Catalytic flue gas treatment device

Abstract

This invention discloses a catalytic flue gas treatment device that solves the technical problem of secondary pollution caused by sulfur dioxide generated during the catalytic oxidation of H2S. It includes: a reaction system for removing H2S from the flue gas to be treated, comprising at least one reactor, the reactor having an inlet, an outlet, a liquid outlet, and a catalyst located within the reactor; a regenerated liquid spraying device for washing and regenerating the catalyst is installed on the reactor; during operation, the flue gas to be treated enters the reactor through the inlet, passes through the catalyst, and then exits from the outlet as treated flue gas; the H2S in the flue gas reacts on the catalyst to form elemental sulfur and sulfuric acid, the sulfuric acid being generated by further catalytic oxidation of sulfur dioxide produced by the reaction of elemental sulfur with oxygen and then reacting with water; a regenerated liquid circulation system; and a flue gas conveying system.

Description

Technical Field

[0001] This invention relates to the field of catalytic flue gas treatment technology, specifically to methods and equipment for dephosphorization and desulfurization of yellow phosphorus tail gas, and catalytic flue gas treatment devices. Background Technology

[0002] To remove sulfur dioxide from flue gas, the applicant has developed catalytic flue gas treatment technology. For example, the applicant discloses catalytic flue gas desulfurization equipment in patent documents with publication numbers CN214764545U, CN114653202A, and CN114797450A. However, their applications are limited to sulfur dioxide removal.

[0003] On the other hand, yellow phosphorus tail gas is a process gas mainly containing carbon monoxide discharged after the phosphorus collection process in the electric furnace yellow phosphorus production process. Besides CO, this gas typically contains impurities such as P4, CO2, PH3, O2, COS, CS2, H2S, water vapor, and HF. Currently, the main purification methods for yellow phosphorus tail gas include:

[0004] 1) Water washing method: Introducing the yellow phosphorus tail gas into a water washing tower can remove most of the dust, fluorides, phosphorides, and sulfides;

[0005] 2) Alkaline washing method: The yellow phosphorus tail gas is introduced into the alkaline washing tower and washed with NaOH solution, which can remove a large amount of acidic gases such as H2S and CO2 from the tail gas.

[0006] 3) Temperature-switched adsorption (TSA) method: This method uses temperature changes to control the adsorption and desorption processes. It involves adsorption at low temperatures and desorption and regeneration at high temperatures, and is mainly used for dephosphorization.

[0007] 4) Pressure Swing Adsorption (PSA): This method uses pressure changes to control the adsorption and desorption processes. It involves high-pressure adsorption and low-pressure desorption and regeneration, and is mainly used to remove H2S and CO2 from yellow phosphorus tail gas.

[0008] 5) DePOx continuous catalytic oxidation dephosphorization process: a continuous treatment process that uses selective catalysts to oxidize PH3 in yellow phosphorus tail gas into elemental phosphorus and water under conditions of 200-300℃ and near atmospheric pressure by precisely controlling the amount of oxygen.

[0009] 6) For phosphine and hydrogen sulfide in yellow phosphorus tail gas, there are also ferric chloride method, sodium hypochlorite oxidation method, concentrated sulfuric acid absorption method, and hydrogen peroxide oxidation method. These all use chemical oxidants (FeCl3, NaClO, H2SO4, H2O2) to oxidize PH3 and H2S into harmless or easily treatable products, and therefore can be collectively referred to as chemical oxidant oxidation methods.

[0010] Currently, most manufacturers use a combination of water washing and alkaline washing processes. A small number of manufacturers, in addition to water washing and alkaline washing, also add temperature swing adsorption (TSA), pressure swing adsorption (PSA), DePOx continuous catalytic oxidation dephosphorization process, and chemical oxidant oxidation process as needed. Summary of the Invention

[0011] The purpose of this invention is to provide a novel method and equipment for dephosphorization and desulfurization of yellow phosphorus tail gas, so as to solve the technical problem of efficient removal of phosphorus-containing and sulfur-containing pollutants from yellow phosphorus tail gas.

[0012] In addition, another objective of the present invention is to provide a catalytic flue gas treatment device that can be used in, but is not limited to, the above-mentioned yellow phosphorus tail gas dephosphorization and desulfurization methods and equipment, to solve the technical problem of secondary pollution caused by sulfur dioxide generated during the catalytic oxidation of H2S.

[0013] In one aspect, a method for dephosphorizing and desulfurizing yellow phosphorus tail gas is provided, comprising: passing the yellow phosphorus tail gas into a dephosphorization device to remove phosphorus-containing substances from the yellow phosphorus tail gas, wherein the dephosphorization device adopts a first catalytic flue gas treatment device, the first catalytic flue gas treatment device includes a first reactor, during operation, the yellow phosphorus tail gas enters the first reactor from the inlet of the first reactor, passes through a first catalyst, and is discharged from the exhaust port of the first reactor as dephosphorized flue gas, wherein PH3 and P4 in the yellow phosphorus tail gas react on the first catalyst to form phosphorus oxides and phosphoric acid when passing through the first catalyst, and during the washing and regeneration of the first catalyst, the phosphorus oxides and phosphoric acid enter the regeneration liquid sprayed on the first catalyst and are discharged from the drain port of the first reactor; passing the dephosphorized flue gas into an organic sulfur hydrolysis conversion device to convert the organic sulfur in the dephosphorized flue gas into H2S, wherein the organic sulfur hydrolysis conversion device adopts a second catalytic flue gas treatment device, the second catalytic flue gas treatment device includes a second reactor, during operation, the dephosphorized flue gas enters from the inlet of the second reactor. The flue gas enters the second reactor, passes through the second catalyst, and is then discharged from the exhaust port of the second reactor as organic sulfur hydrolysis conversion flue gas. The organic sulfur in the dephosphorized flue gas is hydrolyzed into H2S when passing through the second catalyst. The organic sulfur hydrolysis conversion flue gas is then passed into a desulfurization device to remove the H2S. The desulfurization device adopts a third catalytic flue gas treatment device, which includes a third reactor. During operation, the organic sulfur hydrolysis conversion flue gas enters the third reactor from the inlet, passes through the third catalyst, and is then discharged from the exhaust port of the third reactor as desulfurized flue gas. The H2S in the organic sulfur hydrolysis conversion flue gas reacts on the third catalyst to form elemental sulfur and sulfuric acid. The sulfuric acid is generated by further catalytic oxidation of sulfur dioxide produced by the reaction of elemental sulfur with oxygen and then reacting with water. When the third catalyst is washed and regenerated, the elemental sulfur and the sulfuric acid enter the regeneration liquid sprayed on the third catalyst and are then discharged from the drain port of the third reactor.

