Method for generating power through high-temperature and high-pressure water and steam generated by closed water body in deep underwater space

Abstract

The invention discloses a method for generating high-temperature and high-pressure steam for power generation in a closed water body of a deep underwater space of a reservoir, a lake and an ocean by using green electricity. An underwater storage tank, electric heating equipment, a water supplementing pipeline, an output pipeline, steam pressurizing and heating equipment and steam turbine power generation equipment are included. An underwater storage tank is arranged at the water bottom, an electric heater is installed in the storage tank, a water supplementing pipeline is communicated to the bottom of the storage tank from the water surface, an output pipeline is arranged at the top of the storage tank and connected with a steam pressurizer and a steam heater which are driven by green electricity, output high-temperature and high-pressure superheated steam drives a steam turbine generator to generate electricity, and stable and balanced electric power supply is carried out. According to the technology, the underwater space is fully utilized, by means of the natural pressure of the deep water body, redundant wind, photoelectric energy and other renewable electric power are consumed locally to heat the large-scale water body to generate high-temperature and high-pressure steam, and long-time and cross-seasonal heat storage and power generation are achieved. And the method has very important significance in improving the utilization rate of new energy electric energy and accelerating the realization of the dual-carbon target of 3060.

Description

Technical Field

[0001] The present application relates to the field of renewable energy storage and power generation, and in particular to a method for generating power by using a closed water body in a deep underwater space to generate high-temperature and high-pressure water and steam. Background Art

[0002] In conventional thermal power plants, boilers consume fossil energy such as coal and natural gas to generate high-temperature, high-pressure steam for power generation. The chemical energy of the fuel is first converted into the thermal energy of steam in the boiler. The steam enters the steam turbine generator set and is converted into mechanical energy, which drives the turbine to operate and drives the generator to generate electricity, completing the conversion of thermal energy and mechanical energy into electrical energy. The steam temperature and pressure required for power generation consume a large amount of primary energy and pollute the environment. Coal accounts for more than 60% of power generation in my country, which is the focus of reducing carbon emissions. In the context of carbon peak and carbon neutrality, it is necessary to significantly reduce the power generation of coal-fired power plants through the substitution of renewable energy.

[0003] The pressure of deep water bodies such as reservoirs, lakes, and oceans is naturally generated by the gravity of water, and increases with the depth. In a deep water environment of 100 meters, the pressure exceeds 1MPa. According to the thermodynamic properties of water in a high-pressure state (see Table 1), the pressure of water can be used in a deep water environment to change the physical state of water, thereby generating high-temperature and high-pressure water. However, the research and application of using deep underwater space enclosed water bodies to generate high-temperature and high-pressure water and steam power generation is still a blank.

[0004] The western and southwestern regions of my country are famous for their rich hydropower resources in China and even in the world. According to incomplete statistics, dozens of large and even giant hydropower stations have been planned and built in the upper reaches of the Yangtze River and the Yellow River, ranking among the top in the world. The maximum dam height is more than 300 meters, the maximum reservoir capacity is more than 20 billion cubic meters, and the water depth is more than 100 meters. There are good conditions for using water bodies to store heat across seasons and using deep underwater space to enclose water bodies to generate high-temperature and high-pressure water and steam for power generation.

[0005] my country's marine land area is about 3 million square kilometers, and the marine rights and interests area has reached about 2 million square kilometers. The average depth of the Bohai Sea and the Yellow Sea is below 50 meters, the average water depth of the East China Sea and the South China Sea is between 100 and 1,000 meters, and the deepest point in the South China Sea can reach 5,377 meters, showing a vast and usable deep underwater space. With the rapid development of offshore wind farms, the use of wind power surplus electricity to store heat across seasons and the use of deep closed water bodies to generate high-temperature and high-pressure water and steam for power generation have broad development prospects.

[0006] Therefore, inventing a method of using deep underwater space to enclosed water bodies to generate high-temperature and high-pressure water and steam for cross-seasonal heat storage and power generation is of great significance for improving the utilization rate of new energy electricity and accelerating the realization of the "3060" dual carbon goals.

