A marine main engine cylinder liner water and exhaust waste heat recovery power generation system and control method

Abstract

The application discloses a kind of ship main engine cylinder liner water and waste heat recovery power generation system, containing ship main engine, exhaust gas composite boiler, energy storage system, cylinder liner water heater, water generator, degassing chamber, expansion tank, cylinder liner cooling water pump, temperature control valve, organic rankine cycle system and exhaust gas supercharger.The application can not only effectively recover the waste heat in the cylinder liner water of ship main engine, but also recover the excess waste heat through steam through the exhaust gas boiler, and utilize the waste heat in stages by using evaporators of different pressures, efficiently convert the internal energy of waste heat into electrical energy by organic rankine cycle.

Description

Technical Field

[0001] This invention relates to a power generation system and control method, particularly a power generation system and control method for recovering waste heat from ship engine cylinder liner water and exhaust gas, belonging to the field of marine technology. Background Technology

[0002] Faced with the dual challenges of emission reduction pressure and energy transition, shipping, as a traditional mode of transportation, is experiencing a surge in global ship numbers and stringent emission regulations from the International Maritime Organization and the European Union. Reducing greenhouse gas emissions throughout the ship's lifecycle and improving energy efficiency have become hot research topics. The performance of marine diesel engines has reached approximately 50%, with limited room for significant improvement, and some heat is discharged with cylinder liner water and exhaust gases. Currently, most ships are equipped with waste heat boilers and water makers to recover this heat; however, these methods are insufficient for effective waste heat recovery, with some heat still wasted, especially during summer operating conditions. Current research and inventions propose using organic Rankine cycle power generation technology to recover ship waste heat. This technology uses a low-boiling-point organic working fluid, heated by a low-to-medium grade heat source (such as cylinder liner water waste heat, steam, or exhaust gas), to generate high-pressure steam for cyclic power generation. It features simple structure and convenient operation, making it the most promising low-to-medium temperature waste heat power generation technology.

[0003] However, existing marine organic Rankine cycle waste heat recovery power generation technology still has some shortcomings, such as the inability to effectively couple and utilize the waste heat of cylinder liner water and steam, the fluctuation of output power due to heat source fluctuations, the distribution and structural design optimization of cylinder liner water entering the water maker and organic Rankine cycle system, and the heat source mismatch caused by using the same evaporation pressure for different heat source temperatures. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a power generation system and control method for recovering heat from water and exhaust gas in the cylinder liner of a ship's main engine, thereby recovering heat from the water and exhaust gas in the cylinder liner of the ship's main engine and achieving stable power generation.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0006] A marine main engine cylinder liner water and exhaust gas waste heat recovery power generation system includes a marine main engine, an exhaust gas combined boiler, an energy storage system, a cylinder liner water heater, a water maker, a degassing chamber, an expansion tank, a cylinder liner cooling water pump, a temperature control valve, an organic Rankine cycle system, and an exhaust gas booster. The cylinder liner water outlet of the marine main engine is connected to the inlet of the cylinder liner water heater, the outlet of the cylinder liner water heater is connected to one end of the water maker, the other end of the water maker is connected to the inlet of the degassing chamber, and the exhaust outlet of the degassing chamber is connected to the inlet of the expansion tank. The expansion tank's first... One outlet is connected to the inlet of the central cooling freshwater system, the outlet of the central cooling freshwater system is connected to the inlet of the temperature control valve, the outlet of the degassing chamber is connected to the second outlet of the expansion tank, the outlet of the temperature control valve, and one end of the cylinder liner cooling water pump, the other end of the cylinder liner cooling water pump is connected to the cylinder liner water inlet of the main engine, the exhaust gas outlet of the main engine is connected to the inlet of the exhaust gas turbocharger, the outlet of the exhaust gas turbocharger is connected to the inlet of the exhaust gas combined boiler, and the steam loop of the exhaust gas combined boiler is connected to the organic Rankine cycle system.

[0007] Furthermore, the organic Rankine cycle system includes a low-pressure evaporator, a high-pressure evaporator, a low-pressure turbine, a low-pressure generator, a high-pressure turbine, a high-pressure generator, a condenser, a low-pressure working fluid pump, a high-pressure working fluid pump, a thermal oil heater, a thermal oil pump, and a central cooling freshwater pump. The outlet of the central cooling freshwater system is connected to the inlet of the central cooling freshwater pump. The inlet of the condenser is connected to the outlet of the central cooling freshwater pump. The outlet of the condenser is connected to the inlet of the central cooling freshwater system. The air inlet of the condenser is connected to the air outlets of the low-pressure turbine and the high-pressure turbine. The outlet of the condenser is connected to one end of the low-pressure working fluid pump and one end of the high-pressure working fluid pump. One end of the pump is connected to the working fluid inlet of the low-pressure evaporator, the other end of the working fluid outlet of the low-pressure evaporator is connected to the air inlet of the low-pressure turbine, the low-pressure turbine is connected to the low-pressure generator, the other end of the pump is connected to the working fluid inlet of the high-pressure evaporator, the working fluid outlet of the high-pressure evaporator is connected to the air inlet of the high-pressure turbine, the high-pressure turbine is connected to the high-pressure generator, the high-pressure generator and the low-pressure generator are connected to the energy storage system, the heat transfer oil outlet of the high-pressure evaporator is connected to one end of the heat transfer oil pump, the other end of the heat transfer oil pump is connected to the heat transfer oil inlet of the heat transfer oil heater, and the heat transfer oil outlet of the heat transfer oil heater is connected to the heat transfer oil inlet of the high-pressure evaporator.

