Thermal insulation and heat preservation method for lower groove short pipe of RH refining furnace

Abstract

The embodiment of the invention provides a thermal insulation and heat preservation method for a lower groove short pipe of an RH refining furnace. The thermal insulation and heat preservation method comprises the steps that adherends on the inner wall of a steel shell of the lower groove short pipe are cleaned and polished; the inner wall of the steel shell is coated with the heat insulation and heat preservation coating for the lower groove short pipe of the RH refining furnace, a heat insulation and heat preservation layer is formed after room-temperature drying, and the thickness of the heat insulation and heat preservation layer is 1-3 mm; refractory bricks are built along the inner wall of the heat insulation layer to form a cylindrical working layer; castable is injected between the working layer and the heat insulation layer for gap filling, and a filler layer is formed.

Description

Technical Field

[0001] This invention relates to the field of RH refining furnace technology, and in particular to a method for heat insulation of the short tube in the lower tank of an RH refining furnace. Background Technology

[0002] The RH refining furnace is a crucial metallurgical equipment for ladle refining. It performs metallurgical functions such as decarburization, deoxidation, removal of harmful gases (H2, N2) and inclusions, and control of steel composition and temperature. It is widely used in the production of high-end products such as automotive steel, silicon steel, pipeline steel, and bearing steel. With prolonged processing time in the RH refining furnace, the heat radiation and conduction of the molten steel cause the temperature of the lower trough short tubes and the bottom steel shell to continuously rise, frequently resulting in red-hot steel shells or furnace shell deformation. This significantly impacts the service life of the RH refining furnace and furnace management. Currently, RH refining furnaces typically only use standardized insulation products (such as calcium silicate boards), insulating castables, or refractory fibers on the lower trough sidewalls, while lacking effective insulation measures for the lower trough short tubes.

[0003] Patent document CN 220454343 U discloses "A device for preventing deformation of the short tube of a vacuum tank trouser leg". This device mainly uses compressed air blown out by an external air compressor to cool the steel shell, but it has problems such as complex equipment installation and maintenance. Patent document CN 218507829 U discloses "A heat insulation device for preventing deformation of the bottom tank shell". This device is composed of metal support partitions, nanofiber boards, anchors, and castable heat insulation layers. It constructs a heat insulation structure through the composite of shaped heat insulation material and metal support. However, it has problems such as the shaped heat insulation material being prone to powdering after long-term use and the metal support not being resistant to high temperatures. In addition, the design and construction of this device are relatively complex, the installation time is long, and it cannot achieve rapid maintenance and online operation of RH refining furnaces. Patent document CN 219861435 U discloses "A new type of heat insulation plate for the lower tank of an RH furnace". This novel insulation board provides an insulation structure composed of metal parts and fiber modules. While the fiber modules can provide good insulation in the short term, long-term use in high-temperature environments accelerates the development of crystals within the modules, causing the fiber structure to gradually break, reducing porosity, and resulting in poorer insulation or even pulverization. Furthermore, the structure of this novel insulation board is relatively complex, and the installation period is long. Patent document CN 212174981 U discloses "A Lining Structure for the Lower Tank of an RH Vacuum Degassing Device." This lining structure mainly consists of an insulation layer, a permanent layer, and a working layer in the horizontal direction of the lower tank. It lacks insulation for the steel shell at the short pipe of the lower tank, and the calcium silicate insulation board used in the insulation layer is prone to pulverization over time.

[0004] In the process of developing this invention, the applicant discovered at least the following problems in the prior art:

[0005] The lower groove short pipe without an insulation lining structure is prone to overheating and deformation, while traditional insulation materials cannot meet the requirements of small thickness, good insulation effect and convenient construction. Summary of the Invention

[0006] This invention provides a method for heat insulation of the lower trough short pipe of an RH refining furnace, which solves the problems that the lower trough short pipe without heat insulation lining is prone to overheating and deformation, while traditional heat insulation materials cannot meet the requirements of small thickness, good heat insulation effect and convenient construction.

[0007] To achieve the above objectives, in a first aspect, embodiments of the present invention provide a method for heat insulation of the short tube in the lower tank of an RH refining furnace, comprising:

[0008] Clean and grind the adhering substances on the inner wall of the lower groove short pipe steel shell;

[0009] The short tubes of the lower trough of the RH refining furnace are coated with heat-insulating paint onto the inner wall of the steel shell. After drying at room temperature, a heat-insulating layer is formed. The thickness of the heat-insulating layer is 1 to 3 mm.

[0010] Refractory bricks are laid along the inner wall of the heat insulation layer to form a cylindrical working layer;

[0011] A filler layer is formed by injecting castable refractory between the working layer and the thermal insulation layer.

[0012] The lower trough short pipe of the RH refining furnace includes: a cylindrical steel shell, a heat insulation layer disposed on the inner wall of the steel shell, and a cylindrical working layer disposed on the inner side of the heat insulation layer; the working layer is used to directly contact the molten steel and provide the molten steel with a high-temperature resistant and erosion-resistant pipe; the heat insulation layer is formed by applying heat insulation coating.

[0013] Furthermore, the components of the heat-insulating coating include: binder, refractory powder, functional filler, additives, and water.

[0014] Furthermore, the binder accounts for 36% to 50%, and the binder includes one or more of silica sol, aluminum sol, aluminum dihydrogen phosphate, and water glass.

[0015] Furthermore, the refractory powder accounts for 8% to 20%, and the refractory powder includes one or more of alumina micro powder, magnesium aluminum spinel micro powder, and mullite micro powder.

[0016] Furthermore, the functional filler accounts for 23% to 35% of the total content, and the functional filler includes one or more of mica powder, hollow glass microspheres, hollow ceramic microspheres, cenospheres, and titanium dioxide; the additive accounts for 1% to 3% of the total content, and the functional filler includes dispersants and / or explosion-proof agents.

[0017] The water addition is 18% to 30%.

[0018] Furthermore, the binder accounts for 48%, specifically including alumina sol; the refractory powder accounts for 8%, including alumina micro powder and / or magnesium aluminum spinel micro powder; the functional filler accounts for 24%, specifically including hollow ceramic microspheres, mica powder and / or cenospheres; the additives account for 1.5%, specifically including dispersants and explosion-proof agents; and the moisture content accounts for 18.5%.

[0019] Furthermore, the binder accounts for 38%, specifically including water glass; the refractory powder accounts for 9%, specifically including alumina micro powder and / or mullite micro powder; the functional filler accounts for 27%, specifically including mica powder, titanium dioxide and / or cenospheres; the additives account for 1%, specifically including dispersants and explosion-proof agents; and the moisture content accounts for 25%.

