Desulfurizer, preparation method and application thereof

Abstract

The present application relates to the technical field of wet desulfurization technology of coal-fired power plants, and discloses a desulfurizer and a preparation method and application thereof, the desulfurizer provided by the present application comprises, in percentage by mass, limestone, magnesium oxide, diatomite, hydroxyapatite, magnesium aluminum silicate, titanium hydroxyl oxide, poly-aspartic acid calcium chelating agent and an auxiliary agent. The desulfurizer provided by the present application has high activity, high reaction rate, good dispersibility and no obvious agglomeration, and is not prone to block the pipeline during the spraying process. In addition, the activity of the desulfurizer remains stable under the condition of fluctuation of the load of the unit, thereby ensuring long-term stable operation of the desulfurization system, and the desulfurizer can be efficiently adapted to high-sulfur flue gas with a SO2 concentration of 3000 mg / m 3 -5000 mg / m 3 , solves the problem of insufficient reaction of the desulfurizer under high-sulfur flue gas, has high utilization rate of the desulfurizer and high desulfurization efficiency, and the generated gypsum has high purity, uniform particle size and low water content, thereby reducing the disposal cost of solid waste.

Description

Technical Field

[0001] This invention relates to the field of wet desulfurization technology in coal-fired power plants, specifically to a desulfurizing agent, its preparation method, and its application. Background Technology

[0002] The large amount of sulfides released during the combustion of high-sulfur coal can easily cause environmental pollution if they are directly discharged into the atmosphere without treatment. Desulfurization of flue gas after combustion is one of the effective ways to control pollution emissions. Existing methods mainly use a single limestone desulfurizing agent, but there are still many defects: (1) The SO2 concentration in the flue gas is high, and dense calcium sulfite and / or calcium sulfate are easily generated on the surface of limestone particles, which hinders the contact reaction between internal calcium carbonate and SO2, resulting in low utilization rate of limestone particles, low purity of gypsum, low desulfurization efficiency, and difficulty in meeting the standards; (2) The limestone particles have a high density, and the calcium sulfite generated by the reaction is easy to destabilize and flocculate, resulting in calcium sulfite agglomeration and sedimentation. This not only causes gypsum crystallization and breakage, high water content, and inability to be recycled, generating secondary solid waste; it also causes the spray pipe to be blocked and the bottom of the tower to accumulate slurry, increasing the equipment maintenance cost; (3) In order to accelerate the oxidation of calcium sulfite to calcium sulfate, a large amount of oxidation air is forcibly blown in, resulting in high energy consumption. In summary, existing desulfurizing agents generally suffer from problems such as low utilization rate, low desulfurization efficiency, easy agglomeration and sedimentation, poor gypsum quality (low purity, broken crystals, high water content), and high energy consumption. There is an urgent need to develop a desulfurizing agent with high utilization rate, high desulfurization efficiency, no agglomeration and sedimentation, good gypsum quality, and low energy consumption. This is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0003] This invention provides a desulfurizing agent to solve the problems of low utilization rate, low desulfurization efficiency, easy agglomeration and sedimentation, poor gypsum quality, and high energy consumption that are common in existing desulfurizing agents.

[0004] In a first aspect, the present invention provides a desulfurizing agent, wherein the raw material composition of the desulfurizing agent, by mass percentage, comprises: 80wt%-85wt% limestone, 4wt%-6wt% magnesium oxide, 3wt%-5wt% diatomaceous earth, 1wt%-2wt% hydroxyapatite, 1wt%-2wt% magnesium aluminum silicate, 1wt%-2wt% titanium hydroxyl oxide, 1wt%-2wt% calcium polyaspartate chelating agent, and 2wt%-3wt% additives.

[0005] In one optional embodiment, the raw material composition of the desulfurizing agent, by mass percentage, includes: limestone 82wt%-83wt%, magnesium oxide 4.5wt%-5.5wt%, diatomaceous earth 3.5wt%-4.5wt%, hydroxyapatite 1.3wt%-1.7wt%, magnesium aluminum silicate 1.3wt%-1.7wt%, titanium hydroxyl oxide 1.3wt%-1.7wt%, polyaspartic acid calcium chelating agent 1.3wt%-1.7wt%, and additives 1.5wt%-2.5wt%.

[0006] In an optional embodiment, deionized water is also added, wherein the total mass ratio of the limestone, magnesium oxide, diatomaceous earth, hydroxyapatite, magnesium aluminum silicate, titanium hydroxyl oxide, polyaspartic acid calcium chelating agent and additives to the deionized water is 1:1.3-1.4.

[0007] In one alternative embodiment, the adjuvant includes sodium pyrophosphate and sodium carbonate.

[0008] In one optional embodiment, the mass ratio of sodium pyrophosphate to sodium carbonate is 1-3:1.

[0009] In one optional embodiment, the method for preparing the titanium hydroxyl oxide includes: aging metatitanic acid under acidic conditions.

[0010] In one optional embodiment, the aging time is 10-14 hours, and the pH is 5-6.

[0011] In one optional embodiment, the preparation method of the polyaspartic acid calcium chelating agent includes: reacting sodium polyaspartic acid with a calcium salt to obtain the chelating agent.

[0012] In one optional embodiment, the calcium salt, calculated as elemental calcium, has a molar ratio of elemental calcium to sodium polyaspartate of 1.1-1.3:1.

[0013] In one optional embodiment, the method further includes the step of dissolving sodium polyaspartate and calcium salt in water to obtain sodium polyaspartate solution and calcium salt solution, respectively.

[0014] In one optional embodiment, the concentration of the sodium polyaspartate solution is 2wt%-5wt%, and the pH is 8.5-10.5.

[0015] In one optional embodiment, the concentration of the calcium salt solution is 0.5 mol / L to 1 mol / L.

