A management method and management system for the cold cabin gas test operation of an LNG ship

Abstract

The present invention relates to the technical field of cold tank gas testing, and particularly to a management method and a management system for cold tank gas testing operations of an LNG ship, including: connecting an LNG filling ship and the integrated automation system of the LNG ship through the management system, the management system obtaining data information, and then the management system establishing a cold tank gas testing management model according to the data information; the management system checking the boundary conditions of the cold tank gas testing operations, and then setting a preliminary LNG filling rate and predicting the maximum LNG consumption; the management system controlling the start of the cold tank gas testing operations; and iteratively obtaining the data information through the management system and dynamically adjusting the LNG filling rate during the cold tank gas testing operations to implement the cold tank gas testing operations of the LNG ship. The present invention reduces the probability of accidental release accidents of gaseous BOG, comprehensively grasps the alarm situation during the cold tank gas testing operations, and thus ensures the economy and safety of the cold tank gas testing of the LNG ship.

Description

Technical Field

[0001] The present invention relates to the technical field of cold tank gas testing technology for LNG ships, and particularly to a management method and management system for cold tank gas testing operations of LNG ships. Background Art

[0002] During the construction of LNG ships, the cold tank gas testing process plays an important role in process verification. It ensures the quality of the cargo tank containment system through the inspection of low-temperature resistance functions. Traditionally, the cold tank gas testing of LNG ships needs to be carried out at the receiving terminal, but this process is accompanied by multiple risks. Due to the large volume and diverse types of LNG ship cargo tanks, it is difficult to control the generation of BOG (boil-off gas). The flow rate of LNG injected at the terminal is unstable, making it difficult to accurately predict the LNG consumption. This not only prolongs the cold tank gas testing cycle but also leads to overfilling and waste of LNG. In addition, the instability of BOG during the cold tank gas testing process is prone to cause spills, posing challenges to the safety of LNG ships. Excessive LNG filling also means that it is necessary to return to the terminal for reverse transportation, which not only increases the cost of LNG ship construction but also brings many inconveniences. Summary of the Invention

[0003] The present invention aims to at least solve one of the technical problems existing in the related art. For this purpose, the present invention provides a management method and management system for cold tank gas testing operations of LNG ships, which solves the technical problems of difficult operation and high risk coefficient in cold tank gas testing of LNG ships in the prior art. The present application accurately adjusts the LNG filling volume according to the needs of the cold tank gas testing process, maintains the stable generation of BOG in the tank, anticipates and orderly processes the large-scale BOG generated by the cold tank gas testing, reduces the probability of accidental release accidents of gaseous BOG, comprehensively grasps the alarm situation during the process, and thus ensures the safety of cold tank gas testing of LNG ships, realizes cold tank gas testing of LNG ships without liquid LNG, saves the injected LNG volume, and does not need to return LNG to the LNG terminal, saving costs.

[0004] The present invention provides a management method for cold tank gas testing operations of LNG ships, including the following steps:

[0005] S1: Establish a management system, use the management system to connect the integrated automation system of the LNG filling ship and the integrated automation system of the LNG ship. The management system obtains the data information of the LNG filling ship and the LNG ship, and then the management system establishes a cold tank gas testing management model according to the data information, and connects the cargo tanks of the LNG filling ship and the LNG ship through pipelines;

[0006] S2: The management system checks the boundary conditions of the cold tank gas testing operation, and then sets the initial LNG filling rate and predicts the maximum LNG consumption;

[0007] S3: The management system controls the LNG bunkering vessel to fill LNG into the cargo tank at the initial LNG bunkering rate and starts the cold tank gas test operation;

[0008] S4: Iterating the acquired data information through the management system and dynamically adjusting the LNG filling rate during the cold tank gas trial operation to implement the cold tank gas trial operation on the LNG ship.

[0009] A further improvement of the cold tank gas test operation management method of an LNG carrier according to the present invention is that the cold tank gas test management model is:

[0010]

[0011] in, Indicates the LNG filling rate, represents the specific enthalpy of LNG, Indicates the amount of BOG discharged per unit time, represents the BOG specific enthalpy, represents the heat transfer coefficient of the enclosure system, represents the heat transfer area of the cargo hold, Indicates the cabin temperature. Indicates the ambient temperature, Indicates the gaseous BOG mass in the cabin, represents the specific heat capacity of gas at constant volume; represents the heat transfer loss of the cargo hold containment system, Indicates the cargo hold volume, represents the gas constant, Indicates the allowable pressure fluctuation range of the containment system. represents the initial filling rate, represents the proportional control coefficient, Indicates the combined BOG processing capacity of the two ships. Indicates time.

[0012] A further improvement of the cold tank gas trial operation management method of an LNG carrier according to the present invention is that the boundary conditions include the temperature of the LNG injected by the LNG bunkering ship, confirmation of the BOG combined processing capacity of the two ships, measurement of the enthalpy value of the LNG carrier's cargo hold in a hot tank state, determination of the temperature drop gradient, determination of the allowable pressure fluctuation range of the containment system, and determination of the ambient temperature. The combined BOG processing capacity of the two ships is the amount of BOG processed per unit time by the BOG processing equipment of the two ships.

