Expansion compensation daub as well as preparation method and application thereof

Abstract

The invention discloses expansion compensation daub as well as a preparation method and application thereof. The expansion compensation daub is prepared by mixing polytetrafluoroethylene powder with a large expansion coefficient as a main material and KPI powder with a small expansion coefficient, graphite powder, silicon carbide powder and corundum powder as auxiliary materials, wherein the ratio of the polytetrafluoroethylene powder is 1%-99%; the proportion of the KPI powder is 0-90%; the graphite powder accounts for 0-90%; the silicon carbide powder accounts for 0-50%; and the corundum powder accounts for 0-50%. According to the invention, the expansion compensation daub with settable expansion coefficient is filled between the linings of the outer wall of the equipment to ensure that the outer wall structure is continuous and stable at various temperatures, so that the service life of the equipment is not influenced under the condition of heat preservation of the steel shell.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermal expansion absorption and compensation, in particular to manufacturing materials and technologies for equipment working in acidic and / or alkaline environments, and specifically relates to an expansion compensation mortar and a preparation method and application thereof. Background Art

[0002] Modern metallurgical and chemical equipment shells are increasingly using composite structures of metal and non-metal materials to achieve goals that are difficult to achieve with a single material. However, the thermal expansion coefficients of metal and non-metal materials vary greatly. When the operating temperature of the equipment changes, it is very likely that the two layers of material that were originally bonded together will separate or even create a gap due to the difference in the size of the expansion or contraction of the two. The greater the temperature change, the greater the difference in the expansion coefficient of the materials, and the greater the probability of such separation. The separation of the bond, especially the generation of gaps, will seriously undermine the stability of the composite structure of the outer wall, thereby affecting the safety of use and service life of the equipment.

[0003] There are currently two common methods to solve the stability problem: (1) try to reduce the operating temperature of the steel shell; because the expansion coefficient of the steel shell is large, the expansion space generated after thermal expansion is also large. The outer wall structure materials such as the anti-corrosion layer, thermal insulation layer, and wear-resistant layer behind it are either thin or have small expansion coefficients and are difficult to generate sufficient thermal expansion incremental volume to fill the incremental expansion space generated by the steel shell, thus causing deformation of the outer wall structure; the incremental expansion space of the thermal expansion (or contraction) of the steel shell is proportional to its operating temperature. Therefore, reducing the operating temperature of the steel shell as much as possible can reduce the degree of deformation of the shell wall structure; There are three ways to reduce the shell temperature: One is to increase the thickness of the lining filling layer and the wear-resistant layer to increase the thermal resistance of the shell wall; the cost of this solution is to increase the size of the equipment, increase the volume and weight of the equipment, and thus increase the manufacturing and installation costs; The second is to strengthen the ventilation and cooling of the surface; the cost is the loss of a large amount of heat energy, which increases the cost of equipment use; The third is to reduce the operating temperature inside the equipment; the cost is reduced production efficiency and even reduced product quality; (2) Increase the structural strength of the lining filling layer and the wear-resistant layer, and rely on their own structural strength to reduce structural deformation. However, this method is not only very costly, but also not very effective. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and to provide an expansion compensation mortar and a preparation method and application thereof, so as to use the thermal expansion incremental volume generated by the expansion compensation mortar in a timely manner to compensate for the thermal expansion incremental space generated by the steel shell, thereby ensuring that the shell wall structure is always stable.

[0005] To achieve the above purpose, the present application provides the following technical solution: an expansion compensation mortar, wherein the expansion compensation mortar is mixed with polytetrafluoroethylene powder with a large expansion coefficient as a main material and at least one powder with a small expansion coefficient as an auxiliary material, wherein the auxiliary materials with a small expansion coefficient are: KPI powder, graphite powder, silicon carbide powder, and corundum powder; wherein, Polytetrafluoroethylene powder accounts for 1%~99%; KPI powder accounts for 0~90%; graphite powder accounts for 0~90%; silicon carbide powder accounts for 0~50%; corundum powder accounts for 0~50%.

[0006] As a further improvement of the present application, the binder of the expansion compensation mortar is water glass or asphalt or acid-resistant resin.

[0007] As a further improvement of the present application, the expansion compensation mortar used in an acidic environment has a formula of: polytetrafluoroethylene powder + KPI powder + silicon carbide powder or corundum powder, with water glass or acid-resistant resin as a binder.

[0008] As a further improvement of the present application, the expansion compensation mortar used in an alkaline or acid-base alternating environment has a formula of: polytetrafluoroethylene powder + graphite powder + corundum powder, with asphalt as a binder.

