CN108439963B - Circulating fluidized bed boiler water-cooled wall castable and preparation method thereof - Google Patents

Abstract

The invention relates to a circulating fluidized bed boiler water-cooled wall castable and a preparation method thereof. The technical scheme is: according to the mass ratio of high alumina bauxite clinker:aluminum sol is 100:(2-5) ingredients, mix, store at room temperature to prepare premix; according to brown corundum fine powder: magnesium aluminum spinel Fine powder: zirconium corundum fine powder: ρ‑alumina fine powder: silicon carbide fine powder The mass ratio is 100:(10～15):(2～5):(5～8):(3～6) Ingredients, Mixing to obtain fine powder; according to the premix: the mass ratio of fine powder is 100: (35-40) ingredients, mixing to obtain a mixture; adding silicon that accounts for 4-5wt% of the mixture to the mixture Sol, stirring, trapping material, namely circulating fluidized bed boiler water wall castable. The process of the invention is simple; the prepared circulating fluidized bed boiler water-cooled wall castable has high strength, good thermal shock stability, high thermal conductivity and good construction performance.

Description

A kind of circulating fluidized bed boiler water wall castable and preparation method thereof

technical field

The invention belongs to the technical field of circulating fluidized bed boiler castables. Specifically, it relates to a circulating fluidized bed boiler water-cooled wall castable and a preparation method thereof.

Background technique

Circulating fluidized bed boiler is a high-efficiency and clean combustion technology that has developed rapidly in the past ten years. It has the characteristics of high combustion rate, good desulfurization effect and high thermal energy utilization rate. However, during the high temperature operation of the circulating fluidized bed boiler, the water-cooled wall refractory materials are also subjected to strong convection erosion and wear of solid fuel, flue gas and dust to varying degrees, which seriously affects the service life of the water-cooled wall refractory materials.

At present, high-aluminum refractory castables are mainly used for circulating fluidized bed boiler water-cooled wall refractories. Although they have good high temperature resistance, high strength and high wear resistance, their main shortcomings are: First, high-alumina refractories resist thermal stress cycles. The ability to act is poor, the thermal shock stability is poor, and it is easy to produce structural spalling; second, the thermal conductivity of high-alumina refractory materials is weak, which hinders the transfer of heat in the boiler and reduces the thermal energy utilization rate of the circulating fluidized bed boiler; three Most of the high-alumina refractories are combined with calcium aluminate cement, which not only reduces the high-temperature strength of the high-alumina refractories, but also makes it difficult to control the hardening rate, which affects the construction.

SUMMARY OF THE INVENTION

The present invention aims to overcome the defects of the prior art, and aims to provide a method for preparing a circulating fluidized bed boiler water-cooled wall castable with a simple process; the circulating fluidized-bed boiler water-cooled wall castable prepared by the method has high strength, high heat Good seismic stability, high thermal conductivity and good construction performance.

To achieve the above object, the concrete steps of the technical scheme adopted in the present invention are:

Step 1. According to the mass ratio of high alumina bauxite clinker:aluminum sol 100:(2～5), the high alumina bauxite clinker and the alumina sol are mixed for 3～5 minutes, and stored for 30 minutes at room temperature. ~40 minutes to make a premix.

Step 2. According to the fine powder of brown corundum: fine powder of magnesium aluminum spinel: fine powder of zirconium corundum: fine powder of ρ-alumina: fine powder of silicon carbide, the mass ratio is 100: (10～15): (2～5) : (5-8): (3-6), the brown corundum fine powder, the magnesia-aluminum spinel fine powder, the zirconium corundum fine powder, the p-alumina fine powder and the carbonized The silicon fine powder is added to the mixer and mixed for 5-8 minutes to obtain fine powder.

Step 3: According to the premix: the mass ratio of the fine powder is 100: (35-40), add the fine powder to the premix, mix for 5-6 minutes, and obtain a mixed solution. material.

Step 4: Add silica sol accounting for 4-5wt% of the mixture to the mixture, stir for 3-5 minutes, and trap the material for 2-3 minutes to obtain the circulating fluidized bed boiler water-cooled wall castable.

