Efficient coal saving agent and preparation method thereof

Abstract

The invention relates to the technical field of fire coal additives, in particular to a high-efficiency coal saving agent and a preparation method thereof. The coal saving agent is prepared from the following raw materials in percentage by mass: 7-14% of an oxygen supply agent, 5-12% of a combustion improver, 5-13% of a catalyst, 0.1-1% of industrial waste residues, 1-3% of a desulfurization additive, 1-2% of a dispersing agent and the balance of deionized water, wherein the catalyst is a Ce-Mn / TiO2 catalyst, and the catalyst is a 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 characteristic of coal, improve the combustion efficiency and the combustion effect, and realize the efficient coal-saving effect under the condition of low mixing amount; meanwhile, desulfurization and denitrification can be achieved, emission of sulfide and nitric oxide is reduced, and environmental pollution can be prevented and controlled.

Description

Technical Field

[0001] The invention relates to the technical field of coal fuel additives, and in particular to a high-efficiency coal-saving agent and a preparation method thereof. Background Art

[0002] As the main energy source in my country, coal occupies an important position in the energy structure, and its supply accounts for about 70% of the total energy in my country. However, while the large-scale use of coal has promoted the rapid economic development, it has also brought negative impacts on the ecological environment and energy crisis. Therefore, the clean and efficient use of coal has been included in the national development plan, and coal-saving agent is one of the key technologies to achieve this goal.

[0003] The role of coal-saving agent is mainly reflected in three aspects: first, it improves the dispersion of coal powder and increases the contact area with air; second, it can release oxygen to assist combustion under heating; third, its catalytic components can reduce the ignition temperature of coal and increase the coal burnout rate. Traditional coal-saving agents mainly use a mixture of alkali metals, alkaline earth metals, and transition element metal salts as raw materials, and have the following disadvantages: large doping amount, even up to 5% of the amount of raw coal, low cost performance; excessive alkali metals, chloride ions, and sulfur elements will affect the quality of cement, and will cause serious corrosion to the combustion equipment and reduce the service life of the boiler; coal is prone to agglomeration during transportation, and it is difficult to burn fully, and it is impossible to ensure the process requirements of kiln coal burning resistance; the function is single, and it cannot reduce the emission of smoke and harmful gases in the exhaust gas. Therefore, it is urgent to develop a coal-saving agent with appropriate doping amount, good combustion 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 a preparation method thereof, which can effectively improve the combustion characteristics of coal, improve combustion efficiency and combustion effect, and achieve high-efficiency coal-saving effect under the condition of low dosage; at the same time, it can also desulfurize and denitrify, which is beneficial to prevent and control environmental pollution.

[0005] In the first aspect, the present invention provides a high-efficiency coal-saving agent, wherein the raw materials include the following components, in mass percentage: 7-14% oxygen supplier, 5-12% combustion aid, 5-13% catalyst, 0.1-1% industrial waste slag, 1-3% desulfurization additive and 1-2% dispersant, and the balance is 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, and the desulfurization additive is selected from at least one of calcium acetate, calcium oxide or calcium carbonate.

[0006] In the present invention, the cold-rolled iron oxide slag is the iron oxide slag produced in 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 in the present invention is a solid waste discharged from steelmaking. Preferably, the mass percentage of Al2O3 in the steel slag is 10%-15%, the mass percentage of CaO is 40%-50%, and the mass percentage of Fe2O3 is 5%-10%.

[0008] The nickel slag in the present invention is solid waste produced by pyrometallurgical smelting of nickel. Preferably, the nickel grade of the nickel slag is 0.5%-6%.

[0009] The coal-saving agent of the present invention adds a Ce-Mn / TiO2 catalyst, which mainly comprises TiO2, Mn3O4 and CeO2. During the combustion process, the active components Mn and Ce generate a large number of oxygen free radicals through the change of metal valence state, which promotes the conversion of sulfur dioxide into sulfur trioxide, promotes the progress of the intrinsic sulfur fixation reaction, and thus improves the sulfur fixation rate; at the same time, the process also promotes the diffusion of oxygen from the gas phase to the carbon surface, which is beneficial to the combustion and burning of fixed carbon.

