CN116293414A - System and method for rapidly recovering BOG gas in LNG tank car - Google Patents

System and method for rapidly recovering BOG gas in LNG tank car Download PDF

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Publication number
CN116293414A
CN116293414A CN202310083885.5A CN202310083885A CN116293414A CN 116293414 A CN116293414 A CN 116293414A CN 202310083885 A CN202310083885 A CN 202310083885A CN 116293414 A CN116293414 A CN 116293414A
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Prior art keywords
lng
gas
bog
pressure
compressor
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Inventor
刘鹏
牛卓韬
鹿洋
刘玉丰
伊晓冬
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Xindi Energy Engineering Technology Co Ltd
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Xindi Energy Engineering Technology Co Ltd
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Priority to CN202310083885.5A priority Critical patent/CN116293414A/en
Publication of CN116293414A publication Critical patent/CN116293414A/en
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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
    • F17C5/00—Methods or apparatus for filling containers with liquefied, solidified, or compressed gases under pressures
    • F17C5/06—Methods or apparatus for filling containers with liquefied, solidified, or compressed gases under pressures for filling with compressed gases
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
    • F16L59/00—Thermal insulation in general
    • F16L59/02—Shape or form of insulating materials, with or without coverings integral with the insulating materials
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
    • F16L9/00—Rigid pipes
    • F16L9/02—Rigid pipes of metal
    • 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
    • F17C13/004—Details of vessels or of the filling or discharging of vessels for large storage vessels not 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
    • 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
    • F17C13/02—Special adaptations of indicating, measuring, or monitoring equipment
    • F17C13/026—Special adaptations of indicating, measuring, or monitoring equipment having the temperature 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
    • F17C9/00—Methods or apparatus for discharging liquefied or solidified gases from vessels not 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
    • F17C2205/00—Vessel construction, in particular mounting arrangements, attachments or identifications means
    • F17C2205/01—Mounting arrangements
    • F17C2205/0123—Mounting arrangements characterised by number of vessels
    • F17C2205/013—Two or more vessels
    • 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
    • F17C2205/0352—Pipes
    • 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
    • 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
    • F17C2227/0157—Compressors
    • F17C2227/0164—Compressors with specified compressor 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
    • F17C2227/03—Heat exchange with the fluid
    • F17C2227/0302—Heat exchange with the fluid by heating
    • 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
    • F17C2250/01—Intermediate tanks
    • 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
    • F17C2250/032—Control means using computers
    • 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
    • F17C2250/036—Control means using alarms
    • 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
    • F17C2250/07—Actions triggered by measured parameters
    • F17C2250/072—Action when predefined value is reached
    • 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
    • F17C2265/00—Effects achieved by gas storage or gas handling
    • F17C2265/03—Treating the boil-off
    • F17C2265/032—Treating the boil-off by recovery
    • F17C2265/036—Treating the boil-off by recovery with heating
    • 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
    • F17C2265/00—Effects achieved by gas storage or gas handling
    • F17C2265/03—Treating the boil-off
    • F17C2265/032—Treating the boil-off by recovery
    • F17C2265/037—Treating the boil-off by recovery with pressurising
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/30—Use of alternative fuels, e.g. biofuels

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Filling Or Discharging Of Gas Storage Vessels (AREA)

Abstract

The invention provides a system and a method for rapidly recycling BOG gas in an LNG tank car, wherein the system comprises an LNG loading/unloading sledge body, a BOG heater, an LNG bimetal full-containing storage tank, a compressor in a CNG filling station, an inlet buffer tank, an outlet buffer tank, a CNG gas storage cylinder group, a CNG car filling machine and related natural gas pipelines. The natural gas compressor in the CNG gas station adjacent to the liquefied natural gas storage and distribution gasification station is adopted to recycle BOG gas in the LNG tank car generated in the LNG loading and unloading process, and the LNG tank car is communicatedAnd (5) pressurizing by a compressor, and storing the compressed gas in a CNG gas storage cylinder group or filling the CNG automobile with gas. The invention can shorten the time of LNG in the loading/unloading process, reasonably recover BOG gas generated in the LNG loading/unloading process, improve the utilization rate of natural gas and reduce the greenhouse gas CH 4 Is arranged in the air.

