Water-based combustion improver, preparation method and application

Abstract

The invention relates to a water-based combustion improver, a preparation method and application. The water-based combustion improver comprises plant polyphenol, nano cellulose and metal salt. The invention also provides a preparation method of the water-based combustion improver, which comprises the following steps: dissolving the plant polyphenol in a solvent, then adding the nanocellulose, heating to a preset temperature, then adding the high-molecular polymer, and continuously heating and stirring to obtain a suspension, namely a plant polyphenol modified nanocellulose solution; and adding metal salt into the suspension to obtain the water-based combustion improver. The invention also provides application of the water-based combustion improver as a coal gangue combustion improver. The coal gangue combustion improver solves the problem that an existing coal gangue combustion improver needs to be added with a strong oxidizing agent, so that explosion and danger are caused, and also solves the problems that the existing coal gangue combustion improver is large in usage amount and high in cost.

Description

Technical Field

[0001] The present invention relates to the technical field of combustion aids, and particularly to an aqueous combustion aid, a preparation method and an application thereof. Background Art

[0002] Coal gangue is a solid waste generated during coal mining and washing processes, mainly composed of carbonaceous shale, mudstone, sandstone and a small amount of coal, etc. It has the characteristics of low carbon content, harder texture than coal, and dry basis ash content greater than 50%. The generation of coal gangue runs through all links of coal mine production, including heading gangue during roadway driving, gangue mined from the roof, floor and interlayers during mining, and washery gangue picked out during coal washing.

[0003] For a long time, the treatment methods of coal gangue have been relatively extensive, and some treatment methods even sacrifice the environment. For example, pulverizing coal gangue and doping it into raw coal for sale as boiler fuel will not only cause excessive emissions and seriously pollute the atmospheric environment, but also essentially just transfer coal gangue from one storage yard to another, without fundamentally solving its potential harm to the environment. In addition, coal gangue contains sulfides, and these substances will escape or leach out in the natural environment, thus polluting the atmosphere, farmland and water sources. Even more worryingly, the carbon in coal gangue can spontaneously combust under certain conditions, causing fires and releasing a large amount of toxic and harmful gases, such as carbon monoxide (CO), sulfur dioxide (SO 2 ), hydrogen sulfide (H 2 S), etc., posing a serious threat to the ecological environment and the health of residents in the mining area and its surrounding areas.

[0004] With the continuous enhancement of people's awareness of energy conservation and environmental protection, the problem of a large amount of coal gangue piled up in the mining area has gradually attracted extensive attention from all sectors of society. The reasonable treatment and utilization of coal gangue not only concern environmental protection, but also involve the sustainable utilization of resources. Since the 1960s, many countries have begun to pay attention to the treatment and utilization of coal gangue. At present, the application of coal gangue as fuel mainly focuses on fields such as melting iron, burning boilers, and burning lime, but these application methods all require the addition of combustion aids and strong oxidants, such as sodium nitrate, potassium nitrate, ammonium nitrate, etc., and these substances are explosive and dangerous. In addition, the addition amount of the combustion aid often exceeds 5%, which not only increases the dosage and cost, but also the existing combustion aids are mostly solid or slurry, making them extremely inconvenient to use. In addition, it has also been found that coal gangue power generation, as an important way to effectively utilize the heat energy of coal gangue and realize waste resourceization, can significantly reduce environmental pollution. However, coal gangue is harder and has a lower carbon content than ordinary coal, making it difficult to burn. The application effect of traditional coal combustion aids on coal gangue is not ideal, resulting in low combustion efficiency and low utilization rate. Therefore, there is an urgent need to develop a more scientific, environmentally friendly and efficient combustion aid, as well as coal gangue treatment and utilization technologies. Summary of the Invention

[0005] In view of this, the object of the present invention is to provide an aqueous combustion improver, a preparation method and an application thereof, so as to solve the problems that the existing coal gangue combustion improver needs to add a strong oxidant, resulting in explosion and danger, and can also solve the problems of large consumption and high cost of the existing coal gangue combustion improver, as well as the inconvenient use of the existing coal gangue combustion improver.

[0006] In order to achieve the above object, the technical scheme adopted by the present invention is as follows: An aqueous combustion improver, comprising plant polyphenols, nano-cellulose, metal salts and a solvent.