The main chemical components of the high-alumina bauxite clinker are: the content of Al ₂ O ₃ is 80-85 wt %, the content of SiO ₂ is 10-12 wt %, and the content of Fe ₂ O ₃ is less than or equal to 1 wt %; The particle size of the material is 0.1 to 6 mm.

The Al ₂ O ₃ content of the aluminum sol is 8-10 wt %.

The Al ₂ O ₃ content of the brown corundum fine powder is greater than or equal to 98 wt %; the particle size of the brown corundum fine powder is 60-80 μm.

The main chemical components of the magnesium-aluminum spinel fine powder are: the content of MgO is 20-30 wt%, the content of Al ₂ O ₃ is 60-70 wt%; the particle size of the fine-magnesium-aluminum spinel powder is 50-70 μm.

The main chemical components of the zirconium corundum fine powder are: Al ₂ O ₃ content is 90-95 wt %, ZrO ₂ content is 3-5 wt %; the particle size of the zirconium corundum fine powder is 40-60 μm.

The Al ₂ O ₃ content of the ρ-alumina fine powder is greater than or equal to 99 wt %; the particle size of the ρ-alumina fine powder is 40-60 μm.

The SiC content of the silicon carbide fine powder is greater than or equal to 98 wt %; the particle size of the silicon carbide fine powder is 40-60 μm.

The SiO ₂ content of the silica sol is 10-15 wt %.

Due to taking the above-mentioned technical scheme, the present invention has the following positive effects compared with the prior art:

1. The present invention only needs to mix and trap the materials according to the mass ratio between the components to obtain the circulating fluidized bed boiler water-cooled wall castable, and does not require special equipment and complicated technical means, and the preparation process is simple.

2. The present invention adopts cement-free combination, which improves the construction performance of the castable for the water-cooled wall of the circulating fluidized bed boiler.

3. The present invention stirs and mixes the mixture and the silica sol evenly, traps the material, enhances the bonding performance between the components of the raw material, and improves the strength of the castable for the water-cooled wall of the circulating fluidized bed boiler.

4. The present invention utilizes the introduction of silicon carbide fine powder to improve the thermal conductivity of the water-cooled wall castable of the circulating fluidized bed boiler, and combines the secondary spinelization reaction of the magnesium-aluminum spinel fine powder and the oxidation of the silicon carbide fine powder- The solid solution reaction improves the strength and thermal shock stability of the castable for the water wall of the circulating fluidized bed boiler.

The water-cooled wall castable of the circulating fluidized bed boiler prepared by the invention has been measured: the compressive strength at room temperature is 40-45MPa; the thermal conductivity is 7.5-8.0W·m ^-1 ·K ^-1 ; the 1100 ℃ water-cooled one-time thermal shock stability experiment The residual strength retention rate was 89 to 94%.

Therefore, the process of the invention is simple; the prepared circulating fluidized bed boiler water-cooled wall castable has high strength, good thermal shock stability, high thermal conductivity and good construction performance.

Detailed ways

The present invention will be further described below with reference to the specific embodiments, which are not intended to limit its protection scope.

In order to avoid repetition, the materials involved in this specific embodiment are described as follows first, and will not be repeated in the examples:

The main chemical components of the high-alumina bauxite clinker are: the content of Al ₂ O ₃ is 80-85 wt %, the content of SiO ₂ is 10-12 wt %, and the content of Fe ₂ O ₃ is less than or equal to 1 wt %; The particle size of the material is 0.1 to 6 mm.

The Al ₂ O ₃ content of the aluminum sol is 8-10 wt %.

The Al ₂ O ₃ content of the brown corundum fine powder is greater than or equal to 98 wt %; the particle size of the brown corundum fine powder is 60-80 μm.

The main chemical components of the magnesium-aluminum spinel fine powder are: the content of MgO is 20-30 wt%, the content of Al ₂ O ₃ is 60-70 wt%; the particle size of the fine-magnesium-aluminum spinel powder is 50-70 μm.

