A ship unloading system for LNG and LPG using a common unloading boom

Abstract

The application discloses an LNG and LPG shared unloading arm unloading system, which comprises an unloading arm assembly, a matched header assembly and a supporting system, wherein the unloading arm assembly comprises an unloading liquid phase arm assembly and an unloading gas phase arm; the unloading liquid phase arm assembly comprises an unloading gas / liquid phase arm and a first unloading liquid phase arm and a second unloading liquid phase arm; the matched header assembly comprises an unloading liquid phase branch pipe assembly, an unloading liquid phase header, an unloading gas phase pipeline, an LNG unloading liquid phase pipeline, an LPG unloading liquid phase pipeline, an LNG unloading gas phase branch pipe and an LPG unloading gas phase branch pipe; and the unloading liquid phase branch pipe assembly comprises a first unloading liquid phase branch pipe, a second unloading liquid phase branch pipe and a third unloading liquid phase branch pipe. When facing an LNG ship or an LPG ship, the application can realize sharing of one set of unloading arm assembly by switching corresponding pipelines in the matched header assembly, and can transport independently unloaded LNG or LPG to a corresponding LNG storage system or LPG storage system for storage, so that the cost is reduced, the operation process is simplified and the stability of factory operation is improved.

Description

Technical Field

[0001] This invention relates to the field of petrochemical technology, and in particular to an unloading system for LNG and LPG using a shared unloading arm. Background Technology

[0002] LNG (liquefied natural gas) is a widely used high-quality energy source. Due to its high calorific value, high efficiency, and low pollution, LNG is widely used in various sectors of the national economy and people's livelihood, and its share of energy consumption is gradually increasing. Unloading vessels are the main source of products for LNG receiving terminals. Through unloading arms and unloading manifolds, LNG from transport ships is transferred to LNG storage tanks for storage, thereby enabling the receiving terminal to perform peak-shaving functions.

[0003] LPG (liquefied petroleum gas) is an important raw material for many chemical products. Atmospheric pressure cryogenic storage tanks are an important means of storing LPG. Unloading arms are also required to transport LPG from transport ships to LPG storage tanks.

[0004] With the development of the energy and chemical industries, the functions and product types of chemical plants and LNG receiving terminals are gradually increasing, and the required raw materials are also growing. The demand for plants to simultaneously handle LNG and LPG unloading and storage will gradually increase. If the current process is followed, two unloading systems need to be set up to handle LNG and LPG unloading operations separately. This not only increases investment in terminal space, the number of unloading arm equipment, and piping, but also makes the process more complex and adversely affects operations during operation.

[0005] Based on the above background, the present invention provides an unloading system for LNG and LPG using a shared unloading arm, which not only saves investment in projects such as terminals and equipment, but also simplifies the operation process and improves the stability of plant operation. Summary of the Invention

[0006] In view of the above problems, the present invention is proposed to provide an unloading system for LNG and LPG using a shared unloading arm that overcomes or at least partially solves the above problems.

[0007] This invention provides an unloading system for LNG and LPG using a shared unloading arm, the system comprising:

[0008] The unloading arm assembly includes an unloading liquid phase arm assembly and an unloading gas phase arm assembly. The unloading liquid phase arm assembly includes unloading gas / liquid phase arms, a first unloading liquid phase arm, and a second unloading liquid phase arm arranged in parallel.

[0009] The supporting main pipeline assembly includes an unloading liquid phase branch pipe assembly, an unloading liquid phase main pipe, an unloading gas phase pipeline, an LNG unloading liquid phase pipeline, an LPG unloading liquid phase pipeline, an LNG unloading gas phase branch pipe, and an LPG unloading gas phase branch pipe. The unloading liquid phase branch pipe assembly includes a first unloading liquid phase branch pipe, a second unloading liquid phase branch pipe, and a third unloading liquid phase branch pipe. An LNG unloading liquid phase shut-off valve is installed on the LNG unloading liquid phase pipeline, an LPG unloading liquid phase shut-off valve is installed on the LPG unloading liquid phase pipeline, an LNG unloading gas phase shut-off valve is installed on the LNG unloading gas phase branch pipe, and an LPG unloading gas phase shut-off valve is installed on the LPG unloading gas phase branch pipe.