[0010] Industrial waste slag is added to the coal-saving agent of the present invention, which plays a catalytic and combustion-supporting role on coal. On the one hand, the electron-donating ability of metal ions can increase the activity of carbon rings or carbon chains during coal combustion, which is beneficial to the combustion and burnout of fixed carbon. On the other hand, some metal oxides act as oxygen transmission 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, the substances present in the industrial waste slag can react with sulfur dioxide, and can catalyze the reduction reaction of NOx, and enhance the adsorption of NOx by coal powder, thereby reducing the release of sulfur dioxide and nitrogen oxides in the flue gas of coal powder combustion.

[0011] The coal-saving agent of the present invention utilizes the synergistic effect of the catalyst and the industrial waste slag. Under high temperature conditions, the metal oxides in the catalyst and the industrial waste slag components produce ion exchange in the molecular structure of the coal through oxygen transfer and electron migration, which can jointly promote the cracking reaction of the coal, increase the pore structure and surface active sites of the gasification product of the coal char, thereby increasing the specific surface area and pore volume of the coal char, and also convert the flue gas that should be discharged into flammable coal gas to participate in combustion, thereby improving the combustion reaction of the coal, reducing the initial ignition temperature of the coal powder, increasing the burnout rate of the coal powder, and improving the overall combustion effect of the coal powder.

[0012] The coal-saving agent of the present invention adds a specific desulfurization additive, which can prevent the coal from being bonded and filled with pores by molten materials at high temperature in the form of physical action, thereby increasing the specific surface area of ​​coal char; it can also catalyze dehydrogenation and dealkylation reactions, so that the specific surface area of ​​the coal warm gasification product char tends to increase. At the same time, the desulfurization additive and the catalyst in the present invention also have a synergistic effect in promoting the heterogeneous reduction of NO by coal char, and can solidify a large amount of sulfur oxides and nitrogen oxides generated in coal combustion to form sulfates and nitrates that are harmless to the environment and stable in nature, thereby reducing the content of sulfur dioxide and nitrogen oxides in coal-fired flue gas.

[0013] By adding a specific dispersant to the coal-saving agent of the present invention, the coal-saving agent components can be fully dispersed on the surface of the coal and penetrated into the interior of the coal, thereby improving the working efficiency of the coal-saving agent and further improving the calcination efficiency of the coal; and eliminating static electricity, ensuring the independence and dispersion effect of fine coal particles, reducing the agglomeration phenomenon during the coal transportation process, and making the coal burn more fully. The dispersant in the present invention is preferably sodium hexametaphosphate, and the phosphate group can form a stable complex with the Ce-Mn / TiO2 catalyst to enhance the negative charge on its surface, thereby improving the dispersion stability; at the same time, the phosphate ions can be adsorbed on the surface of the industrial waste residue, thereby aggravating the steric hindrance effect between the particles, improving the electrostatic repulsion between the particles, and playing a good dispersing role.

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

[0015] Dissolve cerium nitrate hexahydrate and manganese nitrate tetrahydrate in deionized water, add titanium dioxide nanoparticles, stir and mix, ultrasonicate for 1-2 hours, then dry at 80-120°C for 5-8 hours, and then calcine at 500-600°C for 2-5 hours. The solid product after calcination is ground and sieved to obtain the Ce-Mn / TiO2 catalyst.

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

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

[0018] Optionally, the combustion aid 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 dodecylbenzene sulfonate.

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

[0021] Step 1: Mix the oxygen supply agent, combustion aid, 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 slag to a particle size of less than 1 mm, then add acidic liquid, continue grinding for 15-60 minutes, filter, and obtain a finely ground product;

[0023] Step 3: Stir and mix the mixture, the ground material, the 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. The preferred acidic liquid can reduce the grinding energy consumption of industrial waste residues, and can also destroy the network structure of the glass in the industrial waste residues, causing defects, thereby increasing its activity.

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

[0026] In a third aspect, the present invention further provides the use of the above-mentioned coal-saving agent or the coal-saving agent prepared by the above-mentioned preparation method as a coal combustion-supporting catalyst in cement production or coal-fired power generation.

