A high-efficiency coal-saving agent and its preparation method

Abstract

The present invention relates to the technical field of coal-fired additives, and in particular to a high-efficiency coal-saving agent and a preparation method thereof. The coal-saving agent comprises the following raw materials in percentage by mass: 7-14% oxygen supply agent, 5-12% combustion aid, 5-13% catalyst, 0.1-1% industrial waste slag, 1-3% desulfurization additive and 1-2% dispersant, with the balance being deionized water; wherein the catalyst is a Ce-Mn / TiO2 catalyst; the industrial waste slag is selected from at least one of cold-rolled iron oxide slag, nickel slag or steel slag; the desulfurization additive is selected from at least one of calcium acetate, calcium oxide or calcium carbonate. The coal-saving agent can effectively improve the combustion characteristics of coal, improve combustion efficiency and combustion effect, and achieve efficient coal-saving effect under the condition of low dosage; at the same time, it can also desulfurize and denitrify, reduce the emission of sulfides and nitrogen oxides, and help prevent and control environmental pollution.

Description

Technical Field

[0001] This invention relates to the field of coal additives, and in particular to a high-efficiency coal-saving agent and its preparation method. Background Technology

[0002] Coal, as my country's primary energy source, occupies a crucial position in the energy structure, accounting for approximately 70% of the country's total energy supply. However, while the large-scale utilization of coal has driven rapid economic development, it has also brought negative impacts on the ecological environment and energy crisis. Therefore, the clean and efficient utilization of coal has been incorporated into national development plans, and coal-saving agents are one of the key technologies for achieving this goal.

[0003] The role of coal-saving agents is mainly reflected in three aspects: First, improving the dispersibility of pulverized coal and increasing the contact area with air; second, releasing oxygen to aid combustion when heated; and third, its catalytic components can lower the ignition temperature of coal and improve the coal combustion rate. Traditional coal-saving agents mainly use mixtures of alkali metals, alkaline earth metals, and transition metal salts as raw materials, which have many drawbacks: high adulteration levels, sometimes reaching 5% of the raw coal content, resulting in low cost-effectiveness; excessive levels of alkali metals, chloride ions, and sulfur can affect cement quality and cause severe corrosion to combustion equipment, reducing boiler lifespan; coal is prone to caking during transportation, making complete combustion difficult and failing to meet the process requirements for long-burning coal in kilns; and its function is limited, failing to reduce emissions of smoke and harmful gases in the exhaust gas. Therefore, there is an urgent need to develop a coal-saving agent with appropriate dosage, good combustion-aiding effect, and low content of harmful components. Summary of the Invention

[0004] In view of this, the present invention provides a high-efficiency coal-saving agent and its preparation method, which can effectively improve the combustion characteristics of coal, increase combustion efficiency and combustion effect, and achieve high-efficiency coal saving under the condition of low dosage; at the same time, it can also desulfurize and denitrify, which is beneficial to the prevention and control of environmental pollution.

[0005] In a first aspect, the present invention provides a high-efficiency coal-saving agent, wherein the raw materials, by mass percentage, include the following components: 7-14% oxygen supply agent, 5-12% combustion aid, 5-13% catalyst, 0.1-1% industrial waste residue, 1-3% desulfurization additive, and 1-2% dispersant, with the balance being deionized water; wherein the catalyst is a Ce-Mn / TiO2 catalyst, the industrial waste residue is selected from at least one of cold-rolled iron oxide slag, nickel slag, or steel slag, and the desulfurization additive is selected from at least one of calcium acetate, calcium oxide, or calcium carbonate.

[0006] In this invention, the cold-rolled iron oxide slag is iron oxide slag produced during the steel rolling process. Preferably, the mass percentage content of Fe2O3 in the cold-rolled iron oxide slag is 85%-96%.

[0007] The steel slag mentioned in this invention is a solid waste discharged from steelmaking. Preferably, the steel slag contains 10%-15% Al2O3 by mass, 40%-50% CaO by mass, and 5%-10% Fe2O3 by mass.

[0008] The nickel slag described in this invention is a solid waste product generated from pyrometallurgical refining of metallic nickel. Preferably, the nickel grade of the nickel slag is 0.5%-6%.

[0009] The coal-saving agent of this invention incorporates a Ce-Mn / TiO2 catalyst, which mainly comprises TiO2, Mn3O4, and CeO2. During combustion, the active components Mn and Ce generate a large number of oxygen free radicals through changes in their metal valence states, promoting the conversion of sulfur dioxide into sulfur trioxide and facilitating the intrinsic sulfur fixation reaction, thereby increasing the sulfur fixation rate. Simultaneously, this process also promotes the diffusion of oxygen from the gas phase to the carbon surface, which is beneficial for the combustion and burnout of fixed carbon.

