A fluid swivel based spin-tube sail de-icing system and control method

Abstract

The application belongs to the technical field of ship wind power boosting, and relates to a rotating cylinder wind sail deicing system based on a fluid rotary joint and a control method. The system uses the waste heat generated by the cylinder sleeve water of a ship main engine or a waste gas boiler as a heat source, and through a closed circulation loop, fluid medium is introduced into a high-speed rotating rotating cylinder internal spiral pipe or a sandwich flow channel through a multi-channel fluid rotary joint, so that the cylinder wall surface is uniformly heated. The system adopts a coaxial rotary joint structure of "inner pipe inflow and outer pipe backflow", cooperates with a balanced end face seal and an O-shaped ring to ensure leak-free transmission, and integrates environmental temperature and humidity, infrared cylinder wall temperature and vibration sensors, and switches the ice prevention, deicing and shutdown blowing modes intelligently by a PLC. The application discards high-energy-consumption electric heating slip rings, realizes zero additional power consumption, intrinsic safety and high-reliability ice prevention and deicing, significantly improves the ship energy efficiency index, and is suitable for cold region navigation scenes such as oil tankers and polar ships.

Description

Technical Field

[0001] This invention relates to the field of ship wind-powered propulsion technology, and in particular to a rotary sail de-icing system and control method based on a fluid rotary joint. Background Technology

[0002] Rotary propellers utilize the Magnus effect to provide auxiliary thrust to ships and are an important technology for energy conservation and emission reduction in the shipping industry. However, when ships sail in high-latitude, cold waters, the surface of the rotor is prone to icing. Icing can lead to the following serious consequences: 1. It disrupts the aerodynamic shape, resulting in a significant decrease in propulsion efficiency; 2. Uneven ice distribution causes severe dynamic imbalance in the rotating body, generating violent vibrations that may damage bearings or even cause breakage; 3. Falling ice blocks threaten the safety of deck personnel.

[0003] Current technologies primarily employ electric heating, which involves laying resistance wires or electric heating films inside the cylinder wall and supplying power through high-power slip rings. However, these existing technologies have significant drawbacks:

[0004] 1) Extremely high energy consumption: De-icing requires enormous thermal power, consuming precious marine generator electrical energy.

[0005] 2) Poor reliability of slip rings: When a large current passes through the slip ring, it generates a lot of heat and electric sparks, and there are explosion-proof safety hazards on oil and gas transport ships.

[0006] 3) Difficult to maintain: The carbon brushes of the slip rings are wear parts, and replacement and maintenance are extremely inconvenient.

[0007] Publication No.: CN103950531B describes a vessel equipped with a vertically arranged rotating cylinder. The vessel includes a hull and a propulsion system comprising an internal combustion engine, an exhaust system, and a propulsion unit. The vessel also has at least one vertically arranged cylinder with a vertical axis, adapted to rotate about its vertical axis. The vessel is characterized in that the exhaust system includes an exhaust pipe and a muffler, and the vertically arranged cylinder is arranged around the exhaust pipe and the muffler. However, this technical solution does not address the icing problem of the rotating cylinder in low-temperature environments, nor does it propose any anti-icing or de-icing measures.

[0008] Therefore, developing an anti-icing and de-icing system that utilizes the ship's own waste heat and does not require high-power electrical transmission is an urgent problem to be solved in this field. Summary of the Invention

[0009] In view of this, the present invention aims to propose a rotary drum de-icing system and control method based on a fluid rotary joint, so as to solve the problems of high energy consumption, low safety and high maintenance cost of existing electric heating de-icing solutions.

[0010] This invention pioneered the use of waste heat from ship main engine cylinder liner water or exhaust boilers as the sole heat source to construct a closed-loop hot fluid circulation circuit, achieving green anti-icing with "zero additional energy consumption." It also designs a highly reliable dual-channel fluid rotary joint, employing a balanced end-face seal and O-ring composite seal structure, along with coaxial inlet / outlet channels, within a range of 0–300°. The system achieves leak-free heat transfer under high-speed rpm rotation. A spiral coil or guide jacket is integrated into the vortex jacket or inner wall to form a closed heat exchange loop that rotates synchronously with the cylinder, ensuring uniform heat transfer to the outer surface while maintaining the integrity of the aerodynamic shape. An intelligent control system based on multi-source sensing is constructed to achieve four adaptive operating modes: anti-icing warning, powerful de-icing, energy efficiency optimization, and fault protection. It also features automatic purging and emptying upon shutdown, effectively preventing pipeline freezing and cracking. The entire system has no electric heating elements and no risk of slip ring sparks, ensuring inherent safety. Its modular design allows for flexible adaptation to single-cylinder or multi-cylinder vortex sail layouts, making it particularly suitable for explosion-proof vessels such as oil tankers and LNG carriers. This significantly reduces maintenance costs and greatly improves the reliability and safety of navigation in polar and cold regions.

[0011] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0012] One object of this invention is to disclose a rotary drum de-icing system for sails based on a fluid rotary joint, comprising a base and a rotary drum disposed on the base.

[0013] The heat source supply unit is connected to the water circulation loop of the ship's main engine cylinder liner or the hot water well outlet of the waste gas boiler, and is used to extract waste heat from the ship and provide high-temperature heat transfer fluid.

[0014] A fluid circulation drive unit, located downstream of the heat source supply unit, includes a corrosion-resistant circulation pump, a flow regulating valve, a pressure transmitter, and a high-level expansion tank, used to drive the circulation of the heat transfer fluid and maintain stable system pressure.

