JP5878860B2 - Turbocharged large two-stroke diesel engine with exhaust gas purification function - Google Patents

Description

  The present invention relates to a crosshead turbocharged large two-stroke internal combustion piston engine, which is preferably a diesel engine having an exhaust gas purification system, and in particular, an SCR (Selective Catalytic Reduction) for purifying NOx of exhaust gas. The present invention relates to a crosshead large two-stroke diesel engine having a reactor.

  A crosshead type large two-stroke engine is typically used as a propulsion system for a large ship or a main engine of a power plant. Regulations on emissions, especially on mononitrogen oxide (NOx) levels, have been stricter and are expected to become stricter.

  Public interest in environmental issues is growing rapidly. The International Maritime Organization (IMO) is also discussing emission regulations regarding air pollution in the ocean. The authorities are doing the same in various places around the world. For example, the US Environmental Protection Agency (EPA) proposes to institutionalize what is currently being discussed.

  NOx in the exhaust gas can be reduced by a primary reduction device and / or a secondary reduction device. As a primary method, there is a method that directly affects the combustion process of the engine. How much can actually be reduced depends on the type of engine and the reduction technique, but varies from about 10% to over 80%. The secondary method is a method that uses a device that is not part of the engine itself, and is a means to reduce the emission level without changing the performance of the engine due to optimized fuel settings. is there. The most successful secondary method to date is the SCR (Selective Catalytic Reduction) method, which is a method for reducing NOx. This method is a method of adding ammonia or urea to the exhaust gas before entering the exhaust gas into the catalytic converter, and can reduce the NOx level by 95% or more.

  The SCR reactor comprises multiple layers of catalyst. The volume of the catalyst, and consequently the size of the reactor, varies depending on the activity of the catalyst and the required NOx reduction. The catalyst usually has a monolithic structure, which means that it is composed of a compartment of the catalyst having a large number of parallel channels with catalytic activity on the wall.

  The exhaust gas must have a temperature of at least 280-350 ° C., depending on the sulfur content. That is, in order to efficiently convert NOx into nitrogen and water, the temperature of the exhaust gas at the inlet of the SCR reactor must be high when the sulfur content is high, and the temperature when the sulfur content is low. May be lower.

  The temperature of the exhaust gas on the high pressure side of the turbocharger turbine is approximately 350-450 ° C. Oh, the temperature of the exhaust gas on the turbine low pressure side of the turbocharger is usually approximately 250-300 ° C.

  For this reason, it is preferable to install an SCR reactor on the high pressure side of the turbine of the turbocharger. However, the SCR reactor has a very large number of pipes and containers inside, but when installed on the high pressure side of the turbine, these pipes and containers must be able to withstand a pressure of approximately 4 atmospheres, Moreover, it will be exposed to temperature changes from 20 ° C to 400 ° C. For this reason, there are many complicated problems in the configuration in which the SCR reactor is installed on the high pressure side of the turbine. The expansion and contraction due to temperature causes a big design problem.

  It is very important to correctly add a reducing agent such as ammonia or urea. This is because if the amount added is too large, ammonia slip occurs, and if the amount added is too small, the reduction amount of NOx decreases and a large amount of NOx is released to the environment. Furthermore, adding the appropriate urea corresponding to the NOx present in the exhaust gas is not important at the average level, but also at the short-term level. The meaning is that short-term fluctuations in urea should also be avoided, as short-term fluctuations in the input yield the above-mentioned undesirable results. The reducing agent and the exhaust gas should be mixed correctly. An engine may be operated in the range of 10% to 100% of its continuous maximum output, and therefore the change in the amount of reducing agent to be charged must be wide.

  Because of this background, existing SCR systems typically use sophisticated but expensive dispensing systems. This spraying system can uniformly spray ammonia and urea in the flow of exhaust gas. Further, the existing SCR system uses a dedicated unit called a mixing unit so that sufficient mixing is performed on the downstream side. This is usually quite large. This mixing unit results in an overall head loss (pressure loss) of the exhaust system, which is equivalent to reducing the efficiency of the turbocharger. Such a loss of efficiency of the turbocharger is unacceptable from the viewpoint of fuel efficiency. Furthermore, pressure loss also limits the availability of power turbines driven by bypassed exhaust gas flows (for waste heat utilization).

