Refractory and thermal-insulating spray coating material and preparation method and application thereof

Abstract

The invention discloses a refractory and thermal-insulating spray coating material, and a preparation method and an application thereof. The refractory and thermal-insulating spray coating material comprises two parts, namely a prefabricated slurry and a curing agent, wherein the prefabricated slurry is prepared with a refractory aggregate and a binder; the weight of the refractory aggregate is 60-63 percent of the total weight of the refractory and thermal-insulating spray coating material; the weight of the binder is 34-37 percent of the total weight of the refractory and thermal-insulating spray coating material; and the weight of the curing agent is 3-6 percent of the total weight of the refractory and thermal-insulating spray coating material. According to the preparation method, the refractory and thermal-insulating spray coating material is prepared by evenly mixing the weighed refractory aggregate, the weighed binder and the weighed curing agent in sequence. A large-aperture spray gun for spraying coarse sand is adopted for quickly spraying the uniformly stirred slurry onto the surface of the inner wall of a furnace lining to prevent the slurry from being cured due to long-term storage, and then the refractory and thermal-insulating spray coating material is put into production directly. The refractory and thermal-insulating spray coating material has high interfacial bonding strength with the furnace lining, high resistance against furnace gas erosion, excellent thermal shock stability and high infrared radiance.

Description

technical field [0001] The invention relates to a fire-resistant and heat-insulating spray coating, in particular to a fire-resistant and heat-insulating spray coating for heat insulation of a high-temperature working surface of a steel rolling heating furnace lining, a preparation method and an application thereof. Background technique [0002] Energy and environmental issues are important concerns of modern society, and they are also one of the main issues restricting the rapid development of iron and steel enterprises. Energy saving and consumption reduction and emission reduction are the inevitable choices for technological progress and sustainable development of iron and steel enterprises. The heating furnace is the key equipment and energy consumer of billet hot rolling, and its energy consumption accounts for 75-80% of the energy consumption of the steel rolling process. Therefore, energy saving in the heating furnace is a key factor affecting the energy consumption o...

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Problems solved by technology

According to the above two patent reports, it can be seen that the patented technology has the characteristics of low rebound rate, low thermal conductivity and good heat preservation effect, but due to the shortage of low operating temperature, it cannot meet the high temperature heating conditions of the steel rolling heating furnace

[0005] In 2004, Huang Hong et al. published "Application of Polycrystalline Mullite Refractory Fiber and Infrared Spraying Coating Combination on Walking Furnace of Liuzhou Iron and Steel Bar Line Factory and Energy Saving Analysis" in ≤Guangxi Energy Conservation≥. Laishi fiber is pasted on the furnace wall of the walking heating furnace and the working surface of the water-cooled beam, and the energy-saving transformation of spraying high-temperature far-infrared paint on the surface of the fiber effectively reduces the heat loss of water cooling and the heat loss of the furnace wall, and achieves a reduction in the heating furnace. Excellent effect of energy consumption of 8.42Kgce / t steel, but in actual production, there are also deficiencies such as shrinkage cracks between fiber blocks, fiber washing off, thermal shock peeling, etc.

In 2011, Liu Yunheng published "Application of Polycrystalline Mullite Fiber in Annular Heating Furnace" in ≤Industrial Furnace≥. This paper introduced the characteristics of polycrystalline mullite fiber and its construction method, and compared and analyzed the lining paste The temperature changes of the furnace wall before and after the polycrystalline mullite fiber patch, the structure shows that after the fiber is pasted, the average temperature of the inner and outer ring furnace wall steel plates and the furnace roof of the heating furnace are respectively reduced by 9.8 ℃, 14.1 ℃ and 37.2 ℃, effectively The heat dissipation on the surface of the furnace body is greatly reduced. After calculation, the annual cost of gas can be saved by about 500,000 yuan; at the same time, the heating and cooling speed of the furnace is accelerated when the furnace is stopped, and the rolling is started (waiting), which shortens the heating time of the billet and reduces the time spent on the billet. The burning loss in the heating furnace improves the unit output of the furnace, and the oxidation burning loss is reduced from the original 1.5% to the current 1.342%, which is better adapted to the situation of unsaturated production and frequent stop (waiting) production; After 1 year and 10 months, it was found that about 15% of the fiber patches had fallen off during the shutdown inspection

Due to the high rebound rate of refractory fiber spraying and the high price of polycrystalline refractory fibers, the refractory fiber spraying technology only uses ordinary ceramic fibers for spraying construction. The highest long-term service temperature of the fiber spray coating is ≤1200°C. Polycrystalline alumina fibers cannot be sprayed with refractory fibers due to their brittleness, short fiber length, and small diameter.

[0007] According to the above relevant information reports, in the existing high-temperature steel rolling heating furnace lining inner wall heat insulation strengthening and radiation performance improvement technologies, there are mainly heat insulation technology represented by polycrystalline mullite fiber patch and its surface infrared radiation coating. Strengthening technology, however, due to the low bonding strength between the polycrystalline mullite fiber patch and the original furnace lining, there are deficiencies such as shedding, erosion and fiber shrinkage cracks to varying degrees, resulting in short service life and rapid deterioration of thermal performance of industrial furnaces fast, affecting the operational stability of industrial furnaces

For the heat insulation technology of the inner wall of the furnace lining of the light-weight heat-insulating spray coating, in order to improve the bonding strength between the coating and the inner wall of the furnace lining, it is generally necessary to add a large amount of sintering promoting materials to facilitate the formation of a firm ceramic interface between the sprayed coating and the furnace lining. It is relatively low, and it is difficult to meet the high-temperature performance requirements of steel rolling heating furnaces. So far, there have been no relevant reports on the application of heat-insulating spray coatings on the inner wall of high-temperature steel rolling heating furnace linings.

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