KR20200001353U - System and method for generating power onboard a ship - Google Patents

Abstract

Systems (1, 51) and methods for generating power on board a ship are provided. The system comprises a turbocharger 5 comprising an ammonia engine 3 arranged to produce exhaust gas and a turbine 21 and a compressor 23. The ammonia engine 3 has an exhaust gas outlet 25 and an exhaust gas inlet connected to recirculate the first part EG1 of the exhaust gas EG generated by the ammonia engine 3 back to the ammonia engine 3 (27). The turbine 21 is arranged to communicate with the ammonia engine 3 and to be rotated by the second portion EG2 of the exhaust gas EG produced by the ammonia engine 3. The compressor 23 is arranged to be driven by turbine rotation to pressurize the air, and communicates with the ammonia engine 3 to supply pressurized air to the ammonia engine. The system 3 is characterized in that it further comprises a scrubber 7 for cleaning and cooling the first part EG1 of the exhaust gas EG with a scrubber fluid SF. The scrubber 7 communicates with the ammonia engine 3 to receive the first portion EG1 of the exhaust gas EG from the ammonia engine 3. Further, the scrubber 7 communicates with the ammonia engine 3 to supply the ammonia engine 3 after cleaning and cooling the first portion EG1 of the exhaust gas EG.

Description

System and method for generating power on board a ship{SYSTEM AND METHOD FOR GENERATING POWER ONBOARD A SHIP}

The present invention relates to a system for generating power on board a ship. The invention also relates to a method for generating power on board a ship.

Large vessels are typically driven by marine engines operated by fuels such as heavy oil (HFO), diesel oil (DO) or liquefied natural gas (LNG). All of these fuels are carbon-based fossil fuels that emit carbon dioxide during combustion. A recent draft-ambition from IMO is that the marine industry must cut carbon dioxide emissions by 40% by 2030 and 70% by 2050.

An alternative fuel for marine engines is ammonia, and existing marine engines operating with fossil fuels typically alternatively with ammonia and ammonia-containing fuels, eg fuels containing a mixture of ammonia and fossil fuels. / Can be modified relatively easily to be additionally operable.

Ammonia has several advantages. Ammonia is already produced on an industrial scale worldwide in very large quantities with a well-established global distribution network. In addition, its production is based on the Haber-Bosch process, which can only be driven by electricity. In addition, ammonia can be stored in liquid form only at -33°C compared to -162°C for LNG, which is advantageous when stored for a long time. Finally, there is no carbon dioxide emissions when ammonia is burned, making it a suitable fuel to meet the aspirations of IMO.

However, ammonia also has a disadvantage, one of which is that its energy density is only about half that of fossil fuels. In addition, when ammonia is burned in an engine, it will not only be corrosive, but also produce nitric acid, which is harmful to the environment. However, nitric acid emissions reduce the concentration of oxygen in the combustion air, which in turn can be reduced by providing the engine with an Exhaust Gas Recirculation (EGR) system that reduces the formation of nitric acid. The low temperature of the recycled gas lowers the combustion temperature in the engine, thus reducing the formation of nitric acid. Therefore, the exhaust gas to be recirculated must be cooled before being guided into the engine.

US 9,347,366 discloses an ammonia engine provided with an EGR system. The exhaust gas to be recirculated is cooled by spraying liquid ammonia therein. These engines may be associated with the risk of ammonia leakage. In addition, the cooling effect available depends on the amount of ammonia injected. Injecting an insufficient amount of ammonia can result in insufficient cooling of the exhaust gas to be recycled.

An object of the present invention is to provide a system and method for generating power on board a ship by ammonia engine and exhaust gas recirculation, which at least partially solves the above-mentioned problems. The basic concept of the present invention is to provide a wet scrubber that allows exhaust gas to be recirculated to cool the exhaust gas sufficiently for recirculation. Due to the scrubber, sufficient cooling of the exhaust gas to be circulated can be ensured. In addition, since the equipment for injection of ammonia into the exhaust gas to be recycled is not required, the risk of ammonia leakage is greatly reduced. Systems and methods according to the present invention are defined in the appended claims and described below.

