CN102242670A - Large-sized two-stroke diesel engine having exhaust gas purifying system - Google Patents

Abstract

The invention relates to a large turbocharged two-stroke internal combustion engine of the crosshead type, comprising a plurality of cylinders, each connected to an exhaust receiver. A selective catalytic reduction reactor is arranged downstream of the exhaust gas receiver. An exhaust pipe connects the outlet of the selective catalytic reduction reactor to the turbine of the turbocharger. The turbine drives the compressor of the turbocharger, which delivers the scavenging air to the scavenging air receiver via the scavenging air path. The scavenging receiver is connected to a plurality of cylinders. An auxiliary blower in the scavenging path assists the compressor during low load conditions. A controllable bypass line extends from the scavenging receiver to the exhaust. At low engine loads, a controlled scavenging flow is directed from the scavenging receiver to the exhaust pipe at a location downstream of the selective catalytic reduction reactor and upstream of the turbine of the turbocharger. This measure increases the temperature of the exhaust gas entering the selective catalytic reduction reactor.

Description

Large two-stroke diesel engine with exhaust gas purification system

technical field

The present invention relates to a large crosshead turbocharged two-stroke internal combustion piston engine, preferably a diesel engine with an exhaust gas purification system, especially a crosshead large two-stroke crosshead with a selective catalytic reduction reactor Diesel engines.

Background technique

Large two-stroke engines of the crosshead type are commonly used in the propulsion systems of large ships or as prime movers in power plants. Emissions demands have been and will be more difficult to meet, especially with regard to the level of mono-nitrogen oxides (NO _x ).

The use of selective catalytic reduction (SCR) reactors is a known measure for assisting diesel engines in reducing _NOx emissions. A minimum temperature of about 300 to 350° C. for the exhaust gas entering the SCR converter is required for proper operation of the SCR reactor.

However, due to the nature of two-stroke turbocharged engines, the exhaust gas temperature at low engine loads (eg below 40% of the maximum continuous power associated with the engine) is relatively low, i.e. too low for the exhaust gas to operate in the SCR converted in the reactor.

Under the aforementioned low load conditions, it is difficult to maintain sufficient scavenging pressure in large turbocharged two-stroke diesel engines. Therefore, an auxiliary blower is used to maintain scavenging pressure under such low load conditions. Thus, any means taken to increase the temperature of the exhaust gas at the inlet of the SCR reactor should not negatively affect the scavenging pressure.

Therefore, there is a need for a turbocharged two-stroke diesel engine that overcomes, or at least reduces, the above-mentioned drawbacks.

Contents of the invention

In this context, it is an object of the present invention to provide a large turbocharged two-stroke diesel engine capable of operating with an SCR reactor over a wide range of engine load conditions.

The above objects are achieved by providing a crosshead type large turbocharged two-stroke internal combustion engine comprising: a plurality of cylinders each connected to an exhaust receiver; a selective catalytic reduction reactor the inlet of which is connected to the exhaust receiver the outlet of the SCR reactor; the exhaust pipe, which connects the outlet of the selective catalytic reduction reactor to the turbine of the turbocharger; The scavenging air path is sent to the scavenging air receiver; the auxiliary blower, which is in the scavenging air path, is used to assist the compressor under low load conditions; the scavenging air receiver is connected to each cylinder in the plurality of cylinders; A control bypass line extending from a location in the scavenging path downstream of the auxiliary blower or from the scavenging receiver to a location in the exhaust pipe between the outlet of the selective catalytic reduction reactor and the inlet of the turbine a position between; an electronic control unit, operatively connected to the bypass line, the electronic control unit configured to when the engine load is below a preset threshold or when the temperature of the exhaust gas entering the selective catalytic reduction reactor is low At a given threshold, the scavenging flow is allowed to flow from the scavenging receiver to the exhaust via a controllable bypass line.

At low loads, a controlled scavenging flow is directed from the scavenging receiver to the exhaust pipe at a location downstream of the selective catalytic reduction reactor and upstream of the turbine in the turbocharger. This measure increases the temperature of the exhaust gas entering the selective catalytic reduction reactor without negatively affecting the scavenging pressure.

The exhaust pipe may include a three-port mixing point for mixing bypassed scavenging gas with exhaust gas.

The bypass line may include a valve for controlling the flow of purge gas through the bypass line.

The valve may be an on-off type electric control valve controlled by the electric control unit 33 in an open loop circuit.

