JP6595571B2 - Two-stroke compression ignition engine with large turbocharger with exhaust gas recirculation - Google Patents

Description

  The present invention relates to a two-stroke compression ignition internal combustion engine with a crosshead type large turbocharger including an exhaust gas purification system.

  Crosshead large two-cycle compression ignition internal combustion engines are typically used in large ship propulsion systems or as engines in power plants. In particular, complying with emission regulations regarding nitrogen oxide (NOx) levels has been difficult, but will become increasingly difficult.

  Exhaust gas recirculation is a means known to assist combustion engines in reducing NOx.

  These emission regulations, such as the International Maritime Organization (IMO) Tier II, and especially the Tier III emission standards, are difficult to follow without the use of an exhaust gas recirculation system. Preferably, the exhaust gas recirculation rate is variable.

  Danish Patent No. 177388 discloses a large two-cycle compression ignition internal combustion engine according to the preamble of claim 1.

  Energy systems consisting of engine cylinders and turbochargers must be carefully balanced in all operating conditions. If unbalanced, boundary conditions for the cycle process in the cylinder will be unacceptable and / or the turbocharger compressor will be in a surge or choke condition. The compressor characteristics determine whether the turbocharger is near its maximum efficiency but is operating with sufficient surge margin to ensure the stability of the compressor. A surge margin is required because the operating point of the turbocharger can approach the surge line in the compressor map during transient conditions, such as during fast engine load reduction or abnormal conditions.

  “Balance” is when an engine must provide modes of operation both with and without high pressure exhaust gas recirculation and with a fixed turbocharger component. Remarkably complicated. This is because the exhaust gas recirculation line from the exhaust gas receiver to the scavenging air receiver includes a cooler, which removes a very large amount of energy from the energy system. This energy is “lost” in the ship's central cooler. This energy removal does not occur when operating without effective exhaust gas recirculation. Thus, the balance in the energy system is significantly different during switching from exhaust gas recirculation operation to non-exhaust gas recirculation operation and vice versa.

  Currently, a “balance” is established by using a cylinder bypass from the compressor outlet to the turbine inlet and the turbine bypass. These bypass control techniques are designed to compensate for energy removal in each mode of operation. When operating without exhaust gas recirculation, the turbine bypass reduces the power transmitted to the turbine, and when operating with exhaust gas recirculation, the cylinder bypass increases the power transmitted to the turbine. Together, these means compensate for the effects of an effective or ineffective exhaust gas recirculation line and reduce the flow of scavenging air through the cylinder.

  Therefore, turbo for both operations with and without exhaust gas recirculation while minimizing the need to use a bypass and minimizing energy loss in the exhaust gas recirculation cooler. What is needed is a turbocharged two-stroke compression ignition internal combustion engine in which the charger is balanced.

Danish Patent No. 177388

  In view of the foregoing, it is an object of the present invention to provide a large two-cycle compression ignition internal combustion engine that includes a crosshead that solves or at least reduces the above-described problems.

  The above and other objects are achieved by the features of the independent claims. Further embodiments will be apparent from the dependent claims, the description and the drawings.

