Desulfurization synergistic coking, slagging and ash deposition inhibitor as well as preparation method and application thereof

Abstract

The invention provides a desulfurization synergistic coking, slagging and ash deposition inhibitor as well as a preparation method and application thereof. The inhibitor comprises the following raw materials in parts by mass: 55-80 parts of a desulfurizing agent, 1-3 parts of a denitrifying agent, 8-20 parts of a coal saving agent, 3-10 parts of an alkali fixing agent, 8-20 parts of a slag and ash inhibiting agent and 8-15 parts of a modified coking reinforcing agent, wherein the modified coking reinforcing agent is formed by taking mineral powder as a core body and Mg / Al composite metal nanosheets as a shell layer; the modified coking enhancer takes into account the multi-effect synergistic effect of slag inhibition, ash inhibition, alkali solidification and assistant desulfurization and denitrification by virtue of the dual functions of an Mg structural framework and an Al alkali solidification metal, has the advantages of low cost, high stability and balanced effect, is an upgraded scheme of a traditional single mineral or salt additive, and is used for synergistically improving the slag and ash inhibition effect with a slag and ash inhibitor, so that the modified coking enhancer has a wide application prospect. And obvious advantages can be embodied under the condition of adding a small amount.

Description

Technical Field

[0001] This invention relates to the fields of environmental protection and new materials technology, and in particular to a desulfurization-enhancing coking, slag, and ash accumulation inhibitor, its preparation method, and its application. Background Technology

[0002] With the continuous advancement of national energy conservation and emission reduction policies and increasingly stringent environmental standards, pollutants emitted by coal-fired industrial boilers and coal-fired power generating units during operation have gradually become a key focus of regulation. Among these, sulfur dioxide (SO2) and nitrogen oxides (NOx) are particularly important. x Pollutants are a major precursor to acid rain and smog. Meanwhile, coking, slagging, and ash accumulation on boiler heating surfaces severely impact heat transfer efficiency and operational safety, leading to decreased boiler efficiency, increased fuel consumption, and higher maintenance frequency. How to achieve efficient pollutant control and improved operational efficiency while ensuring stable boiler operation has become a critical issue that the industry urgently needs to address.

[0003] Existing desulfurization and denitrification technologies mainly include flue gas desulfurization (FGD), selective non-catalytic reduction (SNCR), and selective catalytic reduction (SCR). Although these technologies can reduce pollutant emissions to a certain extent, they still have the following shortcomings: (1) High investment and operating costs, especially for SCR systems which require a large amount of catalyst and high operating and maintenance costs; (2) Some methods have strict requirements on reaction temperature, limiting their applicability; (3) Byproducts or side reactions may lead to equipment corrosion and wear, shortening boiler life; (4) Relying solely on end-of-pipe treatment cannot suppress the generation of pollutants from the combustion process itself, and it is also difficult to solve the problems of coking and ash accumulation.

[0004] In terms of combustion process control, the industry has attempted to capture SO2 in the furnace and improve ash characteristics by adding limestone, lime, magnesium-based minerals, or composite additives. However, traditional limestone or single mineral powders suffer from insufficient reactivity, low utilization, and severe particle loss, resulting in limited desulfurization efficiency. Furthermore, conventional mineral additives are not significantly effective in addressing the common boiler problems of coking, slagging, and ash accumulation; they may even form low-melting-point salts under certain conditions, exacerbating the slagging risk. Therefore, existing additive technologies struggle to achieve an integrated, cost-effective solution for desulfurization, slag suppression, ash reduction, coal saving, and auxiliary denitrification.

[0005] In recent years, magnesium-based composite minerals have attracted attention due to their high high-temperature reactivity and neutralization effect on acidic oxides. Magnesium can effectively increase the melting temperature of ash and slag, reduce the formation of low-melting-point phases, thereby inhibiting coking on heated surfaces and slagging in the furnace. At the same time, magnesium-based substances react with sulfur oxides at high temperatures to form stable magnesium sulfate or calcium sulfate composite phases, which have a synergistic effect on desulfurization in the furnace.

