CN116001992A - Marine floating type clean energy production and biological carbon fixing platform - Google Patents

Abstract

An offshore floating clean energy production and biological carbon sequestration platform, the platform is composed of a plurality of triangular basic frames, and the basic frame is formed by three vertical axis generator columns and floating body support rods to form an overall triangular basic frame. A deck is laid on one of the basic frames, and cranes, equipment rooms and cleaning co-production modules are arranged on the deck, and cage frames are erected above the rest of the basic frames. The breeding cages are located in the cage frames and move up and down through electric winches. After cleaning the cogeneration module for carbon sequestration, the formed ammonium chloride is supplied to the plankton around the platform to achieve the purpose of carbon sequestration. The invention utilizes its own green energy cycle, is self-sufficient, and improves seawater aquaculture production while sequestering carbon based on green energy. Use the mixed seawater discarded by the ocean thermal power generation system for desalination and subsequent clean energy production and mariculture. Clean energy and by-products can also be used for carbon sequestration, reducing operating costs and improving the economic applicability of the system itself.

Description

An Offshore Floating Clean Energy Production and Biological Carbon Sequestration Platform

technical field

The invention relates to the field of ships and ocean engineering, and more specifically, to a green energy-based offshore floating clean energy production and biological carbon sequestration system.

Background technique

At present, ocean carbon storage is mainly supercritical carbon dioxide seabed saline layer storage and deep sea direct injection of carbon dioxide storage. Ocean acidification is caused by the limited space in the seafloor saline layer and the re-release of supercritical carbon dioxide into the seawater due to high-pressure leaks. Deep-sea direct injection of carbon dioxide is directly injecting carbon dioxide at a depth of more than 1,000 meters to dissolve it in seawater, or directly injecting high-density carbon dioxide into the seabed space above 3,000 meters to delay its diffusion in seawater, but this carbon sequestration method It also faces the problem of ocean acidification negatively impacting marine ecosystems, while carbon dioxide dissolved in water may eventually be re-released into the atmosphere and cannot be stored permanently.

Hydrogen and ammonia, as clean energy sources without carbon emissions, are gaining more and more attention in the market, and countries intend to use these two fuels as mainstream new energy sources to replace fossil fuels in the future. However, one of the main reasons restricting the development of hydrogen and ammonia at present is the high production cost, and the global ocean temperature difference energy, offshore wind energy, and offshore solar energy resources are abundant. By using offshore renewable energy to produce clean energy and electricity, while using the clean production The chemical carbon fixation and biological carbon fixation of carbon dioxide by energy can not only make full use of resources, but also realize the stable storage of carbon dioxide.

Contents of the invention

In order to solve the above problems, the present invention provides a green offshore floating clean energy production and biological carbon sequestration system, the technical solution adopted is:

An offshore floating clean energy production and biological carbon sequestration platform, the platform is composed of a plurality of triangular base frames, the base frame has three vertical axis generator columns, and the upper floating body is passed between the three vertical axis generator columns The support rod is fixedly connected to the lower floating body support rod, the upper floating body support rod is located above the sea surface, the lower floating body support rod is located below the sea surface, and the floating body support rod is connected to the vertical axis generator column through a connection pair, A plurality of underwater floating bodies are fixed between the supporting rods of the lower floating body, and the underwater floating bodies are provided with a plurality of ballast tanks and empty tanks. The platform takes the basic frame as a unit, and is composed of multiple basic frames to form an overall platform structure. A vertical-axis generator is fixed on the top of the vertical-axis generator column. The vertical-axis generator generates electricity and stores the electricity in the battery. All units and components in the platform are powered.

The connecting pair has a circular collar, and the collar is set on the vertical axis generator column. A plurality of connecting rings are arranged at equal intervals along the circumferential direction of the collar, and the connecting rings are split connecting rings , the connecting ring is connected to the collar through a transverse connecting shaft, and the connecting ring is connected to the buoy support rod through a longitudinal connecting shaft. The connection structure of the open connection ring can make the support rod of the floating body rotate freely in the horizontal direction and the longitudinal direction relative to the collar, and then multiple basic frames can move relatively, and the support rod of the floating body in the basic frame is relatively vertical to the generator column. It can be movable so that the whole platform exists in an overall state, and when external forces intervene, it can also exist in an individual state of an independent unit. Using the above-mentioned structure can increase the operability and overall anti-fatigue ability of the platform's on-site expansion fan.