The main chemical components of the zirconium corundum fine powder are: Al ₂ O ₃ content is 90-95 wt %, ZrO ₂ content is 3-5 wt %; the particle size of the zirconium corundum fine powder is 40-60 μm.

The Al ₂ O ₃ content of the ρ-alumina fine powder is greater than or equal to 99 wt %; the particle size of the ρ-alumina fine powder is 40-60 μm.

The SiC content of the silicon carbide fine powder is greater than or equal to 98 wt %; the particle size of the silicon carbide fine powder is 40-60 μm.

The SiO ₂ content of the silica sol is 10-15 wt %.

Example 1

A circulating fluidized bed boiler water-cooled wall castable and a preparation method thereof. The specific steps of the preparation method described in this embodiment are:

Step 1. According to the mass ratio of high alumina bauxite clinker:aluminum sol 100:(2～4), the high alumina bauxite clinker and the alumina sol were mixed for 3～5 minutes, and stored for 30 minutes at room temperature. ~40 minutes to make a premix.

Step 2. According to the fine powder of brown corundum: fine powder of magnesium aluminum spinel: fine powder of zirconium corundum: fine powder of ρ-alumina: fine powder of silicon carbide, the mass ratio is 100: (10～12): (2～4) : (5-7): (3-5), the brown corundum fine powder, the magnesia-aluminum spinel fine powder, the zirconium corundum fine powder, the p-alumina fine powder and the carbonized alumina The silicon fine powder is added to the mixer and mixed for 5-8 minutes to obtain fine powder.

Step 3. According to the premix: the mass ratio of the fine powder is 100: (35-37), add the fine powder to the premix, mix for 5-6 minutes, and obtain a mixed solution. material.

Step 4: Add silica sol accounting for 4-5wt% of the mixture to the mixture, stir for 3-5 minutes, and trap the material for 2-3 minutes to obtain the circulating fluidized bed boiler water-cooled wall castable.

The circulating fluidized bed boiler water-cooled wall castable prepared by this specific embodiment has been measured: the compressive strength at room temperature is 40-42MPa; the thermal conductivity is 7.5-7.7W·m ^-1 ·K ^-1 ; 1100 ℃ water-cooled one-time thermal shock stability The residual strength retention rate of the test is 89-91%.

Example 2

A circulating fluidized bed boiler water-cooled wall castable and a preparation method thereof. The specific steps of the preparation method described in this embodiment are:

Step 1. According to the mass ratio of high alumina bauxite clinker:aluminum sol 100:(2～4), the high alumina bauxite clinker and the alumina sol were mixed for 3～5 minutes, and stored for 30 minutes at room temperature. ~40 minutes to make a premix.

Step 2. According to the fine powder of brown corundum: fine powder of magnesium aluminum spinel: fine powder of zirconium corundum: fine powder of ρ-alumina: fine powder of silicon carbide, the mass ratio is 100: (11～13): (2～4) : (5-7): (3-5), the brown corundum fine powder, the magnesia-aluminum spinel fine powder, the zirconium corundum fine powder, the p-alumina fine powder and the carbonized alumina The silicon fine powder is added to the mixer and mixed for 5-8 minutes to obtain fine powder.

Step 3: According to the premix: the mass ratio of the fine powder is 100: (36-38), add the fine powder to the premix, and mix for 5-6 minutes to obtain a mixed solution. material.

Step 4: Add silica sol accounting for 4-5wt% of the mixture to the mixture, stir for 3-5 minutes, and trap the material for 2-3 minutes to obtain the circulating fluidized bed boiler water-cooled wall castable.

The circulating fluidized bed boiler water-cooled wall castable prepared by this specific embodiment has been measured: the compressive strength at room temperature is 41-43MPa; the thermal conductivity is 7.6-7.8W·m ^-1 ·K ^-1 ; 1100 ℃ water-cooled one-time thermal shock stability The residual strength retention rate of the test is 90-92%.

