63 results about "Bog" patented technology

The invention discloses an LNG storage tank BOG liquefaction recovery system and a control method thereof.The system comprises an LNG storage tank, an LNG buffer tank, an LNG pump and a refrigerating machine, the LNG pump is installed in the LNG buffer tank, when BOG in the LNG storage tank needs to be recovered, BOG conveyed by the LNG storage tank is cooled and liquefied through the refrigerating machine and then returns to the LNG storage tank, recovery of BOG gas in the LNG storage tank is achieved, and in the BOG recovery process, the BOG is recovered through the refrigerating machine. And when the supercooling degree of the LNG storage tank needs to be maintained, the LNG conveyed by the LNG storage tank is cooled through the refrigerating machine, the cooled LNG returns into the LNG storage tank, and after the cooled LNG is mixed with the LNG in the LNG storage tank, the temperature of the LNG in the LNG storage tank is reduced, so that the supercooling degree of the LNG storage tank is maintained. The whole system is simple in structure, BOG in the LNG storage tank can be liquefied and recycled, and the supercooling degree of the LNG storage tank can be maintained.

The invention discloses a fuel gas supply and carbon capture system, which covers the whole process flows of fuel gas supply, CO2 capture, CO2 compression, CO2 liquefaction, CO2 storage and the like, and fully utilizes the cold energy of BOG (Boil Off Gas) from an LNG (Liquefied Natural Gas) cabin for cooling the BOG compressed by a BOG compressor, so that an additional intercooler, an aftercooler and a fresh water cooling system are not needed; the heat energy of the compressed BOG and the compressed CO2 is fully utilized to heat the BOG from the LNG cabin, so that the temperature of the BOG entering the BOG compressor meets the air inlet temperature requirement of a normal-temperature compressor, and therefore, the BOG compressor can adopt the normal-temperature compressor; heat energy of waste gas of the dual-fuel engine is fully utilized to heat rich liquid, so that additional heating media and heat sources are not needed; the cold energy of BOG from the LNG cabin is fully utilized and used for liquefying CO2, and therefore extra cooling media and cold sources are not needed.

Carbon dioxide re-liquefaction may be provided by a system capable of receiving a vented boiled off gas stream from a storage vessel at a first compressor; compressing the vented BOG stream at the first compressor into a first compressed BOG stream at a first pressure and a second compressed BOG stream at a second pressure, greater than the first pressure; cooling the first compressed BOG stream in a heat exchanger to produce a liquid stream by: cooling, via a refrigerant unit, the second compressed BOG stream to produce a first cold stream, of a temperature less than that of the first compressed BOG stream; exchanging heat from the first compressed BOG stream against tire first cold stream; and returning the liquid stream to the storage vessel.

A gas supply and carbon capture system, comprising an LNG tank, a BOG compressor set, a dual-fuel engine, a CO2 capture unit, a CO2 compressor, a heat exchanger, and a CO2 storage tank, wherein the LNG tank is used for storing liquid LNG, BOG formed at the inner top of the LNG tank is fed to a cold side of the heat exchanger; the heat exchanger is used for heat exchange between pressurized CO2 and the BOG, cold energy of the BOG is utilized to liquefy the CO2, the obtained liquid CO2 is stored in the CO2 storage tank, and the BOG having a higher temperature after the heat exchange is sent to the BOG compressor set; and the BOG compressor set is used for pressurizing the BOG having a higher temperature and then delivering the BOG to the dual-fuel engine for combustion, and the BOG compressor set employs normal-temperature compressors. By means of the system, the cold energy of the BOG from the LNG tank is fully utilized, and the temperatures of the BOG entering the BOG compressors are caused to meet an inlet temperature requirement of the normal-temperature compressors.