[0013] A further improvement of the LNG carrier cold tank gas trial operation management method of the present invention is that S4 further includes the following steps:

[0014] The management system measures the BOG generation during the cold tank gas test operation and analyzes whether BOG overflow will occur based on the combined BOG processing capabilities of the two ships;

[0015] If the result is yes, the management system adjusts the LNG filling rate;

[0016] If the result is no, the management system keeps the LNG filling rate unchanged.

[0017] A further improvement of a management method for cold tank gas test operation of an LNG ship according to the present invention is that S4 further includes the following steps:

[0018] During the cold tank gas test operation, the management system starts the dual - ship BOG treatment equipment, and processes the BOG generated during the cold tank gas test operation through the dual - ship BOG treatment equipment to keep the cargo tank pressure of the LNG ship stable.

[0019] A further improvement of a management method for cold tank gas test operation of an LNG ship according to the present invention is that S4 further includes the following steps:

[0020] When the LNG filling rate remains unchanged and the gas test temperature of the cargo tank reaches the set value, enter the cold - preservation stage of the cold tank gas test operation, maintain the set time of the cold - preservation stage, and at the same time the management system checks the safety data of the LNG ship. The safety data includes the temperature data of the LNG ship and the function data of the containment system, and judges whether there is any abnormality or fault;

[0021] If there is no abnormality or fault, it is judged that the cold tank gas test operation can be continued. After maintaining the set time of the cold - preservation stage, the management system completes the evaluation of the containment system of the LNG ship, and the cold tank gas test operation ends;

[0022] If there is an abnormality or fault, the management system suspends the cold tank gas test operation and records the fault information.

[0023] A further improvement of a management method for cold tank gas test operation of an LNG ship according to the present invention is that during the cold - preservation stage, there is no liquid LNG remaining in the cargo tank of the LNG ship. After the cold - preservation stage ends, the LNG output by the LNG filling ship is less than the predicted maximum LNG consumption, and the management system completes the evaluation of the containment system of the LNG ship.

[0024] A further improvement of a management method for cold tank gas test operation of an LNG ship according to the present invention is that after the management system calculates the BOG generation amount during the cold tank gas test operation, it further includes the following steps:

[0025] The management system sequentially starts the dual - ship BOG treatment equipment, and the sequential start order is the fuel equipment of the LNG filling ship and the LNG ship, the re - liquefaction equipment of the LNG filling ship, the re - liquefaction equipment of the LNG ship, the GCU equipment of the LNG filling ship, and the GCU equipment of the LNG ship;

[0026] When all the BOG treatment equipment of the two ships is started, if the BOG generation volume still exceeds 90% of the combined BOG treatment capacity of the two ships, it is analyzed that there will be a risk of BOG overflow;

[0027] Adjust the LNG filling rate until the BOG generation volume is less than 90% of the combined BOG treatment capacity of the two ships and all the BOG treatment equipment of the two ships is started, so as to dynamically adjust the LNG filling rate.

[0028] An LNG ship cold tank gas test operation management system is used to execute the LNG ship cold tank gas test operation management method as described above. The management system includes a cold tank gas test data module, a cold tank gas test heat balance calculation module, a cold tank gas test filling rate control module, and a cold tank gas test alarm program processing module that are signal-connected.

[0029] The cold tank gas test data module is used to obtain data information;

[0030] The cold tank gas test heat balance calculation module is used to establish a cold tank gas test management model for calculating the BOG generation volume and the cargo tank pressure;

[0031] The cold tank gas test filling rate control module is used to control the LNG filling rate;

[0032] The cold tank gas test alarm program processing module is used to detect whether there is a failure in the containment system and to send out alarm information.

[0033] A further improvement of the LNG ship cold tank gas test operation management system of the present invention is that the cold tank gas test heat balance calculation module is connected to the BOG treatment equipment of the two ships. The BOG treatment equipment of the two ships includes the fuel equipment of the LNG filling ship, the fuel equipment of the LNG ship, the reliquefaction equipment of the LNG filling ship, the reliquefaction equipment of the LNG ship, the GCU equipment of the LNG filling ship, and the GCU equipment of the LNG ship.

[0034] The present invention realizes the unification of data collection and BOG control, enabling unified detection and management in the cold cargo tank gas test operation; it can quantitatively analyze the BOG overflow probability in the cold cargo tank gas test operation, ensuring the safety of the LNG ship's cargo containment system; it realizes precise control and dynamic adjustment of LNG filling during the cold cargo tank gas test operation, dynamically adjusting the LNG filling rate and filling volume; during the cold preservation stage of the LNG ship's cargo tank temperature drop, it keeps no liquid LNG in the LNG ship, reducing the LNG consumption and realizing the economy of the cold cargo tank gas test. If problems are found during the inspection of the containment system, since the tank is in a dry state, replenishment measures can be taken for the LNG cargo tank in a timely manner, making it easy to control the risk points; the establishment of the cold cargo tank gas test dynamic model realizes the dynamic process control of the cold cargo tank gas test, dynamically adjusting the control target priority, preventing the risk of BOG overflow, automatically quantitatively analyzing the overflow risk, and enhancing the safety of the cold cargo tank gas test operation; it realizes real-time, accurate and dynamic prediction and control of the filling volume of the LNG filling ship and the BOG generated in the cold cargo tank gas test, improving the efficiency of large-scale handling of cold cargo tank BOG and ensuring the smooth and efficient process of the cold cargo tank gas test; it realizes the intelligent auxiliary function for the cold cargo tank gas test operation of the LNG ship, including simply completing the verification of the functional integrity of the LNG ship's containment system according to the established procedure.

