JP2021105399A - Method of operating large diesel engine, use of the method, and large diesel engine - Google Patents

Abstract

To provide a method of operating a large diesel engine, use of this method, and the large diesel engine.SOLUTION: In a method of operating a large diesel engine, the large diesel engine can be operated in a gas mode or a transient mode. In the gas mode, a gas is introduced into a cylinder as a fuel, and in the transient mode, a liquid fuel is introduced into the cylinder in addition to the gas. The method includes: a step 13 of changing the large diesel engine from the gas mode to the transient mode; a step of specifying a desired value of an engine rotating speed or torque; a step 14 of determining a maximum amount of the gas to be utilized as the fuel in each work cycle of the large diesel engine; and a step 14 of determining an additional amount of the liquid fuel to be introduced into the cylinder in addition to the gas, to compensate a difference between the desired value of the rotating speed or torque and a value achieved by using the maximum amount of gas.SELECTED DRAWING: Figure 3

Description

The present invention relates to the use of large diesel engines, large diesel engines, and preambled methods of independent claims in their respective categories.

A large diesel engine, which can be configured as a two-stroke or four-stroke machine, eg, a two-stroke large diesel engine that is scavenged in the vertical direction, is often used as a drive assembly for ships, or, for example, a large generator. Also used in stationary operation mode to drive and generate electrical energy. In this regard, the engine is generally operated in continuous operation mode for a considerable period of time, which presents high requirements for operational safety and operability. Therefore, a particularly long interval between maintenance, low wear, and the economic availability of operating fuel are important criteria for the driver.

In recent years, another essential point and an increasingly important point is the quality of the exhaust gas, especially the concentration of nitrogen oxides in the exhaust gas. In this regard, legal provisions and thresholds for the corresponding exhaust gas values are becoming increasingly stringent. This is because maintaining exhaust gas thresholds becomes increasingly difficult, technically more demanding, and therefore more expensive, or ultimately even impossible to maintain in common sense. The inevitable consequence is that the combustion of classic heavy fuel oils with a high degree of pollutants, and the combustion of diesel oil or any other fuel, becomes more and more problematic, especially when considering two-stroke large diesel engines. Leads to.

As such, in practice, requirements for so-called "dual fuel engines" have existed for a long period of time, which means that the engine can be operated using two different types of fuel. In gas mode, gas, such as natural gas such as LNG (liquefied natural gas), or in the form of liquefied petroleum gas or in a different form of gas suitable for driving a combustion engine, is burned, while in liquid mode, gasoline. , Diesel, suitable liquid fuels such as heavy fuel oil, or different suitable liquid fuels are burned in the same engine. The engine may be both a two-stroke engine and a four-stroke engine in this regard, and these engines may be small, medium and large engines, especially longitudinally scavenged. It may be a two-stroke large diesel engine.

Also, by using the term "large diesel engine", there is a form different from the diesel operation mode characterized by self-ignition of fuel, and a gasoline engine operation mode characterized by external ignition of fuel, or two of these. A large engine that can be operated in a mixed operation mode is intended. The term large diesel engine further includes, among other things, so-called dual fuel engines, and such large engines where self-ignition of fuel is used for external ignition of different fuels.

In liquid mode, the fuel is usually introduced directly into the combustion space of the cylinder, where it is burned according to the principle of self-ignition. In gas mode, it is therefore known to mix gaseous gas with scavenging air according to the Otto principle operating mode to produce an ignitable mixture in the combustion space of the cylinder. Considering this low pressure scheme, the ignition of the mixture occurs in the cylinder in that a small amount of liquid fuel is injected into the combustion space or pre-combustion chamber of the cylinder at the appropriate time, which in turn results in the ignition of the air-gas mixture. The dual fuel engine can switch to liquid mode while operating in gas mode and vice versa.

However, a pure gas engine, which means an engine that can be operated using only gas and cannot be operated with diesel, heavy fuel oil or different fuels, also has high requirements, especially for exhaust fumes. Is in demand when required, and its high requirements can only be maintained by burning gas, using acceptable technical requirements and in an economically feasible way. Such a pure gas engine is provided, for example, in International Publication No. 2010147071 (A1) Pamphlet. Other state-of-the-art techniques are provided, for example, in German Patent Application Publication No. 102010005814 (A1).