Alternatively, the valve may be a proportional type electronically controlled valve controlled by an electronic control unit in a closed loop.

The engine may also include a temperature sensor proximate to the inlet of the selective catalytic reduction reactor.

The engine can be configured such that the scavenge air cooler can be deactivated via the electronic control unit.

The electronic control unit may be configured to open the bypass line as a first measure and deactivate the scavenge air cooler as a second measure.

The engine can be configured such that the scavenge air cooler can be converted into a heater by the electronic control unit.

The engine may be configured such that the electronic control unit is configured to convert the scavenge air cooler to a heater as a third measure.

The object of the present invention can also be achieved by providing a crosshead type large turbocharged two-stroke internal combustion engine comprising: a plurality of cylinders, each connected to an exhaust receiver; a selective catalytic reduction reactor, the inlet of which is connected to to the outlet of the exhaust gas receiver; the exhaust pipe which connects the outlet of the selective catalytic reduction reactor to the turbine in the turbocharger; the compressor of the turbocharger is driven by the turbine, which will scavenge the to the scavenging receiver via a scavenging path including a scavenging cooler; an auxiliary blower in the scavenging path to assist the compressor under low load conditions; the scavenging receiver is connected to the cylinders each cylinder; an electronic control unit configured to reduce or deactivate the scavenging air cooler when the engine load is less than a given threshold or when the temperature of the exhaust gas entering the selective catalytic reduction reactor is lower than a given threshold cooling function.

The engine may also include a scavenge gas bypass line for bypassing the scavenge gas cooler.

The engine may also include one or more electronically controlled valves controlled by instructions from the electronic control unit for controlling the flow of scavenging air through the scavenging air bypass pipe.

The engine may further include a cooling medium supply pipe having an electrically controlled separation valve, a cooling medium return pipe, and a cooling medium bypass circuit including an electrically controlled bypass valve. The engine may also include a recirculation line and a recirculation pump. The engine may also include a heat exchanger in the recirculation pipe for heating the medium flowing through the recirculation pipe.

The engine may also include a second scavenging air cooler, wherein the electronic control unit is configured to control a cooling capacity of at least one of the scavenging air coolers.

The engine may further include a steam injection pipe connected to the scavenging path, the steam injection pipe including an electronically controlled steam injection control valve controlled by an instruction of the electronic control unit.

The engine may further include an exhaust gas injection pipe connected to the scavenging path, the exhaust gas injection pipe including an electronically controlled exhaust gas injection control valve controlled by an instruction of the electronic control unit.

The engine may also include a heater unit in the scavenging path. The heater unit can be operated with hot air as heating medium.

The engine may further include a heat exchanger in the cooling medium supply pipe for supplying heat to a medium flowing through the cooling medium supply pipe.

Further objects, features, advantages and properties of the large two-stroke internal combustion engine according to the invention will become apparent from the detailed description.

Description of drawings

In the following particular parts of the present description, the invention will be explained in more detail with reference to exemplary embodiments shown in the accompanying drawings, in which:

FIG. 1 is a diagrammatic view of an engine according to a first embodiment of the present invention;

Figure 2 shows a diagrammatic representation of a second embodiment of the invention;

Figures 3-7 illustrate further embodiments of reduced cooling utilizing scavenging; and

Figures 8-12 illustrate further embodiments of active heating utilizing scavenging.

Detailed ways

In the following detailed description, a crosshead type large turbocharged two-stroke diesel engine and a method for operating a crosshead type large turbocharged two-stroke diesel engine according to the present invention will be described through exemplary embodiments.

The structure and operation of large turbocharged two-stroke diesel engines of the crosshead type are well known and therefore require no further explanation herein. A detailed description regarding the operation of the exhaust gas purification system is provided below.

Figure 1 shows a first exemplary embodiment of a large two-stroke diesel engine 1 according to the invention. The engine 1 can be used, for example, as the main engine in an ocean-going vessel or as a stationary engine running a generator in a power station. The total output of the engine may for example be in the range of 5000 to 110000 kW.

The engine 1 is provided with a plurality of cylinders arranged side by side in a row. Each cylinder is provided with an exhaust valve associated with its cylinder head. The exhaust path can be opened and closed via the exhaust valve. The engine's crosshead connects the piston rod to the big end of the crankshaft. The exhaust elbow is connected to the exhaust receiver 6 . The exhaust gas receiver 6 is arranged in parallel with a row of cylinders. The exhaust gas receiver 6 is a large container, dimensioned especially for the characteristics of the engine, for optimum air flow, back pressure and acoustical considerations. Typically, the exhaust receiver 6 is a large hollow cylinder made of sheet steel. Due to its size and bulk, the exhaust receiver is suspended from the engine structure for vibration handling purposes.

