DK181374B1

DK181374B1 - Method and large turbocharged two-stroke internal combustion engine for delivering mechanical energy and pressurized gas

Info

Publication number: DK181374B1
Application number: DKPA202270080A
Authority: DK
Inventors: Schmuttermair Herbert
Original assignee: Man Energy Solutions Filial Af Man Energy Solutions Se Tyskland
Priority date: 2022-03-02
Filing date: 2022-03-02
Publication date: 2023-09-14
Also published as: DK202270080A1

Abstract

A large turbocharged two-stroke internal combustion engine (100) of the uniflow type configured to supply pressurized scavenging gas and/or exhaust gas to a consumer of pressurized gas (200) and a method for operating such an engine (100).

Description

. DK 181374 B1

METHOD AND LARGE TURBOCHARGED TWO-STROKE INTERNAL

COMBUSTION ENGINE FOR DELIVERING MECHANICAL ENERGY AND

PRESSURIZED GAS

TECHNICAL FIELD

The present disclosure relates a method and large turbocharged two-stroke internal combustion engine configured to produce pressurized gas for use in another application in addition to mechanical energy e.g. for propulsion or driving an electric generator and to a method of operating such an engine.

BACKGROUND

Large turbocharged two-stroke self-igniting internal combustion engines are typically used in propulsion systems of large ships or as a prime mover in power plants. Their sheer size, weight, and power output render them completely different from common combustion engines and place large two-stroke turbocharged compression-ignited internal combustion engines in a class for themselves. The height of these engines is typically not crucial, and therefore they are constructed with crossheads in order to avoid lateral loads on the pistons. Typically, these engines are operated with natural gas, petroleum gas, methanol, ethane, or fuel oil.

Large turbocharged two-stroke self-igniting internal combustion engines for ship propulsion (marine engines) are tuned in order to support certain fuel-efficient system installations onboard a vessel. In particular, waste heat recovery systems are relevant for the reduction of overall energy consumption and reducing emissions from the marine engine.

, DK 181374 B1

In certain applications, the engine is required to provide pressurized gas, e.g. pressurized air, pressurized exhaust gas, or a mixture of pressurized air and exhaust gas, in addition to providing mechanical energy e.g. for propulsion. One such application is air lubrication. Marine vessels with a large flat bottom area can take advantage of reducing the resistance when moving through the water by air lubrication, and thereby the needed main engine power to propel the vessel at a given speed. The air lubrication system pumps a steady flow of air bubbles beneath the ship’s hull to lubricate the flat bottom area of the ship’s hull.

To achieve the desired reduction in the power needed for ship propulsion, delivery of sufficient air/gas amount at sufficient pressure according to the vessel/s draft to the dedicated air-bubble generator interface is needed. Large two-stroke engines with standard tuning are often limited to provide sufficient pressurized air/gas at all required engine loads.

EP2272747 dislcoses a gas injection control device that performs, for example, control reflecting variation in vessel velocity over time without adversely affecting the main engine is realized. That is, it is prevented that gas is drawn too much and thereby a gas supply or charged air rate becomes insufficient, efficiency of the main engine is decreased and exhaust gas is deteriorated, and analogous events occur because the gas supply or charged air rate is too much instead. There are provided a main engine acquiring propelling power for a vessel, and a turbocharger that is driven by exhaust gas from the main engine and blows pressurized gas to the main engine. A part of the pressurized gas and/or exhaust gas is drawn from between

DK 181374 B1 the turbocharger and the main engine. The drawn pressurized gas and/or exhaust gas are injected in the proximity of the hull on or below the waterline, and the drawing rate of the pressurized gas and/or the exhaust gas is controlled on the 5 basis of a physical quantity related to a heat load on the main engine and characteristics of the turbocharger.

JP2010228679A discloses a conventionally tuned engine according to the preamble of claim 1.

SUMMARY

It is an object of the invention to provide a large turbocharged two-stroke internal combustion engine of the uniflow type that overcomes or at least reduces the problems indicated above.

In order to avoid or at least reduce costly air compressor unit installation and operation, an adapted two-stroke engine is proposed.

The foregoing and other objects are achieved by the features of the independent claims. Further implementation forms are apparent from the dependent claims, the description, and the figures.

According to a first aspect, there is provided a large turbocharged two-stroke internal combustion engine of the uniflow type, the engine being configured to supply pressurized scavenging gas and/or exhaust gas to a consumer of pressurized gas, the engine comprising: a plurality of cylinders with scavenge ports at their lower end and an exhaust valve at their upper end, an intake system through which scavenging gas is introduced into the cylinders, the intake system comprising a scavenge

