EP3156624A1 - Method for operating a slowly running large diesel engine, and slowly running large diesel engine - Google Patents

Abstract

The invention relates to a method for operating a slow-running large diesel engine (1), and a large diesel engine (1), comprising a cylinder liner (Z) with a combustion chamber (2) and an outlet valve (3) associated with the combustion chamber (2), wherein the combustion chamber (2) of the cylinder liner (Z) is connected to an exhaust manifold (41) and an exhaust manifold (4) comprehensive exhaust gas collection unit (40), and in the operating state in a combustion of a fuel (F) and a charge air (81) formed exhaust gas (5) from the combustion chamber (2) of the cylinder liner (Z) via the respective associated exhaust valve (3) and the respective associated exhaust port (41) is supplied to the exhaust manifold (4). Further, the large diesel engine (1) comprises a charging unit (7, 71) comprising a supercharging group (71) for compressing air (80) to which the exhaust gas (5) is supplied from the exhaust manifold (4), so that the charge by means of the supercharging group ( 71) compressed air (80) in the cylinder liner (Z) via a respective cylinder liner (Z) respectively associated scavenging air as charge air (81) can be initiated in the operating state. According to the invention, the exhaust gas collecting unit (40) comprises an exhaust gas probe (9) with which a characteristic value of a composition of the exhaust gas (5) is determined and, depending on the characteristic value in the combustion chamber (2), a ratio (L) of the charge air (81) with respect to the fuel (F) is set.

Description

The invention relates to a method for operating a slow-running large diesel engine, and a large diesel engine, in particular longitudinally flushed slow-running two-stroke large diesel engine according to the preamble of the independent claims.

A slow-running large diesel engine, in particular longitudinally flushed two-stroke large diesel engine Kreuzkopfbauart according to the present invention, as in a conventional manner preferred in shipbuilding or stationary systems, for example, to generate electrical energy for many decades in a variety of different variants in detail is used, comprises three large housing segments, which form the frame of the engine. On a base plate which has, in addition to a bearing saddle with crankshaft main bearing for receiving the crankshaft transversal support elements, separated by a bottom plate, a so-called stand arranged. The known stands comprise according to the number of cylinder liners of the large diesel engine a plurality of oppositely disposed support body, each having a vertically extending sliding surface for guiding two adjacent crossheads, which are connected via push rods to the crankshaft. In each case, two opposing perpendicularly extending support body with sliding surfaces by an intermediate wall in addition supported. The individual support bodies are usually connected to each other by a common cover plate. Above the stand then a cylinder section, often called cylinder jacket, is arranged on the cover plate, which is suitable for receiving a plurality of cylinder liners. The base plate, the stator and the cylinder section are connected by tie rods which extend in the region of the stator usually within the support body with each other by the tie rods are screwed in or on the base plate under considerable bias.

To increase the performance of reciprocating internal combustion engines, not only but especially for those of the type described above, after a combustion cycle fresh air by means of a Aufladegruppe, which usually comprises at least one exhaust gas turbocharger, introduced under increased pressure in the combustion chamber of a cylinder liner. As a result, part of the thermal energy of the exhaust gases can be utilized, which leave the combustion chamber of the cylinder liner after the combustion cycle. For this purpose, the hot exhaust gases from the combustion chamber of the cylinder liner of the Aufladegruppe be supplied by opening an opening provided for example in a cylinder cover of the cylinder liner exhaust valve. The Aufladegruppe consists essentially of a turbine which is driven by the incoming under pressure in the Aufladegruppe heated exhaust gases. The turbine in turn drives a compressor, whereby fresh air is sucked in and compressed. The compressor with turbine, an arrangement which is often referred to as a turbocharger in addition to the name turbocharger and especially, but not only, in the case of large diesel engines is usually designed as a radial compressor, is a so-called diffuser, a charge air cooler, a water separator and an inlet receiver downstream from where the compressed fresh air, also referred to as charge air or scavenging air, is finally fed into the individual combustion chambers of the cylinder liner of the large diesel engine. The use of such a charging group can thus increase the supply of fresh air and increase the efficiency of the combustion process in the combustion chamber of the cylinder.

In the case of large diesel engines, depending on the type, the air is supplied at different points on the cylinder liner. For example, in longitudinally purged two-stroke engines, the air in the form of charge air via scavenging slots, which are arranged in the tread in the lower region of the cylinder liner, introduced into the combustion chamber of the cylinder liner. In four-stroke engines, the charge air is typically provided via one or more intake valves, e.g. are arranged in a cylinder head or cylinder cover, introduced into the combustion chamber of the cylinder or cylinder liner. In this case, two-stroke engines are well known, which are equipped instead of scavenging slots in the lower region of the cylinder liner with the top of the cylinder liner, usually arranged in a cylinder cover intake valves.

Fig. 1 shows for a better understanding of the invention to be described later in a schematic representation to explain the interaction of the different components the basic structure of an exhaust system with exhaust gas turbocharger of a known from the prior art longitudinally flushed large diesel engine, which is referred to in the following throughout the reference numeral 1 ' becomes.