[0014] Secondly, the yellow phosphorus tail gas dephosphorization and desulfurization equipment includes: a dephosphorization device for receiving yellow phosphorus tail gas and removing phosphorus-containing substances from it, wherein the dephosphorization device employs a first catalytic flue gas treatment device, which includes a first reactor. During operation, the yellow phosphorus tail gas enters the first reactor through the inlet, passes through a first catalyst, and is then discharged from the exhaust port of the first reactor as dephosphorized flue gas. PH3 and P4 in the yellow phosphorus tail gas react on the first catalyst to form phosphorus oxides and phosphoric acid. During the washing and regeneration of the first catalyst, the phosphorus oxides and phosphoric acid enter the regeneration liquid sprayed onto the first catalyst and are discharged from the drain port of the first reactor; and an organic sulfur hydrolysis conversion device for receiving the dephosphorized flue gas and converting the organic sulfur in it into H2S, wherein the organic sulfur hydrolysis conversion device employs a second catalytic flue gas treatment device, which includes a second reactor. During operation, the dephosphorized flue gas enters from the inlet of the second reactor. The second reactor then passes through the second catalyst and is discharged from the exhaust port of the second reactor as organic sulfur hydrolysis conversion flue gas. The organic sulfur in the dephosphorized flue gas is hydrolyzed into H2S when passing through the second catalyst. A desulfurization device is used to receive the organic sulfur hydrolysis conversion flue gas and remove H2S from it. The desulfurization device adopts a third catalytic flue gas treatment device, which includes a third reactor. During operation, the organic sulfur hydrolysis conversion flue gas enters the third reactor from the inlet, passes through the third catalyst, and is discharged from the exhaust port of the third reactor as desulfurized flue gas. The H2S in the organic sulfur hydrolysis conversion flue gas reacts on the third catalyst to form elemental sulfur and sulfuric acid. The sulfuric acid is generated by further catalytic oxidation of sulfur dioxide produced by the reaction of elemental sulfur with oxygen and then reacting with water. When the third catalyst is washed and regenerated, the elemental sulfur and the sulfuric acid enter the regeneration liquid sprayed on the third catalyst and are discharged from the drain port of the third reactor.

[0015] The aforementioned method and equipment for dephosphorizing and desulfurizing yellow phosphorus tail gas employs a three-stage catalytic flue gas treatment: the first stage converts PH3 and P4 into controllable phosphorus oxides and phosphoric acid through catalytic oxidation; the second stage converts organic sulfur (such as COS and CS2) into H2S through catalytic hydrolysis; and the third stage catalytically oxidizes H2S into elemental sulfur. The entire treatment process, through the selective reaction of the catalyst, achieves efficient and continuous treatment of phosphorus- and sulfur-containing pollutants in the yellow phosphorus tail gas. Furthermore, addressing the issue of elemental sulfur being easily oxidized to sulfur dioxide, thus causing secondary pollution, the third catalyst further catalytically oxidizes sulfur dioxide and reacts it with water to form sulfuric acid, thereby avoiding sulfur dioxide emissions.

[0016] More specifically, the three-stage catalytic flue gas treatment described above exhibits the following coupling effects: First, phosphides (especially PH3 and P4) are inherently toxic and can poison subsequent catalysts (PH3 and P4 phosphides possess strong reducing and coordination properties; when they come into contact with the catalyst surface, they readily undergo chemical adsorption and reaction with the catalyst's active sites, thereby occupying or covering these sites). Therefore, preferentially removing phosphides effectively protects the activity and lifespan of the subsequent second and third catalysts. Second, organic sulfur is uniformly converted to H2S through the second-stage catalytic hydrolysis. Compared to organic sulfur compounds such as COS and CS2, H2S is more easily catalytically oxidized, significantly improving the desulfurization efficiency of the third stage. Finally, the temperature gradient and chemical reaction characteristics of the entire treatment chain create a good synergistic effect.

[0017] Thirdly, a catalytic flue gas treatment device is provided, comprising: a reaction system for reacting and removing H2S from the flue gas to be treated, including at least one reactor, the reactor having an inlet, an outlet, a drain outlet, and a catalyst located in the reactor, the reactor being equipped with a regeneration liquid spraying device for washing and regenerating the catalyst; during operation, the flue gas to be treated enters the reactor through the inlet, passes through the catalyst, and then exits from the outlet as treated flue gas; the H2S in the flue gas reacts on the catalyst to form elemental sulfur and sulfuric acid, the sulfuric acid being generated by further catalytic oxidation of sulfur dioxide produced by the reaction of elemental sulfur with oxygen and then reacting with water; during the washing and regeneration of the catalyst, the elemental sulfur and the sulfuric acid enter the regeneration liquid sprayed on the catalyst and are then discharged from the outlet of the reactor; regeneration A liquid circulation system includes at least one regenerated liquid tank and a regenerated liquid circulation control network connecting the at least one regenerated liquid tank and each reactor. The regenerated liquid circulation control network has an output-side control network, an input-side control network, and a regenerated liquid driving device. The output-side control network can guide the regenerated liquid in the selected regenerated liquid tank to the regenerated liquid spraying device of the selected reactor. The input-side control network can guide the regenerated liquid output from the drain port of the selected reactor to the selected regenerated liquid tank. The regenerated liquid driving device can provide the required power to the regenerated liquid. A flue gas conveying system includes an inlet network and an exhaust network. The inlet network includes an inlet main pipe and inlet branch pipes that connect the inlet main pipe to the inlet ports of each reactor. Each inlet branch pipe has an on / off control mechanism. The exhaust network includes an exhaust main pipe and exhaust branch pipes that connect the exhaust main pipe to the exhaust ports of each reactor.

