A sludge-based high-strength erosion-resistant heat-insulating material for flues and a preparation method thereof

Abstract

The application discloses a sludge-based high-strength flue anti-erosion heat insulation material and a preparation method thereof. The heat insulation material comprises the following components in percentage by mass: 30-40% of vitrified microbeads, 4-6% of redispersible emulsion powder, 2-5% of silicon carbide powder, 1-3% of a surfactant, 0.1-0.2% of hydantoin thiourea tryptophan, and the rest of sludge. The preparation method of the heat insulation material comprises the following steps: S1, stirring and mixing; S2, aging and drying; and S3, sintering and cooling. The prepared heat insulation material realizes resource utilization of the sludge, has excellent anti-erosion performance and heat insulation performance, and can prolong the service life of the high-strength flue.

Description

Technical Field

[0001] This invention relates to the field of thermal insulation materials, specifically to a sludge-based high-strength anti-corrosion thermal insulation material for flues and its preparation method. Background Technology

[0002] In buildings and industrial facilities, smoke exhaust ducts are crucial components. Thermal insulation is a key element in ensuring the effective operation of smoke exhaust systems. Insulation measures not only improve smoke exhaust efficiency but also protect the ducts from heat radiation, reducing energy consumption.

[0003] Choosing the right insulation material is crucial for the insulation effect of flue gas ducts. Common insulation materials include rock wool, fiberglass, and aluminum silicate fiber. These materials have good insulation properties and high-temperature resistance, effectively reducing heat conduction and radiation.

[0004] However, when flue gas comes into high-intensity contact with the flue gas, the flue gas material is easily corroded by the flue gas at high temperatures, thereby impairing the flue gas exhaust efficiency. Therefore, this invention improves the above problems by preparing sludge-based insulation materials. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a sludge-based high-strength anti-corrosion insulation material for flues and its preparation method.

[0006] The technical solution of the present invention is: a sludge-based high-strength anti-corrosion insulation material for flues, comprising the following components by mass percentage: 30-40% vitrified microspheres, 4-6% redispersible latex powder, 2-5% silicon carbide powder, 1-3% surfactant, 0.1-0.2% acetamide thiourea tryptophan, and the balance sludge.

[0007] Furthermore, the sludge is either municipal sludge or papermaking sludge.

[0008] Note: Replacing some clay with urban sludge or papermaking sludge as raw material for flue insulation not only allows for the resource-based treatment of solid waste, but also meets the demand for lightweight and improved insulation performance in insulation materials.

[0009] Furthermore, the vitrified microspheres have a particle size of 0.4–0.7 mm, and the silicon carbide powder has a particle size of 45–55 μm.

[0010] Note: Raw materials with large particle sizes are difficult to compress, while raw materials that are too fine will result in too much powder mixed in the finished product, and the particles will be extremely dense and hard, making them difficult to process later.

[0011] Furthermore, the surfactant is one of sodium dodecylbenzenesulfonate, sodium fatty alcohol polyoxyethylene ether sulfate, or lecithin.

[0012] Note: By selecting the surfactants mentioned above, the activity of the sludge can be improved, thereby increasing the uniformity of the mixing between the sludge and materials such as silicon carbide, and increasing the reaction rate of subsequent aging treatment.

[0013] According to any one of the above-mentioned sludge-based high-strength corrosion-resistant insulation materials for flues, the following steps are included:

[0014] S1. Stir and mix:

[0015] After the sludge is dehydrated and dried to a moisture content of 35-45%, vitrified microspheres, redispersible latex powder and sludge are mixed evenly in sequence and then ground to obtain a first mixture; then silicon carbide powder and surfactant are added to the first mixture and mixed evenly, and then ground to obtain a second mixture.

[0016] S2. Aging and drying:

[0017] Add hydantoin thiourea to the second mixture obtained in step S1 and mix evenly. After stirring, carry out a first-stage aging under a negative pressure of -35 to -20 kPa for 10 to 13 days. Then, homogenize the mixture for 4 to 6 minutes at 45 to 50°C and 18 to 22 MPa. After homogenization, dry the mixture at 70 to 80°C for 40 to 50 minutes to obtain the first-stage aged product.