Based on Fig. 2 schematically is a modern special embodiment of a longitudinally-flushed long-running large diesel engine 1 'according to Fig. 1 in which in the exhaust system for the treatment of the exhaust gases additionally an exhaust gas reactor is provided with mixing pipe, wherein in the specific example of Fig. 2 the exhaust gas reactor is a so-called SCR reactor (Selective Catalytic Reduction) for the reduction of harmful nitrogen oxides, whose principal function will be explained in more detail below in cooperation with a large diesel engine 1 'below. That is, the known large diesel engine 1 'according Fig. 2 is different from the one in Fig. 1 shown schematically very large diesel engine 1 'essentially only in that the large diesel engine 1' according to Fig. 2 an exhaust gas reactor in the form of an SCR catalytic converter while in the somewhat simpler variant according to Fig. 1 no exhaust gas reactor is provided.

For better distinction of the invention from the prior art, reference numerals to features of examples which are known from the prior art, each provided with an apostrophe, while reference numerals, which relate to features of embodiments according to the invention, do not carry apostrophes.

The large diesel engine 1 'usually comprises, in a manner known per se, a cylinder group comprising one or more cylinder liners Z' with an exhaust valve 3 'arranged in a cylinder cover, in which cylinder liner Z' a piston K 'between a bottom dead center UT' and a top dead center OT 'is arranged back and forth along a tread. The cylinder walls of the cylinder liner Z 'with cylinder cover and piston K' limit in a known manner a combustion chamber 2 'of the cylinder liner Z'.

For clarity, is in Fig. 1 only a cylinder liner Z 'is shown by way of example. It is understood that in practice the cylinder group usually comprises a plurality, usually a plurality of cylinder liners Z 'as in the known large diesel engine 1' according to Fig. 2 for example, the case is.

In the lower region of the cylinder liner Z 'a plurality of scavenging air openings 9' are provided, which are designed as scavenging slots. Depending on the position of the piston K ', the flushing slots are covered or released by this. Due to the scavenging air openings 9 ', the charge air 81', which is often referred to as scavenging air, can flow into the combustion chamber 2 'of the cylinder liner Z'. By arranged in the cylinder cover exhaust valve 3 ', the resulting during combustion exhaust gases 5' flow through an exhaust manifold 4 ', which is flow-connected via the exhaust valves 3' in the open state via the exhaust port 41 'with the respective combustion chamber 2' in a configured as exhaust gas turbocharger Aufladegruppe 71 '. In the context of this application, the exhaust manifold 4 'and the exhaust pipe 41' by definition form the exhaust gas collection unit 40 '.

The turbocharger of Aufladegruppe 71 'comprises in a known manner as essential components a compressor with compressor impeller 711' for compressing air 80 ', and a turbine with a turbine impeller 712' for driving the compressor impeller 711 ', which in a known manner with an effective manner the turbine runner 712 'is connected. The turbine and the compressor are arranged in a housing and thus form the exhaust gas turbocharger, which is usually designed as a radial compressor. The turbine is driven in a known manner by the incoming heated exhaust gases 5 'from the combustion chamber 2' of the cylinder liner Z ', the exhaust gases 5' finally being discharged into the environment via an exhaust pipe 51 'designed as an exhaust after leaving the turbocharger.

For charging the combustion chamber 2 'of the cylinder liner Z' with charge air 81 'is sucked by the compressor impeller 711' air 80 'from the environment and compressed in the exhaust gas turbocharger. From the exhaust-gas turbocharger, the compressed air 80 'passes through the downstream diffuser 720' and the intercooler 730 'via the water separator 740' into an inlet receiver 750 ', from which the compressed air 80' finally as charge air 81 'through the scavenging air openings designed as rinsing slots 9 'passes under increased pressure in the combustion chamber 2' of the cylinder liner Z '.

Due to the ever stricter exhaust gas regulations, the requirements for the quality of the exhaust gases have been increasing steadily for some years, with not only, but in particular, the concentration of nitrogen oxides in the exhaust gases in the focus of emissions standards. Here, the legal requirements and limit values for the corresponding emission limits are being tightened. This has the consequence, in particular in large diesel engines, that the combustion of the classic, highly polluted with pollutants heavy oil, but also the combustion of diesel oil or other Fuels such as gas is becoming increasingly problematic, because the compliance with the exhaust limits is increasingly difficult, technically complex and therefore more expensive, or even to be feared that their compliance finally could no longer make sense.

In practice, therefore, enormous efforts have been made for some time with regard to the exhaust gas purification, keyword "catalytic converters" as well as with respect to alternative fuels. Therefore, i. Additionally or alternatively, the need for so-called "dual-fuel engines", ie engines that can be operated with two different fuels, has long existed for the same reason. In a gas mode, a gas, e.g. burned a natural gas such as LNG (liquefied natural gas) or a gas in the form of an autogas or other suitable for driving an internal combustion engine, while burned in a liquid mode, a suitable liquid fuel such as gasoline, diesel, heavy oil or other suitable liquid fuels in the same engine can be. The engines can be both two-stroke and four-stroke engines and it may be small, medium-sized but also large engines, especially also longitudinally purged two-stroke large diesel engines.

