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CN-122014434-A - Method for operating a large engine and large engine

CN122014434ACN 122014434 ACN122014434 ACN 122014434ACN-122014434-A

Abstract

The invention relates to a method for operating a large engine and a large engine. The large engine (20) comprises at least one cylinder (21) having a combustion chamber delimited by a piston (23) movable back and forth along a cylinder axis. The air-fuel mixture is compressed in the combustion chamber by the movement of the piston (23) at a compression ratio, and the operating parameters of the large engine (20) are determined continuously or at regular intervals. An optimal compression ratio for the air-fuel mixture is determined based on the operating parameter, and the compression ratio is adjusted to the optimal compression ratio.

Inventors

  • HANS TOBIAS
  • M o Krol
  • R. Glazer

Assignees

  • 温特图尔汽柴油公司

Dates

Publication Date
20260512
Application Date
20200428
Priority Date
20190603

Claims (16)

  1. 1. A method of operating a large engine, the large engine (20) comprising at least one cylinder (21), the at least one cylinder (21) having a combustion chamber delimited by a piston (23), the piston (23) being movable back and forth along a cylinder axis, wherein an air-fuel mixture is compressed in the combustion chamber via movement of the piston (23) with a compression ratio, and wherein operating parameters of the large engine (20) are determined continuously or at regular intervals, characterized in that an optimal compression ratio for the air-fuel mixture is determined based on the operating parameters and the compression ratio is adapted to the optimal compression ratio.
  2. 2. The method of claim 1, wherein the compression ratio is controlled in accordance with the operating parameter.
  3. 3. The method of claim 1, wherein the compression ratio is adjusted according to the operating parameter.
  4. 4. A method according to any one of the preceding claims, wherein the air-fuel ratio is adjusted such that the air-fuel ratio is between a knock limit (3) and a misfire limit (4).
  5. 5. The method according to any of the preceding claims, wherein the large engine (20) further comprises a rotatable crankshaft and the piston (23) is connected to a crosshead via a piston rod and the crosshead is connected to the crankshaft via a thrust rod, wherein the compression ratio is changed by displacing the piston rod and/or the piston relative to the crosshead.
  6. 6. A method according to any preceding claim, wherein the operating parameter is engine load and/or rotational speed.
  7. 7. The method of any one of claims 1 to 6, wherein the operating parameter is an ignition ratio and the ignition ratio is constant or dependent on engine load and/or rotational speed.
  8. 8. The method according to any one of claims 1 to 7, wherein the operating parameter is an ignition pressure, and the ignition pressure is in particular constant or dependent on an engine load and/or a rotational speed.
  9. 9. The method according to any one of claims 1 to 8, wherein the operating parameter is an ignition pressure increase, and the ignition pressure increase is in particular constant or dependent on an engine load and/or a rotational speed.
  10. 10. The method according to any one of claims 1 to 5, wherein the operating parameter is an emission parameter, and the emission parameter is in particular constant or dependent on engine load and/or rotational speed.
  11. 11. The method according to any of the preceding claims, wherein the operating parameter is a transient behavior, which is a load change or a rotational speed change, and wherein the compression ratio is adjusted according to the operating parameter.
  12. 12. The method according to any of the preceding claims, wherein the large engine (20) is operated in a gas mode.
  13. 13. A method according to any one of the preceding claims, wherein the operating parameter is detected continuously or at regular intervals by a sensor, and the sensor is a virtual sensor or a real sensor.
  14. 14. A large engine, characterized in that the large engine (20) is operated according to the method according to any one of the preceding claims.
  15. 15. A large engine according to claim 14, comprising at least one cylinder (21) with a combustion chamber delimited by a piston (23) arranged to be movable back and forth along a cylinder axis, and a rotatable crankshaft and inspection device, wherein the piston (23) is connected to a crosshead via a piston rod and the crosshead is connected to the crankshaft via a thrust rod, and the inspection device comprises a thrust device capable of displacing the position of the piston rod and/or the piston (23) relative to the crosshead.
  16. 16. A large engine according to claim 14 or 15, designed as a dual fuel large diesel engine, which is operable in a liquid mode in which liquid fuel is introduced into the combustion chamber for combustion, and which is further operable in a gas mode in which gas is introduced into the combustion chamber.

