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

Abstract

To provide a methane number estimation device capable of estimating a methane number without using a special sensor during an operation of a gas engine, a control device for the gas engine and a methane number estimation method.SOLUTION: A methane number estimation device that estimates a methane number of gas fuel to be supplied to an object gas engine includes: a second association information acquisition section that acquires second association information in which an engine load, a gas supply amount of fuel gas to be supplied and a methane number of the gas fuel are beforehand associated with each other, in the gas engine; an engine load acquisition section that acquires an object engine load that is an engine load of the object gas engine; a gas supply amount acquisition section that acquires an object gas supply amount that is a gas supply amount in a period of acquisition of the object engine load of the object gas engine; and a methane number estimation section that estimates a methane number of the gas fuel supplied to a cylinder of the object gas engine from the object engine load and the object gas supply amount on the basis of the second association information.SELECTED DRAWING: Figure 6

Description

Technical Field

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

Background Art

[0002] For example, it is known that gas properties (e.g., methane number) differ depending on the production area of natural gas. A general control apparatus for controlling the operating state of a conventional gas engine has been unable to detect changes in the gas properties (e.g., methane number) of the gas fuel supplied to the gas engine. For this reason, when the gas properties of the gas fuel supplied to the gas engine change, such as when switching gas fuels, there is a risk of abnormal combustion such as knocking and misfire occurring outside the appropriate operating range of the gas engine.

[0003] In the above gas engine, when using a plurality of gas fuels having different methane numbers, a valve is provided in the gas fuel supply system so that the plurality of gas fuels are not confused, and only one of the plurality of gas fuels is supplied to the gas engine. When switching gas fuels, the gas engine was stopped, various parameters were changed to correspond to the new gas fuel, and then the gas engine was restarted. Since it is not preferable in terms of efficiency to intermittently operate the gas engine, it is desired to continuously operate the gas engine even when switching gas fuels.

[0004] As a measure for continuously operating the gas engine even when switching gas fuels, it is conceivable to change the ignition timing of the gas fuel in the gas engine to the safe side before switching the gas fuels. In this case, there is a risk of causing a decrease in the output and fuel consumption performance of the gas engine. Therefore, it is desired 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

Summary of the Invention

Problems to be Solved by the Invention

[0006] In Patent Document 1, the methane number is calculated based on detection values such as a calorimeter that detects the calorific value of the gaseous fuel supplied to the cylinder and a gas chromatograph that detects the composition of the gaseous fuel supplied to the cylinder, and the ignition timing is changed based on the calculated methane number. Since special sensors such as a calorimeter and a gas chromatograph are not equipment provided in a normal gas engine, there is a risk of increasing the manufacturing cost and management cost of the gas engine for the installation and management of special sensors.

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

Means for Solving the Problems

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

[0009] A control device for a gas engine according to an embodiment of the present disclosure The methane number estimation device; An ignition timing control unit configured to control a target ignition timing that is the ignition timing of the target gas engine according to the methane number of the gas fuel estimated by the methane number estimation device.

[0010] A method for estimating methane number according to an embodiment of the present disclosure A method for estimating the methane number of gas fuel supplied to a target gas engine, which is a gas engine including at least one cylinder, A first association information acquisition step of acquiring first association information in which the ignition timing, knocking intensity, and methane number of the gas fuel supplied in the gas engine are associated in advance; An ignition timing acquisition step of acquiring a target ignition timing that is the ignition timing in the target gas engine; A knocking intensity acquisition step of acquiring a target knocking intensity that is the knocking intensity in a cycle including the target ignition timing of the target gas engine; 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.

Advantages of the Invention

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

Brief Description of the Drawings

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Embodiments for Carrying Out the Invention

[0013] Hereinafter, some embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described as embodiments or shown in the drawings are not intended to limit the scope of the present disclosure thereto, but are merely illustrative examples. For example, expressions indicating relative or absolute arrangements such as "in a certain direction", "along a certain direction", "parallel", "orthogonal", "center", "concentric", or "coaxial" not only strictly represent such arrangements, but also represent states where there are tolerances or relative displacements with angles or distances that can achieve the same function. For example, expressions indicating that things are in an equal state such as "identical", "equal", and "homogeneous" not only strictly represent an equal state, but also represent states where there are tolerances or differences that can achieve the same function. For example, expressions indicating shapes such as a square shape or a cylindrical shape not only represent shapes such as a square shape or a cylindrical shape in a geometrically strict sense, but also represent shapes including uneven portions, chamfered portions, etc. within a range where the same effect can be obtained. On the other hand, expressions such as "comprising", "including", or "having" for one component are not exclusive expressions that exclude the existence of other components. Note that the same reference numerals may be given to similar configurations and the description may be omitted.

