Method for treating oxidizing fumes in the production of foamed nickel

Abstract

The present application belongs to the technical field of flue gas produced by foamed nickel, and discloses a treatment method of oxidation flue gas in foamed nickel production, which can realize efficient utilization of heat energy and inhibition of dioxin source. The temperature of the oxidation flue gas is 500-700℃, and the oxidation flue gas contains O2, acid gas, elemental nickel, nickel oxide, and one or more of VOCs, tar, H2, CO, carbon black and polyurethane pyrolysis melt. The treatment method comprises the following steps: a pretreatment process, in which the oxidation flue gas is collected and heat-insulated, and a first gas with a temperature drop of ≤30℃ is output; an oxidation combustion process, in which the VOCs, tar, H2, CO, carbon black and polyurethane pyrolysis melt in the first gas are oxidized and combusted to be removed, and the elemental nickel is oxidized to nickel oxide, and a second gas is output; a waste heat recovery process, in which the second gas is heat-exchanged to obtain a third gas; and a post-treatment process, in which the third gas is dedusted and deacidified to obtain clean tail gas.

Description

Technical Field

[0001] This invention relates to the technical field of flue gas in nickel foam production, and more specifically, to a method for treating oxidation flue gas in nickel foam production. Background Technology

[0002] In nickel foam production, the oxidation roasting process generates high-temperature flue gas at approximately 500–700°C. Its main components are N2, O2, CO2, and H2O, and it also contains VOCs, tar, H2, CO, and acidic gases, along with molten droplets from the pyrolysis of polyurethane foam and nickel dust (nickel oxide and elemental nickel). Currently, the commonly used waste gas treatment process in the industry involves first rapidly cooling the high-temperature flue gas to below 200°C using water spray, then sending it to a regenerative thermal oxidizer (RTO) for secondary heating and incineration, followed by dust removal and acid removal facilities. This traditional process results in a significant loss of high-grade heat energy during the "cooling-then-heating" process. Furthermore, after rapid cooling, the flue gas must re-cross the 250–500°C dioxin synthesis temperature window during the subsequent heating stage, objectively increasing the risk of dioxin formation.

[0003] In addition to the aforementioned energy consumption and environmental risks, this traditional process faces several prominent challenges in actual production, severely restricting production efficiency, working environment, and environmental compliance. Firstly, the molten droplets generated from the pyrolysis of polyurethane foam are carried into the flue gas duct by the flue gas. Due to the rapid cooling effect of the front-end water spray, the flue gas temperature drops sharply, causing the molten material to quickly condense and adhere to the inner wall of the pipe in a viscous state. Under the influence of residual heat, the adhered material undergoes smoldering and localized combustion, leading to long-term accumulation and coking and blockage of the flue gas duct. This not only affects the flue gas flow efficiency but also poses safety hazards such as fires. Secondly, in the water-cooling section of the flue gas duct, nickel dust, carbon black, tar mist, and water vapor mix to form wet ash. This wet ash easily adheres to the pipe wall and hardens, requiring daily manual high-pressure water flushing of the flue gas duct. This results in a harsh working environment, high labor intensity, and frequent high-pressure water flushing, accelerating the corrosion of the flue gas duct's metal walls and significantly increasing equipment maintenance and replacement costs. In addition, the process of spraying water to cool down generates a large amount of wastewater containing high concentrations of organic matter, tar and nickel dust. This type of wastewater is difficult to degrade and cannot be treated by the existing integrated wastewater treatment system in the plant area. It is necessary to build a special wastewater treatment facility that includes pretreatment, physicochemical treatment and biochemical treatment, which requires high investment, large area and expensive operating costs.

