Design Principles and Advantages of Wear-resistant Ceramic lined Elbow Technology for Pulverized Coal Pipe in Power Plant.
Due to severe coal powder abrasion, coal power pipelines in thermal power plants use alumina wear-resistant ceramic elbows to prevent wear. This method has been approved and popularized by many power plants.
Overview of the power plant
In the pulverized coal pipeline of the thermal power plant, the pulverized coal washes the elbow of the pulverized coal pipeline, the throttling element, the lining of the coal mill and the nozzle body of the pulverized coal burner at a speed of 25 meters to 35 meters per second. Problems, so the installation of alumina ceramic wear-resistant materials second to diamond in these devices is a powerful measure to prevent wear and improve system reliability and safety.
Abrasion-resistant ceramic material (AL2O3)
Alumina ceramics uses high-purity, ultra-fine, high-quality alumina powder with a single narrow particle diameter and spray-drying granulation as the starting material. It is compacted by powder dry pressing method and uses a special mold to make its green body with high The advantages of high density, uniform density distribution, small block size tolerance and high precision. The scientific formula design and optimized sintering process make the alumina ceramics fully dense under the sintering temperature of 1520 ℃, and ensure that the fine-grained alumina ceramics have excellent mechanical properties and wear resistance.
The wear resistance of alumina ceramics was evaluated using ASTMG76-95 standards of the American Materials Testing Association and compared with several typical wear-resistant materials commonly used today, such as cast stone, wear-resistant cast iron, and wear-resistant cast steel. : The abrasion resistance of alumina ceramics is generally 6 to 8 times that of cast stone, and 4 to 6 times that of wear-resistant cast iron / steel. According to the ceramic thickness chosen (12.7-50mm), the service life of these pulverized coal parts will reach 6-30 years of operating time.
Arched design principle
The ceramic lined elbow has a “shrimp waist” structure. Firstly, computer-aided design of precise ceramic lining size. Each tile has a trapezoidal angle on both sides, so that the ceramic block and the ceramic block are closely attached without gaps. When the last piece of each circle fits tightly, a 360 ° mechanical self-locking force is formed between the ceramic block and the ceramic block, which is like the arch bridge technology that has been widely used for thousands of years to ensure that the ceramic block will not fall off. In each circle, special steel ingots are welded to the inner wall of the steel pipe through the ceramic sheet to fix the ceramic sheet. The ceramic block is also designed along the flow direction of the medium, cut into the same shape as the elbow, so that each circle of the ceramic block is closely attached without gaps. The result is a complete and reliable ceramic arch structure. During the assembly of ceramics, 1100 ℃ high-temperature refractory cement is coated between the ceramic block and the ceramic block, and between the ceramic block and the inside of the steel pipe. Its role is to enhance the joint strength between the ceramic blocks and to withstand the impact force.
Advantages of wear-resistant ceramic elbow
High-quality alumina ceramics, high-thickness ceramic wear layer, safe arch structure, long service life.
The selected alumina ceramics are made of high-quality alumina and have excellent mechanical properties and wear resistance.
The structure uses the arching principle to make the lined ceramic blocks form a 360-degree mechanical self-locking structure. The ceramic blocks with angles on the sides are interlocked and embedded in the inner wall of the steel pipe to ensure that the ceramic blocks will not fall off. The mechanical self-locking force formed by the unique arched assembly process of the ceramic elbow with inner lining ensures that the ceramic lining can withstand large material impacts and can be used for a long time under high temperature conditions. This characteristic is not possible with ordinary elbows.
Due to the use of large thickness and high quality alumina ceramics as the wear-resistant material of the elbow lining, compared with ordinary elbows, the ceramic lined elbow has a long service life. The lining ceramic is AL203, the hardness is HV1300, and the wear resistance is equivalent to that of tungsten-cobalt cemented carbide, which is ten times higher than that of steel and has a long service life. The resistance coefficient of lined ceramic steel pipe is smaller than that of ordinary steel pipe, which can reduce pipeline running resistance and reduce operating costs. The ceramic-lined steel pipe can be used for a long time in the range of -50 ℃ ～ 600 ℃.
Small size, light weight and easy installation
The lined ceramic elbow is about 20% lighter than steel pipes and wear-resistant alloy cast or cast iron pipes of the same wall thickness; about 40% to 50% lighter than cast stone composite pipes of the same inner diameter, which can reduce the cost of the bracket and lighten The labor intensity and cost during transportation, installation and maintenance can save a lot of steel. The lining ceramic elbow can adopt welding, flange connection, flexible quick joint and other connection methods. Due to the advantages of light weight, impact resistance, and no fear of bumps, transportation and construction and installation are very convenient.
The lined ceramic elbow has light weight, small size and flexible and diverse port connection forms, so it is convenient for on-site construction and transportation, lifting, and good weldability.
Not limited by shape
Alumina ceramic anti-wear design can be applied to round, square and hopper shapes.
Low cost: Compared with wear-resistant alloy cast steel pipes, the price of lined ceramic steel pipes is lighter due to its unique inlaid arch structure design. The weight-price ratio per unit length is 20% -30% lower than that of wear-resistant alloy cast steels. The total project cost is equivalent to that of cast stone, and lower than that of wear-resistant alloy cast pipe. The unique arched design not only guarantees excellent product performance, but also reduces manufacturing and installation costs. 6.5 Advantage Comparison According to the wear resistance technology table of AL2O3, it can be seen that the wear resistance of the wear-resistant ceramic elbow with an AL2O3 content of 90% is much higher than that of cast steel or bimetal elbow. The wear resistance of the tortoise shell elbow is that the sintered muddy structure has the worst wear resistance and the quality cannot be guaranteed.
At this stage, the prices of steel products remain high, and the production cost of cast steel or bimetal elbows is high, which makes their finished product prices much higher than the prices of wear-resistant ceramic lined elbows.
The weight of steel is much greater than the weight of non-metallic AL2O3 ceramics, so the cast steel or bimetal elbow has a higher weight and the installation cost is much higher than the wear-resistant ceramic lined elbow.
In summary, the wear resistance of the wear-resistant ceramic elbow is the best, easy to install and affordable.
In summary, the wear-resistant ceramic elbow has the advantages of good wear resistance, small size, light weight, flexible installation, and can save investment and other advantages. This wear-resistant ceramic elbow is a safe and reliable anti-wear method, and has been applied in many power plants, and has achieved significant results. Therefore, it is worthy of popularization and reference by relevant power plants.