KR102221645B1 - A system for exhaust gas recirculation, engine, use of a system for exhaust gas recirculation, method for exhaust gas recirculation and diesel exhaust composition - Google Patents

Abstract

An exhaust gas recirculation system 1 is disclosed which can be arranged between the exhaust outlet 2 and the air inlet 3 of an engine, preferably a two-stroke engine. The system comprises a first turbocharger (4) in the first function duct (5) between the exhaust outlet (2) and the air inlet (3) and a second function between the exhaust outlet (2) and the air inlet (3). And a second turbocharger 6 in the duct 7. The first and second turbochargers 4, 6 are arranged individually and in parallel, preferably the first functional duct 5 and the second functional duct 7 are arranged individually and in parallel. The system further comprises an exhaust gas purification device 8 disposed in an air duct 9 disposed between the exhaust outlet 2 and the air inlet 3, and a control unit for controlling the functional state of the system 1. Includes. The air duct 9 is at least partially arranged in parallel with the second functional duct 7 and the control unit is a first inlet valve ( 10) and the second inlet valve 11 arranged upstream of the second turbocharger 6 so that both the first inlet valve 10 and the second inlet valve ( 11).

Description

A SYSTEM FOR EXHAUST GAS RECIRCULATION, ENGINE, USE OF A SYSTEM FOR EXHAUST GAS RECIRCULATION, METHOD FOR EXHAUST GAS RECIRCULATION AND DIESEL EXHAUST COMPOSITION }

The present invention relates to an exhaust gas recirculation system according to the independent claim, an engine, the use of the system, an exhaust gas recirculation method and a diesel exhaust gas composition.

As a way to reduce NO _X emissions, externally recirculating (cooled) exhaust gas into the intake of diesel engines (EGR) is known and has been used for a long time in the automotive field. For large marine two-stroke diesel engines, this technology still needs to be improved. Therefore, it is generally known to recirculate the exhaust gas from the exhaust outlet of the engine to the air inlet of the engine for optimization of combustion.

When residual fuel oils containing up to 3.5% m of sulfur are used, sulfuric acid (H ₂ SO ₄ ) is present in the exhaust gas, which is produced as _{combustion products SO X} and H _{2 O.} Recirculation of acidic exhaust gases causes corrosion on engine parts. In addition, when the residual fuel is burned, more particulate matter (PM) is produced than the distillate fuel. Thus, when the exhaust gas having a lot of particulate matter is recycled, there is a risk that engine parts that come into contact with the exhaust gas will be excessively contaminated.

Patent application DE 10 2012 009 319 discloses an exhaust gas recirculation system for marine diesel engines. The exhaust gases from this system are used to power the compressor that compresses the exhaust gases returning to the inlet of the engine. This system uses recirculating gas, but requires a turbocharger in the exhaust gas purification duct. So, if the exhaust gas does not pass through the purification device, the turbocharger cannot be used.

DE 10 2012 009 315 discloses an exhaust gas purification device, in which the exhaust gas can be recirculated through the purification device or power a second turbine. There is no possibility that the exhaust gas will power the second turbine at the same time and be recycled.

Document WO 2011/141631 discloses an apparatus for exhaust gas recirculation and turbocharging, in which two turbochargers are arranged in series before and after each other. Turbocharging in two stages in series is more complicated than parallel turbocharging.

Document DE 10 2012 009 319 discloses a combustion engine with exhaust gas recirculation, in which the exhaust gas is used to energize the compressor or is recycled through a purifying device. It does not make the amount of cleansing suitable for the required situation.

DE 103 31 187 discloses an engine with exhaust gas recirculation, in which the heat of the exhaust gas is used to power the exhaust gas recirculation device. There is no disclosure of the amount of exhaust gas to be recycled and adaptation to the exhaust situation.

WO 94/29587 discloses exhaust gas recirculation for large turbocharged diesel engines, in which an exhaust purification device is arranged in series with a turbocharger. So, since the exhaust gas from the engine is first purified and then entered into the turbocharger, an efficiency factor is possible. The air reaching the turbocharger has already lost a significant amount of energy.

It is an object of the present invention to realize an exhaust gas recirculation system, an engine, an exhaust gas recirculation method and a diesel exhaust gas composition which can avoid the disadvantages of the prior art and in particular adapt the exhaust gas composition to a desired value.

This object is achieved with the system, engine, method and exhaust gas composition according to the independent claims.

In particular, the above object is achieved with an exhaust gas recirculation system that can be arranged between the exhaust outlet and the air inlet of the engine. The engine is preferably a two-stroke engine. The system includes a first turbocharger and a first functional duct between the exhaust outlet and the air inlet, and a second turbocharger and a second functional duct between the exhaust outlet and the air inlet, the first and second 2 Turbochargers are individually and arranged in parallel. Preferably the first functional duct and the second functional duct are arranged individually and in parallel. The exhaust gas recirculation system further includes an exhaust gas purification device disposed in an air duct disposed between the exhaust outlet and the air inlet. Additionally, the system includes a control unit for controlling the functional state of the system. The air duct is at least partially arranged in parallel with the second functional duct, and the control unit is arranged upstream of the first inlet valve and the second turbocharger arranged in the air duct upstream of the exhaust gas purification device. It is adapted to control the first inlet valve and the second inlet valve so that both of the located second inlet valves can simultaneously assume an at least partially open position.

By means of an exhaust gas recirculation system having two inlet valves capable of simultaneously taking an at least partially open position, it is possible to cause exhaust gas recirculation to take place independently of the engine power. Additionally, it is possible to use two turbochargers in parallel and also to further purify and recycle a part of the exhaust gas. Thus, such a system can easily adapt the exhaust gas composition to the required standard.

The exhaust outlet is disposed at the outlet of one or more cylinders of the combustion engine. The air inlet of the engine preferably comprises a scavenge air receiver.

The functional duct according to the invention uses exhaust gas to power the turbocharger and directs fresh air to the air inlet of the engine. The air duct according to the present invention sends exhaust gas from the exhaust outlet to the air inlet of the engine.

