Large two-stroke turbocharged single-flow scavenged internal combustion engine and method of operating the same

Abstract

A large two-stroke turbocharged single-flow scavenging internal combustion engine and a method for operating the engine, the method being carried out by the following steps: supplying a carbon-based fuel to a combustion chamber; causing the carbon-based fuel to burn in the combustion chamber to produce combustion gas containing carbon dioxide; recirculating a portion of the combustion gas and discharging another portion of the combustion gas as exhaust gas; supplying pressurized scavenging gas to the combustion chamber, the pressurized scavenging gas containing at least 40% by mass of recycled combustion gas, preferably 40% to 55% by mass; separating carbon dioxide from the exhaust gas in a carbon dioxide separation process; and storing the separated carbon dioxide in a storage unit (80).

Description

Technical Field

[0001] The present disclosure relates to a large two-stroke internal combustion engine, in particular a large two-stroke uniflow scavenged internal combustion engine with a crosshead operating on a carbon-based fuel (gaseous or liquid fuel), and a method of operating an engine of this type to reduce carbon dioxide emissions. Background Art

[0002] Large two-stroke turbocharged single-flow scavenged internal combustion engines with a crosshead are used, for example, for the propulsion of large ocean-going ships or as main engines in power plants. These two-stroke diesel engines are constructed differently from any other internal combustion engine, not only because of the sheer size of the engine. The exhaust valves of a two-stroke diesel engine can have a weight of up to 400 kg, the piston has a diameter of up to 100 cm, and the maximum operating pressure in the combustion chamber is typically several hundred bar. The forces involved at these high pressure levels and piston sizes are enormous.

[0003] Large two-stroke turbocharged internal combustion engines operate on liquid fuels such as fuel oil, marine diesel, heavy fuel oil, ethanol, dimethyl ether (DME) or gaseous fuels such as natural gas (LNG), petroleum gas (LPG), methanol, or ethane.

[0004] Engines operating with gaseous fuel can operate according to the Otto cycle, in which gaseous fuel is allowed to enter through a fuel valve arranged in the middle of the length of the cylinder liner or in the cylinder cover, that is, these engines allow gaseous fuel to enter during the full start of the upward stroke of the piston (from BDC to TDC) before the exhaust valve closes, and these engines compress the mixture of gaseous fuel and scavenging air in the combustion chamber and ignite the compressed mixture at or near TDC by a timed ignition device such as liquid fuel injection.

[0005] An engine operating with liquid fuel and an engine operating with gaseous fuel injected by high pressure injects gaseous or liquid fuel when the piston approaches TDC or is at TDC, that is, when the compression pressure in the combustion chamber reaches or approaches the maximum value of the compression pressure, and therefore, an engine operating with liquid fuel and an engine operating with gaseous fuel injected by high pressure operate according to the Diesel cycle, that is, by compression ignition.

[0006] Liquid and gaseous fuels used in known large two-stroke turbocharged single-flow scavenged internal combustion engines generally contain carbon, i.e., these fuels are carbon-based fuels, and the combustion of these fuels results in the production of carbon dioxide which is emitted into the atmosphere. Carbon dioxide emissions are generally considered to be harmful to the environment and should be minimized or avoided.

[0007] KR20180072552 discloses a large two-stroke turbocharged single-flow scavenging internal combustion engine having a plurality of cylinders, and each of the cylinders is provided with: a scavenging port; a scavenging valve; an exhaust accommodating portion connected to the cylinder via a separate exhaust valve; a turbocharger; an exhaust duct connecting the outlet of the exhaust accommodating portion to the turbine of the turbocharger; a turbocharger compressor of the turbocharger driven by the turbine; a scavenging duct connecting the outlet of the turbocharger compressor to the inlet of the scavenging accommodating portion, the scavenging duct comprising: a scavenging cooler; a scavenging accommodating portion connected to the cylinder via a separate scavenging port; an exhaust gas recirculation duct for circulating a portion of the exhaust gas back to the cylinder, the exhaust gas recirculation duct comprising: a blower or a compressor for forcing the recirculated exhaust gas back to the cylinder; a cylinder bypass duct for bypassing the cylinder by transporting a portion of the high-temperature scavenging gas from the scavenging duct upstream of the scavenging cooler to the turbine of the turbocharger; and a boiler. The engine is configured to transport at least a first portion of the exhaust gas from the cylinder through the boiler. Summary of the invention

[0008] It is an object of the present invention to provide an engine and a method which overcome or at least reduce the above mentioned problems.

[0009] The above objects and other objects are achieved by the features of the present application.Other embodiments are apparent from the present specification and the accompanying drawings.