[0014] (Engine system) FIG. 1 is a schematic configuration diagram of an engine system including a control device for a gas engine according to an embodiment of the present disclosure. The 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 that is a gas engine 2 having at least one cylinder 21. Here, the target gas engine 2t is the target gas engine 2 for which the methane number of the gas fuel supplied by the methane number estimation device 1 is estimated. Hereinafter, for parameters and the like targeted at the target gas engine 2t, the word "target" or the symbol t may be attached 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 the 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 the control device 3 of the target gas engine 2t, a gas fuel injection device (in the illustrated example, a combustion injection valve) 41 configured to inject gas fuel into the inside of the cylinder 21 in 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 (in the illustrated example, an ignition plug) 42 that ignites a gas (air-fuel mixture) containing the gas fuel inside the cylinder 21 in the target gas engine 2t.

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

[0017] The target gas engine 2t (2) is configured to generate power by burning gas fuel inside. 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 such that the power generated by the target gas engine 2t is transmitted via the drive shaft 22 and electricity is generated by the power transmitted from the target gas engine 2t.

[0018] (Measuring instruments mounted on the engine system) The engine system 4 includes a knocking sensor 44 provided for each cylinder 21 of the target gas engine 2t (2) and a cylinder pressure sensor 45 provided for each cylinder 21 of the target gas engine 2t (2). The knocking sensor 44 and the cylinder pressure sensor 45 are measuring instruments mounted on a normal gas engine. The engine system 4 is not equipped with special sensors such as a calorimeter or gas chromatography.

[0019] The knocking sensor 44 is configured to generate electricity according to the vibration of the mounted cylinder 21. In a certain embodiment, the knocking sensor 44 has a weight built into the sensor that vibrates according to the vibration of the mounted cylinder 21, and electricity is generated when a force is applied to the piezoelectric element (piezoelectric ceramics) due to the vibration of the weight. Since the vibration becomes larger during knocking than during normal times, the electric force generated by the piezoelectric element increases. By monitoring the amount of electricity generated by the knocking sensor 44 with the target control device 3t(3), it is possible to detect the presence or absence of knocking in the cylinder 21 on which the knocking sensor 44 is mounted.

[0020] The in-cylinder pressure sensor 45 is configured to generate electricity according to the pressure inside the mounted cylinder 21. In a certain 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 on which the in-cylinder pressure sensor 45 is mounted.

[0021] (Control Device for Gas Engine) The target control device 3t(3) consists of an engine control unit for controlling the operation of each device included 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 above-mentioned methane number estimation device 1.

[0022] For example, information regarding 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 regarding the operation of the target gas engine 2t includes, for example, the rotational speed of the target gas engine 2t, the output of the engine (of the generator 43), the load of the engine (of the generator 43), 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, etc.

[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 regarding 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 supply amount of the gas fuel 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 result of the combustion diagnosis sent from the combustion diagnosis unit 33 and the 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 and gas fuel injection devices 41 provided in the gas fuel supply system 5 so that the supply amount of the gas fuel determined by the combustion control unit 32 is supplied to each cylinder 21 in 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 by 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 regarding the operation of the target gas engine 2t and the information sent from each part of the target control device 3t(3).

[0026] (Gas fuel supply system) Figure 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 includes a first gas fuel storage device (in the illustrated example, a gas fuel storage tank) 51 that stores a first gas fuel, a second gas fuel storage device (in the illustrated example, a gas fuel storage tank) 52 that stores a second gas fuel having a different methane number from 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 a target gas engine 2t (specifically, a 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 supply 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 merges with the first gas fuel supply line 53 at a merging portion 56. The switching device 55 includes a first valve 551 provided upstream of the merging portion 56 of the first gas fuel supply line 53 (on the side of the first gas fuel storage device 51), and a second valve 552 provided upstream of the merging portion 56 of the second gas fuel supply line 54 (on the side of the second gas fuel storage device 52). Each of the first valve 551 and the second valve 552 can adjust the flow rate of the gas fuel supplied to the downstream side (the side of the target gas engine 2t) of the valve body by moving a valve body that opens and closes the gas fuel supply path.