  Under such background, it is an object of the present invention to provide an engine having an SCR reactor, which overcomes or at least reduces the above-mentioned problems.

  The above object is achieved by the following engine. The engine is a large stroke uniflow diesel engine having a crosshead: a plurality of cylinders arranged in series; a turbine driven by exhaust gas and a compressor driven by the turbine; An exhaust gas receiver extending along a row of the plurality of cylinders, wherein the cylinder is connected to the cylinder via an exhaust duct that guides a high-speed exhaust gas jet to a cavity inside the exhaust gas receiver. An exhaust gas receiver connected and having an outlet; a selective catalytic reduction reactor provided outside the exhaust gas receiver, the inlet connected to the outlet of the exhaust gas receiver; and the turbine of the turbocharger A selective catalytic reduction reactor having an outlet connected to the inlet of the exhaust; exhaust gas from the reducing agent input point Said reducing agent input point so that a high speed exhaust gas jet flowing from the individual exhaust ducts can cause effective mixing of the reducing agent and the exhaust gas. Is provided upstream of the outlet in the exhaust gas receiver.

  When a cylinder exhaust valve associated with the exhaust duct is opened, an exhaust gas jet is released from the exhaust duct. By arranging the reducing agent charging point upstream of the outlet in the exhaust gas receiver, the energy required for mixing the exhaust gas and the reducing agent can be obtained from the jet. Since the energy in the exhaust jet is dissipated in the exhaust gas receiver anyway, the mixing of the reducing agent and the exhaust gas can be performed without using the energy of the main flow of the exhaust gas. It is possible to avoid providing a mixing unit upstream of the SRC. Or it can be at least small and provided in the exhaust gas receiver. Therefore, the installation requirements for the SCR system can be relaxed. The flow resistance due to the mixing unit (which is a flow pressure drop) can also be removed or at least reduced. The urea charge need not be so smooth and may not be continuous. Instead, dosing can be done intermittently and can be controlled by opening / closing the valve. Such control is simple and accurate, and timing control can be accurately performed over a wide range of (urea) delivery times. In this way, arranging the reducing agent charging point in the exhaust gas receiver at a position upstream of the outlet of the exhaust gas receiver realizes a simple injection / administration system.

  In some embodiments, the reducing agent charging point is arranged in the exhaust gas receiver so that at least three exhaust ducts are located in a path between the reducing agent charging point and the outlet of the exhaust gas receiver. Is done.

  By configuring so that there are at least three exhaust ducts in the path from the reducing agent input point to the outlet of the exhaust gas receiver, it is ensured that the reducing agent meets at least one exhaust gas jet before reaching the outlet. .

  In some embodiments, the outlet of the exhaust gas receiver is located at one end in the longitudinal direction, and the reducing agent charging point is located at or near the other end in the longitudinal direction of the exhaust gas receiver.

  Thus, the entire length of the exhaust gas receiver is used to mix the reducing agent with the exhaust gas.

  In some embodiments, the outlet of the exhaust gas receiver is located at a substantially central part in the longitudinal direction of the exhaust gas receiver, and two exhaust gas outlets located at or near one end in the longitudinal direction of the exhaust gas receiver, respectively. A reducing agent charging point is provided,

  This embodiment is advantageous when the outlet is provided near the center in the longitudinal direction of the exhaust gas receiver.

  Some embodiments have an extension that extends from the area of the first or last exhaust duct to provide a quiet area for injecting and atomizing the reducing agent.

  This quiet area is advantageous for atomizing the reducing agent and also for preventing the reducing agent from contacting the inner wall of the exhaust gas receiver.

