Large two-stroke uniflow scavenging turbocharged internal combustion engine equipped with an SCR reactor, and a system and method for measuring the effectiveness of the SCR reactor.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- EVERLLENCE FILIAL AF EVERLLENCE SE TYSKLAND
- Filing Date
- 2025-08-25
- Publication Date
- 2026-07-24
Smart Images
Figure 0007894989000001 
Figure 0007894989000002 
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Abstract
Description
[Technical Field]
[0001] The matters disclosed in this application (hereinafter referred to as "this disclosure") relate to a crosshead type large turbocharged two-stroke uniflow internal combustion piston engine, and in particular to NO in exhaust gas. x This invention relates to a crosshead-type large turbocharged two-stroke uniflow internal combustion piston engine equipped with an SCR (Selective Catalytic Reduction) reactor that reduces emissions and purifies exhaust gases generated from the engine. [Background technology]
[0002] Large two-stroke uniflow scavenging turbocharged internal combustion crosshead engines are typically used in the propulsion systems of large ships or as prime movers in power plants. The size, weight, and power output of this type of engine are quite different from typical internal combustion engines, placing it in its own distinct class.
[0003] Large two-stroke uniflow scavenging turbocharged internal combustion crosshead engines have been operated on a variety of fuels, such as fuel oils like diesel, fuel gases like natural gas or petroleum gas, and ammonia. x NOx is an undesirable by-product in exhaust gases and has adverse effects on the environment. For this reason, emission regulations for the above types of engines are particularly important for nitrogen oxides (NOx). x Regarding the standards, they have always been strict, and they will only become stricter in the future.
[0004] NO in exhaust gas x NO emissions can be reduced by primary and / or secondary reduction methods. Primary methods directly affect the engine combustion process. The actual degree of reduction varies depending on the type of engine and the reduction method, ranging from 10% to over 80%. Secondary methods use equipment that does not constitute part of the engine itself and are means of reducing exhaust gas levels without changing engine performance from fuel-optimized settings. The most successful secondary method to date is NO reduction by SCR (Selective Catalytic Reduction). xis removed. In this method, by adding a reducing agent such as ammonia or urea to the exhaust gas before it enters the catalytic converter, the NO x level can be reduced by 95% or more. Usually, the reducing agent is injected and atomized into the exhaust system upstream of the SCR reactor or into the SCR reactor. The SCR reactor has multiple catalyst layers. The amount of catalyst, and thus the size of the reactor, depends on the activity of the catalyst and the required NO x reduction degree. The catalyst usually has a monolithic structure and is composed of catalyst blocks with a large number of parallel flow channels, and the walls of the flow channels have catalytic activity.
[0005] When urea is added as a reducing agent to the SCR reactor, nitrogen oxides (NO x ) emitted from the engine are reduced to harmless by-products such as nitrogen (N2) and water vapor (H2O). This process takes place through several stages. [[ID=ll]] 1. Urea injection: Urea (CO(NH2)2) is injected into the exhaust stream before it enters the SCR catalyst chamber. Urea is usually dissolved in water to form an aqueous urea solution (UWS) and is sprayed into the exhaust gas. 2. Thermal decomposition: When the aqueous urea solution enters the high-temperature exhaust stream, it evaporates and decomposes into ammonia (NH3) and isocyanic acid (HNCO) by thermal decomposition. This reaction occurs because the exhaust gas is still at a high temperature (usually 200 °C or higher). 3. Hydrolysis: Isocyanic acid further hydrolyzes to produce ammonia and carbon dioxide (CO2). Through this step, most of the urea is converted to ammonia. Ammonia is the actual reducing agent in the SCR process. 4. Catalytic reaction: Next, ammonia reacts with the nitrogen oxides present in the exhaust gas in the presence of the catalyst. The catalyst is usually made of materials such as vanadium, titanium oxide, zeolite, various base metals, etc., and promotes the reaction without being consumed in the process. The SCR catalyst selectively reduces NO x to nitrogen and water vapor in the presence of oxygen contained in diesel exhaust gas.
[0006] This process reduces NO in the exhaust gas xEffectively reduces levels. The efficiency of the SCR system depends on the exhaust gas temperature and NOx. x It depends on various factors, such as the concentration of the urea, the amount and distribution of the urea solution introduced, and the design and material of the SCR catalyst.