[0010] According to a first aspect, a large two-stroke turbocharged single-flow scavenging internal combustion engine with a crosshead is provided, the engine comprising: a plurality of combustion chambers, each combustion chamber being bounded by a cylinder liner, a piston configured to reciprocate in the cylinder liner, and a cylinder cover; a scavenging port, the scavenging port being arranged in the cylinder liner for allowing scavenging gas to enter the combustion chamber; an exhaust outlet, the exhaust outlet being arranged in the cylinder cover and controlled by an exhaust valve; a fuel system, the fuel system being configured to supply a carbon-based fuel to the combustion chamber, the combustion chamber being configured to burn the carbon-based fuel to produce a combustion gas containing carbon dioxide, the combustion chamber being connected to a scavenging air receiver via the scavenging port, and being connected to a combustion gas receiver via the exhaust outlet; an exhaust gas recirculation system, the exhaust gas recirculation system being configured to recirculate a portion of the combustion gas from the combustion chamber to the scavenging air receiver, the exhaust gas recirculation system being configured to recirculate a portion of the combustion gas from the combustion chamber to the scavenging air receiver, the exhaust gas recirculation system being configured to recirculate a portion of the combustion gas from the combustion chamber to the scavenging air receiver, the exhaust gas recirculation system being configured to recirculate a portion of the combustion gas from the combustion chamber to the scavenging air receiver, the exhaust gas recirculation system being configured to recirculate a portion of the combustion gas from the combustion chamber to the The circulation system includes a blower for assisting the flow of combustion gases to a scavenging air receiver; an exhaust system, the exhaust system being configured to discharge another portion of the combustion gases from the combustion chamber as exhaust gas, the exhaust system including a turbine of a turbocharger system driven by exhaust gas; an air inlet system, the air inlet system including a compressor of the turbocharger system, the compressor being configured to supply pressurized scavenging air to the scavenging air receiver, the exhaust system including a carbon dioxide separation system and a carbon dioxide storage unit, the carbon dioxide storage unit being connected to an outlet of the carbon dioxide separation system, and the carbon dioxide separation system being configured to: receive exhaust gas; separate at least a portion of the carbon dioxide in the exhaust gas from the exhaust gas, preferably by liquefying and / or solidifying the carbon dioxide to separate at least a portion of the carbon dioxide in the exhaust gas from the exhaust gas; and transmit the separated carbon dioxide to the carbon dioxide storage unit.

[0011] By operating the engine with exhaust gas recirculation, the concentration of carbon dioxide in the exhaust gas is increased, thereby making separation of carbon dioxide from the exhaust gas more efficient, and by separating carbon dioxide from the exhaust gas and storing the separated carbon dioxide, carbon dioxide emissions caused by the engine are reduced.

[0012] In a possible implementation of the first aspect, the engine comprises a controller configured to adjust the mass percentage of recirculated combustion gas in the scavenging gas to at least 40%, preferably to adjust the mass percentage of recirculated combustion gas in the scavenging gas to between 40% and 55%.

[0013] In a possible implementation of the first aspect, the controller is configured to control the speed of the blower to adjust the percentage of recirculated combustion gas in the purge gas.

[0014] In a possible embodiment of the first aspect, the engine comprises a combustion gas to water cooler, preferably the engine comprises a combustion gas to seawater cooler, the combustion gas to water cooler being preferably arranged upstream of the position where the combustion gas flow from the engine is divided into a part to be recirculated and a other part to be discharged.

[0015] In a possible implementation of the first aspect, the engine includes a combustion gas to cooling medium heat exchanger and a cooling facility, the cooling facility being configured to circulate the cooling medium through the combustion gas to cooling medium heat exchanger, the combustion gas to cooling medium heat exchanger being preferably arranged downstream of a position at which a combustion gas flow from the engine is divided into a recirculated portion and another portion that is discharged.

[0016] In a possible implementation of the first aspect, a heat exchanger of the combustion gases against a cooling medium is connected to the cooling facility.

[0017] In a possible implementation of the first aspect, the engine comprises a cooler downstream of the turbine for cooling the exhaust gas for liquefying and / or solidifying carbon dioxide in the exhaust gas.

[0018] In a possible implementation of the first aspect, the cooler is connected to the cooling device.

[0019] In a possible implementation of the first aspect, the controller is configured to control the operation of the engine such that the temperature of the exhaust gas is -82 degrees Celsius or less when the exhaust gas reaches atmospheric pressure downstream of the turbine.

[0020] In a possible embodiment of the first aspect, the turbine is mechanically coupled to and drives the compressor, preferably the turbine drives the compressor with the assistance of an electric drive motor. For the turbine to provide sufficient expansion to provide sufficient cooling of the exhaust gas, there will be operating conditions where the turbine does not deliver sufficient energy to operate the compressor, and under these operating conditions, additional energy needs to be added to the turbocharger system driven by the electric drive motor.

[0021] In a possible embodiment of the first aspect, the compressor is driven by an electric drive motor, and wherein the turbine drives a generator or an alternator. In this arrangement of the turbocharger system, the additional energy that may be required by the turbocharger system can be transmitted by the electric drive motor driving the compressor from an external power source, which can be in the form of a generator or in the form of an alternator driven by the engine or a generator set associated with the engine.

[0022] In a possible implementation of the first aspect, the engine operates according to the Otto cycle and during the stroke of the piston from bottom dead center (BDC) to top dead center (TDC), gaseous fuel is admitted from the fuel valve into the combustion chamber.

[0023] In a possible implementation of the first aspect, the engine operates according to a diesel cycle, and when the piston approaches top dead center (TDC), gaseous or liquid fuel is injected from a fuel valve into the combustion chamber.

