Large-sized turbocharging two-stoke internal combustion engine for supplying mechanical energy and pressurized gas and method

Abstract

To provide a large-sized turbocharging two-stroke uniflow internal combustion engine for supplying pressurized scavenging air and / or pressurized exhaust emission to pressurized-gas consumer equipment, and a method for operating such an internal combustion engine.SOLUTION: A large-sized turbocharging two-stroke uniflow internal combustion engine for supplying pressurized scavenging air and / or pressurized exhaust emission to pressurized-gas consumer equipment comprises one or plurality of turbochargers, an air-scavenging and / or air-exhausting bypass system, and a controller for adjusting a bypass amount or the like, and adjusts a turbine flow area by adjusting a geometry of a variable geometry turbine of the turbocharger. The internal combustion engine also performs control for separating the one or a plurality of turbochargers in order to maximize pressure which is transmitted by a compressor at a partial load of the engine.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to a large turbocharged, two-stroke internal combustion engine and a method for operating such an engine, as well as a method for producing pressurized gas for other uses in addition to producing mechanical energy for propulsion, driving an electrical generator, etc.

[0002] Large turbocharged two-stroke self-igniting engines are often used in the propulsion systems of large ships and as prime movers in power plants. Their size, weight and power output set them apart from other combustion engines and place them in a unique category. These engines are constructed with a crosshead to avoid side pressure on the pistons, as increased height is less of a problem. Typically, such engines run on natural gas, petroleum gas, methanol, ethane or fuel oil.

[0003] Large turbocharged two-stroke auto-ignition engines for marine propulsion (marine engines) are tailored to support the installation of highly fuel efficient systems on board ships. In particular, waste heat recovery systems are important to reduce the overall fuel consumption of marine engines and to reduce emissions.

[0004] In some applications, in addition to producing mechanical energy for propulsion, engines are required to produce pressurized gases, e.g., pressurized air, pressurized exhaust, or a pressurized mixture of air and exhaust. One such application is air lubrication. Ships with large flat bottom areas can benefit from air lubrication by reducing resistance while moving. This can also benefit from reduced main engine power required to propel the ship at a given speed. Air lubrication systems generate a steady flow of air bubbles under the ship to lubricate the flat bottom area of ​​the ship's hull.

[0005] To achieve the desired reduction in power required for ship propulsion, a sufficient volume of air / gas according to the ship's design, at sufficient pressure, is required to be delivered to a dedicated bubbler interface. Conventionally tuned large two-stroke engines have limitations in providing sufficient pressurized air / gas at all required engine loads.

[0006] JP 2010-228679 A discloses a conventional engine adapted to divert scavenging air for use in a pressurized gas consumer.

[0007] It is an object of the present invention to provide a large turbocharged, two-stroke, uniflow internal combustion engine which overcomes or at least mitigates the above mentioned problems.

[0008] In order to avoid or at least reduce the installation and operation of costly air compressor units, a suitable two-stroke engine is proposed.

[0009] These and other objects are achieved by means of the features set forth in the independent claims. More particular implementations will become apparent from the dependent claims, the detailed description and the drawings.

[0010] According to a first aspect, there is provided a large turbocharged, two-stroke, uniflow internal combustion engine configured to supply pressurized scavenging air and / or pressurized exhaust gas to a consumer of pressurized gas. The engine comprises: a plurality of cylinders each having a scavenging port at a lower end and an exhaust valve at an upper end; an intake system having a scavenging receiver connected to the cylinder through the scavenging port, through which scavenging air is introduced into the cylinder; an exhaust system having an exhaust receiver connected to the cylinder through the exhaust valve, through which exhaust gas generated within the cylinder is exhausted; at least one turbocharger having an exhaust driven turbine operatively associated with a compressor, an inlet of the turbine connected to the exhaust system, and an outlet of the compressor connected to the intake system for delivering a pressurized scavenging flow to the intake system; a fuel system delivering fuel to the cylinder; a bypass system for taking a controlled amount of scavenging air from the intake system to bypass the engine and / or a controlled amount of exhaust gas from the exhaust system to bypass the turbine and supplying the bypassed pressurized gas to a consumer of pressurized gas; a controller coupled to the pressure sensor and / or the temperature sensor and configured to adjust the amount of bypass pressurized gas supplied to the consumer as a function of the sensed scavenging pressure and / or the sensed exhaust temperature; The controller comprises: · Increasing the turbocharger takeoff power provided by the turbohydraulic system; increasing the speed of an auxiliary blower in the intake system of the engine; increasing the speed of the EGR blower of the EGR system of said engine; · Activating an additional small turbocharger of said engine; opening a cylinder bypass valve of a cylinder bypass device of said engine; · opening an exhaust bypass to the power turbine unit of said engine to drive a dedicated electrically driven compressor; activating a hydraulically driven compressor powered by the hydraulic system of said engine; adjusting the geometry of a variable geometry turbine of the one or more turbochargers to adjust the turbine flow area, preferably by reducing the turbine flow area, in order to maximize the pressure delivered by the compressor under actual operating conditions of the engine; decoupling one or more of said one or more turbochargers, preferably as a function of engine load, in order to maximize the pressure delivered by said compressor at partial load of said engine; · activating one turbocharger below a first cut-off engine load threshold, activating two turbochargers between the first cut-off engine load threshold and a second cut-off engine load threshold, and activating three turbochargers at engine loads above the second cut-off engine load threshold; is configured to control the engine 100 in a manner that maximizes scavenging air pressure and / or mass flow of bypassed scavenging air by one or more of the following:

