A high-temperature denitration device using steam and carbon

Abstract

The application discloses a kind of carbon high temperature denitration device, including burner, smelting furnace, biological carbon generation system, combustion-supporting air heating system, reduction chamber, flue gas waste heat utilization system and air induction system;The burner is installed in smelting furnace;The biological carbon generation system includes a shell, the shell and smelting furnace are communicated;The combustion-supporting air heating system includes air blower, air preheater;Combustion-supporting air provided by air blower is first passed through air preheater, absorbs the heat of flue gas in air preheater, then is sent to the burner again;The air induction system includes air induction machine, to be discharged after the flue gas in reduction chamber is introduced into dust removal system, another part is introduced into burner by circulating pipeline.The present denitration device does not affect the combustion and heating process of original furnace, does not need to consume additional energy, and can utilize the carbonization of renewable energy such as biomass to achieve the removal of NOx, to reduce the emission concentration of nitrogen oxides from the source.

Description

Technical Field

[0001] This invention relates to environmental protection technology, specifically to a high-temperature denitrification device for carbon dioxide. Background Technology

[0002] Flue gas is a byproduct of fuel combustion. It contains dust, nitrogen oxides, sulfur oxides, carbon dioxide, and nitrogen, among other things. Nitrogen oxides, in particular, are a significant pollutant; to protect the atmospheric environment, the concentration of this harmful substance must be ensured to be no higher than national emission standards before flue gas emissions. There are three sources of nitrogen oxides in flue gas: fuel-derived NOx, thermal NOx, and random NOx. For high-temperature furnaces, such as glass furnaces, thermal NOx is the primary source, and its formation rate increases rapidly with increasing flame temperature. Therefore, the formation of thermal NOx is unavoidable in high-temperature furnaces such as glass melting furnaces. Since flue gas typically contains large amounts of nitrogen oxides (NOx), such as NO, direct emission of these NOxes into the atmosphere can lead to highly corrosive acid rain. Therefore, flue gas must undergo denitrification (i.e., denitrification) treatment before emission.

[0003] Currently, there are two main mature flue gas denitrification technologies: Selective Catalytic Reduction (SCR) and Selective Non-Catalytic Reduction (SNCR). The chemical reaction principles of SCR and SNCR are the same: a denitrification agent (urea or ammonia) is brought into contact with the flue gas, causing the agent to selectively reduce NOx in the flue gas to produce nitrogen (N2) and water vapor (H2O). SNCR typically takes place in the combustion zone (800-1250℃) of the boiler furnace. SCR, on the other hand, involves setting up a catalyst bed in the flue gas duct, where a catalytic selective reduction reaction occurs at 280-420℃ in the presence of a catalyst.

[0004] SNCR and SCR each have their own advantages and disadvantages. The advantage of SNCR is that it does not require an expensive catalyst bed, but the disadvantage is that the denitrification effect is relatively poor, and the denitrification rate is generally no more than 40%. The disadvantage of SCR is that it requires the use of an expensive catalyst bed and sufficient space to install the catalyst bed, but the advantage is that the denitrification effect is better than SNCR, and the denitrification rate is generally below 60%.

[0005] This shows that the denitrification rate in flue gas denitrification processes needs to be further improved. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a high-temperature denitrification device for carbon dioxide, so as to reduce the emission concentration of nitrogen oxides by utilizing biomass and other materials at high temperatures from the source.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] A high-temperature denitrification device for gas-fired carbon includes a burner, a furnace, a biochar generation system, a combustion air heating system, a reduction chamber, a flue gas waste heat utilization system, and an induced draft system; wherein...

[0009] The burner is installed in the furnace;

[0010] The biochar generation system includes a shell with a feed inlet in the middle and a discharge valve installed at the bottom of the shell; the shell is connected to a furnace, and the flue gas generated by the furnace flows into the shell; the shell has a refractory layer and a heat insulation layer inside.

[0011] The combustion air heating system includes a blower and an air preheater. The combustion air provided by the blower first passes through the air preheater, where it absorbs heat from the flue gas, and is then transferred to the burner to participate in combustion, recovering the waste heat from the flue gas. This process returns some of the waste heat from the flue gas to the combustion system, thereby improving the thermal efficiency of the system.

