Comprehensive process for improving safety of LNG (Liquefied Natural Gas) energy station

Abstract

The invention provides a comprehensive process for improving the safety of an LNG (Liquefied Natural Gas) energy station, which relates to the technical field of LNG and comprises an LNG storage tank anti-rolling process, a pressure stabilizing process, a propane discharge pretreatment and recovery process, a storage tank separation process and a plate type indirect heat exchange process. According to the anti-rolling process for the LNG storage tank, LNG in the storage tank is stirred, so that the temperature difference and the density difference of adjacent layers are reduced, and the rolling phenomenon is prevented; the pressure stabilizing process can ensure the stability of the inlet pressure of the LNG high-pressure pump; according to the propane discharge pretreatment recovery process, gaseous propane is liquefied into liquid propane, and the gaseous propane entering a storage tank BOG system is reduced; the storage tank is divided into at least two parts which are respectively filled with media by the storage tank separation process, so that the utilization efficiency of equipment is improved; according to the plate type indirect heat exchange process, heat between high-pressure LNG and circulating water is transferred through an intermediate medium in a heat exchange plate. The technical effect of comprehensively improving the stability, the safety and the equipment utilization rate of the LNG energy station is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of LNG (liquefied natural gas), and in particular to a comprehensive process for improving the safety of LNG energy stations. Background Art

[0002] Currently, LNG (liquefied natural gas) energy stations have large storage tanks, with diameters exceeding 90 meters, making LNG stratification difficult to manage. When high volumes are flowing outside the receiving station, the operation or startup of multiple LNG high-pressure pumps can cause pressure fluctuations at the end of the low-pressure LNG main at the pump inlet, leading to pressure drops and, in severe cases, impacting pump startup and operation. When using an intermediate medium vaporizer for high-pressure LNG vaporization, consideration is given to the propane discharge process. LNG energy stations utilize three methods for treating intermediate propane: low-emission, flaring, and direct recovery. In new projects, these three methods fail to meet standards and specifications for on-site discharge, increase investment for flaring, and impact the BOG treatment system, creating operational inconveniences and, in severe cases, causing BOG (boil-off gas) flaring and energy waste. Due to geographical constraints and site conditions, the use of water-bath vaporizers for high-pressure LNG vaporization is prone to icing of equipment piping, compromising safe operation. Due to dwindling site resources, LNG energy station construction requires larger and larger sites, hindering future project development.

[0003] In view of this, the present invention is proposed. Summary of the Invention

[0004] The purpose of the present invention is to provide a comprehensive process for improving the safety of LNG energy stations, which solves the problems of poor safety, poor stability and low space utilization efficiency in the LNG energy station process, and achieves the technical effect of comprehensively improving the stability, safety and equipment utilization of LNG energy stations.

[0005] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are adopted:

[0006] A comprehensive process for improving the safety of LNG energy stations, including an LNG tank rollover prevention process, a pressure stabilization process, a propane release pretreatment and recovery process, a tank separation process, and a plate-type indirect heat exchange process;

[0007] The LNG storage tank anti-rollover process includes the following steps:

[0008] By stirring the LNG in the LNG storage tank, the temperature and density differences between adjacent layers are reduced, thereby preventing rolling;

[0009] The voltage stabilization process comprises the following steps:

[0010] Use pressure stabilizing facilities to stabilize the pressure at the end of the low-pressure LNG main pipe at the inlet of the LNG high-pressure pump to ensure the stability of the inlet pressure of the LNG high-pressure pump, thereby avoiding pump cavitation;

[0011] The propane release pretreatment recovery process comprises the following steps:

[0012] Pre-cool the released propane to liquefy the gaseous propane into liquid propane, reducing the amount of gaseous propane entering the BOG system of the storage tank, thereby avoiding affecting the BOG system;

[0013] The tank separation process comprises the following steps:

[0014] By installing an isolation sealing plate in the LNG storage tank, the tank is divided into at least two parts and the medium is filled separately, thereby improving equipment utilization;

[0015] The plate-type indirect heat exchange process comprises the following steps:

[0016] The heat between high-pressure LNG and circulating water is transferred through the intermediate medium enclosed in the heat exchange plate, thereby improving the heat exchange efficiency, preventing the circulating water from freezing, and reducing the space occupied by the equipment.

