KR20230127898A - Method and large two-stroke uniflow scavenged internal combustion engine for carbon dioxide capture - Google Patents

Abstract

A large two-stroke turbocharged single-flow scavenging internal combustion engine supplies carbon-based fuel to the combustion chamber, burns the carbon-based fuel in the combustion chamber to produce combustion gases containing carbon dioxide, recirculates a portion of the combustion gases, and exhausts another portion of the combustion gases. A method of operating an engine by supplying pressurized scavenging gas to a combustion chamber while discharging it as a gas is provided. The pressurized scavenging gas contains at least 40% by mass, preferably 40 to 55% of the recycled combustion gas, and in the carbon dioxide separation process, the carbon dioxide in the exhaust gas is separated and the separated carbon dioxide is stored in the storage unit 80.

Description

Method for capturing carbon dioxide and a large two-stroke single-flow scavenging internal combustion engine

The present invention relates to large two-stroke internal combustion engines, particularly large two-stroke single-flow scavenging internal combustion engines with crossheads that operate on carbon-based fuel (gaseous or liquid fuel), and methods of operating this type of engine to reduce carbon dioxide emissions. .

A large two-stroke turbocharged single-flow scavenging internal combustion engine with a crosshead is used as a propulsion system for large marine vessels or as a prime mover for power plants. Because of their enormous size, these two-stroke diesel engines are constructed differently from other internal combustion engines. The weight of the exhaust valve of the above internal combustion engine is up to 400 kg, the diameter of the piston is up to 100 cm, and the maximum working pressure of the combustion chamber is usually several hundred bar. The forces associated with these high pressure levels and piston sizes are enormous.

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

Engines running on gaseous fuel may operate according to an Otto cycle in which gaseous fuel is allowed in by a cylinder cover or fuel valve disposed intermediately along the length of the cylinder liner. That is, the engine accepts gaseous fuel during the upstroke of the piston (BDC to TDC), which begins long before the exhaust valve closes, compresses the gaseous fuel and scavenged mixture in the combustion chamber and injects a timed ignition means, such as liquid fuel. to ignite the compressed mixture at or near TDC.

Engines running on liquid fuel and engines running on gaseous fuel with high pressure injection also use gaseous or liquid fuel when the piston is close to or at TDC, i.e. when the compression pressure in the combustion chamber is at or close to its maximum value. injection, and thus operates according to the diesel cycle, i.e. compression ignition.

Liquid and gaseous fuels used in known large two-stroke turbocharged single-flow scavenging internal combustion engines generally contain carbon. That is, they are carbon-based fuels, and their combustion produces carbon dioxide that is released into the atmosphere. Carbon dioxide emissions are generally considered harmful to the environment and should be minimized or avoided.

KR20180072552 discloses a large two-stroke turbocharged single-flow scavenging internal combustion engine having a plurality of cylinders, and each cylinder has a scavenging port, a scavenging valve, and an exhaust gas receiving part connected to the cylinder through an individual exhaust valve, a turbocharger, and receiving exhaust gas An exhaust gas conduit connecting the negative outlet and the turbine of the turbocharger, a turbocharger compressor of the turbocharger driven by the turbine, a scavenging conduit connecting the outlet of the turbocharger compressor and the inlet of the scavenging air receiving section, and a scavenging conduit including a scavenging cooler ( 11), an exhaust gas containing a scavenging receiver connected to the cylinder through an individual scavenging port, an exhaust gas recirculation duct for recirculating a part of the exhaust gas back to the cylinder, and a blower or compressor for forcing the recirculated exhaust gas back into the cylinder. A recirculation conduit, a cylinder bypass conduit bypassing the cylinders by passing a portion of the hot scavenge air from the scavenging conduit upstream of the scavenger cooler to the turbocharger's turbine, and a boiler are provided. The engine is configured to move at least a first portion of the exhaust gases from the cylinders through the boiler.

It is an object of the present invention to provide an engine and method that overcomes or at least reduces the aforementioned problems.