The inlet valves can take an at least partially open position, so that the air duct and the second functional duct can be used in parallel. The control unit can control the opening of both valves from full to full open independently of the other valves. Also, the position of the valve can be adapted to the situation.

The first functional duct comprises a first cooler downstream of the first turbocharger and a first water mist collector, preferably downstream of the first cooler.

By placing the cooler downstream of the turbocharger, the cooled air has a higher density compared to the warm air, so the effective factor of the engine is higher. The water mist collector dries the air so less corrosion occurs in the combustion chamber.

The exhaust gas purification device includes a scrubber and at least a second water mist collector.

The scrubber can be used to purify the exhaust gas with a water mist collector that catches the water introduced into the exhaust gas by the scrubber.

The scrubber may be a combined scrubber for collecting gas and removing particulate matter.

To prevent contamination and corrosion of downstream components, scrubbers are used to prevent particulate matter from recirculating exhaust gases. SO ₃ and H ₂ SO ₄ must be removed. Various scrubber technologies for scrubbing exhaust gas are known, but there are no commercialized products in compact form used for high pressure applications. Dry and semi-dry scrubbers are available, which are very efficient in degassing. Also, dry scrubbers are large and heavy, so it is almost impossible to add a dry scrubber to a marine engine. Other types of scrubbers, such as wet or electric cyclone scrubbers, are most efficient for particulate matter removal. If different types of scrubbers are combined, the auxiliary device for that scrubber must use the same medium or detergent. In this way, economic integration of the combined scrubber is achieved.

Condensation will occur in the air duct due to the water generated during the combustion process and the necessary cooling of the recirculating exhaust gas to 30-35°C. The condensate must be collected, treated and discharged or stored. So, an on-board device for treatment of condensate or scrubber water must be installed. In the case of a wet scrubber, the condensate treatment device can be additionally designed and used for scrubber water treatment. No additional scrubber detergent handling device is required. Since wet scrubbers can remove gaseous contaminants and particulate matter with high efficiency, wet scrubbers combine the requirements mentioned above and are the most preferred scrubber type when bonding is not necessary or possible.

In wet scrubbers, scrubber water treatment devices such as neutralization units, water supply and sludge tanks or water separation units are required. The cleaning liquid may be sea water (open loop system) or fresh water (closed loop system) having an appropriate alkalinity for acid neutralization.

Possible scrubbers are plate tower scrubbers, spray tower scrubbers or _{ejector venturi scrubbers for SO 2} absorption and/or venturi scrubbers or multiple venturi scrubbers for particulate matter removal.

Downstream of the second water mist collector is a pressure increasing device such as a blower or compressor.

This blower can preferably be driven electrically or mechanically at a controllable speed. Due to this variability, it is possible to adjust the exhaust gas flow rate and pressure increase relatively simply according to the engine load point and adjustment requirements.

Using a pressure increasing device, the exhaust gas recirculation system can also be used in two-stroke engines. In the absence of a pressure increasing device, the exhaust gas recirculation system can only be used for four-stroke engines.

The second functional duct may comprise a second cooler downstream of the second turbocharger.

With the use of the second cooler, the efficiency factor of the engine becomes larger because the cooled air is denser than the warm air directly out of the exhaust gas.

The first valve can be arranged immediately downstream of the second turbocharger.

Due to the first valve immediately downstream of the second turbocharger, it is possible to completely shut off the second turbocharger and also use exhaust gas recirculation only in the tucks for a portion of the exhaust gas.

The term "right" can be understood to mean that there is no other device between the turbocharger and the valve that affects the air leaving the turbocharger. Of course, there may be lines between the valve and the turbocharger, which may have different lengths or diameters.

The air duct may include a third cooler disposed upstream of the exhaust gas purification device.

By the third cooler, the air passing through the exhaust gas purification device is also cooled, so that the efficiency factor of the engine becomes larger.

The second cooler and the third cooler may be combined coolers disposed downstream of the second turbocharger and downstream of the first valve in the air duct.

Combined coolers require only one component and are easy to install. The air duct may comprise a coupling line valve downstream of the combined cooler. The coupling line valve is preferably a three-way valve.

By means of the coupling line valve, it is possible to select whether to pass the cooled exhaust gas or fresh air through the scrubber or bypass the scrubber. So, the amount of contaminant can be adapted depending on the required situation.

The exhaust gas purification device may include a bypass duct between the coupling line valve and the second water mist collector to bypass the scrubber.

By bypass, the air can bypass the scrubber so that the use of the scrubber can be avoided or the air can be avoided passing through the scrubber when the scrubber is not used.

In this way, the life of the entire system is prolonged.

Two three-way valves are arranged in series downstream of the third cooler, the air duct is connected to the second functional duct by two connection lines, and the first connection line is a first three-way valve It starts at and is connected to the second functional duct at a first connection point just upstream of the second cooler. A second connection line starts at a second three-way valve and is connected to the second functional duct at a second connection point just downstream of the second cooler. A first check valve is disposed upstream of the first connection point and a second check valve is disposed downstream of the second connection point.

With this configuration, the combined operation of the first turbocharger and the second turbocharger and purification of exhaust gas in the air duct becomes possible. Additionally, the second turbocharger can be stopped and only the air duct can be supplied with completely purified exhaust gas. For this case, the first and second coolers are arranged in series, so it is advantageous to obtain a higher cooling performance than if there is only one cooler. Also, this configuration is extremely reliable in its use.

The two three-way valves downstream of the third cooler can be combined into one valve, preferably one flap.

By combining the two valves into one, manufacturing costs are lowered and space for installation of the entire system can be optimally used.

After the connection point, a valve, preferably a flap, can be arranged downstream of the second connection point.

By means of a valve after the connection point, complete air or exhaust gas can be passed through the purification system of the exhaust gas recirculation system.

A third water mist collector may be disposed downstream of the valve after the connection point.

Dry air is obtained by a third water mist collector in the second function duct, which is supplied to the air inlet of the engine. In this way, less corrosion.