[0035] Additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0037] Figure 1 It is a block diagram of a method for managing the cold cargo tank gas test operation of an LNG ship provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] To make the objectives, technical solutions and advantages of the present invention clearer, the following will clearly and completely describe the technical solutions in the present invention with reference to the drawings in the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope protected by the present invention. The following embodiments are used to illustrate the present invention, but cannot be used to limit the scope of the present invention.

[0039] The following will be combined with Figure 1A method for managing the cold cargo hold gas test operation of an LNG ship according to the present invention includes the following steps:

[0040] S1: Establish a management system. Use the management system to connect the integrated automation system of the LNG filling ship and the integrated automation system of the LNG ship. The management system obtains the data information of the LNG filling ship and the LNG ship. Then, the management system establishes a cold cargo hold gas test management model based on the data information, and connects the cargo holds of the LNG filling ship and the LNG ship through pipelines;

[0041] S2: The management system checks the boundary conditions of the cold cargo hold gas test operation, and then sets the initial LNG filling rate and predicts the maximum LNG consumption;

[0042] S3: The management system controls the LNG filling ship to fill LNG into the cargo hold at the initial LNG filling rate and starts the cold cargo hold gas test operation;

[0043] S4: Iteratively obtain the data information through the management system and dynamically adjust the LNG filling rate during the cold cargo hold gas test operation to implement the cold cargo hold gas test operation of the LNG ship.

[0044] In a preferred embodiment of the method for managing the cold cargo hold gas test operation of an LNG ship according to the present invention, the cold cargo hold gas test management model is:

[0045]

[0046] Where, represents the LNG filling rate, with the unit of kg / s, represents the specific enthalpy of LNG, with the unit of kJ / kg, represents the BOG discharge amount per unit time, with the unit of kg / s, represents the specific enthalpy of BOG, with the unit of kJ / kg, represents the heat transfer coefficient of the containment system, with the unit of W / m 2 ·K, represents the heat transfer area of the cargo hold, with the unit of m 2 , represents the temperature inside the cargo hold, with the unit of K, represents the ambient temperature, with the unit of K, represents the mass of gaseous BOG inside the cargo hold, with the unit of kg, represents the specific heat capacity at constant volume of the gas, with the unit of kJ / kg·K; represents the heat transfer loss of the cargo hold containment system, with the unit of W, represents the volume of the cargo hold, with the unit of m 3 , represents the gas constant, with the unit of J / kg·K, represents the allowable pressure fluctuation range of the containment system, with the unit of Pa, represents the initial filling rate, with the unit of kg / s, represents the proportional control coefficient, represents the dual-ship BOG combined processing capacity, with the unit of kg / s, represents time, with the unit of s, where 1W = 0.001kJ / s, 1J = 1m 3 / Pa.

[0047] Specifically, the boundary conditions include the LNG temperature injected by the LNG filling ship, confirming the dual-ship BOG combined processing capacity, measuring the enthalpy value of the cargo hold of the LNG ship in the hot hold state, determining the temperature drop gradient, determining the allowable pressure fluctuation range of the containment system, and determining the ambient temperature. The dual-ship BOG combined processing capacity is the amount of BOG processed by the dual-ship BOG processing equipment per unit time.

[0048] Furthermore, S4 also includes the following steps: The management system calculates the amount of BOG generated during the cold hold gas test operation and analyzes whether BOG will overflow based on the dual-ship BOG combined processing capacity;

[0049] If the result is yes, the management system adjusts the LNG filling rate;

[0050] If the result is no, the management system keeps the LNG filling rate unchanged, that is, the control system keeps the current control program unchanged.

[0051] Specifically, when the management system analyzes that there is no risk of BOG overflow and the cargo hold pressure remains stable, the LNG filling rate remains unchanged at this time; when the LNG filling rate remains unchanged and the gas test temperature of the cargo hold reaches the set value, it enters the cold insulation stage of the cold hold gas test operation, maintains the set time of the cold insulation stage, and at the same time the management system checks the safety data of the LNG ship. The safety data includes the temperature data of the LNG ship and the function data of the containment system, and judges whether there are any abnormalities or faults; during the cold insulation stage, there is no excessive liquid LNG remaining in the cargo hold of the LNG ship. After the cold insulation stage ends, the amount of LNG output by the LNG filling ship is less than the predicted maximum LNG consumption, and the management system completes the evaluation of the containment system of the LNG ship; if there are no abnormalities or faults, it is judged that the cold hold gas test operation can be continued, maintains the set time of the cold insulation stage, and the management system completes the evaluation of the containment system of the LNG ship, and the cold hold gas test operation ends; if there are abnormalities or faults, the management system suspends the cold hold gas test operation and records the fault information.

[0052] Furthermore, S4 also includes the following steps: During the cold hold gas test operation, the management system starts the dual-ship BOG processing equipment and processes the BOG generated during the cold hold gas test operation through the dual-ship BOG processing equipment to keep the cargo hold pressure of the LNG ship stable.

