KR101607654B1 - A large slow running turbocharged two-stroke internal combustion engine with crossheads and exhaust gas recirculation and method for operating thereof - Google Patents

Abstract

A crosshead type large-low-speed two-stroke-flow internal combustion engine (1) is disclosed. The engine 1 is provided with a plurality of cylinders 2 connected to the scavenge containing portion 11 and the exhaust gas receiving portion 6, a turbine T supplied with exhaust gas from the exhaust gas receiving portion 6, A turbocharger 7 having a compressor C for supplying the compressed air to the compressor 11 through the exhaust port of the compressor C of the turbocharger 7, And an exhaust gas recirculation path for recirculating at least a part of the exhaust gas from the cylinder (2) or the exhaust gas receiving portion (6) to the sorbent accommodating portion (11). The scavenging path has a separation point 23 at which the air flow path 26 is branched. The engine further includes a blower (30) which is supplied with exhaust gas from an exhaust gas recirculation path and which is branched from the blowing path (26), and the blower (30) (11).

Description

TECHNICAL FIELD [0001] The present invention relates to a large-sized low-speed turbo-charged two-stroke internal combustion engine having a crosshead and an exhaust gas recirculation function, and a method of operating the same.

The present invention relates to a large low speed turbocharged two-stroke internal combustion engine having a crosshead and an exhaust or combustion gas recirculation function. The present invention also relates to a method of operating a large low-speed turbocharged two-stroke internal combustion engine having a crosshead and an exhaust or combustion gas recirculation function.

A large low speed 2-stroke internal combustion engine with a crosshead is typically used in the propulsion system of large ships or as a prime mover in power plants. These engines have a crosshead disposed between the piston and the crankshaft. WO 02068809 discloses a large low speed 2-stroke internal combustion engine according to the preamble of claim 1.

Emission requirements are difficult to meet and are increasingly more difficult to meet, especially with respect to nitrogen oxide (NO _x ) levels.

Currently, there are many theoretical choices to reduce the formation of nitrogen oxides (NOx) in large-size low-speed turbocharged internal combustion engines, particularly with modifications applied to the following engine processes:

- Exhaust- or combusted gas recirculation (EGR)

- Use of water emulsified fuel

- Fresh charge humidification, ie Scavenge Air Moisterization (SAM)

- selective catalytic reactor (SCR) method

Exhaust gas recirculation (EGR) is a known action to support small high-speed traveling diesel engines to reduce NO _x emissions. However, to date, there are very few commercially available large two-stroke diesel engines that use the exhaust gas recirculation function. This is because the implementation of exhaust gas recirculation in large two-stroke diesel engines has proven to be a challenge. One reason that the implementation of exhaust gas recirculation in large two-stroke diesel engines has proven to be such a challenge is that these engines typically operate with heavy oil with a high sulfur content. As a result, the sulfur content of the exhaust gas is much higher than that of a small-sized diesel engine operating with a fuel flow path having a low or no sulfur content. Higher concentrations of sulfur greatly reduce the choice of cleaning methods and equipment because most of them endure sulfur and sulfuric acid levels present in the exhaust of large two-stroke diesel engines that burn heavy oil with high sulfur content It will not be possible.

One technique for cleaning exhaust gases in large two-stroke diesel engines capable of withstanding such high levels of sulfur is wet scrubbing. In this technique, the exhaust gas passes through a so-called wet scrubber using water as a cleaning solution.

Another challenge is the amount of power required to transport the recirculated exhaust gas from the exhaust gas receiver to the scavenging flow. In a large two-stroke diesel engine, the desired pressure is generally about 0.3 bar, which is higher than the pressure of the exhaust gas receiving portion of the large two-stroke diesel engine. Therefore, a blower or other means is required to force the recirculated exhaust gas from the exhaust gas receiving portion into the scavenging system. In large diameter 12 or 14-cylinder 2-stroke diesel engines, such as the MAN B & W 12K98MC-C engine, the power required to drive these blowers is close to 0.5 MW. This is a considerable amount of energy to use an electric motor on the exhaust system to drive the blower, and this large power demand is very expensive.

