Combustion improver and preparation method thereof

Abstract

The invention provides a combustion improver and a preparation method thereof, and the combustion improver comprises the following raw materials by mass: 3-7 parts of nano cerium oxide, 10-20 parts of potassium nitrate, 8-15 parts of iron oxide, 40-60 parts of modified diatomite, 10-20 parts of sodium carboxymethyl cellulose, 1-5 parts of zinc borate, and 1-3 parts of sodium dodecyl benzene sulfonate. The nano cerium oxide is used as a catalyst, so that the combustion reaction can be accelerated; potassium nitrate and ferric oxide provide necessary oxygen elements to promote sufficient combustion of the fuel; the modified diatomite has high adsorbability and stability; sodium carboxymethyl cellulose is used as a binder, so that the stability and the dispersity of the combustion improver are enhanced; zinc borate and sodium dodecyl benzene sulfonate respectively play the roles of flame retardance and a surfactant, and the raw materials are combined, so that the combustion efficiency is improved, and the emission of harmful substances is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of fuel additives, and in particular to a combustion improver and a preparation method thereof. Background Art

[0002] The main pollutants produced during coal combustion include carbon dioxide, carbon monoxide, sulfur dioxide, nitrogen monoxide, and dust. These pollutants contribute to air pollution and are a major factor in the formation of smog. Therefore, improving coal combustion efficiency, reducing pollutant emissions, and achieving clean and efficient coal combustion not only have high economic benefits but also significant social significance. To achieve this goal, the use of coal combustion promoters is one of the more effective measures. Adding combustion promoters to coal can significantly improve its combustion characteristics. Specifically, it can increase the precipitation rate of coal volatiles, lower the coal ignition point, accelerate the combustion rate of coke, shorten the combustion time, and thus improve the coal's combustion efficiency. By adding a small amount of promoter to coal, it can promote complete combustion while reducing dust and pollutant emissions.

[0003] Traditional combustion aids, such as potassium permanganate and sodium nitrate, suffer from short durations of action (<48 hours) and are prone to decomposition and ineffectiveness at high temperatures. Therefore, prolonging the release cycle of active components in combustion aids and improving catalytic efficiency at low temperatures (<500°C) have become pressing challenges. Summary of the Invention

[0004] The present application is made in view of the above problems, and its purpose is to provide a combustion improver and a preparation method thereof, so as to achieve efficient combustion of fuel through rare earth-transition metal synergistic catalysis and physical slow-release technology.

[0005] Specifically, the first aspect of the present application provides a combustion aid, which includes the following raw materials in parts by mass: 3-7 parts of nano-cerium oxide, 10-20 parts of potassium nitrate, 8-15 parts of iron oxide, 40-60 parts of modified diatomaceous earth, 10-20 parts of sodium carboxymethyl cellulose, 1-5 parts of zinc borate, and 1-3 parts of sodium dodecylbenzene sulfonate.

[0006] Furthermore, the particle size of the nano-cerium oxide is 20-50 nm.

[0007] Furthermore, the pore size of the modified diatomaceous earth is 10-50 nm.

[0008] The second aspect of the present application provides a method for preparing the combustion improver, comprising the following steps:

[0009] S1: mixing potassium nitrate and nano-cerium oxide and spray drying to obtain a pre-composite active powder;

[0010] S2: mixing modified diatomaceous earth, sodium carboxymethyl cellulose, pre-compounded active powder, iron oxide, zinc borate, and sodium dodecylbenzenesulfonate to obtain a mixed material;

[0011] S3: granulating and coating the mixed material.

[0012] Furthermore, in step S1, potassium nitrate is dissolved in water to obtain a potassium nitrate solution with a mass concentration of 28-30%, and then nano-cerium oxide powder is added and ultrasonically dispersed for 30-40 minutes to obtain a mixed solution; and / or

[0013] The frequency of the ultrasonic dispersion is 40-50 kHz.

[0014] Furthermore, the inlet temperature of the spray drying in step S1 is 160-190°C; and / or

[0015] The outlet temperature of the spray drying is 70-90°C.

[0016] Furthermore, the modification method of the modified diatomaceous earth in step S2 is: calcining the diatomaceous earth at 600-650° C. and then ball milling; and / or

[0017] The calcination time is 1-3h; and / or

[0018] Ball mill the diatomaceous earth to a particle size of 200-250 mesh.