[0007] Thus, the use of selective catalytic reduction (SCR) reactors in internal combustion engines is beneficial for NOx reduction. x It is known as a means of supporting emissions reduction. In the case of large two-stroke internal combustion engines operated as marine engines, maritime authorities such as the IMO (International Maritime Organization) and the EPA (U.S. Environmental Protection Agency) require that for each engine manufactured, NO before and after the SCR reactor x The concentration ratio, or reduction rate, must be accurately recorded during factory testing. These factory tests have stringent requirements and must be conducted under precisely controlled conditions. To determine the reduction rate, the first NO is placed upstream of the SCR reactor. x A sensor is placed downstream of the SCR reactor, and another NO x Sensors are placed. Second NO x NO measured by the sensor x The concentration was measured by the first sensor. x The reduction rate is determined by dividing by the concentration. The resulting reduction rate becomes part of the certification process for each engine manufactured. The sensor used in this test is the same sensor used during engine operation to confirm that the reduction rate of the SCR reactor is high enough to be required for engine certification. Marine engine emissions regulations (such as the IMO Act) require NO at each test point. x The reduction rate is NO x The reduction rate must not differ by more than 5% from the reduction rate specified in the technical file (as set for the relevant engine type in the testbed).
[0008] However, it is known that accurately measuring the reduction rate with these sensors is difficult due to sensor gain errors and offset errors. This inaccuracy leads to the need to implement a safety factor, and consequently, the NO discharged from the cylinder. xThis reduces the maximum allowable limit and decreases the design freedom for optimizing engine performance.
[0009] DK177462B1 discloses a crosshead-type large turbocharged two-stroke diesel engine having multiple cylinders, a turbocharger, and an SCR reactor upstream of the turbocharger and downstream of the exhaust gas receiver. The reducing agent for the SCR reactor is introduced into the exhaust gas upstream of the SCR reactor.
[0010] DK177462B1 discloses a crosshead large turbocharged two-stroke diesel engine having multiple cylinders, a turbocharger, and an SCR reactor upstream of the turbocharger and downstream of the exhaust gas receiver. x The sensor receives exhaust gas upstream of the SCR reactor and another second NO x The sensor receives exhaust gas generated downstream of the SCR reactor.
[0011] CN115726871A is NO during engine operation. x A turbocharging system comprising multiple cylinders that generate an exhaust gas flow containing NO, an exhaust gas drive turbine arranged in the exhaust system, a compressor arranged in the scavenging system that supplies scavenging air to the cylinders, an SCR reactor in the exhaust system, and NO within the SCR reactor x A reducing agent supply system is configured to add a reducing agent to the exhaust gas in order to cause a reaction with NO x The invention discloses a large two-stroke uniflow scavenging turbocharged internal combustion engine equipped with a sensor unit. [Overview of the project]
[0012] The objective is to provide a large two-stroke uniflow scavenging turbocharged internal combustion engine and method that solves or at least mitigates the aforementioned drawbacks.
[0013] The features of the independent claims achieve the aforementioned objectives, as well as other objectives. The dependent claims, specification, and drawings illustrate further implementation forms.
[0014] According to the first aspect, a large two-stroke uniflow scavenging internal combustion engine is provided, which is as follows: NO during engine operation x Multiple cylinders that generate an exhaust gas flow including, A turbocharging system comprising an exhaust gas drive turbine located in the exhaust system and a compressor located in the scavenging system that supplies scavenging air to the cylinder, The SCR reactor is arranged in the aforementioned exhaust system, NO in the aforementioned SCR reactor x To cause this reaction, a reducing agent supply system is configured to add the input reducing agent flow to the exhaust gas, NO in the gas supplied to the inlet x NO configured to generate an output corresponding to the concentration x Sensor unit and The aforementioned NO x A valve system configured to selectively supply exhaust gas originating from either the upstream position of the SCR reactor or the downstream position of the SCR reactor to the inlet of the sensor unit, It is equipped with.
[0015] In an example of the implementation of the first aspect described above, the NO x An electronic control unit is connected to the output of the sensor unit, and the electronic control unit controls the NO x The sensor unit output is configured to adjust the magnitude of the input reducing agent flow supplied to the SCR reactor by the reducing agent supply system.
[0016] In one example of the implementation of the first aspect described above, the electronic control unit uses exhaust gas obtained from an upstream position of the SCR reactor and exhaust gas obtained from a downstream position of the SCR reactor to process the NO x The valve system is configured to control the supply of fluid to the inlet of the sensor unit alternately.
[0017] In one example of the implementation of the first aspect described above, the electronic control unit records the NO when exhaust gas originating downstream of the SCR reactor is supplied to the sensor. x The output of the sensor unit is recorded by the electronic control unit when exhaust gas originating from upstream of the SCR reactor is supplied to the sensor, and the NO x By dividing by the output of the sensor unit, the NO of the SCR reactor is obtained. x It is configured to calculate the return rate.
[0018] NO upstream of the SCR reactor x Concentration and NO downstream of the SCR reactor x By measuring the concentration with the same sensor unit, the reduction rate of the SCR reactor can be determined. x Since the gain error is eliminated when dividing by the concentration, the gain error of the sensor unit is removed.
[0019] In one example of the implementation of the first aspect described above, the electronic control unit calculates NO x The system is configured to perform a comparison between the reduction rate and a reduction rate setting, and to adjust the magnitude of the input reducing agent flow supplied to the SCR reactor by the reducing agent supply system as a function of the result of the comparison.