[0017] Furthermore, the stirring device used in the LNG storage tank anti-rollover process includes a jet stirrer.

[0018] Furthermore, the jet agitator is arranged at the bottom of the LNG storage tank.

[0019] Furthermore, the pressure stabilizing facility is arranged at the end of the low-pressure LNG main pipe at the inlet of the LNG high-pressure pump.

[0020] Furthermore, the pressure at the end of the low-pressure LNG main pipe at the inlet of the LNG high-pressure pump is stabilized between 0.6MpaG and 0.9MpaG.

[0021] Furthermore, the pre-cooling treatment includes pre-cooling the released propane using low-pressure super-cooled LNG.

[0022] Furthermore, in the pre-cooling process, the gaseous propane is liquefied into liquid propane through a low-temperature gas-liquid mixer.

[0023] Furthermore, the filling medium used in the tank separation process includes at least one of propane, ethane and LNG.

[0024] Furthermore, the intermediate medium used in the plate-type indirect heat exchange process includes at least one of methane, ethane, propane and a mixture (methane, ethylene, isopentane, propane).

[0025] Furthermore, the devices used in the integrated process include a BOG compressor, a liquefied gas transfer pump, an LNG low-pressure pump, an LNG high-pressure pump, a plate indirect heat exchanger, a liquefied gas storage tank, an LNG storage tank, a recondenser, a pressure stabilizing facility, a gas-liquid separation tank, an anti-rollover facility, a light hydrocarbon separation facility, a low-temperature gas-liquid blender, and a propane-LNG heat exchanger.

[0026] Compared with the prior art, the present invention has at least the following beneficial effects:

[0027] The comprehensive process for improving the safety of LNG energy stations provided by the present invention includes an LNG tank anti-rollover process, a pressure stabilization process, a propane discharge pretreatment recovery process, a tank separation process and a plate indirect heat exchange process, which solves the problems of poor safety, poor stability and low space utilization efficiency existing in the LNG energy station process, and achieves the technical effect of comprehensively improving the stability, safety and equipment utilization rate of the LNG energy station; specifically, the LNG tank anti-rollover process accelerates the blending of LNG at different depths by stirring the LNG in the LNG tank, effectively solves the problem of LNG stratification, reduces the temperature difference and density difference between adjacent layers, and thus prevents the occurrence of rolling; the pressure stabilization process uses a pressure stabilization facility to stabilize the pressure at the end of the low-pressure LNG main pipe at the inlet of the LNG high-pressure pump, ensures the stability of the LNG high-pressure pump inlet pressure away from the recondenser, enhances the operating stability of the LNG high-pressure pump, and effectively solves the problem The problem of pressure fluctuation at the high-pressure pump inlet away from the recondenser is solved, thereby avoiding pump cavitation; the propane discharge pretreatment recovery process pre-cools the discharged propane to liquefy the gaseous propane into liquid propane, thereby reducing the gaseous propane entering the BOG system of the storage tank and effectively reducing the impact of the propane recovery process on the BOG system; the tank separation process divides the tank into two parts by installing an isolation plate structure inside the tank. The tank is divided into at least two parts and filled with media with similar physical properties respectively, thereby effectively utilizing the tank space, increasing equipment utilization, reducing project site space, and solving the problem of limited project site; the plate indirect heat exchange process uses an indirect shell and tube heat exchanger, that is, filling an appropriate amount of intermediate medium in the sealed shell plate. The intermediate medium performs heat transfer, effectively isolating the direct heat exchange between high-pressure LNG and circulating water, preventing circulating water from freezing, solving the problem of heat exchanger freezing, and reducing equipment space. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are 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.