  The above object is achieved by the following method. This method is a method of introducing a reducing agent into an exhaust gas flow in a large-sized multi-cylinder stroke uniflow diesel engine having a crosshead, wherein: in the engine, a long exhaust gas receiver having a large diameter, A plurality of cylinders are individually connected via an exhaust duct, the exhaust gas receiver has an outlet; the engine has an SCR reactor outside the exhaust gas receiver, and the SCR reactor is a turbocharger. Arranged upstream of the turbine of the feeder and arranged downstream of the exhaust gas receiver: the method injects the reducing agent in spray form into the exhaust gas receiver, wherein the injection The reductant injected may be mixed with a plurality of exhaust gas jets encountered on the way to the exhaust gas receiver. The high-speed gas flow of the exhaust gas jet is utilized for effective mixing of the reducing agent and the exhaust gas; and the reducing agent mixed with the exhaust gas And from the outlet of the exhaust gas receiver to the inlet of the SCR reactor outside the exhaust gas receiver.

  By injecting the reducing agent in the form of a spray into the exhaust gas receiver at a position upstream of the outlet, the energy required to mix the reducing agent with the exhaust gas is obtained from the jet of exhaust gas discharged from the exhaust duct. be able to. The exhaust gas jet is released when the exhaust valve of the cylinder corresponding to the exhaust duct is opened. Anyway, the energy in the exhaust jet is dissipated in the exhaust gas receiver, so that the mixing of the reducing agent and the exhaust gas can be done without using any engine energy. Further, spraying in the exhaust gas receiver upstream of the outlet of the exhaust gas receiver in a spray form realizes a simple injection / administration system.

  Some embodiments include introducing a reducing agent upstream in the exhaust gas receiver such that the reducing agent is mixed by a plurality of exhaust gas jets encountered on the way to the exhaust gas receiving outlet.

  In some embodiments, the reducing agent is introduced from a single point in the exhaust gas receiver.

  In some embodiments, charging of the reducing agent is performed from two reducing agent charging points facing in the longitudinal direction in the exhaust gas receiver.

  The above object is also achieved by the following engine. This engine is a large multi-cylinder stroke uniflow diesel engine with a crosshead: a long exhaust gas receiver having a large diameter; an exhaust gas outside the exhaust gas receiver and downstream of the exhaust gas receiver An SCR reactor provided in the stream; a reducing agent input point for introducing the reducing agent into the exhaust gas stream upstream of the SCR reactor; and a reducing agent delivery system comprising a source (,,) of reducing agent under pressure; An electronic control unit; an on / off type electronic control valve for controlling the flow of the reducing agent to the reducing agent charging point, controlled by a signal from the electronic control unit; And the electronic control unit intermittently supplies the reducing agent to the reducing agent charging point by controlling a valve opening time of the electronic control valve. So as to delivered to configured to control the amount of reducing agent is introduced into the exhaust gas stream.

  In some embodiments, the electronic control unit is associated with the amount of reducing agent delivered to the reducing agent input point based on the amount of reducing agent required depending on the actual operating conditions of the engine. Although configured to control the valve opening time of the electronic control valve, the position of the crankshaft of the engine is not considered in the control.

In some embodiments, the electronic control unit determines the amount of reducing agent to be delivered to the reducing agent input point based on information on NOx content and / or oxygen content in the exhaust gas.

  In some embodiments, the reducing agent injection point is formed by an injection valve having a nozzle for atomizing the reducing agent when the reducing agent is injected into the exhaust gas stream.

  In some embodiments, the reducing agent input point is provided upstream of the outlet of the exhaust gas receiver.

In some embodiments, only one or two reducing agent charging points are provided.

  In some embodiments, only one electronic control valve is provided.

    The above object can also be achieved by the following method. In a large multi-cylinder stroke uniflow diesel engine having a crosshead, this method is a method of introducing a reducing agent into an exhaust gas flow, wherein the engine includes a long exhaust gas receiver having a large diameter; An SCR reactor external to the gas receiver and provided in the exhaust gas stream downstream of the exhaust gas receiver; a reducing agent delivery system comprising a source (,,) of reducing agent under pressure; an electronic control unit; An on / off electronic control valve for controlling the flow of reducing agent to the reducing agent input point upstream of the SCR reactor, controlled by a signal from the electronic control unit; And the method injects the reducing agent in a spray form into the exhaust gas receiver from an injection position of the exhaust gas receiver; Controlling the amount of reducing agent introduced into the exhaust gas flow by intermittently delivering the reducing agent to the reducing agent introduction point by controlling the valve opening time of the electronic control valve; including.