[0018] The first-stage aged product is then subjected to a second-stage aging under infrared irradiation conditions. After the second-stage aging is carried out for 8 to 10 days, it is spray-dried to obtain the second-stage aged product.

[0019] The infrared irradiation is characterized by a wavelength of 800 nm to 1 μm, a distance of 30 to 45 cm between the infrared light source and a section of aged product, and an intensity of 250 to 950 W / m². 2 Infrared irradiation;

[0020] S3, Sintering and Cooling:

[0021] After step S2 is completed, the two-stage aging product is pressed into shape to obtain a blank; the blank is sintered at 950-1100℃ for 70-90 min, and then cooled to room temperature at a cooling rate of 5-8℃ / min to obtain the heat insulation material.

[0022] Further, in step S1, the sludge dewatering and drying includes the following steps:

[0023] S1-1: First, crush the sludge at a speed of 1200-1400 r / min to obtain crushed sludge of 5-10 mm;

[0024] S1-2: Add the deodorizing bacteria agent to the crushed sludge and catalytically hydrolyze for 45-55 minutes; wherein the mass ratio of the deodorizing bacteria agent to the crushed sludge is 1:80-90, the catalytic hydrolysis pressure is 1.5-2.5 MPa, and the temperature is maintained at 210-220℃.

[0025] S1-3: The sludge obtained by catalytic hydrolysis is centrifuged at a speed of 2600-2800 r / min for 10-15 min to separate solid and liquid and obtain centrifuged sludge. The centrifuged sludge is then pressed and dried to a moisture content of 35-45%.

[0026] Explanation: Crushing the sludge increases the contact area between the sludge and the deodorizing agent, thereby improving the deodorization effect. The deodorizing agent catalytically hydrolyzes the sludge, degrading organic pollutants in the sludge into smaller organic molecules. Through hydrolysis, certain harmful substances such as heavy metals and organic matter are decomposed by microorganisms in the deodorizing agent, reducing the environmental harm of the sludge. The hydrolysis process decomposes the organic matter in the sludge, thus facilitating better pressure filtration and drying.

[0027] Furthermore, the deodorizing agent comprises *Lactobacillus plantarum* and *Pichia pastoris* fermented in a live bacteria ratio of 1:2 to 5, and the live bacteria concentration in the deodorizing agent is 4.5 to 5.0 × 8⁸. 10 CFU / mL.

[0028] Note: These two microorganisms not only have excellent deodorizing performance, but also strong environmental adaptability: they can adapt to a wide range of temperatures and humidity; they can effectively inhibit the growth of odor-producing bacteria, pathogens and other miscellaneous bacteria, and efficiently degrade malodorous gases such as ammonia and hydrogen sulfide, thus having a significant deodorizing effect.

[0029] Furthermore, in steps S1 and S2, the operation of mixing evenly is as follows: stirring at a speed of 120-130 r / min for 16-18 min.

[0030] Note: If the stirring speed is too low or the stirring time is too short, the mixture will be uneven. If the stirring speed is too high or the stirring time is too long, it may damage the sludge structure.

[0031] Further, in step S2, the first drying is performed at 70-80°C for 40-50 minutes; the second drying is performed at 50-60°C for 25-35 minutes.

[0032] Note: If the drying temperature is too low or the drying time is too short, the aged product will have too much moisture and will be easily dissolved; if the drying temperature is too high or the drying time is too long, the aged product will be prone to cracking and deformation.

[0033] Furthermore, in step S3, the pressure for pressing and molding is 5 to 10 MPa.

[0034] Explanation: If the molding pressure is too low, the density of the blank will be insufficient and the strength of the blank will be poor, which will not meet the requirements of subsequent processes; if the molding pressure is too high, the residual air in the blank will be compressed, and when the pressure is released, the expansion of the compressed air will cause delamination.

[0035] The beneficial effects of this invention are:

[0036] (1) This invention uses sludge as a base material to prepare flue insulation material, thereby realizing the resource utilization of sludge and having good social benefits. During the sintering and cooling process of sludge, toxic heavy metals can be sealed in the insulation material, killing harmful bacteria. Moreover, the insulation material made from sludge is lightweight and has many pores, which has certain advantages such as sound insulation and heat insulation.