[0010] The coal-saving agent of this invention incorporates industrial waste residue, which acts as a catalytic combustion aid for coal. On the one hand, the electron-donating ability of metal ions increases the activity of carbon rings or carbon chains during coal combustion, which is beneficial for the combustion and burnout of fixed carbon. On the other hand, some metal oxides act as oxygen transport media during coal ignition, promoting the diffusion of oxygen from the gas phase to the surface, which helps the fixed carbon to burn fully and quickly. At the same time, substances present in industrial waste residue can react with sulfur dioxide and catalyze the reduction reaction of NOx, and enhance the adsorption of NOx by pulverized coal, thereby reducing the release of sulfur dioxide and nitrogen oxides in the flue gas from pulverized coal combustion.

[0011] The coal-saving agent of this invention utilizes the synergistic effect of a catalyst and industrial waste residue. Under high-temperature conditions, the metal oxides in the catalyst and industrial waste residue components undergo ion exchange in the molecular structure of coal through oxygen transfer and electron migration. This jointly promotes the coal cracking reaction, increases the pore structure and surface active sites of the coal char gasification products, thereby increasing the specific surface area and pore volume of the coal char. Furthermore, it transforms the flue gas that should be emitted into flammable coal gas to participate in combustion, thereby improving the coal combustion reaction, reducing the initial ignition temperature of pulverized coal, increasing the burnout rate of pulverized coal, and improving the overall combustion effect of pulverized coal.

[0012] The coal-saving agent of this invention, by adding specific desulfurization additives, can physically prevent the molten material in coal from sticking and filling the pores at high temperatures, thereby increasing the specific surface area of ​​the coal char. It can also catalyze dehydrogenation and dealkylation reactions, resulting in an increase in the specific surface area of ​​the coal temperature and the gasification product char. Simultaneously, the desulfurization additives and catalysts in this invention have a synergistic effect in promoting the heterogeneous reduction of NO in coal char, solidifying the large amounts of sulfur oxides and nitrogen oxides produced during coal combustion into environmentally harmless and stable sulfates and nitrates, thereby reducing the content of sulfur dioxide and nitrogen oxides in coal combustion flue gas.

[0013] The coal-saving agent of this invention, by adding a specific dispersant, allows the coal-saving agent components to be fully dispersed on the coal surface and penetrate into the coal interior, improving the working efficiency of the coal-saving agent and thus improving the calcination efficiency of the coal. Furthermore, it eliminates static electricity, ensuring the independence and dispersion of fine coal particles, reducing agglomeration during coal transportation, and promoting more complete combustion. The preferred dispersant in this invention is sodium hexametaphosphate. The phosphate groups can form stable complexes with the Ce-Mn / TiO2 catalyst, enhancing the negative charge on its surface and thus improving dispersion stability. Simultaneously, phosphate ions can be adsorbed onto the surface of industrial waste residue, intensifying the steric hindrance effect between particles and increasing electrostatic repulsion, resulting in excellent dispersion.

[0014] Optionally, the preparation method of the Ce-Mn / TiO2 catalyst includes the following steps:

[0015] Cerium nitrate hexahydrate and manganese nitrate tetrahydrate were dissolved in deionized water, and titanium dioxide nanoparticles were added and stirred. The mixture was ultrasonicated for 1-2 hours, then dried at 80-120℃ for 5-8 hours, and then calcined at 500-600℃ for 2-5 hours. The calcined solid product was ground and sieved to obtain the Ce-Mn / TiO2 catalyst.

[0016] Optionally, in the catalyst, the elemental mass ratio of each raw material is Ce:Mn:Ti = 0.05-0.1:0.2-0.4:1.

[0017] Optionally, the oxygen-supplying agent is selected from at least one of potassium chlorate, sodium chlorate, calcium chlorate, potassium permanganate, or sodium permanganate.

[0018] Optionally, the combustion improver is selected from at least one of sodium hydroxide or potassium hydroxide.

[0019] Optionally, the dispersant is selected from at least one of sodium hexametaphosphate, ammonium citrate, polyacrylamide, or sodium dodecylbenzenesulfonate.