Description

System and method for rapidly recovering BOG gas in LNG tank car
Technical Field
The invention relates to a system and a method for rapidly recovering BOG gas in an LNG tank car, in particular to a system and a method for rapidly recovering BOG gas in a liquefied natural gas storage and distribution gasification station by utilizing a CNG gas station.
Background
Natural gas is a high-quality, efficient, clean and convenient energy source. The method has the advantages of promoting the natural gas utilization engineering, improving the proportion of natural gas resources in energy consumption, optimizing the energy structure, improving the life quality of people and protecting the environment, and has great significance in the aspects of promoting the modern construction of cities, adjusting the industrial structure, developing economy and the like. The gas supply enterprises need to establish natural gas reserves to make the gas emergency reserves system sound. 5000m was adopted in large batches for construction of various places since 2018 3 ～50000m 3 LNG storage and gasification station of LNG normal-pressure full-containment storage tank.
Due to the reasons of heat leakage and the like of an LNG tank truck, an LNG storage tank and a pipeline system in the LNG storage and distribution substation, BOG gas is inevitably generated in the LNG storage and distribution substation, so that the pressure in the LNG tank truck or the LNG storage tank is continuously increased by the BOG gas, and the LNG tank truck is not beneficial to storage and transportation.
In the unloading process of a large LNG storage gasification station, the condition that a plurality of LNG tank cars are unloaded simultaneously frequently occurs, after the LNG tank cars are unloaded completely, BOG gas in the LNG tank cars needs to be recovered, the time for the LNG tank cars to stay in the station is prolonged due to the recovered BOG gas, the working time of operators is correspondingly prolonged, the natural gas pressure in the tank cars is generally between 0.55 and 0.65MPa after the LNG tank cars are unloaded, and when the tank cars are filled in an upstream LNG liquefaction factory or an LNG receiving station, the natural gas pressure in the tank cars is generally required to be lower than 0.2MPa, the storage capacity of the LNG tank cars is about 50 cubic meters, and the BOG gas is 300-400 kg. The direct air defense of the gas can pollute the atmosphere, waste natural gas resources, and re-liquefaction treatment is needed when the gas returns to an upstream LNG liquefaction plant or an LNG receiving station.
The BOG recovery treatment process in the LNG storage and distribution gasification station needs to select a reasonable scheme according to the downstream gas pipe network condition, the whole-field thermodynamic balance and other factors, so that the comprehensive cost of site construction and operation is reduced. The current BOG recovery treatment process mainly adopts the following 3 types:
1) Heating, pressurizing by a BOG compressor, and then conveying the mixture into a natural gas pipeline network;
2) Heating and then using the heated gas as fuel gas for equipment such as an in-situ hot water boiler, a heat conduction oil furnace and the like;
3) As fuel gas + re-liquefaction in the plant.
Because the BOG is closely related to the storage temperature in the LNG tank wagon, the change of the loading load of the LNG, the running condition of the production process, the external climate condition and the like, the generated quantity has larger fluctuation, and when the BOG is gasified and externally transported or used as fuel gas in a factory, the BOG is limited by the gas consumption of downstream gas and the gas use non-uniformity, and a peak regulation gas storage facility is required to be arranged; when re-liquefaction is adopted, the operation flexibility of re-liquefaction equipment is required to be higher, and the investment cost is increased.
Disclosure of Invention
The invention aims to solve the technical problems, and provides a system for rapidly recovering BOG gas in an LNG tank car, which has the dual functions of shortening the time of the LNG tank car and reasonably recovering the BOG gas, reduces the evaporated gas of natural gas of an LNG product in the process of transporting and loading and unloading the LNG tank car, shortens the loading and unloading time of the LNG tank car in a station, and improves the efficiency of LNG storage and filling.