[0007] Among them, the applicant of this case found in the experimental research process that plant polyphenols are a class of natural compounds widely existing in plants, containing multiple phenolic hydroxyl groups, and these groups can form coordination bonds with iron ions. Especially catechol and pyrogallol groups, which can form stable complexes with metal ions such as iron ions, and the formed polyphenol-iron complexes have high stability. At the same time, plant polyphenols are biomass with a high carbon content. Since they start to lose weight and decompose at 200 °C to produce volatile combustion-supporting substances such as CO, CH 4 , volatile organic compounds, etc., therefore, using it as a combustion improver can make up for the loss in the early stage of the combustion improver. When polyphenols are decomposed by heat, expanded coke will be generated. Since it is evenly dispersed in the fuel, it can increase the overall porosity of the fuel, enabling the internal fixed carbon to react fully with oxygen and burn. Polyphenols can also act as a catalyst for the combustion improver. It can form a stable complex with metal ions, enhance the catalytic performance of metal oxides, thereby activating metal oxides and enhancing their catalytic performance.

[0008] Nano-cellulose is a nano-scale particle composed of cellulose molecules, and its size is usually between 1 and 100 nanometers. It is derived from natural plant cellulose such as wood, cotton, and rice husks, and is a natural polymer widely existing in plant cell walls. Nano-cellulose acts as a carrier for the catalyst in the aqueous combustion improver, loading metals, effectively promoting the combustion of coal gangue, reducing the activation energy of the reaction, and accelerating the reaction rate.

[0009] In the combustion process of coal gangue briquettes, it is very important to increase the pores and surface area in the particles, because this helps to improve the reactivity and combustion efficiency of coal gangue briquettes. Therefore, through long-term research, it is found that by adding metal salts as catalysts to the aqueous combustion improver, the combustion-supporting effect of coal gangue can be significantly improved.

[0010] Preferably, it includes nano-cellulose modified by plant polyphenols, metal salts and a solvent; The metal salts include iron salts, copper salts, calcium salts and sodium salts.

[0011] By selecting a mixture of iron salts, copper salts, calcium salts, and sodium salts as the mixed metal salts and adding them to the aqueous combustion aid, under high-temperature conditions, chemical reactions will occur among the metal salts to form corresponding metal oxides. Then, through the synergistic effect among the metal oxides, the combustion process can be catalyzed, the reaction efficiency can be improved, and the effect of the overall combustion aid can be enhanced.

[0012] Among them, as an iron-based catalyst, the iron salt added to the aqueous combustion aid can promote the breakage of oxygen-containing groups and reduce the oxygen content in the semicoke, not only increasing the porosity of the semicoke but also increasing the specific surface area and pore volume.

[0013] In the aqueous combustion aid, the presence of sodium salts can change the reactivity of coal gangue, affect its thermal reaction process and the emission of nitrogen oxides. In addition, the addition of sodium can also promote the generation of NH 3 during the pyrolysis of coal gangue and reduce the generation of NO x precursors, which is of great significance in reducing environmental pollution.

[0014] In the aqueous combustion aid, as a copper-based catalyst, the copper salt can lower the ignition temperature of coal gangue, improve the combustion efficiency, and thus increase the combustion rate and heat release of coal gangue.

[0015] In the aqueous combustion aid, the iron salt not only acts as a combustion aid but also has the effect of a sulfur-fixing agent. At the same time, the presence of calcium salts effectively realizes the fixation of sulfur in coal gangue. Therefore, as a sulfur-fixing agent, calcium salts can significantly reduce the emission of sulfides.

[0016] Preferably, the iron salt is selected from at least one of ferric chloride, ferric nitrate, ferric sulfate, ferric phosphate, ferrocene, ferrous chloride, ferrous nitrate, and ferrous sulfate.

[0017] Preferably, the copper salt is selected from at least one of copper sulfate, copper nitrate, copper chloride, copper acetate, and copper carbonate.

[0018] Preferably, the calcium salt is selected from at least one of calcium chloride, calcium oxide, calcium hydroxide, calcium phosphate, calcium acetate, and calcium citrate.

[0019] Preferably, the calcium salt is selected from a mixture of calcium oxide and calcium hydroxide.

[0020] While the mixture of calcium oxide and calcium hydroxide acts as a sulfur-fixing agent, calcium hydroxide can also react with carbon dioxide to form calcium carbonate, thereby reducing the lattice melting point of silicon dioxide in coal gangue and further improving the overall combustion performance of coal gangue.

[0021] Preferably, the sodium salt is selected from at least one of sodium chloride, sodium humate, sodium formate, sodium sulfate, disodium hydrogen phosphate, and sodium citrate.

