A marine liquid ammonia fuel filling system

Abstract

The present application relates to the technical field of marine fuel filling, and particularly relates to a marine liquid ammonia fuel filling system, comprising the following steps: step S1, collecting data; step S2, calculating the real-time refrigeration power of the ship fuel tank in the filling process; and controlling the working state of the refrigeration system inside the ship fuel tank; step S3, controlling the filling speed through the difference between the maximum allowable refrigeration power of the ship fuel tank and the real-time refrigeration power. Through the above technical scheme, there is heat loss in the filling process, and the lost heat is much greater than the heat loss speed of the ship fuel tank in the closed state, which will cause more parts of the injected liquid ammonia to be gasified, so it is necessary to increase the refrigeration power of the ship fuel tank to make the injected fuel not be gasified too much after entering the fuel tank, so as to make the pressure of the whole filling system controllable and ensure the safety of filling.

Description

Technical Field

[0001] This invention relates to the field of marine fuel refueling technology, and in particular to a marine liquid ammonia fuel refueling system. Background Technology

[0002] Ammonia is a colorless gas with a density lower than air under ambient conditions, and its boiling point is -33.5℃ at ambient pressure. Ammonia is a toxic gas with a distinctly pungent odor. Low concentrations of ammonia have a significant irritant effect on mucous membranes, while high concentrations can cause tissue necrosis. Ammonia mixed with air can form an explosive mixture, which can ignite and explode upon contact with open flames or high heat; its explosive limits are 15.7%–27.4%. Ammonia also has a certain degree of corrosiveness.

[0003] Therefore, safety must be taken into account when refueling ships with liquid ammonia to avoid leakage caused by excessive pressure and to ensure safe refueling. Summary of the Invention

[0004] The purpose of this invention is to provide a marine liquid ammonia fuel refueling system to solve the problems existing in the prior art.

[0005] The above-mentioned technical objective of the present invention is achieved through the following technical solution:

[0006] A marine liquid ammonia fuel bunkering system includes an LNG arm, a tank truck, and a filling system. A floating platform is fixedly installed at the rear of the tank truck, the LNG arm is fixedly installed on the top of the floating platform, and the filling system is fixedly installed on the tank truck. The filling system is used to control the LNG arm.

[0007] By adopting the above technical solution, since liquid ammonia fuel is refueled to ships docked at berths via tank trucks, the ships will sway with the waves of seawater or river water when they are docked. This requires a buffer module to connect the tank truck and the ship to avoid a rigid connection between the tank truck and the ship. A floating platform is a good buffer module. The LNG arm is installed on the floating platform. During the refueling process, the end of the LNG arm must be firmly fixed to the ship's refueling port to ensure sealing performance. Therefore, the end of the LNG arm fixed to the floating platform needs to be connected to the inside of the tank truck's storage tank through an insulated high-pressure hose. The filling system is mainly used to monitor the entire refueling process and ensure that the liquid ammonia fuel is safely and stably injected into the ship's fuel tank.

[0008] In a further embodiment, the floating platform includes a bottom plate and a top plate. The bottom plate is fixedly connected to the tank truck. A plurality of springs are fixedly installed on the top of the bottom plate, and the top plate is fixedly installed on the top of the springs. The axis of each spring is vertically arranged.

[0009] By adopting the above technical solution, in actual use, through holes need to be set at the four corners of the top of the top plate and the bottom plate. When not filling, bolts are used to pass through from the top of the top plate and out from the bottom of the bottom plate, and then locked with nuts to limit the relative movement range of the top plate and the bottom plate, so as to prevent the LNG arm from shaking randomly during the movement of the tank truck.

[0010] In a further embodiment, the filling system includes a cryogenic submersible centrifugal pump, a power monitoring module, and a flow meter located at the bottom of the tanker's storage tank. The power monitoring module monitors the operating power of the cryogenic submersible centrifugal pump, and the flow meter measures the real-time internal flow velocity of the LNG arm. The top and bottom plates of the floating platform each have through holes at their four corners, with bolts inserted through these holes to limit the relative movement of the top and bottom plates. The LNG arm is fixed to one end of the floating platform and connected to the inside of the tanker's storage tank via an insulated, high-pressure resistant hose. The power monitoring module includes a voltage transformer and a current transformer for collecting the real-time operating voltage and current of the cryogenic submersible centrifugal pump.

[0011] The refueling system also includes a pressure control method for controlling the pressure during the refueling process, the pressure control method comprising the following steps:

[0012] Step S1: Data acquisition. The real-time operating current and voltage of the cryogenic submersible centrifugal pump are acquired through the power monitoring module. The internal pressure of the ship's fuel tank is detected through the ship's onboard fuel tank pressure sensor. The internal temperature of the tank truck's storage tank, the ambient temperature, the internal temperature of the LNG arm, and the internal temperature of the ship's fuel tank are also acquired through the temperature acquisition unit.