As described above, when ammonia is burned in the engine, nitric acid is produced, and exhaust gas recirculation is applied to reduce the amount of nitric acid produced. Exhaust gases from combustion typically also contain particulate matter such as soot, oil and heavy metals. Particulate matter is not due to ammonia, but due to, for example, the engine's lubricant. If the fuel for operating the ammonia engine also contains sulfur, the exhaust gas will also contain sulfur oxides (SO _X ). By passing the exhaust gas to be recirculated through the scrubber whose interior is flushed with the scrubber fluid, contaminants in the exhaust gas are trapped in the scrubber fluid, which reduces the effect of the final exhaust gas on the environment.

The system according to the present invention includes an ammonia engine arranged to generate exhaust gas to generate power on board the ship. The system further includes a turbocharger comprising a turbine and a compressor. The ammonia engine includes an exhaust gas outlet and an exhaust gas inlet connected to indirectly recirculate the first portion of the exhaust gas produced by the ammonia engine back to the ammonia engine. The turbine is arranged to communicate with the ammonia engine and to be rotated by the second portion of the exhaust gas produced by the ammonia engine. The compressor is arranged to be driven by turbine rotation to pressurize the air, and the compressor communicates with the ammonia engine to supply pressurized air to the ammonia engine. The system is further characterized by further comprising a scrubber for cleaning and cooling at least the first portion of the exhaust gas with a scrubber fluid. The scrubber communicates with the ammonia engine to receive at least the first portion of exhaust gas from the ammonia engine. Further, the scrubber communicates with the ammonia engine to supply the ammonia engine after cleaning and cooling the first portion of the exhaust gas.

An ammonia engine means an engine that can be driven by fuel containing at least ammonia and/or ammonia, but possibly also by other fuels.

Throughout the text, when it is stated that something is communicating with something else, they can communicate directly or indirectly with each other.

The first portion can make up 0 to 100% of the exhaust gas, which can change over time. Typically, the first portion should constitute 30 to 40% of the exhaust gas to enable meeting current regulations.

The second portion of the exhaust gas may or may not include the first portion of the exhaust gas. When the second part of the exhaust gas comprises a first part of the exhaust gas, the scrubber can be arranged to receive, clean and cool the second part of the exhaust gas.

The second portion of the exhaust gas may or may not leave the ammonia engine through the exhaust gas outlet.

Since at least a first portion of the exhaust gas arranged to be recycled is supplied through a scrubber, the first portion is cooled sufficiently effectively to be recycled. In addition, when the fuel generating the exhaust gas must contain sulfur, the first part is washed with a scrubber fluid, so that particulate matter and sulfur oxides are cleaned.

There are various types of scrubbers. One type of scrubber is a so-called open loop scrubber that uses seawater to clean and cool the exhaust gas. Then, seawater is once supplied from the sea through a scrubber for absorption of pollutants from the exhaust gas and cooling of the exhaust gas, and then seawater is discharged back to the sea. Other types of scrubbers use circulating fresh water or seawater, possibly combined with an alkaline agent such as sodium hydroxide (NaOH), sodium carbonate (Na ₂ CO ₃ ) or magnesium oxide (MgO), to clean and cool the exhaust gas. It is a so-called closed loop scrubber to use. In such scrubbers, the amount of particulate matter and possibly salts in circulating fresh water or sea water is gradually increasing. Thus, to control the quality of the circulating fresh water or sea water, a small amount of which can be extracted occasionally or continuously to be recycled, stored on the vessel, or cleaned before being discharged out of the vessel.

The system according to the present invention can be configured such that the scrubber fluid inlet of the scrubber is arranged in communication with the scrubber fluid outlet of the scrubber. Thereby, recirculation of the scrubber fluid, ie closed loop scrubber, can be enabled. Closed-loop scrubbers, especially freshwater closed-loop scrubbers, may be particularly suitable for systems with EGR function because the scrubber fluid will not contain chlorides from seawater that can cause corrosion on the components of the rest of the system.

The system may further include a circulation tank, the circulation tank communicating with a scrubber, eg, the scrubber fluid outlet of the scrubber, to receive scrubber fluid from the scrubber after cleaning and cooling the first portion of the exhaust gas, and the circulation tank Is in communication with a scrubber, for example, the scrubber fluid inlet of the scrubber to supply the scrubber fluid to the scrubber.

The system can further include a heat exchanger arranged downstream of the scrubber fluid outlet and upstream of the scrubber fluid inlet. Thereby, the scrubber fluid can be cooled during recirculation, ie after passage through the scrubber and before other passage through the scrubber, to enable sufficient cooling of the first portion of the exhaust gas. Various cooling media of the heat exchanger are possible, for example seawater.