The invention relates to a system for quickly recycling BOG gas in an LNG tank car, which comprises one or more LNG loading/unloading sleds, an LNG double-metal full-containing storage tank, a BOG heater, an inlet buffer tank, a compressor in a CNG filling station, an outlet buffer tank, a CNG gas storage cylinder group and a CNG car filling machine, wherein the one or more LNG loading/unloading sleds are connected with the LNG double-metal full-containing storage tank through LNG liquid phase pipelines, the one or more LNG loading/unloading sleds are additionally provided with natural gas low-temperature branch pipelines and the LNG double-metal full-containing storage tank are provided with gas-phase space BOG gas pipelines, a BOG gas phase main pipe is summarized to be connected to an inlet of the BOG heater, an outlet pipeline of the BOG heater is sequentially connected with the inlet buffer tank, the compressor in the CNG filling station, the outlet buffer tank, the outlet pipeline of the CNG buffer tank is divided into two paths, one path is connected with the CNG car filling machine, and the other path is connected with the CNG gas storage cylinder group.
The natural gas pipeline can be connected with a plurality of LNG tank cars in series and used for introducing and recycling BOG gas of the LNG tank cars, the LNG tank car can further comprise a PLC control unit, a pressure detection instrument which is used for detecting BOG pressure in the LNG tank cars and is arranged on a natural gas low-temperature branch pipeline led out from the LNG loading/unloading skid body, a temperature detection instrument which is used for detecting BOG gas temperature on a pipeline which enters a compressor after the BOG heater, the LNG tank car BOG pressure detection instrument and the temperature detection instrument after the BOG heater are connected with a control unit, and a PLC control unit which controls the start and stop of the natural gas compressor, for example, when the pressure detection instrument detects pressure to be lower than 0.15MPa or the temperature detection instrument detects temperature to be lower than-20 ℃, the control compressor is stopped in a linkage mode, and the BOG compressor exhaust capacity is controlled according to the pressure interlocking of the LNG tank cars, so that the pressure range (0.1-0.6 MPa) of the LNG tank car storage tank is ensured. The pressures described herein are all gauge pressures.
Further, the natural gas low-temperature pipeline for conveying the BOG in the LNG tank wagon to the inlet of the BOG heater through the LNG loading/unloading pry is made of stainless steel, double-brand stainless steel is preferred, and when the cold insulation material is adopted for cold insulation, the thickness of the cold insulation layer is more than or equal to 100mm.
Further, the compressor in the CNG filling station is a piston type normal-temperature natural gas compressor, a BOG heater is arranged in front of the compressor, preferably an aluminum fin-tube type gasifier is used for heating low-temperature BOG gas (-140 ℃ to-160 ℃) in the LNG tank car to above-20 ℃.
Further, a pressure detection instrument and a transmitter are arranged on an outlet pipeline of the natural gas compressor and are connected with a central control room PLC control unit, a pressure alarm linkage is arranged on the outlet pipeline of the natural gas compressor, for example, sound and light alarm is carried out when the pressure exceeds 24.5MPa, and the compressor system is stopped in a linkage manner when the pressure exceeds a set value such as 25 MPa.
Further, the CNG storage facility adopts a high-pressure gas storage cylinder group, the design pressure of the cylinder group is 27.5MPa, a pressure detection instrument and a transmitter are arranged on the high-pressure gas storage cylinder group, and after the pressure high-pressure alarm (for example, more than 25 MPa) is monitored, the CNG storage facility is transmitted to a PLC control system through an instrument cable, and a compressor in a CNG filling station is stopped in a linkage mode.
