CN118030270A

CN118030270A - Large two-stroke turbocharged uniflow scavenged internal combustion engine and method of operating the same

Info

Publication number: CN118030270A
Application number: CN202311506609.1A
Authority: CN
Inventors: 卡斯滕·埃兰; 奥勒·斯凯特韦
Original assignee: Mannone Solutions Mannone Solutions Germany Branch
Current assignee: Mannone Solutions Mannone Solutions Germany Branch
Priority date: 2022-11-14
Filing date: 2023-11-13
Publication date: 2024-05-14
Also published as: JP2024071357A

Abstract

A large two-stroke turbocharged uniflow scavenged internal combustion engine and method of operating the same, the internal combustion engine configured to operate at jacket high water temperatures. An orifice in each of the fluid connections between the pressure vessel (74) or expansion tank (77) and the water-based cooling circuit (70) is provided for: in case of an unexpected boiling of water in the cooling jacket, cylinder head or exhaust valve due to stagnation in the water-based cooling circuit (70), the flow of water from the water-based cooling circuit (70) to the pressure vessel (74) or expansion tank (77) is throttled.

Description

Large two-stroke turbocharged uniflow scavenged internal combustion engine and method of operating the same

Technical Field

The present disclosure relates to large two-stroke internal combustion engines, particularly large two-stroke uniflow scavenged internal combustion engines with a crosshead operating on fuel (gaseous or liquid), configured to operate at jacket high water temperature (high jacket water temperature), and to a method of operating an engine of this type at jacket high water temperature.

Background

Turbocharged uniflow scavenged internal combustion engines with large two-stroke cross-heads are used, for example, for propulsion of large ocean-going vessels or as prime movers in power plants. Not only due to the large size of the internal combustion engines, these two-stroke diesel engines are also configured in a different way than any other internal combustion engine. The exhaust valves of these engines may weigh up to 400kg, the pistons may have a diameter of up to 100cm, and the maximum operating pressure in the combustion chamber is typically hundreds of bars. The forces involved in these high pressure levels and piston sizes are enormous.

Large two-stroke turbocharged internal combustion engines operate using the following fuels: liquid fuels (e.g., fuel oil, marine diesel, heavy oil, ethanol, dimethyl ether (DME)) or gaseous fuels (e.g., ammonia, methane, natural gas (LNG), petroleum gas (LPN), methanol, or ethane).

Engines operating on gaseous fuel may operate according to an otto cycle, where the gaseous fuel enters through a fuel valve centrally located along the length of the cylinder liner or in the cylinder head, i.e. these engines admit gaseous fuel during the stroke in which the piston begins to travel upwards (from BDC to TDC) before the exhaust valve closes, and compress a mixture of gaseous fuel and scavenging air in the combustion chamber and ignite the compressed mixture at or near TDC by a timed ignition device, such as a liquid fuel injection device.

Engines operating with liquid fuel and engines operating with gaseous fuel injected at high pressure, when the piston is near or at TDC, i.e. when the compression pressure in the combustion chamber is at or near its maximum, the engine injects gaseous or liquid fuel and therefore operates according to the diesel cycle, i.e. by compression ignition

In known two-stroke turbocharged internal combustion engines, the cylinder liner, cylinder head and exhaust valve are cooled by jacket water and maintained at a temperature of about 80 to 90 ℃, which limits the temperature of the cylinder liner, cylinder head, exhaust valve and indirectly limits the maximum absolute temperature in the combustion chamber simply increasing the temperature of the jacket water in the known engine is not possible because the known jacket water cooling system is not configured to handle such high temperatures and would involve the risk that the jacket water boils and thereby rapidly forces the jacket water out of the jacket water system and the jacket water cooling system is free of jacket water, thereby freeing the engine from forced cooling capacity.

JP2015132191 discloses a large two-stroke internal combustion engine.

Disclosure of Invention

It is an object of the present application to provide an engine and a method that overcome or at least reduce the above-mentioned problems.

The above and other objects are achieved by exemplary embodiments of the present application. Further embodiments are evident from the description and the drawing.

According to a first aspect, there is provided a large two-stroke turbocharged uniflow scavenged internal combustion engine having a crosshead, the engine comprising:

a plurality of combustion chambers, each combustion chamber being bounded by a cylinder liner, a piston configured to reciprocate in the cylinder liner,

A scavenging port arranged in each cylinder liner for admitting scavenging gas into the combustion chamber,

At least one cooling passage, the at least one cooling passage being located in the cylinder head,

An annular cooling chamber surrounding a portion of each cylinder liner,

An exhaust outlet arranged in each cylinder head and controlled by an exhaust valve,

The plurality of combustion chambers are connected to the scavenging gas receiver via scavenging ports and to the exhaust gas receiver via exhaust outlets,

An exhaust system comprising a turbine of a turbocharger system driven by an exhaust gas flow,

An air intake system including a compressor of the turbocharger system, the compressor configured to supply pressurized scavenging air to the scavenging gas receiver,

A main cooling circuit comprising at least one main circulation pump configured for circulating water in the main cooling circuit, at least one cooling channel in the cylinder head being part of the main cooling circuit, preferably an annular cooling chamber of the plurality of combustion chambers also being part of the main cooling circuit,

The engine comprises a pressure vessel or expansion tank connected to the main cooling circuit by a fluid connection for regulating the pressure of the water in the main cooling circuit and for allowing expansion and contraction of the water in the main cooling circuit,

The engine is characterized in that the fluid connection is formed by one or more pipes, each pipe comprising an orifice for throttling the flow of water from the main cooling circuit to the pressure vessel or expansion tank.

By providing an orifice in each of the fluid connections between the pressure vessel or expansion tank and the main cooling circuit, if water in the cooling chamber inadvertently boils due to stagnation in the main cooling circuit, water flow from the main cooling circuit to the pressure vessel or expansion tank is throttled. This throttling effect will slow down the draining of water from the main cooling circuit towards the pressure vessel or expansion tank, enough to reduce the temperature in the cooling chamber by passive cooling (assuming that the engine load is reduced or the engine stops in case of an unintentional stagnation of water in the main cooling circuit), thereby avoiding the water in the main cooling circuit being emptied and thereby allowing a quick restart of normal engine operation when the circulation capacity in the main cooling circuit is re-established.

In a possible embodiment of the first aspect, the orifice reduces the cross-sectional area available for flow by at least 49 times (by at least afactor fifty, i.e. by at least one fifth of the original value) relative to the one or more pipes forming the fluid connection, preferably the orifice reduces the cross-sectional area available for flow by at least 99 times (by at least one hundredth of the original value), most preferably the orifice reduces the cross-sectional area available for flow by at least 149 times (by at least one fiftieth of the original value).

In a possible implementation of the first aspect, the orifice reduces the cross-sectional area available for flow by a factor of between 74 and 249 (by a factor 75to 250 to between seventy-fifth and two hundred and fifty times the original value).

In a possible embodiment of the first aspect, the one or more pipes have a substantially constant inner diameter of between 35 and 80 millimeters, and wherein the at least one orifice has a minimum diameter of between 3 and 5 millimeters.

In a possible embodiment of the first aspect, the engine comprises a first check valve in the fluid connection, preferably in a supply conduit fluidly connecting the pressure vessel or the expansion tank to the deaerator, the first check valve being in parallel with one of the at least one orifice for allowing water to flow from the pressure vessel or the expansion tank to the main cooling circuit, preferably in parallel with one of the at least one orifice for allowing water to flow from the pressure vessel or the expansion tank to the main cooling circuit when the water in the cooling circuit contracts.

