Molding additive of biomass pellet fuel and preparation method of molding additive

Abstract

The invention provides a forming additive of biomass pellet fuel and a preparation method of the forming additive. The forming additive comprises the following components in parts by weight: 30-50 parts of an adhesive, 20-40 parts of kaolin, 10-20 parts of a calcium-based additive and 10-20 parts of ammonium phosphate. The prepared forming additive is applied to preparation of biomass pellet fuel, and has high forming rate, crushing resistance, low ash content and high lower calorific value, which indicates that the forming additive is high in utilization rate, good in cohesiveness, strong in binding force, good in combustion performance, low in heat loss and high in economic benefit.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of biomass pellet fuel additives, and particularly relates to a molding additive for biomass pellet fuel and a preparation method thereof. BACKGROUND

[0002] As one of the main forms of biomass energy, biomass pellet fuel can significantly improve the energy density by densifying agricultural and forestry waste (such as sawdust, straw, rice husk, etc.), and is convenient for storage and transportation, which is an effective way to replace fossil fuels. However, due to the influence of factors such as moisture and particle size during the molding process, the molded fuel may not meet the densification requirements, and various pollutants may be released during the combustion process, resulting in problems such as ash accumulation and corrosion in the furnace.

[0003] However, the existing technology mainly uses single-function additives. For example, a large amount of binder is added to improve the molding rate, but the fuel's crushing resistance and mechanical durability are not improved, resulting in a large amount of powder during storage and transportation, and serious loss. Or a large amount of inorganic components are introduced to improve the molding effect, which directly leads to an increase in fuel ash content, dilution of effective energy content, and heavier ash disposal burden after combustion. Single-function additives are difficult to achieve balanced results in reducing molding energy consumption, improving molding rate, maintaining fuel mechanical strength, and improving fuel heat value.

[0004] In view of the defects of the prior art, how to provide a molding additive for biomass pellet fuel with high molding rate, good crushing resistance, low ash content and high low calorific value is a problem to be solved by the present application. SUMMARY

[0005] The present application aims to provide a molding additive for biomass pellet fuel and a preparation method thereof to solve the problems raised in the background art.

[0006] To achieve the above-mentioned purpose, the present application provides a molding additive for biomass pellet fuel and a preparation method thereof, wherein the molding additive comprises the following components by weight: 30-50 parts of a binder, 20-40 parts of kaolin, 10-20 parts of a calcium-based additive, and 10-20 parts of an ammonium phosphate salt.

[0007] As a further improvement, the binder is a phenol-modified sulfonated lignin.

[0008] As a further improvement, the synthesis of the binder comprises the following steps: (1) The sulfonated lignin is first dried, then ball milled and sieved, and the sieved sulfonated lignin, phenol and inorganic alkali solution are added to a flask, heated under reflux with stirring at 60-80℃ in a water bath, and cooled to obtain a mixed solution after the reaction is completed; (2) adding inorganic alkali solution, part of furfural and water into the mixed solution obtained in step (1), stirring and mixing uniformly, then gradually heating to 80-100 DEG C and stirring and reacting, then cooling to 60-80 DEG C, adding part of furfural and inorganic alkali solution, heating to 80-100 DEG C and stirring and reacting, after the reaction, slowly cooling to room temperature, to obtain the binder.

[0009] As a further improvement, the mass ratio of the sieved sulphate lignin to phenol in step (1) is 0.5-2:1.

[0010] As a further improvement, the kaolin has a specification of 500-1500 mesh and a density of 2.54-2.60 g / cm3; the kaolin has an alumina content of 33-37% and a silica content of 55-58%.

[0011] As a further improvement, the mass ratio of the binder to kaolin is 1.1-2:1.

[0012] As a further improvement, the calcium-based additive is at least one of calcium oxide, calcium carbonate, calcium stearate and calcium sorbate.

[0013] In order to inhibit the release of sulfur dioxide in the combustion process of the biomass pellet fuel, preferably, the calcium-based additive is calcium oxide and calcium stearate.

[0014] As a further improvement, the ammonium phosphate salt is at least one of ammonium phosphate, ammonium dihydrogen phosphate and diammonium hydrogen phosphate.

[0015] In order to reduce the generation of molten slag and ash deposition and improve the combustion efficiency, preferably, the ammonium phosphate salt is ammonium dihydrogen phosphate.

[0016] The application also provides a preparation method of the molding additive of the biomass pellet fuel, comprising the following steps: Grinding and sieving the calcium-based additive and the ammonium phosphate salt to a particle size of 100-300 mesh, adding the sieved calcium-based additive and ammonium phosphate salt into a mixer according to the weight fraction, then adding kaolin at room temperature and mixing uniformly, then adding the binder at 30-60 DEG C and continuing to stir and mix uniformly, and finally vacuum dewatering to obtain the molding additive of the biomass pellet fuel.