Another aspect of the present invention is to provide a method for achieving rapid unloading by recovering BOG gas, the method comprising:
after the LNG tank wagon enters a station, the pressure in the common tank wagon is about 0.1-0.3 MPa, and the pressure in the LNG tank wagon is increased to 0.55-0.6 MPa through the unloading booster or the normal-temperature natural gas supplementing, so that the unloading speed of the LNG tank wagon is ensured; when the LNG tank wagon is unloaded and then the pressure in the LNG tank wagon is higher, a large amount of low-temperature BOG gas is accumulated, the pressure in the tank wagon is monitored through an LNG tank wagon pressure detection instrument, a natural gas compressor is started, the BOG gas in the tank wagon is heated through a BOG heater, the compressed gas enters a CNG gas storage cylinder group for storage or enters a CNG automobile for filling after being lifted by the compressor, when the pressure of the natural gas in the tank wagon is reduced to the lower limit value of an inlet of the compressor, such as 0.15MPa, low-pressure alarm is carried out, the compressor is closed through linkage control, the pressure of the natural gas in the LNG tank wagon can be rapidly reduced, the time is saved by about 20-60 minutes compared with the time that the natural gas in the LNG tank wagon enters the downstream medium-pressure (design pressure of 0.4 MPa) through the BOG heater, the unloading operation time of the LNG tank wagon is shortened, the workload of operation staff is reduced, and the efficiency is improved.
In the method, a pressure detection instrument and a transmitter arranged on an outlet pipeline of the natural gas compressor upload an audible and visual alarm when the pressure of the PLC control system in the central control room exceeds 24.5MPa, and the compressor system is stopped in a linkage manner when the pressure exceeds a set value such as 25 MPa.
In the method, after the pressure detection instrument and the transmitter arranged on the high-pressure gas storage cylinder group monitor that the pressure high pressure exceeds 25MPa and alarm, the pressure detection instrument and the transmitter are transmitted to the PLC control system through an instrument cable, and the natural gas compressor is stopped in a linkage way.
Furthermore, except that a part of the BOG gas is recycled by a BOG compressor to carry out CNG automobile gas filling, the other part of the BOG gas is heated by a BOG heater to become normal-temperature natural gas, the normal-temperature natural gas is used as fuel gas in a station or enters an LNG tank car after being pressurized, the reasonable pressure difference between the LNG tank car and an LNG normal-pressure storage tank is maintained by lifting the pressure in the LNG tank car entering the station, the purpose of lifting the LNG unloading speed is achieved, and the proportion of the other part of the BOG gas can be determined according to the actual running load, for example, the LNG unloading speed is 10-30 vol%.
The invention has the beneficial effects that:
(1) The system and the control scheme have higher degree of automation and better applicability, can realize that a plurality of LNG tank cars in the peak shaving station are unloaded simultaneously and rapidly, shorten the time for recovering the BOG of the LNG tank cars, reduce the on-site operation time of operators and improve the storage efficiency of the LNG normal pressure storage tank.
(2) The overpressure emission or direct emission of dangerous gases such as BOG and the like in the transportation process of the LNG tank car is reduced, and the utilization rate of natural gas resources is improved. The proposal of the scheme has important significance for improving the safety and reliability of LNG tank wagon transportation, reducing the running cost of the natural gas station, saving energy and reducing emission.
Drawings
FIG. 1 is a system for recovering BOG gas in a liquefied natural gas storage and distribution station using a CNG gas station according to the present invention.
Detailed Description
Further description is provided below in connection with fig. 1 and the examples.
As shown in fig. 1, a system for rapidly recovering BOG gas in a liquefied natural gas storage and distribution gasification station by using a CNG gas station comprises one or more LNG loading/unloading sleds (for example, a first LNG loading/unloading sleds 1-1, a second LNG loading/unloading sleds 1-2, a third LNG loading/unloading sleds 1-3, a plurality of LNG loading/unloading sleds adopting a parallel connection mode), an LNG bimetal full-containment storage tank 2, a BOG heater 3, an inlet buffer tank 4, compressors 5-1 and 5-2 in the CNG gas station, an outlet buffer tank 6, a CNG car gas dispenser 7 and a CNG gas storage bottle group 8.
