A method and system for multi-pollutant industrial flue gas purification

Abstract

A multi-pollutant industrial flue gas purification method, the method comprises the following steps: 1) real-time monitoring the temperature of the original flue gas, and adjusting the original flue gas to the set decarburization temperature; 2) the temperature-adjusted original flue gas is subjected to dust removal and decarburization treatment at the same time to obtain decarburization flue gas; 3) the decarburization flue gas is subjected to denitration treatment to obtain denitration flue gas; 4) the denitration flue gas is subjected to cooling and desulfurization treatment to obtain clean flue gas. The present application is based on nickel-silicon-based intermetallic compound porous material coated with nickel-copper alloy porous membrane, which realizes efficient interception of dust at the source of flue gas treatment, realizes synchronous dust removal and decarburization, avoids the heat loss of the single-function combined process of dust removal and decarburization in the flue gas conveying process, improves the heat utilization rate. Avoid the poisoning of dust to the subsequent catalyst, improve the efficiency of subsequent denitration and desulfurization, and have high temperature resistance, acid, alkali and water corrosion resistance, and can work stably in complex industrial flue gas atmosphere in many fields.

Description

Technical Field

[0001] This invention relates to an industrial flue gas purification method and system, specifically to a multi-pollutant industrial flue gas purification method and system, belonging to the field of industrial flue gas purification technology. Background Technology

[0002] Industrial waste gases produced using fossil fuels such as coal often contain a certain concentration of carbon monoxide. These include gases from boilers, heating furnaces, sintering furnaces, and coke ovens. Carbon monoxide is a colorless, odorless, and toxic gas that can participate in the formation of photochemical smog, causing harm. High concentrations can cause varying degrees of poisoning symptoms, damaging the brain, heart, liver, kidneys, and other tissues. Emissions should be minimized. Currently, in boiler and heating furnace processes, except for coke oven / blast furnace waste gases with higher calorific value which are purified and used as fuel, most low-concentration (around 1%) carbon monoxide is directly emitted with the flue gas.

[0003] Currently, industrial flue gas treatment mainly targets particulate matter, sulfur dioxide, and nitrogen oxides, while other pollutants are regulated separately based on the characteristics of different industries. The environmental protection process used in the coal-fired power industry typically involves: high-dust, medium-high temperature SCR denitrification → air preheater heat exchange → electrostatic precipitator → desulfurization → dust removal. In non-power industries such as steel sintering, the environmental protection process typically involves: electrostatic precipitator → desulfurization → low / medium-high temperature SCR denitrification. For glass furnaces, the environmental protection process typically involves: waste heat boiler → (flue gas conditioning) → high-temperature electrostatic precipitator → SCR denitrification, etc.

[0004] The above environmental protection processes have the following problems: 1) The environmental protection modules have limited functions, the process is lengthy, the system occupies a large area, and the investment cost is high; 2) The system operating costs and energy consumption are relatively high, and the process flow design needs to be further optimized; 3) The energy utilization within the system is insufficient, and the synergy between different environmental protection modules needs to be further improved; 4) Conventional electrostatic precipitators and bag filters have high requirements for flue gas temperature; 5) The system functions are usually limited to the treatment of conventional pollutants, and none of them are equipped with carbon monoxide purification functions. Summary of the Invention

[0005] To address the problems of existing environmental protection processes, such as limited functionality, lengthy processes, insufficient energy utilization, and high temperature requirements for conventional dust removal equipment, this invention proposes a multi-pollutant industrial flue gas purification method and system. It proposes a dust removal and decarbonization device that performs dust removal and decarbonization simultaneously, and designs a purification system including a dust removal and decarbonization device, a denitrification device, and a desulfurization device. The dust removal and decarbonization device is an intermetallic compound system, possessing excellent resistance to high temperatures and acid, alkali, and water corrosion, enabling it to cope with complex industrial flue gas atmospheres. Simultaneously, it avoids the risks of damage to traditional electrostatic precipitators and bag filter ablation and perforation under high-temperature environments.

[0006] According to a first embodiment of the present invention, a method for purifying multi-pollutant industrial flue gas is provided.

[0007] A method for purifying multi-pollutant industrial flue gas, the method comprising the following steps:

[0008] 1) Monitor the temperature of the raw flue gas in real time and adjust the raw flue gas to the set decarbonization temperature;

[0009] 2) The original flue gas after temperature adjustment is subjected to dust removal and decarbonization treatment at the same time to obtain decarbonized flue gas;

[0010] 3) The decarbonized flue gas is then subjected to denitrification treatment to obtain denitrified flue gas;

[0011] 4) After cooling the denitrification flue gas, desulfurization treatment is carried out to obtain clean flue gas.

[0012] Preferably, the method further includes: 5) recycling the heat released during the cooling process of the denitrification flue gas to step 1) as a heat source for adjusting the temperature of the original flue gas or as a heat source for supplementing the heat of the clean flue gas.

[0013] Preferably, in step 1), the raw flue gas includes nitrogen oxides, sulfur dioxide, carbon monoxide, and dust.

[0014] In step 1), the decarburization temperature is 250–400°C, preferably 300–350°C;

[0015] Preferably, adjusting the raw flue gas to the set decarbonization temperature specifically includes:

[0016] (a1) When the original flue gas temperature T < 250℃, preferably T < 300℃, the flue gas temperature is too low. The heat released during the cooling process of the denitrified flue gas or additional heat is introduced to raise the flue gas temperature to above 250℃, preferably above 300℃.