[0010] LNG storage system, used to store LNG;

[0011] LPG storage system for storing LPG;

[0012] The first unloading liquid phase arm is connected to the unloading liquid phase main pipe via a first unloading liquid phase branch pipe; the second unloading liquid phase arm is connected to the unloading liquid phase main pipe via a second unloading liquid phase branch pipe; the unloading gas / liquid phase arm is connected to the unloading liquid phase main pipe and the unloading gas phase pipeline via a third unloading liquid phase branch pipe; the unloading gas phase arm is connected to the LPG unloading gas phase branch pipe via the unloading gas phase pipeline, and the LPG unloading gas phase branch pipe is connected to the LPG storage system; the unloading liquid phase main pipe is connected to the LNG storage system via the LNG unloading liquid phase pipeline, and the unloading liquid phase main pipe is connected to the LPG storage system via the LPG unloading liquid phase pipeline; the LNG unloading gas phase branch pipe is connected between the LNG storage system and the unloading gas phase pipeline.

[0013] Optionally, the LNG storage system is connected to an LNG unloading cold circulation pipeline, which is connected to the unloading liquid phase main pipe via an LNG-to-shared unloading main pipe cold circulation pipeline. The LNG unloading cold circulation pipeline is equipped with an LNG cold circulation shut-off valve and an LNG unloading cold circulation manual valve.

[0014] Optionally, the LPG storage system is connected to an LPG unloading cold circulation pipeline, which is connected to the unloading liquid phase main pipe via an LPG shared unloading main pipe cold circulation pipeline. The LPG unloading cold circulation pipeline is equipped with an LPG cold circulation shut-off valve and an LPG unloading cold circulation manual valve.

[0015] Optionally, a first nitrogen purging line is provided at the connection between the first unloading liquid phase branch pipe and the first unloading liquid phase arm, and a first temperature sensor, a first pressure sensor and a first shut-off valve for the unloading liquid phase branch pipe are respectively provided on the first unloading liquid phase branch pipe.

[0016] Optionally, a second nitrogen purging line is provided at the connection between the second unloading liquid phase branch pipe and the second unloading liquid phase arm, and a second temperature sensor, a second pressure sensor, and a second shut-off valve for the unloading liquid phase branch pipe are respectively provided on the second unloading liquid phase branch pipe.

[0017] Optionally, a third nitrogen purging line is provided at the connection between the third unloading liquid phase branch pipe and the unloading gas / liquid phase arm, and a third temperature sensor, a third pressure sensor, and a third shut-off valve for the unloading liquid phase branch pipe are respectively provided on the third unloading liquid phase branch pipe.

[0018] Optionally, a fourth nitrogen purging line is provided at the connection between the unloading gas phase pipeline and the unloading gas phase arm, a fourth temperature sensor and a fourth pressure sensor are respectively provided on the unloading gas phase pipeline, and an LPG unloading gas phase shut-off valve is provided on the LPG unloading gas phase branch pipe.

[0019] Optionally, the unloading gas phase pipeline is also equipped with an unloading return gas pressure regulating valve, and a fifth pressure sensor is connected to both ends of the unloading return gas pressure regulating valve.

[0020] Optionally, an LNG unloading main drain line is connected to the LNG unloading liquid phase pipeline, and the other end of the LNG unloading main drain line is connected to the unloading liquid phase main pipeline. An LNG unloading drain valve is installed on the LNG unloading main drain line.

[0021] Optionally, an LPG unloading liquid phase pipeline is connected to the LPG unloading main drain pipeline, the other end of the LPG unloading main drain pipeline is connected to the unloading liquid phase main pipeline, and an LPG unloading drain valve is installed on the LPG unloading main drain pipeline.

[0022] The technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:

[0023] The LNG and LPG shared unloading arm unloading system described in this embodiment of the invention, when facing LNG or LPG ships, achieves the sharing of a single unloading arm assembly by switching the corresponding pipelines within the matching main pipe assembly. This allows the independently unloaded LNG or LPG to be transported to the corresponding LNG storage system or LPG storage system for storage, which not only reduces costs but also simplifies the operation process and improves the stability of plant operation.

[0024] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0025] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings.

[0026] In the attached diagram:

[0027] Figure 1 This is a schematic diagram of the principle structure of an unloading system for LNG and LPG sharing an unloading arm, provided in an embodiment of the present invention.