2 DK 181374 B1 gas receiver connected to the cylinders via the scavenge ports, an exhaust system through which exhaust gas produced in the cylinders is exhausted, the exhaust system comprising an exhaust gas receiver connected to the cylinders via the exhaust valves, at least one turbocharger having an exhaust gas-driven turbine operably coupled to a compressor, with an inlet of the turbine connected to the exhaust system and an outlet of the compressor connected to the intake system for delivering a flow of pressurized scavenge gas to the intake system, a fuel system for delivering fuel to the cylinders, a bypass system for supplying bypassed pressurized gas to the consumer of pressurized gas by taking out a controlled amount of scavenging gas from the intake system thereby bypassing the engine and/or by taking out a controlled amount of pressurized exhaust gas from the exhaust system thereby bypassing the turbine, anda controller coupled to a pressure sensor for sensing scavenging gas pressure and/or a temperature sensor for sensing exhaust gas temperature, the controller being configured to adjust the amount of bypassed pressurized gas supplied to the consumer as a function of the sensed scavenging gas pressure and/or exhaust gas temperature, wherein the controller is configured to operate the engine in a way to maximize scavenging gas pressure and/or maximize scavenging gas bypass mass-flow by one or more of: - increasing the speed of an auxiliary blower in the intake system of the engine, - increasing the speed of an EGR blower in an EGR installation of the engine, - opening a cylinder bypass valve in a cylinder bypass installation of the engine,

- DK 181374 B1 - opening an exhaust gas bypass to a power turbine installation of the engine for driving a dedicated electrically driven compressor, - adjusting the geometry and thereby the turbine flow area of a variable geometry turbine of the one or more turbochargers to maximize the pressure delivered by the compressor under the actual operating conditions of the engine, preferably by reducing the turbine flow area, - cutting-out one or more of the one or more turbochargers, to maximize the pressure delivered by the compressor under partial load conditions of the engine, preferably as a function of the engine load, - activating one turbocharger below a first cutout engine load threshold, activating two turbochargers in an interval between the first cutout engine load threshold and a second cutout engine load threshold, and activating three turbochargers above the second cutout engine load threshold.

By providing a controller configured to apply a variety of tuning measures that increase the pressure available in the engine for supplying gas to a consumer of pressurized gas, it becomes possible to maximize the amount of pressurized gas delivered by the engine for the consumer of pressurized gas, without risking the engine running at sub-optimal conditions. Considering that the bypass gas taken from the engine cycle leads inherently to an increase of the engine’s fuel consumption, the business case potential of a marine vessel with air lubrication is considerably enhanced by the engine according to the first aspect.

Further, by tuning the engine by one or more of the listed measures to provide the highest possible scavenging pressure or the highest possible exhaust gas pressure, the engine can be transformed into a supplier of pressurized

. DK 181374 B1 gas for delivery to an external consumer of pressurized gas, such as an air lubrication system of a marine vessel, which is much more effective compared to the use of e.g. air compressors driven by an electric drive motor.

In a first possible implementation form of the first aspect, the controller is configured to limit the amount of bypassed pressurized gas supplied to the consumer when the sensed scavenging pressure is below a scavenging pressure threshold and/or the sensed exhaust gas temperature is above an exhaust gas temperature threshold.

In a further possible implementation form of the first aspect, the controller is configured to determine actual engine turbocharging effectiveness as a function of the sensed scavenging gas pressure and/or the sensed exhaust gas temperature. The term “engine turbocharging effectiveness” refers to the turbocharging effectiveness as experienced/felt by the engine, independent of ambient conditions.

In a further possible implementation form of the first aspect, the controller is configured to limit the amount of bypassed pressurized gas supplied to the consumer as a function of the determined actual engine turbocharging effectiveness.

In a further possible implementation form of the first aspect, the controller is configured to determine the actual available effectiveness excess of the one or more turbochargers compared to a predetermined minimum engine turbocharging effectiveness threshold.

; DK 181374 B1

In a further possible implementation form of the first aspect, the controller is configured to limit the amount of bypassed pressurized gas supplied to the consumer as a function of the determined available effectiveness of the one or more turbochargers.

In a further possible implementation form of the first aspect, the controller unit is configured to adjust the amount of bypassed pressurized gas supplied to the consumer to the need for pressurized gas of the consumer of pressurized gas, preferably, in response to a signal from the consumer of pressurized gas, preferably while avoiding exceeding thresholds.

In a further possible implementation form of the first aspect, the one or more turbocharges have, at least in a given engine load range, a turbocharger effectiveness that exceeds a predetermined minimum required engine turbocharging effectiveness.

In a further possible implementation form of the first aspect, the one or more turbochargers have a turbine with a variable geometry turbine allowing adjustment of the turbine flow area, the control unit being coupled to the one or more turbocharges for controlling the variable geometry of the turbine and the control unit being configured to adjust the geometry of the turbine to maximize the pressure delivered by the compressor under the actual the operating conditions of the engine, preferably by reducing the turbine flow area.

In a further possible implementation form of the first aspect, the engine comprises two or more turbochargers, wherein the controller unit is configured to cut-out one

. DK 181374 B1 or more of the two or more the turbochargers, to maximize the pressure delivered by the compressor under partial load conditions of the engine, the control unit being preferably configured to cut-out one or more of the two or more turbochargers as a function of the engine load.

In a further possible implementation form of the first aspect, a switch point for cutting out one or more of the two or more turbochargers is placed in the range of 60 to 80 % engine load, and the controller is configured to cut out one or more of the two or more turbochargers when the engine load is below the switch point. Additional turbocharges can be added similarly.

In a further possible implementation form of the first aspect, the controller is operably coupled to a first electronic control valve for controlling the amount of scavenging gas taken from the intake system and/or operably coupled to a second electronic control valve for controlling the amount of exhaust gas taken from the exhaust system.

In a further possible implementation form of the first aspect, partial engine load covers a range from 20 to 80% of the maximum continuous rating of the engine.

