Ventilation air methane catalytic oxidation system and method based on coupling of green electricity heat compensation and fused salt heat storage

Abstract

The invention discloses a ventilation air methane catalytic oxidation system and method based on green electricity heat compensation coupling fused salt heat storage. The system comprises a two-stage regenerative heat exchange unit, a catalytic oxidation unit, a heat extraction unit and a green electricity-fused salt heat compensation unit. The two-stage regenerative heat exchange unit comprises a low-temperature conduction oil heat exchanger and a high-temperature molten salt heat exchanger, and the two heat exchangers are arranged in a ventilation air methane pipeline and a flue gas pipeline; the green electricity-fused salt heat compensation unit utilizes a solar cell panel to generate electricity, fused salt in a fused salt heat storage tank is heated through an electric heater, and generated high-temperature fused salt enters a high-temperature fused salt heat exchanger and then primarily heats ventilation air methane entering a ventilation air methane pipeline, so that the ventilation air methane meets the temperature of a catalytic oxidation condition; and heat generated after stable combustion of the ventilation air methane in the catalytic oxidation unit is transferred to the two heat exchangers by the flue gas through the flue gas pipeline on one hand, then the entering ventilation air methane is preheated, and on the other hand, the heat is utilized. The ventilation air methane can be treated at low cost and high efficiency, and the system is stable in operation, safe and reliable.

Description

Technical Field

[0001] The present invention relates to the technical field of ultra-low concentration gas treatment, and in particular to a catalytic oxidation system and method for exhaust air based on green electricity heat supplementation coupled with molten salt heat storage. Background Art

[0002] Coal mine ventilation air is a low-concentration methane mixture emitted during mine ventilation, typically containing 0.1% to 1.0% methane. Because methane has a global warming potential (GWP) 25 times that of CO2, direct emissions can exacerbate climate change. However, traditional thermal combustion technologies for treating low-concentration methane require additional fuel (such as natural gas), resulting in high energy consumption and poor economic efficiency. Direct emission or flaring of this gas wastes energy and pollutes the environment. Safely and reliably treating ventilation air is a pressing technical challenge. Summary of the invention

[0003] The purpose of the present invention is to propose a catalytic oxidation system and method for exhaust air based on green electricity heat supplementation coupled with molten salt heat storage, which can process exhaust air at low cost and high efficiency and realize stable operation of the system.

[0004] To achieve the above object, the technical solution adopted by the present invention is:

[0005] In the first aspect, the present invention proposes a catalytic oxidation system for exhaust air based on green electricity heat supplementation coupled with molten salt heat storage, comprising:

[0006] A two-stage heat recovery heat exchange unit includes a low-temperature thermal oil heat exchanger, a high-temperature molten salt heat exchanger, a ventilation air duct, and a flue gas duct. The low-temperature thermal oil heat exchanger is partially located in the ventilation air duct and partially located in the flue gas duct; the high-temperature molten salt heat exchanger is partially located in the ventilation air duct and partially located in the flue gas duct. The flow direction of the ventilation air entering the ventilation air duct is opposite to the exhaust direction of the flue gas.

[0007] The catalytic oxidation unit, the exhaust air duct and the flue gas duct are connected to the catalytic oxidation unit from the top and bottom respectively;

[0008] a heat extraction unit, disposed in the catalytic oxidation unit, for absorbing heat in the catalytic oxidation unit;

[0009] The green electricity-molten salt heat supplement unit includes a solar panel, an electric heater and a molten salt heat storage tank. The electric heater is located in the molten salt heat storage tank and is used to heat the molten salt. The solar panel is used to power the electric heater, and the molten salt heat storage tank is connected to the high-temperature molten salt heat exchanger.

