Methane number estimation device, gas engine control device, and methane number estimation method

Abstract

To provide a methane number estimation device, a gas engine control device, and a methane number estimation method, which can estimate a methane number without using a special sensor during operation of a gas engine.SOLUTION: A methane number estimation device for estimating the methane number of gas fuel supplied to an object gas engine, includes: a first association information acquisition unit that acquires first association information in which ignition timing, knocking strength, and a methane number of supplied gas fuel in the gas engine are associated with each other in advance; an ignition timing acquisition unit that acquires object ignition timing which is the ignition timing in the object gas engine; a knocking strength acquisition unit that acquires object knocking strength which is the knocking strength in a cycle including the object ignition timing of the object gas engine; and a methane number estimation unit that estimates the methane number of the gas fuel supplied to a cylinder of the object gas engine from the object ignition timing and the object knocking strength, on the basis of the first association information.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to an apparatus for estimating the methane number of a gas fuel supplied to a gas engine, a gas engine control device including the methane number estimation apparatus, and a method for estimating the methane number. [Background technology]

[0002] For example, it is known that natural gas properties (e.g., methane number) vary depending on the source of the gas. Conventional control devices that control the operating state of gas engines have not been able to detect changes in the gas properties (e.g., methane number) of the gas fuel supplied to the gas engine. Therefore, when the gas properties of the gas fuel supplied to the gas engine change, such as when switching between gas fuels, the gas engine may fall outside its appropriate operating range, resulting in abnormal combustion such as knocking or misfire.

[0003] When using multiple gas fuels with different methane numbers in the above-mentioned gas engine, a valve is provided in the gas fuel supply system to supply only one of the multiple gas fuels to the gas engine to prevent mixing of the multiple gas fuels. When switching gas fuels, the gas engine is stopped, various parameters are changed to accommodate the new gas fuel, and then the gas engine is restarted. Since intermittent operation of a gas engine is undesirable from an efficiency standpoint, it is desirable to operate the gas engine continuously even when switching gas fuels.

[0004] One way to ensure continuous operation of a gas engine even when switching between gas fuels is to change the ignition timing of the gas fuel in the gas engine to a safer setting before switching between gas fuels. However, this may result in a decrease in the output and fuel economy of the gas engine. Therefore, it is desirable to obtain changes in the gas properties (e.g., methane number) of the gas fuel supplied to the gas engine. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6002235 Summary of the Invention [Problem to be solved by the invention]

[0006] Patent Document 1 discloses that the methane number is calculated based on values ​​detected by a calorimeter that detects the heat value of gas fuel supplied to a cylinder, or a gas chromatograph that detects the composition of gas fuel supplied to a cylinder, and the ignition timing is changed based on the calculated methane number. Because special sensors such as a calorimeter and gas chromatograph are not devices that are provided in ordinary gas engines, there is a risk that the installation and management of the special sensors will increase the manufacturing and management costs of the gas engine.

[0007] In view of the above-described circumstances, an object of at least one embodiment of the present disclosure is to provide a methane number estimation device, a gas engine control device, and a methane number estimation method that are capable of estimating a methane number without using a special sensor during operation of a gas engine. [Means for solving the problem]

[0008] An apparatus for estimating a methane number according to an embodiment of the present disclosure includes: A methane number estimation device that estimates the methane number of a gas fuel supplied to a target gas engine that is a gas engine having at least one cylinder, a first association information acquisition unit that acquires first association information in which the ignition timing, the knocking intensity, and the methane number of the supplied gas fuel are associated in advance in the gas engine; an ignition timing acquisition unit that acquires a target ignition timing, which is the ignition timing of the target gas engine; a knocking intensity acquisition unit that acquires a target knocking intensity, which is the knocking intensity in a cycle including the target ignition timing of the target gas engine; and a methane number estimation unit that estimates the methane number of the gas fuel supplied to the cylinder in the target gas engine from the target ignition timing and the target knocking intensity based on the first association information.

[0009] A control device for a gas engine according to an embodiment of the present disclosure includes: The methane number estimation device; and an ignition timing control unit configured to control a target ignition timing, which is the ignition timing of the target gas engine, in accordance with the methane number of the gas fuel estimated by the methane number estimation device.

[0010] A method for estimating a methane number according to an embodiment of the present disclosure includes: A method for estimating the methane number of a gas fuel supplied to a target gas engine, which is a gas engine having at least one cylinder, comprising: a first association information acquisition step unit that acquires first association information in which the ignition timing, the knocking intensity, and the methane number of the supplied gas fuel are associated in advance in the gas engine; an ignition timing acquisition step of acquiring a target ignition timing, which is the ignition timing of the target gas engine; a knocking intensity acquisition step of acquiring a target knocking intensity, which is the knocking intensity in a cycle including the target ignition timing of the target gas engine; and a methane number estimation step of estimating the methane number of the gas fuel supplied to the cylinder in the target gas engine from the target ignition timing and the target knocking intensity based on the first association information. [Effects of the Invention]

[0011] According to at least one embodiment of the present disclosure, there are provided a methane number estimation device, a gas engine control device, and a methane number estimation method that are capable of estimating a methane number during operation of a gas engine without using a special sensor. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic configuration diagram of an engine system including a gas engine control device according to an embodiment of the present disclosure. [Figure 2] FIG. 1 is a schematic configuration diagram of a gas fuel supply system according to an embodiment of the present disclosure. [Figure 3] FIG. 1 is a flow diagram of a method for estimating a methane number according to a first embodiment of the present disclosure. [Figure 4] FIG. 4 is an explanatory diagram for explaining the relationship between knocking intensity and ignition timing in one cylinder. [Figure 5] FIG. 1 is an explanatory diagram for explaining a method for estimating a methane number using a specific knocking intensity. [Figure 6] FIG. 4 is a flow diagram of a method for estimating a methane number according to a second embodiment of the present disclosure. [Figure 7] FIG. 1 is a diagram showing the relationship between the methane number and the calorific value of gas fuel for each production area. [Figure 8] FIG. 2 is a diagram showing the relationship between the engine load in a gas engine for each gas fuel and the gas supply amount of the gas fuel supplied to the gas engine. [Figure 9] FIG. 10 is a flow diagram of a method for estimating a methane number according to a third embodiment of the present disclosure. [Figure 10] FIG. 4 is a diagram showing a change in in-cylinder pressure with respect to a crank angle. [Figure 11] FIG. 2 is a diagram showing the relationship between the lower heating value and the methane number of a gas fuel. [Figure 12] 2 is an explanatory diagram for explaining the relationship between the methane number of a gas fuel supplied to a gas engine and the ignition timing of the gas engine. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, several embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present disclosure. For example, expressions expressing relative or absolute arrangement such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" not only express such an arrangement exactly, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained. For example, expressions such as "identical," "equal," and "homogeneous" that indicate that something is in an equal state not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained. For example, expressions representing shapes such as a square shape or a cylindrical shape not only represent shapes such as a square shape or a cylindrical shape in the strict geometric sense, but also represent shapes including uneven portions, chamfered portions, etc., to the extent that the same effect can be obtained. On the other hand, the expressions "comprise," "include," or "have" one element are not exclusive expressions that exclude the presence of other elements. Note that the same components will be denoted by the same reference numerals and the description thereof will be omitted.