The term "large diesel engine" are thus in the context of this application in addition to the classic two-stroke large diesel engines and four-stroke Grossdiesselmotoren, which are operated with heavy oil or diesel oil, also meant such large engines, which except in diesel mode, which is characterized by the auto-ignition of the fuel also in a Otto operation, which is characterized by the spark ignition of the fuel, or can be operated in mixed forms of these two. Furthermore, the term "large diesel engine" also includes, in particular, the aforementioned dual-fuel engines and also those large engines in which the ignition of the fuel is initiated by means of spark ignition by another fuel.

In liquid mode, the fuel is usually introduced by means of an injection nozzle directly into the combustion chamber of the cylinder liner and burns there according to the principle of auto-ignition. In the gas mode, it is known according to the Otto principle to mix the gas in the gaseous state with the charge air so as to produce an ignitable mixture in the combustion chamber of the cylinder liner. In such an operating method, often referred to as a low-pressure method, the ignition of the mixture in the cylinder liner is usually carried out by injecting a small amount of liquid fuel into the combustion chamber of the cylinder liner or into an antechamber at the correct moment, which then ignites the air-gas mixture leads. A dual-fuel engine can often be switched from gas mode to liquid mode during operation and vice versa.

But even pure gas engines, ie engines that can only be operated with gas and not alternatively with diesel, heavy oil or other fuel, are in demand, especially when high exhaust standards are required, which makes economic sense with justifiable technical effort only by the combustion can be maintained by gas and thus may also be the subject of the invention described below below.

Regardless of whether it is a dual-fuel engine, a pure gas engine or an engine operated with a liquid fuel such as gasoline, diesel or heavy oil or mixed types from the aforementioned engine types, it will be essential in the future to use the appropriate exhaust gases To clean or treat plants and methods before the exhaust gases are released into the environment.

In particular, to reduce the nitrogen oxides in the exhaust gas, it is known to use exhaust gas reactors, in particular so-called "SCR reactors".

The term SCR is the English abbreviation for "Selective Catalytic Reduction" and can be colloquially referred to as a catalyst, which reduces the nitrogen oxides in the exhaust gas. Only this does not work as for example in the car with a platinum catalyst material but in the SCR reactor, the catalyst element consists for example of ceramic or metal and is provided with a special reactive coating. However, a reducing reaction occurs in conjunction with the coating only if the exhaust gas has previously been mixed with suitable chemical substances such as urea or ammonia, which must evaporate in the exhaust gas to ammonia.

For this mixture and evaporation, it is known from the prior art, before entering the SCR reactor, a certain length of a designed as a mixing and evaporation tube mixing section in the form of a mixing pipe between the exhaust pipe manifold and SCR reactor with a certain minimum length for the mixture and evaporation of the reagent, eg a urea, with the exhaust gases provided.

By way of example, the specific embodiment of a modern large diesel engine with an SCR exhaust gas reactor will be illustrated with reference to the schematic Fig. 2 , which shows a known from the prior art large diesel engine with exhaust manifold, mixing pipe, SCR reactor and Aufladegruppe in the event that only a single turbocharger is present. It is quite common, especially in large diesel engines with very many cylinder liners, such as 6, 8, 10, 12 or even with 14 cylinder liners that several Aufladegruppen and / or more exhaust gas reactors are provided with the associated modules.

The Fig. 2 shows in distinction to Fig. 1 a known large diesel engine 1 'with an exhaust gas collection unit 40' corresponding to the number of cylinder liners Z 'each an exhaust port 41' and a common exhaust manifold 4 ', and an exhaust gas reactor 6' and an associated mixing section 12 'in the form of a mixing pipe 121' in which the Exhaust gas 5 'is mixed with urea, for example, which evaporates in the exhaust gas 5' to ammonia. In addition, if a plurality of charging units 7 ', 71' are provided a in Fig. 2 no existing Abgasverteilrohr be installed, with which the effluent from the exhaust gas reactor 6 'exhaust 5' can be distributed to a plurality of charging units 7 ', 71', so that not for each charging unit 7 ', 71' a separate exhaust gas reactor 6 'itself must be provided , In even more modern large diesel engines 1 ', as recently proposed in several patent applications by the applicant, it is even possible that the exhaust manifold 4' and / or the mixing section 12 'and / or the exhaust gas reactor 6' and / or the Abgasverteilrohr in One or more modules are summarized so that not only saves valuable space and a higher mechanical stability against vibration loads and vibrations of all kinds can be achieved, but by shortening the exhaust lines and unnecessary pressure losses in the exhaust system are avoided, whereby the effectiveness of the charging units 7 ' , 71 'and thus ultimately the large diesel engine 1' can be increased overall.

