LNG (Liquefied Natural Gas) ship cold cabin gas test operation management method and management system

Abstract

The invention relates to the technical field of cold cabin gas test, in particular to an LNG ship cold cabin gas test operation management method and system, and the method comprises the steps: enabling an LNG filling ship and an integrated automation system of an LNG ship to be communicated through a management system, obtaining data information through the management system, and building a cold cabin gas test management model through the management system according to the data information; the management system checks boundary conditions of gas test operation of the cold cabin, and then the initial LNG filling rate is set and the maximum LNG consumption is predicted; the management system controls to start cold cabin gas test operation; and iterating the obtained data information through the management system and dynamically adjusting the LNG filling rate in the cold cabin gas test operation process so as to implement the cold cabin gas test operation of the LNG ship. The probability of accidental release accidents of the gaseous BOG is reduced, the alarm condition in the cold cabin gas test operation process is comprehensively mastered, and then the economical efficiency and safety of the LNG ship cold cabin gas test are guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of LNG ship cold tank gas testing, and in particular to a LNG ship cold tank gas testing operation management method and management system. Background Art

[0002] During the construction of LNG ships, the cold tank gas test process plays an important role in process verification. It ensures the quality of the cargo hold containment system by testing its low temperature resistance. Traditionally, the cold tank gas test of LNG ships needs to be carried out at the receiving station, but this process is accompanied by multiple risks. Due to the large volume and diverse types of LNG ship cargo holds, the generation of BOG (boil-off gas) is difficult to control, and 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 test cycle, but also leads to excessive filling and waste of LNG. In addition, the instability of BOG during the cold tank gas test can easily cause overflow, posing a challenge to the safety of LNG ships. Excessive LNG filling also means the need to return to the terminal for retransmission, 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 solve at least one of the technical problems existing in the related art. To this end, the present invention provides a management method and management system for cold tank gas testing of LNG ships, which solves the technical problems of difficult and high risk factors in the prior art of cold tank gas testing of LNG ships. The present application accurately adjusts the LNG filling amount according to the needs of the cold tank gas testing process, maintains the stable generation of BOG in the cabin, predictively handles the large-scale BOG generated by the cold tank gas testing and handles it in an orderly manner, reduces the probability of accidental release of gaseous BOG, and fully grasps the alarm conditions in the process, thereby ensuring the safety of the cold tank gas testing of LNG ships, realizing the cold tank gas testing of LNG ships without liquid LNG, saving the amount of injected LNG, and no need to return LNG to the LNG terminal, saving costs.

[0004] The present invention provides a method for managing cold tank gas testing operations of an LNG ship, comprising the following steps: S1: Establish a management system, and use the management system to connect the integrated automation system of the LNG bunkering ship and the integrated automation system of the LNG ship, the management system obtains data information of the LNG bunkering ship and the LNG ship, and then the management system establishes a cold tank gas test management model according to the data information, and connects the cargo tanks of the LNG bunkering ship and the LNG ship through pipelines; 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 ship to fill LNG into the cargo hold at the initial LNG bunkering rate and starts the cold tank gas test operation; 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.

[0005] A further improvement of the cold tank gas test operation management method of an LNG ship of the present invention is that the cold tank 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, is 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 handling capacity of the two ships. Indicates time.

[0006] A further improvement of the cold tank gas trial operation management method of an LNG ship of the present invention is that the boundary conditions include the temperature of LNG injected by the LNG bunkering ship, confirmation of the BOG joint processing capacity of the two ships, determination of the enthalpy value of the cargo hold of the LNG ship in the hot tank state, determination of the temperature drop gradient, determination of the pressure fluctuation range allowed by the containment system and determination of the ambient temperature, and the two-ship BOG joint processing capacity is the amount of BOG processed per unit time by the two-ship BOG processing equipment.

[0007] A further improvement of the LNG ship cold tank gas test operation management method of the present invention is that S4 further includes the following steps: The management system measures the BOG generation during the cold tank gas test operation and analyzes whether the BOG will overflow based on the BOG joint processing capacity 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 fueling rate unchanged.