[0028] In the embodiment shown in Figure 2, the gas fuel stored in the first gas fuel storage device 51 is composed of a first liquefied gas. The gas fuel stored in the second gas fuel storage device 52 is composed of a second liquefied gas having a different methane number from the first liquefied gas. In the solid line portion in Figure 2, the gas fuel is in a liquid state, and in the dotted line portion in Figure 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 the first liquefied gas in the first vaporizer 532, and a first boil-off gas supply line 534 for guiding the first boil-off gas obtained 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 the second liquefied gas in the second vaporizer 542, and a second boil-off gas supply line 544 for guiding the second boil-off gas obtained by vaporizing the second liquefied gas in the second gas fuel storage device 52 to the second valve 552.

[0031] (First Estimation Method of Methane Number) FIG. 3 is a flowchart of a method for estimating the methane number according to the first embodiment of the present disclosure. The methane number estimation method 100 according to some embodiments is a method for estimating the target methane number MNt described above. 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, some steps (the first associated information acquisition step S101, the ignition timing acquisition step S102, the knocking intensity acquisition step S103, and the methane number estimation step S104) in the methane number estimation method 100 are performed by the methane number estimation device 1 (1A). The methane number estimation device 1 (1A) is configured to be able to execute the first associated information acquisition step S101, the ignition timing acquisition step S102, the knocking intensity acquisition step S103, and the methane number estimation step S104, and is adapted to perform these steps. Note that some steps in the methane number estimation method 100 may be performed by devices or equipment other than the methane number estimation device 1 (1A), or may be performed manually.

[0033] In the first associated information acquisition step S101, the first associated information AI1 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 is acquired. In the illustrated embodiment, the first associated information acquisition unit 11 executes the first associated information acquisition step S101. The first associated information AI1 is created in advance before the first associated information acquisition step S101 and stored in the database unit 46. The first associated information acquisition unit 11 acquires the first associated information AI1 from the database unit 46.

[0034] In the embodiment shown in FIG. 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. Further, the database unit 46 may be provided inside the control device 3, or may be provided at a remote location from the gas engine 2 or the control device 3 and be communicable with the methane number estimation device 1 via a network line or the like.

[0035] The first associated information AI1 shows the correspondence relationship among 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. 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, i.e., the ignition timing IT and the knocking intensity KI, can be obtained as output information.

[0036] In the ignition timing acquisition step S102, the target ignition timing ITt, which is the ignition timing IT in 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, etc.

[0037] In the knocking intensity acquisition step S103, the target knocking intensity KIt, which is the knocking intensity KI in the cycle including the 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 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 an 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 with the crank angle as the horizontal axis and the pressure as the vertical axis from the detection value of the knocking sensor 44. The knocking intensity acquisition unit 13 sets the maximum pressure amplitude in each cycle after removing the low-frequency component using the detection value of the in-cylinder pressure sensor 45 from the above waveform as the target knocking intensity KIt. When 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 value estimation step S104, based on the above-described first association information AI1, the target methane value MNt is estimated from the target ignition timing ITt and the target knocking intensity KIt. In the illustrated embodiment, the methane value estimation unit 14 executes the methane value estimation step S104. Specifically, the methane value estimation unit 14 estimates the target methane value 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, by using the first association information AI1 indicating the relationship between the ignition timing IT, the knocking intensity KI, and the methane value MN of the gas fuel supplied in the gas engine 2, the target methane value MNt 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 normally mounted on the target gas engine 2t during the operation of the target gas engine 2t. Therefore, according to the above method, the target methane value MNt can be estimated without using a special sensor such as a calorimeter during the operation of the target gas engine 2t.

[0041] In some embodiments, as shown in FIG. 3, the above-described methane value 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 target knocking intensity KIt in a cycle including the above-described target ignition timing ITt, and a methane value estimation unit 14 that estimates the target methane value 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, by using the first association information AI1 showing the relationship between the ignition timing IT, the knocking intensity KI, and the methane number MN of the gas fuel supplied in the gas engine 2, the target methane number MNt 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 obtained from sensors normally mounted on the target gas engine 2t during the operation of the target gas engine 2t. Therefore, according to the above configuration, it is possible to estimate the target methane number MNt without using a special sensor such as a calorimeter during the operation of the target gas engine 2t.

