KR20130064707A - A large turbocharged two-stroke diesel engine with exhaust gas purification - Google Patents

Abstract

PURPOSE: A large size turbo charge two stroke diesel engine having an exhaust gas purification function is provided to connect an exhaust gas accommodating chamber to each cylinder through each exhaust duct, to include a vent, and to flow a reducing agent into the exhaust gas accommodating chamber at a position of a materially upper stream of a vent of the exhaust gas accommodating chamber. CONSTITUTION: A large size turbo charge two stroke diesel engine having an exhaust gas purification function comprises multiple cylinders(1) of serial, a turbocharger, and a selective catalytic reduction reactor in a downstream of an exhaust gas accommodating chamber(3) and an upper stream of the turbocharger. The turbocharger comprises a compressor driven with a turbine for supplying over supplied air to an engine cylinder and an exhaust gas driving turbine. The exhaust gas accommodating chamber is extended along the cylinder and is connected to the cylinder through an exhaust duct(35). The exhaust duct sends a high speed exhaust gas jet to a hollow interior of the exhaust gas accommodating chamber. The exhaust gas accommodating chamber comprises a vent(33). The vent of the exhaust gas accommodating chamber is connected to an inlet port of the selective catalytic reduction reactor. An inlet port of the turbine of the turbocharger and the vent of the selective catalytic reduction reactor are connected. A source of a reducing agent is added to an exhaust gas at a reducing agent influx point. The reducing agent influx point is arranged within the exhaust gas accommodating chamber in order to efficiently mix the reducing agent and the exhaust gas by a high speed exhaust gas jet coming from each exhaust duct in an upper stream of the vent.

Description

LARGE TURBOCHARGED TWO-STROKE DIESEL ENGINE WITH EXHAUST GAS PURIFICATION}

FIELD OF THE INVENTION The present invention relates to a large turbocharged two-stroke internal combustion piston engine of the crosshead type, preferably a diesel engine with an exhaust gas purification system, in particular a selective catalyst for purifying exhaust gases in nitrogen oxides (NO _x ). A large two-stroke diesel engine of the crosshead type with a Selective Catalytic Reduction (SCR) reactor.

Large two-stroke engines of the crosshead type are typically used in propulsion systems of large ships or as prime movers in power plants. Emission requirements have been difficult to meet and increasingly difficult to meet, especially with regard to nitrogen oxides (NO _x ).

The general awareness of environmental issues is growing rapidly. Within the International Maritime Organization (IMO), there is currently a debate on emission limitations in the form of air pollution at sea. In many parts of the world, authorities are taking similar steps. One example is a rule proposed by the Environmental Protection Agency (EPA), which is currently under discussion.

NO _x in the exhaust can be reduced by primary and / or secondary reduction methods. The primary method is a method that directly affects the engine combustion process. The actual degree of reduction depends on the engine type and reduction method, but varies from 10% to 80% or more. The secondary method is a means of reducing the emission level without changing the performance of the engine from the optimized setting of fuel, using equipment that does not form part of the engine itself. The most successful secondary method to date is Selective Catalytic Reduction (SCR) to remove NO _x . This method can reduce NO _x levels by more than 95% by adding ammonia or urea to the exhaust gas before it enters the catalytic converter.

The SCR reactor includes several layers of catalyst. The catalyst volume and, consequently, the size of the reactor depends on the activity of the catalyst and the desired degree of NO _x reduction required. The catalyst is generally a monolithic structure, which means that the catalyst consists of a block of catalyst with a large number of parallel channels, which are walls activated by the catalytic reaction.

The exhaust gas has a temperature of at least 280 to 350 ° C, depending on the fuel sulfur content. At the inlet of the SCR reactor to effectively convert NO _x to N2 and H20, high sulfur content requires high temperature and low sulfur content Low temperature is required.

The exhaust gas on the high pressure side of the turbine of the turbocharger has a temperature of approximately 350 to 450 ° C., while the low pressure side exhaust gas of the turbine of the turbocharger generally has a temperature of approximately 250 to 300 ° C.

As a result, it is advantageous to install an SCR reactor on the high pressure side of the turbine of the turbocharger. However, there are many problems associated with the construction of the SCR reactor on the high pressure side of the turbine due to the fact that such reactors must withstand pressures of approximately 4 bar and contain very large pipes and containers exposed to temperature changes of approximately 20 to 400 ° C. . Thermal expansion and sticking cause many design problems.