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

According to a first aspect, there is provided a large two-stroke turbocharged single-flow scavenging internal combustion engine including a crosshead, wherein the internal combustion engine includes a plurality of combustion chambers each divided by a cylinder liner, a piston configured to reciprocate in the cylinder liner, and a cylinder cover. , a scavenging port disposed on the cylinder liner for introducing scavenging gas into the combustion chamber, an exhaust gas outlet disposed on the cylinder cover and controlled by an exhaust valve, and a fuel system configured to supply a carbon-based fuel to the combustion chamber, wherein the combustion chamber includes a carbon-based fuel. It is configured to generate combustion gases including carbon dioxide by burning the base fuel, the combustion chamber is connected to the scavenging gas receiving portion through the scavenging port and connected to the combustion gas receiving portion through the exhaust gas outlet, and the exhaust gas recirculation system is configured to generate combustion gases generated in the combustion chamber. configured to recirculate a portion of the combustion gas to the scavenging gas receiving portion, the exhaust gas recirculation system including a blower assisting the flow of the combustion gas to the scavenging gas receiving portion, and the exhaust gas system exhausting another portion of the combustion gas generated from the combustion chamber. The exhaust gas system includes a turbine of a turbocharger system driven by exhaust gas, the air inlet system includes a compressor of the turbocharger system, and the compressor supplies pressurized scavenge air to the scavenge gas receiving portion. The exhaust gas system includes a carbon dioxide separation system and a carbon dioxide storage unit connected to an outlet of the carbon dioxide separation system, wherein the carbon dioxide separation system receives the exhaust gas, and preferably solidifies and/or liquefies the carbon dioxide, thereby liquefying the exhaust gas. At least a portion of the carbon dioxide in the exhaust gas is separated from the exhaust gas, and the separated carbon dioxide is transported to the carbon dioxide storage device.

By operating the engine with combustion gas recirculation, carbon dioxide emissions from the engine are reduced by increasing the concentration of carbon dioxide in the exhaust gas, separating carbon dioxide from the exhaust gas more effectively, and storing carbon dioxide by separating the carbon dioxide from the exhaust gas.

In a possible embodiment of the first aspect, the engine comprises a controller configured to regulate the mass percentage of recycled combustion gases in the scavenging gas to at least 40%, preferably between 40% and 55%.

In a possible embodiment of the first aspect, the controller is configured to control the speed of the blower to regulate the percentage of combustion gases recirculated in the scavenging gas.

In a possible embodiment of the first aspect, the engine comprises a combustion gas-water cooler, preferably a combustion gas-water cooler, the combustion gas-water cooler preferably comprising a part into which the combustion gas stream of the engine is recirculated and a discharged one. It is placed upstream of the position where it is divided into other parts.

In a possible embodiment of the first aspect, the engine comprises a combustion gas-cooling medium heat exchanger and a cooling plant, the cooling plant being configured to circulate a cooling medium via combustion gases to the cooling medium heat exchanger, the combustion gas-cooling medium heat exchanger The steam is preferably arranged downstream of where the combustion gas stream of the engine is divided into a part to be recycled and another part to be exhausted.

In a possible embodiment of the first aspect, the combustion gas-cooling medium heat exchanger is connected to the cooling plant.

In a possible implementation of the first aspect, the engine includes a cooler downstream of the turbine that cools the exhaust gas to solidify carbon dioxide in the exhaust gas.

In a possible embodiment of the first aspect, the chiller is connected to a cooling plant.

In a possible embodiment of the first aspect, the controller is configured to solidify carbon dioxide in the exhaust gas by controlling the operation of the engine such that the temperature of the exhaust gas is below -82° C. when the exhaust gas reaches atmospheric pressure downstream of the turbine.

In a possible embodiment of the first aspect, the turbine is mechanically coupled to drive a compressor, preferably assisted by an electric drive motor. In order for the turbine to provide sufficient expansion to sufficiently cool the exhaust gases, there are operating conditions in which the turbine does not deliver sufficient energy to the compressor for operation, and in such operating conditions, additional energy is added to the turbocharging system by the electric drive motor. Should be.

In a possible embodiment of the first aspect, the compressor is driven by an electric drive motor and the turbine drives a generator or alternator (79). In this setup of the turbocharging system, the additional energy that may be required by the turbocharging system is from an external power source, which may be in the form of a generator or an alternator driven by the engine or a generator set associated with the engine, to an electric drive motor that drives the compressor. can be transmitted by

In a possible embodiment of the first aspect, the engine is operated according to the Otto cycle, and gaseous fuel is introduced from the fuel valve into the combustion chamber during the stroke of the piston from bottom dead center (BDC) to top dead center (TDC).

