Method for merging and matching gas test items of LNG transport ship

Abstract

The invention discloses a method for merging and matching gas test items of an LNG transport ship. The method comprises the following steps: synchronously carrying out a self-flow gas supply mode large-flow combustion test of a GCU at the cold cabin last stage of a first cold cargo cabin; after the cold cabin last phase of the first cold cargo cabin is finished, a GMS (Gas Management System) controls the GCU flow test process to be synchronously carried out; the forced vaporizer maximum flow function debugging and the compressor air supply mode endurance test of the GCU are synchronously carried out; the energy consumption test of a host under different navigational speeds and different powers in an unmanned cabin project in a cabin gas mode and the GMS automatic control forced vaporizer flow test are synchronously carried out; and the LNG ship cargo hold temperature rise process and the ship speed measurement process are synchronously carried out. According to the system and the method, the test time, the test cost and the carbon emission can be reduced, the stability and the safety of a gas system are improved, the operation efficiency of the LNG transport ship can be improved, and contribution can be made to global environmental protection career.

Description

Technical Field

[0001] The present invention relates to the technical field of gas sea trials for LNG carriers, and in particular to a method for combining and matching gas test items for LNG carriers. Background Art

[0002] During the operation of liquefied natural gas (LNG) carriers, the performance and safety of the gas system are of vital importance. Therefore, during the gas trial phase of LNG carriers, in order to verify the operating conditions and performance of the ship's gas system and equipment in gas mode and ensure the normal operation of the ship's gas system and equipment in gas mode, a series of gas test items need to be carried out. These tests are intended to verify the working status, performance and safety of each component of the system in gas mode. However, in existing technologies, these test items are usually carried out separately. This means that in order to complete all the tests, a lot of time and natural gas are required to reach different gas system test conditions, which not only increases the test time, but also increases the cost of the test. Such a separate approach to conducting each sub-test is more likely to have an impact on the future operation of the ship. Since the tests conducted during the gas trial are mostly extreme conditions of equipment or systems, multiple starts and stops may affect the stability and life of the ship, and the parameters of the gas system need to be adjusted multiple times, which also increases the complexity of operation and the possibility of human error. Moreover, the existing practice will lead to additional carbon emissions, which runs counter to the current global focus on environmental protection.

[0003] Therefore, in order to solve the above problems, a method that can merge and optimize these test items is needed. The new method should be able to reduce test time, reduce test costs, reduce carbon emissions, and improve the stability and safety of the gas system. This can not only improve the operational efficiency of LNG carriers, but also contribute to global environmental protection. Summary of the invention

[0004] In view of this, the present invention provides a method for merging and matching gas test items of LNG carriers, so as to solve the problems existing in the above-mentioned background technology.

[0005] A method for merging and matching gas test items for LNG carriers, comprising the following steps:

[0006] S1, cooling down the cargo hold of the LNG carrier at the dock, and simultaneously conducting a large-flow combustion test of the GCU in the gravity air supply mode at the end of the first cold cargo hold;

[0007] S2, after the end of the cold hold period of the first cold hold, the process of the GCU flow test controlled by the gas management system (GMS) is carried out synchronously;

[0008] S3, at the wharf or after the ship is berthed at the gas station, debug the maximum flow function of the forced vaporizer outside the cargo hold, and simultaneously carry out the compressor supply mode durability test of the gas combustion unit (GCU);

[0009] S4, while the ship is berthed at the gas station, the energy consumption test of the main engine at different speeds in the engine room gas mode unmanned cabin project and the gas management system (GMS) automatic control forced carburetor flow test are carried out simultaneously;

[0010] The main engine power increase and decrease test in the unmanned cabin project in the cabin gas mode is carried out simultaneously with the gas management system (GMS) automatic control forced carburetor flow test;

[0011] S5, synchronize the LNG cargo hold heating process with the ship speed measurement process to save time loss during the sea hold warming period.

[0012] Preferably, the specific steps of step S1 are:

[0013] First, the cargo holds of LNG carriers are cooled at the dock;

[0014] When the cooling operation of the first refrigerated cargo hold is about to reach the end of the refrigeration period, the volatile gas main pipe of the first refrigerated cargo hold is separated from other cargo holds by valves, and the volatile gas pipe of the first refrigerated cargo hold is connected to the air inlet of the gas combustion unit (GCU) through a high-load heater;

[0015] When the first refrigerated cargo hold reaches the end of the cold period, the amount of natural gas replacement between the first refrigerated cargo hold and the non-first refrigerated cargo hold is reduced, and the volatile gas formed in the first refrigerated cargo hold is supplied to the GCU through the volatile gas pipe, and a large-flow combustion test of the GCU's gravity air supply mode is carried out simultaneously.