[0024] According to a second aspect, a method for operating a large two-stroke turbocharged single-flow scavenging internal combustion engine having multiple combustion chambers is provided, the method comprising: supplying a carbon-based fuel to the combustion chamber; burning the carbon-based fuel in the combustion chamber to produce a combustion gas containing carbon dioxide; recirculating a portion of the combustion gas and discharging another portion of the combustion gas as exhaust gas; supplying pressurized scavenging gas to the combustion chamber, the pressurized scavenging gas containing at least 40% by mass of recirculated combustion gas, preferably, the pressurized scavenging gas containing 40% to 55% by mass of recirculated combustion gas; separating carbon dioxide from the exhaust gas in a carbon dioxide separation process; and storing the separated carbon dioxide in a storage unit.

[0025] By operating the engine at a high exhaust gas recirculation ratio, the concentration of carbon dioxide in the exhaust gas is increased, thereby facilitating separation of carbon dioxide from the exhaust gas, and by separating carbon dioxide from the exhaust gas and storing the carbon dioxide, emissions of carbon dioxide caused by the engine are avoided or at least reduced.

[0026] In a possible embodiment of the second aspect, the method comprises solidifying (freezing) at least a portion of the carbon dioxide in the exhaust gas. By freezing the carbon dioxide, it becomes relatively simple to separate the carbon dioxide from other components of the exhaust gas. In addition, storing carbon dioxide in solid form requires little space and can be carried out in containers that do not require pressurization.

[0027] In a possible implementation of the second aspect, the method comprises subjecting the exhaust gas to one or more cooling and expansion processes to liquefy and / or solidify the carbon dioxide downstream of the turbine.

[0028] In a possible embodiment of the second aspect, the method comprises storing carbon dioxide in liquid or solid form in a storage unit.

[0029] In a possible implementation of the second aspect, the method includes controlling the speed of a blower in the exhaust gas recirculation system to adjust the percentage of recirculated combustion gases in the pressurized scavenging gas.

[0030] In a possible implementation of the second aspect, at least a portion of the expansion process is carried out in a turbine.

[0031] In a possible implementation of the second aspect, the engine comprises a combustion gas relative to water cooler, preferably, the combustion gas relative to water cooler is arranged upstream of the position where the combustion gas flow from the engine is divided into a part for recirculation and a part to be discharged, preferably, the engine comprises an exhaust gas relative to seawater cooler, preferably, the exhaust gas relative to seawater cooler is arranged upstream of the position where the combustion gas flow from the engine is divided into a part for recirculation and a part to be discharged, and the method comprises: cooling the combustion gas with a combustion gas relative to water cooler, preferably, cooling the combustion gas to a temperature below 40 degrees Celsius, more preferably, cooling the combustion gas to a temperature of 31 degrees Celsius or lower.

[0032] In a possible embodiment of the second aspect, the engine comprises a heat exchanger of exhaust gas relative to a cooling medium and a cooling facility configured to recirculate the cooling medium through the heat exchanger of combustion gas relative to the cooling medium, preferably cooling the combustion gas to a temperature below -10 degrees Celsius, more preferably cooling the combustion gas to a temperature of -15 degrees Celsius or less.

[0033] In a possible embodiment of the second aspect, the solidified water content (ice) in the exhaust gas is separated from the exhaust gas, for example by gravity or centrifugal separation processes, and stored or disposed of.

[0034] In a possible embodiment of the second aspect, the engine includes a cooler located downstream of the turbine, which is used to further cool the exhaust gas for solidifying the carbon dioxide in the exhaust gas, preferably cooling the exhaust gas to a temperature below -80 degrees Celsius or below, preferably cooling the exhaust gas to a temperature below -80 degrees Celsius or below at atmospheric pressure.

[0035] In a possible implementation of the second aspect, the method comprises compressing air with a compressor and mixing the combustion gas with the compressed air to obtain the purge gas.

[0036] In a possible implementation of the second aspect, the method includes pressurizing the recirculated combustion gas with a blower compressor before the combustion gas is mixed with the compressed air.

[0037] These and other aspects will be apparent from the embodiments described hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In the following detailed portion of the present disclosure, various aspects, embodiments and implementations will be described in more detail with reference to example implementations shown in the accompanying drawings, in which:

[0039] Figure 1 is a front view of a large two-stroke diesel engine according to an example embodiment,

[0040] Figure 2 yes Figure 1 Side view of a medium to large two-stroke engine.

[0041] Figure 3 In the implementation method, Figure 1 Schematic representation of a large two-stroke engine,

[0042] Figure 4 In another embodiment, according to Figure 1 A schematic representation of a large two-stroke engine, and

[0043] Figure 5 In yet another embodiment, Figure 1 Schematic representation of a large two-stroke engine. DETAILED DESCRIPTION

[0044] In the following detailed description, the internal combustion engine will be described with reference to a large two-stroke, low speed, turbocharged, internal combustion crosshead engine in an example embodiment. Figure 1 , Figure 2 and Figure 3 An embodiment of a large, low speed, turbocharged, two-stroke diesel engine having a crankshaft 8 and a crosshead 9 is shown. Figure 1 and Figure 2 They are the front view and the side view respectively. Figure 3 yes Figure 1 and Figure 2Schematic representation of the intake and exhaust systems in an embodiment of a large low-speed turbocharged two-stroke diesel engine in FIG. In this embodiment, the engine has four cylinders arranged in a straight line. However, a large low-speed turbocharged two-stroke internal combustion engine may have 4 and 14 cylinders arranged in a straight line, wherein the cylinder liners are carried by the engine frame 11. The engine may be used, for example, as a main engine in a ship or as a stationary engine for operating a generator in a power station. For example, the total output of the engine may be in the range from 1,000 kW to 110,000 kW.