[0043] FIG. 4 is an explanatory diagram for explaining the relationship between the knocking intensity and the ignition timing in one cylinder. FIG. 5 is an explanatory diagram for explaining a method of estimating the methane number using a specific knocking intensity. In some embodiments, as shown in FIG. 5, the methane number estimation unit 14 (methane number estimation step S104) described above estimates the methane number (target methane number MNt) of the gas fuel supplied to the cylinder 21 in the target gas engine 2t 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, under a constant load condition where the target engine load ELt of the target gas engine 2t is constant.

[0044] FIG. 4 shows the changes in the knocking intensity KI and the ignition timing IT with respect to the passage of time T of one cylinder 21 under a constant load condition 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] In FIG. 5, under a constant load condition where the target engine load ELt of the target gas engine 2t is constant, a graph is shown with the ignition timing IT of one cylinder 21 of the target gas engine 2t on the horizontal axis and the knocking intensity KI of the above-mentioned one cylinder 21 on the vertical axis. In the above graph, a first curve C1 showing the relationship between the ignition timing IT and the knocking intensity KI in 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 in a gas fuel having a second methane number higher than the first methane number are shown. The first curve C1 and the second curve C2 are included in the above-mentioned first association information AI1.

[0046] As shown in FIG. 5, the above-mentioned 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 a preset set ignition timing ITs until the target knocking intensity KIt reaches a specific knocking intensity KIs in one cylinder 21 of the target gas engine 2t.

[0047] As shown in FIG. 5, the above-mentioned methane number estimation unit 14 (methane number estimation step S104) obtains the target knocking intensity KIt1 and the target ignition timing ITt1 in a cycle in which the target knocking intensity KIt has reached (exceeded) the specific knocking intensity KIs. The above-mentioned methane number estimation unit 14 (methane number estimation step S104) obtains the ratio of the target ignition timing ITt1 from the ignition timing ITc1 at the specific knocking intensity KIs of the first curve C1 and the ignition timing ITc2 at the specific knocking intensity KIs of the second curve C2, and can calculate the target methane number MNt from the ratio 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 made, so that the estimation accuracy of the target methane number MNt can be improved. However, there is a risk that knocking is more likely to occur. 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 when the specific knocking intensity KIs is reached, it is possible to suppress knocking in the target gas engine 2t and increase the estimation accuracy of the target methane number MNt.

[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. That is, the ignition timing control unit 35 is configured to control the target ignition timing ITt according to 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 or 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 to the other cylinders 21 other than the above one cylinder 21 of the target gas engine 2t. In this case, the influence of the performance change of the target gas engine 2t when estimating the target methane number MNt can be reduced.

[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, the variation in combustion for each cylinder 21 can be suppressed.

[0052] (Second method for estimating methane number) FIG. 6 is a flowchart of a method for estimating methane number according to a second embodiment of the present disclosure. The method 200 for estimating methane number according to some embodiments is a method for estimating the target methane number MNt described above. As shown in FIG. 6, the method 200 for estimating methane number 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, some steps (the second association information acquisition step S201, the engine load acquisition step S202, the gas supply amount acquisition step S203, and the methane number estimation step S204) in the method 200 for estimating methane number are performed by the 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, the engine load acquisition step S202, the gas supply amount acquisition step S203, and the methane number estimation step S204, and is adapted to perform these steps. Note that some steps in the method 200 for estimating methane number may be performed by devices 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, the second association information AI2 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 is acquired. 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 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 shows the correspondence relationship among 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. As long as the methane number MN corresponding to the engine load EL and the gas supply amount FS as input information can be obtained as output information when the engine load EL and the gas supply amount FS are used as input information.

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

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

[0058] Generally, as the calorific value increases, the gas supply amount tends to decrease. From the above, there is a certain correlation among 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 showing the correlation among the gas supply amount, the calorific value, and the methane number.

[0059] In the engine load acquisition step S202, the 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 that is power-transmittably connected to the target gas engine 2t, the sensors normally mounted on the target gas engine 2t, the engine control unit 31, the combustion control unit 32, and the like. Note that the engine load EL and the target engine load ELt may be the load of the generator power-transmittably connected to the gas engine 2. 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, the target gas supply amount FSt, which is the gas supply amount FS during the period when the target engine load ELt of the target gas engine 2t is acquired, 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, the sensors normally mounted on the target gas engine 2t, the combustion control unit 32, the gas fuel supply amount control unit 34, and the like.

