A low-temperature flue gas direct denitration preparation, a preparation method and application thereof
The prepared low-temperature flue gas direct denitrification agent utilizes components such as MnO2 and reduced iron powder to reduce the reaction kinetic energy of NO and NH3 at low temperatures, solving the problems of high cost and short lifespan of low-temperature SCR denitrification technology, and achieving efficient and economical low-temperature denitrification effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- 武汉钢铁有限公司
- Filing Date
- 2023-09-25
- Publication Date
- 2026-07-03
Smart Images
Figure BDA0004465569480000051
Abstract
Description
Technical Field
[0001] This invention belongs to the field of materials technology, specifically relating to a low-temperature flue gas direct denitrification agent, its preparation method, and its application. Background Technology
[0002] The NOx emission concentration in coke oven flue gas is mostly between 350 and 1000 mg / m³. 3 Between these limits, the NOx concentration must not exceed 150 mg / m³, which is consistent with the ultra-low emission requirement. 3 The difference is significant. NOx emission concentrations in sintering flue gas are mostly between 200 and 500 mg / m³. 3 Between these limits, the NOx concentration must not exceed 50 mg / m³, which is consistent with the ultra-low emission requirement. 3 The gap is significant. To achieve ultra-low NOx emissions from coke oven and sintering flue gas, most coking plants and sintering flue gas manufacturers employ SCR (Selective Catalytic Reduction) denitrification technology. However, these technologies typically require raising the flue gas temperature to above 180°C. Under a given flue gas space velocity, the denitrification catalyst reacts NOx with ammonia in the flue gas to form N2, thus ensuring that the NOx levels in the flue gas meet the corresponding standards. While this method can reduce NOx emissions, the flue gas temperature is mostly around 140°C. To ensure denitrification efficiency, a heating furnace needs to be added before the denitrification process to raise the flue gas temperature. This method not only consumes a lot of energy but also increases the amount of waste gas and NOx generated by the heating furnace combustion, leading to increased ammonia consumption for denitrification. Therefore, developing low-temperature direct flue gas denitrification technology has always been a hot research topic in the industry.
[0003] Existing low-temperature denitrification technologies mainly focus on three aspects: (1) reducing the denitrification reaction space velocity by increasing the amount of denitrification catalyst, which in turn increases the denitrification reaction time to improve denitrification efficiency. (2) increasing the loading of catalytic active components in the catalyst to improve catalytic efficiency and achieve denitrification efficiency improvement. (3) increasing oxidizing components before the denitrification catalytic reaction to reduce the denitrification reaction energy and achieve low-temperature denitrification. The above technical directions still have some problems, mainly manifested in: (1) reducing the space velocity, the increased use of catalyst directly leads to higher denitrification investment costs, larger land area, increased flue gas resistance, and increased main fan power consumption. (2) increasing the loading of active components in the catalyst directly leads to increased denitrification catalyst costs, loss of active components, easy exceedance of flue gas standards after poisoning, and shorter catalyst lifespan. (3) increasing oxidizing components before denitrification, this technology is prone to introducing new pollutants into the flue gas, which is prone to environmental risks.
[0004] In response to the shortcomings of current low-temperature SCR denitrification technology, there is an urgent need to develop a low-temperature flue gas direct denitrification agent to solve the problems of high cost, short lifespan, and new environmental risks associated with low-temperature SCR denitrification technology. Summary of the Invention
[0005] The purpose of this invention is to solve the above three technical problems and achieve direct denitrification of low-temperature flue gas without increasing costs or introducing new environmental risks.
[0006] To achieve the above objectives, the following technical solution is adopted:
[0007] A low-temperature flue gas direct denitrification agent, the composition of which is as follows by mass percentage:
[0008] MnO2 10-15%; reduced iron powder 20-30%; CeO2 0.5-1%; electrostatic precipitator dust from sintering machine head 40-50%; wood charcoal 1-3%; EDTA 0.5-1%; water glass 4-6%; anionic polyacrylamide 0.5-1%; water 4-6%.
