Zero-carbon high temperature reversible fuel cell power supply / storage system for lng receiving terminal

Abstract

The application discloses a zero-carbon high-temperature reversible fuel cell energy supply / storage system for an LNG receiving station. The energy supply / storage system has the following structure: a natural gas inlet of a natural gas reforming device is connected with an LNG storage tank, a product outlet is connected with an anode of a high-temperature reversible fuel cell power generation energy supply device, a cathode is connected with an oxygen / air inlet pipeline; a raw material inlet of a high-temperature reversible fuel cell electrolysis energy storage device is connected with a tail gas discharge pipeline of the high-temperature reversible fuel cell power generation energy supply device, a product gas outlet is connected with the anode of the high-temperature reversible fuel cell power generation energy supply device; the high-temperature reversible fuel cell electrolysis energy storage device is powered by offshore wind power; the high-temperature reversible fuel cell power generation energy supply device supplies power for the LNG receiving station; and heat of the system comes from waste heat generated by the high-temperature reversible fuel cell power generation energy supply device. The application makes full use of the heat energy by-produced by the high-temperature reversible fuel cell power generation energy supply device, realizes dynamic balance of heat demand of the system, and greatly improves energy utilization rate of the system.

Description

Technical Field

[0001] This invention relates to a zero-carbon emission high-temperature reversible fuel cell power supply / storage system for LNG receiving terminals, belonging to the field of high-temperature reversible fuel cell power supply and storage technology. Background Technology

[0002] Liquefied natural gas (LNG) is a clean and efficient fossil fuel. In my country, LNG is mainly transported from overseas via ocean trade. Dozens of LNG receiving terminals have been built along my country's coast. Their main function is to receive LNG, store it in large LNG storage tanks, and then use a gasification system to convert the LNG into gaseous natural gas, which is then exported via pressurized systems and pipelines to provide clean and efficient natural gas. Despite this, LNG receiving terminals have significant electricity demands. For example, an LNG receiving terminal with an annual processing capacity of 6 million tons consumes approximately 150 million kilowatt-hours of electricity annually, resulting in indirect carbon dioxide emissions of about 100,000 tons. Furthermore, the cryogenic nature of LNG inevitably leads to the formation of BOG (Boil Off Gas), with large LNG storage tanks typically evaporating 0.03% to 0.08% (by mass) of BOG daily. The amount of BOG generated by large LNG storage tanks is particularly substantial, requiring dedicated equipment to handle it and consuming significant additional electricity. Under the dual carbon context of "carbon peaking" and "carbon neutrality", how can we make LNG receiving terminals cleaner and lower carbon emissions to optimize their electricity demand and achieve energy conservation and emission reduction? Summary of the Invention

[0003] The purpose of this invention is to provide a clean and efficient zero-carbon emission novel high-temperature reversible energy supply and storage system for LNG receiving terminals. It uses liquefied natural gas as fuel and generates electricity using a high-temperature reversible solid oxide fuel cell to provide a stable power source for the LNG receiving terminal. At the same time, it utilizes offshore wind power to generate electricity by electrolyzing water and carbon dioxide in a high-temperature reversible solid oxide electrolyzer to obtain carbon monoxide and hydrogen, which are then used as fuel for power generation.

[0004] The present invention provides a zero-carbon emission high-temperature reversible fuel cell power supply / storage system for LNG receiving terminals, comprising a natural gas reforming unit, a high-temperature reversible fuel cell power generation and supply unit, and a high-temperature reversible fuel cell electrolysis energy storage unit.

[0005] The natural gas reforming unit is provided with a natural gas inlet, a steam inlet and a product outlet. The natural gas inlet is connected to an LNG storage tank and is used to feed the BOG generated by the LNG storage tank into the natural gas reforming unit. The product outlet is connected to the anode of the high-temperature reversible fuel cell power generation device and the cathode of the high-temperature reversible fuel cell power generation device is connected to an oxygen / air inlet pipeline.