[0011] By providing a controller configured to apply various adjustment techniques to increase the pressure available at the engine for supplying gas to pressurized gas consumers, it becomes possible to maximize the amount of pressurized gas provided by the engine to the pressurized gas consumers without the risk of operating the engine in suboptimal conditions.

[0012] Considering that the bypass gas taken from the engine cycle essentially leads to an increase in the fuel consumption of the engine, an engine according to the first approach significantly improves the investment return potential of a ship using air lubrication. Moreover, by tuning the engine by one or more of the methods listed above to provide the highest possible scavenging pressure or the highest possible exhaust pressure, the engine can be transformed into a supply device that delivers pressurized gas to an external consumer of pressurized gas (e.g. an air lubrication system of a ship). This is much more efficient than using, for example, an air compressor driven by an electric drive motor. Moreover, by tuning the engine to provide the highest possible scavenging pressure or the highest possible exhaust pressure, the engine can be transformed into a supply device that delivers pressurized gas to an external consumer of pressurized gas (e.g. an air lubrication system of a ship). This is much more efficient than using, for example, an air compressor driven by an electric drive motor.

[0013] In a first possible implementation form of the first approach, the controller is configured to limit the amount of bypass pressurized gas supplied to the consumer when a detected or observed scavenging pressure is less than a scavenging pressure threshold or a detected or observed exhaust temperature is greater than an exhaust temperature threshold.

[0014] In one further implementation of the first approach, the controller is configured to determine an actual engine turbocharging efficiency as a function of sensed or observed scavenging pressure and / or sensed or observed exhaust temperature, where the term "engine turbocharging efficiency" refers to the turbocharging efficiency experienced or felt by the engine regardless of ambient conditions.

[0015] In one example of a further implementation of the first approach, the controller is configured to limit an amount of bypass pressurized gas supplied to the consumer as a function of the determined actual engine turbocharging efficiency.

[0016] In one example of a further implementation of the first approach, the controller is configured to determine an excess of the actual available efficiency of the one or more turbochargers compared to a predefined minimum engine turbocharging efficiency threshold.

[0017] In one example of a further implementation of the first approach, the controller is configured to limit an amount of bypass pressurized gas supplied to the consumer as a function of the determined excess.

[0018] In one further implementation of the first approach, the control unit is configured to adjust the amount of bypass pressurized gas supplied to the pressurized gas consumer in response to a need for pressurized gas by the pressurized gas consumer, preferably in response to a signal from the pressurized gas consumer, preferably within a range not exceeding a threshold value.

[0019] In one example of a further implementation of the first aspect, the one or more turbochargers have a turbocharging efficiency that exceeds a minimum required predefined engine turbocharging efficiency, at least in a range of engine loads.

[0020] In one example of a further implementation of the first aspect, the one or more turbochargers have a variable geometry turbine that allows adjusting a turbine flow area, the control unit is connected to the one or more turbochargers for controlling the variable geometry of the turbine, and the control unit is configured to adjust the geometry of the turbine in order to maximize the pressure delivered by the compressor under actual operating conditions of the engine, preferably by reducing the turbine flow area.

[0021] In one example of a further implementation of the first approach, the engine includes two or more turbochargers, and the control unit is configured to disengage one or more of the two or more turbochargers to maximize pressure delivered by the compressor at partial load of the engine, and the control unit is configured to disengage one or more of the two or more turbochargers as a function of load of the engine.

[0022] In one further implementation of the first approach, a switch point for disengaging one or more of the two or more turbochargers is provided in a range of 60-80% of engine load, and the controller is configured to disengage one or more of the two or more turbochargers when the engine load falls below the switch point. Additional turbochargers may be added in a similar manner.

[0023] In one example of a further implementation of the first approach, the controller can be connected to a first electronically controlled valve and control the first electronically controlled valve to control the amount of scavenging air taken from the intake system, and / or the controller can be connected to a second electronically controlled valve and control the second electronically controlled valve to control the amount of exhaust gas taken from the exhaust system.

[0024] In one further implementation of the first approach, engine part load covers a range from 20% to 80% of the engine's maximum continuous rating.

