阅读说明：本技术 用于大型发动机的气缸装置以及冷却方法 (Cylinder device for large engine and cooling method ) 是由 D·斯特罗戴克 U·巴尔西杰 于 2020-01-16 设计创作，主要内容包括：用于大型发动机的气缸装置以及冷却方法。本发明涉及一种用于大型发动机的具有气缸衬套和气缸盖的气缸装置。气缸装置具有冷却回路,该冷却回路以这样的方式连接到第一冷却入口、第二冷却入口、第一冷却出口和第二冷却出口,即,冷却流体能够从第一冷却出口被引导到第一冷却入口和第二冷却入口,其中,可控的混合阀布置在第一冷却出口和第一冷却入口之间的冷却回路中。循环泵布置在在混合阀和第一冷却入口之间的冷却回路中,用于使冷却流体从第一冷却出口再循环到第一冷却入口。混合阀流动连接到循环泵、第一冷却出口和用于供应新鲜冷却流体的冷却流体供应部,其中,混合阀被设计成使得冷却流体的可再循环量能够被调节。(A cylinder device for a large engine and a cooling method. The present invention relates to a cylinder device having a cylinder liner and a cylinder head for a large engine. The cylinder arrangement has a cooling circuit which is connected to the first cooling inlet, the second cooling inlet, the first cooling outlet and the second cooling outlet in such a way that cooling fluid can be conducted from the first cooling outlet to the first cooling inlet and the second cooling inlet, wherein a controllable mixing valve is arranged in the cooling circuit between the first cooling outlet and the first cooling inlet. A circulation pump is arranged in the cooling circuit between the mixing valve and the first cooling inlet for recirculating the cooling fluid from the first cooling outlet to the first cooling inlet. The mixing valve is flow-connected to the circulation pump, the first cooling outlet and the cooling fluid supply for supplying fresh cooling fluid, wherein the mixing valve is designed such that the recyclable quantity of cooling fluid can be adjusted.)

1. A cylinder arrangement for a large engine, in particular a longitudinally scavenged two-stroke large diesel engine, comprising a cylinder liner (2) and a cylinder head (3), wherein a piston is mountable in the cylinder liner (2), which piston is arranged to be movable back and forth between an upper dead center and a lower dead center along a cylinder axis (X) of the cylinder liner (2) in an operating state in such a way that an upper side of the piston, together with a running surface of the cylinder liner (2) and the cylinder head (3) arranged on the cylinder liner (2), delimits a combustion chamber, wherein the cylinder liner (2) comprises a first cooling inlet (E1) for supplying cooling fluid into the cylinder liner (2) and a first cooling outlet (A1) for discharging the cooling fluid from the cylinder liner (2), and the cylinder head (3) comprising a second cooling inlet (E2) for supplying the cooling fluid into the cylinder head (3) and a second cooling outlet (A2) for discharging the cooling fluid from the cylinder head (3), wherein the cylinder arrangement (1) comprises a cooling circuit (100), which cooling circuit (100) is connected to the first cooling inlet (E1), the second cooling inlet (E2), the first cooling outlet (A1) and the second cooling outlet (A2) in such a way that the cooling fluid can be conducted from the first cooling outlet (A1) to the first cooling inlet (E1) and the second cooling inlet (E2), wherein a controllable mixing valve (V1) is arranged in the cooling circuit (100) between the first cooling outlet (A1) and the first cooling inlet (E1), wherein a circulation pump (P1) is arranged in the cooling circuit (100) between the mixing valve (V1) and the first cooling inlet (E1) for recirculating the cooling fluid from the first cooling outlet (A1) to the first cooling inlet (E1), wherein the mixing valve (V1) is flow-connected to the circulation pump (P1), the first cooling outlet (A1) and a cooling fluid supply (5) for supplying fresh cooling fluid, and wherein the mixing valve (V1) is designed in such a way that the recirculation amount of the cooling fluid can be adjusted.

2. A cylinder arrangement according to claim 1, wherein the mixing valve (V1) is designed as a three-way valve (V1) or as a combination of two-way valves.

