Method and system for controlling the production of BOG boil-off gas

Abstract

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.

Description

Technical Field

[0001] This invention relates to the field of BOG evaporation gas technology, and more specifically, to a method and system for effectively controlling the generation of BOG evaporation gas. Background Technology

[0002] The main function of an LNG receiving terminal is to receive, store, and vaporize LNG (with a boiling point of approximately -162°C at one atmosphere) and supply it to users via natural gas pipelines. The entire production process at an LNG receiving terminal is a physical process, involving cryogenic unloading, cryogenic storage, cryogenic pressurization, heating and vaporization, and pipeline transportation. Boiling gas (BOG) generation is caused by various heat leaks from LNG storage tanks leading to temperature increases, as well as volume displacement between the LNG storage tank and external containers. The hazards of BOG include: excessive accumulation leading to overpressure in the LNG storage tank and potential explosion; and external combustion resulting in resource waste and environmental pollution. Therefore, it is necessary to reduce BOG generation.

[0003] Existing technologies are all improvements on the "re-condensation process," essentially focusing on how to recover BOG vapors. Currently, there are no processes or methods to suppress the generation of BOG vapors, which is done before BOG vapor recovery. This invention reduces the generation of BOG vapors at the source by reducing the actual pressure of BOG vapors in the storage tank. This method can significantly reduce the power consumption of BOG vapor recovery involved in the "re-condensation process," resulting in a higher cost-performance ratio.

[0004] Patent document CN103225740B (application number: 201310139365.8) discloses a BOG processing system for LNG receiving terminals that utilizes pressure energy. The system uses the pressure energy of the high-pressure LNG itself to absorb the low-pressure BOG discharged from the condensate LNG storage tank. The high-pressure LNG and low-pressure BOG are fully mixed and energy exchanged in a liquid-gas ejector mixer. The mixed fluid is medium-high pressure LNG. After being vaporized into medium-high pressure natural gas by a medium-high pressure vaporizer, the medium-high pressure LNG is provided to medium-high pressure natural gas users.

[0005] Patent document CN104913196B (application number: 201510393012.X) discloses a BOG processing technology and apparatus for normal operation of an LNG receiving station. BOG from the LNG storage tank is fed into a low-pressure BOG compressor and then into an LNG / BOG heat exchanger. LNG from the low-pressure LNG pipeline of the LNG low-pressure pump is transported into the LNG / BOG heat exchanger to exchange heat with the BOG at the outlet of the low-pressure BOG compressor. Finally, the BOG is condensed into a liquid state.

[0006] Patent document CN104964161A (application number: 201510424700.8) discloses a BOG recovery and processing method and system for an LNG receiving terminal, which sets up a BOG recovery and processing system for LNG receiving terminals without external output operation conditions; LNG in the BOG recondenser enters the LNG mother tank, and LNG in the LNG mother tank enters the external output loading system. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the purpose of this invention is to provide a method and system for controlling the generation of BOG evaporative gas.

[0008] A method for controlling BOG evaporation gas generation according to the present invention includes:

[0009] Step S1: Analyze and obtain all influencing parameters related to the generation of BOG vapor;

[0010] Step S2: Use a preset filter to filter all influencing parameters to obtain calculable, adjustable and most economical influencing parameters;

[0011] Step S3: Use the selected influencing parameters as adjustable parameters to suppress the generation of BOG evaporation gas.

[0012] Preferably, step S1 employs:

[0013] Step S1.1: Collect known causes of BOG vapor production and corresponding empirical formulas;

[0014] Step S1.2: Analyze and extract all influencing parameters from all empirical formulas;

[0015] All the empirical formulas mentioned include: empirical formulas for heat leakage in storage tanks, empirical formulas for heat leakage in pipelines, empirical formulas for atmospheric pressure changes, empirical formulas for low-pressure pump work, empirical formulas for external transport volume replacement, empirical formulas for unloading volume replacement, empirical formulas for heat leakage in ship holds, empirical formulas for unloading pump work, empirical formulas for flash evaporation inside tanks during unloading, and empirical formulas for tank truck volume replacement.