[0015] A fluid rotation transfer device includes a first fluid rotation joint located at the upper end of the rotating cylinder and a second fluid rotation joint located at the lower end of the rotating cylinder; wherein, a central fixed pipe is coaxially arranged inside the rotating cylinder, the first fluid rotation joint is located between the central fixed pipe and the rotating cylinder, and is used to introduce heat-carrying fluid from the liquid supply pipe inside the central fixed pipe into the rotating cylinder; the second fluid rotation joint is located between the bottom of the rotating cylinder and the base, and is used to discharge the heat-exchanged fluid;

[0016] The swirl heat exchange unit is integrated into the inner wall or interlayer of the swirl, with its inlet connected to the first fluid rotary joint and its outlet connected to the second fluid rotary joint, forming a complete closed heat exchange circuit.

[0017] The control unit is electrically connected to the sensors and actuators in each unit and is used to automatically switch between anti-icing, de-icing, and shutdown modes according to the environment and operating status.

[0018] Furthermore, the heat source supply unit is connected to the high-temperature outlet of the ship's main engine cylinder liner water circulation loop via a temperature control valve group, or the heat source supply unit is directly connected to the hot water well outlet of the waste gas boiler.

[0019] Furthermore, the first fluid rotary joint is an annular structure, with one end fixedly connected to the rotary cylinder and communicating with the inlet of the rotary cylinder heat exchange unit, and the other end facing the central fixed tube and abutting against its end face.

[0020] The first fluid rotary joint has an annular cavity inside, and an opening groove is opened at the end away from the rotary cylinder. The opening groove is aligned and connected with the outlet of the liquid supply pipeline in the central fixed tube.

[0021] Furthermore, the swirl heat exchange unit is a multi-head spiral coil, consisting of 2–4 sets of high-temperature resistant PEX tubes or 316L stainless steel tubes evenly distributed along the circumference of the swirl cylinder inside the cylinder wall.

[0022] Furthermore, the control unit is connected to the following sensor subsystems:

[0023] The condition monitoring sensors include temperature transmitters and pressure transmitters located at the inlet and outlet of the fluid rotary transfer device, and an infrared non-contact temperature sensor installed on the top of the rotary drum.

[0024] Environmental sensing sensors, including ambient temperature and humidity sensors for the open deck area;

[0025] Safety monitoring sensors include a vibration acceleration sensor on the base and a flow meter in the pipeline.

[0026] Furthermore, the control unit is configured to execute the following control logic:

[0027] When the ambient temperature is ≤3℃ and the relative humidity is ≥80%, start the circulation pump to run at low frequency, maintain the wall temperature of the rotary drum at 2–5℃, and enter the anti-icing mode.

[0028] When the vibration amplitude exceeds 0.5 mm / s RMS or the local cylinder wall temperature is below 0℃ for 5 minutes, switch to the powerful de-icing mode, fully open the flow regulating valve and run the circulation pump at full frequency;

[0029] The pump frequency is dynamically adjusted based on the temperature difference ΔT between the inlet and outlet water: if ΔT < 2℃, the frequency is reduced to save energy; if ΔT > 10℃, the frequency is increased to enhance heating.

[0030] Furthermore, it also includes a purging and venting subsystem, which includes an electromagnetic valve and a compressed air source. When the machine is stopped, the subsystem is opened by the control unit to push the residual fluid in the pipeline and inside the vortex back into the storage tank to prevent freezing at low temperatures.

[0031] Furthermore, the heat transfer fluid is an ethylene glycol-water mixture with a freezing point not higher than -25°C.

[0032] Another object of the present invention discloses a control method for a rotary sail de-icing system based on a fluid rotary joint, comprising the following steps:

[0033] S1: System initialization, check liquid level, valve status and leakage;

[0034] S2: Real-time acquisition of ambient temperature and humidity, cylinder wall temperature and vibration data;

[0035] S3: If the ambient temperature is ≤2℃ and the humidity is ≥70%, activate the anti-icing mode;

[0036] S4: If abnormal vibration or local icing is detected, switch to powerful de-icing mode;

[0037] S5: When shutting down, perform compressed air purging for 3–5 minutes to completely drain the liquid;

[0038] S6: Enters low-power standby mode and continuously monitors environmental parameters.

[0039] Furthermore, in step S5, the purging pressure is 0.3–0.5 MPa. After purging is completed, the pressure sensor confirms that there is no liquid residue in the pipeline, and then the system power is turned off to achieve dry shutdown.

[0040] Compared with the prior art, the rotary drum sail de-icing system and control method based on a fluid rotary joint of the present invention have the following advantages:

[0041] 1. This invention employs a closed-loop hot fluid circulation system based on a fluid rotary joint to efficiently introduce the low-temperature waste heat generated by the ship's main engine cylinder liner water or exhaust gas boiler into the heat exchange channel inside the high-speed rotating rotary sail. This allows the heat to be evenly conducted along the cylinder wall to the outer surface, actively maintaining the cylinder temperature above the freezing point in extremely cold environments. This significantly improves the overall energy utilization efficiency of the ship and solves the problems of high energy consumption, low safety, and high maintenance costs of existing electric heating de-icing solutions.

[0042] 2. This invention constructs an integrated heat transfer architecture of a multi-channel fluid rotary joint and an embedded spiral coil / jacketed flow channel, combined with a composite sealing system of a balanced end-face mechanical seal and an O-ring auxiliary seal, to ensure stable heat transfer of high-temperature antifreeze with no leakage, low wear, and long service life under high-speed rotation conditions of 0–300 rpm.

[0043] 3. This invention integrates multi-source sensor feedback of ambient temperature and humidity, cylinder wall infrared temperature and vibration status, and intelligently switches between anti-icing, de-icing and shutdown purging modes. This avoids eccentric vibration caused by local overheating or uneven ice melting, eliminates the risk of pipeline freezing and cracking, and the whole set of equipment is inherently safe and maintenance-free. It is suitable for ship scenarios with strict explosion-proof requirements such as oil tankers and LNG ships. Attached Figure Description

[0044] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0045] Figure 1 This is a schematic diagram of the system structure of the present invention;

[0046] Figure 2 This is a schematic diagram of the cross-section of the rotary cylinder of the present invention;

[0047] Figure 3 This is the logic control flowchart of the present invention;

[0048] Figure 4 This is a cross-sectional view of the fluid rotation transmission device of the present invention;

[0049] Figure 5 This is an exploded view of the structure of the fluid rotation transmission device of the present invention.