[0016] In one alternative embodiment, the calcium salt includes at least one of calcium chloride and calcium nitrate.

[0017] In one alternative embodiment, the reaction time is 30-40 minutes.

[0018] In an optional embodiment, the method further includes a step of lithium-ion intercalation of the magnesium aluminum silicate.

[0019] In an optional embodiment, the method further includes an acidification step of the diatomaceous earth.

[0020] In one optional embodiment, the limestone contains 90wt%-98wt% CaCO3, has a particle size of 250-330 mesh, and the total content of SiO2 and Al2O3 is ≤5wt%.

[0021] In one optional embodiment, the magnesium oxide has a particle size of 180-220 mesh, a purity of 89%-95%, and an activity of 110 mL / 4 mol·L⁻¹. -1 -150mL / 4mol·L -1 .

[0022] In one optional embodiment, the diatomaceous earth has a specific surface area of ​​120 m². 2 / g-160m 2 / g, with a porosity of 85%-95%.

[0023] In one optional embodiment, the hydroxyapatite has a pore size of 5nm-30nm and a specific surface area of ​​100m². 2 / g-140m 2 / g.

[0024] In a second aspect, the present invention provides a method for preparing the desulfurizing agent described in the first aspect, comprising the following steps: The desulfurizing agent is obtained by mixing the raw materials of the desulfurizing agent.

[0025] Thirdly, the present invention provides an application of the desulfurizing agent described in the first aspect or the desulfurizing agent prepared by the preparation method described in the second aspect in sulfur-containing flue gas.

[0026] The technical solution of this invention has the following advantages: 1. The desulfurizing agent provided by this invention, by mass percentage, comprises the following raw materials: limestone 80wt%-85wt%, magnesium oxide 4wt%-6wt%, diatomaceous earth 3wt%-5wt%, hydroxyapatite 1wt%-2wt%, magnesium aluminum silicate 1wt%-2wt%, titanium hydroxyl oxide 1wt%-2wt%, calcium polyaspartate chelating agent 1wt%-2wt%, and additives 2wt%-3wt%. The desulfurizing agent of this invention exhibits strong activity, high reaction rate, good dispersibility, and no significant agglomeration. It is less likely to clog pipes during spraying, and its activity remains stable under fluctuating unit load conditions, ensuring long-term stable operation of the desulfurization system. It is highly adaptable to SO2 concentrations of 3000 mg / m³. 3 -5000mg / m 3 This method addresses the issue of insufficient desulfurization reaction of high-sulfur flue gas, resulting in high desulfurization agent utilization and efficiency. The generated gypsum is characterized by high purity, uniform particle size, and low moisture content, thereby reducing solid waste disposal costs.

[0027] 2. The desulfurizing agent provided by this invention, in which sodium pyrophosphate and sodium carbonate are combined, can dissociate and release PO4 when dissolved in the desulfurizing agent. 3- CO3 2- PO4 3- With Ca in the slurry 2+ Sodium carbonate forms a soluble complex (Ca2(P2O7)), which slows down the formation rate of CaSO3 and CaSO4 coatings; sodium carbonate can improve the dispersibility of the slurry, reduce the agglomeration of desulfurizing agent particles, increase the contact area between SO2 and desulfurizing agent particles, and thus accelerate the reaction rate. Detailed Implementation

[0028] The following embodiments are provided to better understand the present invention, but the following embodiments do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the scope of protection of the present invention.

[0029] Unless otherwise specified, all experimental steps or conditions in the examples were performed according to conventional experimental procedures and conditions in the art. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0030] Existing methods mainly use a single limestone desulfurizing agent, but still have many drawbacks: (1) SO2 concentration in flue gas ≥ 3000 mg / m³ 3(1) The surface of limestone particles is prone to rapid formation of dense calcium sulfite and / or calcium sulfate, which hinders the contact reaction between internal calcium carbonate and SO2, resulting in low utilization rate of limestone particles (usually ≤75%), low purity of gypsum, low desulfurization efficiency, and difficulty in meeting standards. (2) The high density of limestone particles and the easy destabilization and flocculation of calcium sulfite generated by the reaction lead to calcium sulfite agglomeration and sedimentation, which not only causes gypsum crystallization and breakage, high water content, and inability to be recycled, generating secondary solid waste; it also leads to blockage of spray pipes and slurry accumulation at the bottom of the tower, increasing equipment maintenance costs. (3) In order to accelerate the oxidation of calcium sulfite to calcium sulfate, a large amount of oxidation air is forcibly blown in, resulting in high energy consumption.

[0031] To address the aforementioned problems, in a first aspect, the present invention provides a desulfurizing agent, wherein the raw material composition of the desulfurizing agent, by mass percentage, comprises: 80wt%-85wt% limestone, 4wt%-6wt% magnesium oxide, 3wt%-5wt% diatomaceous earth, 1wt%-2wt% hydroxyapatite, 1wt%-2wt% magnesium aluminum silicate, 1wt%-2wt% titanium hydroxyl oxide, 1wt%-2wt% polyaspartic acid chelated calcium, and 2wt%-3wt% additives.

[0032] In one optional embodiment, the raw material composition of the desulfurizing agent, by mass percentage, includes: limestone 82wt%-83wt%, magnesium oxide 4.5wt%-5.5wt%, diatomaceous earth 3.5wt%-4.5wt%, hydroxyapatite 1.3wt%-1.7wt%, magnesium aluminum silicate 1.3wt%-1.7wt%, titanium hydroxyl oxide 1.3wt%-1.7wt%, polyaspartic acid calcium chelating agent 1.3wt%-1.7wt%, and additives 1.5wt%-2.5wt%.