[0016] All the influencing parameters include: tank volume, number of tanks in the station, tank vapor pressure, tank vapor temperature, daily evaporation coefficient of the tank, BOG volume in the tank, low-pressure pump shaft power, low-pressure pump efficiency, number of low-pressure pumps in operation, LNG density, LNG latent heat of vaporization, LNG ship volume, LNG ship vapor pressure, LNG ship vapor temperature, LNG ship daily evaporation coefficient, BOG density, BOG molar mass, standard state pressure, standard state temperature, number of unloading pumps in operation, unloading pump efficiency, unloading pump power loss, unloading speed, heat leakage pipeline area, process pipeline heat absorption intensity, gas pressure change rate, number of loading skids, and loading return gas rate.

[0017] Preferably, the preset filter adopts:

[0018] Based on all influencing parameters, parameters related to the evaporation rate equation and the PR equation of state were selected.

[0019] f1(x1)=x1∈{δ fomula (x)};

[0020] Where x represents all influencing parameters; δ fomula This represents the parameter selection matrix involving the Hertz-Knudsen evaporation equation and the PR equation of state; x1 represents the parameters obtained through selection that are related to the evaporation rate equation and the PR equation of state.

[0021] Select adjustable parameters for the process based on the currently selected parameters;

[0022] f2(x2)=x2∈{δ technology (x1)}

[0023] Where, δ technology x1 represents the process parameter screening matrix; x2 represents the adjustable process parameters obtained through screening.

[0024] Based on the currently selected parameters, select the economic parameters for BOG evaporation gas;

[0025] f3(x3)=x3∈{δ score (x2)}

[0026] Where, δ score x3 represents the optimal parameter selection matrix; x3 represents the optimal parameter in terms of economic efficiency.

[0027] Preferably, the evaporation rate equation is:

[0028]

[0029] in, S represents the BOG evaporation rate; interface T represents the vapor-liquid phase contact area; LNG Indicates the temperature of the LNG inside the storage tank; M LNG p represents the molar mass of LNG; sat (T LNG ) indicates at temperature T LNG The corresponding saturation pressure inside the storage tank under the given conditions; p BOG Indicates the actual BOG vapor pressure inside the storage tank; α represents the adjustment coefficient; R represents the molar gas constant.

[0030] p sat The calculation method uses the Peng-Robinson equation of state:

[0031]

[0032]

[0033]

[0034]

[0035] f w =0.37464+1.54226ω-0.26992ω 2

[0036] Where T represents the temperature of the component; V represents the molar volume; P is the pressure of the component; P c T represents the critical pressure of the component; c Indicates the critical temperature of the component; T r The temperature at which the components are compared is indicated; ω represents the eccentricity factor.

[0037]

[0038] Where: M represents molar mass; V m m represents the gas volume; m represents the mass.

[0039] V m =V 罐 -V 液

[0040]

[0041] Where: h is the liquid level in the LNG storage tank; D represents the diameter of the storage tank; V 罐 Indicates the volume of the storage tank;

[0042] The adjustable parameters selected based on the currently screened parameters include: the pressure inside the LNG storage tank and the liquid level inside the LNG storage tank;

[0043] The economic parameters for BOG evaporation gas selected based on the currently selected parameters include: under unloading conditions, when the unloading speed is at its maximum, the liquid level change in the storage tank is not adjustable;

[0044] The economic parameter of the BOG vapor is the actual BOG vapor pressure p in the storage tank. BOG .

[0045] Preferably, the actual BOG evaporation gas pressure p inside the storage tank BoG The larger the BOG evaporation rate The smaller.

[0046] A system for controlling BOG evaporation gas generation according to the present invention includes:

[0047] Module M1: Analyzes and obtains all influencing parameters related to the generation of BOG evaporation gas;

[0048] Module M2: Uses a preset filter to filter all influencing parameters to obtain calculable, adjustable, and most economical influencing parameters;

[0049] Module M3: Uses the selected influencing parameters as adjustable parameters to suppress the generation of BOG evaporation gas.