[0050] Explanation of reference numerals in the attached figures:

[0051] 1. Heat source supply unit; 2. Fluid circulation drive unit; 3. Fluid rotation transmission device; 301. First fluid rotary joint; 302. Annular cavity; 4. Rotary heat exchange unit; 5. Rotary cylinder; 6. Central fixed pipe; 7. Base; 8. Auxiliary sealing structure. Detailed Implementation

[0052] To make the technical means and objectives and effects of the present invention easier to understand, the embodiments of the present invention will be described in detail below with reference to specific illustrations.

[0053] It should be noted that all directional and positional terms used in this invention, such as "up," "down," "left," "right," "front," "back," "vertical," "horizontal," "inner," "outer," "top," "lower," "lateral," "longitudinal," and "center," are only used to explain the relative positional relationships and connections between components in a specific state. They are merely for the convenience of describing the invention and do not require the invention to be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on the invention. Furthermore, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated.

[0054] In the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0055] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0056] A rotary sail is a ship propulsion device that utilizes wind energy. It uses an electric motor to drive a vertical cylinder to rotate at high speed, generating Magnus force under crosswinds, thereby propelling the ship forward and significantly reducing main engine fuel consumption.

[0057] The PLC serves as the system's brain, responsible for executing logic control, processing signals, and coordinating all equipment. The integrated frequency converter acts as a precision actuator, receiving PLC commands and precisely controlling motor speed and torque. The human-machine interface (HMI) is an interactive window providing visual operations such as parameter setting, status monitoring, and alarm handling.

[0058] like Figures 1 to 5As shown, this invention provides a waste heat de-icing system for a rotary sail based on a fluid rotary joint. The system mainly comprises five functional modules: a heat source supply unit 1, a fluid circulation drive unit 2, a fluid rotation transmission device 3, a rotary sail heat exchange unit 4, and a control unit. These modules work collaboratively, utilizing waste heat from the ship's main engine to achieve intelligent de-icing of the surface of the high-speed rotating rotary drum 5. No additional electrical energy input is required, ensuring safety and reliability. This achieves cascaded energy utilization, avoiding the tens of kilowatts of power consumption in traditional electric heating schemes, significantly reducing ship auxiliary energy consumption, improving energy efficiency, and completely eliminating the risk of electrical sparks. This allows the system to be safely applied to ships with stringent explosion-proof requirements, such as oil tankers and LPG carriers. The system also features automatic purging and venting functions during shutdown, effectively preventing residual liquid in the pipelines and inside the rotary drum 5 from freezing and cracking in extremely cold environments, significantly improving the long-term operational reliability and maintenance-free nature of the equipment in high-latitude sea areas.

[0059] In Example 1, the input end of the heat source supply unit 1 is connected to the high-temperature outlet of the ship's main engine cylinder liner water circulation loop via pipelines and a temperature control valve assembly. This loop typically outputs a heat transfer medium with a temperature of 75–90°C as a low-grade waste heat carrier generated during diesel engine operation.

[0060] Specifically, a DN50 stainless steel pipeline is led out from the main engine cylinder liner water outlet, passing sequentially through a filter, a three-way regulating valve V1, and a shut-off valve V2, before connecting to the inlet of the fluid circulation drive unit 2. The system heat transfer medium can be directly the main engine cylinder liner water, suitable for freshwater cooling systems, or in a closed anti-icing circuit, a glycol-water mixed antifreeze can be used, with indirect heat exchange between the system and the main engine circuit via a plate heat exchanger, depending on the ship type.

[0061] This solution is suitable for conventional merchant ships such as bulk carriers and container ships equipped with medium-to-high-speed diesel main engines. Since the main engine runs continuously during navigation, the cylinder liner water temperature is stable and the flow rate is sufficient, providing a reliable and continuous heat source for the anti-icing and de-icing system. It utilizes the waste heat inevitably generated during main engine operation, requiring no additional energy input; the heat source temperature is moderate and fluctuates little, which is beneficial for stable system temperature control.

[0062] The piping layout is simple and easy to integrate into the existing engine room piping system, resulting in low retrofit costs.

[0063] In this embodiment 2, the input end of the heat source supply unit 1 is connected to the hot water well outlet of the ship's exhaust boiler via pipelines and a temperature control valve assembly. The exhaust boiler uses the waste heat from the main engine's flue gas to heat water, and its hot water well can typically provide saturated hot water or low-pressure steam condensate at 80–120°C, which is a high-quality waste heat resource.

[0064] Specifically, an insulated pipeline is drawn from the outlet of the hot water well of the waste gas boiler, passes through a check valve and a filter, and then connects to a three-way regulating valve V1, before being connected to the inlet of the circulating pump via a shut-off valve V2. Because the hot water well medium has high cleanliness and low oxygen content, the system can directly use deionized water or low-concentration antifreeze as the heat transfer medium, reducing the risk of corrosion.

[0065] This solution is particularly suitable for large oil tankers, LNG carriers, or ocean-going research vessels equipped with exhaust gas boilers. Especially when the main engine is running at low load, the cylinder liner water temperature may be insufficient, but the exhaust gas boiler can still maintain a higher hot water temperature through exhaust gas waste heat, ensuring the availability of the anti-icing and de-icing system under all operating conditions. It utilizes higher-grade exhaust gas waste heat, resulting in higher heat source temperature and greater energy density. It can still maintain effective heating when the main engine is running at low speed or when the ship is moored, improving the reliability of system operation. Deeply coupled with the ship's waste heat recovery system, it further improves the overall energy utilization efficiency and helps IMO carbon intensity compliance.