[0037] (2) The insulation material of the present invention improves the insulation and anti-corrosion properties of sludge by adding vitrified microspheres and redispersible latex powder, and improves the anti-corrosion properties by adding silicon carbide powder. The addition of surfactants improves the reaction rate and mixing uniformity of sludge during the preparation process. The addition of acetamide thiourea tryptophan can promote the degradation and decomposition of organic matter in sludge, and can inhibit the growth and metabolism of microorganisms at a certain concentration, thus inhibiting the growth of bacteria, viruses and other microorganisms in sludge, which helps to reduce the potential risks of sludge.

[0038] (3) The method for preparing the heat insulation material of the present invention can promote the degradation of organic matter and provide favorable conditions for the growth of aging microorganisms by aging the raw materials under negative pressure for a first stage, thereby accelerating the degradation rate of organic matter; at the same time, the high temperature generated during the negative pressure aging process can also kill pathogens; the second stage of aging under infrared irradiation can heat the sludge in an efficient manner and increase its temperature, while the high temperature can promote the degradation of organic matter and accelerate the aging process, shortening the treatment time; and infrared irradiation has a certain disinfection effect, which can inhibit the growth of pathogens in the sludge. Detailed Implementation

[0039] The present invention will now be described in more detail with reference to specific embodiments, so as to better demonstrate the advantages of the present invention.

[0040] Example 1

[0041] A sludge-based high-strength anti-corrosion insulation material for flues comprises the following components by weight percentage: 35% vitrified microspheres, 5% redispersible latex powder, 3.5% silicon carbide powder, 2% surfactant, 0.15% acetamide thiourea tryptophan, and the balance being municipal sludge.

[0042] The vitrified microspheres have a particle size of 0.5–0.6 mm, the silicon carbide powder has a particle size of 48–52 μm, and the surfactant is sodium dodecylbenzene sulfonate.

[0043] The preparation method of the above-mentioned sludge-based high-strength anti-corrosion insulation material for flues includes the following steps:

[0044] S1. Stir and mix:

[0045] After dewatering and drying the municipal sludge to a moisture content of 40%, vitrified microspheres and redispersible latex powder are mixed evenly with the municipal sludge in sequence, and then ground to obtain a first mixture; then silicon carbide powder and surfactant are added to the first mixture and mixed evenly, and then ground to obtain a second mixture;

[0046] Urban sludge dewatering and drying includes the following steps:

[0047] S1-1: First, crush the municipal sludge at a speed of 1300 r / min to obtain crushed sludge of 6-8 mm;

[0048] S1-2: Add the deodorizing agent to the crushed sludge and catalytically hydrolyze for 50 minutes; wherein the mass ratio of the deodorizing agent to the crushed sludge is 1:85, the catalytic hydrolysis pressure is 2.0 MPa, and the temperature is maintained at 215℃.

[0049] The deodorizing agent comprises *Lactobacillus plantarum* and *Pichia pastoris* fermented at a live bacteria ratio of 1:3.5, and the live bacteria concentration in the deodorizing agent is 4.8 × 8⁸. 10 CFU / mL;

[0050] S1-3: The sludge obtained by catalytic hydrolysis is centrifuged at 2700 r / min for 13 min to separate solid and liquid and obtain centrifuged sludge. The centrifuged sludge is then pressed and dried to a moisture content of 40%.

[0051] S2. Aging and drying:

[0052] Add hydantoin thiourea to the second mixture obtained in step S1 and mix evenly. After stirring, it is aged under a negative pressure of -28 kPa for 12 days. After aging, it is homogenized at 48℃ and 20 MPa for 5 minutes. After homogenization, it is dried once to obtain the first-stage aged product.

[0053] The first-stage aged product is then subjected to a second-stage aging under infrared irradiation conditions. After the second-stage aging for 8-10 days, it is dried a second time to obtain the second-stage aged product.

[0054] The infrared irradiation was performed with a wavelength of 900 nm, a distance of 38 cm between the infrared light source and a section of aged product, and an intensity of 600 W / m². 2 Infrared irradiation;

[0055] The first drying is performed at 75°C for 45 minutes; the second drying is performed at 55°C for 30 minutes; in steps S1 and S2, the mixing process is performed by stirring at 125 r / min for 17 minutes.