  Further challenges, features, advantages, and properties of engines and methods according to the present disclosure will become apparent from the detailed description that follows.

1 is a front view of a large two-stroke diesel engine according to an exemplary embodiment. FIG. 2 is a side view of the large two-stroke engine of FIG. 1. 2 is a diagrammatic representation of the large two-stroke engine of FIG. FIG. 2 is a detailed view of a cylinder and an exhaust gas receiver of the large two-stroke engine of FIG. 1. It is a detailed view of a cylinder and exhaust gas receiver of a large two-stroke engine according to another embodiment. It is a detailed view of a cylinder and exhaust gas receiver of a large two-stroke engine according to another embodiment. It is a detailed view of a cylinder and exhaust gas receiver of a large two-stroke engine according to another embodiment.

Detailed Description of the Preferred Embodiment

  In the following detailed description section of the specification, the present invention will be described in more detail with reference to exemplary embodiments depicted in the accompanying drawings.

  In the following detailed description, a large two-stroke engine will be described using an exemplary embodiment. FIG. 1-3 shows a turbocharged large-sized low-speed two-stroke diesel engine. This engine includes a crankshaft 42 and a crosshead 43. FIG. 3 is a diagram representation of a turbocharged large low speed two-stroke diesel engine, in which an intake system and an exhaust system are drawn. In this exemplary embodiment, the engine comprises six cylinders 1 in series. A turbocharged large two-stroke diesel engine typically has 5 to 16 cylinders arranged in series. These are supported by the engine frame 45. Such an engine is used, for example, as a main engine of an ocean vessel. It is also used as a fixed engine for turning a generator at a power plant. The total output of such an engine ranges, for example, from 5,000 kW to 110,000 kW.

  This type of engine is a two-stroke uniflow type, has a scavenging port in the lower region of the cylinder 1, and has an exhaust valve 4 in the upper portion of the cylinder 1. The air supply is guided from the air supply receiver 2 to a scavenging port (not shown) of each cylinder 1. When the piston 41 of the cylinder 1 compresses the supply air, fuel is injected, combustion occurs, and exhaust gas is generated. When the exhaust valve 4 is opened, the exhaust gas flows into the exhaust receiver 3 through the exhaust duct 35 corresponding to the cylinder 1, and further passes through the first exhaust pipe 18 including the SCR reactor to the turbine 6 of the turbocharger 5. Further, the exhaust gas flows out through the second exhaust pipe 7 from there. The turbine 6 rotates a compressor 9 provided via an intake port 10 via a shaft 8. The compressor 9 supplies the compressed air supply to the air supply pipe 11 that continues to the air supply receiver 2.

  The air supply to the tube 11 is passed through the intercooler 12 for cooling. As a result, the supply air temperature which was about 200 ° C. when the compressor is discharged is lowered to 36-80 ° C.

  The cooled intake air is guided to an auxiliary blower 16 driven by an electric motor. The auxiliary blower 16 compresses the intake air guided to the air supply receiver 2 in a low load condition or a partial load condition. When the turbocharger is under high load, the compressor 9 can supply sufficient scavenging, so that the auxiliary blower 16 is bypassed by the check valve 15.

  FIG. 3 shows the layout of the SCR system. This system comprises an SCR (Selective Catalytic Reduction) reactor 19. The SCR reactor 19 is outside the exhaust receiver 3 and downstream of the exhaust receiver 3. A reducing agent such as ammonia or urea is added to the exhaust gas before entering the SCR reactor 19. The exhaust gas must be mixed with a reducing agent such as ammonia before passing through the SCR reactor 19. In order to promote the chemical reaction in the SCR reactor 19, the temperature level must be between 200 ° C. and 400 ° C., depending on the sulfur content in the exhaust gas. In this embodiment, the ammonia source is a water-based urea solution.