Accurate addition of a reducing agent such as ammonia or urea is of great importance because overdose causes ammonia slip while improper dosing does not reduce nitrogen oxides, and thus too much nitrogen oxides are exhausted from the engine. In addition, the correct addition of urea to nitrogen oxides present in the exhaust is important not only at the average level but also at the local level, which means that local fluctuations of the urea must be prevented, which is a local excess. Dosing / improper dosing causes the undesirable effects described above, ie the reducing agent and the exhaust gas must be properly mixed. In addition, the engine is operated in a load range of 10% to 100% of the maximum continuous rating, and the range of the amount of reducing agent that needs to be delivered is therefore wide.

Against this background, current SCR systems generally use complex and therefore expensive spray systems for the uniform distribution of ammonia or urea throughout the exhaust stream, and are generally rather bulky dedicated to ensure sufficient mixing downstream. Use a so-called mixing device. The mixing device also contributes to the total head loss (pressure loss) of the exhaust system, which corresponds to a decrease in turbocharger efficiency. In particular, this loss of turbocharger efficiency is unacceptable in terms of fuel efficiency. This pressure loss also limits the applicability of power turbines driven by exhaust gas bypass streams (waste heat recovery, WHR).

In this context, it is an object of the present application to provide an engine with an SCR reactor which overcomes or at least reduces the above mentioned problems.

This object is achieved by providing a uniflow type large turbocharged two-stroke diesel engine with a crosshead, the engine charging multiple cylinders in series, an exhaust gas powered turbine and an engine cylinder. a turbocharger having a compressor driven by a turbine for supplying air, a long exhaust gas accommodating portion extending along the cylinder and connected to the cylinder through an exhaust duct, the exhaust duct accommodating a high speed exhaust gas jet It is configured to send to the hollow interior, the exhaust gas receiving portion has an outlet, the inlet of the selective catalytic reduction reactor connected to the outlet of the exhaust gas receiving portion and the outlet of the selective catalytic reduction reactor connected to the inlet of the turbine of the turbocharger Equipped with a selective catalytic reduction reactor, reducing agent oil external to the exhaust gas receiving unit A source of reducing agent added to the exhaust gas at the inlet point, wherein the reducing agent inlet point allows exhaust gas upstream of the outlet to enable a high speed exhaust gas jet from each exhaust duct to allow effective mixing of the reducing agent with the exhaust gas It is disposed in the receiving portion.

By placing the reducing agent inlet point in the exhaust gas receiver at a position in the exhaust gas receiver upstream of the outlet, the energy required to mix the reducing agent and the exhaust gas leaves the exhaust duct when the exhaust valve of the cylinder associated with the exhaust duct is opened. From the exhaust jet. The energy in the exhaust jet is somehow dissipated in the exhaust gas receiver such that mixing of the reducing agent and the exhaust gas can be achieved without using an energy main exhaust stream. Mixing devices upstream of the SCR can be avoided or can be constructed and mounted at least smaller in the exhaust gas receiver. Thus, the space requirements of the SCR system are reduced. The flow resistance, which is the loss of flow pressure from the mixing device, is eliminated or at least reduced. It will not be necessary to provide a very smooth and continuous injection of the element. Instead, intermittent injection can be used, and since timing control is an accurate process over a variety of delivery rates, it can be controlled by opening / closing the valve, which can be configured very accurately and easily. Thus, placing the reducing agent inlet point in the exhaust gas receiver at a position in the exhaust gas receiver upstream of the outlet enables a simple injection and injection system.

In one embodiment, the reducing agent inlet point is disposed at a location within the exhaust gas receiving section with at least three exhaust ducts disposed along the path between the reducing agent inlet point and the outlet.

By having at least three exhaust ducts from the reducing agent inlet 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 another embodiment, the outlet is located at one longitudinal end of the exhaust gas receiver and the reducing agent inlet point is disposed at or near the opposite longitudinal end of the exhaust gas receiver.

Thus, the entire length of the exhaust gas receiver is used for mixing the reducing agent and the exhaust gas.

In yet another embodiment, the outlet is located approximately in the middle of the length of the exhaust gas receiver and there are two reducing agent inlet points, each of which is located at or near each longitudinal end of the exhaust gas receiver. do.

This embodiment is advantageous in the exhaust gas accommodating portion when the outlet is somewhere in the middle of the longitudinal direction of the exhaust gas accommodating portion.