A deck is laid on the support bar of the upper floating body of the foundation frame, and a crane, an equipment room, and a cleaning and co-production module are arranged on the deck, and a plurality of The photovoltaic battery panel, the vertical axis generator, the photovoltaic battery panel are connected to the storage battery. The vertical axis generator and photovoltaic panels transmit the generated electricity to the storage battery, which supplies power to the entire platform, providing a stable source of power for the operation of the platform system, and solving the problem of uneven supply and demand of the power generation system and power consumption devices.

The clean cogeneration module is equipped with an OTEC system. The OTEC system discharges part of the mixed seawater into the sea through the mixed seawater pipeline. The mixed seawater discharged into the sea is rich in inorganic nutrients such as nitrates, phosphates, and silicates, which can improve The content of nutrients in the breeding area; the other part is sent to the seawater desalination system, the seawater desalination system generates fresh water and concentrated seawater, the concentrated seawater is sent to the carbon fixation system, and the fresh water is electrolyzed to generate oxygen and hydrogen, and the hydrogen is sent to the ammonia production system to produce nitrogen The system supplies the generated nitrogen to the ammonia production system, the ammonia production system transports the generated liquid ammonia to the OTEC system, and the generated ammonia gas to the carbon fixation system, the carbon fixation system is equipped with a CCS device, so The CCS device mixes the captured CO ₂ with the ammonia gas and the concentrated seawater, and the ammonium chloride formed supplies the surrounding plankton. The surrounding plankton can be eaten by the farmed organisms, and the plankton also play a role in carbon sequestration.

A net cage frame is erected above the rest of the basic frame, and the breeding net cage is located in the net cage frame, and an electric winch is fixed on the top of the net cage frame, and the electric winch is controlled by the control system in the control room. The electric winch is connected with the culture net cage, the cage frame is provided with a vertical guide rail, the culture net cage has a pulley matched with the guide rail, and a walkway is arranged between the culture net cages. aisle. The rest of the basic framework is the breeding area, and there are passages for people to pass between the triangle breeding areas.

The above-mentioned offshore floating clean energy production and biological carbon sequestration platform, furthermore, the OTEC system has an OTEC evaporator, and the OTEC evaporator is connected to a warm water pump and a liquid ammonia pump respectively, and the OTEC evaporator passes through The pipeline is connected with OTEC turbine, OTEC condenser and liquid ammonia pump in turn, and then returns to the OTEC evaporator to form the first circulation network. The OTEC condenser is connected with a cold water pump, which is connected with the ammonia production system in turn through the pipeline. , Seawater desalination system connection, the cold water pipe connected to the cold water pump extends into the seabed, and the warm water pipe connected to the warm water pump communicates with the sea surface. The working fluid ammonia is pumped into the OTEC evaporator through the liquid ammonia pump, and exchanges heat with the warm seawater at 25-27°C drawn from the ocean surface by the warm water pump. After being converted into mechanical energy, electrical energy is generated, where the electrical energy is transported ashore through submarine cables and connected to the grid for power supply. The ammonia gas after the work done by the OTEC turbine enters the OTEC condenser, where it exchanges heat with the cold seawater drawn from the ocean at a depth of 1,000 meters through the cold water pump. The temperature of the seawater here is constant at about 5°C. Become liquid ammonia and enter the next cycle.

In the aforementioned offshore floating clean energy production and biological carbon sequestration platform, further, the OTEC evaporator is connected to a seawater desalination system through pipelines.

The above-mentioned offshore floating clean energy production and biological carbon fixation platform, further, the ammonia production system is connected to the ammonia storage tank and the carbon fixation system through pipelines, and the ammonia storage tank is sequentially connected to the liquid ammonia pump and OTEC evaporation through the pipeline device connection.

In the aforementioned offshore floating clean energy production and biological carbon sequestration platform, further, the deck is provided with a carbon dioxide storage tank, and the CCS device stores the captured carbon dioxide in the carbon dioxide storage tank.

In the aforementioned offshore floating clean energy production and biological carbon sequestration platform, further, the seawater desalination system has a branch pipeline connected to the ammonia production system.

In the aforementioned offshore floating clean energy production and biological carbon sequestration platform, further, the number of the base frames is six, and the six base frames form a hexagonal platform as a whole.