The system can further include a water cleaning unit. The water scrubbing unit, in order to receive the scrubber fluid after washing and cooling the first portion of the exhaust gas, and to separate it into first and second splits, the scrubber and possibly a circulation tank, if present It can be arranged in communication with the circulation tank. The second split is more contaminated than the first split. The first fraction can be fed directly or indirectly back to the scrubber, for example, through a circulation tank if a circulation tank is present, or into a storage tank, or can be discharged out of the vessel, Replenishment of scrubber fluid may be required. Thereby, the scrubber fluid in the system can be kept clean enough for proper operation of the scrubber.

The water washing unit can include a centrifugal separator, such as a high-speed separator, decanter, or a combination thereof, and/or a membrane filter.

According to one embodiment, the scrubber is arranged downstream of the turbine, and the second part of the exhaust gas comprises a first part of the exhaust gas. Thereby, the second part of the exhaust gas, including the first part of the exhaust gas, at least before the first part of the exhaust gas is cleaned and cooled by a scrubber and the first part of such exhaust gas is recycled to the ammonia engine, It can be supplied through a turbine. This embodiment enables the so-called low pressure EGR. The advantage of low pressure EGR is that the existing wet scrubber can be modified relatively easily to operate in low pressure EGR type systems.

In the case of the above embodiment, the third portion of the exhaust gas minus the first portion from the second portion can be released after passing through the turbine, that is, without passing through the scrubber. Alternatively, the scrubber may be arranged to also receive the second portion of the exhaust gas, including the first portion of the exhaust gas, ie the third portion of the exhaust gas, and to wash and cool it with scrubber fluid. Whether the third part of the exhaust gas passes through the scrubber or not can depend, for example, on which fuel is used to operate the ammonia engine. For example, when a mixture of HFO and ammonia is used as fuel, the third portion of the exhaust gas can pass through a scrubber. However, when a mixture of DO and ammonia is used as fuel, the third part of the exhaust gas may not pass through the scrubber.

As an alternative to the above embodiment, after the first part of the exhaust gas is separated from the second part of the exhaust gas, the first part of the exhaust gas may be separate from the second part of the exhaust gas, instead the scrubber is a turbine It can be arranged upstream. Thereby, only the second part of the exhaust gas can be supplied through the turbine, while only the first part of the exhaust gas is cleaned and cooled by a scrubber and recycled to the ammonia engine. This embodiment enables the so-called high pressure EGR. The advantage of high pressure EGR is that if particulate matter and sulfur oxides are present in the exhaust gas, this can be prevented from corroding or blocking some components of the system, which will be further described below.

The system can further include a fan or EGR fan arranged to tow the first portion of the exhaust gas through the scrubber into the ammonia engine. By the fan, the pressure of the exhaust gas to be recycled can be increased, and the flow of the exhaust gas to be recycled can be controlled. The fan can be arranged at various locations within the system, for example depending on the fuel used to drive the ammonia engine. For example, if the fuel is relatively dirty, the fan can be arranged before or upstream of the scrubber so that exhaust gas is supplied through the fan before being cooled in the scrubber. Thereby, deposits of particulate matter inside the fan can be minimized. On the other hand, if the fuel is relatively clean, the fan may be arranged after or after the scrubber so that the exhaust gas is supplied through the fan after the exhaust gas is cooled in the scrubber. This downstream fan can handle more exhaust gas flow than the upstream fan because the exhaust gas passing through is cooler and thus has less volumetric burden. Furthermore, these downstream fans may be less "sophisticated" than the upstream fans because their components are subjected to lower temperatures.

According to the present invention, a method for generating power on board a ship is a step of operating an ammonia engine, wherein an exhaust gas is generated by this operation, and a first portion of the exhaust gas generated by the ammonia engine is ammonia engine It includes the step of recycling. The method comprises supplying a second portion of the exhaust gas produced by the ammonia engine to a turbine of a turbocharger to rotate it, providing power from turbine rotation to pressurize the air to a compressor of the turbocharger, and And supplying pressurized air to the ammonia engine. The method comprises supplying a first portion of the exhaust gas produced by the ammonia engine to the scrubber, with a scrubber fluid, washing and cooling the first portion of the exhaust gas in the scrubber, and from the scrubber after washing and cooling. And recirculating the first portion of the exhaust gas to the ammonia engine. Therefore, according to the present invention, recirculation of the first portion of the exhaust gas is achieved after the first portion is cleaned and cooled by a scrubber.