[0028] Explanation of reference numerals in the attached figures:

[0029] L01A - First unloading liquid phase arm; L01B - Unloading gas / liquid phase arm; L01C - Second unloading liquid phase arm; L02 - Unloading gas phase arm; S01A - First unloading liquid phase branch pipe; S01B - Third unloading liquid phase branch pipe; S01C - Second unloading liquid phase branch pipe; S02 - Unloading gas phase pipeline; S03 - Unloading liquid phase main pipe; S11 - LNG unloading liquid phase pipeline; S12 - LNG unloading gas phase branch pipe; S13 - LNG unloading cold circulation pipeline; S1 4 - LNG to common unloading main cold circulation pipeline; S15 - LNG unloading main drain pipeline; S21 - LPG unloading liquid phase pipeline; S22 - LPG unloading gas phase branch pipeline; S23 - LPG unloading cold circulation pipeline; S24 - LPG to common unloading main cold circulation pipeline; S25 - LPG unloading main drain pipeline; XV1 - First shut-off valve of unloading liquid phase branch pipeline; XV2 - Third shut-off valve of unloading liquid phase branch pipeline; XV3 - Second shut-off valve of unloading liquid phase branch pipeline. Shut-off valves; XV4 - LNG unloading liquid phase shut-off valve; XV5 - LPG unloading liquid phase shut-off valve; XV6 - LNG unloading gas phase shut-off valve; XV7 - LPG unloading gas phase shut-off valve; XV8 - LNG cold cycle shut-off valve; XV9 - LPG cold cycle shut-off valve; XV10 - First nitrogen purging line; XV11 - Third nitrogen purging line; XV12 - Second nitrogen purging line; XV13 - Fourth nitrogen purging line; MV1 - LNG unloading purging line Valves; MV2 - LPG unloading drain valve; MV3 - LNG unloading cold circulation manual valve; MV4 - LPG unloading cold circulation manual valve; PCV1 - unloading return gas pressure regulating valve; P1 - first pressure sensor; P2 - second pressure sensor; P3 - third pressure sensor; P4 - fourth pressure sensor; P5 - fifth pressure sensor; T1 - first temperature sensor; T2 - second temperature sensor; T3 - third temperature sensor; T4 - fourth temperature sensor. Detailed Implementation

[0030] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings.

[0031] The accompanying drawings illustrate various structural schematics according to embodiments of the present disclosure. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0032] In the context of this disclosure, when a layer / component is referred to as being "above" another layer / component, that layer / component may be directly above the other layer / component, or there may be an intermediate layer / component between them. Additionally, if a layer / component is "above" another layer / component in one orientation, then when the orientation is reversed, that layer / component may be "below" the other layer / component. In the context of this disclosure, similar or identical components may be denoted by the same or similar reference numerals.

[0033] To better understand the above technical solutions, the following will describe the above technical solutions in detail with reference to specific implementation methods. It should be understood that the embodiments of this disclosure and the specific features in the embodiments are detailed descriptions of the technical solutions of this application, rather than limitations on the technical solutions of this application. In the absence of conflict, the embodiments of this application and the technical features in the embodiments can be combined with each other.

[0034] Figure 1 This is a flowchart of an unloading system for LNG and LPG using a shared unloading arm, provided by an embodiment of the present invention. Figure 1 As shown, the unloading system for LNG and LPG sharing an unloading arm includes: an unloading arm assembly, a supporting main pipe assembly, an LNG storage system, and an LPG storage system. The unloading arm assembly includes an unloading liquid phase arm assembly and an unloading gas phase arm L02. The unloading liquid phase arm assembly includes a parallel unloading gas / liquid phase arm L01B, a first unloading liquid phase arm L01A, and a second unloading liquid phase arm L01C. The supporting main pipe assembly includes an unloading liquid phase branch pipe assembly, an unloading liquid phase main pipe S03, an unloading gas phase pipeline S02, an LNG unloading liquid phase pipeline S11, and an LPG unloading liquid phase pipeline S21. The unloading liquid phase branch pipe assembly includes a first unloading liquid phase branch pipe S01A, a second unloading liquid phase branch pipe S01C, and a third unloading liquid phase branch pipe S01B. The LNG storage system is used to store LNG; the LPG storage system is used to store LPG.