[0012] The reduction chamber is connected to the shell of the biochar generation system, including a honeycomb denitrification reduction chamber, in which the flue gas completes the denitrification process;

[0013] During the biochar generation process, combustible volatile gases may participate in combustion in the reduction chamber, consuming some of the oxygen in the flue gas. In the reduction chamber, nitrogen oxides and carbon undergo a reduction reaction to complete the denitrification process. After the biomass is carbonized, it becomes part of the reducing agent and participates in the reduction of nitrogen oxides.

[0014] The flue gas waste heat utilization system is connected to the reduction chamber and is located at the rear of the reduction chamber. Due to the high temperature during the reduction process, the flue gas carries a large amount of heat. The flue gas waste heat utilization system is used to utilize the waste heat of the flue gas in the reduction chamber. The waste heat of the flue gas includes the sensible heat carried by the flue gas when it leaves the furnace, the heat released by the combustion of volatile gases during the biochar generation process, and the heat released by the high-temperature carbon oxidation. Part of the waste heat of the flue gas is carried into the combustion system by the combustion air to participate in combustion, and the other part is absorbed by the cooling water system and converted into hot water or steam for comprehensive utilization.

[0015] The exhaust system includes an exhaust fan, which draws part of the flue gas in the reduction chamber into the dust removal system for discharge, and another part is introduced into the burner through a circulation pipe.

[0016] Furthermore, the burner achieves nitrogen oxide emissions through external flue gas recirculation. "Flue gas furnace" refers to the external circulation of flue gas, meaning the flue gas circulates outside the furnace through pipes before re-entering the furnace.

[0017] Furthermore, a one-way valve is installed in the feed inlet to effectively prevent air from entering the exhaust system; a discharge valve is installed at the bottom of the housing to facilitate material discharge.

[0018] Furthermore, the flue gas waste heat utilization system includes an air preheater and a cooling water heat exchanger. Part of the waste heat is returned to the combustion system, and the other part of the waste heat is recovered by using water as a working fluid, so as to improve the overall energy utilization efficiency of the system.

[0019] Furthermore, the honeycomb denitrification reduction chamber is made of carbon layer in a honeycomb shape with straight channels inside. In the last part of the reduction chamber, not only is the resistance small, but the denitrification effect can also be guaranteed. Before the flue gas enters the reduction chamber, the oxygen in the flue gas is completely removed. In this process, only nitrogen oxides and incandescent carbon undergo a reduction reaction, and heat is released at the same time. This part of the heat is utilized in the subsequent flue gas waste heat system.

[0020] Furthermore, a water atomizer is also installed inside the shell of the biocarbon generation system to regulate the temperature of the flue gas in the flue and the content of hydrogen and carbon monoxide in the flue gas, thereby ensuring a reducing atmosphere in the gas.

[0021] Furthermore, during the melting process of the furnace charge in the furnace, the furnace wall needs to be appropriately cooled, the upper part of the furnace is sealed, a slight positive pressure is maintained inside, and the entry of ambient air into the flue gas system is reduced.

[0022] Furthermore, the combustion air supplied by the blower first passes through an air preheater and is heated to over 500°C.

[0023] Furthermore, the temperature of the flue gas in the reduction chamber is 600℃ to 800℃. After passing through the reduction chamber, the flue gas contains no oxygen or nitrogen oxides, only carbon dioxide, water vapor, and dust.

[0024] Furthermore, in the biochar generation system, oxygen in the flue gas is consumed, while carbon monoxide and hydrogen are generated. In the absence of oxygen, nitrogen oxides in the flue gas are rapidly reduced to nitrogen. The biochar generation system consumes all the oxygen in the flue gas and completes over 95% of the denitrification process.

[0025] Compared with the prior art, the advantages of this invention are as follows:

[0026] This denitrification device does not affect the combustion and heating process of the original furnace, requires no additional energy consumption, and can utilize biomass such as straw and garden waste through preliminary crushing and other renewable energy carbonization to remove NOx. It uses waste to treat waste, reducing nitrogen oxide emissions at the source. It is flexible to install, simple to maintain, and can meet the needs of high-temperature furnaces for reducing nitrogen oxide concentrations. Carbon is a strong reducing agent, especially at high temperatures, where incandescent carbon has even stronger reducing power. For natural gas-fired furnaces, the flue gas contains nitrogen, carbon dioxide, water vapor, nitrogen oxides, and trace amounts of oxygen. Incandescent carbon will first react with oxygen in the high-temperature flue gas to produce CO, and then carbon and CO will react with NO... X A reduction reaction occurs, producing nitrogen gas and CO2. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the composition of the high-temperature denitrification device for carbon dioxide provided in an embodiment of the present invention;