In a possible embodiment of the first aspect, the engine comprises a pressure setting valve in the fluid connection, preferably in a supply conduit fluidly connecting the pressure vessel or the expansion tank to the deaerator, the pressure setting valve being in parallel with one of the at least one orifice for allowing water to flow from the main cooling circuit to the pressure vessel or the expansion tank when the pressure of the water in the main cooling circuit rises above a threshold value, preferably in parallel with one of the at least one orifice for allowing water to flow from the main cooling circuit to the pressure vessel or the expansion tank when the pressure of the water in the main cooling circuit rises above a threshold value due to expansion of the water in the main cooling circuit.

In a possible implementation of the first aspect, the engine comprises a first control valve in the fluid connection, preferably in a supply conduit fluidly connecting the pressure vessel or the expansion tank to the deaerator, the first control valve being in parallel with one of the at least one orifice, preferably in parallel with one of the at least one orifice, for initial filling of the cooling circuit with water.

In one possible implementation manner of the first aspect, the engine includes:

An engine cooling water inlet and an engine cooling water outlet,

-A circulation conduit extending from the engine cooling water outlet to the engine cooling water inlet, and

A deaerator arranged in the circulation conduit and connected to the pressure vessel or the expansion tank by a supply conduit comprising an orifice and a first venting conduit comprising an orifice, and

Preferably, the engine comprises a second ventilation duct connecting the engine water outlet to the pressure vessel or expansion tank and comprising an orifice.

In a possible implementation of the first aspect, an orifice is provided in the circulation conduit at a position upstream of the deaerator, and a second control valve is provided in parallel with the orifice.

In a possible implementation of the first aspect, the at least one main circulation pump is arranged upstream of the deaerator.

In a possible implementation of the first aspect, the engine comprises a cooler for cooling water in the main cooling circuit, preferably the cooler is arranged in parallel with a cooler restriction arranged in the circulation conduit, and preferably the cooler is connected to the circulation circuit by a third control valve, preferably the third control valve is controlled by the controller.

In one possible implementation manner of the first aspect, the engine includes:

A controller receiving a first signal indicative of the temperature of the water in the cooling circuit, preferably the controller receiving a first signal indicative of the temperature of the water in the cooling circuit near the point where the water leaves the engine and enters the circulation duct,

The controller is configured to:

the temperature of the water in the main cooling circuit is controlled to at least 100 ℃, preferably to a temperature between 120 ℃ and 130 ℃.

In a possible implementation of the first aspect, the engine comprises a cooler controlled by the controller and configured to apply a selective amount of cooling to the water in the main cooling circuit under control of the controller for adjusting the amount of cooling applied to the water in the main cooling circuit to control the temperature of the water in the main cooling circuit to at least 100 ℃, preferably to a temperature between 120 ℃ and 130 ℃.

In a possible implementation of the first aspect, the engine is configured to operate at an engine load range between a minimum engine load and a maximum engine load, and wherein the controller is configured to: at least for the maximum engine load, and preferably for the entire engine load range between the minimum and maximum engine load, the temperature of the water in the main cooling circuit is controlled to a temperature above 100 c,

Preferably, the controller is configured to: the temperature in the main cooling circuit near the point where the water leaves the engine and enters the main circulation conduit is controlled to a temperature above 100 ℃ at least for the maximum engine load, and preferably for the entire engine load range between the minimum and maximum engine loads.

In a possible implementation of the first aspect, the engine is configured to operate at a pressure of at least 3 bar in the main cooling circuit.

In a possible implementation of the first aspect, the secondary cooling circuit is connected to a pressure vessel or expansion tank for regulating the pressure of the water in the primary cooling circuit and for allowing the water in the primary cooling circuit to expand and contract.

In a possible implementation of the first aspect, the main cooling circuit comprises a first part located inside the engine and a second part located outside the engine, the first part extending from the engine inlet towards the engine outlet, the first part comprising the cooling chamber, and preferably the first part comprising at least one passage in the cylinder head, and preferably the first part comprising at least one passage and/or chamber located in the housing of the exhaust valve.

In a possible implementation of the first aspect, the second part comprises a circulation line comprising at least one main circulation pump, a deaerator located upstream of the at least one main circulation pump, preferably the circulation line comprises a cooling device located upstream of the deaerator.

In one possible implementation of the first aspect, the engine includes an annular water jacket surrounding at least a portion of the cylinder liner and defining an annular cooling chamber with a radially outer side of the cylinder liner.

According to a second aspect there is provided a large two-stroke turbocharged uniflow scavenged internal combustion engine having a crosshead, the engine comprising:

At least one cooling passage located in the cylinder head;

A scavenging port arranged in each cylinder liner for admitting scavenging gas into at least one combustion chamber,

An annular cooling chamber surrounding a portion of each cylinder liner,

A secondary cooling circuit comprising a secondary circulation pump configured for circulating water in the secondary cooling circuit, at least one cooling passage in the cylinder head (22) being part of the secondary cooling circuit, preferably an annular cooling chamber of the plurality of combustion chambers also being part of the secondary cooling circuit,

The secondary cooling circuit is fluidly connected to the primary cooling circuit by a valve system for mixing water from the primary cooling circuit into water in the secondary cooling circuit,

The main cooling circuit comprises at least one main circulation pump for circulating water in the main cooling circuit,

A controller that receives a first signal representative of the temperature of the water in the secondary loop and a second signal representative of the temperature of the water in the primary cooling loop,

The controller is configured to control the temperature of the water in the primary cooling circuit to a temperature below 95 ℃ and the temperature of the water in the secondary cooling circuit to a temperature above 100 ℃, preferably the controller is configured to control the temperature of the water in the secondary cooling circuit to a temperature between 120 ℃ and 140 ℃, preferably the controller is configured to: the amount of water mixed into the water of the secondary cooling circuit from the water of the primary cooling circuit is regulated by a control valve system so that the temperature of the water in the primary cooling circuit is controlled to a temperature below 95 ℃ and the temperature of the water in the secondary cooling circuit is controlled to a temperature above 100 ℃.

By providing a secondary cooling system comprising an annular cooling chamber for the cylinders, and by operating the secondary cooling system at a temperature above 100 ℃, the fuel efficiency of the engine may be increased as described above with reference to the carnot theorem, while the main cooling system may be constructed in the same or similar manner as the main cooling system of the prior art, which typically operates at a temperature between 80 ℃ and 90 ℃. Thus, only the secondary cooling system and related components need be adapted to operate at higher temperatures.

In a possible implementation of the second aspect, the engine is configured to operate at an engine load range between a minimum engine load and a maximum engine load, and wherein the controller is configured to: the temperature of the water in the secondary cooling circuit is controlled to a temperature above 100 ℃ at least for the maximum engine load, and preferably for the engine load between the medium engine load and the maximum engine load, and more preferably for the engine load between the minimum engine load and the maximum engine load.

In a possible embodiment of the second aspect, the valve system comprises a fourth control valve, preferably a three-way control valve controlled by the controller, the fourth control valve being arranged in the primary cooling circuit and fluidly connected to the secondary cooling circuit via a return conduit, and the fourth control valve being configured to split a controllable amount of water flow from the secondary cooling circuit via the return conduit.

In a possible embodiment of the second aspect, the engine comprises a feed conduit connecting the secondary cooling circuit to the primary cooling circuit, preferably upstream of the fourth control valve.

In a possible embodiment of the second aspect, the valve system comprises a second check valve arranged in the secondary cooling circuit, preferably between the position where the return line and the secondary cooling circuit are connected and the position where the feed line and the secondary cooling circuit are connected.

In a possible implementation of the second aspect, the engine comprises a cooler for cooling water in the secondary cooling circuit.