[0018] The aforementioned catalytic flue gas treatment device integrates a reaction system, a regenerated liquid circulation system, and a flue gas conveying system. It uses a catalyst to convert H2S into elemental S. Addressing the issue of elemental S being easily oxidized to sulfur dioxide, causing secondary pollution, the catalyst further catalytically oxidizes sulfur dioxide and reacts it with water to form sulfuric acid, thus avoiding sulfur dioxide emissions. Furthermore, the regenerated liquid circulation system achieves directional transport and recovery of the regenerated liquid through a circulation control pipeline network, offering flexible operation. The inlet and outlet pipe network design of the flue gas conveying system allows multiple reactors to operate in parallel, facilitating maintenance and repair. It can be used in, but is not limited to, the aforementioned methods and equipment for dephosphorization and desulfurization of yellow phosphorus tail gas.

[0019] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Additional aspects and advantages provided by the present 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. Attached Figure Description

[0020] The accompanying drawings, which form part of this specification, are used to aid in understanding the invention. The contents provided in the drawings and their related descriptions in this specification can be used to explain the invention, but do not constitute an undue limitation of the invention.

[0021] Figure 1 This is a schematic diagram of a yellow phosphorus tail gas dephosphorization and desulfurization device according to an embodiment of the present invention.

[0022] Figure 2 for Figure 1 A partial enlarged view of the desulfurization unit.

[0023] Figure 3 for Figure 1 A schematic diagram of the specific structure of the desulfurization unit.

[0024] Figure 4 This is a schematic diagram of a pre-desulfurization device in a yellow phosphorus tail gas dephosphorization and desulfurization equipment according to an embodiment of the present invention. Detailed Implementation

[0025] 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:

[0026] The technical solutions and features provided in the various sections, including the following description, can be combined with each other without conflict. Furthermore, where possible, these technical solutions, features, and related combinations can be given specific technical subject matter and protected by relevant patents.

[0027] The embodiments of the present invention described below are generally only some embodiments and not all embodiments. Based on these embodiments, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of patent protection.

[0028] The terms "comprising," "including," "having," and any variations thereof in this specification, the corresponding claims, and related sections are intended to cover non-exclusive inclusion. Other related terms and units can be reasonably interpreted based on the relevant content provided in this specification.

[0029] Figure 1 This is a schematic diagram of a yellow phosphorus tail gas dephosphorization and desulfurization device according to an embodiment of the present invention. Figure 1 As shown, a dephosphorization and desulfurization device for yellow phosphorus tail gas mainly includes: a dephosphorization device 7, an organic sulfur hydrolysis conversion device 8, and a desulfurization device 9.

[0030] The dephosphorization device 7 is used to receive yellow phosphorus tail gas and remove phosphorus-containing substances from the yellow phosphorus tail gas. The dephosphorization device 7 adopts a first catalytic flue gas treatment device, which includes a first reactor 71. During operation, the yellow phosphorus tail gas enters the first reactor 71 from the inlet, passes through the first catalyst, and is discharged from the exhaust port of the first reactor 71 as dephosphorized flue gas. When the yellow phosphorus tail gas passes through the first catalyst, the PH3 and P4 react on the first catalyst to form phosphorus oxide and phosphoric acid. When the first catalyst is washed and regenerated, the phosphorus oxide and phosphoric acid enter the regeneration liquid sprayed on the first catalyst and are discharged from the drain port of the first reactor 71.

[0031] The organic sulfur hydrolysis conversion device 8 is used to receive the dephosphorized flue gas and convert the organic sulfur in the dephosphorized flue gas into H2S. The organic sulfur hydrolysis conversion device 8 adopts a second catalytic flue gas treatment device. The second catalytic flue gas treatment device includes a second reactor 81. When working, the dephosphorized flue gas enters the second reactor 81 from the inlet, passes through the second catalyst, and is discharged from the exhaust port of the second reactor 81 as organic sulfur hydrolysis conversion flue gas. The organic sulfur in the dephosphorized flue gas is hydrolyzed into H2S when passing through the second catalyst.

[0032] The desulfurization device 9 is used to receive the organic sulfur hydrolysis conversion flue gas and remove H2S from it. The desulfurization device 9 adopts a third catalytic flue gas treatment device, which includes a third reactor 91. During operation, the organic sulfur hydrolysis conversion flue gas enters the third reactor 91 through the inlet, passes through the third catalyst, and is then discharged from the exhaust port of the third reactor 91 as desulfurized flue gas. When the H2S in the organic sulfur hydrolysis conversion flue gas passes through the third catalyst, it reacts on the third catalyst to form elemental sulfur and sulfuric acid. The sulfuric acid is generated by further catalytic oxidation of sulfur dioxide produced by the reaction of elemental sulfur with oxygen and then reacting with water. When the third catalyst is washed and regenerated, the elemental sulfur and the sulfuric acid enter the regeneration liquid sprayed on the third catalyst and are discharged from the outlet of the third reactor 91.

[0033] The aforementioned dephosphorization and desulfurization equipment for yellow phosphorus tail gas employs a three-stage catalytic flue gas treatment method: the first stage converts PH3 and P4 into controllable phosphorus oxides and phosphoric acid through catalytic oxidation; the second stage converts organic sulfur (such as COS and CS2) into H2S through catalytic hydrolysis; and the third stage catalytically oxidizes H2S into elemental sulfur. The entire treatment process, through the selective reaction of the catalyst, achieves efficient and continuous treatment of phosphorus- and sulfur-containing pollutants in the yellow phosphorus tail gas. Furthermore, addressing the issue of elemental sulfur being easily oxidized to sulfur dioxide, thus causing secondary pollution, the third catalyst further catalytically oxidizes sulfur dioxide and reacts it with water to form sulfuric acid, thereby avoiding sulfur dioxide emissions.