[0050] Preferably, module M1 adopts:

[0051] Module M1.1: Collect known causes of BOG vapor production and corresponding empirical formulas;

[0052] Module M1.2: Analyzes and extracts all influencing parameters from all empirical formulas;

[0053] All the empirical formulas mentioned include: empirical formulas for heat leakage in storage tanks, empirical formulas for heat leakage in pipelines, empirical formulas for atmospheric pressure changes, empirical formulas for low-pressure pump work, empirical formulas for external transport volume replacement, empirical formulas for unloading volume replacement, empirical formulas for heat leakage in ship holds, empirical formulas for unloading pump work, empirical formulas for flash evaporation inside tanks during unloading, and empirical formulas for tank truck volume replacement.

[0054] All the influencing parameters include: tank volume, number of tanks in the station, tank vapor pressure, tank vapor temperature, daily evaporation coefficient of the tank, BOG volume in the tank, low-pressure pump shaft power, low-pressure pump efficiency, number of low-pressure pumps in operation, LNG density, LNG latent heat of vaporization, LNG ship volume, LNG ship vapor pressure, LNG ship vapor temperature, LNG ship daily evaporation coefficient, BOG density, BOG molar mass, standard state pressure, standard state temperature, number of unloading pumps in operation, unloading pump efficiency, unloading pump power loss, unloading speed, heat leakage pipeline area, process pipeline heat absorption intensity, gas pressure change rate, number of loading skids, and loading return gas rate.

[0055] Preferably, the preset filter adopts:

[0056] Based on all influencing parameters, parameters related to the evaporation rate equation and the PR equation of state were selected.

[0057] f1(x1)=x1∈{δ fomula (x)};

[0058] Where x represents all influencing parameters; δ fomula This represents the parameter selection matrix involving the Hertz-Knudsen evaporation equation and the PR equation of state; x1 represents the parameters obtained through selection that are related to the evaporation rate equation and the PR equation of state.

[0059] Select adjustable parameters for the process based on the currently selected parameters;

[0060] f2(x2)=x2∈{δ technology (x1)}

[0061] Where, δ technology x1 represents the process parameter screening matrix; x2 represents the adjustable process parameters obtained through screening.

[0062] Based on the currently selected parameters, select the economic parameters for BOG evaporation gas;

[0063] f3(x3)=x3∈{δ score (x2)}

[0064] Where, δ score x3 represents the optimal parameter selection matrix; x3 represents the optimal parameter in terms of economic efficiency.

[0065] Preferably, the evaporation rate equation is:

[0066]

[0067] in, BOG represents the evaporation rate; Sinterface represents the vapor-liquid phase contact area; TLNG represents the LNG temperature inside the tank; MLNG represents the molar mass of LNG; psat(TLNG) represents the LNG temperature at temperature T. LNG Under the corresponding conditions, the saturation pressure inside the storage tank; pBOG represents the actual BOG vapor pressure inside the storage tank; α represents the adjustment coefficient; R represents the molar gas constant.

[0068] p sat The calculation method uses the Peng-Robinson equation of state:

[0069]

[0070]

[0071]

[0072]

[0073] f w =0.37464+1.54226ω-0.26992ω 2

[0074] Where T represents the temperature of the component; V represents the molar volume; P is the pressure of the component; P c T represents the critical pressure of the component; c Indicates the critical temperature of the component; Tr The temperature at which the components are compared is indicated; ω represents the eccentricity factor.

[0075]

[0076] Where: M represents molar mass; V m m represents the gas volume; m represents the mass.

[0077] V m =V 罐 -V 液

[0078]

[0079] Where: h is the liquid level in the LNG storage tank; D represents the diameter of the storage tank; V 罐 Indicates the volume of the storage tank;

[0080] The adjustable parameters selected based on the currently screened parameters include: the pressure inside the LNG storage tank and the liquid level inside the LNG storage tank;

[0081] The economic parameters for BOG evaporation gas selected based on the currently selected parameters include: under unloading conditions, when the unloading speed is at its maximum, the liquid level change in the storage tank is not adjustable;

[0082] The economic parameter of the BOG vapor is the actual BOG vapor pressure p in the storage tank. BOG .

[0083] Preferably, the actual BOG evaporation gas pressure p inside the storage tank BOG The larger the BOG evaporation rate The smaller.

