhaust treatment system.

2. The exhaust state includes at least one of the exhaust temperature, oxygen concentration, and flow velocity. The exhaust treatment system according to claim 1.

3. The system further includes a temperature sensor positioned within the exhaust path through which the exhaust passes and for measuring the temperature of the exhaust. The exhaust treatment system according to claim 2.

4. The state of the exhaust is determined based on the output of a physical quantity sensor placed in the exhaust path through which the exhaust passes. The exhaust treatment system according to claim 2 or 3.

5. The exhaust state is determined based on the flow rate of at least one of the air supplied to the engine body and the fuel gas. The exhaust treatment system according to claim 2 or 3.

6. The control unit permits the regeneration process if the first time required from the supply of the regeneration fuel until autoignition is equal to or greater than the second time required from the supply of the regeneration fuel until it reaches the catalyst. The exhaust treatment system according to any one of claims 1 to 3.

7. The control unit determines the first time based on the volume of the exhaust path, and the temperature and oxygen concentration of the exhaust, and determines the second time based on the flow velocity of the exhaust. The exhaust treatment system according to claim 6.

8. The exhaust state includes a first parameter consisting of the oxygen concentration of the exhaust and a second parameter consisting of at least one of the temperature and flow velocity of the exhaust. The control unit, If the oxygen concentration is above a threshold, the control of the regeneration processing unit is determined based on both the first parameter and the second parameter. If the oxygen concentration is less than the threshold, the control of the regeneration processing unit is determined based only on the first parameter among the first and second parameters. The exhaust treatment system according to any one of claims 1 to 3.

9. The aforementioned playback processing unit, During the regeneration process, a gas is supplied in addition to the regeneration fuel to a position upstream of the catalyst in the exhaust flow direction in the exhaust path. The regeneration process is stopped by ceasing the supply of the regeneration fuel and continuing the supply of the gas. The exhaust treatment system according to any one of claims 1 to 3.

10. The aforementioned playback processing unit, During the regeneration process, a gas is supplied in addition to the regeneration fuel to a position upstream of the catalyst in the exhaust flow direction in the exhaust path. The regenerative fuel and the gas are supplied by a two-fluid spray from one or more nozzles. The exhaust treatment system according to any one of claims 1 to 3.

11. In the aforementioned two-fluid spray, the particle size of the regenerative fuel is kept within the range of 40 μm to 220 μm so that the evaporation of the regenerative fuel is completed within a predetermined range of the exhaust path. The exhaust treatment system according to claim 10.

12. In the aforementioned two-fluid spray, the spray angle of the regenerative fuel is kept within a range of 15 degrees to 60 degrees so that the evaporation of the regenerative fuel is completed within a predetermined range of the exhaust path. The exhaust treatment system according to claim 10.

13. In the two-fluid spray described above, the angle between the central axes of each injection nozzle of the regenerative fuel is kept within a range of 20 degrees to 90 degrees so that the evaporation of the regenerative fuel is completed within a predetermined range of the exhaust path. The exhaust treatment system according to claim 10.

14. Further comprising a partition portion that divides the exhaust path into two or more spaces, located upstream of the catalyst in the direction of the exhaust flow in the exhaust path, The exhaust treatment system according to any one of claims 1 to 3.

15. The aforementioned fuel gas mainly consists of methane, The exhaust treatment system according to any one of claims 1 to 3.

16. An exhaust treatment system according to any one of claims 1 to 3, The engine body comprises, Internal combustion engine system.

17. A catalyst for purifying unburned components of the fuel gas contained in the exhaust gas discharged from the engine body, which is powered by the supply of fuel gas, A control method for an exhaust gas treatment system comprising: a regeneration processing unit that supplies regenerative fuel to a position upstream of the catalyst in the direction of exhaust gas flow in an exhaust path through which the exhaust gas passes, and burns the regenerative fuel in the catalyst to raise the temperature of the catalyst, thereby performing a regeneration process on the catalyst; The operation of the regeneration processing unit is controlled based on the state of the exhaust gas. A method for controlling an exhaust gas treatment system.

18. The control method for the exhaust treatment system according to claim 17, A control program to be executed by one or more processors.

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