Regardless of whether the engine is a dual fuel engine or a pure gas engine, the corresponding round trip is required to operate such an engine reliably, with less contaminants and safely. The process of introducing fuel gas into the combustion space of the cylinder of a piston combustion engine is extremely important.

In gas mode, it is very important to set the proper ratio of scavenging air to gas, the so-called air-fuel ratio. Scavenging air or charging air is usually available by a turbocharger in a large diesel engine, which is determined by the load of the engine and thus the output and / or torque and / or rotation of the engine. It produces scavenging air pressure, or loading air pressure, which is determined by speed. For a given scavenging air pressure, the amount of air in the cylinder can be calculated, then the drive torque required for each produced by the engine can be determined, and / or this operating condition. It is possible to determine the appropriate amount of gaseous fuel for the desired amount of rotational speed, torque, and / or rotational speed that results in the ideal combustion process for.

Appropriate setting of the smallest possible air-gas ratio is for the operation of the engine, especially when operating in gas mode according to the Otto principle, from a pollution point of view and because it can be carried out effectively and economically. Is very important. If the gas ratio is too high, the air-gas mixture will be too rich. Combustion of the mixture occurs excessively fast or very early, resulting in engine knocking. The combustion process no longer adequately matches the movement of the piston in the cylinder, and above all, this also results in combustion that acts partially on the movement of the piston.

Also, if the proper setting of the air-gas ratio no longer presents any major problems in modern large diesel engines under normal operating conditions, the problems are very sudden, frequent and powerful. It often occurs under operating conditions where the load changes.

An example to mention in this regard is a vessel driven by a large diesel engine, sailing in rough seas. This inevitably means that the ship propellers, driven directly by the engine, will appear more or less periodically, partially or even completely above sea level due to the high waves, and then again completely submerged in the sea. Can bring about positive results. This, of course, has a very large and sudden change in drive torque transmitted into the sea as an inevitable result of the engine load and / or the engine. The turbocharger system for utilizing scavenging air reacts to changes in the engine load in a phase-shifted manner, so in such an operating mode the scavenging air pressure is too low and the air-gas mixture in the cylinder. Is too rich, which can be very prone to fast combustion or knocking combustion, which is of course a drawback. Such rapid and abrupt load changes in gas mode are extremely difficult to adjust or even impractical at all, thus for example downward or continuous changes in engine performance and / or engine speed. Conformity is required, otherwise a change from gas mode to liquid mode is required. However, considering, for example, a large diesel engine operating in liquid mode using heavy fuel oil, the exhaust gas value can no longer be maintained in liquid mode, so near the coast due to existing emissions requirements. Is no longer allowed to operate in liquid mode.

A different example in which engine load can change very suddenly, frequently, or strongly is the practice of ship exercises.

International Publication No. 2010147071 (A1) Pamphlet German Patent Application Publication No. 102010005814 (A1)

Therefore, an object of the present invention, starting with the latest technology, is a method of operating a large diesel engine, for example, sudden, frequent, of loads such as those occurring on a ship in a heavy swell or on a ship performing exercises. Or to propose a method that can still operate a large diesel engine in an equally reliable, effective and environmentally friendly manner against strong changes. Furthermore, an object of the present invention is to propose a corresponding large diesel engine.

The subject matter of the present invention that satisfies this object is characterized by the characteristics of the independent claims of each category.

Therefore, according to the present invention, it is a method of operating a large diesel engine capable of operating in at least one gas mode in which gas is introduced into the cylinder as fuel, while operating in the gas mode. A state of strong change in load is detected, then a large diesel engine is operated in transient mode, and transient mode is
-Steps to identify the desired value for engine speed or the desired value for engine torque, and
− Steps to determine the upper threshold for the amount of gas that can be used as fuel for each work cycle of a large diesel engine, and
-A method that includes a step in which the additional amount of liquid fuel introduced into the combustion space in addition to the gas is determined and the additional amount is measured so that the desired value for rotational speed is achieved. Proposed.