[0029] Figure 1 A schematic diagram of equipment connections, streams, and isolation valves in a comprehensive process for improving the safety of an LNG energy station, provided in accordance with one embodiment of the present invention;

[0030] Figure 2 A schematic structural diagram of a plate-type indirect heat exchanger provided in one embodiment of the present invention.

[0031] Icons: C-01-BOG compressor; P-01-liquefied gas transfer pump; P-02-LNG low-pressure pump; P-03-LNG high-pressure pump; E-01-plate indirect heat exchanger; T-01A-liquefied gas storage tank; T-01B-LNG storage tank; T-02-recondenser; T-03-pressure stabilizing facility; T-04-gas-liquid separation tank; X-01-first anti-rollover facility; X-02-second anti-rollover facility; X-03-light hydrocarbon separation facility; X-04-low-temperature gas-liquid blender; X-05-propane-LNG heat exchanger; 01-first low-pressure cryogenic LNG; 02-second low-pressure cryogenic LNG; 03-third low-pressure cryogenic LNG; 04-fourth low-pressure cryogenic LNG; 05-fifth low-pressure cryogenic LNG; 06-first low-pressure low-temperature LNG; 07-second low-pressure low-temperature LNG; 08-first high-pressure low-temperature LNG; 09-second high-pressure low-temperature LNG; 10-third low-pressure low-temperature LNG; 11-sixth low-pressure cryogenic LNG; 12-third high-pressure cryogenic LNG; 13-fourth high-pressure cryogenic LNG; 14-fifth high-pressure cryogenic LNG; 15-first high-pressure NG; 16-first low-pressure cryogenic liquefied gas; 17-seventh low-pressure cryogenic LNG; 18-eighth low-pressure cryogenic LNG; 19-ninth low-pressure cryogenic LNG; 20-second low-pressure cryogenic liquefied gas; 21-first low-pressure cryogenic NG; 22-low-pressure cryogenic LNG / NG; 23-second low-pressure cryogenic NG; 24-second high-pressure NG; 25- Circulating water supply; 26-Circulating water return; 27-Third low-pressure low-temperature liquefied gas; 28-Fourth low-pressure low-temperature liquefied gas; 29-Fifth low-pressure low-temperature liquefied gas; 30-Tenth low-pressure cryogenic LNG; 31-Low-pressure low-temperature LNG / liquefied gas; 32-Third low-pressure low-temperature NG; 33-Low-pressure propane gas; 34-High-pressure low-temperature LNG; 35-Third high-pressure NG; V-01-Liquid gas delivery pump P-01 outlet isolation valve; V-02-Liquid gas delivery pump P-01 return pipeline control valve; V-03-T-01B unloading inlet pipeline isolation valve; V-04-T-01B upper feed inlet pipeline control valve; V05-T-01B lower feed inlet pipeline control valve; V-06-T-01A lower feed inlet pipeline Control valves; V-07-T-01A upper feed inlet pipeline control valve; V-08-LNG low-pressure pump P-02 return pipeline control valve; V-09-LNG low-pressure pump P-02 outlet pipeline isolation valve; V-10-T-02 inlet LNG pipeline control valve; V-11-T-02 outlet LNG pipeline isolation valve; V-12-X-03 high-pressure LNG inlet pipeline isolation valve; V-13-P-03A inlet LNG pipeline isolation valve; V-14-T-03 low-pressure LNG inlet pipeline isolation valve; V-15-T-03 low-pressure LNG / NG outlet pipeline isolation valve; V-16-C-01 low-pressure NG inlet pipeline isolation valve; V-17-X-03 light hydrocarbon separation facility outlet liquefied gas pipeline isolation valve;V-18-X-03 Light Hydrocarbon Separation Facility Outlet High-Pressure NG Pipeline Isolation Valve; V-19-T-04 Outlet Low-Pressure LNG Pipeline Isolation Valve; V-20-T-04 Outlet Low-Pressure BOG Pipeline Isolation Valve; V-21-Low-Pressure Subcooled LNG Pipeline Control Valve; V-22-Propane-LNG Heat Exchanger X-05 Inlet High-Pressure LNG Pipeline Isolation Valve; V-23-Intermediate Medium Water Bath Heat Exchanger E-01 Inlet High-Pressure LNG Pipeline Isolation Valve; V-24-Propane-LNG Heat Exchanger X-05 Outlet High-Pressure NG Pipeline Isolation Valve; V-25-Intermediate Medium Water Bath Heat Exchanger E-01 Outlet Circulating Water Pipeline Isolation Valve; V-26-Intermediate Medium Water Bath Heat exchanger E-01 outlet high-pressure NG pipeline isolation valve; V-27 - intermediate medium water bath heat exchanger E-01 inlet circulating water pipeline isolation valve; V-28 - high-pressure LNG pipeline isolation valve; V-29 - P-03B inlet LNG pipeline isolation valve; V-30 - P-03C inlet LNG pipeline isolation valve; V-31 - P-03D inlet LNG pipeline isolation valve; V-32 - P-03A outlet LNG pipeline isolation valve; V-33 - P-03B outlet LNG pipeline isolation valve; V-34 - P-03C outlet LNG pipeline isolation valve; V-35 - P-03D outlet LNG pipeline isolation valve; V-36 - nitrogen pipeline isolation valve. DETAILED DESCRIPTION