[0053] Specifically, after the management system calculates the BOG generation amount during the cold cargo hold gas test operation, the following steps are further included: The management system sequentially starts the BOG treatment equipment of the two ships, and the sequential start order is the fuel equipment of the LNG bunker ship and the LNG ship, the re-liquefaction equipment of the LNG bunker ship, the re-liquefaction equipment of the LNG ship, the GCU equipment of the LNG bunker ship, and the GCU equipment of the LNG ship; When all the BOG treatment equipment of the two ships is started, if the BOG generation amount still exceeds 90% of the combined BOG treatment capacity of the two ships, it is analyzed that there is a risk of BOG overflow; Adjust the LNG filling rate until the BOG generation amount is less than 90% of the combined BOG treatment capacity of the two ships and all the BOG treatment equipment of the two ships is started, so as to achieve dynamic adjustment of the LNG filling rate.

[0054] An LNG ship cold cargo hold gas test operation management system is used to execute the above-mentioned LNG ship cold cargo hold gas test operation management method. The management system includes a cold cargo hold gas test data module, a cold cargo hold gas test heat balance calculation module, a cold cargo hold gas test filling rate control module, and a cold cargo hold gas test alarm program processing module that are signal-connected. The cold cargo hold gas test data module is used to obtain data information; The cold cargo hold gas test heat balance calculation module is used to establish a cold cargo hold gas test management model to calculate the BOG generation amount and the cargo hold pressure; The cold cargo hold gas test filling rate control module is used to control the LNG filling rate; The cold cargo hold gas test alarm program processing module is used to detect whether there is a failure in the containment system and to send out alarm information.

[0055] Furthermore, the cold cargo hold gas test heat balance calculation module is connected to the BOG treatment equipment of the two ships. The BOG treatment equipment of the two ships includes the fuel equipment of the LNG bunker ship, the fuel equipment of the LNG ship, the re-liquefaction equipment of the LNG bunker ship, the re-liquefaction equipment of the LNG ship, the GCU (Gas Combustion Unit) equipment of the LNG bunker ship, and the GCU equipment of the LNG ship.

[0056] The management method and management system in this application are used for the functional verification of the cold cargo hold gas test operation of the LNG bunker ship for the LNG ship. By comprehensively connecting the management system with the integrated automation systems (IAS) of the LNG bunker ship and the LNG ship respectively, it is possible to monitor and control the control system parameters of the two ships (LNG bunker ship and LNG ship), and through the connection of the process pipelines between the two ships, that is, the liquid phase is connected to the liquid phase and the gas phase is connected to the gas phase, which is convenient for carrying out the cold cargo hold gas test operation.

[0057] The management system utilizes the existing integrated automation system (IAS) and boil-off gas (BOG) processing equipment of the LNG bunker vessel and the LNG carrier. The system can accurately control the LNG bunkering rate of the LNG bunker vessel. Based on the real-time data of the cold cargo hold, during the temperature drop process and the cold insulation process of the cold cargo hold gas test, the management system jointly processes the generated BOG and optimizes the LNG injection volume, maintaining the state of no liquid LNG in the LNG cargo hold, achieving the minimum filling volume, and simultaneously completing the functional detection and evaluation of the LNG carrier's containment system. Through the data linkage and real-time control of the two vessels, the cold cargo hold gas test cycle is shortened, the risk of BOG overflow during the cold cargo hold gas test is effectively prevented, the safety and economy of the cold cargo hold gas test operation process are improved, and the purpose of energy conservation and environmental protection is achieved.

[0058] The cold cargo hold gas test data module includes a data acquisition unit and a data storage and analysis unit. The data acquisition unit is connected to the two IAS systems of the LNG bunker vessel and the LNG carrier respectively through the inter-ship cross-connected data line and communication protocol for data acquisition to obtain data information, which includes environmental information, cold cargo hold gas test analysis information of the LNG carrier's cargo hold containment system, and LNG bunker vessel bunkering information.

[0059] Specifically, the environmental information includes air and seawater temperatures.

[0060] Specifically, the cold cargo hold gas test function analysis information of the LNG carrier's cargo hold containment system includes data such as the cargo hold type, capacity, designed BOR value, cargo hold temperature, gaseous pressure and density in the LNG carrier's cargo hold, LNG liquid level in the LNG carrier's cargo hold, insulation layer temperature of the LNG carrier's cargo hold, insulation layer nitrogen pressure, measured temperature at key cold points in the ship's hull, etc., as well as data required by the LNG carrier's process specification, such as safety alarm values related to the cold cargo hold gas test of the LNG carrier's cargo hold containment system.

[0061] Specifically, the LNG bunker vessel bunkering information includes data such as LNG bunkering temperature, flow rate, and the amount of returned BOG to be processed.

[0062] The data storage and analysis unit, according to the LNG carrier's cargo hold type (for different LNG carrier cargo hold types: C-type, B-type, and membrane type), capacity, and the status information of the containment system, compares the cargo hold characteristics to find the LNG injection volume and the temperature field model of the cargo containment system during the cold cargo hold gas test operation of the same type of cargo hold in the stored data, selects the cold cargo hold gas test operation temperature drop curve, and based on the empirical rule, determines the LNG bunkering rate in the initial stage, such as the initial bunkering rate not exceeding 30% of the design value, and predicts the maximum LNG consumption value of the cold cargo hold gas test operation. The information data and the initially selected LNG bunkering rate will be transmitted to the cold cargo hold gas test bunkering rate control module and the cold cargo hold gas test heat balance calculation module for processing.