The scrubber fluid inlet of the scrubber may be arranged in communication with the scrubber fluid outlet of the scrubber, and the method may further include recirculating the scrubber fluid through the scrubber.

The method may further include cooling the scrubber fluid downstream of the scrubber fluid outlet and upstream of the scrubber fluid inlet in the heat exchanger.

The method comprises using a portion of the scrubber fluid for cleaning and cooling the first portion of the exhaust gas and then supplying it from the scrubber to the water washing unit, and the portion of the scrubber fluid, in the water washing unit, is first divided Separating into water and a second partition, the second partition may further include a separation step, which is more contaminated than the first partition.

The second portion of the exhaust gas produced by the ammonia engine may include the first portion of the exhaust gas produced by the ammonia engine. Further, the method may further include supplying the second portion of the exhaust gas to the turbine before supplying the first portion of the exhaust gas to the scrubber. The complete second portion of the exhaust gas, as well as the first portion, may or may not be received, cleaned, and cooled by a scrubber.

Alternatively, the first portion of the exhaust gas produced by the ammonia engine may be separate from the second portion of the exhaust gas produced by the ammonia engine. Further, the method may further include separating the first and second parts of the exhaust gas from each other before supplying the first part to the scrubber and the second part to the turbine.

The advantages described above of the various embodiments of the system according to the invention are also provided for the corresponding various embodiments of the method according to the invention.

Other objects, features, aspects and advantages of the present invention will become apparent from the following detailed description and drawings.

The present invention will now be described in more detail with reference to the attached schematic.
1 is a block diagram schematically showing a system for generating power on board a ship.
2 is a flow chart showing a method for generating power on board a ship by the system according to FIG. 1.
3 is a block diagram schematically showing an alternative system for generating power on board a ship.
4 is a flow chart showing a method for generating power on board a ship by the system according to FIG. 3.

1 shows a system 1 for generating power on board a ship (not shown). This includes engine 3, turbocharger 5, scrubber 7, circulation tank 9, plate heat exchanger 11, water separator unit 13 in the form of a high-speed separator, sludge tank 15, chemical administration It includes a unit 17, an EGR fan 18 and an air cooler 19. Again, the turbocharger 5 includes a turbine 21 and a compressor 23, the engine 3 includes an exhaust gas outlet 25 and an exhaust gas inlet 27, and the scrubber 7 is a scrubber fluid It includes an inlet 29 and a scrubber fluid outlet 31. The scrubber 7 is based on random or structured packing, sprayers, trays or combinations thereof. This works in a conventional way, which is not described further here.

2 shows a method for generating power by the system 1. The engine 3 is driven by a mixture of HFO and ammonia, that is, the engine is an ammonia engine, and generates exhaust gas (EG) (step A). As described further below, the system 1 is arranged to recycle the first portion EG1 of the exhaust gas EG to the engine 3 to reduce nitric acid emissions. Here, the second part EG2 of the exhaust gas EG which is all exhaust gas and thus includes the first part EG1 of the exhaust gas is supplied from the engine 3 to the turbine 21 to rotate the turbine (step B ). The rotation of the turbine 21 is used as power by the compressor 23 to pressurize and compress the air taken from the outside (step C). The pressurized compressed air is cooled by the air cooler 19 before being supplied to the engine 3 (step E) (step D). When the exhaust gas passes through the turbine 21, the exhaust gas is supplied to the scrubber 7 by the EGR fan 18 (step F). Inside the scrubber 7, the exhaust gas, which is still all exhaust gas, is cleaned and cooled (step G) by a scrubber fluid (SF) in the form of fresh water containing an alkaline agent such as sodium hydroxide (NaOH). The scrubber fluid SF is supplied from the circulation tank 9 through the heat exchanger 11 to the scrubber 7 through the scrubber fluid inlet 29 of the scrubber. Inside the scrubber 17, the scrubber fluid SF cools the exhaust gas and absorbs contaminants therefrom to clean the exhaust gas, wherein the scrubber fluid SF is again circulated through the scrubber fluid outlet 31 to the circulating tank 9 ). Therefore, since the scrubber fluid inlet 29 communicates indirectly with the scrubber fluid outlet 31, ie through the circulation tank 9 and the heat exchanger 11, the scrubber fluid SF is recirculated through the scrubber 7 (Step H). During recirculation, the scrubber fluid SF is cooled by the heat exchanger 11 to allow sufficient cooling of the exhaust gas in the scrubber 7 (step I). Sea water is used as a cooling medium for heat exchangers.