[0020] In one example of the implementation of the first aspect described above, the valve system is • The upstream position of the SCR reactor and the NO x A first control valve is provided in the flow path between the inlet and the sensor unit, - A second control valve is provided in a pipeline communicating downstream of the SCR reactor, or the first port is connected to the upstream position of the SCR reactor, the second port is connected to the downstream position of the SCR reactor, and the third port is the NO x A 3 / 2-way valve connected to the inlet of the sensor unit, It is equipped with.
[0021] In one example of the implementation of the first aspect described above, the organization is the NOx The exhaust gas supplied to the inlet of the sensor unit is heated, and / or the NO x Adjust the pressure of the exhaust gas supplied to the sensor unit, and / or the NO x It includes a conditioning unit configured to adjust the flow rate of exhaust gas to the inlet of the sensor unit.
[0022] In one example of the implementation of the first aspect described above, the conditioning unit comprises one or more filter elements.
[0023] In one example of the implementation of the first aspect described above, the valve system is part of the conditioning unit.
[0024] In an example of the implementation of the first aspect described above, the NO x The sensor unit has one or more NO x It is equipped with a sensor.
[0025] In an example of the implementation of the first aspect described above, the NO x The sensor unit is one or more NOs x It includes an output processing unit configured to process the output from the sensor.
[0026] In an example of the implementation of the first aspect described above, the NO x The entrance to the sensor unit is the aforementioned NO x It is selectively connected to a zero gas source for calibrating the sensor unit.
[0027] According to the second aspect, a method is provided for operating a large two-stroke uniflow scavenging turbocharged internal combustion engine. This method is During the operation of the aforementioned engine, NO was emitted from multiple cylinders. x To generate an exhaust gas flow that includes: By supplying scavenging air to the cylinder using a turbocharging system that includes an exhaust drive turbine in the exhaust system and a compressor in the scavenging system: NO in the SCR reactor of the aforementioned exhaust systemx To cause this reaction, the reduced agent is added to the exhaust gas: NO x NO in exhaust gas supplied to the sensor unit's inlet x To generate an output corresponding to the concentration: The aforementioned NO x The following is a method for selectively supplying exhaust gas originating from either the upstream or downstream position of the SCR reactor to the inlet of the sensor unit: Includes.
[0028] In an example of the implementation of the second aspect described above, the method is the NO x The method further includes adjusting the magnitude of the input reducing agent flow supplied to the SCR reactor as a function of the output of the sensor unit.
[0029] In an example of the implementation of the second aspect described above, the method involves using the exhaust gas obtained from the upstream position of the SCR reactor and the exhaust gas obtained from the downstream position of the SCR reactor to form the NO x This includes controlling the valve system to alternately supply fluid to the inlet of the sensor unit.
[0030] In one example of the implementation of the second aspect described above, the method is such that when exhaust gas originating downstream of the SCR reactor is supplied to the sensor, the NO x The output of the sensor unit is the NO when exhaust gas originating from upstream of the SCR reactor is supplied to the sensor. x By dividing by the output of the sensor unit, the NO of the SCR reactor is obtained. x This includes calculating the return rate.
[0031] In an example of the implementation of the second aspect described above, the method is: The above calculated NO x The comparison involves comparing the return rate with the set return rate value; As a function of the results of the above comparison, the magnitude of the input reducing agent flow supplied to the SCR reactor is adjusted; Includes.
[0032] In one example of the implementation of the second aspect described above, the method changes the operating conditions of the combustion chamber to reduce the amount of NO generated in the combustion chamber. x This further includes increasing or decreasing it.
[0033] In an example of the implementation of the second aspect described above, the method is: The aforementioned NO x Heating the exhaust gas supplied to the inlet of the sensor unit, and / or The aforementioned NO x Adjusting the pressure of the exhaust gas supplied to the sensor unit, and / or The aforementioned NO x Adjusting the flow rate of exhaust gas to the inlet of the sensor unit. Includes.
[0034] In an example of the implementation of the second aspect described above, the method is the NO x One or more NOs within the sensor unit x This further includes processing the output from the sensor.
[0035] In an example of the implementation of the second aspect described above, the method is the NO x The inlet of the sensor unit is the NO x The further includes selectively connecting the sensor unit to a zero gas source for calibration.