The present invention relates to a special sampling device for soil in a peat swamp wetland, comprising a base plate, a slide plate symmetrically arranged on the bottom of the base plate, an arc-shaped pressure plate arranged on the rear side of the bottom of the base plate through a bracket, a push handle arranged on the front side of the top of the base plate, a drilling mechanism arranged on a fixed plate and the center of the base plate, a sampling mechanism arranged in the drilling mechanism, and a cleaning mechanism arranged in the sampling mechanism; the present invention can solve the following existing problems: the present invention separates and collects soil and moisture in a storage cylinder and a storage cover through the cooperation of a moving tube and a hollow round cake, and then cleans the storage cylinder and the storage cover with the collected water after the sampling is completed, thereby preventing residual soil from contaminating the sample; the present invention realizes sampling of soil at different depths in a peat swamp through the cooperation of an arc groove and an arc-shaped sampling plate, thereby reducing the labor intensity of staff; and also prevents soil from entering the cylinder and contaminating the inner wall of the cylinder through the cooperation of a strip block and a mud guard.

The application provides a method for rapidly distinguishing coal rock sedimentary environment by using ash yield and total sulfur content, comprising the following steps: drawing an ash yield-total sulfur content relationship diagram of coal rock; obtaining ash yield data and total sulfur content data of a coal rock sample to be measured; and explaining the sedimentary environment of the coal rock sample to be measured according to the position area of the ash yield data and the total sulfur content data of the coal rock sample to be measured on the ash yield-total sulfur content relationship diagram. The application distinguishes the sedimentary environment of the coal rock sample to be measured according to the position area of the ash yield data and the total sulfur content data of the coal rock sample to be measured on the ash yield-total sulfur content relationship diagram. The distinguishing method of the application is simple in steps, can clearly and intuitively make an efficient judgment on whether the peat bog type in the coal rock sedimentary environment is affected by marine transgression, the test data is convenient to obtain, is not affected by subjective factors, and the distinguishing result is relatively accurate.

The present invention relates to the production of propagation plugs, primarily blocks of growth medium for the growing of cuttings and seed plants, and of the type consisting of a cylindrical block having an envelope of sheet material and an associated filling of sphagnum or a corresponding substrate material. The sheet material is here a netting or mesh, preferably biodegradable, having a mesh size within the range of 0.1 to 1.5 mm.

The utility model relates to the technical field of energy recovery, in particular to a BOG (boil-off gas) precooling liquefaction system for recovering LNG (liquefied natural gas) cold energy. According to the technical scheme, the system comprises an LNG storage tank and a first compressor connected with the LNG storage tank, and further comprises a refrigeration compression system and a BOG reliquefaction system which are connected with the LNG storage tank and the first compressor; wherein the refrigeration compression system comprises a first heat exchanger, a refrigeration compressor, an expansion valve and a second heat exchanger which are connected in sequence. According to the utility model, the LNG storage tank, the first compressor, the stop valve, the high-pressure pump, the refrigeration compression system, the BOG reliquefaction system and other structures are matched, and the refrigeration compression cycle process is adopted, so that the LNG cold energy which is gasified and output is transferred to BOG flowing out of the LNG storage tank, the cold energy required in the traditional BOG recondensation process is reduced, and the energy consumption is reduced. And the loss of the cold energy of the gasified and output LNG is also reduced, so that the cold energy of the LNG is fully recycled.

FIELD: agriculture.SUBSTANCE: used in growing plants in phytomodules, in “carpet” and container vegetal walls. The substrate for growing plants in vertical phytostructures includes expanded vermiculite, zeolite-containing tripoli from the Khotynetsky deposit, and deoxidized high-moor peat, in the stated quantitative ratio.EFFECT: production of light, nutritious, loose, breathable soil that retains moisture well, contains silicon necessary for plants in a form accessible to them, and has a high ion-exchange capacity.1 cl, 1 tbl, 2 ex