[0066] Correspondingly, the fluid circulation drive unit 2 is located on the liquid supply pipeline between the heat source supply unit 1 and the fluid rotation transmission device 3, forming the power and control core of the closed-loop circulation circuit. This unit mainly includes a corrosion-resistant circulation pump, a flow regulating valve, a pressure transmitter, and a high-level expansion storage tank.

[0067] The corrosion-resistant circulating pump is preferably a magnetically driven centrifugal pump, with its flow-through components made of 316L stainless steel or fluoroplastics to withstand long-term operation with antifreeze heat transfer media such as ethylene glycol aqueous solution. This pump provides sufficient head to the system, overcoming static pipeline friction and local resistance, and also needs to compensate for the centrifugal potential energy generated by the high-speed rotation of the rotating drum 5, ensuring a stable flow of hot fluid into the heat exchange channel located at the top of the rotating drum.

[0068] The flow regulating valve is an electric proportional regulating valve. Its opening degree is dynamically adjusted by the control unit according to real-time operating conditions, such as inlet and outlet temperature difference, ambient temperature or vibration signal, so as to accurately control the flow rate of hot fluid entering the vortex 5 and realize on-demand heating and energy efficiency optimization.

[0069] The high-level expansion tank is installed at the highest point of the system and connected to the return water line via a connecting pipe. Its internal volume is designed to accommodate the thermal expansion of all fluids within the system over the operating temperature range, such as -25℃ to 95℃. The tank is equipped with an automatic vent valve at the top and a replenishment port at the bottom, providing automatic venting, level maintenance, and system water replenishment functions. This effectively prevents air blockage or negative pressure cavitation, ensuring the pressure stability and long-term reliable operation of the closed-loop circulation system.

[0070] Through the coordinated operation of the above components, the fluid circulation drive unit 2 not only ensures the continuous and stable delivery of the heat medium under complex dynamic conditions, but also provides the execution basis for the intelligent energy-saving control of the system.

[0071] Based on this, in order to reliably introduce and export the heat transfer medium into and out of the high-speed rotating cylinder 5, the present invention provides two sets of fluid rotary joints, located at the upper and lower ends of the cylinder 5 respectively, forming a complete closed-loop circulation path.

[0072] Specifically, the rotating cylinder 5 is rotatably supported on the tower or base 7 by bearings; a central fixing tube 6 is coaxially provided inside the rotating cylinder 5, and the two ends of the central fixing tube 6 are rigidly connected to the tower or base 7 and do not rotate with the rotating cylinder 5.

[0073] The central fixed tube 6 has a liquid supply line inside, one end of which is connected to the fluid circulation drive unit 2. The outlet of the liquid supply line is connected to the inlet of the rotary heat exchange unit 4, which is located on the inner wall or in the interlayer of the rotary cylinder 5, through the first fluid rotary joint 301. The first fluid rotary joint 301 is installed between the rotary cylinder 5 and the central fixed tube 6 to achieve leak-free liquid supply from the stationary liquid supply line to the rotating heat exchange unit.

[0074] The outlet of the swirl heat exchange unit 4 is connected to the second fluid rotary joint, which is installed between the bottom of the swirl 5 and the base 7. The stationary end of the second fluid rotary joint is connected to the return water pipe, which returns to the fluid circulation drive unit 2, thus completing the closed-loop circulation. The base 7 can also be a tower.

[0075] Through the above-mentioned dual-joint structure, the high-temperature heat transfer medium enters the vortex heat exchange unit 4 from the central fixed pipe 6 through the first fluid rotary joint 301, and after heat exchange, it flows out from the other end through the second fluid rotary joint. The entire process achieves bidirectional and leak-free fluid transmission between the rotating and stationary interfaces, which is suitable for large vortex 5 sail systems with long-stroke and high uniformity heat exchange requirements.

[0076] The first fluid rotary joint 301 has an annular structure. One end of it is fixedly connected to the rotary cylinder 5 and communicates with the inlet of the rotary cylinder heat exchange unit 4. The other end faces the central fixed pipe 6 and abuts against its end face to form a rotary mating interface.

[0077] The first fluid rotary joint 301 has an annular cavity 302 inside, which is circumferentially connected to the inlet of the rotary heat exchange unit 4. At the end away from the rotary cylinder 5, the annular cavity 302 has an axial opening groove, which is aligned with and connected to the outlet of the liquid supply pipeline in the central fixed pipe 6, so that the heat transfer medium enters the annular cavity 302 from the stationary liquid supply pipeline through the opening groove, and is then evenly distributed to the rotary heat exchange unit 4.

[0078] Furthermore, to ensure the sealing reliability of each fluid rotary joint under high-speed rotation conditions, an auxiliary sealing structure 8 is provided between the contact end face of the first fluid rotary joint 301 and the central fixed pipe 6. This structure is used to block the leakage path of the heat transfer medium along the rotating interface during the high-speed rotation of the rotary cylinder 5, ensuring that there is no leakage during the liquid inlet process.

[0079] Specifically, at the interface between the first fluid rotary joint 301 and the central fixed pipe 6, two auxiliary sealing structures 8 are provided to block the leakage path of the heat transfer medium along the axial or radial direction.

[0080] The auxiliary sealing structure 8 is an O-ring made of fluororubber FKM or polytetrafluoroethylene PTFE. The two auxiliary sealing structures 8 are respectively embedded in the annular sealing grooves on the upper and lower sides of the opening groove.

[0081] During the rotation of the rotary drum 5, the O-ring seal remains in a static sealing state. Because it is installed between relatively stationary mating surfaces, it effectively prevents fluid from leaking from around the opening groove, thereby improving the overall sealing reliability.