[0008] Furthermore, the organic Rankine cycle system also includes a pressure-controlled three-way valve and a pressure sensor. The pressure sensor is installed on the waste gas combined boiler. The steam outlet of the waste gas combined boiler is connected to the inlet of the pressure-controlled three-way valve. The first outlet of the pressure-controlled three-way valve is connected to the steam inlet of the waste gas combined boiler and the steam outlet of the thermal oil heater. The second outlet of the pressure-controlled three-way valve is connected to the steam inlet of the thermal oil heater.

[0009] Furthermore, it also includes a manual valve, one end of which is connected to the external steam supply end, and the other end of which is connected to the air inlet of the cylinder liner water heater, and the air outlet of the cylinder liner water heater is connected to the external steam return end.

[0010] Furthermore, it also includes a first temperature sensor, a second temperature sensor, and a third temperature sensor. The first and second temperature sensors are located at the water outlet of the ship's main engine cylinder liner, and the third temperature sensor is located at the oil inlet of the high-pressure evaporator.

[0011] Furthermore, it also includes a first constant flow valve, a second constant flow valve, a first temperature-controlled three-way valve, and a second temperature-controlled three-way valve. The outlet of the cylinder liner water heater is connected to one end of the first constant flow valve and one end of the second constant flow valve. The other end of the first constant flow valve is connected to the inlet of the first temperature-controlled three-way valve. The first outlet of the first temperature-controlled three-way valve is connected to one end of the water maker. The other end of the second constant flow valve is connected to the inlet of the second temperature-controlled three-way valve. The first outlet of the second temperature-controlled three-way valve is connected to the inlet of the low-pressure evaporator. The second outlet of the first temperature-controlled three-way valve is connected to the second outlet of the second temperature-controlled three-way valve, the other end of the water maker, the outlet of the low-pressure evaporator, and the inlet of the degassing chamber.

[0012] Furthermore, the energy storage system adopts a supercapacitor-lithium battery hybrid energy storage system.

[0013] Furthermore, the organic working fluid used in the low-pressure evaporator and the high-pressure evaporator is a low-boiling-point non-CFC working fluid.

[0014] Furthermore, the high-voltage generator and the low-voltage generator are permanent magnet generators.

[0015] A control method for a marine main engine cylinder liner water and exhaust gas waste heat recovery power generation system includes the following steps: Operating Condition 1: When the ship's main engine starts from standby or when the cylinder liner water temperature is lower than the preset minimum value, manually open the manual valve on the steam side of the cylinder liner water heater to start the cylinder liner water heater. Close the manual valve when the cylinder liner water is heated to the first preset temperature.

[0016] Operating Condition 2: When the cylinder liner water temperature reaches the second preset value, the opening direction of the first and second temperature-controlled three-way valves is adjusted to the water maker / low-pressure evaporator side, allowing the cylinder liner water to enter the low-pressure evaporator and water maker pipelines. The water maker starts working and produces fresh water. At the same time, the low-pressure working fluid pump and the central cooling fresh water pump receive the temperature sensor signal and start running, driving the organic working fluid and central cooling fresh water to circulate. The organic working fluid evaporates in the low-pressure evaporator and enters the low-pressure turbine, driving the low-pressure turbine to rotate. This, in turn, drives the low-pressure generator rotor to cut magnetic field lines, and the organic Rankine cycle power generation system starts generating electricity, which is then delivered to the supercapacitor-lithium battery hybrid energy storage system. When the electrical equipment needs electricity, the supercapacitor outputs electricity smoothly and stably. When the electrical equipment stops needing electricity, the lithium battery stores the energy of the organic Rankine cycle.

[0017] Operating Condition 3: Based on the signals from the first, second, and third temperature sensors, the low-pressure and high-pressure working fluid pumps are started and stopped, further controlling the output of the organic Rankine cycle. When the cylinder liner water temperature drops to the third preset value, the opening direction of the second temperature-controlled three-way valve is adjusted, preventing cylinder liner water from entering the low-pressure evaporator. The low-pressure working fluid pump and the central cooling freshwater pump stop operating, and the low-pressure turbine stops outputting power. The opening direction of the first temperature-controlled three-way valve is also adjusted at this time to prioritize ensuring the temperature at the inlet of the water maker so that it can operate normally. At this time, the second temperature sensor transmits a signal to the central cooling freshwater system and the temperature control valve, adjusting the opening of the temperature control valve to stop the central cooling freshwater from entering the cylinder liner cooling water system, causing the cylinder liner water temperature to rise again.