Alternatively, two three-way valves are arranged in series downstream of the third cooler, the air duct being connected to the second functional duct by two connecting lines. The first connection line starts at the first three-way valve and is connected to the second functional duct at a third three-way valve upstream of the second cooler, and the second connection line is at the second three-way valve. It is started and connected to the second functional duct at a fourth three-way valve immediately downstream of the second cooler.

With this configuration, as in the previous configuration, a second turbocharger or air duct or a combination thereof can be used. In this way, a very flexible system is obtained that can be adapted to the required situation.

A preliminary water mist collector may be arranged downstream of the third cooler.

This preliminary water mist collector improves the efficiency of the scrubber so that a cleaner recycled exhaust gas is obtained.

A preliminary scrubber may be disposed downstream of the first inlet valve.

By means of a preliminary scrubber, the purification of the exhaust gas is made more efficient and can also help to keep the surface of the third cooler clean.

The recirculating exhaust gas must be cooled to the scavenging air temperature before it is mixed with the scavenging air. The target temperature is 30 to 35℃ under ISO conditions. When a wet scrubber with a recirculation rate of 40% is used, about 40% of the total exhaust gas energy is dissipated in the scrubber water, unless a heat exchanger is used upstream of the scrubber. Due to the high temperature of the exhaust gas before the turbine (350-500° C.), the design of an exhaust gas recirculation system including a heat exchanger is advantageous in terms of waste heat recovery (eg, the recovered energy can be used for operation of a fresh water generator).

Two types of heat exchangers (also called coolers) can be used. First, there is a dry heat exchanger, where the outlet temperature of the exhaust gas is higher than the dew point of water vapor and no condensate is formed due to the cooling process. In order to prevent deposits from accumulating on the surface of the cooler, the gas velocity passing through the heat exchanger is required to be relatively high, which in turn increases the pressure loss in the heat exchanger. Second, there is a wet heat exchanger, where the temperature of the exhaust gas at the outlet of the cooler is intentionally lower than the dew point of the water vapor. The condensate permanently purifies the cooler tube. In order to increase the purification effect by the increased condensate flow, an additional preliminary scrubber can be installed, for example water sprayed upstream of the heat exchanger.

On the other hand, since the outlet temperature is not limited by the dew point temperature, the energy recovered is greater in the case of a wet heat exchanger than in the dry heat exchanger. On the other hand, the choice of heat exchanger can be limited by the type of scrubber and its requirements, for the exhaust gas conditions at the scrubber inlet, ie saturation and loading with water droplets. The heat exchanger material also depends on the dry and wet mode of operation.

A third water mist collector may be disposed downstream of the fourth three-way valve.

The third water mist collector removes moisture from the air, so that less corrosion occurs in the engine when air is introduced into the cylinder.

Any of the previously mentioned systems may include a mixing device in which air from the functional duct and/or air duct can be mixed.

The mixing device may be an active or passive mixing device and is used to mix the recirculating exhaust gas and the fresh air outside the turbocharger, so that the composition of the air introduced into the engine is uniform and the peak of pollutants, particulate matter or oxygen I don't have it.

The passive mixing device is configured outside a space in which air can be mixed by itself, wherein the active mixing device actively mixes the air using, for example, a stirring device.

The exhaust gas purification device may be combined with a scavenge air unit.

The available space is better utilized by the combination of both devices.

The scavenging air unit includes at least a cooler and a water mist collector. Exhaust gas purification devices generally include scrubbers and optionally other water mist collectors.

The cooler can be used as a scavenging air cooler and/or an exhaust gas cooler in one device. In this way also the cost of the system is optimized.

This object is also achieved with an engine, preferably a two-stroke engine, comprising an exhaust gas recirculation system as described above.

Such an engine can be flexibly adapted for recirculation of the surrounding exhaust gas.

This object is also achieved with the use of an exhaust gas recirculation system as described above for upgrading engines of marine vessels. By upgrading the engine of the marine vessel with the exhaust gas recirculation system as described above, exhaust gas control can be performed even by a phosphorus vessel that is already in operation.

This object is also achieved, preferably with a method for recirculating exhaust gases in marine vessels, preferably using a system as described above, which method comprises:

a. Compressing air in the first compressor and delivering compressed air to the air inlet of the combustion engine using at least a portion of the exhaust gas of the combustion engine to operate the first turbine of the first turbocharger in the first functional duct. ;

b. Compressing air in the second compressor and delivering compressed air to the air inlet of the combustion engine using at least a portion of the exhaust gas of the combustion engine to operate the second turbine of the second turbocharger in the second function duct. ; And

c. Using a third portion of the exhaust gas of the combustion engine in an air duct to recirculate the exhaust gas and purifying the exhaust gas in an exhaust gas purification unit between the exhaust gas outlet and the air intake of the combustion engine,

d. The amount of exhaust gas passing through the second turbine and the air duct so that both the first inlet valve in the air duct and the second inlet valve upstream of the second turbine take an at least partially open position. Control.

By this exhaust gas recirculation method, even when the engine is fully operating at 100%, it is possible to recirculate and purify a part of the exhaust gas without the need to use an exhaust waste gate.

Thus, the exhaust pollutant value can be obtained directly more easily compared to a system in which engine power must be reduced before exhaust gas purification can be made.

The exhaust gas in the air duct can pass through a preliminary scrubber downstream of the first inlet valve.

By the preliminary scrubber downstream of the first inlet valve, the exhaust gas is purified in advance and the exhaust gas purification efficiency is higher.

The exhaust gas can pass through at least one, preferably two coolers downstream of the inlet valve.

By cooling the exhaust gas, the density of the exhaust gas is lowered and the efficiency of the engine is higher before it is introduced back into the engine. By using two coolers, the amount of exhaust gas subjected to exhaust gas purification can be suitably adjusted.

The exhaust gas may pass through a scrubber downstream of the cooler.

The scrubber purifies the exhaust and may be a combined scrubber as described above.

The compressed air can bypass the scrubber downstream of the cooler.

When exhaust gas purification is not required, the scrubber can be bypassed and preserved, and the service life of the scrubber is prolonged.