[0004] The root cause of the above problems lies in the technical bias inherent in traditional processes: the industry generally believes that high-temperature flue gas containing tar and molten material must be cooled to a low temperature before entering subsequent treatment equipment, otherwise it will clog pipes and adhere to equipment, thus forming a solidification process route of "cooling down first and then heating up". However, this technical bias ignores the fact that the molten material and tar in the high-temperature flue gas are actually in a gaseous or low-viscosity liquid state when maintained at a high temperature, and will not condense and adhere to the pipe wall; what really causes coking and blockage is the water spray quenching operation itself. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method and system for treating oxidizing flue gas in nickel foam production that can simultaneously achieve efficient utilization of thermal energy and suppression of dioxin sources. The technical solution is as follows: A method for treating oxidation flue gas in nickel foam production, wherein the oxidation flue gas temperature is 500-700℃, and contains one or more of the following: O2, acidic gases, elemental nickel, nickel oxide, VOCs, tar, H2, CO, carbon black, and polyurethane pyrolysis melt; characterized in that the treatment method includes the following steps: Pretreatment process: The oxidation flue gas is collected and kept warm, and the first gas with a temperature drop of ≤30℃ is output; Oxidation and combustion process: VOCs, tar, H2, CO, carbon black and polyurethane pyrolysis melt present in the first gas are removed by oxidation and combustion, and nickel is oxidized to nickel oxide, and the second gas is output. Waste heat recovery process: The second gas is subjected to heat exchange treatment to obtain the third gas; Post-treatment process: The third gas is subjected to dust removal and acid removal treatment to obtain clean exhaust gas.

[0006] The advantages of the method for treating oxidation flue gas in the production of foamed nickel of the present invention are: (1) The pretreatment process heats the oxidation flue gas to the oxidation combustion process under the condition of temperature drop ≤30℃, so that the tar and polyurethane pyrolysis melt in the high temperature flue gas of 500~700℃ are always maintained in a gaseous state or a low viscosity liquid state, which fundamentally eliminates the problems of melt condensation and flue coking blockage caused by front-end water spraying rapid cooling in the traditional process, eliminates the high-intensity manual operation of high-pressure water flushing of flue, and avoids the generation of flushing wastewater containing polyurethane pyrolysis melt and nickel dust and the construction and investment of supporting wastewater treatment facilities. (2) The first gas after heat preservation enters the oxidation combustion process directly at a temperature close to that of the oxidation flue gas, making full use of the high-grade sensible heat carried by the oxidation flue gas itself as the combustion heat source, avoiding the energy ineffective loss of the traditional process of "cooling down first and then heating up", and significantly reducing the consumption of auxiliary fuel. (3) The thermal oxidation reaction kinetics of organic compounds such as VOCs (including volatile chlorinated organic compounds), tar, and polyurethane pyrolysis melt at high temperatures are already relatively fast. The nickel oxide particles carried by the first gas itself can act as a catalyst to further reduce the ignition temperature and complete conversion temperature of some difficult-to-decompose organic compounds (such as polycyclic aromatic hydrocarbons and chlorinated organic compounds). Especially in the initial stage of heating and when the furnace temperature fluctuates, it plays a stabilizing catalytic combustion-supporting role, realizing the efficient and thorough decomposition of organic pollutants. At the same time, the nickel element carried by itself is oxidized to nickel oxide during the combustion process. The generated nickel oxide further supplements the catalytically active components, forming a self-reinforcing cycle of "catalysis-generation-re-catalysis". It can maintain high catalytic activity without the need to add additional catalysts. (4) When the heat is recovered through the waste heat recovery process, since the volatile chlorinated organic compounds have been removed by the oxidation combustion process, the synthesis of dioxins is effectively inhibited due to the lack of raw materials. Thus, the efficient utilization of thermal energy and the source inhibition of dioxins are realized at the same time.

[0007] As a further improvement to the above treatment method: In the pretreatment process, negative pressure suction is used to collect the oxidation flue gas. The negative pressure inside the collection pipe is -50 to -200 Pa, and the collection pipe is insulated with an aluminum silicate fiber insulation layer with a thickness of 80 to 150 mm. This negative pressure suction ensures that the gas escape point is under a slight negative pressure, preventing gas from overflowing into the workshop. The aluminum silicate fiber insulation layer has the characteristics of high temperature resistance and low thermal conductivity, and its thickness of 80 to 150 mm achieves good insulation effect.

[0008] As a further improvement to the above treatment method, in the oxidation combustion process, the combustion temperature is 850–950°C, and the residence time is ≥1.5 seconds. This ensures that VOCs, tar, and polyurethane pyrolysis products are fully oxidized and decomposed under catalytic conditions.