[0035] Specifically, the first unloading liquid phase arm L01A is connected to the unloading liquid phase main pipe S03 via the first unloading liquid phase branch pipe S01A; the second unloading liquid phase arm L01C is connected to the unloading liquid phase main pipe S03 via the second unloading liquid phase branch pipe S01C; the unloading gas / liquid phase arm L01B is connected to the unloading liquid phase main pipe S03 and the unloading gas phase pipeline S02 via the third unloading liquid phase branch pipe S01B; the unloading gas phase arm L02 is connected to the LPG unloading gas phase branch pipe S22 via the unloading gas phase pipeline S02, and the LPG unloading gas phase branch pipe S22 is connected to the LPG storage system; the unloading liquid phase main pipe S03 is connected to the LNG storage system via the LNG unloading liquid phase pipeline S11, and the unloading liquid phase main pipe S03 is connected to the LPG storage system via the LPG unloading liquid phase pipeline S21.

[0036] Optionally, an LNG unloading vapor phase branch pipe S12 is connected between the LNG storage system and the unloading vapor phase pipeline S02. An LNG unloading vapor phase shut-off valve XV6 is installed on the LNG unloading vapor phase branch pipe S12 to control the on / off state of the LNG unloading vapor phase branch pipe S12. An LPG unloading vapor phase shut-off valve XV7 is installed on the LPG unloading vapor phase branch pipe S22. 7 is used to control the on / off state of the LPG unloading gas phase branch pipe S22; an LNG unloading liquid phase shut-off valve XV4 is installed on the LNG unloading liquid phase pipeline S11, and the LNG unloading liquid phase shut-off valve XV4 is used to control the on / off state of the LNG unloading liquid phase pipeline S11; an LPG unloading liquid phase shut-off valve XV5 is installed on the LPG unloading liquid phase pipeline S21, and the LPG unloading liquid phase shut-off valve XV5 is used to control the on / off state of the LPG unloading liquid phase pipeline S21.

[0037] The LNG and LPG shared unloading arm unloading system described in this embodiment of the invention, when facing LNG or LPG ships, achieves the sharing of a single unloading arm assembly by switching the corresponding pipelines within the matching main pipe assembly. This allows the independently unloaded LNG or LPG to be transported to the corresponding LNG storage system or LPG storage system for storage. This not only saves on investment in terminals, equipment, and other projects and reduces costs, but also simplifies the operation process and improves the stability of plant operation.

[0038] Before an LNG or LPG vessel docks, existing LNG or LPG can be used to circulate cold circulation through pipelines to maintain a cold state. Optionally, the LNG storage system is connected to an LNG unloading cold circulation pipeline S13, which is connected to the unloading liquid phase main pipe S03 via an LNG-to-shared unloading main pipe cold circulation pipeline S14. The LNG unloading cold circulation pipeline S13 is equipped with an LNG cold circulation shut-off valve XV8 and an LNG unloading cold circulation manual valve MV3. Similarly, the LPG storage system is connected to an LPG unloading cold circulation pipeline S23, which is connected to the unloading liquid phase main pipe S03 via an LPG-to-shared unloading main pipe cold circulation pipeline S24. The LPG unloading cold circulation pipeline S23 is equipped with an LPG cold circulation shut-off valve XV9 and an LPG unloading cold circulation manual valve MV4. In this embodiment of the invention, by setting up an LNG unloading cold circulation pipeline S13 and an LPG unloading cold circulation pipeline S23, the unloading liquid phase main pipe S03 is connected to the LNG storage system and the LPG storage system respectively. This allows the stored LNG or LPG to be used to circulate cold through the system pipelines to maintain a cold state. At the same time, corresponding valves are set up to control the opening or closing of the corresponding pipelines to achieve flexible line switching.

[0039] After the LNG or LPG unloading operation is completed, in order to purge and drain the pipeline, this embodiment of the invention also includes corresponding nitrogen purging pipelines and purge pipelines, specifically:

[0040] A first nitrogen purging line XV10 is installed at the connection between the first unloading liquid phase branch pipe S01A and the first unloading liquid phase arm L01A. A first temperature sensor T1, a first pressure sensor P1, and a first shut-off valve XV1 are respectively installed on the first unloading liquid phase branch pipe S01A. The first nitrogen purging line XV10 is used to purge residual LNG at the connection between the first unloading liquid phase branch pipe S01A and the first unloading liquid phase arm L01A. The first temperature sensor T1 and the first pressure sensor P1 are used to detect the temperature and pressure within the first unloading liquid phase branch pipe S01A, respectively. The first shut-off valve XV1 is used to control the on / off state of the first unloading liquid phase branch pipe S01A.