[0020] Furthermore, the heat insulation method for the short pipe in the lower part of the RH refining furnace is specifically as follows:

[0021] Clean and grind the adhering substances on the inner wall of the lower groove short pipe steel shell;

[0022] Weigh the binder, refractory powder, functional filler and additives in a preset ratio using an electronic scale, add water and stir evenly to form a heat insulation coating.

[0023] Apply the heat insulation coating to the inner surface of the lower short pipe steel shell with a brush. The coating thickness is 3 mm. After drying at room temperature, a heat insulation layer is formed. The thickness of the heat insulation layer (3) is 3 mm.

[0024] Refractory bricks are laid along the inner wall of the heat insulation layer to form a cylindrical working layer;

[0025] A filler layer is formed by injecting castable refractory between the working layer and the thermal insulation layer.

[0026] The thermal insulation coating comprises the following components: 39% binder, specifically 39% water glass; 10% refractory powder, specifically 7% alumina micropowder and 3% magnesium aluminum spinel micropowder; 27% functional fillers, specifically 5% hollow glass microspheres, 7% titanium dioxide, 7% mica powder and 8% cenospheres; 1.2% additives, specifically 0.2% dispersant and 1% explosion-proof agent; and 22.8% moisture. The dispersant is sodium tripolyphosphate, and the explosion-proof agent is explosion-proof fiber.

[0027] Secondly, embodiments of the present invention provide a short pipe for the lower trough of an RH refining furnace, comprising: a cylindrical steel shell, a heat insulation layer disposed on the inner wall of the steel shell, and a cylindrical working layer disposed on the inner side of the heat insulation layer; the working layer is used to directly contact molten steel and provide a high-temperature resistant and erosion-resistant pipe for the molten steel; the heat insulation layer is formed by applying a heat insulation coating.

[0028] Furthermore, the thickness of the heat insulation layer is 1 to 3 millimeters.

[0029] Furthermore, the components of the heat-insulating coating include: binder, refractory powder, functional filler, additives, and water.

[0030] Furthermore, the binder accounts for 36% to 50%, and the binder includes one or more of silica sol, aluminum sol, aluminum dihydrogen phosphate, and water glass.

[0031] Furthermore, the refractory powder accounts for 8% to 20%, and the refractory powder includes one or more of alumina micro powder, magnesium aluminum spinel micro powder, and mullite micro powder.

[0032] Furthermore, the functional filler accounts for 23% to 35% of the total content, and the functional filler includes one or more of mica powder, hollow glass microspheres, hollow ceramic microspheres, cenospheres, and titanium dioxide; the additive accounts for 1% to 3% of the total content, and the functional filler includes dispersants and / or explosion-proof agents.

[0033] The water addition is 18% to 30%.

[0034] Thirdly, embodiments of the present invention provide a heat-insulating coating for the short pipe of the lower tank of an RH refining furnace, wherein the components of the heat-insulating coating include: binder, refractory powder, functional filler, additives and water;

[0035] The binder accounts for 36% to 50%, and the binder includes one or more of silica sol, aluminum sol, aluminum dihydrogen phosphate, and water glass;

[0036] The refractory powder accounts for 8% to 20%, and the refractory powder includes one or more of alumina micro powder, magnesium aluminum spinel micro powder, and mullite micro powder.

[0037] The functional filler comprises 23% to 35% of the total content, and includes one or more of mica powder, hollow glass microspheres, hollow ceramic microspheres, cenospheres, and titanium dioxide; the additive comprises 1% to 3% of the total content, and includes dispersants and / or explosion-proof agents.

[0038] The water addition is 18% to 30%.

[0039] Furthermore, the binder accounts for 48%, specifically including alumina sol; the refractory powder accounts for 8%, including alumina micro powder and / or magnesium aluminum spinel micro powder; the functional filler accounts for 24%, specifically including hollow ceramic microspheres, mica powder and / or cenospheres; the additives account for 1.5%, specifically including dispersants and explosion-proof agents; and the moisture content accounts for 18.5%.

[0040] Furthermore, the binder accounts for 38%, specifically including water glass; the refractory powder accounts for 9%, specifically including alumina micro powder and / or mullite micro powder; the functional filler accounts for 27%, specifically including mica powder, titanium dioxide and / or cenospheres; the additives account for 1%, specifically including dispersants and explosion-proof agents; and the moisture content accounts for 25%.

[0041] The above technical solution has the following beneficial effects: By applying heat insulation material to the inner surface of the steel shell of the lower trough short tube, a heat insulation layer is set, thereby reducing the rate at which heat is transferred from the working layer to the steel shell, thus reducing the rate at which the steel shell temperature rises. Compared with the case without heat insulation material, the temperature of the steel shell is lower under the same heat cycle, and the lower trough short tube is less prone to overheating and deformation, thereby ensuring production safety, extending the service life of the lower trough short tube, allowing the same RH refining furnace equipment to operate for more heat cycles, reducing production costs, and improving production efficiency. Attached Figure Description

[0042] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0043] Figure 1 This is a flowchart of a heat insulation method for the short tube in the lower tank of an RH refining furnace, one of the embodiments of the present invention;

[0044] Figure 2 This is a schematic diagram of the structure of a short tube in the lower trough of an RH refining furnace, one of the embodiments of the present invention;

[0045] Figure 3 This is another structural schematic diagram of a short tube in the lower part of an RH refining furnace, which is one of the embodiments of the present invention.

[0046] The reference numerals in the attached diagram are: 1. Lower trench short pipe; 2. Steel shell; 3. Thermal insulation layer; 4. Working layer; 5. Filler layer. Detailed Implementation

[0047] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention.