In a possible embodiment of the second aspect, the engine comprises a deaerator arranged in the primary cooling circuit conduit and connected to the pressure vessel or expansion tank for regulating the pressure of the water in the primary cooling circuit conduit and the secondary cooling circuit and for allowing expansion and contraction of the water in the primary cooling circuit conduit and the secondary cooling circuit, preferably the pressure vessel or expansion tank is configured to maintain a pressure sufficient to prevent boiling of the water in the secondary cooling circuit due to the temperature of the water reaching 140 ℃, preferably the pressure vessel or expansion tank is configured to maintain a pressure sufficient to prevent boiling of the water in the secondary cooling circuit due to the temperature of the water reaching 130 ℃.

According to a third aspect, there is provided a method of operating a large two-stroke turbocharged uniflow scavenged internal combustion engine having a crosshead, the engine comprising:

An annular cooling chamber surrounding a portion of each cylinder liner,

A secondary cooling circuit comprising a secondary circulation pump configured for circulating water in the secondary cooling circuit, at least one cooling passage in the cylinder head being part of the secondary cooling circuit, preferably the cooling chambers of the plurality of combustion chambers also being part of the secondary cooling circuit,

The method comprises the following steps: the temperature of the water in the secondary loop is sensed,

The temperature of the water in the main cooling circuit is sensed,

Controlling the temperature of the water in the main cooling circuit to a temperature below 95 ℃, and

The temperature of the water in the secondary cooling circuit is controlled to a temperature above 100 ℃, preferably to a temperature between 120 ℃ and 140 ℃.

In one possible implementation of the third aspect, the engine is configured to operate at an engine load range between a minimum engine load and a maximum engine load, the method comprising: at least for a maximum engine load, and preferably for an engine load between a medium engine load and a maximum engine load, and more preferably for an engine load between a minimum engine load and a maximum engine load, the temperature of the water in the secondary loop is controlled to a temperature above 100 ℃, preferably the method comprises: the temperature of the water in the secondary loop is controlled to a temperature between 120 ℃ and 140 ℃ at least for the maximum engine load, and preferably for the engine load between medium and maximum engine load, and more preferably for the engine load between the minimum and maximum engine load.

In a possible implementation manner of the third aspect, controlling the temperature of the water in the secondary cooling circuit includes: by controlling the valve system, the amount of water from the primary cooling circuit that is mixed into the secondary cooling circuit is regulated.

In a possible implementation of the third aspect, the method comprises maintaining a pressure of at least 5 bar in the primary cooling circuit and the secondary cooling circuit.

These and other aspects will be apparent from the embodiments described below.

Drawings

In the following detailed description of the present disclosure, aspects, embodiments and implementations will be described in more detail with reference to example embodiments shown in the drawings, in which:

figure 1 is an elevation view of a large two-stroke diesel engine,

Figure 2 is another angular elevation of the large two-stroke engine of figure 1,

Figure 3 is a schematic view of a large two-stroke engine according to figures 1 and 2,

Figure 4 is a schematic view of a first embodiment of the engine of figures 1 to 3,

FIG. 5 is a schematic diagram of a second embodiment of the engine of FIGS. 1-3, an

Fig. 6 is a schematic diagram of a third embodiment of the engine of fig. 1-3.

Detailed Description

In the following detailed description, an internal combustion engine will be described with reference to a large two-stroke, low-speed turbocharged cross-head internal combustion engine in an exemplary embodiment. Fig. 1,2 and 3 show an embodiment of a large low-speed turbocharged two-stroke diesel engine with a crankshaft 8 and a cross-head (linkage) 9. Fig. 1 and 2 are elevation views from different angles. FIG. 3 is a schematic diagram of an embodiment of the large low speed turbocharged two-stroke diesel engine of FIGS. 1 and 2, wherein the diesel engine has its intake and exhaust systems. In this embodiment, the engine has six in-line cylinders. However, a large low-speed turbocharged two-stroke internal combustion engine may have between four and fourteen in-line cylinders, with the cylinder liners carried by the engine frame 11. The engine may for example be used as a main engine in a ship or as a stationary engine for operating a generator in a power plant. The total output of the engine may be, for example, in the range of 1,000kw to 110,000 kw.

In this exemplary embodiment, the engine is a two-stroke uniflow scavenged engine having scavenge ports 18 located in the lower region of the cylinder liner 1 and a central exhaust valve 4 located in the cylinder head 22 at the top of the cylinder liner 1. When the piston 10 is located below the scavenging port 18, scavenging gas (SCAVENGE GAS) passes from the scavenging gas receiver 2 through the scavenging port 18 of each cylinder liner 1.

In the case of an engine operating as a premix engine (Otto principle (otto principle)), gaseous fuel (e.g., methanol, petroleum gas or LPG, methane, natural gas LNG or ethane) enters from the gaseous fuel intake valve 50 'under the control of the electronic controller 100 when the piston 10 is in its upward motion (from BDC to TDC) and before the piston 10 passes the fuel valve 50' (gas intake valve). When the piston 10 is at or near TDC, a gaseous or liquid fuel (e.g., fuel oil) is injected into the combustion chamber fuel valve 50 at a high pressure (preferably 300 bar or higher). The fuel gas is introduced at a relatively low pressure below 30 bar, preferably below 25 bar, more preferably below 20 bar, and is supplied by the gaseous fuel supply system 30'. An electric current containing fuel for injection through the fuel valve 50 is supplied by the fuel system 30. The high pressure may be generated by the fuel system 30 (common rail) or in the fuel valve 50. The fuel inlet valve 50' is preferably evenly distributed around the outer circumference of the cylinder liner and is placed in a central region of the length of the cylinder liner 1. The entry of gaseous fuel occurs when the compression pressure is relatively low, i.e., much lower than when the piston reaches TDC (top dead center), thus allowing entry at a relatively low pressure.

When the engine is operated as a compression ignition engine (diesel principle), no gas enters the valve 50' and fuel (gaseous or liquid) is injected through the fuel valve 50 at high pressure when the piston 10 is at or near TDC.

The piston 10 in the cylinder liner 1 compresses a charge of gaseous fuel and a scavenging gas (or operates with fuel injection only at TDC to compress the scavenging gas) and at or near TDC, the fuel valve 50 is preferably arranged in the cylinder head 22 by injecting fuel at high pressure from the fuel valve 50 or by compression with liquid fuel injected only at or near TDC. Combustion then occurs and exhaust gas (exhaustgas) is produced.

When the exhaust valve 4 is open, the combustion gases flow through the combustion gas conduit associated with the cylinder 1 into the combustion/exhaust gas receiver 3 and onward through the first exhaust conduit 19, which first exhaust conduit 19 comprises a selective catalytic reactor 33 for reducing nitrogen oxides (NOx) in the exhaust gases.

The turbine 6 drives the compressor 7 by means of a shaft, the compressor 7 being supplied with fresh air via an air inlet 12. The compressor 7 delivers pressurized scavenging air to a scavenging air conduit 13 leading to the scavenging gas receiver 2. The scavenging air in the conduit 13 is passed through an intercooler 14 for cooling the scavenging air.

An exhaust gas recirculation conduit 35 is connected to the scavenge air conduit 13, either upstream (shown) or downstream (not shown) of the intercooler 14. At this location, the recirculated exhaust gas mixes with the scavenging air to form the scavenging gas flowing towards the scavenging gas receiver 2. The controller 100 (electronic control unit) is configured to adjust a ratio between the scavenging air and the exhaust gas in the scavenging gas, as will be described in more detail below.