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

According to a second aspect, there is provided a method of operating a large two-stroke turbocharged single-flow scavenging internal combustion engine having a plurality of combustion chambers, the method comprising supplying a carbon-based fuel to the combustion chamber, burning the carbon-based fuel in the combustion chamber to produce carbon dioxide generating a combustion gas comprising, recirculating a portion of the combustion gas, discharging another portion of the combustion gas as exhaust gas, and supplying a pressurized scavenging gas to a combustion chamber, wherein the pressurized scavenging gas includes at least 40% by mass, preferably 40 to 55% of recycled combustion gas, in a carbon dioxide separation process, carbon dioxide is separated from exhaust gas, and the separated carbon dioxide is stored in a storage unit.

By operating the engine at a high combustion gas recirculation rate, the carbon dioxide concentration in the exhaust gas is increased, thereby facilitating the separation of carbon dioxide from the exhaust gas, and avoiding or at least reducing carbon dioxide emissions by the engine by separating the carbon dioxide from the exhaust gas and storing the carbon dioxide.

In a possible implementation of the second aspect, the method includes solidifying (freezing) at least a portion of the carbon dioxide in the exhaust gas. Freezing carbon dioxide makes it relatively simple to separate it from other components of the exhaust gas. Additionally, the storage of carbon dioxide in solid form requires little space and can be done in containers that do not need to be pressurized.

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

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

In a possible implementation of the second aspect, the method includes controlling the speed of a blower in an exhaust gas recirculation system that regulates the proportion of recycled combustion gases in pressurized scavenging gas.

In a possible implementation of the second aspect, at least part of the expansion process takes part in the turbine.

In a possible embodiment of the second aspect, the engine comprises a combustion gas-water cooler, preferably an exhaust gas-water cooler, preferably at a location where the combustion gas stream of the engine is divided into a recirculated portion and an exhaust portion. Arranged upstream, the method includes cooling the combustion gases with a combustion gas-water cooler, preferably to less than 40 degrees Celsius, more preferably to less than 31 degrees Celsius.

In a possible embodiment of the second aspect, the engine comprises a combustion gas-cooling medium heat exchanger and a cooling plant, the cooling plant passing a cooling medium through the combustion gas-cooling medium heat exchanger, preferably below -10 degrees Celsius, more preferably Preferably, it is configured to cycle at a temperature of -15 degrees Celsius or less.

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

In a possible implementation of the second aspect, the engine comprises a cooler downstream of the turbine to further cool the exhaust gas, preferably at a temperature below -80 degrees Celsius, preferably at atmospheric pressure, to solidify the carbon dioxide in the exhaust gas. .

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

In a possible implementation of the second aspect, the method includes pressurizing the recycled combustion gases to the blower compressor prior to mixing the combustion gases with compressed air.

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

According to the first aspect, by operating the engine with combustion gas recirculation, the carbon dioxide concentration in the exhaust gas is increased to separate the carbon dioxide from the exhaust gas more effectively, and the carbon dioxide emission by the engine is reduced by separating the carbon dioxide from the exhaust gas and storing the carbon dioxide. .

According to the second aspect, by operating the engine at a high combustion gas recirculation rate, the carbon dioxide concentration in the exhaust gas is increased to promote the separation of carbon dioxide from the exhaust gas, and the carbon dioxide is separated from the exhaust gas to store the carbon dioxide, thereby reducing the emission of carbon dioxide by the engine. Avoid or at least reduce.

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

In the following detailed description, an internal combustion engine will be described with reference to a large two-stroke low-speed turbocharged internal combustion crosshead engine of an exemplary embodiment. 1, 2 and 3 show an embodiment of a large slow speed turbocharged two-stroke diesel engine with crankshaft (8) and crosshead (9). 1 and 2 are a front view and a side view, respectively. 3 is a schematic representation of an embodiment of the large slow speed turbocharged two-stroke diesel engine of FIGS. 1 and 2 with an intake and exhaust system; In this embodiment, the engine has four cylinders in series. However, large slow speed turbocharged two-stroke internal combustion engines have 4 to 14 cylinders in rows, with cylinder liners supported by an engine frame (11). This engine can be used, for example, as a stationary engine operating a main engine of a ship or a generator of a power plant. The total power of this engine may range, for example, from 1,000 to 110,000 kW.

