Method for operating an internal combustion engine and control device for carrying out the method

Abstract

Method for operating an internal combustion engine (1), in particular a marine diesel engine powered by heavy fuel oil, wherein the internal combustion engine (1) comprises an internal combustion engine (2) for combustion of fuel and an exhaust aftertreatment system (3) downstream of the internal combustion engine (2) for cleaning exhaust gas produced during the combustion of the fuel using a reducing agent and / or an absorbing agent, wherein, depending on the cost of the fuel to be burned in the internal combustion engine (2) and depending on the cost of the reducing agent and / or absorbing agent to be used in the exhaust aftertreatment system (3) for exhaust gas aftertreatment, the internal combustion engine (1) is operated at an operating point in which minimal operating costs for fuel and reducing agent and / or absorbing agent are incurred, characterized in that, based on the engine and exhaust aftertreatment parameters, at least one characteristic value,The so-called identifier is generated, from which all emission-relevant settings can be derived and which indicates compliance with the emission limits and / or the use of the respective characteristic map.

Description

[0001] The invention relates to a method for operating an internal combustion engine according to the preamble of claim 1. Furthermore, the invention relates to a control device for carrying out the method.

[0002] Conventional internal combustion engines, such as marine diesel engines, consist of a combustion engine in which a fuel is burned, and an exhaust aftertreatment system downstream of the combustion engine to clean the exhaust gas produced during fuel combustion. Marine diesel engines are preferably operated with heavy fuel oil.

[0003] It is known in practice to subject the exhaust gas in an exhaust aftertreatment system of an internal combustion engine to denitrification and, preferably, desulfurization. According to the prior art, so-called SCR catalysts are used for denitrification of the exhaust gas, which utilize ammonia as a reducing agent. For desulfurization of exhaust gas, absorptive processes are primarily known from the prior art, which use quicklime, hydrated lime, or calcium carbonate as absorbents.

[0004] Such internal combustion engines are known from DE 101 48 661 A1 and JP 2014 - 181 576 A.

[0005] Due to increasing price pressure, there is a need to operate internal combustion engines with minimal operating costs, especially while complying with emission limits. This is currently proving difficult.

[0006] A method for optimized exhaust aftertreatment is already known from US Patent 8 899 018 B2, which includes the consumption-controlled adjustment of fuel and reducing agent to the emissions. However, the described control system is prone to malfunctions.

[0007] Based on this, the present invention aims to create a novel method for operating an internal combustion engine and a control device for carrying out the method.

[0008] This problem is solved by a method for operating an internal combustion engine according to claim 1. According to the invention, the internal combustion engine is automatically operated at an operating point in which minimal operating costs for fuel and reducing agent and / or absorbing agent are incurred, depending on the cost of the fuel to be burned in the combustion engine and depending on the cost of the reducing agent and / or absorbing agent to be used in the exhaust aftertreatment system.

[0009] The present invention proposes a method by which an internal combustion engine can be automatically operated at a specific operating point while providing the requested power output. This operating point minimizes the fuel costs required in the combustion engine and the reducing agents and / or absorbents required in the exhaust aftertreatment system. Depending on the operating costs of the combustion engine and the exhaust aftertreatment system, cost-optimized operation of the internal combustion engine is then possible.

[0010] According to an advantageous further development, raw emissions in the exhaust gas of the combustion engine are automatically adjusted via the amount of fuel supplied to the combustion engine, while providing the required power. This ensures that, as a result of the amount of fuel supplied to the combustion engine and the amount of reducing agent and / or absorbing agent required for exhaust aftertreatment in the exhaust aftertreatment system, minimal operating costs for fuel and reducing agent are incurred, preferably while complying with emission limits. This method for operating the internal combustion engine is particularly advantageous.

[0011] Following a beneficial update, fuel costs and the costs of the reducing agent and / or absorbing agent are automatically updated. Preferably, emission limits are also automatically updated depending on the operating location of the internal combustion engine and / or its operating time. Through the automatic updating of the currently valid operating costs for the internal combustion engine, the currently valid operating costs for the exhaust aftertreatment system, and the currently valid emission limits, the internal combustion engine can always be operated at a cost-optimized operating point.

[0012] Following a beneficial further development, the operating point is automatically determined in such a way that the internal combustion engine is operated within the limits of component load. This prevents the internal combustion engine components from being subjected to excessively high loads.

[0013] Preferred embodiments of the invention are described in the dependent claims and the following description. Exemplary embodiments of the invention are explained in more detail with reference to the drawing, without being limited thereto. The drawing shows: Fig. 1: a block diagram of an internal combustion engine comprising an internal combustion engine and an exhaust aftertreatment system; and Fig. 2: a diagram illustrating the relationship between raw nitrogen oxide emissions in the exhaust gas and the amount of fuel supplied to the combustion engine.