Example 3

A circulating fluidized bed boiler water-cooled wall castable and a preparation method thereof. The specific steps of the preparation method described in this embodiment are:

Step 1, according to the mass ratio of high alumina bauxite clinker:aluminum sol is 100:(3～5), mix described high alumina bauxite clinker and described alumina sol for 3～5 minutes, store 30 minutes at room temperature. ~40 minutes to make a premix.

Step 2. According to the fine powder of brown corundum: fine powder of magnesium aluminum spinel: fine powder of zirconium corundum: fine powder of ρ-alumina: fine powder of silicon carbide, the mass ratio is 100: (12～14): (3～5) : (6-8): (4-6), the brown corundum fine powder, the magnesia-aluminum spinel fine powder, the zirconium corundum fine powder, the p-alumina fine powder and the carbonized The silicon fine powder is added to the mixer and mixed for 5-8 minutes to obtain fine powder.

Step 3. According to the premix: the mass ratio of the fine powder is 100: (37-39), add the fine powder to the premix, mix for 5-6 minutes, and obtain a mixed solution. material.

Step 4: Add silica sol accounting for 4-5wt% of the mixture to the mixture, stir for 3-5 minutes, and trap the material for 2-3 minutes to obtain the circulating fluidized bed boiler water-cooled wall castable.

The circulating fluidized bed boiler water-cooled wall castable prepared by this specific embodiment is measured: the compressive strength at room temperature is 42-44MPa; the thermal conductivity is 7.7-7.9W·m ^-1 ·K ^-1 ; 1100 ℃ water-cooled one-time thermal shock stability The residual strength retention rate of the test is 91-93%.

Example 4

A circulating fluidized bed boiler water-cooled wall castable and a preparation method thereof. The specific steps of the preparation method described in this embodiment are:

Step 1, according to the mass ratio of high alumina bauxite clinker:aluminum sol is 100:(3～5), mix described high alumina bauxite clinker and described alumina sol for 3～5 minutes, store 30 minutes at room temperature. ~40 minutes to make a premix.

Step 2. According to the fine powder of brown corundum: fine powder of magnesium aluminum spinel: fine powder of zirconium corundum: fine powder of ρ-alumina: fine powder of silicon carbide, the mass ratio is 100: (13～15): (3～5) : (6-8): (4-6), the brown corundum fine powder, the magnesia-aluminum spinel fine powder, the zirconium corundum fine powder, the p-alumina fine powder and the carbonized The silicon fine powder is added to the mixer and mixed for 5-8 minutes to obtain fine powder.

Step 3. According to the premix: the mass ratio of the fine powder is 100: (38-40), add the fine powder to the premix and mix for 5-6 minutes to obtain a mixed solution. material.

Step 4: Add silica sol accounting for 4-5wt% of the mixture to the mixture, stir for 3-5 minutes, and trap the material for 2-3 minutes to obtain the circulating fluidized bed boiler water-cooled wall castable.

The circulating fluidized bed boiler water-cooled wall castable prepared by this specific embodiment has been measured: the compressive strength at room temperature is 43-45MPa; the thermal conductivity is 7.8-8.0W·m ^-1 ·K ^-1 ; 1100 ℃ water-cooled one-time thermal shock stability The residual strength retention rate of the test is 92-94%.

Compared with the prior art, this specific embodiment has the following positive effects:

1. This specific embodiment only needs to mix and trap the materials according to the mass ratio between the components to obtain the circulating fluidized bed boiler water-cooled wall castable, and does not require special equipment and complex technical means, and the preparation process is simple.

2. This specific embodiment adopts cement-free bonding, which improves the construction performance of the castable for the water-cooled wall of the circulating fluidized bed boiler.

3. In this specific embodiment, the mixture and the silica sol are stirred and mixed evenly, so as to trap the material, enhance the bonding performance between the components of the raw material, and improve the strength of the castable for the water wall of the circulating fluidized bed boiler.

