JP2023124826A - Method for recovering carbon dioxide and large 2-stroke uniflow scavenging internal combustion engine - Google Patents

Abstract

To separate and recover carbon dioxide from exhaust gas in a large 2-stroke turbocharging type uniflow scavenging internal combustion engine.SOLUTION: A method for recovering carbon dioxide includes: supplying carbon-based fuel to a combustion chamber; burning the carbon-based fuel in the combustion chamber to generate combustion gas containing carbon dioxide; recirculating part of the combustion gas and discharging the other part as exhaust gas; supplying pressurized scavenging gas containing at least 40 mass% of, preferably 40-55 mass% of recirculation combustion gas to the combustion chamber; separating carbon dioxide from exhaust gas in a carbon dioxide separation process; and storing the separated carbon dioxide in a storage unit (80).SELECTED DRAWING: Figure 3

Description

The present disclosure relates to large two-stroke internal combustion engines, particularly crosshead large two-stroke uniflow scavenging internal combustion engines operating on carbonaceous fuels (gaseous or liquid), and to reduce carbon dioxide emissions. on how to operate this type of engine.

background

A large two-stroke uniflow scavenging internal combustion engine of a crosshead type is used, for example, as a propulsion system for a large ship or as a prime mover of a power plant. The size of this large two-stroke diesel engine is huge. Not only because of its enormous size, this large two-stroke diesel engine has a different construction than other internal combustion engines. For example, the weight of the exhaust valve can reach 400 kg and the diameter of the piston can reach 100 cm. The maximum pressure in the combustion chamber during operation is typically several hundred bars. The forces generated by such high pressure levels and piston sizes are enormous.

Large two-stroke turbo internal combustion engines can run on liquid fuels (e.g. fuel oil, marine diesel, heavy oil, ethanol, dimethyl ether (DME)) or gas fuels (e.g. natural gas (LNG), petroleum gas (LPG), methanol or ethane). ).

Engines operating on gas fuel may operate according to the Otto cycle. In the Otto cycle, gas fuel is introduced from a fuel valve located near the longitudinal center of the cylinder liner or on the cylinder cover. In this type of engine, gas fuel is introduced into the cylinder during the upward stroke of the piston (from bottom dead center to top dead center) and well before the exhaust valve closes. The engine compresses a mixture of gaseous fuel and scavenging air in the combustion chamber, timing the compressed mixture at or near top dead center (TDC) by ignition means (such as liquid fuel injection). to ignite.

Liquid-fueled engines and high-pressure injection gas-fueled engines inject gas or liquid fuel when the piston is close to TDC, i.e., when the compression pressure in the combustion chamber is at or near maximum. . These engines are thus operated on the diesel cycle, ie compression ignition.

The liquid and gas fuels used in known large two-stroke turbocharged uniflow scavenging internal combustion engines generally contain carbon. That is, they are carbon-based fuels, the combustion of which produces carbon dioxide. The carbon dioxide produced is discharged into the atmosphere. Carbon dioxide emissions are generally considered detrimental to the environment and should be minimized or avoided.

KR20180072552 discloses a large two-stroke turbocharged uniflow scavenging internal combustion engine with multiple cylinders. In this engine, the cylinder includes a scavenging port, a scavenging valve, an exhaust gas storage unit connected to the cylinder via an individual exhaust valve, a turbocharger, an outlet of the exhaust gas storage unit and the turbocharger. a compressor of the turbocharger driven by the turbine; and a scavenging duct connecting the outlet of the compressor and the inlet of the scavenging air container. The scavenging air conduit 11 has a scavenging air cooler and the scavenging air reservoir is connected to the cylinder via individual scavenging air ports. The engine further comprises an exhaust gas recirculation conduit for recirculating a portion of the exhaust gas to the cylinders, the recirculation conduit comprising a blower or compressor for forcing the recirculated exhaust gases back to the cylinders and scavenge air cooling. a cylinder bypass pipe for transporting a portion of the hot scavenging air from the scavenging air conduit upstream of the vessel to the turbine of the turbocharger to bypass the cylinder; and a boiler. The engine is configured to transport at least a first portion of exhaust gas from the cylinders through the boiler.

Summary

It is an object to provide an engine and method that solves or at least mitigates the above-mentioned problems.

The above-mentioned and other problems are solved by the features of the independent claims. More specific implementations will become apparent from the dependent claims, the detailed description of the invention and the drawings.