The one or more LNG loading/unloading sleds are connected to the LNG bimetal total-containing storage tank 2 through LNG liquid phase pipelines (for example, after the first LNG liquid phase branch pipelines L1, the second LNG liquid phase branch pipelines L2 and the third LNG liquid phase branch pipelines L3 are converged to form an LNG liquid phase main pipe L4), the one or more LNG loading/unloading sleds are additionally provided with natural gas low-temperature branch pipelines (for example, the first BOG branch pipelines L5, the third BOG branch pipelines L6, the L7 and the like) and the LNG bimetal total-containing storage tank 2 are provided with gas phase space BOG gas pipelines, the BOG gas phase main pipe L8 is integrated to be connected to the inlet of the BOG heater 3, the outlet pipelines of the BOG heater 3 are sequentially connected with the inlet buffer tank 4, the compressors (for example, the compressors 5-1 and 5-2 in the first and the second gas filling stations in parallel connection) and the outlet buffer tank 6, the outlet pipelines of the outlet buffer tank 6 are divided into two paths, one path is connected with the CNG automobile gas filling machine 7, and the other path is connected with the CNG gas storage cylinder group 8.
The buffer tanks are arranged in front and behind the compressor according to the standard requirements, the speed of natural gas entering the buffer tanks is reduced, and the pressure can be stabilized, so that the vibration of the compressor is lightened, the power consumption is reduced, and the looseness of the connecting part is prevented.
The system comprises a natural gas pipeline, a pressure detection instrument P1, a pressure detection instrument P2, a pressure detection instrument P3 (respectively arranged on first to third natural gas low-temperature branch pipelines L1, L2 and L3 led out from an LNG loading/unloading skid 1), a temperature detection instrument T1 (arranged on a connecting pipeline between the BOG heater and the compressor) for detecting the temperature of BOG gas on a pipeline which enters the compressor after the BOG heater, and a PLC control system for controlling the start and stop of the natural gas compressor, wherein the natural gas pipeline can be connected with a plurality of LNG tank cars in series for introducing and recovering BOG gas of the LNG tank cars, and the LNG tank cars, the BOG pressure detection instrument P1 and the BOG heater are connected with a control unit; and when the P1 detection pressure is lower than 0.15MPa or the T1 detection temperature is lower than-20 ℃, the compressor is controlled to stop in a linkage manner.
The BOG in the LNG tank car is connected to the inlet of the BOG heater 3 via an LNG loading/unloading skid via a natural gas cryogenic pipeline.
The BOG heater 3 is preferably an aluminum fin-tube heat exchanger and heats the low-temperature BOG gas (-140 ℃ to-160 ℃) in the LNG tank car to more than-20 ℃.
The system is characterized in that a pressure detection instrument and a transmitter P4 are arranged on an outlet pipeline of a natural gas compressor through a PLC control unit, a pressure alarm linkage (pressure alarm device) is arranged on the outlet pipeline of the natural gas compressor, audible and visual alarm is carried out when the pressure exceeds 24.5MPa, and the compressor system is stopped in a linkage manner when the pressure exceeds a set value such as 25 MPa.
The CNG storage facility adopts a high-pressure gas storage cylinder set, the design pressure is 27.5MPa, a pressure detection instrument and a transmitter P5 are arranged on the high-pressure gas storage cylinder set, when the pressure is monitored to be higher than 25MPa and the alarm is given out, the pressure is transmitted to a PLC control system through an instrument cable, and a natural gas compressor is stopped in a linkage way.