[0019] Furthermore, the mixing speed in step S2 is 700-850 rpm; and / or

[0020] The mixing temperature is 50-60°C; and / or

[0021] The mixing time is 20-30 minutes.

[0022] Furthermore, the granulation in step S3 is to spray a binder into the mixed material and simultaneously enter the fluidized bed dryer to form particles; and / or

[0023] The spraying rate of the adhesive is 0.4-0.6 L / min; and / or

[0024] The inlet air temperature of the fluidized bed granulation is 75-85°C; and / or

[0025] The wind speed of the fluidized bed granulation is 1.1-1.5 m / s.

[0026] Furthermore, the coating in step S3 is to spray a fumed silica suspension into the particles to form a silica coating layer with a thickness of ≤50 μm on the surface of the particles, followed by drying.

[0027] The present invention has the following beneficial effects:

[0028] The synergistic effect of the components in the combustion-supporting agent formula of the present invention not only improves the combustion efficiency of coal, but also significantly prolongs the release cycle of the active components of the combustion-supporting agent. Among them, the composite of nano-cerium oxide and potassium nitrate, the pre-composite active powder formed by spray drying, has excellent catalytic performance, can effectively reduce the ignition point of coal, and accelerate the combustion speed; modified diatomaceous earth is used as a carrier, and its unique pore structure is conducive to the uniform dispersion and slow release of active components, thereby improving the stability of the combustion-supporting agent; in addition, nano-cerium oxide serves as an electron acceptor and iron oxide serves as an electron donor. During the combustion process, the electron transfer between the two promotes the progress of the combustion chain reaction, thereby improving the combustion efficiency. Potassium nitrate is embedded in the pores of the modified diatomaceous earth to achieve gradient release; at the same time, the rare earth properties of nano-cerium oxide are combined with the transition metal properties of iron oxide, and through synergistic catalysis, the combustion efficiency of coal is effectively improved and the emission of harmful gases is reduced; the addition of sodium carboxymethyl cellulose enhances the adhesiveness and formability of the combustion-supporting agent, making the granulation process smoother; zinc borate and sodium dodecylbenzene sulfonate respectively play the role of flame retardancy and dispersion, further improving the comprehensive performance of the combustion-supporting agent.

[0029] In addition, the preparation method of the combustion improver of the present invention has simple process, convenient operation, easy to realize industrial production, and has high practical value. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solutions and advantages of this application more clearly understood, the present application is described and illustrated below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are merely used to explain this application and are not intended to limit this application. Based on the embodiments provided in this application, all other embodiments obtained by those of ordinary skill in the art without making any creative work are within the scope of protection of this application.

[0031] Obviously, the following descriptions are merely some examples or embodiments of the present application. Those skilled in the art can apply the present application to other similar scenarios without inventive effort. Furthermore, it is also understood that, although the effort involved in such a development process may be complex and lengthy, for those skilled in the art related to the content disclosed in the present application, changes in design, manufacturing, or production based on the technical content disclosed in the present application are merely conventional technical means and should not be construed as an insufficiency of the content disclosed in the present application.

[0032] Unless otherwise specified, the terms "include" and "comprising" used in this application may be open-ended or closed-ended. For example, "include" and "comprising" may mean that other components not listed may also be included or that only the listed components are included.

[0033] An embodiment of the first aspect of the present invention provides a combustion improver, which includes the following raw materials, in parts by mass: 3-7 parts of nano-cerium oxide, 10-20 parts of potassium nitrate, 8-15 parts of iron oxide, 40-60 parts of modified diatomaceous earth, 10-20 parts of sodium carboxymethyl cellulose, 1-5 parts of zinc borate, and 1-3 parts of sodium dodecylbenzene sulfonate.

[0034] The particle size of the nano-cerium oxide is 20-50 nm. The mass fraction of the nano-cerium oxide is any value selected from 3 parts, 4 parts, 5 parts, 6 parts, and 7 parts, or any combination of these values. A mass fraction of nano-cerium oxide exceeding 7 parts leads to excessive cost and no significant improvement in combustion efficiency. A mass fraction of nano-cerium oxide below 3 parts leads to insufficient catalytic effect and fails to effectively promote coal combustion.

