An energy-saving system for LNG fuel ship coupling LNG cold energy power generation and ORC power generation

Abstract

The application discloses an energy-saving system suitable for coupling LNG cold energy power generation and ORC power generation, and belongs to the fields of ship engineering and energy saving. The LNG cold energy power generation system comprises an LNG storage tank (1), an LNG pump (11), an LNG evaporator (10), an LNG turbine generator (9), an NG reheater (7), a gas supply buffer tank (12) and the like. The application utilizes both LNG cold energy power generation and flue gas waste heat organic Rankine cycle (ORC) power generation, and the two are combined with each other. The cold energy released by LNG gasification is used for organic medium condensation, and the heat of the ORC evaporator comes from flue gas waste heat or cylinder jacket water. After LNG power generation, the LNG is reheated to a proper temperature to supply gas to the main engine, and the cold energy in the reheating process is used for organic medium condensation. The organic medium condensation process is completed in two condensers. A gas-liquid separator is arranged between the two condensers to reduce two-phase flow in the system and inhibit the negative influence of the sloshing working condition on the system during ship sailing.

Description

TECHNICAL FIELD

[0001] The present application relates to an energy-saving system coupling LNG cold energy power generation and ORC power generation for LNG fuel ship, belonging to the field of ship engineering and energy saving. Specifically, LNG cold energy is used for power generation to supply gas to the main engine or auxiliary engine, and flue gas waste heat is used for ORC power generation, the cold energy released in the evaporation and reheating process of the former is exchanged with the heat released in the liquefaction process of the latter, and cold and heat are coupled. BACKGROUND

[0002] About 50% of the thermal energy generated by the fuel combustion of the ship engine in the working process is taken away by the exhaust gas and cylinder liner water and discharged into the environment, resulting in low fuel utilization rate. A large amount of waste heat is contained in the exhaust gas, which is not conducive to recovery due to low grade. If the waste heat of the ship is recovered, the energy utilization rate of the main engine can be improved, fuel consumption can be reduced, and waste discharge can be reduced, thereby playing a role in energy saving and emission reduction.

[0003] Organic Rankine Cycle (ORC) has been widely studied in many fields due to its high thermal efficiency, simple structure, high reliability, low cost, easy maintenance and other advantages, such as industrial waste heat recovery, internal combustion engine waste heat recovery, solar energy utilization, geothermal energy utilization, etc. ORC can convert low-grade heat energy into required electric energy or mechanical energy, thereby improving the energy use efficiency of the energy system. However, the condenser of the system needs a large amount of circulating water as medium for cooling.

[0004] The fuel gasification in the gas supply system of the LNG fuel ship usually uses ethylene glycol water solution to absorb the cold energy released in the gasification process, and then the ethylene glycol water solution needs to be heated by steam for temperature recovery. This process not only does not recover the cold energy, but also consumes steam heat, resulting in great energy waste. SUMMARY

[0005] The present application overcomes the above technical problems and defects, and provides an energy-saving system coupling LNG cold energy power generation and ORC power generation for LNG fuel ship.

[0006] The fuel supply system of the LNG fuel ship needs to gasify LNG during the voyage, which generates a large amount of cold energy. The conventional operation of this part of cold energy is absorbed by ethylene glycol water solution, and then the ethylene glycol water solution is heated by steam. This process consumes steam and has high energy consumption, and there is still room for improvement in the rational use of energy.

[0007] The application recycles the cold energy released in the fuel gasification process of the fuel supply system, and uses the excess heat from the cylinder liner water or flue gas on the ship as a heat source for ORC power generation.

[0008] Specifically, to achieve the above-mentioned purpose, the application provides the following technical scheme.

[0009] The energy-saving system for coupling LNG cold energy power generation and ORC power generation of the LNG fuel ship of the application is characterized in that it comprises an LNG cold energy power generation and supply system and a flue gas waste heat ORC power generation system.