[0018] Operating Condition 4: When the cylinder liner water temperature rises to the fourth preset value, both the first and second thermostatic three-way valves open, allowing all the cylinder liner water to enter the water maker and low-pressure evaporator. The water maker and organic Rankine cycle power generation system operate normally. When the cylinder liner water temperature rises to the fifth preset value, the heat consumed by the water maker and low-pressure evaporator is insufficient to maintain the cylinder liner water temperature. The second temperature sensor transmits a signal to the central cooling freshwater system and the thermostatic valve, adjusting the opening of the thermostatic valve to allow central cooling freshwater to enter the cylinder liner water system, thereby lowering the cylinder liner water temperature.

[0019] Operating Condition 5: When there is a surplus of steam generated by the waste gas combined boiler, the steam pressure inside the waste gas combined boiler increases. The pressure sensor inside the waste gas combined boiler transmits a signal to the pressure-controlled three-way valve, and the outlet of the pressure-controlled three-way valve opens to the thermal oil heater side. The surplus steam enters the thermal oil heater, and at the same time, the pressure sensor transmits a signal to control the operation of the thermal oil circulation pump. When the temperature reaches the sixth preset value, the third temperature sensor transmits a signal to the high-pressure working fluid pump and the central cooling fresh water pump to start them. The organic working fluid is heated in the high-pressure evaporator by the thermal oil to obtain steam at a higher pressure, thereby enabling the organic Rankine cycle to obtain better output efficiency. When there is a surplus of steam generated by the waste gas combined boiler but the cylinder liner water temperature is insufficient, the pressure sensor inside the waste gas boiler controls the operation of the high-pressure working fluid pump and the central cooling fresh water pump. The working fluid pump operates at the speed corresponding to this operating condition.

[0020] Operating Condition 6: When the surplus steam generated by the waste gas combined boiler is insufficient, the steam pressure inside the waste gas combined boiler decreases. The pressure sensor of the waste gas combined boiler transmits a signal to the pressure-controlled three-way valve, closing the pressure-controlled three-way valve to stop steam from entering the thermal oil heater side. When the amount of steam generated on the waste gas side of the waste gas combined boiler is insufficient to meet the steam demand and more steam is obtained by burning fuel, the pressure-controlled three-way valve on the thermal oil heater side is normally closed and the thermal oil pump stops working.

[0021] Compared with existing technologies, this invention has the following advantages and effects: This invention provides a waste heat recovery and power generation system and control method for ship main engine cylinder liner water and exhaust gas. It can not only effectively recover waste heat from the ship's main engine cylinder liner water, but also recover excess waste heat through steam in an exhaust gas boiler. Furthermore, it utilizes evaporators at different pressures for cascaded utilization of waste heat, efficiently converting the internal energy of waste heat into electrical energy using the organic Rankine cycle. This invention employs a parallel structure in the cylinder liner water system and a partial pressure evaporation structure in the organic Rankine cycle system to more effectively and efficiently recover waste heat and convert it into electrical energy. This invention receives and outputs electrical energy generated by the organic Rankine cycle power generation system through a supercapacitor-lithium battery hybrid energy storage system, effectively mitigating power fluctuations. This invention can improve the overall greenness of ships, reduce fuel consumption, and increase economic efficiency. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a marine main engine cylinder liner water and waste gas waste heat recovery power generation system according to the present invention.

[0023] Figure 2 This is a logic diagram of a control method for a marine main engine cylinder liner water and waste heat recovery power generation system according to the present invention.

[0024] Figure 3 This is a schematic diagram of the supercapacitor-lithium battery hybrid energy storage system of the present invention. Detailed Implementation