[0008] A further improvement of the LNG ship cold tank gas test operation management method of the present invention is that S4 further includes the following steps: During the cold tank gas test operation, the management system starts the dual-ship BOG processing equipment to process the BOG generated by the cold tank gas test operation through the dual-ship BOG processing equipment to maintain the cargo tank pressure of the LNG ship stable.

[0009] A further improvement of the LNG ship cold tank gas test operation management method of the present invention is that S4 further includes the following steps: When the LNG filling rate remains unchanged and the gas test temperature of the cargo hold reaches the set value, the cold storage phase of the cold hold gas test operation is entered, and the set time of the cold storage phase is maintained. At the same time, the management system checks the safety data of the LNG ship, which includes the temperature data of the LNG ship and the function data of the containment system, to determine whether an abnormality or failure occurs; If no abnormality or failure occurs, it is determined that the cold tank gas test operation can be continued. After the cold preservation stage setting time is maintained, 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.

[0010] A further improvement of the cold tank gas trial operation management method of an LNG ship of the present invention is that during the cold preservation stage, no liquid LNG remains in the cargo hold of the LNG ship, and 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.

[0011] A further improvement of the LNG ship cold tank gas trial operation management method of the present invention is that after the management system measures the BOG generation amount during the cold tank gas trial 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 the BOG treatment equipment of both ships was fully started, the BOG generation still exceeded 90% of the combined BOG treatment capacity of the two ships, which means that the analysis showed that there would be a risk of BOG overflow; The LNG filling rate is adjusted until the BOG generation is less than 90% of the combined BOG processing capacity of the two ships and all the BOG processing equipment of the two ships are started, so as to achieve dynamic adjustment of the LNG filling rate.

[0012] 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 comprises a cold tank gas test data module, a cold tank gas test heat balance measurement 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 the 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 the containment system fails and to issue an alarm message.

[0013] A further improvement of the cold tank gas test operation management system of an LNG ship of the present invention is that the cold tank gas test heat balance measurement module is connected to the double-ship BOG processing equipment, and the double-ship BOG processing equipment 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.

[0014] The present invention realizes the unification of data acquisition and BOG control, so that the management of cold tank gas test operation realizes unified detection and management; it can quantitatively analyze the probability of BOG overflow in the cold tank gas test operation, and ensure the safety of the cargo containment system of the LNG ship; it realizes the precise control and dynamic adjustment of the filling of LNG in the cold tank gas test operation, and dynamically adjusts the filling rate and filling amount of LNG; in the LNG ship cargo hold temperature drop stage and cold preservation stage, it keeps the LNG ship free of liquid LNG, reduces the LNG consumption, and realizes the economy of cold tank gas test; if problems are found in the containment system inspection, the LNG cargo hold can be promptly repaired because the cabin is in a dry state. Supply measures can easily control risk points; the establishment of a dynamic model for cold tank gas testing can realize dynamic process control of cold tank gas testing, dynamically adjust the priority of control targets, prevent BOG overflow risks, automatically quantify and analyze overflow risks, and enhance the safety of cold tank gas testing operations; it can realize real-time, accurate and dynamic prediction and control of the filling volume of LNG bunkering ships and the BOG generated by cold tank gas testing, improve the efficiency of large-scale processing of cold tank BOG, and ensure the smooth and efficient cold tank gas testing process; it can realize intelligent auxiliary functions for LNG ship cold tank gas testing operations, including easily completing the verification of the functional integrity of the LNG ship containment system according to established procedures.

[0015] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 It is a block diagram of a method for managing cold tank gas testing operations of an LNG ship provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of 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.

[0019] Combine the following Figure 1 A method for managing cold tank gas testing of an LNG ship according to the present invention is described, comprising the following steps: S1: Establish a management system, use the management system to connect the integrated automation system of the LNG bunkering ship and the integrated automation system of the LNG ship, the management system obtains data information of the LNG bunkering ship 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 ship and the LNG ship through pipelines; 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 ship to fill LNG into the cargo hold at the initial LNG bunkering rate and starts the cold tank gas test operation; S4: Iterate the data information obtained through the management system and dynamically adjust the LNG filling rate during the cold tank gas trial operation to implement the cold tank gas trial operation of the LNG ship.

