Pre-cooling, filling and waste gas treatment system of LNG (Liquefied Natural Gas) fuel ship

Abstract

The invention relates to the technical field of storage and distribution of liquefied gas, and particularly discloses a pre-cooling, filling and waste gas treatment system of an LNG fuel ship, which comprises the following steps: S1, connecting a liquid nitrogen tank car with a gasification pry to pre-cool a fuel cabin of the LNG fuel ship; s11, low-temperature nitrogen / liquid nitrogen of the liquid nitrogen tank car is conveyed to the input pipeline through the gasification pry, and the low-temperature nitrogen / liquid nitrogen is conveyed to the fuel cabin through the input pipeline; s2, the LNG tank car is connected with a gasification pry to generate gasified natural gas to expel nitrogen in a fuel cabin of the LNG fuel ship, and LNG replacement of the fuel cabin is completed; s3, the LNG tank car achieves gas-phase pressurization through a gasification pry, LNG is conveyed to a fuel cabin through an input pipeline, and LNG filling of the fuel cabin is completed; and S4, the LNG tank car achieves gas-phase pressurization through the gasification pry and the filling pry, LNG enters an LNG immersed pump of the filling pry, the LNG is conveyed to the fuel cabin through the LNG immersed pump, and LNG filling of the fuel cabin is completed.

Description

Technical Field

[0001] The present invention relates to the technical field of storage and distribution of liquefied gases, and particularly to a pre-cooling, filling and waste gas treatment system for LNG fuel ships. Background Art

[0002] LNG, namely liquefied natural gas, generally has a storage temperature of about -160°C. Due to its low temperature and the characteristic of being easily volatilized into natural gas, ships using it as power are somewhat dangerous during the filling and use processes; LNG fuel ships generally need to complete liquid nitrogen pre-cooling and the first LNG filling operation at the shipyard, and the fuel tank needs to be pre-cooled before the first LNG filling to ensure that the temperature of the fuel tank is suitable for storing liquefied natural gas and to avoid safety problems and equipment damage caused by excessive temperature difference. In the prior art, the pre-cooling, filling, waste gas treatment and other operations for LNG fuel ships are all independent systems, and there is no complete set of treatment system to complete the pre-cooling, filling and waste gas treatment and other operations for LNG fuel ships. Therefore, there is an urgent need for a system integrating nitrogen pre-cooling, LNG filling and waste gas treatment operations to pre-cool and conduct the first filling operation on LNG fuel ships at the shipyard. Summary of the Invention

[0003] In view of this, the present invention provides a pre-cooling, filling and waste gas treatment system for LNG fuel ships to solve the technical problems in the above background art.

[0004] To achieve one or part or all of the above purposes or other purposes, the present invention provides: a pre-cooling, filling and waste gas treatment system for LNG fuel ships, comprising:

[0005] Step S1: Pre-cool the fuel tank of the LNG fuel ship by connecting a gasification skid with a liquid nitrogen tank truck;

[0006] The specific steps of step S1 are as follows:

[0007] Step S11: The low-temperature nitrogen / liquid nitrogen of the liquid nitrogen tank truck is transported to the input pipeline through the gasification skid, and the low-temperature nitrogen / liquid nitrogen is transported to the fuel tank through the input pipeline;

[0008] Step S12: The low-temperature nitrogen / liquid nitrogen exchanges heat with the fuel tank, and is sequentially transported to the heating skid and the pilot flare system through the discharge pipeline for waste gas treatment and discharge;

[0009] Step S2: Connect a gasification skid with an LNG tank truck to generate gasified natural gas to expel nitrogen in the fuel tank of the LNG fuel ship, and complete the LNG replacement of the fuel tank;

[0010] Step S3: The LNG tank truck realizes gas phase pressurization through the gasification skid, and the LNG is transported to the fuel tank through the input pipeline to complete the LNG filling of the fuel tank;

[0011] Step S4: The LNG tank truck realizes gas phase pressurization through the gasification skid and the filling skid, and the LNG enters the LNG submersible pump of the filling skid. The LNG is transported to the fuel tank through the LNG submersible pump, and the LNG filling of the fuel tank is completed.

[0012] Preferably, the step S11 comprises:

[0013] Step S110: The liquid nitrogen in the liquid nitrogen tank truck is gasified and heated by the air-temperature gasifier in the gasification skid to form low-temperature nitrogen;

[0014] Step S111: cryogenic nitrogen is delivered to the fuel tank through an input pipeline.

[0015] Preferably, the step S11 comprises:

[0016] Step S112: the liquid nitrogen tank truck is pressurized by its own supercharger, and a pressure difference is formed between the liquid nitrogen tank truck and the gasification skid;

[0017] Step S113: The ultra-low temperature nitrogen or a small amount of liquid nitrogen in the liquid nitrogen tank truck enters the input pipeline through the valve V104 (V104') of the gasification skid under the action of pressure difference and is transported to the fuel tank.