[0032] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0033] The present invention provides a comprehensive process for improving the safety of LNG energy stations, including an LNG tank anti-rollover process, a pressure stabilization process, a propane release pretreatment recovery process, a tank separation process, and a plate-type indirect heat exchange process;

[0034] The LNG tank rollover prevention process includes the following steps:

[0035] By stirring the LNG in the LNG storage tank, the temperature and density differences between adjacent layers are reduced, thereby preventing rolling;

[0036] The voltage stabilization process includes the following steps:

[0037] Use pressure stabilizing facilities to stabilize the pressure at the end of the low-pressure LNG main pipe at the inlet of the LNG high-pressure pump to ensure the stability of the inlet pressure of the LNG high-pressure pump, thereby avoiding pump cavitation;

[0038] The propane release pretreatment recovery process includes the following steps:

[0039] Pre-cool the released propane to liquefy the gaseous propane into liquid propane, thereby reducing the amount of gaseous propane entering the storage tank BOG system and avoiding affecting the BOG system;

[0040] The tank separation process includes the following steps:

[0041] By installing an isolation sealing plate in the LNG storage tank, the tank is divided into at least two parts and the medium is filled separately, thereby improving equipment utilization;

[0042] The plate indirect heat exchange process includes the following steps:

[0043] The heat between high-pressure LNG and circulating water is transferred through the intermediate medium enclosed in the heat exchange plate, thereby improving the heat exchange efficiency, preventing the circulating water from freezing, and reducing the space occupied by the equipment.

[0044] In summary, the present invention solves the problems of poor safety, poor stability and low space utilization efficiency in the LNG energy station process, and achieves the technical effect of comprehensively improving the stability, safety and equipment utilization of the LNG energy station. It is suitable for LNG storage, pressurization and gasification, and also effectively utilizes the low-pressure LNG cooling capacity to pretreat gaseous propane, thereby achieving the purpose of safe and stable process operation.

[0045] In a preferred embodiment, the stirring device used in the LNG storage tank anti-rollover process includes but is not limited to a jet stirrer, and the jet stirrer can be arranged at the bottom of the LNG storage tank.