[0007] Table 1: Thermodynamic properties of saturated water and saturated water vapor pressure temperature pressure temperature pressure temperature pressure temperature MPa ℃ MPa ℃ MPa ℃ MPa ℃ 0.1 99.53 1.1 184.06 3 233.84 13 330.81 0.2 120.23 1.2 187.96 4 250.33 14 336.63 0.3 133.54 1.3 191.6 5 263.92 15 342.12 0.4 143.62 1.4 195.04 6 275.56 16 347.32 0.5 151.85 1.5 198.28 7 285.8 17 352.26 0.6 158.84 1.6 201.37 8 294.8 18 356.96 0.7 164.96 1.7 204.3 9 303.31 19 361.44 0.8 170.42 1.8 207.1 10 301.96 20 365.71 0.9 175.36 1.9 209.79 11 318.04 21 369.79 1 179.88 2 212.37 12 324.64 22 373.68 Summary of the invention

[0008] The present invention provides a method for generating electricity by generating high-temperature and high-pressure water and steam using a closed water body in a deep underwater space, which can solve the problem of long-term, large-scale, cross-season energy and electricity storage under certain conditions. The characteristic of this technology is that it utilizes the natural pressure of a closed water body in a deep underwater space, and utilizes renewable electricity such as wind power and photovoltaic power and off-peak electricity to heat a large-scale closed water body in a deep underwater space into high-temperature and high-pressure water to achieve cross-season heat storage. In the process of being transported to the ground, the high-temperature and high-pressure water flashes into high-temperature steam, which is converted into high-temperature and high-pressure superheated steam through steam pressurization using green electricity as energy and heating by a high-temperature molten salt heat storage system. After meeting the requirements for power generation, it enters a steam turbine to generate electricity. The above-mentioned whole process does not consume primary energy and does not generate carbon emissions. Therefore, using deep closed high-pressure water and green electricity in nature to generate high-temperature and high-pressure steam for power generation is a zero-carbon technology, which is in line with the direction of green and low-carbon, and is of great significance to promoting energy technology revolution and technological innovation.

[0009] Since the space of deep water bodies such as reservoirs, lakes, and oceans is quite large, the volume of the single heat storage tank provided by this patented technology is large enough and the number of heat storage tanks is sufficient, which can achieve a stable and balanced power supply across seasons to a certain extent. It alleviates the difficulties of absorbing a high proportion of local renewable electricity and large-scale cross-seasonal energy storage and electricity storage, and also expands space for the development of wind power and photovoltaics, and increases the flexibility of power plants and power grids. It is of great significance to my country's energy security, promoting green and low-carbon energy transformation, and promoting high-quality energy development.

[0010] In order to achieve the above object, the present invention provides the following technical solutions: A method for generating electricity by generating high-temperature and high-pressure water and steam using a closed water body in a deep underwater space, comprising: an underwater storage tank, an electric heating device, a water supply pipe, an output pipe, a steam pressurizing or heating device, and a steam turbine power generation device. The underwater storage tank is placed at the bottom of a reservoir, lake, or ocean. The water supply pipe runs from the water surface to the bottom of the storage tank and is equipped with a pressure pump. The output pipe is installed on the top of the water tank and is connected to the steam pressurizing and heating device. The output high-temperature and high-pressure steam enters the steam turbine to drive the generator to generate electricity, thereby realizing cross-seasonal heat storage and power generation.

[0011] The underwater storage tank is made of corrosion-resistant and high-temperature resistant materials, and the outer surface is covered with a heat-insulating layer. The tank body is placed at the bottom of a reservoir, lake, or ocean. According to the relationship between the pressure and the temperature of saturated water shown in the thermodynamic property table of high-pressure water (see Table 1), when the water depth is 30-100 meters, medium-temperature and medium-pressure water and steam of 120-180°C can be provided, when the water depth is 100-500 meters, high-temperature and high-pressure water and steam of 180-250°C can be provided, and when the water depth is 2200 meters, the water pressure reaches 22MPa, and high-temperature and high-pressure steam with a critical temperature of 373.588°C can be provided. Since the inside and outside of the storage tank are all water and the pressure is the same, even though it is in an environment of a water depth of more than 100 meters and a pressure of more than 1Ma, when the static working condition of electric heating is adopted, the storage tank volume is large but the tank body is not under pressure, and the pressure resistance requirement of the tank body is not high. Compared with the ground storage tank, the processing difficulty and manufacturing cost of the tank body can be greatly reduced. The pressure-bearing design of the tank body only needs to meet the pressure added to the tank by the water replenishment pump when replenishing water.

