WO2019063025A1 - 浮式液化天然气存储和气化装置、控制系统及控制方法 - Google Patents

浮式液化天然气存储和气化装置、控制系统及控制方法 Download PDF

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WO2019063025A1
WO2019063025A1 PCT/CN2018/114233 CN2018114233W WO2019063025A1 WO 2019063025 A1 WO2019063025 A1 WO 2019063025A1 CN 2018114233 W CN2018114233 W CN 2018114233W WO 2019063025 A1 WO2019063025 A1 WO 2019063025A1
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Prior art keywords
pressure zone
pressure
tank
storage tank
medium
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PCT/CN2018/114233
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English (en)
French (fr)
Inventor
庞维龙
侯晓羽
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泰恩博能燃气设备（天津）股份有限公司
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Publication of WO2019063025A1 publication Critical patent/WO2019063025A1/zh

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C7/00—Methods or apparatus for discharging liquefied, solidified, or compressed gases from pressure vessels, not covered by another subclass
    • F17C7/02—Discharging liquefied gases
    • F17C7/04—Discharging liquefied gases with change of state, e.g. vaporisation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C13/00—Details of vessels or of the filling or discharging of vessels
    • F17C13/002—Details of vessels or of the filling or discharging of vessels for vessels under pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C13/00—Details of vessels or of the filling or discharging of vessels
    • F17C13/02—Special adaptations of indicating, measuring, or monitoring equipment
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C13/00—Details of vessels or of the filling or discharging of vessels
    • F17C13/02—Special adaptations of indicating, measuring, or monitoring equipment
    • F17C13/025—Special adaptations of indicating, measuring, or monitoring equipment having the pressure as the parameter
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C13/00—Details of vessels or of the filling or discharging of vessels
    • F17C13/04—Arrangement or mounting of valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2205/00—Vessel construction, in particular mounting arrangements, attachments or identifications means
    • F17C2205/03—Fluid connections, filters, valves, closure means or other attachments
    • F17C2205/0302—Fittings, valves, filters, or components in connection with the gas storage device
    • F17C2205/0323—Valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2205/00—Vessel construction, in particular mounting arrangements, attachments or identifications means
    • F17C2205/03—Fluid connections, filters, valves, closure means or other attachments
    • F17C2205/0302—Fittings, valves, filters, or components in connection with the gas storage device
    • F17C2205/0323—Valves
    • F17C2205/0332—Safety valves or pressure relief valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2221/00—Handled fluid, in particular type of fluid
    • F17C2221/03—Mixtures
    • F17C2221/032—Hydrocarbons
    • F17C2221/033—Methane, e.g. natural gas, CNG, LNG, GNL, GNC, PLNG
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2223/00—Handled fluid before transfer, i.e. state of fluid when stored in the vessel or before transfer from the vessel
    • F17C2223/01—Handled fluid before transfer, i.e. state of fluid when stored in the vessel or before transfer from the vessel characterised by the phase
    • F17C2223/0146—Two-phase
    • F17C2223/0153—Liquefied gas, e.g. LPG, GPL
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2225/00—Handled fluid after transfer, i.e. state of fluid after transfer from the vessel
    • F17C2225/01—Handled fluid after transfer, i.e. state of fluid after transfer from the vessel characterised by the phase
    • F17C2225/0107—Single phase
    • F17C2225/0123—Single phase gaseous, e.g. CNG, GNC
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2227/00—Transfer of fluids, i.e. method or means for transferring the fluid; Heat exchange with the fluid
    • F17C2227/01—Propulsion of the fluid
    • F17C2227/0121—Propulsion of the fluid by gravity
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2227/00—Transfer of fluids, i.e. method or means for transferring the fluid; Heat exchange with the fluid
    • F17C2227/01—Propulsion of the fluid
    • F17C2227/0128—Propulsion of the fluid with pumps or compressors
    • F17C2227/0135—Pumps
    • F17C2227/0142—Pumps with specified pump type, e.g. piston or impulsive type
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2227/00—Transfer of fluids, i.e. method or means for transferring the fluid; Heat exchange with the fluid
    • F17C2227/04—Methods for emptying or filling
    • F17C2227/043—Methods for emptying or filling by pressure cascade
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2250/00—Accessories; Control means; Indicating, measuring or monitoring of parameters
    • F17C2250/03—Control means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2250/00—Accessories; Control means; Indicating, measuring or monitoring of parameters
    • F17C2250/04—Indicating or measuring of parameters as input values
    • F17C2250/0404—Parameters indicated or measured
    • F17C2250/043—Pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2270/00—Applications
    • F17C2270/01—Applications for fluid transport or storage
    • F17C2270/0102—Applications for fluid transport or storage on or in the water
    • F17C2270/0105—Ships

Definitions

  • the invention belongs to the technical field of LNG storage, transportation and gasification, and particularly relates to a floating storage and gasification device for continuously supplying natural gas fuel to port natural gas users and power plants, including control system and control of the storage and gasification device. method.
  • LNG is an abbreviation for Liquefied Natural Gas, whose main component is methane. LNG is cooled to -162 ° C by atmospheric natural gas under normal pressure to make it condense into a liquid. Natural gas liquefaction can greatly save storage and transportation space, with high calorific value and high performance.
  • LNG is a clean and efficient energy source. LNG is the preferred fuel in many countries. The proportion of natural gas in the energy supply is increasing rapidly. LNG will become the next hot energy commodity in the global competition after oil.
  • the water transportation of LNG can greatly reduce the transportation cost.
  • the existing LNG transportation vessels have large tonnages and can only enter various ports, and cannot dock at close distances, and cannot directly match the users.
  • Existing LNG storage devices need to occupy a certain amount of land, and in practical applications, there are problems such as long construction period, poor mobility, and high land use cost.
  • the present invention aims to propose a floating liquefied natural gas storage and gasification device, a control system and a control method for solving the problem of occupied land, long construction period and movable when existing users and power plants use LNG. Problems such as poor performance and high energy costs.
  • a floating liquefied natural gas storage and gasification device comprising a hull, at least one intermediate pressure zone storage tank is arranged on the hull, and the medium pressure zone storage tank is sequentially connected with the low pressure zone buffer tank, the submerged liquid pump box and the LNG gasification device;
  • the outlet of the medium pressure zone storage tank is located at the top of the tank body, and the outlet port of the low pressure zone buffer tank is located at the bottom of the LNG.
  • One end of the liquid output pipeline extends from the outlet of the medium pressure zone storage tank to the bottom of the LNG, and the liquid output pipeline The other end is connected to the low pressure zone buffer tank;
  • the medium pressure zone storage tank and the low pressure zone buffer tank are provided with an air supply pipe, and the working air pressure in the tank body is controlled by the air supply pipe, and the lower limit of the working air pressure of the medium pressure zone storage tank is higher than the upper limit of the working pressure of the low pressure zone buffer tank, and the work is completed.
  • the pressure difference of the air pressure, the medium pressure zone storage tank provides continuous LNG to the low pressure zone buffer tank;
  • the bottom of the buffer tank in the low pressure zone is connected to the inlet of the submerged pump tank through the liquid output pipeline, and the cavity of the buffer tank of the low pressure zone is electrically connected to the cavity of the submerged pump tank through the vent line, and the vent line buffers the low pressure zone.
  • the working pressure of the tank is always the same as the working pressure of the submersible pump tank, and the LNG flowing into the buffer tank of the low pressure zone continuously flows into the submerged pump tank;
  • the submersible pump tank supplies continuous LNG to the LNG gasification unit through the submersible pump, and the LNG gasification unit supplies continuous high pressure gaseous natural gas to the gas utilization equipment.
  • the medium pressure zone storage tank is a vacuum double liquid storage tank or a single layer pressure storage liquid storage tank
  • the low pressure area buffer tank is a vacuum double buffer tank or a single layer pressure buffer tank.
  • the outer tank of the vacuum double-layer liquid storage tank is made of carbon steel, and the inner tank of the vacuum double-layer liquid storage tank is made of stainless steel; the tank of the single-layer pressurized storage tank is made of stainless steel, and the outer circumference is wound. Insulation material, the tank of the single-layer pressure buffer tank is made of stainless steel, and the outer layer is insulated with insulation material; the outer tank of the vacuum double-layer buffer tank is made of stainless steel, and the inner tank of the vacuum double-layer buffer tank is made of stainless steel.
  • the vacuum double-layer liquid storage tank, the vacuum double-layer buffer tank, the single-layer pressure storage liquid storage tank and the single-layer pressure buffer tank are all C-type storage tanks.
  • the hull is provided with at least two medium-pressure zone storage tanks, and the liquid inlet of the medium-pressure zone storage tank is located at the top of the tank body, and the medium-pressure zone storage tanks are connected in parallel with the total liquid inlet through the liquid input pipeline.
  • the total liquid inlet provides LNG to the medium pressure zone storage tank through the liquid input pipeline, and the medium pressure zone storage tanks are connected in parallel with the low pressure zone buffer tank through the liquid output pipeline.
  • liquid input pipeline is a steel pipe or a hose
  • liquid output pipeline is a steel pipe or a hose
  • an upper liquid shower head is arranged on the liquid inlet of the medium pressure zone storage tank.
  • a first on-off valve for controlling whether the medium-pressure zone storage tank supplies liquid to the low-pressure zone buffer tank is provided at the liquid outlet of each medium-pressure zone storage tank; the liquid inlet of each medium-pressure zone storage tank is provided There is a second on-off valve for controlling whether the total inlet port supplies liquid to the medium pressure zone storage tank; a medium pressure air supply valve is arranged on the air supply pipe of each medium pressure zone storage tank, and a low pressure is provided on the air supply pipe of the low pressure zone buffer tank Air supply valve.