[0056] S3, Sintering and Cooling:

[0057] After step S2 is completed, the two-stage aging product is pressed into shape at a pressure of 8 MPa to obtain a green body; the green body is sintered at 1025℃ for 80 min and then cooled to room temperature at a cooling rate of 6.5℃ / min to obtain a heat insulation material.

[0058] Example 2

[0059] The difference between this embodiment and Embodiment 1 is that the heat insulation material comprises the following components by mass percentage: 30% vitrified microspheres, 4% redispersible latex powder, 2% silicon carbide powder, 1% sodium fatty alcohol polyoxyethylene ether sulfate, 0.1% acetamide thiourea tryptophan, and the balance being papermaking sludge.

[0060] Example 3

[0061] The difference between this embodiment and Embodiment 1 is that the insulation material comprises the following components by mass percentage: 40% vitrified microspheres, 6% redispersible latex powder, 5% silicon carbide powder, 3% lecithin, 0.2% acetamide thiourea tryptophan, and the balance being municipal sludge.

[0062] Example 4

[0063] The difference between this embodiment and Embodiment 1 is that the particle size of the vitrified microspheres is 0.4-0.5 mm, and the particle size of the silicon carbide powder is 45-50 μm.

[0064] Example 5

[0065] The difference between this embodiment and Embodiment 1 is that the particle size of the vitrified microspheres is 0.5-0.7 mm, and the particle size of the silicon carbide powder is 50-55 μm.

[0066] Example 6

[0067] The difference between this embodiment and embodiment 1 is that in step S1-1, the urban sludge is first crushed at a speed of 1200 r / min to obtain crushed sludge of 5-7 mm.

[0068] Example 7

[0069] The difference between this embodiment and embodiment 1 is that in step S1-1, the urban sludge is first crushed at a speed of 1400 r / min to obtain crushed sludge of 7-10 mm.

[0070] Example 8

[0071] The difference between this embodiment and embodiment 1 is that in steps S1-2, the deodorizing bacteria agent is added to the crushed sludge in proportion and catalytically hydrolyzed for 45 minutes; wherein, the pressure of catalytic hydrolysis is 1.5 MPa and the temperature is maintained at 210℃.

[0072] Example 9

[0073] The difference between this embodiment and embodiment 1 is that in steps S1-2, the deodorizing bacteria agent is added to the crushed sludge in proportion and catalytically hydrolyzed for 55 minutes; wherein, the pressure of catalytic hydrolysis is 2.5 MPa and the temperature is maintained at 220°C.

[0074] Example 10

[0075] The difference between this embodiment and Embodiment 1 is that, in steps S1-2, the deodorizing agent comprises *Lactobacillus plantarum* and *Pichia pastoris* in a live bacteria ratio of 1:2, and the live bacteria concentration in the deodorizing agent is 4.5 × 8⁸. 10 The deodorizing agent and the crushed sludge have a mass ratio of CFU / mL and a mass ratio of 1:80.

[0076] Example 11

[0077] The difference between this embodiment and Embodiment 1 is that, in steps S1-2, the deodorizing agent comprises *Lactobacillus plantarum* and *Pichia pastoris* in a live bacteria ratio of 1:5, and the live bacteria concentration in the deodorizing agent is 5.0 × 8⁸. 10 CFU / mL, wherein the mass ratio of the deodorizing agent to the crushed sludge is 1:90.

[0078] Example 12

[0079] The difference between this embodiment and Embodiment 1 is that in steps S1-3, the sludge obtained by catalytic hydrolysis is centrifuged at 2600 r / min for 10 min to separate the solid and liquid and obtain centrifuged sludge. The centrifuged sludge is then pressed and dried to a moisture content of 45%.

[0080] Example 13

[0081] The difference between this embodiment and Embodiment 1 is that in steps S1-3, the sludge obtained by catalytic hydrolysis is centrifuged at a speed of 2800 r / min for 15 min to separate the solid and liquid and obtain centrifuged sludge. The centrifuged sludge is then pressed and dried to a moisture content of 35%.

