System for extracting cryogenic liquefied gas from a ship's tank, ship in question, use and procedure

Abstract

The invention relates to a system (2) for extracting cryogenic liquefied gas (F) from at least one ship tank (4) for a gas consumer (6), in particular as fuel for a ship propulsion system (6), comprising an extraction line (8) for extracting liquefied gas (F) from the ship tank (4), wherein the extraction line (8) extends into the ship tank (4), and a pump container (10) connected to the extraction line (8), which is arranged outside the ship tank (4) and is configured to extract the liquefied gas (F) from the ship tank (4) via the extraction line (8). According to the invention, it is proposed that the pump reservoir (10) has a differential pressure control device (12) which is configured to maintain an internal pressure (P P ) in the pump reservoir (10) such that it is lower than the internal pressure (P T) of the ship's tank (4) to transfer the liquefied gas (F) from the ship's tank (4) to the pump container (10) based on the pressure difference.

Description

[0001] The invention relates to a system for extracting cryogenic liquefied gas from at least one ship tank for a gas consumer, in particular as fuel for a ship propulsion system, comprising an extraction line for extracting liquefied gas from the ship tank, wherein the extraction line extends into the ship tank, and a pump container connected to the extraction line.

[0002] As emission limits become stricter and the maritime industry strives to reduce pollutant emissions, systems are increasingly being developed that allow the propulsion and general operation of equipment on board merchant ships using so-called fuel gases, such as natural gas. For gas operation, it is necessary to store the appropriate fuel gas, also known as combustible gas, on board the ship. Due to the lower energy density of natural gas compared to heavy fuel oil, liquefied natural gas (LNG) is frequently used as the fuel gas, as it allows for a relatively high energy density in the tank volume at relatively low pressure and cryogenic temperatures. Furthermore, the use of alternative fuel gases is also known. This allows the required amount of energy to be provided within the limited space available on board a ship.

[0003] Systems for gas supply based on LNG typically include a loading system, also known as a bunkering system, a corresponding LNG storage facility in the form of one or more ship tanks, and equipment for fuel conveyance, pressure boosting, fuel processing, and safety devices.

[0004] To pump the liquid fuel gas from the ship's tank, pumps, particularly submersible pumps, are used in the prior art and are located within the tank volume. However, the use of such submersible pumps has several disadvantages. Firstly, there is no free access to the pumps without first degassing the tanks, as the pumps are installed inside the fuel tank. This makes maintenance work complex. Furthermore, such pumps are susceptible to contamination and clogging of the associated filter, which is also frequently located within the tank volume and, in one embodiment, at the pump's intake housing. In addition, the service life of such pumps is inherently limited, and it is difficult to monitor their condition when they are located within the tank volume.Furthermore, removing such pumps from the tank volume is complex, as a lifting device must be kept within the so-called tank connection space, which is located above the tank.

[0005] Besides submersible pumps, deepwell pumps are also used, but these can require a significant height in the tank connection room, resulting from the height of the pump, motor, and lifting device. Although these pumps can be serviced without first purging the tank, the available space for maintenance is still limited. Furthermore, regular maintenance is required, and the pumps may operate suboptimally at their design point due to their hydraulic performance.

[0006] US 2020 / 0255009A1 relates to a method and device for transferring liquid cargo. KR 1020130127273A relates to a fuel gas supply device.

[0007] The invention is therefore based on the objective of eliminating, as far as possible, the disadvantages found in the prior art. In particular, a system for extracting cryogenic liquefied gas from at least one ship tank was to be provided in which pump maintenance is simplified and, moreover, the required volume of the tank connection space is kept as small as possible.

[0008] The invention solves the problem described above with regard to the system by arranging the pump container outside the ship's tank and by configuring it to extract the liquefied gas from the ship's tank via the extraction line, wherein the pump container has a differential pressure control device which is configured to control an internal pressure in the pump container such that it is lower than the internal pressure of the ship's tank in order to transfer the liquefied gas from the ship's tank to the pump container on the basis of the pressure difference.