The exhaust gas flow is led from the outlet of the exhaust gas receiver 6 via a selective catalytic reactor 8 (SCR reactor) and an exhaust pipe 10 to a turbine 12 of the turbocharger. Thus, the outlet of the exhaust gas receiver 6 is connected to the inlet of the SCR reactor 8 . The exhaust gas flows through the SCR reactor 8, which removes or at least substantially reduces the amount of NOx in the exhaust gas, converting NOx to nitrogen and oxygen. The outlet of the SCR reactor is connected to an exhaust pipe 10 which leads hot and pressurized exhaust gas to a turbine 12 . The exhaust gas is discharged into the atmosphere downstream of the turbine 12 .

The turbocharger also includes a compressor 14 driven by the turbine 12 . A compressor 14 is connected to the air inlet. Compressor 14 delivers pressurized scavenging air to scavenging air receiver 22 via scavenging air flow path 16 , which includes scavenging air cooler 18 and auxiliary blower 20 .

The scavenge air cooler 18 is operated with water as cooling medium. The scavenge air cooler 18 may be of various types. One possibility is a flat panel cooler, where the cooling medium is not in direct physical contact with the sweep air. Another possibility is a scrubber, where the cooling medium is in direct contact with the sweep air.

Auxiliary blower 20 is typically driven by an electric motor (and may also be hydraulic) and is activated at low load conditions (typically less than 40% of maximum continuous power) to maintain sufficient scavenging pressure for compressor 14 . When the auxiliary blower is not used, it is bypassed by a not shown bypass.

The scavenging receiver 22 is an elongated hollow cylinder extending along the cylinders of the engine. The scavenging air flows from the scavenging receiver 22 to the scavenging port of each cylinder.

A controllable bypass line 26 branches from the scavenging receiver 22 . The other end of the controllable bypass line 26 is connected to the exhaust pipe 10 at a three-port mixing point 30 . The mixing point 30 is located downstream of the outlet of the SCR reactor 8 and upstream of the inlet of the turbine 12 .

Alternatively, the start of the controllable bypass line 26 may be located in the scavenging duct 16 at a location downstream of the auxiliary blower 20 .

Under the instruction of the electronic control unit 33 , the electronic control valve 28 regulates the flow of the scavenging air from the scavenging air flow path 16 to the exhaust pipe 10 . In one embodiment, valve 28 is an on/off type valve controlled by electronic control unit 33 in an open loop circuit. In this embodiment, the electronic control unit 33 is configured to open the valve 28 when the engine load drops below a predetermined threshold and to close the valve 28 when the engine load rises above the predetermined threshold. These two thresholds need not be the same and can be defined as a percentage of the engine's maximum continuous power.

In another embodiment, the electronic control valve 28 is a proportional valve controlled by the electronic control unit 33 in a closed loop. Here, the controller receives information about the temperature of the exhaust gas at the inlet of the SCR reactor 8 from the temperature sensor 35 and the electronic control unit 33 is configured to control the opening degree of the valve 28 in response to the measured temperature of the exhaust gas entering the SCR reactor 8 . Therefore, when the measured temperature is lower than the minimum desired temperature, the electronic control unit 33 will increase the opening degree of the electronic control valve 28 to increase the exhaust gas temperature.

This threshold can also be controlled by the mixing temperature at the inlet of the turbine, i.e. the bypass line 26 is closed when the temperature is higher than the temperature required by the SCR reactor 8, and when the temperature is almost much lower than the temperature required by the SCR reactor 8 For many times, the bypass line 26 is open.

After presetting the mixture temperature at the turbine inlet, the on/off bypass is controlled in a similar manner to the load control described.

Fig. 2 shows a second exemplary embodiment of a large two-stroke diesel engine 1 according to the invention. The same reference numerals as in FIG. 1 refer to the same components. The embodiment according to FIG. 2 is largely identical to the embodiment of FIG. 1 with the exception of the following aspects of the scavenging air cooler 18 in the scavenging air path 16 .