[0048] The inventors discovered that in existing technologies, thick insulation boards and other materials are typically used for heat insulation in RH refining furnaces. However, due to the small diameter of the lower trough short pipes in RH refining furnaces (for example, some lower trough short pipes have a height of 295 mm, an inner diameter of the steel shell of the lower trough short pipe of 840 mm, and a pipe diameter of 550 mm at the center of the working layer), it is difficult to construct thick insulation boards. This results in higher temperatures inside the steel shell of the lower trough short pipes (trouser leg short pipes) and at the bottom of the lower trough. If insulation boards are installed, in order to keep the pipe diameter at the center of the working layer from decreasing significantly, the thickness of the working layer will be affected, thus limiting the lifespan of the RH refining furnace. If the working layer thickness is kept constant and insulation boards are added, the pipe diameter at the center of the working layer will be reduced, thereby reducing the steel flow rate of the RH refining furnace and lowering its processing efficiency. The lower trough short pipe without an insulating lining is prone to overheating and deformation. The limited space in the lower trough short pipe makes it difficult to construct shaped refractory bricks or pour insulating castables, which can reduce the molten steel flow rate in the RH refining furnace and decrease its processing efficiency. Existing technologies mainly suppress heat radiation from the molten steel in the ladle by adding cooling devices to the outside of the steel shell, or by adding shaped insulating bricks or fiber cotton to the bottom of the lower trough to suppress heat conduction of the molten steel inside the shell. However, they lack insulation treatment for the steel shell at the lower trough short pipe. The lower trough short pipe has a circular steel shell structure and limited space; if shaped insulating bricks are added, the brick shape must be designed with an arc. Furthermore, if the shaped insulating bricks are too thick, it will affect the molten steel flow rate (a certain thickness of the working layer is needed to ensure its service life, which can only reduce the molten steel flow rate in vacuum processing), while if they are too thin, they are insufficient for insulation. Therefore, the insulation material at the lower trough short pipe needs to be thin, have good insulation performance, and be easy to construct, which is generally difficult to achieve with existing technologies.

[0049] This invention introduces a convenient, thin, and effective insulation lining structure into the steel shell area of ​​the lower trough short pipe of an RH refining furnace. This improves the insulation effect of this area, reduces heat loss from the RH refining furnace, and ensures smooth operation of the RH refining furnace. Traditionally, most heat-insulating coatings are used in low-temperature environments (100-200℃). The inventors have creatively introduced this heat-insulating coating into the insulation layer of RH refining furnaces in the steel metallurgical field, specifically in the lower trough short pipe area, where the inner wall temperature of the steel shell is approximately 600-700℃. Furthermore, the binders used are all inorganic binders, widely available, with good high-temperature stability, low cost, and more environmentally friendly than organic binders. Refractory powder is also incorporated into the coating to improve its high-temperature resistance and mechanical strength. The coating of this invention is easy to apply, has a thin layer, and does not affect the steel flow rate during RH furnace operation.

[0050] First, as Figure 1 As shown, this embodiment of the invention provides a method for heat insulation of the short tube in the lower tank of an RH refining furnace, comprising:

[0051] Step S10: Clean and polish the adhering material on the inner wall of the lower groove short pipe steel shell 2.

[0052] Step S11: Apply heat-insulating coating to the inner wall of the steel shell 2 of the short tube of the lower tank of the RH refining furnace. After drying at room temperature, heat-insulating layer 3 is formed. The thickness of heat-insulating layer 3 is 1 to 3 mm.

[0053] Step S12: Along the inner wall of the heat insulation layer 3, refractory bricks are laid to form a cylindrical working layer 4;

[0054] Step S13: Inject castable refractory between the working layer 4 and the heat insulation layer 3 to fill the gap, forming the filler layer 5;

[0055] The lower trough short pipe 1 of the RH refining furnace includes: a cylindrical steel shell 2, a heat insulation layer 3 disposed on the inner wall of the steel shell, and a cylindrical working layer 4 disposed on the inner side of the heat insulation layer; the working layer is used to directly contact the molten steel and provide the molten steel with a high-temperature resistant and erosion-resistant pipe; the heat insulation layer is formed by applying heat insulation coating.

[0056] The embodiments of the present invention have the following technical effects: By applying heat insulation material to the inner surface of the steel shell of the lower groove short tube, a heat insulation layer is set, which reduces the rate at which heat is transferred from the working layer to the steel shell, thereby reducing the rate at which the steel shell temperature rises. Compared with the case without heat insulation material, the temperature of the steel shell is lower under the same furnace cycle, and the lower groove short tube is less prone to overheating deformation, thus ensuring production safety, extending the service life of the lower groove short tube, allowing the same RH refining furnace equipment to operate for more furnace cycles, reducing production costs, and improving production efficiency.

[0057] Furthermore, the components of the heat-insulating coating include: binder, refractory powder, functional filler, additives, and water.

[0058] Furthermore, the binder accounts for 36% to 50%, and the binder includes one or more of silica sol, aluminum sol, aluminum dihydrogen phosphate, and water glass.

[0059] Furthermore, the refractory powder accounts for 8% to 20%, and the refractory powder includes one or more of alumina micro powder, magnesium aluminum spinel micro powder, and mullite micro powder.

[0060] Furthermore, the functional filler accounts for 23% to 35% of the total content, and the functional filler includes one or more of mica powder, hollow glass microspheres, hollow ceramic microspheres, cenospheres, and titanium dioxide; the additive accounts for 1% to 3% of the total content, and the functional filler includes dispersants and / or explosion-proof agents.

[0061] The water addition is 18% to 30%.

[0062] Furthermore, the binder accounts for 48%, specifically including alumina sol; the refractory powder accounts for 8%, including alumina micro powder and / or magnesium aluminum spinel micro powder; the functional filler accounts for 24%, specifically including hollow ceramic microspheres, mica powder and / or cenospheres; the additives account for 1.5%, specifically including dispersants and explosion-proof agents; and the moisture content accounts for 18.5%.

[0063] Furthermore, the binder accounts for 38%, specifically including water glass; the refractory powder accounts for 9%, specifically including alumina micro powder and / or mullite micro powder; the functional filler accounts for 27%, specifically including mica powder, titanium dioxide and / or cenospheres; the additives account for 1%, specifically including dispersants and explosion-proof agents; and the moisture content accounts for 25%.

[0064] Furthermore, the heat insulation method for the short pipe in the lower part of the RH refining furnace is specifically as follows:

[0065] Clean and grind the adhering substances on the inner wall of the lower groove short pipe steel shell;

[0066] Weigh the binder, refractory powder, functional filler and additives in a preset ratio using an electronic scale, add water and stir evenly to form a heat insulation coating.

[0067] Apply the heat insulation coating to the inner surface of the lower short pipe steel shell with a brush. The coating thickness is 3 mm. After drying at room temperature, a heat insulation layer is formed. The thickness of the heat insulation layer (3) is 3 mm.

[0068] Refractory bricks are laid along the inner wall of the heat insulation layer to form a cylindrical working layer;

[0069] A filler layer is formed by injecting castable refractory between the working layer and the thermal insulation layer.

[0070] The thermal insulation coating comprises the following components: 39% binder, specifically 39% water glass; 10% refractory powder, specifically 7% alumina micropowder and 3% magnesium aluminum spinel micropowder; 27% functional filler, specifically 5% hollow glass microspheres, 7% titanium dioxide, 7% mica powder and 8% cenospheres; 1.2% additives, specifically 0.2% dispersant and 1% explosion-proof agent; and 22.8% moisture. The percentages of the components in the thermal insulation coating in this embodiment are percentages based on the overall coating composition. Specifically, the dispersant is sodium tripolyphosphate, and the explosion-proof agent is explosion-proof fiber.