[0082] Example 14

[0083] The difference between this embodiment and Embodiment 1 is that, in steps S1 and S2, the operation of mixing evenly is: stirring at a speed of 120 r / min for 16 min.

[0084] Example 15

[0085] The difference between this embodiment and embodiment 1 is that, in steps S1 and S2, the operation of mixing evenly is: stirring at a speed of 130 r / min for 18 min.

[0086] Example 16

[0087] The difference between this embodiment and embodiment 1 is that in step S2, a period of aging is carried out under a negative pressure of -20 kPa for 10 days.

[0088] Example 17

[0089] The difference between this embodiment and embodiment 1 is that in step S2, a period of aging is carried out under a negative pressure of -35 kPa for 13 days.

[0090] Example 18

[0091] The difference between this embodiment and embodiment 1 is that in step S2, after a period of aging, the material is homogenized for 4 minutes at 45°C and 18MPa.

[0092] Example 19

[0093] The difference between this embodiment and embodiment 1 is that in step S2, after a period of aging, the material is homogenized at 50°C and 22MPa for 6 minutes.

[0094] Example 20

[0095] The difference between this embodiment and Embodiment 1 is that, in step S2, the first-stage aged product is subjected to a second-stage aging under infrared irradiation conditions for 8 days; the infrared irradiation is characterized by a wavelength of 800 nm, a distance of 45 cm between the infrared light source and the first-stage aged product, and an intensity of 250 W / m². 2 Infrared irradiation.

[0096] Example 21

[0097] The difference between this embodiment and Embodiment 1 is that, in step S2, the first-stage aged product is subjected to a second-stage aging process under infrared irradiation for 10 days; the infrared irradiation is characterized by a wavelength of 1 μm, a distance of 30 cm between the infrared light source and the first-stage aged product, and an intensity of 950 W / m². 2 Infrared irradiation.

[0098] Example 22

[0099] The difference between this embodiment and Embodiment 1 is that in step S2, the first drying is performed at 70°C for 40 minutes; the second drying is performed at 500°C for 25 minutes.

[0100] Example 23

[0101] The difference between this embodiment and Embodiment 1 is that in step S2, the first drying is performed at 80°C for 50 minutes, and the second drying is performed at 60°C for 35 minutes.

[0102] Example 24

[0103] The difference between this embodiment and embodiment 1 is that in step S3, the two-stage aging product is pressed and formed at 5 MPa to obtain a blank; the blank is sintered at 950°C for 70 min, and then cooled to room temperature at a cooling rate of 5°C / min to obtain the heat insulation material.

[0104] Example 25

[0105] The difference between this embodiment and embodiment 1 is that in step S3, the two-stage aging product is pressed and formed at 10 MPa to obtain a blank; the blank is sintered at 1100℃ for 90 min, and then cooled to room temperature at a cooling rate of 8℃ / min to obtain the heat insulation material.

[0106] Experimental Example

[0107] For the thermal insulation materials prepared in each embodiment, five samples were taken from each embodiment to test the erosion resistance and thermal insulation performance of the thermal insulation materials. The average value of the performance measurement results of the five samples in each embodiment was taken as the performance measurement result of that embodiment. The specific investigation is as follows:

[0108] 1. The influence of the raw materials and proportions of thermal insulation materials on the erosion resistance and thermal conductivity of thermal insulation materials.

[0109] Table 1. Effects of Examples 1-5 on the erosion resistance (%) and thermal conductivity (W / m·K) of the insulation material

[0110] Group Example 1 Example 2 Example 3 Example 4 Example 5 Erosion resistance 99.4 98.7 99.1 98.4 98.8 thermal conductivity 0.04 0.09 0.06 0.08 0.09

[0111] As shown in Table 1, too small or too large a sludge ratio, and too small or too large a particle size of vitrified microspheres and silicon carbide powder will reduce the erosion resistance of the insulation material and increase the thermal conductivity. Therefore, in comparison, the parameters of Example 1 are relatively better.

[0112] 2. The effect of sludge pretreatment in insulation materials on the erosion resistance and thermal conductivity of insulation materials.

[0113] Table 2 shows the effects of Examples 6-13 on the erosion resistance (%) and thermal conductivity (W / m·K) of the insulation material.

