Exhaust gas recirculation device for four-stroke compression ignition engines.

Abstract

An exhaust gas recirculation (EGR) arrangement (100) for a single or multiple cylinder four-stroke compression ignition engine, the EGR arrangement (100) comprising an exhaust gas conduit in fluid communication between an EGR valve (51) and an EGR outlet (42), the EGR scrubber (70) being a water scrubber comprising a chamber (76) having a chamber inlet (71) and a chamber outlet (72), the chamber outlet (72) being positioned downstream of and in fluid communication with the chamber inlet (71). The exhaust gas conduit includes at least one water spray device (60) having at least one nozzle (64), the at least one water spray device (60) being arranged downstream of the EGR valve (51) and upstream of the chamber outlet (72), the water spray device (60) being connectable to a pressurized water source and configured to inject pressurized water into the exhaust gas conduit through the at least one nozzle (64) to increase the liquid surface area of ​​the injected water that contacts the exhaust gas in the exhaust gas conduit.

Description

[Technical Field]

[0001] The present disclosure relates to the field of exhaust gas recirculation (EGR) for compression ignition engines fueled with heavy and intermediate fuel oils or diesel (HFO / IFO / diesel), for stationary land-based uses such as in backup power generators, and for marine applications for marine propulsion and / or on-board power generation. [Background technology]

[0002] Nitrogen oxides, in the form of nitric oxide (NO) and nitrogen dioxide (NO), commonly referred to as NOx gases, are typically produced from the reaction of nitrogen and oxygen during the combustion of fuels, particularly at high combustion temperatures such as those present in compression-ignition combustion engines, also commonly referred to as diesel engines. NOx gases are harmful to the environment, contributing to the formation of smog and acid rain and also affecting tropospheric ozone. Therefore, engine manufacturers and manufacturers of engine exhaust gas cleaning equipment have developed solutions for cleaning engine exhaust gases by removing and reducing NOx gases from the engine exhaust gas stream.

[0003] Exhaust gas recirculation (EGR) works by recirculating a portion of an engine's exhaust gases back into the engine cylinders. This is typically accomplished by diverting the exhaust gases from the exhaust manifold and injecting the diverted gases into the engine's intake manifold. The EGR gases dilute the oxygen (O2) in the incoming airstream, providing a low-oxygen content gas to the engine intake for combustion in the cylinders. The addition of low-oxygen content EGR gases helps lower combustion temperatures; higher combustion temperatures result in more NOx being produced, and lower combustion temperatures result in less NOx emissions.

[0004] Another solution to reducing NOx formation in compression-ignition engines is to adjust fuel injection timing in relation to the piston's position relative to top dead center (TDC). Such adjustments can be made by delaying or retarding injection until a specific time after the piston reaches TDC. Alternatively, an additional injection of fuel can occur after the main injection. This reduces combustion temperatures, but results in undesirably increased fuel consumption. Thus, adjusting fuel injection can reduce NOx production. The challenge with adjusting fuel injection is that it increases overall fuel consumption, which in turn leads to increased production of environmentally harmful combustion products, including CO2 and NOx. Therefore, this solution is not a viable option for achieving or exceeding the stringent International Maritime Organization (IMO) Tier II and its equivalent for land-based installations.

[0005] Another solution to reducing NOx emissions is to implement a selective catalytic reduction device (SCR) in the engine's exhaust pipe. SCR works by converting NOx to nitrogen (N2) and water (H2O) with the aid of a catalyst. A reducing agent, typically ammonia (NH3), ammonium hydroxide (NH4OH), or urea (CO(NH2)2) solution, is added to the flue exhaust stream or exhaust gases and reacted over the catalyst. As the reaction proceeds to completion, nitrogen (N2) and carbon dioxide (CO2) are produced, in the case of urea.

[0006] SCR technology has been widely implemented in the automotive industry to reduce NOx emissions. For large engines, such as marine engines, the size required for SCR installations is large, resulting in high installation and SCR unit costs. Additionally, the cost of reductant required for continuous operation of an engine equipped with SCR technology adds to the overall engine operating costs. The need to install and / or maintain additional devices for the reductant, such as tanks, pumps, compressors, and similar devices, further increases system and operating costs. Finally, SCR technology that relies on reductant suffers from reductant slip, also known as ammonia slip, when reductant passes through the SCR unreacted. Reductant slip is undesirable and has a negative impact on the environment.

[0007] Increasingly stringent marine and land-based exhaust gas emission requirements for compression ignition engines from governmental and intergovernmental organizations, such as the International Maritime Organization (IMO), as well as requirements for land-based engine installations, have necessitated the development and implementation of new technological solutions to reduce NOx in gases emitted from compression ignition combustion engines.

[0008] Thus, it would be desirable to provide a solution for medium and high speed compression ignition engines for marine applications and land-based engine installations that improves the reduction of harmful NOx exhaust emissions, is cost effective to manufacture and install in new engine installations, and can be retrofitted onto current engine installations. Summary of the Invention

[0009] The present invention at least partially solves the above-mentioned problems by providing an exhaust gas recirculation (EGR) arrangement for a single or multiple cylinder, four-stroke, compression-ignition combustion engine, the EGR arrangement comprising: an exhaust gas conduit having an EGR inlet and an EGR outlet, the EGR inlet comprising an engine exhaust manifold for receiving a portion of combustion gases from at least one cylinder of the cylinder bank, the EGR outlet being arranged to be connected to an engine intake located upstream of a turbocharger compressor inlet; at least one controllable EGR valve arranged in fluid communication between the EGR inlet and the EGR outlet; and an EGR scrubber arranged in the exhaust gas conduit in fluid communication between the EGR valve and the EGR outlet. Thus, the EGR scrubber comprises: an EGR scrubber that is a water scrubber comprising a chamber having a chamber inlet and a chamber outlet, the chamber outlet being disposed downstream of and in fluid communication with the chamber inlet; and at least one water spray device comprising at least one nozzle, the at least one water spray device being disposed downstream of the EGR valve and upstream of the chamber outlet, the water spray device being connectable to a pressurized water supply source and configured to inject pressurized water into the exhaust gas conduit through the at least one nozzle to increase a liquid surface area of ​​the injected water that contacts the exhaust gas in the exhaust gas conduit.

[0010] The EGR arrangement is adapted for use with a compression ignition (CI) engine, also known as a compression-ignition combustion engine. The engine may have a linear or in-line configuration of engine cylinders. In the case of a linear or in-line configuration, the cylinders are aligned adjacent to one another to form a straight line. In this case, the engine cylinders may form a common cylinder bank. Alternatively, the engine cylinders may be arranged in a V-configuration, forming what is commonly referred to as a V-engine. In the case of a V-engine, the engine cylinders are divided into two separate cylinder banks, each disposed at an angle, such as 90 degrees, relative to the other cylinder bank. The EGR arrangement may also be used with engines with less conventional configurations. The EGR arrangement of the present invention may be arranged to circulate exhaust gases from a single cylinder, a cylinder bank having multiple cylinders, or multiple cylinder banks, such as the V-engine described above.

[0011] Each cylinder bank may be connected to an exhaust manifold at the engine exhaust. The exhaust manifold typically includes an exhaust gas inlet adapted to connect to the exhaust ports of the cylinder bank. The exhaust manifold further includes an exhaust outlet for connection to an exhaust system. The exhaust system may then include additional devices, such as an exhaust silencer or an exhaust gas aftertreatment device, and piping for connecting such devices together. At the end of the exhaust system, the exhaust gases are discharged to the ambient air through an exhaust system outlet, an exhaust pipe, or a chimney. The exhaust manifold combines the individual exhaust streams from the exhaust ports of the engine cylinders of the cylinder bank into a common exhaust stream that flows from the exhaust manifold outlet to the exhaust system. In this way, the technical advantage of the exhaust manifold is that it collects and combines multiple exhaust gas streams into one common exhaust gas stream. The exhaust manifold outlet may then be connected, either directly or through piping, to the exhaust turbine inlet of a turbocharger.

[0012] Further, the exhaust manifold may be connected to the exhaust ports of the cylinders through engine cylinder exhaust runners. The engine cylinder exhaust runners may be arranged in the form of pipe sections including a mounting flange attached at one end to the engine cylinder head, where the pipe sections transport exhaust gases from the individual engine cylinders to the body of the exhaust manifold. At the opposite end of the mounting flange, the exhaust runners may be welded or bonded to the body of the exhaust manifold through a further mounting flange. An exemplary exhaust manifold arrangement may be referred to as an exhaust manifold with individual exhaust runners.