[0020] In a preferred implementation case of a method for managing cold tank gas testing of an LNG ship of the present invention, the cold tank gas testing management model is: in, Indicates the LNG filling rate in kg / s. Indicates the specific enthalpy of LNG in kJ / kg. Indicates the amount of BOG discharged per unit time, in kg / s. represents the specific enthalpy of BOG in kJ / kg. Indicates the heat transfer coefficient of the enclosure system, in W / m 2 K, Indicates the heat transfer area of ​​the cargo hold, in m 2 , Indicates the cabin temperature in K. Indicates the ambient temperature in K. Indicates the mass of gaseous BOG in the cabin, in kg. It represents the specific heat capacity of gas at constant volume, in kJ / kg·K; It represents the heat transfer loss of cargo hold containment system, in W. Indicates the cargo hold volume in m 3 , represents the gas constant, the unit is J / kg·K, Indicates the allowable pressure fluctuation range of the containment system, in Pa. Indicates the initial filling rate in kg / s. represents the proportional control coefficient, Indicates the combined BOG handling capacity of the two ships, in kg / s. Indicates time in seconds, where 1W=0.001kJ / s, 1J=1m 3 / Pa.

[0021] Specifically, the boundary conditions include the temperature of LNG injected by the LNG bunkering ship, confirmation of the dual-ship BOG joint processing capacity, determination of the enthalpy value of the cargo hold of the LNG ship in the 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 dual-ship BOG joint processing capacity is the amount of BOG processed by the dual-ship BOG processing equipment per unit time.

[0022] Furthermore, S4 also includes the following steps: the management system measures the BOG generation amount during the cold tank gas test operation, and analyzes whether BOG overflow will occur based on the BOG joint processing capacity 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 keeps the LNG filling rate unchanged, that is, the control system keeps the current control program unchanged.

[0023] Specifically, when the management system analyzes that BOG will not cause overflow risk and the cargo hold pressure remains stable, the LNG filling rate remains unchanged; when the LNG filling rate remains unchanged and the cargo hold gas test temperature reaches the set value, the cold hold gas test operation enters the cold preservation stage, and the cold preservation stage set time is maintained. At the same time, the management system checks the safety data of the LNG ship, which includes the temperature data of the LNG ship and the containment system function data, to determine whether there is an abnormality or fault; in the cold preservation stage, there is no excessive liquid LNG retained in the cargo hold of the LNG ship. After the cold preservation stage is over, 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; if no abnormality or fault occurs, it is determined that the cold hold gas test operation can be continued, and the cold preservation stage set time is maintained. The management system completes the evaluation of the containment system of the LNG ship, and the cold hold gas test operation ends; if an abnormality or fault occurs, the management system suspends the cold hold gas test operation and records the fault information.

[0024] Furthermore, 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 the BOG generated by the cold tank gas trial operation through the dual-ship BOG processing equipment to maintain the cargo hold pressure of the LNG ship stable.

[0025] Specifically, after the management system calculates the BOG generation amount during the cold chamber gas trial operation, it also includes the following steps: the management system sequentially starts the BOG processing equipment of the two ships, 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 the BOG processing equipment of the two ships are all started, the BOG generation amount still exceeds 90% of the combined BOG processing capacity of the two ships, that is, the risk of BOG overflow is analyzed; the LNG filling rate is adjusted until the BOG generation amount is less than 90% of the combined BOG processing capacity of the two ships and the BOG processing equipment of the two ships are all started, so as to realize dynamic adjustment of the LNG filling rate.