[0009] As a further improvement to the above-mentioned treatment method: In the oxidation combustion process, a staged air distribution method is adopted to supplement the first gas with combustion-supporting air. The excess air coefficient of the first-stage air distribution zone is 0.7 to 0.9, and the total excess air coefficient of the first-stage and second-stage air distribution zones is 1.05 to 1.3. The first-stage air distribution zone supplies a portion of the combustion-supporting air to assist ignition and achieve initial ignition of the combustible components. The second-stage air distribution zone supplements the remaining combustion-supporting air to ensure complete combustion of the combustibles. Thus, through staged air supply, local high temperatures in the furnace caused by local excess oxygen are avoided, which is conducive to a uniform temperature distribution in the furnace.

[0010] As a further improvement to the above-mentioned treatment method: in the oxidation combustion process, the first gas adopts a swirling flow, while the combustion air adopts a direct flow. Thus, the swirling flow of the first gas enhances the turbulent mixing intensity and extends its effective stroke in the furnace, which is beneficial for stabilizing the flame and improving the burnout rate; the direct flow of the combustion air can penetrate the swirling gas mass to achieve stratified oxygen distribution, ensuring that oxygen is evenly penetrated into the reaction zone.

[0011] As a further improvement to the above-mentioned treatment method: in the oxidation combustion process, when the furnace temperature is below 850°C, auxiliary fuel is added to the first-stage air distribution zone. Therefore, when the calorific value of the first gas itself is insufficient to maintain the combustion temperature, adding auxiliary fuel can quickly raise the furnace temperature to the set range, ensuring the catalytic oxidation combustion effect.

[0012] As a further improvement to the above treatment method, in the waste heat recovery process, the outlet temperature of the third gas is 180–220°C. Therefore, this outlet temperature of 180–220°C is higher than the acid dew point, which can prevent acid condensation corrosion in subsequent equipment and pipelines.

[0013] As a further improvement to the above treatment method, the waste heat recovery process employs a two-stage cooling system: first, the waste heat is cooled to 550–600°C by a waste heat boiler, and then rapidly cooled to 180–220°C. This allows the waste heat boiler stage to efficiently recover high-grade heat energy for steam production or heating, while the rapid cooling process quickly crosses the dioxin resynthesis temperature window (250–500°C), further inhibiting dioxin formation. Furthermore, the 180–220°C temperature is above the acid dew point, preventing condensation, corrosion, and blockage in subsequent equipment and pipelines.

[0014] As a further improvement to the above treatment method, the rapid cooling process employs spray evaporation, with the atomized water droplets having a diameter ≤100μm, and the temperature dropping from 550–600℃ to 180–220℃ in ≤1 second. Thus, the droplet diameter ≤100μm provides a large specific surface area for rapid evaporation and heat absorption, and the ≤1-second cooling time ensures an extremely short residence time of the gas within the active dioxin synthesis temperature range (250–500℃), effectively suppressing the resynthesis of dioxins during the cooling process.

[0015] As a further improvement to the above treatment method, the post-treatment process also includes adsorption treatment with activated carbon after the deacidification treatment. Therefore, activated carbon has a good adsorption capacity for residual trace organic matter, dioxins, and heavy metal vapors, ensuring that emissions meet stringent environmental standards.

[0016] A system for treating oxidation flue gas in nickel foam production includes a pretreatment unit, an oxidation combustion unit, a waste heat recovery unit, and a post-treatment unit connected in sequence. The pretreatment unit includes a collection pipe and an insulation layer installed on the outer wall of the collection pipe, with the inlet of the collection pipe connected to the outlet of the oxidation flue gas. The oxidation combustion unit includes a combustion furnace equipped with an ignition device and an air distribution device. The waste heat recovery unit includes a heat exchange device with its inlet connected to the exhaust port of the combustion furnace. The post-treatment unit includes a dust removal device and a deacidification device arranged in sequence along the gas flow direction.