[0010] The LNG cold energy power generation and supply system comprises an LNG storage tank (1), an LNG pump (11), an LNG evaporator (10), an LNG turbine generator (9), an LNG reheater (7) and a gas supply buffer tank (12); the LNG storage tank (1) is connected with the LNG pump (11), the LNG pump is connected with the LNG evaporator (10), the LNG evaporator is connected with the LNG turbine generator (9), the LNG turbine generator (9) is connected with the LNG reheater (7), and the LNG reheater is connected with the gas supply buffer tank (12).

[0011] The energy-saving system for ORC power generation comprises an ORC liquid storage tank (2), an ORC pump (3), an ORC preheater (4), an ORC evaporator (5) and an ORC turbine generator (6); the ORC liquid storage tank (2) is connected with the ORC pump (3), the ORC pump is connected with the ORC preheater (4), the ORC preheater (4) is connected with the ORC evaporator (5), and the ORC evaporator is connected with the ORC turbine generator (6); the ORC turbine generator (6) is connected with the LNG reheater (7), and the liquid phase pipeline of the LNG evaporator (10) leads to the ORC liquid storage tank (2).

[0012] The energy-saving system further comprises an ORC gas-liquid separator (8), the ORC gas-liquid separator (8) is connected with the LNG reheater (7), the gas phase pipeline of the ORC gas-liquid separator (8) is connected with the LNG evaporator (10), and the liquid phase pipeline of the ORC gas-liquid separator (8) leads to the ORC liquid storage tank (2).

[0013] The LNG turbine generator (9) and the ORC turbine generator (6) are both high-speed magnetic suspension generators.

[0014] The LNG evaporator (10) and the LNG reheater (7) are selected from one of a flat plate heat exchanger, a plate-fin heat exchanger, a coiled tube heat exchanger and a shell-and-tube heat exchanger.

[0015] Preferably, the LNG evaporator and the LNG reheater are selected from a plate-fin heat exchanger.

[0016] The ORC preheater (4) and the ORC evaporator (5) are selected from one of a flat plate heat exchanger, a plate-fin heat exchanger, a coiled tube heat exchanger, a printed circuit board heat exchanger and a shell-and-tube heat exchanger.

[0017] Preferably, the ORC preheater (4) and the ORC evaporator (5) are selected from a flat plate heat exchanger.

[0018] Further, the application also comprises a grid-connected cabinet (13), and the electricity output by the LNG turbine generator (9) and the ORC turbine generator (6) is connected to the main power grid of the ship through the grid-connected cabinet (13) to supply power to the electrical equipment.

[0019] The high-speed magnetic suspension generator structure of the application is: the rotor (9-5) adopts magnetic suspension bearing, the rotor (9-5) is directly connected with the impeller (9-4), the impeller is arranged in the volute (9-1), and the rotor is arranged in the generator shell (9-2); the volute and the generator shell (9-2) are connected through flanges; the organic medium enters the generator shell (9-2) after working through the impeller, passes through the motor shell to cool the motor; the outlet of the generator shell (9-2) is connected with the outlet pipe (9-3), the outlet pipe (9-3) adopts an eccentric variable-diameter pipe and is connected with the generator shell (9-2) and the pipeline through flanges.

[0020] The impeller (9-4) is any one of an axial flow type, a radial flow type or a radial-axial flow type; the impeller is matched with a rotating speed sensor.

[0021] The magnetic suspension bearing is provided with a protective bearing, a displacement sensor, a temperature detector and a UPS power supply.

[0022] The organic medium used by the ORC power generation system is one or more of 245fa or R123. The 245fa output by the ORC turbine generator (6) is used as a heat source to heat the LNG to make it gasify and to make it meet the temperature requirement of gas supply, and the 245fa is gradually condensed and liquefied in the above two heat exchangers. The heat exchange order of the 245fa with the LNG evaporator (10) and the NG reheater (7) can be changed, and preferably, the heat exchange order is that the NG reheater is heated first, and after gas-liquid separation, the gas phase enters the LNG evaporator for heat exchange. After two-stage condensation of the 245fa, the temperature is 40-50 DEG C.