[0017] (a2) When the original flue gas temperature T>400℃, preferably T>350℃, the flue gas temperature is too high. The flue gas temperature is reduced to below 400℃, preferably below 350℃. Preferably, the heat of the flue gas is recycled to supplement the heat of the clean flue gas.

[0018] Preferably, in step 1), the dust removal and decarbonization treatment specifically involves using a nickel-silicon-based intermetallic compound porous material with a nickel-copper alloy porous membrane coated on its surface as a catalyst bed to simultaneously filter out dust and oxidize and remove CO.

[0019] Preferably, the pore size of the nickel-copper alloy porous membrane is 3-5 μm and the membrane thickness is 0.3-0.8 mm.

[0020] Preferably, the nickel-silicon-based metal compound porous material has a tubular structure with a pore size of 30–50 μm and a wall thickness of 5–8 mm.

[0021] Preferably, the nickel-silicon-based intermetallic compound includes Ni, Si, and optionally includes or excludes one or more elements selected from Ce, Fe, Mn, Cu, and Co; preferably, the ratio of the mass of Ni, Si, and the sum of the masses of other elements is 70–85:11–20:2–8, and more preferably 77–83:13–17:3–7.

[0022] Preferably, the nickel-copper alloy porous membrane includes Ni, Cu, and optionally includes or excludes one or more elements selected from Fe, Mn, and Co; preferably, the ratio of the mass of Ni, Cu, and the sum of the masses of other elements is 20-40:5-15:2-8, and more preferably 25-35:7-13:4-6.

[0023] Preferably, the nickel-silicon-based metal compound porous material with a nickel-copper alloy porous film on its surface is obtained by first obtaining the nickel-silicon-based metal compound porous material by powder sintering, and then coating the surface of the nickel-copper-containing slurry onto the surface of the nickel-silicon-based metal compound porous material and then performing a sintering treatment again.

[0024] Preferably, after obtaining the nickel-silicon-based metal compound porous material, it is first pre-reduced before the coating step.

[0025] Preferably, the method further includes: A) pre-oxidizing and calcining the nickel-silicon-based metal compound porous material with a nickel-copper alloy porous film on its surface before use.

[0026] Preferably, the pre-oxidation is carried out in oxygen-containing gas for 0.2 to 4 hours, more preferably 0.5 to 2 hours.

[0027] Preferably, the calcination temperature is 400–800°C, and more preferably 500–700°C.

[0028] Preferably, the calcination time is 2 to 4 hours, and more preferably 2.5 to 3.5 hours.

[0029] Preferably, the denitrification in step 3) is SCR denitrification.

[0030] Preferably, the cooling in step 4) is to cool the denitrification flue gas to 110-140°C, more preferably 120-130°C.

[0031] Preferably, the desulfurization in step 4) is activated carbon desulfurization.

[0032] According to a second embodiment of the present invention, a multi-pollutant industrial flue gas purification system is provided.

[0033] A multi-pollutant industrial flue gas purification system includes a temperature control device, a dust removal and decarbonization device, a denitrification device, and a desulfurization device connected in series. The dust removal and decarbonization device is a nickel-silicon-based intermetallic compound porous material with a nickel-copper alloy porous film coated on its surface.

[0034] Preferably, the system also includes a waste heat recovery device. The waste heat recovery device is connected to the heating unit of the temperature control device and / or the flue gas outlet of the desulfurization device.

[0035] This invention proposes a method for sequentially processing flue gas containing multiple pollutants through temperature regulation, dust removal and decarbonization, denitrification, and desulfurization to obtain clean flue gas. Specifically, before the dust removal and decarbonization step, the original flue gas is temperature-regulated to bring it within the optimal temperature range for dust removal and decarbonization. Furthermore, the dust removal and decarbonization are performed simultaneously using a nickel-silicon-based intermetallic compound porous material with a nickel-copper alloy porous film on its surface. This avoids the heat loss during flue gas transport caused by the single-function combined process of dust removal followed by decarbonization, improving heat utilization efficiency, reducing equipment footprint, and saving costs.

[0036] In this invention, the nickel-silicon-based intermetallic compound porous material with a nickel-copper alloy porous membrane on its surface has a double-layer structure. The outer nickel-copper alloy porous membrane includes Ni, Cu, and optionally includes or excludes one or more elements from Fe, Mn, and Co. The Ni-Cu alloy porous membrane dust removal has a wide acceptable range of flue gas temperature, avoiding the risks of damage and bag ablation perforation of traditional electrostatic precipitators under high-temperature environments, and the risk of flue gas condensation corroding electrostatic precipitators and causing bag clogging under low-temperature environments. The inner nickel-silicon-based intermetallic compound includes Ni, Si, and optionally includes or excludes one or more elements from Ce, Fe, Mn, Cu, and Co. It has high decarburization efficiency and a low risk of poisoning. Both the inner and outer layers of the nickel-silicon-based intermetallic compound porous material with a nickel-copper alloy porous membrane on its surface are intermetallic compound systems. In addition to high temperature resistance, it also has excellent resistance to acid, alkali, and water corrosion, and can work stably in complex industrial flue gas atmospheres in various fields.