[0034] More specifically, the three-stage catalytic flue gas treatment described above exhibits the following coupling effects: First, phosphides (especially PH3 and P4) are inherently toxic and can poison subsequent catalysts (PH3 and P4 phosphides possess strong reducing and coordination properties; when they come into contact with the catalyst surface, they readily undergo chemical adsorption and reaction with the catalyst's active sites, thereby occupying or covering these sites). Therefore, preferentially removing phosphides effectively protects the activity and lifespan of the subsequent second and third catalysts. Second, organic sulfur is uniformly converted to H2S through the second-stage catalytic hydrolysis. Compared to organic sulfur compounds such as COS and CS2, H2S is more easily catalytically oxidized, significantly improving the desulfurization efficiency of the third stage. Finally, the temperature gradient and chemical reaction characteristics of the entire treatment chain create a good synergistic effect.

[0035] like Figure 1As shown, the above-mentioned yellow phosphorus tail gas dephosphorization and desulfurization equipment may further include a scrubbing pretreatment device. The scrubbing pretreatment device is located before the dephosphorization device 7. The scrubbing pretreatment device is used to scrub the yellow phosphorus tail gas before sending it into the dephosphorization device 7. The scrubbing pretreatment device 7 includes a first scrubbing system 1 and / or a second scrubbing system 2. The first scrubbing system 1 is used to perform water scrubbing treatment on the yellow phosphorus tail gas, and the second scrubbing system 2 is used to perform alkaline solution scrubbing treatment on the yellow phosphorus tail gas.

[0036] Specifically, in this embodiment, the rinsing pretreatment 7 includes a first rinsing system 1 and a second rinsing system 2. The first rinsing system 1 includes two-stage first rinsing towers, and the second rinsing system 2 includes a first-stage second rinsing tower. The second rinsing tower is connected in series after the two-stage first rinsing towers.

[0037] The scrubbing pretreatment unit is mainly used to remove large particulate matter and some water-soluble gaseous pollutants from yellow phosphorus tail gas. Water scrubbing can initially remove some phosphorus and sulfur compounds, while alkaline solution scrubbing can further remove acidic gases, thereby reducing the load on subsequent treatments.

[0038] Furthermore, a gas-liquid separation device 3 and a gas heating device are sequentially arranged between the rinsing pretreatment device and the dephosphorization device 7. The function of the gas-liquid separation device 3 is to achieve gas-liquid separation. The separated yellow phosphorus tail gas can first enter the gas distribution cylinder 4, which can divert the yellow phosphorus tail gas as needed. For example, the gas distribution cylinder 4 can divert a portion of the yellow phosphorus tail gas to a gas holder for storage (the yellow phosphorus tail gas in the gas holder can be used for combustion) and divert a portion of the yellow phosphorus tail gas to the gas heating device.

[0039] The gas separator 4 is located after the gas-liquid separator 3 and before the gas heating device. It can divert the yellow phosphorus tail gas according to actual needs, which not only realizes the rational use of resources, but also avoids overloading of subsequent catalytic treatment devices.

[0040] In this embodiment, the gas heating device specifically includes a heat exchanger 5 and a heater 6. The function of the heat exchanger 5 is to preheat the yellow phosphorus tail gas output from the desulfurization device 9 using the yellow phosphorus tail gas output from the gas distribution cylinder 4, and the function of the heater 6 is to further heat the yellow phosphorus tail gas preheated by the heat exchanger 5 using external water vapor.

[0041] The gas heating device adopts a two-stage heating method using heat exchanger 5 and heater 6. This design not only saves energy but also ensures that the yellow phosphorus gas entering the dephosphorization unit 7 reaches the appropriate reaction temperature.

[0042] In summary, the working process of the above-mentioned yellow phosphorus tail gas dephosphorization and desulfurization equipment is as follows: the yellow phosphorus tail gas first undergoes water scrubbing treatment in the first scrubbing system (including two-stage first scrubbing towers) and alkaline solution scrubbing treatment in the second scrubbing system (including a first-stage second scrubbing tower). After being separated by the gas-liquid separation device 3, it enters the gas distribution cylinder 4. The gas distribution cylinder 4 diverts part of the yellow phosphorus tail gas to the gas holder for storage and combustion, while the other part is heated by the heat exchanger 5 (using the yellow phosphorus tail gas output from the desulfurization device 9 for preheating) and the heater 6, and then sequentially enters the dephosphorization device 7 (PH3 and P4 react on the first catalyst to form phosphorus oxide and phosphoric acid), the organic sulfur hydrolysis conversion device 8 (organic sulfur is hydrolyzed into H2S on the second catalyst), and the desulfurization device 9 (H2S reacts on the third catalyst to form elemental S and sulfuric acid), and is finally discharged as desulfurized flue gas.

[0043] It should be noted that the first, second, and third catalytic flue gas treatment devices mentioned above all use catalytic methods to treat flue gas. From the perspective of process principle, they are not entirely new technologies (for example, there is already a technology in the field of natural gas purification that catalytically hydrolyzes organic sulfur into hydrogen sulfide). However, the key lies in the combination method and the selection of appropriate catalysts and operating process parameters based on the combined process.

[0044] In this embodiment, the operating conditions of the first reactor are:

[0045] 1) First catalyst formulation:

[0046] The first catalyst is mainly composed of the following components in parts by weight, uniformly mixed:

[0047] Nano-PdO particles: 0.8-1.2 parts;

[0048] Nano PtO2 particles: 0.4-0.6 parts;

[0049] CeO2: 3.5-4.5 parts;

[0050] V2O5: 2.5-3.5 parts;

[0051] Activated carbon carrier: 90-93 parts;

[0052] The weight ratio of nano-PdO particles to nano-PtO2 particles is (1.8-2):1, and the weight ratio of CeO2 to V2O5 is (1.2-1.5):1.

[0053] 2) Operating parameters of the first reactor: operate at 100-120℃, with a space velocity controlled at 1000-2000 h⁻¹. -1 The O2 concentration in the gas phase is 5-8% (v / v%), and the moisture content is less than 2% (v / v%).

