DK201900097U3 - System for generating power on board a ship - Google Patents

Abstract

A system (1, 51) for generating power on board a ship is provided. The system comprises an ammonia engine (3) arranged to produce an exhaust gas, and a turbocharger (5) containing a turbine (21) and a compressor (23). The ammonia engine (3) contains an exhaust gas outlet (25) and an exhaust gas inlet (27) connected to allow recirculation of a first portion (EG1) of the exhaust gas (EG) produced by the ammonia engine (3) back to the ammonia engine (3). ). The turbine (21) is in communication with the ammonia engine (3) and arranged to be rotated by a 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 air and it is in communication with the ammonia motor (3) to supply the pressurized air to the ammonia motor. The system (3) is characterized in that it further comprises a scrubber (7) for washing and cooling the first portion (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) is in communication with the ammonia engine (3) to supply the first portion (EG1) of the exhaust gas (EG) to the ammonia engine (3) after cleaning and cooling it.

Description

SYSTEM FOR GENERATING POWER ONboard A SHIP

Technical area

The generation relates to a system for generating power on board a ship.

The background of the creation

Large vessels are typically powered by maritime engines that operate on fuels such as heavy fuel oil (HFO), diesel fuel (DO) or liquefied natural gas (LNG). These fuels are all carbon-based fossil fuels that emit carbon dioxide during combustion. The latest ambitions for a draft from the IMO are for the maritime industry to cut 40% of carbon dioxide emissions by 2030 and 70% by 2050.

An alternative fuel for maritime engines is ammonia, and existing fossil fuel maritime engines can typically be modified relatively easily so that instead they can / can be used with ammonia and ammonia-containing fuels such as fuel containing a mixture of ammonia and fossil fuel.

Ammonia has several benefits. It is already produced on an industrial scale around the world in very large quantities with a well-established global distribution network. Furthermore, its production is based on the Haber-Bosch process, which can only be run on electricity. In addition, ammonia can be stored in liquid form at only -33 degrees C compared to -162 degrees C for LNG, which is advantageous for long-term storage. Finally, there is no carbon dioxide emission when ammonia is incinerated, which makes ammonia a suitable fuel for meeting the IMO's ambitions.

However, ammonia also has disadvantages, one being that its energy density is approx. only half of that of fossil fuels. Furthermore, when combusted in an engine, ammonia will produce nitric acid, which is both harmful to the environment and corrosive. However, nitric acid emissions can be lowered by providing the engine with an exhaust gas recirculation (EGR) system to reduce the oxygen concentration in the combustion air, which in turn will reduce the formation of nitric acid. A low temperature of the recycled gas lowers the combustion temperature in the engine and thus the formation of nitric acid. Therefore, the exhaust gas to be recycled should be cooled before it is fed into the engine.

US 9,347,366 discloses an ammonia engine equipped with an EGR system. The exhaust gas to be recycled is cooled by the exhaust of liquid ammonia to it. Such an engine may be associated with a risk of ammonia leakage. Furthermore, the cooling effect available depends on the amount of injected ammonia. Injection of an insufficient amount of ammonia can result in insufficient cooling of the exhaust gas to be recirculated.

Summary

The object of the present invention is to provide a system and method for generating power on board a ship by means of an ammonia engine and exhaust gas recirculation, which at least partially solves the above problem. The basic concept behind the generation is to provide a wet scrubber through which the exhaust gas to be recirculated is passed through to sufficiently cool the exhaust gas for recycling. Due to the scrubber, sufficient cooling of the exhaust gas to be recirculated can be ensured. Furthermore, the risk of ammonia leakage is significantly reduced as no equipment for injecting ammonia into the exhaust gas to be recycled is needed. The system and method of manufacture is defined in the appended claims and set forth below.

As mentioned above, nitric acid is produced when ammonia is burned in an engine and exhaust gas recirculation is used to reduce the amount of nitric acid produced. The exhaust fumes from the combustion typically also contain particulate matter such as soot, oil and heavy metals. The particulate matter does not result from the ammonia, but from e.g. lubricating oil in the engine. If the fuel for driving the ammonia engine also contains sulfur, the exhaust gas will also contain sulfur oxides (SOX). By passing the exhaust gas to be recycled through a scrubber in which it is flushed with scrubber fluid, pollutants in the exhaust gas are trapped in the scrubber fluid which reduces the impact of the possibly released exhaust gas on the environment.