[0036] These and other aspects will become even clearer through the examples and embodiments described below. [Brief explanation of the drawing]
[0037] The following will describe in detail various aspects, embodiments, and implementation examples with reference to the exemplary embodiments shown in the drawings. [Figure 1] This figure shows an overview of a large two-stroke diesel engine, according to an exemplary embodiment, viewed from the front. [Figure 2] Figure 1 shows an overview of the large two-stroke engine as viewed from the rear. [Figure 3] Figures 1 and 2 show a schematic representation of the first embodiment of the large two-stroke engine. An SCR system equipped with an SCR reactor is depicted. [Figure 4] Figures 1 and 2 show a schematic representation of a second embodiment of the large two-stroke engine. An SCR system equipped with an SCR reactor is depicted. [Figure 5] This figure shows one embodiment of a control system for supplying a fixed amount of reducing agent to the engine's SCR reactor. [Modes for carrying out the invention]
[0038] In the following detailed description, the internal combustion engine will be described with reference to the crosshead-type large low-speed two-stroke uniflow scavenging turbocharged internal combustion engine of the embodiment. Note that in some cases, the internal combustion engine may be a different type of engine. The large two-stroke low-speed uniflow scavenging turbocharged internal combustion engine can be a compression-ignition type (i.e., high-pressure type) engine in which fuel is injected near or at top dead center of the piston. Alternatively, it can be a spark-ignition type (i.e., low-pressure type) engine in which the scavenging air is mixed with fuel before or during compression. In the latter case, pilot ignition with an additive (e.g., fuel oil) is usually performed to ensure reliable ignition.
[0039] This disclosure provides a large two-stroke uniflow scavenging turbocharged internal combustion engine. Figure 1 illustrates a turbocharged large low-speed two-stroke diesel engine. This engine has a crankshaft 8 and a crosshead 9. Figures 3 and 4 schematically represent first and second embodiments of the turbocharged large low-speed two-stroke diesel engine, along with their intake and exhaust systems. In both the first and second embodiments, the engine has six cylinders in series. A turbocharged large low-speed two-stroke diesel engine typically has 4 to 14 cylinders arranged in series. These cylinders are supported on a cylinder frame 23. The cylinder frame 23 is supported on an engine frame 11. Such engines can also be used, for example, as main engines in ships or as stationary engines to power generators in power plants. The total output of the engine can be, for example, in the range of 1,000 to 110,000 kW.
[0040] In the first and second embodiments, the engine is a two-stroke uniflow compression-ignition engine, with scavenging ports 18 provided in the lower region of each cylinder liner 1, and an exhaust valve located in the center of the top of the cylinder liner 1. The engine's cylinders are formed by the cylinder liners 1. The engine can operate on a variety of fuels, including marine fuel oil, ethanol, methanol, natural gas, petroleum gas, and ammonia. The engine can also be a dual-fuel engine capable of switching between two different fuels. That is, it can be configured to have one operating mode using a first fuel and another operating mode using a second fuel.
[0041] During engine operation, scavenging air is introduced through the scavenging receiver 2 to the scavenging port 18 of each cylinder 1. The piston 10 reciprocates between bottom dead center (BDC) and top dead center (TDC) in the cylinder liner 1, compressing the scavenging air. Fuel is injected into the combustion chamber in the cylinder liner 1 at or near TDC through a plurality of (high-pressure) fuel valves 49 located in the cylinder cover 22. Combustion occurs following the fuel injection, generating exhaust gas. Each cylinder cover 22 is provided with two or more fuel valves 49. The fuel valves 49 are arranged in the cylinder cover 22 around the exhaust valve 4 located in the center of the cylinder cover 22. The fuel valves 49 receive fuel from the (high-pressure) fuel supply system 30.
[0042] Depending on the variations of the first and second embodiments, a fuel valve 49' is positioned along the cylinder liner 1 (indicated by a dashed line). The fuel valve 49' introduces fuel into the cylinder liner on the way from BDC to TDC, before passing the fuel valve 49'. The piston 10 then compresses the mixture of scavenging air and fuel. Ignition is timed to occur at or near TDC. Ignition is achieved by a spark, laser, injection of igniter, etc. In embodiments with a fuel valve 49', the pressure at the time the fuel is introduced is considerably lower than the pressure at the time the fuel is injected in embodiments where the fuel valve 49 is located in the cylinder cover 22. Therefore, the pressure required for the (low-pressure) fuel supply system 30' to deliver fuel can be considerably lower, and / or a pressure booster, often used in fuel valves 49 located in the cylinder cover 22, may be unnecessary. This is particularly advantageous when using gaseous fuel.
[0043] When the exhaust valve 4 opens, the exhaust flows through the exhaust ducts provided in each cylinder to the exhaust receiver 3, then through the selective catalytic reduction reactor (SCR reactor) 28, through the first exhaust pipe 19, and to the turbine 6 of the turbocharger 5. From there, the exhaust is released into the atmosphere through the second exhaust pipe 25 and the exhaust port 21. The SCR reactor 28 filters out emissions in the exhaust, especially NO xThis reduces emissions. In the embodiment shown in Figure 3, the SCR reactor 28 is located upstream of the turbine 6 of the turbocharger 5, i.e., on the high-pressure side of the turbocharger 5, while in the embodiment shown in Figure 4, the SCR reactor 28 is located downstream of the turbine 6 of the turbocharger 5, i.e., on the low-pressure side of the turbocharger 5.