[0071] Laboratory thermal insulation test: The thermal insulation coating was applied to the steel shell and placed at the door of a high-temperature furnace (temperature set at 800℃) for 10 minutes. The surface of the steel plate without coating heated up rapidly and turned black, with the final temperature fluctuating in the range of 520-570℃. The steel plate with coating heated up slowly, with the final temperature fluctuating in the range of 370-420℃. Therefore, the thermal insulation coating can reduce the temperature by about 150℃.

[0072] RH furnace on-site temperature testing: On-site temperature tests were conducted on the lower tank short pipe shells of RH furnaces with and without thermal insulation layers. Some temperature deviations were negative, considered measurement errors; consecutive negative temperature deviations were considered to indicate the thermal insulation layer had failed. Secondly, due to on-site measurement limitations, some furnace runs only recorded temperatures for steel shells with or without thermal insulation coatings; therefore, data that could not provide a direct comparison were discarded. Furthermore, since industrial trials cannot guarantee consistency in steel grades and operating conditions between the two RH refining furnaces, some furnace runs with significant negative temperature deviations were considered to be related to longer vacuum treatment times for molten steel (RH furnaces with thermal insulation layers generally have longer vacuum treatment times for steel grades). Table 1 shows the temperature measurement data for steel shells with and without thermal insulation layers. The data shows that the temperature of the steel shells with thermal insulation layers was below 300℃ for the first 10 furnaces, and the average temperature was approximately 53℃ lower than that without thermal insulation layers. The maximum temperature deviation was 155℃, and the effective thermal insulation effect was observed in 63 furnaces. (Subsequent furnaces showing consecutive negative deviations are considered to have lost their thermal insulation effect.)

[0073]

[0074]

[0075] Table 1. Temperature comparison of steel shells with and without thermal insulation layer (3mm).

[0076] The embodiments of this invention have the following technical effects: The red-hot deformation of the steel shell of the lower trough short tube in an RH refining furnace is mainly affected by two factors: 1. Continuous heat conduction from the inside to the outside by the molten steel undergoing vacuum treatment inside; 2. Direct heat radiation from the molten steel in the ladle to the steel shell when the immersion tube is inserted into the ladle. Applying heat-insulating coating to the inner wall of the lower trough short tube alone cannot completely solve the problem of the steel shell red-hot. However, compared to the lower trough short tube without coating, applying heat-insulating coating has the following advantages: 1. It can effectively reduce the occurrence of "grooving" at the junction of the internal circulation tube and the immersion tube caused by long-term thermal stress on the steel shell. According to on-site tracking and comparison data, the "grooving" phenomenon after applying heat insulation coating has changed from appearing after 30-40 heats to appearing after 70-80 heats. This greatly reduces the amount of maintenance material used inside the insertion tube, reduces the introduction of inclusions, and helps in the production of clean steel. 2. It helps to delay the deformation caused by high steel shell temperature, reduces the steel shell maintenance cycle (from the original three major overhaul cycles to about four major overhaul cycles), increases the effective utilization rate of steel shells by 10-25%, and reduces the difficulty of equipment maintenance.

[0077] Secondly, such as Figure 2 As shown, an embodiment of the present invention provides a short pipe 1 for the lower trough of an RH refining furnace, comprising: a cylindrical steel shell 2, a heat insulation layer 3 disposed on the inner wall of the steel shell, and a cylindrical working layer 4 disposed on the inner side of the heat insulation layer; the working layer 4 is used to directly contact molten steel and provide a high-temperature resistant and erosion-resistant pipe for the molten steel; the heat insulation layer 3 is formed by coating with heat insulation paint.

[0078] Preferably, such as Figure 3 As shown, a filler layer 5 is provided between the working layer 4 and the heat insulation layer 3.

[0079] The steel shell 2 serves as the outer shell of the lower trough short pipe 1 of the RH refining furnace. The heat insulation layer 3 is a thin layer of heat insulation formed by applying heat insulation coating to the inner surface of the steel shell 2. The thickness of the heat insulation layer 3 is significantly less than that of the working layer 4. The working layer 4 is formed by stacking high-temperature refractory bricks along the inner side of the steel shell 2, forming a circular pipe in the center for the flow of molten steel. The inner surface of the working layer 4 is in direct contact with the molten steel. Since the working layer 4 itself does not have heat insulation function, and the lower trough short pipe in the traditional method does not have a heat insulation layer 3, heat is more easily transferred to the steel shell 2, causing the steel shell 2 to be more prone to red-hot deformation and safety hazards. In this embodiment of the invention, the heat insulation layer 3 reduces the rate of heat transfer to the steel shell 2, thereby reducing the rate of temperature rise of the steel shell 2. The filler layer 5 fills the gaps inside the working layer 4 and the gaps between the working layer 4 and the heat insulation layer 3 to prevent molten steel from seeping in. Preferably, the high-temperature refractory bricks of the working layer include: magnesia spinel bricks. Preferably, the filler of the filler layer 5 includes: corundum spinel castable or corundum castable.

[0080] The embodiments of the present invention have the following technical effects: By applying heat insulation material to the inner surface of the lower trough short tube steel shell, a heat insulation layer is set, thereby reducing the rate at which heat is transferred from the working layer to the steel shell, thus reducing the rate at which the steel shell temperature rises. Compared with the case without heat insulation material, the steel shell temperature is lower under the same furnace cycle, and the lower trough short tube is less prone to overheating deformation, thereby ensuring production safety, extending the service life of the lower trough short tube, allowing the same RH refining furnace equipment to operate for more furnace cycles, reducing production costs, and improving production efficiency.

[0081] Furthermore, the thickness of the heat insulation layer 3 is 1 to 3 millimeters.

[0082] The thickness of the thermal insulation layer 3 is between 1 and 3 millimeters. If it is too thin, it will not provide good thermal insulation. Traditional thermal insulation boards are usually thicker, which will reduce the diameter of the molten steel pipe in the center of the working layer and easily reduce the molten steel flow rate of the RH refining furnace. In this embodiment, the thickness of the thermal insulation layer is between 1 and 3 millimeters, which provides good thermal insulation without affecting the molten steel flow rate during vacuum treatment.

[0083] Furthermore, the components of the heat-insulating coating include: binder, refractory powder, functional filler, additives, and water.