A system for generating power on board a ship comprises an ammonia engine which is arranged to produce an exhaust gas. It further comprises a turbocharger containing a turbine and a compressor. The ammonia engine contains an exhaust gas outlet and an exhaust gas inlet, which is indirectly connected to allow recirculation of a first portion of the exhaust gas produced by the ammonia engine back to the ammonia engine. The turbine is in communication with the ammonia engine and arranged to be rotated by a second portion of the exhaust gas produced by the ammonia engine. The compressor is arranged to be driven by turbine rotation to pressurize air, and the compressor is in communication with the ammonia motor to supply the pressurized air to the ammonia motor. The system is characterized in that it further comprises a scrubber for washing and cooling at least the first portion of the exhaust gas with a scrubber fluid. The scrubber is in communication with the ammonia engine to receive at least the first portion of the exhaust gas from the ammonia engine. Furthermore, the scrubber is in communication with the ammonia engine to supply the first portion of the exhaust gas to the ammonia engine after washing and cooling it.

An ammonia engine is understood to mean an engine which can be operated by at least ammonia and / or a fuel containing ammonia, but possibly also by other fuels.

When it is mentioned throughout the text that something is in communication with something else, then they can be in direct or indirect communication with each other.

The first portion can make up 0-100% of the exhaust gas, and this can vary over time. The first batch should typically represent 30-40% of the exhaust gas to enable compliance with applicable regulations

The second portion of the exhaust gas may or may not comprise the first portion of the exhaust gas. In the event that the second portion of the exhaust gas comprises the first portion of the exhaust gas, the scrubber may be arranged to receive, wash and cool the second portion of the exhaust gas.

The second portion of the exhaust gas may or may not exit the ammonia engine via the exhaust gas outlet.

By passing through the scrubber at least the first portion of the exhaust gas arranged to be recycled, it is effectively cooled sufficiently to be recycled. Further, it is rinsed with the scrubbing fluid, thereby purifying particulate matter and sulfur oxides if the fuel generating the exhaust gas should contain sulfur.

There are different types of scrubbers. One type of scrubber is the so-called open-loop scrubber, which uses seawater to wash and cool the exhaust gas. Seawater is then passed from the sea through the scrubber once to absorb pollutants and cool off the exhaust gas before discharging it back to the sea. Another type of scrubber is the so-called closed-loop scrubber, which uses circulating freshwater or seawater, optionally in combination with an alkaline agent such as sodium hydroxide (NaOH), sodium carbonate (Na2CO3) or magnesium oxide (MgO), to wash and cool the exhaust gas. In such a scrubber, the amounts of particulate matter and possibly salts in the fresh or circulating freshwater gradually increase. Thus, to control the quality of fresh or circulating seawater, a small amount thereof may occasionally or continuously be blown out to be cleaned before being recycled, stored on the ship or discharged overboard.

The system of production may be such that a scrubber fluid inlet of the scrubber is placed in communication with a scrubber fluid outlet of the scrubber. This allows a scrubbing fluid recirculation, i.e. in a closed loop scrubber. Closed loop scrubbers, especially closed loop freshwater scrubbers, may be particularly suitable for systems having an EGR function, since the scrubbing fluid will not contain seawater chlorides which could cause corrosion on components of the rest of the system.

The system may further comprise a circulation tank, which circulation tank is in communication with the scrubber, e.g. with the scrubber fluid outlet thereof, to receive the scrubber fluid from the scrubber after washing and cooling the first portion of the exhaust gas, and which circulation tank is in communication with the scrubber, e.g. with the scrubber fluid inlet thereof, to convey the scrubber fluid to the scrubber.

The system may further comprise a heat exchanger disposed downstream of the scrubber fluid outlet and upstream of the scrubber fluid inlet. Thereby, the scrubbing fluid can be cooled during recirculation, i.e. after passing through the scrubber and passing a second passage through the scrubber to allow sufficient cooling of the first portion of the exhaust gas. Various refrigerants of the heat exchanger are possible, e.g. seawater.