[0054] It can be seen that the first catalyst mainly consists of nano-PdO particles, nano-PtO2 particles, CeO2, V2O5, and an activated carbon support. The weight ratio of nano-PdO to nano-PtO2 is controlled at (1.8-2):1, and the weight ratio of CeO2 to V2O5 is controlled at (1.2-1.5):1. Under conditions of 100-120℃ and a space velocity of 1000-2000 h⁻¹, the catalyst was successfully applied. -1 It operates under conditions where the O2 concentration in the gas phase is 5-8% (v / v%) and the moisture content is less than 2% (v / v%).

[0055] In the first catalyst, nano-sized PdO and PtO2 serve as the main active components, exhibiting excellent oxidation catalytic performance and efficiently catalyzing the oxidation conversion of PH3 and P4. CeO2 possesses good oxygen storage and release properties and redox performance, providing active oxygen for the reaction. V2O5 enhances the catalyst's sulfur resistance. The activated carbon support provides a large specific surface area, which is beneficial for the dispersion of active components and the adsorption of reactants. The overall formulation design achieves highly efficient catalytic oxidation of phosphorus-containing pollutants.

[0056] Specifically, CeO2 has a unique fluorite-type crystal structure, where Ce ions can reversibly switch between +3 and +4 valence states, while lattice oxygen can freely enter and exit the lattice, forming oxygen vacancies. Under oxygen-rich conditions, CeO2 can absorb and store oxygen. 3+ Oxidized to Ce 4+ Under hypoxic conditions, Ce 4+ It will release oxygen and be reduced to Ce. 3+ This oxygen storage and release process can be represented as: This property allows CeO2 to regulate the local oxygen concentration, continuously providing active oxygen for the catalytic oxidation reaction, thereby maintaining stable catalytic activity. Oxygen vacancies on the CeO2 surface can serve as active sites, promoting the activation of oxygen molecules and improving catalytic oxidation efficiency.

[0057] V₂O₅ forms a VOV structure in the catalyst, which exhibits strong resistance to sulfur poisoning. When sulfur-containing compounds come into contact with the catalyst, the sulfates formed on the V₂O₅ surface are easily decomposed, preventing the accumulation of stable sulfides and thus avoiding permanent deactivation of active sites. Furthermore, a strong interaction exists between V₂O₅ and CeO₂, forming a Ce-OV bridging structure, which further enhances the catalyst's redox performance and sulfur resistance. During catalyst regeneration, V₂O₅ also contributes to the oxidative removal of sulfides, enabling the catalyst to maintain high activity continuously.

[0058] The first reactor involves the following reaction formulas: 4PH3 + 8O2 → 2P2O5 + 6H2O; P4 + 5O2 → P2O5;

[0059] P2O5 + 3H2O → 2H3PO4.

[0060] In this embodiment, the operating conditions of the second reactor are:

[0061] 1) Second catalyst formulation:

[0062] The second catalyst is mainly composed of the following components in parts by weight, uniformly mixed:

[0063] CeO2: 5-7 parts;

[0064] V2O5: 3-4 parts;

[0065] MoO3: 2-3 parts;

[0066] γ-Al2O3 support: 86-90 parts;

[0067] The weight ratio of CeO2 to V2O5 is (1.6-1.8):1, and the weight ratio of V2O5 to MoO3 is (1.4-1.6):1.

[0068] 2) Operating parameters of the second reactor: operate at 70-90℃, with a space velocity controlled at 1000-2000 h⁻¹. -1 The moisture content is 15-20% (v / v%).

[0069] It can be seen that the second catalyst mainly consists of CeO2, V2O5, MoO3, and γ-Al2O3 support, with a CeO2 to V2O5 weight ratio of (1.6-1.8):1 and a V2O5 to MoO3 weight ratio of (1.4-1.6):1. Under conditions of 70-90℃ and a space velocity of 1000-2000 h⁻¹, [the catalyst was successfully tested]. -1 It operates under conditions where the moisture content is 15-20% (v / v%).

[0070] CeO2 through Ce 4+ / Ce 3+ Valence state transitions provide ample redox active sites and form a stable Ce-OV structure with V₂O₅, enhancing resistance to poisoning; V₂O₅ provides appropriate acidic sites to promote hydrolysis, and its V-OH groups can activate water molecules to accelerate the hydrolysis process; MoO₃ not only through Mo 6+ It provides additional Lewis acid sites to enhance hydrolysis activity, effectively inhibits sulfur poisoning, and forms Mo-O-Ce structures with other components; the γ-Al2O3 support, through its large specific surface area (>200m²), provides additional Lewis acid sites to enhance hydrolysis activity, effectively inhibits sulfur poisoning, and forms Mo-O-Ce structures with other components; 2The appropriate pore structure ensures high dispersion of the active components, while providing excellent mechanical strength and thermal stability. The precise ratio of the three active components (CeO2:V2O5=(1.6-1.8):1, V2O5:MoO3=(1.4-1.6):1) ensures the optimal balance between acidic sites and redox sites, achieving efficient and stable hydrolytic conversion of organic sulfur under low temperature conditions.

[0071] The hydrolysis and conversion process includes the following reaction formulas: COS + H2O = H2S + CO2 and CS2 + 2H2O = 2H2S + CO2.

[0072] In this embodiment, the operating conditions of the third reactor are as follows:

[0073] 1) Third catalyst formulation:

[0074] The third catalyst is mainly composed of the following components in parts by weight, uniformly mixed:

[0075] Fe2O3: 3-5 parts;

[0076] CuO: 2-3 parts;

[0077] MnO2: 1-2 parts;

[0078] Activated carbon carrier: 90-94 parts;

[0079] The weight ratio of Fe2O3 to CuO is (1.5-1.8):1, and the weight ratio of CuO to MnO2 is (1.8-2.0):1.

[0080] 2) Operating process parameters of the third reactor:

[0081] Operate at 65-85℃, with a controlled airspeed of 800-1500 h⁻¹. -1 The O2 concentration in the gas phase is 3-5% (v / v%), and the moisture content is 2-8% (v / v%).

[0082] The third catalyst mainly consists of Fe₂O₃, CuO, MnO₂, and an activated carbon support, with the weight ratio of Fe₂O₃ to CuO being (1.5-1.8):1, and the weight ratio of CuO to MnO₂ being (1.8-2.0):1. The catalyst operates at 65-85℃ with a space velocity of 800-1500 h⁻¹. -1 It operates under conditions where the O2 concentration in the gas phase is 3-5% (v / v%) and the moisture content is 2-8% (v / v%).