[0046] The jet agitator is rationally arranged at the bottom of the LNG storage tank. The low-pressure LNG from the LNG low-pressure pump is stirred with the LNG in the tank through the jet agitator, thereby increasing the stirring intensity of the LNG and achieving LNG blending. This can solve the problem of LNG stratification and reduce the temperature and density differences between adjacent layers, thereby effectively enhancing the anti-rollover capability of the tank and improving the safety of LNG storage in the tank.

[0047] In a preferred embodiment, the pressure stabilizing device can be arranged at the end of the low-pressure LNG main pipe at the inlet of the LNG high-pressure pump.

[0048] A pressure stabilizing facility is arranged at the end of the low-pressure LNG main pipe at the inlet of the LNG high-pressure pump. The pressure stabilizing facility ensures that the LNG pressure at the end of the low-pressure LNG main pipe at the inlet of the LNG high-pressure pump is stable, effectively solving the problem of LNG pressure fluctuation at the end of the low-pressure LNG main pipe at the inlet of the LNG high-pressure pump when multiple LNG high-pressure pumps are running or started at the same time.

[0049] In a preferred embodiment, the pressure at the end of the low-pressure LNG main pipe at the inlet of the LNG high-pressure pump can be stabilized between 0.6MpaG and 0.9MpaG, for example, it can be 0.6MpaG, 0.65MpaG, 0.7MpaG, 0.75MpaG, 0.8MpaG, 0.85MpaG, 0.9MpaG, but not limited to this.

[0050] In a preferred embodiment, the pre-cooling treatment includes but is not limited to pre-cooling the released propane using low-pressure super-cooled LNG.

[0051] Using low-pressure supercooled LNG to pre-cool the released propane, liquefying the gaseous propane into liquid propane, can reduce the amount of gaseous propane entering the storage tank BOG system, help reduce the impact of propane release on the BOG treatment system, and enhance the stability and safety of the BOG treatment system.

[0052] In the present invention, the gaseous propane is liquefied into liquid propane by a low-temperature gas-liquid blender during the pre-cooling process.

[0053] In a preferred embodiment, the filling medium used in the tank separation process includes but is not limited to at least one of propane, ethane and LNG.

[0054] Installing an isolation sealing plate in the LNG storage tank divides the tank into two or more parts, which are filled with appropriate media respectively (the media filled in a dual-purpose tank have similar physical properties, which is beneficial to the safety of the storage process). This can improve equipment utilization, effectively utilize the tank space, reduce the project site space size, and solve the problem of limited project site.

[0055] In a preferred embodiment, the intermediate medium used in the plate indirect heat exchange process includes but is not limited to at least one of methane, ethane, propane and a mixture (methane, ethylene, isopentane, propane).

[0056] The plate-type indirect heat exchange process is adopted, and an appropriate amount of intermediate medium is enclosed in the heat exchange plate. The intermediate medium is used to transfer heat. The heat transferred between the high-pressure LNG and the circulating water is transferred through the intermediate medium. This can not only improve the heat exchange efficiency, but also solve the freezing problem during the heat exchange between the circulating water and LNG, while also reducing the space occupied by the equipment; the temperature difference between the cold and hot substances is reduced from 150℃ to 110℃. Reducing the temperature difference between the cold and hot substances can improve the safety of the equipment body material.

[0057] It should be noted that the devices used in the comprehensive process of the present invention include but are not limited to BOG compressors, liquefied gas delivery pumps, LNG low-pressure pumps, LNG high-pressure pumps, plate indirect heat exchangers, liquefied gas storage tanks, LNG storage tanks, recondensers, pressure stabilizing facilities, gas-liquid separation tanks, anti-rollover facilities, light hydrocarbon separation facilities, low-temperature gas-liquid blenders, and propane-LNG heat exchange devices.

[0058] The present invention is further described below by way of examples. Unless otherwise specified, the materials in the examples were prepared according to existing methods or directly purchased from the market.