[0009] The invention takes advantage of the fact that such a configuration, namely providing the pump housing outside the ship's tank, avoids the need to arrange pumps inside the ship's tank. Furthermore, it has the positive effect of requiring less equipment within the tank connection compartment, thereby reducing its size, i.e., its volume. The pump housing is preferably arranged both outside the ship's tank and outside the tank connection compartment.

[0010] According to one embodiment, the gas consumer is one or more of the following: ship propulsion, generator, steam generator, fuel cell.

[0011] According to the invention, the pump housing includes a pump designed to transfer the liquefied gas from the housing to the gas consumer or ship's propulsion system. In one embodiment, the pump housing has an opening, particularly a manhole, for pump replacement. This ensures that the pump is easily accessible through the opening or manhole in case maintenance or replacement is required. A further advantage of this configuration is that the volume of the pump housing is very small compared to the volume of the ship's tank. Therefore, if the pump housing needs to be opened, only a very small volume needs to be vented. For this purpose, the liquefied gas can be transferred from the pump housing to the ship's tank by increasing the pressure. This simultaneously prevents large quantities of greenhouse gas from being released into the atmosphere.For example, a spare pump can be carried on board the ship, which can replace the pump installed in the pump housing in case of maintenance. This also eliminates the need for redundancies, as maintenance or replacement of the pump is now comparatively simple.

[0012] The pump is preferably a fuel gas pump. The liquefied gas is drawn from the ship's tank to the pump by the pressure differential between the pump housing and the ship's tank. The pump housing is preferably located in the fuel preparation room. The pump housing's primary function is to achieve a sufficient net positive suction head (NPSH). This ensures that the pump, and in particular the fuel gas pump, can operate in the first place.

[0013] According to one embodiment, a first pressure sensor for measuring the internal pressure in the pump housing is assigned to the pump housing, and a second pressure sensor for measuring the internal pressure in the ship's tank is assigned to the ship's tank, with the pressure sensors being connected to the differential pressure control device via signal transmission. The pressure sensors enable pressure monitoring both within the pump housing and within the ship's tank.

[0014] According to one embodiment, the pump reservoir is fluidly connected to a compressor system via a control valve, the differential pressure control device being configured to selectively open the first control valve to the compressor system in order to regulate the pressure inside the pump reservoir to a lower pressure. According to one embodiment, the compressor system is a BOG compressor system of the ship. Alternatively, however, a separate compressor system can also be provided.

[0015] According to one embodiment, the ship's liquefied gas (LNG) heating system is fluidly connected to the ship's tank via a control valve. The differential pressure control device is configured to selectively open the valve and supply vaporized gas from the LNG heating system to the ship's tank when a minimum differential pressure between the pump housing and the ship's tank is not maintained. In other words, to maintain the minimum differential pressure, vaporized LNG can be directed into a vapor space within the ship's tank. This increases the pressure in the ship's tank and thus also the differential pressure.

[0016] According to one embodiment, the ship's tank is fluidly connected to the compressor system via a control valve. The differential pressure control device is configured to open the control valve when a maximum differential pressure between the pump housing and the ship's tank is exceeded, or when the maximum operating pressure of the ship's tank is exceeded, in order to supply vaporized gas from the ship's tank to the compressor system. This allows the pressure inside the ship's tank to be reduced, thereby regulating the differential pressure between the pump housing and the ship's tank, as well as the pressure within the ship's tank.

[0017] According to one embodiment, a control valve is associated with the extraction line, and a level control device is associated with the pump tank. This device is configured to control the fill level in the pump tank by actuating the control valve. According to another embodiment, a filter device with a filter element is installed upstream of the pump tank on the inlet side. The filter device is arranged outside the pump tank and / or the ship's tank and / or the tank connection compartment in such a way that the filter element can be replaced without opening the pump tank and / or the ship's tank and / or the tank connection compartment. This simplifies maintenance and / or replacement of the filter element.

[0018] According to one embodiment, the ship's tank has a sump, which is formed in particular in the bottom of the ship's tank, with the extraction line extending into the sump. In this way, almost complete emptying of the ship's tank is achieved.