This engine, in this exemplary embodiment, is a two-stroke equipped with a scavenging port (18) in the lower area of the cylinder liner (1) and a central exhaust valve (4) in the cylinder cover (22) on top of the cylinder liner (1). It is a single flow scavenging type engine. The scavenging gas is passed from the scavenging receiver 2 through the scavenging port 18 of the individual cylinder liner 1 when the piston 10 is below the scavenging port 18 . Gaseous fuel (e.g. methanol, petroleum gas or LPG, natural gas LNG or ethane) is supplied by the electronic controller (60 ) and/or injected at high pressure (preferably greater than 300 bar) through the liquid fuel valve 50 when the piston 10 is at or near TDC. The fuel gas is introduced at a relatively low pressure of 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 and arranged in a central region of the length of the cylinder liner 1 . The inflow of gaseous fuel occurs when the compression pressure is relatively low, i.e. when the piston reaches TDC and is well below the compression pressure, so the inflow is possible at a relatively low pressure.

The piston 10 of the cylinder liner 1 compresses a charge of gaseous fuel and scavenging gas (or compresses the scavenging gas if the operation consists of liquid fuel injection only at TDC) and the ignition at or near TDC is preferably a cylinder cover Triggered by injection of liquid fuel at high pressure of the liquid fuel valve 50 disposed at 22 or through compression in the case of liquid fuel injection only at or near TDC. Combustion follows, and combustion gases containing carbon dioxide are produced.

When the exhaust valve 4 is opened, the combustion gases flow through the combustion gas duct connected to the cylinder 1 to the combustion gas receiver 3, and then through the combustion gas conduit 19 containing combustion gas to the water cooler. It flows to (65). The combustion gas-water cooler 65 is operated with seawater when the engine is installed on a marine vessel. The action of the flue gas-water cooler 65 is controlled by the controller 40, from a temperature of 425 to 475 degrees Celsius at the inlet of the flue gas-water cooler 65, to 40 °C at the outlet of the flue gas-water cooler 65. It operates to cool the combustion gases to less than 35 degrees Celsius, preferably less than 35 degrees Celsius, most preferably less than 31 degrees Celsius. Preferably at a location downstream of the combustion gas-water cooler 65, the flow of combustion gases is split into a portion flowing into the combustion gas recirculation system 60 and another portion flowing into the exhaust system. Combustion gas recirculation system 60 is connected to a scavenging system as described further below. The combustion gas recirculation system 60 includes a conduit connected to the scavenging system and may include a scrubber 70 (preferably water operated) to purify the combustion gases. The combustion gas recirculation system 60 also includes a blower 75 (preferably driven by an electric drive motor 76) for directing combustion gases through the combustion gas 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 ratio of combustion gas to scavenging gas (on a mass basis) by adjusting the operation of the blower 75 . The controller 40 is configured in an embodiment to adjust the proportion of combustion gas in the scavenging gas (by mass) to 40% or more, preferably 45% or more, most preferably 40 to 55%. The combustion gas ratio is defined as the percentage of the combustion gas mass of the total gas mass introduced into the engine.

The exhaust system comprises an exhaust conduit 63 which contains the exhaust gas to the cooling medium heat exchanger 66 and leads to the turbine 6 of the turbocharger 5 . An exhaust gas-cooling medium heat exchanger 66 is operatively connected to a cooling plant 68 . The cooling plant 60 circulates the cooling medium through the combustion gas-cooling medium heat exchanger 66 to reduce the exhaust gas at the outlet of the cooling medium heat exchanger 66 to -10 degrees Celsius or less, more preferably -15 degrees Celsius. It is configured to be cooled to a temperature below. As a result, the water in the exhaust gas solidifies (forms ice or snow) and is separated in a gravity or centrifugal process and removed via 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 cooling media known for industrial cooling installations. The operation of the cooling medium heat exchanger 66 is controlled by the controller 40 to obtain the temperature of the exhaust gas at the outlet of the cooling medium heat exchanger 66 at a desired temperature.

At the outlet of the cooling medium heat exchanger (66) the exhaust gases flow to the inlet of the turbine (6). At the exit of the turbine 6, the exhaust gases, via expansion within the turbine 6, reach a temperature of less than -80 degrees Celsius, preferably less than -82 degrees Celsius, and ambient (atmospheric) pressure. Under these conditions, the carbon dioxide in the exhaust gas is solidified (frozen) and separated, for example by gravity or centrifugation. 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 allowed to flow through outlet 21 into the atmosphere.