[0013] Step S2: Calculate the real-time cooling power of the ship's fuel tank during the refueling process. ; and through Control the operating status of the internal refrigeration system of the ship's fuel tank;

[0014] Step S3: Measure the maximum permissible cooling capacity of the ship's fuel tank. With real-time cooling power The difference in injection rate is used to regulate the infusion rate.

[0015] By adopting the above technical solution, heat loss occurs during the refueling process, and the rate of heat loss is much greater than that of the ship's fuel tank in a closed state. This will cause more of the injected liquid ammonia to be vaporized. Therefore, it is necessary to increase the cooling capacity of the ship's fuel tank to prevent excessive vaporization of the injected fuel after it enters the fuel tank, thereby making the pressure of the entire refueling system controllable and ensuring the safety of refueling.

[0016] In a further embodiment, step S2 further includes:

[0017] Step S21: Set up the heat exchange and power calculation model for the fuel tank;

[0018] Step S22: Determine the maximum cooling capacity of the ship's fuel tank;

[0019] Step S23: Set up a safe cooling power control model.

[0020] In a further embodiment, the infusion rate control step of step S3 includes:

[0021] Step S31: Based on the maximum allowable cooling capacity of the ship's fuel tank With real-time cooling power The difference between them is used to calculate the maximum permissible infusion rate, expressed in cubic meters per minute.

[0022] Step S32: Set the operating power of the cryogenic submersible centrifugal pump;

[0023] Step S33: The cryogenic submersible centrifugal pump operates at 98% of its set power.

[0024] In a further embodiment, setting , It refers to the cooling capacity of the ship's fuel tanks when they are not being filled. M represents the current mass of ammonia fuel in the fuel tank, in kilograms. The ambient temperature is calculated in Fahrenheit. These are constants related to the tank structure, materials, and heat transfer coefficient, with units of W / K and W / (kg·K), respectively.

[0025] In a further embodiment, setting , This refers to the real-time power output of the ship's fuel tanks during the refueling process. Injected traffic is The fuel injection temperature is Storage temperature is If the specific heat capacity of ammonia is C, then the power required to cool the injected fuel is... , Add heat load to the filling system.

[0026] In summary, the present invention has the following beneficial effects:

[0027] 1. Calculations show that heat loss occurs during the refueling process, and the rate of heat loss is much greater than that of the ship's fuel tank in a closed state. This will cause more of the injected liquid ammonia to be vaporized. Therefore, it is necessary to increase the cooling capacity of the ship's fuel tank to prevent excessive vaporization of the injected fuel after it enters the fuel tank, thereby making the pressure of the entire refueling system controllable and ensuring the safety of refueling. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the overall structure of the dispensing system of the present invention.

[0029] In the diagram, 1 is the floating platform; 2 is the LNG boom; and 3 is the tank truck. Detailed Implementation

[0030] The present invention will be further described in detail below with reference to the accompanying drawings.

[0031] It should be noted that in the description of this invention, any descriptions of orientation, such as up, down, front, back, left, right, etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings. They are only for the purpose of facilitating the description of this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed or operated in a specific orientation, and should not be construed as a limitation of this invention.

[0032] Example 1:

[0033] like Figure 1 As shown, a marine liquid ammonia fuel refueling system includes an LNG arm 2, a tank truck 3, and a filling system. A floating platform 1 is fixedly installed at the rear of the tank truck 3, the LNG arm 2 is fixedly installed on the top of the floating platform 1, and the filling system is fixedly installed on the tank truck 3. The filling system is used to control the LNG arm 2. The floating platform includes a bottom plate and a top plate. The bottom plate is fixedly connected to the tank truck 3. Multiple springs are fixedly installed on the top of the bottom plate, and the top plate is fixedly installed on the top of the springs. The axis of each spring is vertically arranged. The filling system includes a cryogenic submersible centrifugal pump, a power monitoring module, and a flow meter located at the bottom of the storage tank in the tank truck 3. The power monitoring module is used to monitor the operating power of the cryogenic submersible centrifugal pump, and the flow meter is used to measure the real-time internal flow velocity of the LNG arm 2.

[0034] Pressure regulation methods include the following steps:

[0035] Step S21: Set up the heat exchange and power calculation model for the fuel tank. For a new energy ship using ammonia fuel as fuel, the real-time power of its fuel storage tank is... Operating power is , This represents the power supplied to the fuel tanks during normal navigation or anchoring. The power is required during the refueling process. Because the fuel tank comes into contact with the external environment during refueling (the filling system consisting of tank truck 3 and LNG arm 2), the power needs to be increased. Also, because fuel is being continuously injected, the power needs to be adjusted according to the fuel injection flow rate to keep the internal temperature of the fuel tank constant and prevent excessive vaporization of ammonia fuel.