[0061] In the methane number estimation step S204, the target methane number MNt is estimated from the target engine load ELt and the target gas supply amount FSt based on the second association information AI2 described above. 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 amount FSt acquired by the gas supply amount 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, by using the second association information AI2 indicating the relationship between the engine load EL, the gas supply amount FS of the gas fuel supplied, and the methane number MN in the gas engine 2, the target methane number MNt 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 normally mounted on the target gas engine 2t during the operation of the target gas engine 2t. Therefore, according to the above method, the target methane number MNt can be estimated without using a special sensor such as a calorimeter during the operation of the target gas engine 2t.

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

[0064] According to the above configuration, by using the second association information AI2 indicating the relationship between the engine load EL, the gas supply amount FS of the gas fuel supplied, and the methane number MN in the gas engine 2, the target methane number MNt 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 normally mounted on the target gas engine 2t during the operation of the target gas engine 2t. Therefore, according to the above configuration, the target methane number MNt can be estimated without using a special sensor such as a calorimeter during the operation of the target gas engine 2t.

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

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

[0067] In the third association information acquisition step S301, the third association information AI3 in which the lower calorific value LHV and the methane value 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 is 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 shows the correspondence between the lower heating value LHV in the gas engine 2 and the methane number MN of the gas fuel supplied to the gas engine 2. As long as the methane number MN corresponding to the input information, i.e., the lower heating value LHV, can be obtained as output information when the lower heating value LHV is used as the input information.

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

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

[0071] The heat generation amount acquisition unit 72 derives the target heat generation amount QCt per cycle from the waveform formed from the detection values of the in-cylinder pressure sensors 45. The target heat generation amount QCt per cycle can be derived by a known method from the change in the in-cylinder pressure per cycle and the change in the volume of the cylinder 21. In a certain embodiment, the heat generation rate for each crank angle θ is derived from the change in the in-cylinder pressure per cycle and the change in the volume of the cylinder 21, and the target heat generation amount QCt per cycle is calculated by integrating the heat generation rate for each crank angle θ.

[0072] In the supply amount acquisition step S303, the target supply amount MFt, which is the supply amount per cycle of the gas fuel supplied to the target gas engine 2t during the period when the target heat generation amount QCt is acquired, 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, and the like.

[0073] In the lower heating value calculation step S304, the target lower heating value LHVt, which is the lower heating value of the target gas engine 2t, is calculated from the target heat generation 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 formula (1). LHVt = (QCt+Qhl) / MFt ···(1) Note that Qhl in the above formula (1) is a heat loss and may be a constant.

[0075] Note that the lower heating value calculation unit 74 may use the target lower heating value LHVt estimated using a filter such as a Kalman filter for the target lower heating value LHVt calculated by the above formula (1) as the target lower heating value LHVt acquired by the lower heating value calculation unit 74.

[0076] FIG. 11 is a diagram showing the relationship between the lower heating value and the methane number of the gas fuel. In FIG. 11, it 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. Gas fuels for each production area are plotted on this graph, and a regression line RL formed from the plots is shown. As shown in FIG. 11, as the lower heating value LHV increases, the methane number tends to decrease.

[0077] In the methane value estimation step S305, based on the above-described third association information AI3, the target methane value MNt is estimated from the target lower heating value LHVt. In the illustrated embodiment, the methane value estimation unit 75 executes the methane value estimation step S305. Specifically, the methane value estimation unit 75 estimates the target methane value 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, by using the third association information AI3 indicating the relationship between the lower heating value LHV and the methane value MN of the gas fuel supplied in the gas engine 2, the target methane value MNt can be estimated from the target lower heating value LHVt. The lower heating value LHV can be calculated from the heat generation amount Qc and the supply amount MF, which can be obtained from sensors normally mounted on the target gas engine 2t during the operation of the target gas engine 2t. Therefore, according to the above method, the target methane value MNt can be estimated without using a special sensor such as a calorimeter during the operation of the target gas engine 2t.