3. Cylinder arrangement according to any of the preceding claims, comprising a control system (4), by means of which control system (4) the mixing valve (V1) can be controlled in such a way that the recyclable quantity of the cooling fluid can be adjusted.

4. A cylinder device according to claim 3, wherein the mixing valve (V1) is controllable by the control system (4) in such a way as to interrupt the recirculation of the cooling fluid from the first cooling outlet (a1) to the first cooling inlet (E1).

5. A cylinder device according to any one of claims 3 or 4, wherein a first temperature sensor (S1) is arranged on the cooling circuit (100) in the flow direction behind the first cooling outlet (A1), and the first temperature sensor (S1) is connected to the control system (4) in such a way that the amount of recirculation of the cooling fluid can be adjusted according to the temperature of the cooling fluid measurable by the first temperature sensor (S1).

6. A cylinder device according to any one of the foregoing claims, wherein the second cooling inlet (E2) is connected to the cooling fluid supply (5) via the cooling circuit (100) to supply fresh cooling fluid.

7. A cylinder arrangement according to any one of the foregoing claims, wherein a compensation line (6) is arranged between the second cooling inlet (E2) and the cooling fluid supply (5), with which compensation line the amount of cooling fluid recirculated to the first cooling inlet (E1) can be compensated for.

8. A cylinder arrangement according to any one of the preceding claims, wherein a liner cooling system (21) is arranged in the cylinder wall of the cylinder liner (2) and a head cooling system (31) is arranged in the cylinder head (3).

9. A cylinder device according to any one of the preceding claims, wherein the circulation pump (P1) is a propeller pump or a centrifugal pump.

10. A cylinder device according to any of the preceding claims, wherein the cooling fluid is oil and/or water, in particular sea water and/or drinking water and/or fresh water.

11. A cylinder arrangement according to any one of the preceding claims, wherein the cooling circuit (100) is designed as a closed circuit and can be recooled with a recooling fluid, in particular with low-temperature cooling water.

12. A cylinder device according to claim 11, comprising a heat exchanger or mixing device for cooling the cooling fluid.

13. A large engine comprising a cylinder arrangement (1) according to any one of the preceding claims.

14. Large engine according to claim 13, wherein the large engine is designed as a dual-fuel large diesel engine.

15. Method for cooling a cylinder of a large engine comprising a cylinder arrangement (1) according to any one of claims 1-12, wherein the amount of recirculation of the cooling fluid is adjusted via a controllable mixing valve (V1).

Technical Field

The present invention relates to a cylinder arrangement for a large engine, a large engine with a cylinder arrangement according to the invention and a method for cooling a large engine with a cylinder arrangement according to the invention.

Background

Large engines that can 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 for stationary operations, e.g. for driving large generators to produce electrical energy. The engine is usually operated in continuous operation for a considerable time, which puts high demands on operational safety and availability. Therefore, particularly long maintenance intervals, low wear and economical disposal of operating materials are central criteria for operators. Large engines typically have cylinders with an internal diameter (bore) of at least 200 mm. Today, large engines with holes up to 1000mm or even larger are used.

Different types of large engines are known, each of which may be designed as a two-stroke or four-stroke engine. With respect to economical and efficient operation, compliance with exhaust emission thresholds and availability of resources, alternatives to heavy fuel oils, which are traditionally used as fuels for large engines, are also being sought. In this regard, both liquid fuel (i.e., fuel introduced into the combustion chamber in a liquid state) and gaseous fuel (i.e., fuel introduced into the combustion chamber in a gaseous state) are used.

Examples of liquid fuels are heavy fuel oils of various quality grades, kerosene, diesel and gasoline, alcohols (in particular methanol or ethanol), biologically produced fuels (biofuels) (e.g. FAME, which is partly mixed with the above conventional fuels, or also emulsions or suspensions). For example, emulsions known as MSAR (multi-phase ultra fine atomized residue) are known for use as fuels. A well-known suspension is a suspension of coal fines and water, which is also used as fuel for large engines. Natural gas such as LNG (liquefied natural gas), ethane and propane are called gaseous fuels, for example in a mixture as LPG.