[0022] Preferably, the plant polyphenol is selected from at least one of tea polyphenols, gallic acid, catechol, ellagic acid, catechins, tannic acid, larch tannin, myrica tannin, acacia mearnsii de wild tannin, and persimmon tannin.

[0023] The present invention also provides a preparation method of the aqueous combustion aid as described in the present invention, comprising the following steps: S1. Dissolve the plant polyphenol in a solvent, then add nanocellulose, and after heating to a preset temperature, add a high molecular polymer, and continue heating and stirring to obtain a suspension, namely a nanocellulose solution modified with plant polyphenols; S2. Add a metal salt to the suspension to obtain the aqueous combustion aid.

[0024] Among them, by adding a high molecular polymer, the ignition point is further reduced, the combustion process is accelerated, and the heat loss of incomplete combustion is reduced; the addition of the high molecular polymer can also reduce pollutants generated during the combustion process, such as sulfur dioxide and nitrogen oxides, etc., reduce environmental pollution, and can improve the efficiency of the combustion aid, reduce the usage amount of the combustion aid, thereby reducing production costs.

[0025] Preferably, the preset temperature is 25 - 60 °C.

[0026] Preferably, the high molecular polymer is selected from at least one of PEG200 (polyethylene glycol 200), PEG400 (polyethylene glycol 400), PEG600 (polyethylene glycol 600), PEG1000 (polyethylene glycol 1000), PEG20000 (polyethylene glycol 20000), PVA1788 (polyvinyl alcohol 1788), PVA2488 (polyvinyl alcohol 2488), PAM - 3M (polyacrylamide - 3M), PAM - 8M (polyacrylamide - 8M), PVP K30 (polyvinylpyrrolidone K30), PVP K90 (polyvinylpyrrolidone K90), CMC - Na - 220 (sodium carboxymethyl cellulose 220), CMC - Na - 450 (sodium carboxymethyl cellulose 450), PEO - 100K (polyethylene oxide 100K), PEO - 300K (polyethylene oxide 300K), PAAS - 5000 (sodium polyacrylate 5000), PAAS - 10000 (sodium polyacrylate 10000), and mPEG2000 (methoxypolyethylene glycol 2000).

[0027] Preferably, the solvent is selected from at least one of water, ethanol, and ethylene glycol.

[0028] Preferably, in the suspension, the mass percentage content of the plant polyphenol is 5 - 15%, the mass percentage content of the nanocellulose is 3 - 10%, and the mass percentage content of the high molecular polymer is 30 - 60%; Preferably, the metal salt includes iron salt, copper salt, calcium salt and sodium salt, and the suspension, iron salt, copper salt, calcium salt and sodium salt are 10-30 parts, 5-20 parts, 5-15 parts, 3-10 parts and 5-15 parts by weight; Preferably, the S2 includes: adding a metal salt to the suspension and adjusting the viscosity to (20±3) mPa·s with water to obtain an aqueous combustion aid.

[0029] The present invention also provides an application of the aqueous combustion aid as a combustion aid for coal gangue.

[0030] During the use of the aqueous combustion aid of the present invention as a combustion aid for coal gangue, since it is aqueous, during the process of making coal gangue briquettes, it can be sprayed with water dilution, which is convenient and simple to use.

[0031] Preferably, when the aqueous combustion aid is used as a combustion aid for coal gangue, no oxidant needs to be added.

[0032] During the use of the aqueous combustion aid of the present invention as a combustion aid for coal gangue, no strong oxidant or other reagents need to be added. Compared with adding chemicals such as explosive strong oxidants, the safety performance is greatly improved.

[0033] Preferably, the addition amount of the aqueous combustion aid as a combustion aid for coal gangue is ≤0.1%.

[0034] During the use of the aqueous combustion aid of the present invention as a combustion aid for coal gangue, only 0.1% needs to be added, which can reduce the ignition point of coal gangue, accelerate the combustion rate of combustible substances, reduce the amount of residues after combustion, extend the combustion time, make the combustion more complete, improve the combustion efficiency, and thus has the advantages of less dosage, low cost and reduced pollutant emissions.

[0035] Among them, during the use of the aqueous combustion aid of the present invention as a combustion aid for coal gangue, the plant polyphenol-modified nanocellulose solution and metal oxide act repeatedly on the surface and inside of coal gangue through penetration, catalysis, oxidation, metal ion exchange, etc., effectively reducing the activation energy of the carbon oxidation reaction, thereby reducing the ignition point of coal.

