Glass transition materials for circulating fluidized beds and methods of making and using the same

Abstract

The present invention relates to a glass transition material for a circulating fluidized bed (CFB) and its preparation and use methods, belonging to the technical field of comprehensive utilization of CFB fly ash. The glass transition material is prepared from 85-100 parts by weight of manganese monoxide, 5-30 parts by weight of niobium nitride, 5-15 parts by weight of polyoxyethylene lauryl ether, and 15-40 parts by weight of water. During preparation, polyoxyethylene lauryl ether and water are first mixed, followed by the addition of manganese monoxide and niobium nitride, and vigorous stirring in a blender. The present invention utilizes polyoxyethylene lauryl ether to uniformly disperse manganese monoxide and niobium nitride in a coal sample. The mineralization effect of manganese monoxide and niobium nitride reduces the liquid phase formation temperature and liquid phase viscosity, increases the liquid phase ratio, and promotes the glass transition of CFB fly ash. Furthermore, nitrogen generated by the high temperature of niobium nitride creates pores, increasing the content of hollow microspheres in the CFB fly ash.

Description

Technical Field

[0001] The present invention belongs to the technical field of comprehensive utilization of circulating fluidized bed fly ash, and particularly relates to a technology for improving the activity of circulating fluidized bed fly ash, specifically a glass transition material for a circulating fluidized bed and a preparation and use method thereof. Background Art

[0002] Circulating fluidized bed (CFB) combustion technology is a new, recently developed clean coal combustion technology. Due to its low combustion temperature (800-900°C), it produces low nitrogen oxide emissions. Its wide fuel compatibility and high combustion efficiency have led to its rapid adoption and adoption in domestic power plants. However, due to the low combustion temperature of CFB boilers, the carbon content of CFB fly ash is high (around 7%), resulting in low pozzolanic activity. Furthermore, the low combustion temperature hinders the formation of hollow microspheres within the CFB fly ash, resulting in high water requirements and severe cracking in the concrete. This restricts the direct use of CFB fly ash in building materials such as cement and concrete. Large amounts of CFB fly ash accumulate, occupying significant amounts of arable land and polluting the environment.

[0003] Existing utilization of circulating fluidized bed (CFB) fly ash primarily relies on post-activation to enhance its reactivity. This involves using strong acids and bases to disrupt the stable mineral components and inclusions within the CFB fly ash, dissolving the active SiO2 and Al2O3, and increasing its reactivity. Common activators include strong acids such as H2SO4, HCl, and HF, and strong bases such as sodium hydroxide, potassium hydroxide, and sodium carbonate. While acid-base activation techniques can enhance CFB fly ash reactivity, they do not address its high water requirement, resulting in limitations on the amount of CFB fly ash that can be incorporated into the CFB. Summary of the Invention

[0004] The purpose of the present invention is to solve the problems of low vitrification degree and large water requirement of fly ash in a circulating fluidized bed, and to provide a glass transition material for a circulating fluidized bed.

[0005] The present invention is achieved through the following technical solutions:

[0006] A glass transition material for a circulating fluidized bed is prepared from the following raw materials in parts by weight: 85-100 parts of manganese monoxide, 5-30 parts of niobium nitride, 5-15 parts of polyoxyethylene lauryl ether, and 15-40 parts of water.

[0007] Preferably, the particle size of manganese monoxide is 100-200 mesh, and the particle size of niobium nitride is 200-400 mesh.

[0008] Furthermore, the present invention also provides a method for preparing the glass transition material for a circulating fluidized bed, comprising the following steps:

[0009] 1) Heat water to 40°C, then add polyoxyethylene lauryl ether into the water, mix, and mechanically stir for 30 minutes to obtain an emulsion;

[0010] 2) Slowly add manganese monoxide and niobium nitride to the emulsion, maintain the water temperature at 40°C, and stir at high speed for 30 minutes at a speed of 5000 r / min. Finally, the glass transition material is obtained, which can be sealed and stored.

[0011] Furthermore, the present invention also provides a method for using the glass transition material for a circulating fluidized bed, comprising the following steps:

[0012] 1) Fully mixing the glass transition material and pulverized coal in a mixer to obtain a mixture;

[0013] 2) The obtained mixture is made into coal particles through a granulator and a dryer, and then sent into a circulating fluidized bed boiler for combustion.

[0014] Preferably, in step 1), the weight ratio of the glass transition material to the coal powder is 1:500.