[0084] Compared with the prior art, the present invention has the following beneficial effects:

[0085] 1. The present invention suppresses the generation of BOG vapor by reducing the generation of BOG vapor at the source before BOG vapor recovery;

[0086] 2. This invention selects the most calculable, adjustable, and economical influencing parameters from dozens of influencing parameters, resulting in a higher cost-performance ratio;

[0087] 3. Reducing the generation of BOG vapors at the source can effectively reduce the harm caused by BOG;

[0088] 4. An interpretable parameter adjustment scheme is provided through an adjustable parameter filter, which helps on-site operators understand the adjustment operation;

[0089] 5. By suppressing the generation of BOG vapor, the pressure inside the LNG storage tank can be effectively maintained, thus ensuring safe production.

[0090] 6. By suppressing the generation of BOG evaporation gas, it can help optimize the energy consumption of the entire plant. Attached Figure Description

[0091] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0092] Figure 1 A flowchart illustrating a method for effectively controlling BOG evaporation gas generation. Detailed Implementation

[0093] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0094] Example 1

[0095] According to the present invention, a method for controlling BOG evaporation gas generation is provided, such as... Figure 1 As shown, it includes:

[0096] Step S1: Analyze and obtain all influencing parameters related to the generation of BOG vapors;

[0097] Step S2: Use a preset filter to filter all influencing parameters to obtain calculable, adjustable and most economical influencing parameters;

[0098] Step S3: Use the selected influencing parameters as adjustable parameters to suppress the generation of BOG evaporation gas.

[0099] Specifically, step S1 employs the following:

[0100] Step S1.1: Collect known causes of BOG vapor production and corresponding empirical formulas;

[0101] Step S1.2: Analyze and extract all influencing parameters from all empirical formulas;

[0102] All the empirical formulas mentioned include: empirical formulas for heat leakage in storage tanks, empirical formulas for heat leakage in pipelines, empirical formulas for atmospheric pressure changes, empirical formulas for low-pressure pump work, empirical formulas for external transport volume replacement, empirical formulas for unloading volume replacement, empirical formulas for heat leakage in ship holds, empirical formulas for unloading pump work, empirical formulas for flash evaporation inside tanks during unloading, and empirical formulas for tank truck volume replacement.

[0103]

[0104] All the influencing parameters include: tank volume, number of tanks in the station, tank vapor pressure, tank vapor temperature, daily evaporation coefficient of the tank, BOG volume in the tank, low-pressure pump shaft power, low-pressure pump efficiency, number of low-pressure pumps in operation, LNG density, LNG latent heat of vaporization, LNG ship volume, LNG ship vapor pressure, LNG ship vapor temperature, LNG ship daily evaporation coefficient, BOG density, BOG molar mass, standard state pressure, standard state temperature, number of unloading pumps in operation, unloading pump efficiency, unloading pump power loss, unloading speed, heat leakage pipeline area, process pipeline heat absorption intensity, gas pressure change rate, number of loading skids, and loading return gas rate.

[0105]

[0106] Specifically, the preset filter adopts:

[0107] Based on all influencing parameters, parameters related to the evaporation rate equation and the PR equation of state were selected.

[0108] f1(x1)=x1∈{δ fomula (x)};

[0109] Where x represents all influencing parameters; δ fomula This represents the parameter selection matrix involving the Hertz-Knudsen evaporation equation and the PR equation of state; x1 represents the parameters obtained through selection that are related to the evaporation rate equation and the PR equation of state.

[0110] Select adjustable parameters for the process based on the currently selected parameters;

[0111] f2(x2)=x2∈{δ technology (x1)}

[0112] Where, δ technology x1 represents the process parameter screening matrix; x2 represents the adjustable process parameters obtained through screening.

[0113] Based on the currently selected parameters, select the economic parameters for BOG evaporation gas;

[0114] f3(x3)=x3∈{δ score (x2)}

[0115] Where, δ score x3 represents the optimal parameter selection matrix; x3 represents the optimal parameter in terms of economic efficiency.