[0012] The underwater storage tank is divided into two types: a heating tank and a heat storage tank. The heating tank is equipped with an electric heating device, which can use the surplus electricity or valley electricity of wind power and photovoltaic power to heat the water in the tank to a design temperature lower than the saturation temperature at any time to ensure that the water in the tank does not vaporize. The storage tank can also be designed as a pressure vessel to heat the water in the tank to a temperature higher than the saturation temperature corresponding to the underwater pressure. After the water in the heating tank is heated to the design temperature, it is transported to the heat storage tank for storage. Due to the huge underwater volume of reservoirs, lakes, and oceans, the number of heat storage tanks that can be accommodated is huge, which can achieve large-capacity cross-season storage of high-temperature and high-pressure water. Combined with steam pressurization or heating equipment that consumes green electricity, a stable and balanced power supply can be completed to achieve cross-seasonal electricity storage. The heat storage tank will inevitably produce heat loss during the heat storage process over a long period of time, resulting in a drop in water temperature. Auxiliary electric heating equipment is required to be used regularly for cyclic heating to reach and maintain the design water temperature during the cross-season heat storage process. The auxiliary electric heating equipment can be set in the heat storage tank or set separately. Its function is to heat the water in the heat storage tank in a small range.

[0013] A high temperature resistant flexible diaphragm is arranged inside the underwater storage tank to divide the space inside the tank into two parts, the upper and lower parts, to separate the high temperature water and the low temperature water, to avoid mixing and generating heat exchange when the cold and hot water are replaced, which reduces the utilization efficiency of the storage tank. The non-contact replacement of the high temperature water and the low temperature water in the tank is completed by connecting the pipes and valves between the heating tank and the heat storage tank, and the auxiliary electric heating equipment is used to circulate and increase the temperature of the heat storage tank.

[0014] The electric heating device is a universal electric water heater and is a mature technology.

[0015] The water supply pipe is a high-pressure pipe that runs from the water surface to the bottom of the heating tank. Its pressure rating should be higher than the water pressure at the location of the heating tank. A pressure pump is installed on the pipe to input treated and heated water into the heating tank from the bottom. The pressure increased by the pressure pump causes the high-temperature and high-pressure water in the tank to be discharged from the output pipe.

[0016] The output pipe is installed on the top of the storage tank. The pressure generated by the operation of the booster pump causes the high-temperature and high-pressure water in the tank to be discharged from the output pipe. The output pipe has two outlets. Outlet 1 is connected to the steam pressurization and heating equipment. The high-temperature and high-pressure superheated steam output after pressurization and heating enters the steam turbine to drive the generator to generate electricity. Outlet 2 is connected to the heat storage tank to transport the high-temperature and high-pressure water to the heat storage tank to achieve cross-seasonal heat storage.

[0017] The water supply pipe and the output pipe can adopt the method of inner and outer outer pipes to reduce heat loss.

[0018] The steam pressurizing and heating equipment described is a mature technology.

[0019] The steam turbine power generation equipment described is a mature technology.

[0020] The beneficial effects of the present invention are: 1. The implementation of this patent has greatly improved the ability to absorb renewable energy locally. China has become the world's largest energy producer and consumer, and its installed capacity of wind power and solar power ranks first in the world. In the future, renewable energy will become China's main source of energy. However, the bottleneck problem of wind and solar abandonment has seriously hindered the development and utilization of renewable energy. The implementation of this patented technology utilizes deep underwater spaces such as reservoirs, lakes, and oceans to generate high-temperature and high-pressure steam power generation through green electricity heating and other methods, and absorbs excess wind and photovoltaic energy on a large scale, realizing long-term energy storage and cross-seasonal heat and electricity storage. It is of great significance to promote energy technology revolution and technological innovation.