  In the embodiment depicted in FIG. 3, the tank 26 stores an aqueous solution of urea. A pipe 25 connects the tank 26 to the inlet of the pump 24. Pump 24 is configured to provide a substantially constant pressure. The outlet of the pump 24 is connected to the supply pipe 22, and the supply pipe 22 carries the pressurized component aqueous solution to the injection valve 21 via the electronic control valve 23. The electronic control valve 23 in the present embodiment is an on / off type, but a proportional valve can also be used. The electronic control valve 23 is controlled by a signal from an electronic control unit (processing computer) 50. The electronic control valve may be a hydraulic valve, a pneumatic valve, or may be a valve that operates purely electrically. The injection valve 21 is installed in the exhaust receiver 3. The injection valve 21 is provided with a nozzle having a nozzle hole. By this nozzle hole, the urea aqueous solution injected to the exhaust gas receiver 3 is atomized. The injection valve 21 is configured to perform injection only when the pressure exceeds a threshold value. This is because the injection is performed only when there is sufficient pressure to make the urea aqueous solution mist. A NOx and oxygen analyzer is connected to the second exhaust pipe 7, and the analysis result is transmitted to the electronic control unit 50. The sensor 32 may measure the NOx content of the exhaust gas in the pipe 18 upstream or downstream of the SCR reactor 19 and upstream of the turbocharger 6.

  The amount of reducing agent injected into the exhaust gas is controlled by the electronic control unit 50, which is performed based on the amount of NOx produced under actual operating conditions (load conditions). The relationship of the NOx generation amount with respect to the operation condition (load condition) is derived from the measurement of the NOx generation amount under various operation conditions (load conditions) measured during the test operation of the engine. The amount of reducing agent injected into the exhaust gas is also controlled based on signals from NOx and oxygen analyzers, or based on experimentally determined signals from tables and sensors 32, and all of these. In some cases. The timing for injecting the reducing agent is performed without considering the actual position of the crankshaft 42 of the engine. This is because it is not necessary. Exhaust gas to be mixed with the reducing agent always flows out from the exhaust duct 35, and the exhaust gas always exists in the path from the reducing agent injection point to the outlet 33.

  With reference to FIG. 4, the position of the exhaust gas receiver 3 and the point at which the reducing agent is injected will be described in more detail using a political embodiment. The exhaust gas receiver 3 has a long cylindrical shape and a large cross-sectional area.

  The exhaust gas receiver 3 is provided along the row of cylinders 1 and is provided very close to the upper part of the cylinder 1 where the exhaust valve 4 and the exhaust duct 35 are provided. Each exhaust duct 35 opens to the exhaust gas receiver 3. In many engines, the exhaust valve 3 extends so as to straddle all the cylinders 1 arranged in series in the engine. However, the exhaust gas receiver 3 is often divided into two or more sections in the longitudinal direction. For example, in the case of a very large engine having many cylinders, the exhaust gas receiver 3 Such a configuration may be employed so that the size does not exceed the size compatible with the manufacturing facility. Another reason for dividing the exhaust gas receiver 3 into a plurality in the length direction is when there are a plurality of turbochargers 5. In this case, one divided section of the exhaust gas receiver 3 is assigned to each turbocharger 5.

  Usually, the cross-sectional area of the exhaust gas receiver 3 is equal to or larger than the cross-sectional area of the piston 41 of the engine. As a result, the exhaust gas receiver 3 has a large volume. When the exhaust valve 4 of the cylinder 1 is opened, an exhaust gas jet flows into the exhaust gas receiver 3 through the exhaust duct 35, and the jet may generate pressure fluctuations. The large volume of the exhaust gas receiver 3 makes it possible to mitigate this pressure fluctuation.

  The exhaust gas receiver 3 is provided with an outlet 33. The outlet 33 is connected to the tube 18 and is therefore connected to the SCR reactor 19. For this reason, the exhaust gas collected in the exhaust gas receiver 3 flows to the turbine of the turbocharger 5 through the SCR reactor 19. In this embodiment, the outlet 33 is located at one end in the longitudinal direction of the exhaust gas receiver 3. Therefore, the main flow inside the exhaust gas receiver 3 is unidirectional and directed toward the outlet 33.