[0016] Preferably, at the end of the cold-hold period of the first cold-hold, when the cabin pressure in the first cold-hold reaches a high cabin pressure range of 15KPa-25KPa, a large-flow combustion test of the GCU in the gravity air supply mode is carried out simultaneously.

[0017] Preferably, in step S2, after the 21st hour of the first refrigerated cargo hold, the subsequent cargo hold cooling process and the GMS control GCU flow test process are carried out synchronously. At this stage, the volatile gas formed in the first refrigerated cargo hold can be completely consumed by GCU combustion, and the natural gas replacement gas path between the first refrigerated cargo hold and the non-first refrigerated cargo hold needs to be cut off.

[0018] Preferably, when the debugging of the maximum flow function of the forced vaporizer and the endurance test of the compressor air supply mode of the GCU are carried out simultaneously in step S3, the liquid supply pressure setting value of the gas pump in the cargo hold should not be lower than the outlet pressure setting value of the LD compressor in the GCU. When the forced vaporizer flow is increased to more than 50%, the liquid supply pressure of the gas pump can be gradually set to 130% of the outlet flow of the LD compressor but not higher than the trip setting value of the gas pipe safety valve to ensure the increase of the forced vaporizer outlet flow.

[0019] Preferably, when debugging the maximum flow function of the forced vaporizer in step S3 and performing the endurance test of the compressor air supply mode of the GCU simultaneously, the flow setting of the LD compressor air supply mode in the GCU must always be kept 5-8% higher than the outlet flow of the forced vaporizer, so as to ensure that the outlet flow of the forced vaporizer can always be consumed by the GCU and steadily increased when the main engine of the ship is not running, and the cargo hold pressure is always kept rising within a controllable range during this stage of the test.

[0020] Preferably, in step S3, when the maximum flow rate function of the forced vaporizer is debugged and the endurance test of the compressor air supply mode of the GCU is performed simultaneously, after the GCU reaches the maximum flow rate in the LD compressor air supply mode, the maximum combustion flow rate of the GCU is maintained and the OPV valve of the air supply network is opened manually step by step, and the outlet flow rate of the forced vaporizer continues to be gradually increased after each opening of the OPV valve;

[0021] During the process of gradually opening the OPV valve of the gas supply network, continue to pay attention to the condensate amount of the forced vaporizer and the LD heater in the GCU. If the condensate increase of the forced vaporizer and the LD heater in the GCU is too high in a short period of time, the outlet flow of the forced vaporizer should be gradually reduced to keep the condensate amount controllable. Through this process, the maximum flow of the forced vaporizer can be achieved. When the maximum flow test of the forced vaporizer is completed, the various flow test conditions of the GCU in the LD compressor gas supply mode are also matched and completed, and there is no need to consume natural gas specifically for the endurance test of the GCU compressor gas supply mode.

[0022] Preferably, in the process of gradually opening the OPV valve of the gas supply network, the OPV valve is opened by 1% each time to maintain stable pressure in the gas supply pipeline in the gas supply network and stable combustion of the GCU. After each opening of the OPV valve, the outlet flow of the forced vaporizer can continue to be gradually increased within 3%, and the OPV valve can be opened again after the pipeline pressure of the gas supply network is stable.

[0023] Preferably, in step S4, when the energy consumption test of the main engine at different speeds in the unmanned cabin project in the cabin gas mode and the forced vaporizer flow test automatically controlled by the gas management system (GMS) are carried out simultaneously, the 100% flow of the GCU is set as the rated maximum gas consumption of the main engine, and the actual gas consumption of the main engine at different speeds is simulated by increasing the gas flow of the GCU. The GCU transmits its gas flow to the ship's automatic control system (IAS) in real time, and the GMS automatically adjusts the outlet flow of the forced vaporizer according to the change of the tank pressure in the liquid cargo tank, and also adjusts the outlet flow of the gas pump synchronously;

[0024] When the main engine power increase and decrease test in the unmanned cabin project under the engine room gas mode is carried out simultaneously with the gas management system (GMS) automatic control forced vaporizer flow test, the 100% flow of the GCU is set as the rated maximum gas consumption of the main engine, and the actual gas consumption of the main engine under different powers is simulated by increasing the GCU gas flow. The GCU transmits its gas flow to the ship's automatic control system (IAS) in real time. The GMS automatically adjusts the outlet flow of the forced vaporizer according to the changes in the tank pressure in the liquid cargo tank, and also adjusts the outlet flow of the gas pump synchronously;

[0025] During the execution of this step, only the fuel gas pump of the cargo tank with liquid is in operation, and the other non-cargo tanks are warmed up after the cargo tank with liquid is partially unloaded to the gas station.