[0009] According to the above scheme, the MnO2 is chemical grade MnO2 mineral powder with a mass fraction of ≥75% and a particle size of ≤0.125mm.
[0010] According to the above scheme, the reduced iron powder is reduced iron powder for powder metallurgy, wherein TFe ≥ 98% and the loose packing density is 2.3~2.5 g / cm³. 3 Particle size ≤ 0.15 mm.
[0011] According to the above scheme, the CeO2 REO ≥ 98%, loss on ignition ≤ 1%, and particle size ≤ 1 mm.
[0012] According to the above scheme, the sintering machine head electrostatic precipitator ash is the sintering machine head electric field dust removal ash, which is ground, sieved, and the sieve residue of 2-5mm is taken, wherein TFe≥48% and the particle size is 2-5mm.
[0013] According to the above scheme, the particle size of the charcoal is 0.5-1mm.
[0014] According to the above scheme, the EDTA particle size is ≤0.1mm.
[0015] The preparation method of the above-mentioned low-temperature flue gas direct denitrification agent includes the following steps:
[0016] (1) MnO2, reduced iron powder, CeO2, electrostatic precipitator dust from sintering machine head, wood charcoal and EDTA are stirred and premixed in a closed container to obtain mixed aggregate;
[0017] (2) Place the mixed aggregate in a tube furnace and heat it at 200-300°C with air and nitrogen space velocities of 300-500 h⁻¹. -1 The main material for the process is obtained by reacting under alternating conditions for 30 minutes.
[0018] (3) Mix the main process materials and some water in a sealed container to obtain the primary material;
[0019] (4) Mix the primary material and water glass in a sealed container to obtain the secondary material;
[0020] (5) The mixture of secondary material, polyacrylamide and remaining water is mixed in a sealed container to obtain tertiary material;
[0021] (6) Press the tertiary material into a honeycomb structure to obtain the primary catalyst material;
[0022] (7) Place the primary material at 40-60℃ for 24 hours and then demold to obtain the catalyst semi-finished product;
[0023] (8) The catalyst semi-finished product is cured at 40-60℃ for 48 hours to obtain the catalyst finished product.
[0024] The application of the aforementioned low-temperature flue gas direct denitrification agent in low-temperature flue gas direct denitrification includes calculating the amount of denitrification agent used, W = Q1 / q, where Q1 is the amount of flue gas that has been denitrified, in m³. 3 / h; q is airspeed, in h. -1 The layout adopts a 3-layer arrangement, with each layer having a layout capacity of W / 3.
[0025] Based on the above scheme, the formulation of the denitrification agent is optimized according to the denitrification efficiency η:
[0026] The denitrification efficiency η is calculated using the formula η = (C1 - 50) / C1, where C1 is the NO at the sintering inlet. x Content, unit mg / m³ 3 ;
[0027] When η≤70%, the amount of ash used in the electrostatic precipitator at the sintering machine head is 45-50%, and the amounts of MnO2 and CeO2 used are 12-13% and 0.7-0.9%, respectively.
[0028] When η≥90%, the amount of ash used in the electrostatic precipitator of the sintering machine head is 35-45%, the amount of MnO2 used is 12-13%, and the amount of CeO2 used is 0.7-0.9%; reduced iron powder is used as a conditioning material.
[0029] Based on the above scheme, the formulation of the denitrification agent is optimized according to the air velocity q:
[0030] When the airspeed q is less than 2500h -1 At that time, the amount of MnO2 used is 10-12%, and the amounts of electrostatic precipitator ash and CeO2 used in the sintering machine head are 40-45% and 0.7-0.9%, respectively;
[0031] When the airspeed q is greater than 3500h -1 When using MnO2, the amount used is 14-15%, the amount of electrostatic precipitator dust and CeO2 used in the sintering machine head is 40-45% and 0.7-0.9% respectively, and reduced iron powder is used as a conditioning material.