A supply pipe 40 carries cold water to the scavenge air cooler 18 and a return pipe 42 carries warm water away from the scavenge air cooler 18 . In the second embodiment, the electrically controlled bypass valve 44 in the cooling medium bypass circuit 43 and the electrically controlled separation valve 46 acting on the instruction of the controller 33 enable the cold water in the supply pipe 40 not to pass through the scavenging air cooler 18 and deviated from the supply into the return pipe 42. A recirculation line 48 comprising a pump 50 and a heater (or heat exchanger) 52 ensures that water flows through the scavenge air cooler 18 when the scavenge air cooler 18 becomes a heater and effectively acts as a heat exchanger. The heater 52 is provided with a warm heating medium, such as warm water constituting the engine cooling system, and heats the medium circulating through the scavenging air cooler 18 .

In a second embodiment, the electronic control unit 33 can disable the cooler 18 by bypassing the cooling medium via the valves 44 and 46 . At the same time, the controller 33 will activate the pump 50 to ensure circulation of the medium in the scavenging air cooler 18 . Furthermore, the control unit 33 may activate the heater 52 by delivering a heating medium to the heater 52, thereby turning the scavenge air cooler 18 into a heater. The electronic control unit 33 is configured to take various measures to increase the temperature of the scavenging gas according to the need to increase the temperature of the exhaust gas entering the SCR reactor 8 .

Therefore, if it is sufficient to have some scavenging air into the exhaust pipe 10 via the controllable bypass line 26, the electronic control unit 33 will not take any further measures. However, if this first measure is not sufficient, the electronic control unit 33 will deactivate the cooling function of the scavenging air cooler 18 . If this second measure is not enough, as a third measure, the electronic control unit 33 will convert the scavenging air cooler 18 into a heater to actively heat the scavenging air.

Figure 2 shows examples of scavenging and exhaust gas temperatures at various locations in the system. These examples are for low engine load conditions, such as below 40% of the maximum continuous power associated with developed engines. Numbers without parentheses are the temperature of the scavenging gas that passes through the bypass line 26 and is heated at the scavenging gas cooler 18 . The numbers in parentheses are the temperatures when the engine is operated conventionally without passing the scavenge air through the bypass line 26 and with the scavenge air cooler 18 cooling the scavenge air. With the new measures, the temperature of the exhaust gas entering the SCR reactor 8 is 325° C., and the exhaust gas is hot enough to be converted in the SCR reactor 8 . Without the new measures, the temperature of the exhaust gas entering the SCR reactor 8 is 220° C., and the exhaust gas is not hot enough to be converted in the SCR reactor 8 .

FIG. 3 shows that the cooling medium is supplied to the scavenging air cooler 18 via the cooling medium supply line 40 and returned to the scavenging air cooler 18 via the cooling medium return line 42 .

FIGS. 4-7 illustrate various embodiments of controlled reduction of the cooling capacity of the scavenging air cooler 18 .

In FIG. 4 , the engine is provided with a scavenging gas bypass line 17 for bypassing a scavenging gas cooler 18 . The scavenging bypass pipe 17 includes an electronically controlled valve 23 for opening and closing the scavenging bypass pipe 17 under the instruction of the electronic control unit 33 . The scavenging path 16 includes another electronically controlled valve 21 for opening and closing the scavenging path 16 under the instruction of the electronic control unit 33 . Therefore, the electronic control unit 33 can control the flow of the scavenging gas passing through the scavenging gas bypass pipe 17 according to the need to increase the temperature of the scavenging gas, thereby increasing the temperature of the exhaust gas entering the SCR reactor 8 .

In FIG. 5 , the cooling medium supply pipe 40 is provided with an electrically controlled separation valve 46 and a cooling medium bypass circuit 43 which includes an electrically controlled bypass valve 44 and directly connects the cooling medium supply pipe 40 to the cooling medium. Medium return pipe 42. The electronic control unit 33 issues commands to the electronic valves 44 and 46, so as to control the degree of the cooling medium passing through the scavenging air cooler 18 (can be on/off or proportional control).

In FIG. 6 , a recirculation pipe 48 comprising a recirculation pump (controlled by the electronic control unit 33 ) is added to the embodiment shown in FIG. 5 for enabling the circulation of the cooling medium in the scavenging gas cooler 18 .

In FIG. 7 the engine is provided with an additional (second) scavenge air cooler 19 . The electronic control unit 33 is configured to control the cooling capacity of at least one of the scavenge air coolers 18, 19 as described above.

Figures 8-12 illustrate various embodiments for the controlled addition of heat to the purge gas.