The above-mentioned offshore floating clean energy production and biological carbon sequestration platform, furthermore, a ballast pump and a ballast system are arranged in the equipment room, the ballast pump is connected to the ballast tank, and through the The ballast system controls the ballast pump to adjust the ballast water level in the ballast tank.

In the aforementioned offshore floating clean energy production and biological carbon sequestration platform, further, there are four underwater floating bodies, which are symmetrically fixed on the support rods of the lower floating bodies.

The above-mentioned offshore floating clean energy production and biological carbon sequestration platform, furthermore, a mooring system is fixed on the vertical axis generator column, and the mooring system has a mooring cable, and the mooring cable is free An anchor is connected to the mooring line, and a buoy is also fixed on the mooring line. Floats can improve mooring line shape and force. The anchor is fixed to the seabed to make the platform float in the designated sea area.

The beneficial effects of the present invention are:

1. The floating system converts green energy into electric energy to provide power for the system, which is not only clean and environmentally friendly, but also suitable for self-storage of offshore floating systems. For the seawater temperature difference energy system as an electric energy output unit, about 50% of its internal power consumption is provided by a wind-solar hybrid power generation system, which can greatly improve the efficiency of grid-connected power supply.

2. The clean energy produced by the floating system can be used as a product output, and can also participate in the carbon sequestration of the system.

3. The floating system utilizes the mixed seawater discarded by the ocean temperature difference power generation system for seawater desalination and subsequent clean energy production and mariculture. Clean energy and by-products can also be used for carbon sequestration, reducing operating costs and improving the economy of the system itself applicability.

4. The carbon fixation method of this floating system adopts chemical carbon fixation and biological carbon fixation. Change the previous marine carbon sequestration methods of supercritical carbon dioxide seabed saline layer storage and deep sea direct injection of carbon dioxide storage. The carbon sequestration method adopted by this system is more stable and reliable, will not have an acidification effect on the ocean, and will bring considerable economic benefits at the same time.

Description of drawings

Fig. 1 is a side view structural representation of the present invention;

Fig. 2 is a schematic diagram of the three-dimensional structure of the present invention;

Fig. 3 is a schematic view of the top view structure of the present invention;

Fig. 4 is the structural representation of connection pair;

Fig. 5 is a schematic diagram of the system of the present invention;

Fig. 6 is a schematic diagram of the platform after expanding two wind turbines;

Fig. 7 is the platform schematic diagram after expanding four wind turbines;

Among them: 1-OTEC evaporator, 2-OTEC turbine, 3-OTEC condenser, 4-liquid ammonia pump, 5-cold water pump, 6-warm water pump, 7-ammonia storage tank, 8-nitrogen system, 9-system Ammonia system, 10-battery, 11-seawater desalination system, 12-vertical axis generator column, 13-photovoltaic battery panel, 14-connection pair, 15-net cage frame, 16-culture cage, 17-equipment room, 18 -crane, 19-living building, 21-OTEC system, 22-walkway, 23-deck, 24-mooring cable, 25-float, 26-anchor, 27-underwater floating body, 28-floating body support rod, 29 -carbon dioxide storage tank, 30-control room, 33-warm water pipeline, 34-cold water pipeline, 1401-collar, 1402-connecting ring, 1403-horizontal connecting shaft, 1404-longitudinal connecting shaft.

Detailed ways

The present invention will be further described in conjunction with the accompanying drawings.

As shown in Figures 1 and 2, an offshore floating clean energy production and biological carbon sequestration platform is suitable for deep sea areas with a water depth greater than 800 meters in low latitudes. The platform is composed of six triangular basic frames and is hexagonal in shape The platform and the foundation frame are composed of three vertical axis generator columns. The three vertical axis generator columns are fixedly connected by the upper floating body support rod and the lower floating body support rod. The upper floating body support rod is located above the sea surface, and the lower floating body support rod is located on the sea surface. Below, the support rods of the floating body are connected to the vertical axis generator column through the connecting pair, and a plurality of underwater floating bodies are fixed between the supporting rods of the lower floating body, and the underwater floating bodies have multiple ballast tanks and empty tanks.