  • a gas pressure detector is disposed in the medium pressure zone storage tank and the low pressure zone buffer tank.
  • a safety release valve is further disposed in the medium pressure zone storage tank and the low pressure zone buffer tank.
  • control system for a floating liquefied natural gas storage and gasification device comprising a switch control unit, a gas pressure detecting unit and a processing unit;
  • the switch control unit comprises a first on-off valve for controlling whether the medium-pressure zone storage tank supplies liquid to the low-pressure zone buffer tank, a second on-off valve that controls whether the total liquid inlet port supplies liquid to the medium-pressure zone storage tank, and controls each medium-pressure a medium pressure air supply valve for working air pressure in the storage tank of the zone, and a low pressure air supply valve for controlling the working air pressure in the buffer tank of the low pressure zone;
  • the air pressure detecting unit comprises a gas pressure detecting meter disposed in each medium pressure zone storage tank and a low pressure zone buffer tank, and the air pressure detecting meter detects the working air pressure values in the medium pressure zone storage tank and the low pressure zone buffer tank in real time;
  • the processing unit comprises a PLC controller for controlling the operation of each of the first on-off valve, the second on-off valve, the medium-pressure air supply valve and the low-pressure air supply valve;
  • the air pressure detecting unit sends the working air pressure value in each medium pressure zone storage tank and the working air pressure value in the low pressure area buffer tank to the processing unit;
  • the processing unit selects a medium pressure zone storage tank and a low pressure zone buffer tank by controlling the first switching valve, and the processing unit controls the working pressure P1 of the medium pressure zone storage tank through the medium pressure air supply valve of the selected medium pressure zone storage tank. It is always larger than the working pressure P2 of the low pressure zone storage tank.
  • the processing unit controls the working air pressure P1 in the medium pressure zone storage tank to be maintained within the working pressure range: Pa ⁇ P1 ⁇ Pb; Pa is the lower working pressure limit of the medium pressure zone storage tank, and when P1 is lower than Pa, The medium pressure air supply valve is opened, the air supply pipe is filled with gas into the medium pressure zone storage tank; Pb is the upper working pressure upper limit of the medium pressure zone storage tank, when the P1 is higher than the Pb, the medium pressure air supply valve is closed, and the air supply pipe stops the air supply. .
  • the working pressure P2 of the low pressure zone buffer tank is kept within the working pressure range: Pc ⁇ P2 ⁇ Pd; Pc is the lower working pressure limit of the buffer tank of the low pressure zone, and when the P2 is lower than Pc, the low pressure makeup valve is opened.
  • the gas supply pipe is filled with gas into the buffer tank of the low pressure zone; Pd is the upper limit of the working pressure of the buffer tank of the low pressure zone.
  • P2 is higher than Pd, the low pressure air supply valve is closed, and the air supply pipe stops the air supply.
  • medium pressure air supply valve and the low pressure air supply valve are pneumatic on-off valves.
  • first switching valve, the second switching valve, the medium pressure air supply valve and the low pressure air supply valve are normally closed switching valves.
  • the processing unit further includes a wireless communication module, the processing unit is connected to the remote server through the wireless communication module, and the remote server is connected to the intelligent terminal, and the intelligent terminal acquires data in the processing unit through the remote server and the wireless communication module, and the intelligent terminal passes the The remote server, the wireless communication module, and the processing unit control the switching action of the switch control unit.
  • the method for controlling a floating liquefied natural gas storage and gasification device comprises the following steps:
  • LNG carrier is connected with the total inlet of the hull, the high-pressure natural gas outlet of the hull is connected with the gas equipment, and the processing unit sequentially opens the second switching valve to input LNG into the storage tank of each medium-pressure zone, and the storage tank of the medium-pressure zone
  • the working pressure P1 ranges from: Pa-Pb
  • the working pressure P2 of the low-pressure zone buffer tank is: Pc-Pd, wherein Pb>Pa>Pd>Pc;
  • the processing unit selects a medium pressure zone storage tank as a working storage tank by controlling the operation of each first switching valve, and the LNG flows from the working storage tank into the low pressure zone buffer tank under the action of the working air pressure difference;
  • the working pressure of the buffer tank of the low pressure zone is always the same as the working pressure of the submerged pump tank through the vent line, and the LNG flowing into the buffer tank of the low pressure zone continuously flows into the submerged pump tank;
  • the submerged pump continuously transports the LNG in the submerged pump box to the LNG gasification device;
  • the LNG gasification device continuously supplies high-pressure gaseous natural gas to the gas-using equipment;
  • the low pressure air supply valve When the working pressure P2 of the buffer tank of the low pressure zone is lower than Pc, the low pressure air supply valve is opened, and the air supply pipe supplies air to the buffer tank of the low pressure zone. When the working air pressure P2 of the low pressure zone buffer tank is higher than Pd, the low pressure air supply valve is closed. The qi tube stops the qi.
  • the method further includes the step S7, the processing unit turns off the first on-off valve of the working storage tank, and the processing unit selects another medium-pressure zone storage tank as the new working storage tank by controlling the switching action of each of the first switching valves.
  • the processing unit selects the working storage tank by opening the first switching valve of the target medium pressure zone storage tank and closing the first switching valve of the remaining medium pressure zone storage tank.
  • the floating liquefied natural gas storage and gasification device Compared with the prior art, the floating liquefied natural gas storage and gasification device, the control system and the control method of the invention have the following advantages:
  • the floating liquefied natural gas storage and gasification device of the present invention wherein a plurality of medium-pressure zone storage tanks are arranged on the ship, and the medium-pressure zone storage tank is a vacuum double-layer liquid storage tank, and a reasonable load capacity is designed to enable the hull to be docked.
  • the draft On the shore with a small water depth, the draft is at least 3-4 meters deep, which is convenient for docking with users and power plants. It not only solves the problem that large transport ships can only dock in deep water areas such as ports, but also avoids natural gas storage and gas.
  • the device needs to occupy land;
  • the liquid outlet of the liquid storage tank is located at the upper part, and the liquid storage tank of the upper liquid outlet is continuously supplied to the submerged pump tank, and a vacuum double-layer buffer tank and a vacuum double-layer buffer tank are provided.
  • the body is small, so the cost control of the whole device is reasonable.
  • the vacuum double-layer buffer tank is used to realize continuous supply of liquid to the submerged pump box and the LNG gasification device, thereby providing continuous high-pressure gaseous natural gas to the user or the power plant;
  • the use of the upper liquid spray can reduce the production of BOG (Boil Off Gas) in the medium pressure zone and increase the storage time of LNG;
  • BOG Bit Off Gas
  • the external submersible pump has low cost of manufacturing, installation and maintenance, low power consumption and stable operation; C-type storage tank is easy to manufacture, durable and has good heat preservation.
  • the control system of the floating liquefied natural gas storage and gasification device can control the pressure of each medium-pressure zone storage tank and the low-pressure zone buffer tank and the flow of LNG through each of the on-off valve and the supplemental gas valve, and has control Convenient and can realize the advantages of remote control and automatic control.
  • FIG. 1 is a schematic structural view of a floating liquefied natural gas storage and gasification apparatus according to an embodiment of the present invention
  • FIG. 2 is a schematic diagram showing pressure division of a floating liquefied natural gas storage and gasification apparatus according to an embodiment of the present invention.
  • 10-medium pressure zone storage tank 11-liquid output pipeline; 121-first switching valve; 122-second switching valve; 13-upper liquid sprinkler head; 14-liquid input pipeline; 151-medium pressure air supply Valve; 152-low pressure air supply valve; 16-fill pipe; 17-total inlet; 18-low pressure zone buffer tank; 19-submersible pump; 20-submersible pump box; 21-LNG gasification unit; High pressure natural gas outlet; 23-hull; 24-vent line; 25-safe release valve.
  • connection is disassembled or connected integrally; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and may be internal communication between the two elements.
  • the specific meaning of the above terms in the creation of the present invention can be understood by one of ordinary skill in the art.
  • the existing LNG transport vessels have large tonnages and can only enter the port and cannot be docked on the shallow water coast. They cannot be directly connected with gas-using equipment, and need transfer equipment, which increases the cost of gas for natural gas;
  • Double-layer liquid storage tanks have specific requirements for the liquid discharge mode of the storage tank:
  • a lower liquid discharge mode can be adopted, which can realize continuous supply of the medium-pressure zone storage tank 10 to the submerged pump tank 20 by utilizing the gravity of the LNG.
  • LNG when the inner and outer layers of the vacuum double-layer liquid storage tank are made of stainless steel, the cost of the liquid storage tank is high, especially as the volume of the vacuum double-layer liquid storage tank increases, the cost will also increase exponentially.
  • the present invention provides a floating liquefied natural gas storage and gasification apparatus that does not occupy land.
  • the system includes a hull 23, and the hull 23
  • the minimum draft is between 3-4 meters, and the hull 23 can be conveniently docked on most of the coast. It not only solves the problem that large ships cannot directly connect with users, but also solves the problem that the natural gas relay equipment needs to occupy land. Greatly reduce the cost of gas for high-pressure natural gas;
  • the hull 23 is provided with at least one medium-pressure zone storage tank 10, which is a vacuum double-layer liquid storage tank, and the vacuum double-layer liquid storage tank is a general-purpose equipment for storing and transporting liquefied natural gas, and a large vacuum double-layer.