[0014] (Engine System) FIG. 1 is a schematic configuration diagram of an engine system including a gas engine control device according to an embodiment of the present disclosure. A methane number estimation device 1 (1A, 1B, 1C) according to some embodiments is a device that estimates a target methane number MNt, which is the methane number of gas fuel supplied to a target gas engine 2t, which is a gas engine 2 having at least one cylinder 21. Here, the target gas engine 2t is a gas engine 2 for which the methane number of gas fuel supplied is to be estimated by the methane number estimation device 1. Hereinafter, parameters and the like targeted for the target gas engine 2t may be referred to by the word "target" or by the symbol t to distinguish them from gas engines 2 other than the target gas engine 2t.

[0015] In the illustrated embodiment, the methane number estimation device 1 is mounted on a control device 3 that performs operation control and combustion control of a gas engine 2. As shown in Fig. 1, the engine system 4 includes a target gas engine 2t, a target control device 3t that is a control device 3 for the target gas engine 2t, a gas fuel injection device (a combustion injection valve in the illustrated example) 41 configured to inject gas fuel into the inside of a cylinder 21 of the target gas engine 2t, a gas fuel supply system 5 (see Fig. 2) for supplying gas fuel to the gas fuel injection device 41, and an ignition device (a spark plug in the illustrated example) 42 that ignites a gas (air-fuel mixture) containing gas fuel inside the cylinder 21 of the target gas engine 2t.

[0016] In the illustrated embodiment, the target gas engine 2t has a plurality of cylinders 21. A gas fuel injection device 41 and an ignition device 42 are provided for each cylinder 21 individually.

[0017] The target gas engine 2t (2) is configured to generate power by burning gas fuel therein. In the illustrated embodiment, the engine system 4 further includes a generator 43 connected to the drive shaft 22 of the target gas engine 2t. The generator 43 is configured to receive the power generated by the target gas engine 2t via the drive shaft 22 and to generate electricity using the power transmitted from the target gas engine 2t.

[0018] (Measuring equipment installed in engine systems) The engine system 4 includes a knocking sensor 44 provided for each cylinder 21 of the target gas engine 2t(2) and an in-cylinder pressure sensor 45 provided for each cylinder 21 of the target gas engine 2t(2). The knocking sensor 44 and the in-cylinder pressure sensor 45 are measuring devices that are installed in a normal gas engine. The engine system 4 does not include any special sensors such as a calorimeter or gas chromatograph.

[0019] The knocking sensor 44 is configured to generate electricity in response to vibrations of the cylinder 21 to which it is attached. In one embodiment, the knocking sensor 44 generates electricity when a weight built into the sensor vibrates in response to vibrations of the cylinder 21 to which it is attached, and the vibration of the weight applies force to a piezoelectric element (piezoelectric ceramics). When knocking occurs, the vibrations are greater than normal, and the electrical force generated by the piezoelectric element increases. The amount of electricity generated by the knocking sensor 44 can be monitored by the target control device 3t (3) to detect whether knocking is occurring in the cylinder 21 to which the knocking sensor 44 is attached.

[0020] The in-cylinder pressure sensor 45 is configured to generate electricity according to the pressure inside the cylinder 21 to which it is attached. In one embodiment, the in-cylinder pressure sensor 45 uses a piezoelectric element, a strain gauge, or the like as a pressure detection element. By monitoring the amount of electricity generated by the in-cylinder pressure sensor 45 with the target control device 3t(3), it is possible to monitor the pressure inside the cylinder 21 to which the in-cylinder pressure sensor 45 is attached.

[0021] (Gas engine control device) The target control device 3t(3) is composed of an engine control unit for controlling the operation of each device provided in the engine system 4, such as the target gas engine 2t, the gas fuel injection device 41, and the ignition device 42. As shown in Fig. 1 , the target control device 3t(3) includes an engine control unit 31, a combustion control unit 32, a combustion diagnosis unit 33, a gas fuel supply amount control unit 34, an ignition timing control unit 35, and the methane number estimation device 1.

[0022] For example, information relating to the operation of the target gas engine 2t is sent from each device included in the engine system 4, such as the target gas engine 2t, to each part of the target control device 3t (3), such as the methane number estimation device 1. The information relating to the operation of the target gas engine 2t includes, for example, the rotation speed of the target gas engine 2t, the engine (generator 43) output, the engine (generator 43) load, the inlet pressure, the outlet pressure, the inlet temperature, the outlet temperature or the pressure ratio, the crank angle of the cylinder 21, the detection value of the knocking sensor 44, or the detection value of the in-cylinder pressure sensor 45.

[0023] The combustion diagnosis unit 33 is configured to be able to perform combustion diagnosis of each cylinder 21 in the target gas engine 2t based on information related to the operation of the target gas engine 2t, such as the detection value of the knocking sensor 44 and the detection value of the in-cylinder pressure sensor 45. The combustion control unit 32 is configured to determine the amount of gas fuel to be supplied to each cylinder 21 in the target gas engine 2t and the ignition timing of each cylinder 21 in the target gas engine 2t based on the results of the combustion diagnosis sent from the combustion diagnosis unit 33 and information sent from each part of the target control device 3t (3).

[0024] The gas fuel supply amount control unit 34 is configured to control the opening and closing of valves provided in the gas fuel supply system 5 and the gas fuel injection device 41 so that the supply amount of gas fuel determined in the combustion control unit 32 is supplied to each cylinder 21 of the target gas engine 2t. The ignition timing control unit 35 is configured to control the ignition timing of the ignition device 42 so that the ignition device 42 ignites at the ignition timing determined in the combustion control unit 32.

[0025] The engine control unit 31 is configured to control the operation and stop of the target gas engine 2t based on information relating to the operation of the target gas engine 2t and information sent from each unit of the target control device 3t (3).

[0026] (Gas fuel supply system) FIG. 2 is a schematic configuration diagram of a gas fuel supply system according to an embodiment of the present disclosure. As shown in Figure 2, the gas fuel supply system 5 comprises a first gas fuel storage device (in the illustrated example, a gas fuel storage tank) 51 for storing a first gas fuel, a second gas fuel storage device (in the illustrated example, a gas fuel storage tank) 52 for storing a second gas fuel having a different methane number than the first gas fuel, a first gas fuel supply line 53 for sending the first gas fuel from the first gas fuel storage device 51 to the target gas engine 2t (specifically, the gas fuel injection device 41 in the target gas engine 2t), a second gas fuel supply line 54 for sending the second gas fuel from the second gas fuel storage device 52 to the target gas engine 2t (specifically, the gas fuel injection device 41 in the target gas engine 2t), and a switching device 55 configured to be able to switch the source of the gas fuel sent to the target gas engine 2t between the first gas fuel storage device 51 and the second gas fuel storage device 52.

[0027] In the illustrated embodiment, the second gas fuel supply line 54 joins with the first gas fuel supply line 53 at a joining section 56. The switching device 55 includes a first valve 551 provided on the first gas fuel supply line 53 upstream of the joining section 56 (on the first gas fuel storage device 51 side), and a second valve 552 provided on the second gas fuel supply line 54 upstream of the joining section 56 (on the second gas fuel storage device 52 side). Each of the first valve 551 and the second valve 552 can adjust the flow rate of gas fuel supplied downstream of the valve body (on the target gas engine 2t side) by moving a valve body that opens and closes the gas fuel supply path.

[0028] In the embodiment shown in Fig. 2, the gas fuel stored in the first gas fuel storage device 51 consists of a first liquefied gas. The gas fuel stored in the second gas fuel storage device 52 consists of a second liquefied gas having a methane number different from that of the first liquefied gas. In the solid line area in Fig. 2, the gas fuel is in a liquid state, and in the dotted line area in Fig. 2, the gas fuel is in a gaseous state.