Ultimately, of course, a problem closely associated with the exhaust gas purity is an optimal combustion of the fuel, which in turn is closely linked to the ratio of the charge air available for combustion in the combustion chamber of the cylinder liner with respect to the quantity of fuel available for a combustion process in the combustion chamber is.

In the known from the prior art slow running large diesel engines, the ratio of charge air to fuel in the cylinder liner from the pressure of the charge air and the opening duration of the fuel injectors by means of suitable look-up tables is roughly determined. The concrete pressure of the charge air is a function of the mean effective pressure and the rotational speed of the large diesel engine. The look-up table is essentially made manually from under laboratory conditions or during commissioning measured data obtained for the various operating conditions such as different Rotation speeds and / or the load in different operating conditions and / or taking into account the pressure of the charge air, and / or different fuel qualities or fuel types, such as gas, diesel, or heavy oil created.

In the operating state of the large diesel engine is then taking into account the current parameters that are considered in the look-up table and can be measured at least partially with suitable sensors in the operating state, determined by means of a controller, the ratio of fuel to charge air for all cylinders at the same time and adjusted by adjusting the amount of fuel provided to the combustion chamber of the cylinder liner per combustion stroke is adjusted accordingly. Since the amount of charge air under given operating conditions such. The setting of the ratio of fuel to charge air in the prior art usually by the fact that the opening time of a fuel injector is controlled accordingly, so that with a longer injection time correspondingly more fuel is injected per combustion cycle or the injection speed of the large diesel engine substantially at a shorter injection time correspondingly less.

The disadvantages of this known control method to adjust the ratio of charge air to fuel in a large diesel engine are obvious. Since the control technology is not a control (in the English close-loop control) but a control (in English open-loop control), unlike a control with a new setting of the ratio by the control no feedback considered be due to a change in an operating parameter or a state variable that occurred more or less spontaneously before the aforementioned setting of the ratio and that are not taken into account in the look-up table for a variety of reasons or in a look-up table in not be considered at all can. Such as a spontaneous change in pressure or temperature of the charge air or changes in parameters during combustion, changes in the air humidity of the charge air or changes due to fluctuations in the quality, eg chemical or physical properties of the fuel, lubricating oil, etc ..

A variety of other factors are known to those skilled in the art, which can affect the combustion behavior and therefore can influence the optimum ratio of charge air to fuel.

In the case of fast running small motors, i. Two-stroke or four-stroke Otto or diesel engines, the speeds of e.g. 1000 rpm (revolutions per minute) up to 6000rpm or even 12000rpm in racing engines for cars, motorcycles or racing boats with a relatively small displacement of usually a few 100 cubic centimeters (cc), the problem is already largely solved by using a so-called Lamda probe.

In the aforementioned small high-speed engines, the lambda probe is usually arranged in the exhaust manifold, which corresponds to the exhaust manifold in large diesel engines, or in the adjoining the exhaust manifold manifold leading to the exhaust. Here, averaged over all cylinders connected to the exhaust manifold and averaged over a plurality of revolutions of the engine, the lambda probe measures the residual oxygen content in the exhaust gas and compares this with the instantaneous oxygen content of the atmospheric air used for combustion of the fuel in the engine. From this, we determine the optimum ratio of combustion air to fuel and, at the same time, by means of a regulation of the supply of the combustion air and / or the fuel quantity, permanently adjust the same value for all cylinders.

With the fast running small engines all relevant processes are so fast and play themselves on the basis in the comparison to the Large diesel engines extremely small dimensions in such a limited space that an average over the proportion of oxygen content in the exhaust gases over all cylinders and also over several revolutions of the engine is quite sufficient. In addition, the fuel is usually introduced simultaneously into the combustion air for all cylinders at the same time in the case of small, high-speed engines, and the control of the ratio of charge air to fuel with evaluation of the lambda probe thus takes place simultaneously for all cylinders. The combustion behavior of a single cylinder or the average combustion behavior of all cylinders during a small number of revolutions of fast-running engines determines the overall composition and thus also the residual content of oxygen in the exhaust gas from a technical point of view. The operations in a single cylinder during a particular combustion cycle can not be measured separately, nor are they themselves technically relevant to the optimal operation of the engine.

With large diesel engines, the conditions are fundamentally different simply because of the enormous size of these engines.

Each cylinder liner can have an engine capacity of several cubic meters, eg with a cylinder bore of 1 m diameter and a stroke of 2.50 m, an enormously large displacement of up to 8 cubic meters. Correspondingly slow these engines also run. So maximum rotation speeds of eg 250rpm or 300rpm are quite common. In addition, the cylinder liners are thermally largely isolated from each other as described above, each cylinder liner has in a modern large diesel engine independently of the other cylinder liners controlled fuel injection, valve timing and cylinder lubrication. In addition, the various cylinder liners are often of different lengths in use, so that the involved parts such as pistons, piston rings, cylinder surfaces, etc. of the various cylinder liners in practice mostly in Different conditions of wear so that even under otherwise identical conditions, for example, a different combustion pressure or combustion temperature and thus can set a total between two cylinder liners combustion behavior.

