A power generation system using magnesium as fuel and a working method thereof

Abstract

The present invention discloses a power generation system using magnesium as fuel and a working method thereof. The system comprises a magnesium fuel electrolysis preparation subsystem, a magnesium combustion and combustion product collection subsystem and a steam Rankine cycle power generation subsystem. The present invention effectively couples magnesium fuel-based energy storage, magnesium combustion power generation, steam Rankine cycle and magnesium oxide electrolysis regeneration, and has the advantages of high energy storage density, long energy storage cycle to achieve permanent storage, fuel cycle regeneration without consumption, and convenience for global energy trade.

Description

Technical Field

[0001] The invention belongs to the technical field of green cycle power generation and advanced energy storage, and specifically relates to a power generation system using magnesium as fuel and a working method thereof. Background Art

[0002] As global air pollution and climate warming become increasingly severe, traditional power generation systems based on fossil energy will face unprecedented pressure and challenges. From a global perspective, countries are working hard to increase the proportion of renewable energy generation in their power structure. In the future, the development trend of the world's energy sector will inevitably be the gradual replacement of fossil energy by renewable energy. However, due to its own intermittent, unstable and uncertain characteristics, renewable energy has seriously hindered the development of renewable energy power generation. In the future, to achieve the replacement of fossil energy by renewable energy, it is necessary to rely on the development and support of large-scale and long-cycle energy storage technology.

[0003] At present, research in the field of energy storage technology is very active, and various energy storage technologies are developing rapidly, such as pumped storage, compressed air storage, lithium battery storage, supercapacitor storage, flywheel storage, hydrogen storage, etc. However, existing energy storage technologies are difficult to simultaneously meet the requirements of high energy storage density, mobility, low self-consumption loss and global energy trade. Therefore, it is necessary to develop a new energy storage technology to enable renewable energy generation to develop in a deeper and wider direction worldwide. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a power generation system using magnesium as fuel and a working method thereof. The system effectively couples magnesium fuel energy storage, magnesium combustion power generation, steam Rankine cycle and magnesium oxide electrolysis regeneration, and has the advantages of high energy storage density, long energy storage period to achieve permanent storage, fuel cycle regeneration without consumption, and facilitation of global energy trade.

[0005] In order to achieve the above object, the present invention adopts the following technical scheme:

[0006] A power generation system using magnesium as fuel, comprising a magnesium fuel electrolysis preparation subsystem, a magnesium combustion and combustion product collection subsystem and a steam Rankine cycle power generation subsystem;

[0007] The magnesium fuel electrolysis preparation subsystem includes a magnesium oxide electrolysis device 1, a surplus renewable energy power supply 2 in the power grid, a cooler 3 and a magnesium powder storage tank 4; the electrolyte inlet of the magnesium oxide electrolysis device 1 is connected to the MgO material inlet, the flux inlet of the magnesium oxide electrolysis device 1 is connected to the flux delivery pipeline, the power supply of the magnesium oxide electrolysis device 1 is connected to the surplus renewable energy power supply 2 in the power grid, the cathode of the magnesium oxide electrolysis device 1 is connected to the hot side inlet of the cooler 3, and the hot side outlet of the cooler 3 is connected to the fuel inlet of the magnesium powder storage tank 4;

[0008] The magnesium combustion and combustion product collection subsystem comprises a magnesium powder burner 5, a boiler 6, a cyclone separator 7, a heat exchanger 8, a dust collector 9 and a chimney 10 which are sequentially connected to a magnesium powder storage tank 4 of the magnesium fuel electrolysis preparation subsystem; magnesium powder and air are mixed through the magnesium powder burner 5 and then enter the boiler 6 for combustion, and the combustion reaction equation is 2Mg+O2=2MgO. A large amount of heat is released by the combustion reaction, part of which is absorbed by the working medium in the heating surface around the boiler 6, and the other part of the heat is accompanied by the flue gas through the cyclone separator 7 and then enters the heat exchanger. The gas is absorbed by the working medium in the heat exchanger 8, the flue gas outlet of the boiler 6 is connected to the material inlet of the cyclone separator 7, the solid combustion product MgO in the flue gas is separated by the cyclone separator 7 and then collected from the bottom, the gas outlet of the cyclone separator 7 is connected to the hot side inlet of the heat exchanger 8, the hot side outlet of the heat exchanger 8 is connected to the inlet of the dust collector 9, the flue gas outlet of the dust collector 9 is connected to the inlet of the chimney 10, the small amount of fine MgO particles remaining in the flue gas are collected and recycled by the dust collector 9, and the flue gas is finally discharged into the atmosphere through the chimney 10;