In FIG. 8 , the engine is provided with a steam injection pipe 50 connected to the scavenging path 16 . The steam injection pipe 90 includes an electronically controlled steam injection control valve 92 commanded and controlled by the electronic control unit 33 . Thus, by controllably injecting steam, the scavenging temperature can be increased as desired, thereby increasing the temperature of the exhaust gas entering the SCR reactor 8 without reducing the scavenging pressure.

In FIG. 9 , the engine is provided with an exhaust gas injection pipe 60 connected to the scavenging path 16 . The exhaust gas injection pipe 60 includes an electronically controlled exhaust gas injection control valve 62 controlled by instructions from the electronic control unit 33 . Thus, by controllably injecting the exhaust gas, the scavenging temperature can be increased as desired, thereby increasing the temperature of the exhaust gas entering the SCR reactor 8 without reducing the scavenging pressure.

In FIG. 10 , the engine is provided with a heater unit 27 in the scavenging path 16 . A heating medium such as hot water or hot air is supplied to the heater unit 27 via a heating medium supply pipe 70 , and the returning heating medium is conveyed away through a heating medium return pipe 72 . The heating medium supply pipe 70 and the heating medium return pipe 72 are provided with electric control valves controlled by the electric control unit 33 . Accordingly, the temperature of the scavenging gas temperature can be increased as desired, thereby increasing the temperature of the exhaust gas entering the SCR reactor 8 without reducing the scavenging gas pressure.

The embodiment of FIG. 11 is substantially the same as that of FIG. 6 , but also includes a heat exchanger for adding heat to the medium circulating through the purge air cooler 18 .

In the embodiment of FIG. 12 , the engine is provided with a heat exchanger 80 in the cooling medium supply pipe 40 for supplying heat to the medium flowing through the cooling medium supply pipe 40 .

Although the teaching of the present application has been described in detail for the purpose of illustration, it should be understood that these details are for the purpose of illustration only, and various changes can be made thereto by those skilled in the art without departing from the scope of the teaching of the present application.

The above-described embodiments can be combined in any possible way to improve the function of the engine.

It should also be noted that there are many alternative ways of implementing the apparatus of the teachings of the present invention.

The term "comprising" used in the claims does not exclude other elements or steps. The terms "a" or "an" as used in the claims do not exclude a plurality. A single processor or other unit may fulfill the functions of several means recited in the claims.

Claims (22)

