Circulating fluidized bed boiler anti-erossion cause analysis

      Circulating fluidized bed boiler heating surface wear is a great threat to the normal operation of circulating fluidized bed boiler, the following content for circulating fluidized bed boiler common wear and tear analysis and corrective measures. 

　　Circulating fluidized bed boiler is a kind of high efficiency and low pollution, coal adaptability, strong load regulation ability, relatively cheap, relatively easy to grasp the technology of the boiler, domestic and foreign application practice shows that, compared with conventional pulverized coal boilers, the use of circulating fluidized bed boiler technology can make coal-fired power plant boiler exhaust in SO2 and NOx and other harmful gas content reduced by about 80%-90%, can effectively reduce the pollution of coal-fired power generation for the atmosphere, so in recent years circulating fluidized bed boiler in China has been widely promoted and used, now circulating fluidized bed boiler in China's power industry and industrial production has formed a very large scale. 

　　Although fluidized bed boilers have various advantages, but there is a problem has been plagued by circulating fluidized bed boiler operation and maintenance personnel, that is, serious wear of equipment, anti-wear measures are not effective, wear is coal or ash particles to a certain angle hit the surface of the heating surface tube, causing erosion wear, resulting in the loss of metal on the surface of the tube. The erosion wear is mainly the effect of impact and cutting, and cutting is the most important factor. Solid particles act as tiny cutting tools sliding on the relatively soft metal surface cutting grooves marks. Wear is a very complex failure process, which is not only influenced by force causes, but also closely related to a variety of factors such as material, environment, and medium, etc. CFB heated surface tube wear is influenced by coal particle and ash particle concentrations, particle characteristics, and fluid geometry. In the area of high solid particle concentration, the wear mainly depends on the relative motion of solid particles and flue gas flow with the heating surface. Wear is closely related to the flue gas flow rate, and the velocity of the solid particles is the main factor affecting wear. Therefore, the severe wear area usually occurs in the area of sudden change of flow rate, and the wear of the heating surface of CFB mainly occurs in the lower part of the combustion chamber, around the upper exit of the furnace chamber and the lower part of the screen type heating surface arranged in the combustion chamber. The serious wear of circulating fluidized bed boiler limits the boiler operation cycle, causing the unplanned stoppage rate to increase and the maintenance workload to increase. 

　　After years of experience accumulated in the operation and maintenance of various plants to see the main wear and tear of boilers include. 

　　1. Water-cooled wall tube wear in the furnace chamber 

　　1.1 wear analysis: a large number of flue gas and solid particles in the process of rising on the water-cooled wall tube scouring wear; on the other hand, a large number of solid particles along the four walls of the chamber back down, the water-cooled wall tube scouring wear. Especially in the water-cooled wall tube and the refractory layer transition area of the projection parts. Along the water-cooled wall tube down the formation of solid particles vortex, the local water-cooled tube wall plays a kind of planing role. 

　　1.2 Water-cooled wall wear analysis 

　　Water-cooled wall tube wear is mainly concentrated in three areas: the lower part of the furnace casting material and water-cooled wall tube transition area wall wear; furnace around the corner area wall wear; irregular area wall wear. The lower part of the furnace chamber and the water-cooled wall tube transition area wall wear: one is along the wall of the furnace downstream solid materials in the junction area to produce flow direction change, and thus the water-cooled wall tube scouring, the water-cooled wall tube wear; another reason is that in the transition area due to downstream solid materials along the wall and the furnace upward movement of solid materials in the opposite direction, in the local production of vortex flow, on the Water-cooled wall tube wear. The wear and tear of the tube wall in the corner area around the furnace is due to the high density of solid materials flowing downward from the wall in the corner area, while the flow state is also damaged. The wear of the wall in the irregular area is mainly due to the large disturbance of the local flow characteristics caused by the irregular wall. 

After years of technical research and development, our company officially launched the grille anti-friction technology to the market in 2014, and registered the national trademark "Jinliang" brand for this purpose. Around Jinliang grille anti-friction technology, 10 national patents have been applied so far.

　　Thermally conductive grille anti-friction technology.

　　Thermally conductive grating anti-wear technology is an active anti-wear technology that is installed with alloy grating plates along the horizontal and vertical directions on the surface of the water-cooled wall to form a mesh grating, blocking the formation of high-speed wall flow, optimizing the flow field on the surface of the water-cooled wall, eliminating local eddy currents, reducing the velocity of gas-solid two-phase flow against the wall, reducing the cutting force of material particles on the water-cooled wall, and thus effectively controlling the wear problem of the water-cooled wall.