This application provides a method for improving the thermal efficiency of a BOG reliquefaction system, comprising: analyzing the interaction between energy loss and temperature difference values ​​using a support vector regression algorithm to obtain a balance model between energy loss and temperature difference; optimizing the heat transfer temperature difference control parameters using a gradient descent algorithm for the adjusted compression parameter set to obtain an optimized temperature difference control scheme; simulating the overall system efficiency under the interaction of equipment using the optimized temperature difference control scheme to determine whether the simulated efficiency meets a preset standard; if the simulated efficiency does not meet the preset standard, iteratively updating the parameters and adjusting the optimization path according to the energy loss reduction requirement to obtain an iteratively optimized path; applying the iteratively optimized path to the gas reliquefaction system in real time to determine whether the energy consumption cycle is broken, and obtaining the final system thermal efficiency index.

The application provides a method and system for controlling the generation of BOG boil-off gas, comprising the following steps: S1, analyzing and obtaining all influence parameters related to the generation of BOG boil-off gas; S2, screening all influence parameters by using a preset filter to obtain the influence parameters that can be calculated, adjusted and most economical; and S3, taking the screened influence parameters as adjustable parameters to suppress the generation of BOG boil-off gas. The application suppresses the generation of BOG boil-off gas, and reduces the generation of BOG boil-off gas from the source before the recovery of BOG boil-off gas.

The invention provides a CO2 transport ship BOG treatment system and method. The system comprises a CO2 liquid cargo tank, a stop valve, a compressor, a BOG heat exchanger, a check valve, a box type CO2 storage unit, a container and a CO2 steel cylinder. According to the system, BOG generated in the CO2 transportation process is stored in the box-type CO2 storage unit in a pressurization and reliquefaction mode. Compared with traditional low-temperature reliquefaction, a refrigerating system is not needed to cool BOG, power consumption is small, implementation is easy, and the CO2 transportation cost is greatly reduced. Meanwhile, according to the method, the ship is optimally provided with the number of the box-type CO2 storage units according to the length of the ship route and different seasons, resource waste caused by the fact that too many box-type CO2 storage units are arranged is avoided, and high flexibility and practicability are achieved.

The application provides a system for processing excess BOG of an LNG ship, and belongs to the technical field of ships.The system comprises a BOG supply system, an excess BOG utilization system, a flue gas energy storage system, a flue gas energy release system and an inerting system.Based on the complex sailing conditions of a ship, when the LNG ship sails at low load, sails in a maneuvering mode or is anchored, the excess BOG generated in the LNG liquid cargo tank is sent into a boiler for combustion, and then the energy of the excess BOG is converted into the pressure energy of flue gas and stored through a series of devices, so that the problem of waste of the BOG in the excess state is effectively solved; when the ship sails at high load or is unloaded at a discharge port, the energy of the flue gas is released, so that the energy of the BOG is reused.In addition, the stored flue gas can also be used for inerting of low-temperature pipelines and equipment at normal temperature or at a temperature of 0 DEG C to -60 DEG C, so that the inerting cost of the ship is reduced.

The present application relates to the technical field of image processing, in particular to a peat bog information extraction method and system based on GIS remote sensing image. The method collects multi-temporal optical remote sensing image, DEM data and pixel precipitation, pre-processes the multi-temporal optical remote sensing image, and performs semantic segmentation to identify the region of interest; the DEM data is analyzed for elevation characteristics to extract pixel slope and pixel convergence accumulation, the precipitation uniformity is calculated based on the pixel precipitation, and the pixel slope and pixel convergence accumulation are weighted and fused to screen the peat formation potential area; the coupling delay index is calculated based on the time delay of the vegetation green peak and the water supply trend peak value to screen the peat bog suspected area; the area threshold is screened to obtain the target peat bog area and output the result. The present application combines the differences between peat bog and ordinary bog in multi-dimensional characteristics, extracts patches with peat layer characteristics, and avoids misjudgment of peat bog relying on spectral feature recognition.