[0037] In this invention, the outer layer (i.e., dust removal layer) of the nickel-silicon-based intermetallic compound porous material coated with a nickel-copper alloy porous membrane has a thickness of 0.2–1.2 mm (preferably 0.3–0.8 mm) and a pore size limited to 2–8 μm (preferably 3–5 μm). It can achieve high-precision ultra-clean dust interception in a high-temperature range of up to 600°C, with a dust interception rate of >99% and a filtration accuracy of ~1 μm. It effectively removes alkali metals, alkaline earth metals, and heavy metals from the dust, and effectively avoids the poisoning effect of harmful elements in the dust on the subsequent CO oxidation functional layer and SCR denitrification catalyst. On the other hand, the thin film layer ensures low resistance and high permeability when flue gas passes through.

[0038] In this invention, the inner layer (i.e., decarburization layer) of the nickel-silicon-based intermetallic compound porous material coated with a nickel-copper alloy porous membrane has a thickness of 3-12 mm (preferably 5-8 mm) and a pore size of 20-60 μm (preferably 30-50 μm). On the one hand, the larger pore size ensures rapid flue gas passage and low flue gas resistance, while the larger layer thickness serves as a support for the dust removal membrane, ensuring the mechanical strength of the system. On the other hand, the high-temperature flue gas after ultra-clean dust removal passes directly through, effectively avoiding heat loss during the flue gas transport process of single-function combined processes, achieving efficient utilization of thermal energy. Furthermore, the Ni-Si-based catalytic material possesses excellent water resistance, sulfur resistance, and CO catalytic activity, enabling efficient removal of CO under complex flue gas atmospheres.

[0039] In this invention, the inner and outer layers of the nickel-silicon-based intermetallic compound porous material coated with a nickel-copper alloy porous film are both made of intermetallic compound material system, which has excellent high temperature resistance and corrosion resistance, and can efficiently treat a variety of industrial flue gases. At the same time, the combination of inner and outer layer materials ensures excellent mechanical strength. After dust is intercepted and deposited in the dust removal functional layer, it can be removed by high-pressure air backflushing or water washing. The equipment is simple to maintain and has a long service life.

[0040] In this invention, based on multiple experimental studies, it was found that the optimal operating temperature of the nickel-silicon-based intermetallic compound porous material with a nickel-copper alloy porous film on its surface is 300-350℃ (preferably 310-340℃). The dust removal and decarbonization rate is improved by adjusting the temperature of the flue gas to the optimal temperature range of 250-400℃ (preferably 300-350℃) before dust removal and decarbonization.

[0041] In this invention, the flue gas, having undergone dust removal and decarbonization and absorbed the heat from the CO oxidation reaction, enters the denitrification process. The preceding process has already achieved high-precision dust removal. At this point, harmful elements in the flue gas that threaten the catalyst, such as alkali metals, alkaline earth metals, and heavy metals, have been almost completely eliminated. Therefore, the high-tech, low-cost, medium-high temperature SCR denitrification technology can be used.

[0042] The catalyst operates under excellent conditions, and the extremely low dust environment effectively reduces the risk of catalyst dust clogging. The denitrification process can utilize catalysts with a large number of pores, thus significantly reducing the catalyst volume, equipment size, and investment. Furthermore, the flue gas that has absorbed the heat of the CO oxidation reaction directly enters the denitrification system for the denitrification process, effectively utilizing the latent heat of reaction. At suitable flue gas temperatures, NO... x It has high removal efficiency, low risk of ammonium sulfate formation, high ammonia utilization rate, low ammonia slip value, and long catalyst life.

[0043] In this invention, since the flue gas temperature is high after denitrification, heat is recovered after the denitrification process and used to regulate the temperature of the raw flue gas before the dust removal and decarbonization process, so that the raw flue gas meets the temperature requirements for dust removal and decarbonization. Additionally, heat can be introduced into the clean flue gas duct to meet the requirement of "whitening" the flue gas, improve the appearance of emissions, and reduce the corrosive effect of low-temperature flue gas on flues and chimneys.

[0044] In this invention, if the desulfurization device adopts activated carbon dry desulfurization, the optimal temperature is 120-130℃. After the flue gas is heated by waste heat utilization, it can not only ensure the efficient removal of SO2, but also avoid the risk of heating / fire caused by flue gas temperature fluctuations and overheating, thus further improving the safety and stability of system operation.

[0045] In this invention, by adjusting the temperature of the original flue gas, performing high-temperature dust removal and decarbonization, high-temperature denitrification, waste heat utilization, and desulfurization, the flue gas temperature is well matched with the functional units throughout the entire process. The process flow design is reasonable, and the synergy between different functional units is high. Simultaneously, by utilizing simultaneous dust removal and decarbonization, efficient dust interception is achieved at the source of flue gas treatment, avoiding the toxic effects of dust on subsequent CO removal and denitrification catalysts. This allows the mature high-dust, high-temperature SCR process to use catalysts with large pore numbers, thereby significantly reducing equipment size and investment. Placing CO removal before the denitrification function enables direct utilization of the heat energy from the CO oxidation reaction. Furthermore, by adjusting the flue gas temperature and utilizing the waste heat of the flue gas after denitrification, one-step temperature regulation and one-step heat collection are achieved, greatly avoiding the low heat utilization efficiency problems caused by "heating and then cooling" or "cooling or heating" in traditional flue gas purification processes.