[0028] In the diagram: 1. Burner; 2. Furnace; 3. Reduction chamber; 4. Shell; 41. Feed inlet; 42. Rotary discharge valve; 43. Check valve; 5. Blower; 6. Air preheater; 7. Heat exchanger; 8. Exhaust fan. Detailed Implementation

[0029] Example:

[0030] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0031] See Figure 1 As shown, the high-temperature denitrification device for gas carbon provided in this embodiment mainly includes a burner 1, a furnace 2, a biocarbon generation system, a combustion air heating system, a reduction chamber 3, a flue gas waste heat utilization system, and an induced draft system.

[0032] The burner 1 is installed in the furnace 2 and serves as the heating device for the high-temperature furnace. During the process, the combustion air is heated to over 500°C, and the required temperature of the furnace 2's interior is determined according to specific heating process requirements. For example, in a glass furnace, the temperature needs to be above 1600°C. Therefore, the flame temperature is high, resulting in a large amount of thermal nitrogen oxides generated. Thus, in this embodiment, a low-NOx burner is used for burner 1 to minimize the generation of nitrogen oxides.

[0033] Furnace 2 is a crucial part of the production process. Heat is provided by burner 1, creating a high-temperature environment where the charge melts and the reaction process is completed. The walls of furnace 2 require appropriate cooling to ensure their strength. The upper part of the furnace must be sealed and kept under a slight positive pressure to prevent ambient air from entering the flue gas, keeping the oxygen content in the flue gas as low as possible. Simultaneously, the furnace hood also needs proper cooling protection to ensure its mechanical strength, and exhaust vents are provided on the hood.

[0034] The biochar generation system includes a shell 4 with an internal heat-resistant and insulation layer. An inlet 41 is located within the shell 4, and a rotary discharge valve 42 is installed at the bottom. The shell 4 is connected to a furnace 2, allowing the high-temperature flue gas generated by the furnace 2 to flow into the shell 4. This process consumes oxygen in the flue gas and carbonizes the biomass raw materials, generating a reducing agent. The raw material is appropriately crushed biomass blocks or pellets, which enter through the inlet 41 and undergo a series of reaction processes, including drying and carbonization. Feeding is intermittent, only occurring when the biochar generation system is low on material. Normally, the one-way valve is closed to prevent air from entering. The biochar generation system consumes trace amounts of oxygen in the flue gas and generates carbon monoxide and hydrogen. Under oxygen-free conditions and at a set temperature, nitrogen oxides in the flue gas are rapidly reduced to nitrogen. The biochar generation system consumes all the oxygen in the flue gas and achieves 95% denitrification.

[0035] The combustion air heating system includes a blower 5, an air preheater 6, pipes, and valves. The combustion air supplied by the blower 5 first passes through the air preheater 6, where it absorbs heat from the high-temperature flue gas, reaching a temperature above 500°C before entering the burner 1 for combustion. This process recovers some of the waste heat from the flue gas, improving the system's energy efficiency. Due to the high temperature of the combustion air, the pipes and valves downstream of the air preheater 6 must be designed with high-temperature application scenarios in mind, and proper insulation is essential. Because of the high temperature and low density of the combustion air, the air pipes and burner require specialized design to ensure combustion power, with consideration given to reducing nitrogen oxide generation during the design process.