The connecting pair has a circular collar, as shown in Figure 4, the collar is set on the vertical axis generator column, and six connecting rings are arranged at equal intervals along the circumferential direction of the collar, the connecting rings are split connecting rings, and the connecting rings pass through The transverse connecting shaft is connected with the collar, and the connecting ring is connected with the support bar of the floating body through the longitudinal connecting shaft. A plurality of photovoltaic panels are fixed on the deck near the column of the vertical-axis generator, and the vertical-axis generator, the photovoltaic panel and the storage battery are connected. The vertical axis generator and photovoltaic panels store the generated electricity in the battery, convert wind energy and solar energy into electrical energy, and store the electrical energy generated by the two unstable energy sources in the battery to provide a stable power source for the operation of the platform system. Solve the problem of uneven supply and demand of power generation systems and power consumption devices.

As shown in Figure 3, a deck is laid on the support rods of the upper floating body of a foundation frame. Cranes, equipment rooms and cleaning and co-production modules are arranged on the deck. Cage frames are arranged above the other five foundation frames. Inside the box frame, an electric winch is fixed on the top of the cage frame, and the electric winch is controlled by the control system in the control room. ), the culture net cage has a pulley matched with the guide rail, and a walkway is arranged between the culture net cages.

As shown in Figure 5, the clean cogeneration module is equipped with an OTEC system. The OTEC system discharges part of the mixed seawater into the sea through the mixed seawater pipeline, and the other part is sent to the seawater desalination system. The seawater desalination system generates fresh water and concentrated seawater, and the concentrated seawater is transported To the carbon fixation system, fresh water is electrolyzed to generate oxygen and hydrogen, and the hydrogen is sent to the ammonia production system. The nitrogen production system supplies the generated nitrogen to the ammonia production system. Carbon system, the carbon fixation system has a CCS device, and the CCS device mixes the captured CO ₂ with ammonia gas and concentrated seawater, and the ammonium chloride formed supplies the surrounding plankton.

The OTEC system is a technology that converts electrical energy using the thermal gradient available in the ocean, and is divided into closed cycle, open cycle and mixed cycle systems according to the process. Because this system is used in offshore floating structures, the overall space is limited, so a closed circulation system with a more compact overall device is adopted. The working fluid of the OTEC system is ammonia, which has better physical performance, price and system maturity. The OTEC closed cycle system based on ammonia working fluid is composed of OTEC evaporator, OTEC turbine, OTEC condenser, ammonia storage tank, liquid ammonia pump, warm water pump and cold water pump. The working fluid ammonia is pumped into the OTEC evaporator through the liquid ammonia pump, and exchanges heat with the warm seawater drawn from the ocean surface through the warm water pump. The temperature of the seawater here is 25-27°C. , to drive the turbine to convert the internal energy into mechanical energy to generate electrical energy, where the electrical energy is transmitted to the shore through submarine cables and connected to the grid for power supply. The ammonia gas after the work done by the OTEC turbine enters the OTEC condenser, where it exchanges heat with the cold seawater drawn from the ocean at a depth of 1,000 meters through the cold water pump. The temperature of the seawater here is constant at about 5°C. Become liquid ammonia and enter the next cycle. The liquid ammonia in the ammonia storage tank enters the circulation system as a supplementary working medium for the system. The warm seawater and cold seawater after heat exchange in the OTEC evaporator and OTEC condenser are mixed. At this time, the seawater temperature is about 18°C, and the medium-temperature seawater enters the seawater desalination system and the subsequent carbon fixation system. The seawater desalination process can adopt thermal process or membrane process, and the products of seawater desalination are fresh water and concentrated seawater (containing high concentration of sodium chloride). A part of the fresh water produced can be exported as a product to provide a source of fresh water for the floating unit. The other part produces hydrogen and oxygen through electrolysis, and its formula is as follows:

2H ₂ O→2H ₂ (g)+O ₂ (g) (energized)

Part of the hydrogen and oxygen is output as products, and the other part participates in nitrogen production and carbon fixation systems. Also considering the limited overall space of the floating unit, the nitrogen production system should adopt the pressure swing adsorption nitrogen production method (PSA) to separate the nitrogen in the air. Part of the generated nitrogen is output as a product, and the other part is mixed with the hydrogen generated by the system to synthesize ammonia using the Haber method. The basic formula is as follows:

