KR20220159900A - A large two-stroke uniflow scavenged turbocharged internal combustion engine with an ammonia absorption system - Google Patents

Abstract

The present invention relates to a large two-stroke uniflow scavenged turbocharged internal combustion engine having at least one operating mode in which ammonia is used as main fuel. The engine includes: at least one cylinder having a cylinder liner (1), a reciprocating piston (10) in the cylinder liner, and a cylinder cover (22) covering the cylinder; a combustion chamber (15) formed between the reciprocating piston (10) and the cylinder cover (22) in the cylinder (10); an ammonia fuel system (30) configured to supply pressurized ammonia to a fuel valve (50, 50') located in the cylinder cover (22) or the cylinder liner (1); and ammonia evacuation flow paths (42, 44, 47) connecting an outlet of the ammonia fuel system (30) to an inlet of an ammonia absorption system (60). The ammonia absorption system (60) contains water during use for absorbing ammonia supplied through the ammonia evacuation flow paths. The present invention improves the safety of ships and personnel.

Description

A LARGE TWO-STROKE UNIFLOW SCAVENGED TURBOCHARGED INTERNAL COMBUSTION ENGINE WITH AN AMMONIA ABSORPTION SYSTEM}

The present invention relates to a large two-stroke uniflow scavenging turbocharged internal combustion engine in at least one mode of operation in which ammonia is the fuel for combustion in the engine.

Large two-stroke single-flow scavenging turbocharged compression ignition internal combustion crosshead engines are commonly used as propulsion systems for large ships or as prime movers for power plants. These engines are completely different from ordinary combustion engines in their enormous size, weight and power output, and large two-stroke turbocharged compression internal combustion engines are themselves classified as a class.

BACKGROUND OF THE INVENTION Internal combustion engines have in the past mainly operated on hydrocarbon fuels such as fuel oil such as diesel oil or fuel gas such as natural gas or petroleum gas. Combustion of hydrocarbon fuels releases carbon dioxide (CO2) as well as other greenhouse gases that contribute to air pollution and climate change. Unlike fossil fuel impurities, which emit by-products, CO2 is an unavoidable consequence of hydrocarbon combustion. The energy density and CO2 footprint of a fuel depend on the hydrocarbon chain length and the complexity of the hydrocarbon molecules. Thus, gaseous hydrocarbon fuels have lower emissions than liquid hydrocarbon fuels, but gaseous hydrocarbon fuels have the disadvantage of being more difficult and expensive to handle and store. Research on non-hydrocarbon fuels is being conducted to reduce CO2 emissions.

Ammonia is a compound obtained from fossil fuels, biomass or renewable energy sources (wind, solar, hydro or thermal) and when produced from renewable energy sources, ammonia produces little or no carbon emission, or when burned produces CO2, SOx, or particulate matter. or almost no unburned hydrocarbons.

Ammonia has been tested and used on a small scale in small spark-ignition internal combustion engines, but has not been used to power compression-ignition internal combustion engines.

Ammonia has a dangerous and pungent odor. Therefore, it is necessary to avoid ammonia escaping from the engine. When ammonia operation is stopped and changed to, for example, conventional fuel operation, the fuel system must be purged of ammonia, and the ammonia that has been purged cannot simply be vented to the atmosphere/ambient . Other scenarios in which excess ammonia must be dealt with may arise, for example, due to engine leaks or other malfunctions. In these and similar scenarios, there is a need to provide a solution to the end of ammonia.

CN112696289 discloses a marine liquid ammonia fueling and fuel recycling system. The system consists of an ammonia fuel engine, a liquid ammonia supply system, a liquid ammonia recycling system and a liquid ammonia nitrogen purge ventilation system. According to this system, high-pressure liquid supply (70 bar, 45+/-10°C) of liquid ammonia fuel for ships is realized, and a large amount of fuel can be saved because the liquid ammonia fuel that is not consumed in the pipeline can be recycled. Meanwhile, it improves the safety of the vessel and personnel by reducing the ammonia fuel discharged to the ventilation mast.

It is an object of the present invention to provide a large two-stroke single-flow scavenging turbocharged internal combustion engine that overcomes or at least reduces the aforementioned problems.

The foregoing and other objects are achieved by the features of the independent claims. Further implementation forms are apparent from the dependent claims, detailed description and drawings.

According to a first aspect, there is provided a large two-stroke single-flow scavenging turbocharged internal combustion engine having at least one mode of operation in which the primary fuel is ammonia, the engine comprising:

- at least one cylinder having a cylinder liner and a reciprocating piston therein and a cylinder cover covering the cylinder;

- a combustion chamber formed inside the cylinder between the reciprocating piston and the cylinder cover;

- an ammonia fuel system configured to supply pressurized ammonia to a fuel valve disposed on a cylinder cover or cylinder liner;

- ammonia absorption system 60 and

- an ammonia flow path connecting the outlet of the ammonia fuel system to the inlet of the ammonia absorption system;

The ammonia intake system contains water in use to form ammonia water by absorbing ammonia supplied into the water through the discharge passage.