Another aspect of the present invention is to provide a method for achieving rapid unloading by recovering BOG gas, the method comprising:
after the LNG tank wagon enters a station, the pressure in the common tank wagon is about 0.1-0.3 MPa, the pressure in the LNG tank wagon is required to be increased to 0.55-0.6 MPa through a unloading booster or normal-temperature natural gas, the unloading speed of the LNG tank wagon is ensured, LNG liquid in the LNG tank wagon is unloaded to the LNG bimetal full-containment storage tank 2 through an LNG liquid phase main pipe L4, and after the unloading is finished, the liquid inlet valves of the LNG loading/unloading pry (1-3) and the LNG bimetal full-containment storage tank 2 are closed. When the LNG tank wagon is unloaded, the pressure in the LNG tank wagon is higher, a large amount of low-temperature BOG gas is accumulated, the pressure in the tank wagon is monitored through an LNG tank wagon pressure detection instrument, a natural gas compressor is started, the BOG gas (generally-140 ℃ to-160 ℃) in the tank wagon is heated to be higher than-20 ℃ through a BOG heater, the compressed gas is lifted to 22-25 MPa and then enters a CNG gas storage cylinder group to be stored or enters a CNG automobile to be filled, when the pressure (P1 value) of the natural gas in the tank wagon is reduced to the lower limit value of an inlet of the compressor, such as 0.15MPa, low-pressure alarm is carried out, the compressor is closed through linkage control, the pressure of the natural gas in the LNG tank wagon can be rapidly reduced, the time is saved by about 20-60 minutes compared with the time that the natural gas pipe network of the natural gas in the downstream medium pressure (0.4 MPa) of the design pressure of the conventional LNG tank wagon through the BOG heater, the unloading operation time of the LNG tank wagon is shortened, the workload of operators is reduced, and the efficiency is remarkably improved.
In the method, a pressure detection instrument and a transmitter P4 arranged on an outlet pipeline of the natural gas compressor upload the pressure of the central control indoor PLC control system to carry out audible and visual alarm when the pressure exceeds 24.5MPa, and the compressor system is stopped in a linkage manner when the pressure exceeds a set value such as 25 MPa.
In the method, after the pressure detection instrument and the transmitter arranged on the high-pressure gas storage cylinder group monitor that the pressure high pressure exceeds 25MPa and alarm, the pressure detection instrument and the transmitter are transmitted to the PLC control system through an instrument cable, and the natural gas compressor is stopped in a linkage way.
In the project, except for the fact that part of BOG gas is recycled through a BOG compressor to carry out CNG automobile gas filling, the other part of the BOG gas is heated through a BOG heater to become normal-temperature natural gas, the normal-temperature natural gas is used as fuel gas in a station or is pressurized to enter an LNG tank car, the reasonable pressure difference between the LNG tank car and an LNG normal-pressure storage tank is maintained by lifting the pressure of the LNG tank car entering the station, the purpose of lifting LNG unloading speed is achieved, the proportion of the other part of the BOG gas can be determined according to actual running load, for example, the proportion of the BOG gas occupies 10-30% by volume.
It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. And obvious variations or modifications thereof are contemplated as falling within the scope of the present invention.

Claims (10)

1. A system for rapidly recovering BOG gas in LNG tank cars is characterized by comprising one or more LNG loading/unloading sleds, an LNG bimetal full-containment storage tank, a BOG heater, an inlet buffer tank, a compressor in a CNG filling station, an outlet buffer tank, a CNG storage cylinder group and a CNG car filling machine,
the LNG loading/unloading skid bodies are connected to the LNG bimetal full-containing storage tank through LNG liquid phase pipelines, the one or more LNG loading/unloading skid bodies are additionally provided with natural gas low-temperature branch pipelines and the LNG bimetal full-containing storage tank is provided with gas-phase space BOG gas pipelines, a BOG gas-phase main pipe is collected to be connected to an inlet of a BOG heater, an outlet pipeline of the BOG heater is sequentially connected with an inlet buffer tank, a compressor and an outlet buffer tank in a CNG filling station, the outlet pipeline of the outlet buffer tank is divided into two paths, one path is connected with a CNG automobile filling machine, and the other path is connected with a CNG storage cylinder group.