[0010] As a further improvement of the present invention, the catalytic oxidation unit is a catalytic oxidation chamber, which is divided into an oxidation section, a heat exchange section and a flue section according to the flow direction of the exhausted air. The oxidation section is connected to the exhausted air pipeline and is used for the catalytic oxidation of the exhausted air; the heat exchange section is used for absorbing the heat of catalytic oxidation, and is filled with alumina balls inside. The alumina balls are divided into upper, middle and lower layers. The upper and lower layers have a diameter of 5 mm, and the middle layer has a diameter of 3 mm; the flue section is divided into a honeycomb layer, a fiber felt and a filter layer according to the flue gas flow direction. The honeycomb layer is filled with honeycomb ceramics of 300 cpsi and the surface is loaded with a catalyst. The fiber felt layer is filled with zirconia fiber felt with a diameter of 8 μm, and the filter layer is filled with foam ceramics with variable pore sizes.

[0011] As a further improvement of the present invention, the oxidation section is divided into a rectification layer and an oxidation layer according to the flow direction of the exhausted air. The rectification layer is foam ceramics of 60 ppi and is used for making the air flow distribution uniform and preventing backfire; the oxidation layer is foam ceramics of 40 ppi loaded with a catalyst and is used for the deep oxidation of the exhausted air.

[0012] As a further improvement of the present invention, according to the flue gas flow direction of the filter layer, the pore diameters of the foam ceramics are 2 mm, 1 mm and 0.5 mm in sequence.

[0013] As a further improvement of the present invention, the catalyst adopts a Ni-based porous medium catalyst.

[0014] As a further improvement of the present invention, the surface of the alumina balls is subjected to fluoroalkylsilane hydrophobic modification to enhance the anti-fouling property.

[0015] As a further improvement of the present invention, the green electricity-molten salt heat supplement unit further includes an inverter and an electric control cabinet. The inverter is connected to the solar panel to generate alternating current, and the electric control cabinet is respectively connected to the inverter and the electric heater; the control cabinet is also used for accessing the low-valley electricity at night to supply power to the electric heater.

[0016] In the second aspect, the present invention also proposes a method for catalytic oxidation of exhausted air based on green electricity heat supplement coupled with molten salt heat storage, which adopts the above-mentioned system for catalytic oxidation of exhausted air based on green electricity heat supplement coupled with molten salt heat storage. The method includes the following steps:

[0017] Step S1: When the system is cold-started, the solar panel is used to generate electricity. The generated electric energy acts on the electric heater through the electric control cabinet to heat the molten salt heat storage tank, so that the temperature of the molten salt gradually rises. The molten salt flows into the high-temperature molten salt heat exchanger to preheat the exhausted air entering the catalytic oxidation chamber through the exhausted air pipeline; when the exhausted air is preheated to 450 °C, the catalyst in the oxidation section reacts with methane in the exhausted air for catalytic oxidation reaction, and the electric heater stops heating;

[0018] Step S2: The high-temperature flue gas generated by the catalytic oxidation reaction conducts heat to the high-temperature molten salt heat exchanger and the low-temperature heat-conducting oil heat exchanger in the flue gas pipeline; the low-temperature heat-conducting oil heat exchanger preheats the incoming exhausted air to 250 °C, and then preheats it to 450 °C through the high-temperature molten salt heat exchanger, and then sends it into the catalytic oxidation chamber for catalytic oxidation reaction, and the system enters the self-sustaining operation state;

[0019] Step S3: When the temperature of the generated flue gas > 550 °C, start the heat extraction unit, and send water into the heat exchange tubes buried in the catalytic oxidation chamber through the feed water pump for heat exchange, and output hot water or steam for heating or power generation;

[0020] Step S4: When the temperature of the generated flue gas < 550 °C, turn off the heat extraction unit, and the heat of the high-temperature flue gas is used to heat the heat-conducting oil and molten salt in the flue gas pipeline to maintain the temperature of the working medium in the two-stage regenerative heat exchange unit, so that the temperature of the molten salt in the high-temperature molten salt heat exchanger remains at 500 °C, and the temperature of the heat-conducting oil in the low-temperature heat-conducting oil heat exchanger remains at 300 °C;

[0021] Step S5: When the temperature of the molten salt in the high-temperature molten salt heat exchanger is lower than 500 °C, turn on the electric heater for heating, and pump the high-temperature molten salt in the molten salt heat storage tank into the high-temperature molten salt heat exchanger for supplementary heating.