4. This specific embodiment utilizes the introduction of silicon carbide fine powder to improve the thermal conductivity of the water-cooled wall castable of the circulating fluidized bed boiler, and combines the secondary spinelization reaction of the magnesium-aluminum spinel fine powder with the silicon carbide fine powder. The oxidation-solid solution reaction improves the strength and thermal shock stability of the castable for the water wall of the circulating fluidized bed boiler.

The circulating fluidized bed boiler water-cooled wall castable prepared by this specific embodiment has been measured: the compressive strength at room temperature is 40-45MPa; the thermal conductivity is 7.5-8.0W·m ^-1 ·K ^-1 ; 1100 ℃ water-cooled one-time thermal shock stability The residual strength retention rate of the test is 89-94%.

Therefore, the process of this specific embodiment is simple; the prepared CFB boiler water-cooled wall castable has high strength, good thermal shock stability, high thermal conductivity and good construction performance.

Claims (8)

1. A preparation method of a circulating fluidized bed boiler water wall castable is characterized by comprising the following specific steps:

step one, mixing the bauxite clinker and the alumina sol for 3-5 minutes according to the mass ratio of the bauxite clinker to the alumina sol being 100: 2-5, and storing for 30-40 minutes at room temperature to obtain a premix;

step two, adding brown corundum fine powder, magnesia alumina spinel fine powder, zirconium corundum fine powder and silicon carbide fine powder into a stirrer, and mixing for 5-8 minutes to obtain fine powder, wherein the mass ratio of the brown corundum fine powder to the magnesium aluminate spinel fine powder to the zirconium corundum fine powder to the rho-alumina fine powder to the silicon carbide fine powder is 100: 10-15: 2-5: 5-8: 3-6;

step three, adding the fine powder into the premix according to the mass ratio of the premix to the fine powder of 100: 35-40, and mixing for 5-6 minutes to obtain a mixture;

step four, adding silica sol which accounts for 4-5 wt% of the mixture into the mixture, stirring for 3-5 minutes, and ageing for 2-3 minutes to obtain the circulating fluidized bed boiler water wall castable;

al of the aluminum sol₂O₃The content is 8-10 wt%;

the magnesium aluminate spinel fine powder mainly comprises the following chemical components: MgO content of 20-30 wt%, Al₂O₃The content is 60-70 wt%; the particle size of the magnesia-alumina spinel fine powder is 50-70 mu m;

the granularity of the zirconia corundum fine powder is 40-60 mu m;

the granularity of the rho-alumina fine powder is 40-60 mu m;

the granularity of the silicon carbide fine powder is 40-60 mu m.

2. The method for preparing the castable for the water wall of the circulating fluidized bed boiler according to claim 1, wherein the main chemical components of the bauxite chamotte are as follows: al (Al)₂O₃80-85 wt% of SiO₂10-12 wt% of Fe₂O₃The content is less than or equal to 1 wt%; the particle size of the bauxite chamotte is 0.1-6 mm.

3. The method for preparing the castable for the water wall of the circulating fluidized bed boiler according to claim 1, wherein the Al of the brown corundum fine powder₂O₃The content is more than or equal to 98 wt%; the particle size of the brown corundum fine powder is 60-80 mu m.

4. The method for preparing the castable for the water wall of the circulating fluidized bed boiler according to claim 1, wherein the zirconia corundum fine powder mainly comprises the following chemical components: al (Al)₂O₃90-95 wt% of ZrO₂The content is 3-5 wt%.

5. The method of preparing a circulating fluidized bed boiler water wall castable according to claim 1, wherein the p-oxidation is performedAl of fine aluminum powder₂O₃The content is more than or equal to 99 wt%.

6. The preparation method of the castable for the water wall of the circulating fluidized bed boiler according to claim 1, wherein the SiC content of the silicon carbide fine powder is not less than 98 wt%.

7. The method for preparing a circulating fluidized bed boiler water wall castable according to claim 1, wherein SiO of the silica sol₂The content is 10-15 wt%.

8. A circulating fluidized bed boiler water wall castable, which is characterized by being prepared according to the preparation method of the circulating fluidized bed boiler water wall castable in any one of claims 1-7.