Preparation method of biomass briquette of low-calorific-value coal

Abstract

The invention discloses a preparation method of biomass briquette of low-calorific-value coal, and relates to the technical field of coal processing and conversion, and the preparation method comprises the following steps: step 1, crushing the low-calorific-value coal until the particle size d1 is greater than or equal to 0.5 mm and less than or equal to 2mm; 2, selecting a biomass raw material, crushing the biomass raw material until the particle size is d2, and proportioning according to the mass ratio of m1: m2 (low-calorific-value coal to the biomass raw material); the preparation method comprises the following steps: crushing low-calorific-value coal to 0.5-2mm, crushing a biomass raw material to 0.2-1mm, mixing according to a mass ratio of 3: 1-5: 1, adding a binder accounting for 3-8% of the mass of the total raw material, stirring at a rotating speed of 100-200r / min for 15-30min to make the raw material uniform, molding at a pressure of 5-10MPa by using a mold with a specific size, and curing at 100-120 DEG C for 2-4h after molding, thereby obtaining the low-calorific-value coal-biomass composite material. The obtained biomass briquette not only promotes heat release and transfer during combustion due to reasonable particle size and proportion and improves energy utilization efficiency, but also reduces emission of pollutants such as dust and sulfur dioxide due to addition of biomass and control of water content of low-calorific-value coal.

Description

Technical Field

[0001] The present invention relates to the technical field of coal processing and conversion, and specifically to a preparation method of biomass briquettes from low calorific value coal. Background Art

[0002] With the continuous growth of energy demand and the increasingly strict environmental protection requirements, the efficient and clean utilization of coal resources has become a research hotspot. As a coal resource with rich reserves but relatively low calorific value, the direct combustion of low calorific value coal not only has low energy utilization efficiency, but also produces a large amount of pollutants such as dust and sulfur dioxide, causing great pressure on the environment. The traditional treatment methods for low calorific value coal are mostly simple stacking or inefficient combustion, which not only wastes resources but also causes environmental pollution problems.

[0003] As a new type of fuel, biomass briquettes can improve the combustion performance of coal and enhance the energy utilization efficiency by combining biomass with coal. However, there are many problems in the current preparation methods of biomass briquettes. For example, the selection and treatment of raw materials are not scientific enough, resulting in poor briquette forming effect and low strength, and being easily broken during transportation and storage; the use of binders is unreasonable, affecting the combustion characteristics and environmental protection performance of briquettes; the preparation process parameters lack optimization, resulting in low production efficiency and high costs. Therefore, it is of great practical significance to develop a scientific, reasonable, efficient and environmentally friendly preparation method for biomass briquettes from low calorific value coal. Summary of the Invention

[0004] To solve the above technical problems and provide a preparation method of biomass briquettes from low calorific value coal, the present technical solution solves the above problems.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A preparation method of biomass briquettes from low calorific value coal, comprising the following steps:

[0007] Step 1: Crush the low calorific value coal to a particle size of d1, where 0.5 mm ≤ d1 ≤ 2 mm;

[0008] Step 2: Select biomass raw materials, crush them to a particle size of d2, 0.2 mm ≤ d2 ≤ 1 mm, and mix them according to the mass ratio m1:m2 (low calorific value coal:biomass raw materials), 3:1 ≤ m1:m2 ≤ 5:2;

[0009] Step 3: Add a binder to the proportioned raw materials, and the addition amount of the binder is w% of the total raw material mass, 3% ≤ w ≤ 8%, and mix evenly;

[0010] Step 4: Mould the mixed materials under pressure P, where 5 MPa ≤ P ≤ 10 MPa for the preparation method of biomass briquettes of low calorific value coal, to obtain biomass briquettes.

[0011] Preferably, the calorific value Q of the low calorific value coal satisfies 10 MJ / kg ≤ Q ≤ 15 MJ / kg.

[0012] Preferably, the biomass raw material is one or a combination of straw, wood chips, and rice husks.

[0013] Preferably, the binder is a starch-based binder, and its preparation method is as follows: Mix starch and water at a mass ratio of m3:m4, where 1:5 ≤ M3:M4 ≤ 1:8, stir at temperature T1 for t1 time, where 80°C ≤ T1 ≤ 95°C and 30 min ≤ t1 ≤ 60 min, to obtain the starch-based binder.

[0014] Preferably, in Step 3, the mixing is carried out by stirring, the stirring speed n is 100 r / min ≤ n ≤ 200 r / min, and the stirring time t2 is 15 min ≤ t2 ≤ 30 min.

