A method and system for reducing and recycling desulfurization waste

Abstract

The application discloses a kind of desulfurization waste reduction regeneration and resource utilization method and system, it is related to solid waste resource technology field.The desulfurization waste reduction regeneration and resource utilization method includes the following steps: methanol is carried out catalytic cracking reaction under the action of catalyst, obtains the mixed gas containing carbon monoxide and hydrogen;Mixed reducing gas is imported into calcium-based fixed bed desulfurization waste, make the calcium sulfate contained therein carry out reduction reaction, the calcium sulfite contained therein carries out thermal decomposition reaction, obtains the solid product containing calcium oxide and the gaseous product containing sulfur dioxide;Steam activation and modification treatment are carried out to the solid product containing calcium oxide, obtain activated solid product, and the activated solid product is carried out secondary hydration, and obtains regenerated desulfurizer;Gas product is absorbed by sodium carbonate solution to obtain sodium metabisulfite product.The method provided by the application realizes desulfurizer closed loop circulation and sulfur resource recycling, with low energy consumption, no secondary solid waste.

Description

Technical Field

[0001] This invention relates to the field of solid waste resource utilization technology, and in particular to a method and system for the reduction, regeneration and resource utilization of desulfurization waste. Background Technology

[0002] Calcium-based fixed-bed desulfurization technology is widely used for the desulfurization and purification of sulfur-containing gases such as industrial flue gas. Its desulfurizing agent's main component is Ca(OH)2, which reacts with sulfur-containing gases such as H2S and SO2 during the desulfurization process to generate CaSO3 and CaSO4, achieving a desulfurization efficiency of over 95%. This technology is widely used in industries such as coking, steel, and chemicals, but it generates a large amount of saturated and ineffective desulfurization waste annually.

[0003] Currently, after calcium-based fixed-bed desulfurizers become saturated and fail, the industry generally adopts the following disposal methods: (1) landfill disposal, sending the failed desulfurizers to landfills as general industrial solid waste, which occupies land resources and poses a risk of soil and groundwater pollution; (2) cement kiln co-processing, mixing desulfurization waste into cement raw materials, but the mixing ratio is limited (generally not exceeding 5%), and the amount consumed is limited; (3) brick / building material blending, which is limited by sulfur content and has low added value; (4) soil conditioner, which has strict requirements on waste composition and extremely limited applicable scenarios; (5) high-temperature direct thermal regeneration, which decomposes and reduces CaSO4 to CaO at a high temperature of 1200-1400℃, which has extremely high energy consumption and the sintering of CaO at high temperature leads to a significant decrease in specific surface area, and the desulfurization activity after regeneration is only 60%-70% of that of fresh desulfurizers; (6) water washing-acid dissolution method, which generates a large amount of sulfur-containing wastewater and cannot achieve direct regeneration and reuse of desulfurizers.

[0004] None of the above-mentioned treatment methods achieve the resource recycling of desulfurization waste, resulting in a double waste of calcium and sulfur resources. Therefore, there is still a lack of a technical solution that can achieve efficient regeneration of calcium-based desulfurizing agents and simultaneous recovery of sulfur resources under moderate temperature conditions. Summary of the Invention

[0005] The main objective of this invention is to propose a method and system for the reduction, regeneration, and resource utilization of desulfurization waste, aiming to solve the problem of the lack of effective resource utilization methods for calcium-based fixed-bed desulfurization waste.

[0006] To achieve the above objectives, this invention proposes a method for the reduction, regeneration, and resource utilization of desulfurization waste, used to treat calcium-based fixed-bed desulfurization waste, comprising the following steps: Methanol is subjected to catalytic cracking reaction in the presence of a catalyst to obtain a mixed gas containing carbon monoxide and hydrogen. The mixed gas is then mixed with a dilution gas to obtain a mixed reducing gas. Provide calcium-based fixed-bed desulfurization waste containing calcium sulfate and / or calcium sulfite; Under heating conditions, the mixed reducing gas is introduced into the calcium-based fixed bed desulfurization waste, causing the calcium sulfate contained therein to undergo a reduction reaction and the calcium sulfite contained therein to undergo a thermal decomposition reaction, to obtain a solid product containing calcium oxide and a gaseous product containing sulfur dioxide. Steam is introduced into the solid product and a modifier is added to cause the calcium oxide in the solid product to undergo a hydration reaction to obtain a hydrated product. The hydrated product is then heated and dehydrated to decompose the calcium hydroxide in the hydrated product into calcium oxide, thereby obtaining an activated solid product. The activated solid product is then subjected to secondary hydration and granulation to obtain a regenerated calcium-based fixed-bed desulfurizer. The gaseous product is passed into a sodium carbonate solution for absorption reaction to obtain a solution containing sodium bisulfite. The solution containing sodium bisulfite is then subjected to a dehydration condensation reaction to obtain sodium metabisulfite.

[0007] In one embodiment, the step of catalytically cracking methanol in the presence of a catalyst to obtain a mixed gas containing carbon monoxide and hydrogen, and then mixing the mixed gas with a dilution gas to obtain a mixed reducing gas: The catalyst is a molybdenum carbide-supported noble metal catalyst, which includes a molybdenum carbide-supported platinum catalyst; and / or, The volume ratio of the mixed gas to the diluent gas is 1:(1~3); and / or, The diluting gas includes nitrogen.

[0008] In one embodiment, the step of providing calcium-based fixed-bed desulfurization waste containing calcium sulfate and / or calcium sulfite includes: Provide calcium-based fixed-bed desulfurization waste containing calcium sulfate and / or calcium sulfite for crushing and screening; wherein the screened particles are 3~6 mm particles.

[0009] In one embodiment, the step of introducing the mixed reducing gas into the calcium-based fixed-bed desulfurization waste under heating conditions, causing the calcium sulfate contained therein to undergo a reduction reaction and the calcium sulfite contained therein to undergo a thermal decomposition reaction, to obtain a solid product containing calcium oxide and a gaseous product containing sulfur dioxide: The heating temperature is 700~900℃, and the heating time is 2~6 h; and / or, The space velocity of the mixed reducing gas is 500-600 h⁻¹. -1 .