[0036] The beneficial effects of the present invention: The aqueous combustion aid of the present invention uses plant polyphenol-modified nanocellulose and metal salt as raw materials. The components do not contain explosive substances, ensuring the use safety. The combustion aid is aqueous, which is convenient for use. Moreover, as a combustion aid, the usage amount is small, effectively reducing the cost and reducing the pollutant emissions.

[0037] The water-based combustion aid of the present invention is used as a combustion aid in coal gangue, which can significantly reduce the ignition point of coal gangue, accelerate the combustion rate of combustible substances, reduce the mass of residues after combustion, extend the combustion time, make the combustion more complete, improve the combustion efficiency, and is easy to operate. It can be mixed with water in proportion during the coal washing process and directly sprayed on coal or coal gangue. Thus, it can not only improve the utilization efficiency of coal gangue, reduce environmental pollution, and lower the coal combustion cost, but also is expected to bring a revolutionary change to the coal industry and achieve a win-win situation between economic benefits and environmental protection. It has the value of popularization and application in the field of combustion aid technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 TG curve and DTG curve of the coal sample; Figure 2 TG curve and DTG curve of the coal sample added with the water-based combustion aid in Example 1; Figure 3 TG curve and DTG curve of the coal gangue sample Figure 1 ; Figure 4 TG curve and DTG curve of the coal gangue sample added with the water-based combustion aid in Example 1; Figure 5 TG curve and DTG curve of the coal gangue sample Figure 2 ; Figure 6 TG curve and DTG curve of the coal gangue sample added with the water-based combustion aid in Example 3. DETAILED DESCRIPTION OF THE INVENTION

[0039] The following will illustrate the implementation manners of the present invention with reference to the preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. The details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for illustrating the present invention and not for limiting the protection scope of the present invention.

[0040] Example 1 A preparation method of a water-based combustion aid includes the following steps: S1. Dissolve 3 g of tannic acid in 20 g of water, then add 3 g of nanocellulose powder to obtain a mixed system. After heating the mixed system to 40 °C, add 30 g of a mixture of PEG200 and PEG1000, and continue to stir at 40 °C until a homogeneous suspension is formed to obtain a tannic acid-modified nanocellulose solution. Among them, in the mixture, the mass ratio of PEG200 to PEG1000 is 3:1; S2. Mix 50 g of tannic acid-modified nanocellulose solution, 5 g of ferric chloride, 3 g of copper acetate, 3 g of calcium phosphate, and 5 g of sodium sulfate, then stir at a speed of 1000 r / min for 40 min, and then adjust the viscosity to (20 ± 3) mPa·s with deionized water to obtain an aqueous combustion aid.

[0041] Example 2 A preparation method of an aqueous combustion aid, comprising the following steps: S1. Dissolve 5 g of myricetin tannin in 30 g of water, then add 4 g of nanocellulose powder to obtain a mixed system. After heating the mixed system to 60 °C, add 20 g of a mixture of PEG600 and PEG20000, and continue to stir at 60 °C until a homogeneous suspension is formed to obtain myricetin tannin-modified nanocellulose solution, wherein, in the mixture, the mass ratio of PEG600 to PEG20000 is 10:1; S2. Mix 40 g of myricetin tannin-modified nanocellulose solution, 10 g of ferric sulfate, 5 g of copper nitrate, 3 g of calcium chloride, and 10 g of sodium humate, then stir at a speed of 1000 r / min for 50 min, and then adjust the viscosity to (20 ± 3) mPa·s with deionized water to obtain an aqueous combustion aid.

[0042] Example 3 A preparation method of an aqueous combustion aid, comprising the following steps: S1. Dissolve 8 g of catechol in 30 g of water, then add 5 g of nanocellulose powder to obtain a mixed system. After heating the mixed system to 60 °C, add 25 g of a mixture of PEG200 and PEG400, and continue to stir at 60 °C until a homogeneous suspension is formed to obtain catechol-modified nanocellulose solution, wherein, in the mixture, the mass ratio of PEG200 to PEG400 is 3:1; S2. Mix 50 g of catechol-modified nanocellulose solution, 12 g of ferrous nitrate, 5 g of copper sulfate, 4 g of calcium chloride, and 8 g of sodium chloride, then stir at a speed of 1000 r / min for 30 min, and then adjust the viscosity to (20 ± 3) mPa·s with deionized water to obtain an aqueous combustion aid.