In a further possible implementation form of the first aspect, the controller is configured to reduce the amount of bypassed pressurized gas supplied to the consumer when the sensed scavenging gas pressure is below a scavenging gas pressure threshold, the scavenge gas pressure threshold preferably being adjusted according to ambient conditions.

; DK 181374 B1

In a further possible implementation form of the first aspect, the controller is configured to reduce the amount of bypassed pressurized gas supplied to the consumer when the sensed exhaust gas temperature is above an exhaust gas temperature threshold, the exhaust gas temperature threshold preferably being adjusted according to ambient conditions.

In a further possible implementation form of the first aspect, partial engine load covers a range from 20 to 800% of the maximum continuous rating of the engine inventors is this a correct indication of the range, in particular in connection with turbocharger cutout, should the upper range.

In a further possible implementation form of the first aspect, the engine comprises a pressure sensor for sensing the scavenging gas pressure in the intake system, preferably the pressure in the scavenge air receiver or just upstream of the scavenge air receiver and/or a temperature sensor in the exhaust system for sensing the exhaust gas temperature in the exhaust system, preferably in the exhaust gas receiver or just downstream of the exhaust gas receiver and/or an observer for estimating the scavenging pressure in the intake system, preferably the pressure in the scavenge air receiver or just upstream of the scavenge air receiver and/or an observer for estimating the temperature in the exhaust system, preferably in the exhaust gas receiver or just downstream of the exhaust gas receiver.

According to a second aspect, there is provided a method of operating a large turbocharged two-stroke internal combustion engine of the uniflow type, for suppling i DK 181374 B1 pressurized scavenging gas and/or exhaust gas from the engine to a consumer of pressurized gas, the engine comprising:

a plurality of cylinders with scavenge ports at their lower end and an exhaust valve at their upper end,

an intake system through which scavenging gas is introduced into the cylinders, the intake system comprising a scavenge gas receiver connected to the cylinders via the scavenge ports,

an exhaust system through which exhaust gas produced in the cylinders is exhausted, the exhaust system comprising an exhaust gas receiver connected to the cylinders via the exhaust valves, one or more turbochargers, the one or more turbochargers having an exhaust gas-driven turbine operably coupled to a compressor, with an inlet of the turbine connected to the exhaust system and an outlet of the compressor connected to the intake system for delivering a flow of pressurized scavenge gas to the intake system,

a bypass system for supplying bypassed pressurized gas to the consumer of pressurized gas, bypassing a controlled amount of scavenging gas from the intake system or a controlled amount of pressurized exhaust gas from the exhaust, and maximizing scavenging gas pressure and/or maximizing scavenging gas bypass mass-flow by one or more of:

- increasing the speed of an auxiliary blower in the intake system of the engine, - increasing the speed of an EGR blower in an EGR installation of the engine,

- opening a cylinder bypass valve in a cylinder bypass installation of the engine,

DK 181374 B1 - opening an exhaust gas bypass to a power turbine installation of the engine for driving a dedicated electrically driven compressor, - adjusting the geometry and thereby the turbine flow area of a variable geometry turbine to maximize the pressure delivered by the compressor under the actual operating conditions of the engine, preferably by reducing the turbine flow area, - cutting-out one or more of the one or more turbochargers, to maximize the pressure delivered by the compressor under partial load conditions of the engine, preferably as a function of the engine load, - activating one turbocharger below a first cutout engine load threshold, activating two turbochargers in an interval between the first cutout engine load threshold and a second cutout engine load threshold, and activating three turbochargers above the second cutout engine load threshold.

In a possible implementation form of the second aspect, the method comprises sensing the scavenging gas pressure in the intake system, preferably the pressure in the scavenge alr receiver or just upstream of the scavenge alr receiver and/or sensing the exhaust gas temperature in the exhaust system, preferably in the exhaust gas receiver or just downstream of the exhaust gas receiver and adjusting the amount of bypassed pressurized gas supplied to said consumer as a function of the sensed scavenging gas pressure and/or exhaust gas temperature.

In a possible implementation form of the second aspect, the method comprises estimating the scavenging gas pressure in the intake system, preferably the pressure in the scavenge air receiver or just upstream of the i. DK 181374 B1 scavenge air receiver, and/or estimating the exhaust gas temperature in the exhaust system, preferably in the exhaust gas receiver or just downstream of the exhaust gas receiver and adjusting the amount of bypassed pressurized gas supplied to said consumer as a function of the sensed scavenging gas pressure and/or exhaust gas temperature.

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

BRIEF DESCRIPTION OF THE DRAWINGS

In the following detailed portion of the present disclosure, the invention will be explained in more detail with reference to the example embodiments shown in the drawings, in which:

Fig. 1 is an elevated front view of a large two-stroke internal combustion engine according to an example embodiment.

Fig. 2 is an elevated side view of the large two-stroke internal combustion engine of Fig. 1.

Fig. 3 is a diagrammatic representation of the large two- stroke internal combustion engine according to Fig. 1.