The system may further comprise a water purification unit. The water purifier may be placed in communication with the scrubber, optionally with the circulation tank, if present, to receive the scrubber fluid after washing and cooling the first portion of the exhaust gas and separating it into a first and second fraction. The second fraction is more polluted than the first fraction. The first fraction may be returned to the scrubber directly or indirectly, e.g. via the circulation tank, if present, or taken to a storage tank or discharged overboard which could necessitate replenishing scrubbing fluid. Thereby the scrubbing fluid in the system can be kept sufficiently clean for proper control of the scrubber.

The water purification unit may comprise a centrifugal separator such as a high speed separator, a decanter or combination thereof and / or a membrane filter.

According to one embodiment, the scrubber is located downstream of the turbine and the second portion of the exhaust gas comprises the first portion of the exhaust gas. Therefore, the second portion of the exhaust gas containing the first portion of the exhaust gas can be passed through the turbine, before at least the first portion of the exhaust gas is cleaned and cooled by the scrubber, and the first portion of the exhaust gas is recycled to the ammonia engine. This embodiment enables so-called low pressure EGR. An advantage of low pressure EGR is that existing wet scrubbers can be relatively easily modified so that they can be used in a low pressure EGR type system.

In the case of the above embodiment, a third portion of the exhaust gas, which is the second portion minus the first portion, can be discharged after passing the turbine, ie. without passing the scrubber. Alternatively, the scrubber may be arranged to receive and wash and cool with the scrubber fluid the second portion of the exhaust gas containing the first portion of the exhaust gas, i.e. also the third portion of the exhaust gas. Whether or not the third portion of the exhaust gas is passed through the scrubber, e.g. depend on the fuel used to drive the ammonia engine. For example, if a mixture of HFO and ammonia. used as fuel, the third portion of the exhaust gas can be passed through the scrubber. However, if a mixture of DO and ammonia is used as fuel, the third portion of the exhaust gas cannot be passed through the scrubber.

As an alternative to the above embodiment, the first portion of the exhaust gas may be separated from the second portion of the exhaust gas, and the scrubber may instead be placed upstream of the turbine after the first portion of the exhaust gas has been separated from the second portion of the exhaust gas. Therefore, only the second portion of the exhaust gas can be passed through the turbine, while only the first portion of the exhaust gas is cleaned and cooled by the scrubber and recycled to the ammonia engine. This embodiment enables so-called high pressure EGR. An advantage of high-pressure EGR is that particulate matter and sulfur oxides, if present in the exhaust gas, can be prevented from corroding or blocking some components of the system, which will be explained in more detail below.

The system may further comprise a fan, or EGR fan, arranged to draw the first portion of the exhaust gas through the scrubber and into the ammonia engine. With the aid of 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 placed in different positions in the system, e.g. on the fuel used to power the ammonia engine. For example, if the fuel is relatively dirty, the fan may be placed in front or upstream of the scrubber so that the exhaust gas is passed through the fan before being cooled in the scrubber. This allows deposits of particulate matter inside the fan to be minimized. On the one hand, if the fuel is relatively clean, the fan can be placed after or downstream of the scrubber so that the exhaust gas is passed through the fan after it is cooled in the scrubber. Such a downstream fan can handle a larger exhaust gas flow than an upstream fan, the passing exhaust gas being colder and thus less volume-demanding. Furthermore, such a downstream fan may be less "advanced" than an upstream fan as its components are exposed to lower temperatures.

One method of generating power on board a ship involves controlling an ammonia engine where an exhaust gas is produced, and recycling a first portion of the exhaust gas produced by the ammonia engine back to the ammonia engine. The method further 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 a turbine rotation to a compressor of the turbocharger to pressurize air, and supply of the pressurized air to the ammonia engine. . The process is characterized in that it further comprises supplying the first portion of the exhaust gas produced by the ammonia engine to a scrubber, washing and cooling with a scrubbing fluid of the first portion of the exhaust gas in the scrubber and after washing and cooling recirculation of the first portion. of the exhaust gas from the scrubber to the ammonia engine. Thus, the first portion of the exhaust gas is recirculated after being washed and cooled by the scrubber.