[0009] To achieve the above purpose, the present application also provides the following technical solution: a method for preparing the above expansion compensation mortar, the steps are as follows: Step 1: Calculate the theoretical expansion coefficient required for the expansion compensation mortar according to the designed expansion compensation layer thickness; Step 2: Determine the engineering expansion coefficient based on the theoretical expansion coefficient calculated in step 1; Step 3: Calculate the proportion of each material based on the determined engineering expansion coefficient and the expansion coefficient of each material constituting the expansion compensation mortar.

[0010] As a further improvement of the present application, in step 1, the calculation method of the theoretical expansion coefficient is as follows: The expansion volume Vp required by the expansion compensation clay layer = the expansion space Vk generated by the linear expansion of the steel shell to the expansion (contraction) of the inner diameter - the expansion volume Vs generated by the linear expansion of the acid-resistant layer - the expansion space Vm generated by the linear expansion of the wear-resistant layer to the expansion (contraction) of the outer diameter; Clay expansion coefficient = clay expansion volume Vp / total volume V before clay expansion.

[0011] As a further improvement of the present application, in step 2, the engineering expansion coefficient is 1% to 20% greater than the theoretical expansion coefficient.

[0012] As a further improvement of the present application, in step 3, the calculation formula for the proportion of each material in the expansion compensation mortar formula is as follows: Engineering expansion coefficient × total volume V = main material volume Vz × main material expansion coefficient + auxiliary material 1 volume Va × auxiliary material 1 expansion coefficient + auxiliary material 2 volume Vb × auxiliary material 2 expansion coefficient + … + auxiliary material n volume Vn × auxiliary material n expansion coefficient.

[0013] The present application also provides an application of expansion compensation mortar, wherein the expansion compensation mortar is used to fill between every two layers of materials for dispersed compensation, or the expansion compensation mortar is used to concentrate between two layers of materials for concentrated compensation.

[0014] Beneficial effect: The present application uses expansion compensation mortar with a settable expansion coefficient to fill between the lining layers of the outer wall of the equipment, which can ensure the continuous stability of the outer wall structure at various temperatures, so that the service life of the equipment is not affected when the steel shell is insulated. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the shell wall structure; In the figure: 1-insulation layer, 2-steel shell, 3-acid and alkali resistant protective layer, 4-expansion compensation mortar and filling gap, 5-wear-resistant protective layer. DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0017] The present invention provides an expansion compensation mortar, wherein the expansion compensation mortar is prepared by mixing polytetrafluoroethylene powder with a large expansion coefficient as a main material and at least one powder with a small expansion coefficient as an auxiliary material, wherein the auxiliary materials with a small expansion coefficient are: KPI powder, graphite powder, silicon carbide powder, and corundum powder; wherein: The proportion of polytetrafluoroethylene powder is 1%~99%; the proportion of KPI powder is 0~90%; the proportion of graphite powder is 0~90%; the proportion of silicon carbide powder is 0~50%; the proportion of corundum powder is 0~50%; the binder of the expansion compensation mortar is water glass or asphalt or acid-resistant resin.

[0018] Preferably, the expansion compensation mortar formula used in an acidic environment is: polytetrafluoroethylene powder + KPI powder + silicon carbide powder or corundum powder, with water glass or acid-resistant resin as a binder.

[0019] Preferably, the expansion compensation mortar used in alkaline or acid-base alternating environments has a formula of polytetrafluoroethylene powder + graphite powder + corundum powder, with asphalt as a binder.

[0020] The present invention also discloses a method for preparing the expansion compensation mortar, the steps of which are as follows: Step 1: Calculate the theoretical expansion coefficient required for the expansion compensation mortar according to the designed expansion compensation layer thickness; Step 2: Determine the engineering expansion coefficient based on the theoretical expansion coefficient calculated in step 1; Step 3: Calculate the proportion of each material based on the determined engineering expansion coefficient and the expansion coefficient of each material constituting the expansion compensation mortar.

[0021] Preferably, in step 1, the calculation method of the theoretical expansion coefficient is as follows: The expansion volume Vp required by the expansion compensation clay layer = the expansion space Vk generated by the linear expansion of the steel shell to the expansion (contraction) of the inner diameter - the expansion volume Vs generated by the linear expansion of the acid-resistant layer - the expansion space Vm generated by the linear expansion of the wear-resistant layer to the expansion (contraction) of the outer diameter; Clay expansion coefficient = clay expansion volume Vp / total volume V before clay expansion.