By providing a purge passage and an ammonia absorption system, it becomes possible to deal with a sudden event in which the engine needs to deal with an excess of ammonia, such as a purge event or a leak event required when the operation by ammonia fuel is terminated. By dissolving ammonia in the water-containing absorption system, it is possible to temporarily store a significant amount of ammonia in water to produce ammonia water. Ammonia water can be used as a fuel in engines or as a reducing agent in SCR (Selective Catalyst Reduction) reactors to clean exhaust gases.

The inventors have found that the solubility of ammonia generally increases as the water temperature decreases. Adding a cooling circuit facility to cool the water has the potential to increase the actual amount of ammonia recovered in the recovery system (tank) to a higher recovery rate.

In a possible implementation of the first aspect, the ammonia absorption system comprises at least one vessel at least partially filled with water during use, the at least one vessel preferably comprising a water inlet for connection to a water source, preferably includes an ammonia water outlet for discharging ammonia water.

In a possible implementation of the first aspect, the engine is a dual fuel engine and preferably includes a fuel system for supplying conventional fuel to the cylinders of the engine.

In a possible implementation of the first aspect, the ammonia water outlet is connected to an ammonia fuel system for burning ammonia water in an engine.

In a possible implementation of the first aspect, the engine includes an SCR reactor in an exhaust gas flow path of the engine, and an ammonia water outlet is connected to a reducing agent inlet associated with the SCR reactor.

In a possible implementation of the first aspect, the ammonia absorption system comprises a pressure vessel at least partially filled with water during use, preferably the pressure vessel is provided with a cooling system for lowering the temperature of the pressure vessel, the pressure vessel preferably It preferably includes a gaseous ammonia inlet for inhaling gaseous ammonia, and the pressure vessel is preferably connected to a water supply source, and the pressure vessel preferably has an ammonia water outlet for discharging the ammonia water.

In a possible implementation of the first aspect, the ammonia absorption system comprises a packed absorption tower, the packed absorption tower preferably comprising a gaseous ammonia inlet for taking in gaseous ammonia, the packed absorption tower preferably The packed absorption tower connected to the water source preferably has an ammonia water outlet for discharge of the ammonia water.

In a possible implementation of the first aspect, the ammonia absorption system comprises a first step comprising a cascade water tank at least partially filled with water during use, preferably a gaseous ammonia inlet and a gaseous ammonia outlet, a water inlet and an ammonia water outlet. cistern,

A subsequent water tank preferably comprising a gaseous ammonia inlet connected to the gaseous ammonia outlet of the first water tank and an ammonia water outlet connected to the water inlet of the first water tank and the ammonia vapor outlet, the cascade water tank preferably It is configured for the countercurrent flow of the water flow to the flow of gaseous ammonia, and the tank most upstream from the flow of gaseous ammonia in use has the highest ammonia concentration in the water in the tank and is provided with an ammonia water outlet, the most upstream of the flow of gaseous ammonia in use. The downstream tank has the lowest ammonia concentration in the water in the tank, and the tank most downstream in the flow of gaseous ammonia is preferably provided with an outlet for discharging the gaseous material from the tank.

In a possible implementation of the first aspect, the ammonia fuel system includes a purge system configured to evacuate ammonia from the fuel system to the ammonia absorption system, the purge system preferably including a pressurized nitrogen source, the pressurized nitrogen source preferably is connected to the fuel system through a purge valve, and the purge system preferably uses an ammonia discharge passage to purge ammonia from the ammonia fuel system to the ammonia absorption system.

In a possible implementation of the first aspect, the ammonia fuel system comprises an intermediate pressure ammonia supply line and an ammonia return line, a first purge line connecting the intermediate pressure ammonia supply line to the ammonia absorption system, and a second purge line connecting the ammonia return line to the ammonia absorption system. A purge line and preferably a valve arrangement for selectively connecting the medium pressure ammonia supply line and the ammonia return line to the ammonia absorption system.

In a possible implementation form of the first aspect, a knockout drum is disposed in the first and/or second purge line, the knockout drum is configured to separate liquid ammonia from gaseous ammonia, and the knockout drum comprises a gaseous ammonia outlet and a liquid ammonia outlet. wherein the gaseous ammonia outlet of the knockout drum is connected to an ammonia absorption system, and the liquid ammonia outlet is preferably connected to a recovery tank, which in turn is connected to an ammonia fuel system.