[0006] The raw material inlet of the high-temperature reversible fuel cell electrolysis energy storage device is connected to the exhaust gas emission pipeline of the high-temperature reversible fuel cell power generation and energy supply device, and the product gas outlet is connected to the anode of the high-temperature reversible fuel cell power generation and energy supply device.

[0007] The high-temperature reversible fuel cell electrolysis energy storage device is powered by offshore wind power;

[0008] The high-temperature reversible fuel cell power generation device supplies electricity to the LNG receiving station;

[0009] The heat in the fuel cell power supply / storage system comes from the waste heat generated by the high-temperature reversible fuel cell power generation device.

[0010] In the aforementioned fuel cell power supply / storage system, a natural gas purification device is installed on the connecting pipeline between the LNG storage tank and the natural gas reforming unit to desulfurize BOG.

[0011] In the aforementioned fuel cell power supply / storage system, the connecting pipeline between the LNG storage tank and the natural gas purification device, and the connecting pipeline between the natural gas purification device and the natural gas reforming device, are all connected to the waste heat recovery pipeline of the high-temperature reversible fuel cell power generation device, so as to utilize the waste heat generated by the high-temperature reversible fuel cell power generation device.

[0012] In the aforementioned fuel cell power supply / storage system, the steam inlet of the natural gas reforming unit is connected to a steam generator;

[0013] The inlet pipe of the steam generator is connected to the waste heat recovery pipe of the high-temperature reversible fuel cell power generation device, so as to use the waste heat generated by the high-temperature reversible fuel cell power generation device to heat water to obtain steam.

[0014] In the aforementioned fuel cell power supply / storage system, the oxygen / air inlet pipeline is connected to the waste heat recovery pipeline of the high-temperature reversible fuel cell power generation device, so as to utilize the waste heat generated by the high-temperature reversible fuel cell power generation device to heat the air or oxygen.

[0015] In the aforementioned fuel cell power supply / storage system, the exhaust gas emission pipeline of the high-temperature reversible fuel cell power generation device is equipped with an exhaust gas concentration device to concentrate the exhaust gas generated during the power generation process of the high-temperature reversible fuel cell power generation device.

[0016] In the aforementioned fuel cell power supply / storage system, the product gas outlet pipeline of the high-temperature reversible fuel cell electrolysis energy storage device merges with the product outlet pipeline of the natural gas reforming device and is then connected to the high-temperature reversible fuel cell power generation and supply device.

[0017] When using the fuel cell power supply / storage system to supply power to the LNG receiving terminal, the following steps can be followed:

[0018] BOG (mainly composed of natural gas) from the LNG storage tank is heated and purified before entering the natural gas reforming unit, where it undergoes a conversion reaction with the introduced steam to produce reformed gas (mainly composed of carbon monoxide and hydrogen).

[0019] The reformed gas, along with a mixture of carbon monoxide and hydrogen from the high-temperature reversible fuel cell electrolysis energy storage device, enters the anode of the high-temperature reversible fuel cell power generation device to generate electricity, supplying power to the LNG receiving station, and simultaneously generating excess heat; air or oxygen, after being heated, enters the cathode of the high-temperature reversible fuel cell power generation device, where oxygen gains electrons to generate O2. 2- After passing through the electrolyte, it reaches the anode and reacts with carbon monoxide and hydrogen respectively to generate carbon dioxide and water, while losing electrons, thus completing the power generation process of the high-temperature reversible fuel cell power generation device.

[0020] The exhaust gas generated during the power generation process of the high-temperature reversible fuel cell power generation device enters the high-temperature reversible fuel cell electrolysis energy storage device for electrolysis, and the resulting carbon monoxide and hydrogen are mixed with the reformed gas.

[0021] The high-temperature reversible fuel cell electrolysis energy storage device is powered by offshore wind power.