[0026] A cold tank gas test operation management system for an LNG ship is used to execute the above-mentioned cold tank gas test operation management method for an LNG ship. The management system comprises a cold tank gas test data module, a cold tank gas test heat balance measurement 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 tank gas test data module is used to obtain data information; the cold tank gas test heat balance measurement module is used to establish a cold tank gas test management model to measure the BOG generation amount and the cargo hold pressure; the cold tank gas test filling rate control module is used to control the LNG filling rate; the cold tank gas test alarm program processing module is used to detect whether a containment system fails and to issue an alarm message.

[0027] Furthermore, 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 (gas combustion unit) equipment of the LNG bunkering ship, and the GCU equipment of the LNG ship.

[0028] The management method and management system in the present application are used for functional verification of the LNG bunkering ship completing the cold tank gas trial operation for the LNG ship. Through the management system, they are fully connected with the integrated automation system (IAS) of the LNG bunkering ship and the LNG ship respectively, and can monitor and control the control system parameters of the two ships (LNG bunkering ship and LNG ship). The two ships are connected through process pipelines, that is, the liquid phase is connected to the liquid phase, and the gas phase is connected to the gas phase, so as to facilitate the cold tank gas trial operation.

[0029] The management system uses the existing integrated automation system (IAS) and boil-off (BOG) processing equipment of LNG bunkering ships and LNG ships. The system can accurately control the bunkering rate of LNG bunkering ships. Based on the real-time data of the cold tank, the management system jointly processes the generated BOG and optimizes the LNG injection amount during the cold tank gas test temperature drop and cold preservation process, maintains the LNG tank without liquid LNG, and achieves the minimum filling amount. At the same time, the functional detection and evaluation of the LNG ship containment system is completed. Through the linkage and real-time control of the dual-ship data, the cold tank gas test cycle is shortened, the risk of BOG overflow during the cold tank gas test is effectively prevented, and the safety and economy of the cold tank gas test operation process are improved to achieve energy saving and environmental protection.

[0030] The cold tank 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 bunkering ship and the LNG ship through the inter-ship jumper data line and communication protocol to collect data to obtain data information. The data information includes environmental information, cold tank gas test analysis information of the LNG ship cargo hold containment system and LNG bunkering ship bunkering information.

[0031] Specifically, the environmental information includes air and sea water temperature.

[0032] Specifically, the cold tank gas test function analysis information of the cargo hold containment system of the LNG ship includes the cargo hold type, capacity, design BOR value, cargo hold temperature of the LNG ship, gas pressure and density in the cargo hold of the LNG ship, LNG liquid level in the cargo hold of the LNG ship, insulation layer temperature of the cargo hold of the LNG ship, nitrogen pressure of the insulation layer, measured temperature of key cold spots in the hull and other data required by the LNG ship process manual, such as the safety alarm value of the cold tank gas test of the cargo hold containment system of the LNG ship.

[0033] Specifically, the LNG bunkering ship bunkering information includes data such as LNG bunkering temperature, flow rate, and amount of returned BOG to be processed.

[0034] The data storage and analysis unit compares the cargo hold characteristics according to the status information of the LNG tank type (for different LNG tank types: type C, type B and membrane type), tank capacity and containment system to find the LNG injection amount and cargo containment system temperature field model during the cold tank gas trial operation of the same cargo hold in the stored data, selects the temperature drop curve of the cold tank gas trial operation, and determines the LNG filling rate in the initial stage based on empirical rules, such as the initial filling rate does not exceed 30% of the design value, and predicts the maximum LNG consumption value of the cold tank gas trial operation. The information data and the initially selected LNG filling rate will be transmitted to the cold tank gas trial filling rate control module and the cold tank gas trial heat balance measurement module for processing.

[0035] The data storage and analysis unit is used for storing and analyzing data, including the temperature and pressure change data inside and outside the cargo hold during the cold tank gradient temperature drop stage and the continuous cold preservation stage, such as the data required by the LNG ship process manual and the cold tank gas test models of various cargo hold enclosure systems, such as the temperature, pressure and liquid cargo insulation layer temperature change data of the LNG ship.

[0036] The data storage and analysis unit stores and preprocesses the collected real-time cold chamber gas test operation data, conducts a comprehensive evaluation of the cold chamber gas test operation, and provides support for the detection and implementation of subsequent procedures.

