Before discussing the castables used in the horizontal flue of circulating fluidized bed boilers, we first need to understand the basic working principles of circulating fluidized bed boilers and their special working environment. Circulating fluidized bed boiler, as an efficient and environmentally friendly combustion technology, its internal horizontal flue is an important channel for flue gas circulation during the combustion process. Therefore, it is crucial to select suitable castable materials.
Circulating fluidized bed boiler horizontal flue:
The horizontal flue in a circulating fluidized bed boiler is a key passage for flue gas to be transmitted from the furnace to the cyclone separator. Its design and construction reflect a high degree of professionalism and fine process considerations. This part of the structure is mainly made of bricks with high temperature resistance and excellent wear resistance, especially at the bottom and both sides of the walls. This special material is selected to resist the continuous erosion of high-temperature smoke. The top of the flue uses wear-resistant castables specially designed for high-temperature, high-wear environments to ensure the stability and durability of the entire flue.
At the entrance of the horizontal flue, the designers paid special attention. Since this is the only place where high-speed flue gas carries a large amount of unburned coal particles and fly ash, and the flue gas will undergo a sharp 90-degree turn here, the impact on the water wall is particularly strong. In order to meet this challenge, pins were specially welded to the fire surface of the water-cooled wall, and a 400mm wide high-temperature and wear-resistant castable was added to strengthen the structure and reduce wear.
It is worth noting that the flow area of the horizontal flue is relatively small, which causes the flue gas flow rate to increase significantly when entering the channel from the furnace. In addition, its cross-section is designed in the shape of a tapered nozzle, so the flow rate of flue gas gradually accelerates as it flows through. When it reaches the inlet of the cyclone separator, the wind speed can be as high as 12 to 18 meters per second. This high-speed flow not only causes significant wear on the flue walls, but may also cause vibration problems. Therefore, the ultimate pursuit of professionalism and durability is reflected in material selection and structural design.
Requirements for castables for horizontal flue of circulating fluidized bed boiler:
The horizontal flue of circulating fluidized bed boilers usually uses refractory castables as lining materials to resist high temperature, corrosion and erosion of combustion products in the flue. Suitable castables can provide good fire resistance and stability.
In the horizontal flue of the circulating fluidized bed boiler, due to the high temperature, high-speed flow of flue gas and the possible presence of corrosive gases, the high temperature resistance, thermal shock resistance, wear resistance and corrosion resistance of the castable are affected. Extremely demanding. Due to these harsh working conditions, the castables typically chosen are those that can withstand extreme temperatures and have excellent thermal and chemical stability.
At present, in the horizontal flue of circulating fluidized bed boilers, the widely used castables mainly include high-aluminum wear-resistant and refractory castables and high-strength acid-resistant castables.
High-aluminum wear-resistant refractory castables can maintain stable physical and chemical properties at high temperatures and effectively resist flue gas erosion and high-temperature erosion. The high-strength acid-resistant castable is particularly suitable for flue gas environments containing corrosive gases. It can resist the erosion of acid gases and protect the flue wall from damage.
When selecting specific castables, comprehensive considerations need to be made based on factors such as the actual operating parameters of the boiler, fuel type, and flue gas composition. For example, if the boiler burns high-sulfur fuel, then a castable with greater acid resistance will need to be selected to deal with the sulfides in the flue gas.
High-strength acid-resistant castable
High-strength acid-resistant castable is a high-performance material made of professionally proportioned acid-resistant aggregates, powders and efficient water glass or phosphate binders. Its remarkable feature is its excellent acid resistance, which makes it widely used in kiln linings in metallurgy, electric power, chemical industry and other fields.
This acid-resistant castable has been carefully designed to have excellent anti-corrosion capabilities and can effectively withstand a variety of acidic environments. However, it is important to note that its resistance to specific chemicals such as hydrofluoric acid and high fatty acids is relatively weak, which requires special attention in practical applications.
In addition to acid resistance, the castable exhibits excellent physical properties, including high hardness, good toughness, excellent wear resistance and temperature resistance. These properties enable it to remain stable for long periods of time in extreme acidic environments, greatly reducing equipment maintenance costs and downtime.
From a professional perspective, high-strength acid-resistant castables not only meet the anti-corrosion requirements in acidic environments, but also show excellent performance in complex and changeable industrial environments. It is one of the indispensable high-performance materials in modern industry, providing a strong guarantee for the stable operation of various acidic process environments.