[0017] As a further improvement, the vacuum degree of the vacuum dewatering is -0.08 to -0.09 MPa, and the dewatering temperature is 60-70 DEG C.

[0018] Compared with the prior art, the application has the following beneficial effects: The present application provides a briquetting additive of biomass pellet fuel and a preparation method thereof. The prepared briquetting additive is applied to the preparation of biomass pellet fuel, has a high briquetting rate, a high anti-crushing property, a low ash content and a high low calorific value, and is high in utilization rate, good in cohesiveness, strong in binding force, good in combustion performance, low in heat loss and high in economic benefit. The phenolic modified kraft lignin as the binder can effectively improve the binding effect of the briquetting additive. A large number of pores are formed through phenolic treatment, the specific surface area is increased, the content of hydroxyl groups of the kraft lignin is effectively increased, the increase of active sites makes it easier to condense with furfural to form an adhesive, and the sintering and ash melting phenomena are improved and the emission of sulfur dioxide is reduced in cooperation with kaolin, calcium-based additive and ammonium phosphate salt, and the combustion is more efficient. DETAILED DESCRIPTION

[0019] The present application will be described below in combination with specific embodiments. It should be noted that the following examples are examples of the present application and are only used to illustrate the present application, but not to limit the present application. Other combinations and various modifications within the concept of the present application can be made without departing from the main idea or scope of the present application.

[0020] In the following examples, the monomers and related reagents used except for binder 1 and binder 2 can be purchased from the market, wherein the kraft lignin is purchased from Hubei Maiduo Biological Technology Co., Ltd., and the model number is MDH; kaolin 1 is purchased from Lingshou County Yuanda Mica Factory, and kaolin 2 is purchased from Lingshou County Ningbo Mineral Products Co., Ltd., and the article number is glt20240329.

[0021] The synthesis of binder 1 comprises the following steps: (1) 50 g of kraft lignin was dried at 80℃ for 36 h, then ball milled for 10 min, and sieved through 120 mesh. 6 g of the sieved kraft lignin, 6 g of phenol and 0.72 g of 40% sodium hydroxide solution were added to a flask, heated under reflux with water bath at 80℃ for 2 h, and then cooled to 60℃ to obtain a mixed solution; (2) 1 g of 40% sodium hydroxide solution, 7 g of furfural and 30 mL of water were added to the mixed solution obtained in step (1), stirred for 10 min to mix uniformly, then gradually heated to 100℃ and stirred for 3 h, then cooled to 70℃, and then 4 g of furfural and 1 g of 40% sodium hydroxide solution were added, heated to 90℃ and stirred for 2 h. After the reaction was completed, the temperature was slowly lowered to room temperature to obtain binder 1, i.e. phenolic modified kraft lignin.

[0022] The synthesis of binder 2 comprises the following steps: 50 g of the sulfite ligin was dried at 80℃ for 36 h, then ball-milled for 10 min, sieved through a 120 mesh sieve, 12 g of the sieved sulfite ligin, 1 g of a 40% by mass sodium hydroxide solution, 6 g of furfural, and 30 mL of water were mixed uniformly by stirring for 10 min, then gradually heated to 100℃ and stirred for 1 h, then cooled to 70℃ and 5 g of furfural and 1 g of a 40% by mass sodium hydroxide solution were added, heated to 90℃ and stirred for 1 h, then cooled to room temperature to obtain the binder 2, which is the un-phenolated modified sulfite ligin binder.

[0023] The preparation method of examples 1-3 and comparative examples 1-3 comprises the following steps: The calcium-based additive and the ammonium phosphate salt were ground and sieved to a particle size of 100 mesh, respectively, and then added to a mixer in a weight ratio, followed by adding kaolin and stirring to mix at room temperature, then adding the binder and stirring to mix at 45℃, and finally vacuum dewatering at -0.09 MPa and 70℃ to obtain a molding additive for biomass pellet fuel.