[0022] Preferably, in step 2, the engineering expansion coefficient is 1% to 20% greater than the theoretical expansion coefficient.

[0023] Preferably, in step 3, the calculation formula for the proportion of each material in the expansion compensation mortar formula is as follows: Engineering expansion coefficient × total volume V = main material volume Vz × main material expansion coefficient + auxiliary material 1 volume Va × auxiliary material 1 expansion coefficient + auxiliary material 2 volume Vb × auxiliary material 2 expansion coefficient + … + auxiliary material n volume Vn × auxiliary material n expansion coefficient.

[0024] The expansion compensation mortar of the present invention is used to fill between every two layers of materials for dispersed compensation, or the expansion compensation mortar is used to concentrate between two layers of materials for concentrated compensation. Example 1

[0025] The implementation object of this product and technology: the kettle wall manufacturing of the horizontal reactor of hydrochloric acid working condition; among which, the specific parameters of the horizontal reactor are as follows: (1) Slurry in the kettle: ① Hydrochloric acid: 31%; ②Solid content: 300g% L; ③ Temperature: 150℃; ④Pressure: 0.6MPa; (2) Kettle structure ① Length 16000 mm; ②Outer diameter 2266 mm; ③Inner diameter 2000 mm; (3) Kettle wall structure It adopts a five-layer composite structure of thermal insulation layer + steel shell + acid-resistant protective layer + expansion compensation layer + wear-resistant layer. The working temperature of the steel shell is set to 135℃; among which: ①Insulation layer: 150mm insulation fiber; ②Steel shell: 20mm heat-resistant steel; ③Acid-resistant protective layer: 3mm polytetrafluoroethylene sheet; ④Filling layer: 45mm acid-resistant expansion compensation mortar; ⑤ Wear-resistant layer: 65 mm custom silicon carbide bricks; (4) Acid-resistant expansion compensation mortar ① Made of polytetrafluoroethylene powder + KPI powder + silicon carbide powder bonded with water glass; ②The theoretical expansion coefficient of acid-resistant expansion compensation mortar is 9.96×10 -6 / ℃, the specific calculation method is as follows: at a working temperature of 150°C, the steel shell under the 150 mm insulation layer is calculated at an average temperature of 135°C. The expansion of the steel shell at 135°C increases the inner diameter of the steel shell by about 3.09mm; the volume expansion of the polytetrafluoroethylene acid-resistant layer is greater than the volume expansion of the steel shell, and its inner diameter increases by about 2.42mm at 135°C; the expansion of the silicon carbide brick at 150°C increases the outer diameter of the wear-resistant lining by about 1.93mm; therefore, at this temperature (average of about 140°C), the thickness of the 45mm expansion compensation clay layer should be increased by 0.49mm to ensure that the outer diameter of the clay layer is in gapless contact with the inner diameter of the polytetrafluoroethylene layer, and at the same time, the inner diameter of the clay layer is in gapless contact with the outer diameter of the silicon carbide layer, thereby ensuring the continuity and stability of the kettle wall lining structure and avoiding the wear-resistant lining layer from sinking due to the outward expansion of the steel shell due to heat, resulting in structural damage; in this way, according to the principle of complete volume compensation, the 45 The expansion coefficient of the cement layer should be designed to be 9.96×10 -6 / ℃; the engineering expansion coefficient is 10.44% greater than the theoretical expansion coefficient, and the value is 11×10 -6 / ℃; ③The material ratio of expansion compensation mortar is: Polytetrafluoroethylene material: 8.9%, KPI powder: 81.1%, Silicon carbide powder: 10%, The amount of water glass added is 10%~30% of the total weight of the expansion compensation cement powder; (5) Filling of expansion compensation mortar Using a centralized compensation method, the expansion compensation clay powder is mixed with 10% of its total weight of water glass to form a semi-dry clay material, which is uniformly filled in the gap formed by the tetrafluoro acid-resistant layer and the silicon carbide wear-resistant layer and compacted. Example 2