  • the liquid storage tank is extremely expensive to manufacture, and the present invention reduces the use cost of the storage tank by storing LNG separately by using a plurality of smaller vacuum double-layer liquid storage tanks, and the tank body 23 is usually provided with 4-8 vacuum double-layer liquid storage tanks. It is easy to know that the technical solution does not limit the number of vacuum double-layer liquid storage tanks.
  • a plurality of vacuum double-layer liquid storage tanks are arranged on the hull 23, and a reasonable load capacity is designed, so that the hull 23 carrying the vacuum double-layer liquid storage tank can be docked on the shore with a small water depth to facilitate docking with the power plant.
  • the core problem of how to extract LNG and continuously supply liquid to the LNG gasification device 21 to be solved by the technical solution can be disassembled into several consecutive small problems.
  • the control of the liquid level of the pump box 20 and the control of the working air pressure of the submerged pump unit 20 if the LNG speed entering the submersible pump box 20 is too fast, the liquid level of the submersible pump box 20 rises too fast, and the liquid pump box 20 is inside.
  • the cavity in the submerged pump tank 20 usually needs to be electrically connected to a liquid storage chamber for discharging the BOG.
  • the medium pressure zone storage tank 10 is matched with the submerged pump tank 20
  • the cavity of the submerged pump tank 20 cannot find a suitable liquid storage. The cavity fits, if the liquid storage chamber is separately configured, the cost is unnecessarily increased.
  • the submerged liquid pump 19 is usually used to extract the LNG.
  • the LNG itself has a light specific gravity and a low temperature
  • the submerged liquid pump 19 has a very high requirement.
  • the cost of the submersible pump 19 equipment is often as high as several million, which is very unfavorable for the gas cost control of natural gas.
  • the vacuum double-layer liquid storage tank used in the present scheme uses carbon steel for the outer layer and stainless steel for the inner layer.
  • the hull 23 is provided with at least one medium pressure zone storage tank 10, and the medium pressure zone storage tank 10 is sequentially connected with the low pressure zone buffer tank 18, the submerged liquid pump tank 20 and the LNG gasification device 21;
  • the outlet of the tank 10 is located at the top of the tank, the outlet of the buffer tank 18 of the low pressure zone is located at the bottom of the LNG, and the end of the liquid output line 11 extends from the outlet of the storage tank 10 of the intermediate pressure zone to the bottom of the LNG, the liquid output line The other end of 11 is connected to the low pressure zone buffer tank 18;
  • a low pressure zone buffer tank 18 is provided, and the low pressure zone buffer tank 18 is a vacuum double buffer tank, and the inner and outer double layers of the vacuum double buffer tank are made of stainless steel, in order to control the costly storage tank.
  • the vacuum double-layer buffer tank is small in volume, and the cost is relatively low.
  • the vacuum double-layer buffer tank Since all the vacuum double-layer liquid storage tanks are set to a certain working pressure, the vacuum double-layer buffer tank also has a certain working pressure range, and the working pressure of the vacuum double-layer liquid storage tank can always be higher than the vacuum double-layer buffer tank.
  • the LNG is delivered to the vacuum double buffer tank using a pressure differential. This pressure difference uses the pressure difference to extract the LNG from the vacuum double-layer liquid storage tank.
  • the submerged liquid pump 19 After the LNG is pumped from the medium pressure zone storage tank 10 into the low pressure zone buffer tank 18, if the submerged liquid pump 19 is disposed inside the low pressure zone buffer tank 18, the cost, maintenance, maintenance, etc. of the built-in submerged liquid pump 19 still exist.
  • the problem, in particular, the submersible pump 19 needs to stop when there is a problem replacement, resulting in the interruption of the continuous supply of LNG, so it is necessary to use a separate submerged pump box 20, that is, the medium pressure zone storage tank 10, the low pressure zone buffer tank 18 and the latent Continuous connection of the liquid pump box 20.
  • the external submersible pump 19 has low manufacturing, installation and maintenance costs, low power consumption, and stable operation.
  • the external submersible pump 19 still has a big problem, and it is difficult to operate normally in actual operation and achieve the purpose of continuously supplying liquid LNG.
  • the problems mainly include the control of the liquid level of the submerged pump tank 20 and the submerged pump box. 20 working pressure control, and 20BOG discharge of the submersible pump box, but the series is perfectly solved by setting the vacuum double buffer tank and turning on the vacuum double buffer tank and the cavity of the submersible pump box 20. problem.
  • the functions of the vacuum double-layer buffer tank include: 1. Forwarding the LNG with the vacuum double-layer liquid storage tank; 2. Cooperating with the submerged pump tank 20, the liquid outlet of the vacuum double-layer buffer tank is disposed at the bottom of the LNG.
  • the conventional continuous gravity LNG supply by gravity is restored, and since the vacuum double-layer buffer tank is electrically connected to the submerged pump tank 20 through the vent line 24, the vacuum double-layer buffer tank can simultaneously adjust the liquid level of the submerged pump tank 20 and working pressure.
  • the vacuum double buffer tank has a safety relief valve 25, the BOG in the submersible pump tank 20 can also be discharged.
  • the function of the venting line 24 includes: 1. Turning on the vacuum double-layer buffer tank and the submerged pump box 20, so that the vacuum double-layer buffer tank can realize the automatic flow of the LNG into the submerged pump box 20 by using the LNG self-weight; The high-level and low-level three-stage pressure is formed between the liquid storage tank, the vacuum double-layer buffer tank and the submerged pump tank 20.
  • This design method causes the working pressure range of the equipment in each pressure range to be too narrow, and the equipment needs frequent switching and design cost.
  • the solution uses the vent line 24 to conduct the vacuum double-layer buffer tank and the submerged pump box 20, so that the working pressures of the vacuum double-layer buffer tank and the submerged pump box 20 are always the same, and the three-stage pressure will be Simplified to the secondary pressure, and the air pressure control device in the submerged pump tank 20 is also omitted. Since the working pressures of the vacuum double buffer tank and the submerged pump tank 20 are always the same, the LNG flowing into the vacuum double buffer tank automatically flows to In the submersible pump box 20. 3.
  • the BOG in the submerged pump tank 20 can be led to the vacuum double buffer tank, and the BOG can be discharged by the safety release valve 25 of the vacuum double buffer tank.
  • a floating liquefied natural gas storage and gasification device including a hull 23, is provided with at least one vacuum double-layer liquid storage tank on the hull 23, and each vacuum double-layer liquid storage tank is connected with a vacuum double-layer buffer tank, and the vacuum double
  • the layer buffer tank is connected to the submerged pump tank 20, and the submerged pump tank 20 is connected to the LNG gasification unit 21; the liquid outlet of the vacuum double layer liquid storage tank is located at the top of the tank body, and the liquid outlet of the vacuum double layer buffer tank is located at the LNG At the bottom, one end of the liquid output line 11 extends from the outlet of the vacuum double-layer liquid storage tank to the bottom of the LNG, and the other end is connected to the vacuum double-layer buffer tank; the vacuum double-layer liquid storage tank and the vacuum double-layer buffer tank are provided with a supplement
  • the gas pipe 16 controls the working pressure of the vacuum double-layer liquid storage tank through the gas supply pipe 16 to be always larger than the vacuum double-layer buffer tank.
  • the vacuum double-layer liquid storage tank provides continuous to the vacuum double-layer buffer tank through the liquid output line 11 LNG; the vent line 24 conducts the vacuum double-layer buffer tank and the submerged pump box 20 so that the working pressures of the two are always the same, and the LNG flowing into the vacuum double-layer buffer tank continuously flows into the submerged pump tank 20; the submerged pump tank 20 passes The submersible pump 19 is provided to the LNG gasification device 21
  • the LNG gasification unit 21 supplies continuous high pressure gaseous natural gas to the gas plant.
  • each medium pressure zone storage tank 10 is in the range of the medium pressure zone, and the vacuum double buffer tank and the submerged fluid pump tank 20 are in the low pressure zone range.
  • the technical solution of this embodiment has the following advantages: a plurality of medium-pressure zone storage tanks 10 are arranged on the ship, and the medium-pressure zone storage tanks 10 are vacuum double-layer liquid storage tanks, and a reasonable load capacity is designed, so that the hull 23 can be stopped at a small water depth.
  • the draft has a minimum depth of 3-4 meters, which is convenient for docking with users and power plants. It not only solves the problem that large transport vessels can only dock in deep water areas such as ports, but also avoids the need for natural gas storage and gasification equipment.
  • the problem of land; the vacuum double-layer liquid storage tank uses the lower cost outer layer of carbon steel or other thermal insulation material, and the inner layer is stainless steel tank.
  • the cost of the carbon steel tank is much lower than that of the stainless steel tank. Body, so this solution avoids the use of large, expensive large-scale liquid storage tanks. Under the same LNG weight, the cost of the device is about 10% of the hull 23 of the stainless steel large-scale liquid storage tank.
  • the double-layer buffer tank realizes continuous supply of liquid to the submerged pump tank 20 and the LNG gasification unit 21, thereby providing continuous high-pressure gaseous natural gas to the user or the power plant.
  • the vacuum double-layer liquid storage tank and the vacuum double-layer buffer tank may also be arranged as a single-layer pressure-bearing liquid storage tank and a single-layer pressure-bearing buffer tank.