[0116] Specifically, the reason for BOG evaporation is that the restoration of vapor-liquid phase equilibrium is driven by the difference between liquid and gas pressures, which requires calculation using a molecular dynamics evaporation-condensation model; the BOG evaporation rate is calculated using the industry-recognized Hertz-Knudsen equation.

[0117] The Hertz-Knudsen equations employ:

[0118]

[0119] in, S represents the BOG evaporation rate; interface T represents the vapor-liquid phase contact area; LNG Indicates the temperature of the LNG inside the storage tank; M LNG p represents the molar mass of LNG. sat (T LNG ) indicates at temperature T LNG The corresponding saturation pressure inside the storage tank under the given conditions; p BOG The pressure represents the actual BOG vapor pressure inside the storage tank; α represents the adjustment coefficient, which ranges from 0 to 1; R represents the molar gas constant, which is 8.3145 kJ / (kmol·k).

[0120] p sat The calculation method uses the Peng-Robinson equation of state:

[0121]

[0122]

[0123]

[0124]

[0125] f w =0.37464+1.54226ω-0.26992ω 2

[0126] Where T represents the temperature of the component; V represents the molar volume; P is the pressure of the component; P c T represents the critical pressure of the component; c Indicates the critical temperature of the component; T r The relative temperature of the components is T / T. c ω represents the eccentricity factor;

[0127]

[0128] Where: M represents molar mass; V m m represents the gas volume; m represents the mass.

[0129] V m =V 罐 -V 液

[0130]

[0131] Where: h is the liquid level in the LNG storage tank; D represents the diameter of the storage tank; V 罐 Indicates the volume of the storage tank;

[0132] The adjustable parameters selected based on the currently screened parameters include: measurable parameters of BOG vaporized gas in the storage tank, including: pressure, temperature, liquid level, and density; wherein, the pressure and liquid level in the LNG storage tank are adjustable;

[0133] The economic parameters for BOG evaporation gas selected based on the currently selected parameters include: under unloading conditions, the unloading speed is generally set to the maximum value, so that the LNG ship's berthing time is shorter; under unloading conditions, when the unloading speed is at its maximum, the liquid level change in the storage tank cannot be adjusted.

[0134] The economic parameter of the BOG vapor is the actual BOG vapor pressure p in the storage tank. BOG .

[0135] Specifically, the actual BOG evaporation gas pressure p inside the storage tank BOG The larger the BOG evaporation rate The smaller the value, the higher the actual BOG evaporation gas pressure p inside the storage tank. BOG The smaller the value, the lower the BOG evaporation rate. The larger.

[0136] A system for controlling BOG evaporation gas generation according to the present invention includes:

[0137] Module M1: Analyzes and obtains all influencing parameters related to the generation of BOG evaporation gas;

[0138] Module M2: Uses a preset filter to filter all influencing parameters to obtain calculable, adjustable, and most economical influencing parameters;

[0139] Module M3: Uses the selected influencing parameters as adjustable parameters to suppress the generation of BOG evaporation gas.

[0140] Specifically, module M1 adopts:

[0141] Module M1.1: Collect known causes of BOG vapor production and corresponding empirical formulas;

[0142] Module M1.2: Analyzes and extracts all influencing parameters from all empirical formulas;

[0143] All the empirical formulas mentioned include: empirical formulas for heat leakage in storage tanks, empirical formulas for heat leakage in pipelines, empirical formulas for atmospheric pressure changes, empirical formulas for low-pressure pump work, empirical formulas for external transport volume replacement, empirical formulas for unloading volume replacement, empirical formulas for heat leakage in ship holds, empirical formulas for unloading pump work, empirical formulas for flash evaporation inside tanks during unloading, and empirical formulas for tank truck volume replacement.

[0144]

[0145] All the influencing parameters include: tank volume, number of tanks in the station, tank vapor pressure, tank vapor temperature, daily evaporation coefficient of the tank, BOG volume in the tank, low-pressure pump shaft power, low-pressure pump efficiency, number of low-pressure pumps in operation, LNG density, LNG latent heat of vaporization, LNG ship volume, LNG ship vapor pressure, LNG ship vapor temperature, LNG ship daily evaporation coefficient, BOG density, BOG molar mass, standard state pressure, standard state temperature, number of unloading pumps in operation, unloading pump efficiency, unloading pump power loss, unloading speed, heat leakage pipeline area, process pipeline heat absorption intensity, gas pressure change rate, number of loading skids, and loading return gas rate.