[0006] Therefore, there is an urgent need to develop a novel combustion additive based on minerals such as dolomite powder and magnesite powder, which constructs an active shell through surface modification or composite formation. This additive can not only efficiently capture SO2 and improve desulfurization efficiency during combustion in the furnace, but also significantly increase the ash melting point, inhibit coking and ash formation, help reduce nitrogen oxide emissions, and save coal consumption by improving heat transfer and combustion efficiency. Thus, it provides an efficient, economical, and environmentally friendly comprehensive treatment technology for industrial boilers and coal-fired power plants. Summary of the Invention

[0007] Objective of this invention: The objective of this invention is to provide a desulfurization-enhancing inhibitor for coking, slag formation, and ash accumulation, its preparation method, and its application. By introducing a metal composite shell onto the surface of traditional calcium-based mineral powders (such as dolomite powder and heavy calcium carbonate), not only can the specific surface area and high-temperature activity of the powder be increased, but its dispersibility and reaction efficiency in pulverized coal combustion environments can also be improved. By controlling the shell ratio, the molar ratio of the composite metal, the particle size distribution, and the addition location, the optimal reaction effect of the additive under industrial boiler and power plant operating conditions can be achieved.

[0008] The technical solution of the present invention:

[0009] In a first aspect, the present invention provides a desulfurization-enhancing coking, slag, and ash accumulation inhibitor; the raw materials for the inhibitor, by mass parts, include:

[0010]

[0011] The modified coking enhancer is composed of mineral powder as the core and Mg / Al composite metal nanosheets as the shell.

[0012] In some embodiments, the Mg / Al composite metal nanosheets are porous sheet structures formed by stacking layers.

[0013] In some embodiments, the molar ratio of Mg to Al in the Mg / Al composite metal nanosheets is 3-8:1.

[0014] The mineral powder core material is dense and has high mechanical strength, providing a stable substrate for the outer layer and providing the main desulfurization capability. The transition layer, as a "substrate," improves the adhesion between the shell and the core layer and can decompose into MgO at high temperatures, thus having the functions of slag suppression and increasing the ash melting point. The shell provides a high specific surface area and active sites, and decomposes at high temperatures, transforming into a MgO-Al2O3 dispersed phase, which can react with K / Na to generate a high-melting-point composite salt, inhibiting slag formation. It also maintains a certain porosity, which is conducive to gas diffusion and SO2 contact.

[0015] In some embodiments, the desulfurizing agent is selected from one or more combinations of oxalic acid, glutaric acid, succinic acid, or potassium permanganate.

[0016] In some embodiments, the denitrifying agent is selected from one or more combinations of sodium chlorite, urea, melamine monoamide, cyanuric acid monoamide, or cyanuric acid diamide.

[0017] In some embodiments, the coal-saving agent is selected from one or more combinations of barium nitrate or borax.

[0018] In some embodiments, the alkali-fixing agent is selected from one or more combinations of calcined kaolin, high-alumina fly ash, ammonium dihydrogen phosphate, and monoammonium phosphate. Calcined kaolin, metakaolin, and high-alumina fly ash can provide a silicon source, which can form high-melting-point aluminosilicates with K / Na; ammonium dihydrogen phosphate and monoammonium phosphate can provide a phosphorus source, which can further fix K / Na.

[0019] In some embodiments, the slag and ash suppressant is selected from one or more combinations of light-burned magnesia powder or brucite powder. It forms ultrafine MgO in situ at high temperatures, increasing the MgO content and skeleton strength at high temperatures, and synergistically enhances the slag and coke suppression effect with the modified coking enhancer.

[0020] In some embodiments, the preparation method of the modified coking enhancer includes the following steps:

[0021] The nucleus powder is slurryed, Mg and Al sources are added, the pH is adjusted to alkaline, and the mixture is heated and aged to allow Mg and Al to form heterogeneous nuclei on the nucleus surface. After washing, drying and pre-activation, a modified coking enhancer is obtained.

[0022] In some embodiments, the core powder is one or more combinations of dolomite powder, heavy calcium carbonate powder, calcite powder, apatite powder, or seaweed calcium powder.

[0023] In some embodiments, the Mg source is selected from one or more combinations of magnesite powder, lightly calcined magnesia powder, or brucite powder.

[0024] In some embodiments, the Al source is selected from one or more combinations of calcined kaolin, alunite, montmorillonite, chlorite, and orthoclase.

[0025] In some embodiments, alkalinity refers to a pH of 10-10.5, and heating aging refers to heating to 50-65°C and aging for 60-120 minutes.