When the compressor 7 of the turbocharger 5 does not deliver sufficient pressure for the scavenging gas receiver 2, i.e. at low or partial load of the engine, the cooled scavenging air or gas passes the auxiliary blowers 16 driven by the electric motor 17, the auxiliary blowers 16 pressurize the scavenging flow. At higher engine loads, the compressor 7 of the turbocharger delivers sufficient compressed scavenging air and then bypasses the auxiliary blowers 16 via the check valves 15. Notably, the test procedure may include more than one turbocharger 5, thereby forming a turbocharger system.

The controller 100 itself may comprise several interconnected electronic units including a processor and other hardware for performing the functions of the controller, the controller 100 typically being under control of the operation of the engine and controlling the following: such as the intake of gaseous fuel (quantity and timing), the injection of liquid fuel (quantity and timing), and the opening and closing of the exhaust valve 4 (timing and lift ranges), the recirculated exhaust gas ratio, and the operation of various coolers, pumps, and other devices. To this end, the controller 100 receives various signals from the sensors, which inform the controller 100 of the following information: the operating conditions of the engine (engine load, engine speed, blower speed, scavenging gas temperature, elevated gas temperature at various locations, exhaust gas temperature at various locations), pressure in the scavenging system, pressure in the combustion chamber, pressure in the exhaust system and pressure in the exhaust gas recirculation system, if any. Preferably, the engine includes a variable timing exhaust valve actuation system, allowing independent control of exhaust valve timing for each compression chamber. The controller 100 is connected via signal lines or wireless connectors to the fuel valve 50, the liquid fuel inlet valve 50', the exhaust valve actuator, an angular position sensor that detects the angle of the crankshaft and generates a signal representative of the position of the crankshaft, and a pressure sensor, preferably in the cylinder head 22 or alternatively in the cylinder liner 1, to generate a signal representative of the pressure in the combustion chamber.

The cylinder liner 1 can be manufactured in different sizes, depending on the engine size, the cylinder bore typically being in the range of 250mm to 1000mm, with a corresponding typical length in the range of 1000mm to 4500 mm.

The cylinder liners 1 are mounted in a cylinder frame 23, a cylinder head 22 is placed on top of each cylinder liner 1, with an airtight joint between the cylinder liner 1 and the cylinder head 22. At least one cooling passage is provided within the cylinder head 22 for cooling the cylinder heads 22, with at least one passage of each cylinder head 22 being fluidly connected to a water-based cooling system 60, 70, the water-based cooling system 60, 70 being described in detail below. The piston 10 is arranged to reciprocate between a Bottom Dead Center (BDC) and a Top Dead Center (TDC). These two extreme positions of the piston 10 are separated by a 180 degree revolution of the crankshaft 8. The cylinder liner 1 is provided with a plurality of circumferentially distributed cylinder lubrication holes, which are connected to cylinder lubrication lines that provide a supply of cylinder lubrication oil when the piston 10 passes through the cylinder lubrication holes 25, and then piston rings (not shown) in the piston 10 distribute the cylinder lubrication oil onto the working surface (inner surface) of the cylinder liner 1. The cylinder liner is provided with a jacket (not shown) and jacket cooling water circulates in the space between the jacket and the cylinder liner.

Liquid fuel valves 50 (typically having more than one liquid fuel valve per cylinder, preferably three or four liquid fuel valves) are mounted in the cylinder head 22 and are connected to the pressurized fuel source 30. The liquid fuel valves 50 are preferably arranged around the exhaust valves 4, in particular around the central outlet (opening) of the cylinder head 22, and are evenly distributed in the circumferential direction. The central profile is controlled by the exhaust valve 4. The timing and quantity of the fuel injection is developed to be controlled by the controller 100. The fuel valve 50 is used only to inject a small amount of ignition liquid (pilot) when the engine is operating in a premix mode. If the engine is operating in compression ignition mode, the amount of liquid fuel required to operate the engine at the actual engine load is injected through the liquid fuel valve 50. The cylinder head 22 may be provided with a prechamber (not shown) and the top of the liquid fuel valve 50, typically the top of a nozzle provided with one or more nozzle holes, is arranged such that a pilot oil (ignition liquid) is injected and atomized into the prechamber to trigger ignition. The pre-chamber helps to ensure reliable ignition.

A fuel inlet valve 50 'is mounted within the cylinder liner 1 (or in the cylinder head 22), the nozzle of the fuel inlet valve is substantially flush with the inner surface of the cylinder liner 1, and the rear end of the fuel valve 50' protrudes from the outer wall of the cylinder liner 1. Typically, one or two fuel valves are provided in each cylinder liner 1, but possibly up to three or four fuel valves 50', the fuel valves 50' being circumferentially distributed (preferably evenly circumferentially) around the cylinder liner 1. In one embodiment, the fuel inlet valve 50' is disposed generally midway along the length of the cylinder liner 1. The fuel inlet valve 50' is connected to a pressurized source of gaseous fuel 30' (e.g., methanol, LPG, LNG, ethane, or ammonia), i.e., the fuel is in the gas phase when it is delivered to the fuel inlet valve 50 '. Since the gaseous fuel is introduced during the stroke of the piston 10 from BDC to TDC, the pressure of the gaseous fuel source need only be higher than that present in the cylinder liner 1, and a pressure typically less than 20 bar is sufficient for the gaseous fuel to be delivered to the fuel inlet valve 50'. The fuel inlet valve 50' is connected to the controller 100, and the controller 100 determines the timing of the opening and closing of the fuel inlet valve 50' and the duration of the opening of the fuel inlet valve 50 '.

In one embodiment, the liquid fuel used for ignition is fuel oil, marine diesel, heavy fuel oil, ethanol or dimethyl ether (DME).

The gaseous operating mode may be one of a plurality of operating modes of the engine. Other modes may include a liquid fuel mode of operation in which all fuel required for engine operation is provided in liquid form through liquid fuel valve 50. In the gaseous fuel operating mode, the engine is operated with gaseous fuel, which enters as a main fuel at a relatively low pressure during the stroke of the piston from bottom dead center to top dead center, i.e. providing a large part of the energy supplied to the engine, whereas in contrast the liquid fuel constitutes a relatively small amount of fuel, which only contributes relatively little to the energy supplied to the engine, the purpose of the liquid fuel being to time ignition, i.e. the liquid fuel is used as ignition liquid.

Thus, the engine of the present embodiment may be a dual fuel engine, i.e. the engine has a mode of operation solely on liquid fuel and a mode of operation almost solely on gaseous fuel.

In this embodiment, the engine is shown as a premixed engine operating according to the otto principle. However, it should be appreciated that the engine may also be a compression ignition engine (operating according to the diesel engine principle) in which fuel (gaseous or liquid) is injected at high pressure when the piston 10 is at or near TDC.

The engine operates by: the combustion chamber is supplied with fuel (liquid fuel and/or gaseous fuel) and the fuel is combusted in the combustion chamber, thereby producing an exhaust stream. In an embodiment not shown, a first portion of the exhaust gas stream (or combustion gas stream in embodiments in which the recirculated gas is directly from the combustion chamber) is recirculated, and another (second) portion of the exhaust gas stream is discharged as exhaust gas.

Downstream of the turbine 6 of the turbocharger 5, the exhaust gas enters a second exhaust gas duct 28, the second exhaust gas duct 28 guiding the exhaust gas to a boiler 20 (also referred to as an economizer), the boiler 20 typically being configured to generate steam. Steam is used, for example, on a ship equipped with an engine for various purposes. The second exhaust duct 28 continues downstream of the boiler 20 and is open to the atmosphere.

The cylinder liner 1 is provided with a jacket 21 defining an annular cooling chamber 23. The annular cooling chamber 23 is preferably arranged in the upper part of the cylinder liner 1 where the thermal load is highest. The annular cooling chamber 23 is fluidly connected to a water-based cooling system 60, 70, which will be described in more detail below. Typically, the cylinder head 22 and the accommodation for the exhaust valve 4 are provided with channels and chambers for receiving cooling water from a water-based cooling system.