According to a first way of thinking, there is provided a crosshead type large two-stroke turbocharged uniflow scavenging internal combustion engine as follows. This institution
a plurality of combustion chambers each defined by a cylinder liner, a piston configured to reciprocate within the cylinder liner, and a cylinder cover;
a scavenging port for introducing scavenging gas into the combustion chamber, the scavenging port disposed in the cylinder liner;
an exhaust gas outlet located in the cylinder cover and controlled by an exhaust valve;
a fuel system configured to supply carbon-based fuel to the combustion chamber;
with
The combustion chamber is configured to burn the carbon-based fuel and generate a combustion gas containing carbon dioxide,
the combustion chamber is connected to a scavenging receiver via the scavenging port and connected to a combustion gas receiver via the exhaust gas outlet;
the engine further comprising an exhaust gas recirculation system configured to recirculate a portion of combustion gases discharged from the combustion chamber to the scavenge receiver;
said exhaust gas recirculation system having a blower for assisting the flow of combustion gases to said scavenge receiver;
The engine further comprises an exhaust system configured to exhaust another portion of combustion gases generated from the combustion chamber as exhaust gas,
The exhaust system has a turbine of a turbocharging system and is driven by the exhaust gas,
the engine further comprising an air intake system having a compressor of the turbocharging system, the compressor configured to supply pressurized scavenging air to the scavenging receiver;
The exhaust system has a carbon dioxide separator and a carbon dioxide storage system connected to an outlet of the carbon dioxide separator,
The carbon dioxide separation device receives an exhaust gas and separates at least a portion of the carbon dioxide in the exhaust gas, preferably by solidifying and/or liquefying the carbon dioxide, from the exhaust gas to produce the separated carbon dioxide. configured to deliver to said carbon dioxide storage unit.

By operating the engine with combustion gas recirculation, the concentration of carbon dioxide in the exhaust gas is increased and the separation of carbon dioxide from the exhaust gas can be performed more effectively. Also, by separating the carbon dioxide from the exhaust gas and storing the carbon dioxide, the carbon dioxide emissions of the engine can be reduced.

In an example of implementation of said first aspect, said engine comprises a control unit adapted to adjust the mass proportion of recirculated combustion gases in the scavenging gas to at least 40%, preferably from 40% to 55%. Prepare.

In one example of implementation of the first aspect, the controller is configured to control the speed of rotation of the blower to adjust the proportion of recirculated combustion gases in the scavenging gas.

In an example of implementation of the first aspect, the engine has a combustion gas-water cooler, preferably a combustion gas-seawater cooler, and the combustion gas-water cooler is preferably a It is located upstream of the location where the flow of combustion gases is divided into a recirculated portion and another exhausted portion.

In an example of implementation of said first aspect, said engine comprises a combustion gas-coolant heat exchanger and a cooling facility, said cooling facility passing a cooling medium through said combustion gas-coolant heat exchanger. is configured to circulate the Said combustion gas-medium heat exchanger is preferably located downstream of a location where the flow of combustion gases from said engine is divided into a recirculated portion and another exhausted portion.

In an example implementation of the first aspect, the combustion gas-coolant heat exchanger is connected to the cooling facility.

In one example of implementation of the first aspect, the engine comprises, downstream of the turbine, a cooler for cooling the exhaust gas in order to solidify the carbon dioxide in the exhaust gas.

In an example of implementation of the first aspect, the cooler is connected to the cooling facility.

In one example of the implementation of the first approach, the control unit controls the operation of the engine so that the temperature of the exhaust gas is −82° C. or less when atmospheric pressure is reached downstream of the turbine. and configured to solidify carbon dioxide in the exhaust gas.

In an example implementation of the first aspect, the turbine is mechanically coupled to drive the compressor. Said compressor is preferably assisted by an electric drive motor. There are operating conditions in which the turbine does not provide enough energy to operate the compressor in order for the turbine to provide sufficient expansion to the exhaust gases and thereby sufficient cooling. These operating conditions require additional energy to be added to the turbocharging system by the electric drive motor.

In one example of implementation of the first aspect, the compressor is driven by an electric drive motor and the turbine drives an electric generator or alternator. In this setup of the turbocharging system, the additional energy that may be required by the turbocharging system may be in the form of an electric generator or alternator driven by said engine, either by an electric drive motor driving the compressor, or externally. power source, or by a generator set associated with said engine.

In an example implementation of the first concept, the engine is operated according to the Otto cycle and gas fuel is supplied from the fuel valve during the stroke of the piston from bottom dead center (BDC) to top dead center (TDC). introduced into the combustion chamber.

In one example of implementation of the first concept, the engine is operated in a diesel cycle and gas or liquid fuel is injected from a fuel valve into the combustion chamber when the piston is nearing top dead center (TDC). be done.