[0010] In one embodiment, in the step of introducing steam into the solid product and adding a modifier to cause the calcium oxide in the solid product to undergo a hydration reaction to obtain a hydrated product, the modifier includes a first modifier and a second modifier, the first modifier including isopropanol and the second modifier including sodium citrate; and / or, The pressure of the introduced steam is 0.3~0.4 MPa, and the time of introduction is 0.5~2 h; and / or, The modifier is added in multiple stages.

[0011] In one embodiment, the modifier is added in two stages. The first stage involves adding 40% to 60% of the total mass of the modifier within 0 to 30 minutes after the start of the hydration reaction. The second stage involves adding the remaining modifier within 30 to 60 minutes after the completion of the first stage. And / or, The amount of isopropanol added is 1-2% of the mass of calcium oxide, calculated based on the mass of calcium oxide in the solid product; the amount of sodium citrate added is 1-2% of the mass of calcium oxide, calculated based on the mass of calcium oxide in the solid product.

[0012] In one embodiment, the step of sequentially subjecting the activated solid product to secondary hydration and granulation to obtain a regenerated calcium-based fixed-bed desulfurizer includes: The temperature for the secondary hydration is 60~90℃, and the time for the secondary hydration is 0.5~2 h.

[0013] This invention also proposes a system for the reduction, regeneration, and resource utilization of desulfurization waste, used to treat calcium-based fixed-bed desulfurization waste. The system includes a desulfurization waste pretreatment unit, a reducing gas preparation unit, a fixed-bed reduction-thermal decomposition unit, a regenerated desulfurizing agent production unit, and a sodium metabisulfite production unit; wherein: The desulfurization waste pretreatment unit includes a crushing and screening device, which is used to crush and screen the calcium-based fixed bed desulfurization waste to obtain pretreated waste. The reducing gas preparation unit includes a methanol catalytic cracking reactor, a dilution gas supply device, and a gas mixing device. The methanol catalytic cracking reactor and the dilution gas supply device are respectively connected to the gas mixing device. The methanol catalytic cracking reactor is used to carry out a catalytic cracking reaction of methanol under the action of a catalyst to obtain a mixed gas containing carbon monoxide and hydrogen. The gas mixing device is used to mix the mixed gas containing carbon monoxide and hydrogen with the dilution gas to obtain a mixed reducing gas. The fixed-bed reduction-thermal decomposition unit includes a fixed-bed reactor, a solid product collection device, and a gaseous product collection device. The fixed-bed reactor is connected to the crushing and screening device and the gas mixing device, respectively, to react the pretreated waste with the mixed reducing gas, causing the calcium sulfate in the reactor to undergo a reduction reaction and the calcium sulfite in the reactor to undergo a thermal decomposition reaction, generating a solid product containing calcium oxide and a gaseous product containing sulfur dioxide. The solid product collection device and the gaseous product collection device are connected to the solid outlet and gas outlet of the fixed-bed reactor, respectively. The regenerated desulfurizing agent production unit includes a cooling device, a primary hydration device, a dehydration device, and a secondary hydration device connected in sequence. The cooling device is connected to the solid product collection device and is used to cool the calcium oxide-containing solid product. The primary hydration device is used to perform a primary hydration reaction on the cooled solid product to obtain a first hydrated product. The dehydration device is used to perform a dehydration reaction on the first hydrated product to obtain an activated solid product. The secondary hydration device is used to perform a secondary hydration on the activated solid product, converting the calcium oxide in the activated solid product into calcium hydroxide to obtain a second hydrated product. The sodium metabisulfite production unit includes a sodium metabisulfite reaction device, which is connected to the gas product collection device. The reaction device is used to allow the sulfur dioxide-containing gaseous product to undergo an absorption reaction with the sodium carbonate solution through the sodium metabisulfite reaction device to obtain sodium metabisulfite.

[0014] In one embodiment, the regenerated desulfurizer production unit further includes a heat recovery device, which is connected to the cooling device and the methanol catalytic cracking reactor, respectively, and is used to recover the heat generated during the cooling process of the cooling device and transfer it to the methanol catalytic cracking reactor.

[0015] In one embodiment, the regenerated desulfurizing agent production unit further includes a granulation device, which is connected to the secondary hydration device and is used to granulate the second hydration product.

[0016] The present invention provides a method for the reduction, regeneration, and resource utilization of desulfurization waste. This method first utilizes a methanol catalytic cracking reaction to generate a mixed gas containing hydrogen and carbon monoxide, which is then diluted with a dilution gas to keep the concentrations of hydrogen and carbon monoxide far from their explosion limits, ensuring operational safety. Then, on one hand, hydrogen and carbon monoxide are used to reduce calcium sulfate in the calcium-based fixed-bed desulfurization waste to calcium oxide, generating sulfur dioxide. On the other hand, under heating conditions, calcium sulfite contained in the calcium-based fixed-bed desulfurization waste undergoes a thermal decomposition reaction to generate calcium oxide. The process involves reacting sulfur dioxide with calcium oxide to obtain a solid product containing calcium oxide and a gaseous product containing sulfur dioxide. Then, steam is passed through the solid product containing calcium oxide, and a modifier is introduced to obtain a hydrated product. This hydrated product is then heated and dehydrated, thereby activating and modifying the calcium oxide in the solid product to obtain an activated solid product. This activated solid product is then subjected to secondary hydration, converting the calcium oxide into calcium hydroxide, thus obtaining a regenerated calcium-based fixed-bed desulfurizing agent. Simultaneously, the gaseous product containing sulfur dioxide is absorbed by a sodium carbonate solution, and after dehydration and condensation, sodium metabisulfite is generated. Using the resource utilization method provided by this invention, all desulfurization waste can be reused after regeneration without generating secondary solid waste. This not only achieves a closed-loop cycle of the desulfurizing agent but also restores the desulfurization efficiency of the regenerated desulfurizing agent to over 98%, allowing for multiple cycles and significantly reducing the procurement cost of the desulfurizing agent and the consumption of calcium resources. Furthermore, it converts the sulfur element in the desulfurization waste into sodium metabisulfite, realizing the resource utilization of the waste. Furthermore, the resource utilization method of the present invention incorporates a modifier to synergistically create pores during the steam activation process. Compared with the method without the modifier, this method is more conducive to forming a uniform and well-developed pore structure, increasing the specific surface area of ​​calcium oxide, and providing more active sites. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the system for the reduction, regeneration, and resource utilization of desulfurization waste provided by the present invention; Figure 2 This is a comparison chart of the specific surface area of ​​CaO in the solid products of Examples 2-4 of the present invention before and after activation; Figure 3 The graphs show the relationship between the number of regeneration cycles and the desulfurization efficiency of the regenerated calcium-based fixed-bed desulfurizer in Examples 2 and 4 of this invention.