[0033] In an optional embodiment, deionized water is also added, wherein the total mass ratio of the limestone, magnesium oxide, diatomaceous earth, hydroxyapatite, magnesium aluminum silicate, titanium hydroxyl oxide, polyaspartic acid calcium chelating agent and additives to the deionized water is 1:1.3-1.4.

[0034] It should be noted that the magnesium oxide in this invention is lightly calcined magnesium oxide.

[0035] In one alternative embodiment, the adjuvant includes sodium pyrophosphate and sodium carbonate.

[0036] In one optional embodiment, the mass ratio of sodium pyrophosphate to sodium carbonate is 1-3:1.

[0037] It should be noted that in this invention, the purity of sodium pyrophosphate is ≥99% and the purity of sodium carbonate is ≥98%.

[0038] In one optional embodiment, the method for preparing the titanium hydroxyl oxide includes: first aging metatitanic acid under acidic conditions.

[0039] In one optional implementation, the first aging time is 10-14 hours, and the pH is 5-6.

[0040] Furthermore, sodium hydroxide was used to adjust the pH.

[0041] In one alternative embodiment, prior to the aging of the metatitanic acid, a first reaction is performed between the metatitanic acid and an acidic reagent.

[0042] Furthermore, the first reaction temperature is room temperature, and the time is 25 min-35 min.

[0043] Furthermore, the acidic reagent includes at least one of hydrochloric acid, sulfuric acid, and nitric acid; the concentration of the acidic reagent is 0.4 mol / L to 0.6 mol / L.

[0044] In one optional embodiment, the preparation method of titanium hydroxyl oxide specifically includes: adding metatitanic acid to an acidic reagent, stirring at room temperature, filtering and washing to remove soluble impurities; dispersing the purified metatitanic acid in deionized water at a solid-liquid ratio of 1g:4mL-6mL, adjusting the pH to 5-6 with sodium hydroxide, allowing it to stand at room temperature for hydrolysis and aging, filtering, washing, drying, and grinding through a 200-mesh sieve to obtain titanium hydroxyl oxide.

[0045] It should be noted that after impurity removal, hydrolysis, aging and modification, metatitanic acid mainly consists of TiO(OH)2, Ti(OH)4, and hydroxylated TiO2, which are rich in active hydroxyl groups and are used for rapid adsorption of SO2, buffering of slurry pH, and catalytic oxidation of calcium sulfite.

[0046] In one optional embodiment, the preparation method of the polyaspartic acid calcium chelating agent includes: obtaining it after a second reaction of sodium polyaspartic acid and calcium salt.

[0047] In one optional embodiment, the calcium salt, calculated as elemental calcium, has a molar ratio of elemental calcium to sodium polyaspartate of 1.1-1.3:1.

[0048] In one optional embodiment, the method further includes the step of dissolving sodium polyaspartate and calcium salt in water to obtain sodium polyaspartate solution and calcium salt solution, respectively.

[0049] In one optional embodiment, the concentration of the sodium polyaspartate solution is 2wt%-5wt%, and the pH is 8.5-10.5.

[0050] It should be noted that sodium hydroxide was used to adjust the pH of the sodium polyaspartate solution.

[0051] In one optional embodiment, the concentration of the calcium salt solution is 0.5 mol / L to 1 mol / L.

[0052] In one alternative embodiment, the calcium salt includes at least one of calcium chloride and calcium nitrate.

[0053] In one optional embodiment, the second reaction takes 30-40 minutes.

[0054] In one optional embodiment, the preparation method of the polyaspartic acid calcium chelating agent specifically includes: Sodium polyaspartate (PASP) was dissolved in deionized water, and the pH was adjusted to 8.5-10.5 to obtain a sodium polyaspartate solution. Calcium salt solution was added dropwise at a speed of 1 mL / min-3 mL / min at a rotation speed of 200-250 rpm. After the addition was completed, a second reaction was carried out. The solution was filtered, washed, dried, and pulverized through a 200-mesh sieve to obtain a calcium polyaspartate chelating agent.

[0055] It should be noted that, in this invention, sodium polyaspartate is modified by calcium-based in-situ chelation, which improves the free Ca2+ content. 2+ Forming mild coordination chelation, enabling Ca 2+ It does not release large amounts of gypsum instantaneously, avoiding localized oversaturation and rapid precipitation. At the same time, it inhibits the excessively rapid growth of crystals in a single direction, forming short columnar, equiaxed, dense, and regular gypsum crystals, rather than needle-like, flocculent, or loosely aggregated crystals.

[0056] In an optional embodiment, the method further includes a step of lithium-ion intercalation of the magnesium aluminum silicate.

[0057] In one optional embodiment, the specific steps of lithium-ion intercalation treatment of magnesium aluminum silicate include: preparing a 3wt%-5wt% lithium source solution, mixing magnesium aluminum silicate and the lithium source solution for 40min-60min, drying, pulverizing and passing through a 200-mesh sieve to obtain the solution; the lithium source includes at least one of lithium chloride and lithium carbonate; the ratio of magnesium aluminum silicate to the lithium source solution is 1g:3mL-5mL.

[0058] It should be noted that the lithium-ion intercalated magnesium aluminum silicate has a two-dimensional layered structure, which is used to peel off the gypsum passivation layer and stabilize the slurry suspension.

[0059] In an optional embodiment, the method further includes an acidification step of the diatomaceous earth.

[0060] In one optional embodiment, the diatomaceous earth undergoes an acidification treatment, specifically including the following steps: Diatomaceous earth was mixed with 8wt%-12wt% hydrochloric acid solution, with a liquid-to-solid ratio of 2g-4g:1mL. The mixture was stirred at 45℃-55℃ for 1-3 hours, with stirring every 15-25 minutes for 4-6 minutes each time. The mixture was then washed and dried to obtain the final product.