[0045] In the present example embodiment, the engine is a two-stroke single-flow scavenging type engine having scavenging ports 18 located in the lower region of the cylinder liner 1, and a central exhaust valve 4 located in the cylinder cover 22 at the top of the cylinder liner 1. When the piston 10 is located below the scavenging ports 18, scavenging air passes from the scavenging air receiver 2 through the scavenging ports 18 of each cylinder liner 1. When the piston 10 is moving upward (moving from BDC to TDC) and before the piston 10 passes the fuel valve 30 (gas inlet valve), a gaseous fuel (e.g., methanol, petroleum gas or LPG, natural gas LNG, or ethane) is allowed to enter from the fuel valve 30 under the control of the electronic controller 40, and / or, when the piston 10 is at or near TDC, a liquid fuel (e.g., fuel oil) is injected at high pressure (preferably 300 bar or more) through the liquid fuel valve 50. The fuel gas enters at a relatively low pressure, which is less than 30 bar, preferably less than 25 bar, and more preferably less than 20 bar. Preferably, the fuel valves 30 are evenly distributed around the circumference of the cylinder liner and are placed in a central region of the length of the cylinder liner 1. The admission of gaseous fuel occurs when the compression pressure is relatively low, i.e. much lower than the compression pressure when the piston 10 reaches TDC, thus allowing admission at a relatively low pressure.

[0046] The piston 10 in the cylinder liner 1 compresses the charge of gaseous fuel and scavenging gases (or compresses the scavenging gases in the case of operation with liquid fuel injection only at TDC), and ignition at or near TDC is triggered by the following method: liquid fuel is injected at high pressure from a liquid fuel valve 50 preferably arranged in the cylinder cover 22, or by compression in the case of liquid fuel injection only at or near TDC. Combustion then occurs and combustion gases containing carbon dioxide are produced.

[0047] When the exhaust valve 4 is open, the combustion gas flows through the combustion gas duct associated with the cylinder into the combustion gas receiver 3 and then onwards through the combustion gas duct 19 including the combustion gas relative to water cooler 65. If the engine is installed in a ship, the combustion gas relative to water cooler 65 works with seawater. The activity of the combustion gas relative to water cooler 65 is controlled by the controller 40 and the combustion gas is cooled so that the combustion gas is cooled from 425 degrees Celsius to 475 degrees Celsius at the inlet of the combustion gas relative to water cooler 65 to a temperature of less than 40 degrees Celsius, preferably less than 35 degrees Celsius, more preferably less than 31 degrees Celsius at the outlet of the combustion gas relative to water cooler 65. At the location of the combustion gas relative to water cooler 65, preferably at a downstream location, the flow of the combustion gas is divided into a part flowing to the exhaust gas recirculation system 60 and another part flowing to the exhaust system. The exhaust gas recirculation system 60 is connected to a scavenging system as further described below. The exhaust gas recirculation system 60 includes a conduit connected to the scavenging gas and may include a scrubber 70 (preferably water-operated) for cleaning the combustion gases. The exhaust gas recirculation system 60 also includes a blower 75 (preferably driven by an electric drive motor 76) for forcing the combustion gases through the exhaust gas recirculation system 60 to the scavenging system. The operation of the blower 75 is controlled by the controller 40. In an embodiment, the controller 40 adjusts the combustion gas ratio (by mass) in the scavenging gas by adjusting the operation of the blower 75. The controller 40 is configured in an embodiment to adjust the combustion gas ratio (by mass) in the scavenging gas to more than 40%, preferably more than 45%, and most preferably between 40% and 55%. The combustion gas ratio is defined as the percentage of the combustion gas mass to the total gas mass introduced into the engine.

[0048] The exhaust system includes an exhaust duct 63, which includes a heat exchanger 66 for combustion gas relative to a cooling medium, and the exhaust duct leads to the turbine 6 of the turbocharger 5. The heat exchanger 66 for combustion gas relative to the cooling medium is operably connected to a cooling facility 68. The cooling facility 68 is configured to circulate the cooling medium through the heat exchanger 66 for combustion gas relative to the cooling medium to cool the exhaust gas at the outlet of the heat exchanger 66 for combustion gas relative to the cooling medium to a temperature below -10 degrees Celsius, more preferably -15 degrees Celsius or below. The water in the exhaust gas is thus solidified (to form ice or snow), and is separated under gravity or centrifugal action and removed through a drain 64. The cooling medium (refrigerant) may have a temperature in the range of -20 degrees Celsius to -30 degrees Celsius at the cooling medium inlet of the heat exchanger 66 for combustion gas relative to the cooling medium. Suitable cooling media (refrigerants) are, for example, ammonia, propane, isobutane, carbon dioxide and other known cooling media for industrial cooling facilities. The operation of the combustion gas to cooling medium heat exchanger 66 is controlled by the controller 40 so that the temperature of the exhaust gas at the outlet of the combustion gas to cooling medium heat exchanger 66 is at a desired temperature.