Because the amount of gas supplied is limited to the upper threshold (the upper threshold is measured so that the combustion of the air-gas mixture in the cylinder does not occur in the range of combustion that is too fast or in the range of knocking combustion). Gas also for sudden, frequent or periodic changes in load or load shifts, without the risk of inefficient, pollutant-rich and unfriendly operating mode results. It is possible to use the mode. Second, if the output that is insufficient to achieve the required desired rotational speed due to the limitation or reduction of the gas supply is in transient operation mode, then a certain amount of liquid fuel is introduced into the cylinder in addition to the gas. Produced by its combustion, which provides insufficient energy and / or power.

Thus, the method according to the invention provides a similar response to load in a large diesel engine operating in at least one gas mode, as is possible in a large diesel engine operating only in liquid mode. It is possible. This prevents the air-gas mixture in the cylinder from becoming too rich, and the additional combustion of liquid fuel, which generally occurs according to the diesel principle, does not react so sensitively to changes in scavenging air pressure. By making it possible.

Preferably, the large diesel engine is configured as a dual fuel engine for the combustion of gas and for the combustion of liquid fuels, especially diesel or heavy fuel oil. As described above, according to the method according to the present invention, the dual fuel engine can still be effectively operated in the gas operation mode even in consideration of sudden and frequent load changes. For important cases of large diesel engine applications as ship drive assemblies, this means that gas mode can still be used effectively, even considering the same severe swells. According to the method according to the invention, the smoothness of the engine is enhanced and speed fluctuations are significantly reduced.

It is advantageous that the actual pressure of each of the available scavenging air is drawn to determine the upper threshold for the amount of gas. According to this method, the portion based on the combustion of gas can be optimized.

According to the first embodiment, the transient mode is started manually. Thus, for example, a driver on a ship can activate the transient mode of the engine when a severe swell appears.

Alternatively or additionally, the transient mode is the actual pressure of the scavenging air, the cylinder pressure, the calculated air-gas ratio, the knocking detector signal, the ratio of the rotational speed to the engine load, the rotational speed to the engine load. It can be initiated according to at least one parameter of change relative to ratio, engine torque, change in torque, amount of fuel required for injection, and change in amount of fuel required for injection. Is preferable. It is also possible to automatically activate the transient mode by determining at least one of these parameters continuously or adjusted.

There are several preferred variants for introducing additional amounts of liquid fuel into the combustion space in transient mode.

Additional amounts of liquid fuel can be introduced into the combustion space by the injection device used in the liquid mode of large diesel engines.

An additional amount of liquid fuel can be introduced into the combustion space by a pilot injection device used in gas mode to ignite the gas.

An additional amount of liquid fuel can be introduced into the combustion space by a separate injection device provided for the transient operating mode.

Further, considering the supply of gas to the combustion space, there are a plurality of preferred modifications.

The supply of gas into the cylinder can be generated via the cylinder liner. To that end, commonly known gas supply systems are known to be provided on the walls of the cylinder and to introduce gas into the interior space of the cylinder via a cylinder liner. Such gas supply systems are preferably arranged such that they introduce gas into the cylinder at a distance from the top or bottom center of the piston in the cylinder. Such an interval ranges from 40% to 60%, preferably 50%, of the interval between the upper death center position and the lower death center position.

The gas supply into the cylinder can also be generated by the cylinder head. Gas supply systems are also known for this purpose.

It is also possible to supply gas to the scavenging air before it is introduced into the cylinder, or to supply gas when the scavenging air is introduced into the cylinder. Also, the last mentioned variant can be realized, among other things, such that one or more gas inlet nozzles are provided to one or more webs that separate adjacent scavenging air openings or scavenging air slits from each other. ..

According to the present invention, there are further proposed large diesel engines that can be operated in at least one gas mode and operated according to the method according to the invention. The advantages thus obtained correspond to the same description provided above and made with reference to the methods according to the invention.

Preferably, the large diesel engine is configured as a dual fuel engine for the combustion of gas and for the combustion of liquid fuels, especially diesel or heavy fuel oil.

In a preferred embodiment, engine control is provided that has a control device for initiating and performing a transient operation mode.