[0032] Based on the above scheme, the formulation of the denitrification agent is optimized according to the flue gas denitrification temperature T:
[0033] When the temperature is 160-180℃, the amount of CeO2 used is 0.4-0.6%, and the amounts of electrostatic precipitator dust and MnO2 used in the sintering machine head are 40-45% and 12-13%, respectively.
[0034] When the temperature is 140-160℃, the amount of CeO2 used is 0.9-1.0%, the amount of electrostatic precipitator dust and MnO2 used in the sintering machine head is 40-45% and 12-13% respectively, and reduced iron powder is used as a conditioning material.
[0035] The main principle of this invention is to utilize the difference in valence state structure of the effective component metal oxide (Mn-Fe-Ce) in the low-temperature denitrification agent to reduce the reaction kinetic energy of NO and NH3 under low-temperature conditions, thereby achieving direct denitrification of flue gas at low temperatures. The main reaction formula is as follows: 4NO + 4NH3 + O2 → 4N2 + 6H2O.
[0036] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0037] This invention, through the introduction of sintering die head electrostatic precipitator ash and abundant Fe, Mn, Cu, and Zn into the low-temperature flue gas direct denitrification agent, not only supplements the effective elemental components of the agent, but also effectively improves the final strength of the agent and enhances the adhesion of Fe, Mn, and Ce by incorporating elements such as Ca, Si, Mg, and Al. By effectively adjusting the ratio of MnO2, reduced iron powder, and CeO2 in the low-temperature denitrification agent, the denitrification catalytic efficiency can be optimized. The modification of the main components of the Mn-Fe-Ce-based catalyst by wood charcoal and EDTA under medium-temperature conditions enriches the catalyst's valence structure and improves its catalytic efficiency. The binding effect of water glass and anionic polyacrylamide enhances the early strength of the catalyst, preventing pulverization and low yield. This combination of technologies effectively solves the problems of easy loss and poisoning of active components and short catalyst life in traditional catalysts.
[0038] This invention employs premixing, low-temperature modification, secondary mixing, tertiary mixing, quaternary mixing, molding, demolding, and curing processes to ensure the particle size and technical performance requirements of various raw materials in the low-temperature direct denitrification agent. Through stirring and molding processes, the invention guarantees the uniformity of the finished product's performance, bonding strength, and physical dimensions, preventing pulverization and dust generation during packaging, transportation, and use, and improving the effective utilization rate of the denitrification agent. The components added during the preparation of the denitrification agent in the above technology adhere to the catalyst body and are disposed of in compliance with regulations throughout the catalyst's lifespan, avoiding the introduction of new pollutants into the flue gas and the resulting environmental risks.
[0039] This invention further optimizes the application method of low-temperature denitrification agents. Based on differences in denitrification efficiency, space velocity, and denitrification temperature, it rationally optimizes the effective component ratio of the denitrification catalyst, enabling the appropriate selection and use of different flue gas catalysts and improving the catalyst's applicability and effectiveness. It effectively solves the problems of traditional technologies that increase fan power, denitrification investment, land occupation, and operating costs by increasing catalyst usage. Detailed Implementation
[0040] The following embodiments further illustrate the technical solution of the present invention, but are not intended to limit the scope of protection of the present invention.
[0041] A specific embodiment provides a low-temperature flue gas direct denitrification agent, the composition of which is as follows by mass percentage:
[0042] MnO2 10-15%; reduced iron powder 20-30%; CeO2 0.5-1%; electrostatic precipitator dust from sintering machine head 40-50%; wood charcoal 1-3%; EDTA 0.5-1%; water glass 4-6%; anionic polyacrylamide 5‰-1%; water 4-6%.
[0043] Specifically, the MnO2 is chemical grade MnO2 mineral powder with a mass fraction of ≥75% and a particle size of ≤0.125mm.