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

[0028] The coal-saving agent of the present invention can be used in various coal furnaces in the power, chemical and other industries, for example, it can be applied to pulverized coal furnaces or circulating fluidized bed boilers in power plants, cement plants, etc. The coal-saving agent has no particular restrictions on the type of coal and can be applied to the coal-burning process of various coals.

[0029] The coal-saving agent in the present invention can be contacted with coal in solid form or in the form of an aqueous solution without any particular limitation. However, since the amount of the coal-saving agent used is relatively small relative to the coal, and coal is generally in the form of large particles or blocks, it is preferred that the coal-saving agent is contacted with coal in the form of an aqueous solution.

[0030] In the present invention, when the coal-saving agent is in the form of an aqueous solution and contacts the coal, the coal-saving agent can be fully dissolved in water before use, and then contacted with the coal by spraying. By preparing the coal-saving agent as an aqueous solution, not only can the uniform contact between the coal-fired catalyst and the coal be ensured, but the aqueous solution can also absorb suspended matter such as dust in the air during the spraying process, thereby purifying the production environment.

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

[0032] The coal-saving agent of the present invention is a composite system constructed by an oxygen supply agent, a combustion-supporting agent, a catalyst, industrial waste residue, a desulfurization additive and a dispersant, which effectively improves the combustion characteristics of coal, improves the combustion efficiency and combustion effect, and achieves a high-efficiency 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 is beneficial to the prevention and control of environmental pollution. The coal-saving agent of the present invention is mainly suitable for various lignite, coke, bituminous coal and anthracite, and can be used in various coal-fired equipment such as chain furnaces, boiling furnaces, forging furnaces, fluidized bed furnaces, pulverized coal furnaces, cement rotary kilns, etc., and the preparation method is simple, the cost is low, it is non-toxic and harmless, it is equipment-friendly, and has broad application prospects. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with embodiment. Unless otherwise defined, all professional terms used hereinafter are the same as those skilled in the art generally understand. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Unless otherwise specified, the various reagents and raw materials used in the present invention are all commodities that can be purchased from the market or products that can be prepared by known methods.

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

[0035] In order to better illustrate the present invention, further examples are given below.

[0036] Example 1

[0037] The present embodiment provides a coal saving agent, wherein the raw materials include the following components, in percentage by mass: 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, and the balance is deionized water.

[0038] The catalyst is prepared by the following scheme:

[0039] According to the element mass ratio of each raw material being 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, and ultrasonicated for 1.5 hours, then dried at 100°C for 6 hours, and then calcined at 550°C for 3 hours. The solid product after calcination was ground and sieved to obtain a catalyst.

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

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

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

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

[0044] Example 2

[0045] The present embodiment provides a coal saving agent, wherein the raw materials include the following components, in percentage by mass: 7% sodium chlorate, 5% potassium hydroxide, 5% Ce-Mn / TiO2 catalyst, 0.1% cold rolled iron oxide slag, 1% calcium carbonate and 1% sodium dodecylbenzene sulfonate, and the balance is deionized water.

[0046] The catalyst is prepared by the following scheme:

[0047] According to the element mass ratio of each raw material being 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, and ultrasonicated for 1 hour, then dried at 80°C for 5 hours, and then calcined at 500°C for 2 hours. The solid product after calcination was ground and sieved to obtain a catalyst.

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

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

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

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

[0052] Example 3

[0053] The present embodiment provides a coal-saving agent. The raw materials include the following components, measured by mass percentage: 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, and the balance is deionized water.

[0054] The catalyst is prepared by the following scheme:

[0055] According to the element mass ratio of each raw material being 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, and ultrasonicated for 2 hours, then dried at 120°C for 8 hours, and then calcined at 600°C for 5 hours. The solid product after calcination was ground and sieved to obtain a catalyst.

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

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

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

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

[0060] Comparative Example 1

[0061] This comparative example provides a coal-saving agent, and its preparation process is the same as that of Example 1, except that an equal amount of oxygen supply agent is used instead of industrial waste slag, that is, the raw materials of the 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, and the balance is deionized water.