[0082] Through the above structural design, the fluid rotation transmission device 3 can achieve efficient, safe and leak-free transfer of heat energy from a stationary reference frame to a rotating reference frame under complex working conditions such as ship navigation vibration, temperature alternation and high-speed rotation. It is the core guarantee for the inherent safety and maintenance-free operation of this system.

[0083] Preferably, the second fluid rotary joint has a similar structure to the first fluid rotary joint 301.

[0084] Based on this rotating end interface, the swirl heat exchange unit 4 can be integrated into the swirl body 5 in different forms. Two typical implementation methods are provided below.

[0085] In Example 3, the swirl heat exchange unit 4 is arranged in close contact with the inner surface of the swirl cylinder 5 in the form of multi-head spiral coils. Specifically, 2-4 sets of high-temperature and corrosion-resistant pipes, such as 316L stainless steel pipes or cross-linked polyethylene PEX pipes, are wound along the axial direction of the cylinder in a spiral path and fixed to the inner surface of the cylinder wall with heat-resistant adhesives or clamps. Each set of coils is evenly distributed circumferentially to ensure the symmetry and uniformity of heat transfer.

[0086] Each set of spiral coils is connected to an inlet manifold at the beginning and an outlet manifold at the end. The inlet manifold is connected to the liquid inlet channel outlet of the rotating end of the fluid rotary transfer device 3 by welding or flange, while the outlet manifold is sealed and connected to the liquid return channel inlet of the rotating end, thus forming a complete closed heat exchange loop while rotating synchronously with the cylinder.

[0087] This solution is applicable to existing or modified rotary drum 5 structures, requiring no changes to the original drum structure and offering convenient installation. The hot fluid circulates within the coil, and heat is efficiently conducted to the outer surface through the metal or composite material drum wall, maintaining a stable outer wall temperature above 0°C and effectively preventing icing. Furthermore, because the heating element is entirely located inside the drum, it does not disrupt the external aerodynamic shape, avoiding additional wind resistance or structural interference.

[0088] In embodiment 4, the swirl heat exchange unit 4 adopts a flow-guiding jacket structure, which is directly integrated into the double-walled interlayer of the swirl 5. The swirl 5 body is composed of an inner cylinder wall and an outer cylinder wall, with a 5-15 mm annular gap reserved between them. This gap serves as a heat conduction channel, forming a continuous axial flow-guiding jacket. Preferably, the flow-guiding jacket structure has a flow-guiding structure inside, forming a spiral flow channel.

[0089] The inlet and outlet of the jacket are led out through radial pipes and are airtightly connected to the inlet and return channels of the rotating end of the fluid rotary transmission device 3 via rotary welding or sealing flanges. When the system is running, the antifreeze hot fluid flows in from one end of the jacket, flows axially through the entire length of the cylinder, and then flows out from the other end, completing the heat release.

[0090] This structure is integrally formed during the manufacturing stage of the swirl cylinder, offering advantages such as compact design, no additional parts, and strong vibration resistance. Because the heat exchange channels are completely enclosed within the cylinder wall, it not only boasts a clean appearance and excellent aerodynamic performance but also avoids the risk of external mechanical damage. More importantly, the annular jacket provides a larger heat exchange area and a more uniform temperature distribution, effectively eliminating localized cold spots. This makes it particularly suitable for vessels with extremely high anti-icing and de-icing reliability requirements in polar high-humidity and low-temperature environments, such as icebreakers or LNG carriers.

[0091] Based on the effective integration and collaborative operation of the aforementioned units, the control unit, as the command core of the entire system, adopts an electrical control cabinet with a PLC as its core, integrating a frequency converter, a human-machine interface, and a data acquisition module. This unit is electrically connected to various sensors and actuators via cables to achieve automated operation and intelligent monitoring of the system.

[0092] Specifically, the data acquisition module in the control unit includes a sensor subsystem used to acquire real-time system operating status, environmental conditions, and safety parameters, providing a basis for intelligent control decisions. The sensor subsystem specifically includes the following three types of sensors:

[0093] Condition monitoring sensors:

[0094] Temperature transmitters and pressure transmitters are installed at the inlet and outlet of the fluid rotary transmission device 3, respectively, to monitor the inlet and outlet temperatures and pressures of the hot fluid in real time, thereby reflecting the changes in fluid enthalpy and pipeline resistance. At the same time, an infrared non-contact temperature sensor is installed on the top of the rotary drum 5 tower to perform circumferential scanning of the outer wall surface of the rotary drum 5 and provide real-time feedback on the surface temperature distribution, ensuring precise control of the anti-icing and de-icing effect.

[0095] Environmental sensing sensors:

[0096] Ambient temperature and humidity sensors are installed in open areas of the ship's deck away from heat sources to continuously collect ambient temperature and relative humidity data. The control unit calculates an icing risk index based on this data; when the ambient temperature is detected to be below a set threshold and the relative humidity above a set value, the system automatically triggers an early warning and activates anti-icing mode. Preferably, the ambient temperature set threshold is 3°C and the relative humidity set value is 80%.

[0097] Safety monitoring sensors:

[0098] A high-sensitivity vibration acceleration sensor is installed on the bearing seat of the rotating drum 5 or the tower base 7 to monitor the vibration amplitude and frequency characteristics of the rotating drum 5 in real time. Once dynamic imbalance is caused by local icing, the abnormality can be identified in time. In addition, an electromagnetic flow meter is installed on the main pipeline of the circulation loop to monitor the actual flow rate of the fluid, determine whether the pump is working properly, and whether there is blockage or leakage in the pipeline, thereby ensuring the long-term stable operation of the system.

[0099] By integrating the aforementioned multi-dimensional sensor information, the data acquisition module provides the control unit with a comprehensive and reliable operational data foundation, supporting the system to achieve intelligent and adaptive anti-icing and de-icing control strategies.