  • the tank body of the single-layer pressure-bearing liquid storage tank is made of stainless steel, and the periphery Wound insulation material, the tank of the single-layer pressure buffer tank is made of stainless steel, and the outer layer is wrapped with insulation material.
  • the vacuum double-layer liquid storage tank, the vacuum double-layer buffer tank, the single-layer pressure storage liquid tank and the single-layer pressure buffer tank are all C-type storage tanks.
  • the C-type storage tank is easy to manufacture, durable and has good heat preservation.
  • the hull 23 is provided with at least two medium pressure zone storage tanks 10, the liquid inlet of the medium pressure zone storage tank 10 is located at the top of the tank body, and the medium pressure zone storage tanks 10 pass through the liquid input pipeline 14 and the total liquid inlet port. 17 is connected in parallel, and the total liquid inlet 17 supplies LNG to the medium pressure zone storage tank 10 through the liquid input line 14, and the total liquid inlet port 17 can simultaneously supply LNG to the plurality of medium pressure zone storage tanks 10, or can be separately medium pressure.
  • the zone storage tank 10 provides LNG, and each of the intermediate pressure zone storage tanks 10 is connected in parallel with the low pressure zone buffer tank 18 through the liquid output line 11 each time, and each of the medium pressure zone storage tanks 10 is selected to supply LNG to the low pressure zone buffer tank 18.
  • the liquid input line 14 is a steel pipe or a hose
  • the liquid output line 11 is a steel pipe or a hose.
  • the liquid inlet port of the medium pressure zone storage tank 10 is provided with an upper liquid shower head 13.
  • the use of the upper liquid spray can reduce the generation of 10BOG in the medium pressure zone storage tank and increase the storage time of the LNG.
  • each medium pressure zone storage tank 10 is provided with a first on-off valve 121 for controlling whether the medium-pressure zone storage tank 10 supplies liquid to the low-pressure zone buffer tank 18; the liquid inlet of each medium-pressure zone storage tank 10 A second on-off valve 122 for controlling whether the total inlet port 17 supplies liquid to the intermediate-pressure zone storage tank 10 is provided; the intermediate-pressure air supply valve 151 is provided on the air supply pipe 16 of each medium-pressure zone storage tank 10, and the low-pressure zone buffer is provided.
  • a low pressure air supply valve 152 is provided on the air supply pipe 16 of the tank 18.
  • An air pressure detector is disposed in the medium pressure zone storage tank 10 and the low pressure zone buffer tank 18.
  • the barometer detects the working pressure in the tank in real time.
  • a safety relief valve 25 is also disposed in the medium pressure zone storage tank 10 and the low pressure zone buffer tank 18.
  • the safety relief valve 25 can discharge the shielding gas containing BOG or the gaseous natural gas in time to avoid the air pressure in the tank is too high, and the safety release valve 25 can also filter and recover the BOG. Or gaseous natural gas to avoid environmental pollution and waste of resources.
  • a control system for a floating liquefied natural gas storage and gasification device for controlling a floating liquefied natural gas storage and gasification device to continuously supply high-pressure gaseous natural gas to a gas-using device, the control system comprising a switch control unit, a gas pressure detecting unit and a processing unit;
  • the unit includes a first on-off valve 121 for controlling whether the medium-pressure zone storage tanks 10 supply liquid to the low-pressure zone buffer tank 18, a second on-off valve 122 for controlling whether the total liquid inlet port 17 supplies liquid to the intermediate-pressure zone storage tank 10, a medium pressure air supply valve 151 for controlling the working air pressure in each medium pressure zone storage tank 10, and a low pressure air supply valve 152 for controlling the working air pressure in the low pressure area buffer tank 18;
  • the air pressure detecting unit includes a storage tank 10 disposed in each medium pressure zone And the air pressure detector in the low pressure zone buffer tank 18, the air pressure detector detects the working air pressure values in the medium pressure zone storage tank 10 and the low pressure zone buffer tank 18 in real
  • the processing unit includes a PLC controller that controls switching operations of each of the first switching valve 121, the second switching valve 122, the intermediate pressure air supply valve 151, and the low pressure air supply valve 152; the air pressure detecting unit is disposed in each medium pressure zone storage tank 10
  • the working air pressure value and the working air pressure value in the low pressure zone buffer tank 18 are sent to the processing unit; the processing unit selects a medium pressure zone storage tank 10 and the low pressure area buffer tank 18 to be turned on by controlling the first switching valve 121, and the processing unit passes the selection.
  • the medium pressure air supply valve 151 of the medium pressure zone storage tank 10 controls the working air pressure P1 of the medium pressure zone storage tank 10 to always be greater than the working air pressure P2 of the low pressure zone storage tank.
  • the control system controls the air pressure of each medium-pressure zone storage tank 10 and the low-pressure zone buffer tank 18 and the flow of LNG through each of the on-off valve and the supplemental gas valve, and has the advantages of convenient control and remote control and automatic control.
  • the processing unit controls the working pressure P1 in the medium pressure zone storage tank 10 to remain within the working pressure range: Pa ⁇ P1 ⁇ Pb; Pa is the lower working pressure limit of the medium pressure zone storage tank 10, when P1 is lower than Pa, the middle
  • the pressure-compensating gas valve 151 is opened, the gas supply pipe 16 is filled with gas into the medium pressure zone storage tank 10; Pb is the upper working pressure upper limit of the medium pressure zone storage tank 10, and when P1 is higher than Pb, the medium pressure air supply valve 151 is closed, The trachea 16 stops qi.
  • the working pressure P2 of the low pressure zone buffer tank 18 is maintained within the working pressure range: Pc ⁇ P2 ⁇ Pd; Pc is the lower working pressure limit of the low pressure zone buffer tank 18, and when P2 is lower than Pc, the low pressure makeup valve 152 is opened.
  • the air supply pipe 16 is filled with gas into the low pressure zone buffer tank 18; Pd is the upper limit of the working air pressure of the low pressure zone buffer tank 18, when P2 is higher than Pd, the low pressure air supply valve 152 is closed, and the air supply pipe 16 stops the air supply.
  • the medium pressure air supply valve 151 and the low pressure air supply valve 152 are pneumatic on-off valves.
  • the first switching valve 121, the second switching valve 122, the intermediate pressure air supply valve 151, and the low pressure air supply valve 152 are normally closed switching valves.
  • the processing unit selects the target medium pressure zone storage tank 10 only the first switching valve 121 or the second switching valve 122 or the intermediate pressure air supply valve 151 needs to be opened, so that the corresponding operation of the target medium pressure zone storage tank 10 can be realized. .
  • the processing unit further includes a wireless communication module, the processing unit is connected to the remote server through the wireless communication module, the remote server is connected to the intelligent terminal, and the intelligent terminal acquires data in the processing unit through the remote server and the wireless communication module, and the intelligent terminal passes through the remote server.
  • the wireless communication module and the processing unit control the switching action of the switch control unit. Remote control of floating LNG storage and gasification devices is achieved through smart terminals such as mobile phones and laptops.
  • the method for controlling a floating liquefied natural gas storage and gasification device comprises the following steps:
  • the LNG carrier is connected to the total inlet port 17 of the hull 23, the high-pressure natural gas outlet 22 of the hull 23 is connected to the gas-using equipment, and the processing unit sequentially opens the second switching valve 122 to input the LNG into the medium-pressure zone storage tank 10,
  • the working pressure P1 of the medium pressure zone storage tank 10 is: Pa-Pb
  • the working pressure P2 of the low pressure zone buffer tank 18 is: Pc-Pd, wherein Pb>Pa>Pd>Pc;
  • the processing unit selects a medium pressure zone storage tank 10 as a working storage tank by controlling the switching action of each first switching valve 121, and the LNG flows from the working storage tank into the low pressure zone buffer tank 18 under the action of the working air pressure difference;
  • the submersible pump 19 continuously transports the LNG in the submerged pump box 20 to the LNG gasification device 21;
  • the LNG gasification device 21 continuously supplies high-pressure gaseous natural gas to the gas-using equipment;
  • the medium pressure air supply valve 151 when the working pressure P1 of the working storage tank is lower than Pa, the medium pressure air supply valve 151 is opened, and the air supply pipe 16 is supplied to the medium pressure zone storage tank 10, and the working pressure P1 of the medium pressure zone storage tank 10 is higher than Pb.
  • the medium pressure air supply valve 151 is closed, and the air supply pipe 16 stops the air supply;
  • the low pressure air supply valve 152 When the working air pressure P2 of the low pressure zone buffer tank 18 is lower than Pc, the low pressure air supply valve 152 is opened, and the air supply pipe 16 is supplied to the low pressure zone buffer tank 18, and when the working pressure P2 of the low pressure zone buffer tank 18 is higher than Pd, the low pressure is low.
  • the air supply valve 152 is closed, and the air supply pipe 16 stops the air supply.
  • step S7 the processing unit closes the first switching valve 121 of the working storage tank, and the processing unit selects another intermediate pressure zone storage tank 10 as a new working storage tank by controlling the switching action of each of the first switching valves 121.
  • the control method enables a floating LNG storage and regasification system to provide continuous high pressure gaseous natural gas to users and power plants.
  • the processing unit selects the working tank in such a manner that the first switching valve 121 of the target medium nip tank 10 is opened and the first switching valve 121 of the remaining medium nip tank 10 is closed.