[0029] The first gas fuel supply line 53 includes a first liquefied gas supply line 533 for guiding the first liquefied gas extracted from the first gas fuel storage device 51 by the first pump 531 to the first valve 551 after vaporizing it in a first vaporization device 532, and a first boil-off gas supply line 534 for guiding the first boil-off gas formed by vaporizing the first liquefied gas in the first gas fuel storage device 51 to the first valve 551.

[0030] The second gas fuel supply line 54 includes a second liquefied gas supply line 543 for guiding the second liquefied gas extracted from the second gas fuel storage device 52 by the second pump 541 to the second valve 552 after vaporizing it in the second vaporization device 542, and a second boil-off gas supply line 544 for guiding the second boil-off gas vaporized from the second liquefied gas in the second gas fuel storage device 52 to the second valve 552.

[0031] (First methane number estimation method) FIG. 3 is a flow diagram of the method for estimating a methane number according to the first embodiment of the present disclosure. A methane number estimation method 100 according to some embodiments is a method for estimating the target methane number MNt. As shown in Fig. 3, the methane number estimation method 100 includes a first association information acquisition step S101, an ignition timing acquisition step S102, a knocking intensity acquisition step S103, and a methane number estimation step S104.

[0032] In the illustrated embodiment, several steps in the methane number estimation method 100 (first association information acquisition step S101, ignition timing acquisition step S102, knocking intensity acquisition step S103, and methane number estimation step S104) are performed by a methane number estimation device 1 (1A). The methane number estimation device 1 (1A) is configured to be able to execute the first association information acquisition step S101, ignition timing acquisition step S102, knocking intensity acquisition step S103, and methane number estimation step S104, and is configured to perform these steps. Note that several steps in the methane number estimation method 100 may be performed by a device or equipment other than the methane number estimation device 1 (1A), or may be performed manually.

[0033] In the first association information acquisition step S101, first association information AI1 is acquired, in which the ignition timing IT, the knocking intensity KI, and the methane number MN of the supplied gas fuel are associated in advance in the gas engine 2. In the illustrated embodiment, the first association information acquisition unit 11 executes the first association information acquisition step S101. The first association information AI1 is created in advance before the first association information acquisition step S101 and stored in the database unit 46. The first association information acquisition unit 11 acquires the first association information AI1 from the database unit 46.

[0034] 3, the database unit 46 is provided outside the methane number estimation device 1, but in some other embodiments, it may be provided inside the methane number estimation device 1. Furthermore, the database unit 46 may be provided inside the control device 3, or may be provided in a location remote from the gas engine 2 and the control device 3 and be capable of communicating with the methane number estimation device 1 via a network line or the like.

[0035] The first association information AI1 indicates the correspondence between the ignition timing IT in the gas engine 2, the knocking intensity KI in the gas engine 2, and the methane number MN of the gas fuel supplied to the gas engine 2, and when the ignition timing IT and the knocking intensity KI are used as input information, it is sufficient that the methane number MN corresponding to the input information, that is, the ignition timing IT and the knocking intensity KI, can be obtained as output information.

[0036] In the ignition timing acquisition step S102, a target ignition timing ITt, which is the ignition timing IT of the target gas engine 2t, is acquired. In the illustrated embodiment, the ignition timing acquisition unit 12 executes the ignition timing acquisition step S102. The ignition timing acquisition unit 12 acquires the target ignition timing ITt from the combustion control unit 32, the ignition timing control unit 35, or the like.

[0037] In the knocking intensity acquisition step S103, a target knocking intensity KIt, which is a knocking intensity KI in a cycle including a target ignition timing ITt of the target gas engine 2t, is acquired. In the illustrated embodiment, the knocking intensity acquisition unit 13 executes the knocking intensity acquisition step S103.

[0038] The target knocking intensity KIt is calculated by a known method using parameters that are generally measured in the engine system 4 (for example, the detection value of the knocking sensor 44 and the detection value of the in-cylinder pressure sensor 45). In one embodiment, the knocking intensity acquisition unit 13 acquires the detection value of the knocking sensor 44 and the detection value of the in-cylinder pressure sensor 45, and forms a waveform from the detection value of the knocking sensor 44, with the horizontal axis representing the crank angle and the vertical axis representing the pressure. The knocking intensity acquisition unit 13 removes low-frequency components from the waveform using the detection value of the in-cylinder pressure sensor 45, and then determines the maximum pressure amplitude in each cycle as the target knocking intensity KIt. Note that if the combustion diagnosis unit 33 calculates the target knocking intensity KIt, the knocking intensity acquisition unit 13 may acquire the target knocking intensity KIt calculated by the combustion diagnosis unit 33.

[0039] In the methane number estimation step S104, a target methane number MNt is estimated from the target ignition timing ITt and the target knocking intensity KIt based on the above-described first association information AI1. In the illustrated embodiment, the methane number estimation unit 14 executes the methane number estimation step S104. Specifically, the methane number estimation unit 14 estimates the target methane number MNt from the target ignition timing ITt acquired by the ignition timing acquisition unit 12 and the target knocking intensity KIt acquired by the knocking intensity acquisition unit 13 based on the first association information AI1 acquired by the first association information acquisition unit 11.

[0040] According to the above method, the target methane number MNt can be estimated from the target ignition timing ITt and the target knocking intensity KIt by using the first association information AI1 that indicates the relationship between the ignition timing IT, the knocking intensity KI, and the methane number MN of the supplied gas fuel in the gas engine 2. The ignition timing IT and the knocking intensity KI can be acquired from sensors that are normally attached to the target gas engine 2t while the target gas engine 2t is operating. Therefore, according to the above method, the target methane number MNt can be estimated while the target gas engine 2t is operating without using a special sensor such as a calorimeter.

[0041] In some embodiments, as shown in FIG. 3 , the above-described methane number estimation device 1 (1A) includes a first association information acquisition unit 11 that acquires the above-described first association information AI1, an ignition timing acquisition unit 12 that acquires the above-described target ignition timing ITt, a knocking intensity acquisition unit 13 that acquires the above-described target knocking intensity KIt in a cycle including the above-described target ignition timing ITt, and a methane number estimation unit 14 that estimates a target methane number MNt from the target ignition timing ITt and the target knocking intensity KIt based on the above-described first association information AI1.

[0042] According to the above configuration, the target methane number MNt can be estimated from the target ignition timing ITt and the target knocking intensity KIt by using the first association information AI1 that indicates the relationship between the ignition timing IT, the knocking intensity KI, and the methane number MN of the supplied gas fuel in the gas engine 2. The ignition timing IT and the knocking intensity KI can be acquired from sensors that are normally attached to the target gas engine 2t while the target gas engine 2t is operating. Therefore, according to the above configuration, the target methane number MNt can be estimated while the target gas engine 2t is operating without using a special sensor such as a calorimeter.

[0043] Fig. 4 is an explanatory diagram for explaining the relationship between knocking intensity and ignition timing in one cylinder, and Fig. 5 is an explanatory diagram for explaining a method for estimating the methane number using a specific knocking intensity. In some embodiments, as shown in FIG. 5 , under a constant load condition in which the target engine load ELt of the target gas engine 2t is constant, the above-mentioned methane number estimation unit 14 (methane number estimation step S104) estimates the methane number of the gas fuel supplied to the cylinder 21 in the target gas engine 2t (target methane number MNt) based on the first association information AI1 from the target knocking intensity KIt1 when a specific knocking intensity KIs is reached and the target ignition timing ITt1 in the cycle including the target knocking intensity KIt1 when the specific knocking intensity KIs is reached.

[0044] 4 shows the changes in knocking intensity KI and ignition timing IT over time T for one cylinder 21 under constant load conditions where the target engine load ELt of the target gas engine 2t is constant. As shown in FIG. 4, when the ignition timing IT is gradually advanced, the knocking intensity KI (amplitude width) gradually increases and exceeds a specific knocking intensity KIs.