[0049] The exhaust gas flows from the outlet of the heat exchanger 66 of the combustion gases to the cooling medium to the inlet of the turbine 6. At the outlet of the turbine 6, the exhaust gas has a temperature of below -80 degrees Celsius, preferably below -82 degrees Celsius, and is at ambient (atmospheric) pressure due to expansion in the turbine 6. Under these conditions, the carbon dioxide in the exhaust gas solidifies (freezes) and is separated, for example, by gravity or centrifugal separation processes. The separated solid carbon dioxide is stored in the carbon dioxide storage unit 80. The remaining exhaust gas contains no carbon dioxide or only a small amount of carbon dioxide and is allowed to flow away through the outlet 21 and flow into the atmosphere.

[0050] In this embodiment, the engine includes a cooler 69 located downstream of the turbine 6 for further cooling the exhaust gas, preferably to a temperature of less than -80 degrees Celsius or below at atmospheric pressure, to solidify the carbon dioxide in the exhaust gas. In this embodiment, the solid carbon dioxide is separated in the cooler 69, at the outlet of the cooler 69, or just downstream of the cooler 69, for example, by gravity or centrifugal action. The separated solid carbon dioxide is stored in a carbon dioxide storage unit 80. The carbon dioxide stored in the carbon dioxide storage unit 80 can then be stored in a more permanent solution for storing the captured carbon dioxide.

[0051] The turbine 6 drives, via a shaft, a compressor 7 which is supplied with fresh air via an air inlet 12. The turbocharger 5 is assisted by an electric drive motor 77 which assists the turbocharger 5 when the turbine 6 does not provide sufficient power to drive the compressor 7.

[0052] The compressor 7 delivers the pressurized scavenging air to a scavenging air duct 13 leading to the scavenging air receiver 2. The scavenging air in the scavenging air duct 13 passes through an intercooler 14 for cooling the scavenging air.

[0053] The intercooler 14 connects the exhaust gas recirculation system 60 to the scavenging air duct 13 upstream (shown) or downstream (not shown). In this position, the recirculated combustion gases are mixed with the scavenging air to form scavenging gases. The controller 40 is configured to ensure that the scavenging gases contain 40% to 55% combustion gases by mass.

[0054] When the compressor 7 of the turbocharger 5 does not deliver sufficient pressure to the scavenging air receiver 2, i.e. at lower or partial load conditions of the engine, the cooled scavenging air or gas is passed via the auxiliary blower 16, which is driven by the electric motor 17, to pressurize the scavenging air flow. At higher engine loads, the turbocharger compressor 7 delivers sufficiently compressed scavenging air, and the auxiliary blower 16 is then bypassed via the non-return valve 15.

[0055] The controller 40 (electronic control unit) - which itself may include a plurality of interconnected electronic units including a processor and other hardware for performing the functions of the controller - generally controls the operation of the engine and performs control of, for example, gaseous fuel admission (amount and timing), liquid fuel injection (amount and timing), and the opening and closing of the exhaust valve 4 (timing and range of lift), the recirculated combustion gas ratio, and the operation of various coolers. Thus, the controller 40 receives various signals from sensors that inform the controller of the operating state of the engine (engine load, engine speed, blower speed, scavenging gas temperature, combustion gas temperature at different locations, exhaust gas temperature at different locations, pressure in the scavenging system, pressure in the combustion chamber, pressure in the exhaust system, and pressure in the exhaust gas recirculation system). Preferably, the engine includes a variable time exhaust valve actuation system that allows individual control of the exhaust valve timing for each combustion chamber. The controller 40 is connected via signal lines or wireless connections to the fuel valve 30, the liquid fuel valve 50, the exhaust valve actuator, an angular position sensor that detects the crankshaft angle and generates a signal representing the crankshaft position, and a pressure sensor, which is preferably in the cylinder cover 22 or alternatively in the cylinder liner 1, thereby generating a signal representing the combustion chamber pressure.

[0056] Depending on the engine size, the cylinder liner 1 can be manufactured in different sizes, with the cylinder bore diameter typically ranging from 250 mm to 1000 mm and a corresponding typical length ranging from 1000 mm to 4500 mm.

[0057] The cylinder liner 1 is installed in a cylinder frame 23, wherein a cylinder cover 22 is placed on the top of each cylinder liner 1, and the cylinder cover and the cylinder liner are in airtight engagement. The piston 10 is arranged to reciprocate between the bottom dead center (BDC) and the top dead center (TDC). These two positions are separated by a 180-degree rotation of the crankshaft 8. The cylinder liner 1 is provided with a plurality of cylinder lubrication holes distributed in the axial direction, and the cylinder lubrication holes are connected to a cylinder lubrication line, and when the piston 10 passes through the cylinder lubrication hole 25, the cylinder lubrication line provides a supply of cylinder lubrication oil, after which a piston ring (not shown) in the piston 10 distributes the cylinder lubrication oil on the running surface (inner surface) of the cylinder liner 1.

