The wear of the water-cooled wall tubes of the circulating fluidized bed boiler is inevitable, which is also the key factor that has plagued the development of the circulating fluidized bed boiler technology for many years. However, for the boiler user, some necessary preventive measures can be used to Reduce or even control the occurrence of water-cooled wall tube wear, thereby reducing the number of boiler shutdowns, improving the use efficiency, improving the operating reliability of the boiler, and ensuring the safe and long-term operation of the circulating fluidized bed.
1. Anti-wear countermeasures in the transition zone between the lower part of the furnace and the water-cooled wall tube The cold-state test and operation of the fluidized bed boiler show that the high-concentration solid material flow flowing down the wall has an important impact on the tube wall wear, so in the water-cooled Welding baffles (refractory and wear-resistant materials can also be poured up and down the baffles) are added to the wall pipes to prevent the solid materials flowing downward, which can achieve the purpose of anti-wear of the water-cooled wall pipes. The operation shows that the wear of the water-cooled wall tube is greatly reduced after this measure is adopted. The second anti-wear method is to change the geometry of the water-cooled wall tube, and the refractory and wear-resistant material combined with the simple elbow keeps the area of ​​the guard zone and the upper water-cooled wall tube straight. In this way, the solids flow straight down along the wall, eliminating the easy-to-grind zone. The third anti-wear method can be carried out in conjunction with the above two methods, that is, anti-wear spraying on the water-cooled wall tube in the easy-to-wear area, and this method can also be carried out alone. Almost all the circulating fluidized bed boilers currently in operation have carried out anti-wear spraying on this easy-to-grind area. It has been proved by operation that the base material of the water-cooled wall pipe will not be worn within 3 years after spraying, which effectively reduces the wear and explosion of the water-cooled wall pipe.
2. Anti-wear measures for the tube wall in the corner area around the furnace The wear of the water wall tube in the corner area of ​​the furnace is also quite serious, especially due to installation reasons, the sealing fins overlap up and down, uneven, and not only wear the fins but also wash the tubes during operation. wall. An effective measure to prevent wear here is to weld the fins at the corners with pins and pour refractory and wear-resistant materials. The operation shows that the effect is better and it has been widely used.
3. Anti-wear countermeasures for pipe walls in irregular areas The wear and bursting of irregular water-cooled wall pipes are second only to the wear and bursting of wall pipes in the transition area between the lower part of the furnace and the water-cooled wall pipes. Due to the irregularity of the water wall pipes at the pressure measuring holes and manholes, the gas-solid two-phase flow can easily cause eddy current erosion and wear here. If no measures are taken, generally after 3000h of operation, serious wear and pipe burst will occur. For this purpose, the method of spraying cemented carbide or pouring wear-resistant refractory castables is used to achieve the purpose of anti-wear. The operation shows that the use of wear-resistant refractory castables can play a good anti-wear effect on irregular water-cooled wall pipes. In addition, due to the installation reasons, the installation welds, especially the upper and lower overlapping of the sealing fins, and the unevenness of the unevenness cause the wall surface to be uneven. The effective way to prevent wear is to smooth the raised welds, the concave welds to be straightened, and the iron pieces left over from the installation process or the pins without castables must be cleaned and ground smoothly.
4. Anti-wear countermeasures for general water-cooled wall tubes At present, no serious wear of the straight tubes of the furnace water-cooled wall tubes has been found. Generally, only the water-cooled wall tubes are found to be polished. The anti-wear of the water-cooled wall pipes in this area should be adjusted from the aspect of operation. On the premise of ensuring the amount of fluidizing air and oxygen, the amount of fluidizing air should be reduced as much as possible, and the negative pressure at the furnace outlet should not be too large; To ensure the coal particle size requirements of the circulating fluidized bed boiler, after the particle size is reduced, it can not only reduce electricity consumption, reduce boiler wear, but also increase the bed temperature and reduce ash combustibles.