[0015] Preferably, in Step 4, the moulding is carried out using a mould. The shape of the mould is a cuboid, and its length L, width W, and height H satisfy 5 cm ≤ L ≤ 10 cm, 3 cm ≤ W ≤ 6 cm, and 2 cm ≤ H ≤ 4 cm.

[0016] Preferably, before Step 1, the low calorific value coal is dried to reduce its water content c to 3% ≤ C ≤ 6%.

[0017] Preferably, after Step 4, the formed biomass briquettes are cured. The curing temperature T2 is 100°C ≤ T2 ≤ 120°C, and the curing time t3 is 2 h ≤ t3 ≤ 4 h.

[0018] Preferably, the compressive strength S of the biomass briquettes satisfies 1000 N ≤ S ≤ 1500 N.

[0019] Preferably, in Step 2, the equipment used for crushing the biomass raw material is a hammer mill, and the number of hammer pieces N is 20 ≤ N ≤ 30.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: By crushing low-calorie coal to 0.5 mm - 2 mm, pulverizing biomass raw materials to 0.2 mm - 1 mm and mixing them in a mass ratio of 3:1 to 5:1, adding a binder accounting for 3% - 8% of the total raw material mass, stirring at a speed of 100 r / min - 200 r / min for 15 min - 30 min to make it uniform, then molding under a pressure of 5 MPa - 10 MPa using a specific-size mold, and curing at 100 °C - 120 °C for 2 h - 4 h after molding, the obtained biomass briquette not only promotes heat release and transfer during combustion and improves energy utilization efficiency due to reasonable particle sizes and ratios, but also reduces emissions of pollutants such as dust and sulfur dioxide due to the addition of biomass and the control of the water content of low-calorie coal; at the same time, the specific binder and molding process endow the briquette with a compressive strength of 1000 N - 1500 N, ensuring quality stability; common raw material equipment and optimized process parameters reduce energy and raw material waste, lower production costs, realize the resource recycling of low-calorie coal and biomass waste, create double economic and environmental benefits, and find a new utilization way for biomass waste, creating double economic and environmental benefits. Specific Embodiments

[0021] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments in the following description are only examples, and those skilled in the art can think of other obvious variations.

[0022] A preparation method of a biomass briquette from low-calorie coal includes the following steps:

[0023] Step 1: Crush low-calorie coal to a particle size of d1, where 0.5 mm ≤ d1 ≤ 2 mm;

[0024] Step 2: Select biomass raw materials, pulverize them to a particle size of d2, 0.2 mm ≤ d2 ≤ 1 mm, and perform the ratio according to the mass ratio m1:m2 (low-calorie coal: biomass raw materials), 3:1 ≤ m1:m2 ≤ 5:2;

[0025] Step 3: Add a binder to the proportioned raw materials, and the addition amount of the binder is w% of the total raw material mass, 3% ≤ w ≤ 8%, and mix evenly;

[0026] Step 4: Mold the mixed material under a pressure of P, 5 MPa ≤ P ≤ 10 MPa, to obtain a biomass briquette.

[0027] The calorific value Q of the low-calorie coal satisfies 10 MJ / kg ≤ Q ≤ 15 MJ / kg.

[0028] The biomass raw materials are one or a combination of straw, wood chips, and rice husks.

[0029] The binder is a starch-based binder, and its preparation method is as follows: Starch and water are mixed at a mass ratio of m3:m4, where 1:5 ≤ M3:M4 ≤ 1:8. Stir for a time t1 at a temperature T1, where 80°C ≤ T1 ≤ 95°C and 30 min ≤ t1 ≤ 60 min, to obtain the starch-based binder.

[0030] In the third step, stirring is used for mixing, the stirring speed n is 100 r / min ≤ n ≤ 200 r / min, and the stirring time t2 is 15 min ≤ t2 ≤ 30 min.

[0031] In the fourth step, molding is carried out using a mold. The shape of the mold is a cuboid, and its length L, width W, and height H satisfy 5 cm ≤ L ≤ 10 cm, 3 cm ≤ W ≤ 6 cm, and 2 cm ≤ H ≤ 4 cm.

[0032] Before the first step, the low-calorie coal is dried to reduce its water content c to 3% ≤ C ≤ 6%.

[0033] After the fourth step, the formed biomass briquette is solidified. The solidification temperature T2 is 100°C ≤ T2 ≤ 120°C, and the solidification time t3 is 2 h ≤ t3 ≤ 4 h.

[0034] The compressive strength S of the biomass briquette satisfies 1000 N ≤ S ≤ 1500 N.