[0036] The reduction chamber consists of three parts: a honeycomb denitrification reduction chamber, where the flue gas completes the denitrification process. During the biochar generation process, combustible volatile gases may participate in combustion within the reduction chamber, consuming some of the oxygen in the flue gas. Within the reduction chamber, nitrogen oxides and carbon undergo a reduction reaction, completing the denitrification process. After denitrification, the flue gas contains no oxygen or nitrogen oxides, only carbon dioxide, water vapor, and trace amounts of dust, with a temperature between 600℃ and 800℃. The flue gas waste heat recovery system is connected to the reduction chamber and located at the rear of the reduction chamber. Due to the high temperature during the reduction process, the flue gas carries a large amount of heat. The flue gas waste heat recovery system is used to utilize the waste heat of the flue gas in the reduction chamber. Part of the waste heat is carried into the combustion system by the combustion air to participate in combustion, and the other part is absorbed by the cooling water system and converted into hot water or steam for comprehensive utilization. The waste heat of the flue gas includes the sensible heat carried by the flue gas when it leaves the furnace, the heat released by the combustion of volatile gases during the biochar generation process, and the heat released by the high-temperature carbon oxidation. After passing through the reduction chamber, the flue gas contains no oxygen or nitrogen oxides, only carbon dioxide, water vapor, and trace amounts of dust. The temperature of the flue gas is between 600°C and 800°C. In this embodiment, the flue gas waste heat recovery system is a heat exchanger 7, which includes a cooling water heat exchanger. Part of the waste heat is returned to the combustion system, and the other part of the waste heat is recovered by using water as the working fluid.

[0037] This allows for the effective use of waste heat from flue gas to generate steam, which can then be used for power generation or refrigeration, converting and utilizing energy according to the energy needs of the production site.

[0038] The induced draft system includes an induced draft fan 8, pipes, and valves. The induced draft fan 8 draws a portion of the flue gas from the reduction chamber 3 into the dust removal system for discharge, while the remaining portion flows through a recirculation pipe into the burner 1 to reduce the generation of nitrogen oxides during combustion. The induced draft fan is the power source for the exhaust system, completing the task of flue gas diversion. Thus, by recirculating a portion of the flue gas after denitrification and deaeration via the induced draft fan 8, some waste heat can be recovered, and the flame can be diluted. In other words, while ensuring the furnace temperature meets requirements, the flame volume is increased, reducing the generation of thermal nitrogen oxides.

[0039] Therefore, this denitrification device does not affect the combustion and heating process of the original furnace, requires no additional energy consumption, and can utilize the preliminary crushing of garden waste and the carbonization of renewable energy sources such as biomass to achieve NOx removal, reducing nitrogen oxide emission concentrations at the source. It is flexible in installation, simple to maintain, and can meet the needs of high-temperature furnaces for reducing nitrogen oxide concentrations. Carbon is a strong reducing agent, especially at high temperatures, where incandescent carbon has even stronger reducing power. For furnaces using natural gas as fuel, the flue gas contains nitrogen, carbon dioxide, water vapor, nitrogen oxides, and trace amounts of oxygen. Incandescent carbon will first react with oxygen in the high-temperature flue gas to produce CO, and then carbon and CO will react with NO...X A reduction reaction occurs, producing nitrogen gas and CO2.

[0040] Preferably, the aforementioned honeycomb denitrification reduction chamber is made of carbon layers in a honeycomb shape with straight channels inside. This design minimizes resistance and provides catalytic and porous media oxidation effects, ensuring a stable reduction process. By controlling the temperature and water vapor volume during the process, the generation of carbon monoxide and hydrogen can be controlled, guaranteeing a high-temperature reducing atmosphere and maximizing NOx reduction. Before the high-temperature flue gas enters the reduction chamber, oxygen is completely removed. During this process, only high-temperature nitrogen oxides react with incandescent carbon, releasing heat. This heat is utilized in the subsequent flue gas waste heat system. The high-temperature flue gas waste heat is recovered by heating combustion air and by setting up a dedicated flue gas waste heat utilization system. In the high-temperature flue gas, carbon dioxide can generate CO and hydrogen. Under the action of high-temperature carbon, CO, and hydrogen, NOx in the flue gas can be efficiently reduced at a certain temperature. For high-temperature kilns, such as glass kilns, the operating temperature is above 1600℃, resulting in the generation of a large amount of thermal NOx. For high-temperature flue gas from glass furnaces and other kilns with an oxygen content of less than 3%, the temperature is above 1300℃. For flue gas from high-temperature kilns such as glass furnaces that use natural gas as fuel, the main components are nitrogen, carbon dioxide, water vapor, nitrogen oxides, and trace amounts of dust. When high-temperature flue gas containing water vapor, nitrogen oxides, and trace amounts of oxygen passes through a carbon layer, it generates carbon monoxide and hydrogen, which are reducing gases. At high temperatures, carbon, carbon monoxide, and hydrogen react with nitrogen oxides to produce nitrogen, carbon dioxide, and water, thereby reducing the emission concentration of nitrogen oxides at the source.