According to a second conception, there is provided a method of operating a large two-stroke turbocharged uniflow scavenging internal combustion engine having multiple combustion chambers, as follows. This method
supplying a carbonaceous fuel to the combustion chamber;
burning the carbon-based fuel in the combustion chamber to generate a combustion gas containing carbon dioxide;
recirculating a portion of the combustion gases and discharging another portion of the combustion gases as an exhaust gas;
supplying pressurized scavenging gas to said combustion chamber comprising at least 40% by mass, preferably 40 to 55% by mass of recirculated combustion gas;
separating carbon dioxide from the exhaust gas in a carbon dioxide separation process;
storing the separated carbon dioxide in a storage unit;
including.

By operating the engine at a high combustion gas recirculation ratio, the concentration of carbon dioxide in the exhaust gas can be increased and the separation of carbon dioxide from the exhaust gas can be facilitated. Also, by separating the carbon dioxide from the exhaust gas and storing the carbon dioxide, the emissions of carbon dioxide by the engine can be avoided or at least reduced.

In one example of implementation of the second aspect, the method includes solidifying (freezing) at least a portion of the carbon dioxide in the exhaust gas. Freezing the carbon dioxide makes it relatively easy to separate it from other components in the exhaust gas. Storing carbon dioxide in solidified form can be done in a container that does not take up space and does not need to be pressurized.

In one example implementation of the second aspect, the method includes subjecting the exhaust gas to one or more cooling and expansion processes, thereby solidifying and/or liquefying carbon dioxide downstream of the turbine.

In one example of implementation of the second aspect, the method includes storing carbon dioxide in liquid or solid form in a storage unit.

In one example implementation of the second aspect, the method comprises controlling the speed of a blower of an exhaust recirculation system to adjust the proportion of recirculated combustion gases in the pressurized scavenging gas. include.

In one example of implementation of said second aspect, at least part of the expansion process takes place in a turbine.

In an example of implementation of the second aspect, the engine has a combustion gas-water cooler, preferably an exhaust gas-seawater cooler, and the combustion gas-water cooler is preferably a combustion gas from the engine. It is located upstream of the location where the gas flow is split between the recirculated part and the other vented part. The method then includes cooling the combustion gas with the combustion gas-water cooler, preferably to a temperature of 40°C or less, more preferably 31°C or less.

In an example of implementation of the second aspect, the engine comprises an exhaust gas-coolant heat exchanger and a cooling facility, the cooling facility passing a cooling medium through the exhaust gas-coolant heat exchanger. is preferably circulated to a temperature of -10°C or lower, more preferably -15°C or lower.

In one example of implementation of the second concept, the solidified water (ice) in the exhaust gas is separated from the exhaust gas by a method such as gravity separation or centrifugation and stored or discarded.

In an example of implementation of the second aspect, the engine further feeds the exhaust gas downstream of the turbine (preferably to a temperature of -80°C or below at atmospheric pressure) to solidify the carbon dioxide in the exhaust gas. Equipped with a cooler for cooling.

In one example of implementation of the second aspect, the method includes compressing air with a compressor and mixing combustion gas and compressed air to obtain scavenging gas.

In one example of an implementation of the second aspect, the method includes compressing the recycled combustion gas with a blower compressor prior to mixing the combustion gas and compressed air.

These and other aspects will become more apparent from the examples described below.

Hereinafter, various concepts, embodiments, and implementation examples will be described in detail with reference to exemplary embodiments shown in the drawings.
1 is a front view of a large two-stroke diesel engine in accordance with certain exemplary embodiments; FIG. 2 is a side view of the large two-stroke engine of FIG. 1; FIG. 2 is a schematic representation of the large two-stroke engine of FIG. 1, according to certain embodiments; 2 is a schematic representation of the large two-stroke engine of FIG. 1 according to another embodiment; 2 is a schematic representation of the large two-stroke engine of FIG. 1 according to yet another embodiment;

Detailed explanation

In the following detailed description, the internal combustion engine will be described with reference to the crosshead type large low speed two-stroke turbocharged internal combustion engine of the embodiment. 1-3 depict an example of a turbocharged large low speed two-stroke diesel engine. This engine has a crankshaft 8 and a crosshead 9 . 1 is a front view, and FIG. 2 is a side view. FIG. 3 is a schematic representation of the turbocharged large low speed two-stroke diesel engine of FIGS. 1 and 2 along with its intake and exhaust systems, according to an embodiment. In this example, the engine has four cylinders in series. A turbocharged large low speed two-stroke internal combustion engine may have from 4 to 14 cylinders arranged in series. These cylinders have cylinder liners carried on the engine frame 11 . Such an engine can also be used, for example, as a main engine on ships or as a stationary engine for powering generators in power plants. The total engine power can be, for example, from 1000 kW to 110000 kW.