[0024] The components and contents used in examples 1-3 and comparative examples 1-3 are shown in Table 1 below: Table 1 The pine bark was crushed by a crusher with a 5 mm screen aperture, then sent to an air flow drying chamber to be heated and dried to a moisture content of about 16%, and then the dried pine bark was added to the molding additive prepared in examples 1-3 and comparative examples 1-3 at a mass fraction of 10% in a metering hopper, mixed, and then sent to a ring die briquetting machine by a conveyor, continuously extruded into cylindrical particles with a diameter of 8 mm and a length of 30 mm, to obtain biomass pellet fuel. Molding rate: molding rate (%) = (mass of qualified molded fuel m1 / mass of actual input raw material m0) x 100%; Crushing resistance: 500 g of biomass solid molded fuel M was weighed and put into a bag, the air was excluded, the bag opening was tied tightly, and the bag with the sample was allowed to fall freely to a steel plate or hardened cement floor at a height of 2 m, and the crushing resistance was calculated by continuously falling 5 times, crushing resistance (%) = (mass of biomass pellet solid molded fuel larger than 5 mm / mass of biomass pellet solid molded fuel when put into the bag) x 100%; Ash content: according to NY / T 1881.5-2010; Low calorific value: according to GB / T 30727-2014; The test results are shown in Table 2: Table 2 As can be seen from the test results of Example 1 and Comparative Examples 1-2 in Table 2, compared with the molding additives prepared by using un-phenolated modified lignosulfonate or directly using lignosulfonate as the binder, the molding additives prepared by using phenolated modified lignosulfonate as the binder have higher molding rate and crush resistance when applied in the preparation of biomass pellet fuel, which indicates that the molding additives prepared by the present application have better cohesiveness, can improve the utilization rate of raw materials, enhance the binding force between biomass pellets, and have stronger ability to resist external force impact, and to a certain extent, have lower ash content and higher low calorific value, which indicates that the amount of fuel slagging and ash deposition is smaller, the combustion performance is good, and the economic value is higher. Moreover, as can be seen from the test results of Comparative Example 3, if the specifications, alumina content, and silica content of kaolin (such as kaolin 2) are not within the appropriate range, the performance of the molding additives prepared therefrom will be poorer.

[0025] As can be seen from the test results of Examples 1-3, the molding additives prepared by the preparation method provided by the present application have higher molding rate, crush resistance, lower ash content, and higher low calorific value when applied in the preparation of biomass pellet fuel, which indicates that the utilization rate is high, the cohesiveness is good, the binding force is strong, and the combustion performance is good, the heat loss is low, and the economic benefit is high.

[0026] The above embodiments only serve to illustrate the technical concept and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and implement it, and cannot limit the protection scope of the present application, and any equivalent changes or modifications made according to the spirit and essence of the present application should be covered within the protection scope of the present application.

Claims

1. A briquetting additive for biomass pellet fuel, characterized by, The forming additive comprises the following components by weight: 30-50 parts of a binder, 20-40 parts of kaolin, 10-20 parts of a calcium-based additive, and 10-20 parts of an ammonium phosphate salt.

2. The briquetting additive for biomass pellet fuel according to claim 1, characterized in that, The binder is a phenol-modified kraft lignin.

3. The briquetting additive for biomass pellet fuel according to claim 1, characterized in that, The synthesis of the binder comprises the following steps: (1) The kraft lignin is first dried, then ball-milled and sieved, and the sieved kraft lignin, phenol and inorganic alkali solution are added to a flask, heated in a water bath at 60-80°C, and stirred to reflux, after which the reaction is terminated and the mixture is cooled to obtain a solution; (2) To the solution obtained in step (1), inorganic alkali solution and part of the furfural and water are added, and the mixture is stirred and mixed uniformly, then gradually heated to 80-100°C and stirred to react, after which the temperature is lowered to 60-80°C, and part of the furfural and inorganic alkali solution are added, the temperature is raised to 80-100°C and the reaction is stirred, the reaction is terminated, and the mixture is slowly cooled to room temperature to obtain the binder.

4. The briquetting additive for biomass pellet fuel according to claim 3, characterized in that, In step (1), the sieved kraft lignin and the phenol are added in a mass ratio of 0.5-2:

1.

5. The briquetting additive for biomass pellet fuel according to claim 1, characterized in that, The kaolin has a specification of 500-1500 mesh and a density of 2.54-2.60 g / cm³; the kaolin contains 33-37% of alumina and 55-58% of silica.

6. The briquetting additive for biomass pellet fuel according to claim 1, characterized in that, The binder and the kaolin are added in a mass ratio of 1.1-2:

1.

7. The briquetting additive for biomass pellet fuel according to claim 1, characterized in that, The calcium-based additive is at least one of calcium oxide, calcium carbonate, calcium stearate and calcium sorbate.

8. The briquetting additive for biomass pellet fuel according to claim 1, characterized in that, The ammonium phosphate salt is at least one of ammonium phosphate, ammonium dihydrogen phosphate and diammonium hydrogen phosphate.

9. A method for preparing a forming additive for biomass pellet fuel according to any one of claims 1-8, comprising the following steps: The calcium-based additive and the ammonium phosphate salt are ground and sieved to a particle size of 100-300 mesh, and the sieved calcium-based additive and ammonium phosphate salt are added to a mixer, then kaolin is added and mixed at room temperature, and then the binder is added and mixed at 30-60°C, and finally vacuum dehydration is performed to obtain the forming additive for biomass pellet fuel.

10. The method of claim 9, wherein the biomass pellet fuel molding additive is prepared by mixing the biomass pellet fuel molding additive with water in a ratio of 1 : 1 to 1 :

3. The vacuum degree of the vacuum dehydration is -0.08 to -0.09 MPa, and the dehydration temperature is 60-70°C.

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