[0061] In one optional embodiment, the limestone contains 90wt%-98wt% CaCO3, has a particle size of 250-330 mesh, and the total content of SiO2 and Al2O3 is ≤5wt%, with the remainder being impurities. This invention further limits the total content of SiO2 and Al2O3 to ≤5wt%, which can prevent impurities from affecting the reactivity and improve the purity of the gypsum.

[0062] In one optional embodiment, the magnesium oxide has a particle size of 180-220 mesh, preferably 200 mesh, a purity of 89%-95%, and an activity of 110 mL / 4 mol·L⁻¹. -1 -150mL / 4mol·L -1 This invention further limits the activity of magnesium oxide, which can enhance the ability to rapidly absorb SO2.

[0063] It should be noted that the activity of the present invention was obtained by hydrochloric acid titration.

[0064] In one optional embodiment, the diatomaceous earth has a specific surface area of ​​120 m². 2 / g-160m 2 / g, with a porosity of 85%-95%, which can ensure adsorption performance and dispersibility.

[0065] In one optional embodiment, the hydroxyapatite has a pore size of 5nm-30nm and a specific surface area of ​​100m². 2 / g-140m 2 / g.

[0066] It should be noted that, in this invention, the preparation method of hydroxyapatite includes: a fifth reaction of calcium salt solution and phosphate solution, followed by a second aging process.

[0067] Furthermore, the concentration of the calcium salt solution is 0.4 mol / L-0.6 mol / L, and the pH is 9-10.

[0068] Furthermore, the concentration of the phosphate is 0.2 mol / L-0.4 mol / L, and the pH is 9-10.

[0069] Furthermore, the calcium salt includes at least one of calcium nitrate and calcium chloride.

[0070] Furthermore, the phosphate includes at least one of diammonium hydrogen phosphate, diammonium dihydrogen phosphate, and triammonium phosphate.

[0071] Furthermore, the calcium salt is calculated as calcium element, the phosphate is calculated as phosphorus element, and the molar ratio of calcium element to phosphorus element is 1.65-1.7:1.

[0072] Furthermore, the fifth reaction time is 55 min-65 min.

[0073] Furthermore, the second aging temperature is 50℃-60℃, and the time is 8h-10h.

[0074] It should be noted that, in this invention, hydroxyapatite has a large surface area and can be used for targeted capture of SO2 and catalytic oxidation of calcium sulfite.

[0075] In a second aspect, the present invention provides a method for preparing the desulfurizing agent described in the first aspect, comprising the following steps: The desulfurizing agent is obtained by mixing the raw materials of the desulfurizing agent.

[0076] It should be noted that the preparation method of the present invention is simple, the parameters are controllable, no complex equipment is required, and it is compatible with existing wet desulfurization devices. No equipment modification is required, and it can be put into use directly.

[0077] Thirdly, the present invention provides an application of the desulfurizing agent described in the first aspect or the desulfurizing agent prepared by the preparation method described in the second aspect in sulfur-containing flue gas.

[0078] It should be noted that the initial SO2 concentration was 3000 mg / m³. 3 -5000mg / m 3 .

[0079] Example 1 This embodiment provides a method for preparing a desulfurizing agent, including the following steps: (1) The diatomaceous earth was pulverized to 190 mesh, rinsed four times with deionized water to remove surface impurities, dried at 105℃ for 2 hours, cooled, and then mixed with a 10wt% hydrochloric acid solution in a ratio of 3g:1mL. The mixture was stirred in a 50℃ constant temperature water bath for 2 hours, with stirring every 20 minutes for 5 minutes each time. After the reaction was complete, the mixture was washed with deionized water until the pH reached 6.5-7.0, dried at 105℃ for 3 hours, pulverized, and passed through a 200-mesh sieve to obtain modified diatomaceous earth with a specific surface area of ​​140m². 2 / g, porosity 90%; (2) Add 200 mesh magnesium aluminum silicate powder to 4 wt% lithium chloride aqueous solution. The ratio of magnesium aluminum silicate powder to lithium chloride aqueous solution is 1 g: 4 mL. Stir at 200 r / min for 50 min, filter, dry at 70℃ for 2 h, and pulverize through a 200 mesh sieve to obtain lithium-based magnesium aluminum silicate. (3) Prepare 0.5 mol / L calcium nitrate solution and 0.3 mol / L diammonium hydrogen phosphate solution respectively, and adjust the pH of the two solutions to 9-10 using sodium hydroxide; add the diammonium hydrogen phosphate solution dropwise to the calcium nitrate solution at a rate of 3 mL / min according to the molar ratio of Ca to P of 1.67:1, stir at room temperature (250 r / min) for 60 min, then place in a 55℃ water bath for constant temperature aging for 9 h, filter, wash with deionized water until neutral, dry at 80℃, pulverize and pass through a 200 mesh sieve to obtain hydroxyapatite; wherein, the specific surface area of ​​hydroxyapatite is 120 m² / L. 2 / g, with a pore size of 17nm; (4) Add metatitanic acid to 0.5 mol / L dilute hydrochloric acid, stir at room temperature for 30 min, filter and wash to remove soluble impurities; then disperse in deionized water (the ratio of metatitanic acid to deionized water is 1 g: 5 mL), adjust the pH to 5-6 with 3 wt% sodium hydroxide, let stand at room temperature for hydrolysis and aging for 12 h, filter and wash 3 times, dry at 75℃, grind through a 200 mesh sieve to obtain titanium hydroxy oxide; (5) Dissolve sodium polyaspartate in deionized water to obtain a 3wt% sodium polyaspartate solution. Adjust the pH to 8.5-10.5 with sodium hydroxide solution. While stirring (230 r / min), add 0.75 mol / L calcium chloride solution dropwise at 2 mL / min to make the molar ratio of Ca to sodium polyaspartate 1.2:1. After the addition is complete, continue stirring for 35 min. Filter, wash twice, dry at 70℃ for 3 h, and pulverize through a 200 mesh sieve to obtain calcium polyaspartate chelating agent. (6) Add 83wt% limestone powder (CaCO3 content is 95wt%, total content of SiO2 and Al2O3 is 3wt%, particle size is 290 mesh) and 5wt% magnesium oxide (particle size is 200 mesh, purity is 94%, activity is 130mL / 4mol·L) -14 wt% modified diatomaceous earth was added to a high-speed mixer and mixed at 250 r / min for 18 min to ensure uniform mixing. Then, 1.5 wt% lithium-based magnesium aluminum silicate, 1.5 wt% hydroxyapatite, 1.5 wt% titanium hydroxyl oxide, and 1.5 wt% polyaspartic acid calcium chelating agent were added and mixed at 250 r / min for 15 min. Then, sodium pyrophosphate and sodium carbonate were added in a mass ratio of 2:1 and stirred for 12 min. Deionized water was added to the mixer. The mass ratio of the total mass of limestone, magnesium oxide, diatomaceous earth, hydroxyapatite, magnesium aluminum silicate, titanium hydroxyl oxide, polyaspartic acid calcium chelating agent, and additives to deionized water was 1:1.3. The speed was adjusted to 300 r / min and stirred for 25 min to prepare a uniform slurry with a viscosity of 30 mPa·s (25℃), which is the desulfurizing agent.