[0019] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0022] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0023] Calcium-based fixed-bed desulfurization technology is widely used in industries such as coking, steel, and chemicals, but it generates a large amount of saturated and ineffective desulfurization waste every year. Currently, after the calcium-based fixed-bed desulfurizer becomes saturated and ineffective, the industry generally uses methods such as landfill disposal, co-processing in cement kilns, blending in brick / building materials, use in soil conditioners, high-temperature direct thermal regeneration, and water washing-acid dissolution for disposal. However, these existing technologies not only make it difficult to achieve the resource recycling of desulfurization waste, but also result in a double waste of calcium and sulfur resources. Therefore, there is still a lack of a technical solution that can achieve efficient regeneration of calcium-based desulfurizers and simultaneous recovery of sulfur resources under moderate temperature conditions.

[0024] In view of this, the present invention proposes a method for the reduction, regeneration, and resource utilization of desulfurization waste, used to treat calcium-based fixed-bed desulfurization waste, comprising the following steps: Methanol is subjected to catalytic cracking reaction in the presence of a catalyst to obtain a mixed gas containing carbon monoxide and hydrogen. The mixed gas is then mixed with a dilution gas to obtain a mixed reducing gas. Provide calcium-based fixed-bed desulfurization waste containing calcium sulfate and / or calcium sulfite; Under heating conditions, the mixed reducing gas is introduced into the calcium-based fixed bed desulfurization waste, causing the calcium sulfate contained therein to undergo a reduction reaction and the calcium sulfite contained therein to undergo a thermal decomposition reaction, to obtain a solid product containing calcium oxide and a gaseous product containing sulfur dioxide. Steam is introduced into the solid product and a modifier is added to cause the calcium oxide in the solid product to undergo a hydration reaction to obtain a hydrated product. The hydrated product is then heated and dehydrated to decompose the calcium hydroxide in the hydrated product into calcium oxide, thereby obtaining an activated solid product. The activated solid product is then subjected to secondary hydration and granulation to obtain a regenerated calcium-based fixed-bed desulfurizer. The gaseous product is passed into a sodium carbonate solution for absorption reaction to obtain a solution containing sodium bisulfite. The solution containing sodium bisulfite is then subjected to a dehydration condensation reaction to obtain sodium metabisulfite.

[0025] The present invention provides a method for the reduction, regeneration, and resource utilization of desulfurization waste. First, a mixed gas containing hydrogen and carbon monoxide is generated by the catalytic cracking reaction of methanol, and diluted with a dilution gas to keep the concentrations of hydrogen and carbon monoxide far from the explosion limits, ensuring operational safety. Then, on one hand, hydrogen and carbon monoxide are used to reduce calcium sulfate in the calcium-based fixed-bed desulfurization waste to calcium oxide, generating sulfur dioxide. On the other hand, under heating conditions, calcium sulfite contained in the calcium-based fixed-bed desulfurization waste undergoes a thermal decomposition reaction to generate calcium oxide and sulfur dioxide, thereby obtaining a solid product containing calcium oxide and a gaseous product containing sulfur dioxide. Next, steam is passed through the calcium oxide-containing solid product, and a modifier is introduced to obtain a hydrated product. The hydrated product is then heated and dehydrated, thereby activating and modifying the calcium oxide in the solid product to obtain an activated solid product. The activated solid product is then subjected to secondary hydration to convert calcium oxide into calcium hydroxide, thus obtaining a regenerated calcium-based fixed-bed desulfurizing agent. Simultaneously, sodium carbonate solution is used to absorb the gaseous product containing sulfur dioxide, and after dehydration and condensation, sodium metabisulfite is generated as a product. The resource utilization method provided by this invention enables the complete reuse of desulfurization waste after regeneration, without generating secondary solid waste. This not only achieves a closed-loop cycle of the desulfurizing agent but also restores the desulfurization efficiency of the regenerated desulfurizing agent to over 98%, allowing for multiple cycles and significantly reducing the procurement cost of desulfurizing agents and calcium resource consumption. Simultaneously, it converts the sulfur element in the desulfurization waste into sodium metabisulfite, realizing the resource utilization of the waste. This method is suitable for the disposal of calcium-based fixed-bed desulfurization waste in industries such as coking, steel, and chemicals. Furthermore, the resource utilization method of this invention incorporates a modifier during steam activation to synergistically create pores. Compared to the method without a modifier, the calcium oxide in the solid product is more conducive to forming a uniform and well-developed pore structure, resulting in a superior specific surface area and providing more reactive sites.

[0026] It should be noted that the main component of the regenerated desulfurizer is calcium hydroxide (Ca(OH)2), which is consistent with the composition of the fresh desulfurizer. Therefore, no drying treatment is required to maintain its high desulfurization activity. The specific surface area of ​​the regenerated calcium hydroxide, activated by pressurized steam, can be increased to 25-50 m². 2 / g, exhibiting excellent desulfurization activity.

[0027] It should be noted that the reaction formulas for reducing calcium sulfate in calcium-based fixed-bed desulfurization waste to calcium oxide and generating sulfur dioxide using hydrogen and carbon monoxide are: CaSO4 + H2 → CaO + SO2↑ + H2O; CaSO4 + CO → CaO + SO2↑ + CO2↑; the reaction formula for the high-temperature decomposition reaction of calcium sulfite is: CaSO3 → CaO + SO2; the reaction formula involved in the step of passing the calcium oxide-containing solid product through steam and introducing a modifier to obtain the hydrated product is: CaO + H2O → Ca(OH)2; the reaction formula involved in the step of heating and dehydrating the hydrated product to activate and modify the calcium oxide in the solid product to obtain the activated solid product is: Ca(OH)2 → CaO + H2O; the reaction formula involved in the second hydration of the activated solid product to obtain the second hydrated product (i.e., the regenerated calcium-based fixed-bed desulfurizer) is: CaO + H2O → The sulfur dioxide contained in the gaseous product Ca(OH)2 is first absorbed by sodium carbonate and reacted to be converted into sodium bisulfite. Subsequently, the sodium bisulfite is heated, concentrated, and dehydrated to produce sodium metabisulfite (Na2S2O5). The reaction formulas involved in this process are: 2SO2+Na2CO3+H2O → 2NaHSO3+CO2↑, 2NaHSO3→ Na2S2O5+H2O.