[0062] Comparative Example 2

[0063] This comparative example provides a coal-saving agent, whose preparation process is the same as that of Example 1, except that equal amounts of ferric oxide and nickel oxide are used instead of industrial waste slag, that is, the raw materials of the 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, and the balance is deionized water.

[0064] Effect test:

[0065] Take equal amounts of different types of coal, add the coal-saving agents of the embodiment and the comparative example at a ratio of 0.1%, carry out combustion experiments in a circulating fluidized bed, calculate the coal-saving rate, and 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 of the embodiment and the comparative example were added into cement kiln fuel coal with a moisture content of 15% at a ratio of 0.1%, and combustion experiments were carried out on the raw coal samples and the samples with the coal-saving agents using a horizontal tube furnace test bench, a high-temperature cracker and a gas chromatography-mass spectrometry analysis system to test the combustion conditions and the production of pollutants.

[0069] Table 2 The highest peak values ​​and burnout rates of nitrogen oxides and sulfur dioxide during combustion

[0070]

[0071] In summary, the coal-saving agent prepared by the present invention can be applied to a variety of coals such as bituminous coal, coke, and lignite, and has good coal-saving, desulfurization, and denitrification effects at a low dosage.

[0072] The embodiments described above only express several preferred embodiments of the present invention, and the descriptions thereof are relatively specific and detailed, but are not intended to limit the present invention. It should be noted that for those skilled in the art, the present invention may also have various changes and modifications, and any modifications, equivalent substitutions, improvements, etc. made within the concept and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A coal-saving agent, characterized in that: The raw materials include the following components by mass percentage: 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, and the balance is deionized water; Wherein, the catalyst is 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; and the desulfurization additive is selected from at least one of calcium acetate, calcium oxide or calcium carbonate.

2. The coal-saving agent according to claim 1, characterized in that: The preparation method of the Ce-Mn / TiO2 catalyst comprises the following steps: Dissolve cerium nitrate hexahydrate and manganese nitrate tetrahydrate in deionized water, add titanium dioxide nanoparticles, stir and mix, ultrasonicate for 1-2 hours, then dry at 80-120°C for 5-8 hours, and then calcine at 500-600°C for 2-5 hours. The solid product after calcination is ground and sieved to obtain the Ce-Mn / TiO2 catalyst.

3. The coal-saving agent according to claim 1 or 2, characterized in that: In the catalyst, the element mass ratio of each raw material is Ce:Mn:Ti=0.05-0.1:0.2-0.4:

1.

4. The coal-saving agent according to claim 1, characterized in that: The oxygen supply agent is selected from at least one of potassium chlorate, sodium chlorate, calcium chlorate, potassium permanganate or sodium permanganate.

5. The coal-saving agent according to claim 1, characterized in that: The combustion improver is selected from at least one of sodium hydroxide and potassium hydroxide.

6. The coal-saving agent according to claim 1, characterized in that: The dispersant is selected from at least one of sodium hexametaphosphate, ammonium citrate, polyacrylamide or sodium dodecylbenzene sulfonate.

7. A method for preparing the coal-saving agent according to any one of claims 1 to 7, characterized in that: The preparation method comprises the following steps: Step 1: Mix the oxygen supply agent, combustion aid, catalyst and desulfurization additive, and grind them to a fineness of 200-500 mesh to obtain a mixture; Step 2: Grind the industrial waste slag to a particle size of less than 1 mm, then add acidic liquid, continue grinding for 15-60 minutes, filter, and obtain a finely ground product; Step 3: Stir and mix the mixture, the ground material, the dispersant and deionized water to obtain the coal saving agent.

8. The preparation method according to claim 7, characterized in that: The acidic liquid is selected from at least one of formic acid, oxalic acid, glacial acetic acid or phosphoric acid.

9. Use of the coal-saving agent according to any one of claims 1 to 6 or the coal-saving agent prepared by the preparation method according to any one of claims 7 to 8 as a coal combustion-supporting catalyst in cement production or coal-fired power generation.

10. The use according to claim 9, characterized in that The usage amount of the coal-saving agent is 0.05%-0.3% of the coal mass.

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