A polygeneration system based on silicon fuel and its working method

Abstract

The present invention discloses a silicon fuel-based polygeneration system and a working method thereof, wherein the system comprises a silicon fuel preparation subsystem, a silicon combustion power generation subsystem and a silicon nitride ammonia production subsystem; the present invention effectively couples silicon fuel-based energy storage, silicon combustion power generation, renewable energy water electrolysis and silicon nitride ammonia production, and has the advantages of high energy storage density, long energy storage cycle, permanent storage, fuel cycle regeneration, ammonia-oxygen-electricity polygeneration and convenience for global energy trade.

Description

Technical Field

[0001] The present invention belongs to the technical field of green power generation and advanced energy storage, and in particular relates to a polygeneration system based on silicon 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 to provide a silicon fuel-based polygeneration system and a working method thereof. The system effectively couples silicon fuel energy storage, silicon combustion power generation, renewable energy water electrolysis and silicon nitride ammonia production, and has the advantages of high energy storage density, long energy storage cycle to achieve permanent storage, fuel cycle regeneration, realization of ammonia-oxygen-electricity polygeneration and convenience for global energy trade.

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

[0006] A silicon fuel-based polygeneration system, comprising a silicon fuel preparation subsystem, a silicon combustion power generation subsystem and a silicon nitride ammonia production subsystem;

[0007] The silicon fuel preparation subsystem comprises a powder making device 1, a silicon dioxide / hydrofluoric acid reaction device 2, a SiF4 / H2 reaction device 3, a water electrolysis device 4 and a surplus renewable energy power supply 5 in the power grid; the silicon dioxide ore is connected to the material inlet of the powder making device 1 through a conveying pipeline, the outlet of the powder making device 1 is connected to the silicon dioxide inlet of the silicon dioxide / hydrofluoric acid reaction device 2, the hydrofluoric acid is connected to the hydrofluoric acid inlet of the silicon dioxide / hydrofluoric acid reaction device 2 through a conveying pipeline, in the silicon dioxide / hydrofluoric acid reaction device 2, silicon dioxide reacts with hydrofluoric acid, the reaction equation is SiO2+4HF=SiF4+2H2O, the generated SiF4 gas is passed through the outlet of the silicon dioxide / hydrofluoric acid reaction device 2 and the SiF4 / H2 reaction device 3 is connected to the silicon dioxide inlet of the silicon dioxide / hydrofluoric acid reaction device 2, and the hydrofluoric acid is passed through the outlet of the silicon dioxide / hydrofluoric acid reaction device 2 and the SiF4 / H2 reaction device 3 is connected to the hydrofluoric acid inlet of the silicon dioxide / hydrofluoric acid reaction device 2. The power supply of the water electrolysis device 4 is connected to the surplus renewable energy power supply 5 in the power grid. In the water electrolysis device 4, water undergoes an electrolysis reaction to generate hydrogen (H2) on the cathode and oxygen (O2) on the anode. The hydrogen is connected to the hydrogen inlet of the SiF4 / H2 reaction device 3, and the oxygen is collected for other purposes. In the SiF4 / H2 reaction device 3, SiF4 and H2 react under microwave induced plasma discharge conditions, and the reaction equation is SiF4+H2=Si+HF, generating solid silicon powder and HF gas. The HF gas dissolves in water to form hydrofluoric acid, and the hydrofluoric acid re-enters the silicon dioxide / hydrofluoric acid reaction device 2 to achieve recycling. The generated silicon powder is connected to the fuel inlet of the silicon-fired boiler 6.