[0046] In this invention, the specific preparation method of the nickel-silicon-based intermetallic compound porous material with a nickel-copper alloy porous film coated on its surface is as follows:

[0047] 1) Dry-mix elemental Ni powder, elemental Si powder, and elemental powders of any one or more elements selected from Ce, Fe, Mn, Cu, and Co at a mass ratio of 60–90:8–25:0.5–10 (preferably 70–85:11–20:2–8, more preferably 77–83:13–17:3–7), with a ball-to-material ratio of 5–15:1 (preferably 8–12:1), and a dry-mixing time of 12–48 h (preferably). After mixing for 20-30 hours, the mixture is placed in a CO or H2 reducing atmosphere at 300-500℃ (preferably 350-450℃) for 1-3 hours (preferably 1.5-2.5 hours), and polyvinyl butyral and alcohol are added. The mixture is then dried and pressed into a plate-shaped or tubular core layer green body. The core layer green body is then sintered at 700-900℃ (preferably 750-850℃) for 2-4 hours (preferably 2-3 hours) to obtain the core layer raw material.

[0048] 1a) The obtained core layer is purged with high-pressure gas and placed in a CO or H2 atmosphere, and reduced at 300-500°C (preferably 350-450°C) for 1-3 hours (preferably 1.5-2.5 hours).

[0049] 2) Mix elemental Ni powder, elemental Cu powder, and elemental powders of any one or more elements selected from Fe, Mn, and Co, PVB, silica sol, and alcohol at a mass ratio of 20–40:5–15:2–8:2–8:10–20:30–50 (preferably 25–35:7–13:4–6:3–7:13–17:35–45) to obtain a slurry to be coated. Immerse the core layer raw material obtained in step 1) in a reaction vessel containing the slurry, pull it up 1–8 times (preferably 3–5 times), dry it, and sinter it at 600–1000℃ (preferably 700–900℃) for 2–4 hours (preferably 2–3 hours) to obtain a dust removal and decarbonization bifunctional catalyst.

[0050] Compared with the prior art, the present invention has the following beneficial effects:

[0051] 1. The present invention provides a method for purifying multi-pollutant industrial flue gas, which is based on a nickel-silicon-based intermetallic compound porous material with a nickel-copper alloy porous membrane on its surface. This method achieves efficient dust interception at the source of flue gas treatment, realizes simultaneous dust removal and decarbonization, avoids the heat loss in the flue gas transportation process of the single-function combined process of dust removal first and then decarbonization, and improves the heat utilization rate.

[0052] It avoids the poisoning of subsequent catalysts by dust, improves the efficiency of subsequent denitrification and desulfurization, and has the ability to resist high temperature, acid, alkali and water corrosion, and can work stably in complex industrial flue gas atmospheres in many fields.

[0053] 2. The present invention provides a multi-pollutant industrial flue gas purification method, which achieves one-step temperature regulation and one-step heat collection of flue gas by regulating the temperature of flue gas and utilizing the waste heat of flue gas after denitrification. This greatly avoids the problem of low heat utilization efficiency caused by "heating and then cooling" or "cooling and then heating" in traditional flue gas purification processes.

[0054] 3. The present invention provides a multi-pollutant industrial flue gas purification method, which achieves good matching of flue gas temperature with each functional unit throughout the process by adjusting the flue gas temperature, high-temperature dust removal and decarbonization, high-temperature denitrification, waste heat utilization and desulfurization. The process flow design is reasonable and the synergy of different functional units is high. Attached Figure Description

[0055] Figure 1 This is a schematic diagram of a multi-pollutant industrial flue gas purification system provided by the present invention.

[0056] Figure labels: 1: Temperature control device; 2: Dust removal and decarbonization device; 3: Denitrification device; 4: Desulfurization device; 5: Waste heat utilization device. Detailed Implementation

[0057] The technical solution of the present invention will be illustrated below with examples. The scope of protection sought by the present invention includes, but is not limited to, the following embodiments.

[0058] According to a first embodiment of the present invention, a method for purifying multi-pollutant industrial flue gas is provided.

[0059] A method for purifying multi-pollutant industrial flue gas, the method comprising the following steps:

[0060] 1) Monitor the temperature of the raw flue gas in real time and adjust the raw flue gas to the set decarbonization temperature;

[0061] 2) The original flue gas after temperature adjustment is subjected to dust removal and decarbonization treatment at the same time to obtain decarbonized flue gas;

[0062] 3) The decarbonized flue gas is then subjected to denitrification treatment to obtain denitrified flue gas;

[0063] 4) After cooling the denitrification flue gas, desulfurization treatment is carried out to obtain clean flue gas.

[0064] Preferably, the method further includes: 5) recycling the heat released during the cooling process of the denitrification flue gas to step 1) as a heat source for adjusting the temperature of the original flue gas or as a heat source for supplementing the heat of the clean flue gas.

[0065] Preferably, in step 1), the raw flue gas includes nitrogen oxides, sulfur dioxide, carbon monoxide, and dust.

[0066] In step 1), the decarburization temperature is 250–400°C, preferably 300–350°C;

[0067] Preferably, adjusting the raw flue gas to the set decarbonization temperature specifically includes:

[0068] (a1) When the original flue gas temperature T < 250℃, preferably T < 300℃, the flue gas temperature is too low. The heat released during the cooling process of the denitrified flue gas or additional heat is introduced to raise the flue gas temperature to above 250℃, preferably above 300℃.