The present invention discloses a BOG heating circulation control system and method for a VLCC ship, including a BOG pre-heater, a normal-temperature BOG compressor, a control valve, and a BOG cooler; an output end of a first flow channel of the BOG pre-heater is respectively communicated with the control valve and the normal-temperature BOG compressor, and the control valve is communicated with a dual-fuel boiler. The normal-temperature BOG compressor is communicated with a low-pressure buffer tank through a first flow channel of the BOG cooler; a high-temperature ethylene glycol water circulation system is communicated with another flow channel of the BOG pre-heater to form a circulation loop, and heat exchange is performed between the high-temperature ethylene glycol water and the first flow channel of the BOG pre-heater; a low-temperature ethylene glycol water circulation system is respectively communicated with another flow channel of the BOG pre-heater and another flow channel of the BOG cooler to form a circulation loop, and heat exchange is respectively performed between the low-temperature ethylene glycol water and the first flow channel of the BOG pre-heater and the first flow channel of the BOG cooler. The present invention achieves the purpose of saving costs and energy.

The floating island structure comprises a bottom plate, mounting ends, mounting grooves and positioning ends, the mounting grooves are formed in the bottom plate, the mounting ends are slidably mounted in the mounting grooves, the positioning ends are symmetrically and fixedly mounted at the bottom end of the bottom plate, and a replacement device is fixedly mounted in the bottom plate. The replacing device comprises an extrusion groove, a moving groove, an extrusion plate, a pushing plate and a spring, the moving groove is symmetrically formed in the bottom plate, the extrusion plate is slidably mounted in the moving groove, the pushing plate is fixedly mounted at the top end of the extrusion plate, and the spring is arranged at the bottom end of the extrusion plate. When the equipment is used, multiple groups of floating islands can be quickly and stably combined and arranged, and subsequent single damaged and to-be-maintained floating islands can be quickly replaced efficiently under the condition that peripheral components are not influenced, so that the equipment is more stable and efficient when being used, and the service life of the equipment is prolonged.

A method of cooling and reliquefying a boil off gas (BOG) stream (901) from a liquefied carbon dioxide cargo stored in a tank or tanks (101) on a floating transportation vessel. The method comprises at least the following steps: • compressing the BOG stream (901) from the liquefied carbon dioxide cargo tank (101) in one or more stages of BOG compression (102, 103) to provide a compressed BOG discharge stream (906); • cooling the compressed BOG discharge stream (906) against a carbon dioxide refrigerant stream (918) to provide a cooled compressed BOG stream (907); and a warmer carbon dioxide refrigerant stream (911); • compressing the warmer carbon dioxide refrigerant stream (912) in one or more stages of refrigerant compression (106, 107) to provide a compressed carbon dioxide refrigerant discharge stream (916) for subsequent use as the carbon dioxide refrigerant stream (918), which is operable to cool and at least partially condense the compressed BOG discharge stream (907). The one or more stages of BOG compression (102, 103) and the one or more stages of refrigerant compression (106, 107) are provided by a single shaft multistage compression unit.

The invention relates to the technical field of energy conservation, in particular to a treatment system for recycling oil gas and BOG through BOG low-temperature cold energy cycle condensation. Emptying treatment of BOG and oil gas in an LNG oil gas combined building station can cause the problems of serious environmental pollution, environmental safety and resource waste. In order to solve the technical problems, the treatment system for recycling oil gas and BOG through BOG low-temperature cold energy cycle condensation of the LNG oil gas co-construction station is provided, on the basis of normal-temperature compression and normal-temperature water cooling, oil gas discharged in the operation process of the refueling part of the co-construction station is recycled only through low-temperature cold energy condensation of BOG discharged by an LNG storage tank; condensed exhaust gas meets the national environmental protection emission requirement, and the oil gas recovery rate reaches 99% or above, so that in the oil gas recovery process, a tail gas adsorption link does not need to be arranged, a refrigerating system does not need to be additionally arranged, and potential safety hazards and operation investment cost of oil gas recovery are greatly reduced.