Thus, in exhaust gas recirculation systems for large diesel engines, the cost for machines such as, for example, wet scrubbers and blowers, amounts to a significant amount due to the dimensions of these components.

The large low-speed two-stroke internal combustion engine is designed so that when the engine is operated in intermediate to low load conditions, such as an engine maximum continuous rating of, for example, 25 to 45%, depending on engine and turbocharger characteristics, A secondary blower is needed to assist in achieving a sufficiently high scavenging pressure within the scavenging receptacle. Therefore, a dedicated auxiliary blower is provided in an existing large low-speed internal combustion engine to ensure operation during low to medium load conditions.

In view of the above, it is an object of the present invention to provide a large low-speed two-stroke loop internal combustion engine of a crosshead type and an exhaust gas recirculation (EGR) function having a simpler, more reliable and less expensive structure.

This object is achieved by providing a large-low-speed, two-stroke, single-flow internal combustion engine of the crosshead type, wherein the engine comprises a plurality of cylinders connected to the scavenging accommodating portion and the exhaust gas accommodating portion, A turbocharger having a compressor for supplying a turbine and a pressurized scavenger, a scavenging path for guiding the pressurized scavenging from the outlet of the compressor of the turbocharger to the scavenging storage portion, at least a part of the exhaust gas from the cylinder or the exhaust gas receiving portion And an exhaust gas recirculation path for recirculating the exhaust gas recirculated to the accommodating portion, wherein the exhaust path includes a blower having a separation point at which a blowing path is branched and supplied with exhaust gas from an exhaust gas recirculation path and supplied from a blowing path, Forcibly supplies the supplied exhaust gas and the supplied scavenging portion to the scavenging portion.

By providing a blower that receives both the scavenging and recirculating exhaust gases from the diverging air flow path, one blower can be used for both purposes, that is, it can support a turbocharger during low to medium load conditions, Thereby providing a flow of recirculated exhaust gas. This combination of blowers simplifies the engine configuration and reduces costs. By having only one blower, material and space can be saved in contrast to the two blowers having different functions.

In one embodiment, the scavenging path includes piping, scavengers upstream of the split point, a check valve downstream of the split point to prevent backflow during operation of the blower, and a mixer chamber downstream of the check valve. The check valve prevents reverse flow at low loads while the blower supports EGR operation and serves as an auxiliary blower for the turbocharger. During this dual function, gas mixing is sufficiently performed in the blower before the mixed gas enters the mixer chamber.

At high loads that do not require the support of an auxiliary blower, the mixer chamber mixes the recirculated exhaust gas with the desired main stream entering the mixer chamber from the common air passageway through the check valve.

In one embodiment, the outlet of the blower is connected to the inlet of the mixer chamber and the outlet of the mixer chamber is connected to the receiver via the check valve.

In one embodiment, the exhaust gas recirculation path includes piping and an EGR cooler.

In one embodiment, the auxiliary airflow path extends from the separation point to the inlet of the blower, and includes a blow-off control valve to control and balance the flow in the EGR flow and the flow in the scavenging path.

In one embodiment, the engine further includes a check valve in the air flow path to prevent back flow during operation of the blower.

In one embodiment, the engine further comprises a check valve upstream of the inlet of the blower to receive a flow of exhaust gas from the EGR passage, the check valve being configured to prevent backflow during normal operation of the engine in the absence of EGR operation do.

In one embodiment, the engine further comprises an electronic control device configured to maintain a predetermined scavenging pressure and a predetermined oxygen content or a CO2 content of the gas in the scavenging portion, for a given EGR rate.

In one embodiment, the electronic control device receives a signal indicative of oxygen content or CO2 content and a signal indicative of the expected pressure, and the electronic control device is configured to control the position of the blowing control valve and the flow of the EGR blower.

In one embodiment, the flow path leading the recirculated exhaust gas to the inlet of the blower includes an EGR control valve and the electronic control device is configured to control the position of the EGR control valve.

In one embodiment, the blower assists in achieving the desired scavenge pressure of the turbocharger's compressor, if necessary, and, if necessary, assists in achieving the required flow of recirculated exhaust gas.