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

[0080] According to the above configuration, 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 can be estimated from the target lower heating value LHVt. The lower heating value LHV can be calculated from the heat generation amount QC and the supply amount MF, which can be obtained from sensors normally attached to the target gas engine 2t during the operation of the target gas engine 2t. Therefore, according to the above configuration, it is possible to estimate the target methane number MNt without using a special sensor such as a calorimeter during the operation of the target gas engine 2t.

[0081] Each of the above-described first association information AI1, second association information AI2, and third association information AI3 includes a list, table, map, function, machine learning model, etc. indicating the correspondence between the above input information and the above output information. Each of the first association information AI1, second association information AI2, and third association information AI3 may be created based on steady test data, or may be created based on past performance values, experimental values, numerical analysis results, etc. other than steady 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 obtained from the target gas engine 2t but also information obtained from gas engines 2 other than the target gas engine 2t. Also, each of the first association information AI1, second association information AI2, and third association information AI3 may include only information obtained from gas engines 2 other than the target gas engine 2t without including information obtained from the target gas engine 2t. In these cases, it is desirable that the gas engine 2 other than the target gas engine 2t from which information is obtained be of the same model or a similar model as the target gas engine 2t.

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

[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 becomes high, the ignition timing control unit 35 advances the target ignition timing ITt accordingly, and when the target methane number MNt becomes low, the target ignition timing ITt is retarded accordingly, so that the target gas engine 2t can be operated with high efficiency.

[0085] According to the above configuration, the control device 3 for the gas engine 2 controls the target ignition timing ITt which is the ignition timing IT of the target gas engine 2t according to the methane number MNt of the gas fuel estimated by the methane number estimation device 1 in the ignition timing control unit 35, so that the combustion control of the target gas engine 2t can be performed according to the change in the methane number (target methane number MNt) of the gas fuel supplied to the cylinder 21 in the target gas engine 2t. In this case, since the methane number MNt of the gas fuel is continuously estimated at the time of switching the gas fuel and the target ignition timing ITt is continuously adjusted, it is possible to perform continuous operation with high efficiency without stopping the target gas engine 2t at the time of switching the gas fuel.

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

[0087] The present disclosure is not limited to the above-described embodiments, and includes forms obtained by modifying the above-described embodiments and forms obtained by appropriately combining these forms.

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

[0089] 1) The methane number estimation device (1A(1)) according to at least one embodiment of the present disclosure is a methane number estimation device (1A) that estimates the methane number (MNt) of gas fuel supplied to a target gas engine (2t) that is a gas engine (2) including 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 the supplied gas fuel are associated in advance in the 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) that is the knocking intensity (KI) in a cycle including the target ignition timing (ITt) of the target gas engine (2t); Based on the first association information (AI1), 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).

[0090] According to the configuration of 1) above, by using the first association information (AI1) showing the relationship between the ignition timing (IT), the knocking intensity (KI), 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 ignition timing (ITt) and the target knocking intensity (KIt). The ignition timing (IT) and the knocking intensity (KI) can be obtained from sensors normally mounted on the target gas engine (2t) during the operation of the target gas engine (2t). Therefore, according to the configuration of 1) above, the target methane number (MNt) can be estimated without using a special sensor such as a calorimeter during the operation of the target gas engine (2t).

[0091] 2) In some embodiments, it is the methane number estimation device (1A) described in 1) above, The methane number estimation unit (14) is 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 the cycle including the target knocking intensity (KIt1) when the specific knocking intensity is reached, 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.

[0092] The higher the specific knocking intensity is set, the greater the difference in the target ignition timing (ITt1) for each gas fuel can be, so the estimation accuracy of the target methane number (MNt) can be improved, but there is a risk that knocking is more likely to occur. 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 when a specific knocking intensity is reached, it is possible to suppress knocking in the target gas engine (2t) and make the estimation accuracy of the target methane number (MNt) high.

[0093] 3) The methane number estimation device (1B(1)) according to at least one embodiment of the present disclosure is 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) including 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 supplied, and the 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) which is the engine load (EL) in the target gas engine (2t); a gas supply amount acquisition unit (63) that acquires a target gas supply amount (FSt) which is the gas supply amount (FS) during the period when 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 gas fuel supplied, 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 normally installed in the target gas engine (2t) during the operation of the target gas engine (2t). Therefore, according to the configuration of 3) above, it is possible to estimate the target methane number (MNt) without using a special sensor such as a calorimeter during the operation of the target gas engine (2t).