[0044] The turbine 6 drives the compressor 7 via a shaft. The compressor 9 is supplied with outside air through the air intake 12. The compressor 7 sends the compressed scavenging air to the scavenging pipe 13, which is connected to the scavenging receiver 2. The scavenging air in the scavenging pipe 13 passes through the intercooler 14 to cool the scavenging air.
[0045] The cooled scavenging air passes through an auxiliary blower 16 driven by an electric motor 17. The auxiliary blower 16 compresses the scavenging airflow when the compressor 7 of the turbocharger 5 cannot provide sufficient pressure for the scavenging tank 2, i.e., when the engine is under low or partial load. When the engine is under high load, the compressor 7 of the turbocharger can supply sufficiently compressed scavenging air, so the auxiliary blower 16 is bypassed by a check valve 15 and the electric motor 17 is stopped.
[0046] For each engine cycle, the exact amount of fuel to be administered is injected into cylinder 1 through fuel valves 49 and 49'. In some embodiments, the electronic control unit 50 is configured to calculate the engine load as a function of the amount of fuel administered.
[0047] In some embodiments, the engine is equipped with a tachometer (not shown) for detecting the rotational speed of the crankshaft 8. In such embodiments, the electronic control unit 50 can be configured to determine the output supplied by the engine from the product of the rotational speed and the engine load.
[0048] The exhaust gas generated in cylinder liner 1 contains NO at concentrations too high to be directly released into the atmosphere. x It contains NO in exhaust gas. xThis can be reduced using the SCR reactor 28. In embodiments where the SCR reactor 28 is located on the high-pressure side of the turbocharger 5, the SCR reactor 28 can be made smaller due to the high pressure and temperature. In embodiments where the SCR reactor 28 is located on the low-pressure side of the turbocharger 5, the SCR reactor needs to be made correspondingly larger to achieve the same effect due to the lower temperature and pressure. However, even when the SCR reactor 28 is on the high-pressure side of the turbocharger 5, the size of the SCR reactor 28 is about the same as that of the engine. The advantage of the SCR reactor 28 being on the low-pressure side is that the SCR reactor 28 does not need to withstand high temperature and high pressure.
[0049] In the embodiments shown in Figures 3 and 4, the tank 26 contains an aqueous urea solution or another suitable reducing agent. A reducing agent conduit 25 connects the tank 26 to the inlet of the dosing pump 24 and also connects the outlet of the dosing pump 24 to the reducing agent dosing module 20. The reducing agent dosing module 20 is configured to mix the reducing agent with the exhaust gas. An electronically controlled valve 23 is fluidly positioned between the dosing pump (dosing pump) 24 and the dosing module 20. In this embodiment, the electronically controlled valve 23 is an on / off type, but a proportional valve can also be used. The electronically controlled valve 23 is controlled by a signal from the electronically controlled unit 50. The electronically controlled valve 23 may be a hydraulically or pneumatically operated valve, or a purely electrically operated valve. An injection module 20 is provided in or upstream of the SCR reactor. The injection module 20 may be located in the exhaust gas receiver 3. The injection module 20 preferably includes a nozzle with nozzle holes for atomizing the reducing agent solution when the reducing agent solution is injected into the exhaust gas flow. The electronic control unit 50 is configured to control the flow rate of the reducing agent to the input module 20, for example, by controlling the speed of the dosing pump 24.
[0050] The main difference between the embodiment in Figure 3 and the embodiment in Figure 4 is that the SCR reactor 28 and the reducing agent input module 20 are located on the low-pressure side of the turbocharger 5.
[0051] Marine engine emission regulations (IMO law) include NO at each test point. x The reduction rate is NO x The requirements state that the values should not differ by more than 5% from those specified in the technical file (confirmed for the engine type in question on the testbed). Test points typically correspond to 100% engine load with a weighting factor of 0.2, 75% engine load with a weighting factor of 0.5, 50% engine load with a weighting factor of 0.15, and 25% engine load with a weighting factor of 0.1. The law also requires that NO in exhaust gases... x The level is the ratio of NO g / kWh x Level (specific NO x It is indicated as NO (level). NO is produced in the SCR reactor 28 during engine operation. x The reduction rate must be greater than or equal to the value shown in the technical file. Therefore, the electronic control unit 50 controls the NO of the SCR reactor 28. x The system is configured so that the reduction rate at each operating point is equal to or greater than the value specified in the technical file.
[0052] The electronic control unit 50 is connected to various components of the engine via signal lines (shown by dashed lines) and wirelessly.
[0053] The electronic control unit 50 is NO x It is connected to the output of sensor unit 32. NO x The sensor unit 32 has one or more NO x It includes sensor elements 33 and 34. In the illustrated embodiment, NO x The sensor unit 32 has two NO x It is shown having sensor elements 33, 34. However, to improve accuracy and redundancy, more NO x Sensor elements 33 and 34 may be used. Also, a single NO x It should also be understood that sensor element 33 is sufficient.