[0015] The technical principle of this invention is to use polyoxyethylene lauryl ether to uniformly disperse manganese monoxide and niobium nitride in a coal sample. The mineralization effect of manganese monoxide and niobium nitride reduces the liquid phase formation temperature and liquid phase viscosity, increases the liquid phase ratio, and promotes the glass transition of the circulating fluidized bed fly ash. Simultaneously, the nitrogen generated by the high temperature of niobium nitride creates pores, increasing the content of hollow microspheres in the circulating fluidized bed fly ash. Unlike traditional technologies, this invention directly addresses the formation process of the circulating fluidized bed fly ash, using materials that promote glass transition to increase the content of glassy substances in the circulating fluidized bed fly ash. This significantly reduces the water requirement of the circulating fluidized bed fly ash and increases the amount of circulating fluidized bed fly ash added.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1) The glass transition material of the present invention can increase the glass transition rate of circulating fluidized bed fly ash. The mineralization effect of manganese monoxide and niobium nitride in a specific ratio can reduce the liquid phase formation temperature and liquid phase viscosity, increase the liquid phase ratio, and thus increase the glass bead content in the circulating fluidized bed fly ash after cooling, thereby reducing the porosity of the circulating fluidized bed fly ash, significantly reducing its water requirement, and increasing its mixing amount in cement concrete products.

[0018] 2) The present invention utilizes nitrogen generated by high temperature niobium nitride to form pores, thereby increasing the content of hollow microspheres in the circulating fluidized bed fly ash.

[0019] 3) The present invention utilizes the grinding aid and dispersing effect of polyoxyethylene lauryl ether to improve the uniformity of dispersion of manganese monoxide and niobium nitride in the coal sample and improve the glass transition efficiency of manganese monoxide and niobium nitride on the coal sample.

[0020] 4) The present invention can significantly reduce the water demand of circulating fluidized bed fly ash, improve the density of concrete products, and thus improve the strength and freeze-thaw resistance of concrete. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a comparison diagram of the glass transition of circulating fluidized bed fly ash.

[0022] Figure 2 This is the X-ray diffraction pattern of fly ash from a circulating fluidized bed. DETAILED DESCRIPTION

[0023] The present invention will be further described below with reference to specific embodiments: Example 1

[0024] A glass transition material for a circulating fluidized bed is prepared from the following raw materials in parts by weight: 100g manganese monoxide, 5g niobium nitride, 5g polyoxyethylene lauryl ether, and 15g water; wherein the particle size of the manganese monoxide is 100 mesh, and the particle size of the niobium nitride is 200 mesh.

[0025] The method for preparing the glass transition material for a circulating fluidized bed comprises the following steps:

[0026] 1) Heat 15 g of water to 40°C, then add 5 g of polyoxyethylene lauryl ether to the water, mix, and mechanically stir for 30 minutes to obtain an emulsion;

[0027] 2) Slowly add 100 g of manganese monoxide and 5 g of niobium nitride to the emulsion, maintain the water temperature at 40° C., and stir at a high speed of 5000 rpm for 30 minutes to obtain the glass transition material, which is then sealed and stored.

[0028] The method for using the glass transition material for a circulating fluidized bed comprises the following steps:

[0029] 1) 10 g of glass transition material and 5 kg of coal powder were thoroughly mixed in a blender for 15 minutes to obtain a mixture;

[0030] 2) The obtained mixture is made into coal particles by a granulator and a dryer, and then fed into a circulating fluidized bed boiler with a combustion temperature of 850°C and a combustion time of 5 seconds. Example 2

[0031] A glass transition material for a circulating fluidized bed is prepared from the following raw materials in parts by weight: 90g of manganese monoxide, 30g of niobium nitride, 15g of polyoxyethylene lauryl ether, and 40g of water; wherein the particle size of the manganese monoxide is 200 mesh, and the particle size of the niobium nitride is 400 mesh.

[0032] The method for preparing the glass transition material for a circulating fluidized bed comprises the following steps:

[0033] 1) Heat 40 g of water to 40°C, then add 15 g of polyoxyethylene lauryl ether to the water, mix, and mechanically stir for 30 minutes to obtain an emulsion;

[0034] 2) Slowly add 90 g of manganese monoxide and 30 g of niobium nitride to the emulsion, maintain the water temperature at 40° C., and stir at high speed for 30 minutes at a speed of 5000 r / min to obtain the glass transition material, which is then sealed and stored.