The engine in this example is a two-stroke uniflow scavenging engine, in which a scavenging port 18 is provided in the lower region of the cylinder liner 1 . A central exhaust valve 4 is arranged on a cylinder cover 22 above the cylinder liner 1 . Scavenging gas is directed from the scavenging receiver 2 to the scavenging port 18 of each cylinder liner 1 when the piston is below the scavenging port 18 . Gas fuel (e.g. methanol, petroleum gas or LPG, natural gas LNG, or ethane) is electronically controlled before the piston passes fuel valve 30 (gas inlet valve) during its upward movement (BDC to TDC). 60 and/or liquid fuel (e.g. fuel oil) is injected from the liquid fuel valve 50 at high pressure (preferably above 300 bar) when the piston 10 is at or near TDC. be done. In the former case the gaseous fuel is introduced at a relatively low pressure, less than 30 bar, preferably less than 25 bar, more preferably less than 20 bar. The fuel valves 30 are preferably evenly distributed around the circumference of the cylinder liner. Also preferably, it is arranged near the center in the longitudinal direction of the cylinder liner. Introduction of the gaseous fuel occurs when the compression pressure is relatively low. That is, it can be introduced at a relatively low pressure, since it is done at a much lower compression pressure than the piston reaches TDC. .

A piston 10 in the cylinder liner 1 compresses a mixture of gaseous fuel and scavenging gas (compressing scavenging gas for operation with liquid fuel injection only at TDC). Ignition is then induced at or near TDC by injection of high pressure liquid fuel from a liquid fuel valve 50 preferably located in the cylinder cover 22 . With only liquid fuel injection at or near TDC, compression causes ignition. Combustion then occurs, producing combustion gases containing carbon dioxide.

When the exhaust valve 4 is opened, the combustion gases flow through the combustion gas duct associated with the cylinder 1 into the combustion gas receiver 3 and onwards via the combustion gas conduit 19 including the combustion gas-water cooler 65 . The combustion gas-water cooler 65 operates on sea water when the engine is installed on board a ship. The activity of the flue gas-water cooler 65 is controlled by the controller 40 to reduce the flue gas from a temperature of 425 to 475° C. at the inlet of the flue gas-water cooler 65 to less than 40° C. at the outlet of the flue gas-water cooler 65, Cooling is preferably controlled to a temperature below 35°C, most preferably below 31°C. Preferably, at a location downstream of the combustion gases to the water cooler 65, the flow of combustion gases is split into a portion that flows to the combustion gas recirculation system 60 and another portion that flows to the exhaust system. The combustion gas recirculation system 60 connects to the scavenging system, as further described below. The combustion gas recirculation system 60 has conduits that connect to the scavenging system and may have a (preferably water-operated) scrubber 70 for scrubbing the combustion gases. The combustion gas recirculation system 60 also includes a blower 75 for forcing the combustion gases through the combustion gas system 60 to the scavenging system. Blower 75 is preferably driven by an electric drive motor 76 . The operation of the blower 75 is controlled by the controller 40 . In some embodiments, the controller 40 adjusts the combustion gas ratio (mass ratio) in the scavenging gas by adjusting the operation of the blower 75 . Depending on the embodiment, the control unit 40 is configured to adjust the combustion gas ratio (mass ratio) in the scavenging gas to 40% or more, preferably 45% or more, and most preferably 40 to 55%. %. The combustion gas ratio is the ratio of the combustion gas mass to the total gas mass introduced into the engine.

The exhaust system has an exhaust conduit 63 . The exhaust conduit 63 has an exhaust gas-coolant heat exchanger 66 and leads to the turbine 6 of the turbocharger 5 . The exhaust gas-coolant heat exchanger 66 is connected to a cooling facility 68 . The cooling facility 60 circulates the cooling medium through the combustion gas-to-cooling medium heat exchanger 68 to cool the exhaust gas to a temperature below -10°C, more preferably below -15°C at the outlet of the cooling medium heat exchanger 66. is configured to This causes the moisture in the exhaust gas to solidify (become ice or snow) and be separated by gravity or centrifugation and removed through the drain 64 . The cooling medium (refrigerant) may have a temperature in the range of -20 to -30°C at the cooling medium inlet of the cooling medium heat exchanger 66 . Suitable cooling media (refrigerants) are, for example, ammonia, propane, isobutane, carbon dioxide and other known cooling media for industrial cooling installations. The operation of the cooling medium heat exchanger 66 is controlled by the control unit 40 so that the temperature of the exhaust gas at the outlet of the cooling medium heat exchanger 66 reaches a desired temperature.