[0041] A second nitrogen purging line XV12 is installed at the connection between the second unloading liquid phase branch S01C and the second unloading liquid phase arm L01C. A second temperature sensor T2, a second pressure sensor P2, and a second shut-off valve XV3 are respectively installed on the second unloading liquid phase branch S01C. The second nitrogen purging line XV12 is used to purge residual LNG at the connection between the second unloading liquid phase branch S01C and the second unloading liquid phase arm L01C. The second temperature sensor T2 and the second pressure sensor P2 are used to detect the temperature and pressure within the second unloading liquid phase branch S01C, respectively. The second shut-off valve XV3 is used to control the on / off state of the second unloading liquid phase branch S01C.

[0042] A third nitrogen purging line XV11 is installed at the connection between the third unloading liquid phase branch S01B and the unloading gas / liquid phase arm L01B. A third temperature sensor T3, a third pressure sensor P3, and a third shut-off valve XV2 are respectively installed on the third unloading liquid phase branch S01B. The third nitrogen purging line XV11 is used to purge residual LNG or LPG at the connection between the third unloading liquid phase branch S01B and the unloading gas / liquid phase arm L01B. The third temperature sensor T3 and the third pressure sensor P3 are used to detect the temperature and pressure within the third unloading liquid phase branch S01B, respectively. The third shut-off valve XV2 is used to control the on / off state of the third unloading liquid phase branch S01B.

[0043] A fourth nitrogen purging line XV13 is installed at the connection between the unloading gas phase pipeline S02 and the unloading gas phase arm L02. A fourth temperature sensor T4 and a fourth pressure sensor P4 are respectively installed on the unloading gas phase pipeline S02. An LPG unloading gas phase shut-off valve XV7 is installed on the LPG unloading gas phase branch pipe S22. An unloading return gas pressure regulating valve PCV1 is also installed on the unloading gas phase pipeline S02, and a fifth pressure sensor P5 is connected to both ends of the unloading return gas pressure regulating valve PCV1. The fourth nitrogen purging line XV13 is used to purge the residual LPG at the connection between the unloading gas phase line S02 and the unloading gas phase arm L02. The fourth temperature sensor T4 and the fourth pressure sensor P4 are used to detect the temperature and pressure in the fourth unloading liquid phase branch pipe, respectively. The LPG unloading gas phase shut-off valve XV7 is used to control the opening and closing of the LPG unloading gas phase branch pipe S22. The unloading return gas pressure regulating valve PCV1 is used to control the opening and closing of the unloading gas phase line S02.

[0044] An LNG unloading liquid phase pipeline S11 is connected to an LNG unloading main drain pipeline S15, the other end of which is connected to the unloading liquid phase main pipeline S03. An LNG unloading drain valve MV1 is installed on the LNG unloading main drain pipeline S15. The LNG unloading main drain pipeline S15 is used to drain the residual LNG from the LNG unloading liquid phase pipeline S11 into the unloading liquid phase main pipeline S03. The LNG unloading drain valve MV1 is used to control the on / off state of the LNG unloading main drain pipeline S15.

[0045] The LPG unloading liquid phase pipeline S21 is connected to an LPG unloading main drain pipeline S25, the other end of which is connected to the unloading liquid phase main pipeline S03. An LPG unloading drain valve MV2 is installed on the LPG unloading main drain pipeline S25. The LPG unloading main drain pipeline S25 is used to drain the residual LPG from the LPG unloading liquid phase pipeline S21 into the unloading liquid phase main pipeline S03. The LPG unloading drain valve MV2 is used to control the on / off state of the LPG unloading main drain pipeline S25.

[0046] In this embodiment of the invention, the LNG unloading liquid phase pipeline S11 and the LNG unloading cold circulation pipeline S13 are connected. The two connection points of this passage are located after the LNG unloading liquid phase shut-off valve XV4 on the LNG unloading liquid phase pipeline S11 and before the LNG cold circulation shut-off valve XV8 on the LNG unloading cold circulation pipeline S13, respectively.

[0047] In this embodiment of the invention, the LPG unloading liquid phase pipeline S21 and the LPG unloading cold circulation pipeline S23 are connected. The two connection points of this passage are respectively located after the LPG unloading liquid phase shut-off valve XV5 on the LPG unloading liquid phase pipeline S21, and between the LPG unloading cold circulation manual valve and the LPG cold circulation shut-off valve on the LPG unloading cold circulation pipeline S23.