[0013] An exhaust manifold is a solid cast iron structure that spans all cylinders in a cylinder bank, and may not have individual exhaust runners. For such an exhaust manifold, the exhaust manifold includes a body having exhaust gas inlet openings at one end corresponding to the number of exhaust ports in the cylinder bank. The manifold has a machine face adapted for mounting to an engine's cylinder head, with the inlet ports corresponding to those of the engine's cylinder head exhaust ports. The body also includes exhaust gas outlet openings. The inlet opening side is positioned to connect to the engine exhaust system through a mounting flange, and the outlet side is positioned to connect to the engine exhaust system using a flange or similar connection.

[0014] An exhaust manifold may also be in the form of an exhaust header, or simply a header. The header carries exhaust runners for the individual exhaust ports, often in the form of pipes or tubes with flanges for attachment to the individual exhaust ports of the cylinder bank. The individual exhaust runners merge into a common exhaust pipe or tube at a point or location called the collector, where the exhaust gases from the individual exhaust ports of the cylinder bank are combined into one common exhaust stream. The exhaust manifold may also form an integral part of the cylinder bank.

[0015] The function of the EGR conduit is to transport exhaust gases from the inlet of the EGR assembly to the outlet of the EGR assembly. The EGR conduit may be formed by multiple exhaust pipe sections bolted together through flanges, or the sections may be welded or bolted together. The sections may include: a first pipe section with an EGR inlet and connecting the EGR inlet to a controllable EGR valve; a second pipe section connecting the controllable EGR valve to an EGR scrubber; and a third section connecting the EGR scrubber to the engine intake through an EGR outlet. The EGR outlet is positioned to connect to the engine intake, preferably at a location upstream of the turbocompressor. This location may also be referred to as the low-pressure region of the turbocompressor. This allows EGR gas recirculation within the EGR conduit without the need for an EGR pump, thereby reducing the overall cost of the EGR assembly.

[0016] As described above, the EGR inlet is arranged to be connected to the engine exhaust manifold of the engine cylinder bank to receive a portion of the combustion gases from at least one cylinder of the cylinder bank. The EGR arrangement is adapted to receive exhaust gases from a relatively low-pressure region within the engine's exhaust manifold, which has the effect of cleaner gases and lower temperature and pressure compared to diverting exhaust gases from a relatively polluted, high-temperature / high-pressure region of the exhaust manifold. When exhaust gases from all cylinders of a cylinder bank are collected or merged into a common exhaust gas stream, the pressure and temperature of the exhaust gases increase. Furthermore, the levels of exhaust particles and unburned fuel also increase. By diverting exhaust gases upstream of the point where exhaust gases from all cylinders are collected into the common exhaust gas stream, the EGR arrangement provides exhaust gases with lower temperature, pressure, and levels of exhaust particles and unburned fuel compared to conventional solutions, i.e., after the collection point, i.e., downstream of the collection point. For example, the EGR inlet may be connected to the exhaust manifold at a longitudinal end of the manifold opposite the exhaust manifold outlet. The amount of burned gases received through the EGR inlet may be in the range of 5-10% of the total amount of exhaust gases from all cylinders in the cylinder bank. The amount of burned gases received through the inlet may be controlled by controlling the opening of the EGR valve.

[0017] When the exhaust manifold has individual exhaust runners, the exhaust gases can be diverted from a location within the individual exhaust runners by locating the EGR inlet within the individual exhaust runners, thereby allowing a portion of the exhaust gases to be diverted from a single cylinder to the EGR inlet.

[0018] At least one EGR valve is disposed in fluid communication between the EGR inlet and the EGR outlet. The EGR valve may be an electrically controllable EGR valve. The EGR valve controls the amount of exhaust gas flowing from the EGR inlet to the EGR outlet. The EGR valve may be controllable by a control unit to allow the exhaust gas flow to be increased or decreased depending on the engine load. Engine load or engine load factor is defined as the actual power output of an engine relative to its Maximum Continuous Rating (MCR). The load factor is usually specified as a percentage. For example, an engine running at 50% of its maximum load has a current load factor equal to 50%. The engine load signal is received and read from an engine control unit (ECU) and indicates the current engine load at which the engine is operating.

[0019] The EGR valve may be controlled to a closed position to deactivate the EGR component, and is located downstream of the EGR inlet and upstream of the EGR scrubber and / or water spray device.

[0020] The control unit may include a microprocessor, microcontroller, programmable digital signal processor, or other programmable device. The control unit may additionally or alternatively include an application specific integrated circuit, a programmable gate array or programmable array logic, a programmable logic device, or a digital signal processor. When the control unit comprises a programmable device such as a microprocessor, microcontroller, or programmable digital signal processor, the processor may further include computer executable code for controlling the operation of the programmable device.

[0021] Additionally, the at least one EGR valve may be set to a predetermined degree of opening when the EGR system is connected to an engine operating continuously and at a predetermined or preset engine load, such as in an onshore installation for a backup power generator, where the engine is operated at a predetermined load.

[0022] The configuration can further include a second controllable EGR valve located downstream of the EGR scrubber and upstream of the EGR outlet. This allows the EGR component to be isolated or disconnected from the engine by closing both EGR valves. This allows the engine to continue operating, even with increased NOx emissions, and allows the EGR scrubber or components of the EGR component to be repaired, cleaned, or serviced. Furthermore, if the first EGR valve mechanically fails and becomes stuck partially or fully open, the second EGR valve can be envisioned to throttle or control the amount of gas flowing from the EGR component to the EGR outlet, thereby controlling the amount of EGR gas flowing through the EGR component. The second EGR valve is preferably located after the exhaust gas has been cleaned, thereby reducing the risk of dirt or soot deposits on the second EGR valve. This also minimizes the risk of the second EGR valve malfunctioning.

[0023] By spraying or injecting pressurized water into the exhaust stream from a nozzle, the water breaks up into droplets or liquid droplets, forming a spray pattern and improving the surface area of ​​the water that contacts the exhaust gas stream. Increasing the liquid surface area of ​​the water injected into the exhaust stream improves exhaust gas scrubbing effectiveness by increasing the contact area between the water and the exhaust gas. The nozzle receives water from the water spray device and breaks the water into liquid droplets. Water droplets of a first size and volume may be divided into multiple smaller-sized droplets, which together have the same volume of water as the water droplets of the first size and volume. Thus, the total surface area of ​​the multiple water droplets is greater than the surface area of ​​the water droplets of the first size and volume. For any given volume of sprayed fluid, the exposed surface area is inversely proportional to the size of the droplets. Thus, halving the radius of the droplets doubles the surface area of ​​the fluid.

[0024] At least one water spray device may be disposed inside the EGR scrubber. At least one water spray device may be disposed to spray water into the EGR scrubber chamber. At least one water spray device may also be disposed upstream of the EGR scrubber and downstream of the EGR valve to spray water into the exhaust gas conduit. The EGR arrangement may include a combination of at least one water spray device disposed upstream of the EGR scrubber and at least one water spray device disposed to spray water inside the chamber. The water spray device may include a single spray nozzle disposed inside the EGR conduit, or a nozzle may be disposed inside the EGR scrubber chamber. The EGR arrangement may include more than one water spray device, such as, but not limited to, two or three water spray devices.

[0025] The EGR arrangement can include at least one water spray device disposed upstream of the EGR scrubber chamber and at least one water spray device disposed inside the EGR scrubber chamber. By locating one or more water spray devices upstream of the chamber, the size of the EGR chamber can be reduced, allowing for a reduction in the installation space required for the EGR chamber. This provides increased flexibility in installing the EGR arrangement on different types of engine installations and different types of engines.

[0026] The water spray device may also be pre-attached to a pipe section with a pre-welded or pre-fabricated mounting flange for connection to the pipe section of the EGR conduit. This allows for simple installation of the water spray device and pipe section into the EGR conduit because no on-site drilling or cutting is required to attach the water spray device itself to the pipe section. Both the water spray device and the EGR scrubber can be manufactured with pre-fabricated modular mounting flanges to reduce the time required to install the EGR components.