[0025] To illustrate in detail the technical solutions adopted by the present invention to achieve the intended technical objectives, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Furthermore, the technical means or technical features in the embodiments of the present invention can be replaced without creative effort. The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0026] like Figure 1 As shown, the present invention discloses a marine main engine cylinder liner water and exhaust gas waste heat recovery power generation system, comprising a marine main engine 1, an exhaust gas combined boiler 2, an energy storage system 3, a cylinder liner water heater 4, a water maker 5, a degassing chamber 6, an expansion tank 7, a cylinder liner cooling water pump 8, a temperature control valve 24, an organic Rankine cycle system, and an exhaust gas booster 16. The cylinder liner water outlet of the marine main engine 1 is connected to the inlet of the cylinder liner water heater 4, the outlet of the cylinder liner water heater 4 is connected to one end of the water maker 5, the other end of the water maker 5 is connected to the inlet of the degassing chamber 6, and the outlet of the degassing chamber 6 is connected to the inlet of the expansion tank 7. The first outlet of the expansion tank 7 is connected to the inlet of the central cooling fresh water system. The outlet of the central cooling fresh water system is connected to the inlet of the temperature control valve 24. The outlet of the degassing chamber 6 is connected to the second outlet of the expansion tank 7, the outlet of the temperature control valve 24, and one end of the cylinder liner cooling water pump 8. The other end of the cylinder liner cooling water pump 8 is connected to the cylinder liner water inlet of the main engine 1. The exhaust gas outlet of the main engine 1 is connected to the inlet of the exhaust gas booster 16. The exhaust gas booster 16 outlet is connected to the inlet of the exhaust gas combined boiler 2. The steam loop of the exhaust gas combined boiler 2 is connected to the organic Rankine cycle system.

[0027] The main engine 1 is a mechanical device on a ship that converts the chemical energy in fuel into mechanical energy to generate propulsion power. Fuel types include, but are not limited to, fuel oil, natural gas, methanol, and other substances that can be broadly defined as fuel. The cylinder liner water heater 4 is located at the cylinder liner water outlet of the main engine 1 and uses steam to heat the cylinder liner water only when the cylinder liner water temperature is too low or when the main engine is started.

[0028] The degassing chamber 6 is typically a sealed container with an exhaust valve at the top, connected to a high-level expansion tank 7, used to discharge gases from the cylinder liner cooling water circulation system. The expansion tank 7 receives the gases discharged from the degassing chamber 6 and compensates for changes in the cylinder liner cooling water volume. The central cooling freshwater system is connected to the cylinder liner cooling water system via a temperature-controlled three-way valve to regulate the cylinder liner water temperature.

[0029] The organic Rankine cycle system includes a low-pressure evaporator 9, a high-pressure evaporator 10, a low-pressure turbine 1101, a low-pressure generator 1201, a high-pressure turbine 1102, a high-pressure generator 1202, a condenser 13, a low-pressure working fluid pump 14, a high-pressure working fluid pump 15, a thermal oil heater 17, a thermal oil pump 18, and a central cooling freshwater pump 19. The outlet of the central cooling freshwater system is connected to the inlet of the central cooling freshwater pump 19. The inlet of the condenser 13 is connected to the outlet of the central cooling freshwater pump 19. The outlet of the condenser 13 is connected to the inlet of the central cooling freshwater system. The air inlet of the condenser 13 is connected to the outlets of the low-pressure turbine 1101 and the high-pressure turbine 1102. The outlet of the condenser 13 is connected to one end of the low-pressure working fluid pump 14 and one end of the high-pressure working fluid pump 15. The other end of the low-pressure working fluid pump 14 is connected to the working fluid inlet of the low-pressure evaporator 9. The working fluid outlet of the low-pressure evaporator 9 is connected to the air inlet of the low-pressure turbine 1101. The low-pressure turbine 1101 is connected to the low-pressure generator 1201. The other end of the high-pressure working fluid pump 15 is connected to the working fluid inlet of the high-pressure evaporator 10. The working fluid outlet of the high-pressure evaporator 10 is connected to the air inlet of the high-pressure turbine 1102. The high-pressure turbine 1102 is connected to the high-pressure generator 1202. The high-pressure generator 1202 and the low-pressure generator 1201 are connected to the energy storage system 3. The heat transfer oil outlet of the high-pressure evaporator 10 is connected to one end of the heat transfer oil pump 18. The other end of the heat transfer oil pump 18 is connected to the heat transfer oil inlet of the heat transfer oil heater 17. The heat transfer oil outlet of the heat transfer oil heater 17 is connected to the heat transfer oil inlet of the high-pressure evaporator 10.

[0030] The exhaust gas combined boiler 2 is a device that uses the exhaust gas from fuel combustion in the ship's main engine to heat fresh water and obtain high-temperature, high-pressure steam. When the steam generated on the exhaust gas side of the exhaust gas combined boiler 2 is insufficient, it can obtain high-temperature, high-pressure steam by burning additional fuel to heat the fresh water. It is only used when the high-temperature, high-pressure steam generated by the exhaust gas boiler does not meet the usage requirements.

[0031] The central cooling freshwater pump 19 is installed before the condensate inlet of the condenser in the central cooling freshwater system entering the organic Rankine cycle system, and is used to drive the cooling water circulation.

[0032] The organic Rankine cycle system also includes a pressure-controlled three-way valve 25 and a pressure sensor 27. The pressure sensor 27 is installed on the waste gas combined boiler 2. The steam outlet of the waste gas combined boiler 2 is connected to the inlet of the pressure-controlled three-way valve 25. The first outlet of the pressure-controlled three-way valve 25 is connected to the steam inlet of the waste gas combined boiler 2 and the steam outlet of the thermal oil heater 17. The second outlet of the pressure-controlled three-way valve 25 is connected to the steam inlet of the thermal oil heater 17.