[0018] Preferably, the step S11 further includes:

[0019] Step S114: A large amount of liquid nitrogen in the liquid nitrogen tank truck enters the input pipeline through the valve V103 (V103') of the gasification skid under the action of pressure difference and is transported to the fuel tank.

[0020] Preferably, the step S3 comprises:

[0021] Step S31: The LNG in the LNG tank truck flows through the tank truck liquid phase valve and then enters the air-temperature vaporizer of the vaporization skid for vaporization and pressurization. The LNG tank truck gas phase;

[0022] Step S32: Under the action of pressure difference, the LNG in the LNG tank truck enters the input pipeline through the valve V103 (V103') of the gasification skid and is transported to the fuel tank.

[0023] Preferably, the step S3 further comprises:

[0024] Step S33: Under the action of pressure difference, the LNG in the LNG tanker enters the input pipeline through the valve V103 (V103') of the gasification skid, and the LNG enters the LNG submersible pump through the input pipeline and valve V205, and the LNG is transported to the fuel tank through the LNG submersible pump.

[0025] Preferably, the step S4 comprises:

[0026] Step S41: The LNG in the LNG tank truck parked at the gasification skid enters the LNG submersible pump through the loop as in Step 31 and Step S32.

[0027] Step S42: The LNG in the LNG tank truck parked at the filling skid flows by gravity through the liquid-phase valve of the tank truck and then enters the booster of the filling skid for gasification and pressurization. The gas phase of the LNG tank truck; the LNG in the LNG tank truck enters the LNG submersible pump through the valve V203 (V203’) of the filling skid under the action of the pressure difference.

[0028] Step S43: After being mechanically pressurized by the LNG submersible pump, the LNG is transported through the input pipeline to the bottom of the fuel tank through the valve V207.

[0029] Preferably, in the said Step S4:

[0030] The gas return port DN40 of the LNG submersible pump is connected to the LNG tank truck through the valve V206 to form a first gas return line;

[0031] The gas return port DN40 of the LNG submersible pump is connected to the discharge pipeline through the valve V206’ to form a second gas return line.

[0032] Preferably, an electric heater is provided in the heating skid for heating the waste gas returned from the fuel tank.

[0033] Preferably, the pilot flare system includes a flare combustion tower, a multi-stage burner, a pilot light, a flare ignition device, and electrical control equipment.

[0034] Implementing the embodiments of the present invention will have the following beneficial effects:

[0035] After adopting the above scheme, the present invention uses the gasification skid to realize the precooling and replacement operations of the fuel tank in the LNG fuel ship. When performing short-distance and low-pressure LNG filling operations, the LNG tank truck can be parked at the gasification skid, and the gasification skid can be used to realize the LNG filling operation of the fuel tank. When performing long-distance and high-pressure LNG filling operations, the gasification skid is used as the transfer liquid path of the LNG submersible pump of the filling skid to provide LNG for the LNG submersible pump, improving the liquid inlet efficiency of the LNG submersible pump, and then completing the LNG filling operation of the fuel tank; when performing precooling and filling operations, the fuel tank and the heating skid are connected through the discharge pipeline to realize the heating treatment of the waste gas, and then the pilot flare system at the rear end is used to realize the safe discharge of the waste gas. Generally speaking, this system integrates precooling, filling, and waste gas treatment. Multiple operations such as precooling, LNG replacement, LNG filling, and auxiliary LNG filling are realized through the gasification skid with multiple uses, meeting the requirements of the shipyard for the first filling operation of the LNG fuel ship. The entire filling process is more efficient, reliable, and safe. Description of the Drawings

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0037] Among them:

[0038] Figure 1 It is the process schematic diagram in the embodiment;

[0039] Figure 2 It is the overall circuit schematic diagram in the embodiment;

[0040] Figure 3 It is the circuit schematic diagram of the gasification skid in the embodiment;

[0041] Figure 4 It is the circuit schematic diagram of the filling skid in the embodiment;

[0042] Figure 5 It is the circuit schematic diagram of the heating skid and the pilot flare system in the embodiment;

[0043] Figure 6 It is the schematic diagram of the first pre-cooling line in the embodiment;

[0044] Figure 7 It is the schematic diagram of the second pre-cooling line in the embodiment;

[0045] Figure 8 It is the schematic diagram of the third pre-cooling line in the embodiment;

[0046] Figure 9 It is the schematic diagram of the first filling line in the embodiment;

[0047] Figure 10 It is the schematic diagram of the second filling line in the embodiment;

[0048] Figure 11 It is the schematic diagram of the third filling line in the embodiment. Detailed implementation manners

[0049] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this invention belongs; the terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit the present invention; the terms "including" and "having" and any variations thereof in the specification and claims of the present invention and the above drawings are intended to cover non-exclusive inclusion. The terms "first", "second", etc. in the specification and claims of the present invention or the above drawings are used to distinguish different objects and not to describe a specific order.