In a possible implementation form of the first aspect, the ammonia fuel system includes a supply line and a return line, the piping forming the supply line and the return line includes a double-walled piping, and a space between an inner tube of the double-walled piping and an outer tube of the double-walled piping. is fluidly connected to the ammonia absorption system by means of an ammonia discharge passage.

In a possible implementation form of the first aspect, the ammonia fuel system includes a liquid ammonia fuel tank, a low pressure ammonia supply line connecting the liquid ammonia fuel tank to an inlet of a medium pressure fuel pump by action of a low pressure pump, and the fuel system preferably comprises: includes a medium-pressure fuel line connecting the outlet of the medium-pressure pump to the inlet of the fuel valve;

The fuel system preferably includes a return line connecting the outlet of the fuel valve to the inlet of the medium pressure fuel pump.

In a possible implementation of the first aspect, at least one cylinder is provided with a scavenging port in a lower region of the cylinder.

In a possible implementation form of the first aspect, the cylinder cover is provided with a central exhaust valve, and two or more fuel valves surround the central exhaust valve.

According to a second aspect, a method for managing ammonia in a large two-stroke single-flow scavenging turbocharged internal combustion engine having at least one mode of operation in which the primary fuel is ammonia is provided, the engine comprising:

- at least one cylinder having a cylinder liner and a reciprocating piston therein and a cylinder cover covering the cylinder;

- a combustion chamber formed inside the cylinder between the reciprocating piston and the cylinder cover;

- an ammonia fuel system configured to supply pressurized ammonia to a fuel valve disposed in a cylinder cover or cylinder liner;

The method,

- conveying excess gaseous ammonia from the fuel system to the ammonia absorption system and absorbing gaseous ammonia from water to form aqueous ammonia.

In a possible implementation of the second aspect, the method further comprises separating liquid and gaseous ammonia from excess ammonia, preferably using a knockout drum, conveying the gaseous ammonia to an ammonia absorption system and adding ammonia to water. and absorbing to form ammonia water.

In a possible implementation of the second aspect, the method includes forming aqueous ammonia as fuel for the engine or as a reducing agent for the SCR reactor of the engine.

In a possible implementation of the second aspect, the method includes using ammonia water as a fuel for the engine or as a reducing agent for the SCR reactor of the engine.

These and other aspects of the invention will be apparent from the following examples.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following detailed descriptions of the disclosure, aspects, embodiments and implementations of the present invention, a more detailed explanation is given with reference to exemplary embodiments shown in the drawings.
1 is an elevated front view of a large two-stroke diesel engine according to an exemplary embodiment.
Figure 2 is an elevated side view of the large two-stroke engine of Figure 1;
3 is a schematic diagram of a large two-stroke engine according to FIG. 1;
4 is a schematic diagram of an engine with an ammonia fuel system, an ammonia purge system and an ammonia absorption system according to the first embodiment.
5 is a schematic diagram of an engine with an ammonia fuel system, an ammonia purge system and an ammonia absorption system according to a second embodiment.

In the detailed description that follows, the compression ignition internal combustion engine will be described with reference to a large two-stroke low speed single flow scavenging turbocharged compression ignition internal combustion engine including a crosshead in exemplary embodiments, but the compression ignition internal combustion engine may be different. It is understood that there is Large two-stroke low-speed single-flow scavenging turbocharged internal combustion engines may be of the (high pressure) type in which the fuel is injected at or near the top dead center of the piston where compression is ignited, or the scavenging and fuel are mixed (low pressure) before or during compression where spark ignition occurs. can In the latter case there will usually be a "pilot" ignition using an ignition fluid such as fuel oil to ensure reliable ignition.

1 , 2 and 3 show a large slow speed turbocharged two stroke compression ignition engine with crankshaft 8 and crosshead 9 . Figure 3 shows a schematic diagram of a large slow speed turbocharged two-stroke diesel engine with intake and exhaust systems. In this exemplary embodiment, the engine has six cylinders in a row. Large slow speed turbocharged two-stroke diesel engines typically have from 4 to 14 cylinders in rows, supported by a cylinder frame 23 supported by an engine frame 11. This engine can be used, for example, as a stationary engine operating a main engine of a ship or a generator of a power plant. The total output of this engine may be, for example, 1,000 to 110,000k.

This engine, in this exemplary embodiment, is dual fuel compression of a two-stroke single-flow type equipped with a scavenging port 18 in the lower region of each cylinder liner 1 and a central exhaust valve 4 at the top of the cylinder liner 1. It is an ignition engine. The engine has at least one ammonia mode in which the engine is operated with ammonia fuel or ammonia-based fuel and at least one conventional fuel mode in which the engine is operated with conventional fuel such as fuel oil (marine diesel oil) or heavy oil.