[0017] The advantages of the oxidation flue gas treatment system in the production of foamed nickel of the present invention are: (1) The pretreatment unit is directly connected to the oxidation flue gas outlet by a collection pipe with a heat insulation layer, so that the high temperature oxidation flue gas is kept at a high temperature throughout the transportation process. The tar and polyurethane pyrolysis melt in the pipe are always in a gaseous state or a low viscosity liquid state and do not condense on the pipe wall. The structure eliminates the stubborn problem of flue coking and blockage in the traditional system. There is no need to set up a front-end water spray quenching device and supporting wastewater treatment facilities, and the system structure is greatly simplified. (2) The combustion furnace is equipped with an ignition device and an air distribution device, so that the high temperature gas transported here can be directly catalytically oxidized and combusted in the combustion furnace, effectively removing pollutants such as VOCs, tar, and polyurethane pyrolysis melt, and inhibiting the generation of dioxins from the source. The nickel oxide particles carried by the furnace also have the function of catalysts. There is no need to set up a separate catalyst filling bed or replace the catalyst module regularly, which reduces the complexity of the equipment and the cost of operation and maintenance. (3) The air inlet of the heat exchange device is directly connected to the exhaust port of the combustion furnace. The high-temperature gas generated by combustion can enter the waste heat recovery unit without intermediate buffering, which effectively reduces heat loss and improves the waste heat recovery efficiency. (4) After full combustion and cooling, the post-treatment unit completes particulate matter capture and acid gas removal in sequence, so that the exhaust gas meets the emission standards.

[0018] As a further improvement to the above-mentioned treatment system, the insulation layer is an aluminum silicate fiber insulation layer with a thickness of 80-150mm. Aluminum silicate fiber has the characteristics of high temperature resistance, low thermal conductivity, and light weight. The 80-150mm thickness ensures insulation performance without significantly increasing the pipe's outer diameter and support load, facilitating on-site installation and maintenance.

[0019] As a further improvement to the aforementioned processing system, the air distribution device includes a primary air distribution structure and a secondary air distribution structure sequentially arranged on the combustion furnace. The primary air distribution structure is located in the front section of the combustion furnace, and the secondary air distribution structure is located in the middle section of the combustion furnace. This improves the burnout rate.

[0020] As a further improvement to the aforementioned processing system: the combustion furnace inlet is equipped with a swirling structure, and the primary and secondary air distribution structures include air supply nozzles arranged in a ring along the radial direction of the combustion furnace. Thus, the swirling structure creates a rotating flow field in the flue gas to enhance mixing and extend its travel distance, while the air distribution inlet uses air supply nozzles to directionally deliver air into specific areas. This combination of two flow structures helps stabilize the flame and achieve precise stratified oxygen supply.

[0021] As a further improvement to the aforementioned processing system, the oxidation combustion unit also includes an auxiliary fuel supply device. The feed nozzle of the auxiliary fuel supply device is located at the primary air distribution structure and feeds fuel radially along the combustion furnace. A temperature sensor is installed inside the combustion furnace, and the temperature sensor is signal-connected to the control valve of the auxiliary fuel supply device. This enables automatic control of the combustion temperature.

[0022] As a further improvement to the aforementioned treatment system, the heat exchange device includes a waste heat boiler and a quench tower arranged sequentially along the gas flow direction, with the exhaust port of the waste heat boiler connected to the inlet of the quench tower. Thus, the waste heat boiler recovers high-grade heat energy, and the quench tower achieves rapid cooling across the dioxin synthesis temperature window, thus balancing heat energy utilization and dioxin synthesis inhibition.

[0023] As a further improvement to the aforementioned processing system, the quench tower is equipped with a gas-liquid two-phase atomizing nozzle, which is connected to a water supply pipeline and a compressed air pipeline. This allows water to be atomized into fine droplets, providing a larger evaporation area and a faster heat and mass transfer rate, achieving rapid cooling and shortening the residence time within the dioxin synthesis temperature range.

[0024] As a further improvement to the above-mentioned treatment system: the dust removal device adopts a metal filter cartridge dust collector; the acid removal device is a spray tower. Therefore, the metal filter cartridge dust collector has good temperature resistance, can adapt to higher gas temperatures, and effectively captures nickel-containing fine particles to achieve nickel resource recovery and utilization.