Further, the present invention proposes the use of the method according to the invention for retrofitting large diesel engines, especially dual fuel engines. The method according to the invention is also suitable, among other things, for modification and / or retrofitting of existing large diesel engines, as it can be implemented in many application cases without greater additional requirements from an equipment perspective. In this method, driving them in a more effective, safe and economically feasible manner, especially considering the frequent and sudden changes in load, for example in the case of severe swells. can do.

Other advantageous means and designs of the present invention are obtained by the dependent claims.

Hereinafter, the present invention will be described in detail by way of examples and with reference to the drawings from both the viewpoint of the apparatus and the viewpoint of process engineering.

It is a schematic diagram for visualizing the dependence of torque on the air-gas ratio in the example of the large diesel engine of one embodiment of the present invention. It is a schematic diagram which shows the Example of the method by this invention. It is an exemplary schematic which shows the progress of torque with time.

Considering the following description of the present invention with reference to one embodiment, the practice of a large diesel engine configured as a dual fuel engine meaning an engine capable of operating with two different types of fuels. Illustrative features for particularly important cases of application are referenced. This embodiment of a large diesel engine in particular can be operated in a liquid mode in which only liquid fuel is injected into the combustion space of the cylinder. Usually, liquid fuels such as heavy fuel oil or diesel oil are injected directly into the combustion space at the appropriate time, where they ignite according to the self-igniting diesel principle. However, large diesel engines can also be operated in a gas operating mode in which the gas acts as fuel, for example natural gas is introduced into the combustion space in the form of an air-gas mixture and ignited. Large diesel engines in particular operate in gas operating mode according to the low pressure scheme, which means that the gas is introduced into the cylinder in a gaseous state. In this regard, mixing with air can occur within the cylinder itself, or can occur at the front stage of the cylinder as well. The air-gas mixture is externally ignited according to the Otto principle. This external ignition usually occurs by introducing a small amount of liquid fuel into the combustion space at the appropriate time and then self-igniting, thereby externally igniting the air-gas mixture.

The large diesel engine can be configured as both a 4-stroke engine and a 2-stroke engine. Considering the embodiment described in this example, the large diesel engine is configured as a vertically scavenged two-stroke large diesel engine operating in liquid mode with a common rail system.

For example, an injection system for a liquid mode, a gas supply system for a gas mode, a gas exchange system, an exhaust gas system or turbo for preparing scavenging air (scavenging) and / or supply air (supply). Large diesel engine assemblies and individual components, such as charger systems and control and adjustment systems for large diesel engines, are well known to those of skill in the art and are therefore designed as two-stroke engines and 4 Considering both the design as a stroke engine, no further explanation is needed here.

Considering the embodiment described in this example of a two-stroke large diesel engine that is longitudinally scavenged, scavenging air slits are typically provided in the lower region of each cylinder and / or cylinder liner and scavenging air slits. When opened, the scavenging air slits are periodically opened and closed by the movement of the piston in the cylinder so that the scavenging air provided by the turbocharger can flow through these scavenging slits into the cylinder at charge pressure. NS. A centrally located outlet valve is typically provided in the cylinder head and / or cylinder cover, through which the combustion gas after the combustion process is once again exhausted from the cylinder to the exhaust system. You can go out to. One or more fuel injection nozzles are provided, for example, placed in a cylinder head near the outlet valve to introduce liquid fuel. The gas supply system is provided to supply gas in gas mode and has at least one gas inlet valve with a gas inlet nozzle. The gas inlet nozzle is usually provided to the wall of the cylinder at a height approximately midway between, for example, the center of death and the center of bottom of the piston.

Further, in the following, as an example, an example of an application in which a large diesel engine is a drive assembly of a ship will be referred to.

Due to legal provisions regarding exhaust gas values, large diesel engines are often operated in gas operating mode in the vicinity of the coast today. This is because otherwise, it is impossible to maintain the exhaust gas emissions, defined the threshold with respect to, inter alia nitrogen oxides NO _x and release of sulfur dioxide (emission) longer.

In the gas operating mode, efficiency and combustion of the air-gas mixture with as little pollutant as possible are extremely sensitive to the ratio of the amount of air to the amount of gas. This ratio is usually expressed by a λ value, which is used in relation to the ratio of the mass of air available for combustion to the mass of gas used as fuel.