[0028] It should be noted that the reaction of methanol to produce hydrogen and carbon monoxide can be carried out at 150-190℃, and the required heat can be supplied by the waste heat in the cooling process of the solid product containing calcium oxide, thereby achieving the system's heat self-balance.

[0029] Furthermore, through simplified heat balance calculations, it can be seen that the CaO in each ton of desulfurization ash can release about 700~900 MJ of heat when cooled from 800℃ to 200℃, while the methanol catalytic cracking reaction (CH3OH → 2H2+ CO, ΔH ≈+90.7 kJ / mol) required for each ton of desulfurization ash absorbs about 280~400 MJ of heat. Therefore, in addition to meeting the methanol cracking requirements, there is still 300~500 MJ of surplus heat, which can be utilized by external steam supply.

[0030] In an embodiment of the present invention, in the step of catalytically cracking methanol under the action of a catalyst to obtain a mixed gas containing carbon monoxide and hydrogen, and mixing the mixed gas with a dilution gas to obtain a mixed reducing gas, the catalyst is a molybdenum carbide supported noble metal catalyst, which includes a molybdenum carbide supported platinum catalyst (Pt / α-MoC catalyst).

[0031] The use of molybdenum carbide-supported noble metal catalysts can achieve efficient catalytic cracking of methanol to produce hydrogen at low temperatures of 150–190 °C. Currently, most methods for hydrogen production using molybdenum carbide-supported noble metal catalysts are applied in the hydrogen energy sector, and there are no reports of their application in desulfurization waste reduction and regeneration processes.

[0032] It should be noted that the Pt / α-MoC catalyst can be purchased or prepared in-house. In the embodiments of the present invention, the Pt / α-MoC catalyst is prepared by a wet impregnation-reduction method, and the preparation method includes the following steps: The α-MoC support was dispersed in water to obtain a suspension; Add H2PtCl6·6H2O and stir and impregnate at 80℃ for 6 h; After removing moisture by rotary evaporation, the resulting solid is dried under vacuum. The dried solid was reduced under a hydrogen-containing atmosphere to obtain the Pt / α-MoC catalyst; it was then cooled and stored under an inert atmosphere.

[0033] In an embodiment of the present invention, in the step of catalytically cracking methanol under the action of a catalyst to obtain a mixed gas containing carbon monoxide and hydrogen, and then mixing the mixed gas with a dilution gas to obtain a mixed reducing gas, the volume ratio of the mixed gas to the dilution gas is 1:(1~3). Exemplarily, the volume ratio of the mixed gas to the dilution gas can be 1:1, 1:2, or 1:3. Setting the amount of dilution gas within this range keeps the CO and H2 concentrations away from the explosion limits, ensuring operational safety, while simultaneously ensuring a sufficient reducing gas concentration to guarantee the reaction rate.

[0034] In an embodiment of the present invention, in the step of catalytically cracking methanol under the action of a catalyst to obtain a mixed gas containing carbon monoxide and hydrogen, and mixing the mixed gas with a dilution gas to obtain a mixed reducing gas, the dilution gas includes nitrogen.

[0035] In an embodiment of the present invention, the step of providing calcium-based fixed-bed desulfurization waste containing calcium sulfate and / or calcium sulfite includes: providing calcium-based fixed-bed desulfurization waste containing calcium sulfate and / or calcium sulfite, and subjecting it to crushing and screening; wherein the screened particles are 3-6 mm in size. Crushing the calcium-based fixed-bed desulfurization waste into 3-6 mm particles facilitates a complete reaction and removes useless dust. It should be noted that the calcium-based fixed-bed desulfurization waste itself has a low moisture content (usually <5%), and no separate drying is required during pretreatment; it can be directly crushed and screened. The residual moisture in the waste will vaporize during the reduction reaction heating process and enter the sulfur recovery system along with the SO2-containing gaseous products.

[0036] In an embodiment of the present invention, in the step of introducing the mixed reducing gas into the calcium-based fixed-bed desulfurization waste under heating conditions, causing the calcium sulfate contained therein to undergo a reduction reaction and the calcium sulfite contained therein to undergo a thermal decomposition reaction to obtain a solid product containing calcium oxide and a gaseous product containing sulfur dioxide, the heating temperature is 700~900℃ and the heating time is 2~6 h. Exemplarily, the heating temperature can be 700℃, 750℃, 800℃, 850℃ or 900℃, and the heating time can be 2 h, 3 h, 4 h, 5 h or 6 h.

[0037] The present invention sets the temperature of the above-mentioned reduction reaction and thermal decomposition reaction at 700~900℃, and reduces energy consumption under medium temperature conditions. Moreover, this temperature range is much lower than the traditional thermal regeneration temperature (1200℃), and the energy consumption is reduced by more than 30%.

[0038] In an embodiment of the present invention, in the step of introducing the mixed reducing gas into the calcium-based fixed-bed desulfurization waste under heating conditions, causing the calcium sulfate contained therein to undergo a reduction reaction and the calcium sulfite contained therein to undergo a thermal decomposition reaction to obtain a solid product containing calcium oxide and a gaseous product containing sulfur dioxide, the space velocity of the mixed reducing gas is 500-600 h⁻¹. -1 For example, the space velocity of the mixed reducing gas can be 500 h⁻¹. -1 550 h -1 or 600 h -1 .

[0039] In an embodiment of the present invention, in the step of introducing water vapor into the solid product and adding a modifier to cause the calcium oxide in the solid product to undergo a hydration reaction to obtain a hydrated product, the modifier includes a first modifier and a second modifier. The first modifier includes isopropanol, and the second modifier includes sodium citrate (trisodium citrate).

[0040] This invention employs a composite modifier. Compared to using a single isopropanol or sodium citrate as a modifier, the composite modifier results in a larger specific surface area and a smaller contact angle for the activated calcium oxide in the solid product. This is because isopropanol (IPA) is a moderately polar organic solvent, and trisodium citrate is a strong complexing agent containing three carboxyl groups (-COO). - After the addition of isopropanol and sodium citrate, IPA preferentially adsorbs onto the surface of CaO particles with the hydrophobic groups facing outwards. This reduces the surface tension of water vapor (72 mN / m → 35 mN / m) and enhances the wettability of water vapor on the CaO particle surface. Subsequently, water vapor enters the macropores of CaO under capillary force, "opening" the macropores into mesopores and increasing the specific surface area. The reaction of trisodium citrate with Ca... 2+Forms stable complexes that can complex free Ca 2+ Ions prevent pore blockage and can also disperse CaO particles through chelation to prevent aggregation.