[0019] The invention has been described above with reference to a system for extracting cryogenic liquefied gas from a ship's tank. In a further aspect, the invention relates to a ship with a ship's tank, a gas consumer, in particular a ship's propulsion system, and a system for extracting cryogenic liquefied gas from the ship's tank. The invention solves the problem described above with respect to the ship by designing the system according to one of the aforementioned embodiments. The ship benefits from the same advantages and preferred embodiments as the system according to the invention, and vice versa. To avoid repetition, reference is made to the above statements, and their content is incorporated herein.

[0020] In a further aspect, the invention relates to the use of a system according to one of the preceding embodiments for a ship, in particular for a ship powered by one of the following liquefied gases: liquefied natural gas (LNG), ethane, liquefied petroleum gas (LPG), ammonia. This use also takes advantage of the same benefits and preferred embodiments as the system and method according to the invention, and vice versa. To avoid repetition, reference is made to the above statements, and their content is incorporated herein.

[0021] In a further aspect, the invention relates to a method for extracting cryogenic liquefied gas from a ship's tank for a gas consumer, in particular as fuel for a ship's propulsion system. The method solves the aforementioned problem with the following steps: providing a pump container connected to a ship's tank via an extraction line; controlling the pressure in the pump container such that it is lower than the internal pressure of the ship's tank, in order to transfer the liquefied gas from the ship's tank to the pump container based on the pressure difference. This avoids the need to arrange a pump within the ship's tank or the tank connection compartment. Moreover, the method also utilizes the same advantages and preferred embodiments as the system, the ship, and the use according to the invention, and vice versa.To avoid repetition, reference is made to the above statements, and their content is included here.

[0022] The method is further developed by connecting the ship's tank to a compressor system via a control valve, the method comprising the step of: controlling, in particular reducing, the pressure inside the ship's tank by opening the control valve to the compressor system, especially when a maximum differential pressure between the pump tank and the ship's tank or a maximum operating pressure in the ship's tank is exceeded.

[0023] The method is further developed by connecting the ship's tank to a liquid gas heating system via a control valve, the method comprising the step of: controlling, in particular increasing the pressure inside the ship's tank by opening the control valve to the liquid gas heating system, especially when a minimum differential pressure between the pump tank and the ship's tank is undershot.

[0024] Depending on the design and arrangement of the ship's tank and fuel gas processing chamber, the minimum differential pressure is, for example, 0.5 bar. According to one embodiment, the maximum differential pressure is 1 to 1.5 bar. This means that, compared to conventional systems, the required pressure in the ship's tank for conveying the fuel to the gas consumer is low. This avoids the risk of pressure fluctuations in the ship's tank, which can occur particularly in heavy seas. The starting pressure in the ship's tank can, if necessary, be adjusted by reducing the steam recirculation to the bunkering system so that the pressure in the ship's tank after bunkering is sufficient to start the fuel gas supply.

[0025] Further features and advantages of the invention will become apparent from the attached claims and the following description, in which exemplary embodiments are explained in detail with reference to schematic drawings.

[0026] Specifically, we show: Fig. 1 a ship with a system according to the invention for extracting cryogenic liquefied gas for a gas consumer, in particular a ship's propulsion system, from the ship's tank in a schematic representation; Fig. 2 a block diagram of the method according to the invention.

[0027] Fig. Figure 1 shows a schematic representation of a ship 100. The ship 100 has a fuel tank 4. The ship 100 also has a gas consumer 6, which is exemplified as a ship propulsion system 6, and a system 2 for extracting cryogenic liquefied gas F as fuel for the ship propulsion system 6 from the fuel tank 4. A tank connection room 50 is arranged above the fuel tank 4. This, in turn, is connected via unspecified lines to a fuel gas treatment room 48.

[0028] System 2 has a withdrawal line 8 for extracting liquefied gas F from the ship's tank 4. The withdrawal line 8 extends into the ship's tank 4. As in Fig. As shown in Figure 1, the extraction line 8 extends into a lower section of the ship's tank 4. A pump housing 10 is fluidly connected to the extraction line 8. In the illustrated embodiment, the pump housing 10 is located in the fuel gas conditioning chamber 48. Therefore, the pump housing 10 is located outside the ship's tank 4 and is configured to extract the liquefied gas F from the ship's tank 4 via the extraction line 8. The pump housing 10 has a differential pressure control device 12. The differential pressure control device 12 is configured to maintain an internal pressure P. P in the pump container 10 such that it is lower than the internal pressure P Tof the ship's tank 4. In this way, the liquefied gas F can be transferred from the ship's tank 4 to the pump housing 10 based on the pressure difference, without the need to install pumps inside the ship's tank 4. This ensures very easy access to a pump 14 located inside the pump housing 10 in the event of maintenance work or a necessary replacement.