The ideal air-gas ratio depends on the drive torque produced by the engine and, in this method, on the desired speed of the vessel. Large diesel engines are usually directly connected to the propellers of the ship, so the speed corresponds to the rotational speed of the engine.

A very schematic representation of FIG. 1 shows an exemplary relationship between an air-gas ratio of 1 and a torque of 2 generated by an engine driving a ship. This illustration is true for a particular torque that corresponds to the ship's specified speed (ie, the particular rotational speed of the engine) when the vessel is moving in essentially calm water. In particular, the torque 2 shown in FIG. 1 is essentially mean over one work cycle (one cycle of piston movement for a two-stroke machine and two cycles of piston movement for a four-stroke machine). BMEP torque (net mean effective pressure torque), which is the torque obtained.

In the illustration of FIG. 1, two boundary curves, that is, a first knocking curve 3 and a non-ignition curve 4 are shown. Considering the operating conditions that appear above the knocking curve 3 according to the illustration, the air-gas ratio is rich, which means that there is too little air in the mixture. When the gas becomes too rich, the mixture has a different problem: combustion occurs too quickly (fast combustion), or the engine starts knocking, or typically the gas content in the cylinder. Self-ignition due to too much can cause problems with the mixture starting premature combustion (with respect to the work cycle, also known as pre-ignition). Considering the operating conditions that occur above the non-ignition curve 4 according to the illustration, the air-gas ratio is too poor in gas, which is insufficient gas for ideal combustion in the combustion space. It means that.

Therefore, efforts are always made to operate a large diesel engine at the ideal point 5 with respect to the air-gas ratio. In practice, it is not possible to avoid or adjust the natural deviation of torque and / or air-gas ratio 1 to maintain the same constant rotational speed and / or constant speed of the vessel, and therefore. In FIG. 1, there is a permissible range 6 limited by two straight lines 7 and 8, and within this permissible range, a deviation of the air-gas ratio 1 from the ideal point 5 is allowed. The ideal operation in gas mode is shown in FIG. 1 by the operating point referenced in A.

When a ship moves away from calm water (see Figure 1) and encounters severe swells, very sudden and powerful changes in load can occur in the engine, which is caused by the engine to enter the water through the ship's propellers. It means that the torque applied can change rapidly and significantly (change in load). Thus, for example, in rough seas, it is possible that ship propellers will appear partially or completely above sea level over a short period of time, which will significantly reduce the actual load on the engine. If the ship's propellers are subsequently completely submerged in the sea again, the load will be significantly higher and therefore the torque will be higher. In FIG. 1, this actually moves from, for example, point A to the point referenced by B, which is above the knocking curve 3 and thus is in the range of "fast combustion" and / or knocking. Means. Due to the phase shift response of the turbocharger system, it is no longer possible to utilize scavenging air at the required charge pressure, making the air-gas mixture too rich.

In rough seas, these powerful fluctuations in engine load occur frequently, one after the other, almost periodically, making it no longer possible for large diesel engines in gas mode to be effective, economical, and low-emission operating modes. Is.

Improvement actions are provided by the methods according to the invention. FIG. 2, which is shown very schematically, shows an example of the method according to the present invention. At the starting point of step 10, the large diesel engine is operated in gas mode. If the vessel is encountering rough seas, this condition shall be detected by the operator's observation 11 and / or by evaluating the operating parameters detected by the engine controller or different controllers in step 12. Can be done. If it is determined that the strong change in the resulting load is too large, then in step 13 it is determined to switch the large diesel engine to transient mode. In this transient mode, the desired value of engine speed or torque produced by the engine is first determined. This may be, for example, a value corresponding to the movement of the ship in calm water. The controller then determines in step 14 an upper threshold for the amount of gas that can be used as fuel for each work cycle of the large diesel engine. In this regard, this upper threshold is determined so that there is sufficient scavenging air available in the cylinder 21 to burn the maximum amount of gas determined by this upper threshold, thereby "fast". The range of "combustion" and / or knocking combustion is avoided and therefore the air-gas ratio does not become too rich. The upper threshold for the maximum permissible gas amount to avoid exceeding the knocking threshold 3 (FIG. 1) depends on the amount of air present in the cylinder. Given the known cylinder volume, this amount of air can be determined using the charge pressure of available scavenging air. In this regard, of course, the deviation of the charge pressure is taken into account, which means that the minimum charge pressure that can be used in all cases is advantageously assumed. It is also, of course, possible to derive experimental values or different known operating parameters of the large diesel engine in determining the appropriate upper boundary for the amount of gas.