Another well known alternative to operating with only heavy fuel oil or with only another petroleum based fuel is to design large engines so that they can operate with two or more different fuels, where the engines operate with one fuel or another depending on the operating conditions or circumstances. Such large engines, also referred to as multi-fuel large engines, may switch during operation from a first mode in which a first fuel is combusted to a second mode in which a second fuel is combusted, or may switch from the second mode in which the second fuel is combusted to the first mode in which the first fuel is combusted. Furthermore, it is also possible that the large engine operates on two fuels simultaneously. For example, both the first fuel and the second fuel may be injected into one or more cylinders such that the combustion process is based on both combustion of the first fuel and combustion of the second fuel ("fuel sharing"). However, it is also possible that the first number of cylinders is operated with only the first fuel while the second number of cylinders is operated with only the second fuel.

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". On the one hand, these engines can be operated in gas mode (in which a gaseous fuel, such as natural gas, methane, ethane, propane or a low flash point liquid LFL, such as methanol, ethanol, LPG or DME, for example) is introduced into the combustion chamber for combustion, and on the other hand, these engines can be operated in liquid mode (in which a liquid fuel, such as a heavy fuel oil or another liquid fuel, for example, can be combusted in the same engine). Further, it is also possible for a dual fuel engine to operate in a hybrid mode using both fuels simultaneously. These large engines may be two-stroke and four-stroke engines, in particular also longitudinally scavenged two-stroke large diesel engines.

It is known that the load to which the cylinder liner is subjected in the operating state is particularly high in the upper region of the cylinder liner, i.e. the portion of the piston which passes near the cylinder head at top dead center in the operating state. Near the top dead center position of the piston (i.e., when the volume of the combustion chamber enclosed by the cylinder liner, cylinder head, and piston is approximately minimal), the air-fuel mixture ignites, or ignites itself. This leads to high temperatures and pressures in the cylinder liner, which are also subject to strong dynamic changes, in particular due to the movement of the piston and the constantly changing volume of the combustion chamber.

It has therefore long been known, for example, to provide a cooling ring at the upper end of the cylinder liner close to the cylinder head, which cooling ring is preferably equipped with water cooling means so that at least part of the generated heat load can be conducted away from the cylinder liner via the cooling ring. Since the largest part of the heat generated in the cylinder so far occurs in the upper region of the cylinder liner and thus also on the cylinder head, in the cylinder arrangements known from the prior art the temperature in the upper region of the cylinder liner is significantly higher than in the lower region of the cylinder liner. This means that in the cylinder liners known in the prior art, there is a large temperature gradient along the cylinder axis in the cylinder wall of the cylinder liner. In other words, the temperature in the upper part of the wall of the cylinder liner, in particular in the part adjacent to the cylinder head, is too high compared to the desired average temperature value, whereas the temperature in the lower part of the cylinder liner is relatively too low.

This has several very different negative effects known to the person skilled in the art. Due to the significantly different temperatures in different regions of the wall of the cylinder liner, there are naturally corresponding internal mechanical distortions. For example, if no additional measures are taken, the upper region of the cylinder liner in the vicinity of the cylinder head expands radially more than the lower region of the cylinder liner. This means that there is a risk that the inner diameter of the upper region of the cylinder liner is larger than the inner diameter of the lower region in the operating state of a large engine. This leads not only to the disadvantage that the piston running characteristics of the piston are known per se, and thus to an increased friction between the piston and the running surface of the liner, but of course also to corresponding internal stresses in the material of the cylinder liner in the radial direction and in relation to the axial direction along the cylinder axis. Large temperature gradients naturally also lead to accelerated or more intense and inhomogeneous corrosion processes in the cylinder liners of the machine components involved.

For example, if during operation with high sulfur fuel (e.g., heavy fuel oil or diesel), the cylinder liner is cooled so aggressively that even at full engine load, the upper region of the cylinder liner does not become overheated, which can lead to the fact that during part load operation the dew point in the cooler lower region of the cylinder liner drops below the existing pressure level. This leads to the formation of acids, in particular sulfurous acid and sulfuric acid.