[0045] 5 shows a graph in which the horizontal axis represents the ignition timing IT of one cylinder 21 of the target gas engine 2t and the vertical axis represents the knocking intensity KI of the one cylinder 21 under a constant load condition where the target engine load ELt of the target gas engine 2t is constant. The graph shows a first curve C1 showing the relationship between the ignition timing IT and the knocking intensity KI for a gas fuel having a first methane number, and a second curve C2 showing the relationship between the ignition timing IT and the knocking intensity KI for a gas fuel having a second methane number higher than the first methane number. The first curve C1 and the second curve C2 are included in the first association information AI1 described above.

[0046] As shown in FIG. 5, the above-described methane number estimation unit 14 (methane number estimation step S104) instructs the ignition timing control unit 35 to advance the target ignition timing ITt from the preset set ignition timing ITs in one cylinder 21 of the target gas engine 2t until the target knocking intensity KIt reaches a specific knocking intensity KIs.

[0047] The above-described methane number estimation unit 14 (methane number estimation step S104) determines the target knocking intensity KIt1 and the target ignition timing ITt1 in the cycle in which the target knocking intensity KIt reaches (exceeds) the specific knocking intensity KIs, as shown in Fig. 5. The above-described methane number estimation unit 14 (methane number estimation step S104) determines the proportion of the target ignition timing ITt1 from the ignition timing ITc1 at the specific knocking intensity KIs on the first curve C1 and the ignition timing ITc2 at the specific knocking intensity KIs on the second curve C2, and can calculate the target methane number MNt from the proportion of the target ignition timing ITt1, the first methane number, and the second methane number.

[0048] The higher the specific knocking intensity KIs is set, the greater the difference in the target ignition timing ITt for each gas fuel can be, which improves the accuracy of estimating the target methane number MNt, but there is a risk that the possibility of knocking occurring will increase. According to the above configuration, by estimating the target methane number MNt using the target knocking intensity KIt1 and the target ignition timing ITt1 in the cycle in which the specific knocking intensity KIs is reached, it is possible to increase the accuracy of estimating the target methane number MNt while suppressing knocking in the target gas engine 2t.

[0049] The target methane number MNt estimated by the methane number estimation unit 14 is sent to the combustion control unit 32. The combustion control unit 32 determines the ignition timing of each cylinder 21 in the target gas engine 2t based on the target methane number MNt estimated by the methane number estimation unit 14. The ignition timing control unit 35 is configured to control the ignition timing of the ignition device 42 so that the ignition device 42 ignites at the ignition timing determined by the combustion control unit 32 based on the target methane number MNt estimated by the methane number estimation unit 14. In other words, the ignition timing control unit 35 is configured to control the target ignition timing ITt in accordance with the target methane number MNt estimated by the methane number estimation unit 14.

[0050] In some embodiments, at least one of the methane number estimation device 1 and the control device 3 may reflect the target methane number MNt estimated by the methane number estimation unit 14 in one cylinder 21 of the target gas engine 2t in other cylinders 21 of the target gas engine 2t other than the one cylinder 21. In this case, it is possible to reduce the influence of changes in the performance of the target gas engine 2t when estimating the target methane number MNt.

[0051] In some embodiments, the methane number estimation device 1 may estimate the target methane number MNt for each cylinder 21 of the target gas engine 2t. In this case, since an appropriate target methane number MNt can be estimated for each cylinder 21, variation in combustion for each cylinder 21 can be suppressed.

[0052] (Second methane number estimation method) FIG. 6 is a flowchart of a method for estimating a methane number according to the second embodiment of the present disclosure. A methane number estimation method 200 according to some embodiments is a method for estimating the target methane number MNt. As shown in Fig. 6, the methane number estimation method 200 includes a second association information acquisition step S201, an engine load acquisition step S202, a gas supply amount acquisition step S203, and a methane number estimation step S204.

[0053] In the illustrated embodiment, several steps in the methane number estimation method 200 (second association information acquisition step S201, engine load acquisition step S202, gas supply amount acquisition step S203, and methane number estimation step S204) are performed by a methane number estimation device 1 (1B). The methane number estimation device 1 (1B) is configured to be able to execute the second association information acquisition step S201, engine load acquisition step S202, gas supply amount acquisition step S203, and methane number estimation step S204, and is configured to perform these steps. Note that several steps in the methane number estimation method 200 may be performed by a device or equipment other than the methane number estimation device 1 (1B), or may be performed manually.

[0054] In the second association information acquisition step S201, second association information AI2 is acquired, in which the engine load EL, the gas supply amount FS of the supplied gas fuel, and the methane number MN of the gas fuel are associated in advance in the gas engine 2. In the illustrated embodiment, the second association information acquisition unit 61 executes the second association information acquisition step S201. The second association information AI2 is created in advance before the second association information acquisition step S201 and is stored in the database unit 46. The second association information acquisition unit 61 acquires the second association information AI2 from the database unit 46.

[0055] The second association information AI2 indicates the correspondence between the engine load EL in the gas engine 2, the gas supply amount FS of the gas fuel supplied to the gas engine 2, and the methane number MN of the gas fuel supplied to the gas engine 2, and when the engine load EL and the gas supply amount FS are used as input information, it is sufficient that the methane number MN corresponding to the input information, that is, the engine load EL and the gas supply amount FS, can be obtained as output information.

[0056] Figure 7 is a diagram showing the relationship between the methane number and calorific value of gas fuel for each production area. Figure 7 shows a graph with calorific value on the horizontal axis and methane number on the vertical axis, and gas fuels are plotted on this graph for each production area. As shown in Figure 7, there is a tendency for the methane number to decrease as the calorific value increases.

[0057] FIG. 8 is a diagram showing the relationship between the engine load of a gas engine for each gas fuel and the gas supply amount of the gas fuel supplied to the gas engine. FIG. 8 shows a graph with the engine load of the gas engine on the horizontal axis and the gas supply amount of the gas fuel supplied to the gas engine on the vertical axis. The graph shows a first straight line SL1 showing the relationship between the engine load and the gas supply amount for a gas fuel having a first methane number, and a second straight line SL2 showing the relationship between the engine load and the gas supply amount for a gas fuel having a second methane number higher than the first methane number. As shown in FIG. 8, the gas supply amount tends to increase as the engine load increases.

[0058] Generally, as the calorific value increases, the gas supply amount tends to decrease. From the above, there is a certain correlation between the gas supply amount, the calorific value, and the methane number. As the calorific value increases, the gas supply amount and the methane number tend to decrease. The second association information AI2 includes information indicating the correlation between the gas supply amount, the calorific value, and the methane number.

[0059] In the engine load acquisition step S202, a target engine load ELt, which is the engine load EL of the target gas engine 2t, is acquired. In the illustrated embodiment, the engine load acquisition unit 62 executes the engine load acquisition step S202. The engine load acquisition unit 62 acquires the target engine load ELt from the target gas engine 2t, the generator 43 connected to the target gas engine 2t so as to be able to transmit power, sensors normally attached to the target gas engine 2t, the engine control unit 31, the combustion control unit 32, etc. Note that the engine load EL and the target engine load ELt may be the load of the generator connected to the gas engine 2t so as to be able to transmit power. In the engine load acquisition step S202, the load of the generator 43 described above may be acquired as the target engine load ELt.