Particularly preferably, the currently available charge pressure of the scavenging air is drawn to determine the upper threshold of the amount of gas. This charge pressure is usually detected by measurements in a large diesel engine and can be utilized in and / or transmitted to the controller in this method. In particular, in this regard, the determination of the upper threshold for the amount of gas can be determined using the difference between the current value of currently available scavenging air and the required charge pressure of the scavenging air. The charge pressure required for the actual operating parameters is stored, for example, in a lookup table or lookup matrix.

In this case, the controller has an upper threshold determined by the charge pressure for the amount of gas that can be supplied to the cylinder as combustion gas, and the amount of gas is limited to this upper threshold. Thus, the rotational speed or torque produced by the engine can be maintained at the desired value, and in step 14, the controller further defines an additional amount of liquid fuel, which is the desired value of rotational speed or torque. , Measured to compensate for the difference from the value achieved using the maximum amount of gas.

This means that the controller determines a value for torque or rotational speed that can be achieved using the maximum amount of gas determined by the upper threshold. Next, the difference between the desired value and this value is determined. Subsequently, the amount of liquid fuel required to compensate for this difference is determined.

Next, in step 15, a determined amount of gas is introduced into the cylinder and burned in the same manner as in gas mode. At the same time, this means that in the same work cycle, an already determined amount of liquid fuel is introduced into the cylinder in step 16 where it ignites itself. According to this method, the rotation speed or torque of a desired value can be generated by the common combustion of the gas and the liquid fuel additionally introduced. In this regard, liquid fuel self-ignition can be used for external ignition of air-gas mixtures.

In step 17, by observation of the operator and / or determination of the operating parameters, it is checked continuously or at regular intervals whether the conditions for invoking the transient mode are still met. In the case of yes, the transient mode is maintained as shown by arrow 18 in FIG. 2, preferably the values for the upper threshold of the amount of gas and the values for the additional amount of liquid fuel are checked and / Or it will be updated.

If the conditions for the transient mode are no longer met in the check in step 17, the normal gas mode can be changed again in step 19.

The control device for starting and implementing the transient mode is preferably integrated into engine control.

According to this method, by combining the combustion of gas and the combustion of liquid fuel, the rotation without gas combustion occurs in the "fast combustion" range and / or the knocking range and / or the "premature ignition" range. It is guaranteed that the desired value for engine speed, which means speed, or the desired value for torque can be maintained in transient mode. The upper threshold for the amount of gas ensures that the air-gas mixture in the combustion space is not too rich.

Thus, for example, by this method, a dual fuel large diesel engine operating according to the Otto principle in gas operating mode is of the load of a large diesel engine operating exclusively according to the diesel principle, which is operated exclusively using liquid fuel. A response to change can be achieved that is at least about the same as the response to change. On the one hand, with respect to the method according to the invention and / or with respect to the large diesel engine according to the invention, the air-gas mixture is guaranteed not to be too rich, and on the other hand, the combustion portion associated with the liquid fuel is scavenged. Remarkably insensitive to too low a charge pressure of air. According to this method, the operational stability of a large diesel engine can be improved and the speed fluctuation can be reduced, especially in rough seas, during the same gas operation mode.

The schematic diagram of FIG. 3 emphasizes the cooperation between the combustion of gas and the combustion of liquid fuel in the transient mode, also according to an example. The torque T of the large diesel engine is applied depending on the time t as it may occur in consideration of the rough sea. The high wave motion encountered by the ship causes (almost) periodic and timely changes in torque T. Curve G shows the portion of torque produced by the combustion of the gas, the maximum amount of gas being limited to sufficient scavenging air available, thereby enriching the air-gas mixture. It is designed not to be too much. The two curves, with the reference symbol F, limiting the area indicated by hatching indicate the amount added to the torque T produced by adding the combustion of the liquid fuel.