In another embodiment, the exhaust gas receiver has an extension past the last or first exhaust duct to provide a quiet area for injecting and spraying the reducing agent.

This quiet area provides a good environment for spraying the reducing agent and preventing the reducing agent from contacting the inner wall of the exhaust gas receiving portion.

The object is also achieved by providing a method of introducing a reducing agent into an exhaust stream in a single-flow large turbocharged two-stroke multi-cylinder diesel engine with a crosshead, the cylinders each being elongated by an exhaust duct. Connected to a large diameter exhaust gas receiver, the exhaust gas receiver having an outlet, the engine being disposed outside the exhaust gas receiver and in an exhaust gas stream upstream of the turbine of the turbocharger and downstream of the exhaust gas receiver. And an SCR reactor, the method injecting a reducing agent as a spray into the exhaust gas receiving portion upstream of the outlet such that the injected reducing agent is mixed by a plurality of exhaust gas jets that meet the way toward the outlet of the exhaust gas receiving portion. Flow of exhaust jets for efficient mixing of And a step of phase to flow from the discharge port, and an exhaust gas mixed with the reducing agent to the exhaust gas of the receiving portion for the inlet of the exhaust gas receiving part of the outer SCR reactor.

By spraying a reducing agent into the exhaust gas receiving portion upstream of the outlet as a spray, the energy required to mix the reducing agent and the exhaust gas comes from the exhaust gas jet leaving the exhaust duct when the exhaust valve of the cylinder associated with the exhaust duct is opened. . The energy in the exhaust jet is somehow dissipated in the exhaust gas receiver such that mixing of the reducing agent and the exhaust gas can be achieved without using energy from the engine. In addition, spraying the reducing agent as a spray into the exhaust gas receiver at an upstream position of the outlet enables a simple injection and injection system.

In one embodiment, the method includes introducing a reducing agent as a spray into the exhaust gas receiving portion such that the reducing agent is mixed by a plurality of exhaust gas jets that meet the way toward the outlet of the exhaust gas receiving portion.

In yet another embodiment, the method includes introducing a reducing agent at a single point in the exhaust gas receiver.

In yet another embodiment, the method includes introducing a reducing agent at two reducing agent inlet points disposed facing each other in the exhaust gas receiving section.

This object is also achieved by providing a single-flow large turbocharged two-stroke multicylinder diesel engine with a crosshead, the engine having a large diameter exhaust gas receiver in an exhaust gas stream downstream of the exhaust gas receiver. And a reducing agent inlet system including an SCR reactor outside the exhaust gas receiving unit, a reducing agent inlet point for introducing a reducing agent into an exhaust gas stream at an upstream position of the SCR reactor, a source of a pressurized reducing agent, an electronic control apparatus, and a reducing agent inlet point An on / off type electronic control valve for controlling the flow of reducing agent to the electronic control valve, wherein the electronic control valve is controlled by a signal from the electronic control device, and the electronic control device controls the opening time of the electronic control valve. By controlling the amount of reducing agent entering the exhaust stream. Air, causing the intermittent transfer of the reducing agent to the reducing agent flowing point.

In one embodiment, the electronic control device is adapted to determine the amount of reducing agent delivered to the reducing agent inlet point based on the amount of reducing agent required at actual operating conditions of the engine and without considering the actual position of the crankshaft of the engine. And to determine the opening timing.

In another embodiment, the electronic control device is further configured to determine the amount of reducing agent delivered to the reducing agent inlet point based on the information on the NOx and / or O2 content of the exhaust gas.

In another embodiment, the reducing agent inlet point is formed by an injection valve with a nozzle for spraying the reducing agent when the reducing agent is injected into the exhaust stream.

In another embodiment, the reducing agent inlet point is upstream of the outlet of the exhaust gas receiver.

In another embodiment there are only one or two reducing agent inlet points.

In another embodiment, there is only one electronic control valve.

The object is also achieved by providing a method for introducing a reducing agent into an exhaust stream in a single-flow large turbocharged two-stroke multi-cylinder diesel engine with a crosshead, the engine comprising a long, large diameter exhaust gas receiver, Reductant delivery system comprising a source of pressurized reducing agent, an SCR reactor in an exhaust gas stream downstream of the exhaust gas receiver and outside the exhaust gas receiver, an electronic control device, a flow of reducing agent upstream of the SCR reactor to a reducing agent inlet point And an electronic control valve of an on / off type for controlling the pressure, the electronic control valve being controlled by a signal from the electronic control device, the method injecting a reducing agent as a spray into the exhaust gas receiving portion at the injection position. And controlling the opening time of the electronic control valve. Injecting an amount of reducing agent into the rim to cause intermittent delivery of the reducing agent to the reducing agent inlet point.

