Device for keeping stable operation of LNG (Liquefied Natural Gas) marine compressor

Abstract

The invention relates to the technical field of LNG (Liquefied Natural Gas) ships, in particular to a device for keeping stable operation of a compressor for an LNG ship. A device for keeping stable operation of a compressor for an LNG (liquefied natural gas) ship comprises a gas using end, a conveying pipeline for conveying gas is connected to the gas using end, the compressor is connected to the conveying pipeline, a buffer pipeline with the diameter larger than that of the conveying pipeline is further arranged on the conveying pipeline in series, and the buffer pipeline is bent and arranged in the ship. The internal volume of the gas using end is expanded through the buffer pipeline, so that the pressure change can be weakened conveniently when the gas amount in the gas using end changes; as the diameter of the buffer pipeline is larger than that of the conveying pipeline, the buffer pipeline has larger space as much as possible, the buffer effect is improved conveniently, and the problem that in the prior art, in order to weaken the influence of pressure change on the compressor when the pressure of the gas using end is changed, a buffer tank is arranged is solved. And the arrangement of the buffer tank on the LNG ship is limited due to the fact that the buffer tank generally has specific specifications and dimensions.

Description

Technical Field

[0001] The present invention relates to the technical field of LNG ships, and in particular to a device for maintaining stable operation of an LNG ship compressor. Background Art

[0002] LNG carriers, or liquefied natural gas carriers, are primarily used to safely transport liquefied natural gas (LNG) under cryogenic conditions. LNG carriers utilize LD compressors, which drive the entire gas-consuming system and serve as the primary pressure output unit. Natural gas is in a liquid state during transportation, but it undergoes a certain amount of natural evaporation, which can cause pressure in the pipelines storing it to rise. A sustained increase in pressure can be dangerous. LNG carriers also consume energy during navigation. Conventional technology typically uses this naturally evaporated natural gas to power the carrier's main engine.

[0003] The natural evaporation rate of natural gas is generally relatively constant, but the energy consumption of LNG ships under different operating conditions fluctuates greatly. When the ship's speed is fast and the onboard electricity consumption is high, the rate at which the LNG ship consumes natural gas may be greater than the natural evaporation rate of natural gas, which will lead to insufficient natural gas supply, thereby affecting the operation of the compressor. In severe cases, it will cause the equipment to be overloaded or overloaded, or even cause a shutdown. This will then reduce the amount of gas at the gas-consuming end on the ship, and correspondingly reduce the pressure at the gas-consuming end, thereby affecting the operation of the compressor. In severe cases, it will cause the equipment to be overloaded or overloaded, or even cause a shutdown. When the ship's speed is slow and the onboard electricity consumption is low, the rate at which the LNG ship consumes natural gas may be less than the natural evaporation rate of natural gas. At this time, the excess natural gas needs to be processed, usually by discharging it through the vent mast or burning it through the GCU (Gas Combustion Unit). In addition, frequent pressure fluctuations will lead to increased equipment wear and tear, affecting its service life.

[0004] To address these technical challenges, existing technologies typically employ a buffer tank approach. Specifically, buffer tanks are connected in series to the natural gas system. This arrangement slows down changes in natural gas volume and allows for storage of some natural gas for use when the LNG carrier consumes it more quickly. However, the use of buffer tanks increases costs, and buffer tanks are typically commercially available, with specific specifications. The space reserved onboard an LNG carrier may not be sufficient for their placement, making their deployment inflexible. Summary of the Invention

[0005] In view of this, the present invention provides a device for maintaining the smooth operation of an LNG ship compressor, so as to solve the problem in the prior art that when facing pressure changes at the gas-consuming end, in order to weaken the impact of pressure changes on the compressor, a buffer tank is arranged, but since the buffer tank generally has specific specifications and sizes, its arrangement on the LNG ship is limited.

[0006] A device for maintaining smooth operation of an LNG ship compressor includes a gas-using end, a delivery pipeline for transporting gas connected to the gas-using end, a compressor connected to the delivery pipeline, a buffer pipeline with a diameter larger than the delivery pipeline arranged in series on the delivery pipeline, the buffer pipeline being bent and arranged in the ship, the buffer pipeline and the delivery pipeline being connected via a connecting joint, the buffer pipeline having an input port for receiving gas transported by an upstream delivery pipeline and an output port for delivering gas to a downstream delivery pipeline, an input joint being provided on the input port, and an output joint being provided on the output port, at least one of the input joint and the output joint being a reducing joint, the reducing joint comprising a small-diameter interface for connecting to the delivery pipeline and a large-diameter interface for connecting to the buffer pipe.

[0007] Furthermore, the input connector is a reducing connector, the output connector is a tee connector, and the buffer pipe includes a main body section located between the input connector and the output connector and an extension section located at one end of the output connector away from the input connector.

[0008] Furthermore, one end of the extension section away from the output connector has a sealing plate for closing the extension section.