High aluminum wear-resistant refractory castable
① Introduction to high-aluminum wear-resistant refractory castables
High-aluminum wear-resistant refractory castable, as a high-performance refractory material, is favored by the industry for its excellent fire resistance and excellent wear resistance. This specially designed material is widely used in refractory linings of high-temperature industrial furnaces, where it performs particularly well in critical areas susceptible to wear.
High-aluminum wear-resistant refractory castables are based on high-aluminum materials, such as alumina, corundum, etc., ensuring their high fire resistance. At the same time, its stability and high temperature resistance are further enhanced by carefully selecting and adding auxiliary materials such as quartz powder, mica, and calcium silicate. More importantly, in order to improve the wear resistance of the material, professional wear-resistant ingredients such as zirconia and corundum are specially incorporated. The addition of these high-performance materials enables high-aluminum wear-resistant and refractory castables to maintain excellent durability in the face of extreme wear and tear.
In short, high-aluminum wear-resistant refractory castables, with their professional composition design and excellent performance, have become indispensable refractory materials in high-temperature industrial furnaces, providing a solid guarantee for the continuity and stability of industrial production. .
② Characteristics and performance of high-aluminum wear-resistant refractory castables
(1) Excellent fire resistance: This castable can withstand extreme high temperatures up to 1800°C, showing excellent fire resistance. The core advantage of this property is due to its high content of alumina and corundum, two materials known for their high melting point and excellent fire resistance, thus ensuring the stability of the castable in high-temperature environments.
(2) Significant wear resistance: By adding special wear-resistant materials, the hardness and wear resistance of high-aluminum wear-resistant refractory castables have been significantly improved. This enhancement enables the material to maintain long-term durability in continuous high-temperature and high-pressure working environments, reduce maintenance costs, and improve production efficiency.
(3) Strong slag resistance: In high-temperature operations, the generation of chemical slag is inevitable. High-aluminum wear-resistant refractory castables effectively resist the erosion of these chemical slags through their unique composition design, thus greatly extending the service life of the furnace lining and ensuring the continuity and safety of the production process.
(4) Excellent construction performance: High-aluminum wear-resistant and refractory castables are not only easy to construct through various methods such as pouring and spraying, but also have fast curing speed and can achieve high strength after curing. This feature significantly improves construction efficiency, shortens the construction period, and saves time and costs for enterprises.
③ Application fields of high-aluminum wear-resistant castables
High-aluminum wear-resistant castables play a pivotal role in many industries with their excellent wear resistance and high-temperature stability. Next, let’s take an in-depth look at its specific applications in various industries.
In the steel industry, high-aluminum wear-resistant castables are widely used in the furnaces, hearths, tops and doors of key equipment such as electric furnaces, converters, heating furnaces and melting furnaces. These parts have extremely high requirements on the wear resistance and high temperature resistance of refractory materials in high-temperature and heavy-load working environments, and high-aluminum wear-resistant castables are ideal for meeting these harsh conditions.
In the petrochemical industry, the refractory linings of core equipment such as cracking furnaces, hydroconverters, and catalytic cracking units also rely on high-aluminum wear-resistant castables. In these devices, the aggressive environments created by high temperatures and chemical reactions pose severe challenges to refractory materials. High-aluminum wear-resistant castables ensure the safe and efficient operation of these equipments with their excellent wear resistance and chemical stability.
In the building materials industry, the refractory lining of high-temperature furnaces such as cement rotary kilns, glass kilns and ceramic kilns is also an important application area of high-aluminum wear-resistant castables. These furnaces need to withstand extremely high temperatures and wear during the production process. The excellent performance of high-aluminum wear-resistant castables provides a strong guarantee for the long-term stable operation of these equipments.
In addition, in the non-ferrous metal industry, such as refractory linings of aluminum electrolytic cells, copper smelting furnaces and nickel furnaces, high-aluminum wear-resistant castables also show their indispensable value. In the power industry, whether it is the refractory lining of coal-fired, gas-fired or biomass power plant boilers, high-aluminum wear-resistant castables have won wide applications due to their excellent performance.
It is worth mentioning that in the waste incineration industry, high-aluminum wear-resistant castables are also widely used as refractory linings for waste incinerators. In the face of harsh environments such as high temperatures, corrosive gases and fly ash generated during waste incineration, high-aluminum wear-resistant castables have demonstrated excellent durability and stability.
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