[0054] NO xThe sensor elements 33, 34 are made of ceramic elements composed of materials such as zirconia (ZrO2) or titania (TiO2), and are often coated with a catalyst such as platinum. These sensor elements 33, 34 are sensitive to NO x gas. NO x The sensor unit 32 receives the exhaust gas through an inlet. NO x The outlet of the sensor unit 32 is connected to the exhaust outlet 21 through the sensor exhaust pipe 35. When the exhaust gas contacts the sensor elements 33, 34, NO x molecules react on the sensor surface. For example, in a zirconia-based sensor, NO x reacts to the presence of oxygen ions moving within the ceramic. This movement of ions generates a minute current. The sensor elements 33, 34 can be heated to a high temperature (about 500 - 900 °C) using a built-in heater. This heating helps to efficiently cause an electrochemical reaction. The reaction between NO x and the sensor elements 33, 34 generates a measurable electrical signal, typically a voltage or a current. The magnitude of this signal is directly related to the NO x concentration in the exhaust gas (e.g., concentration in ppm units). The raw signal generated by the sensor elements 33, 3 is usually an analog signal. This signal is processed by the internal electronics of the sensor unit 32 (which may include amplification, filtering, and analog-to-digital conversion) and made available for use by the electronic control unit 50. The processed signal is sent to the electronic control unit 50 as an output. This sensor unit output represents the NO x concentration in the exhaust gas.
[0055] The electronic control unit 50 uses this sensor unit output to adjust the amount of reductant supplied to the SCR reactor 28.
[0056] <00,00346>The valves 36, 37 are configured to selectively supply the exhaust gas originating from either an upstream position of the SCR reactor 28 or a downstream position of the SCR reactor 28 to the inlet of the NO x sensor unit 32.
[0057] The electronic control unit 50 is NO x It is connected to the output of sensor unit 32. As shown in Figure 5, NO x The sensor unit 32 has one or more NO x An output processing unit 56 configured to process the outputs from sensors 33 and 34 may be provided. x Sensor unit 32 detects multiple NO x If a sensor element 33 is present, the output processing unit 56 improves accuracy by processing individual NOs x The system may be configured to determine a representative value (average) or mean value of the signals provided by the sensor elements 33 and 34.
[0058] The electronic control unit 50 is NO x The sensor unit 32 is configured to adjust the magnitude of the input reducing agent flow supplied from the reducing agent supply systems 25, 26, and 27 to the SCR reactor 28 as a function of its output.
[0059] The electronic control unit 50 processes the exhaust gas obtained from the upstream position of the SCR reactor 28 and the exhaust gas obtained from the downstream position of the SCR reactor 28, and the NO x The valves 36 and 37 may be configured to be controlled to alternately supply fluid to the inlet of the sensor unit.
[0060] The electronic control unit 50 records NO when exhaust gas originating downstream of the SCR reactor 28 is supplied to the sensor. x The output of the sensor unit was recorded by the electronic control unit 50 when exhaust gas originating from upstream of the SCR reactor 28 was supplied to the sensor. x By dividing by the output of the sensor unit, the NO of the SCR reactor 28 is obtained. x The system may be configured to calculate the reduction rate. This process may be performed by the dosage control algorithm of the electronic control unit 50 shown in Figure 5.
[0061] The electronic control unit 50 calculates NO xA comparison is performed to compare the reduction rate with the reduction rate set value, and the system may be configured to adjust the magnitude of the input reducing agent flow supplied to the SCR reactor 28 by the reducing agent supply systems 24, 25, 26, 27 as a function of the result of the comparison. The reduction rate set value and NO x The comparison with the output of the sensor unit 32 is shown in the summation point in Figure 5. The reducing agent supply system includes a dosing pump 24, a reducing agent conduit 25, a reducing agent tank 26, and an electronically controlled valve 27. The size of the reducing agent flow to be introduced may be adjusted by the input control algorithm shown in Figure 5. Figure 5 shows a closed-loop control system. The comparison results are sent to the input control algorithm. This input control algorithm supplies a signal to the dosing pump 24 to adjust the flow rate of the reducing agent introduced into the exhaust gas flow. Therefore, the flow rate of the reducing agent introduced into the exhaust gas flow is NO x It is controlled in a closed-loop manner to ensure that the reduction rate is equal to or greater than the required level. In situations where the reducing agent exceeds the limit (maximum supply limit), the control unit 50 may also be configured to provide input to the engine's performance control unit. In response to that input, the performance control unit controls the NO generated in the cylinder. x The cylinder process is modified to change the amount, and a new reduction rate setpoint is requested.