From the outlet of the coolant heat exchanger 66 the exhaust gases flow to the inlet of the turbine 6 . At the outlet of the turbine 6, the exhaust gas has been expanded in the turbine 6 to reduce its temperature to -80°C or lower (preferably -82°C or lower) at ambient pressure (atmospheric pressure). Under such conditions, the carbon dioxide in the exhaust gas solidifies (freezes). Solidified carbon dioxide is separated by, for example, a gravity or centrifugal separation process. The separated solid carbon dioxide is stored in storage unit 80 . The remaining exhaust gas contains no carbon dioxide or only a small amount of carbon dioxide and is discharged into the atmosphere through outlet 21 .

In this embodiment, the engine has a cooler 69 downstream of the turbine 6 to further cool the exhaust gas in order to solidify the carbon dioxide in the exhaust gas. Cooler 69 cools the exhaust gas to a temperature preferably below -80°C at atmospheric pressure. In this embodiment, solid carbon dioxide is separated in cooler 69, at the outlet of cooler 69, or immediately downstream of cooler 69, for example by a gravity or centrifugal process. The separated solid carbon dioxide is stored in the carbon dioxide unit 80 . Carbon dioxide stored in carbon dioxide storage unit 80 can then be stored in a more permanent means for storing separated carbon dioxide.

Turbine 6 drives compressor 7 via a shaft. Outside air is supplied to the compressor 9 through an air intake 12 . The turbocharger 5 is assisted by an electric drive motor 77 if the turbine 6 does not provide sufficient power to drive the compressor 7 .

The compressor 7 sends the compressed scavenging air to the scavenging pipe 13 connected to the scavenging receiver 2 . The scavenging air in the scavenging pipe 13 passes through an intercooler 14 for cooling the scavenging air.

Either upstream (shown) or downstream (not shown) of intercooler 14, combustion gas recirculation system 60 is connected to scavenge air conduit 13. The recirculated combustion gases are mixed with scavenging air at this location to form scavenging gas. The controller 40 is configured such that the scavenging gas contains 40-55% by mass of combustion gas.

The cooled scavenging air or gas passes through an auxiliary blower 16 driven by an electric motor 17 . The auxiliary blower 16 compresses the scavenging air flow when the compressor 7 of the turbocharger 5 cannot provide sufficient pressure for the scavenging receiver 2, ie when the engine is under low or part load. At high engine loads, the turbocharger compressor 7 can supply sufficiently compressed scavenging air so that the auxiliary blower 16 is bypassed by the non-return valve 15 .

The controller 40 (electronic control unit) may consist of a plurality of interconnected electronic units comprising processors and other hardware for performing the functions of the controller. The control section 40 generally controls the operation of the engine, such as gas fuel introduction (amount and timing), liquid fuel injection (amount and timing), opening and closing of the exhaust valve 4 (timing and lift amount), recirculated combustion gas ratio, and It unifies the control over the operation of various coolers. Here, the controller 40 is adapted to receive various signals from sensors that indicate the operating state of the engine. These signals may include signals representing engine load, engine speed, blower speed, scavenge air temperature, combustion gas temperature at various locations, exhaust gas temperature at various locations, respectively. Signals indicative of scavenge system pressure, combustion chamber pressure, exhaust gas system pressure, and combustion gas recirculation system pressure may also be included. The engine preferably includes a variable timing exhaust valve actuation system that allows individual control of exhaust valve timing for each combustion chamber. The controller 40 is connected to the fuel valve 30, liquid fuel valve 50, exhaust valve actuators, angular position sensors and pressure sensors via signal lines or wireless connections. An angular position sensor detects the angle of the crankshaft and produces a signal representative of the position of the crankshaft. A pressure sensor is preferably located in the cylinder cover 22, alternatively in the cylinder liner 1, and produces a signal representative of the pressure in the combustion chamber.

Depending on the size of the engine, the cylinder liner 1 is made in various sizes. Typical dimensions are cylinder bore diameters of 250 mm to 1000 mm and corresponding overall lengths of 1000 mm to 4500 mm.

The cylinder liner 1 is placed on the cylinder frame 23 and the cylinder cover 22 is installed on the cylinder liner 1 . The cylinder liner 1 and the cylinder cover 22 are arranged so that gas does not leak therebetween. Piston 10 is configured to reciprocate between bottom dead center (BDC) and top dead center (TDC). These two positions are 180 degrees apart in rotation angle of the crankshaft 8 . The cylinder liner 1 is provided with a plurality of cylinder lubrication holes distributed in the circumferential direction. These cylinder lubrication holes are connected to cylinder lubrication lines. The cylinder lubrication line supplies cylinder lubrication oil as the piston 10 passes through the cylinder lubrication hole 25 . Piston rings (not shown) of the piston 10 then distribute the cylinder lubricating oil over the entire running surface (inner surface) of the cylinder liner.

