Self-cleaning device for LNG carrier fuel tank sump

Abstract

The application discloses a self-cleaning device for a fuel tank sump of an LNG ship, which comprises a sump, a bottom injection pipe, an annular return pipe, a cofferdam and a plurality of cleaning pipes. The annular return pipe is sleeved outside two submerged pumps and is installed at the upper portion of the sump, and the annular return pipe is connected with one end of the bottom injection pipe through an S-shaped connecting pipe. The cofferdam is coaxially fixed on the inner bottom surface of the sump, and a plurality of perforations are radially arranged on the bottom circumference of the cofferdam. The cleaning pipe is L-shaped and comprises a vertical portion and a horizontal portion, the upper ends of the vertical portions of the plurality of cleaning pipes are circumferentially and evenly connected with the annular return pipe, the horizontal portions of the plurality of cleaning pipes are correspondingly inserted into the plurality of perforations of the cofferdam, and a plurality of spray nozzles are arranged on the inner segment bottom and the two sides of each cleaning pipe located in the inner cavity of the cofferdam. The self-cleaning device can flush the sump by using the return condition of LNG, can prevent impurities from gathering below the bottom suction port of the submerged pump, and can guarantee the normal work of the submerged pump.

Description

Technical Field

[0001] This invention relates to a self-cleaning device for the LNG ship fuel tank collection well. Background Technology

[0002] With increasingly stringent environmental requirements for the ocean, liquefied natural gas (LNG) has been widely adopted as a new type of ship fuel. Liquid LNG in fuel tank 100 is injected through LNG refueling pipeline 101. Two submersible pumps 20 are installed inside fuel tank 100 to extract LNG for the ship's propulsion system. A collection well 10 is recessed at the bottom of fuel tank 100 corresponding to the two submersible pumps, and the bottom suction ports of the two submersible pumps extend into the collection well 10. When the submersible pumps 20 are operating, the liquid LNG in fuel tank 100 flows towards the collection well 10, and is then extracted by the submersible pumps 20 and transported to the ship's propulsion system through the gas supply pipeline 201. During this process, the flow of LNG carries impurities deposited at the bottom of fuel tank 100 towards the collection well 10. Currently, impurities in the LNG are blocked by the suction filter of the submersible pump 20. These blocked impurities accumulate directly below the suction port of the submersible pump 20. If not cleaned regularly, the suction filter may become clogged with impurities, or even be drawn into both submersible pumps 20, affecting their normal operation. When the ship's propulsion system (main engine and generator) is not operating, the BOG produced by the fuel tank 100 cannot be consumed. Therefore, the LNG will flow back to the fuel tank 100 through the gas supply line 201 and the LNG refueling line 101 (see...). Figure 1a , Figure 1b and Figure 1c ). Summary of the Invention

[0003] The purpose of this invention is to overcome the defects of the prior art and provide a self-cleaning device for the LNG ship fuel tank collection well. It uses the LNG backflow condition to flush the collection well, which can prevent impurities from accumulating below the bottom suction port of the submersible pump, thereby ensuring the normal operation of the submersible pump.

[0004] The objective of this invention is achieved as follows: a self-cleaning device for an LNG carrier fuel tank sump, comprising a sump, a bottom injection pipe, an annular return pipe, a cofferdam, and several cleaning pipes; the sump is located at the bottom of the fuel tank, and two submersible pumps are vertically installed inside the fuel tank, with their bottom suction ports extending into the sump; the bottom injection pipe is horizontally located at the lower part of the fuel tank along its length and on one side of the sump, with its middle section connected to the LNG refueling pipeline of the fuel tank; wherein,

[0005] The annular return pipe is sleeved around the two submersible pumps and installed on the upper part of the collection well. The annular return pipe is connected to one end of the bottom injection pipe through an S-shaped connecting pipe.

[0006] The cofferdam is coaxially fixed to the inner bottom surface of the liquid collection well with the annular return pipe. The cofferdam is a cylindrical body with an outer diameter smaller than the inner diameter of the liquid collection well but larger than the outer distance between the two submersible pumps. The height of the cofferdam is lower than the installation height of the annular return pipe. Several perforations are radially evenly distributed around the bottom circumference of the cofferdam.