When the scrubber fluid SF is recycled through the scrubber 7, the scrubber fluid becomes more and more contaminated. To ensure efficient operation of the scrubber 7, the scrubber fluid must not be excessively contaminated. Accordingly, a portion of the scrubber fluid SF is continuously pumped from the circulation tank 9 to the water washing unit 13 to be cleaned (step J). To ensure a sufficient amount of scrubber fluid in the circulation tank 9, the scrubber fluid may have to be replenished with scrubber fluid to compensate for pumping from the scrubber fluid. When the scrubber fluid cools the exhaust gas, water vapor in the exhaust gas can condense, which is an automatic continuous replenishment of the scrubber fluid and possibly also an excess amount requiring the scrubber fluid to be extracted into the water cleaning unit 13. Can cause scrubber fluid. In addition, scrubber fluid replenishment may involve the addition of clean fresh water from outside the system 1. In addition, “internal” replenishment of the scrubber fluid can occur by returning the scrubber fluid to the circulation tank 9 after washing as described further below.

The water washing unit 13 separates this part of the scrubber fluid SF into first and second partitions (step K). The second fraction, which is more contaminated than the first fraction, is fed to the sludge tank 15 (step L). The first fraction is fed back to the circulation tank 9 to bring the “internal” replenishment of the scrubber fluid, or to the storage tank (not shown), or discharged (step M).

An alkaline agent for adjusting the scrubber fluid pH to 6.5, here a chemical containing NaOH is supplied to the scrubber fluid SF in the circulation tank 9 by a chemical dosing unit 17 (step N).

After the cleaned and cooled exhaust gas leaves the scrubber 7, the first portion EG1 of the exhaust gas is supplied to the compressor 23, pressurized and compressed (step O), and then supplied to the cooler 19 to cool ( Step P) becomes. Also, the first portion EG1 of the exhaust gas is fed back to the engine 3 or recycled (step Q). Thus, the exhaust gas outlet 25 communicates indirectly with the exhaust gas inlet 27 to enable exhaust gas recirculation, i.e. through the turbine 21, the scrubber 7, the compressor 23 and the cooler 19. . On the one hand, the first part EG1 of the exhaust gas is compressed, cooled and supplied to the engine (steps O, P and Q), and on the other hand, the air taken from the outside is compressed, cooled and supplied to the engine (step C) , D and E) are done simultaneously, ie for the mixture of the external air and the first part of the exhaust gas. At the same time, the third portion EG3 of the exhaust gas minus the first portion EG1 from the second portion EG2 of the exhaust gas is discharged from the system 1 (step R).

In the system 1, the second part EG2 of the exhaust gas is all exhaust gas, that is, the second part EG2 of the exhaust gas includes the first part EG1 of the exhaust gas. Therefore, all the exhaust gas is used to rotate the turbine 21, and all the exhaust gas is cleaned and cooled by the scrubber 7. After the scrubber 7, the second part EG2 of the exhaust gas, that is, both are divided into first and third parts EG1 and EG3. The first portion EG1 is recirculated to the engine 3 while the third portion EG3 is discharged from the system 1. Thus, the system 1 is of the so-called low pressure type. The disadvantage of the low pressure system may be that the first part of the exhaust gas EG1, in particular the contaminants contained therein, can be supplied through the cooler 19 to cause corrosion of the cooler and deposits in the cooler.

According to an alternative embodiment, the scrubber 7 cools only the first part EG1 of the exhaust gas and, in particular, when the ammonia engine 3 is driven by cleaner fuel such as pure ammonia or a mixture of ammonia and DO. Can be arranged to wash. And, the second part EG2 of the exhaust gas, that is, all can be divided into the first and third parts EG1 and EG3 after the turbine 21 but before the scrubber 7, wherein the third part ( EG3) can be released from the system.