[0022] As a further improvement of the present invention, in step S4, when the flue gas temperature is less than 100 degrees at the outlet, open the smoke baffle to let the flue gas flow out; otherwise, close the smoke baffle to make it stay in the flue gas channel temporarily, and continue to exchange heat with the low-temperature heat-conducting oil heat exchanger and the high-temperature molten salt heat exchanger.

[0023] As a further improvement of the present invention, in step S5, when the temperature of the molten salt in the high-temperature molten salt heat exchanger is lower than 500 °C, during the day, the electric heater is powered by the solar panel; at night, it is heated by the off-peak electricity.

[0024] Compared with the prior art, the present invention has the following technical advantages:

[0025] (1) When the system is cold-started, the solar panel generates electricity, heats the molten salt in the molten salt heat storage tank through the electric heater, and then heats the exhausted air entering the exhausted air pipeline. When the temperature condition is met, a catalytic oxidation reaction is carried out in the catalytic oxidation chamber, releasing a large amount of heat energy. The generated high-temperature flue gas heats the high-temperature molten salt heat exchanger and the low-temperature heat-conducting oil heat exchanger, and the two heat exchangers preheat and heat the exhausted air in the exhausted air pipeline to achieve countercurrent heat exchange; when the exhausted air reaches a certain temperature, it is sent into the catalytic oxidation chamber for reaction, so as to achieve self-sustaining operation without the supplement of fossil fuels, so as to continuously treat ultra-low-concentration gas (exhausted air), prevent it from flowing into the atmosphere, and achieve low-cost operation;

[0026] (2) The catalytic oxidation chamber of the present invention can effectively improve the oxidation stability and catalytic conversion efficiency, and reduce pollutant emissions; it adopts a gradient functional partition, that is, the catalytic oxidation chamber is divided into an oxidation section, a heat exchange section and a flue gas section. A rectifying layer of 60 ppi foam ceramics is arranged in the oxidation section, which can make the air flow distribution uniform and prevent backfire; an oxidation layer of 40 ppi foam ceramics is arranged to deeply oxidize the exhausted air. The above arrangement structure with variable pore density can effectively improve the stability of oxidation propagation; in the heat exchange section, a filling structure of large diameter, medium diameter and large diameter is adopted according to the air flow direction, which can reduce the inlet pressure drop at the inlet of the heat exchange section of the flue gas, and is beneficial to enhancing turbulence in the middle layer, thereby strengthening heat exchange; the flue is divided into a honeycomb layer, a fiber felt layer and a filter layer. The honeycomb layer is filled with 300 cpsi honeycomb ceramics and the surface is loaded with a catalyst to forcibly form Taylor-Couette flow, generate a high shear rate, break the flue gas boundary layer, and force unoxidized methane molecules to migrate to the catalyst surface to oxidize the residual methane; the fiber felt layer is filled with zirconia fiber felt, and the three-dimensional network structure induces Karman vortex streets, significantly enhancing the gas-solid mass transfer efficiency and reducing CO emissions; the filter layer is filled with foam ceramics with variable pore diameters to intercept dust particles and can achieve self-cleaning;

[0027] (3) When the temperature of the flue gas generated by catalytic oxidation is greater than 550 degrees, the heat extraction unit can heat the heat exchange tubes arranged in the catalytic oxidation chamber to output hot water or steam for industrial production or domestic services;

[0028] (4) When the molten salt of the high-temperature molten salt heat exchanger is lower than 500 degrees, during the day, solar power is used to act on the electric heater to supplement heat to the molten salt, and at night, off-peak electricity is used to act on the electric heater to supplement heat to the molten salt, operating in a green power supply mode, so that the entire catalytic oxidation system operates in a low-cost manner and realizes continuous treatment of the exhausted air. Description of the Drawings

[0029] The present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0030] Figure 1 is the schematic diagram of the principle of the exhausted air catalytic oxidation system based on green power heat supplement coupling molten salt heat storage of the present invention;

[0031] Figure 2 is the internal structure schematic diagram of the catalytic oxidation chamber;

[0032] Figure 3 is the operation process diagram of the exhausted air catalytic oxidation method based on green power heat supplement coupling molten salt heat storage of the present invention. Detailed Embodiments

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present invention fall within the scope of protection of the present invention.