[0080] Example 2 This embodiment provides a method for preparing a desulfurizing agent, which is basically the same as the steps in Embodiment 1, except that the raw material composition of the desulfurizing agent includes: 82wt% limestone powder, 5.5wt% magnesium oxide, 4.5wt% modified diatomaceous earth, 1.7wt% hydroxyapatite, 1.3wt% lithium-based magnesium aluminum silicate, 1.7wt% titanium hydroxyl oxide, 1.3wt% polyaspartic acid calcium chelating agent, and 2wt% additives.

[0081] Example 3 This embodiment provides a method for preparing a desulfurizing agent, which is basically the same as the steps in Embodiment 1, except that the raw material composition of the desulfurizing agent includes: 83wt% limestone powder, 5wt% magnesium oxide, 3.5wt% modified diatomaceous earth, 1.3wt% hydroxyapatite, 1.7wt% lithium-based magnesium aluminum silicate, 1.3wt% titanium hydroxyl oxide, 1.7wt% polyaspartic acid calcium chelating agent, and 2.5wt% additives.

[0082] Example 4 This embodiment provides a method for preparing a desulfurizing agent, which is basically the same as the steps in Embodiment 1, except that the raw material composition of the desulfurizing agent includes: 80wt% limestone powder, 6wt% magnesium oxide, 4.8wt% modified diatomaceous earth, 1.2wt% hydroxyapatite, 2wt% lithium-based magnesium aluminum silicate, 2wt% titanium hydroxyl oxide, 2wt% polyaspartic acid calcium chelating agent, 2wt% additives, and sodium pyrophosphate and sodium carbonate in a mass ratio of 1:1.

[0083] Example 5 This embodiment provides a method for preparing a desulfurizing agent, which is basically the same as the steps in Embodiment 1, except that the raw material composition of the desulfurizing agent includes: 85wt% limestone powder, 4wt% magnesium oxide, 3wt% modified diatomaceous earth, 2wt% hydroxyapatite, 1wt% lithium-based magnesium aluminum silicate, 1wt% titanium hydroxy oxide, 1wt% polyaspartic acid calcium chelating agent, 3wt% additives, and sodium pyrophosphate and sodium carbonate in a mass ratio of 3:1.

[0084] Example 6 This embodiment provides a method for preparing a desulfurizing agent, which is basically the same as the steps in Embodiment 1, except that step (1) is omitted and the modified diatomaceous earth in step (6) is replaced with diatomaceous earth.

[0085] Example 7 This embodiment provides a method for preparing a desulfurizing agent, which is basically the same as the steps in Embodiment 1, except that step (2) is omitted and the lithium-based magnesium aluminum silicate in step (6) is replaced with magnesium aluminum silicate powder.

[0086] Example 8 This embodiment provides a method for preparing a desulfurizing agent, which is basically the same as the steps in Example 1, except that step (3) is omitted and the hydroxyapatite in step (6) is replaced with hydroxyapatite purchased from Hangzhou Huida Chemical Catalyst Co., Ltd.