[0020] Secondly, the present invention also provides a method for preparing the above-mentioned coal-saving agent, the method comprising the following steps:

[0021] Step 1: Mix the oxygen supply agent, combustion improver, catalyst and desulfurization additive, and grind them to a fineness of 200-500 mesh to obtain a mixture;

[0022] Step 2: Grind the industrial waste residue to a particle size of less than 1 mm, then add acidic liquid and continue grinding for 15-60 minutes. Filter to obtain the finely ground material.

[0023] Step 3: Mix the mixture, finely ground material, dispersant, and deionized water to obtain the coal-saving agent.

[0024] Optionally, the acidic liquid is selected from at least one of formic acid, oxalic acid, glacial acetic acid, or phosphoric acid. Preferred acidic liquids can reduce the energy consumption of grinding industrial waste residues and can also disrupt the network structure of the vitreous body in the industrial waste residues, creating defects and thus improving their activity.

[0025] Optionally, the amount of acidic liquid added is 8%-12% of the mass of industrial waste residue.

[0026] Thirdly, the present invention also provides the application of the above-mentioned coal-saving agent or the coal-saving agent prepared by the above-mentioned preparation method as a coal combustion catalyst in the cement production or coal power industry.

[0027] Optionally, the amount of the coal-saving agent used is 0.05%-0.3% of the coal mass.

[0028] The coal-saving agent described in this invention can be used in various coal-fired boilers in industries such as power and chemical manufacturing. For example, it can be applied to pulverized coal boilers or circulating fluidized bed boilers in power plants and cement plants. The coal-saving agent is not particularly limited by the type of coal and can be applied to the combustion process of various types of coal.

[0029] The coal-saving agent described in this invention can contact coal in solid form or aqueous solution form, without particular limitation. However, since the amount of coal-saving agent relative to the amount of coal is relatively small, and the coal is generally in the form of large particles or lumps, it is preferable that the coal-saving agent contact the coal in aqueous solution form.

[0030] In this invention, when the coal-saving agent comes into contact with coal in the form of an aqueous solution, the coal-saving agent can be fully dissolved in water before use, and then sprayed onto the coal. By preparing the coal-saving agent as an aqueous solution, not only can uniform contact between the coal-fired catalyst and the coal be ensured, but the aqueous solution can also adsorb suspended matter such as dust in the air during the spraying process, thus purifying the production environment.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] This invention's coal-saving agent, a composite system comprised of oxygen-providing agent, combustion aid, catalyst, industrial waste residue, desulfurization additive, and dispersant, effectively improves the combustion characteristics of coal, enhancing combustion efficiency and effect, achieving high-efficiency coal saving even with low admixture dosage. Simultaneously, it desulfurizes and denitrifies, reducing emissions of sulfides and nitrogen oxides, thus contributing to environmental pollution control. This coal-saving agent is primarily applicable to various types of lignite, coke, bituminous coal, and anthracite, and can be used in various coal-fired equipment such as chain grate furnaces, fluidized bed furnaces, forging furnaces, fluidized bed furnaces, pulverized coal furnaces, and cement rotary kilns. Furthermore, its preparation method is simple, low-cost, non-toxic, harmless, and equipment-friendly, possessing broad application prospects. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the scope of protection of this invention. Unless otherwise specified, all reagents and raw materials used in this invention are commercially available products or products that can be prepared by known methods.

[0034] In this invention, the coal saving rate refers to the difference in the amount of fuel used to produce the same heat under the same combustion environment, that is, the coal saving rate = (original coal consumption - coal consumption after using the coal-fired catalyst) / original coal consumption.

[0035] To better illustrate the present invention, further examples are provided below.

[0036] Example 1

[0037] This embodiment provides a coal-saving agent, which, by mass percentage, comprises the following raw materials: 6% potassium chlorate, 4% calcium chlorate, 8% sodium hydroxide, 9% Ce-Mn / TiO2 catalyst, 0.4% cold-rolled iron oxide slag, 0.2% nickel slag, 23% calcium acetate, and 1.5% sodium hexametaphosphate, with the balance being deionized water.

[0038] The catalyst was prepared using the following method:

[0039] According to the elemental mass ratio of each raw material Ce:Mn:Ti = 0.08:0.3:1, cerium nitrate hexahydrate and manganese nitrate tetrahydrate were dissolved in deionized water, titanium dioxide nanoparticles were added and stirred, ultrasonicated for 1.5 h, then dried at 100℃ for 6 h, and then calcined at 550℃ for 3 h. The solid product after calcination was ground and sieved to obtain the catalyst.