The exhaust gas may pass through at least one water mist collector downstream of the cooler and/or downstream of the scrubber.

By using a water mist collector, water is removed from the air or exhaust gases, reducing corrosion in the engine.

The exhaust gas may be mixed with external compressed air before being recirculated into the air intake unit.

Hereinafter, the present invention will be described with reference to the drawings.

1 is a schematic diagram of a first embodiment of the present system.
2 is a schematic diagram of operating conditions for 0 to 100% engine load and 0% exhaust gas recirculation in the first embodiment.
3 is a schematic diagram of operating conditions for 0 to 60% engine load and 10% exhaust gas recirculation in the first embodiment.
4 is a schematic diagram of operating conditions for 60 to 100% engine load and 10% exhaust gas recirculation in the first embodiment.
5 is a schematic diagram of operating conditions for 0 to 100% engine load and 40% exhaust gas recirculation in the first embodiment.
6 is a schematic diagram of a second embodiment of the present system.
7 is a schematic diagram of operating conditions for 0 to 60% engine load and 10% exhaust gas recirculation in the second embodiment.
8 is a schematic diagram of operating conditions for 60 to 100% engine load and 10% exhaust gas recirculation in the second embodiment.
9 is a schematic diagram of operating conditions for 0 to 100% engine load and 0% exhaust gas recirculation in the second embodiment.
10 is a schematic diagram of operating conditions for 0 to 100% engine load and 40% exhaust gas recirculation in the second embodiment.
11 is a cross-sectional view of an engine with space for an exhaust gas recirculation system.
12 is a cross-sectional view of the exhaust gas recirculation system according to the second embodiment in the EGR mode.
13 is a cross-sectional view of an exhaust gas recirculation system according to a second embodiment in a non-EGR mode.
14 is a three-dimensional view of the exhaust gas recirculation system according to the second embodiment in the EGR mode.
15 is a three-dimensional view of an exhaust gas recirculation system according to a second embodiment in a non-EGR mode.
16 is a cross-sectional view of the exhaust gas recirculation system according to the second embodiment in the EGR mode.
17 is a cross-sectional view of an exhaust gas recirculation system according to a second embodiment in a non-EGR mode.
18 is a three-dimensional view of the exhaust gas recirculation system according to the second embodiment in the EGR mode.
19 is a three-dimensional view of an exhaust gas recirculation system according to a second embodiment in a non-EGR mode.
20 is a cross-sectional view of the exhaust gas recirculation system according to the first embodiment in a first mode of operation.
21 is a cross-sectional view of the exhaust gas recirculation system according to the first embodiment in a second mode of operation.
Fig. 22 is a cross-sectional view of Fig. 20 or 21 cut from A-A.
23 is a three-dimensional view of the exhaust gas recirculation system according to the first embodiment in a first mode of operation.
24 is a three-dimensional view of the exhaust gas recirculation system according to the first embodiment in a second mode of operation.

1 shows a schematic diagram of an embodiment of the present system 1. The exhaust gas recirculation system 1 is arranged between the exhaust outlet 2 and the air inlet 3. Exhaust gas from the exhaust outlet 2 partially goes into the first turbocharger 4, where the exhaust gas powers the turbine and fresh air is sucked into the compressor, the compressor being the first turbocharger ( 4) It is driven by the turbine. The compressed air goes to the first cooler 12 and then passes through the first water mist collector 13. Compressed air from the first water mist collector 13 goes to the mixing device 37. Another part of the exhaust gas coming out of the exhaust outlet 2 passes through the second turbocharger 6, where the exhaust gas drives a turbine similar to the first turbocharger 4. A second inlet valve 11 is disposed upstream of the turbine of the second turbocharger 6. The fresh air compressed by the compressor of the turbocharger 6 passes through the first valve 18 and the second cooler 17 and goes to the fourth three-way valve 33. A third water mist collector 29 is disposed downstream of the fourth three-way valve 33. And dry air goes to the mixing device 37. The third part of the exhaust gas exits from the exhaust outlet 2 and passes through the first inlet valve 10 and goes into the third cooler 19. Downstream of the third cooler 19, two three-way valves 22a and 22b are arranged in series. An exhaust gas purification device 8 is disposed downstream of these two three-way valves 22a and 22b. This exhaust gas purification device 8 includes a scrubber 14 and a second water mist collector 15 downstream of the scrubber 14. A pressure increasing device 16 is arranged downstream of the second water mist collector 15. The pressure increasing device in this embodiment is a blower. Air from the blower goes into the mixing device (37). The first three-way valve 22a is connected to the third three-way valve 32 by a connection line 23a. In this embodiment the third three-way valve 32 corresponds to the first valve 18. The second three-way valve 22b is connected to the fourth three-way valve 33 by a connection line 23b. The advantages of this design will be presented in the description in connection with Figs.

FIG. 2 shows a schematic diagram of the operating conditions for 0 to 100% engine load and 0% exhaust gas recirculation of the embodiment shown in FIG. 1. In this mode of operation, both turbochargers 4 and 6 operate at 100% capacity. The first turbocharger 4 is powered by approximately 60% of exhaust gas, and the second turbocharger 6 is powered by approximately 40% of exhaust gas. Coolers 12 and 17 are disposed downstream of both turbo aggregators 4 and 6, respectively. Water mist collectors 13 and 15 are disposed downstream of all coolers 12 and 17. The compressed air from both turbochargers 4 and 6 goes to the mixing device 37 where the air is mixed before going to the air inlet 3. In this mode of operation of the system 1, a first functional duct 5 is formed by a first turbocharger 4, a first cooler 12 and a first water mist collector 13. The second functional duct 7 is formed by a second turbocharger 6, a second cooler 17 and a second water mist collector 15. Upstream of the second turbocharger 6 a second inlet valve 11 is arranged, which can take a position between a fully open position and a fully closed position. Thus, the amount of exhaust gas passing through the second functional duct 7 can be controlled according to the engine load. The position of the second inlet valve 11 is controlled by a control unit (not shown). In this mode of operation the system 1 meets the requirements of the TIER II limit.