A scrubber fluid inlet of the scrubber may be placed in communication with a scrubber fluid outlet of the scrubber, and the method may further comprise recirculation of the scrubber fluid through the scrubber.

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

The method may further comprise supplying a portion of the scrubber fluid after it has been used for washing and cooling the first portion of the exhaust gas, from the scrubber to the water purifier and separation in the water purifier of the portion of the scrubber fluid into a first and second fraction, second fraction is more contaminated than first fraction.

The second portion of the exhaust gas produced by the ammonia engine may comprise the first portion of the exhaust gas produced by the ammonia engine. The method may further comprise supplying the second portion of the exhaust gas to the turbine prior to supplying the first portion of the exhaust gas to the scrubber. The total second portion of the exhaust gas, and not only the first portion, may or may not be received, washed and cooled by the scrubber.

Alternatively, the first portion of the exhaust gas produced by the ammonia engine may be separated from the second portion of the exhaust gas produced by the ammonia engine. The method may further comprise separating the first and second portions of the exhaust gas from one another before supplying the first portion to the scrubber and the second portion to the turbine.

The advantages outlined above for the various embodiments of the system according to the invention are also present for the correspondingly different embodiments of the method.

However, other objects, features, aspects and advantages of the invention will become apparent from the following detailed description as well as from the drawings.

Brief description of the drawings

The invention will now be described in more detail with reference to the accompanying schematic drawings, in which fig. 1 is a block diagram schematically illustrating a system for generating power on board a ship; FIG. 2 is a flowchart illustrating a method of generating power on board a ship by means of a system according to FIG. 1, FIG. 3 is a block diagram schematically illustrating an alternative system for generating power on board a ship; and

FIG. 4 is a flowchart illustrating a method for generating power on board a ship by means of a system according to FIG. Third

Detailed description

FIG. 1 illustrates a system 1 for generating power on board a ship (not illustrated). It includes an engine 3, a turbocharger 5, a scrubber 7, a circulation tank

9, a plate heat exchanger 11, a water purification unit 13 in the form of a high speed separator, a sludge tank 15, a chemical dosing unit 17, an EGR fan 18 and an air cooler 19. In contrast, the turbocharger 5 comprises a turbine 21 and a compressor 23, the engine 3 comprises an exhaust gas outlet. 25 and an exhaust gas inlet 27, and the scrubber 7 comprises a scrubber fluid inlet 29 and a scrubber fluid outlet 31. The scrubber 7 is based on either random or structured gasket, syringes, trays or a combination thereof. It works in a conventional way, which is not described further here.

FIG. 2 illustrates a method for generating power by the system 1. The motor 3 is driven by a mixture of HFO and ammonia, i. it is an ammonia engine and it generates exhaust gas EG (step A). As will be explained in more detail below, the system 1 is arranged to recycle a first portion EG1 of the exhaust gas EG to the engine 3 to reduce the nitric acid emissions. A second portion EG2 of the exhaust gas EG, which here is the entire exhaust gas and thus comprises the first portion EG1 of the exhaust gas, is fed from the engine 3 to the turbine 21 to rotate the same (step B). The rotation of the turbine 21 is used as force by the compressor 23 to pressurize and compress air taken from outside (step C). The pressurized compressed air is cooled by the air cooler 19 (step D) before being introduced into the engine 3 (step E). Once the exhaust gas has passed the turbine 21, it is fed through the EGR fan 18 to the scrubber 7 (step F). Inside the scrubber 7, the exhaust gas, which is still the entire exhaust gas, is washed and cooled with a scrubber fluid SF (Step G) in the form of fresh water containing an alkaline agent such as sodium hydroxide (NaOH). The scrubber fluid SF is fed from the circulation tank 9 via the heat exchanger 11 to the scrubber 7 through the scrubber fluid inlet 29 thereof. Inside the scrubber 17, the scrubber fluid SF cools the exhaust gas and absorbs pollutants from it to purify it, after which scrubber fluid SF is fed through scrubber fluid outlet 31 back to circulation tank 9. Therefore, scrubber fluid inlet 29 communicates indirectly, i. via the circulation tank 9 and the heat exchanger 11, with the scrubber fluid outlet 31, where the scrubber fluid SF is recycled through the scrubber 7 (step H). During the recirculation, the scrubber fluid SF is cooled by the heat exchanger 11 (step I) to allow sufficient cooling of the exhaust gas in the scrubber 7. Seawater is used as a cooling medium in the heat exchanger.