Further objects, features, advantages and characteristics of the engine and method according to the present disclosure will be apparent from the detailed description.

In the following detailed description of the present description, the invention will be described in more detail with reference to the exemplary embodiments shown in the drawings, in which:
1 is a front view of a large two-stroke diesel engine according to one embodiment,
FIG. 2 is a side view of the large two-stroke diesel engine of FIG. 1;
3 is a schematic representation of a large two-stroke engine according to FIG. 1,
4 is a detailed view of the cylinder and exhaust gas receiving portion of the large two-stroke engine of FIG. 1, and
5 to 7 are detailed views of cylinders and exhaust gas receiving portions of a large two-stroke engine according to another embodiment.

In the detailed description that follows, a large two-stroke engine will be described by embodiment. 1-3 show a large low speed turbocharged two-stroke diesel engine with a crankshaft 42 and a crosshead 43. 3 shows a schematic diagram of a large low speed turbocharged two-stroke diesel engine with intake and exhaust system. In this embodiment, the engine has six cylinders 1 in series. Large turbocharged two-stroke diesel engines generally have five to sixteen cylinders in series accommodated by engine frame 45. The engine can be used, for example, as a main engine in marine vessels or as a stationary engine for operating a generator in a power plant. The total output of the engine may range, for example, from 5,000 to 110,000 kW.

The engine is a two-stroke single flow type with a scavenge air port in the lower region of the cylinder 1 and an exhaust valve 4 at the top of the cylinder 1. The boost air is passed from the boost air receiver 2 to the scavenging port (not shown) of each cylinder 1. The piston 41 in the cylinder 1 compresses the boost air, and fuel is injected and burned to produce exhaust gas. When the exhaust valve 4 is open, the exhaust gas flows through the exhaust duct 35 associated with the cylinder 1 to the exhaust gas receiving portion 3 and includes a first exhaust conduit 18 including an SCR reactor 19. Through to the turbine 6 of the turbocharger 5, from which exhaust gas flows out through the second exhaust conduit 7. Through the shaft 8 the turbine 6 drives a compressor 9 which compresses the air supplied through the air inlet 10. The compressor 9 delivers pressurized boost air to the boost air conduit 11 and leads to the boost air receiver 2.

The intake air in the conduit 11 passes through an intercooler 12 that cools the charge air leaving the compressor to a temperature of approximately 200 to 36 degrees Celsius.

The cooled boost air flows through the secondary blower 16 driven by the electric motor 17 which compresses the boost air flow to a low or partial load condition and to the boost air receiver 2. At high loads, the turbocharger compressor 9 delivers sufficient compressed air and then the auxiliary blower 16 is bypassed through the check valve 15.

3 shows a layout of an SCR system. The system comprises a Selective Catalytic Reduction (SCR) reactor 19 outside the exhaust gas receiver 3 and downstream of the exhaust gas receiver 3. Reducing agents such as ammonia or urea are 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, and in order to promote the chemical reaction in the SCR reactor 19, the temperature level is 200 to 400 depending on the sulfur content of the exhaust gas. Should be between ° C. In this embodiment, the source of ammonia is an aqueous urea solution.

In the embodiment shown in FIG. 3, the tank 26 contains an aqueous urea solution. Conduit 25 connects the tank 26 with the inlet of the pump 24. The pump 24 is configured to provide a substantially constant pressure. The outlet of the pump 24 is connected to a supply conduit 22 which delivers the pressurized aqueous urea solution to the injection valve 21 via an electronic control valve 23. In the present embodiment, the electronic control valve 23 is on / off type, but a proportional valve may also be used. The electronic control valve 23 is controlled by a signal from an electronic control device (process computer) 50. The electronic control valve 23 may be a hydraulically or pneumatically driven valve or a purely electronically driven valve. The injection valve 21 is mounted on the exhaust gas receiver 3, and the injection valve 21 has a nozzle having a nozzle hole for spraying it when the aqueous urea solution is injected into the exhaust gas receiver 3. It is provided. The injection valve 21 is configured to initiate the injection when the pressure threshold is exceeded to ensure that the injection is made when there is sufficient pressure to atomize the aqueous urea solution. The NOx and O2 analyzer 32 is connected to the second exhaust conduit 7 and the analysis result is transmitted as a signal to the electronic control device 50. The sensor 32 can also measure the NOx content of the exhaust gas in the conduit 18 upstream or downstream of the SCR reactor 19 as well as downstream of the turbocharger turbine 6.