[0087] Example 9 This embodiment provides a method for preparing a desulfurizing agent, including the following steps: (1) The diatomaceous earth was pulverized to 190 mesh, rinsed 4 times with deionized water to remove surface impurities, dried at 105℃ for 2 hours, cooled, and then mixed with 8wt% hydrochloric acid solution in a ratio of 4g:1mL. The mixture was stirred in a 55℃ constant temperature water bath for 3 hours, with stirring every 25 minutes for 4 minutes each time. After the reaction was completed, the mixture was washed with deionized water until the pH reached 6.5-7.0, dried at 105℃ for 3 hours, pulverized, and passed through a 200-mesh sieve to obtain modified diatomaceous earth with a specific surface area of ​​130m². 2 / g, porosity 87%; (2) Add 200 mesh magnesium aluminum silicate powder to 5 wt% lithium chloride aqueous solution. The ratio of magnesium aluminum silicate powder to lithium chloride aqueous solution is 1 g: 5 mL. Stir at 200 r / min for 40 min, filter, dry at 70℃ for 2 h, and pulverize through a 200 mesh sieve to obtain lithium-based magnesium aluminum silicate. (3) Prepare 0.6 mol / L calcium chloride solution and 0.4 mol / L ammonium dihydrogen phosphate solution respectively, and adjust the pH of the two solutions to 9-10 using sodium hydroxide; add the ammonium dihydrogen phosphate solution dropwise to the calcium chloride solution at a rate of 3 mL / min according to the molar ratio of Ca to P of 1.65:1, stir at room temperature (250 r / min) for 55 min, then place in a 60℃ water bath for constant temperature aging for 8 h, filter, wash with deionized water until neutral, dry at 80℃, pulverize and pass through a 200 mesh sieve to obtain hydroxyapatite; wherein, the specific surface area of ​​hydroxyapatite is 110 m² / L. 2 / g, with a pore size of 23nm; (4) Add metatitanic acid to 0.4 mol / L dilute nitric acid, stir at room temperature for 35 min, filter and wash to remove soluble impurities; then disperse in deionized water (the ratio of metatitanic acid to deionized water is 1 g: 4 mL), adjust the pH to 5-6 with 3 wt% sodium hydroxide, let stand at room temperature for hydrolysis and aging for 14 h, filter and wash 3 times, dry at 75℃, grind through a 200 mesh sieve to obtain titanium hydroxy oxide; (5) Dissolve sodium polyaspartate in deionized water to obtain a 2wt% sodium polyaspartate solution. Adjust the pH to 8.5-10.5 with sodium hydroxide solution. While stirring (200 r / min), add 0.5 mol / L calcium chloride solution dropwise at 3 mL / min to make the molar ratio of Ca to sodium polyaspartate 1.3:1. After the addition is complete, continue stirring for 30 min. Filter and wash twice, dry at 70℃ for 3 h, and pulverize through a 200 mesh sieve to obtain calcium polyaspartate chelating agent. (6) Add 83wt% limestone powder (CaCO3 content is 97wt%, total content of SiO2 and Al2O3 is 1wt%, particle size is 330 mesh) and 5wt% lightly calcined magnesia (particle size is 220 mesh, purity is 89%, activity is 110mL / 4mol·L) -1 4 wt% modified diatomaceous earth was added to a high-speed mixer and mixed at 250 r / min for 18 min to ensure uniform mixing. Then, 1.5 wt% lithium-based magnesium aluminum silicate, 1.5 wt% hydroxyapatite, 1.5 wt% titanium hydroxyl oxide, and 1.5 wt% polyaspartic acid calcium chelating agent were added and mixed at 250 r / min for 15 min. Then, sodium pyrophosphate and sodium carbonate were added in a mass ratio of 2:1 and stirred for 12 min. Deionized water was added to the mixer. The mass ratio of the total mass of limestone powder, magnesium oxide, modified diatomaceous earth, hydroxyapatite, lithium-based magnesium aluminum silicate, titanium hydroxyl oxide, polyaspartic acid calcium chelating agent, and additives to deionized water was 1:1.35. The speed was adjusted to 300 r / min and stirred for 25 min to prepare a uniform slurry with a viscosity of 25 mPa·s (25℃), which is the desulfurizing agent.

[0088] Example 10 This embodiment provides a method for preparing a desulfurizing agent, including the following steps: (1) The diatomaceous earth was pulverized to 190 mesh, rinsed four times with deionized water to remove surface impurities, dried at 105℃ for 2 hours, cooled, and then mixed with a 12wt% hydrochloric acid solution in a ratio of 2g:1mL. The mixture was stirred in a 45℃ constant temperature water bath for 1 hour, with stirring every 15 minutes for 6 minutes each time. After the reaction was complete, the mixture was washed with deionized water until the pH reached 6.5-7.0, dried at 105℃ for 3 hours, pulverized, and passed through a 200-mesh sieve to obtain modified diatomaceous earth with a specific surface area of ​​150m². 2 / g, porosity 92%; (2) Add 200 mesh magnesium aluminum silicate powder to 3 wt% lithium chloride aqueous solution. The ratio of magnesium aluminum silicate powder to lithium chloride aqueous solution is 1 g: 3 mL. Stir at 200 r / min for 60 min, filter, dry at 70℃ for 2 h, and pulverize through a 200 mesh sieve to obtain lithium-based magnesium aluminum silicate. (3) Prepare 0.4 mol / L calcium nitrate solution and 0.2 mol / L triammonium phosphate solution respectively, and adjust the pH of the two solutions to 9-10 using sodium hydroxide; add the triammonium phosphate solution dropwise to the calcium nitrate solution at a rate of 3 mL / min according to the molar ratio of Ca to P of 1.7:1, stir at room temperature (250 r / min) for 65 min, then place in a 50℃ water bath for constant temperature aging for 10 h, filter, wash with deionized water until neutral, dry at 80℃, pulverize and pass through a 200 mesh sieve to obtain hydroxyapatite; wherein, the specific surface area of ​​hydroxyapatite is 130 m² / L. 2 / g, with a pore size of 11nm; (4) Add metatitanic acid to 0.6 mol / L dilute sulfuric acid, stir at room temperature for 25 min, filter and wash to remove soluble impurities; then disperse in deionized water (the ratio of metatitanic acid to deionized water is 1 g: 6 mL), adjust the pH to 5-6 with 3 wt% sodium hydroxide, let stand at room temperature for hydrolysis and aging for 10 h, filter and wash 3 times, dry at 75℃, grind through a 200 mesh sieve to obtain titanium hydroxy oxide; (5) Dissolve sodium polyaspartate in deionized water to obtain a 5wt% sodium polyaspartate solution. Adjust the pH to 8.5-10.5 with sodium hydroxide solution. While stirring (250 r / min), slowly add 1 mol / L calcium nitrate solution to make the molar ratio of Ca to sodium polyaspartate 1.1:1. After the addition is complete, continue stirring for 40 min. Filter and wash twice, dry at 70℃ for 3 h, and pulverize through a 200 mesh sieve to obtain calcium polyaspartate chelating agent. (6) Add 83wt% limestone powder (CaCO3 content is 90wt%, total SiO2 and Al2O3 content is 3wt%, particle size is 250 mesh) and 5wt% lightly calcined magnesia (particle size is 180 mesh, purity is 95%, activity is 149mL / 4mol·L) -1 4 wt% modified diatomaceous earth was added to a high-speed mixer and mixed at 250 r / min for 18 min to ensure uniform mixing. Then, 1.5 wt% lithium-based magnesium aluminum silicate, 1.5 wt% hydroxyapatite, 1.5 wt% titanium hydroxyl oxide, and 1.5 wt% polyaspartic acid calcium chelating agent were added and mixed at 250 r / min for 15 min. Then, sodium pyrophosphate and sodium carbonate were added in a mass ratio of 2:1 and stirred for 12 min. Deionized water was added to the mixer. The mass ratio of the total mass of limestone, magnesium oxide, diatomaceous earth, hydroxyapatite, magnesium aluminum silicate, titanium hydroxyl oxide, polyaspartic acid calcium chelating agent, and additives to deionized water was 1:1.4. The speed was adjusted to 300 r / min and stirred for 25 min to prepare a uniform slurry with a viscosity of 20 mPa·s (25℃), which is the desulfurizing agent.