[0037] The cold tank gas test heat balance calculation module first checks and confirms the boundary conditions of the cold tank gas test operation. The boundary conditions include: checking and determining the LNG temperature injected (output) by the LNG bunkering ship (such as -160±2°C); calculating and confirming the maximum capacity of the two ships to jointly process BOG; measuring the enthalpy value of the LNG ship in the hot tank state, and the temperature drop gradient of the cold tank is 10°-15°C; the cargo hold pressure fluctuation is ≤5% of the pressure setting value, and checking and measuring the temperature of the cold tank gas test environmental conditions.

[0038] After the cold tank gas test data module completes the selection of the temperature drop curve of the LNG ship cargo hold, the cold tank gas test heat balance calculation module establishes a cold tank gas test operation management model for the cargo hold type of the LNG ship (for LNG tanks of different materials and different insulation performance) based on the input operating condition data, cargo hold heat balance calculation equation, cargo hold insulation performance, thermal conductivity of the liquid cargo tank wall and bulkhead contact area, and predicts the LNG filling amount in the cold tank stage and the BOG generation amount of cold tank evaporation.

[0039] Based on the calculation of thermal enthalpy value and heat transfer value of cargo hold based on parameters such as temperature, volume, density and pressure of gaseous BOG in cargo hold, surface area in cargo hold and other parameters, a dynamic model of cold hold gas test of corresponding type 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.

[0040] Specifically, the cargo hold is adjusted to maintain no liquid LNG and the pressure in the cargo hold of the LNG ship is in a stable state (the overflowing BOG is handled by the double-ship BOG processing equipment according to the procedure). The filling rate control module dynamically adjusts the filling rate based on the heat balance calculation results to maintain the stable pressure of the LNG cargo hold and avoid excessive liquid LNG retention.

[0041] The cold tank gas test heat balance calculation module uses FLUENT advanced simulation software to numerically simulate the thermal environment of the cargo hold of the LNG ship during the cold tank process, verify the amount of BOG generated, correct the LNG filling amount of the cold tank gas test, and provide real-time feedback to the filling rate control module. The cumulative filling amount and the timed filling amount are compared with the real-time BOG generation of the LNG ship cold tank gas test to verify the performance of the LNG ship cargo hold.

[0042] The cold tank gas test heat balance calculation module evaluates the dynamic relationship between the LNG bunkering ship injection rate and the BOG amount generated during the cold tank process in the hot tank state of the LNG ship, and calculates the dynamic BOG processing capacity and corrects the BOG prediction value after the dual ship process is connected.

[0043] The cold tank gas test filling rate control module adjusts the LNG injection rate of the bunkering ship by sending flow control instructions to the LNG bunkering ship, controls the temperature drop gradient of the cold tank; and controls the start and stop of the dual-ship joint BOG processing equipment to keep the LNG ship cargo hold in a stable pressure state.

[0044] According to the predicted maximum BOG generation value of the LNG ship, the total BOG processing capacity of the two ships is compared. When the predicted BOG generated by the cold chamber gas test is less than the BOG processing capacity of the two ships, the BOG processing equipment of the two ships is started in sequence to process the BOG generated in the cold chamber until the BOG generated in the cold chamber is completely processed. The management system counts the number of started BOG processing equipment and the real-time total BOG processing volume, predicts the LNG bunkering volume, and feeds back the output results.

[0045] When the combined BOG processing capacity of the two ships is fully activated and is still less than the predicted BOG emission value generated in the cold tank, it is ensured that the generated BOG emission does not exceed 90% of the combined BOG processing capacity of the two ships, that is, a BOG overflow risk is generated (the BOG overflow risk is defined as greater than the set value 1, BOG overflow risk = maximum BOG generation value of the LNG ship cold tank gas test operation / combined BOG processing capacity of the two ships). The LNG injection rate is updated using the cold tank gas test dynamic model to find the optimal BOG generation, and the control signal is transmitted to the cold tank gas test filling rate control module and the cold tank gas test alarm program processing module for processing. Under the set LNG cargo tank temperature drop gradient, the LNG filling amount is accurately controlled to ensure that the BOG generation amount matches the combined BOG processing capacity of the two ships, so as to realize dynamic adjustment of the LNG filling rate and filling amount.