[0050] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in connection with the embodiments can be included in at least one embodiment of the present invention. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0051] To enable those skilled in the technical field to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0052] As shown in the Figures 1-11 accompanying drawings, the embodiments of the present invention provide a pre-cooling, filling, and exhaust gas treatment system for an LNG fuel ship, including:

[0053] Step S1: Pre-cool the fuel tank of the LNG fuel ship by connecting a liquid nitrogen tank truck to a vaporization skid.

[0054] Specifically, Step S1 is as follows:

[0055] Step S11: The low-temperature nitrogen / liquid nitrogen of the liquid nitrogen tank truck is transported to the input pipeline through the vaporization skid, and the low-temperature nitrogen / liquid nitrogen is transported to the fuel tank through the input pipeline.

[0056] Step S12: The low-temperature nitrogen / liquid nitrogen exchanges heat with the fuel tank and is sequentially transported to the heating skid and the pilot flare system through the discharge pipeline for exhaust gas treatment and discharge.

[0057] Step S2: Connect the LNG tank truck to the vaporization skid to generate vaporized natural gas to expel the nitrogen in the fuel tank of the LNG fuel ship, and complete the LNG replacement in the fuel tank.

[0058] Step S3: The LNG tank truck realizes gas phase pressurization through the vaporization skid, and the LNG is transported to the fuel tank through the input pipeline to complete the LNG filling of the fuel tank.

[0059] Step S4: The LNG truck realizes gas-phase pressurization through the vaporizer and filling skid. The LNG enters the LNG submersible pump of the filling skid and is transported to the fuel tank through the LNG submersible pump, completing the LNG filling of the fuel tank.

[0060] In step S1, in order to ensure that the temperature of the fuel tank is suitable for storing liquefied natural gas and avoid safety problems and equipment damage caused by excessive temperature difference, precooling is required before the first filling. The temperature reduction rate has different requirements according to the model of the LNG fuel ship and can be adjusted according to the needs during actual operation. There are two 1000 Nm 3 air-cooled vaporizers in the vaporizer skid of this embodiment, which are used as vaporizers and superchargers during precooling to provide nitrogen and liquid nitrogen at different temperatures. When the LNG truck docks at the vaporizer skid, the air-cooled vaporizer is used as a supercharger for the pressurization of the LNG truck. An emergency cut-off valve is also set on the liquid main pipe in the vaporizer skid, which can be controlled remotely or by an emergency button on-site; a pull-off valve is also set at the connection port with the truck. When an emergency occurs, the truck can drive away directly without disassembling the hose; a flow meter and a pneumatic valve are also set at the gas outlet end of the vaporizer skid, which can monitor the output flow in real time and automatically switch the start valve to avoid over-limit flow output to the rear end; at the same time, safety accessories such as safety valves, pressure and temperature monitoring instruments, and combustible gas detection alarms are equipped according to the pressure pipeline design principles; in order to meet the usage requirements, explosion-proof LED lights, mesh isolation doors and other facilities are also set in the vaporizer skid.

[0061] Therefore, step S1 provides multiple precooling methods, and any one of the following precooling methods or any combination of multiple precooling methods can be selected according to actual needs. In this embodiment, the circuits of the following multiple precooling methods will be described one by one with reference to the accompanying drawings:

[0062] Step S110: The liquid nitrogen in the liquid nitrogen truck is vaporized and heated through the air-cooled vaporizer in the vaporizer skid to form low-temperature nitrogen.

[0063] Step S111: The low-temperature nitrogen is transported to the fuel tank through the input pipeline.

[0064] Specifically, the vaporizer skid can vaporize and heat the liquid nitrogen in the liquid nitrogen truck through the vaporizer to form nitrogen with a temperature lower than the ambient temperature, and then transport it to the fuel tank of the LNG ship through the input pipeline for precooling and replacement, as Figure 6For the pre-cooling line 1 shown, the liquid nitrogen tank truck first boosts its own pressure through the supercharger it comes with, creating a pressure difference between the liquid nitrogen tank truck and the vaporizer skid; under the action of the pressure difference, liquid nitrogen flows from valve V101 (V101') - valve V107 (V107') - air-cooled vaporizer, is vaporized and heated up by the air-cooled vaporizer - V105 (V105') - input pipeline - fuel tank. The liquid nitrogen undergoes internal heat exchange - discharge pipeline - heating skid, is heated - long-burning torch system to ensure safe discharge. Among them, the input pipeline includes at least the intake valve V210, and the discharge pipeline includes at least the outlet valve V211; in addition, the temperature of the gas after vaporization can be further controlled by controlling the number of heat exchangers involved, the opening degree of the valve at the inlet end of the vaporizer, and the pressure difference between the tank truck and the system, with reference to the real-time temperature monitoring at the rear end of the vaporizer. For example: the outlet temperature of the vaporizer can be reduced by only starting one vaporizer, increasing the opening degree of the inlet end valve, and increasing the pressure difference; at the same time, a flow meter is installed at the outlet end of the vaporizer skid to monitor the amount of output flow in real time, and the pneumatic valve will also automatically open and close according to the size of the real-time flow to ensure that there will be no over-limit situation; in addition, a turbine flow meter and a temperature transmitter are installed at the outlet of the heating skid to monitor the amount of gas output to the torch system in real time. When it exceeds or approaches the limit, an alarm will be issued. When it exceeds the limit by a certain degree, the gas supply of the entire system can also be cut off. It should be noted that specific values can be set on-site for this part.