[0008] The silicon combustion and power generation subsystem includes a silicon-fired boiler 6, a centrifugal separation device 7, a water supply pump 8, a steam turbine 9, a generator 10 and a condenser 11; air is connected to the oxidant inlet of the silicon-fired boiler 6 through a conveying pipeline, and in the silicon-fired boiler 6, silicon powder and air undergo a combustion reaction, and the reaction equation is Si+O2=SiO2, 3Si+2N2=Si3N4, a large amount of heat is released during the reaction process, and the generated solid product is a mixture of SiO2 and Si3N4, the solid product outlet of the silicon-fired boiler 6 is connected to the material inlet of the centrifugal separation device 7, and the solid product in the centrifugal separation device 7 is centrifuged to form SiO2 and Si3N4 respectively, and SiO2 re-enters the powder making device 1 to achieve recycling, and the generated Si3N4 is mixed with nitrogen The inlet of the ball mill 12 in the silicon-ammonia production subsystem is connected; the working fluid inlet of the silicon-fired boiler 6 is connected to the outlet of the feed water pump 8, the working fluid outlet of the silicon-fired boiler 6 is connected to the inlet of the steam turbine 9, the steam turbine 9 is coaxially connected to the generator 10, the working fluid outlet of the steam turbine 9 is connected to the working fluid inlet of the condenser 11, and the working fluid outlet of the condenser 11 is connected to the working fluid inlet of the feed water pump 8; the working fluid enters the silicon-fired boiler 6 after being pressurized by the feed water pump 8 to absorb the heat generated by the combustion reaction of the fuel silicon, the working fluid temperature rises to become superheated steam, and then enters the steam turbine 9 to expand and do work, and drives the generator 10 to rotate and generate electricity, and the working fluid that has done work enters the condenser 11 through the outlet of the steam turbine 9, becomes water after condensation, and enters the feed water pump 8 again to enter the next cycle process;

[0009] The silicon nitride ammonia production subsystem includes a ball mill 12, a Si3N4 / H2O reaction device 13 and a renewable energy heat source 14; the solid product Si3N4 of silicon powder combustion is connected to the inlet of the ball mill 12, and the silicon nitride powder obtained by grinding is connected to the silicon nitride inlet of the Si3N4 / H2O reaction device 13 through the outlet of the ball mill 12, and water is connected to the water inlet of the Si3N4 / H2O reaction device 13 through a pipeline. In the Si3N4 / H2O reaction device 13, the silicon nitride powder reacts with water at high temperature, and the reaction equation is Si3N4+6H2O=3SiO2+4NH3. The high temperature conditions required for the reaction are provided by the renewable energy heat source 14, and the reaction products are ammonia and SiO2, respectively. Ammonia is an important chemical raw material with huge industrial value, and the generated SiO2 is collected and re-enters the powder production device 1 to achieve recycling.

[0010] The working method of the polygeneration system based on silicon fuel is as follows: the silicon fuel preparation subsystem uses silicon dioxide as raw material. When the renewable energy power generation in the power grid system is in excess or surplus, the hydrogen generated by the water electrolysis device 4 reacts with the SiF4 gas generated by the silicon dioxide / hydrofluoric acid reaction device 2 in the SiF4 / H2 reaction device 3 through microwave induced plasma discharge to generate solid silicon powder, thereby realizing the conversion of renewable energy power into chemical energy of silicon fuel through 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 electricity supply, the chemical energy of silicon fuel is converted into electrical energy through the silicon combustion power generation subsystem to realize external power supply; the specific process of converting the chemical energy of silicon fuel into electrical energy is as follows: silicon powder and air undergo a violent combustion reaction in the silicon-fired boiler 6, and the reaction equations are Si+O2=SiO2, 3Si+2N2=Si3N4, a large amount of heat is released during the reaction, and the working medium enters the silicon-fired boiler 6 after being pressurized by the feed water pump 8 to absorb the fuel silicon combustion reaction The heat generated produces superheated steam, which then enters the steam turbine 9 to expand and do work, and drives the generator 10 to rotate and generate electricity. The working fluid that has done work enters the condenser 11 through the outlet of the steam turbine 9, and becomes water after condensation and enters the water supply pump 8 again to enter the next cycle process; the solid product produced by the combustion of silicon powder is a mixture of SiO2 and Si3N4. In the centrifugal separation device 7, the solid product is centrifuged to form SiO2 and Si3N4 respectively. SiO2 re-enters the powder making device 1 to achieve recycling. The generated Si3N4 enters the ball mill 12 and is ground to obtain silicon nitride powder. In the Si3N4 / H2O reaction device 13, the silicon nitride powder reacts with water at high temperature. The reaction equation is Si3N4+6H2O=3SiO2+4NH3. The high temperature conditions required for the reaction are provided by the renewable energy heat source 14. The reaction products are ammonia and SiO2 respectively. Ammonia is an important chemical raw material with huge industrial value. The generated SiO2 is collected and re-enters the powder making device 1 to achieve recycling.