Fig. 4 is a diagrammatic representation of an embodiment of the large two-stroke internal combustion engine with a plurality of turbochargers configured for turbocharger cut- out, and

Fig. 5 is a diagrammatic representation of an embodiment of the large two-stroke internal combustion engine with a variable geometry turbocharger.

i. DK 181374 B1

DETAILED DESCRIPTION

Figs. 1, 2, and 3 show a large low-speed turbocharged two- stroke diesel engine 100 with a crankshaft 8 and crossheads 9. Fig. 3 shows a diagrammatic representation of a large low-speed turbocharged two-stroke diesel engine with its intake and exhaust systems. In this example embodiment, the engine 100 has six cylinders 1 in line. Large low-speed turbocharged two-stroke diesel engines have typically between four and fourteen cylinders 1 in line, carried by a cylinder frame 23 that is carried by an engine frame 11.

The engine 100 may e.g. be used as the main engine in a marine vessel or as a stationary engine for operating a generator in a power station. The total output of the engine 100 may, for example, range from 1,000 to 110,000 kW.

The engine 100 is in this example embodiment a compression- ignited engine 100 of the two-stroke uniflow type with scavenging ports 18 at the lower region of the cylinder liners 1 and a central exhaust valve 4 at the top of each cylinder liner 1. However, it is understood that the engine 100 does not need to be compression ignited but can alternatively be spark ignited. Hence, in the present embodiment, the compression pressure of the engine 100 will be sufficiently high for compression ignition, but it is understood that the engine 100 can operate with lower compression pressure and be ignited by spark or similar means.

The intake system of the engine 100 comprises a scavenge air receiver 2. The scavenge air is passed from the scavenge air receiver 2 to the scavenge ports 18 of the individual cylinders 1. A piston 10 that reciprocates in the cylinder liner 1 between the bottom dead center (BDC) and top dead center (TDC) compresses the scavenge air. Fuel is injected y DK 181374 B1 through fuel valves 55 that are arranged in the cylinder cover 22. Combustion follows, and exhaust gas is generated.

An exhaust valve 4 is centrally arranged in the cylinder cover 22 with a plurality of fuel valves 55 is distributed around the central exhaust valve 4. The exhaust valve 4 is actuated by an electrohydraulic exhaust valve actuation system (not shown) that is controlled by a controller 50.

The fuel valves 55 are part of the fuel supply system. The controller 50 is also configured to control the operation of the fuel valves 55.

When an exhaust valve 4 is opened, the exhaust gas flows through an exhaust system that includes an exhaust duct associated with the cylinders 1 into the exhaust gas receiver 3 and onwards through a first exhaust conduit 19 to a turbine 8 of a turbocharger 5 (in an embodiment, the engine 100 is provided with a plurality of turbochargers 5), from which the exhaust gas flows away through a second exhaust conduit via an economizer 20 to an outlet 21 and into the atmosphere.

Through a shaft, the turbine 8 drives a compressor 7 supplied with fresh air via an air inlet 12. The compressor 7 delivers pressurized scavenge air to a scavenge air conduit 13 leading to the scavenge air receiver 2. The scavenge air in the scavenge air conduit 13 passes an intercooler 14 for cooling the scavenge air.

The cooled scavenge air passes via an auxiliary blower 16 driven by an electric motor 17 that pressurizes the scavenge air flow when the compressor 7 of the turbocharger 5 does not deliver sufficient pressure for the scavenge air receiver 2, i.e. in low or partial load conditions of the

. DK 181374 B1 engine 100. At higher engine loads the turbocharger compressor 7 delivers sufficient compressed scavenge air and then the stopped auxiliary blower 16 is passed via a non-return valve 15.

With reference to the embodiments of Figs. 4 and 5 the large marine engine 100, i.e. a large turbocharged two- stroke internal combustion engine 100 of the uniflow type is configured to supply pressurized scavenging gas and/or exhaust gas to a consumer of pressurized gas 200. In this embodiment, structures and features that are the same or similar to corresponding structures and features previously described or shown herein are denoted by the same reference numeral as previously used for simplicity. The consumer of pressurized gas 200 can for example be an air lubrication system of a marine vessel in which the large marine engine 100 is installed for reducing the resistance of the marine vessel when moving through the water.

Scavenging gas is introduced into the cylinders 1 through the intake system, the intake system comprising the scavenge gas receiver 2 connected to the cylinders (1) via the scavenge ports 18.

Exhaust gas produced in the cylinders is exhausted through the exhaust system, the exhaust system comprising the exhaust gas receiver 3 connected to the cylinders 1 via the exhaust valves 4,

A bypass system supplies bypassed pressurized gas to the consumer of pressurized gas 200 by taking out a controlled amount of scavenging gas from the intake system thereby bypassing the engine 100. Hereto, a first bypass conduit 43 connects to the intake system, at a position downstream

Cc DK 181374 B1 of the outlet of the compressor 7, for example as shown at a position on the scavenge air receiver 2. The first bypass conduit or the 3 comprises in an embodiment a first bypass control valve 41 and connects to the consumer of pressurized gas 200. In an embodiment, the first bypass conduit 43 includes a first bypass blower 47 (compressor or pneumatic pump). The first bypass blower 47 is activated when the amount of pressurized gas supplied by the engine 100 without the support of the first bypass blower 47 is insufficient to meet the demand of the consumer of pressurized gas 200. Preferably, both or either the first bypass control valve 41 and the first bypass blower 47 are controlled by the controller 50. A bypass conduit comprising a first nonreturn valve 45 allows bypassing of the first bypass blower 47 when support by the first bypass blower 47 is not required. A pressure sensor 34 for sensing the pressure in the intake system downstream of the compressor 7 is arranged in the intake system and the signal from the pressure sensor 34 is communicated to the controller 50, for example by a signal line. The pressure sensor 34 may also be located in the scavenge air receiver 2, or just upstream thereof. Alternatively, an observer (not shown in Figs., can in an embodiment be part of the controller 50) that estimates the pressure in the intake system, for example, the pressure in the scavenger receiver can be used to determine the pressure for use by the controller 50.