[0035] The method for using the glass transition material for a circulating fluidized bed comprises the following steps:

[0036] 1) 10 g of glass transition material and 5 kg of coal powder were thoroughly mixed in a blender for 15 minutes to obtain a mixture;

[0037] 2) The obtained mixture is made into coal particles by a granulator and a dryer, and then fed into a circulating fluidized bed boiler with a combustion temperature of 850°C and a combustion time of 5 seconds. Example 3

[0038] A glass transition material for a circulating fluidized bed is prepared from the following raw materials in parts by weight: 95g of manganese monoxide, 15g of niobium nitride, 10g of polyoxyethylene lauryl ether, and 25g of water; wherein the particle size of the manganese monoxide is 150 mesh, and the particle size of the niobium nitride is 300 mesh.

[0039] The method for preparing the glass transition material for a circulating fluidized bed comprises the following steps:

[0040] 1) Heat 25 g of water to 40°C, then add 10 g of polyoxyethylene lauryl ether to the water, mix, and mechanically stir for 30 minutes to obtain an emulsion;

[0041] 2) Slowly add 95 g of manganese monoxide and 15 g of niobium nitride to the emulsion, maintain the water temperature at 40° C., and stir at high speed for 30 minutes at a speed of 5000 r / min to obtain the glass transition material, which is then sealed and stored.

[0042] The method for using the glass transition material for a circulating fluidized bed comprises the following steps:

[0043] 1) 10 g of glass transition material and 5 kg of coal powder were thoroughly mixed in a blender for 15 minutes to obtain a mixture;

[0044] 2) The obtained mixture is made into coal particles by a granulator and a dryer, and then fed into a circulating fluidized bed boiler with a combustion temperature of 850°C and a combustion time of 5 seconds. Example 4

[0045] A glass transition material for a circulating fluidized bed is prepared from the following raw materials in parts by weight: 85g of manganese monoxide, 30g of niobium nitride, 10g of polyoxyethylene lauryl ether, and 30g of water; wherein the particle size of the manganese monoxide is 150 mesh, and the particle size of the niobium nitride is 400 mesh.

[0046] The method for preparing the glass transition material for a circulating fluidized bed comprises the following steps:

[0047] 1) Heat 30 g of water to 40°C, then add 10 g of polyoxyethylene lauryl ether to the water, mix, and mechanically stir for 30 minutes to obtain an emulsion;

[0048] 2) Slowly add 85 g of manganese monoxide and 30 g of niobium nitride to the emulsion, maintain the water temperature at 40° C., and stir at high speed for 30 minutes at a speed of 5000 r / min to obtain the glass transition material, which is then sealed and stored.

[0049] The method for using the glass transition material for a circulating fluidized bed comprises the following steps:

[0050] 1) 10 g of glass transition material and 5 kg of coal powder were thoroughly mixed in a blender for 15 minutes to obtain a mixture;

[0051] 2) The obtained mixture is made into coal particles by a granulator and a dryer, and then fed into a circulating fluidized bed boiler with a combustion temperature of 850°C and a combustion time of 5 seconds. Example 5

[0052] A glass transition material for a circulating fluidized bed is prepared from the following raw materials in parts by weight: 90g of manganese monoxide, 20g of niobium nitride, 10g of polyoxyethylene lauryl ether, and 25g of water; wherein the particle size of the manganese monoxide is 200 mesh, and the particle size of the niobium nitride is 300 mesh.

[0053] The method for preparing the glass transition material for a circulating fluidized bed comprises the following steps:

[0054] 1) Heat 25 g of water to 40°C, then add 10 g of polyoxyethylene lauryl ether to the water, mix, and mechanically stir for 30 minutes to obtain an emulsion;

[0055] 2) Slowly add 90 g of manganese monoxide and 20 g of niobium nitride to the emulsion, maintain the water temperature at 40° C., and stir at high speed for 30 minutes at a speed of 5000 r / min to obtain the glass transition material, which is then sealed and stored.

[0056] The method for using the glass transition material for a circulating fluidized bed comprises the following steps:

[0057] 1) 10 g of glass transition material and 5 kg of coal powder were thoroughly mixed in a blender for 15 minutes to obtain a mixture;

[0058] 2) The obtained mixture is made into coal particles by a granulator and a dryer, and then fed into a circulating fluidized bed boiler with a combustion temperature of 850°C and a combustion time of 5 seconds.