[0083] The third catalyst is actually divided into two components: a first type and a second type. The first type of component contains Fe2O3, CuO, and MnO2, which is used to catalytically react H2S and oxygen in the flue gas to produce elemental sulfur. The second type of component contains an activated carbon support, which is used to further catalytically oxidize the sulfur dioxide generated by the reaction of elemental sulfur with oxygen and then react it with water to produce sulfuric acid.

[0084] Fe2O3 is the main active component, through Fe 3+ / Fe 2+ Valence state cycling catalyzes H2S oxidation; CuO via Cu 2+ / Cu + The conversion enhances electron transfer efficiency; MnO2 provides additional redox sites. The precise ratio of the three oxides (Fe2O3:CuO = (1.5-1.8):1, CuO:MnO2 = (1.8-2.0):1) forms a highly efficient multi-metal oxide composite system, achieving selective oxidation of H2S to elemental sulfur under low-temperature conditions (65-85℃). During the reaction, appropriate oxygen concentration and moisture content help maintain the catalytic cycle and inhibit over-oxidation.

[0085] Activated carbon not only serves as a carrier, providing a large specific surface area for dispersing active components, but more importantly, its surface oxygen-containing functional groups play a crucial role in the second-stage reaction. When a small amount of elemental sulfur is over-oxidized to SO2, the oxygen-containing functional groups on the activated carbon surface can catalyze the further oxidation of SO2, converting it into sulfuric acid in the presence of moisture, thereby achieving deep desulfurization. This bifunctional catalytic system ensures both efficient removal of H2S and treatment of SO2 generated during the process under low-temperature conditions, demonstrating the holistic and advanced nature of the catalyst design.

[0086] It is evident that the three-stage catalytic flue gas treatment achieved by the aforementioned yellow phosphorus tail gas dephosphorization and desulfurization equipment belongs to low-temperature catalytic technology (the first reactor operates at 100-120℃, the second reactor at 70-90℃, and the third reactor at 65-85℃). Furthermore, the temperature of the three-stage catalytic flue gas treatment decreases step by step. This temperature gradient design reduces energy consumption (heater 6 can be a steam heater, and the steam source required for the steam heater is readily available at the yellow phosphorus production plant and can be used directly; and apart from heater 6, the yellow phosphorus tail gas does not need to be heated further), while avoiding catalyst sintering and deactivation that may be caused by excessively high temperatures.

[0087] Figure 2 for Figure 1 A partial enlarged view of the desulfurization unit. Figure 3 for Figure 1 A schematic diagram of the specific structure of the desulfurization unit. (See attached diagram.) Figures 2-3 As shown, the aforementioned desulfurization unit specifically includes: a reaction system, a regenerated liquid circulation system, and a flue gas conveying system. Of course, in conjunction with... Figure 1 As can be seen, the aforementioned dephosphorization unit also includes a reaction system, a regenerated liquid circulation system, and a flue gas conveying system. The following section will focus on explaining the reaction system, regenerated liquid circulation system, and flue gas conveying system of the desulfurization unit.

[0088] like Figures 2-3 As shown, the desulfurization unit's reaction system is used to remove H2S from the flue gas to be treated. It includes at least one reactor (i.e., the third reactor 91), which has an air inlet, an exhaust outlet, a liquid outlet, and a catalyst (i.e., the third catalyst) located in the reactor. The reactor is equipped with a regeneration liquid spraying device for washing and regenerating the catalyst. During operation, the flue gas to be treated enters the reactor through the air inlet, passes through the catalyst, and is then discharged from the exhaust outlet of the reactor as treated flue gas. When the H2S in the flue gas to be treated passes through the catalyst, it reacts on the catalyst to form elemental sulfur and sulfuric acid. The sulfuric acid is generated by further catalytic oxidation of sulfur dioxide produced by the reaction of elemental sulfur with oxygen and then reacting with water. When washing and regenerating the catalyst, the elemental sulfur and the sulfuric acid enter the regeneration liquid sprayed on the catalyst and are then discharged from the reactor's liquid outlet.

[0089] The regenerated liquid circulation system 92 includes at least one regenerated liquid tank 921 and a regenerated liquid circulation control network connecting the at least one regenerated liquid tank 921 and each reactor. The regenerated liquid circulation control network has an output-side control network 922, an input-side control network 923, and a regenerated liquid driving device. The output-side control network 922 can guide the regenerated liquid in the selected regenerated liquid tank 921 into the regenerated liquid spraying device of the selected reactor. The input-side control network 923 can guide the regenerated liquid output from the drain port of the selected reactor into the selected regenerated liquid tank 921. The regenerated liquid driving device can provide the required power to the regenerated liquid.

[0090] The flue gas conveying system 93 includes an intake pipe network 931 and an exhaust pipe network 932. The intake pipe network 931 includes an intake main pipe and intake branch pipes that connect the intake main pipe to the intake ports of each reactor. Each intake branch pipe has an on / off control mechanism. The exhaust pipe network 932 includes an exhaust main pipe and exhaust branch pipes that connect the exhaust main pipe to the exhaust ports of each reactor.

[0091] Each intake branch pipe has a bend 933 that extends downwards, then bends back and extends upwards. When it is necessary to cut off the intake of flue gas in the selected intake branch pipe, liquid sealing liquid is injected into the corresponding bend 933 through the liquid inlet structure provided on the corresponding bend to form a liquid seal. When it is necessary to open up the intake of flue gas in the selected intake branch pipe, the liquid sealing liquid in the corresponding bend is discharged through the liquid outlet structure provided on the corresponding bend 933.

[0092] The above-described structure of the desulfurization device can be referenced to the relevant structures in the catalytic flue gas desulfurization equipment disclosed by the applicant in patent documents with publication numbers CN214764545U, CN114653202A, and CN114797450A. The working process of the desulfurization device in this invention is similar to that of the catalytic flue gas desulfurization equipment in these patent documents.