[0035] The modified diatomite modification method comprises the following steps: calcining the diatomite at 600-650° C. for 1-3 hours to remove organic impurities and increase porosity so as to optimize the pore size distribution to 10-50 nm; placing the calcined diatomite in a ball mill and ball milling using zirconium oxide grinding balls at a ball-to-material ratio of 5:1 until the diatomite particle size is 200-250 meshes, thereby obtaining the modified diatomite.

[0036] The modified diatomaceous earth has a pore size of 10-50 nm. Modified diatomaceous earth within this pore size range can effectively load and slowly release active ingredients, improving the stability and durability of the combustion aid. The modified diatomaceous earth content can be any number or combination of 40, 45, 50, 55, or 60 parts by weight. If the modified diatomaceous earth content is too high, the combustion aid may become too viscous, hindering its dispersion and application. If the content is too low, the active ingredients may not be fully loaded, affecting the combustion-supporting effect.

[0037] The mass fraction of the potassium nitrate is 10-20 parts. Potassium nitrate can provide good oxidation performance within this range and promote the combustion of coal. The mass fraction of potassium nitrate can be any value or any combination of values ​​among 10 parts, 12 parts, 15 parts, 18 parts, and 20 parts. Too much mass fraction of potassium nitrate may cause the combustion aid to be too active, which may easily cause safety hazards; too little mass fraction of potassium nitrate may not provide sufficient oxidation performance, affecting the combustion-supporting effect.

[0038] The iron oxide is present in an amount of 8-15 parts by weight. Iron oxide acts as an electron donor, synergistically interacting with nano-cerium oxide during combustion to promote the combustion chain reaction. The iron oxide can be present in an amount of 8, 10, 12, 14, or 15 parts by weight, or in any combination thereof. An appropriate amount of iron oxide can significantly improve combustion efficiency.

[0039] The mass fraction of the sodium carboxymethyl cellulose is 10-20 parts. The addition of sodium carboxymethyl cellulose enhances the cohesiveness and formability of the combustion aid, making the granulation process smoother. The mass fraction of sodium carboxymethyl cellulose can be any value or any combination of values ​​among 10 parts, 12 parts, 15 parts, 18 parts, and 20 parts. An appropriate amount of sodium carboxymethyl cellulose can ensure the stability and ease of processing of the combustion aid; too little may make it difficult to form the combustion aid, affecting the use effect.

[0040] The synergistic effect of the components in the combustion-supporting agent formula of the present invention not only improves the combustion efficiency of coal, but also significantly prolongs the release cycle of the active components of the combustion-supporting agent. Among them, the composite of nano-cerium oxide and potassium nitrate, the pre-composite active powder formed by spray drying, has excellent catalytic performance, can effectively reduce the ignition point of coal, and accelerate the combustion speed; modified diatomaceous earth is used as a carrier, and its unique pore structure is conducive to the uniform dispersion and slow release of active components, thereby improving the stability of the combustion-supporting agent; in addition, nano-cerium oxide serves as an electron acceptor and iron oxide serves as an electron donor. During the combustion process, the electron transfer between the two promotes the progress of the combustion chain reaction, thereby improving the combustion efficiency. Potassium nitrate is embedded in the pores of the modified diatomaceous earth to achieve gradient release; at the same time, the rare earth properties of nano-cerium oxide are combined with the transition metal properties of iron oxide, and through synergistic catalysis, the combustion efficiency of coal is effectively improved and the emission of harmful gases is reduced; the addition of sodium carboxymethyl cellulose enhances the adhesiveness and formability of the combustion-supporting agent, making the granulation process smoother; zinc borate and sodium dodecylbenzene sulfonate respectively play the role of flame retardancy and dispersion, further improving the comprehensive performance of the combustion-supporting agent.

[0041] The embodiment of the second aspect of the present application provides a method for preparing a combustion improver, comprising the following steps:

[0042] S1: mixing potassium nitrate and nano-cerium oxide and spray drying to obtain a pre-composite active powder;

[0043] S2: mixing modified diatomaceous earth, sodium carboxymethyl cellulose, pre-compounded active powder, iron oxide, zinc borate, and sodium dodecylbenzenesulfonate to obtain a mixed material;

[0044] S3: granulating and coating the mixed material.

[0045] In step S1, potassium nitrate is dissolved in water to obtain a potassium nitrate solution with a mass concentration of 28-30%, and then nano-cerium oxide powder is added and ultrasonically dispersed for 30-40 minutes to obtain a mixed solution. The frequency of the ultrasonic dispersion is 40-50 kHz.