The cold sea water pumped out of the OTEC system can be used as the cooling water source of the ammonia production system. Part of the liquid ammonia separated by the Haber ammonia production process enters the ammonia storage tank as a supplementary working fluid for the OTEC system and is output as a product, and the other part is gasified to form Ammonia enters the carbon sequestration system. The gasified ammonia gas and the carbon dioxide gas captured by CCS and transported to the floating system are successively passed into the concentrated seawater produced by the seawater desalination system, and the three are mixed to undergo a chemical reaction to produce sodium bicarbonate crystal precipitation and ammonium chloride. The formula is as follows :

NaCl+NH ₃ +H ₂ O+CO ₂ →NaHCO ₃ ↓+NH ₄ Cl

After the sodium bicarbonate crystals are separated from the solution, they can be injected into seawater below 1000 meters through pipelines for storage or sealed in containers. Factors affecting the storage of sodium bicarbonate in seawater include pH value and seawater density (seawater temperature), deep seawater pH value Between 7.5 and 7.8, sodium bicarbonate mainly exists in seawater as sodium ions and bicarbonate ions, and is relatively stable (according to the Bjerrum carbonate system diagram). And in the deep water layer below 1000 meters, the water temperature is low (2-5 ℃), and the density is almost constant. Under the condition that the temperature and PH value of the surrounding seawater are stable, inject sodium bicarbonate crystals into the deep water layer below 1000 meters. Using the density difference between it and seawater, the dissolved high-concentration sodium bicarbonate solution will sink to the seabed under the influence of gravity. , to achieve the role of carbon fixation, which is chemical carbon fixation. Biological carbon sequestration is the cultivation of marine organisms with high inorganic carbon content in the body. It uses the characteristics of long cycle of inorganic carbon in nature to achieve the purpose of carbon sequestration. Ammonium chloride, the product of chemical carbon fixation, is used as nitrogen fertilizer to supply the plankton around the floating system, which can effectively increase the plankton capacity in the surrounding sea area, and provide sufficient food sources for the cultured gastropods and bivalves. The carbon sequestration effect can also be achieved by the sinking of organisms to the bottom of the sea after death. Gastropods and bivalves can be abalones, conchs, oysters, scallops, etc. with high economic benefits. The inorganic components in the shells of these two types of organisms - calcium carbonate content accounts for about 90%. The body can sink into the seabed for carbon sequestration, or be used to make handicrafts, ornaments, building materials, etc. A small part of the medium and low temperature seawater discharged from the OTEC system is used for mariculture. The cold water pumped from the deep sea contains rich inorganic nutrients such as nitrate, phosphate, and silicate, which can increase the content of nutrients in the farming area. The oxygen produced by freshwater electrolysis can increase the oxygen content of seawater in the culture area and improve the survival rate of organisms. The marine organisms cultured are gastropods and bivalves, which can be abalones, conchs, oysters, scallops, etc. with high economic benefits. At the same time as food, the remaining shells can be sunk into the seabed for carbon sequestration, or transported ashore for making handicrafts, ornaments, building materials, etc., to achieve the purpose of carbon sequestration.

The invention utilizes its own green energy cycle, is self-sufficient, and improves seawater aquaculture production while sequestering carbon based on green energy. Converting green energy into electric energy to power the system is not only clean and environmentally friendly, but also suitable for self-storage of off-shore floating systems. For the seawater temperature difference energy system as an electric energy output unit, about 50% of its internal power consumption is provided by a wind-solar hybrid power generation system, which can greatly improve the efficiency of grid-connected power supply. The ammonia produced by the invention can be output as a product, and can also participate in the carbon fixation of the system, so as to solve the problems of carbon peaking and carbon neutralization from two aspects. Use the mixed seawater discarded by the ocean thermal power generation system for desalination and subsequent clean energy production and mariculture. Clean energy and by-products can also be used for carbon sequestration, reducing operating costs and improving the economic applicability of the system itself. The present invention adopts two methods of chemical carbon fixation and biological carbon fixation, and changes the previous ocean carbon fixation methods of supercritical carbon dioxide seabed saline layer storage and deep sea direct injection of carbon dioxide for storage. The carbon sequestration method adopted by this system is more stable and reliable, will not have an acidification effect on the ocean, and will bring considerable economic benefits at the same time.