[0048] The working principle of the unloading system for LNG and LPG sharing an unloading arm described in this embodiment of the invention is as follows:

[0049] Before the arrival of LNG or LPG ships, this embodiment of the invention uses LNG or LPG for cold circulation operation through the unloading liquid phase main S03. At this time, the first shut-off valve XV1, the second shut-off valve XV3, the third shut-off valve XV2, the unloading return gas pressure regulating valve PCV1, the LNG unloading gas phase shut-off valve XV6, the LPG unloading gas phase shut-off valve XV7, the first nitrogen purging line XV10, the third nitrogen purging line XV11, the second nitrogen purging line XV12, and the fourth nitrogen purging line XV13 are all in the closed state.

[0050] When LNG is used for cold circulation operation, the LNG cold circulation shut-off valve XV8, the LNG unloading cold circulation manual valve MV3, and the LNG unloading liquid phase shut-off valve XV4 are in the open state, and the LNG unloading drain valve MV1 is closed. The LNG flow is as follows: LNG storage system → LNG unloading cold circulation pipeline S13 → LNG to common unloading main pipeline cold circulation pipeline S14 → unloading liquid phase main pipeline S03 → LNG unloading liquid phase pipeline S11 → LNG storage system. The LPG cold circulation shut-off valve XV9 is open, and the LPG unloading cold circulation manual valve MV4, the LPG unloading liquid phase shut-off valve XV5, and the LPG unloading drain valve MV2 are all closed. The LPG flow is as follows: LPG storage system → LPG unloading cold circulation pipeline S23 → LPG unloading liquid phase pipeline S21 → LPG storage system.

[0051] When LPG is used for cold circulation operation, the LPG cold circulation shut-off valve XV9, LPG unloading cold circulation manual valve MV4, and LPG unloading liquid phase shut-off valve XV5 are in the open state, and the LPG unloading drain valve MV2 is closed. The LPG route is: LPG storage system → LPG unloading cold circulation pipeline S23 → LPG to shared unloading main pipeline cold circulation pipeline S24 → unloading liquid phase main pipeline S03 → LPG unloading liquid phase pipeline S21 → LPG storage system. The LNG cold circulation shut-off valve XV8 is open, and the LNG unloading liquid phase shut-off valve XV4, LNG unloading drain valve MV1, and LNG unloading cold circulation manual valve MV3 are closed. The LNG route is: LNG storage system → LNG unloading cold circulation pipeline S13 → LNG unloading liquid phase pipeline S11 → LNG storage system.

[0052] When the LNG carrier docks, this embodiment of the invention first shuts off the cooling cycle, then connects the first unloading liquid phase arm L01A, the unloading gas / liquid phase arm L01B, the second unloading liquid phase arm L01C, and the unloading gas phase arm L02 to the LNG carrier respectively. The first shut-off valve XV1, the second shut-off valve XV3, the third shut-off valve XV2, the LNG unloading liquid phase shut-off valve XV4, and the LNG unloading gas phase shut-off valve XV6 are then opened, and the unloading return gas pressure regulating valve PCV1 is engaged. With automatic control enabled and all other valves closed, LNG is unloaded via the following process: first unloading liquid phase arm L01A / unloading gas / liquid phase arm L01B / second unloading liquid phase arm L01C → unloading liquid phase main pipe S03 → LNG unloading liquid phase pipeline S11 → LNG storage system. BOG (BOG is flash vapor, i.e., the gas produced after LNG evaporation and vaporization) from the LNG storage system returns to the LNG ship via LNG unloading gas phase branch pipe S12 → unloading gas phase pipeline S02 → unloading gas phase arm L02. After unloading is completed, open the first nitrogen purging line XV10, the third nitrogen purging line XV11, and the second nitrogen purging line XV12 to purge the residual LNG in the first unloading liquid phase branch pipe S01A, the third unloading liquid phase branch pipe S01B, and the second unloading liquid phase branch pipe S01C to the unloading liquid phase main pipe S03. Disconnect the LNG ship from the first unloading liquid phase arm L01A, the unloading gas / liquid phase arm L01B, the second unloading liquid phase arm L01C, and the unloading gas phase arm L02.