[0041] In an embodiment of the present invention, in the step of introducing steam into the solid product and adding a modifier to cause the calcium oxide in the solid product to undergo a hydration reaction to obtain a hydrated product, the pressure of the steam introduced is 0.3~0.4 MPa, and the time of introducing the steam is 0.5~2 h. Exemplarily, the pressure of the steam introduced can be 0.3 MPa, 0.35 MPa, or 0.4 MPa, and the time of introducing the steam can be 0.5 h, 1 h, 1.5 h, or 2 h. The present invention sets the steam introduction pressure to 0.3~0.4 MPa and the steam introduction time to 0.5~2 h, resulting in better activation of calcium oxide and higher energy utilization.

[0042] In an embodiment of the present invention, in the step of introducing steam and adding a modifier to the solid product to induce a hydration reaction of calcium oxide in the solid product to obtain a hydrated product, the solid product is cooled to below 200°C before steam is introduced. The present invention utilizes 0.3-0.4 MPa steam to initiate a hydration-dehydration cycle within the CaO particles, forming a stable microporous framework and increasing the specific surface area to 25-50 m². 2 / g. Activation is carried out using steam, which has a low activation temperature (feed temperature below 200℃, steam temperature 133-144℃) and energy consumption is much lower than that of traditional high-temperature activation methods.

[0043] In an embodiment of the present invention, in the step of introducing water vapor into the solid product and adding a modifier to cause the calcium oxide in the solid product to undergo a hydration reaction to obtain a hydrated product, the modifier is added in multiple stages. This step-by-step addition of the modifier ensures a complete reaction and minimizes the amount consumed.

[0044] In an embodiment of the present invention, the modifier is added in two parts. The first addition is 40% to 60% of the total mass of the modifier, and is added within 0 to 30 minutes after the start of the hydration reaction. The second addition is the remaining amount of modifier, and is added within 30 to 60 minutes after the completion of the first addition.

[0045] In embodiments of the present invention, the amount of isopropanol added is 1-2% of the mass of calcium oxide in the solid product; the amount of sodium citrate added is 1-2% of the mass of calcium oxide in the solid product. Controlling the addition of isopropanol and sodium citrate to within 2% saves on usage and ensures sufficient modification.

[0046] In an embodiment of the present invention, in the step of sequentially subjecting the activated solid product to secondary hydration and granulation to obtain a regenerated calcium-based fixed-bed desulfurizer: the secondary hydration temperature is 60~90℃, and the secondary hydration time is 0.5~2 h. Exemplarily, the secondary hydration temperature can be 60℃, 70℃, 80℃, or 90℃, and the secondary hydration time can be 0.5 h, 1 h, 1.5 h, or 2 h.

[0047] Please see Figure 1 This invention also proposes a system for the reduction, regeneration, and resource utilization of desulfurization waste, used to treat calcium-based fixed-bed desulfurization waste. The system includes a desulfurization waste pretreatment unit, a reducing gas preparation unit, a fixed-bed reduction-thermal decomposition unit, a regenerated desulfurizing agent production unit, and a sodium metabisulfite production unit; wherein: The desulfurization waste pretreatment unit includes a crushing and screening device, which is used to crush and screen the calcium-based fixed bed desulfurization waste to obtain pretreated waste. The reducing gas preparation unit includes a methanol catalytic cracking reactor, a dilution gas supply device, and a gas mixing device. The methanol catalytic cracking reactor and the dilution gas supply device are respectively connected to the gas mixing device. The methanol catalytic cracking reactor is used to carry out a catalytic cracking reaction of methanol under the action of a catalyst to obtain a mixed gas containing carbon monoxide and hydrogen. The gas mixing device is used to mix the mixed gas containing carbon monoxide and hydrogen with the dilution gas to obtain a mixed reducing gas. The fixed-bed reduction-thermal decomposition unit includes a fixed-bed reactor, a solid product collection device, and a gaseous product collection device. The fixed-bed reactor is connected to the crushing and screening device and the gas mixing device, respectively, to react the pretreated waste with the mixed reducing gas, causing the calcium sulfate in the reactor to undergo a reduction reaction and the calcium sulfite in the reactor to undergo a thermal decomposition reaction, generating a solid product containing calcium oxide and a gaseous product containing sulfur dioxide. The solid product collection device and the gaseous product collection device are connected to the solid outlet and gas outlet of the fixed-bed reactor, respectively. The regenerated desulfurizing agent production unit includes a cooling device, a primary hydration device, a dehydration device, and a secondary hydration device connected in sequence. The cooling device is connected to the solid product collection device and is used to cool the calcium oxide-containing solid product. The primary hydration device is used to perform a primary hydration reaction on the cooled solid product to obtain a first hydrated product. The dehydration device is used to perform a dehydration reaction on the first hydrated product to obtain an activated solid product. The secondary hydration device is used to perform a secondary hydration on the activated solid product, converting the calcium oxide in the activated solid product into calcium hydroxide to obtain a second hydrated product. The sodium metabisulfite production unit includes a sodium metabisulfite reaction device, which is connected to the gas product collection device. The reaction device is used to allow the sulfur dioxide-containing gaseous product to undergo an absorption reaction with the sodium carbonate solution through the sodium metabisulfite reaction device to obtain sodium metabisulfite.

[0048] The system for desulfurization waste reduction, regeneration, and resource utilization provided by this invention includes a desulfurization waste pretreatment unit, a reducing gas preparation unit, a fixed-bed reduction-thermal decomposition unit, a regenerated desulfurizing agent production unit, and a sodium metabisulfite production unit. The desulfurization waste is treated by the pretreatment unit to improve treatment efficiency. Subsequently, the pretreated waste reacts with the mixed reducing gas produced by the reducing gas preparation unit in the fixed-bed reduction-thermal decomposition unit to generate a solid product containing calcium oxide and a gaseous product containing sulfur dioxide. The solid product containing calcium oxide is then processed by the regenerated desulfurizing agent production unit to obtain a regenerated desulfurizing agent, and the gaseous product containing sulfur dioxide is processed by the sodium metabisulfite production unit to obtain sodium metabisulfite. The system for desulfurization waste reduction, regeneration, and resource utilization provided by this invention can achieve a closed-loop cycle of calcium-based fixed-bed desulfurizing agents and sulfur resource recovery and utilization. It has low energy consumption, produces no secondary solid waste, and is suitable for the disposal of calcium-based fixed-bed desulfurization waste in industries such as coking, steel, and chemicals.