[0023] The ORC gas-liquid separator (8) is used for separating the gas-liquid two-phase of 245fa after the first cooling, and is installed between the LNG re-heater (7) and the LNG evaporator (10), the gas phase of the ORC gas-liquid separator (8) is connected with the LNG evaporator (10), and the liquid phase of the ORC gas-liquid separator (8) and the liquid phase of the hot side of the LNG evaporator (10) are both connected with the ORC liquid storage tank (2). The installation position of the ORC gas-liquid separator (8) is higher than that of the ORC liquid storage tank (2), and a certain height difference is reserved.

[0024] The liquid inlet mode of the ORC liquid storage tank (2) can be that two liquid inlets are arranged on the storage tank, and two liquid paths enter the storage tank respectively. Alternatively, one liquid inlet is arranged on the storage tank, and two liquid paths enter the storage tank through a three-way joint after being collected on the inlet pipe of the storage tank. In this mode, a check valve needs to be arranged on the liquid phase pipeline out of the LNG evaporator.

[0025] The ORC pre-heater (4) uses jacket water as the heat source, and can also use the steam or the secondary heat exchange of the heat conducting oil out of the ORC evaporator (5) as the heat source, and can also use the steam of the organic medium to be condensed out of the ORC turbine generator (6) as the heat source. The temperature range of the available heat source is 80-120 DEG C.

[0026] The ORC evaporator (5) uses the steam or the high-temperature heat conducting oil produced by the flue gas waste heat as the heat source, and the temperature range of the heat source is 150-180 DEG C.

[0027] In the application, the natural gas after power generation by using the LNG cold energy enters a gas supply buffer tank to supply the gas to the main engine at a pressure and a temperature suitable for the demand of the main engine. The gas supply pressure range of the system is 16-300 bar, and the temperature range is 30-60 DEG C. The gas supply pressure of 16 bar can meet the gas demand of the four-stroke low-pressure gas main engine and the boiler. The gas supply pressure of 300 bar can meet the gas demand of the two-stroke low-speed main engine.

[0028] The application has the following beneficial effects:

[0029] Compared with the prior art, the heat source for LNG evaporation is changed from the ethylene glycol aqueous solution to the organic medium of the ORC system to be condensed, so that the steam for heating the ethylene glycol aqueous solution is saved, and the saved steam can be used for power generation of the ORC system. The original ORC power generation technology needs a large amount of circulating water for condensation, and after the coupling of the two power generation systems, the circulating water is not needed.

[0030] The condensation of the ORC is divided into two stages, and two different cold sources of the natural gas are utilized. The gas-liquid separator is arranged between the two-stage condensation to reduce the two-phase flow in the system and inhibit the influence of the ship sailing swing working condition on the system performance.

[0031] The system is designed in the form of a pry block, has small volume, few interfaces and is convenient to install.

[0032] The electricity generated by the two power generation systems can supplement the electricity demand on the ship, reduce the working load of the power generation auxiliary machine, and reduce the fuel consumption of the auxiliary machine. BRIEF DESCRIPTION OF DRAWINGS

[0033] Fig. 1 The structure diagram of the present application is shown.

[0034] Fig. 2 The structure diagram of the high-speed magnetic suspension generator of the present application is shown.

[0035] In the drawings:

[0036] LNG storage tank (1), ORC liquid storage tank (2), ORC pump (3), ORC preheater (4), ORC evaporator (5), ORC turbine generator (6), LNG reheater (7), ORC gas-liquid separator (8) LNG turbine generator (9), LNG evaporator (10), LNG pump (11), gas supply buffer tank (12);

[0037] Rotor (9-5), impeller (9-4), volute (9-1), generator shell (9-2), outlet pipe (9-3), Embodiment

[0038] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application. Embodiment

[0039] See Figs. 1-2 The embodiment provides an energy-saving system suitable for LNG fuel ship and coupling LNG cold energy power generation and ORC power generation, which integrates two systems of LNG cold energy power generation and flue gas waste heat ORC power generation. The LNG cold energy power generation system provides a cold source for the condenser of the ORC power generation system while meeting the demand of the main engine for gas supply after power generation. The heat source of the ORC power generation system comes from steam or high-temperature heat conducting oil produced by cylinder liner water and flue gas waste heat. The electricity generated by the two power generation systems is connected to the power grid of the ship and is used to supply power to the power-consuming equipment.