The application discloses a BOG reliquefaction large refrigeration system based on reverse Brayton cycle and an operation method thereof. The system comprises a large reverse Brayton cycle refrigeration system and a BOG reliquefaction system. The large reverse Brayton cycle refrigeration system comprises an expander, a first motor, a first compressor, a bearing, a first heat exchanger, a second heat exchanger, a third heat exchanger, a fourth heat exchanger, a second compressor and a second motor. The BOG reliquefaction system comprises a liquefied natural gas storage device, a mechanical pump and a spray tower. The outlet of the liquefied natural gas storage device is connected with the mechanical pump and the second inlet of the fourth heat exchanger in sequence, the second outlet of the fourth heat exchanger is connected with the inlet of the spray tower, and the outlet of the spray tower is connected with the inlet of the liquefied natural gas storage device. The application avoids energy loss in the phase change process through the reverse Brayton cycle, and can reduce the overall operation cost compared with the traditional BOG treatment system.

The present invention discloses a method and related device for predicting the generation amount of liquefied BOG in an LNG storage tank based on heat exchange, belonging to the technical field of production prediction, including: obtaining the adiabatic performance parameters of the LNG storage tank, the thermophysical properties parameters of the LNG, and the structural parameters of the LNG storage tank; constructing a dynamic model of internal heat exchange in the LNG storage tank; obtaining the stratified temperature gradient of the liquid phase in the LNG storage tank and the stratified temperature gradient of the gas phase in the LNG storage tank, and obtaining the external surrounding environment parameters of the LNG storage tank; inputting the stratified temperature gradient of the liquid phase in the LNG storage tank, the stratified temperature gradient of the gas phase in the LNG storage tank, and the external surrounding environment parameters of the LNG storage tank into the dynamic model of internal heat exchange in the LNG storage tank, predicting the BOG generation rate of each height layer in the LNG storage tank, and calculating the total BOG generation amount of the LNG storage tank according to the BOG generation rate of each height layer in the LNG storage tank. This method and related device can accurately predict the BOG generation amount of the LNG storage tank.

The utility model discloses a bog reed rhizosphere soil collecting device, and belongs to the technical field of soil collection. The inner net basket is placed in the outer barrel, a gap is formed between the outer side wall of the inner net basket and the inner side wall of the outer barrel, and the outer side wall of the inner net basket is wrapped with a first gauze element; the center column is fixedly connected to the center of the interior of the inner net basket, a plurality of second gauze pieces are fixedly connected between the center column and the inner side wall of the inner net basket, and the inner space of the inner net basket is divided into a plurality of planting areas by the second gauze pieces. The single reed rhizosphere soil collecting device can collect rhizosphere soil of a single reed, facilitates statistics of various growth indexes of individuals, and improves the accuracy of test data.

The utility model relates to the technical field of biogas utilization, in particular to a livestock farm biogas and BOG comprehensive utilization mechanism which comprises a collecting cover installed at the top of a livestock farm biogas and BOG pool, a gas collecting treatment box is installed at the top of the collecting cover, the gas collecting treatment box is externally connected with a biogas compressor, and a drying device is installed in the gas collecting treatment box. The collecting cover is installed on the top of a biogas and BOG pool of a livestock farm, a mixture of biogas and BOG can be effectively collected, the collecting efficiency of the gas is ensured, leakage is reduced, potential influences on the environment are reduced, the arranged gas collecting treatment box serves as a gas transfer station, a drying device is arranged in the gas collecting treatment box, and the drying effect is good. And the collected gas is subjected to necessary pretreatment before being used in the next step. Meanwhile, the gas conveying pipe at the top is connected with the biogas compressor, gas in the gas collection treatment box is compressed, the volume energy density of the gas is improved, and convenience is provided for subsequent storage or utilization.