Alternatively, or in combination, the bypass system takes out a controlled amount of pressurized exhaust gas from the exhaust system thereby bypassing the turbine. Hereto, a second bypass conduit 49 connects to the exhaust system, at a position upstream of the inlet of the turbine 8, for example as shown at a position on the exhaust air receiver

- DK 181374 B1 3. The second bypass conduit 49 comprises in an embodiment a second bypass control valve 42 and connects to the consumer of pressurized gas 200. In an embodiment, the second bypass conduit 49 includes a second bypass blower 46 (compressor or pneumatic pump). The first bypass blower 47 is activated when the amount of pressurized gas supplied by the engine 100 without the support of the first bypass blower 47 is insufficient to meet the demand of the consumer of pressurized gas 200. A bypass conduit comprising a second nonreturn valve 44 allows bypassing of the second bypass blower 46 when support by the second bypass blower 46 1s not required Preferably, both or either the second bypass control valve 42 and the second bypass blower 46 are controlled by the controller 50. A temperature sensor 33 for sensing the pressure in the exhaust system upstream of the turbine 8 is arranged in the exhaust system and the 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 such that it senses the temperature in the exhaust gas receiver 3, or just downstream of the exhaust gas receiver 3. Alternatively, an observer (not shown in the Figs., can in an embodiment be part of the controller 50) configured to estimate the temperature in the exhaust gas may be used to determine the exhaust gas temperature for use by the controller 50.

The controller 50, is configured to apply the mentioned tuning measures to maximize the scavenging pressure supplied by the turbine or turbines 7 of the turbocharging system 5.

The controller 50 is configured to adjust the amount of bypassed pressurized gas supplied to the consumer 200 as a

DK 181374 B1 function of the sensed or observed scavenging gas pressure and/or exhaust gas temperature, in particular for limiting the amount of bypassed pressurized gas when tuning measures have been applied and the scavenging pressure being below a threshold and/or the exhaust gas temperature being above a threshold.

Accordingly, the controller 50 is configured to limit the amount of bypassed pressurized gas supplied to the consumer of pressurized gas 200 when the sensed scavenging pressure is below a scavenging pressure threshold and/or the sensed exhaust gas temperature is above an exhaust gas temperature threshold.

In an embodiment, the controller 50 is configured to determine actual engine turbocharging effectiveness as a function of the sensed scavenging gas pressure and/or the sensed exhaust gas temperature and to limit the amount of bypassed pressurized gas supplied to the consumer of pressurized gas 200 as a function of the determined actual engine turbocharging effectiveness. Preferably, the controller 50 is configured to limit the amount of bypassed pressurized gas supplied to the consumer of pressurized gas 200 when the determined actual engine turbocharging effectiveness is below an actual engine turbocharging effectiveness threshold.

The controller 50 is preferably configured to determine the actual available effectiveness excess of the one or more turbochargers 5 compared to a predetermined minimum engine turbocharging effectiveness threshold and also configured to limit the amount of bypassed pressurized gas supplied to the consumer of pressurized gas 200 as a function of the

0 DK 181374 B1 determined available effectiveness excess of the one or more turbochargers 5.

In an embodiment, the controller 50 is configured to adjust the amount of bypassed pressurized gas supplied to the consumer 200 to the need for pressurized gas of the consumer of pressurized gas 200, preferably, in response to a signal from the consumer of pressurized gas 200 as long as the determined available effectiveness excess is not exceeded.

Preferably, the one or more turbocharges 5 have, at least in a given engine load range, a turbocharger effectiveness that exceeds a predetermined minimum required engine turbocharging effectiveness.

In the embodiment shown in Fig. 5, the one or more turbochargers 5 have a turbine 5 with a variable geometry turbine 8 allowing adjustment of the turbine flow area. The controller 50 is coupled to the one or more turbocharges 5 for controlling the variable geometry of the turbine 8 and the control unit 50 is configured to adjust the geometry of the turbine 8 to maximize the pressure delivered by the compressor 7 under the actual operating conditions of the engine 100 (as sensed by the controller 50), preferably by reducing the turbine flow area.

In the embodiment of Fig. 4 the engine 100 comprises two or more turbochargers 5 and the controller 50 is configured to cut-out one or more of the two or more turbochargers 5, to maximize the pressure delivered by the compressor(s) 7 under partial load conditions of the engine 100. The control unit 50 is preferably configured to cut-out one or more of the two or more turbochargers 5 as a function of the engine load.

>0 DK 181374 B1

A switch point for cutting out one or more of the two or more turbochargers 5 is placed in the range of 60 to 80 % engine load, and the controller 50 is configured to cut out one or more of the two or more turbochargers 5 when the engine load is below the switch point. The switch point for turbocharger cut-out can be optimized (shifted to higher engine load) by using different installation parts or different frame sizes for the turbochargers 5.