[0049] In an embodiment of the present invention, the regenerated desulfurizer production unit further includes a heat recovery device, which is connected to both the cooling device and the methanol catalytic cracking reactor. This heat recovery device recovers heat generated during the cooling process of the cooling device and transfers it to the methanol catalytic cracking reactor. The residual heat from the calcium oxide-containing solid product in the cooling device during the cooling process is collected and transferred to the methanol catalytic cracking reactor, where it catalyzes the reaction of methanol to produce hydrogen and carbon monoxide, achieving system heat self-balance.

[0050] In an embodiment of the present invention, the regenerated desulfurizing agent production unit further includes a granulation device, which is connected to the secondary hydration device and is used to granulate the second hydration product.

[0051] The technical solution of the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings. It should be understood that the following embodiments are only used to explain the present invention and are not intended to limit the present invention.

[0052] Example 1 A method for preparing a Pt / α-MoC catalyst includes the following steps: (1) Weigh 10 g of α-MoC support (specific surface area 35 m²) 2 (g) was added to 100 mL of deionized water in a 250 mL round-bottom flask and ultrasonically dispersed for 30 min to obtain a suspension; (2) Add 0.165 g H2PtCl6·6H2O (Pt content 1.0wt%) to the suspension and stir and soak at 80℃ for 6 h; (3) After removing the moisture by rotary evaporation, the resulting solid was dried under vacuum at 110℃ for 12 h; (4) The dried solid was reduced at 350℃ in an atmosphere of H2 / N2 mixed gas (10% H2) for 2 h to obtain the Pt / α-MoC catalyst. It was then naturally cooled to room temperature and stored in an Ar atmosphere.

[0053] Example 2 A method for the reduction, regeneration, and resource utilization of desulfurization waste, used to treat calcium-based fixed-bed desulfurization waste, includes the following steps: (1) Using waste desulfurizing agent generated from calcium-based fixed-bed desulfurization of coke oven gas in a certain coking plant as raw material, the waste desulfurizing agent is crushed and screened to a particle size of 4-5 mm to obtain pretreated waste; wherein, the composition of the waste desulfurizing agent is 45% CaSO4, 30% CaSO3, 20% Ca(OH)2, and 5% impurities; (2) The Pt / α-MoC catalyst prepared in Example 1 was used to catalyze the catalytic cracking reaction of methanol at 180°C to obtain a mixed gas containing carbon monoxide and hydrogen. The mixed gas and nitrogen were mixed at a volume ratio of 1:2 to obtain a mixed reducing gas (composition of CO 11.1%, H2 22.2%, N2 66.7%). The heat source for the catalytic cracking reaction was the hot air (250-350°C) generated during the cooling process of CaO regeneration in step (3). (3) The pretreated waste obtained in step (1) is loaded into a fixed-bed reactor, and the mixed reducing gas obtained in step (2) is introduced. The reaction is carried out at 700°C for 6 h with a reducing gas space velocity of 600 h⁻¹. -1 The process involves reducing the calcium sulfate in the pretreated waste and thermally decomposing the calcium sulfite, yielding a solid product containing calcium oxide and a gaseous product containing sulfur dioxide. The CaO content in the solid product containing calcium oxide is measured to be ≥90%. (4) The calcium oxide-containing solid product obtained in step (3) is cooled to 180°C and then sent to an activation reactor. 0.35 MPa steam is introduced (the steam is introduced for 1.5 h) and a modifier is added (calculated based on the mass of CaO, a composite modifier consisting of 1.5% isopropanol and 1.5% trisodium citrate is added, the modifier is added in two parts, 50% of the composite modifier is added at the initial stage of the reaction, and the remaining composite modifier is added after 45 min of reaction) so that the calcium oxide in the solid product undergoes a hydration reaction to obtain a hydrated product; the hydrated product is heated and dehydrated so that the calcium hydroxide in the hydrated product decomposes into calcium oxide to obtain an activated solid product; the activated solid product is subjected to a second hydration (hydration at 80°C for 1 h) and granulation to obtain a regenerated calcium-based fixed-bed desulfurizer; the desulfurization efficiency test result of the waste desulfurizer is 98.7%; (5) The gaseous product of sulfur dioxide obtained in step (3) is passed into a 20% sodium carbonate solution for absorption reaction to obtain a solution containing sodium bisulfite. The solution containing sodium bisulfite is subjected to dehydration condensation reaction to obtain sodium metabisulfite (purity ≥ 95%).

[0054] Example 3 The difference compared to Example 2 is as follows: In step (1), the waste desulfurizing agent raw material is the waste desulfurizing agent generated from the calcium-based fixed bed desulfurization of the flue gas of the hot blast stove of a steel plant. The composition of the waste desulfurizing agent is 50% CaSO4, 28% CaSO3, 20% Ca(OH)2, 2% iron oxide and dust impurities; the waste desulfurizing agent is crushed and screened to a particle size of 3-4 mm. In step (2), the Pt / α-MoC catalyst prepared in Example 1 is used to carry out a catalytic cracking reaction at 150°C; the heat source for carrying out the catalytic cracking reaction is the hot air (300-400°C) generated during the cooling process of CaO regeneration in step (3). In step (3), the fixed-bed reactor is operated at 750°C for 5 h with a reducing gas hourly space velocity of 500 h⁻¹. -1 The CaO content in the solid product containing calcium oxide was measured to be ≥91%. In step (4), the solid product containing calcium oxide obtained in step (3) is cooled to 190°C; 0.3 MPa of steam is introduced and a modifier is added (calculated based on the mass of CaO, a composite modifier consisting of 1% isopropanol and 2% trisodium citrate is added); the steam is introduced for 1 h; the secondary hydration is carried out at 70°C for 1.5 h; the desulfurization efficiency of the waste desulfurizing agent is measured to be 98.4%.