[0063] The data storage and analysis unit is used for data storage and analysis, including the temperature and pressure change data inside and outside the cargo hold during the cold hold gradient temperature drop stage and the continuous cold insulation stage, such as the data required by the LNG ship process specification and the cold hold gas test models of various cargo hold insulation systems, such as the temperature, pressure, and liquid cargo insulation layer temperature change data of the LNG ship.

[0064] The data storage and analysis unit stores and preprocesses the real-time cold hold gas test operation data collected, comprehensively evaluates the cold hold gas test operation, and provides support for the detection and implementation of subsequent procedures.

[0065] The cold hold gas test heat balance calculation module first checks and confirms the boundary conditions of the cold hold gas test operation. The inspection and determination of the boundary conditions include: checking and determining the temperature of the LNG injected (output) by the LNG filling ship (such as -160±2°C); calculating and confirming the maximum BOG treatment capacity of the dual-ship joint treatment; measuring and confirming the enthalpy value of the LNG ship in the hot hold state, with a cold hold temperature drop gradient of 10°-15°C; the cargo hold pressure fluctuation ≤ 5% of the pressure set value, and checking and measuring the temperature of the cold hold gas test environment conditions.

[0066] After the cold hold gas test data module selects the cargo hold temperature drop curve of the LNG ship, the cold hold gas test heat balance calculation module establishes a management model for the cold hold gas test operation corresponding to the cargo hold type of the LNG ship (for LNG ship holds with different materials and different insulation performances) based on the input operation condition data, the cargo hold heat balance calculation equation, the cargo hold insulation performance, the thermal conductivity of the liquid cargo hold wall, and the wall contact area, etc., and predicts the LNG filling volume during the cold hold stage and the generation amount of cold hold evaporated BOG.

[0067] Based on the calculation of the enthalpy value and the calculation of the cargo hold heat transfer value using parameters such as the temperature, volume, density, and pressure of the gaseous BOG inside the cargo hold itself, the inner surface area of the cargo hold, etc., a corresponding type of cold hold gas test dynamic model is established. Through this model, the management system can more accurately control the LNG filling rate and optimize the cold hold gas test operation process.

[0068] Specifically, adjust to keep the cargo hold free of liquid LNG, and the cargo hold of the LNG ship is in a pressure stable state (the overflow BOG is processed by the dual-ship BOG treatment equipment according to the procedure). The filling rate control module dynamically adjusts the filling rate based on the heat balance calculation result to maintain the pressure stability of the LNG cargo hold and avoid excessive retention of liquid LNG.

[0069] The cold hold gas test heat balance calculation module uses the FLUENT advanced simulation software to numerically simulate the cargo hold thermal environment of the LNG ship during the cold hold process, verify the generation amount of BOG, correct the LNG filling volume during the cold hold gas test, and provide real-time feedback to the filling rate control module. Compare the cumulative filling volume and the timed filling volume with the real-time BOG generation amount during the cold hold gas test of the LNG ship to verify the performance of the LNG ship cargo hold.

[0070] Cold cabin gas test heat balance calculation module, which evaluates the dynamic relationship between the injection rate of the LNG filling ship and the BOG generation amount during the cold cabin process of the LNG ship in the hot cabin state. After the two-ship process connection, it calculates the dynamic BOG treatment amount and corrects the BOG prediction value.

[0071] The cold cabin gas test filling rate control module adjusts the LNG injection rate of the filling ship by sending flow control instructions to the LNG filling ship to control the cold cabin temperature drop gradient; and controls the start and stop of the two-ship combined BOG treatment equipment to keep the cargo hold of the LNG ship in a pressure stable state.

[0072] Compare the predicted maximum BOG generation value of the LNG ship with the total combined BOG treatment capacity of the two ships. When the predicted BOG generated during the cold cabin gas test is less than the combined BOG treatment capacity of the two ships, first start the two-ship BOG treatment equipment in sequence to treat the BOG generated during the cold cabin until all the BOG generated during the cold cabin is completely treated. The management system counts the number of started BOG treatment equipment and the real-time total BOG treatment amount, predicts the LNG filling amount, and feeds back the output result.

[0073] When the combined BOG treatment capacity of the two ships is fully started and still less than the predicted BOG emission value generated during the cold cabin, ensure that the generated BOG emission does not exceed 90% of the combined BOG treatment capacity of the two ships, that is, there is a risk of BOG overflow (define the BOG overflow risk greater than the set value of 1, BOG overflow risk = the maximum BOG generation value during the cold cabin gas test operation of the LNG ship / the combined BOG treatment capacity of the two ships). Use the cold cabin gas test dynamic model to update the LNG injection rate, find the optimal BOG generation amount, and transmit control signals to the cold cabin gas test filling rate control module and the cold cabin gas test alarm program processing module for processing. Under the set LNG cargo hold temperature drop gradient, accurately control the LNG filling amount to ensure that the BOG generation amount matches the combined BOG treatment capacity of the two ships, so as to realize the dynamic adjustment of the LNG injection rate and filling amount.