[0007] The cleaning pipe has a vertical section and a horizontal section and is L-shaped. The upper ends of the vertical sections of several cleaning pipes are evenly distributed around the annular return pipe. The horizontal sections of several cleaning pipes are inserted into several holes in the cofferdam in a corresponding manner. Several nozzles are opened at the bottom of the inner section and on both sides of the inner section of each cleaning pipe located in the inner cavity of the cofferdam.

[0008] The self-cleaning device for the LNG ship fuel tank collection well described above, wherein the annular return pipe is fixed to the upper part of the inner wall of the collection well by several supports.

[0009] The self-cleaning device for the LNG ship fuel tank collection well of the present invention has the following characteristics:

[0010] 1. By introducing the LNG injection pipe into the collection well and using the LNG reflux to flush the collection well, no additional purging process is required. This can disperse impurities accumulated in the collection well within the fuel tank, preventing impurities from accumulating directly below the bottom suction port of the submersible pump, thereby ensuring the normal operation of the submersible pump.

[0011] 2. After self-cleaning, impurities will accumulate around the perimeter of the cofferdam, making subsequent cleaning easier.

[0012] 4. The self-cleaning device of the present invention has a simple structure and low cost, and can be installed using only commonly used pipes, profiles, brackets, etc.

[0013] 5. The self-cleaning device of the present invention has a reasonable structure. The annular return pipe in the collection well is closely attached to the top of the inner wall of the collection well, and the cofferdam is located at the bottom of the collection well. Neither of these conditions affects the installation and maintenance of the submersible pump in the collection well.

[0014] 6. The arrangement of the self-cleaning device of the present invention is also applicable to liquefied gas carriers carrying other cargoes, and is also applicable to LNG type A tanks, type B tanks and type C tanks. Attached Figure Description

[0015] Figure 1a This is a side view of a typical LNG carrier fuel tank;

[0016] Figure 1b This is a top-down perspective view of a typical LNG ship fuel tank;

[0017] Figure 1c This is a front view of a standard LNG carrier fuel tank;

[0018] Figure 2 This is a front view of the self-cleaning device for the LNG ship fuel tank collection well of the present invention.

[0019] Figure 3 yes Figure 2 Enlarged view of the P-section;

[0020] Figure 4 yes Figure 2 View A in the diagram. Detailed Implementation

[0021] The invention will now be further described with reference to the accompanying drawings.

[0022] Please see Figures 2 to 4 The self-cleaning device for the LNG ship fuel tank collection well of the present invention includes a collection well 10, a bottom injection pipe 1, an annular return pipe 3, a cofferdam 4, and four cleaning pipes 5.

[0023] The fuel tank 100 is a horizontal cylindrical shape; the liquid collection well 10 is located at the bottom of one side of the fuel tank 100. The liquid collection well 10 is cylindrical or cylindrical. In this embodiment, the liquid collection well 10 is cylindrical. Two submersible pumps 20 are installed inside the fuel tank 100. The bottom suction ports of the two submersible pumps 20 extend into the liquid collection well 10.

[0024] The bottom injection pipe 1 is horizontally located in the lower part of the fuel tank 100 along the length of the fuel tank 100 and is located on one side of the liquid collection well 10. The middle part of the bottom injection pipe 1 is connected to the LNG refueling pipeline 101 that is vertically inserted into the fuel tank 100.

[0025] The planar shape of the annular return pipe 3 is adapted to the planar shape of the collection well 10. The annular return pipe 3 is sleeved around the two submersible pumps 20 and installed on the top of the collection well 10 through four brackets 30. The four brackets 3 are evenly distributed around the circumference and welded to the top of the inner wall of the collection well 10. The annular return pipe 3 is connected to one end of the bottom injection pipe 1 through the S-shaped connecting pipe 2.