[0053] When the LPG vessel docks, this embodiment of the invention first shuts off the cooling cycle, then connects the first unloading liquid phase arm L01A, the unloading gas / liquid phase arm L01B, the second unloading liquid phase arm L01C, and the unloading gas phase arm L02 to the LPG vessel, respectively. The first shut-off valve XV1, the second shut-off valve XV3, the third shut-off valve XV2, the LPG unloading liquid phase shut-off valve XV5, and the LPG unloading gas phase shut-off valve XV7 are then opened, and the unloading process begins. The gas pressure regulating valve PCV1 is put into automatic control, and all other valves are in the closed state. LPG is unloaded from the ship via the first unloading liquid phase branch pipe S01A / the third unloading liquid phase branch pipe S01B / the second unloading liquid phase branch pipe S01C → unloading liquid phase main pipe S03 → LPG unloading liquid phase pipeline S21 → LPG storage system. BOG from the LPG storage system returns to the LPG ship via the LPG unloading gas phase branch pipe S22 → unloading gas phase pipeline S02 → unloading gas phase arm L02. After unloading is completed, open the first nitrogen purging line XV10, the third nitrogen purging line XV11, and the second nitrogen purging line XV12 to purge the residual LPG in the first unloading liquid phase branch S01A, the third unloading liquid phase branch S01B, and the second unloading liquid phase branch S01C to the unloading liquid phase main S03. Disconnect the LPG vessel from the first unloading liquid phase arm L01A, the unloading gas / liquid phase arm L01B, the second unloading liquid phase arm L01C, and the unloading gas phase arm L02.

[0054] The LNG and LPG shared unloading arm unloading system described in this embodiment of the invention has the following advantages compared to the prior art:

[0055] 1. When dealing with LNG carriers or LPG carriers, by switching the corresponding pipelines in the matching main pipeline assembly, a single unloading arm assembly can be used to transport the independently unloaded LNG or LPG to the corresponding LNG storage system or LPG storage system for storage. This reduces costs, simplifies the operation process, and improves the stability of plant operation.

[0056] 2. Shut-off valves are installed on the unloading pipelines corresponding to LNG and LPG respectively to achieve independent unloading operations of LNG and LPG, thus avoiding the risk of LNG and LPG mixing;

[0057] 3. Corresponding unloading cold circulation pipelines are set up for the LNG unloading and LPG unloading processes respectively. By adjusting the valve status of different pipelines, the LNG unloading main pipe and LPG unloading main pipe can be kept cold by utilizing the existing LNG or LPG when not unloading.

[0058] 4. Corresponding drain and purge pipelines are installed on the LNG and LPG unloading pipelines respectively to facilitate the draining and purging of the LNG and LPG pipelines after the unloading operation is completed.

[0059] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0060] Similarly, it should be understood that, in order to simplify this disclosure and aid in understanding one or more of the various aspects of the invention, in the above description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof. However, this method of disclosure should not be construed as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as reflected in the following claims, inventive aspects lie in fewer than all features of a single foregoing disclosed embodiment. Therefore, the claims following the detailed description are hereby expressly incorporated into this detailed description, wherein each claim itself is a separate embodiment of the invention.

[0061] It should be noted that the above embodiments are illustrative of the invention and not restrictive of the invention, and that those skilled in the art can devise alternative embodiments without departing from the scope of the appended claims.

Claims

1. A system for unloading LNG and LPG using a common unloading arm, characterized in that, The LNG and LPG share the unloading system of the unloading arm, comprising: The unloading arm assembly comprises an unloading liquid phase arm assembly and an unloading gas phase arm, the unloading liquid phase arm assembly comprises a first unloading liquid phase arm, a second unloading liquid phase arm and a parallelly arranged unloading gas / liquid phase arm; The complete header assembly comprises an unloading liquid phase branch pipe assembly, an unloading liquid phase header, an unloading gas phase pipeline, an LNG unloading liquid phase pipeline, an LPG unloading liquid phase pipeline, an LNG unloading gas phase branch pipe and an LPG unloading gas phase branch pipe, the unloading liquid phase branch pipe assembly comprises a first unloading liquid phase branch pipe, a second unloading liquid phase branch pipe and a third unloading liquid phase branch pipe, wherein the LNG unloading liquid phase pipeline is provided with an LNG unloading liquid phase shut-off valve, the LPG unloading liquid phase pipeline is provided with an LPG unloading liquid phase shut-off valve, the LNG unloading gas phase branch pipe is provided with an LNG unloading gas phase shut-off valve, and the LPG unloading gas phase branch pipe is provided with an LPG unloading gas phase shut-off valve; An LNG storage system is arranged for storing LNG; An LPG storage system is arranged for storing LPG; The first unloading liquid phase arm is communicated with the unloading liquid phase header through the first unloading liquid phase branch pipe; the second unloading liquid phase arm is communicated with the unloading liquid phase header through the second unloading liquid phase branch pipe; the unloading gas / liquid phase arm is communicated with the unloading liquid phase header and the unloading gas phase pipeline through the third unloading liquid phase branch pipe; the unloading gas phase arm is communicated with the LPG unloading gas phase branch pipe through the unloading gas phase pipeline, and the LPG unloading gas phase branch pipe is communicated with the LPG storage system; the unloading liquid phase header is communicated with the LNG storage system through the LNG unloading liquid phase pipeline, and is communicated with the LPG storage system through the LPG unloading liquid phase pipeline; the LNG storage system and the unloading gas phase pipeline are communicated through the LNG unloading gas phase branch pipe.