Thus, the formation of harmful acids and, for example, cold corrosion may thus be favoured or adversely affected by the temperature distribution in the cylinder liner. The list of the above mentioned detrimental effects should only be understood as an example and is by no means exhaustive. Many other negative consequences will be readily apparent to those skilled in the art.

EP 2848786 a1 discloses a cooling arrangement in which in each case an own separate cooling system is provided for the cylinder head and the cylinder liner, and in which, in the event of flow exchange between the liner cooling fluid and the head cooling fluid being prevented, there is no mixing of the cooling medium of the head cooling system with the cooling medium of the liner cooling system.

In the prior art, it is also known to have a cooling circuit for a common cooling circuit for the cylinder liner and the cylinder head. Here, the cooling fluid is conducted from the cylinder liner into the cylinder head. The pump and check valve may be used to regulate whether the cooling fluid that has been used (i.e., heated) is recirculated (i.e., whether the cooling fluid exiting the cylinder liner is partially returned to the cooling fluid inlet of the cylinder liner). Such recirculation of the cooling fluid is used in particular for part-load operation of the engine, wherein a pump is used for recirculation, which pump is activated for recirculation of the cooling fluid. A disadvantage of this arrangement is that once the pump is shut down, damage to the pump due to downtime (damage due to idle time) can occur. The pump is only used for partial load operation and is turned off for full load operation.

With the cylinder arrangements known from the prior art, it is therefore not only possible to anticipate a considerable reduction in the service life of the components involved, such as the cylinder liner itself or at least the running surfaces of the cylinder liner, the piston rings, the piston, the cylinder head and the components arranged there, such as the nozzles, the outlet valves, the hydraulic valves, the pumps and the devices, etc., but also to anticipate power losses during operation of the engine, resulting in an increase in fuel consumption and, ultimately, in higher overall costs and a deterioration in operating efficiency.

Disclosure of Invention

The object of the present invention is therefore to propose a cylinder arrangement which avoids the known disadvantages of the prior art. Furthermore, it is an object of the present invention to propose an improved large engine which avoids the known disadvantages of the prior art. Another object of the present invention is to propose an improved method for cooling large engines which avoids the known drawbacks of the prior art.

The invention thus relates to a cylinder arrangement for a large engine, which may in particular be a longitudinally scavenged two-stroke large diesel engine. Here, the cylinder device includes a cylinder liner and a cylinder head. The piston may be mounted in a known manner in a cylinder liner, which in the operating state is arranged so as to be movable back and forth along the cylinder axis of the cylinder liner between a top dead center and a bottom dead center in such a way that the upper side of the piston, together with the running surface of the cylinder liner and a cylinder head arranged on the cylinder liner, delimits a combustion chamber. The cylinder liner has a first cooling inlet for supplying cooling fluid into the cylinder liner and a first cooling outlet for exhausting cooling fluid from the cylinder liner. The cylinder head has a second cooling inlet for supplying cooling fluid into the cylinder head and a second cooling outlet for discharging cooling fluid from the cylinder head. Furthermore, the cylinder arrangement comprises a cooling circuit connected to the first cooling inlet, the second cooling inlet, the first cooling outlet and the second cooling outlet in such a way that cooling fluid can be conducted from the first cooling outlet to the first cooling inlet and the second cooling inlet. Thus, the cooling fluid may be guided to the cylinder liner and the cylinder head by means of the cooling circuit in the operating state in order to cool them to a predeterminable temperature or to allow the cooling water to be heated to a predeterminable temperature. To this end, a controllable mixing valve is arranged in the cooling circuit between the first cooling outlet and the first cooling inlet, whereby a circulation pump is arranged in the cooling circuit between the mixing valve and the first cooling inlet for recirculating the cooling fluid from the first cooling outlet to the first cooling inlet. In this case, the mixing valve is fluidly connected to the circulation pump, the first cooling outlet and a cooling fluid supply for supplying fresh cooling fluid and designed such that the recyclable quantity of cooling fluid can be adjusted.