[0026] Preferably, when the LNG ship cargo tank heating process and the ship speed measurement process are carried out simultaneously in step S5, the non-cargo tank must have completed the first stage of warm-up operation with a large expansion amount, and when the cargo tank warm-up operation is carried out, the expansion amount of the cargo tank is slowly absorbed by the GCU and the non-cargo tank, which greatly shortens the discharge time of the vent mast and enables a large number of non-explosion-proof equipment required during the speed measurement test to be used safely.

[0027] The beneficial effects of the present invention are:

[0028] 1. The present invention matches the "GCU gravity air supply mode large flow combustion test" with the cold compartment end stage of the first cold compartment. In this stage, the direct gas replacement amount between the first cold compartment and the non-first cold compartment is gradually reduced to supply the volatile gas to the GCU for the gravity air supply mode large flow combustion test, which will just cause the pressure of the first cold compartment to rise, thereby gradually reducing the volatilization amount of LNG loaded after the cold compartment and reducing the loss.

[0029] 2. After the cold storage period of the first cold storage tank ends, the present invention simultaneously carries out the "gas management system (GMS) controlled GCU flow test", and the volatile gas volume in the cargo tank can be effectively covered by the GCU combustion gas flow, which can not only improve the accuracy and reliability of the gas test, but also realize the GCU flow test as early as possible, so that the security equipment can reach the available state in advance, and also reduce the various operational safety hazards after the LNG ship is cooled.

[0030] 3. The present invention simultaneously carries out "debugging the maximum flow function of the forced vaporizer" and "durability test of the compressor air supply mode of the gas combustion unit (GCU)". When completing the maximum flow test of the forced vaporizer, various flow test conditions of the GCU in the LD compressor air supply mode are also matched and completed, and there is no need to consume natural gas specifically for the latter test process.

[0031] 4. The present invention simultaneously carries out the "energy consumption test of the main engine at different speeds and powers" and the "gas management system (GMS) automatic control forced vaporizer flow test" in the unmanned cabin project in the engine room gas mode. Even when the LNG ship is berthed at the gas station and the main engine is not actually running, the actual consumption of the main engine at different speeds and powers can be accurately simulated through the GCU combustion consumption.

[0032] 5. The present invention synchronizes the cargo tank heating process of the LNG ship with the ship speed measurement process. At this time, the non-liquid cargo tank needs to have completed the first stage of warm-up operation with a large expansion amount. When the liquid cargo tank is warmed up, the expansion amount of the liquid cargo tank will be slowly absorbed by the GCU and the non-liquid cargo tank. Therefore, the cargo tank pressure will no longer increase sharply, which can greatly shorten the discharge time of the vent mast, so that a large number of non-explosion-proof equipment required during the speed measurement test can be used safely, and the time loss during the warm-up period at sea can also be saved.

[0033] 6. The present invention can reduce test time, test costs, carbon emissions, and improve the stability and safety of the gas system. It can not only improve the operating efficiency of LNG carriers, but also contribute to global environmental protection. The present invention has been tested during the gas trials of 6 LNG carriers, with strong feasibility and repeatability. It is a necessary and new method for the development of the industry, providing more efficient and environmentally friendly technical support for the trial trials and post-delivery operations of LNG carriers.

[0034] According to the average analysis of the test results of 6 LNG ships that have been completed, the implementation effect of this method has greatly reduced the test medium loss. Each LNG ship can save 493m3 of LNG consumption, which is equivalent to: 493*0.44*6500 (yuan / ton) / 10000=1.41 million yuan;

[0035] Each LNG ship can save one day of gas station window and save 1 million yuan in gas station service fees;

[0036] Since this implementation plan innovatively implemented a large number of new measures for LNG ship gas trials through independent research and actual ship verification, the relevant technical achievements are all independently controllable. Compared with the cost of outsourced experts to assist in the trial, each ship can save outsourcing costs: 1450 (Euro / person*day)*7.5 (exchange rate)*7 (number of people)*16 (number of days saved) / 10000=1.22 million yuan;

[0037] Based on the calculation that the applicant's company completes 7 LNG ship gas trial missions each year, the company can save a total of: (122+100+141)*7=25.41 million yuan each year. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only 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.