[0026] In some embodiments, the drying pre-activation refers to drying at 110°C and then lightly activating at 200-250°C for 0.5-1 h.

[0027] In a second aspect, the present invention provides a method for preparing the desulfurization-enhancing coking, slag-forming, and ash-accumulating inhibitor, specifically comprising weighing the corresponding raw materials according to the above formula, adding them to a powder mixer for uniform mixing, and obtaining the coking, slag-forming, and ash-accumulating inhibitor.

[0028] In a third aspect, the present invention provides the application of the desulfurization-enhancing coking, slag-forming, and ash-accumulating inhibitor in coal-fired industrial boilers / power plants.

[0029] In some embodiments, the application includes adding a coking, slagging, and ash-accumulating inhibitor to the fuel before combustion, at a ratio of 0.4-1 wt% of the total fuel weight.

[0030] Beneficial effects:

[0031] 1. Coking, slag, and ash inhibitors can significantly improve the reaction rate and utilization rate of mineral powder. In particular, the modified coking enhancer added to it can achieve a higher desulfurization / slag suppression effect under the same dosage.

[0032] 2. The modified coking enhancer uses inexpensive mineral powder as its core and only constructs a composite metal shell on the surface, resulting in low preparation cost.

[0033] 3. Coking, slag, and ash accumulation inhibitors achieve integrated desulfurization, slag suppression, ash accumulation suppression, and auxiliary denitrification, rather than single-end treatment, enabling synergistic control of multiple pollutants. They also work in conjunction with desulfurizing and denitrification agents to achieve better treatment results. Detailed Implementation

[0034] The present invention will be described below with reference to specific embodiments. It should be noted that the following embodiments are examples of the present invention and are used only to illustrate the invention, not to limit it. Other combinations and various modifications within the scope of the present invention can be made without departing from its spirit or scope.

[0035] Unless otherwise specified, all chemical reagents used in this invention are commercially available analytical grade reagents.

[0036] Preparation of modified coking enhancer 1

[0037] Add 300g of deionized water to the reactor and heat to 55℃. Add 85g of dolomite powder, start stirring at 120rpm, circulate and disperse for 20 minutes, adjust the pH to 10 with ammonia water to form a uniform nucleus powder slurry.

[0038] Add 85g of lightly calcined magnesium powder to 300g of deionized water and disperse by circulation to obtain a Mg source slurry. Add the Mg source slurry to the nuclear powder slurry, and maintain the reactor temperature at 55℃ and pH at 10.0. Circulate and disperse for 10 minutes.

[0039] Add 90g of calcined kaolin to 600g of deionized water and disperse it into a fine suspension at 1200rpm under high shear. Add this suspension to the mixture, maintaining a shear rate of 350rpm during the addition process. Heat to 65℃ and maintain the temperature at 10.5. After complete addition and uniform dispersion, age the mixture for 4 hours while maintaining the same shear rate, temperature, and pH. After aging, allow it to cool naturally to room temperature, wash the solid, and dry it at 110℃ to constant weight until the conductivity is ≤100μS / cm. Then, reheat to 230℃ for 1 hour for mild heat treatment to activate the powder.

[0040] The dry powder was atomized and sprayed with a 2wt% PVA solution, and granulated using a spray / disc granulator with a target D50 of 50 μm. It was then dried at 90℃ until the moisture content was ≤0.3%, and sieved to 100 μm to obtain modified coking enhancer 1.

[0041] In the modified coking enhancer 1, the Mg / Al ratio is 2.1:0.7 = 3.

[0042] Preparation of modified coking enhancer 2

[0043] The preparation steps are basically the same as those for preparing modified coking reinforcing agent 1, except that the amount of lightly calcined magnesium powder added is 120g and the amount of calcined kaolin added is 57g.

[0044] The Mg / Al ratio in modified coking enhancer 2 is 2.98:0.5 = 5.9.

[0045] Preparation of modified coking enhancer 3

[0046] The preparation steps are basically the same as those for preparing modified coking reinforcing agent 1, except that the amount of lightly calcined magnesium powder added is 130g and the amount of calcined kaolin added is 50g.

[0047] The Mg / Al ratio in modified coking enhancer 3 is 3.2:0.44 = 7.3.