The scavenging air passes from the scavenging air receptacle 2 to the scavenging port 18 of the individual cylinder 1 . The piston 10 reciprocating between the bottom dead center (BDC) and the top dead center (TDC) within the cylinder liner 1 compresses the scavenged air. Fuel (ammonia in ammonia mode) is injected into the combustion chamber of the cylinder liner 1 at or near TDC through a (high pressure) fuel valve 50 disposed on the cylinder cover 22 . Combustion then proceeds and exhaust gases are produced. Each cylinder cover 22 is provided with two or more fuel valves 50 . Fuel valve 50 is only configured to inject one particular type of fuel, eg ammonia, in which case there will also be two or more fuel valves 54 injecting existing fuel into the combustion chamber. So your engine will have four or more fuel valves. There may be more than one fuel valve 50 for each cylinder, provided that the fuel valve 50 is suitable for injecting all of the ammonia suitable for injecting conventional fuel. A fuel valve 50 is disposed on the cylinder cover 22 around the central exhaust valve 4 . In addition, an additional fuel valve (not shown), usually smaller, is provided in the cylinder cover to inject an ignition fluid to ensure reliable ignition of the ammonia fuel. The ignition fuel is, for example, dimethyl ether (DME) or fuel oil, but may also be another type of ignition enhancer, such as hydrogen. Since the engine may be a dual fuel engine, a conventional fuel supply system (not shown) may also be provided to supply conventional fuel to the fuel valve 50 . In one embodiment, the fuel valve 50' is disposed along the cylinder liner (shown in dotted lines) and directs fuel into the cylinder liner before the piston 10 passes through the fuel valve 50' en route from BDC to TDC. Accept. Thus, the piston 10 compresses the mixture of scavenge air and fuel. Timed ignition at or near TDC is triggered by sparks, lasers, or jets of ignition fluid. In the embodiment with the fuel valve 50', the pressure at which the fuel is received is significantly lower than the pressure at which the fuel is injected in the embodiment with the fuel valve 50 in the cylinder cover 22. Thus, the pressure at which fuel supply system 30 must deliver fuel can be significantly lower and/or pressure boosters often used with fuel valves 50 located in cylinder covers can be avoided.

When the exhaust valve 4 is opened, the exhaust gas flows to the exhaust gas receiver 3 through the exhaust duct coupled with the cylinder, and continues through the SCR (Selective Catalytic Reduction) reactor to the first exhaust duct ( After flowing through 19) to the turbine 6 of the turbocharger 5, this exhaust gas is discharged to the outlet 21 and the atmosphere via the economizer 20 through the second exhaust duct. SCR reactors reduce emissions, especially NOx emissions.

The turbine 6 drives a compressor 7 which is supplied with fresh air via an air inlet 12 via a shaft. The compressor 7 delivers pressurized scavenging air to the scavenging conduit 13 leading to the scavenging air receiver 2 . The scavenging air in this scavenging conduit 13 passes through the intercooler 14 for scavenging cooling.

If the compressor 7 of the turbocharger 5 does not deliver sufficient pressure to the scavenging air receiver 2, i.e. under low load or part load conditions of the engine, the cooled scavenge air pressurizes the scavenging flow into the electric motor 17. ) Passes via the auxiliary blower 16 driven by. At higher engine loads, after the turbocharger compressor (7) delivers sufficiently pressurized scavenging air, the auxiliary blower (16) is bypassed via the non-return valve (15) and the electric motor (17) is deactivated.

The engine is in an ammonia mode operating with ammonia as the primary fuel supplied to the ammonia valve 50 at a substantially stable pressure and temperature. Ammonia may be supplied to the ammonia valve 50 in a liquid or gaseous state. The ammonia liquid phase may be aqueous ammonia (ammonia-water mixture).

Existing fuel systems are well known and are not shown and described in more detail. The ammonia fuel system 30 supplies liquid ammonia to the fuel valve 50 at an intermediate supply pressure (eg, 30 to 80 bar pressure). Alternatively, the ammonia fuel is supplied to the ammonia valve 50 at a relatively low supply pressure (eg, 30 to 80 bar pressure) in the gas phase. In the case of a compression ignition type engine, the fuel valve 50 includes a pressure booster that greatly increases the pressure of the ammonia fuel from medium pressure to high pressure so that the ammonia fuel is injected at a pressure much higher than the compression pressure of the engine. In general, the injection pressure of an ignition-compression type engine exceeds 300 bar.

Referring to FIG. 4 , an ammonia fuel system 30 comprising a purge and ammonia absorption system 60 is disclosed in more detail. Ammonia is stored as a liquid in a pressurized storage tank 31 at approximately 17 bar. Ammonia can be stored as a liquid in an ammonia storage tank (31) at a pressure in excess of 8.6 bar and an ambient temperature of 20°C. However, the ammonia is preferably stored above about 17 bar to remain liquid when the ambient temperature rises.