[0046] The mixed liquid is spray-dried, wherein the inlet temperature of the spray-drying is 160-190° C. and the outlet temperature of the spray-drying is 70-90° C., to obtain pre-composite active powder.

[0047] In step S2, the diatomaceous earth needs to be modified before mixing. The modification method is as follows: calcining the diatomaceous earth at 600-650°C for 1-3 hours to remove organic impurities and increase the porosity to optimize the pore size distribution to 10-50 nm. The calcined diatomaceous earth is put into a ball mill and ball-milled using zirconium oxide grinding balls at a ball-to-material ratio of 5:1 until the diatomaceous earth particle size is 200-250 mesh, thereby obtaining modified diatomaceous earth.

[0048] In step S2, modified diatomaceous earth, sodium carboxymethyl cellulose, pre-composite active powder, iron oxide, zinc borate, and sodium dodecylbenzenesulfonate are sequentially added to a biaxial paddle mixer at a speed of 700-850 rpm; the mixing temperature is 50-60° C. to prevent premature decomposition of potassium nitrate; and the mixing time is 20-30 minutes to ensure uniform dispersion of the components.

[0049] The granulation in step S3 is to spray an adhesive into the mixed material, wherein the adhesive is 4-6 parts by mass of a polyvinyl alcohol (PVA) solution (concentration 10wt%), and the adhesive spray rate is 0.4-0.6L / min; the mixed material is simultaneously fed into a fluidized bed dryer to form particles, and the inlet air temperature of the fluidized bed granulation is 75-85°C and the wind speed is 1.1-1.5m / s; the particle size of the formed particles is controlled to be 0.5-1.5mm.

[0050] Furthermore, before coating the particles in step S3, a 20-mesh vibrating screen is used to remove oversized or overfine particles, and then the particles are coated with fumed silica.

[0051] The sieved particles were placed in a rotary coating machine and evenly sprayed with a fumed silica suspension having a solid content of 5% to form a silica coating layer with a thickness of ≤50 μm on the particle surface. After coating, secondary drying was performed by circulating hot air at 60°C for 1 hour.

[0052] Example 1

[0053] A combustion improver comprises the following raw materials, in parts by mass: 5 parts of nano-cerium oxide, 15 parts of potassium nitrate, 10 parts of iron oxide, 50 parts of modified diatomaceous earth, 15 parts of sodium carboxymethyl cellulose, 3 parts of zinc borate, and 2 parts of sodium dodecylbenzene sulfonate.

[0054] Example 2

[0055] A combustion improver comprises the following raw materials, in parts by mass: 3-7 parts of nano-cerium oxide, 12 parts of potassium nitrate, 8 parts of iron oxide, 60 parts of modified diatomaceous earth, 18 parts of sodium carboxymethyl cellulose, 1 part of zinc borate, and 3 parts of sodium dodecylbenzene sulfonate.

[0056] Example 3

[0057] A combustion improver comprises the following raw materials, in parts by mass: 3-7 parts of nano-cerium oxide, 10 parts of potassium nitrate, 15 parts of iron oxide, 55 parts of modified diatomaceous earth, 10 parts of sodium carboxymethyl cellulose, 5 parts of zinc borate, and 2.5 parts of sodium dodecylbenzene sulfonate.

[0058] Example 4

[0059] A combustion improver comprises the following raw materials, in parts by mass: 3-7 parts of nano-cerium oxide, 20 parts of potassium nitrate, 12 parts of iron oxide, 40 parts of modified diatomaceous earth, 20 parts of sodium carboxymethyl cellulose, 4 parts of zinc borate, and 1 part of sodium dodecylbenzene sulfonate.

[0060] Example 5

[0061] A method for preparing a combustion improver comprises the following steps:

[0062] S1: Potassium nitrate is dissolved in water to obtain a potassium nitrate solution with a mass concentration of 28-30%, and then nano-cerium oxide powder is added and ultrasonically dispersed for 30 minutes to obtain a mixed solution. The frequency of the ultrasonic dispersion is 40 kHz;

[0063] The mixed solution was spray-dried at an inlet temperature of 180° C. and an outlet temperature of 85° C. to obtain a pre-composite active powder;

[0064] S2: Modifying the diatomite by calcining the diatomite at 600° C. for 2 hours to remove organic impurities and increase porosity, optimizing the pore size distribution to 10-50 nm. The calcined diatomite is placed in a ball mill using zirconia grinding balls at a ball-to-material ratio of 5:1, and ball milling is performed until the diatomite particle size is 200-250 mesh, thereby obtaining modified diatomite.