[0146]

[0147] Specifically, the preset filter adopts:

[0148] Based on all influencing parameters, parameters related to the evaporation rate equation and the PR equation of state were selected.

[0149] f1(x1)=x1∈{δ fomula (x)};

[0150] Where x represents all influencing parameters; δ fomula This represents the parameter selection matrix involving the Hertz-Knudsen evaporation equation and the PR equation of state; x1 represents the parameters obtained through selection that are related to the evaporation rate equation and the PR equation of state.

[0151] Select adjustable parameters for the process based on the currently selected parameters;

[0152] f2(x2)=x2∈{δ technology (x1)}

[0153] Where, δ technology x1 represents the process screening matrix; x2 represents the adjustable parameters of the screened process.

[0154] Based on the currently selected parameters, select the economic parameters for BOG evaporation gas;

[0155] f3(x3)=x3∈{δ score (x2)}

[0156] Where, δ score x3 represents the optimal parameter selection matrix; x3 represents the optimal parameter in terms of economic efficiency.

[0157] Specifically, the reason for BOG evaporation is that the restoration of vapor-liquid phase equilibrium is driven by the difference between liquid and gas pressures, which requires calculation using a molecular dynamics evaporation-condensation model; the BOG evaporation rate is calculated using the industry-recognized Hertz-Knudsen equation.

[0158] The Hertz-Knudsen equations employ:

[0159]

[0160] in, S represents the BOG evaporation rate; interface T represents the vapor-liquid phase contact area; LNG Indicates the temperature of the LNG inside the storage tank; M LNG p represents the molar mass of LNG. sat (T LNG ) indicates at temperature T LNG The corresponding saturation pressure inside the storage tank under the given conditions; p BOG The pressure represents the actual BOG vapor pressure inside the storage tank; α represents the adjustment coefficient, which ranges from 0 to 1; R represents the molar gas constant, which is 8.3145 kJ / (kmol·k).

[0161] p sat The calculation method uses the Peng-Robinson equation of state:

[0162]

[0163]

[0164]

[0165]

[0166] f w =0.37464+1.54226ω-0.26992ω 2

[0167] Where T represents the temperature of the component; V represents the molar volume; P is the pressure of the component; P c T represents the critical pressure of the component; c Indicates the critical temperature of the component; T r The relative temperature of the components is T / T. c ω represents the eccentricity factor;

[0168]

[0169] Where: M represents molar mass; V m m represents the gas volume; m represents the mass.

[0170] V m =V 罐 -V 液

[0171]

[0172] Where: h is the liquid level in the LNG storage tank; D represents the diameter of the storage tank; V 罐 Indicates the volume of the storage tank;

[0173] The adjustable parameters selected based on the currently screened parameters include: measurable parameters of BOG vaporized gas in the storage tank, including: pressure, temperature, liquid level, and density; wherein, the pressure and liquid level in the LNG storage tank are adjustable;

[0174] The economic parameters for BOG evaporation gas selected based on the currently selected parameters include: under unloading conditions, the unloading speed is generally set to the maximum value, so that the LNG ship's berthing time is shorter; under unloading conditions, when the unloading speed is at its maximum, the liquid level change in the storage tank cannot be adjusted.

[0175] The economic parameter of the BOG vapor is the actual BOG vapor pressure p in the storage tank. BOG .

[0176] Specifically, the actual BOG evaporation gas pressure p inside the storage tank BOG The larger the BOG evaporation rate The smaller the value, the higher the actual BOG evaporation gas pressure p inside the storage tank. BOG The smaller the value, the lower the BOG evaporation rate. The larger.

[0177] Those skilled in the art will understand that, besides implementing the system and its various devices, modules, and units provided by this invention in the form of purely computer-readable program code, the same functions can be achieved entirely through logical programming of the method steps, making the system and its various devices, modules, and units of this invention function in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers. Therefore, the system and its various devices, modules, and units provided by this invention can be considered as a hardware component, and the devices, modules, and units included therein for implementing various functions can also be considered as structures within the hardware component; alternatively, the devices, modules, and units for implementing various functions can be considered as both software modules implementing the method and structures within the hardware component.