At the same time, this platform takes advantage of the small radius of gyration of the vertical axis wind turbine and the characteristics of compact wind field. After the on-site operation, it can increase the grid-connected power supply by expanding the number of vertical axis wind turbines according to the needs of the grid, as shown in Figure 6 and Figure 7. 2 and 4 are the top view schematic diagrams after the expansion of two and four wind turbines respectively. The expansion of the wind turbines is realized by connecting the male buckle on the support rod of the floating body with the female buckle of the docking ring on the vertical axis generator cylindrical buoy.

Claims (7)

1. An offshore floating clean energy production and biological carbon fixation platform, which is characterized in that: the platform consists of a plurality of triangular foundation frames, wherein the foundation frames are provided with three vertical shaft generator columns, the three vertical shaft generator columns are fixedly connected through upper floating body supporting rods and lower floating body supporting rods, the upper floating body supporting rods are positioned above the sea surface, the lower floating body supporting rods are positioned below the sea surface, the floating body supporting rods are connected with the vertical shaft generator columns through connecting pairs, a plurality of underwater floating bodies are fixed between the lower floating body supporting rods, and the underwater floating bodies are provided with a plurality of ballast tanks and empty tanks;

the connecting pair is provided with a circular lantern ring, the lantern ring is sleeved on the vertical shaft generator column, a plurality of connecting rings are arranged at equal intervals along the circumference of the lantern ring, the connecting rings are open connecting rings, the connecting rings are connected with the lantern ring through transverse connecting shafts, and the connecting rings are connected with the floating body supporting rods through longitudinal connecting shafts;

a deck is paved on the upper floating body supporting rod of the foundation frame, a crane, an inter-equipment and a clean co-production module are arranged on the deck, a plurality of photovoltaic cell panels are fixed on the deck and close to the vertical shaft generator column, and the vertical shaft generator and the photovoltaic cell panels are connected with a storage battery;

the clean CO-production module is provided with an OTEC system, the OTEC system discharges part of mixed seawater into the sea through a mixed seawater pipeline, the other part of the mixed seawater is conveyed to a seawater desalination system, the seawater desalination system generates fresh water and concentrated seawater, the concentrated seawater is conveyed to a carbon sequestration system, the fresh water is electrolyzed to generate oxygen and hydrogen, the hydrogen is conveyed to an ammonia production system, the nitrogen production system supplies generated nitrogen to the ammonia production system, the ammonia production system conveys generated liquid ammonia to the OTEC system, generated ammonia is conveyed to the carbon sequestration system, the carbon sequestration system is provided with a CCS device, and the CCS device captures CO ₂ Mixing with the ammonia gas and the concentrated seawater, and supplying formed ammonium chloride to surrounding plankton;

the rest the net cage frame is erect to the foundation frame top, and the aquaculture net cage is located in the net cage frame, net cage frame top is fixed with electric winch, electric winch passes through the control system control in the control room, and the hawser is walked around electric winch with the aquaculture net cage is connected, be provided with vertical guide rail on the net cage frame, the aquaculture net cage have with guide rail matched with pulley, be provided with the pavement between the aquaculture net cage.

2. The offshore floating clean energy production and biosolid carbon platform of claim 1 wherein: a carbon dioxide storage tank is arranged on the deck, and the CCS device stores the captured carbon dioxide in the carbon dioxide storage tank.

3. The offshore floating clean energy production and biosolid carbon platform of claim 1 wherein: the sea water desalting system is connected with an ammonia making system through a branch pipeline.

4. The offshore floating clean energy production and biosolid carbon platform of claim 1 wherein: the number of the base frames is six, and six base frames form a platform which is integrally hexagonal.

5. The offshore floating clean energy production and biosolid carbon platform of claim 1 wherein: a ballast pump and a ballast system are arranged in the equipment room, the ballast pump is connected with the ballast tank, and the ballast water level in the ballast tank is regulated by controlling the ballast pump through the ballast system.

6. The offshore floating clean energy production and biosolid carbon platform of claim 1 wherein: the number of the underwater floating bodies is four, and the underwater floating bodies are symmetrically fixed on the lower-layer floating body supporting rods.

7. The offshore floating clean energy production and biosolid carbon platform of claim 1 wherein: the vertical axis generator column is fixedly provided with a mooring system, the mooring system is provided with a mooring rope, the free end of the mooring rope is connected with an anchor, and a floater is also fixed on the mooring rope.

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