This object is also achieved by providing a method of operating a large low-speed two-stroke overrun type internal combustion engine of the crosshead type,

A turbocharger having a plurality of cylinders connected to the scavenging portion and the exhaust gas receiving portion, a turbine for supplying the exhaust gas from the exhaust gas receiving portion, and a compressor for supplying the pressurized scavenging portion, An exhaust gas recirculation path for recirculating at least a part of the exhaust gas from the cylinder or the exhaust gas containing portion to the scavenging portion, an exhaust gas recirculation path for exhaust gas supplied from the exhaust gas recirculation path and branched from the exhaust path And using a blower to force the exhaust gas and the scavenging supplied by the blower to the scavenging receptacle.

In one embodiment, the method comprises the steps of continuously operating the engine with EGR, using a blower to enforce the EGR flow, and to assist the compressor of the turbocharger to achieve the desired pressure at low load conditions And using the blower to support the turbocharger for cooling the combustion chamber at high load.

The above objects are also achieved by providing a large-sized low-speed two-stroke overflow type internal combustion engine having a crosshead, each of the cylinders including a plurality of cylinders connected to a scavenging accommodating portion and an exhaust gas accommodating portion, A turbocharger having a compressor for supplying compressed air and a turbine for supplying pressurized air to the turbocharger, a scavenging path for guiding the pressurized scavenging from the outlet of the compressor of the turbocharger to the scavenging chamber, at least a part of the exhaust gas, An exhaust gas recirculation path for recirculating the exhaust gas recirculation path from the exhaust gas recirculation path to the scavenging portion, a blower for forcing the EGR flow to the scavenging portion, and a sensor for providing a signal indicative of the O2 level or CO2 level in the scavenging portion. The electronic control device receives a signal from the sensor, and the electronic control device is configured to control the flow of EGR corresponding to the signal from the sensor.

Additional objects, features, advantages and characteristics of a large low speed turbo charged two-stroke internal combustion engine and method according to the present invention will be apparent from the detailed description.

In the following detailed description of the present description, the invention will be described in more detail with reference to exemplary embodiments shown in the drawings, wherein:
1 is a schematic view of an engine according to an exemplary embodiment,
2 is a detailed view of an electronic control device and a control valve of the engine of Fig. 1, and Fig.
3 is a schematic diagram of an engine according to another exemplary embodiment;

In the following detailed description, a large low speed turbocharged two-stroke internal combustion (diesel) engine with a crosshead according to the present invention will be described by way of an exemplary embodiment.

The construction and operation of a large low-speed turbocharged two-stroke internal combustion engine with a crosshead is well known and does not require further explanation in this context. Further details on the operation of the exhaust system are provided below.

FIG. 1 shows a first exemplary embodiment of a short-flow type large low-speed turbocharged two-stroke internal combustion (diesel) engine 1. The engine 1 can be used, for example, as a main engine at the source line or as a stationary engine for operating a generator at a power plant. The total output of the engine may range, for example, from 2,000 to 110,000 kW.

The engine has a plurality of cylinders (2) arranged in series with each other. Each cylinder 2 has an exhaust valve 3 coupled with a cylinder cover. The exhaust channel can be opened and closed by the exhaust valve 3. [ The crosshead 4a of the engine and the connecting rod 4b, which connect the piston rod to the large end of the crankshaft, are also shown. The exhaust bend (5) is connected to the exhaust gas receiving portion (6). The exhaust gas receiving portions 6 are arranged in parallel in a row of cylinders 2. From the exhaust gas receiving portion 6 at least a substantial portion of the exhaust gas is directed through the exhaust conduit to the turbine T of the turbocharger 7 (there may be more than one turbocharger 39). Another portion of the exhaust gas is recirculated and enters the exhaust gas recirculation flow path, which will be described in more detail below. The exhaust gas is treated through the exhaust gas bypass 54 to the atmosphere downstream of the turbine of the turbocharger 7 through the exhaust ports 9a and 9b or the exhaust port 9c.

The turbocharger 7 also includes a compressor C connected to a fresh air inlet 10a. The compressor C conveys the pressurized stuff to the scavenging receiver 11 through the scavenging channel 12 including the cooler 12 and the water mist catcher 13 in an exemplary embodiment. The water spray collector 13 removes all the water that condenses when the scavenge is cooled. The desired pathway extends from the water mist collector through the check valve 24 to the mixer chamber 25. The mixer chamber 25 also receives recirculated exhaust gas from an exhaust gas recirculation path, which will be described in more detail below.