[0011] Beneficial effects of the present invention:

[0012] The polygeneration system based on silicon fuel and the working method thereof described in the present invention have the following advantages: (1) the energy density of silicon fuel is high; (2) silicon fuel does not contain carbon, and the whole working process of the system does not generate pollutants, which is a green and low-carbon power generation technology; (3) renewable energy electricity is converted into chemical energy of metal fuel silicon through electrochemical reaction for storage, which has the advantages of long energy storage period and permanent storage; (4) after the silicon fuel combustion reaction in the whole process, its combustion products can be recycled to obtain fuel silicon again, and the fuel silicon is recycled and regenerated in the whole process without consumption; (5) ammonia and oxygen can be produced synergistically; (6) energy storage through metal fuel silicon facilitates global energy trade. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the system composition of the present invention.

[0014] Among them, 1 is a powder making device, 2 is a silicon dioxide / hydrofluoric acid reaction device, 3 is a SiF4 / H2 reaction device, 4 is a water electrolysis device, 5 is the surplus renewable energy power supply in the power grid, 6 is a silicon-fired boiler, 7 is a centrifugal separation device, 8 is a feed water pump, 9 is a steam turbine, 10 is a generator, 11 is a condenser, 12 is a ball mill, 13 is a Si3N4 / H2O reaction device, and 14 is a renewable energy heat source. DETAILED DESCRIPTION

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

[0016] refer to Figure 1 , a silicon fuel-based polygeneration system, including a silicon fuel preparation subsystem, a silicon combustion power generation subsystem and a silicon nitride ammonia production subsystem;

[0017] The silicon fuel preparation subsystem comprises a powder making device 1, a silicon dioxide / hydrofluoric acid reaction device 2, a SiF4 / H2 reaction device 3, a water electrolysis device 4 and a surplus renewable energy power supply 5 in the power grid; the silicon dioxide ore is connected to the material inlet of the powder making device 1 through a conveying pipeline, the outlet of the powder making device 1 is connected to the silicon dioxide inlet of the silicon dioxide / hydrofluoric acid reaction device 2, the hydrofluoric acid is connected to the hydrofluoric acid inlet of the silicon dioxide / hydrofluoric acid reaction device 2 through a conveying pipeline, in the silicon dioxide / hydrofluoric acid reaction device 2, silicon dioxide reacts with hydrofluoric acid, the reaction equation is SiO2+4HF=SiF4+2H2O, the generated SiF4 gas is connected to the SiF4 inlet of the SiF4 / H2 reaction device 3 through the outlet of the silicon dioxide / hydrofluoric acid reaction device 2; the power supply of the water electrolysis device 4 It is connected to the surplus renewable energy power supply 5 in the power grid. The surplus renewable energy power supply 5 in the power grid is the electricity generated by renewable energy that is difficult to use in the power grid, so as to reduce costs. In the water electrolysis device 4, water undergoes an electrolysis reaction to generate hydrogen (H2) on the cathode and oxygen (O2) on the anode. The hydrogen is connected to the hydrogen inlet of the SiF4 / H2 reaction device 3, and the oxygen is collected for other purposes. In the SiF4 / H2 reaction device 3, SiF4 and H2 react under microwave induced plasma discharge conditions, and the reaction equation is SiF4+H2=Si+HF, generating solid silicon powder and HF gas. The HF gas dissolves in water to form hydrofluoric acid, and the hydrofluoric acid re-enters the silicon dioxide / hydrofluoric acid reaction device 2 to achieve recycling. The generated silicon powder is connected to the fuel inlet of the silicon-fired boiler 6.