[0027] The water spray device may include multiple nozzles. Each nozzle may include at least one opening for spraying or injecting water into the exhaust gas stream. The nozzle openings may project water in multiple directions. The multiple directions may form a water spray pattern, such as a conical pattern. The nozzle openings may be sized to provide atomized water that mixes with the exhaust gas stream. Using the nozzles to spray or inject water increases the liquid surface area of ​​the water that contacts the exhaust gas in the exhaust gas conduit. This improves exhaust gas cooling and improves the capture and cleaning of combustion particles, such as soot. When the exhaust gas contacts the injected water, the water forms a mixture of exhaust gas and water vapor. When the water vapor condenses, the water vapor returns to liquid water in the form of droplets. In this way, the water droplets form and grow in size. During this process, combustion particles attach to the water droplets, and the droplets grow in size and collect at the bottom of the EGR chamber, where they are transported into a wastewater collection tank.

[0028] The water spray nozzle may be positioned at an opening in the wall of the EGR scrubber chamber or EGR conduit, with the water spray directed perpendicular to the exhaust gas flow. Multiple nozzles may be positioned around the circumference or inner surface of the EGR conduit. For example, if the EGR conduit includes a pipe section connecting the EGR valve to the EGR scrubber, multiple nozzles may be positioned to slightly protrude into the inner volume of the EGR conduit pipe, with the nozzles spaced apart around the circumference of the pipe. The water nozzle may also be pre-mounted on the pipe section with a mounting flange that simplifies field installation of the EGR assembly.

[0029] The water spray nozzles can be positioned to inject or spray water against and / or along the exhaust gas flow. For example, one nozzle may be positioned to spray against the exhaust gas flow and another nozzle may be positioned to spray along the exhaust gas flow. When the EGR conduit is made of a pipe section, the direction of the exhaust gas flow may be configured along the EGR conduit, for example along the central axis of the pipe. The nozzles may be positioned in a central location away from the wall of the chamber or EGR conduit. This may be achieved by positioning the nozzles on a pipe section that protrudes from the wall of the EGR conduit or chamber in a centrally located location within the pipe section or chamber.

[0030] The water spray device can be supplied with pressurized water from a pressurized water source at a pressure of 2 to 20 bar (0.2 to 2 MPa), preferably 4 to 10 bar (0.4 to 1 MPa), or even higher. The water pressure can be according to the nozzle manufacturer's specifications. The pressurized water source can be provided by a water pump or hydrophore tank, or similar pressurized water source.

[0031] At least one water spray device can include a controllable water valve for controlling the pressure and / or flow rate of water supplied to the nozzle. This allows multiple different water sources with different pressures and flow rates to be connected to the water spray device. The pressure and flow rate can also be adapted to the nozzle's specifications. For example, if the pressurized water source supplies water at a pressure of 10 bar (1 MPa) and the nozzle is specified by the nozzle manufacturer to operate optimally between 6 and 8 bar (0.6 and 0.8 MPa), the valve can be adjusted to accommodate the nozzle's operating range of 6 to 8 bar (0.6 to 0.8 MPa). Furthermore, the controllable water valve can be adjusted based on the flow rate of EGR gases entering the scrubber chamber. This is advantageous in that it reduces system water usage. The controllable valve can also be operated to close when the engine is turned off, thereby stopping water injection.

[0032] Each water spray device may have an individual controllable water valve, or they may share a common controllable water valve. When an EGR arrangement has multiple water spray devices, each with an individual controllable water valve, the water spray devices can be activated to spray water depending on engine load. Furthermore, activation of individual water spray devices can be based on the humidity of exhaust gases exiting the EGR scrubber. When the humidity is below a threshold, additional water spray devices can be activated by opening the respective controllable water valve. When the humidity is above a threshold, the amount of water injected can be reduced by operating the controllable water valve.

[0033] Furthermore, when an EGR component includes multiple water spray devices, each water spray device can operate at a different pressure and / or flow rate. This can reduce the amount of water required to operate the EGR component. Furthermore, this allows a first water spray device to provide the majority of the water spray to the exhaust gas flow, while a second water spray device can be used to fine-tune and optimize the water spray flow and pattern for the exhaust gas cleaning process. Additionally, the first controllable water valve may be selected to have a lower control resolution for controlling the pressure and / or flow rate. For example, the first valve may be controllable to set the opening degree in 10% increments, while the second valve may be controllable to set the opening degree in 1-5% increments.

[0034] The EGR scrubber is located downstream of the EGR valve and upstream of the EGR outlet. The EGR scrubber includes a chamber having an exhaust gas inlet and an exhaust gas outlet. The chamber may have a cylindrical shape, a box shape, or any other shape useful for optimizing flow through the chamber. The chamber may also have a shape that fits the space constraints for engine installation. For example, a cylindrical shape that tapers or widens between the chamber inlet and outlet. The chamber may be manufactured from multiple sections, allowing for easy disassembly and maintenance. For example, the chamber may be manufactured in two halves that can then be welded or bolted together.

[0035] The chamber inlet is positioned to receive exhaust gas flowing from the EGR valve toward the EGR scrubber. The chamber outlet is positioned upstream of and fluidly connected to the EGR outlet. The chamber may also be interpreted as having an inlet portion, an intermediate portion, and an outlet portion. The inlet portion may have a conical shape that widens from the diameter of the chamber inlet opening to the diameter of the intermediate portion. Furthermore, the outlet portion may have a conical shape that tapers toward the intermediate portion. The diameter of the chamber may be larger than the diameter of the inlet and / or outlet of the chamber. The widening of the inlet portion and the tapering of the outlet portion provide a connection interface for the EGR scrubber to use EGR conduit piping of the same diameter with intermediate chamber portions of different diameters or widths. In this way, EGR conduit piping of the same diameter can be used with EGR scrubbers of different diameters or widths. When the intermediate EGR chamber portion is box-shaped, the chamber inlet may have a widening truncated pyramidal or frustum shape, and the chamber outlet may have a tapered sub-pyramidal or frustum shape. The flared shape of the chamber inlet helps reduce the velocity of the exhaust gases entering the EGR scrubber. By slowing the exhaust gases inside the chamber, water vapor condensation inside the chamber is improved.

[0036] The EGR scrubber may further include a wastewater collection tank for collecting wastewater and at least one controllable wastewater valve in fluid communication with the wastewater outlet of the wastewater collection tank, the valve configured to control removal of collected wastewater containing combustion particles such as soot from the chamber by opening the at least one wastewater valve. The wastewater collection tank is connected to and in fluid communication with the EGR scrubber chamber through a plurality of longitudinally extending slits or openings in the bottom of the chamber. The slits or openings are preferably arranged parallel to and spaced apart from each other to allow water to flow from the chamber to the wastewater collection tank. The slits or openings are aligned with the central axis of the EGR chamber. When water sprayed into the exhaust gas flow by the nozzle of the water spray device condenses in the chamber, the wastewater collects at the bottom of the chamber by gravity. The water then flows into the wastewater collection tank through the slits or openings arranged in the bottom.

[0037] The chamber can include at least one or more perforated plates with a plurality of openings, the perforated plates being positioned inside the chamber downstream of the at least one water spray device, the perforated plates promoting and improving condensation of water vapor within the chamber as the water vapor contacts and is cooled by the perforated plates.

[0038] The plates may be made from a material that is resistant to corrosion by a mixture of water and steam containing combustion particles. The perforated plates may be made from stainless steel, titanium, or other materials that are resistant to corrosion. The plates may also be made from plastic or composite materials. The plates and chamber may be 3D printed, which allows the plates to be manufactured in place inside the chamber and eliminates the need to assemble the plates within the chamber, which is required when manufacturing the chamber and plates using standard manufacturing techniques, such as high-pressure water cutting. The plates may be made from metal or plastic with pressed or drilled openings.

[0039] Combustion particles, such as soot, are thereby removed from the exhaust gas flow, and the amount of combustion particles or soot at the EGR outlet is reduced compared to the EGR inlet. In this way, the exhaust gas is cleaned and cooled. The perforated plate can have an outer edge shape that matches the cross-sectional shape of the chamber. The plate can be square, rectangular, oval, or circular. Additionally, the perforated plate can have a convex shape.

[0040] The chamber may comprise a plurality of perforated plates arranged in a stacked configuration at a distance from each other, the distance between two plates being defined and measured along a normal to the surface of the perforated plate, the distance preferably being equal at all positions on the plate.