  According to a first aspect, a two-stroke compression ignition combustion engine with a large turbocharger including a crosshead, wherein each cylinder comprises a scavenging port and an exhaust valve, via each exhaust valve of the cylinder An exhaust gas receiver connected to the cylinder, a turbocharger, an exhaust gas pipe connecting the outlet of the exhaust gas receiver to a turbine of the turbocharger, a turbocharger compressor of a turbocharger driven by the turbine, and scavenging air A scavenging air pipe connecting the outlet of the turbocharger compressor to the inlet of the receiver, the scavenging air pipe comprising a scavenging air cooler, wherein the scavenging air receiver is connected to the cylinder via a respective scavenging port of the cylinder To connect the scavenging air pipe and recirculate part of the exhaust gas back to the cylinder An exhaust gas recirculation pipe, the exhaust gas recirculation pipe comprising a blower or compressor for returning the recirculated exhaust gas to the cylinder, and scavenging upstream of the scavenging air cooler In an engine with a cylinder bypass pipe and a boiler for bypassing the cylinder by conveying a portion of the hot scavenged air from the air pipe to the turbine of the turbocharger, the engine exhaust gas from the cylinder through the boiler (36). The engine has at least two modes of operation, and the engine, in the first mode of operation, passes the first portion of exhaust gas from the cylinder through the boiler (36). When transported and returned from the boiler (36) to the cylinder through the exhaust gas recirculation pipe And configured to convey a portion of the hot scavenging air from the scavenging air pipe upstream of the scavenging air cooler to the turbine through a bypass pipe, wherein the engine is configured to flow in the second mode of operation through the exhaust gas recirculation pipe. An engine is provided that is configured to prevent and prevent flow through a bypass pipe and to convey a first portion of exhaust gas conveyed through the boiler from the boiler to the turbine.

  By including a boiler that removes energy from the exhaust gas in both exhaust and non-exhaust gas recirculation operations, the energy system is balanced in both modes of operation, Do not use turbine bypass for Instead, the energy system uses a boiler, i.e. a high pressure boiler, in parallel with the exhaust gas receiver to remove energy from the system. The great advantage of high gas temperature and density, resulting in a very efficient heat exchanger or high pressure boiler, providing useful steam that is significantly smaller in size and significantly less costly than conventional boilers after the turbine exit There is. This is particularly useful when the engine is used in a ship where steam is always needed.

  In a first possible embodiment of the first aspect, the engine is configured to convey a second portion of exhaust gas from the cylinder to the turbine without passing through the boiler.

  In a second possible embodiment of the first aspect, the engine comprises an auxiliary blower in the scavenging air tube and the engine is configured to operate the auxiliary blower to maximize boiler steam production. .

  In a third possible embodiment of the first aspect, the first portion of exhaust gas and the second portion of exhaust gas together form a total exhaust gas from the cylinder.

  In a fourth possible embodiment of the first aspect, the engine comprises a boiler tube including a boiler, the boiler tube inlet being connected to the exhaust gas receiver or the exhaust gas tube in a first position.

  In a fifth possible embodiment of the first aspect, the outlet of the boiler pipe is connected to the exhaust gas recirculation pipe in a third position, which is preferably upstream of the blower or compressor. is there.

  In a sixth possible embodiment of the first aspect, the outlet of the boiler pipe is connected to the exhaust gas pipe at a second position downstream of the first position.

  In a seventh possible embodiment of the first aspect, the engine comprises a first control valve in the exhaust gas recirculation pipe.

  In an eighth possible embodiment of the first aspect, the engine comprises a second control valve in the bypass pipe.

  In a ninth possible embodiment of the first aspect, the engine comprises a third control valve between the third position and the position where the exhaust gas recirculation pipe connects to the exhaust gas pipe.

  In a tenth possible embodiment of the first aspect, the exhaust gas recirculation tube comprises an exhaust gas recirculation cooler.

  In an eleven possible embodiment of the first aspect, the splitting of the exhaust gas flow between the boiler and the exhaust gas pipe is controlled according to the desired turbocharger balance.

  In a twelfth possible embodiment of the first aspect, the boiler is integrated into the exhaust gas receiver.

  In a thirteenth possible embodiment of the first aspect, the exhaust gas is used to equalize pressure pulses from the exhausts of the individual cylinders in order to provide a substantially constant pressure at the outlet of the exhaust gas receiver. The gas receiver has a large capacity.

  In a fourteenth possible embodiment of the first aspect, the engine further comprises an auxiliary blower associated with the scavenging air tube to assist the turbocharger at the associated load conditions.

  In a fifteenth possible embodiment of the first aspect, the scavenging air receiver is of high capacity to reduce the pressure surge caused by the inlet flow for the individual cylinders.