[0009] The steam Rankine cycle power generation subsystem includes a steam turbine 11, a generator 12, a condenser 13 and a feed water pump 14; the newly added power cycle working medium water is mixed with the condensed water recovered by condensation in the condenser 13 and connected to the working medium inlet of the feed water pump 14, the working medium outlet of the feed water pump 14 is connected to the cold side inlet of the heat exchanger 8, the cold side outlet of the heat exchanger 8 is connected to the power cycle working medium inlet of the boiler 6, the power cycle working medium outlet of the boiler 6 is connected to the inlet of the steam turbine 11, and the steam The working fluid outlet of the turbine 11 is connected to the working fluid inlet of the condenser 13, and the generator 12 is coaxially connected to the steam turbine 11; the newly added power cycle working fluid water is mixed with the condensate recovered by condensation in the condenser 13 and then enters the feed water pump 14 for pressurization, and then enters the heat exchanger 8 to absorb heat. The working fluid after absorbing heat and heating enters the boiler 6, and continues to absorb heat and heat in the boiler 6 to become high-temperature superheated steam. The high-temperature superheated steam expands and does work in the steam turbine 11 and drives the generator 12 to rotate and generate electricity, and then enters the condenser 13.

[0010] The working method of the power generation system using magnesium as fuel, the power generation system uses magnesium oxide as raw material, when the renewable energy power generation in the power grid system is in excess or surplus, the molten magnesium oxide is electrolyzed by the magnesium oxide electrolysis device 1, and the renewable energy power is converted into the chemical energy of the metal fuel magnesium through the electrochemical reaction for storage; when the renewable energy power generation in the power grid system is insufficient or a certain geographical location in the world needs power supply, the chemical energy of the magnesium fuel is converted into electrical energy through the magnesium combustion and combustion product collection subsystem and the steam Rankine cycle power generation subsystem to realize external power supply; the specific process of converting chemical energy into electrical energy is: the fuel magnesium powder is obtained by the magnesium oxide electrolysis device 1, the fuel magnesium powder and air are reacted with the magnesium powder through the magnesium powder After being mixed in the burner 5, it enters the boiler 6 for combustion, and the combustion reaction equation is 2Mg+O2=2MgO, and the combustion reaction releases a large amount of heat; the newly added power cycle working medium water is mixed with the condensed water recovered by the condenser 13, and then pressurized by the feed water pump 14, and then successively passes through the heat exchanger 8 and the boiler 6 to absorb heat to become high-temperature superheated steam, and then enters the steam turbine 11 to expand and do work and drive the generator 12 to rotate and generate electricity; the product MgO after the combustion of magnesium fuel is separated and collected by the cyclone separator 7 and the dust collector 9, and is stored for standby use. The magnesium oxide can re-enter the magnesium fuel electrolysis preparation subsystem, and is electrolyzed by the magnesium oxide electrolysis device 1 to obtain magnesium fuel again, so as to achieve recycling, and the raw material magnesium oxide is not consumed in the whole process.