3 shows another system 51 for generating power on board a ship (not shown). This includes engine 3, turbocharger 5, scrubber 7, circulation tank 9, plate heat exchanger 11, water separator unit 13 in the form of a high-speed separator, sludge tank 15, chemical administration Unit 17 and air cooler 19 are included. Again, the turbocharger 5 includes a turbine 21 and a compressor 23, the engine 3 includes an exhaust gas outlet 25 and an exhaust gas inlet 27, and the scrubber 7 is a scrubber fluid It includes an inlet 29 and a scrubber fluid outlet 31. Like the scrubbers above, these scrubbers 7 are based on random or structured packing, sprayers, trays or combinations thereof. This works in a conventional way, which is not described further here. 4 shows a method for generating power by system 51. The engine 3 is driven by a mixture of HFO and ammonia, that is, the engine is an ammonia engine, and generates exhaust gas EG (step A). As described further below, system 51 is arranged to recycle the first portion EG1 of exhaust gas EG to engine 3 to reduce nitric acid emissions. Downstream of the engine 3, the exhaust gas EG is divided into a first part EG1 and a second part EG2 of the exhaust gas. Thus, here, the first and second portions EG1 and EG2 are separate portions of the exhaust gas EG. The second portion EG2 of the exhaust gas EG is supplied from the engine 3 to the turbine 21 to rotate it (step B). The rotation of the turbine 21 is used as power by the compressor 23 to pressurize and compress the air taken from the outside (step C). The pressurized compressed air is cooled by the air cooler 19 before being supplied to the engine 3 (step E) (step D). The first portion EG1 of the exhaust gas EG is supplied to the scrubber 7 (step F). Inside the scrubber 7, the first portion EG1 of the exhaust gas is washed and cooled (step G) with a scrubber fluid SF in the form of fresh water containing an alkaline agent such as sodium hydroxide (NaOH). The scrubber fluid SF is supplied from the circulation tank 9 to the scrubber 7 via the heat exchanger 11 through the scrubber fluid inlet 29 of the scrubber. Inside the scrubber 17, the scrubber fluid SF cools the exhaust gas and absorbs contaminants therefrom to clean the exhaust gas, wherein the scrubber fluid SF flows back through the scrubber fluid outlet 31 to the circulating tank 9 ). Therefore, since the scrubber fluid inlet 29 communicates indirectly with the scrubber fluid outlet 31, ie through the circulation tank 9 and the heat exchanger 11, the scrubber fluid SF is recirculated through the scrubber 7 (Step H). During recirculation, the scrubber fluid SF is cooled by the heat exchanger 11 to allow sufficient cooling of the exhaust gas in the scrubber 7 (step I).

When the scrubber fluid SF is recycled through the scrubber 7, the scrubber fluid becomes more and more contaminated. To ensure efficient operation of the scrubber 7, the scrubber fluid must not be excessively contaminated. Accordingly, a portion of the scrubber fluid SF is continuously pumped from the circulation tank 9 to the water washing unit 13 to be cleaned (step J). To ensure a sufficient amount of scrubber fluid in the circulation tank 9, the scrubber fluid may have to be replenished with scrubber fluid to compensate for pumping from the scrubber fluid. When the scrubber fluid cools the exhaust gas, water vapor in the exhaust gas can condense, which is an automatic continuous replenishment of the scrubber fluid and possibly also an excess amount requiring the scrubber fluid to be extracted into the water cleaning unit 13. Can cause scrubber fluid. In addition, scrubber fluid replenishment may involve the addition of clean fresh water from outside the system 1. In addition, “internal” replenishment of the scrubber fluid can occur by returning the scrubber fluid to the circulation tank 9 after washing as described further below.

The water washing unit 13 separates this part of the scrubber fluid SF into first and second partitions (step K). The second fraction, which is more contaminated than the first fraction, is fed to the sludge tank 15 (step L). The first fraction is fed back to the circulation tank 9 to bring the “internal” replenishment of the scrubber fluid, or to the storage tank (not shown), or discharged (step M).

An alkaline agent for adjusting the scrubber fluid pH to 6.5, here a chemical containing NaOH is supplied to the scrubber fluid SF in the circulation tank 9 by a chemical dosing unit 17 (step N).