Fig. 4 shows a first embodiment of an engine with a water-based cooling system shown schematically. In this embodiment, the water-based cooling system includes a primary cooling circuit 70 and a secondary cooling circuit 60. The main cooling circuit 70 includes a main circulation conduit 73, the main circulation conduit 73 being filled with water during engine operation. The main circulation pipe 73 includes a main circulation pump 72, and the main circulation pump 72 serves to circulate water in the main circulation loop 73. Two or more main circulation pumps 72 are provided to provide redundancy. A check valve is provided downstream of each of the main circulation pumps 72. A first temperature sensor 75 is provided upstream of the check valve. A deaerator (deaeration vessel) 78 is arranged upstream of the main circulation pump 72 for removing air, gas, vapor accumulated in the water and removing the retained bubbles. Deaerator 78 is connected to pressure vessel 74 or expansion tank 77 via supply and exhaust lines. The function of the pressure vessel 74 or expansion tank 77 is to store water, provide pressure in the water-based cooling system, and allow the water in the water-based cooling system to expand and contract as the temperature of the water changes.

Typically, a cooling device is provided upstream of the deaerator 78, which cooling device comprises a cooler 79, for example a heat exchanger, which exchanges heat with sea water or another cooling medium if the engine is mounted on a ship. The cooler 79 is fluidly connected to the main circulation duct 73 by a third control valve 71, for example a three-way control valve, and arranged in parallel with an orifice (not shown in fig. 4, shown as orifice 83 in fig. 5 and 6), the restriction of flow by the third control valve being substantially equal to the restriction of flow of the cooler 79, so that changing the size of the portion of the water flow through the cooler 79 with respect to the portion of the flow bypassing the cooler 79 does not significantly affect the flow conditions, i.e. does not significantly affect the resistance experienced by the main circulation pump 72. The third control valve 71 is under the control of the controller 100 and adjusts the ratio between the water passing through the cooler 79 and the water bypassing the cooler 79, thereby adjusting the cooling capacity to control the temperature of the water in the main cooling circuit 70. To this end, the controller 100 receives a signal representing the temperature of the cooling water from the first temperature sensor 75, and the controller 100 is configured to adjust the temperature of the water in the main cooling circuit 70 to a temperature between, for example, 80 ℃ and 90 ℃, preferably to adjust the temperature of the water in the main cooling circuit 70 to less than 95 ℃, wherein the target temperature is 85 ℃. The main circulation duct 73 is coupled to the engine via the engine water inlet 41 and the engine water outlet 42, for example by a flange.

The fourth control valve 56 is for example a three-way valve, the fourth control valve 56 being arranged in the main circulation circuit 73 downstream of the main circulation pump 72 and its associated check valve, preferably in a portion of the main circulation conduit 73 extending between the engine inlet 41 and the transmitter outlet 42. The fourth control valve 56 is connected to a return line 82, which return line 82 is connected to the secondary loop line 63 of the secondary loop 60. The secondary circulation pipe 63 includes a secondary check valve 57 and the return pipe 82 is connected to the secondary circulation pipe 60 located upstream of the secondary check valve 57. The supply pipe 81 is connected to the main circulation pipe 73 upstream of the fourth control valve 56, and is connected to the sub circulation pipe 63 at a position downstream of the sub check valve 57.

The pressure vessel 74, expansion tank 77 are together with the main circulation pump 72 configured for maintaining a pressure sufficient to prevent boiling of the water in the main cooling circuit 60 and the secondary cooling circuit 70 when the temperature of the water increases to reach 140 ℃, preferably to prevent boiling of the water in the main cooling circuit 60 and the secondary cooling circuit 70 when the temperature of the water increases to reach 130 ℃, i.e. the pressure vessel 74, expansion tank 77 together with the main circulation pump 72 are configured for maintaining a pressure in the water in the main cooling circuit to at least 3 bar (barg), preferably at least 4 bar, most preferably at least 5 bar.

The fourth control valve 56 is under the control of the controller 100 and adjusts the ratio between the water supplied to the secondary circulation pipe 63 and the water bypassing the secondary circulation pipe 63, thereby adjusting the amount of water in the primary circulation loop 73 mixed with the water of the secondary circulation loop 63 for adjusting the temperature of the water in the secondary cooling loop 60. To this end, the controller 100 receives a signal from the second temperature sensor 65 representing the temperature of the cooling water in the secondary cooling circuit 63, and the controller 100 is configured to adjust the temperature of the water in the secondary cooling circuit 60 to a temperature, for example above 100 ℃, preferably to a temperature between 120 ℃ and 140 ℃. The secondary circulation pump 62 ensures circulation of water in the circulation loop 63. The arrangement of the sub-circulation pump 62 is bypassed so that the sub-circulation pump 62 can be bypassed if desired.

The fourth control valve 56 is preferably a three-way control valve controlled by the controller 100, the fourth control valve 56 being arranged in the primary cooling circuit 70 and being fluidly connected to the secondary cooling circuit 60 via a supply conduit 82, and the fourth control valve 56 being configured to divert a controllable-sized water flow to the secondary cooling circuit 60 via the supply conduit 82, thereby diverting an equally sized water flow from the secondary cooling circuit 60 to the primary cooling circuit 70.

The cooling circuit 60 passes through the annular cooling chamber 23 of all cylinder liners 1 and through the cylinder head 22 and optionally also through the accommodation of the exhaust valve 4, so that all cylinder liners 1, cylinder heads 22 and optionally the accommodation of the exhaust valve 4 are operated at an elevated temperature (with respect to known large two-stroke internal combustion engines operating at an elevated temperature such that the cooling water in the cooling chamber has a temperature between 80 ℃ and 90 ℃) in order to improve the fuel efficiency.

The rectangle shown in broken lines in fig. 4 represents all components considered to be part of an actual engine, while the remaining components are considered to be part of a water-based cooling system, i.e. part of an auxiliary system.

Fig. 5 shows a second embodiment of the engine. In this embodiment, the same or similar structures and features as those previously described or shown are denoted by the same reference numerals as previously used for the sake of simplicity. In this embodiment, the engine and its operation are largely the same as those of the foregoing embodiment, and therefore only the differences from the foregoing embodiment will be described in detail.

This embodiment comprises a main cooling circuit 70, which main cooling circuit 70 is connected to the engine via an engine water inlet 41 and an engine water outlet 42, a part of which cooling circuit extends through the engine, in particular through the cooling chamber 23, and optionally also through the cylinder head 22 and the accommodation of the exhaust valve 4 for cooling these components. In this embodiment, the expansion tank 77 is used to ensure static pressure and form a reservoir for allowing the water in the main cooling circuit 70 to expand and contract due to temperature fluctuations of the water in the main cooling circuit 70.

The expansion tank 77 is configured with the main circulation pump 72 for maintaining a pressure such that the pressure is sufficient to prevent boiling of the water in the main cooling circuit 70 at a temperature of up to 140 ℃, preferably to prevent boiling of the water in the main cooling circuit 70 at a temperature of up to 130 ℃, i.e. the expansion tank 77 is configured with the main circulation pump 72 for maintaining a pressure in the water in the main cooling circuit of at least 3 bar (barg), preferably at least 4 bar, most preferably at least 5 bar.

A supply conduit 89 is connected to the expansion tank 77, which supply conduit 89 is used for replenishing water again, and a vent 90 is used to allow air above the water surface in the expansion tank 77 to communicate with the atmosphere, thereby maintaining a constant pressure in the expansion tank 77. In one embodiment, a water level sensor is provided to monitor the water level in the expansion tank 77. Thus, during normal operation, the expansion tank 77 is always partially filled with water.