[0084] The binder serves to bond the various components of the coating together, forming a dense coating layer. The refractory powder enhances the coating's high-temperature resistance and mechanical strength due to its good high-temperature volume stability and excellent thermal shock resistance. The functional filler reduces the coating's thermal conductivity, improving its insulation effect, while also enhancing its mechanical strength and adhesion, thus improving its application properties. The additives effectively improve the coating's dispersibility, flowability, and stability, ensuring its application performance.

[0085] Furthermore, the binder accounts for 36% to 50%, and the binder includes one or more of silica sol, aluminum sol, aluminum dihydrogen phosphate, and water glass.

[0086] The binder has excellent high-temperature resistance and bonding strength, low corrosivity to steel shells, and produces no gas during use, making it environmentally friendly.

[0087] Furthermore, the refractory powder accounts for 8% to 20% of the total content, and the refractory powder includes one or more of alumina micro powder, magnesium aluminum spinel micro powder, and mullite micro powder. It is compatible with the permanent layer (working layer and filler layer) material, and the refractory powder for coatings has a similar composition to the refractory powder for joint filler castables, making it easier to form a cohesive whole.

[0088] Furthermore, the functional filler accounts for 23% to 35% of the total content, and the functional filler includes one or more of mica powder, hollow glass microspheres, hollow ceramic microspheres, cenospheres, and titanium dioxide; the additive accounts for 1% to 3% of the total content, and the functional filler includes dispersants and / or explosion-proof agents; the functional filler has a low thermal conductivity, excellent weather resistance, high mechanical strength, and adhesion.

[0089] The water addition is 18% to 30%.

[0090] Thirdly, embodiments of the present invention provide a heat-insulating coating for the short pipe of the lower tank of an RH refining furnace, wherein the components of the heat-insulating coating include: binder, refractory powder, functional filler, additives and water;

[0091] The binder accounts for 36% to 50%, and the binder includes one or more of silica sol, aluminum sol, aluminum dihydrogen phosphate, and water glass;

[0092] The refractory powder accounts for 8% to 20%, and the refractory powder includes one or more of alumina micro powder, magnesium aluminum spinel micro powder, and mullite micro powder.

[0093] The functional filler comprises 23% to 35% of the total content, and includes one or more of mica powder, hollow glass microspheres, hollow ceramic microspheres, cenospheres, and titanium dioxide; the additive comprises 1% to 3% of the total content, and includes dispersants and / or explosion-proof agents.

[0094] The water addition is 18% to 30%.

[0095] Furthermore, the binder accounts for 48%, specifically including alumina sol; the refractory powder accounts for 8%, including alumina micro powder and / or magnesium aluminum spinel micro powder; the functional filler accounts for 24%, specifically including hollow ceramic microspheres, mica powder and / or cenospheres; the additives account for 1.5%, specifically including dispersants and explosion-proof agents; and the moisture content accounts for 18.5%.

[0096] Furthermore, the binder accounts for 38%, specifically including water glass; the refractory powder accounts for 9%, specifically including alumina micro powder and / or mullite micro powder; the functional filler accounts for 27%, specifically including mica powder, titanium dioxide and / or cenospheres; the additives account for 1%, specifically including dispersants and explosion-proof agents; and the moisture content accounts for 25%.

[0097] The technical solutions of the present invention will be described in detail below with reference to specific application examples. For technical details not described in the implementation process, please refer to the relevant descriptions above.

[0098] This invention provides a convenient, thin, and heat-insulating lining structure for the lower trough of an RH refining furnace. It comprises three layers from the outside in: a steel shell, a heat-insulating layer, and a working layer. The working layer is constructed of magnesium spinel bricks, and the gap between the working layer and the heat-insulating layer is filled with corundum spinel castable.

[0099] Furthermore, the heat insulation layer is formed by applying a heat insulation coating.

[0100] Furthermore, the thickness of the heat insulation coating is 1-3 mm.

[0101] Furthermore, after the heat insulation coating is applied, it can be cured at room temperature for 6-8 hours, and the curing time can be shortened when the temperature is high.

[0102] Furthermore, the thermal insulation coating is composed of the following raw materials by weight percentage: binder 36-50%, preferably one or more of silica sol, alumina sol, aluminum dihydrogen phosphate, and water glass; refractory powder: 8-20%, preferably one or more of alumina micro powder, magnesium aluminum spinel micro powder, and mullite micro powder; functional filler: 23-35%, preferably one or more of mica powder, hollow glass microspheres, hollow ceramic microspheres, cenospheres, and titanium dioxide; additives: 1-3%, including dispersants, explosion retardants, etc., with a water content of 18-30%.

[0103] The binder serves to bond the various components in the coating together, forming a dense coating. Preferably, the binder includes one or more inorganic aqueous solutions such as silica sol, aluminum sol, aluminum dihydrogen phosphate, and water glass. The binder has excellent high-temperature resistance and bonding strength, low corrosiveness to steel shells, and produces no gas during use compared to organic binders, making it environmentally friendly.

[0104] Water glass is an air-hardening cementitious material with sodium silicate as its main component. It has the characteristics of strong adhesion and good heat resistance, and can combine the various parts of the coating together to form a stable coating system.

[0105] Silica sol and aluminum sol are gelling materials with silica and alumina as the main components, respectively. They exhibit excellent weather resistance and abrasion resistance in the coatings industry, and can bond well with a variety of substrates to improve the adhesion of coatings.

[0106] The tripolyphosphate ions in aluminum dihydrogen phosphate molecules can chelate with metal ions to form a stable passivation film on the coating surface, inhibiting the corrosion of steel. After room temperature curing, the coating structure can remain stable, withstand thermal shock, and enhance the wear resistance and mechanical properties of the coating.

[0107] The refractory powder serves to improve the high-temperature resistance and mechanical strength of the coating, while also being compatible with the permanent layer material. Preferably, the refractory powder includes one or more of alumina micropowder, magnesium aluminum spinel micropowder, and mullite micropowder, and the refractory powder exhibits good high-temperature volume stability and excellent thermal shock resistance.

[0108] The functional filler serves to reduce the thermal conductivity of the coating, improve its heat insulation effect, enhance its mechanical strength and adhesion, and improve its application performance. Preferably, the functional filler includes one or more of mica powder, hollow glass microspheres, hollow ceramic microspheres, cenospheres, and titanium dioxide, exhibiting low thermal conductivity, excellent weather resistance, high mechanical strength, and good adhesion.

[0109] The additives are used to improve the application performance and stability of the coating. Preferably, the additives include dispersants and anti-explosion agents, etc. Dispersants can effectively improve the dispersibility, flowability and stability of the coating, while anti-explosion agents can reduce the occurrence of coating cracking during baking.