[0058] A liquid fuel valve 50 (usually more than one per cylinder, preferably three or four) is installed in the cylinder cover 22 and connected to a liquid fuel source (not shown). The liquid fuel valve 50 is preferably arranged around the exhaust valve 4, in particular around the central outlet (opening) in the cylinder cover 22 controlled by the exhaust valve 4. The timing and amount of liquid fuel injection are controlled by the controller 40. If the engine is operated in gaseous fuel mode, the liquid fuel valve 50 is only used to inject a small amount of ignition liquid (pilot). If the engine is operated in liquid fuel mode, the amount of liquid fuel required to operate the engine with the actual engine load is injected through the liquid fuel valve 50. The cylinder cover 22 can be provided with a pre-combustion chamber (not shown) and an end of the liquid fuel valve 50, typically, the end provided with a nozzle having one or more nozzle holes is arranged so that the pilot oil (ignition liquid) is injected into the pre-combustion chamber and atomized in the pre-combustion chamber to trigger ignition. The pre-combustion chamber helps to ensure reliable ignition. In an embodiment, the pre-combustion chamber is a double pre-combustion chamber, ie two pre-combustion chambers connected in series.

[0059] The fuel valve 30 is mounted in the cylinder liner 1 (or in the cylinder cover 22), wherein the nozzle of the fuel valve is substantially flush with the inner surface of the cylinder liner 1, and wherein the rear end of the fuel valve 30 protrudes from the outer wall of the cylinder liner 1. Typically, one or two fuel valves 30 are provided in each cylinder liner 1, but up to three or four fuel valves 30 may be provided, the fuel valves being distributed circumferentially around the cylinder liner 1 (preferably evenly distributed in the circumferential direction). In an embodiment, the fuel valve 30 is arranged substantially in the middle along the length of the cylinder liner 1. The fuel valve 30 is connected to a pressurized gaseous fuel source 40 (e.g., methanol, LPG, LNG, ethane or ammonia), i.e. the fuel is in the gaseous phase when it is delivered to the fuel valve 30. Since the gaseous fuel is allowed to enter during the stroke of the piston 10 from BDC to TDC, the pressure of the gaseous fuel source only needs to be higher than the pressure existing in the cylinder liner 1, and typically, a pressure of less than 20 bar is sufficient for the gaseous fuel delivered to the fuel valve 30. The fuel valve 30 is connected to a controller 40 which determines the timing of opening and closing of the fuel valve, as well as the duration of opening of the fuel valve 30 .

[0060] In an embodiment, the liquid fuel used for ignition is fuel oil, marine diesel, heavy fuel oil, ethanol, or dimethyl ether (DME).

[0061] The gaseous operating mode may be one of the engine's multiple operating modes. Other modes may include a liquid fuel operating mode, in which all fuel required for engine operation is provided in liquid form via the liquid fuel valve 50. In the gaseous fuel operating mode, the engine operates with gaseous fuel as the main fuel, i.e. providing the main part of the energy supplied to the engine, the gaseous fuel being admitted at a relatively low pressure during the piston's stroke from BDC to TDC, while in contrast, the liquid fuel constitutes a relatively small amount of fuel and makes only a relatively small contribution to the amount of energy supplied to the engine, the purpose of the liquid fuel being timed ignition, i.e. the liquid fuel acting as an ignition liquid.

[0062] Thus, the engine of this embodiment may be a dual fuel engine, ie the engine has a mode in which it operates entirely on liquid fuel and a mode in which it operates almost entirely on gaseous fuel.

[0063] The engine is operated by the following process: supplying a carbon-based fuel to a combustion chamber (liquid and / or gaseous fuel), burning the carbon-based fuel in the combustion chamber to produce a combustion gas containing carbon dioxide, circulating a portion of the combustion gas and discharging another portion of the combustion gas as exhaust gas, supplying pressurized scavenging gas to the combustion chamber so that the pressurized scavenging gas contains at least 40%, preferably 40% to 55% by mass of recycled combustion gas, separating carbon dioxide from the exhaust gas in a carbon dioxide separation process, and storing the separated carbon dioxide in a carbon dioxide storage unit 80.

[0064] In this process, the exhaust gas is subjected to a cooling and expansion process, which solidifies (freezes) the carbon dioxide in the exhaust gas at the outlet of the turbine 6 or downstream of the turbine 6 and in the cooler 69. The frozen carbon dioxide is separated, for example, in a gravity or centrifugal separation process and then stored in a solid form in the carbon dioxide storage unit 80. In an embodiment, the carbon dioxide storage unit 80 is an insulated non-pressurized container or tank.

[0065] The controller 40 controls the speed of the blower 75 in the exhaust gas recirculation system 60 to adjust the percentage of the recirculated combustion gas in the pressurized scavenging gas, preferably to adjust the percentage of the recirculated combustion gas in the pressurized scavenging gas to at least 40% by mass to increase the concentration of carbon dioxide in the combustion gas. In an embodiment, the controller 40 is configured to adjust the recirculated combustion gas ratio so that the carbon dioxide concentration in the combustion gas is at least twice as high as when compared to operation without exhaust gas recirculation.

[0066] At least a part of the expansion process of the exhaust gas is carried out in the turbine 6, so that the temperature and pressure of the exhaust gas are greatly reduced, preferably to atmospheric pressure and a temperature of -82 degrees or lower, so as to solidify the carbon dioxide in the exhaust gas.

[0067] Figure 4 Another embodiment of an engine is shown. In this embodiment, for the sake of brevity, structures and features that are the same or similar to corresponding structures and features described or shown previously herein are represented by the same reference numerals as used previously. In this embodiment, the engine and its operation are substantially the same as the previous embodiments, so only the differences from the previous embodiments will be described in detail.