[0044] Specifically, the reduced iron powder is reduced iron powder for powder metallurgy, wherein TFe ≥ 98% and loose packing density is 2.3–2.5 g / cm³. 3 Particle size ≤ 0.15 mm.
[0045] Specifically, the CeO2 REO is ≥98%, the loss on ignition is ≤1%, and the particle size is ≤1mm.
[0046] Specifically, the sintering machine head electrostatic precipitator ash is the sintering machine head electric field dust, which is ground, sieved, and sieved to obtain 2-5mm sieve residue, wherein TFe≥48% and particle size is 2-5mm.
[0047] Specifically, the charcoal particle size is 0.5–1 mm.
[0048] Specifically, the EDTA particle size is ≤0.1mm.
[0049] Specifically, the water glass meets the superior grade index of L-350-36 in the national standard GBT4209-2022.
[0050] Specifically, the anionic polyacrylamide meets the first-class product indicators in the national standard GB / T17514-2017.
[0051] The specific implementation also provides a method for preparing the above-mentioned low-temperature flue gas direct denitrification agent, including the following steps:
[0052] (1) MnO2, reduced iron powder, CeO2, electrostatic precipitator dust from sintering machine head, wood charcoal and EDTA are stirred and premixed in a closed container to obtain mixed aggregate;
[0053] (2) Place the mixed aggregate in a tube furnace and heat it at 200-300°C with air and nitrogen space velocities of 300-500 h⁻¹. -1 The main material for the process is obtained by reacting under alternating conditions for 30 minutes.
[0054] (3) Mix the main process materials and some water in a sealed container to obtain the primary material;
[0055] (4) Mix the primary material and water glass in a sealed container to obtain the secondary material;
[0056] (5) The mixture of secondary material, polyacrylamide and remaining water is mixed in a sealed container to obtain tertiary material;
[0057] (6) Press the tertiary material into a honeycomb structure to obtain the primary catalyst material;
[0058] (7) Place the primary material at 40-60℃ for 24 hours and then demold to obtain the catalyst semi-finished product;
[0059] (8) The catalyst semi-finished product is cured at 40-60℃ for 48 hours to obtain the catalyst finished product.
[0060] The specific usage parameters of each component in the specific embodiments are shown in Table 1.
[0061]
[0062] Example 1 in the laboratory 1m 3 Experiments were conducted using a low-temperature denitrification experimental setup with a space velocity q of less than 2500 h⁻¹. -1 At a reaction temperature of 150℃, the denitrification efficiency is 65%, and at 170℃, the denitrification efficiency is 70%.
[0063] Example 2 in the laboratory 1m 3 Experiments were conducted using a low-temperature denitrification experimental setup with a space velocity q of less than 2500 h⁻¹. -1 At a reaction temperature of 150℃, the denitrification efficiency is 85%, and at 170℃, the denitrification efficiency is 90%.
[0064] Example 3: Pilot-scale test at 130m 3 Experiments were conducted using a low-temperature denitrification experimental setup with a space velocity q of less than 2500 h⁻¹. -1 At a reaction temperature of 150℃, the denitrification efficiency is 80%, and at 170℃, the denitrification efficiency is 90%.
[0065] Example 4: Pilot-scale test at 130m 3 Experiments were conducted using a low-temperature denitrification experimental setup with a space velocity q greater than 3500 h⁻¹. -1 At a reaction temperature of 150℃, the denitrification efficiency is 75%, and at 170℃, the denitrification efficiency is 85%.
[0066] Example 5: Pilot-scale test at 130m 3 Experiments were conducted using a low-temperature denitrification experimental setup with a space velocity q of less than 2500 h⁻¹. -1 At 170℃, the denitrification efficiency is 90%.
[0067] Example 6: Pilot-scale test at 130m 3 Experiments were conducted using a low-temperature denitrification experimental setup with a space velocity q greater than 3500 h⁻¹. -1 At a reaction temperature of 150℃, the denitrification efficiency is 85%.