[0178] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A method for controlling the generation of BOG vapor, characterized in that, include: Step S1: Analyze and obtain all influencing parameters related to the generation of BOG vapor; Step S2: Use a preset filter to filter all influencing parameters to obtain calculable, adjustable and most economical influencing parameters; Step S3: Use the screened influencing parameters as adjustable parameters to suppress the generation of BOG vapors; The preset filter uses: Based on all influencing parameters, parameters related to the evaporation rate equation and the PR equation of state were selected. ； in, This represents all influencing parameters; This represents the parameter selection matrix involved in the Hertz-Knudsen evaporation equation and the PR equation of state; This indicates that parameters related to the evaporation rate equation and the PR equation of state were obtained through screening. Select adjustable parameters for the process based on the currently selected parameters; in, This represents the process parameter selection matrix; This indicates the adjustable parameters of the process obtained through screening; Based on the currently selected parameters, select the economic parameters for BOG evaporation gas; in, A matrix representing the optimal selection of parameters for economic efficiency; Indicates the parameter that represents the best economic efficiency; The evaporation rate equation uses: in, Indicates BOG evaporation rate; Indicates the vapor-liquid phase contact area; Indicates the temperature of the LNG inside the storage tank; Indicates the molar mass of LNG; Indicates temperature The corresponding saturation pressure inside the storage tank under the given conditions; This indicates the actual BOG vapor pressure inside the storage tank; Indicates the adjustment coefficient; Represents the molar gas constant; The calculation method uses the Peng-Robinson equation of state: in, Indicates the temperature of the components; V Indicates molar volume; P It is the pressure of the components; P c Indicates the critical pressure of the component; T c Indicates the critical temperature of the component; T r Indicates the relative temperatures of the components; ω Indicates the eccentricity factor; in: Indicates molar mass; Indicates the volume of gas; Indicates quality; in: This refers to the liquid level height inside the LNG storage tank. Indicates the diameter of the storage tank; Indicates the volume of the storage tank; The adjustable parameters selected based on the currently screened parameters include: the pressure inside the LNG storage tank and the liquid level inside the LNG storage tank; The economic parameters for BOG evaporation gas selected based on the currently selected parameters include: under unloading conditions, when the unloading speed is at its maximum, the liquid level change in the storage tank is not adjustable; The economic parameter of the BOG vapor is the actual BOG vapor pressure in the storage tank. .

2. The method for controlling BOG evaporation gas generation according to claim 1, characterized in that, Step S1 adopts the following: Step S1.1: Collect known causes of BOG vapor production and corresponding empirical formulas; Step S1.2: Analyze and extract all influencing parameters from all empirical formulas; All the empirical formulas mentioned include: empirical formulas for heat leakage in storage tanks, empirical formulas for heat leakage in pipelines, empirical formulas for atmospheric pressure changes, empirical formulas for low-pressure pump work, empirical formulas for external transport volume replacement, empirical formulas for unloading volume replacement, empirical formulas for heat leakage in ship holds, empirical formulas for unloading pump work, empirical formulas for flash evaporation inside tanks during unloading, and empirical formulas for tank truck volume replacement. All the influencing parameters include: tank volume, number of tanks in the station, tank vapor pressure, tank vapor temperature, daily evaporation coefficient of the tank, BOG volume in the tank, low-pressure pump shaft power, low-pressure pump efficiency, number of low-pressure pumps in operation, LNG density, LNG latent heat of vaporization, LNG ship volume, LNG ship vapor pressure, LNG ship vapor temperature, LNG ship daily evaporation coefficient, BOG density, BOG molar mass, standard state pressure, standard state temperature, number of unloading pumps in operation, unloading pump efficiency, unloading pump power loss, unloading speed, heat leakage pipeline area, process pipeline heat absorption intensity, gas pressure change rate, number of loading skids, and loading return gas rate.

3. The method for controlling BOG evaporation gas generation according to claim 1, characterized in that, It also includes a storage tank, the actual BOG vapor pressure inside the storage tank. The larger the BOG evaporation rate The smaller.