[0039] Figure 1 To match the large-flow combustion test of the gravity air supply mode of the gas combustion device with the process of cargo hold cooling down simultaneously.

[0040] Figure 2 It is a process of synchronizing the cargo hold cooling process with the GMS controlling the GCU flow test process in the present invention.

[0041] Figure 3 This is the operation process of the gas pump during the commissioning of the forced vaporizer in the present invention.

[0042] Figure 4 This is the process of carrying out speed measurement test during the warm-up period in the present invention.

[0043] Figure 5 Flow chart of the method of the present invention. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is described below by the specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0045] The terms used in this disclosure are for the purpose of describing specific embodiments only and are not intended to limit the disclosure. The singular forms of "a", "said" and "the" used in this disclosure and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0046] In order to better understand the technical solution of the present invention, the present invention is described in detail below with reference to the accompanying drawings.

[0047] The present invention provides a method for merging and matching gas test items of LNG carriers, which specifically comprises the following steps:

[0048] S1, the cargo hold of the LNG carrier is cooled down at the dock, and a large flow combustion test of the gas combustion unit (i.e., Gas Combustion Unit, GCU) in the self-flow gas supply mode (i.e., free flow mode) is simultaneously carried out at the end of the cold-hold of the first cold-hold.

[0049] Specifically, first, the cargo hold of the LNG carrier is cooled at the dock. In this embodiment, 1-2 tank trucks loaded with liquid LNG are used to refuel the cargo hold of the LNG carrier at the dock to cool the cargo hold.

[0050] When the cooling operation of the first refrigerated cargo hold is about to reach the end of the refrigeration period, the vapor header of the first refrigerated cargo hold is separated from other cargo holds by valves, and the vapor pipe of the first refrigerated cargo hold is connected to the air inlet of the gas combustion unit (GCU) through a high load heater (HDHeater);

[0051] When the first refrigerated cargo hold reaches the end of the cold period, the amount of natural gas replacement between the first refrigerated cargo hold and the non-first refrigerated cargo hold is reduced, and the volatile gas formed in the first refrigerated cargo hold is supplied to the GCU through the volatile gas pipe, and a large-flow combustion test of the GCU's gravity air supply mode is carried out simultaneously.

[0052] The first-cooled cargo hold refers to the first cargo hold to be cooled, and the cargo hold with the smallest capacity among all the cargo holds is used as the first-cooled cargo hold; the end of the cooling period of the first-cooled cargo hold refers to the period between the 10th and 21st hours of the cooling period of the first-cooled cargo hold, before which the volatile gas formed in the first-cooled cargo hold is supplied to the top of the non-first-cooled cargo hold through the volatile gas header via the high-load heater as the gas source for natural gas replacement, and when the first-cooled cargo hold enters the end of the cooling period, the amount of natural gas replacement between the first-cooled cargo hold and the non-first-cooled cargo hold is gradually reduced, and the volatile gas formed in the first-cooled cargo hold is supplied to the GCU through the volatile gas pipe, and the volatile gas formed in the first-cooled cargo hold is used as the fuel of the GCU to carry out a large-flow combustion test in the gravity gas supply mode of the GCU; in this embodiment, the outlet temperature of the high-load heater is preferably controlled at 25-30 degrees Celsius.

[0053] The GCU gravity gas supply mode large flow combustion test is carried out between the 10th and 21st hours of cooling the first refrigerated cargo hold to ensure that the spray consumption of the refrigerated cargo hold in the first 10 hours of rated refrigerated cargo hold time is within the theoretical range. After that, the gas flow rate used for gas replacement is reduced to carry out the GCU gravity gas supply test, which will just cause the pressure of the first refrigerated cargo hold to rise, thereby gradually reducing the volatilization of LNG loaded behind the refrigerated cargo hold and reducing losses. After the above operation, the working conditions of the next step can be matched.