[0068] In this embodiment, the compressor 7 is driven by an electric drive motor 78 and the turbine 6 drives a generator or alternator 79. In this arrangement of a turbocharger system, the additional energy required by the turbocharger system is delivered by the electric drive motor 78 driving the compressor 7. The electric drive motor 78 is therefore powered by a power source which may be in the form of a generator or alternator driven by the engine or a generator set associated with the engine.

[0069] In this embodiment, the engine is shown as a compression ignition engine (operating according to the diesel principle), in which a carbon-based fuel (gaseous or liquid) is injected at high pressure when the piston 10 is at or close to TDC. The engine shown requires neither a pre-combustion chamber nor a fuel admission fuel valve 30 in the cylinder liner 1. However, the engine according to this embodiment can also be operated according to the Otto principle, in which gaseous fuel is admitted during the stroke of the piston 10 from BDC to TDC.

[0070] In this embodiment, the controller 40 is configured to operate the engine so that the conditions (i.e., pressure and temperature) at the outlet of the turbine 6 cause the carbon dioxide in the exhaust gas to solidify, and the solidified carbon dioxide is separated at the outlet of the turbine 6 by gravity or a centrifugal separation process and stored in the carbon dioxide storage unit 80.

[0071] Figure 5 Another embodiment of an engine is shown. In this embodiment, for the sake of brevity, structures and features that are the same or similar to corresponding structures and features described or shown previously herein are represented by the same reference numerals as used previously. In this embodiment, the engine and its operation are substantially the same as the previous embodiments, so only the differences from the previous embodiments will be described in detail.

[0072] In this embodiment, the engine is shown as an air-intake engine operating according to the Otto principle, but it will be appreciated that this embodiment could operate as a high pressure fuel-injected engine operating according to the Diesel principle.

[0073] In this embodiment, no measures are taken to achieve a lower exhaust gas temperature than normal (conventional) at the outlet of the turbine 6. Therefore, neither a cooler of the combustion gases relative to water nor a cooler of the exhaust gases relative to the cooling medium connected to the cooling facility is required. Therefore, the temperature of the exhaust gases will be in the conventional temperature range of 180 degrees Celsius to 250 degrees Celsius.

[0074] Downstream of the turbine 6 , the carbon dioxide separation unit 88 separates carbon dioxide from the exhaust gas and stores the separated carbon dioxide in the carbon dioxide storage unit 80 .

[0075] In an embodiment, the carbon dioxide separation unit 88 dries the exhaust gas, compresses the exhaust gas, and then transfers the exhaust gas to one or more refrigeration circuits, and then performs an expansion process to liquefy or solidify the carbon dioxide in the exhaust gas, and then separates the carbon dioxide from the liquid or solid exhaust gas, and stores the separated carbon dioxide in liquid or solid form in the carbon dioxide storage unit 80.

[0076] In another embodiment (not shown in the drawings), the carbon dioxide separation unit 88 uses a carbon dioxide absorber (e.g., using an absorber solvent) that is operably connected to a regenerator, such as an amine regenerator, to separate carbon dioxide from the exhaust gas. The regenerator can use steam to strip CO2 from the absorbent.

[0077] Various aspects and embodiments are described herein in conjunction with various embodiments. These embodiments may be combined in various ways. In addition, other variations of the disclosed embodiments may be understood and implemented by a person skilled in the art of practicing the claimed subject matter by studying the drawings, the disclosure and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "one" or "a" does not exclude the plural. A single processor, controller or other unit may implement the functions of several items described in the claims. The mere fact that certain measures are listed in mutually different dependent claims does not indicate that the combination of these claims measured cannot be used to advantage. The reference numerals used in the claims should not be interpreted as limiting the scope.

Claims

1. A large two-stroke turbocharged single-flow scavenged internal combustion engine with a crosshead, the engine comprising: A plurality of combustion chambers, each of which is bounded by a cylinder liner (1), a piston (10) and a cylinder cover (22), wherein the piston (10) is configured to reciprocate in the cylinder liner (1), a scavenging port (18) arranged in the cylinder liner (1) for allowing scavenging gas to enter the combustion chamber, an exhaust outlet, which is arranged in the cylinder cover (22) and which is controlled by an exhaust valve (4), a fuel system configured to supply a carbon-based fuel to the combustion chamber, The combustion chamber is configured to burn the carbon-based fuel to generate combustion gas containing carbon dioxide, The combustion chamber is connected to a scavenging air receiver (2) via the scavenging air port (18), and the combustion chamber is connected to a combustion gas receiver (3) via the exhaust gas outlet, an exhaust gas recirculation system (60) configured to recirculate a portion of the combustion gases from the combustion chamber to the scavenging air receiver (2), the exhaust gas recirculation system (60) comprising a blower (75) for assisting the flow of the combustion gases to the scavenging air receiver (2), an exhaust system configured to discharge another portion of the combustion gases from the combustion chamber as exhaust gas, The exhaust system comprises a turbine (6) of a turbocharger system (5) driven by the exhaust gas, an air inlet system, the air inlet system comprising a compressor (7) of the turbocharger system (5), the compressor (7) being configured to supply pressurized scavenging air to the scavenging air receiver (2), The exhaust system comprises a carbon dioxide separation system and a carbon dioxide storage unit (80), wherein the carbon dioxide storage unit (80) is connected to an outlet of the carbon dioxide separation system, and The carbon dioxide separation system is configured to: receive exhaust gas; separate at least a portion of carbon dioxide in the exhaust gas from the exhaust gas; and transmit the separated carbon dioxide to the carbon dioxide storage unit (80).