[0025] In one further implementation of the first approach, the controller is configured to reduce the amount of bypass pressurized gas supplied to the consumer when the detected scavenge pressure is below a scavenge pressure threshold, the scavenge pressure threshold being preferably adjusted according to ambient conditions.

[0026] In one further implementation of the first approach, the controller is configured to reduce an amount of bypass pressurized gas supplied to the consumer when a sensed exhaust temperature exceeds an exhaust temperature threshold, the exhaust temperature threshold being preferably adjusted according to ambient conditions.

[0027] In one further implementation of the first approach, engine part loads cover a range from 20% to 800% of the engine's Maximum Continuous Rating.

[0028] In one example of a further implementation form of the first approach, the engine has a pressure sensor for detecting the scavenging air pressure in the intake system, preferably inside or immediately upstream of the scavenging air receiver, and / or a temperature sensor for detecting the exhaust temperature in the exhaust system, preferably inside or immediately downstream of the exhaust air receiver, and / or an observer for estimating the scavenging air pressure in the intake system, preferably inside or immediately upstream of the scavenging air receiver, and / or an observer for estimating the temperature of the exhaust system, preferably inside or immediately downstream of the exhaust air receiver.

[0029] According to a second aspect, there is provided a method of operating a large turbocharged two-stroke uniflow internal combustion engine for supplying pressurized scavenging air and / or pressurized exhaust air from said engine to a consumer of pressurized gas, said engine comprising: a plurality of cylinders each having a scavenging port at a lower end and an exhaust valve at an upper end; an intake system having a scavenging receiver connected to the cylinder through the scavenging port, through which scavenging air is introduced into the cylinder; an exhaust system having an exhaust receiver connected to the cylinder through the exhaust valve, through which exhaust gas generated within the cylinder is exhausted; one or more turbochargers having an exhaust driven turbine operatively associated with a compressor, an inlet of the turbine connected to the exhaust system, and an outlet of the compressor connected to the intake system for delivering a pressurized scavenging flow to the intake system; a bypass system for supplying bypassed pressurized gas to a consumer of the pressurized gas; And the method comprises: bypassing a controlled amount of scavenging air from the intake system or bypassing a controlled amount of exhaust air from the exhaust system; One or more of the following: Increasing the turbocharger takeoff power provided by the turbo hydraulic system; increasing the speed of an auxiliary blower in the intake system of the engine; increasing the speed of the EGR blower of the EGR system of said engine; activating an additional small turbocharger of said engine; opening a cylinder bypass valve of a cylinder bypass device of said engine; Opening an exhaust bypass to the power turbine unit of said engine to drive a dedicated electrically driven compressor; activating a hydraulically driven compressor powered by the hydraulic system of said engine; adjusting the geometry of a variable geometry turbine to adjust the turbine flow area in order to maximize the pressure delivered by the compressor under actual operating conditions of the engine, preferably by reducing the turbine flow area; decoupling one or more of said one or more turbochargers in order to maximize the pressure delivered by said compressor at partial load of said engine, preferably as a function of engine load; activating one turbocharger below a first cut-off engine load threshold, activating two turbochargers between the first cut-off engine load threshold and a second cut-off engine load threshold, and activating three turbochargers at engine loads above the second cut-off engine load threshold; maximizing the scavenging air pressure and / or mass flow of bypassed scavenging air; Includes.

[0030] In one example of an implementation of the second approach, the method includes: sensing a scavenging pressure in the intake system, preferably within or immediately upstream of the scavenging receiver, and / or sensing an exhaust temperature in the exhaust system, preferably within or immediately downstream of the scavenging receiver; adjusting the amount of bypassed pressurized gas supplied to said consumer as a function of the sensed scavenging pressure and / or exhaust temperature; Includes.

[0031] In one example of an implementation of the second approach, the method includes: estimating a scavenging pressure in the intake system, preferably within or immediately upstream of the scavenging receiver, and / or estimating an exhaust temperature in the exhaust system, preferably within or immediately downstream of the scavenging receiver; adjusting the amount of bypassed pressurized gas supplied to said consumer as a function of the sensed scavenging pressure and / or exhaust temperature; Includes.