It is therefore important for the invention that the mixing valve can be adjusted in such a way that the cooling fluid supplied to the first cooling inlet of the cylinder arrangement can preferably be a mixture of fresh cooling fluid and recirculated cooling fluid in a predeterminable proportion, preferably with a temperature-controlled adaptation of the quantitative ratio, depending on the operating conditions, in particular full or partial load, low-sulfur or sulfur-free or high-sulfur operation.

Fresh cooling fluid refers to cooling fluid which is not cold from the first cooling outlet of the cylinder liner, i.e. is not cooling fluid which was previously heated in the cylinder liner, but is cooling fluid originating from a cooling fluid supply and is cooled, for example via a heat exchanger or supplied from a reservoir.

In particular, a flexible adjustment of the operating temperature, in particular depending on the operating state, can be achieved by means of the invention. In the cylinder device according to the present invention, the operating temperature may be adjusted via the cooling fluid or via the amount of the cooling fluid recirculated from the first cooling outlet to the first cooling inlet. The temperature of the cooling fluid, in particular the cooling fluid in the cylinder liner, can easily be adjusted, regulated or controlled by means of an adjustable mixing valve. In this way, excessive cooling of the cylinder liner, which can lead to the formation of corrosive substances, such as sulfurous acid or sulfuric acid, can be avoided during part load operation, particularly with sulfur-containing fuels.

Thanks to the device according to the invention, damage caused by the stoppage of the circulation pump (damage due to idle time) can be avoided, since the circulation pump can be used permanently in the operating state, i.e. in the case of running of the engine, without having to be shut down by the device with the mixing valve.

In a particularly preferred embodiment, the mixing valve can be designed as a three-way valve, in particular as a three-way mixer. Like the switching valve, the three-way mixer has three connections and is preferably switched as follows: one connection is connected to the circulation pump; one connecting portion is connected to the cooling fluid supply portion; a connection is connected to the first cooling outlet to enable recirculation of at least a portion of the cooling fluid exiting from the first cooling outlet. The three-way mixer preferably has two extreme positions: an open position in which the cooling fluid directed to the first cooling inlet originates entirely from the cooling fluid supply, i.e. the recirculation of cooling fluid from the first cooling outlet to the first cooling inlet is closed; and a closed position in which cooling fluid exiting the first cooling outlet is fully recirculated to the first cooling inlet. The three-way mixer can be adjusted between these two extreme positions as required, so that the amount of cooling fluid recirculated from the first cooling outlet to the first cooling inlet can be adjusted. In embodiments of the invention, the open position or an intermediate position between the open position and the closed position is preferred for a mixture of fresh cooling fluid and recirculated cooling fluid. The intermediate position with the mixture of fresh cooling fluid and recirculated cooling fluid may be adjusted or controlled to different mixing ratios of fresh cooling fluid and recirculated cooling fluid depending on the operating conditions, for example to achieve a predetermined temperature at the first cooling outlet. The mixing valve provided according to the invention can of course also be designed as a four-way mixer or any multi-way valve.

In particular, it is also possible to design the mixing valve as a combination of two-way valves. In this case, one of the two-way valves is used to adjust the amount of cooling fluid that is recirculated from the first cooling outlet to the first cooling inlet. The other two-way valve is used to adjust the amount of fresh cooling fluid.

In practice, a controllable mixing valve may be controlled via a control system in the following way: the amount of recirculation of the cooling fluid can be adjusted. Thus, via control of the mixing valve, the mixture of recirculated cooling fluid and fresh cooling fluid supplied to the first cooling inlet may be adjusted as desired. Here, the control system may be embodied as a controller comprising an electronic unit or as a computer-implemented device controlling the mixing valve. As already described above, the mixing valve can also be controlled by the control system in the following way: the recirculation of cooling fluid from the first cooling outlet to the first cooling inlet is prevented or avoided such that only fresh cooling fluid is supplied to the first cooling inlet.