[0033] The waste heat recovery power generation system for marine main engine cylinder liner water and exhaust gas of the present invention also includes a manual valve 26. One end of the manual valve 26 is connected to an external steam supply end, and the other end of the manual valve 26 is connected to the air inlet of the cylinder liner water heater 4. The air outlet of the cylinder liner water heater 4 is connected to an external steam return end.

[0034] The waste heat recovery power generation system for ship main engine cylinder liner water and exhaust gas of the present invention further includes a first temperature sensor 28, a second temperature sensor 29 and a third temperature sensor 30. The first temperature sensor 28 and the second temperature sensor 29 are installed at the water outlet of the ship main engine 1 cylinder liner, and the third temperature sensor 30 is installed at the heat transfer oil inlet of the high-pressure evaporator 10.

[0035] The marine main engine cylinder liner water and waste heat recovery power generation system of the present invention further includes a first constant flow valve 21, a second constant flow valve 20, a first temperature-controlled three-way valve 22, and a second temperature-controlled three-way valve 23. The outlet of the cylinder liner water heater 4 is connected to one end of the first constant flow valve 21 and one end of the second constant flow valve 20. The other end of the first constant flow valve 21 is connected to the inlet of the first temperature-controlled three-way valve 22. The first outlet of the first temperature-controlled three-way valve 22 is connected to one end of the water maker 5. The other end of the second constant flow valve 20 is connected to the inlet of the second temperature-controlled three-way valve 23. The first outlet of the second temperature-controlled three-way valve 23 is connected to the inlet of the low-pressure evaporator 9. The second outlet of the first temperature-controlled three-way valve 22 is connected to the second outlet of the second temperature-controlled three-way valve 23, the other end of the water maker 5, the outlet of the low-pressure evaporator 9, and the inlet of the degassing chamber 6.

[0036] like Figure 3 As shown, energy storage system 3 employs a supercapacitor-lithium battery hybrid energy storage system. It stores the electricity generated by the organic Rankine cycle generator and outputs power to electrical equipment, mitigating power fluctuations in the organic Rankine cycle power generation system caused by potential heat source fluctuations. A supercapacitor-lithium battery parallel active topology is used, where the supercapacitor handles the fluctuations generated by the organic Rankine cycle power generation system when electrical equipment is in use, while the lithium battery stores excess energy when the equipment is not in use.

[0037] The low-pressure evaporator 9 and the high-pressure evaporator 10 use low-boiling-point non-CFC working fluids. The low-pressure evaporator 9 and the high-pressure evaporator 10 heat the organic working fluids with cylinder liner water or high-temperature heat transfer oil, respectively, so that they evaporate to reach saturated high-pressure gas.

[0038] The high-voltage generator 1202 and the low-voltage generator 1201 are permanent magnet generators. They generate electricity by rotating a turbine to drive a rotor to cut magnetic field lines. A speed governor is provided to control the output frequency, and the generated electricity is sent to a supercapacitor lithium battery energy storage system for storage.

[0039] like Figure 2As shown, a control method for a marine main engine cylinder liner water and exhaust gas waste heat recovery power generation system includes the following steps: Operating Condition 1: When the ship's main engine starts from standby or when the cylinder liner water temperature is lower than the preset minimum value, manually open the manual valve on the steam side of the cylinder liner water heater to start the cylinder liner water heater. Close the manual valve when the cylinder liner water is heated to the first preset temperature.

[0040] Operating Condition 2: When the cylinder liner water temperature reaches the second preset value, the opening direction of the first and second temperature-controlled three-way valves is adjusted to the water maker / low-pressure evaporator side, allowing the cylinder liner water to enter the low-pressure evaporator and water maker pipelines. The water maker starts working and produces fresh water. At the same time, the low-pressure working fluid pump and the central cooling fresh water pump receive the temperature sensor signal and start running, driving the organic working fluid and central cooling fresh water to circulate. The organic working fluid evaporates in the low-pressure evaporator and enters the low-pressure turbine, driving the low-pressure turbine to rotate. This, in turn, drives the low-pressure generator rotor to cut magnetic field lines, and the organic Rankine cycle power generation system starts generating electricity, which is then delivered to the supercapacitor-lithium battery hybrid energy storage system. When the electrical equipment needs electricity, the supercapacitor outputs electricity smoothly and stably. When the electrical equipment stops needing electricity, the lithium battery stores the energy of the organic Rankine cycle.