The scavenge flow path includes a split point (23) downstream of the water spray collector (13) and upstream of the check valve (24). The blow conduit 26 extends between the separation point 23 and the inlet of the blower 30. The blow conduit 26 allows some or all of the draft to flow into the inlet of the blower 30. The blow conduit 26 includes a check valve 27 and a blowing control valve 28.

The scavenge enters the mixer chamber 25 from the separation point via the check valve 24 or through the blow conduit 26 and the blower 30.

The scavenge entering the mixer chamber 25 through the check valve 24 is mixed with the recirculated exhaust gas during the EGR operation and the outlet of the mixer chamber 25 is connected to the scavenging accommodating portion 11 through the check valve 31 do. The scavenging path is a scavenging path including the scavenging cooler 12, the water mist collecting device 13, the separation point 23, the check valve 24, the mixer chamber 25 and the check valve 31 in an exemplary embodiment Is part of the device 36.

The scavengers mixed with the scavenging or recirculating exhaust gas are passed from the scavenging receptacle 11 to the scavenging port 14 of each cylinder 2.

An exhaust gas bypass 54 is provided to handle the quick braking operation of the engine and / or is used with an exhaust gas bypass connected to the turbocharger in high load operation to prevent overloading of the turbocharger.

A cylinder bypass 47 may be added to reduce the differential pressure between the exhaust gas receiving portion 6 and the scavenge receiving portion 11. [ When hot air is passed from the compressor (C) outlet of the turbocharger (7) to the exhaust gas receiving portion (6), less power will be required by the blower (30) to overcome the reduced differential pressure. The bypass inlet 61 to the exhaust gas receiving portion 6 is disposed away from the exhaust gas recirculation device 37 so as not to reduce the CO 2 concentration of the exhaust gas guided to the exhaust gas recirculation device 37.

The exhaust gas receiving portion 6 is also connected to an exhaust gas recirculation path which forms a part of the exhaust gas recirculation device 37 by an exhaust port 62. The exhaust gas recirculation device 37 may be disposed on or near the engine. The recirculation path includes a pre-scrubber 15 followed by an EGR cooler 16 followed by a scrubber 17 followed by a water spray collector 18 followed by a gas suction The thread 19 follows. The cleaning devices 15, 17 are, in one embodiment, a wet cleaning device in which exhaust gas is contacted with cleaning droplets and streams which are atomized and evaporated from the at least one nozzle into the exhaust gas. Cleaning droplets and streams are generally water-based. The cleaning droplets and streams absorb particles such as catalyst particles, fuel residues, gases such as soot particles and sulfides, and clean exhaust gases. Besides the exhaust gas cleaning, the wet scrubbing action also cools the exhaust gas. The exhaust gas is cooled in the EGR cooler 16 and the water can be condensed in the EGR cooler 16. A water spray collector 18 (separate means) collects the condensed water as well as the small water droplets that can be transferred from the cleaning apparatus by the gas flow. The water collected in the water spray collector 18 can be discharged through a drain (not shown) and reused after the washing process.

The exhaust gas recirculation device 37 can be used in two basic and different ways:

- in normal operation

- EGR operation

Further details regarding the operation of the system of the exhaust gas recirculation device 37 are provided below.

During normal operation:

The exhaust gas recirculation device 37 serves as a general air cooling device together with a closing valve 43, open valves 41, 42 and a running turbocharger 39. The general air is passed through the exhaust gas recirculation device 37 without the aid of a cleaning device and finally guided to the scavenging accommodating portion 11 through the check valve 29 at an intermediate load and a high load. At low load, air enters the mixer chamber 25 and passes through the conduit 21 and the blower 30 before passing through the scavenging receiver 11 through the check valve. Thus, the exhaust gas recirculation device 37 serves as a general air cooling device here. The shutoff valve 41 and shutoff valve 42 are used to connect or disconnect the second turbocharger 39. When the second turbocharger 39 is in operation, its compressor C delivers the compressed air directly to the EGR cooler 16, and the precleaner 15 is bypassed. To this end, the shut-off valve 43 in the conduit 62 extending between the exhaust gas receiving portion 6 and the precleaner 15 is closed. An EGR-free operation can be selected if the base engine without EGR matches emissions Tier 2.