As scrubber fluid SF is recycled through scrubber 7, it becomes increasingly contaminated. To ensure effective operation of the scrubber 7, the scrubber fluid must not be too contaminated. Accordingly, a portion of the scrubbing fluid SF is continuously pumped from the circulation tank 9 to the water purification unit 13 (step J) to be purified. To ensure a sufficient amount of scrubbing fluid in the circulation tank 9, it may be necessary to replenish it with scrubber fluid to replace the scrubber fluid pumped away. As the scrubber fluid cools the exhaust gas, the water vapor in the exhaust gas can condense, which can result in an automatic, continuous replenishment of the scrubber fluid and, optionally, an excess amount of scrubber fluid, which necessitates the discharge of scrubber fluid into the water purifier unit. system 1. In addition, an "internal" replenishment of scrubber fluid may occur when the scrubber fluid returns to circulation tank 9 after purification, which will be explained in more detail below.

The water purification unit 13 separates the portion of the scrubber fluid SF into a first and second fraction (step K). The second fraction, which is more contaminated than the first fraction, is fed to sludge tank 15 (step L). The first fraction is returned to circulation tank 9, which results in an "internal" replenishment of scrubber fluid, or to a storage tank (not illustrated) or discharged (step M).

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

After the purified and cooled exhaust gas leaves the scrubber 7, the first portion EG1 thereof is fed to compressor 23 to be pressurized and compressed (step O) before being fed to cooler 19 to be cooled (step P). Furthermore, the first portion EG1 of the exhaust gas is returned or recirculated to the engine 3 (step Q). Thus, the exhaust gas outlet 25 communicates indirectly, viz. via the turbine 21, scrubber 7, compressor 23 and cooler 19, with exhaust gas inlet 27 to allow exhaust gas recirculation. The compression, cooling and supply to the engine of the first portion EG1 of the exhaust gas (stages O, P and Q) on the one hand and the air taken from outside (stages C, D and E) on the other side are carried out simultaneously, i.e. on the mixture of the outdoor air and the first portion of the exhaust gas. At the same time, a third portion of EG3 of the exhaust gas, which is the second portion of EG2 minus the first portion of EG1 of the exhaust gas, is discharged from system 1 (step R).

In the above system 1, the second portion EG2 of the exhaust gas is the entire exhaust gas, ie. the second portion EG2 of the exhaust gas comprises the first portion EG1 of the exhaust gas. The entire exhaust gas is thus used to rotate the turbine 21, and the entire exhaust gas is purified and cooled by the scrubber 7. After the scrubber 7, the second portion EG2 is divided, ie. the entire exhaust gas, in the first and third portions of EG1 and EG3. The first portion EG1 is recirculated to the engine 3, while the third portion EG3 is discharged from the system 1. The system 1 is thus of a so-called low pressure type. A disadvantage of low-pressure systems may be that the first portion of EG1 of the exhaust gas, and in particular the pollutants contained therein, is passed through the cooler 19, which can result in corrosion and deposits in the cooler.

According to an alternative embodiment, the scrubber 7 can be placed to cool and wash only the first portion of EG1 of the exhaust gas, especially if the ammonia engine 3 is driven by a cleaner fuel such as pure ammonia or a mixture of ammonia and DO. The second portion of EG2, i.e. the entire exhaust gas can then be divided into the first and third portions of EG1 and EG3 after the turbine 21 but before the scrubber 7, after which the third portion EG3 can be discharged from the system.