[0055] Example 4 The difference compared to Example 2 is as follows: In step (1), the waste desulfurizing agent raw material is the waste desulfurizing agent generated from the tail gas desulfurization of a calcium-based fixed bed process in a chemical plant. The composition of the waste desulfurizing agent is 52% CaSO4, 44% CaSO3, 2% Ca(OH)2, and 2% impurities. The waste desulfurizing agent is crushed and screened to a particle size of 4-5 mm. In step (2), the Pt / α-MoC catalyst prepared in Example 1 is used to carry out a catalytic cracking reaction at 190°C; the heat source for carrying out the catalytic cracking reaction is the hot air (200-300°C) generated during the cooling process of CaO regeneration in step (3). In step (3), the fixed-bed reactor reacts at 800℃ for 4 h with a reducing gas space velocity of 500 h⁻¹. -1 The CaO content in the solid product containing calcium oxide was measured to be ≥93%. In step (4), the solid product containing calcium oxide obtained in step (3) is cooled to 170°C; 0.4 MPa of steam is introduced and a modifier is added (calculated based on the mass of CaO, a composite modifier consisting of 2% isopropanol and 1% trisodium citrate is added); the steam is introduced for 2 h; the desulfurization efficiency of the waste desulfurizing agent is measured to be 98.9%.

[0056] Comparative Example 1 Compared with Example 2, the difference is that no modifier was added during the activation process.

[0057] Comparative Example 2 Compared to Example 2, the difference is that the modifier uses 3% isopropanol and does not contain sodium citrate.

[0058] Comparative Example 3 Compared to Example 2, the difference is that the modifier used is 3% sodium citrate and does not contain isopropanol.

[0059] Comparative Example 4 Compared with Example 2, the difference is that step (4) does not involve the CaO activation step, that is, it does not involve the steps of introducing water vapor and using a modifier. Instead, the solid product containing calcium oxide obtained in step (3) is directly hydrated and granulated to obtain a regenerated calcium-based fixed-bed desulfurizer.

[0060] Performance testing The specific surface area of ​​calcium oxide in the solid products of Examples 2-4 before and after activation was tested, and the results are as follows: Figure 2 As shown. Figure 2 The test results showed that the specific surface area of ​​calcium oxide (CaO) in the solid product of Example 2 before and after activation was 8 m². 2 / g、38 m 2 / g, the specific surface area of ​​calcium oxide (CaO) in the solid product of Example 3 before and after activation was 10 m².2 / g、35 m 2 / g, the specific surface area of ​​calcium oxide (CaO) in the solid product of Example 4 before and after activation was 12 m². 2 / g、30 m 2 / g.

[0061] To further evaluate the impact of the activation step, the relationship between the number of desulfurizer regeneration cycles and desulfurization efficiency in Examples 2 and 4 was also tested. The test results are as follows: Figure 3 As shown. Figure 3 This is a graph showing the relationship between the number of regenerated desulfurizing agent cycles and desulfurization efficiency. The horizontal axis represents the number of regeneration cycles, and the vertical axis represents the desulfurization efficiency (%). Figure 3 It can be seen that after steam activation and modification, the desulfurization efficiency of Example 2 is stable at over 98%, while the desulfurization efficiency of Comparative Example 4, which only underwent reduction pyrolysis without activation treatment, is about 85% and decreases with the increase of cycle number.

[0062] To test the effect of the modifier composition on the regenerated desulfurizer, the contact angle of calcium oxide in the solid products of Example 2 and Comparative Examples 1-3 before and after activation was tested. The test conditions are shown in Table 1, and the test results are shown in Table 2.

[0063] Table 1 Test conditions for contact angle

[0064] Table 2. Contact angle test results of Example 2 and Comparative Examples 1-3

[0065] The test results in Table 2 show that, compared with the group without modifier, the contact angle of the composite modifier using isopropanol and trisodium citrate decreased from 89.5° to 18.6°, a reduction of 79%, and the CaO surface changed from "poor hydrophilicity" to "superhydrophilic". Compared with the group using only isopropanol and only trisodium citrate, the composite modifier is more effective and has a synergistic effect, which can synergistically improve the hydrophilicity of the CaO surface.

[0066] Furthermore, the pore structure of calcium oxide in the solid products of Examples 2 and Comparative Examples 1-3 before and after activation was tested, and the test results are shown in Table 3.

[0067] Table 3. Pore structure test results of calcium oxide in the solid products of Example 2 and Comparative Examples 1-3 before and after activation.

[0068] As shown in Table 3, the most probable pore size decreased from 22.4 nm to 8.6 nm (-62%), indicating that the modifier could transform macropores into mesopores, thus refining the pore size. Furthermore, the proportion of micropores <5 nm increased from 8% to 25% (+225%), indicating that the increased number of micropores provides more reactive sites. The proportion of macropores >50 nm decreased from 40% to 8% (-80%), demonstrating a more uniform structure. Table 3 also shows that compared to the group without modifier, the specific surface area using the composite modifier of isopropanol and trisodium citrate increased by 2.54 times, significantly higher than that of isopropanol alone (1.74 times) and trisodium citrate alone (1.59 times).

[0069] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for the reduction, regeneration, and resource utilization of desulfurization waste, characterized in that, The treatment of calcium-based fixed-bed desulfurization waste includes the following steps: Methanol is subjected to catalytic cracking reaction in the presence of a catalyst to obtain a mixed gas containing carbon monoxide and hydrogen. The mixed gas is then mixed with a dilution gas to obtain a mixed reducing gas. Provide calcium-based fixed-bed desulfurization waste containing calcium sulfate and / or calcium sulfite; Under heating conditions, the mixed reducing gas is introduced into the calcium-based fixed bed desulfurization waste, causing the calcium sulfate contained therein to undergo a reduction reaction and the calcium sulfite contained therein to undergo a thermal decomposition reaction, to obtain a solid product containing calcium oxide and a gaseous product containing sulfur dioxide. Steam is introduced into the solid product and a modifier is added to cause the calcium oxide in the solid product to undergo a hydration reaction to obtain a hydrated product. The hydrated product is then heated and dehydrated to decompose the calcium hydroxide in the hydrated product into calcium oxide, thereby obtaining an activated solid product. The activated solid product is then subjected to secondary hydration and granulation to obtain a regenerated calcium-based fixed-bed desulfurizer. The gaseous product is passed into a sodium carbonate solution for absorption reaction to obtain a solution containing sodium bisulfite. The solution containing sodium bisulfite is then subjected to a dehydration condensation reaction to obtain sodium metabisulfite.