[0074] The cold cabin gas test filling rate control module adjusts and accurately controls the filling rate of the LNG filling ship by communicating with the IAS system of the LNG filling ship in real time, and compares the predicted LNG consumption value with the actual LNG filling value. During the cold cabin gas test of the LNG ship's cargo hold, through the detection and control of the management system, always keep the LNG ship's cargo hold in a dry state without liquid LNG until the functional verification of the cold cabin gas test of the LNG ship is completed, without the LNG ship returning too much LNG to the LNG filling ship. Achieve the most economical cold cabin gas test operation and save the injected LNG amount. If there is a failure in the cargo hold containment system, due to the dry state inside the cabin, replenishment measures can be taken for the LNG cargo hold in time, making it easy to control the risk points.

[0075] The cold cargo hold gas test alarm program processing module, after receiving the information of the above module, checks the BOG overflow risk during the cold cargo hold gas test of the LNG carrier by the LNG filling ship and checks the alarm status of the LNG carrier's cargo containment system during the cold cargo hold gas test, including detecting the temperature of the cargo hold and the temperature change of the insulation layer of the containment system, evaluating the safety status of the cold cargo hold gas test process. When the BOG overflow risk exceeds the set value 1, the system automatically issues a warning signal and reduces the LNG injection volume. When a critical alarm appears in the alarm status check of the LNG carrier's cargo containment system, the management system automatically issues an alarm signal, applies to suspend the cold cargo hold gas test operation, and checks the reasons. The LNG carrier gas test alarm program processing module sets the global target of the BOG processing capacity, judges whether the BOG growth rate is controllable, evaluates and analyzes the probability of BOG overflow risk during the cold cargo hold gas test, quantitatively analyzes the BOG generation data, compares it with the capacity of the BOG processing equipment, and calculates the BOG overflow risk.

[0076] When the BOG overflow risk is greater than 1, it represents a high probability of BOG overflow risk. At the same time, monitor the cargo hold pressure of the LNG carrier to determine whether the status of the liquid cargo hold is normal, evaluate the impact of the BOG generation volume on the cargo hold pressure, and output an alarm signal when the cargo hold pressure is too high and an alarm is generated, so as to achieve the safety management of the cold cargo hold gas test of the LNG filling ship.

[0077] The cold cargo hold gas test alarm program processing model will refer to the process design values to conduct a safety alarm check on the cold cargo hold gas test operation. When the duration of the real-time unit cold cargo hold temperature drop gradient exceeds the data threshold of the process specification and test requirements, or the probability of potential BOG overflow risk is high, or a critical alarm occurs in the monitoring of the key data of the cargo hold containment system, the system automatically issues a warning signal. The LNG carrier gas test alarm program processing module can conduct a precise safety assessment and quantitative analysis on the cold cargo hold gas test operation of the LNG carrier, ensuring the safety of the LNG carrier's cargo containment system during the cold cargo hold gas test operation.

[0078] When the duration of the real-time unit cold cargo hold temperature drop gradient does not exceed the data threshold of the process specification and test requirements, or the BOG overflow risk is less than or equal to the set value 1, or a critical alarm appears in the alarm status check of the LNG carrier's cargo containment system, continue to inject LNG and the cold cargo hold operation of the LNG tank can continue.

[0079] When the cold cabin gas test temperature in the cargo hold reaches the set value (for example, when it reaches -130° to -140° and maintains for a certain period of time), it enters the cold insulation stage of the LNG in the cabin. The cold cabin gas test alarm program processing module of the LNG ship analyzes according to the distribution state of the temperature field in the LNG cabin, including the data inspection of the insulation layer temperature, checking the comparison data of the data with the designed data of the data comparison data module, and judging whether the function of the cargo containment system is within the normal range; assuming that the heat infiltrating into the cargo hold environment of the LNG ship's containment system is constant, calculating the balance state of the evaporation rate and the heat leakage, etc., so as to evaluate the performance of the cargo hold containment system. The cold cabin gas test alarm program processing module precisely controls the small flow injection of LNG by the LNG filling ship. The cargo hold of the LNG ship is quantitatively filled with LNG to keep the temperature in the cabin stable. The heat infiltrating value is equal to the latent heat of vaporization of the quantitatively filled LNG, measuring the generated BOG amount, comparing the measured evaporation rate (BOR) with the BOR design value of the LNG ship, judging whether it is within the set allowable range, judging whether the cold insulation function of the liquid cargo containment system in the cold cabin gas test is within the normal range, verifying the function of the LNG ship's containment system in the cold insulation stage of the cold cabin gas test operation. Therefore, there is no need to inject too much LNG, reducing the LNG consumption. The ultimate goal of this series of dynamic adjustments is to achieve the precise matching of the supply flow of the LNG filling ship and the internal heat load demand of the cargo hold, and then determine and maintain the optimal LNG filling rate and cumulative filling volume, realizing the economy of the cold cabin gas test operation.

[0080] During the temperature drop stage and the cold insulation stage, the cold cabin gas test alarm program processing module continuously evaluates the fault alarm level and the deviation of the LNG filling volume, records the filling volume duration and the timed filling volume. If the alarm level is normal or the LNG filling volume exceeds the allowable deviation range and the timed LNG filling volume is controllable, it is judged that the cold cabin gas test can continue; if the alarm level is abnormal, the duration is abnormal or the timed LNG filling volume is abnormal, the cold cabin gas test operation is suspended, and the fault analysis and evaluation information is fed back to the data module for recording and analysis, and remedial measures are taken in a timely manner.