  Each cylinder 1 of the engine burns individually according to a predetermined combustion sequence. Accordingly, the corresponding exhaust valves 4 are also opened in the same sequence, and high-speed exhaust gas jets also flow into the exhaust gas receiver 3 through the exhaust duct 35 in the same sequence. The speed of the exhaust gas jet is initially higher than 100 m / s, and becomes slower after the exhaust valve opening phase. In a six-cylinder two-stroke uniflow diesel engine, this means that, on average, approximately two exhaust jets flow into the exhaust receiver 3 at any given time. This is illustrated in FIGS.

  In this embodiment, the point at which the reducing agent is introduced is the injection valve 21, which is provided at the end opposite to the outlet 33 in the longitudinal direction in the exhaust gas receiver. The aqueous urea solution is injected into the exhaust gas receiver 3 like a mist or a jet from the nozzle hole of the injection valve 21. The evaporated aqueous urea solution enters the exhaust gas receiver 3 from the longitudinal end of the exhaust gas receiver 3. There, the gas flow is relatively gentle, forming a highly concentrated area of reducing agent near the reducing agent input point. From this gentle region, the evaporated aqueous urea solution rides on the main flow in the exhaust gas receiver 3 and is carried to the outlet 33 where it is diluted by the exhaust gas being processed. The high temperature of the exhaust gas in the exhaust gas receiver 3 hydrolyzes (thermally decomposes) urea into ammonia gas and an aqueous part (evaporates in the aqueous part of the injected aqueous urea solution). By the time the outlet 33 is reached, the vaporized component aqueous solution and / or ammonia or water gas encounters one or more exhaust gas jets coming from the exhaust duct 35. The high velocity exhaust gas jet causes intense mixing of the exhaust gas with the vaporized elemental aqueous solution and / or ammonia. Thereby, the exhaust gas and the reducing agent are sufficiently mixed before reaching the outlet 33. Thus, the energy required to mix the reducing agent and exhaust gas is due to the exhaust gas jet. In any case, the energy of the exhaust gas jet is mainly lost in the large volume of the exhaust gas receiver 3, so that the mixing of the reducing agent and the exhaust gas is directed to the turbine 6 of the turbocharger 5. This can be done without losing the energy of the exhaust gas flow toward.

  In the present embodiment, the injection valve 21 is located at the extreme end opposite to the outlet 33 in the exhaust gas receiver. However, as will be shown later with respect to other embodiments, the introduction point of the reducing agent does not have to be located at the end of the exhaust gas receiver 3. As long as the reducing agent can meet at least one exhaust gas jet before reaching the outlet 33, the introduction point of the reducing agent may be provided close to the outlet 33.

  The urea aqueous solution may be intermittently injected. This is because there is sufficient time and opportunity for the injected reducing agent to be mixed and dispersed in the exhaust gas receiver 3 with the exhaust gas. Therefore, the timing of reducing agent injection is not so important. This enables the use of a timing-based medicine injection system in which the electronic control unit 50 controls the opening timing of the electronic control valve 23. Since timing control is an accurate process over a wide range of input rates, a relatively simple, accurate and reliable input system is provided. The single point of introduction of the reducing agent helps to simplify the system. Controlling the injection of reducing agent by timing makes it easy to build a system that maintains a virtually constant pressure for each injection event and that can properly atomize the reducing agent at each injection event. To. The timing of the reducing agent injection event is independent of the engine cycle. That is, since the injected reducing agent always meets the exhaust gas jet before reaching the outlet, there is no need to wait for the presence of the exhaust gas jet. However, the timing of injection of the reducing agent may be performed in synchronism with the engine cycle, which has the advantage that the injection can be adapted to the flow field in the exhaust receiver 3 which is easy to move. Therefore, the injection can be performed when the velocity of the gas flow in the vicinity is relatively slow.

  In some embodiments, the reducing agent input system employs a steady flow using control performed by adjusting the injection pressure, or selectively activates a predetermined number of nozzles. You may adopt that.