[0025] As a further improvement to the aforementioned treatment system, the post-treatment unit also includes an activated carbon adsorption device located downstream of the deacidification unit. This ensures that the exhaust gas meets emission standards.

[0026] As a further improvement to the aforementioned treatment system, an induced draft fan is also included, located downstream of the post-treatment unit. This ensures that each treatment unit operates under negative pressure, preventing gas leakage from the connections. Simultaneously, the induced draft fan operates in a low-temperature, clean gas environment, which helps extend its service life and reduce maintenance frequency.

[0027] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0028] The accompanying drawings, which form part of this invention, are used to aid in understanding the invention. The content provided in the drawings and their related descriptions can be used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of the structure of the oxidation flue gas treatment system in the production of nickel foam according to the present invention.

[0029] Figure 2 This is a schematic diagram of the structure of the oxidation combustion unit in the oxidation flue gas treatment system of the nickel foam production of the present invention.

[0030] The relevant markings in the above figures are: 100-Oxidation roasting furnace, 110-Collection pipe, 200-Combustion furnace, 300-Auxiliary fuel supply device, 410-Waste heat boiler, 420-Quick cooling tower, 510-Dust removal device, 520-Acid removal device, 530-Activated carbon adsorption device, 210-Ignition device, 220-Air distribution device, 221-Primary air distribution structure, 222-Secondary air distribution structure, 230-Swirl structure, 240-Air supply nozzle, 310-Feeding nozzle, 320-Temperature sensor, 330-Control valve. Detailed Implementation

[0031] The present invention will now be clearly and completely described in conjunction with the accompanying drawings. Those skilled in the art will be able to implement the present invention based on these descriptions. Before describing the present invention in conjunction with the accompanying drawings, it should be particularly noted that: The technical solutions and features provided in the various parts of this invention, including the following description, can be combined with each other without conflict.

[0032] Furthermore, the embodiments of the present invention described below are generally only some, not all, of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0033] Regarding the terminology and units used in this invention: The terms "comprising," "having," and any variations thereof in the specification, claims, and related parts of this invention are intended to cover non-exclusive inclusion.

[0034] A typical production process for nickel foam involves using polyurethane foam as a skeleton template, depositing a nickel layer on the template through conductive treatment and electroplating, followed by oxidative roasting to remove the polyurethane foam skeleton and reduce nickel oxide to nickel, thus obtaining nickel foam. The oxidative roasting is carried out in a roasting furnace, producing oxidative flue gas at a temperature of 500–700°C, containing N2, O2, CO2, H2O, VOCs, tar, H2, CO, carbon black, acidic gases, pyrolysis melt of polyurethane, elemental nickel, and nickel oxide. The specific implementation of the method for treating the oxidative flue gas in the production of nickel foam according to this invention includes the following steps: Pre-treatment process: The oxidation flue gas is collected and insulated to output a first gas with a temperature drop of ≤30℃. The oxidation flue gas is collected by negative pressure suction, with a negative pressure of -50 to -200 Pa in the collection pipeline. The collection pipeline is insulated with an aluminum silicate fiber insulation layer with a thickness of 80 to 150 mm.

[0035] Oxidation and combustion process: The first gas is ignited, using nickel oxide as a catalyst to catalytically combust VOCs, tar, H2, CO, carbon black, and polyurethane pyrolysis melt, oxidizing elemental nickel to nickel oxide, which is then output as the second gas. The combustion temperature is 850–950℃, and the residence time is ≥1.5 seconds. A staged air distribution system supplements the first gas with combustion air. The excess air coefficient in the first stage air distribution zone is 0.7–0.9, and the total excess air coefficient between the first and second stage air distribution zones is 1.05–1.3. The first gas flows in a swirling stream, while the combustion air flows in a direct stream. When the furnace temperature drops below 850℃, auxiliary fuel, specifically natural gas, is added to the first stage air distribution zone.