In an embodiment (not shown) the engine 100 comprises more than two turbochargers 5 and the controller 50 is configured to activate one turbocharger 5 below a first cutout engine load threshold so that only one turbocharger 5 with a suitable flow area is running at low engine load.

The controller 50 is further configured to activate two turbochargers 5 in an interval between the first cutout engine load threshold and a second cutout engine load threshold so that the combination of the flow area of the active turbochargers 5 is suitable running at medium engine load, and to activate three turbochargers 5 above the second cutout engine load threshold, so that the combined flow area of the active turbochargers 5 matches the operating conditions. A first control valve 35 is provided to selectively connect the turbine 8 of the turbocharger 5 on the left side of Fig. 4 from the exhaust gas receiver 3 and a second control valve 36 1s provided to selectively connect the compressor 7 of the turbocharger 5 on left side of Fig. 4 from the scavenge air receiver 2. The activate in sequence can be optimized by using turbochargers 5 with different flow areas, and 1s not limited to three turbochargers 5, there could be 4 or more turbochargers 5.

The engine operation can be optimized by switching the turbochargers 5 on and off in a particular sequence so that

> DK 181374 B1 only the turbocharger 5 or combination of turbocharges 5 with the most suitable flow area is running at a given load. For example, with increasing load, turbochargers 3 are separately switched on in order to increase the total turbocharger flow area step by step until close to maximum engine load all turbochargers are active.

The controller 50 is operably coupled to the first electronic control valve 41 for controlling the amount of scavenge gas taken from the intake system and/or operably coupled to the second electronic control valve 42 for controlling the amount of exhaust gas taken from the exhaust system.

The controller 50 is in an embodiment configured to reduce the amount of bypassed pressurized gas supplied to the consumer 200 when the sensed scavenging gas pressure is below a scavenging gas pressure threshold. The scavenge gas pressure threshold is preferably adjusted according to ambient conditions, with the lowest threshold being applied in Arctic conditions and the highest scavenge gas pressure threshold being applied in tropical conditions. The appropriate level for the scavenging gas pressure threshold and adjustment of the scavenging gas pressure threshold is an embodiment based on tests or simulations of the engine 100.

The controller 50 is in an embodiment configured to reduce the amount of bypassed pressurized gas supplied to the consumer 200 when the sensed exhaust gas temperature is above an exhaust gas temperature threshold. The exhaust gas temperature threshold is preferably adjusted according to ambient conditions, with the lowest exhaust gas temperature threshold being applied in Arctic conditions and the

> DK 181374 B1 highest threshold being applied in tropical conditions.

The appropriate level for the exhaust gas temperature threshold and adjustment of the exhaust gas temperature threshold is an embodiment based on tests or simulation of the engine 100.

In the embodiment of Fig. 5 the engine 100 comprises a turbocharger 5 with variable turbine geometry 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 compressor 7 under the actual operating conditions of the engine 100, preferably by reducing the turbine flow area of all of the turbochargers 5, to maximize the pressure delivered by the compressor (s) 7 under partial load conditions of the engine 100. In this embodiment, the engine 100 is provided with an optional

Exhaust Gas Recirculation (EGR) system that comprises an

EGR unit 60, an EGR blower 29 and and 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 comprises elements for treating the recirculated exhaust gas such as an EGR cooler 62 and/or a scrubber and water mist catcher 63.

The controller 50 is in an embodiment configured to operate the engine 100 in a way to maximize scavenging gas pressure and/or maximize scavenging gas bypass mass-flow by controlling a PTI (Power Take In) functionality of a THS (Turbo Hydraulic System) installation on the one or more turbochargers 5.

In another embodiment, the controller 50 is configured to operate the engine 100 in a way to maximize scavenging gas pressure and/or maximize scavenging gas bypass mass-flow

> DK 181374 B1 by controlling the auxiliary blower installation 16 for additional pressurization at higher loads than usual.

In another embodiment, the controller 50 is configured to operate the engine 100 in a way to maximize scavenging gas pressure and/or maximize scavenging gas bypass mass-flow by using the high turbocharging effectivity of a two-stage turbocharger installation.

In another embodiment, the controller 50 is configured to operate the engine 100 in a way to maximize scavenging gas pressure by controlling the cylinder bypass valve installation for pressurization.

In another embodiment, the controller 50 is configured to operate the engine 100 in a way to maximize exhaust gas bypass pressure by controlling the functionality of an EGR blower 29 in an EGR installation on a Tier 3 EGR engine 100 for additional pressurization in Tier 2 mode.

In another embodiment, the controller 50 is configured to operate the engine 100 in a way to maximize the delivered gas pressure by controlling an additional small turbocharger installation for pressurization of additional ambient air or bypassed scavenge air.

In another embodiment, the controller 50 is configured to operate the engine 100 in a way to maximize the delivered gas pressure by controlling an exhaust gas bypass to a power turbine installation for driving a dedicated additional electrically driven compressor. The gas compressed by the electrically driven compressor is added to the bypass mass flow.

> DK 181374 B1

In another embodiment, the controller 50 is configured to operate the engine 100 in a way to maximize the delivered gas pressure and/or mass-flow by controlling a hydraulically driven compressor powered by the engine/'s hydraulic pressure system installation.