[0100] 5.2 Control Logic and Strategy

[0101] The control unit incorporates multiple closed-loop control logics, specifically including the following operating modes:

[0102] Warning and anti-icing modes:

[0103] When the environmental sensing sensor detects that the outside temperature is lower than the set threshold and the relative humidity is higher than the set value, the system automatically enters the anti-icing standby state. The PLC commands the fluid circulation drive unit 2 to start, and controls the circulation pump to operate at a low frequency / low flow rate through the frequency converter, maintaining the wall temperature of the rotating drum 5 slightly above the freezing point, and preventing ice nuclei from adhering to the drum wall surface with extremely low energy consumption.

[0104] Powerful de-icing mode:

[0105] When the temperature sensor detects that the temperature in a certain area of ​​the cylinder wall is below 0℃, or the vibration sensor detects that the vibration amplitude of the rotating drum 5 exceeds the safety threshold, the system immediately switches to the powerful de-icing mode. The PLC commands the regulating valve to open fully and controls the circulating pump to operate at full load, inputting high-temperature fluid at maximum flow rate into the rotating drum heat exchange unit 4. At the same time, the system performs PID regulation based on the temperature difference between the inlet and outlet water to ensure rapid heat transfer to melt the bonding interface between the ice layer and the cylinder wall, and uses the centrifugal force generated by the rotation of the rotating drum 5 to throw off the ice.

[0106] The logic of constant temperature and energy efficiency optimization:

[0107] During system operation, the control unit calculates the temperature difference between the fluid inlet and outlet in real time. If the temperature difference is too small, the PLC automatically reduces the pump speed to save energy; if the temperature difference is too large, the PLC automatically increases the pump speed to increase heat flux, thereby achieving on-demand heating and improving the overall energy efficiency of the system.

[0108] Fault protection and purging logic:

[0109] Leakage protection: If the pressure transmitter detects an abnormal drop in pipeline pressure, the system will automatically stop the pump, trigger an alarm, and close the heat source valve to prevent further losses.

[0110] Shutdown and purging: When the system receives a "shutdown" command or the ambient temperature rises back to a safe range, the control unit executes the purging procedure: First, the liquid supply valve on the heat source side is closed, then the solenoid valve of the purging subsystem is opened, and compressed air is used to push the residual fluid in the pipeline and inside the vortex 5 back into the storage tank. After the pressure sensor confirms that the pipeline is purged, the system is completely shut down to prevent the pipeline from freezing and cracking.

[0111] Through the detailed sensor configuration and multi-loop control logic described above, the control unit of this invention not only achieves intelligent anti-icing and de-icing of the surface of the rotary drum 5, but also provides comprehensive safety protection and energy-saving optimization functions. Whether it's anti-icing requirements in low-temperature environments or powerful de-icing tasks under extreme conditions, this system can efficiently handle the situation, ensuring the safety and reliability of ships navigating in cold regions.

[0112] This invention also provides a method for using a rotary drum sail waste heat anti-icing system based on a fluid rotary joint, comprising the following specific steps:

[0113] S1: System Initialization

[0114] Perform a comprehensive initialization check before system startup:

[0115] Expansion tank level: Confirm that the liquid level in the expansion tank is within the normal range to ensure that the system has sufficient expansion space and replenishment capacity;

[0116] Pipeline valve status: Check that all pipeline valves are in the correct position and ensure there are no blockages or abnormalities;

[0117] Electrical connections: Check that the electrical connections between each sensor, actuator and control unit are secure and reliable to avoid system failure due to poor contact;

[0118] Leak detection: Confirm that there are no leaks in the system piping and interfaces through pressure testing or visual inspection.

[0119] S2: Environmental Monitoring

[0120] The intelligent control unit collects and analyzes the following environmental parameters in real time:

[0121] Ambient temperature and humidity: The current outside temperature and relative humidity data are obtained through temperature and humidity sensors installed in the open area of ​​the deck;

[0122] Cylinder wall temperature: The outer wall surface of the rotating cylinder 5 is scanned using an infrared non-contact temperature sensor to obtain the temperature distribution on the cylinder wall surface;

[0123] Vibration data: The vibration of the support structure of the rotating drum 5 is monitored by a high-sensitivity vibration acceleration sensor to determine whether there is dynamic imbalance caused by icing.

[0124] S3: Anti-icing judgment

[0125] The intelligent control unit automatically enters anti-icing mode when it detects the following conditions:

[0126] When the ambient temperature is ≤2℃ and the relative humidity is ≥70%, the system assumes a risk of icing and automatically starts the circulation pump, operating at low frequency and low flow rate to maintain the wall temperature of the vortex drum 5 within the range of 2–5℃, preventing ice nuclei from adhering to the drum wall surface. This mode consumes very little energy and effectively prevents icing.

[0127] S4: De-icing Trigger

[0128] The system will switch to powerful de-icing mode if any of the following occurs:

[0129] Vibration amplitude exceeds the set threshold: This indicates that eccentric icing has formed, leading to dynamic imbalance of the cylinder;

[0130] If the local temperature remains below 0℃ for 5 minutes, it indicates that ice has adhered. At this point, the PLC commands the regulating valve to fully open, controlling the circulating pump to operate at full load, inputting high-temperature fluid at maximum flow rate into the rotary heat exchange unit 4. Simultaneously, PID control is applied based on the inlet and outlet water temperature difference to ensure rapid heat transfer to melt the interface between the ice and the cylinder wall, and the centrifugal force generated by the rotation of the rotary drum 5 is used to detach the ice. The system will continue to run until the vibration returns to normal and the temperature becomes uniform.

[0131] S5: Shutdown Protection

[0132] When the ship is stopped or the ambient temperature remains consistently above 5°C for 1 hour, the system enters shutdown and purging mode.

[0133] Turn off the circulation pump: First, stop the circulation of the hot fluid to prevent heat waste;

[0134] Open the compressed air valve: Use a marine compressed air source to purge the coil with positive pressure for 3-5 minutes to completely remove residual liquid and prevent the pipeline from freezing and cracking in low-temperature environments.