[0043] Example 4 A preparation method of an aqueous combustion aid, comprising the following steps: S1. Dissolve 6 g of tea polyphenols in 40 g of water, then add 4 g of nanocellulose powder to obtain a mixed system. After heating the mixed system to 60 °C, add 50 g of PEG400, and continue to stir at 60 °C until a homogeneous suspension is formed to obtain tea polyphenol-modified nanocellulose solution; S2. Mix 50 g of nano-cellulose solution modified with tea polyphenols, 15 g of ferric nitrate, 5 g of copper nitrate, 3 g of calcium acetate, and 10 g of sodium formate, stir at a speed of 1000 r / min for 30 min, and then adjust the viscosity to (20±3) mPa·s with deionized water to obtain an aqueous combustion aid.

[0044] Thermogravimetric analysis test (1) Tests on coal samples and coal samples with combustion aid (the coal used has a calorific value of 5500 kcal, the combustion aid is the aqueous combustion aid prepared in Example 1, and the addition amount is 0.1 wt%). The specific operation steps are as follows: 1) Crushing: Prepare a certain amount and a certain particle size (about 1 mm) of coal samples according to the sample preparation standard requirements. 2) Weighing: Weigh 105 g of coal samples and 0.105 g of the aqueous combustion aid in Example 1 with an analytical balance and put them into crucibles respectively. 3) Stirring: Stir the samples in the crucible for about 5 minutes to make the coal samples and the aqueous combustion aid fully mixed, then put them into a sample bag and label. 4) Sample preparation: Crush the above samples into a particle size of 100 mesh to 200 mesh required for thermogravimetric combustion. 5) Sampling: Dry the samples in step 4, and measure them with a thermogravimetric analyzer. Weigh 5 mg of the dried samples for each test, and use the dried coal samples without adding any combustion aid as a control.

[0045] Among them, a thermogravimetric analyzer produced by Netzsch of Germany is used for thermogravimetric combustion test. The conditions of the thermogravimetric combustion test are: under air conditions, the air flow rate is 50 mL / min, the temperature is programmed to rise from room temperature to 1000 °C at a heating rate of 10 °C / min. Synchronously record the TG (thermogravimetric) and DTG (differential thermogravimetric) curves, and analyze the combustion characteristic parameters (ignition temperature, burnout temperature, maximum weight loss rate, etc.). The results are as Figure 1 and Figure 2 shown.

[0046] Figure 1 The solid line in Figure 1 is the TG curve of the coal sample.

[0047] Figure 2 The solid line in Figure 2 is the TG curve of the sample after adding the aqueous combustion aid in Example 1 to the coal.

[0048] From Figure 1 the TG curve of the coal sample in Figure 2From the comparative analysis of the TG curves of the coal sample and the sample of coal with the water-based combustion aid in Example 1, the initial temperature is 35°C. During the whole experiment, the stages where the weight loss of the two samples changes significantly are concentrated in the temperature range of 300-450°C. In this temperature range, the weight loss of the samples is relatively high. The reason should be that the volatilization points or ignition points of the available substances in the samples within 1000°C are in this temperature range, resulting in a significant change in weight. For the coal sample, when the temperature reaches 402.03°C, the curve drops rapidly. For the sample of coal with the water-based combustion aid, when the temperature reaches 390.44°C, the curve drops rapidly. The test results show that adding the combustion aid can reduce the combustion peak temperature of coal by about 12°C. When the temperature rises to 1000°C, the samples remain 4.862% and 2.979% respectively. This proves that the sample with the water-based combustion aid can better reduce the starting combustion temperature, extend the combustion time, and burn more fully.

[0049] From Figure 1 the DTG curve of the coal sample in Figure 2 and the comparative analysis of the DTG curve of the sample of coal with the water-based combustion aid in Example 1, it can be seen that when the temperature rises continuously, the weight loss rate of the sample also changes continuously. For the coal sample without the water-based combustion aid, the curve starts to drop sharply after 380°C, reaches the lowest point at about 427.68°C, then starts to rise, and the curve becomes flat after 500°C, with a weight loss rate of 40.672% / min per minute. For the sample with the water-based combustion aid, the curve starts to drop sharply after 370°C, reaches the lowest point at about 437.45°C, then starts to rise, and the curve becomes flat after 510°C, with a weight loss rate of 18.622% / min per minute. When the curve width returns to being flat, it proves that the combustion is complete.

[0050] The DTG curve shows that the sample with the water-based combustion aid has a longer half-peak width, a longer combustion time, and burns more fully. This proves that the coal sample with the water-based combustion aid burns more fully and can better improve the combustion efficiency of coal.