3 shows a schematic diagram of the operating conditions for 0 to 60% engine load and 10% exhaust gas recirculation of the first embodiment shown in FIG. 1. In this operating state, the first functional duct 5 formed by the first turbocharger 4, the first cooler 12 and the first water mist collector 13 operates as shown in FIG. . Unlike the operating state of Fig. 2, exhaust gas recirculation takes place in this operating state. Approximately 60% of the exhaust gas passes through the first turbocharger 4 to power the turbocharger 4 and together with it power the first functional duct 5. The remaining exhaust gas passes through an air tuck (9), which air duct has a first inlet valve (10), a third cooler (19), a scrubber (14), a water mist collector (15) and a pressure increasing device (16). It consists of The exhaust gas then goes from the pressure increasing device 16 to the mixing device 37 and is remixed with the fresh air from the first functional duct 5. The three-way valves 22a and 22b allow only exhaust air to flow through the air duct 9. At least the position of the first inlet valve 10 is controlled by a control unit (not shown), and can be controlled between a fully open position and a fully closed position.

4 shows a schematic diagram of the operating conditions for 60 to 100% engine load and 10% exhaust gas recirculation of the first embodiment shown in FIG. 1. In this operating state, both functional ducts 5 and 7 and the air duct 9 operate. As already mentioned in connection with FIGS. 2 and 3, the first functional duct 5 is supplied with approximately 60% of exhaust gas that powers the turbine of the first turbocharger 4, and the first turbocharger ( The compressed air from 4) passes through the first cooler 12 and the first water mist collector 13 and goes to the mixing device 37. The remaining exhaust gas passes through the functional duct 7 and the air duct 9. The configuration of the functional duct 7 corresponds to the functional duct 7 in FIG. 2, and the configuration of the air duct 9 corresponds to the air duct 9 in FIG. 3. In order to control the amount of exhaust gas passing through the air duct 9 and the functional duct 7, the first inlet valve 10 of the air duct 9 and the second inlet valve 11 of the functional duct 7 Is controlled by a control unit (not shown). In this mode of operation, the exhaust gas can be partially recirculated at 100% engine load, thus satisfying the TIER II requirements.

5 shows a schematic diagram of the operating conditions for 0 to 100% engine load and 40% exhaust gas recirculation of the first embodiment shown in FIG. 1. In this embodiment, the second turbocharger 6 (see Fig. 1) is cut off. As already mentioned in connection with FIGS. 2 to 4, the first functional duct 5 is actuated. The air duct 9 extends by the second cooler 17 through all four three-way valves 22a, 22b, 32, 33. Here, the exhaust gas passes from the exhaust outlet 2 through the first inlet valve 10 to the third cooler 19, and then is removed through the connecting line 23a by the three-way valve 22b. It goes to the three-way valve (32) and also passes through the second cooler (17). Downstream of the second cooler 17, the exhaust gas passes through the fourth three-way valve 32 and the connecting line 32b to the three-way valve 22a and then through the exhaust gas purification device 8. This purification device is composed of a scrubber 14 and a second water mist collector 15. The air downstream of the exhaust gas purification device 8 passes through the pressure increasing device 16 and is supplied into the mixing device 37. After mixing with the fresh air from the first functional duct 5, the mixed air passes through the air inlet 3. In this configuration, the system 1 can meet the TIER III criteria at 100% engine load.

6 shows a schematic diagram of a second embodiment of the system 1. The system 1 of the second embodiment comprises a first functional duct 5, which functional duct comprises a first turbocharger 4, a first cooler 12 and a first water mist collector 13. do. The compressed fresh air from the first functional duct 5 enters the mixing device 37 before entering the engine (not shown) at the air inlet 3. Unlike the first embodiment according to FIG. 1, the first functional duct 5 further comprises an exhaust waste gate 39, which exhaust waste gate uses exhaust gas to power the turbocharger. Alternatively, the exhaust gas can be discarded without recirculating the exhaust gas.

The second functional duct 7 comprises a second inlet valve 11, which is arranged upstream of the second turbocharger 6. Compressed air from the second turbocharger 6 passes through the first valve 18 and enters the second cooler 17. Downstream of the second cooler 17, a coupling line valve 20 in the form of a three-way valve is disposed. From this coupling line valve 20, a first line is connected to the scrubber 14 and also runs into the water mist collector 15. Further, a bypass duct 21 from the coupling line valve 20 bypasses the scrubber 14 and is directly connected to the water mist collector 15. The exhaust gas exits from the exhaust outlet 2 and passes through the first inlet valve 10 and enters the cooler 17. So the cooler 17 is a combined cooler for the second functional duct 7 and the air duct 9. Further, the second water mist collector 15 is shared between the air duct 9 and the second functional duct 7. Downstream of the second water mist collector 15, a pressure increasing device 16 is disposed immediately upstream of the mixing device 37. In the mixing device 37, the recirculated exhaust gas and the compressed fresh air are mixed and supplied into the air inlet 3. Further, the second embodiment includes a non-return valve 40 for the case where the pressure of the air from the second water mist collector 15 is sufficient for direct introduction into the air inlet 3. The operation mode of the second embodiment according to this figure will be described with reference to Figs. 7 to 10.

7 shows a schematic diagram of the operating conditions for 0 to 60% engine load and 10% exhaust gas recirculation of the second embodiment according to FIG. 6. The first functional duct 5 is composed of a turbocharger 4, a first cooler 12 and a first water mist collector 14, as described in connection with FIGS. 1 to 6. Approximately 60% of the exhaust gas from the exhaust outlet 2 is supplied into the turbocharger 4 to power the compressor. The remaining exhaust gas passes through the first inlet valve 10 from the exhaust outlet 2 and enters the second cooler 17. Downstream of the second cooler 17, the coupling line valve 20 is in a position to direct the exhaust gas into the blower 16 through the scrubber 14 and the water mist collector. Downstream of the blower 16 the exhaust gas enters the mixing device 37 and then goes to the air inlet 3. This configuration satisfies the TIER II requirements.