[0022] In the above method, the temperature of the BOG is -155℃ to -120℃;

[0023] The BOG is heated to 200-250°C by waste heat from the high-temperature reversible fuel cell power generation and supply device and then desulfurized. After being heated to 380-480°C by waste heat from the high-temperature reversible fuel cell power generation and supply device, it enters the natural gas reforming device.

[0024] Water is heated by waste heat from the high-temperature reversible fuel cell power generation device to produce water vapor at 320°C to 420°C.

[0025] In the above method, the temperature at the cathode of the high-temperature reversible fuel cell power generation and supply device is 600℃~800℃;

[0026] The electrolysis temperature of the high-temperature reversible fuel cell electrolysis energy storage device is 600℃~800℃.

[0027] The present invention has the following advantages due to the adoption of the above technical solutions:

[0028] (1) The system of the present invention makes full use of BOG of liquefied natural gas as the basic raw material for power generation, greatly reducing the energy required to reliquefy BOG and opening up a new path for the utilization of BOG in LNG receiving terminals.

[0029] (2) The present invention provides a high-temperature reversible fuel cell power supply and storage system, which includes multiple high-temperature reversible fuel cell power generation and power supply devices and high-temperature reversible fuel cell electrolysis energy storage devices. Since the above devices have reversible functions, they can be converted according to the power load of the LNG receiving station and the scale of offshore wind power to ensure the stability of the power supply and storage system.

[0030] (3) The present invention systematically solves the carbon dioxide emission problem of natural gas power generation. It uses the carbon dioxide and water vapor generated by the reaction as raw materials, and uses offshore wind power electrolysis to obtain carbon monoxide and hydrogen, which further provide raw materials for natural gas power generation, turning waste into treasure and achieving a significant improvement in the material utilization rate of the process system.

[0031] (4) The present invention has designed a heat utilization network to make full use of the heat energy produced by the high-temperature reversible fuel cell power generation device, so as to achieve dynamic balance of the system's heat demand and greatly improve the system's energy utilization rate. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the structure of the zero-carbon emission high-temperature reversible fuel cell power supply / storage system for LNG receiving stations according to the present invention.

[0033] The markings in the diagram are as follows:

[0034] 1 LNG storage tank, 2 natural gas purification unit, 3 natural gas reforming unit, 4 high-temperature reversible fuel cell power generation and supply unit, 5 tail gas concentration unit, 6 high-temperature reversible fuel cell electrolysis energy storage unit, 7 offshore wind power supply unit, 8 steam generation unit. Detailed Implementation

[0035] The present invention will be further described below with reference to the accompanying drawings, but the present invention is not limited to the following embodiments.

[0036] like Figure 1 As shown in the diagram, the novel high-temperature reversible energy supply and storage system for a clean and efficient LNG receiving station with zero carbon emissions provided by the present invention includes an LNG storage tank 1, a natural gas purification device 2, a natural gas reforming device 3, a high-temperature reversible fuel cell power generation and supply device 4, a tail gas concentration device 5, a high-temperature reversible fuel cell electrolysis energy storage device 6, an offshore wind power supply device 7, and a steam generator 8.

[0037] LNG storage tank 1, natural gas purification unit 2, and natural gas reforming unit 3 are connected in sequence. The steam inlet of natural gas reforming unit 3 is connected to steam generator 8, and the product gas outlet is connected to the anode of high-temperature reversible fuel cell power generation unit 4. The cathode of high-temperature reversible fuel cell power generation unit 4 is connected to the oxygen / air inlet pipeline. The feed inlet of high-temperature reversible fuel cell electrolysis energy storage unit 6 is connected to the exhaust gas outlet pipeline of high-temperature reversible fuel cell power generation unit 4. This exhaust gas outlet pipeline is connected to exhaust gas concentration unit 5. The product gas outlet of high-temperature reversible fuel cell electrolysis energy storage unit 6 merges with the product gas outlet of natural gas purification unit 2. Offshore wind power supplies power to high-temperature reversible fuel cell electrolysis energy storage unit 6 via offshore wind power supply unit 7.