The cooler 79 and associated third control valve 71 and orifice 83 are disposed upstream of the deaerator, and the third control valve 71 operates under the control of the controller 100.

In this embodiment, three main circulation pumps 72 are shown, but it should be understood that the main cooling circuit may be operated with two or more circulation pumps to provide a sufficient level of redundancy. The deaeration vessel 78 is connected to the expansion tank 77 by a first ventilation conduit 85 for allowing air, gas or steam that has been removed from the water in the main cooling circuit 72 to escape to the atmosphere that is burned in the expansion tank 77. The degassing vessel 78 is also connected to the expansion vessel 77 by a supply conduit 84, the supply conduit 84 forming a main fluid connection for transferring water pressure and exchanging water volumes between the main circulation circuit 73 and the expansion tank 77. A second air passage 87 connects the engine water outlet 42 directly to the expansion tank 77. Thus, in this embodiment there are three pipes 84, 85, 87 connecting the expansion tank 77 to the main circulation loop 73. Each of these three ducts 84, 85, 87 is provided with an orifice 87, 88, 93 for throttling the water flow from the main circulation duct 73 to the expansion tank 77 in case of stagnation of the water in the main circulation duct 73, which would cause water to enter the part of the circulation duct 73 located in the engine, in particular into the cooling chamber 23 and through the cylinder head 22, and in particular when the engine has been operated at high or maximum load, making the cylinder liner 1 and the cylinder head 22 relatively hot. In this case, it is advantageous that the boiling water does not drain all the water from the main circulation pipe 73 into the expansion tank 77 and possibly from the expansion tank 77 to the atmosphere. This is accomplished by the throttling action of the orifices 78, 88, 93, which orifices 78, 88, 93 slow the flow of water to the expansion tank 77, thereby providing sufficient time for passive cooling of the cylinder liner 1 (and the receiving portions of the cylinder head 22 and exhaust valve) such that most or all of the water in the main circulation duct 73 remains in the main circuit duct 73. The tubing forming the supply conduit 84, the first ventilation conduit 85 and the second ventilation conduit 87 typically has a substantially constant inner diameter of between 35mm and 80mm, and wherein the orifice preferably has a minimum diameter of between 3mm and 5 mm. Preferably, the apertures 87, 88, 93 reduce the cross-sectional area available for flow by at least 49 times (by at least a factor fifty, to at least one fifth of the original value), preferably by at least 99 times (to at least one hundredth of the original value), most preferably by at least 149 times (to at least one hundred fifty percent of the original value) relative to the conduits 84, 85, 87.

In one embodiment, a first check valve 91 is disposed in the supply conduit 84 in parallel (parallel) with the orifice 93 to ensure that water from the expansion tank 77 fills the circulation conduit 73 quickly as the water contracts.

In one embodiment, a pressure set valve 92 is disposed in the supply conduit 84 and in parallel with the orifice 93 to allow water to flow from the main cooling conduit 73 toward the pressure vessel 74 or expansion tank 77 when the water pressure in the main cooling circuit 70 rises above a threshold value (the pressure threshold value is set by the pressure set valve opening pressure). Preferably, the water pressure in the main cooling circuit 70 increases above a threshold due to expansion of the water in the main cooling circuit 70.

In one embodiment, a first control valve 94 is disposed in the supply conduit 84 in parallel with the orifice 93 to effect initial filling of the cooling circuit 70 with water.

In one embodiment, the controller receives a first signal representative of the temperature of the water in the cooling circuit, preferably a signal representative of the temperature of the following water: the temperature of the water adjacent to where the water exits the engine and enters the main circulation conduit, and the controller 100 is configured to control the temperature of the water in the main cooling circuit 70 to at least 100 ℃, preferably to a temperature between 120 ℃ and 130 ℃. The cooler 79 is controlled by the controller 100 and is configured to apply a selective amount of cooling to the water in the main cooling circuit 70 under the control of the controller 100 to adjust the amount of cooling applied to the water in the main cooling circuit 70. Thereby controlling the temperature of the water in the main cooling circuit 70 to at least 100 ℃, preferably to a temperature between 120 ℃ and 130 ℃.

The engine is configured to operate at an engine load range between a minimum engine load and a maximum engine load (maximum sustained rating), and the controller 100 is configured to control the temperature of water in the main cooling circuit 70 at a location adjacent to: the water leaves the engine and enters the main circulation duct 73, controlling the temperature of the water in the main cooling circuit 70 to a temperature above 100 ℃ at least for the maximum engine load and preferably for the entire engine load range between the minimum and maximum engine load.

The embodiment of fig. 5 has been disclosed as using an expansion tank 77, but it should be understood that this embodiment would function equally with the pressure vessel 74. The embodiment of fig. 5 has been disclosed as using a single cooling circuit 70 (primary cooling circuit 70), but it should be understood that this embodiment would function equally using a combination of primary and secondary cooling circuits 70, 60 as disclosed with reference to fig. 4.

Fig. 6 shows a third embodiment of the engine. In this embodiment, the same or similar structures and features as those previously described or shown are denoted by the same reference numerals as previously used for the sake of simplicity. In this embodiment, the engine and its operation are largely the same as those of the foregoing embodiment, and therefore only the differences from the foregoing embodiment will be described in detail.

The third embodiment is substantially the same as the second embodiment except for the following: the pressure vessel 74 is used to contain pressure and accommodate expansion and contraction of the water in the main circulation pipe 73. Furthermore, the supply conduit 84 is not provided with an orifice 93, but rather an orifice 98 is provided in the main circulation conduit 73 downstream of the engine water outlet 42. The return valve between the main circulation pump 72 and the engine water inlet 41 prevents water from flowing from the engine inlet to the main circulation pump 72 when: in the event of a stagnation, for example, due to a malfunction of the circulation pump 72 or the lack of power to the electric motor for driving the circulation pump 72. Thus, in case of stagnation of water in the main circulation duct 73, for example, water in the annular cooling chamber 23 can only flow out through the engine water outlet 42. However, the orifice 98 throttles the flow from the annular cooling chamber 23 and the cylinder head 22 toward the pressure vessel 74. However, during normal operation, the orifice 98 should not limit the circulation of water in the main circulation duct 73. Thus, the second control valve 97 is optionally arranged in parallel with the orifice 98. The second control valve 97 is normally open and closes automatically, for example when the water in the main circulation pipe 73 stagnates. The second control valve may be optionally automatically closed in response to a lack of flow in the main circulation circuit 73 triggered by hydraulic or hydro-mechanical means, or alternatively by electronic means in response to a signal, for example in response to a signal indicating that the main circulation pump 72 is not running or another signal indicating that water in the main circulation line is stagnant.

The embodiment of fig. 6 has been disclosed as using a pressure vessel 74, but it should be understood that this embodiment will function equally with the expansion tank 77. The embodiment of fig. 6 has been disclosed as using a single cooling circuit 70 (primary cooling circuit 70), but it should be understood that this embodiment would function equally using a combination of primary and secondary cooling circuits 70, 60 as disclosed with reference to fig. 4.

Various aspects and implementations have been described in connection with various embodiments herein. The embodiments may be combined in various ways. Furthermore, other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed subject matter, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processor, controller or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. The reference signs used in the claims shall not be construed as limiting the scope of the claims.