  The exhaust gas appropriately mixed with the reducing agent flows from the outlet 33 to the inlet of the SCR reactor 19. The exhaust gas appropriately mixed with the reducing agent flows from the inlet of the SCR reactor 19 to the outlet thereof. From the outlet of the SCR reactor 19, the exhaust gas having a reduced NOx content flows to the inlet of the turbine 6 of the turbocharger 5 and then flows to the second exhaust pipe 7. The second exhaust pipe 7 guides the exhaust gas from the outlet of the turbine 6 to the inlet of the silencer 28. The third exhaust pipe 29 guides exhaust gas from the outlet of the silencer 28 to the atmosphere.

  FIG. 5 shows another embodiment. This embodiment is essentially the same as the embodiment of FIG. However, in this embodiment, the outlet 33 is provided at a substantially central portion in the longitudinal direction of the exhaust gas receiver 3. Accordingly, there are two main flows in the exhaust gas receiver 3, each of which flows from the end in the longitudinal direction toward the outlet 33 at the center of the exhaust gas receiver 3, and the flow directions are opposite to each other. . In this embodiment, two reducing agent charging points are provided at the longitudinal ends of the exhaust gas receiver. These two reducing agent charging points are formed by the two injection valves 21. These two injection valves 21 are connected to a single electronic control valve 23. That is, these two injection valves 21 perform injection simultaneously.

  The reducing agent injected by the injection valve 21 at each longitudinal end of the exhaust gas receiver 3 is carried to the outlet 33 by one of the main flows toward the outlet 33. On the way to the outlet 33, the reducing agent meets at least one exhaust gas jet coming from any of the exhaust ducts 35, thereby properly mixing with the exhaust gas before exiting the exhaust gas receiver 3 from the outlet 33. Can be done.

  FIG. 6 also shows another embodiment, which is essentially the same as the embodiment of FIG. However, in this embodiment, the engine is an in-line 5-cylinder engine, and the exhaust gas receiver is extended at the end opposite to the longitudinal end where the outlet 33 is provided. The part extended (or extended part) beyond the last (or first) part of the 35 rows of exhaust ducts is a quiet and gentle area for introducing / injecting reducing agent and atomizing. Are formed in the exhaust gas receiver 3. This region 37 makes it possible for the reducing agent to atomize correctly and not to affect the inner wall of the exhaust gas receiver 3, and to form a large region with a high density of reducing agent in the vicinity of the injection point. About the other point, the injection valve 21 and the injection method of a reducing agent are the same as that of the embodiment of FIG. In FIG. 4, the injection valve 21 is provided at the extreme end of the exhaust gas receiver 3, but the injection valve 21 is disposed in any region where the reducing agent can be atomized in the above-described quiet region 37. Please understand that you may.

  FIG. 7 also shows another embodiment, which is essentially the same as the embodiment of FIG. However, in this embodiment, the charging point of the reducing agent is not provided at the extreme end of the exhaust gas receiver 3. Instead, the reducing agent charging point is provided between the second and third cylinders counted from the opposite side of the outlet 33. Even with this position of the injection valve 21 / reducing agent charging point, there are four cylinder exhaust ducts 35 until the injected reducing agent reaches the outlet 33 of the exhaust gas receiver 3. This ensures that the reducing agent hits at least one exhaust gas jet before reaching the outlet 33. Thus, proper mixing of the reducing agent and exhaust gas is achieved.

  Basically, at least three exhaust ducts 35 need to exist between the input point and the outlet 33 in order for the charged reducing agent to properly mix with the exhaust gas jet before reaching the outlet 33. .

  In the claims, the expressions “comprising” and “having” do not exclude further including (having) other elements and processes. In the claims, a single element does not exclude a configuration having a plurality of elements. The single processing means or unit described in the claims may be a plurality of means having the same function.

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

  Although the present invention has been described in detail for purposes of illustration, these details are presented purely for this purpose and various modifications may be made by those skilled in the art without departing from the scope of the invention. Please understand that. For example, the present invention can be implemented in a large two-stroke engine using exhaust gas recirculation.