  In a sixteenth possible embodiment of the first aspect, the engine is configured to operate the auxiliary blower at all engine load levels with the goal of maximizing boiler steam production. Thus, the use of oil burners or the like to increase steam generation in the low load area of the main engine can be reduced or avoided.

  In a seventeenth possible embodiment of the first aspect, the engine does not comprise a steam boiler on the low pressure side of the turbine.

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

  In the following detailed portion of the disclosure, the present invention will be described in further detail with reference to exemplary embodiments shown in the drawings.

1 is a top view of a front end and one side of a large two-cycle compression ignition turbocharged engine in accordance with an exemplary embodiment. FIG. It is the figure seen from the top which shows the rear-end part and other side part of the engine which are shown in FIG. FIG. 2 is a schematic view of the engine according to FIG. 1, including the intake and exhaust system of the engine according to FIG. 1. 1 is a schematic diagram of a prior art Tier III engine, a prior art intake and exhaust system. FIG. FIG. 5 is a schematic diagram of the prior art Tier III engine shown in FIG. 4 operating in Tier III mode, ie with exhaust gas recirculation. FIG. 5 is a schematic diagram of the prior art Tier II engine shown in FIG. 4 operating in Tier II mode, ie without exhaust gas recirculation. 1 is a schematic diagram of an exemplary embodiment of a Tier III engine including an intake and exhaust system according to the present invention. FIG. FIG. 8 is a schematic view of the Tier III engine shown in FIG. 7 operating in Tier III mode, ie with exhaust gas recirculation. FIG. 8 is a schematic view of the Tier III engine shown in FIG. 7 operating in Tier II mode, ie without exhaust gas recirculation. FIG. 4 is a diagram of another exemplary embodiment of a Tier III engine including an intake and exhaust system according to the present invention. FIG. 4 is a diagram of another exemplary embodiment of a Tier III engine including an intake and exhaust system according to the present invention. FIG. 4 is a diagram of another exemplary embodiment of a Tier III engine including an intake and exhaust system according to the present invention.

  In the following detailed description, a large two-cycle compression ignition internal combustion engine will be described by way of an exemplary embodiment. 1 and 2 show a two-cycle compression ignition internal combustion engine with a large, low speed turbocharger that includes a crankshaft 22 and a crosshead 23 in a view from above. FIG. 3 shows the engine as a schematic including an intake and exhaust system. In this exemplary embodiment, the engine includes six cylinders 1 arranged in a row. Large turbocharged two-stroke diesel engines typically include between 5 and 16 cylinders in a row supported by a cylinder frame 25 supported by an engine frame 24. The engine can be used, for example, as a main engine in an ocean-going vessel or as a stationary engine that operates a generator in a power plant. The total power of the engine can be in the range of, for example, 5,000 to 110,000 kW.

  The engine is a two-cycle uniflow diesel (compression ignition) engine that includes a scavenging port 19 in the form of a piston-controlled port ring in the lower region of the cylinder 1 and an exhaust valve 4 in the upper part of the cylinder 1. Therefore, the flow in the combustion chamber always goes from bottom to top, so the engine is a so-called uniflow type. The scavenging air is passed from the scavenging air receiver 2 to the scavenging air ports 19 of the individual cylinders 1. A reciprocating piston 21 in the cylinder 1 compresses the scavenged air and fuel is injected through two or three fuel valves 27 arranged in the cylinder cover 26. Combustion continues and exhaust gas is produced. When the exhaust valve 4 is opened, the exhaust gas flows through the exhaust conduit 20 associated with the cylinder 1 associated with the exhaust gas receiver 3 and through the exhaust gas pipe 18 to the turbine 6 of the turbocharger 5; The exhaust gas flows away from the turbine 6 through the exhaust pipe 7. The turbine 6 drives a compressor 9 that is supplied through an air inlet 10 through a shaft 8.