[0060] In the gas supply amount acquisition step S203, a target gas supply amount FSt is acquired, which is the gas supply amount FS during the period in which the target engine load ELt of the target gas engine 2t is acquired. In the illustrated embodiment, the gas supply amount acquisition unit 63 executes the gas supply amount acquisition step S203. The gas supply amount acquisition unit 63 acquires the target gas supply amount FSt from the target gas engine 2t, sensors normally attached to the target gas engine 2t, the combustion control unit 32, the gas fuel supply amount control unit 34, etc.

[0061] In the methane number estimation step S204, a target methane number MNt is estimated from the target engine load ELt and the target gas supply rate FSt based on the above-described second association information AI2. In the illustrated embodiment, the methane number estimation unit 64 executes the methane number estimation step S204. Specifically, the methane number estimation unit 64 estimates the target methane number MNt from the target engine load ELt acquired by the engine load acquisition unit 62 and the target gas supply rate FSt acquired by the gas supply rate acquisition unit 63 based on the second association information AI2 acquired by the second association information acquisition unit 61.

[0062] According to the above method, the target methane number MNt can be estimated from the target engine load ELt and the target gas supply rate FSt by using the second association information AI2 that indicates the relationship between the engine load EL, the gas supply rate FS of the supplied gas fuel, and the methane number MN in the gas engine 2. The engine load EL and the gas supply rate FS can be acquired from sensors that are normally attached to the target gas engine 2t when the target gas engine 2t is operating. Therefore, according to the above method, the target methane number MNt can be estimated when the target gas engine 2t is operating without using a special sensor such as a calorimeter.

[0063] In some embodiments, as shown in FIG. 6 , the above-described methane number estimation device 1 (1B) includes a second association information acquisition unit 61 that acquires the above-described second association information AI2, an engine load acquisition unit 62 that acquires the above-described target engine load ELt, a gas supply amount acquisition unit 63 that acquires the target gas supply amount FSt during the period in which the above-described target engine load ELt was acquired, and a methane number estimation unit 64 that estimates a target methane number MNt from the target engine load ELt and the target gas supply amount FSt based on the above-described second association information AI2.

[0064] According to the above configuration, the target methane number MNt can be estimated from the target engine load ELt and the target gas supply rate FSt by using the second association information AI2 that indicates the relationship between the engine load EL, the gas supply rate FS of the supplied gas fuel, and the methane number MN in the gas engine 2. The engine load EL and the gas supply rate FS can be acquired from sensors that are normally attached to the target gas engine 2t when the target gas engine 2t is operating. Therefore, according to the above configuration, the target methane number MNt can be estimated when the target gas engine 2t is operating without using a special sensor such as a calorimeter.

[0065] (Third methane number estimation method) FIG. 9 is a flowchart of a method for estimating a methane number according to the third embodiment of the present disclosure. A methane number estimation method 300 according to some embodiments is a method for estimating the above-mentioned target methane number MNt. As shown in Fig. 9 , the methane number estimation method 300 includes a third association information acquisition step S301, a heat release amount acquisition step S302, a supply amount acquisition step S303, a lower heating value calculation step S304, and a methane number estimation step S305.

[0066] In the illustrated embodiment, several steps in the methane number estimation method 300 (third association information acquisition step S301, heat release amount acquisition step S302, supply amount acquisition step S303, lower heating value calculation step S304, and methane number estimation step S305) are performed by a methane number estimation device 1 (1C). The methane number estimation device 1 (1C) is configured to be able to execute the third association information acquisition step S301, heat release amount acquisition step S302, supply amount acquisition step S303, lower heating value calculation step S304, and methane number estimation step S305, and is configured to perform these steps. Note that several steps in the methane number estimation method 300 may be performed by a device or equipment other than the methane number estimation device 1 (1C), or may be performed manually.

[0067] In the third association information acquisition step S301, third association information AI3, in which the lower heating value LHV and the methane number MN of the supplied gas fuel are associated in advance, is acquired. In the illustrated embodiment, the third association information acquisition unit 71 executes the third association information acquisition step S301. The third association information AI3 is created in advance before the third association information acquisition step S301 and stored in the database unit 46. The third association information acquisition unit 71 acquires the third association information AI3 from the database unit 46.

[0068] The third association information AI3 indicates the correspondence between the lower heating value LHV of the gas engine 2 and the methane number MN of the gas fuel supplied to the gas engine 2, and when the lower heating value LHV is used as input information, it is sufficient that the methane number MN corresponding to the input information, the lower heating value LHV, can be obtained as output information.

[0069] In the heat release amount acquisition step S302, a target heat release amount QCt, which is the heat release amount QC per cycle in the target gas engine 2t, is acquired. In the illustrated embodiment, the heat release amount acquisition unit 72 executes the heat release amount acquisition step S302.

[0070] Fig. 10 is a diagram showing changes in in-cylinder pressure with respect to crank angle. Fig. 10 shows a graph with the crank angle θ on the horizontal axis and the in-cylinder pressure on the vertical axis. This graph shows a waveform PCA formed from the average value of the detection values ​​of the multiple in-cylinder pressure sensors 45 when gas fuel is combusted in the target gas engine 2t, and a waveform PCM formed from the detection values ​​of the in-cylinder pressure sensors 45 when gas fuel is not combusted in the target gas engine 2t.

[0071] The heat release amount acquisition unit 72 derives the target heat release amount QCt per cycle from the waveform formed from the detection value of the in-cylinder pressure sensor 45. The target heat release amount QCt per cycle can be derived by a known method from the change in in-cylinder pressure per cycle and the change in the internal volume of the cylinder 21. In one embodiment, the heat release rate for each crank angle θ is derived from the change in in-cylinder pressure per cycle and the change in internal volume of the cylinder 21, and the heat release rate for each crank angle θ is integrated to calculate the target heat release amount QCt per cycle.

[0072] In the supply amount acquisition step S303, a target supply amount MFt is acquired, which is the supply amount MF per cycle of gas fuel supplied to the target gas engine 2t during the period in which the target heat release amount QCt is acquired. In the illustrated embodiment, the supply amount acquisition unit 73 executes the supply amount acquisition step S303. The supply amount acquisition unit 73 acquires the target supply amount MFt from the target gas engine 2t, sensors normally attached to the target gas engine 2t, the combustion control unit 32, the gas fuel supply amount control unit 34, etc.

[0073] In the lower heating value calculation step S304, a target lower heating value LHVt, which is the lower heating value LHV of the target gas engine 2t, is calculated from the target heat release amount QCt and the target supply amount MFt. In the illustrated embodiment, the lower heating value calculation unit 74 executes the lower heating value calculation step S304.

[0074] In the illustrated embodiment, the lower heating value calculation unit 74 calculates the target lower heating value LHVt from the target heat generation amount QCt acquired by the heat generation amount acquisition unit 72 and the target supply amount MFt acquired by the supply amount acquisition unit 73 using the following equation (1): LHVt = (QCt+Qhl) / MFt (1) In addition, Qhl in the above formula (1) is the heat loss and may be a constant.

[0075] In addition, the low heating value calculation unit 74 may estimate the target low heating value LHVt calculated by the above formula (1) using a filter such as a Kalman filter, and use this as the target low heating value LHVt acquired by the low heating value calculation unit 74.

[0076] FIG. 11 is a diagram showing the relationship between the lower heating value LHV and the methane number of gas fuel. FIG. 11 is a graph with the lower heating value LHV on the horizontal axis and the methane number MN of the gas fuel on the vertical axis. This graph plots gas fuels by production area, and shows a regression line RL formed from the plots. As shown in FIG. 11, there is a tendency for the methane number to decrease as the lower heating value LHV increases.