[0065] The vaporizer skid can directly provide ultra-low temperature gaseous nitrogen or a small amount of liquid nitrogen through the preset valves inside the skid to further improve the pre-cooling effect, as follows:

[0066] Step S112: The liquid nitrogen tank truck boosts pressure through the supercharger it comes with, creating a pressure difference between the liquid nitrogen tank truck and the vaporizer skid;

[0067] Step S113: The ultra-low temperature nitrogen or a small amount of liquid nitrogen in the liquid nitrogen tank truck enters the input pipeline through valve V104 (V104') of the vaporizer skid under the action of the pressure difference and is transported to the bottom of the fuel tank.

[0068] Such as Figure 7The pre-cooling line two shown below. Ultra-low temperature nitrogen or a small amount of liquid nitrogen enters the fuel tank through the valve V104 (V104') - the input pipeline, undergoes internal heat exchange - the discharge pipeline - the heating skid, is heated - and then enters the pilot flare system to ensure safe discharge. The control of the amount of ultra-low temperature nitrogen and a small amount of liquid nitrogen can be achieved by switching the gas-liquid valve of the liquid nitrogen tank truck and adjusting the opening degree of the valve V104 (V104'). For example: opening the liquid phase valve of the liquid nitrogen tank truck and then adjusting the opening degree of the valve V104 (V104') can adjust the amount of liquid nitrogen (a small amount) entering the system; at the same time, a flow meter is installed at the gas outlet end of the vaporization skid to monitor the output flow rate (mass data) in real time, and the pneumatic valve will also automatically open and close according to the size of the real-time flow rate to ensure that no over-limit situation occurs; in addition, a turbine flow meter and a temperature transmitter are installed at the outlet of the heating skid to monitor the gas volume output to the flare system in real time. When it exceeds or approaches the limit, an alarm will be triggered. When it exceeds the limit by a certain degree, the gas supply of the entire system can also be cut off (the specific value of this part can be set on-site).

[0069] When a large amount of liquid nitrogen is needed in the final stage, the vaporization skid can directly provide liquid nitrogen equivalent to the extracted liquid volume of the liquid nitrogen tank truck through the preset valves inside the skid to further improve the pre-cooling effect, as follows:

[0070] Step S114: A large amount of liquid nitrogen in the liquid nitrogen tank truck enters the input pipeline through the valve V103 (V103') of the vaporization skid under the action of the pressure difference and is transported to the fuel tank.

[0071] As Figure 8 The pre-cooling line three shown below. The liquid nitrogen tank truck first increases its own pressure through the boosting effect of the built-in booster, creating a pressure difference between the liquid nitrogen tank truck and the rear pipeline - under the action of the pressure difference, liquid nitrogen enters the fuel tank through the valve V103 (V103') - the input pipeline, undergoes internal heat exchange - the discharge pipeline - the heating skid, is heated - and then enters the pilot flare system to ensure safe discharge. The control of the liquid nitrogen volume can be achieved by adjusting the opening degree of the valve V103 (V103'); at the same time, a turbine flow meter and a temperature transmitter are installed at the outlet of the heating skid to monitor the gas volume output to the flare system in real time. When it exceeds or approaches the limit, an alarm will be triggered. When it exceeds the limit by a certain degree, the gas supply of the entire system can also be cut off (the specific value of this part can be set on-site).

[0072] So far, step S1 is completed, and the fuel tank has completed the pre-cooling operation. After the pre-cooling is completed, the vaporization skid can also be used for the LNG replacement operation of the fuel tank of the LNG fuel ship. For example, in step S2: Connect the LNG tank truck to the vaporization skid to generate vaporized natural gas to expel the nitrogen in the fuel tank of the LNG fuel ship and complete the LNG replacement of the fuel tank, specifically as Figure 6The pre-cooling line 1 shown. At this time, the liquid nitrogen tank truck is replaced with an LNG tank truck. The LNG in the LNG tank truck is converted into vaporized natural gas through an air-cooled vaporizer, and enters the fuel tank through the input pipeline. Due to density reasons, the vaporized natural gas will squeeze the nitrogen remaining in the fuel tank upward out of the fuel tank. Finally, the mixed gas of the vaporized natural gas and nitrogen is output to the heating skid through the discharge pipeline, and after heating, it is safely discharged to the pilot flare system.