[0018] The silicon combustion and power generation subsystem includes a silicon-fired boiler 6, a centrifugal separation device 7, a water supply pump 8, a steam turbine 9, a generator 10 and a condenser 11; air is connected to the oxidant inlet of the silicon-fired boiler 6 through a conveying pipeline, and in the silicon-fired boiler 6, silicon powder and air undergo a combustion reaction, and the excess air coefficient of the silicon powder and air combustion in the silicon-fired boiler 6 is in the range of 1.0-2.5 to ensure complete combustion, and the reaction equation is Si+O2=SiO2, 3Si+2N2=Si3N4, and a large amount of heat is released during the reaction process, and the generated solid product is a mixture of SiO2 and Si3N4, and the solid product outlet of the silicon-fired boiler 6 is connected to the material inlet of the centrifugal separation device 7, and the solid product in the centrifugal separation device 7 is centrifuged to form SiO2 and Si3N4 respectively, and SiO2 re-enters the powder making device 1. Realize recycling, the generated Si3N4 is connected to the inlet of the ball mill 12 in the silicon nitride ammonia production subsystem; the working medium inlet of the silicon-fired boiler 6 is connected to the outlet of the feed water pump 8, the working medium outlet of the silicon-fired boiler 6 is connected to the inlet of the steam turbine 9, the steam turbine 9 is coaxially connected to the generator 10, the working medium outlet of the steam turbine 9 is connected to the working medium inlet of the condenser 11, and the working medium outlet of the condenser 11 is connected to the working medium inlet of the feed water pump 8; the working medium enters the silicon-fired boiler 6 after being pressurized by the feed water pump 8 to absorb the heat generated by the combustion reaction of the fuel silicon, the working medium temperature rises to become superheated steam, and then enters the steam turbine 9 to expand and do work, and drives the generator 10 to rotate and generate electricity, the working medium that has done work enters the condenser 11 through the outlet of the steam turbine 9, becomes water after condensation, and enters the feed water pump 8 again to enter the next cycle process.

[0019] The silicon nitride ammonia production subsystem includes a ball mill 12, a Si3N4 / H2O reaction device 13 and a renewable energy heat source 14; the solid product Si3N4 of silicon powder combustion is connected to the inlet of the ball mill 12, and the silicon nitride powder obtained by grinding is connected to the silicon nitride inlet of the Si3N4 / H2O reaction device 13 through the outlet of the ball mill 12, and water is connected to the water inlet of the Si3N4 / H2O reaction device 13 through a pipeline. In the Si3N4 / H2O reaction device 13, the silicon nitride powder reacts with water at high temperature, and the reaction equation is Si3N4+6H2O=3SiO2+4NH3. The high temperature conditions required for the reaction are provided by the renewable energy heat source 14, and the reaction products are ammonia and SiO2, respectively. Ammonia is an important chemical raw material with huge industrial value, and the generated SiO2 is collected and re-enters the powder production device 1 to achieve recycling.

[0020] The present invention provides a working method of a polygeneration system based on silicon fuel, which uses silicon dioxide as a raw material. When renewable energy power generation in a power grid system is in excess or surplus, hydrogen generated by a water electrolysis device 4 reacts with SiF4 gas generated by a silicon dioxide / hydrofluoric acid reaction device 2 in a SiF4 / H2 reaction device 3 through microwave induced plasma discharge to generate solid silicon powder, thereby realizing the conversion of renewable energy power into chemical energy of silicon fuel through electrochemical reaction for storage. When there is insufficient renewable energy generation in the power grid system or electricity is needed in some other geographical location in the world, the chemical energy of silicon fuel is converted into electrical energy through the silicon combustion power generation subsystem to provide external power supply; the specific process of converting chemical energy into electrical energy is as follows: silicon powder and air undergo a violent combustion reaction in the silicon-fired boiler 6, and the reaction equation is Si+O2=SiO2, 3Si+2N2=Si3N4. A large amount of heat is released during the reaction process. The working medium enters the silicon-fired boiler 6 after being pressurized by the feed water pump 8 to absorb the heat generated by the combustion reaction of the fuel silicon, generating superheated steam, and then enters the steam turbine 9 to expand and perform work, and drives the generator 10 to rotate and generate electricity. The working medium that has completed the work enters the condenser 11 through the outlet of the steam turbine 9, becomes water after condensation, and enters the feed water pump 8 again to enter the next cycle Process: The solid product produced by the combustion of silicon powder is a mixture of SiO2 and Si3N4. After centrifugal separation in the solid product of the centrifugal separation device 7, SiO2 and Si3N4 are formed respectively. SiO2 re-enters the powder making device 1 for recycling. The generated Si3N4 enters the ball mill 12 and is ground to obtain silicon nitride powder. In the Si3N4 / H2O reaction device 13, the silicon nitride powder reacts with water at high temperature. The reaction equation is Si3N4+6H2O=3SiO2+4NH3. The high temperature conditions required for the reaction are provided by the renewable energy heat source 14. The reaction products are ammonia and SiO2 respectively. Ammonia is an important chemical raw material with huge industrial value. The generated SiO2 is collected and re-enters the powder making device 1 for recycling.