[0032] The above and other aspects of the present invention will become more apparent from the embodiments described below. [Brief description of the drawings]

[0033] The invention will now be explained in more detail with reference to exemplary embodiments shown in the drawings. [Figure 1] FIG. 1 shows a front view of a large two-stroke internal combustion engine according to an exemplary embodiment. [Diagram 2] FIG. 2 is a diagram showing an overview of the large two-stroke internal combustion engine of FIG. 1 as seen from the side. [Diagram 3] FIG. 2 is a schematic representation of a large two-stroke internal combustion engine. [Figure 4] 1 is a schematic representation of an embodiment of a two-stroke internal combustion engine with multiple turbochargers in which turbocut is implemented. [Diagram 5] 1 is a schematic representation of an embodiment of a two-stroke internal combustion engine with a variable geometry turbocharger. Detailed explanation

[0034] 1-3 depict a turbocharged large slow-speed two-stroke diesel engine 100. The engine has a crankshaft 8 and a crosshead 9. FIG. 3 is a schematic representation of a turbocharged large slow-speed two-stroke diesel engine together with its intake and exhaust systems. In this embodiment 100, the engine has six cylinders 1 in series. A turbocharged large slow-speed two-stroke diesel engine usually has 4 to 14 cylinders arranged in series. These cylinders are carried in a cylinder frame 23. The cylinder frame 23 is carried in an engine frame 11. The engine 100 can be used, for example, as a main engine of a ship or as a stationary engine for driving a generator in a power plant. The total power output of the engine 100 can be, for example, between 1000 kW and 110000 kW.

[0035] The engine 100 in this embodiment is a two-stroke uniflow compression ignition engine, with each cylinder liner 1 having a scavenge port 18 in its lower region and an exhaust valve at the top center. However, the engine 100 does not necessarily have to be compression ignition, and in some embodiments may be spark ignition. In the embodiment presented here, the compression pressure of the engine 100 is high enough to provide compression ignition. However, the engine 100 may also operate at a lower compression pressure and be ignited by a spark or similar means.

[0036] The intake system of the engine 100 includes a scavenging air receiver 2. Scavenging air is guided to a scavenging port 18 of each cylinder 1 through the scavenging air receiver 2. A piston 10 reciprocates between bottom dead center (BDC) and top dead center (TDC) in the cylinder liner 1, compressing the scavenging air. Fuel is injected from a fuel valve 50 disposed in a cylinder cover 22. Following fuel injection, combustion occurs, generating exhaust gas.

[0037] The exhaust valve 4 is located in the center of the cylinder cover 22. A number of fuel valves 55 are arranged around the central exhaust valve. The exhaust valve 4 is actuated by an electro-hydraulic exhaust valve actuation system (not shown) controlled by a controller 50. The fuel valves 55 are part of a fuel supply system. The controller 50 is also configured to control the operation of the fuel valves 55.

[0038] When the exhaust valve 4 opens, the exhaust gas flows through an exhaust system including an exhaust duct in the cylinder 1 to an exhaust receiver 3 and then through a first exhaust pipe 19 to a turbine 8 of the turbocharger 5. From there, the exhaust gas flows through a second exhaust pipe 25 to an economizer 20 and is then discharged to the atmosphere through an outlet 21. Note that in some embodiments, the engine 100 includes multiple turbochargers 5.

[0039] The turbine 8 drives the compressor 7 via a shaft. The compressor 9 is supplied with outside air through an air intake 12. The compressor 7 sends the compressed scavenging air to a scavenging pipe 13 connected to the scavenging air receiver 2. The scavenging air in the scavenging pipe 13 passes through an intercooler 14 for cooling the scavenging air.

[0040] The cooled scavenging air passes through an auxiliary blower 16 driven by an electric motor 17. The auxiliary blower 16 compresses the scavenging air flow when the compressor 7 of the turbocharger 5 cannot provide sufficient pressure for the scavenging air receiver 2, i.e. when the engine 100 is at low or partial load. At high engine loads, the turbocharger compressor 7 can provide sufficiently compressed scavenging air, so that the auxiliary blower 16 is switched off and bypassed by the check valve 15.

[0041] 4 and 5, a large marine engine 100 (i.e., a large turbocharged two-stroke uniflow internal combustion engine 100) is configured to supply scavenging air and / or exhaust to a pressurized gas consumer 200. In this embodiment, configurations and features similar to those already described or illustrated are given the same reference numerals as before. The pressurized gas consumer 200 can be, for example, an air lubrication system of a ship on which the large marine engine 100 is mounted, for reducing the resistance of the ship while it is sailing.

[0042] Scavenging air is introduced into the cylinder 1 through an intake system. The intake system includes a scavenging air receiver 2 connected to the cylinder 1 via a scavenging port 18.

[0043] The exhaust gas generated in the cylinder is exhausted through an exhaust system comprising an exhaust receiver 3 connected to the cylinder 1 via an exhaust valve 4.