[0011] Beneficial effects of the present invention:

[0012] The power generation system using magnesium as fuel and the working method thereof described in the present invention have the following advantages: (1) The energy density of metal fuel magnesium is high; (2) Magnesium fuel does not contain carbon, nitrogen and sulfur elements, and does not produce CO2 and SO2 during combustion. By controlling the combustion temperature and air ratio, the generation of thermal NOx during the combustion process can be effectively controlled; (3) Renewable energy electricity is converted into chemical energy of metal fuel magnesium through electrochemical reaction for storage, which has the advantages of long energy storage period and permanent storage; (4) After the magnesium fuel is burned in the whole process, its combustion product MgO can be regenerated by electrolysis to obtain metal fuel magnesium again. The fuel magnesium is recycled and regenerated without consumption in the whole process; (5) Energy storage through metal fuel magnesium facilitates global energy trade. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 Schematic diagram of the power generation system of the present invention.

[0014] Among them, 1 is a magnesium oxide electrolysis device, 2 is the surplus renewable energy power supply in the power grid, 3 is a cooler, 4 is a magnesium powder storage tank, 5 is a magnesium powder burner, 6 is a boiler, 7 is a cyclone separator, 8 is a heat exchanger, 9 is a dust collector, 10 is a chimney, 11 is a steam turbine, 12 is a generator, 13 is a condenser, and 14 is a feed water pump. DETAILED DESCRIPTION

[0015] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0016] refer to Figure 1 , a power generation system using magnesium as fuel, including a magnesium fuel electrolysis preparation subsystem, a magnesium combustion and combustion product collection subsystem and a steam Rankine cycle power generation subsystem;

[0017] The magnesium fuel electrolysis preparation subsystem includes a magnesium oxide electrolysis device 1, a surplus renewable energy power supply 2 in the power grid, a cooler 3 and a magnesium powder storage tank 4; the electrolyte inlet of the magnesium oxide electrolysis device 1 is connected to the MgO material inlet, the flux inlet of the magnesium oxide electrolysis device 1 is connected to the flux delivery pipeline, the power supply of the magnesium oxide electrolysis device 1 is connected to the surplus renewable energy power supply 2 in the power grid, the cathode of the magnesium oxide electrolysis device 1 is connected to the hot side inlet of the cooler 3, and the hot side outlet of the cooler 3 is connected to the fuel inlet of the magnesium powder storage tank 4;

[0018] The magnesium combustion and combustion product collection subsystem comprises a magnesium powder burner 5, a boiler 6, a cyclone separator 7, a heat exchanger 8, a dust collector 9 and a chimney 10 which are sequentially connected to a magnesium powder storage tank 4 of the magnesium fuel electrolysis preparation subsystem; magnesium powder and air are mixed through the magnesium powder burner 5 and then enter the boiler 6 for combustion, and the combustion reaction equation is 2Mg+O2=2MgO. A large amount of heat is released by the combustion reaction, part of which is absorbed by the working medium in the heating surface around the boiler 6, and the other part of the heat is accompanied by the flue gas through the cyclone separator 7 and then enters the heat exchanger. The flue gas in the flue gas is absorbed by the working medium in the heat exchanger 8, the flue gas outlet of the boiler 6 is connected with the material inlet of the cyclone separator 7, the solid combustion product MgO in the flue gas is separated by the cyclone separator 7 and then collected from the bottom, the gas outlet of the cyclone separator 7 is connected with the hot side inlet of the heat exchanger 8, the hot side outlet of the heat exchanger 8 is connected with the inlet of the dust collector 9, the small amount of fine MgO particles remaining in the flue gas are collected and recycled by the dust collector 9, the flue gas outlet of the dust collector 9 is connected with the inlet of the chimney 10, and the flue gas is finally discharged into the atmosphere through the chimney 10.