[0040] More specifically, the structure of the embodiment is as follows:

[0041] The LNG cold energy power generation gas supply system comprises: LNG storage tank 1, LNG pump 11, LNG evaporator 10, LNG turbine generator 9, LNG reheater 7, gas supply buffer tank 12 components; LNG storage tank 1 is connected with LNG pump 11, LNG pump is connected with LNG evaporator 10, LNG evaporator is connected with LNG turbine generator 9, LNG turbine generator 9 is connected with LNG reheater 7, and LNG reheater is connected with gas supply buffer tank 12.

[0042] The ORC power generation energy-saving system comprises: ORC liquid storage tank 2, ORC pump 3, ORC preheater 4, ORC evaporator 5, ORC turbine generator 6, ORC gas-liquid separator 8 components; ORC liquid storage tank 2 is connected with ORC pump 3, ORC pump is connected with ORC preheater 4, ORC preheater 4 is connected with ORC evaporator 5, and ORC evaporator is connected with ORC turbine generator 6;

[0043] ORC turbine generator 6 is connected with LNG reheater 7, LNG reheater 7 is connected with ORC gas-liquid separator 8, the gas phase pipeline of ORC gas-liquid separator 8 is connected with LNG evaporator 10, and the liquid phase pipeline of ORC gas-liquid separator 8 and the liquid phase pipeline of LNG evaporator 10 both lead to ORC liquid storage tank 2.

[0044] The LNG turbine generator 9 and the ORC turbine generator 6 both adopt high-speed magnetic suspension generators.

[0045] The LNG evaporator 10 and the LNG reheater 7 select one of a flat plate heat exchanger, a plate-fin heat exchanger, a coiled tube heat exchanger or a tube-shell heat exchanger.

[0046] The ORC preheater 4 and the ORC evaporator 5 select one of a flat plate heat exchanger, a plate-fin heat exchanger, a coiled tube heat exchanger or a tube-shell heat exchanger.

[0047] The embodiment also comprises a grid-connected cabinet 13, and the electricity output by the LNG turbine generator 9 and the ORC turbine generator 6 is connected with the ship main power grid through the grid-connected cabinet 13 to supply power to the electric equipment.

[0048] The high-speed magnetic suspension generator structure is that the rotor 9-5 adopts magnetic suspension bearings, the rotor 9-5 is directly connected with the impeller 9-4, the impeller is arranged in the volute 9-1, and the rotor is arranged in the generator shell 9-2; the volute is connected with the generator shell 9-2 through flanges; the organic medium enters the generator shell 9-2 after working through the impeller, passes through the motor shell to cool the motor; the outlet of the generator shell 9-2 is connected with the outlet pipe 9-3, and the outlet pipe 9-3 adopts an eccentric variable-diameter pipe and is connected with the generator shell 9-2 and the pipeline through flanges.

[0049] The impeller 9-4 is any one of an axial flow type, a radial flow type or a radial-axial flow type; the impeller is matched with a rotating speed sensor.

[0050] The magnetic suspension bearing is provided with a protection bearing, a displacement sensor, a temperature detector and a UPS power supply.

[0051] The ORC power generation system adopts one or more of 245fa or R123 as the organic medium. The 245fa from the ORC turbine generator 6 is used as a heat source to heat the LNG to be gasified and to heat the LNG to meet the gas supply temperature requirement, and the 245fa is gradually condensed and liquefied in the two heat exchangers. The heat exchange order of the 245fa and the LNG evaporator 10 and the NG reheater 7 can be changed, and the preferred heat exchange order is that the LNG reheater is heated first, and after gas-liquid separation, the gas phase enters the LNG evaporator for heat exchange. After two-stage condensation of the 245fa, the temperature is 40-50℃.

[0052] The gas-liquid two-phase 245fa after the first cooling is separated, and the installation position is between the LNG reheater 7 and the LNG evaporator 10. The gas phase of the ORC gas-liquid separator 8 is connected to the LNG evaporator 10, and the liquid phase of the ORC gas-liquid separator 8 and the liquid phase on the hot side of the LNG evaporator 10 are both connected to the ORC liquid storage tank 2. The installation position of the ORC gas-liquid separator 8 is higher than that of the ORC liquid storage tank 2, and a certain height difference is reserved.