[0059] The above embodiments of the present invention are further described below through specific experimental data:

[0060] The water demand ratio of circulating fluidized bed fly ash is tested according to the test method of the national standard GBT1596-2017 "Fly ash used in cement and concrete".

[0061] In the concrete prepared with circulating fluidized bed fly ash, the circulating fluidized bed replaces cement at a ratio of 30%, and the compressive strength of the concrete is tested according to the test method of the national standard GB╱T 50081-2019 "Standard for Test Methods for Physical and Mechanical Properties of Concrete".

[0062] The relevant experimental results are shown in Table 1:

[0063] Table 1 Circulating fluidized bed fly ash properties

[0064]

[0065] As can be seen from the data in the table above, Examples 2 and 3 exhibit higher total manganese monoxide and niobium nitride usage, and their water requirements are also higher. Overall, the water requirement decreases with increasing total manganese monoxide and niobium nitride usage, demonstrating that manganese monoxide and niobium nitride can effectively reduce the liquidus formation temperature and liquidus viscosity, thereby increasing the glass bead content in circulating fluidized bed fly ash and reducing its water requirement. Comparing Examples 3 and 5, while the total manganese monoxide and niobium nitride usage are identical, Example 3 exhibits a higher manganese monoxide ratio and a lower water requirement, demonstrating that manganese monoxide exhibits superior glass transition properties compared to niobium nitride.

[0066] As can be seen from the data in the table above, the compressive strength test results contradict the water requirement ratio results; that is, the lower the water requirement ratio, the higher the compressive strength. This is because concrete strength is closely related to its internal density. Circulating fluidized bed fly ash, which has a high water requirement, has a low internal vitreous content and a high porosity, requiring more water for concrete mixing. However, most of this water exists as free water during the curing process, leaving behind a large number of capillaries after curing, reducing density and compressive strength.

[0067] Figure 1 Figure 1 shows a comparison of the glass transition behavior of circulating fluidized bed (CFB) fly ash. Figure a shows the CFB fly ash without the addition of a glass transition material. As can be seen, the CFB fly ash is composed of irregularly shaped, loose, and porous slag-like particles. Figure b shows the CFB fly ash with the addition of a glass transition material. As can be seen, the CFB fly ash contains spherical particles of varying sizes. These particles are relatively regular in shape and have a dense surface. This is primarily due to the combustion temperature of the CFB boiler, which is between 850°C and 950°C. This makes the ash difficult to melt, making it difficult to produce spherical microspheres. The addition of a glass transition material can lower the melting temperature of the ash, increasing the liquid phase content in the ash and thus forming a certain amount of spherical microspheres.

[0068] Figure 2 This is the X-ray diffraction pattern of circulating fluidized bed fly ash. It can be seen from the figure that the main crystal phase in the circulating fluidized bed fly ash is SiO2 crystal, and the rest is amorphous non-crystalline phase.

[0069] The above-described embodiments merely illustrate several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, and all such variations and improvements fall within the scope of protection of the present invention.

Claims

1. A glass transition material for a circulating fluidized bed, characterized in that: The invention is prepared from the following raw materials in parts by weight: 85-100 parts of manganese monoxide, 5-30 parts of niobium nitride, 5-15 parts of polyoxyethylene lauryl ether and 15-40 parts of water.

2. The glass transition material for a circulating fluidized bed according to claim 1, characterized in that: The particle size of manganese monoxide is 100-200 meshes, and the particle size of niobium nitride is 200-400 meshes.

3. The method for preparing a glass transition material for a circulating fluidized bed according to claim 1 or 2, wherein: The steps include: 1) Heat water to 40°C, then add polyoxyethylene lauryl ether into the water, mix, and mechanically stir for 30 minutes to obtain an emulsion; 2) Slowly add manganese monoxide and niobium nitride to the emulsion, maintain the water temperature at 40°C, and stir at high speed for 30 minutes at a speed of 5000 r / min. Finally, the glass transition material is obtained, which can be sealed and stored.

4. The method for using a glass transition material for a circulating fluidized bed according to claim 1 or 2, wherein: The steps include: 1) Fully mixing the glass transition material and pulverized coal in a mixer to obtain a mixture; 2) The obtained mixture is made into coal particles through a granulator and a dryer, and then sent into a circulating fluidized bed boiler for combustion.

5. The method for using a glass transition material for a circulating fluidized bed according to claim 4, wherein: In step 1), the weight ratio of the glass transition material to the coal powder is 1:500.

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