[0038] The heat of the fuel cell power supply / storage system of this invention comes from the waste heat generated by the high-temperature reversible fuel cell power generation device 4, and the heating is achieved through the following combination:

[0039] The pipeline between LNG storage tank 1 and natural gas purification device 2 is connected to the waste heat recovery pipeline of high-temperature reversible fuel cell power generation device 4, which is used to receive waste heat Q1 for heating BOG.

[0040] The pipeline between the natural gas purification unit 2 and the natural gas reforming unit 3 is connected to the waste heat recovery pipeline of the high-temperature reversible fuel cell power generation and supply unit 4, which is used to receive waste heat Q3 for heating natural gas.

[0041] The oxygen / air inlet pipe connected to the cathode of the high-temperature reversible fuel cell power generation device 4 is connected to the waste heat recovery pipe of the high-temperature reversible fuel cell power generation device 4 to receive waste heat Q4 for heating air / oxygen.

[0042] The inlet pipe of the steam generator 8 is connected to the waste heat recovery pipe of the high-temperature reversible fuel cell power generation device 4 to receive waste heat Q4 and use it to heat water to obtain steam.

[0043] The working process of the clean and efficient zero-carbon emission novel high-temperature reversible energy supply and storage system for LNG receiving terminals of this invention is as follows:

[0044] Utilizing 1000Nm 3BOG gas volatilized from an LNG storage tank at -130℃ is heated to 214℃ by waste heat Q1 from the high-temperature reversible fuel cell power generation unit 4, and then enters the natural gas purification unit 2 for desulfurization. The desulfurized natural gas is further heated to 413℃ by waste heat Q3 from the high-temperature reversible fuel cell power generation unit 4. The steam generator 8 uses waste heat Q2 from the high-temperature reversible fuel cell power generation unit 4 to heat water from outside the system to obtain steam at 385℃. The heated natural gas is mixed with 2140 kg / h of steam and enters the natural gas reforming unit 3 for a conversion reaction to obtain reformed gas (mainly composed of carbon monoxide and hydrogen).

[0045] 5000Nm 3 Air, heated by waste heat Q4 from the high-temperature reversible fuel cell power generation device 4, enters the cathode (reaction temperature 720°C) of the device. The reformed gas, mixed with carbon monoxide and hydrogen from the high-temperature reversible fuel cell electrolysis energy storage device, is introduced into the anode of the device at a gradually decreasing ratio of 1:1 to 1:5, generating a stable power output of 0.5MW to 2MW, while simultaneously producing excess heat of 0.4MW to 1.5MW, providing a heat source for the system of this invention.

[0046] The exhaust gas generated during the power generation process of the high-temperature reversible fuel cell power generation device 4 is concentrated by the exhaust gas concentrator 5 to obtain high-purity carbon dioxide and water vapor, which then enter the high-temperature reversible fuel cell electrolysis energy storage device 6 (reaction temperature 720℃). A 5MW offshore wind power system provides electricity to the high-temperature reversible fuel cell electrolysis energy storage device 6 via the offshore wind power supply device 7, and electrolyzes the incoming carbon dioxide and water vapor to obtain carbon monoxide and hydrogen, which are then mixed with reformed gas in a certain proportion and fed into the high-temperature reversible fuel cell power generation device 4 to convert into stable electrical energy.