[0036] To ensure real-time cooling capacity during refueling, external ammonia fuel is injected through tanker truck 3. The injected fuel temperature may be higher than the storage temperature, and the refueling pipeline's contact with the environment introduces additional heat load. Therefore, Need to be Based on this, the flow rate is increased and dynamically adjusted according to the injection flow rate to ensure a constant temperature. Let the injection flow rate be... The fuel injection temperature is Storage temperature is If the specific heat capacity of ammonia is C, then the power required to cool the injected fuel is... In addition, the refueling process also incurs additional heat load. The total power is: In actual use, This is related to flow rate or can be considered a constant, requiring real-time adjustment through control algorithms. To maintain a constant temperature, this parameter It can be obtained through testing, such as the heat transfer of the entire refueling pipeline during the refueling process, or it can be understood as the heat exchanged with the outside world during the process of liquid ammonia being injected into the ship's fuel tank from inside the tanker of tanker truck 3 through hoses and LNG arm 2.

[0037] about , It can be understood as a constant value, which is only related to the remaining fuel in the ship's fuel tank and the ambient temperature. The higher the ambient temperature, the more stable the fuel supply. The larger the ship, the more fuel it has in its fuel tanks. The larger, M represents the current mass of ammonia fuel in the fuel tank, in kilograms. The ambient temperature is calculated in Fahrenheit. These are constants related to the tank structure, materials, and heat transfer coefficient, with units of W / K and W / (kg·K), respectively.

[0038] Regarding step S22, determining the maximum cooling capacity of the ship's fuel tank, the cooling capacity of each ship's fuel storage tank has an upper limit, which can be obtained directly from the ship's end.

[0039] Regarding step S23, setting a safe cooling power control model, in order to cope with emergencies, the maximum cooling power in actual use needs to be set to between 90% and 95% of the maximum cooling power of the ship's fuel tank.

[0040] The real-time operating current I and voltage U of the cryogenic submersible centrifugal pump are collected by the power monitoring module, and the real-time shaft power of the pump is calculated as P_pump = √3·U·I·cosφ·η, where cosφ is the power factor and η is the motor efficiency. These two parameters can be obtained from the pump manufacturer's characteristic curve. This power data is used to determine whether the pump is operating in the high-efficiency range and serves as a reference for subsequent calculations.

[0041] The real-time pressure P_tank inside the ship's fuel tank is collected at least once per second by the ship's onboard fuel tank pressure sensor. The pressure data is the primary indicator for judging the safety status. When P_tank approaches the set safety threshold, the control system should immediately take measures to reduce speed or stop refueling.

[0042] Meanwhile, the system needs to acquire temperature data at multiple key points through temperature acquisition units, such as Pt100 platinum resistance temperature sensors, including: the liquid ammonia temperature T_truck inside the storage tank of tank truck 3, the ambient temperature T_env at the refueling site, the liquid ammonia temperature T_arm in the flow channel inside LNG arm 2 (sensors can be embedded at the joints of LNG arm 2), and the liquid ammonia temperature T_tank inside the ship's fuel tank. These temperature data are aggregated to the central control unit through a PLC (programmable logic controller) or DCS (distributed control system).

[0043] Every ship's fuel tank refrigeration system (usually a reliquefaction unit or refrigeration unit) has its rated maximum refrigeration capacity. This power value is a hard constraint, representing the upper limit of the system's hardware capabilities. Before the refueling operation begins, the control unit needs to obtain this parameter through the ship's data interface or by manual input. This is used to determine the maximum allowable filling rate and prevent the required cooling power from exceeding the system's capacity, which could lead to cooling failure and temperature runaway.

[0044] To allow for adjustment margins in the control system and to cope with sudden environmental changes or equipment performance fluctuations, the refrigeration system should not be pushed to its limits. Therefore, this method sets a maximum allowable refrigeration power. The maximum permissible cooling capacity during actual use is set to between 90% and 95% of the maximum cooling capacity of the ship's fuel tank, i.e. This design ensures that the cooling capacity still has room to be adjusted upwards when the system needs fine-tuning or when there is a minor disturbance, avoiding loss of control due to hitting the ceiling.

[0045] After clarifying the maximum permissible cooling capacity that a ship's fuel tank can safely provide. and the base heat load in the non-fueling state Then, the remaining cooling capacity that can be used to cool the injected fuel and offset the additional heat from the pipes can be calculated. , This difference The safe flow rate during the refueling process is directly determined, therefore Must meet Therefore, the maximum permissible mass flow rate can be derived. , ; in the initial control When the value is small or negligible, a simplified formula can also be used: Estimation is required; since flow meters typically measure volumetric flow rate, it is necessary to convert mass flow rate to volumetric flow rate, expressed in cubic meters per minute (m³ / min) or liters per minute (L / min), for easy understanding by operators. The conversion formula is as follows: ; where ρ is the density of liquid ammonia at the current temperature.