[0089] Comparative Example 1 This comparative example provides a method for preparing a desulfurizing agent, which is basically the same as the steps in Example 1, except that the polyaspartic acid calcium chelating agent in Example 1 is replaced with limestone of the same mass content.

[0090] Comparative Example 2 This comparative example provides a method for preparing a desulfurizing agent, which is basically the same as the steps in Example 1, except that the titanium hydroxyl oxide in Example 1 is replaced with metatitanic acid of the same mass content.

[0091] Experimental Example 1 Using the absorption tower described in Chinese patent document CN108554145A, the desulfurizing agents prepared in Examples 1-10 and Comparative Examples 1-2 were subjected to a flue gas temperature of 120±5℃ and an initial SO2 concentration of 3500 mg / m³. 3 -4000mg / m 3 The liquid-to-gas mass ratio is 12 L / m³ 3 Under the condition of setting up 4 layers of spraying, and with single limestone as the control group, the desulfurization effect was tested after 72 hours of cyclic use. The results are shown in Table 1; specifically: Utilization rate: refers to the ratio of the molar amount of effective calcium and magnesium components in the desulfurizing agent participating in the desulfurization reaction to the total molar amount of effective calcium and magnesium components in the desulfurizing agent before desulfurization, expressed as a mass percentage; the effective calcium and magnesium components are alkaline active components such as CaCO3 and MgO in the desulfurizing agent that can react with SO2. 1 mol of SO2 corresponds to the consumption of 1 mol of CaCO3 or 1 mol of MgO, and the reaction consumption is calculated accordingly; After the experiment, a small amount of slurry and the desulfurizing agent prepared in the example were collected from the tower. The samples were filtered, dried, and ground to obtain solid samples after the reaction. Solid samples m (1.0000 g each) were accurately weighed, dissolved in hydrochloric acid solution by heating, and diluted to a 250 mL volumetric flask. 25 mL of the sample solution was transferred, and triethanolamine masking agent and sodium hydroxide solution were added to adjust the pH to ≥12. A calcium indicator was added, and the solution was titrated to the endpoint with EDTA standard solution. The total molar amount n of total effective calcium (calculated as CaO) and total effective magnesium (calculated as MgO) in the sample was calculated. Simultaneously, the total molar amount nSO2 of SO2 cumulatively removed throughout the experiment was calculated using online data from a flue gas analyzer. This verified the matching between the effective calcium and magnesium molar amounts consumed in the reaction (ntotal - nremaining) and nSO2, with a deviation ≤1%. The utilization rate is calculated as follows: ω = (ntotal - nremaining) / ntotal × 100%; where ntotal is the total molar amount of effective calcium and magnesium components in the desulfurizing agent, in mol; and nremaining is the total molar amount of effective calcium and magnesium components remaining after the desulfurization reaction, in mol.

[0092] Desulfurization efficiency: Desulfurization efficiency is calculated based on the measured SO2 concentration in the flue gas at the inlet and outlet of the desulfurization tower at the same time point. It characterizes the desulfurizing agent's ability to remove SO2 from the flue gas, expressed as a mass percentage. Desulfurization efficiency calculation formula: η = (Cin Cout) / Cin×100%; where η is the desulfurization efficiency, in %; and Cin is the converted SO2 concentration at the inlet of the desulfurization tower (SO2 concentration under 6% oxygen) at the same time point, in mg / m³. 3 Cout represents the converted SO2 concentration at the desulfurization tower outlet at the same time point, in mg / m³. 3 .

[0093] SO2 concentration at outlet: A high-precision constant potential electrolysis flue gas analyzer, certified by the national metrology department, was used. The instrument resolution is ≤1 mg / m³. 3 SO2 detection range 0-10000 mg / m³ 3 The indication error is ≤ ±2% of full scale. The sampling probe of the flue gas analyzer is fixed to the straight pipe section of the flue gas outlet of the desulfurization tower (the sampling points are all set in the pipe section with stable flow velocity, no eddies, and no air leakage), and the outlet SO2 concentration data is continuously collected throughout the process.

[0094] Table 1. Test results of the desulfurization effect of the desulfurizing agents prepared in each embodiment and comparative example.