[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 polygeneration system based on silicon fuel, characterized in that: It includes silicon fuel preparation subsystem, silicon combustion power generation subsystem and silicon nitride ammonia production subsystem; The silicon fuel preparation subsystem comprises a powder making device (1), a silicon dioxide / hydrofluoric acid reaction device (2), a SiF4 / H2 reaction device (3), a water electrolysis device (4) and a surplus renewable energy power supply (5) in the power grid; the silicon dioxide ore is connected to the material inlet of the powder making device (1) through a conveying pipeline, the outlet of the powder making device (1) is connected to the silicon dioxide inlet of the silicon dioxide / hydrofluoric acid reaction device (2), the hydrofluoric acid is connected to the hydrofluoric acid inlet of the silicon dioxide / hydrofluoric acid reaction device (2) through a conveying pipeline, and in the silicon dioxide / hydrofluoric acid reaction device (2), silicon dioxide reacts with hydrofluoric acid, and the reaction equation is SiO2+4HF=SiF4+2H2O, and the generated SiF4 gas is discharged through the outlet of the silicon dioxide / hydrofluoric acid reaction device (2) and SiF4 / H2O / Si ... The SiF4 / H2 reaction device (3) is connected to the SiF4 inlet of the SiF4 / H2 reaction device (3); the power supply of the water electrolysis device (4) is connected to the surplus renewable energy power supply (5) in the power grid. In the water electrolysis device (4), water undergoes an electrolysis reaction to generate hydrogen on the cathode and oxygen on the anode. The hydrogen is connected to the hydrogen inlet of the SiF4 / H2 reaction device (3), and the oxygen is collected for other purposes. In the SiF4 / H2 reaction device (3), SiF4 and H2 react under microwave induced plasma discharge conditions, and the reaction equation is SiF4+H2=Si+HF, generating solid silicon powder and HF gas. The HF gas dissolves in water to form hydrofluoric acid, and the hydrofluoric acid re-enters the silicon dioxide / hydrofluoric acid reaction device (2) to achieve recycling. The generated silicon powder is connected to the fuel inlet of the silicon-fired boiler (6); The silicon combustion and power generation subsystem comprises a silicon combustion boiler (6), a centrifugal separation device (7), a water supply pump (8), a steam turbine (9), a generator (10) and a condenser (11); air is connected to the oxidant inlet of the silicon combustion boiler (6) through a conveying pipeline; in the silicon combustion boiler (6), silicon powder and air undergo a combustion reaction; the reaction equation is Si+O2=SiO2, 3Si+2N2=Si3N4; a large amount of heat is released during the reaction process; the generated solid product is a mixture of SiO2 and Si3N4; the solid product outlet of the silicon combustion boiler (6) is connected to the material inlet of the centrifugal separation device (7); in the centrifugal separation device (7), the solid product is centrifugally separated to form SiO2 and Si3N4 respectively; SiO2 re-enters the powder making device (1) to achieve recycling; the generated Si3N4 is mixed with the silicon nitride ammonia making subsystem The inlet of the silicon-fired boiler (6) is connected to the outlet of the feed water pump (8), the outlet of the silicon-fired boiler (6) is connected to the inlet of the steam turbine (9), the steam turbine (9) and the generator (10) are coaxially connected, the outlet of the steam turbine (9) is connected to the inlet of the condenser (11), and the outlet of the condenser (11) is connected to the inlet of the feed water pump (8); the working medium is pressurized by the feed water pump (8) and enters the silicon-fired boiler (6) to absorb the heat generated by the combustion reaction of the fuel silicon, the temperature of the working medium is increased to become superheated steam, the superheated steam enters the steam turbine (9) to expand and do work, and drives the generator (10) to rotate and generate electricity, the working medium that has done work enters the condenser (11) through the outlet of the steam turbine (9), becomes water after condensation, and enters the feed water pump (8) again to enter the next cycle process; The silicon nitride ammonia production subsystem comprises a ball mill (12), a Si3N4 / H2O reaction device (13) and a renewable energy heat source (14); the solid product Si3N4 produced by the combustion of silicon powder is connected to the inlet of the ball mill (12); the silicon nitride powder obtained by grinding is connected to the silicon nitride inlet of the Si3N4 / H2O reaction device (13) through the outlet of the ball mill (12); water is connected to the water inlet of the Si3N4 / H2O reaction device (13) through a pipeline; in the Si3N4 / H2O reaction device (13), the silicon nitride powder reacts with water at high temperature, and the reaction equation is Si3N4+6H2O=3SiO2+4NH3; the high temperature conditions required for the reaction are provided by the renewable energy heat source (14); the reaction products are ammonia and SiO2, respectively; ammonia is an important chemical raw material with great industrial value; the generated SiO2 is collected and re-enters the powder production device (1) to achieve recycling; The excess air coefficient of the silicon powder and air combustion in the silicon-fired boiler (6) is in the range of 1.0-2.5; The surplus renewable energy power supply (5) in the power grid is electricity generated by renewable energy sources that is difficult to use in the power grid.