[0062] Valve systems 36 and 37 are located upstream of the SCR reactor 28 and NO (as shown in Figures 3 and 4). x The system may include a first control valve 36 provided in the flow path between the sensor unit 32 and the inlet, and a second control valve 37 provided in the pipeline communicating downstream of the SCR reactor 28. Alternatively, (not shown) the valve system may include a first port connected to an upstream position of the SCR reactor 28, a second port connected to a downstream position of the SCR reactor 28, and NO x It may have a 3 / 2-way valve with a third port connected to the inlet of the sensor unit 32.
[0063] NO downstream of valve systems 36 and 37 xA conditioning unit 29 may be placed upstream of the sensor device 32. The conditioning unit 29 is NO x The exhaust gas supplied to the inlet of the sensor unit 32 is heated (preferably to a temperature of 500-900°C), and / or NO x Adjust the pressure of the exhaust gas supplied to the sensor unit 32, and / or NO x The sensor unit 32 is configured to adjust the flow rate of exhaust gas to the inlet. The conditioning unit 29 may also include a filter or combination of filters for removing particles. The conditioning unit 29 may have a plurality of gas inlets and at least one gas outlet, as well as a pressure control unit.
[0064] The valve systems 36 and 37 may be incorporated into the conditioning unit 29.
[0065] NO x Sensor elements 33 and 34 may require periodic recalibration to maintain accuracy. Therefore, NO x The inlet of sensor unit 32 is NO x The sensor unit 32 is connected to a zero gas source for calibration. x The sensor unit 32 is connected to the inlet, and the reduction ratio of the SCR reactor is determined. Scavenging can be used as the zero gas. Alternatively, a pure CO2 source can be used as the zero gas. If it is desired to avoid exhaust gas entering the SCR reactor 28, the zero gas can also be sealing air (sealing gas) used when the SCR reactor 28 is not operating. Sealing air can be used when the SCR reactor 28 is not operating. This allows for zeroing through both the SCR inlet and outlet piping connections, thereby testing the conditioning unit 29 as well.
[0066] NO x The sensor unit 32 may also have a self-diagnostic function to check the health of the sensor. If the sensor detects NO outside the expected range... xIf a level is detected or a sensor malfunctions, the self-diagnostic function can trigger an error code in the engine's diagnostic system and warn a human operator of the problem.
[0067] The electronic control unit 50 is connected to the exhaust system upstream of the SCR reactor 28 when NO x The output of the sensor unit 32 is connected to the exhaust system downstream of the SCR reactor 28, and NO x As a function of the output of sensor unit 32, the NO of SCR reactor 28 x It is configured to calculate the return rate.
[0068] NO upstream of SCR reactor 28 x Concentration and downstream NO x By measuring the concentration with the same sensor unit, the reduction rate of the SCR reactor can be determined. x Because gain errors are eliminated when dividing by concentration, the gain error of the sensor unit is eliminated. Furthermore, measurements become less susceptible to noise. In addition, measurements become more stable even at low reduction rates.
[0069] Various aspects and implementation forms of the invention have been described with several embodiments. However, by examining the specification, drawings, and claims of this application, a person skilled in the art will understand and be able to implement many variations of the invention described in the claims in addition to the embodiments described. The words “equipment,” “having,” and “including” in the claims do not exclude the existence of elements or steps that are not described. Even if the number of elements described in the claims is not explicitly stated to be multiple, this does not exclude the existence of multiple such elements. The functions of some elements described in the claims may be performed by a single processor or electronic control unit. Even if several matters are described in separate dependent claims, this does not exclude the possibility of implementing them in combination, and such combinations may be beneficial.
[0070] The reference numerals used in the claims should not be construed as limiting the scope of the invention. Unless otherwise noted, the drawings are intended to be read together with the specification and constitute an integral part of the disclosure herein.
Claims
1. A large two-stroke uniflow scavenging turbocharged internal combustion engine, NO during engine operation ｘ Multiple cylinders that generate an exhaust gas flow including, A turbocharging system comprising an exhaust gas drive turbine located in the exhaust system and a compressor located in the scavenging system that supplies scavenging air to the cylinder, The exhaust system includes an SCR reactor, NO in the SCR reactor ｘ To cause this reaction, a reducing agent supply system is configured to add the input reducing agent flow to the exhaust gas, NO ｘ Sensor unit and Equipped with, The aforementioned NO ｘ The sensor unit detects NO in the gas supplied to its inlet. ｘ It is configured to generate an output corresponding to the concentration, The aforementioned organization is the NO ｘ The sensor unit is equipped with a valve system configured to selectively supply exhaust gas originating from either the upstream position of the SCR reactor or the downstream position of the SCR reactor at its inlet, An organization characterized by the following:
2. The aforementioned NO ｘ An electronic control unit is connected to the output of the sensor unit, and the electronic control unit controls the NO ｘ The engine according to claim 1, configured to adjust the magnitude of the input reducing agent flow supplied to the SCR reactor by the reducing agent supply system as a function of the output of the sensor unit.