The invention discloses a method for pre-cooling an LNG (Liquefied Natural Gas) loading pipeline by utilizing BOG (Boil Off Gas), belongs to the technical field of LNG, and aims to solve the problems of LNG loss, high cost, complicated operation, difficulty in thermal stress management and the like in the conventional pre-cooling method. According to the method, flow paths (isolating a main LNG source) from a BOG source (such as an LNG storage tank steam space) to an inlet of a pipeline and from an outlet of the pipeline to a BOG treatment system are established, BOG is led in to flow through the pipeline and is cooled by cold energy of the BOG, and the heated BOG is led out for treatment. And by monitoring the pipe wall temperature, calculating the cooling rate and / or the temperature gradient in real time, comparing the cooling rate and / or the temperature gradient with a preset limit value and dynamically adjusting the flow velocity of the introduced BOG, accurate control over the cooling process is achieved, thermal stress is effectively managed, and pipeline damage is avoided. The BOG cold energy is utilized, LNG loss is remarkably reduced, the operation cost is reduced, operation is simplified, safety controllability is improved, and environmental emission is reduced.

The invention provides BOG treatment equipment for an LNG receiving station and a BOG treatment process of the BOG treatment equipment, and relates to the technical field of BOG treatment of the LNG receiving station. A first compressor and a second compressor are arranged in parallel, and BOG conveyed out of the LNG receiving station can enter the first compressor or the second compressor; bOG can enter the first compressor or the second compressor selectively according to the load condition, the BOG compressed by the compressor enters the cooler, the BOG cooled by the cooler enters the immersed recondenser, in-station condensation recovery is achieved, LNG in the immersed recondenser is pressurized and enters the cooler, and the LNG in the immersed recondenser enters the cooler. The BOG from the outlet of the compressor in the cooler exchanges cold with the high-pressure LNG from the immersed recondenser, deep recovery of the BOG is realized by fully utilizing a cold source in the station, and the technical effect of recovering the BOG in an energy-saving and consumption-reducing manner is realized.

The invention discloses a control method and system for processing liquefied natural gas flow at an LNG leading-in terminal, and relates to the technical field of liquefied natural gas, and the control method comprises the steps of obtaining LNG terminal information, obtaining LNG historical transmission data according to the LNG terminal information, obtaining a BOG temperature influence coefficient according to the LNG historical transmission data, and obtaining BOG compression power parameter information according to the LNG terminal information. According to the method, the generation conditions of the BOG at different temperatures in the LNG storage structure of the LNG terminal are accurately analyzed through the BOG temperature influence coefficient, a basis is provided for follow-up LNG transmission control, the LNG control efficiency is improved, LNG transmission is controlled through LNG transmission speed information, the stability and reliability of LNG transmission are ensured, and the method is suitable for popularization and application. And overpressure or decompression caused by too high or too low transmission speed is avoided, the BOG compression power is ensured to be adjusted in time while the BOG compression power adjusting frequency is reduced through the BOG compression power adjusting period, and the stability of LNG is ensured.

The invention relates to the technical field of liquefied natural gas receiving stations, in particular to a BOG return gas treatment device and method and an LNG receiving station. The BOG return gas treatment device comprises a shipment return gas arm, a desuperheater, an LNG storage tank and a BOG compression assembly. The shipment air return arm is used for conveying BOG; the desuperheater is provided with a desuperheating inlet and a desuperheating outlet, the desuperheating inlet is communicated with the shipment air return arm, and the desuperheater is used for cooling BOG; the LNG storage tank is communicated with the temperature reduction outlet and is used for performing cryogenic liquid separation on BOG; the BOG compression assembly communicates with the LNG storage tank and is used for compressing BOG.