[0034] Please refer to Figure 1 , the waste air catalytic oxidation system based on green electricity supplemented heat coupling molten salt heat storage of the present invention includes a two-stage regenerative heat exchange unit, a catalytic oxidation unit, a heat extraction unit, and a green electricity-molten salt heat supplement unit.

[0035] Specifically, the two-stage regenerative heat exchange unit includes a low-temperature heat transfer oil heat exchanger, a high-temperature molten salt heat exchanger, a waste air pipeline, and a flue gas pipeline. The waste air pipeline and the flue gas pipeline are arranged in parallel. The low-temperature heat transfer oil heat exchanger is divided into two connected parts, one part is located inside the inlet of the waste air pipeline, and the other part is located inside the inlet of the flue gas pipeline. The high-temperature molten salt heat exchanger is also divided into two interconnected parts, one part is located inside the waste air pipeline, and the other part is located inside the flue gas pipeline. The high-temperature molten salt heat exchanger is located on the side of the low-temperature heat transfer oil heat exchanger away from the inlet of the waste air pipeline. The heat transfer oil in the low-temperature heat transfer oil heat exchanger is an alkylbenzene synthetic heat transfer oil, and the molten salt in the high-temperature molten salt heat exchanger is a binary nitrate mixture, that is, 60% NaNO3 and 40% KNO3.

[0036] The catalytic oxidation unit, that is, the catalytic oxidation chamber. The waste air pipeline and the flue gas pipeline are respectively communicated with the catalytic oxidation chamber in the upper and lower parts. Specifically, the waste air pipeline is communicated with the upper part of the catalytic oxidation chamber, and the flue gas pipeline is communicated with the upper part of the catalytic oxidation chamber once. The flow direction of the waste air in the waste air pipeline is opposite to the flow direction of the flue gas in the flue gas pipeline, and the two are in countercurrent operation.

[0037] Please refer to Figure 2 , the catalytic oxidation chamber is a cubic structure, and the longitudinal section structure shown in the figure. The interior of the catalytic oxidation chamber is divided into three functional areas, namely the oxidation section, the heat exchange section, and the flue section.

[0038] The oxidation section is filled with foam ceramics loaded with catalysts, and is divided into a rectifying layer and an oxidation layer along the flow direction of the waste air. The rectifying layer is filled with 60 ppi foam ceramics to make the air flow distribution uniform and prevent backfire. The oxidation layer is 40 ppi foam ceramics loaded with catalysts, and the waste air is deeply oxidized at this stage. The arrangement method with variable pore density in the oxidation section is beneficial to preventing backfire and improving the stability of oxidation propagation.

[0039] The heat exchange section is filled with Al2O3. The diameter of the small balls at the inlet and outlet areas of the small balls is 5 mm, and the diameter of the middle core area is 3 mm. The vibration process is used for filling. The large diameter in the inlet area of the exhausted air is used to reduce the inlet pressure drop, and the smaller diameter of the core area is beneficial to enhancing the turbulence, thereby strengthening the heat exchange. Specifically, the surface of the alumina small balls is plasma sprayed with a Cr2O3-SiO2 composite layer to strengthen the radiative heat exchange. At the same time, the surface is hydrophobically modified with fluorosilane to enhance the anti-fouling property.

[0040] The flue gas section is divided into a honeycomb layer, a fiber felt layer, and a filter layer. The honeycomb layer is filled with honeycomb ceramics with 300 cpsi, and the surface is loaded with a catalyst to forcibly form Taylor-Couette flow, generate a high shear rate, break the flue gas boundary layer, and force the unoxidized methane molecules to migrate to the catalyst surface to oxidize the residual methane; the fiber felt layer is filled with zirconia fiber felt with a diameter of 8 μm, and the three-dimensional network structure induces the von Kármán vortex street, significantly enhancing the gas-solid mass transfer efficiency and reducing CO emissions; the filter layer is filled with foam ceramics with variable pore diameters, and the pore diameters are 2 mm, 1 mm, and 0.5 mm along the flow direction, respectively, for intercepting dust particles and achieving self-cleaning.