[0014] The invention relates to a method for operating an internal combustion engine and a control device for carrying out the method.

[0015] Fig. Figure 1 shows a highly schematic block diagram of an internal combustion engine comprising an internal combustion engine 2 and an exhaust aftertreatment system 3 downstream of the internal combustion engine 2. Fuel 4 and charge air 5 are supplied to the internal combustion engine 2 for the combustion of the fuel 4, whereby exhaust gas 6 produced during the combustion of the fuel 4 in the internal combustion engine 2 is fed to the exhaust aftertreatment system 3 for exhaust aftertreatment, leaving the exhaust aftertreatment system 3 as cleaned exhaust gas 7.

[0016] In the illustrated embodiment, it is assumed by way of example that the exhaust aftertreatment system 3 is an exhaust aftertreatment system which includes at least one SCR catalyst in which ammonia is required as a reducing agent 8 for exhaust gas purification. In the Fig. In the embodiment shown in Figure 1, this reducing agent 8 is metered into the exhaust gas 6 leaving the internal combustion engine 2 via a metering device 9, so that the reducing agent 8 can be used in the exhaust gas aftertreatment system 3 for exhaust gas purification. In an SCR catalyst, the reducing agent 8, preferably in the form of ammonia, serves to remove nitrogen oxides (NOx) from the exhaust gas 6 using ammonia as the reducing agent. X how NO and NO2 are converted into nitrogen N2 and water vapor H2O.

[0017] An NO oxidation catalyst can be placed upstream of such an SCR catalyst to oxidize NO to NO2 and thus increase the reaction rate in the SCR catalyst.

[0018] For the operation of the in Fig. The internal combustion engine 1 shown therefore incurs operating costs on the combustion engine side, namely the costs of the fuel 4, and operating costs on the exhaust aftertreatment system side, namely the costs of the reducing agent 8, which together significantly define the operating costs of the internal combustion engine 1.

[0019] To operate the internal combustion engine 1 in a cost-effective manner while providing the requested power output, the engine is automatically operated at an operating point where the required power output results in minimal operating costs for fuel 4 and reducing agent 8. This is determined based on the cost of the fuel 4 to be burned in the combustion engine 2 and the cost of the reducing agent 8 used in the exhaust aftertreatment system 3 for exhaust gas purification. This is preferably achieved by controlling the quantity of fuel 4 supplied to the combustion engine 2, which, for example,In common-rail injection systems, the raw emissions in the exhaust gas 6 of the combustion engine 2 can be influenced for a large part of the engine's power range by shifting the injection timing. This allows for automatic adjustment of the raw emissions in the exhaust gas 6 of the combustion engine 2 in such a way that minimal operating costs for fuel 4 and reducing agent 8 are incurred as a result of the amount of fuel supplied to the combustion engine 2 and the amount of reducing agent 8 required for exhaust aftertreatment in the exhaust aftertreatment system 3. For example, nitrogen oxide emissions increase by advancing the injection timing and / or increasing the injection pressure. Other engine parameters that influence raw NOx emissions are the fuel / air ratio and the number of fuel injections. The influence of the injection timing K on raw NOx emissions is described in [reference missing]. Fig. Figure 2 shows that early injection timing (low K-values) leads to an increase in raw NOx emissions. With increasing nitrogen oxide emissions, more reducing agent 8 is required to clean the exhaust gas 6 in the exhaust aftertreatment system 3 while complying with emission limits for nitrogen oxide emissions.Depending on the amount of fuel supplied to the combustion engine 2 and the associated fuel costs, and depending on the amount of reducing agent supplied to the exhaust aftertreatment system 3 and the cost of the reducing agent required to clean the exhaust gas 6 leaving the combustion engine 2, an operating point for the combustion engine 1 is automatically determined and the combustion engine 1 is automatically operated at this operating point, so that the combustion engine 1 can be operated optimally with regard to the operating costs of fuel and reducing agent, while complying with the relevant emission limits and providing the required power.

[0020] According to the present invention, a control device 10 is provided for carrying out the method according to the invention, comprising means for carrying out the method according to the invention. These means are hardware-related means and software-related means. The hardware-related means are, in particular, data interfaces for exchanging data with the assemblies involved in carrying out the method according to the invention. Furthermore, the hardware-related means include a data storage device for storing data and a processor for processing data. The software-related means are program modules that are implemented in the control device 10 for carrying out the method according to the invention.