Abstract

一种为港口天然气用户及发电厂连续不间断提供天然气燃料的浮式存储和气化装置，包括设置在船体（23）上的至少一个中压区储罐（10），及与中压区储罐（10）顺次连接的低压区缓冲罐（18）、潜液泵箱（20）及LNG气化装置（21），采用外层为碳钢材质的低成本中压区储罐（10）的出液口设置在罐体顶部，通过中压区储罐（10）与低压区缓冲罐（18）之间的工作气压压差实现LNG的连续流动，进而实现高压气态天然气的连续不间断供应。该浮式液化天然气存储和气化装置具有停靠方便、制造成本低，可实现连续供气及控制简单等优点。

Description

浮式液化天然气存储和气化装置、控制系统及控制方法 技术领域
本发明属于LNG存储、运输及气化技术领域，尤其是涉及一种为港口天然气用户及发电厂连续不间断提供天然气燃料的浮式存储和气化装置，包括该存储和气化装置的控制系统和控制方法。
背景技术
LNG是液化天然气(Liquefied Natural Gas)的缩写，其主要成分是甲烷。LNG是通过在常压下气态的天然气冷却至-162℃，使之凝结成液体，天然气液化后可以大大节约储运空间，具有热值大、性能高等特定。
LNG是一种清洁、高效的能源，很多国家都将LNG列为首选燃料，天然气在能源供应中的比例迅速增加，LNG将成为石油之后下一个全球争夺的热门能源商品。
LNG的水路运输能大大减少运输成本，但是，现有的LNG运输船舶吨位较大，只能进入各类港口，无法近距离停靠海岸，无法与用户直接对接匹配。现有的LNG存储装置需要占据一定的土地，在实际应用中存在建设周期长、可移动性差、土地使用成本高等问题。
发明内容
有鉴于此，本发明旨在提出一种浮式液化天然气存储和气化装置、控制系统及控制方法，以解决现有的用户及发电厂使用LNG时，存在的占用土地、建设周期长、可移动性差及能源成本较高等问题。
为达到上述目的，本发明的技术方案是这样实现的：
浮式液化天然气存储和气化装置，包括船体，船体上设置有至少一个中压区储罐，中压区储罐依次与低压区缓冲罐、潜液泵箱及LNG气化装置连接；
中压区储罐的出液口位于罐体顶部，低压区缓冲罐的出液口位于LNG底部， 液体输出管路一端自中压区储罐的出液口延伸至LNG底部，液体输出管路的另一端与低压区缓冲罐连接；
中压区储罐及低压区缓冲罐内均设置有补气管，通过补气管控制罐体内的工作气压，中压区储罐的工作气压的下限高于低压区缓冲罐工作气压的上限，通过工作气压的压力差，中压区储罐向低压区缓冲罐提供连续LNG；
低压区缓冲罐底部通过液体输出管路与潜液泵箱的入液口连接，低压区缓冲罐的空腔通过通气管路与潜液泵箱的空腔导通，通气管路使低压区缓冲罐的工作气压与潜液泵箱的工作气压始终相同，流入低压区缓冲罐的LNG连续流入潜液泵箱；
潜液泵箱通过潜液泵向LNG气化装置提供连续的LNG，LNG气化装置向用气设备提供连续的高压气态天然气。
进一步的，中压区储罐为真空双层储液罐或单层承压储液罐，低压区缓冲罐为真空双层缓冲罐或单层承压缓冲罐。
进一步的，真空双层储液罐的外层罐体为碳钢材质，真空双层储液罐的内层罐体为不锈钢材质；单层承压储液罐的罐体为不锈钢材质，外围缠绕保温材料，单层承压缓冲罐的罐体为不锈钢材质，外围缠绕保温材料；真空双层缓冲罐的外层罐体为不锈钢材质，真空双层缓冲罐的内层罐体为不锈钢材质。
进一步的，真空双层储液罐、真空双层缓冲罐、单层承压储液罐及单层承压缓冲罐均为C型储罐。
进一步的，所述船体上设置有至少两个中压区储罐，中压区储罐的入液口位于罐体顶部，各中压区储罐通过液体输入管路与总进液口并联连接，总进液口通过液体输入管路向中压区储罐提供LNG，各中压区储罐通过液体输出管路与低压区缓冲罐并联连接。
进一步的，所述液体输入管路为钢管或软管，液体输出管路为钢管或软管。
进一步的，所述中压区储罐的入液口上设有上进液喷淋头。
进一步的，所述各中压区储罐的出液口处设有控制中压区储罐是否向低压区 缓冲罐供液的第一开关阀；各中压区储罐的入液口处设有控制总进液口是否向中压区储罐供液的第二开关阀；各中压区储罐的补气管上设有中压补气阀，低压区缓冲罐的补气管上设有低压补气阀。
进一步的，所述中压区储罐及低压区缓冲罐内均设置有气压检测计。
进一步的，所述中压区储罐及低压区缓冲罐内还设有安全放散阀。
浮式液化天然气存储和气化装置的控制系统，包括开关控制单元、气压检测单元和处理单元；
开关控制单元，包括控制各中压区储罐是否向低压区缓冲罐供液的第一开关阀、控制总进液口是否向中压区储罐供液的第二开关阀、控制各中压区储罐内工作气压的中压补气阀、及控制低压区缓冲罐内工作气压的低压补气阀；
气压检测单元，包括设置在各中压区储罐及低压区缓冲罐内的气压检测计，气压检测计实时检测各中压区储罐及低压区缓冲罐内的工作气压值；
处理单元，包括控制各第一开关阀、第二开关阀、中压补气阀及低压补气阀开关动作的PLC控制器；
气压检测单元将每个中压区储罐内的工作气压值及低压区缓冲罐内的工作气压值发送至处理单元；
处理单元通过控制第一开关阀选择一个中压区储罐与低压区缓冲罐导通，处理单元通过选中的中压区储罐的中压补气阀控制该中压区储罐的工作气压P1始终大于低压区储罐的工作气压P2。
进一步的，所述处理单元控制中压区储罐内的工作气压P1保持在工作气压范围之内：Pa<P1<Pb；Pa为中压区储罐的工作气压下限，P1低于Pa时，中压补气阀打开，补气管向中压区储罐内补入气体；Pb为中压区储罐的工作气压上限，P1高于Pb时，中压补气阀关闭，补气管停止补气。
进一步的，所述低压区缓冲罐的工作气压P2保持在工作气压范围之内：Pc<P2<Pd；Pc为低压区缓冲罐的工作气压下限，P2低于Pc时，低压补气阀打开，补气管向低压区缓冲罐内补入气体；Pd为低压区缓冲罐的工作气压上限，P2高 于Pd时，低压补气阀关闭，补气管停止补气。
进一步的，所述中压补气阀和低压补气阀为气动开关阀。
进一步的，所述第一开关阀、第二开关阀、中压补气阀及低压补气阀均为常闭开关阀。
进一步的，所述处理单元还包括无线通信模块，处理单元通过无线通信模块与远程服务器连接，远程服务器与智能终端连接，智能终端通过远程服务器、无线通信模块获取处理单元中的数据，智能终端通过远程服务器、无线通信模块、处理单元控制开关控制单元的开关动作。
浮式液化天然气存储和气化装置的控制方法，包括如下步骤：
S1，LNG运输船与船体的总进液口连接，船体的高压天然气出口与用气设备连接，处理单元依次打开第二开关阀向各中压区储罐内输入LNG，中压区储罐的工作气压P1范围为：Pa-Pb，低压区缓冲罐的工作气压P2范围为：Pc-Pd，其中，Pb>Pa>Pd>Pc；
S2，处理单元通过控制各第一开关阀开关动作选择一个中压区储罐作为工作储罐，LNG在工作气压差的作用下自工作储罐流入低压区缓冲罐；
S3，通过通气管路使低压区缓冲罐的工作气压与潜液泵箱的工作气压始终相同，流入低压区缓冲罐的LNG连续流入潜液泵箱；
S4，潜液泵将潜液泵箱内的LNG持续输送至LNG气化装置内；
S5，LNG气化装置持续向用气设备提供高压气态天然气；
S6，工作储罐的工作气压P1低于Pa时，中压补气阀打开，补气管向中压区储罐内补气，当中压区储罐的工作气压P1高于Pb时，中压补气阀关闭，补气管停止补气；
低压区缓冲罐的工作气压P2低于Pc时，低压补气阀打开，补气管向低压区缓冲罐内补气，当低压区缓冲罐的工作气压P2高于Pd时，低压补气阀关闭，补气管停止补气。
进一步的，还包括步骤S7，处理单元关闭工作储罐的第一开关阀，处理单 元通过控制各第一开关阀的开关动作选择另一个中压区储罐作为新工作储罐。
进一步的，处理单元选择工作储罐的方式为：打开目标中压区储罐的第一开关阀并关闭其余中压区储罐的第一开关阀。
相对于现有技术，本发明所述的浮式液化天然气存储和气化装置、控制系统及控制方法具有以下优势：
(1)本发明所述的浮式液化天然气存储和气化装置，船上设置多个中压区储罐，中压区储罐为真空双层储液罐，设计合理的载重量，使船体可停靠在水深较小的岸边，吃水深度最小在3-4米之间，方便与用户及发电厂对接，既解决了大型运输船舶只能停靠在港口等深水区域的问题，又避免了天然气存储和气化装置需要占用土地的问题；
为了应对行业标准IGC要求，需要储液罐出液口位于上部，为了出液口位于上部的储液罐向潜液泵箱连续供液，设置真空双层缓冲罐，真空双层缓冲罐的罐体较小，因而对设备整体的成本控制是合理的，通过真空双层缓冲罐实现设备对潜液泵箱及LNG气化装置连续供液，进而实现对用户或发电厂提供连续高压气态天然气；
采用上进液喷淋的方式可减少中压区储罐BOG(Boil Off Gas，闪蒸气)的产生，增加LNG的储藏时间；
外置的潜液泵，制造、安装及维护的成本低、耗电量少、运行平稳；C型储罐制造方便、耐用，保温性好。