Fig. 8 shows a schematic diagram of the operating conditions for 60 to 100% engine load and 10% exhaust gas recirculation of the second embodiment according to Fig. 6; This operating condition corresponds to the operating condition of Fig. 7 except for the exhaust gate 39, which can throw away excess exhaust gas directly into the atmosphere at higher engine loads. The air duct 5 cannot handle the remaining exhaust gas flow at these loads due to the limitations of the turbocharger capability. This configuration satisfies the TIER II standard.

9 shows a schematic diagram of the operating conditions for 0 to 100% engine load and 0% exhaust gas recirculation of the second embodiment according to FIG. 6. Approximately 60% of the exhaust gas comes out of the exhaust outlet 2 and passes through the first turbocharger 4. The compressed air from the turbocharger 4 passes through the first cooler 12 and the first water mist collector 13 and enters the mixing device 37. This first functional duct 5 corresponds to the first functional duct 5 of the first embodiment shown in FIG. 1. Since the exhaust gas is not recirculated in this embodiment, approximately 40% of the exhaust gas is used to power the turbocharger 6. The amount of exhaust gas used to power this turbocharger can be controlled by a second inlet valve 11 controlled by a control unit (not shown). The air compressed by the turbocharger 6 passes through the first valve 18 and goes to the second cooler 17. After the air is cooled in the second cooler 17, the air passes through the coupling line valve 20 and the bypass duct 21 to bypass the purification device. Downstream of the bypass duct 21 the air passes through the second water mist collector 15, and the air can be supplied directly into the air inlet 3 without the need for an additional pressure increase because of its high pressure level. In this mode of operation, the requirements of TIER II can be achieved.

Fig. 10 shows a schematic diagram of the operating conditions for 0 to 100% engine load and 40% exhaust gas recirculation of the second embodiment according to Fig. 6; The first functional duct 5 in this mode of operation corresponds to the first functional duct in FIG. 9. To recirculate the exhaust gas, the exhaust gas exits from the exhaust outlet 2, passes through the first inlet valve 10, enters the cooler 17 and then goes to the coupling line valve 20. The coupling line valve 20 is in a position to direct the exhaust gas to the scrubber 14 and the second water mist collector 15. So, in this embodiment, only the first turbocharger 4 is required. The first inlet valve 10 is controlled by a control unit (not shown). This mode of operation satisfies the TIER III standard.

11 shows a cross-sectional view of an engine 38 with space for an exhaust gas recirculation system 1. The space for the exhaust gas recirculation system 1 must be integrated into the available space of the engine 38. By this integration, the pressure loss in the exhaust gas recirculation system 1 is low. The following design proposals shown in Figs. 12 to 24 are based on the embodiment of Fig. 1 or 6 and are adapted to the usable space shown in Fig. 11.

12 shows a cross-sectional view of the exhaust gas recirculation system according to the second embodiment shown in FIG. 6 in the exhaust gas recirculation mode. The overall design consists of two compartments: an outer compartment, which is a scavenge air compartment 41, and an inner compartment comprising a scrubber 14. Exhaust gas from the second functional duct 7 and/or the air duct 9 passes through the second cooler 17. The coupling line valve 20 downstream of the second cooler 17 consists of two flaps, which are capable of rotating around a rotation point 42. The coupling line valve 20 is in a position that allows exhaust gas recirculation to occur. The exhaust gas passes through the scrubber 14. The direct gas flow through the scavenging air compartment 41 is blocked and the exhaust gas is guided through the scrubber 14 through the venturi nozzle 45. A cleaning liquid spray nozzle 43 is located at the neck of the Venturi nozzle for best particulate removal efficiency. After the exhaust gas flow passes through the venturi nozzle 45, it goes directly upward into the gas scrubber 14 due to the shape of the round scrubber compartment. The drain can be located at the lowest point of the scrubber. The exhaust gas passes through the gas scrubber 14 in an upstream flow. The scrubber 14 is designed as a plate scrubber. The plate may be a simple perforated plate, a seive plate, an impingement plate, a bubble cut plate or a valve plate, or a combination thereof. If the degassing efficiency is not sufficient, additional packing material may be placed between the plates to increase the contact area. At the top of the plate, the cleaning liquid is poured into the gas scrubber 14, and the plate is passed through the plate in a countercurrent flow with respect to the exhaust gas by gravity. Above the scrubber plate, exhaust gases are guided into the longitudinal center of the scrubber compartment. Then, the exhaust gas enters the diagonal downward channel 44 (see Fig. 14). After leaving this channel, the exhaust gas enters the scavenging air compartment 41 and passes through the water mist collector 15 to remove the sprayed cleaning liquid. Then, the purified exhaust gas is passed to the pressure increasing device 16 (not shown) and the mixing device 37 (not shown).

13 shows a cross-sectional view of an exhaust gas recirculation system 1 (shown in FIG. 6) according to a second embodiment in a non-EGR mode. In the absence of exhaust gas recirculation, the flap-shaped coupling line valve 20 is in a position to block access to the scrubber 14. Compressed air coming from the turbocharger 4 (not shown) enters through the cooler 17. Then, the compressed air flows directly through the scavenging air compartment 41 and the water mist collector 15. Downstream of the water mist collector 15, air returns to the air inlet 3 (not shown).

14 shows a three-dimensional view of an exhaust gas recirculation system according to a second embodiment in EGR mode (see FIG. 12).

15 shows a three-dimensional view of an exhaust gas recirculation system according to a second embodiment in a non-EGR mode according to FIG. 13.

16 shows a cross-sectional view of an exhaust gas recirculation system according to a second embodiment in EGR mode. This embodiment corresponds to the embodiment shown in FIG. 12. The only difference lies in the geometry of the flap (corresponding to the coupling line valve 20). The coupling line valve 20 of this embodiment is not joined by one flap as shown in Fig. 12, but includes two separate flaps. The advantage of this design is that less space is required for the flap to rotate. So, in this embodiment, the scrubber compartment can have more space.