[0036] Waste heat recovery process: The second gas undergoes heat exchange treatment to obtain the third gas; the outlet temperature of the third gas is 180–220℃. A two-stage cooling process is employed: first, the gas is cooled to 550–600℃ by a waste heat boiler, and then rapidly cooled to 180–220℃. The rapid cooling process uses spray evaporation, with atomized water droplets ≤100μm in diameter, and the time to cool from 550–600℃ to 180–220℃ is ≤1 second.

[0037] Post-processing steps: The third gas is subjected to dust removal, acid removal and adsorption treatment to obtain clean exhaust gas.

[0038] To facilitate the implementation of the above-mentioned processing method, the present invention provides a system for treating oxidation flue gas in nickel foam production. Figure 1 This is a schematic diagram of the structure of the oxidation flue gas treatment system in the production of nickel foam according to the present invention. Figure 2 This is a schematic diagram of the structure of the oxidation combustion unit in the oxidation flue gas treatment system of the nickel foam production of the present invention.

[0039] like Figure 1-2 The oxidation flue gas treatment system shown in the nickel foam production process includes a pretreatment unit, an oxidation combustion unit, a waste heat recovery unit, and a post-treatment unit connected in sequence.

[0040] The pretreatment unit includes a collection pipe 110 and an insulation layer disposed on the outer wall of the collection pipe 110. The inlet of the collection pipe 110 is connected to the oxidation flue gas outlet of the oxidation roasting furnace 100 in the production of nickel foam. The insulation layer is an aluminum silicate fiber insulation layer with a thickness of 80-150 mm, which is determined according to the length of the collection pipe 110. The longer the pipe, the thicker the insulation layer.

[0041] The oxidation combustion unit includes a combustion furnace 200 and an auxiliary fuel supply device 300. The combustion furnace 200 is equipped with an ignition device 210 and an air distribution device 220. The air distribution device 220 includes a primary air distribution structure 221 and a secondary air distribution structure 222 sequentially arranged on the combustion furnace 200. The primary air distribution structure 221 is located at the front section of the combustion furnace 200, and the secondary air distribution structure 222 is located in the middle section of the combustion furnace 200. A swirl structure 230 is provided at the inlet of the combustion furnace 200. The primary air distribution structure 221 and the secondary air distribution structure 222 include air supply nozzles 240 arranged in a ring and discharging air radially along the combustion furnace 200. The feed nozzle 310 of the auxiliary fuel supply device 300 is located at the primary air distribution structure 221 and feeds fuel radially along the combustion furnace 200. A temperature sensor 320 is provided inside the combustion furnace 200, and the temperature sensor 320 is signal-connected to the control valve 330 of the auxiliary fuel supply device 300.

[0042] The waste heat recovery unit includes a heat exchange device, the air inlet of which is connected to the exhaust port of the combustion furnace 200. The heat exchange device includes a waste heat boiler 410 and a quench tower 420 arranged sequentially along the gas flow direction, the exhaust port of the waste heat boiler 410 being connected to the air inlet of the quench tower 420. The quench tower 420 is equipped with a gas-liquid two-phase atomizing nozzle, which is connected to a water supply pipeline and a compressed air pipeline.

[0043] The post-treatment unit includes a dust removal device 510, an acid removal device 520, and an activated carbon adsorption device 530 arranged sequentially along the gas flow direction. The dust removal device 510 is a metal filter dust collector; the acid removal device 520 is a spray tower.

[0044] An induced draft fan is installed downstream of the post-processing unit.

[0045] The following two application examples illustrate the beneficial effects of the above processing method and system.

[0046] Application Example 1 (Self-Supporting Combustion) The parameters of the oxidation flue gas discharged from the oxidation baking furnace of a certain nickel foam production line are as follows: temperature 600~610℃, air volume 14850 Nm³. 3 / h. The composition of the oxidation flue gas is: N2 78.56 vol%, O2 0.82 vol%, CO2 8.72 vol%, H2O 9.28 vol%, H2 0.41 vol%, CO 2.01 vol%, VOCs 3814 mg / m³ 3 Tar 559mg / m³ 3 Carbon black 192mg / m 3 HCl 82mg / m 3 SO2 36mg / m 3 365 mg / m³ of polyurethane pyrolysis melt 3 Nickel element 306 mg / m³ 3 Nickel oxide 218 mg / m 3 .