The amount of reducing agent injected into the exhaust gas is controlled by the electronic control device 50, and generates NOx for the actual driving condition (load) derived from generating NOx under different driving conditions (load) measured when driving the engine test bench. Based on. The amount of reducing agent injected into the exhaust can also be based on both the signal from the NOx and O2 analyzer 32 or the experience table and the signal from the sensor 32. Injection timing of the reducing agent can be made without taking into account the actual position of the crankshaft 42 of the engine, which is from the exhaust duct 35 for mixing of the reducing agent and the exhaust gas on the path of the reducing agent from the injection point to the outlet 33. This is because a jet of exhaust gas is always needed and therefore not required.

Referring now to FIG. 4, the location of the exhaust gas receiver 3 and the reducing agent inlet point is described in more detail with reference to the embodiment. The exhaust gas accommodating part 3 is a large and long cylindrical accommodating part with a large cross-sectional area.

The exhaust gas accommodating part 3 extends along the relatively close cylinder 1 near the top of the cylinder 1 in which the exhaust valve 4 and the exhaust duct 35 are arranged. The exhaust duct 35 leads to the exhaust gas accommodating part 3. In many engines, the exhaust gas receiver 3 extends along all cylinders 1 of the in-line engine. However, it is also common to vertically separate the exhaust gas receiver 3 into two or more parts, for example in a large engine with a very large number of cylinders, the size of the exhaust gas receiver 3 is The purpose is to not exceed the size that can be processed in the manufacturing facility. Another reason for vertically separating the exhaust gas receiver 3 into several parts is that of a plurality of turbochargers 5 each having a portion of the divided exhaust gas receiver 3 associated with a single turbocharger 5. May be present.

In general, the cross-sectional area of the exhaust gas accommodating part 3 is equal to or larger than that of the piston 41 of the engine. The resulting large volume of the exhaust gas receiver 3 is the pressure formed by the exhaust gas jets coming from the exhaust duct 35 of each cylinder 1 when the exhaust valve 4 associated with the cylinder 1 is opened. Ensure the attenuation of the pulses.

The exhaust gas accommodating part 3 has an outlet 33 connecting the conduit 18 and the SCR reactor 19, and the exhaust gas collected in the exhaust gas accommodating part 3 is turbocharged through the SCR reactor 19. It flows to the turbine 6 of the charger 5. In the present embodiment, the outlet 33 is disposed at one longitudinal end of the exhaust gas accommodating portion 3 so that the main direction of the flow inside the exhaust gas accommodating portion 3 is one direction toward the outlet 33. To be.

The cylinders 1 of the engine ignite each in a predetermined ignition order. Accordingly, the exhaust valve 4 is also opened in the same order, and the high velocity exhaust gas jet coming out of the exhaust duct 35 (at least initially 100 m / s later is reduced in the exhaust valve opening step) in the same order of exhaust gas receiving portion. Enter (3). In a six-cylinder two-stroke single-flow diesel engine, this means that there are at least two exhaust jets entering the exhaust accommodation 3 at any time, which are shown in FIGS. 4, 6 and 7. have.

The reducing agent inlet point in this embodiment is the injection valve 21, which is arranged at the longitudinal end of the exhaust gas receiving portion opposite the outlet 33. The aqueous urea solution is injected into the exhaust gas receiver 3 from a hole in the nozzle of the injection valve 21 in the form of a spray or a jet. The vaporized aqueous urea solution enters the exhaust gas receiver 3 at the longitudinal end of the exhaust gas receiver 3, in which the gas flow is relatively calm and forms a high reducing agent concentration near the reducing agent inlet point. The aqueous urea solution vaporized from this calm region is transferred to the outlet 33 in the main direction of the flow in the exhaust gas accommodating part 3 and diluted with the exhaust gas in the process. The high temperature of the exhaust gas in the exhaust gas receiver 3 causes the urea to hydrolyze (pyrolyze) to ammonia gas and the water portion of the injected aqueous urea solution will evaporate. In the path to the outlet 33, the vaporized aqueous urea solution and / or ammonia and water vapor will encounter one or more exhaust gas jets exiting the exhaust duct 35. The high velocity exhaust jets cause intensive mixing of the exhaust gases with the vaporized urea solution and / or ammonia. Thus, by the time the exhaust gas and the reducing agent reach the outlet 33, they are thoroughly mixed. Thus, the energy required to mix the reducing agent and the exhaust gas comes from the exhaust gas jet. The energy in the exhaust gas jet is somehow lost mainly in the large volume of exhaust gas receiver 3, so that the mixing of the reducing agent and the exhaust gas loses energy in the exhaust gas stream destined for the turbine 6 of the turbocharge 5. It can be done without.