[0041] The catalytic oxidation chamber adopts a gradient functional partition, which can stably and fully oxidize the exhausted air in the catalytic oxidation chamber and reduce the pollution of the flue gas discharged.

[0042] The heat extraction unit includes heat exchange tubes, and the heat exchange tubes are located in the heat exchange section of the catalytic oxidation chamber. Specifically, the heat exchange tubes adopt a spiral coil tube or fin tube structure, which can increase the heat exchange area and improve the heat exchange efficiency. The pipe material is selected as 316L stainless steel or copper-nickel alloy with high temperature resistance and corrosion resistance, which can achieve long-term stable operation.

[0043] The green power - molten salt heat supplement unit includes solar panels, an inverter, an electric heater, an electric control cabinet, and a molten salt heat storage tank. The solar panels cooperate with the inverter to generate alternating current, which is supplied to the electric heater through the electric control cabinet. The electric heater is located in the molten salt heat storage tank; the molten salt heat storage tank is connected to a high-temperature molten salt heat exchanger. The control cabinet can access the low-valley electricity at night and perform intelligent switching between solar power generation and low-valley electricity.

[0044] This system is also provided with a controller and a temperature monitoring unit. The controller is connected to the temperature monitoring unit, the two-stage regenerative heat exchange unit, the catalytic oxidation chamber, the heat extraction unit, and the green power - molten salt heat supplement unit. Among them, the temperature monitoring unit is temperature sensors arranged in each unit of the system. For example, preheating temperature sensors and heating temperature sensors are arranged in the exhausted air pipeline, temperature sensors are set at the inlet and outlet of the flue gas pipeline, and flue gas temperature sensors are arranged in the catalytic oxidation chamber. The above sensors form a temperature monitoring network to provide node temperature information for system control.

[0045] Please refer to Figure 3, the present invention also provides a method for catalytic oxidation of exhausted air based on green electricity supplemented heat coupled with molten salt thermal energy storage, comprising the following steps:

[0046] Step S1: When the system is cold-started, exhausted air is introduced into the catalytic oxidation chamber through the exhausted air pipeline. Solar panels are used to generate electricity, and the generated electric energy acts on the electric heater through the electric control cabinet to heat the molten salt heat storage tank, gradually increasing the temperature of the molten salt. The molten salt flows into the high-temperature molten salt heat exchanger to preheat the exhausted air flowing in the exhausted air pipeline. When the exhausted air is preheated to 450 °C, the catalyst in the oxidation section undergoes a catalytic oxidation reaction with methane in the exhausted air, and the electric heater stops heating.

[0047] Step S2: The high-temperature flue gas discharged from the catalytic oxidation chamber conducts heat to the high-temperature molten salt heat exchanger and the low-temperature heat-conducting oil heat exchanger in the flue gas pipeline, and then is discharged; the low-temperature heat-conducting oil heat exchanger preheats the incoming exhausted air to 250 °C, then preheats it to 450 °C through the high-temperature heat exchanger, and then sends it into the catalytic oxidation chamber for catalytic oxidation reaction, and the system enters self-sustaining operation.

[0048] Step S3: When the temperature of the generated flue gas > 550 °C, the heat extraction unit is started, and water is sent into the heat exchange tubes buried in the oxidation chamber through the feed water pump for heat exchange, and hot water or steam is output for heating or power generation.

[0049] Step S4: When the temperature of the generated flue gas < 550 °C, the heat extraction system is closed, and the heat of the flue gas is completely used to heat the molten salt and the heat-conducting oil to maintain the temperature of the working medium in the two-stage regenerator, so that the temperature of the molten salt in the heat exchanger is maintained at 500 °C, and the temperature of the heat-conducting oil is maintained at 300 °C; then it is discharged when it is less than 100 degrees.