1. A crosshead type large turbocharged two-stroke internal combustion engine (1), comprising: a plurality of cylinders, each connected to an exhaust receiver (6); Selective catalytic reduction reactor (8), its inlet is connected to the outlet of described waste gas receiver (6); an exhaust pipe (10) connecting the outlet of said selective catalytic reduction reactor (8) to the turbine (12) of the turbocharger; The compressor (14) of the turbocharger is driven by the turbine (12), the compressor (14) delivers the scavenging gas to the scavenging gas via the scavenging gas path (16) including the Air receiver (22); an auxiliary blower (20) in said scavenging path (16) for assisting said compressor (14) during low load conditions; the scavenging receiver (22) is connected to each of the plurality of cylinders; a controllable bypass line (26) extending from a location in the scavenging path (16) downstream of the auxiliary blower or from the scavenging receiver (22) into the exhaust duct (10) a position between the outlet of said selective catalytic reduction reactor (8) and the inlet of said turbine (12); an electronic control unit (33) operatively connected to said bypass line (26), said electronic control unit (33) being configured to operate when the engine load is below a predetermined threshold or when entering said selective catalytic reduction reaction A scavenging gas flow from the scavenging receiver (22) is allowed to flow from the scavenging receiver (22) to the exhaust pipe (10) through the controllable bypass line (26) when the temperature of the exhaust gas from the receiver (8) is below a given threshold. 2. A crosshead type large turbocharged two-stroke internal combustion engine according to claim 1, wherein said exhaust pipe (10) comprises a three-port mixing point (30) for mixing bypassed scavenging gas with exhaust gas . 3. The crosshead type large turbocharged two-stroke internal combustion engine according to claim 1, wherein said bypass line (26) includes a valve (28) for controlling the passage of scavenging air through said bypass line (26) ) flow. 4. The crosshead type large-scale turbocharged two-stroke internal combustion engine as claimed in claim 3, wherein the valve (28) is an on-off electronically controlled valve controlled by the electronic control unit (33) in an open loop circuit. valve. 5. The crosshead type large turbocharged two-stroke internal combustion engine according to claim 3, wherein the valve (28) is a proportional electric control valve controlled by the electronic control unit (33) in a closed loop circuit. 6. The crosshead type large turbocharged two-stroke internal combustion engine according to claim 6, further comprising a temperature sensor (35) adjacent to the inlet of the selective catalytic reduction reactor (8). 7. The crosshead type large turbocharged two-stroke internal combustion engine according to claim 1, wherein said electronic control unit (33) is capable of deactivating said scavenging air cooler (18). 8. The crosshead type large turbocharged two-stroke internal combustion engine according to claim 7, wherein the electronic control unit (33) is configured to open the bypass line (26) as a first measure, and to stop The sweep air cooler (18) is used as a second measure. 9. The crosshead type large turbocharged two-stroke internal combustion engine according to claim 7, wherein the scavenging air cooler (18) can be converted into a heater by the electronic control unit (33). 10. The crosshead type large turbocharged two-stroke internal combustion engine according to claim 8, wherein the electronic control unit (33) is configured to convert the scavenging air cooler (18) into a heater as a third measure. 11. A crosshead type large turbocharged two-stroke internal combustion engine (1), comprising: a plurality of cylinders, each connected to an exhaust receiver (6); Selective catalytic reduction reactor (8), its inlet is connected to the outlet of described waste gas receiver (6); an exhaust pipe (10) connecting the outlet of said selective catalytic reduction reactor (8) to the turbine (12) of the turbocharger; The compressor (14) of the turbocharger is driven by the turbine (12), the compressor (14) delivers the scavenging gas to the scavenging gas via the scavenging gas path (16) including the Air receiver (22); an auxiliary blower (20) in said scavenging path (16) for assisting said compressor (14) during low load conditions; the scavenging receiver (22) is connected to each of the plurality of cylinders; an electronic control unit (33) configured to reduce or deactivate the sweep when the engine load is less than a given threshold or when the temperature of the exhaust gas entering the selective catalytic reduction reactor (8) is lower than a given threshold The cooling function of the air cooler (18). 12. The crosshead type large turbocharged two-stroke internal combustion engine according to claim 11, further comprising a scavenging gas bypass pipe (17) for bypassing the scavenging gas cooler (18). 13. The crosshead type large-scale turbocharged two-stroke internal combustion engine according to claim 12, further comprising one or more electronically controlled valves (23, 21) controlled by instructions of the electronic control unit (33), for The flow of scavenging gas through said scavenging gas bypass pipe (17) is controlled. 14. The crosshead type large turbocharged two-stroke internal combustion engine as claimed in claim 11, further comprising a cooling medium supply pipe (40) with an electrically controlled separation valve (46), a cooling medium return pipe (42) and an electrically controlled Coolant bypass circuit (43) for bypass valve (44). 15. The crosshead type large turbocharged two-stroke internal combustion engine according to claim 14, further comprising a recirculation pipe (48) and a recirculation pump (50). 16. The crosshead type large turbocharged two-stroke internal combustion engine as claimed in claim 15, further comprising a heat exchanger (52) in the recirculation pipe for heating the fluid flowing through the recirculation pipe (48) medium. 17. The crosshead type large turbocharged two-stroke internal combustion engine according to claim 14, further comprising a second scavenging air cooler (19), wherein the electronic control unit (33) is configured to control the scavenging air cooler ( The cooling capacity of at least one of 18, 19). 18. The crosshead type large turbocharged two-stroke internal combustion engine as claimed in claim 11, further comprising a steam injection pipe (90) connected to the scavenging path (16), the steam injection pipe (50) comprising a The electronically controlled steam injection control valve (92) is controlled by the instruction of the electronic control unit (33). 19. The crosshead type large turbocharged two-stroke internal combustion engine according to claim 11, further comprising an exhaust gas injection pipe (60) connected to the scavenging path (16), the exhaust gas injection pipe (60) comprising a The electronically controlled exhaust gas injection control valve (92) is controlled by the instruction of the electronic control unit (33). 20. The crosshead type large turbocharged two-stroke internal combustion engine according to claim 11, further comprising a heater unit (27) in the scavenging path. 21. The crosshead type large turbocharged two-stroke internal combustion engine according to claim 20, wherein the heater unit (27) is operated with hot air as a heating medium. 22. The crosshead type large turbocharged two-stroke internal combustion engine as claimed in claim 14, further comprising a heat exchanger (80) in the cooling medium supply pipe (40) for supplying heat to the The medium of the cooling medium supply pipe (40).

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