The engine 100 is operated in accordance with a method that comprises bypassing a controlled amount of scavenging gas from the intake system or a controlled amount of pressurized exhaust gas from the exhaust. The scavenging gas pressure in the intake system is sensed and/or the exhaust gas temperature in the exhaust system is sensed.

The amount of bypassed pressurized gas supplied to the consumer 200 is adjusted as a function of the sensed scavenging gas pressure and/or exhaust gas temperature.

The various measures to optimize the performance of the engine 1llustrated in the embodiments above can be combined, e.g. by combining sequential turbocharging (turbocharged cut out) with adjustment of the turbine flow area of one or more variable geometry turbocharges.

The method and engine have been described in conjunction with various embodiments herein. However, other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, 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 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

DK 181374 B1 25 combination of these measured cannot be used to advantage.

The reference signs used in the claims shall not be construed as limiting the scope.

Claims

Je DK 181374 B1 PATENT CLAIM

1. A longitudinally scavenged type large turbocharged two-stroke internal combustion engine (100) configured to supply pressurized scavenging gas and/or exhaust gas to a pressurized gas consumer (200), the engine (100) comprising: a plurality of cylinders (1 ) with purge ports (18) at their lower end and an exhaust valve (4) at their upper end, an intake system through which purge gas is introduced into the cylinders (1), which intake system comprises a purge gas receiver (2) connected to the cylinders (1) via the scavenging ports (18), an exhaust system through which exhaust gas produced in the cylinders is discharged, which exhaust system comprises an exhaust gas receiver (3) connected to the cylinders (1) via the exhaust valves (4), one or more turbochargers (5), where each turbocharger (5) has an exhaust gas driven turbine (8) operatively coupled to a compressor (7), with an inlet to the turbine (8) connected to the exhaust system and an outlet from the compressor (7) connected to the intake system for providing a flow of pressurized scavenging gas for the intake system, a fuel system for supplying fuel to the cylinders (1),

>; DK 181374 B1 a diversion system for the supply of diverted compressed gas to the consumer of compressed gas (200) by extracting a controlled quantity of flushing gas from the intake system, whereby it is routed around the engine (100), and/or by extracting a controlled quantity of exhaust gas under pressure from the exhaust system, whereby the turbine (8) is bypassed, and a control unit (50) coupled to a pressure sensor (34) for recording purge gas pressure and/or a temperature sensor

(33) for sensing exhaust gas temperature, wherein the control unit (50) is configured to adjust the amount of diverted pressurized gas supplied to the consumer (200) as a function of the sensed purge gas pressure and/or exhaust gas temperature,

wherein the controller (50) is configured to operate the motor (100) in a manner to maximize purge gas pressure and/or maximize purge gas bypass mass flow by one or more of:

- increasing the speed of an auxiliary fan (16) in the engine

(100) intake system,

- increasing the speed of an EGR fan (29) in an EGR installation in the engine (100),

- opening a cylinder bypass valve in a cylinder bypass installation in the engine (100),

= opening an exhaust gas bypass to a power turbine installation in the engine (100) to drive a dedicated electrically driven compressor,

- adjusting the geometry and thus the turbine flow range of a variable geometry turbine (8) of the one or more turbochargers (5) to maximize the pressure delivered by the compressor (7) under the current operating conditions of the engine (100), preferably by reducing the turbine flow range,

Je DK 181374 B1 - disconnection of one or more of the one or more turbochargers (5) to maximize the pressure delivered by the compressor (7) under partial load conditions of the engine (100), preferably as a function of the engine load, - activation of one turbocharger (5) below a first cutoff engine load threshold, activation of two turbochargers (5) in an interval between the first cutoff engine load threshold and a second cutoff engine load threshold, and activation of three turbochargers (5) above the second cutoff engine load threshold.

2. Engine (100) according to claim 1, wherein the control unit (50) is configured to limit the amount of diverted compressed gas supplied to the consumer of compressed gas (200) when a registered or observed flushing pressure is below a flushing pressure threshold, and/or the recorded or observed exhaust gas temperature is above an exhaust gas temperature threshold.

The engine (100) of claim 2, wherein the controller (50) is configured to determine current engine turbocharging efficiency as a function of the sensed or observed scavenge gas pressure and/or the sensed or observed exhaust gas temperature.

The engine (100) of claim 3, wherein the control unit (50) is configured to limit the amount of diverted compressed gas supplied to the consumer of compressed gas (200) as a function of the determined current engine turbocharging efficiency, the control unit (50) preferably being configured to reduce or limit the amount of diverted compressed gas supplied to the consumer of compressed gas (200) when the determined, current

> DK 181374 B1 engine turbocharge efficiency is below a current engine turbocharge efficiency threshold.

An engine (100) according to any one of claims 1 to 4, wherein the control unit (50) is configured to determine the current available efficiency surplus of the one or more turbochargers (5) compared to a predetermined minimum engine turbocharging efficiency threshold.

Engine (100) according to claim 5, wherein the control unit (50) is configured to limit the amount of diverted compressed gas supplied to the consumer of compressed gas (200) as a function of the determined, available efficiency surplus for the one or more turbochargers (5).

7. Engine (100) according to any one of claims 1 to 6, wherein the control unit (50) is configured to adjust the amount of diverted compressed gas supplied to the consumer of compressed gas (200) according to the need for compressed gas of the consumer of compressed gas (200), preferably in response to a signal from the consumer of compressed gas (200).