[0081] In the cold cabin gas test, through the IAS system of the LNG ship, the status of the cargo containment system is statistically analyzed and the alarm status is checked. For the alarm status, the fault tree tool is used to analyze the alarm reasons of the cargo containment system in the cold cabin gas test, and suggestions for fault solution are provided. If the alarm that cannot be eliminated by taking normal measures is an abnormal alarm, different solutions are provided for different cold cabin gas test stages. Recalculate the LNG filling rate in each stage of the cold cabin gas test, recalculate the cold insulation filling time, optimize the cold cabin gas test operation measures, calculate the comparison between the actual cumulative injected LNG consumption value and the predicted LNG consumption value, etc., and record the historical data for reference and preservation in the data module.

[0082] If the data in the cold insulation stage continuously meets the preset safety standards, especially the hull cold point inspection is normal, it can be judged that the function of the cargo containment system is complete and reliable. After measuring that the temperature distribution of the hull surface structure is normal, the function evaluation of the LNG cargo hold containment system is completed, and the cold cabin gas test operation ends.

[0083] Safety objectives of the management system: Cargo hold pressure stability > Temperature drop gradient in the cargo hold > BOG economy. Economic objective: Under safety constraints, maximize the LNG filling rate and minimize the BOG emission. Through the information interaction between each module of the control system, key information such as the LNG filling rate and the maximum instantaneous BOG processing value can be adjusted in real time and accurately according to the status and stage of the cold cargo hold gas test operation, ensuring that the generated BOG volume is matched with the dual-ship BOG processing capacity, guaranteeing the economic and safety objectives of the cold cargo hold gas test operation, and simultaneously achieving intelligent monitoring of the cold cargo hold gas test.

[0084] In a specific implementation case, during the preparation stage of the cold cargo hold gas test operation: Connect the cargo holds of the LNG filling ship and the LNG ship through a co-phase pipeline to form a unified cold cargo hold gas test operation loop system. The management system connects the IAS systems of the two ships, and the data acquisition unit of the management system collects data information.

[0085] In the initial stage of the cold cargo hold gas test operation, check and confirm the boundary conditions of the cold cargo hold gas test operation, set the initial LNG filling rate, and predict the maximum LNG consumption.

[0086] During the cold cargo hold gas test operation stage, set the cold cargo hold gas test management model for the LNG ship to guide the cold cargo hold gas test process, and fill LNG while maintaining the stability of the cabin pressure.

[0087] The cold cargo hold gas test filling rate control module dynamically adjusts the LNG filling rate to ensure the stability of the temperature drop during the cold cargo hold gas test operation. The cold cargo hold gas test alarm program processing module completes the inspection of the LNG containment system and the insulation layer, as well as the control and inspection of the temperature gradient drop in the cabin.

[0088] During the cold cargo hold gas test operation, the cold cargo hold gas test heat balance calculation module calculates the generated BOG volume and the dual-ship combined BOG processing volume, controls the start-stop sequence of the dual-ship BOG processing equipment, maintains the stability of the cabin pressure in the cargo hold under the set temperature drop gradient, realizes the unified control of BOG for the two ships and the optimal LNG filling rate. The dual-ship combined BOG processing capacity sets a global target, and judges in real time whether the BOG growth rate is controllable. When the generated BOG volume exceeds the preset value, that is, when the BOG evaporation overflow rate percentage is greater than 1, the cold cargo hold gas test filling rate control module of the management system will automatically trigger an adjustment mechanism to reduce the LNG filling volume. The management system finds the optimal BOG generation volume according to the cold cargo hold gas test management model, ensures that the BOG generation volume matches the dual-ship combined BOG processing capacity, and ensures that the BOG is properly processed without the risk of overflow.

[0089] During the cold insulation stage, with no liquid LNG in the cargo hold, LNG is quantitatively filled to stabilize the hold temperature. The cold hold gas test alarm program processing module checks the safety data of the LNG ship and determines that the fault alarm level is normal. If the alarm level is normal, it is judged that the continuous cold hold gas test operation can be carried out. During a certain cold insulation time, if the inspected data, including the temperature data of the key cold points inside the ship's hull, is normal, the cold hold gas test alarm program processing module can determine that the enclosing system function is complete and reliable, complete the function evaluation of the LNG cargo hold enclosing system, and end the cold hold gas test operation. If the alarm level is abnormal, the duration is abnormal, or the amount of LNG filled regularly is abnormal, the cold hold gas test operation is suspended, and the fault analysis and evaluation information is fed back to the data module for recording.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. However, such modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for managing cold tank gas testing operations on an LNG carrier, characterized in that: The steps include: S1: Establishing a management system, utilizing the management system to connect the integrated automation system of the LNG bunkering vessel and the integrated automation system of the LNG ship, wherein the management system obtains data information of the LNG bunkering vessel and the LNG ship, and then the management system establishes a cold tank gas test management model based on the data information, and connects the cargo holds of the LNG bunkering vessel and the LNG ship through a pipeline; S2: The management system checks the boundary conditions of the cold tank gas test operation, and then sets the initial LNG filling rate and predicts the maximum LNG consumption; S3: The management system controls the LNG bunkering vessel to fill LNG into the cargo tank at the initial LNG bunkering rate and starts the cold tank gas test operation; S4: iteratively acquiring data information through the management system and dynamically adjusting the LNG filling rate during the cold tank gas trial operation to perform the cold tank gas trial operation on the LNG carrier; The management system measures the BOG generation during the cold tank gas test operation and analyzes whether BOG overflow will occur based on the combined BOG processing capacity of the two ships. The combined BOG processing capacity of the two ships is the amount of BOG processed per unit time by the BOG processing equipment of the two ships. If the answer is yes, the management system adjusts the LNG filling rate; If the answer is no, the management system maintains the LNG refueling rate unchanged.