[0073] After the pre-cooling of the fuel tank and the replacement of LNG are completed, the vaporizer in this embodiment can also be used as a filling skid, that is, the LNG in the fuel tank of the LNG fuel ship can be filled by docking the LNG tank truck at the vaporizer. The specific steps are as follows:

[0074] Step S31: The LNG in the LNG tank truck flows by gravity through the liquid-phase valve of the tank truck and enters the air-cooled vaporizer of the vaporizer for vaporization and pressurization. The gas phase of the LNG tank truck;

[0075] Step S32: The LNG in the LNG tank truck enters the input pipeline under the action of the pressure difference through the valve V103 (V103’) of the vaporizer and is transported to the fuel tank.

[0076] As Figure 9 Shown in filling line 1, first, the LNG in the LNG tank truck flows by gravity through the tank truck boost liquid-phase valve - valve V101 (V101’) - air-cooled vaporizer, vaporizes and pressurizes - valve V102 (V102’) - the gas phase of the LNG tank truck to complete pressurization. Then, the LNG in the LNG tank truck enters the fuel tank through the valve V103 (V103’) - input pipeline under the action of the pressure difference. It should be noted that the transmission distance, height, and pressure provided by filling line 1 are relatively small compared to pump delivery, and it is suitable for filling operations with short distances, low heights, and low pressures. At the same time, through the turbine flowmeter and temperature transmitter set at the outlet of the heating skid, the gas volume output to the flare system is monitored in real time. When it exceeds or approaches the limit, an alarm will be triggered. When it exceeds the limit by a certain degree, the gas supply of the entire system can also be cut off (the specific value of this part can be set on-site).

[0077] For cases where the requirements for transmission distance, height, and pressure are relatively high and the vaporizer cannot meet these requirements, the vaporizer can transfer the LNG in two LNG tank trucks to the inlet pipeline of the filling skid (pump skid) to improve the inlet capacity of the LNG submersible pump. Specifically:

[0078] Step S33: The LNG in the LNG tank truck enters the input pipeline under the action of the pressure difference through the valve V103 (V103’) of the vaporizer. The LNG enters the LNG submersible pump through the input pipeline and valve V205, and the LNG is transported to the bottom of the fuel tank through the LNG submersible pump.

[0079] As Figure 10For the shown refueling line 2, first, the LNG in the LNG tank truck flows by gravity through the tank truck booster liquid-phase valve - valve V101 (V101') - to the air-cooled vaporizer, where it is vaporized and pressurized - valve V102 (V102') - to the LNG tank truck gas phase, completing the pressurization. Then, the LNG in the LNG tank truck enters the LNG submersible pump through valve V103 (V103') - the input pipeline - valve V205 under the action of pressure difference. The LNG submersible pump is used to refuel the fuel tank. By combining the vaporization skid and the refueling skid, the LNG refueling of the fuel tank can be completed under the conditions of higher requirements for transportation distance, height, and pressure. The pipeline of the vaporization skid is reasonably utilized to realize the repeated use of the pipeline and improve the work efficiency.

[0080] In addition to the pre-cooling operation, replacement operation, refueling operation, and auxiliary refueling operation of the above vaporization skid, this embodiment also provides a refueling skid, also known as a pump skid, which is mainly used to "pump" the LNG in the LNG tank truck to the fuel tank of the LNG fuel ship. A low-temperature LNG submersible pump is arranged in the refueling skid for pumping LNG, with a maximum head of 130 meters; a 300-cubic-meter supercharger is used to pressurize the LNG tank truck to improve the liquid inlet efficiency of the pump skid; a 200-cubic-meter EAG heater is used for reheating the discharged NG; at the same time, an emergency cut-off valve is arranged on the liquid main pipe in the skid, which can be controlled remotely or by an emergency button on-site; a pull-off valve is also arranged at the connection port with the tank truck, so that the tank truck can drive away directly without disassembling the hose in case of an emergency; a flow meter and a pneumatic valve are arranged at the output end of the refueling skid, which can monitor the output flow in real time and automatically adjust the amount of output flow to avoid over-limit flow input into the backend system. At the same time, safety accessories such as safety valves, pressure and temperature monitoring instruments, and combustible gas detection alarms are equipped according to the design principles of pressure pipelines; in order to meet the usage requirements, facilities such as explosion-proof LED lights and mesh isolation doors are also arranged.

[0081] The following specific line is adopted for LNG refueling of the LNG fuel ship.