An engine (100) according to any one of claims 1 to 7, wherein the one or more turbochargers (5) have, at least in a given engine load range, a turbocharger efficiency exceeding a predetermined required minimum engine turbocharge efficiency.

9. An engine (100) according to any one of claims 1 to 10, wherein a switching point for disconnecting one or more of the two or more turbochargers (5) is in the range of 60 to 80 2 engine load, and the control unit (50 ) is configured to disconnect one or

DK 181374 B1 several of the two or more turbochargers (5) when the engine load is below the switching point.

10. Engine (100) according to any one of claims 1 to 11, wherein the control unit (50) is operatively coupled to a first electronic control valve (41) for controlling the amount of purge gas taken from the intake system and/or operatively coupled to another electronic control valve (42) for controlling the amount of exhaust gas taken from the exhaust system.

Engine (100) according to any one of claims 1 to 10, wherein the control unit (50) is configured to reduce the amount of diverted pressurized gas supplied to the consumer (200) when the detected purge gas pressure is below a purge gas pressure threshold, which purge gas pressure threshold is preferably adjusted according to ambient conditions.

An engine (100) according to any one of claims 1 to 11, wherein the control unit (50) is configured to reduce the amount of diverted compressed gas supplied to the consumer (200) when the detected exhaust gas temperature is above an exhaust gas temperature threshold, which exhaust gas temperature threshold is preferably adjusted according to ambient conditions.

13. Engine (100) according to any one of claims 1 to 12 comprising a pressure sensor (34) for recording the purge gas pressure in the intake system, preferably the pressure in the purge gas receiver (2) or just upstream of the purge gas receiver (2) and/or a temperature sensor ( 33) in the exhaust system for recording the exhaust gas temperature in the exhaust system, preferably 1 the exhaust gas receiver (3) or just

51 DK 181374 B1 downstream of the exhaust gas receiver (3) and/or an observer for estimating the purge pressure in the intake system, preferably the pressure in the purge gas receiver (2) or directly upstream of the purge gas receiver (2) and/or an observer for estimating the temperature in the exhaust system, preferably 1 the exhaust gas receiver (3) or just downstream of the exhaust gas receiver (3).

14. Method for operating a large, turbocharged two-stroke internal combustion engine (100) of the longitudinal scavenging type for supplying pressurized scavenging gas and/or exhaust gas from the engine (100) to a consumer of compressed gas (200), the engine (100) comprising: a plurality of cylinders (1) with purge ports (18) at their lower end and an exhaust valve (4) at their upper end, an intake system through which purge gas is introduced into the cylinders (1), which intake system comprises a purge gas receiver (2) connected with the cylinders (1) via the scavenging ports (18), an exhaust system through which exhaust gas produced in the cylinders is discharged, which exhaust system comprises an exhaust gas receiver (3) connected to the cylinders (1) via the exhaust valves (4), one or more turbochargers ( 5), which one or more turbochargers (5) has an exhaust gas driven turbine (8) operatively coupled to a compressor (7), with an inlet to the turbine (8) connected to the exhaust system and an outlet from the compressor (7) connected with

> DK 181374 B1 the intake system for supplying a stream of purge gas under pressure to the intake system,

a diversion system for supplying diverted compressed gas to the consumer of compressed gas (200),

diverting a controlled amount of purge gas from the intake system or a controlled amount of pressurized exhaust gas from the exhaust, and maximizing purge gas pressure and/or maximizing purge gas bypass mass flow by one or more of:

- increasing the speed of an auxiliary fan (16) in the engine's (100) intake system,

- opening an exhaust gas bypass to a power turbine installation in the engine (100) to drive a dedicated electrically driven compressor,

- adjusting the geometry and thus the turbine flow range of a variable geometry turbine (8) to maximize the pressure delivered by the compressor (7) under the actual operating conditions of the engine (100), preferably by reducing the turbine flow range,

- disconnecting one or more of the one or more turbochargers (5) to maximize the pressure delivered by the compressor (7) under partial load conditions of the engine (100), preferably as a function of engine load,

- activation of one turbocharger (5) below a first cut-off engine load threshold, activation of two turbochargers (5) in an interval between the first cut-off engine load threshold and a second cut-off engine load threshold and activation of three

> DK 181374 B1 turbochargers (5) above the second cut-off engine load threshold.

15. Method according to claim 14 comprising recording the scavenging gas pressure in the intake system, preferably the pressure in the scavenging gas receiver (2) or just upstream of the scavenging gas receiver (2) and/or recording the exhaust gas temperature in the exhaust system, preferably 1 the exhaust gas receiver (3) or just downstream of the exhaust gas receiver (3 ) and adjusting the amount of diverted pressurized gas supplied to the consumer (200) as a function of the detected purge gas pressure and/or exhaust gas temperature.

16. Method according to claim 14 comprising estimating the scavenging gas pressure in the intake system, preferably the pressure in the scavenging gas receiver (2) or just upstream of the scavenging gas receiver (2) and/or estimating the exhaust gas temperature in the exhaust system, preferably 1 the exhaust gas receiver (3) or just downstream of the exhaust gas receiver (3 ) and adjusting the amount of diverted pressurized gas supplied to the consumer (200) as a function of the estimated purge gas pressure and/or exhaust gas temperature.