A low pressure ammonia supply line 32 connects the outlet of the ammonia storage tank 31 to the inlet of the medium pressure feed pump 35. The low-pressure feed pump 33 forcibly supplies liquid ammonia from the tank 31 through the filter device 34 to the inlet of the medium-pressure feed pump 35. The medium pressure feed pump 35 forcibly supplies liquid ammonia to the fuel valve 50 through the medium pressure ammonia supply line 36. A portion of the liquid ammonia supplied to the fuel valve 50 is injected into the combustion chamber of the engine while another portion of the liquid ammonia supplied to the fuel valve 50 connects the return port of the fuel valve 50 to the low pressure supply line 32. It is returned to the connecting ammonia return line (38). Accordingly, a portion of the liquid ammonia fuel is recycled to the inlet of the medium pressure feed pump 35.

When operation on ammonia fuel is discontinued, for example, due to failure of the ammonia fuel system 30 or other reason for switching to conventional fuel, the ammonia fuel system 30 is purged to remove ammonia from the system. Here, a pressurized nitrogen source 40, for example a pressurized nitrogen container 40, is connected via a purge valve 41 to a medium-pressure ammonia supply line 36, preferably immediately downstream of the medium-pressure feed pump 35.

A first purge line 42 comprising a second purge valve 43 connects the medium pressure ammonia supply line 36 to the knockout drum 46 . A second purge line (44) comprising a third purge valve (45) connects the ammonia return line (38) to the knockout drum (46). In the purge operation, the first, second and third purge valves 41, 43 and 45 are opened and pressurized nitrogen drives residual ammonia fuel from the ammonia fuel supply and return lines 36 and 38 into the knockout drum 46. The knockout drum 46 is configured to separate liquid ammonia fuel from gaseous ammonia. A nitrogen vent line 48 including a nitrogen vent valve 49 connects the interior of the knockout drum 46 to the ambient environment to evacuate nitrogen from the knockout drum 46 . The liquid ammonia outlet is located in the lower region of the knockout drum 46 and is connected to the recovery tank 57. Liquid ammonia in recovery tank 57 is conveyed to ammonia storage tank 31 for use as ammonia fuel in one embodiment. The vapor phase ammonia outlet of the knockout drum 46 is connected to the ammonia absorption system 60 via a third purge line 47.

The ammonia absorption system 60 includes at least one vessel that is at least partially filled with water for absorbing ammonia into the water to form aqueous ammonia during use. Ammonia water, also called aqueous ammonia, is a solution of ammonia dissolved in water.

This embodiment includes a pressure vessel 58 that is at least partially filled with water during use. Pressure vessel 58 is preferably cooled (cooling means not shown) because dissolving ammonia in water generates heat and the ability of water to absorb ammonia decreases as the temperature of the water increases. Accordingly, the cooling means is configured to keep the temperature of the water in the pressure vessel 58 reduced in order to optimize the capacity of the water in the pressure vessel 58 to absorb ammonia.

The pressure vessel 58 has a gaseous ammonia inlet for receiving gaseous ammonia through a pressure vessel ammonia supply conduit 59. The pressure vessel ammonia supply conduit 59 includes a non-return valve 73 to prevent back flow of fluid from the pressure vessel 58 to the third purge line 47. The pressure vessel 58 has an inlet for (fresh water) water connected via a conduit to a pressurized source of (fresh water) water 71 . Fresh water in the current context is water that has not dissolved a significant amount of ammonia, so it still has little potential to absorb ammonia. The water level in the pressure vessel 58 is regulated between an upper and a lower level. Gaseous ammonia supplied to the pressure vessel 58 is absorbed into water to form aqueous ammonia. The pressure in the pressure vessel is regulated and maintained at an appropriate high pressure, since water can absorb a greater amount of gaseous ammonia at higher pressures. The pressure vessel 58 is provided with an ammonia water outlet. The amount of fresh water allowed into the pressure vessel 58 and the amount of ammonia water discharged from the pressure vessel 58 are controlled to ensure that there is sufficient capacity to absorb the ammonia. The ammonia water outlet is connected to the third return line 55 through the ammonia water discharge conduit 75. The ammonia water discharge conduit 75 includes a valve 76 for controlling the flow from the pressure vessel 58 to the third return line 55. From the third return line 5, aqueous ammonia is conveyed to the SCR reactor where it is used as a reducing agent, or to the low pressure ammonia feed line where it is used as a fuel in the engine as described in more detail below. The third purge line 47 includes a pressure regulating valve 74, which opens when a predetermined pressure in the third purge line 47 is exceeded. This predetermined pressure ensures that the gaseous ammonia is instead routed to a cascade of three absorption tanks connected in series: the first absorption tank (61), the intermediate absorption tank (63) and the last absorption tank (65). ) corresponds to the maximum pressure at which it can operate. In another embodiment, control of the gaseous ammonia flow from the third purge line 47 to the pressure vessel 58 or water tank 61, 63, 65 cascade is instead controlled by an electronic control valve (not shown) of the pressure regulating system shown. city) is controlled by