[0046] At the specific execution level of infusion rate control, the following sub-steps are included:

[0047] Step S31: The central control unit calculates the maximum allowable injection rate (cubic meters / minute) under the current operating conditions in real time based on the above model. This rate value is used as the target control value of the cryogenic submersible centrifugal pump.

[0048] Step S32: Based on the target injection rate, the required pump speed or motor frequency is deduced from the pump's characteristic curve, and then the operating power of the cryogenic submersible centrifugal pump is set. Since the pump's power and flow rate are approximately cubic, accurately setting the power is key to ensuring precise flow rate.

[0049] Step S33: In actual control, to avoid power overshoot or oscillation, the controller does not directly output 100% of the set power, but first executes at 98% of the set power. This 2% margin serves as a control dead zone, preventing frequent pump adjustments due to minor fluctuations in the feedback signal, thus making the system operation more stable. Subsequently, through real-time feedback from the flow meter, a PID control algorithm is used to fine-tune the pump power, ensuring that the actual flow rate accurately and smoothly approaches the target injection rate.

[0050] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0051] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A marine liquid ammonia fuel refueling system, characterized in that: The system includes an LNG arm, a tank truck, and a filling system. A floating platform is fixedly mounted at the rear of the tank truck. The LNG arm is fixedly mounted on top of the floating platform, and the filling system is fixedly mounted on the tank truck. The filling system controls the LNG arm. The floating platform includes a bottom plate and a top plate. The bottom plate is fixedly connected to the tank truck. Multiple springs are fixedly mounted on the top of the bottom plate, and the top plate is fixedly mounted on top of the springs. The axis of each spring is vertically oriented. The filling system includes a cryogenic submersible centrifugal pump, a power monitoring module, and a flow meter located at the bottom of the tank truck's storage tank. The power monitoring module monitors the operating power of the cryogenic submersible centrifugal pump, and the flow meter measures the real-time internal flow velocity of the LNG arm. The top and bottom plates of the floating platform each have through holes at their four corners, with bolts inserted through these holes to limit the relative movement of the top and bottom plates. The LNG arm is fixed to one end of the floating platform and connected to the inside of the tank truck's storage tank via an insulated, high-pressure resistant hose. The power monitoring module includes a voltage transformer and a current transformer to collect the real-time operating voltage and current of the cryogenic submersible centrifugal pump. The refueling system also includes a pressure control method for controlling the pressure during the refueling process, the pressure control method comprising the following steps: Step S1: Data acquisition. The real-time operating current and voltage of the cryogenic submersible centrifugal pump are acquired through the power monitoring module. The internal pressure of the ship's fuel tank is detected through the ship's own fuel tank pressure sensor. The internal temperature of the tank truck's storage tank, the ambient temperature, the internal temperature of the LNG arm, and the internal temperature of the ship's fuel tank are obtained through the temperature acquisition unit. Step S2: Calculate the real-time cooling power of the ship's fuel tank during the refueling process. ; and through Control the operating status of the internal refrigeration system of the ship's fuel tank; Step S3: Measure the maximum permissible cooling capacity of the ship's fuel tank. With real-time cooling power The difference in perfusion rate is used to regulate the infusion rate; Step S2 further includes: Step S21: Set up the heat exchange and power calculation model for the fuel tank; Step S22: Determine the maximum cooling capacity of the ship's fuel tank; Step S23: Set the safe cooling power control model; set up This refers to the cooling capacity of a ship's fuel tank in a non-filled state. M represents the current mass of ammonia fuel in the fuel tank, in kilograms. The ambient temperature is calculated in Fahrenheit; α and β are constants related to the tank structure, materials, and heat transfer coefficient, with units of W / K and W / (kg·K), respectively.

2. The marine liquid ammonia fuel refueling system according to claim 1, characterized in that, The infusion rate control step in step S3 includes: Step S31: Based on the maximum allowable cooling capacity of the ship's fuel tank With real-time cooling power The difference is used to calculate the maximum permissible infusion rate; Step S32: Set the operating power of the cryogenic submersible centrifugal pump according to the maximum injection rate; Step S33: The cryogenic submersible centrifugal pump operates at 98% of its set power.

3. A marine liquid ammonia fuel refueling system according to claim 2, characterized in that, set up This refers to the real-time cooling capacity of the ship's fuel tanks during the refueling process. Injected traffic is The fuel injection temperature is Storage temperature is If the specific heat capacity of ammonia is C, then the power required to cool the injected fuel is... , Add heat load to the filling system.

4. A marine liquid ammonia fuel refueling system according to claim 3, characterized in that, The maximum allowable cooling power It is 90% to 95% of the maximum cooling capacity of the ship's fuel tank.

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