In this embodiment, the injection valve 21 is shown disposed at the farthest end of the exhaust gas receiving portion opposite the outlet 33. However, as also shown in connection with other embodiments, it is not necessary to arrange at the point of reducing agent injection at the farthest end of the exhaust gas containing portion 3. The reducing agent injection point can be arranged as close to the outlet 33 as long as it is ensured that the reducing agent meets at least one exhaust gas jet on the way to the outlet 33.

The reducing agent (aqueous urea solution) may be intermittently sprayed because there is sufficient time and opportunity for the injected reducing agent to be mixed and evenly distributed with the exhaust gas in the exhaust gas receiving portion 3. Therefore, the timing of reducing agent injection is not critical. This enables the use of a dose injection system based on a tie in this embodiment by an electronic control device 50 which controls the operating time of the electronic control valve 23. Thus, because timing control is an accurate process over various transfer rates, a relatively simple, accurate and reliable injection system is provided. The fact that a single reducing agent inlet point is sufficient also simplifies the system. The fact that the reducing agent injection is controlled by this timing provides a system that can maintain a substantially constant pressure for the injection and thus ensure that the reducing agent is properly atomized in each injection. The timing of the reducing agent injection is independent of the engine cycle, ie there is no need to wait for the presence or absence of the jet since the injected reducing agent will always meet the exhaust gas jet on the way to the outlet 33. Such, the timing of the injection of the reducing agent can be made in synchronization with the engine cycle, which has the advantage of matching the injection with a temporary flow field inside the exhaust gas receiver 3. Thus, injection can be performed when the local gas flow rate is relatively low.

Instead, the reducing agent injection system can be operated with a stream that continues by adjusting the injection pressure and / or by control performed by selectively operating a certain number of nozzles among the plurality of nozzles.

Exhaust gas suitably mixed with the reducing agent flows from the outlet 33 to the inlet of the SCR reactor 19. In this process, NOx is reduced to N2 and water. From the inlet of the SCR reactor 19, exhaust gas with a reduced amount of NOx flows to the turbine 6 of the turbocharger 5 and then to the second exhaust conduit 7. The second conduit 7 directs the exhaust gas from the outlet of the turbine 6 to a silencer 28. The third exhaust conduit 29 directs the exhaust gas from the muffler 28 to the atmosphere.

5 shows another embodiment. This embodiment is essentially the same as the embodiment of FIG. 4. However, in this embodiment, the said discharge port 33 is arrange | positioned about the middle of the length of the waste gas accommodation part 3. Thus, two opposite main directions of flow, from each longitudinal end of the exhaust gas receiver 3 to the outlet 33 in the middle of the exhaust gas receiver 3 inside the exhaust gas receiver 3 There is this. There are two reducing agent inlet points, each at each of the opposing longitudinal ends of the exhaust gas receiver 3. These two reducing agent inlet points are formed by two injection valves 21. The two injection valves 21 are connected to a single total control valve 23 so that the two injection valves 21 spray at the same time.

The reducing agent injected by the injection valve 21 at each longitudinal end of the exhaust gas accommodating portion 3 is conveyed along any main flow direction toward the discharge port 33. On the way to the outlet 3, the reducing agent will encounter at least one exhaust gas jet exiting either exhaust duct 35 so that the reducing agent is exhaust gas before leaving the exhaust gas receiver 3 through the outlet 33. And will be mixed properly.