The last absorption tank 65 is provided with a fourth vent 66 connecting the last absorption tank 65 with the surroundings. In one embodiment, there are more than three absorption tanks to obtain a lower concentration of ammonia in the atmosphere above the water in the last absorption tank (65), and thus a lower concentration in the gas exiting through the fourth vent (66). concentration of ammonia is obtained.

The absorption efficiency of the absorption tank cascade is maintained by regularly replacing the water in the last absorption tank 65 from a pressurized source of (fresh) water 71 and reusing slightly contaminated water from the upstream tank. Therefore, the water in the last tank 65 in which some ammonia has been absorbed replaced by the water in the water supply source 71 passes through the first water return line 67 controlled by the first water return valve 68 to the intermediate absorption tank ( 63) is transported. Similarly, the water in the intermediate absorption tank 63 is conveyed to the first absorption tank 61 through the second water return line 69 controlled by the second water return valve 70 . The system is configured to compensate for evaporation of ammonia water and water in the absorption tanks 61, 63, 65 removed from the first ammonia tank 61. That is, the water level in the absorption tank is maintained between the minimum and maximum values indicated by dotted lines in FIG. 4 .

The ammonia gas (fume) above the water in the first absorption tank (61) flows to the intermediate absorption tank (63) through the first ammonia vent line (62). The ammonia gas above the water in the intermediate absorption tank (63) flows through the second ammonia vent line (64) to the last absorption tank (65). The process is preferably driven by the pressure of the purge process.

The ammonia concentration of the fourth vent 66 is low enough to be vented to the surroundings. However, where compliance is required, ammonia from vent masts can be further reduced by introducing additional absorption towers in which the absorption medium is acid. The acid protonates NH3(aq) under the formation of ammonium hydroxide, reducing ammonia emissions to the atmosphere.

As a result, the ammonia concentration in water in the first absorption tank 61 is higher than that in the intermediate absorption tank 63 and the ammonia concentration in water in the intermediate absorption tank 63 is higher than that in the last ammonia absorption tank 65. .

The ammonia water in the first absorption tank 61 is removed from the first absorption tank 61 through the first ammonia water return line 51 including the return pump 52 . The second ammonia water return line 53 including the first return valve 54 connects the first ammonia water return line 51 to the low pressure ammonia supply line 32 . Therefore, when the first return valve 54 is opened, the ammonia water having a relatively high ammonia concentration from the first absorption tank 61 is mixed with the fuel from the ammonia storage tank 31 and absorbed by the ammonia absorption system 60. The released ammonia is thereby reused as fuel for the engine. A third ammonia water return line 55 comprising a second return valve 56 connects the first return line 51 to the reducing agent inlet associated with the SCR reactor 28 . The reducing agent inlet may be part of the SCR reactor 28 or may be located in the exhaust gas flow path upstream of the SCR reactor 28. Therefore, when the second return valve 56 is opened, the ammonia absorbed by the ammonia absorption system 60 is used as a reducing agent in the SCR reactor 28.

The cascade of water tank 61, 63, 65 system is completely passive. That is, there is no need to use pumps or other auxiliary systems when barrier absorption of ammonia is required. Thus, the system is inherently reliable and available when needed.

The low pressure ammonia supply line 32, the medium pressure ammonia supply line 36 and the ammonia return line 38 are, in an embodiment, entirely or partly constructed of double-walled piping with a space between the inner pipe and the outer pipe. In this embodiment, the space between the inner tube and the exterior is connected to the purge system, so that the ammonia fuel inadvertently leaked into the space between the inner tube and the exterior is connected to the ammonia absorption system 60 to be absorbed. Thus, absorption in the ammonia absorption system 60 avoids the inadvertent introduction of ammonia into the surroundings in the event of a leak in any fuel line. Preferably, a detection system is provided that detects the presence of ammonia in the space between the inner and outer piping, allowing ammonia to be shut down in operation if ammonia is detected in the space, followed by a subsequent purge of the ammonia fuel system and the absorbent purge system. (60) followed by absorption of residual ammonia.

The electronic control unit 100 is connected via signal lines or wirelessly to the pumps and valves of the fuel system 30, the purge system and the ammonia absorption system 60. The electronic control unit 100 is configured to control these components by, for example, adjusting the speed of the pump and controlling the opening and closing of each valve to ensure operation of the fuel system and the purge and absorption system as described above.