[0029] The pump housing 10 includes a pump 14. The pump 14 is preferably designed as a fuel gas pump 14. The pump 14 is configured to pump the liquefied gas F from the pump housing 10 to the gas consumer 6 or ship propulsion system 6. The pump housing has a housing opening 17, in particular a manhole. After opening the housing opening 17, the pump 14 located inside the pump housing 10 becomes accessible and can be serviced or replaced. The pump housing 10 is equipped with a first pressure sensor 18 for measuring the internal pressure P. P assigned to the pump housing. A second pressure sensor 20 for measuring the internal pressure P is assigned to the ship's tank 4. T assigned to the ship's tank 4. The pressure sensors 18, 20 are connected to the differential pressure control device 12 via signal transmission.

[0030] The pump reservoir 10 is also fluidly connected to a compressor system 24 of the ship 100 via a control valve 22. The differential pressure control device 12 is configured to selectively open the first control valve 22 to the compressor system 24 in order to regulate the pressure P P inside the pump reservoir 10, the pressure is regulated to a lower level. The compressor system 24 is located in the Fig. 1 shown embodiment a BOG compressor system 26 of the ship 100.

[0031] The ship 100 also has a liquefied gas heating system 30. The liquefied gas heating system 30 is fluidly connected to the ship's tank 4 via a control valve 44. The differential pressure control device 12 is configured to selectively open the control valve 44 and supply vaporized gas from the liquefied gas heating system 30 to the ship's tank 4 when a minimum differential pressure ΔP is reached. minThe pressure difference between pump reservoir 10 and ship tank 4 is not reached. By supplying the vaporized gas from the liquefied gas heating system 30 into ship tank 4, the pressure in ship tank 4 is increased, and thus also the differential pressure between pump reservoir 10 and ship tank 4.

[0032] The ship's tank 4 is also fluidly connected to the compressor system 24 via a control valve 32. The differential pressure control device 12 is configured to open the control valve 32 when a maximum differential pressure ΔP is exceeded. maxThe valve between pump reservoir 10 and ship tank 4, or when the maximum operating pressure of the ship tank is exceeded, is to be opened in order to supply vaporized gas from ship tank 4 to compressor system 24. By supplying the vaporized gas from ship tank 4 to compressor system 24, the pressure in ship tank 4 can be reduced, thus regulating the overall differential pressure between pump reservoir 10 and ship tank 4.

[0033] A control valve 33 is assigned to the extraction line 8. A level control device 34 is assigned to the pump reservoir 10. The level control device 34 is configured to control the fill level in the pump reservoir 10 by actuating the control valve 33. In this way, the fill level of the pump reservoir 10 can be monitored and controlled.

[0034] A filter assembly 36 with a filter element 38 is installed upstream of the inlet side of the pump housing 10. The filter element 38 serves to filter the liquefied gas F. The filter assembly 36 is located outside the pump housing 10 and also outside the ship's tank 4 and the tank connection compartment 50, such that the filter element 38 can be replaced without opening the pump housing 10, the ship's tank 4, or the tank connection compartment 50. This simplifies the maintenance of a pump 14 housed in the pump housing 10.

[0035] The ship tank 4 also has a sump 40, which is formed in particular in a base or on the underside 42 of the ship tank 4. The extraction line 8 extends into the sump 40, so that the ship tank 4 can be almost completely emptied. The supply of vaporized liquefied gas from the liquefied gas heating system 30 via the control valve 44 into the ship tank 4 is effected by the supply line 46. The tank connection room 50 is connected to bunkering stations 52 via a liquid line 54 and a vapor return line 56.