[0041] Operating Condition 3: Based on the signals from the first, second, and third temperature sensors, the low-pressure and high-pressure working fluid pumps are started and stopped, further controlling the output of the organic Rankine cycle. When the cylinder liner water temperature drops to the third preset value, the opening direction of the second temperature-controlled three-way valve is adjusted, preventing cylinder liner water from entering the low-pressure evaporator. The low-pressure working fluid pump and the central cooling freshwater pump stop operating, and the low-pressure turbine stops outputting power. The opening direction of the first temperature-controlled three-way valve is also adjusted at this time to prioritize ensuring the temperature at the inlet of the water maker so that it can operate normally. At this time, the second temperature sensor transmits a signal to the central cooling freshwater system and the temperature control valve, adjusting the opening of the temperature control valve to stop the central cooling freshwater from entering the cylinder liner cooling water system, causing the cylinder liner water temperature to rise again.

[0042] Operating Condition 4: When the cylinder liner water temperature rises to the fourth preset value, both the first and second thermostatic three-way valves open, allowing all the cylinder liner water to enter the water maker and low-pressure evaporator. The water maker and organic Rankine cycle power generation system operate normally. When the cylinder liner water temperature rises to the fifth preset value, the heat consumed by the water maker and low-pressure evaporator is insufficient to maintain the cylinder liner water temperature. The second temperature sensor transmits a signal to the central cooling freshwater system and the thermostatic valve, adjusting the opening of the thermostatic valve to allow central cooling freshwater to enter the cylinder liner water system, thereby lowering the cylinder liner water temperature.

[0043] Operating Condition 5: When there is a surplus of steam generated by the waste gas combined boiler, the steam pressure inside the waste gas combined boiler increases. The pressure sensor inside the waste gas combined boiler transmits a signal to the pressure-controlled three-way valve, and the outlet of the pressure-controlled three-way valve opens to the thermal oil heater side. The surplus steam enters the thermal oil heater, and at the same time, the pressure sensor transmits a signal to control the operation of the thermal oil circulation pump. When the temperature reaches the sixth preset value, the third temperature sensor transmits a signal to the high-pressure working fluid pump and the central cooling fresh water pump to start them. The organic working fluid is heated in the high-pressure evaporator by the thermal oil to obtain steam at a higher pressure, thereby enabling the organic Rankine cycle to obtain better output efficiency. When there is a surplus of steam generated by the waste gas combined boiler but the cylinder liner water temperature is insufficient, the pressure sensor inside the waste gas boiler controls the operation of the high-pressure working fluid pump and the central cooling fresh water pump. The working fluid pump operates at the speed corresponding to this operating condition.

[0044] Operating Condition 6: When the surplus steam generated by the waste gas combined boiler is insufficient, the steam pressure inside the waste gas combined boiler decreases. The pressure sensor of the waste gas combined boiler transmits a signal to the pressure-controlled three-way valve, closing the pressure-controlled three-way valve to stop steam from entering the thermal oil heater side. When the amount of steam generated on the waste gas side of the waste gas combined boiler is insufficient to meet the steam demand and more steam is obtained by burning fuel, the pressure-controlled three-way valve on the thermal oil heater side is normally closed and the thermal oil pump stops working.

[0045] This invention provides a waste heat recovery and power generation system and control method for ship main engine cylinder liner water and exhaust gas. It not only effectively recovers waste heat from the main engine cylinder liner water, but also recovers excess waste heat via steam from an exhaust gas boiler. Furthermore, it utilizes evaporators at different pressures for cascaded utilization of the waste heat, efficiently converting the internal energy of the waste heat into electrical energy using the organic Rankine cycle. The invention employs a parallel structure in the cylinder liner water system and a partial pressure evaporation structure in the organic Rankine cycle system to more effectively and efficiently recover waste heat and convert it into electrical energy. The invention uses a supercapacitor-lithium battery hybrid energy storage system to receive and output the electrical energy generated by the organic Rankine cycle power generation system, effectively mitigating power fluctuations. This invention improves the overall greenness of ships, reduces fuel consumption, and enhances economic efficiency.

[0046] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent substitutions, and improvements made to the above embodiments without departing from the scope of the present invention, based on the technical essence of the present invention and within the spirit and principles of the present invention, shall still fall within the protection scope of the present invention.

Claims

1. A waste heat recovery and power generation system for marine main engine cylinder liner water and exhaust gas, characterized in that: The system includes a marine main engine, a combined exhaust gas boiler, an energy storage system, a cylinder liner water heater, a water maker, a degassing chamber, an expansion tank, a cylinder liner cooling water pump, a temperature control valve, an organic Rankine cycle system, and an exhaust gas booster. The cylinder liner water outlet of the main engine is connected to the cylinder liner water heater inlet. The cylinder liner water heater outlet is connected to one end of the water maker, and the other end of the water maker is connected to the degassing chamber inlet. The degassing chamber outlet is connected to the expansion tank inlet. The first outlet of the expansion tank is connected to the central cooling freshwater system. The system's inlet is connected to the outlet of the central cooling freshwater system, which is connected to the inlet of the temperature control valve. The outlet of the degassing chamber is connected to the second outlet of the expansion tank, the outlet of the temperature control valve, and one end of the cylinder liner cooling water pump. The other end of the cylinder liner cooling water pump is connected to the cylinder liner water inlet of the main engine. The exhaust outlet of the main engine is connected to the inlet of the exhaust gas booster. The outlet of the exhaust gas booster is connected to the inlet of the exhaust gas combined boiler. The steam loop of the exhaust gas combined boiler is connected to the organic Rankine cycle system.