2. The LNG carrier cold tank gas trial operation management method according to claim 1, characterized in that: The cold chamber gas test management model is: in, Indicates the LNG filling rate, represents the specific enthalpy of LNG, Indicates the amount of BOG discharged per unit time, represents the BOG specific enthalpy, represents the heat transfer coefficient of the enclosure system, represents the heat transfer area of the cargo hold, Indicates the cabin temperature. Indicates the ambient temperature, Indicates the gaseous BOG mass in the cabin, represents the specific heat capacity of gas at constant volume; represents the heat transfer loss of the cargo hold containment system, Indicates the cargo hold volume, represents the gas constant, Indicates the allowable pressure fluctuation range of the containment system. represents the initial filling rate, represents the proportional control coefficient, Indicates the combined BOG processing capacity of the two ships. Indicates time.

3. The LNG carrier cold tank gas trial operation management method according to claim 2, characterized in that: The boundary conditions include the temperature of the LNG injected by the LNG bunkering ship, confirmation of the BOG joint processing capacity of the two ships, measurement of the enthalpy value of the LNG ship's cargo hold in a hot state, determination of the temperature drop gradient, determination of the allowable pressure fluctuation range of the containment system, and determination of the ambient temperature.

4. The LNG carrier cold tank gas trial operation management method according to claim 3, characterized in that: S4 also includes the following steps: During the cold tank gas trial operation, the management system starts the dual-ship BOG processing equipment to process BOG generated by the cold tank gas trial operation, so as to maintain a stable cargo tank pressure of the LNG ship.

5. The LNG carrier cold tank gas trial operation management method according to claim 4, characterized in that: S4 also includes the following steps: When the LNG filling rate remains unchanged and the cargo hold gas test temperature reaches the set value, the cold tank gas test operation enters the cold preservation stage, which is maintained for the set time. At the same time, the management system checks the safety data of the LNG ship, including the temperature data of the LNG ship and the function data of the containment system, to determine whether there is any abnormality or failure. If no abnormality or failure occurs, it is determined that the cold tank gas test operation can be continued. After the cold preservation stage is maintained for the set time, the management system completes the evaluation of the containment system of the LNG ship, and the cold tank gas test operation is completed; If an abnormality or failure occurs, the management system suspends the cold chamber gas test operation and records the failure information.

6. The LNG carrier cold tank gas trial operation management method according to claim 5, characterized in that: During the cold preservation stage, no liquid LNG remains in the cargo hold of the LNG ship. After the cold preservation stage, the amount of LNG output by the LNG bunkering ship is less than the predicted maximum LNG consumption, and the management system completes the evaluation of the containment system of the LNG ship.

7. The LNG carrier cold tank gas trial operation management method according to claim 4, characterized in that: After the management system calculates the BOG generation amount during the cold chamber gas test operation, it also includes the following steps: The management system starts the BOG processing equipment of the two ships in sequence, and the starting order is the LNG bunkering ship and the fuel equipment of the LNG ship, the reliquefaction equipment of the LNG bunkering ship, the reliquefaction equipment of the LNG ship, the GCU equipment of the LNG bunkering ship, and the GCU equipment of the LNG ship; When both ships' BOG treatment equipment was fully activated, the BOG generation still exceeded 90% of the combined BOG treatment capacity of the two ships, indicating a BOG overflow risk. The LNG bunkering rate is adjusted until the BOG generation is less than 90% of the combined BOG treatment capacity of the two ships and all the BOG treatment equipment on the two ships are started, so as to achieve dynamic adjustment of the LNG bunkering rate.

8. An LNG ship cold tank gas test operation management system, characterized in that: The method for managing the cold tank gas test operation of an LNG ship according to any one of claims 1 to 7 is used to execute the method, wherein the management system comprises a cold tank gas test data module, a cold tank gas test heat balance calculation module, a cold tank gas test filling rate control module and a cold tank gas test alarm program processing module, which are connected by signals. The cold chamber gas test data module is used to obtain data information; The cold tank gas test heat balance calculation module is used to establish a cold tank gas test management model to calculate BOG generation and cargo hold pressure; The cold tank gas test filling rate control module is used to control the LNG filling rate; The cold chamber gas test alarm program processing module is used to detect whether a fault occurs in the containment system and to issue an alarm message.

9. The LNG ship cold tank gas trial operation management system according to claim 8, characterized in that: The cold tank gas test heat balance calculation module is connected to the dual-ship BOG processing equipment, which includes the fuel equipment of the LNG bunkering ship, the fuel equipment of the LNG ship, the reliquefaction equipment of the LNG bunkering ship, the reliquefaction equipment of the LNG ship, the GCU equipment of the LNG bunkering ship, and the GCU equipment of the LNG ship.

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