[0048] Preparation of modified coking enhancer 4

[0049] The preparation steps are basically the same as those for preparing modified coking agent 1, except that the amount of lightly calcined magnesium powder added is 0g.

[0050] Preparation of modified coking enhancer 5

[0051] The preparation steps are basically the same as those for preparing modified coking reinforcing agent 1, the only difference being that the amount of calcined kaolin added is 0g.

[0052] Example

[0053] According to the formula in Table 1, weigh the raw materials and add them to the powder mixer for uniform mixing to obtain the coking, slag, and ash accumulation inhibitor.

[0054] Table 1. Formulations for Examples (Unit: Parts by Mass)

[0055]

[0056] Comparative Example

[0057] According to the formula in Table 2, weigh the raw materials and add them to the powder mixer for uniform mixing to obtain the inhibitor.

[0058] Table 2 Comparative Example Formulations (Unit: Parts by Mass)

[0059]

[0060]

[0061] The samples prepared in the examples and comparative examples were tested according to the following steps, and the results are shown in Table 3 below.

[0062] Coal sample: Medium sulfur, medium alkali metal coal (K2O in ash ≈ 1.5 ± 0.5 wt%).

[0063] 1. Ash fusion test: Prepare ash samples. For each group, prepare 50g of pulverized coal + 0.5w% of coking, slag, and ash accumulation inhibitor, thoroughly dry mix for 5min, and burn in a muffle furnace at 815±10℃ for 1h to obtain bottom ash. Weigh and record the weight loss. In the fusion test furnace, increase the temperature at 5℃ / min from 900℃ to 1500℃, and record the specimen deformation using a camera system. Record HT (hemispherical temperature).

[0064] 2. Probe deposition test: The test device uses a controllable temperature probe to stably heat at 800℃, with a powder delivery rate of 10g / h and a gas velocity of 5m / s. The probe is weighed before and after operation (accuracy 0.1mg), and the deposition amount is recorded.

[0065] 3. Alkali metal solidification rate: A small fluidized bed was used to burn a sample of coal (50g pulverized coal + 0.5w% coking, slagging, and ash-accumulating inhibitor) at 1000℃. Fly ash and bottom ash were collected. Water-soluble extraction was performed on the fly ash (1g fly ash was weighed, shaken with 50mL deionized water for 30min, centrifuged, and the supernatant was collected). The water-soluble potassium content was determined. + Calculate the fixed rate.

[0066] 4. Denitrification test: The small furnace is equipped with an online NO / NO2 measuring instrument. After 10 minutes of steady-state operation, the denitrification efficiency of NO and NO2 is recorded.

[0067] Table 3

[0068]

[0069]

[0070] The modified coking enhancer, with its layered structure, decomposes at low temperatures to release water / CO2 and form highly dispersed MgO and defect-rich Mg-Al oxide phases in situ on the core surface. These highly dispersed oxide phases more readily form high-melting-point magnesium aluminum silicates or calcium magnesium sulfates with Si / Al / Ca / K, increasing the overall ash phase melting point. Without the modified coking enhancer, although lightly calcined magnesium powder (MgO) and calcined kaolin (Al / Si) are still present, the lack of a highly active shell layer that allows for "heterogeneous in-situ growth on the particle surface" reduces the near-field synergy between Mg and Al, making it difficult to form an equal amount of high-melting-point phases, thus weakening the HT (heat transfer temperature) increase. Similarly, it cannot effectively block the connectivity of low-melting-point phases, leading to the formation and deposition of more viscous melt on the probe surface, relatively increasing adhesion and reducing the ash and slag suppression effect. Compared with the formulation in the example, the above indicators show a significant degradation, demonstrating the crucial role of the modified coking enhancer in improving high-temperature phase transformation, solidifying alkali metals, and synergistic denitrification.

[0071] If no magnesium source is added during the preparation of the modified coking enhancer, the near-field reaction opportunity between Al and K will be increased, which is beneficial for alkali solidification (K), but not for the construction of the MgO framework / slag-suppressing framework. Therefore, the final effect is better in "alkali solidification" and weaker in "slag-suppressing framework". If no aluminum source is added during the preparation of the modified coking enhancer, only the MgO coating can provide a certain "skeletalization" effect, but the lack of Al limits the formation of composite phases such as magnesium-aluminum-silicate that can synergistically raise the melting point. The K solidification rate is significantly reduced, and the alkali metal cannot be effectively solidified. The low melting phase residue may still lead to slag / agglomeration, and the impact on NO / NO2 removal is even smaller.