2. The waste heat recovery and power generation system for marine main engine cylinder liner water and exhaust gas according to claim 1, characterized in that: The organic Rankine cycle system includes a low-pressure evaporator, a high-pressure evaporator, a low-pressure turbine, a low-pressure generator, a high-pressure turbine, a high-pressure generator, a condenser, a low-pressure working fluid pump, a high-pressure working fluid pump, a thermal oil heater, a thermal oil pump, and a central cooling freshwater pump. The outlet of the central cooling freshwater system is connected to the inlet of the central cooling freshwater pump. The inlet of the condenser is connected to the outlet of the central cooling freshwater pump. The outlet of the condenser is connected to the inlet of the central cooling freshwater system. The air inlet of the condenser is connected to the air outlets of both the low-pressure and high-pressure turbines. The outlet of the condenser is connected to one end of the low-pressure working fluid pump and one end of the high-pressure working fluid pump. The other end of the low-pressure working fluid pump is connected to the working fluid inlet of the low-pressure evaporator. The working fluid outlet of the low-pressure evaporator is connected to the air inlet of the low-pressure turbine. The low-pressure turbine is connected to the low-pressure generator. The other end of the high-pressure working fluid pump is connected to the working fluid inlet of the high-pressure evaporator. The working fluid outlet of the high-pressure evaporator is connected to the air inlet of the high-pressure turbine. The high-pressure turbine is connected to the high-pressure generator. The high-pressure generator and the low-pressure generator are connected to the energy storage system. The heat transfer oil outlet of the high-pressure evaporator is connected to one end of the heat transfer oil pump. The other end of the heat transfer oil pump is connected to the heat transfer oil inlet of the heat transfer oil heater. The heat transfer oil outlet of the heat transfer oil heater is connected to the heat transfer oil inlet of the high-pressure evaporator.

3. The waste heat recovery and power generation system for marine main engine cylinder liner water and exhaust gas according to claim 1, characterized in that: The organic Rankine cycle system also includes a pressure-controlled three-way valve and a pressure sensor. The pressure sensor is installed on the waste gas combined boiler. The steam outlet of the waste gas combined boiler is connected to the inlet of the pressure-controlled three-way valve. The first outlet of the pressure-controlled three-way valve is connected to the steam inlet of the waste gas combined boiler and the steam outlet of the thermal oil heater. The second outlet of the pressure-controlled three-way valve is connected to the steam inlet of the thermal oil heater.

4. The waste heat recovery and power generation system for marine main engine cylinder liner water and exhaust gas according to claim 1, characterized in that: It also includes a manual valve, one end of which is connected to the external steam supply end, and the other end of which is connected to the air inlet of the cylinder liner water heater. The air outlet of the cylinder liner water heater is connected to the external steam return end.

5. A waste heat recovery and power generation system for marine main engine cylinder liner water and exhaust gas according to claim 1, characterized in that: It also includes a first temperature sensor, a second temperature sensor and a third temperature sensor. The first and second temperature sensors are located at the water outlet of the ship's main engine cylinder liner, and the third temperature sensor is located at the oil inlet of the high-pressure evaporator.

6. A waste heat recovery and power generation system for marine main engine cylinder liner water and exhaust gas according to claim 5, characterized in that: It also includes a first constant flow valve, a second constant flow valve, a first temperature-controlled three-way valve, and a second temperature-controlled three-way valve. The outlet of the cylinder liner water heater is connected to one end of the first constant flow valve and one end of the second constant flow valve. The other end of the first constant flow valve is connected to the inlet of the first temperature-controlled three-way valve. The first outlet of the first temperature-controlled three-way valve is connected to one end of the water maker. The other end of the second constant flow valve is connected to the inlet of the second temperature-controlled three-way valve. The first outlet of the second temperature-controlled three-way valve is connected to the inlet of the low-pressure evaporator. The second outlet of the first temperature-controlled three-way valve is connected to the second outlet of the second temperature-controlled three-way valve, the other end of the water maker, the outlet of the low-pressure evaporator, and the inlet of the degassing chamber.

7. A waste heat recovery and power generation system for marine main engine cylinder liner water and exhaust gas according to claim 1, characterized in that: The energy storage system adopts a hybrid energy storage system of supercapacitor and lithium battery.

8. A waste heat recovery and power generation system for marine main engine cylinder liner water and exhaust gas according to claim 2, characterized in that: The organic working fluid used in the low-pressure evaporator and the high-pressure evaporator is a low-boiling-point non-CFC working fluid.