Blower 30 may be used at low loads as an auxiliary blower if the desired pressure provided by both turbochargers 7 and 39 is not sufficient to ensure proper combustion. In this case, the air flows from the EGR cooler 16 through the non-operational cleaner 17, the water spray collector 18, the gas suction chamber 19, the conduit 21, through the blower 30 to the mixer chamber 25 Through the check valve 31, and through the scavenging accommodating portion 11.

EGR  In operation

The exhaust gas recirculation device 37 serves as an exhaust gas scrubbing device together with the opening valve 43, the closing valves 41 and 42 and the inoperative turbocharger 39. The exhaust gas is passed from the exhaust gas receiving portion 6 to the cleaning device 15 through the opening portion 62. The exhaust gas is cooled and cleaned in the precleaner 15 before the water and gas are directed to the EGR cooler 16 for further cooling. The flow continues to the scrubbing device 17 for further scrubbing and to capture most of the scrubbing water from the exhaust gas. The cleaned and cooled exhaust gas passes through the additional water collector 18 before entering the gas suction chamber 19. When the pressure in the gas suction chamber 19 is lower than the pressure in the scavenging accommodating portion 11, the check valve 29 is closed. The outlet of the gas suction chamber 19 is connected to a conduit 21 leading to the inlet of the blower 30. The conduit 21 includes a check valve 20 and an EGR control valve 22. The check valve 20 prevents backflow during operation of the blower.

The blower 30 is supplied with exhaust gas from the EGR passage and scavengers diverged from an air flow path (conduit) 26. The blower 30 is operated by an electric drive motor or a hydraulic drive motor or a steam turbine or an exhaust gas expander to increase the exhaust gas and / (11). The operation of the blower (blower speed and / or diffuser position) is controlled by the electronic control unit (ECU) shown in Fig.

The electronic control device receives from the sensor 51 a signal indicating the level (content) of oxygen (O2) or the level (content) of carbon dioxide (CO 2) in the scavenging container 11, From the pressure sensor (52). 2, the electronic control device sends a control signal to the air flow control valve 28 in conduit 26 and / or to the EGR control valve 22 in conduit 21. The electronic control unit is configured (by EGR amount) to ensure that the engine is operated at a predetermined scavenge oxygen or CO2 content and at a sufficient scavenge pressure. The engine 1 can be flexibly changed between operations having various amounts of EGR under the control of the electronic control unit. Where the engine is a marine engine, it may be desirable to meet geographically diverse exhaust gas requirements, such as restrictions on NOx production. Examples of these requirements are the IMO NOx phase-II and phase-III regulations.

The pressure drop from the turbocharger compressor C to the inflow port of the blower 30 is lower than the pressure drop from the exhaust gas receiving portion 6 above the EGR module 37 to the inflow port of the blower 30 ), The blowing control valve 28 can control the scavenging from the separation point. Adjustment of the airflow control valve 28 will balance the flow from the scavenging module 36 and the EGR module 37 and thereby control the amount of EGR.

The total mixing mass flow rate is controlled by the speed of the blower 30 under command from the electronic control unit and / or by the diffuser position of the blower 30.

The flow through conduit 27 is required for high EGR flow in a load immediately prior to the normal auxiliary blower setting (stage III mode at approximately 25-30% load), with vent control valve 28 fully open. The EGR rate is set to be given.