[0041] The arrangement can include a plurality of perforated plates, with first and second perforated plates disposed at an angle relative to each other, although the plates may be disposed at an angle relative to each other such that the distance between the two plates varies along the perforated plate surfaces of the two plates. Alternatively, several plates may be mounted in a stacked parallel orientation, with intermediate plates disposed at an angle relative to the stacked parallel plates.

[0042] The holes or openings in the perforated plate may be circular. Alternatively, the openings may be oval, square, or rectangular in shape. Other shapes, such as octagonal or hexagonal, are also possible. Circular or oval shapes may be advantageous in that they reduce the risk of crack formation and propagation at the boundary edges of the openings caused by thermal cycling. The exhaust gas mixed with the water vapor is guided by the perforated plate and directed through the openings in the perforated plate, slowing the mixture and cooling and condensing the water vapor in the mixture. As the water vapor condenses into droplets, the water is collected via gravity in a wastewater collection tank.

[0043] The openings in a first perforated plate may have a different shape and / or size than the openings in a second perforated plate in a stack of perforated plates. When a chamber comprises at least one first and second perforated plate, the diameter of the openings in the first perforated plate may be the same as or different from the diameter of the openings in the second perforated plate. When the openings are of different shapes, the width of the openings in the first perforated plate may be different from the width of the openings in the second perforated plate. The diameter or width of the openings in the first perforated plate may be larger than the diameter or width of the openings in the second perforated plate. The openings in the first perforated plate may thereby be adapted to accept exhaust gas entering the chamber at a higher exhaust flow rate.

[0044] The chamber can further include first and second perforated plates, where the openings in the first perforated plate are radially offset from the openings in the second perforated plate. By radially offsetting the openings, the distance that exhaust gas and water vapor must travel to pass through the first and second perforated plates is increased. By radially offsetting the openings in the first and second perforated plates, the openings in the first perforated plate do not line up with the openings in the second perforated plate.

[0045] Additionally, the size or dimensions of the first perforated plate, e.g., diameter, may be different from the size or dimensions of the second perforated plate, such as may be the case when the EGR scrubber chamber has a flared or tapered shape, and the diameter of the second perforated plate may be smaller or larger to match the shape of the chamber.

[0046] Also, as described above, the EGR arrangement may further include a control unit electrically connected to the EGR valve and configured to control the controllable EGR valve to a position to regulate the amount of exhaust gases recirculated from the EGR inlet to the EGR outlet based on an engine load signal. The control unit may include processing circuitry configured to control the controllable EGR valve to regulate the amount of exhaust gases recirculated from the EGR inlet to the EGR outlet based on the engine load signal. The control unit may include predefined models or maps for different opening amounts of the EGR valve depending on the engine load signal.

[0047] The EGR arrangement may further include at least one humidity sensor disposed downstream of the EGR chamber to determine the amount of water in the exhaust gas stream, the at least one humidity sensor being electrically connected to the control unit. The humidity sensor measures or determines the water vapor or humidity of the exhaust gas downstream of the EGR scrubber. One or more humidity sensors may be used to determine humidity at different locations downstream of the EGR scrubber. Two humidity sensors may be positioned to measure humidity at the same location in the EGR conduit. This provides fallback humidity sensor data in case one sensor fails, thereby increasing system uptime. Alternatively, two humidity sensors using different sensing technologies may be used, whereby an average value of the two sensors may be calculated or determined by the control unit.

[0048] The EGR arrangement may further include at least one oxygen sensor disposed in the exhaust gas conduit between the chamber or EGR scrubber and the EGR outlet, the oxygen sensor being configured to determine the amount of oxygen in the exhaust gas stream, the oxygen sensor being electrically connected to the control unit. One or more oxygen sensors may be disposed downstream of the EGR scrubber to detect the amount of oxygen, the one or more sensors being connected to the control unit. Data from the one or more oxygen sensors may be stored or analyzed to determine the efficiency of the EGR arrangement. The use of the oxygen sensors may improve the efficiency of the EGR arrangement. The one or more oxygen sensors may be optical oxygen sensors, such as differential optical absorption spectroscopy (DOAS) sensors. Alternatively, the one or more sensors may be state-of-the-art oxygen sensors suitable for measuring the amount of oxygen in the exhaust gas stream.

[0049] The oxygen sensor can be located within the scrubber chamber near the chamber outlet and downstream of the perforated plate, or it can be located outside the scrubber chamber in the EGR conduit located upstream of the EGR outlet.

[0050] The EGR arrangement further includes at least one temperature sensor disposed in the exhaust gas conduit between the chamber and the EGR outlet, the temperature sensor being electrically connected to the control unit. A temperature sensor may also be disposed outside the scrubber chamber at a location in the EGR conduit upstream of the EGR outlet. The EGR arrangement may include additional temperature sensors so that the temperature of the exhaust gas stream can be measured upstream of the scrubber. Data from the one or more temperature sensors may be transmitted to the control unit for analyzing the performance of the EGR arrangement.

[0051] The control unit may include processing circuitry adapted to execute program executable code, read data from the sensors, and send control signals to operate the controllable valves of the EGR component. The control unit may also be connected to transfer EGR component operation data to the engine management system. The control unit may also store data for later use, including analysis, also known as data logging.

[0052] The control unit can include processing circuitry configured to control a controllable water valve to control the pressure and / or flow of water provided to the water spray device based on data from sensor(s), including a humidity sensor, a temperature sensor, and an oxygen sensor. This allows adapting the amount of injected water based on the amount of exhaust gas flowing through the EGR conduit as a function of the engine load signal to optimize water usage. The control unit can also be configured to control the controllable water valve to control the pressure and / or amount of water provided to the water spray device based on data from the sensor(s) and / or based on the EGR valve position or the engine load signal.

[0053] The control unit may further be connected to the controllable waste water valve for controlling the waste water valve to assume a position that allows waste water to be removed from the chamber, thereby controlling the removal of waste water from the chamber and preventing the chamber from overfilling with waste water.

[0054] The chamber can include a low wastewater level sensor indicating a low wastewater level in the chamber and a high wastewater level sensor indicating a high wastewater level in the chamber, and the control unit is configured to control the controllable wastewater valve to an open position allowing removal of wastewater from the wastewater collection tank when the wastewater level is above the high wastewater level and to a closed position preventing removal of wastewater from the wastewater collection tank when the wastewater level is below the low wastewater level. When the wastewater level is below a minimum threshold wastewater level or a "low" level, the low wastewater level sensor sends a signal to the control unit or similar hardware such as a programmable logic controller (PLC). The control unit or sensor can also send a signal to the wastewater valve to close the valve. When the wastewater level is above a threshold indicating a high wastewater level, the high wastewater level sensor can also send a signal to the control unit or similar hardware such as a programmable logic controller (PLC). The control unit or sensor can also send a signal to the wastewater valve to open the valve and release wastewater from the wastewater collection tank. Maintaining the wastewater level within the low and high range reduces the risk of exhaust gases leaking through the EGR scrubber chamber and overpressure in auxiliary equipment connected to the wastewater valve. This also reduces the risk of exhaust gases leaking and harming onboard personnel. The use of low and high level sensors also reduces the duty cycle of the wastewater removal pump, reducing the pump's energy consumption and extending its lifespan.

[0055] The EGR arrangement may further include a critical wastewater level sensor that indicates a critical wastewater level, and the control unit may be configured to control at least one EGR valve to a closed position and at least one controllable water valve to a closed position to prevent injection of pressurized water into the exhaust gas conduit. The critical wastewater level sensor indicates that the wastewater level has risen above a high level, to a "high-high" level. This may indicate a problem with the wastewater valve, such as clogging or blockage. Furthermore, a level above the critical level may indicate a problem with the control unit's control of the wastewater valve. If the wastewater level exceeds a threshold indicating the wastewater level is critical, the critical wastewater level sensor may signal the control unit or similar hardware, such as a programmable logic controller (PLC). Furthermore, the sensor or control unit may generate an audible alarm signal in the engine control room. Furthermore, the control unit or critical level sensor may signal the EGR inlet valve(s) to close, isolating the EGR arrangement from the engine. Additionally, the controllable water valve of the water spray device may be operable to discontinue or stop the supply of pressurized water to the nozzle of the water spray device.

[0056] Additionally, wastewater removal may be commanded by a control unit that operates a wastewater valve to open after the engine is shut off to prevent wastewater from remaining in the wastewater collection tank for an extended period of time, or to allow wastewater to be removed during scrubber maintenance or cleaning.