[0009] Furthermore, the buffer pipe is made of stainless steel.

[0010] The beneficial effects of the device for maintaining smooth operation of LNG ship compressors in the present invention are: the present invention improves the gas-using end on the LNG ship, and the gas-using end includes a delivery pipeline for gas delivery. In addition, a buffer pipeline is arranged in series on the delivery pipeline, and the internal volume of the gas-using end is expanded by the buffer pipeline, which is convenient for weakening the pressure change when the gas amount in the gas-using end changes; since the diameter of the buffer pipeline is larger than the diameter of the delivery pipeline, the buffer pipeline has as much space as possible, which is convenient for improving the buffering effect. Since it is the buffer pipeline that plays a buffering role, the layout of the pipeline can be changed according to the actual space or demand, which improves the flexibility of the layout, and thus solves the problem in the prior art that in order to weaken the impact of pressure changes on the compressor when facing pressure changes at the gas-using end, a buffer tank is arranged, and the buffer tank generally has specific specifications and sizes, which leads to limited layout on LNG ships. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0012] Figure 1 This is a schematic structural diagram of an embodiment of a device for maintaining stable operation of an LNG marine compressor according to the present invention;

[0013] Figure 2 for Figure 1 Schematic diagram of the structure of the medium reducer;

[0014] Figure 3 It is a structural schematic diagram of an embodiment of the device for maintaining stable operation of an LNG marine compressor in the present invention.

[0015] The meanings of the numbers in the figure are: 1. Buffer pipe; 2. Reducer; 3. First delivery pipe; 4. Second delivery pipe; 5. Compressor; 6. Mounting bracket; 7. Tee joint. DETAILED DESCRIPTION

[0016] To make the objectives, technical solutions, and advantages of the present invention more clearly apparent, the present invention is described below using specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are merely illustrative and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present invention.

[0017] The terms used in this disclosure are for the purpose of describing specific embodiments only and are not intended to limit the disclosure. As used in this disclosure and the appended claims, the singular forms "a," "an," "the," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and / or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

[0018] It should be understood that although the terms first, second, third, etc. may be used in this disclosure to describe various information, such information should not be limited to these terms and should not be understood to indicate or imply relative importance. These terms are only used to distinguish information of the same type from each other. For example, first information may also be referred to as second information, and similarly, second information may also be referred to as first information without departing from the scope of this disclosure. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining."

[0019] In the description of the present invention, it should be understood that the terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0020] In the description of the present invention, unless otherwise specified and limited, it should be noted that the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a mechanical connection or an electrical connection, or it can be the internal communication between two components. It can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to the specific circumstances.

[0021] In the following description, the suffixes such as "module", "component" or "unit" used to represent elements are only used to facilitate the description of the present invention and have no specific meaning. Therefore, "module" and "component" can be used interchangeably.

[0022] In order to better understand the technical solution of the present invention, the present invention is described in detail below with reference to the accompanying drawings.

[0023] In the embodiment 1 of the device for maintaining stable operation of the LNG marine compressor of the present invention (hereinafter referred to as the marine device):

[0024] like Figure 1 、 Figure 2 and Figure 3 As shown, the marine device in this embodiment includes a gas-using end arranged on an LNG ship. The gas-using end includes a delivery pipeline for transporting gas. The delivery pipeline is connected to a compressor 5. Through the action of the compressor 5, the gas is continuously transported out, which not only provides energy for the LNG ship but also consumes the naturally evaporated natural gas. Since the consumption of natural gas is often inconsistent with the natural evaporation of natural gas, in order to reduce the impact of the increase or decrease of natural gas in the gas-using end on the system and the compressor, a buffer pipeline 1 is also provided in this embodiment. The buffer pipeline 1 is connected in series with the transport pipeline, and the space inside it is interconnected. That is, the overall volume of the gas-using end is increased by the buffer pipeline 1. When the natural gas supply is less than the gas consumption, the pressure in the gas-using end decreases. Due to the increase in volume, the pressure change in the gas-using end will become smaller, thereby facilitating the protection of the system and the compressor. The buffer pipeline 1 is bent and arranged in the LNG ship through the mounting bracket 6. It can be arranged according to the specific space or structural characteristics, which is more flexible and convenient for customized design.

[0025] In this embodiment, the buffer pipe 1 is 316L low-temperature stainless steel, which has certain toughness and rigidity, and can also withstand high and low temperatures. Of course, in other embodiments, other materials can also be set according to actual needs. In order to achieve the connection between the buffer pipe 1 and the delivery pipeline, an input port for receiving the gas transported by the upstream delivery pipeline and an output port for delivering gas to the downstream delivery pipeline are provided on the buffer pipe 1. The delivery pipeline connected to the input port is recorded as the first delivery pipeline 3, and the delivery pipeline connected to the output port is recorded as the second delivery pipeline 4. The diameter of the buffer pipe 1 is larger than the diameter of the delivery pipeline, thereby increasing the space that the buffer pipe 1 can increase. In this embodiment, the buffer pipe 1 is DN750, and the diameter of the delivery pipeline is DN300. Of course, in other embodiments, the buffer pipe and the delivery pipeline can also be set to other sizes.