In this embodiment, the engine includes a cooler downstream of the turbine to further cool the exhaust gas, preferably at a temperature below -80 degrees Celsius, preferably at atmospheric pressure, to solidify 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 immediately downstream of the cooler 69, such as through a gravity or centrifugal process. The separated solid carbon dioxide is stored in the carbon dioxide storage unit 80. The carbon dioxide stored in the carbon dioxide storage unit 80 may then be stored in a more permanent storage unit for storing the captured carbon dioxide.

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

The compressor 7 delivers pressurized scavenging air to the scavenging conduit 13 leading to the scavenging air receiver 2 . The scavenged air in this conduit 13 passes through the intercooler 14 for cooling of the scavenged air.

Either upstream (shown) or downstream (not shown) of the intercooler 14, a combustion gas recirculation system 60 is connected to the scavenging conduit 13. At this point, the recycled combustion gases are mixed with the scavenging air to form the scavenging gas. The controller 40 is configured such that the scavenging gas comprises between 40 and 55% of the combustion gas mass.

If the compressor 7 of the turbocharger 5 does not deliver sufficient pressure to the scavenging air receiver 2, i.e. under low load or part load conditions of the engine, the cooled scavenging or scavenging gases will generate electricity to pressurize the scavenging flow. It passes via the auxiliary blower 16 driven by the motor 17. At higher engine loads, after the turbocharger compressor (7) delivers sufficiently pressurized scavenging air, the auxiliary blower (16) is bypassed via the non-return valve (15).

Controller 40 (electronic control unit), which may consist of a number of interconnected electronic devices including a processor and other hardware to perform the functions of the controller, generally controls the operation of the engine and, for example, and timing), liquid fuel injection (amount and timing), opening and closing of the exhaust valve 4 (timing and lift range), recirculated combustion gas ratio and operation of various coolers. Here, the controller 40 controls the operating conditions of the engine (engine load, engine speed, blower speed, scavenging gas temperature, combustion gas temperature at various locations, exhaust gas temperature at various locations, scavenging system, combustion chamber, exhaust gas system and It receives various signals from sensors that inform the controller of the pressure in the combustion gas recirculation system.). Preferably, the engine includes a variable timing exhaust valve actuation system allowing individual control of exhaust valve timing for each combustion chamber. The controller 40 has signal lines or wireless connections to the fuel valve 30, the liquid fuel valve 50, the exhaust valve actuator, and an angular position sensor that senses the angle of the crankshaft and generates a signal indicative of the position of the crankshaft. A pressure sensor connected via, preferably in the cylinder cover 22 or alternatively in the cylinder liner 1 generates a signal representing the pressure in the combustion chamber.

Depending on the size of the engine, the cylinder liner 1 can be manufactured in different sizes, with cylinder bores typically ranging from 250 mm to 1000 mm and corresponding typical lengths ranging from 1000 mm to 4500 mm.

The cylinder liner 1 is mounted on a cylinder frame 23 in which a cylinder cover 22 is disposed on top of each cylinder liner 1 with an airtight interface therebetween. 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 circumferential direction connected to a cylinder lubrication line for supplying cylinder lubrication oil when the piston 10 passes through the cylinder lubrication holes 25, and then the piston ( A piston ring (not shown) of 10) distributes cylinder lubricating oil to the working surface (inner surface) of the cylinder liner 1.

Liquid fuel valves 50 (generally one or more, preferably three or four per cylinder) are mounted on the cylinder cover 22 and are connected to a liquid fuel source (not shown). The liquid fuel valve 50 is preferably disposed 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 amount of liquid fuel are controlled by the controller 40 . The liquid fuel valve 50 is only used to inject a small amount of ignition fluid (pilot) when the engine is operating in gaseous fuel mode. When the engine is operating in liquid fuel mode, the amount of liquid fuel required to operate the engine at actual engine load is injected through liquid fuel valve 50 . The cylinder 22 cover may be provided with a prechamber (not shown) and a tip of a liquid fuel valve 50, which is generally provided with a nozzle having one or more nozzle holes, where pilot oil (ignition fluid) triggers ignition. To do this, it is sprayed and sprayed into the prechamber. The prechamber helps ensure stable ignition. In one embodiment, the prechamber is a double prechamber, ie two prechambers connected in series.