[0069] (a2) When the original flue gas temperature T>400℃, preferably T>350℃, the flue gas temperature is too high. The flue gas temperature is reduced to below 400℃, preferably below 350℃. Preferably, the heat of the flue gas is recycled to supplement the heat of the clean flue gas.

[0070] Preferably, in step 1), the dust removal and decarbonization treatment specifically involves using a nickel-silicon-based intermetallic compound porous material with a nickel-copper alloy porous membrane coated on its surface as a catalyst bed to simultaneously filter out dust and oxidize and remove CO.

[0071] Preferably, the pore size of the nickel-copper alloy porous membrane is 3-5 μm and the membrane thickness is 0.3-0.8 mm.

[0072] Preferably, the nickel-silicon-based metal compound porous material has a tubular structure with a pore size of 30–50 μm and a wall thickness of 5–8 mm.

[0073] Preferably, the nickel-silicon-based intermetallic compound includes Ni, Si, and optionally includes or excludes one or more elements selected from Ce, Fe, Mn, Cu, and Co; preferably, the ratio of the mass of Ni, Si, and the sum of the masses of other elements is 70–85:11–20:2–8, and more preferably 77–83:13–17:3–7.

[0074] Preferably, the nickel-copper alloy porous membrane includes Ni, Cu, and optionally includes or excludes one or more elements selected from Fe, Mn, and Co; preferably, the ratio of the mass of Ni, Cu, and the sum of the masses of other elements is 20-40:5-15:2-8, and more preferably 25-35:7-13:4-6.

[0075] Preferably, the nickel-silicon-based metal compound porous material with a nickel-copper alloy porous film on its surface is obtained by first obtaining the nickel-silicon-based metal compound porous material by powder sintering, and then coating the surface of the nickel-copper-containing slurry onto the surface of the nickel-silicon-based metal compound porous material and then performing a sintering treatment again.

[0076] Preferably, after obtaining the nickel-silicon-based metal compound porous material, it is first pre-reduced before the coating step.

[0077] Preferably, the method further includes: A) pre-oxidizing and calcining the nickel-silicon-based metal compound porous material with a nickel-copper alloy porous film on its surface before use.

[0078] Preferably, the pre-oxidation is carried out in oxygen-containing gas for 0.2 to 4 hours, more preferably 0.5 to 2 hours.

[0079] Preferably, the calcination temperature is 400–800°C, and more preferably 500–700°C.

[0080] Preferably, the calcination time is 2 to 4 hours, and more preferably 2.5 to 3.5 hours.

[0081] Preferably, the denitrification in step 3) is SCR denitrification.

[0082] Preferably, the cooling in step 4) is to cool the denitrification flue gas to 110-140°C, more preferably 120-130°C.

[0083] According to a second embodiment of the present invention, a multi-pollutant industrial flue gas purification system is provided.

[0084] The system includes a temperature control device 1, a dust removal and decarbonization device 2, a denitrification device 3, and a desulfurization device 4 connected in series. The dust removal and decarbonization device 2 is a nickel-silicon-based intermetallic compound porous material with a nickel-copper alloy porous film coated on its surface.

[0085] Preferably, the system further includes a waste heat recovery device 5. The waste heat recovery device 5 is connected to the heating unit of the temperature control device 1 and / or the flue gas outlet of the desulfurization device 4.

[0086] Preparation Example 1

[0087] 1) Dry mix 79g Ni powder and 14g Si powder for 25h. The ball-to-powder ratio of the dry mix is ​​10:1. After mixing, place it in a CO reducing atmosphere at 400℃ for 2h. Then add 5g polyvinyl butyral and 15g alcohol. After drying, press it into a plate-shaped core layer green body. Sinter the core layer green body at 800℃ for 2h to obtain the core layer raw material.

[0088] 1a) The obtained core layer material was surface-purged with high-pressure N2 and then reduced in a CO atmosphere at 400°C for 2 hours.

[0089] 2) Mix 29g Ni powder, 9g Cu powder, 5g PVB, 15g silica sol and 40g alcohol. After mixing, a slurry to be coated is obtained. Immerse the core layer material obtained in step 1) in a reaction vessel containing the slurry, lift it 5 times, dry it and sinter it at 800℃ for 2 hours to obtain a dust removal and decarbonization bifunctional catalyst.

[0090] Preparation Example 2

[0091] 1) Dry mix 79g Ni powder, 14g Si powder and 5g Ce powder for 25h. The ball-to-material ratio of the dry mix is ​​10:1. After mixing, place it in a CO reducing atmosphere at 400℃ for 2h. Then add 8g polyvinyl butyral and 24g alcohol. After drying, press it into a plate-shaped core layer green body. Sinter the core layer green body at 800℃ for 3h to obtain the core layer raw material.

[0092] 1a) The obtained core layer material was surface-purged with high-pressure N2 and then reduced in a CO atmosphere at 400°C for 2 hours.

[0093] 2) Mix 29g Ni powder, 9g Cu powder, 3g Co powder, 5g PVB, 15g silica sol and 40g alcohol. After mixing, a slurry to be coated is obtained. Immerse the core layer raw material obtained in step 1) in a reaction vessel containing the slurry, lift it 5 times, dry it and sinter it at 800℃ for 2 hours to obtain a dust removal and decarbonization bifunctional catalyst.