[0077] In the methane number estimation step S305, a target methane number MNt is estimated from the target lower heating value LHVt based on the above-described third association information AI3. In the illustrated embodiment, the methane number estimation unit 75 executes the methane number estimation step S305. Specifically, the methane number estimation unit 75 estimates the target methane number MNt from the target lower heating value LHVt calculated by the lower heating value calculation unit 74 based on the third association information AI3 acquired by the third association information acquisition unit 71.

[0078] According to the above method, the target methane number MNt can be estimated from the target lower heating value LHVt by using the third association information AI3 that indicates the relationship between the lower heating value LHV and the methane number MN of the supplied gas fuel in the gas engine 2. The lower heating value LHV can be calculated from the amount of heat released QC and the amount of supply MF, which can be obtained from sensors that are normally attached to the target gas engine 2t when the target gas engine 2t is operating. Therefore, according to the above method, the target methane number MNt can be estimated when the target gas engine 2t is operating without using a special sensor such as a calorimeter.

[0079] In some embodiments, as shown in FIG. 9 , the methane number estimation device 1 (1C) described above includes a third association information acquisition unit 71 that acquires the third association information AI3 described above, a heat release amount acquisition unit 72 that acquires the target heat release amount QCt described above, a supply amount acquisition unit 73 that acquires the target supply amount MFt for the period during which the target heat release amount QCt was acquired, a lower heating value calculation unit 74 that calculates a target lower heating value LHVt from the target heat release amount QCt and the target supply amount MFt, and a methane number estimation unit 75 that estimates a target methane number MNt from the target lower heating value LHVt based on the third association information AI3 described above.

[0080] According to the above configuration, by using the third association information AI3 that indicates the relationship between the lower heating value LHV and the methane number MN of the supplied gas fuel in the gas engine 2, the target methane number MNt can be estimated from the target lower heating value LHVt. The lower heating value LHV can be calculated from the amount of heat released QC and the supply amount MF, which can be acquired from sensors that are normally attached to the target gas engine 2t when the target gas engine 2t is operating. Therefore, according to the above configuration, the target methane number MNt can be estimated when the target gas engine 2t is operating without using a special sensor such as a calorimeter.

[0081] Each of the first association information AI1, second association information AI2, and third association information AI3 includes a list, table, map, function, machine learning model, etc. that indicates the correspondence between the input information and the output information. Each of the first association information AI1, second association information AI2, and third association information AI3 may be created based on steady-state test data, or may be created based on past performance values, experimental values, numerical analysis results, etc. other than steady-state test data.

[0082] Each of the above-described first association information AI1, second association information AI2, and third association information AI3 may include not only information acquired from the target gas engine 2t, but also information acquired from gas engines 2 other than the target gas engine 2t. Furthermore, each of the first association information AI1, second association information AI2, and third association information AI3 may not include information acquired from the target gas engine 2t, but may include only information acquired from gas engines 2 other than the target gas engine 2t. In these cases, it is desirable that the gas engines 2 other than the target gas engine 2t from which information is acquired are the same model as or similar to the target gas engine 2t.

[0083] As shown in FIG. 1, a control device 3 for a gas engine 2 in some embodiments includes the above-described methane number estimation device 1 (1A, 1B, 1C) and an ignition timing control unit 35 configured to control the target ignition timing ITt, which is the ignition timing IT of a target gas engine 2t, in accordance with the target methane number MNt of the gas fuel estimated by the methane number estimation device 1.

[0084] Fig. 12 is an explanatory diagram for explaining the relationship between the methane number of the gas fuel supplied to the gas engine and the ignition timing of the gas engine. As shown in Fig. 12, if the methane number MN is high, the ignition timing IT can be advanced accordingly. When the target methane number MNt is high, the ignition timing control unit 35 advances the target ignition timing ITt accordingly, and when the target methane number MNt is low, the ignition timing control unit 35 retards the target ignition timing ITt accordingly, thereby enabling the target gas engine 2t to be operated with high efficiency.

[0085] According to the above configuration, the control device 3 of the gas engine 2 controls the target ignition timing ITt, which is the ignition timing IT of the target gas engine 2t, in the ignition timing control unit 35 in accordance with the methane number MNt of the gas fuel estimated by the methane number estimation device 1, thereby enabling combustion control of the target gas engine 2t in accordance with changes in the methane number of the gas fuel (target methane number MNt) supplied to the cylinder 21 of the target gas engine 2t. In this case, since the methane number MNt of the gas fuel can be continuously estimated and the target ignition timing ITt can be continuously adjusted when switching between gas fuels, continuous operation at high efficiency can be achieved without stopping the target gas engine 2t when switching between gas fuels.

[0086] The methane number estimation device 1 can estimate the target methane number when the supplied gas fuel is any of a mixed gas of a vaporized gas obtained by vaporizing a first liquefied gas and a first boil-off gas, a mixed gas of a vaporized gas obtained by vaporizing a second liquefied gas and a second boil-off gas, or a mixed gas of a vaporized gas obtained by vaporizing a first liquefied gas and a second liquefied gas. Therefore, the target gas engine 2t equipped with the above control device 3 can operate continuously with high efficiency even when the above-mentioned mixed gas is supplied as the gas fuel.

[0087] The present disclosure is not limited to the above-described embodiments, but also includes modifications to the above-described embodiments and appropriate combinations of these modifications.

[0088] The contents of the above-described embodiments can be understood, for example, as follows.

[0089] 1) The methane number estimation device (1A(1)) according to at least one embodiment of the present disclosure includes: A methane number estimation device (1A) that estimates the methane number (MNt) of a gas fuel supplied to a target gas engine (2t), which is a gas engine (2) having at least one cylinder (21), a first association information acquisition unit (11) that acquires first association information (AI1) in which an ignition timing (IT), a knocking intensity (KI), and a methane number (MN) of a supplied gas fuel are associated in advance in a gas engine (2); an ignition timing acquisition unit (12) that acquires a target ignition timing (ITt) that is the ignition timing (IT) in the target gas engine (2t); a knocking intensity acquisition unit (13) that acquires a target knocking intensity (KIt), which is the knocking intensity (KI) in a cycle including the target ignition timing (ITt) of the target gas engine (2t); and a methane number estimation unit (14) that estimates the methane number (MNt) of the gas fuel supplied to the cylinder (21) in the target gas engine (2t) from the target ignition timing (ITt) and the target knocking intensity (KIt) based on the first association information (AI1).

[0090] According to the configuration of 1) above, by using the first association information (AI1) indicating the relationship between the ignition timing (IT), knocking intensity (KI), and the methane number (MN) of the gas fuel supplied in the gas engine (2), it is possible to estimate the target methane number MNt (the methane number of the gas fuel supplied to the cylinder 21 in the target gas engine 2t) from the target ignition timing (ITt) and the target knocking intensity (KIt). The ignition timing (IT) and the knocking intensity (KI) can be acquired from sensors that are normally attached to the target gas engine (2t) while the target gas engine (2t) is operating. Therefore, according to the configuration of 1) above, it is possible to estimate the target methane number (MNt) while the target gas engine (2t) is operating without using a special sensor such as a calorimeter.

[0091] 2) In some embodiments, the methane number estimation device (1A) described in 1) above, The methane number estimation unit (14) Under a constant load condition where the engine load (ELt) of the target gas engine (2t) is constant, the methane number (MNt) of the gas fuel supplied to the cylinder (21) in the target gas engine (2t) is estimated based on the first association information (AI1) from the target knocking intensity (KIt1) when a specific knocking intensity is reached and the target ignition timing (ITt1) in a cycle including the target knocking intensity (KIt1) when the specific knocking intensity is reached.