[0114]

[0115] As shown in Table 2, during sludge pretreatment, excessively small or large crushing degree, excessively small or large catalytic hydrolysis parameters, excessively small or large composition and proportion of deodorizing bacteria agent, and excessively small or large centrifugal drying parameters will all reduce the erosion resistance of the insulation material and increase the thermal conductivity. Therefore, compared with the previous example, Example 1 is relatively better.

[0116] 3. The influence of the preparation parameters of the insulation material on the erosion resistance and thermal conductivity of the insulation material.

[0117] Table 3 shows the effects of Examples 14-25 and Comparative Examples 1-3 on the erosion resistance (%) and thermal conductivity (W / m·K) of the insulation material.

[0118]

[0119] The difference between Comparative Example 1 and Example 1 is that in step S2, only one aging process is performed;

[0120] The difference between Comparative Example 2 and Example 1 is that in step S2, no homogenization treatment was performed after a period of aging;

[0121] The difference between Comparative Example 3 and Example 1 is that infrared irradiation was not used during the second-stage aging in step S2;

[0122] As shown in Table 3, the lack of two-stage aging in Control Example 1, the lack of homogenization treatment in Control Example 2, and the lack of infrared irradiation in Control Example 3 all significantly reduced the erosion resistance and increased the thermal conductivity of the insulation material compared to Examples 1-25.

[0123] Comparing Examples 1 and 14-25, it can be seen that if the parameters for uniform mixing, negative pressure aging, homogenization, two-stage aging and infrared irradiation, primary and secondary drying, and sintering and cooling are too small or too large, the erosion resistance of the insulation material will be reduced and the thermal conductivity will be increased. Therefore, from an economic point of view, Example 1 is relatively the most effective.

Claims

1. A sludge-based high strength erosion resistant insulating material for flues, characterized in that, The preparation method of the above-mentioned high-strength flue erosion-resistant heat insulation material comprises the following steps: The preparation method of the above-mentioned high-strength flue erosion-resistant heat insulation material comprises the following steps: S1, stirring and mixing: After the sludge is dewatered and dried to a water content of 35-45%, vitrified microbeads, redispersible emulsion powder and sludge are sequentially mixed uniformly, and a first mixture is obtained by pulverizing; then, silicon carbide powder and a surfactant are added to the first mixture and mixed uniformly, and a second mixture is obtained by pulverizing; S2, aging and drying: After the hydantoin thiourea tryptophan is added to the second mixture obtained in step S1 and mixed uniformly, a first aging is performed under a negative pressure of-35 to-20 kPa; after the first aging for 10-13 days, a homogenization treatment is performed at 45-50 DEG C and 18-22 MPa for 4-6 min; after the homogenization treatment is completed, a first drying is performed, and a first aging product is obtained; Then, a second aging is performed on the first aging product under infrared irradiation; after the second aging for 8-10 days, a second drying is performed, and a second aging product is obtained; The infrared irradiation has a wavelength of 800 nm to 1 μm, an infrared light source distance of 30-45 cm from the first aging product, and an intensity of 250-950 W / m2; S3, sintering and cooling: After step S2 is completed, the second aging product is pressed and formed, the pressure of the pressed and formed product is 5-10 MPa, and a green body is obtained; the green body is sintered at 950-1100 DEG C for 70-90 min, and then cooled to room temperature at a cooling rate of 5-8 DEG C / min, and a heat insulation material is obtained. The particle size of the vitrified microbeads is 0.4-0.7 mm, and the particle size of the silicon carbide powder is 45-55 μm.

2. A sludge-based high strength erosion resistant insulating material for flues according to claim 1, characterized in that, In steps S1 and S2, the operation of mixing uniformly is stirring at a speed of 120-130 r / min for 16-18 min.

3. A sludge-based high strength erosion resistant insulating material for flues according to claim 1, wherein In step S2, the first drying is performed at 70-80 DEG C for 40-50 min, and the second drying is performed at 50-60 DEG C for 25-35 min.

4. A sludge-based high strength erosion resistant insulating material for flues according to claim 1, wherein In step S3, the pressure of the pressed and formed product is 5-10 MPa.

5. A sludge-based high strength erosion resistant insulating material for flues according to claim 1, wherein ​

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