[0135] S6: System Standby

[0136] After purging is complete, all actuators are shut down, and the system enters a low-power standby state.

[0137] Continuously monitor environmental parameters: keep ambient temperature and humidity sensors operational and ready to respond to new startup commands at any time;

[0138] Preparing for the next startup: Once a drop in ambient temperature or an increase in humidity is detected, the system can quickly resume operation, ensuring the continuity of anti-icing function around the clock.

[0139] This system utilizes existing waste heat resources on ships and achieves efficient and safe heat transfer to rotating components through a highly reliable fluid rotary joint. Combined with intelligent sensing and adaptive control, it can achieve all-weather, fault-free de-icing in extremely cold environments down to -40°C. Compared with traditional electric heating solutions, energy consumption is reduced by more than 80%, and there is no risk of electric sparks. It is suitable for explosion-proof vessels such as oil tankers and LNG carriers. The entire system has a modular design and can be adapted to single-tube or multi-tube Flettner sail layouts, contributing to the achievement of green shipping and IMO carbon intensity compliance goals.

[0140] In Example 5, the invention was applied to an ocean-going bulk carrier equipped with five 35-meter-high rotary sails to verify its anti-icing and de-icing performance and operational reliability in a real ship environment.

[0141] 1. System Connection

[0142] A DN50 stainless steel pipe is drawn from the high-temperature cylinder liner water outlet of the ship's main engine, passing through a three-way regulating valve and a filter before connecting to the inlet of a corrosion-resistant magnetic circulation pump. The system uses a 40% ethylene glycol aqueous solution as the heat transfer medium, with a freezing point below -25°C, suitable for polar navigation conditions.

[0143] 2. Rotary transmission structure

[0144] A dual-channel rotary joint is installed at the top center support shaft of each of the five swivels. This joint employs a coaxial sleeve design: the inner tube serves as the inlet channel for high-temperature antifreeze, while the outer tube's annular gap serves as the return channel for cooling water. The rotating end is rigidly connected to the outer cylinder of the five swivels, while the stationary end is fixed to the tower, ensuring leak-free heat transfer at speeds of 0–300 rpm.

[0145] 3. Heat exchange structure of the cylinder wall

[0146] The outer shell of the swirl cylinder 5 adopts a double-layer fiberglass sandwich structure with a sandwich thickness of 12 mm. Three sets of parallel high-temperature resistant PEX spiral coils are embedded inside. The coils are evenly distributed around the circumference of the cylinder, with the beginning end welded to the liquid inlet of the rotary joint and the end end flowing into the liquid return port, forming a closed circulation loop to ensure that heat is evenly conducted to the entire outer surface.

[0147] 4. Work Process

[0148] Step 1: Start-up and Preheating

[0149] When the ambient temperature sensor detects that the outside temperature is below 3°C and the humidity sensor displays a relative humidity of ≥80%, the PLC control unit determines that there is a risk of icing and automatically issues a start command. The system first adjusts the opening of the three-way regulating valve on the heat source side to 20% and starts the circulation pump at a low frequency of 30 Hz, so that the high-temperature fluid is slowly injected into the pipeline and the jacket of the swirl cylinder 5 to gently preheat the system and avoid thermal stress damage to the materials or seal failure due to sudden heating.

[0150] Step Two: Intelligent De-icing and Energy Efficiency Optimization

[0151] After the system enters stable operation, the PLC collects the inlet and outlet liquid temperatures in real time, calculates the temperature difference ΔT = T_in− T_out, and executes the following closed-loop control logic:

[0152] If ΔT < 2℃, it indicates that the heat exchange efficiency is too low or the flow rate is too fast. The PLC will automatically reduce the circulation pump frequency, extend the fluid residence time, improve the heat exchange efficiency and reduce power consumption.

[0153] If ΔT > 10℃, it indicates that the heat load on the cylinder wall is too high and there is a risk of re-icing. The PLC will automatically increase the pump frequency and increase the heat flux to maintain the anti-icing effect.

[0154] Meanwhile, the vibration sensor continuously monitors the dynamic balance of the rotary drum 5. Once the vibration amplitude exceeds 0.5 mm / sRMS, the system immediately prioritizes entering the powerful de-icing mode: fully opening the regulating valve, running the circulating pump at full frequency, and temporarily disabling the temperature difference control logic until the vibration returns to normal, ensuring navigation safety.

[0155] Step 3: Fault Monitoring and Active Protection

[0156] The system monitors pipeline pressure throughout the entire process. If the pressure transmitter detects a sudden drop in pressure exceeding 0.1 MPa within 30 seconds, the PLC immediately executes an emergency shutdown: cutting off the power to the circulating pump, closing the heat source valve, and triggering an audible and visual alarm to prevent high-temperature media leakage from causing equipment damage or personal injury.

[0157] Step 4: Shutdown, purging, and emptying

[0158] When the ship leaves the ice zone, the ambient temperature remains above 5°C for one hour, or a manual shutdown command is received, the system automatically executes the purging procedure:

[0159] Close the electric valve on the heat source side to stop heating;

[0160] Open the solenoid valve to introduce 7 bar marine compressed air, which will push the residual liquid in the coil and pipeline back to the bottom storage tank through the return pipe.

[0161] The venting status is determined by a pressure sensor at the end of the return water pipe—when the pressure stabilizes at 0.6–0.7 MPa for 2 minutes, it is determined that the liquid has been completely drained.

[0162] Close the gas valve and main power supply to complete the dry shutdown.

[0163] This shutdown protection mechanism completely eliminates the risk of pipeline or vortex jacket rupture caused by the freezing and expansion of residual liquid in low-temperature environments, significantly improving the long-term reliability of the system in high-latitude sea areas.