[0092] The higher the specific knocking intensity is set, the greater the difference in target ignition timing (ITt1) for each gas fuel can be, which improves the accuracy of estimating the target methane number (MNt), but there is a risk that the possibility of knocking occurring will increase. According to the configuration of 2) above, by estimating the target methane number (MNt) using the target knocking intensity (KIt1) and the target ignition timing (ITt1) in the cycle in which the specific knocking intensity is reached, it is possible to increase the accuracy of estimating the target methane number (MNt) while suppressing knocking in the target gas engine (2t).

[0093] 3) The methane number estimation device (1B(1)) according to at least one embodiment of the present disclosure includes: A methane number estimation device (1B) that estimates the methane number (MNt) of a gas fuel supplied to a target gas engine (2t), which is a gas engine (2) having at least one cylinder (21), a second association information acquisition unit (61) that acquires second association information (AI2) in which an engine load (EL), a gas supply amount (FS) of the gas fuel to be supplied, and a methane number (MN) of the gas fuel are associated in advance in the gas engine (2); an engine load acquisition unit (62) that acquires a target engine load (ELt) that is the engine load (EL) of the target gas engine (2t); a gas supply amount acquisition unit (63) that acquires a target gas supply amount (FSt) that is the gas supply amount (FS) during a period in which the target engine load (ELt) of the target gas engine (2t) is acquired; and a methane number estimation unit (64) that estimates the methane number (MNt) of the gas fuel supplied to the cylinder (21) in the target gas engine (2t) from the target engine load (ELt) and the target gas supply amount (FSt) based on the second association information (AI2).

[0094] According to the configuration of 3) above, by using the second association information (AI2) indicating the relationship between the engine load (EL), the gas supply amount (FS) of the supplied gas fuel, and the methane number (MN) in the gas engine (2), the target methane number (MNt, the methane number of the gas fuel supplied to the cylinder 21 in the target gas engine 2t) can be estimated from the target engine load (ELt) and the target gas supply amount (FSt). The engine load (EL) and the gas supply amount (FS) can be acquired from sensors that are normally attached to the target gas engine (2t) when the target gas engine (2t) is operating. Therefore, according to the configuration of 3) above, the target methane number (MNt) can be estimated when the target gas engine (2t) is operating without using a special sensor such as a calorimeter.

[0095] 4) The methane number estimation device (1C(1)) according to at least one embodiment of the present disclosure includes: A methane number estimation device (1C) that estimates the methane number (MNt) of a gas fuel supplied to a target gas engine (2t), which is a gas engine (2) having at least one cylinder (21), a third association information acquisition unit (71) that acquires third association information (AI3) in which a lower heating value (LHV) of the gas engine (2) is associated in advance with a methane number (MN) of the gas fuel to be supplied; a heat release amount acquisition unit (72) that acquires a target heat release amount (QCt) that is a heat release amount (QC) per cycle in the target gas engine (2t); a supply amount acquisition unit (73) that acquires a target supply amount (MFt), which is a supply amount (MF) per cycle of gas fuel supplied to the target gas engine (2t) during a period in which the target heat release amount (QCt) is acquired; a lower heating value calculation unit (74) that calculates a target lower heating value (LHVt), which is a lower heating value (LHV) of the target gas engine (2t), from the target heat release rate (QCt) and the target supply rate (MFt); and a methane number estimation unit (75) that estimates the methane number (MNt) of the gas fuel supplied to the cylinder (21) in the target gas engine (2t) from the target lower heating value (LHVt) based on the third association information (AI3).

[0096] According to the configuration of 4) above, by using the third association information (AI3) indicating the relationship between the lower heating value (LHV) and the methane number (MN) of the gas fuel supplied in the gas engine (2), the target methane number (MNt, the methane number of the gas fuel supplied to the cylinder 21 in the target gas engine 2t) can be estimated from the target lower heating value (LHVt). The lower heating value (LHV) can be calculated from the amount of heat released (QC) and the amount of supply (MF), which can be obtained from a sensor or the like that is normally attached to the target gas engine (2t) when the target gas engine (2t) is operating. Therefore, according to the configuration of 4) above, the target methane number (MNt) can be estimated when the target gas engine (2t) is operating without using a special sensor such as a calorimeter.

[0097] 5) A control device (3) for a gas engine (2) according to at least one embodiment of the present disclosure, The methane number estimation device (1 (1A, 1B, 1C)) according to any one of 1) to 4) above, and an ignition timing control unit (35) configured to control a target ignition timing (ITt), which is the ignition timing (IT) of the target gas engine (2t), in accordance with the methane number (MNt) of the gas fuel estimated by the methane number estimation device (1).

[0098] According to the configuration of 5) above, the control device (3) for the gas engine (2) controls, in the ignition timing control unit (35), the target ignition timing (ITt), which is the ignition timing (IT) of the target gas engine (2t), in accordance with the methane number (MNt) of the gas fuel estimated by the methane number estimation device (1), thereby enabling combustion control of the target gas engine (2t) in accordance with changes in the methane number (MNt) of the gas fuel supplied to the cylinders (21) of the target gas engine (2t). In this case, the methane number (MNt) of the gas fuel can be continuously estimated and the target ignition timing (ITt) can be continuously adjusted when switching between gas fuels, thereby enabling continuous operation of the target gas engine (2t) at high efficiency without stopping the target gas engine (2t) when switching between gas fuels.

[0099] 6) A method (100) for estimating a methane number according to at least one embodiment of the present disclosure includes: A methane number estimation method (100) for estimating a methane number (MNt) of a gas fuel supplied to a target gas engine (2t), which is a gas engine (2) having at least one cylinder (21), comprising: a first association information acquisition step (S101) of acquiring first association information (AI1) in which an ignition timing (IT), a knocking intensity (KI), and a methane number (MN) of a supplied gas fuel are associated in advance in a gas engine (2); an ignition timing acquisition step (S102) of acquiring a target ignition timing (ITt) which is the ignition timing (IT) in the target gas engine (2t); a knocking intensity acquisition step (S103) of acquiring a target knocking intensity (KIt), which is the knocking intensity (KI) in a cycle including the target ignition timing (ITt) of the target gas engine (2t); and a methane number estimation step (S104) of estimating the methane number (MNt) of the gas fuel supplied to the cylinder (21) in the target gas engine (2t) from the target ignition timing (ITt) and the target knocking intensity (KIt) based on the first association information (AI1).

[0100] According to the method of 6) above, by using the first association information (AI1) indicating the relationship between the ignition timing (ITt), knocking intensity (KI) and the methane number (MN) of the gas fuel supplied in the gas engine (2), the methane number (target methane number MNt) of the gas fuel supplied to the cylinder (21) in the target gas engine (2t) can be estimated from the target ignition timing (ITt) and the target knocking intensity (KIt). The ignition timing (IT) and the knocking intensity (KI) can be acquired from sensors that are normally attached to the target gas engine (2t) while the target gas engine (2t) is operating. Therefore, according to the method of 6) above, the target methane number (MNt) can be estimated while the target gas engine (2t) is operating without using a special sensor such as a calorimeter.

[0101] 7) A method (200) for estimating a methane number according to at least one embodiment of the present disclosure includes: A methane number estimation method (200) for estimating a methane number (MNt) of a gas fuel supplied to a target gas engine (2t), which is a gas engine (2) having at least one cylinder (21), comprising: a second association information acquisition step (S201) of acquiring second association information (AI2) in which an engine load (EL), a gas supply amount (FS) of a gas fuel to be supplied, and a methane number (MN) of the gas fuel are associated in advance in a gas engine (2); an engine load acquisition step (S202) of acquiring a target engine load (ELt), which is the engine load (EL) in the target gas engine (2t); a gas supply amount acquisition step (S203) of acquiring a target gas supply amount (FSt) which is the gas supply amount (FS) during a period in which the target engine load (ELt) of the target gas engine (2t) is acquired; and a methane number estimation step (S204) of estimating the methane number (MNt) of the gas fuel supplied to the cylinder (21) in the target gas engine (2t) from the target engine load (ELt) and the target gas supply amount (FSt) based on the second association information (AI2).