[0110] The embodiments of the present invention have the following technical effects:

[0111] The lower tank section of the RH refining furnace employs a three-layer structure: a steel shell, an insulation layer (thermal insulation coating), and a working layer (magnesia spinel bricks). The thermal insulation coating formula offers advantages such as low cost, safety and environmental friendliness, excellent insulation performance, and convenient application.

[0112] 1. Low cost / safe and environmentally friendly: The coating uses inorganic binders, which are cheaper than the organic binders used in the existing building / protective coating field. Inorganic binders are less likely to react and form harmful gases at high temperatures, making them safe and environmentally friendly.

[0113] 2. Easy to apply: Simply mix the binder, refractory powder, functional filler, additives and water in a certain proportion and apply it to the inner wall of the short tube in the lower part of the RH refining furnace. The operation is simple and the construction is convenient.

[0114] 3. Small insulation layer thickness: Compared with insulation materials such as nanofiber board and calcium silicate insulation board, the insulation layer formed by applying heat insulation coating is thinner, eliminating the need for designing arc-shaped bricks and not affecting the steel flow rate of the immersion tubes when using the RH refining furnace.

[0115] 4. Excellent thermal insulation effect: The coating uses mica powder, hollow glass microspheres, hollow ceramic microspheres, and cenospheres as functional fillers, which gives the coating a low thermal conductivity. This effectively controls the heat conduction of molten steel to the steel shell at the bottom of the RH refining furnace and reduces the temperature of the steel shell.

[0116] The following description uses another embodiment:

[0117] Combined with appendix Figure 2 The lining structure of the lower trough short tube of the RH refining furnace comprises three layers. From the outside to the inside, these layers are a steel shell, an insulation layer, and a working layer. The insulation layer is a heat-insulating coating, and the working layer is magnesia spinel brick.

[0118] The RH refining furnace heat insulation coating of this embodiment comprises the following components by weight percentage: binder (silica sol) 45%, refractory powder (alumina micro powder) 10%, functional filler (hollow glass microspheres, titanium dioxide, mica powder) 23%, additives (dispersant, explosion retardant) 1.2%, and moisture 20.8%.

[0119] The following description uses another embodiment:

[0120] Combined with appendix Figure 2 The lining structure of the lower trough short tube of the RH refining furnace comprises three layers. From the outside to the inside, these layers are a steel shell, an insulation layer, and a working layer. The insulation layer is a heat-insulating coating, and the working layer is magnesia spinel brick.

[0121] The RH refining furnace heat insulation coating of this embodiment comprises the following components by weight percentage: binder (alumina sol) 48%, refractory powder (alumina micro powder, magnesium aluminum spinel micro powder) 8%, functional filler (hollow ceramic microspheres, mica powder, cenospheres) 24%, additives (dispersant, explosion retardant) 1.5%, and moisture 18.5%.

[0122] The following description uses another embodiment:

[0123] Combined with appendix Figure 2 The lining structure of the lower trough short tube of the RH refining furnace comprises three layers. From the outside to the inside, these layers are a steel shell, an insulation layer, and a working layer. The insulation layer is a heat-insulating coating, and the working layer is magnesia spinel brick.

[0124] The RH refining furnace heat insulation coating of this embodiment comprises the following components by weight percentage: binder (water glass) 38%, refractory powder (alumina micro powder, mullite micro powder) 9%, functional filler (mica powder, titanium dioxide, cenospheres) 27%, additives (dispersant, explosion retardant) 1%, and moisture 25%.

[0125] The following description uses another embodiment:

[0126] A thermal insulation coating for the short pipe of the lower trough of an RH refining furnace is used as a thermal insulation layer in the inner lining structure of the short pipe of the lower trough of an RH refining furnace. The thermal insulation coating is composed of the following raw materials by weight percentage: binder 36-50%, preferably one or more of silica sol, alumina sol, aluminum dihydrogen phosphate, and water glass; refractory powder: 8-20%, preferably one or more of alumina micro powder, magnesium aluminum spinel micro powder, and mullite micro powder; functional filler: 23-35%, preferably one or more of hollow glass microspheres, hollow ceramic microspheres, cenospheres, titanium dioxide, and talc; additives: 1-3%, including dispersants, anti-explosion agents, etc., and water content of 18-30%.

[0127] The binder serves to bond the various components in the coating together, forming a dense coating. Preferably, the binder includes aqueous solutions of inorganic substances such as silica sol, aluminum sol, aluminum dihydrogen phosphate, and water glass. The binder has excellent high-temperature resistance and bonding strength, low corrosiveness to steel shells, and produces no gas during use, making it environmentally friendly.

[0128] The refractory powder serves to improve the high-temperature resistance and mechanical strength of the coating, while also being compatible with the permanent layer material. Preferably, the refractory powder includes alumina micro powder, magnesium aluminum spinel micro powder, and mullite micro powder; the refractory powder exhibits good high-temperature volume stability and excellent thermal shock resistance.

[0129] The function of the functional filler is to reduce the thermal conductivity of the coating, improve its heat insulation effect, enhance its mechanical strength and adhesion, and improve its application performance. Preferably, the functional filler includes hollow glass microspheres, hollow ceramic microspheres, cenospheres, titanium dioxide, talc, etc., and has low thermal conductivity, excellent weather resistance, high mechanical strength, and good adhesion.

[0130] The additives are used to improve the application performance and stability of the coating. Preferably, the additives include dispersants and anti-explosives. The additives can effectively improve the dispersibility, flowability, and stability of the coating, while the anti-explosives can reduce the occurrence of baking cracking in the coating.

[0131] Furthermore, the heat insulation coating is applied to the inner wall of the lower trough short pipe steel shell, with a coating thickness of 1-3mm during construction.

[0132] Furthermore, after the heat insulation coating is applied, it can be dried at room temperature for 6 hours. The drying time can be shortened when the temperature is high.

[0133] The embodiments of the present invention have the following technical effects:

[0134] 1. Convenient Construction: Simply mix the binder, refractory powder, functional filler, additives, and water in a specific ratio, and then apply it to the inner wall of the steel shell of the lower trough short pipe in the RH refining furnace. The operation is simple and convenient, and it also has good compatibility with corundum spinel castable (the sealant between the working layer and the thermal insulation layer). The structure of the impregnated short pipe, from the outside to the inside, consists of a steel shell, thermal insulation coating, sealant castable, and magnesia spinel bricks. The coating is applied to the steel shell. The refractory powder used in the coating has a similar composition to that of the sealant castable, making it easier to form a cohesive whole.

[0135] 2. Small thermal insulation layer thickness (1-3mm): Compared with shaped thermal insulation materials such as nanofiber board and calcium silicate insulation board (10-20mm thick), the thermal insulation layer formed by applying thermal insulation coating is thin and does not affect the steel flow rate of the immersion tube when using the RH refining furnace.