[0026] The cofferdam 4 is coaxially fixed to the inner bottom surface of the collection well 10. The cofferdam 4 is a cylindrical body with an outer diameter smaller than the inner diameter of the collection well 10 but larger than the outer distance between the two submersible pumps 20. The planar shape of the cofferdam 4 is adapted to the planar shape of the collection well 10. The height of the cofferdam 4 is lower than the installation height of the annular return pipe 3. Four perforations are evenly distributed radially around the bottom circumference of the cofferdam 4.

[0027] The cleaning pipe 5 has a vertical section and a horizontal section, forming an L-shape. The upper ends of the vertical sections of the four cleaning pipes 5 are evenly distributed around the annular return pipe 3. The horizontal sections of the four cleaning pipes 5 are inserted into the four perforations of the cofferdam 4 in a corresponding manner, and the ends of the horizontal sections of the four cleaning pipes 5 are located on a circle with a diameter smaller than the axial distance between the bottom suction ports of the two submersible pumps 20. Several nozzles 50 are opened at the bottom of the inner section and on both sides of the inner section of each cleaning pipe 5 located in the inner cavity of the cofferdam 4.

[0028] The self-cleaning device for the LNG ship fuel tank collection well of the present invention, when the submersible pump 20 is working and when the ship's power system (main engine and generator) is not working, LNG simultaneously flows back to the bottom injection pipe 1 through the LNG filling pipeline 101, and is then introduced into the collection well 10 through the connecting pipe 2, the annular return pipe 3 and four cleaning pipes 5. When the ship's power system is not in operation, i.e. during LNG recirculation, the impurities accumulated in the collection well 10 are dispersed by the combined action of the nozzles 50 of the four cleaning pipes 5 and the submersible pump 20. The dispersed impurities will gather around the collection well 10 and be blocked by the dike 4 to prevent them from accumulating directly below the bottom suction port of the submersible pump 20. At the same time, impurities flowing from the fuel tank 100 to the collection well 10 are also isolated by the dike 4 and will not enter the interior of the dike 4, i.e., will not accumulate directly below the submersible pump 20, thus preventing the suction port filter 21 of the submersible pump 20 from being blocked. This ensures the normal operation and safety of the submersible pump 20 and also facilitates subsequent cleaning by maintenance personnel.

[0029] The above embodiments are for illustrative purposes only and are not intended to limit the invention. Those skilled in the art can make various changes or modifications without departing from the spirit and scope of the invention. Therefore, all equivalent technical solutions should also fall within the scope of the invention and should be defined by the claims.

Claims

1. A self-cleaning device for a LNG carrier fuel tank sump, comprising a sump, a bottom injection pipe, an annular return pipe, a cofferdam, and several cleaning pipes; the sump is located at the bottom of the fuel tank, and two submersible pumps are vertically installed inside the fuel tank, with their bottom suction ports extending into the sump; the bottom injection pipe is horizontally located at the lower part of the fuel tank along its length and on one side of the sump, and its middle section is connected to the LNG refueling pipeline of the fuel tank; characterized in that, The annular return pipe is sleeved around the two submersible pumps and installed on the upper part of the collection well. The annular return pipe is connected to one end of the bottom injection pipe through an S-shaped connecting pipe. The cofferdam is coaxially fixed to the inner bottom surface of the liquid collection well with the annular return pipe. The cofferdam is a cylindrical body with an outer diameter smaller than the inner diameter of the liquid collection well but larger than the outer distance between the two submersible pumps. The height of the cofferdam is lower than the installation height of the annular return pipe. Several perforations are radially evenly distributed around the bottom circumference of the cofferdam. The cleaning pipe has a vertical section and a horizontal section and is L-shaped. The upper ends of the vertical sections of several cleaning pipes are evenly distributed around the annular return pipe. The horizontal sections of several cleaning pipes are inserted into several holes in the cofferdam in a corresponding manner. Several nozzles are opened at the bottom of the inner section and on both sides of the inner section of each cleaning pipe located in the inner cavity of the cofferdam.

2. The self-cleaning device for the LNG ship fuel tank collection well according to claim 1, characterized in that, The annular reflux pipe is fixed to the upper part of the inner wall of the liquid collection well by several supports.

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