[0021] According to the invention, it is therefore provided that the control device 10 automatically determines an operating point for the internal combustion engine 1 depending on the operating costs for fuel 4 to be burned in the combustion engine 2 and depending on the operating costs for reducing agent 8 required for exhaust aftertreatment in the exhaust aftertreatment system 3 and automatically operates the internal combustion engine 1 at this operating point, so that minimal operating costs for fuel 4 and reducing agent 8 result while providing the requested power.

[0022] Following advantageous further training, it may be possible to automatically update the emission limits that must be observed during the operation of the internal combustion engine 1. For example, it may be possible to automatically provide the control unit 10 with the currently applicable emission limits, depending on the current operating location and / or the current operating time of the internal combustion engine 1, in order to then determine the cost-optimized operating point for the internal combustion engine 1 based on these currently applicable emission limits, so that ultimately the total operating costs for fuel 4 and reducing agent 8 are minimized.

[0023] It may be possible to automatically monitor compliance with the emission limits using at least one sensor 11, which is located in Fig. 1 is assigned to the exhaust aftertreatment system 3, and the emissions of the cleaned exhaust gas 7 are checked with regard to compliance with emission limits. The signal from sensor 11 then serves as an input for the control unit 10, so that it can determine the cost-optimal operating point for the internal combustion engine 1 while complying with the applicable emission limits.

[0024] According to a further advantageous embodiment of the invention, the costs of the fuel 4 and the costs of the reducing agent 8 are automatically updated. This can be done with each refueling of the internal combustion engine 1, i.e., with each refueling of the engine with fuel 4 and / or reducing agent 8. If the ratio of the operating costs of fuel and reducing agent changes, the optimal operating point, at which the internal combustion engine 1 is preferably operated in compliance with the current emission limits, also changes.

[0025] According to a further advantageous embodiment of the invention, the operating point at which the internal combustion engine 1 is operated can be determined in such a way that it is operated within component load limits. Thus, neither in the area of ​​the internal combustion engine 2 nor in the area of ​​the exhaust aftertreatment system 3 may load limits for corresponding assemblies be exceeded in order to avoid damage to these assemblies. According to this embodiment of the invention, the cost-optimized operating point for the internal combustion engine 1 is therefore automatically determined depending on the emission limits to be observed and the component load limits to be observed.

[0026] Compliance with component load limits can also be monitored using a suitable sensor, for example, in the area of ​​the combustion engine 2 using a temperature sensor. Based on the measurement signals from this sensor, it can be monitored to ensure that permissible component temperatures in the combustion engine 2 are not exceeded. Alternatively or additionally, compliance with component load limits can be monitored using characteristic maps.

[0027] It is therefore in accordance with the present invention that, depending on the operating costs of the combustion engine and the exhaust aftertreatment system, in particular fuel costs and reducing agent costs, an operating point for an internal combustion engine 1 is automatically determined and the internal combustion engine 1 is automatically operated at this operating point, namely at an operating point in which, while providing the required engine power and complying with emission limits and / or component load limits, the total operating costs are minimal. Operating costs and / or emission limits can be updated automatically, in particular via a corresponding interface of the control unit 10.When a ship's internal combustion engine is operated, emission limits can, for example, be automatically and continuously updated based on the current position in order to continuously redetermine the operating point that optimizes operating costs.

[0028] Since different emission classes are relevant in the maritime sector, such as IMO Tier II or Tier III, the relevant emission limit is also taken into account when optimizing the operating point, either through manual input or based on the current position, i.e., the location, particularly via satellite-based systems. With satellite-based systems (e.g., GPS), it is also considered that a lead time may be necessary to reliably reach the emission limits. This necessary lead time is factored in, and the switchover occurs accordingly earlier.

[0029] Unlike previous state-of-the-art technology, the operating point is selected using a map-based system rather than a control system that is prone to errors. Different maps are stored for different price levels and different fuels. By entering the prices for fuel and reducing agents in combination with the applicable emission limit, the most economical map is selected.

[0030] The most cost-effective permissible configuration is therefore selected by determining the relevant emission limit and automatically choosing the most cost-effective operating point based on the operating costs of the fuel and the reducing agent. This also takes into account that a lead time may be necessary to reliably achieve the emission limits. This necessary lead time is factored in, and the switchover occurs accordingly earlier.

[0031] By using characteristic maps, it is possible to make the actual, current emission behavior of the system visible and readable externally. For this purpose, a key figure, the so-called identifier, is generated based on the engine and exhaust aftertreatment parameters. This identifier is generated, for example, from the checksum of the settings or based on measured values. It reveals all emission-relevant settings and indicates compliance with emission limits and / or the use of the respective characteristic map. If the engine or exhaust aftertreatment settings are changed to ensure the most cost-effective operation, the identifier also changes. Since each characteristic map for the engine and exhaust aftertreatment can be assigned exactly one identifier, compliance with the correct emission class can be easily monitored externally in a characteristic map-based system.