[0026] The buffer pipe 1 and the delivery pipe have different pipe diameters and need to be connected. The buffer pipe 1 and the delivery pipe are connected through a connecting joint. The connecting joint includes an input joint 2 located at the input port of the buffer pipe 1 and an output joint 7 located at the output port of the buffer pipe 1. In this embodiment, the input port is located at the end of one end of the buffer pipe 1. The input joint is a reducing joint, including a small-diameter interface for connecting to the delivery pipe and a large-diameter interface for connecting to the buffer pipe. The buffer pipe 1 and the delivery pipe are connected and sealed by the reducing joint. The output joint 7 is arranged in the middle of the buffer pipe 1. The output joint is a tee joint. The tee joint divides the buffer pipe 1 into a main section located between the input joint and the output joint and an extension section located at one end of the output joint away from the input joint. The tee joint has two interfaces of the same pipe diameter arranged relative to each other, which are used to connect to the main section and extension section of the buffer pipe 1 respectively. The other joint in the tee joint is connected to the input pipe. The end of the extension section away from the output joint 7 has a sealing plate for closing the extension section. The setting of the extension section allows the arrangement of an additional buffer pipe 1 without affecting the original output pipe setting. Of course, in other embodiments, the output port may be located at the other end of the buffer pipe away from the input port, in which case the joint needs to be adjusted adaptively. Alternatively, in other embodiments, the joint at the input port may be a tee joint, in which case an extension section is provided at the input port.

[0027] Specifically, in this embodiment, the mainstream is 174000m 3 Taking LNG carriers as an example, their natural evaporation rate does not exceed 0.1%. Relying solely on the natural evaporation of the cargo hold, their flow rate is approximately 3081.25 kg / h. Three operating conditions are set for gas consumption, as shown in Table 1.

[0028] Table 1 Different operating conditions and gas consumption

[0029]

[0030] Main engine gas consumption: 100% gas mode (1845.186 kg / h per engine) and 85% gas mode (1549.424 kg / h per engine). Generator gas consumption: 100% gas mode (571.67 kg / h per eight cylinders) and 85% gas mode (495.06 kg / h per eight cylinders) and 75% gas mode (449.41 kg / h per eight cylinders). During normal navigation, the main engine and generator typically do not operate at 100% gas mode. 75% and 85% gas modes represent the majority of operating conditions during navigation. Therefore, this calculation uses the main engine at 85% gas mode and the generator at 75% gas mode for analysis, providing general applicability.

[0031] Table 2 Calculation results of gas consumption under different working conditions

[0032] Calculation conditions Gas consumption Supply Is the supply sufficient? Working condition 1 1998.834kg / h 3081.25kg / h yes Working condition 2 2044.484kg / h 3081.25kg / h yes Working condition 3 3997.668kg / h 3081.25kg / h no

[0033] Table 2 can be obtained through calculation. The gas consumption is different under different working conditions. The above three working conditions are all working conditions that may occur during the navigation of LNG ships. By comparing the gas consumption and supply, it can be seen that the gas consumption is only met in working conditions 1 and 2. Under working condition 3, since the gas consumption is greater than the supply, it is extremely important to set up a buffer pipeline to weaken the pressure change at the gas end and thus ensure stable operation of the compressor.

[0034] It should be understood that the embodiments described are only a portion of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

Claims

1. A device for maintaining stable operation of an LNG marine compressor, comprising a gas-using end connected to a gas delivery pipeline, which is connected to a compressor, characterized in that: A buffer pipe with a diameter larger than that of the delivery pipe is also arranged in series on the delivery pipe. The buffer pipe is bent and arranged in the ship. The buffer pipe is connected to the delivery pipe via a connecting joint. The buffer pipe has an input port for receiving gas transported by the upstream delivery pipe and an output port for delivering gas to the downstream delivery pipe. The input port is provided with an input joint, and the output port is provided with an output joint. At least one of the input joint and the output joint is a reducing joint, and the reducing joint includes a small-diameter interface for connecting to the delivery pipe and a large-diameter interface for connecting to the buffer pipe.

2. The device for maintaining stable operation of an LNG marine compressor according to claim 1, characterized in that: The input joint is a reducing joint, the output joint is a tee joint, and the buffer pipe includes a main section located between the input joint and the output joint and an extension section located at one end of the output joint away from the input joint.

3. The device for maintaining stable operation of an LNG marine compressor according to claim 2, characterized in that: One end of the extension section away from the output connector is provided with a sealing plate for closing the extension section.

4. The device for maintaining stable operation of an LNG marine compressor according to any one of claims 1 to 3, characterized in that: The buffer pipe is made of stainless steel.

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