The fuel valve 30 is installed on the cylinder liner 1 (or cylinder cover 22) at substantially the same height as the rear end of the fuel valve 30, the nozzle of which protrudes from the inner surface of the cylinder liner 1 and the outer wall of the cylinder liner 1. )) to be installed. In general, each cylinder liner 1 circumferentially distributed around the cylinder liner 1 (preferably evenly distributed in the circumferential direction) has one or two, or possibly up to three or four fuel valves ( 30) is provided. The fuel valve 30 is disposed substantially midway along the length of the cylinder liner 1 in one embodiment. Fuel valve 30 is connected to a pressurized source of gaseous fuel 40 (eg methanol, LPG, LNG, ethane or ammonia). That is, when the fuel is delivered to the fuel valve 30, the fuel is in a gaseous state. Since gaseous fuel is introduced 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 present in the cylinder liner 1, which is normally delivered to the fuel valve 30. For gaseous fuels, a pressure of less than 20 bar is sufficient. The fuel valve 30 is connected to a controller 40 that determines the opening/closing timing of the fuel valve and the opening time of the fuel valve 30 .

The liquid fuel for ignition is, in one embodiment, fuel oil, marine diesel, heavy oil, ethanol or dimethyl ether (DME).

The airframe operating mode can be one of several operating modes of the engine. Other modes may include a liquid fuel operating mode in which all fuel required for engine operation is provided in liquid form through the liquid fuel valve 50 . In the gaseous fuel operating mode, the engine operates using gaseous fuel as the primary fuel introduced during the stroke of the piston from BDC to TDC at relatively low pressures. That is, it provides most of the energy supplied to the engine. In comparison, liquid fuel constitutes a relatively small amount of fuel that makes a relatively small contribution to the amount of energy supplied to the engine, and the purpose of liquid fuel is timing ignition. That is, the liquid fuel serves as an ignition fluid.

Thus, the engine of this embodiment may be a dual fuel engine. That is, the engine has a mode in which it operates only on liquid fuel and a mode in which it operates almost exclusively on gaseous fuel.

The engine supplies carbon-based fuel (liquid and/or gaseous fuel) to the combustion chamber, burns the carbon-based fuel in the combustion chamber to produce combustion gases containing carbon dioxide, recycles a portion of the combustion gases, and recycles another portion of the combustion gases. is exhausted as exhaust gas, and pressurized scavenging gas is supplied to the combustion chamber, the pressurized scavenging gas contains at least 40% by mass, preferably 40 to 55% by mass of recycled combustion gas, and the exhaust gas in the carbon dioxide separation process It operates by separating carbon dioxide from the carbon dioxide and storing the separated carbon dioxide in the storage unit (80).

In this process, the exhaust gas undergoes a cooling and expansion process in which carbon dioxide in the exhaust gas is solidified (freezes) at the outlet of the turbine 6 in the cooler 69 or downstream of the turbine 6. The frozen carbon dioxide is stored in solid form in the storage unit 80 after separation, for example, in a gravity or centrifugal separation process. Storage unit 80 is in one embodiment an insulated non-pressurized vessel or tank.

The controller 40 controls the speed of the blower 75 in the exhaust gas recirculation system 60 to regulate the percentage of the combustion gases recirculated in the pressurized scavenging gas to a mass percentage of preferably at least 40% of the carbon dioxide in the combustion gases. increase the concentration. In one embodiment, the controller 40 is configured to adjust the recycled combustion gas proportion to result in a carbon dioxide concentration in the combustion gas that is at least doubled as compared to operating without combustion gas recirculation.

At least a part of the expansion process of the exhaust gas takes part in the turbine 6 to solidify the carbon dioxide in the exhaust gas by creating a large drop in the temperature and pressure of the exhaust gas, preferably atmospheric pressure and a temperature below -82 degrees.

Figure 4 shows another engine embodiment. In these embodiments, structures and features identical or similar to corresponding structures and features previously described or illustrated herein are denoted by reference numerals as previously used for simplicity. Since the engine and its operation in this embodiment are mostly the same as in the previous embodiment, only differences from the previous embodiment will be described in detail.

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 setup of the turbocharging system, the additional energy that may be required by the turbocharging system is delivered by an electric drive motor 78 which drives the compressor 7 . Here, the electric drive motor 78 is driven by a power supply, which may be in the form of a generator or an alternator driven by the engine, or by a generator set associated with the engine.

In this embodiment, the engine is shown as a compression ignition engine (operating on the diesel principle), and a carbon-based fuel (gaseous or liquid) is injected at high pressure when the piston 10 is at or near TDC. The illustrated engine does not require a fuel inlet valve 30 in the prechamber or cylinder liner 10. However, the engine according to this embodiment may be operated according to the Otto principle in which gaseous fuel is introduced during the stroke of the piston 10 from BDC to TDC.