2. The working method of the polygeneration system based on silicon fuel according to claim 1, characterized in that: The silicon fuel preparation subsystem uses silicon dioxide as a raw material. When the renewable energy generation in the power grid system is in excess or surplus, the hydrogen generated by the water electrolysis device (4) reacts with the SiF4 gas generated by the silicon dioxide / hydrofluoric acid reaction device (2) in the SiF4 / H2 reaction device (3) through microwave induced plasma discharge to generate solid silicon powder, thereby realizing the conversion of renewable energy power into chemical energy of silicon fuel 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 silicon fuel is converted into electrical energy through the silicon combustion power generation subsystem to realize external power supply; the specific process of converting the chemical energy of silicon fuel into electrical energy is as follows: the silicon powder and air undergo a violent combustion reaction in the silicon-fired boiler (6), and the reaction equation is Si+O2=SiO2, 3Si+2N2=Si3N4. A large amount of heat is released during the reaction process. The working fluid enters the silicon-fired boiler (6) after being pressurized by the feed water pump (8) to absorb the heat generated by the fuel silicon combustion reaction to generate superheated steam. The superheated steam The steam enters the steam turbine (9) to expand and do work, and drives the generator (10) to rotate and generate electricity. The working fluid that has done work enters the condenser (11) through the outlet of the steam turbine (9), and becomes water after condensation and enters the water supply pump (8) again to enter the next cycle process. The solid product generated by the combustion of silicon powder is a mixture of SiO2 and Si3N4. The solid product is centrifugally separated in the centrifugal separation device (7) to form SiO2 and Si3N4 respectively. The SiO2 re-enters the powder making device (1) to achieve recycling, and the generated Si3 N4 enters the ball mill (12) and is ground to obtain silicon nitride powder. In the Si3N4 / H2O reaction device (13), the silicon nitride powder reacts with water at high temperature. The reaction equation is Si3N4+6H2O=3SiO2+4NH3. The high temperature conditions required for the reaction are provided by the renewable energy heat source (14). The reaction products are ammonia and SiO2. Ammonia is an important chemical raw material with huge industrial value. The generated SiO2 is collected and re-enters the powder making device (1) to achieve recycling.

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