Control of the mixing valve need not be performed manually. Preferably, the cylinder device according to the invention comprises a sensor, so that an automatic control can be realized at least to a large extent. In particular, the first temperature sensor can be arranged on the cooling circuit downstream of the first cooling outlet in the flow direction. The first temperature sensor is preferably arranged in the vicinity of the first cooling outlet at a point upstream of the branch which can supply cooling fluid on the one hand to the first cooling inlet and on the other hand to the second cooling inlet. The temperature sensor may be connected to the control system as follows: the amount of recirculation of the cooling fluid is adjusted or can be adjusted (in particular can be adjusted or controlled) depending on the temperature of the cooling fluid measured by the first temperature sensor.

Furthermore, a second temperature sensor may be arranged on the cooling circuit after the second cooling outlet in the flow direction in order to detect the temperature of the cooling fluid at or adjacent downstream of the second cooling outlet. The temperature detected by the second temperature sensor is preferably used to regulate the temperature of the fresh coolant to a predeterminable value. This is a preferred embodiment if the temperature detected by the second temperature sensor has no direct effect on the amount of cooling fluid recirculated, but is only used to adjust or regulate the temperature of the fresh coolant. In practice, a fixed temperature range or a fixed temperature, in particular 60 to 100 ℃, preferably approximately 80 ℃ to 90 ℃, is preferably predetermined for the temperature detected by the second temperature sensor.

In an embodiment of the invention, the second cooling inlet may be connected via a cooling circuit to a cooling fluid supply for supplying fresh cooling fluid. By means of such an arrangement, a uniform volume flow through the cylinder arrangement can be achieved, since, for example, via the compensating line, a certain amount of recirculated cooling fluid (i.e. cooling fluid which does not directly reach into the cylinder head for further cooling) can be replaced by fresh cooling fluid, in order to also make it possible to uniformly cool the cylinder head with a uniform volume flow. The fact that the amount of cooling fluid recirculated to the first inlet can be compensated for by the compensation line means that the amount of cooling fluid recirculated is at least partly replaced by fresh cooling fluid.

Preferably, the liner cooling system may be arranged in a cylinder wall of the cylinder liner and the cover cooling system may be arranged in the cylinder head. The head cooling system is primarily used to cool the cylinder head and components disposed or mounted on the cylinder head, such as the outlet valve.

Here, the head cooling system may preferably be arranged in the cylinder head as follows: the cooling fluid may be supplied to the lid cooling system via a second cooling inlet and may be discharged from the lid cooling system via a second cooling outlet.

Similarly, the liner cooling system may preferably be arranged in the cylinder liner as follows: the cooling fluid may be supplied to the liner cooling system or the liner via a first cooling inlet and may be exhausted from the liner cooling system or the liner via a first cooling outlet.

Both the cover cooling system and the liner cooling system are preferably part of the cooling circuit of the cylinder arrangement.

It is particularly preferred that oil and/or water, in particular sea water and/or drinking water and/or fresh water, is used as cooling fluid. The cooling fluid is preferably moved through the cooling circuit by a circulation pump. The circulation pump may be, for example, a propeller pump or a centrifugal pump. Additional support pumps may be arranged on the cylinder arrangement to support the circulation of cooling fluid or to circulate other fluids.

Such a backing pump may be helpful, for example, if the cooling circuit is a closed circuit and is recooled with a recooling fluid (in particular, cryogenic cooling water). Here, for example, a heat exchanger can be used for recooling the cooling fluid with a recooling fluid, wherein both the cooling fluid and the recooling fluid are guided through the heat exchanger in the circuit (cooling circuit and recooling circuit), wherein the cooling fluid releases heat to the recooling fluid and is thus cooled. The sub-cooling circuit is preferably supplied with fresh or cold sub-cooling fluid, in particular seawater, and can be driven by a support pump. For example, the heat exchanger may be cooled using the counter-flow principle.