[0044] The bypass system supplies the branched pressurized gas to the pressurized gas consumer 200. This is done by taking a controlled amount of scavenging air from the intake system (i.e. bypassing the engine 100). For this purpose, a first bypass pipe 43 is connected to the intake system at a location downstream of the outlet of the compressor 7 (e.g. to the scavenging receiver 2 as shown). In this embodiment, the first bypass pipe 43 is provided with a first bypass control valve 41 and is connected to the pressurized gas consumer 200. In some embodiments, the first bypass pipe 43 is provided with a first bypass blower (compressor) 47. If the amount of pressurized gas provided by the engine 100 is not sufficient to meet the demand of the pressurized gas consumer 200 without the aid of the first bypass blower 47, the first bypass blower 47 is activated. Preferably, one or both of the first bypass control valve 41 and the first bypass blower 47 are controlled by a controller 50. The bypass pipe includes a first check valve 45 that allows bypassing the first bypass blower 47 when its assistance is not needed. The intake system is provided with a pressure sensor 34 for sensing the pressure in the intake system downstream of the compressor 7. A signal from the pressure sensor 34 is communicated to the controller 50, for example by a signal line. The pressure sensor 34 may be located in the scavenge air receiver 2 or just upstream of the scavenge air receiver 2. In some embodiments, an observer (not shown), which may be part of the controller 50, estimates the pressure in the intake system (e.g. the pressure in the scavenge air receiver), and the controller 50 may use the estimated pressure to determine the pressure to use.

[0045] In some embodiments, the bypass system takes a controlled amount of pressurized exhaust from the exhaust system and bypasses the turbine. This configuration may be implemented in combination with the previous embodiments. To this end, a second bypass pipe 49 is connected to the exhaust system at a location upstream of the inlet of the turbine 8 (e.g. exhaust receiver 3 as shown). In this embodiment, the second bypass pipe 49 comprises a second bypass control valve 42 and is connected to a pressurized gas consumer 200. In some embodiments, the second bypass pipe 49 comprises a second bypass blower (compressor) 46. The second bypass blower 46 is activated when the amount of pressurized gas provided by the engine 100 is not sufficient to meet the demand of the pressurized gas consumer 200 without the aid of the second bypass blower 46. The bypass pipe comprises a second check valve 44 that allows bypassing the second bypass blower 46 when the aid of the second bypass blower 46 is not required. Preferably, one or both of the second bypass control valve 42 and the second bypass blower 46 are controlled by a controller 50. The exhaust system is provided with a temperature sensor 33 for sensing the temperature of the exhaust system upstream of the turbine 8. A signal from the temperature sensor 33 is communicated to the controller 50, for example by a signal line. The temperature sensor 33 may be arranged to sense the temperature in the exhaust receiver 3 or just downstream of the exhaust receiver 3. In some embodiments, an observer (not shown), which may be part of the controller 50, may estimate the temperature in the exhaust system, and the controller 50 may use the estimated temperature to determine the exhaust temperature to use.

[0046] The controller 50 is configured to apply the monitored adjustments to maximize the scavenging pressure provided by the one or more turbines 7 of the turbocharging system 5 .

[0047] The controller 50 is configured to adjust the amount of pressurized gas bypassed for supply to the consumer 200 as a function of the scavenging pressure and / or the exhaust temperature sensed by the sensor or estimated by the observer, in particular to apply said adjustments to limit the amount of pressurized gas bypassed in the event that the scavenging pressure falls below a threshold value or the exhaust temperature exceeds a threshold value.

[0048] The controller 50 is therefore configured to limit the amount of bypass pressurized gas supplied to the pressurized gas consumer 200 when the sensed scavenge pressure is below the scavenge pressure threshold or the sensed exhaust temperature is above the exhaust temperature threshold.

[0049] In some embodiments, the controller 50 is configured to determine an engine turbocharging efficiency as a function of the sensed scavenging pressure and / or the sensed exhaust temperature, and to limit the amount of bypass pressurized gas supplied to the pressurized gas consumer 200 as a function of the determined engine turbocharging efficiency. The controller 50 is preferably configured to limit the amount of bypass pressurized gas supplied to the pressurized gas consumer 200 when the determined engine turbocharging efficiency is lower than an engine turbocharging efficiency threshold.

[0050] The controller 50 is preferably configured to determine an actual available efficiency excess for one or more turbochargers 5 compared to a predefined minimum engine turbocharging efficiency threshold, and to limit the amount of bypass pressurized gas supplied to the pressurized gas consumer 200 as a function of the determined excess.

[0051] In some embodiments, the controller 50 is configured to adjust the amount of bypass pressurized gas supplied to the pressurized gas consumer 200 in response to a need for pressurized gas by the pressurized gas consumer 200. Preferably, the controller 50 is configured to adjust in response to a signal from the pressurized gas consumer 200, without exceeding the determined excess.

[0052] Preferably, the turbocharger(s) 5 have a turbocharging efficiency that exceeds a minimum required predetermined engine turbocharging efficiency, at least in a range of engine loads.

[0053] 5, the turbocharger(s) 5 have a variable geometry turbine 8, allowing for adjustment of the turbine flow area. A controller 50 is connected to the turbocharger(s) 5 and controls the variable geometry turbine 8. The control unit 50 is also configured to control the variable geometry turbine 8 to maximize the pressure delivered by the compressor 7 (preferably by reducing the turbine flow area) under the actual operating conditions of the engine 100 (sensed by the controller 50).