[0093] However, in the desulfurization device of this invention, the height of the intake side of the bend 933 on each intake branch pipe is set higher than the height of the exhaust side of the bend 933 (see...). Figure 2 The height difference between the air inlet side and the exhaust side of the bend 933 is H. Furthermore, the liquid level of the liquid sealant injected into the bend 933 can rise to the exhaust side of the bend 933 and overflow from the exhaust side channel of the bend 933 to the air inlet of the corresponding reactor.

[0094] By setting the height of the inlet side of the bend 933 on each inlet branch pipe to be higher than the height of the outlet side of the bend 933, it is easier to control the liquid seal liquid level injected into the bend 933 (the overflow point height of the channel on the outlet side of the bend 933), and to ensure that the overflow direction is always towards the inlet of the reactor, preventing the liquid seal liquid from flowing back into the main inlet pipe. This design makes the flow direction of the liquid seal liquid more controllable, improving the reliability and safety of the liquid seal.

[0095] Furthermore, the liquid inlet structure of the bend 933 on each air inlet branch pipe is connected to the at least one regenerated liquid tank via a liquid seal liquid delivery pipeline system. The output-side control network 922 includes an output-side main pipe and output-side branches connecting the main pipe to the regenerated liquid spraying devices of each reactor. Each output-side branch is equipped with a regenerated liquid delivery control valve 924. A liquid seal liquid delivery manifold 925 branches off from the pipe upstream of the corresponding regenerated liquid delivery control valve 924 on each output-side branch. Each liquid delivery manifold is connected to the liquid inlet structure of the bend 933 on the air inlet branch pipe of the corresponding reactor via a corresponding liquid seal liquid delivery control valve 925. The liquid inlet structure is a liquid inlet port located on the exhaust side of the pipe of the corresponding bend 933.

[0096] Thus, when the catalyst in the selected reactor needs to be washed and regenerated, the regenerated liquid in the selected regenerated liquid tank is guided to the regenerated liquid spraying device of the selected reactor through the regenerated liquid circulation system. During this process, the liquid seal liquid delivery control valve corresponding to the selected reactor is first opened for a period of time, so that the liquid level of the liquid seal liquid injected into the corresponding bend rises to the overflow height of the exhaust side of the bend and the liquid seal liquid is discharged from the exhaust side channel of the bend to the air inlet of the corresponding reactor, thereby keeping the liquid level of the liquid seal liquid injected into the corresponding bend below the overflow height of the exhaust side of the bend. Then, the liquid seal liquid delivery control valve corresponding to the selected reactor is closed and the regenerated liquid delivery control valve corresponding to the selected reactor is opened.

[0097] By first opening the liquid seal liquid delivery control valve corresponding to the selected reactor for a period of time, the liquid seal liquid level injected into the corresponding bend is raised to the overflow height of the exhaust side of the bend, and the liquid seal liquid is discharged from the exhaust side channel of the bend to the air inlet of the corresponding reactor. This keeps the liquid seal liquid level injected into the corresponding bend below the overflow height of the exhaust side of the bend. Then, the liquid seal liquid delivery control valve corresponding to the selected reactor is closed, and the regenerated liquid delivery control valve corresponding to the selected reactor is opened. This not only accurately controls the liquid seal liquid level and prevents the liquid seal liquid from flowing back into the air inlet manifold, ensuring the reliability and safety of the liquid seal, but also drives the liquid seal liquid and the regenerated liquid simultaneously through the regenerated liquid drive device.

[0098] As mentioned above, the working process of the yellow phosphorus tail gas dephosphorization and desulfurization equipment in the above embodiment is as follows: the yellow phosphorus tail gas first undergoes water washing treatment through the first washing system and alkaline solution washing treatment through the second washing system. After separation by the gas-liquid separator 3, it enters the gas distribution cylinder 4. The gas distribution cylinder 4 diverts part of the yellow phosphorus tail gas to the gas holder for storage and combustion, while the other part is heated by the heat exchanger 5 and the heater 6, and then sequentially enters the dephosphorization device 7, the organic sulfur hydrolysis conversion device 8, and the desulfurization device 9, finally being discharged as desulfurized flue gas. Experiments have found that after water washing and alkaline washing, the yellow phosphorus tail gas still contains a large amount of inorganic sulfur (H2S) and organic sulfur (COS, CS2, etc.). The composition and content of these sulfides depend on the properties and quality of the raw materials. H2S reacts with oxygen to generate elemental sulfur, which is a yellow solid and will deposit on the surface of the first catalyst, increasing the resistance of the first catalyst layer.

[0099] Therefore, the dephosphorization and desulfurization equipment for yellow phosphorus tail gas in another embodiment of the present invention improves upon the above-mentioned dephosphorization and desulfurization equipment for yellow phosphorus tail gas by adding a pre-desulfurization device before the dephosphorization device 7.

[0100] Figure 4 This is a schematic diagram of a pre-desulfurization device in a yellow phosphorus tail gas dephosphorization and desulfurization equipment according to an embodiment of the present invention. Figure 4As shown, the pre-desulfurization unit 10 adopts a liquid phase absorption process. Its core principle is to use a proprietary liquid phase desulfurizing agent to absorb H2S in the desulfurization tower 101 to become rich liquid. The rich liquid (stored in the rich liquid tank 102) is regenerated by contacting air in the ejector 103 and restored to lean liquid. After being returned to the desulfurization tower 101 for use through the lean liquid tank 104.

[0101] This liquid-phase desulfurizing agent can use a mixed solution of sodium carbonate and sodium arsenite. During absorption, it reacts with H2S to generate NaHS and NaHCO3. Subsequently, upon contact with air in the injector, it undergoes an oxidative regeneration reaction, simultaneously releasing elemental sulfur. The NaOH generated during regeneration reacts with CO2 in the air to regenerate Na2CO3, thus achieving the recycling of the liquid-phase desulfurizing agent. This pre-desulfurization unit 10 can operate at ambient temperature and pressure, featuring simple operation and high efficiency. Sodium arsenite (NaAsO2), as the active component (generally added at a dosage of a few grams per liter), acts as a catalyst to improve regeneration efficiency and reaction rate: it is reduced to arsenite during H2S absorption and oxidized back to sodium arsenite upon contact with air, thus repeating the cycle.