[0059] Example 1

[0060] A comprehensive process for improving the safety of LNG energy stations, including an LNG tank rollover prevention process, a pressure stabilization process, a propane release pretreatment and recovery process, a tank separation process, and a plate-type indirect heat exchange process;

[0061] LNG tank anti-rollover process: A jet agitator is installed at the bottom of the LNG tank. Low-pressure LNG from the LNG low-pressure pump is used to stir the LNG in the tank through the jet agitator, thereby enhancing the LNG stirring force, solving the problem of LNG stratification, achieving LNG blending, and reducing the temperature and density differences between adjacent layers, thereby preventing rollover.

[0062] Pressure stabilization process: A pressure stabilization facility is installed at the end of the low-pressure LNG main pipe at the inlet of the LNG high-pressure pump. The pressure stabilization facility ensures the stability of the LNG pressure at the end of the low-pressure LNG main pipe at the inlet of the LNG high-pressure pump, and ensures the stability of the LNG pressure at the inlet of the LNG high-pressure pump far away from the recondenser. This can solve the problem of LNG pressure fluctuation at the end of the low-pressure LNG main pipe at the inlet of the LNG high-pressure pump when multiple LNG high-pressure pumps are running or started at the same time, thereby enhancing the operating stability of the LNG high-pressure pump;

[0063] Propane release pretreatment and recovery process: Low-pressure subcooled LNG is used to pre-cool the released propane, and a low-temperature gas-liquid blender is used to liquefy the gaseous propane into liquid propane. This reduces the amount of gaseous propane entering the BOG system, thereby reducing the impact of propane release on the BOG treatment system and enhancing the stability and safety of the BOG treatment system.

[0064] Tank separation technology: Installing isolation sealing plates inside the LNG tank to divide the tank into two or more parts, each of which is filled with appropriate media. This can effectively improve equipment utilization and help reduce the space size of the project site;

[0065] Plate-type indirect heat exchange process: An appropriate amount of intermediate medium is enclosed in the heat exchange plate, and the heat transferred between the high-pressure LNG and the circulating water is transferred through the intermediate medium. This can not only improve the heat exchange efficiency, but also solve the freezing problem during the heat exchange between the circulating water and LNG, while also reducing the space occupied by the equipment.

[0066] The specific process steps of this embodiment are shown in Figure 1 :

[0067] Open valves V-02, V-06, V-08, V-09, V-10, V-11, V-12, V-13, V-14, V-15, V-16, V-17, V-18, V-20, V-21, V-22, V-23, V-24, V-25, V-26, V-27, V-29, V-31, V-32, V-33, V-34, V-35, V-36, close valves V-01, V-03, V-04, V-05, V-07, V-19, V-28, V-30;

[0068] Low-pressure subcooled LNG from T-01B enters pipeline 03 and is divided into three pipelines: 04, 05 and 11. In the first pipeline 04, low-pressure subcooled LNG enters T-02 and mixes with low-pressure BOG from pipeline 23 to generate low-pressure, low-temperature LNG, which then passes through pipeline 06 to pipeline 07 and finally enters LNG high-pressure pumps P-03A~D; in the second pipeline 05, when T-02 is isolated or the downstream demand for LNG is large, V-30 is opened and this pipeline is put into operation; in the third pipeline 11, low-pressure subcooled LNG enters T-03 at the end of the LNG high-pressure pump inlet main pipe after being controlled by control valve V-14, which is used to stabilize the pressure at the end of the LNG high-pressure pump inlet main pipe to ensure the stability of the operation of the LNG high-pressure pump away from T-02 when multiple LNG high-pressure pumps are running simultaneously. The operating pressure of T-03 is stably controlled at 0.6~0.9MpaG, and the liquid level in T-03 is controlled by valve V-15;