[0041] Preferably, the biocarbon generation system is also equipped with a water atomizer 9. The water atomizer 9 has a water spraying function, which can adjust the temperature of the flue gas in the flue and the content of hydrogen and carbon monoxide in the flue gas, ensuring a reducing atmosphere in the gas, thereby controlling the amount of carbon monoxide and hydrogen generated during the reaction process, ensuring that the process is in a high-temperature reducing atmosphere, so that NOx is reduced to the maximum extent.

[0042] Preferably, a one-way valve 43 is also provided at the feed inlet 41 of the biochar generation system. By providing the one-way valve 43, only raw materials can be fed in, which can effectively prevent the infiltration of air from the environment during the production process, thereby improving the denitrification efficiency of the system and facilitating the consumption of trace amounts of oxygen in the flue gas.

[0043] The above embodiments are merely illustrative of the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made based on the essence of the content of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A high-temperature denitrification device for carbon dioxide, characterized in that, This includes a burner, furnace, biochar generation system, combustion air heating system, reduction chamber, flue gas waste heat utilization system, and induced draft system; among which, The burner is installed in the furnace; The biochar generation system includes a shell with a feed inlet in the shell; the shell is connected to a furnace, and the flue gas generated by the furnace flows into the shell; the shell has a heat-resistant layer and an insulation layer inside. The combustion air heating system includes a blower and an air preheater. The combustion air provided by the blower first passes through the air preheater, where it absorbs heat from the flue gas, and is then transferred to the burner to participate in combustion and recover waste heat from the flue gas. The reduction chamber is connected to the shell of the biochar generation system, including a honeycomb denitrification reduction chamber, in which the flue gas completes the denitrification process; The flue gas waste heat utilization system is connected to the reduction chamber to utilize the waste heat of the flue gas inside the reduction chamber; the waste heat of the flue gas includes the sensible heat carried by the flue gas when it leaves the furnace, as well as the heat released by the combustion of volatile gases and the heat released by carbon oxidation during the biochar generation process. The exhaust system includes an exhaust fan, which draws part of the flue gas in the reduction chamber into the dust removal system for discharge, and another part is introduced into the burner through a circulation pipe; The flue gas waste heat utilization system includes an air preheater and a cooling water heat exchanger. Part of the waste heat is returned to the combustion system, and the other part of the waste heat is recovered by using water as a working fluid. A water atomizer is also installed inside the shell of the biocarbon generation system. This atomizer regulates the temperature of the flue gas in the flue and the content of hydrogen and carbon monoxide in the flue gas, ensuring a reducing atmosphere in the gas.

2. The high-temperature denitrification device for steam carbon as described in claim 1, characterized in that, A one-way valve is installed in the feed inlet, and a discharge valve is installed at the bottom of the housing.

3. The high-temperature denitrification device for steam carbon as described in claim 1, characterized in that, The honeycomb denitrification reduction chamber is made of carbon layers in a honeycomb shape, with straight channels inside. Before the flue gas enters the reduction chamber, the oxygen in the flue gas is completely removed. During this process, only nitrogen oxides react with the hot carbon to undergo a reduction reaction, releasing heat. This heat is then utilized in the subsequent flue gas waste heat system.

4. The high-temperature denitrification device for steam carbon as described in claim 1, characterized in that, During the melting process of the furnace charge in the furnace, the furnace wall needs to be properly cooled, the upper part of the furnace is sealed, and the upper part of the sealed furnace is under positive pressure.

5. The high-temperature denitrification device for steam carbon as described in claim 1, characterized in that, The combustion air supplied by the blower first passes through an air preheater and is heated to over 500°C.

6. The high-temperature denitrification device for steam carbon as described in claim 1, characterized in that, The temperature of the flue gas in the reduction chamber is 600℃ to 800℃. After passing through the reduction chamber, the flue gas contains no oxygen or nitrogen oxides, only carbon dioxide, water vapor and dust.

7. The high-temperature denitrification device for carbon dioxide as described in claim 1, characterized in that, In the biochar generation system, oxygen in the flue gas is consumed, while carbon monoxide and hydrogen are generated. Under the condition of no oxygen in the flue gas and at a set temperature, nitrogen oxides in the flue gas will be rapidly reduced to nitrogen. In the biochar generation system, oxygen in the flue gas is consumed and more than 95% of the denitrification task is completed.

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