2. The system of claim 1, further comprising a PLC control unit, a pressure detector disposed on a low temperature natural gas branch line leading from the LNG loading/unloading skid for detecting the BOG pressure in the LNG tank, a temperature detector for detecting the BOG gas temperature on the line entering the compressor after the BOG heater, wherein the LNG tank BOG pressure detector and the BOG heater rear temperature detector are connected to the PLC control unit for controlling the start and stop of the natural gas compressor.
3. The system of claim 1, wherein the natural gas cryogenic pipeline that delivers BOG in LNG tankers to the BOG heater inlet through LNG loading/unloading skids is made of stainless steel, and the thickness of the cold insulation layer is greater than or equal to 100mm when cold insulation material is used for cold insulation.
4. The system of claim 1, wherein the compressor in the CNG fueling station is a piston normal temperature natural gas compressor, and the BOG heater is provided before the compressor, and is an aluminum fin tube gasifier.
5. The system of claim 1 or 4, wherein the BOG heater heats the low temperature BOG gas in the LNG tank car to above-20 ℃ from-140 ℃ to-160 ℃.
6. The system of any one of claims 1-4, wherein a pressure detection instrument and a transmitter are arranged on an outlet pipeline of the natural gas compressor and connected with a central control room PLC control unit, and a pressure alarm linkage is arranged on the outlet pipeline of the natural gas compressor.
7. The system of claim 1, wherein the CNG storage facility employs a high pressure gas cylinder set with a design pressure of 27.5MPa, the high pressure gas cylinder set is provided with a pressure detection instrument and a transmitter, and when the pressure high pressure alarm is monitored, the pressure high pressure alarm is transmitted to the PLC control system through an instrument cable, and the compressor is stopped in a chain manner.
8. A method of rapidly recovering BOG gas in an LNG tanker, the method comprising:
after the LNG tank wagon enters the station, the pressure in the LNG tank wagon is raised to 0 55-0.6 MPa through a unloading booster or normal-temperature natural gas supplementing, so that the unloading speed of the LNG tank wagon is ensured; when the LNG tank wagon is unloaded and then the pressure in the LNG tank wagon is higher, a large amount of low-temperature BOG gas is gathered, the pressure in the tank wagon is monitored through an LNG tank wagon pressure detection instrument, a natural gas compressor is started, the BOG gas in the tank wagon is heated through a BOG heater and is pumped by the compressor, then the BOG gas enters a CNG gas storage cylinder group for storage or enters a CNG automobile for filling, when the pressure of the natural gas in the tank wagon is reduced to the lower limit value (for example, 0.15 MPa) of the inlet of the compressor, low-pressure alarm is carried out, and the compressor is closed through linkage control.
9. The method of claim 8, wherein the pressure detection instrument and the transmitter arranged on the outlet pipeline of the natural gas compressor upload the sound and light alarm when the pressure of the central control indoor PLC control system exceeds 24.5MPa, and the compressor system is stopped in a linkage way when the pressure exceeds a set value of 25 MPa; and/or
The BOG heater heats the low-temperature BOG gas in the LNG tank car to above minus 20 ℃ at minus 140 ℃ to minus 160 ℃.
10. The method according to claim 8 or 9, wherein a pressure detection instrument and a transmitter arranged on the high-pressure gas storage cylinder group transmit an alarm to the PLC control system through an instrument cable after detecting that the pressure is higher than 25MPa, and the natural gas compressor is stopped in a linkage way.
CN202310083885.5A 2023-02-09 2023-02-09 System and method for rapidly recovering BOG gas in LNG tank car Pending CN116293414A (en)

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CN202310083885.5A CN116293414A (en) 2023-02-09 2023-02-09 System and method for rapidly recovering BOG gas in LNG tank car

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Application Number Priority Date Filing Date Title
CN202310083885.5A CN116293414A (en) 2023-02-09 2023-02-09 System and method for rapidly recovering BOG gas in LNG tank car

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