A plurality, preferably three or four, of liquid fuel valves 50 are typically mounted on the cylinder cover 22 and connected to a supply of liquid fuel (not shown). The liquid fuel valve 50 is preferably positioned around the exhaust valve 4 , in particular around the central outlet (opening) of the cylinder cover 22 (controlled by the exhaust valve 4 ). The injection timing and injection amount of the liquid fuel are controlled by the controller 40 . Liquid fuel valve 50 is only used to inject a small amount of ignition fluid (pilot) when the engine is operating in gas fuel mode. When the engine is operating in the liquid fuel mode, the liquid fuel valve 50 injects the necessary amount of liquid fuel to operate the engine at the actual engine load. The cylinder cover 22 may be provided with a pre-chamber (not shown). Also, the tip of the liquid fuel valve 50, typically the tip provided with a nozzle having one or more nozzle holes, is arranged so that the pilot oil (ignition liquid) is injected into the front chamber and atomized. It is The vestibule supports reliable ignition. In some embodiments, the vestibule is a double vestibule, ie two vestibules connected in series.

A fuel valve 30 is mounted on the cylinder liner 1 (or the cylinder cover 22). The fuel valve 30 has a nozzle that lies substantially flush with the inner surface of the cylinder liner 1 . Also, the rear end of the fuel valve 30 protrudes from the outer wall of the cylinder liner 1 . Typically, each cylinder liner 1 has one, two, and possibly as many as three or four fuel valves 30 distributed circumferentially around the cylinder liner 1 (preferably equally spaced circumferentially). ) are distributed. In this embodiment, the fuel valve 30 is arranged exactly in the center of the cylinder liner 1 in the longitudinal direction. Fuel valve 30 is connected to a pressurized source of gaseous fuel 40 (eg, methanol, LPG, LNG, ethane, or ammonia). That is, the fuel is in the gaseous phase when it is supplied to fuel valve 30 . Since the gas fuel is introduced during the stroke of the piston 10 from BDC to TDC, the pressure of the source of gas fuel need only be higher than the pressure existing in the cylinder liner 1 . Typically, a pressure of less than 20 bar is sufficient for gas fuel delivered to fuel valve 30 . Fuel valve 30 is connected to control unit 40 . The control unit 40 determines the opening/closing timing and valve opening time of the fuel valve 30 .

In some embodiments, the liquid fuel for ignition is heavy oil, marine diesel, heavy oil, ethanol, or dimethyl ether (DME).

The gas mode of operation can be one of several modes of operation of the engine. Other modes may include a liquid fuel operating mode in which all of the fuel required for engine operation is supplied in liquid form through liquid fuel valve 50 . In the gas-fueled mode of operation, the engine is primarily operated on gas fuel introduced at relatively low pressure during the BDC to TDC piston stroke. That is, a major portion of the energy supplied to the engine is supplied by such gas fuel. On the other hand, compared to gas fuels, liquid fuels are used in small quantities and make a relatively small contribution to the amount of energy supplied to the engine. The purpose of liquid fuel is to ignite at a predetermined timing. That is, the liquid fuel functions as an ignition fluid.

Thus, the engine of this embodiment can be a dual fuel engine, having a mode of operation on liquid fuel only and a mode of operation on substantially gas fuel only.

The operation of the engine is to supply a carbonaceous fuel (liquid fuel and/or gaseous fuel) to a combustion chamber; and to burn said carbonaceous fuel in said combustion chamber to produce combustion gases comprising carbon dioxide. recirculating a portion of said combustion gases and discharging another portion of said combustion gases as exhaust gas; supplying the scavenged gas to the combustion chamber; separating carbon dioxide from the exhaust gas in a carbon dioxide separation process; storing the separated carbon dioxide in a storage unit 80;
including.

In this process, the exhaust gas undergoes a cooling and expansion process and the carbon dioxide in the exhaust gas solidifies (freezes) at the outlet of the turbine 6 or in a cooler 69 downstream of the turbine 6 . The frozen carbon dioxide is separated, for example by a gravity separation process or a centrifugation process, and then stored in the storage unit 80 in a solid state. In some embodiments, storage unit 80 is a thermally insulated, non-pressurized vessel or tank.

Control 40 controls the speed of blower 75 of exhaust recirculation system 60 to regulate the proportion of recirculated combustion gases in the pressurized scavenging gas. A proportion of 40% by weight is preferably adjusted. This is to increase the concentration of carbon dioxide in the combustion gas. In some embodiments, the controller 40 is configured to adjust the recirculated flue gas ratio to at least double the carbon dioxide concentration in the flue gas as compared to operating without flue gas recirculation. be done.