FIG. 3 illustrates another system 51 for generating power on board a ship (not illustrated). It comprises an engine 3, a turbocharger 5, a scrubber 7, a circulation tank 9, a plate heat exchanger 11, a water purification unit 13 in the form of a high-speed separator, a slurry tank 15, a chemical dosing unit 17 and an air cooler 19. In contrast, the turbocharger 5 comprises a turbine 21 and a compressor 23, the engine 3 comprises an exhaust gas outlet 25 and an exhaust gas inlet 27, and the scrubber 7 comprises a scrubber fluid inlet 29 and a scrubber fluid outlet 31. Like the aforementioned scrubber, this scrubber 7 is based on either random or structured gasket, syringe, or a combination thereof. It works in a conventional way, which is not described further here. FIG. 4 illustrates a method for generating power by the system 51. The motor 3 is driven by a mixture of HFO and ammonia, i. it is an ammonia engine and it generates exhaust gas EG (step A). As will be explained in more detail below, the system 51 is arranged to recycle a first portion EG1 of the exhaust gas EG to the engine 3 to reduce the nitric acid emissions. Downstream of the engine 3, the exhaust gas EG is divided into the first portion EG1 and a second portion EG2 of the exhaust gas. Here, the first and second portions of EG1 and EG2 are thus separate portions of the exhaust gas EG. The second portion EG2 of the exhaust gas EG is fed from the engine 3 to the turbine 21 to rotate the same (step B). The rotation of the turbine 21 is used as force by the compressor 23 to pressurize and compress air taken from outside (step C). The pressurized compressed air is cooled by the air cooler 19 (step D) before being introduced into the engine 3 (step E). The first portion EG1 of the exhaust gas EG is fed to scrubber 7 (step F). Inside scrubber 7, the first portion of EG1 is washed and cooled by the exhaust gas with a scrubber fluid SF (Step G) in the form of fresh water containing an alkaline agent such as sodium hydroxide (NaOH). The scrubber fluid SF is fed from the circulation tank 9 via the heat exchanger 11 to the scrubber 7 through the scrubber fluid inlet 29 thereof. Inside the scrubber 17, the scrubber fluid SF cools the exhaust gas and absorbs pollutants from it to purify it, after which the scrubber fluid SF is fed through the scrubber fluid outlet 31 back to the circulation tank 9. Therefore, the scrubber fluid inlet 29 communicates indirectly, i. via the circulation tank 9 and the heat exchanger 11, with the scrubber fluid outlet 31, where the scrubber fluid SF is recycled through the scrubber 7 (step H). During recirculation, the scrubber fluid SF is cooled by the heat exchanger 11 (step I) to allow sufficient cooling of the exhaust gas in the scrubber 7.

As scrubber fluid SF is recycled through scrubber 7, it becomes increasingly contaminated. To ensure effective operation of the scrubber 7, the scrubber fluid must not be too contaminated. Accordingly, a portion of the scrubbing fluid SF is continuously pumped from the circulation tank 9 to the water purification unit 13 (step J) to be purified. To ensure a sufficient amount of scrubbing fluid in the circulation tank 9, it may be necessary to fill it with scrubber fluid to replace the scrubber fluid pumped away. As the scrubber fluid cools the exhaust gas, the water vapor in the exhaust gas can condense, which can result in an automatic, continuous replenishment of the scrubber fluid and, optionally, an excess amount of scrubber fluid, which necessitates the discharge of scrubber fluid into the water purifier unit. system 1. In addition, an "internal" replenishment of scrubber fluid may occur when the scrubber fluid returns to circulation tank 9 after purification, which will be explained in more detail below.

The water purification unit 13 separates the portion of the scrubber fluid SF into a first and second fraction (step K). The second fraction, which is more contaminated than the first fraction, is fed to sludge tank 15 (step L). The first fraction is returned to circulation tank 9, which results in an "internal" replenishment of scrubber fluid, or to a storage tank (not illustrated) or discharged (step M).

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

After the cleaned and cooled first portion of EG1 of the exhaust gas leaves the scrubber 7, it is returned or recycled to the engine 3 (step Q). Thus, the exhaust gas outlet 25 communicates indirectly, viz. via the scrubber 7, with the exhaust gas inlet 27 to allow exhaust gas recirculation. The supply to the engine of the first portion EG1 of the exhaust gas (stage Q) on the one hand and the cooled pressurized air taken from outside (stage E) on the other side is carried out simultaneously in a single function, ie. on the mixture of the outdoor air and the first portion of the exhaust gas. When the second portion of EG2 of the exhaust gas has passed the turbine 21, it is discharged from the system 51 (step R).