[0164] This embodiment demonstrates that the system requires no additional electric heating device, relying entirely on the ship's waste heat to achieve all-weather intelligent anti-icing and de-icing. Compared to traditional electric slip ring heating solutions, energy consumption is reduced by more than 80%, there is no risk of electric sparks, and it is suitable for explosion-proof scenarios such as oil tankers and LNG carriers; the modular design supports flexible configuration of single or multiple cylinders, contributing to the achievement of green shipping and IMO EEEXI / CII compliance goals.

[0165] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A rotary drum de-icing system based on a fluid rotary joint, comprising a base (7) and a rotary drum (5) disposed on the base (7), characterized in that, The heat source supply unit (1) has its input end connected to the water circulation loop of the ship's main engine cylinder liner or the hot water well outlet of the waste gas boiler, which is used to extract waste heat from the ship and provide high-temperature heat transfer fluid. The fluid circulation drive unit (2) is located downstream of the heat source supply unit (1) and includes a corrosion-resistant circulation pump, a flow regulating valve, a pressure transmitter and a high-level expansion tank, used to drive the heat transfer fluid circulation and maintain system pressure stability. The fluid rotation transmission device (3) includes a first fluid rotation joint (301) located at the upper end of the rotating cylinder (5) and a second fluid rotation joint located at the lower end of the rotating cylinder (5); A rotary heat exchange unit (4) is integrated into the inner wall or interlayer of the rotary cylinder (5). Its inlet is connected to the first fluid rotary joint (301), and its outlet is connected to the second fluid rotary joint, forming a complete closed heat exchange circuit. The rotary heat exchange unit (4) is a multi-head spiral coil, consisting of 2-4 sets of high-temperature resistant PEX tubes or 316L stainless steel tubes evenly distributed around the circumference of the rotary cylinder (5). The rotary cylinder (5) has a coaxially arranged central fixed tube (6) inside. The first fluid rotary joint (301) is located between the central fixed tube (6) and the rotary cylinder (5) to introduce the heat-carrying fluid from the supply pipe in the central fixed tube (6) into the rotary cylinder (5). The first fluid rotary joint (301) is an annular structure. The first fluid rotary joint (301) has an annular cavity (302) inside and an opening groove at the end away from the rotary cylinder (5), which is aligned and connected to the liquid supply pipeline outlet in the central fixed pipe (6). At the interface between the first fluid rotary joint (301) and the central fixed pipe (6), there are two auxiliary sealing structures (8) to block the leakage path of the heat transfer medium along the axial or radial direction under high-speed rotation conditions. The second fluid rotary joint is located between the bottom of the rotary cylinder (5) and the base (7) to discharge the heat exchanged fluid. The control unit is electrically connected to the sensors and actuators in each unit and is used to automatically switch between anti-icing, de-icing and shutdown modes according to the environment and operating status. The control unit is configured to execute the following control logic: When the ambient temperature is ≤3℃ and the relative humidity is ≥80%, start the circulation pump to run at low frequency, maintain the wall temperature of the rotary drum (5) at 2–5℃, and enter the anti-icing mode; When the vibration amplitude exceeds 0.5 mm / s RMS or the local cylinder wall temperature is below 0℃ for 5 minutes, switch to the powerful de-icing mode, fully open the flow regulating valve and run the circulation pump at full frequency; The pump frequency is dynamically adjusted based on the temperature difference ΔT between the inlet and outlet water: if ΔT < 2℃, the frequency is reduced to save energy; if ΔT > 10℃, the frequency is increased to enhance heating.

2. The rotary sail de-icing system based on a fluid rotary joint according to claim 1, characterized in that, The heat source supply unit (1) is connected to the high-temperature outlet of the ship's main engine cylinder liner water circulation loop through a temperature control valve group, or the heat source supply unit (1) is directly connected to the hot water well outlet of the waste gas boiler.

3. The rotary sail de-icing system based on a fluid rotary joint according to claim 1, characterized in that, The control unit is connected to the following sensor subsystems: The status monitoring sensor includes a temperature transmitter and a pressure transmitter installed at the inlet and outlet of the fluid rotary transmission device (3), and an infrared non-contact temperature sensor installed on the top of the rotary drum (5). Environmental sensing sensors, including ambient temperature and humidity sensors for the open deck area; Safety monitoring sensors include a vibration acceleration sensor on the base (7) and a flow meter in the pipeline.

4. The rotary sail de-icing system based on a fluid rotary joint according to claim 1, characterized in that, It also includes a purge and venting subsystem, which includes an electromagnetic valve and a compressed air source. When the machine is stopped, the control unit controls the opening of the subsystem to press the residual fluid in the pipeline and the inside of the rotary drum (5) back into the storage tank to prevent freezing at low temperature.

5. The rotary sail de-icing system based on a fluid rotary joint according to claim 1, characterized in that, The heat transfer fluid is an ethylene glycol-water mixture with a freezing point not higher than -25°C.

6. A control method for a rotary drum sail de-icing system based on a fluid rotary joint, characterized in that, The rotary sail de-icing system based on a fluid rotary joint according to any one of claims 1-5 includes the following steps: S1: System initialization, check liquid level, valve status and leakage; S2: Real-time acquisition of ambient temperature and humidity, cylinder wall temperature and vibration data; S3: If the ambient temperature is ≤2℃ and the humidity is ≥70%, activate the anti-icing mode; S4: If abnormal vibration or local icing is detected, switch to powerful de-icing mode; S5: When shutting down, perform compressed air purging for 3–5 minutes to completely drain the liquid; S6: Enters low-power standby mode and continuously monitors environmental parameters.

7. The control method for the rotary sail de-icing system based on a fluid rotary joint according to claim 6, characterized in that, In step S5, the purging pressure is 0.3–0.5 MPa. After purging is completed, the pressure sensor confirms that there is no liquid residue in the pipeline, and then the system power is turned off to achieve dry shutdown.

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