[0068] Example 7 in the laboratory 1m 3 Experiments were conducted using a low-temperature denitrification experimental setup with a space velocity q of less than 2500 h⁻¹. -1 At a reaction temperature of 150℃, the denitrification efficiency is 80%, and at 170℃, the denitrification efficiency is 85%.
[0069] Example 8: Pilot-scale test at 130m 3 Experiments were conducted using a low-temperature denitrification experimental setup with a space velocity q greater than 3500 h⁻¹. -1 At a reaction temperature of 150℃, the denitrification efficiency is 80%, and at 170℃, the denitrification efficiency is 90%.
Claims
1. A low-temperature flue gas direct denitrification agent, characterized in that... The composition, expressed as a percentage by mass, is as follows: MnO2 10~15%; reduced iron powder 20~30%; CeO2 0.5~1%; electrostatic precipitator dust from sintering machine head 40~50%; wood charcoal 1~3%; EDTA 0.5~1%; water glass 4~6%; anionic polyacrylamide 0.5~1%; water 4~6%; The preparation method of the low-temperature flue gas direct denitrification agent includes the following steps: (1) Add MnO2, reduced iron powder, and CeO 2、 The sintering die head electrostatic precipitator ash, wood charcoal, and EDTA are stirred and premixed in a sealed container to obtain mixed aggregate; (2) Place the mixed aggregate in a tube furnace and heat it at 200-300°C with air and nitrogen space velocities of 300-500 h⁻¹. -1 The main material for the process is obtained by reacting under alternating conditions for 30 minutes. (3) Mix the main process material and some water in a sealed container to obtain the primary material; (4) The primary material and water glass are mixed in a sealed container to obtain the secondary material; (5) The mixture of secondary material, polyacrylamide and remaining water is mixed in a sealed container to obtain tertiary material; (6) Press the tertiary material into a honeycomb structure to obtain the primary catalyst material; (7) The primary catalyst material is cured at 40~60℃ for 24 hours and then demolded to obtain the catalyst semi-finished product; (8) The catalyst semi-finished product is cured at 40~60℃ for 48h to obtain the catalyst finished product.
2. The low-temperature flue gas direct denitrification agent as described in claim 1, characterized in that... The MnO2 is chemical grade MnO2 mineral powder with a mass fraction of ≥75% and a particle size of ≤0.125mm.
3. The low-temperature flue gas direct denitrification agent as described in claim 1, characterized in that... The reduced iron powder is a powder metallurgy-grade reduced iron powder, wherein TFe ≥ 98% and loose packing density is 2.3~2.5 g / cm³. 3 Particle size ≤ 0.15 mm.
4. The low-temperature flue gas direct denitrification agent as described in claim 1, characterized in that... The CeO2 has a REO content of ≥98%, a loss on ignition of ≤1%, and a particle size of ≤1mm.
5. The low-temperature flue gas direct denitrification agent as described in claim 1, characterized in that... The sintering machine head electrostatic precipitator ash is the sintering machine head electric field dust, which is ground, sieved, and the sieve residue of 2-5mm is taken, wherein TFe≥48% and the particle size is 2~5mm.
6. The low-temperature flue gas direct denitrification agent as described in claim 1, characterized in that... The charcoal has a particle size of 0.5~1mm.
7. The low-temperature flue gas direct denitrification agent as described in claim 1, characterized in that... The EDTA particle size is ≤0.1mm.
8. The application of the low-temperature flue gas direct denitrification agent according to any one of claims 1-7 in low-temperature flue gas direct denitrification, comprising calculating the amount of denitrification agent used W=Q1 / q, where Q1 is the amount of flue gas that has been denitrified, in m³. 3 / h; q is airspeed, in h. -1 The layout adopts a 3-layer arrangement, with each layer having a layout capacity of W / 3.