[0082] Step S41: The LNG in the LNG tank truck parked at the vaporization skid enters the LNG submersible pump through the loop of step 210 and step S212.

[0083] Step S42: The LNG in the LNG tank truck parked at the refueling skid flows by gravity through the tank truck liquid-phase valve and then enters the supercharger of the refueling skid for vaporization and pressurization, to the LNG tank truck gas phase; the LNG in the LNG tank truck enters the LNG submersible pump through valve V203 (V203') of the refueling skid under the action of pressure difference.

[0084] Step S43: After being mechanically pressurized by the LNG submersible pump, the LNG is transported through valve V207 to the bottom of the fuel tank through the input pipeline.

[0085] As Figure 11The shown refueling line three first has the LNG in the LNG tank of the gasification skid stop and the LNG flows by gravity through the tank truck boost liquid phase valve - valve V101 (V101') - air-cooled vaporizer, vaporizes and boosts - valve V102 (V102') - LNG tank truck gas phase, completing the boosting. Then the LNG in the LNG tank truck enters the LNG submersible pump through valve V103 (V103') - input pipeline - valve V205 due to the pressure difference;

[0086] Meanwhile, the LNG in the LNG tank truck parked at the refueling skid flows by gravity through the tank truck boost liquid phase valve - valve V201 (V201') - supercharger, vaporizes and boosts - valve V202 (V202') - LNG tank truck gas phase, completing the boosting. Then the LNG in the LNG tank truck enters the LNG submersible pump through valve V203 (V203') due to the pressure difference;

[0087] Then, the LNG submersible pump mechanically boosts - valve V207 - input pipeline - fuel tank.

[0088] During the operation of the LNG submersible pump, gas return and continuous gas return are required to ensure normal operation. At this time, there are two gas return lines:

[0089] The gas return port DN40 of the LNG submersible pump is connected to the LNG tank truck through valve V206 to form the first gas return line;

[0090] The gas return port DN40 of the LNG submersible pump is connected to the discharge pipeline through valve V206' to form the second gas return line;

[0091] Among them, the first gas return line is only applicable to the situation where the tank truck pressure is not high and there is a lot of liquid. In the case of high tank truck pressure and low liquid level, there will be a situation of poor gas return. At this time, the second gas return line can be selected.

[0092] At the same time, the liquid outlet end of the pump skid is equipped with a flowmeter, which can monitor the output flow in real time. The pneumatic valve will also automatically open and close according to the size of the real-time flow to ensure that there will be no over-limit situation; in addition, a turbine flowmeter and a temperature transmitter are set at the outlet of the heating skid, which can monitor the gas volume output to the flare system in real time. When it exceeds or approaches the limit, an alarm will be given. When it exceeds the limit by a certain degree, the gas supply of the entire system can also be cut off (the specific value of this part can be set on-site).

[0093] In this embodiment, an electric heater is provided in the heating skid to heat the waste gas returned from the fuel tank. The electric heater is specifically a 2000 Nm 3A water-bath type electric heater with a heating capacity of / h heats the waste gas through the electric heater to ensure the temperature for the subsequent arranged emission of the pilot flare system; the designed power of the heater is 90 kw, and the lowest designed metal temperature is -196°C; according to the requirements of different projects, the reheating capacity of the electric heater can be set to be more than twice that of a conventional reheater; the electric heater adopts an explosion-proof design and has two gears, automatic and manual; in the automatic gear, temperature control operation can be realized, that is, it starts and stops automatically when the water temperature is between 50 - 60°C, starts heating when the water temperature is lower than 50°C, and stops heating when it is higher than 60°C; in the manual gear, it is always in the heating state and requires personnel to take care. At the same time, a combustible gas detection alarm is equipped according to the design principle of pressure pipelines; in addition, a turbine flowmeter and a temperature transmitter are set at the outlet of the heating skid, which can monitor the gas volume output to the flare system in real time, and will alarm when it exceeds or approaches the limit, and can also cut off the gas supply of the entire system when it exceeds the limit by a certain degree (the specific value can be set on-site for this part); in order to ensure the usage requirements, facilities such as explosion-proof LED lights and mesh isolation doors are also set up.