[0036] Fig. Figure 2 shows a block diagram of a process 200 for extracting cryogenic liquefied gas F from a ship tank 4. The process 200 comprises the following steps: providing 202 a pump reservoir 10, which is connected to a ship tank 4 via an extraction line 8; controlling 204 a pressure Pp in the pump reservoir 10 such that it is lower than an internal pressure P. Tof the ship's tank 4, in order to transfer the liquefied gas F from the ship's tank 4 to the pump container 10 based on the pressure difference.

[0037] Procedure 200 further includes the step: Control 206, in particular reducing the pressure P T inside the ship's tank 4 by opening the control valve 32 to the compressor system 24, especially when a maximum differential pressure ΔP max between pump reservoir 10 and ship tank 4, or the maximum operating pressure of the ship tank is exceeded. Furthermore, procedure 200 includes the step: Control 208, in particular increasing the pressure P T inside the ship's tank 4 by opening the control valve 44 to the liquefied gas heating system 30, especially when a minimum differential pressure ΔP min The minimum differential pressure ΔP between pump reservoir 10 and ship tank 4 is not reached. minDepending on the design and arrangement of the ship's tank and fuel gas processing room, the pressure is, for example, 0.5 bar, and the maximum differential pressure ΔP max e.g. 1 bar to 1.5 bar. Reference symbol list 2. Extraction system 4 ship tanks 6 Gas consumers, especially ship propulsion 8 Extraction line 10 pump containers 12 Differential pressure control device 14 Pump 17 Container opening 18 first pressure sensor of the pump reservoir 20 Second pressure sensor of the ship's tank 22 Control valve 24 compressor system 26 BOG compressor system 30 Liquid gas heating system 32 Control valve 33 Control valve 34 Level control device 36 Filter system 38 filter elements 40 swamp 42 Tank bottom 44 Control valve 46 Supply line for vaporized gas to the ship's tank 48 Fuel gas treatment room 50 Tank connection room 52 Bunker Station 54 Liquid line 56 Steam recirculation 100 ships 200 extraction procedures 202 Providing a pump container 204 Controlling the pressure in the pump reservoir 206 Reducing the pressure inside the ship's tank 208 Increasing the pressure inside the ship's tank F Liquefied gas P P Pressure inside the pump reservoir P T Pressure inside the ship's tank ΔP max maximum differential pressure between pump reservoir and ship tank ΔP min minimum differential pressure between pump reservoir and ship tank