[0046] The cold tank gas test filling rate control module communicates with the LNG bunkering ship's IAS system in real time to adjust and accurately control the filling rate of the LNG bunkering ship, and compares the predicted LNG consumption value with the actual LNG filling value. During the cold tank gas test of the LNG ship cargo hold, the LNG ship cargo hold is always kept in a dry state without liquid LNG through the detection and control of the management system until the functional verification of the LNG ship cold tank gas test is completed, and there is no need for the LNG ship to return too much LNG to the LNG bunkering ship. The most economical cold tank gas test operation is achieved to save the amount of LNG injected. If the cargo hold containment system fails, replenishment measures can be taken in time for the LNG cargo hold because the cabin is in a dry state, which makes it easy to control risk points.

[0047] The cold tank gas test alarm program processing module, after receiving the information from the above modules, checks the BOG overflow risk during the cold tank gas test of the LNG bunkering ship and the alarm status of the LNG ship's cargo containment system during the cold tank gas test, including detecting the temperature changes of the cargo hold and the containment system including the insulation layer, and evaluating the safety status of the cold tank gas test process. If the BOG overflow risk exceeds the set value 1, the system automatically sends out a warning signal to reduce the amount of LNG injected. When a critical alarm occurs during the alarm status check of the LNG ship's cargo containment system, the management system automatically sends out an alarm signal, applies to terminate the cold tank gas test operation, and checks the cause. The LNG ship gas test alarm program processing module sets a global target for BOG processing capacity, determines whether the BOG growth rate is controllable, evaluates and analyzes the probability of BOG overflow risk during the cold tank gas test, quantitatively analyzes the BOG generation data, compares it with the BOG processing equipment capacity, and calculates the BOG overflow risk.

[0048] When the BOG overflow risk is greater than 1, it means that the probability of BOG overflow risk is high. At the same time, the cargo tank pressure of the LNG ship is monitored to determine whether the liquid cargo tank status is normal, and the impact of BOG generation on the tank pressure is evaluated. When the tank pressure is high and an alarm is generated, an alarm signal is output, thereby realizing the safe management of the cold tank gas test of the LNG bunkering ship.

[0049] The cold tank gas test alarm program processing model will refer to the process design value and conduct safety alarm checks on the cold tank gas test operations. When the duration of the real-time unit cold tank 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 the cargo hold containment system monitors key data alarms, the system automatically issues a warning signal. The LNG ship gas test alarm program processing module can conduct accurate safety assessment and quantitative analysis of the LNG ship cold tank gas test operations to ensure the safety of the LNG ship cargo containment system during the cold tank gas test operations.

[0050] When the duration of the real-time unit cold tank 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 occurs during the alarm status check of the LNG ship cargo containment system, LNG injection continues and LNG tank cold tank operations can continue.

[0051] When the cargo hold cold tank gas test temperature reaches the set value (such as reaching -130° to -140° and maintaining it for a certain period of time), the LNG in the hold enters the cold preservation stage. The LNG ship gas test alarm program processing module analyzes the temperature field distribution status in the LNG hold, including the data check of the insulation layer temperature, and checks the data against the data module design data to determine whether the cargo containment system function is within the normal range; assuming that the heat penetrating into the cargo hold environment of the LNG ship containment system is constant, the evaporation rate and the heat leakage balance state are calculated, etc., so as to evaluate the performance of the cargo hold containment system. The LNG ship gas test alarm program processing module precisely controls the LNG bunkering ship to inject LNG at a small flow rate. The LNG ship cargo hold is quantitatively filled with LNG, the temperature in the hold is kept stable, the infiltration heat value is equal to the latent heat of gasification of the quantitatively added LNG, the amount of BOG generated is measured, and the measured evaporation rate (BOR) is compared with the BOR design value of the LNG ship to determine whether it is within the set allowable range, and whether the cold preservation function of the liquid cargo containment system of the cold tank gas test is within the normal range. The function of the LNG ship containment system during the cold preservation stage of the cold tank gas test operation is verified, so there is no need to inject too much LNG, reducing the amount of LNG used. The ultimate goal of this series of dynamic adjustments is to achieve a precise match between the supply flow of the LNG bunkering ship and the heat load demand inside the cargo hold, and then determine and maintain the optimal LNG filling rate and cumulative filling amount, and achieve the economy of the cold tank gas test operation.