17 shows a cross-sectional view of an exhaust gas recirculation system according to a second embodiment in a non-EGR mode. This embodiment is based on the embodiment shown in FIG. 13 and has the same difference as the difference between FIGS. 12 and 16. The coupling line valve 20 requires less space.

18 shows a three-dimensional view of an exhaust gas recirculation system according to a second embodiment in EGR mode. The three-dimensional view of FIG. 18 corresponds to the cross-sectional view of FIG. 16. The coupling line valve 20 comprises two separate flaps and thus requires less space compared to the embodiment of FIG. 14.

19 shows a three-dimensional view of an exhaust gas recirculation system according to a second embodiment in a non-EGR mode. The embodiment of Fig. 19 corresponds to the cross-sectional view of Fig. 17, which differs from the embodiment of Fig. 15 in that the coupling line valve 20 has two separate flaps. The advantage is as already mentioned in connection with FIG. 18.

Fig. 20 shows a cross-sectional view of the exhaust gas recirculation system (shown in Fig. 1) according to the first embodiment in a first mode of operation. The first mode of operation includes a low exhaust gas recirculation rate (approximately 10%) and a reduced compressed air flow from the turbocharger 6 (approximately 30%), or approximately 40% exhaust at 0-25% engine load. Gas recirculation rate or cutoff exhaust gas recirculation. The exhaust gas recirculation system generally includes a scavenging air compartment 41 and an exhaust gas purification device 8. Exhaust gas enters the scrubber 14 from the top. The exhaust gas passes through a special exhaust gas recirculation cooler 19 and optionally a pre-water mist collector. The cooled exhaust gas then enters the scrubber 14. This scrubber 14 consists of two parts, namely a particulate scrubber and a gas scrubber. The particulate scrubber is based on the Venturi scrubber principle. In particular, a plurality of Venturi nozzles (shown in Fig. 22) are disposed horizontally. In order to achieve the highest particulate removal efficiency in the submicron range of about 0.04 μm, a plurality of water spray nozzles 43 (see Fig. 22) are arranged in the venturi nozzle 45. After passing through the venturi nozzle 45, the exhaust gas flow passes upwardly through the plate scrubber 14 due to the round shape (see FIG. 22). In the third water mist collector 29, water droplets are removed from the purified exhaust gas before entering the air inlet 3 (not shown). In addition, the compressed intake air from the turbocharger 6 enters the scavenging air compartment 41 and is cooled in the cooler 17, and water droplets in the compartment are removed by the third water mist collector 29. The exhaust gas then passes through the third water mist collector 15 and enters the air inlet 3 (not shown).

Fig. 21 shows a cross-sectional view of the exhaust gas recirculation system (shown in Fig. 1) according to the first embodiment in a second mode of operation. The second mode of operation includes an exhaust gas recirculation rate of 40%. In this mode of operation, the exhaust gas flows through the third cooler 19 and the second cooler 17 in turn. For this purpose, the flaps 46 and 47 are in a horizontal position. The turbocharger 6 is blocked, so there is no compressed intake air flow. Downstream of the second cooler 17, the exhaust gas goes to the exhaust gas purification device 8. The flap 47 is closed for this purpose.

Fig. 22 is a cross-sectional view of Fig. 20 or 21 cut from A to A, respectively. The exhaust gas enters the special exhaust gas recirculation cooler through the third cooler 19. Then, the exhaust gas passes through a venturi nozzle 45 provided with a spray nozzle 43 having a cleaning liquid. Because of the rounded bottom, the exhaust gas flow is directed upward and the exhaust gas enters the gas scrubber. Due to its round shape, the flushing liquid sprayed in the venturi nozzle can already be separated at the lowest point entering into the drain pipe (not shown) leading to the water treatment system. The large contact area between the gas and the cleaning liquid and the long residence time are important factors in obtaining maximum degassing efficiency. This can be realized with a plate scrubber composed of a plurality of horizontal plates. These plates may be simple perforated plates, sieve plates, impingement plates, bubble cut plates or valve plates, or a combination thereof. If the degassing efficiency is not sufficient, additional packing material may be placed between the plates to increase the contact area. At the top of the plate, the cleaning liquid is poured into the gas scrubber 14, and the plate is passed through the plate in a countercurrent flow with respect to the exhaust gas by gravity. Downstream of the gas scrubber, the exhaust gas passes through a water mist collector (15). And the air goes to the pressure increasing device (not shown).

23 shows a three-dimensional view of the exhaust gas recirculation system according to the first embodiment in the first mode of operation shown in FIG. 20. The scrubber compartment corresponds to the scrubber shown in FIG. 22.

FIG. 24 shows a three-dimensional view of the exhaust gas recirculation system according to the first embodiment in the second mode of operation shown in FIG. 21. The scrubber compartment corresponds to the scrubber shown in FIG. 22.

Claims (32)