In this embodiment, the controller 40 determines that the conditions (i.e., pressure and temperature) at the outlet of the turbine 6 are such that the carbon dioxide in the exhaust gas is solidified, and the solidified carbon dioxide is released from the outlet of the turbine 6 through a gravity or centrifugal separation process. It is separated from and stored in the carbon dioxide storage unit 80.

5 shows another engine embodiment. In these embodiments, structures and features identical or similar to corresponding structures and features previously described or illustrated herein are denoted by reference numerals as previously used for simplicity. Since the engine and its operation in this embodiment are mostly the same as in the previous embodiment, only differences from the previous embodiment will be described in detail.

Although the engine shown in this embodiment is a gas intake engine operating according to the Otto principle, it should be understood that this embodiment may operate as well as a high pressure fuel injection engine operating according to the diesel principle.

In this embodiment, no measures are taken to achieve a lower than normal (normal) temperature of the exhaust gas at the outlet of the turbine 6 . There is therefore no need for a cooling medium cooler where the combustion gases are connected to a water cooler or the exhaust gases are connected to the cooling plant. Accordingly, the temperature of the exhaust gas will be in the normal temperature range of 180 to 250 degrees Celsius.

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

In one embodiment, the carbon dioxide separation unit 88 dries the exhaust gas, compresses the exhaust gas, passes the exhaust gas to one or more refrigeration loops, and then undergoes an expansion process to liquefy or solidify the carbon dioxide in the exhaust gas; Afterwards, the liquid or solid exhaust carbon dioxide is separated and stored in the liquid or solid carbon dioxide storage unit 80.

In another embodiment (not shown), carbon dioxide separation unit 88 uses a carbon dioxide absorbent (eg, using an absorbent solvent) operatively connected to a regenerator, such as an amine regenerator, to separate carbon dioxide from the exhaust gas. The regenerator can use steam to remove CO2 from the absorbent solvent.

Various aspects and embodiments have been described in connection with various embodiments herein. Embodiments can be combined in various ways. However, other modifications to the disclosed embodiments may be understood and effected by those skilled in the art when practicing the claimed subject matter upon a study of the drawings, disclosure and appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plural. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that these combinations cannot be used to advantage. Reference signs used in the claims are intended to limit the scope. should not be interpreted

Claims (17)