[0053] The ORC liquid storage tank 2 can be provided with two liquid inlets, and two liquid paths enter the tank respectively. Alternatively, the tank can be provided with one liquid inlet, and the two liquid paths are collected through a three-way joint at the inlet pipe of the tank and then enter the tank together. In this case, a check valve needs to be installed on the liquid phase pipeline from the LNG evaporator.

[0054] The ORC preheater 4 uses cylinder jacket water as a heat source, or uses the steam from the ORC evaporator 5 or the secondary heat exchange of the heat conducting oil as a heat source, or uses the steam of the condensing organic medium from the ORC turbine generator 6 as a heat source. The temperature range of the available heat source is 80-120℃.

[0055] The ORC evaporator 5 uses steam generated by flue gas waste heat or high-temperature heat conducting oil as a heat source, and the temperature range of the heat source is 150-180℃.

[0056] The embodiment is a four-stroke main engine cold energy power generation low-pressure gas supply system coupled with an ORC power generation system, and the dual power generation system can realize power supply of 39kW, gas supply pressure of 16bar, gas supply temperature of 50℃ and gas supply amount of 385kg / h.

[0057] The LNG condensing power generation gas supply system process is: LNG from LNG storage tank 1 into LNG pump 11 pressurized to 30 bar, after pressurization LNG into LNG evaporator 10 for gasification, gasification temperature 40℃, high pressure natural gas into LNG turbine generator 9 expansion work, after power generation pressure is reduced to 16 bar, meet the main engine gas supply pressure demand, and power generation 17kW. After power generation into LNG reheater 7 is heated to 50℃, into the gas buffer tank 12, after pressure stabilization for main engine gas supply.

[0058] The ORC power generation system process is: organic medium from ORC liquid tank 2 into ORC pump 3 pressurized to 18 bar, into ORC preheater 4 and cylinder liner water heat exchange for preheating, preheating to 70-80℃. Then into ORC evaporator 5 and steam or heat transfer oil heat exchange gasification and superheating, after heat exchange temperature is 130-150℃. Gasification of high pressure high temperature organic medium steam into ORC turbine generator 6 expansion work, power generation 12kW. After expansion of the gas temperature drops to 110℃, the pressure is reduced to 4 bar. Into LNG reheater 7 to heat LNG turbine generator 9 out of low temperature natural gas, after heat exchange part of the organic medium liquefied, separated in ORC gas-liquid separator 8. After separation of the liquid phase organic medium to ORC liquid tank 2. Gas phase organic medium into LNG evaporator 10 continue to liquefy to supercooled state back to ORC liquid tank 2, two ways of liquid phase in the inlet and outlet liquid pipe before the pipeline through the three-way collection, ORC liquid tank 2 is provided with a liquid inlet, liquid tank 2 operating temperature 49℃. LNG evaporator 10 out of the liquid phase on the pipeline is equipped with check valve.

[0059] The steam or heat transfer oil heat source used in the ORC power generation system comes from the flue gas waste heat boiler.

[0060] Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacements to part of the technical features, any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. An energy-saving system for coupling LNG cold energy power generation and gas supply and ORC power generation suitable for LNG fueled ships, characterized by: The system comprises an LNG cold energy power generation and gas supply system and an ORC flue gas waste heat power generation system. The LNG cold energy power generation and gas supply system comprises an LNG storage tank (1), an LNG pump (11), an LNG evaporator (10), an LNG turbine generator (9), an LNG reheater (7) and a gas supply buffer tank (12); the LNG storage tank (1) is connected with the LNG pump (11), the LNG pump is connected with the LNG evaporator (10), the LNG evaporator is connected with the LNG turbine generator (9), the LNG turbine generator (9) is connected with the LNG reheater (7), and the LNG reheater is connected with the gas supply buffer tank (12). The ORC flue gas waste heat power generation system comprises an ORC liquid storage tank (2), an ORC pump (3), an ORC preheater (4), an ORC evaporator (5) and an ORC turbine generator (6); the ORC liquid storage tank (2) is connected with the ORC pump (3), the ORC pump is connected with the ORC preheater (4), the ORC preheater (4) is connected with the ORC evaporator (5), the ORC evaporator is connected with the ORC turbine generator (6); the ORC turbine generator (6) is connected with the LNG reheater (7), and a liquid phase pipeline of the LNG evaporator (10) leads to the ORC liquid storage tank (2). The system further comprises an ORC gas-liquid separator (8). The ORC gas-liquid separator (8) is connected with the LNG reheater (7), a gas phase pipeline of the ORC gas-liquid separator (8) is connected with the LNG evaporator (10), and a liquid phase pipeline of the ORC gas-liquid separator (8) leads to the ORC liquid storage tank (2).