For the phase III mode with low NOx limit, the EGR rate is increased by the blower flow so that the desired oxygen content can be reached within the scavenging receiver 11. [ At low load, conduit 26 is also included to support turbocharger 7. The blowing control valve 28 can be adjusted to obtain the correct scavenging pressure and the oxygen content in the scavenging accommodating portion 11. [

Simplified settings:

Figure 3 shows another exemplary embodiment similar to the previous embodiment but with a simpler setting. In the present embodiment, the EGR system is continuously driven. This embodiment simplifies the configuration and uses components in a dual configuration, such as, for example, an EGR cooler at all times under wet driving conditions. The wet cooler surface also serves as a cleaning device. Therefore, the cleaning device 17 is not required. The present embodiment does not include the EGR valves 43 and 22 since the blower is continuously driven and the flow is completely controlled over the mode and the load mode together with the flow of the EGR blower 30. [ One check valve 20 is included to prevent back flow to the EGR device 37, which may be involved in low load operation or blower failure. However, since the check valve 29 connects the EGR device 37 directly to the scavenging receiver 11, there is no second turbocharger, shut-off valves 41, 42 and conduits, because the need for these components There is no. The turbocharger 7 may be set according to various matching strategies that may vary depending on the application of the conduit 54. In the simplest setting, the turbocharger can be set without the conduit 54. In addition, since the present embodiment assumes that the engine control system processes the braking operation sufficiently fast to prevent the overspeed of the turbocharger 7, the present embodiment does not include the exhaust gas bypass 54. [ This embodiment uses one blower or one or more parallel blowers 30 for auxiliary blowing and for EGR blowing. If the EGR blower 30 is set accordingly, the conduit 47 may be omitted. In the present embodiment, the EGR cooler 16 will continue to operate under wet drive conditions. The wet cooler surface serves as a cleaning device at the same time and therefore no separate cleaning device 17 is required. Control valve 22 is not required in EGR conduit 21 because blower 30 continues to operate and flow is fully controlled with blower 30 and control valve 28 and over the load mode.

The following table shows examples of possible operating modes for the embodiment of Figure 3:

Mode 2 Mode 3 Mode 4 No EGR Low EGR High EGR Load range 0-50% 0-110% 0-110% EGR blower function No flow Low flow rate High flow rate Auxiliary blower function Low load Low load Low load Fail Safe Mode 2 2 2 Emission level - Step II Step III

Mode 2 is a failure safe mode in the case where the blower fails in which mode 3 or mode 4 can not be used. Mode, the load is limited by the maximum capacity of the turbocharger (7).

Mode 3 is a low EGR mode, for example to meet the IMO Phase II emission requirements. The engine can be operated in a load range of 0 to 100%. The blower 30 is used to provide a sufficient flow of recycle exhaust gas to reach a low flow of recirculated exhaust gas, i. E. An EGR amount resulting in a NOx emission cycle value below the threshold of step II. The amount of EGR is, for example, in the range between 0 and 15%. In this mode, when the engine load is moderate to high (e.g., 25% or more) and the compressor C of the turbocharger 7 does not need to assist in achieving the desired scavenging pressure, do. If the load is low such as, for example, 0 to 25%, the blowing control valve 28 is opened or adjusted, and the blower 30 can not support that the compressor C of the turbocharger 7 achieves the required scavenging pressure The blower 30 has a dual function.

Mode 4 is, for example, a high EGR mode to meet IMO Phase III emission requirements. The engine can be operated in a load range of 0 to 110%. The blower 30 is used to provide sufficient flow of recirculated exhaust gas, i. E., Sufficient flow of recirculated exhaust gas to reach an EGR amount that results in a NOx emission cycle value below the critical step III threshold. The amount of EGR is, for example, in the range between 30 and 40%. In this mode, when the engine load is above a medium to high load, for example 25%, and the compressor C of the turbocharger 7 does not need to assist in achieving the required scavenging pressure, Lt; / RTI > If the load is low such as, for example, 0 to 25%, the blowing control valve 28 is opened or adjusted, and the blower 30 can not support that the compressor C of the turbocharger 7 achieves the required scavenging pressure The blower 30 has a dual function.

The teachings of the present invention have many advantages. Various embodiments or implementations may achieve one or more of the following advantages. It should be noted that this is not a complete list and there may be other advantages not disclosed herein.

One advantage of the teachings of the present application is that it provides a simpler configuration of the gas exchange system of a large low speed two-stroke internal combustion engine with exhaust gas recirculation function. Another advantage is that it provides more flexible operation of a large low speed two-stroke internal combustion engine with exhaust gas recirculation capability that enables fuel optimized operation in IMO phase II exhaust mode at partial load. However, it is evident to reduce the number of components to reduce the final cost of the present application.