In the above system 51, the second portion EG2 of the exhaust gas does not include the first portion EG1 of the exhaust gas. Thus, only the second portion EG2 of the exhaust gas is used to rotate the turbine 21 before it is discharged from the system 57. Furthermore, only the first portion EG1 of the exhaust gas is purified and cooled by the scrubber 7 before being recycled to the engine. 3. The system 51 is thus of a so-called high pressure type. An advantage of this system is that the first portion of EG1 of the exhaust gas EG, and in particular the pollutants contained therein, does not pass through the cooler 19, which may reduce the risk of corrosion and blocking of the cooler.

According to an alternate embodiment, the system 57 may comprise another scrubber disposed downstream of the turbine 21 to clean the second portion of EG2 of the exhaust gas before discharging. Such additional scrubber may be accompanied by a separate circulation tank, heat exchanger, chemical dosing unit, water purification unit and sludge tank, or it could share one or more of these components with the scrubber 7.

In both of the systems described above, the scrubber not only removes pollutants from the exhaust gas to make it less harmful to the environment, but it also effectively cools the exhaust gas to allow a recycle thereof. The exhaust gas recirculation reduces the oxygen concentration of the engine's combustion air, which in turn will reduce the formation of nitric acid in the exhaust gas.

The components of the systems described above are connected by suitable pipelines to enable them to communicate in the manner specified above and to enable the above specified flows between the components. The pipeline shape can vary between different embodiments of the generation. For example, in embodiments of the system which are alternatives to that illustrated in FIG. 1, the air and the first portion of the exhaust gas are passed from the compressor to the engine through various and not common pipelines. The first fraction of the scrubbing fluid can also be passed from the water purification unit to the circulation tank through separate pipelines. Likewise, the first and third portions of EG1 and EG3 of the exhaust gas can leave the scrubber through separate pipelines. As another example, the air and the first portion of the exhaust gas in embodiments of the system which are alternatives to the one illustrated in FIG. 3, respectively. the cooler and scrubber for the engine through various pipelines throughout. The first and second portions of EG1 and EG2 of the exhaust gas can also leave the engine through separate pipelines.

The above-described embodiment of the present invention is to be considered by way of example only. One skilled in the art recognizes that the embodiment disclosed can be varied in a number of ways without departing from the inventive concept.

In the above described embodiments, the first fraction of the scrubber fluid is fed from the water purification unit to the circulation tank, discharged overboard or fed to a storage tank. The first fraction can be further purified, e.g. by means of a membrane before it is fed to a circulation tank or storage tank or discharged overboard. Whether the first fraction is fed to the circulation tank, to a storage tank or overboard may depend on its quality, the ship's environment and the amount of scrubbing fluid. Furthermore, the scrubbing fluid does not need to be continuously transferred from the circulation tank to the water purification unit. The supply may be discontinuous. It can also vary over time.

The systems described above may include additional components to function properly, such as pumps, valves, sensors, water analysis units, controllers, etc. As an example, the systems may include a pH meter or sensor between the scrubber and the circulation tank for measuring the scrubber fluid. pH. This pH meter can communicate with the chemical dosing unit 17. As another example, the systems may comprise an EGR valve for controlling the flow of recycled exhaust gas.

Alternative positioning of the system components relative to each other is possible. The chemical dosage unit may e.g. placed 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, e.g. if the ammonia engine is powered by cleaner fuel such as pure ammonia or a mixture of DO and ammonia. Furthermore, if the ammonia engine is powered by cleaner fuel, the EGR fan can be placed after or downstream of the scrubber.

The chemical provided by the chemical dosing unit may contain other / additional chemicals than the alkaline agent such as a flocculant and / or a coagulant. In addition, the water purification may further comprise a flocculating unit disposed upstream, i.e. in front of the high-speed separator and downstream, ie. after the chemical dosing unit. Such a flocculating unit may be arranged to hold the scrubber fluid before it is received by the high-speed separator to allow sufficient time for flocculation. This can optimize the efficiency of the high-speed separator.