[0094] Preparation Example 3

[0095] 1) Dry mix 79g Ni powder, 14g Si powder, 2.5g Ce powder and 2.5g Fe powder for 25h. The ball-to-material ratio of the dry mix is ​​10:1. After mixing, place it in a CO reducing atmosphere at 400℃ for 2h. Then add 10g polyvinyl butyral and 30g alcohol. After drying, press it into a plate-shaped core layer green body. Sinter the core layer green body at 800℃ for 2h to obtain the core layer raw material.

[0096] 1a) The obtained core layer material was surface-purged with high-pressure N2 and then reduced in a CO atmosphere at 400°C for 2 hours.

[0097] 2) Mix 29g Ni powder, 9g Cu powder, 1.2g Co powder, 1.2g Mn powder, 5g PVB, 15g silica sol, and 40g alcohol. After mixing, a slurry to be coated is obtained. Immerse the core layer material obtained in step 1) in a reaction vessel containing the slurry, lift it 5 times, dry it, and sinter it at 800℃ for 2 hours to obtain a dual-function catalyst for dust removal and decarbonization.

[0098] The catalysts prepared in Examples 1-3 were used for flue gas purification.

[0099] Example 1

[0100] A) The catalyst prepared in Example 1 was pre-oxidized in air for 1 hour and then calcined at 600°C for 2 hours.

[0101] 1) The temperature of the raw flue gas was monitored as 165℃, and it was adjusted to 320℃.

[0102] 2) The temperature-adjusted raw flue gas is subjected to dust removal and decarbonization using the catalyst pretreated in step A) to obtain decarbonized flue gas.

[0103] 3) Perform SCR denitrification on the decarbonized flue gas to obtain denitrified flue gas.

[0104] 4) Cool the denitrification flue gas to 120℃ and perform activated carbon desulfurization to obtain clean flue gas.

[0105] 5) The heat released during the cooling process of the denitrification flue gas is recycled to step 1) as a heat source for adjusting the temperature of the original flue gas.

[0106] Using the same method as in Example 1, the catalyst used, the pre-oxidation time, calcination temperature and calcination time in step A), and the flue gas adjustment temperature in step 1) were adjusted to conduct parallel experiments. The specific parameters are shown in the table below.

[0107]

[0108]

[0109] Comparative Example 1

[0110] 1) Dry mix 80g of Ni powder for 25h, with a ball-to-material ratio of 10:1. After mixing, place it in a CO reducing atmosphere at 400℃ for 2h. Then add 4g of polyvinyl butyral and 12g of alcohol. After drying, press it into a plate-shaped core layer green body. Sinter the core layer green body at 800℃ for 2h to obtain the core layer raw material.

[0111] 1a) The obtained core layer material was surface-purged with high-pressure N2 and then reduced in a CO atmosphere at 400°C for 2 hours.

[0112] 2) Mix 31g Ni powder, 11g Cu powder, 2.5g Co powder, 5g PVB, 15g silica sol and 40g alcohol. After mixing, a slurry to be coated is obtained. Immerse the core layer raw material obtained in step 1) in a reaction vessel containing the slurry, lift it 5 times, dry it and sinter it at 800℃ for 2 hours to obtain a dust removal and decarbonization bifunctional catalyst.

[0113] Comparative Example 2

[0114] 1) Dry mix 15g of Si powder for 25h, with a ball-to-material ratio of 10:1. After mixing, place it in a CO reducing atmosphere at 400℃ for 2h. Then add 0.75g of polyvinyl butyral and 1.8g of alcohol. After drying, press it into a plate-shaped core layer green body. Sinter the core layer green body at 800℃ for 2h to obtain the core layer raw material.

[0115] 1a) The obtained core layer material was surface-purged with high-pressure N2 and then reduced in a CO atmosphere at 400°C for 2 hours.

[0116] 2) Mix 31g Ni powder, 11g Cu powder, 2.5g Co powder, 5g PVB, 15g silica sol and 40g alcohol. After mixing, a slurry to be coated is obtained. Immerse the core layer raw material obtained in step 1) in a reaction vessel containing the slurry, lift it 5 times, dry it and sinter it at 800℃ for 2 hours to obtain a dust removal and decarbonization bifunctional catalyst.

[0117] Comparative Example 3

[0118] 1) Dry mix 80g Ni powder, 15g Si powder, 2.5g Ce powder and 2.5g Fe powder for 25h. The ball-to-powder ratio of the dry mix is ​​10:1. After mixing, place it in a CO reducing atmosphere at 400℃ for 2h. Then add 6g polyvinyl butyral and 18g alcohol. After drying, press it into a plate-shaped core layer green body. Sinter the core layer green body at 800℃ for 2h to obtain the core layer raw material.

[0119] 1a) The obtained core layer material was surface-purged with high-pressure N2 and then reduced in a CO atmosphere at 400°C for 2 hours.

[0120] 2) Mix 31g Ni powder, 5g PVB, 15g silica sol and 40g alcohol. After mixing, a slurry to be coated is obtained. Immerse the core layer raw material obtained in step 1) in a reaction vessel containing the slurry, lift it 5 times, dry it and sinter it at 800℃ for 2 hours to obtain a dust removal and decarbonization bifunctional catalyst.

[0121] Comparative Example 4

[0122] 1) Dry mix 80g Ni powder, 15g Si powder, 2.5g Ce powder and 2.5g Fe powder for 25h. The ball-to-powder ratio of the dry mix is ​​10:1. After mixing, place it in a CO reducing atmosphere at 400℃ for 2h. Then add 9g polyvinyl butyral and 27g alcohol. After drying, press it into a plate-shaped core layer green body. Sinter the core layer green body at 800℃ for 2.5h to obtain the core layer raw material.