Thus, the control concept described above with lambda probes, as has long been established in high-speed small engines, for large diesel engines is basically no option for the regulation of the ratio of charge air to fuel.

Starting from the prior art, it is therefore an object of the invention to provide an improved method for operating a slow-speed large diesel engine or such a large diesel engine, in particular to provide a slow-running longitudinally-flushed two-stroke or four-stroke large diesel engine, in which it is possible in a reliable manner , in each cylinder liner separately set an optimal ratio of charge air to Kraftsoff. Another object of the invention is to provide a reciprocating internal combustion engine, in particular two-stroke large diesel engine, with which fuel can be saved at a comparable load and the exhaust emissions can be reduced overall.

The objects of the invention solving these objects are characterized by the features of the independent claims.

The dependent claims relate to particularly advantageous embodiments of the invention.

The invention thus relates to a method for operating a slow-running large diesel engine, comprising a cylinder liner with a combustion chamber and an exhaust valve associated with the combustion chamber, wherein the combustion chamber of the cylinder liner with an exhaust nozzle and a Exhaust manifold exhaust comprehensive unit is connected to the exhaust manifold, and in the operating state, an exhaust gas formed in a combustion of a fuel and a charge air from the combustion chamber of the cylinder liner via the respectively associated exhaust valve and the respective associated exhaust port is supplied to the exhaust manifold. Further, a charging unit is provided including a Aufladegruppe for compressing air, which is supplied to the exhaust gas from the exhaust manifold, and compressed by means of the Aufladegruppe air in the cylinder liner via a respective cylinder liner each associated scavenging air is introduced as a charge air. According to the invention, the exhaust gas collecting unit comprises an exhaust gas probe with which a characteristic value of a composition of the exhaust gas is determined and a ratio of the charge air with respect to the fuel is set as a function of the characteristic value in the combustion chamber.

Essential to the invention is thus that the exhaust gas collecting unit comprises an exhaust gas probe, with which a characteristic value of a composition of the exhaust gas is determined and depending on the characteristic value in the combustion chamber, a ratio of the amount of charge air is adjusted with respect to the amount of fuel.

Thus, it is possible for the first time by the present invention, the inflexible static concept of adjusting the ratio of charge air to fuel in the combustion chamber of the cylinder liner used by the prior art so far for slow-speed large diesel engines alone by means of static look-up tables by a new innovative concept replace, which makes it possible for the first time to adjust the ratio of charge air to fuel in the cylinder liner dynamically to the actual, actually prevailing conditions in the combustion chamber of the cylinder liner or to the actual currently prevailing operating conditions or to the combustion decisive determining current parameters. This happens according to the invention in that by means of an exhaust gas probe in each case the current composition of the exhaust gas according to a predeterminable timing scheme, for example, continuously or in predetermined measuring distances again and again determined, so that by dynamic evaluation of the measurement results of the exhaust gas, the ratio of the charge air with respect to the fuel dynamically adjusted to any change in the combustion conditions in the combustion chamber can.

The invention is ultimately based on the finding that the fact that the individual cylinder liners of a slow-running large diesel engine, unlike the aforementioned small high-speed engines, at very low speeds of a few hundred revolutions per minute (rpm), usually even in continuous operation Only at about 100rpm to 150rpm and operated even at full load at barely more than 250rpm and these are usually not operable at higher RPM, even with relatively slow-measuring exhaust probes, eg Response times in the range of 5 ms or longer have, for example, with a known exhaust gas probe in the form of a broadband lambda probe, the exhaust emissions of individual cylinder liners can be determined separately.

As a further important criterion was recognized that the individual cylinder liners of a large diesel engine are of course coupled mechanically via the crankshaft, on the other hand thermally but more or less decoupled and also the individual cylinder liners and their components such as cylinder surfaces, pistons, piston rings, etc. usually in different Verschleisszuständen are, for example, because they are replaced or maintained at different times, so that even with otherwise thermodynamically comparable conditions, a combustion process with two different cylinder liners in one and the same large diesel engine can run significantly different, which among other things from the above is even the rule, so that a common, averaged over all cylinder liners evaluation of the exhaust gas quality, as they are basically only small fast running engines can be carried out and not least because of the strong thermal coupling of the cylinder of a small engine and the principle always comparable Verschleisszustands with small high-speed engines makes sense only in large diesel engines makes just no sense and for the aforementioned reasons would lead to useless measurement results ,

That is, it is an essential knowledge of the invention that the in itself e.g. Exhaust gas sensors known from the field of motor vehicles or exhaust gas sensors known from small ship engines, such as the well-known lambda probes, can also be advantageously used for slow-running large diesel engines, if only one other measuring method, ie a measuring method that differs substantially from that used with small fast-running engines, is used.