  The compressor 9 delivers pressurized scavenging air to a scavenging air tube 11 connected to the scavenging air receiver 2. The scavenged air in the tube 11 passes through an intercooler 12 for cooling the scavenged air. The cooled scavenging air is transmitted to the air supply receiver 2 via an auxiliary blower 16 driven by an electric motor 17 that pressurizes the air supply air at low or partial load conditions. At higher loads, the turbocharger compressor 9 delivers sufficient compressed scavenging air and subsequently the auxiliary blower 16 can be bypassed via the check valve 15.

  The exhaust gas receiver 3 is a large elongate cylindrical container arranged in parallel, very close to the top of the row of cylinders 1. The exhaust gas receiver 3 is large enough to allow the exhaust gas receiver to equalize pressure pulses caused by the periodic inflow of exhaust gas from the individual cylinders 1 at the opening of the exhaust valve 4. . The equalization effect of the exhaust gas receiver 3 provides a substantially constant pressure at the outlet of the exhaust gas receiver 3. A constant pressure at the outlet of the exhaust gas receiver 3 is beneficial because the exhaust gas driven turbocharger 5 or the turbocharger 5 used in a large two-cycle diesel engine benefits from a constant supply pressure.

  From the exhaust gas receiver 3, exhaust gas is guided to the turbine 6 of the turbocharger 5 via the exhaust pipe 18 (a plurality of turbochargers 5 may exist, and a plurality of exhaust gas receivers 3 exist). Can do). The exhaust gas is discarded in the atmosphere downstream of the turbine 6. The turbocharger 5 is a constant pressure turbocharger, that is, the turbocharger 5 is not configured for operation with pressure pulses in the exhaust gas. The turbocharger 5 includes an axial or radial turbine and is configured for exhaust gas temperatures up to about 500 to 550 ° C.

  The turbocharger 5 further includes a compressor 9 that is driven by a turbine 6 via a shaft 8. The compressor 9 is connected to the air intake unit 10. The compressor 9 delivers high-pressure scavenging air to the scavenging air receiver 2 via a scavenging air pipe 11 including a scavenging air cooler 12.

  The scavenging air receiver 2 is a large elongate cylindrical container located in parallel and very close to the bottom of the row of cylinders 1. The scavenging air receiver 2 is large enough to allow the scavenging air receptor 2 to compensate for the pressure drop caused by the periodic outflow of the scavenging air to the individual cylinders 1 at the opening of the scavenging port 19. is there. The compensation effect of the scavenging air receiver 2 provides a substantially constant pressure in the scavenging air receiver 2 so that substantially the same scavenging air pressure is available for each cylinder 1. Utilized because the turbocharger or turbocharger 5 used in a large two-cycle diesel engine is operated using a constant supply pressure and delivers a constant supply pressure, ie to scavenge the individual cylinders 1 Since there are no possible pressure pulses, a constant pressure in the scavenging air receiver 2 is required.

The prior art engine comprises the exhaust gas recirculation system shown in FIG. Exhaust gas recirculation system, for example, in order to lower the combustion temperature, and, in order to reduce it by NO _x emissions, configured to carry a portion of the exhaust gas coming from the cylinder 1 in scavenging air. The exhaust gas recirculation system can be valid or ineffective, or is of a type that operates with varying exhaust gas recirculation rates. The exhaust gas recirculation system includes a pipe 30 extending from the exhaust gas receiver 3 or from the exhaust gas pipe 18 to the scavenging air pipe 11 or to the scavenging air receiver 2. Alternatively, the exhaust gas can be obtained directly from the cylinder 1 via a valve or port (not shown).

  In the prior art shown in FIG. 4, the exhaust gas recirculation pipe 30 connects the exhaust gas pipe 18 to the scavenging air pipe 11. The exhaust gas recirculation pipe 30 branches from the exhaust gas pipe 18 at a position downstream of the exhaust gas receiver 3 and is connected to the scavenging air pipe 11 at a position downstream or upstream of the scavenging air cooler 12.