[0065] The modified diatomaceous earth, sodium carboxymethyl cellulose, pre-composite active powder, iron oxide, zinc borate, and sodium dodecylbenzenesulfonate in Example 1 were sequentially added to a biaxial paddle mixer at a speed of 800 rpm; the mixing temperature was 60° C. to prevent premature decomposition of potassium nitrate; and the mixing time was 30 min to ensure uniform dispersion of the components to obtain a mixed material.

[0066] S3: Spraying a binder of 5 parts by mass of a polyvinyl alcohol (PVA) solution (10 wt%) into the mixed material at a spray rate of 0.5 L / min; simultaneously entering a fluidized bed dryer to form granules; the fluidized bed granulation air inlet temperature of the fluidized bed granulation is 80°C and the wind speed is 1.5 m / s; the particle size of the formed granules is controlled to be 0.5-1.5 mm;

[0067] Before coating the particles, a 20-mesh vibrating screen is used to remove oversized or overfine particles. The screened particles are placed in a rotary coating machine and evenly sprayed with a fumed silica suspension with a solid content of 5%. A silica coating layer with a thickness of ≤50μm is formed on the surface of the particles. After coating, secondary drying is performed in a hot air circulation at 60°C for 1h.

[0068] Example 6

[0069] This embodiment is basically the same as embodiment 5, except that the inlet temperature of the spray drying in step S1 is 170°C; the outlet temperature of the spray drying is 70°C.

[0070] Example 7

[0071] This embodiment is basically the same as embodiment 5, except that the mixing speed in step S2 is 750 rpm, the temperature is 55° C., and the time is 20 min.

[0072] Example 8

[0073] This embodiment is basically the same as embodiment 5, except that the inlet air temperature of the fluidized bed granulation in step S3 is 85° C. and the wind speed is 1.3 m / s.

[0074] Example 9

[0075] This embodiment is basically the same as embodiment 5, except that the raw materials in embodiment 2 are used in step S2.

[0076] Comparative Example 1

[0077] This embodiment is basically the same as embodiment 5, except that the raw materials do not contain nano-cerium oxide.

[0078] Comparative Example 2

[0079] This embodiment is substantially the same as Example 5, except that the mass fraction of potassium nitrate in the raw material is 25 parts.

[0080] Comparative Example 3

[0081] This embodiment is basically the same as embodiment 5, except that sodium carboxymethyl cellulose is replaced with starch binder.

[0082] Comparative Example 4

[0083] This embodiment is basically the same as embodiment 5, except that the modified diatomaceous earth is replaced by ordinary kaolin.

[0084] Comparative Example 5

[0085] This embodiment is basically the same as embodiment 5, except that in step S2, modified diatomaceous earth, sodium carboxymethyl cellulose, pre-composite active powder, iron oxide, zinc borate, and sodium dodecylbenzenesulfonate are put into a biaxial paddle mixer at a mixing temperature of 80°C.

[0086] Comparative Example 6

[0087] This embodiment is basically the same as embodiment 5, except that the particles are not subjected to silica vapor coating in step S3.

[0088] The combustion improvers prepared in Examples 5-9 and Comparative Examples 1-6 were subjected to performance tests, wherein the coal saving rate was tested according to the combustion-supporting effect evaluation method of coal combustion improvers in GB / T31097-2014; under the same operating conditions, the combustion improver was mixed with pulverized coal (1:10), and the time from the flame lasting until it went out after ignition was recorded. The results are shown in the following table:

[0089]

[0090]

[0091] As can be seen from the above table, the combustion improver obtained by the present invention adopts specific components and proportions, and undergoes a specific preparation process, which is significantly improved in terms of coal saving rate and release time compared to the comparative example. In Example 5, the coal saving rate reached 18.7%, and the release time was 240min, compared with the coal saving rate of 12.3% and the release time of 90min in Comparative Example 1 (without nano-cerium oxide), and the coal saving rate of 9.7% and the release time of 40min in Comparative Example 4 (modified diatomaceous earth is replaced by ordinary kaolin), it can be seen that the combustion improver of the present invention has significant advantages in improving combustion efficiency and extending the release cycle. In addition, Examples 6-9 also showed good coal saving effects and longer release times, which further verified the effectiveness and stability of the combustion improver of the present invention.