Claims (7)

A large two-stroke uniflow diesel engine with a crosshead (41) comprising:
A plurality of cylinders (1) arranged in series;
A scavenging port provided at the bottom of each of the cylinders;
An exhaust valve (4) provided at the top of each of the cylinders;
A turbocharger (5) having a turbine (6) driven by exhaust gas and a compressor (9) driven by the turbine (6) and supplying air to the cylinder (1);
An exhaust gas receiver (3) extending along a row of the plurality of cylinders (1), wherein an exhaust duct (35) extends into a cavity inside the exhaust gas receiver and guides an exhaust gas jet to the cavity. An exhaust gas receiver (3) connected to the cylinder (1) via an outlet and having an outlet (33);
A selective catalytic reduction reactor (19) provided outside the exhaust gas receiver (3), the inlet connected to the outlet (33) of the exhaust gas receiver (3); and the turbocharger (5) A selective catalytic reduction reactor (19) having an outlet connected to the inlet of the turbine (6) of
A source (26) of liquid reducing agent added to the exhaust gas from the reducing agent input point;
Have
The reducing agent charging point is formed by an injection valve (21) having a nozzle for atomizing the liquid reducing agent when the liquid reducing agent is injected into the exhaust gas flow;
The reducing agent injection point is at the exhaust gas receiver (3) so that exhaust gas jets flowing from the individual exhaust ducts can cause effective mixing of the atomized reducing agent and exhaust gas. An engine provided upstream of said outlet (33).   The reducing agent charging point includes at least three exhaust ducts (35) in a path between the reducing agent charging point and the outlet (33) of the exhaust gas receiver (3) in the exhaust gas receiver (3). The engine according to claim 1, wherein the engine is disposed so as to be located.   The outlet (33) of the exhaust gas receiver (3) is located at one end in the longitudinal direction of the exhaust gas receiver (3), and the reducing agent charging point is other than the longitudinal direction of the exhaust gas receiver (3). The engine according to claim 1, which is located at or near an end. The outlet (33) of the exhaust gas receiver (3) is located at the center in the longitudinal direction of the exhaust gas receiver (3),
There are provided two reducing agent charging points located at or near either end in the longitudinal direction of the exhaust gas receiver (3), respectively.
The engine according to claim 1.   The exhaust gas receiver has an extension (37) extending from the region of the first or last exhaust duct (35) to provide a region for injecting and atomizing the reducing agent. Or the engine of 4. In a large multi-cylinder two-stroke diesel engine having a crosshead (41), a method of introducing a reducing agent into an exhaust gas flow,
The engine is a uniflow type having a scavenging port below each cylinder (1) and an exhaust valve (4) above each cylinder (1);
The receiving the exhaust gas (3), the cylinder (1) is, in each individual, which is connected an exhaust gas receiving (3) through an exhaust duct extending into the interior of the cavity (35), receiving the exhaust gas ( 3) has an outlet (33),
The engine has an SCR reactor (19) outside the exhaust gas receiver (3), and the SCR reactor (19) is arranged upstream of the turbine (6) of the turbocharger (5). , Arranged downstream of the exhaust gas receiver (3),
The method
Delivering the liquid reducing agent to an injection valve (21) having a nozzle for atomizing the liquid reducing agent when the liquid reducing agent is injected into the flow of exhaust gas;
Injecting a liquid reducing agent from the injection valve into the exhaust gas receiver (3) in the form of a spray ;
The liquid reducing agent mixed with the exhaust gas flows from the outlet (33) of the exhaust gas receiver to the inlet of the SCR reactor (19) outside the exhaust gas receiver (3); ;
Only including, but be the injection, as the liquid reducing agent is atomised injection, can be mixed with a plurality of exhaust gas jets encountering journey toward the to the outlet of the receiving exhaust gases (33), the performed at a location upstream of the outlet (33), whereby, the gas flow of the exhaust gas jet, effective mixing including that to be utilized to provide the reducing agent exhaust gas, the method.   The reducing agent is introduced from a single point in the exhaust gas receiver (3) or from two injection points that are longitudinally opposed in the exhaust gas receiver (3). The method described in 1.

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