[0057] At least one EGR scrubber may be disposed inside an outer housing, the outer housing having an inlet opening and an outlet opening. In this case, a cooling fluid from outside the outer housing is supplied to the housing using at least one of a fan, blower, or pump to cool the outer surface of the at least one EGR scrubber. The cooling fluid flows through the inlet opening and the outer housing and out the outlet opening. The cooling fluid may be a liquid such as air or water, including seawater. Placing the scrubber inside the housing can reduce noise inside the engine or machinery room. It also allows for vents to air-cool the outer surface of the scrubber, which in turn improves cooling of the exhaust gas flow and condensation inside the EGR scrubber. Cooling air may be supplied to the housing inlet from an air fan or air blower. After cooling the outer surface of the EGR scrubber, the now-heated air can flow out of the housing through the housing outlet. The housing inlet and outlet may be connected to a location outside the hull / facility through an air duct. This also allows heat from the engine room to be removed to a location outside the hull / facility, reducing heat soak within the engine room.

[0058] The EGR arrangement may further include at least a second EGR scrubber disposed in fluid communication between the first EGR scrubber and the EGR outlet. In this case, the second EGR scrubber may operate in series with the first EGR scrubber. This provides improved performance in larger engine sizes because exhaust gas scrubbing occurs in two steps: a first primary step using the first EGR scrubber and a secondary step using the second EGR scrubber. Furthermore, the EGR arrangement may include more than two EGR scrubbers arranged in series, and exhaust gas scrubbing may occur in multiple steps corresponding to the number of EGR scrubbers in the EGR arrangement.

[0059] Using multiple EGR scrubbers in series allows two small EGR scrubbers to be replaced with a single large EGR scrubber. This allows for greater flexibility when installing EGR components into current engine installations. Furthermore, two small EGR scrubbers may be less expensive than one large EGR scrubber. Furthermore, manufacturing only one standard size EGR scrubber may be less expensive than manufacturing EGR scrubbers in a wide range of sizes.

[0060] The EGR arrangement may also include a second or more EGR scrubbers positioned between the EGR inlet and the EGR outlet and operating in parallel with the first EGR scrubber.

[0061] When an EGR arrangement is installed in a V-type motor, each of the cylinder banks of the motor may have an individual EGR arrangement connected to it. Alternatively, only one of the cylinder banks may be connected to an EGR inlet for receiving exhaust gases, with the EGR outlet of the EGR arrangement positioned to supply cleaned exhaust gases to the intake sides of both cylinder banks, such as upstream of a shared turbocharger compressor inlet. If separate turbochargers are used for the cylinder banks, the EGR outlet may be split into two outlets, each connected to supply cleaned exhaust gases to a respective turbocharger compressor inlet.

[0062] When the EGR scrubbers operate in parallel, a controllable diverter valve is disposed downstream of the EGR valve and upstream of the first and second EGR scrubbers, and the diverter valve is controllable to divert a portion of the EGR gas flow from the exhaust gas flow in the exhaust gas conduit to the second EGR scrubber. This arrangement can divert all of the exhaust gas flow to either the first or second scrubber, or the exhaust gas flow can be split between the two EGR scrubbers. In this case, operation of the EGR arrangement can be performed using one or more EGR scrubbers depending on engine load. Additionally, this can optimize engine uptime or operating time, because exhaust gas entering the EGR conduit can be completely diverted to one of the EGR scrubbers, allowing for maintenance or repair of the EGR scrubber that does not receive exhaust gas. Additionally, for some engines operating at low loads, a subset of the cylinders can be deactivated by not injecting fuel into them to conserve fuel. This is also called cylinder deactivation. During cylinder deactivation, a diverter valve may divert all of the exhaust flow to a single EGR scrubber. When two or more EGR scrubbers operate in parallel, they may be merged into a common exhaust gas flow downstream of the EGR scrubber and upstream of the EGR outlet.

[0063] For cases where the EGR system includes multiple EGR scrubbers, the size of the second EGR scrubber may be different from the size of the first scrubber.

[0064] A second aspect of the invention relates to a four-stroke compression engine including an exhaust gas recirculation (EGR) arrangement according to any one of the above examples.

[0065] The engine may include at least one cylinder bank and an exhaust manifold attached to the cylinder bank, where the EGR inlet is connected to the exhaust manifold at a location upstream of an exhaust gas collection point, the collection point being a point within the exhaust manifold where exhaust gases from the engine cylinder banks join to form a common exhaust gas stream including exhaust gases from each cylinder of the engine cylinder bank.

[0066] An engine including the above EGR arrangement may be said to have an EGR inlet connected to each cylinder engine exhaust gas runner in the exhaust manifold.

[0067] An engine including an EGR arrangement may include an exhaust manifold having a plurality of manifold inlets connected to a corresponding number of engine exhaust ports and an exhaust manifold outlet connected to the engine exhaust system, wherein the EGR inlet is connected to the exhaust manifold upstream of the exhaust manifold outlet and downstream of the plurality of manifold inlets.

[0068] An engine including an EGR arrangement may be said to have an EGR outlet connected to the engine intake upstream of the turbocompressor.

[0069] An engine including an EGR arrangement may be equipped with a control unit that is capable of controlling the EGR valve to divert 5-10% of the combustion gases from the exhaust manifold to the EGR inlet.

[0070] Aspects and embodiments will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0071] [Figure 1]FIG. 1 illustrates a schematic diagram of an engine-mounted EGR arrangement according to an exemplary embodiment. [Figure 2] FIG. 2 illustrates an exhaust manifold with a connection to an EGR inlet of an EGR arrangement according to an exemplary embodiment. [Figure 3] FIG. 3 illustrates an EGR arrangement having two EGR scrubbers and a water spray device operating in series, according to an exemplary embodiment. [Figure 4] FIG. 4 illustrates an EGR arrangement having two EGR scrubbers and water spray devices operating in parallel, according to an exemplary embodiment. [Figure 5] FIG. 5 shows an enlarged view of the exemplary water spray device of FIG. [Figure 6] FIG. 6 shows a close-up view of an exemplary EGR scrubber including two water spray devices. [Figure 7] FIG. 7 shows an example of a perforated plate arrangement inside the EGR scrubber chamber. [Figure 8] FIG. 8 shows a wastewater collection tank with a wastewater valve and sensor arrangement. [Figure 9] FIG. 9 shows an example of a perforated plate. [Figure 10] FIG. 10 shows an example of an EGR arrangement located within an outer housing. DETAILED DESCRIPTION OF THE INVENTION

[0072] Aspects of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which specific embodiments of the invention are shown.

[0073] These aspects may, however, be embodied in many different forms and should not be construed as limiting. Rather, these aspects and embodiments are provided as examples so that this disclosure will be thorough and complete, and will fully convey the scope of all aspects of the present invention to those skilled in the art. Like numbers refer to like elements throughout the specification.

[0074] FIG. 1 illustrates an exemplary embodiment of an EGR arrangement 100 installed on an in-line, four-cylinder, compression-ignition engine 1. The engine 1 has a common cylinder bank 10 including four cylinders of the engine 1. A first cylinder 11, a second cylinder 12, a third cylinder 13, and a fourth cylinder 14 are shown in FIG. 1. The engine 1 has an intake side with an intake manifold 21 connected downstream of a turbocharger compressor 22. The engine 1 also has an exhaust side with an exhaust manifold 31 attached to the engine. The exhaust manifold 31 is disposed upstream of a turbocharger turbine 32. The exhaust manifold 31 has four exhaust gas inlets 33, each connected to an individual exhaust gas port of the first cylinder 11, the second cylinder 12, the third cylinder 13, and the fourth cylinder 14 of the engine 1. Additionally, the exhaust manifold 31 includes a common exhaust outlet 34 for connection to the engine exhaust system (not shown). The manifold 31 combines the exhaust gas streams from the individual exhaust ports into a common exhaust gas stream at the outlet 34, which is sometimes referred to as a collection point 34. The EGR arrangement includes an EGR inlet 41. The EGR arrangement is connected to a port or opening in the exhaust manifold 31. The EGR inlet 41 is positioned to receive exhaust gas from a low-pressure region of the exhaust manifold 31 when the engine 1 is operating. FIG. 1 shows the EGR inlet 41 positioned within the exhaust manifold 31 at a short end of the exhaust manifold 31 opposite the short end of the exhaust manifold outlet 34. This provides for exhaust gases with significantly lower pressure, temperature, and amounts of soot and unburned fuel entering the EGR inlet.