(2)本发明所述的浮式液化天然气存储和气化装置的控制系统，可通过各个开关阀及补气阀控制各个中压区储罐、低压区缓冲罐的气压及LNG的流动，具有控制方便及可实现远程控制、自动控制的优点。
(3)本发明所述的浮式液化天然气存储和气化装置的控制方法，可实现浮式液化天然气存储和再气化系统为用户和发电厂提供连续的高压气态天然气。
附图说明
构成本发明创造的一部分的附图用来提供对本发明创造的进一步理解，本发 明创造的示意性实施例及其说明用于解释本发明创造，并不构成对本发明创造的不当限定。在附图中：
图1为本发明实施例所述的浮式液化天然气存储和气化装置的结构示意图；
图2为本发明实施例所述的浮式液化天然气存储和气化装置的压力分区示意图。
附图标记说明：
10-中压区储罐；11-液体输出管路；121-第一开关阀；122-第二开关阀；13-上进液喷淋头；14-液体输入管路；151-中压补气阀；152-低压补气阀；16-补气管；17-总进液口；18-低压区缓冲罐；19-潜液泵；20-潜液泵箱；21-LNG气化装置；22-高压天然气出口；23-船体；24-通气管路；25-安全放散阀。
具体实施方式
需要说明的是，在不冲突的情况下，本发明创造中的实施例及实施例中的特征可以相互组合。
在本发明创造的描述中，需要理解的是，术语“中心”、“纵向”、“横向”、“上”、“下”、“前”、“后”、“左”、“右”、“竖直”、“水平”、“顶”、“底”、“内”、“外”等指示的方位或位置关系为基于附图所示的方位或位置关系，仅是为了便于描述本发明创造和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本发明创造的限制。此外，术语“第一”、“第二”等仅用于描述目的，而不能理解为指示或暗示相对重要性或者隐含指明所指示的技术特征的数量。由此，限定有“第一”、“第二”等的特征可以明示或者隐含地包括一个或者更多个该特征。在本发明创造的描述中，除非另有说明，“多个”的含义是两个或两个以上。
在本发明创造的描述中，需要说明的是，除非另有明确的规定和限定，术语“安装”、“相连”、“连接”应做广义理解，例如，可以是固定连接，也可以是可拆卸连接，或一体地连接；可以是机械连接，也可以是电连接；可以是直接相连，也可以通过中间媒介间接相连，可以是两个元件内部的连通。对于本领域的普通技术人员而言，可以通过具体情况理解上述术语在本发明创造中的具体含 义。
下面将参考附图并结合实施例来详细说明本发明创造。
本技术方案所要解决的技术问题主要有：
1，现有的LNG运输船舶吨位较大，只能进入港口而无法停靠在水深较浅的海岸边，无法与用气设备直接连接，需要中转设备，增加了天然气用气成本；
2，除了设备成本，天然气中转设备需要占用土地，造成天然气用气成本进一步升高；
3，现有的LNG运输船舶、周转船舶等设备，受到行业标准的限制和要求，需要采用真空双层储液罐或单层承压储液罐，特别是装载在船舶等海上设施上的真空双层储液罐，对储罐的出液方式有具体要求：
当采用内外双层均为不锈钢的真空双层储液罐时，可采用下出液方式，该下出液方式利用LNG的重力可实现中压区储罐10向潜液泵箱20提供连续的LNG，但是，真空双层储液罐的内外层均为不锈钢材质时，会造成储液罐成本很高，特别是随着真空双层储液罐的体积增大，成本也将成倍增加。
当采用内层为不锈钢材质、外层为碳钢等保温材质的真空双储液罐时，储液罐的成本可得到有效控制，(碳钢等保温材质的成本远低于不锈钢材质)但是，根据行业标准IGC要求，此形式的真空双层储液罐出液口必须设置在罐体顶部，需要将LNG从顶部抽出。如何将LNG抽出并向LNG气化装置21连续供液，是本发明所要解决的核心问题之一。上述行业标准具体为IGC要求(IGC MSC.370(93)_the latest version of IGC Code)。
为了向海岸边的发电厂等用户提供连续的高压气态天然气，本发明提供了一种不占用土地的浮式液化天然气存储和气化装置，如图1所示，该系统包括船体23，该船体23的最小吃水深度在3-4米之间，船体23可方便停靠在大部分的海岸边，既解决了大型船舶无法与用户直接对接的问题，还解决了天然气中转设备需要占用土地的问题，极大降低了高压天然气的用气成本；
船体23上设置有至少一个中压区储罐10，该中压区储罐10为真空双层储 液罐，真空双层储液罐是存储、运输液化天然气的通用设备，大型的真空双层储液罐制造成本极高，本发明通过使用多个较小的真空双层储液罐分别存储LNG来降低储罐的使用成本，船体23上通常设置4-8个真空双层储液罐，易知，本技术方案对真空双层储液罐的数量并不作限定。船体23上设置多个真空双层储液罐，设计合理的载重量，使得承载真空双层储液罐的船体23可以停靠在水深较小的岸边，方便与发电厂对接。
本技术方案所要解决的如何将LNG抽出并向LNG气化装置21连续供液这一核心问题还可拆解为若干连续的小问题，第一，如何将LNG自中压区储罐10中连续抽出；第二，如何将抽出的LNG连续供应至LNG气化装置中；第三，采用外置潜液泵19和潜液泵箱20时，如何保证潜液泵19的正常工作，即潜液泵箱20液面的控制和潜液泵箱20工作气压的控制，如果进入潜液泵箱20的LNG速度过快，导致潜液泵箱20液面升高过快，潜液泵箱20内工作气压过高会导致LNG无法流入或潜液泵19工作异常，如果流入的LNG速度过慢，潜液泵箱20液面下降露出潜液泵19，会导致潜液泵19损坏，即中压区储罐10与潜液泵箱20的供液配合是很难解决的问题；第四，潜液泵箱20中的空腔通常需要与一个储液腔体导通，用来排出BOG，如果采用中压区储罐10与潜液泵箱20配合，则潜液泵箱20的空腔找不到合适的储液腔体配合，如果单独配置储液腔体，则造成成本不必要的上升；第五，如何实现在中压区储罐10、低压区缓冲罐18、潜液泵箱20之间形成LNG液体流动的简单控制和自动控制。
现有的大型LNG储液罐采用上出液口式时，通常采用潜液泵19抽出LNG的方式，但是，由于LNG本身比重轻，温度低，对潜液泵19有非常高的要求，一套潜液泵19设备的成本往往高达数百万，对天然气的用气成本控制非常不利。特别的，本方案中使用的真空双层储液罐，外层使用碳钢，内层使用不锈钢，由于罐体壁比较薄，很难在罐内设置潜液泵19及配套支架等设备，所以，本方案中无论是从成本考虑还是从实际技术角度考虑，都不倾向于选择内置潜液泵19抽出LNG的方式。
本技术方案中，船体23上设置有至少一个中压区储罐10，中压区储罐10依次与低压区缓冲罐18、潜液泵箱20及LNG气化装置21连接；中压区储罐10 的出液口位于罐体顶部，低压区缓冲罐18的出液口位于LNG底部，液体输出管路11一端自中压区储罐10的出液口延伸至LNG底部，液体输出管路11的另一端与低压区缓冲罐18连接；
本技术方案中，设置了低压区缓冲罐18，该低压区缓冲罐18为真空双层缓冲罐，真空双层缓冲罐的内外双层均为不锈钢材质，为了控制这种成本较高的储罐，真空双层缓冲罐仅设置一个，且真空双层缓冲罐体积较小，其成本相对较低。
由于所有的真空双层储液罐中均设定一定的工作气压，真空双层缓冲罐也有一定的工作气压范围，可将真空双层储液罐的工作气压始终高于真空双层缓冲罐，利用压力差将LNG输送到真空双层缓冲罐中。该压力差即利用压力差将LNG自真空双层储液罐中抽出。
将LNG自中压区储罐10抽至低压区缓冲罐18中后，潜液泵19如果设置在低压区缓冲罐18内部，则仍然存在内置潜液泵19所存在的成本、维护、维修等问题，特别是，潜液泵19一旦出现问题更换时需要停机，导致LNG连续供应的中断，故需要使用单独潜液泵箱20，即形成中压区储罐10、低压区缓冲罐18和潜液泵箱20的连续连接。外置的潜液泵19，制造、安装及维护的成本低、耗电量少、运行平稳。
进一步的，外置的潜液泵19还存在很大问题，在实际运行中很难正常运行并达到连续供液LNG的目的，问题主要有潜液泵箱20液面的控制和潜液泵箱20工作气压的控制，以及潜液泵箱20BOG排放的问题，但是，通过设置真空双层缓冲罐及将真空双层缓冲罐和潜液泵箱20的空腔导通则完美解决了这一系列问题。
真空双层缓冲罐的作用包括：1，向前与真空双层储液罐配合将LNG抽出；2，先后与潜液泵箱20配合，真空双层缓冲罐的出液口设置在LNG底部，恢复了常规的、利用重力的连续LNG供液，由于真空双层缓冲罐通过通气管路24与潜液泵箱20导通，真空双层缓冲罐可同时调整潜液泵箱20的液面和工作气压。例如，LNG快速流入真空双层缓冲罐时，液面升高速度相对较慢，潜液泵箱20内的液面升高速度也相对较慢，这解决了潜液泵箱20体积小，对LNG流速非常敏感和难于控制的问题；3，由于真空双层缓冲罐带有安全放散阀25，还可将潜液泵箱20内的BOG排出。