[0094] To ensure the safe emission of waste gas, the present invention also provides an independent pilot flare system. The pilot flare system includes a flare combustion tower, a multi-stage burner, a pilot light, a flare ignition device, and electrical control equipment. The flare combustion tower in this embodiment is of a mobile modular type, with a skid-mounted base, which is convenient for installation, disassembly, and transportation. The system is composed of a ground flare with a height of about 10 m and a diameter of about 2.4 m in a tower structure; the flare combustion is completed inside a cylindrical ground steel flare cylinder with a diameter of about 2.4 m and a height of about 10 m. The combustion process is completely enclosed, with no visible firelight from the outside, no light pollution, low heat radiation, and the flame height not exceeding the cylinder body when operating at full load. The outer shell of the cylindrical ground combustion furnace is made of carbon steel, lined with refractory ceramic fiber, ceramic fiber compensation blanket, and ceramic fiber flat blanket, and the total thickness of the 3-cm backing is not less than 170 mm. It is not affected by rain or rapid changes in the internal temperature of the cylinder body, and at the same time has good sound absorption and noise reduction characteristics, and ensures that the outer surface temperature of the cylinder body does not exceed 60 °C when the flare operates at full load for a long time; the multi-stage burner adopts a plum blossom-shaped porous structure, which can divide a large stream of flare gas into many small streams to facilitate its mixing with air, increase the contact area with air, and achieve smokeless combustion. The mixing of air and flare gas is mainly completed by relying on the pressure of the flare gas itself and a specially designed burner. The plum blossom-shaped porous burners are geometrically evenly arranged inside the cylindrical ground combustion furnace to make full use of air. The burner is made of heat-resistant stainless steel to ensure its long service life; there are 2 ignition pilot lights inside the flare cylinder. The pilot lights remain constantly lit under normal conditions so that any flare gas emission can be promptly ignited at any time to ensure the absolute safety of the system. The pilot lights are equipped with automatic ignition devices, that is, when the pilot lights are extinguished due to external factors, they can automatically re-ignite the pilot lights to ensure the reliability of the ground flare ignition. The components of the pilot lights should all be detachable for easy maintenance and replacement of vulnerable parts, and the fuel gas consumption of each pilot light should not exceed 5 Nm 3 / h, and ensure that the pilot lights have stable safety and reliability and good energy-saving effects; the flare should have a reliable and safe ignition device and strong self-cleaning ability, not affected by gas pollution, resistant to oil, water, coking, and high temperature, with the characteristics of safety, reliability, no pollution, and long life; it also has a flame detection device with a simple structure, convenient operation, and reliable performance, which can continuously detect various combustion environments for a long time, and is equipped with an independent local control cabinet that can complete the local manual ignition function; the electrical part includes a local explosion-proof control cabinet and an explosion-proof box. The explosion-proof box is used for power distribution on the flare equipment, and the local explosion-proof control cabinet is used for all control operations of the flare system, with functions such as on-site instrument display, buttons, indicator lights, alarms, and remote transmission;

[0095] To improve safety, anti-static grounding is also carried out at the combustion tower body, pipeline system and other places. The working grounding, protective grounding, lightning protection grounding and anti-static grounding devices in the unit are all connected together to form a common grounding network, and the grounding resistance value is designed to be ≤ 1 ohm. Electrical equipment, cable brackets, etc. are all provided with lightning protection and anti-static grounding. The process pipeline of fuel gas must be provided with anti-static grounding. For the explosion-proof ignition control panel, the static grounding wire uses yellow-green insulated wire, and the wire diameter meets the specification requirements. The shielding layer of the analog signal shielded cable must be grounded at one end.

[0096] In summary, the present invention uses a gasification skid to achieve the precooling operation and replacement operation of the fuel tank in the LNG fuel ship. When performing short-distance and low-pressure LNG filling operations, the LNG tanker can be parked beside the gasification skid, and the gasification skid is used to achieve the LNG filling operation of the fuel tank. When performing long-distance and high-pressure LNG filling operations, the gasification skid is used as the transfer liquid path of the LNG cryogenic pump of the filling skid to provide LNG for the LNG cryogenic pump, improving the liquid inlet efficiency of the LNG cryogenic pump, and then completing the LNG filling operation of the fuel tank; when performing precooling and filling operations, the fuel tank and the heating skid are connected through the discharge pipeline to achieve the heating treatment of the waste gas, and then the safe discharge of the waste gas is realized through the long-burning torch system at the rear end. Generally speaking, this system integrates precooling, filling and waste gas treatment. Through the multi-purpose gasification skid, multiple operations such as precooling, LNG replacement, LNG filling and auxiliary LNG filling are realized, meeting the requirements of the shipyard for the first filling operation of the LNG fuel ship. The entire filling process is more efficient, reliable and safe.

[0097] Obviously, the embodiments described above are only a part of the embodiments of the present invention, rather than all of the embodiments. The preferred embodiments of the present invention are given in the drawings, but do not limit the patent scope of the present invention. The present invention can be implemented in many different forms. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosed content of the present invention more thorough and comprehensive. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing specific embodiments, or perform equivalent replacements for some of the technical features. Any equivalent structure directly or indirectly using the content of the specification and drawings of the present invention in other related technical fields shall be within the scope of the patent protection of the present invention by the same token.