[0035] In the second step, the equipment used for crushing the biomass raw material is a hammer mill, and the number of its hammer pieces N is 20 ≤ N ≤ 30.

[0036] Example 1

[0037] Specific steps:

[0038] Drying treatment: Select low-calorie coal with a calorific value Q = 12 MJ / kg and carry out drying treatment to make its water content C = 4%;

[0039] Crushing: Crush the dried low-calorie coal to a particle size d1 = 1 mm;

[0040] Biomass raw material treatment: Select straw as the biomass raw material and use a hammer mill with the number of hammer pieces N = 25 to crush it to a particle size d2 = 0.5 mm. Mix according to a mass ratio of m1:m2 = 4:1 (low-calorie coal: biomass raw material);

[0041] Binder preparation: Mix starch and water at a mass ratio of m3:m4 = 1:6, stir at a temperature T1 = 85°C for a time t1 = 40 min to obtain the starch-based binder. The addition amount of the binder is w = 5% of the total raw material mass;

[0042] Mixing: Adopt the stirring method, with a stirring speed of n = 150 r / min and a stirring time of t2 = 20 min.

[0043] Forming: Press the mixed material under a pressure of P = 7 MPa using a cuboid mold with a length of L = 7 cm, a width of W = 4 cm, and a height of H = 3 cm for forming;

[0044] Curing: Carry out curing treatment on the formed biomass briquette, with a curing temperature of T2 = 110 °C and a curing time of t3 = 3 h;

[0045] Summary: In this example, common straw is selected as the biomass raw material, and the parameters are taken as intermediate values. The forming and curing conditions are moderate. The prepared biomass briquette has a compressive strength of 1200 N, a relatively high energy utilization rate, and a reduction in pollutant emissions.

[0046] Example 2

[0047] Specific steps:

[0048] Drying treatment: Select low-calorie coal with a calorific value of Q = 10 MJ / kg and dry it to a water content of C = 3%;

[0049] Crushing: Crush the low-calorie coal to a particle size of d1 = 0.5 mm;

[0050] Biomass raw material treatment: Select wood chips as the biomass raw material and crush them to a particle size of d2 = 0.2 mm using a hammer mill with 20 hammer blades. Mix them according to a mass ratio of m1:m2 = 3:1;

[0051] Binder preparation: Mix starch and water according to a mass ratio of m3:m4 = 1:5, stir at T1 = 80 °C for t1 = 60 min to obtain the binder, and the addition amount of the binder is w = 3%.

[0052] Mixing: The stirring speed is n = 100 r / min and the stirring time is t2 = 30 min.

[0053] Forming: Form under a pressure of P = 5 MPa using a mold with a length of L = 5 cm, a width of W = 3 cm, and a height of H = 2 cm.

[0054] Curing: The curing temperature is T2 = 100 °C and the curing time is t3 = 4 h.

[0055] Summary: This example uses low-calorie coal with a relatively low calorific value and water content, and wood chips as the biomass raw material. The parameter settings are on the conservative side, with a relatively low forming pressure and binder dosage. However, after a long curing time, the briquette has a compressive strength of 1050 N and good combustion performance.

[0056] Example 3

[0057] Specific steps:

[0058] Drying treatment: Select low-calorie coal with a calorific value Q = 15 MJ / kg and dry it to a water content C = 6%;

[0059] Crushing: Crush the low-calorie coal to a particle size d1 = 2 mm;

[0060] Biomass raw material treatment: Select rice husks as the biomass raw material and crush them to a particle size d2 = 1 mm using a hammer mill with the number of hammer blades N = 30. Mix them according to the mass ratio m1:m2 = 5:2;

[0061] Binder preparation: Mix starch and water according to the mass ratio m3:m4 = 1:8, stir at T1 = 95 °C for t1 = 30 min to obtain the binder, and the addition amount of the binder w = 8%;

[0062] Mixing: Stirring speed n = 200 r / min, stirring time t2 = 15 min;

[0063] Forming: Under a pressure P = 10 MPa, use a mold with a length L = 10 cm, width W = 6 cm, and height H = 4 cm for forming;

[0064] Curing: Curing temperature T2 = 120 °C, curing time t3 = 2 h;

[0065] Summary: This example uses low-calorie coal with a relatively high calorific value and water content, rice husks as the biomass raw material, with parameter settings being relatively aggressive, a relatively high forming pressure and binder dosage, resulting in the briquette having a compressive strength of 1450 N and stable combustion performance.