Although the teachings of the present application have been described in detail for purposes of illustration, it is to be understood that such detail is solely for that purpose and that modifications may be made by those skilled in the art without departing from the scope of the present application. Embodiments can adjust the principle for large engines that require many turbochargers and exhaust systems in parallel to cover the flow requirements. The same adjustments may be considered for blower applications, where one or more blowers are typically installed due to the flow capacity requirements or by simple requirements for unnecessary duplication of auxiliary blower operation.

It should also be noted that there are many other ways of implementing the teachings of the present invention. For example, a blower for increasing the pressure of both recirculated exhaust gas and scavenging can be retrofitted to existing engines. An integrated engine system or a stand alone exhaust gas device disposed near the engine and coupled to the engine by a conduit is identified.

In another exemplary embodiment, a large-sized low-speed two-stroke-flow internal combustion engine 1 having a crosshead has a plurality of cylinders 2 connected to the scavenging accommodating portion 11 and the exhaust gas accommodating portion 6, A turbocharger 7 having a turbine T for supplying the exhaust gas from the exhaust gas receiving portion 6 and a compressor C for supplying pressurized scavenging gas to the compressor (not shown) of the turbocharger 7 An exhaust gas recirculation path for recirculating at least a part of the exhaust gas from the cylinder 2 or the exhaust gas receiving portion 6 to the scavenging accommodating portion 11, A blower 30 for forcing the EGR flow into the scavenging portion, and a sensor 51 for providing a signal indicative of the O2 level or the CO2 level in the scavenging portion 11. The electronic control unit ECU is configured to receive a signal from the sensor 51 and the electronic control unit ECU to control the EGR flow in response to the signal from the sensor 51. [

In another exemplary embodiment, the large-sized low-speed two-stroke single-flow type internal combustion engine having a crosshead includes a plurality of cylinders 2 connected to the scavenging accommodating portion 11 and the exhaust gas accommodating portion 6, A turbocharger 7 having a turbine T supplied with exhaust gas from the storage portion 6 and a compressor C supplying compressed raw material to the compressor C of the turbocharger 7, An exhaust gas recirculation path for recirculating at least a part of the exhaust gas from the cylinder 2 or the exhaust gas receiving portion 6 to the scavenging accommodating portion 11, A blower 30 for forcing the flow to the scavenging portion, and a sensor 51 for providing a signal indicative of the level of O2 or the level of CO2 in the scavenging portion 11. The electronic control unit ECU is configured to receive a signal from the sensor 51 and the electronic control unit ECU to control the EGR flow in response to the signal from the sensor 51. [

When the O2 level is measured, the electronic control unit ECU controls the O2 level in the scavenging portion 11 to increase the EGR amount when the O2 level in the scavenging receiver 11 is equal to or higher than the threshold in the embodiment, And to reduce the EGR amount when the temperature is below the threshold value.

When the CO2 level is measured, the electronic control unit ECU controls the EGR amount to be reduced when the O2 level in the scavenging receiver 11 is equal to or higher than the threshold in the embodiment, and if possible, the CO2 level in the scavenging receiver 11 And to increase the EGR amount when it is equal to or larger than the threshold value.

In the modification of the present embodiment, the electronic control unit ECU is configured to control the EGR amount by adjusting the speed of the blower 30. [

As used in the claims, the term " comprising " does not exclude other elements or steps. As used in the claims, the term "one" does not exclude a plurality.

The electronic control device may perform the functions of various means recited in the claims.

Reference numerals used in the claims should not be construed as limiting the scope.

Although the present invention has been described in detail for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that modifications may be made by those skilled in the art without departing from the scope of the present invention.