4. A system for controlling the generation of BOG evaporation gas, characterized in that, include: Module M1: Analyzes and obtains all influencing parameters related to the generation of BOG vapors; Module M2: Uses a preset filter to filter all influencing parameters to obtain calculable, adjustable, and most economical influencing parameters; Module M3: Uses the screened influencing parameters as adjustable parameters to suppress the generation of BOG evaporation gas; The preset filter uses: Based on all influencing parameters, parameters related to the evaporation rate equation and the PR equation of state were selected. ； in, This represents all influencing parameters; This represents the parameter selection matrix involved in the Hertz-Knudsen evaporation equation and the PR equation of state; This indicates that parameters related to the evaporation rate equation and the PR equation of state were obtained through screening. Select adjustable parameters for the process based on the currently selected parameters; in, This represents the process parameter selection matrix; This indicates the adjustable parameters of the process obtained through screening; Based on the currently selected parameters, select the economic parameters for BOG evaporation gas; in, A matrix representing the optimal selection of parameters for economic efficiency; Indicates the parameter that represents the best economic efficiency; The evaporation rate equation uses: in, Indicates BOG evaporation rate; Indicates the vapor-liquid phase contact area; Indicates the temperature of the LNG inside the storage tank; Indicates the molar mass of LNG; Indicates temperature The corresponding saturation pressure inside the storage tank under the given conditions; This indicates the actual BOG vapor pressure inside the storage tank; Indicates the adjustment coefficient; Represents the molar gas constant; The calculation method uses the Peng-Robinson equation of state: in, Indicates the temperature of the components; V Indicates molar volume; P It is the pressure of the components; P c Indicates the critical pressure of the component; T c Indicates the critical temperature of the component; T r Indicates the relative temperatures of the components; ω Indicates the eccentricity factor; in: Indicates molar mass; Indicates the volume of gas; Indicates quality; in: This refers to the liquid level height inside the LNG storage tank. Indicates the diameter of the storage tank; Indicates the volume of the storage tank; The adjustable parameters selected based on the currently screened parameters include: the pressure inside the LNG storage tank and the liquid level inside the LNG storage tank; The economic parameters for BOG evaporation gas selected based on the currently selected parameters include: under unloading conditions, when the unloading speed is at its maximum, the liquid level change in the storage tank is not adjustable; The economic parameter of the BOG vapor is the actual BOG vapor pressure in the storage tank. .

5. The system for controlling BOG evaporation gas generation according to claim 4, characterized in that, The module M1 adopts: Module M1.1: Collect known causes of BOG vapor production and corresponding empirical formulas; Module M1.2: Analyzes and extracts all influencing parameters from all empirical formulas; All the empirical formulas mentioned include: empirical formulas for heat leakage in storage tanks, empirical formulas for heat leakage in pipelines, empirical formulas for atmospheric pressure changes, empirical formulas for low-pressure pump work, empirical formulas for external transport volume replacement, empirical formulas for unloading volume replacement, empirical formulas for heat leakage in ship holds, empirical formulas for unloading pump work, empirical formulas for flash evaporation inside tanks during unloading, and empirical formulas for tank truck volume replacement. All the influencing parameters include: tank volume, number of tanks in the station, tank vapor pressure, tank vapor temperature, daily evaporation coefficient of the tank, BOG volume in the tank, low-pressure pump shaft power, low-pressure pump efficiency, number of low-pressure pumps in operation, LNG density, LNG latent heat of vaporization, LNG ship volume, LNG ship vapor pressure, LNG ship vapor temperature, LNG ship daily evaporation coefficient, BOG density, BOG molar mass, standard state pressure, standard state temperature, number of unloading pumps in operation, unloading pump efficiency, unloading pump power loss, unloading speed, heat leakage pipeline area, process pipeline heat absorption intensity, gas pressure change rate, number of loading skids, and loading return gas rate.

6. The system for controlling BOG evaporation gas generation according to claim 4, characterized in that, It also includes a storage tank, the actual BOG vapor pressure inside the storage tank. The larger the BOG evaporation rate The smaller.

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