Thus, the widespread technical prejudice that a regulation of the quantity ratio of the charge air with respect to the fuel by means of an exhaust gas sensor, such as a known lambda probe is meaningfully not possible, ultimately refuted by the invention for the first time.

In practice, the method according to the invention is carried out by means of a slow-running large diesel engine, wherein the large diesel engine comprises a plurality of cylinder liners whose combustion chamber is flow-connected to the exhaust manifold via the respective associated exhaust valve such that in the operating state the exhaust gas from each combustion chamber is supplied to the exhaust manifold.

In a method according to the invention, the exhaust gas probe very particularly preferably determines the characteristic value of the composition of the exhaust gas separately for each cylinder liner, or the characteristic value of the composition of the exhaust gas can be determined separately for each cylinder liner from the measured data of the exhaust gas probe, so that, depending on the characteristic value for each cylinder liner each Cylinder liner individually an optimal ratio of the charge air in relation to the fuel can be set separately and individually.

In this case, the exhaust gas probe is arranged in practice particularly advantageous directly on or in the exhaust port of a cylinder liner, especially at several or all exhaust ports of the large diesel engine provided so that the exhaust gas probe essentially measures only the exhaust emissions from the combustion chamber of that cylinder liner, the corresponding exhaust port in the exhaust gas probe is arranged, is assigned. But it is also possible that the exhaust gas probe is provided on the exhaust manifold, in particular also that a plurality of exhaust gas probes are provided on the exhaust manifold.

In this case, the characteristic of the exhaust gas, which is determined by the one or more exhaust gas probes, and the e.g. may be provided in the exhaust manifold and / or in the exhaust port, are compared with a programmed example in a data processing system or calibration, and from the comparison with the calibration, the composition of the exhaust gas for a given cylinder liner, more preferably for all or more cylinder liners individually and be determined separately and set the ratio of the charge air with respect to the fuel for the combustion chamber of the given cylinder separately.

In this case, the characteristic value can be determined again and again by the exhaust gas probe according to a suitable predeterminable timing scheme, for example quasi continuously, in the same periodically recurring time intervals or according to another suitable timing scheme, and in the combustion chamber the ratio of the charge air with respect to the fuel as a function of the characteristic value in particular, with the additional use of a look-up table being updated or adjusted.

The person skilled in the art readily understands that the look-up table may contain further necessary data, such as information about the fuel used or the lubricating oil used, or information about the large diesel engine, such as its performance, number of cylinder liners or any other necessary information which is advantageous for determining the optimum ratio of charge air to fuel. Of course, further relevant measurement data such as temperature, pressure or humidity of the charge air, the speed or the current load of the large diesel engine or any other suitable operating parameters for determining the optimum ratio of charge air to fuel can be used, to determine the aforementioned additional relevant variables also suitable sensors for detecting these quantities may be provided at a suitable location on the large diesel engine in a manner known per se.

In practice, the characteristic value which is determined by the exhaust gas probe, particularly advantageously a residual oxygen amount in the exhaust gas and the exhaust gas probe determined according to the residual oxygen amount in the exhaust gas, the exhaust gas probe is particularly preferably a per se known lambda probe, in particular a broadband lambda probe ,

In this case, the quantity ratio of the charge air with respect to the fuel can be regulated, for example, by regulating the amount of charge air supplied into the combustion chamber. Measures for regulating the amount of charge air which can be introduced into the cylinder liner are known per se to the person skilled in the art. Thus, e.g. suitable controllable valves or flaps are provided on the scavenging slots or in the supply lines to or from the turbocharger or other structural measures known per se for regulating the amount of charge air supplied into the combustion chamber.

It is of course also possible to adjust the quantity ratio of charge air to fuel by regulating the amount of fuel supplied into the combustion chamber, for example by adjusting the duration of the charge Introducing eg the injection of the fuel by means of an injection nozzle in the combustion chamber is controlled accordingly, or for example in gas engines, the pressure of the combustion gas flowing into the combustion chamber is controlled accordingly or other suitable measures for controlling the amount of introduced into the combustion chamber fuel are determined, the Personnel are well known and therefore need not be discussed here in detail.

Of course, it is also possible to adjust both the amount of fuel and the amount of fuel introduced into the combustion chamber at the same time suitably or regulate.

The large diesel engine is thereby operated at a maximum speed of at most 300 rpm, in particular between 10 rpm and 200 rpm, preferably at a maximum speed between 30 rpm and 150 rpm and / or an exhaust gas probe with a response time of less than 10 ms, in particular with a response time of 2ms to 10ms, especially with a response time of about 5ms used. It is understood that the setting or regulation of the optimum ratio of charge air to fuel can be made better or more accurate, the slower the large diesel engine rotates or the smaller the response time of the exhaust probe, ie the time that the exhaust gas probe requires to make a reliable measurement is.