In a large two-stroke turbocharged single-flow scavenging internal combustion engine with a crosshead (9),
a plurality of combustion chambers each divided into a cylinder liner 1, a piston 10 configured to reciprocate within the cylinder liner 1, and a cylinder cover 22;
a scavenging port (18) disposed within the cylinder liner (1) for introducing scavenging gas into the combustion chamber;
an exhaust gas outlet disposed within the cylinder cover 22 and controlled by the exhaust valve 4;
a fuel system configured to supply a carbon-based fuel to the combustion chamber;
An exhaust gas recirculation system (60) configured to recirculate a part of the combustion gas generated in the combustion chamber to the scavenging air receiving portion (2), including a blower (75) for assisting the flow of combustion gas to the scavenging air receiving portion (2). an exhaust gas recirculation system 60;
an exhaust gas system configured to exhaust another part of the combustion gas generated in the combustion chamber as exhaust gas; and
An air inlet system comprising a compressor 7 of the turbocharger system 5, wherein the compressor 7 is configured to supply pressurized scavenging air to the scavenging air receiving portion 2;
the combustion chamber is configured to combust the carbon-based fuel to produce a combustion gas comprising carbon dioxide;
the combustion chamber is connected to the scavenging gas receiving portion 2 through the scavenging port 18 and to the combustion gas receiving portion 3 through the exhaust gas outlet;
The exhaust gas system includes a turbine (6) of a turbocharger system (5) driven by the exhaust gas,
The exhaust gas system includes a carbon dioxide separation system and a carbon dioxide storage unit (80) connected to an outlet of the carbon dioxide separation system;
The carbon dioxide separation system receives the exhaust gas and preferably separates at least a portion of the carbon dioxide in the exhaust gas from the exhaust gas by liquefying and/or solidifying the carbon dioxide and returns the separated carbon dioxide to the carbon dioxide storage unit 80. A large two-stroke turbocharged single-flow scavenging internal combustion engine configured to deliver. According to claim 1,
and a controller (40) configured to regulate the mass percentage of recycled combustion gases in the scavenging gas to at least 40%, preferably between 40% and 55%. According to claim 2,
wherein the controller (40) is configured to control the speed of the blower (75) to regulate the percentage of combustion gases recirculated in the scavenge gas. According to any one of claims 1 to 3,
a combustion gas-water cooler 65, preferably a combustion gas-water cooler 65, wherein the combustion gas-water cooler 65 preferably divides the combustion gas stream of the engine into a recirculated part and another part from which it is discharged. A large two-stroke turbocharged single-flow scavenging internal combustion engine, arranged upstream of the split location. According to any one of claims 1 to 4,
a combustion gas-cooling medium heat exchanger 66 and a cooling plant 68, the cooling plant 68 being configured to circulate the cooling medium through the combustion gas-cooling medium heat exchanger 66; A combustion gas-cooling medium heat exchanger (66) is preferably disposed downstream of where the engine's combustion gas stream is divided into a portion to be recycled and another portion to be exhausted. According to any one of claims 1 to 5,
A large two-stroke turbocharged single flow scavenging internal combustion engine comprising a cooler (69) downstream of the turbine (6) for cooling the exhaust gas to liquefy and/or solidify carbon dioxide in the exhaust gas. According to any one of claims 1 to 6,
The controller (40) is configured to control the operation of the engine such that the temperature of the exhaust gas is below -82 degrees Celsius when the exhaust gas reaches atmospheric pressure downstream of the turbine (6). Charging single flow scavenging internal combustion engine. According to any one of claims 1 to 7,
The turbine (6) is preferably mechanically coupled to drive the compressor (7) assisted by an electric drive motor (77).
According to any one of claims 1 to 7,
The compressor (7) is driven by an electric drive motor (78) and the turbine (7) drives a generator or alternator (79). A method of operating a large two-stroke turbocharged single-flow scavenging internal combustion engine having a plurality of combustion chambers,
supplying carbon-based fuel to the combustion chamber;
generating a combustion gas containing carbon dioxide by burning the carbon-based fuel in the combustion chamber;
recirculating a portion of the combustion gas and exhausting another portion of the combustion gas to exhaust gas;
supplying pressurized scavenging gas to the combustion chamber, wherein the pressurized scavenging gas comprises at least 40% by mass of recycled combustion gas, preferably between 40 and 55%;
Separating carbon dioxide from the exhaust gas in a carbon dioxide separation process, and
and storing the separated carbon dioxide in a storage unit (80). According to claim 10,
A method of operating a large two-stroke turbocharged single flow scavenging internal combustion engine comprising subjecting the exhaust gas to one or more cooling and expansion processes to liquefy and/or solidify the carbon dioxide downstream of the turbine (6). According to claim 11,
and storing the carbon dioxide in liquid or solid form in the storage unit (80). According to any one of claims 10 to 12,
controlling the speed of a blower (75) in an exhaust gas recirculation system that regulates the percentage of combustion gases recirculated in the pressurized scavenging gas. According to any one of claims 10 to 13,
A method of operating a large two-stroke turbocharged single flow scavenging internal combustion engine in which at least part of the expansion process takes part in the turbine (6). According to any one of claims 10 to 14,
The engine comprises a combustion gas-water cooler (65), preferably an exhaust gas-sea water cooler, preferably disposed upstream of a position where the combustion gas stream of the engine is divided into a recirculated portion and an exhaust portion; ,
The method comprises a step of cooling the combustion gases with the combustion gas-water cooler (65), preferably below 40 degrees Celsius, more preferably below 31 degrees Celsius. How the internal combustion engine works. According to any one of claims 10 to 15,
The engine preferably comprises a combustion gas-cooling medium heat exchanger (66) and a cooling plant (68) disposed downstream of a position where the combustion gas stream of the engine is divided into a recirculated portion and an exhaust portion, wherein the The cooling plant 68 circulates the cooling medium through the combustion gas-cooling medium heat exchanger 66 to cool it preferably to a temperature of -10 degrees Celsius or less, more preferably to a temperature of -15 degrees Celsius or less. A method of operating a turbocharged single flow scavenging internal combustion engine, configured to. According to any one of claims 10 to 16,
The engine further cools the exhaust gas at a temperature preferably below -80 degrees Celsius, preferably at atmospheric pressure, to liquefy and/or solidify carbon dioxide in the exhaust gas. 69), a method of operating a turbocharged single flow scavenging internal combustion engine.