Claims

1. A large two-stroke turbocharged uniflow scavenged internal combustion engine with a crosshead, the engine comprising:

a plurality of combustion chambers, each combustion chamber being delimited by a cylinder liner (1), a piston (10) configured to reciprocate in the cylinder liner (1), and a cylinder head (22),

A scavenging port (18), said scavenging port (18) being arranged in each cylinder liner (1) for admitting scavenging gas into said combustion chamber,

At least one cooling channel in the cylinder head (22),

An annular cooling chamber (23), said annular cooling chamber (23) surrounding a portion of each cylinder liner (1),

An exhaust gas outlet arranged in each cylinder head (22) and controlled by an exhaust valve (4),

A plurality of said combustion chambers being connected to a scavenging gas receiver (2) via said scavenging ports (18) and to an exhaust gas receiver (3) via said exhaust gas outlets,

An exhaust system comprising a turbine (6) of a turbocharger system (5) driven by an exhaust gas flow,

An air intake system comprising a compressor (7) of the turbocharger system (5), the compressor (7) being configured to supply pressurized scavenging air to the scavenging gas receiver (2),

-A main cooling circuit (70), the main cooling circuit (70) comprising at least one main circulation pump (72), the at least one main circulation pump (72) being configured for circulating water in the main cooling circuit (70), at least one cooling channel in the cylinder head (22) being part of the main cooling circuit (70), preferably the annular cooling chambers (23) of a plurality of the combustion chambers also being part of the main cooling circuit (70),

It is characterized in that the method comprises the steps of,

The engine comprises a pressure vessel (74) or an expansion tank (77), the pressure vessel (74) or expansion tank (77) being connected to the main cooling circuit (70) by a fluid connection (73, 84, 85, 87) for allowing contraction and expansion of water in the main cooling circuit (70), the fluid connection being formed by one or more pipes (73, 84, 85, 87), wherein each pipe comprises an orifice (87, 88, 93, 98) for throttling a flow of water from the main cooling circuit (70) towards the pressure vessel (74) or expansion tank (77).

2. The engine of claim 1, wherein the orifice (87, 88, 93, 98) reduces a cross-sectional area available for flow by at least forty-nine times, preferably the orifice (87, 88, 93, 98) reduces a cross-sectional area available for flow by at least ninety-nine times, most preferably the orifice (87, 88, 93, 98) reduces a cross-sectional area available for flow by at least one hundred forty-nine times, relative to the one or more conduits (73, 84, 85, 87) forming the fluid connection.

3. The engine of claim 2, wherein the one or more conduits (73, 84, 85, 87) have a substantially constant inner diameter of between 35 and 80 millimeters, and wherein at least one of the apertures (87, 88, 93, 98) has a minimum diameter of between 3 and 5 millimeters.

4. The engine according to any of the preceding claims, wherein the engine comprises a first check valve (91) in the fluid connection (73, 84, 85, 87), preferably in a supply conduit (84) fluidly connecting the pressure vessel (74) or expansion tank to a deaerator (78), the first check valve (91) being in parallel with one of the at least one orifice (87, 88, 93, 98) for allowing water to flow from the pressure vessel (74) or expansion tank (77) to the main cooling circuit (70), preferably the first check valve (91) being in parallel with one of the at least one orifice (87, 88, 93, 98) for allowing water to flow from the pressure vessel (74) or expansion tank (77) to the main cooling circuit (70) when water in the cooling circuit (70) contracts.

5. The engine according to any of the preceding claims, wherein the engine comprises a pressure setting valve (92), the pressure setting valve (92) being located in the fluid connection (73, 84, 85, 87), preferably in a supply conduit (84) fluidly connecting the pressure vessel (74) or expansion tank to a deaerator (78), the pressure setting valve (92) being in parallel with one of the at least one orifice (87, 88, 93, 98) for allowing water to flow from the main cooling circuit (70) to the pressure vessel (74) or expansion tank (77) when the pressure of the water in the main cooling circuit (70) increases above a threshold value, preferably the pressure setting valve (92) being in parallel with one of the at least one orifice (87, 88, 93, 98) for allowing water to flow from the main cooling circuit (70) to the expansion tank (77) when the pressure of the water in the main cooling circuit (70) increases above the threshold value due to the water in the main cooling circuit (70).

6. The engine according to any of the preceding claims, wherein the engine comprises a first control valve (94), the first control valve (94) being located in the fluid connection (73, 84, 85, 87), preferably the first control valve (94) being located in a supply conduit (84) fluidly connecting the pressure vessel (74) or expansion tank (77) to a deaerator (78), the first control valve (94) being connected in parallel with one of at least one of the orifices (87, 88, 93, 98), preferably the first control valve being connected in parallel with one of at least one of the orifices (87, 88, 93, 98) to achieve an initial filling of the cooling circuit (70) with water.

7. An engine according to any one of the preceding claims, wherein the engine comprises:

an engine cooling water inlet (41) and an engine cooling water outlet (42),

A main circulation pipe (73), the main circulation pipe (73) extending from the engine cooling water outlet (42) to the engine cooling water inlet (41), and

-A deaerator (87), said deaerator (87) being arranged in said main circulation conduit (73) and being connected to said pressure vessel (74) or expansion tank (77) by a supply conduit (84) comprising an orifice (93) and a first venting conduit (85) comprising an orifice (87), and preferably said engine comprises a second venting conduit (87) connecting an engine water outlet (42) to said pressure vessel (74) or expansion tank (77), said second venting conduit (87) comprising an orifice (88).

8. An engine according to claim 7, wherein an orifice (98) is provided in the main circulation duct (73) at a position upstream of the deaerator (87), and a second control valve (97) is provided in parallel with the orifice (98).

9. The engine according to claim 7 or 8, wherein the at least one main circulation pump (72) is arranged upstream of the deaerator (78).

10. The engine according to any one of claims 7 to 9, wherein the engine comprises a cooler (79) for cooling water in the main cooling circuit (70), preferably the cooler is arranged in parallel with a cooler limiter (83) arranged in the main circulation duct (73), and preferably the cooler (79) is connected to the main circulation duct (73) by a third control valve (71), preferably the third control valve (71) is controlled by a controller (100).

11. An engine according to any one of the preceding claims, wherein the engine comprises:

a controller (100) receiving a first signal indicative of the temperature of water in the main cooling circuit (70), preferably a first signal indicative of the temperature near the location where water leaves the engine and enters the main circulation duct (73),

The controller (100) is configured to:

The temperature of the water in the main cooling circuit (70) is controlled to at least 100 ℃, preferably the temperature of the water in the main cooling circuit (70) is controlled to a temperature between 120 ℃ and 130 ℃.

12. The engine of claim 11, wherein the engine comprises a cooler (79), the cooler (79) being controlled by the controller (100) and configured to apply a selective amount of cooling to water in the main cooling circuit (70) under control of the controller (100) for regulating the amount of cooling applied to water in the main cooling circuit (70),

Thereby controlling the temperature of the water in the main cooling circuit (70) to at least 100 ℃, preferably controlling the temperature of the water in the main cooling circuit (70) to a temperature between 120 ℃ and 130 ℃.

13. The engine of any of the preceding claims, wherein the engine is configured to operate at an engine load range between a minimum engine load and a maximum engine load, and wherein the controller (100) is configured to: controlling the temperature of the water in the main cooling circuit (70) to a temperature above 100 ℃ at least for the maximum engine load, and preferably for the entire engine load range between the minimum engine load and the maximum engine load,

Preferably, the controller (100) is configured to: the temperature in the main cooling circuit (70) near the point where water leaves the engine and enters the main circulation conduit (73) is controlled to a temperature above 100 ℃ at least for the maximum engine load, and preferably for the entire engine load range between the minimum engine load and the maximum engine load.