FIG. 6 shows another embodiment which is essentially the same as the embodiment of FIG. 4. However, this embodiment of the engine is a five-cylinder in-line engine and the exhaust gas receiver 3 extends at the longitudinal end opposite the longitudinal end where the outlet 33 is arranged. An extension or extension 37 through the last or first exhaust duct 35 provides a calm or quiet area in the exhaust gas receiver 3 for the introduction, injection and spraying of the reducing agent. The quiet area 37 ensures that the reducing agent is properly sprayed and does not collide with the inner wall of the exhaust gas receiver 3 and that a large space with a high concentration of reducing agent is formed near the injection point. Otherwise, the injection valve 21 and the reducing agent injection method are the same as in the embodiment of FIG. 4. In FIG. 4, the injection valve 21 is arranged at the last end of the exhaust gas receiver 3, but the injection valve 21 may be arranged anywhere that allows the reducing agent to be sprayed into the quiet area 37. You must understand that you can.

7 shows another embodiment. The embodiment of FIG. 7 is essentially the same as the embodiment of FIG. 4, but the reducing agent inlet point is not arranged at the last end of the exhaust gas receiver 3. Instead, the reducing agent inlet point is between the second and third cylinders (starting first at the end of the exhaust gas receiving section opposite the end where the outlet 33 is arranged). Due to this position of the injection valve 21 / reducing agent inlet point, there are still four cylinder exhaust ducts 35 to pass through before the injected reducing agent reaches the outlet 33 of the exhaust gas receiver 3, This ensures that the reducing agent is "struck" with the at least one exhaust gas jet before reaching the outlet 33. Thus, proper mixing of the reducing agent and the exhaust gas is ensured.

Basically, there needs to be at least three exhaust ducts 35 between the inlet point and the outlet 33 to ensure that the incoming reducing agent is properly mixed with the exhaust gas before reaching the outlet 33.

The term "comprising" as used in the claims does not exclude other components or steps. The term "one" as used in the claims does not exclude a plurality. A single processor or other apparatus will perform the functions of several means recited in the claims.

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

Although the present invention has been described in detail for purposes of illustration, it is to be understood that these details are for that purpose only and that they may be modified by those skilled in the art without departing from the scope of the present invention. For example, it can also be practiced in large two-stroke engines using exhaust gas recirculation.

1: cylinder 2: charging air receiver
3: exhaust gas accommodating part 4: exhaust valve
5: turbocharger 6: turbine
7: second exhaust conduit 8: shaft
9: compressor 10: air inlet
11: supercharged air conduit 12: intercooler
15: check valve 16: blower
17: electric motor 18: first exhaust conduit
19: SCR reactor 21: injection valve
22: supply conduit 23: electronic control valve
24: pump 25: conduit
26: tank 28: silencer
29: third exhaust conduit 32: NOx and O2 analyzer (sensor)
33: outlet 35: exhaust duct
37: extension part 41: piston
42: crankshaft 43: crosshead
45: engine frame 50: electronic control unit

Claims (15)