Figure 5 shows a second embodiment of an engine with a fuel, purge and ammonia absorption system. In these embodiments, structures and features identical or similar to corresponding structures and features previously described or illustrated herein are denoted by reference numerals as previously used for simplicity. The embodiment according to FIG. 5 shows that the cascade water tank is packed. It is essentially the same as the embodiment according to FIG. 5 except that it is replaced by an absorption tower 78 . The packed absorption tower 78 is used for ammonia gas absorption and subsequent discharge of ammonia water. Gas-liquid (water) contact in the packed absorption tower 78 is continuous. Water flows down the absorber through the packing surfaces and gaseous ammonia moves countercurrently up the absorber 78. Packed absorption tower 78 is a vessel having packed sections. The absorption tower is filled with one or more structured packing sections stacked on top of each other. Packed absorption tower 78 has an inlet for receiving ammonia gas connected to third purge line 47 via pressure regulating valve 74. The packed absorption tower has an ammonia water outlet connected to the first ammonia water return line 51. A source of pressurized (fresh water) water 71 is connected to the packed absorber 78 and to the inlet disposed above the structured packing section. Vents 76 are provided to ventilate the space above the packed section to ambient. The pressurized (freshwater) water source 71 water flow is scaled to match the size of the gaseous ammonia flow into the packed absorber 78. The amount of ammonia water collected at the bottom of the packed absorption tower 78 is adjusted and transported to an intermediate ammonia water storage tank (not shown) if necessary.

Various aspects and embodiments have been described in connection with various embodiments herein. However, other modifications to the disclosed embodiments may be understood and effected by those skilled in the art when practicing the claimed subject matter upon a study of the drawings, disclosure and appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality.

Reference signs used in the claims should not be construed as limiting the scope. Unless otherwise indicated, the drawings are intended to be read along with the specification (eg, cross-hatching, parts arrangement, proportions, degrees, etc.) and are to be considered part of the entire written description of the present disclosure.

Claims (15)