[0052] During the temperature drop stage and the cold storage stage, the cold chamber gas test alarm program processing module continuously evaluates the fault alarm level and the LNG filling quantity deviation, records the filling duration and the scheduled filling quantity. If the alarm level is normal or the LNG filling quantity exceeds the allowable deviation range, the scheduled LNG filling quantity is controllable, and it is determined that the cold chamber gas test can be continued. If the alarm level is abnormal, the duration is abnormal, or the scheduled LNG filling quantity is abnormal, the cold chamber 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.

[0053] During the cold tank gas test, the cargo containment system status is counted and the alarm status is checked through the LNG ship IAS system. For the alarm status, the fault tree tool is used to analyze the alarm cause of the cold tank gas test cargo containment system, and fault resolution suggestions are provided. If the alarm cannot be eliminated by normal measures, it is an abnormal alarm, and different solutions are provided for different cold tank gas test stages. Recalculate the LNG filling rate at each stage of the cold tank gas test, recalculate the cold storage filling time, optimize the cold tank gas test operation measures, calculate the actual cumulative injection LNG consumption value and compare it with the predicted LNG consumption value, etc., and record it into the data module as a reference for historical data preservation.

[0054] The data during the cold preservation stage continued to meet the preset safety standards, especially the normal inspection of the hull cold spots, which showed that the cargo containment system was fully and reliably functional. After determining that the temperature distribution of the hull surface structure was normal, the functional evaluation of the LNG cargo hold containment system was completed and the cold hold gas test operation was completed.

[0055] Safety objectives of the management system: stable cargo hold pressure > cargo hold temperature drop gradient > BOG economy; economic objectives: maximize the LNG filling rate and minimize BOG emissions under safety constraints. Through information interaction between the various modules of the control system, the LNG filling rate and BOG instantaneous processing maximum value and other key information can be accurately adjusted in real time according to the status and stage of the cold chamber gas test operation to ensure that the BOG generation is controlled to match the BOG processing capacity of the two ships, to ensure the economic and safety objectives of the cold chamber gas test operation, and to achieve intelligent monitoring of the cold chamber gas test.