After the cleaned and cooled first portion EG1 of the exhaust gas leaves the scrubber 7, it is fed or recycled back to the engine 3 (step Q). Thus, the exhaust gas outlet 25 communicates indirectly with the exhaust gas inlet 27 to enable exhaust gas recirculation, ie through the scrubber 7. On the one hand, the supply of the first portion EG1 to the engine (step Q) and on the other hand the supply of cooled pressurized air taken from the outside to the engine (step E), is a single operation In, ie, it is carried out simultaneously for the mixture of external air and the first part of the exhaust gas. When the second portion EG2 of the exhaust gas passes through the turbine 21, it is discharged from the system 51 (step R).

In the system 51, the second part EG2 of the exhaust gas does not include the first part EG1 of the exhaust gas. Therefore, only the second portion EG2 of the exhaust gas is used to rotate the turbine 21 before being discharged from the system 57. Further, only the first portion EG1 of the exhaust gas is cleaned and cooled by the scrubber 7 before being recycled to the engine 3. Thus, the system 51 is of the so-called high pressure type. The advantage of this system is that the first part EG1 of the exhaust gas EG, especially the contaminants contained therein, does not pass through the cooler 19, and can reduce the risk of corrosion and arrest of the cooler. .

According to an alternative embodiment, the system 57 may include other scrubbers arranged downstream of the turbine 21 to clean the second portion EG2 of the exhaust gas before being released. These additional scrubbers can involve separate circulation tanks, heat exchangers, chemical dosing units, water scrubbing units and sludge tanks, or can be shared with one or more scrubbers 7 of these components.

In all of the systems described above, the scrubber may remove contaminants from the exhaust gas, making it less harmful to the environment, as well as effectively cooling the exhaust gas to enable recirculation of the exhaust gas. Exhaust gas recirculation will reduce the oxygen concentration in the combustion air of the engine, which in turn will reduce the formation of nitric acid in the exhaust gas.

The components of the system described above are connected by suitable piping to enable them to communicate in the manner specified above and to allow the flow specified above between components. The piping design can be different between various embodiments of the invention. For example, in an embodiment of the system, which is an alternative to that shown in FIG. 1, the first portion of the exhaust gas and air can be supplied to the engine through different, non-shared piping from the compressor. Further, the first fraction of scrubber fluid may be supplied from the water washing unit to a circulation tank through a separate pipe. Similarly, the first and third portions EG1 and EG3 of the exhaust gas may leave the scrubber through separate pipes. As another example, in an embodiment of an alternative system to that shown in FIG. 3, the first portion of the exhaust gas and air may be supplied to the engine through completely different piping from the cooler and scrubber, respectively. Also, the first and second portions of the exhaust gas EG1 and EG2 may leave the engine through separate piping.

The above-described embodiment of the present invention should be seen only as an example. Those skilled in the art recognize that the discussed embodiments can be modified in a number of ways within the concept of the present invention.

In the embodiment described above, the first fraction of scrubber fluid is supplied from the water scrubbing unit to the circulation tank, discharged out of the vessel, or supplied to the storage tank. The first fraction can be further cleaned with a membrane, for example, before being fed to a circulation tank or storage tank or before being discharged out of the vessel. Whether the first fraction is fed out of the circulation tank, storage tank or vessel can depend on its quality, the surroundings of the vessel, and the amount of scrubber fluid. Further, the scrubber fluid need not be continuously supplied from the circulation tank to the water washing unit. Supply can be discontinuous. It can also change over time.

The system described above may include additional components to properly operate them, such as pumps, valves, sensors, water analysis units, control units, and the like. As an example, the system can include a pH meter or sensor between the scrubber and the circulation tank to measure the pH of the scrubber fluid. This pH meter can communicate with the chemical dosing unit 17. As another example, the system can include an EGR valve to control the flow of recirculating exhaust gas.

Alternative positioning of system components relative to each other is possible. For example, the chemical dosing unit can be arranged between the scrubber and the circulation tank or heat exchanger, or between the circulation tank and the heat exchanger. In other embodiments, it may be possible to exclude the chemical dosing unit, for example when the ammonia engine is driven by cleaner fuels such as pure ammonia or a mixture of DO and ammonia. Also, if the ammonia engine is driven by cleaner fuel, the EGR fan can be arranged after the scrubber or downstream.