[0102] According to the method of 7) above, by using the second association information (AI2) indicating the relationship between the engine load (EL), the gas supply amount (FS) of the supplied gas fuel, and the methane number (MN) in the gas engine (2), the target methane number (MNt, the methane number of the gas fuel supplied to the cylinder 21 in the target gas engine 2t) can be estimated from the target engine load (ELt) and the target gas supply amount (FSt). The engine load (EL) and the gas supply amount (FS) can be obtained from sensors that are normally attached to the target gas engine (2t) when the target gas engine (2t) is operating. Therefore, according to the method of 7) above, the target methane number (MNt) can be estimated when the target gas engine (2t) is operating without using a special sensor such as a calorimeter.

[0103] 8) A method (300) for estimating methane number according to at least one embodiment of the present disclosure includes: A methane number estimation method (300) for estimating a methane number (MNt) of a gas fuel supplied to a target gas engine (2t), which is a gas engine (2) having at least one cylinder (21), comprising: a third association information acquisition step (S301) of acquiring third association information (AI3) in which a lower heating value (LHV) of the gas engine (2) and a methane number (MN) of the supplied gas fuel are associated in advance; A heat release amount acquisition step (S302) of acquiring a target heat release amount (QCt) which is a heat release amount (QC) per cycle in the target gas engine (2t); A supply amount acquisition step (S303) for acquiring a target supply amount (MFt) which is a supply amount (MF) per cycle of gas fuel supplied to the target gas engine (2t) during the period in which the target heat release amount (QCt) is acquired; A lower heating value calculation step (S304) of calculating a target lower heating value (LHVt), which is the lower heating value (LHV) in the target gas engine (2t), from the target heat release rate (QCt) and the target supply rate (MFt); and a methane number estimation step (S305) of estimating the methane number (MNt) of the gas fuel supplied to the cylinder (21) in the target gas engine (2t) from the target lower heating value (LHVt) based on the third association information (AI1).

[0104] According to the method of 8) above, by using the third association information (AI3) indicating the relationship between the lower heating value (LHV) and the methane number (MN) of the gas fuel supplied in the gas engine (2), the target methane number (MNt, the methane number of the gas fuel supplied to the cylinder 21 in the target gas engine 2t) can be estimated from the target lower heating value (LHVt). The lower heating value (LHV) can be calculated from the heat release rate (QC) and the supply amount (MF), which can be obtained from sensors that are typically attached to the target gas engine (2t) when the target gas engine (2t) is operating. Therefore, according to the method of 8) above, the target methane number (MNt) can be estimated when the target gas engine (2t) is operating without using a special sensor such as a calorimeter. [Explanation of symbols]

[0105] 1,1A~1C Methane number estimation device 2 Gas engine 2t target gas engine 3. Control device 3t Target Control Device 4 Engine System 5 Gas fuel supply system 11 First association information acquisition unit 12 Ignition timing acquisition section 13 Knocking intensity acquisition unit 14 Methane number estimation section 21 cylinders 22 Drive shaft 31 Engine control unit 32 Combustion control unit 33 Combustion Diagnostics Department 34 Gas fuel supply amount control unit 35 Ignition timing control unit 41 Fuel injection valve 41 Gas fuel injection system 42 Ignition system 43 Generator 44 Knocking sensor 45 Cylinder pressure sensor 46 Database Department 51 First gas fuel storage device 52 Second gas fuel storage device 53 First gas fuel supply line 54 Second gas fuel supply line 55 Switching Device 56 Junction 61 Second association information acquisition unit 62 Engine load acquisition unit 63 Gas supply amount acquisition unit 64 Methane number estimation section 71 Third association information acquisition unit 72 Heat release amount acquisition unit 73 Supply amount acquisition section 74 Low-level heat generation calculation section 75 Methane number estimation section 100, 200, 300 Methane number estimation method AI1 First association information AI2 Second association information AI3 Third association information EL Engine Load ELt Target engine load FS gas supply amount FSt Target gas supply volume IT,ITc1,ITc2 Ignition timing ITs setting ignition timing ITt, ITt1 target ignition timing KI,KIs Knocking strength KIt, KIT1 Target knocking strength LHV Low Heating Value LHVt Target lower heating value MF supply volume MFt Target Supply MN Methane Number MNt Target methane number QC heat release QCt Target heat release S101: First association information acquisition step S102 Ignition timing acquisition step S103 Knocking strength acquisition step S104 Methane number estimation step S201: Second association information acquisition step S202 Engine load acquisition step S203 Gas supply amount acquisition step S204 Methane number estimation step S301: Third association information acquisition step S302 Heat release amount acquisition step S303 Supply amount acquisition step S304 Lower heating value calculation step S305 Methane number estimation step

Claims

1. A methane number estimation device that estimates the methane number of a gas fuel supplied to a target gas engine that is a gas engine having at least one cylinder, a first association information acquisition unit that acquires first association information in which the ignition timing, the knocking intensity, and the methane number of the supplied gas fuel are associated in advance in the gas engine; an ignition timing acquisition unit that acquires a target ignition timing, which is the ignition timing of the target gas engine; a knocking intensity acquisition unit that acquires a target knocking intensity, which is the knocking intensity in a cycle including the target ignition timing of the target gas engine; a methane number estimation unit that estimates a methane number of the gas fuel supplied to the cylinder in the target gas engine from the target ignition timing and the target knocking intensity based on the first association information, The first association information is information created as a table, map, function, or machine learning model based on data on ignition timing, knocking intensity, and methane number obtained under steady-state operating conditions of another gas engine that is the same as or similar to the target gas engine, or obtained by numerical analysis simulating the steady-state operating conditions. Methane number estimator.

2. The methane number estimation unit Under a constant load condition in which an engine load of the target gas engine is constant, a methane number of the gas fuel supplied to the cylinder of the target gas engine is estimated based on the first association information from the target knocking intensity when a specific knocking intensity is reached and the target ignition timing in a cycle including the target knocking intensity when the specific knocking intensity is reached. The methane number estimating device according to claim 1.

3. The methane number estimation device according to claim 1 or 2; an ignition timing control unit configured to control a target ignition timing, which is the ignition timing of the target gas engine, in accordance with the methane number of the gas fuel estimated by the methane number estimation device, Gas engine control device.

4. A method for estimating the methane number of a gas fuel supplied to a target gas engine, which is a gas engine having at least one cylinder, comprising: a first association information acquisition step of acquiring first association information in which the ignition timing, the knocking intensity, and the methane number of the supplied gas fuel are associated in advance in the gas engine; an ignition timing acquisition step of acquiring a target ignition timing, which is the ignition timing of the target gas engine; a knocking intensity acquisition step of acquiring a target knocking intensity, which is the knocking intensity in a cycle including the target ignition timing of the target gas engine; a methane number estimating step of estimating a methane number of the gas fuel supplied to the cylinder in the target gas engine from the target ignition timing and the target knocking intensity based on the first association information, The first association information is information created as a table, map, function, or machine learning model based on data on ignition timing, knocking intensity, and methane number obtained under steady-state operating conditions of another gas engine that is the same as or similar to the target gas engine, or obtained by numerical analysis simulating the steady-state operating conditions. Methods for estimating methane number.

Images