3. The electronic control unit alternately supplies exhaust gas obtained from a position upstream of the SCR reactor and exhaust gas obtained from a position downstream of the SCR reactor to an inlet of the ｘ engine according to claim 2, which is configured to control the valve system.
4. The electronic control unit records the NO when exhaust gas originating downstream of the SCR reactor is supplied to the sensor. ｘ The output of the sensor unit is recorded by the electronic control unit when exhaust gas originating from upstream of the SCR reactor is supplied to the sensor, and the NO ｘ By dividing by the output of the sensor unit, the NO of the SCR reactor is obtained. ｘ The apparatus according to claim 3, configured to calculate the reduction rate.
5. The aforementioned electronic control unit calculates NO ｘ The engine according to claim 4, wherein a comparison is performed to compare the reduction rate with a reduction rate set value, and the magnitude of the input reducing agent flow supplied to the SCR reactor by the reducing agent supply system is adjusted as a function of the result of the comparison.
6. The valve system is - The upstream position of the SCR reactor and the NO ｘ A first control valve is provided in the flow path between the inlet and the sensor unit, - A second control valve is provided in a pipeline communicating downstream of the SCR reactor, or the first port is connected to the upstream position of the SCR reactor, the second port is connected to the downstream position of the SCR reactor, and the third port is the NO ｘ A 3 / 2-way valve connected to the inlet of the sensor unit, The apparatus according to claim 1, comprising:
7. The aforementioned NO ｘ The exhaust gas supplied to the inlet of the sensor unit is heated, and / or the NO ｘ Adjust the pressure of the exhaust gas supplied to the sensor unit, and / or the NO ｘ The engine according to claim 1, comprising a conditioning unit configured to adjust the flow rate of exhaust gas to the inlet of a sensor unit.
8. The engine according to claim 7, wherein the valve system is part of the conditioning unit.
9. The aforementioned NO ｘ The sensor unit has one or more NOs ｘ The engine according to claim 1, comprising a sensor.
10. The aforementioned NO ｘ The sensor unit contains one or more NOs ｘ The engine according to claim 1, further comprising an output processing unit configured to process the output from a sensor.
11. The aforementioned NO ｘ The entrance to the sensor unit is the NO. ｘ The engine according to claim 1, which is selectively connected to a zero gas source for calibrating a sensor unit.
12. A method for operating a large two-stroke uniflow scavenging turbocharged internal combustion engine, NO from multiple cylinders during the operation of the aforementioned engine ｘ To generate an exhaust gas flow that includes; A turbocharging system comprising an exhaust drive turbine for the exhaust system and a compressor for the scavenging system is used to supply scavenging air to the cylinder; NO in the SCR reactor of the exhaust system ｘ To cause this reaction, the reduced agent is added to the exhaust gas; NO ｘ NO in exhaust gas supplied to the sensor unit's inlet ｘ To generate an output corresponding to the concentration; The aforementioned NO ｘ The inlet of the sensor unit is selectively supplied with exhaust gas originating from either the upstream position of the SCR reactor or the downstream position of the SCR reactor; Methods that include...
13. The aforementioned NO ｘ The method according to claim 12, further comprising adjusting the magnitude of the input reducing agent flow supplied to the SCR reactor as a function of the output of the sensor unit.
14. The exhaust gas obtained from the upstream position of the SCR reactor and the exhaust gas obtained from the downstream position of the SCR reactor are used to obtain NO ｘ The method according to claim 13, comprising controlling the valve system to alternately supply to the inlet of the sensor unit.
15. When exhaust gas originating downstream of the SCR reactor is supplied to the sensor, the NO ｘ The output of the sensor unit is the NO when exhaust gas originating from upstream of the SCR reactor is supplied to the sensor. ｘ By dividing by the output of the sensor unit, the NO of the SCR reactor is obtained. ｘ The method according to claim 14, comprising calculating the reduction rate.
16. The above calculated NO ｘ The comparison involves comparing the return rate with the set return rate value; As a function of the results of the above comparison, the magnitude of the input reducing agent flow supplied to the SCR reactor is adjusted; The method according to claim 15, including the method described in claim 15.
17. The operating conditions of the cylinder are changed, and NO generated in the cylinder ｘ The method according to claim 16, further comprising increasing or decreasing.
18. The aforementioned NO ｘ Heating the exhaust gas supplied to the inlet of the sensor unit to a temperature between 500°C and 900°C, and / or the NO ｘ Adjusting the pressure of the exhaust gas supplied to the sensor unit, and / or The aforementioned NO ｘ Adjusting the flow rate of exhaust gas to the inlet of the sensor unit. The method according to claim 12, including the method described in claim 12.
19. The aforementioned NO ｘ One or more NOs within the sensor unit ｘ The method according to claim 12, further comprising processing the output from the sensor.
20. The aforementioned NO ｘ The inlet of the sensor unit is the NO. ｘ The method according to claim 12, further comprising selectively connecting the sensor unit to a zero gas source for calibration.