The chemicals supplied by the chemical administration unit may contain other/additional chemicals other than alkaline agents such as flocculants and/or coagulants. Additionally, the water scrubbing unit may further comprise an agglomeration unit arranged upstream, ie before the high-speed separator and downstream, ie after the chemical dosing unit. This agglomeration unit can be arranged to hold the scrubber fluid before being accommodated by a high speed separator to allow sufficient time for agglomeration. Thereby, the efficiency of the high-speed separator can be optimized.

The system according to the present invention need not include a circulation tank. Thus, in an alternative embodiment, the water scrubbing unit can be arranged to supply the first fraction to the scrubber instead of the circulation tank. In other alternative embodiments, the system may be of an open loop type so as not to include recirculation or return of the scrubber fluid.

The scrubber fluid need not include fresh water and alkaline agents, but instead may contain sea water and alkaline agents or combinations thereof. However, the use of seawater in the scrubber fluid may require the use of certain materials for system components to avoid corrosion problems.

It should be noted that the steps of the method according to the present invention have been named steps A, B, etc. for identification purposes only. Therefore, the steps need not be performed in a specific order step A, step B, or the like. Also, one or more steps may be excluded from alternative embodiments.

It should be noted that the qualifiers 1, 2, 3, etc. are used herein only for discrimination purposes and are not intended to express any kind of specific order.

It should be noted that the description of details not related to the present invention has been omitted, and the drawings are merely illustrative and are not drawn to scale.

Claims (9)

A system (1, 51) for generating power on board a ship, comprising an ammonia engine (3) arranged to generate exhaust gas, and a turbocharger (5) comprising a turbine (21) and a compressor (23) , The ammonia engine 3 is connected to the exhaust gas outlet 25 connected to enable recirculation of the first portion EG1 of the exhaust gas EG generated by the ammonia engine 3 back to the ammonia engine 3 And an exhaust gas inlet 27, the turbine 21 communicating with the ammonia engine 3 and arranged to be rotated by the second portion EG2 of the exhaust gas EG generated by the ammonia engine 3 The compressor 23 is arranged to be driven by turbine rotation to pressurize the air, and the compressor 23 is in communication with the ammonia engine 3 to supply pressurized air to the ammonia engine 3, a system ( 1, 51, further comprising a scrubber (7) for cleaning and cooling the first portion (EG1) of the exhaust gas (EG) with a scrubber fluid (SF), the scrubber (7) is an ammonia engine (3 ) To communicate with the ammonia engine 3 to receive the first portion EG1 of the exhaust gas EG, and a scrubber 7 cleans the first portion EG1 of the exhaust gas EG and A system (1, 51) characterized in that it communicates with the ammonia engine (3) to supply it to the ammonia engine (3) after cooling. The system (1, 51) according to claim 1, wherein the scrubber fluid inlet (29) of the scrubber (7) is arranged in communication with the scrubber fluid outlet (31) of the scrubber (7). 3. The circulation tank (9) according to claim 2, further comprising a circulation tank (9) in communication with the scrubber (7) to receive the scrubber fluid (SF) from the scrubber (7) after cleaning and cooling. (9) is a system (1, 51) in communication with the scrubber (7) to supply the scrubber fluid (SF) to the scrubber (7). The system (1, 51) according to claim 2 or 3, further comprising a heat exchanger (11) arranged downstream of the scrubber fluid outlet (31) and upstream of the scrubber fluid inlet (29). Water arranged in communication with the scrubber (7) according to any one of claims 1 to 3 to receive the scrubber fluid (SF) after washing and cooling and to separate the scrubber fluid into first and second fractions. A system (1, 51) further comprising a cleaning unit (13), the second partition being more contaminated than the first partition. 4. The scrubber (7) is arranged downstream of the turbine (21 ), the second part (EG2) of the exhaust gas (EG) is the first of the exhaust gas (EG). System 1 comprising a portion EG1. The system (1) according to claim 6, wherein the scrubber (7) is arranged to receive the second portion (EG2) of the exhaust gas (EG) and to wash and cool it with the scrubber fluid (SF). 4. The scrubber (7) is arranged upstream of the turbine (21 ), the first part (EG1) of the exhaust gas (EG) is the second of the exhaust gas (EG). System 51 separate from the portion EG2. 4. A fan (18) according to any of the preceding claims, further comprising a fan (18) arranged to tow the first portion (EG1) of the exhaust gas (EG) through the scrubber (7) into the ammonia engine (3). System (1, 51).

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