[0026] The product is applied to vertical reactors with alternating acid-base working conditions, first acid and then alkali, and its working conditions are: Sulfuric acid: 50% industrial sulphuric acid; Alkali: industrial grade sodium hydroxide, alkali concentration 15% Operating temperature: 150°C Working pressure: 0.3Mpa 1. Kettle structure 1. Outer diameter: 2266 mm 2. Inner diameter: 2000 mm 3. Height: 20000mm 2. Kettle wall structure 1. Steel shell: 20 mm heat-resistant steel 2. Acid-resistant layer: 3 mm polytetrafluoroethylene sheet lining 3. Filling layer: 45mm acid and alkali resistant expansion compensation mortar 4. Wear-resistant layer: 65 mm customized graphite brick 5. Insulation layer: 150 mm insulation fiber 3. Acid and alkali resistant expansion compensation mortar 1. Clay formula ① Polytetrafluoroethylene powder ②Graphite powder ③Corundum powder ④ Modified asphalt used as a binder 2. Determination of expansion coefficient ①、Set the working temperature of the steel shell after insulation: 135°C ②、Theoretical expansion coefficient: 9.96×10 -6 / ℃ The calculation method is the same as that in Example 1; ③、Engineering expansion coefficient According to experimental determination, the engineering expansion coefficient is selected as 11.8×10 -6 / ℃, the compensation effect is best; ④. Clay ratio: Polytetrafluoroethylene powder: 6.8% Graphite powder: 83.2% Corundum powder: 10%; 3. The amount of asphalt added is 25%-35% of the total weight of the cement; 4. Filling of expansion compensation mortar The expansion compensation mortar is concentratedly filled in the gap between the polytetrafluoroethylene acid-resistant layer and the graphite wear-resistant layer for centralized compensation.

[0027] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An expansion compensation mortar, characterized in that: The expansion compensation mortar is made of polytetrafluoroethylene or its modified material with a large expansion coefficient as the main material, and at least one powder with a small expansion coefficient as the auxiliary material, and the auxiliary materials with a small expansion coefficient are: KPI powder, graphite powder, silicon carbide powder, corundum powder; wherein, Polytetrafluoroethylene or its modified materials account for 1%~99%; KPI powder accounts for 0~90%; graphite powder accounts for 0~90%; silicon carbide powder accounts for 0~50%; corundum powder accounts for 0~50%.

2. The expansion compensation mortar according to claim 1, characterized in that: The binder of the expansion compensation mortar is water glass or asphalt or acid-resistant resin.

3. The expansion compensation mortar according to claim 2, characterized in that: The formula of expansion compensation mortar used in acidic environment is: polytetrafluoroethylene or its modified material + KPI powder + silicon carbide powder or corundum powder, with water glass or acid-resistant resin as binder.

4. The expansion compensation mortar according to claim 2, characterized in that: The formula of expansion compensation mortar used in alkaline or acid-base alternating environment is: polytetrafluoroethylene or its modified material + graphite powder + corundum powder, with asphalt as binder.

5. A method for preparing an expansion compensation mortar according to any one of claims 1 to 4, characterized in that: Here are the steps: Step 1: Calculate the theoretical expansion coefficient required for the expansion compensation mortar according to the designed expansion compensation layer thickness; Step 2: Determine the engineering expansion coefficient based on the theoretical expansion coefficient calculated in step 1; Step 3: Calculate the proportion of each material based on the determined engineering expansion coefficient and the expansion coefficient of each material constituting the expansion compensation mortar.

6. The method for preparing the expansion compensation mortar according to claim 5, characterized in that: In step 1, the theoretical expansion coefficient is calculated as follows: The expansion volume Vp required by the expansion compensation clay layer = the expansion space Vk generated by the linear expansion of the steel shell to the expansion (contraction) of the inner diameter - the expansion volume Vs generated by the linear expansion of the acid-resistant layer - the expansion space Vm generated by the linear expansion of the wear-resistant layer to the expansion (contraction) of the outer diameter; Clay expansion coefficient = clay expansion volume Vp / total volume V before clay expansion.

7. The method for preparing the expansion compensation mortar according to claim 5, characterized in that: In step 2, the engineering expansion coefficient is 1% to 20% greater than the theoretical expansion coefficient.

8. The method for preparing the expansion compensation mortar according to claim 5, characterized in that: In step 3, the calculation formula for the proportion of each material in the expansion compensation mortar formula is as follows: Engineering expansion coefficient × total volume V = main material volume Vz × main material expansion coefficient + auxiliary material 1 volume Va × auxiliary material 1 expansion coefficient + auxiliary material 2 volume Vb × auxiliary material 2 expansion coefficient + … + auxiliary material n volume Vn × auxiliary material n expansion coefficient.

9. An application of the expansion compensation mortar according to any one of claims 1 to 4, characterized in that: The expansion compensation mortar is used to fill between every two layers of materials for dispersed compensation, or the expansion compensation mortar is used to concentrate between two layers of materials for concentrated compensation.

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