[0054] During the GCU gravity air supply mode large flow combustion test, a higher cabin pressure is required to achieve stable combustion, which corresponds to the situation that the volatility of the first refrigerated cargo hold is gradually reduced. Therefore, the test at this stage is carried out at a higher cabin pressure to ensure the stable operation of the GCU test. Preferably, at the end of the cold cabin of the first refrigerated cargo hold, when the cabin pressure in the first refrigerated cargo hold reaches a high cabin pressure range of 15KPa-25KPa, the GCU gravity air supply mode large flow combustion test is carried out simultaneously.

[0055] S2, after the end of the cold hold period of the first cold hold (i.e. after the 21st hour of the cold hold period of the first cold hold), the gas management system (GMS) controls the process of the GCU flow test to be carried out synchronously.

[0056] After the 21st hour of the first refrigerated cargo hold being cooled, the first refrigerated cargo hold continues to be lowered, and during this process the "process of the gas management system (GMS) controlling the GCU flow test" is carried out simultaneously.

[0057] During the GMS controlled GCU flow test, the heat exchange between the cargo hold and the cargo hold insulation layer has gradually tended to a low and stable level. At this stage, the heat exchange between the main and secondary insulation layers of the liquid cargo tank and the tank is mainly used to evaporate the liquid LNG in the tank. Therefore, the volatile gas naturally volatilized by heat exchange in the first refrigerated cargo hold at this stage can be completely consumed by GCU combustion. In this case, the natural gas replacement gas path between the first refrigerated cargo hold and the non-first refrigerated cargo hold can be safely cut off to meet the prerequisite requirements of the "GMS controlled GCU flow test" and improve the accuracy and reliability of the gas test, and realize the GCU test as soon as possible, so that the security equipment can reach a usable state in advance, reducing the various safety hazards of operations after the LNG ship's refrigerated tank.

[0058] S3, at the dock or after the ship is berthed at the gas station, debug the maximum flow function of the forced vaporizer outside the cargo hold, and simultaneously carry out the compressor supply mode durability test of the gas combustion unit (GCU).

[0059] In this stage, the gas LNG forcibly vaporized by the forced vaporizer is used as the fuel of the GCU.

[0060] When debugging the maximum flow function of the forced vaporizer and the endurance test of the compressor gas supply mode of the GCU are carried out simultaneously, the liquid supply pressure setting value of the gas pump in the cargo hold should not be lower than the outlet pressure setting value of the LD compressor in the GCU. When the forced vaporizer flow rate is increased to more than 50%, the liquid supply pressure of the gas pump can be gradually set to 120-130% of the outlet flow rate of the LD compressor but not higher than the trip setting value of the gas pipe safety valve to ensure the increase of the forced vaporizer outlet flow rate. Preferably, when the forced vaporizer flow rate is increased to more than 50%, the liquid supply pressure of the gas pump can be gradually set to 130% of the outlet flow rate of the LD compressor but not higher than the trip setting value of the gas pipe safety valve.

[0061] Preferably, the outlet temperature of the low load heater (ie, LD heater) is set to be controlled at 25-30 degrees Celsius.

[0062] When debugging the maximum flow function of the forced vaporizer and the endurance test of the compressor air supply mode of the GCU are carried out simultaneously, it is preferred that the flow setting of the LD compressor air supply mode in the GCU should always be kept 5-8% higher than the outlet flow of the forced vaporizer, so as to ensure that the outlet flow of the forced vaporizer can always be consumed by the GCU and steadily increase when the ship's main engine is not running, and the cargo hold pressure is always kept within a controllable range during the test at this stage. If the difference between the GCU combustion volume and the outlet flow of the forced vaporizer is too high, the flow of the LD compressor will increase too much, increase the load fluctuation of the gas phase pipeline of the air supply system, and cause system instability. If the difference between the GCU combustion volume and the outlet flow of the forced vaporizer is too low, the outlet flow of the forced vaporizer will not increase smoothly, which is likely to cause such operation to continue until the GCU flow reaches the maximum flow load of the LD compressor air supply mode.

[0063] When debugging the maximum flow function of the forced vaporizer and the endurance test of the compressor air supply mode of the GCU are carried out simultaneously, as a preference, after the GCU reaches the maximum flow in the LD compressor air supply mode, the maximum combustion flow of the GCU is maintained and the OPV (over pressure valve) valve of the air supply network is opened manually step by step. After each opening of the OPV valve, the outlet flow of the forced vaporizer can continue to be gradually increased.