At least part of the exhaust gas expansion process takes place in the turbine 6 . This expansion process causes the temperature and pressure of the exhaust gas to drop significantly, preferably below -82°C at atmospheric pressure. The carbon dioxide in the exhaust gas is thereby solidified.

Figure 4 shows another embodiment of the engine. In this embodiment, structures and features that are similar to structures and features already described or illustrated are labeled with the same reference numerals used previously. The engine of this embodiment and its operation are substantially the same as the previous embodiment, so only the differences from the previous embodiment will be described in detail.

In this embodiment the compressor 7 is driven by an electric drive motor 78 . Turbine 6 drives an electric generator or alternator 79 . In this setup of the turbocharging system, the additional energy that may be required by the turbocharging system is supplied by the electric drive motor 78 that drives the compressor 7 . Here the electric drive motor 78 is powered by a power source, which may be in the form of an electric generator or alternator driven by the engine. The electric drive motor 78 may also be powered by a power generation system on board the engine.

In this embodiment, the engine is shown as a compression ignition engine (operating according to the diesel principle) and carbonaceous fuel (gas or liquid) is injected at high pressure when the piston 10 is at or near TDC. . The illustrated engine does not require a prechamber in the cylinder liner 10 nor a fuel inlet valve 30 . However, the engine according to this embodiment can also be operated according to the Otto principle of introducing gaseous fuel during the stroke of the piston 10 from BDC to TDC.

In this embodiment, the control unit 40 determines 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 to be separated at the outlet of the turbine 6 by gravity separation or centrifugal separation. The engine is configured to operate for separate storage in the carbon dioxide storage unit 80 .

Figure 5 shows another embodiment of the engine. In this embodiment, structures and features that are similar to structures and features already described or illustrated are labeled with the same reference numerals used previously. The engine of this embodiment and its operation are substantially the same as the previous embodiment, so only the differences from the previous embodiment will be described in detail.

Although in this embodiment the engine is shown as a gas introduction engine operating according to the Otto principle, it should be understood that this embodiment could equally work with a high pressure fuel injection engine operating according to the Diesel principle.

In this embodiment, no measures are taken to make the temperature of the exhaust gas at the outlet of the turbine 6 lower than usual. Therefore, no flue gas-water cooler is required, nor is an exhaust gas-coolant cooler connected to the cooling installation. Therefore, the temperature of the exhaust gas is conventional and ranges from 180°C to 250°C.

Downstream of turbine 6 , a carbon dioxide separation unit 88 separates carbon dioxide from the exhaust gas and stores the separated carbon dioxide in carbon dioxide container 80 .

In this embodiment, the carbon dioxide separation unit 88 dries the flue gas, compresses the flue gas, and then subjects the flue gas to one or more cooling loops to perform an expansion process that liquefies or solidifies the carbon dioxide in the flue gas; The liquid or solid exhaust carbon dioxide is then separated and stored in a liquid or solid carbon dioxide storage unit 80 .

In another embodiment (not shown in the drawings), carbon dioxide separation unit 88 uses a carbon dioxide absorber (eg, using an absorbent solvent) to separate carbon dioxide from the flue gas. The carbon dioxide separation unit 88 is operably connected to a regenerator, such as an amine regenerator. The regenerator may use steam to remove carbon dioxide from the absorbent solvent.

Various aspects and implementations of the invention have been described with several examples. The above embodiments can be combined in various ways. In addition, there are many variations in addition to the illustrated embodiments in carrying out the claimed invention that a person skilled in the art, upon reviewing the specification, drawings, and claims of this application, will appreciate. understand and be able to implement it. The verbs "comprising," "having," and "including" in the claims do not exclude the presence of elements or steps not recited. The absence of an explicit plural number of an element in a claim does not exclude the presence of a plurality of such elements. The functions of several elements recited in the claims may be performed by a single processor, controller or other unit. The mere fact that certain items are recited in separate dependent claims does not preclude their joint practice, which may be practiced to advantage. Any reference signs used in the claims shall not be construed as limiting the scope of the invention.

Claims (17)