[0092] Comparative Example 1 does not contain nano-cerium oxide, and the coal saving rate and release time are greatly reduced. The reason is that the catalytic effect of nano-cerium oxide is lacking, resulting in insufficient combustion chain reaction, and the combustion efficiency of coal fails to be effectively improved. At the same time, the release period of the active component is also shortened accordingly. The mass fraction of potassium nitrate in Comparative Example 2 is too high. Although it provides sufficient oxidation performance, it may cause the combustion improver to be too active, the combustion process is difficult to control, and the release time is too long, which is not conducive to practical application. In Comparative Example 3, sodium carboxymethyl cellulose is replaced by starch binder, and the adhesion and formability are weakened, the stability of the combustion improver is reduced, and it is easy to cause incomplete combustion and a decrease in the coal saving rate. In Comparative Example 4, modified diatomaceous earth is replaced by ordinary kaolin. Since the pore structure of ordinary kaolin is not conducive to the uniform dispersion and slow release of active components, the combustion improver effect is greatly reduced. In Comparative Example 5, the mixing temperature is too high, which may cause potassium nitrate to decompose prematurely, affecting the performance of the combustion improver. In Comparative Example 6, the particles are not subjected to silica vapor coating, the stability and durability of the combustion improver are weakened, and the release time is shortened.

[0093] In summary, the combustion improver of the present invention achieves the dual advantages of efficient combustion and sustained release through carefully designed component ratios and preparation processes, and has significant application value.

[0094] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A combustion improver, characterized in that: The preparation comprises the following raw materials in parts by mass: 3-7 parts of nano-cerium oxide, 10-20 parts of potassium nitrate, 8-15 parts of iron oxide, 40-60 parts of modified diatomaceous earth, 10-20 parts of sodium carboxymethyl cellulose, 1-5 parts of zinc borate and 1-3 parts of sodium dodecylbenzene sulfonate.

2. The combustion improver according to claim 1, characterized in that The particle size of the nano-cerium oxide is 20-50 nm.

3. The combustion improver according to claim 1, characterized in that The pore size of the modified diatomaceous earth is 10-50 nm.

4. A method for preparing the combustion improver according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1: mixing potassium nitrate and nano-cerium oxide and spray drying to obtain a pre-composite active powder; S2: mixing modified diatomaceous earth, sodium carboxymethyl cellulose, pre-compounded active powder, iron oxide, zinc borate, and sodium dodecylbenzenesulfonate to obtain a mixed material; S3: granulating and coating the mixed material.

5. The method for preparing the combustion improver according to claim 4, wherein: In step S1, potassium nitrate is dissolved in water to obtain a potassium nitrate solution with a mass concentration of 28-30%, and then nano-cerium oxide powder is added and ultrasonically dispersed for 30-40 minutes to obtain a mixed solution; and / or The frequency of the ultrasonic dispersion is 40-50 kHz.

6. The method for preparing the combustion improver according to claim 4, wherein: The inlet temperature of the spray drying in step S1 is 160-190°C; and / or The outlet temperature of the spray drying is 70-90°C.

7. The method for preparing the combustion improver according to claim 4, characterized in that: The modification method of the modified diatomaceous earth in step S2 is: calcining the diatomaceous earth at 600-650° C. and then ball milling; and / or The calcination time is 1-3h; and / or Ball mill the diatomaceous earth to a particle size of 200-250 mesh.

8. The method for preparing the combustion improver according to claim 4, wherein: The mixing speed in step S2 is 700-850 rpm; and / or The mixing temperature is 50-60°C; and / or The mixing time is 20-30 minutes.

9. The method for preparing the combustion improver according to claim 4, characterized in that: The granulation in step S3 is to spray a binder into the mixed material and simultaneously enter the fluidized bed dryer to form granules; and / or The spraying rate of the adhesive is 0.4-0.6 L / min; and / or The inlet air temperature of the fluidized bed granulation is 75-85°C; and / or The wind speed of the fluidized bed granulation is 1.1-1.5 m / s.

10. The method for preparing the combustion improver according to claim 4, characterized in that: The coating in step S3 is performed by spraying a fumed silica suspension into the particles to form a silica coating layer with a thickness of ≤50 μm on the surface of the particles, followed by drying.

Images