14. The engine according to any of the preceding claims, wherein the main cooling circuit (70) is connected to the pressure vessel (78) or an expansion tank (77) for allowing expansion and contraction of water in the main cooling circuit (70).

15. An engine according to any of the preceding claims, wherein the main cooling circuit (70) comprises a first part located inside the engine, which extends from an engine inlet (41) to an engine outlet (42), and a second part located outside the engine, which comprises the cooling chamber (23), and preferably at least one passage in the cylinder head (22), and preferably at least one passage and/or chamber in the housing of the exhaust valve (4).

16. The engine according to claim 15, wherein the second part comprises a main circulation pipe (73), the main circulation pipe (73) comprising the at least one main circulation pump (72), a deaerator (78) located upstream of the at least one main circulation pump (72), preferably the main circulation pipe (73) comprises cooling means (71, 79, 83) located upstream of the deaerator (78).

17. The engine according to any of the preceding claims, wherein the engine comprises an annular water jacket (21), the annular water jacket (21) surrounding at least a portion of the cylinder liner (1) and defining the annular cooling chamber (23) together with a radially outer side of the cylinder liner (1).

18. A large two-stroke turbocharged uniflow scavenged internal combustion engine having a crosshead, the engine comprising:

At least one cooling channel located in the cylinder head (22);

a scavenging port (18) arranged in each cylinder liner (1) for admitting scavenging gas into at least one of said combustion chambers,

-A secondary cooling circuit (60), said secondary cooling circuit (60) comprising a secondary circulation pump (62) configured for circulating water in said secondary cooling circuit (60), said at least one cooling channel in said cylinder head (22) being part of said secondary cooling circuit (60), preferably a plurality of cooling chambers (23) of said combustion chambers (1) being also part of said secondary cooling circuit (60),

The secondary cooling circuit (60) is fluidly connected to a primary cooling circuit (70) by a valve system (56, 57) for mixing water from the primary cooling circuit (70) into water in the secondary cooling circuit (60),

The primary cooling circuit (70) comprising at least one primary circulation pump (72), the at least one primary circulation pump (72) being adapted to circulate water in the primary cooling circuit (70), a controller (100), the controller (100) receiving a first signal representative of the temperature of the water in the secondary cooling circuit (60) and receiving a second signal representative of the temperature of the water in the primary cooling circuit (70),

The controller (100) is configured to: controlling the temperature of the water in the primary cooling circuit (70) to a temperature below 95 ℃ and the temperature of the water in the secondary cooling circuit (60) to a temperature above 100 ℃, preferably the controller (100) is configured to control the temperature of the water in the secondary cooling circuit (60) to a temperature between 120 ℃ and 140 ℃, preferably the controller (100) is configured to: by controlling the valve system (56, 57), the amount of water from the primary cooling circuit (70) that is mixed into the secondary cooling circuit (60) is regulated so as to control the temperature of the water in the primary cooling circuit (70) to a temperature below 95 ℃ and the temperature of the water in the secondary cooling circuit (60) to a temperature above 100 ℃, preferably the temperature of the water in the secondary cooling circuit (60) to a temperature between 120 ℃ and 140 ℃.

19. The engine of claim 18, wherein the engine is configured to operate at an engine load range between a minimum engine load and a maximum engine load, and wherein the controller (100) is configured to: the temperature of the water in the secondary cooling circuit (60) is controlled to a temperature above 100 ℃ at least for a maximum engine load, and preferably for an engine load between a medium engine load and a maximum engine load, and more preferably for an engine load between a minimum engine load and the maximum engine load.

20. The engine of claim 18 or 19, wherein the valve system (56, 57) comprises a fourth control valve (56), preferably the fourth control valve (56) is a three-way control valve controlled by the controller (100), the fourth control valve (56) being arranged in the primary cooling circuit (70) and being fluidly connected to the secondary cooling circuit (60) via a return conduit (82), and the fourth control valve (56) being configured to divert a controllable amount of water flow from the secondary cooling circuit (60) via the return conduit (82).

21. Engine according to claim 20, comprising a feed conduit (81), said feed conduit (81) connecting the secondary cooling circuit (60) to the primary cooling circuit (70), preferably said feed conduit (81) being located upstream of the fourth control valve (56).

22. An engine according to claim 20 or 21, wherein the valve system (56, 57) comprises a second check valve (57) arranged in the secondary cooling circuit (60), preferably between the position where the return conduit (82) and the secondary cooling circuit (60) are connected and the position where the feed conduit (81) and the secondary cooling circuit (60) are connected.

23. The engine of any of claims 18 to 22, wherein the engine comprises a cooler (79) for cooling water in the secondary cooling circuit (70).

24. The engine according to any one of claims 18 to 23, wherein the engine comprises a deaerator (87), the deaerator (87) being arranged in the main cooling circuit conduit (70) and connected to a pressure vessel (74) or an expansion tank (77) for regulating the pressure of the water in the main cooling circuit conduit (70) and the secondary cooling circuit (60) and for allowing expansion and contraction of the water in the main cooling circuit conduit (70) and the secondary cooling circuit (60), preferably the pressure vessel (74) or expansion tank (77) is configured to maintain a pressure sufficient to prevent boiling of the water in the secondary cooling circuit (60) due to the temperature of the water up to 140 ℃, preferably the pressure vessel (74) or expansion tank (77) is configured to maintain a pressure sufficient to prevent boiling of the water in the secondary cooling circuit (60) due to the temperature of the water up to 130 ℃.

25. A method of operating a large two-stroke turbocharged uniflow scavenged internal combustion engine having a crosshead, the engine comprising:

At least one cooling channel in the cylinder head (22),

A scavenging port (18), said scavenging port (18) being arranged in each cylinder liner (1) for admitting scavenging gas into at least one of said combustion chambers,

An annular cooling chamber (23) surrounding a portion of each cylinder liner (1),

An exhaust gas outlet which is arranged in each cylinder head (22) and is controlled by an exhaust valve (4),

-A secondary cooling circuit (60), the secondary cooling circuit (60) comprising a secondary circulation pump (62) configured for circulating water in the secondary cooling circuit (60), at least one cooling channel in the cylinder head (22) being part of the secondary cooling circuit (60), preferably a plurality of cooling chambers (23) of the combustion chambers (1) being part of the secondary cooling circuit (60) as well,

The main cooling circuit (70) comprises at least one main circulation pump (72), the at least one main circulation pump (72) being used for circulating cooling water in the main cooling circuit (70),

The method comprises the following steps: sensing the temperature of water in the secondary cooling circuit (60),

Sensing the temperature of water in the main cooling circuit (70),

Controlling the temperature of the water in the main cooling circuit (70) to a temperature below 95 ℃, and

The temperature of the water in the secondary cooling circuit (60) is controlled to a temperature above 100 ℃, preferably the temperature of the water in the secondary cooling circuit (60) is controlled to a temperature between 120 ℃ and 140 ℃.

26. The method of claim 25, wherein the engine is configured to operate at an engine load range between a minimum engine load and a maximum engine load, the method comprising: the temperature of the water in the secondary loop is controlled to a temperature above 100 ℃ at least for a maximum engine load, and preferably for an engine load between a medium engine load and a maximum engine load, and more preferably for an engine load between a minimum engine load and the maximum engine load, and preferably to a temperature between 120 ℃ and 140 ℃.

27. The method of claim 25 or 26, wherein controlling the temperature of the water in the secondary cooling circuit (60) comprises: by controlling the valve system (56, 57), the amount of water from the primary cooling circuit (70) that is mixed into the secondary cooling circuit (60) is regulated.

28. The method of any of claims 25 to 27, wherein the method comprises: a pressure of at least 5 bar is maintained in the primary cooling circuit (70) and the secondary cooling circuit (60).