Claims (13)

A large-sized low-speed two-stroke single-flow type internal combustion engine (1) having a crosshead, wherein the engine (1)
A plurality of cylinders 2 connected to the scavenging accommodating portion 11 and the exhaust gas accommodating portion 6,
A turbocharger 7 having a turbine T for receiving exhaust gas from the exhaust gas receiver 6 and a compressor C for supplying pressurized scavengers,
A scavenging path for guiding the pressurized scavenging from the outlet of the compressor (C) of the turbocharger (7) to the scavenging accommodating portion (11)
An exhaust gas recirculation path including a blower (30) for recycling at least a part of the exhaust gas from the cylinder (2) or the exhaust gas receiving portion (6) to the scavenging accommodating portion (11)
The scavenging path has a separation point (23) at which the air flow path (26) branches,
The blower 30 is supplied with exhaust gas from the exhaust gas recirculation path and receives the exhaust gas branched from the blowing path 26. The exhaust gas is supplied to the blower 30 and the exhaust gas is supplied to the blower accommodating portion 11 ,
Characterized in that the air flow path (26) extends from the separation point (23) to the inlet of the blower (30). The method according to claim 1,
The scavenge path includes a pipe, a scavenge cooler 12 upstream of the separation point 23, a check valve 24 downstream of the separation point 23 to prevent backflow during operation of the blower 30, And a mixer chamber (25) downstream of the valve.
3. The method of claim 2,
Wherein an outlet of the blower is connected to an inlet of the mixer chamber and an outlet of the mixer chamber is connected to the scavenging chamber via a check valve. .
4. The method according to any one of claims 1 to 3,
Characterized in that the exhaust gas recirculation path comprises piping and an exhaust gas recirculation (EGR) cooler (16).
The method according to claim 1,
Characterized in that the air flow path (26) comprises an air flow control valve (28) for controlling the flow in the air flow path.
The method according to claim 1,
Further comprising a check valve (20) upstream of an inlet of a blower (30) supplied with a flow of exhaust gas from the EGR passage, wherein the check valve (20) is configured to prevent reverse flow in the event of operation or failure of the blower (1).
6. The method of claim 5,
Characterized by further comprising an electronic control unit (ECU) configured to maintain a predetermined scavenging pressure and a predetermined oxygen content level or a CO2 content level of the gas in the scavenging container (11), for a predetermined EGR rate, (One).
8. The method of claim 7,
Characterized in that the electronic control unit (ECU) is configured to receive a signal indicative of oxygen content or a CO2 content and a signal indicative of an evacuation pressure, and the electronic control unit (ECU) is configured to control the position of the blowing control valve (1).
9. The method of claim 8,
The electronic control unit ECU maintains the blowing control valve 28 in an open state by controlling the speed of the blower 30 and when the desired pressure delivered by the compressor of the turbocharger is insufficient during low load engine operation And to control the air pressure and the oxygen content or the CO2 content in the scavenging receptacle by closing the air flow control valve 28 when the desired pressure delivered by the compressor of the turbocharger is sufficient during medium to heavy load engine operation Institutions featured (1).
9. The method of claim 8,
Characterized in that the flow path for leading the recirculated exhaust gas to the inlet of the blower (30) includes an EGR control valve (22) and the electronic control unit (ECU) controls the position of the EGR control valve Agency (1).
The method according to claim 1,
Characterized in that the blower (30) supports, if necessary, the compressor of the turbocharger to achieve the desired scavenging pressure and, if necessary, to achieve the required flow of recirculated exhaust gas.
A method of operating a crosshead type large-low speed two-stroke interrupting internal combustion engine (1), wherein the engine (1)
A plurality of cylinders 2 connected to the scavenging accommodating portion 11 and the exhaust gas accommodating portion 6,
A turbocharger 7 having a turbine T for receiving exhaust gas from the exhaust gas receiver 6 and a compressor C for supplying pressurized scavengers,
A scavenging path for guiding the pressurized scavenging from the outlet of the compressor (C) of the turbocharger (7) to the scavenging accommodating portion (11)
An exhaust gas recirculation path for recirculating at least a part of the exhaust gas from the cylinder (2) or the exhaust gas receiving portion (6) to the scavenging accommodating portion (11)
And a blower (30) which is supplied with exhaust gas from the exhaust gas recirculation path and is supplied with exhaust gas branched from the blowing path (26)
Characterized in that said method comprises the step of using said blower (30) to force exhaust gas and scavenging supplied by said blower into said scavenging receiver (11).
13. The method of claim 12,
The method further comprises continuously operating the engine (1) with EGR, using the blower (30) to enforce the EGR flow, and operating the compressor of the turbocharger (7) ≪ / RTI > further comprising the step of using the blower to assist in achieving the desired performance.

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