In addition to the cooling circuit belonging to the high-temperature system, the entire cooling system for a large engine preferably comprises a low-temperature system, with which the cooling fluid of the high-temperature system (cooling circuit) is recooled, and a further system, with which the recooled fluid of the low-temperature system is recooled. The cooling fluid belonging to the cooling circuit of the high temperature system is in direct thermal contact with the cylinders of the large engine. The cryogenic system is thermally coupled to the high temperature system via a heat exchanger such that the sub-cooling fluid of the cryogenic system can absorb heat from the cooling fluid of the high temperature system, thereby cooling it. The further system is thermally coupled to the cryogenic system via a heat exchanger, so that the heat carrier of the further system can absorb heat from the sub-cooling fluid of the cryogenic system and can thus cool it. Instead of a heat exchanger, a mixing system or one or more mixing devices can also be provided, provided that the coupling of the circuits is technically possible, for example in view of the pressure level and the compatibility of the cooling medium.

The cooling fluid of the high temperature system is preferably fresh water to which additives may be added. The sub-cooling fluid of the cryogenic system is preferably fresh water to which additives may be added. The heat carrier of the further system is preferably sea water, especially in case the large engine is a drive unit of a ship.

The cylinder arrangement may be designed such that the cooling fluid can be conveyed through the first cooling outlet directly or indirectly into the cylinder head. Indirectly means that the cooling fluid is led out of the cylinder liner and then into the cylinder head via a line.

Another aspect of the invention relates to a method for cooling a cylinder of a large engine comprising a cylinder arrangement according to the invention. In the method according to the invention, the recirculation amount of the cooling fluid is regulated via a mixing valve. For this purpose, the mixing valve is controlled and regulated as follows: the fresh cooling fluid and the recirculated cooling fluid are mixed in a predeterminable ratio to adjust the desired temperature. Of course, the control of the mixing valve can be automated and can be equipped with sensors, in particular temperature sensors, for example in the form of a control system. In this case, the temperature at a suitable point of the cooling circuit is preferably continuously recorded and compared with a predeterminable temperature reference value. The mixing valve is then influenced in the sense of being adjusted to the temperature reference value.

This has the following advantages: the cooling of the cylinder arrangement can be reliably adapted to the load of the engine.

Another aspect of the invention relates to a large engine comprising a cylinder arrangement according to the invention, wherein the amount of recirculation of the cooling fluid is regulated via a controllable mixing valve.

For example, the large engine may be designed as a longitudinally scavenged large engine.

In a preferred embodiment, the large engine is designed as a longitudinally scavenged two-stroke large diesel engine.

In particular, the large engine may also be designed as a dual-fuel large diesel engine, which may be operated in a liquid mode, wherein liquid fuel is introduced into the combustion chamber for combustion, and which may additionally be operated in a gas mode, wherein gas or low flash point liquid LFL is introduced as fuel into the combustion chamber. Alternatively, it is also possible that the dual fuel engine is also equipped with a hybrid mode that uses both fuels simultaneously.

For dual-fuel engines, this has the great advantage that the cooling of the cylinder arrangement can be reliably adapted to the load of the engine and the corresponding fuel. This is due to the high operating temperatures required for the cylinder liner in order to avoid acid formation due to condensation of water on the walls of the cylinder liner in diesel operations with heavy fuel oil, which typically contains sulphur, or another sulphur-containing fuel. In contrast, in gas operation, for example using natural gas as fuel, the lowest possible operating temperature of the cylinder liner is required.

If the operating temperature of the cylinder liner is too low in diesel operation, acids, particularly sulfurous and sulfuric acids, may be formed, which may damage the cylinder devices. On the other hand, acid formation is not generally a problem for gas operations, as there is generally no sulfur in gas or other highly flammable liquid fuels. However, in gas operation, excessive operating temperatures of the cylinder liner can lead to misfiring due to auto-ignition of the air-gas mixture. In gas operation, also for thermodynamic reasons, the aim is generally to cool the liner as much as possible.

Drawings

The invention is explained in more detail below in terms of equipment and process engineering with reference to the embodiments and the drawings. The figures show in schematic form:

FIG. 1 is a first embodiment of a cylinder device according to the present invention, and

fig. 2 is a second embodiment of the cylinder device according to the present invention.

Detailed Description