[0054] In the embodiment of Figure 4, the engine 100 comprises two or more turbochargers 5. The controller 50 is then configured to disengage one or more of these two or more turbochargers 5 in order to maximise the pressure delivered by the compressor 7 at part load conditions of the engine 100. The control unit 50 is preferably configured to disengage one or more turbochargers 5 as a function of the engine load.

[0055] A switch point for disengaging one or more of the two or more turbochargers 5 is provided in the range of 60-80% of the engine load. The controller 50 is configured to disengage one or more of the two or more turbochargers 5 when the engine load falls below the switch point. The switch point for disengaging the turbochargers can be optimized (shifted toward higher engine loads) for different installations and frame sizes of the turbochargers 5.

[0056] In a not shown embodiment, the engine 100 comprises more than two turbochargers 5, and the controller 50 is configured to activate one turbocharger 5 below a first cut-off engine load threshold, so that at low engine loads only one turbocharger 5 with an appropriate flow area operates. The controller 50 is also configured to activate two turbochargers 5 between the first cut-off engine load threshold and a second cut-off engine load threshold, because the combination of flow areas of these two turbochargers 5 is appropriate at medium engine loads. The controller 50 is further configured to activate three turbochargers 5 at engine loads above the second cut-off engine load threshold, because the combination of flow areas of the activated turbochargers 5 is compatible with the operating conditions. The activation sequence can be optimized according to the flow areas of the turbochargers 5, and the number of turbochargers 5 is not limited to three, but may be four, five or more. The operation of the engine can be optimized by switching the turbochargers 5 on and off in a specific sequence. Depending on the load, it can be optimized by operating only one turbocharger 5 or a combination of turbochargers 5 that provides the most suitable flow area. For example, when the load is increasing, the turbochargers 5 are switched on individually in stages to increase the total flow area. When the maximum load of the engine is approached, all turbochargers 5 are activated.

[0057] The controller 50 may be connected to the first electronically controlled valve 41 and control the first electronically controlled valve 41 in order to control the amount of scavenging air taken in from the intake system, and / or may be connected to the second electronically controlled valve 42 and control the second electronically controlled valve 42 in order to control the amount of exhaust gas taken in from the exhaust system.

[0058] In some embodiments, the controller 50 is configured to reduce the amount of bypass pressurized gas provided to the consumer 200 when the sensed sweep pressure is less than the sweep pressure threshold. The sweep pressure threshold is preferably adjusted according to ambient conditions. A lowest threshold applies for arctic conditions and a highest threshold applies for tropical conditions. In some embodiments, the appropriate sweep pressure threshold level and the adjustment of the sweep pressure threshold are based on testing or simulation of the engine 100.

[0059] In some embodiments, controller 50 is configured to reduce the amount of bypass pressurized gas provided to consumer 200 when the sensed exhaust temperature exceeds the exhaust temperature threshold. The exhaust temperature threshold is preferably adjusted according to ambient conditions. A lowest exhaust temperature threshold applies for arctic conditions and a highest exhaust temperature threshold applies for tropical conditions. In some embodiments, the appropriate level of the exhaust temperature threshold and the adjustment of the exhaust temperature threshold are based on testing or simulation of engine 100.

[0060] In the embodiment depicted in FIG. 5, the engine 100 includes turbochargers 5 with variable geometry turbines 8 allowing adjustment of the turbine flow area. The controller 50 is configured to adjust the turbine flow area to maximize the pressure delivered by the compressors 7. This is preferably done by reducing the turbine flow area of ​​all turbochargers 5 to maximize the pressure delivered by the compressors 7 at part load conditions of the engine 100. In this embodiment, the engine 100 is provided with an optional exhaust gas recirculation (EGR) system. The EGR system includes an EGR unit 60, an EGR blower 29, and an EGR valve 32. The EGR blower 29 and the EGR valve 32 are electronically controlled under the command of the controller 50. The EGR unit 60 includes elements for treating the recirculated exhaust gas, such as an EGR cooler 62, an EGR scrubber, and a water mist catcher 63.

[0061] In some embodiments, the controller 50 is configured to control the engine 100 in a manner to maximize scavenging air pressure and / or maximize the mass flow of bypassed scavenging air by controlling a Power Take In (PTI) function of a Turbo Hydraulic System (THS) device in one or more turbochargers 5.

[0062] In some embodiments, the controller 50 is configured to control the engine 100 in a manner that maximizes scavenging pressure and / or mass flow of bypassed scavenging air by controlling the auxiliary blower device 16 to add pressure at higher than normal loads.

[0063] In some embodiments, the controller 50 is configured to control the engine 100 in a manner that maximizes the scavenging pressure and / or the mass flow of bypassed scavenging air using the high turbocharging efficiency of the two-stage turbocharger.