[0075] The EGR assembly 100 includes an EGR conduit beginning with an EGR inlet 41 for receiving exhaust gases from the exhaust manifold 31 of the engine 1, and an EGR outlet 42 for providing cleaned exhaust gases to the turbocharger compressor inlet 23.

[0076] The EGR arrangement 100 includes a pipe section 101 for connecting the EGR inlet 41 to a controllable EGR valve 51 located downstream of the EGR inlet 41. The pipe section 101 may include a cooling structure (not shown), e.g., an air or liquid cooling structure, to reduce the temperature level of the exhaust gases within the pipe section 101. The controllable EGR valve 51 is also shown located upstream of the EGR scrubber 70. The EGR valve 51 is controllable to adjust or control the amount of exhaust gases recirculated through the EGR arrangement and the EGR conduit. A further pipe section 102 connects the EGR valve 51 to the EGR scrubber 70.

[0077] The water spray device 60 is disposed between the EGR valve 51 and the EGR scrubber 70. The water spray device 60 is disposed upstream of the EGR scrubber 70 and downstream of the EGR valve 51. The water spray device 60 is further disclosed below in connection with the description of FIGS. 5-6. The water spray device 60 injects or sprays atomized water into the exhaust gas to cool the exhaust gas and to facilitate removal of exhaust gas combustion particles or soot from the exhaust gas. FIG. 1 shows the water spray device disposed in the widened pipe section 67 relative to the pipe section 102. The water spray device 60 further includes a controllable water valve 61 for controlling the flow rate and / or pressure of the water. The controllable water valve is further fluidly connected to a pressurized water supply (not shown).

[0078] The EGR scrubber 70 includes an inlet 71 and an outlet 72. The inlet 71 is located downstream of the water spray device 60 and the EGR valve 51. The outlet 72 is located downstream of the EGR scrubber inlet 71 and upstream of the EGR outlet 42. The EGR scrubber 70 is further shown to include a chamber 76 extending between the EGR inlet 71 and the EGR outlet 72. The chamber 76 is shown to include a plurality of perforated plates 73 for cooling and cleaning the exhaust gas by condensing water vapor containing suspended combustion particles. As the exhaust gas and water vapor mixture cools, the water vapor forms water droplets carrying combustion particles or soot. FIG. 1 also shows that the EGR scrubber 70 includes a wastewater collection tank 74 extending from the chamber 76 for collecting condensed water carrying combustion particles or soot. The water collected in the wastewater collection tank 74 is sometimes referred to as wastewater. The wastewater collection tank 74 further includes an opening 75 at the bottom of the tank 74 and a controllable wastewater valve 62 connected to the opening 75. The wastewater valve 62 can be electrically or manually controlled to an open position to allow wastewater to exit the wastewater collection tank 74 of the EGR scrubber 70.

[0079] Three sensors 81, 82, 83 are positioned downstream of the EGR scrubber outlet 72 to measure properties of the cleaned gas stream. Sensors 81, 82, 83 are shown as a humidity sensor 81 for sensing the amount of water and / or water vapor in the exhaust stream downstream of the EGR scrubber outlet 72, a temperature sensor 82 for sensing and determining the temperature of the cleaned exhaust gases, and an oxygen sensor 83 for determining the oxygen content of the cleaned exhaust gases.

[0080] 1 also shows an optional second EGR valve 52 located downstream of the above-disclosed sensors 81, 82, 83. The second EGR valve 52 is controllable to close and isolate the EGR arrangement 100 or to prevent the EGR arrangement 100 from delivering exhaust gases, for example, to deliver cleaned exhaust gases to the EGR outlet 42 upstream of the turbocharger compressor 22 and to the engine intake 23.

[0081] FIG. 1 further illustrates a control unit 200. The control unit 200 is electrically connected to the first EGR valve 51 and is also electrically connected to the second EGR valve 52. The control unit 200 includes a processing circuit adapted to run executable code configured to control the opening and closing of the EGR valves 51, 52. The control unit 200 is also electrically connected to the controllable water valve 61 of the water spray device 60. The control unit 200 can thereby control the opening and closing of the controllable water valve 61 to regulate the pressure and flow rate of the water spray toward the exhaust stream. The control unit 200 is also electrically connected to the controllable wastewater valve 62. In this manner, the control unit 200 can control the removal of wastewater from the wastewater collection tank 74 and prevent the EGR scrubber 70 from overfilling with wastewater. The control unit 200 is also connected to receive sensing data from the sensors 81, 82, and 83. This sensing data may be provided with executable code for controlling the injection of water into the exhaust gas stream, the removal of wastewater from the wastewater collection tank 74 of the EGR scrubber 70, and the opening of the first EGR valve 51 and the second EGR valve 52. In particular, the injection of water may be controlled in response to sensing data, for example, from the humidity sensor 81, to reduce the risk of water or condensation entering the engine intake manifold 21. The control unit 200 may also be connected to an engine control unit ECU2. The control unit may receive engine operating data, including an engine load signal, from ECU2 and input that data into a control program or executable code running on the control unit 200.

[0082] FIG. 2 illustrates an exemplary engine 1 according to FIG. 1 , including an alternative to the exhaust manifold of FIG. 1 . The exhaust manifold 31′ includes individual exhaust gas port runners 33′ connecting the exhaust ports 33′ of each of the cylinder banks 10 to the main body 37 of the exhaust manifold 31′. FIG. 2 shows that an EGR inlet 41′ is connected to the exhaust gas runner of the first cylinder 11 of the engine 1. Dashed line 39 in FIG. 2 schematically illustrates the exhaust gas flow in the exhaust manifold and shows how a portion of the exhaust gas from the exhaust gas runner of the first cylinder 11 is diverted and supplied to the EGR inlet 41′ of the EGR arrangement. The exhaust gas supplied to the EGR inlet 41 thereby contains primarily or entirely exhaust gas from the first cylinder 11. In this manner, the exhaust gas is diverted upstream of a collection point 34 of the exhaust gas manifold 31′, where exhaust gases from all cylinders join to form a common exhaust stream.

[0083] FIG. 3 shows a variation of the EGR arrangement 100 of FIG. 1. The EGR arrangement 100′ of FIG. 3 includes an additional second water spray device 60′ and an EGR scrubber 70′, which are located downstream of the first EGR scrubber 70 and upstream of the EGR outlet 42. The EGR scrubber arrangement 100′ shown in FIG. 3 operates in two cleaning stages, where the EGR gas is cleaned using two EGR scrubbers 70, 70′ operating in a series configuration. The second EGR scrubber 70′ is further shown to include a plurality of perforated plates 73′ and a wastewater valve 62′. Additionally, the EGR valve 52 is located downstream of the second EGR scrubber 70′. FIG. 3 also shows that the second water spray device 60′ includes a controllable water valve 61′. 3 shows a first humidity sensor 81 located downstream of the first EGR scrubber 70 and upstream of the second EGR scrubber 70', and a second humidity sensor 81' located downstream of the second EGR scrubber 70'. A temperature sensor and a humidity sensor are located downstream of the second EGR scrubber 70'.

[0084] FIG. 4 illustrates an alternative EGR arrangement 100″ according to an exemplary embodiment. The alternative EGR arrangement 100″ includes a first EGR scrubber 70 and a first water spray device 60 according to the EGR arrangement disclosed in connection with FIG. 1 . The EGR arrangement 100″ further includes a second EGR scrubber 70″ and a second water spray device 60″. The first scrubber 70 and the second scrubber 70″ are disposed downstream of the EGR valve 51 and the diverter valve 80. The diverter valve 80 is a controllable three-way valve electrically connected to the control unit 200 disclosed in connection with FIG. 1 . The three-way valve is controllable to control the amount of exhaust gas flowing into the first EGR scrubber 70 and the second EGR scrubber 70″. Furthermore, the second EGR scrubber 70″ of FIG. 4 is disclosed to be smaller in size compared to the first scrubber 70. The second EGR scrubber 70" has a diameter approximately half that of the first EGR scrubber 70. When the EGR arrangement 100" is operating on the engine at low engine loads, the diverter valve 80 is controllable to position either one of the two EGR scrubbers 70, 70" in a position where it is not supplied with exhaust gases. In this way, one of the EGR scrubbers 70, 70" is placed in a non-operating mode. When the EGR arrangement 100" is operating on the engine at high engine loads, the diverter valve 80 can position both EGR scrubbers 70, 70" in a position where they are supplied with exhaust gases. Downstream of the EGR scrubbers 70, 70" and upstream of the EGR valve 52 and EGR outlet 42, the two cleaned gas streams join at a junction 84 to form a common cleaned gas stream that is supplied to the turbocharger compressor inlet. FIG. 4 shows that the first EGR scrubber 70 and the second EGR scrubber 70'' each include a respective humidity sensor 81, temperature sensor 82, and oxygen sensor 83. Additionally, FIG. 4 shows that the second EGR scrubber includes a wastewater valve 62'.