[0056] In a specific implementation case, during the cold tank gas test operation preparation stage: the LNG bunkering ship and the cargo hold of the LNG ship are connected through the same-phase pipeline to form a unified cold tank gas test operation loop system, the management system is connected to the IAS systems of the two ships, and the data acquisition unit of the management system collects data information; At the initial stage of the cold tank gas test operation, the boundary conditions of the cold tank gas test operation are checked and confirmed, the initial LNG filling rate is set, and the maximum LNG consumption is predicted; During the cold tank gas test operation, the cold tank gas test management model of the LNG carrier is set to guide the cold tank gas test process and to fill LNG while maintaining stable tank pressure; The cold tank gas test filling rate control module dynamically adjusts the LNG filling rate to ensure the temperature drop stability of the cold tank gas test operation. The cold tank gas test alarm program processing module completes the inspection of the LNG containment system and insulation layer, as well as the control and inspection of the temperature gradient drop in the cabin; During the cold tank gas test operation, the cold tank gas test heat balance calculation module calculates the BOG generation and the two-ship joint BOG processing volume, controls the start and stop sequence of the two-ship BOG processing equipment, maintains the stability of the cargo hold pressure under the set temperature drop gradient, realizes the unified BOG control and the optimal LNG filling rate of the two ships, sets the global target for the two-ship joint BOG processing capacity, and judges in real time whether the BOG growth rate is controllable. When the BOG generation exceeds the preset value, that is, the BOG evaporation overflow rate percentage is greater than 1, the cold tank gas test filling rate control module of the management system will automatically trigger the adjustment mechanism to reduce the LNG filling volume. The management system finds the optimal BOG generation according to the cold tank gas test management model to ensure that the BOG generation matches the two-ship joint BOG processing capacity and that the BOG is properly handled without overflow risk. During the cold storage stage, while keeping the cargo hold free of liquid LNG, quantitative LNG is added 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, the cold hold gas test operation is determined to be sustainable. The inspection data within a certain cold storage time, including the temperature data of key cold spots in the hull, are normal. The cold hold gas test alarm program processing module can determine that the containment system functions are complete and reliable, complete the LNG cargo hold containment system function evaluation, and end the cold hold gas test operation. If the alarm level is abnormal, the duration is abnormal, or the timed LNG filling amount 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.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions 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 ship, characterized in that: The steps include: S1: Establish a management system, and use the management system to connect the integrated automation system of the LNG bunkering ship and the integrated automation system of the LNG ship, the management system obtains data information of the LNG bunkering ship and the LNG ship, and then the management system establishes a cold tank gas test management model according to the data information, and connects the cargo tanks of the LNG bunkering ship and the LNG ship through pipelines; 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 ship to fill LNG into the cargo hold at the initial LNG bunkering rate and starts the cold tank gas test operation; 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.

2. The method for managing cold tank gas testing of an LNG ship 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, is 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 handling capacity of the two ships. Indicates time.

3. A method for managing cold tank gas testing of an LNG ship according to claim 2, characterized in that: The boundary conditions include the temperature of LNG injected by the LNG bunkering ship, confirmation of the dual-ship BOG joint processing capacity, determination of the enthalpy value of the cargo hold of the LNG ship in the 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. The dual-ship BOG joint processing capacity is the amount of BOG processed by the dual-ship BOG processing equipment per unit time.

4. A method for managing cold tank gas testing of an LNG ship according to claim 3, characterized in that: S4 also includes the following steps: The management system measures the BOG generation during the cold tank gas test operation and analyzes whether the BOG will overflow based on the BOG joint processing capacity 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 fueling rate unchanged.

5. A method for managing cold tank gas testing of an LNG ship according to claim 4, characterized in that: S4 also includes the following steps: During the cold tank gas test operation, the management system starts the dual-ship BOG processing equipment to process the BOG generated by the cold tank gas test operation through the dual-ship BOG processing equipment to maintain the cargo tank pressure of the LNG ship stable.

6. A method for managing cold tank gas testing of an LNG ship according to claim 5, characterized in that: S4 also includes the following steps: When the LNG filling rate remains unchanged and the gas test temperature of the cargo hold reaches the set value, the cold storage phase of the cold hold gas test operation is entered, and the set time of the cold storage phase is maintained. At the same time, the management system checks the safety data of the LNG ship, which includes the temperature data of the LNG ship and the function data of the containment system, to determine whether an abnormality or failure occurs; If no abnormality or failure occurs, it is determined that the cold tank gas test operation can be continued. After the cold preservation stage setting time is maintained, 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.

7. A method for managing cold tank gas testing of an LNG ship according to claim 6, 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.

8. The method for managing cold tank gas testing of an LNG ship according to claim 5, 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 the BOG treatment equipment of both ships was fully started, the BOG generation still exceeded 90% of the combined BOG treatment capacity of the two ships, which means that the analysis showed that there would be a risk of BOG overflow; The LNG filling rate is adjusted until the BOG generation is less than 90% of the combined BOG processing capacity of the two ships and all the BOG processing equipment of the two ships are started, so as to achieve dynamic adjustment of the LNG filling rate.

9. 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 8 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 the 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 the containment system fails and to issue an alarm message.

10. The LNG ship cold tank gas test operation management system according to claim 9, 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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