A crosshead type large two-stroke turbocharged uniflow scavenging internal combustion engine,
a plurality of combustion chambers each defined by a cylinder liner, a piston configured to reciprocate within the cylinder liner, and a cylinder cover;
a scavenging port for introducing scavenging gas into the combustion chamber, the scavenging port disposed in the cylinder liner;
an exhaust outlet located in the cylinder cover and controlled by an exhaust valve;
a fuel system configured to supply carbon-based fuel to the combustion chamber;
with
The combustion chamber is configured to burn the carbon-based fuel and generate a combustion gas containing carbon dioxide,
the combustion chamber is connected to a scavenging receiver via the scavenging port and connected to a combustion gas receiver via the exhaust gas outlet;
the engine further comprising an exhaust gas recirculation system configured to recirculate a portion of combustion gases discharged from the combustion chamber to the scavenge receiver;
said exhaust gas recirculation system having a blower for assisting the flow of combustion gases to said scavenge receiver;
The engine further comprises an exhaust system configured to exhaust another portion of combustion gases generated from the combustion chamber as exhaust gas,
The exhaust system has a turbine of a turbocharging system and is driven by the exhaust gas,
the engine further comprising an air intake system having a compressor of the turbocharging system, the compressor configured to supply pressurized scavenging air to the scavenging receiver;
The exhaust system has a carbon dioxide separator and a carbon dioxide storage system connected to an outlet of the carbon dioxide separator,
The carbon dioxide separation device receives an exhaust gas and separates at least a portion of the carbon dioxide in the exhaust gas, preferably by liquefying and/or solidifying the carbon dioxide, from the exhaust gas to produce the separated carbon dioxide. configured to deliver to said carbon dioxide storage unit;
institution. 2. An engine according to claim 1, comprising a control arranged to adjust the mass proportion of recirculated combustion gases in the scavenging gas to at least 40%, preferably from 40% to 55%. 3. The engine of claim 2, wherein the controller is configured to control the speed of the blower to adjust the proportion of recirculated combustion gases in the scavenged gas. An engine according to any one of claims 1 to 3, comprising a combustion gas-water cooler, preferably a combustion gas-sea water cooler, said combustion gas-water cooler preferably comprising a combustion gas from said engine. engine, upstream of a location where the flow of is split between a recirculated portion and another exhausted portion. An engine according to any one of claims 1 to 4, comprising a combustion gas-coolant heat exchanger and a cooling facility, said cooling facility passing cooling medium through said combustion gas-coolant heat exchanger. configured for circulation, said combustion gas-medium heat exchanger is preferably located downstream of a location where combustion gas flow from said engine is divided into a recirculated portion and another exhausted portion be done, institution. 6. An engine as claimed in any preceding claim, comprising a cooler downstream of the turbine for cooling the exhaust gas in order to liquefy and/or solidify the carbon dioxide in the exhaust gas. 7. The engine according to any one of claims 1 to 6, wherein the control unit controls the engine so that the temperature of the exhaust gas is -82°C or less when the exhaust gas reaches atmospheric pressure downstream of the turbine. an institution configured to control the operation of a An engine as claimed in any preceding claim, wherein the turbine is mechanically coupled to drive the compressor, preferably assisted by an electric drive motor. An engine as claimed in any preceding claim, wherein the compressor is driven by an electric drive motor and the turbine drives an electric generator or alternator. A method of operating a large two-stroke turbocharged uniflow scavenging internal combustion engine having multiple combustion chambers, comprising:
supplying a carbonaceous fuel to the combustion chamber;
burning the carbon-based fuel in the combustion chamber to generate a combustion gas containing carbon dioxide;
recirculating a portion of the combustion gases and discharging another portion of the combustion gases as an exhaust gas;
supplying pressurized scavenging gas to said combustion chamber comprising at least 40% by mass, preferably 40 to 55% by mass of recirculated combustion gas;
separating carbon dioxide from the exhaust gas in a carbon dioxide separation process;
storing the separated carbon dioxide in a storage unit;
A method, including 11. The method of claim 10, comprising subjecting the exhaust gas to one or more cooling and expansion processes thereby liquefying and/or solidifying the carbon dioxide downstream of the turbine. 12. The method of claim 11, comprising storing carbon dioxide in liquid or solid form in the storage unit. 13. A method as claimed in any one of claims 10 to 12, comprising controlling the speed of a blower in an exhaust recirculation system to adjust the proportion of recirculated combustion gases in the pressurized scavenging gas. at least part of the expansion process takes place in a turbine; 15. A method according to any of claims 10-14, wherein the engine comprises a flue gas-water cooler, preferably an exhaust gas-seawater cooler, the flue gas-water cooler preferably comprising the engine is located upstream of a location where the flow of combustion gas from the , more preferably to a temperature of 31° C. or less. 16. A method according to any one of claims 10 to 15, wherein the engine comprises a combustion gas-coolant heat exchanger, preferably a part through which the combustion gas flow from the engine is recirculated and an exhaust gas. and a cooling facility, said cooling facility circulating a cooling medium through said combustion gas-cooling medium heat exchanger to cool the exhaust gas, preferably below −10° C. to, more preferably to -15°C or below. Said engine comprises, downstream of said turbine, a cooler for further cooling the exhaust gas in order to liquefy and/or solidify the carbon dioxide in the exhaust gas, preferably to a temperature below -80°C at atmospheric pressure. 17. A method according to any of claims 10-16, comprising a vessel.

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