[0064] Preferably, in the process of gradually opening the OPV valve of the gas supply network, the OPV valve is opened by 1% each time to maintain a stable pressure in the gas supply pipeline in the gas supply network and stable combustion of the GCU. After each opening of the OPV valve, the outlet flow of the forced vaporizer can continue to be gradually increased within 3%, and the OPV valve can be opened again after the pipeline pressure of the gas supply network is stabilized.

[0065] Preferably, in the process of gradually opening the OPV valve of the gas supply network, the condensate amount of the forced vaporizer and the LD heater in the GCU is continuously monitored. If the condensate increase of the forced vaporizer and the LD heater in the GCU is too high in a short period of time, the outlet flow of the forced vaporizer should be gradually reduced to keep the condensate amount controllable. Through this process, the maximum flow of the forced vaporizer can be achieved. When the maximum flow test of the forced vaporizer is completed, the various flow test conditions of the GCU in the LD compressor gas supply mode are also matched and completed, and there is no need to consume natural gas specifically for the endurance test of the GCU compressor gas supply mode.

[0066] The flow regulation of the forced vaporizer in this step is controlled by the ship's automatic control system (IAS).

[0067] This step can be carried out at the dock or after the ship is moored at the gas station.

[0068] S4. When the ship is berthed at the gas station, the energy consumption test of the main engine at different speeds in the unmanned cabin project under the engine room gas mode and the test of the automatic control of the forced vaporizer flow by the gas management system (GMS) are carried out simultaneously; the power increase and decrease test of the main engine in the unmanned cabin project under the engine room gas mode and the test of the automatic control of the forced vaporizer flow by the gas management system (GMS) are carried out simultaneously.

[0069] Specifically, when the energy consumption test of the ship's main engine at different speeds in the unmanned cabin project in the engine room gas mode is carried out simultaneously with the test of the automatic control of the forced vaporizer flow rate by the gas management system (GMS) in the ECOBOT project, the 100% flow rate of the GCU is set as the rated maximum gas consumption of the main engine, and the increase or decrease of the GCU gas flow rate is used to simulate the actual gas consumption of the main engine at different speeds. The GCU transmits its gas flow rate to the ship's automatic control system (IAS) in real time. The GMS automatically adjusts the outlet flow of the forced vaporizer according to the changes in the tank pressure in the liquid cargo tank. At the same time, the outlet flow of the gas pump is automatically adjusted synchronously through the load controller to increase the outlet flow of the pump. Even if the LNG ship is berthing at the gas station and the main engine is not actually running, the actual gas consumption of the main engine at different speeds can be accurately simulated through the GCU combustion consumption, realizing the functional debugging of the GMS to automatically increase and decrease the load of the forced vaporizer.

[0070] When the main engine power increase and decrease test in the unmanned cabin project in the engine room gas mode is carried out simultaneously with the gas management system (GMS) automatic control forced vaporizer flow test, the 100% flow of the GCU is set as the rated maximum gas consumption of the main engine, and the actual gas consumption of the main engine at different powers is simulated by increasing and decreasing the GCU gas flow. The GCU transmits its gas flow to the ship's automatic control system (IAS) in real time. The GMS automatically adjusts the outlet flow of the forced vaporizer according to the changes in the tank pressure in the liquid cargo tank. At the same time, the outlet flow of the gas pump is automatically adjusted synchronously through the load controller to increase the outlet flow of the pump. Even if the LNG ship is berthing at the gas station and the main engine is not actually running, the actual gas consumption (energy consumption) of the main engine at different powers can be accurately simulated through the GCU combustion consumption, realizing the functional debugging of the GMS automatic increase and decrease of the load of the forced vaporizer.

[0071] In order to ensure the safety and accuracy of the test, this step of the test is only carried out when the cargo hold pressure is less than 12Kpa to ensure that the cargo hold has sufficient pressure rise space. During the test, the 100% flow of the GCU needs to be set to the rated maximum gas consumption value of the main engine.

[0072] When conducting the test in this step, only one LD compressor can be operated to match the lower cargo hold pressure condition when the LNG ship is ballast sailing. The GCU always maintains a higher load combustion of 50% to 100% to match the main engine gas consumption condition requirements corresponding to the higher speed.

[0073] When conducting the test in this step, only the gas pump with liquid cargo tank is in operation, and the other non-liquid cargo tanks are warmed up after the liquid cargo tanks have completed partial unloading to the gas station. The warming up operation lasts for more than 8 hours to connect to the next step (i.e. matching the subsequent cargo hold heating process with the ship speed measurement process).