[0021] 2. It optimizes the process of using fossil energy from boilers in conventional thermal power plants to generate high-temperature and high-pressure steam for power generation. The heat source does not consume primary energy, does not emit carbon dioxide, does not occupy land, does not occupy ground space, does not generate pollution, and is in line with the direction of green and low-carbon.

[0022] 3. This patent divides underwater storage tanks into heating tanks and heat storage tanks, which can greatly increase the heat storage capacity and provide a stable and balanced power supply on the premise of cross-seasonal heat storage, thereby realizing cross-seasonal power storage.

[0023] 4. This patent sets a high temperature resistant flexible diaphragm inside the underwater storage tank to separate high temperature water and low temperature water, so as to avoid mixing and generating heat exchange to reduce the utilization efficiency of the storage tank. The non-contact replacement of high temperature water and low temperature water in the tank is completed by connecting the pipes and valves between the heating tank and the heat storage tank, and the auxiliary electric heating equipment is used to circulate and heat the heat storage tank. It can reach and maintain the designed water temperature during the cross-season heat storage process.

[0024] 5. This patent uses water as the energy storage medium. Due to the increase in the specific heat capacity of water under high pressure, the total amount of energy storage is more than doubled compared to that under normal pressure, which can achieve high-density thermal energy storage. At the same time, water is used as a circulating working fluid, which is safe, green and low-cost. Compared with the existing technology that uses normal pressure low-temperature water or phase change materials to store thermal energy, it has the characteristics of high cost performance and low cost. 6. This patent places storage tanks in deep underwater spaces, and with the help of the natural pressure of the enclosed water body in the deep underwater space, uses renewable electricity such as wind power and photovoltaics to heat the large-scale water body enclosed in the deep underwater space into high-temperature and high-pressure water to achieve cross-seasonal heat and electricity storage, making full use of the underwater space, while reducing the pressure on the storage tank and the cost of the storage tank and foundation. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the process of the present invention; Figure 2 It is a schematic diagram of the underwater equipment of the present invention; Figure 3 It is a schematic diagram of the underwater heat storage tank of the present invention; Reference numerals: 1. Underwater storage tank; 2. Pressure pump; 3. Electric heating equipment; 4. Output pipeline; 5. Steam compressor; 6. Steam heater; 7. Steam turbine; 8. Generator; 9. Water supply pipeline; 10 Flexible diaphragm; 11. Heating tank; 12. Heat storage tank; 13. Auxiliary electric heating equipment. DETAILED DESCRIPTION

[0026] The technical solution in this application will be described in detail below in conjunction with the accompanying drawings.

[0027] A method for generating electricity by using a closed water body in a deep underwater space to generate high-temperature and high-pressure water and steam, comprising: an underwater storage tank 1, an electric heating device 3, a water supply pipeline 9, an output pipeline 4, a steam compressor 5, a steam heater 6, a steam turbine 7, a generator 8, a flexible diaphragm 10, a heating tank 11; a heat storage tank 12; and an auxiliary electric heating device 13.

[0028] The underwater storage tank 1 is placed at the bottom of a reservoir, lake or ocean. A water supply pipe 9 runs from the water surface to the bottom of the storage tank and is installed with a pressure pump. An output pipe 4 is installed on the top of the water tank. The output pipe 4 is connected to a steam compressor 5 and then to a steam heater 6. The output high-temperature and high-pressure steam enters a steam turbine 7 to drive a generator 8 to generate electricity, thereby realizing cross-seasonal heat storage and power generation.

[0029] The water depth of the underwater storage tank installation location of this embodiment is 100 meters below the water surface, the underwater water pressure is 1MPa, and the pressure in the underwater storage tank is also 1MPa. According to Table 1 "Thermodynamic properties of saturated water and saturated water vapor", the saturation temperature of water at a pressure of 1MPa is 179.88℃ (approximately equal to 180℃). Therefore, the surplus electricity or valley electricity of wind power and photovoltaic power can be used to heat the water in the underwater heating tank to the design temperature of 170℃ through the electric heating device 3. At this time, the internal and external pressures of the heating tank are balanced and the tank body is not under pressure. After the water in the heating tank is heated to the design temperature, it is transported to the heat storage tank for storage. Due to the huge underwater volume of the reservoir, the number of heat storage tanks that can be accommodated is huge, which can realize large-capacity cross-season storage of high-temperature and high-pressure water and realize cross-season heat storage.