[0069] After being pressurized by the LNG high-pressure pump, the LNG is divided into four pipelines: 08, 13, 14, and 34. In the first pipeline 08, the high-pressure LNG enters X-03 for process operation. The generated liquefied gas (ethane, propane) and high-pressure NG are transported to the downstream through pipeline 15; in the second pipeline 13, the high-pressure LNG enters X-05 for gasification operation. The generated high-pressure NG is transported to the downstream through pipeline 35. The propane gas phase released under the special working conditions of X-05 is mixed with the low-pressure supercooled LNG in X-04 to generate liquid propane and a small amount of low-pressure and low-temperature NG, and then enters T-04 for separation. The low-pressure and low-temperature NG enters T-01B. The propane-rich LNG enters T-01B after being compressed by nitrogen; in the third pipeline 14, the high-pressure LNG enters E-01 (E-01 represents a plate indirect heat exchanger, its structure is shown in FIG. Figure 2 ), the high-pressure LNG first exchanges heat with the gaseous intermediate medium in the heat exchange jacket, the high-pressure LNG generates high-pressure NG, the gaseous intermediate medium generates liquid intermediate medium, the liquid intermediate medium exchanges heat with the circulating water, the liquid intermediate medium generates gaseous intermediate medium, and the circulating water after heat exchange is transported to the downstream for treatment. The intermediate medium gas-liquid circulation operation is carried out to transfer cold energy, thereby ensuring the requirements of high-pressure LNG gasification operation and meeting the requirements of isolated heat exchange between high-pressure LNG and circulating water; the fourth pipeline 34 transports the high-pressure LNG to other devices for operation;

[0070] The low-pressure, low-temperature liquefied gas from X-03 enters T-01A. T-01A and T-01B share a storage tank (T-01). T-01 is divided into two parts, T-01A and T-01B, by installing a partition. These two parts are filled with substances with similar operating temperatures and pressures. This configuration fully utilizes the refrigeration capacity of LNG and the storage tank space.

[0071] When LNG in tank T-01B is stratified (the temperature between adjacent depths is greater than ℃, the density is greater than kg / m 3 ), close V-09, open V-08, start the LNG low-pressure pump P-02, and the pressurized low-pressure LNG passes through pipelines 01 and 02 and enters X-01 for injection, stirring the LNG, mixing LNG at different depths, speeding up the processing of LNG stratification, and avoiding rolling.

[0072] Comparative Example 1

[0073] The difference between this comparative example and Example 1 is that the LNG in the LNG storage tank is not stirred;

[0074] The rest are the same as in Example 1.

[0075] Compared with Example 1, the drawback of this comparative example is that it is less effective in solving the problem of LNG stratification, cannot effectively achieve LNG blending in a timely manner, and is prone to tumbling.

[0076] Comparative Example 2

[0077] The difference between this comparative example and Example 1 is that no pressure stabilizing facility is used to stabilize the pressure at the end of the low-pressure LNG main pipe at the inlet of the LNG high-pressure pump;

[0078] The rest are the same as in Example 1.

[0079] Compared with Example 1, the drawback of this comparative example is that the stability of the inlet pressure of the LNG high-pressure pump cannot be guaranteed, the liquid level is seriously reduced, and pump cavitation is prone to occur.

[0080] Comparative Example 3

[0081] The difference between this comparative example and Example 1 is that the released propane is not pre-cooled (i.e., the gaseous propane is not liquefied into liquid propane);

[0082] The rest are the same as in Example 1.

[0083] Compared with Example 1, the drawback of this comparative example is that propane leaks into the storage tank BOG system, which has an adverse effect on the BOG treatment system.

[0084] Comparative Example 4

[0085] The difference between this comparative example and Example 1 is that no isolation sealing plate is provided in the LNG storage tank;

[0086] The rest are the same as in Example 1.

[0087] Compared with Example 1, the drawback of this comparative example is that it cannot improve the equipment utilization rate and is not conducive to reducing the project site space size.