[0136] 3. Excellent thermal insulation effect: Using hollow glass microspheres, hollow ceramic microspheres, cenospheres, talc powder, etc., as functional fillers, the thermal insulation coating has a low thermal conductivity (0.101 W / (m×K)) and bulk density (0.749 g / cm3), effectively mitigating heat radiation and conduction from molten steel to the bottom of the lower tank and the sidewalls of the short pipes in the lower tank, thus reducing the temperature of the steel shell. When the thermal insulation coating was applied to a steel plate and placed in front of the furnace door of an 800℃ medium-temperature furnace for a period of time, the temperature of the steel plate with the coating was measured to be approximately 148℃ lower than that without the coating.

[0137] The thermal insulation coating uses an inorganic binder, which does not generate harmful gases and is relatively environmentally friendly. The use of refractory powder and functional fillers ensures that the coating can withstand high temperatures of 600℃ and also facilitates on-site construction.

[0138] The following description uses another embodiment:

[0139] A thermal insulation coating for the short pipes of the lower trough of an RH refining furnace, used as a thermal insulation layer in the inner lining structure of the short pipes of the lower trough of an RH refining furnace, is formulated according to the following weight percentages: binder (silica sol) 45%, refractory powder (alumina micro powder) 10%, functional fillers (hollow glass microspheres, titanium dioxide, talc) 23%, additives (dispersant, explosion retardant) 1.2%, and moisture 20.8%.

[0140] The construction of thermal insulation coating includes the following steps: 1. Clean and grind the adhering substances on the inner wall of the lower trough short pipe steel shell; 2. Weigh the above proportions of binder, refractory powder, functional filler, additives and other components with an electronic scale, add an appropriate amount of tap water and stir evenly; 3. Apply the thermal insulation coating to the surface of the steel shell with a brush, with a coating thickness of 1mm.

[0141]

[0142]

[0143]

[0144] Table 2 Comparison of steel shell temperatures with and without thermal insulation layer (1mm)

[0145] When the thickness of the thermal insulation layer is 1mm, 88 heats of RH furnace without thermal insulation layer were produced, and 102 heats of RH furnace with thermal insulation layer were produced (tested in another production area, the test steel grade and operating conditions differ from Table 1). Table 2 shows that the test data generally showed no obvious pattern. The average temperature drop of the first 34 heats was taken as the effective thermal insulation temperature of the coating. Therefore, the steel shell with thermal insulation layer reduced the steel shell temperature by an average of 30℃, with a maximum reduction of 94℃. The effective thermal insulation heats were 34 heats. Therefore, to achieve a certain insulation effect, the thickness of the thermal insulation coating should not be less than 1mm. However, if the coating thickness is too large, it will slip due to gravity and the curing time will increase. Experimental data collected with coating thicknesses of 1mm and 3mm showed that 1mm was too thin, with no obvious pattern in the effect. 3mm significantly improved the initial temperature range, service life, average thermal insulation temperature, and maximum temperature. It is theoretically feasible to continue applying a thicker layer of paint, but if the paint is too thick, the curing time will be longer, and the paint will tend to slide downwards due to gravity.

[0146] The following description uses another embodiment:

[0147] A heat-insulating coating for the short tubes of the lower trough of an RH refining furnace, used as a heat-insulating layer in the inner lining structure of the short tubes of the lower trough of an RH refining furnace, is formulated according to the following weight percentages: binder (alumina sol) 48%, refractory powder (alumina micro powder, magnesium aluminum spinel micro powder) 8%, functional filler (hollow ceramic microspheres, talc powder, cenospheres) 24%, additives (dispersant, explosion retardant) 1.5%, and moisture 18.5%.

[0148] The construction of thermal insulation coating includes the following steps: 1. Clean and grind the adhering substances on the inner wall of the lower trough short pipe steel shell; 2. Weigh the above proportions of binder, refractory powder, functional filler, additives and other components with an electronic scale, add an appropriate amount of tap water and stir evenly; 3. Apply the thermal insulation coating to the surface of the steel shell with a brush, with a coating thickness of 2mm.

[0149] The following description uses another embodiment:

[0150] A heat-insulating coating for the short pipe of the lower trough of an RH refining furnace, used as a heat-insulating layer in the inner lining structure of the short pipe of the lower trough of an RH refining furnace, is formulated according to the following weight percentages: binder (water glass) 38%, refractory powder (alumina micro powder, mullite micro powder) 9%, functional filler (hollow ceramic microspheres, talc powder, titanium dioxide, cenospheres) 27%, additives (dispersant, anti-explosion agent) 1%, and water 25%.

[0151] The construction of thermal insulation coating includes the following steps: 1. Clean and grind the adhering substances on the inner wall of the lower trough short pipe steel shell; 2. Weigh the above proportions of binder, refractory powder, functional filler, additives and other components with an electronic scale, add an appropriate amount of tap water and stir evenly; 3. Apply the thermal insulation coating to the surface of the steel shell with a brush, with a coating thickness of 3mm.

[0152] The following description uses another embodiment:

[0153] This invention provides a thin-walled, highly insulating lower trough short pipe insulation lining structure, which is also a type of insulation lining structure for the lower trough short pipe of an RH refining furnace. It comprises three layers from the outside in: a steel shell, an insulation layer, and a working layer. The working layer is constructed using chromium-free magnesium spinel bricks, and the gap between the working layer and the insulation layer is filled with corundum spinel castable. The insulation layer is coated with an insulation paint (its structure is as follows). Figure 3 (As shown).

[0154] Combined with appendix Figure 3 The aforementioned lining structure for the lower trough short tube of the RH refining furnace comprises three layers, distributed from the outside to the inside: a steel shell, a thermal insulation layer, and a working layer. Its implementation consists of the following five steps: 1. Cleaning and polishing the adhering substances from the inner wall of the steel shell of the lower trough short tube; 2. Mixing the thermal insulation powder and binder evenly in a certain proportion, adding an appropriate amount of tap water to adjust the consistency of the thermal insulation coating; 3. Applying the thermal insulation coating to the surface of the steel shell with a brush, with a coating thickness of 1-3 mm; 4. After the thermal insulation coating dries, constructing the magnesia spinel brick working layer; 5. Filling the gap between the working layer and the thermal insulation layer with corundum spinel castable to form the thermal insulation lining structure of the lower trough short tube of the RH refining furnace.

[0155] Furthermore, the powder and binder are mixed in a certain proportion and stirred evenly. Then, the mixture is applied to the inner wall of the lower trough short pipe steel shell and dried at room temperature for a few hours before the construction of the working layer can begin.