9. A waste heat recovery and power generation system for marine main engine cylinder liner water and exhaust gas according to claim 2, characterized in that: The high-voltage generator and the low-voltage generator are permanent magnet generators.

10. A control method for a marine main engine cylinder liner water and waste gas waste heat recovery power generation system according to any one of claims 1-9, characterized in that... Includes the following steps: Operating Condition 1: When the ship's main engine starts from standby or when the cylinder liner water temperature is lower than the preset minimum value, manually open the manual valve on the steam side of the cylinder liner water heater to start the cylinder liner water heater. Close the manual valve when the cylinder liner water is heated to the first preset temperature. Operating Condition 2: When the cylinder liner water temperature reaches the second preset value, the opening direction of the first and second temperature-controlled three-way valves is adjusted to the water maker / low-pressure evaporator side, allowing the cylinder liner water to enter the low-pressure evaporator and water maker pipelines. The water maker starts working and produces fresh water. At the same time, the low-pressure working fluid pump and the central cooling fresh water pump receive the temperature sensor signal and start running, driving the organic working fluid and central cooling fresh water to circulate. The organic working fluid evaporates in the low-pressure evaporator and enters the low-pressure turbine, driving the low-pressure turbine to rotate. This, in turn, drives the low-pressure generator rotor to cut magnetic field lines, and the organic Rankine cycle power generation system starts generating electricity, which is then delivered to the supercapacitor-lithium battery hybrid energy storage system. When the electrical equipment needs electricity, the supercapacitor outputs electricity smoothly and stably. When the electrical equipment stops needing electricity, the lithium battery stores the energy of the organic Rankine cycle. Operating Condition 3: Based on the signals from the first, second, and third temperature sensors, the low-pressure and high-pressure working fluid pumps are started and stopped, further controlling the output of the organic Rankine cycle. When the cylinder liner water temperature drops to the third preset value, the opening direction of the second temperature-controlled three-way valve is adjusted, preventing cylinder liner water from entering the low-pressure evaporator. The low-pressure working fluid pump and the central cooling freshwater pump stop operating, and the low-pressure turbine stops outputting power. The opening direction of the first temperature-controlled three-way valve is also adjusted at this time to prioritize ensuring the temperature at the inlet of the water maker so that it can operate normally. At this time, the second temperature sensor transmits a signal to the central cooling freshwater system and the temperature control valve, adjusting the opening of the temperature control valve to stop the central cooling freshwater from entering the cylinder liner cooling water system, causing the cylinder liner water temperature to rise again. Operating Condition 4: When the cylinder liner water temperature rises to the fourth preset value, both the first and second thermostatic three-way valves open, allowing all the cylinder liner water to enter the water maker and low-pressure evaporator. The water maker and organic Rankine cycle power generation system operate normally. When the cylinder liner water temperature rises to the fifth preset value, the heat consumed by the water maker and low-pressure evaporator is insufficient to maintain the cylinder liner water temperature. The second temperature sensor transmits a signal to the central cooling freshwater system and the thermostatic valve, adjusting the opening of the thermostatic valve to allow central cooling freshwater to enter the cylinder liner water system, thereby lowering the cylinder liner water temperature. Operating Condition 5: When there is a surplus of steam generated by the waste gas combined boiler, the steam pressure inside the waste gas combined boiler increases. The pressure sensor inside the waste gas combined boiler transmits a signal to the pressure-controlled three-way valve, and the outlet of the pressure-controlled three-way valve opens to the thermal oil heater side. The surplus steam enters the thermal oil heater, and at the same time, the pressure sensor transmits a signal to control the operation of the thermal oil circulation pump. When the temperature reaches the sixth preset value, the third temperature sensor transmits a signal to the high-pressure working fluid pump and the central cooling fresh water pump to start them. The organic working fluid is heated in the high-pressure evaporator by the thermal oil to obtain steam at a higher pressure, thereby enabling the organic Rankine cycle to obtain better output efficiency. When there is a surplus of steam generated by the waste gas combined boiler but the cylinder liner water temperature is insufficient, the pressure sensor inside the waste gas boiler controls the operation of the high-pressure working fluid pump and the central cooling fresh water pump. The working fluid pump operates at the speed corresponding to this operating condition. Operating Condition 6: When the surplus steam generated by the waste gas combined boiler is insufficient, the steam pressure inside the waste gas combined boiler decreases. The pressure sensor of the waste gas combined boiler transmits a signal to the pressure-controlled three-way valve, closing the pressure-controlled three-way valve to stop steam from entering the thermal oil heater side. When the amount of steam generated on the waste gas side of the waste gas combined boiler is insufficient to meet the steam demand and more steam is obtained by burning fuel, the pressure-controlled three-way valve on the thermal oil heater side is normally closed and the thermal oil pump stops working.

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