Claims

[1] System (2) for extracting cryogenic liquefied gas (F) from at least one ship tank (4) for a gas consumer (6), in particular as fuel for a ship propulsion system (6), comprising: - a withdrawal line (8) for withdrawing liquefied gas (F) from the ship's tank (4), wherein the withdrawal line (8) extends into the ship's tank (4), - a pump container (10) connected to the extraction line (8), characterized by , that the pump container (10) is arranged outside the ship's tank (4) and is configured to extract the liquefied gas (F) from the ship's tank (4) via the extraction line (8), wherein the pump container (10) has a differential pressure control device (12) which is configured to maintain an internal pressure (P P ) in the pump reservoir (10) such that it is lower than the internal pressure (P T) of the ship's tank (4) to transfer the liquefied gas (F) from the ship's tank (4) to the pump container (10) based on the pressure difference, and wherein the pump container (10) has a pump (14) which is configured to pump the liquefied gas (F) from the pump container (10) to the ship's propulsion (6). [2] The system (2) according to claim 1, wherein the pump container (10) has a container opening (17), in particular a manhole, for replacing the pump (14). [3] The system (2) according to one of the preceding claims, wherein a first pressure sensor (18) for measuring the internal pressure (P) is provided to the pump container (10). P ) is assigned to the pump container (10) and a second pressure sensor (20) for measuring the internal pressure (P) is assigned to the ship's tank (4). T ) in the ship tank (4), wherein the pressure sensors (18, 20) are connected to the differential pressure control device (12) via signal transmission. [4] The system (2) according to one of the preceding claims, wherein the pump reservoir (10) is fluidly connected to a compressor system (24) via a control valve (22), and wherein the differential pressure control device (12) is configured to selectively open the first control valve (22) to the compressor system (24) in order to control the pressure (P P ) inside the pump reservoir (10) to regulate to a lower pressure. [5] The system (2) according to claim 4, wherein the compressor system (24) is a BOG compressor system (26) of a ship (100). [6] The system (2) according to one of the preceding claims, wherein a liquefied gas heating system (30) is fluidly connected to the ship's tank (4) via a control valve (44), and wherein the differential pressure control device (12) is configured to selectively open the control valve (44) and supply vaporized gas from the liquefied gas heating system (30) to the ship's tank (4) when a minimum differential pressure (ΔP)min ) between pump tank (10) and ship tank (4) is below the limit. [7] The system (2) according to any one of claims 4 to 6, wherein the ship tank (4) is fluidly connected to the compressor system (24) via a control valve (32), and wherein the differential pressure control device (12) is configured to open the control valve (32) when a maximum differential pressure (ΔP- max ) between pump container (10) and ship tank (4) or when the max. operating pressure in the ship tank (4) is exceeded, in order to supply evaporated gas from the ship tank (4) to the compressor system (24). [8] The system (2) according to one of the preceding claims, wherein a control valve (33) is associated with the extraction line (8) and a level control device (34) is associated with the pump container (10), which is configured to control a level in the pump container (10) by actuating the control valve (33). [9] The system (2) according to one of the preceding claims, wherein a filter device (36) with a filter element (38) received therein is connected upstream of the pump container (10) on the inlet side, and wherein the filter device (36) is arranged outside the pump container (10) and / or the ship tank (4) in such a way that the filter element (38) is replaceable without opening the pump container (10) and / or the ship tank (4). [10] The system (2) according to one of the preceding claims, wherein the ship tank (4) has a sump (40) which is formed in particular in a bottom or on the underside (42) of the ship tank (4), and wherein the extraction line (8) extends into the sump (40). [11] Ship (100) comprising a ship tank (4), a ship propulsion system (6) and a system (2) for extracting cryogenic liquefied gas (F) from the ship tank (4), wherein the system (2) is configured according to any of the preceding claims. [12] Use of a system (2) according to any one of claims 1-10 for a ship (100), in particular for a ship powered by one of the following liquefied gases (F): - Liquefied Natural Gas (LNG), - Ethan, - Liquefied Petroleum Gas (LPG), - Ammonia. [13] Method (200) for extracting cryogenic liquefied gas (F) from a ship tank (4) for a gas consumer (6), in particular as fuel for a ship propulsion system (6), comprising the steps: - Providing (202) a pump container (10) which is connected to the ship's tank (4) via a withdrawal line (8), wherein the pump container (10) has a pump (14) which is configured to pump the liquefied gas (F) from the pump container (10) to the ship's propulsion (6), - Controlling (204) a pressure (P p ) in the pump reservoir (10) such that it is lower than an internal pressure (P T) of the ship's tank (4) to transfer the liquefied gas (F) from the ship's tank (4) to the pump container (10) based on the pressure difference. [14] Method (200) according to claim 13, wherein the ship tank (4) is fluidly connected to a compressor system (24) via a control valve (32), and wherein the method (200) comprises the step: - Controls (206), in particular reducing pressure (P T ) inside the ship's tank (4) by opening the control valve (32) to the compressor system (24), especially when a maximum differential pressure (ΔP) max ) between pump container (10) and ship tank (4) or the max. operating pressure of the ship tank (4) is exceeded. [15] Method (200) according to claim 13 or 14, wherein the ship tank (4) is fluidly connected to a liquefied gas heating system (30) via a control valve (44), and wherein the method (200) comprises the step: - Taxes (208), in particular increasing the pressure (P T ) inside the ship's tank (4) by opening the control valve (44) to the liquefied gas heating system (30), especially when a minimum differential pressure (ΔP) min ) between pump tank (10) and ship tank (4) is undercut. [16] Method (200) according to claim 15, where the minimum differential pressure (ΔP) min ), particularly depending on the design and arrangement of the ship's tank and fuel gas processing room, is 0.5 bar and / or the maximum differential pressure (ΔP) max ) 1 bar to 1.5 bar.

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