[0051] (2) Testing of the coal gangue sample and the coal gangue sample with the combustion aid (the coal gangue used has a calorific value of 700 kcal, the combustion aid is the water-based combustion aid prepared in Example 1, and the addition amount is 0.1 wt%) The specific operation steps are as follows: 1) Crushing: Prepare a certain amount and a certain particle size (about 1 mm) of coal gangue samples according to the sample preparation standard requirements; 2) Weighing: Weigh 105 g of coal gangue samples and 0.105 g of the water-based combustion aid in Example 1 using an analytical balance, and put them into crucibles respectively; 3) Stirring: Stir the samples in the crucible for about 5 minutes to make the coal gangue samples and the water-based combustion aid fully mixed, then put them into a sample bag and label. 4) Sample preparation: crush the above sample into a particle size of 100 - 200 mesh required for thermogravimetric combustion. 5) Sampling: dry the sample in step 4 and measure it using a thermogravimetric analyzer. Weigh 5 mg of the dried sample for each test, and use the dried coal gangue sample without any combustion aids as a control.

[0052] Among them, a thermogravimetric analyzer produced by Netzsch of Germany is used for thermogravimetric combustion testing. The conditions for thermogravimetric combustion testing are as follows: under air conditions, the air flow rate is 50 mL / min, the temperature is programmed to rise from room temperature to 1000 °C at a heating rate of 10 °C / min. Synchronously record the TG (thermogravimetric) and DTG (differential thermogravimetric) curves, and analyze the combustion characteristic parameters (ignition temperature, burnout temperature, maximum weight loss rate, etc.). The results are as Figure 3 and Figure 4 shown.

[0053] Figure 3 The solid line in Figure 3 is the TG curve of the coal gangue sample,

[0054] Figure 4 The solid line in Figure 4 is the TG curve of the sample of coal gangue added with the aqueous combustion aid in Example 1,

[0055] From Figure 3 the comparison and analysis of the TG curves of the coal gangue sample in Figure 4 and the TG curve of the sample of coal gangue added with the aqueous combustion aid in Example 1 in

[0056] From Figure 3 the DTG curve of the coal gangue sample in Figure 4From the comparative analysis of the DTG curves of the sample of coal gangue added with the water-based combustion aid in Example 1, it can be seen that as the temperature continuously rises, the weight loss rate of the sample also changes continuously. Two decomposition peaks appear throughout the process. The two decomposition peaks of the coal gangue sample are at 113.04 °C and 525.72 °C respectively. The two decomposition peaks of the coal gangue sample added with the water-based combustion aid are at 118.72 °C and 530.77 °C respectively. Analyzing the reasons, the appearance of the first decomposition peak is due to the increase in the weight loss rate caused by the evaporation of a small amount of water contained in the coal gangue during the initial temperature rise; when the temperature reaches 500 °C, the curve of the coal gangue sample starts to decline, and the second splitting peak appears, reaching the lowest point at about 525.72 °C, and then starts to rise. After 600 °C, the curve flattens out, and the weight loss rate per minute is 2.227% / min. For the coal gangue sample added with the water-based combustion aid, it reaches the lowest point at about 530.77 °C, and then starts to rise. After 600 °C, the curve flattens out, and the weight loss rate per minute is 2.193% / min. This proves that the sample added with the combustion aid burns more fully and can better improve the combustion efficiency of coal.

[0057] (3)Testing of coal gangue samples and coal gangue samples added with combustion aid (the coal gangue used has a calorific value of 2000 kcal / kg, and the water-based combustion aid prepared in Example 3 of the combustion aid is used, with an addition amount of 0.1 wt%) The specific operation steps are as follows: 1) Crushing: Prepare a certain amount and a certain particle size (about 1 mm) of coal combustion sample according to the sample preparation standard requirements; 2) Weighing: Weigh 105 g of coal gangue sample and 0.105 g of the water-based combustion aid in Example 3 by an analytical balance, and put them into crucibles respectively; 3) Stirring: Stir the sample in the crucible for about 5 minutes to make the coal gangue sample and the water-based combustion aid fully mixed, and then put them into a sample bag and label; 4) Sample preparation: Crush the above sample into a particle size of 100 mesh to 200 mesh required for thermogravimetric combustion; 5) Sampling: Dry the sample in step 4, and measure it by a thermogravimetric analyzer. Weigh 5 mg of the dried sample each time for testing, and use the dried coal gangue sample without adding any combustion aid as a control.