  The exhaust gas recirculation pipe 30 includes various components. These components include a cleaning device such as a scrubber or filter, a suction blower 32 (driven by an electric motor or by a hydraulic motor), and a first control valve 34.

  The blower 32 and the first control valve 34, i.e. the components of the exhaust gas recirculation pipe 30, are connected to an electronic control unit (not shown). The electronic control unit controls the activity of the exhaust gas recirculation system based on operating conditions and / or based on input from a human operator. Electronic control unit can enable and disable the exhaust gas recirculation system and, if necessary, variably control the exhaust gas recirculation rate, ie the ratio between air and exhaust gas Configured to be.

  The prior art engine includes a cylinder bypass pipe 40 that connects the scavenged air pipe 11 to the exhaust gas pipe 18. One end of the cylinder bypass pipe 40 is connected to the scavenging air pipe 11 at a position downstream of the compressor 9 and upstream of the scavenging air cooler 12. The other end of the cylinder bypass pipe 40 is connected to the exhaust gas pipe 18 at a position downstream of the position where the exhaust gas recirculation pipe 30 is connected to the exhaust gas pipe 18 and upstream of the inlet of the turbine 6. Other connection locations along the exhaust gas pipe 18 are possible.

  The cylinder bypass pipe 40 includes a second control valve 41 that adjusts the flow of the scavenging air from the scavenging air flow path 11 to the exhaust pipe 18 based on, for example, an instruction from an electronic control unit or a human operator. The second control valve 41 has a throttle that is variable and controllable with respect to the flow through the valve.

  Alternatively, the second control valve 4 is an on / off type that is controlled by an electronic control unit or by a human operator. In this embodiment, the electronic control unit is configured to open the second control valve 41 when the exhaust gas recirculation system is enabled, and the second control valve 41 when the exhaust gas recirculation system is disabled. The control valve 41 is configured to be closed.

  The exhaust gas recirculation system can be disabled for various reasons. One of the reasons may be an exhaust gas recirculation system defect or anomaly. Another reason for the ineffectiveness of the exhaust gas recirculation system may be the opportunity to optimize engine fuel consumption in relation to Tier II NOx emission levels. The exhaust gas recirculation rate can vary, for example, between 0% and about 45%.

  When the turbocharger 5 does not properly align with the engine due to surge or choke, the turbocharger 5 does not operate properly or does not operate at all. In typical compressor characteristics, the pressure ratio is plotted as a function of mass flow rate and the speed and efficiency contours of rotation are superimposed. When aligning the turbocharger 5 with the engine, the objective is to place the engine operating point near or within the highest efficiency contour, but with a safety margin against the surge line.

  When the exhaust gas recirculation system changes from the enabled state to the disabled state, the operating state for the turbocharger substantially changes. That is, the turbocharger 5 operates in a state in which the exhaust gas recirculation system is effective (that is, an operation in which the exhaust gas recirculation rate is, for example, between about 20 to 45% and is well matched with the turbocharger 5). In order to be matched to the engine. Without countermeasures, the scavenging air pressure and flow rate will increase by about 25%, which is unacceptable at high engine loads, and can result in turbocharger choke and overspeed, as well as low efficiency, so the exhaust gas recirculation system When is disabled, the turbocharger 5 is not properly aligned.

  Align turbocharger 5 for exhaust gas recirculation engines in accordance with IMO Tier III emission laws or for Tier II engines operating without exhaust gas recirculation (or small exhaust gas recirculation) This is a compromise between the stability (surge margin) of the compressor of the engine 1 and the efficiency / fuel consumption of the compressor / turbocharger. If the turbocharger compressor is aligned with the optimal layout when operating without exhaust gas recirculation, exhaust gas recirculation will reduce the flow through the compressor 9 (engine operating point toward the surge line) There is an unnecessarily large surge margin. Conventional turbochargers or variable turbine area turbochargers do not compromise scavenging air pressure (boost pressure) and engine efficiency, and the flow required to accommodate flow changes when switching between these two modes. Has no range.

