Fire-Resistant Plastic for Power Plant Boiler
The operating temperature of the high-temperature smoke mixing chamber of the power plant boiler is 1039℃. The original insulation structure was a composite of refractory brick and aluminosilicate, but after long-term use at high temperature, the refractory brick was prone to falling, burning and smoking. The CHP plant reconstructed the boiler and used refractory plastic for the refractory layer of the smoke mixing chamber of the high-temperature furnace.
Temperature Control in the Structure
This type of refractory plastic is difficult to manufacture and requires strict curing conditions. It must be heated and artificially aged to achieve lifting force. The specific heating curve is defined as follows: the natural moisture in the refractory plastic can only be released when the temperature rises from room temperature to 150 °C, and the crystallization water in the refractory plastic can only be released when the temperature rises to 500 °C, so as to achieve the strength of the rising and swelling process. However, when the high-temperature smoke mixing chamber of the boiler was reconstructed, the rising force was achieved by increasing the temperature by only 350 °C. The residual moisture did not affect the service life, and no cracks or swelling were observed. When the smoke mixing chamber of the high-temperature furnace was transformed, the temperature rising curve was reduced from 350 ℃ to 300 ℃, and its use effect was still not affected, which proves that the temperature rising curve is consistent with reality.
Construction precautions
A. The upper part of the mixing chamber is semicircular. During construction, it would need to be laid on the platform, turned over and tapped, then heated to increase the strength, and then lifted into place.
B. The insulation layer of aluminosilicate fiber needle-punched mat has a thick and flexible structure. Although a thick layer of stainless steel stretch mesh is added, it still has great elasticity and is difficult to compress when hidden.
C. The mixing chamber cannot be made in one piece. If it is divided into many parts for construction, there will be problems with the joints. Each part needs to be heated to ℃ to increase the strength before it can be lifted, and the joint filler is difficult to connect with two parts.
Technical construction measures
1. The distribution of the mixing chamber should be reasonable to facilitate heating and lifting.
2. The stainless steel handle nails should be staggered and firmly welded.
3. Use a stretched stainless steel mesh to compress the needle-punched aluminosilicate fiber.
4. The refractory plastic should be kneaded evenly, lightly whipped and compressed.
5. The number and depth of the exhaust holes should be sufficient. The distance between the rows is 150 mm × 150 mm, the depth is 60 mm.
6. The heating curve should be strictly controlled by the thyristor.
7. A V-shaped groove should be left at the joint.
During the practical application during the boiler repair period, no defects were found, which proves that this type of refractory plastic has good characteristics.
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