[0058] Among them, a thermogravimetric combustion test is carried out using a thermogravimetric analyzer produced by Netzsch Company of Germany. The conditions for the thermogravimetric combustion test are as follows: under air conditions, the air flow rate is 50 mL / min, the temperature is programmed to rise from room temperature to 800 °C, and the heating rate is 10 °C / min. Synchronously record the TG (thermogravimetry) and DTG (differential thermogravimetry) curves, and analyze the combustion characteristic parameters (ignition temperature, burnout temperature, maximum weight loss rate, etc.). The results are as Figure 5 and Figure 6as shown

[0059] Figure 5 The solid line in it is the TG curve of the coal gangue sample, Figure 5 and the dashed line in it is the DTG curve of the coal gangue sample.

[0060] Figure 6 The solid line in it is the TG curve of the sample of coal gangue added with the water-based combustion aid in Example 3, Figure 6 and the dashed line in it is the DTG curve of the sample of coal gangue added with the water-based combustion aid in Example 3.

[0061] From Figure 5 the TG curve of the coal gangue sample in it and Figure 6 the TG curve of the sample of coal gangue added with the water-based combustion aid in Example 3 in it, by comparative analysis, it can be seen that the initial temperature is 35°C. During the whole experiment, the stages with obvious changes in the weight loss of the two samples are concentrated in the temperature range of 300 - 600°C. The reason should be that the volatilization point or ignition point of the available substances in the sample within 1000°C is in this temperature range, so there will be a large change in weight. When the temperature of the coal gangue reaches 317.67°C, the curve drops rapidly. When the temperature of the sample added with the water-based combustion aid reaches 280.85°C, the curve drops rapidly. The test results show that adding the water-based combustion aid can reduce the ignition point of the coal gangue by 37°C. Among them, the remaining of the coal gangue sample at 115.80°C is 96.155%, indicating that in the initial weight loss stage, due to the precipitation of adsorbed water or volatile components. The remaining of the sample at 458.47°C is 93.262%, indicating that in the main decomposition stage, it corresponds to the thermal decomposition of organic matter or minerals in the coal gangue. While the sample of coal gangue added with the water-based combustion aid in Example 3 has three obvious thermal decomposition stages. The remaining of the sample at 121.30°C is 98.655%, indicating that in the initial weight loss stage, due to the precipitation of adsorbed water or volatile components. The remaining of the sample at 220.90°C is 97.381%, indicating that it is a new stage, and the combustion aid catalyzes the low-temperature decomposition reaction (such as the premature oxidation of organic components). The remaining of the sample at 444.82°C is 89.484%, indicating that the temperature of the main decomposition stage decreases, indicating that the combustion aid promotes the high-temperature decomposition or combustion reaction. It is proved that after adding the water-based combustion aid, the weight loss rate in the main decomposition stage is reduced from 2.134% to 1.572%, indicating that the addition of the water-based combustion aid prolongs the combustion time.

[0062] From Figure 5 the DTG curve of the coal gangue sample in it and Figure 6From the comparative analysis of the DTG curves of the sample of coal gangue added with the water-based combustion promoter in Example 3, it can be seen that the addition of the water-based combustion promoter effectively reduces the ignition point of the coal gangue sample from 317 °C to 280 °C, significantly improving the initial combustion conditions; by catalyzing the low-temperature oxidation reaction (220.90 °C) and reducing the main decomposition temperature (458.47 °C → 444.82 °C), the thermal decomposition path of coal gangue is significantly optimized. The catalytic reaction in the low-temperature zone broadens the combustion window and extends the combustion time, while the reduction of the main decomposition temperature in the high-temperature zone reduces the heat energy dissipation; through the catalytic effect, the combustion of combustibles in coal gangue is fully stimulated, the combustion process is extended, and the utilization rate of combustibles in coal gangue is increased. Through comprehensive analysis, the water-based combustion promoter effectively optimizes the combustion performance of coal gangue by optimizing the thermal decomposition path, which is of great significance for improving energy utilization efficiency and reducing environmental pollution.

[0063] In summary, the water-based combustion promoter of the present invention uses plant polyphenol-modified nanocellulose and metal salts as raw materials, and its components do not contain explosive substances, ensuring the use safety. The combustion promoter is water-based, which is convenient for use. Moreover, as a combustion promoter, it has a small dosage, effectively reduces the cost, and reduces the emission of pollutants.