[0040] This embodiment provides a method for preparing the above-mentioned coal-saving agent:

[0041] Step 1: Mix the oxygen supply agent, combustion improver, catalyst and desulfurization additive, and grind them to a fineness of 200-500 mesh to obtain a mixture;

[0042] Step 2: Grind the industrial waste residue to a particle size of less than 1 mm, then add formic acid (8% of the mass of the industrial waste residue), continue grinding for 30 minutes, filter, and obtain the finely ground material;

[0043] Step 3: Mix the mixture, finely ground material, dispersant, and deionized water to obtain the coal-saving agent.

[0044] Example 2

[0045] This embodiment provides a coal-saving agent, which, by mass percentage, comprises the following raw materials: 7% sodium chlorate, 5% potassium hydroxide, 5% Ce-Mn / TiO2 catalyst, 0.1% cold-rolled iron oxide slag, 1% calcium carbonate, and 1% sodium dodecylbenzenesulfonate, with the balance being deionized water.

[0046] The catalyst was prepared using the following method:

[0047] According to the elemental mass ratio of each raw material Ce:Mn:Ti = 0.05:0.2:1, cerium nitrate hexahydrate and manganese nitrate tetrahydrate were dissolved in deionized water, titanium dioxide nanoparticles were added and stirred, ultrasonicated for 1 hour, then dried at 80℃ for 5 hours, and then calcined at 500℃ for 2 hours. The calcined solid product was ground and sieved to obtain the catalyst.

[0048] This embodiment provides a method for preparing the above-mentioned coal-saving agent:

[0049] Step 1: Mix the oxygen supply agent, combustion improver, catalyst and desulfurization additive, and grind them to a fineness of 200-500 mesh to obtain a mixture;

[0050] Step 2: Grind the industrial waste residue to a particle size of less than 1 mm, then add formic acid and oxalic acid (8% of the mass of the industrial waste residue), continue grinding for 15 minutes, filter, and obtain the finely ground material;

[0051] Step 3: Mix the mixture, finely ground material, dispersant, and deionized water to obtain the coal-saving agent.

[0052] Example 3

[0053] This embodiment provides a coal-saving agent, which, by mass percentage, comprises the following raw materials: 3% potassium permanganate, 7% sodium chlorate, 4% calcium chlorate, 6% sodium hydroxide, 6% potassium hydroxide, 13% Ce-Mn / TiO2 catalyst, 0.4% cold-rolled iron oxide slag, 0.3% nickel slag, 0.3% steel slag, 1% calcium acetate, 1% calcium oxide, 1% calcium carbonate, 1% sodium hexametaphosphate, and 1% ammonium citrate, with the balance being deionized water.

[0054] The catalyst was prepared using the following method:

[0055] According to the elemental mass ratio of each raw material Ce:Mn:Ti = 0.1:0.4:1, cerium nitrate hexahydrate and manganese nitrate tetrahydrate were dissolved in deionized water, titanium dioxide nanoparticles were added and stirred, ultrasonicated for 2 hours, then dried at 120℃ for 8 hours, and then calcined at 600℃ for 5 hours. The calcined solid product was ground and sieved to obtain the catalyst.

[0056] This embodiment provides a method for preparing the above-mentioned coal-saving agent:

[0057] Step 1: Mix the oxygen supply agent, combustion improver, catalyst and desulfurization additive, and grind them to a fineness of 200-500 mesh to obtain a mixture;

[0058] Step 2: Grind the industrial waste residue to a particle size of less than 1 mm, then add phosphoric acid (8% of the mass of the industrial waste residue), continue grinding for 60 minutes, filter, and obtain the finely ground material;

[0059] Step 3: Mix the mixture, finely ground material, dispersant, and deionized water to obtain the coal-saving agent.

[0060] Comparative Example 1

[0061] This comparative example provides a coal-saving agent, the preparation process of which is the same as in Example 1, except that an equal amount of oxygen-supplying agent is used to replace industrial waste residue. That is, the raw materials of this coal-saving agent include the following components: 6.4% potassium chlorate, 4.2% calcium chlorate, 8% sodium hydroxide, 9% Ce-Mn / TiO2 catalyst, 23% calcium acetate, and 1.5% sodium hexametaphosphate, with the balance being deionized water.

[0062] Comparative Example 2

[0063] This comparative example provides a coal-saving agent, the preparation process of which is the same as in Example 1, except that equal amounts of ferric oxide and nickel oxide are used instead of industrial waste residue. That is, the raw materials of this coal-saving agent include the following components: 6% potassium chlorate, 4% calcium chlorate, 8% sodium hydroxide, 9% Ce-Mn / TiO2 catalyst, 0.4% ferric oxide, 0.2% nickel oxide, 23% calcium acetate and 1.5% sodium hexametaphosphate, with the balance being deionized water.

