High-temperature water-glycol heating system for LNG container ships

Abstract

This utility model relates to the field of shipbuilding and provides a high-temperature water-glycol heating system for LNG container ships. It includes a first heater, an input pipe, and an input pump. The heat exchange medium channel of the first heater is connected to a high-temperature hot water generating unit. A second heater is connected in parallel with the first heater, and the heat exchange medium channel of the second heater is connected to a steam pipe on the ship. Utilizing the heat carried out by the circulating cooling water in the main engine cylinder liner of the container ship, the first heater heats the water-glycol. After heating, the circulating water temperature decreases and is cooled before returning to the cylinder liner for recirculation. This system utilizes waste heat while cooling the circulating water, reducing the load on the heat exchanger. The second heater, heated by steam, serves as a backup heating method, thus economically utilizing the ship's waste heat, effectively reducing energy and fuel consumption, and lowering maintenance costs.

Description

Technical Field

[0001] This utility model relates to the field of shipbuilding, specifically to a high-temperature water glycol heating system for LNG container ships. Background Technology

[0002] LNG container ships are green vessels fueled by LNG. Cryogenic liquid LNG is vaporized through the ship's heating and circulation system and then sent to the main engine for combustion, providing propulsion. A common practice in heating and circulation systems is to use a mixture of water and ethylene glycol as the heating medium. This medium has a freezing point of -30°C, effectively preventing icing on the surface of the LNG vaporizer heat exchange tubes and improving heat exchange efficiency. The heated water-ethylene glycol is an excellent heating medium for LNG.

[0003] Before being fed into the heating circulation system, water-glycol needs to be heated to over 90 degrees Celsius to ensure efficient vaporization heat exchange. Currently, onboard ships typically use steam to heat the water-glycol, which then uses the heat to heat the LNG. This process consumes a large amount of steam, is energy inefficient, and is uneconomical. Summary of the Invention

[0004] In order to achieve heating of water-glycol medium and reduce energy consumption, this utility model provides a high-temperature water-glycol heating system for LNG container ships.

[0005] The technical solution adopted by this utility model is as follows:

[0006] A high-temperature water-glycol heating system for LNG container ships includes a first heater, an input pipe, and an input pump. The system is characterized in that the heat exchange medium channel of the first heater is connected to a high-temperature hot water generating unit, and the heat exchange medium after heat exchange in the first heater returns to the high-temperature hot water generating unit; the water-glycol after heat exchange in the LNG vaporization unit is sent to the first heater for heat exchange through the input pipe and the input pump, and the water-glycol after heat exchange is sent to the LNG vaporization unit for heat exchange through the output pipe and the output pump, forming a heat exchange cycle; a second heater is connected in parallel to the first heater, and the heat exchange medium channel of the second heater is connected to a steam pipe on the ship; the water-glycol after heat exchange in the second heater is sent to the LNG vaporization unit for heat exchange through the output pipe and the output pump; the condensate formed after heat exchange of steam in the heat exchange medium channel of the second heater is connected to the condensate piping system via a pipe.

[0007] Furthermore, the high-temperature hot water generating unit includes a main cylinder liner, which is connected to a hot water input pipe and a hot water output pipe. The hot water output pipe supplies heat exchange medium to the first heater and the heat exchanger through an electric proportional three-way valve. The heat exchange medium after heat exchange in the first heater enters the heat exchanger and the hot water pump through a return pipe and the proportional three-way valve. The hot water pump is installed on the hot water input pipe, and the heat exchange medium after heat exchange in the heat exchanger enters the main cylinder liner through the hot water pump and the hot water input pipe.

[0008] Furthermore, a preheater is installed in parallel on the hot water input pipe, and a valve is installed on the pipe between the two joints connecting the hot water input pipe and the preheater. Valves are also installed on the input and output pipes of the preheater.

[0009] Furthermore, the preheater is connected to the main engine cylinder liner via a circulation pipe and a circulation pump.

[0010] Furthermore, an expansion tank is connected to the pipe between the hot water pump and the heat exchanger. The expansion tank is connected to the condensate piping system and the engine room water supply system. A vent pipe is installed on the top of the expansion tank.