[0085] FIG. 5 illustrates an enlarged view of the water spray device 60 shown in FIG. 1 , according to an exemplary embodiment. The water spray device 60 includes a controllable water valve 61. The controllable water valve 61 is connected to a pressurized water supply (not shown). The water spray device 60 further includes a pipe section 63 connecting the controllable water valve 61 to a first nozzle 64 and a second nozzle 65. Both nozzles 64, 65 are aligned with a central axis A of the exhaust conduit. The first nozzle 64 is positioned to face the exhaust gas flow. The second nozzle 65 is positioned facing in a direction opposite the first nozzle 64, along the exhaust gas flow. Each nozzle is shown to have multiple openings for spraying water into the exhaust gas flow through water jets that form a spray pattern 66. The pattern 66 formed by the first nozzle 64 and the second nozzle 65 is shown to have a cone-like shape. The water jets in the pattern 66 evaporate, forming a mixture of exhaust gas and water vapor. Downstream of the second spray nozzle 65 , the exhaust gas and water vapor mixture enters the EGR scrubber chamber inlet 71 .

[0086] FIG. 6 shows an enlarged view of an exemplary embodiment of an EGR scrubber 700, in which the first and second water spray devices 60 are disposed inside a chamber 76. The EGR scrubber 700 includes a chamber 76 having an inlet 71 and an outlet 72. A plurality of perforated plates 73 are disposed within the chamber 76, with the plates 73 disposed downstream of the inlet 71 and upstream of the outlet 72. The chamber 76 preferably has a cylindrical or box-like shape. The perforated plates 73 are shown disposed perpendicular to and extending from an inner wall or surface 77 of the chamber. FIG. 6 illustrates the chamber including perforated plates 73, with openings 78 in the perforated plates 73 radially offset from the openings 78 in adjacent perforated plates 73. This increases the distance the exhaust gases must travel through the chamber 76 to get from the inlet 71 to the outlet 72 and slows the exhaust gas velocity. This enhances the cooling effect provided by the perforated plates, thereby improving cleaning efficiency.

[0087] FIG. 6 shows the wastewater collection tank 74 of the EGR scrubber 70, positioned to collect wastewater 90. As the mixture of water vapor and exhaust gas enters the chamber and contacts the perforated plate 73, the mixture is cooled until the water vapor condenses into droplets containing water and suspended combustion particles, such as soot or unburned fuel. The water then enters the chamber and flows into the wastewater collection tank through longitudinal slits or openings (not shown) located in the bottom of the chamber. The droplets are collected in the wastewater collection tank 74 by gravity. A wastewater outlet 75 is connected to the bottom of the wastewater collection tank. The wastewater outlet 75 is connected to a controllable wastewater valve 62 downstream of the wastewater outlet 75. The wastewater valve 75 is then connected downstream of the valve 75 to onboard equipment (not shown) for collecting wastewater on board the vessel that is not safe to pump overboard, such as a bilge tank or other tank.

[0088] FIG. 7 illustrates an EGR scrubber 700′ having multiple perforated plates 730-734 according to an exemplary embodiment. The EGR scrubber chamber 760 is shown having a cylindrical shape suggested by a central axis B. Additionally, FIG. 7 illustrates an alternative mounting of a first perforated plate 730, a second perforated plate 731, a third perforated plate 732, a fourth perforated plate 733, and a fifth perforated plate 734 within the chamber 760 of the EGR scrubber 700′. The first perforated plate 730 and the second perforated plate 731 are spaced a distance d from each other. The distance d is measured from an orthogonal plane from the first perforated plate 730 to the second perforated plate 731. Additionally, the first perforated plate 730 is shown having four openings 78′, and the second perforated plate 731 is shown having seven openings 78″. The openings 78' in the first perforated plate are radially offset from the openings 78'' in the second perforated plate 731. Figure 7 further shows that the third perforated plate 732 is spaced a distance d2 from the second perforated plate 731. The distance d2 is shown to be less than the distance d between the first perforated plate 730 and the second perforated plate 731.

[0089] FIG. 7 also shows that the fourth perforated plate 733 and the fifth perforated plate 734 are positioned at an angle α from the first perforated plate 730, the second perforated plate 731, and the third perforated plate 732.

[0090] FIG. 8 illustrates the wastewater collection tank 74 of the EGR scrubber 70 disclosed in FIGS. 1, 3-7, according to an exemplary embodiment. The wastewater collection tank 74 includes an outlet 75 and a wastewater valve 62 disposed downstream of the outlet 75. The control unit 200 of FIG. 1 is also shown in FIG. 8. The control unit 200 is electrically connected to a wastewater level sensor 91, which indicates a low wastewater level 91′ in the wastewater collection tank 74 of the EGR scrubber 70. The control unit is also electrically connected to a wastewater level sensor 92, which indicates a high wastewater level 92′ in the wastewater collection tank 74 of the EGR scrubber 70. For illustrative purposes, an exemplary water level 90 is also shown in FIG. 8.

[0091] The control unit 200 is configured to control the controllable wastewater valve 62 to an open position that allows wastewater to be removed from the wastewater collection tank 74 when the wastewater level is above the high wastewater level 92′. Additionally, the control unit is configured to control the wastewater valve 62 to a closed position when the wastewater level is below the low wastewater level 91′.

[0092] 8 further shows a critical wastewater level sensor 93, which indicates that the wastewater level is above a critical level 93'. When the control unit 200 receives a signal from the critical wastewater level sensor 93 that the wastewater level is above a critical level, the control unit 200, or software running on the control unit, isolates the EGR arrangement of FIG. 1 from the engine by closing EGR valve 51 and EGR valve 52. The control unit 200 also operates one or more water valves 61, 62 to close or stop the injection of water through the nozzle(s) of the water spray device 60.

[0093] Figure 9 shows examples of different types of perforated plates used in EGR scrubbers. Figure 9a shows a square-shaped plate 900 including a plurality of equally sized openings 908 arranged in a first pattern. All openings are shown to have the same or equal diameter. The openings are arranged in a first group 918 and a second group 919 of openings, with the openings 908 in the first group 918 alternating with the openings 908 in the second group 919.

[0094] 9b shows a perforated plate 920 with apertures 921-923 having different diameters. The apertures are arranged in a first group 929, a second group 930 and a third group 931.

[0095] 9c shows a circular perforated plate 940 that includes a plurality of apertures 948, each having the same or equal diameter. The apertures 948 are equally spaced within the perforated plate 940.

[0096] Figure 9d shows a circular apertured plate 960 including a plurality of apertures 968, 969. The apertured plate 960 includes a plurality of first apertures 969 having a first diameter and four apertures 968 having a diameter larger than the diameter of the first apertures 969. While Figures 9a-9d show apertures having a round shape, other shapes are possible, such as a square, star, or hexagonal shape. Additionally, plates with different patterns of apertures may be incorporated into a stack of apertured plates.

[0097] FIG. 10 illustrates the EGR arrangement 100 of FIG. 1 with a single EGR scrubber 70 and water spray device 60 disposed within an outer housing 111. The outer housing 111 includes an inlet 112 and an outlet 110. The inlet 112 is configured to receive a flow of cooling fluid, such as water or air, from a pump or fan (not shown) disposed external to the housing. The cooling fluid enters from the pump or fan, passes through the inlet 112, passes through the interior volume of the housing, and exits through the outlet 110. As the cooling fluid flows through the housing 111, the outer surfaces of the EGR scrubber or piping are cooled, further helping to cool the exhaust gases flowing through the EGR conduit and EGR scrubber 70. The outlet 110 of the housing 111 is then connected to piping (not shown) to a point or location outside the room or space in which the engine and EGR arrangement are located, such as ambient air.