[0030] This embodiment has multiple groups of underwater storage tanks, each group of storage tanks has a heating tank and multiple heat storage tanks. The non-contact replacement of high-temperature water and low-temperature water in the tank is completed by connecting the pipes and valves between the heating tank and the heat storage tank, and the auxiliary electric heating equipment is used to circulate and increase the temperature of the heat storage tank. There are four working conditions for underwater storage tanks: 1. Heating condition, 2. Heat storage condition, 3. Heat release condition, and 4. Power generation condition.

[0031] 1. Heating conditions: Initial temperature, the heating tank 11 and the heat storage tank 12 are both in a low temperature state, the electric heating device 3 in the heating tank 11 starts to operate, and the water in the tank is heated to the design temperature.

[0032] Auxiliary heating: The heat storage tank will inevitably generate heat loss during the long-term heat storage process, resulting in a drop in water temperature. Auxiliary electric heating equipment is required to be used regularly for cyclic heating to reach and maintain the designed water temperature during the cross-season heat storage process. In this embodiment, each heat storage tank group is provided with an auxiliary electric heating device, which is connected to the heat storage tank through a pipeline valve. When the water temperature in a tank drops to a certain temperature, the auxiliary electric heating device starts to operate, cyclically heats the water in the storage tank, and stops operating when the designed temperature is reached.

[0033] 2. Heat storage condition: The high-temperature hot water in the heating tank 11 is replaced with the low-temperature water in the heat storage tank 12-1 by connecting the pipes and valves between the heating tank and the heat storage tank. The electric heating device 3 in the heating tank 11 is operated again to reach the design temperature, and then the high-temperature hot water is replaced into the heat storage tank 12-2, and so on. The hot water replacement of multiple heat storage tanks is completed within a period of time, realizing long-term and cross-season heat storage.

[0034] 3. Heat release condition: The system's supplementary water enters the bottom of the heat storage tank 12-1 through the water supply pipe and the pressure pump, and the high-temperature and high-pressure water in the heat storage tank 12-1 enters the output pipe 4 through the pipe on the top. Due to the existence of the diaphragm, there is no phenomenon of mixing and cooling of the cold and hot water in the heat storage tank. In the process of being transported to the ground, the water pressure in the pipeline gradually decreases, and the high-temperature and high-pressure water flashes into high-temperature and low-pressure steam and is transported to the steam pressurization and heating equipment. The water temperature at the bottom of the heat storage tank returns to the initial state.

[0035] 4. Power generation conditions: High-temperature, low-pressure steam enters the steam compressor 5 through the output pipeline 4 and becomes high-temperature, high-pressure steam, and then enters the steam heater. The output high-temperature, high-pressure superheated steam enters the steam turbine 6 to drive the generator 8 to generate electricity, thereby realizing cross-seasonal heat storage and power generation.

[0036] The steam compressor is a steam pressurizing device driven by green electricity, and the steam heater is a high-temperature molten salt heat storage device. Steam is heated and pressurized to become high-temperature and high-pressure superheated steam, which enters the steam turbine to generate electricity after meeting the requirements of power generation. The above whole process does not consume primary energy and does not produce carbon emissions.

[0037] When the system enters the power generation condition, the exhaust steam condensate of the steam turbine replenishes the heat storage tank 12 through the water replenishment pipe, and the high-temperature and high-pressure water stored in the tank flows to the water surface through the output pipe. The water pressure gradually decreases during the rising process, and the water temperature in the pipe is higher than the saturation temperature of the corresponding pressure, and flash evaporation occurs. The low-pressure and high-temperature steam-water mixed steam output from the pipe enters the steam compressor 5 and the steam heater 6. The high-temperature and high-pressure superheated steam output after pressurization and heating meets the requirements of power generation, and enters the steam turbine 7 to drive the generator 8 to generate electricity. By switching the heat storage tank 12 in this way, a stable and balanced power supply can be achieved.