[0064] In some embodiments, the controller 50 is configured to control the engine 100 in a manner that maximizes scavenging pressure by controlling the cylinder bypass valve arrangement for pressurization.

[0065] In some embodiments, the controller 50 is configured to control the engine 100 in a manner that maximizes exhaust bypass pressure by controlling the function of the EGR blower 29 of the EGR system of the Tier 3 EGR engine 100 for additional boost in Tier 2 mode.

[0066] In some embodiments, the controller 50 is configured to control the engine 100 in a manner that maximizes the delivered gas pressure by controlling an additional small turbocharger to pressurize additional fresh air or bypassed scavenging air.

[0067] In some embodiments, the controller 50 is configured to control the engine 100 in a manner that maximizes the delivered gas pressure by controlling the exhaust bypass to a power turbine device to drive a dedicated additional electric compressor.

[0068] In some embodiments, the controller 50 is configured to control the engine 100 in a manner that maximizes the delivered gas pressure and / or mass flow by controlling a hydraulic compressor operated by the engine's hydraulic system.

[0069] The engine 100 is operated according to a method that includes bypassing a controlled amount of scavenging air from the intake system or bypassing a controlled amount of exhaust from the exhaust system. The scavenging pressure in the intake system and / or the exhaust temperature in the exhaust system are sensed. The amount of bypassed pressurized gas supplied to the consumer 200 is adjusted as a function of the sensed scavenging pressure and / or exhaust temperature.

[0070] The various approaches introduced above for optimizing the performance of the engine of the embodiments can be combined, for example sequential turbocharging (turbocharging on and off) can be combined with adjusting the turbine flow area of ​​one or more variable geometry turbines.

[0071] The method and apparatus have been described with several embodiments. However, upon review of the specification, drawings, and claims of this application, those skilled in the art will understand and be able to embody many variations in addition to the described embodiments in implementing the claimed invention. The words "comprise", "have", and "include" in the claims do not exclude the presence of elements or steps not recited. The absence of a plurality of elements recited in a claim does not exclude the presence of a plurality of the elements. The functions of several elements recited in the claims may be performed by a single controller or other unit. The fact that several items are recited in separate dependent claims does not exclude them from being implemented in combination, and may be implemented to advantage in combination. The signs used in the claims should not be interpreted as limiting the scope of the invention.

Claims

1. 1. A large turbocharged two-stroke uniflow internal combustion engine configured to supply pressurized scavenging air and / or pressurized exhaust to a pressurized gas consumer, said engine comprising: a plurality of cylinders each having a scavenging port at a lower end and an exhaust valve at an upper end; an intake system having a scavenging air receiver connected to the cylinder through the scavenging port, through which scavenging air is introduced into the cylinder; an exhaust system having an exhaust receiver connected to the cylinder through the exhaust valve, through which exhaust gas generated within the cylinder is exhausted; one or more turbochargers each having an exhaust driven turbine operatively associated with a compressor, an inlet of the turbine connected to the exhaust system, and an outlet of the compressor connected to the intake system for delivering a pressurized scavenging flow to the intake system; a fuel system delivering fuel to the cylinder; a bypass system for extracting a controlled amount of scavenging air from the intake system to bypass the engine and / or extracting a controlled amount of exhaust from the exhaust system to bypass the turbine, and supplying the bypassed pressurized gas to the pressurized gas consumer; a controller coupled to the pressure sensor and / or the temperature sensor and configured to adjust the amount of bypass pressurized gas supplied to the pressurized gas consumer as a function of the sensed scavenging pressure and / or the sensed exhaust temperature; The controller comprises: - Increasing turbocharger takeoff power provided by the turbo hydraulic system; - increasing the speed of an auxiliary blower in the intake system of the engine; increasing the speed of an EGR blower of the EGR system of said engine; - activating an additional small turbocharger of said engine; opening an exhaust bypass to the engine's power turbine unit to drive a dedicated electrically driven compressor; - activating a hydraulically driven compressor powered by the hydraulic system of said engine; - disconnecting one or more of the one or more turbochargers to increase the pressure delivered by the compressor at part load of the engine; activating one turbocharger below a first cut-off engine load threshold, activating two turbochargers between the first cut-off engine load threshold and a second cut-off engine load threshold, and activating three turbochargers at engine loads above the second cut-off engine load threshold; 4. An engine configured to control the engine in a manner to increase scavenging air pressure and increase bypassed scavenging air mass flow by one or more of:

2. 2. The engine of claim 1, wherein the controller is configured to limit the amount of bypass pressurized gas supplied to the pressurized gas consumer when a sensed or observed scavenging pressure is less than a scavenging pressure threshold and / or a sensed exhaust temperature is greater than a exhaust temperature threshold.

3. 3. An engine according to claim 1 or 2, wherein the controller is configured to determine an actual engine turbocharging efficiency as a function of sensed or observed scavenging pressure and / or sensed or observed exhaust temperature.