A large two-stroke single-flow scavenging turbocharged internal combustion engine having at least one mode of operation in which the primary fuel is ammonia, comprising:
- at least one cylinder having a cylinder liner (1), a reciprocating piston (10) therein and a cylinder cover (22) covering the cylinder;
- a combustion chamber formed inside the cylinder between the reciprocating piston (10) and the cylinder cover (22);
- an ammonia fuel system (30) configured to supply pressurized ammonia to fuel valves (50, 50') disposed on the cylinder cover (22) or the cylinder liner (1);
- ammonia absorption system 60; and
-Including ammonia discharge channels (42, 44, 47),
The ammonia discharge passages 42, 44, and 47 connect the outlet of the ammonia fuel system 30 to the inlet of the ammonia absorption system 60,
wherein the ammonia absorption system (60) absorbs ammonia supplied through the discharge passage into water and contains the water during use to form ammonia water.
According to claim 1,
said ammonia absorption system (60) comprising at least one container (58, 61, 63, 65, 78) at least partially filled with water during use;
The at least one container (58, 61, 63, 65, 78) preferably includes a water inlet for connection to a water source (71), and preferably includes an ammonia water outlet for discharging the ammonia water, Large two-stroke single-flow scavenging turbocharged internal combustion engine.
According to claim 2,
wherein the ammonia water outlet is connected to the ammonia fuel system (30) for combusting the ammonia water in the engine.
According to claim 2,
An SCR reactor 28 is included in the exhaust gas flow path of the engine,
wherein the ammonia water outlet is connected to the reducing agent inlet associated with the SCR reactor (28).
According to claim 1,
The ammonia absorption system (60) includes a pressure vessel (58) that is at least partially filled with water during use;
The pressure vessel (58) is preferably provided with a cooling system for lowering the temperature of the pressure vessel (58);
The pressure vessel (58) preferably includes a gaseous ammonia inlet for aspirating gaseous ammonia;
The pressure vessel (58) is preferably connected to a water source (71),
The pressure vessel (58) preferably has an ammonia water outlet for discharging the ammonia water.
According to claim 1,
The ammonia absorption system 60 includes a packed absorption tower 78,
The packed absorption tower 78 preferably includes a gaseous ammonia inlet for sucking gaseous ammonia,
The ammonia absorption system (60) is preferably connected to a water source (71),
The ammonia absorption system (60) preferably has an ammonia water outlet for discharging the ammonia water.
According to claim 1,
The ammonia absorption system (60) comprises cascade water tanks (61, 63, 65) at least partially filled with water during use, preferably comprising a gaseous ammonia inlet and a gaseous ammonia outlet, a water inlet and an ammonia water outlet. A first water tank (61), preferably a subsequent water tank (62, 63) comprising a gaseous ammonia inlet connected to the gaseous ammonia outlet of the first water tank (61) and water in the first water tank (61) Including an ammonia water outlet connected to the inlet and the ammonia vapor outlet,
The cascade water tanks (61, 63, 65) are preferably configured for countercurrent of the flow of water to the flow of gaseous ammonia, and in use the tank 61 most upstream of the flow of gaseous ammonia is in the tank (61). An ammonia water outlet is provided with the highest ammonia concentration in water, and the most downstream tank 65 in the flow of gaseous ammonia during use has the lowest ammonia concentration in the water in the tank 65, and the most downstream tank 65 in the flow of gaseous ammonia. A large two-stroke single-flow scavenging turbocharged internal combustion engine, preferably provided with a vent for discharging gaseous substances from said tank (65).
According to claim 1,
The ammonia fuel system (30) includes a purge system configured to evacuate ammonia from the fuel system (30) to the ammonia absorption system (60), the purge system preferably including a pressurized nitrogen source (40) ,
the pressurized nitrogen source (40) is connected to the fuel system, preferably through a purge valve (41);
The purge system preferably uses an ammonia discharge passage to purge ammonia from the ammonia fuel system (30) to the ammonia absorption system (60).
According to claim 8,
The ammonia fuel system 30 includes an intermediate pressure ammonia supply line 36 and an ammonia return line 38, a first purge line 42 connecting the intermediate pressure ammonia supply line 36 to the ammonia absorption system 60, A second purge line 44 connecting the ammonia return line 38 to the ammonia absorption system 60 and preferably the intermediate pressure ammonia supply line 36 and the ammonia return line 38 to the ammonia absorption system A large two-stroke single-flow scavenging turbocharged internal combustion engine comprising a valve arrangement for selective connection to (60).
According to claim 9,
a knockout drum (46) in the first and/or second purge line (42, 44);
The knockout drum (46) is configured to separate liquid ammonia from gaseous ammonia, the knockout drum (46) includes a gaseous ammonia outlet and a liquid ammonia outlet, the gaseous ammonia outlet being connected to the ammonia absorption system (60). wherein the liquid ammonia outlet is preferably connected to a recovery tank (57), which in turn is connected to the ammonia fuel system (30).
According to claim 1,
The ammonia fuel system (30) includes supply lines (32, 36) and a return line (38),
The pipe forming the supply lines 32 and 36 and the return line 38 includes a double wall pipe, and a space between an inner pipe of the double wall pipe and an outer pipe of the double wall pipe absorbs the ammonia by the ammonia discharge passage. A large two-stroke single-flow scavenging turbocharged internal combustion engine, fluidly connected to system 60.
According to claim 1,
The ammonia fuel system 30 includes a liquid ammonia fuel tank 31 and a low pressure ammonia supply line 32 connecting the liquid ammonia fuel tank 31 to the inlet of the intermediate pressure fuel pump 35 by the action of the low pressure pump. include,
The ammonia fuel system (30) preferably includes a medium pressure supply line (36) connecting the outlet of the medium pressure pump (35) to the inlet of the fuel valve (50, 50');
The ammonia fuel system (30) is preferably a large two-stroke single-flow scavenge type, including a return line (38) connecting the outlet of the fuel valves (50, 50') to the inlet of the intermediate pressure fuel pump (35). Turbocharged internal combustion engine.
A method for managing ammonia in a large two-stroke single-flow scavenging turbocharged internal combustion engine having at least one mode of operation in which the primary fuel is ammonia, the engine comprising:
- at least one cylinder with a cylinder liner (1) and a reciprocating piston (10) therein and a cylinder cover (22) covering the cylinder,
- a combustion chamber (15) formed inside the cylinder between the reciprocating piston (10) and the cylinder cover (22);
- an ammonia fuel system (30) configured to supply pressurized ammonia to fuel valves (50, 50') disposed on the cylinder cover (22) or the cylinder liner (1); and
- large two-stroke single-flow scavenging turbocharged internal combustion, comprising conveying excess gaseous ammonia from the fuel system (30) to the ammonia absorption system (60) and absorbing the gaseous ammonia from water to form ammonia water How to manage ammonia in organs.
According to claim 13,
Preferably, separating liquid ammonia and gaseous ammonia generated from the excess ammonia using a knockout drum 46, conveying the gaseous ammonia to the ammonia absorption system 60, and absorbing the ammonia into water A method for managing ammonia in a large two-stroke single-flow scavenging turbocharged internal combustion engine, comprising the step of forming aqueous ammonia.
The method of claim 13 or 14,
A method for managing ammonia in a large two-stroke single flow scavenging turbocharged internal combustion engine comprising the step of using the ammonia water as a fuel for the engine or as a reducing agent for an SCR reactor (28) of the engine.

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