[0123] 1a) The obtained core layer material was surface-purged with high-pressure N2 and then reduced in a CO atmosphere at 400°C for 2 hours.

[0124] 2) Mix 11g Cu powder, 5g PVB, 15g silica sol and 40g alcohol. After mixing, a slurry to be coated is obtained. Immerse the core layer material obtained in step 1) in a reaction vessel containing the slurry, lift it 5 times, dry it and sinter it at 800℃ for 2 hours to obtain a dust removal and decarbonization bifunctional catalyst.

[0125] Comparative Example 5

[0126] A) The catalyst prepared in Comparative Example 1 was pre-oxidized in air for 0.5 h and then calcined at 600 °C for 2 h.

[0127] 1) The temperature of the raw flue gas was monitored as 165℃, and it was adjusted to 320℃.

[0128] 2) The temperature-adjusted raw flue gas is subjected to dust removal and decarbonization using the catalyst pretreated in step A) to obtain decarbonized flue gas.

[0129] 3) Perform SCR denitrification on the decarbonized flue gas to obtain denitrified flue gas.

[0130] 4) Cool the denitrification flue gas to 120℃ and perform activated carbon desulfurization to obtain clean flue gas.

[0131] 5) The heat released during the cooling process of the denitrification flue gas is recycled to step 1) as a heat source for adjusting the temperature of the original flue gas.

[0132] Comparative Example 6

[0133] A) The catalyst prepared in Comparative Example 2 was pre-oxidized in air for 0.5 h and then calcined at 600 °C for 2 h.

[0134] 1) The temperature of the raw flue gas was monitored as 163℃, and it was adjusted to 320℃.

[0135] 2) The temperature-adjusted raw flue gas is subjected to dust removal and decarbonization using the catalyst pretreated in step A) to obtain decarbonized flue gas.

[0136] 3) Perform SCR denitrification on the decarbonized flue gas to obtain denitrified flue gas.

[0137] 4) Cool the denitrification flue gas to 120℃ and perform activated carbon desulfurization to obtain clean flue gas.

[0138] 5) The heat released during the cooling process of the denitrification flue gas is recycled to step 1) as a heat source for adjusting the temperature of the original flue gas.

[0139] Comparative Example 7

[0140] A) The catalyst prepared in Comparative Example 3 was pre-oxidized in air for 1 hour and then calcined at 600°C for 2 hours.

[0141] 1) The temperature of the raw flue gas was monitored as 164℃, and it was adjusted to 320℃.

[0142] 2) The temperature-adjusted raw flue gas is subjected to dust removal and decarbonization using the catalyst pretreated in step A) to obtain decarbonized flue gas.

[0143] 3) Perform SCR denitrification on the decarbonized flue gas to obtain denitrified flue gas.

[0144] 4) Cool the denitrification flue gas to 120℃ and perform activated carbon desulfurization to obtain clean flue gas.

[0145] 5) The heat released during the cooling process of the denitrification flue gas is recycled to step 1) as a heat source for adjusting the temperature of the original flue gas.

[0146] Comparative Example 8

[0147] A) The catalyst prepared in Comparative Example 4 was pre-oxidized in air for 0.5 h and then calcined at 600 °C for 2 h.

[0148] 1) The temperature of the raw flue gas was monitored as 169℃, and it was adjusted to 320℃.

[0149] 2) The temperature-adjusted raw flue gas is subjected to dust removal and decarbonization using the catalyst pretreated in step A) to obtain decarbonized flue gas.

[0150] 3) Perform SCR denitrification on the decarbonized flue gas to obtain denitrified flue gas.

[0151] 4) Cool the denitrification flue gas to 120℃ and perform activated carbon desulfurization to obtain clean flue gas.

[0152] 5) The heat released during the cooling process of the denitrification flue gas is recycled to step 1) as a heat source for adjusting the temperature of the original flue gas.

[0153] Comparative Example 9

[0154] A) The catalyst prepared in Comparative Example 4 was pre-oxidized in air for 1 hour and then calcined at 600°C for 3 hours.

[0155] 1) The temperature of the raw flue gas was monitored as 168℃, and it was adjusted to 320℃.

[0156] 2) After the temperature-adjusted raw flue gas is dusted by a bag filter, it is then decarbonized by the catalyst pretreated in step A) to obtain decarbonized flue gas.

[0157] 3) Perform SCR denitrification on the decarbonized flue gas to obtain denitrified flue gas.

[0158] 4) Cool the denitrification flue gas to 120℃ and perform activated carbon desulfurization to obtain clean flue gas.

[0159] 5) The heat released during the cooling process of the denitrification flue gas is recycled to step 1) as a heat source for adjusting the temperature of the original flue gas.

[0160] The flue gas purified in Examples 1-28 and Comparative Examples 5-9 was tested to obtain the corresponding dust removal rate, decarbonization rate, denitrification rate and desulfurization rate. The results are shown in Table 2.

[0161]

[0162]

[0163] Based on the above experimental results, nickel-silicon based intermetallic compound porous materials with nickel-copper alloy porous films on their surfaces can achieve efficient dust interception at the source of flue gas treatment, realize simultaneous dust removal and decarbonization, and have high temperature resistance and corrosion resistance, which can effectively avoid the impact of pollutants in flue gas on catalysts in subsequent processes.