[0050] Step S5: When the temperature of the molten salt in the high-temperature molten salt heat exchanger is lower than 500 °C, the electric heater is turned on, and the high-temperature molten salt in the molten salt heat storage tank is pumped into the regenerator for heat supplement. When the temperature of the molten salt in the high-temperature molten salt heat exchanger is lower than 500 °C, during the day, solar panels are used to generate electricity and act on the electric heater, and at night, it is heated by off-peak electricity to reduce the electricity cost.

[0051] In summary, the present invention uses solar energy and off-peak electricity at night to perform a cold start on the system, and continues to supplement heat with solar energy and off-peak electricity at night after the flue gas in the catalytic oxidation chamber of the system is lower than the set temperature, so as to enable the system to operate in a low-cost mode; after the system performs a cold start, the high-temperature flue gas in the flue gas pipeline is used to perform secondary heat supplement on the lean air, so that it reaches the temperature required for catalytic oxidation, and then enters the catalytic oxidation chamber to perform the conversion of chemical energy and release a large amount of heat, thereby realizing the self-sustaining operation of the system and enabling the long-term treatment of lean air; the functional partition design of the catalytic oxidation chamber can achieve stable, efficient and clean operation of lean air catalytic oxidation; the heat extraction unit can utilize the heat released by catalytic oxidation to serve industry and daily life.

[0052] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited thereto. All changes that can be made without departing from the spirit of the present invention within the knowledge of those skilled in the art to which the present invention pertains are within the protection scope of the claims of the present invention.

Claims

1. A waste gas catalytic oxidation system based on green electricity supplemented heat coupling molten salt thermal energy storage, characterized in that, Comprising: A two-stage regenerative heat exchange unit, including a low-temperature heat-conducting oil heat exchanger, a high-temperature molten salt heat exchanger, a waste air duct, and a flue gas duct. The low-temperature heat-conducting oil heat exchanger is partially located in the waste air duct and partially in the flue gas duct; the high-temperature molten salt heat exchanger is partially located in the waste air duct and partially in the flue gas duct; the flow direction of the waste air entering the waste air duct is opposite to the discharge direction of the flue gas. A catalytic oxidation unit, where the waste air duct and the flue gas duct communicate with the catalytic oxidation unit from the upper and lower parts respectively. A heat extraction unit, arranged in the catalytic oxidation unit to absorb the heat in the catalytic oxidation unit. A green electricity - molten salt heat supplement unit, including solar panels, an electric heater, and a molten salt heat storage tank. The electric heater is located in the molten salt heat storage tank and is used to heat the molten salt; the solar panels are used to supply power to the electric heater, and the molten salt heat storage tank is connected to the high-temperature molten salt heat exchanger.

2. The waste air catalytic oxidation system based on green power supplemented heat coupling molten salt thermal energy storage according to claim 1, characterized in that, The catalytic oxidation unit is a catalytic oxidation chamber, which is divided into an oxidation section, a heat exchange section, and a flue section according to the flow direction of the waste air. The oxidation section is connected to the waste air duct and is used for the catalytic oxidation of the waste air; the heat exchange section is used to absorb the heat of catalytic oxidation, and is filled with alumina balls. The alumina balls are divided into upper, middle, and lower layers. The upper and lower layers have a diameter of 5 mm, and the middle layer has a diameter of 3 mm; the flue section is divided into a honeycomb layer, a fiber felt layer, and a filter layer according to the flow direction of the flue gas. The honeycomb layer is filled with honeycomb ceramics with 300 cpsi, and the surface is loaded with a catalyst. The fiber felt layer is filled with zirconia fiber felt with a diameter of 8 μm, and the filter layer is filled with foam ceramics with variable pore sizes.

3. The waste air catalytic oxidation system based on green electricity supplemented heat coupled with molten salt thermal energy storage according to claim 2, wherein, The oxidation section is divided into a rectifying layer and an oxidation layer according to the flow direction of the waste air. The rectifying layer is foam ceramics with 60 ppi, which is used to make the air flow distribution uniform and prevent backfire; the oxidation layer is foam ceramics with 40 ppi loaded with a catalyst, which is used for the deep oxidation of the waste air.