4. The apparatus of claim 3 , wherein the controller is configured to limit an amount of bypass pressurized gas supplied to the pressurized gas consumer as a function of the determined actual engine turbocharging efficiency.

5. 4. The apparatus of claim 3, wherein the controller is configured to reduce or limit an amount of bypass pressurized gas supplied to the pressurized gas consumer when the determined actual engine turbocharging efficiency is below an engine turbocharging actual efficiency threshold.

6. 6. An engine as claimed in any one of claims 1 to 5, wherein the controller is configured to determine an excess of an actually available efficiency of the one or more turbochargers compared to a predefined minimum engine turbocharging efficiency threshold, wherein the excess is the difference between the actually available efficiency and the predefined minimum engine turbocharging efficiency threshold.

7. The engine of claim 6 , wherein the controller is configured to limit an amount of bypass pressurized gas supplied to the pressurized gas consumer as a function of the determined excess.

8. An engine according to any preceding claim, wherein the controller is configured to adjust the amount of bypass pressurized gas supplied to the pressurized gas consumer in response to a signal from the pressurized gas consumer.

9. An engine according to any preceding claim, wherein the one or more turbochargers have a turbocharging efficiency that exceeds a minimum required predefined engine turbocharging efficiency, at least in a range of engine loads.

10. 10. An engine according to any preceding claim, wherein a switch point for disengagement of one or more of the two or more turbochargers is provided in the range of 60-80% of engine load, and the controller is configured to disengage one or more of the two or more turbochargers when engine load falls below said switch point.

11. 11. An engine according to any one of claims 1 to 10, wherein the controller is connected to a first electronically controlled valve and is capable of controlling the first electronically controlled valve to control the amount of scavenging air taken from the intake system, and / or the controller is connected to a second electronically controlled valve and is capable of controlling the second electronically controlled valve to control the amount of exhaust gas taken from the exhaust system.

12. 12. An engine according to any preceding claim, wherein the controller is configured to reduce an amount of bypass pressurized gas supplied to the pressurized gas consumer when the sensed scavenging pressure is less than a threshold scavenging pressure.

13. 13. The engine of claim 12, wherein the sweep pressure threshold is adjusted if ambient conditions are polar or tropical.

14. The engine of claim 2 , wherein the exhaust temperature threshold is adjusted if ambient conditions are polar or tropical.

15. 15. An engine according to claim 1, further comprising a pressure sensor for detecting a scavenging pressure in the intake system and / or a temperature sensor for detecting an exhaust temperature in the exhaust system.

16. 1. A method of operating a large turbocharged two-stroke uniflow internal combustion engine for supplying pressurized scavenging air and / or pressurized exhaust air from said engine to a pressurized gas consumer, comprising: a plurality of cylinders each having a scavenging port at a lower end and an exhaust valve at an upper end; an intake system having a scavenging air receiver connected to the cylinder through the scavenging port, through which scavenging air is introduced into the cylinder; an exhaust system having an exhaust receiver connected to the cylinder through the exhaust valve, through which exhaust gas generated within the cylinder is exhausted; one or more turbochargers having an exhaust driven turbine operatively associated with a compressor, an inlet of the turbine connected to the exhaust system, and an outlet of the compressor connected to the intake system for delivering a pressurized scavenging flow to the intake system; a bypass system for supplying bypassed pressurized gas to the pressurized gas consumer; The method comprises: bypassing a controlled amount of scavenging air from the intake system or bypassing a controlled amount of exhaust air from the exhaust system; One or more of the following: - increasing the turbocharger takeoff power provided by the turbo hydraulic system; increasing the speed of an auxiliary blower in the intake system of the engine; increasing the speed of an EGR blower of the EGR system of said engine; activating an additional small turbocharger of said engine; opening an exhaust bypass to the engine's power turbine unit to drive a dedicated electrically driven compressor; activating a hydraulically driven compressor powered by the hydraulic system of the engine; - disconnecting one or more of the one or more turbochargers to increase the pressure delivered by the compressor at part load of the engine; activating one turbocharger below a first cut-off engine load threshold, activating two turbochargers between the first cut-off engine load threshold and a second cut-off engine load threshold, and activating three turbochargers at engine loads above the second cut-off engine load threshold; increasing the scavenging air pressure and increasing the mass flow of the bypassed scavenging air; A method comprising:

17. sensing a scavenging pressure within the intake system; adjusting an amount of bypassed pressurized gas supplied to the pressurized gas consumer as a function of the sensed scavenging pressure; 17. The method of claim 16, comprising:

18. estimating a scavenging pressure in the intake system and / or estimating an exhaust temperature in the exhaust system; adjusting the amount of bypassed pressurized gas supplied to the pressurized gas consumer as a function of the estimated scavenging pressure and / or exhaust temperature; 17. The method of claim 16, comprising:

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