[0019] The steam Rankine cycle power generation subsystem includes a steam turbine 11, a generator 12, a condenser 13 and a feed water pump 14; the newly added power cycle working medium water is mixed with the condensed water recovered by condensation in the condenser 13 and connected to the working medium inlet of the feed water pump 14, the working medium outlet of the feed water pump 14 is connected to the cold side inlet of the heat exchanger 8, the cold side outlet of the heat exchanger 8 is connected to the power cycle working medium inlet of the boiler 6, the power cycle working medium outlet of the boiler 6 is connected to the inlet of the steam turbine 11, and the steam The working fluid outlet of the turbine 11 is connected to the working fluid inlet of the condenser 13, and the generator 12 is coaxially connected to the steam turbine 11; the newly added power cycle working fluid water is mixed with the condensate recovered by condensation in the condenser 13 and then enters the feed water pump 14 for pressurization, and then enters the heat exchanger 8 to absorb heat. The working fluid after absorbing heat and heating enters the boiler 6, and continues to absorb heat and heat in the boiler 6 to become high-temperature superheated steam. The high-temperature superheated steam expands and does work in the steam turbine 11 and drives the generator 12 to rotate and generate electricity, and then enters the condenser 13.

[0020] The power generation system using magnesium as fuel described in the present invention uses magnesium oxide as raw material. When the renewable energy power generation in the power grid system is in excess or surplus, the molten magnesium oxide is electrolyzed by the magnesium oxide electrolysis device 1, and the renewable energy power is converted into chemical energy of metal fuel magnesium through electrochemical reaction for storage. When the renewable energy generation in the power grid system is insufficient or a certain geographical location in the world needs electricity supply, the chemical energy of the magnesium fuel is converted into electrical energy through the magnesium combustion and combustion product collection subsystem and the steam Rankine cycle power generation subsystem to realize external power supply; the specific process of converting chemical energy into electrical energy is as follows: the fuel magnesium powder is obtained through the magnesium oxide electrolysis device 1, the fuel magnesium powder and air are mixed through the magnesium powder burner 5 and then enter the boiler 6 for combustion, the combustion reaction equation is 2Mg+O2=2MgO, and the combustion reaction releases a large amount of heat; the newly added power cycle working fluid water is mixed with the condensed water obtained by condensation recovery by the condenser 13, and then the condensed water is boosted by the feed water pump 14, and then successively passes through the heat exchanger 8 and the boiler 6 to absorb heat to become high-temperature superheated steam, and then enters the steam turbine 11 to expand and do work and drive the generator 12 to rotate and generate electricity; the product MgO after the combustion of the magnesium fuel is separated and collected by the cyclone separator 7 and the dust collector 9, and then stored for standby, and the magnesium oxide can re-enter the magnesium fuel electrolysis preparation subsystem, and is electrolyzed by the magnesium oxide electrolysis device 1 to obtain magnesium fuel again, so as to realize recycling, and the raw material magnesium oxide is not consumed in the whole process.