4. The waste gas catalytic oxidation system based on green electricity supplemented heat coupling molten salt thermal energy storage according to claim 3, characterized in that, According to the flow direction of the flue gas in the filter layer, the pore diameters of the foam ceramics are 2 mm, 1 mm, and 0.5 mm in sequence.

5. The spent air catalytic oxidation system based on green electricity supplemented heat coupled with molten salt thermal energy storage according to claim 2, characterized in that, The catalyst uses a Ni-based porous medium catalyst.

6. The spent air catalytic oxidation system based on green power supplemented heat coupling molten salt thermal energy storage according to claim 2, wherein, The surface of the alumina balls is modified with fluorosilane for hydrophobicity to enhance the anti-fouling property.

7. The spent air catalytic oxidation system based on green electricity supplemented heat coupled with molten salt thermal energy storage according to claim 1, characterized in that, The green electricity - molten salt heat supplement unit further includes an inverter and an electric control cabinet. The inverter is connected to the solar panels to generate alternating current, and the electric control cabinet is respectively connected to the inverter and the electric heater; the control cabinet is also used to access the low-valley electricity at night to supply power to the electric heater.

8. A method for catalytic oxidation of waste air based on green electricity heat supplement coupled with molten salt heat storage, using the waste air catalytic oxidation system based on green electricity heat supplement coupled with molten salt heat storage according to any one of claims 1 - 7. The method includes the following steps: Step S1: When the system is cold-started, the solar panels are used to generate electricity. The generated electric energy acts on the electric heater through the electric control cabinet to heat the molten salt heat storage tank, gradually increasing the temperature of the molten salt. The molten salt flows into the high-temperature molten salt heat exchanger to preheat the waste air entering the catalytic oxidation chamber through the waste air duct. When the waste air is preheated to 450 °C, the catalyst in the oxidation section reacts with methane in the waste air for catalytic oxidation, and the electric heater stops heating. Step S2: The high-temperature flue gas generated by the catalytic oxidation reaction conducts heat to the high-temperature molten salt heat exchanger and the low-temperature heat-conducting oil heat exchanger in the flue gas pipeline; the low-temperature heat-conducting oil heat exchanger preheats the incoming exhausted air to 250 °C, and then preheats it to 450 °C through the high-temperature molten salt heat exchanger, and then sends it into the catalytic oxidation chamber for catalytic oxidation reaction, and the system enters the self-sustaining operation state; Step S3: When the temperature of the generated flue gas > 550 °C, start the heat extraction unit, and send water into the heat exchange tubes buried in the catalytic oxidation chamber through a feed pump for heat exchange, and output hot water or steam for heating or power generation; Step S4: When the temperature of the generated flue gas < 550 °C, turn off the heat extraction unit, and the heat of the high-temperature flue gas is used to heat the heat-conducting oil and molten salt in the flue gas pipeline to maintain the temperature of the working medium in the two-stage regenerative heat exchange unit, so that the temperature of the molten salt in the high-temperature molten salt heat exchanger remains at 500 °C, and the temperature of the heat-conducting oil in the low-temperature heat-conducting oil heat exchanger remains at 300 °C; Step S5: When the temperature of the molten salt in the high-temperature molten salt heat exchanger is lower than 500 °C, turn on the electric heater for heating, and pump the high-temperature molten salt in the molten salt heat storage tank into the high-temperature molten salt heat exchanger for supplementary heat.

9. The method for catalytic oxidation of exhausted air based on coupling green power for heat supplement and molten salt heat storage according to claim 8, characterized in that, In step S4, when the flue gas temperature is less than 100 degrees at the outlet, open the smoke baffle to let the flue gas flow out; otherwise, turn off the smoke baffle to make it stay in the flue gas channel temporarily and continue to exchange heat with the low-temperature heat-conducting oil heat exchanger and the high-temperature molten salt heat exchanger.

10. The method for catalytic oxidation of exhausted air based on coupling green electricity for heat supplement and molten salt thermal energy storage according to claim 8, wherein In step S5, when the temperature of the molten salt in the high-temperature molten salt heat exchanger is lower than 500 °C, during the day, the electric heater is powered by the solar panels; at night, it is heated by off-peak electricity.

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