The invention further relates to a slow-running large diesel engine, in particular longitudinally flushed two-stroke or four-stroke large diesel engine for carrying out a method of the present invention, wherein an exhaust gas collector, in particular at an exhaust port and / or at an exhaust manifold of the large diesel engine an exhaust gas probe, in particular an exhaust gas probe Measurement of a residual oxygen content in the exhaust gas is provided.

The large diesel engine is in practice preferably at a maximum speed of 300rpm, especially between 70rpm and 200rpm, preferably at a maximum speed between 80rpm and 150rpm operable and / or the exhaust probe has a response time of less than 10ms, in particular a Response time from 2ms to 10ms, especially a response time of about 5ms.

Fig. 1

schematisch ein aus dem Stand der Technik bekannter längsgespülter Zweitakt-Grossdieselmotor;

Fig. 2

ein weiterer bekannter Grossdieselmotor mit SCR-Reaktor zur Abgasaufbereitung;

Fig. 3

ein Ausführungsbeispiel eines erfindungsgemässen Zweitakt-Grossdieselmotors mit SCR-Reaktor zur Abgasaufbereitung.

The invention will be explained in more detail below with reference to the drawing. In a schematic representation:

Fig. 1

schematically a longitudinally-flushed two-stroke large diesel engine known from the prior art;

Fig. 2

Another known large diesel engine with SCR reactor for the exhaust gas treatment;

Fig. 3

An embodiment of an inventive two-stroke large diesel engine with SCR reactor for the exhaust gas treatment.

The Fig. 1 and Fig. 2 refer to examples of the prior art, which have already been described in detail in the beginning and therefore need not be discussed again at this point.

The reciprocating internal combustion engine according to the invention, which is referred to in the following by the reference numeral 1, is designed in particular as a slow-running two-stroke or four-stroke large diesel engine with longitudinal scavenging, as is widely used, for example, in shipbuilding.

The Fig. 3 shows a specific embodiment of an inventive large diesel engine 1 in the form of a slow-running longitudinally flushed two-stroke large diesel engine 1, which is operated with heavy fuel oil. The large diesel engine 1 according Fig. 3 is a particularly modern Embodiment, which is already equipped with an SCR reactor 6 for reducing nitrogen oxides.

It goes without saying that a slow-running large diesel engine according to the invention does not necessarily have to be equipped with an exhaust gas catalytic converter. Also, of course, the invention relates to all types of slow-running large diesel engines. So both two-stroke and four-stroke large diesel engines, and large diesel engines that run on heavy fuel oil, diesel, gas or other suitable fuel, as well as so-called dual-fuel engines that can be operated alternatively or simultaneously with two different types of fuel, for example with Heavy or diesel oil and gas, as well as all other types of slow running large diesel engines, which are well known to those skilled in the art.

The slow-running longitudinally-flushed two-stroke large diesel engine 1 of Fig. 3 comprises in a conventional manner a cylinder liner Z with a combustion chamber 2 and the combustion chamber 2 associated exhaust valve 3, wherein the combustion chamber 2 of the cylinder liner Z is fluidly connected to an exhaust port 41 and an exhaust manifold 4 comprehensive exhaust gas collection unit 40, so that in the operating state in A combustion of a fuel F and a charge air 81 formed exhaust gas 5 from the combustion chamber 2 of the cylinder liner Z via the respective associated exhaust valve 3 and the respective associated exhaust port 41 to the exhaust manifold 4 can be fed. The highly modern special large diesel engine of Fig. 3 has an exhaust gas treatment in the form of an exhaust gas reactor 6, which is a known SCR reactor for the reduction of harmful nitrogen oxides in the exhaust gas 5. The exhaust gases 5 pass from the exhaust manifold 4 via the designed as a mixing pipe 121 mixing section 12 in the exhaust gas reactor 6 and are distributed from there via a Abgasverteilrohr 10 to the two turbochargers of the two Aufladegruppen 71. The charging unit 7 comprises a charging group 71 for compressing air 80, which in the operating state of the Turbochargers the Aufladegruppen 71 is sucked from the environment, wherein the compressed by means of the Aufladegruppe 71 air 80 into the cylinder liner Z via a each cylinder liner Z respectively associated, in Fig. 3 Invisible scavenging air opening is introduced as charge air 81. According to the invention, the exhaust gas collecting unit 40, here both in the exhaust pipe 41 and in the exhaust manifold 4, exhaust probes 9, with which a characteristic of a composition of the exhaust gas 5, here an amount of residual oxygen in the exhaust gas 5 is determined, so that in the operating state depending on the characteristic In the combustion chamber 2, a ratio L of the charge air 81 with respect to the fuel F can be optimally adjusted.

The skilled person understands that the invention is not limited to the explicitly discussed embodiments, but corresponding developments are likewise covered by the invention. In particular, the invention, of course, relates to all suitable combinations of the specific embodiments discussed.