[0156] Furthermore, the thickness of the heat insulation coating should be 1-3mm. If it is too thick, it is easy to peel off under the action of gravity, and if it is too thin, the heat insulation effect will be poor.

[0157] The embodiments of the present invention have the following technical effects:

[0158] 1. The construction of this heat insulation lining structure is convenient, the drying speed is fast, and the adhesion is strong.

[0159] 2. The materials used in the working layer and thermal insulation layer of this thermal insulation lining structure meet environmental protection requirements (the working layer uses Cr-free material and the thermal insulation layer uses inorganic binder).

[0160] 3. This heat-insulating lining structure can alleviate the high temperature of the short tubes in the lower part of the RH refining furnace and the bottom steel shell of the channel, without affecting the RH treatment efficiency.

[0161] It should be understood that the specific order or hierarchy of steps in the disclosed process is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process may be rearranged without departing from the scope of this disclosure. The appended method claims provide elements of various steps in an exemplary order and are not intended to limit the scope to the specific order or hierarchy described.

[0162] In the above detailed description, various features are combined together in a single embodiment to simplify this disclosure. This approach to disclosure should not be construed as reflecting an intention that embodiments of the claimed subject matter require more features than are explicitly stated in each claim. Rather, as reflected in the appended claims, the invention is presented with fewer features than all of the features of the single disclosed embodiment. Therefore, the appended claims are hereby explicitly incorporated into the detailed description, wherein each claim stands alone as a preferred embodiment of the invention.

[0163] The disclosed embodiments have been described above to enable any person skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments without departing from the spirit and scope of this disclosure. Therefore, this disclosure is not limited to the embodiments given herein, but is consistent with the broadest scope of the principles and novel features disclosed in this application.

[0164] The foregoing description includes examples of one or more embodiments. It is certainly impossible to describe all possible combinations of components or methods in order to describe the above embodiments, but those skilled in the art will recognize that further combinations and arrangements of the various embodiments are possible. Therefore, the embodiments described herein are intended to cover all such changes, modifications, and variations falling within the scope of the appended claims. Furthermore, the term "comprising" as used in the specification or claims is used in a manner similar to the term "including." Additionally, the use of any term "or" in the specification of the claims is intended to mean "non-exclusive or."

[0165] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for heat insulation of the short tube in the lower part of an RH refining furnace, characterized in that, include: Clean and grind the adhering material on the inner wall of the lower groove short pipe steel shell (2); Apply heat-insulating coating to the inner wall of the steel shell (2) of the short pipe of the lower tank of the RH refining furnace. After drying at room temperature, a heat-insulating layer (3) is formed. The thickness of the heat-insulating layer (3) is 1 to 3 mm. Along the inner wall of the heat insulation layer (3), refractory bricks are laid to form a cylindrical working layer (4); A filler layer (5) is formed by injecting castable material between the working layer (4) and the heat insulation layer (3); The lower trough short pipe (1) of the RH refining furnace includes: a cylindrical steel shell (2), a heat insulation layer (3) disposed on the inner wall of the steel shell, and a cylindrical working layer (4) disposed on the inner side of the heat insulation layer; the working layer is used to directly contact the molten steel and provide the molten steel with a high-temperature resistant and erosion-resistant pipe; the heat insulation layer is formed by applying heat insulation coating.

2. The heat insulation method for the short tube in the lower tank of an RH refining furnace as described in claim 1, characterized in that, The components of the thermal insulation coating include: binder, refractory powder, functional filler, additives and water.

3. The heat insulation method for the short tube in the lower tank of an RH refining furnace as described in claim 2, characterized in that, The binder accounts for 36% to 50%, and the binder includes one or more of silica sol, aluminum sol, aluminum dihydrogen phosphate, and water glass.

4. The heat insulation method for the short pipe of the lower tank of the RH refining furnace as described in claim 2, characterized in that, The refractory powder accounts for 8% to 20% of the total content, and the refractory powder includes one or more of alumina micro powder, magnesium aluminum spinel micro powder, and mullite micro powder.

5. The heat insulation method for the short pipe in the lower tank of an RH refining furnace as described in claim 2, characterized in that, The functional filler comprises 23% to 35% of the total content, and includes one or more of mica powder, hollow glass microspheres, hollow ceramic microspheres, cenospheres, and titanium dioxide; the additive comprises 1% to 3% of the total content, and includes dispersants and / or explosion-proof agents. The water addition is 18% to 30%.

6. The heat insulation method for the short pipe of the lower tank of the RH refining furnace as described in claim 2, characterized in that, The binder accounts for 48%, specifically including alumina sol; the refractory powder accounts for 8%, including alumina micro powder and / or magnesium aluminum spinel micro powder; the functional filler accounts for 24%, specifically including hollow ceramic microspheres, mica powder and / or cenospheres; the additives account for 1.5%, specifically including dispersants and explosion-proof agents; and the moisture content accounts for 18.5%.

7. The heat insulation method for the short pipe of the lower tank of the RH refining furnace as described in claim 2, characterized in that, The binder accounts for 38%, specifically including water glass; the refractory powder accounts for 9%, specifically including alumina micro powder and / or mullite micro powder; the functional filler accounts for 27%, specifically including mica powder, titanium dioxide and / or cenospheres; the additives account for 1%, specifically including dispersants and explosion-proof agents; and the moisture content accounts for 25%.

8. The heat insulation method for the short tube in the lower tank of an RH refining furnace as described in claim 1, characterized in that, The specific method for heat insulation of the short tube in the lower part of the RH refining furnace is as follows: Clean and grind the adhering material on the inner wall of the lower groove short pipe steel shell (2); Weigh the binder, refractory powder, functional filler and additives in a preset ratio using an electronic scale, add water and stir evenly to form a heat insulation coating. Apply the heat insulation coating to the inner surface of the lower short pipe steel shell with a brush. The coating thickness is 3 mm. After drying at room temperature, a heat insulation layer (3) is formed. The thickness of the heat insulation layer (3) is 3 mm. Along the inner wall of the heat insulation layer (3), refractory bricks are laid to form a cylindrical working layer (4); A filler layer (5) is formed by injecting castable material between the working layer (4) and the heat insulation layer (3); The thermal insulation coating comprises: 39% binder, specifically 39% water glass; 10% refractory powder, specifically 7% alumina micro powder and 3% magnesium aluminum spinel micro powder; 27% functional filler, specifically 5% hollow glass microspheres, 7% titanium dioxide, 7% mica powder and 8% cenospheres; 1.2% additives, specifically 0.2% dispersant and 1% explosion-proof agent; and 22.8% moisture.

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