Claims

1. A precooling, filling and exhaust gas treatment system for an LNG fuel ship, characterized in that: include: Step S1: precooling the fuel tank of the LNG fuel ship by connecting the gasification skid with a liquid nitrogen tank truck; The step S1 is specifically as follows: Step S11: The cryogenic nitrogen / liquid nitrogen in the liquid nitrogen tank truck is transported to the input pipeline through the gasification skid, and the cryogenic nitrogen / liquid nitrogen is transported to the fuel tank through the input pipeline; Step S12: The cryogenic nitrogen / liquid nitrogen exchanges heat with the fuel tank and is sequentially transported to the heating skid and the ever-lit flare system through the discharge pipeline for waste gas treatment and discharge; Step S2: The LNG tanker is connected to the gasification skid to generate gasified natural gas to drive out the nitrogen in the fuel tank of the LNG fuel ship, thereby completing the LNG replacement of the fuel tank; Step S3: The LNG tank truck realizes gas phase pressurization through the gasification skid, and the LNG is transported to the fuel tank through the input pipeline, completing the LNG filling of the fuel tank; Step S4: The LNG tank truck realizes gas phase pressurization through the gasification skid and the filling skid, and the LNG enters the LNG submersible pump of the filling skid. The LNG is transported to the fuel tank through the LNG submersible pump, and the LNG filling of the fuel tank is completed.

2. The precooling, filling and exhaust gas treatment system for an LNG fuel ship according to claim 1, characterized in that: The step S11 comprises: Step S110: The liquid nitrogen in the liquid nitrogen tank truck is gasified and heated by the air-temperature gasifier in the gasification skid to form low-temperature nitrogen; Step S111: cryogenic nitrogen is delivered to the fuel tank through an input pipeline.

3. The precooling, filling and exhaust gas treatment system for an LNG fuel ship according to claim 2, characterized in that: The step S11 comprises: Step S112: the liquid nitrogen tank truck is pressurized by its own supercharger, and a pressure difference is formed between the liquid nitrogen tank truck and the gasification skid; Step S113: The ultra-low temperature nitrogen or a small amount of liquid nitrogen in the liquid nitrogen tank truck enters the input pipeline through the valve V104 (V104') of the gasification skid under the action of pressure difference and is transported to the fuel tank.

4. The precooling, filling and exhaust gas treatment system for an LNG fuel ship according to claim 3, characterized in that: The step S11 further includes: Step S114: A large amount of liquid nitrogen in the liquid nitrogen tank truck enters the input pipeline through the valve V103 (V103') of the gasification skid under the action of pressure difference and is transported to the fuel tank.

5. The precooling, filling and exhaust gas treatment system for an LNG fuel ship according to claim 1, characterized in that: The step S3 comprises: Step S31: The LNG in the LNG tank truck flows through the tank truck liquid phase valve and then enters the air-temperature vaporizer of the vaporization skid for vaporization and pressurization. The LNG tank truck gas phase; Step S32: Under the action of pressure difference, the LNG in the LNG tank truck enters the input pipeline through the valve V103 (V103') of the gasification skid and is transported to the fuel tank.

6. The precooling, filling and exhaust gas treatment system for an LNG fuel ship according to claim 5, characterized in that: The step S3 also includes: Step S33: Under the action of pressure difference, the LNG in the LNG tanker enters the input pipeline through valve V103 (V103') of the gasification skid, and the LNG enters the LNG submersible pump through the input pipeline and valve V205. The LNG is transported to the bottom of the fuel tank by the LNG submersible pump.

7. The precooling, filling and exhaust gas treatment system for an LNG fuel ship according to claim 6, characterized in that: The step S4 comprises: Step S41: the LNG in the LNG tank truck docked at the gasification skid enters the LNG submersible pump through the loop of steps 31 and S32; Step S42: The LNG in the LNG tank truck docked with the filling skid flows by gravity through the tank truck liquid phase valve and enters the supercharger of the filling skid for gasification and pressurization. The LNG in the LNG tank truck enters the LNG submersible pump through the valve V203 (V203') of the filling skid under the action of the pressure difference. Step S43: The LNG submersible pump mechanically pressurizes the LNG and then delivers it to the bottom of the fuel tank through the input pipeline after passing through valve V207.

8. The precooling, filling and exhaust gas treatment system for an LNG fuel ship according to claim 7, characterized in that: In step S4: The return air port DN40 of the LNG submersible pump is connected to the LNG tank truck through valve V206 to form return air line 1; The return air port DN40 of the LNG submersible pump is connected to the discharge pipeline through valve V206' to form the return air line 2.

9. The precooling, filling and exhaust gas treatment system for an LNG fuel ship according to claim 1, characterized in that: An electric heater is provided inside the heating skid for heating the exhaust gas returned from the fuel tank.

10. The precooling, filling and exhaust gas treatment system for an LNG fuel ship according to claim 1, characterized in that: The ever-burning torch system comprises a torch combustion tower, a multi-stage burner, a ever-burning lamp, a torch ignition device and an electrical control device.

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