Claims

1. A method for purifying multi-pollutant industrial flue gas, characterized in that: The method includes the following steps: 1) Monitor the temperature of the raw flue gas in real time and adjust the raw flue gas to the set decarbonization temperature; 2) The original flue gas after temperature adjustment is subjected to dust removal and decarbonization treatment simultaneously to obtain decarbonized flue gas; the dust removal and decarbonization treatment specifically involves using a nickel-silicon-based intermetallic compound porous material with a nickel-copper alloy porous membrane as a catalytic bed to simultaneously filter dust and oxidize and remove CO; the nickel-silicon-based intermetallic compound includes Ni, Si, and optionally includes one or more elements selected from Ce, Fe, Mn, Cu, and Co; the mass ratio of Ni, Si and the sum of other elements is 70~85:11~20:2~8; The nickel-copper alloy porous membrane includes Ni, Cu, and optionally one or more elements selected from Fe, Mn, and Co; the mass ratio of Ni, Cu, and the sum of other elements is 20~40:5~15:2~8; the nickel-silicon-based intermetallic porous material coated with the nickel-copper alloy porous membrane is obtained by first obtaining the nickel-silicon-based intermetallic porous material by powder sintering, performing pre-reduction, and then coating the surface of the nickel-copper-containing slurry onto the surface of the nickel-silicon-based intermetallic porous material and performing sintering again. 3) The decarbonized flue gas is then subjected to denitrification treatment to obtain denitrified flue gas; 4) After cooling the denitrification flue gas, desulfurization treatment is carried out to obtain clean flue gas.

2. The method according to claim 1, characterized in that: The method also includes: 5) recycling the heat released during the cooling process of the denitrification flue gas to step 1) as a heat source for adjusting the temperature of the original flue gas or as a heat source for supplementing the heat of the clean flue gas.

3. The method according to claim 1 or 2, characterized in that: In step 1), the raw flue gas includes nitrogen oxides, sulfur dioxide, carbon monoxide, and dust; and / or In step 1), the decarburization temperature is 250~400℃.

4. The method according to claim 3, characterized in that: In step 1), the decarburization temperature is 300~350℃.

5. The method according to claim 3, characterized in that: The adjustment of the raw flue gas to the set decarbonization temperature specifically includes: (a1) When the original flue gas temperature T < 250℃, the flue gas temperature is too low. The heat released during the cooling process of the denitrification flue gas or additional heat is introduced to raise the flue gas temperature to above 250℃. (a2) When the original flue gas temperature T>400℃, the flue gas temperature is too high, so reduce the flue gas temperature to below 400℃.

6. The method according to claim 4, characterized in that: The adjustment of the raw flue gas to the set decarbonization temperature specifically includes: (a1) When the original flue gas temperature T < 300℃, the flue gas temperature is too low. The heat released during the cooling process of the denitrified flue gas or additional heat is introduced to raise the flue gas temperature to above 300℃. (a2) When the original flue gas temperature T>350℃, the flue gas temperature is too high, so the flue gas temperature is reduced to below 350℃.

7. The method according to claim 5 or 6, characterized in that: The heat from the flue gas is recycled to reheat the clean flue gas.

8. The method according to claim 1 or 2, characterized in that: The pore size of the nickel-copper alloy porous membrane is 3~5μm, and the membrane thickness is 0.3~0.8mm; and / or The nickel-silicon-based intermetallic compound porous material has a tubular structure with a pore size of 30-50 μm and a wall thickness of 5-8 mm.

9. The method according to claim 1, characterized in that: The mass ratio of Ni, Si, and the sum of other elements is 77~83:13~17:3~7; and / or The ratio of the mass of Ni, Cu and the sum of the masses of other elements is 25~35:7~13:4~6.

10. The method according to claim 1 or 2, characterized in that: The method further includes: A) Pre-oxidizing and calcining the nickel-silicon-based intermetallic compound porous material with a nickel-copper alloy porous film on its surface before use.

11. The method according to claim 10, characterized in that: The pre-oxidation is performed by placing the sample in an oxygen-containing gas for 0.2–4 hours; and / or The calcination temperature is 400~800℃; and / or The calcination time is 2-4 hours.

12. The method according to claim 11, characterized in that: The pre-oxidation is performed by placing the sample in an oxygen-containing gas for 0.5–2 hours; and / or The calcination temperature is 500~700℃; and / or The calcination time is 2.5~3.5h.

13. The method according to any one of claims 1-2, 4-6, 9, 11-12, characterized in that: Step 3) refers to SCR denitrification; and / or Step 4) cooling refers to cooling the denitrification flue gas to 110~140℃; and / or Step 4) describes desulfurization using activated carbon.

14. The method according to claim 13, characterized in that: Step 4) involves cooling the denitrification flue gas to 120~130℃.

15. A system used in the method according to any one of claims 1-14, characterized in that: The system includes a temperature control device (1), a dust removal and decarbonization device (2), a denitrification device (3), and a desulfurization device (4) connected in series; wherein the dust removal and decarbonization device (2) is a nickel-silicon-based intermetallic compound porous material with a nickel-copper alloy porous film on its surface.

16. The system according to claim 15, characterized in that: The system also includes a waste heat utilization device (5); the waste heat utilization device (5) is connected to the heating unit of the temperature control device (1) and / or the flue gas outlet of the desulfurization device (4).

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