In a uniflow type large turbocharged two-stroke diesel engine with a crosshead 43,
Multiple cylinders (1) in series,
A turbocharger (5) having a compressor (9) driven by an exhaust gas drive turbine (6) and a turbine (6) for supplying boost air to the engine cylinder (1);
An elongated exhaust gas receiver 3 extending along the cylinder 1 and connected to the cylinder 1 through an exhaust duct 35, wherein the exhaust duct 35 receives a high speed exhaust gas jet through the exhaust gas receiver. 3) is configured to send inside the hollow,
The exhaust gas accommodating part 3 has an outlet 33,
The outlet of the selective catalytic reduction reactor 19 connected to the inlet of the selective catalytic reduction reactor 19 connected to the outlet 33 of the exhaust gas accommodating part 3 and the inlet of the turbine 6 of the turbocharger 5 is provided. Equipped with a selective catalytic reduction reactor 19 outside the exhaust gas receiving portion 3,
A source of reducing agent 26 added to the exhaust gas at the reducing agent inlet point,
The reducing agent inlet point is characterized in that the high velocity exhaust gas jet from each exhaust duct is arranged in the exhaust gas receiver 3 upstream of the outlet 33 so as to enable effective mixing of the reducing agent with the exhaust gas. engine. The method of claim 1,
Said reducing agent inlet point is arranged at a position in an exhaust gas receiver (3) with at least three exhaust ducts (35) arranged along the path between the reducing agent inlet point and outlet (33). The method of claim 1,
The exhaust port 33 is located at one longitudinal end of the exhaust gas receiver 3 and the reducing agent inlet point is arranged at or near the longitudinal end opposite the exhaust gas receiver 3. . The method of claim 1,
The outlet 33 is located approximately in the middle of the length of the exhaust gas receiver 3, and there are two reducing agent inlet points, each of which at each longitudinal end of the exhaust gas receiver 3. Or disposed near the engine. The method according to claim 3 or 4,
The exhaust gas receiver is characterized in that it has an extension (37) through the last or first exhaust duct (35) to provide a quiet area for injecting and spraying the reducing agent. In a method of introducing a reducing agent into an exhaust stream in a single-flow large turbocharged two-stroke multi-cylinder diesel engine with a crosshead 43, the cylinders 1 each have an exhaust duct 35. Is connected to a long diameter exhaust gas receiver 3, the exhaust gas receiver 3 has an outlet 33, and the engine is external to the exhaust gas receiver 3 and a turbocharger ( An SCR reactor 19 disposed upstream of the turbine 6 of 5) and in an exhaust gas stream downstream of the exhaust gas receiver 3;
The method mixes by a plurality of exhaust gas jets where the injected reducing agent meets the way toward the outlet 33 of the exhaust gas receiver by spraying the reducing agent as a spray into the exhaust gas receiver 3 at an upstream position of the outlet 33. Using a high velocity flow of the exhaust gas jet for effective mixing of the reducing agent and the exhaust gas and reducing agent mixed with the exhaust gas from the outlet 33 of the exhaust gas accommodating part 3 to the exhaust gas accommodating part 3. Flowing to an inlet of an external SCR reactor (19). The method according to claim 6,
The reducing agent is introduced at a single point in the exhaust gas receiver (3), or the reducing agent is introduced at two reducing agent inlet points arranged in the longitudinal direction in the exhaust gas receiver (3). In a single-flow large turbocharged two-stroke diesel engine with a crosshead,
A large diameter exhaust gas accommodating part 3,
SCR reactor 19 in the exhaust stream downstream of the exhaust gas receiver 3 and outside the exhaust gas receiver 3,
A reducing agent inlet point for introducing a reducing agent into an exhaust stream downstream of the SCR reactor 19,
A reducing agent delivery system comprising a source of pressure reducing agent 24, 25, 26,
Electronic controller 50,
An on / off type electronic control valve 23 for controlling the flow of reducing agent to the reducing agent inlet point, the electronic control valve 23 being controlled by a signal from the electronic control device 50 ,
The electronic control device (50) is configured to control the amount of reducing agent entering the exhaust stream by controlling the opening time of the electronic control valve (23). The method of claim 8,
The electronic control device 5 controls the amount of reducing agent delivered to the reducing agent inlet point based on the amount of reducing agent required at the actual operating conditions of the engine and without considering the actual position of the crankshaft 42 of the engine. An engine configured to determine an opening timing of the valve (23). The method of claim 9,
The electronic control device (50) is further configured to determine the amount of reducing agent delivered to the reducing agent inlet point based on the information on the NOx and / or O2 content of the exhaust gas. The method of claim 8,
The reducing agent inlet point is formed by an injection valve (21) having a nozzle for spraying the reducing agent when the reducing agent is injected into the exhaust stream. The method of claim 8,
The reducing agent inlet point is characterized in that it is upstream of the outlet (33) of the exhaust gas receiver (3). The method of claim 8,
An engine characterized by having only one or two reducing agent inlet points. The method of claim 8,
An engine characterized in that there is only one electronically controlled valve (23). A method of introducing a reducing agent into an exhaust gas stream in a single-flow large turbocharged two-stroke multi-cylinder diesel engine with a crosshead (43), the engine comprising a long, large diameter exhaust gas receiver (3), the exhaust Reducing agent delivery system comprising an SCR reactor 19, a source of pressurized reducing agent 24, 25 in the exhaust stream downstream of the gas receiver 3 and outside of the exhaust gas receiver 3, electronic control. Apparatus 50 and an on / off type electronic control valve 23 for controlling the flow of the reducing agent upstream of the SCR reactor 19 to the reducing agent inlet point, wherein the electronic control valve 23 is Controlled by a signal from the electronic control device 50,
The method comprises injecting a reducing agent into the exhaust gas receiving portion 3 as a spray at the injection position and controlling the amount of reducing agent entering the exhaust gas stream by controlling the opening time of the electronic control valve 23 to reduce the inlet flow. Causing intermittent delivery of the reducing agent to the point.

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