[0038] The present invention involves electric heating equipment and steam heating and pressurizing equipment, all of which are driven by green electricity and are mature technologies. Therefore, this embodiment does not describe the relevant process flow and auxiliary equipment involved. The high temperature, low temperature, high pressure and low pressure involved in the textual description of the present invention are all relative, without quantitative restrictions, and need to be implemented in accordance with relevant specifications.

Claims

1. A method for generating electricity by using a deep underwater space enclosed water body to generate high temperature and high pressure water and steam, characterized in that: include: Underwater storage tanks, electric heating equipment, water supply pipes, output pipes, steam pressurization or heating equipment, and steam turbine power generation equipment. Underwater storage tanks are placed at the bottom of reservoirs, lakes, and oceans. Electric heating equipment is installed in the tanks to heat the water. The water supply pipes run from the water surface to the bottom of the tanks and are equipped with a pressure pump. The output pipes are installed on the top of the tanks, connected to the steam compressor and then to the steam heater. The high-temperature and high-pressure superheated steam output enters the steam turbine to drive the generator to generate electricity, realizing cross-seasonal heat storage and power generation; This technology leverages the natural pressure of enclosed water bodies in deep underwater spaces, and uses renewable electricity such as wind power and photovoltaics, as well as off-peak electricity, to heat large-scale enclosed water bodies in deep underwater spaces to output high-temperature and high-pressure steam, achieving cross-seasonal heat storage and power generation.

2. The method for generating electricity by using high-temperature and high-pressure water and steam in a closed water body in a deep underwater space according to claim 1, characterized in that: The underwater storage tank is made of corrosion-resistant and high-temperature-resistant materials, the outer surface of which is covered with a heat-insulating layer, and the tank body is placed at the bottom of a reservoir, lake or ocean.

3. The method for generating electricity by using high-temperature and high-pressure water and steam in a closed water body in a deep underwater space according to claim 1, characterized in that: The underwater storage tanks are divided into heating tanks and heat storage tanks, forming an underwater storage tank group; the heating tank is equipped with an electric heating device, which can use the surplus electricity or off-peak electricity of wind power and photovoltaic power to heat the water in the tank to a design temperature lower than the saturation temperature; the underwater storage tank assembly is equipped with auxiliary electric heating equipment to circulate and heat the heat storage tank.

4. The method for generating electricity by using high-temperature and high-pressure water and steam in a closed water body in a deep underwater space according to claim 1, characterized in that: A high-temperature resistant flexible diaphragm is arranged inside the underwater storage tank to divide the space inside the tank into two parts, the upper and lower parts, to separate the high-temperature water and the low-temperature water to avoid mixing when the cold and hot water are replaced. The contactless replacement of the high-temperature water and the low-temperature water in the tank is completed by connecting the pipes and valves between the heating tank and the heat storage tank.

5. The method for generating electricity by using high-temperature and high-pressure water and steam in a closed water body in a deep underwater space according to claim 1, characterized in that: The water supply pipeline is a high-pressure pipeline that runs from the water surface to the bottom of the storage tank and is equipped with a pressure pump to input the treated and heated water into the heating tank from the bottom.

6. The method for generating electricity by using high-temperature and high-pressure water and steam in a closed water body in a deep underwater space according to claim 1, characterized in that: The output pipe is installed on the top of the water tank. The output pipe has two outlets, which are respectively connected to the steam pressurization and heating equipment and the heat storage tank, and the superheated steam that has been pressurized and heated is transported to the turbine to drive the generator to generate electricity and the heat storage tank, thereby realizing cross-seasonal heat storage power generation.

7. The method for generating electricity by using high-temperature and high-pressure water and steam in a closed water body in a deep underwater space according to claim 1, characterized in that: The water supply pipe and the output pipe can adopt the method of inner and outer outer pipes to reduce heat loss.

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