[0011] Furthermore, a pressure relief valve and an expansion tank are installed on the output pipeline, and the pressure relief branch of the pressure relief valve is connected to the expansion tank; a nitrogen input and discharge pipe are connected to the top of the expansion tank, and the discharge pipe extends to a safe area above the deck.

[0012] Furthermore, a high-pressure pipe is connected to the output pipe, and high-pressure nitrogen gas flows through the high-pressure pipe.

[0013] After adopting the above technical solution, the beneficial effects of this utility model are as follows:

[0014] This design utilizes the heat carried out by the circulating cooling water in the cylinder liner of the container ship's main engine to heat water-glycol via a first heater. After heating, the circulating water temperature decreases and is cooled before returning to the cylinder liner for recirculation. This process utilizes waste heat while cooling the circulating water, reducing the load on the heat exchanger. The design also includes a second heater that uses steam as a backup heating method. Under normal circumstances, the heat from the cylinder liner circulating water is used to heat the water-glycol, while in emergencies, steam heating is used. This economical use of the ship's waste heat effectively reduces energy and fuel consumption, and lowers maintenance costs. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of a water-glycol heating system.

[0016] Figure 2 This is a system schematic diagram of a high-temperature hot water generation unit.

[0017] In the diagram: 1. First heater, 2. Output pipe, 3. Output pump, 4. High-pressure pipe, 5. Expansion tank, 6. Discharge pipe, 7. Main engine cylinder liner, 8. Hot water input pipe, 9. Hot water output pipe, 10. Heat exchanger, 11. Hot water pump, 12. Electric proportional three-way valve, 13. Three-way valve, 14. Preheater, 15. Circulation pump, 16. Second heater, 17. Expansion tank. Detailed Implementation

[0018] The specific embodiments of this utility model will be further described in detail below with reference to the accompanying drawings:

[0019] like Figure 1 As shown, the high-temperature water glycol heating system for LNG container ships consists of several parts, including a high-temperature water heat exchange unit, a steam heat exchange unit, a high-temperature hot water generating unit that provides heat exchange medium to the high-temperature water heat exchange unit, as well as related pipes, valves, sensors, etc. It is used to heat water glycol to a high temperature and use it for the vaporization of liquid LNG.

[0020] The high-temperature water heat exchange unit consists of a first heater 1, an output pipe 2, and an output pump 3. The heat exchange medium channel of the first heater 1 carries hot water at approximately 90 degrees Celsius generated by the high-temperature hot water generator. This hot water exchanges heat with water glycol within the first heater 1. After the heat exchange, the cooled hot water returns to the high-temperature hot water generator through the pipe for further circulation. The heated water glycol is then sent to the LNG vaporization unit for heat exchange via the output pump 3 and the output pipe 2. The cooled water glycol then returns to the first heater 1 for further heat exchange, forming a heat exchange cycle. A high-pressure pipe 4 is connected to the output pipe 2, and high-pressure nitrogen is supplied through the high-pressure pipe 4. High-pressure nitrogen provides the input pressure, preventing fuel gas from entering the heating system. A pressure relief valve and an expansion tank 5 are installed on the output pipe 2. The pressure relief branch of the pressure relief valve is connected to the expansion tank 5. A nitrogen input and discharge pipe 6 is connected to the top of the expansion tank 5, and the discharge pipe 6 extends to a safe area above the deck.

[0021] The high-temperature hot water generating unit is for recovering and utilizing the waste heat of the main engine cylinder liner. It mainly consists of the main engine cylinder liner 7, which is connected to a hot water inlet pipe 8 and a hot water outlet pipe 9. The hot water, cooled after heat exchange in the first heater 1, is further cooled by heat exchange with seawater in the heat exchanger 10. It is then sent to the main engine cylinder liner 7 through the hot water pump 11 and the hot water inlet pipe 8 to cool the main engine, carry away the heat from the main engine and raise its temperature. The heated hot water is then output through the hot water outlet pipe 9.

[0022] Hot water output pipe 9 supplies hot water to the first heater 1 via electric proportional three-way valve 12 for circulating heating of water glycol, or outputs hot water to hot water input pipe 8. A three-way valve 13 is installed on hot water input pipe 8. The three-way valve 13 controls the hot water sent to the hot water input pipe 8 to be directly sent to the main engine cylinder liner 7 or sent to the heat exchanger 10 for cooling and heat exchange before being sent to the main engine cylinder liner 7.