Claims

1. An exhaust gas recirculation (EGR) arrangement (100) for a single or multi-cylinder four-stroke compression ignition engine, said EGR arrangement (100) comprising: An exhaust gas conduit having an EGR inlet (41) and an EGR outlet (42), the EGR inlet (41) comprises an engine exhaust manifold (31) for an engine cylinder bank, the engine exhaust manifold (31) for receiving a portion of the combustion gases from at least one cylinder of the cylinder bank, and the EGR outlet (42) is an exhaust gas conduit arranged to be connected to an intake of the engine arranged upstream of a turbocharger compressor inlet; at least one controllable EGR valve (51) arranged in fluid communication between the EGR inlet (41) and the EGR outlet (42); an EGR scrubber (70) disposed in the exhaust gas conduit in fluid communication between the EGR valve (51) and the EGR outlet (42), the EGR scrubber (70) being a water scrubber comprising a chamber (76) having a chamber inlet (71) and a chamber outlet (72), the chamber outlet (72) being disposed downstream of and in fluid communication with the chamber inlet (71); at least one water spray device (60) comprising at least one nozzle (64), the at least one water spray device (60) being arranged downstream of the EGR valve (51) and upstream of the chamber outlet (72), the at least one water spray device (60) being connectable to a pressurized water source and configured to inject pressurized water into the exhaust gas conduit through the at least one nozzle (64) to increase a liquid surface area of ​​the injected water that contacts exhaust gas in the exhaust gas conduit; An exhaust gas recirculation (EGR) arrangement (100) comprising:

2. 2. The exhaust gas recirculation (EGR) arrangement (100) of claim 1, wherein at least one water spray device (60) is disposed upstream of the EGR scrubber (70) and downstream of the EGR valve (51) for spraying water into the exhaust gas conduit.

3. 3. An exhaust gas recirculation (EGR) arrangement (100) according to any one of claims 1 to 2, wherein at least one water spray device (60) is arranged to spray water inside the chamber (76).

4. 4. An exhaust gas recirculation (EGR) arrangement (100) according to any one of claims 1 to 3, wherein at least one of the water spray devices (60) comprises a controllable water valve (61) for controlling the pressure and / or flow rate of water supplied to the nozzle (64).

5. 5. The exhaust gas recirculation (EGR) arrangement (100) of claim 1, wherein the EGR scrubber (74) further comprises a wastewater collection tank (74) for collecting wastewater, and wherein at least one controllable wastewater valve (62) is in fluid communication with a wastewater outlet (75) of the wastewater collection tank (74), the wastewater valve (62) being configured to control removal of collected wastewater containing unburned particles, such as soot, from the chamber by opening the at least one wastewater valve (62).

6. 6. The exhaust gas recirculation (EGR) arrangement (100) of claim 1, wherein the chamber (76) comprises at least one perforated plate (73) including a plurality of openings (78), the perforated plate being positioned inside the chamber (76) downstream of the at least one water spray device (60).

7. 7. The exhaust gas recirculation (EGR) arrangement (100) of claim 6, wherein the chamber (76) comprises a plurality of perforated plates (730, 731, 732), the perforated plates (730, 731, 732) being arranged in a stacked configuration with a distance (d, d2) between them.

8. 8. An exhaust gas recirculation (EGR) arrangement (100) according to claim 6-7, wherein the chamber comprises a plurality of perforated plates, and a first perforated plate (732) and a second perforated plate (734) are arranged at an angle (α) to each other.

9. 9. The exhaust gas recirculation (EGR) arrangement (100) of claim 6, wherein the chamber comprises a first perforated plate and a second perforated plate, and the diameter of the openings in the first perforated plate is the same as or different from the diameter of the openings in the second perforated plate.

10. 10. The exhaust gas recirculation (EGR) arrangement (100) of claim 6, wherein the chamber comprises a first perforated plate and a second perforated plate, the openings in the first perforated plate being radially offset from the openings in the second perforated plate.

11. 11. The exhaust gas recirculation (EGR) arrangement (100) according to any one of claims 1 to 10, further comprising a control unit (200), the control unit (200) being electrically connected to the EGR valve (51) and configured to control the EGR valve to assume a position for adjusting the amount of exhaust gas recirculated from the EGR inlet to the EGR outlet based on an engine load signal.

12. 12. The exhaust gas recirculation (EGR) arrangement (100) of claim 11, further comprising at least one humidity sensor (81) disposed downstream of the EGR chamber for determining a moisture content in the exhaust gas flow, the at least one humidity sensor being electrically connected to the control unit.

13. 13. The exhaust gas recirculation (EGR) arrangement (100) of claim 11-12, further comprising at least one oxygen sensor (83) arranged in the exhaust gas conduit between the chamber and the EGR outlet, the oxygen sensor being arranged to determine an amount of oxygen in the exhaust gas flow, the oxygen sensor being electrically connected to the control unit.

14. 14. The exhaust gas recirculation (EGR) arrangement (100) of claim 11, further comprising at least one temperature sensor (82) arranged downstream of the EGR chamber and upstream of the EGR outlet, the temperature sensor being electrically connected to the control unit (200).

15. 15. The exhaust gas recirculation (EGR) arrangement (100) of claim 12, wherein the control unit (200) is configured to control a controllable water valve (61) to control the pressure and / or flow rate of water supplied to the water spray device (60) based on data from the sensors and / or based on the position of the EGR valve or an engine load signal.

16. 16. The exhaust gas recirculation (EGR) arrangement (100) of any one of claims 11 to 15, wherein the control unit (200) is further connected to the controllable wastewater valve (62) for controlling the wastewater valve to assume a position where wastewater can be removed from the chamber (76).

17. 17. The exhaust gas recirculation (EGR) arrangement (100) of claim 1, wherein at least one EGR scrubber (70) is disposed inside an outer housing (111), the outer housing having an inlet opening (112) and an outlet opening (110), and wherein a cooling fluid from outside the outer housing is supplied to the housing using at least one of a fan, a blower, or a pump to cool an outer surface of the at least one EGR scrubber, the cooling fluid passing through the inlet opening and the outer housing and exiting out of the outlet opening.

18. 18. The exhaust gas recirculation (EGR) arrangement (100) of claim 1, further comprising at least a second EGR scrubber (70′) arranged in fluid communication between the first EGR scrubber (70) and the EGR outlet (42).

19. 18. The exhaust gas recirculation (EGR) arrangement (100) of any one of claims 1 to 17, wherein the EGR arrangement further comprises a second EGR scrubber (70''), the second EGR scrubber (70'') being disposed between the EGR inlet (41) and the EGR outlet (42) and operating in parallel with the first EGR scrubber (70).

20. A four-stroke compression engine (1) comprising an exhaust gas recirculation arrangement (100, 100', 100'') according to any one of claims 1 to 19.

21. 21. A four-stroke compression engine according to claim 20, wherein the engine comprises at least one cylinder bank (10) and an exhaust manifold (31) attached to the cylinder bank, the EGR inlet (41) being connected to the exhaust manifold at a location upstream of an exhaust gas collection point (34), the collection point being a point within the exhaust manifold where exhaust gases from the engine cylinder banks join to form a common exhaust gas stream including exhaust gases from each cylinder (11, 12, 13, 14) of the engine cylinder bank (10).

22. A four-stroke compression engine according to claim 20, wherein the EGR inlets (41') are connected to individual cylinder engine exhaust gas runners (33') of the exhaust manifold (31').

23. 21. A four-stroke compression engine according to claim 20, wherein the exhaust manifold comprises a plurality of manifold inlets (33) connected to a corresponding number of engine exhaust ports and an exhaust manifold outlet (34) connected to the engine exhaust system, the EGR inlet (41) being connected to the exhaust manifold (31) upstream of the exhaust manifold outlet (34) and downstream of the plurality of manifold inlets (33).

24. A four-stroke compression engine according to any one of claims 20 to 23, wherein the EGR outlet (42) is connected to the engine intake upstream of the turbocompressor (22).

25. The four-stroke compression engine according to any one of claims 22 to 24, wherein the control unit (200) controls the EGR valve (51) to divert 5-10% of the combustion gases from the exhaust manifold (31) to the EGR inlet (41).

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