[0047] Pretreatment process: Oxidation flue gas is collected using a negative pressure suction method. The negative pressure inside the collection pipeline is -120Pa, and the insulation layer is made of aluminum silicate fiber with a thickness of 125mm. The temperature of the first output gas is 585~590℃, with a temperature drop of ≤25℃.

[0048] Oxidation combustion process: The first gas enters the combustion furnace through a swirling structure, with a residence time of 2.1 s; the excess air coefficient in the first-stage air distribution zone is 0.80, and the total excess air coefficient is 1.10; due to the sufficient calorific value of the organic matter, the furnace temperature is stably maintained at 870–880℃, requiring no additional natural gas and achieving complete self-sustaining combustion; in the output second gas: VOCs were not detected, and CO < 28 mg / m³ 3 Tar, carbon black, polyurethane pyrolysis melt, and H2 were all completely burned off. Elemental nickel was completely oxidized to nickel oxide. Particulate matter (mainly nickel oxide) was 608 mg / m³. 3 .

[0049] Waste heat recovery process: The second gas is first cooled to 570-575℃ in a waste heat boiler, producing approximately 2.6t / h of 0.6MPa (gauge pressure) saturated steam as a byproduct, and recovering approximately 1.64×10⁻⁶ heat. 6 kcal / h, steam is used for the preheating process of nickel foam production; then it is treated by spray evaporation in a quench tower, the atomized water droplet size is ≤100μm, and the cooling time is <1s; the output third gas temperature is 192~198℃.

[0050] Post-treatment process: The third gas passes through a metal filter dust collector for dust removal, with an outlet particulate matter concentration ≤1.6 mg / m³. 3 After deacidification by alkaline solution in the spray tower, the outlet HCl is ≤8mg / m³. 3 SO2 ≤ 9 mg / m³ 3 The residual trace organic matter and dioxins were adsorbed by an activated carbon adsorption device, yielding a dioxin concentration of 0.032 ng TEQ / m³. 3 The clean exhaust gas is discharged through the chimney by the induced draft fan.

[0051] Application Example 2 (Small Amount of Afterburner) The parameters of the oxidation flue gas discharged from the oxidation baking furnace of a certain nickel foam production line are as follows: temperature 550~560℃, air volume 11580 Nm³. 3 / h. The composition of the oxidation flue gas is: N2 81.21 vol%, O2 0.76 vol%, CO2 7.55 vol%, H2O 8.12 vol%, H2 0.35 vol%, CO 1.81 vol%, VOCs 3036 mg / m³ 3 Tar 376mg / m³ 3 Carbon black 128mg / m 3 HCl 58mg / m 3 SO2 24mg / m 3 245 mg / m³ of polyurethane pyrolysis melt 3 Nickel element 248 mg / m³ 3 Nickel oxide 165mg / m 3 .

[0052] Pretreatment process: Oxidation flue gas is collected using negative pressure suction, with a negative pressure of -85 Pa inside the collection pipe. The insulation layer is made of aluminum silicate fiber with a thickness of 105 mm. The temperature of the first output gas is 532–537℃, with a temperature drop of ≤28℃.

[0053] Oxidation combustion process: The first gas enters the combustion furnace through a swirling structure, with a residence time of 1.8s; the excess air coefficient in the first-stage air distribution zone is 0.75, and the total excess air coefficient is 1.20; due to the low concentration of organic matter, the furnace temperature cannot be self-sustaining to 850℃, so natural gas is supplemented to the first-stage air distribution zone, with a natural gas consumption ≤78Nm³.3 The combustion temperature remained stable at 880–890℃ per hour. In the output second gas: VOCs were not detected, and CO < 25 mg / m³. 3 Tar, carbon black, polyurethane pyrolysis melt, and H2 were completely burned off; all elemental nickel was oxidized to nickel oxide; particulate matter (mainly nickel oxide) was 479 mg / m³. 3 .