[0066] Example 4

[0067] Specific steps:

[0068] Drying treatment: Select low-calorie coal with a calorific value Q = 13 MJ / kg and dry it to a water content C = 5%;

[0069] Crushing: Crush the low-calorie coal to a particle size d1 = 1.5 mm;

[0070] Biomass raw material treatment: Select a mixture of straw and wood chips in a ratio of 1:1 as the biomass raw material and crush them to a particle size d2 = 0.6 mm using a hammer mill with the number of hammer blades N = 22. Mix them according to the mass ratio m1:m2 = 4.5:1;

[0071] Binder preparation: Mix starch and water according to the mass ratio m3:m4 = 1:7, stir at T1 = 90 °C for t1 = 35 min to obtain the binder, and the addition amount of the binder w = 6%;

[0072] Mixing: Stirring speed n = 160 r / min, stirring time t2 = 22 min;

[0073] Forming: Under a pressure P = 8 MPa, use a mold with a length L = 8 cm, a width W = 5 cm, and a height H = 3.5 cm for forming;

[0074] Curing: The curing temperature T2 = 115 °C, and the curing time t3 = 2.5 h;

[0075] Summary: Using a mixed biomass raw material, with various parameters being at an upper-middle level, the compressive strength of the briquette prepared is 1300 N, and the energy utilization rate and environmental protection performance are good.

[0076] Example 5

[0077] Specific steps:

[0078] Drying treatment: Select low-calorie coal with a calorific value Q = 11 MJ / kg and dry it to a water content C = 4.5%;

[0079] Crushing: Crush the low-calorie coal to a particle size d1 = 0.8 mm;

[0080] Biomass raw material treatment: Select straw, wood chips, and rice husks mixed in a ratio of 1:1:1 as the biomass raw material, and crush it to a particle size d2 = 0.4 mm using a hammer mill with the number of hammer pieces N = 28. Mix in a mass ratio of m1:m2 = 3.5:1;

[0081] Binder preparation: Mix starch and water in a mass ratio of m3:m4 = 1:6.5, stir at T1 = 88 °C for t1 = 45 min to obtain the binder, and the addition amount of the binder w = 7%;

[0082] Mixing: The stirring speed n = 180 r / min, and the stirring time t2 = 18 min;

[0083] Forming: Under a pressure P = 9 MPa, use a mold with a length L = 9 cm, a width W = 5.5 cm, and a height H = 3.2 cm for forming;

[0084] Curing: The curing temperature T2 = 112 °C, and the curing time t3 = 3.5 h;

[0085] Summary: Using a mixture of three biomass raw materials, with the parameter settings being relatively precise, the compressive strength of the briquette prepared is 1350 N, and there is a good balance in energy utilization and environmental protection.

[0086] Summary of the summary:

[0087] As can be seen from the above five different embodiments, the preparation method of the biomass briquette from low calorific value coal has strong flexibility and adaptability. The parameters of each step can be adjusted according to different characteristics of low calorific value coal, types of biomass raw materials and performance requirements. While ensuring that the compressive strength of the briquette is within the range of 1000N - 1500N, it can effectively improve the energy utilization rate, reduce pollutant emissions and achieve the comprehensive utilization of resources.

[0088] Test Experiment Design

[0089] Experimental Method:

[0090] The biomass briquettes prepared in the five embodiments are tested for compressive strength, energy utilization rate and pollutant emissions. The compressive strength is tested using a universal material testing machine; the energy utilization rate is calculated by measuring the ratio of the heat released by the combustion of the briquette to the theoretical heat; the pollutant emissions are measured using professional gas detection equipment for the emission concentrations of sulfur dioxide and dust.

[0091]

[0092] Comparative Experiment

[0093] Comparative Experiment 1: Comparison of Different Binders

[0094]

[0095] Comparative Experiment 2: Comparison with or without Biomass Raw Materials

[0096]

[0097] Comparative Experiment 3: Comparison of Different Molding Pressures

[0098]

[0099]

[0100] Through the above comparative experiments, the significant advantages of this technical solution in many aspects can be clearly seen. In terms of binder selection, compared with the traditional bentonite binder, the starch-based binder used in this solution, with a lower dosage, has increased the compressive strength of the briquette from 900N to 1200N, while the energy utilization rate has increased from 80% to 85%, and the sulfur dioxide emission concentration has decreased from 150mg / m 3 to 120mg / m 3 , and the dust emission concentration has decreased from 40mg / m 3 to 30mg / m 3 , greatly improving the performance of the briquette and reducing pollutant emissions.