2. The LNG and LPG co-use unloading arm unloading system according to claim 1, characterized in that, The LNG storage system is provided with an LNG unloading cold circulation pipeline, the LNG unloading cold circulation pipeline is communicated with the unloading liquid phase header through an LNG-to-common unloading header cold circulation pipeline, and the LNG unloading cold circulation pipeline is provided with an LNG cold circulation shut-off valve and an LNG unloading cold circulation hand valve.

3. The LNG and LPG co-use unloading arm unloading system according to claim 1, characterized in that, The LPG storage system is provided with an LPG unloading cold circulation pipeline, the LPG unloading cold circulation pipeline is communicated with the unloading liquid phase header through an LPG-to-common unloading header cold circulation pipeline, and the LPG unloading cold circulation pipeline is provided with an LPG cold circulation shut-off valve and an LPG unloading cold circulation hand valve.

4. The LNG and LPG co-use unloading arm unloading system according to claim 1, characterized in that, A first nitrogen purging pipeline is arranged at the connection between the first unloading liquid phase branch pipe and the first unloading liquid phase arm, and the first unloading liquid phase branch pipe is respectively provided with a first temperature sensor, a first pressure sensor and a first unloading liquid phase branch pipe shut-off valve.

5. The LNG and LPG co-use unloading arm unloading system according to claim 1, characterized in that, A second nitrogen purging pipeline is arranged at the connection between the second unloading liquid phase branch pipe and the second unloading liquid phase arm, and the second unloading liquid phase branch pipe is respectively provided with a second temperature sensor, a second pressure sensor and a second unloading liquid phase branch pipe shut-off valve.

6. The LNG and LPG co-use unloading arm unloading system according to claim 1, characterized in that, The third nitrogen blowing pipeline is arranged at the connection between the third unloading liquid phase branch pipe and the unloading gas / liquid phase arm, and the third unloading liquid phase branch pipe is respectively provided with a third temperature sensor, a third pressure sensor and a third unloading liquid phase branch pipe shut-off valve.

7. The LNG and LPG co-use unloading arm unloading system according to claim 1, characterized in that, The fourth nitrogen blowing pipeline is arranged at the connection between the unloading gas phase pipeline and the unloading gas phase arm, the unloading gas phase pipeline is respectively provided with a fourth temperature sensor and a fourth pressure sensor, and the LPG unloading gas phase branch pipe is provided with an LPG unloading gas phase shut-off valve.

8. The LNG and LPG co-use ship unloading arm ship unloading system according to claim 7, characterized in that, The unloading gas phase pipeline is further provided with an unloading return gas pressure regulating valve, and the two ends of the unloading return gas pressure regulating valve are connected and provided with a fifth pressure sensor.

9. The LNG and LPG co-use unloading arm unloading system according to claim 1, characterized in that, The LNG unloading liquid phase pipeline is communicated and provided with an LNG unloading main pipe purging pipeline, the other end of the LNG unloading main pipe purging pipeline is communicated with an unloading liquid phase main pipe, and the LNG unloading main pipe purging pipeline is provided with an LNG unloading purging valve.

10. The LNG and LPG co-use unloading arm unloading system according to claim 1, characterized in that, The LPG unloading liquid phase pipeline is communicated and provided with an LPG unloading main pipe purging pipeline, the other end of the LPG unloading main pipe purging pipeline is communicated with an unloading liquid phase main pipe, and the LPG unloading main pipe purging pipeline is provided with an LPG unloading purging valve.

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