2. The energy-saving system for coupling LNG cold energy power generation and gas supply and ORC power generation for LNG fueled ships according to claim 1 is characterized in that: The LNG turbine generator (9) and the ORC turbine generator (6) are both high-speed magnetic suspension generators.

3. The energy saving system suitable for LNG fuelled ships that couples the LNG cold energy power generation gas supply and the ORC power generation according to claim 1, characterized in that, The LNG evaporator (10) and the LNG reheater (7) are selected from one of a flat plate heat exchanger, a plate-fin heat exchanger, a coiled tube heat exchanger and a shell-and-tube heat exchanger.

4. The energy saving system suitable for LNG fuelled ships that couples the LNG cold energy power generation gas supply and the ORC power generation according to claim 1, characterized in that, The ORC preheater (4) and the ORC evaporator (5) are selected from one of a flat plate heat exchanger, a plate-fin heat exchanger, a coiled tube heat exchanger, a printed circuit board heat exchanger and a shell-and-tube heat exchanger.

5. The energy saving system suitable for LNG fuelled ships that couples the LNG cold energy power generation gas supply and the ORC power generation according to claim 1, characterized in that, The system further comprises a grid-connected cabinet (13), and the power output by the LNG turbine generator (9) and the ORC turbine generator (6) is connected with a ship main power grid through the grid-connected cabinet (13) to supply power to electrical equipment.

6. The energy saving system of claim 2, wherein, The high-speed magnetic suspension generator has the following structure: the rotor (9-5) adopts magnetic suspension bearings, the rotor (9-5) is directly connected with an impeller (9-4), the impeller is arranged in a volute (9-1), and the rotor is arranged in a generator shell (9-2); the volute is connected with the generator shell (9-2) through flanges; organic medium enters the generator shell (9-2) after working through the impeller, passes through the generator shell to cool the generator; an outlet pipe (9-3) is connected with the generator shell (9-2) outlet, and the outlet pipe (9-3) is an eccentric variable-diameter pipe and is connected with the generator shell (9-2) and a pipeline through flanges.

7. The energy saving system of claim 6, wherein, The impeller (9-4) is any one of an axial flow type, a radial flow type or a radial-axial flow type; the impeller is provided with a rotating speed sensor.

8. The energy saving system suitable for LNG fuelled ships that couples the LNG cold energy power generation gas supply and the ORC power generation according to claim 1, characterized in that, The gas supply pressure range of the system is 16-300 bar, and the temperature range is 30-60 DEG C; the gas supply pressure of 16 bar can meet the gas demand of four-stroke low-pressure gas main engine and boiler, and the gas supply pressure of 300 bar can meet the gas demand of two-stroke low-speed main engine.

9. The energy saving system suitable for LNG fuelled ships that couples the LNG cold energy power generation gas supply and the ORC power generation according to claim 1, characterized in that, The ORC preheater (4) uses cylinder jacket water as heat source, or uses the steam or secondary heat transfer of heat conducting oil from the ORC evaporator (5) as heat source, or uses the steam of organic medium to be condensed from the ORC turbine generator (6) as heat source, and the temperature range of the heat source is 80-120 DEG C.

10. The energy saving system suitable for LNG fuelled ships that couples the LNG cold energy power generation gas supply and the ORC power generation according to claim 1, characterized in that, The ORC evaporator (5) uses steam or high-temperature heat conducting oil produced by flue gas waste heat as heat source, and the temperature range of the heat source is 150-180 DEG C.

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