[0074] The cargo tank with liquid refers to a cargo tank storing liquid LNG, and the cargo tank without liquid refers to an empty cargo tank. In this embodiment, during the test, there is 1 cargo tank with liquid and 3 cargo tanks without liquid.

[0075] S5, synchronize the LNG cargo hold heating process with the ship speed measurement process to save time loss during the sea hold warming period.

[0076] When the heating process of the LNG ship's cargo hold and the ship's speed measurement process are carried out simultaneously, all non-liquid cargo tanks must have completed the first stage of warming-up operations with a large amount of expansion (i.e., continuous warming for more than 8 hours). When the warming-up operation of the liquid cargo tanks is carried out, the expansion caused by the volatilization of natural gas due to heat during the warming-up operation will be slowly absorbed by the GCU and non-liquid cargo tanks. Therefore, there will no longer be a phenomenon of drastic increase in cargo hold pressure. Therefore, the discharge time of the vent mast can be greatly shortened, allowing a large number of non-explosion-proof equipment required during the speed measurement test to be used safely.

[0077] It should be clear that the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Claims

1. A method for combining and matching gas test items for LNG carriers, characterized in that: The specific steps include: S1, cooling down the cargo hold of the LNG carrier at the dock, and simultaneously conducting a large-flow combustion test of the gas combustion unit (GCU) in the gravity gas supply mode at the end of the first cold cargo hold; S2, after the end of the cold hold period of the first cold hold, the process of the GCU flow test controlled by the gas management system (GMS) is carried out synchronously; S3, at the wharf or after the ship is berthed at the gas station, debug the maximum flow function of the forced vaporizer outside the cargo hold, and simultaneously carry out the endurance test of the compressor air supply mode of the GCU; S4, while the ship is berthed at the gas station, the energy consumption test of the main engine at different speeds in the engine room gas mode and the GMS automatic control forced carburetor flow test are carried out simultaneously; The main engine power increase and decrease test in the unmanned cabin project under cabin gas mode and the GMS automatic control forced carburetor flow test are carried out simultaneously; S5, synchronize the LNG cargo hold heating process with the ship speed measurement process to save time loss during the sea hold warming period.

2. The method for combining and matching gas test items for LNG carriers according to claim 1, characterized in that: The specific steps of step S1 are: First, the cargo holds of LNG carriers are cooled at the dock; When the cooling operation of the first refrigerated cargo hold is about to reach the end of the refrigeration period, the volatile gas main pipe of the first refrigerated cargo hold is separated from other cargo holds by valves, and the volatile gas pipe of the first refrigerated cargo hold is connected to the air inlet of the gas combustion unit (GCU) through a high-load heater; When the first refrigerated cargo hold reaches the end of the cold period, the amount of natural gas replacement between the first refrigerated cargo hold and the non-first refrigerated cargo hold is reduced, and the volatile gas formed in the first refrigerated cargo hold is supplied to the GCU through the volatile gas pipe, and a large-flow combustion test of the GCU's gravity air supply mode is carried out simultaneously.

3. The method for combining and matching gas test items for LNG carriers according to claim 1, characterized in that: At the end of the cold-hold period of the first cold-hold, when the cabin pressure in the first cold-hold reaches the high cabin pressure range between 15KPa-25KPa, a large-flow combustion test of the GCU in gravity air supply mode is carried out simultaneously.

4. The method for merging and matching gas test items for LNG carriers according to claim 1, characterized in that: In step S2, after the 21st hour of the first refrigerated cargo hold, the subsequent cargo hold cooling process and the GMS control GCU flow test process are carried out synchronously. At this stage, the volatile gas formed in the first refrigerated cargo hold can be completely consumed by GCU combustion, and the natural gas replacement gas path between the first refrigerated cargo hold and the non-first refrigerated cargo hold needs to be cut off.

5. The method for combining and matching gas test items for LNG carriers according to claim 1, characterized in that: When debugging the maximum flow function of the forced vaporizer in step S3 and performing the endurance test of the compressor air supply mode of the GCU simultaneously, the liquid supply pressure setting value of the gas pump in the cargo hold should not be lower than the outlet pressure setting value of the LD compressor in the GCU. When the forced vaporizer flow rate is increased to more than 50%, the liquid supply pressure of the gas pump can be gradually set to 120-130% of the LD compressor outlet flow rate but not higher than the trip setting value of the gas pipe safety valve to ensure the increase of the forced vaporizer outlet flow rate.