[0032] With reference to Fig.In Section 1, the invention was described by way of example for the case in which the exhaust aftertreatment system 3 comprises an SCR catalyst in which ammonia is required as a reducing agent 8 for the denitrification of the exhaust gas 6 of the internal combustion engine 2. It should be noted at this point that the invention is not limited to this preferred application. Rather, the invention can also be used if the operating costs of the exhaust aftertreatment system 3 include costs for absorbents, which are required, for example, for the desulfurization of the exhaust gas 6 in the exhaust aftertreatment system 3.

[0033] The invention makes it possible to automatically operate an internal combustion engine at an optimal operating point in terms of operating costs, always depending on the corresponding operating costs on the combustion engine side and the exhaust aftertreatment system side, while complying with emission limits and / or component load limits.

[0034] In particular, this makes it possible for the internal combustion engine to be operated with different fuels and, when operating with different fuels, such as heavy oil, refined diesel fuel or gas, to use different maps specified for each fuel used.

[0035] Another embodiment provides that, in the event of a failure of the exhaust aftertreatment system, the raw emissions of the engine and / or the type of fuel are automatically selected to ensure compliance with the applicable limit values. Reference symbol list 1 internal combustion engine 2 Internal combustion engine 3 Exhaust aftertreatment system 4 Fuel 5 Charge air 6 Exhaust gas 7 Exhaust gas 8 Reducing agents 9 Dosing device 10 Control unit 11 Sensor

Claims

[1] Method for operating an internal combustion engine (1), in particular a marine diesel engine powered by heavy fuel oil, wherein the internal combustion engine (1) comprises an internal combustion engine (2) for burning fuel and an exhaust aftertreatment system (3) downstream of the internal combustion engine (2) for cleaning exhaust gas produced during the combustion of the fuel using a reducing agent and / or an absorbing agent, wherein, depending on the cost of the fuel to be burned in the internal combustion engine (2) and depending on the cost of the reducing agent and / or absorbing agent to be used in the exhaust aftertreatment system (3) for exhaust gas aftertreatment, the internal combustion engine (1) is operated at an operating point in which minimal operating costs of fuel and reducing agent and / or absorbing agent are incurred, characterized by, that based on the engine and exhaust aftertreatment parameters at least one key figure, the so-called identifier, is formed, from which all emission-relevant settings can be derived and which indicates compliance with the emission limits and / or the use of the respective map. [2] Method according to claim 1, characterized by , that by changing at least one of the following engine parameters: - Fuel / air ratio - Fuel injection pressure - Fuel injection timing - The number of injections is automatically adjusted to reduce the raw emissions in the exhaust gas of the combustion engine (2) in such a way that, as a result of the amount of reducing agent and / or absorbing agent required for exhaust aftertreatment in the exhaust aftertreatment system (3), minimal operating costs for fuel and reducing agent and / or absorbing agent are incurred. [3] Method according to claims 1 and 2, characterized by, that to change the raw emissions of the internal combustion engine and the conversion behavior of the exhaust aftertreatment device, and thus to determine the required amounts of reducing agents and / or absorbing agents, reference is made to characteristic maps. [4] Method according to claim 1 or 2, characterized by , that the costs of the fuel and the costs of the reducing agent and / or absorbenant are updated. [5] Method according to any one of claims 1 to 3, characterized by , that the operating point is automatically determined in such a way that the internal combustion engine (1) is operated in compliance with emission limits. [6] Method according to claim 4, characterized by , that the emission limits are updated depending on the operating location and / or the operating time of the internal combustion engine (1). [7] Method according to claim 4 or 5, characterized by, that compliance with the emission limits is automatically monitored with the help of at least one sensor (11) or on the basis of the current position, i.e. the location, in particular via satellite-based systems (GPS) and, in the event of non-compliance with the emission limits, the operating point is automatically adjusted taking into account minimizing operating costs. [8] Method according to any one of claims 1 to 6, characterized by , that the operating point is automatically determined in such a way that the internal combustion engine (1) is operated in compliance with component load limits. [9] Method according to claim 7, characterized by , that compliance with the component load limits is automatically monitored with the help of at least one sensor and, if the component load limits are not met, the operating point is automatically adjusted taking into account minimizing operating costs. [10] Method according to claim 1, characterized by, that in the event of a failure of the exhaust aftertreatment system, the raw emissions of the engine and / or the type of fuel are automatically selected to ensure compliance with the applicable limit values. [11] Method according to any of the preceding claims, characterized by , that the engine can be operated with different fuels and that different maps are used when operating with different fuels. [12] Control device for operating an internal combustion engine, characterized by that it has the means to carry out the method according to any one of claims 1 to 8.

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