[0054] Waste heat recovery process: The second gas is first cooled to 563-567℃ in a waste heat boiler, producing approximately 2.2t / h of 0.6MPa (gauge pressure) saturated steam as a byproduct, and recovering approximately 1.40×10⁻⁶ heat. 6 kcal / h, steam is used for heating in the plant area; then it is treated by spray evaporation in a quench tower, the atomized water droplet size is ≤100μm, the cooling time is <1s, and the output third gas temperature is 205~210℃.

[0055] Post-treatment process: The third gas is dusted by a metal filter dust collector, with an outlet particulate matter concentration ≤1.8mg / m³; it is then deacidified by alkaline solution in a spray tower, with an outlet HCl concentration ≤6mg / m³. 3 SO2 ≤ 7 mg / m³ 3 The residual trace organic matter and dioxins were adsorbed by an activated carbon adsorption device, yielding a dioxin concentration of 0.038 ng TEQ / m³. 3 The clean exhaust gas is discharged through the chimney by the induced draft fan.

[0056] The foregoing has described the relevant content of the present invention. Those skilled in the art will be able to implement the present invention based on these descriptions. All other embodiments obtained by those skilled in the art based on the above description of the present invention without inventive effort should fall within the scope of protection of the present invention.

Claims

1. A method for treating oxidation flue gas in nickel foam production, wherein the oxidation flue gas has a temperature of 500–700°C and contains one or more of the following: O2, acidic gases, elemental nickel, nickel oxide, VOCs, tar, H2, CO, carbon black, and polyurethane pyrolysis melt, characterized in that: The processing method includes the following steps: Pretreatment process: The oxidation flue gas is collected and kept warm, and the first gas with a temperature drop of ≤30℃ is output; Oxidation and combustion process: VOCs, tar, H2, CO, carbon black and polyurethane pyrolysis melt present in the first gas are removed by oxidation and combustion, and nickel is oxidized to nickel oxide, and the second gas is output. Waste heat recovery process: The second gas is subjected to heat exchange treatment to obtain the third gas; Post-treatment process: The third gas is subjected to dust removal and acid removal treatment to obtain clean exhaust gas.

2. The method for treating oxidation flue gas in nickel foam production as described in claim 1, characterized in that: In the pretreatment process, the oxidation flue gas is collected by negative pressure suction. The negative pressure in the collection pipeline is -50 to -200 Pa. The collection pipeline is insulated with aluminum silicate fiber insulation layer with a thickness of 80 to 150 mm.

3. The method for treating oxidation flue gas in nickel foam production as described in claim 1, characterized in that: In the oxidation combustion process, the combustion temperature is 850-950℃ and the residence time is ≥1.5 seconds.

4. The method for treating oxidation flue gas in nickel foam production as described in claim 3, characterized in that: In the oxidation combustion process, a staged air distribution method is used to supplement the first gas with combustion air. The excess air coefficient of the first stage air distribution zone is 0.7 to 0.9, and the total excess air coefficient of the first stage air distribution zone and the second stage air distribution zone is 1.05 to 1.

3.

5. The method for treating oxidation flue gas in nickel foam production as described in claim 4, characterized in that: In the oxidation and combustion process, the first gas adopts a swirling flow, while the combustion air adopts a direct flow.

6. The method for treating oxidation flue gas in nickel foam production as described in claim 4, characterized in that: In the oxidation combustion process, when the furnace temperature is below 850℃, auxiliary fuel is added to the first-stage air distribution zone.

7. The method for treating oxidation flue gas in nickel foam production as described in claim 1, characterized in that: In the waste heat recovery process, the outlet temperature of the third gas is 180–220°C.

8. The method for treating oxidation flue gas in nickel foam production as described in claim 7, characterized in that: The waste heat recovery process employs a two-stage cooling process: first, the waste heat is cooled to 550–600°C by a waste heat boiler, and then rapidly cooled to 180–220°C.

9. The method for treating oxidation flue gas in nickel foam production as described in claim 8, characterized in that: The rapid cooling process uses a spray evaporation method, with the droplet size of the sprayed atomized water ≤100μm, and the time to cool from 550~600℃ to 180~220℃ is ≤1 second.

10. The method for treating oxidation flue gas in nickel foam production as described in claim 1, characterized in that: The post-treatment process also includes adsorption treatment with activated carbon after deacidification.

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