2. The engine according to claim 1, wherein: The carbon dioxide separation system is configured to separate at least a portion of the carbon dioxide in the exhaust gas from the exhaust gas by liquefying and / or solidifying the carbon dioxide.

3. The engine of claim 1, comprising a controller (40) configured to adjust a mass percentage of recirculated combustion gas in the scavenging gas to at least 40%.

4. The engine of claim 1, comprising a controller (40) configured to adjust the mass percentage of recirculated combustion gas in the scavenging gas to between 40% and 55%.

5. The engine according to claim 3, wherein: The controller (40) is configured to control the speed of the blower (75) to adjust the percentage of recirculated combustion gas in the purge gas.

6. The engine according to claim 1, comprising a cooler (65) of the combustion gases to water.

7. The engine according to claim 6, wherein: The combustion gas to water cooler (65) is arranged upstream of the point at which the flow of combustion gases from the engine is divided into a portion to be recirculated and another portion to be discharged.

8. The engine according to claim 1, comprising a heat exchanger (66) of combustion gases relative to a cooling medium and a cooling facility (68), the cooling facility (68) being configured to circulate the cooling medium through the heat exchanger (66) of combustion gases relative to a cooling medium.

9. The engine according to claim 8, wherein: The combustion gas relative to cooling medium heat exchanger (66) is arranged downstream of the point at which the flow of combustion gases from the engine is divided into a portion to be recirculated and another portion to be discharged.

10. The engine according to claim 1, comprising a cooler (69) located downstream of the turbine (6), the cooler (69) being used to cool the exhaust gas so as to liquefy and / or solidify carbon dioxide in the exhaust gas.

11. The engine according to claim 3 or 4, wherein: The controller (40) is configured to control the operation of the engine so that the temperature of the exhaust gas is -82 degrees Celsius or lower when the exhaust gas reaches atmospheric pressure downstream of the turbine (6).

12. The engine according to claim 1, wherein: The turbine (6) is mechanically coupled to the compressor (7) and drives the compressor (7).

13. The engine according to claim 1, wherein: The turbine (6) drives the compressor (7) with the assistance of an electric drive motor (77).

14. The engine according to claim 1, wherein: The compressor (7) is driven by an electric drive motor (78), and wherein the turbine (6) drives a generator or alternator (79).

15. A method of operating a large two-stroke turbocharged uniflow scavenged internal combustion engine having a plurality of combustion chambers, the method comprising: supplying a carbon-based fuel to the combustion chamber, causing the carbon-based fuel to burn in the combustion chamber to generate combustion gas containing carbon dioxide, recirculating a portion of the combustion gas through an exhaust gas recirculation system and exhausting another portion of the combustion gas as exhaust gas through an exhaust system, supplying the combustion chamber with pressurized purge gas, the pressurized purge gas containing at least 40% by mass of recirculated combustion gas, separating carbon dioxide from the exhaust gas in a carbon dioxide separation process, and The separated carbon dioxide is stored in a carbon dioxide storage unit (80).

16. A method according to claim 15, comprising subjecting the exhaust gases to one or more cooling and expansion processes in order to liquefy and / or solidify the carbon dioxide downstream of a turbine (6) of the exhaust system.

17. The method according to claim 16, comprising storing the carbon dioxide in the carbon dioxide storage unit (80) in liquid or solid form.

18. The method of claim 15, comprising controlling the speed of a blower (75) in the exhaust gas recirculation system to adjust the percentage of recirculated combustion gases in the pressurized scavenging gas.

19. The method according to claim 16, wherein: At least part of the expansion process is carried out in the turbine (6).

20. The method according to claim 15, wherein: The engine comprises a combustion gas to water cooler (65), wherein the method comprises cooling the combustion gas to a temperature below 40 degrees Celsius using the combustion gas to water cooler (65).

21. The method according to claim 20, wherein: The combustion gas to water cooler (65) is arranged upstream of the point at which the flow of combustion gases from the engine is divided into a portion to be recirculated and a portion to be discharged.

22. The method according to claim 15, wherein: The engine comprises a heat exchanger (66) of combustion gases to a cooling medium and a cooling facility (68) configured to recirculate the cooling medium through the heat exchanger (66) of combustion gases to a cooling medium to cool the combustion gases to a temperature below -10 degrees Celsius.

23. The method according to claim 22, wherein: The heat exchanger (66) for the combustion gases relative to the cooling medium is arranged downstream of the point at which the flow of combustion gases from the engine is divided into a portion to be recirculated and a portion to be discharged.

24. The method according to claim 16, wherein: The engine comprises a cooler (69) downstream of the turbine (6) for additionally cooling the exhaust gas for liquefying and / or solidifying carbon dioxide in the exhaust gas.

25. The method according to claim 24, comprising: The exhaust gas is cooled to a temperature of -80 degrees Celsius or below at atmospheric pressure for liquefying and / or solidifying carbon dioxide in the exhaust gas.

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