[0102] Of course, the pre-desulfurization unit can also use the same desulfurization unit as desulfurization unit 9. In an optional embodiment, desulfurization unit 9 is a desulfurization tower, in which multiple reactors are distributed, some of which serve as reactors for the pre-desulfurization unit and others as reactors for desulfurization unit 9.

[0103] 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 foregoing content of this specification without inventive effort should fall within the scope of the present invention.

Claims

1. Catalytic flue gas treatment device, characterized in that include: A reaction system for removing H2S from flue gas to be treated includes at least one reactor. The reactor has an inlet, an outlet, a drain outlet, and a catalyst located in the reactor. The reactor is equipped with a regeneration liquid spraying device for washing and regenerating the catalyst. During operation, the flue gas to be treated enters the reactor through the inlet, passes through the catalyst, and then exits through the outlet as treated flue gas. When the H2S in the flue gas passes through the catalyst, it reacts on the catalyst to form elemental sulfur and sulfuric acid. The sulfuric acid is generated by further catalytic oxidation of sulfur dioxide produced by the reaction of elemental sulfur with oxygen and then reacting with water. During the washing and regeneration of the catalyst, the elemental sulfur and the sulfuric acid enter the regeneration liquid sprayed on the catalyst and are then discharged from the outlet of the reactor. A regenerated liquid circulation system includes at least one regenerated liquid tank and a regenerated liquid circulation control network connecting the at least one regenerated liquid tank and each reactor. The regenerated liquid circulation control network has an output-side control network, an input-side control network, and a regenerated liquid driving device. The output-side control network can guide the regenerated liquid in the selected regenerated liquid tank to the regenerated liquid spraying device of the selected reactor. The input-side control network can guide the regenerated liquid output from the drain outlet of the selected reactor to the selected regenerated liquid tank. The regenerated liquid driving device can provide the required power to the regenerated liquid. A flue gas conveying system includes an intake pipe network and an exhaust pipe network. The intake pipe network includes an intake main pipe and intake branch pipes that connect the intake main pipe to the intake ports of each reactor. Each intake branch pipe has an on / off control mechanism. The exhaust pipe network includes an exhaust main pipe and exhaust branch pipes that connect the exhaust main pipe to the exhaust ports of each reactor. The catalyst comprises a first type of component and a second type of component. The first type of component is used to catalytically react H2S and oxygen in the flue gas to be treated to generate elemental S. The second type of component is used to further catalytically oxidize the sulfur dioxide generated by the reaction of elemental S with oxygen and react it with water to generate sulfuric acid. The catalyst is mainly composed of the following components in parts by weight, uniformly mixed: First type of component: Fe2O3: 3-5 parts; CuO: 2-3 parts; MnO2: 1-2 parts; Second type of component: Activated carbon carrier: 90-94 parts; The weight ratio of Fe2O3 to CuO is (1.5-1.8):1, and the weight ratio of CuO to MnO2 is (1.8-2.0):

1. The reactor operating parameters are as follows: operation at 65-85℃, with a space velocity controlled at 800-1500 h⁻¹. -1 The O2 concentration in the gas phase is 3-5% (v / v%), and the moisture content is 2-8% (v / v%).

2. Catalytic flue gas treatment device according to claim 1, characterised in that: Each intake branch pipe has a bend that extends downwards, then bends back and extends upwards. When it is necessary to cut off the intake of flue gas in the selected intake branch pipe, liquid seal liquid is injected into the corresponding bend through the liquid inlet structure set on the corresponding bend to form a liquid seal. When it is necessary to open up the intake of flue gas in the selected intake branch pipe, the liquid seal liquid in the corresponding bend is discharged through the liquid outlet structure set on the corresponding bend.

3. Catalytic flue gas treatment device according to claim 2, characterised in that: The height of the intake side of the bend on each intake manifold is higher than the height of the exhaust side of the bend.

4. Catalytic flue gas treatment device according to claim 3, characterised in that: The liquid level of the liquid seal injected into the bend can rise to the exhaust side of the bend and overflow from the exhaust side channel of the bend to the air inlet of the corresponding reactor.

5. Catalytic flue gas treatment device according to claim 4, characterised in that: The liquid inlet structure of the bend on each air inlet branch pipe is connected to the at least one regeneration liquid tank through a liquid seal liquid delivery pipeline system.

6. The catalytic flue gas treatment device as described in claim 5, characterized in that: The output-side control network includes an output-side main pipe and output-side branches connecting the output-side main pipe to the regenerated liquid spraying device of each reactor. Each output-side branch is equipped with a regenerated liquid delivery control valve. A liquid sealing liquid delivery manifold branches out from the pipes on each output-side branch before the corresponding regenerated liquid delivery control valve. Each liquid delivery manifold is connected to the liquid inlet structure of the bend on the air inlet branch of the corresponding reactor through a liquid sealing liquid delivery control valve that is installed on the liquid delivery manifold.

7. The catalytic flue gas treatment device as described in claim 6, characterized in that: The liquid inlet structure is a liquid inlet port located on the exhaust side of the pipe at the corresponding bend.

8. Catalytic flue gas treatment device according to claim 6, characterised in that: When the catalyst in the selected reactor needs to be washed and regenerated, the regenerated liquid in the selected regenerated liquid tank is guided to the regenerated liquid spraying device of the selected reactor through the regenerated liquid circulation system. During this process, the liquid seal liquid delivery control valve corresponding to the selected reactor is first opened for a period of time, so that the liquid level of the liquid seal liquid injected into the corresponding bend rises to the overflow height of the exhaust side of the bend and the liquid seal liquid is discharged from the exhaust side channel of the bend to the air inlet of the corresponding reactor, thereby keeping the liquid level of the liquid seal liquid injected into the corresponding bend below the overflow height of the exhaust side of the bend. Then the liquid seal liquid delivery control valve corresponding to the selected reactor is closed and the regenerated liquid delivery control valve corresponding to the selected reactor is opened.

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