[0101] In terms of adding biomass raw materials, after adding biomass raw materials, the compressive strength of the briquette increases from 1000 N to 1200 N, the energy utilization rate increases significantly from 75% to 85%, and the sulfur dioxide emission concentration decreases from 200 mg / m 3 to 120 mg / m 3 , and the dust emission concentration decreases from 50 mg / m 3 to 30 mg / m 3 , which strongly proves the key role of biomass raw materials in enhancing the performance of briquettes and improving the environmental protection level.

[0102] In terms of controlling the forming pressure, at a forming pressure of 7 MPa, the compressive strength of the briquette is 1200 N, and there are no obvious defects. The energy utilization rate reaches 85%, and the pollutant emissions are also at a low level. When the forming pressure is too low, at 3 MPa, the compressive strength of the briquette is only 800 N; while when the pressure is too high, at 12 MPa, although the compressive strength can reach 1500 N, cracks appear in the briquette, affecting its quality and stability.

[0103] In summary, through the precise control of the binder selection, biomass raw material addition, and forming pressure, this technical solution comprehensively and systematically improves the performance and environmental protection indicators of briquettes, with outstanding practicality and innovation.

[0104] The preparation method of the biomass briquette of low-calorie coal provided by the present invention has been introduced in detail above. Specific examples are used in this article to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention, including the best mode, and also enables any person skilled in the art to practice the present invention, including manufacturing and using any device or system, and implementing any combination method. It should be noted that for those of ordinary skill in the art in this technical field, several improvements and modifications can be made to the present invention without departing from the principle of the present invention. In particular, as long as there is no structural conflict, the various features in the embodiments disclosed by the present invention can be combined with each other in any way. The exhaustive description of these combinations is not given in this specification only for the sake of saving space and resources. Therefore, the present invention is not limited to the specific embodiments disclosed in the text, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for preparing biomass briquettes of low calorific value coal, characterized in that: The following steps are involved: Step 1: crush the low calorific value coal to a particle size of d1, where 0.5 mm ≤ d1 ≤ 2 mm; Step 2: Select biomass raw materials, crush them to a particle size of d2, 0.2mm≤d2≤1mm, and mix them according to the mass ratio m1:m2 (low calorific value coal: biomass raw materials), 3:1≤m1:m2≤5:2; Step 3: Add a binder to the mixed raw materials, the amount of the binder added is w% of the total raw material mass, 3%≤w≤8%, and mix well; Step 4: Molding the mixed materials under pressure P, 5MP low calorific value coal biomass briquette preparation method ≤ P ≤ 10MP low calorific value coal biomass briquette preparation method to obtain biomass briquette.

2. The method for preparing biomass briquettes of low calorific value coal according to claim 1, characterized in that: The calorific value Q of the low calorific value coal satisfies 10MJ / kg≤Q≤15MJ / kg.

3. The method for preparing biomass briquettes of low calorific value coal according to claim 1, characterized in that: The biomass raw material is one or more combinations of straw, wood chips and rice husk.

4. The method for preparing biomass briquettes of low calorific value coal according to claim 1, characterized in that: The binder is a starch-based binder, and its preparation method is as follows: starch and water are mixed in a mass ratio of m3:m4, 1:5≤M3:M4≤1:8, and stirred at a temperature T1 for a time of t1, 80°C≤T1≤95°C, 30min≤t1≤60min, to obtain a starch-based binder.

5. The method for preparing biomass briquettes of low calorific value coal according to claim 1, characterized in that: In the step three, the mixing is carried out in a stirring manner, the stirring speed n is 100r / min≤n≤200r / min, and the stirring time t2 is 15min≤t2≤30min.

6. The method for preparing biomass briquettes of low calorific value coal according to claim 1, characterized in that: In the step 4, the molding is performed by a mold, and the shape of the mold is a rectangular parallelepiped, and its length L, width W, and height H satisfy 5cm≤L≤10cm, 3cm≤W≤6cm, and 2cm≤H≤4cm.

7. The method for preparing biomass briquettes of low calorific value coal according to claim 1, characterized in that: Before step 1, the low calorific value coal is dried to reduce its moisture content c to 3%≤C≤6%.

8. The method for preparing biomass briquettes of low calorific value coal according to claim 1, characterized in that: After step 4, the formed biomass coal briquettes are solidified, the solidification temperature T2 is 100°C≤T2≤120°C, and the solidification time t3 is 2h≤t3≤4h.

9. The method for preparing biomass briquettes of low calorific value coal according to claim 1, characterized in that: The compressive strength S of the biomass coal briquette satisfies 1000N≤S≤1500N.

10. The method for preparing biomass briquettes of low calorific value coal according to claim 1, characterized in that: In the step 2, the equipment used for crushing the biomass raw material is a hammer mill, and the number of hammers N is 20≤N≤30.

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