[0064] The water-based combustion promoter of the present invention is used as a combustion promoter in coal gangue, which can significantly reduce the ignition point of coal gangue, accelerate the combustion speed of combustible substances, reduce the amount of residues after combustion, extend the combustion time, make the combustion more complete, improve the combustion efficiency, and is easy to operate. It can be mixed with water in proportion during the coal washing process and directly sprayed on coal for combustion or coal gangue. Therefore, it can not only improve the utilization efficiency of coal gangue, reduce environmental pollution, and lower the coal combustion cost, but also is expected to bring a revolutionary change to the coal industry, achieving a win-win situation of economic benefits and environmental protection. It has great popularization and application value in the field of combustion promoter technology.

[0065] The above embodiments are only preferred embodiments given to fully illustrate the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or transformations made by those skilled in the art on the basis of the present invention are all within the protection scope of the present invention.

Claims

1. A water-based combustion improver, characterized in that: Includes plant polyphenols, nanocellulose and metal salts.

2. The aqueous combustion improver according to claim 1, characterized in that It includes nanocellulose modified with plant polyphenols, metal salts and solvents; The metal salts include iron salts, copper salts, calcium salts and sodium salts.

3. The aqueous combustion improver according to claim 2, characterized in that: The iron salt is selected from at least one of ferric chloride, ferric nitrate, ferric sulfate, ferric phosphate, ferrocene, ferrous chloride, ferrous nitrate and ferrous sulfate; And / or, the copper salt is selected from at least one of copper sulfate, copper nitrate, copper chloride, copper acetate and copper carbonate; And / or, the calcium salt is selected from at least one of calcium chloride, calcium oxide, calcium hydroxide, calcium phosphate, calcium acetate and calcium citrate; And / or, the sodium salt is selected from at least one of sodium chloride, sodium humate, sodium formate, sodium sulfate, disodium hydrogen phosphate and sodium citrate.

4. The aqueous combustion improver according to claim 1, characterized in that: The plant polyphenols are selected from at least one of tea polyphenols, gallic acid, catechol, ellagic acid, catechin, tannic acid, larch tannin, bayberry tannin, black wattle tannin and persimmon tannin.

5. A method for preparing an aqueous combustion improver according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1, dissolving plant polyphenols in a solvent, then adding nanocellulose, heating to a preset temperature, adding a high molecular polymer, continuing heating and stirring to obtain a suspension, i.e., a nanocellulose solution modified with plant polyphenols; S2. Add metal salt to the suspension to obtain an aqueous combustion improver.

6. The method for preparing the aqueous combustion improver according to claim 5, characterized in that: The preset temperature is 25~60℃.

7. The method for preparing the aqueous combustion improver according to claim 5, characterized in that: The high molecular polymer is selected from PEG200 (polyethylene glycol 200), PEG400 (polyethylene glycol 400), PEG600 (polyethylene glycol 600), PEG1000 (polyethylene glycol 1000), PEG20000 (polyethylene glycol 20000), PVA1788 (polyvinyl alcohol 1788), PVA2488 (polyvinyl alcohol 2488), PAM-3M (polyacrylamide-3M), PAM-8M (polyacrylamide-8M), PVP At least one of K30 (polyvinyl pyrrolidone K30), PVPK90 (polyvinyl pyrrolidone K90), CMC-Na-220 (sodium carboxymethyl cellulose 220), CMC-Na-450 (sodium carboxymethyl cellulose 450), PEO-100K (polyethylene oxide 100K), PEO-300K (polyethylene oxide 300K), PAAS-5000 (sodium polyacrylate 5000), PAAS-10000 (sodium polyacrylate 10000) and mPEG2000 (polyethylene glycol monomethyl ether 2000); And / or, the solvent is selected from at least one of water, ethanol and ethylene glycol.

8. The method for preparing the aqueous combustion improver according to claim 5, characterized in that: In the suspension, the mass percentage of plant polyphenols is 5-15%, the mass percentage of nanocellulose is 3-10%, and the mass percentage of high molecular polymer is 30-60%; And / or, the metal salt includes iron salt, copper salt, calcium salt and sodium salt, and the suspension, iron salt, copper salt, calcium salt and sodium salt are 10-30 parts, 5-20 parts, 5-15 parts, 3-10 parts and 5-15 parts by weight; And / or, S2 comprises: adding a metal salt to the suspension, adjusting the viscosity to (20±3) mPa·s with water, and obtaining an aqueous combustion improver.

9. A use of the aqueous combustion improver according to any one of claims 1 to 4, characterized in that: The aqueous combustion improver is used as a coal gangue combustion improver.

10. The use according to claim 9, characterized in that: When the aqueous combustion-supporting agent is used as a coal gangue combustion-supporting agent, no oxidant needs to be added; And / or, the amount of the aqueous combustion aid added as a coal gangue combustion aid is ≤1%.

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