通气管路24的作用包括：1，导通真空双层缓冲罐和潜液泵箱20，使得真空双层缓冲罐可利用LNG自重实现LNG自动流入潜液泵箱20；2，造成真空双层储液罐、真空双层缓冲罐、潜液泵箱20之间形成自高而低三级压力，这种设计方法造成各压力范围内的设备工作气压范围过窄，设备需要频繁开关，设计成本高，设施损耗大，本方案采用通气管路24将真空双层缓冲罐和潜液泵箱20导通，使真空双层缓冲罐和潜液泵箱20的工作气压始终相同，将三级压力简化为二级压力，还省去了潜液泵箱20内的气压控制设备，由于真空双层缓冲罐和潜液泵箱20的工作气压始终相同，流入真空双层缓冲罐的LNG自动流到潜液泵箱20中。3，可将潜液泵箱20内的BOG导出到真空双层缓冲罐，并利用真空双层缓冲罐的安全放散阀25排出BOG。
自此，完整的LNG连续供液方案完成，在一种优选实施例中：
如图2所示，浮式液化天然气存储和气化装置，包括船体23，船体23上设置至少一个真空双层储液罐，每个真空双层储液罐与真空双层缓冲罐连接，真空双层缓冲罐与潜液泵箱20连接，潜液泵箱20与LNG气化装置21连接；真空双层储液罐的出液口位于罐体顶部，真空双层缓冲罐的出液口位于LNG底部，液体输出管路11一端自真空双层储液罐的出液口延伸至LNG底部，另一端与真空双层缓冲罐连接；真空双层储液罐与真空双层缓冲罐均设置有补气管16，通过补气管16控制真空双层储液罐的工作气压始终大于真空双层缓冲罐，利用该压力差，真空双层储液罐通过液体输出管路11向真空双层缓冲罐提供连续LNG；通气管路24导通真空双层缓冲罐与潜液泵箱20使二者的工作气压始终相同，流入真空双层缓冲罐的LNG连续流入潜液泵箱20；潜液泵箱20通过潜液泵19向LNG气化装置21提供连续的LNG，LNG气化装置21向用气设备提供连续的高压气态天然气。
各中压区储罐10的压力处于中压区范围，真空双层缓冲罐和潜液泵箱20处于低压区范围。
该实施例的技术方案具有如下优势：船上设置多个中压区储罐10，中压区储罐10为真空双层储液罐，设计合理的载重量，使船体23可停靠在水深较小的岸边，吃水深度最小在3-4米之间，方便与用户及发电厂对接，既解决了大型运 输船舶只能停靠在港口等深水区域的问题，又避免了天然气存储和气化装置需要占用土地的问题；真空双层储液罐采用成本较低的外层为碳钢或其他保温材料、内层为不锈钢的罐体，在相同体积下，由于碳钢罐体的成本远低于不锈钢罐体，所以本方案避免使用大型的、价格高昂的大型储液罐，在承载相同LNG重量下，本装置的成本为内外双层均为不锈钢大型储液罐的船体23的10％左右；通过真空双层缓冲罐实现设备对潜液泵箱20及LNG气化装置21连续供液，进而实现对用户或发电厂提供连续高压气态天然气。
上述真空双层储液罐及真空双层缓冲罐也可以设置成单层承压储液罐及单层承压缓冲罐，具体的，单层承压储液罐的罐体为不锈钢材质，外围缠绕保温材料，单层承压缓冲罐的罐体为不锈钢材质，外围缠绕保温材料。
真空双层储液罐、真空双层缓冲罐、单层承压储液罐及单层承压缓冲罐均为C型储罐。C型储罐制造方便、耐用，保温性好。
所述船体23上设置有至少两个中压区储罐10，中压区储罐10的入液口位于罐体顶部，各中压区储罐10通过液体输入管路14与总进液口17并联连接，总进液口17通过液体输入管路14向中压区储罐10提供LNG，总进液口17可同时向多个中压区储罐10提供LNG，也可向单独中压区储罐10提供LNG，各中压区储罐10通过液体输出管路11与低压区缓冲罐18并联连接，每次选定某一个中压区储罐10向低压区缓冲罐18提供LNG。
所述液体输入管路14为钢管或软管，液体输出管路11为钢管或软管。
如图2所示，所述中压区储罐10的入液口上设有上进液喷淋头13。采用上进液喷淋的方式可减少中压区储罐10BOG的产生，增加LNG的储藏时间。
所述各中压区储罐10的出液口处设有控制中压区储罐10是否向低压区缓冲罐18供液的第一开关阀121；各中压区储罐10的入液口处设有控制总进液口17是否向中压区储罐10供液的第二开关阀122；各中压区储罐10的补气管16上设有中压补气阀151，低压区缓冲罐18的补气管16上设有低压补气阀152。
所述中压区储罐10及低压区缓冲罐18内均设置有气压检测计。气压检测计实时检测罐体内的工作气压值。
所述中压区储罐10及低压区缓冲罐18内还设有安全放散阀25。在LNG流入中压区储罐10或低压区缓冲罐18时，安全放散阀25可将含有BOG的保护气体或气态天然气及时排出，避免罐体内气压过高，安全放散阀25还可以过滤回收BOG或气态天然气，避免其对环境的污染和造成资源浪费。
浮式液化天然气存储和气化装置的控制系统，用于控制浮式液化天然气存储和气化装置向用气设备连续提供高压气态天然气，该控制系统包括开关控制单元、气压检测单元和处理单元；开关控制单元，包括控制各中压区储罐10是否向低压区缓冲罐18供液的第一开关阀121、控制总进液口17是否向中压区储罐10供液的第二开关阀122、控制各中压区储罐10内工作气压的中压补气阀151、及控制低压区缓冲罐18内工作气压的低压补气阀152；气压检测单元，包括设置在各中压区储罐10及低压区缓冲罐18内的气压检测计，气压检测计实时检测各中压区储罐10及低压区缓冲罐18内的工作气压值；气压检测单元还包括将工作气压值发送至处理单元的信号发送单元。
处理单元，包括控制各第一开关阀121、第二开关阀122、中压补气阀151及低压补气阀152开关动作的PLC控制器；气压检测单元将每个中压区储罐10内的工作气压值及低压区缓冲罐18内的工作气压值发送至处理单元；处理单元通过控制第一开关阀121选择一个中压区储罐10与低压区缓冲罐18导通，处理单元通过选中的中压区储罐10的中压补气阀151控制该中压区储罐10的工作气压P1始终大于低压区储罐的工作气压P2。
该控制系统通过各个开关阀及补气阀控制各个中压区储罐10、低压区缓冲罐18的气压及LNG的流动，具有控制方便及可实现远程控制、自动控制的优点。
所述处理单元控制中压区储罐10内的工作气压P1保持在工作气压范围之内：Pa<P1<Pb；Pa为中压区储罐10的工作气压下限，P1低于Pa时，中压补气阀151打开，补气管16向中压区储罐10内补入气体；Pb为中压区储罐10的工作气压上限，P1高于Pb时，中压补气阀151关闭，补气管16停止补气。
所述低压区缓冲罐18的工作气压P2保持在工作气压范围之内：Pc<P2<Pd；Pc为低压区缓冲罐18的工作气压下限，P2低于Pc时，低压补气阀152打开，补气管16向低压区缓冲罐18内补入气体；Pd为低压区缓冲罐18的工作气压上 限，P2高于Pd时，低压补气阀152关闭，补气管16停止补气。
所述中压补气阀151和低压补气阀152为气动开关阀。
所述第一开关阀121、第二开关阀122、中压补气阀151及低压补气阀152均为常闭开关阀。处理单元选择目标中压区储罐10时，仅需打开其第一开关阀121或第二开关阀122或中压补气阀151，即可实现对该目标中压区储罐10的相应操作。
所述处理单元还包括无线通信模块，处理单元通过无线通信模块与远程服务器连接，远程服务器与智能终端连接，智能终端通过远程服务器、无线通信模块获取处理单元中的数据，智能终端通过远程服务器、无线通信模块、处理单元控制开关控制单元的开关动作。通过智能终端，如手机、手提电脑等实现对浮式液化天然气存储和气化装置的远程控制。
浮式液化天然气存储和气化装置的控制方法，包括如下步骤：
S1，LNG运输船与船体23的总进液口17连接，船体23的高压天然气出口22与用气设备连接，处理单元依次打开第二开关阀122向各中压区储罐10内输入LNG，中压区储罐10的工作气压P1范围为：Pa-Pb，低压区缓冲罐18的工作气压P2范围为：Pc-Pd，其中，Pb>Pa>Pd>Pc；
S2，处理单元通过控制各第一开关阀121开关动作选择一个中压区储罐10作为工作储罐，LNG在工作气压差的作用下自工作储罐流入低压区缓冲罐18；
S3，通过通气管路24使低压区缓冲罐18的工作气压与潜液泵箱20的工作气压始终相同，流入低压区缓冲罐18的LNG连续流入潜液泵箱20；
S4，潜液泵19将潜液泵箱20内的LNG持续输送至LNG气化装置21内；
S5，LNG气化装置21持续向用气设备提供高压气态天然气；
S6，工作储罐的工作气压P1低于Pa时，中压补气阀151打开，补气管16向中压区储罐10内补气，当中压区储罐10的工作气压P1高于Pb时，中压补气阀151关闭，补气管16停止补气；
低压区缓冲罐18的工作气压P2低于Pc时，低压补气阀152打开，补气管 16向低压区缓冲罐18内补气，当低压区缓冲罐18的工作气压P2高于Pd时，低压补气阀152关闭，补气管16停止补气。