Claims (15)

Method for operating a slow-running large diesel engine (1), comprising a cylinder liner (Z) with a combustion chamber (2) and an exhaust valve (3) associated with the combustion chamber (2), wherein the combustion chamber (2) of the cylinder liner (Z) with a Exhaust port (41) and an exhaust manifold (4) comprehensive exhaust gas collection unit (40) is fluidly connected, and in the operating state in a combustion of a fuel (F) and a charge air (81) formed exhaust gas (5) from the combustion chamber (2) of the cylinder liner (Z) via the respective associated exhaust valve (3) and the respective associated exhaust nozzle (41) is supplied to the exhaust manifold (4), and a charging unit (7, 71) comprising a Aufladegruppe (71) for compressing air (80) is provided to which the exhaust gas (5) from the exhaust manifold (4) supplied, and the compressed by means of the Aufladegruppe (71) compressed air (80) in the cylinder liner (Z) via a respective cylinder liner (Z) respectively associated scavenging air as Ladelu ft (81), characterized in that the exhaust gas collecting unit (40) comprises an exhaust gas probe (9) with which a characteristic value of a composition of the exhaust gas (5) is determined and in dependence on the characteristic value in the combustion chamber (2) a quantitative ratio (L) the charge air (81) is adjusted with respect to the fuel (F). The method according to claim 1, wherein the large diesel engine (1) comprises a plurality of cylinder liners (Z) whose combustion chamber (2) is flow-connected to the exhaust manifold (4) via the respective associated outlet valve (3) such that the exhaust gas (5 ) is supplied from each combustion chamber (2) to the exhaust manifold (4). Method according to one of claims 1 or 2, wherein the exhaust gas probe (9) determines the characteristic value of the composition of the exhaust gas (5) for each cylinder (Z) separately. Method according to one of the preceding claims, wherein depending on the characteristic value, the quantity ratio (L) of the charge air (81) with respect to the fuel (F) for each combustion chamber (2) is set separately. Method according to one of the preceding claims, wherein the exhaust gas probe (9) is provided on the exhaust nozzle (41), in particular at several or all exhaust nozzles (41) of the large diesel engine (1) an exhaust gas probe (9) is provided. Method according to one of the preceding claims, wherein the exhaust gas probe (9) is provided on the exhaust gas collecting pipe (4), in particular a plurality of exhaust gas probes (9) are provided on the exhaust gas collecting pipe (4). Method according to one of the preceding claims, wherein the characteristic value determined by one or more exhaust gas probes (9) is compared with a calibration, and from the comparison with the calibration, the composition of the exhaust gas (5) for a given cylinder liner (Z) is determined separately and the quantity ratio (L) of the charge air (81) with respect to the fuel (F) for the combustion chamber (2) of the predetermined cylinder liner (Z) is set separately. Method according to one of the preceding claims, wherein the characteristic value determined by one or more exhaust gas probes (9) is compared with a calibration, and from the comparison with the calibration the composition of the exhaust gas (5) for each cylinder cylinder (Z) of the large diesel engine (1) is determined separately, and the quantity ratio (L) of the charge air (81) with respect to the fuel (F) for the combustion chamber (2) of each cylinder liner (Z) of the large diesel engine (1) is set separately Method according to one of the preceding claims, wherein the characteristic value according to a predeterminable timing scheme, preferably in Periodic time intervals through the exhaust gas probe (9) again and again determined in the combustion chamber (2) the ratio (L) of the charge air (81) with respect to the fuel (F) in dependence on the characteristic value (K), in particular with additional use a look-up table is updated. Method according to one of the preceding claims, wherein the characteristic value is a residual amount of oxygen in the exhaust gas (5) and the exhaust gas probe (9) determines the residual oxygen quantity in the exhaust gas. Method according to one of the preceding claims, wherein the ratio (L) of the charge air (81) with respect to the fuel (F) by regulating the amount of charge air (81) fed into the combustion chamber (2) and / or by regulating the charge air the amount of fuel (F) supplied to the combustion chamber (2) is adjusted. Method according to one of the preceding claims, wherein the large diesel engine (1) at a maximum speed of at most 300rpm, in particular between 10rpm and 200rpm, preferably at a maximum speed between 30rpm and 150rpm is operated. Method according to one of the preceding claims, wherein an exhaust gas probe (9) with a response time of less than 10 ms, in particular with a response time of 2 ms to 10 ms, in particular with a response time of about 5 ms is used. Slow-running large diesel engine, in particular longitudinally-flushed two-stroke or four-stroke large diesel engine for carrying out a method according to one of the preceding claims, wherein at an exhaust gas collecting unit (4), in particular at an exhaust port (41) and / or at an exhaust manifold (4) of the large diesel engine Exhaust probe (9), in particular an exhaust gas probe (9) for measuring a residual oxygen content in the exhaust gas (5) is provided. Large diesel engine according to claim 13, wherein the large diesel engine at a maximum speed of at most 300rpm, in particular between 70rpm and 200rpm, preferably at a maximum speed between 80rpm and 150rpm is operable and / or wherein the exhaust gas probe (9) has a response time of less than 10ms, in particular a response time of 2ms to 10ms, in particular a response time of about 5ms has.

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