[0021] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A power generation system using magnesium as fuel, characterized in that: It includes a magnesium fuel electrolysis preparation subsystem, a magnesium combustion and combustion product collection subsystem, and a steam Rankine cycle power generation subsystem; The magnesium fuel electrolysis preparation subsystem comprises a magnesium oxide electrolysis device (1), a surplus renewable energy power supply (2) in a power grid, a cooler (3) and a magnesium powder storage tank (4); the electrolyte inlet of the magnesium oxide electrolysis device (1) is connected to the MgO material inlet, the flux inlet of the magnesium oxide electrolysis device (1) is connected to the flux delivery pipeline, the power supply of the magnesium oxide electrolysis device (1) is connected to the surplus renewable energy power supply (2) in the power grid, the cathode of the magnesium oxide electrolysis device (1) is connected to the hot side inlet of the cooler (3), and the hot side outlet of the cooler (3) is connected to the fuel inlet of the magnesium powder storage tank (4); The magnesium combustion and combustion product collection subsystem comprises a magnesium powder burner (5), a boiler (6), a cyclone separator (7), a heat exchanger (8), a dust collector (9) and a chimney (10) which are sequentially connected to the magnesium powder storage tank (4) of the magnesium fuel electrolysis preparation subsystem; magnesium powder and air are mixed through the magnesium powder burner (5) and then enter the boiler (6) for combustion; a large amount of heat is released by the combustion reaction, a part of which is absorbed by the working medium in the heating surface around the boiler (6), and another part of the heat is absorbed by the working medium after entering the heat exchanger (8) along with the flue gas through the cyclone separator (7). The flue gas outlet of the boiler (6) is connected to the material inlet of the cyclone separator (7), the solid combustion product MgO in the flue gas is separated by the cyclone separator (7) and then collected from the bottom, the gas outlet of the cyclone separator (7) is connected to the hot side inlet of the heat exchanger (8), the hot side outlet of the heat exchanger (8) is connected to the inlet of the dust collector (9), the flue gas outlet of the dust collector (9) is connected to the inlet of the chimney (10), the small amount of fine MgO particles remaining in the flue gas are collected and recycled by the dust collector (9), and the flue gas is finally discharged into the atmosphere through the chimney (10); The steam Rankine cycle power generation subsystem comprises a steam turbine (11), a generator (12), a condenser (13) and a feed water pump (14); the newly added power cycle working medium water is mixed with the condensate recovered by condensation in the condenser (13) and then connected to the working medium inlet of the feed water pump (14); the working medium outlet of the feed water pump (14) is connected to the cold side inlet of the heat exchanger (8); the cold side outlet of the heat exchanger (8) is connected to the power cycle working medium inlet of the boiler (6); the power cycle working medium outlet of the boiler (6) is connected to the inlet of the steam turbine (11); The working medium outlet of the turbine (11) is connected to the working medium inlet of the condenser (13), and the generator (12) is coaxially connected to the steam turbine (11); the newly added power cycle working medium water is mixed with the condensate recovered by condensation in the condenser (13) and then enters the feed water pump (14) for pressure increase and then enters the heat exchanger (8) for heat absorption. The working medium after heat absorption and temperature increase enters the boiler (6), and continues to absorb heat and temperature increase in the boiler (6) to become high-temperature superheated steam. The high-temperature superheated steam expands in the steam turbine (11) to do work and drives the generator (12) to rotate and generate electricity and then enters the condenser (13); The flux in the magnesium oxide electrolysis device (1) is a eutectic mixture of MgF2 and CaF2.

2. A power generation system using magnesium as fuel according to claim 1, characterized in that: The surplus renewable energy power supply (2) in the power grid is electricity generated by renewable energy that is difficult to be used in the power grid.

3. The operating method of the power generation system using magnesium as fuel according to claim 1 or 2, characterized in that: The power generation system uses magnesium oxide as a raw material. When the renewable energy power generation in the power grid system is in excess or surplus, the molten magnesium oxide is electrolyzed by the magnesium oxide electrolysis device (1), and the renewable energy power is converted into chemical energy of metal fuel magnesium through an electrochemical reaction for storage; when the renewable energy power generation in the power grid system is insufficient or a certain geographical location in the world needs power supply, the magnesium combustion and combustion product collection subsystem and the steam Rankine cycle power generation subsystem are used to convert the chemical energy of the magnesium fuel into electrical energy to realize external power supply; the specific process of converting chemical energy into electrical energy is: the fuel magnesium powder is obtained by the magnesium oxide electrolysis device (1), the fuel magnesium powder and air are mixed through the magnesium powder burner (5) and then enter the boiler (6) for combustion The combustion reaction equation is 2Mg+O2=2MgO, and a large amount of heat is released by the combustion reaction; the newly added power cycle working medium water is mixed with the condensate recovered by the condenser (13), and then pressurized by the feed water pump (14), and then successively passes through the heat exchanger (8) and the boiler (6) to absorb heat to become high-temperature superheated steam, and then enters the steam turbine (11) to expand and do work and drive the generator (12) to rotate and generate electricity; the product MgO after the magnesium fuel is burned is separated and collected by the cyclone separator (7) and the dust collector (9), and then stored for standby use, and the magnesium oxide re-enters the magnesium fuel electrolysis preparation subsystem, and is electrolyzed by the magnesium oxide electrolysis device (1) to obtain magnesium fuel again, thereby realizing recycling, and the raw material magnesium oxide is not consumed in the whole process.

Images