还包括步骤S7，处理单元关闭工作储罐的第一开关阀121，处理单元通过控制各第一开关阀121的开关动作选择另一个中压区储罐10作为新工作储罐。
该控制方法可实现浮式液化天然气存储和再气化系统为用户和发电厂提供连续的高压气态天然气。
处理单元选择工作储罐的方式为：打开目标中压区储罐10的第一开关阀121并关闭其余中压区储罐10的第一开关阀121。
以上所述仅为本发明创造的较佳实施例而已，并不用以限制本发明创造，凡在本发明创造的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本发明创造的保护范围之内。

Claims (13)

  1. 浮式液化天然气存储和气化装置，其特征在于：包括船体(23)，船体(23)上设置有至少一个中压区储罐(10)，中压区储罐(10)依次与低压区缓冲罐(18)、潜液泵箱(20)及LNG气化装置(21)连接；
    中压区储罐(10)的出液口位于罐体顶部，低压区缓冲罐(18)的出液口位于LNG底部，液体输出管路(11)一端自中压区储罐(10)的出液口延伸至LNG底部，液体输出管路(11)的另一端与低压区缓冲罐(18)连接；
    中压区储罐(10)及低压区缓冲罐(18)内均设置有补气管(16)，通过补气管(16)控制罐体内的工作气压，中压区储罐(10)的工作气压的下限高于低压区缓冲罐(18)工作气压的上限，通过工作气压的压力差，中压区储罐(10)向低压区缓冲罐(18)提供连续LNG；
    低压区缓冲罐(18)底部通过液体输出管路(11)与潜液泵箱(20)的入液口连接，低压区缓冲罐(18)的空腔通过通气管路(24)与潜液泵箱(20)的空腔导通，通气管路(24)使低压区缓冲罐(18)的工作气压与潜液泵箱(20)的工作气压始终相同，流入低压区缓冲罐(18)的LNG连续流入潜液泵箱(20)；
    潜液泵箱(20)通过潜液泵(19)向LNG气化装置(21)提供连续的LNG，LNG气化装置(21)向用气设备提供连续的高压气态天然气。
  2. 根据权利要求1所述的浮式液化天然气存储和气化装置，其特征在于：船体(23)上设置有至少两个中压区储罐(10)，中压区储罐(10)的入液口位于罐体顶部，各中压区储罐(10)通过液体输入管路(14)与总进液口(17)并联连接，总进液口(17)通过液体输入管路(14)向中压区储罐(10)提供LNG，各中压区储罐(10)通过液体输出管路(11)与低压区缓冲罐(18)并联连接；
    中压区储罐(10)的入液口上设有上进液喷淋头(13)。
  3. 根据权利要求2所述的浮式液化天然气存储和气化装置，其特征在于：
    各中压区储罐(10)的出液口处设有控制中压区储罐(10)是否向低压区缓冲罐(18)供液的第一开关阀(121)；
    各中压区储罐(10)的入液口处设有控制总进液口(17)是否向中压区储罐(10)供液的第二开关阀(122)；
    各中压区储罐(10)的补气管(16)上设有中压补气阀(151)，低压区缓冲罐(18)的补气管(16)上设有低压补气阀(152)。
  4. 根据权利要求1所述的浮式液化天然气存储和气化装置，其特征在于：中压区储罐(10)及低压区缓冲罐(18)内均设置有气压检测计。
  5. 根据权利要求1所述的浮式液化天然气存储和气化装置，其特征在于：中压区储罐(10)及低压区缓冲罐(18)内还设有安全放散阀(25)。
  6. 浮式液化天然气存储和气化装置的控制系统，其特征在于：包括开关控制单元、气压检测单元和处理单元；
    开关控制单元，包括控制各中压区储罐(10)是否向低压区缓冲罐(18)供液的第一开关阀(121)、控制总进液口(17)是否向中压区储罐(10)供液的第二开关阀(122)、控制各中压区储罐(10)内工作气压的中压补气阀(151)、及控制低压区缓冲罐(18)内工作气压的低压补气阀(152)；
    气压检测单元，包括设置在各中压区储罐(10)及低压区缓冲罐(18)内的气压检测计，气压检测计实时检测各中压区储罐(10)及低压区缓冲罐(18)内的工作气压值；
    处理单元，包括控制各第一开关阀(121)、第二开关阀(122)、中压补气阀(151)及低压补气阀(152)开关动作的PLC控制器；
    气压检测单元将每个中压区储罐(10)内的工作气压值及低压区缓冲罐(18)内的工作气压值发送至处理单元；
    处理单元通过控制第一开关阀(121)选择一个中压区储罐(10)与低压区缓冲罐(18)导通，处理单元通过选中的中压区储罐(10)的中压补气阀(151)控制该中压区储罐(10)的工作气压P1始终大于低压区储罐的工作气压P2。
  7. 根据权利要求6所述的浮式液化天然气存储和气化装置的控制系统，其特征在于：处理单元控制中压区储罐(10)内的工作气压P1保持在工作气压范围 之内：Pa<P1<Pb；
    Pa为中压区储罐(10)的工作气压下限，P1低于Pa时，中压补气阀(151)打开，补气管(16)向中压区储罐(10)内补入气体；
    Pb为中压区储罐(10)的工作气压上限，P1高于Pb时，中压补气阀(151)关闭，补气管(16)停止补气。
  8. 根据权利要求6所述的浮式液化天然气存储和气化装置的控制系统，其特征在于：低压区缓冲罐(18)的工作气压P2保持在工作气压范围之内：Pc<P2<Pd；
    Pc为低压区缓冲罐(18)的工作气压下限，P2低于Pc时，低压补气阀(152)打开，补气管(16)向低压区缓冲罐(18)内补入气体；
    Pd为低压区缓冲罐(18)的工作气压上限，P2高于Pd时，低压补气阀(152)关闭，补气管(16)停止补气。
  9. 根据权利要求6所述的浮式液化天然气存储和气化装置的控制系统，其特征在于：中压补气阀(151)和低压补气阀(152)为气动开关阀；
    第一开关阀(121)、第二开关阀(122)、中压补气阀(151)及低压补气阀(152)均为常闭开关阀。
  10. 根据权利要求6所述的浮式液化天然气存储和气化装置的控制系统，其特征在于：处理单元还包括无线通信模块，处理单元通过无线通信模块与远程服务器连接，远程服务器与智能终端连接，智能终端通过远程服务器、无线通信模块获取处理单元中的数据，智能终端通过远程服务器、无线通信模块、处理单元控制开关控制单元的开关动作。
  11. 浮式液化天然气存储和气化装置的控制方法，其特征在于：包括如下步骤：
    S1，LNG运输船与船体(23)的总进液口(17)连接，船体(23)的高压天然气出口(22)与用气设备连接，处理单元依次打开第二开关阀(122)向各中压区储罐(10)内输入LNG，中压区储罐(10)的工作气压P1范围为：Pa-Pb，低压区缓冲罐(18)的工作气压P2范围为：Pc-Pd，其中，Pb>Pa>Pd>Pc；
    S2，处理单元通过控制各第一开关阀(121)开关动作选择一个中压区储罐(10)作为工作储罐，LNG在工作气压差的作用下自工作储罐流入低压区缓冲罐(18)；
    S3，通过通气管路(24)使低压区缓冲罐(18)的工作气压与潜液泵箱(20)的工作气压始终相同，流入低压区缓冲罐(18)的LNG连续流入潜液泵箱(20)；
    S4，潜液泵(19)将潜液泵箱(20)内的LNG持续输送至LNG气化装置(21)内；
    S5，LNG气化装置(21)持续向用气设备提供高压气态天然气；
    S6，工作储罐的工作气压P1低于Pa时，中压补气阀(151)打开，补气管(16)向中压区储罐(10)内补气，当中压区储罐(10)的工作气压P1高于Pb时，中压补气阀(151)关闭，补气管(16)停止补气；
    低压区缓冲罐(18)的工作气压P2低于Pc时，低压补气阀(152)打开，补气管(16)向低压区缓冲罐(18)内补气，当低压区缓冲罐(18)的工作气压P2高于Pd时，低压补气阀(152)关闭，补气管(16)停止补气。
  12. 根据权利要求10所述的浮式液化天然气存储和气化装置的控制方法，其特征在于，还包括步骤：
    S7，处理单元关闭工作储罐的第一开关阀(121)，处理单元通过控制各第一开关阀(121)的开关动作选择另一个中压区储罐(10)作为新工作储罐。
  13. 根据权利要求10所述的浮式液化天然气存储和气化装置的控制方法，其特征在于：处理单元选择工作储罐的方式为：打开目标中压区储罐(10)的第一开关阀(121)并关闭其余中压区储罐(10)的第一开关阀(121)。
PCT/CN2018/114233 2017-09-26 2018-11-07 浮式液化天然气存储和气化装置、控制系统及控制方法 WO2019063025A1 (zh)

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