  In one embodiment, the compressor 9 of the turbocharger 5 is aligned for exhaust gas recirculation operation and opens the cylinder bypass flow path 40. When switching to the non-exhaust gas recirculation mode, the cylinder bypass passage 40 is closed to prevent the compressor 9 of the turbocharger 5 from being choked, and the increase in flow rate and scavenging air pressure is reduced and compression is performed. Ensure that optimal operating conditions are achieved within the machine characteristics (map). Another effect is that when the cylinder bypass flow path 40 is opened, the air flow through the cylinder 1 is reduced, so that the absolute exhaust gas recirculation mass flow required is required to achieve the expected NOx reduction. It will be smaller. Yet another advantage is that the capacity of the exhaust gas recirculation system itself can be reduced since less suction blower output is required and the amount of exhaust gas being circulated. Accordingly, the electronic control unit can increase the exhaust gas recirculation ratio by increasing the exhaust gas recirculation ratio so that the turbocharger 5 is optimally aligned with the engine at all exhaust gas recirculation ratios used when the engine is operated. It may be configured to increase the opening of the control valve 41 and vice versa.

  The adverse effect of the cylinder bypass flow through the bypass tube 40 is an increase in the heat load on the engine caused by the reduced amount of scavenging gas through the cylinder 1.

  A turbine bypass pipe 50 is provided to blow excess exhaust gas from the exhaust gas pipe 18 during operation without exhaust gas recirculation. The flow through the turbine bypass pipe 50 is controlled by the fifth control valve 51. A steam boiler 52 in the exhaust pipe 7 converts heat in the exhaust gas from the turbine outlet and from the turbine bypass 50 into steam.

  FIG. 5 shows the operating mode of the engine shown in FIG. 4 during operation with exhaust gas recirculation, where both the first control valve 34 and the second control valve 41 are open. For illustration purposes, the control valve is not shown in FIG.

  During operation without exhaust gas recirculation, both the first control valve 34 and the second control valve 41 are closed. This mode of operation is illustrated in FIG. For illustrative purposes, the control valve is not shown in FIG. In an operating mode without exhaust gas recirculation, some of the exhaust gas coming from the cylinder 1 needs to bypass the turbine 6 in order to balance the turbocharger 5. Here, the fifth control valve 51 is opened so that a part of the exhaust gas coming from the cylinder 1 bypasses the turbine 6 via the turbine bypass pipe 50.

  FIG. 7 shows a first exemplary embodiment of the engine. The engine according to this embodiment includes all the features of the prior art engine except for the turbine bypass pipe 50, the fifth control valve 51, and the recirculated exhaust gas cooler 31. In one embodiment, the engine does not include or at least does not require a steam boiler 52 on the low pressure side of the turbine 6, while still being able to produce sufficient steam and still maximally from the burned fuel. Energy can be extracted sufficiently.

  Instead, the engine according to the present embodiment includes a high-pressure boiler 36. The high pressure boiler 36 generates steam that can be used by various consumers related to the engine or engine environment, such as, for example, a ship in which the engine is installed. The high pressure boiler 36 receives a first portion of the total flow rate of exhaust gas from the cylinder 1 through the boiler tube 35. The boiler tube 35 includes a fourth control valve 38.

  In this embodiment, the inlet of the boiler pipe 35 is connected to the exhaust gas receiver 3, and the outlet of the boiler pipe 35 is connected to the exhaust gas recirculation pipe 30. The exhaust gas circulation pipe 30 includes a third control valve 37.

  The control valve can be operated manually or can be connected to an electronic control unit (not shown).