A system according to the invention need not include a circulation tank. Thus, in an alternative embodiment, the water purification unit may be arranged to feed the first fraction to the scrubber instead of to a circulation tank. In another alternative embodiment, the system may be of an open loop type so that it does not include recirculation or return of the scrubber fluid.

The scrubbing fluid need not include fresh water and an alkaline agent, but may instead comprise seawater and an alkaline agent or a combination thereof. However, use of seawater in the scrubbing fluid may require the use of certain materials for the system components to avoid corrosion problems.

It should be emphasized that the steps of the process of the production have been called step A, step B, etc. solely for the purpose of identification. Thus, the steps need not be performed in the specific order of steps A, step B, etc. Furthermore, one or more steps can be omitted in alternative embodiments.

It should be emphasized that the first, second, third, etc. attributes are used herein solely to distinguish between purposes and not to express a particular specific order.

It should be emphasized that a description of details not relevant to the present invention has been omitted and that the figures are purely schematic and not drawn to scale.

Claims (9)

A system (1, 51) for generating power on board a ship, comprising an ammonia engine (3) disposed to produce an exhaust gas, and a turbocharger (5) containing a turbine (21) and a compressor (23) ), wherein the ammonia engine (3) contains an exhaust gas outlet (25) and an exhaust gas inlet (27) connected to allow recirculation of a first portion (EG1) of the exhaust gas (EG) produced by the ammonia engine (3). the ammonia engine (3), wherein the turbine (21) is in communication with the ammonia engine (3) and arranged to be rotated by a second portion (EG2) of the exhaust gas (EG) produced by the ammonia engine (3), wherein the compressor ( 23) is arranged to be driven by turbine rotation to pressurize air, and wherein the compressor (23) is in communication with the ammonia motor (3) to supply the pressurized air to the ammonia motor (3), further characterized by a scrubber (7) for washing and k ejecting the first portion (EG1) of the exhaust gas (EG) with a scrubber fluid (SF), said scrubber (7) communicating with the ammonia engine (3) to receive the first portion (EG1) of the exhaust gas (EG) from the ammonia engine ( 3) and which scrubber (7) is in communication with the ammonia engine (3) to supply the first portion (EG1) of the exhaust gas (EG) to the ammonia engine (3) after purification and cooling thereof. The system (1, 51) of claim 1, wherein a scrubber fluid inlet (29) of the scrubber (7) is arranged in communication with a scrubber fluid outlet (31) of the scrubber (7). The system (1, 51) of claim 2, further comprising a circulation tank (9), wherein the circulation tank (9) is in communication with the scrubber (7) to receive the scrubber fluid (SF) from the scrubber (7) after washing and cooling. and the circulation tank (9) is in communication with the scrubber (7) to supply the scrubber fluid (SF) to the scrubber (7). A system (1, 51) according to any of claims 2-3, further comprising a heat exchanger (11) disposed downstream of the scrubber fluid outlet (31) and upstream of the scrubber fluid inlet (29). A system (1, 51) according to any one of the preceding claims, further comprising a water purification unit (13) arranged in communication with the scrubber (7) to receive the scrubber fluid (SF) after washing and cooling and separating the that in a first and a second fraction, which second fraction is more contaminated than the first fraction. System (1) according to any one of the preceding claims, wherein the scrubber ( 7) is disposed downstream of the turbine (21) and the second portion (EG2) of the exhaust gas (EG) comprises the first portion (EG1) of the exhaust gas (EG). System (1) according to claim 6, wherein the scrubber (7) is arranged to receive and wash and cool with the scrubber fluid (SF) the second portion (EG2) of the exhaust gas (EG). System (51) according to any one of claims 1-5, wherein the scrubber (7) is arranged upstream of the turbine (21) and the first portion (EG1) of the exhaust gas 10 (EG) is separated from the second portion (EG2) of the exhaust gas (EG). System (1, 51) according to any one of the preceding claims, further comprising a fan (18) arranged to draw the first portion (EG1) of the exhaust gas (EG) through the scrubber (7) and into in the ammonia engine (3).