[0064] Effect test:

[0065] Equal amounts of different types of coal were taken, and the coal-saving agents of the examples and comparative examples were added at a ratio of 0.1% respectively. Combustion experiments were carried out in a circulating fluidized bed, and the coal-saving rate was calculated. The results are shown in Table 1.

[0066] Table 1 Coal Saving Rate

[0067] bituminous coal coke lignite Example 1 26.7％ 19.8％ 34.5％ Example 2 25.4％ 18.4％ 32.4％ Example 3 26.1％ 17.9％ 33.1％ Comparative Example 1 17.1％ 13.9％ 18.8％ Comparative Example 2 15.3％ 11.7％ 16.5％

[0068] The coal-saving agents from the examples and comparative examples were added to cement kiln coal with a moisture content of 15% at a ratio of 0.1%. Combustion experiments were conducted on the raw coal samples and the samples with added coal-saving agents using a horizontal tubular furnace experimental rig and a high-temperature pyrolyzer and gas chromatography-mass spectrometry system, respectively, to test the combustion status and the production of pollutants.

[0069] Table 2. Peak values ​​and burnout rates of nitrogen oxides and sulfur dioxide during combustion.

[0070]

[0071] In summary, the coal-saving agent prepared by this invention is applicable to various types of coal, such as bituminous coal, coke, and lignite, and has good coal-saving, desulfurization, and denitrification effects while having a low dosage.

[0072] The embodiments described above are merely preferred embodiments of the present invention, and while the descriptions are specific and detailed, they are not intended to limit the present invention. It should be noted that various changes and modifications can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the concept and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A coal-saving agent, characterized in that, By mass percentage, the raw materials include the following components: 7-14% oxygen supply agent, 5-12% combustion improver, 5-13% catalyst, 0.1-1% industrial waste residue, 1-3% desulfurization additive, and 1-2% dispersant, with the balance being deionized water; The catalyst is a Ce-Mn / TiO2 catalyst, wherein the elemental mass ratio of each raw material in the catalyst is Ce:Mn:Ti = 0.05-0.1:0.2-0.4:1; the industrial waste residue is selected from at least one of cold-rolled iron oxide slag, nickel slag, or steel slag; the desulfurization additive is selected from at least one of calcium acetate, calcium oxide, or calcium carbonate; the oxygen supply agent is selected from at least one of potassium chlorate, sodium chlorate, calcium chlorate, potassium permanganate, or sodium permanganate; the combustion aid is selected from at least one of sodium hydroxide or potassium hydroxide; and the dispersant is selected from at least one of sodium hexametaphosphate, ammonium citrate, polyacrylamide, or sodium dodecylbenzenesulfonate.

2. The coal-saving agent as described in claim 1, characterized in that, The preparation method of the Ce-Mn / TiO2 catalyst includes the following steps: Cerium nitrate hexahydrate and manganese nitrate tetrahydrate were dissolved in deionized water, and titanium dioxide nanoparticles were added and stirred. The mixture was ultrasonicated for 1-2 hours, then dried at 80-120℃ for 5-8 hours, and then calcined at 500-600℃ for 2-5 hours. The calcined solid product was ground and sieved to obtain the Ce-Mn / TiO2 catalyst.

3. A method for preparing a coal-saving agent according to any one of claims 1-2, characterized in that, The preparation method includes the following steps: Step 1: Mix the oxygen supply agent, combustion improver, catalyst and desulfurization additive, and grind them to a fineness of 200-500 mesh to obtain a mixture; Step 2: Grind the industrial waste residue to a particle size of less than 1 mm, then add acidic liquid and continue grinding for 15-60 minutes. Filter to obtain the finely ground material. Step 3: Mix the mixture, finely ground material, dispersant, and deionized water to obtain the coal-saving agent.

4. The preparation method according to claim 3, characterized in that, The acidic liquid is selected from at least one of formic acid, oxalic acid, glacial acetic acid, or phosphoric acid.

5. The coal-saving agent according to any one of claims 1-2, or the coal-saving agent prepared by any one of claims 3-4, is used as a coal combustion catalyst in cement production or coal-fired power generation.

6. The application as described in claim 5, characterized in that, The amount of the coal-saving agent used is 0.05%-0.3% of the coal mass.

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