  In the first mode of operation, the engine operates with exhaust gas recirculation. In this mode, the third control valve 37 is closed, the first control valve 34 is opened, and the second control valve 41 is opened. The first mode is shown in FIG. 8 and for the sake of better comprehension, only the effective tubes are shown and the control valves are not shown. In the first mode, the first part of the exhaust gas coming from the cylinder 1 is preferably passed through the boiler tube 35, through the high pressure boiler 36, through the exhaust gas recirculation tube 30 and through the blower 32, preferably a scavenged air cooler. 12 is transported to the scavenging air tube 11 at a position upstream (alternatively, the recirculated exhaust gas may be delivered directly to the scavenging air receiver 2).

  The high temperature scavenging air is conveyed from the scavenging air pipe 11 to the exhaust gas pipe 18 via the bypass pipe 40, thereby bypassing the cylinder 1.

  In the second mode of operation, the engine operates without exhaust recirculation. In this mode, the third control valve 37 is opened, the first control valve 34 is closed, and the second control valve 41 is closed. The second mode is shown in FIG. 9 and only the effective tube is shown and the control valve is not shown to make the drawing more understandable. In the second mode, the first part of the exhaust gas coming from the cylinder 1 is conveyed to the exhaust gas pipe 18 through the boiler pipe 35, through the high pressure boiler 36, through the open third control valve 37, and into the cylinder 1. The second (remaining) part of the exhaust stream coming from. Therefore, all the exhaust gas coming from the cylinder 1 is conveyed to the turbine 6. However, when compared to the prior art, the high pressure boiler 36 removed a portion of the energy and converted the removed portion of the energy into steam, so within the total flow rate of the exhaust gas carrier toward the compressor 6. The amount of energy is lower. Thus, despite the fact that the turbine 6 receives a complete flow of exhaust gas from the cylinder 1, the turbocharger 5 is perfectly engine balanced.

  Preferably, a portion of the total flow rate of the exhaust gas from the cylinder is conveyed to the inlet of the turbine 6 in both operation with exhaust gas recirculation and operation without exhaust gas recirculation.

  FIG. 10 shows a second embodiment which is substantially identical to the first embodiment except that the exhaust gas recirculation pipe 30 is provided with an exhaust gas cooler (scrubber) 39 to be recirculated.

  FIG. 11 shows a third embodiment which is substantially the same as the first embodiment except that the inlet of the boiler tube 35 is directly connected to the cylinder and the outlet of the boiler tube is connected to the exhaust gas pipe 18. Indicates.

  FIG. 12 shows a fourth embodiment that is substantially the same as the first embodiment except that the inlet of the boiler tube 35 is connected to the exhaust gas tube 18.

  In one embodiment, the engine is configured to operate the auxiliary blower 16 at all engine load levels (low, medium, and high engine levels) with the goal of maximizing boiler 36 steam generation. Is done. Thus, the use of an oil burner or the like to increase steam production in the low load area of the main engine can be reduced or avoided.

  In one embodiment (not shown), a high pressure boiler 36 is arranged inside the exhaust gas receiver 3. This significantly reduces the force applied to the boiler component by the exhaust gas pressure. By integrating the high pressure boiler 36 into the exhaust gas receiver, less space is used and the engine is smaller.

  The invention is described herein with reference to various embodiments. However, other variations to the disclosed embodiments can be understood and realized by those skilled in the art in practicing the claimed invention, upon consideration of the drawings, the present disclosure, and the appended claims. . In the claims, the term “comprising” does not exclude other elements or steps, and does not exclude a plurality of configurations that are not expressly stated as being plural. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to obtain an advantage.