[0072] Modified coking enhancers, with their dual functions of "Mg framework and Al alkali metal fixation," achieve a multi-effect synergistic effect of slag suppression, ash suppression, alkali fixation, and desulfurization and denitrification assistance. They offer advantages such as low cost, high stability, and balanced performance, making them an upgraded solution compared to traditional single mineral or salt additives. Their synergistic effect with slag and ash suppressants significantly enhances slag and ash suppression, demonstrating a clear advantage even with small additions.

[0073] This invention can also be implemented in various other ways. Without departing from the spirit and essence of this invention, those skilled in the art can make various corresponding changes and modifications according to this invention, but these corresponding changes and modifications should all fall within the protection scope of the appended claims.

Claims

1. A desulfurization-enhancing coking, slag, and ash accumulation inhibitor, characterized in that, The raw materials for the inhibitor, by weight, include: The modified coking enhancer is composed of mineral powder as the core and Mg / Al composite metal nanosheets as the shell.

2. The coking, slag, and ash accumulation inhibitor according to claim 1, characterized in that, The Mg / Al composite metal nanosheets have a porous sheet structure, formed by stacking the sheets.

3. The coking, slag, and ash accumulation inhibitor according to claim 1, characterized in that, The molar ratio of Mg to Al is 3-8:

1.

4. The coking, slag, and ash accumulation inhibitor according to claim 1, characterized in that, The desulfurizing agent is selected from one or more combinations of oxalic acid, glutaric acid, succinic acid, or potassium permanganate; the denitrifying agent is selected from one or more combinations of sodium chlorite, urea, melamine monoamide, cyanuric acid monoamide, or cyanuric acid diamide.

5. The coking, slag, and ash accumulation inhibitor according to claim 1, characterized in that, The coal-saving agent is selected from one or more combinations of barium nitrate or borax; the alkali-fixing agent is selected from one or more combinations of calcined kaolin, high-alumina fly ash, ammonium dihydrogen phosphate, and monoammonium phosphate; the slag-suppressing and ash-suppressing agent is selected from one or more combinations of lightly calcined magnesia powder or brucite powder.

6. The coking, slag, and ash accumulation inhibitor according to claim 1, characterized in that, The preparation method of the modified coking enhancer includes the following steps: The nucleus powder is slurryed, Mg and Al sources are added, the pH is adjusted to alkaline, and the mixture is heated and aged to allow Mg and Al to form heterogeneous nuclei on the nucleus surface. After washing, drying and pre-activation, a modified coking enhancer is obtained.

7. The coking, slag, and ash accumulation inhibitor according to claim 6, characterized in that, The core powder is one or more of the following: dolomite powder, heavy calcium carbonate powder, calcite powder, apatite powder, or seaweed calcium powder; the Mg source is selected from one or more of the following: magnesite powder, lightly calcined magnesia powder, or brucite powder; the Al source is selected from one or more of the following: roasted kaolin, alunite, montmorillonite, chlorite, or orthoclase.

8. The coking, slag, and ash accumulation inhibitor according to claim 6, characterized in that, The alkalinity refers to a pH of 10-10.5; the heating aging refers to heating to 50-65℃ and aging for 60-120 minutes; the drying pre-activation refers to drying at 110℃ and lightly activating at 200-250℃ for 0.5-1 hour.

9. The method for preparing the coking, slag-forming, and ash-accumulating inhibitor according to any one of claims 1-8, characterized in that, include: Weigh the corresponding raw materials according to the above formula, add them to the powder mixer for uniform mixing, and obtain the coking, slag, and ash accumulation inhibitor.

10. The application of the coking, slagging, and ash-accumulating inhibitor according to any one of claims 1-8 or the coking, slagging, and ash-accumulating inhibitor prepared by the method of claim 9 in coal-fired industrial boilers / power plants, characterized in that, The application involves mixing coking, slagging, and ash-accumulating inhibitors with fuel and then adding them for combustion, with a dosage ratio of 0.4-1 wt% of the total fuel weight.

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