2. The method for reduction, regeneration, and resource utilization of desulfurization waste as described in claim 1, characterized in that, In the step of catalytically cracking methanol in the presence of a catalyst to obtain a mixed gas containing carbon monoxide and hydrogen, and then mixing the mixed gas with a dilution gas to obtain a mixed reducing gas: The catalyst is a molybdenum carbide-supported noble metal catalyst, which includes a molybdenum carbide-supported platinum catalyst; and / or, The volume ratio of the mixed gas to the diluent gas is 1:(1~3); and / or, The diluting gas includes nitrogen.

3. The method for reduction, regeneration, and resource utilization of desulfurization waste as described in claim 1, characterized in that, The step of providing calcium-based fixed-bed desulfurization waste containing calcium sulfate and / or calcium sulfite includes: Provide calcium-based fixed-bed desulfurization waste containing calcium sulfate and / or calcium sulfite, and perform crushing and screening to obtain particles of 3-6 mm after screening.

4. The method for reduction, regeneration, and resource utilization of desulfurization waste as described in claim 1, characterized in that, In the step of introducing the mixed reducing gas into the calcium-based fixed-bed desulfurization waste under heating conditions, causing the calcium sulfate contained therein to undergo a reduction reaction and the calcium sulfite contained therein to undergo a thermal decomposition reaction, to obtain a solid product containing calcium oxide and a gaseous product containing sulfur dioxide: The heating temperature is 700~900℃, and the heating time is 2~6 h; and / or, The space velocity of the mixed reducing gas is 500-600 h⁻¹. -1 .

5. The method for reduction, regeneration, and resource utilization of desulfurization waste as described in claim 1, characterized in that, In the step of introducing steam into the solid product and adding a modifier to cause the calcium oxide in the solid product to undergo a hydration reaction to obtain a hydrated product, the modifier includes a first modifier and a second modifier, the first modifier including isopropanol and the second modifier including sodium citrate; and / or, The pressure of the introduced steam is 0.3~0.4 MPa, and the time of introduction is 0.5~2 h; and / or, The modifier is added in multiple stages.

6. The method for reduction, regeneration, and resource utilization of desulfurization waste as described in claim 5, characterized in that, The modifier is added in two stages. The first stage, comprising 40% to 60% of the total mass of the modifier, is added within 0 to 30 minutes after the start of the hydration reaction. The second stage, adding the remaining modifier, is added within 30 to 60 minutes after the completion of the first stage. And / or, The amount of isopropanol added is 1-2% of the mass of calcium oxide, calculated based on the mass of calcium oxide in the solid product. The amount of sodium citrate added is 1-2% of the mass of calcium oxide, calculated based on the mass of calcium oxide in the solid product.

7. The method for reduction, regeneration, and resource utilization of desulfurization waste as described in claim 1, characterized in that, In the step of sequentially subjecting the activated solid product to secondary hydration and granulation to obtain the regenerated calcium-based fixed-bed desulfurizer: The temperature for the secondary hydration is 60~90℃, and the time for the secondary hydration is 0.5~2 h.

8. A system for the reduction, regeneration, and resource utilization of desulfurization waste, characterized in that, The system for treating calcium-based fixed-bed desulfurization waste includes a desulfurization waste pretreatment unit, a reducing gas preparation unit, a fixed-bed reduction-thermal decomposition unit, a regenerated desulfurizing agent production unit, and a sodium metabisulfite production unit; wherein: The desulfurization waste pretreatment unit includes a crushing and screening device, which is used to crush and screen the calcium-based fixed bed desulfurization waste to obtain pretreated waste. The reducing gas preparation unit includes a methanol catalytic cracking reactor, a dilution gas supply device, and a gas mixing device. The methanol catalytic cracking reactor and the dilution gas supply device are respectively connected to the gas mixing device. The methanol catalytic cracking reactor is used to carry out a catalytic cracking reaction of methanol under the action of a catalyst to obtain a mixed gas containing carbon monoxide and hydrogen. The gas mixing device is used to mix the mixed gas containing carbon monoxide and hydrogen with the dilution gas to obtain a mixed reducing gas. The fixed-bed reduction-thermal decomposition unit includes a fixed-bed reactor, a solid product collection device, and a gaseous product collection device. The fixed-bed reactor is connected to the crushing and screening device and the gas mixing device, respectively, to react the pretreated waste with the mixed reducing gas, causing the calcium sulfate in the reactor to undergo a reduction reaction and the calcium sulfite in the reactor to undergo a thermal decomposition reaction, generating a solid product containing calcium oxide and a gaseous product containing sulfur dioxide. The solid product collection device and the gaseous product collection device are connected to the solid outlet and gas outlet of the fixed-bed reactor, respectively. The regenerated desulfurizing agent production unit includes a cooling device, a primary hydration device, a dehydration device, and a secondary hydration device connected in sequence. The cooling device is connected to the solid product collection device and is used to cool the calcium oxide-containing solid product. The primary hydration device is used to perform a primary hydration reaction on the cooled solid product to obtain a first hydrated product. The dehydration device is used to perform a dehydration reaction on the first hydrated product to obtain an activated solid product. The secondary hydration device is used to perform a secondary hydration on the activated solid product, converting the calcium oxide in the activated solid product into calcium hydroxide to obtain a second hydrated product. The sodium metabisulfite production unit includes a sodium metabisulfite reaction device, which is connected to the gas product collection device. The reaction device is used to allow the sulfur dioxide-containing gaseous product to undergo an absorption reaction with the sodium carbonate solution through the sodium metabisulfite reaction device to obtain sodium metabisulfite.

9. The system for the reduction, regeneration, and resource utilization of desulfurization waste as described in claim 8, characterized in that, The regenerated desulfurizer production unit also includes a heat recovery device, which is connected to the cooling device and the methanol catalytic cracking reactor, respectively, and is used to recover the heat during the cooling process of the cooling device and transfer it to the methanol catalytic cracking reactor.

10. The system for the reduction, regeneration, and resource utilization of desulfurization waste as described in claim 8, characterized in that, The regenerated desulfurizing agent production unit also includes a granulation device, which is connected to the secondary hydration device and is used to granulate the second hydration product.

Images