During the transient mode, there are different possibilities for introducing additional amounts of liquid fuel into the combustion space of the cylinder. When a large diesel engine is configured as a dual fuel engine, liquid fuel can be injected using the same injection device that is also used to inject fuel in liquid mode.

Another possibility for introducing liquid fuel in transient mode is that the pilot injection device used in gas mode to ignite the air-gas mixture allows the liquid fuel to be introduced into the combustion space. ..

Of course, it is also possible to provide a separate injection device for introducing the liquid fuel during the transient mode. This is especially preferred when the large diesel engine is not configured for liquid mode and does not have a corresponding injection device.

Considering the introduction of gas into the combustion space of the cylinder, there are some preferred modifications between both transient and gas modes as well. As already mentioned above, a gas supply system having at least one gas inlet nozzle can be provided, the at least one gas inlet nozzle capable of introducing gas into the cylinder, where scavenging air. It is placed in a cylinder liner so that it can be mixed with and made into an ignitable air-gas mixture.

However, it is also possible to provide one or more gas inlet nozzles in the cylinder head and / or cylinder cover so that the gas supply into the cylinder comes from the cylinder head and then the gas mixes with the scavenging air. It is possible.

There are other possibilities to supply gas to the scavenging air before it is introduced into the cylinder. In this case, the gas is already mixed with the air-gas mixture outside the cylinder internal space using scavenging air, which is then introduced into the cylinder by, for example, a scavenging air slit or scavenging air opening. Will be done. Thereby, a gas supply to the scavenging air can be generated at one point between the outlet of the turbocharger system and the inlet opening to the internal space of the cylinder, for example, the scavenging air slit.

In particular, it is also possible to supply gas to the scavenging air as it is introduced into the cylinder. To that end, in this case, for example, one or more gas inlet nozzles on one or more webs that separate adjacent scavenging air slits so that the scavenging air mixes with the gas while passing through the scavenging air slits. Can be provided respectively.

The operating parameters determined in step 12 (FIG. 2) or analyzed in step 13 to determine whether to change to transient mode are preferably parameters already present in engine control. It means that it is a value that can be detected or derived from such parameters for the operation of a large diesel engine or while operating a large diesel engine.

However, the decision to change to transient mode can be made simply by observation by the operator, and then the transient mode can be started manually, or one operation to determine the change to transient mode. It is also possible to pull out only the parameters.

For example, one or more of the following parameters are suitable as operating parameters for step 12 and / or for determination in step 13. It knocks on the actual pressure of the scavenging air available by the turbocharger system and / or changes in this pressure, cylinder pressure, calculated air-gas ratio, combustion in the cylinder. A recognizable knocking detector signal that means that the air-gas mixture becomes too rich, the ratio of torque to engine load or a change in this ratio, or the measured torque or time. That is the change.

The method according to the invention can also be used, among other things, for retrofitting existing large diesel engines, especially dual fuel engines. In such large diesel engines, the preconditions in terms of equipment for carrying out the methods according to the invention are often already met, or with less effort or cost, and / or by conversion. As it can be achieved, it is often possible to prepare a large diesel engine for transient mode with corresponding adaptations or engine control supplements. This possibility of retrofitting is extremely advantageous, especially considering the maintenance of emission values as well.

Claims (1)

A method of operating a large diesel engine, the large diesel engine can be operated in gas mode or transient mode, in which gas is introduced into the cylinder as fuel and in said transient mode. , In addition to the gas, liquid fuel is introduced into the cylinder, the method
-In the step (13) of changing the large diesel engine from the gas mode to the transient mode,
-The step of identifying the desired value of rotational speed or torque of the engine,
-Step (14) of determining the maximum amount of gas that can be used as fuel for each work cycle of the large diesel engine, and
-Additional amount of liquid fuel introduced into the cylinder in addition to the gas to compensate for the difference between the desired value of rotational speed or torque and the value achieved using the maximum amount of the gas. A method comprising determining step (14).

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