As an exhaust gas recirculation system (1) which can be arranged between the exhaust outlet (2) and the air inlet (3) of a two-stroke engine,
A first turbocharger (4) in the first functional duct (5) between the exhaust outlet (2) and the air inlet (3),
A second turbocharger (6) in a second functional duct (7) between the exhaust outlet (2) and the air inlet (3),
An exhaust gas purification device 8 disposed in an air duct 9 disposed between the exhaust outlet 2 and the air inlet 3,
A mixing device 37 used to mix fresh air and recirculating exhaust gas from the turbochargers, and
Control unit for controlling the functional state of the system 1
Including,
The first and second turbochargers 4 and 6 are arranged individually and in parallel,
The air duct 9 is at least partially arranged in parallel with the second functional duct 7, and the control unit is a first arranged in the air duct 9 upstream of the exhaust gas purification device 8 Both the inlet valve 10 and the second inlet valve 11 disposed upstream of the second turbocharger 6 can simultaneously take an at least partially open position so that the first inlet valve 10 and the second inlet valve 11 It is adapted to control the second inlet valve 11, so that the air duct and the second functional duct can be used in parallel,
The first functional duct (5) comprises a first cooler (12) downstream of the first turbocharger, and a first water mist collector (13) downstream of the first cooler (12),
A pressure increasing device (16) is arranged in the air duct (9),
The mixing device 37 is in the congestion device,
-The exhaust gas is mixed with the fresh air from the first functional duct,
-The exhaust gas is mixed with the fresh air from the second functional duct,
-The compressed air from the first turbocharger is arranged to mix with the compressed air from the second turbocharger,
Exhaust gas recirculation system. The method of claim 1,
The exhaust gas recirculation system, wherein the first and second functional ducts (5, 7) are separated and arranged in parallel. The method of claim 1,
The exhaust gas recirculation system, wherein the exhaust gas purification device comprises a scrubber and at least a second water mist collector. The method of claim 3,
The scrubber is an exhaust gas recirculation system, wherein the scrubber is a combined scrubber for gas collection and particulate matter removal. The method of claim 3,
The exhaust gas recirculation system, wherein the pressure increasing device is provided downstream of the second water mist collector. The method of claim 1,
And the second functional duct comprises a second cooler downstream of the second turbocharger. The method of claim 1,
The exhaust gas recirculation system, wherein a first valve is disposed immediately downstream of the second turbocharger. The method of claim 1,
The exhaust gas recirculation system, wherein the air duct includes a third cooler disposed upstream of the exhaust gas purification device. The method of claim 8,
The second cooler and the third cooler are combined coolers disposed downstream of the second turbocharger and downstream of the first valve in the air duct. The method of claim 9,
The exhaust gas recirculation system, wherein the air duct comprises a combined line valve downstream of the combined cooler. The method of claim 10,
The exhaust gas recirculation system, wherein the combined line valve is a three-way valve (33). The method of claim 10,
Wherein the exhaust gas purification device includes a bypass duct between the coupling line valve and the second water mist collector for bypassing the scrubber. The method of claim 8,
Two three-way valves are arranged in series downstream of the third cooler, the air duct is connected to the second functional duct by two connection lines, and the first connection line is a first three-way valve And connected to the second functional duct at a first connection point immediately upstream of the second cooler, and a second connection line starts at a second three-way valve and at a second connection point immediately downstream of the second cooler. An exhaust gas recirculation system connected to the second functional duct, wherein a first check valve is disposed upstream of the first connection point and a second check valve is disposed downstream of the second connection point. The method of claim 13,
The two three-way valves downstream of the third cooler are one valve, exhaust gas recirculation system. The method of claim 13,
The exhaust gas recirculation system, wherein a valve is arranged downstream of the second connection point after the connection point. The method of claim 15,
An exhaust gas recirculation system, wherein a third water mist collector is disposed downstream of the valve after the connection point. The method of claim 8,
Two three-way valves are arranged in series downstream of the third cooler, the air duct is connected to the second functional duct by two connection lines, and the first connection line is a first three-way valve And connected to the second functional duct at a third three-way valve upstream of the second cooler, the second connection line starting at the second three-way valve and immediately downstream of the second cooler. Exhaust gas recirculation system connected to the second function duct in a 4 three-way valve. The method of claim 13,
An exhaust gas recirculation system, wherein a preliminary water mist collector is disposed downstream of the third cooler. The method of claim 1,
An exhaust gas recirculation system, wherein a spare scrubber is disposed downstream of the first inlet valve. The method of claim 17,
An exhaust gas recirculation system, wherein a third water mist collector is disposed downstream of the fourth three-way valve. The method of claim 1,
The exhaust gas recirculation system, wherein the exhaust gas purification device is coupled with a scavenge air unit. A two-stroke engine comprising an exhaust gas recirculation system according to any of the preceding claims. The method according to any one of claims 1 to 21,
The exhaust gas recirculation system is for upgrading an engine of a marine vessel. As a method for recirculating exhaust gas,
a. Compressing air in the first compressor and delivering compressed air to the air inlet of the combustion engine using at least a portion of the exhaust gas of the combustion engine to operate the first turbine of the first turbocharger in the first functional duct. ;
b. Compressing air in the second compressor and delivering compressed air to the air inlet of the combustion engine using at least a portion of the exhaust gas of the combustion engine to operate the second turbine of the second turbocharger in the second function duct. ;
c. Using a third portion of the exhaust gas of the combustion engine in the air duct to recirculate the exhaust gas and purifying the exhaust gas in the exhaust gas purification unit between the exhaust gas outlet and the air intake of the combustion engine; And
d. Mixing recirculating exhaust gas and fresh air from said turbochargers in a mixing device (37);
Including,
The control unit controls the amount of exhaust gas passing through at least the second turbine and the air duct so that both the first inlet valve in the air duct and the second inlet valve upstream of the second turbine are at least partially open. To be able to take a position,
The exhaust gas passes through at least one cooler (17, 19) downstream of the first inlet valve (10), and at least one water mist collector (15) downstream of the at least one cooler (17, 19). , Through 29),
In the mixing device 37,
-The exhaust gas is mixed with the fresh air from the first functional duct,
-The exhaust gas is mixed with the fresh air from the second functional duct,
-The compressed air from the first turbocharger is mixed with the compressed air from the second turbocharger,
Exhaust gas recirculation method. The method of claim 24,
22. A method of recycling exhaust gas, in which a system (1) according to any of the preceding claims is used. The method of claim 24,
The method is used in marine vessels, exhaust gas recirculation method. The method of claim 24,
The exhaust gas recirculation method, wherein the exhaust gas in the air duct passes through a preliminary scrubber downstream of the inlet valve. The method of claim 24,
The exhaust gas recirculation method, wherein the exhaust gas passes through at least two coolers downstream of the first inlet valve. The method of claim 28,
Wherein the exhaust gas is passed through a scrubber downstream of the coolers. The method of claim 28,
Wherein the compressed air bypasses the scrubber downstream of the cooler. The method of claim 28,
The exhaust gas passing through at least one water mist collector downstream of a scrubber downstream of the coolers. The method of claim 24,
The exhaust gas recirculation method, wherein the exhaust gas is mixed with external compressed air before being recirculated into the air intake part.

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