Claims

1. A zero-carbon emission high-temperature reversible fuel cell power supply / storage system for LNG receiving terminals, comprising a natural gas reforming unit, a high-temperature reversible fuel cell power generation unit, and a high-temperature reversible fuel cell electrolysis energy storage unit; The natural gas reforming unit is provided with a natural gas inlet, a steam inlet and a product outlet. The natural gas inlet is connected to an LNG storage tank and is used to feed the BOG generated by the LNG storage tank into the natural gas reforming unit. The product outlet is connected to the anode of the high-temperature reversible fuel cell power generation device and the cathode of the high-temperature reversible fuel cell power generation device is connected to an oxygen / air inlet pipeline. The raw material inlet of the high-temperature reversible fuel cell electrolysis energy storage device is connected to the exhaust gas emission pipeline of the high-temperature reversible fuel cell power generation and energy supply device, and the product gas outlet is connected to the anode of the high-temperature reversible fuel cell power generation and energy supply device. The high-temperature reversible fuel cell electrolysis energy storage device is powered by offshore wind power; The high-temperature reversible fuel cell power generation device supplies electricity to the LNG receiving station; The heat of the fuel cell power supply / storage system comes from the waste heat generated by the high-temperature reversible fuel cell power generation device. The steam inlet of the natural gas reforming unit is connected to a steam generator; The inlet pipe of the steam generator is connected to the waste heat recovery pipe of the high-temperature reversible fuel cell power generation and supply device. The product gas outlet pipeline of the high-temperature reversible fuel cell electrolysis energy storage device merges with the product outlet pipeline of the natural gas reforming device and is then connected to the high-temperature reversible fuel cell power generation and supply device.

2. The fuel cell power supply / storage system according to claim 1, characterized in that: A natural gas purification device is installed on the pipeline connecting the LNG storage tank and the natural gas reforming unit.

3. The fuel cell power supply / storage system according to claim 2, characterized in that: The connecting pipeline between the LNG storage tank and the natural gas purification device, and the connecting pipeline between the natural gas purification device and the natural gas reforming device, are all connected to the waste heat recovery pipeline of the high-temperature reversible fuel cell power generation and supply device.

4. The fuel cell power supply / storage system according to any one of claims 1-3, characterized in that: The oxygen / air inlet pipeline is connected to the waste heat recovery pipeline of the high-temperature reversible fuel cell power generation device.

5. The fuel cell power supply / storage system according to any one of claims 1-3, characterized in that: The exhaust gas concentrator is installed on the exhaust gas emission pipeline of the high-temperature reversible fuel cell power generation device.

6. A method for supplying power to an LNG receiving station using the fuel cell power supply / storage system according to any one of claims 1-5, comprising the following steps: BOG from the LNG storage tank is heated and purified before entering the natural gas reforming unit, where it undergoes a conversion reaction with the introduced steam to obtain reformed gas. The reformed gas, along with a mixture of carbon monoxide and hydrogen from the high-temperature reversible fuel cell electrolysis energy storage device, enters the anode of the high-temperature reversible fuel cell power generation device to generate electricity, supplying power to the LNG receiving station, and simultaneously generating excess heat; air or oxygen, after being heated, enters the cathode of the high-temperature reversible fuel cell power generation device, where oxygen gains electrons to generate O2. 2- After passing through the electrolyte, it reaches the anode and reacts with carbon monoxide and hydrogen respectively to generate carbon dioxide and water, while losing electrons, thus completing the power generation process of the high-temperature reversible fuel cell power generation device. The exhaust gas generated during the power generation process of the high-temperature reversible fuel cell power generation device enters the high-temperature reversible fuel cell electrolysis energy storage device for electrolysis, and the resulting carbon monoxide and hydrogen are mixed with the reformed gas. The high-temperature reversible fuel cell electrolysis energy storage device is powered by offshore wind power.

7. The method according to claim 6, characterized in that: The temperature of the BOG is -155℃ to -120℃; The BOG is heated to 200-250°C by waste heat from the high-temperature reversible fuel cell power generation and supply device and then desulfurized. After being heated to 380-480°C by waste heat from the high-temperature reversible fuel cell power generation and supply device, it enters the natural gas reforming device. Water is heated by waste heat from the high-temperature reversible fuel cell power generation device to produce water vapor at 320°C to 420°C.

8. The method according to claim 6 or 7, characterized in that: The temperature at the cathode of the high-temperature reversible fuel cell power generation and supply device is 600℃~800℃; The electrolysis temperature of the high-temperature reversible fuel cell electrolysis energy storage device is 600℃~800℃.

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