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

[0096] According to the configuration of 4) above, by using the third association information (AI3) showing 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 generation amount (QC) and the supply amount (MF) that can be obtained from sensors normally mounted on the target gas engine (2t) during the operation of the target gas engine (2t). Therefore, according to the configuration of 4) above, it is possible to estimate the target methane number (MNt) without using a special sensor such as a calorimeter during the operation of the target gas engine (2t).

[0097] 5) The control device (3) of the 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 An ignition timing control unit (35) configured to control the target ignition timing (ITt), which is the ignition timing (IT) of the target gas engine (2t), according to the methane number (MNt) of the gas fuel estimated by the methane number estimation device (1).

[0098] According to the configuration of the above (5), 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), according to the methane number (MNt) of the gas fuel estimated by the methane number estimator (1) in the ignition timing control unit (35). Thus, combustion control of the target gas engine (2t) according to changes in the methane number (MNt) of the gas fuel supplied to the cylinder (21) in the target gas engine (2t) becomes possible. In this case, since the methane number (MNt) of the gas fuel is continuously estimated and the target ignition timing (ITt) is continuously adjusted when switching the gas fuel, continuous operation with high efficiency is possible without stopping the target gas engine (2t) when switching the gas fuel.

[0099] 6) The methane number estimation method (100) according to at least one embodiment of the present disclosure is a methane number estimation method (100) for estimating the methane number (MNt) of the gas fuel supplied to a target gas engine (2t), which is a gas engine (2) including at least one cylinder (21), a first association information acquisition step (S101) of acquiring first association information (AI1) in which the ignition timing (IT), knocking intensity (KI), and methane number (MN) of the gas fuel supplied in the gas engine (2) are associated in advance; 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) showing the relationship between the ignition timing (ITt), the 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 obtained from sensors normally mounted on the target gas engine (2t) during the operation of the target gas engine (2t). Therefore, according to the method of 6) above, the target methane number (MNt) can be estimated without using a special sensor such as a calorimeter during the operation of the target gas engine (2t).

[0101] 7) The methane number estimation method (200) according to at least one embodiment of the present disclosure is a methane number estimation method (200) for estimating the methane number (MNt) of gas fuel supplied to a target gas engine (2t) which is a gas engine (2) including at least one cylinder (21), a second association information acquisition step (S201) of acquiring second association information (AI2) in which the engine load (EL), the gas supply amount (FS) of the gas fuel supplied, and the methane number (MN) of the gas fuel are associated in advance in the 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 the period when 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) showing the relationship between the engine load (EL), the gas supply amount (FS) of the gas fuel to be supplied, 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 normally mounted on the target gas engine (2t) during the operation of the target gas engine (2t). Therefore, according to the method of (7) above, the target methane number (MNt) can be estimated without using a special sensor such as a calorimeter during the operation of the target gas engine (2t).

[0103] 8) The methane number estimation method (300) according to at least one embodiment of the present disclosure is a methane number estimation method (300) for estimating the methane number (MNt) of the 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 step (S301) of acquiring third association information (AI3) in which the lower heating value (LHV) and the methane number (MN) of the gas fuel to be supplied are associated in advance in the gas engine (2); a heat generation amount acquisition step (S302) of acquiring a target heat generation amount (QCt) which is the heat generation amount per cycle in the target gas engine (2t); a supply amount acquisition step (S303) of acquiring a target supply amount (MFt) which is the supply amount per cycle of the gas fuel supplied to the target gas engine (2t) during the period when the target heat generation 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 in the target gas engine (2t) from the target heat generation amount (QCt) and the target supply amount (MFt); Based on the third association information (AI1), 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) is provided.

[0104] According to the method in 8) above, by using the third association information (AI3) showing 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 generation amount (QC) and the supply amount (MF), which can be obtained from sensors normally installed in the target gas engine (2t) during the operation of the target gas engine (2t). Therefore, according to the method in 8) above, it is possible to estimate the target methane number (MNt) without using a special sensor such as a calorimeter during the operation of the target gas engine (2t).