[0088] Comparative Example 5

[0089] The difference between this comparative example and Example 1 is that an appropriate amount of intermediate medium is not enclosed in the heat exchange plate (i.e., the heat transferred between the high-pressure LNG and the circulating water is not transferred through the intermediate medium);

[0090] The rest are the same as in Example 1.

[0091] Compared with Example 1, the drawback of this comparative example is that freezing may occur during heat exchange between the circulating water and LNG.

[0092] In summary, the present invention solves the problems of poor safety, poor stability and low space utilization efficiency existing in the LNG energy station process, and achieves the technical effect of comprehensively improving the stability, safety and equipment utilization of the LNG energy station. It is suitable for LNG storage, pressurization and gasification, and also effectively utilizes the low-pressure LNG cooling capacity to pretreat gaseous propane, thereby achieving the purpose of safe and stable process operation.

[0093] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A comprehensive process for improving the safety of LNG energy stations, characterized in that: Including LNG tank anti-rollover process, pressure stabilization process, propane release pretreatment and recovery process, tank separation process and plate indirect heat exchange process; The LNG storage tank anti-rollover process includes the following steps: By stirring the LNG in the LNG storage tank, the temperature and density differences between adjacent layers are reduced, thereby preventing rolling; The voltage stabilization process comprises the following steps: Use pressure stabilizing facilities to stabilize the pressure at the end of the low-pressure LNG main pipe at the inlet of the LNG high-pressure pump to ensure the stability of the inlet pressure of the LNG high-pressure pump, thereby avoiding pump cavitation; The propane release pretreatment recovery process comprises the following steps: Pre-cool the released propane to liquefy the gaseous propane into liquid propane, reducing the amount of gaseous propane entering the BOG system of the storage tank, thereby avoiding affecting the BOG system; The tank separation process comprises the following steps: By installing an isolation sealing plate in the LNG storage tank, the tank is divided into at least two parts and the medium is filled separately, thereby improving equipment utilization; The plate-type indirect heat exchange process comprises the following steps: The heat between high-pressure LNG and circulating water is transferred through the intermediate medium enclosed in the heat exchange plate, thereby improving the heat exchange efficiency, preventing the circulating water from freezing, and reducing the space occupied by the equipment.

2. The integrated process according to claim 1, characterized in that The stirring device used in the LNG storage tank anti-rollover process includes a jet stirrer.

3. The integrated process according to claim 2, characterized in that The jet agitator is arranged at the bottom of the LNG storage tank.

4. The integrated process according to claim 1, characterized in that The pressure stabilizing facility is arranged at the end of the low-pressure LNG main pipe at the inlet of the LNG high-pressure pump.

5. The integrated process according to claim 4, characterized in that The pressure at the end of the low-pressure LNG main pipe at the inlet of the LNG high-pressure pump is stabilized between 0.6MpaG and 0.9MpaG.

6. The integrated process according to claim 1, characterized in that The pre-cooling treatment includes pre-cooling the released propane using low-pressure super-cooled LNG.

7. The integrated process according to claim 6, characterized in that In the pre-cooling process, gaseous propane is liquefied into liquid propane by a low-temperature gas-liquid blender.

8. The integrated process according to claim 1, characterized in that The filling medium used in the tank separation process includes at least one of propane, ethane and LNG.

9. The integrated process according to claim 1, characterized in that The intermediate medium used in the plate-type indirect heat exchange process includes at least one of methane, ethane and propane.

10. The integrated process according to any one of claims 1 to 9, characterized in that The devices used in the integrated process include a BOG compressor, a liquefied gas transfer pump, an LNG low-pressure pump, an LNG high-pressure pump, a plate-type indirect heat exchanger, a liquefied gas storage tank, an LNG storage tank, a recondenser, a pressure stabilizing facility, a gas-liquid separation tank, an anti-rollover facility, a light hydrocarbon separation facility, a low-temperature gas-liquid blender, and a propane-LNG heat exchange device.

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