[0095] As shown in Table 1, the desulfurizing agents prepared in Examples 1-10 had a utilization rate of 93.3%-96.4%, a desulfurization efficiency of 98.8%-99.7%, and an average outlet SO2 concentration of 12 mg / m³. 3-25mg / m 3 Comparative Example 1 omits the addition of polyaspartic calcium chelating agent. The main function of polyaspartic calcium chelating agent is to chelate free Ca. 2+ The effect of regulating gypsum crystallization is mainly on gypsum, a byproduct of desulfurization, and has little impact on desulfurization efficiency and utilization rate. In Comparative Example 2, when titanium hydroxyl oxide was replaced with metatitanic acid of the same mass content, the utilization rate of the desulfurizing agent, the desulfurization efficiency, and the average concentration of SO2 at the outlet were all poor.

[0096] Experimental Example 2 The purity, particle size, and moisture content of the gypsum obtained after desulfurization in Examples 1-10, Comparative Examples 1-2, and the control group were tested, and the results are shown in Table 2; specifically: Purity: The purity of gypsum was tested using the water of crystallization method; Particle size: The particle size was measured using a laser particle size analyzer. Moisture content: Free water is removed by low-temperature drying, and the mass loss is calculated.

[0097] Table 2 Results of gypsum performance tests

[0098] As shown in Table 2, the gypsum obtained after desulfurization in this invention has a high purity of 95.2%-97.8%, a particle size of 0.13mm-0.29mm, and a moisture content of 5%-12%, indicating high gypsum quality. In contrast, Comparative Example 1 omitted the addition of polyaspartic acid calcium chelating agent, and Comparative Example 2 replaced titanium hydroxyl oxide with the same mass content of metatitanic acid, resulting in poorer gypsum quality.

[0099] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A desulfurizing agent, characterized in that, The raw material composition of the desulfurizing agent, by mass percentage, includes: limestone 80wt%-85wt%, magnesium oxide 4wt%-6wt%, diatomaceous earth 3wt%-5wt%, hydroxyapatite 1wt%-2wt%, magnesium aluminum silicate 1wt%-2wt%, titanium hydroxyl oxide 1wt%-2wt%, calcium polyaspartate chelating agent 1wt%-2wt%, and additives 2wt%-3wt%.

2. The desulfurizing agent according to claim 1, characterized in that, The desulfurizing agent comprises, by weight percentage: limestone 82wt%-83wt%, magnesium oxide 4.5wt%-5.5wt%, diatomaceous earth 3.5wt%-4.5wt%, hydroxyapatite 1.3wt%-1.7wt%, magnesium aluminum silicate 1.3wt%-1.7wt%, titanium hydroxyl oxide 1.3wt%-1.7wt%, calcium polyaspartate chelating agent 1.3wt%-1.7wt%, and additives 1.5wt%-2.5wt%. And / or, it also includes the addition of deionized water, wherein the total mass ratio of the limestone, magnesium oxide, diatomaceous earth, hydroxyapatite, magnesium aluminum silicate, titanium hydroxyl oxide, polyaspartic acid calcium chelating agent and additives to the deionized water is 1:1.3-1.

4.

3. The desulfurizing agent according to claim 1 or 2, characterized in that, The additives include sodium pyrophosphate and sodium carbonate; Optionally, the mass ratio of sodium pyrophosphate to sodium carbonate is 1-3:

1.

4. The desulfurizing agent according to claim 1 or 2, characterized in that, The method for preparing the titanium hydroxyl oxide includes: aging metatitanic acid under acidic conditions; Optionally, the aging time is 10-14 hours, and the pH is 5-6.

5. The desulfurizing agent according to claim 1 or 2, characterized in that, The preparation method of the polyaspartic acid calcium chelating agent includes: reacting sodium polyaspartic acid with calcium salt to obtain it.

6. The desulfurizing agent according to claim 5, characterized in that, The calcium salt, calculated as elemental calcium, has a molar ratio of elemental calcium to sodium polyaspartate of 1.1-1.3:

1. And / or, it also includes the step of dissolving sodium polyaspartate and calcium salt in water to obtain sodium polyaspartate solution and calcium salt solution, respectively; And / or, the concentration of the polyaspartic acid sodium solution is 2wt%-5wt%, and the pH is 8.5-10.5; And / or, the concentration of the calcium salt solution is 0.5 mol / L to 1 mol / L; And / or, the calcium salt includes at least one of calcium chloride and calcium nitrate; And / or, the reaction time is 30 min-40 min.

7. The desulfurizing agent according to claim 1 or 2, characterized in that, It also includes a step of lithium-ion intercalation treatment of the magnesium aluminum silicate; And / or, it also includes the step of acidifying the diatomaceous earth.

8. The desulfurizing agent according to claim 1 or 2, characterized in that, The limestone contains 90wt%-98wt% CaCO3, has a particle size of 250-330 mesh, and the total content of SiO2 and Al2O3 is ≤5wt%. And / or, the magnesium oxide has a particle size of 180-220 mesh, a purity of 89%-95%, and an activity of 110 mL / 4 mol·L⁻¹. -1 -150mL / 4mol·L -1 ; And / or, the specific surface area of ​​the diatomaceous earth is 120 m². 2 / g-160m 2 / g, porosity 85%-95%; And / or, the hydroxyapatite has a pore size of 5nm-30nm and a specific surface area of ​​100m². 2 / g-140m 2 / g.

9. A method for preparing the desulfurizing agent according to any one of claims 1-8, characterized in that, Includes the following steps: The desulfurizing agent is obtained by mixing the raw materials of the desulfurizing agent.

10. The application of the desulfurizing agent according to any one of claims 1-8 or the desulfurizing agent prepared by the preparation method according to claim 9 in sulfur-containing flue gas.

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