Explanation of Signs

[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 unit 13 Knocking intensity acquisition unit 14 Methane number estimation unit 21 Cylinder 22 Drive shaft 31 Engine control unit 32 Combustion control unit 33 Combustion diagnosis unit 34 Gas fuel supply amount control unit 35 Ignition timing control unit 41 Fuel injection valve 41 Gas fuel injection device 42 Ignition device 43 Generator 44 Knocking sensor 45 In-cylinder pressure sensor 46 Database section 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 Confluence section 61 Second association information acquisition section 62 Engine load acquisition section 63 Gas supply amount acquisition section 64 Methane number estimation section 71 Third association information acquisition section 72 Heat generation amount acquisition section 73 Supply amount acquisition section 74 Lower heating value 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 amount IT, ITc1, ITc2 Ignition timing ITs Set ignition timing ITt, ITt1 Target ignition timing KI, KIs Knocking intensity KIt, KIt1 Target knocking intensity LHV Lower heating value LHVt Target lower heating value MF Supply amount MFt Target supply amount MN Methane number MNt Target methane number QC Heat generation amount Heat generation amount for QCt S101 First associated information acquisition step S102 Ignition timing acquisition step S103 Knocking intensity acquisition step S104 Methane number estimation step S201 Second associated information acquisition step S202 Engine load acquisition step S203 Gas supply amount acquisition step S204 Methane number estimation step S301 Third associated information acquisition step S302 Heat generation amount acquisition step S303 Supply amount acquisition step S304 Lower heating value calculation step S305 Methane number estimation step

Claims

1. A methane number estimating device for estimating the methane number of gas fuel supplied to a target gas engine which is a gas engine having at least one cylinder, comprising: a second association information acquisition unit that acquires second association information in which an engine load, a gas supply amount of gas fuel supplied, and the methane number of the gas fuel are associated in advance in the gas engine; an engine load acquisition unit that acquires a target engine load which is the engine load in the target gas engine; a gas supply amount acquisition unit that acquires a target gas supply amount which is the gas supply amount during a period in which the target engine load of the target gas engine is acquired; 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 engine load and the target gas supply amount based on the second association information; A methane number estimating device.

2. A methane number estimating device for estimating the methane number of gas fuel supplied to a target gas engine which is a gas engine having at least one cylinder, comprising: a third association information acquisition unit that acquires third association information in which a lower calorific value and the methane number of gas fuel supplied are associated in advance in the gas engine; a heat generation amount acquisition unit that acquires a target heat generation amount which is the heat generation amount per cycle in the target gas engine; a supply amount acquisition unit that acquires a target supply amount which is the supply amount per cycle of gas fuel supplied to the target gas engine during a period in which the target heat generation amount is acquired; a lower calorific value calculation unit that calculates a target lower calorific value which is the lower calorific value in the target gas engine from the target heat generation amount and the target supply amount; 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 lower calorific value based on the third association information; A methane number estimating device.

3. The methane number estimating device according to claim 1 or 2, and an ignition timing control unit configured to control a target ignition timing which is the ignition timing of the target gas engine according to the methane number of the gas fuel estimated by the methane number estimating device; A control device for a gas engine.

4. A methane number estimating method for estimating the methane number of gas fuel supplied to a target gas engine which is a gas engine having at least one cylinder, comprising: A second association information acquisition step of acquiring second association information in which an engine load, a gas supply amount of gas fuel supplied, and a methane number of the gas fuel are associated in advance in a gas engine; An engine load acquisition step of acquiring a target engine load that is the engine load in the target gas engine; A gas supply amount acquisition step of acquiring a target gas supply amount that is the gas supply amount during a period in which the target engine load of the target gas engine is acquired; A methane number estimation step of estimating a methane number of the gas fuel supplied to the cylinder in the target gas engine from the target engine load and the target gas supply amount based on the second association information; A method for estimating methane number.

5. A method for estimating a methane number of gas fuel supplied to a target gas engine that is a gas engine including at least one cylinder, A third association information acquisition step of acquiring third association information in which a lower calorific value and a methane number of gas fuel supplied are associated in advance in a gas engine; A heat generation amount acquisition step of acquiring a target heat generation amount that is a heat generation amount per cycle in the target gas engine; A supply amount acquisition step of acquiring a target supply amount that is a supply amount per cycle of gas fuel supplied to the target gas engine during a period in which the target heat generation amount is acquired; A lower calorific value calculation step of calculating a target lower calorific value that is a lower calorific value in the target gas engine from the target heat generation amount and the target supply amount; A methane number estimation step of estimating a methane number of the gas fuel supplied to the cylinder in the target gas engine from the target lower calorific value based on the third association information; A method for estimating methane number.

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