[0023] A preheater 14 is installed in parallel on the hot water inlet pipe 8. Valves are installed on the pipes between the two joints connecting the hot water inlet pipe 8 and the preheater 14. Valves are also installed on the inlet and outlet pipes of the preheater 14. The preheater 14 is connected to the main engine cylinder liner 7 via a circulation pipe and a circulation pump 15. When the ship is moored and shut down for an extended period, the water inside the preheater 14 is preheated before starting the main engine to ensure the normal operation of the system.

[0024] The steam heat exchange unit mainly consists of a second heater 16, which is connected in parallel with the first heater 1. The heat exchange medium channel of the second heater 16 is connected to the steam pipeline on the ship. The water glycol after heat exchange in the second heater 16 is sent to the LNG vaporization unit for heat exchange through the output pump and output pipeline. The condensate formed after heat exchange of the steam in the heat exchange medium channel of the second heater 16 is connected to the condensate piping system through the pipeline.

[0025] An expansion tank 17 is connected to the pipe between the hot water pump 11 and the heat exchanger 10. The expansion tank 17 is connected to the condensate pipe system and the engine room water supply pipe system as a supplement to the water source. A vent pipe is installed on the top of the expansion tank 17 to discharge the generated exhaust gas and avoid excessive internal pressure.

Claims

1. A high-temperature water-glycol heating system for LNG container ships, comprising a first heater, an inlet pipe, and an inlet pump, characterized in that, The heat exchange medium channel of the first heater is connected to a high-temperature hot water generating unit. The heat exchange medium after heat exchange in the first heater returns to the high-temperature hot water generating unit. The water-glycol after heat exchange in the LNG vaporization unit is sent to the first heater for heat exchange through an input pipe and an input pump. The water-glycol after heat exchange is sent to the LNG vaporization unit for heat exchange through an output pipe and an output pump, forming a heat exchange cycle. The first heater is connected in parallel with a second heater. The heat exchange medium channel of the second heater is connected to the steam pipe on the ship. The water-glycol after heat exchange in the second heater is sent to the LNG vaporization unit for heat exchange through an output pipe and an output pump. The condensate formed after heat exchange of the steam in the heat exchange medium channel of the second heater is connected to the condensate piping system through a pipe.

2. The high-temperature water-glycol heating system for LNG container ships according to claim 1, characterized in that, The high-temperature hot water generating unit includes a main cylinder liner, which is connected to a hot water input pipe and a hot water output pipe. The hot water output pipe supplies heat exchange medium to the first heater and the heat exchanger through an electric proportional three-way valve. The heat exchange medium after heat exchange in the first heater enters the heat exchanger and the hot water pump through a return pipe and the proportional three-way valve. The hot water pump is installed on the hot water input pipe. The heat exchange medium after heat exchange in the heat exchanger enters the main cylinder liner through the hot water pump and the hot water input pipe.

3. The high-temperature water-glycol heating system for LNG container ships according to claim 2, characterized in that, A preheater is installed in parallel on the hot water input pipe, and a valve is installed on the pipe between the two joints connecting the hot water input pipe and the preheater. Valves are also installed on the input and output pipes of the preheater.

4. The high-temperature water-glycol heating system for LNG container ships according to claim 3, characterized in that, The preheater is connected to the main engine cylinder liner via a circulation pipe and a circulation pump.

5. The high-temperature water-glycol heating system for LNG container ships according to claim 2, characterized in that, An expansion tank is connected to the pipe between the hot water pump and the heat exchanger. The expansion tank is connected to the condensate piping system and the engine room water supply system. A vent pipe is installed on the top of the expansion tank.

6. The high-temperature water-glycol heating system for LNG container ships according to claim 1, characterized in that, The output pipeline is equipped with a pressure relief valve and an expansion tank. The pressure relief branch of the pressure relief valve is connected to the expansion tank. The top of the expansion tank is connected to a nitrogen input and discharge pipe, and the discharge pipe extends to a safe area above the deck.

7. The high-temperature water-glycol heating system for LNG container ships according to claim 1, characterized in that, A high-pressure pipe is connected to the output pipe, and high-pressure nitrogen gas flows through the high-pressure pipe.

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