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

Claims (13)

A two-stroke compression ignition combustion engine with a large turbocharger including a crosshead (23),
Each cylinder (1) includes a scavenging port (19) and an exhaust valve (4), a plurality of cylinders (1), and the cylinder (1) via each exhaust valve (4) of the cylinder (1) An exhaust gas receiver (3), a turbocharger (5), and an exhaust gas pipe (18) connecting an outlet of the exhaust gas receiver (3) to a turbine (6) of the turbocharger (5) ), The turbocharger compressor (9) of the turbocharger (5) driven by the turbine (6), and the outlet of the turbocharger compressor (9) connected to the inlet of the scavenging air receiver (2) A scavenging air pipe (11), the scavenging air pipe (11) comprising a scavenging air cooler (12), wherein the scavenging air receiver (2) is the scavenging air of each of the cylinders (1). port( 9) with a scavenging air pipe (11) connected to the cylinder (1) through 9) and an exhaust gas recirculation pipe (30) for recirculating a part of the exhaust gas and returning it to the cylinder (1). An exhaust gas recirculation pipe (30), wherein the exhaust gas recirculation pipe (30) comprises a blower (32) or a compressor for returning the recirculated exhaust gas to the cylinder (1); Bypassing the cylinder (1) by conveying a portion of the hot scavenging air from the scavenging air pipe (11) upstream of the scavenging air cooler (12) to the turbine (6) of the turbocharger (5). An engine comprising a cylinder bypass pipe (40) and a boiler (36) for the exhaust gas from the cylinder (1) through the boiler at least a first of the exhaust gas. Configured to convey a portion, wherein the engine has at least two modes of operation, and wherein the engine is configured to transfer the first portion of the exhaust gas in the first mode of operation of the at least two modes of operation. The cylinder (1) is transported through the boiler (36), is transported from the boiler (36) through the exhaust gas recirculation pipe (30) and returned to the cylinder (1), and a part of the high-temperature scavenging air is transported. The scavenging air cooler (12) is configured to convey from the scavenging air pipe (11) upstream of the scavenging air cooler (12) through the cylinder bypass pipe (40) to the turbine (6). In the second mode of operation, the flow through the exhaust gas recirculation pipe (30) is prevented and the cylinder bypass pipe ( 40) is configured to prevent flow through 40 and to convey the first portion of the exhaust gas through the boiler (36) and from the boiler (36) to the turbine (6). And the engine. The engine is configured to convey a second portion of the exhaust gas from the cylinder (1) to the turbine (6) without passing through the boiler (36);
The engine according to claim 1. The scavenging air pipe (11) further comprises an auxiliary blower (16), and the engine is configured to operate the auxiliary blower (16) to maximize steam generation of the boiler (36). ,
The engine according to claim 1 or 2. The first part of the exhaust gas and the second part of the exhaust gas together form a total exhaust gas from the cylinder (1);
The engine according to claim 2. A boiler pipe (35) connected to the boiler (36), the inlet of the boiler pipe (35) being connected to the exhaust gas receiver (3) or the exhaust gas pipe (18) in a first position; Was
The engine according to any one of claims 1 to 4. The outlet of the boiler pipe (35) was connected to the exhaust gas recirculation pipe (30) at a third position;
The engine according to claim 5. The third position is upstream of the blower (32) or the compressor;
The engine according to claim 6. An outlet of the boiler pipe (35) is connected to the exhaust gas pipe (18) at a second position downstream of the first position;
The engine according to any one of claims 5 to 7. The exhaust gas recirculation pipe (30) includes a first control valve (34).
The engine according to any one of claims 1 to 8. The cylinder bypass pipe (40) includes a second control valve (41).
The engine according to any one of claims 1 to 9. A third control valve (37) is provided between the third position and a position where the exhaust gas recirculation pipe (30) connects to the exhaust gas pipe (18);
The engine according to claim 6 or 7. The exhaust gas recirculation pipe (30) comprises an exhaust gas recirculation cooler (39);
The engine according to any one of claims 1 to 11. The boiler (36) is integrated into the exhaust gas receiver (3);
The engine according to any one of claims 1 to 12 .

Images