This disclosure relates to a BOG reliquefaction system, a method for reliquefying BOG in a reliquefaction system, and a method for operating a BOG reliquefaction system. The BOG reliquefaction system includes at least one liquefied natural gas (LNG) container, a BOG preheater, at least one BOG compressor having a BOG compressor cooler, and a BOG recondenser having a refrigeration cycle. The BOG reliquefaction system includes a separate liquid circuit with circulation of a liquid phase heat transfer fluid (HTF) to preheat the BOG from the LNG container before it enters the BOG compressor. The separate liquid circuit includes: a liquid pump configured to pump the HTF; a BOG preheater configured to perform heat exchange between the BOG and the HTF; a BOG recondenser located downstream of the BOG preheater; and a liquid trimming heater located downstream of the BOG recondenser configured to heat the HTF.

The invention provides a natural gas liquefaction device, and aims to solve the technical problem of poor applicability of BOG liquefaction equipment. The liquefying device comprises: a recovery assembly, which is internally provided with a liquefying chamber, and the bottom of the liquefying chamber is provided with a return pipe; one end of the connecting pipeline is communicated with the liquefaction cavity and BOG generation equipment, and the other end of the connecting pipeline penetrates into the recovery assembly and is communicated with the liquefaction cavity; the heat exchange assembly comprises a refrigeration part and a heat exchange part, the refrigeration part is arranged in the liquefaction cavity, and the heat exchange part is located outside the recovery assembly; wherein the end, far away from the liquefaction cavity, of the return pipe is located below the liquid level of liquefied natural gas in the BOG generation equipment, the end, far away from the liquefaction cavity, of the connecting pipeline is located above the liquid level of the liquefied natural gas in the BOG generation equipment, and a check valve is arranged on the return pipe. The liquefaction device has the advantage of being suitable for BOG recovery liquefaction work in various scenes.

The invention discloses a BOG reliquefaction recovery processing method and system, and the BOG reliquefaction recovery processing method comprises the following steps: when the water dew point of BOG raw material gas processed by a raw material gas drying device is smaller than a first preset value, the BOG raw material gas enters a liquefaction cold box device; adjusting a liquefaction cold box device, a refrigerant matching device and a refrigerant compression device, and circularly providing different cold quantities for the multi-level cold sections of the liquefaction cold box through multi-level compression of the refrigerant compression device and multi-level expansion cooling coupling of a corresponding expansion mechanism until the temperature of a backflow refrigerant reaches a first preset value; the treated BOG raw material gas is subjected to multi-level cooling by a liquefaction cold box device to form LNG (Liquefied Natural Gas); and the output quantity of the refrigerant compression device is adjusted to the maximum value, the refrigerant adding quantity is increased, the opening degree of an HV-1 throttling valve is increased, liquid in the denitrification flash evaporation device is controlled to be within a fifth threshold value range, and LNG is subjected to flash evaporation separation through the denitrification flash evaporation device and recycled into the LNG storage tank. The system and the method have the beneficial effects that BOG feed gas is liquefied to form LNG, and rapid recovery of BOG is realized.

The utility model relates to the technical field of cold insulation systems, in particular to an LNG (Liquefied Natural Gas) storage tank closed cold insulation system utilizing BOG (Boil Off Gas) cold energy. According to the technical scheme, mainly aiming at the problem of BOG cold energy waste caused by the fact that the cold energy of BOG is not utilized due to the fact that a direct compression process is adopted for BOG, the BOG cold energy recycling device comprises an LNG storage tank, an outer tank is arranged on the outer side of the LNG storage tank in a sleeving mode, a space is reserved between the LNG storage tank and the outer tank and used for flowing of cooling liquid, a liquid discharging pipe is arranged at the bottom of the outer tank, and the liquid discharging pipe is communicated with the LNG storage tank. A liquid inlet pipe is further mounted at the top of the outer tank; and the spraying assembly is arranged on the LNG storage tank and is used for uniformly discharging the cooling liquid. According to the LNG storage tank, the cooling capacity in BOG generated by evaporation of the liquefied natural gas in the LNG storage tank can be effectively utilized, meanwhile, the liquefied natural gas in the LNG storage tank is cooled, and potential safety hazards caused by the fact that the temperature of the liquefied natural gas is too high and the evaporation capacity is too large are effectively prevented.