6. The method for combining and matching gas test items for LNG carriers according to claim 1 or 5, characterized in that: When debugging the maximum flow function of the forced vaporizer in step S3 and performing the endurance test of the compressor air supply mode of the GCU simultaneously, the flow setting of the LD compressor air supply mode in the GCU must always be kept 5-8% higher than the outlet flow of the forced vaporizer, so as to ensure that the outlet flow of the forced vaporizer can always be consumed by the GCU and steadily increase when the main engine of the ship is not running, and the cargo hold pressure is always kept rising within a controllable range during this stage of the test.

7. The method for combining and matching gas test items for LNG carriers according to claim 1 or 5, characterized in that: When the maximum flow rate function of the forced vaporizer is debugged and the endurance test of the compressor air supply mode of the GCU is performed synchronously in step S3, after the GCU reaches the maximum flow rate in the LD compressor air supply mode, the maximum combustion flow rate of the GCU is maintained and the OPV valve of the air supply network is opened manually step by step, and the outlet flow rate of the forced vaporizer continues to be gradually increased after each opening of the OPV valve; During the process of gradually opening the OPV valve of the gas supply network, continue to pay attention to the condensate amount of the forced vaporizer and the LD heater in the GCU. If the condensate increase of the forced vaporizer and the LD heater in the GCU is too high in a short period of time, the outlet flow of the forced vaporizer should be gradually reduced to keep the condensate amount controllable. Through this process, the maximum flow of the forced vaporizer can be achieved. When the maximum flow test of the forced vaporizer is completed, the various flow test conditions of the GCU in the LD compressor gas supply mode are also matched and completed, and there is no need to consume natural gas specifically for the endurance test of the GCU compressor gas supply mode.

8. The method for combining and matching gas test items for LNG carriers according to claim 7, characterized in that: In the process of gradually opening the OPV valve of the gas supply network, the OPV valve is opened by 1% each time to maintain stable pressure in the gas supply pipeline and stable combustion of the GCU. After opening the OPV valve each time, the outlet flow of the forced vaporizer can continue to be gradually increased within 3%, and the OPV valve can be opened again after the pipeline pressure of the gas supply network is stable.

9. The method for combining and matching gas test items for LNG carriers according to claim 1, characterized in that: In step S4, when the energy consumption test of the main engine at different speeds in the unmanned cabin project in the engine room gas mode and the forced vaporizer flow test automatically controlled by the gas management system (GMS) are carried out simultaneously, the 100% flow of the GCU is set as the rated maximum gas consumption of the main engine, and the actual gas consumption of the main engine at different speeds is simulated by increasing or decreasing the gas flow of the GCU. The GCU transmits its gas flow to the ship's automatic control system (IAS) in real time, and the GMS automatically adjusts the outlet flow of the forced vaporizer according to the change of the tank pressure in the liquid cargo tank, and also adjusts the outlet flow of the gas pump synchronously; When the main engine power increase and decrease test and the gas management system (GMS) automatic control forced vaporizer flow test are carried out simultaneously in the engine room gas mode, the 100% flow of the GCU is set as the rated maximum gas consumption of the main engine, and the actual gas consumption of the main engine at different powers is simulated by increasing and decreasing the GCU gas flow. The GCU transmits its gas flow to the ship's automatic control system (IAS) in real time. The GMS automatically adjusts the outlet flow of the forced vaporizer according to the changes in the tank pressure in the liquid cargo tank, and also adjusts the outlet flow of the gas pump synchronously; During the execution of this step, only the fuel gas pump of the cargo tank with liquid is in operation, and the other non-cargo tanks are warmed up after the cargo tank with liquid is partially unloaded to the gas station.

10. The method for combining and matching gas test items for LNG carriers according to claim 1, characterized in that: When the LNG ship cargo tank heating process and the ship speed measurement process are carried out simultaneously in step S5, the non-cargo tank must have completed the first stage of warm-up operation with a large expansion amount. When the cargo tank warm-up operation is carried out, the expansion amount of the cargo tank is slowly absorbed by the GCU and the non-cargo tank, which greatly shortens the discharge time of the vent mast and enables a large number of non-explosion-proof equipment required during the speed measurement test to be used safely.

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