Description

Method for operating a large engine and large engine The application is a divisional application of patent application with the application number of 202010349046.X, the application name of 'method for operating large engine and large engine' of 28 months of 2020. Technical Field The present invention relates to a method for operating a large engine having at least one cylinder, and to a large engine. Background Large engines, which may be designed as two-stroke or four-stroke engines (e.g. longitudinally scavenged two-stroke large diesel engines), are often used as drive units for ships or even in stationary operation, e.g. for driving large generators for generating electrical energy. Engines are typically operated in continuous operation for a considerable period of time, which places high demands on operational safety and usability. Thus, particularly long maintenance intervals, low wear and economical handling of the operating material are central criteria for the operator. Large engines typically have cylinders with an internal diameter (cylinder bore) of at least 200 mm. Today, large engines with cylinder bores up to 960mm or even larger are used. Different types of large engines are known, each of which can be designed as a two-stroke or four-stroke engine. Regarding economical and efficient operation, compliance with exhaust emission thresholds and availability of resources, alternatives to heavy fuel oil or diesel oil traditionally used as large engine fuel are also being sought. In this respect, two liquid fuels are used, namely the fuel introduced into the combustion chamber in the liquid state, and a gaseous fuel, namely the fuel introduced into the combustion chamber in the gaseous state. Examples of liquid fuels as known alternatives to heavy fuel oils are other heavy hydrocarbons from petroleum refineries, alcohols, in particular methanol or ethanol, gasoline, diesel or also emulsions or suspensions. For example, an emulsion called MSAR (multiphase ultrafine atomized residue) is known to be used as a fuel. The well known suspension is a suspension of coal dust and water, which is also used as fuel for large engines. Natural gas such as LNG (liquefied natural gas) or LPG (liquefied petroleum gas) is called a gaseous fuel. Another well-known alternative to pure operation with heavy fuel oil is to design large engines so that they can be operated with two or even more different fuels, where the engine is operated with either one fuel or the other, depending on the operating conditions or circumstances. Such large engines, also known as multi-fuel large engines, may be switched from a first mode in which a first fuel is combusted to a second mode in which a second fuel is combusted during operation, and vice versa. Large engines that can be operated simultaneously with at least two different fuels are also known. Two different fuels may be combusted simultaneously in one or more cylinders, or only a first fuel may be combusted in a first group of cylinders while only a second fuel, different from the first fuel, may be combusted in another group of cylinders. A known design of large engines that can be operated with two different fuels is the type of engine that currently uses the term "dual fuel engine". These engines may operate in a gas mode in which a gaseous fuel, such as natural gas or methane, is introduced into the combustion chamber for combustion, on the one hand, and in a liquid mode in which a liquid fuel, such as heavy fuel oil or another liquid fuel, may be combusted in the same engine, on the other hand. These large engines may be two-stroke and four-stroke engines, in particular also longitudinally scavenged two-stroke large diesel engines. Large engines that can be operated with at least two or even more different liquid or gaseous fuels are often operated in different modes depending on the fuel currently being used. In a mode of operation commonly referred to as diesel operation, combustion of fuel generally occurs according to the principles of compression ignition or auto-ignition of the fuel. In a mode commonly referred to as otto operation, combustion occurs through spark ignition of an ignitable premixed air-fuel mixture. The spark ignition may be performed, for example, by an electric spark using a spark plug, or may also be performed by spontaneous combustion of a small amount of injected fuel, which then causes spark ignition of another fuel. A small amount of fuel for auto-ignition is typically injected into a prechamber connected to the combustion chamber. For example, with the above dual fuel engine, it is known for the gas mode that gaseous gases are mixed with scavenging air in order to produce a combustible mixture in the combustion chamber of the cylinder. During this low pressure process, the mixture in the cylinder is typically ignited by injecting a small amount of liquid, auto-ignition fuel into the combustion or pre-combustion chamber of the cylinder at the